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Absorption Peaks (absorption + peak)
Selected AbstractsThe Influence of Alkyl-Chain Length on Beta-Phase Formation in PolyfluorenesADVANCED FUNCTIONAL MATERIALS, Issue 1 2009Daniel W. Bright Abstract Di- n -alkyl substituted polyfluorenes with alkyl chain lengths of 6, 7, 8, 9, and 10 carbon atoms (PF6, PF7, PF8, PF9, and PF10) are studied in dilute solution in MCH using optical spectroscopy. Beta-phase is formed upon cooling in solutions (, 7,µg mL,1) of PF7, PF8, and PF9 only, which is observed as an equilibrium absorption peak at , 437,nm and strong changes in the emission spectra. Beta-phase is formed upon thermal cycling to low temperature in solutions (,7,µg mL,1) of PF7, PF8, and PF9, which is observed as an equilibrium absorption peak at , 437,nm and strong changes in the emission spectra. Beta phase is found to occur more favorably in PF8 than in PF7 or PF9, which is attributed to a balance between two factors. The first is the dimer/aggregate formation efficiency, which is poorer for longer (more disordered) alkyl chain lengths, and the second is the Van der Waals bond energy available to overcome the steric repulsion and planarize the conjugated backbone, which is insufficient in the PF6 with a shorter alkyl chain. Beta phase formation is shown to be a result of aggregation, not a precursor to it. A tentative value of the energy required to planarize the fluorene backbone of (15.6,±,2.5) kJ mol,1 monomer is suggested. Excitation spectra of PF6, PF7, PF8, and PF9 in extremely dilute (, 10,ng mL,1) solution show that beta phase can form reversibly in dilute solutions of PF7, PF8 and PF9, which is believed to be a result of chain collapse or well dispersed aggregates being present in solution from dilution of more concentrated solutions. PF7, PF8, and PF9 also form beta phase in thermally cycled solid films spin-cast from MCH. However, in the films the PF7 formed a larger fraction of beta phase than the PF9, in contrast to the case in solutions, because it is less likely that the close-packed chains in the solid state will allow the formation of planarized chains with the longer PF9 side chains. [source] Design of Multilayered Nanostructures and Donor,Acceptor Interfaces in Solution-Processed Thin-Film Organic Solar Cells,ADVANCED FUNCTIONAL MATERIALS, Issue 10 2008Hiroaki Benten Abstract Multilayered polymer thin-film solar cells have been fabricated by wet processes such as spin-coating and layer-by-layer deposition. Hole- and electron-transporting layers were prepared by spin-coating with poly(3,4-ethylenedioxythiophene) oxidized with poly(4-styrenesulfonate) (PEDOT:PSS) and fullerene (C60), respectively. The light-harvesting layer of poly-(p -phenylenevinylene) (PPV) was fabricated by layer-by-layer deposition of the PPV precursor cation and poly(sodium 4-styrenesulfonate) (PSS). The layer-by-layer technique enables us to control the layer thickness with nanometer precision and select the interfacial material at the donor,acceptor heterojunction. Optimizing the layered nanostructures, we obtained the best-performance device with a triple-layered structure of PEDOT:PSS|PPV|C60, where the thickness of the PPV layer was 11,nm, comparable to the diffusion length of the PPV singlet exciton. The external quantum efficiency spectrum was maximum (ca. 20%) around the absorption peak of PPV and the internal quantum efficiency was estimated to be as high as ca. 50% from a saturated photocurrent at a reverse bias of ,3,V. The power conversion efficiency of the triple-layer solar cell was 0.26% under AM1.5G simulated solar illumination with 100,mW,cm,2 in air. [source] Insecticidal activities of secondary metabolites of endophytic Pencillium sp. in Derris elliptica BenthJOURNAL OF APPLIED ENTOMOLOGY, Issue 8 2005M. Y. Hu Abstract:, A strain of endophytic Pencillium sp., which might produce rotenone or its analogues and showed bioactivity against aphids, was isolated from the fresh roots of Derris elliptica Benth. A total of 12 fractions, isolated from the chloroform extract of endophytic Pencillium sp. mycelia by silica gel column, were tested by bioassay and high-performance liquid chromatography (HPLC), and the more bioactive fractions were found to be D, E and J. Against the adult turnip aphid, Lipaphis erysimi, by dipping at a concentration of 1 mg/ml, the corrected mortalities of fraction D, E and J were 57.68, 63.28 and 69.74% after 48 h of treatment