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91.
Nucleus-acoustic(NA) solitary waves(SWs) propagating in a self-gravitating degenerate quantum plasma(SDQP)system(containing non-relativistically degenerate heavy and light nuclei,and non-/ultra-relativistically degenerate electrons) have been theoretically investigated.The modified Korteweg–de Vries(m K-d V) equation has been derived for both planar and non-planar geometry by employing the reductive perturbation technique.It is shown that the NA SWs exist with positive(negative) electrostatic(self-gravitational) potential.It is also observed that the effects of non-/ultra-relativistically degenerate electron pressure,dynamics of non-relativistically light nuclei,spherical geometry,etc.significantly modify the basic features(e.g.,amplitude,width,speed,etc.) of the NA SWs.The applications of our results,which are relevant to astrophysical compact objects,like white dwarfs and neutron stars,are briefly discussed. 相似文献
92.
Deiaa Elaarabi Abdelmorhit Laissaoui Amina Guessous Benkdad Azzouz Hajoub Chakir 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(3):1069-1076
Journal of Radioanalytical and Nuclear Chemistry - 210Po, 210Pb, and 137Cs activities were measured using gamma and alpha spectrometry in commonly consumed seafood collected from the local fish... 相似文献
93.
Vortex dynamics and mass entrainment in turbulent lobed jets with and without lobe deflection angles 总被引:2,自引:0,他引:2
Passive control of jet flows in order to enhance mixing and entrainment is of wide applicative interest. Our purpose is to
develop new air diffusers for HVAC systems, by using lobed geometry nozzles, in order to ameliorate users the thermal comfort.
Two turbulent 6-lobed air jets with and without lobe deflection angles were studied experimentally and compared with a reference
circular jet having the same initial Reynolds number. The main objective was to analyze the modifications occurring in the
vortex dynamics of the flow, firstly by replacing a circular tube with a straight lobed tube, and secondly by a lobed tube
having a double inclination of the lobes. Rapid visualizations of the flows and hot-wire measurements of the streamwise velocity
spectra allow understanding the vortex roll-up mechanisms. Unlike the circular jet, where the primary rings are continuous,
the Kelvin–Helmholtz vortices in the lobed jet flows were found to be discontinuous. The resulting “ring segments” detach
at different frequencies whether they are shed in the lobe troughs or at the lobe sides. One explanation relies on the strong
variation of the exit plane curvature. Additionally, a speculative scenario of the vortical dynamics is advanced by the authors.
The discontinuous nature of the K–H vortices enables the development of secondary streamwise structures, non-influenced by
the passage of the primary structures as in the case of the circular jet. Thus, the momentum flux transport role played by
the streamwise structures is rendered more efficient and leads to a spectacular increase in the entrainment rate in the initial
region. The amount of fluid being entrained in the lobed jet by the streamwise structures is drastically amplified by the
double inclination of the nozzle exit boundary. 相似文献
94.
Amina Benallou Baghdad Hadri Juan Martinez-Vega Nour El Islam Boukortt 《The European Physical Journal B - Condensed Matter and Complex Systems》2018,91(4):61
The effect of percolation threshold on the behaviour of electrical conductivity at high electric field of insulating polymers has been briefly investigated in literature. Sometimes the dead ends links are not taken into account in the study of the electric field effect on the electrical properties. In this work, we present a theoretical framework and Monte Carlo simulation of the behaviour of the electric conductivity at high electric field based on the percolation theory using the traps energies levels which are distributed according to distribution law (uniform, Gaussian, and power-law). When a solid insulating material is subjected to a high electric field, and during trapping mechanism the dead ends of traps affect with decreasing the electric conductivity according to the traps energies levels, the correlation length of the clusters, the length of the dead ends, and the concentration of the accessible positions for the electrons. A reasonably good agreement is obtained between simulation results and the theoretical framework. 相似文献
95.
Amassad Amina; Fabre Caroline; Sofonea Mircea 《IMA Journal of Applied Mathematics》2004,69(5):463-482
We consider a quasistatic contact problem between a viscoplasticbody and an obstacle, the so-called foundation. The contactis modelled with normal compliance and the associated versionof Coulomb's law of dry friction. We derive a variational formulationof the problem and, under a smallness assumption on the normalcompliance functions, we establish the existence of a weak solutionto the model. The proof is carried out in several steps. Itis based on a time-discretization method, arguments of monotonicityand compactness, Banach fixed point theorem and Schauder fixedpoint theorem. 相似文献
96.
