Impact of Clustering Microgrids on Their Stability and Resilience during Blackouts

In this paper, the impact of clustering multiple microgrids during blackouts, on their stability and supply availability, will be investigated. Microgrids have the capability of satisfying their emergency loads during blackouts. However, distributed energy resources (DERs)-dominated microgrids are affected by the uncertainty of their input energy supply, e.g. impact of solar irradiance on photovoltaic (PV) output. Moreover, an individual islanded microgrid is prone to instability issues due to large sudden load/generation changes. In order to increase the supply security, and enhance system stability, we propose to use the existing distribution grid infrastructure, if applicable, during blackouts to form microgrid clusters. The paper discusses the required control hierarchy required to manage the microgrid clusters, and communicate with the Distribution Network Operator (DNO). A case study based on the 13-bus standard distribution feeder, and two microgrid models, is presented. Results show that microgrids clustering helps improve their performance and that the microgrid generator inertia has a direct impact on the stability of the microgrid cluster

Communication Based Control for DC Microgrids

Centralized communication-based control is one of the main methods that can be implemented to achieve autonomous advanced energy management capabilities in DC microgrids. However, its major limitation is the fact that communication bandwidth and computation resources are limited in practical applications. This can be often improved by avoiding redundant communications and complex computations. In this paper, an autonomous communication-based hybrid state/event driven control scheme is proposed. This control scheme is hierarchical and heuristic, such that on the primary control level, it encompasses state-driven local controllers, and on the secondary control level, an event-driven MG centralized controller (MGCC) is used. This heuristic hybrid control system aims at reducing the communication load and complexity, processor computations, and consequently system cost while maintaining reliable autonomous operation during all possible scenarios. A mathematical model for the proposed control scheme using Finite State Machines (FSM) has been developed and used to cover all the possible modes/sub-modes of operation, and assure seamless transitions among them during various events. Results of some case studies involving severe operational scenarios were presented and discussed. Results verify the validity and effectiveness of the proposed communication-based control scheme

Fabrication and characterization of cellulose acetate-based nanofibers and nanofilms for H2S gas sensing application

Electrospun nanofibers and solution-casting nanofilms were produced from an environmentally friendly cellulose acetate (CA) blended with glycerol (as an ionic liquid (IL)), mixed with polypyrrole (PPy, a conducting polymer) and doped with tungsten oxide (WO3) nanoparticles. The sensing membranes fabricated were used to detect H2S gas at room temperature and shown to exhibit high performance. The results revealed that the lowest operating temperature of both nanofiber and nanofilm sensors was 20oC, with a minimum gas detection limit of 1 ppm. Moreover, the sensor exhibits a reasonably fast response, with a minimum average response time of 22.8 and 31.7 s for the proposed nanofiber and nanofilm based sensors, respectively. Furthermore, the results obtained indicated an excellent reproducibility, long-term stability, and low humidity dependence. Such distinctive properties coupled with an easy fabrication technique provide a promising potential to achieve a precise monitoring of harmful H2S gas in both indoor and outdoor atmospheres

Berberine-Induced Amelioration of the Pathological Changes in Nutrient's Homeostasis During Murine Intestinal Eimeria papillata Infection

Abstract.-The current work aimed to study the ameliorative effect of berberine on the induced pathological changes in nutrient's homeostasis in mice infected with Eimeria papillata. Mice were randomly divided into three groups. The first group represents the control non-infected animals. Second and third groups were orally infected with 1.5×10 3 sporulated E. papillata oocysts. The 3 rd group was treated with a daily dose (10 mg/kg) of berberine chloride solution for five successive days. All animals were sacrificed on day 5 p.i.. E. papillata infection induced a state of disturbance in nutrient homeostasis. Blood glucose levels and total proteins were elevated with concurrent decrease in level of carbohydrates and soluble proteins in jejunum of mice. Also, infection induced a hyperlipidemic status as shown from the increase in triglycerides, total lipids, total cholesterol, high density lipoprotein cholesterol (LDL) with the mutual decrease in high density lipoprotein cholesterol (HDL) and phospholipids. Also, E. papillata caused marked disturbance in blood metal ion concentrations. Both ferrous and selenium ion levels were decreased, while sodium and potassium ion concentrations were increased. Berberine treatment of infected mice with E. papillata showed a great enhancement in nutrient homeostatic status and also reduced blood glucose level and restored jejunal carbohydrate content. In addition, berberine exerted hypolipidemic effect on the increased fractions of carbohydrates and lipids. Finally, berberine showed a marked enhancement in the levels of altered blood metal ions by the infection. Palm pollen grains or their extracts could be used within food mixtures or water to correct the induced metabolic disturbance and growth depression associated with the intestinal coccidial infections

