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 'Single Molecules' source. Sat, 10 Oct 2009 19:37:11 +0100 http://www.medworm.com/index.php?rid=219747&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C336%253A%253AAID-SIMO336%253E3.0.CO%253B2-8 No Abstract (Source: Single Molecules) Single Molecules journals http://www.medworm.com/rss/comments.php?id=219747 Wed, 04 Oct 2006 15:16:06 +0100 219747 http://www.medworm.com/index.php?rid=219746&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C328%253A%253AAID-SIMO328%253E3.0.CO%253B2-4 No Abstract (Source: Single Molecules) Single Molecules journals http://www.medworm.com/rss/comments.php?id=219746 Wed, 04 Oct 2006 15:16:06 +0100 219746 http://www.medworm.com/index.php?rid=219745&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C327%253A%253AAID-SIMO327%253E3.0.CO%253B2-8 No Abstract (Source: Single Molecules) Single Molecules journals http://www.medworm.com/rss/comments.php?id=219745 Wed, 04 Oct 2006 15:16:06 +0100 219745 http://www.medworm.com/index.php?rid=219744&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C325%253A%253AAID-SIMO325%253E3.0.CO%253B2-G No Abstract (Source: Single Molecules) Single Molecules journals http://www.medworm.com/rss/comments.php?id=219744 Wed, 04 Oct 2006 15:16:06 +0100 219744 http://www.medworm.com/index.php?rid=219743&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C323%253A%253AAID-SIMO323%253E3.0.CO%253B2-O No Abstract (Source: Single Molecules) Single Molecules journals http://www.medworm.com/rss/comments.php?id=219743 Wed, 04 Oct 2006 15:16:06 +0100 219743 http://www.medworm.com/index.php?rid=219742&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C321%253A%253AAID-SIMO321%253E3.0.CO%253B2-W In this work we present a framework for the calculation of the conduction properties of a metal-molecule-metal junction which is in contact with its thermal environment. The effects of thermal relaxation and dephasing on the transmission properties of the junction were studied using a simple tight binding model for the molecular conductor. The interaction between the molecular system and the thermal environment is described on the level of the Redfield theory, which is a weak electron-phonon coupling scheme, modified for the description of steady-state situations. We show that the transmitted flux consists of two (generally non-separable) components: a flux associated with the elastic tunneling and a thermally activated flux component. The coherent (tunneling) component dominates the trans... Single Molecules journals http://www.medworm.com/rss/comments.php?id=219742 Wed, 04 Oct 2006 15:16:06 +0100 219742 http://www.medworm.com/index.php?rid=219741&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C319%253A%253AAID-SIMO319%253E3.0.CO%253B2-4 The initial event in bacterial photosynthesis is the absorption of sunlight by an array of pigment-protein complexes, the so called light-harvesting complexes (LH). The absorbed light energy is then efficiently transferred to the reaction centre (RC), where the charge separation and thus the primary conversion into chemical energy takes place. The photosynthetic purple bacterium Rhodopseudomonas (Rps.) acidophila usually contains two types of light-harvesting complexes, light-harvesting complex 1 (LH1) and light-harvesting complex 2 (LH2). When grown under low-light and/or low temperature conditions, an additional spectroscopic variant of LH2 is expressed: the light-harvesting complex 3 (LH3) [1, 2]. The high-resolution crystal structure of LH3, which is also denoted as B800-820, has recen... Single Molecules journals http://www.medworm.com/rss/comments.php?id=219741 Wed, 04 Oct 2006 15:16:06 +0100 219741 http://www.medworm.com/index.php?rid=219740&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C317%253A%253AAID-SIMO317%253E3.0.CO%253B2-C Photobleaching and photoblinking have proven to be the main bottleneck for single-molecule microscopy and spectroscopy at room temperature. Here, a quantitative ensemble study of the kinetics of photoblinking and photobleaching at room temperature of a typical fluorescent label, Rhodamine 6G, in a polar, hydrogen bonding, solid matrix of polyvinylalcohol is presented as a function of the excitation intensity and the presence of oxygen. To achieve uniform irradiation of all molecules present in the excitation focus, the sample (2.0 x 10-5 M R6G in PVA spin-coated on a quartz substrate) is covered by a pinhole array mask with holes of diameter 40 [prop]m, each addressable as an individual sample. The experiments are performed at intensities between 65 mW/cm2 and 320 W/cm2 and the measured em... Single Molecules journals http://www.medworm.com/rss/comments.php?id=219740 Wed, 04 Oct 2006 15:16:06 +0100 219740 