用凯氏定氮仪测定蛋白质结果的不确定度评定

本文列出影响用凯氏定氮仪测定蛋白质结果的因子,依据测量不确定度评定规范,尝试对测定蛋白质结果不确定度的评价。     

全自动凯氏定氮仪测定酱油中全氮含量不确定度的评定

本文采用全自动凯式定氮仪测定酱油中全氮含量,对测定过程中的不确定度进行分析和量化,给出各分量对测定结果不确定度的相对贡献,求出测定结果的标准不确定度和扩展不确定度并对结果进行表述。结果表明：由样品重复性试验和移取试样体积引入的不确定度最大,其次是盐酸标准溶液浓度的不确定度。     

凯氏定氮仪测定豆粕中粗蛋白质的不确定度评定

通过对凯氏定氮仪测定豆粕中粗蛋白质含量的检验过程进行分析,确定影响测量不确定度的因素,并对各个不确定度分量进行评定和计算合成,给出该仪器测定豆粕中粗蛋白质的合成不确定度和扩展不确定度,提出减小不确定度的方法。     

凯氏定氮仪原理和校准的方法

0引言凯氏定氮仪被广泛运用于食品、谷物、油料等中粗蛋白质的测定,其测量结果的准确度和可靠性直接影响到对上述产品的质量评价。近来,客户针对此类仪器的校准需求越来越多,而目前国内尚无针对凯氏定氮仪的检定规程或校准规范,     

应用全自动定氮仪测定ABS树脂氮含量的探讨

本文应用Kjeltec2300全自动定氮仪测定硫酸铵,回收率达100.24%,其测定ABS树脂中氮含量与美标D1013-93[1]相比差异不显著,表明全自动定氮仪能简便、快速、准确地分析大批量ABS树脂中的氮含量。     

KDN-04B型定氮仪测定乳粉中蛋白质含量的研究

采用KDN-04B型定氮仪测定乳粉中蛋白质含量,准确度及精密度均较高,与国标法装置比较无显著差异,且具有操作方便,稳定,耗时短,经济适用等特点。     

关于食品中蛋白质测试方法探讨及对KDN-08C型定氮仪的改进

关于食品中蛋白质测定方法探讨及对KDN-08C型定氮仪进行改造,改造后仪器对于食品中蛋白质含量在3%———80%范围内均能获得满意的结果,且操作简便,方法快速、准确。     

浅谈食品中蛋白质含量的测定

本文对于食品中蛋白质的测定方法及实验中的注意事项作了一些总结,以确保食品中蛋白质含量的测定更为准确.     

全自动石墨消解仪测定土壤中Cr、Cu、Pb、Ni、Zn、Hg和As

全自动石墨消解仪可实现消解过程全自动程序化控制,减少人为误差,无须人员值守,处理批量大,一次消解可同时检测多种金属元素,采用全自动石墨消解仪对土壤标准样品GSS-1进行消解,并使用原子吸收仪和原子荧光光度计测定其Cr、Cu、Pb、Ni、Zn、Hg和As含量,重复测定5次的检测结果和平均值都在标准值的允差范围内,且相对标准偏差RSD均小于10%,其中Ni元素的RSD值最高,为5.7%,由此说明,使用全自动石墨消解仪消解土壤标准样品具有较好的准确度和精密度。     

为无线的安全考虑——模块式开放型HMI为危险场合中无线局域网解决方案的应用奠定基础

无线局域网在流程工业企业中的优点非常明显,在安装操作设备和监控设备时省略了电缆布线的工作。但是,它在易燃易爆危险场合中使用时,必须要求其具有防爆网络技术和HMI防爆保护的功能。但满足这些条件就给系统的维护保养带来了一定的困难。而模块式开放型HMI系列操作设备为易燃易爆危险场合中无线局域网的应用提供了良好的操作性能。     

国内外汽车用塑料概况及新的成型方法

概括介绍了国内外汽车用塑料的历史、现状及未来发展趋势。讨论了汽车用塑料的应用、品种和新的成型方法。     

改进测定鱼粉中挥发性盐基氮方法的探讨

本文采用碳酸钾溶液作碱性试剂,并用自动凯氏定氮仪测定鱼粉中的挥发性盐基氮,与国标GB/T5009.44-1996中半微量定氮法比较,两种方法无显著性差异,测定结果令人满意。该方法快速、准确。     

