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The Kadomtsev-Petviashvili equation for dust ion-acoustic solitons in pair-ion plasmas

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Chinese Physics B 2013年第3期22卷 366-371页

作者： Hafeez Ur-rehman Theoretical Plasma Physics Division PINSTECHP.O.NiloreIslamabadPakistan Department of Physics and Applied Mathematics PIEASP.O.NiloreIslamabadPakistan

Using the reductive perturbation method,we have derived the Kadomtsev-Petviashvili（KP） equation to study the nonlinear properties of electrostatic collisionless dust ion-acoustic solitons in pair-ion（p-i） *** have chosen the fluid model for the positive ions,the negative ions,and a fraction of static charged（both positively and negatively） dust *** solutions of these dust ion-acoustic solitons are plotted and their characteristics are *** is found that only the amplitudes of the electrostatic dust ion-acoustic solitons vary when the dust is introduced in the pair-ion *** is also noticed that the amplitude and the width of these solitons both vary when the thermal energy of the positive or negative ions is *** is shown that potential hump structures are formed when the temperature of the negative ions is higher than that of the positive ions,and potential dip structures are observed when the temperature of the positive ions supersedes that of the negative *** the pair-ion plasma mimics the electron-positron plasma,thus our results might be helpful in understanding the nonlinear dust ion acoustic solitary waves in super dense astronomical bodies.

关键词： charged and static dust particles pair-ion plasma soliton

Isolation of Cr(Ⅵ) reducing bacteria from industrial effuents and their potential use in bioremediation of chromium containing wastewater

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Journal of Environmental Sciences 2009年第6期21卷 814-820页

作者： Ahmed Zahoor Abdul rehman Department of Microbiology and Molecular Genetics University of the PunjabNew Campus

The present study was aimed to assess the ability of Bacillus ***-2-1 and Staphylococcus capitis to reduce hexavalent chromium into its trivalent *** ***-2-1 could tolerate Cr（Ⅵ）（4800 μg/mL） and *** could tolerate Cr（Ⅵ）（2800 μg/mL）.Both organisms were able to resist Cd^2＋（50 μg/mL）,Cu^2＋（200 μg/mL）,Pb^2＋（800 μg/mL）,Hg^2＋（50 μg/mL） and Ni2＋（4000 μg/mL）.*** resisted Zn^2＋ at 700 μg/mL while Bacillus ***-2-1 only showed resistance up to 50 μg/*** ***-2-1 and *** showed optimum growth at pH 6 and 7,respectively,while both bacteria showed optimum growth at 37°*** ***-2-1 and *** could reduce 85% and 81% of hexavalent chromium from the medium after 96 h and were also capable of reducing hexavalent chromium 86% and 89%,respectively,from the industrial effuents after 144 *** free extracts of Bacillus ***-2-1 and *** showed reduction of 83% and 70% at concentration of 10 μg Cr（Ⅵ）/mL,*** presence of an induced protein having molecular weight around 25 kDa in the presence of chromium points out a possible role of this protein in chromium *** bacterial isolates can be exploited for the bioremediation of hexavalent chromium containing wastes,since they seem to have a potential to reduce the toxic hexavalent form to its nontoxic trivalent form.

关键词： Cr(Ⅵ) reducing bacteria bioremediation Bacillus sp. JDM-2-1 Staphylococcus capitis

Numerical Investigation and Non-Axisymmetric Endwall Profiling of a Turbine Stage

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Journal of Thermal Science 2019年第4期28卷 811-825页

作者： rehman Abdul LIU Bo School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China Shaanxi Key Laboratory of Internal Aerodynamics in Aero-Engine Xi’an 710072China

