Structural Changes in Titin and Nebulin Filaments Specific to Calcium Ions at 0.1 mM: Factors of Meat Tenderization During Postmortem Aging

ABSTRACT Postmortem structural changes in titin and nebulin filaments were investigated by incubating isolated myofibrils in a solution containing 0.1 mM calcium ions and various concentrations of a protease inhibitor. The inhibition curves showed 2 abnormal steps with increases in the concentration of leupeptin or calpastatin domain I. While the amounts of unchanged titin and nebulin were constant in the 1st step, the 2nd occurred at higher protease inhibitor concentrations. These facts indicated that excess amounts of leupeptin and calpastatin domain I caused deterioration in titin and nebulin properties, thus interfering with the binding of calcium ions. We concluded that the severance of titin and nebulin filaments in the 1st step were induced by calcium ions at 0.1 mM.     

单分散六边形扁平溴碘化银微晶的结构与性能的研究

应用可控双注仪制备了一系列碘含量相同而碘在微晶中分布不同的单分散六边形扁平溴碘化银乳剂。用扫描电镜（ＳＴＥＭ）与Ｘ－射线能谱仪（ＥＤＳ）对单个微晶进行了微区分析，并用介电损耗，微波光导等方法研究了此类乳剂微晶的结构与性能的关系。结果表明：严格控制微晶成核、成熟、生长三个阶段的条件，可制得含六边形颗粒９２％以上的扁平溴碘化银乳剂，颗粒大小变化系数小于１２％。此外碘在微晶中的分布明显影响微晶的电性质和     

β－C_2S固溶体稳定的热力学研究

从热力学理论出发，利用Ｘ射线衍射定性和定量的方法，对β－Ｃ＿２Ｓ固溶体的稳定性进行了分析和研究。经热力学理论推导得出β－Ｃ＿２Ｓ稳定的热力学条件，即掺入的微量元素的化学位μ＿ｉ须小于β－Ｃ＿２Ｓ的反应自由焓△Ｇ＿β，μ＿ｉ＜△Ｇ＿β．并定量地计算出一种微量元素稳定β－Ｃ＿２Ｓ的临界掺加量为；多种微量元素对β－Ｃ＿２Ｓ的稳定性判断条件为：     

Structural Description of Polyaromatic Nucleus in Residue

The proton nuclear magnetic resonance spectroscopy （1H-NMR）, the synchronous fluorescence spectrometry （SFS） and the ruthenium ions catalyzed oxidation （RICO） method were used to determine the chemical structure of polyaromatic nucleus in Oman residue fractions. The results of 1H-NMR analyses showed that the average numbers of aromatic rings in the aromatics, resins and asphaltenes units were 3.2, 5.6 and 8.2, respectively. SFS was used to investigate the distribution of aromatic rings in residue fractions, the main distribution range of aromatic rings in aromatics, resins and asphaltenes were 3 4 rings, 3--5 rings and more than 5 rings, respectively. The aromatic network in residue fractions was oxidized to produce numerous carboxylic acids. The types and content of benzenepolycarboxylic acids, such as phthalic acid, benzenetricarboxylic acids, benzenetetracarboxylic acids, benzenepentacarboxylic acid and benzenehexacarboxylic acid disclosed the condensed types of aromatic nuclei in the core. The biphenyl fraction （BIPH）, the cata-condensed fraction （CATA）, the peri-condensed fraction （PERI） and the condensed index （BCI） were calculated based on the benzenepolycarboxylic acids formed. The results implied that there was less biphenyl type structures in all residue fractions. The aromatics fraction was almost composed of the cata-condensed type system, and the asphaltenes fraction was wholly composed of the peri-condensed type system, while in the resins fraction co-existed the two types, herein the peri-con- densed type was predominant over the cata-condensed type. Based on the analytical results obtained in the study, the components --aromatics, resins and asphaltenes -- were given the likely structural models.     

