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LoSecco JM Bionta RM Biewitt G Bratton CB Casper D Chrysicopoulou P Claus R Cortez BG Errede S Foster GW Gajewski W Ganezer KS Goldhaber M Haines TJ Jones TW Kielczewska D Kropp WR Learned JG Lehmann E Park HS Reines F Schultz J Seidel S Shumard E Sinclair D Sobel HW Stone JL Sulak L Svoboda R van der Velde JC Wuest C 《Physical review letters》1985,54(21):2299-2301
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Abstract— The triplet state characteristics (spectrum, lifetime and quantum yield) for four dye sensi tisers [methylene blue (MB), erythrosin (ER), haematoporphyrin (HP) and riboflavin (RF)] were determined in methanol by laser flash photolysis and singlet oxygen yields (0.60 to 0.48) from time-resolved measurements of the 1270 nm near infrared emission. The reaction of singlet oxygen with four long chain unsaturated phenyl esters [oleate (18: 1), linoleate (18: 2), linolenate (18: 3) and arachidonate (20: 4)] was followed quantitatively using the singlet oxygen luminescence technique and also, after continuous420–700 nm irradiation, by HPLC and other analysis of the isomeric product monohydroperoxides. The overall quantum yield of photooxidation (∼10-2 ) was shown to be consistent with the observed singlet oxygen quenching constants(2–12 times 104 dm3 mol-1 s-1 ) for the four esters studied and the singlet oxygen lifetime in methanol (τ∼ 9 μs). The isomer product distribution was interpreted in terms of a dual singlet oxygen and radical mechanism, the radical contribution increasing with sensitiser in the order ER = MB < HP ≪ RF, but also showing some dependence on substrate unsaturation. Evidence is presented for singlet oxygen quenching by MB and RF ( kO = 1.6 and 6.0 times 107 dm3 mol-1 s-1 ) and for the accelerated photobleaching of the dye sensitisers in the presence of the unsaturated esters. 相似文献
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Stockman RA Sinclair A Arini LG Szeto P Hughes DL 《The Journal of organic chemistry》2004,69(5):1598-1602
An entirely two-directional synthesis of (+/-)-perhydrohistrionicotoxin is presented, utilizing a tandem oxime formation/Michael addition/[3 + 2] cycloaddition as the key step. This approach also constitutes formal syntheses of (+/-)-histrionicotoxin and (+/-)-histrionicotoxin 235A. 相似文献
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W.Robert Sinclair J.B. Macchesney P.K. Gallagher P.B. O''Connor 《Thermochimica Acta》1979,30(1-2):225-231
The reaction between SiCl4 and O2 at 1 atm between 25 and 1200°C has been followed by mass spectrometry. Below 600°C no reaction with O2 is noted. Above 600°C the reaction proceeds in two steps. Between 800 and 1000°C the 28Si/32O2 peak height ratio is constant with no evolution of Cl2. It is suggested that silicon oxychlorides are being formed in this temperature regime. Above 1000°C the reaction between SiCl4 and O2 intensifies with concomitant production of Cl2. It is suggested that above 1000°C the reaction SiCl4 + O2 → SiO2 + Cl2 becomes important.
At low temperatures (<800°C) adsorbed H2O and OH groups from the surface of the fused silica tube react with SiCl4 to form HCl. The importance of this reaction decreases with increasing temperature. The increased production of HCl above 1000°C is ascribed to H2O and H2 diffusing from the tube. 相似文献
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Christopher D. Sinclair 《Monatshefte für Mathematik》2012,166(1):121-144
We give a hyperpfaffian formulation of partition functions and ensemble averages for Hermitian and circular ensembles when L is an arbitrary integer and ???=?L 2 and when L is an odd integer and ???=?L 2?+?1. 相似文献