This paper presents an optimization of a high pressure turbine by constructing non-axisymmetric endwalls to the stator row and the rotor *** optimization was quantified by using optimization algorithms based on the multi-objective *** objective was to increase total-to-total efficiency with the constraint on the mass flow rate equal to the design point *** order to ensure that global optimum could be achieved,the function of parameters was first approximated through the artificial neural network,and then optimum was achieved by implementing the genetic *** was adopted through the design and optimization environment of fineTM/Design3 *** individual treatments of the endwalls were ***,the hub and the shroud of the stator were optimized ***,the hub of the rotor was ***,the rotor hub was optimized in the presence of the optimized *** result of the investigation showed that the optimized shape of the endwalls can significantly help to increase the efficiency up to 0.18%with the help of a reduction of the transverse pressure *** coefficient of secondary kinetic energy,entropy coefficient,spanwise mass averaged entropy were *** order to investigate the periodic effects,the design of the optimized turbine under steady simulations was confirmed through unsteady *** last part of the investigation made sure that the performance improvement remained consistent over the full operating line at off-design conditions by the implementation of non-axisymmetric endwalls.

关键词： optimization non-axisymmetric endwall high pressure turbine stage efficiency secondary kinetic energy steady unsteady off-design

Electrostatic Dust Acoustic Solitons in Pair-Ion-Electron Plasmas

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Chinese Physics Letters 2012年第6期29卷 207-210页

作者： Hafeez Ur rehman Theoretical Plasma Physics Division Pakistan Institute of Nuclear Science and Technology(PINSTECH)P.O.NiloreIslamabadPakistan Department of Physics and Applied Mathematics Pakistan Institute of Engineering and Applied Sciences(PIEAS)P.O.NiloreIslamabadPakistan

Using the reductive perturbation method,a Korteweg-de Vries (KdV) equation is derived to study the nonlinear properties of electrostatic collisionless dust acoustic solitons in pair-ion-electron (p-i-e) *** Buid model is chosen for positive ions,negative ions,and the fraction of electrons and charged (both positive and negative)dynamic dust *** is realized that electrostatic hump structures can be found when the dust particles are positively charged,and electrostatic dip structures can be detected for negatively charged dust *** solutions for these dust acoustic solitous are plotted and their characteristics are *** is found that the amplitude and width of the electrostatic dust acoustic solitons increase when the density of the dust particles and/or the temperature of the negative ions increases,and that the amplitude and width of these solitons decrease when the temperature of the positive ions *** pair-ion plasmas mimic electron-positron plasmas,our results might be helpful in understanding the nonlinear dust acoustic solitary waves in super dense astronomical bodies like neutron stars.

关键词： particles electrostatic solitons

Quantum spin Hall and quantum valley Hall effects in trilayer graphene and their topological structures

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Chinese Physics B 2017年第12期26卷 481-490页

作者： Majeed Ur rehman A A Abid ICQD Hefei National Laboratory for Physical Sciences at Microscale Department of Physics University of Science and Technology of China Hefei 230026 China Key Laboratory of Geospace Environment(Chinese Academy of Sciences) Department of Geophysics and Planetary Science University of Science and Technology of China Hefei 230026 China

The present study pertains to the trilayer graphene in the presence of spin orbit coupling to probe the quantum spin/valley Hall effect. The spin Chern-number Cs for energy-bands of trilayer graphene having the essence of intrinsic spin-orbit coupling is analytically calculated. We find that for each valley and spin, Cs is three times larger in trilayer graphene as compared to single layer graphene. Since the spin Chern-number corresponds to the number of edge states, consequently the trilayer graphene has edge states, three times more in comparison to single layer graphene. We also study the trilayer graphene in the presence of both electric-field and intrinsic spin-orbit coupling and investigate that the trilayer graphene goes through a phase transition from a quantum spin Hall state to a quantum valley Hall state when the strength of the electric field exceeds the intrinsic spin coupling strength. The robustness of the associated topological bulk-state of the trilayer graphene is evaluated by adding various perturbations such as Rashba spin-orbit （RSO） interaction αR, and exchange-magnetization M. In addition, we consider a theoretical model, where only one of the outer layers in trilayer graphene has the essence of intrinsic spin-orbit coupling, while the other two layers have zero intrinsic spin-orbit coupling. Although the first Chern number is non-zero for individual valleys of trilayer graphene in this model, however, we find that the system cannot be regarded as a topological insulator because the system as a whole is not gaped.

