Level Of Heat Resistance Research Articles

Features of reproductive capacity and state of prooxidant-antioxidant homeo-stasis in breeding boars of different breeds

Temperature stress is caused by the long-term effect of high or low average daily temperature, which leads to a decrease in the quality of sperm in fetuses and processes from the formation of the leading herd of pigs, which causes a reduction in the production of livestock products. Changes in lipid peroxidation accompany the inhibition of reproductive function in breeding boars of various breeds. The research method was to determine the features of pro-oxidant-antioxidant homeostasis in breeding boars of different species depending on the keeping conditions. For the experiment, six breeding boars of other breeds, similar in age, live weight, and quality of sperm production, were selected, and 2 study groups of 3 heads in the skin were formed. The first group consisted of animals of the large white breed, and the second group – was from Myrhorod. Animals were fed following feed regulations. The influence of heat stress on the quality of sperm production of breeding boars of the large white breed is manifested in a decrease in the following indicators: ejaculate volume – by 20.3 %, sperm motility – by 20.6 %, sperm concentration – by 28.3 %, the number of live sperm – by 54.6 %, heat resistance by 26.4 %. As the temperature rises, peroxidation processes accelerate – the content of TBC-active compounds in sperm increases by 1.3 times. Catalase activity in seminal plasma and sperm increases by 16.0 % and 21.0 %, respectively. An increase in indoor temperature harms the indicators of sperm production of breeding boars of the Myrhorod breed: ejaculate volume – by 18.6 %, sperm motility – by 10.5%, sperm concentration – by 30.3 %, number of live sperm – by 34.7 %, thermal resistance – by 23.5 %. The changes occur against the background of an increase in superoxide dismutase activity – 21.0 % (sperm) and 5.0 % (sperm plasma), a decrease in ascorbic acid saturation by 10.0 % and 52.2 %, respectively. The establishment of an interbreed difference in the quality of ejaculates in the direction of the superiority of indicators in animals of the large white breed compared to the Myrhorod breed on the 60th day of the primary period in the summer in terms of ejaculate volume (p = 0.001) and sperm concentration was established. However, according to the level of heat resistance of sperm, animals of the second breed were characterized by higher values. At the end of the 45th day of temperature stress, a probable predominance of ascorbic acid (p = 0.001) and dehydroascorbic acid (p = 0.01) content was observed in the semen of animals of the Myrhorod breed compared to large white.

The influence of temperature on variability of male gametophyt traits in the progeny of virus-infected tomato genotypes

The action of the thermal factor on the functionality of the male gametophyte in tomato progeny infected with tobacco mosaic virus (TMV) and tomato aspermia virus (TAV) was studied. It was established that the influence of high temperature on the male gametophyte in TMV/TAV offspring causes the modification of the functional characters of the male gametophyte. The effect produced is largely controlled by temperature 78.1...81.5% (for pollen viability), and the variation of pollen tubes sizes is determined by temperature and the interaction of factors (75.6%). The individual analysis of the structures of the variation spectra of the male gametophyte index for each genotype revealed significant differences in their sensitivity to the action of the factor that cause variability, a fact that allowed to the clustered of genotypes according to their reaction to stress, as well as the prediction of the sporophyte response to the stress. Based on the obtained data, genotypes with a high level of heat resistance were highlighted for their subsequent inclusion in the improvement process.

INVESTIGATION OF THE HEAT TREATMENT MODES EFFECT ON THE STRUCTURE AND PROPERTIES OF A FIREPROOF MAGNESIUM CASTING ALLOY OF THE Mg-REM-Zr SYSTEM

The research results on the development of a new generation Mg-REM-Zr fire-safe magnesium casting alloy system are presented. Serial magnesium alloys do not have both high strength at room temperature and a sufficient level of heat resistance. A unique domestic foundry magnesium alloy has been developed with consistently high specified properties at the same time. In addition, the obtained ignition temperature indicators of the developed alloy allow it to be attributed to the group of fireproof magnesium alloys. The conducted studies of the its heat treatment parameters made it possible to choose the optimal mode that ensures the achievement of high strength characteristics of the alloy.

