Increased Heat Resistance Research Articles

Effect of heat adaptation and pH adjustment on the survival of spray-dried Lactobacillus paracasei SNP2

PurposeThe purpose of this paper is to study the effect of heat adaptation, pH adjustment, and the combination pretreatments to the resistance of Lactobacillus paracasei SNP2 in heat shock and spray drying.Design/methodology/approachSub-lethal and lethal temperature range of L. paracasei SNP2 was determined by enumeration of cell survival after incubation at 37-55°C for 30 min. A certain temperature from sub-lethal range was selected for heat adaptation. Heat adaptation (H), pH adjustment (pH), and combination of pretreatments (pH-H) were applied prior to heat shock and spray drying.FindingsThe selected condition for heat adaptation and heat shock is 44°C, 30 min and 55°C, 15 min, respectively, based on the sub-lethal and lethal temperature range. By heat shock, cells in the whey-sucrose medium showed cell death of 2.05 log cycles, lower than cell death in the MRS medium of 4.84 log cycles. The pretreatments showed slight increase of heat resistance in cell grown in whey sucrose. The effect of H, pH, and pH-H pretreatments highly increase heat resistance of cell grown in MRS indicated by cell death of 4.27, 3.79, and 2.43 log cycles, respectively, which is much lower than control. The pretreatments showed no significant effect to L. paracasei SNP2 survival to spray drying.Originality/valueThis is the first study of L. paracasei SNP2 resistance to heat shock and spray drying. This paper also enriches information about application of whey sucrose as a growth medium and a heating medium.

Phospholipid:Diacylglycerol Acyltransferase-Mediated Triacylglyerol Synthesis Augments Basal Thermotolerance.

High temperatures rapidly induce a genetically programmed heat-shock response (HSR) that is essential to establish short-term acquired thermotolerance. In addition, an immediate HSR-independent metabolic response is triggered, resulting in an accumulation of unsaturated triacylglycerols (TAGs) in the cytosol. The metabolic processes involved in heat-induced TAG formation in plants and their physiological significance remain to be clarified. Lipidomic analyses of Arabidopsis (Arabidopsis thaliana) seedlings indicated that during heat stress, polyunsaturated fatty acids from thylakoid galactolipids are incorporated into cytosolic TAGs. In addition, rapid conversion of plastidic monogalactosyl diacylglycerols (MGDGs) into oligogalactolipids, acylated MGDGs, and diacylglycerols (DAGs), the direct precursor of TAGs, was observed. For TAG synthesis, DAG requires a fatty acid from the acyl-CoA pool or phosphatidylcholine. Since seedlings deficient in PHOSPHOLIPID:DIACYLGLYCEROL ACYLTRANSFERASE1 (PDAT1) were unable to accumulate TAGs after heat stress, phosphatidylcholine appears to be the major fatty acid donor. Results suggest that rapid plastid lipid metabolism drives TAG accumulation during heat stress. PDAT1-mediated TAG accumulation was found to increase heat resistance, since nonacclimated pdat1 mutant seedlings were more sensitive to severe heat stress, as indicated by a more dramatic decline of the maximum efficiency of PSII and lower seedling survival compared to wild-type seedlings. In contrast, nonacclimated trigalactosyldiacylglycerol1 (tgd1) mutants overaccumulating TAGs and oligogalactolipids were more resistant to heat stress. Hence, thylakoid lipid metabolism and TAG formation increases thermotolerance in addition to the genetically encoded HSR.

