Optimal Chemical Composition Research Articles

Study of the critical deformation dependence for dynamic recrystallization in low-carbon steels on the chemical composition

The article considers dependence of the critical deformation for dynamic recrystallization in low-alloy steels on the chemical composition. The article shows an improved model for forecasting the critical deformation for dynamic recrystallization, which allows considering the content of chemical elements in steel. The article analyzes the influence of the chemical composition of low-alloy steels on the value of critical deformation during hot deformation. The article shows that the developed mathematical model can be used in the system of automated control of the structure and properties of steels during hot rolling to forecast conditions for the development of dynamic recrystallization and to select the optimal chemical composition of steels.

Solution-deposited and low temperature-annealed Eu3+/Tb3+-doped CaMoO4/SrMoO4 luminescent thin films

Eu3+/Tb3+-doped CaMoO4/SrMoO4 luminescent thin films were deposited by a facile solution method, and were annealed over the temperature range of 350–650 °C. Luminescent thin films were characterized by means of X-ray diffraction (XRD), photoluminescence (PL), UV–vis absorption, scanning electron microscope (SEM) and energy disperse spectroscopy (EDS). In addition, the effects of alkali metal ions (Li+, Na+ and K+) on the luminescence properties of CaMoO4/SrMoO4 thin films were systematically investigated. We found that the optimal chemical compositions for the luminescent molybdate thin films are Ca0.87MoO4:Eu3+ 0.10, K+ 0.03, Sr0.82MoO4:Eu3+ 0.15, K+ 0.03, Ca0.87MoO4:Tb3+ 0.03, Li+ 0.1, and Sr0.82MoO4:Tb3+ 0.15, Li+ 0.03.

Comparative Technological Characteristic of the Aligote 61-6 and Aligote N 10 Clones, Cultivated in the Soil and Climatic Conditions of the Region of Pleven

Abstract In the period 2011–2013 a technological characteristic of the Ukrainian clone Aligote 61-6 was made at the Institute of Viticulture and Enology – Pleven. The Bulgarian candidate-clone Aligote N 10 was used for control. During the grapes ripening, the dynamics of sugar accumulation was monitored. Upon technological maturity the indicators of the yields were accounted and mechanical analysis was performed. The chemical composition of the must, the obtained wines and their organoleptic qualities were analyzed. In its mechanical composition, Aligote 61-6 was typically wine one and it did not differ significantly in the texture and structure of the cluster and berry from the control. The theoretical yield of both clones was high. They exhibited good sugar accumulation and similar acid content. Grapes from the control had better technological indicators for obtaining wines of optimal chemical composition and quality. In the 2011 and 2013 vintages, the control wines exceeded those of the Ukrainian clone in terms of sugar-free extract content. The experimental wines Aligote N 10 had higher titratable acidity compared to the Ukrainian clone. The difference in the phenolic substances ratio and the colour intensity in the samples from both clones were insignificant. The control wines were superior in their organoleptic qualities to those of the Ukrainian clone.

Evaluating the effect of seven plant essential oils on pollen beetle (Brassicogethes aeneus) survival and mobility

Plant essential oils (EOs) represent an area of interest for managing agricultural pests. We examined the insecticidal efficacy of seven plant EOs on the survival and mobility of the pollen beetle Brassicogethes aeneus, a primary pest of oilseed rape (Brassica napus) in Europe. Topical dosing tests showed the EO of the inner bark of Cinnamomum verum (cinnamon) to be the most effective EO examined in our study. Subsequent bioassays, exposing B. aeneus to oilseed rape plant surfaces sprayed with various concentrations of C. verum EO, additionally suggested a concentration threshold at which this EO may significantly control B. aeneus populations. We suggest that further studies on B. aeneus examine the effect of certain pure compounds associated with the most promising EOs (individually as well as in binary combinations) in order to reveal optimal chemical composition and ratios to exploit within a B. aeneus management framework.

