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Chinese Physics Letters 2019年第6期36卷 93-97页

作者： o.ozturk e.ozturk S.elagoz Department of Nanotechnology engineering Cumhuriyet University Department of Physics Cumhuriyet University ASeLSAN-Microelectronics Guidance & Electro-Optics

For square-step quantum wells(SSQWs) and graded-step quantum wells(GSQWs), the nonlinear optical rectification(NoR), second harmonic generation(SHG) and third harmonic generation(THG) coefficients under an intense laser field(ILF) are analyzed. The found results indicate that ILF can ensure a vital influence on the shape and height of the confined potential profile of both SSQWs and GSQWs, and alterations of the dipole moment matrix elements and the energy levels are adhered on the profile of the confined potential. According to the results, the potential profile and height of the GSQWs are affected more significantly by ILF intensity compared to SSQWs. These results indicate that NoR, SHG and THG coefficients of SSQWs and GSQWs may be calibrated in a preferred energy range and the magnitude of the resonance peak(RP) by tuning the ILF parameter. It is feasible to classify blue or red shifts in RP locations of NoR, SHG and THG coefficients by varying the ILF parameter. our results can be useful in investigating new ways of manipulating the opto-electronic properties of semiconductor QW devices.

关键词： square-step quantum wells(SSQWs) graded-step quantum wells(GSQWs) nonlinear optical rectification(NoR)

Generalized quantum mechanical two-Coulomb-center problem (Demkov problem)

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Chinese Physics B 2013年第9期22卷 245-251页

作者： A.M.Puchkov A.V.Kozedub e.o.Bodnia Theoretical Department Institute of PhysicsSt. Petersburg State University Department of Computational Physics Faculty of PhysicsSt. Petersburg State University

We present a new exactly solvable quantum problem for which the Schrtidinger equation allows for separation of variables in oblate spheroidal coordinates. Namely, this is the quantum mechanical two-Coulomb-center problem for the case of an imaginary intercenter parameter and complex conjugate charges are considered. Since the potential is defined by the two-sheeted mapping whose singularities are concentrated on a circle rather than at separate points, there arise additional possibilities in the choice of boundary conditions. A detailed classification of the various types of boundary-value problems is given. The quasi-radial equation leads to a new type of boundary value problem which has never been considered before. Results of the numerical calculations, which allow conclusions to be drawn about the structure of the energy spectrum, are shown. Possible physical applications are discussed.

关键词： two-Coulomb-center problem potential models

Lattice dynamical and thermodynamical properties of ReB_2,RuB_2,and osB_2 compounds in the ReB_2 structure

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Chinese Physics B 2012年第10期21卷 355-361页

作者： e.Deligoz K.Colakoglu Y.o.Ciftci Department of Physics Aksaray University68100AksarayTurkey Department of Physics Gazi UniversityTeknikokullar06500AnkaraTurkey

Structural and lattice dynamical properties of ReB2,RuB2,and osB2 in the ReB2 structure are studied in the framework of density functional theory within the generalized gradient *** present results show that these compounds are dynamically stable for the considered *** temperature-dependent behaviors of thermodynamical properties such as internal energy,free energy,entropy,and heat capacity are also *** obtained results are in good agreement with the available experimental and theoretical data.

关键词： ab initio calculations lattice dynamical properties thermodynamical properties diborides

Synergistic effect of Metal Nanoparticles on the Antimicrobial Activities of Antibiotics against Biorecycling Microbes

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Journal of Materials Science & Technology 2016年第6期32卷 524-532页

作者： Chandni Khurana Purnima Sharma o.e Pandey Bhupendra Chudasama Laboratory of Nanomedicine School of Physics and Materials ScienceThapar UniversityPatiala 147004India Department of Applied Sciences Chandigarh UniversityMohali 160055India Department ofBiotechnology Thapar UniversityPatiala 147004India

