软X射线对血液有形成分表面电荷的影响——2、淋巴细胞和血小板膜电荷的变化

软X射线不仅能引起红细胞表面电荷的变化,同时也能导致淋巴细胞和血小板表面电荷下降,表现为照射后它们的电泳率下降。低剂量范围内,这种电荷的变化是暂时性的,照后4小时降到最低点,24小时后恢复到对照的水平。细胞电泳率的下降与辐射剂量相关。淋巴细胞是一个复杂的细胞群,正常状态下,按细胞在电场中泳动速度的快慢,可分为两个组分:快峰为T细胞,慢峰为B细胞。软X射线照射以后,T和B细胞的电泳率皆减慢,频数分布峰值下降,离散度加大。血小板成分单一,电泳率较一致。 从照射浓集的血小板再加回自身血浆中电泳率的下降较照射血浆再加到血小板中的电泳率下降大得多;受照射的血小板在磷酸缓冲液中电泳率下降较在血浆悬液中严重得多;2000 rad照后,悬浮于血浆中的血小板电泳率能恢复,而悬浮于磷酸缓冲液中则不能恢复,三个方面来看,血浆中可能存在抗辐射因子。超氧化物岐化酶能有效地预防血小板电泳率的下降,从而可阻止血小板的凝聚。     

Superoxide Dismutase Activities in Senescing Apple Fruit (Malus domestica Borkh.)

Total superoxide dismutase (SOD:superoxide: superoxide oxidoreductase; EC 1.15.1.1) activity and individual activities of its three different metalloenzymes, CuZn-SOD, Fe-SOD, and Mn-SOD, were investigated during senescence of apples (Malus domestica Borkh.). Total SOD activity and relative activities of its three forms varied greatly among cultivars. Activities underwent considerable change during senescence of fruit, but changes were different among cultivars. Whether fruit senesced at 0°C or 20°C had little effect on SOD activities, and application of the antioxidant diphenylamine (DPA) did not alter activities. SOD activities increased with occurrence of the physiological disorder “senescent breakdown,” but did not increase with occurrence of the disorder “superficial scald.” In a given apple cultivar, changes in total SOD activity generally paralleled activities of the different SOD forms. Such activity may reflect changes affecting food and nutritive quality of the fruit.     

卤素离子对铝合金阳极的活化作用

镓锡合金沉积子铝阳极表面，形成活化点，是含镓、锡铝合金阳极活化的根本原因。溶液中的卤素离子在氧化膜上的吸附及在其中的扩散也促进了铝电极的阳极溶解。合金元素及溶液中的阴离子通过改变铝电极表面的零电荷，影响着合金元素在铝电极表面的沉积的难易程度，从而影响着铝合金阳极的活化性能。     

几种无机阴离子对TiO_2催化活性影响的实验研究

以N掺杂TiO2试剂为催化剂,降解偶氮直接耐酸大红4BS溶液,同时外加4种浓度不同的阴离子溶液,探讨了HCO3-,F-,NO3-,H2PO4-等阴离子对N/TiO2化学试剂催化活性的影响。实验表明,HCO3-,F-,NO3-,H2PO4-等阴离子对N/TiO2化学试剂的催化活性有显著影响。因此,可以通过外加不同的离子来提高或降低N/TiO2的活性。     

Equilibrium and kinetic studies of the extraction of chelated copper(II) anions with Aliquat 336

The equilibrium and kinetics of solvent extraction of Cu²⁺ from aqueous solutions containing equimolar EDTA with Aliquat 336 in n‐decanol and kerosene at 298 K were investigated. The concentrations of Cu²⁺ (8–50 mol m^?3), Cl^? (5–60 mol m^?3), and Aliquat 336 (20–100 mol m^?3) were varied. A semi‐empirical model with three parameters was proposed to describe the equilibrium behavior, in which the non‐idealities in both aqueous and organic phases were considered. Over the ranges studied, the model agreed reasonably well with the experimental data (standard deviation, 15%). The forward and backward reaction rate constants were determined as (5.31 ± 0.16)×10^?6 m^9/4 mol^?3/4 s^?1 and (2.62 ± 0.09)×10^?7 s^?1, respectively, at 298 K. An interfacial reaction mechanism was proposed, which revealed that the reaction between the chelated anions and trimeric amine molecules at the interface was rate limiting. The derived rate laws were consistent with the experimental results. © 2002 Society of Chemical Industry     

