透射电子显微镜三维重构技术及其在材料研究领域的应用

透射电子显微镜(TEM)三维重构技术是一种基于TEM用以表征材料三维空间结构的分析测试技术。本文对TEM三维重构技术进行简要介绍,并以Tecnai G2F20场发射透射电镜三维重构为例介绍了实际操作过程中的经验及其在纳米、半导体等材料研究领域的应用。     

Structural dimension optimization and mechanical response analysis of fabricated honeycomb plastic pavement slab

Because of favorable mechanical properties, deformation resistance and being conducive to environmental protection, honeycomb fabricated plastic pavement slabs are highly recommended these years. At present, most studies focus on the performance of plastic materials, however, the dimension optimization of fabricated plastic pavement slab is rarely mentioned. In this paper, an optimized geometry of the honeycomb pavement slab was determined through finite element analysis. Mechanical response of honeycomb slabs with different internal dimensions and external dimensions were explored. Several dimension factors were taken into consideration including the side length, rib thickness, the thickness of both top and bottom slabs of honeycomb structure and the length, the width and the thickness of the fabricated plastic slab. The results showed that honeycomb pavement slab with 6 cm bottom slab, 12 cm top slab,18 cm side length and 6 cm rib thickness is recommended, additionally, an external dimension of 4 m × 4 m × 0.45 m is suggested. Then, the mechanical responses of this optimized fabricated plastic slab were further investigated. Significance of different influencing factors, including wheel load, elastic modulus of plastic material, base layer thickness, soil foundation modulus and base layer modulus were ranked.     

Development of a prognostic signature for esophageal cancer based on a novel 7-DNA damage repair genes signature

Esophageal cancer (EC) was an aggressive malignant neoplasm characterized by high morbidity and poor prognosis. Identifying the changes in DNA damage repair genes helps to better understand the mechanisms of carcinoma progression. In this study, by comparing EC samples and normal samples, we found a total of 132 DDR expression with a significant difference. Moreover, we revealed higher expression of POLN, PALB2, ATM, PER1, TOP3B and lower expression of HMGB1, UBE2B were correlated to longer OS in EC. In addition, a prognostic risk score based on 7 DDR gene expression (POLN, HMGB1, TOP3B, PER1, UBE2B, ATM, PALB2) was constructed for the prognosis of EC. Meanwhile, EC cancer samples were divided into 3 subtypes based on 132 DDR genes expressions. Clinical profile analysis showed cluster C1 and C2 showed a similar frequency of T2, which was remarked higher than that in cluster 3. Moreover, we found the immune cell inflation levels were significantly changed in different subtypes of EC. The infiltration levels of T cell CD8+, B cell and NK cells were greatly higher in cluster 2 than that in cluster 1 and cluster 3. The results showed T cell CD4+ infiltration levels were dramatically higher in cluster 1 than that in cluster 2 and cluster 3. Finally, we perform bioinformatics analysis of DEGs among 3 subtypes of EC and found DDR genes may be related to multiple signaling, such as Base excision repair, Cell cycle, Hedgehog signaling pathway, and Glycolysis/Gluconeogenesis. These results showed DDR genes may serve as new target for the prognosis of EC and prediction of the potential response of immune therapy in EC.     

The Potential Toxic Side Effects of Flavonoids

Flavonoids are a class of phytochemical molecules abundant in many plants, fruits, vegetables, and leaves. Flavonoids possess a series of significant biological activities, including anticancer, antioxidant, antiviral, and antiinflammatory properties. They become an important source of dietary supplements and natural health products. Though many studies confirmed the safety of flavonoids, the potential toxicity of flavonoids is still a remarkable field of research to be explored. The enthusiasm for flavonoids expressed by the public has sometimes overlooked their toxicity and also consumed the flavonoids exceeding the body requirements. The current review focused on the potential toxicity of flavonoids to make the public consume flavonoids with caution. This review summarizes the current toxicity which has been reported in vivo and in vitro experiments. The toxicity involves carcinogenicity and mutation, liver and kidney toxicity, and the influence on the thyroid and reproductive function and intestinal flora disorders. The mechanism of toxicity is fully complicated, and current evidence indicates that natural flavonoid glycosides act on different targets with different doses in vivo and in vitro experiments. Though most kinds of flavonoids are considered safe, flavonoids proposed as food supplements need to be assessed their tolerable upper intake level as there have been reports of toxic flavonoids.     

