MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Chemphyschem' source. Mon, 06 Feb 2012 12:54:58 +0100 http://www.medworm.com/index.php?rid=5621190&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22262316%26dopt%3DAbstract Authors: Biteen JS, Goley ED, Shapiro L, Moerner WE Abstract Single-molecule super-resolution imaging provides a non-invasive method for nanometer-scale imaging and is ideally suited to investigations of quasi-static structures within live cells. Here, we extend the ability to image subcellular features within bacteria cells to three dimensions based on the introduction of a cylindrical lens in the imaging pathway. We investigate the midplane protein FtsZ in Caulobacter crescentus with super-resolution imaging based on fluorescent-protein photoswitching and the natural polymerization/depolymerization dynamics of FtsZ associated with the Z-ring. We quantify these dynamics and determine the FtsZ depolymerization time to be <100 ms. We image the Z-ring in live and fixed C. cresce... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5621190 Fri, 20 Jan 2012 05:00:00 +0100 5621190 http://www.medworm.com/index.php?rid=5621189&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22262374%26dopt%3DAbstract Authors: Abraham SA, Jose D, Datta A Abstract The more the better: Calculations and crystal-structure analyses show that a single electron-rich aromatic ring can simultaneously bind to two cations on its top and bottom π surfaces. PMID: 22262374 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5621189 Fri, 20 Jan 2012 05:00:00 +0100 5621189 http://www.medworm.com/index.php?rid=5621198&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22250006%26dopt%3DAbstract Authors: Guilbaud P, Zemb T Abstract Reverse micelles? The transition from weak aggregation to water-poor reverse micelles triggered by the presence of extracted ion pairs is modeled using molecular dynamics simulations. The presence of the ion induces a polar/apolar segregation and the formation of a curved film microstructure consistent with the classical inverse micelle. PMID: 22250006 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5621198 Tue, 17 Jan 2012 05:00:00 +0100 5621198 http://www.medworm.com/index.php?rid=5621197&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22253133%26dopt%3DAbstract We present an overview of the application of dual-focus fluorescence correlation spectroscopy (2f-FCS) for the measurement of diffusion coefficients within free-standing lipid membranes. The first part gives a detailed theoretical analysis of the expected performance of 2f-FCS, in particular about the sensitivity of the method with regard to precise focus position and to aberrations caused by refractive index mismatch or cover slide thickness deviation. After describing the experimental details of the 2f-FCS setup and the preparation of free-standing black lipid membranes (BLMs), we apply the method to study the diffusion of lipids within BLMs as a function of lipid composition and of ion valency and ionic strength of the surrounding buffer. PMID: 22253133 [PubMed - as supplied by publ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5621197 Tue, 17 Jan 2012 05:00:00 +0100 5621197 http://www.medworm.com/index.php?rid=5621196&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22253145%26dopt%3DAbstract Authors: Shirota H Abstract In this minireview, the features of low-frequency spectra within the frequency range 0-200 cm(-1) for aromatic and nonaromatic cation based ionic liquids obtained by femtosecond Raman-induced Kerr effect spectroscopy are reviewed. For aromatic cation based ionic liquids, the aromatic group of the cations is largely responsible for the spectral line shape due to their larger polarizability anisotropy volume and more polarizable nature than nonaromatic cations. The low-frequency Kerr spectra are also compared with the bulk properties of the ionic liquids. The differences in the relationship of the first moment of the low-frequency spectrum band and the bulk properties between the aromatic and nonaromatic cation based ionic liquids with respect to the nat... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5621196 Tue, 17 Jan 2012 05:00:00 +0100 5621196 http://www.medworm.com/index.php?rid=5621195&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22253201%26dopt%3DAbstract Authors: Fückel B, Hinze G, Wu J, Müllen K, Basché T Abstract We measured electronic transitions of the 2D graphene-type molecule hexa-peri-hexabenzocoronene (HBC) at the single-molecule level. The large intersystem crossing rate and long triplet state lifetime in the range of seconds are prohibitive for direct single-molecule observation. By covalently coupling fluorescent acceptor molecules (perylenecarboximide, PMI) to HBC, efficient singlet energy transfer gives rise to strong PMI fluorescence. Confocal single-molecule fluorescence microscopy with two excitation colours matching the HBC and PMI transition frequencies, respectively, was conducted. Single HBC-6PMI molecules were readily observed via the PMI emission. It was found that after selective excitation of the HBC the ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5621195 Tue, 17 Jan 2012 05:00:00 +0100 5621195 http://www.medworm.com/index.php?rid=5621194&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22253208%26dopt%3DAbstract Authors: Sánchez-Sanz G, Trujillo C, Alkorta I, Elguero J Abstract A theoretical study of the HTeXH (X=O, S, Se and Te) monomers and homodimers was carried out by means of second-order Møller-Plesset perturbation theory (MP2) computational methods. In the case of monomers, the isomerization energy from HTeXH to H(2) Te=X and H(2) X=Te (X=O, S, Se, and Te) and the rotational transition-state barriers were obtained. Due to the chiral nature of these compounds, homo and heterochiral dimers were found. The electron density of the complexes was characterized with the atoms-in-molecules (AIM) methodology, finding a large variety of interactions. The charge transfer within the dimers was analyzed by means of natural bond orbitals (NBO). The density functional theory-symmetry adapted per... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5621194 Tue, 17 Jan 2012 05:00:00 +0100 5621194 http://www.medworm.com/index.php?rid=5621193&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22253215%26dopt%3DAbstract Authors: Malvankar NS, Mester T, Tuominen MT, Lovley DR Abstract Supercapacitors have attracted interest in energy storage because they have the potential to complement or replace batteries. Here, we report that c-type cytochromes, naturally immersed in a living, electrically conductive microbial biofilm, greatly enhance the device capacitance by over two orders of magnitude. We employ genetic engineering, protein unfolding and Nernstian modeling for in vivo demonstration of charge storage capacity of c-type cytochromes and perform electrochemical impedance spectroscopy, cyclic voltammetry and charge-discharge cycling to confirm the pseudocapacitive, redox nature of biofilm capacitance. The biofilms also show low self-discharge and good charge/discharge reversibility. The superio... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5621193 Tue, 17 Jan 2012 05:00:00 +0100 5621193 http://www.medworm.com/index.php?rid=5621192&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22253223%26dopt%3DAbstract Authors: Cao Z, Li S, Yan T Abstract A cation-π stacking structure consisting of a free-base porphyrin (FBP) and 1-butyl-3-methylimidazolium (BMIM(+) ) cation is demonstrated by both ab initio theory and polarizable force field. The isolated FBP-BMIM(+) complex forms a face-to-face alignment, and the polarizable force-field-optimized complex reproduces that by ab initio theory reasonably well. Molecular dynamics simulation finds that the stacking structure is slightly altered for the FBP dissolved in the bulk ionic liquid (IL) due to the complexity of the solution structure. In the bulk IL, the FBP is sandwiched between two BMIM(+) cations stacking on both sides of the FBP ring plane with a slipped-parallel alignment. Furthermore, the FBP-BMIM(+) stacking structure is found to be ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5621192 Tue, 17 Jan 2012 05:00:00 +0100 5621192 http://www.medworm.com/index.php?rid=5621191&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22253251%26dopt%3DAbstract Authors: Meuwly M Abstract Playing by the rules: A combined experimental/atomistic simulation approach is a powerful means to better understand chemical reactivity and to best take advantage of mode-specific processes, highlighted herein. PMID: 22253251 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5621191 Tue, 17 Jan 2012 05:00:00 +0100 5621191 http://www.medworm.com/index.php?rid=5578087&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223632%26dopt%3DAbstract Authors: Vallés-Pardo JL, Guijt MC, Iannuzzi M, Joya KS, de Groot HJ, Buda F Abstract Ab initio molecular dynamics simulations with an adaptive biasing potential are carried out to study the reaction path in mononuclear Ru catalysts for water oxidation of the type [(Ar)Ru(X)(bpy)](+) with different aromatic ligands (Ar). The critical step of the OO bond formation in the catalytic cycle starting from the [(Ar)Ru(O)(bpy)](2+) intermediate is analyzed in detail. It is shown that an explicit inclusion of the solvent environment is essential for a realistic description of the reaction path. Clear evidence is presented for a concerted reaction in which the OO bond formation is quickly followed by a proton transfer leading to a RuOOH intermediate and a hydronium ion. An alternat... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5578087 Wed, 11 Jan 2012 05:31:23 +0100 5578087 http://www.medworm.com/index.php?rid=5578085&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22228645%26dopt%3DAbstract Authors: Heydenryck G, Welter K, Flückinger M PMID: 22228645 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5578085 Wed, 11 Jan 2012 05:31:02 +0100 5578085 http://www.medworm.com/index.php?rid=5578084&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22228646%26dopt%3DAbstract Authors: PMID: 22228646 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5578084 Wed, 11 Jan 2012 05:30:51 +0100 5578084 http://www.medworm.com/index.php?rid=5578083&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22228647%26dopt%3DAbstract Authors: Maihom T, Choomwattana S, Khongpracha P, Probst M, Limtrakul J Abstract The stability of monomeric formaldehyde encapsulated in the lithium-decorated metal-organic framework Li-MOF-5 was investigated by means of density functional calculations with the M06-L functional and the 6-31G(d,p) basis set. To assess the efficiency of Li-MOF-5 for formaldehyde preservation, we consider the reaction kinetics and the thermodynamic equilibrium between formaldehyde and its trimerized product, 1,3,5-trioxane. We propose that trimerization of encapsulated formaldehyde takes place in a single reaction step with an activation energy of 34.5 kcal mol(-1) . This is 17.2 kcal mol(-1) higher than the corresponding activation energy in the bare system. In addition, the reaction energy of th... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5578083 Wed, 11 Jan 2012 05:30:41 +0100 5578083 http://www.medworm.com/index.php?rid=5578082&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22228648%26dopt%3DAbstract Authors: Hardzei M, Artemyev M, Molinari M, Troyon M, Sukhanova A, Nabiev I Abstract Fluorescence resonance energy transfer (FRET) in conjugates of CdSe-ZnS semiconductor nanocrystals of different shapes (FRET donors) and an Alexa Fluor organic dye (FRET acceptors) is examined. The dye molecules are chemically conjugated with quantum dots (QDs) or nanorods (NRs) in dimethyl sulfoxide colloidal solutions, and FRET efficiency in the purified conjugates is measured. The FRET from NR to a single dye molecule is less efficient than that of the QD-dye conjugates and this effect is explained in terms of distance-limited energy-transfer rate in the case of a point-like acceptor and extended donor dipoles. However, the larger surface area of NRs allows for many more dye acceptors to be boun... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5578082 Wed, 11 Jan 2012 05:30:30 +0100 5578082 http://www.medworm.com/index.php?rid=5578081&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22228649%26dopt%3DAbstract Authors: PMID: 22228649 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5578081 Wed, 11 Jan 2012 05:30:20 +0100 5578081 http://www.medworm.com/index.php?rid=5578086&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223217%26dopt%3DAbstract Authors: Mandal AK, Sen Mojumdar S, Das AK, Bhattacharyya K Abstract The effect of two room-temperature ionic liquids (RTILs) on the diffusion of three fluorescent dyes in the gel phase of a triblock copolymer, (PEO)(20) -(PPO)(70) -(PEO)(20) [Pluronic P123; poly ethylene oxide (PEO), poly propylene oxide (PPO)], was studied by using fluorescence correlation spectroscopy (FCS). We used three dyes, 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), coumarin 480 (C480), and coumarin 343 (C343). By field-emission scanning electron microscopy (FESEM), it was observed that the macroscopic structure of the P123 gel remained unaffected upon addition of RTIL. In the absence of RTIL, the diffusion coefficient (D(t) ) of the hydrophobic dye DCM (1 μm(2)  s(-1) at th... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5578086 Thu, 05 Jan 2012 05:00:00 +0100 5578086 http://www.medworm.com/index.php?rid=5559980&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213224%26dopt%3DAbstract Authors: Weijs JH, Seddon JR, Lohse D Abstract Using molecular dynamics, we study the nucleation and stability of bulk nanobubble clusters. We study the formation, growth, and final size of bulk nanobubbles. We find that, as long as the bubble-bubble interspacing is small enough, bulk nanobubbles are stable against dissolution. Simple diffusion calculations provide an excellent match with the simulation results, giving insight into the reason for the stability: nanobubbles in a cluster of bulk nanobubbles protect each other from diffusion by a shielding effect. PMID: 22213224 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559980 Mon, 02 Jan 2012 05:00:00 +0100 5559980 http://www.medworm.com/index.php?rid=5559979&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213246%26dopt%3DAbstract Authors: Borisenko N, Zein El Abedin S, Endres F Abstract Herein the structure of the interfacial layer between the air- and water-stable ionic liquid 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([EMIM]FAP) and Au(111) is investigated using in situ scanning tunneling microscopy (STM), distance tunneling spectroscopy (DTS) and cyclic voltammetry (CV) measurements. The in situ STM measurements reveal that structured interfacial layers can be probed in both cathodic and anodic regimes at the IL/Au(111) interface. The structure of these layers is dependent on the applied electrode potential, the number of subsequent STM scans and the scan rate. Furthermore, first DTS results show that the tunneling barrier during the 1st STM scan does not seem to change sig... