Влияние слоистых нанонаполнителей на перколяционные свойства систем на основе полипропиленгликоля и карбонанотрубок

Використовуючи методи імпедансної спектроскопії та оптичної мікроскопії, проведено дослідження електричних властивостей систем на основі поліпропіленгліколю і карбонанотрубок (КНТ). Показано, що при введенні в систему шаруватого наповнювача, який ексфоліює, відбувається зміщення порога перколяції в область нижчих концентрацій КНТ. Аналіз критичних індексів провідності для досліджуваних систем виявив, що такі низькі значення t (1,19—1,43) свідчать про те, що формування провідної сітки, завдяки сильному притяганню між індивідуальними КНТ та лапонітом, не є статистичним перколяційним процесом, який передбачає рівномірне розподілення частинок нанонаповнювача. Таким чином, введення третього компонента за рахунок його взаємодії з нанорозмірними електропровідними частинками веде до істотної зміни перколяційних властивостей наповненої системи, що значною мірою відображається на електричній провідності композитів.By using impedance spectroscopy and optical microscopy methods the investigation of electrical properties of systems based on polypropylene glycol was conducted. It was shown that adding exfoliated layered fillers to the system shifts percolation threshold to low concentration of nanotubes. Analysis of critical indexes of conductivity for investigated systems has shown that such low values of t (1,19—1,43) mean that the formation of conductive network because of strong interaction between laponite and single nanotubes is not a statistic percolation process and distribution of filler particles is nonuniform. Thus, incorporation of third component leads to significant change of percolation properties of filled system, because of its strong interaction with conductive particles. Moreover, insertion of third component leads to significant enhancement of distribution of nanotubes in the bulk of polymer matrix and can improve a number of properties of system filled with nanosized particles polymers.Используя метод импедансной спектроскопии и оптической микроскопии, были проведены исследования электрических свойств систем на основе полипропиленгликоля и карбонанотрубок (КНТ). Показано, что при введении в систему слоистого наполнителя, который эксфолиирует, происходит смещение порога перколяции в область более низких концентраций КНТ. Анализ критических индексов проводимости для исследуемых систем показал, что такие низкие значения t (1,19—1,43) свидетельствуют о том, что формирование электропроводной сетки, вследствие сильного притягивания между индивидуальными КНТ и лапонитом, не является статистическим перколяционным процессом, который предусматривает равномерное распределение наполнителя. Таким образом, введение третьего компонента за счет его взаимодействия с наноразмерными электропроводящими частичками приводит к существенному изменению перколяционных свойств наполненной системы, что в значительной степени отображается на электрической проводимости композитов

Metallurgical hydrogen as an indicator and cause of damage of rolled steel

Fatigue tests and measurements of the volumetric distribution of metallurgical hydrogen in specimens cut from rolled I-beam 60Sh3 made of steel 10KhSND were carried out. Fatigue tests show a 20% reduction in fatigue limits compared to similar sheet material. On the fractures of the samples, there are flock-like defects in the areas of interface of the flanges of the I-beam or in the so-called zones of difficult deformation. The concentration of metallurgical hydrogen is unevenly distributed and varies from 0.17 ppm to 1.8 ppm. Large concentrations of hydrogen are observed in the zones of difficult deformation, which indicates the hydrogen nature of the metal defects observed at the fracture. The result of mechanical tests and hydrogen diagnostics is a manufacturing defect of rolled products that cannot be corrected. Hydrogen diagnostics using metallurgical hydrogen (without hydrogen charging samples) requires essentially less time than mechanical tests and yields the adequate result

Dynamics of the bioclimatic potential of agroecological zones of the Altai Territory in the conditions of modern climatic and anthropogenic changes

