Modeling in-stream attenuation of N-nitrosodimethylamine and formaldehyde during urban river transportation based on seasonal and diurnal variation

Environmental Science and Pollution Research - Disinfection by-products (DBPs) discharged from sewage treatment plants (STPs) could harm downstream receiving waters and drinking water resources....     

Biocompatible Polyurethane Scaffolds Prepared from Glycerol Monostearate-Derived Polyester Polyol

Biodegradable polyester polyol was synthesized from oleochemical glycerol monostearate (GMS) and glutaric acid under a non-catalyzed and solvent-free polycondensation method. The chemical structure of GMS-derived polyester polyol (GPP) was elucidated by FTIR, ¹H and ¹³C NMR, and molecular weight of GPP was characterized by GPC. The synthesized GPP with acid value of 3.03 mg KOH/g sample, hydroxyl value of 115.72 mg KOH/g sample and M_n of 1345 g/mol was incorporated with polyethylene glycol (PEG) and polycaprolactone diol (PCL diol) to produce a water-blown porous polyurethane system via one-shot foaming method. The polyurethanes were optimized by evaluating glycerol as a crosslinker, silicone surfactant and water blowing agent on tensile properties of polyurethanes. All polyurethanes underwent structural change, and crystalline hard segments of polyurethanes were shifted to higher temperature suggested that hard segments undergone re-ordering process during enzymatic treatment. In terms of biocompatibility, polyurethane scaffold produced by reacting 100% w/w of GPP with isophorone diisocyanate and additives showed the highest cells viability of 3T3 mouse fibroblast (94%, day 1), and MG63 human osteosarcoma (107%, day 1) and better cell adhesion as compared to reference polyurethane produced by only PEG and PCL diol (3T3 cell viability: 8%; MG63 cell viability: 2%). The current work demonstrated GPP synthesized from renewable and environmental friendly resources produced polyurethanes that allows improvement in physico-chemical, mechanical and biocompatibility properties. By blending with increasing content of GPP, the water-blown porous polyurethane scaffold has shown great potential as biomaterial for soft and hard tissue engineering.     

Feeding and metabolism effects of three common microplastics on Tenebrio molitor L.

Environmental Geochemistry and Health - Mealworms from three different regions: Guangzhou, Tai’an and Shenzhen, were fed with three commonly used microplastics of polystyrene (PS), polyvinyl...     

An Ergonomics Study of a Semiconductors Factory in an IDC for Improvement in Occupational Health and Safety

The study aimed to conduct an ergonomic intervention on a conventional line (CL) in a semiconductor factory in Malaysia, an industrially developing country (IDC), to improve workers’ occupational health and safety (OHS). Low-cost and simple (LCS) ergonomics methods were used (suitable for IDCs), e.g., subjective assessment, direct observation, use of archival data and assessment of noise. It was found that workers were facing noise irritation, neck and back pains and headache in the various processes in the CL. LCS ergonomic interventions to rectify the problems included installing noise insulating covers, providing earplugs, installing elevated platforms, slanting visual display terminals and installing extra exhaust fans. The interventions cost less than 3 000 USD but they significantly improved workers’ OHS, which directly correlated with an improvement in working conditions and job satisfaction. The findings are useful in solving OHS problems in electronics industries in IDCs as they share similar manufacturing processes, problems and limitations.     

PCDD/PCDF,chlorinated pesticides and PAH in Chinese teas

Four samples of Chinese tea (two green teas, and two brick teas) were analyzed for their concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF), chlorinated pesticides and PAH. The infusions prepared from these teas were also analyzed for PCDD/PCDF. The levels of DDT and its metabolites in tea leaves were within the safety limit of 0.2 mg/kg. Rather high levels of total PAH were obtained in brick tea (1048–1162 mg/kg), when compared with green tea (497–517 mg/kg). In terms of PCDD/PCDF, the concentrations of green tea and brick tea differed by a factor of 16, while the concentrations of all infusions were within a factor of 2. The dioxin concentrations in green tea leaves can be explained through uptake of atmospheric PCDD/PCDF. The higher concentrations in the brick tea leaves are due the longer exposure time, and to certain extent, the use of old leaves, branches and roots when making the tea, and additional components such as soil particulates through contamination. Certain Chinese populations drinking a large amount of brick tea (>3 l per day) indicated that individuals of these populations consume more tea than Europeans or North Americans result in a comparably higher intake of PCDD/PCDF. Tea consumption can attribute to up to 10% of the TDI recommended by WHO (only PCDD/PCDF considered, no PCB analyzed).     

