检索结果-南通市图书馆

Structural, M?ssbauer spectroscopy, magnetic properties, and thermal measurements of Y(3-x)Dy_x Fe_5O_(12)

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第10期27卷 558-564页

作者： Mahdi Lataifeh Qassem I Mohaidat sami h mahmood Ibrahim Bsoul Mufeed Awawdeh Ibrahim Abu-Aljarayesh Mu'ath Altheeba Physics Department Yarmouk University Irbid 21163 Jordan Physics Department The University of Jordan Amman 11942 Jordan Physics Department AI al-Bayt University Mafraq 13040 Jordan

Yttrium iron garnet powder samples（Y3-xDyxFe5O12）, where part of yttrium ions are substituted by dysprosium ions with different concentrations are prepared by the solid state reaction method. The properties of the prepared samples are examined by different methods such as x-ray diffraction（XRD）, Mssbauer spectroscopy, macroscopic magnetization measurements, and thermal measurements. The XRD measurements show that all the samples reveal the presence of a single garnet phase with a BCC structure. Room temperature Mssbauer spectra indicate that iron ions occupy three magnetic sites, i.e., two octahedral sites and one tetrahedral site. The saturation magnetization and the initial magnetic susceptibility decrease with the increase of Dy^3＋ substitution. The Curie temperature obtained from the thermal measurements seems to be independent of Dy^3＋ substitution.

关键词： Mossbauer spectroscopy magnetic properties x-ray diffraction differential scanning calorimetry

Magnetic Properties and hyperfine Interactions in M-Type BaFe_(12-2x)Mo_(x)Zn_(x)O_(19) hexaferrites

在线全文

学校读者我要写书评

暂无评论

Journal of Applied Mathematics and Physics 2014年第5期2卷 77-87页

作者： sami h.mahmood Ghada h.Dushaq Ibrahim Bsoul Mufeed Awawdeh hassan K.Juwhari Bashar I.Lahlouh Murad A.AlDamen Physics Department The University of JordanAmmanJordan Physics Department Al al-Bayt UniversityMafraqJordan Physics department Yarmouk UniversityIrbidJordan Chemistry Department The University of JordanAmmanJordan

A series of M-Type barium hexaferrites with the general composition BaFe12-2xMoxZnxO19 were synthesized at 1100°C by a simple wet chemical mixture route. The properties of the prepared samples were examined by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, and Mössbauer spectroscopy. The diffraction patterns for all samples were found to agree well with the standard pattern of BaFe12O19 hexaferrite with no extraneous diffraction peaks. The products formed as well crystallized hexagonal platelet-like particles while the EDS measurements revealed the stoichiometric cationic ratios of the prepared samples. The spectral variations elucidated by Mössbauer spectroscopy were utilized to determine the different cation preferential site occupations as a function of x. Finally, the saturation magnetizations, magnetic anisotropies, and the anisotropy fields, determined from the magnetic measurements, showed consistency with the relative subspectral Mössbauer intensities and the single ion model for the anisotropy constant.

关键词： Mossbauer Spectroscopy Magnetic Properties hysteresis Crystal Field Sintering Magnetic Materials

Ab-initio calculations of bandgap tuning of In1-xGaxY(Y=N,P)alloys for optoelectronic applications

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第11期30卷 467-474页

作者： Muhammad Rashid Jamil M mahmood Q Shahid M Ramay Asif mahmood A Ghaithan h M Department of Physics Ghazi University City CampusDera Ghazi Khan32200Pakistan Department of Physics COMSATS University IslamabadIslamabad 44000Pakistan Basic and Applied Scientific Research Center(BASRC) College of Science of DammamImam Abdulrahman Bin Faisal UniversityP.O.Box 383Dammam 31113Saudi Arabia Department Physics College of ScienceImam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam 31441Saudi Arabia Physics and Astronomy Department College of ScienceKing Saud UniversityRiyadhSaudi Arabia Chemical Engineering Department College of EngineeringKing Saud UniversityRiyadhSaudi Arabia

