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Daily variation of radon gas and its short-lived progeny concentration near ground level and estimation of aerosol residence time

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Chinese Physics B 2016年第5期25卷 111-118页

作者： m mohery A m Abdallah A Ali S S Baz Physics Department Faculty of Science University of Jeddah Physics Department Faculty of Science Sohag University Astronomy Department Faculty of Science King Abdulaziz University Astronomy Department Faculty of Science Cairo University Physics Department Girls Faculty of Science King Abdulaziz University

Atmospheric concentrations of radon（^（222）Rn） gas and its short-lived progenies^（218）Po,^（214）Pb, and^（214）Po were continuously monitored every four hours at the ground level in Jeddah city, Kingdom of Saudi Arabia. The measurements were performed three times every week, starting from November 2014 to October 2015. A method of electrostatic precipitation of positively charged^（218）Po and ^（214）Po by a positive voltage was applied for determining^（222）Rn gas concentration. The short-lived^（222）Rn progeny concentration was determined by using a filter holder connected with the alpha-spectrometric technique. The meteorological parameters（relative air humidity, air temperature, and wind speed） were determined during the measurements of^（222）Rn and its progeny concentrations.^（222）Rn gas as well as its short-lived progeny concentration display a daily and seasonal variation with high values in the night and early morning hours as compared to low values at noon and in the afternoon. The observed monthly atmospheric concentrations showed a seasonal trend with the highest values in the autumn/winter season and the lowest values in the spring/summer season. moreover, and in parallel with alphaspectrometric measurements, a single filter-holder was used to collect air samples. The deposited activities of^（214）Pb and the long-lived^（222）Rn daughter ^（210）Pb on the filter were measured with the gamma spectrometric technique. The measured activity concentrations of^（214）Pb by both techniques were found to be relatively equal largely. The highest mean seasonally activity concentrations of ^（210）Pb were observed in the autumn/winter season while the lowest mean were observed in the spring/summer season. The mean residence time（mRT） of aerosol particles in the atmospheric air could be estimated from the activity ratios of ^（210）Pb/^（214）Pb.

关键词： daily variation radon progeny concentration meteorological variables

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The electrical impedance, AC conductivity and dielectric properties of phenol red compound investigated and modeled by an artificial neural network

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Communications in Theoretical Physics 2020年第10期72卷 139-148页

作者： H A m Ali D m Habashy Physics Department Faculty of EducationAin Shams UniversityRoxyCairo 11757Egypt

The impedance spectroscopy,electrical conductivity and electric modulus of bulk phenol red were measured,as a function of both frequency and *** neural networks(ANNs)were used for modeling its electrical *** two parts(real and imaginary)of its complex impedance(Z^*)were analyzed and the activation energy related to the electrical relaxation process was *** curves were plotted showing semicircles for the different *** AC electrical conductivity follows a power lawσac(ω)αω^η.The maximum barrier height Bm was derived for specific temperatures.A plausible mechanism for the AC conduction of bulk phenol red was deduced from the temperature reliance of the frequency *** dielectric data was analyzed using electric modulus as a *** addition,ANNs were used to model the impedance parts and the total electrical *** runs were tried,to obtain the best *** training and prediction results were compared to the equivalent experimental results,with a good match *** equation describing the experimental results was obtained mathematically,based on the use of *** outputs demonstrated that ANNs are an admirable tool for modeling experimental results.

关键词： phenol red impedance spectroscopy electric modulus neural network

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OPTImIZATION OF THE SYNTHESIS OF ACRYLAmIDE HYDROGEL BY γ-RAY IRRADIATION

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Chinese Journal of Polymer Science 2004年第3期22卷 253-258页

作者： m.A. Chowdhury m.m. Alam m.F. mina F. Akhtar S.E. Kabir Department of Chemistry Faculty of Science Jahangir Nagar University Dhaka BangladeshNRCD INST AERE GPO Box-3787 Dhaka Bangladesh NRCD INST AERE GPO Box-3787 Dhaka Bangladesh NRCD INST AERE GPO Box-3787 Dhaka Bangladesh Department of Chemistry Faculty of Science Jahangir Nagar University Dhaka Bangladesh

Hydrogels have been synthesized from 10%, 20%, 30%, 40%, 50% and 60% aqueous solutions of acrylamide monomer by gamma radiation employing doses in the range of 0.2-30 kGy from a Co-60 source. The effect of solution concentration, γ-ray dose, pH and time was studied in order to observe the optimizing conditions in the characterization of hydrogels. Gel fraction increases with dose for all concentrations indicating hundred-percentage conversion of gel at doses 5 kGy for homogenous solutions in the range of 20%-50% concentration. On the other hand, 10% solution provides conversion less than 86% even at 30 kGy, whereas 60% monomer makes an inhomogeneous solution which stile gives about 100% gel fraction. Swelling of hydrogels under water with respect to time varies with both the doses and concentrations due to the change of crosslinking density in the gels. The maximum volume change of hydrogels during swelling and water desorption mainly occurs within 24 h. Swelling is also enhanced with the rise of pH due to change of ionic content of the solvent. Considering the amount of gel fraction and the properties of hydrogel, the samples prepared from 20% solution at 5 kGy show better results. moreover, the effect of bacteria on hydrogel was found to be nil, suggesting a prohibition of growth of microorganism in it.

