RECENT PROGRESS OF NANO-MECHANICAL MAPPING

 Nano-mechanical mapping by atomic force microscopy has been developed as an useful application to measure mechanical properties of soft materials at nanometer scale. To date, the Hertzian theory was used for analyzing force-distance curves as the simplest model among several contact mechanics between elastic bodies. However, the preexisting methods based on this theory do not consider the adhesive interaction in principle, which cannot be neglected in the ambient condition. A new analytical method was introduced to estimate the elasticity and the adhesive energy simultaneously by means of the JKR theory, describing adhesive contact between elastic materials. Poly(dimethylsiloxane) (PDMS) and isobutylene-co-isoprene rubber (IIR) were analyzed to verify the applicable limit of the JKR analysis. For elastic samples such as PDMS, the force-deformation plots obtained experimentally were consistent with JKR theoretical curves. Meanwhile, for viscoelastic samples, especially for IIR, the experimental plots revealed large deviations from JKR curves depending on scanning velocity and maximum loading force. Some nano-rheological arguments were employed based on the difference between these specimens.     

Analytical methods to derive the elastic modulus of soft and adhesive materials from atomic force microcopy force measurements

We present new DMT‐based and JKR‐based methods to derive the elastic modulus of sample surfaces from an atomic force microscope force‐distance curve (DMT: Derjaguin‐Muller‐Toporov, JKR: Johnson–Kendall–Roberts). Application of the methods to the Maugis–Dugdale curves revealed that the JKR‐based method determines very accurate moduli for Maugis' transitional parameter λ > 0.3; however, the DMT‐based method generally estimates much less accurate moduli. The new JKR‐based method has advantages over the two‐point method, which has been often used for the JKR analysis, in capabilities to select the fitting range and to involve more than two points in curve fitting. Utilizing the advantages, for example, one can limit the fitting range to the attractive force zone to reduce the contact area of soft and adhesive materials. The method consists of algebraical calculation and optionally linear fitting; hence, the computational cost is low enough to be applicable to a real‐time JKR analysis method of fast force mapping. The detailed procedure of the method is explained using a force‐distance curve on a poly(dimethylsiloxane) surface. The advantages of the method are demonstrated using a force mapping data on a vulcanized rubber blend. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1279–1286     

甲壳素基新材料研究进展

甲壳素/壳聚糖良好的生物相容性、生物可降解性及独特的生理活性使其成为非常有应用价值的天然高分子材料,当前已成为新材料领域的研究热点.甲壳素/壳聚糖具有良好的可加工性能,可固定贵金属、半导体纳米材料等活性催化物质,同时其本身也具有催化作用,是一类绿色环境友好的高分子催化材料.良好的生物相容性和生物可降解性使甲壳素/壳聚糖...     

固相光度法的研究进展

就固相光度法研究现状，按透射法和反射法介绍了其基本原理和特点，并对近年来的应用和研究进行了回顾和评述，对其发展动向作了展望。     

砷的光度分析法的进展

文中着重介绍了近年来砷的光度测定方法的新进展,包括砷斑法、Ag（DDC）光度法、分单质银分散体系光度法、砷钼蓝光度法等。引用文献85篇。     

麝香酮合成的新进展

本文简要评述了近十年来麝香酮合成的进展     

砷的形态分析方法研究进展

对近年有关砷的形态分析的进展作了综述。对新的分离方法,如毛细管电泳法、氢化物发生法及高效液相色谱法给予了较多的注意,还对各种测定方法作了对比和讨论（引述文献79篇）。     

糖苷化反应研究进展

本文重点介绍了低聚糖合成的各种方法，评述了糖苷化应的各种新进展以及存在的问题。并根据其不同的特点进行了分类。     

铕测定方法的近期进展

对铕测定方法的近期进展作了评述，涉及的测定方法有荧光光度法、吸光光度法、原子发射光谱法、原子吸收光谱法、X-射线荧光光谱法、质谱法及伏安法等。还对该领域的研究动态作了简要讨论（引述文献59篇）。     

Estimating the thickness of hydrated ultrathin poly(o-phenylenediamine) film by atomic force microscopy

A novel method to measure ultrathin poly(o-phenylenediamine) (PPD) film electropolymerized on gold electrode in liquid was developed. It is based on the force versus distance curve (force curve) of atomic force microscopy (AFM). When 1-0.25 μm/s was chosen as the rising rate of the scanner, and 50% of the confidence interval (CI) as the qualifying threshold value, the thickness of the hydrated polymer film could be calculated. This result was compared with one obtained from an AFM image. A step-like electrode fabricated by a photolithographic process was used. The height difference of the electrode before and after the PPD coating was imaged in liquid, and then the real thickness, 19.6±5.2 nm, was obtained. The sample was also measured by estimating the transition range of the force curve of hydrated PPD film, and the thickness of the hydrated PPD film was determined to be 19.3±8.2 nm. However, the results calculated by integrating the electropolymerized charge for the oxidation process of o-phenylenediamine (o-PD) was only one-third as large as it was when using the two previously described methods. This indicated that the structure of hydrated PPD film might have been swollen.     