Effect of glass transition: density and thermal conductivity measurements of B2O3

The role of B2O3 as a fluxing agent for developing fluoride-free fluxes has been accentuated in recent years. Therefore, knowledge about the thermophysical properties of the oxide is essential to find the optimal chemical composition of the mold fluxes. In the present study, the density and thermal conductivity of B2O3 were measured by means of the buoyancy method, the maximal bubble pressure (MBP) method and the hot-wire method in the temperature range of 295 – 1573 K. The results are discussed in the context of the chemical stability of the B2O3 as well as the effect of glass transition on the thermal conductivity. The density of the B2O3 decreases non-linearly with increasing temperature in the temperature range of 973 – 1573 K. The MBP method was successfully applied for the density measurements with a viscosity up to 91 Pa.s. The thermal conductivity of the B2O3 in the solid and molten states increases with increasing temperature. Based on the Kittel’s equation, the temperature dependence of the thermal conductivity through the glass transition temperature of B2O3 was discussed.

Influence of alkali lactates on hydration of supersulfated cement

Supersulfated cement (SSC) is potentially an environmentally attractive alternative to portland cement for use in concrete as it is mainly composed of industrial by-product granulated iron blast-furnace slag and calcium sulfate, with only a small amount of alkali activator. The low-alumina content (<11%), slags produced in North American blast furnaces do not possess the optimum chemical composition for strength development when used in SSC. The main purpose of this study was to investigate the activation of low-alumina slag to increase its potential usefulness in SSC. To improve the performance of low-alumina slag in SSC, the influence of lactic acid salts such as Na and K-lactate were examined and proved to be an effective activation technique for improving the compressive strength of SSC mixtures.

Water filter with central perforated pipe for livestock complexes

Improving the livestock sector is a priority for the development of agricultural production in the Russian Federation. The development of animal husbandry to a certain extent depends on the use of clean drinking water. The use of contaminated drinking water for animals and birds leads to the accumulation of harmful and toxic substances in meat, milk and eggs. The use of such products by people significantly affects their health, leads to various diseases and shortens life expectancy. To filter water from various impurities, slotted filters are used in livestock complexes that do not provide high-quality water purification. A prototype of a filter for water purification with a central perforated pipe with a productivity of 5 m3/h with an increased service life of the filter bag has been developed. The developed filter provides water purification from high concentration of salts of iron, manganese, chlorine, hardness salts, hydrogen sulfide, pesticides, and also various organic compounds. The purified water is clean and transparent, has a pleasant taste, contains the optimal chemical composition of various impurities, does not contain pathogens and helminth eggs, and therefore meets the high sanitary and hygienic requirements for the safe drinking water for farm animals in the water treatment line of the livestock complex. It can also be used in chemical water treatment units of thermal power plants and other organizations.

Development of Modeling Algorithm of the Characteristics of the Steels in the Subsystem of Management of the Production Resources of Steel Production

The article is devoted to the development of an algorithm for modeling the characteristics of steels in accordance with customer requirements. A mathematical model is presented that takes into account the optimal levels of the main factors and their interaction, providing the required values of the characteristics. The next step in the study of the mathematical model was modeling by means of functional modeling methodology IDEF0. Input and output data, as well as normative documents of model management and mechanisms of this management for building a functional model are defined. The control mechanism was the software product OptimalSostav, developed using the object-oriented programming language Delphi. The software product is designed to simulate the characteristics of steels using the specified limits of permissible minimum and maximum values of mechanical properties. The algorithm of realization of the control mechanism, which is based on the fractional factor analysis, is described. The presented algorithm allows to identify the influence of chemical composition on the mechanical properties of steels in the form of mathematical and graphical dependencies and to determine the specified mechanical properties that meet the requirements of the customer. The main possibilities and the scope of the software product, which allows to solve the problem of predicting the optimal chemical composition, providing the required mechanical characteristics, as well as to adjust the process of steel melting within a given chemical composition to achieve the desired set of properties. The application of the software product on the example of the analysis of the influence of chemical elements on the mechanical properties of 75HMF roll steel is shown. The results of modeling in the form of mathematical and graphic dependences are given and the estimation of efficiency of application of the software product is given. The results of solving the problem of approximation of the obtained graphic dependences of the influence of chemical elements on the mechanical properties of the studied steel grade by means of Microsoft Excel are presented. It is established that the developed mathematical and algorithmic software of the software product allows to study the percentage of chemical elements in relation to the total composition of the alloy, based on the obtained pie charts and dependency graphs. The adequacy of the model is confirmed by experimental results.

