Photocatalytic transfer of aqueous nitrogen into ammonia using nickel-titanium-layered double hydroxide.

The development of solar-driven transfer of atmospheric nitrogen into ammonia is one of the green and sustainable strategies in industrial ammonia production. Nickel-titanium-layered double hydroxide (NiTi-LDH) was synthesised using the soft-chemical process for atmospheric nitrogen fixation application under photocatalysis in an aqueous system. NiTi-LDH was investigated using advanced characterisation techniques and confirmed the potential oxygen vacancies and/or surface defects owing to better photocatalytic activity under the solar spectrum. It also exhibited a bandgap of 2.8 eV that revealed its promising visible-light catalytic activities. A maximum of 33.52 µmol L-1 aqueous NH3 was obtained by continuous nitrogen (99.9% purity) supply into the photoreactor under an LED light source. Atmospheric nitrogen supply (≈78%) yielded 14.67 µmol L-1 aqueous NH3 within 60 min but gradually reduced to 3.6 µmol L-1 at 330 min. Interestingly, in weak acidic pH, 20.90 µmol L-1 NH3 was produced compared to 11.51 µmol L-1 NH3 in basic pH. The application of NiTi-LDH for visible-light harvesting capability and photoreduction of atmospheric N2 into NH3 thereby opens a new horizon of eco-friendly NH3 production using natural sunlight as alternative driving energy.

Dynamically driven perovskite La-Fe-modified SrTiO3 nanocubes and their improved photoresponsive activity under visible light: influence of alkaline environment.

Visible-light active La-Fe-SrTiO3 (La0.01Sr0.99Fe0.01Ti0.99O3) photocatalysts were synthesized via a dynamic hydrothermal route under different NaOH concentrations (2, 3, 4, 5, and 6 M). The results showed that altering NaOH concentrations changed the physicochemical characteristics of the materials. Namely, the decrease in particle size was observed when the NaOH levels were increased. The specific surface area of the photocatalysts changed with an increased concentration of NaOH, and the maximum value was 17.10 m2/g in 5 M of NaOH. The crystal structure of all prepared samples remained unaffected when altered the NaOH concentration or when incorporated La and Fe in the lattice of SrTiO3. Namely, all samples synthesized under various NaOH concentrations crystallized and maintained in the standard cubic perovskite structure of SrTiO3. The increased NaOH concentration slightly altered the absorption wavelength towards a longer wavelength region. The La atom, replacing some Sr2+ in the structure of modified SrTiO3, was confirmed to be in the La3+ valence state. Simultaneously, Fe atoms demonstrating oxidation states of Fe3+ can also be incorporated into the SrTiO3 network. The photocatalytic degradation of ciprofloxacin antibiotic revealed that the highest performance was approximately 75% within 9 h over the La0.01Sr0.99Fe0.01Ti0.99O3 sample prepared at 5 M of NaOH via the dynamic hydrothermal process. Meanwhile, this photocatalyst also displayed greater activity than the pristine SrTiO3, the single-doped samples (SrFe0.01Ti0.99O3 and La0.01Sr0.99TiO3), and the La0.01Sr0.99Fe0.01Ti0.99O3 sample prepared through a static hydrothermal technique under the same synthesis condition.

Photocatalytic removal of 2,4-Dichlorophenoxyacetic acid from aqueous solution using tungsten oxide doped zinc oxide nanoparticles immobilised on glass beads.

