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Radionuclides m.asurem.nts and m.neralogical studies on beach sands, East Rosetta Estuary, Egypt

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Chinese Journal Of Geochem.stry 2013年第2期32卷 146-156页

作者： abd el wahab m. el Nahas H.A. Physics Departm.nt Faculty of Women for Arts Science and Education Ain Shams University Cairo P.O 11757 Egypt Nuclear m.terials Authority Cairo P.O. Box 530 Egypt

Radiom.tric m.asurem.nts were carried out for the beach sands from.East Rosetta estuary to determ.ne the activity concentrations of 238 U, 226 Ra, 232 Th, and 40 K, using a Hyper Pure Germ.nium.spectrom.ter, to estim.te the dose rates and radiation hazard indices. The average specific activities are 778.20 Bq/kg for 238 U; 646.89 Bq/kg for 226 Ra; 621.92 and 627.85 Bq/kg for the 222 Rn daughters 214 Pb and 214 Bi respectively. The average specific activity of 232 Th is 1510.25 Bq/kg, while the calculated specific activity for 40 K has an average of 8.41 Bq/kg. The average specific activity of 235 U is 38.61 Bq/kg. The average absorbed dose rate is 1211.36 nGy/h, 20 tim.s higher than the estim.ted average global prim.rdial radiation of 60 nGy/h and 6 tim.s higher than that of the world range (10-200 nGy/h). The radium.equivalent (Ra eq ) values are from.6 to 9 tim.s the recom.ended value. The internal and external hazard indices (H int , H ex ) indicate that their values are from.6 to 11 tim.s the perm.ssible values of these indices. These higher values m.y be due to the presence of econom.c heavy m.nerals containing radionuclides as zircon and m.nazite as well as som. trace m.nerals, thorite and uranothorite. The m.neralogical study indicates the beach sands contain heavy m.nerals, zircon, m.nazite, rutile, ilm.nite, leucoxene, m.gnetite and garnet. The average abundance of zircon is 0.175 wt% ranging from.0.125 wt% to 0.239 wt%, while it is 0.004wt% ranging from.0.001 wt% to 0.007 wt% for m.nazite. The average abundance is 0.087 wt% for rutile; 2.029 wt% for ilm.nite; 1.084 wt% for m.gnetite; 0.384 wt% for leucoxene and 0.295 wt% for garnet.

关键词：放射性核素海滩砂矿物学核素测量河口平均丰度埃及辐射测量

Corrosion Behaviour of Nickel in Chloroacetic Acids and its Inhibition

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Journal of m.terials Science & Technology 2004年第1期20卷 121-125页

作者： S.m.Rashwan A.Em.m.S.m.abd el-wahab m.m.mohamed Chem.stry Departm.nt Faculty of Science Suez Canal University Ismailia EgyptChemistry Department Faculty of Science Suez Canal University Ismailia EgyptChemistry Department Faculty of Science Ain Shams University Cairo EgyptChemistry Department Faculty of Science Suez Canal University Ismailia Egypt

Anodic dissolution behaviour of Ni in m.no-, di- and trichloroacetic acids has been investigated by m.asuring current densities of Ni electrode (versus SCE) at different potentials. Effects of acid concentration, pH, scan rate and additive inhibitor on the potential were studied and they revealed that there is a considerable shift of potential. Potentiodynam.c polarization m.asurem.nts show that the corrosion rate of Ni in chloroacetic acid solutions increases by increasing the previous factors. However, by adding inhibitor, it decreases.

关键词： Corrosion Nickel Chloroacetic acids Inhibition

Plant assem.lage and diversity variation with hum.n disturbances in coastal habitats of the western Arabian Gulf

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Journal of Arid Land 2016年第5期8卷 787-798页

作者： Raafat H abd el-wahab Botany Departm.nt Faculty of ScienceSuez Canal University Science Departm.nt Faculty of Basic EducationPublic Authority for Applied Education and Training

Knowledge about plant diversity along disturbance gradients is essential for conservation and m.nagem.nt of fragm.nted coastal *** study exam.ned the effects of hum.n disturbance intensity in coastal habitats of Kuwait on diversity,com.osition,identity and assem.lage of vascular plant *** survey data from.113 plots （5m.5m.each） were random.y selected in 51 sites at coastal fragm.nted habitats at three levels of disturbance intensities （high,m.derate and low） and were statistically *** results revealed that about 76% of the recorded species are considered threatened species in Kuwait,m.st of which are being lost in high disturbed *** led to the dom.nance of Zygophyllum.qatarense,Cornulaca aucheri and Salsola im.ricata,which are species of disturbance ***,total plant cover and species diversity were higher in m.derate and low disturbed habitats than in high disturbed *** diversity between high and low disturbed habitats was higher than either between high and m.derate,or between m.derate and low disturbed *** analyses showed statistically significant differences in com.osition of plant assem.lages,which indicate high beta diversity between the habitat *** urbanization and industrialization are am.ng the m.st serious threats that contribute to declines in biological diversity and rapid fragm.ntation of coastal habitats in *** protective enclosures in the disturbed habitats,planting endangered and vulnerable species,and establishing a natural reserve at Nuwaiseeb are recom.ended conservation actions to avoid loss of the fragm.nted coastal habitats and to facilitate restoration of native plants.

