THE NATURE AND SOURCE OF ESR SIGNAL IN BILIRUBIN

The ESR signals of bilirubin-IXα were studied including the samples treated with free radical generating and inhibiting systems, i.e.X-X0., Fe/EDTA, SOD, mannitol/ascorbate, DTPA, KCN et al.These stable signals all comprise those originated from a semiquinone radical(g=2.0012)and superoxide radical(g₁₁=2.041, g_⊥=2.0040).The latter is shown to be bound with metal ionsespecially iron, chelated by bilirubin.The iron probably comes from bilirubin precursor---hemootobin.Active oxygen free radical scavengers may destroy these radicals.Kinetic curves of regeneration of the bilirubin radicals have been determined.Bilirubin is discussed as"active oxygen trap"in mammatians.     

Interaction between Metal in Metallo Enzyme and Small Biological Molecules

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Cooling rate dependence of specific heat in systems out of equilibrium

The anomaly of specific heat in systems out of equilibrium, especially the measurement procedure dependence of specific heat, is investigated by means of free energy landscape. Introducing measurement procedure which is based on experimental method, we propose a calculation method of specific heat in systems out of equilibrium and find an abrupt change in specific heat between annealed and quenched states. For longer observation time the change in specific heat occurs at lower temperature and becomes sharper. For slower cooling of a system the transition temperature becomes lower. This cooling rate dependence of the transition temperature is consistent with experiments and thus the abrupt change in specific heat can be regarded as the glass transition which is thermally identified.     

The Unusual Spectrum of the Mixture of Tin-octabutoxy Naphthalocyanine and SnCl2 in CH2Cl2

The Q-band position of tin-centered 5, 9, 14, 18, 23, 27, 32, 36-octabutoxy 2, 3-phthalocyanine(SnNc(OBu)8) exhibits dramatic red-shift as mixed with SnCl2 in CH2Cl2.     

Mechanism of UV photoreactivity of alkylsiloxane self-assembled monolayers

A molecular level understanding of the photoreactivity of self-assembled monolayers (SAMs) becomes increasingly important as the spatial resolution starts to be limited by the size of the resist and the spatial extent of the photochemical reactions in photoresist micropatterning. To this end, a number of surface characterization techniques were combined to understand the reactive agents, reactive sites, kinetics, and reaction pathways in the UV photoreactivity of octadecylsiloxane (ODS) SAMs. Quantitative analysis of our results provides evidence that ground state atomic oxygen is the primary reactive agent for the UV degradation of ODS SAMs. UV degradation, which follows zero-order kinetics, results in the scission of alkyl chains instead of the siloxane headgroups. Our results suggest that the top of the ODS SAMs is the preferential reactive site. Using a novel, highly surface sensitive technique, fluorescence labeling of surface species, we identified the presence of submonolayer quantities chemical functional groups formed by the UV degradation. These groups are intermediates in a proposed mechanism based on hydrogen abstraction.     

A gravimetric method for the determination of oxygen in uranium oxides and ternary uranium oxides by addition of alkaline earth compounds

A simple gravimetric determination of oxygen in uranium oxides and ternary uranium oxides is described. In alkaline earth uranates which are formed by heating in air at 800–1100°C, uranium is in the hexavalent state over certain continuous ranges of alkaline earth-to-uranium ratios. Thus, if an alkaline earth uranate or a compound containing an alkaline earth element, e.g. MgO, is mixed with the oxide sample and heated in air under suitable conditions, oxygen can be determined from the weight change before and after the reaction. The standard deviation of the O:U ratio for a UO_2+x test sample is ±0.0008–0.001, if a correction is applied for atmospheric moisture absorbed during mixing.     

Tertiary amine-mediated synthesis of microporous carbon membranes

Microporous carbon membranes were prepared on an -alumina support by a pyrolysis of cationic tertiary amine/anionic polymer composites. The precursor solutions contain a thermosetting resorcinol/formaldehyde (RF) polymer and a cationic tertiary amine. Three types of cationic tertiary amines with different chain lengths were used, such as tetramethlammonium bromide (TMAB), tetrapropylammonium bromide (TPAB) and cetyltrimethylammonium bromide (CTAB). A porous structure was produced by a decomposition of the amine and the resulting pores assisted the further gasification of the RF polymer at high temperature. The carbon/alumina membranes have thin and continuous carbon top layers with a thickness of 1 μm. Gas permeation tests were performed using single gases of CO₂, O₂, N₂, CF₄, n-C₄H₁₀ and i-C₄H₁₀, as well as binary mixtures of CH₄/n-C₄H₁₀ and N₂/CF₄ at different temperatures between 23 and 150 °C. The carbon membrane prepared using TMAB showed separation factors higher than 650 for the CH₄/n-C₄H₁₀ mixtures and higher than 8100 for the N₂/CF₄ mixture. From the permeation of pure gases with different molecular sizes, the pore sizes of the carbon membrane prepared using TMAB, TPAB and CTAB are estimated to be 4.0, 5.0 and larger than 5.5 Å, respectively, indicating that the micropore size of the carbon membranes is controllable by using different amines.     

Swelling kinetics and release characteristic of crosslinked chitosan: Polyether polymer network (semi-IPN) hydrogels

The aqueous swelling kinetics of a series of crosslinked chitosan (cr-CS) with glutaraldehyde (GA) interpenetrating polyether hydrogels have been studied as functions of pH, the N-deacetylation degree of chitosan, the amount of crosslinking agent, the electrolyte composition in solution, temperature, and gel composition. Based on these results, the swelling mechanism of the hydrogels was discussed. The release profiles of chlorhexidini acetas from the semi-IPN were also investigated. © 1994 John Wiley & Sons, Inc.     

富勒烯化聚环氧丙基咔唑的合成与表征

通过Ｆｒｉｅｄｅｌ－Ｃｒｒａｆｔｓ反应制备了富勒烯化的聚环氧丙基咔唑，聚合物中Ｃ６０的含量最高可达７．６ｗｔ％。通过凝胶渗透色谱法测定了聚合物分子量，并采用＾上Ｈ和＾１３Ｃ－ＮＭＲ，ＩＲ，热分析及光谱等手段对其结构进行了分析与表征。     

A comparative study on photo-induced electron transfer from fluorescein to anthraquinone and injection into colloidal TiO2

A dyad-anthraquinone-methyl ester of fluorescein-and its model compound-butyl ester-were synthesized. The effects of photo-induced electron transfer from fluorescein to an organic anthraquinone acceptor and injection into inorganic colloidal TiO(2) were studied respectively. It is found that the photo-induced electron transferring to an organic acceptor is much faster than injecting into inorganic colloidal particles when fluorescein was excited by visible light. While inorganic colloidal TiO(2) was excited by UV, the electron of fluorescein will inject into TiO(2).