Groundwater is the only source of high quality water for human consumption in most parts of the world; however, it can be easily contaminated by domestic, industrial, and agricultural wastes such as fertilisers and pesticides. The main objective of the present research was to study the photocatalytic removal of 2,4-Dichlorophenoxyacetic acid pesticide (2,4-D) from aqueous media. This was a laboratory scale study in which the zinc oxide nanoparticles were doped with 0.5, 1, and 2 molar percent of tungsten oxide. The nanoparticles synthesised were characterised using powder XRD, SEM, FTIR, and UV-Vis Spectroscopy analyses. During the photodegradation of 2,4-D, the operational parameters studied were pH, nanoparticles dosage, initial pesticide concentration, light intensity, contact time, and the mineralisation trend of organic matter. It was found that the doped nanoparticles had a smaller band gap energy, which confirms the effect of doping. The percentage of the dopant can affect the pesticide removal efficiency. The optimal pH value obtained was 7. In addition, the process efficiency, increased from 27% to 78% with increasing UV light intensity from 172 to 505 W/m2 respectively. Moreover, it was found that, with increasing light intensity, contact time and nanoparticle concentration all caused the pesticide removal efficiency to be increased too. In addition, the increase of the pesticide concentration would cause a reduction in the process removal efficiency. This study indicated that the photocatalytic process using tungsten doped zinc oxide nanoparticles can remove the 2,4-D pesticide by around 80% from the aquatic environment.

Correction to: Influence of iron mining activity on heavy metal contamination in the sediments of the Aqyazi River, Iran.

The original version of this article unfortunately contained an error in the affiliation section and missing acknowledgment statement.

Influence of iron mining activity on heavy metal contamination in the sediments of the Aqyazi River, Iran.

In order to investigate the degree of contamination of heavy metals (As, Cd, Cr, Cu, Fe, Pb, and Ni) in the Aqyazi River in Iran, sediment samples were collected from the river receiving wastewater from an iron-manufacturing plant. For this study, contamination indices, geoaccumulation index (Igeo), contamination factor (CF), and pollution load index (PLI), were used to assess contamination by the heavy metals. The results of the Igeo indicated that the sediments were moderately contaminated by Cu and strongly to extremely contaminated by Cd. Based on spatial distribution of concentrations and the Igeo, mining activity was the source of Cu and Cd in the Aqyazi River. Furthermore, the elevated Igeo of Cd at upmost northern station was not influenced by the mining activity, suggesting that there may be another upstream anthropogenic source of Cd. The CF values indicated the same trend as the Igeo. The PLI was calculated using all the metals analyzed in this study, and displayed that the sediments were not polluted. However, the PLI was re-calculated using only Cu and Cd and indicated that the sediments were polluted. Our results suggest further studies to trace another source of Cd upstream of the Aqyazi River and to investigate influence of the river waters on accumulation of heavy metals in soils and vegetables downstream.

The nitrate content of fresh and cooked vegetables and their health-related risks.

BACKGROUND: Vegetables are the most important source of nitrates in the human diet. During various processes in the body, nitrates are converted into nitrites, which causes various diseases, such as blue baby syndrome and cancer. This study aimed to determine the concentration of nitrates in several vegetable farms in Sanandaj city and to evaluate their health-related risks. METHODS: This descriptive cross-sectional study was conducted from October 2017 to July 2018. A total of 90 samples were taken from nine farms. Soil and water sampling was also carried out. All stages of sample preparation and extraction were carried out according to Food Standards 2-16721, and the nitrate measurements were performed using ion chromatography (Compact IC Plus 882 Model, Metrohm, Switzerland). A health risk assessment was performed using the non-carcinogenic risk assessment. RESULTS: This study's results showed that the nitrate concertation in all vegetables was less than National Iranian Vegetable Nitrate Standard. Nitrate levels in leafy vegetables were higher than in root vegetables, and the root vegetables levels were higher than those in Fruit vegetable. The nitrate level in vegetables in autumn was higher than in spring. The cooking process reduced the raw vegetables' nitrate content from 4.094% to 13.407%, while the frying process increased the vegetables' nitrate content from 12.46% to 29.93%. The highest health risk level in raw, cooked and fried vegetables was parsley, parsley and beet leaves, respectively, and the lowest in all categories was tomatoes. Generally, the highest health risk was related to fried beet leaves, and the lowest was raw tomatoes. In addition, each of the abovementioned relationships between vegetables' nitrate levels and the harvest season, type of processing procedure and type of vegetables was significant (p < 0.05). The irrigation water's nitrate concentration in all fields was between 12.36 and 33.14 mg/l. The soil contained nitrate levels of between 4.35 and 9.7 mg/kg. CONCLUSION: Based on this study, we can conclude that the amount of nitrates in raw vegetables was lower than the standard limit's level and that this level does not cause health problems for consumers.