respectively. The three fractions also showed strong antifeeding activity against third instar larvae of Plutella xylostella in a laboratory bioassay. One absorption peak was detected in the HPLC picture of fraction D, it had a similar retention time as that of rotenone, and the chemical constituent, related to the absoption peak, had the same ultraviolet absorption picture as that of rotenone. Then it could be further concluded that the bioactive compounds in the fraction D could be rotenone or its analogous compounds. [source] Thermal and dynamic mechanical properties of organic,inorganic hybrid composites of itaconate-containing poly(butylene succinate) and methacrylate-substituted polysilsesquioxaneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Takenori Sakuma Abstract Itaconate-unit-containing poly(butylene succinate) (PBSI) was synthesized by the reaction of 1,4-butanediol, succinic acid, and itaconic acid in a molar ratio of 2.0 : 1.0 : 1.0, and the obtained PBSI was reacted with methacryl-group-substituted polysilsesquioxane (ME-PSQ) in the presence of benzoyl peroxide (BPO) at 130°C to produce PBSI/ME-PSQ hybrid composites. The thermal and dynamic mechanical properties of the PBSI/ME-PSQ hybrid composites were investigated in comparison with those of PBSI cured at 130°C in the presence of BPO. As a result, the hybrid composites showed a much higher thermal degradation temperature and storage modulus in the rubbery state than the cured PBSI (C-PBSI). The thermal degradation temperature and storage modulus of the hybrid composites increased with increasing ME-PSQ content. The glass-transition temperature, measured by dynamic mechanical analysis of the hybrid composites, somewhat increased with increasing ME-PSQ content. However, the glass-transition temperatures of all the hybrid composites were lower than that of C-PBSI. Although the IR absorption peak related to CC groups was not detected for C-PBSI, some olefinic absorption peaks remained for all the hybrid composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Novel two-dimensional donor,acceptor conjugated polymers containing quinoxaline units: Synthesis, characterization, and photovoltaic propertiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2008Lijun Huo Abstract Novel two-dimensional donor,acceptor (D,A) structured conjugated polymers, P1,P4, were designed and synthesized by introducing electron-deficient quinoxaline as core and electron-rich alkoxyl-phenylenevinylene in side chains and p -phenylenevinylene, triphenylamine, or thiophene in main chain. Benefited from the D,A structures, the polymers possess low bandgaps of 1.75 eV, 1.86 eV, 1.59 eV, and 1.58 eV for P1, P2, P3, and P4, respectively, and show broad absorption band in the visible region: the shorter wavelength absorption peak at ,400 nm ascribed to the conjugated side chains and the longer wavelength absorption peak between 500 nm and 750 nm belonging to the absorption of the conjugated main chains. Especially, the absorption band of P4 film covers the whole visible range from 300 nm to 784 nm. The power conversion efficiencies of the polymer solar cells based on P1,P4 as donor and PCBM as acceptor are 0.029%, 0.14%, 0.46%, and 0.57%, respectively, under the illumination of AM 1.5, 100 mW/cm2. The polymers with the low bandgap and broad absorption band are promising photovoltaic materials. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4038,4049, 2008 [source] Experimental and theoretical evidence for the chemical mechanism in SERRS of rhodamine 6G adsorbed on colloidal silver excited at 1064 nmJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2010Bin Dong Abstract The evidence for the existence of a chemical mechanism in surface-enhanced resonance Raman scattering (SERRS) of rhodamine 6G (R6G) adsorbed on colloidal silver excited at 1064 nm is reported on the basis of experimental and theoretical analyses. A weak absorption peak at around 1060 nm for R6G-functionalized silver nanoparticles was observed, which is not present in the individual spectra of R6G or silver nanoparticles. Theoretically, the charge difference density reveals that this weak absorption is a metal-to-molecule charge transfer excited state. Copyright © 2010 John Wiley & Sons, Ltd. [source] CP43,, the isiA Gene Product, Functions as an Excitation Energy Dissipator in the Cyanobacterium Synechococcus sp.PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2001PCC 794 ABSTRACT Under conditions