Low Negative Temperature Research Articles

Unveiling the structure-property relationship in a disordered inverse Heusler alloy Ti2MnAl

Search for novel spintronic materials in family of Heusler alloys has attained significant interest in recent years. In this context, Ti2MnAl is interesting as it is predicted to host spin gapless semiconducting state and compensated ferrimagnetic ordering. Here we report a detailed experimental investigation of Ti2MnAl. Our studies reveal that Ti2MnAl crystallizes in cubic structure with strong atomic disorder along with Pauli paramagnetic behaviour. The influence of disorder manifests in form of non-interacting superparamagnetic clusters at low temperatures and negative temperature co-efficient of resistivity. The carrier concentration obtained from Hall resistivity rules out the possibility of spin gapless semiconducting state. Our studies indicate that atomic disorder plays an important role in determination of physical properties of Ti2MnAl.

Economic-biological estimation of pear varieties in the conditions of the steppe zone of the Southern Urals

The paper presents the results of long-term research into winter hardiness, yield, and resistance to scab of introduced pear varieties. The research was carried out in 2021-2023 on collection plots (established in 2002, 2003) of the Orenburg branch of the Federal Horticultural Center for Breeding, Agrotechnology and Nursery in accordance with generally accepted methods. Objects of research included pear varieties ‘Krasnobokaya’ (K), ‘Krasulya’, ‘Vekovaya’, ‘Myth’, ‘Kuibyshevskaya Zolotistaya’, ‘Nezhnost’, ‘Isetskaya Sochnaya’, ‘Lel’, ‘Bolshaya’. The analysis of the obtained data showed that the damaging factors for the pear in the Orenburg region included low negative temperatures and thaws in winter, followed by frosts (2021 and 2023). The maximum degree of freezing (3.0 points) was observed in ‘Kuibyshevskaya Zolotistaya’ and ‘Nezhnost’ varieties in the winter of 2023, affecting their productivity (4.6 t/ha and 5.0 t/ha, respectively). Most of the studied varieties were found to be winter-hardy (slight freezing up to 2.0 points): ‘Krasnobokaya’ (K), ‘Krasulya’, ‘Vekovaya’, ‘Myth’, ‘Isetskaya Sochnaya’, ‘Lel’, ‘Bolshaya’. It was revealed that the maximum average yield for three years of research was obtained in varieties ‘Krasnobokaya’ (K) (8.3 t/ha), ‘Krasulya’ (9.1 t/ha), ‘Vekovaya’ (8.1 t/ha), ‘Myth’ (8.2 t/ha),’ Isetskaya Sochnaya’ (9.7 t/ha), ‘Lel’ (7.9 t/ha), ‘Bolshaya’ (8.5 t/ha). The highest average fruit weight was obtained in varieties ‘Vekovaya’ (120.6 g) and ‘Bolshaya’ (101.2 g). Meanwhile, ‘Bolshaya’ and ‘Lel’ varieties revealed no significant deviations in fruit sizes from the pomological description, unlike the other varieties. It was found that the degree of leaf scab damage varied from 0 (‘Krasulya’, ‘Vekovaya’, ‘Myth’, ‘Bolshaya’) to 2.0 points (‘Kuibyshevskaya Zolotistaya’, ‘Nezhnost’), fruit damage occurred in varieties ‘Nezhnost’ (1.0 point) and ‘Kuibyshevskaya Zolotistaya’ (1.5-2.0 points). Long-term research afforded ground for comprehensive economic and biological evaluation of the introduced pear varieties and identifying valuable samples to be involved in the selection process in the steppe zone of the Southern Urals: ‘Krasnobokaya’ (K), ‘Krasulya’, ‘Vekovaya’, ‘Myth’, ‘Isetskaya Sochnaya’, ‘Lel’, ‘Bolshaya’.