http://www.medworm.com/index.php?rid=219739&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C315%253A%253AAID-SIMO315%253E3.0.CO%253B2-K In cells and viruses as well as non-viral gene delivery systems, DNA is complexed with different molecules to form highly condensed structures. A wide range of conditions that cause DNA to collapse into compact structures has been discovered [1]. However, in most of these cases an exact description of these structures cannot be given. Since the complex stability is largely due to electrostatic forces, it can be modulated by varying the salt concentration. Apart from the biological aspects the study of the molecular structure of polyelectrolyte complexes may be used to improve our general understanding of polyelectrolyte interactions. Theoretical models reveal the structure of complexes formed between a stiff charged cylinder and an oppositely charged flexible or semiflexible polymer [2], [... Single Molecules journals http://www.medworm.com/rss/comments.php?id=219739 Wed, 04 Oct 2006 15:16:06 +0100 219739 http://www.medworm.com/index.php?rid=219738&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C313%253A%253AAID-SIMO313%253E3.0.CO%253B2-S In conclusion, AFM not only allows imaging of structures in the submicrometer range, it may also be used to manipulate them. By applying forces to the AFM tip approximately 10 fold higher than those used for imaging we were able to dislocate plugs from NPCs (see figures). The macromolecules sticking to the AFM tip can be used as substrates for further experiments, for example RT-PCR protocols. (Source: Single Molecules) Single Molecules journals http://www.medworm.com/rss/comments.php?id=219738 Wed, 04 Oct 2006 15:16:06 +0100 219738 http://www.medworm.com/index.php?rid=219737&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C311%253A%253AAID-SIMO311%253E3.0.CO%253B2-%2523 Scanning near-field optical microscopes (SNOM) illuminate a sample in the very near-field using a nanometer sized tip. Ideally, the light source should be point-like and many efforts have been made to optimize tip efficiency (see, for example, the article of Heimel et al in this issue). Very recently, Sandoghdar et al have realized a molecular probe tip in which a terrylene molecule inserted in a paraterphenyl microcrystal is attached at the extremity of the probe tip [1]. The excited molecule behaves as a point-like light source which is raster scanned over an aluminium patterned structure. We propose here an analysis of this experiment based on the field-susceptibility formalism (also called Green's Dyadic Method) [2,3]. In particular, in strong analogy with the Scanning Tunneling Micros... Single Molecules journals http://www.medworm.com/rss/comments.php?id=219737 Wed, 04 Oct 2006 15:16:06 +0100 219737 http://www.medworm.com/index.php?rid=219736&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C301%253A%253AAID-SIMO301%253E3.0.CO%253B2-3 The concept of high resolution imaging of a sample on a metal substrate by scanning near field optical microscopy (SNOM) with the tetrahedral tip is used for imaging of domains of oriented dye molecules on a metal substrate at a resolution in the order of 10 nm. The metal substrate is important for obtaining a high resolution in the SNOM images and at the same time it is expected to provide a mechanism for an increased contrast in SNOM imaging by scanning probe enhanced elastic scattering of molecules in the gap between a metal tip and a metal surface. (Source: Single Molecules) Single Molecules journals http://www.medworm.com/rss/comments.php?id=219736 Wed, 04 Oct 2006 15:16:06 +0100 219736 http://www.medworm.com/index.php?rid=219735&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C295%253A%253AAID-SIMO295%253E3.0.CO%253B2-T Porphyrin dendrimers were synthesized to mimic naturally occurring proteins, which catalyze a number of biochemically important reactions. In addition, chiral dendrimers were prepared as model compounds for the study of nanoscopic chirality. The structures of these dendrimers cannot be characterized by x-ray, as most dendrimers do not crystallize. We succeeded to image single, physisorbed dendrimers on noble metal surfaces with STM. All examined dendrimers can easily be (re)moved with the STM tip, even at low scanning currents (low pA range). One possibility to avoid this, is to change the peripheral groups of the dendrimer, so that they chemisorb on the surface. We decided to study physisorbed macromolecules with unchanged molecular properties, and investigated how the approach by Tokuhis... Single Molecules journals http://www.medworm.com/rss/comments.php?id=219735 Wed, 04 Oct 2006 15:16:06 +0100 219735 http://www.medworm.com/index.php?rid=219734&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C285%253A%253AAID-SIMO285%253E3.0.CO%253B2-X The strong electromagnetic