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131.
B. Dromey D. Adams S. Kar C. Bellei D. C. Carroll R. J. Clarke J. S. Green S. Kneip K. Markey S. R. Nagel P. T. Simpson L. Willingale P. McKenna D. Neely Z. Najmudin K. Krushelnick P. A. Norreys M. Zepf 《The European physical journal. Special topics》2009,175(1):57-60
X-ray harmonic radiation extending to 3.3 Å, 3.8 keV from Petawatt class laser-solid interactions is presented. The harmonic spectra display a relativistic limit scaling up to ~3000th order, above which an intensity dependent scaling roll-over is observed. Highly directional beamed emission for harmonic photon energy hν > 1 keV is found to be into a cone angle < 4°, significantly less than that of the incident laser cone (20°). 相似文献
132.
M. Borghesi T. Toncian J. Fuchs C. A. Cecchetti L. Romagnani S. Kar K. Quinn B. Ramakrishna P. A. Wilson P. Antici P. Audebert E. Brambrink A. Pipahl R. Jung M. Amin O. Willi R. J. Clarke M. Notley P. Mora T. Grismayer E. D’Humières Y. Sentoku 《The European physical journal. Special topics》2009,175(1):105-110
The acceleration of high-energy ion beams following the interaction of short (t < 1 ps) and intense (Iλ2 > 1018 W cm-2 μm2) laser pulses with solid targets is a field of research currently attracting high interest in the scientific community, due
to some of the unique properties of these ion sources, promising routes toward the optimization of their energy content, and
a number of possible, innovative applications in the scientific, technological and medical areas. Work on the characterization
and development of these sources has progressed enormously over the past few years, thanks to the contribution of many groups
worldwide. This paper will report some recent results, obtained in experiments carried out at the RAL and LULI laboratories,
in which we investigated the ion acceleration mechanism, developed a technique to control the ion beam divergence and energy
spectrum, and applied a proton radiography technique to investigate electric and magnetic field production following laser-matter
interaction. 相似文献
133.
L. E. Kar’kina I. N. Kar’kin Yu. N. Gornostyrev L. I. Yakovenkova 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(8):1030-1033
The microscopic mechanisms controlling the atomic rearrangements during agglomeration of Ni particles 3 to 7 nm in size at
temperatures T = 0.6–0.95 T
m
have been studied by the molecular dynamics method. Pentagonally twinned crystals were obtained as a result of coalescence
for the disorientations corresponding to special Σ11 and Σ27 large-angle boundaries. 相似文献
134.
Vamsi Krishna Balla Susmita Bose Amit Bandyopadhyay 《Optics and Lasers in Engineering》2009,47(6):651-655
The feasibility of enhancing thermal conductivity of Al–4Cu–1Mg alloy by depositing 80Cu–20Mo coating using high-power lasers has been examined. Coatings of 667±2.5 μm thickness were formed with metallurgically sound interface. Results showed an 86% increase in the thermal conductivity of Al–4Cu–1Mg alloy due to laser-deposited 80Cu–20Mo alloy coating. This coating approach can potentially be used on low coefficient of thermal expansion metal matrix composites to enhance their thermal conductivity in electronic devices. 相似文献
135.
The purpose of this investigation was to study the effect of Streptomyces erumpens cells immobilized in various matrices, i.e., agar–agar, polyacrylamide, and luffa (Luffa cylindrica L.) sponge for production of α-amylase. Luffa sponge was found to be 21% and 51% more effective in enzyme yield than agar–agar
and polyacrylamide, respectively. Response surface methodology was used to evaluate the effect of three main variables, i.e.,
incubation period, pH, and temperature on enzyme production with immobilized luffa cells. The experimental results showed
that the optimum incubation period, pH, and temperature were 36h, 6.0, and 50 °C, respectively. The repeated batch fermentation
of immobilized cells in shake flasks showed that S. erumpens cells were more or less equally physiologically active on the support even after three cycles of fermentation (3,830–3,575
units). The application of S. erumpens crude enzyme in liquefying cassava starch was studied. The maximum hydrolysis of cassava starch (85%) was obtained with the
application of 4ml (15,200 units) of crude enzyme after 5 h of incubation. 相似文献
136.
137.
As a generalization of an orthodox semigroup in the class of regular semigroups, a type W semigroup was first investigated
by El-Qallali and Fountain. As an analogy of the type W semigroups in the class of abundant semigroups, we introduce the U-orthodox semigroups. It is shown that the maximum congruence μ contained in
on U-orthodox semigroups can be determined. As a consequence, we show that a U-orthodox semigroup S can be expressed by the spined product of a Hall semigroup W
U
and a V-ample semigroup (T,V). This theorem not only generalizes a known result of Hall-Yamada for orthodox semigroups but also generalizes another known
result of El-Qallali and Fountain for type W semigroups.
This work was supported by National Natural Science Foundation of China (Grant No. 10671151) and Natural Science Foundation
of Shaanxi Province (Grant No. SJ08A06), and partially by UGC (HK) (Grant No. 2160123) 相似文献
138.
In this paper, we make a systematic analysis of the dynamics of a predator–prey system with type-II functional response, in which the predator growth rate is affected by the presence of a super predator. The main aim of this research is to study the consequences of the presence of a super predator on the system dynamics. The existence and stability of the different possible equilibrium points are studied, and we conclude that the maximum consumption rate of a super predator plays a key role in determining the eventual state of the ecosystem. A detailed bifurcation analysis is carried out through numerical simulations, and we observe that theoretically it is possible to control the dynamics of the system by manipulating the consumption rate of the super predator. 相似文献
139.
Amrita Ghosh Satyaki Kar Sudhakar Yarlagadda 《The European Physical Journal B - Condensed Matter and Complex Systems》2018,91(9):205
We derive an effective Hamiltonian for the two-dimensional Hubbard–Holstein model in the regimes of strong electron–electron and strong electron–phonon interactions by using a nonperturbative approach. In the parameter region where the system manifests the existence of a correlated singlet phase, the effective Hamiltonian transforms to a t1 ? V 1 ? V 2 ? V 3 Hamiltonian for hard-core-bosons on a checkerboard lattice. We employ quantum Monte Carlo simulations, involving stochastic-series-expansion technique, to obtain the ground state phase diagram. At filling 1∕8, as the strength of off-site repulsion increases, the system undergoes a first-order transition from a superfluid to a diagonal striped solid with ordering wavevector \(\vec{Q}\) = (π∕4, 3π∕4) or (π∕4, 5π∕4). Unlike the one-dimensional situation, our results in the two-dimensional case reveal a supersolid phase (corresponding to the diagonal striped solid) around filling 1∕8 and at large off-site repulsions. Furthermore, for small off-site repulsions, we witness a valence bond solid at one-fourth filling and tiny phase-separated regions at slightly higher fillings. 相似文献
140.
Sabyasachi Kar Yu-Shu Wang Zishi Jiang Yang Wang Yew Kam Ho 《Chinese Journal of Physics (Taipei)》2018,56(6):3085-3098
In this article, we review or report recent works on atomic wavelengths in screening environments. We mainly review recent works on the transition, tune-out and magic wavelengths with Coulomb and screened Coulomb potentials. We also present our investigation on tune-out and magic wavelengths for two-electron Yukawa atoms. The various transition wavelengths for two-electron systems with and without screening environments are also presented. 相似文献