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 'Laser Chemistry' source. Wed, 18 Jan 2012 19:54:59 +0100 http://www.medworm.com/index.php?rid=5428259&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flrt%2F2011%2F726964%2F Among herpesviruses, γ-herpesviruses are supposed to have typical oncogenic activities. Two human γ-herpesviruses, Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV), are putative etiologic agents for Burkitt lymphoma, nasopharyngeal carcinoma, and some cases of gastric cancers, and Kaposi's sarcoma, multicentric Castleman's disease, and primary effusion lymphoma (PEL) especially in AIDS setting for the latter case, respectively. Since such two viruses mentioned above are highly species specific, it has been quite difficult to prove their oncogenic activities in animal models. Nevertheless, the viral oncogenesis is epidemiologically and/or in vitro experimentally evident. This time, we investigated gene expression profiles of KSHV-oriented lymphoma cell... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5428259 Sun, 20 Nov 2011 12:23:08 +0100 5428259 http://www.medworm.com/index.php?rid=5428258&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fmpe%2F2011%2F929574%2F The objective was to obtain a transient response of rotor systems under the influence of fluid-induced forces generated by annular seal flow. This method overcomes some shortcomings of the traditional FSI method by improving the data transfer process between two domains. Calculated results were in good agreement with the experimental results. The annular seal was shown to have a supportive effect on rotor systems. Furthermore, decreasing the seal clearance would enhance this supportive effect. In the transient process, vibration amplitude and critical speed largely changed when the acceleration of the rotor system increased. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5428258 Sun, 20 Nov 2011 12:23:08 +0100 5428258 http://www.medworm.com/index.php?rid=5428257&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Faaa%2F2011%2F439724%2F This paper investigates the existence and uniqueness of mild solutions to the general nonlinear stochastic impulsive differential equations. By using Schaefer's fixed theorem and stochastic analysis technique, we propose sufficient conditions on existence and uniqueness of solution for stochastic differential equations with impulses. An example is also discussed to illustrate the effectiveness of the obtained results. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5428257 Sun, 20 Nov 2011 12:23:08 +0100 5428257 http://www.medworm.com/index.php?rid=5321684&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijz%2F2011%2F323847%2F The autumn migration routes of bar-headed geese captured before the 2008 breeding season at Qinghai Lake, China, were documented using satellite tracking data. To assess how the migration strategies of bar-headed geese are influenced by environmental conditions, the relationship between migratory routes, temperatures, and vegetation coverage at stopovers sites estimated with the Normalized Difference Vegetation Index (NDVI) were analyzed. Our results showed that there were four typical migration routes in autumn with variation in timing among individuals in start and end times and in total migration and stopover duration. The observed variation may be related to habitat type and other environmental conditions along the routes. On average, these birds traveled about 1300 to 1500 km, ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5321684 Sun, 16 Oct 2011 14:48:29 +0100 5321684 http://www.medworm.com/index.php?rid=5321683&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fjm%2F2011%2F954170%2F Iron-technetium alloys are of relevance to the development of waste forms for disposition of radioactive technetium-99 obtained from spent nuclear fuel. Corrosion of candidate waste forms is a function of the local cohesive energy (Eloc) of surface atoms. A theoretical model for calculating Eloc is developed. Density functional theory was used to construct a modified embedded atom (MEAM) potential for iron-technetium. Materials properties determined for the iron-technetium system were in good agreement with the literature. To explore the relationship between local structure and corrosion, MEAM simulations were performed on representative iron-technetium alloys and intermetallics. Technetium-rich phases have lower Eloc, suggesting that these phases will be more noble than iron-rich ones. Q... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5321683 Sun, 16 Oct 2011 14:48:29 +0100 5321683 http://www.medworm.com/index.php?rid=5321682&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fjaa%2F2011%2F230613%2F When injected into specific rat brain regions, the neurotransmitter candidate L-proline produces various cardiovascular changes through ionotropic excitatory amino acid receptors. The present study used an immunohistochemical double-labeling approach to determine whether intracisternally injected L-proline in freely moving rats, which increases blood pressure, activates hypothalamic vasopressin-expressing neurons and ventral medullary tyrosine-hydroxylase- (TH-) containing neurons. Following injection of L-proline, the number of activated hypothalamic neurons that coexpressed vasopressin and c-Fos was much greater in the supraoptic nucleus (SON) than in the paraventricular nucleus (PVN) of rats with increased blood pressure. The number of activated TH-containing neurons was significantly g... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5321682 Sun, 16 Oct 2011 14:48:29 +0100 5321682 http://www.medworm.com/index.php?rid=5321681&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fjamop%2F2011%2F504764%2F We report spectroscopic studies of laser-induced plasma (LIP) produced by ns-IR-Nd:YAG laser light pulses of different energies onto four different oxides of vanadium (VO, V2O3, VO2, and V2O5) in air under atmospheric pressure. For each oxide with a different oxidation state of vanadium, both electron density and plasma temperature were calculated for different time delays and laser pulse energies. The plasma temperature was determined from Boltzmann plot method, whereas the electron number density was estimated from the Saha equation. The decay rates for plasma temperature as well as electron density were observed to follow power law and were independent of the nature of vanadium oxide. These investigations provide an insight to optimize various parameters during LIBS analysis of vanadium... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5321681 Sun, 16 Oct 2011 14:48:29 +0100 5321681 http://www.medworm.com/index.php?rid=5321680&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fcrim%2Fsurgery%2F2011%2F685460%2F Basidiobolus ranarum is a widespread saprophyte fungus with pathogenic potential. It affects mainly the subcutaneous tissues of the trunk and limbs. Relatively recently, occasional reports of gastrointestinal basidiobolomycosis appeared in the literature. Due to the rarity of the condition and the nonspecific presenting features, the correct diagnosis is usually hard to reach. In this paper, we describe the clinical course of an otherwise healthy female, who presented with a colonic mass. She received subtotal colectomy followed by oral itraconazole, with successful outcome. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5321680 Sun, 16 Oct 2011 14:48:29 +0100 5321680 http://www.medworm.com/index.php?rid=5310940&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Faaa%2F2011%2F605259%2F For p∈[0,1], the generalized Seiffert mean of two positive numbers a and b is defined by Sp(a,b)=p(a-b)/arctan[2p(a-b)/(a+b)],  0<p≤1,  a≠b;  (a+b)/2,  p=0,  a≠b;  a,  a=b. In this paper, we find the greatest value α and least value β such that the double inequality Sα(a,b)<T(a,b)<Sβ(a,b) holds for all a,b>0 with a≠b, and give new bounds for the complete elliptic integrals of the second kind. Here, T(a,b)=(2/π)∫0π/2a2cos⁡2θ+b2sin⁡2θdθ denotes the Toader mean of two positive numbers a and b. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5310940 Thu, 13 Oct 2011 13:39:53 +0100 5310940 http://www.medworm.com/index.php?rid=5310939&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fame%2F2011%2F782590%2F Tropical Cyclone (TC) track changes associated with Rossby wave energy dispersion are simulated in a shallow water primitive equation model with an initial field where a TC is located south of a subtropical high. An anticyclone east of the TC appears because of Rossby wave energy dispersion. The connection of the anticyclone with the subtropical high leads to a poleward TC track deflection. The TC eventually moves across the axis of the subtropical ridge. The formation of the track may be attributed to the nonlinear interaction between the subtropical high and the TC. This work validates the conceptual model proposed by previous observational research. The scenario of the nonlinear interaction between the TC and the subtropical high may also be modified through the influence of mesoscale v... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5310939 Thu, 13 Oct 2011 13:39:53 +0100 5310939 http://www.medworm.com/index.php?rid=5301985&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fjnm%2F2011%2F495676%2F This study compares the adsorption capacity of modified CNTs using acid and heat treatment. The CNTs were synthesized from acetone and ethanol as carbon sources, using floating catalyst chemical vapor deposition (FC-CVD) method. energy-dispersive X-ray spectroscopy (EDX) and Boehm method revealed the existence of oxygen functional group on the surface of CNTs. Heat modification increases the adsorption capacity of as-synthesized CNTs for methylene blue (MB) and phenol by approximately 76% and 50%, respectively. However, acid modification decreases the adsorption capacity. The equilibrium adsorption data fitted the Redlich-Peterson isotherm. For the adsorption kinetic study, the experimental data obeyed the pseudo-second-order model. Both modifications methods reduced the surface ar... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5301985 Mon, 10 Oct 2011 12:30:27 +0100 5301985 http://www.medworm.com/index.php?rid=5301984&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijelc%2F2011%2F193041%2F Electrochemical oxidation of mycophenolate mofetil (MMF) has been studied at a glassy carbon electrode in aqueous solution over a wide pH range. MMF was oxidized on glassy carbon electrode (GCE) by an irreversible process that was controlled mainly by diffusion. The irreversibility of the electrode process was verified by different criteria. A probable mechanism for electrochemical oxidation of MMF was proposed. Differential-pulse voltammogram of the drug showed two oxidation peaks at 0.631 V and at 0.921 V (verses SCE) in phosphate buffer of pH 6.0. This process could be used to determine MMF in the concentration range of 5.0×10−7 to 7.5×10−4 M with a limit of detection of 1.48×10−7 M. The method was successfully applie... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5301984 Mon, 10 Oct 2011 12:30:27 +0100 5301984 http://www.medworm.com/index.php?rid=5194798&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fppar%2F2011%2F372854%2F It is well documented that PPARα and PPARβ/δ share overlapping functions in regulating myocardial lipid metabolism. However, previous studies demonstrated that cardiomyocyte-restricted PPARβ/δ deficiency in mice leads to severe cardiac pathological development, whereas global PPARα knockout shows a benign cardiac phenotype. It is unknown whether a PPARα-null background would alter the pathological development in mice with cardiomyocyte-restricted PPARβ/δ deficiency. In the present study, a mouse model with long-term PPARβ/δ deficiency in PPARα-null background showed a comparably reduced cardiac expression of lipid metabolism to those of single PPAR-deficient mouse models. The PPARα-null background did not rescue ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5194798 Mon, 05 Sep 2011 12:49:14 +0100 5194798 http://www.medworm.com/index.php?rid=5194797&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Faaa%2F2011%2F276874%2F We introduce a new iterative scheme for finding a common element of the set of solutions of an equilibrium problem and the set of common fixed point of a finite family of k-strictly pseudo-contractive nonself-mappings. Strong convergence theorems are established in a real Hilbert space under some suitable conditions. Our theorems presented in this paper improve and extend the corresponding results announced by many others. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5194797 Mon, 05 Sep 2011 12:49:14 +0100 5194797 http://www.medworm.com/index.php?rid=5194796&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijap%2F2011%2F708987%2F A Jaumann absorber with its metal backing replaced with a combined low-pass and polarizer FSS is investigated with respect to its absorption and its polarization-dependent low-frequency transparency properties. This structure is applied to an idealized curved wing-front end, and its monostatic radar cross-section is determined. The FSS-Jaumann structure preserves an absorption similar to the planar Jaumann absorber in the higher frequency interval and enables a partial transparency in the TEz polarization at 1 GHz. In addition, once the structure is applied to the wing-front end, a significant reduction in two-dimensional radar cross-section for both the TMz and TEz polarization over 2–16 GHz is observed. A sensitivity analysis shows that the resistivity of the inner re... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=5194796 Mon, 05 Sep 2011 12:49:14 +0100 5194796 http://www.medworm.com/index.php?rid=4983642&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fisrn%2Fcn%2F2011%2F231649%2F The past years have seen many attempts to construct digital signature schemes based on a single hard problem, like factoring or discrete logarithm. But in the near future, those systems will no longer be secure if the solution of factoring or discrete logarithms problems is discovered. In this paper, we propose a new signature scheme based on two hard number theoretic problems, factoring and discrete logarithms. The major advantage of our scheme is that it is very unlikely that factoring and discrete logarithms can be efficiently solved simultaneously, and; therefore, the security of our scheme is longer or higher than that of any scheme based on a single hard number theoretic problem. We also show that the performance of the scheme requires only minimal operation both in signing and verif... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983642 Thu, 30 Jun 2011 13:52:31 +0100 4983642 http://www.medworm.com/index.php?rid=4983641&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijp%2F2011%2F986869%2F N-(2-hydroxyethyl)ethylenediaminium iodides (HEEDAIs) and N-(2-hydroxyethyl)piperazinium iodides (HEPIs) were synthesized, and their thermal properties were analysed. The influence of HEEDAI and HEPI on I3-/I- redox behavior in binary ionic liquid was investigated. The result revealed that HEEDAI can suppress the recombination between I3- and the injected electrons in TiO2 conduction band and be used as the alternative of 4-tert-butylpyridine in the electrolyte of dye-sensitized solar cells. The electrolyte C, 0.15 mol⋅L−1 I2, HEEDAI and MPII with mass ratio of 1 : 4, gave the short-circuit photocurrent density of 9.36 mA⋅cm−2, open-circuit photovoltage of 0.67 V, fill factor of 0.52, and the corresponding photoelectric con... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983641 Thu, 30 Jun 2011 13:52:31 +0100 4983641 http://www.medworm.com/index.php?rid=4983640&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fcriid%2F2011%2F356370%2F We report on a patient who developed pruritus and palpable purpura in both lower extremities after receiving six days of intravenous vancomycin. Skin biopsy revealed leukocytoclastic vasculitis. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983640 Thu, 30 Jun 2011 13:52:31 +0100 4983640 http://www.medworm.com/index.php?rid=4983639&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Faaa%2F2011%2F616451%2F We first establish the existence and uniqueness of a solution for a stochastic p-Laplacian-type equation with additive white noise and show that the unique solution generates a stochastic dynamical system. By using the Dirichlet forms of Laplacian and an approximation procedure, the nonlinear obstacle, arising from the additive noise is overcome when we make energy estimate. Then, we obtain a random attractor for this stochastic dynamical system. Finally, under a restrictive assumption on the monotonicity coefficient, we find that the random attractor consists of a single point, and therefore the system possesses a unique stationary solution. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983639 Thu, 30 Jun 2011 13:52:31 +0100 4983639 http://www.medworm.com/index.php?rid=4983638&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Faaa%2F2011%2F385843%2F We improve the viscosity approximation process for approximation of a fixed point of a quasi-nonexpansive mapping in a Hilbert space proposed by Maingé (2010). An example beyond the scope of the previously known result is given. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983638 Thu, 30 Jun 2011 13:52:31 +0100 4983638 http://www.medworm.com/index.php?rid=4983637&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fddns%2F2011%2F760878%2F This paper deals with the problem of delay-dependent H∞ filtering for singular time-delay systems. First, a new delay-dependent condition which guarantees that the filter error system has a prescribed H∞ performance γ is given in terms of linear matrix inequalities (LMIs). Then, the sufficient condition is obtained for the existence of the H∞ filter, and the explicit expression for the desired H∞ filter is presented by using LMIs and the cone complementarity linearization iterative algorithm. A numerical example is provided to illustrate the effectiveness of the proposed method. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983637 Thu, 30 Jun 2011 13:52:31 +0100 4983637 http://www.medworm.com/index.php?rid=4983636&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fisrn%2Falgebra%2F2011%2F268096%2F Here, we present a connection between a sequence of polynomials generated by a linear recurrence relation of order 2 and sequences of the generalized Gegenbauer-Humbert polynomials. Many new and known transfer formulas between non-Gegenbauer-Humbert polynomials and generalized Gegenbauer-Humbert polynomials are given. The applications of the relationship to the construction of identities of polynomial sequences defined by linear recurrence relations are also discussed. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983636 Thu, 30 Jun 2011 13:52:31 +0100 4983636 http://www.medworm.com/index.php?rid=4983635&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Feri%2F2011%2F412150%2F This study evaluated the effectiveness of a short scale in screening for autism spectrum disorders (ASDs) and documented the prevalence of ASD in twins born in 1988–2000 as registered in the Danish Psychiatric Central Research Registry (DPCRR). Five child behaviour checklist (CBCL) items were used in a first-phase screening of all twins born 1988–2000, recruited from the Danish Twin Registry. In Denmark, nearly all psychiatric diagnoses are reported to DPCRR, and the two registers were linked for validation purposes. Parents of >16,000 twins responded (68.4%); among the twins, 108 were registered with ASD. The optimal cut-off score of two out of ten yielded a sensitivity of 79.6% and a specificity of 81.4%. The registry linkage identified 176 twins with ASD (point preval... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983635 Thu, 30 Jun 2011 13:52:31 +0100 4983635 http://www.medworm.com/index.php?rid=4983634&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fcriid%2F2011%2F787961%2F Schistosomiasis is a communicable disease which commonly involves urinary bladder causing hematuria, or large bowel causing bloody stool. The common species encountered in this lake region surrounding Lake Victoria in Tanzania are Schistosoma haematobium and Schistosoma mansoni. Complications can lead to portal hypertension due portal fibrosis in liver, and fibrosis in lung can lead to pulmonary hypertension; this commonly seen with S. mansoni. Major complications of S. maeametobium are chronic cystitis with squamous metaplasia with subsequent development of squamous cell carcinoma. Involvement of spinal cord causing paraplegia has been observed in S. haematobium. Other unusual pathology of schistosomiasis has been described, such as involvement of the appendix, ovary, prostate, and cervix... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983634 Thu, 30 Jun 2011 13:52:31 +0100 4983634 http://www.medworm.com/index.php?rid=4983633&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fcritran%2F2011%2F387645%2F Renal transplantation increases the probability of malignant tumors by about 2–4-fold overall with a much higher rate for renal epithelial malignancy. Renal tumors in renal transplant recipients are commonly conventional clear cell or papillary renal cell carcinoma. Clear cell papillary renal cell carcinoma is a recently described unique renal epithelial neoplasm with scant eosinophilic or moderate amount of clear cytoplasm and pyknotic small nuclei oriented commonly toward the apical surfaces. No such tumor has been reported in renal transplant recipients. In this paper, we describe a clear cell papillary renal cell carcinoma involving bilateral native kidneys in a patient who had received a renal transplant 2 years earlier. Clear cell papillary renal cell carcinoma commonl... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983633 Thu, 30 Jun 2011 13:52:31 +0100 4983633 http://www.medworm.com/index.php?rid=4983632&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijap%2F2011%2F427015%2F This paper describes a broadband printed cross-dipole element with four polarization reconfigurations (BPCDE_PR). The BPCDE_PR can configure two linear and two circular polarizations in the operating band of 1.7–2.5 GHz. To implement the broadband polarization reconfigurations, switched network type broadband phase shifters are proposed and designed. The fabricated BPCDE_PR prototype with switched network including broadband phase shifters shows good electrical performances and the desired polarization reconfigurable functions in the operating band. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983632 Thu, 30 Jun 2011 13:52:31 +0100 4983632 http://www.medworm.com/index.php?rid=4983631&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fedr%2F2011%2F910159%2F In conclusion, CNTO530 has a profound effect on glucose tolerance in insulin-resistant rodents likely because of improving peripheral insulin sensitivity. This effect was observed with epoetin-α and darbepoetin-α, suggesting this is a class effect, but the effect with these compounds relative to CNTO530 was decreased in duration and magnitude. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983631 Thu, 30 Jun 2011 13:52:31 +0100 4983631 http://www.medworm.com/index.php?rid=4983630&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fecam%2F2012%2F745127%2F Conventionally, a pulse taking platform is based on a single sensor, which initiates a feasible method of quantitative pulse diagnosis. The aim of this paper is to implement a pulse taking platform with a tactile array sensor. Three-dimensional wrist pulse signals are constructed, and the length, width, ascending slope, and descending slope are defined following the surface of the wrist pulse. And the pressure waveform of the wrist pulse obtained through proposed pulse-taking platform has the same performance as the single sensor. Finally, the results of a paired samples t-test reveal that the repeatability of the proposal platform is consistent with clinical experience. On the other hand, the results of ANOVA indicate that differences exist among different pulse taking depths, and this re... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983630 Thu, 30 Jun 2011 13:52:31 +0100 4983630 http://www.medworm.com/index.php?rid=4983629&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fabi%2F2011%2F506583%2F Machine learning was applied to a challenging and biologically significant protein classification problem: the prediction of avonoid UGT acceptor regioselectivity from primary sequence. Novel indices characterizing graphical models of residues were proposed and found to be widely distributed among existing amino acid indices and to cluster residues appropriately. UGT subsequences biochemically linked to regioselectivity were modeled as sets of index sequences. Several learning techniques incorporating these UGT models were compared with classifications based on standard sequence alignment scores. These techniques included an application of time series distance functions to protein classification. Time series distances defined on the index sequences were used in nearest neighbor and suppor... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983629 Thu, 30 Jun 2011 13:52:31 +0100 4983629 http://www.medworm.com/index.php?rid=4983628&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fjr%2F2011%2F583072%2F The development of a hybrid reconfigurable machine tool has been introduced. The machine tool consists of a tripod-based parallel kinematic machine (PKM) module with three degrees of freedom (DOF) and a serial linear X-Y table with two DOF. The PKM is installed on a gantry system which is capable of reconfiguring its position and orientation. In the design of tripod-based parallel mechanism, a passive link is used to enhance the stiffness and increase the working load. To avoid the buildup of the heat of the extensive actuation, three joints are actuated via the actuators with a constant length. The geometries of the PKM have been optimized for the best and highest accuracy. In this paper, its control system and the prototyping development are focused. An open architecture is applied, the ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983628 Thu, 30 Jun 2011 13:52:31 +0100 4983628 http://www.medworm.com/index.php?rid=4983627&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fija%2F2011%2F212515%2F The objectives of this paper were to identify farmers' preferred soil fertility improving tree species in agropastoral communities of Kyeizooba subcounty Bushenyi district, and characterize their litter content and assess their effect on selected soil chemical properties. Semistructured questionnaires were administered to 333 randomly selected agropastoral farmers. Litter and soils under canopy soils were sampled from three different environments: Under canopy radius (A), canopy edge (B), open pasture land up to thrice the canopy radius (C). Results revealed Eucalyptus as the most common tree species on livestock farms, followed by Erythrina abyssinica. The highest litter content was recorded for Markhamia lutea (240 g/cm2 under its canopy) followed by Croton macrostachyus (90&#... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983627 Thu, 30 Jun 2011 13:52:31 +0100 4983627 http://www.medworm.com/index.php?rid=4983626&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fjece%2F2011%2F251215%2F In this study, we present desktop software, called PCDReader, which could be an effective and convenient solution for patch clamp data preprocessing for daily laboratory use. We designed a novel class module, called clsPulseData, to directly read the raw data along with the parameters recorded from HEKA instruments without any other program support. By a graphical user interface, raw binary data files can be converted into several kinds of ASCII text files for further analysis, with several preprocessing options. And the parameters can also be viewed, modified and exported into ASCII files by a user-friendly Explorer style window. The real-time data loading technique and optimized memory management programming makes PCDReader a fast and efficient tool. The compiled software along with the ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983626 Thu, 30 Jun 2011 13:52:31 +0100 4983626 http://www.medworm.com/index.php?rid=4983625&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fcriid%2F2011%2F893515%2F Miliary tuberculosis as a cause of puerperial fever is extremely rare. It is a serious illness with nonspecific clinical manifestations and typical chest radiographic findings may not be seen until late in the course of the disease. It is often associated with maternal immunocompromised status. Here, we report a case of miliary tuberculosis in a nonimmunocompromised mother presenting as fever of unknown origin in immediate puerperium. Prolonged workup of eight weeks led to the diagnosis of miliary tuberculosis as the cause of postpartum fever that responded well to antituberculous drugs. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983625 Thu, 30 Jun 2011 13:52:31 +0100 4983625 http://www.medworm.com/index.php?rid=4983624&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fisrn%2Fcn%2F2011%2F586574%2F We propose the use of an iterative receiver based on the Space Alternating Generalized Expectation maximization (SAGE) algorithm for crosstalk cancellation in upstream vectored VDSL. In the absence of alien crosstalk, we show that when initialized with the frequency-domain equalizer (FEQ) output, the far-end crosstalk (FEXT) can be cancelled with no more real-time complexity than the existing linear receivers. In addition, the suggested approach does not require offline computation of the channel inverse and thus reduces the receiver complexity. In the presence of alien crosstalk, there is a significant gap between the rate performance of the linear receivers as compared with the single-user bound (SUB). The proposed receiver is shown to successfully bridge this gap while requiring only a ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983624 Thu, 30 Jun 2011 13:52:31 +0100 4983624 http://www.medworm.com/index.php?rid=4983623&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fecam%2F2012%2F178081%2F In this study, we consider a reliability measure called “Krippendorff's alpha” to investigate the agreement of tongue diagnostics in TCM. Besides, since it is not easy to obtain a large data set with patients rated simultaneously by many TCM practitioners, we use the renowned “bootstrapping” to obtain a 95% confidence interval for the Krippendorff's alpha. The estimated Krippendorff's alpha for the agreement among ten physicians that discerned fifteen randomly chosen patients is 0.7343, and the 95% bootstrapping confidence interval for the true alpha coefficient is [0.6570, 0.7349]. The data was collected and analyzed at the Department of Traditional Chinese Medicine, Changhua Christian Hospital (CCH) in Taiwan. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983623 Thu, 30 Jun 2011 13:52:31 +0100 4983623 http://www.medworm.com/index.php?rid=4983622&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Faai%2F2011%2F587285%2F We present an algorithm for tuning an expert system to minimize the expected misclassification cost. The algorithm employs data reserved for training data mining models to determine the decision cutoff of the expert system, in terms of the certainty factor of a prediction, for optimal performance. We evaluate the proposed algorithm and find that tuning the expert system results in significantly lower costs. Our approach could be extended to enhance the performance of any intelligent or knowledge system that makes cost-sensitive business decisions. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983622 Thu, 30 Jun 2011 13:52:31 +0100 4983622 http://www.medworm.com/index.php?rid=4983621&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fcrirad%2F2011%2F141563%2F Massive hemoptysis is a life-threatening medical emergency. Prompt radiological diagnosis and management are essential. I present a case of an inflammatory pulmonary aneurysm (Rasmussen aneurysm) from active pulmonary tuberculosis. This is an uncommon cause for massive hemoptysis which was successfully treated by endovascular coiling. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983621 Thu, 30 Jun 2011 13:52:31 +0100 4983621 http://www.medworm.com/index.php?rid=4983620&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fisrn%2Frheumatology%2F2011%2F654027%2F The aim of this longitudinal study is to present data from 76 female patients treated with bisphosphonates (BPs) for postmenopausal osteoporosis and referred to the Unit of Oral Diagnosis and Day Surgery of the University of Milano for diagnosis and treatment. All patients received a thorough oral examination. The diagnosis of osteonecrosis of the jaw bone (ONJ) was made from radiographic and clinical findings. 9% of individuals had BRONJ at first visit. Patients with dental or periodontal abscess were significantly more likely to develop BRONJ (OR: 2.9, 95% CI 0.5–15.9). Patients with osteoporosis receiving BPs may develop BRONJ, especially in the presence of an active infectious process in the mouth. Clinicians should carefully follow up on individuals receiving bisphosphon... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983620 Thu, 30 Jun 2011 13:52:31 +0100 4983620 http://www.medworm.com/index.php?rid=4983619&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fdrp%2F2011%2F807906%2F Conclusions. MPS provided improvement of skin hydration but not skin elasticity in woman with dry skin, compared with vehicle control. And MPS improved the skin hydration for at least 10 hours after single application. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983619 Thu, 30 Jun 2011 13:52:31 +0100 4983619 http://www.medworm.com/index.php?rid=4983618&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fcriu%2F2011%2F415675%2F Carcinosarcoma of the bladder is an unusual tumour characterized by a combination of malignant epithelial and soft tissue elements. Most of the reported cases have been case reports or small series. Optimal treatment is uncertain. We herein report our experience in such a case treated with transurethral resection followed by radiotherapy with adverse final outcome. Treatment of bladder carcinosarcomas should be aggressive and multimodal but optional treatment is still unknown. Radiotherapy alone is insufficient as a treatment option of these aggressive tumors. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983618 Thu, 30 Jun 2011 13:52:31 +0100 4983618 http://www.medworm.com/index.php?rid=4983617&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fecam%2F2011%2F312320%2F This study examines the pharmacological effects of the hydroalcoholic extract of the dry rhizome using the open field, rota rod, elevated plus-maze (EPM), forced swimming (FST), strychnine- and pentobarbital-induced sleeping time, PTZ-induced seizures, and the inhibitory avoidance tests. VP did not show any protective effect against PTZ-induced convulsions. In the EPM, exhibited an anxiolytic-like effect through the effective enhancement of the entries (38.5%) and time spent (44.7%) in the open arms, when compared with control group. Time spent and the numbers of entrances into the enclosed arms were decreased, similar to those effects observed with diazepam. In the FST, acute treatment with VP, produced a dose-dependent decrease in immobility time, similarly to imipramine. VP also... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983617 Thu, 30 Jun 2011 13:52:31 +0100 4983617 http://www.medworm.com/index.php?rid=4983616&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fcrid%2F2011%2F945159%2F We report a first case of tuberculosis of oral cavity affecting the left alveolus from Nepal in a 63-year-old male who came to otorhinolaryngology outpatient department with a complaint of an ulcer in the oral cavity and pain in bilateral ear and throat. An ulcer measuring 1.8 cm in diameter with irregular friable margin and bleeding on touch was found in the left upper alveolar region of the oral cavity. Biopsy from the ulcer margin revealed histological features of necrotizing granulomatous lesion. Stain for acid fast bacilli was positive. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4983616 Thu, 30 Jun 2011 13:52:31 +0100 4983616 http://www.medworm.com/index.php?rid=4669644&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fisrn%2Fecology%2F2011%2F695492%2F The objective of this study was to describe fish species richness patterns in relation to a naturally occurring phosphorus gradient in three lowland streams. We hypothesized that phosphorus input in La Selva Biological Station streams is correlated with species richness. 354 individuals were identified at 4 sites: Surá, El Salto, Sábalo and Jaguar, using a cast net, a total of 150 throws were made, distributed in 10 samplings, at each site. An estimation of species richness along with alpha and beta diversity indices were calculated in order to describe fish community structure. Species richness was estimated to be higher at Jaguar but presents a lower phosphorus enrichment. Jaguar and Sábalo, differed the most while Salto and Surá were the most similar as indicated by ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4669644 Sun, 03 Apr 2011 14:19:49 +0100 4669644 http://www.medworm.com/index.php?rid=4337161&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2010%2F148268.html A technique to study femtosecond laser induced structural change inside glasses, the transient lens (TrL) method, is described. Because the TrL method is sensitive to the refractive index change around the photoexcited region, the time dependence of the density, pressure, and temperature changes, which accompany refractive index change, can be monitored over a broad range of timescales. In the picosecond-nanosecond time range, the pressure wave generation was observed as an oscillating TrL signal. By comparing the TrL signal with that calculated based on thermoelastic simulation, the density, pressure, and temperature changes in the photoexcited region can be estimated. In the longer time range (nanoseconds—milliseconds), the thermal diffusion process was observed. By fitting the TrL... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4337161 Thu, 13 Jan 2011 00:53:42 +0100 4337161 http://www.medworm.com/index.php?rid=4252584&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2010%2F140976.html Advanced Pulsed Laser Deposition (PLD) processes allow the growth of oxide thin film heterostructures on large area substrates up to 4-inch diameter, with flexible and controlled doping, low dislocation density, and abrupt interfaces. These PLD processes are discussed and their capabilities demonstrated using selected results of structural, electrical, and optical characterization of superconducting (YBa2Cu3O7−δ), semiconducting (ZnO-based), and ferroelectric (BaTiO3-based) and dielectric (wide-gap oxide) thin films and multilayers. Regarding the homogeneity on large area of structure and electrical properties, flexibility of doping, and state-of-the-art electronic and optical performance, the comparably simple PLD processes are now advantageous or at least fully competitiv... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4252584 Mon, 13 Dec 2010 14:11:17 +0100 4252584 http://www.medworm.com/index.php?rid=4132609&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2010%2F143684.html This study further provides a methodology for the proper design of electrocatalysts that might be considered to be developed by the pulsed laser deposition technique. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4132609 Thu, 04 Nov 2010 19:32:24 +0100 4132609 http://www.medworm.com/index.php?rid=4039925&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1994%2F032196.abs.html This paper reports on the results about the SF6 + Ba (surface) reactions as a function of the vibrational excitation of the polyatomic molecule. A thermal, vibrationally excited by a tunable CO2 laser, SF6 beam is collided with a Ba surface target under high vacuum conditions. The total negative ion yield is measured as a function of the laser wavelength. Preliminary results show a strong vibrational enhancement of the beam-surface reactions indicating important laser-assisted negative ionization effects. The results are discussed in the light of several possible reaction mechanisms. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039925 Thu, 07 Oct 2010 21:32:50 +0100 4039925 http://www.medworm.com/index.php?rid=4039924&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1990%2F032023.abs.html Pulsed, supersonic molecular beams and pulsed lasers are particularly well matched tools when combined in molecular reaction dynamics studies. Salient features of an experiment using two pulsed molecular beam sources, a pulsed ultra-violet laser for creating reactive atoms by laser ablation and a pulsed dye laser for performing laser-induced fluorescence detection of the products are described. Differences with steady-state molecular beam experiments are outlined with respect to the following points: facility of inverting the data, possibility of obtaining high signal-to-background ratios and wide ranges of collision energy. These points are illustrated with some results concerning the reactions:C(n3P)J + NO(Xπr2)→ CN(X2Σ2) + O(n3PJ),... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039924 Thu, 07 Oct 2010 21:32:50 +0100 4039924 http://www.medworm.com/index.php?rid=4039923&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1998%2F031690.abs.html The velocity distributions for the Cl(2P3/2) and Cl(2P1/2) photofragments produced by the photolysis of Cl2 at 308 nm are measured using ion imaging. The angular distributions yield anisotropy parameters of β(2P3/2)=−1.00±0.05,β(2P1/2)=−0.95±0.05, suggesting that Cl(2P3/2) and Cl(2P1/2) is essentially produced via non-adiabatic curve crossing between the lu and the 0u+ excited electronic states. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039923 Thu, 07 Oct 2010 21:32:50 +0100 4039923 http://www.medworm.com/index.php?rid=4039922&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1994%2F031408.abs.html 193 nm excimer laser irradiation of Ar/C6F6 samples during deposition onto a cryogenic surface has led to the formation and isolation of a range of products, the dominant being hexafluoro-Dewar benzene. Additional absorptions likely due to the previously unreported hexafluorobenzvalene were observed, along with extensive fragmentation and additional minor products. When either Cl2 or CCl4 was doped into the Ar/C6F6 sample as an electron trap, a number of additional product bands were noted. A few of these were destroyed by subsequent Hg arc irradiation, and at least one is tentatively assigned to the C6F6+ cation. A comparison to previous studies of the photochemistry of C6F6 is made. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039922 Thu, 07 Oct 2010 21:32:50 +0100 4039922 http://www.medworm.com/index.php?rid=4039921&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1989%2F030758.abs.html Collisions that produce a change in the total angular-momentum and quenching processes involving the triplet Z3F0 titanium excited level and diatomic molecules have been studied by laser perturbation and time-resolved spectroscopy. The thermally averaged total angular-momentum changing cross sections (z3Fi0→z3Fj0) in units of 10−16cm2 are: σ¯42=3.2±1, 1.4±0.5; σ¯43=13.3±2, 6.8±1; σ¯32 =19.0±2, 7.2±1 , respectively, for nitrogen and hydrogen colliding partners. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039921 Thu, 07 Oct 2010 21:32:50 +0100 4039921 http://www.medworm.com/index.php?rid=4039920&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1993%2F029594.abs.html Third-harmonic generation in Hg vapors, using the two-photon resonance 61S0–81S0 transition is theoretically and experimentally investigated. Calculations of the Hg contribution to the phase mismatch are presented and the effects of the absorption of the radiation, the population transfer, the saturation, and the ionization on the efficiency of the system are considered. It is shown that the population transfer is the dominant mechanism affecting the efficiency. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039920 Thu, 07 Oct 2010 21:32:50 +0100 4039920 http://www.medworm.com/index.php?rid=4039919&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1996%2F029359.abs.html By using two independent and different methods, absolute values of the reaction cross-sections have been determined for the following chemiluminescent reactions Ca(3P,1D)+Cl4C(CHBr3)→CaX*(A,​ B)(X=Cl, Br)+Cl3C(CHBr2) and Ca(1D)+H2O→CaOH*+H Both chemiluminescence and laser-induced fluorescence spectra are reported. A comparison with related types of reactions is also presented. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039919 Thu, 07 Oct 2010 21:32:50 +0100 4039919 http://www.medworm.com/index.php?rid=4039918&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1990%2F028350.abs.html The time-resolved Raman spectra of the first triplet state–in resonance with the Tn←T1 absorption at 370 nm–and of the radical cation transient–in resonance with the R+⋅∗←R+⋅ absorptions at 370 nm and in the 560-600 nm range-are reported for fluorene. The triplet state Raman spectra of dibenzofuran and dibenzothiophen are also given. The vibrational assignments, resonance Raman activity and intensity enhancement effects are studied. On this basis, the structures and electronic configurations of the triplet state and radical cation transients and the nature of the resonant Tn←T1 and R+⋅∗←R+⋅ transitions are discussed. It turns out from this investigation that the title molecules present close analogies w... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039918 Thu, 07 Oct 2010 21:32:50 +0100 4039918 http://www.medworm.com/index.php?rid=4039917&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1989%2F027095.abs.html With reference to recent laser investigations of excited state reactions of maleic acid in Letokhov’s group, relevant excited state constants were determined by means of a physico-mathematical methods package of nonlinear absorption and the excited state populations were calculated for the experimental conditions. Based on this, a change of the assignment of the found reactions to excited states is suggested in the following manner: dimerization in T1 and maleic acid formation in a higher excited triplet. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039917 Thu, 07 Oct 2010 21:32:50 +0100 4039917 http://www.medworm.com/index.php?rid=4039916&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1993%2F026032.abs.html Discussion of the recorded spectra in terms of the electronic structure of the compounds indicates lack of dynamical bias in the VUV photoionization/fragmentation of metal complexes. Excitation with VUV light results in simpler ionic fragmentation patterns than what observed with electron-impact ionization, thereby enabling accurate monitoring of the excimer-laser photodissociation of organometallics. Finally, the intensity of the VUV ionic signal appears to be adequate for molecular-beam studies. An illustrative example is provided for the study of the 248nm-induced photodesorption of Mo(CO)6 from cryogenic films. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039916 Thu, 07 Oct 2010 21:32:50 +0100 4039916 http://www.medworm.com/index.php?rid=4039915&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1996%2F025786.abs.html Multiphoton dissociation processes of vinyl chloride and bromide were studied with a broadband ArF laser at 193 nm and with a narrowband tunable laser in the region of 212 nm, in the peak and in the threshold of the absorption band, respectively, for both compounds. Photolysis at 193 nm gives rise to the corresponding hydrogen halide in the B1∑+ excited state which results in an intense UV emission. However these emissions are absent when photodissociation was performed with the narrow band dye laser around 212 nm. These results, together with a calculation of the observed spectra, give further support to a mechanism which invokes one-photon resonant absorption of vibrationally hot ground state hydrogen halide as the process which populates the excited B1∑+ state of the fragmen... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039915 Thu, 07 Oct 2010 21:32:50 +0100 4039915 http://www.medworm.com/index.php?rid=4039914&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1990%2F024768.abs.html During the past 15 years, laser photolysis has been the method of choice for probing the complex reaction kinetics of respiratory proteins. In an attempt to determine the structural parameters which govern their reactivity, synthetic heme model compounds capable of simulating particular aspects of the reactivity of the active site of hemoproteins have been successively proposed. Laser photolysis of heme compounds merely induces a reversible photodissociation of one ligand at a time. This is equivalent to performing a fast concentration jump "in situ" and provides a powerful, fast and "clean" chemical relaxation technique. To gather association and dissociation rate constants of various ligands (O2, CO, nitrogenous bases) special methods have been developed or adapted. The problem of compar... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039914 Thu, 07 Oct 2010 21:32:50 +0100 4039914 http://www.medworm.com/index.php?rid=4039913&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1989%2F023523.abs.html Relative values of the total chemiluminescence cross.section for the crossed molecular beam Ca∗+SF6→CaF(A2Π)+SF6 reaction have been measured as a function of collision energy. Both metastable calcium atom states 3P1 were produced by low voltage de-discharge while translational excitation of the SF6 beam was achieved via the seeding technique. Whereas chemiluminescence yield from the CaF(A2Π) was observed from both of the metastable atom reactions, no chemiluminescence signal was detected from the ground atom reaction even though enough translational excitation was used to produc.e that excited product. By changing the discharge conditions different metastable concentrations were produced to measure the state-to-state cross-section for both 3P and 1D reactions, ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039913 Thu, 07 Oct 2010 21:32:50 +0100 4039913 http://www.medworm.com/index.php?rid=4039912&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1993%2F021460.abs.html We present theoretical results which show the existence of isomerizing localized quantum states above potential barriers for the excited 1B2 states of SO2 and O3. These states are assigned by periodic orbits which emerge from saddle-node bifurcations, the characteristic of which is the simultaneous generation of two families of periodic orbits one stable and one unstable. Similar isomerizing states and bifurcations have been found for other molecules, and this leads to the conclusion, that the appearance of saddle-node type states may be a generic phenomenon for molecular potentials with barriers. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039912 Thu, 07 Oct 2010 21:32:50 +0100 4039912 http://www.medworm.com/index.php?rid=4039911&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1989%2F018750.abs.html The evolution since 1982, of far-UV laser photoablation of polymers is described. The experimental data can be fitted by using a dynamic model which states that the irradiated interface moves at a rate proportional to the difference between, the intensity reaching it, and the ablation threshold intensity It. The screening effect of the ablated gaseous products is taken into account. The experimental etch depth versus fluence, obtained with our new quartz crystal microbalance technique, can be fitted by adjusting two parameters of this model; the mean absorption coefficient of the products β and the so-called ablation rate constant k, which is the etch rate for I=It+1 MW/cm2. These two parameters are wavelength dependent. The model allows also the calculation of the dose of absorbed ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039911 Thu, 07 Oct 2010 21:32:50 +0100 4039911 http://www.medworm.com/index.php?rid=4039910&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1993%2F017687.abs.html The importance of molecular complexes in gas discharge lasers has long been recognised, and indeed they are the essence in excimer lasers. For other discharge lasers operating with gas mixtures, for example metal vapour lasers, the role of molecular complexes in the laser discharge has hardly been addressed. In this work the emission from a cw multi-colour hollow-cathode HeCd+ laser has been investigated spectroscopically, and emphasis was placed on the detection of molecular bands. Specifically the presence of He2∗ in the laser discharge was confirmed which is thought to play a major role in the generation of the green laser lines. Emission bands attributed to the Cd2∗ metal dimer were identified; however, this dimer does not seem to be of importance in the laser process. In... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039910 Thu, 07 Oct 2010 21:32:50 +0100 4039910 http://www.medworm.com/index.php?rid=4039909&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1996%2F017451.abs.html Laser ablation mechanism at 248 nm irradiation of polystyrene film was investigated and discussed. An ablation threshold was determined by etch depth measurement and nanosecond photographic observation. Temperature at the threshold was evaluated to be 370℃ by using an effective absorption coefficient which was confirmed by transmission measurement of the excitation pulse. The temperature was in good agreement with that of thermal degradation of the polymer, showing that 248 nm ablation of polystyrene was brought about by a photothermal process. Nanosecond photography upon the ablation could be well interpreted from the photothermal viewpoint. Moreover, dynamics of excited species revealed by nanosecond time-resolved luminescence measurements was inferred in relation to the ablation. ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039909 Thu, 07 Oct 2010 21:32:50 +0100 4039909 http://www.medworm.com/index.php?rid=4039908&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1990%2F016432.abs.html (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039908 Thu, 07 Oct 2010 21:32:50 +0100 4039908 http://www.medworm.com/index.php?rid=4039907&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1996%2F013869.abs.html Using techniques of delayed pulsed-field ionization zero-kinetic-energy (ZEKE) photoelectron spectroscopy, we have resolved spin-orbit structure in the rotational profile of the origin band in the non-resonant two-photon threshold photoionization of propyne. Both the rotational and spin-orbit characteristics of this band are well-simulated by a simple model that assumes the spin-orbit splitting of acetylene cation in combination with the rotational constants of the neutral propyne ground state. This result, combined with very little evidence for photoionizing transitions terminating on vibronically excited states, suggests that the structure of the propyne cation structure is very close to that of the neutral ground state and very little altered by Jahn-Teller distortion. (Source: Laser Ch... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039907 Thu, 07 Oct 2010 21:32:50 +0100 4039907 http://www.medworm.com/index.php?rid=4039906&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2000%2F013792.abs.html A study on the desorption of carbendazim (methyl-2-benzimidazolecarbamate, mass = 191 amu) from a glass surface (Pyrex) has been carried out using an experimental set-up based on laser desorption and laser post-ionization followed by time-of-flight mass spectrometry. After optimization of the experimental conditions a resolution of ca. 850 was achieved at the mass of the pesticide (191 amu). All measured time-of-flight mass spectra showed not only an excellent signal to noise ratio, but also the lack of significant molecular fragmentation, except for a mass of 71 amu which was attributed to the lateral chain of the carbendazim. Neutral time-of-flight yields were measured for several desorption energies. Analysis of the corresponding velocity distributions suggests a thermal mechanism d... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039906 Thu, 07 Oct 2010 21:32:50 +0100 4039906 http://www.medworm.com/index.php?rid=4039905&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1990%2F012860.abs.html Kauffman and Bentley [Laser Chem. 8, 49-59 (1988)] have reported increased laser output by changing the anion of certain pyridinium oxazole dyes from the tosylate to the mesylate salt. Likewise, zwitterion variants of these dyes are also reported to have a significantly improved laser output. We find anion changes to be modest and, with one exception, all zwitterions tested were no better or not as good as the tosylate salt with respect to lasing output. However, both the mesylate salt and the zwitterion variants have greatly improved lifetimes if there is no fluorine auxochrome in the basic dye. These authors also report observation of bifurcated lasing output curves. We see no such phenomena. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039905 Thu, 07 Oct 2010 21:32:50 +0100 4039905 http://www.medworm.com/index.php?rid=4039904&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F1997%2F010561.abs.html The simultaneous two-photon excitation energy transfer (SEET) was demonstrated for the first time using trichromophoric model compounds. Two identical donors (A–antenna) were covalently linked to an energy acceptor unit (T–target) with different energy levels preventing energy transfer of a single photon. At high intensity illumination (laser exposure) of a trichromophoric system A∼T∼A (A–fluorescein, erythrosin; T-Estilbene), sufficient to excite both of the appended donor subunits, population of the target excited state may occur via simultaneous energy transfer of two photons, one from each donor. In order to restrict reverse energy transfer from the higher energy target to the lower energy donor(s) it is necessary that the excited target unit undergoes an ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=4039904 Thu, 07 Oct 2010 21:32:50 +0100 4039904 http://www.medworm.com/index.php?rid=2954051&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2007%2F071039.abs.html Conclusion. Wounded cells irradiated in IR light showed an undesirable thermal effect that was proportional to the duration of exposure. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2954051 Tue, 03 Nov 2009 16:02:49 +0100 2954051 http://www.medworm.com/index.php?rid=2597779&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2009%2F436065.html The effect of the applied potentials, temperature, and F− ions on the localized repassivation kinetics of titanium was investigated by the photon rupture method, PRM, and electrochemical techniques in phosphate buffered saline solution. The log⁡ I versus log⁡ t plots after laser beam irradiation showed a rapid increase, then a decrease with a slope of about −1.5, which is steeper than that expected from high field oxide film formation theory, suggesting that the repassivation of titanium is a combination of electrochemical and chemical reactions. The repassivation current increases with increases in the applied potential and addition of F− ions, while solution temperature does not influence the repassivation kinetics. The effect of F&#x221... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2597779 Tue, 14 Jul 2009 12:10:53 +0100 2597779 http://www.medworm.com/index.php?rid=2579825&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2009%2F295765.abs.html Recent progress in aerosol science has resulted in more challenging demands in the design of new particle beam introduction systems. In this paper, the concept of a variable orifice aerodynamic lens system is presented and supported by the numerical simulation results. This novel particle beam inlet can serve as either a narrow band pass filter (a particle segregator) that only confines particles with a specific size or a broad band pass filter (a particle concentrator) that allows particles with a wide size range to be concentrated on the beam axis. Following a brief description of the inlet system, computational details are described. Simulation of this inlet has been carried out by the commercial computational fluid dynamics protocol FLUENT. Focusing performance and characteristic of si... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2579825 Wed, 08 Jul 2009 12:15:02 +0100 2579825 http://www.medworm.com/index.php?rid=2579824&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2009%2F474858.abs.html This paper describes the experimental realization and characterization of a versatile single particle detection apparatus. The system utilizes a novel particle beam inlet that can serve as either an on-line particle concentrator (i.e., all diameters confined in a narrow beam) or as a segregator (i.e., selected diameters confined in a narrow beam) and can be operated in a high-speed mode as well as in a low-speed mode, thus allowing different interaction times between the particles and the laser beam. An aerodynamic sizing technique has been incorporated into the system to provide rapid, real-time, and high-resolution sizing. Parameters such as transmission efficiency and size-segregation efficiency have been measured. The performance of the instrument has been demonstrated by on-line detec... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2579824 Wed, 08 Jul 2009 12:15:02 +0100 2579824 http://www.medworm.com/index.php?rid=2550150&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2009%2F295765.html Recent progress in aerosol science has resulted in more challenging demands in the design of new particle beam introduction systems. In this paper, the concept of a variable orifice aerodynamic lens system is presented and supported by the numerical simulation results. This novel particle beam inlet can serve as either a narrow band pass filter (a particle segregator) that only confines particles with a specific size or a broad band pass filter (a particle concentrator) that allows particles with a wide size range to be concentrated on the beam axis. Following a brief description of the inlet system, computational details are described. Simulation of this inlet has been carried out by the commercial computational fluid dynamics protocol FLUENT. Focusing performance and characteristic of si... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2550150 Sun, 28 Jun 2009 16:12:25 +0100 2550150 http://www.medworm.com/index.php?rid=2550149&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2009%2F474858.html This paper describes the experimental realization and characterization of a versatile single particle detection apparatus. The system utilizes a novel particle beam inlet that can serve as either an on-line particle concentrator (i.e., all diameters confined in a narrow beam) or as a segregator (i.e., selected diameters confined in a narrow beam) and can be operated in a high-speed mode as well as in a low-speed mode, thus allowing different interaction times between the particles and the laser beam. An aerodynamic sizing technique has been incorporated into the system to provide rapid, real-time, and high-resolution sizing. Parameters such as transmission efficiency and size-segregation efficiency have been measured. The performance of the instrument has been demonstrated by on-line detec... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2550149 Sun, 28 Jun 2009 16:12:25 +0100 2550149 http://www.medworm.com/index.php?rid=2504699&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2009%2F295765.html Recent progress in aerosol science has resulted in more challenging demands in the design of new particle beam introduction systems. In this paper, the concept of a variable orifice aerodynamic lens system is presented and supported by the numerical simulation results. This novel particle beam inlet can serve as either a narrow band pass filter (a particle segregator) that only confines particles with a specific size or a broad band pass filter (a particle concentrator) that allows particles with a wide size range to be concentrated on the beam axis. Following a brief description of the inlet system, computational details are described. Simulation of this inlet has been carried out by the commercial computational fluid dynamics protocol FLUENT. Focusing performance and characteristic of si... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2504699 Thu, 25 Jun 2009 08:52:59 +0100 2504699 http://www.medworm.com/index.php?rid=2468254&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F075831.abs.html Laser cleaning tests were performed on five archaeological copper alloy objects using a Q-switched Nd:YAG laser at 1064 nm. As a comparison, a section of each object was cleaned mechanically. Prior to cleaning, cross-sections were prepared to characterise the corrosion crust and help to locate the position of the original surface. Laser cleaning was not successful at removing burial deposits on two of the objects. For the other three objects, the laser removed most of the corrosion crust. This was not always satisfactory, as cleaning was sometimes accompanied by the loss of the original surface. In addition, laser-cleaned surfaces were matt compared to mechanically cleaned surfaces. In some instances, the former had a disfiguring purple hue which was attributed to the formation of particle... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468254 Wed, 10 Jun 2009 05:06:34 +0100 2468254 http://www.medworm.com/index.php?rid=2468253&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F031862.abs.html Nanosecond laser (1064 nm wavelength) cleaning of artificially soiled paper as a model sample simulating a real-world artwork was performed. During the cleaning process, the ejection of particles was monitored in situ by means of a dust monitor (8 size classes, ranging from 0.3 μm to >2 μm) and ex situ using a mini-cascade impactor (MKI, 5 stages). The cleaning result was analyzed by scanning electron microscopy (SEM) considering possible laser-induced damages to the substrate. Size distributions of emitted particles were measured depending on the processing parameters: laser fluence, F, and pulse number per spot, N. High numbers of large (>2 μm) particles were collected by the mini-cascade impactor indicating a gas dynamical liftoff process. ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468253 Wed, 10 Jun 2009 05:06:34 +0100 2468253 http://www.medworm.com/index.php?rid=2468252&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F082823.abs.html Laser-induced fluorescence (LIF) spectroscopy can provide nondestructive, qualitative analysis of protein-based binding media found in artworks. Fluorescence emissions from proteins in egg yolk and egg white are due to autofluorescent aromatic amino acids as well as other native and age-related fluorophores, but the potential of fluorescence spectroscopy for the differentiation between binding media is dependent on the choice of a suitable excitation wavelength and limited by problems in interpretation. However, a better understanding of emission spectra associated with LIF can be achieved following comparisons with total emission fluorescence spectra where a series of consecutive emission spectra are recorded over a specific range. Results using nanosecond UV laser sources for LIF of egg-... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468252 Wed, 10 Jun 2009 05:06:34 +0100 2468252 http://www.medworm.com/index.php?rid=2468251&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F057934.abs.html Remote laser-induced fluorescence of stone materials was performed with application towards cultural heritage. Fluorescence was induced in targets ∼60 m from a mobile lidar laboratory by ultraviolet laser light, either from a frequency-tripled Nd:YAG laser or from an optical parametric oscillator system. Analysis was performed on combined spectra from the different excitation wavelengths and it was noted that important additional information can be gained when using several excitation wavelengths. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468251 Wed, 10 Jun 2009 05:06:34 +0100 2468251 http://www.medworm.com/index.php?rid=2468250&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F084781.abs.html Changes of the elemental composition due to laser surface cleaning of a naturally crusted historical sandstone were investigated by means of the SEM/EDX technique. Data obtained for stone samples prior to and after laser irradiation were compared with those for noncrusted, reference ones. It has been observed that the crust removal resulting from ablative cleaning was accompanied by a decrease of the partial content of elements Al, S, K, Ca, and Mg in the range of 60–80% of their initial value recorded for the noncleaned, crust-covered stone surface. In the stone layer just under the crust coverage, a structure characterized by intergranular spaces between the SiO2 grains being the main sandstone component filled with degraded binder was observed. From the coincidence of the b... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468250 Wed, 10 Jun 2009 05:06:34 +0100 2468250 http://www.medworm.com/index.php?rid=2468249&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F090279.abs.html The application of laser cleaning to paintings is relatively recent despite its use on stone-based materials for over 30 years. The cleaning of paintings is of high importance, because it is the least reversible invasive intervention, as well as the most usual of all conservation treatments. Paintings are multilayer system of heterogeneous nature, often very sensitive and inherent difficult to clean. Being a noncontact method, laser cleaning has advantages compared to alternative techniques. Over the last decade, there have been important research studies and advances. However, they are far from sufficient to study the effects on painting materials and to establish the best parameters for each material under investigation. This paper presents a historical overview of the application of las... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468249 Wed, 10 Jun 2009 05:06:34 +0100 2468249 http://www.medworm.com/index.php?rid=2468248&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F010647.abs.html Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT) to the control of a varnish ablation process, are presented. Examination of the ablation craters made with an Er:YAG laser allows optimization of the laser emission parameters controlling fluence with respect to efficiency and safety of the ablation process. Results of measurements of ablation crater depth as a function of the number of pulses for a given fluence are presented for selected resins. This validates the applicability of SOCT to calibration of ablation conditions for the particular laser-varnish-paint layer combinations, and of its usage in planning the varnish ablation procedure. These results also imply that a review of conventional ablation thresholds is ca... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468248 Wed, 10 Jun 2009 05:06:34 +0100 2468248 http://www.medworm.com/index.php?rid=2468247&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F093658.abs.html Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT), to tracking of deformations in paintings on canvas caused by periodical humidity changes are presented. The setup is able to monitor the position of a chosen point at the surface of a painting with micrometre precision, simultaneously in three dimensions, every 100 seconds. This allows recording of deformations associated with crack formation. For the particular painting model examined, it was shown that the surface moves in-plane towards the corner, and bulges outwards (Z-direction) in response to a rise in humidity. Subsequent to the first humidification/drying cycle, translation in the Z-direction is decreased, whilst in-plane translations increase somewhat. It was al... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468247 Wed, 10 Jun 2009 05:06:34 +0100 2468247 http://www.medworm.com/index.php?rid=2468246&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F068679.abs.html A novel application of Optical Coherence Tomography utilizing infrared light of 830 nm central wavelength for non invasive examination of the structure of parchment, some covered with iron gall ink, is presented. It is shown that both the parchment and the ink applied are sufficiently transparent to light of this wavelength. In the study, Spectral OCT (SOCT) as well as Polarisation Sensitive OCT (PS-OCT) techniques were used to obtain cross-sectional images of samples of parchment based on scattering properties. The second technique was additionally employed to recover the birefringence properties and the optical axis orientations of the sample. It was shown that freshly produced parchment exhibits a degree of birefringence. However, this property declines with ageing, and samples of old p... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468246 Wed, 10 Jun 2009 05:06:34 +0100 2468246 http://www.medworm.com/index.php?rid=2468245&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F064690.abs.html In the archaeological field, some specific advantages are recognized to laser cleaning, like, for example, the absence of mechanical contacts with the sample. The cleaning procedures generally involve a multilayer structure (dust, dirty, organic deposits, and, in some cases, consolidant substances). In this work, prehistoric wood samples (found and consolidated in 1970s) have been laser irradiated (KrF excimer laser) in order to restore their original surface aspect. A certain amount of burned matter was also present. Samples came from a fragment of a prehistoric basketry found in the lake dwelling site of Fiavè-Carera, Trento, Italy (1500–1400 BC). It was observed that the laser cleaning effects are strictly dependent on the irradiation parameters (power density and number of... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468245 Wed, 10 Jun 2009 05:06:34 +0100 2468245 http://www.medworm.com/index.php?rid=2468244&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F035373.abs.html An overview of the optical coherence tomography (OCT) technique is given. Time domain, spectral and sweep source modalities are briefly described, and important physical parameters of the OCT instrument are discussed. Examples of the application of OCT to diagnosis of various art objects such as oil paintings on canvas (imaging of glaze and varnish layers), porcelain, faience, and parchment are presented. Applications to surface profilometry of painting on canvas are also discussed. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468244 Wed, 10 Jun 2009 05:06:34 +0100 2468244 http://www.medworm.com/index.php?rid=2468243&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F085324.abs.html This paper is focused on the systematic investigation of the layer-by-layer removal of corrosion products on artificially corroded metal coupons aiming to introduce a methodology for the optimum laser cleaning approach of historical metal objects. Thus, it is very important to determine the chemical composition of the studied surfaces before and after irradiation. A series of laser cleaning studies has been performed on test coupons (reference and artificially corroded). Wavelength and pulse duration effects are investigated. Initial studies were focused on the use of infrared (1064 nm) and ultraviolet (355 nm and 248 nm) radiations of nanosecond (ns) pulse duration. Damage and removal threshold values were determined for the substrates and the corrosion layers, respectively. The irradia... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468243 Wed, 10 Jun 2009 05:06:34 +0100 2468243 http://www.medworm.com/index.php?rid=2468242&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F074791.abs.html (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468242 Wed, 10 Jun 2009 05:06:34 +0100 2468242 http://www.medworm.com/index.php?rid=2468241&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F081750.abs.html The present work is a comparative study on the laser cleaning of stonework using Nd:YAG lasers at different pulse durations. The ablation rate, the degree of cleaning, and the appearance of the treated surface were studied irradiating a simulated sample and a real stone artefact using three different Nd:YAG laser systems with pulse duration of 90 microseconds, 15 nanoseconds, and 150 picoseconds. To our knowledge, the picosecond laser is here used for the first time in stone conservation. Differences in efficiency and in cleaning result are shown and discussed. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468241 Wed, 10 Jun 2009 05:06:34 +0100 2468241 http://www.medworm.com/index.php?rid=2468240&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2006%2F039046.abs.html The feasibility of laser cleaning for the removal of a variety of surface deposits from fragments of real wall paintings from the monumental cemetery of Pisa using Nd:YAG at 1064 nm at (μs), (ns), and (ps) regimes is presented. Multianalytical investigations of the samples from irradiated surfaces of fragments were carried out in order to characterize the original and added materials and to detect any laser-induced alterations; analysis included scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), laser-induced breakdown spectroscopy (LIBS), pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS), and gas chromatography-mass spectrometry (GC-MS). The presence of nitrocellulose and pure lead contaminations on the surface of the samples has been identi... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468240 Wed, 10 Jun 2009 05:06:34 +0100 2468240 http://www.medworm.com/index.php?rid=2468239&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2007%2F036024.abs.html Uranine is a diagnostic aid in ophthalmology and is used as an immunohistological stain. A photostability study on this important compound using a crossed-beam thermal lens (TL) technique was carried out. The study is based on the photodegradation (PD) behavior and rate regarding some experimental parameters such as the incident laser power, wavelength, modulation frequency, and sample concentration. The effects of such parameters on the TL signal and PD rate are discussed in details. It has been found that the PD rate is proportional to the power of the pumping laser and the concentration of the sample within the investigated range. However, the modulation frequency is found not to influence the PD rate. The photochemical quantum yield has been measured using potassium ferrioxalate actino... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468239 Wed, 10 Jun 2009 05:06:34 +0100 2468239 http://www.medworm.com/index.php?rid=2468238&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2007%2F049608.abs.html Conclusion: since the exact role of ALP is unknown, the ALP enzyme activity assay should be considered in conjunction with other cell proliferation assays such as neutral red, optical density, or more specifically bFGF expression. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468238 Wed, 10 Jun 2009 05:06:34 +0100 2468238 http://www.medworm.com/index.php?rid=2468237&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2007%2F080536.abs.html Conclusion. This study showed that the comet assay and LDH release were sensitive enough to pick up changes in laser-irradiated cells. This study also showed that cellular and genetic damage inflicted on diabetic wounded cells was dependent on dose and wavelength and that cells are able to recover and respond. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468237 Wed, 10 Jun 2009 05:06:34 +0100 2468237 http://www.medworm.com/index.php?rid=2468236&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F416251.html Since its development in 2003, the technique of Bragg grating inscription in optical fibers and waveguides with ultrafast infrared radiation and a phase mask has proven to be as simple as the standard UV-laser grating writing techniques but far more versatile. The ultrafast IR laser-based process allows for the creation of grating structures in glassy and crystalline materials that are not typically UV photosensitive. In this article, we will review the studies that have been performed at the Communications Research Centre Canada on the grating formation processes as well as applications of the ultrafast laser technique to fabricate gratings in various optical fibers and waveguides. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468236 Wed, 10 Jun 2009 05:06:34 +0100 2468236 http://www.medworm.com/index.php?rid=2468235&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F534951.html We present a short overview of recent advances in ultrashort pulse four-wave optical parametric amplification in transparent condensed bulk media with Kerr nonlinearity. Highly efficient (10% to 15% pump-to-signal energy conversion) four-wave optical parametric amplification in water and fused silica is experimentally demonstrated. The amplification process highly benefits from 1-dimensional spatial soliton propagation regime, which sets in under proper combination of cylindrical beam focusing and noncollinear phase matching geometry with millijoule pumping. Under these operating conditions, strong four-wave coupling quenches catastrophic beam break-up and filamentation, and the setup operates reasonably below the damage threshold of the nonlinear medium. The proposed methodology o... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468235 Wed, 10 Jun 2009 05:06:34 +0100 2468235 http://www.medworm.com/index.php?rid=2468234&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F656490.html The physical properties including refractive index, Abbe number, nonlinear refractive index, microhardness and thermal expansion coefficient, and spectroscopic properties of Yb3+-doped fluorophosphate laser glasses were investigated. The results show that due to the addition of fluoride, mechanical and thermal properties are promoted, emission cross-section σemi is also greatly enhanced. The largest gain coefficient σemi·τm (0.824 pm2·ms) can be obtained with the minimum pump intensity Imin (1.112 kw/cm2). This kind of Yb3+-doped fluorophosphate glass is an excellent candidate material for Yb3+-doped host for high-power generation. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468234 Wed, 10 Jun 2009 05:06:34 +0100 2468234 http://www.medworm.com/index.php?rid=2468233&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F892721.html We applied the femtosecond laser-assisted etching technique, that is, irradiation of focused femtosecond laser pulses followed by selective chemical etching, to volume removal inside sapphire. At room temperature, volume etching only slightly advanced while residue remained inside the volume. By increasing the etching temperature, complete volume etching without residue was achieved. Complete etching was, however, accompanied by undesirable phenomena of surface pits or cracks, which are expected to be excluded through further improvement of processing. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468233 Wed, 10 Jun 2009 05:06:34 +0100 2468233 http://www.medworm.com/index.php?rid=2468232&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F623872.html Microprocessing of dielectric optical coatings by UV laser ablation is demonstrated. Excimer laser ablation at deep UV wavelengths (248 nm, 193 nm) is used for the patterning of thin oxide films or layer stacks. The layer removal over extended areas as well as sub-μm-structuring is possible. The ablation of SiO2, Al2O3, HfO2, and Ta2O5 layers and layer systems has been investigated. Due to their optical, chemical, and thermal stability, these inorganic film materials are well suited for optical applications, even if UV-transparency is required. Transparent patterned films of SiO2 are produced by patterning a UV-absorbing precursor SiOx suboxide layer and oxidizing it afterwards to SiO2. In contrast to laser ablation of bulk material, in the case of thin films, the laye... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468232 Wed, 10 Jun 2009 05:06:34 +0100 2468232 http://www.medworm.com/index.php?rid=2468231&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F493059.html We present our investigations into the structuring by two-photon polymerization of a new class of photosensitive sol-gel composites exhibiting ultra-low shrinkage. We particularly focus on two composites, the first containing a zirconium alkoxide and the second a nonlinear optical chromophore. The three-dimensional photonic crystal structures fabricated using these materials demonstrate high resolution and clear bandstops in the near IR region. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468231 Wed, 10 Jun 2009 05:06:34 +0100 2468231 http://www.medworm.com/index.php?rid=2468230&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F976205.html Thermal load as well as its three-dimensional (3D) spatial distribution has been estimated inside representative materials: glass (low thermal diffusion), silicon (semimetal properties), and sapphire (a crystalline dielectric of a high thermal conductivity) for typical laser processing and direct laser writing applications. The 3D temperature distribution allows to calculate thermal stress around the focal region. This provides an assessment tool for optimization of laser microprocessing conditions for controlled laser dicing and cutting applications. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468230 Wed, 10 Jun 2009 05:06:34 +0100 2468230 http://www.medworm.com/index.php?rid=2468229&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F170632.html Laser-induced backside wet etching (LIBWE) allows the high-quality etching of transparent materials for micro- and nanopatterning. Recent own results of LIBWE with hydrocarbon and metallic absorbers (H- and M-LIBWE) are summarized and compared with selected results of other groups regarding the etching process and the etched surface. Significant results on the impact of the liquid absorber, the material and the wavelength, and the pulse length of the laser to the etching are selected for this comparison. The etching of submicron-sized periodic structures in sapphire and fused silica with interference techniques and the selection of the preferred method in dependence on the material and the processing goal discussed. The experimental results are discussed on a thermal model considering both... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468229 Wed, 10 Jun 2009 05:06:34 +0100 2468229 http://www.medworm.com/index.php?rid=2468228&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F868767.html The effect of 248 nm laser radiation, with pulse duration of 5 picoseconds, 500 femtoseconds, and 120 femtoseconds, on the optical properties and the Knoop hardness of a commercial Er/Yb-codoped phosphate glass is presented here. Refractive index changes of the order of few parts of 10-4 are correlated with optical absorption centers induced in the glass volume, using Kramers-Kroning relationship. Accordingly, substantially lower refractive index changes are measured in volume Bragg gratings inscribed in the glass, indicating that, in addition to the optical density changes, volume dilation changes of negative sign may also be associated with the 248 nm ultrafast irradiation. The Knoop hardness experimental results reveal that the glass matrix undergoes an observabl... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468228 Wed, 10 Jun 2009 05:06:34 +0100 2468228 http://www.medworm.com/index.php?rid=2468227&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F239417.html Grating writing in structured optical fibres and their properties and applications are reviewed. To date, most gratings have been written in a straightforward manner into structured fibres containing a photosensitive germanosilicate step-index core. However, gratings have also been written directly into single material, structured silica fibres and into air-clad cores using two and higher-photon processes with both UV and near IR pulsed (nanosecond-femtosecond) light. Given the intrinsic-added functionality possible within a structured optical fibre, structured fibre gratings offer further capabilities for sensors, diagnostics, lasers, and devices. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468227 Wed, 10 Jun 2009 05:06:34 +0100 2468227 http://www.medworm.com/index.php?rid=2468226&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F839315.html (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468226 Wed, 10 Jun 2009 05:06:34 +0100 2468226 http://www.medworm.com/index.php?rid=2468225&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Flc%2F2008%2F839873.html A promising avenue in the development of high-energy pulsed chemical HF/DF lasers and amplifiers is the utilization of a photon-branched chain reaction initiated in a two-phase active medium, that is, a medium containing a laser working gas and ultradispersed passivated metal particles. These particles are evaporated under the action of IR laser radiation which results in the appearance of free atoms, their diffusion into the gas, and the development of a photon-branching chain process, which involves photons as both reactants and products. The key obstacle here is the formation of a relatively large volume (in excess of 103 cm3) of the stable active medium and filling this volume homogeneously for a short time with a su... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2468225 Wed, 10 Jun 2009 05:06:34 +0100 2468225 http://www.medworm.com/index.php?rid=2117274&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F18792 This work offers an automatic identification system of Raman spectra of artistic pigments. The proposed methodology is based on a fuzzy logic system, and uses principal component analysis to reduce redundancies in data and the correlation operator as an index of similarity between two Raman spectra. Moreover, as sometimes pigments are used in mixtures by artist, the designed system is able to recognize binary mixtures of pigments on the basis of their Raman fingerprints. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117274 Wed, 21 Jan 2009 10:11:23 +0100 2117274 http://www.medworm.com/index.php?rid=2117273&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F75831 Laser cleaning tests were performed on five archaeological copper alloy objects using a Q-switched Nd:YAG laser at 1064 nm. As a comparison, a section of each object was cleaned mechanically. Prior to cleaning, cross-sections were prepared to characterise the corrosion crust and help to locate the position of the original surface. Laser cleaning was not successful at removing burial deposits on two of the objects. For the other three objects, the laser removed most of the corrosion crust. This was not always satisfactory, as cleaning was sometimes accompanied by the loss of the original surface. In addition, laser-cleaned surfaces were matt compared to mechanically cleaned surfaces. In some instances, the former had a disfiguring purple hue which was attributed to the formation of particle... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117273 Wed, 21 Jan 2009 10:11:23 +0100 2117273 http://www.medworm.com/index.php?rid=2117272&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F31862 Nanosecond laser (1064 nm wavelength) cleaning of artificially soiled paper as a model sample simulating a real-world artwork was performed. During the cleaning process, the ejection of particles was monitored in situ by means of a dust monitor (8 size classes, ranging from 0.3 μm to >2 μm) and ex situ using a mini-cascade impactor (MKI, 5 stages). The cleaning result was analyzed by scanning electron microscopy (SEM) considering possible laser-induced damages to the substrate. Size distributions of emitted particles were measured depending on the processing parameters: laser fluence, F, and pulse number per spot, N. High numbers of large (>2 μm) particles were collected by the mini-cascade impactor indicating a gas dynamical liftoff process. ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117272 Wed, 21 Jan 2009 10:11:23 +0100 2117272 http://www.medworm.com/index.php?rid=2117271&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F82823 Laser-induced fluorescence (LIF) spectroscopy can provide nondestructive, qualitative analysis of protein-based binding media found in artworks. Fluorescence emissions from proteins in egg yolk and egg white are due to autofluorescent aromatic amino acids as well as other native and age-related fluorophores, but the potential of fluorescence spectroscopy for the differentiation between binding media is dependent on the choice of a suitable excitation wavelength and limited by problems in interpretation. However, a better understanding of emission spectra associated with LIF can be achieved following comparisons with total emission fluorescence spectra where a series of consecutive emission spectra are recorded over a specific range. Results using nanosecond UV laser sources for LIF of egg-... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117271 Wed, 21 Jan 2009 10:11:23 +0100 2117271 http://www.medworm.com/index.php?rid=2117270&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F84781 Changes of the elemental composition due to laser surface cleaning of a naturally crusted historical sandstone were investigated by means of the SEM/EDX technique. Data obtained for stone samples prior to and after laser irradiation were compared with those for noncrusted, reference ones. It has been observed that the crust removal resulting from ablative cleaning was accompanied by a decrease of the partial content of elements Al, S, K, Ca, and Mg in the range of 60–80% of their initial value recorded for the noncleaned, crust-covered stone surface. In the stone layer just under the crust coverage, a structure characterized by intergranular spaces between the SiO2 grains being the main sandstone component filled with degraded binder was observed. From the coincidence of the b... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117270 Wed, 21 Jan 2009 10:11:23 +0100 2117270 http://www.medworm.com/index.php?rid=2117269&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F57934 Remote laser-induced fluorescence of stone materials was performed with application towards cultural heritage. Fluorescence was induced in targets ∼60 m from a mobile lidar laboratory by ultraviolet laser light, either from a frequency-tripled Nd:YAG laser or from an optical parametric oscillator system. Analysis was performed on combined spectra from the different excitation wavelengths and it was noted that important additional information can be gained when using several excitation wavelengths. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117269 Wed, 21 Jan 2009 10:11:23 +0100 2117269 http://www.medworm.com/index.php?rid=2117268&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F90279 The application of laser cleaning to paintings is relatively recent despite its use on stone-based materials for over 30 years. The cleaning of paintings is of high importance, because it is the least reversible invasive intervention, as well as the most usual of all conservation treatments. Paintings are multilayer system of heterogeneous nature, often very sensitive and inherent difficult to clean. Being a noncontact method, laser cleaning has advantages compared to alternative techniques. Over the last decade, there have been important research studies and advances. However, they are far from sufficient to study the effects on painting materials and to establish the best parameters for each material under investigation. This paper presents a historical overview of the application of las... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117268 Wed, 21 Jan 2009 10:11:23 +0100 2117268 http://www.medworm.com/index.php?rid=2117267&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F10647 Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT) to the control of a varnish ablation process, are presented. Examination of the ablation craters made with an Er:YAG laser allows optimization of the laser emission parameters controlling fluence with respect to efficiency and safety of the ablation process. Results of measurements of ablation crater depth as a function of the number of pulses for a given fluence are presented for selected resins. This validates the applicability of SOCT to calibration of ablation conditions for the particular laser-varnish-paint layer combinations, and of its usage in planning the varnish ablation procedure. These results also imply that a review of conventional ablation thresholds is ca... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117267 Wed, 21 Jan 2009 10:11:23 +0100 2117267 http://www.medworm.com/index.php?rid=2117266&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F93658 Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT), to tracking of deformations in paintings on canvas caused by periodical humidity changes are presented. The setup is able to monitor the position of a chosen point at the surface of a painting with micrometre precision, simultaneously in three dimensions, every 100 seconds. This allows recording of deformations associated with crack formation. For the particular painting model examined, it was shown that the surface moves in-plane towards the corner, and bulges outwards (Z-direction) in response to a rise in humidity. Subsequent to the first humidification/drying cycle, translation in the Z-direction is decreased, whilst in-plane translations increase somewhat. It was al... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117266 Wed, 21 Jan 2009 10:11:23 +0100 2117266 http://www.medworm.com/index.php?rid=2117265&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F68679 A novel application of Optical Coherence Tomography utilizing infrared light of 830 nm central wavelength for non invasive examination of the structure of parchment, some covered with iron gall ink, is presented. It is shown that both the parchment and the ink applied are sufficiently transparent to light of this wavelength. In the study, Spectral OCT (SOCT) as well as Polarisation Sensitive OCT (PS-OCT) techniques were used to obtain cross-sectional images of samples of parchment based on scattering properties. The second technique was additionally employed to recover the birefringence properties and the optical axis orientations of the sample. It was shown that freshly produced parchment exhibits a degree of birefringence. However, this property declines with ageing, and samples of old p... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117265 Wed, 21 Jan 2009 10:11:23 +0100 2117265 http://www.medworm.com/index.php?rid=2117264&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F64690 In the archaeological field, some specific advantages are recognized to laser cleaning, like, for example, the absence of mechanical contacts with the sample. The cleaning procedures generally involve a multilayer structure (dust, dirty, organic deposits, and, in some cases, consolidant substances). In this work, prehistoric wood samples (found and consolidated in 1970s) have been laser irradiated (KrF excimer laser) in order to restore their original surface aspect. A certain amount of burned matter was also present. Samples came from a fragment of a prehistoric basketry found in the lake dwelling site of Fiavè-Carera, Trento, Italy (1500–1400 BC). It was observed that the laser cleaning effects are strictly dependent on the irradiation parameters (power density and number of... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117264 Wed, 21 Jan 2009 10:11:23 +0100 2117264 http://www.medworm.com/index.php?rid=2117263&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F35373 An overview of the optical coherence tomography (OCT) technique is given. Time domain, spectral and sweep source modalities are briefly described, and important physical parameters of the OCT instrument are discussed. Examples of the application of OCT to diagnosis of various art objects such as oil paintings on canvas (imaging of glaze and varnish layers), porcelain, faience, and parchment are presented. Applications to surface profilometry of painting on canvas are also discussed. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117263 Wed, 21 Jan 2009 10:11:23 +0100 2117263 http://www.medworm.com/index.php?rid=2117262&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F85324 This paper is focused on the systematic investigation of the layer-by-layer removal of corrosion products on artificially corroded metal coupons aiming to introduce a methodology for the optimum laser cleaning approach of historical metal objects. Thus, it is very important to determine the chemical composition of the studied surfaces before and after irradiation. A series of laser cleaning studies has been performed on test coupons (reference and artificially corroded). Wavelength and pulse duration effects are investigated. Initial studies were focused on the use of infrared (1064 nm) and ultraviolet (355 nm and 248 nm) radiations of nanosecond (ns) pulse duration. Damage and removal threshold values were determined for the substrates and the corrosion layers, respectively. The irradia... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117262 Wed, 21 Jan 2009 10:11:23 +0100 2117262 http://www.medworm.com/index.php?rid=2117261&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F74791 (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117261 Wed, 21 Jan 2009 10:11:23 +0100 2117261 http://www.medworm.com/index.php?rid=2117260&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F81750 The present work is a comparative study on the laser cleaning of stonework using Nd:YAG lasers at different pulse durations. The ablation rate, the degree of cleaning, and the appearance of the treated surface were studied irradiating a simulated sample and a real stone artefact using three different Nd:YAG laser systems with pulse duration of 90 microseconds, 15 nanoseconds, and 150 picoseconds. To our knowledge, the picosecond laser is here used for the first time in stone conservation. Differences in efficiency and in cleaning result are shown and discussed. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117260 Wed, 21 Jan 2009 10:11:23 +0100 2117260 http://www.medworm.com/index.php?rid=2117259&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2006%2F39046 The feasibility of laser cleaning for the removal of a variety of surface deposits from fragments of real wall paintings from the monumental cemetery of Pisa using Nd:YAG at 1064 nm at (μs), (ns), and (ps) regimes is presented. Multianalytical investigations of the samples from irradiated surfaces of fragments were carried out in order to characterize the original and added materials and to detect any laser-induced alterations; analysis included scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), laser-induced breakdown spectroscopy (LIBS), pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS), and gas chromatography-mass spectrometry (GC-MS). The presence of nitrocellulose and pure lead contaminations on the surface of the samples has been identi... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117259 Wed, 21 Jan 2009 10:11:23 +0100 2117259 http://www.medworm.com/index.php?rid=2117258&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F36024 Uranine is a diagnostic aid in ophthalmology and is used as an immunohistological stain. A photostability study on this important compound using a crossed-beam thermal lens (TL) technique was carried out. The study is based on the photodegradation (PD) behavior and rate regarding some experimental parameters such as the incident laser power, wavelength, modulation frequency, and sample concentration. The effects of such parameters on the TL signal and PD rate are discussed in details. It has been found that the PD rate is proportional to the power of the pumping laser and the concentration of the sample within the investigated range. However, the modulation frequency is found not to influence the PD rate. The photochemical quantum yield has been measured using potassium ferrioxalate actino... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117258 Wed, 21 Jan 2009 10:11:23 +0100 2117258 http://www.medworm.com/index.php?rid=2117257&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F49608 Conclusion: since the exact role of ALP is unknown, the ALP enzyme activity assay should be considered in conjunction with other cell proliferation assays such as neutral red, optical density, or more specifically bFGF expression. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2117257 Wed, 21 Jan 2009 10:11:23 +0100 2117257 http://www.medworm.com/index.php?rid=2076784&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F839315 (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=2076784 Sat, 03 Jan 2009 20:10:05 +0100 2076784 http://www.medworm.com/index.php?rid=1999699&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F239417 Grating writing in structured optical fibres and their properties and applications are reviewed. To date, most gratings have been written in a straightforward manner into structured fibres containing a photosensitive germanosilicate step-index core. However, gratings have also been written directly into single material, structured silica fibres and into air-clad cores using two and higher-photon processes with both UV and near IR pulsed (nanosecond-femtosecond) light. Given the intrinsic-added functionality possible within a structured optical fibre, structured fibre gratings offer further capabilities for sensors, diagnostics, lasers, and devices. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1999699 Mon, 01 Dec 2008 15:34:42 +0100 1999699 http://www.medworm.com/index.php?rid=1985750&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F868767 The effect of 248 nm laser radiation, with pulse duration of 5 picoseconds, 500 femtoseconds, and 120 femtoseconds, on the optical properties and the Knoop hardness of a commercial Er/Yb-codoped phosphate glass is presented here. Refractive index changes of the order of few parts of 10-4 are correlated with optical absorption centers induced in the glass volume, using Kramers-Kroning relationship. Accordingly, substantially lower refractive index changes are measured in volume Bragg gratings inscribed in the glass, indicating that, in addition to the optical density changes, volume dilation changes of negative sign may also be associated with the 248 nm ultrafast irradiation. The Knoop hardness experimental results reveal that the glass matrix undergoes an observabl... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1985750 Tue, 25 Nov 2008 16:27:07 +0100 1985750 http://www.medworm.com/index.php?rid=1964954&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F170632 Laser-induced backside wet etching (LIBWE) allows the high-quality etching of transparent materials for micro- and nanopatterning. Recent own results of LIBWE with hydrocarbon and metallic absorbers (H- and M-LIBWE) are summarized and compared with selected results of other groups regarding the etching process and the etched surface. Significant results on the impact of the liquid absorber, the material and the wavelength, and the pulse length of the laser to the etching are selected for this comparison. The etching of submicron-sized periodic structures in sapphire and fused silica with interference techniques and the selection of the preferred method in dependence on the material and the processing goal discussed. The experimental results are discussed on a thermal model considering both... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1964954 Mon, 17 Nov 2008 14:35:53 +0100 1964954 http://www.medworm.com/index.php?rid=1945652&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F976205 Thermal load as well as its three-dimensional (3D) spatial distribution has been estimated inside representative materials: glass (low thermal diffusion), silicon (semimetal properties), and sapphire (a crystalline dielectric of a high thermal conductivity) for typical laser processing and direct laser writing applications. The 3D temperature distribution allows to calculate thermal stress around the focal region. This provides an assessment tool for optimization of laser microprocessing conditions for controlled laser dicing and cutting applications. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1945652 Sun, 09 Nov 2008 18:01:32 +0100 1945652 http://www.medworm.com/index.php?rid=1912389&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F493059 We present our investigations into the structuring by two-photon polymerization of a new class of photosensitive sol-gel composites exhibiting ultra-low shrinkage. We particularly focus on two composites, the first containing a zirconium alkoxide and the second a nonlinear optical chromophore. The three-dimensional photonic crystal structures fabricated using these materials demonstrate high resolution and clear bandstops in the near IR region. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1912389 Tue, 28 Oct 2008 18:09:34 +0100 1912389 http://www.medworm.com/index.php?rid=1881337&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F623872 Microprocessing of dielectric optical coatings by UV laser ablation is demonstrated. Excimer laser ablation at deep UV wavelengths (248 nm, 193 nm) is used for the patterning of thin oxide films or layer stacks. The layer removal over extended areas as well as sub-μm-structuring is possible. The ablation of SiO2, Al2O3, HfO2, and Ta2O5 layers and layer systems has been investigated. Due to their optical, chemical, and thermal stability, these inorganic film materials are well suited for optical applications, even if UV-transparency is required. Transparent patterned films of SiO2 are produced by patterning a UV-absorbing precursor SiOx suboxide layer and oxidizing it afterwards to SiO2. In contrast to laser ablation of bulk material, in the case of thin films, the laye... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1881337 Thu, 16 Oct 2008 17:49:20 +0100 1881337 http://www.medworm.com/index.php?rid=1838523&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F892721 We applied the femtosecond laser-assisted etching technique, that is, irradiation of focused femtosecond laser pulses followed by selective chemical etching, to volume removal inside sapphire. At room temperature, volume etching only slightly advanced while residue remained inside the volume. By increasing the etching temperature, complete volume etching without residue was achieved. Complete etching was, however, accompanied by undesirable phenomena of surface pits or cracks, which are expected to be excluded through further improvement of processing. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1838523 Tue, 30 Sep 2008 19:00:56 +0100 1838523 http://www.medworm.com/index.php?rid=1827156&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F656490 The physical properties including refractive index, Abbe number, nonlinear refractive index, microhardness and thermal expansion coefficient, and spectroscopic properties of Yb3+-doped fluorophosphate laser glasses were investigated. The results show that due to the addition of fluoride, mechanical and thermal properties are promoted, emission cross-section σemi is also greatly enhanced. The largest gain coefficient σemi·τm (0.824 pm2·ms) can be obtained with the minimum pump intensity Imin (1.112 kw/cm2). This kind of Yb3+-doped fluorophosphate glass is an excellent candidate material for Yb3+-doped host for high-power generation. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1827156 Thu, 25 Sep 2008 18:27:35 +0100 1827156 http://www.medworm.com/index.php?rid=1811667&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F416251 Since its development in 2003, the technique of Bragg grating inscription in optical fibers and waveguides with ultrafast infrared radiation and a phase mask has proven to be as simple as the standard UV-laser grating writing techniques but far more versatile. The ultrafast IR laser-based process allows for the creation of grating structures in glassy and crystalline materials that are not typically UV photosensitive. In this article, we will review the studies that have been performed at the Communications Research Centre Canada on the grating formation processes as well as applications of the ultrafast laser technique to fabricate gratings in various optical fibers and waveguides. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1811667 Sun, 21 Sep 2008 17:44:51 +0100 1811667 http://www.medworm.com/index.php?rid=1811666&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F534951 We present a short overview of recent advances in ultrashort pulse four-wave optical parametric amplification in transparent condensed bulk media with Kerr nonlinearity. Highly efficient (10% to 15% pump-to-signal energy conversion) four-wave optical parametric amplification in water and fused silica is experimentally demonstrated. The amplification process highly benefits from 1-dimensional spatial soliton propagation regime, which sets in under proper combination of cylindrical beam focusing and noncollinear phase matching geometry with millijoule pumping. Under these operating conditions, strong four-wave coupling quenches catastrophic beam break-up and filamentation, and the setup operates reasonably below the damage threshold of the nonlinear medium. The proposed methodology o... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1811666 Sun, 21 Sep 2008 17:44:51 +0100 1811666 http://www.medworm.com/index.php?rid=1710893&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1990%2F97197 The infrared multiple photon trans → cis isomerization of crotonitrile was studied over the pressure range 0.02 torr to 10 torr at fluences of approximately 4J/cm2 using collimated TEA CO2 laser radiation at 942 cm-1. Only minor quantifies of fragmentation products were found at these conditions. At pressures of 0.1 torr or less, the trans form was completely converted to cis form by about 5000 laser pulses. On increasing the pressure a collisional regime was entered in which photostationary states were reached with fewer pulses and having smaller conversions than at low pressure. Both the number of pulses and the conversion decreased monotonically with increasing pressure. The tactic of driving the reaction in the exothermic direction gave evidence that the reaction does not occur ... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1710893 Sun, 17 Aug 2008 17:41:16 +0100 1710893 http://www.medworm.com/index.php?rid=1710892&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1990%2F93626 An investigation is presented of the transient vibrational excitation of O3 in the collision dominated regime initiated by pulsed CO2-laser radiation. IR-UV-double resonance experiments and measurements of the absorbance for the CO2-laser lines 9P18, 20, and 22 were carried out. Mixtures of O3 (p=17 mbar) with 02 were investigated at pressures of 160 mbar ≤Pmixt≤1200 mbar and laser fluences of 0.10 J/cm2≤Fin< 2 J/cm2 . The results are interpreted by numerical simulations in terms of a comprehensive excitation/relaxation model based upon SSH-theory. Concerning the evolution of the excitation, simulated transients of the UV-absorbance compare well with the corresponding observed signals. The saturation of the absorbing O3-transitions is demons... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1710892 Sun, 17 Aug 2008 17:41:16 +0100 1710892 http://www.medworm.com/index.php?rid=1710891&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1990%2F91308 Various methods for the ablation of the atherosclerotic material that fills the coronary arteries are under investigation. Among them laser coronary angioplasty is one of the most promising. In this paper we show that the XeCl excimer laser (308 nm) offers many advantages which make it appear as a rather good tool. In vitro studies demonstrate the ability of precise control of the UV photoablation process, there is no thermal damage and the risk of perforation is reduced. A suitable laser-fiber optic delivery system has been developed and the results of the first in vivo procedures are very encouraging. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1710891 Sun, 17 Aug 2008 17:41:16 +0100 1710891 http://www.medworm.com/index.php?rid=1710890&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1990%2F89853 The TEA-CO2 laser induced reaction of trans-l,2-dichloroethylene (TDCE) was investigated at 925 cm-1. The laser radiation was focused to yield beam waist fluences of approximately 125 J cm-2. The major reaction product was cis-1, 2-dichloroethylene (CDCE), with a few per cent of chloroacetylene, and minor amounts of acetylene, dichloroacetylene, chloroethylene and an unidentified C4 compound also being formed. The reaction of pure TDCE was studied as a function of number of laser pulses and total pressure (0.02 to 5 torr). Some experiments were also done with added ethane (20%) and propane (2%). Evidence was obtained that the formation of the cis isomer occurs via two mechanisms, (1) a unimolecular isomerization, and (2) a CI atom chain reaction. The results are consistent with laser induc... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1710890 Sun, 17 Aug 2008 17:41:16 +0100 1710890 http://www.medworm.com/index.php?rid=1710889&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1990%2F86536 The dynamics of the Time-Dependent Fluorescence Shift (TDFS) of a rigid polar excited probe dissolved in alcohol solvents at different temperatures have been studied by picosecond time-resolved spectroscopy. The results are compared to previously published results on well characterized polar systems. These results show that solvation dynamics in such systems are strongly scaled by the microscopic (singleparticle) reorientation time τM of the solvent molecules and/or by the (macroscopic) longitudinal relaxation time τL of the solvent. The key point governing this scaling is the relative interaction between the solvent molecules and the probe compared to the interaction between the solvent molecules. It is also shown that specific interactions, such as hydrogen bonded-complex f... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1710889 Sun, 17 Aug 2008 17:41:16 +0100 1710889 http://www.medworm.com/index.php?rid=1710888&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1990%2F85290 The S1←S0 fluorescence excitation spectra and dispersed fluorescence spectra of jet-cooled (+)-, (-)- and (±)-1-phenylethylamine and their derivatives (amides) have been observed. The 0-0 band of the amine locates at 37,641 cm-1. The amides which were synthesized from (+)-amine or (-)-amine with (+)-tartaric acid are diastereomers. It was found that the two diastereomers give the identical spectra with the 0-0 band at 34,757 cm-1. No difference in the spectrum indicates that the excitation is localized in the phenyl group which is far from the asymmetric carbon causing diastereoism. It was also found that 1-phenylethylamine has a fast nonradiative relaxation process in the Sstate, but such a process is removed by the formation of the amide. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1710888 Sun, 17 Aug 2008 17:41:16 +0100 1710888 http://www.medworm.com/index.php?rid=1710887&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1990%2F82962 Laser induced fluorescence (LIF) has become a common detector of atoms and molecules allowing to determine their internal state distributions. In this paper we mention the advantages of both kinds of lasers, cw or pulsed. We review some aspects of the LIF process, such as saturation or polarization effects, which could alter the results if they were not taken into account. We also indicate how LIF can be used to measure relaxation times and thus rate constants of the relaxation processes: some experimental results obtained in our laboratory illustrate these points. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1710887 Sun, 17 Aug 2008 17:41:16 +0100 1710887 http://www.medworm.com/index.php?rid=1697905&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1999%2F18612 Third- and fifth-order impulsive stimulated Raman scattering experiments are performed to study low-frequency intermolecular vibrations in CS2/pentane binary mixtures. The changes of the optical Kerr effect response cannot be assigned unequivocally to a single microscopic process. In particular, the homogeneous and inhomogeneous line broadening mechanisms cannot be determined. Temporally two-dimensional Raman scattering experiments indicate that the correlation time of fluctuations of the intermolecular potential decreases upon dilution. The experimental results give evidence of strong coupling between the ultrafast coherent vibrations and the slow reorientational diffusion. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1697905 Tue, 12 Aug 2008 17:25:28 +0100 1697905 http://www.medworm.com/index.php?rid=1697904&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1999%2F17539 The laser photolysis (248 nm, 20 ns) of biphenyl (BP, S0) occluded in the void space of faujasitic zeolites (NanFAU) , Nan(SiO2)192−n(AlO2)n with n=0, 56, 85 has been studied by time-resolved resonance Raman spectroscopy combined with time-resolved diffuse reflectance UV-visible absorption spectroscopy in the ns–μs time scale. The excitation (370 nm, 8 ns) of the RR scattering in the wavelength region of the UV electronic absorption of the transient species provides clear evidence of the radical cation (BP+) as major species for zeolites NanFAU (n=56, 85). The amount of triplet state (BP, T1) depends on the aluminum content and in a less extent on the fluence of the pump laser at the sample. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1697904 Tue, 12 Aug 2008 17:25:28 +0100 1697904 http://www.medworm.com/index.php?rid=1697903&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1999%2F16293 The interaction between photosynthetic cofactors and the surrounding bath or protein environment is addressed via experimental measurements of the optical coherence responses from bacteriochlorophylla (Bchla) chromophores within the photosynthetic reaction center (RC) of Rhodobacter sphaeroides and solutions of Bchla monomers in THF and pyridine. The results indicate that both the spectrum of fluctuations and chromophore bath coupling strengths vary between solutions and protein. In particular, the protein environment yields faster dephasing, faster spectral diffusion, and significantly more inhomogeneity than solutions. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1697903 Tue, 12 Aug 2008 17:25:28 +0100 1697903 http://www.medworm.com/index.php?rid=1697902&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1999%2F13965 By means of infrared pump-probe technique, spectroscopic feature of vibrationally excited water molecule (D2O) on mordenite zeolite (OD) has been investigated. Populational lifetime of the OD stretching band (ν3:2730cm-1) was determined to be 43±5 ps at 123 K by the time evolution of hot band. The transient bleachings and absorptions appeared when the D2O molecule was promoted to the vibrationally excited level of the OD stretching modes. Especially, the transient absorption at 2680 cm-1 has rapid decay time (≈15 ps) and it was assigned as the overtone between ν3 mode and vibrationally excited ν1 mode (2620 cm-1). (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1697902 Tue, 12 Aug 2008 17:25:28 +0100 1697902 http://www.medworm.com/index.php?rid=1697901&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1999%2F12721 The S0, T1 and S1 Raman spectra of bacteriochlorophyll a, bacteriopheophytin a and chlorophyll a were recorded for the species of natural abundance isotopic composition and those of totally substituted with 15N, 13C and 2H isotopes. Based on empirical assignments of the Raman lines, changes in the bond orders in the macrocycle upon triplet and singlet excitation are discussed. (Source: Laser Chemistry) Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1697901 Tue, 12 Aug 2008 17:25:28 +0100 1697901 http://www.medworm.com/index.php?rid=1697900&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1999%2F10475 Vibrational relaxation dynamics of trans-stilbene in the S1 state immediately after photoexcitation is studied by picosecond time-resolved anti-Stokes Raman spectroscopy with several pump and probe wavelengths. Pump-wavelength dependence of the anti- Stokes spectrum indicates that, when pump photons with high excess energy (≈5200cm-1) are used, the anti-Stokes Raman bands at 0 ps delay time arise from vibrationally excited transients with excess vibrational energy not thermally distributed in the molecule. Probe-wavelength dependence suggests that the vibrationally excited transients at 0 ps are mostly on the lowest excited vibrational levels, as far as the olefinic C═C stretching and the C–Ph stretching modes are concerned. The vibrational relaxation process of S1trans-s... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1697900 Tue, 12 Aug 2008 17:25:28 +0100 1697900 http://www.medworm.com/index.php?rid=1697899&cid=s_37726_72_f&fid=37726&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F1999%2F90875 It has been found that the irradiation with highly intense circularly polarized light (CPL) from an XeF (351 nm) laser can induce the enantiodifferentiation of racemic methionine with reasonable enantiocontrol by switching the sense of the CPL. Also, a similar result was obtained for threonine and it was newly revealed that the enantioenrichment is largely affected by the chemical structure, especially the functional groups, of α-amino acids, to cause photodecomposition such as decarboxylation and deamination. Furthermore, it was shown for the first time that the irradiation of a proline (Pro)-valine (Val) mixture with the CPL induces their enantioselective decomposition simultaneously, suggesting the occurrence of intermolecular interaction between Pro and Val. (Source: Laser Chemist... Laser Chemistry journals http://www.medworm.com/rss/comments.php?id=1697899 Tue, 12 Aug 2008 17:25:28 +0100 1697899