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SWELLING BEHAVIOR Of ACRYLAmIDE HYDROGEL IN DIffERENT SOLVENTS AND pHs

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Chinese Journal of Polymer Science 2005年第3期23卷 269-274页

作者： m.f.mina m.m.Alam Institute of Nuclear Science and Technology Atomic Energy Research EstablishmentGPO Box-3787Dhaka-1000BangladeshInstitute of Nuclear Science and TechnologyAtomic Energy Research EstablishmentGPO Box-3787Dhaka-1000Bangladesh

Swelling property of acrylamide hydrogels,prepared from aqueous solutions of acrylamide monomer havingconcentrations in the range of 10-60 wt% by ray irradiation method using a Co-60 gamma radiation source at dosesranging 1-30.0 kGy,has been investigated under various swelling *** swelling media were basically solvents(solutions),produced by dissolving methanol,ethanol,glucose,sucrose,sodium chloride and sodium persulfate individuallywith distilled water,and solutions prepared with pHs=3,7 and *** investigation was performed in order to observe theeffect of these solvents and pHs as well as the influence of monomer concentrations,radiation doses and times on swellingbehavior of *** values were found higher for hydrogels prepared with lower monomer concentrations(ca.20 wt%)and radiation doses(ca.5 kGy)and showed a leveling off tendency within 24 *** glucose solvent and the buffersolution of pH=10 revealed significant increase of swelling of hydrogels as compared to other *** areexplained based on crosslinking density in hydrogel,polymer-solvent/polymer-polymer interactions in solutions,permeability of molecules in solutions and ionization capacity of hydrogel in pH.

关键词： Acrylamide Hydrogel Co-60 gamma radiation source Swelling.

Photometric Investigation of Contact Binary DY Cet Based on TESS Data

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Research in Astronomy and Astrophysics 2022年第5期22卷 121-128页

作者： m.f.Yildirim Canakkale Onsekiz mart University Astrophysics Research Center and Ulupinar Observatory17020CanakkaleTurkey Canakkale Onsekiz mart University Department of Electricity and EnergyCan Vocational School17400CanakkaleTurkey

We present a photometric analysis of the Transiting Exoplanet Survey Satellite(TESS)light curve of contact binary system DY Cet and the behavior of its orbital period *** light curve and published radial velocity data analysis was performed using the Wilson-Devinney *** a result of simultaneous analysis of the light curve with radial velocity data,the masses and radii of the system’s components were determined as m_(1)=1.55±0.02 m_(⊙),m_(2)=0.55±0.01 m_(⊙) and R_(1)=1.51±0.02 R_(⊙),R_(2)=0.95±0.02 R_(⊙),*** degree of contact(f)and mass ratio(q)of the system were determined as 23%and 0.355±0.012,*** period analysis of DY Cet was conducted for the first time in this *** was observed that the orbital period has a sinusoidal change with decreasing *** explain the orbital period change,mass transfer between components is proposed with the assumption of conservative mass,and the transfer rate was calculated to be dm/dt=1.1×10^(-7) m_(⊙)yr^(-1).A possible third component is suggested for explaining the sinusoidal change,and the mass of the unseen component was determined as 0.13 m_(⊙).The age of the DY Cet system was estimated as 3.77 Gyr.

关键词： stars eclipsing binary stars-stars fundamental parameters of stars- stars individual (DY Cet)

Control and vibration analyses of a sandwich doubly curved micro-composite shell with honeycomb,truss,and corrugated cores based on the fourth-order shear deformation theory

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Applied mathematics and mechanics(English Edition) 2024年第10期45卷 1773-1790页

作者： f.SHIRDELAN m.mOHAmmADImEHR f.BARGOZINI Department of Solid mechanics Faculty of Mechanical EngineeringUniversity of KashanKashan 87317-53153Iran

