硫酸锌与L-亮氨酸配合物行为的研究

锌是生命元素,缺锌引起的各种疾病已引起全世界的共同注意.L-α-氨基酸是人体蛋白质的基本结构单元.α-氨基酸锌作为添加剂在药物、食品和化妆品中有广阔的应用前景[1～3].L-α-亮氨酸(简写为Leu)是人体必需但在人体内又不能合成的氨基酸之一,必须从食物中得到.文献中尚未见亮氨酸锌的报导.本文用半微量相平衡方法[4]研究了ZnSO4-Leu-H2O体系在25℃的相化学行为,发现该体系中未形成新化合物.改进文献方法合成了未见文献报导的Zn(Leu)SO4·12H2O和Zn(Leu)2固态配合物,并研究了它们的物理化学性质.1实验部分1.1试剂与仪器　　Zn…     

Synthesis of Z and E-(2',5'-dimethoxyphenyl)-methylene-butyrolactones

Pseudotaxlactone was isolated by Zhang1 from Taxaceae plant pseudotaxus chienii(Cheng) Cheng. It's structure was tentatively assigned as 5-(4-hydroxy-3,5- 20%(Z,9), 4%(E,8).The intermediate 7 was synthesized using 2,5-dimethoxy-phenyl acetic acid as astarting material. However, cyclization reaction gave Z-(2,5-dimethoxy-phenyl)methylene-butyrolactone 9 (20%) and E-(2,5-dimethoxy-phenyl)-methylelactone 8 (4%), instead of the desired counterpart with endocyclic unsaturation. Thereaction of t…     

Activity and Osmotic Coefficients from the Emf of Liquid Membrane Cells. IX: Mn(ClO4)2 and MnSO4 in Water at 25°C

The relative activity coefficients of MnSO₄ and Mn(ClO₄)₂ were measured downto about 5×10^–5 mol-kg^–1 by means of cells with ion-exchange liquid membranes.The measurements at high dilution provide an answer to the age-old problem ofabsolute values of the activity coefficients for MnSO₄. They also lead to acorrection of the activity coefficients for Mn(ClO₄)₂, whose literature values arefound to be biased by ca. 6.5%. Like other bivalent metal sulfates, MnSO₄does not obey the Debye—Hückel law inasmuch as negative instead of positivedeviations from the limiting law are observed in the dilute regions. The possibilityfor this kind of behavior to denote ion association is discussed. The best-fitparameters of Pitzer's equation, able to provide accurate values of the activityand osmotic coefficients of the two salts for any concentration, are reported.     

十二烷基硫酸钠减慢二苯胺—4—重氮盐及重氮树脂在水溶？…

以二苯胺重氮盐（ＤＤＳ）为模型化合物,系统考察了其在水中热分解反应与十二烷基硫酸钠（ＳＷＳ）的浓度以及溶液中小分子电解质的关系。结合荧光分析结果,证实了ＤＤＳ及重氮树脂（ＤＲ）在ＳＤＳ溶液中热稳定性的提高是由于ＤＤＳ和ＤＲ分子与ＳＤＳ分子间的疏水相互作用和静电吸引作用使它们同ＳＤＳ分子共同形成混合预胶束或胶束,通过预胶束或胶束的静电及极性效应使其中的ＤＤＳ和ＤＲ分子上的重氮基得到保护。随着ＳＤＳ浓     

维多利亚蓝B分光光度法测定硫酸软骨素

在pH 4.0醋酸-醋酸钠缓冲液中,阳离子染料维多利亚蓝B在614 nm处有一吸收峰。它与硫酸软骨素(Chs)反应生成缔合微粒后导致614 nm处的吸收峰降低,其吸光度差值与Chs浓度在0.1～5 μg·mL-1范围内呈良好的线性关系。据此建立了一个简便、快速、准确测定硫酸软骨素含量的分光光度新方法。该法已用于合成样及康得灵注射液样品分析,结果满意。     

可见吸收光谱线型参数分析法测定十二烷基硫酸钠临界胶束浓度

于浓度相同的结晶紫（CV）溶液中,加入不同浓度的十二烷基硫酸钠（SDS）组成一系列含有相同浓度CV和不同浓度SDS的混合溶液。在可见光区内对每一混合溶液测定其吸收值时,可见随SDS浓度的逐步递增,在CV-单聚体吸收峰的吸收值逐渐减少;而在CV-二聚体吸收峰的吸收值逐渐增加,且随CV-二聚体浓度增加而出现的CV-二聚体与CV-单聚体的吸收光谱线相互严重重叠,光谱形状也发生渐变。运用分光光度计所配备的Origin 7．5软件中储存的高斯多峰拟合法,可自动进行重叠光谱的解析和各光谱参数（包括y0,A1,A2,ω1,ω2,xc1及xc2）的拟合计算。文中还证示,每一参数与SDS浓度之间有明显的相关性,在两者之间所作的曲线上可找到明显的转折点,与转折点相对应的、在横坐标上的SDS浓度值即为SDS的临界胶束浓度（CMC）值。文中首次报道了用吸收光谱的半峰宽对SDS浓度作图所得曲线上的转折点求得SDS的CMC值。     

