Heat Shock Resistance Research Articles

Sex-specific growth and lifespan effects of germline removal in the dioecious nematode Caenorhabditis remanei.

Germline regulates the expression of life-history traits and mediates the trade-off between reproduction and somatic maintenance. However, germline maintenance in itself can be costly, and the costs can vary between the sexes depending on the number of gametes produced across the lifetime. We tested this directly by germline ablation using glp-1 RNA interference (RNAi) in a dioecious nematode Caenorhabditis remanei. Germline removal strongly increased heat-shock resistance in both sexes, thus confirming the role of the germline in regulating somatic maintenance. However, germline removal resulted in increased lifespan only in males. High costs of mating strongly reduced lifespan in both sexes and obliterated the survival benefit of germline-less males even though neither sex produced any offspring. Furthermore, germline removal reduced male growth before maturation but not in adulthood, while female growth rate was reduced both before and especially after maturation. Thus, germline removal improves male lifespan without major growth costs, while germline-less females grow slower and do not live longer than reproductively functional counterparts in the absence of environmental stress. Overall, these results suggest that germline maintenance is costlier for males than for females in C. remanei.

Growth and properties of tantalum carbide coatings on graphite by TRD technique

The tantalum carbide-coated graphite material exhibits remarkable chemical stability, corrosion resistance, and heat shock resistance, enabling it to demonstrate excellent stability during the growth of wide bandgap semiconductors. Its application significantly enhances the quality of third-generation semiconductor crystals. Nevertheless, the high cost of this material hinders its widespread utilization in the field of wide bandgap semiconductors. To address this challenge, this study employs the Thermo-reaction deposition and diffusion (TRD) technique to successfully fabricate a tantalum carbide coating on the surface of graphite. Through thermodynamic analysis, this article validate the thermodynamic feasibility of preparing tantalum carbide coatings using the TRD process. To achieve a dense and uniform TaC coating on the graphite surface, we systematically investigate the effects of reducing agent content, reaction temperature, and reaction time on the microstructure of the coating. Experimental research has found that a molar ratio of B4C to Ta2O5 of 1:0.64 optimizes the coating uniformity. Deviations from this ratio, either higher or lower, can lead to coating inhomogeneity or even failure in coating formation. Additionally, this article determine that a reaction temperature range of 1200–1400 °C, coupled with a reaction time not exceeding 6 h, represents the most suitable conditions for preparing TaC coatings on the graphite surface. Finally, to evaluate the practical performance of the coated graphite, this article simulate the corrosive environment encountered during the physical vapor transport method for growing aluminum nitride single crystals. The results demonstrate a significant improvement in the corrosion resistance of the coated graphite. This enhancement is primarily attributed to the formation of a dense TaC coating on the graphite surface, which exhibits remarkable stability at elevated temperatures.

Approaches using genome-wide association studies and heat stress resistance related genes in chicken – a review

Abstract Heat stress-induced reduction in feed intake in an annoyance of the poultry industry. High environmental temperature is a serious stress affecting economic and biological efficiency of poultry production in tropical and subtropical regions countries that are expected to become more prominent with global climate change. An effective tool for improving heat tolerance can be genomic selection based on single nucleotide polymorphisms. In the past few years, new molecular tools have been developed, such as RNA-Seq, Single Nucleotide Polymorphisms (SNPs), and bioinformatics approaches such as Genome-Wide Association Study (GWAS). Based on these genetic tools, many studies have detected the main pathways involved in cellular response mechanisms. This study aims to present chicken genomic regions controlling survival against heat stress. Genetic studies conducted on experimental lines can therefore be of potential interest for marker-assisted selection in commercial lines. Also, survivability to high temperature might be due to the SNP markers that are located inside or close to the genes such as CEP78, MEF2C, VPS13A, ARRDC3, and which had relatively biological pathways in heat shock resistance.

