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The effect of positive/negative ion on the dust grain charging process in a Vasyliunas-Cairns (VC)-distributed dusty plasma system

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Plasma Science and Technology 2019年第6期21卷 58-62页

作者： n ahmad A A ABID Y AL-HADEETHI M n S QURESHI Saqib REHMAn Department of Engineering and Applied Physics University of Science and Technology of China Hefei 230026 People's Republic of China CAS Key Laboratory of Geospace Environment Department of Geophysics and Planetary ScienceUniversity of Science and Technology of China Hefei 230026 People's Republic of China Department of Physics Faculty of Sciences King Abdulaziz Unniversity Jeddah 21589 Saudi Arabia Department of Physics GC University Lahore 54000 Pakistan Department of Chemical Physics University of Science and Technology of China Hefei 230026People's Republic of China

Charging mechanism of dust particles has been considered as a growing research area in dusty plasma physics because of its exciting *** this paper,we consider a low-temperature non-equilibrium multispecies plasma model,which consists of Vasyliunas-Caims (VC) distributed electrons,negative/positive streaming ions,and negatively-charged dust grains to explain the charging mechanism of dust *** main theme of this work is to derive expressions of currents for negatively-charged dust grains (considering an equilibrium state position) in the plasma environment comprised of electrons and positive/negative streaming ions using the VC distribution *** proposed model shows that the dust grain surface potential is significantly affected by different plasma parameters such as the negative ion streaming velocity (Sn),positive ion streaming velocity (Si),spectral indices of VC distribution,negative ion charging state (Zn),positive ion charging state (Zi),and negative ion number density (ρ).

关键词： dust grain surface potential vasyliunas-cairns power law velocity distribution function multi species plasma

AC measurements of spray-deposited CdS:In thin films

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Journal of Central South University 2012年第3期19卷 829-834页

作者： S.J.Ikhmayies R.n.ahmad-Bitar Department of Basic Sciences-Physics Faculty of Information TechnologyAl Isra University Physics Department Faculty of ScienceUniversity of Jordan

Indium doped cadmium sulfide thin films （CdS：In） were produced by the spray pyrolysis technique on glass substrates. AC measurements were used to investigate the electrical properties of the films depending on Brick-layer model for polycrystalline materials. The measurements were performed at room temperature in the dark and room light in the frequency range from 20 Hz to 1 MHz using coplanar indium electrodes. The data were analyzed by using Bode plots for the impedance Z and dielectric loss tang with frequencyf It is found that the impedance has no dependence on frequency in the low frequency region but has 1/f dependence in the high frequency region. One dielectric loss peak is obtained, which means the presence of a single relaxation time, and hence the films are modeled by just one RC circuit which represents the grains. This means that there is just one conduction mechanism that is responsible for the conduction in the bulk, due to electronic transport through the grains. Real values of the impedance in the low frequency region and relaxation times for treated and as-deposited fihns were estimated.

关键词： II-VI compounds spray pyrolysis impedance dielectric loss Bode plots

Using HF rather than nH_4F as doping source for spray-deposited SnO_2:F thin films

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Journal of Central South University 2012年第3期19卷 791-796页

作者： S.J.Ikhmayies R.n.ahmad-Bitar Department of Basic Sciences-Physics Faculty of Information TechnologyAl Isra University Physics Department Faculty of ScienceUniversity of Jordan

Fluorine doped tin oxide SnO2：F thin films were prepared by the spray pyrolysis （SP） technique on glass substrates by using SnC12.2H2O as a precursor and nH4F and HF as doping compounds. A comparison between the properties of the films obtained by using the two doping compounds was performed by using I-V characteristics in the dark at room temperature, AC measurements, and transmittance. It is found that the films prepared by using HF have smaller resistivity, lower impedance and they are less capacitive than films prepared by using nH4F. In addition, these films have higher transmittance, higher optical bandgap energy and narrower Urbach tail width. These results are interesting for the use of SnO2：F as forecontact in CdS/CdTe solar cells.

