不同取代基的噻碳菁和吲哚碳菁染料对其在溴化银微晶上吸附能力及形成J-聚集体尺寸分布的影响

本文研究了５－位不同取代基的噻碳菁和吲哚碳菁染料对其在立方型颗粒和Ｔ－颗粒溴化银微晶上吸附能力的影响，并采用ＡＣＦＥＭ（ＡｎａｌｙｔｉｃａｌＣｏｌｏｒＦｌｕｏｒｅｓｃｅｎｃｅＥｌｅｃｔｒｏｎＭｉｃｒｏｓｃｏｐｙ）研究了上述结构染料对其吸附在溴化银微晶所形成的Ｊ－聚集体尺寸分布的影响．实验结果表明，对吲哚碳菁染料来说，立方体溴化银微晶表面的吸附能力较Ｔ－颗粒溴化银微晶表面的吸附能力强；但对噻碳菁染料来说则相反，它们在Ｔ－颗粒溴化银微晶表面的吸附能力较立方体溴化银微晶表面的吸附能力强．另外，对５－位不同取代基的噻碳菁染料而言，无论是在立方型颗粒或Ｔ－颗粒溴化银微晶上的吸附能力来说，含取代基（无论４－取代基是吸电子型还是推电子型）的噻碳菁染料较未取代的噻碳菁染料强；而５－位取代基是吸电子型的噻碳菁染料更有利于其吸附在Ｔ－颗粒溴化银微晶表面．此外，本文还进一步证明了溴化银微晶表面上染料Ｊ－聚集体的生长过程是符合奥斯瓦尔特成熟过程的．吲哚碳菁染料在Ｔ－颗粒溴化银微晶上形成的Ｊ－聚集体的平均尺寸明显大于在立方体溴化银微晶上形成的Ｊ－聚集体的平均尺寸．吸附在立方体溴化银微晶上的５－不同取代基的噻碳菁染料对其形成Ｊ－聚集体     

光谱增感菁染料自缔合作用的热力学研究——Ⅱ.3,3′-二(γ-磺酸丙基)-9-乙基-4,5,4′,5′-二苯并噻碳菁在DMF-水混合溶剂中J-聚集体生成和J-聚集热

由吸收光谱研究了3,3′-二(丁-磺酸丙基)-9-乙基-4,5,4′,5′-二苯并噻碳菁三乙胺盐(Ⅰ)在DMF-水溶液中生成J-聚集体的效应;直接测量了25℃形成J-聚集体过程的热效应,得到了J-聚集体的聚集热△Hs=—(43±1)×10~3J(表示1摩尔单分子染料连接到J-聚集体上的平均焓变化)。根据Daltrozzo等人将J-聚集体生成当作“结晶”过程的观点,求得该体系中染料I J-聚集体至少包含的染料单分子数n为6。     

短波长菁染料对氯化银乳剂的光谱增感作用

本利用紫外—可见吸收光谱、光谱曝光等手段研究了5种短波长菁染料，比较了它们在氯化银乳剂上的光谱增感作用，得出3种较好的短波长增感染料，并研究它们在氯化银颗粒上的吸附行为．结果表明，这3种染料在氯化银颗粒上均有吸附，并能有效地提高氯化银乳剂在短波长区的感光度．     

桥链含苯并吡喃核的二碳菁染料合成研究

设计了一种新的合成路线,合成了桥链含苯并吡喃核的二碳菁染料。对染料合成的关键和染料性能特点作了分析和探讨。     

菁染料与溴化银相互作用性质的研究

本文用计时电位法及电位滴定研究了十六种不同染料与溴化银之间的相互作用,进一步证明了具有离域π-电子的菁染料才能与卤化银形成络合物的论点。从得到的平衡常数K表明,固体表面上的卤化银-染料与溶液中银离子-染料具有相同键性质,都是银离子与染料离域π-电子作用的结果。     

菁染料和份菁染料的合成及其溶液的光稳定性研究

利用UV－Vis吸收光谱仪和光化学反应器,研究了菁染料和份菁染料的光降解动力学,研究结果表明,染料在乙腈溶液中的光褪色反应遵循假一级或零级动力学衰减,与相应的份菁染料相比,携带正电荷的菁染料具有相对较好的光稳定性。     

菁染料和份菁染料溶液的光降解机理的研究

利用UV－Vis吸收光谱仪和光化学反应器,研究了菁染料和份菁染料溶液的光降解动力学,认为染料在乙腈溶液中的光褪色反应服从假一级或零级动力学,利用GC／MS光谱仪检测了染料的光降解产物,与相应的份菁染料相比,携带正电荷的菁染料具有相对较好的光稳定性,研究结果表明,菁染料光降解反应的中间体可能是染料的半氧化态Dye^ ,并利用纳秒级闪光光解技术研究了Dye^ 的瞬态吸收光谱。     