The Effect of a Hot Humid Climate on Corrosion of Reinforced Concrete

The expansion of economic cooperation with countries located in areas with hot, humid climates and the construction of reinforced concrete buildings and structures in coastal zones of non–freezing seas poses the task of assessing the impact of climate on the corrosive state of reinforced concrete structures, primarily carbonation of concrete and seawater aerosol containing chlorides. The effect of low negative temperature is not considered in this work. The data on the carbonation of concrete under conditions of increased insolation and the action of sea salt aerosol are summarized, mainly using the example of the hot humid climate of Cuba for further development of research, and subsequently the development of standards for protection against corrosion and carbonation of concrete and steel reinforcement in areas with a tropical climate. Based on the results of a survey of the condition of reinforced concrete structures and structures manufactured and erected in Cuba, as well as the results of observations, the results of an analysis of aggressive environmental factors of the Republic of Cuba affecting the corrosion of reinforced concrete structures, the results of studies of concrete carbonation and the effects of sea salt aerosol are presented. When designing and building structures on the seashore by domestic organizations in countries with hot, humid climates, the aggressive effects of seawater aerosol and accelerated carbonation of concrete, which reduce the durability of reinforced concrete structures, should be taken into account.

Numerical simulation of the diesel engine starting considering air pre-heating in the intake system

BACKGROUND: Low temperature of the intake air is one of the reasons of difficult starting of a cold diesel engine in conditions of negative outside temperatures. For a reliable staring of a cold diesel engine, it is necessary to have the temperature at the end of the compression stroke higher than the fuel self-ignition temperature. As the temperature at the end of the compression stroke is defined, first, by the temperature at the end of the intake stroke, the mentioned condition can be satisfied with preliminary warming of the air entering in a cylinder. AIMS: The article is devoted to solving the task related to development of a mathematical model of a diesel engine taking into account air pre-heating in the intake system and ensuring simulation of the pre-starting mode, starting and operation of a diesel engine in conditions of low negative outside temperature. METHODS: The enhanced mathematical model of a diesel engine basing on heat mechanics (thermodynamics of opened systems) which reflects main features of an internal combustion engine (ICE) as the system transforming energy in time domain is proposed in the article. The mathematical model’s equation system is based on laws of conservation of energy and mass, solid bodies’ motion equation and includes differential equations of changing of temperature and density of the working body in a cylinder, in the intake system and in the ICE’s crankcase, the ideal gas state equation as well as differential equations of changing of rotation velocity and rotation angle of an engine’s crankshaft. RESULTS: The mathematical model was tried out on the example of the 1Ch9.5/8.0 multi-purposed air-cooled diesel engine. The results of simulation of the pre-starting mode, starting and operation of the diesel engine taking into account air pre-heating in the intake system are presented in the article. CONCLUSIONS: Implementation of air pre-heating at the intake in the design of diesel engines is the most effective way of ensure starting of the engines at low negative outside temperature. The obtained results help to develop recommendations of choosing power and operation modes of pre-heating devices for ensuring starting and operation of diesel engines in conditions of low negative outside temperatures.

The photosynthetic apparatus of the moss Hylocomium lucidum is resistant to low extreme temperatures

The influence of positive and negative temperatures, as well as dehydration/rehydration on the maximum photochemical efficiency, the rate of electron transfer in photosystem II and non-photochemical quenching of the moss Hylocomium splendens, widespread in the boreal forests of the Northern Hemisphere, is shown. It was found that this moss is resistant to low negative (–20 and –80°C) temperatures and significant water losses. On the contrary, in the hydrated state it is unstable to prolonged exposure to positive temperatures (40°C). High resistance to low temperatures and dehydration allowed H. splendens to successfully adapt to growing in northern latitudes and occupy a wide range.

