50 research outputs found

    The threates on the biodiversity of Bisotun Wildlife Refuge and Bisotun Protected Area (BPA & BWR) in the west region of Iran

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    Reyahi-Khoram M, Rizvandy M, Reyahi-Khoram R. 2014. The threates on the biodiversity of Bisotun Wildlife Refuge and Bisotun Protected Area (BPA & BWR) in the west region of Iran. Biodiversitas 15: 65-72. Nature is necessary for the preservation of species and biodiversity richness; as a result, it has been protected for thousands of years. Bisotun Protected Area and Bisotun Wildlife Refuge (BPA & BWR) with about 95000 hectares is located in Kermanshah province in the west of Iran. The object of this study is to determine the physical properties and analyze the constraints that threaten the BPA & BWR. This research was conducted during the period from May, 2011 to November, 2012 in BPA & BWR. In this research, various animal and plant species were recognized through documentary analysis and also directs field observations. The obtained result indicates that major threates have occurred in biodiversity and ecosystem of BPA & BWR during 1980-2010. During these years, the study area has completely failed and lost some of its biological diversity. Limiting factors that affect wildlife population growth including destruction and conversion of habitats, unauthorized hunting and high frequency presence of animal and human, have influenced the restoration potential of wildlife, the habitats and other conservation areas

    Kinetic study of heavy metal ions removal from aqueous solutions using activated pumice stone

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    Background: The presence of heavy metals in aquatic and terrestrial ecosystems causes harmful effects to living organisms in the environment. This research aimed to determine the potential of activated pumice stone (APS) as a sorbent for the removal of Cd, Cu, and Zn from wastewater. Methods: This research was conducted during 2013 on a laboratory scale. The study was performed using batch experiments with synthetic wastewater having Cd, Cu, and Zn concentrations of 10, 20, 40, and 80 mg/L. Various isotherm models, including Langmuir and Freundlich, were used to evaluate the sorption data. The influence of contact time and amount of sorbent on the removal of Cd, Cu, and Zn from wastewater was studied. All experiments were done at pH = 7 and at room temperature (20 ± 1°C). The solution pH was adjusted using 1N NaOH or 1N HCl solutions, and the pH value was determined by a pH meter. Results: The results showed that the adsorption of Cd, Cu, and Zn approaches equilibrium after about 2 hours, while the rates of removal efficiency for Cd, Cu, and Zn at equilibrium were 91.6%, 91.8%, and 82.9%, respectively. Kinetic studies showed that the sorption of Cd, Cu, and Zn onto APS were fitted to the pseudo-second order kinetic models. Conclusion: The results indicate that the APS is a good choice, because it is a low-cost and effective sorbent. The sorption capacity of APS as a sorbent was considerably affected by the initial concentration of metal ions in the solution and by contact time. Keywords: Adsorption, Aqueous solution, Environment, Heavy metals, Pumic

    Environmental effects of the cold water fish farms effluents on the water quality of Gamasyab River as their main source of water supply in the west of Iran

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    Rainbow trout (Oncorhynchus mykiss) is one of the most-widely cultivated cold fresh water fish in the world. Gamasyab River, with a length of about 200 Km, is one of the longest rivers of Iran. The aim of this research is to determine the effects of trout farm effluents on this river water. From a total of 24 trout farms in the area, four farms were randomly selected and three sampling stations were chosen at each selected farm. Measured water quality parameters were temperature (T), total suspended solids (TSS), total dissolved solid (TDS), dissolved oxygen (DO), pH, five-day biochemical oxygen demand (BOD_5), chemical oxygen demand (COD), ammonia-nitrogen (NH_4-N), nitrate-nitrogen (NO_3-N) and phosphates (PO_4-P). Based on the laboratory analysis, DO in the river water was more than 6 mg/l in all cases. There were significant differences in six variables of T, BOD, COD, NO_3-N, NH_4-N, and TSS of all water samples taken from the second sampling stations between dry and wet season. The DO concentration in Gamasyab River decreased between the water inlet (first stations) and outlet (second stations), but increased in third station. Trout farm effluents had significant impact on the TSS content of the river. This significant increase in TSS concentrations is expected to have occurred due to cleaning or harvesting activities on any of the farms. The results of the study showed that, in all of season, the amount of TSS in the second stations was not equal to the standards of the Department of Environment Protection (40 mg/L) for discharging into river systems

    Review of Hosein Aabad Sugar Factory (HASF) Wastewater and Assessment of its Pollution Load

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    Sugar industry is one of the largest industries in the world. Hosein Abad sugar factory (HASF) is located in Hamadan province of Iran. The aim of this research was to evaluate the quality and quantity of wastewater of the said factory and to estimate the pollution load and its emission factor as prerequisite of the management and environmental pollutions control in the region. Random grab sampling is used in twelve days between October 2010 and March 2011 during peak hours of activity. In this research, nine quality parameters as the key variables are measured to evaluate the quality of wastewater. The obtained results indicate that, the amount of wastewater produced by HASF is about 2740 m3/day. Based on the said results, the average amount of five days Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) in the raw wastewater was 1296 and 2328 mg/l respectively. The results of this research showed that the effluent wastewater of HASF in the present conditions is highly polluted due to inappropriate treating and is not appropriate for artificial recharge use, discharge in rivers and lakes or utilization in agriculture, according to the DoE standards

    Roles of Oxygen Vacancies and Excess Electron Localization on Ceria Surfaces: First Principles Study

