Influence Of Negative Temperatures Research Articles

Climatic temperature and precipitation jointly influence body size in species of western rattlesnakes.

Both the metabolic theory of ecology and dynamic energy budget theory predict that climate influences body size through its effects on first-order determinants of energetics: reactive temperatures, carbon resources and oxygen availability. Although oxygen is seldom limiting in terrestrial systems, temperature and resources vary spatially. We used redundancy analyses and variation partitioning to evaluate the influence of climatic temperature, precipitation and their seasonalities on multivariate body size across the distributions of four species of the western rattlesnake group in North America (Crotalus pyrrhus, C. scutulatus, C. oreganus and C. viridis). Most species showed a pattern of increased body size in cooler, mesic climates and decreased body size in warmer, xeric climates. Exceptions to the pattern provided additional context through climatic idiosyncrasies in the distributions of each species. For example, the general pattern of a negative influence of temperature on body size was not apparent for C. oreganus, which ranges across the mildest climates overall among the four species. In contrast to previous studies, we found that seasonality had negligible effects on body size. We suggest that precipitation gradients correlate positively with resource availability in driving intraspecific body size and that temperature compounds this gradient by increasing baseline metabolic demands and restricting activity in particularly warm or otherwise extreme climates.

Study of the properties of pectin substances for the production of healthy food products

The article is devoted to the research in the field of using frozen grapes in the technology of production of products for a healthy diet. The main objectives of the research are to substantiate technological significance of frozen table grapes for the development of functional desserts. To study the influence of negative temperatures on the gelling and complexing ability of pectin substances in frozen grapes with subsequent defrosting of the raw material. The object of the research was table grapes of 5 varieties grown in the Krasnodar region. Experimental studies of technological and biochemical parameters of fresh and frozen grapes in order to study and confirm the use of grapes in the food industry for the development of desserts with different functional areas were carried out on the territory of the Kuban State Agrarian University named after I.T. Trubilin in the laboratories of the Faculty of Food Production and Biotechnology. Biochemical methods of analysis, generally accepted in the food industry, were used as research tools. It is well known that low-temperature freezing helps to maximize the preservation of the nutritional value of plant materials, however, in the health food industry, recipes and technologies for processing frozen grapes are practically not represented. An information search of scientific literature has shown that there are no studies on the study and selection of grape varieties for canning by freezing and the production of functional products from defrosted raw materials, which indicates the need to conduct experimental studies, study the kinetics of the chemical and biochemical composition of fresh, frozen and defrosted grapes in order to differentiate raw materials for the production of desserts with different functional orientations. Using biochemical analysis methods, it has been established that, regardless of varietal characteristics, the main components of the chemical composition of grapes are preserved during freezing and further defrosting.

A Study of the Influence of Negative Temperatures on the Impact Strength of a Carbon-Fiber Composite with a Hybrid Matrix

A Study of the Influence of Negative Temperatures on the Impact Strength of a Carbon-Fiber Composite with a Hybrid Matrix

Using longitudinal critically refracted waves to detect absolute stress of steel members considering the influence of temperature

Longitudinal critically refracted (LCR) waves are widely used to detect the absolute stress of steel members in service. The influence of temperature leads to deviation in absolute stress detection. However, existing methods compensate the detected stress by measuring the variations in the acoustic time at different temperatures in zero-stress specimens, which neglects the influence of temperature under different stresses. This study proposes a new ultrasonic method for detecting the absolute stress of steel members considering the influence of temperature. The most important feature of this method is considering the coupling between temperature and stress. A temperature sensitivity experiment was designed to compare the effects of temperature using a one-transmitter-one-receiver (OTOR) transducer group and a one-transmitter-double-receiver (OTDR) transducer group. The absolute stresses of three steel specimens (Q235B, Q345B, and Q390B) were detected at different temperatures to verify the proposed method. The experiment results indicate that the OTDR transducer group has a lower temperature sensitivity of 2.07 ns/°C compared with 14.16 ns/°C for the OTOR transducer group. Using the OTDR group can effectively reduce the negative influence of temperature and improve detection accuracy. The stress coefficient decreases with increasing temperature, and the temperature coefficient increases with increasing stress, which reflects the coupling of temperature and stress. The deviations of the proposed method are within 10 MPa and far less than the deviation of the traditional method. The proposed method can be used in practical steel structures at different temperatures.