The steppe zone is characterized by high dynamism of environmental conditions including sharp climatic fluctuations that affect both the possibilities of agriculture and the state of steppe landscapes. Further development of agriculture without taking into account changing climatic and environmental factors increases risks both for steppe ecosystems and for the sustainability of agriculture. The field production of the agro-climatic zones of the Altai Territory is characterized by the high variability of gross yields associated with the dynamics of precipitation, air temperature, and soil fertility. Under the current conditions, the analysis of the temporal and spatial dynamics of bioclimatic potential is of high practical importance for the development and implementation of adaptive agricultural technologies. A retrospective analysis was carried out and a modern bio-climatic characteristic of model territories representing various agroecological zones was compiled for this purpose. The object of research was data on average daily, average monthly, and average annual air temperatures, the level of precipitation, the water vapor pressure, and relative humidity. Statistical processing of analytical data was carried out in Excel. Calculations revealed significant temporal and spatial dynamics of the BCP. Spatially, it is characterized by a significant decrease in a north-western orientation. The lowest average values, 1.71-1.81 units, were observed in the Kulunda and Rubtsovskaya agroecological zones, with a coefficient of variation of more than 20.0%. The Zarinskaya and Aleyskaya agroecological zones were characterized by the highest values of BCP, and the Predgornaya zone presented maximum values of BCP, at the level of 2.70 units with high stability. Temporally, the BCP of the Zarinskaya, Kulunda, and Priobskaya agroclimatic zones is characterized by a negative trend; in other zones, its almost zero balance is noted. A sufficiently expressed difference in the BCP of various agroecological zones has an impact on the realization of the biological potential of cultivated crops. Analysis of the level of development of the vegetative mass of spring wheat by determining NDVI confirmed this assumption. For a systematic assessment of the influence of climatic and anthropogenic factors on the production process of field crops and the development of measures for the rational use of agricultural landscapes, it is advisable to determine the potential yield according to the BCP, determine the degree of its implementation in the economic harvest and justify techniques for leveling limiting factors in agrotechnology of individual agroecological zones

Crowdsourcing Fungal Biodiversity : Revision of Inaturalist Observations in Northwestern Siberia

The paper presents the first analysis of crowdsourcing data of all observations of fungi (including lichens) and myxomycetes in Northwestern Siberia uploaded to iNaturalist.org to date (24.02.2022). The Introduction presents an analysis of fungal diversity crowdsourcing globally, in Russia, and in the region of interest. Materials and methods describe the protocol of uploading data to iNaturalist.org, the structure of the crowdsourcing community. initiative to revise the accumulated data. procedures of data analysis, and compilation of a dataset of revised crowdsourced data. The Results present the analysis of accumulated data by several parameters: temporal, geographical and taxonomical scope, observation and identification efforts, identifiability of various taxa, species novelty and Red Data Book categories and the protection status of registered observations. The Discussion provides data on usability of crowdsourcing data for biodiversity research and conservation of fungi, including pros and contras. The Electronic Supplements to the paper include an annotated checklist of observations of protected species with information on Red Data Book categories and the protection status, and an annotated checklist of regional records of new taxa. The paper is supplemented with a dataset of about 15 000 revised and annotated records available through Global Biodiversity Information Facility (GBIF). The tradition of crowdsourcing is rooted in mycological societies around the world, including Russia. In Northwestern Siberia, a regional mycological club was established in 2018, encouraging its members to contribute observations of fungi on iNaturalist.org. A total of about 15 000 observations of fungi and myxomycetes were uploaded so far, by about 200 observers, from three administrative regions (Yamalo-Nenetsky Autonomous Okrug, Khanty-Mansi Autonomous Okrug, and Tyumen Region). The geographical coverage of crowdsourcing observations remains low. However. the observation activity has increased in the last four years. The goal of this study consisted of a collaborative effort of professional mycologists invited to help with the identification of these observations and analysis of the accumulated data. As a result, all observations were reviewed by at least one expert. About half of all the observations have been identified reliably to the species level and received Research Grade status. Of those, 90 species (195 records) represented records of taxa new to their respective regions: 876 records of 53 species of protected species provide important data for conservation programmes. The other half of the observations consists of records still under-identified for various reasons: poor quality photographs, complex taxa (impossible to identify without microscopic or molecular study). or lack of experts in a particular taxonomic group. The Discussion section summarises the pros and cons of the use of crowdsourcing for the study and conservation of regional fungal diversity, and summarises the dispute on this subject among mycologists. Further research initiatives involving crowdsourcing data must focus on an increase in the quality of observations and strive to introduce the habit of collecting voucher specimens among the community of amateurs. The timely feedback from experts is also important to provide quality and the increase of personal involvement.Peer reviewe

