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Search Results: 1 - 10 of 416463 matches for " Ghada M. Al-Naemi "
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Global Convergence Property with Inexact Line Search for a New Hybrid Conjugate Gradient Method  [PDF]
Fanar N. Al-Namat, Ghada M. Al-Naemi
Open Access Library Journal (OALib Journal) , 2020, DOI: 10.4236/oalib.1106048
In this study, we derive a new scale parameter φ for the CG method, for solving large scale unconstrained optimization algorithms. The new scale parameter φ satisfies the sufficient descent condition, global convergence analysis proved under Strong Wolfe line search conditions. Our numerical results show that the proposed method is effective and robust against some known algorithms.
Assessment of Radiation Dose for Non-Radiation Workers in the Medical Field Practices  [PDF]
Huda M. Al-Naemi
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2015, DOI: 10.4236/ijmpcero.2015.42012
Radiation protection programs aims to reduce the radiation dose to the lowest possible level under the Dose Limit (DL) limit by the national or international laws, while the dose monitoring programs working as scale used to evaluating the efficiency of these programs and tools. In this study, the average of the annual Eff dose for the intensive care units at Hamad General Hospital (HGH) is less than the 50% of DL. It was aiming also to evaluate the efficiency of the radiation safety requirements (especially the shielding Adequacy) for the non radiation workers at oncology centers, hence several monitors were installed in chosen locations outside the radiation treatment machine from 2007 to 2011.
Analysis and Modeling of Buck Converter in Discontinuous-Output-Inductor-Current Mode Operation  [PDF]
Jianbo Yang, Weiping Zhang, Faris Al-Naemi, Xiaoping Chen
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B163

The Buck converter with LC input filter operating in discontinuous output current mode has a high power factor with a constant duty cycle. A Buck converter in this operation mode can reduce the reverse recovery loss of the freewheeling diode thus increase the efficiency. The operation, power factor analysis and modeling of the converter are studied in this paper. Experimental results are presented to verify the theoretical predictions.

Comparisons between CRM and CCM PFC  [PDF]
Weiping Zhang, Wei Zhang, Jianbo Yang, Faris Al-Naemi
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B165

The paper presents detailed comparisons between CRM (critical conduction mode) and CCM (continuous conduction mode) control schemes used for Boost PFC converter. The two schemes are analyzed and compared under the chips of L6561 and UC 3854 which are commonly used for CRM and CCM respectively. Both schemes are based on multiplier; however, the CCM is more complex and needs more periphery components which increase the cost. The Boost PFC under CRM is easier to be implemented. Nevertheless, the variable switch frequency makes the system (including the power-stage inductor and capacitor) hard to design. It seems that the CRM PFC is more attractive in low power applications which only need to meet IEC61000-3-2 D standard. Some experiment results are also presented for the comparison.

A High Power Factor Rectifier Based on Buck Converter Operating in Discontinuous Inductor Current Mode  [PDF]
Jianbo Yang, Weiping Zhang, Faris Al-Naemi, Xiaoping Chen
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B162

By adding a suitable LC filter to the input of a Buck converter, a high-power-factor buck converter is proposed. The converter can operate in the discontinuous-output-current mode operation. A Buck converter in this operation mode features simple control as the constant duty cycle PWM used. The operation condition of the converter is studied. The validity of analysis is verified by Simulation and Experimental results.

A Single Phase Current Source PFC Converter Based on UC3854  [PDF]
Jianbo Yang, Weiping Zhang, Faris Al-Naemi, Xiaoping Chen
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B164

A novel high-power-factor Buck type converter with average current control based on UC 3854 is proposed. The input current is directly controlled by average current control scheme to deliver sinusoidal input current and to gain a high power factor. The practical results, which illustrate the proposed control philosophy, were obtained from a 120 W AC/DC Buck type converter. The power factor can reach 0.97.