Oxidation and Heat Shock Resistance of Plasma-Sprayed TiC-CoNi Composite Coatings at 900 °C

In this work, the TiC-reinforced CoNi alloy coatings were prepared by the plasma spraying method. Their microstructure, high-temperature oxidation, and thermal shock resistance at 900 °C were studied. The results showed that the CoNi alloy coating exhibited a single phase (c-Co-Ni-Cr-Mo). After adding Ti-graphite mixed powders, the sprayed coating exhibited TiC and TiO2 phases, besides the c-Co-Ni-Cr-Mo matrix phase. For CoNi alloy coating, the main oxidation products were Cr2O3 and CoCr2O4 (NiCr2O4). For TiC-CoNi alloy coating, the main oxidation products were the TiO2 phase, coupled with Cr2O3 and CoCr2O4 (NiCr2O4) phases. The content of oxides increased with the oxidation time. The oxidation weight gain of the TiC-CoNi composite coating was slightly higher than that of the CoNi alloy coating. The formation of TiC could improve the thermal shock resistance of the CoNi alloy coating.

Evolutionary trade-off between heat shock resistance, growth at high temperature, and virulence expression in Salmonella Typhimurium.

Bacterial pathogens such as Salmonella Typhimurium are equipped with both stress response and virulence features in order to navigate across a variety of complex inhospitable environments that range from food-processing plants up to the gastrointestinal tract of its animal host. In this context, however, it remains obscure whether and how adaptation to one environment would obstruct fitness in another. In this study, we reveal that severe heat stress counterintuitively, but invariantly, led to the selection of S. Typhimurium mutants that are compromised in the activity of the DnaJ heat shock protein. While these mutants obtained massively increased heat resistance, their virulence became greatly attenuated. Our observations, therefore, reveal a delicate balance between optimal tuning of stress response and virulence features in bacterial pathogens.

Development of heat-shock resistance in Legionella pneumophila modeled by experimental evolution.

Because it can grow in buildings with complex hot water distribution systems (HWDS), healthcare facilities recognize the waterborne bacterium Legionella pneumophila as a major nosocomial infection threat and often try to clear the systems with a pasteurization process known as superheat-and-flush. After this treatment, many facilities find that the contaminating populations slowly recover, suggesting the possibility of in situ evolution favoring increased survival in high-temperature conditions. To mimic this process in a controlled environment, an adaptive laboratory evolution model was used to select a wild-type strain of L. pneumophila for survival to transient exposures to temperatures characteristic of routine hot water use or failed pasteurization processes in HWDS. Over their evolution, these populations became insensitive to exposure to 55°C and developed the ability to survive short exposures to 59°C heat shock. Heat-adapted lineages maintained a higher expression of heat-shock genes during low-temperature incubation in freshwater, suggesting a pre-adaptation to heat stress. Although there were distinct mutation profiles in each of the heat-adapted lineages, each acquired multiple mutations in the DnaJ/DnaK/ClpB disaggregase complex, as well as mutations in chaperone htpG and protease clpX. These mutations were specific to heat-shock survival and were not seen in control lineages included in the experimental model without exposure to heat shock. This study supports in situ observations of adaptation to heat stress and demonstrates the potential of L. pneumophila to develop resistance to control measures. IMPORTANCE As a bacterium that thrives in warm water ecosystems, Legionella pneumophila is a key factor motivating regulations on hot water systems. Two major measures to control Legionella are high circulating temperatures intended to curtail growth and the use of superheat-and-flush pasteurization processes to eliminate established populations. Facilities often suffer recolonization of their hot water systems; hospitals are particularly at risk due to the severe nosocomial pneumoniae caused by Legionella. To understand these long-term survivors, we have used an adaptive laboratory evolution model to replicate this process. We find major differences between the mutational profiles of heat-adapted and heat-naïve L. pneumophila populations including mutations in major heat-shock genes like chaperones and proteases. This model demonstrates that well-validated treatment protocols are needed to clear contaminated systems and-in an analog to antibiotic resistance-the importance of complete eradication of the resident population to prevent selection for more persistent bacteria.

