scholarly journals The Mechanism of Joint Reduction of MoO3 and CuO by Combined Mg/C Reducer at High Heating Rates

2021 ◽  
Vol 5 (12) ◽  
pp. 318
Author(s):  
Hasmik Kirakosyan ◽  
Khachik Nazaretyan ◽  
Sofiya Aydinyan ◽  
Suren Kharatyan
Keyword(s):  
Interaction Mechanism ◽  
Decisive Role ◽  
Isoconversional Method ◽  
Reducing Agents ◽  
Isothermal Treatment ◽  
Molybdenum Oxides ◽  
Heating Rates ◽  
High Heating ◽  
Combustion Processes

Understanding of the decisive role of non-isothermal treatment on the interaction mechanism and kinetics of the MoO3-CuO-Mg-C system is highly relevant for the elaboration of optimal conditions at obtaining Mo-Cu composite powder in the combustion processes. The reduction pathway of copper and molybdenum oxides with combined Mg + C reducing agents at high heating rates from 100 to 5200 K min−1 was delivered. In particular the sequence of the reactions in all the studied binary, ternary and quaternary systems contemporaneously demonstrating the effect of the heating rate on products’ phase composition and microstructure was elucidated. The combination of two highly exothermic and speedy reactions (MoO3 + 3Mg and CuO + Mg vs. MoO3 + CuO + 4Mg) led to a slow interaction with weak self-heating (dysynergistic effect) due to a change in the reaction mechanism. Furthermore, it has been shown that upon the simultaneous utilization of the Mg and C reducing agents, the process initiates exclusively with carbothermic reduction, and at relatively high temperatures it continues with magnesiothermic reaction. The effective activation energy values of the magnesiothermic stages of the studied reactions were determined by Kissinger isoconversional method.

scholarly journals The Mechanism of Joint Reduction of MoO3 and CuO by Combined Mg/C Reducer at High Heating Rates

2021 ◽  
Author(s):  
Hasmik Kirakosyan ◽  
Khachik Nazaretyan ◽  
Sofiya Aydinyan ◽  
Suren Kharatyan
Keyword(s):  
Interaction Mechanism ◽  
Decisive Role ◽  
Isoconversional Method ◽  
Reducing Agents ◽  
Conversion Degree ◽  
Molybdenum Oxides ◽  
Heating Rates ◽  
Composite Powders ◽  
Efficient Delivery ◽  
High Heating

Understanding of the decisive role of the interaction mechanism and kinetics in the combustion processes is highly relevant for the elaboration of optimal conditions for obtaining Mo-Cu composite powders. From this perspective, the efficient delivery of the reduction mechanism of copper and molybdenum oxides with combined Mg + C reducing agents at high heating rates is crucial to develop a valuable approach for the combustion synthesis of Mo-Cu composite powders. Herein, we shed light on the mechanism of the reactions in all the studied binary, ternary and quaternary systems contemporaneously demonstrating the effect of the heating rate on the conversion degree. The combination of two highly exothermic and speedy reactions (MoO3+3Mg and CuO+Mg vs MoO3+CuO+4Mg) led to a slow interaction with weak self-heating (dysynergistic effect) due to a change in the reaction mechanism. On the other hand, it has been shown that during the simultaneous utilization of the Mg and C reducing agents, the process begins exclusively with carbothermic reduction, and at relatively high temperatures it continues with magnesiothermic one. The effective activation energy values of the magnesiothermic stages of the studied reactions were determined by Kissinger isoconversional method.

scholarly journals Role of Semenov’s Theory of Chain Reactions in the Formation of Modern Concepts on the Processes of Combustion, Explosion, and Detonation of Gases

2021 ◽  
Vol 15 (2) ◽  
pp. 278-284
Author(s):  
V. V. Azatyan
Keyword(s):  
Flame Propagation ◽  
Chemical Reactions ◽  
Atmospheric Pressure ◽  
Chemical Control ◽  
Experimental Studies ◽  
Decisive Role ◽  
Chain Reactions ◽  
Self Heating ◽  
Combustion Processes

Abstract This paper presents the results of the theoretical and experimental studies of ignition, flame propagation, explosion, and detonation of gases, showing that, contrary to previous concepts, chain mechanisms in combustion reactions play a decisive role not only at pressures tens of times lower than atmospheric pressure in the absence of self-heating but also at higher pressures and any temperature conditions. Examples of the chemical control of all these processes are given. At the same time, the results show the outstanding role of N.N. Semenov’s theory of chain reactions in the development of the theory of the rates of chemical reactions and combustion processes.

