Phototrophic Nitrogen Fixation, a Neglected Biogeochemical Process in Mine Tailings?

Biological nitrogen fixation (BNF) has important ecological significance in mine tailing by contributing to the initial accumulation of nitrogen. In addition to chemolithotrophic and heterotrophic BNF, light may also fuel BNF in oligotrophic mine tailings. However, knowledge regarding the occurrence and ecological significance of this biogeochemical process in mine tailings remains ambiguous. The current study observed phototrophic BNF in enrichment cultures established from three primary successional stages (i.e., original tailings, biological crusts, and pioneer plants) of tailings. Notably, phototrophic BNF in tailings may be more active at vegetation stages (i.e., biological crusts and pioneering plants) than in bare tailings. DNA-stable isotope probing identified Roseomonas species as potential aerobic anoxygenic phototrophs responsible for phototrophic BNF. Furthermore, metagenomic binning as well as genome mining revealed that Roseomonas spp. contained essential genes involved in nitrogen fixation, anoxygenic photosynthesis, and carbon fixation, suggesting their genetic potential to mediate phototrophic BNF. A causal inference framework equipped with the structural causal model suggested that the enrichment of putative phototrophic diazotrophic Roseomonas may contribute to an elevated total nitrogen content during primary succession in these mine tailings. Collectively, our findings suggest that phototrophic diazotrophs may play important roles in nutrient accumulation and hold the potential to facilitate ecological succession in tailings.

Microbial Sulfur and Arsenic Oxidation Facilitate the Establishment of Biocrusts during Reclamation of Degraded Mine Tailings.

Degraded tailings generated by the mining of metal ores are major environmental threats to the surrounding ecosystems. Tailing reclamation, however, is often impeded due to adverse environmental conditions, with depleted key nutrients (i.e., nitrogen (N) and phosphorus (P)) and elevated sulfur and metal(loid) concentrations. Formation of biocrusts may significantly accelerate nutrient accumulation and is therefore an essential stage for tailing reclamation. Although suggested to play an important role, the microbial community composition and key metabolisms in biocrusts remain largely unknown and are therefore investigated in the current study. The results suggested that sulfur and arsenic oxidation are potential energy sources utilized by members of predominant biocrust bacterial families, including Beijerinckiaceae, Burkholderiaceae, Hyphomicrobiaceae, and Rhizobiaceae. Accordingly, the S and As oxidation potentials are elevated in biocrusts compared to those in their adjacent tailings. Biocrust growth, as proxied by chlorophyll concentrations, is enhanced in treatments supplemented with S and As. The elevated biocrust growth might benefit from nutrient acquisition services (i.e., nitrogen fixation and phosphorus solubilization) fueled by microbial sulfur and arsenic oxidation. The current study suggests that sulfur- and arsenic-oxidizing microorganisms may play important ecological roles in promoting biocrust formation and facilitating tailing reclamation.

Ageism and lookism as stereotypes of health disparity in intensive care units in Iran: a critical ethnography.

BACKGROUND: The intensive care unit presents structural complexities, and the prevailing power imbalance between patients and staff can lead to health disparities. Hence, unveiling the underlying factors that give rise to and reinforce these disparities can contribute to their prevention. This study aims to shed light on the stereotypes linked to ageism and lookism, which perpetuate health disparities within the intensive care unit setting in Iran. METHODS: This critical ethnographic study employed Carsepkan's approach and was carried out in intensive care units in the west of Iran from 2022 to 2023. The data collection and analysis were conducted through three interconnected stages. In the initial stage, more than 300 h of observations were made at the research site. In the subsequent stage, a horizon analysis was performed. Conversations with 14 informants were conducted in the final stage to enrich the dataset further. Then the analysis process was carried out as in the previous step to uncover an implicit culture of health disparity. To verify the validity and reliability of the study, credibility, conformability, dependability, and transferability were all taken into account. FINDINGS: The ageism and lookism stereotypes emerged from seven main themes; youth-centric; negative ageism; age-friendliness; age-related priority; centered care for pediatric patients and families; appearance-centeredness; and a contradiction between belief and behavior. CONCLUSION: This critical study showed that ageism and lookism stereotypes permeated the intensive care unit's culture. These stereotypes have the potential to influence equality dynamics, as well as to foster and support health disparity in the intensive care unit.