Bioactive Polymeric Nanoparticles of Moringa oleifera Induced Phyto-Photothermal Sensitization for the Enhanced Therapy of Retinoblastoma

Treatment of retinoblastoma is limited due to its delayed detection and inaccesbility of drugs to reach the retina crossing the blood-retinal barrier. With the advancements in nanotechnology, photothermal therapy (PTT) employing plasmonic nanomaterials and/or NIR dyes have emerged as an affordable alternative owing to the spatial control that is offered by the modality leading to localized and enhanced therapeutic efficacy with minimal invasiveness. However, the modality is limited in its clinical application owing to the increased heat shock resistance of the tumor cells in response to the heat that is generated via PTT. Hence, in this study, we explore the role of novel biomolecular fraction of Moringa oleifera (DFM) encapsulated within a polymeric nanosystem, for its anti-heat shock protein (HSP) activity. The MO extract was co-encapsulated with NIR sensitizing dye, IR820 into a biodegradable polycaprolactone (PCL) nano-delivery system (PMIR NPs). The photothermal transduction efficacy of PMIR NPs was validated in vitro against retinoblastoma cell lines. The inherent fluorescence of DFM was utilized to evaluate the cellular internalization of the PMIR NPs using fluorescence microscopy and flow cytometry. The overall oxidative protein damage and downregulation of HSP70 expression upon treatment with PMIR NPs and NIR laser irradiation was evaluated using densiometric protein analysis and Western blotting. Overall, the PMIR NPs exhibited excellent anti-cancer activity when combined with PTT with downregulated HSP70 expression against retinoblastoma cells.

Transcriptome analysis of heat resistance regulated by quorum sensing system in Glaesserella parasuis.

The ability of bacteria to resist heat shock allows them to adapt to different environments. In addition, heat shock resistance is known for their virulence. Our previous study showed that the AI-2/luxS quorum sensing system affects the growth characteristics, biofilm formation, and virulence of Glaesserella parasuis. The resistance of quorum sensing system deficient G. parasuis to heat shock was obviously weaker than that of wild type strain. However, the regulatory mechanism of this phenotype remains unclear. To illustrate the regulatory mechanism by which the quorum sensing system provides resistance to heat shock, the transcriptomes of wild type (GPS2), ΔluxS, and luxS complemented (C-luxS) strains were analyzed. Four hundred forty-four differentially expressed genes were identified in quorum sensing system deficient G. parasuis, which participated in multiple regulatory pathways. Furthermore, we found that G. parasuis regulates the expression of rseA, rpoE, rseB, degS, clpP, and htrA genes to resist heat shock via the quorum sensing system. We further confirmed that rseA and rpoE genes exerted an opposite regulatory effect on heat shock resistance. In conclusion, the findings of this study provide a novel insight into how the quorum sensing system affects the transcriptome of G. parasuis and regulates its heat shock resistance property.

Improved plant heat shock resistance is introduced differently by heat and insect infestation: the role of volatile emission traits

Heat stress is one of the most important abiotic stresses confronted by plants under global climate change. Plant exposure to abiotic or biotic stress can improve its tolerance to subsequent severe episodes of the same or different stress (stress priming), but so far there is limited comparative information about how pre-exposures to different abiotic and biotic elicitors alter plant resistance to severe heat stress. We exposed the perennial herb Melilotus albus Medik., a species rich in secondary metabolites, to moderate heat stress (35°C) and greenhouse whitefly (Trialeurodes vaporariorum West.) infestation to comparatively determine whether both pre-treatments could enhance plant tolerance to the subsequent heat shock (45°C) stress. Plant physiological responses to stress were characterized by photosynthetic traits and volatile organic compound emissions through 72h recovery. Heat shock treatment reduced net assimilation rate (A) and stomatal conductance in all plants, but heat-primed plants had significantly faster rates of recovery of A than other plants. By the end of the recovery period, A in none of the three heat shock-stressed groups recovered to the control level, but in whitefly-infested plants it reached the pre-heat shock level. In heat-primed plants, the heat shock treatment was associated with a fast rise of monoterpene emissions, and in whitefly-infested plants with benzenoid emissions and an increase in total phenolic content.

