INTERACTION OF IRON-CONTAINING NANOCLUSTER POLYOXOMETALATE WITH DOXORUBICIN

Актуальной проблемой в области адресной доставки лекарственных веществ являются аспекты, относящиеся к транспорту высокотоксичных препаратов, обладающих нежелательными побочными эффектами, в частности противоопухолевых. Были рассчитаны термодинамические параметры комплексообразования нанокластерного полиоксометаллата {MoFe}, перспективного в качестве средства адресной доставки лекарств, и широко применяемого в клинической практике цитостатика - доксорубицина. Взаимодействие доксорубицина с {Mo Fe} сопровождалось экзотермическим эффектом, что говорит об энергетически выгодном образовании комплекса. Кинетика процесса высвобождения доксорубицина из комплекса в буферном растворе с pH , соответствующим значению pH крови, была изучена методом люминесцентной спектроскопии. Были определены константы скорости процессов деструкции {Mo Fe} в комплексе, сопровождающейся высвобождением доксорубицина, и дальнейшего комплексообразования высвободившегося доксорубицина с продуктами распада {MoFe}. В будущем возможно управление скоростью высвобождения доксорубицина путем дополнительной стабилизации {Mo Fe}, например, путем его ассоциации с альбумином. Actual problem in the field of targeted drug delivery is transport of highly toxic drugs, with undesirable side effects, in particular antitumor medicine. The thermodynamic parameters of complexation between nanocluster polyoxometalate {MoFe}, promising as a means of targeted drug delivery, and a cytostatic agent - doxorubicin, widely used in clinical practice, were studied. The interaction of doxorubicin with {MoFe} was accompanied by an exothermic effect, which indicates an energetically favorable formation of the complex. The kinetics of the release of doxorubicin from the complex in a buffer solution with a pH corresponding to the pH value of blood was studied by fluorescence spectroscopy. The rate constants of destruction processes in the complex, accompanied by the release of doxorubicin, and further complexation of the released doxorubicin with decay products were determined. In the future, it is possible to slow down the release of doxorubicin by stabilizing the {MoFe}, for example, when it is associated with albumin.

Experimental Research on the Law of Energy Conversion during CO2 Sequestration in Coal

CO2 sequestration in coal is mainly attributed to adsorption. The adsorption experiments of CO2 were conducted at injection pressures ranging from 1 to 3 MPa on coal samples with five kinds of particle sizes. The fitting degree of four classical adsorption models to experimental adsorption data was systematically compared. The adsorption properties of CO2 were comprehensively discussed. The temperature changes of coal samples at different positions during CO2 adsorption were measured by using the improved adsorption tank, and then the energy conversion law was obtained. The results showed increasing gas injection pressure can effectively increase the adsorption capacity of CO2 on coal samples. The BET equation had the best fitting accuracy for CO2 adsorption on various size coal samples. There was a significant exothermic effect during CO2 adsorption and storage. With the rise of injection pressure, the peak value of the rising temperature of coal samples increased, but the change rate decreased. The maximum temperature rise of coal samples was up to 13.6 °C at 3 MPa, which should be of great concern for the prevention of coal spontaneous combustion. During the sequestration process of CO2, the adsorption resulted in a decrease in coal surface free energy and then partial conversion to heat, leading to the rise of coal temperature. In addition, the CO2 adsorption on the pore surface caused the expansion and deformation of coal.

