This study explains the modeling of synthesized membranes using the Donnan Steric Pore model (DSPM) based on the Extended Nernst Planck Equation (ENP). Conventionally, structural parameters required ...to predict the performance of the membranes were determined through tedious experimentation, which in this study are found using a new MATLAB technique. A MATLAB program is used to determine the unknown structural parameters such as effective charge density (Xd), effective pore radius (rp), and effective membrane thickness to porosity ratio (Δx/Ak) by using the single solute rejection and permeation data. It was found that the model predicted the rejection of studied membranes accurately, with the E5C1 membrane exceeding the others (E5, E5C5) for rejection of single and divalent salt's aqueous solutions. The rejection of 100 ppm aqueous solution of NaCl for E5C1 was around 60%, whereas, for an aqueous solution of 100 ppm, CaCl2 rejection reached up to 80% at 10 bar feed pressure. The trend of salt rejection for all three membranes was found to be in the following order: E5C1 > E5C5 > E5, confirming that their structural parameters-controlled ion transport in these membranes. The structural parameters, such as effective pore radius, effective membrane thickness to porosity ratio, and effective charge density for the best performing membrane, i.e., E5C1, were determined to be 0.5 nm, 16 μm, and −6.04 mol/m3,respectively. Finally, it can be asserted that this method can be used to predict the real performance of membranes by significantly reducing the number of experiments previously required for the predictive modeling of nanofiltration-type membranes.
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•MATLAB based approach to predict membrane performance.•Rejection of mono and divalent salts for PES/CMS membranes.•DSPM with ENP equation was used to predict the performance of PES/CMS membranes.
Nanoparticle dispersions at a minute concentration in salt mixtures have recently been reported to significantly increase their specific heat capacity. However, there is a discrepancy between ...experimental results reported for the same kind of molten salt-nanoparticle mixtures by different research groups. From our literature survey, we learned that there is no standardized synthesis protocol for preparing molten salt nanofluids. In general, two-step method has been the most widely used in the literature. Nanoparticles and salts are dispersed in an aqueous solution. The mixture is then ultrasonicated to disperse the nanoparticles homogeneously. The mixture is then dried at elevated temperatures to obtain uniformly mixed salt-nanoparticle mixture, which results in a molten salt nanofluid when the mixture is heated above the melting point of the salt mixture. In this method, the duration of the ultrasonication can play an important role in the dispersion of nanoparticles. However, there is no consensus on how much time is required to disperse nanoparticles homogeneously. Literature survey shows that the duration of ultrasonication used to prepare molten salt nanofluids varies from 0.5 h to 5 h. In this study, we assume that the discrepancy reported in the literature could be due to different ultrasonication times used in different studies. We chose the most widely studied molten salt nanofluids, synthesized in different ultrasonication times, compared their specific heat capacity enhancements, and proposed the optimum ultrasonication time to apply for future molten salt nanofluid preparation. Thermogravimetric analysis was performed to study the thermal stability of the pure salts and nanofluids from 100 °C to 600 °C. Nanofluids prepared using 3 h of ultrasonication time showed the highest enhancement of 1.70 kJ/kg°C, which was approximately 15.6 % higher than the pure base salts. The result of the study can be impactful in solar energy industry sector and can be used as a guideline to prepare molten salt nanofluids for their solar thermal energy storage media.
•Molten salt-based nanofluids were synthesized by dispersing SiO2 nanoparticles into solar salt.•The results show the sonication time during the synthesis affects the effective specific heat capacity of the nanofluids.•We varied the sonication time from 1.5 hours to 5.0 hours and determined the optimum sonication time.•We explained the underlying mechanism behind the enhanced specific heat capacity.
