电磁场作用下球形磁极辅助研磨弯管内表面研究

弯管弯曲成形后,在弯折处易产生微裂纹、褶皱等表面质量缺陷问题。本文通过采用六自由度机械手拖动电磁场发生装置沿加工轨迹往复运动,电磁场发生装置驱动球形辅助磁极绕管件内壁转动,实现了对弯管内表面的光整加工。在此基础上,通过对弯管轮廓采集及曲线拟合,重新构建了弯管中心线并转换为新的研磨加工轨迹。采用超景深3D电子显微镜和触针式表面粗糙度测量仪对研磨试验前后弯管内表面的形貌和粗糙度进行了对比分析。结果表明,通过重新构建研磨加工轨迹,试验装置有效解决了研磨弯折处的干涉与研磨不均匀等问题。研磨55 min后,表面粗糙度由原始的0.713μm降低到0.194μm,铜合金弯管内表面原始质量缺陷基本去除,表面纹理较为致密均匀。该方法有效避免了未规划研磨轨迹时出现的犁耕等纹理缺陷,提高了弯管的服役可靠性。     

Construction of functional aliphatic polycarbonates for biomedical applications

Aliphatic polycarbonates are one important kind of biodegradable polymers and have been commonly used as integral components of engineered tissues, medical devices and drug delivery systems. As far as the biomedical application is concerned, traditional aliphatic polycarbonates usually suffer from the strong hydrophobicity, deficient functionality, and insufficient compatibility with cell/organs. Consequently, the application is quite limited in scope. Due to the imparted appealing properties, aliphatic polycarbonates bearing specifically designed functional/reactive groups attract great interest from researchers in the recent years. The present review outlines the development up to date concerning the design and biomedical application of functional aliphatic polycarbonates, with an emphasis on their ring-opening (co)polymerization preparation.     

Silicate-based polymer-nanocomposite membranes for polymer electrolyte membrane fuel cells

Proton-exchange membrane fuel cells have emerged as a promising emission free technology to fulfill the existing power requirements of the 21st century. Nafion^® is the most widely accepted and commercialized membrane to date and possesses excellent electrochemical properties below 80 °C, under highly humidified conditions. However, a decrease in the proton conductivity of Nafion^® above 80 °C and lower humidity along with high membrane cost has prompted the development of new membranes and techniques. Addition of inorganic fillers, especially silicate-based nanomaterials, to the polymer membrane was utilized to partially overcome the aforementioned limitations. This is because of the lower cost, easy availability, high hydrophilicity and higher thermal stability of the inorganic silicates. Addition of silicates to the polymer membrane has also improved the mechanical, thermal and barrier properties, along with water uptake of the composite membranes, resulting in superior performance at higher temperature compared to that of the virgin membrane. However, the degrees of dispersion and interaction between the organic polymer and inorganic silicates play vital roles in improving the key properties of the membranes. Hence, different techniques and solvent media were used to improve the degrees of nanofiller dispersion and the physico-chemical properties of the membranes. This review focuses mainly on the techniques of silicate-based nanocomposite fabrication and the resulting impact on the membrane properties.     

Interpolymer radical coupling: A toolbox complementary to controlled radical polymerization

The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular engineering toolbox to the controlled radical polymerization techniques (CRP). Indeed, all structures formed by CRP are likely to be prone to radical coupling reactions, which multiply the available synthetic possibilities. Basically, the coupling systems can be divided in two main categories. The first one, including the atom transfer radical coupling (ATRC), silane radical atom abstraction (SRAA) and cobalt-mediated radical coupling (CMRC), relies on the recombination of macroradicals produced from a dormant species. The second one, including atom transfer nitroxide radical coupling (ATNRC), single electron transfer nitroxide radical coupling (SETNRC), enhanced spin capturing polymerization (ESCP) and nitrone/nitroso mediated radical coupling (NMRC), makes use of a radical scavenger in order to promote the conjugation of the polymer chains. More than a compilation of macromolecular engineering achievements, the present review additionally aims to emphasize the particularities, synthetic potential and present limitations of each system.     

Rapid and selective separation for mixed proteins with thiol functionalized magnetic nanoparticles

ABSTRACT: Thiol group functionalized silica-coated magnetic nanoparticles (Si-MNPs@SH) were synthesized for rapid and selective magnetic field-based separation of mixed proteins. The highest adsorption efficiencies of binary proteins, bovine serum albumin (BSA; 66 kDa; pI = 4.65) and lysozyme (LYZ; 14.3 kDa; pI = 11) were shown at the pH values corresponding to their own pI in the single-component protein. In the mixed protein, however, the adsorption performance of BSA and LYZ by Si-MNPs@SH was governed not only by pH but also by the molecular weight of each protein in the mixed protein.     

磁性螯合树脂制备技术进展

介绍了磁性螯合树脂的结构,重点综述了磁性螯合树脂的制备方法,并分析了其应用前景。     

Probing kinetic mechanisms of protein function and folding with time-resolved natural and magnetic chiroptical spectroscopies

Recent and ongoing developments in time-resolved spectroscopy have made it possible to monitor circular dichroism, magnetic circular dichroism, optical rotatory dispersion, and magnetic optical rotatory dispersion with nanosecond time resolution. These techniques have been applied to determine structural changes associated with the function of several proteins as well as to determine the nature of early events in protein folding. These studies have required new approaches in triggering protein reactions as well as the development of time-resolved techniques for polarization spectroscopies with sufficient time resolution and sensitivity to probe protein structural changes.     

SmCo5垂直磁记录薄膜的研究进展

SmCo5垂直磁化膜具有极高的单轴磁晶各异性,能有效克服当前垂直磁记录介质所面临的超顺磁效应问题,是未来超高密度磁记录介质的候选材料。本文叙述了SmCo5垂直磁记录薄膜制备的国内外发展现状,着重介绍了底层材料和结构对SmCo5垂直磁化膜微观结构和磁性能的影响,同时对今后SmCo5垂直磁记录薄膜的研究方向作了展望。     

定量核磁共振法研究进展

核磁共振法广泛应用于有机化合物的定性分析,但是它在化合物纯度定值、含量测定中也具有很重要的作用,分为一维谱(1H、13C、14N、15N、19F、31PNMR)、二维谱(J-分辨、1H-1H、1H-13C、DOSY)、液相色谱-核磁共振联用法(LC-NMR)、固体NMR等NMR类型。其中,1H谱最常用,其他一维谱对不同化合物各有其优势。二维核磁共振法对于在一维谱图中信号严重重叠的复杂样品的定量分析非常重要。LC-NMR联用技术将高效的分离手段与NMR联用,可以获得复杂样品的信息。介绍了各类定量核磁共振法在各领域的研究进展。     

磁性SO42-/ZrO2/Fe3O4/凹凸棒石固体酸催化剂的制备及催化性能

以凹凸棒石（palygorskite,PAL）黏土为载体,采用共沉淀法制备了SO24-/ZrO2/Fe3O4/PAL固体酸催化剂。利用X射线衍射、透射电子显微镜、能谱和超导量子干涉仪对催化剂进行了表征,并用于催化乙酸正丁酯的反应,考察了Fe3O4、ZrO2含量和煅烧温度对催化剂活性的影响。结果表明：SO24-/ZrO2/Fe3O4/PAL固体酸催化剂具有较高的催化活性和较强的磁性能,磁性材料的引入提高了催化剂活性,对乙酸正丁酯的合成反应活性高达89.26%,使用4次后其酯化率还能达到74.53%。