The efficacy of virtual reality for upper limb rehabilitation in stroke patients: a systematic review and meta-analysis.

BACKGROUND: Stroke frequently gives rise to incapacitating motor impairments in the upper limb. Virtual reality (VR) rehabilitation has exhibited potential for augmenting upper extremity recovery; nonetheless, the optimal techniques for such interventions remain a topic of uncertainty. The present systematic review and meta-analysis were undertaken to comprehensively compare VR-based rehabilitation with conventional occupational therapy across a spectrum of immersion levels and outcome domains. METHODS: A systematic search was conducted in PubMed, IEEE, Scopus, Web of Science, and PsycNET databases to identify randomized controlled trials about upper limb rehabilitation in stroke patients utilizing VR interventions. The search encompassed studies published in the English language up to March 2023. The identified studies were stratified into different categories based on the degree of immersion employed: non-immersive, semi-immersive, and fully-immersive settings. Subsequent meta-analyses were executed to assess the impact of VR interventions on various outcome measures. RESULTS: Of the 11,834 studies screened, 55 studies with 2142 patients met the predefined inclusion criteria. VR conferred benefits over conventional therapy for upper limb motor function, functional independence, Quality of life, Spasticity, and dexterity. Fully immersive VR showed the greatest gains in gross motor function, while non-immersive approaches enhanced fine dexterity. Interventions exceeding six weeks elicited superior results, and initiating VR within six months post-stroke optimized outcomes. CONCLUSIONS: This systematic review and meta-analysis demonstrates that adjunctive VR-based rehabilitation enhances upper limb motor recovery across multiple functional domains compared to conventional occupational therapy alone after stroke. Optimal paradigms likely integrate VR's immersive capacity with conventional techniques. TRIAL REGISTRATION: This systematic review and meta-analysis retrospectively registered in the OSF registry under the identifier [ https://doi.org/10.17605/OSF.IO/YK2RJ ].

Exploring the geospatial epidemiology of breast cancer in Iran: identifying significant risk factors and spatial patterns for evidence-based prevention strategies.

BACKGROUND: Breast Cancer (BC) is a formidable global health challenge, and Iran is no exception, with BC accounting for a significant proportion of women's malignancies. To gain deeper insights into the epidemiological characteristics of BC in Iran, this study employs advanced geospatial techniques and feature selection methods to identify significant risk factors and spatial patterns associated with BC incidence. METHODS: Using rigorous statistical methods, geospatial data from Iran, including cancer-related, sociodemographic, healthcare infrastructure, environmental, and air quality data at the provincial level, were meticulously analyzed. Age-standardized incidence rates (ASR) are calculated, and different regression models are used to identify significant variables associated with BC incidence. Spatial analysis techniques, including global and local Moran's index, geographically weighted regression, and Emerging hotspot analysis, were utilized to examine geospatial patterns, identify clustering and hotspots, and assess spatiotemporal distribution of BC incidence. RESULTS: The findings reveal that BC predominantly affects women (98.03%), with higher incidence rates among those aged 50 to 79. Isfahan (ASR = 26.1) and Yazd (ASR = 25.7) exhibit the highest rates. Significant predictors of BC incidence, such as marriage, tertiary education attainment rate, physician-to-population ratio, and PM2.5 air pollution, are identified through regression models. CONCLUSION: The study's results provide valuable information for the development of evidence-based prevention strategies to reduce the burden of BC in Iran. The findings underscore the importance of early detection, health education campaigns, and targeted interventions in high-risk clusters and adjacent regions. The geospatial insights generated by this study have implications for policy-makers, researchers, and public health practitioners, facilitating the formulation of effective BC prevention strategies tailored to the unique epidemiological patterns in Iran.

Chemolithotrophic Biological Nitrogen Fixation Fueled by Antimonite Oxidation May Be Widespread in Sb-Contaminated Habitats.