of iron deficiency certain cyanobacteria induce a chlorophyll (Chl)-binding protein, CP43,, which is encoded by the isiA gene. We have previously suggested that CP43, functions as a nonradiative dissipator of light energy. To further substantiate its functional role an isiA overexpression construct was introduced into the genome of a cyanobacterium Synechococcus sp. PCC 7942 (giving isiAoe cells). The presence of functional CP43, in isiAoe cells was confirmed by Western blot as well as by the presence of a characteristic blueshift of the red Chl a absorption peak and a notable increase in the 77 K fluorescence peak at 685 nm. Compared to wild-type cells isiAoe cells, with induced CP43,, had both smaller functional antenna size and decreased yields of room temperature Chl fluorescence at various light irradiances. These observations strongly suggest that isiAoe cells, with induced CP43,, have an increased capacity for dissipating light energy as heat. In agreement with this hypothesis isiAoe cells were also more resistant to photoinhibition of photosynthesis than wild-type cells. Based on these results we have further strengthened the hypothesis that CP43, functions as a nonradiative dissipator of light energy, thus protecting photosystem II from excessive excitation under iron-deficient conditions. [source] Structure and energy of partial dislocations in wurtzite-GaNPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2007G. Savini Abstract First-principle calculations have shown that both the partials can be electrically active. In particular we have shown the Ga(g) core partials are a good candidate for the observed absorption peak at 2.4 eV revealed by energy loss spectroscopy measurements. The symmetric and asymmetric reconstructions have relatively close formation energies. Our results have suggested that the asymmetric reconstructions, characterized by strong bonds along the dislocation line are favourable in intrinsic materials. However, in strongly p and n-type materials or in high stress field the symmetric reconstructions can become energetically more stable. These reconstructions are always electrically active with a deep band across the forbidden gap. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Carbon Nanotubes Functionalized in Oxygen and Water Low Pressure Discharges used as Reinforcement of Polyurethane CompositesPLASMA PROCESSES AND POLYMERS, Issue S1 2009Lenka Zají, ková Abstract The functionalization of multi-walled CNTs in O2/Ar and H2O/Ar low pressure capacitive discharges was studied by XPS and FT-IR. The pristine and functionalized CNTs were used as fillers in polyurethane paints. Successful plasma functionalization was confirmed by changes in atomic composition and chemical shift of the XPS atomic signals. The functionalization was indicated also by the shift of IR absorption peaks corresponding to the motion of carbon skeleton, especially the peak at about 1,560,cm,1. The presence of carbonyl was confirmed by IR absorption peak at 1,723,cm,1 only for O2/Ar plasma. The plasma functionalized CNTs increased significantly the universal and plastic hardness of the CNTs reinforced polyurethane as compared to the composites with pristine CNTs. [source] Photoluminescent behavior of poly(3-hexylthiophene) derivatives with a high azobenzene content in the side chainsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 5 2005Xiongyan Zhao Abstract A series of polythiophene derivatives with substantially higher azobenzene contents in the side chains were prepared via copolymerization of 3-hexylthiophene with four different types of 4-((4-(phenyl)azo)phenoxy)alkyl-3-thienylacetate. The alkyl spacers with different lengths, i.e. butyl, hexyl, octyl and undecyl groups were used between the azobenzene group and the thiophene ring. The compositions, structures and thermal properties of these polythiophene derivatives were characterized. The structural dependence of photoluminescent emission, photochromic behavior of these copolymers were systematically studied and compared with poly(3-hexylthiophene). The results show that the azobenzene substitution renders the polythiophene some interesting optical properties that can be modulated by UV light irradiation. In the azobenzene modified polythiophene, the intensity of photoluminescent emission associated with the conjugated polythiophene main chain was found to decrease significantly upon UV irradiation. The finding suggests that the photo-induced