SYNTHESIS AND PROPERTIES OF AROMATIC POLYESTERS WHITH CARDED FRAGMENTS

Polyethers are of great interest for various industries due to a complex of valuable properties, such as heat resistance, fire resistance, high strength, etc. Carded polymers occupy a special place among polymers with increased heat resistance, containing in the main polymer chain at least one element that is part of the lateral cyclic grouping. The presence of such fragments increases the glass transition temperature and heat resistance, which allows the copolymers to be operated at higher temperatures without changing the physico-mechanical parameters. For crystalline polymers, the presence of cardo fragments leads to better solubility in organic solvents. One of the promising ways of synthesizing heat-resistant polymeric materials is based on the use of aromatic compounds such as 3,3-bis (4'-hydroxyphenyl) phthalide, 3-chloro-3- (diphenyloxyd-4'-yl) phthalide, 3- chloro-3- (diphenylsulfide-4'-yl) phthalide, 9,9-bis (4'-hydroxyphenyl) fluorene, 9,9-bis (4'-hydroxyphenyl) anthrone-10, 2-phenyl-3,3- Bis (4'-hydroxyphenyl) phthalimidine and the like. At present, the worldwide problem of the release of toxic waste into the environment is aggravated, which causes irreversible climatic changes. To solve this problem, it was proposed to develop solid fuel cells based on polymeric proton-exchange membranes. Thus, polymer membranes must satisfy a number of requirements: to provide minimal ohmic losses, to possess considerable proton conductivity, mechanical strength, thermal stability and to have limited solubility in organic solvents. Polymer membranes with carded fragments in the main chain satisfy all the requirements. In the presented review features of synthesis and properties of copolymers on the basis of polysulfones, polyether ketones, polyetherimides with carded fragments are considered.Forcitation:Shakhmurzova K.T., Kurdanova Zh.I., Zhansitov A.A., Baiykaziev A.E., Khashirova S.Yu., Pakhomov S.I., Ligidov M.Kh.Synthesis and properties of aromatic polyesters whith carded fragments. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 6. P. 28-39.

Does increased heat resistance result in higher susceptibility to predation? A test using Drosophila melanogaster selection and hardening

Heat resistance of ectotherms can be increased both by plasticity and evolution, but these effects may have trade-offs resulting from biotic interactions. Here, we test for predation costs in Drosophila melanogaster populations with altered heat resistance produced by adult hardening and directional selection for increased heat resistance. In addition, we also tested for genetic trade-offs by testing heat resistance in lines that have evolved under increased predation risk. We show that while 35/37°C hardening increases heat resistance as expected, it does not increase predation risk from jumping spiders or mantids; in fact, there was an indication that survival may have increased under predation following a triple 37°C compared to a single 35°C hardening treatment. Flies that survived a 39°C selection cycle showed lower survival under predation, suggesting a predation cost of exposure to a more severe heat stress. There was, however, no correlated response to selection because survival did not differ between control and selected lines after selection was relaxed for one or two generations. In addition, lines selected for increased predation risk did not differ in heat resistance. Our findings suggest independent evolutionary responses to predation and heat as measured in laboratory assays, and no costs of heat hardening on susceptibility to predation.

DEVELOPMENT OF THE WORKING MODEL OF PRODUCTION REINDUSTRIALIZATION OF DIE STEEL HEAT TREATMENT

The article considers the issues related to production reindustrialization using an example of creating a working model of engineering design of the current heat treatment of stamping tool from special steel. In the process of reindustrialization it requires restoring or modernizing the production facilities, lost or outdated during deindustrialization in the postindustrial period. The development is relevant because heat treatment is integral part of the most manufacturing and conditioning processes of different instruments. With the help of national modern equipment there are opportunities for high-quality heat treatment of wide range of special steels in order to ensure the required mechanical properties of products. All major groups of die steels are considered in terms of working properties: steels with increased wear resistance, rehardened steels with high-resistance to crumbling, high impact steels, steels with medium heat resistance and higher viscosity, steels with increased heat resistance and higher viscosity, high heat resistance steels. The requirements to their properties and possible ways of obtaining these properties by different kinds of heat treatment were analyzed. Based on this analysis, by comparing of knowledge about precise use of die steels, required operation properties and possible ways of their obtaining with help of heat treatment, the modern equipment was selected to achieve the required results. There is a possibility for highquality heat treatment of wide range of die steels with Russian modern equipment in order to ensure the required mechanical characteristics of products. Currently, it is important to create modern productions that combine the colossal accumulated scientific and production experience and modern advanced technologies and equipment. It`s quite a difficult task both from a technical and economic perspective.

Heat resistance research and surface analysis of fireproof textiles with titanium silicide coating

The aim of presented work was to study two types of special fireproof textiles covered with titanium silicide coating (Fig.1). In the paper the assessment of the change in heat resistance properties and analysis structure of TiSi coated fireproof textile were carried out. The aim of the research was to study the influence of TiSi coating on the infrared radiation (thermal) resistance generated in specially designed testing stage. The radiation intensity was registered with the use of thermovision camera. The research results showed the influence of the applied coating on the heat resistance properties of the textiles.Presented research is a part of a project the aim of which is to develop a technology for manufacturing the textiles used to produce the protective clothing for emergency services and military, as well as other coated materials for a wide range of applications. The new material should be characterized with increased heat resistance coupled with protection against gas pressure impact caused e.g. by gas installation damage.