Improving thermo-tolerance of Saccharomyces cerevisiae by precise regulation of the expression of small HSP

The level of heat resistance in microbial cells is an important factor in determining the energy consumption and product synthesis efficiency of fermentation processes.

Dry heat sterilization modelling for spacecraft applications.

Inactivation processes using heat are widely used for disinfection and sterilization. Dry heat sterilization of spacecraft equipment has been the preferred microbial inactivation method as part of interplanetary travel protection strategies. An antimicrobial model, based on temperature and exposure time based on experimental data, was developed to provide reliable sterilization processes to be used for interplanetary applications. Bacillus atrophaeus spores, traditionally used to challenge dry heat sterilization processes, were tested over a range of temperatures in comparison with spores of Bacillus canaveralius that have been shown to have a higher heat resistance profile. D-value and Z-values were determined and used to develop a mathematical model for parametric sterilization applications. The impact of the presence of a contaminating soil, representative of Mars dust, was also tested to verify the practical application of the model to reduce the risk of microbial contamination in such environments. The sterilization model developed can be used as an intrinsic part of risk reduction strategies for interplanetary protection. Forward and backward planetary protection strategies to reduce the risks of microbial contamination during interplanetary exploration and research is an important consideration. The development of a modern sterilization model, with consideration of microorganisms identified with higher levels of heat resistance than traditionally deployed in terrestrial applications, allows for the consideration of optimal inactivation processes to define minimum criteria for engineering design. The ability to inactivate living microorganisms, as well as to degrade biomolecules, provides a reliable method to reduce the risk of known and potentially unknown contaminants in future applications.

Prospects for the Use of Fluorinated Nanodiamonds in the Synthesis of Superhard Composites

The paper considers the possibilities of the practical use of nanoscale diamonds with a fluorine-functionalized surface for the synthesis of diamond composites under high pressures and temperatures. Optimal compositions of the initial mixtures and parameters of thermobaric treatment are established. It is shown that composites obtained by sintering homogeneous mixtures of fluorinated microdiamonds and nanodiamonds with the addition of aluminum and cobalt have an increased level of heat resistance and wear resistance which significantly exceeds the level of commercial samples.

Development and characterization of protective gloves using waste para aramid fibers

Increasing levels of textile waste have become a matter of great concern for the environment and the circular economy movement. Synthetic or man-made fibers are not decomposed in landfills and also generate toxic gases if incinerated. Waste of high-performance fibers has enormous potential to be used in the development of technical products. In this study, carding waste of para-aramid fibers was blended with virgin polyester fibers to produce needle punched nonwoven felts to be used in the development of protective gloves. Nonwoven webs of different blend ratios and three different weights (GSM) (100, 150, 200 g/m2) were produced. The nonwoven webs were then quilted with knitted polyester fabric to produce gloves. Cut resistance, abrasion resistance, tear resistance and heat resistance of the felts increased with the increase in GSM (g/m2). Particularly at lower GSM, an increasing percentage of aramid fibers showed significant enhancement in cut resistance. The nonwoven felts comprising aramid/polyester blends of 75/25 and 60/40 yielded level 3 cut resistance at 100 GSM which reduced to level 2 with a further decrease in aramid fiber content. The abrasion resistance and tear resistance of the gloves were at level 3 to 4 and showed little dependence on blend ratio but were relatively higher at higher GSM. At 100 GSM, the felts exhibited heat resistance level 1 which increased to level 2 at 200 GSM. The findings of this study suggest that waste of high-performance fibers can be used as cost control and environmentally friendly strategy in the development of protective textiles.

Weathering performance and structural characterization of limestone–polyethersulfone composites

Using limestone powder as an aggregate and polyethersulfone (PES) powder as a binder, the limestone: PES composite material, LPES, with a mass fraction ratio of 1:10 was prepared using the SLS technology. The sintered parts were subjected to the xenon lamp aging, thermal analysis, cross-sectional scanning electron microscope (SEM) tests. The results showed that the LPES material sintered parts aged slower, and had a longer service life. Compared with the sintered parts of pure PES material after aging for 10 weeks, the service life of LPES was increased by 38.91%, and with the filling of limestone powder material, the decomposition temperature and heat resistance level of LPES composites were effectively improved. In addition, the heat absorption of LPES composites during decomposition was reduced.