Heat Shock Transcription Factor CgHSF1 Is Required for Melanin Biosynthesis, Appressorium Formation, and Pathogenicity in Colletotrichum gloeosporioides.

Heat shock transcription factors (HSFs) are a family of transcription regulators. Although HSFs’ functions in controlling the transcription of the molecular chaperone heat shock proteins and resistance to stresses are well established, their effects on the pathogenicity of plant pathogenic fungi remain unknown. In this study, we analyze the role of CgHSF1 in the pathogenicity of Colletotrichum gloeosporioides and investigate the underlying mechanism. Failure to generate the Cghsf1 knock-out mutant suggested that the gene is essential for the viability of the fungus. Then, genetic depletion of the Cghsf1 was achieved by inserting the repressive promoter of nitrite reductase gene (PniiA) before its coding sequence. The mutant showed significantly decrease in the pathogenicity repression of appressorium formation, and severe defects in melanin biosynthesis. Moreover, four melanin synthetic genes were identified as direct targets of CgHSF1. Taken together, this work highlights the role of CgHSF1 in fungal pathogenicity via the transcriptional activation of melanin biosynthesis. Our study extends the understanding of fungal HSF1 proteins, especially their involvement in pathogenicity.

Influence of Y2O3 on densification, flexural strength and heat shock resistance of cordierite-based composite ceramics

In order to fabricate a heat transfer ceramic-based pipeline for concentrated solar power, rare earth Y 2 O 3 was utilized as a modifying agent to improve the physico-chemistry properties of the cordierite-based composite ceramics. The influences of the sintering temperature and Y 2 O 3 additive on the densification, flexural strength, and thermostability were investigated. The research results indicate that the densification degree of the composite ceramics gradually increases with elevated temperature, and the initial sintering temperature decreases with the addition of Y 2 O 3 . In addition, the flexural strength and heat shock resistance of the ceramic materials were improved with the addition of Y 2 O 3 . In particular, a sample containing 7 wt% Y 2 O 3 (sample E4) sintered at 1360 °C showed the best properties with a relative density of 92.49%, a flexural strength of 126.81 MPa, and strength loss rate of -7.74% after 30 heat shock cycles. X-ray diffraction and scanning electron microscopy analysis showed that parts of Y 3+ ions dissolving into high-temperature liquid phases could reduce liquid viscosity to accelerate grain crystallization and pore elimination. The second phase of yttrium silicate properly impeded the generation of β-spodumene with lower strength during the heat shock process. Overall, a cordierite-based composite ceramic with low porosity was obtained with high mechanical strength and heat shock resistance and can be regarded as a highly potential material for solar heat transfer pipelines.

Preliminary studies on the main characteristics and transient heat shock performances of detonation sprayed tungsten coatings on 316 L steel substrates