关键词： trilayer graphene quantum spin Hall effect topological insulator quantum phase transition

Kinetics and mechanistic investigation of epoxide/CO2 cycloaddition by a synergistic catalytic effect of pyrrolidinopyridinium iodide and zinc halides

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Journal of Energy Chemistry 2019年第10期28卷 35-42页

作者： Abdul rehman Valentine C. Eze M.f.M.Gunam Resul Adam Harvey School of Engineering Merz CourtNewcastle UniversityNewcastle Upon Tyne NE1 7RUUK Department of Chemical and Polymer Engineering University of Engineering and Technology LahoreFaisalabad CampusPakistan

formation of styrene carbonate (SC) by the cycloaddition of CO2 to styrene oxide (SO) catalysed by pyrrolidinopyridinium iodide (PPI) in combination with zinc halides (ZnCl2, ZnBr2 and ZnI2) was investigated. Complete conversion of the SO to SC was achieved in 3 h with 100% selectivity using 1/0.5 molar (PPI/ZnI2) catalyst ratio under mild reaction conditions i.e., 100℃ and 10 bar CO2 pressure. The synergistic effect of ZnI2 and PPI resulted in more than 7-fold increase in reaction rate than using PPI alone. The cycloaddition reaction demonstrated the first-order dependence with respect to the epoxide, CO2 and catalyst concentrations. Moreover, the kinetic and thermodynamic activation parameters of SC formation were determined using the Arrhenius and Eyring equations. The positive values of △H(42.8 kJ mol^-1) and △G(102.3 kJ mol^-1) revealed endergonic and chemically controlled nature of the reaction, whereas the large negative values of △S(-159.4 J mol^-1 K^-1) indicate a highly ordered activated complex at the transition state. The activation energy for SC formation catalyzed by PPI alone was found to be 73.2 kJ mol^-1 over a temperature range of 100-140℃, which was reduced to 46.1 kJ mol^-1 when using PPI in combination with ZnI2 as a binary catalyst. Based on the kinetic study, a synergistic acid-based reaction mechanism was proposed.

关键词： Cycloaddition CO2 utilization Cyclic carbonates Homogeneous catalysis Activation energy

Effect of pressure on the electrical properties of flexible NiPc thin films fabricated by rubbing-in technology

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Chinese Physics B 2021年第1期30卷 328-331页

作者： Khasan S Karimov fahmi f Muhammadsharif Zubair Ahmad M Muqeet rehman Rashid Ali GIK Institute of Engineering Sciences and Technology TopiDistrict SwabiKPK23640Pakistan Center for Innovative Development of Science and New Technologies of Academy of Sciences of Tajikistan Dushanbe734025 Department of Physics Faculty of Science and HealthKoya University44023 KoyaKurdistan Region-F.R.Iraq Center for Advanced Materials(CAM) Qatar UniversityP.O.Box 2713DohaQatar Department of Electronic Engineering Jeju National UniversityJejuRepublic of Korea

Nickel phthalocyanine(Ni Pc) film was deposited onto the surface of flexible conductive glass by rubbing-in technology and used to fabricate devices based on ITO/Ni Pc/CNT/rubber structure. The I–V characteristics of the devices were investigated under different uniaxial pressures of 200, 280, and 480 gf/cm^(2), applied perpendicular to the surface of the Ni Pc film. Results showed that the nonlinearity coefficients of the I–V curves are in the range of 2 to 3, which was found to be decreased with the increase of the pressure. The rectification ratio of the devices was estimated to be varied from 1.5 to 3 based on the applied pressure. Concluding, the resistance of the active layers was decreased with the increase of both pressure and voltage. We believe that using the rubbing-in technology under sufficient applied pressure it is possible to utilize Ni Pc for the development of various electronic devices such as diodes, nonlinear resistors, and sensors.

