Моделирование процессов деформирования и разрушения нанокомпозитов Al/Cu

The aim of this work is to carry out molecular dynamics simulation of the uniaxial stretching of a cooled Al/Cu composition. The LAMMPS software package has been used for calculations, which includes the classic molecular dynamics code with an emphasis on modeling materials. The Ovito program has been used for visualization, which has a large number of functions, so that the user can thoroughly investigate the results obtained. When describing the interatomic interaction in the Al/Cu nanocomposite, we used the potential of the embedded EAM atom. The choice of potential is due to the fact that it adequately describes and reproduces the properties of a wide class of materials, including metals, semiconductors and alloys. The simulation has been carried out in two stages. At the first stage, a sample consisting of two crystallites of aluminum and copper in the form of parallelepipeds, connected along one of the joint boundaries, was placed in the computational domain and cooled at constant pressure. Cooling was carried out to stabilize the nanosystem. At the second stage, corresponding to the deformation, the temperature and pressure were changed in accordance with the ongoing physical processes. The algorithm of the thermostat and the Nose – Hoover barostat has been used to control the temperature and pressure at the initial stage of cooling. The paper demonstrates the nature of the distribution of longitudinal stresses over the entire volume of the crystal in the process of stretching. When the sample reached the elastic limit, the nucleation of crystal lattice defects and their distribution over the crystal in the form of shifts and rotations of atoms in crystal planes were observed. Areas of plastic deformation origin have been determined. The maximum destruction of the material occurred along the interface. The parameters of the Al/Cu composition (deformation, temperature, mechanical stress) have been dynamically investigated using molecular dynamics simulation. Comparison of the characteristics of the sample in the deformation process has been carried. Under loading conditions, a variety of processes are implemented in the material, including generation of defects, elastic and plastic deformation, generation of damage, and mechanical mixing.Проведено молекулярно-динамическое моделирование одноосного растяжения охлажденной композиции Al/Cu. При расчетах использовали программный комплекс LAMMPS, включающий в себя классический код молекулярной динамики с акцентом на моделирование материалов. Для визуализации применяли программу Ovito, имеющую большое количество функций, благодаря чему пользователь может тщательно исследовать полученные результаты. При описании межатомного взаимодействия в нанокомпозите Al/Cu использовали потенциал погруженного атома EAM. Выбор потенциала обусловлен тем, что он адекватно описывает и воспроизводит свойства широкого класса материалов, в том числе металлов, полупроводников и сплавов. Моделирование осуществлялось в два этапа. На первом образец, состоящий из двух кристаллитов алюминия и меди в форме параллелепипедов, соединенных вдоль одной из сводных границ, размещался в расчетной области и охлаждался при постоянном давлении. Охлаждение осуществлялось для стабилизации наносистемы. На втором этапе, соответствующем деформации, температура и давление менялись в соответствии с протекающими физическими процессами. Для управления температурой и давлением на начальной стадии охлаждения использовали алгоритм термостата и баростата Нозе – Гувера. В статье продемонстрирован характер распределения продольных напряжений по всему объему кристалла в процессе растяжения. При достижении образцом предела упругости наблюдались зарождение дефектов кристаллической решетки и распространение их по кристаллу в виде сдвигов и поворотов атомов в кристаллических плоскостях. Определены области зарождения пластических деформаций. Максимальное разрушение материала происходило по границе раздела. С помощью молекулярно-динамического моделирования динамически исследованы параметры композиции Al/Cu (деформация, температура, механическое напряжение). Проведено сопоставление характеристик образца при деформации. В условиях нагружения в материале реализуется множество процессов, включающих в себя генерацию дефектов, упругую и пластическую деформации, генерацию повреждений и механическое перемешивание

The ACTN3 R577X Polymorphism across Three Groups of Elite Male European Athletes

The ACTN3 R577X polymorphism (rs1815739) is a strong candidate to influence elite athletic performance. Yet, controversy exists in the literature owing to between-studies differences in the ethnic background and sample size of the cohorts, the latter being usually low, which makes comparisons difficult. In this case:control genetic study we determined the association between elite athletic status and the ACTN3 R577X polymorphism within three cohorts of European Caucasian men, i.e. Spanish, Polish and Russian [633 cases (278 elite endurance and 355 power athletes), and 808 non-athletic controls]. The odds ratio (OR) of a power athlete harbouring the XX versus the RR genotype compared with sedentary controls was 0.54 [95% confidence interval (CI): 0.34–0.48; P = 0.006]. We also observed that the OR of an endurance athlete having the XX versus the RR genotype compared with power athletes was 1.88 (95%CI: 1.07–3.31; P = 0.028). In endurance athletes, the OR of a “world-class” competitor having the XX genotype versus the RR+RX genotype was 3.74 (95%CI: 1.08–12.94; P = 0.038) compared with those of a lower (“national”) competition level. No association (P>0.1) was noted between the ACTN3 R577X polymorphism and competition level (world-class versus national-level) in power athletes. Our data provide comprehensive support for the influence of the ACTN3 R577X polymorphism on elite athletic performance

Athlome Project Consortium: a concerted effort to discover genomic and other "omic" markers of athletic performance.

Despite numerous attempts to discover genetic variants associated with elite athletic performance, injury predisposition, and elite/world-class athletic status, there has been limited progress to date. Past reliance on candidate gene studies predominantly focusing on genotyping a limited number of single nucleotide polymorphisms or the insertion/deletion variants in small, often heterogeneous cohorts (i.e., made up of athletes of quite different sport specialties) have not generated the kind of results that could offer solid opportunities to bridge the gap between basic research in exercise sciences and deliverables in biomedicine. A retrospective view of genetic association studies with complex disease traits indicates that transition to hypothesis-free genome-wide approaches will be more fruitful. In studies of complex disease, it is well recognized that the magnitude of genetic association is often smaller than initially anticipated, and, as such, large sample sizes are required to identify the gene effects robustly. A symposium was held in Athens and on the Greek island of Santorini from 14-17 May 2015 to review the main findings in exercise genetics and genomics and to explore promising trends and possibilities. The symposium also offered a forum for the development of a position stand (the Santorini Declaration). Among the participants, many were involved in ongoing collaborative studies (e.g., ELITE, GAMES, Gene SMART, GENESIS, and POWERGENE). A consensus emerged among participants that it would be advantageous to bring together all current studies and those recently launched into one new large collaborative initiative, which was subsequently named the Athlome Project Consortium

The odds ratio of <i>ACTN3</i> R577X (rs1815739) genotypes for endurance and power athletes, according to their competition level (world-class vs. national-level).

<p>Data are odds ratio and 95% confidence intervals.</p><p>Analysis adjusted by country. Abbreviation: ref., reference group.</p

The odds ratio of <i>ACTN3</i> R577X (rs1815739) genotypes for endurance and power athletes.

<p>Data are odds ratio and 95% confidence intervals.</p><p>Analysis adjusted by country. Abbreviation: ref., reference group.</p

Correspondence diagram of athlete type with ACTN3 R577X (rs1815739) polymorphism.

<p>Correspondence diagram of athlete type with ACTN3 R577X (rs1815739) polymorphism.</p