Operation features of aviation tankers in the conditions of the Far North

Huge territories of the Russian Federation are occupied by permafrost. Often aviation is the only mode of transport that connects remote north areas of the country with the rest of Russia. The main feature of permafrost regions is the harsh climate, which includes low negative temperatures, an abundance of snow and strong winds. Such conditions make it extremely difficult to operate ground vehicles that service and maintain flights. In recent years, more and more domestic tankers have been exhausting their life span. At present, a significant number of northern refueling complexes have switched to the operation of foreign tankers based on Volvo and Mercedes-Benz tractors. The operation of these vehicles has already revealed a series of shortcomings which extremely complicate the normal procedures. There is an acute need to refine the components and assemblies in order to reduce the failures that affect the regularity and safety of aircraft flights. One of the main problems of fuel tankers operation at low temperatures is the malfunction of the electropneumatic bottom valve, due to its freezing. The paper proposed replacing this problematic node with a mechanical bottom valve, which is not susceptible to low temperatures. In order to avoid cracking of rubber products of the underwing refueling nozzle and to increase the flexibility of the dispensing hoses, it is proposed to carry out heating of the glass of the refueling nozzle and the filling module by means of exhaust gas bypass and pumping hot coolant through the system of nozzles. The most serious problems are the difficulties of operating a diesel-powered tractor at low temperatures. Problems arise already at startup. Diesel fuel at low subzero temperatures can thicken or even solidify, the lubricant also thickens. There have been cases when the startup was complicated by low compression in the cylinders. But even if the engine was able to start, after a while it may start to stall. This is due to oxygen starvation, which occurs because the icy air entrains water, which is deposited as frost on the air filters, thereby blocking the oxygen supply to the engine. After prolonged parking at low temperatures, during the first seconds of starting the piston engine, the parts come into contact with each other without lubrication. The reason is the viscosity of the oil which decreases at extremely low temperatures, therefore, in order for the lubricant to reach the end users through narrow oil pipelines, it takes some time to warm up (about 10 minutes). As a result of such cold starts and the risk of bullying on the parts of the piston group, their durability is reduced by more than 40%. When starting cold, the engine additionally warms up itself at higher idle speeds. To prevent undesirable consequences, as well as to create more favorable conditions for starting the diesel unit, reducing fuel consumption, it is proposed to use a pre-heater with an external power source from the 220 V electrical network. In order to facilitate the start of the diesel engine, it is necessary to provide the heating of the fuel line and fuel pump filters. To eliminate oxygen starvation of the engine, due to the formation of frost on the filter elements, and to increase the stability of the engine, it is necessary to provide the heating of the air filter.

Effect of Negative Temperatures on the Strength and Deformability of a Reinforced Concrete Element

One of the main components of the economic development of the Russian Federation is the current trend in the development of the territories of the Far North and the Arctic. The need for such development is enshrined at the state level in various programs. Experiments on the study of the effect of negative temperatures on the operation of reinforcing steel show that with decreasing temperature, an increase in strength and modulus of elasticity is observed. At the same time, there are no unified recommendations on the deformation and strength properties of reinforcement for calculating reinforced concrete structures under conditions of low and ultra-low negative temperatures. RF standards do not take into account the influence of climatic (up to -70°C) and technological (up to -196°C) negative temperatures on the deformation and strength characteristics of reinforcing steel.The purpose of this work was to experimentally study the effect of negative temperatures (up to -196°C) on the deformation-strength properties of reinforcement, concrete and reinforced concrete rod elements. Concrete prisms 10x10x40 cm, samples of reinforcement of a periodic profile of class A400 and reinforced concrete prismatic rods with a section size of 12x18 cm and a reinforcement percentage of 1.45% were taken as prototypes. At the same time, the negative temperature of the tests varied. As a result of the studies carried out with centrally stretched reinforced concrete elements, it was found that lowering the temperature to -165°С leads to an in-crease in the cracking force by 162%; strength by 85%. Empirical dependencies are proposed to determine the deformation-strength characteristics of reinforcing steel, depending on the negative temperature.

Temporal and Spatial Evolution Laws of Freezing Temperature Field in the Inclined Shaft of Water-Rich Sand Layers

