Pentakis(carbamide)dioxoneptunium(V) Nitrate [NpO2{OC(NH2)2}5](NO3): Synthesis,Crystal Structure,and Some Properties

X-ray diffraction and spectroscopic data for a new Np(V) compound, namely, [NpO₂{OC(NH₂)₂}₅](NO₃) (I) are presented. Crystals are monoclinic, space group P2₁, a = 11.142(2) Å, b = 7.6379(9) Å, c = 11.143(2) Å, = 108.9(1)°, Z = 2, V = 897.1(2) ų. The neptunium atom has a typical pentagonal-bipyramidal environment with five oxygen atoms of the carbamide molecules in the equatorial plane. The nitrate ion is in the outer sphere. Carbamide is a strong molecular ligand with respect to Np(V) and hence, cation–cation bonds of the NpO₂ ⁺ ions are not realized in structure I. The wave length of the f–f transition in the electronic absorption spectra of crystalline complex I and Np(V) in a saturated carbamide solution is virtually the same and is equal to 991 nm.     

Crash-Conformational Kinematics of the Covalent Lattice of Diamond on Melting

Using the model potential approach we have obtained a generalized potential of interatomic interactions for two condensed states providing an abrupt change in thermodynamic functions at a point of a solid to liquid transition. A kinematic model is considered for the transition of the diamond lattice with pure covalent bonds to the melted state. The model is based on the concept of crash destruction of the lattice during the conformational transformation of the initial symmetry of the chosen atomic group. The kinetic energy of the thermal motions of atoms does not exceed the potential energy of lattice atomization. The kinematic patterns of the positions of 150 atoms at T T _m and T T _m are given for the two-dimensional hexagonal net.     

Measurement of the energy penetration depth into solid targets irradiated by ultrashort laser pulses

The energy penetration depth of a short (100 fs) Ti-sapphire laser pulse (0.8 &mgr;m) of intensity 3x10(16) W/cm(2), in solid density materials has been measured. High-Z (BaF2) and low-Z (MgF2) solid layers targets were used. The penetration depth was determined from the measurement of the x-ray emission spectra, as a function of the target thickness. The investigation of these spectra showed that in the low-Z case, solid density material to a depth of 50 nm was heated to a peak electron temperature of approximately 150 eV. For the high-Z material, the penetration depth corresponding to this temperature exceeded 100 nm. This is evidence of a larger heat penetration depth in a high-Z material in comparison to a low-Z material. A model based on electron heat conduction is used to estimate the energy penetration depth. It is suggested that the larger heat penetration in high-Z material is due to heating of the material, caused by the radiation flux, generated by the electron heat conduction.     

Two-dimensional image magnification in an asymmetric-reflection X-ray microscope

The experimental results on the two-dimensional 20× magnification of an x-ray image obtained in an asymmetric-reflection x-ray microscope with the use of a laboratory source of x rays are discussed. The field of view is determined by the linear sizes of the detector and is equal to 0.5 × 0.5 mm in our experiment for an exposure time of 600 s.     

Simulation of pulsed-laser-induced explosive boiling

Bulk evaporation process in absorbing condensed matter irradiated with laser pulses was studied using the one-dimensional thermal model with additional interfaces between different phases. Within this approach, it was shown that the repeated explosive boiling mode can be achieved using nanosecond laser pulses, if the nucleation time is shorter than 0.1 ns. This mode can be observed if the surface pressure is lower than the critical pressure P _c of the liquid-vapor phase transition. The dependences of these processes on the laser pulse intensity and duration, as well as on evaporation kinetics were studied. Explosive boiling and spallation of a transparent liquid film on a pulse-heated absorbing target, as well as the photoacoustic signal in the target before the explosion, were considered.     

Scale transformations in phase space and stretched states of a harmonic oscillator

We consider scale transformations (q, p) → (λq, λp) in phase space. They induce transformations of the Husimi functions H(q, p) defined in this space. We consider the Husimi functions for states that are arbitrary superpositions of n-particle states of a harmonic oscillator. We develop a method that allows finding so-called stretched states to which these superpositions transform under such a scale transformation. We study the properties of the stretched states and calculate their density matrices in explicit form. We establish that the density matrix structure can be described using negative binomial distributions. We find expressions for the energy and entropy of stretched states and calculate the means of the number-ofstates operator. We give the form of the Heisenberg and Robertson–Schrödinger uncertainty relations for stretched states.     

Electrosynthesis and biological properties of persulfate–chloride solutions

A method for electrochemical synthesis of medical solutions for oxidation of toxic substances in the human organism has been developed. The method is based on electrooxidation of sodium sulfate in the presence of chloride and NaOH microadditions (in amounts that provide рН 13) in a filter-press membrane electrolyzer. A diagram is presented for choosing the optimum ratio between the current density and the flow rate of electrolyte during the electrosynthesis of a medical solution. The use of an electrolyte of the suggested composition under the optimum electrosynthesis conditions leads to solutions with physiological рН values (7.2–7.4) and high oxidative ability with respect to Micrococcus sp. and Staphylococcus coag (–), but there was no injuring effect on blood cells.     

Multilevel preconditioning and low‐rank tensor iteration for space–time simultaneous discretizations of parabolic PDEs

This paper addresses the solution of parabolic evolution equations simultaneously in space and time as may be of interest in, for example, optimal control problems constrained by such equations. As a model problem, we consider the heat equation posed on the unit cube in Euclidean space of moderately high dimension. An a priori stable minimal residual Petrov–Galerkin variational formulation of the heat equation in space–time results in a generalized least squares problem. This formulation admits a unique, quasi‐optimal solution in the natural space–time Hilbert space and serves as a basis for the development of space–time compressive solution algorithms. The solution of the heat equation is obtained by applying the conjugate gradient method to the normal equations of the generalized least squares problem. Starting from stable subspace splittings in space and in time, multilevel space–time preconditioners for the normal equations are derived. In order to reduce the complexity of the full space–time problem, all computations are performed in a compressed or sparse format called the hierarchical Tucker format, supposing that the input data are available in this format. In order to maintain sparsity, compression of the iterates within the hierarchical Tucker format is performed in each conjugate gradient iteration. Its application to vectors in the hierarchical Tucker format is detailed. Finally, numerical results in up to five spatial dimensions based on the recently developed htucker toolbox for MATLAB are presented. Copyright © 2014 John Wiley & Sons, Ltd.     

Study of explosive boiling of transparent liquid on metal substrate exposed to nanosecond laser pulses

Preliminary experimental investigation of photoacoustic pressure signals induced by nanosecond laser pulses in aluminum targets contacting a water layer was performed. It was shown that for some laser intensities the signal has a two-peak structure. The first peak is due to the thermoelastic effect, while the other results from the explosive evaporation. At low intensities, only the first peak is observed. At sufficiently high intensities, the signal recovers the one-peak shape and becomes narrower as compared with the two-peak shape because of the rapid increase in evaporation pressure and earlier beginning of the explosive evaporation.