催化动力学光度法测定水中痕量锰

催化动力学光度法测定水中痕量锰,已有许多文章发表（1-2],但以高碘酸钾氧化亮蓝作为指示反应的方法还未见报道。本文系统研究发现,在HAc-NaAc介质中,锰能强烈催化高碘酸钾氧化食用色素亮蓝的褪色反应,波长630nm处,其反应速度Log（Ao/A）与锰的浓度之间符合动力学一级反应关系式:Log（Ao/A）=KCMn,由此建立了一个高灵敏、高选择性的测定痕量锰的新方法。该法最低检出限为8×10-9g/L,线性范围在0-2μg?25ml。用于水样中的痕量锰的测定,结果令人满意。1 实验部分1.1 仪器与试剂　753B型分光光度计（上海分析仪器厂）;电热恒温水浴锅;PHS-3C酸度计（上海精密科学仪器有限公司）;锰标准溶液:1.0mg/ml,使用时稀释成1.0μg/ml;高碘酸钾溶液:0.01mol/L;pH5.5的HAc-NaAc缓冲溶液:用0.2mol/L的HAc     

碱性品红-溴酸钾体系催化动力学光度法测定痕量钒

目的:建立催化动力学光度法测定痕量钒的新方法。方法:在柠檬酸介质中,利用钒对溴酸钾氧化碱性品红的催化作用,在536 nm处测量催化体系和非催化体系的吸光度的变化,用催化光度法测定痕量钒。结果:测定钒的线性范围:0.00100~0.0250μg/ml,检出限为5.7×10-11g/ml。结论:该法简单,灵敏度高,选择性好,可用于食品中痕量钒的测定。     

催化动力学光度法测定植物中的痕量硒(Ⅳ)

在酸性介质和三乙醇胺存在下，硒(Ⅳ)能催化硫化钠氧化亚甲基兰褪色。研究了这一催化反应的动力学条件，建立了利用动力学光度法测定硒(Ⅳ)的新方法。该方法的检测限为3.74×10-7g/L，硒的含量在0～50μg/50ml范围内与褪色反应的A0—A呈线性关系。该方法具有良好的选择性和准确度，用于植物中痕量硒(Ⅳ)的测定，结果满意。     

催化动力学光度法测定水中痕量铋的研究

本文研究了在P^H4．6的NaAc-HAc介质中，痕量铋（Ⅲ）催化H2O2氧化邻苯二酚紫褪色，建立了催化动力学光度法测定痕量铋（1id的新方法。方法的线性范围为0-12．5μg／50ml，检出限为8．2x1O^11g／L。用于水中痕量铋（Ⅲ）的测定，结果满意。     

催化动力学分光光度法间接测定痕量硫离子的研究

目的:建立间接测定痕量硫离子的催化动力学光度分析的新方法。方法:在pH 10.0的NH3.H2O-NH4C l缓冲溶液介质中,利用硫离子对Cu(Ⅱ)催化过氧化氢氧化吖啶黄的阻抑作用,用催化动力学光度法间接测定痕量硫离子。结果:测定硫离子的线性范围为0.010~2.0μg/25 m l,检出限为4.4×10-9g/m l。对1.0μg/25 m l进行10次平行测定的相对标准偏差为2.6%。结论:该法简单、灵敏度高、选择性好,可用于废水中痕量硫离子的测定。     

小麦粉中吊白块检测方法的研究

目的研究催化动力学光度法测定小麦粉中吊白块的方法。方法在硫酸介质中,甲醛可灵敏地催化溴酸钾氧化中性红的退色反应。选择研究了该催化反应中多项测定条伴,参照建立了催化动力学光度法测定痕量甲醛的方法,又对产生假阳性问题的多个干扰因素进行了研究。结果甲醛含量的检测范围为(0.20~1.0)μg/25 ml;该方法的检出限为0.0400μg/25 ml,标准偏差4.45%,加标回收率为91.3%。结论催化动力学光度法测定小麦粉中痕量甲醛的方法是可行的。     

催化动力学光度法测定水中痕量铬(Ⅵ)

目的:建立了催化动力学光度法测定水样中痕量Cr(Ⅵ)的新方法。方法:在硫酸介质中,痕量Cr(Ⅵ)催化过硫酸铵氧化邻甲氧基酚显色,其化合物的最大吸收波长为513nm。结果:方法的线性范围为01016～116μg/25ml Cr(Ⅵ),检出限为5142×10-10g/ml Cr(Ⅵ),相对标准偏差(RSD)<3.27%,样品加标回收率为9716%～10111%。结论:该法用于环境水样中微量铬含量的测定快速、准确、简便。     