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    In this study, we investigate the (111), (110) and (100) surfaces of reduced ceria (CeO2) using density functional theory (DFT) within DFT+U. We examine the process by which oxygen vacancy sites form on CeO2 (111), (110), and (100) surfaces as well as the stability of these sites close to the ceria surface regions. Our calculations demonstrate that electron localizations of the reduced CeO2 on each of these three surface terminations are caused by oxygen vacancies, both surface and subsurface, which results in the emergence of Ce3+ sites. The oxygen vacancy at the surface and subsurface of CeO2 (111) surfaces results in the formation of Ce3+ at the vacancys next-closest neighbor. Ce3+ is formed at the sites closest to the oxygen vacancy sites on CeO2 (100) and CeO2 (110) surfaces. The calculated total density of states (TDOS) of the reduced surfaces displays that the Ce 4 f states are partially occupied and appeared in a new state near the band gap compared to that for the unreduced ceria surfaces. The existence of these new states was found to have a large effect on the nature of ceria. In (111) ceria surface, the material remains semiconductor with a smaller band gap. However, (110) and (100) ceria surfaces become semi-metallic due to the crossing of a new state of the fermi level that converts ceria to become semi- metallic material. Therefore, the conductivity and chemical properties of ceria are expected to be modified by the creation of oxygen vacancy. The reduced ceria expects to catalyze the dissociation of molecules on its surface. The dissociation is assisted by the oxidation of Ce3+ that is generated on reduced ceria surfaces

    Understanding the role of the perivascular space in cerebral small vessel disease

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    Small vessel diseases are a group of disorders that result from pathological alteration of the small blood vessels in the brain, including the small arteries, capillaries and veins. Of the 35-36 million people that are estimated to suffer from dementia worldwide, up to 65% have an SVD component. Furthermore, SVD causes 20-25% of strokes, worsens outcome after stroke and is a leading cause of disability, cognitive impairment and poor mobility. Yet the underlying cause(s) of SVD are not fully understood.Magnetic resonance imaging (MRI) has confirmed enlarged perivascular spaces (PVS) as a hallmark feature of SVD. In healthy tissue, these spaces are proposed to form part of a complex brain fluid drainage system which supports interstitial fluid exchange and may also facilitate clearance of waste products from the brain. The pathophysiological signature of PVS, and what this infers about their function and interaction with cerebral microcirculation, plus subsequent downstream effects on lesion development in the brain has not been established. Here we discuss the potential of enlarged PVS to be a unique biomarker for SVD and related brain disorders with a vascular component. We propose that widening of PVS suggests presence of peri-vascular cell debris and other waste products that forms part of a vicious cycle involving impaired cerebrovascular reactivity (CVR), blood-brain barrier (BBB) dysfunction, perivascular inflammation and ultimately impaired clearance of waste proteins from the interstitial fluid (ISF) space, leading to accumulation of toxins, hypoxia and tissue damage.Here, we outline current knowledge, questions and hypotheses regarding understanding the brain fluid dynamics underpinning dementia and stroke through the common denominator of SVD

    Identification of additional risk loci for stroke and small vessel disease: a meta-analysis of genome-wide association studies

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    BACKGROUND: Genetic determinants of stroke, the leading neurological cause of death and disability, are poorly understood and have seldom been explored in the general population. Our aim was to identify additional loci for stroke by doing a meta-analysis of genome-wide association studies. METHODS: For the discovery sample, we did a genome-wide analysis of common genetic variants associated with incident stroke risk in 18 population-based cohorts comprising 84 961 participants, of whom 4348 had stroke. Stroke diagnosis was ascertained and validated by the study investigators. Mean age at stroke ranged from 45·8 years to 76·4 years, and data collection in the studies took place between 1948 and 2013. We did validation analyses for variants yielding a significant association (at p<5 × 10(-6)) with all-stroke, ischaemic stroke, cardioembolic ischaemic stroke, or non-cardioembolic ischaemic stroke in the largest available cross-sectional studies (70 804 participants, of whom 19 816 had stroke). Summary-level results of discovery and follow-up stages were combined using inverse-variance weighted fixed-effects meta-analysis, and in-silico lookups were done in stroke subtypes. For genome-wide significant findings (at p<5 × 10(-8)), we explored associations with additional cerebrovascular phenotypes and did functional experiments using conditional (inducible) deletion of the probable causal gene in mice. We also studied the expression of orthologs of this probable causal gene and its effects on cerebral vasculature in zebrafish mutants. FINDINGS: We replicated seven of eight known loci associated with risk for ischaemic stroke, and identified a novel locus at chromosome 6p25 (rs12204590, near FOXF2) associated with risk of all-stroke (odds ratio [OR] 1·08, 95% CI 1·05-1·12, p=1·48 × 10(-8); minor allele frequency 21%). The rs12204590 stroke risk allele was also associated with increased MRI-defined burden of white matter hyperintensity-a marker of cerebral small vessel disease-in stroke-free adults (n=21 079; p=0·0025). Consistently, young patients (aged 2-32 years) with segmental deletions of FOXF2 showed an extensive burden of white matter hyperintensity. Deletion of Foxf2 in adult mice resulted in cerebral infarction, reactive gliosis, and microhaemorrhage. The orthologs of FOXF2 in zebrafish (foxf2b and foxf2a) are expressed in brain pericytes and mutant foxf2b(-/-) cerebral vessels show decreased smooth muscle cell and pericyte coverage. INTERPRETATION: We identified common variants near FOXF2 that are associated with increased stroke susceptibility. Epidemiological and experimental data suggest that FOXF2 mediates this association, potentially via differentiation defects of cerebral vascular mural cells. Further expression studies in appropriate human tissues, and further functional experiments with long follow-up periods are needed to fully understand the underlying mechanisms
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