宽工况条件下压缩机叶根连接件损伤容限分析

某压缩机叶片采用钛合金(Ti-6Al-4V)作为叶根金属连接件材料,并且工作在宽温域和交变载荷条件下。在满足静强度和疲劳强度设计的基础上,还必须考虑材料的损伤容限问题,以合理评估其抵抗微小裂纹扩展和断裂的能力。本文在充分调研裂纹扩展速率、断裂韧性等基本材料性能的基础上,结合压缩机服役载荷谱,基于经典Paris公式计算不同工况裂纹扩展情况,并评估其服役安全性,为叶根选材提供参考依据,并给出了机组运行的建议。

A simple nanobody-based competitive ELISA to detect antibodies against African swine fever virus

African swine fever virus(ASFV) infection is a big threat to the global pig industry. Because there is no effective vaccine, rapid, low-cost, and simple diagnosis methods are necessary to detect the ASFV infection in pig herds.Nanobodies, with advantages of small molecular weight and easy genetic engineering, have been universally used as reagents for developing diagnostic kits. In this study, the recombinant ASFV-p30 was expressed and served as an antigen to immunize the Bactrian camel. Then, seven nanobodies against ASFV-p30 were screened using phage display technique. Subsequently, the seven nanobodies fused horseradish peroxidase(nanobody-HRP) were secretory expressed and one fusion protein ASFV-p30-Nb75-HRP was selected with the highest sensitivity in blocking ELISA. Using the ASFV-p30-Nb75-HRP fusion protein as a probe, a competitive ELISA(cELISA) was developed for detecting anti-ASFV antibodies in pig sera. The cut-off value of cELISA was determined to be 22.7%by testing 360 negative pig sera. The detection limit of the cELISA for positive pig sera was 1:320, and there was no cross-reaction with anti-other swine virus antibodies. The comparative assay showed that the agreement of the cELISA with a commercial ELISA kit was 100%. More importantly, the developed cELISA showed low cost and easy production as a commercial kit candidate. Collectively, a simple nanobody-based cELISA for detecting antibodies against ASFV is developed and it provides a new method for monitoring ASFV infection in the pig herds.

Comparative genomic analysis of Thermus provides insights into the evolutionary history of an incomplete denitrification pathway

Biological denitrification is a crucial process in the nitrogen biogeochemical cycle,and Thermus has been reported to be a significant heterotrophic denitrifier in terrestrial geothermal environments.However,neither the denitrification potential nor the evolutionary history of denitrification genes in the genus Thermus or phylum Deinococcota is well understood.Here,we performed a comparative analysis of 23 Thermus genomes and identified denitrification genes in 15 Thermus strains.We confirmed that Thermus harbors an incomplete denitrification pathway as none of the strains contain the nosZ gene.Ancestral character state reconstructions and phylogenetic analyses showed that narG,nirS,and norB genes were acquired by the last common ancestor of Thermales and were inherited vertically.In contrast,nirK of Thermales was acquired via two distinct horizontal gene transfers from Proteobacteria to the genus Caldithermus and from an unknown donor to the common ancestor of all known Thermus species except Thermus filiformis.This study expands our understanding of the genomic potential for incomplete denitrification in Thermus,revealing a largely vertical evolutionary history of the denitrification pathway in the Thermaceae,and supporting the important role for Thermus as an important heterotrophic denitrifier in geothermal environments.

Spatiotemporal regulation of ubiquitin-mediated protein degradation via upconversion optogenetic nanosystem

Protein degradation technology,which is one of the most direct and effective ways to regulate the life activities of cells,is expected to be applied to the treatment of various diseases.However,current protein degradation technologies such as some small-molecule degraders which are unable to achieve spatiotemporal regulation,making them difficult to transform into clinical applications.In this article,an upconversion optogenetic nanosystem was designed to attain accurate regulation of protein degradation.This system worked via two interconnected parts:1)the host cell expressed light-sensitive protein that could trigger the ubiquitinproteasome pathway upon blue-light exposure;2)the light regulated light-sensitive protein by changing light conditions to achieve regulation of protein degradation.Experimental results based on model protein(Green Fluorescent Protein,GFP)validated that this system could fulfill protein degradation both in vitro(both Hela and 293T cells)and in vivo(by upconversion optogenetic nanosystem),and further demonstrated that we could reach spatiotemporal regulation by changing the illumination time(0–25 h)and the illumination frequency(the illuminating frequency of 0–30 s every 1 min).We further took another functional protein(The Nonstructural Protein 9,NSP9)into experiment.Results confirmed that the proliferation of porcine reproductive and respiratory syndrome virus(PRRSV)was inhibited by degrading the NSP9 in this light-induced system,and PRRSV proliferation was affected by different light conditions(illumination time varies from 0–24 h).We expected this system could provide new perspectives into spatiotemporal regulation of protein degradation and help realize the clinical application transformation for treating diseases of protein degradation technology.