Mechanical properties, biodegradation, and biocompatibility of ultrafine grained magnesium alloy WE43

In this work, the effect of an ultrafine-grained (UFG) structure obtained by multiaxial deformation (MAD) on the mechanical properties, fatigue strength, biodegradation, and biocompatibility in vivo of the magnesium alloy WE43 was studie

Optimization of Nanostructuring Burnishing Technological Parameters by Taguchi Method

On the basis of application of Taguchi optimization method, an approach for researching influence of nanostructuring burnishing technological parameters, considering the surface layer microhardness criterion, is developed. Optimal values of burnishing force, feed and number of tool passes for hardened steel AISI 420 hardening treatment are defined

Stability of Heat and Energy Characteristics of Refrigerating Units as a Condition of Quality Increase of Agricultural Production Storage

This article provides information about the importance of stable thermal operating modes of refrigeration machines in the condition of changes in the thermal load on the compressor. We also consider the problem of the minimum energy consumption of refrigeration machines. These two parameters characterize the storage quality of agricultural products in refrigeration machines. It is shown that the temperature stability of the cooling chambers and the minimum energy consumption of the cooling process determine the refrigerator efficiency and, ultimately, the production cost. The article proposes continuous monitoring of the heat and energy indicators of refrigerators. These indicators are recorded and after the set period of operation, control and verification measurements of the control refrigeration machine’s heat and energy indicators are performed. The convergence or divergence of these indicators is used to evaluate the stability of the cooling chambers’ temperature regimes and the specific energy consumption. We also consider the influence of time on the performance of the compression refrigeration machine changes and methods of current technical condition diagnostics. If the deviations are insignificant, the program goes through the cycle to the beginning of monitoring and after a set period of time again automatically performs control measurements and evaluation of deviations. In the case of significant deviations, the decision-making subroutine is activated: either to operate the refrigerator further; perform its maintenance; suspend its operation; or replace it. Keywords: refrigeration units, cooling, heat and power characteristics, management controller, storage quality of agricultural productio

Students' individual work on studying the discipline «Mathematics Teaching Methodology» by using distance technologies

© 2017. revistaESPACIOS.com. The urgency of the problem set in the article is stipulated by the fact that over the recent years the role of information technologies in organizing students' individual work has strengthened. In this context, it is necessary to provide the educational process with electronic educational resources. The aim of the article is to organize individual work of students and to estimate its efficiency when mastering the discipline "Mathematics Teaching Methodology" by using distance technologies. The leading methods in researching this problem include the method of design aimed at selecting and structuring the content of the electronic resource, as well as testing according to the estimation of the performed work efficiency. The developed resources include all required components for organizing and carrying out the students' individual work: study, control, and correction. The experiment made by teachers of the Elabuga Institute of the Kazan (Volga Region) Federal University and related to implementing the developed electronic resources in the educational process showed the importance and efficiency of applying distance technologies in organizing individual work of students

Optimization of Nanostructuring Burnishing Technological Parameters by Taguchi Method

On the basis of application of Taguchi optimization method, an approach for researching influence of nanostructuring burnishing technological parameters, considering the surface layer microhardness criterion, is developed. Optimal values of burnishing force, feed and number of tool passes for hardened steel AISI 420 hardening treatment are defined

Опыт создания личного кабинета студента – личной электронной библиотеки в РГАУ-МСХА им. К. А. Тимирязева