This study investigated the distribution and evolution characteristics of the temperature field during the freezing and excavation of inclined shafts, with the freezing open-excavation section of Shengfu Mine’s main inclined shaft (located in Shaanxi Province) as the project background. Utilizing field-measured data and the finite element software COMSOL Multiphysics, a 3D freezing temperature-field numerical calculation model was constructed to examine the temporal and spatial evolutions of the temperature field during the construction of the inclined shaft. The findings showed that after 88 days of freezing, the average temperature of the frozen wall in the open-excavation section was below −12 °C. The frozen wall thickness in the sidewalls of different layers exceeded 4 m, and the thickness at the bottom plate exceeded 5 m, meeting the excavation design requirements. For the same freezing time, the average temperature of the frozen wall in the fine sand layer was 0.28 to 2.39 °C lower than that of the frozen wall in the medium sand layer, and its effective thickness was 0.36 to 0.59 m greater than that in the medium sand layer. When the soil was excavated, and the well side was exposed, a phenomenon known as “heat flow erosion” occurred in the soil at the well-side position, causing the well-side temperature to rise. Nevertheless, this increase was generally limited, and when continuous cooling was applied, the well side could maintain a very low negative temperature level. Consequently, there was no spalling phenomenon. The effective thickness of the frozen wall during excavation did not decrease, with the average temperature remaining below −10 °C. Consequently, there was no large-scale “softening” of the frozen wall during excavation, thus ensuring construction safety. The numerical calculation model in this paper can be used to predict the development law of the freezing temperature field of the water–rich sandy layers in Shengfu Mine and adjust the on–site cooling plan in real time according to the construction progress. This research provides valuable theoretical insights for the optimal design and safe construction of freezing inclined-shaft sinking projects.

Сравнительная оценка новых сортономеров контрольного питомника клевера лУгового двУУкосного диплоидного типа в Условиях Смоленской области

Federation To obtain high and stable yields, the creation of productive, ecologically plastic varieties of red clover is of great importance. A successful solution to the problem is possible with the use of modern sources of breeding-valuable traits that are most appropriate for growing conditions. The purpose of the work is to evaluate promising variety numbers of red clover in the control nursery in comparison with the standard variety in terms of economically valuable traits and properties. For the test cycle of 2021-2022, as a result of the assessment, the most productive numbers of red clover were identified. On moderately acidic, soddy-podzolic soil, with a high content of mobile phosphorus and potassium in the control nursery, 6 varieties of red clover were tested in terms of indicators: height, green mass yield, air-dry matter. In winter, the weather conditions changed from favorable to conducive to the destruction of the cover with subsequent exposure to low negative temperatures. The growing seasons were characterized by elevated temperatures and varying moisture regimes from optimal to dry. Variety Pochinkovets has been a standard zoned in the Central region of the Non-Chernozem zone since 2018. Of the 6 variety numbers, 2 promising ones stood out: T-5 and A-12, which have an increased yield of green mass. (61.0 t/ha and 58.2 t/ha), air-dry weight (15.5 t/ha and 15.6 t/ha). The variety number A-11 (65.5%) stood out with a high percentage for 2 cuts. The selected numbers will be used in the future as new sources in breeding work to develop new varieties of red clover.

ВЛИЯНИЕ СТИМУЛЯТОРОВ КОРНЕОБРАЗОВАНИЯ НА УВЕЛИЧЕНИЕ ВЫХОДА ПОСАДОЧНОГО МАТЕРИАЛА ВИНОГРАДА

When growing high-quality grape seedlings, an effective organization of production is required, aimed at the intensification and development of the industry. Rooting grapes with lignified cuttings is one of the most effective and economical methods of reproduction. The article presents the results of three-year studies (2019-2021) to study the effect of biologically active substances on the rootability of lignified grape cuttings. The object of the study is the Victoria grape variety obtained by crossing Vitis amurensis and Vitis vinifera with the Save Vilar 12-304 variety in VNIIVIV im. Yakov Ivanovich Potapenko. The variety under study is a table variety with an early ripening period, characterized by increased resistance to powdery mildew, oidium and gray rot. Withstands low negative temperatures up to -26 ... - 27ºC, with a period from budding to removable ripeness of 115-120 days. During the experiment, records were made about the growth of callus, rooting and output of standard seedlings. When studying the effect of biologically active substances on lignified cuttings, they were treated with salicylic and β-indolyl butyric acids at concentrations of 2000 and 3000 mg/l. As a result of the conducted studies, it was found that the highest percentage of rooting was obtained in the variant using salicylic acid at a concentration of 2000 mg/l and reached 84.5% on average over three years. The same version of the experiment showed the maximum yield of standard seedlings - up to 76.3% on average for three years.

