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Miscibility and Molecular Orientation of Carbazole in Mixed Langmuir and Langmuir-Blodgett Films

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Chinese Physics Letters 2007年第7期24卷 2044-2047页

作者： md. N. Islam d. Bhattachaxjee s. A. Hussain department of Physics Tripura University Suryamaninagar-799130 Tripura India

We report the miscibility and molecular orientation of carbazole （CA） molecules in the mixed Langmuir and Langmuir-Blodgett （LB） films of CA in polymethyl methacrylate （PMMA） and stearic acid （sA） matrices. The lr-A isotherm confirms the formation of stable Langmuir films of CA mixed with either PMMA or sA at airwater interface. ＇Characteristics of area per molecule versus molefraction and collapse pressure versus molefraction reveal complete demixing of CA and the matrix PMMA/sA molecules in the mixed films. Absorption spectroscopy certainly confirms the fact that CA molecules have preferred orientation on the substrate of the LB films.

关键词： ELECTROLUMINEsCENT dEVICEs ENERGY-TRANsFER

surface settlement induced by horizontal directional drilling

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Underground space 2023年第1期8卷 94-108页

作者： Asif Ahmed md Azijul Islam md Zahangir Alam Hashmi s.Quazi College of Engineering State University of New York Polytechnic Institute(SUNY Poly)UticaNY 13502USA department of Civil Engineering The University of Texas at ArlingtonArlingtonTX 76019USA department of Civil Engineering Bangladesh University of Engineering and Technology(BUET)Dhaka 1000Bangladesh Converse Consultants RedlandsCA 92373USA

Horizontal directional drilling(Hdd)is a widely us.d.trenchless method for underground utility *** associated ground settlement triggered by Hdd depends on the size,types,and surface texture of pipe,diameter of borehole,and soil *** pre-sent study investigates the surface settlement due to the construction of a 1067 mm diameter Hdd,which will replace an existing sewer siphon under the sR-60 highway in Chino,California using empirical,and numerical *** on the results obtained from the subsurface investigation,an empirical analysis was conducted *** by numerical modeling of the Hdd using PLAXIs 2d soft-ware.A careful comparison between two different methods indicated closer values of surface settlement between the empirical method(7.3 mm)and the numerical modeling(4.6 mm).In addition,the shape of surface settlement and horizontal settlement curves for the empirical and numerical methods was found to be *** minor discrepancy between the two methods resulted as the numerical model can host several soil layers whereas the empirical equation can use only one type of ***,a parametric study was conducted to evaluate the effect of borehole cover depth,size,and soil parameters on surface *** was observed that soil strength param-eters yielded a greater effect on surface movement,whereas modulus of elasticity has a relatively smaller influence with zero contribution from Poisson’s ratio.

关键词： Horizontal directional drilling(Hdd) surface settlement Cover depth soil arching Borehole

A study on the Gas-solid Particle Flows in a Needle-Free drug delivery device

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Journal of Thermal science 2013年第4期22卷 340-344页

作者： md.Alim Iftekhar Rasel md.Abu Taher H.d.Kim department of Mechanical Engineering Andong National University

different systems have been us.d.over the years to deliver drug particles to the human skin for pharmaceutical effect. Research has been done to improve the performance and flexibility of these systems. In recent years a unique system called the transdermal drug delivery has been developed. Transdermal drug delivery opened a new door in the field of drug delivery as it is more flexible and offers better performance than the conventional systems. The principle of this system is to accelerate drug particles with a high speed gas flow. Among different transdermal drug delivery systems we will concentrate on the contour shock tube system in this paper. A contoured shock tube is consists of a rupture chamber, a shock tube and a supersonic nozzle section. The drug particles are retained between a set of bursting diaphragm. When the diaphragm is ruptured at a certain pressure, a high speed unsteady flow is initiated through the shock tube which accelerates the particles. Computational fluid dynamics is us.d.to simulate and analyze the flow field. The dPM (discrete phase method) is us.d.to model the particle flow. As an unsteady flow is initiated though the shock tube the drag correlation propos.d.by Igra et al is us.d.other than the standard drag correlation. The particle velocities at different sections including the nozzle exit are investigated under different operating conditions. static pressure histories in different sections in the shock tube are investigated to analyze the flow field. The important aspects of the gas and particle dynamics in the shock tube are discuss.d.and analyzed in details.

