STUDY OF THE INFLUENCE OF pH ON THE ELECTROCRYSTALLIZATION OF ZINC

1. IntroductionElectrodeposition ofalloys is w idely used in the production of new m aterials possessing specificchem ical,physicalproperties,such asnanocrystalline m agnetic thin film sand functionalm ultilayers[1-5].In com parison to otherdeposition tec…     

Correlations Between Precursor Molecular Weight and Dynamic Mechanical Properties of Polyborosiloxane (PBS)

It is possible to tailor the dynamic response of polyborosiloxanes (PBS) based on picking the right molecular weight of a precursor. The molecular weight of hydroxy-terminated polydimethylsiloxane (PDMS) defines the shear-stiffening performance of PBS due to straightforward condensation reaction between hydroxy end groups of PDMS and boric acid. Introduced borono groups behave as stickers, hence, are prone to supramolecular interactions. New correlations are discovered for five PBS synthesized from hydroxy-terminated PDMS with different molecular weights. Si─O─B infrared band intensities for all PBS follow the same trend with molecular weight as the number of PDMS hydroxy groups which confirms the full completion of the reaction. After synthesis, the molecular weight of PBSs remained almost the same, which indicates the absence of significant chain scissoring, polymerization, or crosslinking. During the rheological analysis, it is found that crossover point modulus follows the same trend as the number of PDMS hydroxy groups and Si─O─B band intensities. PBS demonstrates a linear increase in peak forces with molecular weight during the drop weight impact test. The low molecular weight of a precursor, hence, a high number of stickers is a primary requirement for effective protection against low-velocity impact.     

Mechanisms of Connexin Regulating Peptides

Gap junctions (GJ) and connexins play integral roles in cellular physiology and have been found to be involved in multiple pathophysiological states from cancer to cardiovascular disease. Studies over the last 60 years have demonstrated the utility of altering GJ signaling pathways in experimental models, which has led to them being attractive targets for therapeutic intervention. A number of different mechanisms have been proposed to regulate GJ signaling, including channel blocking, enhancing channel open state, and disrupting protein-protein interactions. The primary mechanism for this has been through the design of numerous peptides as therapeutics, that are either currently in early development or are in various stages of clinical trials. Despite over 25 years of research into connexin targeting peptides, the overall mechanisms of action are still poorly understood. In this overview, we discuss published connexin targeting peptides, their reported mechanisms of action, and the potential for these molecules in the treatment of disease.     

连接工艺参数对镍基高温合金TLP连接接头组织和性能的影响(英文)

以BNi-2为中间层对镍基合金进行过渡液相连接,研究连接工艺参数对接头组织和力学性能的影响。随着连接温度的升高或连接时间的延长,沉淀区的富镍和富铬硼化物数量减少,同时沉淀区晶粒尺寸减小。较高的连接温度或较长的连接时间,有利于降熔元素(B和Si)由沉淀区向母材中的扩散和母材与连接接头间的原子互扩散。当连接温度为1170℃、连接时间为24h时,可以获得与母材化学成分及组织基本相当的连接接头。剪切试验结果表明:室温和高温拉剪强度均随着保温时间的延长而增加,但连接时间对高温拉剪强度的影响要大于对室温拉剪强度。     

X90级管线钢应变时效行为

针对高级管线钢应变时效问题,对X90级直缝埋弧焊管管体不同预应变及时效前后的组织和力学性能进行了对比,研究了应变时效对X90级管线钢组织和力学性能的影响。结果表明：不同应变时效前后X90级管线钢的显微组织和冲击韧性变化不明显;应变时效后拉伸曲线由拱顶型连续曲线转变为吕德斯型屈服曲线,屈服强度增加,屈强比升高;预应变量越大,屈服强度和屈强比升高越显著,且横向性能受到预应变量的影响比纵向要大,而200~250 ℃温度区间时效对屈服强度和屈强比影响较小。     

硫酸盐激发与矿渣改性硬石膏胶结材

充分利用硬石膏胶凝性,开发硬石膏胶结材是对硬石膏资源最合理、有效的利用.本文通过对硬石膏水化率与水化温升测定、比表面积与水化活性关系、硬化体相组成与显微结构分析,重点研究了硫酸盐激发、矿渣改性、粉磨活化对硬石膏胶结材料的影响.结果表明:硫酸盐可以缩短硬石膏凝结时间,提高硬石膏水化率,使硬石膏水化热集中,水化温升增大,硬石膏水化进程加快;矿渣可以促进硬石膏水化,形成钙矾石、水化硅酸钙等水硬性矿物,提高硬石膏胶结材的强度与耐水性;硬石膏溶解水化活性随其分散度增加而提高.采用硫酸盐激发、矿渣改性和粉磨活化可以配制28 d抗压强度32.5 MPa、软化系数0.78的硬石膏胶结材.     

4-硝基苯乙基溴合成

以β-溴苯乙烷为原料,以醋酸、醋酐和发烟硝酸为硝化剂合成4-硝基苯乙基溴。实验考察了反应条件对产品收率的影响。实验表明适宜的反应条件是：反应温度控制在-5℃,0．1mol β-溴苯乙烷需要0．15mol的发烟硝酸和0．12mol醋酐,反应时间为4小时,4-硝基苯乙基溴收率达69．2％。     

频率和磁场强度对非晶及纳米晶合金带材磁性能的影响

研究了频率(f10 kHz)和磁场强度对商业非晶合金1K101和纳米晶合金1K107成品带材铁芯的损耗Pc和幅值磁导率μa的影响。结果表明,两种带材铁芯损耗Pc均正比于磁感应强度B的平方(Pc∝B2)及正比于频率f的平方(Pc∝f2);两种带材铁芯的μa都随B增加到一定值然后下降;当频率f为200 kHz时,1K107合金带材在B为0.4 T时最大幅值磁导率μa=27273.3;1K101合金带材在B=0.7 T时具有最大幅值磁导率μa=6548.9;在相同f、B条件下1K107带材损耗明显小于1K101,即便是f相同、B更大的情况下前者损耗仍可能小于后者,例如P1K107(200 kHz,0.7T)为1302.08 W/kg,P1K101(200 k Hz,0.4T)为2180.36 W/kg,表明纳米晶合金带材的磁性能明显优于非晶合金带材,更适合用于制备高频电力电子变压器铁芯。     

离子共放电沉积法制备Zn-Bi复合镀层及其性能(英文)

采用离子共放电沉积法制备Zn-Bi复合镀层并对其性能进行研究。结果表明,Bi可以有效地抑制电镀过程中Zn晶粒的生长,有利于镀层晶粒的细化,从而使得Zn-Bi复合镀层与纯锌镀层相比具有优异的力学性能。该方法制备的Zn-Bi复合镀层,其显微硬度是纯锌镀层的2倍,同时具有更高的耐磨性。     

n单元同分布冷贮备系统的模糊可靠性

本文从Fuzzy可靠性的基础上.应用模糊数学的原理和方法,建立了n单元同指数分布的冷贮备系统模糊可靠性的公式.