Browsing by Author "Hamed A.R."

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    Multiple Debris Orbital Collision Avoidance
    (IEEE Computer Society, 2019) Hamed A.R.; Badawy A.; Omer A.A.; Ashry M.; Hussein W.M.; Egyptian Armed Forces; Sherok city; Cairo; Egypt; MSA; October University for Modern Sciences and Arts; Cairo; Egypt; Mechanical Engineering Department; MTC; Cairo; Egypt; Egyptian Armed Forces; Cairo; Egypt; Egyptian Armed Forces; Sheraton square; Cairo; Egypt
    Recently, Mission safety become an important concern because of the exponentially increment of space objects crossing or accompany the orbit. In such a situation the risk value becomes more and more as these controlled and uncontrolled objects increase. Therefore, mission control centers depend on organizations as joint space operation center to use their supplied information to schedule a smart plan to minimize the orbit risk. This paper proposes a new technique in the field of satellite safe trajectory incorporating orbital separation distance between different orbiting objects in artificial potential field method rather than position difference as in many cases the difference between them is enormous. Satellite surroundings are represented by artificial field where counterpart objects are represented by repulsive potentials, and future predicted path as an attractive field. Therefore, prospective planned maneuver considers all surrounding objects with different probability within the same algorithm. The proposed method is then applied to a real case between a Chinese 'cz-4' and the United States 'DMSP 5D-2 F7' satellites and show the results before and after applying the algorithm with calculations of the velocity required to escape risk situation and maintain the necessary orbital parameters. Finally, a comparative study is implemented to determine the effectiveness of the proposed method compared to the well-known Hohmann maneuver. � 2019 IEEE.
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    Role Phytochemicals Play in the Activation of Antioxidant Response Elements (AREs) and Phase II Enzymes and Their Relation to Cancer Progression and Prevention
    (Elsevier B.V., 2018) Ezzat, Shahira M; El-Halawany A.M.; Hamed A.R.; Abdel-Sattar E.; Department of Pharmacognosy; Faculty of Pharmacy; Cairo University; Cairo; Egypt; Pharmacognosy Department; Faculty of Pharmacy; October University for Modern Science and Arts (MSA); 6th October; Egypt; Phytochemistry Department; National Research Centre; Giza; Egypt; Biology Unit; Central Laboratory for Pharmaceutical and Drug Industries Research Division; National Research Centre; Giza; Egypt
    Chemoprevention can be defined as a means of controlling cancer in which the incidence of the disease can be entirely prevented, slowed down, or reversed. Chemoprevention is acquiring great attention because it is a cost-effective alternative to cancer treatment, such as chemotherapy or radio-therapeutic programs, which should reduce the burden on local and global economies. There is increasing interest in studying the chemoprevention potentiality of natural compounds against cancer as a result of the reduced cancer risk in people who consume high amounts of phytochemicals in their diet. Chemoprevention may involve the interruption or reversal of the initiation and progression of the disease by setting targets with the goal of preventing end stage invasiveness and metastasis. The initiation stage of cancer can be stopped by preventing reactive oxygen species and/or carcinogen activity (i.e., scavenging free radicals or trapping carcinogens) or by inhibiting their metabolic activation, thereby suppressing their interaction with cellular macromolecular targets, such as DNA, RNA, and proteins. This can be achieved by inducing of a set of phase II detoxifying and antioxidant enzymes, such as the chemopreventive marker NAD(P)H:quinone oxidoreductase 1 (NQO1) and heme oxygenase (HO-1). NQO1 is a ubiquitous flavoenzyme that plays a crucial role in protecting cells from endogenous and exogenous oxidative stressors by catalyzing two- and four-electron reductions of these substrates to their hydroquinone forms. The expression of NQO1 in different tissues is regulated by antioxidant response elements (AREs) under both basal and oxidative stress conditions. NQO1 is known to be regulated by nuclear factor erythroid-derived related factor 2 (Nrf2), which belongs to the basic leucine zipper transcription factor family, and binds to AREs, leading to the expression of many cytoprotective and antioxidant genes. Since Nrf2 binds to AREs and regulates the expression and induction of NQO1, Nrf2 knockout causes a reduction in the constitutive expression of NQO1 and impairs its induction. Several vegetables and fruits, including blueberries, cocoa beans, cabbage, broccoli, and cauliflower, are among the most protective agents against cancer. This is specifically due to their high content of active phytochemicals, such as sulforaphanes, isothiocyanates, polyphenols, and flavonoids. Upon entering cells these chemicals can directly counteract free radicals and induce electrophilic stress signals that trigger proteins linked to diverse cellular signaling pathways. This capability involves activation of the NQO1 gene and other phase II detoxification genes by activating the Nrf2/Kelch-like ECH-associated protein (Keap1) complex system. This chapter reports the chemopreventive effect of dietary components or their phytochemicals by activating the Nrf2�Keap1/ARE pathway and inducing NQO1. � 2018 Elsevier B.V.