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Oblique collisional effects of dust acoustic waves in unmagnetized dusty plasma

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Chinese Physics B 2020年第6期29卷 304-313页

作者： m S Alam m R Talukder Department of mathematics Chittagong University of Engineering and TechnologyChittagong-4349Bangladesh Plasma Science and Technology Laboratory Department of Electrical and Electronic EngineeringUniversity of RajshahiRajshahi-6205Bangladesh

Effects of oblique collisions of the dust acoustic(DA)waves in dusty plasma are studied by considering unmagnetized fully ionized *** plasma consists of inertial warm negatively charged massive dusts,positively charged dusts,superthermal kappa distributed electrons,and isothermal *** extended Poincaré–Lighthill–Kuo(e PLK)method is employed for the drivation of two-sided Korteweg–de Vries(KdV)equations(KdVEs).The Kd V soliton solutions are derived by using the hyperbolic secant *** effects of superthermality index of electrons,temperature ratio of isothermal ion to electron,and the density ratio of isothermal ions to negatively charged massive dusts on nonlinear coefficients are *** effects of oblique collision on amplitude,phase shift,and potential profile of right traveling solitons of DA waves are also *** study reveals that the new nonlinear wave structures are produced in the colliding region due to head-on collision of the two counter propagating DA *** nonlinearity is found to decrease with the increasing density ratio of ion to negative dust in the critical *** phase shifts decrease(increase)with increasing the temperature ratio of ion to electron(κe).The hump(compressive,κeκec)solitons are produced depending on the angle(θ)of oblique collision between the two waves.

关键词： ion acoustic wave dusty plasma kappa distribution ePLK method hyperbolic secant method

Serological surveillance for SARS-CoV-2 antibodies among students,faculty and staff within a large university system during the pandemic

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World Journal of Virology 2025年第1期14卷 99-107页

作者： marcos G Pinheiro Gabriela G O Alves maria Eduarda R Conde Sofia L Costa Regina C S Sant’Anna Isa m F Antunes mônica C Carneiro Fabio S Ronzei Julia C Scaffo Felipe R Pinheiro Lialyz S Andre Helvecio C Povoa Valéria T Baltar Fabíola Giordani Eduarda S Hemerly Gisele C Alexandre Karla C de Paula márcio Watanabe Antonio Claudio L da Nóbrega Jackeline Christiane P Lobato Fabio Aguiar-Alves Laboratory of molecular Epidemiology and Biotechnology Rodolpho Albino University LaboratoryFluminense Federal UniversityNiterói 24241000Rio de JaneiroBrazil Estácio de SáUniversity Nova Friburgo 28611135Rio de JaneiroBrazil Pathology Program Medicine schoolFluminense Federal UniversityNiterói 24070090Rio de JaneiroBrazil Department of Pharmaceutical Sciences Lloyd L.Gregory School of PharmacyPalm Beach Atlantic UniversityWest Palm BeachFL 33401United States Health Institute of Nova Friburgo Fluminense Federal UniversityNova Friburgo 28613001Rio de JaneiroBrazil Department of Epidemiology and Biostatistics Institute of Collective Health(ISC)Fluminense Federal UniversityNiterói 24033900Rio de JaneiroBrazil Institute of Physical Education Fluminense Federal UniversityNiterói 24020005Rio de JaneiroBrazil Department of Statistics Fluminense Federal UniversityNiterói 24210200Rio de JaneiroBrazil Department of Physiology and Pharmacology Fluminense Federal UniversityNiterói 24210130Rio de JaneiroBrazil