Leading wind turbine manufacturers are running life extension programs for their installed wind farms which include fixed speed induction generator-based wind turbines (FSIG-WT). To accommodate the ...requirement of recent grid codes in these upgrades, this paper presents a new topological configuration to enhance the fault ride through (FRT) operation of FSIG-WT. The topology comprises ten semiconductor switches in total and performs shunt and series compensation concurrently in response to the dynamic grid conditions. A coordinated control strategy is developed for the proposed topology to ensure smooth steady state operation, enhanced transient response, and most importantly, FRT capability in adherence to the recent grid code requirements. In addition, the control strategy maintains the linear modulation range and uniform switching frequency across all the switches participating in series and shunt compensation. The validity of the proposed topology and the coordinated control strategy is verified through extensive simulation study under different operating conditions.
The study investigates the factors that control the isotopic composition of tropical precipitation in Bangladesh. Daily and monthly rainfall samples were collected from three stations from 2013 to ...2015: (1) northern and moderately high altitude: Sylhet, (2) middle part of the country (close to Tropic of Cancer): Savar, and (3) southern coastal region: Barisal. To escape from the post-evaporation effect, proper care was adopted. This is supported by the fact that the local meteoric water lines (LMWLs) derived for the daily precipitations of all stations mostly follow the global meteoric water line (GMWL). The results exhibit a clear seasonal and spatial variation in both δ
18
O and δ
2
H of precipitation.
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O is more depleted in samples collected during rainy (monsoon) seasons, while
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O enrichment is associated to winter and summer (pre-monsoon) seasons. During rainy season, intra-seasonal variability of δ
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O rainfall is clearly seen and remarkable depletion of
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O is observed during the period of intense convective activity over the Bay of Bengal. This feature indicates that isotope variability in Bangladesh is controlled by large-scale convective activity rather than local rainfall amount.
Drought is one of the most destructive abiotic stresses that impact the growth, physiology, yield, and nutritional quality of seeds of crop plants. In modern agriculture, the use of nanoparticles can ...be beneficial due to their large surface area and higher potentiality to enter into the plant leaf during foliar application. This study aims to evaluate the effects of foliar spray containing varying doses (0, 100, and 200 ppm) of the nano-iron (Fe
3
O
4
) on the growth, physiology, yield, and seed nutritional quality of soybean under drought (40% of field capacity, FC) and well-watered (80% of FC) conditions. Leaf water status, chlorophyll content of leaves, the height of the plant, fresh leaf weight, fresh stem weight, fresh petiole weight, total dry weight, seed yield, and protein and oil content in soybean seeds were found to be suppressed by the applied drought stress. Under both drought (40% of FC) and controlled well-watered (80% of FC) conditions, the foliar application of nano-iron substantially improved the growth, physiology, yield, and quality of soybean seeds. The nanoparticles at 200 ppm increased soybean seed yield by 40.12 and 32.60% in drought and well-watered conditions, respectively, compared to the untreated plants. Furthermore, nano-iron increased the oil content of soybean seeds by 10.14 and 7.87% under drought and well-watered conditions, respectively, compared to the untreated control. Our results indicate that the application of nano-iron improved drought tolerance, yield, and seed quality of soybean, so exogenous foliar sprays of 200 ppm Fe
3
O
4
were more effective than the other treatments in enhancing drought tolerance and can be utilized to reduce losses caused by drought stress in soybean-growing areas.
The COVID-19 pandemic has stretched healthcare resources thin and led to significant morbidity and mortality. There have been no studies utilizing national data to investigate the role of cardiac ...risk factors on outcomes of COVID hospitalizations. The aim of this study was to examine the effect of cardiac multimorbidity on healthcare utilization and outcomes among COVID hospitalizations during the first year of the pandemic.
Using the national inpatient sample (NIS), we identified all adult hospital admissions with a primary diagnosis of COVID in 2020, using International Classification of Diseases, Tenth Revision, Clinical Modification codes (ICD010-CM). Coronary artery disease, diabetes mellitus, heart failure, peripheral vascular disease, previous stroke, and atrial fibrillation were then identified as cardiac comorbidities using ICD-10-CM codes. Multivariable logistic regression was used to evaluate the effect of cardiac multimorbidity on mortality and mechanical ventilation.
