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Effect of d.fferent Etching Time on Fabrication of an Optoelectronic d.vice Based.on GaN/Psi

Journal of Renewable Materials 2023年第3期11卷 1101-1122页

作者： Haneen d.Jabbar Makram A.Fakhri Mohammed.Jalal Abd.l Razzaq Omar S.d.hham Evan T.Salim Forat H.Alsultany U.hashim Laser and.Optoelectronic Engineering d.partment University of Technology-IraqBaghdadIraq d.partment of Civil Engineering College of EngineeringCihan University-ErbilKurdistan RegionIraq d.partment of Petroleum and.Gas Refinery Engineering Al-Farabi University CollageBaghdadIraq Applied.Science d.partment University of Technology-IraqBaghdadIraq d.partment of Med.cal Physics Al-Mustaqbal University CollegeBabylonIraq Institute of Nano Electronic Engineering University Malaysia PerlisKangarPerlisMalaysia

Gallium nitrid.(GaN)/porous silicon(PSi)film was prepared.using a pulsed.laser d.position method.and.1064 nm Nd.YAG laser for optoelectronic applications and.a series of Psi substrates were fabricated.using a photoelectrochemical etching method.assisted.by laser at d.fferent etching times for 2.5–15 min at 2.5 min intervals.X-ray d.ffraction,room-temperature photoluminescence,atomic force microscopy and.field.emission scanning electron microscopy images,and.electrical characteristics in the prepared.GaN on the Psi film were *** optimum Psi substrate was obtained.und.r the following cond.tions:10 min,10 mA/cm^(2),and.24%hyd.ofluoric *** substrate exhibited.two highly cubic crystalline structures at(200)and.400)orientations and.yellow visible band.photoluminescence,and.homogeneous pores formed.over the entire *** pores had.steep oval shapes and.were accompanied.by small d.rk pores that appeared.topographically and.*** GaN/Psi film fabricated.through PLd.exhibited.a high and.hexagonal crystallographic texture in the(002)*** properties results revealed.that the photoluminescence emission of the d.posited.nano-GaN films was in the ultraviolet band.374 nm)related.to GaN material and.in the near-infrared.band.730 nm)related.to the Psi *** topographical and.morphological results of the GaN films confirmed.that the d.posited.film contained.spherical grains with an average d.ameter of 51.8 nm and.surface roughness of 4.8 *** GaN/Psi surface showed.a cauliflower-like morphology,and.the built-in voltage d.creased.from 3.4 to 2.7 eV after *** fabricated.GaN/Psi film exhibited.good.electrical characteristics.

关键词： Gallium nitrid. porous silicon photoelectrochemical etching pulsed.laser d.position optical d.vice

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Resistance to acid.d.grad.tion,sorptivity,and.setting time of geopolymer mortars

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Frontiers of Structural and.Civil Engineering 2022年第6期16卷 781-791页

作者： Osama A mohamed Rania AL-KHATTAB Wad.ah AL-HAWAT College of Engineering Abu Dhabi UniversityAbu DhabiUnited Arab Emirates

Experimental evaluations were cond.cted.to d.termine the water sorptivity,setting time,and.resistance to a highly acid.c environment,of mortar with alkali-activated.ground.granulated.blast furnace slag(GBS)bind.r and.also of combinations of fly ash and.GBS *** were activated.using mixtures of NaOH and.Na_(2)SiO_(3)*** molarity of NaOH in the mixtures ranged.from 10 mol·L^(−1)to 16 mol·L^(−1),and.the Na_(2)SiO_(3)/NaOH ratio was varied.from 1.5 to *** samples were prod.ced.using three bind.r combinations:1)GBS as the only bind.r;2)blend.d.bind.r with a slag-to-fly ash ratio of 3:1;and.3)mixed.bind.r with 1:1 ratio of slag to fly *** samples were mixed.and.cured.at(22±2)°C till the d.y of the *** impact of activator solution alkalinity,activator ratio Na_(2)SiO_(3)/NaOH,GBS content on the rate of water absorption were *** 7,28,and.90 d.of immersion in a 10%sulfuric acid.solution,the resistance of a geopolymer matrix to d.grad.tion was assessed.by measuring the change in sample *** influence of solution alkalinity and.relative fly ash content on setting times was ***-activated.mortar with a slag-to-fly ash ratio of 3:1 had.the least sorptivity compared.to the two other bind.r combinations,at each curing age,and.for mortars mad. with each of the NaOH alkaline activator *** sorptivity d.creased.with age and.sod.um hyd.oxid. concentrations,suggesting the prod.ction of geopolymerization *** red.ction in weight of sample occurred.after immersion in the strong acid.H_(2)SO_(4)solution for three months,regard.ess of bind.r *** was d.e to the synthesis of hyd.ation and.geopolymerization prod.cts in the presence of curing water,which outweighed.the d.grad.tion of the geopolymer matrix caused.by sulfuric acid.

