稀土离子对大鼠肝细胞核脂质过氧化的影响

用光度法测定丙二醛 (MDA)研究不同浓度La3 +,Ce3 +,Pr3 +,Nd3 +,Eu3 +对大鼠肝细胞核脂质过氧化的影响。结果表明 :稀土离子在 1×10 - 4 ～ 1× 10 - 6mol·L- 1 浓度范围内能抑制振荡温育或H2 O2 引起的脂质过氧化 ,且与浓度正相关。但是对大鼠肝细胞核用稀土离子处理一定时间 ,稀土离子Eu3 +对脂质过氧化的抑制作用明显减弱 ,甚至会导致脂质过氧化加强     

熔融织构生长强磁浮YBCO超导块材的取向和结构

采用熔融织构生长法结合顶部Ｓｍ１２３籽晶技术，成功地制备了直径为２０ｍｍ的ＹＢＣＯ超导块材。该块材具有极强的磁性能。用Ｘ射线θ／２θ扫描和Φ扫描分析其结构表明，样品在三维方向上具有很强的择优取向，其ｃ、ａ、ｂ轴方向分别与Ｓｍ１２３籽晶的ｃ、ａ、ｂ轴方向一致，并具有类似单晶的结构特点。     

双波长K系数—标准加入吸光光度法同时测定锰和锌

研究应用双波长K系数—标准加入吸光光度法同时测定锰和锌二组分混合物.试验确定了锰和锌测定中K_(Mn)与K_(Zn)的回归方程.对合成试样、人发试样测定,结果满意.     

稀土对人正常肝细胞株7701和人宫颈癌Hela细胞生长的影响及其诱导细胞凋亡的作用

采用MTT法考察了16种稀土元素在9×10-8~2×10-4mol.L-1浓度范围内对体外培养的人正常肝细胞株7701细胞和宫颈癌Hela细胞的生长的影响。结果表明,稀土对细胞生长的影响存在浓度依赖性;低浓度促进细胞增殖,高浓度抑制细胞生长;不同稀土离子对细胞作用强弱不同,稀土间存在轻重分组效应;不同细胞对稀土的响应不同,表现出稀土对正常细胞和癌细胞作用的某种选择性。Hoechst 33258标记细胞DNA,用激光共聚焦显微镜和流式细胞仪对稀土处理的肝细胞株7701进行形态学观察和DNA含量分析。结果表明,较高浓度的稀土作用后的肝细胞株7701出现了明显的凋亡特征,稀土表现出的细胞毒性作用,其本质是诱导细胞发生凋亡。     

Comparison of quantitative methods for analysis of polyphasic pharmaceuticals

Adequate very sensitive quantification methods are needed for the development and are also now required for the monitoring of undesirable solid form(s) as routine tests. The pre-requisite for quantitation are selectivity, sensitivity and most important the purity of standards and their proper storage, what is a challenge for metastable forms. Several analytical techniques are available such as X-ray diffraction, spectroscopy, thermal analysis and microcalorimetry. The different steps of the validation of the analytical methods and problems to be solved are discussed. Examples illustrate the different techniques and compare their possible advantages and limits. The relative standard deviation of measurements should allow for checking the homogenization procedure of mixtures for calibration. The validation should be carried out following ICH guidelines for validation of analytical methods. Comparison of different techniques in adequate concentration range add confidence in the analytical results.     

Temperature influence on hydrogen sorption in palladium limited-volume electrodes (Pd-LVE)

The effect of temperature on hydrogen and deuterium electrosorption into a palladium LVE (limited-volume electrode) has been investigated. A decrease in hydrogen capacity (H/Pd ratio) with increasing temperature has been observed. Temperature strongly influences the plots of measured H(D)/Pd values vs. potential scan rate. In addition, hydrogen absorption was found to be dependent on the composition of the surrounding electrolyte solution. These results have confirmed the hypothesis that two different mechanisms of hydrogen desorption from the palladium electrode take place, namely electrochemical oxidation and non-electrochemical recombination. Further, the ratio between the rate constants for these two processes has been found to change with temperature. Electronic Publication     

Kinetics of thermal decomposition of alkaline phosphates

Summary The thermal behavior of KH₂PO₄, NaH₂PO₄ and Na₂HPO₄ under non-isothermal conditions using TG method with different heating rates was studied. The values of the reaction rate were processed by means of Friedmans differential-isoconversional method. A dependence of the activation energy vs. conversion was observed. Therefore a procedure based on the compensation effect (suggested by Budrugeac and Segal) was applied. A less speculative data processing protocol was offered by the non-parametric kinetics method suggested by Serra, Nomen and Sempere. Three steps were observed by non-isothermal heating: a dehydration, a dimerization and a polycondensation. The differences in the intimate reaction mechanism are determined by the initial number of water molecules.