Effects of doping zinc oxide nanoparticles with transition metals (Ag, Cu, Mn) on photocatalytic degradation of Direct Blue 15 dye under UV and visible light irradiation.

BACKGROUND: Azo dyes represent the most commonly used group of dyes in the textile industry. These organic dyes are mainly resistant to biodegradation and may exhibit toxic and carcinogenic properties. The purpose of this study was to investigate the effects of doping zinc oxide (ZnO) nanoparticles (NPs) with transition metals (silver, manganese, and copper) on the photocatalytic efficiency of ZnO NPs in the removal of Direct Blue 15 dye from aqueous environments under ultraviolet (UV) radiation and visible light irradiation. METHODS: One or two metals were used for doping the NPs. In total, seven types of undoped and transition metal-doped NPs were synthesized using the thermal solvent method with ZnO precursors and transition metal salts. The characteristics of the synthesized NPs were determined based on the scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), atomic force microscopy (AFM), and zeta potential measurements. RESULTS: The produced ZnO NPs did not exhibit any particular photocatalytic activities under UV radiation and visible light irradiation. The highest removal efficiency under UV radiation was about 74% in the presence of silver-doped ZnO NPs, while the maximum efficiency under visible light was 70% in the presence of copper-doped ZnO NPs. The lowest removal efficiency was related to pure ZnO, which was 18.4% and 14.6% under UV and visible light irradiation, respectively. Although the efficiency of dye removal under visible light was not high compared to UV radiation, this efficiency was noteworthy in terms of both practical and economic aspects since it was achieved without the presence of ultraviolet radiation. CONCLUSIONS: The synthesis of transition metal-doped ZnO nanophotocatalysts (with one or two metals) under UV radiation or visible light irradiation could be used as an efficient and promising technology for the photocatalytic removal of Direct Blue 15 dye from aqueous environments.

Application of cadmium-doped ZnO for the solar photocatalytic degradation of phenol.

In this study, photocatalysis of phenol was studied using Cd-ZnO nanorods, which were synthesized by a hydrothermal method. The Cd-ZnO photocatalyst was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and Fourier transform infrared (FT-IR) and UV-Vis spectroscopy. XRD patterns exhibit diffraction peaks indexed to the hexagonal wurtzite structures with the P63mc space group. SEM images showed that the average size of the Cd-ZnO nanorods was about 90 nm. Moreover, the nanorods were not agglomerated and were well-dispersed in the aqueous medium. FT-IR analysis confirmed that a surface modifier (n-butylamine) did not add any functional groups onto the Cd-ZnO nanorods. The dopant used in this study showed reduction of the bandgap energy between valence and conduction of the photocatalyst. In addition, effect of various operational parameters including type of photocatalyst, pH, initial concentration of phenol, amount of photocatalyst, and irradiation time on the photocatalytic degradation of phenol has been investigated. The highest phenol removal was achieved using 1% Cd-ZnO for 20 mg/l phenol at pH 7, 3 g/l photocatalyst, 120 min contact time, and 0.01 mole H2O2.

Concentration, Source, and Potential Human Health Risk of Heavy Metals in the Commonly Consumed Medicinal Plants.