field enhancement, occurring at illuminated metal structures with sub-wavelength dimensions, is exploited to develop Raman spectroscopy with exceedingly high sensitivity and lateral resolution, possibly down to single molecule detection. After reviewing Surface Enhanced Raman Spectroscopy (SERS) on single crystalline surfaces and colloids we present recent results on the Tip Enhanced Raman Spectroscopy (TERS) approach, where a metal tip is used as an external enhancing unit. In this way the electromagnetic and chemical surface enhancement are physically separated: the former is confined to the tip, the latter to the metal-adsorbate system. So far, TERS has been reported only for a few molecules exhibiting large Raman cross sections, such as sulphur or dye molecul... Single Molecules journals http://www.medworm.com/rss/comments.php?id=219734 Wed, 04 Oct 2006 15:16:06 +0100 219734 http://www.medworm.com/index.php?rid=219733&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C281%253A%253AAID-SIMO281%253E3.0.CO%253B2-C First results of a new dynamic approach to calculate the field enhancement at a metal ellipsoid close to a metal surface are presented. The theoretical approach is based on the solution of Maxwells equations. The numerical calculation is influenced by the dielectric constants of both metals, the angle of incidence of the monochromatic electromagnetic wave, the distance of the ellipsoid to the metal surface and the semi axis ratio of the ellipsoid. (Source: Single Molecules) Single Molecules journals http://www.medworm.com/rss/comments.php?id=219733 Wed, 04 Oct 2006 15:16:06 +0100 219733 http://www.medworm.com/index.php?rid=219732&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C275%253A%253AAID-SIMO275%253E3.0.CO%253B2-0 The use of molecular building blocks opens a new dimension for nanotechnology. Biomolecules offer a variety of possibilities for manipulation, provide a new size dimension and are especially suitable for "bottom up" approaches. Nucleic acids are of special interest due to their ability of self-organization, the achieved combinatorial information capacity and its molecular-biological processability. Here we present an approach for a molecular component systems with DNA-based elements and products that is suitable for molecular nanotechnology. Oligonucleotides thereby serve as biological modifiers of nanoparticles and surfaces to form self-assembling monolayers, and genomic DNA acts as framework for the building blocks. A first application of DNA-nanoparticle complexes could be the use as a ... Single Molecules journals http://www.medworm.com/rss/comments.php?id=219732 Wed, 04 Oct 2006 15:16:06 +0100 219732 http://www.medworm.com/index.php?rid=219731&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C267%253A%253AAID-SIMO267%253E3.0.CO%253B2-X In the last few years the visualization and tracking of single fluorescent proteins, nanometer-sized RNP particles and viruses within the cellular interior was accomplished. This became feasible by use of photostable fluorescent dyes, extremely low probe concentrations, and wide-field fluorescence microscopic setups equipped with sensitive slow-scan or intensified CCD cameras. This paper reviews the results of the studies performed so far, discusses potential problems and gives an outlook on future applications. (Source: Single Molecules) Single Molecules journals http://www.medworm.com/rss/comments.php?id=219731 Wed, 04 Oct 2006 15:16:06 +0100 219731 http://www.medworm.com/index.php?rid=219730&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C255%253A%253AAID-SIMO255%253E3.0.CO%253B2-8 Single molecule fluorescence experiments yield a stream of photocounts, whose statistical properties contain valuable information about processes within the molecule and in its microscopic environment. The photon statistics display features specific of single quantum systems and are therefore best discussed in the frame of a quantum mechanical theory of radiation. The present summary of a lecture given in April 2002 at the Hofgeismar Spring School on single molecules presents the main concepts used in quantum theory of light, together with a few useful references, and discusses some illustrations and applications to single molecule measurements drawn from the recent literature. (Source: Single Molecules) Single Molecules journals http://www.medworm.com/rss/comments.php?id=219730 Wed, 04 Oct 2006 15:16:06 +0100 219730 http://www.medworm.com/index.php?rid=219729&cid=s_33784_75_f&fid=33784&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252F1438-5171%2528200211%25293%253A5%252F6%253C253%253A%253AAID-SIMO253%253E3.0.CO%253B2-G No Abstract (Source: Single Molecules) Single Molecules journals http://www.medworm.com/rss/comments.php?id=219729 Fri, 01 Nov 2002 07:00:00 +0100 219729