Изменчивость биохимических признаков Pinus sylvestris (Pinaceae) при адаптации форм в условиях избыточного увлажнения

Conifers are characterized by a certain degree of individual variability in the content of stress metabolites, which can be caused by genotypic variations or divergence in the growth conditions of individual trees. The purpose of the study is to evaluate the variation of biochemical traits of Scots pine, which are different in the color of male strobilus, during adaptation to the conditions of constant excessive moisture in the soil of the northern taiga. The dynamics of metabolic parameters of Pinus sylvestris L. were investigated in shrubsphagnum pine stands on marshy upland soils at the mouth of the Northern Dvina River (northern taiga subzone). From July to November 2018, needle samples from shoots were collected from 10 pine trees of each of the male strobilus types, differentiated by color. The contents of photosynthetic pigments, anthocyanins, ascorbic acid, proline, water-soluble proteins, and pH were measured under laboratory conditions. The synthesis of chlorophyll in the needles in the current year of formation decreased in trees of both forms during the dry summer period. A favorable temperature in the autumn period could promote an extension of photosynthetic pigment accumulation, which might negatively affect tree preparation for overwintering. There were no significant differences between f. erythranthera Sanio and f. sulfuranthera Kozubow in the needle content of chlorophyll and carotenoids, anthocyanins, ascorbic acid, free proline, water-soluble proteins, or pH. The similarities in the adaptation of the trees to the constant excessive soil moisture in northern taiga conditions were revealed. The seasonal factor had a considerable impact on the dynamics of biochemical parameters. Ascorbic acid, proline, and anthocyanin were more actively accumulated in the needles throughout the summer due to the high air temperature, resulting in an increase in antioxidant activity and the development of protective mechanisms aimed at reducing oxidative stress. The increase in water-soluble protein content in needles from October to November is one of the cryoprotective mechanisms of the trees for the winter period. Individual differences in ascorbic acid and proline contents in yellow microspore-bearing pine needles at the establishment of minus temperatures in November were considerably higher than in red microspore-bearing pine needles. This is regarded as the norm of the reaction for different types of trees to the influence of negative temperatures. For citation: Tarkhanov S.N., Pinaevskaya E.A., Aganina Y.E., Pakhov A.S. Variability of Biochemical Properties During Adaptation of Pinus sylvestris (Pinaceae) Forms to Excessive Moisture Conditions. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 4, pp. 58–75. (In Russ.). https://doi.org/10.37482/0536-1036-2023-4-58-75

The possibility of using frozen table grapes in the production of functional food products

The article is devoted to the research in the field of the use of frozen grapes in the production of functional products. The main tasks are to substantiate the technological significance of frozen table grapes for the development of recipes for functional products and to investigate the influence of negative temperatures on the change in the quality indicators of raw materials. The objects of the research are 5 table varieties of grapes grown on plantations of the peasant farm of the Dinskoy district of Krasnodar. At the Department of Technology of Storage and Processing of Crop Products of the Kuban State Agrarian University named after I.T. Trubilin, experimental studies of the qualitative characteristics of fresh grapes have been carried out in order to study and confirm the prospects for using frozen grapes for the production of functional products. To perform the research, standard physicochemical and organoleptic methods of analysis, generally accepted in the food industry, have been used. The grape berry is a source of nutrients that the body needs to maintain a full and active lifestyle when consumed fresh: anthocyanins, pectins, vitamins and minerals.The disadvantage of replenishing these nutrients is the short period of consumption of fresh grapes. To study the technological qualities of grapes, varieties with different ripening periods have been studied.Freezing as a preservation method allows these products to be consumed throughout the year. The methods of physical and chemical analysis have been used to determine the indicators of the biochemical composition of fresh and defrost grapes, confirming their biological and nutritional value. It has been established that shock freezing of grapes with subsequent defrosting allows preserving biologically valuable components of the chemical composition of the objects under study, which makes it possible to develop healthy food products from frozen table grapes.

