分光光度法测定铝合金中锰的不确定度评定

对分光光度法测量铝合金中锰含量的测量不确定度进行评定,分析了测量过程中不确定度的主要来源,如测量重复性、溶液浓度、溶液体积、试样溶液定容体积、分取溶液体积等,并对各不确定度分量进行了量化.对锰含量为0.80%～2.00%的铝合金,置信水平为95%时,测量结果的扩展不确定度为0.02%.     

不锈钢1Cr18Ni9Ti中铬含量测量不确定度的评定

采用国际通用的方法研究了过硫酸铵氧化容量法测定铬含量的不确定度,分析了容量法中摩尔质量、样品质量、溶液的体积、温度等因素对测量不确定度的影响,评估了各参数的标准不确定度、合成标准不确定度和扩展不确定度。找出了影响容量法测定铬含量准确度的主要原因。     

氢化物发生-原子荧光光谱法测定纯镁中铅的不确定度分析

分析了用氢化物发生-原子荧光光谱法测定纯镁中铅含量不确定度的主要来源。建立了数学模型,对测定过程中的测量重复性、标准曲线的变动性、标准溶液、试液体积、试样称量等引起的不确定分量进行了评定,计算了合成标准不确定度和扩展不确定度。评定结果表明,测量重复性和标准工作曲线引起的不确定度对总的不确定度影响最大。     

轻柴油馏程测量结果不确定度的评定

采用不确定度的A类评定和B类评定等方法,通过对轻柴油馏程测量过程分析,找出影响回收温度结果的各因素及它们之间的关系,对其结果的不确定度进行评定,得出轻柴油馏程各回收温度结果不确定度的标准计算和表示法.     

茶叶中敌敌畏残留量检测的不确定度评定

依据SN/T 1950-2007方法,对茶叶中敌敌畏残留量的测量不确定度进行分析和评定.该检测过程所产生的测量不确定度主要来源于测量重复性、标准物质纯度、标准物质称量、标准溶液稀释、样品称量、定容体积、标样溶液峰面积和样品溶液峰面积的测量.分析结果表明:茶叶中敌敌畏残留量为0.050 mg/kg时,其扩展不确定度为0....     

冷原子荧光法测定蔬菜中痕量汞的不确定度评定

对冷原子荧光法测定蔬菜中痕量汞的不确定度进行了评定。不确定度来源主要为配制标准工作溶液引入的不确定度,称取样品质量引入的不确定度,样品消化引入的不确定度,定容体积引入的不确定度,重复测定引入的不确定度。当蔬菜中汞含量为5.2μg/kg时,测量结果的扩展不确定度为0.50μg/kg。     

标准溶液测量不确定度的评定

对标准溶液测量不确定度进行合理评定，充分估计分析不确定度的来源，从量值检验时考虑到影响不确定度的各种因素，测量方法的不确定度．配制时考虑到影响不确定度的各种因素以及标准溶液的不均匀性和在有效期内的变动性所引起的不确定度等方面进行综合分析，得出其扩展不确定度。并以镍标准溶液为例作实际分析。     

石墨炉原子吸收法测定酱卤肉中铬的不确定度评定

对石墨炉原子吸收光谱法测定酱卤肉中铬的不确定度进行评定.参照GB 5009.123–2014,采用微波消解–石墨炉原子吸收法测定酱卤肉制品中铬含量,分析不确定度来源,包括测量重复性、标准工作溶液浓度、定容体积、称样质量、样品处理等,对各类不确定度分量进行评定,最终合成得到标准不确定度和扩展不确定度.当酱卤肉制品中铬含量...     

2011年约稿： 电感耦合等离子体原子发射光谱法测定铜合金中锆量的不确定度评定

讨论了采用电感耦合等离子体发射光谱法测定铜合金中锆量分析结果不确定度产生的原因。建立了数学模型,对测量重复性,标准溶液,标准曲线变动性,试液体积,试样称量,数字修约等引起的不确定分量进行评定,计算了合成标准不确定度和扩展不确定度,并给出铜合金中锆量测定结果的报告。评定结果表明：测量重复性,标准曲线线性回归引起的不确定度对总不确定度影响最大。所以,在测定中应进行多次平行测定,特别注意标准曲线的校正和绘制校准曲线所用标准样品的选择。     

基准邻苯二甲酸氢钾标定NaOH标准溶液的不确定度评定

对实验室自配的1 mol/L NaOH标准滴定溶液的浓度进行不确定度评定,建立不确定度评定程序和方法,并依据GB/T601-2002建立数学模型.确定了影响NaOH标准滴定溶液浓度的主要因素,归纳了不确定度的主要来源,建立了用基准试剂标定标准滴定溶液浓度的不确定度评定程序和方法.当NaOH标准滴定溶液浓度为1.0201 mol/L时,扩展不确定度为0.0040 mol/L.该程序和方法适用于同类型实验的不确定度评定.     

