Postsynthesis of hierarchical core/shell ZSM-5 as an efficient catalyst in ketalation and acetalization reactions

Hierarchical core/shell Zeolite Socony Mobil-five (ZSM-5) zeolite was hydrothermally postsythesized in the solution of NaOH and diammonium surfactant via a dissolution-reassembly strategy. The silica and alumina species were firstly dissolved partially from the bulky ZSM-5 crystals and then were in situ reassembled into the MFI-type nanosheets with the structure-directing effect of diammonium surfactant, attaching to the out-surface of ZSM-5 core crystals. The mesopores thus were generated in both the core and shell part, giving rise to a micropore/mesopore composite material. The micropore volume and the acidity of the resultant hybrid were well-preserved during this in situ recrystallization process. Possessing the multiple mesopores and enlarged external surface area, the core/shell ZSM-5 zeolite exhibited higher activity in the ketalation and acetalization reactions involving bulky molecules in comparison to the pristine ZSM-5.     

MW级空间核反应堆系统热管式辐射散热器分析及优化

空间核反应堆是空间核电源和核推进的研究基础,大功率核反应堆的体积和质量一直是限制航空航天设计的重要因素。针对这一问题,本文对MW级空间核反应堆系统热管式辐射散热器进行建模和分析,建立热管式辐射散热器的热阻模型,利用穷举法和遗传算法在给定工况下探讨裸碳纤维翅片长度L_f和厚度δ_f、冷却剂质量流量m、辐射散热器入口温度T_f1对散热器质量M的影响。结果表明,当T_f1＝800 K、L_f＝5 cm、δ_f＝0.16 mm、m＝9 kg/s时,M达到最优,为906.593 kg,优化了0.63%的系统质量。     

X射线照射对人树突状细胞免疫功能的影响

采用免疫荧光标记、流式细胞仪、3^H-TdR掺入和MTT技术,研究χ射线照射对人外周血来源的树突状细胞（DCs）和T细胞免疫功能的影响。结果显示,不同剂量（0．1～0．5Gy）χ射线照射后使DCs的HLA-DR、CD86和CD40分子表达上调,CD80分子表达下调;与其他剂量组相比,O．2Gy照射DCs可调节T细胞CD4／CD8比值,增强T细胞的增殖能力,同时还可提高特异性CTL细胞的杀伤能力。说明0．2Gyχ射线体外照射可一定程度提高受辐射损伤机体的免疫功能,是体外处理治疗性DCs较为合理的剂量。     

Plugging properties and profile control effects of crosslinked polyacrylamide microspheres

In this article, the morphology, particle size, and plugging properties of crosslinked polyacrylamide (CPAM) microspheres were investigated through optical microscopy, scanning electron microscopy (SEM), nuclear‐pore membrane filtration experiments, a micro‐visual model, sandpack experiments, parallel twin‐tube plugging, and oil displacement experiments. The results revealed that the primary particle sizes of the CPAM microspheres ranged from several hundreds of nanometers to 5 μm; however, after the microspheres were fully swelled in water, their sizes increased by approximately five times of their original sizes. As a CPAM microsphere dispersion system had good dispersibility and deformation capabilities, a 1.2 μm nuclear‐pore membrane as well as the deep part of a sandpack tube could be effectively plugged. Consequently, the flow diversion effect was achieved in the vertical and planar directions. When the CPAM microspheres migrated in porous media, they could displace residual oil on the pole wall and water flow channel to realize the synchronization of profile control and coordination and improve recovery efficiency. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43666.     

一种基于QFD的地铁施工风险评估方法

地铁施工过程中一旦发生事故,会带来严重的经济损失和人员伤亡,而对地铁项目的风险评估和有针对性的预防措施能有效提高施工过程中的抗风险能力。文章以质量功能展开(QFD)为分析工具进行地铁风险评估,通过构建二阶质量屋模型来表达分析对象之间的影响关系,并采用相对具有区域规律性的事故类型的相对风险权重作为输入以及以非归一化处理的方式解决了输入点改变带来的不同作业活动下事故类型的权重求和问题,以获得作业活动和风险因素的相对风险权重。最后将理论应用于钻眼爆破开挖作业下的事故类型与风险因素风险分析,计算结果与实际分析相符。     