双波长双指示剂催化动力学光度法测定痕量锰

目的:建立了测定痕量锰的双波长双指示剂催化动力学光度分析的新方法。方法:在醋酸和醋酸钠介质中,利用锰催化高碘酸钾氧化亮绿和二甲基黄褪色的指示反应,通过测量430 nm和640 nm下,催化体系和非催化体系吸光度的变化,用双波长双指示剂催化动力学光度法测定痕量锰。结果:线性范围为0.15~2.2μg/25 ml,检出限为1.24×10-4μg/25 ml。结论:本方法灵敏度高,体系稳定,具有较好的选择性,可用于面粉和大米中锰的测定。     

溴酸钾-罗丹明B体系催化动力学测定抗癌中草药中痕量硒

研究了硝酸介质中痕量硒 ( )催化溴酸钾氧化罗丹明 B的褪色反应及动力学条件 ,建立了动力学光度法测定痕量硒 ( )的新方法 ,其灵敏度为 0 .90 5μg/L,测定范围 0～ 9.6μg/L,用于测定抗癌中草药中的硒 ( ) ,获得了满意的结果     

双波长催化光度法测定水和人发中痕量铁

目的:建立用双波长催化动力学光度法测定痕量铁的新方法。方法:在硫酸介质中,利用铁催化过氧化氢氧化甲基蓝和茜素红褪色反应,分别在390 nm和610 nm处测量催化体系和非催化体系的吸光度的变化,用双波长催化光度法测定痕量铁离子。结果:测定铁离子的线性范围:0.050~1.20μg/25 m l,检测限:3.2×10-11g/m l。结论:该法简单,灵敏度高,选择性好,可用于水和人发中痕量铁的测定。     

Calcium intake in the elderly: validation of a dietary questionnaire

Epidemiological studies of calcium and osteoporosis have been hampered by the lack of a suitable tool for assessing calcium intake. This report describes a new frequency and amount questionnaire for measuring present and past calcium intake in the elderly. The validity of the questionnaire was tested against two commonly used standards of dietary assessment, five-day duplicate diets and seven-day weighed dietary inventories. The resulting correlation coefficients were, respectively, r = 0.76 and r = 0.69, while that for repeatability was r = 0.84. Furthermore, the questionnaire categorized subjects into thirds of the distribution of intake with almost no gross misclassification. It is suggested that the present findings may be extended to the majority of normal, healthy elderly subjects, implying wide application for the questionnaire in the assessment of calcium intake in the elderly.     

The occurrence of antimicrobial substances in toilet,sink and shower drainpipes of clinical units: A neglected source of antibiotic residues

Antibiotics represent one of the most important drug groups used in the management of bacterial infections in humans and animals. Due to the increasing problem of antibiotic resistance, assurance of the antibacterial effectiveness of these substances has moved into the focus of public health. The reduction in antibiotic residues in wastewater and the environment may play a decisive role in the development of increasing rates of antibiotic resistance. The present study examines the wastewater of 31 patient rooms of various German clinics for possible residues of antibiotics, as well as the wastewater of five private households as a reference.To the best of our knowledge, this study shows for the first time that in hospitals with high antibiotic consumption rates, residues of these drugs can be regularly detected in toilets, sink siphons and shower drains at concentrations ranging from 0.02?μg·L^?1 to a maximum of 79?mg·L^?1. After complete flushing of the wastewater siphons, antibiotics are no longer detectable, but after temporal stagnation, the concentration of the active substances in the water phases of respective siphons increases again, suggesting that antibiotics persist through the washing process in biofilms. This study demonstrates that clinical wastewater systems offer further possibilities for the optimization of antibiotic resistance surveillance.     

Self-reported health problems among Swedish miners one year after unemployment

Unemployment is considered to be a public health concern sincedeterioration in the health of the unemployed is often anticipated.However, for some groups, such as miners, unemployment mightimprove health due to a cessation of potentially harmful occupationalexposures. This study evaluates the health of 79 miners in oneSwedish iron-ore mine, and 226 age-matched controls from thegeneral population, during one year after the closure of themine. The participants received a questionnaire regarding medicalhistory and subjective symptoms at the beginning of the studyperiod, and after one year. Statistically significant negativeeffects on self-reported health attributable to unemploymentwere not found, although neuropsychiatric symptoms were morecommon among the unemployed miners. The miners reported a statisticallysignificant improvement in grip force (p=0.031). They had asignificantly higher prevalence of symptoms associated withmining related exposures when compared with the population controls;pain in the upper extremities [relative risk (RR)=2.27, 95%confidence interval (Cl)=1.44–3.59), back pain (RR=1.84;Cl=1.237–2.75), vasospastic disease of the fingers (RR=2.05;Cl=1.18–3.57) and obstructive respiratory symptoms (attacksof dyspnea and wheezing: RR=3.67; Cl=1.167–11.6).     

Excès de cas humains et animaux de tularémie en France au cours de l’hiver 2007–2008 : émergence ou phénomène isolé ?

Context

Tularemia is a zoonosis affecting humans and hares in France. We describe the results of surveillance in both species, in 2007 and 2008.