Nitrogen (N) deficiency in mining-contaminated habitats usually hinders plant growth and thus hampers tailing revegetation. Biological N fixation (BNF) is an essential biogeochemical process that contributes to the initial accumulation of N in oligotrophic mining-contaminated regions. Previous studies reported that chemolithotrophic rather than heterotrophic diazotrophs frequently dominated in the mining-contaminated regions. Chemolithotrophic diazotrophs may utilize elements abundant in such habitats (e.g., sulfur (S), arsenic (As), and antimony (Sb)) as electron donors to fix N2. BNF fueled by the oxidation of S and As has been detected in previous studies. However, BNF fueled by Sb(III) oxidation (Sb-dependent BNF) has never been reported. The current study observed the presence of Sb-dependent BNF in slurries inoculated from Sb-contaminated habitats across the South China Sb belt, suggesting that Sb-dependent BNF may be widespread in this region. DNA-stable isotope probing identified bacteria associated with Rhodocyclaceae and Rhizobiaceae as putative microorganisms responsible for Sb-dependent BNF. Furthermore, metagenomic-binning demonstrated that Rhodocyclaceae and Rhizobiaceae contained essential genes involved in Sb(III) oxidation, N2 fixation, and carbon fixation, suggesting their genetic potential for Sb-dependent BNF. In addition, meta-analysis indicated that these bacteria are widespread among Sb-contaminated habitats with different niche preferences: Rhodocyclaceae was enriched in river sediments and tailings, while Rhizobiaceae was enriched only in soils. This study may broaden our fundamental understanding of N fixation in Sb-mining regions.

Cultural competence in critical care nurses and its relationships with empathy, job conflict, and work engagement: a cross-sectional descriptive study.

BACKGROUND: Cultural competence is more important than ever for nurses today; therefore, it may be helpful to learn more about it and examine how it relates to empathy, job conflict, and work engagement. The purpose of this study was to determine (a) the level of cultural competence, empathy, job conflict, and work engagement; (b) the relationship between cultural competence, demographic information, and main variables; (c) the predictors of cultural competence among critical care nurses. METHODS: A multicenter, descriptive cross-sectional study was conducted in Iran from August to October 2022. Through convenience sampling, 153 critical care nurses from three hospitals participated. The research tool consisted of five parts: Demographic information questionnaire, Cultural Competence Questionnaire, Jefferson Scale Empathy, Dobrin Job Conflict, and Utrecht Work Engagement, which were collected by paper self-report. Descriptive statistics, the correlation between variables, and linear regression were used to analyze the data. RESULTS: Among critical care nurses (response rate 79.27%), the mean (SD) scores for cultural competence, empathy, job conflict, and work engagement were 74.05 (7.96), 83.44 (29.17), 11.00 (2.38), and 43.69 (16.33), respectively. There was a significant correlation between cultural competence and age (r = 0.46, p = 0.001), marital status (r = 0.27, p = 0.004), academic degree (r = 0.44, p = 0.001), work experiences (r = 0.43, p = 0.001), empathy (r = 0.50, p = 0.001), and job conflict (r=-0.16, p = 0.049). Academic degree (ß = 0.36, p < 0.001) and empathy (ß = 0.26, p < 0.001) were significant explanatory variables that predict cultural competence. CONCLUSION: In Iranian critical care nurses, cultural competence and job conflict were moderate, empathy was good, and work engagement was poor. There was a significant relationship between cultural competence, age, marital status, academic degree, work experiences, empathy, and job conflict. Academic degree and empathy predict cultural competence.

The effect of a family-based participatory care program on anxiety in patients with acute coronary syndrome in coronary care units: A randomised controlled clinical trial.

BACKGROUND: Admission to the coronary care units (CCUs) and the patient's reduced interaction with family are regarded as important sources of anxiety. Family participation in care programs is pivotal to patient outcomes. OBJECTIVES: The present study was conducted to determine the effect of a care program based on family participation on anxiety in patients with acute coronary syndrome. METHODS: This randomised controlled trial was conducted on 90 patients in CCUs and their families. The patients were randomly assigned to one of the following three groups: routine care, control, and intervention. Routine care measures were provided to the routine care group, increased participation of the family was ensured in the control group, and a family-based participatory care program was implemented in the intervention group with the interaction of the nurse, patient, and family based on five principles, including presence, determination of needs, communication, participation in decision-making, and cooperation in care. The patients' anxiety was measured in the three groups on day 1 and 3 days after the admission to the CCU using the Spielberger State-Trait Anxiety Inventory. RESULTS: The patients' mean state anxiety score before the intervention was 44.4 ± 12.7, 46.6 ± 12.4, and 45.5 ± 12.1 in the routine care, control, and intervention groups, respectively, with no significant differences between them (P = 0.81). After adjusting for anxiety before the intervention and study hospital, the mean (before-after) changes in anxiety score in the three groups showed that anxiety was significantly lower in the intervention group than in the other groups (P < 0.05). CONCLUSION: Increased family presence alone has no effect on the patients' anxiety, but the family's participation and interaction with the care team can affect anxiety levels in cardiac patients in CCUs and improve the care processes. TRIAL REGISTRATION: Iranian Registry of Clinical Trials, Trial No. IRCT201105146481N1.