Nondestructive testing of materials using 14 MeV neutrons and a pulse-shape analyzer system

A 14 MeV neutron generator and fast neutron spectrometer consisting of an organic scintillation detector and a pulse-shape analyzer are used for the nondestructive testing of materials. The 14.6 MeV peak (in the 12.7–15.7 MeV region) is observed to change as a function of both the kind of testing material and the defect condition inside the material. The number of neutron counts under the 14.6 MeV peak for lighter testing materials (e.g., plastic, brass, and aluminum) with a defect will increase, as compared to the number of neutron counts under the same peak region of an identical testing material but with no defect. For heavier testing materials (e.g., steel and lead), the inverse is observed. The method is feasible even with defects of size 0.25 cm³ (i.e., a cylindrical cavity 0.4 cm in diameter and 2.0 cm in length), although quantitative evaluation of the size of the defect as a function of the change of the number of neutron counts under the 14.6 MeV peak region is difficult due to instability of the 14 MeV neutron output.     

汽车空调压缩机可控定量加油装置

对汽车空调压缩机冷冻机油的注入进行分析设计，利用呵控装置对油的加入进行控制，做到精确而快速，操作维护方便。     

Mechanical characterization of NiTi SMA wires using a dynamic mechanical analyzer

An investigation into the thermo-mechanical response of trained Ni–Ti shape memory alloy (SMA) wires with two-way shape memory effect (TWSME) induced into them was conducted in order to examine the influence of the cold work on quasi-static and fatigue behavior of SMAs. Use of dynamic mechanical analyzer (DMA) for such tests on thin wires was examined and successfully utilized. Quasi-static stress–strain responses of the wires at different temperatures were obtained to determine the critical stresses for forward as well as reverse transformations. Mechanical stress-controlled fatigue tests were conducted on the wires in the austenitic state (130 °C). They showed a two-stage deterioration of fatigue life—a rapid decay when the maximum stress of the fatigue cycle is higher than the critical transformation stress, and a more gradual deterioration at stress levels considerably lower than the critical stress. The fatigue life of the wires was found to increase with the load ratio, R, whereas the frequency of cyclic loading had only a marginal effect. Differential scanning calorimetry (DSC) of the fatigued austenite specimens indicated the presence of residual stress-induced martensite in the austenitic state. The high concentration of the austenite–martensite interfaces act as potential sites for stress-concentration and are the main source of the drastic decrease of the fatigue life in the two-phase region.     

用动态热机械分析仪研究橡胶的低温动态力学性能

介绍了动态机械热分析仪(DMA)在天然橡胶研究领域中的应用。利用DMA研究了天然橡胶及其改性物的低温动态力学性能,测定了样品的动态力学性能参数,并应用动态力学性能的时温叠加(TTS)原理,由WLF方程的常数C1和C2进一步计算出材料的脆性参数。     

Optimized calibration and measurement procedures in rotating analyzer and rotating polarizer ellipsometry

Accurate spectroellipsometric (SE) measurements in the rotating analyzer (RAE) or rotating polarizer (RPE) configurations require accurate values of the polarizer/analyzer(/retarder) azimuths. While the readings are usually fairly accurate, true values are influenced by possible offsets between the plane of incidence, physical axes of the elements, and the instrument scales. The offsets are often determined by specialized calibration procedures. We describe SE measurements designed to obtain the calibration parameters together with the target ellipsometric spectra. We use multiple settings of the polarizer (analyzer) azimuths in RAE (RPE), respectively, to optimize precision and accuracy of SE measurements, and to economize measurement time. The optimization concerns the choice of measurement parameters as well as the subsequent data analysis. We present in detail examples of visible-ultraviolet measurements.     

汽车覆盖件冲压变形趋向性控制

汽车覆盖件冲压成形过程中的变形是非常复杂的,在进行工艺设计和模具设计时不能用计算的方法得到变形的定量分布,为此,通过对覆盖件特点的分析,提出了对汽车覆盖件冲压成形进行变形趋势分析的方法,以及控制汽车覆盖件冲压变形趋势的措施,并进行了实例分析.     

微量水分析仪在空分设备中的应用与维护

介绍微量水分析仪的工作原理及日常维护经验,结合青岛钢铁气体有限公司空分设备配套微量水分析仪的选用和实际使用情况,阐述空分设备微量水分析仪的选型经验。