部分种子成分的特征X射线在等效生物材料中衰减的测定

用Ｓｉ（Ｌｉ）探测器实现了Ｎａ、Ｍｇ、Ｓ、Ｃｌ的特征Ｘ射线在有机膜中的相对衰减以及与Ｏ、Ｋ元素的特征Ｘ射线能量相当的Ｘ射线或轫致辐射在有机膜中的相对衰减，分别得出了它们减的数学描述，并把实验得到不同能量的Ｘ射线在有机膜中的质量吸收系数与Ｂｅｒｋｅｌｅｙ的ＯＣＧ软件计算出的结果相比，相关都小于３０％。     

水性聚氨酯电导率与聚沉值的研究

研究了软（硬）段含羧基的水性阴离子纳米聚氨酯体系的n(NCO)/n(OH)比值，COOH的质量分类，反离子各类，合成方法与电导率关系及产生的原因；探讨了该体系的n(NCO)/n(OH)值，COOH的质量分数，合成方法与临界聚沉值（Cc.c)的关系和规律。并分析，比较了软（硬）段含羧基的水性阴离子聚氨酯体系电导率与Cc.c二者关系，得出了随COOH的质量分数升高，二者变化相同，随n(NCO)/n(OH)比值升高,二者变化相反的结论。     

新型阳离子聚合物NCP的合成及应用

介绍了用高分子反应法在固态条件下合成高阳离子度阳离子聚合物NCP的方法,确定了其最佳反应条件,测定了聚合物阳离子度和反应效率.采用L9（34）正交试验法得出合成NCP的最佳反应条件为：聚合物与阳离子化试剂质量比为11：3;催化剂用量为1.072%,反应时间为2.5 h;反应温度为80℃.实验结果表明,在反应体系中加入催化剂和少量有机或无机溶剂可显著提高反应速率和效率;使用少量润湿剂,可最大限度地限制副反应,造成反应部位的局部浓度高,提高反应效率.阳离子聚合物NCP可作为增粘降滤失剂用于配制正电性钻井液,效果优良,且耐温性能良好,同时基于阳离子与阴离子聚合物在溶液中生成凝胶状沉淀物的特性,NCP还可用于解决注聚区块生产井产出水中含高浓度聚合物的问题.     

新型处理药剂（EP-110）处理各种重金属离子的实验研究

各行各业生产过程中会产生大量废水,重金属离子污染物是其中的重要控制指标,传统的处理方法不能完全解 决这类污染。本文通过大量的实验数据,对新型的处理药剂(EP-110)处理各种重金属离子的性能做了全面的测试、分析,并 提出了使用方法。     

In situ13C NMR study of tert-butanol interaction with moderately concentrated sulfuric acid

An in situ NMR study of tert-butanol dehydration in 95 and 85% sulfuric acid did not indicate the formation of tert-butyl cations as active reaction intermediates. Instead, only NMR lines from oxonium ions under the condition of fast exchange with water and the acid were observed. It is most likely that, in the concentrated acid, the active intermediates of this reaction are represented by tert-butyl sulfuric ester which probably is a precursor of invisible tert-butyl carbenium ions representing short-lived excited or transition states.     

Pitting corrosion of Cr–Mn–N steel in sulphuric acid media

The resistance to pitting corrosion of austenitic stainless steel Cr18Mn12N has been studied in model solutions of sulphuric acid (0.5 m) containing chloride ions (0.5 m). The cyclic potentiodynamic method has been employed to investigate the effects of chloride ions and agitation rate on the pitting and repassivation potentials. Electron and optical microscopy, electron diffraction spectroscopy and atomic absorption spectrometry have been used to detect the surface sites for pit formation and the growth of pit nuclei. The results obtained with chromium–manganese–nitrogen steel have been compared with those of austenitic Cr18Ni9 stainless steel. A similarity in pit initiation is established, while steel composition exhibits no significant effect. Cr18Mn12N steel is less prone to repassivation as compared with Cr18Ni9 steel.