Spillover effects of trade and foreign direct investment on economic growth: an implication for sustainable development

Environment, Development and Sustainability - This paper explores the advantages of international trade and foreign direct investment (FDI), which can be the main factors of transferring technology...     

Exposure to methyl methacrylate and its subjective symptoms among dental technicians, Tehran, Iran.

Exposure to methyl methacrylate (MMA), total dust and health symptoms were investigated in 20 dental laboratories located in Tehran, Iran. Time-weighted average (TWA) of MMA and peak concentrations were determined, using XAD-2 tubes followed by GC-FID analysis. Total dusts were evaluated gravimetrically. Health symptoms were asked using a questionnaire. TWA for technicians with direct and indirect exposure to MMA were 327.28 +/- 79.42 and 282.9 +/- 41.84 mg/m3, respectively. Peak concentration of MMA for those technicians were 337.0 +/- 36.81 and 328.88 +/- 45.40 mg/m3, respectively. There were no significant differences between TWA of MMA and peak concentration in different weekly workdays; however, within-day variations were observed (P < .05). TWA of MMA and peak concentration correlation with the laboratory volume were 0.61-0.65. Dust exposure of technicians was 2.35 +/- 2.70 mg/m3. Cough and skin dryness were the common health symptoms. Smoking and asbestos exposure history were factors influencing cough prevalence (p < .05). It is concluded that the current Short-Term Exposure Limit (STEL) is not low enough to protect technicians against the adverse effects caused by MMA.     

Phyto-management of Cr-contaminated soils by sunflower hybrids: physiological and biochemical response and metal extractability under Cr stress

Environmental Science and Pollution Research - Chromium (Cr) is a biologically non-essential, carcinogenic and toxic heavy metal. The cultivation of Cr-tolerant genotypes seems the most favorable...     

Toward a robust analytical method for separating trace levels of nano-materials in natural waters: cloud point extraction of nano-copper(II) oxide

Cloud point extraction (CPE) factors, namely Triton X-114 (TX-114) concentration, pH, ionic strength, incubation time, and temperature, were optimized for the separation of nano-sized copper(II) oxide (nCuO) in aqueous matrices. The kinetics of phase transfer was studied using UV–visible spectroscopy. From the highest separation rate, the most favorable conditions were observed with 0.2 %?w/v of TX-114, pH?=?9.0, ionic strength of 10 mM NaCl, and incubation at 40 °C for 60 min, yielding an extraction efficiency of 89.2?±?3.9 % and a preconcentration factor of 86. The aggregate size distribution confirmed the formation of very large nCuO–micelle assemblies (11.9 μm) under these conditions. The surface charge of nCuO was also diminished effectively. An extraction efficiency of 91 % was achieved with a mixture of TX-100 and TX-114 containing 30 wt.% of TX-100. Natural organic and particulate matters, represented by humic acid (30 mg/L) and micron-sized silica particles (50 mg/L), respectively, did not significantly reduce the CPE efficiency (<10 %). The recovery of copper(II) ions (20 mg/L) in the presence of humic acid was low (3–10 %). The spiked natural water samples were analyzed either directly or after CPE by inductively coupled plasma mass spectrometry following acid digestion/microwave irradiation. The results indicated the influence of matrix effects and their reduction by CPE. A delay between spiking nCuO and CPE may also influence the recovery of nCuO due to aggregation and dissolution. A detection limit of 0.04 μg Cu/L was achieved for nCuO.     

Health risk assessment of PAHs in fruit juice samples marketed in city of Tehran,Iran

Environmental Science and Pollution Research - The objective of the present study was to investigate the level of 16 PAHs in fruit juice samples (orange, apple, peach, pineapple, and mango) with...     

