Theory of passive measurement of radon daughters and working levels by the nuclear track technique

A theoretical basis is described for long-term measurement of the activities of the alpha emitters in air by the track-etching technique. Inference of the other activities allows working levels to be derived. A set of absorber foils allows the differing response to alpha particles of different energies to be used to identify the relative abundance of the alpha emitters and the importance of diffusion to surfaces. The method is appropriate to measuring long-term exposures to radon atmospheres in homes or mines.     

Passive measurement of working levels and effective diffusion constants of radon daughters by the nuclear track technique

Measurements were made of working level ratios and the effective diffusion constants of radon daughters using a special housing designed to provide a uniform diffusional environment at the passive detectors. For 2 of 7 exposures, the measured scale of the diffusion was too large to satisfy the uniformity requirement. For the other 5, it was satisfied and reasonable working level ratios (WLR) were obtained. Such a housing could be used for extended area working level measurements but is too bulky to be suitable for personnel dosimetry. Personnel dosimetry could be done in mines using a passive area measurement of WLR combined with individual passive 222Rn measurements.     

Calculating the calibration coefficient for radon measurements with the bare LR 115-II track detector.

Model calculations were performed to determine the calibration coefficient for radon measurements using a bare LR 115-II track detector. Calculations were based on an expression for stopping power for heavily charged particles, as well as on the Monte Carlo method. The sensitivity of the LR 115-II detector depends on equilibrium factor F, and it has been calculated for various values of F. For equilibrium factor F = 1, the calibration coefficient in this calculation was 89 m-1 (10.3 Bq d m-3 per tracks cm-2) for the removed layer, which was 5.5 microns thick.     

Indoor 222Rn measurements in Sweden with the solid-state nuclear track detector technique

Measurements of the indoor radon and radon daughter concentrations were performed in several thousand Swedish houses during the years 1979-1984 with the solid state nuclear track detector technique (SSNTD technique). The investigation focused on structures containing building materials of light-weight concrete with enhanced amounts of U. The detectors used nuclear track films exposed for 1 mo. The film basically measures total airborne alpha activity but may be calibrated in units of EER in an environment with known 222Rn and daughter concentrations. (EER is here the equilibrium equivalent concentration of Rn with the equilibrium factor F = 0.5.) The investigation was performed in various municipalities in collaboration with the local public health and environmental authorities. The investigation included 6700 individual measurements in detached (single-family) houses as well as in apartment houses. A small percentage of the dwellings exhibited Rn daughter concentrations (EER) exceeding 400 Bq m-3. It was found in detached houses that the concentrations were higher in the basement floor than in the entrance floor of a house. The Rn daughter values in the bedrooms were similar to values in any other room (mainly on the same floor) of the structure. The Rn daughter levels in apartment houses were lower than in single-family houses. The seasonal variations of the Rn daughter levels are presented and show that the levels in summertime are approximately equal to the levels in the winter.     

Measurement of the effective dose equivalent in a nuclear reactor environment with a personal thermoluminescent dosimeter

A study was performed on the measurement of the effective dose equivalent (EDE) with a personal thermoluminescent dosimeter. A Rando phantom with dosimeters inserted at the sites of the tissues specified by ICRP Publication 26 (ICRP77) was exposed at selected locations inside nuclear power stations. The effective dose equivalent was calculated and compared to the personal dosimeter response worn at the normal chest and waist locations. It was found that the EDE could be adequately measured and that the average rem/R conversion factor varied between 0.79 and 0.87, depending on the wearing position and sex of the worker.     

Impact of volumetric activity of radon on the concentration of air ions and on the power of electric field

This paper considers the impact of the volumetric activity of radon and its degradation products on the concentration of aeroions and on the strength of an electric field. The optimum range of the volumetric activity of this substance and its daughter degradation products, and their generated aeroions is substantiated. Technology has been developed for space- and time-combined measurements of the volumetric activity of radon, the density of radon flow from the ground surface, the concentration and mobility of negative and positive aeroions, and a difference in potentials of the electric component of atmospherics.     