Detonation spraying (DS) method was used to deposit tungsten coatings on 316 L steel substrates for the potential usage of the first wall of blanket in nuclear fusion devices. The main characteristics and anti-transient heat shock performances of the DS-W coatings were studied and compared with that of the atmospheric plasma sprayed tungsten (APS-W) coatings. The results showed that the DS-W coating had a very dense structure with its porosity of about 0.97%. The oxygen content of the DS-W coating that roughly detected with an energy dispersive spectrometer was much lower than that of the APS-W coating and the initial tungsten powders. It was considered that this result should be due to the unexpectedly introduced W2C during the DS process. These W2C would act as deoxidation agent and decrease the oxygen content in the coating. The microhardness of the DS-W coatings was much higher than that of the APS-W coatings and the pure tungsten bulk. It was analyzed that the dense structure, the reinforcement by W2C and the fine-grained strengthening effect during the DS process were responsible for this result. Furthermore, the DS-W/steel specimens exhibited excellent bonding strength and transient heat shock resistance. After having been tested under 3.5 MJ/m2 of transient heat loads, the DS-W/steel sample was still on a good status without obvious damages. Besides, it was believed that the overall performance of the DS-W coatings should be further improved through appropriate post-processing methods. As a conclusion, the DS-W coating demonstrated outstanding properties and its great potential for the application in plasma-facing materials.

Increased fidelity of protein synthesis extends lifespan

SummaryLoss of proteostasis is a fundamental process driving aging. Proteostasis is affected by the accuracy of translation, yet the physiological consequence of having fewer protein synthesis errors during multi-cellular organismal aging is poorly understood. Our phylogenetic analysis of RPS23, a key protein in the ribosomal decoding center, uncovered a lysine residue almost universally conserved across all domains of life, which is replaced by an arginine in a small number of hyperthermophilic archaea. When introduced into eukaryotic RPS23 homologs, this mutation leads to accurate translation, as well as heat shock resistance and longer life, in yeast, worms, and flies. Furthermore, we show that anti-aging drugs such as rapamycin, Torin1, and trametinib reduce translation errors, and that rapamycin extends further organismal longevity in RPS23 hyperaccuracy mutants. This implies a unified mode of action for diverse pharmacological anti-aging therapies. These findings pave the way for identifying novel translation accuracy interventions to improve aging.

Evolution of sex-specific heat stress tolerance and larval Hsp70 expression in populations of Drosophila melanogaster adapted to larval crowding.

The ability to tolerate temperature stress is an important component of adult fitness. In holometabolous insects like Drosophila melanogaster, adult stress resistance can be affected by growth conditions experienced during the larval stages. Although evolution under crowded larval conditions is known to lead to the correlated evolution of many adult traits, its consequences on adult heat stress tolerance have not been investigated. Therefore, in the present study, we assessed the adult heat stress tolerance in populations of D. melanogaster adapted to a stressful larval crowding environment. We used replicate populations ofD. melanogaster, selected for adaptation to larval crowding stress (MCUs), for more than 230 generations, and their respective controls (MBs). Larvae from selected and control populations were grown under crowded and uncrowded conditions, and their adult heat shock resistance at two different temperatures was measured. Further, we compared Hsp70 expression in crowded and uncrowded larvae of both populations and also measured the Hsp70 expression after a mild heat treatment in adults of selected and control populations. Our results showed that adaptation to larval crowding leads to the evolution of Hsp70 gene expression in larval stages and improves adult heat stress tolerance ability in males, but not in females.

Molecular cloning and expression dynamics of UNC-45B upon heat shock in the muscle of yellowtail

As a myosin chaperone, uncoordinated-45B (UNC-45B) is expressed specifically in striated muscle tissues. It has been proved that overheat shock will lead to myosin denaturation, and that UNC-45B is involved in myosin assembly. Yellowtail was chosen for this study, as an important economic aquaculture fish worldwide. To establish the heat shock response of UNC-45B in yellowtail, cDNA cloning and expression analysis were carried out. The cDNA of yellowtail unc-45b was successfully cloned, and consisted of 3051 bp encoding 930 amino acid residues (ORF 2793 bp). Based on the sequence of yellowtail unc-45b, we designed original primers and an anti-peptide antibody for our study. Yellowtail were then exposed to short-term or long-term heat shock, and UNC-45B expression levels were determined by qPCR and western blot analysis. For short-term heat shock exposure, the fish were kept in water tanks at 25 °C (control group) and 30 °C (heat shock group) for up to 30 h. The mRNA and protein expression levels of UNC-45B increased markedly after 8 h and 24 h, respectively. To investigate the effects of long-term heat shock exposure, cultured yellowtail were sampled in summer and winter at sea surface temperatures of 30 °C and 14 °C. The expression of UNC-45B in both mRNA and protein levels was significantly higher in summer than in winter. Our results show that the increase in UNC-45B expression levels can reflect heat shock response sensitively, and it is suggested that UNC-45B can repair the denatured myosin during heat shock exposure in yellowtail. Moreover, we successfully detected the protein expression of UNC-45B in aquaculture fish species in native conditions by using western blot analysis for the first time. Therefore, we assume that UNC-45B can be regarded as a biomarker to predict heat shock resistance level. This would help in aquaculture production, in the selection of juveniles able to endure heat shock.