A trend toward the use of traditional and herbal medicines has developed nowadays, and there is a growing concern regarding them being polluted with heavy metals. This study measured the heavy metal concentrations in eight different types of medicinal herbs and eight different types of herbal distillates sold in the markets in Sanandaj, Kurdistan, Iran. The concentration of some metals (Cd, Cu, Mn, Fe, Zn, Al, Co, Ni, Cr, Pb, and Mg) was quantified by inductively coupled plasma mass spectrometry, and the associated health risk for adults and children was estimated. The mean concentration of all the metals was within the permissible limits set by the WHO. The medicinal herbs contained significantly more Al, As, Cd, Cr, Fe, Mn, Ni, Pb, and Zn (p < 0.02) than the herbal distillates. However, the concentrations of Cu and Hg were higher in the herbal distillates. The non-carcinogenic risks of consumption of traditional medicines in adults and children were assessed based on the target hazard quotients (THQs). The THQs for individual metals (except Al and Cr) from individual herbs were less than 1, which is considered as safe for human consumption.

Land aptitude for horticultural crops and water requirement determination under unsustainable water resources condition.

Droughts and pressure on soil and water resources in arid climatic condition call for integrated managements of existing resources. In this research, the sustainability of water resources was analyzed and an agricultural land potential assessment and water demand determination model were proposed. The capabilities of the model were illustrated with sample results for basins at the Kurdistan Province, Iran. The long-term meteorological, climate, hydrometric, and synoptic data were analyzed. The climate zones and annual water potential at each basin were derived. Appropriate maps were extracted in GIS environment to assess the agricultural land capability and crop adaption. The data from synoptic stations was used to obtain crop water requirement by CROPWAT software and FAO guidelines. The results showed that the rainfall and runoff in the study area were affected by climate changes, and in some basins, result shows severe drop. The results of proposed model indicated that diversity and quality of lands with the potential for development in the study area were substantial, and the agricultural lands can be expanded hugely. Considering the unsustainability in water resources, the annual water rate of the basins cannot meet the water demands of land development. The proposed model provides an integrated framework for the application of water management strategies in integrated water resources management.

Predicting vitamin E and C consumption intentions and behaviors among factory workers based on protection motivation theory.

BACKGROUND: Study of antioxidant vitamin consumption behavior, especially in high-risk groups with high exposure to toxic metals to reduce metal toxicity, is emphasized. This study aims to examine the structural relationships between knowledge, protection motivation theory constructs, and vitamin E and C consumption behavior among cement factory workers. METHODS: Protection motivation theory and food frequency questionnaires were completed by 420 factory workers. Data were subjected to structural equation modeling to examine associations between knowledge, protection motivation theory constructs, and vitamin E and C consumption behavior. Efficacy of current recommended models was also explored. RESULTS: Structural equation modeling showed high explained variance within the constructs of protection motivation theory for vitamin E and C consumption behavior and intention (56-76%). The overall fit of the structural models was acceptable for both vitamin E and C behavior. Knowledge, self-efficacy, response efficacy, and perceived vulnerability predicted intention, which in turn predicted vitamin consumption behavior. Significant relationships between knowledge and self-efficacy, response efficacy, perceived vulnerability, and perceived severity were also found, while self-efficacy and response efficacy showed significant relationships with vitamin E and C consumption behavior. CONCLUSIONS: Considering that response efficacy, self-efficacy, and intention showed as strong predictors of vitamin E and C consumption behavior, specific attention should be paid to coping appraisals and intention when designing intervention plans. Additionally, establishing the predicting role of knowledge for protection motivation theory constructs and protective behaviors should be integrated into intervention programs.

Prevalence of Intestinal Protozoa Infections and Associated Risk Factors among Schoolchildren in Sanandaj City, Iran.

