Chemical etching of a GaSb crystal incorporated with Mn grown by the Bridgman method under microgravity conditions

A GaSb crystal incorporated with Mn has been grown by the Bridgman method on the Polizon facility onboard the FOTON-M3 spacecraft. Structural defects and growth striations have been successfully revealed by the chemical etching method. By calculating various parameters of the convection, the striation patterns can be explained, and the critical value of the Taylor number, which characterizes the convective condition of the rotating magnetic field induced azimuthal flow, was shown. The stresses generated during crystal growth can be reflected by the observations of etch pit distribution and other structural defects. Suggestions for improving the space experiment to improve the quality of the crystal are given.

800nm Semiconductor Absorber with Low Temperature Method and Surface State Method Combined Absorber for Kerr Lens Modelocking of Ti∶Al2O3 Laser

A novel 800nm Bragg mirror type of semiconductor saturable absorption mirror with low temperature method and surface state method combined absorber is presented.With which passive Kerr lens mode locking of Ti∶Al2O3 laser pumped by argon ion laser is realized,which produces pulses as short as 40fs.The spectrum bandwidth is 56nm,which means that it can support the modelocking of 20fs.The pulse frequency is 97.5MHz;average output power is 300mW at the pump power of 4.45W.

Choice of calibration equations of the TSM method

For the reciprocal-test fixtures, there are six independent S-parameters to. be determined, and the thru-short-match (TSM) calibration can provide eight calibration equations. In this paper, the relation of calibration equations is investigated. It has been shown that the four equations obtained from the measurement with a transmission standard can be used simultaneously in the calibration. Experimental results show that the different choice of equations will lead to quite different solution, and the calibration accuracy can be improved by taking advantages of the established relation among the calibration equations and properly choosing calibration equations.

Correlation between Er3+ emission and the microstructure of a-SiOx : H < Er > films

Photoluminescence (PL) from Er-implanted hydrogenated amorphous silicon suboxide (a-SiOX:H(x<2.0)) films was measured. Two luminescence bands with maxima at lambda congruent to 750 nm and lambda congruent to 1.54mum, ascribed to the a-SiOX:H intrinsic emission and Er3+ emission, were observed. Peak intensities of the two bands follow the same trend as a function of annealing temperature from 300 to 1000degreesC. Micro-Raman results indicate that the a-SiOX:H films are a mixture of two phases, an amorphous SiOX matrix and amorphous silicon (a-Si) domains embedded there in. FTIR spectra confirm that hydrogen effusion from a-SiOX:H films occurs during annealing. Hydrogen effusion leads to a reconstruction of the microstructure of a-Si domains, thus having a strong influence on Er3+ emission. Our study emphasizes the role of a-Si domains on Er3+ emission in a-SiOX:H films.

Advanced superconducting electron cyclotron resonance ion source SECRAL: Design, construction, and the first test result

Superconducting electron cyclotron resonance (ECR) ion source with advanced design in Lanzhou (SECRAL) is a next generation ECR ion source and aims for developing a very compact superconducting ECR ion source with a structure and high performances for highly charged ion-beam production. The ion source was designed to be operated at 18 GHz at initial operation and finally will be extended to 28 GHz. The superconducting magnet confinement configuration of the ion source consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamping. At full excitation, this magnet assembly can produce peak mirror fields on the axis of 3.6 T at injection, 2.2 T at extraction, and a radial sextupole field of 2.0 T at plasma chamber wall. What is different from the traditional design, such as LBNL VENUS and LNS SERSE, is that the three axial solenoid coils are located inside of the sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. SECRAL may open the way for building a compact and high-performance 18-28 GHz superconducting ECR ion source. Very preliminary commissioning results are promising. Detailed design, construction issues and very preliminary test results of the ion source at 18 GHz are presented.

Scaling and the thermal conductivity of the Frenkel-Kontorova model

We have studied the dependence of the thermal conductivity kappa on the strength of the interparticle potential lambda and the strength of the external potential beta in the Frenkel-Kontorova model. We found that the functional relation can be expressed in a scaling form, kappa(proportional to) lambda 3/2/beta(2 center dot). This result is first obtained by nonequilibrium molecular dynamics. It is then confirmed by two analytical methods, the self-consistent phonon theory and the self-consistent stochastic reservoirs method. The thermal conductivity kappa is therefore a decreasing functon of beta and an increasing function of lambda.