共存阴离子对核酸阻锈剂在模拟混凝土孔溶液中钢筋阻锈作用的影响

将一种含有长度在20～80个碱基的各种引物的混合溶液溶解在核酸缓冲液中作为核酸阻锈剂,通过线性极化和电化学阻抗谱(EIS)两种电化学手段分别研究共存阴离子HCO_3~-和SO_4~(2-)对核酸阻锈剂在模拟混凝土孔溶液中对钢筋氯盐腐蚀的影响。利用X射线光电子能谱(XPS)分析了在有共存阴离子存在的模拟混凝土孔溶液中钢筋电极在核酸阻锈剂作用下表面膜的组成结构。结果表明:核酸阻锈剂具有良好的钢筋防腐蚀效果,共存阴离子HCO_3~-的存在使钢筋的腐蚀速率加快,但核酸的加入能明显减弱钢筋腐蚀倾向,具有和商用阻锈剂(主要成分为磷酸钠)基本相同的阻锈效率;共存阴离子SO_4~(2-)的存在加快了钢筋的腐蚀速率,且SO_4~(2-)的浓度较低时核酸阻锈剂的阻锈效率已经超过了同等条件下的商用阻锈剂。     

Breakdown of passive film on nickel in borate solutions containing halide anions

The effect of Cl⁻, Br⁻ and I⁻ anions as aggressive agents on the anodic behaviour of nickel electrode in deaerated Na₂B₄O₇ solutions have been investigated by galvanostatic polarization technique. Lower concentrations of the halide anions have no effect on the mechanism of nickel passivation. An increase in the halide anions concentration causes oscillation of the potential in the oxygen evolution region. This could be attributed to the destruction of the passivity by halide anions and repassivation of the film by anodic current and/or OH⁻ anions. Higher aggressive anion concentrations cause breakdown of the passive film and initiated pitting corrosion. As the temperature increases, the breakdown potential is shifted towards the more negative direction. On the other hand, as the pH of the solution increases, the breakdown potential is shifted toward more positive direction, indicating increased protection of the passive film. The activation energy, , of the oxide film formation in the presence of Cl⁻ anions was calculated and was found to be 21 kJ/mol.     

锰酶及其模拟物研究进展

对生物体内和模拟的含锰金属酶，即含锰超氧化物歧化酶(Mn—SOD)、含锰的过氧化氢酶(Mn—catalase)及含锰的光合成氧释放配合物(Mn—OEC)的结构、活性部位、催化作用机理及其模型化合物的研究进展进行了综述。     

电离辐射及超氧阴离子基对人血淋巴细胞姐妹染色单体交换的诱发作用

用姐妹染色单体交换(SCE)作为指标,研究了~(60)Coγ射线辐照及NADH-PMS(吩嗪硫酸甲酯)系统中产生的超氧阴离子自由基(0_2~(·-))对胎儿脐血淋巴细胞染色体的损伤作用,及活性氧清除剂SOD和甘露醇的保护作用。结果显示γ射线及0_2~(·-)都能诱发细胞SCE频率显著升高,且存在一定的剂量-效应关系。SOD及甘露醇对0_2~(·-)诱发的损伤有明显的保护作用。     

常见蔬菜消除超氧阴离子作用的研究

用核黄素光化学氧化光度法研究了南瓜、玉米、大蒜、苦瓜、空心菜、西红柿、胡萝卜、韭菜花8种常见蔬菜对超氧阴离子的消除作用。结果表明这些蔬菜均具有消除超氧阴离子的作用;煮沸20min,玉米和南瓜的消除超氧阴离子能力减弱约30％,空心菜的有所上升,而大蒜、苦瓜、西红柿、胡萝卜、韭菜花的消除作用均没有变化。将吸光度随这八种蔬菜提取液加入量的变化趋势与维生素C的相比较,提出蔬菜消除超氧阴离子的作用主要是依靠维生系C以外的超氧化物歧化酶等物质。