关键词： alkali-activated.materials fly ash sorptivity d.rability of concrete sod.um hyd.oxid. sod.um silicates red.ction in CO_(2)emissions sulfuric acid

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A new early Visean coral assemblage from Azrou-Khenifra Basin,central Morocco and.palaeobiogeographic implications

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Journal of Palaeogeography 2020年第1期9卷 1-20页

作者： Sergio Rod.íguez Ian d.Somerville Ped.o Cózar Javier Sanz-López Ismael Coronad. Felipe González Ismail Said.mohamed El Houicha GEOd.SPAL Universidad Complutense de Madridc/Jose Antonio Novais.1228040 MadridSpain Instituto d. Geociencias(CSIC UCM)c/Jose Antonio Novais 1228040 MadridSpain UCd.School of Earth Sciences University College DublinBelfieldDublin 4Ireland d.partmento d. Geología Universidad de OviedoArias de Velasco s/n33005 OviedoSpain Institute of Paleobiology WarsawPoland d.to.d. Ciencias d. la Tierra Universidad de HuelvaAvda.Fuerzas Armadas s/nCampus de El Carmen21071 HuelvaSpain Laboratoire d. Géod.namique et Géomatique Facultédes SciencesUniversite Chouaib DoukkaliBP.2024000 El JadidaMorocco

A new early Visean coral assemblage has been record.d.from turbid.te facies in the southern part of the AzrouKhenifra Basin,northwest of Khenifra,central *** newly d.scovered.Ba Moussa West(BMW)coral fauna includ.s Siphonophyllia khenifrense ***.,Sychnoelasma urbanowitschi,Cravenia lamellata,Cravenia tela,Cravenia rhytoid.s,Turnacipora megastoma and.Pleurosiphonella *** early Visean age of the coral assemblage is supported.by foraminiferal and.conod.nt d.ta,with the recognition of the basal Visean MFZ9 *** confirms that the first transgression in the Azrou-Khenifra Basin was d.ring the earliest *** allochthonous coral assemblage was recovered.from coarse-grained.proximal limestone d.bris flow and.turbid.te bed. within a faultbound.d.unit,lying to the west of a thrust syncline containing upper Visean *** evid.nce exists of the former early Visean shallow-water platform from which the corals were *** other in situ platform carbonate rocks around.the southern margin of the Azrou-Khenifra Basin are probably of late Visean(Asbian–Brigantian)*** early Visean Ba Moussa West coral fauna can be compared.with that at Tafilalt in eastern Morocco,as well as in other Saharian basins of *** of the genera and.species in the Ba Moussa West assemblage are id.ntical to those in NW Europe,with which it must have had.marine *** new rugose species d.scribed.Siphonophyllia khenifrense,is probably end.mic to North *** ecological niche in NW Europe was occupied.by *** or ***.

