维生素E对萼花臂尾轮虫繁殖的影响

15℃下 ,添加 Ve浓度为 2 0～ 80 ng/ m l时 ,种群密度与培养时间呈显著相关 ,其中 2 0 ng/ ml和 4 0 ng/ ml组最大种群密度分别为 76 .4 0 ind/ ml和 6 5 .2 0 ind/ ml,显著高于对照组 (最大密度 12 .0 0 ind/ ml)。最大混交雌体百分率低于 10 % ,对照组最大混交雌体比率为 4 0 %。轮虫卵雌比有不同程度的提高 ,但维生素浓度为 10 0 ng/ ml时 ,对种群增长不利 ;2 5℃下 ,对照组和各添加组最大密度依次为

团头鲂的胚胎及成体组织中八种同工酶系统的研究

用垂直的淀粉凝胶电泳方法分析了胚胎发育阶段(0—105小时)和成体6种组织中的乳酸脱氢酶(LDH)、苹果酸脱氢酶(MDH)、谷氨酸脱氢酶(GDH)、葡萄糖-6-磷酸脱氢酶(G6PD)、醇脱氢酶(ADH)、异柠檬酸脱氢酶(IDH)、酯酶(EST)和碱性磷酸酶(AKP)等8种同工酶系统的酶带。共约有23个基因座位在其胚胎发育期和成体组织中表达。所分析的大多数同工酶在团头鲂个体发生过程中表达的情况大致可分为3种类型:①胚胎发育期间持续存在的同工酶类,它们在成体组织中无特异性分布;②到胚胎发育后期才开始表达的同工

Mouse Toxicity of Anabaena flos-aquae from Lake Dianchi, China

Some species of the genera Anabaena can produce various kinds of cyanotoxins, which may pose risks to environment and human health. Anabaena has frequently been observed in eutrophic freshwater of China in recent years, but its toxicity has been reported only in a few studies. In the present study, the toxicity of an Anabaena flos-aquae strain isolated from Lake Dianchi was investigated. Acute toxicity testing was performed by mouse bioassay using crude extracts from the lyophilized cultures. The mice exposed to crude extracts showed visible symptoms of toxicity and died within 10-24 h of the injection. Serum biochemical parameters were evaluated by the use of commercial diagnostic kits. Significant alterations were found in the serum biochemical parameters: alkaline phosphatase (AKP), gamma-glutamyl transpepticlase (gamma-GT), aspartate amino transferase (AST), alanine amino transferase (ALT), AST/ALT ratio, total protein content, albumin content, albumin/globulin (A/G) ratio, blood urea nitrogen (BUN), serum creatinine (Ssr), and total antioxidative capacity (T-AOC). Histopathological observations were carried out with hematoxylin and eosin (HE) stain under light microscope. Severe lesions were seen in the livers, kidneys, and lungs of the mice injected with crude extracts. The alterations of biochemical parameters were in a dose-dependent manner, and the severities of histological lesions were in the same manner. Based on biochemical and histological studies, this research firstly shows the presence of toxin-producing Anabaena species in Lake Dianchi and the toxic effects of its crude extracts on mammals. (C) 2008 Wiley Periodicals, Inc. Environ Toxicol 24: 10-18, 2009.

Effects of solar UV radiation on morphology and photosynthesis of filamentous cyanobacterium Arthrospira platensis

