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Applied mathematics and mechanics(English Edition) 2025年第1期46卷 193-208页

作者： k.mUHAmmAD m.sARFRAZ Department of Humanities and sciences School of Electrical Engineering and Computer Science National University of Sciences and Technology Department of mathematics Quaid-i-Azam University

This article presents a mathematical model addressing a scenario involving a hybrid nanofluid flow between two infinite parallel plates. One plate remains stationary, while the other moves downward at a squeezing velocity. The space between these plates contains a Darcy-Forchheimer porous medium. A mixture of water-based fluid with gold(Au) and silicon dioxide(si O2) nanoparticles is formulated. In contrast to the conventional Fourier's heat flux equation, this study employs the Cattaneo-Christov heat flux equation. A uniform magnetic field is applied perpendicular to the flow direction, invoking magnetohydrodynamic(mHD) effects. Further, the model accounts for Joule heating, which is the heat generated when an electric current passes through the fluid. The problem is solved via NDsolve in mATHEmATICA. Numerical and statistical analyses are conducted to provide insights into the behavior of the nanomaterials between the parallel plates with respect to the flow, energy transport, and skin *** findings of this study have potential applications in enhancing cooling systems and optimizing thermal management strategies. It is observed that the squeezing motion generates additional pressure gradients within the fluid, which enhances the flow rate but reduces the frictional drag. Consequently, the fluid is pushed more vigorously between the plates, increasing the flow velocity. As the fluid experiences higher flow rates due to the increased squeezing effect, it spends less time in the region between the plates. The thermal relaxation, however, abruptly changes the temperature, leading to a decrease in the temperature fluctuations.

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New ternary superconducting compound LaRu2As2： Physical properties from density functional theory calculations

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Chinese Physics B 2017年第3期26卷 453-460页

作者： m A Hadi m s Ali s H Naqib A k m A islam Department of Physics University of Rajshahi Rajshahi 6205 Bangladesh Department of Physics Pabna University of Science and Technology Pabna 6600 Bangladesh International islamic University Chittagong Chittagong 4203 Bangladesh

In this paper, we perform the density functional theory （DFT） -based calculations by the first-principles pseudopo- tential method to investigate the physical properties of the newly discovered superconductor LaRu2As2 for the first time. The optimized structural parameters are in good agreement with the experimental results. The calculated independent elas- tic constants ensure the mechanical stability of the compound. The calculated Cauchy pressure, Pugh＇s ratio as well as Poisson＇s ratio indicate that LaRu2As2 should behave as a ductile material. Due to low Debye temperature, LaRu2As2 may be used as a thermal barrier coating （TBC） material. The new compound should exhibit metallic nature as its valence bands overlap considerably with the conduction bands. LaRu2As2 is expected to be a soft material and easily machinable because of its low hardness value of 6.8 GPa. The multi-band nature is observed in the calculated Fermi surface. A highly anisotropic combination of ionic, covalent and metallic interactions is expected to be in accordance with charge density calculation.

关键词： new superconductor LaRu2As2 density functional theory (DFT) calculations mechanical proper-ties electronic features

Band structure,Fermi surface,elastic,thermodynamic,and optical properties of AlZr3,AlCu3,and AlCu2Zr:First-principles study

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Chinese Physics B 2016年第8期25卷 103-112页

作者： Parvin R Parvin F Ali m s islam A k m A Department of Physics Rajshahi University Rajshahi-6205 Bangladesh Department of Physics Pabna University of Science and Technology Pabna 6600 Bangladesh International islamic University Chittagong 154/A College Road Chittagong-4203 Bangladesh

The electronic properties（Fermi surface,band structure,and density of states（DOs）） of Al-based alloys Alm3（m=Zr and Cu） and AlCu2Zr are investigated using the first-principles pseudopotential plane wave method within the generalized gradient approximation（GGA）.The structural parameters and elastic constants are evaluated and compared with other available ***,the pressure dependences of mechanical properties of the compounds are *** temperature dependence of adiabatic bulk modulus,Debye temperature,specific heat,thermal expansion coefficient,entropy,and internal energy are all obtained for the first time through quasi-harmonic Debye model with phononic effects for T = 0 k-100 *** parameters of optical properties（dielectric functions,refractive index,extinction coefficient,absorption spectrum,conductivity,energy-loss spectrum,and reflectivity） of the compounds are calculated and discussed for the first *** reflectivities of the materials are quite high in the IR-visible-UV region up to ~ 15 eV,showing that they promise to be good coating materials to avoid solar *** of the properties are also compared with those of the Al-based Ni3 Al compound.