(Invited) Advances in Ag Sinter Joining for WBG Power Device Assembly and High Temperature Reliability

SiC and GaN, wide bandgap semiconductors (WBGs), providing great benefits such as excellent energy saving, high power density, size reduction of power module, and long-life time, have been attracting many researchers for decades. Actually, there are several new products in the world market. At this moment, one of the technology demands for expanding the market of SiC/GaN is on power packaging technology, which can open these great functions. The increasing power density leads to high operation temperature beyond 200 °C at semiconductor junctions. Not only SiC/GaN devices themselves, insulating ceramic substrates such DBC and DBA must possess good heat-conductivity, heat-resistance and heat-shock resistance. Temperature swing range in operation will be from -50 °C to 250 °C, which is quite severe for the conventional packaging materials including not only insulating substrates, but also solders, wiring, molding compounds, and others. In our group, new assembly materials have been demonstrated and new design rules of die-attach and insulating substrates have been explored to realize reliable SiC/GaN power devices.Sinter joining technology is one of the most promising bonding methods for realizing both high performance and high reliability for WBG devices. The author has developed Ag micron-particles sinter joining with a hybrid of Ag micron/submicron size particles providing excellent heat-resistance beyond 200 °C without any assisting pressure. Ag reacts with oxygen in air resulting in low temperature sintering around 200 °C. The microporous joining structure provides high strength as well as excellent heat/electric conductivity. The die-attached devices are stable even up to 250 °C in thermal shock and in power cycling. For joining Ag sinter materials to various metallization faces such as Au, Ni, Cu or Al, has another critical factor to influence device performance. Ag sinter paste to Ag metallization face is the most recommended one. However, from the various requirements in the market, Ag sinter joining must be also applicable to these dissimilar surfaces. The latest sinter paste enables joining Ag sinter paste even to Al as shown in Fig. 1, which has been recognized as one of the most difficult combination. In this example, the bonding strength reached 35 MPa when bonded at 200 °C.Metal bonded ceramic substrates are the other key materials for WBG power modules. DBAs of AIN, Si3N4 and Al2O3 can survive even in severe thermal shock test between -50 °C to 250 °C. However, significant deformation of metal plates bonded on rigid ceramic insulators results in serious degradation of the WBG assembly. It was found that the properties of surface plating have a key to suppress this surface deformation.Operation monitoring in real service environment will be one of the useful technology for power devices. A nondestructive inspection method by using AE monitoring has been proposed to understand the degradation of module during thermal cycling. During power cycling, abrupt stepwise increases in AE occur showing crack extension in a die-attach layer. Figure 1

Purification of Yeast Spores to Investigate Their Dynamics of Activation.

Germination is an important developmental process that supports resumption of growth in dormant spores. The study of the mechanisms underlying germination requires a pure spore population devoid of other cell types. This article describes the sporulation of wild Saccharomyces cerevisiae and Saccharomyces paradoxus strains, and the isolation and purification of ascospores. We also describe a method to synchronously induce germination in a spore population as well as to measure spore activation. This procedure can be applied, for example, to the study of environmental conditions that trigger germination. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Sporulation Basic Protocol 2: Spore purification Basic Protocol 3: Germination induction Support Protocol 1: Flow cytometry analysis Support Protocol 2: Heat-shock resistance measurement.

