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Abstract  

Radiation induced grafting of acrylonitrile (ACN) on ethylene-propene diene terpolymer (EPDM) rubber film was investigated by mutual radiation grafting technique. Effect of experimental variables viz. radiation dose, dose rate, type of solvent and monomer content on extent of grafting was studied. From the kinetic studies a mathematical relation R gα[M]0.7 D 0.68 showing non-linear relationship for rate of grafting with monomer concentration and dose was deduced. The grafted samples showed increased hardness and oil resistance.

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Abstract  

Carbon is determined in gold layers electroplated on brass, by deuteron activatin analysis using the12C/d, n/13N reaction. The results range from 2 to 1300 g.g–1 and the relative standard deviation from 0.9 to 13%. It is quantitatively shown that the hardness of the gold increases with the carbon concentration and that the carbon concentration decreases with increasing plating temperature and increases to a certain limit with the plating current density.

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Abstract  

Faraday induced the mechanochemical reduction of AgCl with Zn, Sn, Fe and Cu in 1820, using trituration in a mortar. This experiment is revisited, employing a mortar-and-pestle and a ball mill as mechanochemical reactors. The reaction kinetics depends both on the thermochemical properties and the hardness of the reactants. When using Zn as the reducing agent, Faraday likely observed a mechanically induced self-sustaining process (MSR), or at least he came very close to doing so.

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Texture development during ripening of cow milk Kashkaval cheese at different temperatures (9±1 °С, 11±1 °С and 13±1 °С) was studied. Texture parameters representing cheese hardness, cohesiveness, springiness, adhesiveness, gumminess and chewiness were determined by texture profile analysis. It was found that hardness, gumminess and adhesiveness of all studied samples increased, while springiness and cohesiveness decreased during ripening. An increase of chewiness values during the first stages of ripening was observed, followed by a decrease to the 60th day. It was found that ripening time, as well as ripening temperature had a significant effect on the changes in Kashakaval texture parameters. Cheese samples ripened at higher temperatures had lower values for hardness, cohesiveness, gumminess and chewiness. Ripening temperature had no significant effect on the changes in springiness and adhesiveness of the studied samples. The results obtained showed that by an appropriate combination of the two factors, ripening time and temperature, the changes in the Kashkaval cheese texture can be controlled, which is important for the quality of the final product.

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Journal of Thermal Analysis and Calorimetry
Authors: W. Sułkowski, A. Danch, M. Moczyński, A. Radoń, A. Sułkowska, and J. Borek

Abstract  

Granulated rubber obtained from used tyres, below 1.5 mm granularity (fine rubber) and polyurethane prepolymers (Chemolan M, Chemolan M50 and Chemolan B3) were used for the synthesis of rubber waste-polyurethane composites, containing 90, 85, 80, 75 and 70%w/w of fine rubber. The influence of the kind of polyurethane resin on hardness, elasticity, glass transition temperature and thermal stability of composites was studied. Kinetic parameters of the thermal degradation process of composites were calculated from thermogravimetric analysis (TG) data.

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In this paper, the influence of two selected parameters (the welding time and the presence of the activating flux on the surface of the base metal) on the weld joint at Stud Arc Welding process is investigated. In the experimental part of the paper, the drawn arc stud welding process with the ceramic ferrule is applied with the different welding time and the application of the activating flux for ATIG process. In order to evaluate the influence of the welding time and the activating flux on the weld characteristics, the cast zone width and Vickers hardness HV 0.2 are measured.

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Abstract  

An alkyd/melamine resin mixtures are mainly used in industrial baking enamels. The aim of this work was to study the curing behaviour of alkyds based on dehydrated castor oil and soybean oil with melamine resin by differential scanning calorimetry (DSC). The kinetic parameters obtained by the transformation of dynamic DSC results into isothermal data through Ozawa kinetic model are in good agreement with those determined by the isothermal DSC experiments. The apparent degree of curing, determined by DSC measurements and sol/gel method, has a pronounced effect on the hardness of the resultant coating film.

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Abstract  

An ancient sword was examined for indications of forgery or, if authentic, any later processing or changes, e.g. replacement of parts of the weapon. Radiochemical as well as non-destructive analyses using high energy photon activation were used as analytical techniques. Metal parts of the hilt were analysed radiochemically and instrumentally whereas the blade was analysed non-destructively. Metallurgical investigations (hardness measurements, microstructure analysis) performed in parallel are also briefly described. No evidence of non-authenticity was found, which agrees well with the results of the stylistical and weapon-scientific investigation carried out by an expert of ancient weaponry.

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Kinetic parameters of decomposition of some selenites

Generalized perturbation theory of chemical reactivity

Journal of Thermal Analysis and Calorimetry
Authors: L Vlaev, V Georgieva, and S Genieva

Abstract  

Studying the kinetics of isothermal decomposition of thirteen selenites at isothermal heating, the values of activation energy E of the process, pre-exponential factor A in Arrhenius equation and changes of entropy for the formation of the activated complex of the reagent were calculated. Direct dependence between the thermal stability of the selenites and their cation radii on their 'hardness' or 'softness' was found. The dependence was interpreted in the terms of the generalized perturbation theory of chemical reactivity. Kinetic compensation effect was observed only for the selenites, which thermally decompose by the same mechanism.

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The enrichment of bread with wheat bran as a source of dietary fibre seems to be necessary for human health, because bread is the most consumed commodity in many countries. However, wheat bran has some adverse effects on the bread quality during storage. The aim of this study was to produce barbari bread with increased nutritional value and improved texture by the addition of coated wheat bran (0.67 and 1.34% based on flour stearic acid or St1, 2 and beeswax or Bw1, 2). Bread made from uncoated wheat bran was used as control. The least crust to crumb ratio was seen for control and Bw1. Water activity and moisture content results showed that the crumb of Bw1 and control had the better moisture retention during storage. Textural properties of samples showed that there were no significant differences in the hardness of the samples (P>0.05). However, the least increase in hardness during storage was observed for stearic acid coated samples. Other texture profile analysis parameters, such as cohesiveness and springiness, showed that Bw1 and Bw2 samples had no significant changes during storage. Differential scanning calorimetry (DSC) showed the least enthalpy for Bw1 after baking (385.21 J g–1) and during storage (567.62 J g–1). Accordingly, results showed that beeswax, especially at 0.67% (based on flour), is the best shell material for bran coating in order to improve bread texture and shelf life.

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