除草剂田间药效试验推荐用药量的探讨

除草剂经过田间药效试验提出，推荐使用剂量必须准确、可靠。本文根据多年田间药效试验和实践对除草剂推荐用药量做了详细论述。苗后除草剂推荐用量应是在适宜的环境条件下，试验结果如温度15℃～27℃、空气相对湿度65％～90％、风速4m／s以下及杂草敏感期等；不良环境和极好的环境条件下的试验结果不应作为推荐用量的依据；不良环境条件下严重干旱、高温低湿，应加植物油型喷雾助剂；还应严格喷洒技术。苗前除草剂应根据不同质地(沙质土、壤质土、粘质土)、有机质含量(土壤有机质含量3％以下、3％～5％、6％以上)，pH值6以下、pH值7以上、除草剂的理化性质、适宜的持效期等，在干旱条件下采取混土施药等技术来确定推荐用量。喷洒技术要规范。     

Synthesis and characteristics of Ce modified HY/SBA-15 and its desulfurization performance for simulated oil

A composite zeolite HY/SBA-15 has been synthesized by an overgrowth approach, and then doped with Ce by a liquid phase ion exchange process to form the Ce modified HY/SBA-15 catalyst. The synthesized materials were examined by X-ray diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscopy (TEM), BJH analysis and pyridine adsorption Fourier-transform infrared spectroscopy (Py-FTIR). The results showed the existence of two different pores sizes of 1.8 and 6 nm. Thus, the HY/SBA-15 composite includes both microporous and mesoporous structures. Desulfurization activity of the composite materials was evaluated using as simulated oil gas. The results showed that the SO_x adsorption capacity of Ce-HY/SBA-15 was enhanced by 1.97 mg/g compared to HY/SBA-15, which suggested that the Ce plays an important role in the desulfurization of simulated oil over composite zeolite. Furthermore, the Py-FTIR results revealed the relationship between the surface acids and the desulfurization performance. It was found that the weak Lewis acids were important for the improved desulfurization performance, while the Brönsted acids inhibited the desulfurization performance.     

碳化镧锰水解氧化法制备La0.978Mn0.946O3氧化物

碳化镧锰合金在室温常压下进行水解氧化反应,洗涤并在50～80℃烘干得到La(OH)3和Mn3O4纳米粉。探讨了反应温度、反应时间、悬浮液浓度和碳化镧锰颗粒大小对晶粒尺寸的影响。优化工艺条件为:反应温度35℃,反应时间18 h,悬浮液浓度0.1 g/ml,碳化镧锰颗粒小于0.15 mm,得到比表面积为122.6 m2/g的La(OH)3和Mn3O4纳米粉。将该纳米粉分别在400、600、800℃和1 000℃煅烧2 h,最终得到晶化程度较好的La0.978Mn0.946O3氧化物。     

脉冲电沉积SiC/TiN颗粒增强Ni-Mo纳米复合镀层研究

采用脉冲电沉积技术在6061铝合金表面制备SiC/TiN颗粒增强Ni-Mo纳米复合镀层。通过在镀层中引入SiC、TiN纳米颗粒并改变电沉积的平均电流密度和占空比,调控复合镀层的微结构,探讨纳米颗粒增强涂层的成膜过程与晶粒细化机理,研究复合镀层的组织结构与耐蚀性、耐磨性的关系。结果表明:双纳米颗粒的加入使镀层结构由锥状向胞状转变,晶粒尺寸由29.86 nm减小至22.79 nm。其中在电流密度为8 A·dm~(-2),占空比为20%时制备的镀层最为均匀致密且Si C/Ti N颗粒复合量最高,分别为1.3%和3.1%(质量分数)。镀层具有典型的fcc结构且呈现出(111)择优取向,纳米颗粒均匀分散在Ni-Mo基体中。Tafel极化和浸泡试验研究表明Ni-Mo复合镀层的腐蚀电流密度为7.08μA/cm~2,相比之下在电流密度为4、8和12 A·dm~(-2)和占空比为40%、60%下制备的Ni-Mo/Si C-Ti N纳米复合镀层腐蚀电流密度分别为4.68、4.12、5.75、4.37和5.53μA/cm~2,分别降低了34%、42%、19%、38%和21%。研究发现在电流密度为8 A·dm~(-2),占空比为20%下制备的纳米复合镀层表现出最好的耐蚀性。与Ni-Mo镀层相比,SiC/TiN颗粒的引入显著地提升了镀层耐磨性。此外,还对脉冲共沉积机理进行了讨论。     

快淬Nd11Fe72Co8V1.5B7.5合金的研究

快淬速度 18m·s-1的Nd11Fe72 Co8V1.5B7.5薄片经 6 5 0℃× 4min晶化处理后 ,晶粒尺寸约 10 0nm ,该快淬薄片经 6 0 0℃× 4min晶化处理后制成的粘结磁体的磁性能 :Br=0 .6 6T ,JHC =780kA·m-1,(BH) max=6 9kJ·m-3 。