The reference genome and full-length transcriptome of pakchoi provide insights into cuticle formation and heat adaption.

Brassica rapa includes various vegetables with high economic value. Among them, green petiole type pakchoi (B. rapa ssp. chinensis) is one of the major vegetables grown in southern China. Compared with other B. rapa varieties, green petiole type pakchoi shows a higher level of heat resistance, which is partially derived from the rich epicuticular wax. Here we sequence a high-quality genome of green petiole type pakchoi, which has been widely used as the parent in breeding. Our results reveal that long terminal repeat retrotransposon insertion plays critical roles in promoting the genome expansion and transcriptional diversity of pakchoi genes through preferential insertions, particularly in cuticle biosynthetic genes. After whole-genome triplication, over-retained pakchoi genes escape stringent selection pressure, and among them a set of cuticle-related genes are retained. Using bulked-segregant analysis of a heat-resistant pakchoi cultivar, we identify a frame-shift deletion across the third exon and the subsequent intron of BrcCER1 in candidate regions. Using Nanopore long-read sequencing, we analyze the full-length transcriptome of two pakchoi cultivars with opposite sensitivity to high temperature. We find that the heat-resistant pakchoi cultivar can mitigate heat-caused leaf damage by activating an unfolded protein response, as well as by inhibiting chloroplast development and energy metabolism, which are presumably mediated by both transcriptional regulation and splicing factors. Our study provides valuable resources for Brassica functional genomics and breeding research, and deepens our understanding of plant stress resistance.

Heat Treatment and Properties of High-Temperature Steels for Rolling Bearings

Abstract It is demonstrated that high speed steels are suitable for manufacturing of heat resistant rolling element bearings especially for applications in aero engines. A detailed analysis of heat treating processes and metallurgical evaluation shows how the properties of these steels grades can be adjusted to meet the specific requirements for engine bearings. Based on results from rig testing it is shown how variations in heat treating parameters can influence the rolling contact fatigue performance. The role of carbides, a typical constituent of high speed steels, on bearing applications is discussed in detail. The high level of heat resistance of high speed steels allows a nitriding in addition to the conventional heat treatment. By nitriding an increase in hardness close to the surface can be achieved which can make bearings more robust against indentation of hard particles. ◼

Understanding the effect produced by combined processing and drawing on the structure and properties of conductive semi-finished products made of Al – Zr alloys

The results of experimental studies of the properties of an experimental batch of deformed semi-finished products from alloys of the Al – Zr system, made using the methods of combined processing and drawing, are presented. The influence of combined casting, rolling-extrusion and drawing conditions on the mechanical properties and electrical resistivity of deformed semi-finished products for electrical purposes with different zirconium and iron contents is studied. The rational modes of joint hot and cold machining of the alloys under study have been determined, which make it possible to achieve high strength, ductility and electrical conductivity of conductive semi-finished products. The microstructure of the experimental samples was analyzed with a light microscope, the influence of combined casting and rolling-extruding and cold-drawing modes on the metal flow pattern and phase distribution in the structure of rods and wire was established. Temperature tests of an experimental batch of deformed semifinished products after hot and cold machining were carried out in accordance with the international standard IEC 62004–07. The level of heat resistance of manufactured rods and wire when heated to operating temperatures is set. The regularities of the change in the temporary resistance to rupture and the relative elongation of the test samples after temperature tests are determined depending on the different conditions of combined casting, rolling-pressing and cold drawing. Recommendations on the content of alloys and modes of production of rods and wire with a stable structure during heating and a given level of operational properties of cable and conductive semi-finished products were formulated. Application of the technological scheme using the methods of combined casting, rolling-extruding and drawing allows to obtain the required level of strength properties and heat resistance of semi-finished products from aluminum alloys of the Al – Zr system with different iron content.

Influence of high-temperature convective flow on viability of Scots pine needles (Pinus sylvestris L.)

