Switching Casimir forces with Phase Change Materials

We demonstrate here a controllable variation in the Casimir force. Changes in the force of up to 20% at separations of ~100 nm between Au and AgInSbTe (AIST) surfaces were achieved upon crystallization of an amorphous sample of AIST. This material is well known for its structural transformation, which produces a significant change in the optical properties and is exploited in optical data storage systems. The finding paves the way to the control of forces in nanosystems, such as micro- or nanoswitches by stimulating the phase change transition via localized heat sources.Comment: 7 pages, 3 figures The AFM images for the inset in Fig.2 were replaced with new ones as obtained with tips having high aspect rati

Design of the University Mobile Educational Environment

The article addresses issues related to the description of the aspects of the instructional design of a mobile educational environment of a modern higher education institution. The authors give the definitions of the mobile educational environment, describe its functional features, and also consider the requirements for its instructional design and development. The article presents the clustering of digital services for the full implementation of a mobile educational environment (services for planning and supporting educational activities, services for organizing and supporting educational activities, communication and feedback services, general information services). The results of the experimental research to identify the attitude of students, teachers and administrative workers to the functional significance of mobile technologies and their application in the educational process are presented

Endothelial dysfunction in adolescents with arterial hypertension: results of rheovasographic evaluation and heart rate variability analysis

Background As a major regulator of local vascular homeostasis, the endothelium maintains vascular tone through the balance between vasodilatation and vasoconstriction. Upsetting this tight balance leads to endothelial dysfunction . The latter is thought to be a marker of future cardiovascular events in hypertensive patients. The purpose of this research was to assess endothelial vasomotor function with relation to heart rate variability in adolescents with arterial hypertension. Material and methods 56 adolescents (33 males, 23 females, aged 22 ± 2 years) were subdivided into equal groups (regarding gender, age, body mass index and genetic burden) according to hypertension appearance and smoking habits. All of them underwent forearm rheovasography with measurements of reactive hyperemia test heart rate variability being taken (a five-minute recording). As reliable values for evaluating endothelial function, relative changes in the peak blood flow velocity (DdZ/ /dT) and pulse blood volume (DdV) at the 1st min after reperfusion were used. The following parameters of the time (RRNN, SDNN, RMSSD, pNN50, CV) and frequency (TP, VLF, LF, HF; LF/HF) domain analysis were used for assessing heart rate modulation. Results Our analysis elicited a significant difference in both velocity and volume characteristics between hypertensive smokers and healthy individuals. Endothelial function in hypertensive non-smoking patients and normotensive smokers was also impaired. Heart rate variability was decreased and sympathetic tone prevailed in hypertensive adolescents. Both are associated with endothelial dysfunction. Conclusions Endothelial function is likely to be impaired in hypertensive adolescents, particularly among those who smoke. Moreover, heart rate variability is decreased and sympathetic tone prevails with relation to endothelial dysfunction towards the autonomic imbalance

