Типовая учебная программа по учебной дисциплине для специальности 1-23 01 07 Информация и коммуникация

ZnS nanoparticles stabilized by cetyltrimethylammonium bromide (CTAB) were modelled in the Materials Studio environment. Four types of models with different distances between ZnS nanoparticles and different amounts of CTA cations without water and in water environment were built and characterized by calculated sublimation energies. The results of molecular modelling without water showed that the most favourable model consisted of two ZnS nanoparticles with a distance of 8-9 nm separated without immersing of CTAs. On the contrary, the most favourable model in water environment was composed of ZnS nanoparticles that nearly touched each other. CTA cations exhibited tendency to be located on the ZnS surface forming sparse covers. Size distributions of ZnS-CTA particles obtained by TEM measurements well agreed with molecular modelling results.Web of Science79121559154

Habitat preferences and functional traits drive longevity in Himalayan high-mountain plants

Plant lifespan has important evolutionary, physiological, and ecological implications related to population persistence, community stability, and resilience to ongoing environmental change impacts. Although biologists have long been puzzled over the extraordinary variation in plant lifespan and its causes, our understanding of interspecific variability in plant lifespan and the key internal and external factors influencing longevity remains limited. Here, we demonstrate the concurrent impacts of environmental, morphological, physiological, and anatomical constraints on interspecific variation in longevity among > 300 vascular dicot plant species naturally occurring at an elevation gradient (2800–6150 m) in the western Himalayas. First, we show that plant longevity (ranging from 1 to 100 years) is largely related to species' habitat preferences. Ecologically stressful habitats such as alpine and subnival host long-lived species, while productive ruderal and wetland habitats contain a higher proportion of shorter-lived species. Second, longevity is influenced by growth form with monocarpic forbs having the shortest lifespan and woody shrubs having the highest. Small-statured cushion plants with compact canopies and deep roots, most found on cold and infertile alpine and subnival soils, had a higher chance of achieving longevity. Third, plant traits reflecting plant adaptations to stress and disturbance affect interspecific differences in plant longevity. We show that longevity and growth are negatively correlated. Slow-growing species are those that have a higher chance of reaching a high age. Finally, higher longevity was associated with high leaf carbon and phosphorus, low root phosphorus and nitrogen, and with large bark-xylem ratio. Our findings suggest that plant longevity in high elevation is intricately determined by a combination of habitat preferences and growth form, as well as the plant growth rate and physiological processes.publishedVersio

Cushions of Thylacospermum caespitosum (Caryophyllaceae) do not facilitate other plants under extreme altitude and dry conditions in the north-west Himalayas

† Background Cushion plants are commonly considered as keystone nurse species that ameliorate the harsh conditions they inhabit in alpine ecosystems, thus facilitating other species and increasing alpine plant biodiversity. A literature search resulted in 25 key studies showing overwhelming facilitative effects of different cushion plants and hypothesizing greater facilitation with increased environmental severity (i.e. higher altitude and/or lower rainfall). At the same time, emerging ecological theory alongside the cushion-specific literature suggests that facilitation might not always occur under extreme environmental conditions, and especially under high altitude and dryness. † Methods To assess these hypotheses, possible nursing effects of Thylacospermum caespitosum (Caryophyllaceae) were examined at extremely high altitude (5900 m a.s.l.) and in dry conditions ( precipitation ,100 mm year 21 ) in Eastern Ladakh, Trans-Himalaya. This is, by far, the highest site, and the second driest, at which the effects of cushions have been studied so far. † Key Results In accordance with the theoretical predictions, no nursing effects of T. caespitosum on other alpine plants were detected. The number and abundance of species were greater outside cushions than within and on the edge of cushions. None of the 13 species detected was positively associated with cushions, while nine of them were negatively associated. Plant diversity increased with the size of the area sampled outside cushions, but no species -area relationship was found within cushions. † Conclusions The results support the emerging theoretical prediction of restricted facilitative effects under extreme combinations of cold and dryness, integrating these ideas in the context of the ecology of cushion plants. This evidence suggests that cases of missing strong facilitation are likely to be found in other extreme alpine conditions

Ecology of alpine plants in NW Himalaya.

The westernmost spur of the Tibetan Plateau stretches to Eastern Ladakh in India. It is a region which remains poorly explored because of challenging conditions and long periods of political instability. At the same time, it is one of the highest places on earth supporting angiosperm life, which goes beyond 6000 m a.s.l. here. The whole region, due its remoteness, is practically unaffected by plant invasions and direct human activities. Thus, Ladakh represents a kind of "natural experiment", providing very long gradient of elevation suitable for comparative functional ecology as well as for testing various hypotheses concerning limitations of vascular plants. Arid climate and extreme elevations are the common factors. Our team pursued the goal of systematic botanical and ecological exploration of Ladakh, started by late Leoš Klimeš. This thesis provides insight into the main vegetation types, clonality in plants, plant-plant interactions and soil phototroph communities

Software designed 64-QAM demodulator of OFDM signal implemented into FPGA elements

This paper deals with the implementation of OFDM demodulator Digital Radio Mondiale system DRM. The article is aimed to design a 64-QAM demodulator using the software tools ”System Generator for DSP” from Xilinx and MATLAB-Simulink [1]. The theoretical performance has been verified by simulations. Moreover, demodulator’s circuit was subsequently implemented by the programmable elements into Field-Programmable Gate Arrays (FPGAs). Finally some testing measurements were made to prove the practical function in the real conditions.Scopu