SIMVASTATIN TREATMENT AMELIORATES DIABETIC TYPE 2 CONDITIONS THROUGH LOWERING THE CONCENTRATION OF PLASMA ICAM LEVELS

Diabetes type 2 is associated with other diseases including cardiovascular diseases. Obesity is a link between diabetes and cardiovascular diseases and associated with insulin resistance. Statins are used to reduce lipids and to lower the risk of cardiovascular diseases. The objective of the present study was to explore the effect of statin treatment on plasma levels of ICAM among diabetics. The study design was a prospective cohort clinical study. The study included 62 diabetic patients who were recruited from the Diabetes/Endocrine Clinics of the Prince Rashed Hospital. Data were collected from participants through a prepared questionnaire and laboratory findings of lipid profiles, glucose and ICAM levels. Study findings showed no significant variations between study and control groups at baseline level. At the end of the experiment, in study group, there were significant changes in some biochemical parameters such as ICAM level (p=0.005), cholesterol (0.019), and TG (0.025). The mean difference of study and control groups showed that significant variations were observed for the following variables ICAM (p<0.005), cholesterol (p=0.008), TG (p<0.005), and HDDL (p<0.005). Taken together, the present study showed that simvastatin therapy benefits diabetic patients even without hyperlipidemia through decreasing levels of ICAM-1, which have an inflammatory action and increase insulin resistance. It can be concluded that simvastatin is insulin sensitizer and works as anti-inflammatory agent

SIMVASTATIN TREATMENT AMELIORATES DIABETIC TYPE 2 CONDITIONS THROUGH LOWERING THE CONCENTRATION OF PLASMA ICAM LEVELS

Diabetes type 2 is associated with other diseases including cardiovascular diseases. Obesity is a link between diabetes and cardiovascular diseases and associated with insulin resistance. Statins are used to reduce lipids and to lower the risk of cardiovascular diseases. The objective of the present study was to explore the effect of statin treatment on plasma levels of ICAM among diabetics. The study design was a prospective cohort clinical study. The study included 62 diabetic patients who were recruited from the Diabetes/Endocrine Clinics of the Prince Rashed Hospital. Data were collected from participants through a prepared questionnaire and laboratory findings of lipid profiles, glucose and ICAM levels. Study findings showed no significant variations between study and control groups at baseline level. At the end of the experiment, in study group, there were significant changes in some biochemical parameters such as ICAM level (p=0.005), cholesterol (0.019), and TG (0.025). The mean difference of study and control groups showed that significant variations were observed for the following variables ICAM (p<0.005), cholesterol (p=0.008), TG (p<0.005), and HDDL (p<0.005). Taken together, the present study showed that simvastatin therapy benefits diabetic patients even without hyperlipidemia through decreasing levels of ICAM-1, which have an inflammatory action and increase insulin resistance. It can be concluded that simvastatin is insulin sensitizer and works as anti-inflammatory agent

Protective effect of berberine chloride on Plasmodium chabaudi-induced hepatic tissue injury in mice

AbstractThe present study aimed to investigate the protective role of berberine (BER) against Plasmodium chabaudi-induced infection in mice. Animals were divided into three groups. Group I served as a vehicle control. Group II and group III were infected with 1000 P. chabaudi infected erythrocytes. Group III was gavaged with 100μl of 10mg/kg berberine chloride for 10days. All mice were sacrificed at day 10 post-infection. The percentage of parasitemia was significantly reduced more than 30%, after treatment of mice with BER. Infection caused marked hepatic injuries as indicated by histopathological alterations as evidenced by the presence of hepatic lobular inflammatory cellular infiltrations, dilated sinusoids, vacuolated hepatocytes, increased number of Kupffer cells and the malaria pigment, hemozoin. These changes in livers led to the increased histological score. Also, infection induced a significant increase in liver alanine aminotransferase and aspartate aminotransferase and a significant increase in the total leucocytic count. Moreover, mice became anemic as proved by the significant decrease in erythrocyte number and haemoglobin content. BER showed a significant protective potential by improving the above mentioned parameters. Based on these results, it is concluded that berberine could offer protection against hepatic tissue damage

