Back-to-back Converter Control of Grid-connected Wind Turbine to Mitigate Voltage Drop Caused by Faults

Power electronic converters enable wind turbines, operating at variable speed, to generate electricity more efficiently. Among variable speed operating turbine generators, permanent magnetic synchronous generator (PMSG) has got more attentions due to low cost and maintenance requirements. In addition, the converter in a wind turbine with PMSG decouples the turbine from the power grid, which favors them for grid codes. In this paper, the performance of back-to-back (B2B) converter control of a wind turbine system with PMSG is investigated on a faulty grid. The switching strategy of the grid side converter is designed to improve voltage drop caused by the fault in the grid while the maximum available active power of wind turbine system is injected to the grid and the DC link voltage in the converter is regulated. The methodology of the converter control is elaborated in details and its performance on a sample faulty grid is assessed through simulation

Bacteria Isolated from Urinary Tract Infection among Patients and Determination of the Antibiotic Susceptibility Patterns of the Gram Negative Bacteria in Iran

Background: Escherichia coli (E. coli) is the most frequent infecting organism in acute infection. So, knowledge about the frequency and distribution of urinary tract infection (UTI) is important to improve infection control measures. The aim of this research was to determine the prevalence of bacteria isolated from urinary tract infection (UTI) in patients and determination of the antibiotic susceptibility patterns of the gram negative bacteria.Materials and Methods: This descriptive study was performed in Imam Reza hospital, Tabriz (northwest of Iran) during March 2012 to February 2013. We surveyed 8153 patients, who had clinical manifestations of UTI. 5093 (62.47%) of them were female and 3060 (37.53%) of them male. Urine specimens were cultured for isolation of the microbial agents of UTI. The isolated bacteria were identified using biochemical tests. Disk diffusion susceptibility test was used to determine antimicrobial susceptibility.Results: E. coli (55.38%) was the most common isolated pathogen, followed by Enterobacter spp. (29.61%), Pseudomonas spp. (4.9%), S. aureus (3.21%), Enterococcus spp. (2.3%),  fungi (1.5%) and Klebsiella (0.48%). The sensitivity rates of isolated gram negative bacteria were for Amikacin (95.7%), Nitrofurantoin (91.5%), Gentamicin (64.1%), Ceftizoxim (56.8%), Ciprofloxacin (37.6%), Cotrimoxazole (31.4%) and Nalidixic acid (23.5%).Conclusion: This study showed that the frequency of E. coli and  Enterobacter spp. increases the probability of urinary tract infection. Also this survey indicates the emergence of antibiotic resistant infections in the studied hospital. So, there is a need to improve the effectiveness of integrated infection control programs to control and manage nosocomial infections caused by highly resistant organisms

Iron removal from aqueous solution by alumina nanoparticles coated with polyaniline

Background and Aims: In view of water crisis, effective prevention of water resources contamination is increasingly important. The presence of heavy metals in drinking water at concentrations greater than acceptable limits may result in various adverse health effects. The present study was conducted to evaluate the feasibility of alumina nanoparticles coated with polyaniline for iron removal from aqueous solutions.Materials and Methods: The direct synthesis method was used to cover the polyaniline film on alumina nanoparticles. Batch adsorption studies were performed as a function of contact time, temperature, adsorbent mass and pH. The adsorption isotherms at iron concentrations ranging from 10 to 150 mg/L as well as the reaction kinetics were also investigated.Results: The maximum efficiency of iron removal was found at pH 3, 24 ºC and 120 min contact time. The maximum sorption capacity of coated nano-alumina for Fe(II) removal was also found to be 45.66 mg g-1 at 0.1g of adsorbent mass.Conclusion: Results from this study demonstrated the potential utility of alumina nanoparticles coated with polyaniline showing 83% adsorption ability for iron removal from aqueous solutions.Key words: Alumina nanoparticles, Polyaniline, Adsorption, Iron ion

Sexual and reproductive healthcare needs of Iranian men: A cross-sectional study

Background: The sexual and reproductive health (SRH) needs of men have received little attention in Iran’s healthcare system. Developing appropriate strategies to meet men’s needs requires careful assessment and recognition of their health needs. Objective: The objective of this study is to assess men’s SRH needs and satisfaction with received services. Materials and Methods: This descriptive cross-sectional study was conducted with 1068 adult men aged between 20 and 60 years in Ahvaz in 2014. For obtaining the SRH services needs of men, in addition to the self-reported felt needs, expressed needs and unmet needs, a need assessment was also done using a questionnaire that was developed for the research; its validity and reliability were assessed. Results: The men’s perceived, expressed and unmet needs for SRH services were, priority-wise, screening and diagnosis of male genital cancers (63.3%), receiving contraceptive methods (36%), diagnosis, and treatment of male sexual dysfunction (86.9%), respectively. Preventing sexually transmitted disease/AIDS (72.1%), using contraceptives correctly (39.5%), and resisting peer pressure (86.6%) were, respectively, the first felt, expressed, and unmet skills men needed. The results of multivariate logistical regression showed that there was a significant statistical correlation between men’s SRH needs and their socio-demographic factors (age, marital/educational status, income) (p < 0.05). Key words: Reproductive health, Needs assessment, Men

