晶体尺寸、形貌和表面粗糙度差异对细胞毒性的影响

随着生物材料在生物组织工程领域的应用,晶体材料对细胞的毒性受到人们的广泛关注.人为可控材料在生物体内的应用也越来越广泛.本文综述了晶体尺寸、形貌和表面粗糙度差异对细胞毒性和损伤的影响,从表面电荷、Zeta电位、表面能、颗粒长径比、比表面积、晶体性质、结晶度和化学界面等角度讨论了不同材料对细胞毒性的影响机制,以期在药物载体、生物材料安全性和一些疾病的预防等方面提供一定的启示.     

Growth Kinetics and Mechanism of TGS Crystals

The growth kinetics of TGS crystals was studied at high supersaturations under the Curie temperature. The kinetics data proved that the crystal growth was mainly controlled by BCF surface diffusion model. The continuous growth was fitted to the growth rate data of (110) face. Its edge energy, Jackson factor, activity energies, kinetic coefficients were calculated.     

Growth Kinetics of Adenine Sulphate Crystals

The kinetics of growth and dissolution of adenine sulphate in 1.5 mol · 1⁻¹ H₂SO₄ at different super- and undersaturations has been studied. The solubility of adenine sulphate in H₂SO₄ was determined over the temperature range 20–50 °C. The growth rate of the (100) face is by about 25% higher than that of (111) and the crystal habit is changed by a high supersaturation almost to a bipyramide. The surface diffusion was determined as a prevailing processes and the BaS model gives the best fit with experimental data.     

Polymorphic Transitions in Crystals: Kinetics

The ideas expressed in the previous paper are further amplified and applied to the kinetics of polymorphic transitions. These ideas are then used to explain the behavior of real crystals observed under the microscope. Some experimental evidence obtained with molecular crystals is presented.     

Shape Transformation of Plastic Crystals under the Effect of Surface Energy. Adamantane in Temperature Gradient Conditions

The spontaneous transformation of a polycrystal into a single crystal at high temperatures is observed with adamantane samples. Since the plastic crystal phase at such temperatures is not elastically strained it is concluded that the process is due to the surplus of surface energy in the system. The spontaneous transformation to the equilibrium form of crystals under temperature gradient conditions is investigated. The effect is established both of the surface energy and the shape of the isothermic surfaces.     

Dissolution Kinetics and Etch Pit Morphology of CaF2 Single Crystals

The effect of temperature and concentration of HCl aqeous solutions on the etching behaviour on the face {111} of CaF₂ single crystals is investigated. It has been observed that the shape and the evolution of etch pits and the values of dissolution rate depend on the etching conditions. From the plots of logarithm of dissolution rate versus inverse of absolute temperature the values of activation energy and the pre-exponential factor for the dissolution process are computed. It has been found that the value of the activation energy and of the pre-exponential factor do not remain constant with acid concentration, but exhibit a minimum for the concentration of 6 N.     

Growth from Solutions and Surface Properties of Anthracene Crystals

Crystallography Reports - The influence of different solvents on the growth of anthracene crystals from solutions and on their morphological quality has been investigated. The dependence of the...     

Surface Coarsening on High-Tc Superconducting Single Crystals

Surface coarsening on high T_c superconducting single crystals is proposed to be due to the effect of impurity adsorption on the collective motion of growth steps. Differential interference contrast microscopy (DICM), scanning tunneling microscopy (STM), and polarized optical microscopy (POM) were used for the surface phenomena observations.     

On the Kinetics of Interface Processes on Silver Halide Crystals

In the present paper the activation energies of the transport of Ag⁺ ions in AgCl and AgBr crystals are calculated with the help of a quantum theoretical equation involving the frequency of the optical phonons of the crystal lattice, the mean coordination number for the diffusing ion, and the vibrational quantum number. Comparison of the calculated activation energies with values available from the literature, which were obtained by measurements of electrical conductivity, dielectric loss, diffusion and mass transfer processes, shows good agreement.     

Application of X-rays to the Study of the Surface Roughness

The paper presents problems of an application of grazing incidence X-ray reflectivity as a tool for investigations of the surface roughness. The theoretical calculations are based on Fresnel theory. The surface roughness reduces the reflected amplitude therefore a damping factor describing an influence of that is introduced into equations. The results of computer simulations have been used for estimation of the measured surface roughness of thin epitaxial Si film and GaAs single crystal.     

On the Surface Quality and Micromorphology of HgBrI Single Crystals

Mercuric Bromoiodide (HgBrI) is the only compound in the HgI₂—HgBr₂ system of solid solutions and it is a candidate material for solid state nuclear radiation detector applications, operating at room temperature. In the present paper we report on the surface morphology of the crystals, grown from the vapour phase, using optical microscopy and optical spectroscopy. This examination aims at the determination of the factors that influence the surface quality of the crystals.     