Curved shells are increasingly utilized in applied engineering due to their shared characteristics with other sandwich structures,flexibility,and attractive ***,the inability of controlling and regulating vibrations and destroying them afterward is a challenge to *** this paper,the curve shell equations and a linear quadratic regulator are adopted for the state feedback design to manage the structure vibrations in state space forms.A five-layer sandwich doubly curved micro-composite shell,comprising two piezoelectric layers for the sensor and actuator,is modeled by the fourth-order shear deformation *** core(honeycomb,truss,and corrugated)is analyzed for the bearing of transverse shear *** results show that the honeycomb core has a greater effect on the *** the parameters related to the core and the weight percentage of graphene increase,the frequency *** uniform distribution of graphene platelets results in the lowest natural frequency while the natural frequency ***,without taking into account the piezoelectric layers,the third-order shear deformation theory(TSDT)and fourth-order shear deformation theory(fOSDT)align ***,when the piezoelectric layers are incorporated,these two theories diverge significantly,with the frequencies in the fOSDT being lower than those in the TSDT.

关键词： vibration and control doubly curved shell micro-composite honeycomb truss corrugate core

Impact of wastewater reuse on cobalt status in Egyptian environment

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Journal of Environmental Sciences 2003年第3期15卷 388-395页

作者： m.f. Abdel-Sabour Soil and Water Research Department Nuclear Research Center Atomic Energy Authority

Cobalt is used in the manufacture of alloys, catalysts in the petroleum industry, catalytic converters, and paint pigments. Thus the potential for Co releases into the environment is highly increased. Use of waste sludges and sewage effluent to fertilize and irrigate soils has also increased soil Co concentrations. Total cobalt contents of alluvial delta soil of Egypt show considerable variation ranging from 13.1 to 64.7 ppm. The impact of either wastewater irrigation or industrial activities on soil total Co was obvious due to accumulation of organic matter and solid waste in the surface soil samples. food crops and vegetables should not be grown on soil highly contaminated by Co. It is noteworthy that the delayed neutron activation analysis(DNAA) technique could be used successfully for total Co determination due to its high sensitivity. It is quit clearly that dust samples of Cairo City contains higher Co level, as compared to Suez Canal Region(Ismailia, Port Said and El-Suez cities). The high values in Cairo City may be due to the existence of industries around the city and the intensive traffic. To minimize Co environmental hazards, waste effluents should be treated on site. Thus, levels of potentially toxic Co needs to be continuously monitored and should be removed during several treatment processes before the disposal of these wastes.

关键词： cobalt environment Egypt

Surface morphology and impurity distribution of electron beam recrystallized silicon films on low cost substrates for solar cell absorber

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Rare metals 2006年第z1期25卷 195-200页

作者： GROmBALL f müLLER J Department of mikrosystemtechnik Technische Universitt Hamburg-Harburg Hamburg 21073 Germany

A line shaped electron beam recrystallised polycrystalline silicon film on the low cost substrate was investigated for the use of the solar cell absorber. The applied EB energy density strongly influences the surface morphology of the film system. Lower EB energy density results in droplet morphology and the rougher SiO2 capping layer due to the low fluidity. With the energy increasing, the capping layer becomes smooth and continuous and less and small pinholes form in the silicon film. Tungstendisilicide (WSi2) is formed at the interface tungsten/silicon but also at the grain boundaries of the silicon. Because of the fast melting and cooling of the silicon film, the eutectic of silicon and tungstendisilicide mainly forms at the grain boundary of the primary silicon dendrites. The SEm-EDX analysis shows that there are no chlorine and hydrogen in the area surrounding a pinhole after recrystallization because of outgassing during the solidification.

