PHOTOOXYGENATION OF CAFFEINE SENSITIZED BY HYPOCRELLIN B

The photooxygenation of caffeine sensitized by Hypocrellin B in alcohol solvents hasbeen investigated in this paper. The products have been isolated and identified. The mainproduct is 8--alkoxyl substituted caffeine derivatives. Deuterium. oxygen partial pressure andNaN_3-quenching experiments indicate that the reaction proceeds on singlet oxygen mechanism.     

PHOTOSENSITIZATION OF METHYL LINOLEATE OXIDATION BY TRYPTOPHAN IN PEPTIDES

The ability of tryptophan in peptides to photosensitize the oxidation of methyl linoleate (ML) was evaluated. Purified ML was irradiated (λ > 270 nm) alone or in the presence of a tryptophan-containing peptide in ethanol solution. Oxidation was monitored by measuring the dienc hydroperoxides formed from ML by high performance liquid chromatography. N-acetylphenylalanyltryptophan (NAPT) and N-acetyltryptophan were about 2-fold more effective as photosensitizers than leucyltryptophan and tryptophylleucine. N-acetylphenylalanyltryptophan photolyzed in ethanol to form multiple photoproducts including N-formylkynurenine-type compounds. However, the NAPT photoproducts did not photosensitize the oxidation of ML and N-formylkynurenine was about 8% as effective as NAPT. Sodium azide partially quenched the photooxidation sensitized by NAPT.     

苯乙烯与甲基丙烯酸甲酯在聚乙二醇水溶液中无皂乳液共聚的粒径变化

利用高倍光学显微镜、库尔特粒径测试仪、TEM及zeta电位跟踪观测了苯乙烯(St)与甲基丙烯酸甲酯(MMA)在聚乙二醇(PEG)水溶液无皂乳液共聚过程中的粒径、粒径分布以及zeta电位变化.聚合物粒径会经历由小到大(某些粒径甚至超过1000μm,分布在0.04～2000μm的极宽范围内),再由大变小(形成的数均分布在0.04～0.18μm)过程,且粒径分布也由宽变窄,最终粒径数均分布集中在0.04～0.18μm窄范围内.结合聚合转化率数据,根据PEG水溶液中进行的St/MMA无皂乳液共聚粒径变化过程,以及zeta电位在聚合过程中异于普通无皂乳液的现象,认为该体系在反应初期形成的粒子会形成粒子堆,并随着聚合反应的继续,带有离子片段的自由基链段不断扩散进入粒子堆表面的小粒子,使其zeta电位不断增强,最终脱离粒子堆.提出了PEG水溶液中St/MMA无皂乳液共聚聚并脱析成核机理.     

DIRECT AND SENSITIZED PHOTOOXIDATION OF CYANINE DYES

Abstract —Direct photooxidation of cyanine dyes was found to be markedly enhanced by formation of hypsochromically shifted (H) aggregates. Singlet oxygen was found to attack many cyanines possessing low oxidation potentials with rate constants in excess of 10⁸ t mol^-1 s^-1. Singlet oxygen attack on 3,3'-diethyl-8,10-dimethylthiacarbocyanine yields carbonyl products consistent with 1,2 addition to the 2,8 bond of the methine chain.     

温度对丙烯腈-丙烯酸甲酯水相沉淀共聚合竞聚率的影响

应用气相色谱法研究了温度对丙烯腈-丙烯酸甲酯水相沉淀共聚合竞聚率的影响,测得30℃时r_1=0.96,r_2=1.18;40℃时r_1=0.83,r_2=1.17;50℃时r_1=0.70,r_2=1.17;60℃时r_1=0.68,r_2=1.10,竞聚串与反应温度的关系为:1nr_1=-4.043+1207/T,1nr_2=-0.01360+51.68/T。发现共聚物沉淀粒子的表面吸附作用对该共聚体系竞聚率的温度依赖性有很大影响。     