关键词： Hydrogel Acrylamide γ-radiation Swelling microorganism

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Role of ZnO-CeO_2 Nanostructures as a Photo-catalyst and Chemi-sensor

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Journal of materials Science & Technology 2011年第7期27卷 594-600页

作者： m. Faisal Sher Bahadar Khan mohammed m. Rahman Aslam Jamal Kalsoom Akhtar m.m. Abdullah Centre for Advanced materials and Nano-Engineering (CAmNE) and Department of Chemistry Faculty of Sciences and Arts Najran UniversityNajran 11001 Kingdom of Saudi Arabia Division of Nano Sciences and Department of Chemistry Ewha Womans UniversitySeoul 120-750 Korea

ZnO-CeO2 nanostructures were synthesized by simple and effcient low temperature method. The structure and morphology of the ZnO-CeO2 nanostructures were characterized by X-ray powder diffraction （XRD） and field emission scanning electron microscopy （FESEm）, which revealed elongated shaped CeO2 nanoparticles with diameters of 40–90 nm distributed on the surface of elongated ZnO nanostructures with diameters of 50–200 nm （edge–centre）. Further the structure of the synthesized ZnO-CeO2 nanostructure was supported by Raman spectra and Fourier transform infrared spectroscopy （FTIR）. UV-vis absorption spectrum was used to confirm the optical properties of the CeO2 doped ZnO nanostructures. Photo-catalytic activity of CeO2 doped ZnO nanostructure was evaluated by degradation of acridine orange and methylene blue which degraded 84.55% and 48.65% in 170 min, respectively. ZnO-CeO2 nanostructures also showed good sensitivity （0.8331 μA·cm-2·（mol/l）-1） in short response time （10 s） by applying to chemical sensing using ethanol as a target compound by I-V technique. These degradation and chemical sensing properties of ZnO-CeO2 nanostructures are of great importance for the application of ZnO-CeO2 system as a photo-catalyst and chemical sensor.

关键词： ZnO-CeO2 nanostructures Structural properties Optical properties Photocatalytic activity Ethanol sensing

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melting phenomenon in magneto hydro-dynamics steady flow and heat transfer over a moving surface in the presence of thermal radiation

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Chinese Physics B 2013年第3期22卷 57-62页

作者： Reda G.Abdel-Rahman m.m.Khader Ahmed m.megahed Department of mathematics Faculty of ScienceBenha University

The Lie group method is applied to present an analysis of the magneto hydro-dynamics（mHD） steady laminar flow and the heat transfer from a warm laminar liquid flow to a melting moving surface in the presence of thermal *** using the Lie group method,we have presented the transformation groups for the problem apart from the scaling *** application of this method reduces the partial differential equations（PDEs） with their boundary conditions governing the flow and heat transfer to a system of nonlinear ordinary differential equations（ODEs） with appropriate boundary *** resulting nonlinear system of ODEs is solved numerically using the implicit finite difference method（FDm）.The local skin-friction coefficients and the local Nusselt numbers for different physical parameters are presented in a table.

关键词： Lie group method magneto hydro-dynamics melting phenomenon Newtonian fluid radiation

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Effects of QCD Vacuum and the Instanton Induced-Contributions to the Nucleon Structure Functions

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Communications in Theoretical Physics 2013年第2期59卷 179-186页

作者： A. mirjalili m. Dehghani m.m. Yazdanpanah Physics Department Yazd University 89195-741 Yazd Iran Faculty of Physics Shahid Bahonar University of Kerman Kerman Iran

The instanton induced cross section in deep inelastic kinematics is a subject which people are tendentious to investigate it. Instanton induced contributions are well defined for the nucleon structure function. The non-perturbative contribution to the quark distributions of structure function, F2（x, Q2）, is considered within an instanton model for the QCD vacuum. We find that the structure function may possess numerically large non-perterbative contributions which are related to the violation of chirality and correspond to the correction of parton distribution of the leading twist. It is shown that the instantons give a negative contribution to the structure function at the NLO approximation. A comparison between our results, considering instantaon effect, and the case when we do not take this effect is done. Taking into account the instanton size, p, via the modified running coupling constant we get to a good agreement between our results at the NLO and NNLO approximations and the available experimental data, specially at the low values of the Bjorken variable x 〈 0.1 which confirms the validity of our calculations.