The locus of heat resistance (LHR) mediates heat resistance in Salmonella enterica, Escherichia coli and Enterobacter cloacae

Enterobacteriaceae comprise food spoilage organisms as well as food-borne pathogens including Escherichia coli. Heat resistance in E. coli was attributed to a genomic island called the locus of heat resistance (LHR). This genomic island is also present in several other genera of Enterobacteriaceae, but its function in the enteric pathogens Salmonella enterica and Enterobacter cloacae is unknown. This study aimed to determine the frequency of the LHR in food isolates of E. coli, and its influence on heat resistance in S. enterica and Enterobacter spp. Cell counts of LHR-positive strains of E. coli, S. enterica and E. cloacae were reduced by less than 1, 1, and 4 log (cfu/mL), respectively, after exposure to 60 °C for 5 min, while cell counts of LHR-negative strains of the same species were reduced by more than 7 log (cfu/mL). Introducing an exogenous copy of the LHR into heat-sensitive enteropathogenic E. coli and S. enterica increased heat resistance to a level that was comparable to LHR-positive wild type strains. Cell counts of LHR-positive S. enterica were reduced by less than 1 log(cfu/mL) after heating to 60 °C for 5 min. Survival of LHR-positive strains was improved by increasing the NaCl concentration from 0 to 4%. Cell counts of LHR-positive strains of E. coli and S. enterica were reduced by less than 2 log (cfu/g) in ground beef patties cooked to an internal core temperature of 71 °C. This study indicates that LHR-positive Enterobacteriaceae pose a risk to food safety.

Quantifying variety-specific heat resistance and the potential for adaptation to climate change.

The impact of climate change on crop yields has become widely measured; however, the linkages for winter wheat are less studied due to dramatic weather changes during the long growing season that are difficult to model. Recent research suggests significant reductions under warming. A potential adaptation strategy involves the development of heat resistant varieties by breeders, combined with alternative variety selection by producers. However, the impact of heat on specific wheat varieties remains relatively unstudied due to limited data and the complex genetic basis of heat tolerance. Here, we provide a novel econometric approach that combines field-trial data with a genetic cluster mapping to group wheat varieties and estimate a separate extreme heat impact (temperatures over 34°C) across 24 clusters spanning 197 varieties. We find a wide range of heterogeneous heat resistance and a trade-off between average yield and resistance. Results suggest that recently released varieties are less heat resistant than older varieties, a pattern that also holds for on-farm varieties. Currently released - but not yet adopted - varieties do not offer improved resistance relative to varieties currently grown on farm. Our findings suggest that warming impacts could be significantly reduced through advances in wheat breeding and/or adoption decisions by producers. However, current adaptation-through-adoption potential is limited under a 1°C warming scenario as increased heat resistance cannot be achieved without a reduction in average yields.

A mobile genetic element profoundly increases heat resistance of bacterial spores.

Bacterial endospores are among the most resilient forms of life on earth and are intrinsically resistant to extreme environments and antimicrobial treatments. Their resilience is explained by unique cellular structures formed by a complex developmental process often initiated in response to nutrient deprivation. Although the macromolecular structures of spores from different bacterial species are similar, their resistance to environmental insults differs widely. It is not known which of the factors attributed to spore resistance confer very high-level heat resistance. Here, we provide conclusive evidence that in Bacillus subtilis, this is due to the presence of a mobile genetic element (Tn1546-like) carrying five predicted operons, one of which contains genes that encode homologs of SpoVAC, SpoVAD and SpoVAEb and four other genes encoding proteins with unknown functions. This operon, named spoVA2mob, confers high-level heat resistance to spores. Deletion of spoVA2mob in a B. subtilis strain carrying Tn1546 renders heat-sensitive spores while transfer of spoVA2mob into B. subtilis 168 yields highly heat-resistant spores. On the basis of the genetic conservation of different spoVA operons among spore-forming species of Bacillaceae, we propose an evolutionary scenario for the emergence of extremely heat-resistant spores in B. subtilis, B. licheniformis and B. amyloliquefaciens. This discovery opens up avenues for improved detection and control of spore-forming bacteria able to produce highly heat-resistant spores.