ПРОГНОЗУВАННЯ РЕЗУЛЬТАТИВНОСТІ ІННОВАЦІЙНИХ ПРОЄКТІВ

The article examines the role of innovations in the development of the national economy. We have analyzed the dynamics of budget financing of strategic priorities of innovative activities and activities in the field of technology transfer in Ukraine for 2019-2021. Priorities support increases annually, and there were identified priorities where funding  decreases.We conducted a predictive assessment of innovative projects using the clustering procedure. The implementation of the proposed proposal is highlighted in the example of 46 research works in the medical field. A scoring system for planned scientific results and products of research work has been developed, and relative values of indicators were calculated,  which were the basis of clustering. The Fuzzy Clustering and Data Analysis  Toolbox program set is used to solve the problem of fuzzy clustering based  on the fuzzy c-means algorithm. It was determined that factors such as  novelty, the expected effect of implementation, the methodological level and  material and technical base of the study, and the qualifications of the  main performers of the study have an impact on the predictive effectiveness  and the final results. The results of clustering research work according to the specified indicators, and three clusters were obtained. Analysis of the structure of indicators in clusters showed that the first cluster includes the most effective research works and the second – intermediate ones. The  hird cluster includes ineffective scientific research. Attribution of the planned research to a certain cluster based on expert evaluations of four  selected informative indicators allows for predicting the possible  ffectiveness of the innovation with sufficient accuracy.The statistic of indicators of average scores in each cluster was analyzed. Reliable differences between clusters were established using the non-parametric Mann-Whitney test. The conducted clustering provides reasonable recommendations regarding the feasibility of financing  an innovative project based on forecast expert assessments. У статті розглянуто роль інновацій у розвитку національної економіки.  Проаналізовано динаміку бюджетного фінансування стратегічних  пріоритетів інноваційної діяльності та діяльності у сфері трансферу  технологій в Україні за 2019–2021 роки. Визначено пріоритети, підтримка  яких зростає щорічно, та пріоритети, де фінансування зменшується. Запропоновано здійснювати прогнозну оцінку інноваційних проєктів з використанням процедури кластреризації.  Висвітлено реалізацію винесеної пропозиції на прикладі науково-дослідних робіт медичної сфери. Показано бальну систему експертної  оцінки інноваційних розробок. Визначено показники, що мають  найбільший вплив на прогнозну ефективність. Наведено результати кластеризації науково-дослідних робіт за визначеними показниками. Проаналізовані статистичні показники середніх бальних оцінок в  кожному кластері. Встановлено достовірні відмінності між кластерами з використанням непараметричного критерію Манна–Уітні. Проведена  кластеризація дає обґрунтовані рекомендації щодо доцільності  фінансування інноваційного проєкту на основі прогнозних експертних оцінок.

Молекулярно-генетический полиморфизм популяций американской норки (Neovison vison) в модельных звероводческих хозяйствах и на прилегающих к ним территориях в Беларуси

American mink (Neovison vison) is both a problematic invader and an economically valuable fur breed species in Belarus. The increasing scale of mink breeding for fur and the growing impact of this invasive species on the local ecosystems requires sound, novel strategies for managing both farm and wild populations. Containment of wild American mink populations under the effects of possible migration from the fur farms could be especially problematic. With that issue in mind, we have used microsatellite analysis todetermine the genetic polymorphism in two color breeds of farm-bred American mink in the populations of several Belorussian model fur farms, as well as the same characteristics for the feral populations on the territories adjacent to said fur farms. We confirm the presence of effective influx of mink into the wild from fur farms, determined through the means of analyzing microsatellite genotype data of feral and farm populations.Американская норка (Neovison vison) в Беларуси является одновременно проблематичным инвазивным и экономически значимым хозяйственным видом. Растущие масштабы хозяйственного разведения на мех и увеличивающееся воздействие этого вида на локальные экосистемы требует принятия надежной и последовательной стратегии менеджмента его диких и хозяйственных популяций. Этот подход поднимает проблематику контроля диких популяций американской норки в условиях потенциальной миграции особей в дикую среду из звероводческих хозяйств – встает вопрос наличия факта побегов особей в дикую среду в Беларуси. С целью разрешения этого вопроса мы осуществили генетический анализ двух хозяйственных популяций американской норки, а также диких групп на сопряженной со зверохозяйствами территории, использовав в качестве генетических маркеров микросателлиты, чем подтвердили наличия эффективного потока особей в дикую среду из зверохозяйств, а также привели характеристики генетического полиморфизма для рассматриваемых популяций американской норки

Variability of cardiac rate in patients suffering from arterial hypertension during pre- and postoperative period