Biorecycling microbes, which have critical functionalities in natural cycles, are essential to sustain eco-system of the earth. Any alterations in these cycles caused by the mutations of microbes could be a potential threat to life on earth. Antibiotics leached from pharmaceutical waste, animal food and agribusiness prod- ucts are accumulating in the environment. Metal nanoparticles are also accumulating in environment because of their extensive use as biocidal agent in domestic products. Interaction of antibiotics and metal nanoparticles with eco-ffiendly microorganisms has a potential to alter the ecosystem of the earth. In this article, we have studied the antibacterial activities of silver and copper nanoparticles and their for- mulations with antibiotics, tetracycline, and kanamycin against biorecycling microbes, Bacillus subtilis and Pseudomonas fluorescens. Strong synergistic effect of metal nanoparticles on the antimicrobial ac- tivities of commercial antibiotics has been observed. Antimicrobial activity of tetracycline improves by 286%-346% and 0%-28% when being tested in the presence of 250 ppm of silver and copper nanoparticles, respectively. For kanamycin, the improvement is 154%-289% for silver and 3%-20% for copper nanoparticles. Irrespective of the antibiotics and tested organisms, synergy is more prominent for silver nanoparticles even at their minimum active concentration （100 ppm）. This study demonstrates that the combination of metal nanoparticles with antibiotics could be more fatal to ecosystem than either the metal nanoparticles or the antibiotics alone.

关键词： Synergy Nanoparticles Antibiotics Biorecycling microbes Antibacterial activities

Numerical Simulation of the Tip Aerodynamics and Acoustics Test

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Journal of Thermal Science 2016年第2期25卷 153-160页

作者： F Tejero e P Doerffer o Szulc J L Cross The Szwalski Institute of Fluid-Flow Machinery Polish Academy of Sciences. Fiszera 14 80-231 Gdansk Poland NASA Ames Research Center (retired) Moffett Field CA USA

The application of an efficient flow control system on helicopter rotor blades may lead to improved aerodynamic performance. Recently, our invention of Rod Vortex Generators(RVGs) has been analyzed for helicopter rotor blades in hover with success. As a step forward, the study has been extended to forward flight conditions. For this reason, a validation of the numerical modelling for a reference helicopter rotor(without flow control) is needed. The article presents a study of the flow-field of the AH-1G helicopter rotor in low-, medium- and high-speed forward flight. The CFD code FLoWer from DLR has proven to be a suitable tool for the aerodynamic analysis of the two-bladed rotor without any artificial wake modelling. It solves the URANS equations with LeA(Linear explicit Algebraic stress) k-ω model using the chimera overlapping grids technique. Validation of the numerical model uses comparison with the detailed flight test data gathered by Cross J. L. and Watts M. e. during the Tip Aerodynamics and Acoustics Test(TAAT) conducted at NASA in 1981. Satisfactory agreements for all speed regimes and a presence of significant flow separation in high-speed forward flight suggest a possible benefit from the future implementation of RVGs. The numerical results based on the URANS approach are presented not only for a popular, low-speed case commonly used in rotorcraft community for CFD codes validation but preferably for medium- and high-speed test conditions that have not been published to date.

关键词： AH-1G TAAT helicopter rotor forward flight chimera overlapping grid

Proportional-integral-derivative control of nonlinear half-car electro-hydraulic suspension systems

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2013年第6期14卷 401-416页

作者： John e. D. eKoRU Jimoh o. PeDRo School of Mechanical Aeronautical and Industrial Engineering University of the Witwatersrand Private Bag 03 WITS 2050 Johannesburg South Africa

This paper presents the development of a proportional-integral-derivative (PID)-based control method for application to active vehicle suspension systems (AVSS). This method uses an inner PID hydraulic actuator force control loop, in combination with an outer PID suspension travel control loop, to control a nonlinear half-car AVSS. Robustness to model uncertainty in the form of variation in suspension damping is tested, comparing performance of the AVSS with a passive vehicle suspension system (PVSS), with similar model parameters. Spectral analysis of suspension system model output data, obtained by performing a road input disturbance frequency sweep, provides frequency response plots for both nonlinear vehicle suspension systems and time domain vehicle responses to a sinusoidal road input disturbance on a smooth road. The results show the greater robustness of the AVSS over the PVSS to parametric uncertainty in the frequency and time domains.

