6,465 research outputs found

    Modified-nano-adsorbents for nitrate efficient removal: a review

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    Excessive nitrate discharge into the aquatic environment from human activities is the main contributor to groundwater and surface water contamination. Its toxicity in water is a serious concern as it gives huge impacts on aquatic life since it damages the ecosystem and water sources around the globe. Recently, the development of nanomaterials as nano-adsorbent makes adsorption the most attractive solution among them. Nano-adsorbents pose high efficiency to remove pollutants from aqueous media. The exclusive chemical and structural properties of the developed nano-adsorbents are the determinative effects of nitrate adsorption performance. In this mini review, the state-of-the-art development of nano-adsorbents and nano-adsorbents-modified membranes for nitrate from water is discussed, and some challenges faced in this field are also highlighted

    Textile Diamond Dipole and Artificial Magnetic Conductor Performance under Bending, Wetness and Specific Absorption Rate Measurements

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    Textile diamond dipole and Artificial Magnetic Conductor (AMC) have been proposed and tested under wearable and body centric measurements. The proposed antenna and AMC sheet are entirely made of textiles for both the substrate and conducting parts, thus making it suitable for wearable communications. Directive radiation patterns with high gain are obtained with the proposed AMC sheet, hence minimizing the radiation towards the human body. In this study, wearable and body centric measurements are investigated which include bending, wetness and Specific Absorption Rate (SAR). Bending is found not to give significant effect to the antenna and AMC performance, as opposed to wetness that yields severe performance distortion. However, the original performance is retrieved once the antenna and AMC dried. Moreover, notable SAR reduction is achieved with the introduction of the AMC sheet, which is appropriate to reduce the radiation that penetrates into human flesh

    Changing species distribution and antimicrobial susceptibility pattern of Shigella over a 29-year period (1980-2008)

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    We studied changes in species distribution and antimicrobial resistance patterns of Shigella during 1980-2008, using the Diarrhoeal Diseases Surveillance system of Dhaka Hospital of ICDDR,B. In hospitalized patients Shigella prevalence decreased steadily from 8-12% in the 1980s to 3% in 2008. Endemic S. flexneri was the most commonly isolated species (54%). Epidemic S. dysenteriae type 1 had two peaks in 1984 and 1993, but was not found after 2000, except for one case in 2004. The therapeutic options are now limited: in 2008 a total of 33% of S. flexneri were resistant to ciprofloxacin and 57% to mecillinam. In the <5 years age group, severely underweight, wasted and stunted children were more at risk of shigellosis compared to well-nourished children (P<0·001). Although hospitalization for Shigella diarrhoea is decreasing, the high levels of antimicrobial resistance and increased susceptibility of malnourished children continue to pose an ongoing ris

    Combination of Conservative and Interventional Therapy Strategies for Intra- and Extrahepatic Cholangiocellular Carcinoma: A Retrospective Survival Analysis

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    Background. Due to the predominantly advanced stage at the time of diagnosis treatment of cholangiocarcinoma is difficult. Apart from surgical resection, interventional treatment strategies are increasingly used in advanced stage tumours. The aim of the study was a retrospective comparison of the effect of the various forms of treatment on morbidity and mortality. Method. A total of 195 patients, received either chemotherapy or a combination of photodynamic therapy (PDT) or transarterial chemoembolization (TACE) and chemotherapy. Results. The median survival rate for all patients was 15.6 months, 50.8% were still alive 1 year after diagnosis. Patients, who had previously undergone surgery, survived 17.1 months longer than those without surgical treatment (P < .01). Chemotherapy prolonged the survival by 9.2 months (P = .47). Palliative patients under combination of chemotherapy and PDT survived on average 1.8 months longer (P = .28), with chemotherapy and TACE 9.8 months longer (P = .04) compared to chemotherapy alone. Conclusions. It appears that surgical treatment and chemotherapy combined with PDT or TACE may prolong survival

    Impact of an interatrial shunt device on survival and heart failure hospitalization in patients with preserved ejection fraction

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    Aims: Impaired left ventricular diastolic function leading to elevated left atrial pressures, particularly during exertion, is a key driver of symptoms and outcomes in heart failure with preserved ejection fraction (HFpEF). Insertion of an interatrial shunt device (IASD) to reduce left atrial pressure in HFpEF has been shown to be associated with short‐term haemodynamic and symptomatic benefit. We aimed to investigate the potential effects of IASD placement on HFpEF survival and heart failure hospitalization (HFH). Methods and results: Heart failure with preserved ejection fraction patients participating in the Reduce Elevated Left Atrial Pressure in Patients with Heart Failure study (Corvia Medical) of an IASD were followed for a median duration of 739 days. The theoretical impact of IASD implantation on HFpEF mortality was investigated by comparing the observed survival of the study cohort with the survival predicted from baseline data using the Meta‐analysis Global Group in Chronic Heart Failure heart failure risk survival score. Baseline and post‐IASD implant parameters associated with HFH were also investigated. Based upon the individual baseline demographic and cardiovascular profile of the study cohort, the Meta‐analysis Global Group in Chronic Heart Failure score‐predicted mortality was 10.2/100 pt years. The observed mortality rate of the IASD‐treated cohort was 3.4/100 pt years, representing a 33% lower rate (P = 0.02). By Kaplan–Meier analysis, the observed survival in IASD patients was greater than predicted (P = 0.014). Baseline parameters were not predictive of future HFH events; however, poorer exercise tolerance and a higher workload‐corrected exercise pulmonary capillary wedge pressure at the 6 months post‐IASD study were associated with HFH. Conclusions: The current study suggests IASD implantation may be associated with a reduction in mortality in HFpEF. Large‐scale ongoing randomized studies are required to confirm the potential benefit of this therapy

