石墨炉原子吸收光谱法测定滑石中酸溶痕量铅镉

研究了石墨炉原子吸收光谱法测定滑石中酸溶痕量铅镉的方法。采用硝酸(φ=5%)加热溶解滑石,既表征自然环境中滑石所能溶出的全部铅、镉,又避免了对石墨管的腐蚀,得到平稳且较高的吸光度。利用试样中溶出基体镁与硝酸形成的硝酸镁作为基体改进剂,使铅、镉的灰化温度分别提高到900℃和500℃,消除了基体干扰,溶出滑石中的其他元素均不影响铅、镉的测定。该方法测定铅、镉量的线性范围分别为0~100μg/mL,0~10μg/mL;检出限分别为1.95μg/L,0.54μg/L。用于滑石中酸溶铅、镉的测定,相对标准偏差分别为     

阻抑过氧化氢氧化二甲酚橙褪色动力学光度法测定镉

在pH 9.7的Na2B4O7-NaOH缓冲溶液中,镉对过氧化氢氧化二甲酚橙褪色的反应有阻抑作用,从而建立一种新的测定镉的催化动力学光度法。研究了影响阻抑作用的各种因素,得到最佳测定条件及动力学参数,结果表明,反应产物的最大吸收波长位于580 nm,方法的线性范围为0.6~1.6μg/mL,检出限为0.15μg/mL。大多数共存离子不干扰测定,Co2+,Cu2+,Fe3+,Mn2+等离子的干扰可加入三乙醇胺和β-巯基丙酸消除。催化反应的表观活化能为58.27 kJ/mol。方法用于矿物样品中镉的测定,其标准加入回收率为95%~103%之间,RSD为2.4%~3.0%。     

电感耦合等离子体原子发射光谱法测定精制铝箔中铅镉砷

试样用硝酸、盐酸溶解,用电感耦合等离子体原子发射光谱(ICP-AES)法测定铅、镉;用盐酸、硝酸、硫酸溶解,在盐酸介质中以四氯化碳萃取去除铝,然后用ICP-AES法测定砷。测定时选择283.306 nm,226.502 nm,197.262 nm分别作为铅、镉、砷的分析线,基体铝对铅、镉测定的影响采用基体匹配方法克服。对于5μg/mL的As,Pb,Cd,20倍量的Zn,Si,Mn,V,Ti,Mg无干扰。铅、砷的检出限均为0.01μg/mL,镉的检出限为0.001μg/mL。用本法测定铝箔样品中铅、镉、砷,     

微波加热酸浸提—原子吸收光谱法测定重晶石中铅镉

使用微波消解仪,在密闭升温增压条件下,以王水浸提重晶石中铅和镉,用火焰原子吸收光谱法测定铅,石墨炉原子吸收光谱法测定镉。浸取率比用同样酸的常压敞开浸提法高,样品空白值低;处理样品的速度比用高压坩埚酸浸提法快;试样中的铅和镉损失比碳酸钠融熔处理法少。方法检出限:铅为0.069μg/mL,镉为0.087μg/mL。样品中铅、镉的加标回收率分别为95.1%～99.5%,97.1%～104.4%;相对标准偏差分别为1.3%～3.2%,1.6%～2.8%。     

电感耦合等离子质谱法测定盐中痕量有害元素的研究

采用电感耦合等离子体质谱 (ICP MS)法 ,对盐中痕量铅、镉、砷、铬进行了分析。对影响测定的各种因素进行了较详细的研究 ,确定了测定最佳条件。结果表明 ,方法检出限为 :Pb.0 .0 0 3 μg/L ,Cd 0. 0 0 5 μg/L ,As 0 .0 0 3 μg/L ,Cr 0 .0 0 8μg/L ,回收率为 :90. 8%～ 10 9.5 % ,RSD小于 3.68%。该法准确、快速、简便 ,应用于盐中痕量铅、镉、砷、铬的测定 ,结果满意     

电感耦合等离子体发射光谱法同时测定铅冶炼工作场所空气中的铊砷镉等有害元素

针对铅冶炼工作场所空气中的铊、砷、镉等的含量的快速检测难题,利用升级改造后电感耦合等离子体发射光谱仪,通过使用微孔滤膜收集空气中烟尘,采用高氯酸、硝酸进行消解溶样,配制铊、砷、镉等标准溶液,使用ICP-AES仪器进行铊、砷、镉谱线的选择和干扰校正,能够实现一次溶样,同时完成多种重金属有害元素测定,方法准确快捷,试验研究加标回收率在98%～103%之间,铊、砷、镉的检出限分别达到0.001 5μg/mL、0.002 1μg/m、0.000 1μg/mL等,很好地满足了企业对空气中有害元素快速检测需求。     

