Collagen-hydroxyapatite composite enhances regeneration of calvaria bone defects in young rats but postpones the regeneration of calvaria bone in aged rats

The potential differences in bone repair of calvaria defects treated with a collagen sponge (HELISTAT) or a collagen-hydroxyapatite composite (HEALOS) in young and aged rats were evaluated at 8 weeks after surgery. A histomorphometric analysis of new bone formation and an evaluation of angiogenesis, mast cell, and eosinophil local infiltration were performed. Evaluation showed that HELISTAT induced a similar amount of new bone in both young and aged rats. However this occurred to a lesser degree than in young rats treated with HEALOS. The largest number of blood vessels was present in the defects of aged rats treated with HEALOS, and the number of mast cells was highest in the defects treated with HELISTAT in both young and aged rats. Eosinophils were present to the greatest extent in defects treated with HEALOS in comparison to defects treated with HELISTAT in both young and aged rats. Collagen-hydroxyapatite composite (HEALOS) enhances calvarial bone repair more than collagen sponge alone (HELISTAT) in young rats but not in aged rats at 8 weeks after surgery. HEALOS appears to induce a more intense inflammatory response than HELISTAT especially in aged rats.     

PREPARATION OF TiN FILMS BY N_2 ASSISTED Xe~+ ION BEAM ENHANCED DEPOSITION AND THEIR MECHANICAL PROPERTIES

A new method for preparation of hard TiN films has been developed by using electronbeam evaporation-deposition of Ti and bombardment with 40 keV Xe~+ ion beam ina N_2 gas environment.The synthesized TiN films were superior to PVD and CVDones in respects of improved adhesion to substrate and low preparing temperature.Theyexhibited good wear resistance and high hardness up to 2200 kg/mm~2.Some industrialapplications have been reported.     

X-ray microbeam transmission/fluorescence method for non-destructive characterization of tungsten coated carbon materials

Tungsten erosion, its subsequent transport and redeposition are of great interest, because a full tungsten divertor is foreseen to be used during the deuterium–tritium operational phase of ITER. The erosion of tungsten and carbon marker layers was extensively studied in the outer divertor of ASDEX Upgrade (AUG), and work is currently in progress to completely replace the existing JET CFC tiles with tungsten-coated tiles within the JET ITER-like wall project. The need for fast and non-destructive method which allows the quantitative determination of the thickness of a tungsten coating on a carbon material on large areas led us to evaluate a combined absorption/fluorescence X-ray (XRTF) technique. The method can provide fast analysis, high spatial resolution and a material selective detection of deposited layers and inclusions. It was applied on W coated fine grain graphite (FGG) tiles from AUG's divertor. It is proved that the method is able to provide information about the uniformity of the tungsten coating on a graphite or CFC substrate whilst the technique can be used to determine the thickness of the tungsten and other marker materials coatings. It represents a unique instrument for the post-mortem analysis of the coatings.     

The Effect of the Charge Fluctuation of Dust Parti-cles on Ion-acoustic Wave Excited Through Ionization Instability

The effect of the charge fluctuation of dust particles on ion acoustic wave (IAW) excited through ionization instability was investigated. The hydrodynamic equations and linear time-dependent perturbation theory served as the starting point of theory, by which the dispersion relation and growth rate of the IAW were given. By comparing the results with the case of constant dust charges, it was found that the charge fluctuation of dust particles reduces the instability of the wave mode.     

Influence functions, integral formulas, and explicit solutions for thermoelastic spherical wedges

In this study, new exact Green’s functions and a new exact Green-type integral formula for a boundary value problem (BVP) in thermoelasticity for some spherical wedges with mixed homogeneous mechanical boundary conditions are derived. The thermoelastic displacements are subjected to a heat source applied in the inner points of the spherical wedges and to a mixed non-homogeneous boundary heat conditions. When the thermoelastic Green’s function is derived, the thermoelastic displacements are generated by an inner unit point heat source, described by Dirac’s δ-function. All results are obtained in elementary functions that are formulated in a special theorem. Exact solutions in elementary functions for two particular BVPs of thermoelasticity for spherical wedges also are included. In these particular BVPs, the thermoelastic displacements are subjected to a constant temperature (in the first particular BVP) or to a constant heat source (in the second particular BVP). In both BVPs, the constant temperature or the constant heat source is given on the segment of the radius of the quarter-space. On the boundary half-planes of the quarter-space zero temperature and zero heat flux are prescribed.     

金属及合金中射程参数的研究SCIEI

本文应用金属中Wigner-Sietz(W-S)半径数据和引入等效电荷概念,结合Ziegler的质子注入数据,导出了计算重离子注入各种金属中的电子阻止本领S_c(E)的公式,计算结果与文献中的实测值结果甚为一致。同样,应用合金中的W-S半径,导出了适用于合金硼化物和CsCl型合金的S_c(E)计算公式。计算结果表明,公式对单硼或二硼化合物符合得较好,而对一些复杂结构的合金以及Cr_5B_3和W_2B_5是不适合的。对CsCl型合金,S_c(E)对Bragg定律的偏离系数γ和合金中电荷转移量成正比,后者越大表明金属键越强,则合金对离子的阻止本领越大,这与实验结果是吻合的。合金中两元素在同一周期中位置相差越远,这种趋势越明显。不同周期元素组成的合金更加强了这种趋势。     

Vibration of circular plate with multiple eccentric circular perforations by the Rayleigh-Ritz method

The free vibration of a circular plate with multiple perforations is analyzed by using the Rayleigh-Ritz method. Admissible functions are assumed to be separable functions of radial and tangential coordinates. Trigonometric functions are assumed in the circumferential direction. The radial shape functions are the boundary characteristic orthogonal polynomials generated following the Gram-Schmidt recurrence scheme. The assumed functions are used to estimate the kinetic and the potential energies of the plate depending on the number and the position of the perforations. The eigenvalues, representing the dimensionless natural frequencies, are compared with the results obtained using Bessel functions, where the exact solution is available. Moreover, the eigenvectors, which are the unknown coefficients of the Rayleigh-Ritz method, are used to present the mode shapes of the plate. To validate the analytical results of the plates with multiple perforations, experimental investigations are also performed. Two unique case studies that are not addressed in the existing literature are considered. The results of the Rayleigh-Ritz method are found to be in good agreement with those from the experiments. Although the method presented can be employed in the vibration analysis of plates with different boundary conditions and shapes of the perforations, circular perforations that are free on the edges are studied in this paper. The results are presented in terms of dimensionless frequencies and mode shapes.     

SEM‐EDX and microftir studies on evaluation of protection capacity of some thin phosphate layers

This article presents the SEM‐EDX and microFTIR study and the corrosion behavior of new five types of phosphated coatings obtained by coprecipitation in acid aqueous medium of some metal cations, pursuing the influence of the addition of other cations and a moderator of precipitation, on the uniformity and compactness of the layers and on the morphology of dendritic structure of Zn(II) and Fe(II) phosphates. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.