食品添加剂二氧化碳中氧标准物质重量制备方法及重量制备不确定度的研究

研究了食品添加剂二氧化碳中氧标准物质重量制备的实验方法及不确定度评价研究的内容.采用中国计量科学研究院设计加工的气体充填装置制备了二氧化碳中氧标准物质,该装置低压系统真空度达到7×10-3Pa;气体称量装置采用美国Mettler SB16001电子天平(16 kg、0.1 g)和上海第二天平仪器厂TG320B高精密天平...     

食品添加剂二氧化碳中苯气体标准物质性能评价方法的研究

介绍了食品添加剂二氧化碳中苯气体标准物质的分析方法和性能评价方法。采用美国Agilent6890N气相色谱仪、FID检测器,在最佳色谱实验条件下对苯的检测限小于10×10^-9,线性误差小于2%。还给出了二氧化碳中苯气体标准物质均匀性、一致性、稳定性（随时间、压力变化）的考察结果。研究成果表明二氧化碳中苯气体标准物质重量配制的相对扩展不确定度小于1.7%。     

注射重量法制备气体标准物质中液体称量的数学模型和不确定度评价

由于操作简便和易于读数等优点,电子天平在气体标准物质制备过程中正逐步取代机械天平,成为称量的主要手段。根据ISO 6142中有关对气体称量的数学模型和不确定度的评价,建立了注射重量法制备气体标准物质中使用电子天平称量液体的数学模型,并对称量过程的不确定度进行了评价。     

环境监测用空气中二氧化碳标准气体的研制

介绍了环境监测用空气中二氧化碳标准气体的制备方法。该标准气体的均匀性和稳定性通过气相色谱法进行了考察,并用比对误差确认了其称量法配制值的准确性。配制的标准气体的浓度为（10～1000）×10^-6（mol／mol）,定值不确定度小于2％。     

空气中环戊烷气体标准物质的研制

称量法制备空气中环戊烷气体标准物质,采用气相色谱法进行均匀性、稳定性考察及比对分析,确保数值准确可靠。空气中环戊烷的浓度范围为（0．1—1．0）×10^-2（mol／mol）。     

渗透压摩尔浓度标准物质的不确定度评定

本文通过对天平称量、最小二乘法回归公式、标准物质均匀性及稳定性检验等各不确定度分量的分析,简单评定了重量法制备系列渗透压摩尔浓度国家有证标准物质的不确定度评定.     

生乳冰点标准溶液系列的配制及不确定度分析

本文通过对天平称量、最小二乘法回归公式、标准物质均匀性及稳定性检验等各不确定度分量的分析,评定了重量法制备系列生乳冰点标准溶液的不确定度。     

甲烷中微量气体标准物质分析方法研究及量值的比对（续二）

建立了甲烷中微量气体标准物质的分析方法和实验条件;考察了该分析方法的不确定度;得出甲烷中微量气体标准物质浓度在（1～50）×10-6（mol/mol）范围内,方法不确定度小于1%的实验结果。实验过程对重量法制备的系列气体标准物质量值进行了分析方法的比对,一致性验证结果在1%内吻合。该项研究成果代表国家最高实验室参与了国际计量委员会组织的CCQM-K66的关键比对,得到了满意的实验结果,获得了国际的等效度。     

称量法制备气体标准物质的称量相对标准不确定度评定方法研究

结合国际称量法制备气体标准物质的标准ISO 6142,提出以质量比较仪为称量工具,制备二元混合气体标准物质和多元混合气体标准物质的称量相对标准不确定度的评定方式。并以称量法制备10μmol/mol氮中一氧化氮气体标准物质为例,比较两种方式的评定结果,表明所提出的两种不确定评定方式比国际标准ISO 6142中使用机械天平的称量相对标准不确定评定方式更为简便。     

二氧化碳中微量氧硫化碳标准气体的稳定性

主要讨论了影响二氧化碳中微量氧硫化碳标准混合气的稳定性因素。实验数据表明影响二氧化碳中微量氧硫化碳标准物质贮藏期限的主要因素是材料的选择和气瓶的处理。选择合适的材质和气瓶处理过程,浓度范围为（100-200）×10^-9（mol／m01）氧硫化碳标准混合气至少可以存放12个月。     

A new,accurate single-sinker densitometer for temperatures from 233 to 523 K at pressures up to 30 MPa

A new apparatus for density measurements of fluids in the entire range from gas to liquid densities is presented. The instrument is a single-sinker buoyancy densitometer designed in a completely new way. The buoyancy force exerted by the sample fluid on an immersed sinker (buoy) is transferred by a new type of magnetic suspension coupling to an analytical balance. In order to reduce drastically the linearity error of the (commercial) balance. a special basic load compensation is applied which also avoids any buoyancy ellèct of the laboratory air on the balance. The new single-sinker densitometer covers a density range from 10 to 200(1 kg - m ' at temperatures from 233 to 523 K and pressures up to 30 MPa. A special compact version of such a single-sinker densitometer can even he used at temperatures from 80 to 523 K at pressures up to 100 MPa. Test measurements on densities of carbon dioxide at 233, 360, and 523 K at pressures up to 30 MPa show that the estimated total uncertainty of ±0.02% to ±0.03% in density is clearly met.Invited paper presented at the Twellth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado. U.S.A.Author to whom correspondence should be addressed.     

