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Visible Light Irradiation (visible + light_irradiation)
Selected AbstractsVisible Light Irradiation of Ethidium Bromide,stained Interphase Nuclei Causes DNA,Protein Linking and Structural Stabilization of Nucleoprotein Complexes,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2003Andrey N. Prusov ABSTRACT Fixation of DNA and proteins in the isolated rat hepatocyte nuclei stained with ethidium bromide and irradiated with visible light was analyzed in this study. It was shown that irradiation results in the following modifications of higher-level nucleoprotein complexes of interphase chromatin: (1) the complexes acquire resistance to decondensing treatments, which may be indicative of the formation of links between proteins or proteins and DNA in the chromatin; (2) the linking rate for both DNA and proteins is dose dependent; (3) the irradiation induces intermolecular link formation between DNA molecules, which brings about an increase in the average molecular weight of DNA fragments; (4) some modifications (dimerization, etc.) of histones and nonhistone proteins occur; and (5) histone proteins are not effectively cross-linked to DNA. The structural stabilization of interphase chromatin is possibly mediated by free radical,based mechanisms, whereas disulfide bonds seem to play no significant role in the cross-linking. [source] ChemInform Abstract: Tandem Oxidation/Rearrangement of ,-Ketoesters to Tartronic Esters with Molecular Oxygen Catalyzed by Calcium Iodide under Visible Light Irradiation with Fluorescent Lamp.CHEMINFORM, Issue 36 2010Naohiko Kanai Abstract The reaction tolerates aliphatic, aromatic and heteroaromatic ketoesters and can be easily scaled up. [source] ChemInform Abstract: The Synthesis of Bismuth Vanadate Powders and Their Photocatalytic Properties under Visible Light Irradiation.CHEMINFORM, Issue 26 2010Yue Shen Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Structural, Photophysical and Photocatalytic Properties of New Bi2SbVO7 under Visible Light Irradiation.CHEMINFORM, Issue 42 2009Jingfei Luan Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A Dawson-Type Dirhenium(V)-Oxido-Bridged Polyoxotungstate: X-Ray Crystal Structure and Hydrogen Evolution from Water Vapor under Visible Light Irradiation.CHEMINFORM, Issue 43 2008Chika Nozaki Kato Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Aerobic Oxidation under Visible Light Irradiation of a Fluorescent Lamp with a Combination of Carbon Tetrabromide and Triphenyl Phosphine.CHEMINFORM, Issue 15 2008Taichi Sugai Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Ruthenium(II)-Complexed Rotaxane Whose Ring Incorporates a 6,6,-Diphenyl-2,2,-bipyridine: Synthesis and Light-Driven MotionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2005Jean-Paul Collin Abstract By incorporating a 6,6'-diphenyl-2,2'-bipyridine (dpbipy) fragment in a ring, endo coordination of a ruthenium(II) center is performed selectively and almost quantitatively. The threaded system, containing a helical fragment, could be fully characterized. When the terminal functions of the rod-shaped helical complex threaded through the macrocycle are phenol groups, the complete rotaxane is prepared by the classical Williamson stoppering reaction in moderate yield. Light-induced motions of the unstoppered system (pseudorotaxane) and the real rotaxane have been studied. Under visible light irradiation, quantitative decoordination of the dpbipy-containing ring is observed, leading to the separate fragments (ring and helical thread) or to a new rotaxane (uncoordinated ring threaded by the dumbbell). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Photoregulation of DNA transcription by using photoresponsive T7 promoters and clarification of its mechanismFEBS JOURNAL, Issue 6 2010Xingguo Liang With the use of photoresponsive T7 promoters tethering two 2,-methylazobenzenes or 2,,6,-dimethylazobenzenes, highly efficient photoregulation of DNA transcription was obtained. After UV-A light irradiation (320,400 nm), the rate of transcription with T7 RNA polymerase and a photoresponsive promoter involving two 2,,6,-dimethylazobenzenes was 10-fold faster than that after visible light irradiation (400,600 nm). By attaching a nonmodified azobenzene and 2,,6,-dimethylazobenzene at the two positions, respectively, and by utilizing the different cis,trans thermal stability between cis -nonmodified azobenzene and cis- 2,,6,-dimethylazobenzene, four species of T7 promoter (cis,cis, trans,cis, cis,trans, and trans,trans) were