关键词： pressure electrical property NiPc thin film rubbing-in technology

Gender disparities and woman-specific trends in Barrett’s esophagus in the United States:An 11-year nationwide populationbased study

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World Journal of Methodology 2025年第1期15卷 60-71页

作者： Karina fatakhova faisal Inayat Hassam Ali Pratik Patel Attiq Ur rehman Arslan Afzal Muhammad Sarfraz Shiza Sarfraz Gul Nawaz Ahtshamullah Chaudhry Rubaid Dhillon Arthur Dilibe Benjamin Glazebnik Lindsey Jones Emily Glazer Division of Gastroenterology and Hepatology Mather Hospital and Zucker School of Medicine at Hofstra UniversityPort JeffersonNY 11777United States Department of Internal Medicine Allama Iqbal Medical CollegeLahorePunjab 54550Pakistan Division of Gastroenterology and Hepatology East Carolina University Brody School of MedicineGreenvilleNC 27834United States Division of Gastroenterology and Hepatology Geisinger Wyoming Valley Medical CenterWilkes-BarrePA 18711United States Department of Internal Medicine East Carolina University Brody School of MedicineGreenvilleNC 27834United States Department of Internal Medicine St.Dominic's HospitalJacksonMS 39216United States Department of Gastroenterology Hepatologyand NutritionCleveland Clinic FoundationClevelandOH 44195United States Department of Internal Medicine Mather Hospital and Hofstra University ZuckerSchool of MedicinePort JeffersonNY 11777United States

BACKGROUND Barrett's esophagus(BE)is a known premalignant precursor to esophageal adenocarcinoma(EAC).The prevalence rates continue to rise in the United States,but many patients who are at risk of EAC are not *** practice guidelines include male gender as a predisposing factor for BE and *** population-based clinical evidence regarding female gender remains *** To study comparative trends of gender disparities in patients with BE in the United *** A nationwide retrospective study was conducted using the 2009-2019 National Inpatient Sample(NIS)*** with a primary or secondary diagnosis code of BE were *** major outcome of interest was determining the gender disparities in patients with *** analysis for respective outcomes for females was also reported to ascertain any time-based *** We identified 1204190 patients with BE for the study *** the included patients,717439(59.6%)were men and 486751(40.4%)were *** mean age was higher in women than in men(67.1±0.4 vs 66.6±0.3 years,Pf BE per 100000 total NIS hospitalizations for males increased from 144.6 in 2009 to 213.4 in 2019(Pfor females increased from 96.8 in 2009 to 148.7 in 2019(Pfrequency of obesity among women compared to men(17.4%vs 12.6%,Pfemales increased from 12.3%in 2009 to 21.9%in 2019(Pf smoking was noted in women than in men(20.8%vs 35.7%,Pf smoking among women,from 12.9%in 2009 to 30.7%in 2019(Pf alcohol abuse,Helicobacter pylori(***),and diabetes mellitus among females than males(Pf alcohol use disorder and a decreasing prevalence of *** and diabetes mellitus among women(Pf BE among

关键词： Barrett’s esophagus Gender disparity Epidemiological trends Esophageal adenocarcinoma Screening endoscopy female gender Risk factors

Investigation of ZrO2 nanoparticles concentration and processing time effect on the localized PEO coatings formed on AZ91 alloy

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Journal of Magnesium and Alloys 2019年第4期7卷 555-565页

作者： Zeeshan Ur rehman Dongjin Choi School of Materials Science and Engineering Hongik UniversitySejongRepublic of Korea

AZ91 Mg alloy was treated through a new localized PEO(Plasma Electrolytic Oxidation)coating approach,using electrolyte solutions with varying ZrO2 nanoparticles concentration(2-8 g/L)and processing *** increase in the ZrO2 concentration,several microstructural changes were observed including;formation of cluster-type structure,damage to the inner layers(∼30 min)and sealing of *** analysis of the final coatings was carried out using potentiodynamic polarization,electrochemical impedance spectroscopy and post-corrosion *** was explored that highest corrosion resistance(Rp∼81.17 kΩcm^2)of the coatings was obtained for ZrO2∼2 g/***,higher concentration of the ZrO2 nanoparticles caused weak crystalline coating structure,due to unstable and lower intensity discharges,thus failed to offer high corrosion resistance performance.

关键词： Magnesium alloy PEO coating ZrO2 Corrosion Nanoparticles addition