Measurement of neutron-removal cross section of neutron-rich nucleus He-8 by using the transmission method

The neutron-rich nucleus He-8 is selected by RIBLL from the breakup of 50MeV/u C-13 on be target at HIRFL. The 2n-removal and 4n-removal cross section of He-8 was measured by using the transmission method. The point that He-4 is He-8 core can be reduced from the experiment data via the Ogawa's theory.

Determination of urinary oxidative DNA damage marker 8-hydroxy-2 '-deoxyguanosine and the association with cigarette smoking

8-hydroxy-2'-deoxyguanosine (8OHdG) has been widely used as a biomarker of oxidative DNA damage in both animal models and human studies. To evaluate the effect of cigarette smoking on oxidative stress, we studied the levels of urinary 8OHdG from smokers and non-smokers and investigated the association with cigarette smoking. The urinary 8OHdG concentrations were determinated by capillary electrophoresis with end-column amprometric detection (CE-AD) after a single-step solid phase extraction (SPE), and then quantitatively expressed as a function of creatinine excretion. To increase the concentration sensitivity, a dynamic pH junction was used and the focusing effect was obvious when using 30 mM phosphate (pH 6.50) as sample matrix. The limit of detection is 4.3 nM (signal-to-noise ratio S/N = 3). The relative standard deviation (R.S.D.) was 1.1% for peak current, and 2.3% for migration time. Based on the selected CE-AD method, it was found that the mean value of urinary 8OHdG levels in the smokers significantly higher than that in non-smokers (31.4 +/- 18.9 nM versus 14.4 +/- 7.6 nM, P = 0.0004; 23.5 +/- 21.3 mug g(-1) creatinine versus 12.6 +/- 13.2 mug g(-1) creatinine, P = 0.028). (C) 2004 Elsevier B.V. All rights reserved.

Excretion pattern investigation of urinary normal and modified nucleosides of breast cancer patients by RP-HPLC and factor analysis method

Modified nucleosides, formed post-transcriptionally in RNA by a number of modification enzymes, are excreted in abnormal levels in the urine of patients with malignant tumors. To test their usefulness as tumor markers, and to compare them with the conventional tumor markers, a reversed-phase high-performance liquid chromatographic (RP-HPLC) method and a factor analysis method have been used to study the excretion pattern of nucleosides of breast cancer patients. A clear cut differentiation of the breast cancer group and the healthy individuals in two clusters without overlapping was obtained. Copyright (C) 2000 John Wiley & Sons, Ltd.

Enhancements of the simulation method on the edge effect in resin transfer molding processes

In resin transfer molding processes, small clearances exist between the fiber preform and the mold edges, which result in a preferential resin flow in the edge channel and then disrupt the flow patterns during the mold filling stage. A mathematical model including the effect of cavity thickness on resin flow was developed for flow behavior involving the interface between an edge channel and a porous medium. According to the mathematical analysis of momentum equations in a fully developed rectangular duct and formulations of the equivalent edge permeability, comparing with three-dimensional Navier-Stokes equations, the governing equations were modified in the edge channel. The volume of fluid (VOF) method was applied to track the flow front. A simple case is numerically simulated using the modified governing equations. The effects of edge channel width and cavity thickness on flow front and inlet pressure are analyzed, and the evolution characteristics of simulated results are in agreement with the experimental results. (c) 2007 Elsevier B.V. All rights reserved

Surface modification of bioactive glass nanoparticles and the mechanical and biological properties of poly(L-lactide) composites

Novel bioactive glass (13G) nanoparticles/poly(L-lactide) (PLLA) composites were prepared as promising bone-repairing materials. The BG nanoparticles (Si:P:Ca = 29:13:58 weight ratio) of about 40 run diameter were prepared via the sol-gel method. In order to improve the phase compatibility between the polymer and the inorganic phase, PLLA (M-n = 9700 Da) was linked to the surface of the BG particles by diisocyanate. The grafting ratio of PLLA was in the vicinity of 20 wt.%. The grafting modification could improve the tensile strength, tensile modulus and impact energy of the composites by increasing the phase compatibility.

