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RISS 인기검색어
- 검색키워드
- 저자 : Hamdy A. Hassan (검색결과 3 건)
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3D investigation on the impact of chips positions and number on their cooling inside cavity
Hamdy Hassan,N. Y. Abdel Shafey,Ziya Uddin,A. A. Hawwash 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.11
A 3D transient investigation of the cooling of electronic chips inside a cavity and enhanced by a finned heat sink is studied numerically. Moreover, the impact of the position and number of electronic chips on their cooling, heat transfer, and fluid flow by natural convectionradiation inside the cavity is presented. Radiation exchange between enclosure walls is considered. Furthermore, the impact of using multiple electronic chips having the same volume and power of one chip on its cooling and the process of heat transfer is investigated. A complete three-dimensional transient mathematical model for the studied physical model is introduced and solved by utilizing a finite difference numerical method. Experiments are conducted to validate the numerical solution which shows good agreement between experimental and numerical results. Findings show that neglecting radiation between cavity walls increases chip temperature by approximately 20 %. The best electronic chip position achieves minimum chip temperature when it is installed at the center of the cavity base plate. Using two and four electronic chips having the same volume and power of one chip decreases the flow eddies inside the cavity and the maximum temperature of one chip by about 25.3 % and 42.6 %, respectively.
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A New Hotbed for Extremism? Jihadism and Collective Insecurity in the Sahel
Hamdy A. Hassan 서울대학교 통일평화연구원 2020 Asian Journal of Peacebuilding Vol.8 No.2
Several jihadist groups sought a safe haven in the Sahel region following the defeat of Daesh in Syria and Iraq, making it a hotbed of terrorist activities. These groups have relied on crime, amongst other strategies, to survive and expand. Such strategies serve as the groups’ lifeblood and help them forge alliances with local actors. The appeal of radical jihadist discourse capitalizes on human insecurities as manifested in political, environmental, and demographic challenges. This article considers not only the new threats to human security in the Sahel, but also the need for a multidimensional, inclusive, dialogue-based solution. Promoting development and social cohesion centered on human security could achieve better results in the region than resorting to external military intervention.
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Kotb Eman A.,El-Shiekh Riham A.,Hassan Mariam,Abd-Elsalam Wessam Hamdy,El Tanbouly Nebal,El Senousy Amira Safwat 한국응용생명화학회 2024 Applied Biological Chemistry (Appl Biol Chem) Vol.67 No.-
Acne is a highly prevalent skin disease with a great psychological impact on patients as self-perception, self-confidence, and depression. This work aimed to develop an anti-acne preparation from active anti-bacterial medicinal plants to circumvent the severe side effects and drug resistance commonly reported with topical erythromycin anti-acne preparations. Essential oils: Salvia officinalis L. (sage), Rosmarinus officinalis L. (rosemary), Commiphora myrrha Nees Engl. (myrrh), Origanum majorana L. (marjoram), Pelargonium zonale L. L’Hér. ex Aiton (geranium) and Chrysanthemum morifolium Ramat. (chrysanthemum) were extracted by hydrodistillation and analyzed using gas chromatography/ mass spectrometry (GC/MS). The anti-acne activities of the oils against Cutibacterium acnes ATCC 6919 were evaluated by microdilution methods to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The most active essential oils were loaded in a film-forming nanogel prepared with chitosan, pluronic F127 and glycerol in the ratio of 3:1:1, prior to investigation in a murine acne in vivo model. Marjoram and chrysanthemum oils showed the highest antimicrobial activity against C. acnes (MIC = 0.156% v/v and 0.125% v/v, respectively). GC/MS of the actives showed that gamma-terpinene (26.46%) and terpinen-4-ol (22.24%) were the predominant constituents in marjoram, whereas chrysanthenone (32.79%) was the main component in chrysanthemum. The formulated essential oil-loaded film-forming nanogels of both oils exhibited significant anti-acne activity in mice via reducing the bacterial loads, activating the antioxidant nuclear factor erythroid 2–related factor 2 (Nrf2) pathway and inhibiting the inflammatory tumor necrosis factor-alpha (TNF-α) pathway. Further studies should be designed to evaluate the clinical evidence for the use of marjoram and chrysanthemum oil products in acne treatment.
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