IMPROVING THE MECHANICAL PROPERTIES OF THE IRON PARTS OF ICE BY THE METHOD OF COMPLEX DOPING

The article presents the results of long-term studies on the preparation of ligatures for gray and high-strength cast iron, which are used for the casting of key parts of internal combustion engines (ICEs). The main purpose of the study is to extend the life of the components of the ICE by increasing the wear resistance of the main parts (cylinder liners and piston rings). The objectives of the study are to develop a ligature and technology for gray and high-strength pig-iron. The research methods included mathematical modeling by means of regression analysis of Gram matrices formed on the basis of the determined correlation coefficients between the wear resistance of cast iron and its chemical composition, which was checked by Fischer's criterion, as well as practical studies on the casting of pig iron of various brands and bench tests of engines with parts on their basis. The regression equation describing the optimal chemical composition of cast iron is given as I = 8.4 +0.9C- 0.6Si - 3.2Mn - 84.4P - 4.5Ti - 33.8S + 9.3Cr + 0.4Ni - 5 , 9Cu - 1,1V + 24,3Mo. The basis for the development was the analysis of a sufficient number of literary sources related to the dopant properties of different elements when applied in gray and high-strength pig-iron. The main results of the literary search are presented in the corresponding section, where doping with nickel, chromium, molybdenum, vanadium, copper, silicon, titanium and other elements is covered. It was developed and protected by patents of Ukraine No. 25099 and number 25100 highly effective ligatures for pig-iron parts of cylinder-piston group (CPG). The bench tests of hardness resistance of the received pig-iron showed that the formation of sorbitol perlite due to alloying of pig iron in the ladle is an optimal approach that in combination with other measures can significantly improve the quality of the obtained parts. Thus, studies have shown that for super-loaded parts of the cylinder-piston group, the inevitable transition to doped pig-iron is inevitable. For pig-iron for bushings of cylinders of diesel engines of type ЧН 25/34 it is connected with their transition to high-grade fuel, and the work of new forced engines 6CHN 26/34 without doped pig-iron was not possible.

Ferroelastic properties and compressive stress-strain response of bismuth titanate based ferroelectrics

Ferroelectric materials have been widely studied for applications in numerous devices due to their controllable ferroelectric/ferroelastic properties under electric field or mechanical stress. Recently, a type of bismuth layer-structured ferroelectrics, W/Cr co-doped BIT ceramics, has attracted much attention due to its high Curie temperature, large spontaneous polarization, and particularly enhanced ferroelectric properties. Nevertheless, as a significant consideration for the reliability and durability of devices, the mechanical properties associated with ferroelastic behaviors of this type of ceramics are generally ignored. In this study, a type of W/Cr co-doped BIT ceramics with optimal chemical composition of Bi4Ti2·95W0·05O12.05+0.2 wt% Cr2O3 (BTWC) was synthesized via the solid-reaction technology. Ferroelastic domain structures and ferroelastic switching behaviors together with mechanical failure properties of the sintered ceramics were investigated in details. PFM observations reveal the existence of pseudo-90° and -180° ferroelastic domain structures in BTWC ceramics. The nonlinear deformation of stress-strain curve originates from ferroelastic domain switching induced by mechanical stress of sufficient magnitude. Moreover, the ferroelastic switching plays a significant role in improving the fracture toughness of BTWC ceramics. Additionally, the ceramics sintered at higher temperature are expected to exhibit a better ferroelastic switching behavior yet lower failure stress. The work can provide design consideration of loading conditions for practical applications of BTWC ceramics.

Performance optimization of Co2O3-PVDF-CNT-based supercapacitor electrode through multi-response optimization method

Taguchi optimization technique is used for obtaining optimal chemical composition of active materials to achieve maximum specific capacitance and minimum ESR for cobalt oxide-based electrode for supercapacitor. The study is based on interaction effect of three control factors which are mass loading of Co2O3, PVDF and MW-CNT, respectively. A regression model equation is also developed and validated experimentally. Optimum level of the control factors for maximum specific capacitance is found as Co2O3-40%, PVDF-10%, and MWCNT-30% and for minimum ESR is found as Co2O3-40%, PVDF-20%, and MWCNT-5%, respectively. The results can lead to new insights into development of supercapacitors with enhanced performance.