The III–V alloys and doping to tune the bandgap for solar cells and other optoelectronic devices has remained a hot topic of research for the last few *** the present article,the bandgap tuning and its influence on optical properties of In1-xGaxN/P,where(x=0.0,0.25,0.50,0.75,and 1.0)alloys are comprehensively analyzed by density functional theory based on full-potential linearized augmented plane wave method(FP-LAPW)and modified Becke and Johnson potentials(TB-mBJ).The direct bandgaps turn from 0.7 eV to 3.44 eV,and 1.41 eV to 2.32 eV for In1-xGaxN/P alloys,which increases their potentials for optoelectronic *** optical properties are discussed such as dielectric constants,refraction,absorption,optical conductivity,and *** light is polarized in the low energy region with minimum *** absorption and optical conduction are maxima in the visible region,and they are shifted into the ultraviolet region by Ga ***,static dielectric constant e1(0)is in line with the bandgap from Penn’s model.

关键词： density functional theory direct bandgap III-V semiconductors tuning of optical band gap solar cell applications

Large-amplitude dust acoustic solitons in an opposite polarity dusty plasma with generalized polarization force

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第1期31卷 199-207页

作者： mahmood A.h.Khaled Mohamed A.Shukri Yusra A.A.hager Department of Physics Faculty of Education(Al-Mahweet)Sana'a UniversitySana'aYemen Department of Physics Faculty of ScienceSana'a UniversitySana'aYemen Department of Physics Faculty of EducationSana'a UniversitySana'aYemen

Linear and nonlinear dust acoustic(DA)waves have been investigated in an opposite polarity dusty plasma comprising negatively and positively charged dust grains,Maxwellian electrons and ions,including the generalized polarization force *** properties of linear DA waves have been significantly altered by the dual dust polarity and polarization *** amplitude DA solitons have been discussed in the framework of the Sagdeev potential *** results show that both rarefactive and compressive solitons can exist in such a dusty *** basic features of the Sagdeev potential have been examined under the effect of the polarization force parameter R,the ratio of the charge number of the positive dust to that of the negative dust Z,and the Mach number *** results show that these parameters play a significant role in determining the region of existence of large amplitude DA solitons.

关键词： large amplitude opposite polarity dusty plasma polarization force

Quintessence anisotropic stellar models in quadratic and Born-Infeld modified teleparallel Rastall gravity

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第3期33卷 179-189页

作者： Allah Ditta 夏铁成 Irfan mahmood Asif mahmood Department of Mathematics Shanghai University and Newtouch Center for Mathematics of Shanghai UniversityShanghai 200444China Centre for high Energy Physics University of the PunjabLahorePakistan College of Engineering Chemical Engineering DepartmentKing Saud University RiyadhSaudi Arabia

This study aims to discuss anisotropic solutions that are spherically symmetric in the quintessence field,which describe compact stellar objects in the modified Rastall teleparallel theory of *** achieve this goal,the Krori and Barua arrangement for spherically symmetric components of the line element is *** explore the field equations by selecting appropriate off-diagonal tetrad ***-Infeld function of torsion f(T)=β√λT+1-1 and power law form h(T)=δTn are *** Born-Infeld gravity was the first modified teleparallel gravity to discuss *** use the linear equation of state pr=ξρto separate the quintessence *** obtaining the field equations,we investigate different physical parameters that demonstrate the stability and physical acceptability of the stellar *** use observational data,such as the mass and radius of the compact star candidates PSRJ 1416-2230,Cen X-3,&4U 1820-30,to ensure the physical plausibility of our findings.

关键词： anisotropic spheres quintessence field modified Rastall teleparallel gravity equation of state(EoS) f(T)gravity

Low Frequency Electromagnetic Instability in Unmagnetized Inhomogeneous Dusty Plasmas

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2001年第3期18卷 402-404页

作者： S.mahmood Q.haque h.Saleem NPD PINSTECh P.O.NiloreIslamabadPakistan

The low frequency electromagnetic wave instability in an unmagetized inhomogeneous dusty plasma has been pointed *** has been noticed that there exists a stable mode if the propagation of the wave vector along the density gradient is ***,the mode becomes unstable by including the propagation of the wave in the opposite direction of the density gradient.