关键词： Force control Proportional-integral-derivative (PID) control Nonlinear half-car Active vehicle suspension system (AVSS) Hydraulic actuator dynamics Model uncertainty

Main immunomodulatory constituents of eastern Nigeria Mistletoe,Loranthus micranthus Linn

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Asian Pacific Journal of Tropical Medicine 2009年第4期2卷 11-18页

作者： P.o.osadebe e.o.omeje Department of Pharmaceutical and Medicinal Chemistry Faculty of Pharmaceutical SciencesUniversity of Nigeria410001NsukkaEnugu StateNigeria

objective:In our continued efforts to isolate the active immunomodulatory and antiviral constituents of Loranthus micranthus Linn parasitic on Kola acuminata,we set out to fractionate the crude aqueous methanol extract of the *** establishment of the most potent fraction(s) as well as the isolation of the pure active secondary metabolite responsible for the immune stimulatory and antiviral activities in eastern Nigeria mistletoe has become very *** will enable us prove our assumption that this particular specie is different from the european version,Viscum ***:Five solvents of varying polarity namely n-hexane,chloroform, ethylacetate,acetone and methanol were successively employed in the complete fractionation of the crude aqueous -methanol extract of eastern Nigerian mistletoe,Loranthus micranthus Linn.,harvested from Kola acuminata in that *** fractions were dried in-vacuo using a rotary evaporator maintained at a temperature of(40±5)℃.The different fractions were screened for immunomodulatory activity using a universal model:the cellular - mediated delayed type hypersensivity test in experimental *** was performed by administering two different dose levels:250 mg/kg and 500 mg/kg of each fraction against standard positive and negative control. Results:Results of the study established dose-dependent immunostimulatory(upregulatory) effects of the five fractions of the extract as the model used in the study with different percentage stimulations compared to *** the dose levels of 500 mg/kg and 250 mg/kg body weight,the percentage stimulation observed were as following:chloroform fraction 311.11%and 122.22%,ethyl acetate fraction 193.38%and 95. 56%,n-hexane 155.56%and 3.50%,acetone fraction 95.56%and 51.11%and methanol fraction 68. 89%and 24.44%***,a known potent immunostimulant,afforded a stimulation of 68. 89%at a dose of 2.5 mg/***:The study showed that the order of immunomodulatory potency

关键词： Loranlhus micranthus Mistletoe eastern Nigeria Solvent fractionation Immunomodulatory

Characterization of particle deposition during crossflow filtration as influenced by permeate flux and crossflow velocity using a microfluidic filtration system

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Frontiers of Chemical Science and engineering 2021年第3期15卷 552-561页

作者： Hongzhan Di Gregory J.o.Martin Dave e.Dunstan Department of Chemical and Biomolecular engineering University of MelbourneParkvilleVictoria 3010Australia

Particle deposition during crossflow filtration is significantly influenced by the operating conditions,in particular the permeate flux and crossflow ***,there is a lack of detailed knowledge about how deposit layer structures and distributions depend on operating *** study uses a microfluidic visualisation filtration system to examine the influence of operating conditions on the deposition process during crossflow ultrafiltration from a microscopic *** the permeate flux caused an increasing amount of deposition and a thicker deposit *** crossflow velocities reduced the extent of *** degree of deposition varied over a range of operating conditions due to the altered hydrodynamic forces exerted on the particles,which can be examined by the deposition probability according to an existing *** on this,an empirical correlation between the deposition probability and volume of deposition as a function of filtration time was developed,which gave good agreement with experimental *** effect of solution conditions was also involved in this correlation as a interaction *** could be useful for predicting the dynamic deposition process during crossflow filtration over a range of operating and solution conditions.