ВЛИЯНИЕ ТЕМПЕРАТУРЫ ПРОМОРАЖИВАНИЯ НА ИНТЕНСИВНОСТЬ ДЕГИДРАЦИИ САПРОПЕЛЯ

The use of sapropel and its derivatives is highlighted as a promising direction for increasing soil fertility. During the preparation and processing of sapropel, one of the operations that allows to reduce its humidity is freezing to negative temperatures. But at the moment there is no information on the required freezing temperature and its effect on the amount of water to be separated. The article presents the results of a study of the process of separation of bound water from solid sapropel particles under the influence of negative temperatures. It was found that to separate the bound water, it is sufficient to cool the sapropel below the freezing point of the water. Further cooling in the range of negative temperatures has no effect on the amount of water to be separated. This effect has been proven experimentally, and the results obtained will reduce the energy intensity of the process.

Исследование прочностных свойств углепластиков с двухфазной схемой армирования

The results of experimental studies of impact strength and tensile strength of carbon fiber plastics with a two-phase reinforcement scheme, including under the influence of negative temperatures (–30 and –50 °C), are presented. A feature of the tested carbon fiber plastic samples is the presence in their structure of an additional reinforcing material (a «liquid» phase material) which is a monomer or polymer and provides an increase in the relaxation characteristics of the composite. Triethylene glycol dimethacrylate, silicone sealant and synthetic wax were used as such material in the work.

Investigation of the influence of negative temperatures on the technological properties of belite sludge

The paper describes the characteristics of belite sludge - a large-tonnage waste of alumina production. The influence of negative temperatures on the technological properties of the sludge was investigated. The regularities of sludge cooling during its excavation, long-term storage and in the technological process of structural layers’ construction in winter conditions have been studied. Recommendations have been developed for the construction of foundations (coatings) from sludge and sludge-mineral materials at temperatures below minus 20°C. The implementation of research results helps to prolong the construction season, reduce material consumption and increase durability during construction, reconstruction and repair of transport infrastructure objects.

Исследование влияния отрицательных температур на напряженно-деформированное состояние клеесварных соединений

The study results for the assessment of the influence of negative temperatures on the change in the stressed-strained state of welded and glue-welded joints made using various types of adhesive materials are presented. An epoxy compound and melt adhesive based on ethylene copolymer with vinyl acetate were used as adhesive materials. Using tomography, it was found that a glue-welded joint made on a melt glue had the best characteristics, both at positive and negative temperatures.

Evaluation of the influence of negative temperature during storage on the quality of food grain

The influence of negative temperatures during storage on the quality and baking properties of food grain was assessed. The effect of constant negative temperature on lipid fractions and baking properties of wheat and the quality of bread was studied. Experimental data on the storage of grain crops in unregulated temperature and humidity conditions of permafrost on the Taimyr Peninsula were analyzed, and the safety and preservation of the technological and baking characteristics of the quality of wheat and rye for a long period (up to 36 years) was confirmed.

HYDRATION AND HEAT RELEASE OF CEMENT HARDENING IN THE COLD

The article provides a comprehensive coverage of the problem of the influence of negative temperatures on the properties and structure of concrete during its early freezing. Studies have established the regularity of the content of the liquid phase in the cement gel at low temperatures, as well as the strength gain of cement. Water under ordinary conditions freezes at 0 ° C, and it would seem to make no sense to talk about cement hydration, but the properties of thin films of water and the change in their physical properties allow cement hydration to occur. Such water freezes at more negative temperatures, and being in a liquid state can react with cement minerals

Влияние температуры окружающей среды на инкубационный период и склонность угля к самовозгоранию

