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Exploring tree diversity and stand structure of savanna woodlands in southeastern Sudan

Journal of Arid Land 2020年第4期12卷 609-617页

作者： ahmed m.m.HASOBA ahmed A H SIDDIG Yousif E YAGOUB Faculty of Forest Sciences and Technology University of GeziraMadani 22212Sudan Faculty of Forestry University of KhartoumKhartoum North 13314Sudan Departm.nt of Environm.ntal Conservation University of Massachusetts AmherstAmherst 01003USA

Savanna woodlands in Sudan host great biodiversity, provide a plethora of ecosystem.goods and services to local com.unities, and sustain num.rous ecological functions. Although the im.ortance of the Acacia trees in these areas is well known, up-to-date inform.tion about these woodlands' diversity is lim.ted and changes in their woody vegetation com.osition, density, diversity and relative frequency are not m.nitored over tim.. This study explored tree diversity and stand stage structure in Nuara Reserved Forest, a typical savanna woodland ecosystem.in southeastern Sudan. A total of 638 circular sam.le plots(1000 m.2 for each) were established using a system.tic sam.ling grid m.thod. The distance between plots was 200 m. In each plot, all living trees with diam.ter at breast height(DBH) ≥5.00 cm.were identified and counted, and their DBH values were recorded. From.these data, tree com.osition, diversity, density and stage structure were assessed. There were 12,259 individual trees representing four species(Acacia seyal, Balanites aegyptiaca, Acacia Senegal and Acacia m.llifera) that belong to two fam.lies. The dom.nant species was Acacia seyal. Average tree density was 191 trees/hm.2 and the Shannon-Weiner index for trees diversity was 0.204. Overall, young trees com.rised 86.30% of the forest. The state of tree richness and density in the study area was low com.ared to other sim.lar environm.nts in the region and around the world. We recom.ended adoption of a proper m.nagem.nt system.that includes m.nitoring of woody vegetation diversity in this forest, and m.nagem.nt actions to enhance tree diversity and sustain ecosystem.services to local com.unities. In addition to care for the dom.nant Acacia seyal stands, m.re attention and conservation should be devoted to reestablishing Acacia senegal and Acacia m.llifera trees because of their high ecological and econom.c values for local com.unities.

关键词： species diversity stand structure savanna woodland ecosystem forest m.nitoring forest m.nagem.nt ecosystem.services Nuara Reserved Forest

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Effect of m.tal Contact and Rapid Therm.l Annealing on Electrical Characteristics of Graphene m.trix

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Chinese Physics Letters 2017年第10期34卷 65-69页

作者： S, Fahad m. Ali S. ahmed S. Khan S. Alam.S. Akhtar Advanced Electronics Laboratories International Islamic University Islamabad Pakistan Departm.nt of Physics Federal Urdu University of Arts Sciences & Technology Karachi Pakistan

Developm.nt of graphene field effect transistors （GFETs） faces a serious challenge of graphene interface to the dielectric m.terial. A single layer of intrinsic graphene has an average sheet resistance of the order of 1-5 kΩ/□. The intrinsic nature of graphene leads to higher contact resistance yielding into the outstanding properties of the m.terial. We design a graphene m.trix with m.nim.zed sheet resistance of 0.185 kΩ/□ with Ag contacts. The developed m.trices on silicon substrates provide a variety of transistor design options for subsequent fabrication. The graphene layer is developed over 400 nm.nickel in such a way as to analyze hypersensitive electrical properties of the interface for exfoliation. This work identifies potential of the design in the applicability of few-layer GFETs with less process steps with the help of analyzing the effect of m.tal contact and post-process annem.ng on its electrical fabrication.

关键词： Effect of m.tal Contact and Rapid Therm.l Annealing on Electrical Characteristics of Graphene m.trix

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m.lecular aspects of m.RS-CoV

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Frontiers of m.dicine 2017年第3期11卷 365-377页

作者： Ali A. Rabaan Ali m. Bazzi Sham.ah H. Al-ahmed Jaffar A. Al-Tawfiq m.lecular Diagnostic Laboratory Johns Hopkins Aramco HeaIthcare Dhahran 31311 Saudi Arabia m.crobiology Laboratory JohnsHopkins Aramco Healthcare Dhahran 3131i Saudi Arabia Specialty Paediatric m.dicine Qatif CentralHospitaL Qatif 32654 Saudi Arabia Specialty Internal m.dicine Johns Hopkins Aramco Healthcare Dhahran 31311 Saudi Arabia Indiana University School of m.dicine Indianapolis IN 46202 USA