The Use of Atomic Force Microscopy in Investigating Particle Caking Mechanisms

Spray‐dried materials are being used increasingly in industries such as food, detergent and pharmaceutical manufacture. Spray‐dried sodium carbonate is an important product that has a great propensity to cake; its moisture‐sorption properties are very different to the crystalline and amorphous species, with a great affinity for atmospheric moisture. This work demonstrates how the noncontact surface analysis of individual particles using atomic force microscopy can highlight the possible mechanisms of unwanted agglomeration. The nondestructive nature of this method allows cycling of localised humidity in situ and repeated scanning of the same particle area. The resulting topography and phase scans showed that humidity cycling caused changes in the distribution of material phases that were not solely dependent on topographical changes.     

Characterization of Films with Thickness Less than 10 nm by Sensitivity-Enhanced Atomic Force Acoustic Microscopy

We present a method for characterizing ultrathin films using sensitivity-enhanced atomic force acoustic microscopy, where a concentrated-mass cantilever having a flat tip was used as a sensitive oscillator. Evaluation was aimed at 6-nm-thick and 10-nm-thick diamond-like carbon (DLC) films deposited, using different methods, on a hard disk for the effective Young's modulus defined as E/(1 - ν ²), where E is the Young's modulus, and ν is the Poisson's ratio. The resonant frequency of the cantilever was affected not only by the film's elasticity but also by the substrate even at an indentation depth of about 0.6 nm. The substrate effect was removed by employing a theoretical formula on the indentation of a layered half-space, together with a hard disk without DLC coating. The moduli of the 6-nm-thick and 10-nm-thick DLC films were 392 and 345 GPa, respectively. The error analysis showed the standard deviation less than 5% in the moduli.     

Interfacial Interpretation of Autohesion of Ethylene/1-Octene Copolymers by Atomic Force Microscopy

The T-peel fractured surfaces of bonded films of ethylene/1-octene copolymers with different 1-octene contents were characterized using atomic force microscopy (AFM) and analyzed by fractal analysis. The AFM images showed strong dependence on the bonding temperature, peel rate, and the 1-octene content visually. This dependence has been demonstrated quantitatively by the fractal analyses which quantified an irregular surface by fractal dimensions and characteristic sizes. Two regimes showing fractal features were identified for each surface. In Regime I (higher magnifications) the welding and the following T-peel fracture procedures did little to change the fractal dimensions compared with the original surfaces before welding. But there were significant changes in Regime II (lower magnification) before welding and after T-peel fracture tests. The length scale that separated these two regimes is of the same order as that of polyethylene lamellar crystal structures. This suggests that the amorphous chains interdiffused across the interface while unmelted interfacial crystal structures remain essentially unaltered during the autohesion process. A “stitch-welding” autohesion mechanism was proposed to describe the bonding process in which only chains in the amorphous portions could interdiffuse. During the T-peel fracture tests, a crystal structure on the interface is either pulled over to the other side of the interface due to the interdiffused chains, remains unchanged, or is used as an anchor to pull a crystal structure from the other side of the interface. The characteristic sizes at which the fractal characteristics emerge were shown to be larger for the surfaces fractured at higher peel rates, which corresponds to higher fracture energy. This suggests that the appearance of fractal behavior at larger scales requires higher fracture energies. The characteristic sizes and fractal dimensions were also shown to depend on the molecular structure.     

Interfacial Interpretation of Autohesion of Ethylene/1-Octene Copolymers by Atomic Force Microscopy

The T-peel fractured surfaces of bonded films of ethylene/1-octene copolymers with different 1-octene contents were characterized using atomic force microscopy (AFM) and analyzed by fractal analysis. The AFM images showed strong dependence on the bonding temperature, peel rate, and the 1-octene content visually. This dependence has been demonstrated quantitatively by the fractal analyses which quantified an irregular surface by fractal dimensions and characteristic sizes. Two regimes showing fractal features were identified for each surface. In Regime I (higher magnifications) the welding and the following T-peel fracture procedures did little to change the fractal dimensions compared with the original surfaces before welding. But there were significant changes in Regime II (lower magnification) before welding and after T-peel fracture tests. The length scale that separated these two regimes is of the same order as that of polyethylene lamellar crystal structures. This suggests that the amorphous chains interdiffused across the interface while unmelted interfacial crystal structures remain essentially unaltered during the autohesion process. A “stitch-welding” autohesion mechanism was proposed to describe the bonding process in which only chains in the amorphous portions could interdiffuse. During the T-peel fracture tests, a crystal structure on the interface is either pulled over to the other side of the interface due to the interdiffused chains, remains unchanged, or is used as an anchor to pull a crystal structure from the other side of the interface. The characteristic sizes at which the fractal characteristics emerge were shown to be larger for the surfaces fractured at higher peel rates, which corresponds to higher fracture energy. This suggests that the appearance of fractal behavior at larger scales requires higher fracture energies. The characteristic sizes and fractal dimensions were also shown to depend on the molecular structure.     