某大型泵站故障停机分析及对策

某一大型泵站机电设备多,系统复杂,又有单、双线输水及小流量自流、启泵加压输水等多种运行方式,运行工况复杂。由于泵站上、下游均无调蓄水库,突发故障停机后,上游水位迅速壅高,危及渠道安全,而下游供水流量骤减,影响受水城市供水安全,因此,避免机组故障停机对泵站运行管理非常重要。本文梳理该泵站自投运以来发生的故障停机,总结、分析故障停机的主要原因及采取的应对措施,旨在为类似泵站或水电站的设计及运行维护管理提供借鉴。     

基于优化机组燃烧配风的脱硝系统优化

随着国家对新能源的大力投入,火电机组的负荷率会逐渐下降,低负荷的小时数会进一步的增加,低负荷时由于制粉系统投运台数少,为了保持燃烧稳定,大部分电厂配风为过氧燃烧,使得低氮燃烧器的低氮作用大大下降,从而引起SCR入口NO x浓度大大增加.通过对锅炉燃烧进行优化,在不改变机组效率的情况下,使机组脱销系统的度电用氨量降低,基本在零投入的情况下有效降低了机组的成本.     

MES表面活性剂的工业化精制工艺

将α-磺基脂肪酸甲酯钠盐（MES）产品（含活性物质70%）在加热熔融的状态下滴加到50~55℃低沸点水溶性有机溶剂中，经冷却、结晶、过滤和干燥，得到高纯MES粉剂产品。考察了低沸点水溶性有机溶剂种类、原料与溶剂的投料质量比、冷却温度和结晶时间等工艺条件对产品回收率、活性物质量分数和过筛率的影响，得到了最佳纯化精制工艺：以甲醇为溶剂，5 kg MES，MES与溶剂的投料质量比为1：3，冷却温度为5℃，结晶时间为120 min，干燥时间60 min，干燥温度45℃，溶剂使用3次。本工艺条件下，所制得MES粉剂产品回收率大于98%，含活性物质量分数大于93.0%，产品在40℃密封保存12 h后，过0.850 mm筛孔的筛，过筛率达100%。     

不同镀层结构钢的耐盐雾腐蚀性能比较

通过盐雾试验模拟潮湿环境,对裸钢试片、电镀锌钢试片、化学镀镍-磷钢试片和化学镀镍-钴-磷钢试片进行了宏观形貌、微观形貌和腐蚀产物成分分析,比较了四个试片的耐盐雾腐蚀性能。结果表明:在盐雾环境中,四个试片均会发生电化学腐蚀,生成不同的腐蚀产物;在盐雾腐蚀周期内,裸钢试片的腐蚀速率最高,化学镀镍-磷钢试片和化学镀镍-钴-磷钢试片的腐蚀速率较低;四个试片在腐蚀过程中的阳极反应和阴极反应不同,腐蚀后的微观形貌存在明显差异。     

基于竹筋-钢筋骨架的人工假顶首层充填厚度研究及现场应用

采用简支梁理论、ANSYS软件数值模拟与现场试验相结合的方法,对竹筋-钢筋骨架人工假顶进行了可行性、受力行为、破坏方式与合理设计参数研究。结果表明,竹筋-钢筋骨架人工假顶结构可有效保护上部充填体,最优充填厚度为4.75 m; 采用竹筋-钢筋配筋方式可兼顾采场稳定性与经济效益,减少支护成本约15%。     

Zn与Mg质量比对热挤压Al-Zn-Mg-Sc显微组织及力学性能的影响

制备了Al-2Mg-0.4Sc、Al-5Mg-0.4Sc、Al-5Mg-2Zn-0.4Sc和Al-5Zn-2Mg-0.4Sc等4种合金并在350℃进行热挤压,通过光学显微镜(OM),X射线衍射(XRD),扫描电子显微镜(SEM)、室温拉伸测试,研究了Zn/Mg比对于Al-Zn-Mg-Sc合金组织与力学性能的影响。结果表明,Zn/Mg比的提高对于铸态晶粒具有细化作用,挤压后发生动态再结晶,晶粒尺寸显著减小,但挤压态晶粒尺寸并未随Zn/Mg比的提高而减小。另一方面,Zn/Mg比的提高使Mg32(Al,Zn)49第二相数量增加,且呈现更明显的网状结构。挤压态Al-Zn-Mg-Sc合金屈服强度随Zn/Mg比的提高而提升,主要由于大量Al3Sc粒子与碎化的第二相呈网状分布于晶界,使第二相强化起到主导作用。