关键词： shock tube drug delivery Contoured shock tube Unsteady flow Biolistics

Insights into the physical properties and anisotropic nature of ErPdBi with an appearance of low minimum thermal conductivity

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Chinese Physics B 2021年第1期30卷 398-406页

作者： s K Mitro R Majumder K M Hossain md Zahid Hasan md Emran Hossain M A Hadi Bangamata sheikh Fojilatunnesa Mujib science and Technology University Jamalpur-2012Bangladesh Physics.d.scipline Khulna UniversityKhulna-9208Bangladesh department of Materials science and Engineering University of RajshahiRajshahi-6205Bangladesh department of Electrical and Electronic Engineering International Islamic University ChittagongKumiraChittagong-4318Bangladesh department of Physics University of RajshahiRajshahi6205Bangladesh

We theoretically study the structural, elastic and optical properties of Er Pd Bi together with its anisotropic behaviors using density functional theory. It is observed that Er Pd Bi satisfies the Born stability criteria nicely and possesses high quality of machinability. The anisotropic behavior of Er Pd Bi is reported with the help of theoretical anisotropy indices incorporating 3 d graphical presentation, which suggests that Er Pd Bi is highly anisotropic in nature. It is noticed that the minimum thermal conductivity is very low for Er Pd Bi compared to the several species. This low value of minimum thermal conductivity introduces the potentiality of Er Pd Bi in high-temperature applications such as thermal barrier *** addition, deep optical insights of Er Pd Bi reveal that our material can be us.d.in different optoelectronic and electronic device applications ranging from organic light-emitting diodes, solar panel efficiency, waveguides etc. to integration of integrated circuits. Therefore, we believe that our results will provide a new insight into high-temperature applications and will benefit for the development of promising optoelectric devices as well.

关键词： Er Pd Bi minimum thermal conductivity anisotropy density functional theory(dFT)

dielectric relaxation and conduction mechanism in Aurivillius ceramic Bi_(5)Ti_(3)FeO_(15)

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International Journal of Minerals,Metallurgy and Materials 2021年第6期28卷 1063-1071页

作者： Rasmita Jena K.Chandrakanta P.Pal md.F.Abdullah s.d.Kaushik A.K.singh department of Physics and Astronomy National Institute of Technology RourkelaRourkela-769008OdishaIndia UGC-dAE Consortium for scientific Research Mumbai Centre BARCMumbai-400085India

For this study,we synthesized Aurivillius Bi_(5)Ti_(3)FeO_(15) ceramic using the generic solid-state reaction route and then performed roomtemperature X-ray diffraction to confirm that the compound had a single phase with no *** surface morphology of the prepared sample was observed to contain microstructural grains approximately 0.2–2μm in *** dielectric properties of the sample were determined as a function of frequency in a range of approximately 100 Hz to 1 MHz at various temperatures(303 K≤T≤773 K).Nyquist plots of the impedance data were found to exhibit a semi-circular arc in the high-temperature region,which is explained by the equivalent electrical circuit(R_(1)C_(1))(R_(2)QC_(2)),where R_(1) and R_(2) represent the resistances associated with the grains and grain boundaries,respectively,C_(1) and C_(2) are the respective capacitances,and Q is the constant phase element(CPE),which accounts for non-debye type of *** results indicate that both the resistance and capacitance of the grain boundaries are more prominent than those of the *** alternating current(ac)conductivity data were analyzed bas.d.on the Jonscher universal power law,which indicated that the conduction process is.d.minated by the hopping *** calculated activation energies of the relaxation and conduction processes were very similar(0.32 to 0.53 eV),from which we conclude that the same type of charge carriers are involved in both processes.

关键词： Nyquist plot impedance spectroscopy activation energy ac conductivity hopping

Particles.d.spersion on fluid-liquid interfaces

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Particuology 2011年第1期9卷 1-13页

作者： sathish Gurupatham Bhavin dalal md.shahadat Hossain Ian s.Fischer Pushpendra singh daniel d.Joseph department of Mechanical Engineering New Jersey Institute of Technology department of Aerospace Engineering and Mechanics University of Minnesota department of Mechanical and Aerospace Engineering University of California Irvine

This paper is concerned with the dispersion of particles on the fluid-liquid interface. In a previous study we have shown that when small particles, e.g., flour, pollen, glass beads, etc., contact an air-liquid interface, they disperse rapidly as if they were in an explosion. The rapid dispersion is.d.e to the fact that the capillary force pulls particles into the interface causing them to accelerate to a large velocity. In this paper we show that motion of particles normal to the interface is inertia dominated; they oscillate vertically about their equilibrium position before coming to rest under viscous.d.ag. This vertical motion of a particle causes a radially-outward lateral （secondary） flow on the interface that causes nearby particles to move away. The dispersion on a liquid-liquid interface, which is the primary focus of this study, was relatively weaker than on an air-liquid interface, and occurred over a longer period of time. When falling through an upper liquid the particles have a slower velocity than when falling through air because the liquid has a greater viscosity. Another difference for the liquid-liquid interface is that the separation of particles begins in the upper liquid before the particles reach the interface. The rate of dispersion depended on the size of the particles, the densities of the particle and liquids, the viscosities of the liquids involved, and the contact angle. For small particles, partial pinning and hysteresis of the three-phase contact line on the surface of the particle during adsorption on liquid-liquid interfaces was also important. The frequency of oscillation of particles about their floating equilibrium increas.d.with decreasing particle size on both air-water and liquid-liquid interfaces, and the time to reach equilibrium decreas.d.with decreasing particle size. These results are in agreement with our analysis.

关键词： Adsorption Interfacial tension Particle dispersion Fluid–liquid interface Capillary force Viscous.d.ag

Miscibility of Two Components in a Binary Mixture of 9-Phenyl Anthracene Mixed with stearic Acid or Polymethyl Methacrylate at Air-Water Interface

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Chinese Physics Letters 2007年第5期24卷 1331-1334页

作者： P. K. Paul md. N. Islam d. Bhattacharjee s. A. Hussain department of Physics Tripura University Suryamaninagar-799130 Tripura India

We report the miscibility characteristics of two components in a binary mixture of 9-phenyl anthracene （PA） mixed with stearic acid （sA） or polymethyl methacrylate （PMMA）. The behaviour of surface pressure versus area per molecule isotherms reveal that the area per molecule decreases systematically with increasing molefractions of PA. The characteristics of areas per molecule versus molefractions and collapse pressure vs molefraction indicate that various interactions involved among the sample and matrix molecules. The interaction scheme is found to change with the change in surface pressure and molefraction of mixing. scanning electron microscopic study confirms the aggregation of PA molecules in the mixed films.

关键词： LANGMUIR-BLOdGETT-FILMs sPECTROsCOPIC CHARACTERIZATIONs MOLECULEs sYsTEMs

Effect of Co substitution on the structural,dielectric and optical properties of KBiFe_(2)O_(5)

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International Journal of Minerals,Metallurgy and Materials 2021年第11期28卷 1861-1867页

作者： K.Chandrakanta R.Jena P.Pal md.F.Abdullah s.d.Kaushik A.K.singh department of Physics and Astronomy National Institute of TechnologyRourkela-769008OdishaIndia UGC-dAE Consortium for scientific Research Mumbai Centre R-5 ShedBARCMumbai-400085India

Cobalt(Co)-modified brownmillerite KBiFe_(2)O_(5)(KBFO;[KBiFe_(2(1−x))Co_(2x)O_(5)(x=0,0.05)])polycrystalline is synthesized following the solid-state reaction *** refinement of X-ray diffraction data confirmed the phase purity of KBFO and KBiFe_(1.9)Co_(0.1)O_(5)(KBFCO).The optical bandgap energy(Eg)of KBFO decreas.d.from 1.59 to 1.51 eV because of Co *** decrease in bandgap can be attributed to the tilting of the Fe–O tetrahedral structure of *** observed room-temperature Raman peaks of KBFCO shifted by 3 cm^(−1) toward a lower wavenumber than that of *** shift in Raman active modes can be attributed to the change in the bond angles and bond lengths of the Fe–O tetrahedral structure and modification in response to oxygen deficiency in KBFO because of Co *** with that of KBFO,the frequency-dependent dielectric constant and dielectric loss of KBFCO decrease at room temperature,which is a consequence of the reduction in oxygen migration and modification in response to vibrational modes present in the sample.

关键词： brownmillerite rietveld refinement Raman spectroscopy bandgap

Redox dysregulation as a driver for dNA damage and its relationship to neurodegenerative diseases

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Translational Neurodegeneration 2023年第1期12卷 604-637页

作者： sina shadfar sonam Parakh md shafi Jamali Julie d.Atkin Centre for Motor Neuron disease Research Macquarie Medical SchoolMacquarie UniversitySydneyNSW 2109Australia La Trobe Institute for Molecular science La Trobe UniversityBundooraMelbourneVIC 3086Australia

Redox homeostasis refers to the balance between the production of reactive oxygen species(ROs)as well as reactive nitrogen species(RNs),and their elimination by *** is linked to all important cellular activities and oxidative stress is a result of imbalance between pro-oxidants and antioxidant *** stress perturbs many cellular activities,including processes that maintain the integrity of *** acids are highly reactive and therefore particularly susceptible to *** dNA damage response detects and repairs these dNA *** dNA repair processes are therefore essential for maintaining cellular viability,but they decline cons.d.rably during *** damage and deficiencies in dNA repair are increasingly described in age-related neurodegenerative diseases,such as Alzheimer’s.d.sease,Parkinson’s.d.sease,amyotrophic lateral sclerosis and Huntington’s ***,oxidative stress has long been associated with these ***,both redox dysregulation and dNA damage increase significantly during aging,which is the biggest risk factor for neurodegenerative ***,the links between redox dysfunction and dNA damage,and their joint contributions to pathophysiology in these conditions,are only just *** review will discuss these associations and address the increasing evidence for redox dysregulation as an important and major source of dNA damage in neurodegenerative *** these connections may facilitate a better understanding of disease mechanisms,and ultimately lead to the design of better therapeutic strategies bas.d.on preventing both redox dysregulation and dNA damage.

关键词： Redox dysregulation dNA damage Neurodegeneration Reactive oxygen species Oxidative stress