超声振动对2195铝锂合金搅拌摩擦焊接头显微组织与力学性能的影响

采用新型超声振动强化搅拌摩擦焊对第三代2195-T6铝锂合金进行焊接,研究超声振动对接头显微组织与力学性能的影响。研究表明,超声振动强化搅拌摩擦焊能够增强塑性材料流动,进而抑制焊接缺陷,提高无缺陷接头的临界焊接速度。在保证接头抗拉强度达到母材75%的条件下,超声振动强化搅拌摩擦焊的焊接速度和效率均高于常规搅拌摩擦焊。施加超声振动能够大幅提升较高焊接速度条件下的接头力学性能。超声振动强化搅拌摩擦焊接头的极限抗拉强度为449.5 MPa,达到母材的83.1%。超声振动强化搅拌摩擦焊接能够在保证接头质量的前提下提升临界焊接速度和焊接效率。

立方金属材料衍射线形分析改良方法的应变各向异性模型

为了探讨引起应变各向异性的本质原因,系统分析采用不同弹性模型计算的立方金属材料(铜、5383铝合金、面心立方奥氏体钢和体心立方铁素体钢)的各向异性程度。模型和实验结果均显示弹性模量的倒数(1/Ehkl)与取向参数(Γ)之间的关系曲线具有稳定的交叉点,并进一步验证基于准弹塑性模型的线形宽化分析方法在冷变形样品中修正应变各向异性的有效性。与此同时,通过对基于位错模型的线形分析方法中最重要的平均衍射对比因子参数(Chkl)分析发现,其数值与弹性常数密切相关,并观察到Chkl与Γ曲线存在有趣的交叉点。因此,在传统衍射线形分析过程中,其输入的Ch00值因给定弹性常数的不同而呈现较大波动,进而影响最终分析结果。相应地,本文提出一种改良的线形分析方法,即采用优化的稳定交叉点作为初始输入值,获得更可靠性的分析结果。

SOD2 Alleviates Hearing Loss Induced by Noise and Kanamycin in Mitochondrial DNA4834-deficient Rats by Regulating PI3K/MAPK Signaling

Superoxide dismutase 2(SOD2)-mediated gene therapy has significant protective effects against kanamycin-induced hearing loss and hair cell loss in the inner ear,but the underlying mechanisms are still unclear.Herein,an in vivo aging model of mitochondrial DNA(mtDNA)4834 deletion mutation was established using D-galactose,and the effects of noise or kanamycin on inner ear injury was investigated.Rats subjected to mtDNA4834 mutation via D-galactose administration showed hearing loss characterized by the disruption of inner ear structure(abnormal cell morphology,hair cell lysis,and the absence of the organ of Corti),increased SOD2 promoter methylation,and an increase in the degree of apoptosis.Exposure to noise or kanamycin further contributed to the effects of D-galactose.SOD2 overexpression induced by viral injection accordingly counteracted the effects of noise and kanamycin and ameliorated the symptoms of hearing loss,suggesting the critical involvement of SOD2 in preventing deafness and hearing-related conditions.The PI3K and MAPK signaling pathways were also regulated by noise/kanamycin exposure and/or SOD2 overexpression,indicating that they may be involved in the therapeutic effect of SOD2 against age-related hearing loss.

Genotyping of strains of Yersinia pestis from Marmota baibacina-Spermophilus undulates Plague Focus of Tianshan Mountains in China

The airn of this study is to carry out genotyping of 61 Y.pestis strains isolated from Marmota baibacina-Spermophilus undulates Plague Focus of Tianshan Mountains in China. Primer pairs targeting the 22 DFRs were designed for detecting the genotypes of 61 strains. As a result, 61 strains of Y.pestis were divided into four genotypes 1, 2, 3, and 4. Genotypes 1, 2 and 3 were found from west part in Northern Tianshan Mountains Plague Focus, but type 1 was only from Nileke county. The type of strains from Aheqi was different from those of Atushi counties in Southern Tianshan Mountains and similar to strains in Northern Tianshan Mountains Plague Focus. The type 4 distributed over Atushi county, which was identical with that of strains from Marmota caudae Plague Focus of the Pamiri Plateau. It is concluded that geonotyping is identical with ecotyping made by Shuli Ji. Tianshan Mountains Plague Focus and Marmota caudae Plague Focus of the Pamiri Plateau have a cross spreading profile.