trans - cis isomerization of the azobenzene pendant groups has a significant effect on photoluminescent emission, particularly when short spacers are used between azobenzene groups and the main chain. However, the effect becomes less prominent when longer spacers are used between the azobenzene group and the main chain. Furthermore, UV irradiation of the copolymers also resulted in an increase in intensity and broadening of bandwidth for the absorption peak associated with the polythiophene backbones. Again the magnitude of intensity changes upon UV irradiation were found to be dependent on the spacer length between the azobenzene group and polythiophene main chain. Copyright © 2005 John Wiley & Sons, Ltd. [source] Cloning, purification, crystallization and preliminary crystallographic studies of Bradyrhizobium fucosyltransferase NodZACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2004Krzysztof Brzezinski The ,-1,6-fucosyltransferase NodZ from Bradyrhizobium sp. WM9 (Lupinus), composed of 325 amino acids with a molecular weight of 37,kDa, has been cloned, expressed and purified. Protein crystals suitable for X-ray diffraction were obtained under optimized crystallization conditions using ammonium dihydrogen phosphate as a precipitant. The crystals are hexagonal and belong to space group P6122 or P6522, with unit-cell parameters a = 125.5, c = 95.6,Å, and contain 56.8% solvent and a single protein molecule in the asymmetric unit. Native data were collected to 2.85,Å using synchrotron radiation and cryogenic conditions. The native crystals were soaked in a mother-liquor solution containing 2.5,mM [Ta6Br12]2+ cluster for derivatization and SAD data were collected to 3.4,Å at the tantalum LIII absorption peak. [source] Purification and properties of a new Brevibacterium sterolicum cholesterol oxidase produced by E. coli MM294/pnH10FEMS MICROBIOLOGY LETTERS, Issue 2 2002Kinya Fujishiro Abstract A gene encoding a cholesterol oxidase from Brevibacterium sterolicum nov. sp. ATCC21387 was isolated by an expression cloning method and highly expressed by a recombinant strain Escherichia coli MM294/pnH10. The purified cholesterol oxidase was a typical flavoprotein with a molecular mass of 46.5 kDa, absorption peaks at 280, 360, and 450 nm. Optimum pH and temperature were found at pH 6.5 and 55°C, respectively. The enzyme acted on 3,-hydroxysteroids such as cholesterol, pregnenolone, and ,-sitosterol at high rates, but on dehydro- epi -androsterone to a lesser degree. The molecular and catalytic properties were different from those of cholesterol oxidase I, which was initially discovered in B. sterolicum nov. sp. ATCC21387. The new enzyme, designated cholesterol oxidase II, was distinguished by its high affinity toward cholesterol (Km= 30,M). [source] Linear and Nonlinear Optical Properties of Ag Nanowire Polarizing Glass,ADVANCED FUNCTIONAL MATERIALS, Issue 18 2006Q.-Q. Wang Abstract An R2O,B2O3,SiO2 (R,=,Li, Na, K) polarizing glass containing Ag nanorods is prepared by thermal elongation,reduction technology. The transverse and longitudinal plasmon absorption peaks of the embedded Ag nanorods are near 460 and 720,nm, respectively. When the polarization of the laser is parallel to the long axis of the Ag nanorods, the nonlinear absorption coefficient ,,=,0.82,cm,GW,1 and the nonlinear refractive index n2,=,,1.5,×,10,4,cm2,GW,1. When the polarization of light is perpendicular to the long axis of the Ag nanorods ,,=,0.12,cm,GW,1 and n2,=,,7.2,×,10,5,cm2,GW,1 and the appropriate one- and two-photon figures of merit (FOM), W,=,1.6 and T,=,0.16, respectively, are obtained, which satisfies the demand, W,>,1 and T,<,1, for applications in all optical switching, where W is a one-photon FOM, and T is a two-photon FOM. [source] Thermal and dynamic mechanical properties of organic,inorganic hybrid composites of itaconate-containing poly(butylene succinate) and methacrylate-substituted polysilsesquioxaneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Takenori Sakuma Abstract Itaconate-unit-containing poly(butylene succinate) (PBSI) was synthesized by the reaction of 1,4-butanediol, succinic acid, and itaconic acid in a molar ratio of 2.0 : 1.0 : 1.0, and the obtained PBSI was reacted with methacryl-group-substituted polysilsesquioxane (ME-PSQ) in the presence of benzoyl peroxide (BPO) at 130°C to produce PBSI/ME-PSQ hybrid composites. The thermal and dynamic mechanical properties of the PBSI/ME-PSQ hybrid composites were