关键词： first principle calculations Fermi surface elastic moduli entropy and internal energy optical properties

The Two-Dimensional supersonic Flow and mixing with a Perpendicular Injection in a scramjet Combustor

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Journal of Thermal science 2003年第4期12卷 371-380页

作者： mohammad Ali s. Ahmed A.k.m. sadrul islam Department of mechanical Engineering Bangladesh University of Engineering and Technology (BUET) Dhaka-1000 Bangladesh.Department of Mechanical Engineering Bangladesh University of Engineering and Technology (BUET) Dhaka-1000 Bangladesh.Department of Mechanical Engineering Bangladesh University of Engineering and Technology (BUET) Dhaka-1000 Bangladesh.

A numerical investigation has been performed on supersonic mixing of hydrogen with air in a scramjet (supersonic Combustion Ramjet) combustor and its flame holding capability by solving Two-Dimensional full Navier-stokes equations. The main flow is air entering through a finite width of inlet and gaseous hydrogen is injected perpendicularly from the side wall. An explicit Harten-Yee Non-mUsCL modified-flux-type TVD scheme has been used to solve the system of equations, and a zero-equation algebraic turbulence model to calculate the eddy viscosity coefficient. In this study the enhancement of mixing and good flame holding capability of a supersonic combustor have been investigated by varying the distance of injector position from left boundary keeping constant the backward-facing step height and other calculation parameters. The results show that the configuration for small distance of injector position has high mixing efficiency but the upstream recirculation can not evolved properly which is an important factor for flame holding capability. On the other hand, the configuration for very long distance has lower mixing efficiency due to lower gradient of hydrogen mass concentration on the top of injector caused by the expansion of side jet in both upstream and downstream of injector. For moderate distance of injector position, large and elongated upstream recirculation can evolve which might be activated as a good flame holder.

关键词： scramjet engine TVD scheme finite width of inlet supersonic mixing parallel air stream flame holding.

An ab initio investigation of vibrational, thermodynamic, and optical properties of sc_2AlC mAX compound

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Chinese Physics B 2016年第10期25卷 103-108页

作者： m A Ali m T Nasir m R khatun A k m A islam s H Naqib Department of Physics Chittagong University of Engineering and Technology Department of Arts & sciences Bangladesh Army University of Science and Technology Department of Physics University of Rajshahi International islamic University Chittagong

The structural vibrational, thermodynamical, and optical properties of potentially technologically important, weakly coupled mAX compound, sc2 Al C are calculated using density functional theory(DFT). The structural properties of scAlC are compared with the results reported earlier. The vibrational, thermodynamical, and optical properties are theoretically estimated for the first time. The phonon dispersion curve is calculated and the dynamical stability of this compound is investigated. The optical and acoustic modes are observed clearly. We calculate the Helmholtz free energy(F), internal energy(E), entropy(s), and specific heat capacity(Cv) from the phonon density of states. Various optical parameters are also calculated. The reflectance spectrum shows that this compound has the potential to be used as an efficient solar reflector.

关键词： mAX compound phonon dispersion thermodynamical properties optical properties

Impact of Zika virus non-structural protein mutations on hippocampal damage

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Neural Regeneration Research 2025年第8期20卷 2307-2308页

作者： Larissa m.G.Cassiano Roney s.Coimbra Neurogenômica/Imunopatologia Instituto RenéRachouFiocruzBelo HorizonteBrazil Departamento de Bioquímica e Imunologia Instituto de Ciências BiológicasUniversidade Federal de Minas GeraisBelo HorizonteBrazil

The Zika virus(ZIkV),a member of the Flaviviridae family,attracted worldwide attention for its connection to severe neurological effects,notably microcephaly in newborns,first reported during the 2015 epidemic in ***,its impact goes beyond fetal and neonatal abnormalities,also affecting the central nervous system(CNs)in both children and adults,leading to enduring cognitive and behavioral impairments.

