有机物全熔点标准物质定值用毛细管熔点仪的研制

研制一种基于毛细管熔点原理的真空绝热杯式毛细管熔点仪,该装置消除了温场不均匀和温度计热滞后带来的系统误差,具有较高的测量精度.该装置用于月桂酸、联苯、咪唑、乙酰苯胺、非那西丁、对甲基苯甲酸、蒽和咔唑等8种有机物全熔点标准物质的定值,标准物质全熔点扩展不确定度为0.20℃和0.17℃(升温速率分别为1.0℃/min和0.5℃/min).标准物质定值结果与改进后的差示扫描量热仪结果一致,两者之间的差别不大于0.23℃,从而验证了该装置的准确性.     

数字温度计不能代替熔点标物用于毛细管熔点仪检定的原因

熔点仪是生产药物、香料、染料及其他有机晶体物质的必备仪器。熔点仪分为毛细管熔点仪和热台熔点仪,本文讨论的熔点仪指毛细管熔点仪（以下简称＂熔点仪＂）。熔点仪主要由加热、控温和测温等部分组成。在检定熔点仪时,利用熔点标准物质（以下简称＂熔点标物＂）作为实物量具,检测熔点仪温度示值的准确性。     

毛细管熔点标准物质的定值

本文介绍了采用绝对测量法测量毛细管熔点标准物质熔点的方法、均匀性检验结果、定值结果及不确定度的估计。     

梅特勒-托利多超越系列熔点仪全新上市——熔点仪新概念：自动测量与视频记录同步

瑞士梅特勒-托利多于2009年4月推出称为“超越”系列的全新毛细管熔点仪MP50、MP70和MP90。超越系列熔点仪带来了熔点测定新概念：自动测量与视频记录同步。     

熔点测定仪示值误差测量结果不确定度评定

<正>一、概述1.依据JJG701-2008《熔点测定仪》检定规程。2.标准器国家标准物质。3.检定对象熔点仪。     

熔点测定仪测量能力(CMC)的评估

1概述(1)测量依据:JJG 701—2008《熔点测定仪检定规程》(2)计量标准:熔点标准物质(3)被测对象:0.2、0.5、1.0、1.5级熔点测定仪(4)测量原理:毛细管法熔点测定仪是在传温介质中加热毛细管中的试样,观察其相变过程或相变时透光率的变化以确定熔点。热台法熔点测定仪是在热台上加热载玻片和盖玻片之间的试样,通过带有偏光     

熔点测定仪CMC评估

<正>一、概述1.测量依据JJG701-2008《熔点测定仪》检定规程。2.环境条件温度:(23±5)℃,校准时室温波动不大于±2℃;相对湿度:≤85%。3.测量标准国家计量行政部门批准颁布的一级熔点有证标准物质。标准证书的技术指标如表1所示。4.被测对象0.2级、0.5级、1.0级、1.5级熔点测定仪。5.测量方法毛细管法熔点测定仪:将熔点标准物质装入毛细管,放入仪器后进行毛细管法熔点测量。热台法熔点测定仪:将适量的熔点标准物质放于载玻片上,用盖玻片研压晶粒,使其形成单层晶粒的     

毛细管法熔点测定仪示值误差测量结果的不确定度评定

文章主要对毛细管法熔点测定仪示值误差测量结果的不确定度评定进行分析.     

一种新的更为简单的制作镓熔点容器的方法

本文介绍了一种新的更为简单、方便的制作镓熔点容器的方法.该方法利用压力平衡的原理,精确控制所充入气体的压强.并将新方法制作的镓熔点容器与国家基准的镓熔点容器进行比对.     

表面活性剂对相反转法制备金属颗粒的影响

采用相反转悬浮液体系中不同表面活性剂同步修饰的方法制备超细低熔点金属颗粒,研究阳离子和阴离子表面活性剂对金属颗粒的影响。通过沉降实验观察不同表面活性剂修饰的金属颗粒在水中的分散及稳定性,并采用激光粒度仪、扫描电镜对低熔点金属颗粒的粒径和形貌进行表征分析。结果表明:表面活性剂的种类对制备低熔点金属颗粒有重要的影响,其中阴离子表面活性剂的效果最好。对几种阴离子表面活性剂的研究表明:油酸钠的作用最明显,其浓度大小对低熔点金属颗粒的粒径、形貌和分散效果有显著的作用。采用质量分数为1%的油酸钠水溶液可制备出分散稳定、粒径分布窄和球状的超细低熔点金属颗粒,平均粒径为0.343μm。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

卧式金属罐容量的测量结果不确定度

本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。     

盐酸浓度不确定度的评估

通过对盐酸浓度标定的过程分析，找出影响结果的各个分量，进行不确定度的评定，按照计量技术规范给出标准的表示法。     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of anisotropy of properties on the basis of studies of texture of coarse-grained ingots of thermoelectric materials

An analysis of anisotropy of the properties of a Bi₂Se_0.3Te_2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied.