Performance Simulation of Planar Solid Oxide Fuel Cells

The performance of solid oxide fuel cells (SOFCs) at the cell and system levels is studied using computer simulation. At the cell level, a new model combining the cell micro and macro models is developed. Using this model, the microstructural variables of porous composite electrodes can be linked to the cell performance. In this approach, the electrochemical performance of porous composite electrodes is predicted using a micro-model. In the micro-model, the random-packing sphere method is used to estimate the microstructural properties of porous composite electrodes from the independent microstructural variables. These variables are the electrode porosity, thickness, particle size ratio, and size and volume fraction of electron-conducting particles. Then, the complex interdependency among the multi-component mass transport, electron and ion transports, and the electrochemical and chemical reactions in the microstructure of electrodes is taken into account to predict the electrochemical performance of electrodes. The temperature distribution in the solid structure of the cell and the temperature and species partial pressure distributions in the bulk fuel and air streams are predicted using the cell macro-model. In the macro-model, the energy transport is considered for the cell solid structure and the mass and energy transports are considered for the fuel and air streams. To demonstrate the application of the cell level model developed, entitled the combined micro- and micro-model, several anode-supported co-flow planar cells with a range of microstructures of porous composite electrodes are simulated. The mean total polarization resistance, the mean total power density, and the temperature distribution in the cells are predicted. The results of this study reveal that there is an optimum value for most of the microstructural variables of the electrodes at which the mean total polarization resistance of the cell is minimized. There is also an optimum value for most of the microstructural variables of the electrodes at which the mean total power density of the cell is maximized. The microstructure of porous composite electrodes also plays a significant role in the mean temperature, the temperature difference between the hottest and coldest spots, and the maximum temperature gradient in the solid structure of the cell. Overall, using the combined micro- and micro-model, an appropriate microstructure for porous composite electrodes to enhance the cell performance can be designed. At the system level, the full load operation of two SOFC systems is studied. To model these systems, the basic cell model is used for SOFCs at the cell level, the repeated-cell stack model is used for SOFCs at the stack level, and the thermodynamic model is used for the balance of plant components of the system. In addition to these models, a carbon deposition model based on the thermodynamic equilibrium assumption is employed. For the system level model, the first SOFC system considered is a combined heat and power (CHP) system that operates with biogas fuel. The performance of this system at three different configurations is evaluated. These configurations are different in the fuel processing method to prevent carbon deposition on the anode catalyst. The fuel processing methods considered in these configurations are the anode gas recirculation (AGR), steam reforming (SR), and partial oxidation reformer (POX) methods. The application of this system is studied for operation in a wastewater treatment plant (WWTP) and in single-family detached dwellings. The evaluation of this system for operation in a WWTP indicates that if the entire biogas produced in the WWTP is used in the system with AGR or SR fuel processors, the electric power and heat required to operate the plant can be completely supplied and the extra electric power generated can be sold to the electrical grid. The evaluation of this system for operation in single-family detached dwellings indicates that, depending on the size, location, and building type and design, this system with all configurations studied is suitable to provide the domestic hot water and electric power demands. The second SOFC system is a novel portable electric power generation system that operates with liquid ammonia fuel. Size, simplicity, and high electrical efficiency are the main advantages of this environmentally friendly system. Using a sensitivity analysis, the effects of the cell voltage at several fuel utilization ratios on the number of cells required for the SOFC stack, system efficiency and voltage, and excess air required for thermal management of the SOFC stack are studied

Enhancing the Dyeability of Polypropylene Fibers by Melt Blending with Polyethylene Terephthalate

Attempts were made to modify polypropylene fibers by melt blending with polyethylene terephthalate in order to enhance the dyeability of the resultant fiber. Five blends of polypropylene/polyethylene terephthalate/compatibilizer were prepared and subsequently spun into fibers. Three disperse dyes were used to dye such modified fibers at boiling and 130°C. The dyeing performance of the blend fibers, as well as the morphological, chemical, thermal, and mechanical properties, of the corresponding blends was characterized by means of spectrophotometry, polarized optical microscopy, scanning electron microscopy (SEM), FT-IR spectroscopy, differential scanning calorimetry (DSC), and tensile testing