The article is devoted to the currently topical topic of using the electronic library system by means of creating a student's personal account – a personal electronic library. The problem of using information technologies to provide students with high-quality educational information is currently coming to the fore due to the emergence of a large flow of information and the lack of criteria for its selection among students. The purpose of the publication is to acquaint readers with the results of work on the development of a personal electronic library of a university student, to provide students with educational materials in full, as well as with the results of a study of the effectiveness of using a personal account in the process of teaching students. To achieve this goal, the authors carried out experimental work, consisting of three modules: basic, theoretical and intellectual, as well as experimental work to establish the influence of the developed personal electronic library on the level of educational motivation of students, as well as its relationship with academic performance. The results of the study show that the use of a personal electronic library increases the educational motivation of students to study the subject, and also positively affects the academic performance of students, improving the quality of education. The practical significance of the work lies in the creation of a student's personal electronic library based on the electronic library system of the RSAU-Moscow Agricultural Academy named after K. A. Timiryazeva, which can be used in teaching university students.Статья посвящена использованию электронно-библиотечной системы с помощью личного кабинета студента – личной электронной библиотеки. В связи с появлением большого потока информации и отсутствием у студентов критериев её отбора проблема использования информационных технологий для обеспечения обучающихся качественной учебной информацией выходит на первый план. Статья знакоимт с результатами разработки личной электронной библиотеки, обеспечивающей студентов учебным материалом в полном объёме, а также с исследованием эффективности использования личного кабинета в процессе обучения. Авторы провели экспериментальную работу, состоящую из трёх модулей: базового, теоретического и интеллектуального, а также установили влияние личной электронной библиотеки на уровень учебной мотивации студентов и успеваемости. Результаты исследования показали, что личная электронная библиотека повышает учебную мотивацию студентов, положительно влияет на их успеваемость, повышая качество образования. Практическая значимость работы заключается в создании личной электронной библиотеки студента на базе электронно-библиотечной системы РГАУ-МСХА им. К. А. Тимирязева. Библиотека студента может использоваться при обучении студентов вуза

The effect of equal-channel angular pressing on microstructure, mechanical properties, and biodegradation behavior of magnesium alloyed with silver and gadolinium

The effect of equal channel angular pressing (ECAP) on the microstructure, texture, mechanical properties, and corrosion resistance of the alloys Mg-6.0%Ag and Mg-10.0%Gd was studied. It was shown that ECAP leads to grain refinement of the alloys down to the average grain size of 2–3 μm and 1–2 μm, respectively. In addition, in both alloys the precipitation of fine particles of phases Mg$_{54}$Ag$_{17}$ and Mg$_{5}$Gd with sizes of ~500–600 and ~400–500 nm and a volume fraction of ~9% and ~8.6%, respectively, was observed. In the case of the alloy Mg-6.0%Ag, despite a significant grain refinement, a drop in the strength characteristics and a nearly twofold increase in ductility (up to ~30%) was found. This behavior is associated with the formation of a sharp inclined basal texture. For alloy Mg-10.0%Gd, both ductility and strength were enhanced, which can be associated with the combined effect of significant grain refinement and an increased probability of prismatic and basal glide. ECAP was also shown to cause a substantial rise of the biodegradation rate of both alloys and an increase in pitting corrosion. The latter effect is attributed to an increase in the dislocation density induced by ECAP and the occurrence of micro-galvanic corrosion at the matrix/particle interfaces

Selective Constraints on Amino Acids Estimated by a Mechanistic Codon Substitution Model with Multiple Nucleotide Changes

Empirical substitution matrices represent the average tendencies of substitutions over various protein families by sacrificing gene-level resolution. We develop a codon-based model, in which mutational tendencies of codon, a genetic code, and the strength of selective constraints against amino acid replacements can be tailored to a given gene. First, selective constraints averaged over proteins are estimated by maximizing the likelihood of each 1-PAM matrix of empirical amino acid (JTT, WAG, and LG) and codon (KHG) substitution matrices. Then, selective constraints specific to given proteins are approximated as a linear function of those estimated from the empirical substitution matrices. Akaike information criterion (AIC) values indicate that a model allowing multiple nucleotide changes fits the empirical substitution matrices significantly better. Also, the ML estimates of transition-transversion bias obtained from these empirical matrices are not so large as previously estimated. The selective constraints are characteristic of proteins rather than species. However, their relative strengths among amino acid pairs can be approximated not to depend very much on protein families but amino acid pairs, because the present model, in which selective constraints are approximated to be a linear function of those estimated from the JTT/WAG/LG/KHG matrices, can provide a good fit to other empirical substitution matrices including cpREV for chloroplast proteins and mtREV for vertebrate mitochondrial proteins. The present codon-based model with the ML estimates of selective constraints and with adjustable mutation rates of nucleotide would be useful as a simple substitution model in ML and Bayesian inferences of molecular phylogenetic trees, and enables us to obtain biologically meaningful information at both nucleotide and amino acid levels from codon and protein sequences.Comment: Table 9 in this article includes corrections for errata in the Table 9 published in 10.1371/journal.pone.0017244. Supporting information is attached at the end of the article, and a computer-readable dataset of the ML estimates of selective constraints is available from 10.1371/journal.pone.001724