Confocal Microscopy Studies of Trypsin Immobilization on Porous Glycidyl Methacrylate Beads

The immobilization of trypsin on porous glycidyl methacrylate (GMA–GDMA) beads has been investigated. In particular, the distribution within the beads of trypsin and of dextran used for hydrophilizing the bead surface prior to protein immobilization was investigated with confocal microscopy. For the system investigated, the fluorescence intensity profiles obtained when using borate buffer as an ambient solution displayed a distinct minimum at the center of the beads, irrespective of the observation depth. However, by reduction of the refractive index difference between the solution and the beads through the addition of glucose to the aqueous solution, artifacts relating to optical length differences could be reduced. For both low molecular weight fluorescein isothiocyanate (FITC), FITC-labeled trypsin, and FITC-labeled dextran, an essentially homogeneous distribution throughout the beads was observed. This simple “contrast matching” method seems therefore to be an interesting tool when investigating the distribution of immobilized protein in porous chromatography media.     

Multi-frequency harmonic arrays: initial experience with a novel transducer concept for nonlinear contrast imaging

Nonlinear contrast imaging modes such as second harmonic imaging (HI) and subharmonic imaging (SHI) are increasingly important for clinical applications. However, the performance of currently available transducers for HI and SHI is significantly constrained by their limited bandwidth. To bypass this constraint, a novel transducer concept termed multi-frequency harmonic transducer arrays (MFHA's) has been designed and a preliminary evaluation has been conducted. The MFHA may ultimately be used for broadband contrast enhanced HI and SHI with high dynamic range and consists of three multi-element piezo-composite sub-arrays (A-C) constructed so the center frequencies are 4f(A) = 2f(B) = f(C) (specifically 2.5/5.0/10.0 MHz and 1.75/3.5/7.0 MHz). In principle this enables SHI by transmitting on sub-array C receiving on B and, similarly, from B to A as well as HI by transmitting on A receiving on B and, likewise, from B to C. Initially transmit and receive pressure levels of the arrays were measured with the elements of each sub-array wired in parallel. Following contrast administration, preliminary in vitro HI and SHI signal-to-noise ratios of up to 40 dB were obtained. In conclusion, initial design and in vitro characterization of two MFHA's have been performed. They have an overall broad frequency bandwidth of at least two octaves. Due to the special design of the array assembly, the SNR for HI and SHI was comparable to that of regular B-mode and better than commercially available HI systems. However, further research on multi-element MFHA's is required before their potential for in vivo nonlinear contrast imaging can be assessed.     

Processing of Spectropolarization Video Images

This paper considers the possibilities and results of using spectropolarization video photography of scenes for discriminating artificial and natural objects. A number of new methods for processing spectropolarization video images are proposed.     

Dipolar contrast for dense tissues imaging

A new type of contrast called dipolar contrast is obtained by a decrease in the dipolar line broadening of protons. This contrast is usable for dense tissue NMR imaging and more generally for the study of dipolar linked protons in biological tissues. The sequence used is based on a variant of the Magic Sandwich Echoes (MSE) technique. In vitro experiments on a tendon sample are used to reinforce the image intensity of regions where the direct proton dipolar interaction exists.     

Computer-generated holograms with a commercial microfilm

We have successfully used a commercial microfilm to produce good quality two-dimensional and three-dimensional computer-generated binary holograms.     

Optimisation of alignment materials for minimising residual retardation in in-plane switching liquid crystal display

The light leakage in a black state of in-plane switching (IPS) liquid crystal display (LCD) associated with rubbing process has been investigated. The mechanical rubbing process with a cloth caused orientation disorders in the liquid crystal directors and these partial orientation disorders result in residual retardations of the IPS LCD, causing the light leakages at the black state. In this study, we theoretically estimated how the light leakage is associated with the rubbing uniformity using 2 × 2 Jones matrix equation and also experimentally confirmed how it is associated with structural properties of the alignment layer. The light leakage was clearly reduced in the alignment layer with reduced crystallinity and flexibility.     

Polymer-assisted nanoparticulate contrast-enhancing materials

The application of nanotechnology in medicine research has significant potential in modern biomedical research,disease diagnosis and therapy.Organic fluorophore-based detection techniques have been widely used as imaging and signal transduction tools for the detection of trace levels of analytes.The photosensitivity of the fluorophores,however,limits their application in such complex environments as living bio-systems where degradation or photobleaching occurs.Inorganic nanoparticles have unique and stable ...     

高分子辅助的纳米粒子造影增强材料

纳米技术和纳米医学的研究在生物医学、疾病诊断和治疗方面显示出了巨大的应用潜力. 有机荧光分子基检测技术已被广泛的用作造影和信号转换的工具用以测定痕量的分析物. 然而, 有机荧光分子基团的降解、光漂白作用使得其荧光的稳定性受到影响, 从而限制了它们在复杂的生理环境中的应用. 无机纳米粒子因其形状、尺寸和组成的不同而具有独特且稳定的光、电、磁及催化性能, 可用作新型的生物纳米造影材料, 能很好的解决造影检测技术所面临的难题. 并且, 纳米造影材料的表面修饰则可以提高它们的在生理条件下的稳定性和靶向生物活性分子的能力.     

利用TeO2减少多模光纤出射场散斑干扰的研究

 为了减少多模光纤出射光场的散斑干扰,提出了把声光布拉格衍射效应所形成的不同衍射级耦合到多模光纤中,由于衍射级具有不同的偏振态,消弱了光场相干条件,进而在出射光场中消弱了散斑场的对比度,并通过对改变声场频率后得到的散斑场对比度的分析,证实了利用各向异性晶体TeO2能够控制散斑场对比度,改善出射场的高斯分布,得出了可以利用布拉格衍射效应减少散斑场干扰的可能性。