Evaluating the bio-removal of crude oil by vetiver grass (Vetiveria zizanioides L.) in interaction with bacterial consortium exposed to contaminated artificial soils.

Remediation of crude oil-impacted areas is a major pervasive concern in various environmental conditions. The major aim of this study was to investigate the collaboration of vetiver grass (Vetiveria zizanioides L.) and petroleum hydrocarbon-degrading bacteria to clean up contaminated soils. Vetiver grass and five native bacterial isolates were used in one consortium to remediate contaminated soil by crude oil at various concentrations (2.0, 4.0, 6.0 8.0, 10, and 12.0% woil/wsoil). The presence of isolated bacteria caused a significant (p < 0.05) increment of root-shoot ratio of vetiver in contaminated soils in comparison to non-contaminated soil. The combination of vetiver and bacterial consortium revealed efficient dissipation of more than 30% of low-molecular-weight polycyclic aromatic hydrocarbons (PAHs) and more than 50% of high-molecular-weight PAHs in all crude oil concentrations. The removal of n-alkanes in the simultaneous presence of the bacteria and plant was more than 70.0% at 10.0% of oil concentration, whereas the removals in control were 20.7, 13.7 and 9.2%, respectively. The hydrocarbons dissipation efficiency of applied treatments decreased at 12.0% of contamination. It is concluded that a combination of vetiver grass and the isolated bacteria could be a feasible strategy for remediation of crude oil-polluted soils. Novelty statementDetermination of the responses of vetiver grass under different crude oil concentrations is one of the novelties of the present study, which is helpful for demonstrating plant tolerance on polluted environments. Also, it adds information about the potential of this grass to clean up crude oil-polluted soils solely as well as in the presence of promising selected bacterial strains.

Monitoring, Source Identification and Environmental Risk of Potentially Toxic Elements of Dust in Isfahan Province, Central Iran.

The aim of this study was to identify potentially toxic elements (PTEs) associated with airborne particulate matters (PMs) and their source identification and environmental risk in Isfahan Province, central Iran. Dust samples were collected from various locations included three urban and four rural locations. Results revealed the eastern part of the region as the main source of dust and showed that the highest monthly atmospheric dust deposition was in July (5.53 g m-2). The mean concentrations of Zn, Pb, Cu and Cd were respectively 279, 63, 49 and 0.5 mg kg-1 in dust samples, whereas Cd showed the highest ecological risk index. Dust samples of urban areas showed considerable and very high levels of pollution indices for Pb and Zn, respectively. Among the metals, Zn showed the highest enrichment factor (>5), mainly due to anthropogenic sources. The comprehensive ecological risk index of PTEs revealed the moderate and considerable risk of Isfahan and Najafabad cities, respectively.

Effects of Valsalva Maneuver on Pain and Vasovagal Reaction During the Removing of Femoral Arterial Sheath After Percutaneous Coronary Intervention: A Randomized Controlled Trial.

PURPOSE: The objective of this study was to investigate the effects of the Valsalva maneuver on pain and vasovagal reactions during femoral arterial sheath removal in patients undergoing percutaneous coronary intervention. DESIGN: This study was a randomized controlled trial. METHODS: In this study, 60 patients undergoing elective coronary angioplasty were randomly assigned to the intervention and control groups. After angioplasty, the patients in the intervention group performed the Valsalva maneuver (20-30 mm Hg) for 10 seconds during the sheath removal. Conversely, in the control group, no inspiratory pressure was applied. Before and immediately after the sheath removal, the patients' pain, vital signs, and vasovagal reactions were measured. FINDINGS: The primary characteristics of the patients were similar in the two groups. The patients in the intervention group had significantly lower pain scores during femoral sheath removal compared to the control group (2.33 ± 1.56 vs 5.56 ± 3.08, P < .001). The Valsalva maneuver during femoral sheath removal decreased the patients' heart rate in the intervention group compared to the control group (78.26 ± 12.37 vs 85.46 ± 11.79, P < .001); however, blood pressure and vasovagal reactions were not significantly different. CONCLUSIONS: This study showed that the Valsalva maneuver during femoral arterial sheath removal can reduce the pain severity score, without increasing the incidence of vasovagal reactions.

