广东某高校学生膳食硒摄入状况

为了解广东大学生膳食硒的摄入状况,进而了解广州市居民的膳食硒摄入状况,采用单纯随机抽样的方法随机选取广东某高校某班学生10人,男女生各半,用双份饭法收集这10名学生连续7d内每天摄入的全部食物（包括饮水、饮料、零食等）,共70份样品,用荧光分光光度法测定了各样品的硒含量,得到学生在调查期间膳食硒的摄入状况。结果表明,男、女生人均膳食硒摄人量分别为86．51μg／d和69．92μg／d,学生总体人均膳食硒摄入量为78．22μg／d。该校学生膳食硒的摄入量达到了中国营养学会推荐的参考摄入量（50—250μg／d）的要求。     

SPCE-微型DPSA-1仪同步快速检测蔬菜中的铅、镉、铜

以优化的微波消解法进行样品预处理,用微型DPSA-1仪结合丝网印刷碳电极,通过微分电位溶出法对蔬菜中的铅、镉、铜进行同步快速检测。结果表明,在1～840μg/L(相当于蔬菜中铅、镉、铜含量为0.0125～10.5mg/kg)范围内呈现良好的线性关系,铅的相关系数为r=0.9977,检出限为0.42μg/L(S/N=3);镉的相关系数为r=0.9976,检出限为0.34μg/L(S/N=3);铜的相关系数为r=0.9958,检出限为1.36μg/L(S/N=3)。研究了检测过程中存在多种干扰离子对于铅、镉、铜检测的干扰情况。试验检测26种蔬菜,所得检测结果与国标检测法进行t检验,无显著差异。与常规的检测技术相比,本法同步检测蔬菜中的铅、镉、铜具有更经济、简便、快速等优点,可实现样品的高比例筛检,还有望作为推广应用于其它类型食品和环境样品中铅、镉、铜快速检测的基础模型,具有很好的应用潜力和广阔的应用前景。     

重庆市某高校学生膳食铬摄入水平的测定

为了解重庆市某高校学生膳食铬的摄入水平,随机选取调查对象120人,双份饭法采样食物,用火焰原子吸收分光光度法测定了膳食中铬的含量。结果表明,大学生膳食铬的平均摄入量男生为4.68 mg/d,女生为3.80 mg/d,分别是适宜摄入量(adequate Intake,AI)的23.4倍和19倍,也显著超过了铬的每日允许摄入量(acceptable daily Intake,ADI)1.0 mg/d。可见高校学生膳食铬摄入水平超过了推荐膳食摄入量和安全限量,但其对健康的影响有待进一步明确。     

平煤二小学生膳食状况调查

为了解平煤二小学生的膳食结构,合理安排学生膳食提供依据,用称重法对134名学生的膳食进行了5日的调查。结果表明,钙元素摄入严重不足,仅占供给量(RDA)的40．56％;其次是维生素A、胡萝卜素、核黄素摄入不足,分别为供给量(RDA)的62．32％、51．97％、54．17％;脂肪偏高,碳水化合物偏低。提示该校学生营养素摄入不均衡,钙元素摄入量不足尤为突出,膳食结构需要改进。     

微波消解-石墨炉原子吸收光谱法测定纸质食品包装材料中的痕量镉

建立了微波消解–石墨炉原子吸收光谱法测定纸质食品包装材料中痕量镉的检验方法。样品经微波消解后,以硝酸镍为基体改进剂,试验确定了石墨炉原子吸收法测定镉的最佳仪器条件。镉的质量浓度在0～10μg/L与吸收峰面积呈良好的线性关系,线性相关系数r=0.9997,检出限为0.025μg/L。将该法用于纸质食品包装材料中痕量镉的测定,并进行加标回收试验,回收率为96.0%～105.5%,相对标准偏差不大于4.4%(n=10)。     

直接进样电热蒸发-原子荧光光谱法快速测定蒸馏酒中镉

为了快速低成本测定蒸馏酒中痕量重金属镉,利用钨丝电热蒸发器作为直接进样装置,与原子荧光光谱仪原子化器直接连接,构建了用于蒸馏酒中镉测定的直接进样原子荧光光谱检测系统(W-coil ETV-AFS),并对工作气体的气氛和流速、灰化和蒸发电压、样品承载量等参数进行了优化,建立了蒸馏酒中镉的直接进样快速检测方法。在最优条件下,Cd的检出限(LOD)为0.06μg/L(进样量为50μL),在0.5~100μg/L线性范围内回归系数(R²)为0.997;在5μg/L水平下,9个典型蒸馏酒样品的加标回收率在86.0%~116%,相对标准偏差RSD≤8.0%(n=3)。可以直接导入样品,无需复杂的前处理过程,具有良好的灵敏度、准确度和精密度,非常适合蒸馏酒中痕量镉的快速测定。     

ICP–MS法测定食品接触纸制品中铬、镍、砷、镉、铅、汞

建立电感耦合等离子体质谱法(ICP–MS)测定食品接触纸制品中铬、镍、砷、镉、铅、汞6种重金属含量的方法。样品经微波消解处理后用ICP–MS进行测定,内标法定量。在优化实验条件下,测定汞元素的线性范围在0~10μg/L之间,测定铅、镉、铬、镍、砷元素的线性范围在0~100μg/L之间,相关系数均大于0.999。各元素的检出限为0.001~0.1 mg/kg,加标回收率为89.3%~116.0%,测定结果的相对标准偏差为3.5%~7.9%(n=6)。该方法样品处理简单,检测灵敏度高,适用于食品接触纸制品中铬、镍、砷、镉、铅、汞的检测。     

蒸气发生-原子荧光光谱法测定痕量镉(Ⅱ)的研究

研究了在硼氢化钠-1,10-二氮杂菲-钴(Ⅱ)体系中镉的荧光信号,发现1,10-二氮杂菲-钴(Ⅱ)能显著提高镉的荧光强度。据此,建立了一种蒸气发生-原子荧光光谱法测定痕量镉的新方法。优化了测定镉的实验参数,在优化的实验条件下。方法的检出限为0.014μg/L,线性范围为0~50μg/L,相关系数r=0.9971,相对标准偏差不超过3.2%。用该法测定了水系沉积物标准样品中镉的含量,取得了满意结果。     

氢化物发生–原子荧光法测定水中的镉

采用氢化物发生–原子荧光光谱法对水中的镉进行测定。在0.24 mol/L盐酸介质中,以1.2 mol/L钴溶液为信号改进剂、2 g/L磺基水杨酸钠为基体改进剂,镉与硼氢化钾(质量浓度为25 g/L)反应生成镉的挥发性物质。镉的质量浓度在0~5μg/L范围内与荧光强度呈良好的线性,线性相关系数r=0.999 7,方法检出限为0.021 5μg/L,测定结果的相对标准偏差为1.89%(n=7),加标回收率为88.0%~113.2%。该方法操作简单,灵敏度高,适用于水质中镉元素的测定。     

氢化物发生-原子荧光光谱法测定植物样品中的硒

本文应用氢化物发生-原子荧光光谱法对植物样品中硒总量的测定方法进行研究。优化了植物样品预处理,选取H2O2-HNO2(1∶5,V/V)体系微波消解;优化了测定中载流与还原剂的浓度,选定载流HCl浓度为15%,还原剂KBH4浓度为1.5%。该方法测定植物样品中的总硒,线性范围为0~100μg/L(r=0.9995),检出限为0.0906μg/L,回收率在90.0%~112.2%范围,精密度(RSD)小于0.39%。该方法操作简单、灵敏度高、检出限低,适合对植物样品中硒总量的分析测定。     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。