Field investigation of the quality of fresh and aged leachates from selected landfills receiving e-waste in an arid climate

The management of electronic waste (e-waste) is a serious problem worldwide and much of it is landfilled. A survey of four selected landfills in an arid region of South Australia was conducted to determine the proportion of e-waste in municipal waste and the properties of each landfill site. Leachate and groundwater samples were collected upgradient and downgradient of the landfills for analysis of polybrominated diphenyl ethers (PBDEs) and 14 metals and metalloids, including Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Ni, Pb, Sb, V and Zn. Our data demonstrate that the selected landfills in South Australia continue to receive municipal waste containing in excess of 6%, or 25,000 tonnes per year, of e-waste. The leachates and groundwater collected from the landfills contained significantly elevated concentrations of Pb with the highest concentration in groundwater of 38 μg/l, almost four times higher than the Australian drinking water guideline of 10 μg/l. The presence of PBDEs was detected in both leachate and groundwater samples. Total PBDEs values of 2.13–59.75 ng/l in leachate samples were 10 times higher than in groundwater samples, which recorded a range of 0.41–6.53 ng/l at all sites. Moreover, the concentrations of metals and metalloids in sampled groundwater contained elevated levels of Al, As, Fe, Ni and Pb that exceeded Australian drinking water guideline values. For these reasons potential leaching of these contaminants is of concern and while difficult to attribute elevated contaminant levels to e-waste, we do not recommend continued disposal of e-waste in old landfills that were not originally designed to contain leachates. The survey also revealed temporal variation in the electrical conductivity and concentrations of As, Cd and Pb present in leachates of landfills in arid Mediterranean climates. These results are consistent with the marked variations in rainfall patterns observed for such climates. The solute concentration (EC and other ions including As, Cd and Pb) declines in the leachates during wet winter months (June to September), in contrast to tropical countries where such changes are observed during wet summer months.     

A review on the formation of titania nanotube photocatalysts by hydrothermal treatment

Titania nanotubes are gaining prominence in photocatalysis, owing to their excellent physical and chemical properties such as high surface area, excellent photocatalytic activity, and widespread availability. They are easily produced by a simple and effective hydrothermal method under mild temperature and pressure conditions. This paper reviews and analyzes the mechanism of titania nanotube formation by hydrothermal treatment. It further examines the parameters that affect the formation of titania nanotubes, such as starting material, sonication pretreatment, hydrothermal temperature, washing process, and calcination process. Finally, the effects of the presence of dopants on the formation of titania nanotubes are analyzed.     

Adjustment of brood care behaviour in the absence of a mate in two species of Nicaraguan crater lake cichlids

In many taxa, parental strategies can vary among individuals. This is especially true in species with biparental care, with males, more often than females, deserting their mates. While there is an abundance of theoretical predictions and empirical data on factors inducing mate abandonment by males, much less is known about what consequences this may have on female behaviour, particularly in the field and in non-avian systems. Here, we compared brood defence rate, behavioural defence types, and brood success of solitary and paired females in two species of Neotropical cichlid fish in their natural habitat. In terms of the rate of territorial aggression towards potential brood predators, solitary females were able to fully compensate in the absence of a male but, in so doing, ended up maintaining smaller territories, which appeared to compromise offspring fitness in at least one of the two species. Hence, our results suggest that even extensive quantitative compensation in parental effort by solitary females may not be enough to ensure adequate qualitative compensation for the lack of male participation, highlighting the importance of distinguishing between these two aspects of compensatory parental care.     

Photocatalytic defluorination of perfluorooctanoic acid by surface defective BiOCl: Fast microwave solvothermal synthesis and photocatalytic mechanisms

There is an urgent need for developing cost-effective methods for the treatment of perfluorooctanoic acid(PFOA)due to its global emergence and potential risks.In this study,taking surface-defective BiOCl as an example,a strategy of surface oxygen vacancy modulation was used to promote the photocatalytic defluorination efficiency of PFOA under simulated sunlight irradiation.The defective BiOCl was fabricated by a fast microwave solvothermal method,which was found to induce more surface oxygen vacancies than conventional solvothermal and precipitation methods.As a result,the asprepared BiOCl showed significantly enhanced defluorination efficiency,which was 2.7 and33.8 times higher than that of BiOCl fabricated by conventional solvothermal and precipitation methods,respectively.Mechanistic studies indicated that the defluorination of PFOA follows a direct hole(h~+)oxidation pathway with the aid of·OH,while the oxygen vacancies not only promote charge separation but also facilitate the intimate contact between the photocatalyst surface and PFOA by coordinating with its terminal carboxylate group in a bidentate or bridging mode.This work will provide a general strategy of oxygen vacancy modulation by microwave-assisted methods for efficient photocatalytic defluorination of PFOA in the environment using sunlight as the energy source.