Identification of Populus nigra, P. laurifolia and P. × jrtyschensis by leaf petiole anatomy

Remarkable variability in morphology of the Populus genus, as well as widely spread hybridization within the genus complicate taxa identification. Petiole anatomy plays an important role in plant taxonomic attribution and resolution of arguments in systematics. The aim of the study was to examine the petiole anatomy of P. nigra, P. laurifolia and P. × jrtyschensis to assess its potential use for taxa identification. The leaf petioles were collected from 252 individual trees in 8 populations of P. nigra, P. laurifolia and P.× jrtyschensis in the area of their natural hybridization in the basin of the Tom River in Kemerovo Oblast. Two of those 8 populations, located far from the hybridization centers, were regarded as controls to characterize parent taxa. Cross sections were made in the upper part of petioles. Then the sections were used to examine the shape of petiole cross sections, the contour of the adaxial sides, the vascular system types and lower ring shape. The petioles of trees growing far from hybridization areas were found to differ in their vascular systems: P. nigra had a linear, while P. laurifolia a high­arc­shaped one. The hybrids were found to belong to several types of vascular systems, namely intermediate, high­intermediate, linear and high­arc­shaped ones. The intermediate type of vascular system is characteristic of the most part of P. × jrtyschensis trees (78 % of the total samplings). Therefore most of them can be classified as F1 hybrid and others – as a recombinant species. Examination of P. nigra in its natural hybridization center allowed finding an approach to the identification back­crosses. The study confirmed provides a solid basis for the identification of parent species, hybrids and backcrosses in natural hybridization areas of taxa belonging to Aigeiros and Tacamahaca sections of Populus genus

PHENETIC ANALYSIS OF POPULUS NIGRA, P. LAURIFOLIA AND P. × JRTYSCHENSIS IN NATURAL HYBRIDIZATION ZONE

The wide spread of hybridization in the genus Populus, including spontaneous hybridization, caused by cultivars, requires studying the variability and inheritance of morphological traits by hybrids for initial tracking of these processes. The analysis of endogenous, intra- and inter-population variability was performed on 533 individual poplar trees in seven populations of P. nigra, seven populations of P. laurifolia and four populations of P. × jrtyschensis in the Tom river basin. On each specimen, 15 leaves from short mid-crown branches were collected to determine the shape of the leaf blade, the shape of its tip and base, as well as the branch morphotype. Some biometric indicators were proposed for geometric assessment of the leaf blade shapes of poplar species. The analysis showed that of all the traits examined only the leaf blade shape did not meet the criterion for “phene”, since it is usually represented by several forms in the crown of one and the same tree. In all the species studied, the level of their intra-population diversity was found to be much higher than the inter-population one. According to the increase of intra-population variability of qualitative traits, the taxa could be ranked as P. nigra < P. laurifolia < P. × jrtyschensis. The share of inter-population diversity differed among the species studied, accounting for 21.5% in P. laurifolia, 13.8% in P. nigra and 8.0% in P. × jrtyschensis. The P. laurifolia populations showed the greatest inter-population differentiation, most likely because of a disjunct distribution due to narrow specialization to the montane river environment. The lower differentiation in P. nigra is probably due to the facts that this species dominates the poplar stands of the Tom River basin; its populations are not fragmented and are linked by vast gene flow. In P. nigra, an increase in the diversity of qualitative characteristics and phenotypes was observed in populations confined to hybridization centers. Natural selection is most likely the factor governing the inter-population differentiation in P. × jrtyschensis, leading to the predominance of F1 hybrids in populations and hence to a sharp decrease in inter-population variability