Influence of sputtering parameters and nitrogen on the microstructure of chromium nitride thin films deposited on steel substrate by direct-current reactive magnetron sputtering

Chromium nitride thin films were deposited on SA-304 stainless steel substrates by using direct-current reactive magnetron sputtering. The influence of process conditions such as nitrogen content in the fed gas, substrate temperature, and different sputtering gases on microstructural characteristics of the films was investigated. The films showed (200) preferred orientation at low nitrogen content (< 30%) in the fed gas. The formation of Cr₂N and CrN phases was observed when 30% and 40% N₂ were used, with a balance of Ar, respectively. Field emission scanning electron microscopy and atomic force microscopy were used to characterize the morphology and surface topography of the thin films, respectively. Microhardness tests showed a maximum hardness of 16.95 GPa for the 30% nitrogen content.     

液晶显示器外壳生产线平衡分析与改善

液晶显示器外壳生产线平衡分析与改善 针对苏州一个公司的液晶显示器外壳生产线平衡率不高的问题,通过程序分析,综合运用5W1H提问技术、ECRS原则等方法和工具,对其液晶显示器外壳生产线流程进行重新设计。结果表明,改善方案在等待时间、搬运时间和距离等方面有明显的改进。针对原流程中的瓶颈作业,通过运用Flexsim仿真软件进行分析,对比改进前和改进后各工位的作业时间、空闲时间及阻塞率等,讨论新方案的实施效果。最后对整个生产线改进效果进行预测,并对该公司液晶显示器外壳生产线改进提出实施建议。     

Effects of geometry and position of the metal delivery tube on ultrasonic gas atomization

The effects of the geometry and the position of the metal delivery tube on the pressure condition in the gas-metal interaction zone were studied. The measurements were performed under conditions which simulated ultrasonic gas atomization experiments, but at low gas atomization pressures (50–200 psig, 345–1380 kPa). Low gas atomization pressures are used in spray atomization and deposition processes such as liquid dynamic compaction (LDC), and Osprey. Depending on the experimental conditions, either underpressure or overpressure in the metal delivery tube was detected. The magnitude of the underpressures and overpressures was found to increase with the gas atomization pressure; the maximum pressure differences with respect to the atomization tank pressure were about 3 psi (21 kPa) when argon was used as an atomization gas with a pressure of 200 psig (1380 kPa). Underpressure or overpressure effects of such magnitude have a large effect on the metal flow rate during gas atomization. The large pressure differences measured in the present work result from using an atomizer with gas jet diameters larger than those used in previous investigations. Using a large ultrasonic atomizer, argon gas flow rates of about 5 kg/min can be obtained for atomization pressures of 200 psig (1380 kPa).     

C/C复合材料飞机刹车盘的结构与性能

采用企业、行业及国家相关标准的试验方法，对超码复合材料公司，英国Dunlop公司，法国CarbonIn-dusty公司，美国B．F．Goodrich、ALS公司等生产的9种C／C复合材料飞机刹车盘的物理、力学、热学、摩擦磨损的性能特征，以及中南大学生产的C／C复合材料刹车盘的有关性能，进行了对比分析。结果表明，选择适宜的炭纤维预制体结构，控制热解炭基体微观结构为光学粗糙层结构，合理的热处理温度是获得高性能炭刹车盘材料的关键。我国拥有自主知识产权研发的大型民机炭刹车盘在高摩擦特性方面获得了重大突破，已用于波音757—200型飞机，实现了国内C／C复合材料具有里程碑意义的第四个重大突破。     

The functional TiO2-biodegradable plastic composite material produced by HVOF spraying process

