Study on flow characteristics of solid/liquid system in lysozyme crystal growth

During the process of lysozyme protein crystallization with batch method, the macroscopic flow field of solid/liquid system was observed by particle image velocimetry (PIV). Furthermore, a normal growth rate of (110) face and local flow field around a single protein crystal were obtained by a long work distance microscope. The experimental results showed that the average velocity, the maximal velocity of macroscopic solid/liquid system and the velocity of local flow field around single protein crystal were fluctuant. The effective boundary layer thickness delta(eff), the concentration at the interface Q and the characteristic velocity V were calculated using a convection-diffusion model. The results showed that the growth of lysozyme crystal in this experiment was dominated by interfacial kinetics rather than bulk transport, and the function of buoyancy-driven flow in bulk transport was small, however, the effect of bulk transport in crystal growth had a tendency to increase with the increase of lysozyme concentration. The calculated results, also showed that the order of magnitude of shear force was about 10(-21) N, which was much less than the bond force between the lysozyme molecules. Therefore the shear force induced by buoyancy-driven flows cannot remove the protein molecules from the interface of crystal.

An auto-focusing method for imaging ellipsometry system

An auto-focusing method based on the image brightness gradient sharpness function is presented for imaging ellipsometry system, in which the image plane of the thin-film specimen is not perpendicular to the optical axis. The clear image of a specimen with large area is obtained by moving the imaging sensor in optical axis direction and around its sensitive surface centre successively. The experimental results demonstrate its feasibility.

A novel method to measure coma aberration of projection system

A novel method to measure coma aberration by pattern displacements at different defocus positions is proposed in this paper. The effect of defocus on coma-induced pattern displacement is analyzed. The measuring principle of the method is described in detail. Using the simulation program PROLITH, the proportionality factors between pattern displacement and coma aberration at different defocus positions are calculated. It is proved that the method is simple to perform and the measurement accuracy of coma can increase approximately by 25% by this novel method. (c) 2006 Elsevier GmbH. All rights reserved.

A novel method for measuring the coma of a lithographic projection system by use of mirror-symmetry marks

A novel method for measuring the coma of a lithographic projection system is proposed and the principle of the method is described. By utilizing mirror-symmetry marks, the adverse effects of axial aberrations on the coma measurement are avoided. Experimental results demonstrated that the method has high accuracy. Compared with TAMIS, the conventional technique used for coma measurement, the method is more reliable because the influences of the process factors on the lateral displacements have been considered. (c) 2006 Elsevier Ltd. All rights reserved.

IMPROVED PEAK POWER METHOD FOR MEASURING FREQUENCY RESPONSES OF PHOTODETECTORS IN A SELF-HETERODYNE SYSTEM

An improved peak power method for measuring frequency responses of photodetectors in a self-heterodyne system consisting of a distributed Bragg reflector laser is proposed. The time-resolved spectrum technique is used to measure the peak power of the beat signal and the intrinsic linewidth of heat signal for calibration. The experimental results show that the impact of the thermal-induced frequency drift, which is the main reason for producing an error in measurement by conventional peak power method and spectrum power method, can be removed.

Damage assessment and preservation of suspending system of Yongle-Big-Bell

The Yongle-Big-Bell is an exquisite heritage of ancient China and has more than 600 years history. The long history renders the suspending wooden rack serious damage. Therefore, the security is of our great concern. In order to know if the wooden rack is safe or not for the conventional striking in the festival service, a systemic research work has been done. At first the existing deformation and response to the strike of the beetle were measured, and then calculations using method of material mechanics and finite element analysis were conducted. Based on the results of our research, some concluding remarks and suggestion were given: The Yongle-Big-Bell can be struck regularly without urgent danger of collapse. In view of the existence of serious rotten damage, the repair and protection of wooden rack are pressing.

An effective method for enhancing metal-ions' selectivity of ionic liquid-based extraction system: Adding water-soluble complexing agent

Selective extraction-separation of yttrium(Ill) from heavy lanthanides into 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim][PF6]) containing Cyanex 923 was achieved by adding a water-soluble complexing agent (EDTA) to aqueous phase. The simple and environmentally benign complexing method was proved to be an effective strategy for enhancing the selectivity of [C(n)mim] [PF6]/[Tf2N]-based extraction system without increasing the loss of [C(n)mim](+). (c) 2007 Elsevier B.V. All rights reserved.

Colorimetric recognition of the coralyne-poly(dA) interaction using unmodified gold nanoparticle probes, and further detection of coralyne based upon this recognition system

Among the functional nucleic acids studied, adenine-rich nucleic acids have attracted attention due to their critical roles in many biological processes and self-assembly-based nanomaterials, especially deoxyribonucleic acids (abbreviated as poly(dA)). Therefore the ligands binding to poly(dA) might serve as potential therapeutic agents. Coralyne, a kind of planar alkaloid, has been firstly found that it could bind strongly to poly(dA). This work herein reports an approach for visual sensing of the coralyne-poly(dA) interaction. This method was based on the coralyne inducing poly(dA) into the homo-adenine DNA duplex and the difference in electrostatic affinity between single-stranded DNA and double-stranded DNA with gold nanoparticles (GNPs). Furthermore, we applied the recognition process of the interaction between coralyne and poly(dA) into specific coralyne detection with the assistance of certain software (such as Photoshop). A linear response from 0 to 728 nM was obtained for coralyne, and a detection limit of 91 nM was achieved.

Characterization of FeNi3 alloy in Fe-Ni-O system synthesized by citric acid combustion method

Fe-Ni-O samples, with Fe/Ni ratio ranging from 2 to 1/3, were synthesized. Samples synthesized with and without citric acid in the precursor were compared and it was found that the addition of citric acid is the necessary condition for FeNi3 formation; it was found that FeNi3 alloys were formed in these samples even when calcined in an air atmosphere. X-ray diffraction and X-ray photoelectron spectroscopy measurements were used to characterize the samples. Because of the existence of FeNi3 alloys, Fe-Ni-O samples showed strong reactivity to NO and NO + O-2 but were inert to O-2 alone.

Kinetics study on melt grafting copolymerization of LLDPE with acid monomers using reactive extrusion method

Graft copolymerization in the molten state is of fundamental importance as a probe of chemical modification and reactive compatibilization. However, few grafting kinetics studies on reactive extrusion were carried out for the difficulties as expected. In this work, the macromolecular peroxide-induced grafting of acrylic acid and methyl methacrylate onto linear low density polyethylene by reactive extrusion was chosen as the model system for the kinetics study; the samples were taken out from the barrel at five ports along screw axis and analyzed by FTIR, H-1 NMR, and ESR. For the first time, the time-evolution of reaction rate, the reaction order, and the activation energy of graft copolymerization and homopolymerization in the twin screw extruder were directly obtained. On the basis of these results, the general reaction mechanism was tentatively proposed. It was demonstrated that an amount of chain propagation free radicals could keep alive for several minutes even the peroxides completely decomposed and the addition of monomer to polymeric radicals was the rate-controlled step for the graft copolymerization.

Generation of internal and surface waves by seafloor movement in a two layer fluid system

Internal and surface waves generated by the deformations of the solid bed in a two layer fluid system of infinite lateral extent and uniform depth are investigated. An integral solution is developed for an arbitrary bed displacement on the basis of a linear approximation of the complete description of wave motion using a transform method (Laplace in time and Fourier in space) analogous to that used to study the generation of tsunamis by many researchers. The theoretical solutions are presented for three interesting specific deformations of the seafloor; the spatial variation of each seafloor displacement consists of a block section of the seafloor moving vertically either up or down while the time-displacement history of the block section is varied. The generation process and the profiles of the internal and surface waves for the case of the exponential bed movement are numerically illustrated, and the effects of the deformation parameters, densities and depths of the two layers on the solutions are discussed. As expected, the solutions derived from the present work include as special cases that obtained by Kervella et al. [Theor Comput Fluid Dyn 21:245-269, 2007] for tsunamis cased by an instantaneous seabed deformation and those presented by Hammack [J Fluid Mech 60:769-799, 1973] for the exponential and the half-sine bed displacements when the density of the upper fluid is taken as zero.

A kind of extended Korteweg-de Vries equation and solitary wave solutions for interfacial waves in a two-fluid system

This paper considers interfacial waves propagating along the interface between a two-dimensional two-fluid with a flat bottom and a rigid upper boundary. There is a light fluid layer overlying a heavier one in the system, and a small density difference exists between the two layers. It just focuses on the weakly non-linear small amplitude waves by introducing two small independent parameters: the nonlinearity ratio epsilon, represented by the ratio of amplitude to depth, and the dispersion ratio mu, represented by the square of the ratio of depth to wave length, which quantify the relative importance of nonlinearity and dispersion. It derives an extended KdV equation of the interfacial waves using the method adopted by Dullin et al in the study of the surface waves when considering the order up to O(mu(2)). As expected, the equation derived from the present work includes, as special cases, those obtained by Dullin et al for surface waves when the surface tension is neglected. The equation derived using an alternative method here is the same as the equation presented by Choi and Camassa. Also it solves the equation by borrowing the method presented by Marchant used for surface waves, and obtains its asymptotic solitary wave solutions when the weakly nonlinear and weakly dispersive terms are balanced in the extended KdV equation.