During a forest fire, plants are affected by high temperatures causing stress. At the time of burning, it is difficult to record temperature changes in tree crowns and the associated effects on photosynthesis. This paper presents the results of modelling a high-temperature effect simulating a convective flow from a ground fire. Evaluation of the response was carried out by the parameters of rapid fluorescence (Fv/Fm, ETR), the state of the pigment complex, and the relative water content in the needles. To characterize the degree of heat endurance and short-term effects concerning thermal damage, saplings of Scots pine (Pinus sylvestris L.) were used at different times during the growing season (June, July, August, September). Experimental heating at 55 °C lasted for 5 and 10 min. There were different levels of heat resistance by the needles. Data in June show that heating of the saplings significantly suppressed photosynthesis. In July, August, and September, the photochemical quantum yield (Fv/Fm) was restored to 75% and 60% from the initial level after 5- and 10-min heating, respectively. The electron transport rate (ETR) for saplings in September was restored to their initial level within 3 days after a short heat exposure. Restoration of the photosynthetic activity in needles was observed after a 5-min impact, but by the end of the study period, restoration had not reached control values. A longer heating of 10 min resulted in an irreversible suppression of photosynthesis and destruction of the photosynthetic apparatus, as evidenced by the decrease in the number of photosynthetic pigments.

Study of physicochemical stability of anthocyanin extracts from black peanut skin and their digestion enzyme and adipogenesis inhibitory activities

In this study, the physicochemical stability, and the digestive enzymes inhibitory potential of anthocyanins in black peanuts skins (BPS) were evaluated. Cyanidin-3-O-sophoroside (C3So) and cyanidin-3-O-sambubioside (C3Sa) were identified as the main anthocyanins in BPS. The anthocyanins extract showed a certain level of heat resistance. During the storage period (37 °C for 4 weeks), anthocyanins were stable and with a projected half-life of 66.59 days when the pH was 2.5. These results indicated that the anthocyanin from BPS presented higher thermal stability. Moreover, Anthocyanin-rich extracts could inhibit the main digestive enzymes, with the IC50 values were 185.1 μg/ml (pancreatic lipase), 123.4 μg/ml (α-amylase), and 82.75 μg/ml (α-glucosidase), respectively. The in vitro cell study also indicated anthocyanins from back peanut skin showed a strong antiadipogenesis potential in 3T3-L1 cells by inhibiting the expression of the key adipogenic transcription factors and related genes. This research highlights the opportunity that black peanut skin could be considered as a promising resource of anthocyanins as a natural food colorant with multifunction properties.

Variety changing of winter soft wheat as a method to improve productivity and resistance to abiotic environmental factors

The article deals with the use of variety changing to increase productivity and resistance of winter wheat varieties to abiotic environmental factors. As a result of the variety changing and sequence of varieties successively replacing each other, the productivity increased from 3.3 t/ha (stage I) to 6.2 t/ha (stage VII). It has been established that the varieties belonging to the steppe ecotype possess a higher level of drought resistance in comparison with the varieties of the forest-steppe ecotype. According to the stages of variety changing drought tolerance ranged from 69–70% (stage I) to 95–99% (stage VII). The level of heat resistance from I to V stage of the variety changing was low (48–70%), excluding the variety “Rostovskaya” (III stage of variety changing) with its heat resistance of 81%. The varieties of the sixth and seventh stage of the variety changing possess high heat resistance (90–99%). The replacement of the cultivated varieties with new, more adaptive and highly productive ones will allow stabilizing grain production and rising its quantity.

The Challenges in Development of Nickel-Based Heat-Resistant Superalloys for Gas Turbine Disks and Creation of a New Superalloy with Increased Operational Characteristics

The report presents the results of works on creation of new disk superalloy with ultimate tensile strength σB20 exceeding 1700 MPa, satisfactory ductility and high level of heat resistance – its creep rupture strength is σ100650≈1235 MPa. By the obtained properties, the superalloy is superior to all known domestic and foreign analogues.The structure examination results have been given which prove the optimum morphology of strengthening γ'-phase precipitates, absence of deleterious phases and high structural stability.