Neuron Biomechanics Probed by Atomic Force Microscopy

Mechanical interactions play a key role in many processes associated with neuronal growth and development. Over the last few years there has been significant progress in our understanding of the role played by the substrate stiffness in neuronal growth, of the cell-substrate adhesion forces, of the generation of traction forces during axonal elongation, and of the relationships between the neuron soma elastic properties and its health. The particular capabilities of the Atomic Force Microscope (AFM), such as high spatial resolution, high degree of control over the magnitude and orientation of the applied forces, minimal sample damage, and the ability to image and interact with cells in physiologically relevant conditions make this technique particularly suitable for measuring mechanical properties of living neuronal cells. This article reviews recent advances on using the AFM for studying neuronal biomechanics, provides an overview about the state-of-the-art measurements, and suggests directions for future applications.     

An Atomic Force Microscopy Study of the Wetting of an Inorganic Surface by Latex Particles

Atomic Force Microscopy is used to investigate the wetting of a calcium carbonate crystal surface by latex particles when dried from dispersion. The measured particle heights are found to depend on the scanning rate and on the force of the probe tip acting on the sample. The analysis of the particle profile shows that the spreading is not governed by capillary forces. Below their glass temperature, the latex particles have weak adhesion to the crystal and are moved easily by the probe tip. This results in tip-induced organization of particles. Above their glass temperature, the particles spread on the surface and they are no longer moved by the probe tip.     

Atomic Force Microscope Techniques for Adhesion Measurements

The Atomic Force Microscope (AFM) has become a powerful apparatus for performing real-time, quantitative force measurements between materials. Recently the AFM has been used to measure adhesive interactions between probes placed on the AFM cantilever and sample surfaces. This article reviews progress in this area of adhesion measurement, and describes a new technique (Jump Mode) for obtaining adhesion maps of surfaces. Jump mode has the advantage of producing fast, quantitative adhesion maps with minimal memory usage.     

Atomic Force Microscope Techniques for Adhesion Measurements

The Atomic Force Microscope (AFM) has become a powerful apparatus for performing real-time, quantitative force measurements between materials. Recently the AFM has been used to measure adhesive interactions between probes placed on the AFM cantilever and sample surfaces. This article reviews progress in this area of adhesion measurement, and describes a new technique (Jump Mode) for obtaining adhesion maps of surfaces. Jump mode has the advantage of producing fast, quantitative adhesion maps with minimal memory usage.     

Probing Specific Interaction Forces Between Human IgG and Rat Anti-Human IgG by Self-Assembled Monolayer and Atomic Force Microscopy

Interaction forces between biological molecules such as antigen and antibody play important roles in many biological processes, but probing these forces remains technically challenging. Here, we investigated the specific interaction and unbinding forces between human IgG and rat anti-human IgG using self assembled monolayer (SAM) method for sample preparation and atomic force microscopy (AFM) for interaction force measurement. The specific interaction force between human IgG and rat anti-human IgG was found to be 0.6–1.0 nN, and the force required for unbinding a single pair of human IgG and rat anti-human IgG was calculated to be 144 ± 11 pN. The results are consistent with those reported in the literatures. Therefore, SAM for sample preparation combined with AFM for interaction measurement is a relatively simple, sensitive and reliable technique to probe specific interactions between biological molecules such as antigen and antibody.     

Atomic Force Microscopy (AFM) Applications in Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is an inherited heart muscle disorder characterized by progressive replacement of cardiomyocytes by fibrofatty tissue, ventricular dilatation, cardiac dysfunction, arrhythmias, and sudden cardiac death. Interest in molecular biomechanics for these disorders is constantly growing. Atomic force microscopy (AFM) is a well-established technic to study the mechanobiology of biological samples under physiological and pathological conditions at the cellular scale. However, a review which described all the different data that can be obtained using the AFM (cell elasticity, adhesion behavior, viscoelasticity, beating force, and frequency) is still missing. In this review, we will discuss several techniques that highlight the potential of AFM to be used as a tool for assessing the biomechanics involved in ACM. Indeed, analysis of genetically mutated cells with AFM reveal abnormalities of the cytoskeleton, cell membrane structures, and defects of contractility. The higher the Young’s modulus, the stiffer the cell, and it is well known that abnormal tissue stiffness is symptomatic of a range of diseases. The cell beating force and frequency provide information during the depolarization and repolarization phases, complementary to cell electrophysiology (calcium imaging, MEA, patch clamp). In addition, original data is also presented to emphasize the unique potential of AFM as a tool to assess fibrosis in cardiac tissue.