To study the impact of solar UV radiation (UVR) (280 to 400 nm) on the filamentous cyanobacterium Arthrospira (Spirulina) platensis, we examined the morphological changes and photosynthetic performance using an indoor-grown strain (which had not been exposed to sunlight for decades) and an outdoor-grown strain (which had been grown under sunlight for decades) while they were cultured with three solar radiation treatments: PAB (photosynthetically active radiation [PAR] plus UVR; 280 to 700 nm), PA (PAR plus UV-A; 320 to 700 nm), and P (PAR only; 400 to 700 nm). Solar UVR broke the spiral filaments of A. platensis exposed to full solar radiation in short-term low-cell-density cultures. This breakage was observed after 2 h for the indoor strain but after 4 to 6 h for the outdoor strain. Filament breakage also occurred in the cultures exposed to PAR alone; however, the extent of breakage was less than that observed for filaments exposed to full solar radiation. The spiral filaments broke and compressed when high-cell-density cultures were exposed to full solar radiation during long-term experiments. When UV-B was screened off, the filaments initially broke, but they elongated and became loosely arranged later (i.e., there were fewer spirals per unit of filament length). When UVR was filtered out, the spiral structure hardly broke or became looser. Photosynthetic 0, evolution in the presence of UVR was significantly suppressed in the indoor strain compared to the outdoor strain. UVR-induced inhibition increased with exposure time, and it was significantly lower in the outdoor strain. The concentration of UV-absorbing compounds was low in both strains, and there was no significant change in the amount regardless of the radiation treatment, suggesting that these compounds were not effectively used as protection against solar UVR. Self-shading, on the other hand, produced by compression of the spirals over adaptive time scales, seems to play an important role in protecting this species against deleterious UVR. Our findings suggest that the increase in UV-B irradiance due to ozone depletion not only might affect photosynthesis but also might alter the morphological development of filamentous cyanobacteria during acclimation or over adaptive time scales.

Experimental Demonstration on Structure-Parameter Dependence of Photonic Crystal Optical Spectrum

We present fabrication and experimental measurement of a series of photonic crystal waveguides and coupled structure of PC waveguide and PC micro-cavity. The complete devices consist of an injector taper down from 3 mu m into a triangular-lattice air-holes single-line-defect waveguide. We fabricated these devices on a silicon-on-insulator substrate and characterized them using tunable laser source. We've obtained high-efficiency light propagation and broad flat spectrum response of photonic-crystal waveguides. A sharp attenuation at photonic crystal waveguide mode edge was observed for most structures. The edge of guided band is shifted about 31 nm with the 10 nm increase of lattice constant. Mode resonance was observed in coupled structure. Our experimental results indicate that the optical spectra of photonic crystal are very sensitive to structure parameters.

Experimental Demonstration on Structure-Parameter Dependence of Photonic Crystal Optical Spectrum

We present fabrication and experimental measurement of a series of photonic crystal waveguides and coupled structure of PC waveguide and PC micro-cavity. The complete devices consist of an injector taper down from 3 mu m into a triangular-lattice air-holes single-line-defect waveguide. We fabricated these devices on a silicon-on-insulator substrate and characterized them using tunable laser source. We've obtained high-efficiency light propagation and broad flat spectrum response of photonic-crystal waveguides. A sharp attenuation at photonic crystal waveguide mode edge was observed for most structures. The edge of guided band is shifted about 31 nm with the 10 nm increase of lattice constant. Mode resonance was observed in coupled structure. Our experimental results indicate that the optical spectra of photonic crystal are very sensitive to structure parameters.

黄土旱塬不同水分管理模式对旱作春玉米土壤温度的影响

基于春玉米生长季土壤温度动态观测资料,研究黄土高原南部旱作区不同水分管理模式对春玉米(Zeamays)农田土壤温度动态变化和玉米生育期土壤积温(>10℃)的影响,其结果对理解不同水分管理模式对玉米生长影响具有一定参考价值。【方法】以沈单10为供试作物品种,水分管理模式2007年采用补充灌溉、雨养和地膜覆盖3种处理。在2007年基础上,2008年增加秸秆覆盖,试验采用完全方案,于2007年和2008年连续进行2年田间试验。【结果】地膜覆盖具有明显的增温效应,而秸秆覆盖具有明显降温效应;玉米不同生育阶段>10℃土壤积温,以出苗阶段(PT-VE)最低,生殖生长阶段(R1-R6)次之,营养生长阶段(VE-R1)最高。不同水分管理模式对不同生育期的土壤积温影响不同:地膜覆盖在PT-VE阶段较低,补充灌溉在VE-R1阶段较低,雨养处理在R1-R6阶段较低。地膜覆盖条件下土壤温度对大气温度变化的响应更为敏感,与大气温度变化最为紧密;而秸秆覆盖土壤温度对大气温度变化的反应最迟钝。补充灌溉和地膜覆盖处理籽粒产量显著高于雨养处理(P<0.05),与雨养相比,2007和2008年补充灌溉分别增产30.0%和25.7%,地膜...

