用环境友好催化剂合成丙酸异丁酯的研究

报道了以固载杂多酸盐TiSiW12O40/TiO2为环境友好催化剂，对以丙酸和异丁醇为原料合成丙酸异丁酯的反应条件进行了研究。实验表明：TiSiW12O40/TiO2是合成丙酸异丁酯的良好催化剂，最佳反应条件为：n（醇）：n(酸）=1.2:1，催化剂用量为反应物料总质量的2.0%。反应时间1.0h，反应温度106-125℃，上述条件下，丙酸异丁酯的收率可达79.1%。     

TiSiW12O40/TiO2催化合成丙酸正丙酯

研究了固载杂多酸盐TiSiW12O40/TiO2催化丙酸与正丙醇的酯化反应，探讨了催化剂用量，反应时间及醇酸摩尔比对酯收率的影响。当醇酸摩尔比为1.3:1，催化剂的量为醇酸总质量的1.5%。反应时间为1.0h，酯产率可达71.4%以上，采用该催化剂合成丙酸正丙酯不仅酯化反应温度低，反应时间较短，催化剂用量少，而且可较好地回收利用，可降低成本；因此，TiSiW12O40/TiO2是合成丙酸正丙酯的优良催化剂，具有良好的应用前景。     

调质状态下40Cr钢的焊接

在合理制定焊接工艺的基础上，采用R307珠光体耐热钢焊条成功地进行40Cr钢在调质状态下的焊接，解决了通常采用25—13型奥氏体焊条焊接出现的焊缝强度低、焊接接头性能差的问题。     

鄱阳湖湖底沉积物放射性水平

本文报道了1985年鄱阳湖湖底沉积物放射性水平的调查结果。沉积物中 U、Th、~(226)Ra、~(40)(?)和~(137)Cs 的比活度分别为64.8、67.9,58.9、676.1和3.5Bq/kg;用~(137)Cs 测龄方法作了沉积物泥芯垂直深度的年代定位,由此得知1985—1958年对应深度沉积物中 U、Th、~(226)Ra 和~(40)K 的比活度与1957—1930年对应深度沉积物比较无显著性差异;U、Th 和~(226)Ra 的浓集因予分别为5.2×10~413.9×10~4和4.8×10~4L/kg。     

Consumer preference not to choose: Methodological and policy implications

Residential consumers remain reluctant to choose new electricity suppliers. Even the most successful jurisdictions, four US states and other countries, have had to adopt extensive consumer education procedures that serve largely to confirm that choosing electricity suppliers is daunting. Electricity is not unique in this respect; numerous studies find that consumers are generally reluctant to switch brands, even when they are well-informed about product characteristics. If consumers prefer not to choose, opening regulated markets can reduce welfare, even for some consumers who do switch, as the incumbent can exploit this preference by raising price above the formerly regulated level. Policies to open markets might be successful even if limited to industrial and commercial customers, with residential prices based on those in nominally competitive wholesale markets.     

Characterization of Urine Stem Cell-Derived Extracellular Vesicles Reveals B Cell Stimulating Cargo

Elucidation of the biological functions of extracellular vesicles (EVs) and their potential roles in physiological and pathological processes is an expanding field of research. In this study, we characterized USC–derived EVs and studied their capacity to modulate the human immune response in vitro. We found that the USC–derived EVs are a heterogeneous population, ranging in size from that of micro–vesicles (150 nm–1 μm) down to that of exosomes (60–150 nm). Regarding their immunomodulatory functions, we found that upon isolation, the EVs (60–150 nm) induced B cell proliferation and IgM antibody secretion. Analysis of the EV contents unexpectedly revealed the presence of BAFF, APRIL, IL–6, and CD40L, all known to play a central role in B cell stimulation, differentiation, and humoral immunity. In regard to their effect on T cell functions, they resembled the function of mesenchymal stem cell (MSC)–derived EVs previously described, suppressing T cell response to activation. The finding that USC–derived EVs transport a potent bioactive cargo opens the door to a novel therapeutic avenue for boosting B cell responses in immunodeficiency or cancer.     

固液混合铸造Al-40Si合金的显微组织和力学性能

采用固液混合铸造的Al-40Si合金组织细小，合金力学性能明显优于传统铸造和半固态加工合金，并且解决了传统铸造Al-40Si合金铸件难以热加工的问题。在本工艺条件下，当添加平均粒度为120μm的粉末且粉末添加量与合金熔体质量比为1时，Al-40Si合金中的初晶硅平均粒度可控制在30μm以下；材料的室温力学性能为：σb=119.6MPa，σ0．2=105MPa，δ=1．43％。     

Application of an analytical phase transformation model

Employing isothermal and isochronal differential scanning calorimetry, an analytical phase transformation model was used to study the kinetics of crystallization of amorphous Mg82.3Cu17.7 and Pd40Cu30P20Ni10 alloys. The analytical model comprised different combinations of various nucleation and growth mechanisms for a single transformation. Applying different combinations of nucleation and growth mechanisms, the nucleation and growth modes and the corresponding kinetic and thermodynamic parameters, have been determined. The influence of isothermal pre-annealing on subsequent isochronal crystallization kinetics with the increase of pre-annealing can be analyzed. The results show that the changes of the growth exponent, n, and the effective overall activation energy Q, occurring as function of the degree of transformation, do not necessarily imply a change of nucleation and growth mechanisms, i.e. such changes can occur while the transformation is isokinetic.     

磷钨钼杂多酸掺杂聚苯胺催化合成丁醛乙二醇缩醛

报道了以磷钨钼杂多酸掺杂聚苯胺为催化剂,通过丁醛和乙二醇反应合成了丁醛乙二醇缩醛。系统考察了醛醇物质的量比、催化剂用量以及反应时间诸因素对产品收率的影响。确定适宜的工艺条件为n(丁醛)∶n(乙二醇)=1∶1.5,催化剂的质量为反应物料总质量的0.8%,反应时间1.0 h。在此反应条件下,丁醛乙二醇缩醛的收率可达71.1%。     

H4SiW12O40-PAn催化剂催化合成苯甲醛乙二醇缩醛

报道了以自制的H4SiW12 O40 (硅钨酸 ) -PAn (聚苯胺 )为催化剂 ,通过苯甲醛和乙二醇为原料合成了苯甲醛乙二醇缩醛。实验表明 :合成苯甲醛乙二醇缩醛适宜反应条件为 :n(苯甲醛 ) /n(乙二醇 ) =1 /2 .0 ,催化剂用量为反应物料总质量的 1 .0 % ,环己烷为带水剂 ,反应时间 1 .0h。上述条件下 ,苯甲醛乙二醇缩醛的收率可达 86.7% .