BACKGROUND At the end of December 2019,the world faced severe acute respiratory syndrome-coronavirus 2(SARS-CoV-2),which led to the outbreak of coronavirus disease 2019(COVID-19),associated with respiratory *** virus has shown significant challenges,especially for senior citizens,patients with other underlying illnesses,or those with a sedentary *** tests conducted early on have helped identify how the virus is transmitted and how to curb its *** study hypothesis was that the rapid serological test for SARS-CoV-2 antibodies could indicate the immunoreactive profile during the COVID-19 pandemic in a university *** To conduct active surveillance for serological expression of anti-SARS-CoV-2 antibodies in individuals within a university setting during the COVID-19 *** This sectional study by convenience sampling was conducted in a large university in Niteroi-RJ,Brazil,from march 2021 to July *** study population consisted of students,faculty,and administrative staff employed by the university.A total of 3433 faculty members,60703 students,and 3812 administrative staff were invited to *** were gathered through rapid serological tests to detect immunoglobulin(Ig)m and IgG against ***χ²or Fisher's exact test was used to conduct statistical analysis.A 0.20 significance level was adopted for variable selection in a multiple logistic regression model to evaluate *** A total of 1648 individuals were enrolled in the *** proportion of COVID-19 positivity was 164/1648(9.8%).The adjusted logistic model indicate a positive association between the expression of Igm or IgG and age[odds ratio(OR)=1.16,95%CI:1.02-1.31](P<0.0024),individuals who had been in contact with a COVID-19-positive case(OR=3.49,95%CI:2.34-5.37)(P<0.001),those who had received the COVID-19 vaccine(OR=2.33,95%CI:1.61-3.35)(P<0.001)and social isolation(OR=0.59,95%CI:0.41-0.84)(P<0.004).The likelihood of sho

关键词： Serological surveillance SARS-CoV-2 antibodies COVID-19 Serological rapid test Risk factors for COVID-19

Adsorption properties of Rosmarinus officinalis oil as green corrosion inhibitors on C38 steel in 0.5 m H_2SO_4

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Acta metallurgica Sinica(English Letters) 2010年第1期23卷 13-20页

作者： E.El Ouariachi J.Paolini m.Bouklah A.Elidrissi A.Bouyanzer B.Hammouti J-m.Desjobert J.Costa Laboratoire de Chimie Appliqu'ee et Environnement Facult'e des SciencesUniversit'e Mohamed PremierBP71760000 OujdaMorocco UmR CNRS 6134 Laboratoire de Chimie des Produits NaturelsUniversit'e de CorseFrance

Rosmarinus officinalis essential oil obtained by hydrodistillation was tested as corrosion inhibitor of steel in 0.5 m H2SO4 using weight loss measurements, and electrochemical .polarisation methods. Results obtained indicate that the corrosion rate is reduced and R. officinalis oil adsorbs on the metal surface and then inhibits corrosion process. Its inhibition efficiency increases with oil increasing content to reach 61% at 1 g/L. Polarisation curves indicate that RO acts as a cathodic inhibitor. The inhibition efficiency of naturally oil remains slightly constant with the rise of temperature. Chemical analysis of R. officinalis essential oil was carried out using capillary GC and GC/mS. The oil composition was characterized by high amount of oxygenated monoterpene （77%） with 1,8-cineol （52.1%） as main component. Discussion of adsorption was investigated on the the isotherm adsorption of essential oil on basis of essential oil composition. Finally the steel has been also reported.

关键词： Rosmarinus officinalis oil Adsorption Corrosion Inhibition Steel 1,8-cineol

Frequency-dependent viscoelasticity effects on the wave attenuation performance of multi-layered periodic foundations

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Applied mathematics and mechanics(English Edition) 2024年第3期45卷 407-424页

作者： m.SAFI m.VAKILIFARD m.J.mAHmOODI Faculty of Civil Water&Environmental EngineeringShahid Beheshti UniversityTehran ***Iran Faculty of mechanical and Energy Engineering Shahid Beheshti UniversityTehran ***Iran

In this paper,layered periodic foundations(LPFs)are numerically examined for their responses to longitudinal and transverse modes in the time and frequency *** different unit-cells,i.e.,2-layer,4-layer,and 6-layer unit-cells,comprising concrete/rubber,concrete/rubber/steel/rubber,and concrete/rubber/steel/rubber/lead/rubber materials,respectively,are taken into ***,the viscoelasticity behavior of the rubber is modeled with two factors,i.e.,a frequency-independent(FI)loss factor and a linear frequency-dependent(FD)loss *** the extraction of the complex dispersion curves and the identification of the band gaps(BGs),the simulations of wave transmission in the time and frequency domains are performed using the COmSOL *** parametric studies evaluate the effects of the rubber viscoelasticity models on the dispersion curves and the wave transmission for the longitudinal and transverse *** results show that considering the rubber viscoelasticity enhances the wave attenuation ***,the transverse-mode damping is more sensitive to the viscoelasticity model than its longitudinal *** 6-layer unit-cell LPF exhibits the lowest BG,ranging from 4.8 Hz to 6.5 Hz.