Heat-resistant, extended-spectrum β-lactamase-producing Klebsiella pneumoniae in endoscope-mediated outbreak

We describe an outbreak with an extended-spectrum β-lactamase-producing Klebsiella pneumoniae strain in an intensive care unit in a secondary care hospital in Norway. The outbreak source was a fibreoptic intubation endoscope in which the outbreak strain survived despite chemothermal disinfection in a decontaminator designated for such use. The genetic marker clpK, which increases microbial heat resistance, has previously been described in K.pneumoniae outbreak strains. To investigate the role of clpK in biofilm formation and heat-shock stability in the outbreak strain. The outbreak investigation was done by review of clinical records, screening of patients and culture from intubation endoscopes and bronchoscopes. Amplified fragment length polymorphism was used to identify the outbreak strain. clpK detection was performed by polymerase chain reaction, followed by mutant construction and heat-shock assays. Five patients and one intubation endoscope contained K.pneumoniae with the same amplified fragment length polymorphism pattern. The outbreak strain contained the clpK genetic marker, which rendered the strain its increased heat resistance. The survival rate of the strain grown as biofilm following heat treatment was also strongly dependent on clpK. Although clpK has been associated with clinical isolates of K.pneumoniae in earlier outbreaks, this is the first time that a ClpK-producing strain has been isolated from an environmental outbreak source. Heat resistance of certain K.pneumoniae strains may facilitate survival in biofilms on medical equipment and hence increase the potential of those strains to persist and disperse in the hospital environment.

Influence of cyclopropane fatty acids on heat, high pressure, acid and oxidative resistance in Escherichia coli

Heat and high pressure resistant strains of Escherichia coli are a challenge to food safety. This study investigated effects of cyclopropane fatty acids (CFAs) on stress tolerance in the heat- and pressure-resistant strain E. coli AW1.7 and the sensitive strain E. coli MG1655. The role of CFAs was explored by disruption of cfa coding for CFA synthase with an in-frame, unmarked deletion method. Both wild-type strains consumed all the unsaturated fatty acids (C16:1 and C18:1) that were mostly converted to CFAs and a low proportion to saturated fatty acid (C16:0). Moreover, E. coli AW1.7 contained a higher proportion of membrane C19:0 cyclopropane fatty acid than E. coli MG1655 (P<0.05). The Δcfa mutant strains did not produce CFAs, and the corresponding substrates C16:1 and C18:1 accumulated in membrane lipids. The deletion of cfa did not alter resistance to H2O2 but increased the lethality of heat, high pressure and acid treatments in E. coli AW1.7, and E. coli MG1655. E. coli AW1.7 and its Δcfa mutant were more resistant to pressure and heat but less resistant to acid stress than E. coli MG1655. Heat resistance of wild-type strains and their Δcfa mutant was also assessed in beef patties grilled to an internal temperature of 71°C. After treatment, cell counts of wild type strains were higher than those of the Δcfa mutant strains. In conclusion, CFA synthesis in E. coli increases heat, high pressure and acid resistance, and increases heat resistance in food. This knowledge on mechanisms of stress resistance will facilitate the design of intervention methods for improved pathogen control in food production.

HEAT RESISTANCE OF TUNGSTENFREE TIC – TINI HARD ALLOYS IN DEPENDENCE ON VOLUMETRIC COMPOUND OF COMPOSITION AT HEATING UP TO HIGH TEMPERATURES

Nowadays the development of science and industrial production requires the creation of new materials, able to serve in hard conditions of external action, including high gradient temperatures, intensive impact load, as well as, in the conditions of aggressive atmosphere, hard friction regime and wear. Perspective direction, while developing such materials, is a partial and full refusal from traditional connecting hard alloys – transition material of iron group, which does not possess the required heat resistance, high-temperature strength and corrosion resistance. The usage as an alternative of a connecting phase of intermetallic compound TiNi allows increasing such characteristics. The paper is devoted to the research of the peculiarities of heat-resistant hard tungstunfree alloys of the system of TiC – TiNi in dependence on the volume content of the components in the conditions of oxidizing heating from room temperature to 900 and 1100 °С in a furnace with the heating rate of 5 °С/min. It has been established that the usage of cementing connecting phase TiNi allows increasing heat resistance and corrosion resistance of hard alloys based on TiC with intermetallics of TiNi in comparison with alloys of VK3M, VK8, T30K4 and TN – 20.