Spatial and temporal analysis of myocardial infarction incidence in Zanjan province, Iran.

BACKGROUND: Myocardial Infarction (MI) is a major important public health concern and has huge burden on health system across the world. This study aimed to explore the spatial and temporal analysis of the incidence of MI to identify potential clusters of the incidence of MI patterns across rural areas in Zanjan province, Iran. MATERIALS & METHODS: This was a retrospective and geospatial analysis study of the incidence of MI data from nine hospitals during 2014-2018. Three different spatial analysis methods (Spatial autocorrelation, hot spot analysis and cluster and outlier analysis) were used to identify potential clusters and high-risk areas of the incidence of MI at the study area. RESULTS: Three thousand eight hundred twenty patients were registered at Zanjan hospitals due to MI during 2014-2018. The overall age-adjusted incidence rate of MI was 343 cases per 100,000 person which was raised from 88 cases in 2014 to 114 cases in 2018 per 100,000 person-year (a 30% increase, P < 0.001). Golabar region had the highest age-adjusted incidence rate of MI (515 cases per 100,000 person). Five hot spots and one high-high cluster were detected using spatial analysis methods. CONCLUSION: This study showed that there is a great deal of spatial variations in the pattern of the incidence of MI in Zanjan province. The high incidence rate of MI in the study area compared to the national average, is a warning to local health authorities to determine the possible causes of disease incidence and potential drivers of high-risk areas. The spatial cluster analysis provides new evidence for policy-makers to design tailored interventions to reduce the incidence of MI and allocate health resource to unmet need areas.

Toxicity assessment of total petroleum hydrocarbons in aquatic environments using the bioluminescent bacterium Aliivibrio fischeri.

Toxicity monitoring of environmental pollutants especially petroleum hydrocarbons as priority pollutants is an important environmental issue. This study addresses a rapid, sensitive and cost effective method for the detection of total petroleum hydrocarbons (TPHs) using Aliivibrio fischeri bioluminescence inhibition bioassay. At the first step, the optimum conditions including time, pH and temperature for growth of A. fischeri were determined. Then, two methods were used to evaluate the toxicity of petroleum compounds. In the first method, short-term (15 min) and long-term (16 h) toxicity assays were performed. In the second method luminescence kinetics of A. fischeri was investigated during 24 h. The results demonstrated the most appropriate time for the bacterial growth occurred 16 h after inoculation and optimum temperature and pH were found 25 °C and 7, respectively. Short-term and long-term toxicity did not indicate any toxicity for various concentrations of TPHs (30, 50, 110, 160, 220 mg/L). Considering the luminescence kinetics of A. fischeri the long-term assay was introduced as 6 h. The half maximal effective concentration (EC50) was achieved 1.77 mg/L of TPHs. It is concluded that the luminescence kinetics of A. fischeri can be a valuable approach for assessing toxicity of TPHs in aquatic environments.

Bioaccumulation of heavy metals (Hg, Cd and Ni) by sentinel crab (Macrophthalmus depressus) from sediments of Mousa Bay, Persian Gulf.

The presence of heavy metals (HMs) in the environment can increase their risk of transfer to the food chain. The present study was conducted to investigate the bioaccumulation of HMs including Hg, Cd and Ni in soft and hard tissues of sentinel crab (Macrophthalmus depressus Rüppell, 1830) in sediments of Mousa Bay in northwest of the Persian Gulf. The average (mean ± SD) amounts of Hg, Cd and Ni in the sediments were 6.27 ± 3.66, 3.8 ± 1.48 and 71.6 ± 5.09 µg/g, whereas the relevant amounts for soft tissues were 6.16 ± 4.64, 3.3 ± 1.7 and 19.7 ± 3.96 µg/g, and for hard tissues were, 2.9 ± 1.67, 3.5 ± 1.35 and 10.44 ± 3.1 µg/g, respectively. Accordingly, soft tissues of the crab could be suitable bioindicators of Hg and Cd, whereas the hard tissues could be used as Cd bioindicator. Since the bioaccumulation of Ni was the most, it might have a higher risk among the metals to enter the food chain in the region.