Predictable and unpredictable survival of foodborne pathogens during non-isothermal heating

In previous work, extreme survival of various bacterial species during cooking was reported when attached to chicken meat. In this paper the effects of an extremely high challenge temperature on survival of Salmonella Typhimurium and Campylobacter jejuni, attached to chicken breast fillets or pork to test for matrix effects are reported. Survival was predicted, using standard D- and z-values from the literature, and compared to experimentally obtained data. Attached to meat, both S. Typhimurium and C. jejuni survived longer than predicted, longer when attached to chicken meat than when attached to pork.Additionally, the effect of non-isothermal heating on survival of almonella in buffer is described. In buffer, when slowly heated, Salmonella died off as predicted. When Salmonella was heated in buffer according to a heating profile mimicking that of the surface of meat in boiling water, it appeared that cells died off much slower than predicted. It is shown that the thermal characteristics of Salmonella surviving the first 35 s of fast heating had changed. After these 35 s, remaining Salmonella survived for minutes, even at a challenge temperature of 90 °C.During heating, cell size decline was observed. A loss of intracellular water during cooking might have resulted in smaller, dehydrated cells, in cells with altered thermal resistance characteristics. This could explain why the use of standard D-and z-values did not allow the correct prediction of survival of Salmonella during fast heating in buffer, or during cooking, being attached to the surface of meat.Many factors affect the level of heat resistance of bacteria. The results of this and a former study show that attachment to meat contributes to an increased level of heat resistance of bacteria. A fast heating process further contributes to the increased level of heat resistance possibly as the result of changed thermal characteristics due to a loss of water.

Arc-Sprayed Fe-Based Coatings from Cored Wires for Wear and Corrosion Protection in Power Engineering

High wear and corrosion of parts lead to an increase in operating costs at thermal power plants. The present paper shows a possible solution to this problem through the arc spraying of protective coatings. Cored wires of the base alloying system Fe-Cr-C were used as a feedstock. Rise of wear- and heat-resistance of the coatings was achieved by additional alloying with Al, B, Ti, and Y. The wear and heat resistance of the coatings were tested via a two-body wear test accompanied by microhardness measurement and the gravimetric method, respectively. A high-temperature corrosion test was performed at 550 °C under KCl salt deposition. The porosity and adhesion strengths of the coatings were also evaluated. The microstructure was investigated with a scanning electron microscope (SEM) unit equipped with an energy dispersive X-ray (EDX) microanalyzer, and the phase composition was assessed by X-ray diffractometry. The test results showed the positive influence of additional alloying with Y on the coating properties. A comparison with commercial boiler materials showed that the coatings have the same level of heat resistance as austenite steels and are an order of magnitude higher than that of pearlite and martensite-ferrite steels. The coatings can be applied to wear- and heat-resistant applications at 20–700 °C.

Evaluation of potato clones for their adaptation to medium altitude conditions in the tropics

Potato is one of the most important crops in the world, including in the tropics. Potato requires low temperatures or cool climate for optimum tuber yield, which in the tropics, can be obtained mostly in high altitude growing areas. The limitation of land availability for potato production in highland areas of some tropical countries has steered the recent development of potato production to medium altitude areas. The objective of our study is to identify potato accessions with promising levels of heat resistance in laboratory and with good adaptation to medium altitude in the field. We used in vitro assay to screen a number of potato clones with possible resistance to heat stress on the basis literature and database of the International Potato Center, supplemented with the collection of Bogor Agricultural University. We then continued with verification of selected clones using field test in high altitude (1300 m above sea level) and medium altitude (700 m above sea level) areas. Our result showed that there is considerable variation of S. tuberosum for their adaptation to medium altitude areas in the tropics that can be exploited in breeding programs. We identified one genotype PKHT 2013-06 that was superior for its ability to produce tubers under extreme conditions. Thus, it might be very suitable to be used in a breeding program to develop tolerant varieties of potato to medium altitude areas in the tropics.

Functional Analysis of Genes Comprising the Locus of Heat Resistance in Escherichia coli.

