Coprecipitation of Naphthol Azosulfonates with Organic Coprecipitants and Its Use in Flow-Injection Analysis

The coprecipitation of azo compounds based on 4-nitrophenyl- and 4-sulfophenyldiazonium naphthol sulfonates as their diphenylguanidinium ion-pair complexes with analogous compounds of naphthalene-2-sulfonic acid and 4-phenylsulfodiazonium is investigated. The optimization of the coprecipitation is considered based on the notions of the driving force of the cocrystallization of impurities. The optical characteristics of colored ion-pair complexes are measured. It is found that the water solubility is decreased most substantially for azosulfonates with hydrophobic nitro groups and with no more than two sulfo groups in different aromatic nuclei, which can lead to a decrease in the detection limit due to preconcentration by coprecipitation, which stimulates the thermodynamic flux of concentrate elution. Coprecipitation is combined with flow-injection analysis in the on-line mode, and new procedures are developed for determining naphthol sulfonates and related azo compounds with the detection limit equal to 0.003–0.006 mg/50 mL.     

Electrochemical Emission during Discontinuous Creep of Aluminum‒Magnesium Alloy

Crystallography Reports - It is experimentally established that the discontinuous creep of aluminum?magnesium alloy AlMg6, deformed in an aqueous medium, is accompanied by discrete...     

Acoustic Response of Multilayer Biostructures to Laser Irradiation and the Possibility of Using It in Surgery and Diagnostics

Aspects of the destructive action of short laser pulses on multilayer biological structures are considered theoretically. The proposed mechanisms of destruction of the native structure are cavitation, explosive evaporation, and thermocoagulation. The parameters (power and duration) of laser radiation pulses ( = 534 nm, controlling which one can choose the character of the destructive (from mechanical to pure thermal) action on the skin, have been calculated. The possibility of early diagnostics of pigmented tumors by the parameters of the hydroacoustic response of the medium is shown.     

A physical model of laser-assisted blocking of blood flow: II. Pulse modulation of radiation

A method for the calculation of blocking of blood flow upon treatment of vessel pathologies by laser irradiation at a wavelength of 530 nm are considered. The model is based on the assumption that blood-vessel occlusion is a consequence of preceding photothermal coagulation of internal layers of the vessel wall. The irradiation regimes are determined that provide homogeneous and highly efficient coagulation of the vessel wall under irradiation of tissues by series of short radiation pulses.     

On the deformation of an elastic half-space with a thin slit for mixed conditions on its boundary

The problem of the state of stress and strain in an elastic half-space with a cutout in the shape of a circular slot is solved by Kelvin's method /1/. The conditions on the slot are satisfied in a suitable manner by selecting the scalar and vector mass force potentials as generalized functions concentrated at the slot. The problem reduces to a system of Fredholm integral equations of the second kind in a semi-infinite interval. The solution for an elastic space with a slot is obtained in final form in the limiting case, which enables an estimate to be made of the magnitude of the settling of the earth's surface as a result of oil or gas deposit development.     

Numerical modeling of the action of pulse laser radiation on small absorbing targets

The features of acoustic wave generation in a dense medium due to the absorption of laser pulse radiation were analyzed numerically, based on solutions to the equations of motion in Lagrange form. The influence of thermal and acoustic mechanisms in changes of physical parameters in a dense medium was studied over a wide range of temporal and energetic characteristics typical of laser systems.     

Effect of surface kinetics on the dendritic growth of ice in supercooled water

The dendritic growth of ice in supercooled water was investigated experimentally. It has been found that, with an increase in the degree of initial supercooling of water, the data of measuring the growth rate of the dendrite tip v _t, the average distance between the tip and the first side branch z? _SB, and the fractal dimension d _f of the dendrite contour diverge from the analytically and numerically calculated parameters of dendritic growth. It is shown that the discrepancy between experiment and theory is due to the transition from the diffusional growth to the growth controlled by the surface kinetics. The nature of the anisotropic surface kinetics of ice growth in supercooled water is discussed.     

Effect of Laser Processing on Strength and Portevin–Le Chatelier Serrated Deformation of Aluminum Alloy

Physics of the Solid State - The effect of surface processing by laser IR radiation on strength and Portevin–Le Chatelier serrated deformation of AlMg6 aluminum–magnesium alloy is...