AN ULTRASTRUCTURAL COMPARATIVE EVALUATION OF TUMORS PHOTOSENSITIZED BY PORPHYRINS ADMINISTERED IN AQUEOUS SOLUTION, BOUND TO LIPOSOMES OR TO LIPOPROTEINS

Abstract— Balb/c mice bearing a transplantedMS–2 fibrosarcoma have been injected with 2 mg kg^-1 hematoporphyrin either dissolved in phosphate-buffered saline (Hp-aq), or incorporated into unilamellar liposomes of dipalmitoyl-phosphatidylcholine (Hp-lip), or precomplexed with low density lipoproteins (Hp-LDL). At 24 h after injection, the mice received 150 J cm^-2 of600–680 nm light irradiation. Electron microscopic studies performed on tumor tissues taken from mice sacrificed at different times after the phototreatment showed that, in the presence of Hp-aq. tumor necrosis is largely the consequence of vascular damage. On the other hand, in the presence of Hp-lip and Hp-LDL, the response of the tumor to the phototreatment occurs at a faster rate and is mainly determined by direct damage of neoplastic cells. These findings are correlated with the different distribution of the various hematoporphyrin forms (Hp-aq, Hp-lip, Hp-LDL) among the serum proteins and the modalities of hematoporphyrin delivery to tissues by the possible carriers.     

SENSITIZED PHOTOOXYGENATION REACTIONS AND THE ROLE OF SINGLET OXYGEN†,‡

Abstract— In this paper we discuss various theoretical and experimental aspects of the role of singlet oxygen in sensitized photooxygenation reactions. New spectroscopic observations on the photosensitized production of singlet oxygen molecules are presented. The various factors which control the generation and reactions of singlet oxygen molecules are considered in detail. A relatively simple theoretical procedure is developed to predict the relative reactivities of ¹σ, ¹δ and ³σ oxygen toward various organic acceptors, and is used to discuss the chemical and photochemical properties of some of the oxygenation products. Finally, the properties of dioxetanes are examined in connection with the role which they may play in chemi- and bioluminescence. While we have said rather little about photodynamic reactions per se , the results presented in this paper strongly support the suggestion that many of the observed photodynamic effects could be due to reactions of singlet oxygen. Clearly a careful reexamination of various photodynamic effects at the molecular level to establish whether or not reactions of singlet oxygen are involved is now in order.     

烷基苄基铵对芘的荧光猝灭行为研究

广义的荧光猝灭系指所有能使荧光强度降低的物理和化学过程,但通常涉及的主要有动态猝灭和静态猝灭,二者均遵从Stern-Volmer方程,但由于猝灭作用本质不同,它们在荧光寿命变化、温度效应及吸收光谱等方面表现出差异可资区别.本文通过稳态荧光强度变化和荧光衰减速率的比较研究了具有不同烷基链长的十四烷基苄基二甲基氯化铵(Zeph)和苄基三甲基溴化铵(TMBA)对芘的荧光猝灭,并基于电导实验结果以及猝灭剂全反式构象从理论上计算了Zeph和TMBA的猝灭速率常数,讨论了荧光猝灭的性质和长链分子的构型。     