关键词： layered metamaterial periodic foundation complex dispersion curve wave transmission diagram

Dirac R-matrix calculations of photoionization cross sections of Ni Ⅻ and atomic structure data of Ni 

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Chinese Physics B 2017年第2期26卷 127-140页

作者： R T Nazirt m A Bari m Bilal S Sardar m H Nasim m Salahuddin Department of Physics and Applied mathematics Pakistan Institute of Engineering and Applied Sciences Islamabad 45650 Pakista

We performed R-matrix calculations for photoionization cross sections of the two ground state configuration 3s^23p^5（~2P_（3/2,1/2）~o） levels and 12 excited states of Ni Ⅻ using relativistic Dirac Atomic R-matrix Codes（DARC） across the photon energy range between the ionizations thresholds of the corresponding states and well above the thresholds of the last level of the Ni XIII target ion. Generally, a good agreement is obtained between our results and the earlier theoretical photoionization cross sections. moreover, we have used two independent fully relativistic GRASP and FAC codes to calculate fine-structure energy levels, wavelengths, oscillator strengths, transitions rates among the lowest 48 levels belonging to the configuration（3s^23p^4, 3s3p^5, 3p^6, 3s^23p^33d） in Ni XIII. Additionally, radiative lifetimes of all the excited states of Ni XIII are presented. Our results of the atomic structure of Ni XIII show good agreement with other theoretical and experimental results available in the literature. A good agreement is found between our calculated lifetimes and the experimental *** present results are useful for plasma diagnostic of fusion and astrophysical plasmas.

关键词： photoionization cross sections energy levels wavelengths lifetimes

Complexity of charged anisotropic spherically symmetric fluids in f(G)gravity

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Communications in Theoretical Physics 2023年第3期75卷 91-104页

作者： Z Yousaf m Z Bhatti m m m Nasir Department of mathematics University of the PunjabQuaid-i-Azam CampusLahore-54590Pakistan

The previous ideology of complexity factor for the dynamical spheres[Herrera et al 2018,***.D,98,104059]is extended for the influence of charge.A dynamical spherically symmetric non-dissipative and dissipative self-gravitating structure is examined in the presence of maxwell f(G)gravity to examine the complexity *** pattern of evolution is studied with the minimal complexity *** complexity factor remains the same for the structure of fluid distribution,while we examine homologous constraints for the most basic evolution *** calculate the structure scalars which play an important role in order to understand the fundamental properties of the *** fluid is geodesic as well as shearing for the dissipative case and there is a large number of *** the non-dissipative fluid distribution,a shear-free,homogeneous and isotropic,geodesic fluid correlates with the evolving homologous and vanishing complexity *** implication of the condition of vanishing complexity factor and stability are discussed at the end.

关键词： gravitation anisotropy complexity hydrodynamics

Non-Newtonian effect on natural convection flow over cylinder of elliptic cross section

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Applied mathematics and mechanics(English Edition) 2020年第2期41卷 361-382页

作者： P.NAG m.m.mOLLA m.A.HOSSAIN Department of mathematics and Physics North South UniversityDhaka 1229Bangladesh Center for Applied Scientific Computing(CASC) North South UniversityDhaka 1229Bangladesh Department of mathematics University of DhakaDhaka 1000Bangladesh