Health-related quality of life (HRQoL) in beta-thalassemia major (ß-TM) patients assessed by 36-item short form health survey (SF-36): a meta-analysis.

PURPOSE: The main purpose of this meta-analysis was to evaluate the impact of beta-thalassemia major (BTM) on the health-related quality of life as assessed by the medical outcomes short-form-36 questionnaire (SF-36). METHODS: A systematic literature search was performed on Cochrane library, Web of Science, Scopus, Science Direct, ProQues, Medline/PubMed, Scholar Google until March 17, 2017 to obtain eligible studies. A fixed effect model was applied to summarize the scores of each domain. The radar chart was used to compare the scores of BTM patients with other health conditions. Spearman's correlation analysis and meta-regression were used to explore the related factors. RESULTS: 26 studies were included in this study, which were all reliable to summarize the scores of the SF36. Pooled mean scores of the physical health domains ranged from 52.74 to 74.5, with the GH and PF domains being the lowest and the highest, respectively. Further, the pooled mean scores of the mental health domains varied between 59.6 and 71.11, with the (MH-VT) and SF domains being the maximum and the minimum, respectively. Patients with BTM had a substantially compromised HRQoL in comparison with the general population. CONCLUSION: BTM could adversely affect the HRQoL of patients. Measuring HRQoL should be considered as an essential part of the overall assessment of health status of BTM patients, which would provide valuable clues for improving the management of disease and making decisions on the treatment.

Removal of phenol and phosphate from aqueous solutions using activated carbons prepared from oily sludge through physical and chemical activation.

Preparation and characterization of activated carbons (ACs) from oily sludge by physical and chemical activation using steam, ZnCl2 and FeCl3 were investigated. The characteristics of produced adsorbents were determined by iodine number, Brunauer-Emmett-Teller (BET) equation, Fourier transform infrared spectrometry and scanning electron microscopy analyses. Batch adsorption experiments for phenol and phosphate were performed to evaluate the efficiency of adsorbents. The optimum porous structure of adsorbents with a BET surface area of 1,259 m2 g-1, total pore volume of 1.22 cm3 g-1 and iodine number of 994 mg g-1 was achieved by ZnCl2 activation at 500 °C and impregnation ratio of 1:1. The adsorption data were well fitted to the pseudo-second-order kinetic model (R2>0.99) and Freundlich isotherm (R2>0.99). The maximum adsorption capacity of phenol (238 mg g-1) and phosphate (102 mg g-1) based on the Langmuir model was achieved at pH of 6.0 and adsorbent dose of 1 g L-1. Thermodynamic parameters were negative and showed that adsorption of phenol and phosphate onto the AC was feasible, spontaneous and exothermic. The results suggested that prepared AC was an effective adsorbent for removal of phenol and phosphate ions from the polluted water.

The use of steel slags in the heterogeneous Fenton process for decreasing the chemical oxygen demand of oil refinery wastewater.

The Fenton process is a useful and inexpensive type of advanced oxidation process for industrial wastewater treatment. This study was performed with the aim of using the steel slag as a catalyst in the heterogeneous Fenton process in order to reduce the chemical oxygen demand (COD) of oil refinery wastewater. The effects of various parameters including the reaction time (0.5, 1.0, 2.0, 3.0 and 4.0 h), pH (2.0, 3.0, 4.0, 5.0, 6.0 and 7.0), the concentration of steel slag (12.5, 25.0 and 37.5 g/L), and H2O2 concentration (100, 250, 400 and 500 mg/L) on the Fenton process were investigated. Furthermore, the effect of microwave irradiation on the process efficiency was studied by considering the optimum conditions of the mentioned parameters. The results showed that using 25.0 g/L of steel slag and 250 mg/L H2O2, at pH = 3.0, could reduce COD by up to 64% after 2.0 h. Also, microwave irradiation decreased the time of the process from 120 min to 25 min in the optimum conditions, but it consumed a high amount of energy. It could be concluded that steel slags had a high potential in the treatment of oil refinery wastewater through the Fenton process.

Heavy metals and their source identification in particulate matter (PM2.5) in Isfahan City, Iran.