SELECTIVE PHOTOOXIDATION OF THIOLS SENSITIZED BY AQUEOUS SUSPENSIONS OF CADMIUM SULFIDE

-Finely powdered cadmium sulfide in aqueous, air-saturated, phosphate buffered suspension sensitizes the photooxidation of cysteine to cystine with good efficiency; several additional thiols and inorganic sulfides are also photooxidized. The other amino acids (histidine, methionine, tryptophan, tyrosine) known to be rapidly photooxidized with typical organic photosensitizers are photooxidized only very slowly. The quantum yield of oxygen uptake during cysteine photooxidation is pH dependent with a maximum (0.021) at pH 9.5; the yield is not increased in D₂O and is not decreased appreciably by sodium azide, suggesting that singlet oxygen is not involved in the photooxidation process. The slow rate of photooxidation of histidine, which is known to react efficiently with singlet oxygen, also suggests that little if any singlet oxygen is produced by illuminated cadmium sulfide. Superoxide dismutase inhibits the yield of cysteine photooxidation to a maximum of approximately 50%, suggesting the partial involvement of superoxide in the reaction mechanism. The quantum yields of the photooxidation of cysteine, ethylenediaminetetraacetate and inorganic sulfides decrease as the wavelength of the exciting light is increased. Yeast alcohol dehydrogenase, a sulfhydryl enzyme, is inactivated by photodynamic treatment with cadmium sulfide; lysozyme, which has no free sulfhydryl groups, is not.     

醇水介质中漆酶催化氧化漆酚及其类似物

本文作者在醇水介质中对漆酚及其类似物的酶催化氧化反应进行了研究。探讨了混合溶剂中漆酶的行为。结果发现邻苯二酚被烷基取代后更有利于漆酶的催化氧化。反应可能经过两个步骤,先是底物氧化生成黄色苯醌类物质,然后醌类中间物偶联形成多聚酚。     

LUMINESCENCE AND PHOTOCHEMISTRY OF 4-THIOURIDINE IN AQUEOUS SOLUTION

Abstract— In bidistilled water, 4-thiouridine (4TU) exhibits a weak unusual luminescence, the quantum yield of which is 3 × 10^-4 at 25°C. The excitation spectrum corresponds well to the 4TU absorption spectrum. The emission lies at longer wavelengths (Λ_max 550 nm) than the 4TU phosphorescence observed at 77 K (Λ_max, 470–480 nm). From the emission signal obtained after an excitation flash of 3 ns half-width, an "apparent" rate constant for the radiative deactivation process, shorter than 5 × 10⁶ s, can be inferred. The 300 K emission is efficiently quenched by halides and by oxygen: quenching involves a long-lived intermediate (⋍ 200 ns).
Clearly the emissive state X is populated through the S₀-S₁ electronic transition π→π* of 4TU. The nature of X cannot be unambiguously determined: it cannot be an excimer but can be either the 4TU triplet state or another chemical state distinct from the 4TU excited singlet or triplet states.
An interesting finding is that the 300 K emission and the ability of 4TU to photoreact are related: they are quenched with the same efficiency by halide anions. This indicates that quenching occurs at the same long-lived intermediate species , which is either a precursor of the emitter or the emitter itself.     

乙烯砜型染料与丙烯腈的水相沉淀聚合

乙烯砜型染料与丙烯腈的水相沉淀聚合吴致宁，张雪松，杨锦宗大连理工大学精细化工系，大连，１１６０１２）关键词高分子染料、沉淀共聚合、乙烯砜型染料、丙烯腈近年来，随着人们对功能材料具有高附加值的认识的不断深人，特别是伴随各类功能性染料结构的开发，高分子染...     

乙烯砜型染料与丙烯腈的水相沉淀聚合

he copolymerization of vinyl sulphone dyes with acrylonitrile were carried outin HIO media. The effects of the increase in dye concentration on the conversionof copolymerization molecular weight of copolymer, and the content of dyechromophores combined in the copolymer were studied. The eghaneemellt on thetermination of macromolecular radicals by added dyes was discussed.     

ADSORPTION OF 4-METHYLANILINE IN AQUEOUS SOLUTION BY BENZOYL-CONTAINING POLYMERIC ADSORBENTS

New polymeric adsorbents (ZH-02, ZH-03) containing benzoyl group for adsorbing and removing 4-methylaniline from its aqueous solutions were prepared. Studies on the isotherms and the comparison of desorption conditions evidenced through the adsorption of 4-methylaniline in water onto ZH-02 and ZH-03, namely that there are chemisorption‘s transitions at a proper higher temperature. Mini-colunm adsorption studies of 4-methylaniline on XAD-4, ZH-02 and ZH-03 at 288 K show that the breakthrough capacities are 2.39, 2.99 and 3.19 mmol/g and the total capacities are 3.45, 3.92 and 4.35 mmol/g, respectively.     