Effect of Chemical Composition of Zeolite Catalysts on Their Catalytic Properties in Isobutane Alkylation with Butylenes

The effect of the chemical composition of zeolite catalysts in the CaLaHX form on their catalytic properties in isobutane alkylation with butylenes have been studied. Optimum concentrations of metal oxides providing a butylene conversion of 97–100 wt %, an alkylate yield that is close to the theoretical value (95–100 wt %), and a trimethylpentane (TMP) selectivity at a level of 73 wt % have been determined (wt %: Na2O, 0.5; CaO, 0.6; La2O3, 18.3). It has been found that there is a fair good correlation between the optimum chemical composition of the catalyst samples and their acidity determined by temperature-programmed desorption of ammonia.

OPTIMIZATION OF THE COMPOSITION OF THE ELECTRICAL CONDUCTING LUBRICATING COMPOSITION FOR OPERATING APPLICATION IN THE BATTERY-BRUSH ASSEMBLY OF THE ELECTRIC MOTOR

A large number of methods for improving the efficiency of collector-brush units, a common feature of which is the creation of thin transition layers on the contact surface of materials that do not affect the current flow in contact and reduce the intensity of mechanical wear, have been studied. The data obtained in the course of the work showed that the electrically conductive lubricant composition helps to reduce the coefficient of friction to increase the wear resistance of the brush material and improve the switching conditions of the entire collector-brush unit. Considered the issue of optimization of the composition of the electrically conductive lubricating composition to the collector-brush Assembly of a traction motor. Providing with minimal costs the required composition of the conductive lubricant composition that meets the operating conditions is a difficult task and depends on a number of parameters of the components used. By using the generalized parameter of optimization of the desirability function of E. Harrington the optimal chemical composition of the conductive lubricant composition is obtained. Application of method E. Harrington to optimize the composition of the lubricant composition, allowed to meet the antagonistic requirements for its composition by mechanical and electrical characteristics, which had a positive impact on improving the performance and reliability of not only the collector-brush unit, but also the entire traction motor of the locomotive in operation.

Effect of Chemical Composition of Tetraethoxysilane and Trimethoxy(Propyl)Silane Hybrid Sol on Hydrophobicity and Corrosion Resistance of Anodized Aluminum

The current study indicates the application of three different range of hybrid sols on substrates. The aim was to achieve an optimum chemical composition on the silane- treated surface in terms of hydrophobicity and corrosion resistivity. Two different monomers including Tetraethoxysilane (TEOS) and Trimethoxypropylsilane (TMPSi) formed the hybrid sols. Sol-gel route was selected to enhance the corrosion resistance of the substrate (anodized aluminum). The role of the precursor’s molar ratios on the hydrophobicity was studied using static Water Contact Angle (WCA) and surface Roughness measurement (Ra). Owing to the evaluation by Field Emission Scanning Electron Microscopy (FESEM), a relatively smooth surface was revealed by silane-treated sample with TEOS: TMPSi, 1:0.5 M ratio. The sample prepared by TEOS: TMPSi, 0.5:1 M ratio sol illustrated a higher static water contact angle. To determine the corrosion resistance of the samples, Potentiodynamic Polarization, Open Circuit Potential (OCP) and Electrochemical Impedance Spectroscopy (EIS) measurements were performed using a 3.5% NaCl solution. Samples also were evaluated by Scanning Electron Microscopy (SEM) after seven days immersion in the same condition. According to EIS results, the sample treated in TEOS: TMPSi, 0.5:1 M ratio sol revealed the best corrosion resistance properties and minor deterioration of surface through the SEM micrographs.

