Simulation on Effect of Divergent Angle of Submerged Entry Nozzle on Flow and Temperature Fields in Round Billet Mold in Electromagnetic Swirling Continuous Casting Process

A new process for swirling flow generation in the submerged entry nozzle （SEN） in continuous casting process of steel was proposed. A rotating electromagnetic field was set up around the SEN to induce swirling flow by Lorentz force. The flow and temperature fields in the SEN and round billet mold with electromagnetic swirling were numerically simulated and then verified by the electromagnetic swirling model experiment of low melting point alloy. The effects of divergent angle of the SEN on the flow and temperature fields in mold with electromagnetic swirling were investigated. The electromagnetic swirling flow generator （EMSFG） could effectively induce swirling flow of molten steel in the SEN, which consequently improved greatly the flow and temperature fields in the mold. Below the nozzle outlet in mold, with the increase of divergent angle, the stream of bulk flow diverged more widely, the high temperature zone shifted up, and the temperature field became more uniform. Above the nozzle outlet in mold, with 350 A electromagnetic swirling, when the divergent angle of the SEN increased, the upward flow velocity and the meniscus temperature first increased and then decreased. With a divergent angle of 60~, the upward flow velocity and meniscus temperature reaced the largest value.

Corrigendum to“Generation of Leydig-like cells:approaches,characterization,and challenges”

In the published article by Li et al.,1 an error occurred in the Acknowledgments.The funding agency should be“the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515010947)”,not“the Natural Science Foundation of Guangdong Province(No.2021A1515010947)”.The authors sincerely apologize for the error.

成年大鼠睾丸经EDs处理后再生睾丸间质细胞基因图谱的改变

成年睾丸间质细胞（ALC）是睾丸中产生雄激素的唯一内分泌细胞，只占有睾丸细胞的1％-5％。大鼠睾丸中的睾丸间质细胞被EDs去除后能够再生。本研究中，我们主要研究了大鼠睾丸经EDS处理后睾丸间质细胞再生及基因的变化图谱。EDS处理后7、21、35、90天后分析血清中睾酮、睾丸基因图谱和一些类固醇生成相关的蛋白变化情况。EDS处理后第7天睾丸中睾酮水平几乎检测不到，然后开始恢复。处理后7天，81个基因下调2倍或者更多，其中48个基因检测不到，包括类固醇合成通路中的蛋白Star、Scarbl、Cypllal、Cypl7al、Hsd3bl、CyplblICyp2al。这些基因在21天开始表达增多，到90天已经完全恢复到正常水平。89个基因上调2倍或者更高，nPkib。这些上调的基因到90天恢复正常；其中Cyp2al直到35天才开始恢复，表明这个基因只在成年睾丸间质细胞中表达，不在前体细胞中表达。qPCR，Westernblot、半定量免疫组织染色检测了随机抽取的基因和蛋白确认其变化情况。

Abnormal mold level fluctuation during slab casting of peritectic steels

Abnormal mold level fluctuation is frequently observed in high-speed casting,especially for peritectic steels,which has been shown to severely deteriorate product quality.Both an online electromagnetic sensor and an ibaAnalyzer are used to analyze the frequency and amplitude of massive mold level fluctuation data from the slab casting process of different steel grades using different casting speeds,slab widths and physical parameters of mold flux.The results show that in the slab continuous casting process of peritectic steels,the main frequency and equivalent amplitude of abnormal mold level fluctuations first increase and then decrease with increasing the carbon content.In the production of various grades of steel,the main frequency of abnormal mold level fluctuation and the equivalent amplitude increase with increasing the casting speed,while the main frequency of abnormal mold level fluctuation changes little with increasing the casting width.The main frequency of abnormal mold level fluctuation is positively related to the surface tension of the mold flux.Based on these results,a new mechanism has been presented.It is shown that the abnormal mold level fluctuation is mainly induced by shell bulging while moving through the rollers,and resonance occurs when the frequency approaches the natural frequency of the molten steel in mold,which results in a large amplitude of the abnormal mold level fluctuation.Based on this mechanism,a new equation for the resonance frequency of molten steel is proposed.The improved method based on this mechanism has proved to be effective in controlling abnormal mold fluctuations.

Generation of Leydig-like cells:approaches,characterization,and challenges

Testosterone production by Leydig cells(LCs)plays a crucial role in male reproduction.The functional degeneration of LCs can cause testosterone deficiency,ultimately resulting in primary male hypogonadism.Transplantation of exogenous LCs with the ability to produce testosterone in response to the regulation of the hypothalamus-pituitary-gonad axis could be a promising alternative option to treat male primary hypogonadism.Recent studies have shown that it is possible to generate Leydig-like cells from stem cells by various approaches.In addition,somatic cells,such as embryonic or adult fibroblasts,have also been successfully reprogrammed into Leydig-like cells.In this review,we summarized the recent advances in the generation of Leydig-like cells,with an emphasis on comparing the effectiveness and safety of different protocols used and the cells generated.By further analyzing the characteristics of Leydig-like cells generated from fibroblasts based on small signaling molecules and regulatory factors,we found that although the cells may produce testosterone,they are significantly different from real LCs.For future in vivo applications,it is important that the steroidogenic cells generated be evaluated not only for their steroidogenic functions but also for their overall cell metabolic state by proteomics or transcriptomic tools.