Properties of Surface Layers in Single Crystals of Calomel

Within the framework of the systematic study of differences in physical properties of the calomel (Hg₂Cl₂) single crystals before and after surface treatment, the differences in the microhardness, the residual stress in the surface layer, and the chemical etching rate were investigated on the (110) and (001) crystal faces. It has turned out that Beilby layer (B-layer) formed during surface treatment is softer, and, on the cleavage surface is harder than the underlying bulk material. The thickness of the B-layer in these samples ranged between 5 anf 7 m̈m. Further it has been found that a tensile residual stress s̀ = 14 Nm^-2 prevails in the surface layer of a polished (110) face to a depth of 70 m̈m and, after grinding, to a depth from 90 to 200 m̈m. On the other hand, a compressive stress has been found in the natural cleavage plane. Experiments on etching the Hg₂Cl₂ crystals with HCl + HNO₃ etching solution have shown that the rate of chemical etching is 2 to 4 times larger on the (110) face than on the (001) face. Differences are very strongly dependent on the experimental conditions and on the real structure of a given surface.     

离子束作用下KDP晶体表面粗糙度研究

为了避免传统加工过程对KDP( Potassium dihydrogen phosphate)晶体表面产生损伤、嵌入杂质等降低晶体抗激光损伤阈值的不利因素,文章探索采用离子束抛光技术实现KDP晶体的加工.本文主要分析了离子束抛光作用下KDP晶体表面粗糙度的演变过程,采用垂直入射和倾斜45°入射两种方式研究KDP晶体表面粗糙度,利用倾斜45°入射的加工方式提高了KDP晶体的表面质量,其表面均方根粗糙度值由初始的3.07 nm减小到了1.95 nm,实验结果验证了离子束抛光加工KDP晶体的可行性.     

Kinetics of Etching of Dislocations in Ferroelectric Ammonium Hydrogen Tartrate Single Crystals

Ferroelectric crystals of Ammonium Hydrogen Tartrate (AHT) have been synthesised using the controlled reaction between NH₄Cl and (CHOHCOOH)₂ by diffusion process in silica gel medium. (010) cleavages of AHT crystals have been etched in 1.0 M and 1.5 M solutions of SrCl₂ solution. The lateral and normal velocities of the growth of pits were measured at different temperatures. The time dependence of the growth of the pit dimensions is found to be linear, whereas the temperature dependence of the growth of pits is found to be exponential, viz. \documentclass{article}\pagestyle{empty}\begin{document}$ \[V = A\,\exp \left({\frac{E}{{kT}}} \right)\] $\end{document}. The dissolution parameters, e.g. the activation energies and the pre-exponential factors for dissolution along the surface and along the dislocation lines have been computed. It is observed that the activation energy (E₁) of dissolution along [001] direction is found to be greater than the activation energy (E_b) along [100] direction and the implications are discussed.     

Surface Order Parameter and Polar Anchoring Energy in Nematic Liquid Crystals

The trends of temperature dependence of the surface order parameter and of the anchoring strength coefficient are theoretically evaluated in the Landau-de Gennes phenomenological theory for nematic liquid crystals. The cases of planar, homeotropic and tilted alignment at a planar limiting surface are considered. It is shown that the cases with surface order parameter greater than the bulk one or smaller than this can occur in function of the phenomenological coefficients in the surface free energy expression. The anchoring strength coefficient, W, diminishes when temperature approaches the nematic-isotropic point, after passing through a maximum in most of cases. The possibility of a non-zero anchoring strength at temperatures above the transition temperature is revealed. The obtained trends of W(T) describe well a large variety of experimental results from literature.     

Photothermal Transformation of Bessel Light Beams in Periodically Polarized Nonlinear Crystals

Crystallography Reports - A mechanism of the formation of a photodeflection response in a periodically polarized nonlinear crystal illuminated by a Bessel light beam (BLB) is considered. The...     

CTAS和CNAS晶体的声表面波特性研究

本文计算了Ca3TaAl3Si2O14(CTAS)和Ca3NbAl3SiO14(CNAS)压电晶体的X,Y和Z切型的声表面波速度、机电耦合系数.计算结果表明:CTAS和CNAS机电耦合系数最高可达1.04;,是石英晶体(最大0.3;)三倍多,而CTAS晶体的声表面波速度(最小值约为3070 m/s)比石英(最小值为3200 m/s)小4.0;.给出声表面波特性比较好的切型,为CTAS和CNAS的声表面波应用提供了理论依据.     

Fredericks Transition in Pure and Nanodoped Surface Stabilized Ferroelectric Liquid Crystals

Recently, ferroelectric liquid crystals (FLCs) doped with nanoparticles have attracted a wide interest not only from a scientific but also from a practical point of view and there is continuously growing interest in the effects caused by doping the ferroelectric nanoparticles. Furthermore, the presence of external fields exhibits a very interesting transition, reported by recent experiments. In this work, we investigate the response of a surface stabilized ferroelectric liquid crystal (SSFLC) doped with ferroelectric nanoparticles to an applied electric field. We assume that the smectic layers consist of uniform planes with a fixed orientation and the system is free from dislocation of constant layer thickness due to nanoparticles. We obtain the threshold field of orientational transition and the maximum deviation of the polarization vectors for a pure and a doped SSFLC medium. Then, we discuss the Fredericks transtion of the system and formation of inhomogeneous texture. It is found that the ferroelectric nanoparticles have significant influences in ordering behavior of a SSFLC medium and the threshold fields are critically changed by doping nanoparticles in the SSFLC, which is fundamental to operation of many liquid crystal devices.