بررسی تغییرات فیزیولوژیکی فشار خون، ضربان قلب و استرس شغلی کارگران کارگاه چوب بری در مواجهه با صدا

Background and Aims: The aim of this study was to investigate the level of noise exposure and its relationship with job stress, changes in blood pressure and heart rate among woodworking workshop workers. Materials and Methods: In this cross-sectional-analytical-descriptive study, 140 employees of a lumber workshop in Mazandaran province were selected and divided into case and control groups. Demographic information of employees was collected by questionnaire. Systolic and diastolic blood pressure were measured using mercury sphygmomanometer. Heart rate of the case and control groups was measured by Beurer pulse meter. The results were analyzed using SPSS software. Results: The results of noise measurements showed that the mean noise exposure in workers from 8-hour shifts was 92.11 dB and among non-exposed group was 74.48 dB. The mean systolic and diastolic blood pressure in the control and exposure groups were 124, 126, 80 and 82, respectively. Also, the mean heart rate of the studied groups was 74.9 and 75.83 beats per minute, respectively. There was no significant difference in systolic and diastolic blood pressure and heart rate between the two groups, (p> 0.05). Conclusion: Based on the findings, the rate of systolic and diastolic blood pressure, as well as the heart rate and stress levels were higher in the exposed group as compared with the control group; however, the difference between systolic, diastolic blood pressure and heart rate between the two groups was not statistically significant. There was a significant difference in stress. It was found to be consistent with the results of some previous studies.زمینه و اهداف: هدف از انجام مطالعه حاضر بررسی میزان مواجهه با صدا و ارتباط آن با استرس شغلی، تغییرات فشارخون و ضربان قلب در کارگران کارگاه چوب‌بری بود. مواد و روش‌ها: در این مطالعه مقطعی- تحلیلی- توصیفی تعداد140 نفر از شاغلین یک کارگاه چوب بری در استان مازندران انتخاب و در دو گروه مورد و کنترل تقسیم شدند. اطلاعات جمعیت‌شناختی شاغلین با پرسشنامه گردآوری شد. میزان فشارخون سیستولیک و دیاستولیک با استفاده از فشارسنج جیوه‌ای و ضربان قلب گروه مورد و شاهد به‌ وسیله دستگاه نبض سنج Beurer مورد سنجش قرار گرفت. نتایج بدست آمده با استفاده از نرم افزار  SPSS تجزیه و تحلیل شد. در تمام مراحل، ملاحظات اخلاقی مد نظر قرار گرفت. یافته‌ها: نتایج اندازه‌گیری صدا نشان داد، میانگین مواجهه با صوت در شاغلین مواجهه یافته در شیفت 8 ساعته 92/11 دسی‌بل و گروه بدون مواجهه 74/48 دسی‌بل است. میانگین فشار خون سیستولیک، دیاستولیک به ترتیب در دو گروه کنترل و مواجهه 124،126، 80 و 82 بود.  همچنین میانگین ضربان قلب دو گروه  به ترتیب 74/9 و 75/83 ضربه در دقیقه بود. همچنین تفاوت معنی‌داری در فشار خون سیستولیک و دیاستولیک و ضربان قلب بین دو گروه وجود نداشت (P>0/05). نتیجه‌گیری: نتایج مطالعه نشان داد، میزان فشار خون سیستولیک، دیاستولیک، ضربان قلب و استرس در گروه مواجهه بیشتر از گروه کنترل بود و اختلاف فشار خون سیستولیک، دیاستولیک و ضربان قلب بین دو گروه  از نظر آماری معنی‌دار نبوده و فقط در میزان استرس اختلاف معنی‌داری مشاهده شد

Impact of psychological problems in chemical warfare survivors with severe ophthalmologic complication, a cross sectional study