Phenological shifts of abiotic events, producers and consumers across a continent

Ongoing climate change can shift organism phenology in ways that vary depending on species, habitats and climate factors studied. To probe for large-scale patterns in associated phenological change, we use 70,709 observations from six decades of systematic monitoring across the former Union of Soviet Socialist Republics. Among 110 phenological events related to plants, birds, insects, amphibians and fungi, we find a mosaic of change, defying simple predictions of earlier springs, later autumns and stronger changes at higher latitudes and elevations. Site mean temperature emerged as a strong predictor of local phenology, but the magnitude and direction of change varied with trophic level and the relative timing of an event. Beyond temperature-associated variation, we uncover high variation among both sites and years, with some sites being characterized by disproportionately long seasons and others by short ones. Our findings emphasize concerns regarding ecosystem integrity and highlight the difficulty of predicting climate change outcomes. The authors use systematic monitoring across the former USSR to investigate phenological changes across taxa. The long-term mean temperature of a site emerged as a strong predictor of phenological change, with further imprints of trophic level, event timing, site, year and biotic interactions.Peer reviewe

Chronicles of nature calendar, a long-term and large-scale multitaxon database on phenology

We present an extensive, large-scale, long-term and multitaxon database on phenological and climatic variation, involving 506,186 observation dates acquired in 471 localities in Russian Federation, Ukraine, Uzbekistan, Belarus and Kyrgyzstan. The data cover the period 1890-2018, with 96% of the data being from 1960 onwards. The database is rich in plants, birds and climatic events, but also includes insects, amphibians, reptiles and fungi. The database includes multiple events per species, such as the onset days of leaf unfolding and leaf fall for plants, and the days for first spring and last autumn occurrences for birds. The data were acquired using standardized methods by permanent staff of national parks and nature reserves (87% of the data) and members of a phenological observation network (13% of the data). The database is valuable for exploring how species respond in their phenology to climate change. Large-scale analyses of spatial variation in phenological response can help to better predict the consequences of species and community responses to climate change.Peer reviewe

Determining the bound energies of dissolved hydrogen on the basis of a multichannel diffusion model in a solid

A hypothesis of the multichannel character of hydrogen diffusion in solids has been substantiated in the paper. Based on this hypothesis, a mathematical model of hydrogen diffusion in the crystalline lattice was constructed. The model allowed determining the dissolved hydrogen binding energies using an extraction curve. The curve is measured by an industrial vacuum-extraction procedure with mass-spectrometric detection of hydrogen streams. The paper presents various experimental data that supports the validity of the multichannel model and discusses the advantages and disadvantages of the proposed approach in comparison with the well-known method of thermal desorption spectra (TDS) that is recognized as the classical way of experimentally determining dissolved hydrogen binding energy in solids

Dry-transfer technique for polymer-free single-walled carbon nanotube saturable absorber on a side polished fiber

We fabricate single-walled carbon nanotube saturable absorbers on a side-polished fiber by a dry transfer technique. We demonstrate that this method allows for the easy and robust implementation of polymer-free carbon nanotube film for an evanescent field interaction in the fiber laser cavity. The high-quality single-walled carbon nanotubes are synthesized by the aerosol CVD method with absorption maximum tuned to an erbium doped fiber laser emission line. The Q-switch and mode-lock regimes as well as the harmonic mode-lock regime with the 79th order are successfully demonstrated with this approach. Critical power for damage threshold is estimated.Peer reviewe