Role of Bulk Vaporization in the Dynamics of Laser-Induced Erosion Plumes of Metals

In different regimes of exposure of metals to pulsed laser radiation, we show the role played by the liquid-drop phase formed from the target material in a laser-induced erosion plume due to bulk vaporization, in the dynamics of this plume. For some metals, the ranges of power densities of the acting laser radiation, at which the condensed-phase particles influence the passage of laser radiation to the target surface, have been determined experimentally. The mechanism of realization of a low-threshold breakdown has been revealed.     

Modification of Paving Asphalts with Sulfur

Sulfur dissolved in oil components of asphalt is a binder, filler, and chemical co-reagent at once. The structure of sulfur-extended asphalt depends on its formula and heating temperature. Road pavement based on sulfur-extended asphalt demonstrates higher durability as compared to that with the conventional binders.     

Loading aircraft for military operations

In this paper, we describe an aircraft loading problem submitted by the French military agency (DGA) as part of a more general military airlift planning problem. It can be viewed as a kind of bi-dimensional bin-packing problem, with heterogeneous bins and several additional constraints. We introduce two-phase methods for solving this NP-hard problem. The first phase consists in building good initial solutions, thanks to two fast algorithms: a list-based heuristic and a loading pattern generation method. Both algorithms call a constraint-based subroutine, able to determine quickly if the items already loaded can be reshuffled to accommodate a new object. The second phase improves these preliminary solutions using local search techniques. Results obtained on real data sets are presented.     

New insights on amorphous silicon-nitride microcavities

All amorphous silicon-nitride planar optical microcavities operating in the visible range have been grown by plasma enhanced chemical vapor deposition. The luminescence intensity of the N-rich silicon-nitride layer from a microcavity with 6 period distributed Bragg reflectors (DBRs) is two order of magnitude higher than that of the luminescent layer without the cavity. Moreover, a strong directionality of the microcavities emission can be observed. Such results can be ascribed to the anisotropic optical density of states induced in the Fabry–Perot structure. The quality factors of the resonators are strictly correlated to the number of periods of the DBRs.     

Quantum-Chemical Study of Structural and Energy Characteristics of Benzonitrile Dimers

Ab initio MP2 calculations with several basis sets proved the existence of a stable benzonitrile dimer with a planar structure and a short contact between the H atom of one molecule and the N atom of another. The structure is greatly stabilized by attraction between the neighboring oppositely directed dipoles and donor-acceptor interaction between the orbital of the lone electron pair of the N′ atom and the vacant antibonding orbital localized on the C-H bond.Original Russian Text Copyright © 2004 by O. V. Sizova, E. P. Sokolova, V. I. Baranovskii, D. A. Rozmanov, and O. A. Tomashenko__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 807–815, September–October, 2004.     

Small and high-density GeSiC dots stacked on buried Ge hut-clusters in Si

Self-assembled GeSiC dots stacked on a Ge hut-cluster layer buried in Si have been investigated. The critical thickness for formation of GeSiC dots is reduced owing to the strain fields from the buried hut-clusters. By utilizing the stacked structure, the dot size is decreased and the uniformity is improved. The highest density of the GeSiC dots with stacked structures is 7.4×10¹⁰ cm⁻², which is six times larger than that of single GeSiC dots. The formation of the self-assembled GeSiC dots is strongly influenced by being stacked with buried Ge dots as well as C incorporation.     

Relationships between Electrodynamic and Quantum-Mechanical Parameters in the Theory of Quantum Transitions

Relationships between the electrodynamic (wave propagation constants) and quantum-mechanical parameters (probability of induced transitions) of interaction between energy quanta and particles of the medium are derived for dipole and paramagnetic interaction types. It is demonstrated that quantum-mechanical parameters are generally complex.     

Real-time monitoring of the desorption process of chlorine-covered Si(111)-‘1×1’ surface with second-harmonic generation

To elucidate the fundamental process underlying the semiconductor surface fabrication, isothermal desorption from a Cl/Si(111)-‘1×1’ surface was monitored by means of second-harmonic generation with 1064 nm light. During the desorption, surface Cl-coverages were obtained in real time. The temperature dependence of the desorption rates revealed that the energy barrier against chloride desorption is 2.1 eV. A very slow second phase in the recovery of the second-harmonic intensity is associated with reconstruction of 7×7 DAS structure following the desorption. The activation energy for the reconstruction was 2.4 eV.     

Induced Representations of Abelian Groups of Finite Rank

We prove that any irreducible faithful representation of an almost torsion-free Abelian group G of finite rank over a finitely generated field of characteristic zero is induced from an irreducible representation of a finitely generated subgroup of the group G.     

Effect of Conditions of Electric-Spark Dispersion of Zinc on the Quality of the Product Obtained

Influence exerted by additives introduced into the working solution, by iron or copper formedin electric-spark dispersion of these metals and zinc, on the quality of the products obtained in electric erosionwas studied.