关键词： polycrystalline silicon film solar cell recrystallization energy surface morphology outgassing

Nonlinear continuous bi-inductance electrical line with dissipative elements:Dynamics of the low frequency modulated waves

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Chinese Physics B 2020年第4期29卷 179-189页

作者： S m Ngounou f B Pelap Unite de Recherche de mecanique et de modelisation des Systèmes Physiques(UR-2 mSP) Faculte des SciencesUniversite de DschangBP 69 DschangCameroun Unite de Recherche de matiere Condensee d'Electronique et de Traitement du Signal(UR-mACETS) Faculte des SciencesUniversite de DschangBP 67 DschangCameroun

The dynamics of modulated waves in a nonlinear bi-inductance transmission line with dissipative elements are *** show the existence of two frequency modes and carry out intensive investigations on the low frequency *** to the multiple scales method,the behavior of these waves is investigated and the dissipative effects are *** appears that the dissipation coefficient increases with the carrier wave *** the continuous approximation,we derive that the propagation of these waves is governed by the complex Ginzburg-Landau equation instead of the Korteweg-de-Vries equation as previously *** studies of the dynamics of plane waves in the line reveal the existence of three additional regions in the dispersion curve where the modulational phenomenon is *** the low frequency mode,we demonstrate that the network allows the propagation of dark and bright *** findings are in perfect agreement with the analytical predictions.

关键词： dissipative bi-inductance network low frequency mode continuous approximation complex Ginzburg-Landau equation

Dynamics of high-frequency modulated waves in a nonlinear dissipative continuous bi-inductance network

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Chinese Physics B 2021年第6期30卷 193-205页

作者： S m Ngounou f B Pelap Unitéde Recherche de mécanique et de modélisation des Systèmes Physiques(UR-2 mSP) Facultédes SciencesUniversitéde DschangBP 69 DschangCameroun Unitéde Recherche de matière Condensée d'Electronique et de Traitement du Signal(UR-mACETS) Facultédes SciencesUniversitéde DschangBP 67 DschangCameroun

This paper presents intensive investigation of dynamics of high frequency nonlinear modulated excitations in a damped bimodal lattice. The effects of the dissipation are considered through a linear dissipation coefficient whose evolution in terms of the carrier wave frequency is checked. There appears that the dissipation coefficient increases with the carrier wave frequency. In the linear limit and for high frequency waves, study of the asymptotic behavior of plane waves reveals the existence of two additional regions in the dispersion curve where the modulational phenomenon is observed compared to the lossless line. Based on the multiple scales method exploited in the continuum approximation using an appropriate decoupling ansatz for the voltage of the two different cells, it appears that the motion of modulated waves is described by a dissipative complex Ginzburg–Landau equation instead of a Korteweg–de Vries equation. We also show that this amplitude wave equation admits envelope and hole solitons in the high frequency mode. from basic sources, we design a programmable electronic generator of complex signals with desired characteristics, which delivers signals exploited as input waves for all our numerical simulations. These simulations are performed in the LTspice software that uses realistic components and give the results that corroborate perfectly our analytical predictions.

关键词： dissipative bi-inductance network high-frequency mode continuous approximation dissipative complex Ginzburg–Landau equation programmable electronic generator LT-Pspice observations

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

The embryology of persistent cloaca and urogenital sinus malformations

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Asian Journal of Andrology 2020年第2期22卷 124-128页

作者： David f m Thomas University of Leeds LeedsWest Yorkshire LS29JTUK

Cloacal malformations are characterized by the confluence of the lower urinary tract,the female reproductive tract,and the rectum to create a common channel with a single opening on the *** presence of a cloaca is a normal phase of early human embryological *** the 4^th and 7^th weeks of gestation,the cloaca undergoes subdivision to form the hindgut and urogenital *** of this process results in the congenital anomaly termed persistent cloaca(PC).The term urorectal septum malformation sequence(URSmS)is also used to describe this *** classic description of this process which is still cited in many standard textbooks dates from the 19th ***,this has been increasingly called into question by the findings of studies using modern scientific *** sinus anomalies are defined by the confluence of the urethra and vagina to form a common channel of varying length with a single perineal *** this condition,the anorectal canal opens separately on the *** presence of a urogenital sinus represents a transient phase of the normal development of the lower genital tract in the female ***,the form of urogenital sinus most commonly encountered in the developed world is a feature of disordered sexual differentiation and does not arise simply from the persistence of the anatomical structure which is a feature of normal fetal development.

关键词： cloaca embryology urogenital sinus