（一）聚丁二烯橡胶的高聚物-溶剂相互作用参数从和有效网链密度的测定（二）顺丁橡胶在几种溶剂中的特性粘数-分子量关系式和无扰分子尺寸的估算

表征硫化橡胶弹性体网络的主要结构参数是有效网链密度橡胶弹性体的许多重要力学性能，例如：300%定伸强度、抗张强度、伸长率、抗撕裂、弹性、硬度、静态压缩模量和动态模量等都是和有效网链密度紧密相关的。Flory用平衡溶胀法测定有效网链密度的方程是：Ve = -1/(V_s)·(l_n(1-υ_r) + υ_r + μυ_r~2)/(υ_r~(1/3)-2υ_r/f)式中的Ve是有效网链密度（用单位体积橡胶的有效网链克分子数来表示），υ_r是溶胀网络中橡胶的体积分数，υ_s是溶剂的克分子体积，f是交联点的官能度（f = 4），μ是高聚物溶剂相互作用参数。首先要确定μ才能够用上式来测定硫化胶的有效网链密度以表征硫化程度。实验事实和Flory等人的理论工作表明：μ不是常数，是υ_r的函数。高顺式聚丁二烯橡胶已生产多年，但迄今未有关于高顺式聚丁二烯橡胶在不同溶剂中的μ和υ_r间的函数关系的报导。在实际应用中，人们常常用υ_r值的大小来近似表征硫化程度。但由上式可知：μ和υ_r不成正比关系。因此，必须求得μ值，才能得到Ve值，以正确表征硫化程度，对实际生产起指导作用。本工作采用溶胀-拉伸方法不渗透压，光散射等方法测定顺丁橡胶和溶剂甲苯、苯、正-庚烷的相互作用参数μ，得到了μ和υ_r的线性函数（见附表），μ = μ_o + βυ_r。μ_o是当υ_r趋向于零时的μ值，β是一个常数。溶胀拉伸法外推得到的μ_o值和用渗透压及光散射法得到的μ_o值么接近，为实验的可靠性提供了依据。力学方法和物理化学方法同时测得相近的结果，有文献报导的不多。用溶胀-拉伸法求橡胶-溶剂的相互作用参数μ，由于样品的制作和实验技术上的困难内尚未见报导。国外Kraus和V. Zanboni等人用天然、丁苯、乙丙、丁腈等纯胶硫化胶（未加碳黑的硫化胶）进行溶胀-拉伸实验，测定μ和U_r的函数关系。然后用来计算碳黑硫化胶的μ和Ve。本工作表明：对于同一橡胶-溶剂体系来说，纯胶硫化胶和碳黑硫化胶的μ和υ_r的函数关系并不一样，在相同υ_r时，二者Ve相差2.5-5%，υ_r值越大，Ve相差越大。因此用纯胶硫化胶的μ和υ_r的函数来计算碳黑硫化胶的有效网链密度是不适当的。本工作还用渗透压法测定了1，2-聚丁二烯（1，2-含量分别为90%和60%）及合成异戊橡胶和溶剂甲苯的相互作用参数μ_o。结果表明：合成异戊橡胶和天然橡胶有相同的μ_o值。这说明μ_o值只和化学结构有关，与样品的来源无关。两种1，2-聚丁二烯橡胶和顺丁橡胶也有相接近的μ_o值。其原因是因为三者有基本相同的内聚能密度，则它们在同一种溶剂中所受到的作用力应当相等的缘故。最后，本工作还研究了顺丁橡胶的有效网链密度对300%定伸强度、抗张强度、抗撕裂、伸长率、弹性、硬度、静态压缩模量和动态模量等力学性能的影响。结果表明：有效网链密度Ve和300%定伸强度成直线函数关系：M_(300%) = 17 + 3.61 * 10~5 * Ve（公斤/厘米）。这就为测定硫化胶的有效网链密度提供了另一条途径，因为300%定伸强度是表征硫化胶的一个重要参数，实验简单易行，知道了M_(300%)就可以利用上式估算Ve。本工作发现有效网链密度在2.00～3.10 * 10~(-4)摩尔/厘米~3的范围内，则可望达到优秀的抗张强度和抗撕裂性能，对实际生产的工艺控制有一定现实意义。本工作以稀土催化体系合成的顺丁橡胶（顺1，4-97%、反1，4-2.5%、1.2-0.5%）作为研究对象，订定了顺丁橡胶在溶剂四氢呋喃、甲苯、甲基环乙烷、正-庚烷和丁酮与正-庚烷混合溶剂（体积比为2:1）等中的特性粘数分子量关系式：用Kurata-Stockmayer(KS)方程、Stockmayer-Fixman(SF)方程和Tnagaki-Ptitsyn(IP)方程估算了顺丁橡胶的无扰分子尺寸。顺丁橡胶在溶剂四氢呋喃中的特性粘数-分子量关系式为[η]_(THF)~30 ℃= 0.0246 * M~(0.732)该关系式的获得为采用自记GPC测定和计算顺丁橡胶样品的(M-bar)_w、(M-bar)_n、(M-bar)_w/(M-bar)_x和[η]等重要分子参数提供了方便。因顺丁橡胶在四氢呋喃中的特性粘数-分子量关系式文献至今未见报导。顺丁橡胶在甲苯、甲基环乙烷、正-庚烷和丁酮与正-庚烷混合溶剂中的特性粘数-分子量关系式如下：[η]_(甲苯)~(30 ℃) = 0.0264 * M~(0.719) [η]_(甲基/环已烷)~(30 ℃) = 0.0293 * M~(0.698) [η]_(正-庚烷)~(30 ℃) = 0.1181 * M~(0.547) [η]_(丁酮+正-庚烷)~(30 ℃) = 0.1800 * M~(0.500)发现酮与正-庚烷的混合溶剂（体积比为2:1）在30 ℃时是顺丁橡胶的Θ溶剂。高聚物的无扰分子尺寸，是反映大分子近程相互作用的重要参数，由此可得到有关链结构的重要情报。本工作通过测定已知分子量的样品在四氢呋喃、甲苯、甲基环已烷等良溶剂中的特性粘数，采用KS、SF和IP方程去估算顺丁橡胶的无扰分子尺寸，同时测定了顺丁橡胶在其Θ条件下（丁酮与正-庚烷混合溶剂，体积比2:1，温度30 ℃）的无扰分子尺寸，以此进行对比。用KS方程估算的K_θ = 0.183(ml/g), <γ_o~2>~(1/2)/M~(1/2) = 0.0901(nm)用SF方程估算的K_θ = 0.183和0.200(ml/g), <γ_o~2>~(1/2)/M~(1/2) = 0.0901和0.0928(nm)用IP方程估算的K_θ = 0.192(ml/g), <γ_o~2>~(1/2)/M~(1/2) = 0.0915(nm)用Θ溶剂测定的K_θ= 0.180(ml/g), <γ_o~2>~(1/2)/M~(1/2) = 0.0896(nm)由此可见，用不同方法得到的结果均较接近。

