Diffusional-kinetic model of the joint dissolution of interacting poorly soluble substances

A model of the dissolution and interaction of two poorly soluble substances with the formation of a readily soluble product was developed. The kinetic characteristics of the process were described for the dissolution of two solid substances in a planar slit between them filled with a solvent and for the dissolution of intensely stirred suspension of particles of two substances.     

Kinetics of solid state reactions with a positive feedback between the reaction and fracture

A model describing the steady-state kinetics of thermal decomposition in the solid phase occurring with a decrease in the solid phase volume and accompanied by fracture in the reaction zone is suggested. The model is based on the concept of positive feedback between the reaction and fracture. The rate of the fracture front and the size of the product fragments formed were calculated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 626–631, April, 1998.     

Ferromagnetic and spin-wave resonance in trilayer exchange-coupled structures NiFe/Cu/NiFe

SWR spectra of exchange-coupled NiFe/Cu/NiFe structures were investigated. We found that the optical satellites of exchange spin-wave modes are characterized not by the standard Kittel dependence but by their own dependence of the resonance field on the mode number: H _r ^opt(n) ∼ n ^5/2.     

Study of the Crack Resistance of Microarc Oxidation Coatings after Laser Doping with Zirconium Oxide

Technical Physics - In this paper we present the results of a study of crack resistance of a microarc oxidation coating (MAO) after laser doping with zirconium oxide. Crack resistance was...     

Astrophysical S-factors from asymptotic normalization coefficients

S-factors for direct capture reactions can be found at astrophysical energies from asymptotic normalization coefficients which provide the normalization of the tail of the overlap function. For example the overlap for ⁸B → ⁷Be+p defines the S-factor for ⁷Be (p, γ)⁸B. Peripheral transfer reactions offer a technique to determine these asymptotic normalization coefficients. As a test of the technique, the ¹⁶O(³He, d)¹⁷F reaction has been used to determine asymptotic normalization coefficients for transitions to the ground and first excited states of ¹⁷F. The S-factors for ¹⁶O(p, γ)¹⁷F calculated from these ¹⁷F → ¹⁶O+p asymptotic normalization coefficients are found to be in very good agreement with recent measurements. Following the same technique, the ¹⁰B(⁷Be, ⁸B)⁹Be and ¹⁴N(⁷Be, ⁸B)¹³C reactions have been used to measure the asymptotic normalization coefficient for ⁷Be(p, γ)⁸B. This result provides an indirect determination of S ₁₇(0).     

Gas-phase deprotonation of arylalkylamines. A collision-induced dissociation study

The collision-induced dissociation (CID) of deprotonated arylalkylamines of general formula R(1)C(6)H(4)CHR(2)CH(2)NR(3)(2) (where R(1) = H, OH, F or NO(2); R(2) = H or OH; R(3) = H or CH(3)) generated by negative chemical ionization with H(2)O and D(2)O as ionizing reagents, is discussed. The negative chemical ionization mass spectra show that, in the absence of a hydroxy group in the aromatic ring, deprotonation takes place at the benzylic position whereas the proton is lost from the OH group when present. The nitro compound forms only M(-.) ions. The CID spectra of the deprotonated molecules show that fragmentations are strongly dependent on the structural features of the molecules, namely the presence or absence of substituents in the aromatic ring or aliphatic chain. Copyright 1999 John Wiley & Sons, Ltd.     

Isolation of NO(3)(-)-N as 1-phenylazo-2-naphthol (Sudan-1) for measurement of delta(15)N

The conversion of nitrate (NO(3)(-)) to 1-phenylazo-2-naphthol (Sudan-1) has been examined as a method for natural abundance measurement of delta(15)N of NO(3)(-). The reaction results in dilution of NO(3)(-)-N with only one reagent-derived N and the product is readily concentrated from dilute samples by reverse phase chromatography. There is systematic isotopic fractionation during the reaction, but this can be allowed for by analysing known NO(3)(-) standards along with each sample set. Sudan-1 prepared from surface water samples containing approximately 50 &mgr;g NO(3)(-)-N can be analysed by automated continuous flow isotope ratio mass spectrometry with a precision of 0.2 per thousand (one standard deviation) and the accuracy is not affected by interference from other nitrogenous species in the sample or reagents. Copyright 1999 John Wiley & Sons, Ltd.     

Atomic force microscopy probing of cell elasticity

Atomic force microscopy (AFM) has recently provided the great progress in the study of micro- and nanostructures including living cells and cell organelles. Modern AFM techniques allow solving a number of problems of cell biomechanics due to simultaneous evaluation of the local mechanical properties and the topography of the living cells at a high spatial resolution and force sensitivity. Particularly, force spectroscopy is used for mapping mechanical properties of a single cell that provides information on cellular structures including cytoskeleton structure.

This entry is aimed to review the recent AFM applications for the study of dynamics and mechanical properties of intact cells associated with different cell events such as locomotion, differentiation and aging, physiological activation and electromotility, as well as cell pathology. Local mechanical characteristics of different cell types including muscle cells, endothelial and epithelial cells, neurons and glial cells, fibroblasts and osteoblasts, blood cells and sensory cells are analyzed in this paper.     

Atomic force microscopy observation of peroxynitrite-induced erythrocyte cytoskeleton reorganization

Atomic force microscopy (AFM) was used to study surface layers of fixed intact erythrocytes. Advantages of simultaneous analysis of surface topography and lateral force maps in the investigation of cytoskeleton structure were shown. Fractal analysis was applied to the lateral force maps of erythrocyte surfaces to evaluate the complexity of the cytoskeleton. Peroxynitrite was used as an oxidant to induce changes in the cytoskeleton structure of intact erythrocytes. Peroxynitrite action on whole blood leads to local abnormalities in the erythrocyte cytoskeleton structure, as well as cytoskeleton reorganization in protruded regions of crenated erythrocytes.