BACKGROUND: Intestinal parasites are still a serious public health problem in the world, especially in developing countries. This study aimed to assess the prevalence of intestinal protozoa infections and associated risk factors among schoolchildren in Sanandaj City, Iran. METHODS: This cross-sectional study involving 400 schoolchildren was carried out in 2015. Each student was selected using systematic random sampling method. Questionnaire and observation were used to identify possible risk factors. Fresh stool samples were observed using formal-ether concentration method. RESULTS: Five species of intestinal protozoa were identified with an overall prevalence of 42.3%. No cases of helminthes infection were detected. The predominant protozoa were Blastocys hominis (21.3%) and Entamoeba coli (4.5%). Overall, 143 (35.9%) had single infections and 26 (6.4%) were infected with more than one intestinal protozoa, in which 23 (5.9%) had double intestinal protozoa infections and 3 (0.5%) had triple infections. A significant relationship was observed between intestinal protozoa infection with economic status, water resources for drinking uses, and the methods of washing vegetables (P<0.05). CONCLUSION: Education programs on students and their families should be implemented for the prevention and control of protozoa infections in the study area.

Evaluation of trace element concentration in cancerous and non-cancerous tissues of human stomach.

Gastric cancer has a high mortality rate in west of Iran. Various environmental elements are proposed as cancer risk factors including trace elements. Trace elements can induce initiation or progression of carcinogenesis via oxidative stress and DNA injury. The aim of this study was to measure and compare some trace element concentration (Ca, Cu, Fe, As, Mg, Ni, Cd and Cr) in gastric cancer tissues and normal tissues. For this purpose, 35 patients with gastric cancer and 30 without any cancer were biopsied. Biopsies were taken from cancerous tissue and non-cancerous tissue of gastric cancer patients and gastric tissue of normal patients. The analysis of trace elements was performed using Inductively coupled plasma mass spectrometry (ICP-MS). Data analysis was carried out using SPSS and STATA 12 software. The research found that the concentrations of Fe, Mg, and As were higher in cancerous tissues compared with non-cancerous tissues whereas Cr, Cu, Ca, and Ni concentrations were higher in non-cancerous tissues of cancerous patients. When comparisons were made for cancer and normal samples, copper was the only metal, which was significantly higher in cancerous samples (p < 0.05) and Cr mean concentration in normal tissues was significantly higher compared with cancerous tissues (P = 0.02). Chi-Square test showed that there was no significant relationship in the demographic information between cancerous and normal patients except for location with K2 = 7.604. Increased Cu and As concentration in gastric patients (both tissues) propose that these elements may have carcinogenic effects, although further study is suggested.

Decontamination of arsenic(V)-contained liquid phase utilizing Fe3O4/bone char nanocomposite encapsulated in chitosan biopolymer.

The application of a novel nanocomposite synthesized through the combination of Fe3O4 nanoparticles and bone char particles for the adsorption of As(V) ions in the aquatic medium was investigated. As-prepared nanocomposite was immobilized by using chitosan biopolymer. The characterization of the nanocomposite was performed via SEM, XRD, FT-IR, and BET together with the determination of zero-point charge of the adsorbent surface. As results, the obtained experimental data were fitted well with pseudo-first-order kinetic model (R2 = 0.997) and Langmuir isotherm model (R2 = 0.990) with the maximum adsorption capacity of about 112 µg/g. Increasing the dosage of nanocomposite and initial solute concentration led to increasing the adsorption capacity of As(V) ions, while decreasing the solution temperature resulted in the enhanced adsorption process. According to the results of thermodynamic study, the adsorption of As(V) ions onto the nanocomposite was spontaneous and exothermic in nature.

Photocatalytic degradation of Aniline from aqueous solutions under sunlight illumination using immobilized Cr:ZnO nanoparticles.