Discrete-Time Domain Modeling of a High-Power Medium-Voltage Resonant Converter

LLC resonant converters are widely used indiverse industrial applications, due in part to their highefficiency and high power density. In spite of their numerousadvantages, these converters are still considered themost challenging converters from a modeling and controlperspective. Several factors contribute to this complexity,including the nonlinear behavior and different operatingmodes. Therefore, a high-power medium-voltage resonantconverter is modeled in this manuscript, and its dynamicbehavior is investigated. The nonlinear model simulationperformed by MATLAB/Simulink and the electrical circuitsimulation performed by PLECS are then compared toverify the accuracy of the obtained model

A Quadratic Boost Converter Suitable for Fuel Cell-Powered Electric Vehicles

This study presents a non-inverting transformer-lessBoost converter with a higher voltage conversion ratio, resultingin quadratic growth of the output voltage with modest incrementsin the duty cycle rate. The continuous input current of thisconverter simplifies the input filter design and enhances fuelcells’ lifetime and stability. Additionally, compared to existingarchitectures, this converter reduces the voltage and currentstresses on semiconductor components, making it a promisingalternative to other quadratic Boost converters. As a result, thistopology appears to be a viable alternative for the remainingquadratic Boost converters. The inclusion of common-groundswitches, which eliminate the need for additional components forgate driver isolation, is one of the main features that make thistopology distinct. As a result, the converter fabrication cost andsize are reduced. The proposed converter’s steady-state analysis isthoroughly explained. Stresses placed on semiconductor devices.Then, a meaningful comparison between the proposed circuitand its counterparts is provided to understand this converter’sunique attributes

Introduction of Dianthins: A New Promising Horizon Toward Continuous Research on Breast Cancer Bulldozing in Iran

Background: The production and secretion of defense proteins are one of the protective mechanisms exploited by plants against pathogens. The production and secretion of defense proteins are one of the protective mechanisms exploited by plants against pathogens. Ribosome-Inactivating Proteins (RIPs), as the main class of these proteins, are considered to facilitate cancer therapy worldwide, because of the potential anticancer activity. Indeed, some of these proteins have cytotoxic and anticancer properties. Extracted from the carnation (Dianthus caryophyllus), Dianthin inhibits protein synthesis in many different cells.Methods: In this research, the Dianthins was isolated and purified from the leaves of D. caryophyllus, using ion-exchange chromatography column (CM-Sephadex G-50). Subsequently, its cytotoxicity effect on MCF-7 cell line was investigated. The cell cytotoxicity assessment was performed, using 3-(4,5-Dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT), neutral red uptake, and alkaline comet assays at the concentrations of 1.25μg/mL to 10μg/mL of the protein applying the MCF-7 cell line.Results: the toxin induces cell death, mostly via necrosis rather than apoptosis, but in the special range of concentrations.Conclusion: because of the severe side effects of chemotherapy drugs, this toxin can undergo more research as a new drug candidate against breast cancer

Cognitive determinants of weight control by dietary patterns among postmenopausal women with osteoporosis: An application of theory of planned behavior

Background: In this study, we aimed to assess the cognitive determinants of weight control behaviors by dietary patterns among postmenopausal women with osteoporosis. Methods: This cross-sectional study, based on the theory of planned behavior (TPB) was conducted from July to December 2017 among 240 postmenopausal women with osteoporosis in Tabriz, Iran. A validated and reliable TPB-based instrument, namely Weight-CuRB, and the food frequency questionnaire (FFQ) were used. Results: The results of exploratory factor analysis (EFA) indicated three dietary patterns (total variance explained = 24.44%); healthy (n = 71), mixed (n = 78), and western (n = 91). In addition, food items consumed by participants were classified into twenty-two food groups for dietary pattern analysis. In the healthy and western dietary patterns, attitude (β: 0.140, P\u3c 0.001) and subjective norms (SNs) (β: 0.498, P\u3c 0.01) were the only predictors of weight control behavior, respectively. In the women with healthy and western patterns, the TPB-based variables altogether explained 11% and 16% of variations in the behavior, respectively. Among all patients, the TPB-based variables explained 12.2% of variations in weight control behavior, within which SNs were the only significant predictor of the behavior (β = -0.199, P\u3c 0.01). Conclusion: Our findings highlighted the remarkable role of dietary patterns in the associations between weight control and its cognitive determinants. Dietary patterns should be considered while designing weight control educational interventions among women with osteoporosis. In such interventions, promoting SNs and perceived behavioral control (PBC) should be considered as the core strategies to promote the behaviors among the patients who follow an unhealthy diet