investigated in comparison with those of PBSI cured at 130°C in the presence of BPO. As a result, the hybrid composites showed a much higher thermal degradation temperature and storage modulus in the rubbery state than the cured PBSI (C-PBSI). The thermal degradation temperature and storage modulus of the hybrid composites increased with increasing ME-PSQ content. The glass-transition temperature, measured by dynamic mechanical analysis of the hybrid composites, somewhat increased with increasing ME-PSQ content. However, the glass-transition temperatures of all the hybrid composites were lower than that of C-PBSI. Although the IR absorption peak related to CC groups was not detected for C-PBSI, some olefinic absorption peaks remained for all the hybrid composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Blending of NR/BR/EPDM by reactive processing for tire sidewall applications.JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Abstract Cure incompatibility in NR/BR/EPDM blends is a crucial problem, affecting blend properties. In a previous study, it was demonstrated that the mechanical properties of such blends can be significantly improved by utilizing a reactive processing technique, in which a pretreated EPDM is first prepared by incorporating all compounding ingredients in the EPDM and subsequent preheating, prior to crossblending with premasticated NR/BR. In the present article, the pretreated EPDM-moieties are prepared using two different accelerators, N -cyclohexyl-2-benzothiazole sulfenamide (CBS) and 6-nitro MBTS. The latter was synthesized and applied for the purpose of IR characterization. The infrared (IR) spectra of the pretreated, extracted EPDM demonstrate absorption peaks associated with the IR absorption of the functional groups in the accelerator fragments, attached to the EPDM. NR/BR/EPDM (35/35/30) ternary blends are prepared by reactive mixing of the pretreated EPDM with CBS fragments attached with premasticated NR/BR on a two-roll mill. Their blend morphological features are studied using the atomic force microscopy (AFM) and transmission electron microscopy (TEM) microscopic techniques, in comparison with those of blends prepared by a conventional straight mixing method. Both the tapping mode AFM phase images and TEM micrographs clearly show that reactive mixing leads to more homogeneous blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:2547,2554, 2007 [source] Effect of side-chain end groups on the optical, electrochemical, and photovoltaic properties of side-chain conjugated polythiophenesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2006Erjun Zhou Abstract Three new side-chain conjugated polythiophene derivatives, poly{3-[2-(3-methoxy-4-octyloxy-phenyl)-vinyl]-thiophene} (P3MOPVT), poly{3-[2-(3,5-dimethoxy-4-octyloxy-phenyl)-vinyl]-thiophene} (P3DMOPVT), and poly{3-[2-(3,4-dioctyloxy-phenyl)-vinyl]-thiophene} (P3DOPVT), were synthesized by Wittig-Hornor reaction and GRIM method and compared with poly{3-[2-(4-octyloxy-phenyl)-vinyl]-thiophene} (P3OPVT) for investigating the effect of the end groups of the conjugated side-chain on the properties of the polymers. Owing to the electron-donating ability of methoxy groups, the visible absorption peaks of P3MOPVT and P3DMOPVT solutions and films become stronger and red-shifted compared with P3OPVT. The electrochemical bandgaps of the four polymers are 2.15 eV for P3OPVT, 1.99 eV for P3MOPVT, 1.85 eV for P3DMOPVT, and 2.36 eV for P3DOPVT, respectively, which indicate that the electron-donating ability of the methoxy end group on the conjugated side chain of P3MOPVT and P3DMOPVT and the large steric hindrance of the two octyloxy end groups on the conjugated side chain of P3DOPVT have obvious influence on the electrochemical properties of the side-chain conjugated polythiophenes. Polymer solar cells were fabricated with a structure of ITO/PEDOT:PSS/Polymer:PCBM/LiF/Al. The best device, based on P3DMOPVT, shows a power conversion efficiency of 1.63% under the illumination of AM1.5, 80 mW/cm2. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4916,4922, 2006 [source] Novel family of triphenylamine-containing, hole-transporting, amorphous, aromatic polyamides with stable electrochromic propertiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2005Tzy-Hsiang Su Abstract We report the preparation and characterization of a series of novel electrochromic, aromatic poly(amine amide)s with pendent triphenylamine units. The synthesis proceeded via direct phosphorylation polycondensation between a novel diamine, N,N -bis(4-aminophenyl)- N,,N,-diphenyl-1,4-phenylenediamine, and various aromatic dicarboxylic acids. All the poly(amine amide)s were amorphous and readily soluble in many common organic solvents and could be solution-cast into transparent, tough, and flexible films with good mechanical properties. They exhibited good thermal stability and 10% weight-loss temperatures above 540 °C. Their glass-transition temperatures were 263,290 °C. These polymers in N -methyl-2-pyrrolidinone solutions exhibited strong ultraviolet,visible absorption peaks at 307,358 nm and photoluminescence peaks around 532,590 nm in the green region. The hole-transporting and electrochromic properties were studied with electrochemical and spectroelectrochemical methods. Cyclic voltammograms of poly(amine amide) films prepared by the casting of polymer solutions onto an indium tin oxide coated glass substrate exhibited two reversible oxidation redox couples at 0.65 and 1.03 V versus Ag/AgCl in an acetonitrile solution. All the poly(amine amide)s showed excellent stability with respect to their electrochromic characteristics; the color of the films changed from pale yellow to green and then blue at 0.85 and 1.25 V, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2085,2098, 2005 [source] Linking Polythiophene Chains Through Conjugated Bridges: A Way to Improve Charge Transport in Polymer Solar CellsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 10 2006Erjun Zhou Abstract Summary: A series of cross-linked polythiophene derivatives (P1,4) are synthesized by adding different ratio (0, 2, 5, and 10%) of conjugated cross-linker via a Stille coupling reaction. From P1,4, with the increase of the content of the conjugated bridges, the UV-visible absorption peaks of the polymers were shifted towards blue and their electrochemical bandgap increased. The hole mobilities of P1,4 as determined from the SCLC model are 5.23,×,10,6, 1.28,×,10,4, 7.01,×,10,3, and 2.34,×,10,5 cm2,·,V,1,·,s,1, respectively. The PCEs of the polymer solar cells based on P1,4 are 0.37, 1.05, 1.26, and 0.78%, respectively. The improvement of PCE of the devices based on P2,4 compared with that of P1 may be due to the increase of hole mobility. Molecular structure of the polythiophene derivatives (P1,4). [source] Evaluation of the Photosensitizer Tookad® for Photodynamic Therapy on the Syrian Golden Hamster Cheek Pouch Model: Light Dose, Drug Dose and Drug,light Interval Effects,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2003François Borle ABSTRACT We have evaluated the efficacy of the new photosensitizer (PS) Tookad® in photodynamic therapy (PDT) in vivo. This PS is a palladium-bacteriopheophorbide presenting absorption peaks at 762 and 538 nm. The light dose, drug dose and drug injection,light irradiation interval (DLI), ranging between 100 and 300 J/cm2, 1 and 5 mg/kg and from 10 to 240 min, respectively, were varied, and the response to PDT was analyzed by staging the macroscopic response and by the histological examination of the sections of the irradiated cheek pouch. The level of PDT response, macroscopically and histologically, shows a strong dependence on the DLI, light dose and drug dose at the applied conditions in the normal hamster cheek pouch. A decay of the tissular response with increasing DLI is observed corresponding to a time of half-maximum response ranging from 10 to 120 min, depending on drug dose and light dose. The tissues affected at the lowest doses are predominantly the vascularized diffuse connective tissue situated between the inner and outer striated muscle (SM) layers as well as these muscle layers themselves. The highest response at the shortest DLI and the absence of a measurable response at DLI longer than 240 min at 300 J/cm2 and drug dose of 5 mg/kg are characteristics of a predominantly vascular effect of this PS. This observation suggests that Tookad® could be effective in PDT of vascularized lesions or pathologies associated with the proliferation of neovessels. [source] Pressure dependence of the optical properties of wurtzite and rock-salt Zn1,xCoxO thin filmsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2007J. A. Sans Abstract In this paper we investigate the electronic structure of Zn1,xCoxO by means of optical absorption measurements under pressure. Thin films of Zn1,xCoxO with different Co content (from 1 to 30%) were prepared