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Design and Analysis of an OSA-BR MAC Protocol for Cognitive Radio Ad Hoc Networks

International Journal of Communications, Network and System Sciences 2014年第7期7卷 223-234页

作者： Hassan Al-Mahdi Mohamed Wahed safa abd el-aziz Faculty of Sciences and Arts Al Jouf UniversityAl QuryyatKSA Faculty of Computers and Information Suez Canal UniversityIsmailiaEgypt

Cognitive Radio (CR) is a new communication network paradigm introduced to solve the problems of spectrum scarcity and inefficient spectrum usage. Basically, it allows the Secondary Users (SUs) to utilize the Licensed Channels (LCs) of the Primary Users (PUs) in an opportunistic manner without causing any harmful interference to the PUs. However, there are many challenges associated with cognitive radio networks, such as the CR Medium Access Control (CR-MAC) protocols. An important issue for CR-MAC protocols is to identify whether the spectrum is licensed or unlicensed. In addition, the sudden appearance of the PU is the most important feature of the distributed CR-MAC protocols. In this paper, a multichannel CR-MAC protocol, which reacts efficiently to the appearance of the PUs, is developed. The proposed protocol is named Opportunistic Spectrum Access with backup channel and Buffered data with Resume (OSA-BR). The OSA-BR is an unaided rendezvous, asynchronous, and contention-based MAC protocol. The proposed protocol operates in heterogeneous environment, where the SUs utilize both LCs and unlicensed channel (ULs) and the activities of the Classical Users (CUs) are taken into consideration. In addition, the concept of the backup channel and the buffer with resume are introduced. The simulation results show that OSA-BR accomplishes 35% throughput gain over the SWITCH protocol and 55% over other CR-MAC protocols.

关键词： Rendezvous Cognitive Radio Ad Hoc Analytical Model

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The potency of N,N′-diphenyl-1,4-phenylenediamine and adiposederived stem cell co-administration in alleviating hepatorenal dysfunction complications associated with type 1 diabetes mellitus in rats

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BIOCelL 2023年第8期47卷 1885-1895页

作者： HANY M.abd el-LATEEF safa H.QAHL EMAN FAYAD SARAH A.ALTALHI IBRAHIM JAFRI el SHAIMAA SHABANA MARWA K.DARWISH REHAB MAHER SAAD SHAABAN SHADY G.el-SAWAH Department of Chemistry College of ScienceKing Faisal UniversityAl-AhsaSaudi Arabia Chemistry Department Faculty of ScienceSohag UniversitySohagEgypt Department of Biology College of ScienceUniversity of JeddahJeddahSaudi Arabia Department of Biotechnology College of ScienceTaif UniversityTaifSaudi Arabia Fellow of Biochemistry Genetic UnitChildren HospitalFaculty of MedicineMansoura UniversityMansouraEgypt Chemistry Department(Biochemistry Branch) Faculty of ScienceSuez UniversitySuezEgypt Department of Clinical Laboratories Sciences College of Applied Medical SciencesShaqra UniversityRiyadhSaudi Arabia Biology Department Faculty of ScienceMansoura UniversityMansouraEgypt Department of Chemistry Organic Chemistry DivisionCollege of ScienceMansoura UniversityMansouraEgypt Zoology Department Faculty of ScienceArish UniversityNorth SinaiEgypt

Background:The increasing occurrence of diabetes mellitus(DM)noted worldwide has considerably elicited concern in the recent *** is associated with elevated vascular complications,morbidity,mortality,and poor quality of *** this context,mesenchymal stem cells(MSCs)have shown significant therapeutic potentialities in managing and curing type 1 DM owing to their self-renewable,immunosuppressive,and differentiation *** investigated the potential action of N,N′-diphenyl-1,4-phenylenediamine(DPPD),a well-known synthetic antioxidant to enhance the therapeutic ability of the adipose-derived stem cells(AD-MSCs)in alleviating kidney and liver complications in diabetic ***:Over the four weeks of experiments,albino male rats(n=36)were split into six test groups:control,DPPD(250 mg/kg,i.p.),STZ-diabetic(D),D+DPPD,D+AD-MSCs(1×10^(6)cell/rat,i.v.),and D+AD-MSCs+DPPD treated ***:Significant declines in the renal and hepatic oxidative stress markers(MDA,ROS,and AGEs)were observed coupled with a significant elevation in many antioxidant marker levels(GSH,SOD,CAT,GPx,HO-1,and TAC)in the diabetic rats treated with either DPPD or AD-MSCs or their co-administered injection compared to the diabetic untreated *** was suggested to be the leading cause of amelioration of the kidney functions(as measured by urea,uric acid,and creatine levels)and liver functions(as evidenced by the levels of AST,ALT,ALP,bilirubin,total proteins,albumin,and globulins).Conclusion:DPPD and AD-MSCs co-administration showed superior results in terms of the enhancement of the relative hepato-renal function,indicating the beneficial role of DPPD supplementation in increasing the therapeutic potential of AD-MSCs.

关键词： Antioxidants Diabetic nephropathy DPPD Oxidative stress Stem cells

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