在相反电荷表面活性剂存在下阳离子瓜尔胶水溶液流变行为

合成了阳离子瓜尔胶(CG),研究了其水溶液在十二烷基硫酸钠(SDS)存在下的流变行为．测定结果表明,随SDS浓度的增加,溶液零切黏度增加了3个数量级以上．小幅振荡剪切实验结果表明模量几乎和SDS浓度无关,但是驰豫时间则随着SDS浓度增加而迅速增加．因此,SDS的加入将会使交联点的强度增加,但是不会改变交联点密度．SDS对CG流变行为的影响可以用两阶段模型加以描述．在SDS存在下CG水溶液流变行为主要受到由SDS胶束形成的交联点的控制．根据Arrhenius公式得到的瓜儿胶水溶液的流动活化能在将SDS分子疏水尾端从胶束移到水相之中所需能量是一致的.     

硫酸钡重量法测定硫条件实验探讨

铁矿石中的硫含量是衡量钢铁冶炼性能的重要指标,检测硫含量具有重要的意义.采用国家标准GB/T 6730.16—2016中的硫酸钡重量法测定硫,探讨熔剂用量、氯化钡浓度以及沉淀时的保温时间和保温温度对硫含量测定的影响,获得测定铁矿石中硫含量的最佳实验条件.结果显示,2.0000 g标准铁矿石(硫含量为0.036％)样,熔...     

Liquid chromatography coupled to tandem mass spectrometry methods for the selective and sensitive determination of 24S-hydroxycholesterol,its sulfate,and/or glucuronide conjugates in plasma

24S-hydroxycholesterol (i.e., cerebrosterol, 24S-OH-Chol) is the main form of cholesterol elimination from the brain. Liquid chromatography–tandem mass spectrometry methods were developed for the quantification of the total and unesterified/unbound fractions of 24S-OH-Chol, its monosulfate, monoglucuronide, and diconjugate derivatives (24S-OH-Chol-3sulfate [3S], 24S-OH-Chol-24glucuronide [24G] and 24S-OH-Chol-3S, 24G, respectively) in human plasma. Linearity, precision, accuracy, and extraction recovery were validated within the typical physiological and pathological ranges of concentrations for each compound. The lower limit of quantifications was 2.00, 0.33, 0.26, and 0.74 ng/ml for 24S-OH-Chol, 24S-OH-Chol-24G, 24S-OH-Chol-3S, and 24-OH-Chol-3S, 24G, respectively. Extraction recovery values in total and unbound plasma fractions were also analyzed in murine and monkey plasma and varied from 73% in mouse to 113% in cynomolgus monkey. The methods could rapidly (less than 7 min) quantify individual compounds with high sensitivity, accuracy (bias ≤15%), and reproducibility (coefficient of variation [CV] ≤ 17%). Their clinical applications were validated by measuring levels of the 4 compounds in samples from 20 noncholestatic donors, 5 cholestatic patients suffering from primary biliary cirrhosis, and 10 patients suffering from biliary stenosis. Results highlight the abundance of 24S-OH-Chol in the total fraction and the abundance of 24S-OH-Chol-3S and 24G in the unbound ones. While the latter strongly accumulate in plasma fractions of cholestatic patients, levels of 24S-OH-Chol remained similar to those of healthy donors. Our results indicate that this approach is suitable for monitoring cerebrosterol and its conjugates in large-scale clinical studies.     

Tripodal,Squaramide-Based Ion Pair Receptor for Effective Extraction of Sulfate Salt

Combining three features—the high affinity of squaramides toward anions, cooperation in ion pair binding and preorganization of the binding domains in the tripodal platform—led to the effective receptor 2. The lack of at least one of these key elements in the structures of reference receptors 3 and 4 caused a lower affinity towards ion pairs. Receptor 2 was found to form an intramolecular network in wet chloroform, which changed into inorganic–organic associates after contact with ions and allowed salts to be extracted from an aqueous to an organic phase. The disparity in the binding mode of 2 with sulfates and with other monovalent anions led to the selective extraction of extremely hydrated sulfate anions in the presence of more lipophilic salts, thus overcoming the Hofmeister series.