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131.
材质为QT400-15球墨铸铁钳座在拉拔力试验时出现裂纹.通过力学性能测定及金相检验,认为钳座在拉拔力试验时出现的裂纹为球化衰退而引起的质量问题.进一步深入分析,得出该质量问题为浇铸时间过长所致,同时铸造厂的质量意识薄弱也是该问题发生的背景原因之一.提出了改进措施并予以实施,从管理入手,完善生产流程控制并加强相关人员培训,取得了良好的效果,杜绝了该类问题的重复发生. 相似文献
132.
Yury Chesnokov Andrey Mozhaev Roman Kamyshinsky Alexander Gordienko Liubov Dadinova 《International journal of molecular sciences》2022,23(10)
Dps (DNA-binding protein from starved cells) is well known for the structural protection of bacterial DNA by the formation of highly ordered intracellular assemblies under stress conditions. Moreover, this ferritin-like protein can perform fast oxidation of ferrous ions and subsequently accumulate clusters of ferric ions in its nanocages, thus providing the bacterium with physical and chemical protection. Here, cryo-electron microscopy was used to study the accumulation of iron ions in the nanocage of a Dps protein from Escherichia coli. We demonstrate that Fe2+ concentration in the solution and incubation time have an insignificant effect on the volume and the morphology of iron minerals formed in Dps nanocages. However, an increase in the Fe2+ level leads to an increase in the proportion of larger clusters and the clusters themselves are composed of discrete ~1–1.5 nm subunits. 相似文献
133.
在常温常压下,采用脉冲激光作用循环的石墨悬浮液,收集并烘干得到样品B,另一部分用高氯酸进行酸煮提纯提到样品A.对样品A、B分别进行高分辨电子显微镜(HRTEM)和显微拉曼光谱(Micro-Raman)分析.结果表明,部分石墨经激光作用后转变成了具有多重孪晶结构特征的、尺寸为5 nm的金刚石颗粒,同时还得到了非晶碳.高分辨电子显微镜照片证明,石墨转变成纳米金刚石的机理为快速成核长大过程. 相似文献
134.
以硫酸为插层剂、过氧化氢为氧化荆,用化学法制备了膨胀石墨。用扫描电子显微镜(SEM)分析了膨胀石墨的孔状结构,测试了膨胀石墨对纯油的吸附量。结果表明:膨胀石墨具有明显的三级孔状结构,膨胀石墨对原油、齿轮油、液压油和汽油的最大吸附量分别为80、85、60和50g/g,这种结果与油品的粘度有关。 相似文献
135.
Dong‐Hui Yang Lingjun Kong Ming Zhong Jian Zhu Xian‐He Bu 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(3)
The development of cost‐effective and flexible electrodes is demanding in the field of energy storage. Herein, flexible FexOy/nitrogen‐doped carbon films (FexOy/NC‐MOG) are prepared by facile electrospinning of Fe‐based metal–organic gels (MOGs) followed by high‐temperature carbonization. This approach allows the even mixing of fragile coordination polymers with polyacrylonitrile into flexible films while reserving the structural characteristics of coordination polymers. After thermal treatment, FexOy/NC‐MOG films possess uniformly distributed FexOy nanoparticles and larger accessible surface areas than traditional FexOy‐NC films without MOG. Taking advantage of the unique structure, FexOy/NC‐MOG exhibits a superior rate performance (449.8 mA h g?1 at 5000 mA g–1) and long cycle life (629.3 mA h g–1 after 500 cycles at 1000 mA g–1) when used as additive‐free anodes in lithium‐ion batteries. 相似文献
136.
137.
The optimal conditions on the plasma-forming gas flowrate, discharge current and voltage, distance between the plasma-torch nozzle and the metal plate surface for the process of penetration in and vaporization of steel plates by the contracted electric-arc air plasma torch accompanied by water quenching, were determined. The X-ray structural and phase studies as well as Mossbauer and electron microscope studies on the samples treated were performed. It was demonstrated that the vaporized elemental iron was oxidized by the oxygen present in the air plasma jet to form iron oxides (wiistite, magnetite, hematite), which, depending on their mass ra- tios, determined the color of the iron oxide pigments, namely, beginning from light yellow, through deep yellow, light brown, deep brown, violet, red-violet, to black. A high degree of dispersity of the iron oxides is thus produced, with an averaged diameter of the particles below 500 nm, and their defective crystal structure form the basis of their potential application as components of iron-containing catalysts and pigments. 相似文献
138.
Roberta J. Ward David T. Dexter Robert R. Crichton 《International journal of molecular sciences》2022,23(13)
Disturbance of the brain homeostasis, either directly via the formation of abnormal proteins or cerebral hypo-perfusion, or indirectly via peripheral inflammation, will activate microglia to synthesise a variety of pro-inflammatory agents which may lead to inflammation and cell death. The pro-inflammatory cytokines will induce changes in the iron proteins responsible for maintaining iron homeostasis, such that increased amounts of iron will be deposited in cells in the brain. The generation of reactive oxygen and nitrogen species, which is directly involved in the inflammatory process, can significantly affect iron metabolism via their interaction with iron-regulatory proteins (IRPs). This underlies the importance of ensuring that iron is maintained in a form that can be kept under control; hence, the elegant mechanisms which have become increasingly well understood for regulating iron homeostasis. Therapeutic approaches to minimise the toxicity of iron include N-acetyl cysteine, non-steroidal anti-inflammatory compounds and iron chelation. 相似文献
139.
Magdalene K. Ameka William N. Beavers Ciara M. Shaver Lorraine B. Ware Vern Eric Kerchberger Kelly Q. Schoenfelt Lili Sun Tatsuki Koyama Eric P. Skaar Lev Becker Alyssa H. Hasty 《International journal of molecular sciences》2022,23(13)
Adipocyte iron overload is a maladaptation associated with obesity and insulin resistance. The objective of the current study was to determine whether and how adipose tissue macrophages (ATMs) regulate adipocyte iron concentrations and whether this is impacted by obesity. Using bone marrow-derived macrophages (BMDMs) polarized to M0, M1, M2, or metabolically activated (MMe) phenotypes, we showed that MMe BMDMs and ATMs from obese mice have reduced expression of several iron-related proteins. Furthermore, the bioenergetic response to iron in obese ATMs was hampered. ATMs from iron-injected lean mice increased their glycolytic and respiratory capacities, thus maintaining metabolic flexibility, while ATMs from obese mice did not. Using an isotope-based system, we found that iron exchange between BMDMs and adipocytes was regulated by macrophage phenotype. At the end of the co-culture, MMe macrophages transferred and received more iron from adipocytes than M0, M1, and M2 macrophages. This culminated in a decrease in total iron in MMe macrophages and an increase in total iron in adipocytes compared with M2 macrophages. Taken together, in the MMe condition, the redistribution of iron is biased toward macrophage iron deficiency and simultaneous adipocyte iron overload. These data suggest that obesity changes the communication of iron between adipocytes and macrophages and that rectifying this iron communication channel may be a novel therapeutic target to alleviate insulin resistance. 相似文献
140.
采用石墨炉原子吸收光谱法(GFAAs)测定锂离子电池正极材料LiMn2O4中杂质Pb和Cd的含量.探讨了HNO2浓度、Pb和Cd的灰化温度和原子化温度、基体改进剂对测定结果的影响.该方法的操作简单,准确度高,Pb的回收率为91.22%~93.75%,Cd的回收率为96.5%~108.6%;精密度好,两种元素测定的相对标准偏差RSD(n=lO)<5%. 相似文献