Magnetic and magnetocaloric properties of (MnCo)1-xGe compounds

The crystal structure, magnetic properties, and heat capacity of the (MnCo)1-xGe compounds with x ≤ 0.05 have been studied. It was found that, as the deviation from the MnCoGe stoichiometric composition increases, the temperature of structural transition from the low-temperature phase with the orthorhombic TiNiSi-type structure to the high-temperature phase with the hexagonal Ni2In-type phase decreases rapidly, whereas the magnetic ordering temperature varies slightly. The temperature of structural transition for the composition with x = 0.02 approximately coincides with the Curie temperature of the hexagonal phase, and the transition is accompanied by a significant entropy change, namely, ΔS = 34 J/(kg K). The application of high magnetic field in the transition-temperature range causes an increase in the relative volume of the orthorhombic phase. An analysis of magnetocaloric properties of these compounds, which was performed with the formal application of the Maxwell's relationship near the temperature of first-order structural phase transition, is shown to give overestimated values of the entropy change. © Pleiades Publishing, Ltd., 2013

The use of digital technologies in education: the case of physics learning

The article reveals the trends in the use of digital technologies in teaching physics by summarizing scientific results over the past 20 years. To solve the problem, a bibliographic analysis of the sources of the scientometric database of the WOS was used with the involvement of the computer tool VOSviewer (for the construction and visualization of bibliographic data) as of June 2023. The tool was used to analyse publications by keywords (a network of connections is built on the basis of all keywords of given publications). Networks of connections of keywords were built according to the queries: “physics learning”, “physics education”, “physics teaching” and “technologies”, as well as “digital technologies in teaching physics”, “physics application”, “mobile physics learning”, “virtual physics laboratory”, “digital physics laboratory”, “virtual reality & physics”, “augmented reality & physics”. The situation of the use of digital technologies in teaching physics is characterized by four aspects (general, technological, educational motivational, and educational-organizational). Modern trends in teaching physics are singled out: the use of environments where simulation, modelling, visualization, virtualization of physical processes, etc. are possible. The increasing popularity of virtual, augmented, and mixed reality tools; use of mobile applications for learning physics; using artificial intelligence to teach physics; organization of an educational environment based on mobile or online learning, where active learning methods are determined to be appropriate. The importance of developing young people’s intellectual skills (computational skills, algorithmic thinking skills, modelling processes, etc.) and visual thinking for the successful mastery of various sections of physics has been confirmed. The demand for integration links between natural sciences, mathematics, engineering, and digital technologies for STEM education has been monitored. Recommendations for the training of physics teachers have been formulated

Ancient origin, functional conservation and fast evolution of DNA-dependent RNA polymerase III

RNA polymerase III contains seventeen subunits in yeasts (Saccharomyces cerevisiae and Schizosaccharomyces pombe) and in human cells. Twelve of them are akin to the core RNA polymerase I or II. The five other are RNA polymerase III-specific and form the functionally distinct groups Rpc31-Rpc34-Rpc82 and Rpc37-Rpc53. Currently sequenced eukaryotic genomes revealed significant homology to these seventeen subunits in Fungi, Animals, Plants and Amoebozoans. Except for subunit Rpc31, this also extended to the much more distantly related genomes of Alveolates and Excavates, indicating that the complex subunit organization of RNA polymerase III emerged at a very early stage of eukaryotic evolution. The Sch.pombe subunits were expressed in S.cerevisiae null mutants and tested for growth. Ten core subunits showed heterospecific complementation, but the two largest catalytic subunits (Rpc1 and Rpc2) and all five RNA polymerase III-specific subunits (Rpc82, Rpc53, Rpc37, Rpc34 and Rpc31) were non-functional. Three highly conserved RNA polymerase III-specific domains were found in the twelve-subunit core structure. They correspond to the Rpc17-Rpc25 dimer, involved in transcription initiation, to an N-terminal domain of the largest subunit Rpc1 important to anchor Rpc31, Rpc34 and Rpc82, and to a C-terminal domain of Rpc1 that presumably holds Rpc37, Rpc53 and their Rpc11 partner

