Surface relief of magnetoactive elastomeric films in a homogeneous magnetic field: Molecular dynamics simulations

The structure of a thin magnetoactive elastomeric (MAE) film adsorbed on a solid substrate is studied by molecular dynamics simulations. Within the adopted coarse-grained approach, a MAE film consists of magnetic particles modeled as soft-core spheres, carrying point dipoles, connected by elastic springs representing a polymer matrix. MAE films containing 20, 25 and 30 vol% of randomly distributed magnetic particles are simulated. Once a magnetic field is applied, the competition between dipolar, elastic and Zeeman forces leads to the restructuring of the layer. The distribution of the magnetic particles as well as elastic strains within the MAE films are calculated for various magnetic fields applied perpendicular to the film surface. It is shown that the surface roughness increases strongly with growing magnetic field. For a given magnetic field, the roughness is larger for the softer polymeric matrix and exhibits a nonmonotonic dependence on the magnetic particle concentration. The obtained results provide a better understanding of the MAE surface structuring as well as possible guidelines for fabrication of MAE films with a tunable surface topology. © The Royal Society of Chemistry 2019.Financial support of the Russian Foundation for Basic Research is gratefully acknowledged (grant no. 16-29-05276). The authors acknowledge support from the Ministry of Education and Science of the Russian Federation, Contract 02.A03.21.0006 (Project 3.1438.2017/4.6). P. A. S. and S. S. K. are also supported by the FWF START-Projekt Y 627-N27. S. S. K. also acknowledges support from ETN-COLLDENSE (H2020-MSCA-ITN-2014, Grant No. 642774). Computer simulations were carried out at the Vienna Scientific Cluster

Longitudinal Momentum Fraction X_L for Two High P_t Protons in pp->ppX Reaction

We present an analysis of new data from Experiment E850 at BNL. We have characterized the inclusive cross section near the endpoint for pp exclusive scattering in Hydrogen and in Carbon with incident beam energy of 6 GeV. We select events with a pair of back-to-back hadrons at large transverse momentum. These cross sections are parameterized with a form $\frac{d \sigma}{d X_{L}}$ $\sim(1-X_{L})^{p}$, where ${X_{L}}$ is the ratio of the longitudinal momentum of the observed pair to the total incident beam momentum. Small value of $p$ may suggest that the number of partons participating in the reaction is large and reaction has a strong dependence on the center-of-mass energy. We also discuss nuclear effects observed in our kinematic region.Comment: 4 pages, 2 figures, to be published in Proceedings of CIPANP2000, Quebec, May 22-28, 2000, requires aipproc.sty(included

Suppression of hole-hole scattering in GaAs/AlGaAs heterostructures under uniaxial compression

Resistance, magnetoresistance and their temperature dependencies have been investigated in the 2D hole gas at a [001] p-GaAs/Al$_{0.5}$Ga$_{0.5}$As heterointerface under [110] uniaxial compression. Analysis performed in the frame of hole-hole scattering between carriers in the two spin splitted subbands of the ground heavy hole state indicates, that h-h scattering is strongly suppressed by uniaxial compression. The decay time $\tau_{01}$ of the relative momentum reveals 4.5 times increase at a uniaxial compression of 1.3 kbar.Comment: 5 pages, 3 figures. submitted to Phys.Rev.

Международный индекс цифровой экономики и общества (I-DESI): тенденции развития цифровых технологий