关键词： particle deposition crossflow filtration microfluidics confocal microscopy

Screening of ethyl acetate extract of Bridelia micrantha for hepatoprotective and anti-oxidant activities on Wistar rats

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Asian Pacific Journal of Tropical Medicine 2011年第10期4卷 796-798页

作者： Nwaehujor Chinaka o Udeh Nkeiruka e Department of Veterinary Physiology and Pharmacology University of NigeriaNsukkaEnugu StateNigeria Department of Veterinary Physiology and Pharmacology Michael Okpara University of AgricultureUmudikeAbia StateNigeria

objective:To explore the hepatoprotective and anti-oxidant activities of the methanolic leaf extract of Bridelia micrantha(***) on paracetamol induced liver damage in Wistar rats. Methods:Parameters were measured including alanine aminotransaminase(ALT),aspartate aminotransferase(AST),alkaline phosphatase(ALP),bilirubin and total *** anti-oxidant effects were studied using the 1,l-Diphenynl-2-Picrylhydrazyl(DPPH) and Ferric Reducing Antioxidant Power(FRAP) assay ***:*** extract decreased the level of AST in the rats given PCM from(129.47±0.921) IU/L to(57.78±1.71) IU/L(Power than the value for Silymarin which was(59.92±1.41) IU/*** concentration was reduced from (150.18±2.23) IU/L to(79.10±2.01) IU/L(Peduced from(49.86±0.85) IU/L to(29.64±1.53) IU/L(Potal bilirubin was reduced from(2.14±0.10 mg/dL) to(0.18±0.07) mg/dL (Pe total protein was increased from(4.26±0.30) mg/dL to(6.20±0.19) mg/dL(Poncentrations ranging from 10 - 400μg/mL of *** were assayed for antioxidant *** DPPH assay showed 98%antioxidant activity at concentration of 400μg/mL. The FRAP values were 0.016,0.39,0.455,0.601 and 1.382μM at 10.50,100,200 and 400μg/ mL ***:Results suggest that *** has hepatoprotective and anti oxidant ***,further work involving fractionation needs to done to isolate the active compound responsible for the hepatoprotective activity.

关键词： Bridelia micrantha ethyl acetate leaf extract Hepatoprotective Antioxidant

effect of Sodium oleate Concentration Variations on Froth Flotation of Manganese ore

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International Journal of Nonferrous Metallurgy 2019年第3期8卷 25-33页

作者： ogundeji Frncis oladapo alabi oladunni Department of Metallurgical and Materials engineering Federal University of Technology Akure Nigeria

each type of a manganese deposit is a problem by itself in the matter of selection of a proper method of concentration, depending on the manganese minerals and their gangue constituents. Hence, this work studied the effect of sodium oleate concentration variation on the froth flotation of manganese ore obtained from Madaka, Niger State, Nigeria. The chemical analysis of the ore shows that it contains 48.4% Mno (37.5% Mn). Peaks were identified in XRD analysis of the crude sample as that of magnosite (Mno), hausmannite (Mn3o4), spessartine and vemuculite (Mg, Fe2+, Fe3+)3[(AlSio4)o10](oH)2·4H2o. The ore was beneficiated by froth flotation using sodium oleate as collector at varied concentrations of 3 g/kg, 7 g/kg and 10 g/kg. other chemical reagents used were sodium silicate, fuel oil and calcium hydroxide as dispersant, frother and pH modifier respectively. Results obtained showed percentage metal recoveries of 9.29%, 14.30% and 19.61%, assaying 65.20%, 62.03% and 61.30% Mn respectively. This indicates that at sodium oleate concentration of 3 g/kg, high grade-concentrate can be obtained.

关键词： Manganese ore Sodium oleate Comminution Beneficiation Recovery