The G-protein subunits FGA2 and FGB1 play distinct roles in development and pathogenicity in the banana fungal pathogen Fusarium oxysporum f. sp. cubense

The soil-borne fungus Fusarium oxysporum f. sp. cubense causes banana (Musa spp.) vascular wilt. Here, we examine the roles of G-protein α and β subunit genes fga2 and fgb1 in F. oxysporum development and pathogenicity. Deletion of either or both genes led to increased heat resistance, lower cAMP levels, and enhanced pigmentation, whereas phenotypic defects of colony morphology and reduced conidiation were seen in Δfgb1 and Δfga2/Δfgb1 deletion strains but not in Δfga2. Conversely, Δfgb1 retained greater virulence against banana, suggesting that FGA2 regulates fungal virulence whereas FGB1 modulates both development and virulence, potentially via the cAMP-dependent protein kinase A pathway.

Plasma treatment of heat-resistant materials

Refractory lining of thermal generating units is exposed to chemical, thermal, and mechanical attacks. The degree of fracture of heat-resistant materials depends on the chemical medium composition, the process temperature and the material porosity. As is known, a shortterm exposure of the surface to low-temperature plasma (LTP) makes possible to create specific coatings that can improve the properties of workpieces. The aim of this work is to produce the protective coating on heat-resistant chamotte products using the LTP technique. Experiments have shown that plasma treatment of chamotte products modifies the surface, and a glass-ceramic coating enriched in mullite is formed providing the improvement of heat resistance. For increasing heat resistance of chamotte refractories, pastes comprising mixtures of Bacor, alumina oxide, and chamot were applied to their surfaces in different ratios. It is proved that the appropriate coating cannot be created if only one of heat-resistant components is used. The required coatings that can be used and recommended for practical applications are obtained only with the introduction of powder chamot. The paste composition of 50% chamot, 25% Bacor, and 25% alumina oxide exposed to plasma treatment, has demonstrated the most uniform surface fusion.

Investigation of using rice husk dust and ulexite in automotive brake pads

Abstract In this study, the use of rice husk (RH) dust in addition to ulexite (UX) has been investigated for estimating the effect on friction coefficient. RH includes silica which gives the pad materials a ceramic like behavior. To obtain RH, rice husk was grained after it had been dried. Different amounts of RH were included in the brake pad mix in addition to the other regular components. UX is a boron mineral which is widely used in boron glass production and in ceramic industry for increasing heat resistance and abrasion resistance. The newly formulated brake pads have been tested by the friction assessment and screening test (FAST). The friction coefficient and wear rate have been determined and investigations by scanning electron microscope (SEM) of the friction surfaces have been carried out to estimate the performance of these samples.

Zirconium dioxide thermal insulation coatings obtained by highly energized plasma spray

This paper presents the results of studying the structure, physical, and mechanical properties, and heat resistance of Ni-Co-Cr-Al-Y + ZrO2 thermal insulation coatings obtained by highly energized plasma spray on modified equipment using a PNK-50 plasmatron of an original design, involving the linear and circular injection of a powder blend. As a result of optimizing the working process, coatings with the following characteristics were produced: density ρ = 7.6 g/cm3, overall porosity P = 4.3%, open porosity Po = 1%, HV hardness = 980 kgf/mm2, and increased heat resistance. The developed coating is intended for protection against high-temperature gas corrosion and the thermal insulation of the working surfaces of parts of hot gas turbine paths.

A thermoanalytical study of curing of epoxy-amine binders modified with epoxy-containing silsesquioxane

Results of examinations of the modification of an epoxy-amine binder with MPS-E epoxy-containing silsesquioxane synthesized at the State Research Institute for Chemistry and Technology of Organo-element Compounds (SSC RF GNIIChTEOS) are under consideration. The optimal composition of the binder and the conditions used for its curing by a mixture of aliphatic and aromatic diamines were determined and it was shown that the MPS-E silsesquioxane, along with amines, participates in the curing of the ED-20 epoxy resin, thus resulting in the binder characterized by an increased heat resistance.