Prediction of lethal/effective concentration/dose in the presence of multiple auxiliary covariates and components of variance

Predictors of the percentile lethal/effective concentration/dose are commonly used measures of efficacy and toxicity. Typically such quantal-response predictors (e.g., the exposure required to kill 50% of some population) are estimated from simple bioassays wherein organisms are exposed to a gradient of several concentrations of a single agent. The toxicity of an agent may be influenced by auxiliary covariates, however, and more complicated experimental designs may introduce multiple variance components. Prediction methods lag examples of those cases. A conventional two-stage approach consists of multiple bivariate predictions of, say, medial lethal concentration followed by regression of those predictions on the auxiliary covariates. We propose a more effective and parsimonious class of generalized nonlinear mixed-effects models for prediction of lethal/effective dose/ concentration from auxiliary covariates. We demonstrate examples using data from a study regarding the effects of pH and additions of variable quantities 2',5'-dichloro-4'-nitrosalicylanilide (niclosamide) on the toxicity of 3-trifluoromethyl-4-nitrophenol to larval sea lamprey (Petromyzon marinus). The new models yielded unbiased predictions and root-mean-squared errors (RMSEs) of prediction for the exposure required to kill 50 and 99.9% of some population that were 29 to 82% smaller, respectively, than those from the conventional two-stage procedure. The model class is flexible and easily implemented using commonly available software.     

左布比卡因复合芬太尼蛛网膜下腔分娩镇痛的最小有效剂量探讨

目的 探讨左布比卡因用于蛛网膜下腔分娩镇痛的最小有效剂量,为临床提供参考.方法 分娩镇痛的初产妇20例,ASA分级Ⅰ～Ⅱ级,产程进入活跃期,宫口扩张2～3 cm,经L2-3间隙用25 G蛛网膜下腔麻醉针缓慢注入2 ml重密度左布比卡因.第1例产妇接受的剂量为最低阶梯0.96 mg,其后每例产妇接受的左布比卡因剂量按照序贯方法确定.在注药后3 min,用乙醇涂擦法测试温度觉消失平面,用视觉模拟评分(VAS)评价宫缩疼痛强度.运用Dixon-Massey法计算半数有效量(ED50)及其95%可信区间.结果 根据Dixon-Massey法计算左布比卡因的ED50为1.63 mg,95%可信区间为1.48～1.80 mg.结论 左布比卡因可安全用于蛛网膜下腔分娩镇痛,其最小有效剂量为1.63 mg,95%可信区间为1.48～1.80 mg.     

Evaluation of exposure risk in the weaving process of MWCNT-coated yarn with real-time particle concentration measurements and characterization of dust particles

Various applications of multiwalled carbon nanotubes (MWCNT) have been developed. One of these applications is an efficient sheet heating element that is woven from MWCNT-coated yarn. In this research, we assessed the exposure to MWCNT and/or the probability of particle release from broken MWCNT-coated yarn during the weaving process. This was accomplished using particle concentrations, microscopic observation, and carbon analysis. In the weaving process, neither an increase in the number of particles nor a difference in particle-size distribution was observed. In the scanning electron micrographic observation, nanosize MWCNT particles were not detected, but there were micron-size particles containing MWCNT as fragments of the yarn. Carbon analysis showed the concentration of micron-size particles containing MWCNT did not exceed 0.0053 mg-C/m(3) around the loom. This value was much lower than the respirable dust mass concentration. Most of micron-size particles seemed to originate from polyester yarn without MWCNT coating. It is recommended that workers use conventional (even not specialized for nanoparticles) personal protective equipment such as respirators and gloves to prevent exposure to respirable-size MWCNT-containing particles. The probability of MWCNT fall-off from the MWCNT-coated yarn was not detected by transmission electron microscopic observation of MWCNT-coated yarn before or after the weaving process.     

冠心病患者血浆一氧化氮及一氧化氮合酶活力的研究

目的　探讨冠心病 (CHD)患者血浆一氧化氮 (NO)和一氧化氮合酶 (NOS)的水平差异以及其可能的影响因素。方法　采用试剂盒测定血浆中NO含量和NOS的活力 ,所得数据进行多元线性回归分析和协方差分析。结果　在本研究条件下 ,冠心病患者血浆NO含量为 (2 17.0 5± 15 3.31)μmol/L,NOS活力为 (14 .0 9± 7.14 )U/ml,均明显高于对照组 [分别为 (14 0 .6 9± 90 .96 ) μmol/L、(7.75±3.79)U/ml],差异有显著性 (P <0 .0 1)。吸烟和饮酒是血浆NOS的独立影响因素。性别是血浆NO的独立影响因素。结论　血浆NO和NOS与冠心病具有密切的关系。     

Reaction time and DPPH concentration influence antioxidant activity and kinetic parameters of bioactive molecules and plant extracts in the reaction with the DPPH radical

