396 research outputs found
Principles and Requirements of Battery Membranes: Ensuring Efficiency and Safety in Energy Storage
This critical review highlights the latest improvements and special features regarding the membrane separators available for lead-acid, alkaline, metal-metal, metal-gas, and metal-ion batteries such as lithium-ion. In the recent years, there has been a surge in the intensive work aimed at developing innovative separators for rechargeable lithium-ion batteries, for example, electric vehicles (EVs), portable electronics and for energy storage in power grid. The separator finds itself in a very important place as it provides physical separation between two electrodes. It also acts as an electrical insulator. This separator is known as an electrolyte gateway which helps the movement of ions during charge/discharge cycles. This review addresses the requirements for battery separators and explains the structure and properties of various types of membrane separators; there are several types of membranes such as microporous membranes, modified microporous membranes, nonwoven mats, composite membranes and electrolyte membranes. Similarly, each type of separator has inherent advantages and disadvantages which in turn directly affects the performance of batteries. This review article systematically deals with the structures and working principle of separators, properties and main requirements and their characterization method of separators, generation, improvements, and function assessments of these separators. Furthermore, this study also enlightens the emerging research path and future prospects. 
Effects of different regimens of PGF2α treatment during postpartum on reproductive performance in dairy cows
O objetivo do presente trabalho foi avaliar os efeitos do tratamento pĂłs-parto precoce com PGF2α sobre o desempenho reprodutivo de vacas leiteiras sincronizadas para reprodução controlada por monta natural apĂłs o perĂodo de espera voluntĂĄrio. Neste experimento, 120 vacas foram distribuĂdas em trĂȘs grupos independentes da presença ou ausĂȘncia de corpo lĂșteo. Vacas no grupo PG-14 foram tratadas com PGF2α a partir do 14o dia pĂłs-parto, vacas do grupo PG-28 foram tratadas com PGF2α a partir do 28o dia pĂłs-parto e as vacas do grupo PG-42 nĂŁo foram tratadas com PGF2α atĂ© o final do perĂodo de espera voluntĂĄrio (d42). ApĂłs o 42o dia pĂłs-parto as vacas dos trĂȘs grupos foram tratadas com PGF2α com intervalos de 14 dias atĂ© a monta natural apĂłs o perĂodo de espera voluntĂĄrio. Os registros dos parĂąmetros reprodutivos incluĂram: dias para o primeiro estro, dias para a primeira cobertura, dias em aberto, serviços por concepção, taxa de concepção, percentagem de animais repetidores de cios e as perdas de gestaçÔes. O tratamento precoce com PGF2α, a partir do 14o dia pĂłs-parto reduziu significativamente os dias para o primeiro estro (34,9 ± 0,74, P < 0,003), dias para a primeira cobertura (62,35 ± 1,53, P < 0,04), dias em aberto (117,23 ± 3,1, P<0,001) e o nĂșmero de serviços por concepção (1,9 ± 0,009, P < 0,02); e o grupo PG-14 apresentou um acrĂ©scimo na taxa de concepção (52,5%, P < 0,05). A proporção da sĂndrome de vacas repetidoras de cios tendeu a ser afetada pelo tratamento com PGF2α a partir do 14o dia pĂłs-parto. A conclusĂŁo obtida foi que o tratamento das vacas com PGF2α a partir do 14o dia pĂłs-parto melhorou o desempenho reprodutivo dos animais.The aim of this study was to evaluate the effects of early postpartum PGF2α treatment on reproductive performance in dairy cows synchronized with targeted breeding and natural mating after voluntary waiting period. In this experiment, 120 cows were assigned to three groups irrespective of presence or absence of luteal tissue. Cows in PG-14 group were treated with PGF2α from day 14 postpartum, cows in PG-28 group were treated with PGF2α from day 28 postpartum and cows in PG-42 group were not treated with PGF2α until the end of voluntary waiting period (d 42). After day 42 postpartum, cows in three groups were treated with PGF2α within 14-day intervals until natural mating after voluntary waiting period. Recorded reproductive parameters included days to first heat, days to first mating, days open, service per conception, conception rate, percentage of repeat breeder animals and pregnancy loss. Early PGF2α treatment from day 14 postpartum significantly decreased days to first estrus (34.9 ± 0.74, P < 0.003), days to first mating (62.35 ± 1.53, P < 0.04), days open (117.23 ± 3.1, P < 0.001) and service per conception (1.9 ± 0.09, P < 0.02); and PG-14 group presented increased conception rate (52.5%, P < 0.05). The proportion of repeat breeder syndrome tended to be affected by treatment with PGF2α from day 14 postpartum. In conclusion, treatment of cows with PGF2α from day 14 postpartum improved reproductive performance.