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559979 Fri, 30 Dec 2011 05:00:00 +0100 5559979 http://www.medworm.com/index.php?rid=5559973&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213625%26dopt%3DAbstract Authors: Gole JL, Goude EC, Laminack W Abstract A concept describing the nanostructure-directed dynamics of acid/base interaction and the balance between physisorption and chemisorption on an extrinsic semiconductor interface is evaluated and compared for n- and p-type semiconductors. The inverse hard/soft acid/base (IHSAB) concept, as it complements the HSAB concept, defines the nature of a dominant physisorption behavior and enables the creation of a matrix of controllable interactions. The technology results in the coupling of Lewis acid/base chemistry with the extrinsic semiconductor majority carriers. Nanoporous silicon layers facilitate the application of nanostructured metal/metal oxides, which provide sensitivity and selectivity for the modified interface. Applied fractiona... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559973 Fri, 30 Dec 2011 05:00:00 +0100 5559973 http://www.medworm.com/index.php?rid=5559972&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213636%26dopt%3DAbstract Authors: Holmes-Smith AS, McDowell GR, Toury M, McLoskey D, Hungerford G Abstract The efficiency of Förster resonance energy transfer (FRET) can be enhanced in the presence of a metal. Herein, we demonstrate the increased efficiency for a novel model sensor system where FRET is shown to occur between Rhodamine 6G in the bulk sol-gel matrix and Texas Red, which is held a fixed distance away by covalent attachment onto a silane spacer. Silver colloids are formed using light to initiate the reduction of a silver salt, which can be achieved at controlled locations within the film. Both the fluorescence intensity and lifetime maps and analysis indicate that an enhanced FRET efficiency has been achieved in the presence of silver nanoparticles. An increase in efficiency of 1.2-1.5 ti... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559972 Fri, 30 Dec 2011 05:00:00 +0100 5559972 http://www.medworm.com/index.php?rid=5559970&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213654%26dopt%3DAbstract Authors: Baaske M, Vollmer F Abstract Optical resonator biosensors are emerging as one of the most sensitive microsystem biodetection technology that does not require amplification or labeling of the analyte. This minireview provides a scholarly introduction to this research area and reviews current advances in molecular diagnostics and nanoparticle detection. PMID: 22213654 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559970 Fri, 30 Dec 2011 05:00:00 +0100 5559970 http://www.medworm.com/index.php?rid=5559984&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213137%26dopt%3DAbstract Authors: Yang T, Zhao X, Li LS, Zheng JJ, Gao WY Abstract Endohedral metallofullerenes: Density functional theory studies reveal that the smallest gadolinium nitride cluster fullerene, Gd(3) N@C(2) (22010)C(78) , not only possesses a high kinetic stability but also a high thermodynamic stability. Further investigations on the electronic structure, properties and IR vibrational frequencies expose the important covalent interaction between the metal cluster and the carbon cage. PMID: 22213137 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559984 Fri, 23 Dec 2011 05:00:00 +0100 5559984 http://www.medworm.com/index.php?rid=5559983&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213160%26dopt%3DAbstract Authors: Nakata S, Matsuda Y, Ikura YS, Takeda A, Izumi S Abstract The self-motion of a benzoquinone (BQ) disk on NADPH was investigated as the coupling of an autonomous motor and an enzyme reaction. In the absence of the enzyme reaction, features of motion changed depending on the concentration of NADPH, that is, continuous motion→ intermittent oscillatory motion→ no motion. When the reverse reaction from NADP(+) to NADPH was introduced into the system with the addition of an enzyme reaction, continuous motion changed to intermittent oscillatory motion with small amplitude. The mechanism of this mode change is discussed in relation to the surface tension as a driving force and the time course of UV spectra as a window to the progress of the reaction. Characteristic features of... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559983 Fri, 23 Dec 2011 05:00:00 +0100 5559983 http://www.medworm.com/index.php?rid=5559982&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213185%26dopt%3DAbstract Authors: Carré S, Luchez F, Moissette A, Poizat O, Batonneau-Gener I Abstract The mere mixing of N-alkylphenothiazines with three channel-type acid zeolites with various structures (ferrierite, H-MFI, and mordenite) induces the spontaneous ionization of the heterocyclic molecule in high yield upon adsorption. The diffuse reflectance UV-visible absorption and Raman scattering spectra show that the accessibility of the highly polarizing acid sites is not indispensable to induce the spontaneous ionization process. Due to their particularly low ionization potential values (6.7 eV), the adsorption of the molecules on the external surface or in the inner volume is the key parameter to generate the radical cation. However, the ionization yield and charge stabilization are intimately co... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559982 Fri, 23 Dec 2011 05:00:00 +0100 5559982 http://www.medworm.com/index.php?rid=5559981&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213203%26dopt%3DAbstract We report a facile hydrothermal synthetic route to prepare a class of monodispersed lanthanide-based compound submicrospheres with controllable size, which employs raw lanthanide oxides as starting material, urea as precipitator and poly(N-vinyl-2-pyrrolidone) (PVP) as surfactant. Dependent on the intrinsic properties of respective lanthanide, the resulting products could be in the form of oxide, hydroxide or basic carbonate. These lanthanide hydroxides or basic carbonates can be easily transformed into their corresponding oxides by calcination, retaining the same morphology and size dispersion. The formation mechanism of these lanthanide-based compound submicrospheres is investigated and PVP plays a critical role in forming uniform and well-dispersed products. Furthermore, this method cou... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559981 Fri, 23 Dec 2011 05:00:00 +0100 5559981 http://www.medworm.com/index.php?rid=5559978&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213457%26dopt%3DAbstract Authors: Carleschi E, Magnano E, Melli M, Lazzarino M Abstract Where you want it, when you want it: When cleaved in vacuum, a semiconductor exposes a highly reactive surface that can be exploited to obtain well controlled chemical bonds. Now, using sacrificial microstructures and a 2+2 cycloaddition process, organic molecules are covalently bound to a silicon pre-patterned surface in liquid environment with accurate spatial control. PMID: 22213457 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559978 Fri, 23 Dec 2011 05:00:00 +0100 5559978 http://www.medworm.com/index.php?rid=5559977&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213520%26dopt%3DAbstract Authors: Giner-Casares JJ, Keller J, Rotger C, Costa A, Brezesinski G Abstract New moiety for drug design: The chemical group squaramide shows promising results in medicinal chemistry. The mechanism of action of cyclic oligosquaramides at biological membranes is revealed by a monolayer study. The biological activity is related to the hydrophobicity of the new squaramide-derivative drugs. PMID: 22213520 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559977 Fri, 23 Dec 2011 05:00:00 +0100 5559977 http://www.medworm.com/index.php?rid=5559976&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213552%26dopt%3DAbstract We report on a minimal system to mimic intracellular transport of membrane-bounded, vesicular cargo. In a cell-free assay, purified kinesin-1 motor proteins were directly anchored to the membrane of giant unilamellar vesicles, and their movement studied along two-dimensional microtubule networks. Motion-tracking of vesicles with diameters of 1-3 μm revealed traveling distances up to the millimeter range. The transport velocities were identical to velocities of cargo-free motors. Using total internal reflection fluorescence (TIRF) microscopy, we were able to estimate the number of GFP-labeled motors involved in the transport of a single vesicle. We found that the vesicles were transported by the cooperative activity of typically 5-10 motor molecules. The presented assay is expected to op... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559976 Fri, 23 Dec 2011 05:00:00 +0100 5559976 http://www.medworm.com/index.php?rid=5559975&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213579%26dopt%3DAbstract Authors: Jacobsen H, Cavallo L Abstract The performance of a series of density functionals when tested on the prediction of the phosphane substitution energy of transition metal complexes is evaluated. The complexes FeBDA and RuCOD (BDA=benzylideneacetone, COD=cyclooctadiene) serve as reference systems, and calculated values are compared with the experimental values in THF as obtained from calorimetry. Results clearly indicate that functionals specifically developed to include dispersion interactions usually outperform other functionals when BDA or COD substitution is considered. However, when phosphanes of different sizes are compared, functionals including dispersion interactions, at odd with experimental evidence, predict that larger phosphanes bind more strongly than smal... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559975 Fri, 23 Dec 2011 05:00:00 +0100 5559975 http://www.medworm.com/index.php?rid=5559974&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213596%26dopt%3DAbstract Authors: Blaudeck T, Zenkevich EI, Abdel-Mottaleb M, Szwaykowska K, Kowerko D, Cichos F, von Borczyskowski C Abstract Functional dye molecules, such as porphyrins, attached to CdSe quantum dots (QDs) through anchoring meso-pyridyl substituents, form quasi-stable nanoassemblies. This fact results in photoluminescence (PL) quenching of the QDs both due to Förster resonance energy transfer (FRET) and the formation of non-radiative surface states under conditions of quantum confinement (non-FRET). The formation process is in competition with the ligand dynamics. At least two timescales are found for the formation of the assemblies: 1) one faster than 60 s attributed to saturation of empty attachment sites and 2) one slower than 600 s, which is attributed to a reorganisation of... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559974 Fri, 23 Dec 2011 05:00:00 +0100 5559974 http://www.medworm.com/index.php?rid=5559971&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213647%26dopt%3DAbstract Authors: Bates M, Dempsey GT, Chen KH, Zhuang X Abstract Understanding the complexity of the cellular environment will benefit from the ability to unambiguously resolve multiple cellular components, simultaneously and with nanometer-scale spatial resolution. Multicolor super-resolution fluorescence microscopy techniques have been developed to achieve this goal, yet challenges remain in terms of the number of targets that can be simultaneously imaged and the crosstalk between color channels. Herein, we demonstrate multicolor stochastic optical reconstruction microscopy (STORM) based on a multi-parameter detection strategy, which uses both the fluorescence activation wavelength and the emission color to discriminate between photo-activatable fluorescent probes. First, we obtained two... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5559971 Fri, 23 Dec 2011 05:00:00 +0100 5559971 http://www.medworm.com/index.php?rid=5549720&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22180329%26dopt%3DAbstract Authors: PMID: 22180329 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549720 Fri, 23 Dec 2011 05:00:00 +0100 5549720 http://www.medworm.com/index.php?rid=5549719&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22180330%26dopt%3DAbstract Authors: PMID: 22180330 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549719 Fri, 23 Dec 2011 05:00:00 +0100 5549719 http://www.medworm.com/index.php?rid=5549713&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22190476%26dopt%3DAbstract Authors: Liu L, Li T, Lee M Abstract Chiral films are obtained from achiral rigid-flexible molecules. Due to hydrogen bonding and steric constraints, these molecules can self-assemble into chiral assemblies at the air/water interface upon compression. When the molecules are spread on a subphase containing AgNO(3) , they form a stable monolayer through coordination with Ag(I) ions, as confirmed by surface pressure-area isotherms, UV/Vis and FTIR spectroscopy, and AFM. More interestingly, macroscopic chirality was detected in the Ag(I) -coordinated films by circular dichroism measurements. The formation mechanisms of the two kinds of chiral films are briefly discussed. PMID: 22190476 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549713 Wed, 21 Dec 2011 05:00:00 +0100 5549713 http://www.medworm.com/index.php?rid=5549712&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22190482%26dopt%3DAbstract Authors: Karki K, Helms G, Namboodiri M, Wagner V, Fritz J, Materny A Abstract Elementary processes like energy transfer, charge transport, and exciton diffusion in thin films occur on time scales of femtoseconds. Time-resolved photo-electron spectroscopy,([1, 2]) a technique limited to ultra-high vacuum environment and the proper choice of a substrate, has been used to study ultrafast processes in sub-nanometer thin films so far. Herein we show that a transient (population) grating([3]) created by the interference of laser pulses can be used to study ultrafast processes in such films under ambient conditions. Our investigations of exciton dynamics in 1.4±0.2 nm and 0.4±0.2 nm thin films, formed by nanocrystals of 3,4,9,10-Perylenetetracarboxylic dianhydride (PTCDA) on glas... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549712 Tue, 20 Dec 2011 05:00:00 +0100 5549712 http://www.medworm.com/index.php?rid=5549718&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22183913%26dopt%3DAbstract Structures and Fragmentation of [Cu(Uracil-H)(Uracil)](+) in the Gas Phase. Chemphyschem. 2011 Dec 19; Authors: Ali OY, Fridgen TD Abstract Complexes of copper (II) ions and uracil were studied using tandem mass spectrometry (Fourier transform ion cyclotron resonance, FTICR, mass spectrometry) including extensive isotopic labeling as well as theoretical calculations. Positive ion electrospray mass spectra of aqueous solutions of CuCl(2) and uracil show that the [Cu(Ura-H)(Ura)](+) ion is the most abundant ion even at low concentrations of uracil. Sustained off-resonance irradiation collision-induced dissociation (SORI-CID) experiments show that the lowest energy decomposition pathway for [Cu(Ura-H)(Ura)](+) , surprisingly, is not the loss of uracil, but the loss of HNCO fol... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549718 Mon, 19 Dec 2011 05:00:00 +0100 5549718 http://www.medworm.com/index.php?rid=5549717&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22183928%26dopt%3DAbstract Authors: Lin H, Centeno SP, Su L, Kenens B, Rocha S, Sliwa M, Hofkens J, Uji-I H Abstract Photoactivation localization microscopy (PALM) was applied to study surface-enhanced fluorescence (SEF) on metal nanostructures (SEF-PALM). The detection of fluorescence from individual single molecules can be used to image the point-spread-function and spatial distribution of the fluorescence emitted in the vicinity of a metal surface. Due to the strong scattering effect, the angular distribution of the fluorescence is altered by metals, resulting in a spatial shift of fluorescence spots with respect to the metal nanostructures, and has to be taken into account in the analysis. SEF-PALM can be used to discriminate effects of labelling density when estimating the enhancement factor in SEF. Fur... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549717 Mon, 19 Dec 2011 05:00:00 +0100 5549717 http://www.medworm.com/index.php?rid=5549716&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22184012%26dopt%3DAbstract Authors: Strackharn M, Stahl SW, Severin PM, Nicolaus T, Gaub HE Abstract Molecule-by-molecule arrangement of proteins, for example, in enzymatic networks of predefined composition and proximity, is a major goal that may be accomplished by the single-molecule cut-and-paste technique (SMC&P). For this purpose, co-expressed anchors and handles as protein tags should be employed. As a first step in this direction, the authors develop an SMC&P design which exploits an antibody-peptide complex as a molecular handle. PMID: 22184012 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549716 Mon, 19 Dec 2011 05:00:00 +0100 5549716 http://www.medworm.com/index.php?rid=5549715&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22184036%26dopt%3DAbstract Authors: Wang Q, Cha CS, Lu J, Zhuang L Abstract It is commonly recognized that the ionic conductivity of pure water is very poor because of very low ionic concentrations. However, this work indicates that pure water in charged porous matrixes can be moderately conductive because of the ions in the electric double layer established at the solid/water interfaces. The ionic conductivity of pure water in a charged matrix changes with the electrode potential of the matrix and is influenced by the structural parameters. Both experimental measurements and theoretical calculations reveal that ionic conductivity may reach the order of 10(-3)  S cm(-1) in commonly accessible potential region in a porous matrix made of gold nanoparticles. These results would help to understand and optimi... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549715 Mon, 19 Dec 2011 05:00:00 +0100 5549715 http://www.medworm.com/index.php?rid=5549714&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22184072%26dopt%3DAbstract Authors: Gaiduk A, Yorulmaz M, Ishow E, Orrit M Abstract Organic nanoparticles made of a push-pull triarylamine dye with an average diameter of 60 nm, were prepared by reprecipitation. We study their photophysical properties by a combination of photothermal and fluorescence microscopy. Photothermal contrast provides a quantitative measure of the number of absorbers. The size of nanoparticles estimated from the absorption measurements was compared with sizes measured by AFM. Fluorescence and absorption microscopy provide quantum yield on the single-particle level as a function of excitation intensity. The quantum yield strongly decreases at high intensities because of singlet-singlet or singlet-triplet annihilation. We also report the formation of molecular thin layers and of laby... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549714 Mon, 19 Dec 2011 05:00:00 +0100 5549714 http://www.medworm.com/index.php?rid=5549721&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22174079%26dopt%3DAbstract Authors: Chrostowska A, Matrane A, Maki D, Khayar S, Ushiki H, Graciaa A, Belachemi L, Guillemin JC Abstract Simple unsaturated and cyclopropylic isocyanides are synthesized by an efficient and simple approach. These compounds with gradually increasing distance between the unsaturated moiety and the isonitrile group are studied by UV photoelectron spectroscopy and quantum chemical calculations, and also compared to the corresponding nitriles. The first photoelectron band of the unsaturated compounds is linked to removal of an electron from the HOMO, which corresponds to CC multiple-bond ionization in antibonding interaction with the π-isocyanide bond (in the same plane) for conjugated systems, or in antibonding interaction with the pseudo-π-CH(2) group for isolated systems. For t... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549721 Thu, 15 Dec 2011 05:00:00 +0100 5549721 http://www.medworm.com/index.php?rid=5549722&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170696%26dopt%3DAbstract Authors: Rubeš M, Grajciar L, Bludský O, Wiersum AD, Llewellyn PL, Nachtigall P Abstract The adsorption of CO in metal-organic framework CuBTC material is investigated by a combination of theoretical and experimental approaches. The adsorption enthalpy of CO on CuBTC determined experimentally to be -29 kJ mol(-1) at the zero-coverage limit is in very good agreement with the adsorption enthalpy calculated at the combined DFT-ab initio level with the periodic model. Calculations show that polycarbonyl complexes cannot be formed on regular coordinatively unsaturated sites in CuBTC. Experimental IR spectra of the CO probe molecule adsorbed in CuBTC are interpreted based on calculated CO stretching frequencies. Calculations show that long-range interactions are insignificant for t... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549722 Tue, 13 Dec 2011 05:00:00 +0100 5549722 http://www.medworm.com/index.php?rid=5549725&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22162355%26dopt%3DAbstract Authors: Hao Z, Wu X, Sun R, Ma C, Zhang X Abstract To investigate the effect of sulfur-sulfur and metal-ligand coordination on the molecular structure and morphology of self-assembled nanostructures, metal-free 2,3,9,10,16,17,23,24-octakis(isopropylthio)phthalocyanine H(2) Pc(β-SC(3) H(7) )(8) (1) and its copper and lead congeners CuPc(β-SC(3) H(7) )(8) (2) and PbPc(β-SC(3) H(7) )(8) (3) are synthesized and fabricated into organic nanostructures by a phase-transfer method. The self-assembly properties are investigated by electronic absorption and Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Experimental results reveal different mole... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549725 Mon, 12 Dec 2011 05:00:00 +0100 5549725 http://www.medworm.com/index.php?rid=5549724&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22162395%26dopt%3DAbstract Authors: Campo-Cacharrón A, Cabaleiro-Lago EM, Rodríguez-Otero J Abstract The characteristics of the interaction of anions with naphthalendiimides, the basic structural motif of a newly synthesized anion channel based on anion⋅⋅⋅π interactions, are studied by computational methods. Stable complexes are formed with bromide, chloride, fluoride or hydroxide anions, which exhibit strong anion⋅⋅⋅π interactions in the gas phase. Following the sequence of the polarizing power of the anions, hydroxide and fluoride complexes are the most strongly interacting. The presence of a small number of water molecules strongly affects the anion⋅⋅⋅π interactions, especially for hydroxide and fluoride complexes, so the differences in interaction strength among the anions drop sig... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549724 Mon, 12 Dec 2011 05:00:00 +0100 5549724 http://www.medworm.com/index.php?rid=5549723&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22162421%26dopt%3DAbstract Authors: Chen X, Dai H, Li J, Huang X, Wei Z Abstract Clarifying the contribution of tryptophan (Trp) to electron-transfer (ET) processes in different protein surroundings can help to understand the effective pathway of ET in proteins. Interactions between Trp residues and protein microsurroundings involve intermolecular H-bonds, cation and π-electron clouds of aromatic rings, the secondary structure and π orbital of aromatic rings, and so on. Detailed analyses reveal that the microsurroundings play an important role in modulating the electron-relay function of Trp in proteins. Generally, microsurroundings with strong Lewis acidity inhibit electron hole transport through Trp residues. Systems with weak Lewis acidity finely tune the electron-relay ability of Trp in proteins, while... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5549723 Mon, 12 Dec 2011 05:00:00 +0100 5549723 http://www.medworm.com/index.php?rid=5493176&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22113927%26dopt%3DAbstract Computation of Hyperfine Tensors for Dinuclear Mn(III) Mn(IV) Complexes by Broken-Symmetry Approaches: Anisotropy Transfer Induced by Local Zero-Field Splitting. Chemphyschem. 2011 Dec 9;12(17):3170-9 Authors: Schraut J, Arbuznikov AV, Schinzel S, Kaupp M Abstract Based on broken-symmetry density functional calculations, the (55) Mn hyperfine tensors of a series of exchange-coupled, mixed-valence, dinuclear Mn(III) Mn(IV) complexes have been computed. We go beyond previous quantum chemical work by fully including the effects of local zero-field splitting (ZFS) interactions in the spin projection, following the first-order perturbation formalism of Sage et al. [J. Am. Chem. Soc. 1989, 111, 7239]. This allows the ZFS-induced transfer of hyperfine anisotropy from the Mn(III) s... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493176 Fri, 09 Dec 2011 05:00:00 +0100 5493176 http://www.medworm.com/index.php?rid=5493174&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22113958%26dopt%3DAbstract Authors: Goerigk L, Kruse H, Grimme S Abstract Dispersion-corrected density functional theory is assessed on the new S66 and S66x8 benchmark sets for non-covalent interactions. In total, 17 different density functionals are evaluated. Two flavors of our latest additive London-dispersion correction DFT-D3 and DFT-D3(BJ), which differ in their short-range damping functions, are tested. In general, dispersion corrections are again shown to be crucial to obtain reliable non-covalent interaction energies and equilibrium distances. The corrections strongly diminish the performance differences between the functionals, and in summary most dispersion-corrected methods can be recommended. DFT-D3 and DFT-D3(BJ) also yield similar results but for most functionals and intermolecular distances, ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493174 Fri, 09 Dec 2011 05:00:00 +0100 5493174 http://www.medworm.com/index.php?rid=5493166&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22144371%26dopt%3DAbstract Authors: Batista VS, Grimme S, Reiher M PMID: 22144371 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493166 Fri, 09 Dec 2011 05:00:00 +0100 5493166 http://www.medworm.com/index.php?rid=5493165&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22144372%26dopt%3DAbstract Authors: PMID: 22144372 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493165 Fri, 09 Dec 2011 05:00:00 +0100 5493165 http://www.medworm.com/index.php?rid=5493164&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22144373%26dopt%3DAbstract Authors: Vogiatzis KD, Klopper W, Mavrandonakis A, Fink K Abstract Magnetic exchange-coupling constants of tri- and dinuclear transition-metal complexes (paddlewheels) have been computed using various ab initio methods. The di- and trinuclear complexes under study may serve as secondary building units in metal-organic frameworks (MOFs). Multi-reference methods such as the complete-active-space self-consistent-field method (CASSCF) as well as second-order perturbation theory (CASPT2) yield spin ladders from which the magnetic exchange-coupling constants are obtained. For the dicobalt paddlewheels, inclusion of spin-orbit coupling is crucial for obtaining a qualitatively correct description of the system. Density functional theory (DFT) was applied in the framework of the broken-symm... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493164 Fri, 09 Dec 2011 05:00:00 +0100 5493164 http://www.medworm.com/index.php?rid=5493163&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22144374%26dopt%3DAbstract Oxidative Addition of the C(α) C(β) Bond in β-O-4 Linkage of Lignin to Transition Metals Using a Relativistic Pseudopotential-Based ccCA-ONIOM Method. Chemphyschem. 2011 Dec 9;12(17):3320-30 Authors: Oyedepo GA, Wilson AK Abstract A multi-level multi-layer QM/QM method, the relativistic pseudopotential correlation-consistent composite approach within an ONIOM framework (rp-ccCA-ONIOM), was applied to study the oxidative addition of the C(α) C(β) bond in an archetypal arylglycerol β-aryl ether (β-O-4 linkage) substructure of lignin to Ni, Cu, Pd and Pt transition metal atoms. The chemically active high-level layer is treated using the relativistic pseudopotential correlation-consistent composite approach (rp-ccCA), an efficient methodology designed to reproduce ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493163 Fri, 09 Dec 2011 05:00:00 +0100 5493163 http://www.medworm.com/index.php?rid=5493162&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22144375%26dopt%3DAbstract Authors: Ončák M, Berka K, Slavíček P Abstract We have investigated the sulfilimine covalent link between methionine (Met) and lysine (Lys), recently identified in collagen IV (R. Vanacore, A.-J. L. Ham, M. Voehler, C. R. Sanders, T. P. Conrads, T. D. Veenstra, K. B. Sharpless, P. E. Dawson, B. G. Hudson, Science 2009, 325, 1230), and have explored its stability with respect to both the redox processes and UV radiation by means of advanced computational methods. We have concluded that the bond should be present in a protonated state, (NH=S)(+) . The bond is characterized by a relatively high standard reduction potential, that is, the bond should not be stable in a typical cell environment; if the sulfilimine bond exists (as suggested by the experiment) then the bond has t... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493162 Fri, 09 Dec 2011 05:00:00 +0100 5493162 http://www.medworm.com/index.php?rid=5493161&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22144376%26dopt%3DAbstract Authors: PMID: 22144376 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493161 Fri, 09 Dec 2011 05:00:00 +0100 5493161 http://www.medworm.com/index.php?rid=5493160&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22147498%26dopt%3DAbstract Interplay between Defect Structure and Catalytic Activity in the Mo(10-x) V(x) O(y) Mixed-Oxide System. Chemphyschem. 2011 Dec 6; Authors: Jakes P, Blickhan N, Jekewitz T, Drochner A, Vogel H, Fuess H, Eichel RA Abstract The Mo(10-x) V(x) O(y) solid-solution systems (0≤x≤10) were studied by electron paramagnetic resonance spectroscopy. The results show the existence of paramagnetic vanadyl VO(2+) species, whose concentration becomes maximal for Mo(5) V(5) O(y) . A quantitative analysis of the [VO(2+) ] concentration as a function of the Mo/V ratio allows it to characterize the prevailing defect chemistry in the Mo(10-x) V(x) O(y) system. In this respect, the semi-conducting properties of Mo(10-x) V(x) O(y) are p-type in an interval of Mo(9) V(1) O(y) -Mo(5) V(5) O(y) an... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493160 Tue, 06 Dec 2011 05:00:00 +0100 5493160 http://www.medworm.com/index.php?rid=5493159&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22147515%26dopt%3DAbstract Free-Standing Arrays of Isolated TiO(2) Nanotubes through Supercritical Fluid Drying. Chemphyschem. 2011 Dec 6; Authors: Deneault JR, Xiao X, Kang TS, Wang JS, Wai CM, Brown GJ, Durstock MF Abstract A common complication in fabricating arrays of TiO(2) nanotubes is that they agglomerate into tightly packed bundles during the inevitable solvent evaporation step. This problem is particularly acute for template-fabricated TiO(2) nanotubes, as the geometric tunability of this technique enables relatively large inter-pore spacings or, from another perspective, more space for lateral displacement. Our work showed that agglomeration results from the surface tension forces that are present as the ambient solvent is evaporated from the nanotube film. Herein, we report a processing a... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493159 Tue, 06 Dec 2011 05:00:00 +0100 5493159 http://www.medworm.com/index.php?rid=5493158&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22147536%26dopt%3DAbstract Authors: Calvo F, Parneix P Abstract The influence of one or several infrared laser pulses on the stability of bare and argon-tagged sodium chloride clusters is investigated theoretically by a combination of computational methods involving explicit molecular dynamics and properly calibrated unimolecular rate theories. The fragmentation spectra obtained by varying the laser frequency in the far-IR range is compared to the linear absorption spectrum resulting from the dipole moment autocorrelation function. Under appropriate laser field parameters, the action spectra are found to resemble the absorption spectra quite accurately in terms of positions, line widths, and even relative intensities. However, the action spectra exhibit residual and systematic redshifts of a few percent, whi... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493158 Tue, 06 Dec 2011 05:00:00 +0100 5493158 http://www.medworm.com/index.php?rid=5493157&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22147552%26dopt%3DAbstract Authors: Li Y, Sanampudi A, Raji Reddy V, Biswas S, Nandakumar K, Yemane D, Goettert J, Kumar CS Abstract The size evolution of gold nanoparticles in a millifluidic reactor is investigated using spatially resolved transmission electron microscopy (TEM). The experimental data is supported by numerical simulations, carried out to study the residence-time distribution (RTD) of tracers that have the same properties as Au ions. Size and size distribution of the particles within the channels are influenced by the mixing zones as well as the RTD. However, the Au nanoparticles obtained show a broader size distribution even at the shortest investigated residence time of 3.53 s, indicating that in addition to surface growth reaction kinetics also plays an important role. The comparison of ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493157 Tue, 06 Dec 2011 05:00:00 +0100 5493157 http://www.medworm.com/index.php?rid=5493156&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22147562%26dopt%3DAbstract Authors: Elahifard MR, Jigato MP, Niemantsverdriet JW Abstract CO dissociation: Three most probable pathways to CO dissociation on the Fe (100) surface exist: a) direct, CO→C+O (-) and H-assisted b) H+CO↔HCO→CH + O (-) or c) CO+H↔COH→C+OH (-). Under high hydrogen pressure conditions and highly occupied surfaces the formation of HCO and subsequent dissociation to CH+O may at best compete with direct dissociation. PMID: 22147562 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493156 Tue, 06 Dec 2011 05:00:00 +0100 5493156 http://www.medworm.com/index.php?rid=5493169&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22135080%26dopt%3DAbstract Authors: Quintana SS, Falcone RD, Silber JJ, Correa NM Abstract The water/sodium bis(2-ethylhexyl) phosphate (NaDEHP) reverse micelle (RM) system is revisited by using, for the first time, molecular probes to investigate interface properties. The solvatochromic behavior of 1-methyl-8-oxyquinolinium betaine (QB) and 6-propionyl-2-(N,N-dimethyl)aminonaphthalene (PRODAN) in the water/NaDEHP/toluene system is studied, and the results are compared with those obtained in water/sodium 1,4-bis(2-ethylhexyl) sulfosuccinate (AOT)/toluene RM media. The results demonstrate that the micropolarity, microviscosity, interfacial water structure, molecular probe partition, and intramolecular electron-transfer processes are dramatically altered for NaDEHP RM interfaces in comparison to the AOT system... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493169 Thu, 01 Dec 2011 05:00:00 +0100 5493169 http://www.medworm.com/index.php?rid=5493168&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22135099%26dopt%3DAbstract Authors: Orth A, Johannes L, Römer W, Steinem C Abstract The architecture of the plasma membrane is not only determined by the lipid and protein composition, but is also influenced by its attachment to the underlying cytoskeleton. Herein, we show that microscopic phase separation of "raft-like" lipid mixtures in pore-spanning bilayers is strongly determined by the underlying highly ordered porous substrate. In detail, lipid membranes composed of DOPC/sphingomyelin/cholesterol/Gb(3) were prepared on ordered pore arrays in silicon with pore diameters of 0.8, 1.2 and 2 μm, respectively, by spreading and fusion of giant unilamellar vesicles. The upper part of the silicon substrate was first coated with gold and then functionalized with a thiol-bearing cholesterol derivative renderi... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493168 Thu, 01 Dec 2011 05:00:00 +0100 5493168 http://www.medworm.com/index.php?rid=5493167&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22135109%26dopt%3DAbstract Authors: Aragó J, Ponce Ortiz R, Nieto-Ortega B, Hernández V, Casado J, Facchetti A, Marks TJ, Viruela PM, Ortí E, López Navarrete JT Abstract This work investigates the evolution of the molecular, vibrational, and optical properties within a family of carbonyl-functionalized quaterthiophenes: 5,5'''-diheptanoyl-2,2':5',2'':5'',2'''-quaterthiophene (1), 5,5'''-diperfluorohexylcarbonyl-2,2':5',2'':5'',2'''-quaterthiophene (2), and 2,7-[bis(5-perfluorohexylcarbonylthien-2-yl)]-4H-cyclopenta[2,1-b:3,4-b']-dithiophene-4-one (3). The analysis is performed by Raman and UV/Vis absorption/excitation/fluorescence spectroscopy in combination with density functional calculations. Theoretical calculations show that substitution with carbonyl groups and perfluorohexyl chains induces progres... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493167 Thu, 01 Dec 2011 05:00:00 +0100 5493167 http://www.medworm.com/index.php?rid=5493171&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22128113%26dopt%3DAbstract This study helps to optimize the applications of ILs in related fields, as well as the recycling of ILs in the presence of water. PMID: 22128113 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493171 Wed, 30 Nov 2011 05:00:00 +0100 5493171 http://www.medworm.com/index.php?rid=5493170&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22131283%26dopt%3DAbstract Authors: Davami K, Ghassemi HM, Yassar RS, Lee JS, Meyyappan M Abstract As the applications for inorganic nanowires continuously grow, studies on the stability of these structures under high electrical/thermal stress conditions are needed. ZnTe nanowires are grown by the vapor-liquid-solid technique and their breakdown under Joule heating is studied through in situ monitoring in a transmission electron microscope (TEM). The experimental setup, consisting of a scanning tunneling microscope (STM) and a movable piezotube inside the TEM, allows the manipulation of a single nanowire. A voltage applied to the STM tip in contact with a ZnTe nanowire leads to the breakdown of the nanowire into Zn and Te particles or balls which is observed in real time. These balls grow by Ostwald ripeni... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493170 Wed, 30 Nov 2011 05:00:00 +0100 5493170 http://www.medworm.com/index.php?rid=5493173&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22120926%26dopt%3DAbstract Authors: Chen X, Rinkevicius Z, Luo Y, Agren H, Cao Z Abstract α-Santonin is the first organic compound observed to feature a photoinduced rearrangement and is now known to undergo a series of photochemical processes under UV irradiation. On the basis of the considerable interest of this system as a prototype, and of the yet limited insights reached for the basic photo mechanisms, we calculate the high-level electronic structures and explore the potential energy surfaces (PES) of α-santonin in the ground and lowest-lying excited states, their couplings, and the possible photoinduced isomerization pathways. The calculations identify the low-lying singlet excited state (1) (nπ*) accessible under light irradiation, which decays to the low-energy (3) (ππ*) state through an intersy... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493173 Fri, 25 Nov 2011 05:00:00 +0100 5493173 http://www.medworm.com/index.php?rid=5493172&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22120955%26dopt%3DAbstract We report on the electrochemical synthesis of free-standing aluminium nanowire architectures through a template-assisted electrodeposition technique. For this purpose, nuclear track-etched polycarbonate membranes were employed as templates. One side of the template was sputtered with a thin gold film to serve as a working electrode. Subsequently the nanowires were made in the ionic liquid 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl)/AlCl(3) (40/60 mol %) under potentiostatic conditions. Two different electrodeposition procedures were employed to fabricate strongly adherent Al nanowire structures on an electrodeposited Al layer. In the first procedure, electrodeposition simultaneously occurs along the pores of the template and on the Au-sputtered side of the template. In the second p... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493172 Fri, 25 Nov 2011 05:00:00 +0100 5493172 http://www.medworm.com/index.php?rid=5493175&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22113937%26dopt%3DAbstract Authors: Popeney CS, Setaro A, Mutihac RC, Bluemmel P, Trappmann B, Vonneman J, Reich S, Haag R Abstract A series of nonionic amphiphiles derived from polyglycerol dendrons were studied for their ability to solubilize and isolate single-walled carbon nanotubes. The amphiphiles possessed differently sized polar head groups, hydrophobic tail units, and various aromatic and non-aromatic groups between the head and tail groups. Absorbance analysis revealed that amphiphiles with anchor groups derived from pyrene were far inferior to those that possessed simple linear aliphatic tail groups. Absorbance and near-infrared fluorescence analyses revealed a weak dependence on the dendron size of the head group, but a strong positive trend in suspended nanotube density and fluorescence intensit... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5493175 Wed, 23 Nov 2011 05:00:00 +0100 5493175 http://www.medworm.com/index.php?rid=5439918&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22109993%26dopt%3DAbstract Authors: Gou Q, Feng G, Evangelisti L, Maris A, Marchini M, Velino B, Caminati W Abstract The rotational spectrum of the tetrahydrofuran-krypton van der Waals complex has been investigated by pulsed-jet Fourier transform microwave spectroscopy. The spectra of the (84) Kr and (86) Kr isotopologues have been assigned and the krypton atom is located nearly over the oxygen atom, almost perpendicular to the COC plane. Each rotational transition is split into two component lines due to, according to the observed Coriolis coupling term between the tunneling states, the residual pseudorotational effects of the ring in the complex. The splitting between the two vibrational sublevels is 87.462(2) and 87.062(2) MHz for the (84) Kr and (86) Kr isotopologues, respectively. These splittings ha... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5439918 Wed, 23 Nov 2011 05:00:00 +0100 5439918 http://www.medworm.com/index.php?rid=5439922&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22106031%26dopt%3DAbstract New Chemical Insights Using Weakly Supported Voltammetry: Ion Pairing in the EC(2) Reduction of 2,6-Diphenylpyrylium in Acetonitrile. Chemphyschem. 2011 Nov 22; Authors: Barnes EO, Wang Y, Belding SR, Compton RG Abstract Pairing effect: Varying the concentration of support electrolyte in the electrochemical EC(2) reduction of 2,6-diphenylpyrylium reveals the presence of ion pairing between the electroactive species and BF(4) (-) . Experiment and theory are shown to be in good agreement only if ion pairing is included in the simulations. This previously unanticipated effect is only observable if voltammetry is performed under conditions of weak support. PMID: 22106031 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5439922 Tue, 22 Nov 2011 05:00:00 +0100 5439922 http://www.medworm.com/index.php?rid=5439921&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22106039%26dopt%3DAbstract Authors: Fievez T, Geerlings P, Weckhuysen BM, Proft FD Abstract The oxidation of methanol on supported molybdenum oxides was studied using DFT. Starting from a cluster model for a mono-oxo and di-oxo molybdenum oxide on a SiO(2) support, the reaction energies and rates for the oxidation of methanol were computed and interpreted with chemical reaction indices. This pointed out that the apparent barrier was significantly lower on the mono-oxide model, favoring it over the di-oxo species. Accordingly, we assumed similar behavior on Al(2) O(3) , TiO(2) and ZrO(2) supports, so that we could compare characteristics over different supports. The obtained reaction energies and rates followed the experimental turn-over frequency (TOF) sequence. PMID: 22106039 [PubMed - as supplied by pu... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5439921 Tue, 22 Nov 2011 05:00:00 +0100 5439921 http://www.medworm.com/index.php?rid=5439919&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22106051%26dopt%3DAbstract Authors: Ninković DB, Janjić GV, Veljković DZ, Sredojević DN, Zarić SD Abstract Important interactions: The interactions between two benzene molecules in the parallel orientation are studied by means of crystallographic and computational methods. The results may have interesting applications in the study of systems containing aromatic molecules, including biomolecules and pharmaceuticals. The figure shows the minimum of a benzene dimer at a large offset (optimized geometry with an interaction energy of 2.01 kcal mol(-1) ). PMID: 22106051 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5439919 Tue, 22 Nov 2011 05:00:00 +0100 5439919 http://www.medworm.com/index.php?rid=5439920&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22106046%26dopt%3DAbstract Authors: Lang XF, Yin PG, You TT, Guo L Abstract Chemical enhancement in surface-enhanced Raman scattering (SERS) of pyrazine adsorbed on Au-Pd nanoclusters is investigated by using density functional theory. Changing Pd content in the bimetallic clusters enables modulation of the direct chemical interactions between the pyrazine and the clusters. The magnitude of chemical enhancement is correlated well with the induced polarizability for the complexes with low Pd content, which fails for the complexes with high Pd content. Furthermore, the dependence of chemical enhancement on cluster size and coupling is also described by the induced polarizability. Additionally, the chemical enhancement in the cluster-molecule-cluster junction is found to account for as much as 10(3) , which sug... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5439920 Mon, 21 Nov 2011 05:00:00 +0100 5439920 http://www.medworm.com/index.php?rid=5419460&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22084003%26dopt%3DAbstract Authors: PMID: 22084003 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419460 Fri, 18 Nov 2011 05:00:00 +0100 5419460 http://www.medworm.com/index.php?rid=5419459&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22084004%26dopt%3DAbstract Authors: PMID: 22084004 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419459 Fri, 18 Nov 2011 05:00:00 +0100 5419459 http://www.medworm.com/index.php?rid=5419456&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22086719%26dopt%3DAbstract Authors: Lattach Y, Garnier F, Remita S Abstract Sensitive layers based on conducting homopolymer [poly(3,4-ethylenedioxythiophene), denoted PEDOT] and copolymers [molecularly imprinted and non-imprinted poly(EDOT-co-3-thiophene acetic acid), denoted MICP and NICP, respectively] are electrosynthesized on gold substrates and used for the electrochemical detection of atrazine. These layers are characterized by cyclic voltammetry, ATR-FTIR spectroscopy, optical profilemetry, and AFM microscopy in order to study the effect of the chemical functionalities and of the structural properties of these conducting polymers on the physical chemistry of the interaction with atrazine targets and with the aim to improve the sensitivity of the recognition process. In particular, due to the presence... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419456 Tue, 15 Nov 2011 05:00:00 +0100 5419456 http://www.medworm.com/index.php?rid=5419455&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22086755%26dopt%3DAbstract Authors: Kahr B, Arteaga O Abstract The year 2011 is the bicentennial of François Arago's discovery of optical rotation. The immediate usurpation of the study of optical activity by Jean-Baptiste Biot led to the first well-known judgments of the arrangements of atoms in space. Scientists are less aware that Arago achieved something far greater than his contributions to optics, by signing the 1848 decree that abolished slavery throughout the French Empire. Opposing attitudes of Arago and Biot toward abolition, foreshadowed in their early rift over optical rotation, were surprisingly exposed in mid-century developments in chiroptics. As shown in a recent book by Levitt, Arago sought a reinvention of the whole colonial plantation system consistent with Republican principles, while Bi... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419455 Tue, 15 Nov 2011 05:00:00 +0100 5419455 http://www.medworm.com/index.php?rid=5419454&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22086764%26dopt%3DAbstract Authors: Fan C, Hsiang JC, Dickson RM Abstract Fluorescence modulation offers the opportunity to detect low-concentration fluorophore signals within high background. Applicable from the single-molecule to bulk levels, we demonstrate long-wavelength optical depopulation of dark states that otherwise limit Cy5 fluorescence intensity. By modulated excitation of a long-wavelength Cy5 transient absorption, we dynamically modulate Cy5 emission. The frequency dependence enables specification of the dark-state timescales enabling optical-demodulation-based signal recovery from high background. These dual-laser illumination schemes for high-sensitivity fluorescence-signal recovery easily improve signal-to-noise ratios by well over an order of magnitude, largely by discrimination against bac... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419454 Tue, 15 Nov 2011 05:00:00 +0100 5419454 http://www.medworm.com/index.php?rid=5419458&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22084023%26dopt%3DAbstract Authors: Greco C, Bruschi M, Fantucci P, Ryde U, De Gioia L Abstract A QM/MM investigation of the active-ready (H(ox) ) form of [FeFe]-hydrogenase from D. desulfuricans, in which the electronic properties of all Fe-S clusters (H, F and F') have been simultaneously described using DFT, was carried out with the aim of disclosing a possible interplay between the H-cluster and the accessory iron-sulfur clusters in the initial steps of the catalytic process leading to H(2) formation. It turned out that one-electron addition to the active-ready form leads to reduction of the F'-cluster and not of the H-cluster. Protonation of the H-cluster in H(ox) is unlikely, and in any case it would not trigger electron transfer from the accessory Fe(4) S(4) clusters to the active site. Instead, one-e... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419458 Mon, 14 Nov 2011 05:00:00 +0100 5419458 http://www.medworm.com/index.php?rid=5419457&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22084029%26dopt%3DAbstract Authors: Winkler R, Berger R, Manca M, Hulliger J, Weber E, Loi MA, Botta C PMID: 22084029 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419457 Mon, 14 Nov 2011 05:00:00 +0100 5419457 http://www.medworm.com/index.php?rid=5419464&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22076907%26dopt%3DAbstract Authors: Kokalj A, Kovačević N, Peljhan S, Finšgar M, Lesar A, Milošev I Abstract The gas-phase adsorption of 1,2,3-triazole, benzotriazole, and naphthotriazole-considered as corrosion inhibitors-on copper surfaces was studied and characterized using density functional theory (DFT) calculations. We find that the molecule-surface bond strength increases with increasing molecular size, thus following the sequence: triazole<benzotriazole<naphthotriazole. This trend is explained in terms of molecular electronegativity and chemical hardness, which decrease monotonously as the molecular size increases. While the electronegativity of triazole is almost degenerate with the work function of Cu(111) surface, the electronegativity of larger acenotriazoles is smaller. The difference ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419464 Fri, 11 Nov 2011 05:00:00 +0100 5419464 http://www.medworm.com/index.php?rid=5419463&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22076916%26dopt%3DAbstract Authors: Pathak B, Pradhan K, Hussain T, Ahuja R, Jena P Abstract Using density functional theory, the generalized gradient approximation for the exchange-correlation potential and Møller-Plesset perturbation theory we study the hydrogen uptake of Li- and Mg-doped boranes. Specifically, we calculate the structures and binding energies of hydrogen molecules sequentially attached to LiB(6) H(7) , LiB(12) H(13) , Li(2) B(6) H(6) , Li(2) B(12) H(12,) MgB(6) H(6) , and MgB(12) H(12) . Up to three H(2) molecules can be bound quasi-molecularly to each of the metal cations with binding energies per H(2) molecule ranging between 0.07 eV and 0.27 eV. The corresponding gravimetric densities lie in the range of 3.49 to 12 wt %, not counting the H atoms bound chemically to the B atom... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419463 Fri, 11 Nov 2011 05:00:00 +0100 5419463 http://www.medworm.com/index.php?rid=5419462&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22076930%26dopt%3DAbstract Authors: Saue T PMID: 22076930 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419462 Fri, 11 Nov 2011 05:00:00 +0100 5419462 http://www.medworm.com/index.php?rid=5419461&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22076937%26dopt%3DAbstract Authors: Thomas A, Krishna Chaitanya G, Bhanuprakash K, Krishna Prasad KM Abstract Keeping in view the possible applications of singlet open-shell molecules as semiconductors, non-classical derivatives of the heterocyclic rings benzobis(thiadiazole) (BBT) and its positional isomer thiadiazolothienopyrazine (TTP) are characterized using DFT methodologies. M06-2X, B3LYP and BHandHLYP functionals were used to optimize the geometries and estimate the vertical transition energies. It is observed that unlike the BHandHLYP functional (50 % exchange), which gives rise to spin-contaminated solutions for all molecules in the series, M06-2X (54 % exchange) affords a wavefunction either with no instability or negligible instability for most of the molecules. The results are compared with t... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419461 Fri, 11 Nov 2011 05:00:00 +0100 5419461 http://www.medworm.com/index.php?rid=5419466&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22069242%26dopt%3DAbstract Authors: Lutz S, Meuwly M Abstract The photodissociation dynamics of small molecules in the gas and condensed phase is an important source of information for better characterizing intermolecular interactions. Herein, classical molecular dynamics simulations with provisions to follow reactive processes between different electronic states are used to probe the wavelength dependence of product state distributions after laser excitation of ClCN. It is found that the maximum of the rotational excitation distribution P(j) of the CN product shifts to lower j-values with increasing wavelength and the width of the distribution narrows. Both observations are in accord with earlier experiments and provide improvements over previous theoretical treatments of the process with the same interacti... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419466 Wed, 09 Nov 2011 05:00:00 +0100 5419466 http://www.medworm.com/index.php?rid=5419468&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22069236%26dopt%3DAbstract Authors: Kohler FT, Morain B, Weiß A, Laurin M, Libuda J, Wagner V, Melcher BU, Wang X, Meyer K, Wasserscheid P Abstract The influence of confinement on the ionic liquid crystal (ILC) [C(18) C(1) Im][OTf] is studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The ILC studied is supported on Si-based powders and glasses with pore sizes ranging from 11 to 50 nm. The temperature of the solid-to-liquid-crystalline phase transition seems mostly unaffected by the confinement, whereas the temperature of the liquid-crystalline-to-liquid phase transition is depressed for smaller pore sizes. A contact layer with a thickness in the order of 2 nm is identified. The contact laye... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419468 Tue, 08 Nov 2011 05:00:00 +0100 5419468 http://www.medworm.com/index.php?rid=5419467&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22069239%26dopt%3DAbstract Authors: Domin D, Benoit DM Abstract Four common parametrisations of spin-component-scaled second-order Møller-Plesset (MP2) theory are benchmarked by calculating the anharmonic vibrational frequencies of a test suite consisting of eighteen diatomic and five small molecules. Of the four methods, the scaled opposite-spin MP2 (SOS-MP2), the variable-scaling opposite-spin MP2 (VOS-MP2) and the spin-component-scaled MP2 (SCS-MP2) methods perform statistically better than standard MP2 theory, while the spin-component scaled for nucleic bases MP2 (SCSN-MP2) performs worse. Vibrations of closed-shell diatomic molecules are slightly more accurately described by the SOS-MP2 method of Head-Gordon (ε(MAD) =51 cm(-1) ) than the SCS-MP2 method of Grimme (ε(MAD) =61 cm(-1) ) or the size-c... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419467 Tue, 08 Nov 2011 05:00:00 +0100 5419467 http://www.medworm.com/index.php?rid=5419465&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22069245%26dopt%3DAbstract Authors: Zhang X, Sun D, Sue HJ, Nishimura R PMID: 22069245 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419465 Tue, 08 Nov 2011 05:00:00 +0100 5419465 http://www.medworm.com/index.php?rid=5419485&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22065460%26dopt%3DAbstract Authors: Sun L, Zhang S, Wang X, Sun XW, Ong DY, Wang X, Zhao D Abstract Anodic formation of titania nanowires has been interpreted using a bamboo-splitting model; however, a number of phenomena are difficult to explain with this model. Herein, transition from nanotubes to nanowires is investigated by varying the anodizing conditions. The results indicate that the transition requires a large number of hydrogen ions to reduce the passivated area of tube walls, and therefore can be observed only in an intermediate chemical dissolution environment. Accordingly, a model in terms of stretching and splitting is proposed to interpret the transition process. The model provides a basis to suppress the nanowires with surface treatments before anodization and to clear the nanowires with an ul... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419485 Mon, 07 Nov 2011 05:00:00 +0100 5419485 http://www.medworm.com/index.php?rid=5419469&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22065478%26dopt%3DAbstract Authors: Younker JM, Beste A, Buchanan AC Abstract The biopolymer lignin is a potential source of valuable chemicals. Phenethyl phenyl ether (PPE) is representative of the dominant β-O-4 ether linkage. DFT is used to calculate the Boltzmann-weighted carbon-oxygen and carbon-carbon bond dissociation enthalpies (BDEs) of substituted PPE. These values are important for understanding lignin decomposition. Exclusion of all conformers that have distributions of less than 5 % at 298 K impacts the BDE by less than 1 kcal mol(-1) . We find that aliphatic hydroxyl/methylhydroxyl substituents introduce only small changes to the BDEs (0-3 kcal mol(-1) ). Substitution on the phenyl ring at the ortho position substantially lowers the CO BDE, except in combination with the hydroxy... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5419469 Mon, 07 Nov 2011 05:00:00 +0100 5419469 http://www.medworm.com/index.php?rid=5379575&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22052820%26dopt%3DAbstract Authors: Heinz P, Hindelang K, Golosova A, Papadakis CM, Rieger B Abstract Silicon-containing materials which possess the ability to form mesophases are promising systems for applications in the fields of electro-optical devices, nonlinear optics, and information storage media. In this work, the formation of supramolecular assemblies of a series of low molecular weight siloxane-containing mesogens is presented. Besides a novel synthesis route via Ru(II) -catalyzed hydrosilylation of phenyl acetylene derivatives, mesophase characterization by modern analysis techniques is performed. As linker groups, leading to bi- and tetramesogens, linear disiloxane and cyclic tetrasiloxane are utilized. In the resulting class of materials, high thermal stability, induced by the formation of layer... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379575 Thu, 03 Nov 2011 04:00:00 +0100 5379575 http://www.medworm.com/index.php?rid=5379574&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22052831%26dopt%3DAbstract Authors: Oyeyemi VB, Pavone M, Carter EA Abstract Quantum chemistry has become one of the most reliable tools for characterizing the thermochemical underpinnings of reactions, such as bond dissociation energies (BDEs). The accurate prediction of these particular properties (BDEs) are challenging for ab initio methods based on perturbative corrections or coupled cluster expansions of the single-determinant Hartree-Fock wave function: the processes of bond breaking and forming are inherently multi-configurational and require an accurate description of non-dynamical electron correlation. To this end, we present a systematic ab initio approach for computing BDEs that is based on three components: 1) multi-reference single and double excitation configuration interaction (MRSDCI) for t... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379574 Thu, 03 Nov 2011 04:00:00 +0100 5379574 http://www.medworm.com/index.php?rid=5379573&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22052844%26dopt%3DAbstract Authors: Cebolla VL, Mateos E, Garriga R, Jarne C, Membrado L, Cossío FP, Gálvez EM, Matt M, Delgado-Camón A Abstract Changes in fluorescence emission due to non-covalent analyte-fluorophore interactions in silica gel plates are studied and used as a general detection procedure for thin-layer chromatography (TLC). The presence of the analyte modifies the microenvironment of the fluorophore and thus changes the balance between radiative (k(r) ) and non-radiative (k(nr) ) emission constants. A model is proposed for analyte-fluorophore induced electrostatic interactions, which depend on analyte polarizability and are responsible for fluorescence enhancements. As consequence of these induced interactions, the analyte creates an apolar environment that prevents non-fluorescent decay ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379573 Thu, 03 Nov 2011 04:00:00 +0100 5379573 http://www.medworm.com/index.php?rid=5379572&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22052852%26dopt%3DAbstract Authors: Jacob C Abstract Raman optical activity (ROA) spectroscopy is a promising analytical method for studying the structure and conformation of polypeptides and proteins in solution. However, the structural information obtained from such vibrational spectra is only indirect and theoretical studies are often necessary to identify how the structure determines the observed spectra. One particular target is the identification and discrimination of different helical secondary structure elements. Herein, a theoretical investigation of the ROA spectra of a series of 3(10) -helical polypeptides is presented. In particular, the effect of chain length, C(α) -substitution pattern, the introduction of larger aliphatic side chains, and the variation of their conformation on the ROA spectra... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379572 Thu, 03 Nov 2011 04:00:00 +0100 5379572 http://www.medworm.com/index.php?rid=5379576&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22045646%26dopt%3DAbstract Authors: Choutko A, van Gunsteren WF, Hünenberger PH Abstract The modulation of the properties of lipid membranes by polyhydroxylated cosolutes such as sugars is a phenomenon of considerable biological, technological and medicinal relevance. A few years ago, we proposed the sugar-like mechanism-binding driven by the release of water molecules-as an attempt to rationalize the preferential affinity of carbohydrate molecules compared to water molecules for the surface of lipid bilayers, which is presumably related to the bioprotective action of these compounds. The goal herein is to gain a better understanding of the driving force underlying this mechanism, in terms of specific interactions or effects, as well as in terms of the energy-entropy partitioning. This is done in the simple... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379576 Wed, 02 Nov 2011 04:00:00 +0100 5379576 http://www.medworm.com/index.php?rid=5379580&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22038873%26dopt%3DAbstract We present the first results of electron magnetic resonance (EMR) and Mössbauer spectroscopy studies of γ-Fe(2) O(3) nanoparticles (NPs) incorporated into liquid-crystalline, second-generation dendrimers. The mean size of NPs formed in the dendrimers was around 2.5 nm. A temperature-driven transition from superparamagnetic to ferrimagnetic resonance was observed for the sample. Low-temperature blocking of the NP magnetic moments has been clearly evidenced in the integrated EMR line intensity and the blocking temperature was about 60 K. The physical parameters of magnetic NPs (magnetic moment, effective magnetic anisotropy) have been determined from analyses of the EMR data. The effective magnetic anisotropy constant is enhanced relative to bulk γ-Fe(2) O(3) and this enhanced value i... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379580 Fri, 28 Oct 2011 04:00:00 +0100 5379580 http://www.medworm.com/index.php?rid=5379579&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22038881%26dopt%3DAbstract Authors: Casanova D Abstract The key elements arising from different linkers between donor (D) and acceptor (A) fragments in D-π-A organic dyes are computationally studied. Taking triarylamine and the cyanoacrylic acid fragments as donor and acceptor units, respectively, the role of the different separators is computationally explored by means of optimized geometries, frontier molecular orbitals, static polarizabilities and hyperpolarizabilities, excitation energies to the lowest excited singlet, the charge-transfer character of the transition, and simulated absorption spectra. The results are compared to two closely related sets of linkers. Electronic-structure calculations on the studied organic dyes are performed with the CIS(D) wave function based method and time-dependent den... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379579 Fri, 28 Oct 2011 04:00:00 +0100 5379579 http://www.medworm.com/index.php?rid=5379578&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22038888%26dopt%3DAbstract Authors: Korth M Abstract The accurate description of hydrogen-bond interactions is of vital importance for the computational modeling of biological systems. Standard force field (FF) as well as semiempirical quantum mechanical (SQM) methods are now known to have considerable problems with the accurate description of hydrogen bonds. It was found that the performance of SQM methods can be greatly improved with empirical hydrogen-bond correction terms. In the first part of this work we review the improvements developed during the recent revival of dedicated hydrogen-bond terms, also in the light of earlier FF-related work. The second part presents new findings connected to open questions in this field, namely, a study on the importance of angular and torsional information, a scheme h... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379578 Fri, 28 Oct 2011 04:00:00 +0100 5379578 http://www.medworm.com/index.php?rid=5379577&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22038901%26dopt%3DAbstract Authors: Paulsen H, Trautwein AX, Wegner P, Schmidt C, Chumakov AI, Schünemann V Abstract Nuclear resonant vibrational spectra of the reduced and oxidized form of a mutant of rubredoxin from Pyrococcus abyssii were measured and are compared with simulated spectra that were calculated by a combined quantum mechanics (QM) and molecular mechanics (MM) method. Density functional theory was used for the QM level. Calculations were performed for different models of rubredoxin. Realistic spectra were simulated with reduced models that include at least the iron center, the four cysteins coordinating it, and the residues connected to the cysteins together with a QM layer that comprises the first two coordination shells of the iron center. Larger QM layers did not lead to significant change... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379577 Fri, 28 Oct 2011 04:00:00 +0100 5379577 http://www.medworm.com/index.php?rid=5379581&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22034210%26dopt%3DAbstract Authors: Perlt E, Friedrich J, von Domaros M, Kirchner B Abstract The investigation of liquid phases by means of accurate electronic structure methods is a demanding task due to the high computational effort. We applied second-order Møller-Plesset perturbation theory and high-level quantum chemical calculations using the coupled-cluster method with single, double and perturbative triple excitations in combination with Dunnings correlation-consistent basis sets up to quintuple ζ quality. Based on these calculations, we extrapolated the correlation energy to the basis set limit in order to improve the results even further. For comparison to the correlated electronic structure methods, density functional calculations employing different functionals are presented as well. The investi... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379581 Thu, 27 Oct 2011 04:00:00 +0100 5379581 http://www.medworm.com/index.php?rid=5379584&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22028299%26dopt%3DAbstract Authors: Abbate S, Lebon F, Lepri S, Longhi G, Gangemi R, Spizzichino S, Bellachioma G, Ruzziconi R PMID: 22028299 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379584 Wed, 26 Oct 2011 04:00:00 +0100 5379584 http://www.medworm.com/index.php?rid=5379583&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22028307%26dopt%3DAbstract Authors: Tsai PY, Lin KC Abstract The behavior of Λ-doublet resolved rotational energy transfer (RET) by Ar collisions within the SH(X(2) Π, v''=0) state is characterized. The matrix elements of terms in the interaction potential responsible for interference effects are calculated to explain the propensity rules for collision-induced transitions within and between spin-orbit manifolds. In this manner, the physical mechanisms responsible for the F(1) -F(1) , F(2) -F(2) , and F(1) -F(2) transitions may be reasonably identified. As collision energy increases, the propensity for collisional population of the final e or f level is replaced by the e/f-conserving propensity. Such a change in propensity rule can be predicted in terms of energy sudden approximation at high J limit for the... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379583 Wed, 26 Oct 2011 04:00:00 +0100 5379583 http://www.medworm.com/index.php?rid=5379582&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22028312%26dopt%3DAbstract Authors: Vitzthum V, Borcard F, Jannin S, Morin M, Miéville P, Caporini MA, Sienkiewicz A, Gerber-Lemaire S, Bodenhausen G PMID: 22028312 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379582 Wed, 26 Oct 2011 04:00:00 +0100 5379582 http://www.medworm.com/index.php?rid=5379587&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22025448%26dopt%3DAbstract Authors: Perissinotto S, Garbugli M, Fazzi D, Bertarelli C, Carvelli M, Srimath Kandada AR, Yue Z, Wong KS, Lanzani G Abstract A novel system for the modulation of amplified emission based on a polyfluorene/diarylethene (namely F8BT/DTP) blend is shown. The high sensitivity of amplified spontaneous emission (ASE) is exploited to achieve efficient emission modulation with a low-intensity control signal. Modulation is then characterized by photoluminescence (PL) lifetime measurements, photocurrent experiments, and density functional theory calculations. This system can also act as a photocurrent switch based on the same principle. This technique may represent a useful tool for fluorescence quenching and sensing as well as find application in organic photonics. PMID: 22025448 [Pub... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379587 Mon, 24 Oct 2011 04:00:00 +0100 5379587 http://www.medworm.com/index.php?rid=5379586&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22025451%26dopt%3DAbstract Authors: Lu J, Dai Y, Guo M, Wei W, Ma Y, Han S, Huang B Abstract As an excellent bandgap-engineering material, the Cd(1-x) Zn(x) S solid solution, is found to be an efficient visible light response photocatalyst for water splitting, but few theoretical studies have been performed on it. A better characterization of the composition dependence of the physical and optical properties of this material and a thorough understanding of the bandgap-variation mechanism are necessary to optimize the design of high-efficience photocatalysts. In order to get an insight into these problems, we systematically investigated the crystal structure, the phase stability, and the electronic structures of the Cd(1-x) Zn(x) S solid solution by means of density functional theory calculations. The most ene... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379586 Mon, 24 Oct 2011 04:00:00 +0100 5379586 http://www.medworm.com/index.php?rid=5379585&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22025455%26dopt%3DAbstract Authors: Islam MM, Bredow T, Gerson A Abstract The electronic properties of vanadium-doped rutile TiO(2) are investigated theoretically with a Hartree-Fock/DFT hybrid approach. The most common oxidation states (V(2+) , V(3+) , V(4+) , and V(5+) ) in different spin states are investigated and their relative stability is calculated. The most stable spin states are quartet, quintet, doublet, and singlet for V(2+) , V(3+) , V(4+) , and V(5+) doping, respectively. By comparing the formation energy with respect to the parent oxides and gas-phase oxygen (ΔE), we conclude that V(4+) (ΔE=145.3 kJ mol(-1) ) is the most likely oxidation state for vanadium doping with the possibility of V(5+) doping (ΔE=283.5 kJ mol(-1) ). The energetic and electronic properties are converged with d... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5379585 Mon, 24 Oct 2011 04:00:00 +0100 5379585 http://www.medworm.com/index.php?rid=5326388&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21990136%26dopt%3DAbstract Authors: Lanza G, Chiacchio U, Motta S, Pellegrino S, Broggini G PMID: 21990136 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326388 Wed, 19 Oct 2011 05:45:08 +0100 5326388 http://www.medworm.com/index.php?rid=5326374&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002889%26dopt%3DAbstract Authors: PMID: 22002889 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326374 Wed, 19 Oct 2011 05:42:06 +0100 5326374 http://www.medworm.com/index.php?rid=5326373&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002890%26dopt%3DAbstract Authors: Naya S, Inoue A, Tada H PMID: 22002890 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326373 Wed, 19 Oct 2011 05:41:55 +0100 5326373 http://www.medworm.com/index.php?rid=5326372&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002891%26dopt%3DAbstract Authors: Santhosh K, Patra S, Soumya S, Khara DC, Samanta A Abstract Fluorescence quenching of CdS quantum dots (QDs) by 4-azetidinyl-7-nitrobenz-2-oxa-1,3-diazole (NBD), where the two quenching partners satisfy the spectral overlap criterion necessary for Förster resonance energy transfer (FRET), is studied by steady-state and time-resolved fluorescence techniques. The fluorescence quenching of the QDs is accompanied by an enhancement of the acceptor fluorescence and a reduction of the average fluorescence lifetime of the donor. Even though these observations are suggestive of a dynamic energy transfer process, it is shown that the quenching actually proceeds through a static interaction between the quenching partners and is probably mediated by charge-transfer interactions. The ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326372 Wed, 19 Oct 2011 05:41:43 +0100 5326372 http://www.medworm.com/index.php?rid=5326371&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002892%26dopt%3DAbstract Authors: Al Zoubi M, Al-Salman R, El Abedin SZ, Li Y, Endres F Abstract The electrochemical synthesis of gallium nanostructures in an ionic liquid is presented. Gallium nanowires and macroporous structures were synthesized by the template-assisted electrodeposition in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py(1,4) ]TFSA) containing GaCl(3) as the precursor. Track-etched polycarbonate membranes with an average pore diameter of 90 nm and a thickness of 21 μm were used as templates for the nanowire synthesis. Ga nanowires with a length of more than 4 μm and an average diameter corresponding to that of the template's pores were easily obtained by this method. Macroporous structures with an average pore diameter of 600 nm were obtained by th... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326371 Wed, 19 Oct 2011 05:41:31 +0100 5326371 http://www.medworm.com/index.php?rid=5326370&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002893%26dopt%3DAbstract We present improved virtual orbital (IVO) complete active space (CAS) configuration interaction (IVO-CASCI) and IVO-CASCI-based multireference Møller-Plesset perturbation theory (MRMPPT) calculations with an aim to elucidate the electronic structure of tetramethyleneethane (TME) in its lowest singlet and triplet state and to quantify their order and extent of splitting. The potential surfaces of singlet and triplet states for the twisting of TME are also studied. We found that the triplet state is higher in energy than the singlet one in the whole range of twisting angles with the energy gap minimum at a twisting angle of about 45°. Harmonic vibrational frequencies of TME have also been calculated for both the states. We also report the ground to first excited triplet state transition en... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326370 Wed, 19 Oct 2011 05:41:20 +0100 5326370 http://www.medworm.com/index.php?rid=5326369&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002894%26dopt%3DAbstract Authors: Pähler M, Schuhmann W, Gratzl M Abstract Scanning electrochemical microscopy visualizes concentration profiles. To determine the location of the probe relative to topographical features of the substrate, knowledge of the probe-to-sample distance at each probe position is required. The use of electrochemical impedance spectroscopy for obtaining information on the substrate-to-probe distance and on the concentration of interest using the electrochemical probe alone is suggested. By tuning the frequencies of interrogation, the probe-to-substrate distance can be derived followed by interrogation of processes that carry information on concentration at lower frequencies. These processes may include charge-transfer relaxation, diffusional relaxation at the electrode, and open-ci... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326369 Wed, 19 Oct 2011 05:41:10 +0100 5326369 http://www.medworm.com/index.php?rid=5326368&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002895%26dopt%3DAbstract Authors: Kozub BR, Henstridge MC, Batchelor-McAuley C, Compton RG Abstract An edge plane pyrolitic graphite (EPPG) electrode was modified by electrochemical reduction of anthraquinone-2-diazonium tetrafluoroborate (AQ2-N(2) (+) BF(4) (-) ), giving an EPPG-AQ2-modified electrode of a surface coverage below a monolayer. Cyclic voltammograms simulated using Marcus-Hush theory for 2e(-) process assuming a uniform surface gave unrealistically low values of reorganisation energies, λ, for both electron transfer steps. Subsequently, two models of surface inhomogeneity based on Marcus-Hush theory were investigated: a distribution of formal potentials, E', and a distribution of electron tunneling distances, r(0) . The simulation of cyclic voltammograms involving the distributio... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326368 Wed, 19 Oct 2011 05:40:59 +0100 5326368 http://www.medworm.com/index.php?rid=5326367&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002896%26dopt%3DAbstract Authors: PMID: 22002896 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326367 Wed, 19 Oct 2011 05:40:47 +0100 5326367 http://www.medworm.com/index.php?rid=5326366&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002909%26dopt%3DAbstract Authors: O'Byrne JP, Li Z, Jones SL, Fleming PG, Larsson JA, Morris MA, Holmes JD Abstract Nitrogen-doped bamboo-structured carbon nanotubes have been successfully grown using a series of cobalt/molybdenum catalysts. The morphology and structure of the nanotubes were analysed by transmission electron microscopy and Raman spectroscopy. The level of nitrogen doping, as determined by X-ray photoelectron spectroscopy, was found to range between 0.5 to 2.5 at. %. The growth of bamboo-structured nanotubes in the presence of nitrogen, in preference to single-walled and multi-walled nanotubes, was due to the greater binding energy of nitrogen for cobalt in the catalyst compared to the binding strength of carbon to cobalt, as determined by density functional theory. PMID: 22002909 [Pu... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326366 Fri, 14 Oct 2011 04:00:00 +0100 5326366 http://www.medworm.com/index.php?rid=5326365&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002913%26dopt%3DAbstract Authors: Zeng Y, Zhu M, Meng L, Zheng S Abstract The intermolecular interactions in C(6) H(6) ⋅⋅⋅LiX (X=OH, NH(2) , F, Cl, Br, NC, CN) complexes are investigated by using second-order Møller-Plesset perturbation theory (MP2) calculations and quantum theory of "atoms in molecules" (QTAIM) studies, and the role of π electrons is studied in the formation of these benzene-containing lithium-bonded complexes. The molecular electrostatic potentials of benzene and LiX determine the geometries of the lithium-bonded complexes. The electron densities at the lithium bond critical points in the πC(6) H(6) ⋅⋅⋅LiX complexes are obviously stronger than those in the σC(6) H(6) ⋅⋅⋅LiX complexes, which indicates that the intermolecular interactions in the C(6) H(6) ⋅⋅⋅L... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326365 Fri, 14 Oct 2011 04:00:00 +0100 5326365 http://www.medworm.com/index.php?rid=5326364&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002917%26dopt%3DAbstract Authors: Lingscheid Y, Arenz S, Giernoth R Abstract (19) F,(1) H HOESY experiments with three ionic liquids ([bmim]BF(4) , [bmim]PF(6) and [emim]BF(4) ) were run in two different solvents and neat. The results give preferred probabilities of presence and enable us to systematically study interactions between the cations and the anions in the ionic liquid phase by NMR spectroscopy. The influence of different solvents and of the presence or absence of air (i.e. oxygen) is discussed. This enabled us to substantially speed up the NMR experiments and to develop a more precise method for the investigation of liquid-phase structures in ionic liquids. PMID: 22002917 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326364 Fri, 14 Oct 2011 04:00:00 +0100 5326364 http://www.medworm.com/index.php?rid=5326379&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21997793%26dopt%3DAbstract In this study, the surface-enhanced Raman scattering (SERS) technique is used to characterize the conformational changes of a protein (lysozyme) adsorbed on tailored flat gold substrates with different chemistries. Two such substrates are formed by self-assembly of octadecanethiol and thiolated PEG on gold chips (Au-C18 and Au-PEG). Preliminary results reveal that, compared to the hydrophobic Au-C18 surface, the hydrophilic Au-PEG surface has much smaller effect on the conformation of lysozyme in aqueous solution, which thereby keeps its high bioactivity. The conformational changes of lysozyme adsorbed on material surfaces with different chemistries are well correlated with changes in its bioactivity. PMID: 21997793 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326379 Thu, 13 Oct 2011 04:00:00 +0100 5326379 http://www.medworm.com/index.php?rid=5326378&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21997842%26dopt%3DAbstract Authors: Munusamy E, Sedlak R, Hobza P Abstract The structure and stabilization energies of benzene (and methylated benzenes)⋅⋅⋅X(2) (X=F, Cl, Br, N) complexes were investigated by performing CCSD(T)/complete basis set limit and density functional theory/symmetry-adapted perturbation theory (DFT-SAPT) calculations. The global minimum of the benzene⋅⋅⋅dihalogen complexes corresponds to the T-shaped structure, whereas that of benzene⋅⋅⋅dinitrogen corresponds to the sandwich one. The different binding motifs of these complexes arise from the different quadrupole moments of dihalogens and dinitrogen. The different sign of the quadrupole moments of these diatomics is explained based on the electrostatic potential (ESP). Whereas all dihalogens, including difluorine, pos... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326378 Thu, 13 Oct 2011 04:00:00 +0100 5326378 http://www.medworm.com/index.php?rid=5326377&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21997869%26dopt%3DAbstract Authors: Yang Y, Koo S, Xia Y, Venkatraman S, Neu B Abstract Red blood cell (RBC) adhesion to the endothelium is usually insignificant. However, an enhanced adhesion can be observed in various pathological conditions such as diabetes mellitus or sickle cell disease, which is often accompanied by elevated levels of pro-adhesive plasma proteins such as fibrinogen. In the past, these proteins have only been considered to act as ligands, cross-linking the corresponding receptors on adjacent cells, but the detailed underlying mechanism often remained obscure. This work demonstrates that the presence of non-adsorbing polymers in plasma can also enhance the adhesion efficiency of RBCs to endothelial cells (ECs) through depletion interaction. Furthermore, adhesion of RBCs to ECs may be lik... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326377 Thu, 13 Oct 2011 04:00:00 +0100 5326377 http://www.medworm.com/index.php?rid=5326376&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21997887%26dopt%3DAbstract Authors: Navizet I, Liu YJ, Ferré N, Roca-Sanjuán D, Lindh R Abstract Firefly luciferase is one of the most studied bioluminescent systems, both theoretically and experimentally. Herein we review the current understanding of the bioluminescent process from a chemical functionality perspective based on those investigations. Three key components are emphasized: the chemiluminophore, the electron-donating fragment, and how these are affected by the substrate-enzyme interaction. The understanding is based on details of how the peroxide OO bond supports the production of electronically excited products and how the charge-transfer (CT) mechanism, with the aid of an electron-donating group, lowers the activation barrier to support a reaction occurs in living organisms. For the ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326376 Thu, 13 Oct 2011 04:00:00 +0100 5326376 http://www.medworm.com/index.php?rid=5326375&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21997901%26dopt%3DAbstract Authors: Xu J, Sahu S, Cao L, Anilkumar P, Tackett KN, Qian H, Bunker CE, Guliants EA, Parenzan A, Sun YP Abstract Carbon nanomaterials have generated a tremendous amount of attention in the scientific community. While most of the research and development efforts have been on fullerenes, carbon nanotubes, and graphene sheets, carbon nanoparticles (which are often considered as impurities or unwanted complications in the other carbon nanomaterials) have recently emerged as a unique class of highly fluorescent nano-dots. However, little or no attention has been paid to potential uses of carbon nanoparticles as chromophores in photochemical reactions or for photon harvesting and photoconversion in general. In the study reported herein we demonstrate the chromophore-equivalent function... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326375 Thu, 13 Oct 2011 04:00:00 +0100 5326375 http://www.medworm.com/index.php?rid=5326383&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21994161%26dopt%3DAbstract Authors: Amor N, Hamilton K, Küppers M, Steinseifer U, Appelt S, Blümich B, Schmitz-Rode T Abstract Magnetic resonance of hyperpolarized (129) Xe has found a wide field of applications in the analysis of biologically relevant fluids. Recently, it has been shown that the dissolution of hyperpolarized gas into the fluid via hollow-fiber membranes leads to bubble-free (129) Xe augmentation, and thus to an enhanced signal. In addition, hollow-fiber membranes permit a continuous operation mode. Herein, a quantitative magnetic resonance imaging and spectroscopy analysis of a customized hollow-fiber membrane module is presented. Different commercial hollow-fiber membrane types are compared with regard to their (129) Xe dissolution efficiency into porcine blood, its constituents, and oth... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326383 Wed, 12 Oct 2011 04:00:00 +0100 5326383 http://www.medworm.com/index.php?rid=5326382&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21994177%26dopt%3DAbstract Authors: Howard JC, Hammer NI, Tschumper GS Abstract More than 70 unique micro-hydrated structures of pyrimidine, ranging in size from 1 to 7 water molecules, have been characterized with the B3LYP density functional and the 6-311++G(2df,2pd) triple-ζ split-valence basis set. Explicitly correlated MP2-F12 single-point computations were performed on each structure with a correlation consistent triple-ζ basis set to estimate the relative and dissociation energies at the MP2 complete basis set (CBS) limit. Many of these new structures have significantly lower energies than those previously reported (by as much as 12.66 kcal mol(-1) ). For clusters with 1 and 2 water molecules, the MP2-F12 relative and dissociation energies are virtually identical to the corresponding CCSD(T)-F12... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326382 Wed, 12 Oct 2011 04:00:00 +0100 5326382 http://www.medworm.com/index.php?rid=5326381&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21994189%26dopt%3DAbstract Authors: Haag MP, Marti KH, Reiher M Abstract A method is proposed for the automated generation of potential energy surfaces in high dimensions. It combines the existing algorithm for the definition of new energy data points, based on the interpolating moving least-squares algorithm with a simulated annealing procedure. This method is then studied in a haptic quantum chemistry environment that requires a fast evaluation of gradients on a potential energy surface with automatic improvement of its accuracy. As an example we investigate the nitrogen binding pathway in the Schrock dinitrogen fixation complex with this set-up. PMID: 21994189 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326381 Wed, 12 Oct 2011 04:00:00 +0100 5326381 http://www.medworm.com/index.php?rid=5326380&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21994205%26dopt%3DAbstract Authors: Lörtscher E PMID: 21994205 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326380 Wed, 12 Oct 2011 04:00:00 +0100 5326380 http://www.medworm.com/index.php?rid=5326387&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21990147%26dopt%3DAbstract Authors: Wen M, Zhang F, Cheng M, Wu Q, Sun B, Sun Y Abstract Newly designed magnetic FeNi-Pt match-like heterostructured nanorods were synthesized by means of induced growth of FeNi nanorods on Pt nanotips. The proposed synthesis mechanism is corroborated by SEM, TEM, XRD and XPS. The magnetic behavior shows that the magnetic saturation and coercivity are strongly dependent on both the shape and the alloy composition. The saturation magnetizations (Ms) and the coercivity (Hc) of nanorods synthesized are larger than those of nanoparticles because of the relatively large anisotropy of nanorods. Maximum saturation magnetization is obtained for Fe(82) Ni(15) -Pt(3) at 226.6 emu g(-1) , whereas maximum coercivity is obtained for Fe(20) Ni(77) -Pt(3) at 136.8 Oe. Shape-dependent r... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326387 Tue, 11 Oct 2011 04:00:00 +0100 5326387 http://www.medworm.com/index.php?rid=5326386&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21990164%26dopt%3DAbstract Authors: Hasegawa JY, Fujimoto KJ, Nakatsuji H Abstract Depending on protein environment, a single photofunctional chromophore shows a wide variation of photoabsorption/emission energies. This photobiological phenomenon, known as color tuning, is observed in human visual cone pigments, firefly luciferase, and red fluorescent protein. We investigate the origin of color tuning by quantum chemical calculations on the excited states: symmetry-adapted cluster-configuration interaction (SAC-CI) method for excited states and a combined quantum mechanical (QM)/molecular mechanical (MM) method for protein environments. This Minireview summarizes our theoretical studies on the above three systems and explains a common feature of their color-tuning mechanisms. It also discuss the possibility ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326386 Tue, 11 Oct 2011 04:00:00 +0100 5326386 http://www.medworm.com/index.php?rid=5326385&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21990178%26dopt%3DAbstract Authors: Moraes IR, Kalbáč M, Dmitrieva E, Dunsch L PMID: 21990178 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326385 Tue, 11 Oct 2011 04:00:00 +0100 5326385 http://www.medworm.com/index.php?rid=5326384&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21990203%26dopt%3DAbstract Authors: Dabirian A, Kuzminykh Y, Wagner E, Benvenuti G, Rushworth SA, Hoffmann P PMID: 21990203 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326384 Tue, 11 Oct 2011 04:00:00 +0100 5326384 http://www.medworm.com/index.php?rid=5326389&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21984168%26dopt%3DAbstract Authors: Tai TB, Kadłubański P, Roszak S, Majumdar D, Leszczynski J, Nguyen MT Abstract We perform a systematic investigation on small silicon-doped boron clusters B(n) Si (n=1-7) in both neutral and anionic states using density functional (DFT) and coupled-cluster (CCSD(T)) theories. The global minima of these B(n) Si(0/-) clusters are characterized together with their growth mechanisms. The planar structures are dominant for small B(n) Si clusters with n≤5. The B(6) Si molecule represents a geometrical transition with a quasi-planar geometry, and the first 3D global minimum is found for the B(7) Si cluster. The small neutral B(n) Si clusters can be formed by substituting the single boron atom of B(n+1) by silicon. The Si atom prefers the external position of the skeleton and ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5326389 Fri, 07 Oct 2011 04:00:00 +0100 5326389 http://www.medworm.com/index.php?rid=5296723&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21976370%26dopt%3DAbstract Authors: Comesaña-Hermo M, Estivill R, Ciuculescu D, Amiens C, Farle M, Batat P, Jonusauskas G, McClenaghan ND, Lecante P, Tardin C, Mazeres S PMID: 21976370 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5296723 Tue, 04 Oct 2011 04:00:00 +0100 5296723 http://www.medworm.com/index.php?rid=5296722&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21976382%26dopt%3DAbstract Authors: Bottomley A, Ianoul A PMID: 21976382 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5296722 Tue, 04 Oct 2011 04:00:00 +0100 5296722 http://www.medworm.com/index.php?rid=5279211&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21818836%26dopt%3DAbstract New Insights into the Band-Gap Narrowing of (N, P)-Codoped TiO(2) from Hybrid Density Functional Theory Calculations. Chemphyschem. 2011 Oct 4;12(14):2604-8 Authors: Long R, English NJ Abstract The electronic properties of anatase-TiO(2) codoped by N and P at different concentrations have been investigated via generalized Kohn-Sham theory with the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional for exchange-correlation in the context of density functional theory. At high doping concentrations, we find that the high photocatalytic activity of (N, P)-codoped anatase TiO(2) vis-à-vis the N-monodoped case can be rationalized by a double-hole-mediated coupling mechanism [Yin et al., Phys. Rev. Lett. 2011, 106, 066801] via the formation of an effective NP bond. On the other... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279211 Mon, 03 Oct 2011 22:39:55 +0100 5279211 http://www.medworm.com/index.php?rid=5279210&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21826776%26dopt%3DAbstract Effect of PIP(2) on Bilayer Structure and Phase Behavior of DOPC: An X-ray Scattering Study. Chemphyschem. 2011 Oct 4;12(14):2633-40 Authors: Ghosh SK, Aeffner S, Salditt T Abstract Phosphatidylinositol 4,5-bis-phosphate (PIP(2) ) is an important lipid in regulation of several cellular processes, particularly membrane fusion. We use X-ray diffraction from solid-supported multilamellar 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/PIP(2) samples to study changes in bilayer structure and the lyotropic phase behavior induced by physiologically relevant concentrations of PIP(2) . Electron-density profiles reconstructed from X-ray reflectivity measurements indicate that PIP(2) strongly affects structural parameters such as lipid head-group width, bilayer thickness, and lamella... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279210 Mon, 03 Oct 2011 22:39:46 +0100 5279210 http://www.medworm.com/index.php?rid=5279209&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21826777%26dopt%3DAbstract Authors: Srivastava S, Gajbhiye NS Abstract Herein, blue fluorescent carbogenic nanodots (CNDs) with room-temperature ferromagnetism were synthesized by thermal decomposition of organic precursors at different temperatures. Photoluminescence (PL) studies show excitation-wavelength-dependent emission properties and PL excitation (PLE) studies confirm the triplet ground state of carbene at the zigzag edge as the fluorescent center. Room-temperature magnetic studies reveal the ferromagnetic nature of CNDs and temperature-dependent studies show the presence of an antiferromagnetic phase along with a ferromagnetic phase below 50 K. EPR studies reveal the presence of conduction electrons and localized spins with different g factors. Localized spins at zigzag edges are the origin of the u... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279209 Mon, 03 Oct 2011 22:39:36 +0100 5279209 http://www.medworm.com/index.php?rid=5279208&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21826778%26dopt%3DAbstract Authors: Backes C, Bosch S, Mundloch U, Hauke F, Hirsch A PMID: 21826778 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279208 Mon, 03 Oct 2011 22:39:26 +0100 5279208 http://www.medworm.com/index.php?rid=5279207&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21830293%26dopt%3DAbstract Authors: Nothaft M, Höhla S, Nicolet A, Jelezko F, Frühauf N, Pflaum J, Wrachtrup J Abstract Photoluminescence quenching of single dibenzoterrylene (DBT) dye molecules in a polymeric organic light-emitting diode was utilized to analyze the current dynamics at nanometer resolution. The quenching mechanism of single DBT molecules results from an increase in the triplet-state population induced by charge carrier recombination on individual guest molecules. As a consequence of the long triplet-state relaxation time, its population results in a reduced photoluminescence of the dispersed fluorescent dyes. From the decrease in photoluminescence together with photon correlation measurements, we could quantify the local current density and its time-dependent evolution in the vicinity of t... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279207 Mon, 03 Oct 2011 22:39:15 +0100 5279207 http://www.medworm.com/index.php?rid=5279206&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21830294%26dopt%3DAbstract Authors: Murade CU, Subramaniam V, Otto C, Bennink ML PMID: 21830294 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279206 Mon, 03 Oct 2011 22:39:05 +0100 5279206 http://www.medworm.com/index.php?rid=5279204&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21954001%26dopt%3DAbstract Authors: PMID: 21954001 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279204 Mon, 03 Oct 2011 22:37:52 +0100 5279204 http://www.medworm.com/index.php?rid=5279203&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21954002%26dopt%3DAbstract Bridging η(2) -BO in B(2) (BO)(3) (-) and B(3) (BO)(3) (-) Clusters: Boronyl Analogs of Boranes. Chemphyschem. 2011 Oct 4;12(14):2549-53 Authors: Zhai HJ, Guo JC, Li SD, Wang LS Abstract Anion photoelectron spectroscopy and theoretical calculations are combined to probe the structures and chemical bonding of two boron-rich oxide clusters, B(5) O(3) (-) and B(6) O(3) (-) , which are shown to be appropriately formulated as B(2) (BO)(3) (-) and B(3) (BO)(3) (-) , respectively. The anion clusters are found to each possess a bridging η(2) -BO group, as well as two terminal BO groups and are analogs of B(2) H(3) (-) and B(3) H(3) (-) . This finding advances the boronyl chemistry and helps establish the isolobal analogy between bor... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279203 Mon, 03 Oct 2011 22:37:43 +0100 5279203 http://www.medworm.com/index.php?rid=5279202&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21954003%26dopt%3DAbstract Authors: Wyczawska S, Cyganik P, Terfort A, Lievens P PMID: 21954003 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279202 Mon, 03 Oct 2011 22:37:34 +0100 5279202 http://www.medworm.com/index.php?rid=5279201&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21954004%26dopt%3DAbstract Authors: Kunz AP, van Gunsteren WF Abstract A method for conformational Boltzmann sampling of loops in proteins in aqueous solution is presented that is based on adiabatic decoupling molecular dynamics (MD) simulation with temperature or force scaling. To illustrate the enhanced sampling, the loop from residues 33 to 43 in the bovine protein ribonuclease A is adiabatically decoupled from the rest of the protein and the solvent with a mass scaling factor s(m) =1000 and the sampling is enhanced with a scaling of the temperature using s(T) =2 or of the force using s(V) =0.667. Over 5 ns of simulation the secondary structure of the protein remains unaltered while a combined dihedral-angle conformational cluster analysis shows an increase of conformations outside the first most populate... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279201 Mon, 03 Oct 2011 22:37:25 +0100 5279201 http://www.medworm.com/index.php?rid=5279200&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21954005%26dopt%3DAbstract Influence of mg(2+) on the Guanine-Cytosine tautomeric equilibrium: simulations of the induced intermolecular proton transfer. Chemphyschem. 2011 Oct 4;12(14):2615-23 Authors: Cerón-Carrasco JP, Jacquemin D Abstract Metallic ions are essential for stabilizing the nucleic acid structure, and are also involved in the majority of RNA and DNA biological functions. However, at large concentrations metals may play an opposite role by promoting alterations in the genetic code (mutagenicity). To contribute to the understanding of this effect, theoretical tools are used to investigate the influence of the magnesium dication on the guanine-cytosine (GC) base pair structure and stability. To this end, a fully hydrated Mg(2+) cation is inserted in two models: an isolated GC base pair,... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279200 Mon, 03 Oct 2011 22:37:15 +0100 5279200 http://www.medworm.com/index.php?rid=5279199&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21954006%26dopt%3DAbstract Structure and Photoelectron Spectral Properties of I(-) ⋅nCO(2) Clusters: An ab Initio Study. Chemphyschem. 2011 Oct 4;12(14):2641-5 Authors: Pathak AK Abstract Structures and photoelectron spectral properties of I(-) ⋅nCO(2) (n=1-7) clusters are presented at the level of second-order Møller-Plesset perturbation theory with relativistic corrections. Triple split-valence 6-311++G(d,p) basis set functions are employed herein. It is observed that the CO(2) molecules approach the I(-) anion from one side in all the clusters and that I(-) ⋅nCO(2) clusters prefer the surface structure. The calculated vertical detachment energy of these clusters is in excellent agreement with the reported experimentally measured values (within 4 %). Efforts are also made to extract vertic... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279199 Mon, 03 Oct 2011 22:37:05 +0100 5279199 http://www.medworm.com/index.php?rid=5279198&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21954007%26dopt%3DAbstract Authors: PMID: 21954007 [PubMed - in process] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279198 Mon, 03 Oct 2011 22:36:56 +0100 5279198 http://www.medworm.com/index.php?rid=5279153&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21956860%26dopt%3DAbstract Authors: Preiss UP, Beichel W, Erle AM, Paulechka YU, Krossing I Abstract An investigation of the melting points of 520 organic 1:1 salts is presented with the aim of developing a universal, simple, physically well-founded prediction scheme. The general reliability and reproducibility of the recorded experimental data are discussed with respect to purity, phase behavior, disorder and thermal history of a given substance. Additionally, mistakes, systematic errors, or lack of conventions can lead to considerable differences in the experimental measurements. A rough error bar for the reproducibility of the melting points of organic salts of ±5 to ±15 °C can be assigned. With this restraint, we developed two simple, semiempirical, five- and nine-parameter schemes with easy-to-calc... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279153 Thu, 29 Sep 2011 04:00:00 +0100 5279153 http://www.medworm.com/index.php?rid=5279152&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21960467%26dopt%3DAbstract Authors: Heimdal J, Kaukonen M, Srnec M, Rulíšek L, Ryde U Abstract We used two theoretical methods to estimate reduction potentials and acidity constants in Mn superoxide dismutase (MnSOD), namely combined quantum mechanical and molecular mechanics (QM/MM) thermodynamic cycle perturbation (QTCP) and the QM/MM-PBSA approach. In the latter, QM/MM energies are combined with continuum solvation energies calculated by solving the Poisson-Boltzmann equation (PB) or by the generalised Born approach (GB) and non-polar solvation energies calculated from the solvent-exposed surface area. We show that using the QTCP method, we can obtain accurate and precise estimates of the proton-coupled reduction potential for MnSOD, 0.30±0.01 V, which compares favourably with experimental estimates ... Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279152 Thu, 29 Sep 2011 04:00:00 +0100 5279152 http://www.medworm.com/index.php?rid=5279151&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21960471%26dopt%3DAbstract Authors: Bühl M, Wipff G Abstract First-principles and purely classical molecular dynamics (MD) simulations for complexes of the uranyl ion (UO(2) (2+) ) are reviewed. Validation of Car-Parrinello MD simulations for small uranyl complexes in aqueous solution is discussed. Special attention is called to the mechanism of ligand-exchange reactions at the uranyl centre and to effects of solvation and hydration on coordination and structural properties. Large-scale classical MD simulations are surveyed in the context of liquid-liquid extraction, with uranyl complexes ranging from simple hydrates to calixarenes, and nonaqueous phases from simple organic solvents and supercritical CO(2) to ionic liquids. PMID: 21960471 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279151 Thu, 29 Sep 2011 04:00:00 +0100 5279151 http://www.medworm.com/index.php?rid=5279174&cid=s_37955_59_f&fid=37955&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21956851%26dopt%3DAbstract Authors: van Helden P, Ciobîcă IM PMID: 21956851 [PubMed - as supplied by publisher] (Source: Chemphyschem) Chemphyschem journals http://www.medworm.com/rss/comments.php?id=5279174 Wed, 28 Sep 2011 04:00:00 +0100 5279174