by pulsed laser deposition on mica substrates. Absorption spectra exhibit three main features that are clearly correlated to the Co content in the films: (i) absorption peaks in the infrared associated to crystal-field-split internal transitions in the Co 3d shell, with very small pressure coefficients due to their atomic character; (ii) a broad absorption band below the fundamental edge associated to charge transfer transitions, that exhibit relatively large pressure coefficients, indicating that the Co 3d final states must be strongly hybridized to the conduction band; and (iii) a blue-shifted fundamental absorption edge associated to band to band transitions with a pressure coefficient close to that of pure ZnO. In the up-stroke the transition pressure from wurtzite to rock-salt phase decrease almost linearly as the Co increases, from 9.5 GPa in pure ZnO to about 6.5 GPa for x = 30%. In the down-stroke pressure we observe a similar behavior, yielding a metastable rock-salt phase at room pressure, after a pressure cycle up to 15 GPa. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Adsorption of benzene over the rutile TiO2 (110) surfaces: A theoretical studyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2010A. R. R. Neto Abstract In this work, we present our theoretical results for the relaxation of the rutile TiO2 (110), as well as for the adsorption of benzene over this surface. Our results are in good agreement with both the available theoretical and experimental data, whenever these comparisons were possible. Based on our obtained results, we show that the interaction between the adsorbate and the TiO2 (110) surface shows a van der Waalslike character, with the calculated adsorption energies at the order of 43 to 173 meV. In this adsorption process, the H atoms of the benzene prefer to bind with the surface Ti atoms. As a result, two occupied electronic levels appear at the surface bandgap, which are responsible for the optical absorption peaks at the blue-violet region of the electromagnetic spectra. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical properties of InAs/InP quantum dot stack grown by metalorganic chemical vapor depositionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003Heedon Hwang Abstract The 5-layer InAs quantum dot (QD) stack was grown on an (001) InP substrate by low pressure-metalorganic chemical vapor deposition. 40 nm InP spacer layers were inserted between the InAs QDs. The integrated intensity of the photoluminescence peak at 300 K was over 12% of that at 10 K. Far-infrared absorption peaks were observed at 819 cm,1 (101.64 meV) and 518 cm,1 (64.08 meV) from this structure at room temperature by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Raman analysis showed that the peak at 819 cm,1 was attributed to a plasmon related peak in the n-type InP substrate. The absorption peak at 518 cm,1 was regarded as a peak related with intersubband transition in the InAs QDs, suggesting that room temperature operating quantum dot devices may be fabricated. [source] Fabrication of micropatterns with dyes in polymer films by selective doping of dye vapor in a vacuum,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11-12 2006Toshiko Mizokuro Abstract In this article a novel process for patterning of dye into a positive-type novolac resin is reported by doping vapor of the blue dye, Solvent Blue 59 (SB59), using a simple vacuum process named the vapor transportation method. SB59-doped novolac resin films were examined by UV-vis absorption spectroscopy and optical microscopy. When SB59 vapor was doped into unexposed films at temperatures above 130°C, absorption peaks due to SB59 were detected. In contrast, no absorption peaks were detected when SB59 vapor was doped into exposed films. These results indicated the selective doping of SB59 vapor into unexposed novolac resin films. When SB59 vapor reached the surfaces of micropatterned novolac resin films with both unexposed and exposed areas, SB59 was doped selectively into the unexposed areas of the films, resulting in the production of micropatterns with SB59 molecules in the patterned films. Copyright © 2006 John Wiley & Sons, Ltd. [source] Characterization of isoquinoline alkaloids, diterpenoids and steroids in the Chinese herb Jin-Guo-Lan (Tinospora sagittata and Tinospora capillipes) by high-performance liquid chromatography/electrospray ionization with multistage mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 