The antioxidant activity of lemon and pomegranate juice, infusion of Java green tea, rosemary oil and pure chemicals was studied by the DPPH method. The chemical composition of the samples was determined by liquid chromatography–mass spectrometry (LC–MS). The kinetics of the reaction is different among extracts. The reaction of DPPH with lemon juice is complete in 3 min; 87 and 98 min are necessary for green tea infusion and pomegranate juice, respectively; 283 min are needed for rosemary essential oil. In samples with an intermediate and slow kinetic behavior, the antioxidant activity measured after 2 h of reaction is significantly higher than that measured after 30 min. These differences are 18% for Java green tea infusion, 21% for rosemary essential oil, 23% for pomegranate juice. The results demonstrate that the percentage of remaining DPPH decreases with increasing initial DPPH concentrations (between 25 and 200 μM), while keeping constant antioxidant/DPPH ratio. Moreover the time necessary to reach the steady state is dependent, while keeping the same antioxidant/DPPH ratio, on the initial DPPH concentration, showing that longer time intervals are required when using lower DPPH concentrations (25 μM). These results confirm the necessity of standardizing the method to be able to compare results from different laboratories.     

Differential associations of mentally-active and passive sedentary behaviours and physical activity with putative cognitive decline in healthy individuals and those with bipolar disorder: Findings from the UK Biobank cohort

ObjectivePhysical activity confers protection against age-related cognitive dysfunction, but less is known about whether cognition is impacted by sedentary behaviour, specifically its mentally-active and passive forms. Both physical inactivity and sedentary behaviour are highly prevalent in bipolar disorder (BD), yet if and how they relate to the disorder's cognitive symptoms remains unclear. In this study, we explored whether individual variation in physical activity and sedentary behaviour was directly associated with cognition and/or moderated the extent of decrements in cognitive performance occurring as a function of age in people with BD versus psychiatrically-healthy controls.MethodsRelevant UK Biobank data were available for 1074 BD patients and 59,653 psychiatrically-healthy controls, aged 40–70. Age, mentally-active (computer use) and passive sedentary behaviour (TV viewing), physical activity, diagnosis, and their interactions were regressed on a global cognitive score.ResultsCognition was inversely associated with physical activity (β = −0.003, CI: −0.003, −0.003) and mentally-passive sedentary behaviour (β = −0.03, CI: −0.04, −0.02) and positively associated with mentally-active sedentary behaviour (β = 0.13, CI: 0.12, 0.15). The latter association was stronger in the BD group. Mentally-active sedentary behaviour moderated the age-cognition association in both BD patients and controls (β = 0.01, CI: 0.008, 0.01), such that age-related decrements in cognition were more apparent in those who engaged in less mentally-active sedentary behaviours compared to those who engaged in more.ConclusionsMentally-active sedentary behaviour may not only attenuate age-related cognitive dysfunction, but may be important for cognition irrespective of age, particularly in those with BD. These findings support the notion that intellectual stimulation is a protective factor conferring cognitive benefits, even in the context of a sedentary lifestyle.     

Mammary gene expression and activity of antioxidant enzymes and concentration of the mammalian lignan enterolactone in milk and plasma of dairy cows fed flax lignans and infused with flax oil in the abomasum

The objectives of the study were to investigate the effects of dietary supplementation of flax hulls and/or flax oil on the activity of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX)) in plasma and the mammary gland and the relative mRNA abundance of antioxidant genes in the mammary gland of dairy cows. A total of eight dairy cows were used in a replicated 4?×?4 Latin square design. There were four treatments: control with no flax hulls (CONT), 9·88?% flax hulls in the DM (HULL), control with 500?g flax oil/d infused in the abomasum (COFO), 9·88?% flax hulls in the DM and 500?g flax oil/d infused in the abomasum (HUFO). Plasma GPX activity tended to decrease with flax oil supplementation. Cows fed HULL had higher levels of CAT, GPX1 and SOD1 mRNA in the mammary gland and lower mRNA abundance of GPX3, SOD2 and SOD3 compared with those fed CONT. Abundance of CAT, GPX1, GPX3, SOD2 and SOD3 mRNA was down-regulated in the mammary gland of cows fed HUFO compared to those fed CONT. The mRNA abundance of CAT, GPX1, GPX3 and SOD3 was lower in the mammary gland of cows fed COFO than in the mammary gland of cows fed CONT. The present study demonstrates that flax hulls contribute to increasing the abundance of some antioxidant genes, which can contribute to protecting against oxidative stress damage occurring in the mammary gland and other tissues of dairy cows.