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A concise and efficient one-pot synthesis of multi-halogen pyrazino[1,2- a]indole-1,8(2 H,5 aH)-dione ( MHPID) derivatives by the reaction of an enamino ester with multi-halogen benzoquinone derivatives is described. MHPIDs 3a-3d were obtained with good yields (78-83%) by refluxing enamino esters 1a and 1b and tetrahalogen-1,4-benzoquinones 2a and 2b for 24 h without the use of catalysts. Compounds 3e-3p were also obtained with excellent yields (69-92%) via the reaction of the phenyl-substituted enamino esters 1c-1h with tetrahalogen-1,4-benzoquinones 2a and 2b in CH3CN catalyzed by Cs2CO3. These two protocols are efficient and effective for the synthesis of MHPIDs. [ABSTRACT FROM AUTHOR]

Kinesins are molecular motors that require a divalent metal ion (for example, Mg2+) to convert the energy of ATP hydrolysis into directed force production along microtubules. Here we present the crystal structure of a recombinant kinesin motor domain bound to Mn2+ and ADP and report on a serine-to-cysteine substitution in the switch 1 motif of kinesin that allows its ATP hydrolysis activity to be controlled by adjusting the ratio of Mn2+ to Mg2+. This mutant kinesin binds ATP similarly in the presence of either metal ion, but its ATP hydrolysis activity is greatly diminished in the presence of Mg2+. In human kinesin-1 and kinesin-5 as well as Drosophila melanogaster kinesin-10 and kinesin-14, this defect is rescued by Mn2+, providing a way to control both the enzymatic activity and force-generating ability of these nanomachines. [ABSTRACT FROM AUTHOR]

Diamond-copper/steel matrix abrasive composites were prepared by the roll-bonding technique. Firstly, the effects of the roll-bonding technical parameters (including sintering parameters, rolling parameters, and the component content) on the interfacial bonding strength in the composites were researched. Then, the surface macroscopic characteristics of the composites and the microstructures of the bonding interfaces were observed. The static compressive strength of the diamonds in the composites and the grinding performance of the composites were measured. Finally, the mechanisms for the effects of the roll-bonding technical parameters on the interfacial bonding strength were explored. The results showed that with increasing those parameters, the interfacial bonding strength between diamonds and the matrices displayed an initial increase and then a significant decrease. Furthermore, the optimal interfacial bonding strength (11.4 kN/m) and an excellent grinding performance (abrasive ratio of 23.2) were obtained from the diamond-steel matrix composites containing 10 vol% binder and 25% concentration of diamonds, when sintered at the temperature of 900 °C for holding time of 30 min and cold rolled at the reduction rate of 70%. The composites prepared with the optimum technical parameters had acceptable surface smoothness. In addition, the diamonds could be dispersed homogeneously in the matrices and firmly adhered to the substrates. When the diamond concentration was 25% in cold-rolling, the diamond-steel matrix composites showed better grinding performance. By improving the pressure condition of metallurgical bonding between diamonds and metal matrices from static pressure to rolling dynamic pressure, the sintering condition of temperature and holding time can be reduced and shortened, and the sintering condition effect on the interfacial bonding can be weaken. Thus, the application of the roll-bonding technique to the preparation of diamond-metal matrix composites could effectively avoid the thermal damage of diamonds caused by sintering process. [ABSTRACT FROM AUTHOR]

Si-based multilayer structures are widely used in current microelectronics. During their preparation, some inhomogeneous residual stress is induced, resulting in competition between interface mismatching and surface energy and even leading to structure failure. This work presents a methodological study on the measurement of residual stress in a multi-layer semiconductor heterostructure. Scanning electron microscopy (SEM), micro-Raman spectroscopy (MRS), and transmission electron microscopy (TEM) were applied to measure the geometric parameters of the multilayer structure. The relationship between the Raman spectrum and the stress/strain on the [100] and [110] crystal orientations was determined to enable surface and cross-section residual stress analyses, respectively. Based on the Raman mapping results, the distribution of residual stress along the depth of the multi-layer heterostructure was successfully obtained. [ABSTRACT FROM AUTHOR]

Abstract: Silica-coated ultrafine diamond (UFD/SiO2) composites were prepared, which were core/shell structures with amorphous silica shell of approximately 5nm thickness. Contrasting to the pristine UFDs, the dispersion stability of the UFD/SiO2 composites was improved greatly in the multi-component inorganic salts aqueous solution, and the chemical compositions of the ceramic matrix were introduced by multi-component inorganic salts. Meanwhile, the oxidation resistance temperature of the coated UFDs was also increased by around 101.0°C. Furthermore, by using the polyacrylamide gel method and hot-press sintering process, ceramic composites were fabricated with the UFD/SiO2 aqueous suspension containing multi-component inorganic salts. The results indicated that the UFDs coated with silica could be dispersed uniformly in ceramic matrix, where no obvious UFD agglomerates were observed. [Copyright &y& Elsevier]

Several previous trials from Western population studies have showed that statins may help reduce blood pressure (BP). However, randomized clinical data is limited. Xuezhikang, a partially extract of red yeast rice, contains a family of naturally occurring statins, and has a marked impact on lipids, but it is unknown whether Xuezhikang has any effect on BP during long-term follow-up in the Chinese population. This is a post-hoc subgroup analysis of a randomized, double-blinded, placebo-controlled, parallel group clinical trial, Chinese Coronary Secondary Prevention Study (CCSPS). A total of 2704 hypertensive patients with previous myocardial infarction (MI) were assigned either to placebo (n === 1341) or to Xuezhikang (n === 1363) daily for an average of 4.5 years. The primary outcome was the unadjusted changes in mean arterial pressure (MAP) from baseline to 6 months. We also assessed systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure. Analysis of covariance was used to calculate the adjusted effects of treatment on changes in these outcomes at 6, 12, 24, and 48 months post-random- ization, after controlling for potential confounders. This analysis included 2704///4870 (55.5%%%) hypertensive patients for whom BP was measured at baseline and at least one follow-up visit after randomization. Median duration of the follow-up was 4.5 years (54 months), and 25 patients (0.92%%%) were lost to the last follow-up because of adverse effects. The results showed that the unadjusted and adjusted changes in MAP, SBP, DBP, or pulse pressure from baseline were not significantly different for Xuezhikang or placebo recipients at 6, 12, 24, and 48 months after randomization. In this post-hoc subgroup analysis, we failed to demonstrate any significant reducing effects of Xuezhikang on BP in Chinese hypertensive patients with previous MI, suggesting that further prospective study on the effects of statins on BP would be needed, especially in high-risk patients. [ABSTRACT FROM AUTHOR]