    Transition from Knudsen to molecular diffusion in activity of absorbing irregular interfaces

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    We investigate through molecular dynamics the transition from Knudsen to molecular diffusion transport towards 2d absorbing interfaces with irregular geometry. Our results indicate that the length of the active zone decreases continuously with density from the Knudsen to the molecular diffusion regime. In the limit where molecular diffusion dominates, we find that this length approaches a constant value of the order of the system size, in agreement with theoretical predictions for Laplacian transport in irregular geometries. Finally, we show that all these features can be qualitatively described in terms of a simple random-walk model of the diffusion process.Comment: 4 pages, 4 figure

    Partial Discharge and Breakdown Strength of Plasma Treated Nanosilica/LDPE Nanocomposites

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    Nanocomposites have been actively studied in recent years as an insulating material due to their excellent in electrical, mechanical and thermal properties. Even though, the addition of nanoparticles into polymer matrices showed better performance in relation to partial discharge (PD) and AC breakdown strength tests. However, the introduction of nanoparticles could lead to the formation of agglomeration of the fillers which may nullify the true capabilities of the composites. Therefore, silane coupling agent was introduced for surface functionalization treatment of the nano filler but among the issues associated are toxicity and complexity. In the present study, atmospheric pressure plasma is proposed to enhance the surface functionalization of the nano filler. This proposed method was used to treat the nanosilica (SiO 2 ) surfaces to enhance the interfacial interaction between the host (LDPE) and nano filler. SiO 2 nano filler was added into the LDPE at weight percentages of 1, 3 and 5%. The phase-resolved PD behaviour and Weibull analysis of AC breakdown strength of untreated and plasma-treated LDPE nanocomposites were measured to evaluate the performance of the samples. As results, the plasma treated LDPE nanocomposites experience apparent increments of the PD resistance and AC breakdown strength as compared to the untreated nanocomposites. It is implied that the plasma treatment of nanosilica has contributed to the enhancement of the filler dispersion and eventually reducing the agglomeration

    Psychiatric disorders in Iranian children and adolescents

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    Objective: The aim of the present study was to investigate the epidemiology of psychiatric disorders in children and adolescents in five provinces of Iran: Tehran, Shiraz, Isfahan, Tabriz and Mashhad. Method: In the present study, we selected 9,636 children and adolescents aged 6-18 years through multistage cluster random sampling method from Tehran, Shiraz, Isfahan, Tabriz and Mashhad. We instructed the clinical psychologists to complete the Strengths and Difficulties Questionnaire (SDQ) for the participants, and those who received a high score on SDQ, completed the Persian version of Kiddie-SADS-Present and Lifetime Version (K-SADS-PL). We used descriptive analysis and 95 confidence interval to investigate the relationship between scores of the K- SADS questionnaire and demographic factors . We used one-way ANOVA to test the significant differences among the disorders according to sex, age and province of residence. Results: Based on the results, oppositional defiant disorder (ODD) (4.45) had the highest prevalence of psychiatric disorders in the five provinces and substance abuse and alcohol abuse (0) had the lowest prevalence. In addition, attention deficit hyperactivity disorder (ADHD) had the most prevalence in boys (5.03) and ODD had the most prevalence in girls (4.05). Among the three age groups, 6 to 9 year olds had the highest rates of ADHD (5.69); 10 to 14 and 15 to 18 year olds had the highest rates of ODD (4.32 and 4.37 respectively). Among the five provinces, Tehran and Mashhad allocated the highest rates of ODD; Isfahan and Shiraz had the highest rates of ADHD; and Tabriz had the highest rates of social phobia. Conclusion: The current study revealed that the overall frequency of psychiatric disorders based on Kiddie- SADS-Present and Lifetime Version (K-SADS-PL) was higher than a similar study. Moreover, in this study, among the five provinces, Tehran and Mashhad allocated the highest rates of ODD; Isfahan and Shiraz had the highest rates of ADHD; and Tabriz had the highest rates of social phobia. Therefore, these percentage of psychiatric disorders in Iran lead us toward a greater use of consultation and mental health services

    Morphology of supported polymer electrolyte ultra-thin films: a numerical study

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    Morphology of polymer electrolytes membranes (PEM), e.g., Nafion, inside PEM fuel cell catalyst layers has significant impact on the electrochemical activity and transport phenomena that determine cell performance. In those regions, Nafion can be found as an ultra-thin film, coating the catalyst and the catalyst support surfaces. The impact of the hydrophilic/hydrophobic character of these surfaces on the structural formation of the films has not been sufficiently explored yet. Here, we report about Molecular Dynamics simulation investigation of the substrate effects on the ionomer ultra-thin film morphology at different hydration levels. We use a mean-field-like model we introduced in previous publications for the interaction of the hydrated Nafion ionomer with a substrate, characterized by a tunable degree of hydrophilicity. We show that the affinity of the substrate with water plays a crucial role in the molecular rearrangement of the ionomer film, resulting in completely different morphologies. Detailed structural description in different regions of the film shows evidences of strongly heterogeneous behavior. A qualitative discussion of the implications of our observations on the PEMFC catalyst layer performance is finally proposed
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