Поліморфізм мікросателітних локусів хромосоми 5H ячменю (Hordeum vulgare L.) і асоціації алелів з морозостійкістю

Barley (Hordeum vulgare L.) is a crop of great economic importance for many countries of the world, including Ukraine. One of the main reason limiting barley production in different regions of Ukraine is low-temperature stress. Prediction of frost resistance in the development and choice of resistant genotypes is one of the main tasks of the breeding. Applying the tools of molecular genetic analysis involves increasing the efficiency of traditional methods of identification and genotype screening with the necessary traits in a specific climatic area. The 5H chromosomal loci are a component of a complex system of genes involved in the formation of resistance to low negative temperatures. The polymorphism and allele distribution of nine microsatellite loci in chromosome 5H, which are localisation in the region of the key NT- resistance genes Fr-H1, Fr-H2 and close to these regions in 35 varieties of the autumn barley collection, were studied. Allelic polymorphism with the presence of two (UMB702) to five (Bmag0223) alleles was detected at the loci Bmag0223, Bmag0323, Bmag0760, GMS061 and UMB702. The frost resistance of 31 varieties with different durations of hardening was evaluated and essential differences between them were noted for this feature. According to the results of the analysis of polymorphism of microsatellite loci and data on evaluation of varieties for frost resistance, the connection of allelic differences of four out of five polymorphic loci with the level of frost resistance and hardening rates was revealed. Reliable associations were established between the presence of alleles Bmag0223, Bmag0323, Bmag0760, GMS061 and indicators of the level of frost resistance. Allelic differences at the UMB702 locus were not associated with differences in any of the traits. Alleles of the microsatellite locus Bmag0223 are recommended for negative choice of less frost-resistant barley genotypes at the early plant breeding stages.

Development and investigation of the properties of frost-resistant high-modulus elastomers reinforced with basalt-, glass- and carbon fabrics

An urgent task in materials science is the development of frost-resistant materials based on elastomers with increased strength and high resistance to shear failure. Obtaining these materials can be achieved by reinforcing with fabrics from various fibers. The most common reinforcing fillers used in polymer composite materials are basalt, glass, and carbon fibers. In this work, composite elastomers based on frost-resistant cis-butadiene rubber reinforced with high-strength fabrics obtained by layer-by-layer stacking were studied. The results of elastic-strength tests showed a 1.7 to 2.8 times increase in tensile strength compared to the original elastomer. At the same time, there is a decrease in elasticity from 25 to 47 times. The results of the study of the structure and adhesive strength suggest low contact between the substrate and the adhesive. This fact is confirmed by the IR spectra, where new peaks are not observed. The study of thermodynamic properties by differential scanning calorimetry and thermomechanical analysis showed the preservation of frost resistance and mobility of the obtained composite elastomers at low negative temperatures.

Use of the peroxidase enzyme to diagnose the resistance of grape varieties (Vitis vinifera L.) to low temperatures

Despite the global trend of the increase in average annual air temperatures observed in recent years, the recurrence of stressful negative temperatures in winter has increased in the southern region of the Russian Federation, and, therefore, the problems of grape frost resistance remain relevant. Low-temperature stresses lead to serious damage and a decrease in vine yields. In order to distinguish the most resistant grape varieties, it is necessary to carry out plant research on the physiological and biochemical level. The paper presents the results of research related to the study of resistance to low negative temperatures of grape varieties of different ecological and geographical groups according to the activity of peroxidase enzyme and its isoforms. The research objects were grape varieties (interspecific hybrids) of European-American origin – Dostoyny, Krasnostop AZOS, Vostorg; of Western European origin – Aligote; of Eastern European origin – Zarif; of Euro-Amur-American origin – Kristall. The study was aimed at exploring the activity of peroxidase and its isoforms and, based on the research results, identifying grape varieties most resistant to low temperatures under the conditions of the southern region of Russia. According to the obtained data on peroxidase activity and electrophoretic separation of peroxidases in polyacrylamide gel, most resistant and less resistant grape varieties to low negative temperatures were identified. The resistant varieties Kristall, Krasnostop AZOS, Vostorg were characterized by a weak increase in peroxidase activity during autumn-winter period (1.1-1.4 times), higher number of isoforms, and their qualitative composition. The less resistant grape varieties Dostoyny, Aligote, and Zarif were characterized by a greater increase in peroxidase activity (1.7- 2.4 times), a small number of isoforms, and their disappearance under conditions of artificial stress. Based on the results, it can be concluded that the study of peroxidase activity and changes in isoperoxidase spectrum in grapevine shoots can be used as diagnostic criteria for assessment of grape varieties for their resistance to low negative temperatures in winter period.