Photocatalytic TiO2 coatings on bio-degradable plastic(polybutylene succinate: PBS) were prepared by HVOF spraying using three kinds of agglomerated powders (P200: 200 nm, P30: 30 nm, P7: 7 nm). The microstructures of the coatings were characterized with SEM and XRD analysis, and the photocatalytic efficiency of the coatings was evaluated by photo degradation of gaseous acetaldehyde. For both the HVOF sprayed P200 and P30 coatings, high anatase ratio of 100% was achieved, regardless of the fuel gas pressure. On the other hand, for the HVOF sprayed P7 coating, the anatase ratio decreased from 100% to 49.1% with increasing fuel gas pressure. This decrease may be attributed to the much higher susceptibility to heat of the 7 nm agglomerated powders than the 30 nm and 200 nm agglomerated powders. In terms of the photocatalytic efficiency, HVOF sprayed P200 and P30 coatings seemed to outperform the P7 coatings because of their higher anatase ratios. However, the HVOF sprayed P7 coatings did not show photocatalytic activity possibly because of the extremely small reaction surface area to the photo-catalytic activity and low anatase ratio. Therefore, the present study found that functional PBS plastic with photocatalytic performance could be produced by spraying of ceramics such as TiO2.     

Effects of Gastrointestinal Administration of Human Insulin and a Human Insulin-Deae-Dextran Complex Entrapped in Different Compound Liposomes on Blood Glucose in Rats

The effects of gastrointestinal administration (oral, in duodenum and colon) of human insulin and a human insulin-DEAE (diethylaminoethyl) dextran complex entrapped in different compound liposomes in comparing to human insulin alone given subcutaneously on blood glucose level of normal and STZ-diabetic rats were investigated. The liposomes were prepared from a hydrogenated soy lecithin (Epikuron, E 200 H) and by a high pressure homogenization procedure. Samples were lyophilized and reconstituted in 0.067 M phosphate buffer, pH 7.4 before application. The complexed insulin (0.25 and 0.5 IU/kg insulin) showed no diffrences in blood glucose lowering profiles from the free insulin when both were administered intravenously in normal rats. When given orally, the complex (30 and 60 IU/kg Insulin) entrapped in positive liposomes (E 200 H/cholesterol/stearylamine = 7:2:1, in a molar ratio) indicated no effects in STZ rats. However, this complex liposome (6.0 IU/kg insulin) gave a retention effect of blood glucose lowering as % initial level of about 12% after 5 hours when injected in duodenum and showed two maximum effects of 21 and 22% at 100 and 300 minutes respectively when administered in colon of normal rats. When the free insulin entrapped in positive liposomes was given in duodenum In normal rats, the maximum effect of blood glucose lowering of 10% was observed at 2 hours (6 IU/kg insulin) and 1 hour (12 IU/kg insulin). For the free insulin (12 IU/kg) entrapped in other liposome systems given in duodenum of normal rats, both negative (E 200 H/cholesterol/dlcetyl phosphate=7:2:1, in a molar ratio) and neutral (E 200 H/cholesterol=1:1, in a molar ratio) liposomes indicated the maximum effect of about 30% at 120 minutes. Both cholesterol rich positive (E 200 H/cholesterol/stearylamlne=7:7:1, in a molar ratio) and negative (E 200 H/cholesterol/dicetyl phosphate=7:7:1, in a molar ratio) liposomes showed not only a maximum effect of about 20% at 2 hours, but also a retention of glucose lowering of 20% after 7 hours as well. This study suggested that a development of human Insulin by complexlng with the DEAE-dextran polymer and/or entrapping in liposomes, as a drug delivery system in duodenum and colon, is possible.     

Effect of hydrogen on the electrical properties of CdTe thin films

Polycrystalllne films of CdTe grown by resistive heating technique were exposed to hydrogen gas at high pressures (200–500 PSI). D. c. conductivity studies were made on the hydrogen exposed films. The overall d. c. conductivity decreases with the increase of gas pressure. Decrease in the conductivity is attributed to the decrease in free carrier concentration with increase in gas pressure. X-ray diffraction and optical transmission studies were made on the films and there is a shift in the absorption edge towards longer wave lengths as the pressure of the gas increases.     

丙烯热解炭过程的气相产物分析和动力学研究(英文)

以丙烯为碳源,在700℃～1200℃进行化学气相沉积热解炭。采用气相色谱和质谱联用对反应过程中的气体产物进行定性和半定量分析,采用磁悬浮天平实时称量反应过程中的固相产物进行动力学研究,在此基础上提出丙烯分解形成热解炭的机理。气相产物的分析结果表明:丙烯热解过程产生30多种芳香化合物,随着温度的升高,主要反应生成物由萘转变为苯;动力学研究结果表明,800℃～1000℃的活化能为137±25kJ/mol,生成乙炔的基元反应控制固相产物的形成。当温度高于1000℃时,沉积行为由气相分子通过边界向固相表面扩散和气相成核共同控制,形成热解炭的主要物质逐渐由苯转变为不饱和碳氢化合物如乙烃,乙烯等。