scholarly journals Joint Reduction of NiO/WO3 Pair and NiWO4 by Mg + C Combined Reducer at High Heating Rates

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1351
Author(s):  
Marieta Zakaryan ◽  
Khachik Nazaretyan ◽  
Sofiya Aydinyan ◽  
Suren Kharatyan
Keyword(s):  
Composite Materials ◽  
High Speed ◽  
Synergetic Effect ◽  
Isoconversional Method ◽  
Heating Rates ◽  
Formation Pathway ◽  
High Heating ◽  
Functional Features ◽  
Maximum Temperatures ◽  
Solid Liquid

Functional features of Ni-W composite materials combined with successful performance enabled a breakthrough in their broad application. To disclose the formation pathway of Ni-W composite materials at extreme conditions of combustion synthesis in the NiO-WO3-Mg-C and NiWO4-Mg-C systems for the optimization of the synthesis procedure, the process was modeled under programmed linear heating conditions by thermal analysis methods. The reduction kinetics of tungsten and nickel oxides mixture and nickel tungstate by Mg + C combined reducer at non-isothermal conditions was studied at high heating rates (100–1200 °C min−1) by high-speed temperature scanner techniques. It was shown that when moving from low heating to high heating rates, the mechanism of both the magnesiothermic and magnesio-carbothermic reductions of the initial mixtures changes; that is, the transition from a solid-solid scheme to a solid-liquid scheme is observed. The strong influence of the heating rate on the reduction degree and kinetic parameters of the systems under study was affirmed. The simultaneous utilization of magnesium and carbon as reducers allowed the lowering of the starting and maximum temperatures of reduction processes, as evidenced by the synergetic effect at the utilization of a combined reducer. The effective values of activation energy (Ea) for the reactions proceeding in the mixtures NiO + WO3 + 4Mg, NiO + WO3 + 2.5Mg + 1.5C, NiWO4 + 4Mg and NiWO4 + 2Mg + 2C were estimated by Kissinger isoconversional method and were 146 ± 10, 141 ± 10, 216 ± 15 and 148 ± 15 kJ mol−1, respectively.

Comparing fast inductive tempering and conventional tempering: Effects on microstructure and mechanical properties

2018 ◽  
Vol 115 (4) ◽  
pp. 407 ◽  
Author(s):  
Annika Eggbauer Vieweg ◽  
Gerald Ressel ◽  
Peter Raninger ◽  
Petri Prevedel ◽  
Stefan Marsoner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Impact Energy ◽  
Charpy Impact ◽  
Heat Treating ◽  
Processing Route ◽  
High Heating Rate ◽  
Heating Rates ◽  
High Heating ◽  
Tempering Treatment ◽  
Carbide Distribution

Induction heating processes are of rising interest within the heat treating industry. Using inductive tempering, a lot of production time can be saved compared to a conventional tempering treatment. However, it is not completely understood how fast inductive processes influence the quenched and tempered microstructure and the corresponding mechanical properties. The aim of this work is to highlight differences between inductive and conventional tempering processes and to suggest a possible processing route which results in optimized microstructures, as well as desirable mechanical properties. Therefore, the present work evaluates the influencing factors of high heating rates to tempering temperatures on the microstructure as well as hardness and Charpy impact energy. To this end, after quenching a 50CrMo4 steel three different induction tempering processes are carried out and the resulting properties are subsequently compared to a conventional tempering process. The results indicate that notch impact energy raises with increasing heating rates to tempering when realizing the same hardness of the samples. The positive effect of high heating rate on toughness is traced back to smaller carbide sizes, as well as smaller carbide spacing and more uniform carbide distribution over the sample.