测定血清中Na 含量不确定度的评定

对血清中Na离子含量的测量不确定度进行评定。不确定度的来源主要包括Na离子标准工作液的配制过程、血清样品的定容消化制备、标准曲线拟合、钠离子各分量不确定度的合成等引入的不确定度计算出各分量的不确定度,通过合成得到测量结果的合成不确定度、扩展不确定度及测试结果的报告形式。     

ICP-AES测定铀污染土壤植物中铀的研究

采用电感耦合等离子体发射光谱(ICP-AES)对铀污染土壤植物中铀的测定方法进行了研究.在λU385.958 nm处,选择了仪器的最佳工作条件,考察了酸度和常见共存元素对测定的干扰情况,并且对比了干灰化消解和湿式消解对测定的影响.研究发现2%硝酸溶液为最佳介质,干扰离子对测定没有显著影响,干灰化消解比湿式消解得彻底.在选定条件下,方法检出限为0.18 mg·L-1,测定下限为0.61 mg·L-1,5.0000 mg·L-1的铀标准溶液的相对标准偏差RSD(n=10)为0.81%,方法回收率为96.2%～106.2%.该方法操作简单,快速.结果表明,用ICP-AES测定铀污染土壤植物样品中的铀是可行的.     

Interpretation of inorganic arsenic metabolism in humans in the light of observations made in vitro and in vivo in the rat

The toxicity of inorganic trivalent arsenic for living organisms is reduced by in vivo methylation of the element. In man, this biotransformation leads to the synthesis of monomethylarsonic (MMA) and dimethylarsinic (DMA) acids, which are efficiently eliminated in urine along with the unchanged form (As_i). In order to document the methylation process in humans, the kinetics of As_i, MMA and DMA elimination were studied in volunteers given a single dose of one of these three arsenicals or repeated doses of As_i. The arsenic methylation efficiency was also assessed in subjects acutely intoxicated with arsenic trioxide (As₂O₃) and in patients with liver diseases. Several observations in humans can be explained by the properties of the enzymic systems involved in the methylation process which we have characterized in vitro and in vivo in rats as follows: (1) production of As_i metabolites is catalyzed by an enzymic system whose activity is highest in liver cytosol; (2) different enzymic activities, using the same methyl group donor (S-adenosylmethionine), lead to the production of mono- and di-methylated derivatives which are excreted in urine as MMA and DMA; (3) dimethylating activity is highly sensitive to inhibition by excess of inorganic arsenic; (4) reduced glutathione concentration in liver moderates the arsenic methylation process through several mechanisms, e.g. stimulation of the first methylation reaction leading to MMA, facilitation of As_i uptake by hepatocytes, stimulation of the biliary excretion of the element, reduction of pentavalent forms before methylation, and protection of a reducing environment in the cells necessary to maintain the activity of the enzymic systems.     

Production of radicals in the ozonolysis of propene in air

Radical production in the ozonolysis of propene in air was monitored directly by a peroxy radical chemical amplification (PERCA) instrument at room temperature (298±2 K) and atmospheric pressure (1×105 Pa). The ozonolysis reactions were conducted in a flow tube under pseudo-first-order conditions for ozone. The decay in ozone was calculated based on reaction time tr and effective rate constant keff (keff = k1[C3H6]0)) for the ozone-propene reaction. The total radical yields relative to consumed ozone were d...     

Kinetics of dehydration in chelates of quinones involved in photosystem-II

The solid-state deaquation of thetrans- andcis-oximates of lawsone (I) and phthiocol (II) with cobalt(II) was investigated by means of non-isothermal thermogravimetry. The modes of deaquation during the thermolyses of hydrated oximates of (I) and (II) with compositions CoL₂·2H₂O were compared. The weight lossvs. temperature data were treated by using the Coats and Redfern relations. The kinetic data support a rearrangement-type mechanism for the deaquation of the oximate of phthiocol. TheE _a values for both the ligands and water molecules were found to be 23 kJ/mol.

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Zusammenfassung Mittels nichtisothermer Thermogravimetrie wurde die Dehydratation der trans- und cis-Kobalt(II)-oximate von Lawson (I) und Phthiokol (II) untersucht. Die Arten der Dehydratation während der Thermolyse der hydratierten Oximate von (I) und (II) mit der Zusammensetzung CoL₂·2H₂O wurden verglichen. Bei der Auswertung der Massenverlust-Temperatur-Daten wurden Coats-Redfern Beziehungen angewendet. Die kinetischen Daten bekräftigen einen Umlagerungsmechanismus für die Dehydratation des Oximates von Phthiokol. DieE _a Werte betragen sowohl für die Liganden als auch für Wasser etwa 23 kJ/mol.

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- - (I) (II) . I II CoL₂ · 2₂ . -. . _a , 23 · ^–1

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Use of matrix-modifiers in atomic-absorption determination of chromium in argillites

The direct atomic-absorption determination of chromium in argillites, without preliminary concentration and separation, has been studied. A map of selective flame zones for determining Cr in argillites has been designed. An express method for determining Cr in Estonian argillites has been suggested.     

Effect of vibration in processes of structure formation in polymers

It was shown that the strength characteristics of the samples produced from thermoplastics (low density polyethylene, polyamide 6, Armamid, and polyethylene terephthalate) increase as a result of short vibration treating with a frequency close to that of natural vibrations of the structural elements.