Study on Deterioration Effect of Dynamic Mechanical Properties of Granite at Subzero Temperatures

In the present work, through the dynamic impact test of frozen granite, the effect of temperature on the dynamic mechanical performances of granite at high strain rates were investigated. Based on the existing energy and damage theory, the effects of different low temperatures on the energy dissipation, damage variables, and strength of red sandstone are explored. The reasons for the deterioration of granite dynamic mechanical strength at low temperature are studied by combining analyses of fracture morphology. Researched results showed that low temperatures (<-20°C) cause “frostbite” in granite, leading to the sharp decrease of dynamic and macromechanical strength of the rock under a high strain. Under this dynamic disturbance, transient engineering disasters are easy to occur. The analysis of fracture morphology showed that the lower negative temperature results in the formation of cracks among the mineral particles in the granite. Under high strain rate loading, these cracks have poor plastic deformation ability and are easily destabilized and expanded. Moreover, frozen granite tends to be brittle as a whole. With the decrease of negative temperature, its fracture behavior gradually changes from cleavage fracture to transgranular fracture, and the failure mode also changes from tensile failure to shear failure. The coupling effect of impact and the lower negative temperature will cause the quasicleavage of some crystalline minerals, eventually leading to low-stress brittle failure of granite.

GENETIC RESOURCE OF THE BLACKTHORN OR SLOE (PRUNUS SPINOSA L.) WITH VALUABLE ECONOMIC SIGNS FOR BREEDING ON YIELD AND QUALITY

The analysis of literature data allowed to highlight the importance of the plant Prunus spinosa L. as a valuable source material in the selection of stone crops and its fruits as raw materials for the food and pharmaceutical industries. Leading scientists have obtained a significant number of valuable forms and varieties of terrain, in particular in Ukraine created a variety Donets’kyy krupnyy, in the CIS such varieties as Desertnyy, Velykoplidnyy, Sverkhobilnyy, Sladkiy and others. The analysis of theoretical bases revealed that it is important in the selection of Prunus spinosa L. to involve wild species and forms with different ploidy, in particular the use of hexaploid Prunus spinosa L. avoids the stage of pentaploid hybrids in F1. It is noted that fruit juice called blackthorn or sloe is effective for the prevention of intestinal parasites, dysentery, nonspecific colitis, food poisoning, and also has antiviral and antibacterial properties, which is relevant during pandemics. Original data on the results of expeditionary research of the staff of the Institute of Horticulture of NAAS, conducted in the ecosystems of Polissya and Forest-Steppe of Ukraine are highlighted. It is shown that as a result of analytical selection and fruitful cooperation with amateur gardeners, valuable source material of Prunus spinosa L. was selected and studied. Selected clones of Prunus spinosa L. were introduced to the hospital of the Institute of Horticulture of NAAS, where during 2017-2021 it was studied by morphological features and biological properties. It was found that the forms selected in the conditions of Polissya and Northern Forest-Steppe are characterized by tallness (over 2.5 m), resistance to low negative temperatures, large-fruitedness and increased fruit weight (Nosivs’ky 1-17, Nosivsk’y 2-17, Horokhivs’ky 1-20). Forms selected in the conditions of both Western and Eastern Forest-Steppe of Ukraine are characterized by short stature (height up to 1.6 m), absence of thorns, resistance to moisture deficiency in spring and summer, yield and excellent taste and aroma of fruits (Brodivs’ky 17-19, Mukshans’ky 2-14, Poltava late, Halyts’ky 07-21, Poltavs’ky 2-17). Abundant fruiting of new forms of Prunus spinosa L. in 2021 allowed to harvest fruit from them and evaluate the morphological characteristics and biochemical parameters. The obtained data allowed to single out the most valuable in terms of fruit quality and suitability for food production.