The locus of heat resistance (LHR) is a 15- to 19-kb genomic island conferring exceptional heat resistance to organisms in the family Enterobacteriaceae, including pathogenic strains of Salmonella enterica and Escherichia coli The complement of LHR-comprising genes that is necessary for heat resistance and the stress-induced or growth-phase-induced expression of LHR-comprising genes are unknown. This study determined the contribution of the seven LHR-comprising genes yfdX1GI, yfdX2, hdeDGI, orf11, trxGI, kefB, and psiEGI by comparing the heat resistances of E. coli strains harboring plasmid-encoded derivatives of the different LHRs in these genes. (Genes carry a subscript "GI" [genomic island] if an ortholog of the same gene is present in genomes of E. coli) LHR-encoded heat shock proteins sHSP20, ClpKGI, and sHSPGI are not sufficient for the heat resistance phenotype; YfdX1, YfdX2, and HdeD are necessary to complement the LHR heat shock proteins and to impart a high level of resistance. Deletion of trxGI, kefB, and psiEGI from plasmid-encoded copies of the LHR did not significantly affect heat resistance. The effect of the growth phase and the NaCl concentration on expression from the putative LHR promoter p2 was determined by quantitative reverse transcription-PCR and by a plasmid-encoded p2:GFP promoter fusion. The expression levels of exponential- and stationary-phase E. coli cells were not significantly different, but the addition of 1% NaCl significantly increased LHR expression. Remarkably, LHR expression in E. coli was dependent on a chromosomal copy of evgA In conclusion, this study improved our understanding of the genes required for exceptional heat resistance in E. coli and factors that increase their expression in food.IMPORTANCE The locus of heat resistance (LHR) is a genomic island conferring exceptional heat resistance to several foodborne pathogens. The exceptional level of heat resistance provided by the LHR questions the control of pathogens by current food processing and preparation techniques. The function of LHR-comprising genes and their regulation, however, remain largely unknown. This study defines a core complement of LHR-encoded proteins that are necessary for heat resistance and demonstrates that regulation of the LHR in E. coli requires a chromosomal copy of the gene encoding EvgA. This study provides insight into the function of a transmissible genomic island that allows otherwise heat-sensitive enteric bacteria, including pathogens, to lead a thermoduric lifestyle and thus contributes to the detection and control of heat-resistant enteric bacteria in food.

Analysis of the Spore Membrane Proteome in Clostridium perfringens Implicates Cyanophycin in Spore Assembly.

Heat-resistant endospore formation plays an important role in Clostridium perfringens-associated foodborne illnesses. The spores allow the bacterium to survive heating during normal cooking processes, followed by germination and outgrowth of the bacterium in contaminated foods. To identify proteins associated with germination and other spore functions, a comparative spore membrane proteome analysis of dormant and germinated spores of C. perfringens strain SM101 was performed by using gel-based protein separation and liquid chromatography coupled with matrix-assisted laser desorption ionization-tandem time of flight (MALDI-TOF/TOF) mass spectrometry. A total of 494 proteins were identified, and 117 of them were predicted to be integral membrane or membrane-associated proteins. Among these membrane proteins, 16 and 26 were detected only in dormant and germinated spores, respectively. One protein that was detected only in germinated spore membranes was the enzyme cyanophycinase, a protease that cleaves the polymer cyanophycin, which is composed of l-arginine-poly(l-aspartic acid), to β-Asp-Arg. Genes encoding cyanophycinase and cyanophycin synthetase have been observed in many species of Clostridium, but their role has not been defined. To determine the function of cyanophycin in C. perfringens, a mutation was introduced into the cphA gene, encoding cyanophycin synthetase. In comparison to parent strain SM101, the spores of the mutant strain retained wild-type levels of heat resistance, but fewer spores were made, and they were smaller, suggesting that cyanophycin synthesis plays a role in spore assembly. Although cyanophycin could not be extracted from sporulating C. perfringens cells, an Escherichia coli strain expressing the cphA gene made copious amounts of cyanophycin, confirming that cphA encodes a cyanophycin synthetase. Clostridium perfringens is a common cause of food poisoning, and germination of spores after cooking is thought to play a significant role in the disease. How C. perfringens controls the germination process is still not completely understood. We characterized the proteome of the membranes from dormant and germinated spores and discovered that large-scale changes occur after germination is initiated. One of the proteins that was detected after germination was the enzyme cyanophycinase, which degrades the storage compound cyanophycin, which is found in cyanobacteria and other prokaryotes. A cyanophycin synthetase mutant was constructed and found to make spores with altered morphology but normal heat resistance, suggesting that cyanophycin plays a different role in C. perfringens than it does in cyanobacteria.