关键词： CdS/CdTe solar cells transparent conducting oxides spray pyrolysis doping

A comparison between different ohmic contacts for ZnO thin films

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Journal of Semiconductors 2015年第3期36卷 41-45页

作者： Shadia J.Ikhmayies naseem M.Abu El-Haija Riyad n.ahmad-Bitar AlIsra University Faculty of Information Technology Department of Basic Sciences-Physics Physics Department Faculty of Science University of Jordan

There are several metals that form ohmic contacts for ZnO thin films, such as copper, aluminum and silver. The aim of this work is to make a comparison between these ohmic contacts. To achieve this purpose, polycrystalline ZnO thin films were prepared by the spray pyrolysis technique, and characterized by the I-V measurements at room temperature. Two strips of each metal were thermally evaporated on the surface of the film and measurements were first recorded in the dark and room light, then in the dark before and after annealing for A1, which was found to be the best in the set. Films with aluminum contacts gave the smallest resistivity, best ohmicity and they are slightly affected by light as required. On the other hand, copper was found to be the worst, and films with copper contacts gave the largest resistivity, worst ohmicity and they are the most affected by light. Annealing improved the aluminum contacts due to alloying and doping.

关键词： transparent conducting oxide ohmic contacts annealing solar cells

Optical transmission in thin films of vanadium compounds

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Journal of Semiconductors 2014年第7期35卷 10-14页

作者： Kh.S.Karimov M.Mahroof-Tahir M.Saleem n.ahmad A.Rashid GIK Institute of Engineering Sciences and Technology TopiDistrict SwabiKPK 23640Pakistan Physical Technical Institute of Academy of Sciences Rudaki Ave33Dushanbe 734025Tajikistan Saint Cloud State University 720 Fourth Avenue SouthSaint CloudMN 56301-4498USA Government College of Science Wahdat RoadLahore 54570Pakistan

Thin films of five vanadium compounds/composite：（1） VO2（3-fl）（3-fl = 3-Hydroxyflavone）, （2） VO（pbd）：（pbd = 1-Phenyl-l, 3-butadione）, （3） VO（dbm）2 （dbm = Dibenzoylmethane）, （4） VPc （Vanadyl Phthalocyanine） and （5） V2O5-PEPC （V2O5- poly-n-epoxypropylcarbazole composite）, were deposited by the dropcasting method from the solution in benzene. The transmittance-irradiance relationships were investigated and the transmission in the visible spectrum and optical images were obtained as well. It was found that the transmittance of the VO2（3-fl）, VO（pbd）2, VO（dbm）2 and VPc, was practically independent of the irradiance; whereas the transmittance of V2O5-PEPC decreased by 4% for thin and 9% for thick films with an increase of the irradiance.

关键词： vanadium compound/composite semiconductor thin film transmittance irradiance

First United Arab Emirates consensus on diagnosis and management of inflammatory bowel diseases:A 2020 Delphi consensus

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World Journal of Gastroenterology 2020年第43期26卷 6710-6769页

作者： Maryam Alkhatry ahmad Al-Rifai Vito Annese Filippos Georgopoulos ahmad n Jazzar Ahmed M Khassouan Zaher Koutoubi Rahul nathwani Mazen S Taha Jimmy K Limdi Gastroenterology and Endoscopy Department Ibrahim Bin Hamad Obaid Allah HospitalMinistry of Health and PreventionRas Al KhaimanUnited Arab Emirates Department of Gastroenterology Sheikh Shakbout Medical CityAbu DhabiUnited Arab Emirates Department of Gastroenterology Valiant ClinicDubaiUnited Arab Emirates Department of Gastroenterology and Endoscopy American HospitalDubaiUnited Arab Emirates Gastroenterology and Endoscopy Unit Al Zahra HospitalDubaiUnited Arab Emirates Gastroenterology Division Sheikh Khalifa Medical CityAbu DhabiUnited Arab Emirates Digestive Disease Unit Rashid HospitalDubaiUnited Arab Emirates Digestive Disease Institute Cleveland ClinicAbu DhabiUnited Arab Emirates Department of Gastroenterology Mediclinic City HospitalDubaiUnited Arab Emirates Gastroenterology and Hepatology Tawam HospitalAl AinUnited Arab Emirates Department of Gastroenterology The Pennine Acute Hospitals NHS TrustManchester Academic Health SciencesUniversity of ManchesterManchester M85RBUnited Kingdom

Ulcerative colitis and Crohn’s disease are the main entities of inflammatory bowel disease characterized by chronic remittent inflammation of the gastrointestinal *** incidence and prevalence are on the rise worldwide,and the heterogeneity between patients and within individuals over time is *** progressive advance in our understanding of the etiopathogenesis coupled with an unprecedented increase in therapeutic options have changed the management towards evidence-based interventions by clinicians with *** guideline was stimulated and supported by the Emirates Gastroenterology and Hepatology Society following a systematic review and a Delphi consensus process that provided evidence-and expert opinion-based *** up-to-date guidance is provided regarding diagnosis,evaluation of disease severity,appropriate and timely use of different investigations,choice of appropriate therapy for induction and remission phase according to disease severity,and management of main complications.