Purpose of research. The aim of the study is to conduct statistical research and assess the level of digitalization of the economy of the European Union and some non-EU countries. The focus is on assessing the level, dynamics and directions of information and communication technologies development in the European economy on the example of the international index of digital economy and society (I-DESI). The strongest and weakest countries were identified, and the impact of components (sub-indexes) of the I-DESI index on GDP was studied.Materials and methods. For this study, the digital economy and society index (DESI – Digital Economy and Society Index), which is a composite measure that studies the digital indicators of Europe, developed by DG CONNECT (the European Commission) to provide an evidence-based contribution to the assessment of digital development in the EU as a whole, is considered as an assessment of the level of digitalization. Based on this index, the international digital economy and society index (I-DESI) was developed in 2018, which reflects and expands the EU-28 digital economy and society index. Based on the sub-indexes of this index, a multidimensional classification of European countries was carried out. The main components method identifies the main factors that were used to identify their impact on the level of GDP in various clusters. The Statistica package is used for information processing and analysis.Results. This study examined the values of sub-indexes of the I-DESI index in five dimensions: communication, digital skills, citizens' use of the Internet, integration of business technologies, and digital public services. According to the hierarchical classification based on these sub-indexes, 2 groups of countries were identified. Using the k-means method, the features of each cluster are identified. Comparisons of cluster analysis results by sub-indexes were made based on data from 2016 and 2013. Using the main components method, five main factors were identified out of twenty indicators characterizing the I-DESI index and their influence on the level of GDP in various clusters was revealed. The analysis of twenty indicators of the I-DESI 2018 index, applied in the method of main components, by the directions of the index itself, the economy in the context of GDP and the social sphere (life of society) through the HDI (human development index) in various clusters was also carried out.Conclusion. According to the research, two groups of countries were identified by the level of digitalization. The first group in 2016 included twenty two countries with high indicators of digital development of the economy and society. All the countries of the first cluster are developed countries that have a significant share of services in their economy, as well as investments in high-tech products. The second cluster is represented by twenty three countries. This cluster is mainly represented by developing countries, which still have a large share of production in GDP. The level of GDP in the first cluster countries with a high I-DESI index was mainly influenced by factors that characterize fixed broadband and digital public services. Two groups of factors also influenced the GDP level of the second cluster countries. One group of factors combined variables that characterize new technologies in business, the other group – the use of the Internet by the population. The study of the development of the digital economy has allowed us to conclude that in general, the trend of rapid spread of modern technologies is developing around the world. This suggests that society in the context of the state and the individual needs to be mobile and ready to adopt new technologies in advance.Цель исследования. Целью исследования является статистическое исследование и оценка уровня цифровицации экономики Евросоюза и некоторых стран не входящих ЕС. Акцент сделан на оценку уровня, динамики и направлений освоения информационно-коммуникационных технологий в экономике европейских стран на примере международного индекса цифровой экономики и общества I-DESI. Выделены наиболее сильные и слабые страны, проведено исследование влияние составляющих (субиндексов) индекса I-DESI на ВВП.Материалы и методы. Для проведения данного исследования в качестве оценке уровня цифровизации рассмотрен индекс цифровой экономики и общества (DESI – Digital Economy and Society Index), являющийся составной мерой, которая изучает цифровые показатели Европы, разработанный DG CONNECT (Европейской комиссией) для обеспечения научно обоснованного вклада в оценку цифрового развития в ЕС в целом. На основе данного индекса в 2018 году был разработан Международный индекс цифровой экономики и общества (I-DESI), который отражает и расширяет Индекс цифровой экономики и общества ЕС-28. На основе субиндексов данного индекса была проведена многомерная классификация стран Европы. Методом главных компонент выделены основные факторы, которые были использованы для выявления их влияния на уровень ВВП в различных кластерах. Для обработки информации и проведения анализа использован ППП Statistica.Результаты. В рамках данного исследования были рассмотрены значения субиндексов индекса I-DESI по пяти измерениям: связь, цифровые навыки, использование гражданами Интернета, интеграция бизнес-технологий, цифровые государственные услуги. Согласно иерархической классификации на основе данных субиндексов было выделено 2 группы стран. С помощью метода k-средних выявлены особенности каждого кластера. Сравнения результатов кластерного анализа по субиндексам были проведены по данным 2016 г. и 2013 г. Методом главных компонент из двадцати показателей, характеризующих индекс I-DESI, были выделены пять основных факторов и выявлено их влияние на уровень ВВП в различных кластерах. Также проведен анализ 20 индикаторов индекса I-DESI 2018, примененных в методе главных компонент, по направлениям самого индекса, экономики в разрезе ВВП и социальной сферы (жизни общества) через ИРЧП (индекс развития человеческого потенциала) в различных кластерах.Заключение. По данным проведенного исследования были выявлены две группы стран по уровню цифровизации. В первую группу в 2016 году вошло 22 страны с высокими показателями цифрового развития экономики и общества. Все страны первого кластера – развитые страны, имеющие в своей экономике весомую долю услуг, а также инвестиций в высокотехнологичные продукты. Второй кластер представлен 23 странами. Данный кластер в основном представлен развивающимися странами, имеющими в ВВП по-прежнему большую долю производства. На уровень ВВП в странах первого кластера, с высоким индексом I-DESI, основное влияние оказывали факторы, характеризующие фиксированную широкополосную связь и цифровые государственные услуги. На уровень ВВП стран второго кластера оказывали влияние также две группы факторов. Одна группа факторов объединила переменные, характеризующие новые технологии в бизнесе, другая группа – использование Интернета населением. Изучение особенностей развития цифровой экономики, позволило сделать вывод, что в целом по всему миру развивается тенденция быстрого распространения современных технологий. Это говорит о том, что обществу в разрезе государства и отдельной личности необходимо быть мобильными и готовыми к принятию новых технологий заранее

Suspensions of magnetic nanogels at zero field: Equilibrium structural properties

Magnetic nanogels represent a cutting edge of magnetic soft matter research due to their numerous potential applications. Here, using Langevin dynamics simulations, we analyse the influence of magnetic nanogel concentration and embedded magnetic particle interactions on the self-assembly of magnetic nanogels at zero field. For this, we calculated radial distribution functions and structure factors for nanogels and magnetic particles within them. We found that, in comparison to suspensions of free magnetic nanoparticles, where the self-assembly is already observed if the interparticle interaction strength exceeds the thermal fluctuations by approximately a factor of three, self-assembly of magnetic nanogels only takes place by increasing such ratio above six. This magnetic nanogel self-assembly is realised by means of favourable close contacts between magnetic nanoparticles from different nanogels. It turns out that for high values of interparticle interactions, corresponding to the formation of internal rings in isolated nanogels, in their suspensions larger magnetic particle clusters with lower elastic penalty can be formed by involving different nanogels. Finally, we show that when the self-assembly of these nanogels takes place, it has a drastic effect on the structural properties even if the volume fraction of magnetic nanoparticles is low. © 2019 Elsevier B.V.This research has been supported by the Russian Science Foundation Grant No. 19-12-00209 . Authors acknowledge support from the Austrian Research Fund (FWF), START-Projekt Y 627-N27. Computer simulations were performed at the Vienna Scientific Cluster (VSC-3)