Can Digital Transformation Definitely Improve Firms'Markups?

In this paper,digital transformation is included in the heterogeneity model of firms.Based on a general equilibrium analysis,we find that under the effect of diminishing marginal productivity,digital transformation does not always have a positive impact on firms'markups,but has an"inverted U-shaped"nonlinear influence,which first promotes and then inhibits markups.Firm innovation and firm productivity are the key micro-mechanisms for the above effects to play a role.Based on the analysis of typical facts and empirical data of listed companies,the measurement test yields the following results.First,digital transformation can significantly improve firms'markups when it is below a specific threshold value,but it will have a negative impact when it exceeds this value.That is,there is an"inverted U-shaped"nonlinear relationship between digital transformation and firms'markups.Second,the heterogeneity analysis shows that digital transformation has a greater effect on the markups of state-owned firms,export firms and technology-intensive firms than on the markups of other firms.Third,digital transformation has an impact on firms'markups through two key mechanisms:firm innovation ability and production eficiency.The quantitative empirical results confirm the correctness of the theoretical expectations.Therefore,firms need to grasp the strategic opportunities brought by the progress of digital technology and accelerate the process of promoting the digital transformation.Firms should make proper choices in the selection and arrangement of key areas,as well as avoid possible problems such as"too much".In this way,we can better consolidate the micro foundation of China's high-quality economic development.

Effect of rare earth content on microstructure and corrosion resistance of hot-dip Zn-5Al alloy coated steel wire for bridge cables

The effects of the content of rare earth elements on the microstructure and properties of hot-dip Zn-5 Al alloy steel wire for bridge cables were investigated.The microstructure of the hot-dip coating was analyzed using an optical microscope and a scanning electron microscope equipped with an energy-dispersive spectrometer.The bonding force between the hot-dip coating and steel wire was determined by the winding test.The corrosion resistance of the steel wire hot-dip coating was tested by the electrochemical workstation.The hot-dip Zn-5A1 alloy coating has a corrosion-resistant structure composed of a zinc-rich phase and an aluminum-rich phase.Due to the enhanced bonding force,the micro structure of the hot-dip coating of the Zn-5A1 alloy with rare earth elements is more compact and uniform than that without rare earth elements.The addition of rare earth elements improves the corrosion resistance of Zn-5A1 alloy coated steel wire.Due to the rare earth segregation,which prevents the corrosion of the grain boundary and enhances the anti-intergranular corrosion performance,steel wire exhibits the optimum corrosion resistance when the content of rare earth elements is 0.08 wt.%.

基于深度集成学习的社交网络异常数据挖掘算法

针对当前社交网络异常数据挖掘算法设计过程中未提取社交网络数据特征,导致异常数据检测率低、检测运行时间长的问题,提出一种基于深度集成学习的社交网络异常数据挖掘算法。该算法首先挖掘社交网络数据,依据数据挖掘结果提取社交网络数据特征;然后利用提取到的数据特征构建深度集成学习模型,通过该模型对异常数据进行预测,以此获得社交网络异常数据,实现社交网络异常数据挖掘。实验结果表明:通过对该算法进行异常数据检测率测试和异常数据检测运行时间测试,验证了该算法的准确性高、有效性强、实际应用效果好。

Complications and management of penile augmentation with hyaluronic acid injection

Hyaluronic acid injection is becoming a popular way for penile augmentation.However,only few studies and follow-ups have investigated the various complications of hyaluronic acid injection and their corresponding management.In this study,a total of 230 patients who had penile augmentation with hyaluronic acid injection from January 2018 to December 2019 were examined on follow-up for penile girth,complications,and their corresponding management.At 1-month,3-month,and 6-month postoperative follow-ups,the penile circumference had increased by 2.66±1.24 cm,2.28±1.02 cm,and 1.80±0.83 cm,respectively.During the entire 6-month follow-up,4.3%had complications such as subcutaneous bleeding,subcutaneous nodules,and infection.There were no systemic or local allergic reactions among all the patients.All complications were treated accordingly,and no further deterioration or severe sequelae were observed.Although complications of hyaluronic acid injections are mild and rare,these may affect the patient's satisfaction postoperatively.Preoperative redundant prepuce may increase the incidence of penile edema or postoperative gel migration.Standardization of the surgery protocol and elucidation of the effects of other injection parameters are still lacking.Nevertheless,it still highlights the importance of preoperative preparation and surgical technique.