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- 저자 : KAMAR, Saifaldin Hashim (검색결과 12 건)
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Kamar Shah Ariffin,Jimoh Abdullateef Onimisi,Roniza Ismail,Norlia Baharun,Hashim Bin Hussin 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.9
Various techniques and approaches have been designed to synthesize precipitated calcium carbonate. We used a continuous sprayed-mist technique that induced spontaneous precipitation reaction of the droplets with the higher surface area when in contact with the gas. The effects of optimum reactant concentration, gas flow rate, and reactant feeding rate including reaction conditions were investigated. The effectiveness of the techniques was scrutinized by analyzing the resultant PCC characteristics, especially the particle phase morphology and size distribution using XRD, FTIR, and SEM. The variation of initial concentration of milk of lime with different gas flow rate was studied. Experimental results, as well as XRD and FTIR, indicated that all the products produced were favorable for the formation of calcite. SEM revealed that the morphologies of PCC were all rhombohedral and tended to adhere to each other (twinning). It was found that production of PCC by using spray-mist method is suitable for lower initial concentration of Ca(OH)2 and higher gas flow rate only.
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Compact Wireless IPT System Using a Modified Voltage-fed Multi-resonant Class EF₂ Inverter
Mohammad Kamar Uddin,Saad Mekhilef,Gobbi Ramasamy 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1
Wireless inductive power transfer (IPT) technology is used in many applications today. A compact and high-frequency primary side inverter is one of the most important parts of a WPT system. In this study, a modified class EF-type voltage-fed multi-resonant inverter has been proposed for WPT application at a frequency range of 85–100 kHz. Instead of an infinite input choke inductor, a resonant inductor is used to reduce loss and power density. The peak voltage stress across the MOSFET has been reduced to almost 60% from a class-E inverter using a passive clamping circuit. A simple yet effective design procedure has been presented to calculate the various component values of the proposed inverter. The overall system is simulated using MATLAB/SimPowerSystem to verify the theoretical concepts. A 500-W prototype was built and tested to validate the simulated results. The inverter exhibited 90% efficiency at nearly perfect alignment condition, and efficiency reduced gradually with the misalignment of WPT coils. The proposed inverter maintains zero-voltage switching (ZVS) during considerable load changes and possesses all the inherent advantages of class E-type inverters.
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Nur Hafizah Kamar Affendi,Jumanah Babiker,Mohd Yusmiaidil Putera Mohd Yusof 대한치주과학회 2023 Journal of Periodontal & Implant Science Vol.53 No.6
Purpose: This study aimed to quantify alveolar bone morphology, demonstrate the relationship between tooth angulation and alveolar bone thickness, and introduce a new classification for anterior mandibular teeth related to immediate implant placement (IIP). Methods: Cone-beam computed tomography (CBCT) images of 211 anterior mandibular teeth were analyzed in sagittal slices to measure the thickness of the facial alveolar bone crest (FAB1) and apex (FAB2), and the lingual alveolar bone crest (LAB1) and apex (LAB2). Tooth angulation was classified as 1°–10°, 11°–20°, and >20° according to the tooth’s long axis and alveolar bone wall. Spearman correlation coefficients were used to evaluate correlations between the variables. Results: FAB1 and LAB1 were predominantly thin (<1 mm) (84.4% and 73.4%, respectively), with the lateral incisors being thinnest. At the apical level, FAB2 and LAB2 were thick in 99.5% and 99.1% of cases, respectively. Significant differences were documented in FAB2 (P=0.004), LAB1 (P=0.001), and LAB2 (P=0.001) of all mandibular teeth. At all apical levels of the inspected teeth, a significant negative correlation existed between TA and FAB2. Meanwhile, TA showed a significant positive correlation with LAB2 of the lateral incisors and canines. These patterns were then divided into class I (thick facial and lingual alveolar bone), class II (facially inclined teeth) with subtype A (1°–10°) and subtype B (11°–20°), and class III (lingually inclined teeth) with subtype A (1°–10°) and subtype B (11°–20°). Conclusions: Mandibular anterior teeth have predominantly thin facial and lingual crests, making the lingual bone apical thickness crucial for IIP. Although anchorage can be obtained from lingual bone, tooth angulation and tooth types had an impact on IIP planning. Hence, the new classification based on TA and alveolar bone wall may enable rational clinical planning for IIP treatment.
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Uddin, Mohammad Kamar,Mekhilef, Saad,Ramasamy, Gobbi The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1
Wireless inductive power transfer (IPT) technology is used in many applications today. A compact and high-frequency primary side inverter is one of the most important parts of a WPT system. In this study, a modified class EF-type voltage-fed multi-resonant inverter has been proposed for WPT application at a frequency range of 85-100 kHz. Instead of an infinite input choke inductor, a resonant inductor is used to reduce loss and power density. The peak voltage stress across the MOSFET has been reduced to almost 60% from a class-E inverter using a passive clamping circuit. A simple yet effective design procedure has been presented to calculate the various component values of the proposed inverter. The overall system is simulated using MATLAB/SimPowerSystem to verify the theoretical concepts. A 500-W prototype was built and tested to validate the simulated results. The inverter exhibited 90% efficiency at nearly perfect alignment condition, and efficiency reduced gradually with the misalignment of WPT coils. The proposed inverter maintains zero-voltage switching (ZVS) during considerable load changes and possesses all the inherent advantages of class E-type inverters.