The presence of heavy metals (HMs) in particulate matters (PMs) particularly fine particles such as PM2.5 poses potential risk to the health of human being. The purpose of this study was to analyze the contents of HMs in PM2.5 in the atmospheric monitoring stations in Isfahan city, Iran, in different seasons between March 2014 and March 2015 and their source identification using principle component analysis (PCA). The samples of PM2.5 were taken using a high volume sampler in 7 monitoring stations located throughout the city and industrial zones since March 2014 to March 2015. The HMs content of the samples was measured using ICP-MS. The results showed that the concentrations of As, Cd and Ni were in a range of 23-36, 1-12, and 5-76ng/m3 at all the stations which exceeded the US-EPA standards. Furthermore, the concentrations of Cr and Cu reached to 153 and 167ng/m3 in some stations which were also higher than the standard levels. Depending on the potential sources of HMs, their concentration in PM2.5 through the various seasons was different. PCA illustrated that the different potential sources of HMs in the atmosphere, showing that the most important sources of HMs originated from fossil fuel combustion, abrasion of vehicle tires, industrial activities (e.g., iron and steel industries) and dust storms. Management and control of air pollution of industrial plants and vehicles are suggested for decreasing the risk of the HMs in the region.

Temperature-Invariant Aqueous Microgels as Hosts for Biomacromolecules.

Immobilization of enzymes on solid supports has been widely used to improve enzyme recycling, enzyme stability, and performance. We are interested in using aqueous microgels (colloidal hydrogels) as carriers for enzymes used in high-temperature reactions. These microgels should maintain their volume and colloidal stability in aqueous media up to 100 °C to serve as thermo-stable supports for enzymes. For this purpose, we prepared poly(N-hydroxyethyl acrylamide) (PHEAA) microgels via a two-step synthesis. First, we used precipitation polymerization in water to synthesize colloidal poly(diethylene glycol-ethyl ether acrylate) (PDEGAC) particles as a precursor. PDEGAC forms solvent swollen microgels in organic solvents such as methanol and dioxane and in water at temperatures below 15 °C. In the second step, these PDEGAC particles were transformed to PHEAA microgels through aminolysis in dioxane with ethanolamine and a small amount of ethylenediamine. Dynamic laser scattering studies confirmed that the colloidal stability of microgels was maintained during the aminolysis in dioxane and subsequent transfer to water. Characterization of the PHEAA microgels indicated about 9 mol % of primary amino groups. These provide functionality for bioconjugation. As proof-of-concept experiments, we attached the enzyme horseradish peroxidase (HRP) to these aqueous microgels through (i) N-(3-(dimethylamino)propyl)-N'-ethylcarbodiimide hydrochloride (EDC) coupling to the carboxylated microgels or (ii) bis-aryl hydrazone (BAH) coupling to microgels functionalized with 6-hydrazinonicotinate acetone (PHEAA-HyNic). Our results showed that HRP maintained its catalytic activity after covalent attachment (87% for EDC coupling, 96% for BAH coupling). The microgel enhanced the stability of the enzyme to thermal denaturation. For example, the residual activity of the microgel-supported enzyme was 76% after 330 min of annealing at 50 °C, compared to only 20% for the free enzyme under these conditions. PHEAA microgels in water show great promise as hosts for enzymatic reaction, especially at elevated temperatures.

Effect of Co-planted Purslane (Portulaca Oleracea L.) on Cd Accumulation by Sunflower in Different Levels of Cd Contamination and Salinity: A Pot Study.

Heavy metal bioaccumulation can be affected by various crop-weed interactions that potentially exist in agroecosystems. A pot experiment was conducted to evaluate the role of rhizosphere interaction of sunflower and purslane (Portulaca oleracea L.) weed on cadmium (Cd) uptake and its allocation to sunflower grains. The experimental treatments consisted of two cropping systems (mono and mixed culture), two adjusted salinity levels (0 and 0.5% NaCl) and three artificial levels of Cd in soil (Control, 3 and 6 mg kg(-1)). The results showed that the growth of sunflower in the presence of purslane in comparison to mono culture of sunflower led to change of total Cd content and Cd allocated to grains only in saline conditions. Promoting effects of salinity on Cd concentration of grain were alleviated where sunflower was co-planted with purslane. Besides, supply of Zn in grains of co-planted sunflower was strongly affected by salinity. Results of this study revealed that although co-planted purslane could alter conditions in the shared rhizosphere, it had no effect on enhancing Cd uptake by neighboring sunflower directly.