A practical bio-based reversible permeability control for saturated sands

There is a need for an eco-friendly in situ reversible permeability control that reduces the number of artificial materials used to achieve a saturated sand layer. This study investigates such a control using a method that causes calcite precipitation and decalcification based on the metabolism of carbon sources. This generates carbon dioxide and organic acid and creates and detaches a biofilm using dry yeast and sodium hypochlorite. A pilot test determined the optimal chemical composition for this from a few different concentrations of carbon sources that begin the permeability reduction and recovery process. Following this, the main test (the permeability test) was conducted on a water sample taken from an agricultural area, which was combined with chemicals and dry yeast in a permeameter column. Permeability tests were carried out under three conditions (untreated, treated and treated combined with a biofilm detachment phase). The results suggest that (a) calcite precipitation induced by microbes, combined with bioclogging, can control the reduction in soil permeability and (b) a biofilm remover (sodium hypochlorite) and decalcification based on the organic acid created from the metabolism of carbon sources effectively recover the soil permeability to its initial state.

Phase diagram of NaFeyCo1-yO2 and evolution of its physico- and electrochemical properties with changing iron content

In this paper series of novel NaFeyCo1-yO2 (y = 0.1–1) cathode materials were synthesized and studied in terms of their structural properties, electrical conductivity and electrochemical performance in Na/Na+/NaxFeyCo1-yO2 cells. The materials were fabricated by a high-temperature solid-state reaction. XRD measurements with Rietveld analysis confirmed the presence of an O3-type phase with R-3m symmetry for all compositions with the existence of the monophase region within 0.3 ≤ y ≤ 0.7 Fe substitution range. The linear variation of the unit cell parameters of the R-3m structure was found for the broad Fe concentration. The combined studies of thermogravimetric analysis, XPS and Mössbauer spectroscopy pointed at the formation of the oxygen vacancies along with spontaneous magnetization at low temperatures. The electrical conductivity of the NaFeyCo1-yO2 exhibits thermally activated character with low activation energies and decreases with the increasing of iron content. Electrochemical investigation of Na/Na+/NaxFeyCo1-yO2 revealed changes in the character of discharge curve as a function of iron content and enabled us to select the NaFe0.3Co0.7O2 as a material exhibiting optimal chemical composition assuring high, stable discharge capacity (180 mAh g−1) along with high operational potential. The EIS and GITT studies were performed in order to investigate the kinetics of the electrode processes. The relation between sodium diffusion coefficients and chemical composition confirmed enhanced performance in case of the NaFe0.3Co0.7O2 material.

Behaviour of Alloy 617 OCC Under Hot Corrosion Conditions Encountered in Boilers in A-USC Power Plants

Superheater and reheater tubing constitute very critical parts of the boilers operating in advanced ultra-supercritical (A-USC) power plants. They are subjected to severe hot corrosion conditions during operation. The operating temperature and pressure in these power plants are very arduous, and materials with high resistance to hot corrosion and creep are required to produce the said tubing. Increased use of superalloys comes into picture in A-USC power plants, because of the demanding operating conditions prevailing there. Inconel 617 has been a superalloy developed for use in the form of superheater and reheater tubing seen in the power plants operating in A-USC environments. There have been researches aiming at improving its creep resistance, and versions with optimum chemical composition have been developed. Alloy 617 OCC, an optimized version of the superalloy 617, has been produced as a candidate material for superheater and reheater tube manufacturing in the context of development of A-USC power plant technology in India. However, hot corrosion issues are equally important for such applications. In light of the foregoing, studies have been carried out to analyse the performance of Alloy 617 OCC in hot corrosion conditions in simulated A-USC power plant environments. Oxidation tests for the alloy were conducted in the laboratory air environment under identical temperature/time conditions for the sake of comparison. Hot corrosion process was examined using thermo-gravimetry, and the corrosion products were characterized using a variety of material characterization techniques. The study reported the comparative corrosion performance of the superalloy in the two environments.

