A study of 1O2 production by immobilized sensitizer outside the solution. Measurement of 1O2 generation

Abstract— Recently, a new technique of ¹O₂ generation has been described by Midden and Wang. The sensitizer is immobilized on silica gel particles which are attached on one surface of a glass plate which is placed, sensitizer-side down, above a solution leaving a small air space between the sensitizer and the solution. Applying the principle of the technique, i.e. generation of ¹O₂ in the gas phase above the solution, we first improved the long-term stability of the dye (rose bengal) by using double stock transparent tape instead of rubber cement. Under these conditions, although the initial rate of production was higher in rubber cement, the rate of production reached a plateau after 30 min, whereas with double stick transparent tape, the rate of generation was linear up to 100 min. This result was explained by the fact that silica glass beads are embedded in the cement which could lead to the bleaching reaction of the dye. Different reactions have been investigated, the bleaching of N,N-dimethyl-4-nitrosoaniline (RNO) in the presence of imidazole, destruction of anthracenedipropionic acid, formation of a stable nitroxide from a sterically hindered secondary amine and the influence of pH on the nitroxide yield. The yield was measured to be 5 × 10¹² molecules of singlet oxygen produced per second per cm² from the surface of the plate using the RNO bleaching reaction. This method of generating ¹O₂ also seems promising for studying the killing of mammalian cells by ¹O₂ as the sole damaging species.     

Novel phenoxyalkylamine derivatives. VII. Synthesis and pharmacological activities of 2-alkoxy-5-[(phenoxyalkylamino)alkyl]benzenesulfonamide derivatives.

To find a novel alpha-blocker with high alpha-blocking selectivity against dopamine D2-receptor affinity, we performed structural modification of the alkylene chains and the substituents on two benzene rings of 2-alkoxy-5-[(phenoxyalkylamino)alkyl]benzenesulfonamide derivatives. The modification of the alkylene chain between the amino moiety in the center of the molecule and the benzene ring (ring A) was found to be the most significant. 5-[2-[[2-(5-Fluoro-2-methoxyphenoxy)ethyl]amino]propyl]-2- methoxybenzenesulfonamide (II-4), which possesses 1-methylethyl as the alkylene chain, exhibited high alpha-blocking selectivity as well as potent alpha-blocking activity.     

Toward fully synthetic carbohydrate-based HIV antigen design: on the critical role of bivalency

Synthetic gp120331-335 glycopeptide fragments carrying hybrid and high-mannose type N-linked glycans were evaluated for binding to broadly neutralizing antibody 2G12 using surface plasmon resonance technology. None of the hybrid-type constructs demonstrated binding to 2G12. In the high-mannose series, the "Cys dimer" construct, presenting two undecasaccharide glycans, showed significantly higher binding than the Cys-protected monomer. The binding of the dimeric structure was further investigated in competition with recombinant gp120. The data suggest that gp120 and its designed synthetic epitope construct bind to the same site on 2G12.     

Spectrophotometric studies on the complexation equilibria of Ni and Pb with 2-carboxy-2-hydroxy-5'-sulfo-formazylbenzene. Simultaneous determination of trace amounts of Ni and Pb

Spectrophotometric studies have been made to investigate the reaction of Nickel and Lead with 2-carboxy-2'-hydroxy-5'-sulfoformazyl-benzene (zincon) in 50%(v/v) ethanol-water at 25 degrees C and an ionic strength of 0.1 M NaClO4. A complete picture of the complexation equilibria in the pH range (4.2-12.0) for nickel and (1.9-11.5) for lead are presented. Simple, rapid, selective and sensitive methods for the spectro-photometric determination of nickel and lead has been developed based on the color reaction of their complexes with zincon. The methods allow the determination of 4.69 microg mL(-1) of nickel at pH = 6.3 (lambdamax = 665 nm) and 10.3 microg ml(-1) of lead at pH = 5.6 (lambdamax = 610 nm). The apparent molar absorptivities were epsilon = 1.3 x 10(4) L mol(-1) cm(-1) for nickel and epsilon = 0.6 x 10(4) L mol(-1) cm(-1) for lead. The interference of a large number of foreign ions and complexing agents has been studied. Thiosulphate, as masking agent allows the simultaneous determination of nickel and lead in the presence of high concentrations of copper. Ascorbic acid, sodium cyanide and or sodium fluoride provide the elimination of many other interferences. The methods have been applied successfully to the simultaneous determination of nickel and lead in an aluminium and non-ferrous alloy.     

Studies on fluorescent species of spiro-indolinonaphthooxazines and their fluorescence spectra

Photophysical behavior of spiro[1,3,3-trimethylindolino-2,3′-naphtho[2,1-b]-1,4-oxazine] (SP1) and spiro[1,3,3,2′-tetramethylindolino-2,3′-naphtho[2,1-b]-1,4-oxazine] (SP2) were studied. The fluorescent species and their spectra of SP1 and SP2 in polar solvents (acetonitrile and methanol) and non-polar solvent (cyclohexane) were investigated. The fluorescence decay in polar solvents was studied by picosecond time-correlated single photon counting. In most cases, fluorescence decay obeyed triexponential decay kinetics. The major fluorescent species is an excited intermediate which has similar conformation as its precursor (¹ SP ^*) formed after the bond cleavage between spirocarbon and oxygen in oxazine ring. The effects of molecular structure and solvent polarity on fluorescence spectra and fluorescence decay lifetime were studied.     