Methods

Human tularemia cases are mandatorily notifiable in France since 2003. In hares, surveillance relies on volunteer hunter associations in all districts of the country. Data from mandatory reports and volunteer surveillance in 2007/2008 were analyzed and compared with previous results.

Results

In 2007/2008, 144 cases were reported in humans and 117 cases in hares. This was a 100% increase compared to previous years. Human cases differed from those of previous years only by the frequency of contact with breeding animals. Human cases without any documented risk exposure were also more frequent.

Conclusion

An increase of tularemia cases occurred in 2007/2008 in both species. Complementary studies are needed to identify the species reservoir in France to understand the causes of this peak of cases.     

Occupational health hazards in mining: an overview

This review article outlines the physical, chemical, biological, ergonomic and psychosocial occupational health hazards of mining and associated metallurgical processes. Mining remains an important industrial sector in many parts of the world and although substantial progress has been made in the control of occupational health hazards, there remains room for further risk reduction. This applies particularly to traumatic injury hazards, ergonomic hazards and noise. Vigilance is also required to ensure exposures to coal dust and crystalline silica remain effectively controlled.     

Manufacture and use of nanomaterials: current status in the UK and global trends

This paper provides an overview of the production and use of nanomaterials (NMs), particularly in the UK. Currently, relatively few companies in the UK are identifiable as NM manufacturers, the main emphasis being the bulk markets in metals and metal oxides, and some niche markets such as carbon nanotubes and quantum dots. NM manufacturing in the UK does not reflect the global emphasis on fullerenes, nanotubes and fibres. Some assumptions have been made about the types of NM that are likely to be imported into the UK, which currently include fullerenes, modified fullerenes and other carbon-based NMs including nanotubes. Many university departments, spin-offs and private companies have developed processes for the manufacture of NMs but may only be producing small quantities for research and development (R&D) purposes. However, some have the potential to scale up to produce large quantities. The nanotechnology industry in the UK has strong R&D backup from universities and related institutions. This review has covered R&D trends at such institutions, and appropriate information has been added to a searchable database. While several companies are including NMs in their products, only a few (e.g. manufacturers of paints, coatings, cosmetics, catalysts, polymer composites) are using nanoparticles (NPs) in any significant quantities. However, this situation is likely to change rapidly. There is a need to collect more information about exposure to NPs in both manufacturing and user scenarios. As the market grows, and as manufacturers switch from the micro- to the nanoscale, the potential for exposure will increase. More research is required to quantify any risks to workers and consumers.     

深圳公立医院管理体制改革制度设计

深圳公立医院管理体制改革实行政事分开、管办分开,在理事会架构下按法定机构模式组建市医管中心,落实公立医院运营管理自主权.作者从当前公立医院管理体制的弊端入手,介绍了深圳市进行公立医院管理体制改革的基本思路及改革方案设计的主要举措,深入剖析了的改革方案的特点,并对改革效果进行了预测.     

Effects of nitrogen dioxide on red blood cells of rats: Changes in components of red cell membranes during in vivo exposure to NO2

Red cell membranes, prepared from red blood cells of rats exposed to 4, 10, or 20 ppm nitrogen dioxide (NO₂) for 1 to 10 days, were examined for evidence of changes in membrane components. Appreciable changes were not found in contents of phospholipid and cholesterol during exposure to 10 ppm NO₂. By contrast, protein content altered with the time of exposure. Moreover, changes in protein composition were observed by employing sodium dodecyl sulfate — polyacrylamide gel electrophoresis. Twenty-four-hour exposure to NO₂ at the concentration above 10 ppm resulted in a marked increase in the percentage of lysophosphatidylethanolamine (LysoPE) to the total phospholipids. The prolonged exposure to 10 ppm NO₂ gave rise to a further increase in LysoPE, whereas the percentage of phosphatidylethanolamine (PE) showed a gradual decrease. A 1-day exposure to 4.0 ppm NO₂ also caused an increase in sialic acid content and decreases in those of PE and hexose. In addition to contents of these components the percentage of LysoPE increased 5 days after exposure and the elevated values were maintained up to the end of exposure period. These results demonstrate that red blood cells in circulation exhibit different membrane properties in terms of lipid and carbohydrate composition during 10 days of exposure to 4.0 ppm NO₂.     

Investigating clusters in the workplace and beyond

Clusters of disease are common and occur in the workplace and in the general community. They often arouse considerable concern among the population. Investigations have sometimes lead to exciting new knowledge, but in general the investigation of clusters is difficult and often unrewarding, especially for community clusters. In the workplace, investigations are more likely to find associations and even new causes, but still many clusters remain enigmatic. Despite this, there are many reasons for investigating clusters, including allaying community concern and identifying uncontrolled exposures. A structure for investigating clusters in the workplace is suggested.