关键词： effective Lagrangian instanton effects quark chirality flipping nucleon structure function

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Comprehensive investigation of stress intensity factors in rotating disks containing three-dimensional semi-elliptical cracks

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Applied mathematics and mechanics(English Edition) 2017年第11期38卷 1565-1578页

作者： m.FAKOOR S.m.N.GHOREISHI Faculty of New Sciences and Technologies University of Tehran Tehran 14395-1561 Iran

Initiation and propagation of cracks in rotating disks may cause catastrophic failures. Therefore, determination of fracture parameters under different working con- ditions is an essential issue. In this paper, a comprehensive study of stress intensity factors （SIFs） in rotating disks containing three-dimensional （3D） semi-elliptical cracks subjected to different working conditions is carried out. The effects of mechanical prop- erties, rotational velocity, and orientation of cracks on SIFs in rotating disks under cen- trifugal loading are investigated. Also, the effects of using composite patches to reduce SIFs in rotating disks are studied. The effects of patching design variables such as mechanical properties, thickness, and ply angle are investigated separately. The modeling and analytical procedure are verified in comparison with previously reported results in the literature.

关键词： stress intensity factor (SIF) semi-elliptical crack rotating disk finite ele-ment analysis (FEA)

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Eccentricity and thermoviscous effects on ultrasonic scattering from a liquid-coated fluid cylinder

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第1期9卷 65-78页

作者： Seyyed m. HASHEmINEJAD m. A. ALIBAKHSHI Acoustics Research Lab. Department of Mechanical Engineering Iran University of Science and Technology Narmak Tehran 16844 Iran

Calculation of the scattered field of the eccentric scatterers is an old problem with numerous applications. This study considers the interaction of a plane compressional sound wave with a liquid-encapsulated thermoviscous fluid cylinder submerged in an unbounded viscous thermally conducting medium. The translational addition theorem for cylindrical wave functions, the appropriate wave field expansions and the pertinent boundary conditions are employed to develop a closed-form solution in the form of infinite series. The analytical results are illustrated with a numerical example in which the compound cylinder is insonified by a plane sound wave at selected angles of incidence in a wide range of dimensionless frequencies. The backscattered far-field acoustic pressure amplitude and the spatial distribution of the total acoustic pressure in the vicinity of the cylinder are evaluated and discussed for representative values of the parameters characterizing the system. The effects of incident wave frequency, angle of incidence, fluid thermoviscosity, core eccentricity and size are thoroughly examined. Limiting case involving an ideal com- pressible liquid-coated cylinder is considered and fair agreement with a well-known solution is established.

关键词： Thremoviscous effects Eccentric fluid cylinder Acoustic scattering

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Density functional theory study of structural,electronic,and thermal properties of Pt,Pd,Rh,Ir,Os and PtPdX(X=Ir,Os,and Rh)alloys

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Chinese Physics B 2016年第3期25卷 298-306页

作者： Shabbir Ahmed muhammad Zafar m Shakilt m A Choudhary Simulation Laboratory Department of Physicsthe Islamia University of BahawalpurBahawalpur 63100Pakistan o Department of Physics Hafiz Hayat CampusUniversity of GujratGujrat 50700Pakistan

The structural, electronic, mechanical, and thermal properties of Pt, Pd, Rh, Ir, Os metals and their alloys PtPdX （X = Ir, Os and Rh） are studied systematically using ab initio density functional theory. The groundstate properties such as lattice constant and bulk modulus are calculated to find the equilibrium atomic position for stable alloys. The electronic band structure and density of states are calculated to study the electronic behavior of metals on making their alloys. The electronic properties substantiate the metallic behavior for all studied materials. The firstprinciples density functional perturbation theory as implemented in quasi-harmonic approximation is used for the calculations of thermal properties. We have calculated the thermal properties such as the Debye temperature, vibrational energy, entropy and constant-volume specific heat. The calculated properties are compared with the previously reported experimental and theoretical data for metals and are found to be in good agreement. Calculated results for alloys could not be compared because there is no data available in the literature with such alloy composition.

关键词： electronic structural and thermal properties platinum group metals

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Analytical Determination of Collisionless Sheath Properties for Triple Frequency Capacitively Coupled Plasma

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Plasma Science and Technology 2015年第2期17卷 141-146页

作者： m.T.RAHmAN m.N.A.DEWAN Department of Electrical and Electronic Engineering Bangladesh University of Engineering and Technology

A triple frequency capacitively coupled plasma （TF-CCP） has been considered to investigate the behavior of the sheath parameters. A self-consistent time-independent collisionless model has been developed. The sheath width and potential are calculated using the present model and compared with those calculated using a single-frequency （SF）, a dual-frequency （DF） and a triple-frequency （TF） model for time independent collisionless cases. The sheath motion and sheath potential are found to be larger compared with those of SF and DF CCPs for an inhomogeneous sheath, and that of TF CCP for a homogeneous sheath. The effects of the source parameters, i.e., current magnitudes, frequencies and phase difference, on the sheath parameters are investigated. The sheath parameters show higher values at higher source currents whereas they decrease with the increase of excitation frequencies. It has also been found that, by the proper choice of source frequencies and phase differences, it is possible to adjust the energy of ions when they hit the electrode.

关键词： capacitively coupled plasma collisionless sheath triple frequency sheath parameters

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