A comprehensive control system for multi-parallel grid-connected inverters with LCL filter in weak grid condition
Modeling and design of a multivariable control system for multi-paralleled grid-connected inverters with LCL filter
Active Harmonic Compensation and Stability Improvement in High-Power Grid-Connected Inverters Using Unified Power Quality Conditioner
Multifunctional features of grid-connected inverters can be used for harmonic compensation of local load voltage and grid-injected current. But, in high-power grid-connected inverters, there is a challenge due to low switching frequency. On the other hand, simultaneous compensation of local load voltage and grid-injected current harmonics is an important issue in grid-connected inverters. Using a Unified Power Quality Conditioner (UPQC) at the Point of Common Coupling (PPC), an improved active harmonic compensation method is proposed which is appropriate for high-power low-frequency grid-connected inverters. The UPQC operates as a combination of a negative shunt virtual admittance and a negative series virtual impedance at the PCC. It suppresses the disturbances caused by local load variation and grid impedance change. Using a low-power, high-frequency UPQC, local load voltage and grid-injected current harmonics up to higher-order components are simultaneously compensated despite grid impedance changes and nonlinear local load variations. The control system is designed according to the impedance-based stability criterion to ensure the system's stability. The theoretical results are validated using different case study simulations in MATLAB/Simulink software
Assessment of knowledge and practice of pharmacists regarding oral health in Kerman, Iran
BACKGROUND AND AIM: Oral health is an integral part of general health. Between the different medical professions,
pharmacists are one of the groups who encounter patients seeking consultation in the oral health field a lot. Therefore,
this study aimed to assess the knowledge and practice of pharmacists in Kerman, Iran, toward oral health.
METHODS: All pharmacists were invited to participate in the study after being informed about the aims of the study. A
validated questionnaire with six sections including demographic data, oral hygiene behavior of the participants, the
pharmaciesâ specifications and products related to oral health, questions related to knowledge, questions related to
practice, and questions related to the participantsâ assessment were filled out by the participants. The collected data
were analyzed using SPSS software, and descriptive results were presented in tables and charts. The chi-square
statistical tests were used to explore any association between variables.
RESULTS: Data were analyzed for 81 participants. Most of the participants were male and the mean age was 38 ± 10.
The pharmacistsâ mean knowledge of oral health was 6.5 out of 10 which places them in the medium knowledge range.
The performance of pharmacists when encountering oral problems was prescribing analgesics in 79% of cases for tooth
aches. There was no statistically significant difference in the knowledge score between different age and gender groups
(P = 0.500).
CONCLUSION: The results show a medium knowledge of pharmacists on oral health topics. Considering their own desire
plans to train and educate in oral health fields to promote oral health seem necessary.
KEYWORDS: Knowledge and Practice; Pharmacists; Oral Healt
Prognostic investigations of B7-H1 and B7-H4 expression levels as independent predictor markers of renal cell carcinoma.