Crushing coal during mining significantly increases the contact area of combustible components with atmospheric oxygen. The heat released during coal oxidation can lead to an increase in the temperature of the coal accumulation and the appearance of places of spontaneous combustion. For the timely prevention of endogenous fires, it is required to know the incubation period of spontaneous combustion, which is necessary for the coal accumulation to reach the critical temperature. Based on this parameter, the category of coal propensity to spontaneous combustion is established, and measures are developed to reduce the endogenous fire hazard. The known method for estimating the incubation period does not sufficiently consider the influence of the environmental parameters on coal heating. The discrepancy between the calculated and actual duration is observed for coal at a negative temperature, for example, in the mines, and the open-casts in the permafrost areas, as well as in the warehouses in winter on a significantly large territory of Russia. Studies showed that a decrease in temperature significantly reduces the rate constant of oxygen sorption by the coal, and the release of heat in the coal accumulation. The process of spontaneous combustion of coal also slows down due to additional heat losses for the phase transition of water from solid to liquid state. For improving the accuracy of calculating the incubation period of spontaneous combustion of coal at negative temperatures, it is proposed to consider the specific heat of melting ice, and to determine the oxygen sorption rate constant at a constant temperature from –10 to –20 ° C. The influence of negative temperatures of coal accumulation increases the incubation period of spontaneous combustion of coal by 2–3 times allowing to reduce the cost of measures to prevent endogenous fires.

Thermal and hydrodynamic behavior of forced convection gaseous slip flow in a Kelvin cell metal foam

Porous metallic foams are a key material in numerous thermal and hydraulic applications. Gas flows in such micro/nanoporous systems deviate from classical continuum descriptions due to nonequilibrium in gas dynamics, and the resulted heat and mass transport show variation by rarefaction. This study performed a wide range of pore-level analysis of convective gas flows in a Kelvin cell model at different porosities and working conditions. Rarefaction effects onto permeability and heat transfer coefficients were calculated through Darcy to Forchheimer flow regimes. Permeability increased up to 60% by increasing rarefaction while this enhancement decreased by increasing porosity. At the same time, rarefaction lessened inertial effects such that Forchheimer coefficients decreased substantially. At high flow velocities, the increase in rarefaction considerably decreased the effect of drag forces. Hence, hydrodynamic enhancement due to rarefaction was found to increase by increasing Reynolds number. On the other hand, positive influence of boundary slip and negative influence of temperature jump developing between gas and solid almost canceled each other for the studied low heat flux region of highly conductive metal foam structures. Hence, Nusselt numbers were found mostly related to Reynolds number independent from rarefaction. We described Nusselt value based on power law model as a function of Reynolds and porosity. Results and the proposed model are important to accurately predict the thermal and hydrodynamic performance of metal foams in the 80 PPI range.

Equilibrium and Hysteresis Formation of Water Vapor Adsorption on Microporous Adsorbents: Effect of Adsorbent Properties and Temperature

Water vapor has been one of the vital problems in purification of volatile organic compounds. In this study, the adsorption-desorption equilibrium of water vapor were conducted at 298, 308, 318 and 328K on three adsorbents: hypercrosslinked polymeric adsorbents (HPA), activated carbon fiber (ACF) and granular activated carbon (GAC). The obtained isotherms were type V and the adsorption capacity at the same condition was as follows: GAC>ACF>HPA. Cluster Formation Induced Micro-pore Filling (CIMF) model was adopted to fit the adsorption isotherms and the fitting parameters showed that adsorption capacities of water vapor on micropores and functional groups had a negative logarithmic linear relationship with temperature. The existence of functional groups could weaken the negative influence of temperature on the water adsorption performance, while the influence of temperature had negligible relationship with microporous volume. The hysteresis loops at different temperatures on three adsorbents had similar shape, the size of which were also as follows: GAC>ACF>HPA. They mainly occurred in micropore adsorption, but their size had positive relationships with both functional groups and microporous volume. The hysteresis became smaller along with the increase of temperature, closely related with the stability of water clusters. In conclusion, temperature, functional groups and porous structure played crucial roles for water vapor adsorption and the formation of hysteresis.