The present study aimed at synthesizing chromium doped zinc oxide nanoparticles (Cr:ZnO NPs) under mild hydrothermal conditions (temperature ~100 °C, p = autogenous and time ~12 hr). Chromium oxide and n-butylamine were used as dopant and surface modifier, respectively. The characteristics of the synthesized nanoparticles were determined through conducting specialized experiments including powder XRD, FTIR, SEM, EDX, and UV-VIS spectroscopy. Then, the Cr:ZnO NPs were immobilized on a sandblasted glass through thermal method. The photocatalytic degradation of aniline was conducted in a continuous reactor with a volume of 1.5 liters. Before and after photocatalytic degradation, the immobilized Cr:ZnO NPs were characterized for SEM and EDX to determine the degree of stability of immobilized nanoparticles as well as the influence of the current applied on them. The photodegradation operational parameters investigated were aniline initial concentration (150, 200, and 250 mg/L), pH (5, 7, 6, and 12), and reaction time (2, 4, and 6 hours) under sunlight illumination. The characterization results indicated high purity of the Cr:ZnO NPs and no change in morphology or composition even after the immobilization and photo-oxidation process. Finally, it was found that the optimum conditions for 93% removal of aniline under sunlight illumination was about 6 hours retention time at pH 9.

Isolation and identification of indigenous prokaryotic bacteria from arsenic-contaminated water resources and their impact on arsenic transformation.

Arsenic is a known human carcinogen. Arsenite [As(III), H3AsO3] and arsenate [As(V), H2AsO4- and HAsO42-] are the two predominant compounds of As found in surface water and groundwater. The aim of this study was to explore a bioremediation strategy for biotransformation of arsenite to arsenate by microorganisms. In this study, Babagorgor Spring, located west of Iran, was selected as the arsenic-contaminated source and its physicochemical characteristics and in situ microbiological composition were analyzed. Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) analysis indicated that the arsenic level was 614µg/l. Fourteen arsenic tolerant indigenous bacteria were isolated from arsenic-contaminated water using chemically defined medium (CDM), supplemented with 260-3900mg/l arsenite and 1560-21800mg/l arsenate. Among the isolates, a strain As-11 exhibited high ability of arsenic transformation. Biochemical tests were used for bacterial identification and confirmation was conducted by 16S rRNA sequence analysis. Results confirmed that As-11 was related to the genus Pseudomonas. This bacterium showed maximum tolerable concentration to arsenite up to 3250mg/l and arsenate up to 20280mg/l. Under heterotrophic conditions, the bacterium exhibited 48% of As(III) and 78% of As(V) transformation from the medium amended with 130 and 312mg/l of sodium arsenite and sodium arsenate, respectively. Moreover, under chemolithotrophic conditions, bacterium was able to transform 41% of 130mg/l of As(III) from the medium amended with nitrate as the terminal electron acceptor. Pseudomonas strain As-11 was reported as an arsenic transformer, for the first time.

Copper Bioaccumulation and Depuration in Common Carp (Cyprinus carpio) Following Co-exposure to TiO2 and CuO Nanoparticles.

Metal oxide nanoparticles (NPs), such as TiO2 and CuO, are widely applied in an increasing number of products and applications, and therefore their release to the aquatic ecosystems is unavoidable. However, little is known about joint toxicity of different NPs on tissues of aquatic organisms, such as fish. This study was conducted to assess the uptake and depuration of Cu following exposure to CuO NPs in the presence of TiO2 NPs in the liver, intestine, muscle, and gill of common carp, Cyprinus carpio. Carps with a mean total length of 23 ± 1.5 cm and mean weight of 13 ± 1.3 g were divided into 6 groups of 15 each (1 control group) and exposed to TiO2 NPs, CuO NPs, and a mixture of TiO2 and CuO NPs for periods of 20 days for uptake and 10 days for depuration. The determination of total Cu concentration was carried out by an ICP-OES. The order of Cu uptake in different tissues of the carps was liver > gill > muscle > intestine in both levels of CuO NPs alone; results showed that the total Cu concentrations in the presence of TiO2 nanoparticles were increased and were in the sequence of liver > gill > intestine > muscle. In depuration period, Cu concentrations were decreased in all treatments in the sequence of gill > intestine > muscle > liver. Uptake of Cu in different tissues of common carp increased with increasing concentration and time and was tissues- and time-dependent. In conclusion, this study suggested that the uptake of Cu in the tissues of common carp increased in the joint presence of TiO2 NPs.