无规支化高聚物溶液标度规则的研究

研究分化结构对标度律的影响，具有重要的理论意义。1. 支化物的合成与表征 通过苯乙烯（ST）和少量二乙烯基本（DVB）共聚，制得了几个四官能度分化聚苯乙烯（BpS）样品。利用GpC数据和[η]值，用电子计算机试误法拟合粘度曲线，确定了四官能度支化聚苯乙烯的分子量和支化参数。2. 只通过线型和无规分化聚苯乙烯的lyM-Ve曲线的斜率求得了回转半径与聚合度关系R_b ～ N~(ν_b)中的标度指数ν_b = 0.459，与计算和结果相符合。（本实验中得到ν_t = 0.553）。3. 用光子相关光谱研究了支化结构对扩散解为的影响。无规支化聚苯乙烯分子在环已烷中扩散（稀溶液范围）与浓度和温度有关，发现支化对浓度系数kd有影响，kd = 0时的温度Tc（这一温度是高分子链从θ条件下的无扰状态向良溶剂中链完全伸展状态过渡的临界温度）由于分子的支化而升高，扩散系数具有处复的浓度依赖关系（55 ℃时B4-2的kd = 0）。4. 支化对细结的影响 用粘度法测定了LpS和BpS样品在25 ℃THF中的临界结浓度C_E~*，在我们测定的分子量范围内，无论LpS还是BpS的临界细结浓度C_E~*都与C_E~* ～ N~(1-3ν)标度关系存在偏离，这是由于未考虑排除体积效应（与分子量有关）造成的。从上看出，支化分子的标度规则与线型分子的存在明显差别，而且在不同的浓度原，长支链的存在（结构因素）和由于支化使分子尺寸变小对溶液性质具有不同的影响。