Gut Microbiota Dysbiosis in Cafeteria Diet Fed Sprague Dawley Rats  [PDF]
Kavitha Varadharajan, Muralitharan Shanmugakonar, Sandra Concepcion Das, Hamda A. Al-Naemi
Advances in Microbiology (AiM) , 2018, DOI: 10.4236/aim.2018.812066
Abstract: Diet plays a major role in the body physiology and metabolism. The quantity, nature and stability of the macronutrients present in the diet have a major impact on the composition of gut microbiota. Gut microbiota plays a major role in the body metabolism and leads to obese or lean phenotype. Bacteriodetes, Firmicutes, Proteobacteria and Actinobacteria are the major microbes that inhabit in the region of the gut. We made an attempt to study the effects of Cafeteria (CAF) diets and normal chow diets on diet consumption, weight gain, metabolism and composition of gut microbiota in fecal and cecum samples from three weeks old Sprague Dawley (SD) rats (n = 18/group) using 16S rDNA high throughput sequencing. Results revealed that distinctive diet based phenotypical changes were observed in some of the Cafeteria diet fed rats. Interestingly, some weight gain resistant (WGR) animals in Cafeteria diet fed groups show similar trend like that of control normal chow fed rats. Fecal microbiome analysis indicates that the ratio of Bacteriodetes is higher than the Firmicutes in cecum samples of Cafeteria diet fed rats whereas no significant difference is found in fecal samples of Cafeteria diet fed rats and as well as in control rats. Further analysis of other taxa at the level of family and genus of microbial abundance are also discussed. Our study suggests that contribution of gut microbiota towards obesity is not at the phylum level, and microbiome composition even at the level of species or strain may exert impact on the metabolism of the Cafeteria diet.
Cadmium Toxicity: Oxidative Stress, Inflammation and Tissue Injury  [PDF]
Sandra Concepcion Das, Hamda A. Al-Naemi
Occupational Diseases and Environmental Medicine (ODEM) , 2019, DOI: 10.4236/odem.2019.74012
Abstract: Cadmium is a known environmental pollutant targeting various organs. Often implicated in cadmium toxicology is the formation of reactive oxygen species, overwhelming the free radical scavenging mechanisms and inducing oxidative stress. Acute cadmium intoxication has been shown to reduce antioxidant enzyme activity and induce oxidative stress. However, chronic intoxication has obscure outcomes in oxidative stress while the cell makes adjustments to overcome the toxicant load. Also linked with the occurrence of oxidative stress is inflammation. Stimulation of acute or chronic inflammation is mediated by different cascades. However, key events include activation of transcription factor, NF-κB and release of pro-inflammatory cytokines. Both oxidative stress and inflammation are implicated simultaneously in pathogenesis and induction of multi-organ tissue damage under cadmium exposure. This article reviews the impact of acute and chronic cadmium intoxication on inducing oxidative stress, inflammation and thereby inflicting tissue damage.
Impact of oxidative stress on pregnancy outcome in albino rats
R.S. Al-Naemi,Q.H. Abdullah,S.A. Ibrahim
Iraqi Journal of Veterinary Sciences , 2012,
Abstract: Accumulative reports documented that oxidative stress is implicated in many human and animal diseases. However, the reports concerning the effect of oxidative stress on pregnancy outcome are limited and scarce. The objective of this study was to determine the impact of oxidative stress on pregnancy outcome and to assess the antioxidant effect of vitamin C and E on oxidative stress parameters in blood and placental tissue samples in experimental pregnant animals model exposed to oxidative stress. Wister Albino rats were used in this work to investigate the effects of oxidative stress exposure (addition of H2O2 to the drinking water) on pregnancy outcome. Rats were divided into 5 groups, as follows: Group I (included 7 normal pregnant rats which served as control group). Group II (exposed to 1 % H2O2) included 7 pregnant rats, the rats were allowed to become pregnant and received (1% H2O2) in drinking water from day 7th till the day 19th of pregnancy. Group III (exposed to 3% H2O2) included 8 pregnant rats. Same as group 2, but the rats were exposed to a higher concentration of H2O2 (3%) in drinking water. Group IV (included 8 pregnant rats). Pregnant rats received vitamins C and E without induction of oxidative stress. Group V (included 8 pregnant rats).induction of oxidative stress by 1% H2O2 with vitamins supplementation in the pregnant rats. Serum total antioxidants capacity (TAC), serum and placental tissue oxidative stress biomarker; 8-iso prostaglandin F2α (8-Isoprostane) were measured using specific ELISA kits. Also placental tissues of pregnant rats were isolated and put directly in 10% formalin prepared for histopathological examination. Results revealed a significant decrease in the median values of the body weight and total serum antioxidants capacity (TAC) in groups II and III of rats compared with the control group. A significant higher median value of TAC obtained in the groups IV and V when compared with the control group. Significant higher levels of serum and tissue Isoprostane observed in both groups II and III compared with control group. Histopathological, oxidative stress induced macroscopically degenerative with microscopical appearance of vasculitis and hemorrhage within decidua. Data of the present study demonstrated that imbalance oxidative stress status in pregnant rats occurred due to exposure to oxidant, which played an important role in the pathogenesis of abnormal pregnancy outcome. In addition antioxidants supplementation (vitamins E and C) were valuable in reducing this stress.
Gut Microbiota Dysbiosis and Their Impact on Biochemical and Inflammatory Profiles in Cafeteria Diet Fed Sprague Dawley Rats  [PDF]
Reem Moath Alasmar, Kavitha Varadharajan, Muralitharan Shanmugakonar, Hamda A. Al-Naemi
Advances in Microbiology (AiM) , 2019, DOI: 10.4236/aim.2019.99047
Abstract: Gut microbiota plays a major role in regulating the host metabolism and immune system. However, the structure of microbiome population is altered constantly by diverse factors including diet and environment. In particular, the gut microbiome dynamics is influenced by diet composition and their associated metabolites. Many studies in the recent past reported on diet induced dysbiosis in the gut microbiome, the modulating ratio between Firmicutes and Bacteroidetes plays a central role in maintaining the microbiome diversity in the gut and their abundance regulates obese conditions. Although there are several reports on gut microbial dysbiosis (Firmicutes/Bacteroidetes) at phylum level but only few of them highlight at the genera level. In the present study, we focused more on the impact of cafeteria diet (CAF) with respect to the gut microbiome richness at the genera level in SD rats. Three weeks old Sprague Dawley (SD) rats were fed with normal chow diet and cafeteria diet (CAF). After 10 weeks, serum, tissue samples (small intestine and cecum), cecum fecal and fecal pellet were collected. Biochemical analysis from serum, Gene expression analysis of pro-inflammatory markers from tissues and microbiome analysis from fecal samples were analysed. CAF diet fed rat in the present study developed obesity with increased body weight, few of them developed the resistance to weight gain (WGR) and these animal shows significantly increased abundance of Bacteriodetes-Prevotella compared to obese animals. This study suggests that detailed research needed to address the contribution of microbiota abundance at the genera level. We further explored the influence of diet induced microbiota changes on immune response; increase in Bacteroidetes leads to increased LPS and this in turn elicit immune reaction in the gut. Moreover, variation in gut microbiota also affects the gut barrier function (Tight junction proteins) and increase metabolic endotoxemia that leads to activation of innate immune system and low-grade inflammation. Further studies on these lines targeting the microbiota changes in the gut at the genera level is warranted to gain more knowledge.
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