Interfacial behavior of primary amine N1923 and the kinetics of thorium(IV) extraction in sulfate media

The influences of additive, diluents, temperature, acidity of the aqueous phase on the interfacial behavior of primary amine N1923 in sulfate media have been investigated using the Du Nouy ring method. In addition, the effect of concentration of thorium(IV) loaded in the organic phase on the interfacial tension has also been studied. The interfacial tension isotherms are processed by matching different adsorption equations such as the Gibbs and the Szyszkowski. The surface excess at the saturated interface (Gamma (max)) and the minimum bulk concentration of the extractant necessary to saturate the interface (C-min) under different conditions are calculated according to two adsorption equations to be presented in comprehensive tables and figures. It appears that primary amine N1923 has strong interfacial activity and behaves very differently in various diluents systems. The surface excess at saturated interface increase with the type of diluerits in the following order: chloroform < aromatic hydrocarbons < aliphatic hydrocarbons. The relationship between the interfacial activity and kinetics of thorium extraction by primary amine N1923 has been discussed by considering different factors. However, the interfacial activity of primary amine N1923 is only a qualitative parameter suggesting the interfacial mechanism for thorium extraction, it cannot give strong evidence quantitatively supporting this mechanism.

Composites of poly(lactide-co-glycolide) and the surface modified carbonated hydroxyapatite nanoparticles

To improve the mechanical properties of the composites of poly(lactide-co-glycolide) (PLGA, LA/GA = 80/20) and the carbonate hydroxyapatite (CHAP) particles, the rice-form or claviform CHAP particles with 30-40 nm in diameter and 100-200 nm in length were prepared by precipitation method. The uncalcined CHAP particles have a coarse surface with a lot of global protuberances, which could be in favor of the interaction of the matrix polymer to the CHAP particles. The nanocomposites of PLGA and surface grafted CHAP particles (g-CHAP) were prepared by solution mixing method. The structure and properties of the composites were subsequently investigated by the emission scanning electron microscopy, the tensile strength testing, and the cell culture. When the contents of g-CHAP were in the range of 2-15 wt %, the PLGA/g-CHAP nanocomposites exhibited an improved elongation at break and tensile strength. At the 2 wt % content of g-CHAP, the fracture strain was increased to 20%) from 4-5% for neat PLGA samples. Especially at g-CHAP content of 15 wt %, the tensile strength of PLGA/g-CHAP composite was about 20% higher than that of neat PLGA materials. The tensile moduli of composites were increased with the increasing of filler contents, so that the g-CHAP particles had both reinforcing and toughening effects on the PLGA composites. The results of biocompatibility test showed that the higher g-CHAP contents in PLGA composite facilitated the adhesion and proliferation properties of osteoblasts on the PLGA/g-CHAP composite film.

Interfacial behavior of DEHEHP and the kinetics of cerium(IV) extraction in nitrate media

The effects of diluents, temperature, acidity, and ionic strength of the aqueous phase on the interfacial properties of DEHEHP have been extensively investigated using the Du Nouy ring method. In addition, the effect of cerium(IV) concentration loaded in the organic phase on the interfacial tension has also been studied. With the increase of DEHEHP concentration, the value of interfacial tension (gamma) decreases in the studied system, which shows that DEHEHP has interfacial activity as a kind of surfactant. The surface excess at the saturated interface (Gamma(max)) and the minimum bulk concentration of the extractant necessary to saturate the interface (C-min) under the different conditions are calculated according to two adsorption equations such as the Gibbs and Szyszkowski functions to be presented in comprehensive tables and figures. The relationship between the interfacial activity of DEHEHP and cerium(IV) extraction kinetics by DEHEHP has been discussed by considering different factors such as the effects of diluents and temperature. However, the interfacial activity parameter of extractant only is a qualitative parameter, but cannot provide strong enough evidence to quantitatively explain the relationship between extraction kinetics and interfacial properties of an extractant.

Effective descriptions of molecular structures and the quantitative structure - Activity relationship studies

In this research. we found CoMFA alone could not obtain sufficiently a strong equation to allow confident prediction for aminobenzenes. When some other parameter. such as heat of molecular formation of the compounds, was introduced into the CoMFA model, the results Were improved greatly. It gives us a hint that a better description for molecular structures will yield a better prediction model, and this hint challenged us to look for another method-the projection areas of molecules in 3D space for 3D-QSAR. It is surprising that much better results than that obtained by using CoMFA Were achieved. Besides the CoMFA analysis. multiregression analysis and neural network methods for building the models were used in this paper.