原子力显微镜原位观察球晶界面上片晶的生长

当结晶聚合物由熔融冷却或从浓溶液中析出结晶时 ,在不存在应力和流动的情况下 ,一般形成球晶 .球晶在一定的生长时期内呈现球形外观 ,在偏光显微镜下通常呈现Maltese黑十字消光图样 .球晶作为一种常见的结晶形态 ,由片晶堆积而成[1,2 ] .Keith和Padden认为形成球晶的体系包含杂质和聚合物链 ,由于杂质在片晶生长界面的富集导致片晶产生小角度分叉 ,这样片晶能填满球状的空间[1,2 ] .近年来的研究表明球晶是由一个片晶开始生长 ,片晶在生长过程中不断的诱导成核使片晶分叉 ,首先形成片晶捆束 ,然后片晶向各个方向发散生长 ,最终形成球晶[3…     

镉的吸光光度法分析进展

从不同结构和种类的显色剂及样品的预处理对镉的吸光光度法测定的近年来的进展进行综述(引述文献76篇)。     

食品添加剂分析方法研究进展

综述了近10年来有关食品添加剂分析的研究状况。内容包括食品中的防腐剂、甜味剂、着色剂、抗氧化剂、漂白剂和发色剂等(引文71篇)。     

修饰碳糊电极研究进展

评述了修饰碳糊电极的材料组成、修饰方法与修饰功能及在分析化学、生物科学、环境化学等领域的应用，预测了修饰碳糊电极在化学生物传感器方面的发展趋势（引用文献54篇）。     

基于AFM的药物刺激前后淋巴瘤活细胞的形貌及弹性的变化

原子力显微镜(AFM)的发明为研究单个活细胞的形貌结构及物理特性提供了新的技术手段.然而,由于缺少合适的固定方法,利用AFM对动物悬浮活细胞的形貌进行高分辨率成像还面临着巨大的挑战.本文提出一种基于微柱阵列和静电吸附相结合的动物悬浮细胞固定方法.通过微柱阵列的机械钳制和多聚赖氨酸的静电吸附实现了对单个淋巴瘤B细胞的固定,并在此基础上利用AFM动态观测了不同浓度Rituximab刺激下淋巴瘤B细胞的表面形貌及弹性的变化.经过0.2 mg·mL-1的Rituximab刺激2 h后,细胞表面的褶皱增加,细胞的杨氏模量从196 kPa减小到183 kPa.经过0.5 mg·mL-1的Rituximab刺激2 h后,细胞形貌发生显著变化并出现突起结构,细胞的杨氏模量从234 kPa减小到175 kPa.实验结果表明淋巴瘤细胞形貌和弹性变化的幅度随着Rituximab刺激浓度的增加而增加,加深了对Rituximab作用效果的认识.     

Interaction between solid surfaces in a polymer melt studied by atomic force microscopy

Using an atomic force microscope (AFM) the interaction between an AFM tip and a planar silicon oxide surface has been measured across poly(dimethylsiloxane) (PDMS, M_W = 18 000). Due to the small radius of curvature of the AFM tip the hydrodynamic repulsion of the tip was negligible and forces could be measured in equilibrium. This is confirmed by the fact that force-versus-distance curves measured at different approaching velocities were indistinguishable. In equilibrium a repulsive force was observed which could best be described by a power law, F ∝ 1/d^2.5 where d is the distance.     

有机HTDIOO分子LB膜结构的AFM研究

利用原子力显微镜（AFM）对有机分子HTDIOO单层和多层LB膜结构进行了观察·实验结果表明，针尖与LB膜表面分子间的相互作用力会对成像的膜结构有影响．当悬臂针尖与LB膜表面分子的相互作用力较大时，针尖会扰动HTDIOO分子在单层LB膜中的有序排列．HTDIOO单层LB膜具有有序结构；而在多层LB膜中，HTDIOO分子则聚集在一起形成了一定的畴结构．     

PDMS-MDI-PEG多嵌段共聚物涂层表面微相分离行为研究

采用两步溶液聚合方法合成了一系列聚二甲基硅氧烷(PDMS)-4,4′-二苯基甲烷二异氰酸酯(MDI)-聚乙二醇(PEG)多嵌段共聚物.利用轻敲模式原子力显微镜(AFM)观察了嵌段共聚物的表明形貌,研究了退火、共聚物组成以及PEG分子量和不同的官能团对涂层表面微相分离行为的影响,同时对微相分离行为的形成机理也作了相应的探讨.研究表明,该嵌段共聚物即使在PDMS含量大于50wt%时,涂层表面仍呈现出规整有序的纳米级相分离结构,其中疏水相和亲水相分别由PDMS链段和MDI-PEG组分构成.     

国内光度法测定铬的进展

综述了1996年以来国内分光光度法测定痕量铬的方法、反应条件和应用,并对今后的发展提出了展望。     

罗丹明类化合物作为分析试剂的应用进展

对近年来罗丹明类化合物作为分析试剂的应用进展作出评述,主要涉及此类试剂在光度法、化学发光法、荧光光度法及共振散射光谱法等领域中的应用近况,引用文献87篇。