<p>Abstract</p> <p>Background</p> <p>Sulfur mustard (SM) has been used as a chemical warfare agent since the early twentieth century. Despite the large number of studies that have investigated SM induced ocular injuries, few of those studies have also focused on the psychological health status of victims. This study has evaluated the most prominent influences on the psychological health status of patients with severe SM induced ocular injuries.</p> <p>Methods</p> <p>This descriptive study was conducted on 149 Iranian war veterans with severe SM induced eye injuries. The psychological health status of all patients was assessed using the Iranian standardized Symptom Check List 90-Revised (SCL90-R) questionnaire. The results of patients' Global Severity Index (GSI) were compared with the optimal cut-off point of 0.4 that has previously been calculated for GSI in Iranian community. The Mann-Whitney U test, T tests and effect sizes (using Cohen's d) were employed as statistical methods. Data were analyzed using SPSS software.</p> <p>Results</p> <p>The mean age of patients was 44.86 (SD = 8.7) and mean duration of disease was 21.58 (SD = 1.20) years. Rate of exposure was once in 99 (66.4%) cases. The mean GSI (1.46) of the study group was higher compared to standardized cut off point (0.4) of the Iranian community. The results of this study showed that the mean of total GSI score was higher in participants with lower educational levels (effect size = 0.507), unemployment (effect size = 0.464) and having more than 3 children (effect size = 0.62). Among the participants, 87 (58.4%) cases had a positive psychological history for hospitalization or receiving outpatient cares previously and 62 (41.6%) cases had a negative psychological history. In addition, the mean of GSI in participants with negative psychological history was lower than those with positive psychological history (Mean Change Difference = -0.621 with SD = 0.120). There was a significant difference between positive and negative psychological history with respect to GSI (P < 0.001).</p> <p>Conclusion</p> <p>The study showed that severe ophthalmologic complications in chemical survivors are accompanied with destructive effects on psychological health status. Appropriate management may improve psychological health status in these patients.</p

Impact of psychological problems in chemical warfare survivors with severe ophthalmologic complication, a cross sectional study

Abstract Background: Sulfur mustard (SM) has been used as a chemical warfare agent since the early twentieth century. Despite the large number of studies that have investigated SM induced ocular injuries, few of those studies have also focused on the psychological health status of victims. This study has evaluated the most prominent influences on the psychological health status of patients with severe SM induced ocular injuries. Methods: This descriptive study was conducted on 149 Iranian war veterans with severe SM induced eye injuries. The psychological health status of all patients was assessed using the Iranian standardized Symptom Check List 90-Revised (SCL90-R) questionnaire. The results of patients&apos; Global Severity Index (GSI) were compared with the optimal cut-off point of 0.4 that has previously been calculated for GSI in Iranian community. The Mann-Whitney U test, T tests and effect sizes (using Cohen&apos;s d) were employed as statistical methods. Data were analyzed using SPSS software. Results: The mean age of patients was 44.86 (SD = 8.7) and mean duration of disease was 21.58 (SD = 1.20) years. Rate of exposure was once in 99 (66.4%) cases. The mean GSI (1.46) of the study group was higher compared to standardized cut off point (0.4) of the Iranian community. The results of this study showed that the mean of total GSI score was higher in participants with lower educational levels (effect size = 0.507), unemployment (effect size = 0.464) and having more than 3 children (effect size = 0.62). Among the participants, 87 (58.4%) cases had a positive psychological history for hospitalization or receiving outpatient cares previously and 62 (41.6%) cases had a negative psychological history. In addition, the mean of GSI in participants with negative psychological history was lower than those with positive psychological history (Mean Change Difference = -0.621 with SD = 0.120). There was a significant difference between positive and negative psychological history with respect to GSI (P &lt; 0.001)

Global, regional, and national cancer incidence, mortality, years of life lost, years lived with disability, and disability-Adjusted life-years for 29 cancer groups, 1990 to 2017 : A systematic analysis for the global burden of disease study

