Index of epithelization rate of thermal burns in laboratory animals when application of the “acerbin” preparation

Thermal burns in animals represent an urgent problem for veterinary medicine, since the anti-burn drugs available on the world pharmacological market are not always adapted for use on animals and are approved for use in veterinary medicine. In this regard, the aim of the work was to use the wound healing spray “Acerbin” for medical purposes in the treatment of thermal burns and to evaluate its therapeutic efficacy by the rate of epithelialization of burn defects in the skin in laboratory animals. The work was carried out at the Department of Surgery and Therapy of the Kursk State Agricultural Academy, on laboratory white mice in the amount of 60 individuals, in which thermal burns were simulated in the croup and treated with applications of the Acerbin spray. To assess the rate of growth of epithelialization, planimetric measurements of the area of burns were carried out before treatment on the 3rd, 5th, 7th, 10th and 14th days of treatment, as well as the corresponding mathematical calculations of the rate of reduction of burn defects. According to the research results, it was found that when applying the Acerbin spray, the burn rate index on the 3rd day was 0.25 ± 0.06; on the 5th day 0.58 ± 0.03; on the 7th day 0.74 ± 0.01; on the 10th day 0.86 ± 0.02; on the 14th day 0.95 ± 0.01. Thus, at the end of the therapeutic period, the index of the epithelialization rate of thermal burns approached the most physiologically justified numerical expression equal to “1.0”, which allows it to be recommended for use in veterinary medicine as the preparation of choice for the treatment of thermal burns of the skin in animals.

Laboratory plant for evaluation of burnout rate of various materials

Описана методика исследования скорости выгорания различных материалов. Для реализации методики создана лабораторная установка. Экспериментально установлено, что процесс выгорания материалов зависит от температуры реактора и скорости воздушного потока. Кривая выгорания имеет S-образный вид и три характерных участка: индукционный период, линейный участок и участок реакции, где происходит выгорание углеродистого остатка. В табличной форме представлены результаты исследования некоторых широко распространенных материалов. The article describes a method for studying the burnout rate of various materials. There was created the laboratory plant for implementation of the method. It is experimentally established that the process of burnout of materials depends on the temperature of the reactor and the air flow rate. The burn-up curve has an S-shape and three characteristic sections: the induction period, the linear section, and the reaction section where the carbon residue burns out. The article presents the results of study of some widely distributed materials in tabular form. The mass burn rate of beech wood is 1.5 times higher than that one of pine. Perhaps this is due to the impregnation of beech with furniture varnish, since the sample was part of the furniture lining. It is noteworthy that significant discrepancy in the burn-up rates was obtained during combustion of samples of different brands of polyurethane foams. So, for hard polyurethane foam - “izolan 2”, which has a flame retardant in its composition, burnout curves with longer induction period are obtained (as a result of flame retardant action). However, the burnout rate is higher in comparison with soft polyurethane foam without flame retardant (foam rubber). The composition of the material “isolan-2”. Rubber also has a long induction period, but a high burnout rate.

A Benchmark Study of Burning Rate of Selected Thermites through an Original Gasless Theoretical Model

This paper describes a kinetic model dedicated to thermite nanopowder combustion, in which core equations are based on condensed phase mechanisms only. We explore all combinations of fuels/oxidizers, namely Al, Zr, B/CuO, Fe2O3, WO3, and Pb3O4, with 60 % of the theoretical maximum density packing, at which condensed phase mechanisms govern the reaction. Aluminothermites offer the best performances, with initiation delays in the range of a few tens of microseconds, and faster burn rates (60 cm s−1 for CuO). B and Zr based thermites are primarily limited by diffusion characteristics in their oxides that are more stringent than the common Al2O3 barrier layer. Combination of a poor thermal conductivity and efficient oxygen diffusion towards the fuel allows rapid initiation, while thermal conductivity is essential to increase the burn rate, as evidenced from iron oxide giving the fastest burn rates of all B- and Zr-based thermites (16 and 32 cm·s−1, respectively) despite poor mass transport properties in the condensed phase; almost at the level of Al/CuO (41 versus 61 cm·s−1). Finally, formulations of the effective thermal conduction coefficient are provided, from pure bulk, to nanoparticular structured material, giving light to the effects of the microstructure and its size distribution on thermite performances.

Examination of the effect of fire retardant materials on timber

PurposeThe fire safety of structures is an existing and important design aspect, which is assured by strict regulations. As a means to adhere to the strict requirements, fire protection has become a core problem. It is particularly difficult to comply with these regulations in the case of timber, which is a combustible material. These problems could be solved by enveloping the wood in fire retardant materials. MSZ EN 1995-1-2 currently does not take into consideration the fire-retardant materials charring rate under fire exposure.Design/methodology/approachHowever, currently these fire retardants are proving to be reliable and depending on their application can achieve better reaction-to-fire classifications. During the research, the authors used five different fire-retardant materials on three different types of wood and tested their behaviours in a laboratory. When selecting them, it was important to choose the species that are most commonly used in the building industry but which have significantly different densities. Our choice fell upon spruce (360 kg/m3), Scots pine (540 kg/m3) and oak (650 kg/m3). During the tests, we examined the weight reduction and the process of burning on the specimens treated with the fire retardant material. In addition, the authors also performed tests by derivatography on both untreated and treated specimen.FindingsThe question is whether the effects of the fire retardants should be taken into consideration when calculating the extent of the burn. The Eurocode (MSZ EN 1995-1-2) does not provide any opinions. On the market, there are manufacturers who are already discussing the possibilities of reducing the burn rate during the qualification of paints. In this paper, based on the results we received, we discuss the beneficial effects of the fire retardants which can be taken into account while measuring cross-sections.Originality/valueBy using fire retardants, a high proportion of cross-sectional area gain is only possible in case of small cross-sections; therefore, it is advisable to use them here as well. This can be effective for example in many smaller cross-sections, when there is a little space and therefore requires a small cross-section. Thus, if a larger cross-section without protection is not possible, it can be replaced by a smaller cross section, treated with a fire retardant.

Scale effects on hybrid rocket engine performance

In the current study, the effects of scaling up a hybrid rocket engine (HRE) in size has on its performance is investigated. A HRE design from a past RU study is selected as the base model to be progressively increased in size while geometric scale is maintained, up to ten times the original’s size. A computer program employing a quasi-steady convective heat feedback burn rate model is used to conduct simulated engine firings. One finding from this study is that the drop- off in performance for this engine, in going up in size, is not as much as expected. This can be attributed to a conservative oxidizer injection temperature setting in the model, and an oxidizer-fuel ratio mixture influence for this engine that is more impactful. The results presented here however do, to some degree, concur with established trends, with respect to thrust prediction, as the reference HRE is scaled up in size.