The study of variability of cardiac rate was carried out in 80 patients suffering from arterial hypertension (AH) before and after laparoscopic cholecystectomy. The first group consists of the patients with corrected AP, the second - with uncorrected AP. It was detected that during pre-operative period the vegetative balance was characterized for the patients with corrected AP and the sympathetic activity with the inclusion of central contour regulation was less common but in the group of uncorrected AP emphasized sympathetic synergism was registered. After operation the reduction of AP being accompanied by the increase of the sympathetic influences takes place in both groups. In cases of hypotension the vegetative balance is mainly registered, moderate sppathicotony is not often marked, but vagotony doesn’t occur. Hence, the stability of hemodynemics during the lowering of AP in the post-operative patients suffering from AH is determined by the growing sympathetic activation with the strengthening of coordinative effects of the cerebral regulatory structures but moderate hypotension is mainly defined by the vegetative balance.У 80 больных с АГ до и после лапароскопической холецистэктомии проводилось исследование вариабельности сердечного ритма. Первую группу составили пациенты с корригированным АД, а вторую - с некорригированным АД. Выявлено, что в предоперационном периоде для больных с корригированным АД характерно вегетативное равновесие и реже - симпатическая активность с включением центрального контура регуляции, а при некорригированном АД - акцентированный симпатической синергизм. После операции в обеих группах происходит снижение АД, сопровождающееся усилением симпатических влияний. В случаях гипотонии преимущественно регистрируется вегетативное равновесие, редко - умеренная симпатикотония, а ваготония не встречается. Следовательно, стабильность гемодинамики при снижении АД в послеоперационном периоде у больных АГ определяется нарастающей симпатической активацией с усилением координирующих влияний церебральных структур регуляции, а умеренная гипотония — преимущественно вегетативным равновесием

Aggregate structure of hydroxyproline-rich glycoprotein (HRGP) and HRGP assisted dispersion of carbon nanotubes

Hydroxyproline-rich glycoproteins (HRGP) comprise a super-family of extracellular structural glycoproteins whose precise roles in plant cell wall assembly and functioning remain to be elucidated. However, their extended structure and repetitive block co-polymer character of HRGPs may mediate their self-assembly as wall scaffolds by like-with-like alignment of their hydrophobic peptide and hydrophilic glycopeptide modules. Intermolecular crosslinking further stabilizes the scaffold. Thus the design of HRGP-based scaffolds may have practical applications in bionanotechnology and medicine. As a first step, we have used single-molecule or single-aggregate atomic force microscopy (AFM) to visualize the structure of YK20, an amphiphilic HRGP comprised entirely of 20 tandem repeats of: Ser-Hyp4-Ser-Hyp-Ser-Hyp4-Tyr-Tyr-Tyr-Lys. YK20 formed tightly aggregated coils at low ionic strength, but networks of entangled chains with a porosity of ~0.5–3 μm at higher ionic strength. As a second step we have begun to design HRGP-carbon nanotube composites. Single-walled carbon nanotubes (SWNTs) can be considered as seamless cylinders rolled up from graphene sheets. These unique all-carbon structures have extraordinary aromatic and hydrophobic properties and form aggregated bundles due to strong inter-tube van der Waals interactions. Sonicating aggregated SWNT bundles with aqueous YK20 solubilized them presumably by interaction with the repetitive, hydrophobic, Tyr-rich peptide modules of YK20 with retention of the extended polyproline-II character. This may allow YK20 to form extended structures that could potentially be used as scaffolds for site-directed assembly of nanomaterials

Synthetic Polymers Provide a Robust Substrate for Functional Neuron Culture

Substrates for neuron culture and implantation are required to be both biocompatible and display surface compositions that support cell attachment, growth, differentiation, and neural activity. Laminin, a naturally occurring extracellular matrix protein is the most widely used substrate for neuron culture and fulfills some of these requirements, however, it is expensive, unstable (compared to synthetic materials), and prone to batch-to-batch variation. This study uses a high-throughput polymer screening approach to identify synthetic polymers that supports the in vitro culture of primary mouse cerebellar neurons. This allows the identification of materials that enable primary cell attachment with high viability even under “serum-free” conditions, with materials that support both primary cells and neural progenitor cell attachment with high levels of neuronal biomarker expression, while promoting progenitor cell maturation to neurons.Biomaterials & Tissue Biomechanic