铑Ⅲ-水溶性苯胺蓝-溴酸钾体系阻抑动力学光度法测定痕量铑

在磷酸介质中痕量铑Ⅲ对KBrO3氧化水溶性苯胺蓝褪色反应有很强的抑制作用,据此建立了阻抑动力学光度法测定痕量铑Ⅲ的新方法。在选定条件下,方法的线性范围是0.4~0.8 ng/mL,检出限为2.73×10-11g/mL,表观活化能为167.26 kJ/mol。试验了30多种共存离子的影响,大多数的常见离子不干扰。方法用于两个催化剂样品中铑的测定,相对标准偏差(RSD)分别为2.0%和2.3%,加标平均回收率分别为102%和103%(n=6)。     

阻抑动力学光度法测定痕量碘的研究

研究了在稀磷酸介质中,痕量碘离子对亚硝酸根催化溴酸钾氧化亚甲蓝的阻抑作用,建立了测定痕量碘离子的阻抑动力学光度分析新方法。测定碘离子的线性范围为0.040～0.48μg/mL,检出限为1.7×10-8g/mL。用于测定盐中的微量碘,结果满意。     

阻抑罗丹明6G褪色反应动力学光度法测定痕量钛(Ⅳ)

基于稀H2SO4介质中,痕量钛(Ⅳ)阻抑H2O2氧化罗丹明6G(Rh6G)的褪色反应,建立了测定痕量钛(Ⅳ)的催化动力学光度法。讨论了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响。研究了反应的最佳条件,并测定了一些动力学参数,催化反应的表观活化能为57.77 kJ/mol。方法检出限为0.45μg/L,线性范围为0~24.0μg/L。在25 mL溶液中,测定0.6μg钛(Ⅳ)的相对标准偏差为2.10%(n=11)。结合溶剂萃取分离,实现了岩石样品中钛(Ⅳ)的测定,结果与认定值相符,相对标准偏差为     

钒(Ⅴ)-次磷酸钠-偶氮胂Ⅲ体系催化动力学光度法测定痕量钒

基于0.016 mol/L的H2SO4介质中,痕量钒(Ⅴ)对次磷酸钠(NaH2PO2)还原偶氮肿Ⅲ(AsAⅢ)的褪色反应有明显的阻抑作用,建立了测定痕量钒(Ⅳ)的动力学光度法.钒(Ⅴ)质量浓度在0～4.0μg/L范围内服从比尔定律,方法检出限为0.058μg/L.在25 mL溶液中,测定0.1→μg钒(Ⅴ)的相对标准偏差为1.5%(n=11).讨论了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响,研究了反应的最佳条件,并测定了一些动力学参数,催化反应的表观活化能为46.80 kJ/mol.用于测定人发和茶叶样品中痕量钒(Ⅴ),相对标准偏差为3.0%～4.2%,标准加入回收率为98.2%～101.4%.     

Effects of weathering and flue-curing on monocrotophos residues on tobacco

Disappearance of monocrotophos from flue-cured tobacco was studied at three locations (Kinston, Clayton, and Reidsville, North Carolina) in 1973. Average residues on green tobacco leaves collected immediately after application were 41 and 84 ppm, respectively, for application rates of 0.56 and 1.12 kg/ha. Levels declined to about 18 and 40 ppm for the two rates three days after application, to about 9 and 23 ppm at five days, and to about three and eight ppm at nine days. Conventional curing reduced residues on flue-cured tobacco by at least 99%.     

稀土对铜及铜合金组织和性能影响的研究进展

综述了稀土对铜及铜合金组织和性能影响的国内外研究进展情况,主要介绍了稀土在铜及铜合金中的热力学性质,以及稀土对铜及铜合金组织的净化,细化及改变夹杂物的形态与分布的作用和影响,并阐述了稀土对铜及铜合金的加工性能、机械性能、导电性能、抗氧化性能、耐腐蚀性能和耐磨性能等方面的影响.     