关键词： Ulcerative colitis Crohn’s disease Infliximab Adalimumab Vedolizumab Ustekinumab Tofacitinib

Rotating effects on the thermophysical properties of a two-dimensional GaAs quantum ring

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Communications in Theoretical Physics 2024年第6期76卷 165-173页

作者： ahmad Ghanbari Department of Physics College of ScienceYasouj UniversityYasoujIran

In this work,we have investigated the rotating effect on the thermodynamic properties of a 2D quantum ***,we have considered the radial potential of a 2D quantum ring and solved the Schrödinger equation in the presence of the Aharonov-Bohm effect and a uniform magnetic field for the considered *** to the solution of the equation,we calculated the eigenvalues and eigenfunctions of the considered *** the calculated energy spectrum,we obtained the partition function and thermodynamic properties of the system,such as the mean energy,specific heat,entropy and free *** results show that the rotating effect has a significant influence on the thermophysical properties of a 2D quantum *** also study other effects of the rotating term:(1)the effect of different values of rotating parameters,and(2)the effect of negative rotation on the thermodynamic properties of the *** results are discussed in detail.

关键词： Schrodinger equation quantum ring rotation effect thermophysical properties

Finite element model updating for structural damage detection using transmissibility data

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 87-101页

作者： ahmad Izadi Akbar Esfandiari Department of Maritime Engineering Amirkabir University of TechnologyTehran 15875-4413Iran

This paper presents a new finite element model updating method for estimating structural parameters and detecting structural damage location and severity based on the structural responses(output-only data).The method uses the sensitivity relation of transmissibility data through a least-squares algorithm and appropriate normalization of the extracted *** proposed transmissibility-based sensitivity equation produces a more significant number of equations than the sensitivity equations based on the frequency response function(FRF),which can estimate the structural parameters with higher *** abilities of the proposed method are assessed by using numerical data of a two-story two-bay frame model and a plate structure *** evaluating different damage cases,the number,location,and stiffness reduction of the damaged elements and the severity of the simulated damage have been accurately *** reliability and stability of the presented method against measurement and modeling errors are examined using error-contaminated *** parameter estimation results prove the method’s capabilities as an accurate model updating algorithm.

关键词： damage detection model updating output-only transmissibility sensitivity equation

Correlation between structural phase transition and physical properties of Co^(2+)/Gd^(3+)co-substituted copper ferrite

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Journal of Rare Earths 2024年第7期42卷 1344-1353,I0006页

作者： Mohsen Choupani ahmad Gholizadeh School of Physics Damghan UniversityDamghan36716-45667Iran

The doping of the spinel ferrites with selective cations usually improves the properties of the parent *** effect of Co^(2+)/Gd^(3+)co-substitution on the microstructure,optical,and magnetic properties of Cu1-xCoxFe2-xGdxO4 prepared by the citrate-nitrate auto-combustion synthesis was *** of the samples was performed with powder X-ray diffraction(XRD),Raman and Fouriertransform infrared(FTIR)spectroscopy,field-emission scanning electron microscopy,X-ray energydispersive spectroscopy,UV-Vis spectroscopy,and a vibrating sample *** results of XRD,Raman,and FTIR analysis show a gradual structural phase transition from a tetragonal(I41/amd)structure to a cubic(Fd3m)*** bandgap energy of the studied samples is in a range of 1.57-1.75 eV with a minimum in sample x=0.06 and then *** investigations show that the presence of Co^(2+)/Gd^(3+)cations in an octahedral site of the copper ferrite structure could increase saturation magnetization and coercive field from 567.9 Oe and 23.62 emu/g to 929.4 Oe and 28.27 emu/g,respectively.

关键词： Spinel copper ferrite Citrate-nitrate method Structure phase transition Microstructure properties Magnetic properties Rare earths