We identified 1,005,040 primary COVID admissions in 2020. Of these admissions, 216,545 (20.6%) had CAD, 413,195 (39.4%) had DM, 176,780 (16.8%) had HF, 159,700 (15.2%) had AF, 30735 (2.9%) had PVD, and 25,155 (2.4%) had a previous stroke. When stratified by number of comorbidities, 428390 (40.8%) had 0 comorbidities, 354960 (33.8%) had 1, 161225 (15.4%) had 2, and 105465 (10.0%) had 3+ comorbidities. COVID hospitalizations with higher cardiac multimorbidity had higher mortality rates (p<0.001) higher MV rates (p<0.001). In our multivariable regression, these associations remained with increasing odds for mortality with each stepwise increase in cardiac multimorbidity (1: OR 1.48 (1.45-1.50); 2: OR 2.13 (2.09-2.17); 3+: OR 2.43 (2.38-2.48), p<0.001, all).
Our study is the first national examination of the impact of cardiac comorbidities on COVID outcomes. A higher number of cardiac comorbidities was associated with significantly higher rates of MV and in-hospital mortality, independent of age. Future, more granular, and longitudinal studies are needed to further examine these associations.
Heat waves significantly impact people's lives and livelihoods and are becoming very alarming and recognized as hot topics worldwide, including in Bangladesh. However, much less is understood ...regarding recent hotspots, the frequency of heat waves over time, and their underlying causes in Bangladesh. The objective of the study is to explore the current scenario and frequency of heat waves and their possible causes across Bangladesh. The Mann-Kendall and Sen's slope techniques were used to determine seasonal and annual temperature trend patterns of heat wave frequencies. Daily maximum temperature datasets collected from the Bangladesh Meteorological Department (BMD) during 1991-2021 are applied. The frequency of days with Tmax≥ 36°C as the threshold was used to compute different types of heat waves based on the BMD's operational definition. The results show that the mild heat wave (MHW) days followed the subsequent hotspot order: Rajshahi (103) > Chuadanga (79), Ishurdi (60), and Jessore (58), respectively. The frequency of days with Tmax≥36°C was persistence for many days in 2014, especially in the western part of Bangladesh compared to other parts. Similarly, the heat waves condition shown its deadliest event by increasing more days in 2021. The highest increasing trend was identified at the Patuakhali site, with a rate of 0.516 days/year, while the highest decreasing trend was noticed at the Chuadanga site, with a rate of -0.588 days/year. The frequency of days (Tmax≥36°C) is an increasing trend in the south-western part of Bangladesh. The synoptic condition in and around Bangladesh demonstrates that the entrance of heat waves in Bangladesh is due to the advection of higher temperatures from the south/southwest of the Bay of Bengal. The outcomes will guide the national appraisal of heatwave effects, shedding light on the primary causes of definite heatwave phenomena, which are crucial for developing practical adaptation tools.
Statins have strong recommendations for secondary prevention of future cardiovascular events in patients with ischemic heart disease (IHD).1 However, statins remain vastly underused in patients with ...cardiovascular disease and those at high risk of cardiovascular disease.2 The identified factors contributing to health care disparities in vulnerable population include having a low income, older age, being residents of rural area, and residing in southeastern United States.3 Multiple analyses from various databases have reported that disparities in optimal use of statins are more prevalent among racial/ethnic minorities.4,5 Despite adequate availability, statin use is affected by insurance coverage and out-of-pocket cost especially in low-income households.6,7 Consequently, we sought to evaluate the utilization trends of statins among outpatient visits of adults with IHD within the Medicaid population in the United States from 2006 to 2015 using the National Ambulatory Medical Care Survey (NAMCS) database. The generalizability of our results is limited due to being primarily based on patients with Medicaid. ...there are no data available regarding contraindication or adverse effects of statins, which may have affected statin prescription. ...to the best of our knowledge, our study is the first to report statin use in patients with Medicaid with IHD at a national level.
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