Economic and biological assessment of Vaccinium angustifolium ait. in Udmurtia

The work is devoted to the comprehensive study of a new plant for the territory of the Udmurt Republic - Vaccinium angustifolium. Narrow-leaved blueberry is a promising berry shrub for cultivation in Central Russia. The plant is characterized by high winter hardiness and the ability to withstand temperature drops down to –40 °С, it can grow on poor, acidic, waterlogged soils. The aim of the work was to identify the biological characteristics and productivity parameters of V. angustifolium when introduced under the conditions of the Udmurt Republic. The studies were carried out using widely accepted methods. Phenological features, plant growth and development, productivity, frost resistance and winter hardiness were studied, an integral assessment of the viability and prospects of introduction was given. Morphometric characteristics of plants in 2020: plant height – 40.6±3.2 cm, crown diameter – 59.4±3.3 cm, average productivity – 854.7±60.1 g, average berry weight – 0,97±0.10 g. In the conditions of Udmurtia, blueberries showed stable growth with minimal damage to annual shoots and fruit buds in winter. With prolonged low negative temperatures in December in the absence of snow cover, the highest degree of freezing in individual plants was 2 points (weak freezing). According to the long-term assessment of winter hardiness in the field of Udmurtia, narrow-leaved blueberry can be attributed to the group of winter hardy. The use of the integral scale has shown that the introduction of V. angustifolium is promising (prospect group II – promising).

The influence of air temperature on incidence of the Russian Federation population during the second wave of the pandemic COVID-19

The pandemic COVID-19 continues to take dozens of human lives and destabilize the economy on the planet. In this regard study of the patterns of external conditions influence on incidence dynamics will stay relevant for a long time. The existing views about the influence of atmospheric air temperature are controversial, owing to disparities in geological and climatic conditions for its formation. The data about incidence among population in 22 regions of the Russian Federation during the second wave of the coronavirus pandemic have been collected. There are conducted statistical research on the nature and degree of influence of air temperature on incidence of Russian population due to the COVID-19 pandemic. Statistical research of dynamics of ambient air temperature influence on human incidence depending on the latitude were conducted. At low negative temperatures (< –9.84 °C), an increase in air temperature leads, in most cases, to an increase in theincidence of COVID-19. At ambient air temperatures in the range from –9.84 to +25…+ 30° C, an increase in air temperature is most often accompanied by a decrease in the incidence of COVID-19, which is associated with a decrease in the infectious activity of SARS-CoV-2. The authors consider it necessary to conduct laboratory studies of the effect of negative temperatures on the survival and infectious activity of the SARS-CoV-2 virus in Russia, which will make it possible to predict the most dangerous infectious periods and determine methods to reduce the negative consequences of the COVID-19 pandemic. Research results lead to a better understanding of physical meaning of air temperature influence on COVID-19 incidence and give an opportunity to predict the periods of the most dangerous infection conditions.

Повышение технологической эффективности глушения скважин с использованием инновационных технологий

Introduction. The article considers the issue of assessing the technological efficiency of the well killing process, taking into account changes in the reservoir properties of the productive formation when using various compositions of process fluids. Innovative technologies are presented that are used when killing wells in various mining and geological conditions to block the bottomhole formation zone. Materials and methods of research. The study is based on a summary of many years of experience in the field of creation and practical use of process fluids for killing wells and on the results of theoretical, laboratory, bench studies of killing fluids and blocking compositions, performed in specialized scientific laboratories using specialized laboratory equipment according to standard methods for the oil and gas industry. Research results and discussion. The compositions of process fluids are presented, which are easily removed when inducing inflow from the formation, and which allow to provide the required pressure at the bottomhole, as well as to maintain the reservoir properties of the productive formation and prevent its damage. The results of killing wells with the use of various compositions of process fluids with high stability, low filtration, in a wide range of adjustable density and rheological properties, which allow creating the necessary repression on the formation and performing various operations in the well, are considered. The article also provides information on the analytical studies carried out within the framework of the given problem. The results made it possible to draw conclusions regarding the use of various types of fluids for killing oil, gas, gas condensate wells under conditions of abnormally low reservoir pressures and elevated reservoir temperatures. Consideration is given to the liquids with an acidsoluble condensable solid phase, the formation of which in solution is due to the occurrence of physicochemical processes between its components; biopolymer-based liquids containing various fillers and functional additives; viscoelastic compositions reinforced with solid-state lamellar and fibrous particles of organic and mineral origin (for example, bridging additive brand «OM-2C») based on commercially available polymer reagent «Binar»; emulsion-type kill fluids containing surfactants and a hydrocarbon phase. The main rheological and technological parameters, as well as the properties of the proposed process fluids for killing wells, are described. Сonclusions. Based on the study, it was determined that the most promising technology for killing wells under conditions of abnormally low formation pressures is the technology of preliminary blocking of the bottomhole formation zone using special compositions of process fluids with controlled rheological parameters, taking into account the characteristics of the formation, technologically applicable in special climatic conditions with low negative temperatures. It has also been established that ensuring high efficiency of repair work is impossible without performing theoretical calculations and laboratory studies with modeling the process of blocking the bottomhole zone during well killing and subsequent development.