Wear and heat shock resistance of Ni-WC coating on mould copper plate fabricated by laser

A Ni-WC coating was fabricated successively on a copper substrate by laser. The microstructure, hardness and wear resistance were investigated. The thickness of Ni-WC coating was 0.65mm and average hardness of strengthening layer was 667HV0.1, which was approximately 7.8 times higher than the hardness of copper substrate. The wear volume of Ni-WC coating was only 0.014mm3, which was only 1.02% wear volume of copper substrate. The decrease in wear volume was mainly due to presence of reinforced phases, such as γ-Ni, Cr0.19Fe0.7Ni0.11, M7C3, M23C6 and WC. In addition, there was no coating peeled off after 100 times trials of heat shock resistance experiment at 800℃. The experimental results show that this Ni-WC coating has a good metallurgical bonding strength and hardness, and it also has good wear resistance and high temperature property, which is helpful to improve the service life of mould copper plate.

LAM Genes Contribute to Environmental Stress Tolerance but Sensibilize Yeast Cells to Azoles.

Lam proteins transport sterols between the membranes of different cellular compartments. In Saccharomyces cerevisiae, the LAM gene family consists of three pairs of paralogs. Because the function of paralogous genes can be redundant, the phenotypes of only a small number of LAM gene deletions have been reported; thus, the role of these genes in yeast physiology is still unclear. Here, we surveyed the phenotypes of double and quadruple deletants of paralogous LAM2(YSP2)/LAM4 and LAM1(YSP1)/LAM3(SIP3) genes that encode proteins localized in the junctions of the plasma membrane and endoplasmic reticulum. The quadruple deletant showed increased sterol content and a strong decrease in ethanol, heat shock and high osmolarity resistance. Surprisingly, the quadruple deletant and LAM2/LAM4 double deletion strain showed increased tolerance to the azole antifungals clotrimazole and miconazole. This effect was not associated with an increased rate of ABC-transporter substrate efflux. Possibly, increased sterol pool in the LAM deletion strains postpones the effect of azoles on cell growth. Alternatively, LAM deletions might alleviate the toxic effect of sterols as Lam proteins can transport toxic sterol biosynthesis intermediates into membrane compartments that are sensitive to these compounds. Our findings reveal novel biological roles of LAM genes in stress tolerance and suggest that mutations in these genes may confer upregulation of a mechanism that provides resistance to azole antifungals in pathogenic fungi.

Microstructure and Properties of Ni-Co Composite Cladding Coating on Mould Copper Plate.

In this study, a Ni–Co composite coating was fabricated successively on a copper substrate by laser, and the microstructure and properties of the composite coating were studied. Our results show that the elements from Ni and Co alloy powder were uniformly distributed in the binding region, which obtained a good metallurgical bonding with the substrate. The microhardness of Co-based coatings was 646 HV0.1, which was approximately 7.6 times greater than the hardness of Cu substrate. The Ni-based coating hardness was a little lower than that of the Co-based coating, which was approximately 7.0 times higher than the hardness of Cu substrate. The Co-based coating was comprised of reinforced phases, such as Co, Ni–Cr–Co–Mo, M7C3 and {Fe, Ni}. The wear volume of Co-based coatings was approximately 0.164 mm3 after the sliding wear test at 60 min, which was only 4% of the substrate’s wear volume. Meanwhile, the heat shock resistance experiment was carried out at 800 °C for 75 times before the Ni–Co composite coating was peeled off. It was shown that this Ni–Co composite coating had good wear resistance and high temperature properties, which is helpful to improve the service life of a mould copper plate. It not only saves the economic cost of steel plants, but also improves the quality of slabs and products.