THE INFLUENCE OF FORMATION OF STRUCTURES AND PHASE COMPOSITION OF THE IRON CASTINGS GLASS-MOULDS ON OPERATIONAL PROPERTIES OF FINISHED PRODUCTS

The given article contains consideration of process of production and operation glass-mould. Also described the main reasons for decrease in firmness of the operation glass-moulds. The microstructure of preform is investigated at layer-by-layer and traditional hardenings of castings. Con- trol of phase composition of cast iron and formation of separate structural components in the course of hardening of castings allows to provide the increased heat resistance and heat conductivity to details of glass-moulds. In presented article described influence of each structural component on the complex of properties of details working in the conditions of cyclic thermal loadings and abrasive wear.

Interactive effects of acclimation temperature and short‐term stress exposure on resistance traits in the butterfly Bicyclus anynana

AbstractThe ability to buffer detrimental effects of environmental stress on fitness is of great ecological importance because, in nature, pronounced environmental variation may regularly induce stress. Furthermore, several stressors may interact in a synergistic manner. In the present study, plastic responses in cold, heat and starvation resistance are investigated in the tropical butterfly Bicyclus anynana Butler, 1879, using a full factorial design with two acclimation temperatures (20 and 27 °C) and four short‐term stress treatments (control, cold, heat, starvation). Warm‐acclimated butterflies are more heat‐ but less cold‐tolerant as expected. Short‐term cold and starvation exposure reduce cold and heat resistance, and short‐term heat exposure decreases cold but increases heat resistance. Starvation resistance is not affected by any of the short‐term treatments. Thus, the effects of short‐term stress exposure are either neutral or negative, except for a positive effect of heat exposure on heat resistance, indicating the negative effects of pre‐exposure to stress. Interestingly, significant interactions between acclimation temperature and short‐term stress exposure for heat and cold resistance are found, demonstrating that larger temperature differences incur more damage. Therefore, animals may not generally be able to benefit from pre‐exposure to stress (through ‘hardening’), depending on their previously experienced conditions. The complex interactions between environmental variation, stress and resistance are highlighted, warranting further investigations.

Learning Process of the Steel Use in Building Engineering Students

The present work has as main aim to make a small introduction about the types of steels, specially the ones used in the construction industry. This material is appreciated in construction due to its many advantages as strengths, resistance, adaptability and flexibility in design, durability, recyclability,…; even thou its also has week points like a low resistance to fire, weak against corrosion and a high initial cost compared with other materials. There are a high variety of ways to classify steel. So, it is very important to the building engineering students to know the classification of steel will be focused on the chemical composition of the steel, as it is the most common way of classifying it. The different types of steel will be grouped in four types: carbon steel, alloy steel, stainless steel and tool steel. In carbon steel the main alloying constituent is carbon, in a range between 0.12% and 2%. It may also content small amounts of other elements like manganese, sulphur, phosphorus and silicon. Variations in the carbon content of carbon steel can modify its mechanical properties, for example, with an increase in the carbon content from 0.01 to 1.5% in the alloy, its strength and hardness increases but still such an increase beyond 1.5% causes appreciable reduction in the ductility and malleability of the steel. Alloy steel is a term used referring to steels with other alloying elements in addition to the carbon. The content of this alloying element is between 1.0% and 50% by weight. The most common alloying elements used in this type of steel are manganese, nickel, chromium, molybdenum, vanadium, silicon, and boron; less common alloyants are aluminium, cobalt, copper, cerium, niobium, titanium, tungsten, tin, zinc, lead, and zirconium. By varying the alloy proportions steel properties such as hardenability, corrosion resistance, strength, formability, weldability or ductility can be manipulated. Stainless steel is the alloy of any type of iron that contains at least 10.50 % of chromium and no more than 1.20 % of carbon. It also may content other alloy elements such as nickel or molybdenum. These steels can be divided into four groups based on their crystalline structure. Tool steels is a variety of carbon and alloy steels, its carbon content ranges between 0.7% and 1.5%, it also contains tungsten, molybdenum, cobalt and vanadium in varying quantities to increase heat resistance and durability. They are ideal for cutting and drilling equipment, this suitability comes from their distinctive hardness, resistance to abrasion, their ability to hold a cutting edge, and/or their resistance to deformation at elevated temperatures (red-hardness).