The main directions of educational policy of Finland

2020 ◽  
Vol 11 (2) ◽  
pp. 6-13
Author(s):  
K. E. Stupak ◽  
Keyword(s):  
Higher Education ◽  
Education Policy ◽  
Education System ◽  
Decisive Role ◽  
The State ◽  
Vocational Education And Training ◽  
State Education Policy ◽  
Role Of The State ◽  
State Education

The article deals with analyzing the main streams of the education policy in Finland, which reflect the relationship between a person and society in modern socio–economic conditions. Such policy directs the system of education to change the person and his mind himself. Finland using its education system, has long before been concerned about preparing people for the future by reforming approaches to teaching in schools and higher education institutions. As a result, it has achieved world–wide recognition and top positions in various ratings have resulted. Therefore, today there is a great interest of scientists in certain issues of education functioning in Finland. Thus, G. Androshchuk, V. Butova. I. Zhernokleeva, T. Pushkareva and others study in their works the purpose and decisive role of Finland's education policy in the development of the education system. S. Grinyuk and V. Zagvozdkin pay attention to the practical the steps of reforming the Finnish system of education. T. Drobyshevsk investigates the system of providing educational services in Finland as a sector of knowledge production. L. Volynets, P. Kukharchuk consider the principles of the state education policy of Finland. L. Smolskaya examines the role of the state policy in implementing the "Finnish phenomenon"; P. Basyliuk and Yu. Kulykova, focus attention on the study of the evolution of the system of higher education in Finland; O. Scherbak reveals peculiarities of vocational education and training.

Democratization in Serbia: An Analysis of Rational Choice and Structuralist Explanations

2015 ◽  
Author(s):  
Dunja Apostolov-Dimitrijevic
Keyword(s):  
Rational Choice ◽  
Path Dependence ◽  
Theoretical Perspective ◽  
Political Leadership ◽  
Decisive Role ◽  
The Other ◽  
Internal Factors ◽  
Transitional Societies ◽  
The Face

This paper explains political democratization in Post-Milosevic Serbia, utilizing two different accounts of the democratization process: one rooted in the rational choice framework and the other in structuralism. While rational choice explains the decisive role of political leadership in overcoming path dependence, the structuralist explanations show the transnational linkages that encourage democratization in the face of domestic setbacks. This particular debate between the two types of explanations represents the larger debate concerning the role of internal factors and external linkages in propelling democratization in transitional societies. The paper concludes by integrating the two sets of explanations offered by each theoretical perspective, in order to develop a coherent understanding of Serbia's democratization.   Full text available at: https://doi.org/10.22215/rera.v9i1.240

Controlled synthesis of functional Ag, Ag–Au/Au–Ag nanoparticles and their Prussian blue nanocomposites for bioanalytical applications

RSC Advances ◽  
2015 ◽  
Vol 5 (61) ◽  
pp. 49671-49679 ◽  
Author(s):  
Prem. C. Pandey ◽  
Richa Singh ◽  
Yashashwa Pandey
Keyword(s):  
Prussian Blue ◽  
Ag Nanoparticles ◽  
Active Role ◽  
Reducing Agents ◽  
Controlled Synthesis ◽  
Bioanalytical Applications

A facile method for the synthesis of functional AgNPs and bimetallic Ag–Au/Au–Ag are reported, enabling the formation of nanocomposite with prussian blue in a crystalline framework for bioanalytical applications, showing the active role of organic reducing agents and 3-aminopropyltrimethoxysilane.

scholarly journals Modulation of Macrophages M1/M2 Polarization Using Carbohydrate-Functionalized Polymeric Nanoparticles

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 88
Author(s):  
Raquel G. D. Andrade ◽  
Bruno Reis ◽  
Benjamin Costas ◽  
Sofia A. Costa Lima ◽  
Salette Reis
Keyword(s):  
Inflammatory Responses ◽  
Polymeric Nanoparticles ◽  
Interaction Mechanism ◽  
Mannose Receptor ◽  
The Body ◽  
Receptor Expression ◽  
Production Methods ◽  
Polymeric Nanocarriers ◽  
Efficient Delivery

Exploiting surface endocytosis receptors using carbohydrate-conjugated nanocarriers brings outstanding approaches to an efficient delivery towards a specific target. Macrophages are cells of innate immunity found throughout the body. Plasticity of macrophages is evidenced by alterations in phenotypic polarization in response to stimuli, and is associated with changes in effector molecules, receptor expression, and cytokine profile. M1-polarized macrophages are involved in pro-inflammatory responses while M2 macrophages are capable of anti-inflammatory response and tissue repair. Modulation of macrophages’ activation state is an effective approach for several disease therapies, mediated by carbohydrate-coated nanocarriers. In this review, polymeric nanocarriers targeting macrophages are described in terms of production methods and conjugation strategies, highlighting the role of mannose receptor in the polarization of macrophages, and targeting approaches for infectious diseases, cancer immunotherapy, and prevention. Translation of this nanomedicine approach still requires further elucidation of the interaction mechanism between nanocarriers and macrophages towards clinical applications.

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