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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 e.f.ct 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.f.r 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 e.f.ct 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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Modeling of nonlinear envelope solitons in strongly coupled dusty plasmas:Instability and collision

作者： e.f.·梅格耶斯(e.f. Megyesy)

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Chinese Physics B 2015年第3期24卷 237-247页

作者： S.K.el-Labany e.f.el-Shamy W.f.el-Taibany N.A.Zedan Department of Physics Faculty of ScienceDamietta University Department of Physics College of ScienceKing Khalid University Department of Physics College of Science for Girls in AbhaKing Khalid University

Modeling of instability and collision of nonlinear dust-acoustic（NDA） envelope solitons in strongly coupled dusty plasmas（SCDPs） is theoretically investigated. The SCDPs consists of strongly correlated negatively variable-charged dust grains and weakly correlated Boltzmann electrons and ions. Using the derivative expansion perturbation technique, a nonlinear Schr dinger-type（NLST） equation for describing the propagation of NDA envelope solitons is derived. Moreover,the extended Poincar′e–Lighthill–Kuo（ePLK） method is employed to deduce the analytical phase shifts and the trajectories after the collision of NDA envelope solitons. In detail, the results show that both modulation instability and phase shift after collision of NDA envelope solitons will modify with the increase in the e.f.cts of the viscosity, the relaxation time, and the dust charge.f.uctuation. Crucially, the modeling of dust-acoustic envelope solitons collision, as reported here, is helpful for understanding the propagation of NDA envelope solitons in strongly coupled dusty plasmas.

关键词： dust acoustic wave envelopes modulational instability head-on collision polarization e.f.cts

High energy barriers for edge dislocation motion in body-centered cubic high entropy alloys

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npj Computational Materials 2021年第1期7卷 1017-1025页

作者： R.e.Kubilay A.Ghafarollahi f.Maresca W.A.Curtin Laboratory for Multiscale Mechanics Modeling(LAMMM) Institute of Mechanical EngineeringEPFLLausanneSwitzerland engineering and technology institute groningen faculty of science and Engineeringuniversity of groningengroningenthe netherlands

Recent theory proposes that edge dislocations in random body-centered cubic(BCC)high entropy alloys have high barriers for motion,conveying high strengths up to high ***,the energy barriers for edge motion are computed for two model alloys,NbTaV and MoNbTaW as represented by interatomic potentials,using the Nudged elastic Band method and compared to theoretical *** average magnitude of the barriers and the average spacing of the barriers along the glide direction agree well with the analytical theory,with no adjustable *** evolution of the barriers versus applied stress is modeled,and the mean strength is in reasonable agreement with the predicted zero-temperature *** findings validate the analytic theory.A reduced analytic model based on solute misfit volumes is then applied to Hf-Mo-Nb-Ta-Ti-Zr and Mo-Nb-Ta-Ti-VW alloys,rationalizing the observed significant strength increases at room temperature and 1000℃upon addition of solutes with large misfit into a base *** analytic theory for edge motion is thus a powe.f.l validated tool for guiding alloy selection.

关键词： alloys strength alloy

VARIATION Of PHYSICO-CHeMICAL PROPeRTIeS Of RADIATION CROSSLINKeD RUBBeR WITH STORAGe TIMe

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Chinese Journal of Polymer Science 2005年第5期23卷 497-501页

作者： N.C.Dafader M.e.Haque.f.Akhtar Nuclear and Radiation Chemistry Division

The e.f.ct of storage on physico-chemical properties of non-irradiated natural rubber and radiation vulcanized natural rubber （RVNR） were evaluated. The rubber films were stored under two different conditions, namely in open air and sealed polyethylene bags. The antioxidant, tris（nonylated phenyl） phosphite （TNPP） was used for preventing degradation of RVNR films. Gel content, cross-link density, tensile strength at break and 500% elongation of rubber films were measured. The results show that the retention （%） of tensile properties of rubber films with TNPP is higher than that of rubber films without antioxidants. The rubber films stored in polyethylene bags also show better retention of tensile properties than those of rubber films stored in open air.

关键词： Storage Radiation Tensile Properties Antioxidant.

STUDY ON THe PROPeRTIeS Of BLeND Of NATURAL RUBBeR LATeX/MeTHYL MeTHACRYLATe GRAfTeD RUBBeR LATeX BY GAMMA RADIATION

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Chinese Journal of Polymer Science 2007年第5期25卷 519-523页

作者： N.C. Dafader M.e. Haque.f. Akhtar Nuclear and Radiation Chemistry Division Institute of Nuclear Science ＆ Technology Bangladesh Atomic Energy Commission P. O. Box 3787 Dhaka Bangladesh

Natural rubber latex （NRL） and methyl methacrylate （MMA） grafted rubber latex were blended in different ratios and irradiated at various absorbed doses by gamma rays from Co-60 source at room temperature. The tensile properties, swelling ratio and permanent set were measured. The maximum tensile strength and modulus at 500% elongation were obtained at an absorbed dose of 8 kGy. Modulus increases from 6.99 MPa to 9.87 MPa for an increase in proportion of MMA grafted rubber from 40% to 60% in the blend at similar absorbed dose. elongation at break and swelling ratio decrease with increasing absorbed dose as well as the MMA grafted rubber content in the blends. The decreasing trend of permanent set is high up to 5 kGy absorbed dose, and beyond that dose, it becomes almost flat.

关键词： Natural rubber latex MMA grafted rubber latex Blend rubber Irradiation Cross-link.

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计算机在物理教学中不同用途的比较

物理教学 1987年第1期 1-3页

作者： e.f.泰勒沈念慈美国麻省理工学院物理系

我热爱物理学有二个理由。首先,物理学把非常简单的系统研究得很深入。其次,物理学描述相反的方面,既讨论我们周围的日常物理世界,也研究远离一般经验的世界,如极快世界(相对论)、极大世界(宇宙论)和极小世界(量子物理学)。

关键词：计算机模拟工具演示程序程序员物理教学

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Study of Transition from Laminar to Turbulent Boundary Layer on a Tilted flat Plate Using Heat Transfer Measurements

作者： e.f.·梅格耶斯(e.f. Megyesy)

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Journal of Thermal Science 2007年第2期16卷 186-191页

作者： e.Sanz C.Nicot R.Point f.Plaza Laboratoire de Mécanique des fluides et Acoustique LMFA(ECL-UCB-INSA Lyon-CNRS)36Avenue Guy de Collongue69134 Ecully.France.

The boundary layer transition over a flat tilted plate has been studied by means of heat transfer measurements. A heat flux sensor has been developed, in order to measure the e.f.ciency of convective heat transfer for various types of surfaces or flows. Its operation at constant temperature allows direct and fast measurements of heat flux. The present paper reports the development of the sensor and presents its application to the study of transition in a boundary layer depending on the angle of incidence of the external flow. An exponential relationship between critical Reynolds number and pressure gradient parameter has been found.

关键词： convective heat flux boundary layer transition pressure gradient.