Integrity Analysis of the Sheath Considering Temperature Effect under Deep and Large-Scale Multi-Section Hydraulic Fracturing

Different operations make the borehole temperature change and cause periodic stresses, which often cause variations in the stress state of the sheath or damage. In this paper, the effect of temperature on sheath integrity is investigated. First, the mechanical model of sheath is established and analyzed by shakedown theory. Then, compression experiments of well cement at different temperatures are carried out, and the law of mechanical properties with temperature is obtained. Finally, combining the theoretical analysis and mechanical experiments, the results show that (1) when only the temperature inside the sheath cyclically varies, the negative influence of temperature caused by the practical operations can be negligible. (2) When the internal pressure and temperature act together, the effect of temperature on the sheath is reflected in temperature stress and the change of the cement properties. (3) With the increase of temperature difference (∆T), the cohesion of cement decreases while the internal friction angle increases, and the plasticity characteristics of the cement are enhanced, and the negative effect on the Pmax ascends slowly. (4) The temperature stress is in a positive relationship with the ∆T, and its weakening on the Pmax is about 6% to 7%. (5) Combining the temperature stress and the change of the cement properties, total negative effect of temperature on the sheath accounts for 10% to 12%, when ∆T ranges from 60 to 110 °C.

Analysis of the Negative Daily Temperatures Influence on the Failure Rate of the Water Supply Network

As a part of the critical infrastructure, water supply systems must be characterized by an appropriate level of operational reliability and safety. One of the threats to this is the failure of the water supply network, influenced by many factors, among which we can distinguish internal factors related to the process of designing, construction and system operation, and external factors related to the impact of the environment. The paper presents the influence of negative daily temperature on the failure rate of the water supply network, taking into account the material of the pipes, their diameters, and the cause of failure. The research was carried out on operational data from the period 2004–2018 from the water supply network in a city located in south-eastern Poland. The relationship between the daily temperature and the failure rate of the water supply system has been shown. As the temperature values drop, the failure rate values increase. The biggest influence of the negative daily temperature on the water supply network failure rate is observed for cast iron pipes. PE and PVC pipes are more resistant to the influence of negative temperatures. The most common cause of failure is corrosion and unsealing of the pipes. Pipes with the diameters of 100, 150, 300, 350, and 400 mm in distribution and main networks turned out to fail most often. These results can be used by water supply companies to limit the influence of factors related to negative daily temperatures on the failure rate of the water supply network.

Estimation of the possibility of using anaerobic impregnating compositions to increase frost resistance of rubber suspension elements of road vehicles

The conditions of operation of non-metallic elements of air suspension of road vehicles are analyzed. The influence of negative temperatures on non-metallic (rubber) elements of an air spring has been studied. An assessment of the possibility of using impregnating compositions for servicing the rubber elements of the air suspension of road vehicles in various temperature conditions has been carried out. It is shown that the use of impregnating compositions when servicing rubber elements of an air suspension allows minimizing cracking of the material and, consequently, increasing the durability of the suspension.

Evaluation of the strength characteristics of non-metallic elements of the air suspension of machines under the influence of negative temperatures and aggressive environments

The operating conditions of non-metallic elements of the air suspension of road vehicles are analyzed. The influence of deicing agents and negative temperatures on non-metallic (rubber) elements of the pneumatic spring is studied. The methods of conducting tests to assess the effect of negative temperatures and aggressive environments on non-metallic elements of the air suspension are described. It is shown that the destruction of the microstructure is caused by the action of reagents on the rubber part of the pneumatic cylinder. Keywords: road vehicles, air suspension, rubber elements, negative temperatures, deicing agent

Оценка стойкости неметаллических элементов пневматической подвески машин к воздействию отрицательных температур

The operation conditions of nonmetallic elements of the pneumatic suspension of road-making machines have been studied and analyzed. Evaluation of the strength characteristics of the nonmetallic elements of the pneumatic suspension under the influence of negative temperatures was carried out. It was found out by experiments that the influence of negative temperatures resulted in an increase in stiffness of a rubber part of an air cell. It was determined that for increasing resistance of the nonmetallic elements of the pneumatic suspension to the influence of negative temperatures it was necessary to use anaerobic impregnating compounds.