Self-Heating Mould for Composite Manufacturing

The shipbuilding industry, engine manufacturing, aviation, rocket and space technology are promising fields of application for polymeric composite materials. Shape-generating moulding tools with internal heating are used for the creation of a more economically viable method of moulding of internally heated composite structures. The use of a fine-fibered resistive structure in the heated tools allows implementation of effective heating of the composite and elimination of the need for expensive and energy-intensive heating equipment. The aim of this paper was the reduction of energy consumption for internally heated moulding tools by choosing the optimal parameters for their resistive layer. A method for determination of the parameters of the moulding tool resistive layer was developed. This method allows calculation of the heating layer parameters and implementation of the specified time–temperature regime for moulding of the composite structure. It was shown that energy saving for the heated fiberglass shape-generating moulding tools was from 40 to 60%. It was found that the increase in the thickness of the moulded package of the polymeric composite material resulted not only in a higher supplied power for the heating system, but also in a complication of the method for system control, because of the growing exothermic effect of the binder curing reaction. For composite products based on Hysol EA 9396 binder, thicknesses more than 4 mm are critical, because it is not possible to cope with the self-heating effect only by cooling with ambient air already utilized at the twentieth minute of the moulding process. The influence of the physical and mechanical characteristics of the moulding tool material and stiffening ribs was analysed in terms of energy consumption and controllability of the heating system. Fiberglass shows the lowest energy consumption. Heating of the aluminium and steel moulding tools for the same purpose will require 20% and 45% more power, respectively. An increase in the number of stiffening ribs has a strong effect on the heat removal of the heating system. With a small number of aluminium ribs it is not possible to maintain the specified temperature–time regime for a fiberglass moulded package of 5 mm thick with the use of the equipment. However, when the number of stiffeners is increased to 10, the exothermic effect of the reaction becomes smoother and then the heating equipment can cope with the task. An experimental prototype of heating equipment of moulding tools for the manufacturing of structures of polymeric composite materials, as well as a flexible thermal blanket for repair of non-separable structures, were developed. The results can be the basis for a new method of optimal design of parameters of moulding tool structure at minimal heat removal to the environment.

Evolution of Microstructure in Friction Stir Processed Dissimilar CuZn37/AA5056 Stir Zone

Dissimilar friction stir processing on CuZn37/AA5056 was performed to study structural and phase evolution of a friction stir zone. Formation of 5–10 μm intermetallic compounds (IMCs) such as Al2Cu was the main type of diffusion reaction between copper and aluminum. Other alloying elements such as Mg and Zn were forced out of the forming Al2Cu grains and dissolved in the melt formed due to exothermic effect of the Al2Cu formation. When solidified, these Zn-enriched zones were represented by α-Al+Al2Cu+Zn phases or α-Al+Al2Cu+Zn+MgZn regions. Eutectic Zn+MgZn was undoubtedly formed the melt after stirring had stopped. These zones were proven to be weak ones with respect to pull-off test since MgZn was detected on the fracture surface. Tensile strength of the stirred zone metal was achieved at the level of that of AA5056.

Metallurgy and Mechanism of Underwater Wet Cutting Using Oxidizing and Exothermic Flux-Cored Wires

This paper considers the metallurgical processes of dissociation, ionization, oxidation, deoxidation, and dissolution of oxides during underwater wet cutting. A multiphase mechanism of underwater wet cutting consisting of working and idle cycles of the electrical process in a pulsating vapor gas bubble is proposed. A model of arc penetration into metal due to metal oxidation and stabilization of the arc by the inner walls of a narrow kerf is proposed. For underwater cutting of 10 KhSND, 304L steel, CuAl5, and AlMg4.5Mn0.7 alloy, we provide a principle of modeling the phase composition of the gas mixture based on high oxygen concentration, improving ionization, enthalpy, heat capacity, and thermal conductivity of plasma through the use of a mixture of KNO3, FeCO3, and aluminum. The method of improving the thermophysical properties and ionization of plasma due to the exothermic effect when introducing Fe3O4, MoO2, WO2 oxides and Al, Mg, Ti deoxidizers is proposed. Although a negative effect of refractory slag was revealed, it could be removed by using the method of reducing surface tension through the ionic dissolution of refractory oxides in Na3AlF6 cryolite. In underwater cutting of 10 KhSND and 304L, the steel welding current was 344–402 A with a voltage of 36–39 V; in cutting of CuAl5 and AlMg4.5Mn0.7 alloy, the welding current was 360–406; 240 A, with a voltage of 35–37; 38 V, respectively, with the optimal composition of flux-cored wire: 50–60% FeCO3 and KNO3, 20–30% aluminum, 20% Na3AlF6. Application of flux-cored wires of the KNO3-FeCO3-Na3AlF6-Al system allowed stable cutting of 10KhSND, AISI 304L steels, and CuAl5 bronze with kerf width up to 2.5–4.7 mm.