obtained. The four species showed transcriptional activity in the order of cis,cis > cis,trans > trans,cis > trans,trans. Kinetic analysis revealed that the Km for the cis,cis promoter (both of the introduced azobenzene derivatives were in the cis form) and T7 RNA polymerase was 68 times lower than that for the trans,trans form, indicating that high photoregulatory efficiency was mainly due to a remarkable difference in affinity for RNA polymerase. The present approach is promising for the creation of biological tools for artificially controlling gene expression, and as a photocontrolled system for supplying RNA fuel for RNA-powered molecular nanomachines. [source] Light-Triggered Self-Assembly of a Spiropyran-Functionalized Dendron into Nano-/Micrometer-Sized Particles and Photoresponsive Organogel with Switchable FluorescenceADVANCED FUNCTIONAL MATERIALS, Issue 1 2010Qun Chen Abstract The synthesis, self-assembly, and spectroscopic investigations of spiropyran (SP)-functionalized dendron 1 are reported. Under UV light irradiation, assembly of 1 into nano-/microparticles occurs due to the transformation of the closed form of SP into the open merocyanine (MC) form. The formation of these nano-/microparticles is confirmed by transmission electron microscopy (TEM) and dynamic light scattering (DLS) experiments in addition to the confocal laser scanning microscopy (CLSM) measurements. These nano-/microparticles exhibit relatively strong red emission. It is interesting to note that the direct cooling of the toluene/benzene solution of 1 to 0,°C leads to gel formation. Multivalent ,,, interactions due to the dendron in 1 may be the driving-force for the gelation. The UV light irradiation cannot destroy the gel phase, and in fact, the gel,gel transition is successfully realized. The purple-blue gel exhibits relatively strong red fluorescence; moreover, the fluorescence can be reversibly switched by alternating UV and visible light irradiation. The results clearly indicate that the MC form after aggregation becomes more stable and fluorescent. [source] Water-soluble triply-responsive homopolymers of N,N -dimethylaminoethyl methacrylate with a terminal azobenzene moietyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2010Xinde Tang Abstract Novel water-soluble triply-responsive homopolymers of N,N -dimethylaminoethyl methacrylate (DMAEMA) containing an azobenzene moiety as the terminal group were synthesized by atom transfer radical polymerization (ATRP) technique. The ATRP process of DMAEMA was initiated by an azobenzene derivative substituted with a 2-bromoisobutyryl group (Azo-Br) in the presence of CuCl/Me6TREN in 1,4-dioxane as a catalyst system. The molecular weights and their polydispersities of the resulting homopolymers (Azo-PDMAEMA) were characterized by gel permeation chromatography (GPC). The homopolymers are soluble in aqueous solution and exhibit a lower critical solution temperature (LCST) that alternated reversibly in response to Ph and photoisomerization of the terminal azobenzene moiety. It was found that the LCST increased as pH decreased in the range of testing. Under UV light irradiation, the trans -to- cis photoisomerization of the azobenzene moiety resulted in a higher LCST, whereas it recovered under visible light irradiation. This kind of polymers should be particularly interesting for a variety of potential applications in some promising areas, such as drug controlled-releasing carriers and intelligent materials because of the multistimuli responsive property. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2564,2570, 2010 [source] Synthesis, characterization, and nucleotidic chain cleavage ability of uncharged water soluble poly(ethylene glycol)-fullerene derivatives with an amphiphilic characterJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2008Daniele Vitalini Abstract Water-soluble fullerenes containing two poly(ethylene glycol) branches [Full-(PEG)2] were prepared starting from commercial poly(ethylene glycol)-monomethyl ethers and C60 [Full-(PEG)2]s chemical characterization was made by FT-IR, NMR, and MALDI-TOF mass spectrometric analyses. Their thermal stability was determined by TGA experiments. The capability of C60 -derivatives to induce oligonucleotide cleavage under visible light irradiation was also ascertained. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2154,2153, 2008 [source] Application of ion beam techniques for preparation of metal ion-implanted TiO2 thin film photocatalyst available under visible light irradiation: metal ion-implantation and ionized cluster beam methodJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001Hiromi Yamashita Transparent TiO2 thin film photocatalysts have been prepared on silica glass plate by an ionized cluster beam (ICB) method. In order to improve the electronic properties of these photocatalysts, transition metal ions V+, Cr+, Mn+, Fe+) were implanted into the TiO2 thin films at high energy acceleration using an advanced metal ion-implantation technique. The combination of these ion beam techniques can allow us to prepare the TiO2 thin film photocatalysts which can work effectively under visible light (, > 450 nm) and/or solar light irradiation. The investigation using XAFS and ab initio molecular calculation suggests that the substitution of octahedrally coordinated Ti ions in TiO2 lattice with implanted metal ions is important to modify TiO2 to be able to adsorb visible light and operate under visible light irradiation. [source] Vitamin B2 -sensitized Photo-oxidation of DopaminePHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2008Walter A. Massad Kinetics and mechanism of the photo-oxidation of the natural catecholamine-type neurotransmitter dopamine (DA) has been studied in aqueous solution, under aerobic conditions, in the presence of riboflavin (Rf, vitamin B2) as a photosensitizer. Results indicate the formation of a weak dark complex Rf,DA, with a mean apparent association constant Kass = 30 m,1, only detectable at DA concentrations much higher than those employed in photochemical experiments. An intricate mechanism of competitive reactions operates upon photoirradiation. DA quenches excited singlet and triplet states of Rf, with rate constants of 4.2 × 109 and 2.2 × 109 m,1 s,1, respectively. With the catecholamine in a concentration similar to that of dissolved molecular oxygen in air-saturated water, DA and oxygen competitively quench the triplet excited state of Rf, generating superoxide radical anion (O2,,) and singlet molecular oxygen (O2(1,g)) by processes initiated by electron and energy-transfer mechanisms, respectively. Rate constants values of 1.9 × 108 and 6.6 × 106 m,1 s,1 have been obtained for the overall and reactive (chemical) interaction of DA with O2(1,g). The presence of superoxide dismutase increases both the observed rates of aerobic DA photo-oxidation and oxygen uptake, due to its known catalytic scavenging of O2,,, a species that could revert the overall photo-oxidation effect, according to the proposed reaction mechanism. As in most of the catecholamine oxidative processes described in the literature, aminochrome is the DA oxidation product upon visible light irradiation in the presence of Rf. It is generated with a quantum yield of 0.05. [source] Randomized clinical trial of the influence of local water-filtered infrared A irradiation on wound healing after abdominal surgeryBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 8 2006M. Hartel Background: Postoperative local water-filtered infrared A (wIRA) irradiation improves tissue oxygen partial pressure, tissue perfusion and tissue temperature, which are important in wound healing. Methods: The effect of wIRA irradiation on abdominal wound healing following elective gastrointestinal surgery was evaluated. Some 111 patients undergoing moderate to major abdominal surgery were randomized into one of two groups: wIRA and visible light irradiation (wIRA group) or visible light irradiation alone (control group). Uncovered wounds were irradiated twice a day for 20 min from days 2,10 after operation. Results: Irradiation with wIRA improved postoperative wound healing in comparison to visible light irradiation alone. Main variables of interest were: wound healing assessed on a visual analogue scale (VAS) by the surgeon (median 88·6 versus 78·5 respectively; P < 0·001) or patient (median 85·8 versus 81·0; P = 0·040), postoperative pain (median decrease in VAS score during irradiation 13·4 versus 0; P < 0·001), subcutaneous oxygen tension after irradiation (median 41·6 versus 30·2 mmHg; P < 0·001) and subcutaneous temperature after irradiation (median 38·9 versus 36·4 °C; P < 0·001). The overall result, in terms of wound healing, pain and cosmesis, measured on a VAS by the surgeon (median 79·0 versus 46·8; P < 0·001) or patient (79·0 versus 50·2; P < 0·001) was better after wIRA irradiation. Conclusion: Postoperative irradiation with wIRA can improve normal postoperative wound healing and may reduce costs in gastrointestinal surgery. Copyright © 2006 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] | |||||||||||||