Histopathological effects following short-term coexposure of Cyprinus carpio to nanoparticles of TiO2 and CuO.

The aim of this research was to investigate the coexposure of nanoparticles of titanium dioxide (TiO2) and copper oxide (CuO) on the alterations of the gill, intestine, kidney, and liver tissues of carps (Cyprinus carpio). In this study, carps (length 23 ± 1.5 cm; weight 13 ± 1.3 g) were divided into six groups of 15 each and exposed to 2.5 and 5.0 mg L(-1) of CuO nanoparticles (NPs), 10.0 mg L(-1) of TiO2 NPs, and 2.5 and 5.0 mg L(-1) of CuO NPs + 10.0 mg L(-1) of TiO2 NP mixture. Fish were sampled for histopathological studies after hematoxylin-eosin staining. Results indicated that the more kinds of histopathology anomalies observed with CuO NP and TiO2 NP mixture were broadly of the same type as CuO NPs and TiO2 NPs alone, but the severity or incidence of injuries of gill, intestine, liver, and kidney of carps in the mixture of CuO NPs + TiO2 NPs was higher than that of each NP alone. Moreover, behavioral changes in carps exposed to CuO NP and TiO2 NP mixture such as hyperactivity, loss of balance, and convulsions were higher than those to CuO NPs and TiO2 NPs alone. In conclusion, the presence of TiO2 NPs enhanced the effects of NPs of copper oxide in terms of histopathological changes in carps.

Visual Display Terminal use in Iranian bank tellers: Effects on job stress and insomnia.

BACKGROUND: Visual Display Terminals (VDTs) are equipments in many workplaces which their use may increase the risk of visual, musculoskeletal and mental problems including insomnia. OBJECTIVE: To determine the relationship between duration of daily VDT use and insomnia among the Iranian bank tellers. METHODS: We randomly selected 382 bank tellers working with VDT. Quality of sleep and stress information were collected by Athens Insomnia Scales (AIS) and Demand-Control Model (DCM) model respectively. RESULTS: Out of 382 participants, 127 (33.2%) had sleep complaints and 255 (66.8%) had no sleep disorders. Moreover, the insomnia symptoms' score were significantly high in the participants having more than 6 hours of daily VDT use after adjusting for multiple confounding factors (P <  0.001). There was no significant relationship between stress and insomnia. CONCLUSIONS: It seems that the low levels of stress and job satisfaction reduce the impact of VDT on sleep quality in tellers who worked less than 6 hours per day.

Determination of the Concentration and Composition of PM10 during the Middle Eastern Dust Storms in Sanandaj, Iran.

BACKGROUND: The present study investigated the effect of the Middle East dust storm episodes on the concentration and composition of PM10 during April to September 2013 in Sanandaj City, western Iran. METHODS: Sampling was once every six days, and on dusty days using an Omni air sampler. The PM10 sample was collected on polytetrafluoroethylene filters. Average of 24 h values of PM10 mass concentrations was determined. Half of each sample filter and blank filter was analyzed for water -soluble ions and the other half was digested for metal analysis. RESULTS: The average PM10 concentration was 160.63 µg/m3. The lowest and highest concentrations of PM10 were in May and June respectively. The average PM10 concentration during the non-dusty days was 96.88 (µg /m3). Nevertheless, it increased by 4.8 times during the dusty days. Ca2+, Cl-, NO3-, and Na+ accounted for 71% of total water-soluble ions on the dusty days. During the dusty days, the dominant elements in PM10 were Na, Ca, Mg, Al, and Fe contributing to 95.72% of total measured metals. The correlation coefficient and enrichment factor analysis have shown that on dusty days, Al, Ca, Fe, K, Mg, Na, Sr, and V were the elements with the crustal sources. CONCLUSIONS: Concentrations of PM10 during dusty days were considerably higher than that during non-dusty days. In addition, concentrations of water-soluble ions and metals were also higher during dusty days.