关键词： wave inhomogeneous opposite

Control strategy of shortcut nitrification

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2006年第1期18卷 58-61页

作者： QAISAR mahmood Department of Environmental Engineering Zhejiang University Hangzhou 310029 China.

Shortcut nitrification for ammonium-rich wastewater is energy-saving and cost-effective procedure that has become one of the hotspots in the field of biological denitrogenation. An orthogonal experiment was performed to study the combined effects of operational parameters on the performance of internal-loop airlift bioreactor for shortcut nitrification. The optimum operational parameters for the shortcut nitrification were fotmd as temperature 35 ℃, ph 8.0, dissolved oxygen concentration 1.0 mg/L, ammonium concentration 4 mmol/L and hRT 16 h, which have different influence on the performance of shortcut nitrification reactor. The ph, temperature and dissolved oxygen concentration have significant bearing on the process. The results showed that the shortcut nitrification reactor could be successfully started up within 42 d, and the reactor performance is steady with minimum NO2-/NOx- of 85.2%, maximum 93.4% and average value of 91.4% in effluent. Based on the analysis of experimental data, a new control strategy named “priority ＋ combination” for shortcut nitrification was suggested. Through this strategy, the startup and operation of shortcut nitrification for ammonium-rich sludge digester liquids were optimized. The control strategy works well to keep the reactor operation in steady state and in achieving high-efficiency for shortcut nitrification.

关键词： internal-loop airlift bioreactor shortcut nitrification orthogonal experiment control strategy sludge digester liquids

Activated sludge-mediated biodegradation of dimethyl phthalate under fermentative conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2008年第8期20卷 922-926页

作者： mahmood Qaisar Department of Botany Federal Government Post Graduate College Sector H-8 IslamabadPakistan

The biodegradation of dimethyl phthalate(DMP)was investigated under fermentative conditions in this *** nature of the intermediate compounds and the extent of mineralization were probed using high-pressure liquid chromatography(hPLC)and liquid chromatography-mass spectrometry(LC-MS)*** fermentative bacteria were able to biodegrade the DMP under anaerobic conditions,with the biodegradation rate of 0.36 mg DMP/(L·h).The results demonstrated that the DMP degradation under fermentative conditions ...

关键词： activated sludge biodegradation dimethyl phthalate fermentation phthalic acid mineralization

Effects of loading rate and hydraulic residence time on anoxic sulfide biooxidation

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第7期8卷 1149-1156页

作者： mahmood Qaisar ISLAM Ejazul Department of Environmental Engineering Zhejiang University

The optimal operation conditions in an anoxic sulfide oxidizing (ASO) bioreactor were investigated. The maximal removal rates for sulfide and nitrate were found to be 4.18 kg/(m3·d) and 1.73 kg/(m3·d), respectively. The volumetrical volumetric loading rates (LRs) observed through decreasing hydraulic retention time (hRT) at fixed substrate concentration are higher than those by increasing substrate concentration at fixed hRT. The sulfide oxidation in ASO reactor was partially producing both sulfate and sulfur; but the amount of sulfate produced was approximately one third that of sulfur. The process was able to tolerate high sulfide concentration, as the sulfide removal percentage always remained near 99% when influent concentration was up to 580 mg/L. It tolerated relatively lower nitrate concentration because the removal percentage dropped to 85% when influent con- centration was increased above 110 mg/L. The process can tolerate shorter hRT but careful operation is needed. Nitrate conversion was more sensitive to hRT than sulfide conversion since the process performance deteriorated abruptly when hRT was decreased from 3.12 h to 2.88 h. In order to avoid nitrite accumulation in the reactor, the influent sulfide and nitrate concentrations should be kept at 280 mg/L and 67.5 mg/L respectively. Present biotechnology is useful for removing sulfides from sewers and crude oil.

关键词： Anaerobic processes Anoxic nitrate removal Biodesulfurization Biotransformation Fluidized bed bioreactors hydraulic residence time (hRT)