Measurement of Mercury in Human Hair

Measurements of total and inorganic mercury in human hair were used to trace the history and extent of methyl mercury exposures. Data on the distribution of mercury in hair were converted by a mathematical model into information about the key indices of exposure, including times of onset and termination, peak concentration in hair, and half-time of retention in blood. The model was used for computer simulations of the true distribution of mercury in hair and was validated by analyses of segments of single hairs. Conventional methods of hair sampling and fitting the resulting data to a curve were shown to introduce systematic errors underestimating peak concentrations and overestimating retention times. These errors were minimized by practical modification of the hair sampling procedures and by a new graphic method for deriving the measurements of distribution of the trace element in hair.     

公共场所集中空调通风系统现场采样释义

近年来,公共场所内的集中空调越来越深受人们的欢迎。其通风系统现场样品采集样是监测工作的前提基础和关键控制点,为提高现场采样工作的效率,确保采集样品具有代表性,根据在现场采样的实际工作遇到的问题,从采样前期准备、现场采集、采样后贮藏等方面对公共场所集中空调通风系统现场采样进行探讨。     

北方高氨氮渗沥液吹脱处理工艺参数的研究

采用单因素试验和正交试验相结合的方式,对吹脱法处理北方某垃圾填埋场渗沥液中的氨氮进行研究,考察了p H、吹脱时间、曝气量及原液浓度对氨氮脱除的影响。结果表明:单因素试验确定的适宜范围为p H11.0~11.5、吹脱时间150~180 min、曝气量5.50~8.25 L/min,而正交试验确定的最优组合为p H11.0、吹脱时间180min、曝气量8.25 L/min。在此条件下,氨氮浓度大大降低,可进入后续生化处理系统进行处理。     

毛细管气相色谱测定室内空气中苯的分析误差评价

目的评价毛细管气相色谱测定室内空气中苯的分析误差。方法采用FFAP毛细管柱和FID检测器,以二硫化碳提取,对空白溶液、0.1c标准溶液、空气样品、加标空气样品中苯进行测定。结果 4种试样的批内批间变异分析(F相似文献   

Exhaled Nitric Oxide: A Novel Biomarker of Adverse Respiratory Health Effects in Epidemiological Studies

The sampling of exhaled breath is a noninvasive procedure that can be performed easily in adults, children, and patients with respiratory disease. Several studies have demonstrated increased exhaled nitric oxide in patients with pulmonary disease, including asthma. In addition, exhaled nitric oxide may be an elegant tool for monitoring of environmental health effects of air pollution and the prevalence of atopy in epidemiological surveys. Recent literature about exhaled nitric oxide is presented in this article. Technical, physiological, and behavioral confounding factors of exhaled nitric oxide measurement are outlined.     

Air pollution‐associated procoagulant changes: the role of circulating microvesicles

Summary. Background: Epidemiological studies suggest an association between exposure to particulate matter (PM) in air pollution and the risk of venous thromboembolism (VTE). Objectives: To investigate the underlying pathophysiological pathways linking PM exposure and VTE. Patients and methods: We assessed potential associations between PM exposure and coagulation and inflammation parameters, including circulating microvesicles, in a group of 233 patients with diabetes. Results: The numbers of circulating blood platelet‐derived and annexin V‐binding microvesicles were inversely associated with the current levels of PM_2.5 or PM₁₀, measured on the day of sampling. Recent past exposure to PM₁₀, up to 1 week prior to blood sampling, estimated at the patients’ residential addresses, was associated with elevated high‐sensitivity C‐reactive protein (CRP), leukocytes and fibrinogen, as well as with tissue factor (TF)‐dependent procoagulant changes in thrombin generation assays. When longer windows of past exposure were considered, up to 1 year preceding blood sampling, procoagulant changes were evident from the strongly increased numbers of red blood cell‐derived circulating microvesicles and annexin V‐binding microvesicles, but they no longer associated with TF. Past PM exposure was never associated with activated partial thromboplastin time (aPTT), prothrombin time (PT), or factor (F) VII, FVIII, FXII or D‐dimers. Residential distance to a major road was only marginally correlated with procoagulant changes in FVIII and thrombin generation. Conclusions: Increases in the number of microvesicles and in their procoagulant properties, rather than increases in coagulation factors per se, seem to contribute to the risk of VTE, developing during prolonged exposure to air pollutants.     

Orthogonal Design on Range Hood with Air Curtain and Its Effects on Kitchen Environment

Conventional range hoods cannot effectively prevent the oil fumes containing cooking-induced harmful material from escaping into the kitchen Air curtains and guide plates have been used in range hoods to reduce the escape of airborne emissions and heat, thereby improving the kitchen environment and the cook's degree of comfort. In this article, numerical simulations are used to study the effects of the jet velocity of an air curtain, the jet angle of the air curtain, the width of the jet slot, the area of the guide plate, and the exhaust rate of the range hood on the perceived temperature, the perceived concentration of oil fumes, the release temperature of oil fumes, and the concentration of escaped oil fumes in a kitchen. The orthogonal experiment results show that the exhaust rate of the range hood is the main factor influencing the fumes concentration and the temperature distribution in the kitchen. For the range hood examined in the present study, the optimum values of the exhaust rate, the jet velocity of the air curtain, the jet angle of the air curtain, the width of the jet slot, and the area of the guide plate are 10.5 m³/min, 1.5 m/s, ?5°, 4 mm, and 0.22 m², respectively, based on the results of the parametric study. In addition, the velocity field, temperature field, and oil fumes concentration field in the kitchen using the proposed range hood with the air curtain and guide plate are analyzed for those parameters. The study's results provide significant information needed for improving the kitchen environment.     

Development,validity and reliability of a new pressure air biofeedback device (PAB) for measuring isometric extension strength of the lumbar spine

This study describes the development of a new portable muscle testing device, using air pressure as a biofeedback and strength testing tool. For this purpose, a pressure air biofeedback device (PAB^®) was developed to measure and record the isometric extension strength of the lumbar multifidus muscle in asymptomatic and low back pain (LBP) persons. A total of 42 subjects (age 47.58 years, ±18.58) participated in this study. The validity of PAB^® was assessed by comparing a selected measure, air pressure force in millibar (mb), to a standard criterion; calibrated weights in kilograms (kg) during day-to-day tests. Furthermore, clinical trial-to-trial and day-to-day tests of maximum voluntary isometric contraction (MVIC) of L5 lumbar multifidus were done to compare air pressure force (mb) to electromyography (EMG) in microvolt (μV) and to measure the reliability of PAB^®. A highly significant relationship were found between air pressure output (mb) and calibrated weights (kg). In addition, Pearson correlation calculations showed a significant relationship between PAB^® force (mb) and EMG activity (μV) for all subjects (n?=?42) examined, as well as for the asymptomatic group (n?=?24). No relationship was detected for the LBP group (n?=?18). In terms of lumbar extension strength, we found that asymptomatic subjects were significantly stronger than LBP subjects. The results of the PAB^® test differentiated between LBP and asymptomatic subject’s lumbar isometric extension strength without any risk to the subjects and also indicate that the lumbar isometric extension test with the new PAB^® device is reliable and valid.