Improving the properties of plasma heat-resistant coatings by means of spraying materials that reacting with exothermic effects

The quality of heat-resistant coatings deposited by flame spraying is largely determined by the adhesion of the coating to the surface of the part. One of the ways to increase adhesion is to deposition intermediate layers of thermosetting powders between the base material and the coating. In this work, two versions of heat-protective coatings are investigated — a two-layer coating consisting of an Al – Ni sublayer (20 – 80 wt. %) and a main ZrO2 layer, and a single-layer coating sprayed from an aluminum-clad zirconium oxide powder (20 ZrO2 – 80 Al, wt. % ). The method of differential thermal analysis was used to determine the temperature ranges and values of the exothermic effects of oxidation and redox reactions during heating of Al – Ni and ZrO2 clad powders. A significant exothermic effect was found during oxidation of the aluminum cladding shell in the temperature range of 360 °C and a stronger thermal effect due to the redox reaction at a temperature of 920 °C. The microstructure and microhardness of the obtained coatings have been studied, and their thermal conductivity and adhesion have been assessed. The resistance of the coatings during thermal cycling tests has been determined. It has been established that thermal protective coatings made of aluminum-clad zirconium oxide powder have the best characteristics under thermal cycling conditions. A higher level of adhesion and thermal cyclic resistance of such coatings are due to an increase in the enthalpy of aluminum-clad ZrO2 powders due to exothermic reactions and the presence of a metal binder.

GEOLOGY OF CARBONACEOUS DEPOSITS OF THE BIRGILDA STRATA (EAST URAL TROUGH)

The article describes the geological structure of the Birgilda strata, which is widely developed in the East Ural trough. It is shown that the Birgilda black shales, which contain Corg in the range of 0.5–2.7% (average 1.3%), are of the low-carbon type. The exothermic effect in them occurred mainly in the temperature range 570–660 ° С, which corresponds to the greenschist facies of regional metamorphism. On the A-S-C diagram, the rocks of the Birgilda strata are approximately equally scattered over the carbonate-carbonaceous and siliceous-carbonaceous fields and noticeably less in the terrigenous-carbonaceous fields. The Birgilda sequence is characterized by a collisional environment of accumulation and products of destruction of mainly basic igneous rocks.

Vysokoteplotní fázové transformace kaolinitu v závislosti na krystalinitě

Although kaolinite is one the most important industrial minerals, the processes of its transformation to mullite have not been completely explained so far. The study is focused on kaolinite crystallinity calculation and its effect on high-temperature phases transitions in the series kaolinite-mullite. Samples of purified natural kaolins from several sites were analysed using X-ray diffraction (XRD). Besides the determination of the complex mineral composition, kaolinite crystallite size was calculated from XRD data by the Rietveld method, Scherrer equation and using the Hinckley crystallinity index. Thermal analysis (DSC/TG) was used as the principal approach to examine endothermic and exothermic effects of kaolinite transformations. The course and maximum temperatures of the observed effects were correlated with the original crystallite size of kaolinite. Two samples with different kaolinite crystallinity were also analysed by high-temperature X-ray diffraction (ht-XRD) to study the formation of mullite. Scanning electron microscope (SEM) was used to visualize morphology of kaolinite.It was found out that the original crystallinity of kaolinite affects all three examined processes-kaolinite dehydroxylation, formation of crystalline phases from metakaolinite and development of mullite crystal structure. Dehydroxylation of samples with higher kaolinite crystallinity takes place at higher temperatures. Similar effect applies for the reaction(-s) at the temperature about 980 °C observed at heat flow curve where crystallization of spinel type phase and mullite with very low crystallinity occurs. Broadening of FWHM of the exothermic effect points to decreasing kaolinite crystallinity. Crystallization of mullite exhibits different dependence on kaolinite crystallinity than the previous processes. The results show that mullite with larger crystallite size develops faster from kaolinite of low crystallinity and vice versa.

TiAl-Based Materials by In Situ Selective Laser Melting of Ti/Al Reactive Composites

Additive manufacturing (AM) of refractory materials requires either a high laser power or the use of various easily melting binders. In this work, we propose an alternative—the use of spherical reactive Ti/Al composite particles, obtained by preliminary high-energy ball milling. These powders were used to produce high-temperature TiAl-based materials during the selective laser melting (SLM) process. When laser heating is applied, mechanically activated composite particles readily react with the release of a considerable amount of heat and transform into corresponding intermetallic compounds. The combustion can be initiated at relatively low temperatures, and the exothermic effect prevents the sharp cooling of as-sintered tracks. This approach allows one to produce dense intermetallic materials with a homogeneous structure in one step via SLM and eliminates the need for powerful lasers, binders, or additional post-processing and heat treatments.