m.ddle East respiratory syndrom. coronavirus （m.RS-CoV） is a betacoronavirus which can cause acute respiratory distress in hum.ns and is associated with a relatively high m.rtality rate. Since it was first identified in a patient who died in a Jeddah hospital in 2012, the World Health Organization has been notified of 1735 laboratory-confirm.d cases from.27 countries, including 628 deaths. m.st cases have occurred in Saudi Arabia. m.RS-CoV ancestors m.y be found in Old World bats of the Vespertilionidae fam.ly. After a proposed bat to cam.l switching event, transm.ssion of m.RS-CoV to hum.ns is likely to have been the result of m.ltiple zoonotic transfers from.drom.dary cam.ls. Hum.n-to-hum.n transm.ssion appears to require close contact with infected persons, with outbreaks m.inly occurring in hospital environm.nts. Outbreaks have been associated with inadequate infection prevention and control im.lem.ntation, resulting in recom.endations on basic and m.re advanced infection prevention and control m.asures by the World Health Organization, and issuing of governm.nt guidelines based on these recom.endations in affected countries including Saudi Arabia. Evolutionary changes in the virus, particularly in the viral spike protein which m.diates virus-host cell contact m.y potentially increase transm.ssion of this virus. Efforts are on-going to identify specific evidence-based therapies or vaccines. The broad-spectrum.antiviral nitazoxanide has been shown to have in vitro activity against m.RS-CoV. Synthetic peptides and candidate vaccines based on regions of the spike protein have shown prom.se in rodent and non-hum.n prim.te m.dels. GLS-5300, a prophylactic DNA-plasm.d vaccine encoding S protein, is the first m.RS-CoV vaccine to be tested in hum.ns, while m.noclonal antibody, m.36 has given prom.sing results in anim.l m.dels and has potential for use in outbreak situations.

关键词： m.RS-CoV Saudi Arabia spike protein transm.ssion evolution vaccine

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Effect of Colouring Process on Pitting Susceptibility of Austenitic Stainless Steel

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Journal of m.terials Science & Technology 2008年第3期24卷 400-406页

作者： S.S.m.hm.ud m.m.ahmed Chem.stry Departm.nt University College of Girls for ArtsScience and EducationAin Shams University

Colouring of the austenitic stainless steel alloy （20.45% Cr, 8.57% Ni） was carried out in NaNO3-KNO3 eutectic m.lt without and with additions of Na2O2, NaCl and their m.xtures at different tem.eratures ranging from.400-600℃, under open-circuit and galvanostatic anodic polarization conditions. The produced colours greatly depend on the thickness of oxide film., which in turn depends on the com.osition of the m.lten bath and its tem.erature. The m.re attractive, bright, adherent and uniform.coloured oxide film. can be obtained at 400, 450 and 500℃ in m.lten nitrate bath containing NaCl and Na2O2 m.xtures. The pitting corrosion susceptibility of the coloured oxide film. was tested in FeCl3 and NaCl as corrosive m.dia. The obtained results indicate that the pitting corrosion susceptibility of the coloured oxide film. greatly depends on the previous operating conditions of the colouring process of the stainless steel specim.ns such as the com.osition of m.lten bath, tem.erature and technique of colouring process.

关键词： Stainless steel alloy Pitting corrosion Colouring processes

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Density functional theory study of structural,electronic,and therm.l properties of Pt,Pd,Rh,Ir,Os and PtPdX(X=Ir,Os,and Rh)alloys

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Chinese Physics B 2016年第3期25卷 298-306页

作者： Shabbir ahmed m.ham.ad Zafar m.Shakilt m.A Choudhary Sim.lation Laboratory Department of Physicsthe Islamia University of BahawalpurBahawalpur 63100Pakistan o Departm.nt of Physics Hafiz Hayat CampusUniversity of GujratGujrat 50700Pakistan

The structural, electronic, m.chanical, and therm.l properties of Pt, Pd, Rh, Ir, Os m.tals and their alloys PtPdX （X = Ir, Os and Rh） are studied system.tically using ab initio density functional theory. The groundstate properties such as lattice constant and bulk m.dulus are calculated to find the equilibrium.atom.c position for stable alloys. The electronic band structure and density of states are calculated to study the electronic behavior of m.tals on m.king their alloys. The electronic properties substantiate the m.tallic behavior for all studied m.terials. The firstprinciples density functional perturbation theory as im.lem.nted in quasi-harm.nic approxim.tion is used for the calculations of therm.l properties. We have calculated the therm.l properties such as the Debye tem.erature, vibrational energy, entropy and constant-volum. specific heat. The calculated properties are com.ared with the previously reported experim.ntal and theoretical data for m.tals and are found to be in good agreem.nt. Calculated results for alloys could not be com.ared because there is no data available in the literature with such alloy com.osition.

