Effect of intermetallics on susceptibility of Mg alloy welds to liquation cracking

ABSTRACT

The circular-patch welding test was used to study the liquation and liquation cracking of AZ-series Mg alloys. A heat treatment was carried out on the as-received AZ91 alloy to dissolve the γ(Mg₁₇Al₁₂) particles before welding. The circular-patch welding test was then conducted on the heat-treated, as-received AZ91 alloy using AZ61 and AZ91 filler wires. The results showed that the susceptibility of AZ91 alloy to liquation and liquation cracking was significantly reduced by the dissolution of massive γ(Mg₁₇Al₁₂) particles via a heat treatment before welding as the liquation mechanism was changed. Both constitutional liquation and incipient melting occurred in the partially melted zone of the as-received AZ91 welds, while only incipient melting occurred in the heat-treated AZ91 welds.     

The Gut Microbiota: A Potential Gateway to Improved Health Outcomes in Breast Cancer Treatment and Survivorship

Breast cancer is the most frequently diagnosed cancer in women worldwide. The disease and its treatments exert profound effects on an individual’s physical and mental health. There are many factors that impact an individual’s risk of developing breast cancer, their response to treatments, and their risk of recurrence. The community of microorganisms inhabiting the gastrointestinal tract, the gut microbiota, affects human health through metabolic, neural, and endocrine signaling, and immune activity. It is through these mechanisms that the gut microbiota appears to influence breast cancer risk, response to treatment, and recurrence. A disrupted gut microbiota or state of ‘dysbiosis’ can contribute to a biological environment associated with higher risk for cancer development as well as contribute to negative treatment side-effects. Many cancer treatments have been shown to shift the gut microbiota toward dysbiosis; however, the microbiota can also be positively manipulated through diet, prebiotic and probiotic supplementation, and exercise. The objective of this review is to provide an overview of the current understanding of the relationship between the gut microbiota and breast cancer and to highlight potential strategies for modulation of the gut microbiota that could lead to improved clinical outcomes and overall health in this population.     

复杂岩基地质海上风电高桩承台基础关键技术研究及应用

本文针对福建海域复杂的地质特点,以岩基海床高桩承台基础为研究对象,对基础的承台选型、承台结构设计进行分析,结合基础的载荷计算、结构的内力建模、基础的实际监测数据,研究表明高桩中承台嵌岩基础满足设计规范要求。同时,以嵌岩基础施工为例,从桩基施工、承台施工2方面详细阐述了基础施工工艺,实践表明,采用打桩架固定式沉桩、整体式嵌岩平台、装配式预制钢套箱工艺可显著提高施工效率,满足工程建设要求。该高桩承台基础设计和施工方案可为东南沿海类似工程提供参考。     

Research of laser remelting on the thermal-mechanical behaviors and heat treatment of yttria-stabilized zirconia coatings

In this study, the thermal and mechanical behaviors were investigated by simulating laser remelting of atmospheric plasma-sprayed yttria-stabilized zirconia coatings, and the molten depth and regions of stress concentration were compared between simulation and experiment. The heat  treatment process of the remelted coating was also simulated. The crack formation mechanism in the YSZ coating remelted by laser and the heat-treatment effect on residual stress were investigated. Results showed that the simulated results were consistent with the experimental measurements, and the residual thermal stress was the main cause of cracks formation. The coating remelted by a laser power of 1500 W and a scanning rate of 9 mm/s possessed less residual concentrated stress and segmented cracks. Heat treatment released concentrated stress, which was still accurate for the ceramic coating. If the coatings were slowly heated to demonstrate heat treatment after laser remelting, the cracks in the remelted layer decreased correspondingly.     