MMA—St无皂乳液聚合成核机理探讨

讨论了MMA-St无皂乳液聚合,当[KPS]=2.77×10~(-3)mol/L,[MMA]0.51mol/L,[St]=0.49mol/L,70℃反应5.0小时,能得到较高的聚合转化率,较小的胶乳粒径和较大的粒子浓度,并对不同反应时期聚合物的分子量及其分布进行了测定,认为该无皂乳液聚合体系为均相沉淀成核机理。当转化率大于30.9％时,胶乳粒的凝聚程度大于胶乳粒的生成速度。KPS分解产生的自由基起到了稳定乳液的作用。     

FLUORESCENCE AND PHOTOCHEMISTRY OF OLIGOCYTIDYLIC AND POLYCYTIDYLIC ACIDS IN AQUEOUS SOLUTION

Abstract —In addition to the monomer-like fluorescence, a long-wavelength emission (Λ^max_em= 410 nm) has been detected in the dinucleoside 5'-5' pyrophosphate (CppC) at room temperature. This emission looks very similar to that previously reported for the acidic forms of Poly C (Poly C. Poly C⁺ and Poly I. Poly C. Poly C⁺). Only the monomer-like emission (Λ^max_em= 330 nm) can be detected in neutral Poly C, acidic CppC, and the neutral or protonated forms of the dinucleoside phosphate CpC.A correlation between the room temperature fluorescence of oligo and polycytidylic acids and their photochemical behaviour is found. Irradiation of all the polymeric samples at both neutral and acid pH results in the formation of minor photoproducts. They have been characterized by their absorbance (in the range 300–400 nm) and their fluorescence spectra. The same product is obtained in all cases where the monomer-like fluorescence only is detected. Distinct products are formed in neutral CppC and in the acidic Poly C forms.
The results are discussed with respect to the conformation of the oligo and polycytidylic acids and possible relationships between the 410–420 nm emission and adduct formation. An excimer is proposed as a common, intermediate excited state in both radiative deactivation and adduct formation in neutral CppC and the acidic Poly C forms.     

二阶梯度升温热解吸法测定空气中的微量丙烯腈和乙腈

采用气体采样泵将空气样品的丙烯腈和乙腈吸附到吸附管中,用二阶梯度升温将吸附管中的被测物质解吸到冷阱中,再快速对冷阱升温,将冷阱中的被测物质解吸进入色谱柱进行分离,用气相色谱氢火焰检测器检测空气中的微量丙烯腈和乙腈。丙烯腈、乙腈的色谱峰面积与吸附质量的线性相关系数均大于0.995。该法对实际空气样品中丙烯腈的检出限为5μg/m3,乙腈的检出限为10μg/m3,加标回收率均大于90%。     

离子色谱法测定乙二胺水溶液中的SO32-、SO42-

用离子色谱法测定5％乙二胺水溶液中的SO3^2-、SO4^2-。选用IonPac柱，以3mmol/L AS11分离碳酸钠－10％甲醇水溶液作为淋洗液，20min内便可完成测定。SO3^2-和SO4^2-的回收率分别为97.6%-101.6%和99.2%-101.0%，相对标准偏差分别为1．31％和1．42％。     

pH DEPENDENCE OF SENSITIZED PHOTOOXIDATION IN MICELLAR ANIONIC AND CATIONIC SURFACTANTS, USING THIAZINES DYES

Abstract— Our study of the kinetics of sensitized photooxidation, as a function of pH in anionic micellar systems using cationic dyes as sensitizers, shows that adsorption of the dye slows the protonation step of his triplet state. This observation has important implicaticins in interpretation of results in the so-called photodynamic effect in biological systems: using cationic dyes as sensitizers the rate of photooxidation for the same pH is different depending whether or not the medium allows adsorption of the dye.