关键词： electronic structural and therm.l properties platinum.group m.tals

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Phenolic and nuntritional profiles, and antioxidant activity of grape pom.ces and seeds from.Lacrim. di m.rro d'Alba and Verdicchio varieties

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FOOD BIOSCIENCE 2023年第3期53卷 2731-2740页

作者： Abouelenein, Doaa m.stafa, ahmed m. Caprioli, Giovanni Ricciutelli, m.ssim. Sagratini, Gianni Vittori, Sauro Univ Cam.rino Sch Pharm Chem Interdisciplinary Project CHIP Via Madonna Carceri I-62032 Camerino Italy Zagazig Univ Fac Pharm Dept Pharmacognosy Zagazig 44519 Egypt

Grape pom.ce contains high am.unts of bioactive com.ounds, m.inly polyphenols, with different concentrations depending on several factors: grape variety, vinification procedures, even within the sam. cultivar variation m.y be due to the geographic regions and wine vintage. Therefore, phenolic, antioxidant, m.cro- and m.cronutritional com.osition of wine waste (pom.ce and seed) originating from.Lacrim. di m.rro d'Alba red grape variety and pom.ce of Verdicchio white variety were evaluated for the first tim.. LC-m./m. analysis showed the presence of 32 phenolic com.ounds. The phenolic profile was different in pom.ce of both varieties: white grape pom.ces showed the predom.nance of flavan-3-ols, while anthocyanins were predom.nant in red pom.ces. Com.aring seeds and pom.ce of Lacrim. di m.rro d'Alba, catechin and epicatechin are representative com.ounds in red grape seeds, while m.lvidin-3-galactoside and petunidin-3-glucoside are the m.st abundant com.ounds in pom.ce of all wineries. Highest TPC and antioxidant activities determ.ned by UV-vis spectrophotom.ter were observed in seed sam.les. High dietary fibers, polyunsaturated fatty acids, m.nerals and protein contents were observed in all sam.les. Wine byproducts of both grape varieties appeared to be a good source of phenolic and nutritional com.ounds;therefore, they could be a cheap alternative for phenolics production and developm.nt of new functional foods.

关键词： Lacrim. di m.rro d 'Alba Red grape variety White grape variety Verdicchio Grape pom.ce Grape seeds Phenolic profile Nutritional profile Antioxidant

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Assessm.nt of clay stiffness and strength param.ters using index properties

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Journal of Rock m.chanics and Geotechnical Engineering 2018年第3期10卷 579-593页

作者： Sayed m.ahmed Structural Engineering Departm.nt Ain Shams University

A new approach is developed to determ.ne the shear wave velocity in saturated soft to firm.clays using m.asurem.nts of the liquid lim.t, plastic lim.t, and natural water content with depth. The shear wave velocity is assessed using the site-specific variation of the natural water content with the effective m.an stress. Subsequently, an iterative process is envisaged to obtain the clay stiffness and strength *** at-rest earth pressure coefficient, as well as bearing capacity factor and rigidity index related to the cone penetration test, is also acquired from.the analyses. Com.arisons are presented between the m.asured clay param.ters and the results of corresponding analyses in five different case studies. It is dem.nstrated that the presented approach can provide acceptable estim.tes of saturated clay stiffness and strength param.ters. One of the m.in privileges of the presented m.thodology is the site-specific procedure developed based on the relationships between clay strength and stiffness param.ters, rather than adopting direct correlations. Despite of the utilized iterative processes, the presented approach can be easily im.lem.nted using a sim.le spreadsheet, benefiting both geotechnical researchers and practitioners.

关键词： Soft to firm.clays Atterberg lim.ts Shear wave velocity Sm.ll-strain shear m.dulus Constrained m.dulus Undrained shear strength Effective friction angle Cone penetration test

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An Integrated Fram.work for Cloud Service Selection Based on BOm.and TOPSIS

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Com.uters, m.terials & Continua 2022年第8期72卷 4125-4142页

作者： ahmed m.m.stafa Com.uter and System. Engineering Departm.nt Faculty of Engineering at HelwanHelwan UniversityCairo11795Egypt

m.ny businesses have experienced difficulties in selecting a cloud service provider(CSP)due to the rapid advancem.nt of cloud com.uting services and the proliferation of *** independent criteria should be considered when evaluating the services provided by different *** is a case of m.lti-criteria decision-m.king(m.Dm..This paper presents an integrated m.Dm.cloud service selection fram.work for determ.ning the m.st appropriate service provider based on the best only m.thod(BOm.and technique for order of preference by sim.larity to ideal solution(TOPSIS).To obtain the weights of criteria and the relative im.ortance of CSPs based on each criterion,BOm.perform. pairwise com.arisons of criteria and also for alternatives on each criterion,and TOPSIS uses these weights to rank cloud *** evaluation and validation of the proposed fram.work have been carried out through a use-case m.del to prove its efficiency and ***,the developed fram.work was com.ared with the analytical hierarchical process(AHP),a popular m.Dm.approach,based on two perspectives:efficiency and *** to the research results,the proposed fram.work only requires 25%of the com.arisons needed for the AHP ***,the proposed fram.work has a CR of 0%,whereas AHP has 38%.Thus,the proposed fram.work perform. better than AHPwhen it com.s to com.utation com.lexity and consistency,im.lying that it is m.re efficient and trustworthy.

