Porosity distribution by computed tomography and its importance to characterize soil clod samples

Gamma-ray computed tomography (CT) was employed to study the soil quality of clod samples used to investigate porosity (ϕ). Samples with volumes varying from 50 to 100 cm³ were collected from the soil surface. 2D CT images were obtained with millimetric resolution. Porosity distribution analyses were carried out to infer the soil clod structure. Results obtained provided a new insight on the variability of internal clod structure due to the large amount of data analyzed, information that is not provided by traditional methods used in physics applied to soil.     

Starch-encapsulated chlorpyrifos: release rate,insecticidal activity and degradation in soil

Incorporation of chlorpyrifos into starch matrices was achieved by thermal gelatinization. The level of amylose content in the starch matrices (10 and 52%) and the addition of auxiliary agents, i.e. solvent, emulsifiers or both, were varied and eight different formulations were prepared. According to differential scanning calorimetry (DSC) and X-ray diffraction measurements, chlorpyrifos was partly present in a crystalline form in all the starch formulations. The formulations had controlled release properties, and the release rate into water could be described by a linear model. In a bioassay, the formulations killed all larvae of the cabbage root fly at a dosing of 1.4 kg a.i. per ha. The degradation of chlorpyrifos in soil from the starch formulations could be described in a nonlinear logistic model and the half-life was predicted to be 88 days. Differences in the amount of amylose in the starch as well as the addition of solvent and emulsifiers in the preparation procedure had no systematic influence on the release rate, the insecticidal effect and the degradation rate. No correlation between release rate into water and degradation in soil could be established. Two commercial chlorpyrifos formulations Lorsban#174; 15 G (granular) and Cyfos#174; 500 gl -1 (emulsifiable concentrate), were included in the study for comparison.     

Molecular characterization of Toxocara spp. from soil of public areas in Ahvaz southwestern Iran

In the present study, the microscopy and polymerase chain reaction methods were used for detection and identification of soil contamination by Toxocara eggs in squares, streets, public parks, and rubbish dumps in Ahvaz, southwestern Iran.     

Criteria of radon risk of territories and methods for their determination

The paper analyzes the values used in the assessment of radon potential of territories. It was shown that the most reliable criterion in the assessment of radon risk of territories can be the value of radon activity concentration fixed at large depths. The authors proposed a simple method to assess this value and radon flux density from the soil surface, based on the measurement of radon activity concentration in soil gas at two twice differing depths and the diffusion model of transport.     

Natural and anthropogenic radioactivity levels and the associated radiation hazard in the soil of Oodalia Tea Estate in the hilly region of Fatickchari in Chittagong,Bangladesh

Radioactivity in the soil of a tea garden in the Fatickchari area in Chittagong, Bangladesh, was measured using a high-resolution HPGe detector. The soil samples were collected from depths of up to 20 cm beneath the soil surface. The activity concentrations of naturally occurring ²³⁸U and ²³²Th were observed to be in the range of 27 ± 7 to 53 ± 8 Bq kg⁻¹ and 36 ± 11 to 72 ± 11 Bq kg⁻¹, respectively. The activity concentration of ⁴⁰K ranged from 201 ± 78 to 672 ± 81 Bq kg⁻¹, and the highest activity of fallout ¹³⁷Cs observed was 10 ± 1 Bq kg⁻¹. The average activity concentration observed for ²³⁸U was 39 ± 8 Bq kg⁻¹, for ²³²Th was 57 ± 11 Bq kg⁻¹, for ⁴⁰K was 384 ± 79 Bq kg⁻¹ and for ¹³⁷Cs was 5 ± 0.5 Bq kg⁻¹. The radiological hazard parameters (representative level index, radium equivalent activity, outdoor and indoor dose rates, outdoor and indoor annual effective dose equivalents, and radiation hazard index) were calculated from the radioactivity in the soil.     

On the calculation of activity concentrations and nuclide ratios from measurements of atmospheric radioactivity

Motivated by the need for consistent use of concepts central to the reporting of results from measurements of atmospheric radioactivity, we discuss some properties of the methods commonly used. Different expressions for decay correction of the activity concentration for parent–daughter decay pairs are presented, and it is suggested that this correction should be performed assuming parent–daughter ingrowth in the sample during the entire measurement process. We note that, as has already been suggested by others, activities rather than activity concentrations should be used when nuclide ratios are calculated. In addition, expressions that can be used to transform activity concentrations to activity ratios are presented. Finally we note that statistical uncertainties for nuclide ratios can be properly calculated using the exact solution to the problem of confidence intervals for a ratio of two jointly normally distributed variables, the so-called Fieller׳s theorem.     

医用直线加速器的感生放射性研究

医用直线加速器在治疗过程中会产生对人体有害的感生放射性,且这种危害正逐渐引起人们的重视。本文介绍了感生放射性的概念、产生机制,总结感生放射性对患者、工作人员及公众所造成的危害,探讨了感生放射性水平的影响因素,并总结减少其水平的措施。     

陕北农村地区居民土源性线虫感染调查分析

目的 了解陕北农村居民土源性线虫感染现状、土源性线虫病防治知识知晓及健康行为形成情况.方法 按照随机抽样法,选择8个村作为调查点,以调查点≥3岁的常住人口为调查对象.采用改良加藤厚涂片法检测调查对象粪便中蛔虫、钩虫、鞭虫虫卵,12周岁以下儿童以透明胶纸法检测蛲虫卵.在每个调查点随机抽取8户以上的家庭,对家庭成员进行土源性线虫病防治知识知晓情况及卫生行为调查.结果 共粪检1 352人,阳性4人,土源性线虫总感染率为0.29％;蛲虫感染检测108人,阳性11人,蛲虫感染率为10.18％;入户调查329人,土源性线虫病防治知识知晓率为38.29％,62％以上的调查者有良好卫生行为.结论 陕北农村居民土源性线虫感染率较低,但儿童蛲虫感染率较高;人群卫生行为较好,但防治知识知晓率偏低.应继续加强防治工作,促进健康教育,以有效降低该病的危害.     

Absorption,distribution, metabolism and excretion of novel phosphodiesterase type 4 inhibitor ASP3258 in rats

The potent and selective phosphodiesterase 4 inhibitor ASP3258 is a novel therapeutic agent for asthma and chronic obstructive pulmonary disease (COPD). After a single oral administration to rats, ASP3258 is rapidly absorbed with a bioavailability of 106%. In situ absorption data indicated that ASP3258 is mainly absorbed in the small intestine. Tissue distribution data after oral administration of ¹⁴C‐ASP3258 showed rapid and extensive distribution to various tissues. Excluding the gastrointestinal tract, the tissues with the highest concentrations were liver, heart and plasma. Liquid chromatography‐nuclear magnetic resonance spectroscopy data revealed that O‐glucuronidation of the carboxylic acid moiety of ASP3258 (formation of an acyl glucuronide) plays a key role in metabolism. No indication was found that the acyl glucuronide reacted with proteins in plasma or tissues. When ¹⁴C‐ASP3258 was orally administered to intact rats, urinary and fecal excretion accounted for 1.3% and 100.6% of the administered radioactivity, respectively. After a single oral administration of ¹⁴C‐ASP3258 to bile‐cannulated rats, urinary and biliary excretion accounted for 0.7% and 93.8% of the administered radioactivity, respectively. These findings suggest that fecal excretion via bile plays an important role in the elimination of ASP3258‐derived radioactivity. In vitro metabolic profiles were relatively similar among the species examined, suggesting that our findings in rats may help us to understand pharmacokinetics, efficacy and safety profiles in humans and other species. Copyright © 2014 John Wiley & Sons, Ltd.