15 2006Yufeng Zhang This study sought to determine the primary components (isoquinoline alkaloids, diterpenoids and steroids) in crude extracts of the Chinese herb Jin-Guo-Lan, prepared from the roots of Tinospora sagittata and T. capillipes, by liquid chromatography/electrospray ionization multistage mass spectrometry coupled with diode-array detection (LC-DAD/ESI-MSn). After separation on a reversed-phase C18 column using gradient elution, positive and negative ESI-MS experiments were performed. In positive ion mode, the three types of compounds showed very different characteristic ions: strong [M]+ or [M+H]+ ions were observed for isoquinoline alkaloids; [M+NH4]+ and/or [M+HCO2]+ for diterpenoids; [M+HnH2O]+ (n=1,3) for steroids. These adduct ions and/or fragments were used to deduce the mass and categories of known and unknown components in crude extracts, and their structures were further confirmed by ESI-MSn in positive ion mode. Moreover, UV absorption peaks obtained from DAD provided useful functional group information to aid the MSn -based identification. As a result, 11 compounds were unambiguously identified by comparing with standard compounds and 13 compounds were tentatively identified or deduced according to their MSn data. Two of these compounds (13-hydroxycolumbamine and 13-hydroxyjatrorrhizine) were found to be new compounds and another one (13-hydroxypalmatine) was detected for the first time as a natural product. In addition, a [M·CH3H2O].+ ion in MS2 of [M]+ after in-source collision-induced dissociation was used to differentiate positional isomers of protoberberine alkaloids, columbamine and jatrorrhizine. Although the roots of T. sagittata and T. capillipes contain almost identical compounds, the content of the compounds in them is dramatically different, suggesting the necessity for further comparison of the bioactivities of the two species. Copyright © 2006 John Wiley & Sons, Ltd. [source] Pharmacokinetics and metabolism of neferine in rats after a single oral administrationBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 7 2007Ying Huang Abstract The present study utilized HPLC and LC-MS approaches to investigate the pharmacokinetics and metabolism of neferine (a bisbenzylisoquinoline alkaloid). The plasma concentration-time curves of neferine (10, 20 and 50 mg/kg, i.g.) showed double absorption peaks with the first peak at 10 min and the second peak at 1 h. The t was 15.6 h, 22.9 h and 35.5 h, for each of these doses, respectively. Neferine distributed rapidly into different organ systems, with the highest concentrations found in the liver, followed by the lung, kidney and heart at doses of 10 or 20 mg/kg. At 50 mg/kg dose, concentrations of the kidney and lung were higher than those of others. Moreover, this compound was mainly metabolized in the liver and converted partially by CYP2D6 to liensinine, isoliensinine, desmethyl-liensinine and desmethyl-isoliensinine. Copyright © 2007 John Wiley & Sons, Ltd. [source] Fluorescence Quenching of Pheophytin-a by Copper(II) IonsCHINESE JOURNAL OF CHEMISTRY, Issue 3 2009Mingbo HU Abstract A method was developed for determination of Cu(II) ions quantitatively by measuring fluorescent intensity of pheophytin-a (Pheoa) solution. The Pheoa was obtained by de-intercalation of magnesium from the porphyrin ring of chlorophyll-a (Chla) extracted from fresh spinach leaves. Its two UV-Vis absorption peaks at 505 and 535 nm in acetone solution have been observed but disappeared when the acetone solution of Pheoa was mixed with a Cu(II) ion aqueous solution. A fluorescence quenching phenomenon was thus observed when the acetone solution of Pheoa was mixed with an aqueous solution of Cu(II) ions. However, other physiologically relevant cations rarely caused any quenching fluorescence of Pheoa under the same experimental conditions. Kinetics of the fluorescence fading process was investigated by measuring the effects of Cu(II) ion concentration, reaction time and reaction temperature on the fluorescence intensity of the Pheoa acetone solution. An activation energy of (10±1) kJ·mol,1 was estimated from Arrhenius empirical relation assuming that the interaction between the Pheoa and the Cu(II) ions was the first order reaction. The calibration graph obtained with the fluorescence was linear over the Cu(II) concentration range of 8.0×10,5,8.0×10,7 mol·dm,3 with a detection limit of 8.0×10,7 mol·dm,3 for Cu(II) ion. [source] | |||||||||||||||||||