关键词： Cloud com.uting(CC) m.ltiple-criteria decision-m.king(m.Dm. cloud service providers(CSPs) analytical hierarchical process(AHP) the best only m.thod(BOm. technique for order of preference by sim.larity to ideal solution(TOPSIS)

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Com.arison of outcom.s between early and delayed weight bearing following lower lim. free flaps:an 18-m.nth single-center study

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Plastic and Aesthetic Research 2023年第1期10卷 656-662页

作者： m.jid Al-Khalil m.nuela Rom.n ahmed emam Nicholas m.rsden Welsh Centre for Burns&Plastic Surgery Morriston HospitalSwansea SA66NLUnited Kingdom m.jor Traum. Centre University Hospital of WalesCardiff CF144XWUnited Kingdom

Aim.Post-operative protocols following lower lim. free flap surgery are not well defined,with a lack of consensus in the literature around lim. dependency and weight *** aim.was to com.are the com.lication rate for lower lim. free flaps before and after the introduction of an enhanced lower lim. free flap protocol with earlier dangling(day 3 *** 4)and weight bearing(day 5 *** 14)post lower lim. free flap ***:All lower lim. free flaps between June 2020-January 2022 were identified from.a departm.ntal flap *** data were collected from.the com.rehensive lower lim. free flap database,m.dical notes,and electronic *** prescribed an extended non-weight-bearing period due to the m.thod of bone fixation were ***:A total of 37 patients,15 pre-and 22 post-enhanced protocol,were identified for *** m.an age was 43(17-72)with a m.F of 3:*** was no difference in the type of flap reconstruction between groups,with the anterolateral thigh flap being the m.st com.on in both *** differences were identified in the num.er of com.lications related to dependency/weight bearing before and after the introduction of the enhanced protocol,with the m.an length of stay reduced from.12.1 to 10.6 days(P=0.34).Conclusion:The new enhanced protocol rem.ins the standard of care in our unit,as we dem.nstrated a reduction in length of stay with no difference in com.lication rates following early weight bearing after lower lim. free flap surgery.

关键词： Lower lim. reconstruction free flap free tissue transfer weight bearing post-operative com.lications

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Voltage im.alance m.tigation in an active distribution network using decentralized current control

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Protection and Control of m.dern Power System. 2023年第2期8卷 68-84页

作者： ahmed m.m.Nour ahmed A.Helal m.gdi m.El-Saadawi ahmed Y.Hatata Alexandria Higher Institute of Engineering and Technology(AIET) AlexandriaEgypt Departm.nt of Electrical and Control Engineering Arab Academy for Science and Technology and Maritime TransportAlexandriaEgypt Departm.nt of Electrical Engineering Faculty of EngineeringMansoura UniversityMansouraEgypt Departm.nt of Electrical Engineering College of EngineeringShaqra UniversityShaqraKingdom of Saudi Arabia

Voltage im.alance(VI)is caused by the difference in connected single-phase load or generation in a low voltage distribution network(DN).VI increase in a sm.rt distribution grid is due to the current practice of increasing single-phase distributed generators such as photovoltaic(PV)*** paper proposes a decentralized control m.thod to m.tigate VI using distributed batteries included in sm.rt grid interfaced residential PV *** m.tigate VI using the batteries in this way,five challenges m.st be overcom.,i.e.,equalizing all battery stress currents within the DN,m.tigating VI in abnorm.l conditions such as signal loss am.ng bus controllers,being im.une from.the distorted feedback m.asurem.nts,m.nim.zing the steady-state error at different loads,and overcom.ng the insufficient num.er or capacity of the distributed batteries at the sam. *** fuzzy logic controllers(FLC)are proposed at each bus to overcom. these five tasks based on a decentralized control *** proposed decentralized control based on FLC is com.ared with centralized control based on a PI *** proposed control m.thod is tested and verified using sim.lations in the m.TLAB/Sim.link software,and the results validate the ability of the schem. to alleviate VI on a sm.rt distribution network under both norm.l and abnorm.l conditions.

关键词： Fuzzy controller Distributed batteries Decentralized control Voltage im.alance Distributed PV

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