СЕМЕННАЯ ПРОДУКТИВНОСТЬ И РАЗВИТИЕ СЕЯНЦЕВ POPULUS × JRTYSCHENSIS CH. Y. YANG

The research explores the seed productivity and plantlets growth in the free pollination of the natural hybrid taxon P. × jrtyschensis. Fruits of P. × jrtyschensis were selected from four plants that grow in the collection ofResearchCenter“EducationalBotanical Garden” ofKemerovoStateUniversity. Four P. nigra model trees, randomly selected from theTomRiverfloodplain population, were applied as a control group. The authors used 30 fruit-bearing amentumsfrom each model. The researchers measured set of fruit (capsule); number of ovules per fruit; number of seeds per fruit; set of seeds.. Laboratory germination was determined by sowing Petri dishes on wet filter paper. The authors found out sowing germination by sowing 100 seeds in a box with soil and drainage. The energy of germination was determined on the second day while germination - on the fifth day. P. × jrtyschensis is characterized by a lower level of seed productivity (15-30%) compared to P. nigra. In terms of laboratory germination of seeds, the descendants of hybrids surpassed many P. nigra models, but their soil germination was 20-30% lower than that of black poplar. The observed variability in reproductive indices of both P. × jrtyschensis and P. nigra is mainly caused by specific features of their genotypes. Plantlets being developed, the authors observed no significant differences among the descendants of P. nigra and hybrids. The researchers highlighted plantlets that can stop growing and even more abnormal plants with one, three or four seeds in P. × jrtyschensis. This may be caused by underdevelopment of hypocotyl or germ root. The authors observed breaches in development of P. nigra just once. They outline high plantlets destruction when sowing hybrids on the first day after germination The share of destructed plants within a month (from the beginning of the experiment) reaches 66,0 %, and in P. nigra it does not exceed 40,0 %.Исследования проводились с целью изучения семенной продуктивности и роста сеянцев при свободном опылении естественного гибридного таксона P. × jrtyschensis. Плоды P. × jrtyschensis были отобраны с четырех растений, произрастающих в коллекции НОЦ «Учебный ботанический сад» НФИ КемГУ. В качестве контроля использовались четыре модельных дерева P. nigra, рандомизированно отобранных в популяции поймы р. Томи. На каждой модели отбиралось по 30 плодущих сережек. Измерению подвергнуты: завязываемость плодов (коробочек); количество семязачатков на плод; количество семян на плод; завязываемость семян. Лабораторную всхожесть определяли, проводя посев в чашки Петри на влажную фильтровальную бумагу. Посевную всхожесть устанавливали посевом 100 семян в ящик с почвой и дренажом. Энергию прорастания определяли на вторые сутки, всхожесть – на пятые. Для P. × jrtyschensis характерен более низкий уровень семенной продуктивности на (15–30%) по сравнению с P. nigra. По показателю лабораторной всхожести семян потомки гибридов превзошли большинство моделей P. nigra, но их грунтовая всхожесть оказалась на 20–30% ниже, чем у осокоря. Наблюдаемая изменчивость репродуктивных показателей как особей P. × jrtyschensis, так и P. nigra, на наш взгляд, в значительной мере обусловлена спецификой их генотипов. В процессе развития проростков существенных отличий между потомками P. nigra и гибридов не наблюдалось. У P. × jrtyschensis часто встречаются сеянцы, прекращающие рост в силу недоразвития гипокотиля или зародышевого корешка, а также больше аномальных растений с одной, тремя или четырьмя семядолями. У P. nigra нарушения развития наблюдались в потомстве только одной особи. При посеве семян гибридов в грунт уже в первые сутки после прорастания наблюдается высокая гибель сеянцев. Доля погибших растений через месяц от начала эксперимента достигает 66,0%, а у P. nigra не превышает 40,0%

Developing models of IoT infrastructures to identify vulnerabilities and analyse threats

This article describes the developing stands of typical IoT infrastructure Technologies, which are designed to identify vulnerabilities and analyse potential threats. Scenarios of attacks typical for such systems have been developed, and the consequences of implementing attacks have been determined. Attacker can use the developed scenarios, been motivated by different goal