In this study, a ternary Zr(IV) system with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) and fluoride was chosen on the basis of dispersive liquid–liquid microextraction method. Zirconium was extracted into the fine droplets of dichlorobenzene as extracting solvent. These drops dispersed as a cloud in the aqueous sample with the help of ultrasonic waves, and the procedure was done. Finally, atomic absorption spectrometry was applied for the determination of zirconium. The effects of different factors that influence complex formation and extraction, such as pH, amounts of complexing agents, type and volume of the extracting solvent, as well as sonication and centrifuging time, were optimized. Under optimum conditions, the calibration curve was linear in the range of 150.0–800.0 ng mL?1 with a limit of detection of 44.0 ng mL?1. Relative standard deviation was calculated to be 4.1 % (n?=?7, c?=?400.0 ng mL?1). The enrichment factor was 80. The proposed method was successfully used to determine the zirconium in several water, wastewater, and soil samples. 相似文献
Formaldehyde has been classified in group 1 as a potential source of human carcinogen by the International Agency for Research on Cancer. In this study, we evaluated the DNA damage in workers who were occupationally exposed to formaldehyde during the manufacture of melamine dinnerware.
Age, sex, smoking habits, and socioeconomic status were matched by the controls (n = 34) of workers not occupationally exposed to formaldehyde. The median value of formaldehyde time weighted average exposure in three workshops was 0.086 mg/m3. No significant difference was observed between sex and smoking habit in the assessed workers. Alkaline comet assay of peripheral blood lymphocytes was used to determine the DNA damage in the subjects. Olive moment was significantly higher in the exposed group compared with the control group.
Overall, the results suggest that respiratory exposure to low concentrations of formaldehyde causes DNA damage in peripheral blood lymphocyte. Therefore, exposure to formaldehyde should be reduced to the lowest possible level. 相似文献
Environmental Science and Pollution Research - The validation of an analytical procedure based on the quick, easy, cheap, effective, rugged, and safe (QuEChERS) approach is presented for... 相似文献
Eleven effective low-density polyethylene (LDPE)-degrading bacterial strains were isolated and identified from landfill soil containing large amounts of plastic materials. The isolates belonged to 8 genera, and included Pseudomonas (areroginosa and putida), Sphingobacterium (moltivorum), Delftia (tsuruhatansis), Stentrophomonas (humi and maltophilia), Ochrobacterum (oryzeae and humi), Micrococcus (luteus), Acinetobacter (pitti), and Citrobacter (amalonaticus). Abiotic degradation of LDPE films by artificial and natural ultraviolet (UV)-exposure was analyzed by FT-IR spectroscopy. LDPE films treated with UV-radiation were also inoculated with the isolates and biofilm production and LDPE degradation were measured. Surface changes to the LDPE induced by bacterial biofilm formation were visualized by Scanning Electron Microscopy. The most active bacterial isolate, IRN19, was able to degrade polyethylene film by 26.8?±?3.04% gravimetric weight over 4 weeks. Analysis of 16S rRNA sequence of this isolate revealed 96.97% similarity in sequence to Acinetobacter pitti, which has not previously been identified as a polyethylene-degrading bacterium. Also, most the effective biofilm forming isolate, IRN11, displayed the highest cell mass production (6.29?±?0.06 log cfu/cm2) after growth on LDPE films, showed 98.74% similarity to Sphingobacterium moltivourum. 相似文献
Environmental Science and Pollution Research - UV filters as an important class of emerging organic pollutants are continuously released into and transported between the aquatic environments. So,... 相似文献
Mesoporous nickel oxide (MNO) was synthesized by sol–gel method with saponificated chlorophyll-a (Chl-a) as template and Ni (II) acetate as starting material. XRD, surface area, pore volume, pore diameter and pore size distribution
of MNO were determined. It exhibited high surface area and uniform pores with very sharp pore size distribution centered at
3.6 nm. High resolution transmission electron microscope images confirmed the results. MNO showed a high activity toward degradation
of phenol at low temperature under atmospheric pressure of oxygen. 相似文献
The process of risk assessment of biotechnologies, such as genetically modified organisms (GMOs), has normative dimensions.
However, the US’ Food and Drug Administration (FDA) seems committed to the idea that such evaluations are objective. This
essay makes the case that the agency’s regulatory approach should be changed such that the public is involved in deciding
any ethical or social questions that might arise during risk assessment of GMOs. It is argued that, in the US, neither aggregative
nor deliberative (representative) democracy ought to be used to make such determinations. Instead, participatory (deliberative)
democracy should be the means by which members of the polity decide which normative concerns ought to underlie FDA’s assessment
of GMOs. This paper uses a hypothetical case involving a new GM seed to make that argument. 相似文献
Through a review of literature from diverse disciplines with actual and potential application to causal modeling of organizational safety risk, this paper explores issues regarding measurement techniques in a quantitative safety analysis context. The interdependencies of modeling perspectives, constructs, and measures are indentified, leading to (a) characterization and classification of measurement techniques, (b) suggestions on the selection of appropriate measurement methods for different types of model constructs including individual-level, global, configural, and shared, and (c) discussion of the modeling implications of interactions between measurement, constructs, and causal paths. A multi-dimensional perspective is offered through combinations of different “measurement methods” and “measurement bases”. A Bayesian approach is also proposed to operationalize the multi-dimensional measurements. Examples are provided to help explain the roles of these measurements in capturing the relation between organizational factors and safety performance. This paper is a product of research which has the primary purpose of extending Probabilistic Risk Assessment (PRA) modeling frameworks to include the effects of organizational factors as the fundamental causes of accidents and incidents. 相似文献
Journal of Polymers and the Environment - In this study, composite packaging films were produced from relatively inexpensive materials including Whey protein isolate (WPI) and Persian gum (PG),... 相似文献
Environmental Science and Pollution Research - The presence of potentially toxic elements (PTEs) in crops can directly/indirectly affect consumers’ health. The contamination of apple as one... 相似文献