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Samaa Samir Kamar,Noha Samir Abdel Latif,Mohamed Fathi Mohamed Elrefai 대한해부학회 2020 Anatomy & Cell Biology Vol.53 No.3
Gastric ulcer is one of the most serious diseases. Nebivolol (Neb), a β1-blocker, exhibits vasodilator and anti-oxidative properties, simvastatin (Sim) antihyperlipidemic drug, exhibits anti-oxidative, anti-inflammatory properties and promote endogenous nitric oxide (NO) production. The aim of this study was to evaluate the gastroprotective effects of Neb and Sim against cold restraint stress (CRS)-induced gastric ulcer in rats. Rats were restrained, and maintained at 4°C for 3 hours. Animals were divided into six groups; control group, CRS group, and four treatment groups received ranitidine (Ran), Neb, Sim and both Neb and Sim. Treatments were given orally on a daily basis for 7 days prior to CRS. The gastroprotective effects of Neb and Sim were assessed biochemically by measuring variations in prostaglandins E2, NO, reduced glutathione and malondialdehyde, and functionally by estimating force of contractions of isolated rat fundus in the studied groups in response to acetylecholine stimulation and morphologically using hematoxylin and eosin staining, periodic acid Schiff’s reaction and immunohistochemistry for cyclooxygenase 2 in gastric mucosa. CRS caused significant ulcerogenic effect. Alternatively, pretreatment with Ran, Neb, and Sim significantly corrected biochemical findings, pharmacological and histological studies.
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Samaa Samir Kamar,Mostafa Hasan Baky,Abeer Ibraheem Omar 대한해부학회 2020 Anatomy & Cell Biology Vol.53 No.2
A 5-fluorouracil (5-FU) is used for cancer treatment despite its cytotoxic sequelae on healthy cells, especially the rapid proliferating ones. Intestinal mucositis is one of the most frequent chemotherapeutic debilitating sequelae. Rhubarb (Rh), an ancient herb, is known for its curing effect on gastrointestinal complications. This study aims to detect the role of aquaporin-4 (AQP-4), tumour necrosis factor-α (TNF-α), nuclear factor-kappa B (NF-κB), and matrix metalloproteinase-9 (MMP-9) in 5-FU-induced ileal histological and biochemical changes and the potential therapeutic effect of Rh water extract on these changes in rats. A 45 rats were divided into 3 groups; control, 5-FU (single intraperitoneal injection of 150 mg/kg/rat) and Rh-treated (oral 20 mg/kg/day/rat for 8 days). The change in animals’ weight, incidence of diarrhoea and AQP-4 and TNF-α values in ileal homogenates were measured. Ileal sections were subjected to hematoxylin and eosin stain, periodic acid Schiff (PAS)-reaction and MMP-9, NF-κB and AQP-4 immunohistochemical staining. A 5-FU group revealed marked ileal mucosal damage associated with a significant decrease in the mean body weight, AQP-4 level and area percent of PAS and AQP-4 positive reaction. Significant increase in the mean incidence of diarrhoea, TNF-α value and area percent of MMP-9 and NF-κB was detected. These changes were significantly corrected with Rh administration. A 5-FU resulted in severe ileal mucositis through TNF-α, NF-κB, MMP-9, and AQP-4 disturbances. Rh treatment was highly effective in preventing such mucositis.
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Sherif A,Kamar,Hany W,Abdel Malak,Shereen Adel Saad 대한해부학회 2020 Anatomy & Cell Biology Vol.53 No.3
Energy drinks are available worldwide and frequently consumed to increase energy level and compensate lack of sleep. Energy drinks consumers aim to improve their cognitive functions. Red Bull is the most popular energy drink consumed in Egypt. However, the link between the impact of energy drinks on the structure of hippocampal cornu ammonis 1 (CA1) and dentate gyrus (DG), a highly vulnerable brain regions to various insults, has not yet documented. To study the effect of energy drinks on structure of hippocampal CA1 and DG of adult male albino rats. Twenty one adult male albino rats were divided into three groups; group I control group, groups II and III received Red Bull, with a dose of 3.75 ml/kg/day orally using gastric tube for four and eight consecutive weeks respectively. At the end of the experiment, brains were dissected and hippocampal specimens were processed for histopathological and immunohistochemical studies. Histopathological examination of hippocampal sections in group II revealed vacuoles, decrease thickness of pyramidal cell layer with irregular dark or ghost nuclei. However, changes were more severe in group III with cracks in pyramidal cell layer, massive vacuolation and signet ring cells. Moreover, star shaped astrocytes and glial fibrillary acidic protein immuno-reactivity were more abundant in group III than in group II. Caffeinated energy drinks produced neurodegenerative changes and reactive astrocytosis in hippocampal CA1 and DG of adult male albino rats. These changes were duration-dependent being more severe in longer duration of intake.
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TAWFIK, Omar Ikbal,KAMAR, Saifaldin Hashim,BILAL, Zaroug Osman Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.3
The paper examines the impacts of the various sustainability dimensions on the financial performance of commercial banks in three Arab countries. Three dimensions have been considered as constitutive of the term sustainable development (social, economic, and environmental). The relationship between the sustainability dimensions of companies and accounting indicators was analyzed. The main hypothesis posits that the dimensions of sustainability do not have a significant and positive effect on the financial performance of the commercial banks. The study population consisted of commercial banks operating in three Arab countries (Oman, United Arab Emirates, and Jordan); the period of the study is from 2007 to 2018. The data were collected from the financial reports and sustainability reports of each bank through the Internet. The overall results of the study showed a moderately positive relationship between all sustainability dimensions and the banks' financial performance. The main contribution of the research is to study the dimensions of sustainability reports as contained in the Global Reporting Initiative (GRI-G4) and their impacts on the financial performance of commercial banks. Thus, this research will contribute to increasing the interest of the banks in sustainable development in a context where this research in Arab countries is scarce.
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