Precipitation, stabilization and molecular modeling of ZnS nanoparticles in the presence of cetyltrimethylammonium bromide

ZnS nanoparticles were precipitated in aqueous dispersions of cationic surfactant cetyltrimethylammonium bromide (CTAB). The sphere radii of ZnS nanoparticles calculated by using band-gap energies steeply decreased from 4.5 nm to 2.2 nm within CTAB concentrations of 0.4–1.5 mmol L−1. Above the concentration of 1.5 mmol L−1, the radii were stabilized at R = 2.0 nm and increased up to R = 2.5 nm after 24 h. The hydrodynamic diameters of CTAB–ZnS structures observed by the dynamic light scattering (DLS) method ranged from 130 nm to 23 nm depending on CTAB concentrations of 0.5–1.5 mmol L−1. The complex structures were observed by transmission electron microscopy (TEM). At the higher CTAB concentrations, ZnS nanoparticles were surrounded by CTA+ bilayers forming positively charged micelles with the diameter of 10 nm. The positive zeta-potentials of the micelles and their agglomerates were from 16 mV to 33 mV. Wurtzite and sphalerite nanoparticles with R = 2.0 nm and 2.5 nm covered by CTA+ were modeled with and without water. Calculated sublimation energies confirmed that a bilayer arrangement of CTA+ on the ZnS nanoparticles was preferred to a monolayer.Web of Science3771635

A signal strength fluctuation prediction model based on the random forest algorithm

This article describes the effect of the weather on radio wave propagation in a mobile telecommunication network. The research is focused on urban and countryside environments where a correlation between the received signal power level and weather conditions is found using the Random Forest algorithm as a signal level approximator. The results achieved in this paper clearly indicate that it is possible to predict the behaviour of the received power level in relationship to atmospheric phenomena.Web of Science20512612

The effects of nature-inspired synthesis on silver nanoparticle generation

A wide range of methods can be used for nature-inspired metallic nanoparticle (NP) synthesis. These syntheses, however, are ongoing in the presence of diverse mixtures of different chemical compounds, and all or only a few of these contribute to resultant particle properties. Herein, the linden (Tilia sp.) inflorescence leachate and pure citric and protocatechuic acids were chosen for Ag-AgCl nanoparticle (NP) synthesis, and the resultant particles were then compared. We focused on the following four issues: (1) preparation of Ag-AgCl NPs using the Tilia sp.-based phytosynthetic protocol, (2) analytical determination of the common phenolic, nonphenolic, and inorganic profiles of three Tilia sp. types from different harvesting locations, (3) preparation of Ag-AgCl NPs using a mixture of citric and protocatechuic acids based on chromatographic evaluation, and (4) comparison of Tilia-based and organic acid-based syntheses. Our research confirms that the Tilia organic and inorganic profiles in biomasses are influenced by the harvesting location, and the three sites influenced both the morphology and final NP size. Our processing method was uniform, and this enabled great Ag-AgCl NP reproducibility for each specific biomass. We were then able to prove that the simplified organic acid-based synthesis produced even smaller NPs than Tilia-based synthesis. These findings provide better understanding of the significant influence on NP final properties resulting from other organic acids contained in the linden.Web of Science7

Data from: Sink limitation of plant growth determines treeline in the arid Himalayas

1. Understanding what determines the high elevation limits of trees is crucial for predicting how treelines may shift in response to climate change. Treeline formation is commonly explained by a low-temperature restriction of meristematic activity (sink limitation) rather than carbon assimilation (source limitation). In arid mountains, however, trees face simultaneously low temperature and drought, both potentially restricting their growth and thus setting range limits. However, the mechanisms of treeline formation in high arid mountains are largely unknown. 2. We studied Myricaria elegans, one of the world’s highest growing winter-deciduous woody species, endemic to the arid Himalayas. We hypothesized that the upper elevation limit of Myricaria is associated with low-temperatures during the early growing season affecting earlywood formation, while later in the season drought is constraining earlywood maturation and latewood formation. 3. To test this hypothesis, we studied the quantitative anatomy of tree rings at different developmental stages across the entire species elevation range (3200-4400 m). We also explored daily stem increment and rehydration rates, seasonal dynamics of non-structural carbohydrates and stable C isotopes as a proxy for possible drought constraints. 4. Both earlywood and latewood increments decreased towards the treeline, while NSC in leaves, twigs and stem sapwood did not change, indicating a sink limitation as a main driver of the treeline. At treeline, low temperatures restricted earlywood formation more than latewood formation. Treeline individuals had – compared to individuals from lower elevations – smaller and fewer earlywood vessels, frequent frost rings and shorter periods with positive daily increments, but comparable night-time stem rehydration rates and latewood density. All these results suggest a sink limitation as a main mechanism behind the treeline formation in high arid mountains. 5. In the arid Himalayas, the treeline is set by the drastic growth reduction (sink limitation) caused by low temperature and short growing season under otherwise sufficient carbon and water supply. Spring freezing and high summer temperatures further constrain stem increment at treeline. The mean 6.9 °C temperature during the growing season places the Myricaria treeline within the thermal range of other high elevation treelines worldwide and support a common mechanism of alpine treeline formation