耐酸产甲烷菌的分离及其复合菌剂的研究

本文从成都龙泉垃圾填埋场和宜宾造纸厂分离到耐酸性能优良的高温产甲烷菌RY3和中温产甲烷菌SH4，并将其与实验室现有的利用不同底物的产甲烷菌配伍组合成了复合菌剂。采用活性污泥作为固体附着物，研制出了固体产甲烷菌复合菌剂。 菌株RY3的pH耐受范围为5.5～10.5，最适生长pH 6.0～8.0。菌株RY3为革兰氏阳性，长杆状，多数单生，不运动；菌落浅黄色，形状近圆形；利用H2+CO2或甲酸盐作为唯一碳源生长，不利用乙酸盐，对氯霉素非常敏感。该菌最适生长温度为55℃～65℃，最适NaCl浓度为0～2%。根据形态和生理生化特性及16S rDNA序列分析将其初步定为热自养甲烷热杆菌（Methanothermobacter thermautotrophicus）。添加RY3菌液与仅添加厌氧污泥作为接种物相比一周内可使达到最大产甲烷速率所需时间缩短三分之二，甲烷总产量提高约1.8倍。菌株SH4的生长pH范围5.5～9.5，其对酸碱具有良好的适应性，培养3天后，在初始pH值为6.0～8.0的培养基中甲烷产量相差不大，且基本达到最大产量。SH4革兰氏染色阳性，短杆状，多数单生，不运动；菌落近圆形，微黄；利用H2+CO2或甲酸盐作为唯一碳源生长，不利用乙酸盐，对氯霉素非常敏感。SH4最适生长pH 为7.0，最适生长温度为35℃，最适NaCl浓度为0～1.5%。实验表明，添加SH4菌液与仅添加厌氧污泥作为接种物相比可使产甲烷启动时间缩短三分之一，甲烷总产量亦有大幅提高。从形态和生理生化特征以及16S rDNA序列分析表明SH4为嗜树木甲烷短杆菌（Methanobrevibacter arboriphilus）。 以活性污泥为附着物，与培养基和菌种经搅拌后厌氧发酵可得产甲烷菌固体复合菌剂。固体复合菌剂的pH耐受范围为5.5～9.5，温度耐受范围为15℃～65℃，表明其对环境的适应性较强。以猪粪为底物进行厌氧发酵，接种复合菌剂进行试验，以接种实验室长期富集的产甲烷厌氧污泥作为对照，在20℃时，发酵甲烷浓度与对照基本一致，但每日产气量优于对照，第15天时接种复合菌剂的发酵瓶每日产气量是对照的1.59倍；50℃时达到最大甲烷含量所需时间比对照缩短三分之二，三周内总产气量约为对照的2.7倍，甲烷总产量约为2.8倍。以不加接种物为对照，接种复合菌剂20℃时发酵甲烷含量达到50%约需2周，对照2周内甲烷含量最高仅为4.3%；50℃时接种复合菌剂发酵仅需约1周甲烷含量便可达50%，对照则至少需要2周。 In this paper, high-temperature Methanogen RY3 and middle-temperature SH4 were isolated from Chengdu Longquan refuse landfill and Yibin paper mill. They could be used to make compound inoculum that producing methane with the existing Methanogens utilized different substrate. With using anaerobic activated sludge be solid fixture, the process had been designed to produce solid compound inoculum. Strain RY3 possessed excellent capacity of acid and alkali-tolerant. The pH-tolerant scale of RY3 was 5.5～10.5 and its optimum pH value for growth was 6.0～8.0. RY3 was G+, long-rod shape, monothetic and nonmotile, the colony was pale yellow with suborbicular-shape. Formate or H2+CO2 but not acetate was utilized by RY3 as sole C-source, and it was very sensitive to chloramphenicol. Besides, strain RY3 grew fastest at 55℃～65 and 0℃～2% NaCl. Characteristics of modality and physiology with sequence analysis of the 16s rDNA gene of strain RY3 preliminarily showed that it was Methanothermobacter thermautotrophicus. The experiments indicated that the time which began to produce methane with the highest velocity could be shortened two third by adding RY3 in one week, and the total methane production also was 1.8 times than before. Strain SH4 possessed wide scale of growing pH（5.5～9.5）and excellent ability of acclimatizing itself to acid-alkali. The methane production had no apparent difference among those cultivated in different initial pH（6.0～8.0）after three days and equaled to the maximum production basically. Cells of SH4 were G+, short-rod sharp, monothetic and nonmotile. The colony was pale yellow with suborbicular-shape. Formate or H2+CO2 but not acetate was utilized by SH4 as sole C-source, and it was very sensitive to chloramphenicol. Besides, it grew fastest at pH 7.0，55 ℃～65 and 0℃～2% NaCl concentration. The