熔融沉积式燃机叶片快速熔模铸造技术研究与试验

针对某燃机叶片叶型部分形状复杂和轮廓度精度要求高的特点,提出了一种基于熔融沉积技术的燃机叶片快速熔模铸造方法,通过基于NURBS曲线的分层截面生成算法对燃机叶片STL(stereolithography)模型进行分层,提高燃机叶片模样的轮廓度精度,制订了燃机叶片快速熔模铸造工艺流程,采用三坐标测量机对燃机叶片铸件进行测量,对其两个关键截面进行型线轮廓度偏差分析与评价,结果表明:基于熔融沉积技术的快速熔模铸造燃机叶片铸件在轮廓精度方面满足要求,快速熔模铸造工艺流程合理、可行。

High quality NbTiN films fabrication and rapid thermal annealing investigation

NbTiN thin films are good candidates for applications including single-photon detector, kinetic inductance detector, hot electron bolometer, and superconducting quantum computing circuits because of their favorable characteristics,such as good superconducting properties and easy fabrication.In this work, we systematically investigated the growth of high-quality NbTiN films with different thicknesses on Si substrates by reactive DC-magnetron sputtering method.After optimizing the growth conditions, such as the gas pressure, Ar/N2 mixture ratio, and sputtering power, we obtained films with excellent superconducting properties.A high superconducting transition temperature of 15.5 K with narrow transition width of 0.03 K was obtained in a film of 300 nm thickness with surface roughness of less than 0.2 nm.In an ultra-thin film of 5 nm thick, we still obtained a transition temperature of 7.6 K.In addition, rapid thermal annealing(RTA) in atmosphere of nitrogen or nitrogen and hydrogen mixture was studied to improve the film quality.The results showed that Tc and crystal size of the NbTiN films were remarkably increased by RTA.For ultrathin films, the annealing in N2/H2 mixture had better effect than that in pure N2.The Tc of 10 nm films improved from 9.6 K to 10.3 K after RTA in N2/H2 mixture at 450℃.

Effect of SARS-CoV-2 infection on semen parameters in sperm bank volunteers with normal sperm concentration

In this study,we aimed to assess the effect of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection on semenparameters.The study comprised 110 sperm volunteers who self-reported SARS-CoV-2 infection from the Human Sperm Bank ofthe Center for Reproductive Medicine,Shandong University(Jinan,China).The volunteers had normal sperm concentration beforeinfection.Each volunteer provided semen samples before and after infection.We selected 90 days after infection as the cutoff point.Semen parameters within 90 days after infection of 109 volunteers(group A)were compared with semen parameters before infection.Moreover,semen parameters on or after 90 days after infection of 36 volunteers(group B)were compared with semen parameters beforeinfection.Furthermore,based on whether the volunteers had completed the three-dose SARS-CoV-2 vaccination booster,volunteersin group A and B were further divided into two subgroups separately.Semen parameters were compared before and after infection ineach subgroup.Our results showed that in this cohort population,the semen quality in volunteers with normal sperm concentrationsbefore infection decreased after SARS-CoV-2 infection within 90 days,while the semen quality returned to preinfection levels after 90days.The completion of a three-dose SARS-CoV-2 vaccination booster may exert a protective effect on semen quality after infection.

Decline of semen quality among Chinese sperm bank donors within 7 years （2008-2014）

Semen from 5210 sperm bank donors was analyzed and trends in semen quality were evaluated at Shandong Human Sperm Bank between 2008 and 2014. After 2-7 days of abstinence, semen samples were collected. Measurements of semen volume, sperm concentration, sperm forward motility, and total sperm count were performed. There were significant declining trends in semen volume, sperm concentration, sperm forward motility, and total sperm count. Our results indicate that the quality of semen in this cohort of sperm donors had decreased during the study period.

Comparative transcriptomic analysis reveals adriamycin-induced apoptosis via p53 signaling pathway in retinal pigment epithelial cells

Objective: This paper applied a transcriptomic approach to investigate the mechanisms of adriamycin(ADR) in treating proliferative vitreoretinopathy(PVR) using ARPE-19 cells. Methods: The growth inhibitory effects of ADR on ARPE-19 cells were assessed by sulforhodamine B(SRB) assay and propidium iodide(PI) staining using flow cytometry. The differentially expressed genes between ADR-treated ARPE-19 cells and normal ARPE-19 cells and the signaling pathways involved were investigated by microarray analysis. Mitochondrial function was detected by JC-1 staining using flow cytometry and the Bcl-2/Bax protein family. The phosphorylated histone H2 AX(γ-H2 AX), phosphorylated checkpoint kinase 1(p-CHK1), and phosphorylated checkpoint kinase 2(p-CHK2) were assessed to detect DNA damage and repair. Results: ADR could significantly inhibit ARPE-19 cell proliferation and induce caspasedependent apoptosis in vitro. In total, 4479 differentially expressed genes were found, and gene ontology items and the p53 signaling pathway were enriched. A protein–protein interaction analysis indicated that the TP53 protein molecules regulated by ADR were related to DNA damage and oxidative stress. ADR reduced mitochondrial membrane potential and the Bcl-2/Bax ratio. p53-knockdown restored the activation of c-caspase-3 activity induced by ADR by regulating Bax expression, and it inhibited ADR-induced ARPE-19 cell apoptosis. Finally, the levels of the γ-H2 AX, p-CHK1, and p-CHK2 proteins were up-regulated after ADR exposure. Conclusions: The mechanism of ARPE-19 cell death induced by ADR may be caspase-dependent apoptosis, and it may be regulated by the p53-dependent mitochondrial dysfunction, activating the p53 signaling pathway through DNA damage.

Melanization induced by Heliothis virescens ascovirus 3h promotes viral replication

Melanization is an important innate immune defense mechanism of insects,which can kill invading pathogens.Most pathogens,for their survival and reproduction,inhibit the melanization of the host.Interestingly,our results suggested that after infection with Heliothis virescens ascovirus 3h(HvAV-3h),the speed of melanization in infected Spodoptera exigiia larval hemolymph was accelerated and that the phenoloxidase(PO)activity of hemolymph in larvae infected with HvAV-3h increased significantly(1.20-fold at 96 hpi,1.52-fold at 120 hpi,1.23-fold at 144 hpi,1.12-fold at 168 hpi).The transcription level of the gene encoding S.exigua prophenoloxidase-1(SePPO-1 gene)was upregulated dramatically in the fat body during the middle stage of infection.In addition,when melanization was inhibited or promoted,the replication of HvAV-3h was inhibited or promoted,respectively.In conclusion,infection with HvAV-3h can markedly induce melanization in the middle stage of infection,and melanization is helpful for HvAV-3h viral replication.