Effect of frequency and temperature on dielectric and impedance characteristics of cerium modified BaMnO3 ceramics

In this paper, we have mainly discussed the electric field (frequency) and thermal (temperature) effect on dielectric, and electrical (impedance, electrical, and conduction) properties of a solid-state reaction technique prepared cerium modified barium manganite (BaMn0.85Ce0.15O3). The dielectric study exhibits high dielectric constant, low tangent loss, dielectric dispersion, and negative temperature coefficient of resistance characteristics which makes the material useful for energy storage devices. Preliminary analysis of the impedance and electric modulus suggests the presence of a non-Debye type of relaxation process and the role of grain and grain boundaries in the resistive and capacitive properties of the material. Both Nyquist and Cole-Cole plots confirm the semiconductor nature of the sample at high temperatures. The fitted Nyquist data with ZSIMPWIN software showed the decrease of bulk resistance from 8.841 × 107Ω (at 25 °C) to 4.085 × 103 Ω (at 500 °C) which also confirms semiconducting properties and may be found suitable applications for sensors. The analysis of ac conductivity suggests the presence of the thermally activated relaxation process in the sample.

Weather Factors and Their Influence on the Adaptive Properties of Winter Wheat Varieties in the Western Forest-Steppe of Ukraine

The yield potential of winter wheat (Triticum aestivum L.) is formed in changing weather conditions and depends on the proposed agro-technological measures, to which the response of a particular variety is different. The purpose of this study was to determine the influence of weather factors on the field germination of soft winter wheat seeds, the growth and development of plants in the autumn and wintering in the zone of the Western Forest-Steppe of Ukraine, by sowing high-quality basic seed, careful soil preparation and the presence of optimum environmental factors. A sufficient level of productive soil moisture, which protects young shoots from possible deficiency after germination and is a long-term source of moisture at the next stages of organogenesis, has a great influence on obtaining friendly and timely shoots. Often overwintering conditions, when plants suffer from low negative temperatures at the beginning and at the end of the winter period, ground ice crust, resumption of vegetation in winter are the causes of freezing, loss, and ultimately a decrease in yield and seed quality. It has been confirmed that an increase in the temperature regime in 244-247°C in the autumn-winter period and the optimal amount of precipitation contribute to sufficient (31.6-34.6 mm) productive soil moisture (0-20 cm), which positively influences the process of germination of soft winter wheat, provides a high percentage of field germination of seeds of varieties (93.8-94.5%), lengthens the autumn development of plants by 3-12 days, which causes 3.5-5.7% higher accumulation of sugar content in the tillering nodes and a high percentage of overwintering (up to 95.5-96.4%). Varieties of the forest-steppe ecological type of soft winter wheat have insignificant phenotypic variability of adaptive traits, therefore, in the production of grain and seed products, it is recommended to give preference to the plant varieties listed in the Register, suitable for distribution in Ukraine for the Forest-Steppe zone, Polissya. The recommendations set out in this scientific work will help agricultural producers of the studied soil and climatic zone to carry out an effective, more ecologically plastic, highly productive variety replacement