Limiting Hardening Stress Levels in Sheet Glass

The limiting level of sheet glass hardening is presented based on three classification strength criteria and is equal to about 500 MPa.     

The photopolymerisation of methacrylic acid by colloidal semiconductors

Summary Methacrylic acid was photopolymerised using CdS and composite, CdS/HgS and CdS/TiO₂, colloidal semiconductor particles as initiators. The previously proposed photoinitiation mechanism involving the photogenerated positive hole in the valence band of the CdS colloid was confirmed by the electron scavenging action of TiO₂. The effect of pH on the course of the polymerisation was investigated and is discussed.     

Fractures of Structural Steels (Part 2)

Fractures of group II (according to the classification given in Part 1) are described in detail. The deviations of the structure of a fracture from the groups of fiber and crystalline fractures are explained by the chemical micro- and macroinhomogeneity of the metal. The characteristics of fractures, the causes of their formation, the methods for fighting and eliminating them, and the interrelation with the mechanical properties of the steel are described. Every kind of fracture is illustrated.     

Volume-Surface Hardening of High-Strength Bolts from Carbon Steels for Line Rail Joints

Metal Science and Heat Treatment -     

On global exponential stability for impulsive cellular neural networks with time-varying delays

In this paper, the problem of global exponential stability for cellular neural networks (CNNs) with time-varying delays and fixed moments of impulsive effect is studied. A new sufficient condition has been presented ensuring the global exponential stability of the equilibrium points by using piecewise continuous Lyapunov functions and the Razumikhin technique combined with Young’s inequality. The results established here extend those given previously in the literature. Compared with the method of Lyapunov functionals as in most previous studies, our method is simpler and more effective for stability analysis.     

The structure of glasses in the TeO2-P2O5 system

The co-effects of two glass-formers in the TeO₂-P₂O₅ system are studied on the basis of neutron diffraction data. The curves for the radial distribution function (RDF) obtained show a high extent of destruction of the short-range order in the tellurite matrix, while the basic co-ordination PO₄ polyhedron remains unchanged. The co-ordination number (cn) of the Te atom changes from 4 to 3+1 and marked tendency towards elongation of the Te-O distances over 2.3 Å is observed. The considerably higher stability of the PO₄ polyhedra and their strong influence on the TeO₄ polyhedra is established. The observed smearing effect of the Te-Te, Te-second O and O-second O distances in the range of 3.8 to 3.9 Å in other tellurite glasses is also characteristic of this system. A structural interpretation of the liquid-liquid immiscibility on the short-range order level in the system is given. A critical composition with 26±5% of the second glass-former is established, above which concentration a stable immiscibility in the tellurite systems is observed. An attempt is made to construct two adequate structural models (microhomogeneous and microheterogeneous) for the short-range order in the glasses studied.     

Almost periodic solutions for impulsive fractional differential equations

In this paper, we consider the existence of almost periodic solutions for impulsive fractional evolution equations involving Caputo fractional derivative. The main results are obtained by means of the theory of operators semi-group, probability density functions, fixed point theorems and the techniques based on fractional calculus. An example is also discussed to illustrate the theory. Some known results are improved and generalized.     

DNA Antenna Tile‐Associated Deoxyribozyme Sensor with Improved Sensitivity

Some natural enzymes increase the rate of diffusion‐limited reactions by facilitating substrate flow to their active sites. Inspired by this natural phenomenon, we developed a strategy for efficient substrate delivery to a deoxyribozyme (DZ) catalytic sensor. This resulted in a three‐ to fourfold increase in sensitivity and up to a ninefold improvement in the detection limit. The reported strategy can be used to enhance catalytic efficiency of diffusion‐limited enzymes and to improve sensitivity of enzyme‐based biosensors.     

Uncertain impulsive differential systems of fractional order: almost periodic solutions

In this paper, we investigate the existence and stability of almost periodic solutions of impulsive fractional-order differential systems with uncertain parameters. The impulses are realised at fixed moments of time. For the first time, we determine the impact of the uncertainties on the qualitative behaviour of such systems. The main criteria for the existence of almost periodic solutions are proved by employing the fractional Lyapunov method. The global perfect robust uniform-asymptotic stability of such solutions is also considered. We apply our results to uncertain impulsive neural network systems of fractional order.