Effect of aminophylline on frequency of blood flow in utero-placental and fetal circulation, on arterial blood pressure and on cardiotocography

Aminophylline was given (125 mg i.v.) in 24 cases with fetal hypotrophy. Blood flow was measured (Doppler technique) before aminophylline injection, 30 min. and 3-4 hours after. Blood pressure was monitored continuously, CTG was performed many times before and after administration of aminophylline. After administration of aminophylline diastolic blood pressure decreased during 3-4 hours and blood flow in the arcuate artery increased. There were no changes in the blood flow in the umbilical artery and fetal aorta after administration of aminophylline. We didn't observe any changes in CTG before and after administration of aminophylline.     

屋面卷材空鼓起包的原因分析及防治方法探讨

针对多年来屋面防水工程卷材空鼓起包、拉裂渗透问题,在试验及多年工程实践基础上找出其原因:卷材粘贴不牢,窜入卷材与找平层之间的气体受热膨胀将卷材拱起所致.防治方法主要是:早喷稀冷底子油,增加卷材与找平层的粘结力;设置排气孔,及时将空气排走.这对改善屋面防水工程质量具有-定指导意义.     

Effects of ethinylestradiol on the renin-angiotensin-aldosterone-system and on plasma transcortin in women and men

The effects of ethinylestradiol (1 mug/kg body weight daily) on plasma renin substrate concentration, other factors of the renin-aldosterone-system, and on the cortisol-binding capacity of transcortin were determined in 8 young men and 9 young women. The absolute and relative elevation of plasma renin substrate after 5, 14, and 24 days of ethinylestradiol administration was significantly (P less than 0.001) greater in females than males. Control and posttreatment transcortin levels were also higher in women than men, but the percentage increase did not differ between males and females. It is likely that sex differences in the response of plasma renin substrate to the estrogen are due to differences in hepatic synthesis and/or release of renin substrate. In females, plasma renin activity, angiotensin II concentration, and urinary aldosterone excretion rose significantly although less markedly than plasma renin substrate concentration, while in males only the increase in plasma angiotensin II concentration was significant. These results indicate that no safe conclusions on metabolic effects of estrogen treatment in women can be drawn from experiments carried out in male subjects.     

Effect of silicon and yttrium on the structure and properties of diffusion coatings on nickel alloys

The processes occurring during the formation of combined aluminide coatings on nickel alloys using gas and plasma vacuum technology are considered. It is shown that the external surface of the coating has the structure of a secondary β-NiAl solid solution after the application of a diffusion coating from an Al?Si–Y alloy directly on the surface of alloys or on samples preliminary aluminized or chromoaluminized at 1000°C. The results of heat-resistance tests at temperatures of 1000 and 1050°C are presented.     

Research progress on influence of inclusion on ductility and toughness of steel

The ductility and toughness of steel are inextricably linked with the non metallic inclusions, how to minimize the damage of inclusions on mechanical properties of steel is an important research priority in the metallurgy and materials field. The effects of inclusions on the ductility and toughness of steel were summarized from the perspective of type, size, number, distribution, and physical properties of inclusions. The fracture mechanism of steel caused by inclusion was also discussed. Then, the relationship between inclusion and mechanical properties of steel is prospected, which could provide a theoretical basis and technical reference for control technology of inclusions.     

夹杂物对钢塑性和韧性的影响研究进展

摘要：非金属夹杂物与钢的塑性和韧性有着必然的联系,如何降低夹杂物对钢性能的危害一直是冶金和材料领域关注的重点。从夹杂物类型、尺寸、数量、分布及其物理性能等角度归纳总结了夹杂物对钢塑性和韧性的影响,并分析了夹杂物引起材料断裂的机制。最后,对夹杂物与钢材性能的关系进行了展望,为钢铁企业非金属夹杂物的控制提供理论依据和技术参考。     

基于岩矿鉴定法的地质矿产特征及分布情况分析

在传统的地质矿产特征及分布情况分析中,由于没有结合先进的科学方法,因此无法对地质矿产特征及分布情况精准掌握。针对这一问题,进行基于岩矿鉴定法的地质矿产特征及分布情况分析。首先,基于岩矿鉴定法进行地质矿产特征分析,得出该地区地质矿产特征为东侧地下矿产资源较为丰富;再基于岩矿鉴定法分析地质分布情况,AB段地质分布最为密集;MN段地质分布较为均匀;ZE段地质分布稀疏。应加大AB段找矿力度,致力于推动该地区矿业工作的进一步发展。