experiment indicated the time that began to produce methane could be shortening one third by adding SH4. And the total methane production also rose apparently. Characteristic of modality and physiology with sequence analysis of the 16S rDNA gene of strain SH4 demonstrated it was Methanobrevibacter arboriphilus. The activated sludge was utilized as fixture, mixed with culture medium and inocolum, that the solid compound inoculum could be produced by anaerobic fermentation. The compound inoculum could grow between pH 5.5～9.5, 15℃～65. It demonstrated the compound inoculum ha℃ve great ability of adapting to circumstance. In the experiment that making pig manure be substrate and taking the anaerobic sludge producing methane that cultured in long term in laboratory to be comparison, the concentration of methane in fermentation added compound inoculum almost equal to the comparison at 20℃, but the volume of gas production could be a little higher. The gas production everyday inoculated compound inoculum was 1.59 times to comparison. The time that the concentration of methane to maximum could be shortening by two third by adding compound inoculum, and the total gas production was 2.7 times to comprison while the total methane production was 2.8 times. If take the no inoculum be the comprasion, anaerobic fermentation added compound inoculum made the concentration of methane to 50% in 2 weeks but the comparison only to 4.3% at 20℃. The time that the concentration of methane to 50% by adding compound inoculum only need 1 week, but the comparison need 2 weeks at 50℃.

Ultrahigh compression of water using intense heavy ion beams: laboratory planetary physics

Intense heavy ion beams offer a unique tool for generating samples of high energy density matter with extreme conditions of density and pressure that are believed to exist in the interiors of giant planets. An international accelerator facility named FAIR (Facility for Antiprotons and Ion Research) is being constructed at Darmstadt, which will be completed around the year 2015. It is expected that this accelerator facility will deliver a bunched uranium beam with an intensity of 5x10(11) ions per spill with a bunch length of 50-100 ns. An experiment named LAPLAS (Laboratory Planetary Sciences) has been proposed to achieve a low-entropy compression of a sample material like hydrogen or water (which are believed to be abundant in giant planets) that is imploded in a multi-layered target by the ion beam. Detailed numerical simulations have shown that using parameters of the heavy ion beam that will be available at FAIR, one can generate physical conditions that have been predicted to exist in the interior of giant planets. In the present paper, we report simulations of compression of water that show that one can generate a plasma phase as well as a superionic phase of water in the LAPLAS experiments.

抗氧化剂对渗透胁迫下沙棘叶片膜脂过氧化的保护作用

以沙棘叶片为材料 ,研究了外源抗氧化物质 Vc、VE、β-胡萝卜素等对 PEG渗透胁迫下细胞膜的保护作用。结果表明 :加入外源 Vc、β-胡萝卜素能有效保护膜系统 ,使膜透性和丙二醛在胁迫条件下增加小于对照 ,尤其在胁迫前期作用明显 ,而对叶绿素的保护作用在后期表现更突出 ,使叶绿素含量维持在较高水平 ;外源 VE 对防止膜透性增加作用不大 ,对减低丙二醛含量与保护叶绿素方面有所贡献。同时也证明沙棘叶片内 Vc在渗透胁迫下含量下降 ,而 Pro含量显著升高。证明这些物质是构成沙棘抗旱性的重要基础。

Evolution of the interfacial tension between polydisperse "immiscible" polymers in the absence and in the presence of a compatibilizer

The interfacial tension sigma between two polyisobutylenes (PIB) of dissimilar polydispersity and two polydisperse samples of poly(dimethylsiloxane) (PDMS) was measured as a function of time by means of a pendent drop apparatus at different temperatures ranging from 30 to 110 degreesC. In addition to three of the four possible binary blends, the time evolution of sigma was also determined for one ternary system, where the PIB phase contained 0.03 wt % of a diblock copolymer poly(isobutylene-b-dimethylsiloxane). The pronounced decrease of sigma with advancing time, observed in all cases, is attributed to the migration of the interfacially active lower molecular weight components of the homopolymers and of the compatibilizer into the interphase. Several days are normally required until a becomes constant. These time independent values are not considered as equilibrium data, but accredited to stationary states. A kinetic model is established for sigma(t), which enables a detailed investigation of the rates of transport of the different migrating species of average molar mass of M.

Investigation of the self-accelerating process of ascorbic acid by in-situ circular dichroism spectroelectrochemistry

The electrode reaction process of ascorbic (Vc) was studied by in-situ circular dichroic(CD) spectroelectrochemistry with a long optical path thin layer cell on glassy carbon(GC) electrode. The spectroelectrochemical data were analyzed by the double logarithmic method together with nonlinear regression. The results suggested that the mechanism of Ve in pH 7.0 phosphate buffer solution at GC electrode was a two-electron irreversible electrooxidation followed by adsorption of the oxidation product. That is a self-accelerated process. Some kinetic parameters at free and at adsorbed electrode surface, i.e, the formal potentials, E-0' = 0.09 V, E-a(0') = 0.26 +/- 0.02 V; the electron transfer coefficient and number of transfered electron, alpha n = 0.41, alpha(a)n = 0.07;the standard heterogeneous electron transfer rate constant, k(0) = 8.0 x 10(-5) cm.s(-1), k(a)(0) = 1.9 x 10(-4) cm.s(-1) and adsorption constant, beta = 102.6 were also estimated.

IDDM患儿全血自由基和血清过氧化脂质、维生素E含量

糖尿病是一种糖能量代谢障碍性疾病。其发病率在逐年升高。有关糖尿病因及发病机制的研究一直是人们共同关注的焦点。最近自由基与糖尿病的关系引起了我们的极大兴趣。本文为我们近期所作的有关IDDM患儿全血自由基(FR)含量的研究结果,同时又测定了血清过氧化脂质(LPO)及维生素E(VE)含量,现一并报告如下