COMPARATIVE ANALYSIS OF BIOLOGICAL ACTIVITY OF SILYBUM MARIANUM L. FOOD SUPPLEMENTS AVAILABLE ON MARKET: INVITRO STUDY

Objective: Silybum marianum L. Food Supplements that contain silymarin is widely used as a therapeutic agent in liver diseases. Many brands are available on the market in USA, Egypt, Europe and other countries. The objective of this study was to compare the biological activity in different preparations of silymarin available on the market in USA and Egypt using paracetamol-induced oxidative stress injury on primary cultured rat hepatocytes. Methods: Forty four silymarin samples available on the market were collected from USA (24) and Egypt (20) and tested for hepat protective antioxidant effects on primary cultured rat hepatocytes. Cytotoxicity was measured by MTT [3-(4, 5-dimethyl-thiazol-2)-2,5-diphenyl tetrazolium bromide] assay and lactate dehydrogenase (LD) leakage into culture medium. Antioxidant effects were determined by glutathione reductase (GR), and Nitric oxide (NO) assays in silymarin, pretreated rat hepatocytes for 2 h followed by incubation with 25 mM paracetamol over a period of 1 h. Therapeutic index was calculated for each tested sample for comparative analysis. Results: Silymarin preparations significantly decreased toxicity induced by paracetamol in rat hepatocytes, decreased lactate dehydrogenase leakage and prevented GSH depletion (P<0.01) and returned NO to basal levels in rat hepatocytes. The therapeutic index was 80, 40 and 20 for samples No. 20, 19 and 5 respectively. Conclusions: The 44 different silymarin preparations tested in this study exhibited variation in antioxidant capacity and in reducing nitric oxide produced as a result of paracetamol injury. This variation in biological activity did not always correspond to the amount of silymarin recorded on samples

Dose Optimization of Colistin: A Systematic Review

Colistin is considered a last treatment option for multi-drug and extensively resistant Gram-negative infections. We aimed to assess the available data on the dosing strategy of colistin. A systematic review was performed to identify all published studies on the dose optimization of colistin. Grey literature and electronic databases were searched. Data were collected in a specified form and the quality of the included articles was then assessed using the Newcastle-Ottawa scale for cohort studies, the Cochrane bias tool for randomized clinical trials (RCT), and the Joanna Briggs Institute (JBI) critical checklist for case reports. A total of 19 studies were included, of which 16 were cohort studies, one was a RCT, and two were case reports. A total of 18 studies proposed a dosing regimen for adults, while only one study proposed a dosing schedule for pediatric populations. As per the available evidence, a loading dose of 9 million international units (MIU) of colistin followed by a maintenance dose of 4.5 MIU every 12 h was considered the most appropriate dosing strategy to optimize the safety and efficacy of treatment and improve clinical outcomes. This review supports the administration of a loading dose followed by a maintenance dose of colistin in severe and life-threatening multi-drug Gram-negative bacterial infections

Dose optimization of β-lactams antibiotics in pediatrics and adults:A systematic review

Background: β-lactams remain the cornerstone of the empirical therapy to treat various bacterial infections. This systematic review aimed to analyze the data describing the dosing regimen of β-lactams. Methods: Systematic scientific and grey literature was performed in accordance with Preferred Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The studies were retrieved and screened on the basis of pre-defined exclusion and inclusion criteria. The cohort studies, randomized controlled trials (RCT) and case reports that reported the dosing schedule of β-lactams are included in this study. Results: A total of 52 studies met the inclusion criteria, of which 40 were cohort studies, 2 were case reports and 10 were RCTs. The majority of the studies (34/52) studied the pharmacokinetic (PK) parameters of a drug. A total of 20 studies proposed dosing schedule in pediatrics while 32 studies proposed dosing regimen among adults. Piperacillin (12/52) and Meropenem (11/52) were the most commonly used β-lactams used in hospitalized patients. As per available evidence, continuous infusion is considered as the most appropriate mode of administration to optimize the safety and efficacy of the treatment and improve the clinical outcomes. Conclusion: Appropriate antibiotic therapy is challenging due to pathophysiological changes among different age groups. The optimization of pharmacokinetic/pharmacodynamic parameters is useful to support alternative dosing regimens such as an increase in dosing interval, continuous infusion, and increased bolus doses