Translational Read-Through Therapy of RPGR Nonsense Mutations

X-chromosomal retinitis pigmentosa (RP) frequently is caused by mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene. We evaluated the potential of PTC124 (Ataluren, Translama^TM) treatment to promote ribosomal read-through of premature termination codons (PTC) in RPGR. Expression constructs in HEK293T cells showed that the efficacy of read-through reagents is higher for UGA than UAA PTCs. We identified the novel hemizygous nonsense mutation c.1154T > A, p.Leu385* ({"type":"entrez-nucleotide","attrs":{"text":"NM_000328.3","term_id":"1677500221"}}NM_000328.3) causing a UAA PTC in RPGR and generated patient-derived fibroblasts. Immunocytochemistry of serum-starved control fibroblasts showed the RPGR protein in a dot-like expression pattern along the primary cilium. In contrast, RPGR was no longer detectable at the primary cilium in patient-derived cells. Applying PTC124 restored RPGR at the cilium in approximately 8% of patient-derived cells. RT-PCR and Western blot assays verified the pathogenic mechanisms underlying the nonsense variant. Immunofluorescence stainings confirmed the successful PTC124 treatment. Our results showed for the first time that PTC124 induces read-through of PTCs in RPGR and restores the localization of the RPGR protein at the primary cilium in patient-derived cells. These results may provide a promising new treatment option for patients suffering from nonsense mutations in RPGR or other genetic diseases.     

基于单神经元PID的真空炉自适应温度控制

根据真空热处理系统的特点,将单神经元PID控制算法应用到真空热处理系统的温度控制上。根据神经网络的非线性逼近能力和自学习自适应的特点,将单神经元网络与PID控制结合实现对真空炉温度的控制,以达到提高真空炉温度控制品质的目的。并通过计算机仿真软件进行仿真试验,仿真结果表明单神经元PID控制系统可以对控制参数自整定,其对温度控制更加稳健,具有更强的抗干扰能力和鲁棒性。经过搭建真空炉温度控制系统试验平台验证后发现,应用单神经元PID控制的真空炉系统的温升过程表现出了良好的稳定性,但是温度控制的响应速度和保温的精度略有下降。要想进一步提高温控品质,需要就单神经元PID控制方法在响应速度和控制精度上做进一步改进。     

热处理工艺对15CrMoR钢带状组织和冲击性能的影响

利用光学显微镜、扫描电镜和冲击试验机等仪器研究了15CrMoR钢中带状组织在热处理过程中的演变及其对冲击性能的影响。结果表明:奥氏体化后缓冷会出现铁素体-珠光体带状组织, 快冷则可以抑制带状组织的出现,但快冷会导致粒状贝氏体等非平衡组织形成。粒状贝氏体组织中的贝氏体铁素体基体和马氏体-奥氏体岛在回火过程中逐渐沿Cr、Mo等碳化物形成元素偏聚的区域分解出碳化物,形成富碳化物带,降低钢的横向冲击性能。15CrMoR钢加热到1100 ℃并保温7 h后可消除带状组织,改善钢的横向冲击性能。     

脉冲电磁处理参数对YT15硬质合金服役寿命的影响

采用COMSOL Multiphysics有限元分析软件对脉冲电磁处理设备进行仿真建模,利用正交试验的方法研究了磁通密度、磁脉冲个数、脉冲电压、电脉冲组数对YT15硬质合金刀具服役寿命的影响规律。通过极差分析得到了各因素的影响主次关系以及最佳脉冲电磁处理参数,并分析了切削过程的主切削力及磨损量变化,结果表明:脉冲电磁处理可使YT15硬质合金刀具服役寿命增长57.2%;最佳的处理参数组合为磁通密度2T,磁脉冲个数10,脉冲电压0.8V,电脉冲组数20;磁通密度和磁脉冲个数对其寿命影响较大,脉冲电压和电脉冲组数影响较弱;脉冲电磁处理后的刀具切削力较未处理有所降低,后刀面磨损速度明显减缓。     

小样产品试织时常见问题处理的探讨

本文结合多年的实践经验，针对纺织专业学生使用江阴通源生产的SGA598型半自动织样机设计试织时，出现的松紧边、锁边问题、张力控制等常见问题进行了探讨。