In order to evaluate the correlation of B7-H4 and B7-H1 with renal cell carcinoma (RCC), we analyzed B7-H1 and B7-H4 expressions and their clinical significance by immunohistochemical method. Our result indicated that B7-H4-positive staining was detected in 58.13Â % of RCC tissues (25 tissues tumors), and there were 18 tissues of patients without detectable B7-H4. Furthermore, 21 cases (48.83Â %) were B7-H1-positive. Positive tumor expressions of B7-H4 and B7-H1 were markedly related to advanced TNM stage (Pâ=â0.001; Pâ=â0.014), high grade (Pâ=â0.001; Pâ=â002), and larger tumor size (Pâ=â0.002; Pâ=â024) in RCC tissues than patients with B7-H4-negative and B7-H1-negative in RCC tissues. The patients with B7-H1 and B7-H4-positive expressions were found to be markedly correlated with the overall survival of the patients (Pâ<â0.05) and tended to have an increased risk of death when compared with negative expression groups. Univariate analysis showed that B7-H4 and B7-H1 expressions, TNM stage, high grade, and tumor size were significantly related to the prognosis of RCC. Furthermore, multivariate analysis showed that B7-H4 and B7-H1 expressions decreased overall survival. The adjusted HR for B7-H1 was 2.83 (95Â % CI 1.210-2.971; Pâ=â0.031) and also was 2.918 (95Â % CI 1.243-3.102; Pâ=â0.006) for B7-H4 that showed these markers were independent prognostic factors in RCC patients. The expressions of B7-H1 and B7-H4 in RCC patients indicate that these markers may be as a predictor of tumor development and death risk. Further investigations can be helpful to confirm B7-H1 and B7-H4 roles as an independent predictor of clinical RCC outcome
An epidemiological survey of psychiatric disorders in Iran
BACKGROUND: The nation-wide epidemiological survey of psychiatric disorders in term of lifetime prevalence is not adequately known in Iran. The prevalence of lifetime psychiatric disorders was estimated among the population of aged 18 and over on gender, age group, educational level, occupational status, marital status, and residential area. METHODS: The subjects were 25,180 individuals selected through a clustered random sampling method. The psychiatric disorders were diagnosed on the bases of Diagnostic and Statistical Manual of Mental Disorders-IV criteria. It is the first study in which the structured psychiatric interview administered to a representative sample of the Iranian population age 18 and over by the 250 trained clinical psychologist interviewers. The data was entered through EPI-Info software twice in an attempt to prevent any errors and SPSS-11 statistical software was also used for analyses. The odds ratios and their confidence intervals estimated by using logistic regression. RESULTS AND DISCUSSION: The prevalence of psychiatric disorders was 10.81%. It was more common among females than males (14.34% vs. 7.34%, P < 0.001). The prevalence of anxiety and mood disorders were 8.35% and 4.29% respectively. The prevalence of psychotic disorders was 0.89%; neuro-cognitive disorders, 2.78% and dissociative disorders, 0.77%. Among mood disorders, major depressive disorder (2.98%) and among anxiety disorders, phobic disorder (2.05%) had the higher prevalence. The prevalence of psychiatric disorders among divorced and separated 22.31%; residents of urban areas 11.77%; illiterates 13.80%; householders 15.48%; unemployed 12.33% that were more than other groups. CONCLUSION: The mental health pattern in Iran is similar to the western countries, but it seems that the prevalence of psychiatric disorders in Iran may be lower than these countries. It is estimated that at least about 7 millions of Iranian population suffer from one or more of the psychiatric disorders. It shows the importance of the role of the psychiatric disorders in providing preventive and management programs in Iran
Post-crash management of road traffic injury victims in Iran. Stakeholders' views on current barriers and potential facilitators
<p>Abstract</p> <p>Background</p> <p>Road traffic injuries are a major public health problem, especially in low- and middle-income countries. Post-crash management can play a significant role in minimizing crash consequences and saving lives. Iran has one of the highest mortality rates from road traffic injuries in the world. The present study attempts to fill the knowledge gap and explores stakeholders' perceptions of barriers to â and facilitators of â effective post-crash management in Iranian regions.</p> <p>Methods</p> <p>Thirty-six semi-structured interviews were conducted with medical services personnel, police officers, members of Red Crescent, firefighters, public-health professionals, road administrators; some road users and traffic injury victims. A qualitative approach using grounded theory method was employed to analyze the material gathered.</p> <p>Results</p> <p>The core variable was identified as "poor quality of post crash management". Barriers to effective post-crash management were identified as: involvement of laypeople; lack of coordination; inadequate pre-hospital services; shortcomings in infrastructure. Suggestions for laypeople included: 1) a public education campaign in first aid, the role of the emergency services, cooperation of the public at the crash site, and 2) target-group training for professional drivers, police officers and volunteers involved at the crash scene. An integrated trauma system and infrastructure improvement also is crucial to be considered for effective post-crash management.</p> <p>Conclusion</p> <p>To sum up, it seems that the involvement of laypeople could be a key factor in making post-crash management more effective. But system improvements are also crucial, including the integration of the trauma system and its development in terms of human resources (staffing and training) and physical resources as well as the infrastructure development.</p
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