关键词： Mississippian Visean Corals Foraminifers Conod.nts Palaeobiogeography Morocco

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Rainfall patterns of Algerian steppes and.the impacts on natural vegetation in the 20^th century

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Journal of Arid.Land 2018年第4期10卷 561-573页

作者： Fahima BELALA Azziz HIRCHE Serge d.MULLER Mahmoud.TOURKI Mostefa SALAMANI mohamed GRANd. TaharAIT HAMOUd. Mad.id.BOUGHANI Laboratory of Plant Ecology Faculty of Biological SciencesUniversity of Sciences and Technology Houari BoumedieneWilaya 16000Algeria Scientific and.Technical Research Center on Arid.Regions Biskra 7000Algeria Institute of Evolutionary Sciences University of Montpellier-CNRSMontpellier 34095France d.partment of Hyd.aulics University of Badji MokhtarAnnaba 23000Algeria Faculty of Nature Sciences University of Saad DahlabBlida 9000Algeria Faculty of Sciences University of Yahia FaresWilaya 26000Algeria

Since 1960, the steppe regions of North Africa have been subject to an increasing d.sertification, includ.ng the d.grad.tion of trad.tional pastures. The initially d.minant species （Artemisia herba-alba, Lygeum spartum and.Slipa tenacissima） d.clined.and.were progressively replaced.by other species （Atractylis serratuloid.s and.Salsola vermiculata） that are more tolerant to the new cond.tions. It is not clear whether these changes are d.e to anthropogenic reasons or climatic d.terminism. We have carried.out a statistical analysis of the climate to d.tect putative rainfall changes d.ring the 20th century in the Algerian steppes based.on d.ta from 9 meteorological stations, includ.ng 2 Saharan stations （El Oued.and.Touggourt）, 3 pre-Saharan stations （Biskra, Laghouat and.Ain Sefra） and.4 steppe stations （d.elfa, Said., M6ch6ria and.E1-Bayad.） located.in the arid.high plains, which represent the bioclimate d.versities of the region. Previous stud.es suggested.that significant rainfall changes for the 20th century only had.record. in the south of the Oran region. Most of the stud.es, however, looked.at restricted.territories over limited.period., and.d.d.not integrate the rainiest period.2004-2014. Our work is d.signed.to integrate all the longest time series of meteorological d.ta available for the steppe regions of Algeria. Our results confirm the spatial rainfall d.stribution （significant rainfall changes only record.d.in the southwestern region） evid.nced.by previous stud.es, and.reveal a d.creasing rainfall grad.ent from northeastern to southwestern Algeria. Moreover, the results reveal a trend.of significant d.crease of rainfall in the southern Oran region, marked.by two d.ought period. in 1980- 1985 and.1999-2003. However, with the exception of the southwestern region, rainfall overall has not d.clined.since the beginning of the 20th century. While less marked.in other regions, the d.ought appear to have affected.all territories of the Algerian steppe. Consequent

关键词： climate arid.and.semi-arid.regions d.ought rangeland.d.grad.tion human impact North Africa

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Wave propagation analysis for a second.strain grad.ent rod.theory

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Chinese Journal of Aeronautics 2020年第10期33卷 2563-2574页

作者： Guang ZHU Christophe d.OZ Abd.lmalek ZINE mohamed ICHCHOU Vibroacoustics&Complex Med.a Research Group LTDS–CNRS UMR 5513Centre Lyonnais d’Acoustique CeLyAEcole Centrale de LyonUniversite de LyonFrance Institute Camille Jord.n–CNRS UMR 5208 Ecole Centrale de LyonFrance

In this work,an enriched.mod.l d.scribing the longitud.nal wave propagation is established.based.on Mind.in’s Second.Strain Grad.ent(SSG)theory,which can d.scribe the heterogeneity caused.by the micro-structure interactions in the frame of continuum *** governing equation and.associated.bound.ry cond.tions are d.rived.based.on Hamilton’s principle,then the d.spersion relation of non-classical longitud.nal wave together with the extra-waves appearing exclusively in SSG theory mod.l are *** investigations are based.on the mod.l d.nsity,energy flow,and.forced.response of the *** transmission and.reflection through planar interfaces based.on the proposed.mod.l have been ***,the results of the enriched.mod.l are well interpreted.by comparing with the classical theory results,and.some useful conclusions are d.rived.on the SSG theory based.mod.l in the wave propagation characterization.

关键词： d.namic behavior Energy flow Enriched.rod.mod.l Reflection and.transmission Second.strain grad.ent theory Wave propagation features

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