Qurat-ul-ain Khalid Amina Khan Haq Nawaz Bhatti Sana Sadaf Abida Kausar Siham A. Alissa Mona K. Alghaith Munawar Iqbal 《Arabian Journal of Chemistry》2021,14(7):103227
This work was designed to synthesize and characterize biocomposites for the adsorptive elimination of insecticide (nitenpyram). Different biocomposites were synthesized of polyaniline (PAN-PH), polypyrrole (PPY-PH) and sodium alginate (Na-Al-PH) with cellulosic biomass of peanut husk (PH), which was characterized fourier-transform infrared spectroscopy (FTIR), pHpzc and scanning electron microscope (SEM). In batch mode, different variables, i.e., contact time, pH, temperature, NP (nitenpyram) concentration and adsorbent dose effects were investigated. The adsorption capacities of PH, PAN-PH, PPY-PH and Na-Al-PH were recorded to be 13.0, 14.43, 13.61 and 11.91 (mg/g), respectively at 30 °C, 60 min contact time, 0.05 g and 2.0 pH. Pseudo second order kinetic and Freundlich isotherm models best explained the NP adsorption data. An exothermic adsorption nature of NP adsorption was observed on to PH, PAN-PH, PPY-PH and Na-Al-PH. The NP desorption was efficient with NaOH and biocomposites are competent for the adsorptive removal of NP, which can utilized for NP remediation in effluents. 相似文献
97.
A simple and sensitive fluorometric method for determination of ketorolac tromethamine was studied. The method depends on oxidation of the drug with cerium(IV) and subsequent monitoring of the fluorescence of the induced cerium(III) at lambda(em) 365 nm after excitation at 255 nm. Different variables affecting the reaction conditions, such as the concentrations of cerium(IV), sulfuric acid concentration, reaction time, and temperature, were carefully studied and optimized. Under the optimum conditions, a linear relationship was found between the relative fluorescence intensity and the concentration of the investigated drug in the range of 0.1-0.8 microg/mL. No interferences could be observed from the excipients commonly present in dosage forms. The proposed method was successfully applied to the analysis of the investigated drug in its pure form, pharmaceutical preparations, and biological fluids with good accuracy and precision. The recoveries for pharmaceutical formulations ranged from 99.8-101.0 +/- 0.6% for tablets, 98.5-101.0 +/- 1.0% for ampoules, and 99.0-100.5 +/- 0.7% for eye drops. The results obtained by the proposed method were satisfactory compared with those obtained by the official method. The recoveries for biological fluids were 99.1-100.4 +/- 0.7 and 99.0-100.0 +/- 0.5% for plasma and urine, respectively. 相似文献
98.
Journal of Russian Laser Research - Optical bistability (OB) is theoretically examined for a double quantum dot (QD) system placed in a ring cavity that is injected with a squeezed vacuum (SV)... 相似文献
99.
Particle image velocimetry measurements and time-resolved visualization are used for the reconstruction of the Kelvin–Helmholtz
vortex passing in the near field of a round jet and of a lobed jet. For the round jet, the entrainment is produced in the
braid region, where streamwise structures develop. In the Kelvin–Helmholtz ring, entrainment is dramatically affected by the
attenuation of the streamwise structures. As for the lobed jet, the special geometry introduces a transverse shear leading
to a breakdown of the Kelvin–Helmholtz structures into “ring segments.” Streamwise structures continuously develop at the
resulting discontinuity regions and control the lobed jet self-induction. In this case, the entrainment rate is less affected
by the primary structures dynamics. 相似文献
100.
Shelley N. Jackson Amina S. Woods 《Journal of the American Society for Mass Spectrometry》2013,24(12):1950-1956
Noncovalent interactions govern how molecules communicate. Mass spectrometry is an important and versatile tool for the analysis of noncovalent complexes (NCX). Electrospray mass spectrometry (ESI-MS) is the most widely used MS technique for the study of NCXs because of its softer ionization and easy compatibility with the solution phase of NCX mixtures. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has also been used to study NCXs. However, successful analysis depends upon several experimental factors, such as matrix selection, solution pH, and instrumental parameters. In this study, we employ MALDI imaging mass spectrometry to investigate the location and formation of NCXs, involving both peptides and proteins, in a MALDI sample spot. Figure
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