关键词： damage fetal neonatal

Pre-sowing treatments for improved germination and growth of two rare native species of Bangladesh

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Journal of Forestry Research 2018年第5期29卷 1277-1282页

作者： m.A.Hossain k.s.islam N.Rajasree m.k.Hossain m.s.Alam Institute of Forestry and Environmental sciences University of Chittagong

Pre-sowing treatments are expected to increase seed *** evaluates response to pre-sowing treatments and the growth performance of two native and rare tree species,Garuga pinnata *** Vitex glabrata *** hard seed coats were treated by rubbing with sand paper,nail clipping,and immersion in water and acid（H_2sO_4）.Results indicate that *** showed a 90% germination rate and 30% germination energy when seed coats were nicked with a nail *** with sand paper was the best pre-sowing treatment for ***,resulting a 80% germination rate and 30% germination *** and *** seedlings from seeds soaked 24h in water resulted in maximum heights and collar *** were significantly higher（at p〈0.05） than those of other *** results indicate that scarification or nicking of seeds may have some negative impacts on seedling ***,it is difficult to recommend a pre-sowing treatment of seeds for achieving both maximum germination and good early seedling growth.

关键词： Germination Early seedling growth Height Native species Garuga pinnata Vitex glabrata

mechanical and thermodynamical stability of BiVO4 polymorphs using first-principles study

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Chinese Physics B 2017年第3期26卷 395-403页

作者： A k m Farid UI islam md Nurul Huda Liton H m Tariqul islam md Al Helal md kamruzzaman Department of Computer science and Engineering Begum Rokeya University Rangpur Rangpur-5400 Bangladesh Department of Physics Begum Rokeya University Rangpur Rangpur-5400 Bangladesh Department of Chemistry Begum Rokeya University Rangpur Rangpur-5400 Bangladesh Department of Physics and materials science and Center of super-Diamond and Advanced Films (COsDAF) City University of Hong Kong Hong Kong SAR China

First principles calculations of structural, electronic, mechanical, and thermodynamic properties of different poly- morphs of BiVO4 are performed using Bender-type plane/wave ultrasoft pseudopotentials within the generalized gradient approximation （GGA） in the flame of density functional theory （DFT）. The calculated structural and electronic properties are consistent with the previous theoretical and experimental results. The electronic structures reveal that m-BiVO4, op- BiVO4, and st-BiVO4 have indirect band gaps, on the other hand, zt-BiVO4 has a direct band gap. From the DOs and mulliken＇s charge analysis, it is observed that only m-BiVO4 has 6s2 Bi lone pair. Bond population analysis indicates that st-BiVO4 shows a more ionic nature and a similar result is obtained from the elastic properties. From the elastic prop- erties, it is observed that st-BiVO4 is more mechanically stable than the others, st-BiVO4 is more ductile and useful for high electro-optical and electro-mechanical coupling devices. Our calculated thermodynamic properties confirm the similar characteristics found from electronic and elastic properties, m-BiVO4 is useful as photocatalysts, solid state electrolyte, and electrode and other polymorphs are applicable in electronic device fabrications.

关键词： BiVO4 crystal structure lone pair mechanical stability

Determination of volatile organic compounds in river water by solid phase extraction and gas chromatography

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Journal of Environmental sciences 2004年第3期16卷 497-501页

作者： m.A.mottaleb m.Z.Abedin m.s.islam Department of Chemistry Department of Chemical Technology and Polymer SciencesDepartment of Chemical Technology and Polymer Sciences University of RajshahiRajshahi 6205 BangladeshDept.of Chemistry and BiochemistryBaylor UniversityWacoUSAShahjalal University of Science and TechnologySylhet 3114BangladeshShahjalal University of Science and TechnologySylhet 3114Bangladesh

A simple, rapid, and reproducible method is described employing solid phase extraction(sPE) using dichloromethane followed by gas chromatography(GC) with flame ionization detection(FID) for determination of volatile organic compound(VOC) from the Buriganga River water of Bangladesh. The method was applied to detect the benzene, toluene, ethylbenzene, xylene and cumene(BTEXC) in the sample collected from the surface or 15 cm depth of water. Two hundred ml of n hexane pretreated and filtered water samples were applied directly to a C 18 sPE column. BTEXC were extracted with dichloromethane and average concentrations were obtained as 0 104 to 0 372 μg/ml. The highest concentration of benzene was found as 0 372 μg/ml with a relative standard deviation(RsD) of 6 2%, and cumene was not detected. Factors influencing sPE e.g., adsorbent types, sample load volume, eluting solvent, headspace and temperatures, were investigated. A cartridge containing a C 18 adsorbent and using dichloromethane gave better performance for extraction of BTEXC from water. Average recoveries exceeding 90% could be achieved for cumene at 4℃ with a 2 7% RsD.

关键词： solid phase extraction river water environmental analysis VOC recoveries