Regulation of peripheral spindle movement and spindle rotation during mouse oocyte meiosis: new perspectives.

Spindle movement, including spindle migration during first meiosis and spindle rotation during second meiosis, is essential for asymmetric divisions in mouse oocytes. Previous studies by others and us have shown that microfilaments are required for both spindle migration and rotation. In the present study, we aimed to further investigate the mechanism controlling spindle movement during mouse oocyte meiosis. By employing drug treatment and immunofluorescence microscopy, we showed that dynamic microtubule assembly was involved in both spindle migration and rotation. Furthermore, we found that the calcium/CaM/CaMKII pathway was important for regulating spindle rotation.     

Synthesis of aza-fused polycyclic quinolines via double C-H bond activation

Simple but efficient: Aza-fused polycyclic quinolines were efficiently assembled through rhodium(III)-based direct double C-H activation of N-aryl azoles followed by cyclization with alkynes without heteroatom-assisted chelation. Copper(II) acetate, aside from acting as an oxidant, could also play an important role in the C-H activation process.     

Elastic property and intrinsic hardness of novel superhard ternary nitrides (CSi2N4 and SiC2N4)

In this work, the new ternary nitrides (CSi₂N₄ and SiC₂N₄) are designed by the substitution method. The structures, elastic properties, intrinsic hardness and Debye temperature of the new ternary nitrides (CSi₂N₄ and SiC₂N₄) are studied by first-principles calculations based on the density-functional theory. The elastic constants C_ij$C_{ij}$ of these new ternary nitrides are obtained using the stress–strain method. Derived elastic constants, such as bulk modulus, shear modulus, Young's modulus, Poisson coefficient and brittle/ductile behavior are estimated using Voigt–Reuss–Hill theories. The results indicate that γ-CSi₂N₄, p-CSi₂N₄ and p-SiC₂N₄ are mechanically stable. Calculated B/G$B/G$ values and Poisson's ratio for γ-CSi₂N₄, p-CSi₂N₄ and p-SiC₂N4 indicate that these materials are brittle. The calculated anisotropy parameters indicate that γ-CSi₂N₄ shows weak anisotropy and p-SiC₂N₄ and p-CSi₂N₄ have larger anisotropy. Based on the microscopic hardness model, p-CSi₂N₄, p-SiC₂N₄ and γ-CSi₂N₄ should be viewed as superhard materials with some peculiar mechanical properties.     

Asymmetric assembly of 2-oxindole and α-angelica lactone units to construct vicinal quaternary chiral centers

The first organocatalytic asymmetric assembly of Morita-Baylis-Hillman carbonates of isatins and α-angelica lactone has been studied, affording multifunctional products containing two valuable pharmacophores and vicinal quaternary chiral centers in high stereoselectivity (up to 92% ee, dr >95:5).     

超声波作用下乙酸辛酯合成条件的研究

在超声波作用下,不用溶剂,以硫酸氢钠为催化剂催化合成乙酸辛酯。最佳反应条件是:正辛醇和乙酸的物质的量比为1∶2.0,催化剂用量为反应物总质量的1.0%,超声时间20min,反应温度84℃。在此反应条件下,酯收率可达80.1%,催化剂可重复使用。     

原位稀土修饰Bi2MoO6高效可见光催化剂

采用原位法制备了系列稀土离子修饰的Bi₂MoO₆可见光催化剂并应用于罗丹明B的光催化降解,HPLC-MS显示该反应经脱除乙基的过程形成5个中间产物,最后完全矿化。研究表明,Gd³⁺修饰效果最佳,且原位法优于浸渍法,主要归因于Gd³⁺进入Bi₂MoO₆晶格,形成施主能级,导致能级带隙变窄,不仅有利于可见光活化光催化剂,而且阻碍电子-空穴复合并抑制修饰剂流失,从而提高光催化活性和稳定性。     

抽运功率密度对布里渊放大的影响

利用瞬态包含抽运抽空的SBS理论模型对布里渊放大器进行了数值模拟,给出了能量提取效率、Stokes种子光放大率、Stokes种子光脉宽压缩率和抽运光脉宽压缩率随抽运功率密度的变化规律.并用实验进行了验证,理论与实验符合得较好. 关键词： 布里渊放大器 能量提取效率 抽运功率密度     

大口径毛细管气相色谱法快速测定MRS肉汤培养基中水溶性胆固醇

建立了MRS肉汤培养基中水溶性胆固醇的气相色谱测定法.1mL样品(含水溶性胆固醇的MRS肉汤培养基)与5mL 0.5mol/L KOH-甲醇溶液混合,然后于60℃水浴皂化30min.产物游离胆固醇经5mL甲苯萃取后,采用HP-5大口径石英毛细管柱(30m×0.53mm i.d.×1.5μm)进行分离、FID检测器进行检...