Optimization of zinc phosphate coating on 7075-T6 aluminum alloy

A zinc phosphate coating process on 7075-T6 aluminum alloy has been significantly improved through a combined approach of titanium colloid pretreatment, pH level adjustment, fluoride additive and ZnO/H₃PO₄ ratio adjustment. In particular, optimum phosphate coatings were formed in coating baths with a ZnO/H₃PO₄ ratio of 0.205 and 0.256. Coating morphology studied by SEM reveals that the adjustment in the coating procedure produces an improved crystalline coating layer with high coverage and small grain size. For coatings formed in a bath with a ratio of 0.205, the coverage of the crystalline patches on top of the amorphous coating base is almost complete. The chemical composition of the coating layers has been characterized by XPS and SIMS. The crystalline and amorphous coating phases formed in the bath with a ratio of 0.205 were found to have compositions given schematically as Zn_x(PO₄) and Zn_xAl_y(PO₄), respectively. In contrast, neither coating phase formed in the bath with a ratio of 0.256 shows the presence of Al.     

ViscosityB-coefficients,structural entropies and heat capacities,and the effects of ions on the structure of water

The water-structural contributions to the entropies and heat capacities of hydration of over 120 ions and the viscosity B-coefficients of nearly 80 aqueous ions are tabulated and correlated. B-coefficients for many more ions are predicted from this relationship and from their dependence on ionic size and charge. The structural entropies determine a unique scale of water structure making and breaking by the ions.     

The RS-.HSR Hydrogen Bond: acidities of alpha,omega-dithiols and electron affinities of their monoradicals

Gas-phase acidities (deltaGo(acid)) have been measured for 1,2-ethanedithiol, 1,3-propanedithiol, and 1,4-butanedithiol, using a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Adiabatic electron affinities (EAs) of the thiolate monoradicals of these compounds were assigned from electron photodetachment spectra of their corresponding thiolate monoanions, acquired using a cw-ICR. The dithiols exhibit enhanced acidities (up to 8.7 kcal/mol in deltaGo(acid)) and greater EAs (up to 6.7 kcal/mol) than analogous monothiol species. These differences are attributed to an intramolecular RS-.HSR hydrogen bond in the thiolate anion. Considerations of the RO-.HOR hydrogen bond in monoanions of alpha,omega-diols and in the [CH(3)O-.HOCH(3)] complex anion suggest that the RS-.HSR hydrogen bond provides up to 9 kcal/mol extra stabilization.     

Enhanced indoor radon concentration by using radon-rich well water in a Japanese wooden house in Fukuoka, Japan

Summary Radon measurements were carried out in a Japanese wooden house built on granitic geology, where radon-rich well water is used. Atmospheric radon concentrations were measured over one year with passive integrated radon monitors. The monitors were distributed at several locations in the house and were replaced every two months. In order to confirm the diurnal variation and heterogeneous distribution of radon, short-term measurements were carried out accordingly. Radon, its decay products and terrestrial gamma-radiations were measured in this survey. From the long-term measurement, the radon concentration in the house ranged from 14 to 184 Bq^. m^-3with an arithmetic mean of 45 Bq^. m^-3. A radon concentration of 184 Bq^. m^-3was observed in the bathroom in spring (March-May) though the radon level was normal in the living room and bedroom. In order to characterize the house, similar measurements were conducted in several surrounding houses. There was a significant difference in radon concentration between the investigated houses. There was a spatial distribution of the radon concentration and the highest value was found in the bathroom. Radon and its decay products concentrations varied with time, which increased from midnight to morning whereas they decreased during daytime. Although the radon concentration in tap water was 1 Bq^. l^-1, a high level of 353 Bq^. l^-1was found in the well water.While well water was being used, the indoor radon concentration near the bathroom increased rapidly with a maximum value of 964 Bq^. m^-3. It is clear that the use of well water enhanced the radon level around the bathroom.     

Isolation from Gluconacetobacter diazotrophicus cell walls of specific receptors for sugarcane glycoproteins, which act as recognition factors

Glycoproteins from sugarcane stalks have been isolated from plants field-grown by size-exclusion chromatography. Some of these glycoproteins, previously labelled with fluorescein isothiocyanate, are able to bind to the cell wall of the sugarcane endophyte, N2-fixing Gluconacetobacter diazotrophicus, and largely removed after washing the bacterial cells with sucrose. This implies that sugarcane glycoproteins use beta-(1-->2)-fructofuranosyl fructose domains in their glycosidic moiety to bind to specific receptors in the bacterial cell walls. These receptors have been isolated by affinity chromatography on a sugarcane glycoprotein-agarose matrix, desorbed with sucrose and characterized by sodium dodecyl sulfate polyacrylamide gel electrophresisand capillary electrophoresis (CE).