Effect of yttrium addition on microstructures, damping properties and mechanical properties of as-cast Mg−based ternary alloys

In order to reveal the functions of yttrium addition on damping and mechanical properties for Mg−based alloys, the damping and mechanical properties of prepared as-cast Mg−0.6Zr−xY ternary alloys with [Y] = 1.0, 2.0, 3.0, 4.0 and 5.0 mass % have been experimentally measured and theoretically explained through combining the observed microstructures with related theoretical models or mechanisms. The experimental results indicate that added [Y] in the ternary alloys has clear effect on grain refinement. Changing [Y] from 1.0 to 5.0 mass % can effectively decrease the average size of formed equiaxed α−Mg grains from 70.15 to 33.62 μm. The bulk-shaped yttrium-rich phase in α−Mg matrix is mainly composed of Mg24Y5 phase. Increasing [Y] from 1.0 to 5.0 mass % can significantly affect damping properties described by tanφ under the condition of ε > εcr = 2.0 × 10−2, while no visible effect of increasing [Y] on tanφ at ε < εcr = 2.0 × 10−2 can be obtained. Furthermore, the influence of changing strain ε from 1.0 × 10−4 to 1.0 × 10−1 on tanφ complies with dislocation pinning theory or the G−L model. Meanwhile, increasing [Y] in the ternary alloys shows the similar variation tendency for relationship between tanφ and temperature T from ambient temperature Tam to 673 K (400 °C). The effect of varying temperature T from Tam to 673 K (400 °C) on tanφ for the ternary alloys can be well explained by the grain boundary damping mechanism. In addition, increasing [Y] from 1.0 to 4.0 mass % can effectively promote both yield strength Rp0.2 and ultimate tensile strength Rm, however further increasing [Y] from 4.0 to 5.0 mass % cannot result in an obviously increasing tendency for Rp0.2 and Rm. The similar results of adding [Y] on elongation A can also be obtained with [Y] = 3.0% as a criterion. Meanwhile, the measured results of adding [Y] on Rp0.2 and Rm for the ternary alloys can be well explained by the grain boundary strengthening and solid solution strengthening mechanisms. Therefore, the optimal chemical composition for as-cast Mg−Zr−Y ternary alloys with higher damping properties and greater tensile properties is recommended to be Mg−0.6Zr−4.0Y.

Blood-brain barrier pericytes as a target for HIV-1 infection.

Pericytes are multifunctional cells wrapped around endothelial cells via cytoplasmic processes that extend along the abluminal surface of the endothelium. The interactions between endothelial cells and pericytes of the blood-brain barrier are necessary for proper formation, development, stabilization, and maintenance of the blood-brain barrier. Blood-brain barrier pericytes regulate paracellular flow between cells, transendothelial fluid transport, maintain optimal chemical composition of the surrounding microenvironment, and protect endothelial cells from potential harmful substances. Thus, dysfunction or loss of blood-brain barrier pericytes is an important factor in the pathogenesis of several diseases that are associated with microvascular instability. Importantly, recent research indicates that blood-brain barrier pericytes can be a target of HIV-1 infection able to support productive HIV-1 replication. In addition, blood-brain barrier pericytes are prone to establish a latent infection, which can be reactivated by a mixture of histone deacetylase inhibitors in combination with TNF. HIV-1 infection of blood-brain barrier pericytes has been confirmed in a mouse model of HIV-1 infection and in human post-mortem samples of HIV-1-infected brains. Overall, recent evidence indicates that blood-brain barrier pericytes can be a previously unrecognized HIV-1 target and reservoir in the brain.

High-Performance Li-Rich Layered Transition Metal Oxide Cathode Materials for Li-Ion Batteries

New stoichiometric Li-rich layered oxides (xLi2MnO3·(1-x)LiMn0.5Ni0.25Co0.25O2 or Li[LiyMn1-y-2zNizCoz]O2) were proposed as high-energy density cathode materials for Li-ion batteries. The correlation between chemical composition of the materials and their structural as well as electrochemical performances is discussed. It was found that all synthesized materials crystalize within C2/m space group with existence of superstructure and possess nanometric spherical-shaped morphology. The analysis of the charge/discharge tests shows that Li[Li0.2Mn0.6Ni0.1Co0.1]O2 electrode delivers nearly 350 mAh·g−1 for the first discharge process and 250 mAh·g−1 for following cycles. The investigation of the kinetics of the electrode reactions by means of CV and EIS methods confirmed that Li[Li0.2Mn0.6Ni0.1Co0.1]O2 exhibits highest lithium diffusion coefficients, what with obtained electrochemical cycling tests suggest optimal chemical composition of this material ensuring high energy density along with long-term endurance.