Importance: Cancer and other noncommunicable diseases (NCDs) are now widely recognized as a threat to global development. The latest United Nations high-level meeting on NCDs reaffirmed this observation and also highlighted the slow progress in meeting the 2011 Political Declaration on the Prevention and Control of Noncommunicable Diseases and the third Sustainable Development Goal. Lack of situational analyses, priority setting, and budgeting have been identified as major obstacles in achieving these goals. All of these have in common that they require information on the local cancer epidemiology. The Global Burden of Disease (GBD) study is uniquely poised to provide these crucial data. Objective: To describe cancer burden for 29 cancer groups in 195 countries from 1990 through 2017 to provide data needed for cancer control planning. Evidence Review: We used the GBD study estimation methods to describe cancer incidence, mortality, years lived with disability, years of life lost, and disability-Adjusted life-years (DALYs). Results are presented at the national level as well as by Socio-demographic Index (SDI), a composite indicator of income, educational attainment, and total fertility rate. We also analyzed the influence of the epidemiological vs the demographic transition on cancer incidence. Findings: In 2017, there were 24.5 million incident cancer cases worldwide (16.8 million without nonmelanoma skin cancer [NMSC]) and 9.6 million cancer deaths. The majority of cancer DALYs came from years of life lost (97%), and only 3% came from years lived with disability. The odds of developing cancer were the lowest in the low SDI quintile (1 in 7) and the highest in the high SDI quintile (1 in 2) for both sexes. In 2017, the most common incident cancers in men were NMSC (4.3 million incident cases); tracheal, bronchus, and lung (TBL) cancer (1.5 million incident cases); and prostate cancer (1.3 million incident cases). The most common causes of cancer deaths and DALYs for men were TBL cancer (1.3 million deaths and 28.4 million DALYs), liver cancer (572000 deaths and 15.2 million DALYs), and stomach cancer (542000 deaths and 12.2 million DALYs). For women in 2017, the most common incident cancers were NMSC (3.3 million incident cases), breast cancer (1.9 million incident cases), and colorectal cancer (819000 incident cases). The leading causes of cancer deaths and DALYs for women were breast cancer (601000 deaths and 17.4 million DALYs), TBL cancer (596000 deaths and 12.6 million DALYs), and colorectal cancer (414000 deaths and 8.3 million DALYs). Conclusions and Relevance: The national epidemiological profiles of cancer burden in the GBD study show large heterogeneities, which are a reflection of different exposures to risk factors, economic settings, lifestyles, and access to care and screening. The GBD study can be used by policy makers and other stakeholders to develop and improve national and local cancer control in order to achieve the global targets and improve equity in cancer care. © 2019 American Medical Association. All rights reserved.Peer reviewe

Global injury morbidity and mortality from 1990 to 2017 : results from the Global Burden of Disease Study 2017

Correction:Background Past research in population health trends has shown that injuries form a substantial burden of population health loss. Regular updates to injury burden assessments are critical. We report Global Burden of Disease (GBD) 2017 Study estimates on morbidity and mortality for all injuries. Methods We reviewed results for injuries from the GBD 2017 study. GBD 2017 measured injury-specific mortality and years of life lost (YLLs) using the Cause of Death Ensemble model. To measure non-fatal injuries, GBD 2017 modelled injury-specific incidence and converted this to prevalence and years lived with disability (YLDs). YLLs and YLDs were summed to calculate disability-adjusted life years (DALYs). Findings In 1990, there were 4 260 493 (4 085 700 to 4 396 138) injury deaths, which increased to 4 484 722 (4 332 010 to 4 585 554) deaths in 2017, while age-standardised mortality decreased from 1079 (1073 to 1086) to 738 (730 to 745) per 100 000. In 1990, there were 354 064 302 (95% uncertainty interval: 338 174 876 to 371 610 802) new cases of injury globally, which increased to 520 710 288 (493 430 247 to 547 988 635) new cases in 2017. During this time, age-standardised incidence decreased non-significantly from 6824 (6534 to 7147) to 6763 (6412 to 7118) per 100 000. Between 1990 and 2017, age-standardised DALYs decreased from 4947 (4655 to 5233) per 100 000 to 3267 (3058 to 3505). Interpretation Injuries are an important cause of health loss globally, though mortality has declined between 1990 and 2017. Future research in injury burden should focus on prevention in high-burden populations, improving data collection and ensuring access to medical care.Peer reviewe