The non-Newtonian effect in the boundary layer flow over a horizontal elliptical cylinder is investigated numerically. A modified power-law viscosity model is used to correlate the non-Newtonian characteristics of the fluid flow. For natural convectionflows, the surface of the cylinder is maintained by the uniform surface temperature(UST)or the uniform heat flux(UHF) condition. The governing equations corresponding to theflow are first transformed into a dimensionless non-similar form using suitable transformations. The resulting equations are solved numerically by an efficient finite difference scheme. The numerical results are presented for the skin friction coefficient and the local Nusselt number with the eccentric angle for different values of the power-law index n. The local skin friction coefficient and the local Nusselt number are found to be higher and lower, respectively, for the shear thickening fluids(n > 1) than the other fluids(n≤1).The effects of different elliptical configurations on the average Nusselt number are also presented and discussed for both conditions of the surface temperature.

关键词： non-Newtonian fluid free convection boundary layer elliptical cylinder

Adsorption isotherm and inhibition effect of a synthesized di-(m-Formylphenol)-1,2-cyclohexandiimine on corrosion of steel X52 in HCl solution

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Journal of Central South University 2016年第2期23卷 249-257页

作者： A.karimi I.Danaee H.Eskandari m.RashvanAvei Abadan Faculty of Petroleum Engineering Petroleum University of Technology Department of Chemistry K.N.Toosi University of Technology

The potential of di-(m-Formylphenol)-1,2-cyclohexandiimine as an environmentally friendly corrosion inhibitor for steel was investigated in 1 mol/L HCl using potentiodynamic polarization, electrochemical impedance spectroscopy and chronoamperometry measurements. All electrochemical measurements suggest that this compound is an excellent corrosion inhibitor for mild steel and the inhibition efficiency increases with the increase in inhibitor concentration. The effect of temperature on the corrosion behavior of mild steel with the addition of the Schiff base was studied in the temperature range from 25 °C to 65 °C. It is found that the adsorption of this inhibitor follows the Langmuir adsorption isotherms. The value of activation energy and the thermodynamic parameters such as ΔHads, ΔSads, Kads and ΔGads were calculated by the corrosion currents at different temperatures using the adsorption isotherm. The morphology of mild steel surface in the absence and presence of inhibitor was examined by scanning electron microscopy(SEm) images.

关键词： corrosion inhibitor Schiffbase adsorption Langmuir adsorption isotherm

Quantitative analysis of saindha salt using laser induced breakdown spectroscopy and cross-validation with ICP-mS

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Plasma Science and Technology 2020年第7期22卷 51-58页

作者： m QASIm m ANWAR-UL-HAQ m SHER AFGAN S U HAQ m A BAIG Department of Physics University of SargodhaSargodha 40100Pakistan Department of Energy&Power Engineering Tsinghua-BP Clean Energy CenterTsinghua UniversityBeijing 100084People’s Republic of China National Institute of Lasers and Optronics(NILOP) NiloreIslamabad 45650Pakistan National Center for Physics Quaid-i-Azam University CampusIslamabad 45320Pakistan

Saindha salt is considered to be more advantageous than the other edible salts for the patients suffering from diabetes,blood pressure and kidney *** explore the constituent elements of this salt,laser induced breakdown spectroscopy(LIBS) has been exploited for its qualitative and quantitative *** third harmonic(355 nm) of a Q-switched Nd:YAG laser has been used to produce the saindha salt plasma and the time integrated optical emission spectra were registered using a set of six miniature spectrometers covering the spectral range of 230-805 *** spectroscopic analysis of the emission spectra predominately revealed numerous neutral or singly ionized emission lines of Ca,mg,Na,K,Fe,Sr,Si,Li and *** laser produced plasma was characterized by calculating the electron temperature from the Boltzmann plots and the electron number density from the Stark broadened line profile as a function of laser irradiance and distance from the target *** relative concentration of the constituent elements was extracted by the integrated line intensities of the strongest spectral line of each element using the self-calibration-LIBS(SC-LIBS) and one-line calibration free-LIBS(OLCF-LIBS) *** cross-validation,the LIBS results have been compared with that obtained from the inductively coupled plasma-mass spectroscopy(ICP-mS) showing good agreement.

关键词： elemental analysis CF-LIBS plasma parameters