The effect of nutrients shortage on plant’s efficiency to capture solar radiations under semi-arid environments

Radiation use efficiency (RUE) is considered critical for calculation of crop yield. The crop productivity can be improved by increasing the interception of solar radiation and maintaining higher RUE for plants. Irrigation water and nitrogen (N) supply are the main limiting factors for RUE in maize (Zea mays L.) across the semi-arid environments. Field experiments were conducted during two consecutive growing seasons (2009–2010) to optimize RUE in relation to N application timings and rates with varying irrigation water management practices. In experiment 1, three N application timings were made, while in experiment 2, three possible water management practices were used. In both experiments, five N rates (100, 150, 200, 250, and 300 kg N ha⁻¹) were applied to evaluate the effects of irrigation water and N on cumulative photosynthetic active radiation (PARi), dry matter RUE (RUE_DM), and grain yield RUE (RUE_GY). The results demonstrated that cumulative PARi and RUEs were not constant during the plant growth under varying the nutrients. The water and N significantly influenced cumulative PARi and RUEs during the both growing seasons. In experiment 1, the maximum cumulative PARi was observed by application of 250 kg N ha⁻¹ in three splits (1/3 N at V2, 1/3 N at V16, and 1/3 N at R1 stage), and the highest RUE_DM was achieved by the application of 300 kg N ha⁻¹. However, the highest RUE_GY was observed by application of 250 kg N ha⁻¹. In experiment 2, the maximum cumulative PARi was attained at normal irrigation regime with 250 kg N ha⁻¹, while the highest RUE_DM and RUE_GY were recorded at normal irrigation regime with the application of 300 kg N ha⁻¹. The regression analysis showed significant and positive correlation of RUE_GY with grain yield. Therefore, optimum water and N doses are important for attaining higher RUE, which may enhance maize grain yield semi-arid environment; this may be considered in formulating good agricultural practices for the environmental conditions resembling to those of this study.

     

A path analysis model for explaining unsafe behavior in workplaces: the effect of perceived work pressure

Background. Unsafe behavior is closely related to occupational accidents. Work pressure is one the main factors affecting employees’ behavior. The aim of the present study was to provide a path analysis model for explaining how work pressure affects safety behavior. Methods. Using a self-administered questionnaire, six variables supposed to affect safety employees’ behavior were measured. The path analysis model was constructed based on several hypotheses. The goodness of fit of the model was assessed using both absolute and comparative fit indices. Results. Work pressure was determined not to influence safety behavior directly. However, it negatively influenced other variables. Group attitude and personal attitude toward safety were the main factors mediating the effect of work pressure on safety behavior. Among the variables investigated in the present study, group attitude, personal attitude and work pressure had the strongest effects on safety behavior. Conclusion. Managers should consider that in order to improve employees’ safety behavior, work pressure should be reduced to a reasonable level, and concurrently a supportive environment, which ensures a positive group attitude toward safety, should be provided. Replication of the study is recommended.     

Wood Plastic Composite Panels: Influence of the Species,Formulation Variables and Blending Process on the Density and Withdrawal Strength of Fasteners

In this work, the influence of four variable parameters including fiber types (poplar and rice straw), fiber contents (45, 60, and 75 wt%), fiber sizes (20–40 and 40–60 mesh), and blending methods (hot-pressing and extrusion) on the physico-mechanical properties of wood plastic composite panels were studied. Generally, the results showed that each of the above-mentioned parameters had significant effect on the nail and screw withdrawal strength (pull-out load) and density, whereas their interactions did not have highly impressive effects on the properties. All tested properties vary significantly with fiber origin. Composites filled with larger fiber size, produced panels with higher withdrawal strength and density. The effect of blending method on density was maximal. Withdrawal strength values of each sample decreased with increase in fiber loading. The lowest withdrawal strength values of nail and screw were obtained from the samples filled with rice straw. It was found that strength properties of the composites can be improved moderately by adding 45 wt% fiber, 20–40 mesh particle and poplar flour. According to the results, the blending method is a significant variable in the determination of withdrawal strength. Therefore, the blending method can be recommended based on the end product applications.