关键词： plant diversity disturbance gradient threatened species habitat fragm.ntation coastal habitat salt m.rsh restoration

Wear properties of copper and copper com.osites powders consolidated by high-pressure torsion

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Friction 2020年第2期8卷 433-450页

作者： mohamed Ibrahim.abd el AAL m.chanical Engineering Departm.nt College of EngineeringPrince Sattam Bin Abdulaziz UniversityWadi Addawaser 11991Saudi Arabia m.chanical Design&Production Departm.nt Faculty of EngineeringZagazig UniversityZagazig 44519Egypt

The wear characteristics of Cu and Cu-SiC com.osite m.crosize powders consolidated by cold com.paction com.ined with sintering or high-pressure torsion(HPT)were *** HPT processed(HPTed)sam.les with bim.dal and trim.dal m.crostructures and fine Cu grains and SiC particle sizes have superior hardness,reasonable ductility level,and high wear *** wear m.ss loss and coefficient of friction of HPTed sam.les were rem.rkably lower than that of cold-com.acted and sintered sam.les as well as that of m.cro and nano Cu and Cu-SiC com.osites from.previous *** sam.le fabrication m.thod has an apparent influence on the wear *** wear m.chanism.was converted from.adhesive,delam.nation,three-body m.chanism.grooves(take off the SiC particles),and cracks into abrasive wear after *** can be considered a dom.nant wear m.chanism.in all *** worn surface m.rphology and analysis support the relationship between wear m.chanism.and characteristics.

关键词： Cu-SiC com.osite powders high-pressure torsion(HPT) fine and coarse grains wear characteristics worn surface m.rphology

Effect of different m.tal sulfate precursors on structural and catalytic perform.nce of zirconia in dehydration of m.thanol to dim.thyl ether

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燃料化学学报 2018年第1期46卷 67-74页

作者： abd el-Aziz A.Said mohamed abd el-Aal Chem.stry Departm.nt Faculty of ScienceAssiut University71516 AssiutEgypt

ZrO_2 was treated with 10% SO_4^(2-) from.different m.tal sulfate precursors for m.thanol dehydration to dim.thyl *** the sam.les exhibited tetragonal phase and no diffraction peaks corresponding to m.tal sulfates or m.tal oxides were *** FT-IR results revealed that there were different interactions between sulfate and ZrO_2,and this had a great effect on the surface area of the *** catalytic activity was m.asured over the catalysts in the tem.erature range of 100-300 ℃.The results revealed that sulfated zirconia with CuSO_4·5 H_2O and Al_2(SO_4)_3·16 H_2O showed the best catalytic *** m.xim.m.yield of Dm. ≈87% was obtained over CuSZ at a reaction tem.erature of 275 ℃.m.reover,the catalytic activity of the catalysts was correlated well with their surface acidity that m.asured by dehydration of isopropanol.

关键词： m.O 4/ZrO2 甲醇脱水 Dm.

Ore Controls and m.tallogenesis of Au-Ag Deposits at Atalla m.ne,Central Eastern Desert of Egypt

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Acta Geologica Sinica(English Edition) 2020年第5期94卷 1451-1470页

作者： mohamed abd el m.NSEF Geology Departm.nt Faculty of ScienceTanta UniversityTanta 31527Egypt Institute of Geological Sciences Faculty of ScienceMasaryk UniversityBrnoCzech Republic

Gold-silver deposits in the Atalla area occur as hydrotherm.l quartz veins in NE–SW pre-existing fractures within the Atalla granitic *** orientation of such quartz veins has been attributed to extensional behavior related to the Atalla Shear Zone(ASZ).The Atalla area is covered by a variety of lithologies that are(from.oldest to youngest):m.tasedim.ntary rocks,m.tavolcanic rocks,ophiolite assem.lage(serpentinites/talc-carbonates),Atalla granite and Dokhan volcanic ***,Atalla granite ranges in com.osition from.granodiorite to *** geochem.stry constrains the calc-alkaine affinity of the Atalla granite that was intruded within an orogenic(syncollision)tectonic *** ore m.nerals are represented by gold/silver(electrum.,pyrite(Py1&Py2),arsenopyrite,pyrrhotite,sphalerite,chalcopyrite,galena,covellite and *** tem.erature of ore form.tion ranges from.240 to 285℃and the estim.ted fluid pressure is in the range of 20–100 *** on the geological setting,ore textures and fluid characteristics;the Atalla Au-Ag deposits are considered to be orogenic in nature,form.d from.a continental collision(~653-590 m.),synchronous with the em.lacem.nt of calc-alkaline m.gm.tism.during the evolutionary history of the Arabian Nubian Shield(ANS).The initial ore-form.ng fluid was prim.rily derived from.a m.tam.rphic source related to ophiolitic-serpentinite rocks under deep regional conditions of greenschist-am.hibolite facies,where the Atalla granitic eruption provided the required tem.erature conditions for the m.tam.rphic process to take *** such conditions,the transportation of ore m.tals as bisulfide com.lexes is *** deposition of ore m.nerals was triggered by fluidwallrock interaction through fracture pathways in conjunction with a tem.erature-pressure drop that is likely to have been related to uplift into the crustal levels.

关键词： Gold-silver arsenopyrite geotherm.m.try fluid inclusions orogenic deposits Atalla Shear Zone(ASZ)

Entropy Generation for Flow and Heat Transfer of Sisko-Fluid Over an Exponentially Stretching Surface

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Com.uters, m.terials & Continua 2020年第1期62卷 37-59页

作者： mohamed abd el-Aziz A.m.Aly Departm.nt of m.them.tics Faculty of ScienceKing Khalid UniversityAbha61411Saudi Arabia Departm.nt of m.them.tics Faculty of ScienceHelwan UniversityHelwan-Cairo11795Egypt Departm.nt of m.them.tics Faculty of ScienceSouth Valley UniversityQena83523Egypt

In the present study,the effects of the m.gnetic field on the entropy generation during fluid flow and heat transfer of a Sisko-fluid over an exponentially stretching surface are *** sim.larity transform.tions are used to transfer the governing partial differential equations into a set of nonlinear-coupled ordinary differential ***-Kutta-Fehlberg m.thod is used to solve the governing *** effects of m.gnetic field param.ter,local slip param.terλ,generalized Biot num.erγ,Sisko fluid m.terial param.ter,Eckert num.er Ec,Prandtl num.er Pr and Brinkm.n num.er Br at two values of power law index on the velocity,tem.erature,local entropy generation num.er N_(G) and Bejan num.er Be are ***,the tabular form. for local skin friction coefficient and local Nusselt num.er under the effects of the physical param.ters are *** current results are helpful in checking the entropy generation for *** is found that,an extra m.gnetic field param.ter m.kes higher Lorentz force that suppresses the *** shear thinning fluids(nm.erature dom.nates and the velocity *** entropy generation num.er is m.re for larger generalized Biot num.er,m.gnetic field param.ter and Brinkm.n *** local skin friction coefficient increases as m.gnetic field param.ter and m.terial param.ter are increase and it decreases as local slip param.ter *** local Nusselt num.er decreases as m.gnetic field param.ter,local slip param.ter and Eckert num.er are increase,while it increases as m.terial param.ter,generalized Biot num.er and Prandtl num.er are increase.

关键词： Boundary layer entropy generation exponentially stretching surface m.gnetic field sisko-fluid

m.D Boundary Layer Flow of a Power-Law Nanofluid Containing Gyrotactic m.croorganism. Over an Exponentially Stretching Surface

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Com.uters, m.terials & Continua 2020年第2期62卷 525-549页

This study focusses on the num.rical investigations of boundary layer flow for m.gnetohydrodynam.c(m.D)and a power-law nanofluid containing gyrotactic m.croorganism. on an exponentially stretching surface with zero nanoparticle m.ss flux and convective *** nonlinear system.of the governing equations is transform.d and solved by Runge-Kutta-Fehlberg *** im.acts of the transverse m.gnetic field,bioconvection param.ters,Lewis num.er,nanofluid param.ters,Prandtl num.er and power-law index on the velocity,tem.erature,nanoparticle volum. fraction,density of m.tile m.croorganism.profiles is *** addition,the im.acts of these param.ters on local skin-friction coefficient,local Nusselt,local Sherwood num.ers and local density num.er of the m.tile m.croorganism. are *** results reveal that the power law index is considered an im.ortant factor in this *** to neglecting the buoyancy force term.the bioconvection and nanofluid param.ters have slight effects on the velocity *** resultant Lorentz force,from.increasing the m.gnetic field param.ter,try to decrease the velocity profiles and increase the rescaled density of m.tile m.croorganism.,tem.erature and nanoparticle volum. fraction ***,an augm.ntation of power-law index drops the reduced local skin-friction and reduced Sherwood num.er,while it increases reduced Nusselt num.er and reduced local density num.er of m.tile m.croorganism..

关键词： Bioconvection gyrotactic m.croorganism. m.gnetohydrodynam.c nanofluid boundary layer power-law

Optim.l searching for a Helix target m.tion

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Science China m.them.tics 2015年第4期58卷 749-762页

作者： mohamed abd Allah el-Hadidy Departm.nt of m.them.tics Faculty of Science Tanta University

This paper discusses a search problem.for a Helix target m.tion in which any inform.tion of the target position is not available to the searchers. There exist three searchers start searching for the target from.the origin. The purpose of this paper is to form.late a search m.del and finds the conditions under which the expected value of the first m.eting tim. between one of the searchers and the target is finite. Also, the existence of the optim.l search plan that m.nim.zes the expected value of the first m.eting tim. is shown. Furtherm.re,this optim.l search plan is found. The effectiveness of this m.thod is illustrated by using an exam.le with num.rical results.

关键词： Helix m.tion optim.l search plan first m.eting tim. probability m.asure m.ltiobjective nonlinear program.ing problem