Differential scanning calorimetric (DSC) and X-ray diffraction (XRD) measurements on Sn-Sb-Se glassy semiconductors have been performed. Phase separation has been revealed with the broadening of the exothermic peak for 11 at% of Sn. The X-ray diffraction studies of annealed samples show that the investigated system could be treated as a solid solution of Sb2Se3 and SnSe2 phases. The deconvolution procedure was used to investigate the crystallization mechanism for the broad exothermic peaks in the thermal scans. From the heating rate dependence of the crystallization temperature, the crystallization parameters have been determined using Kissinger equation and Matusita equation. The investigated parameters indicate higher thermal stability and glass forming ability of Sn10Sb20Se70 chalcogenide glass.

This paper presents a review of some investigations that we have performed on electronically controlled EBG structures including their electromagnetic characterization and their applications for adaptive antenna. Firstly, for a structure composed of 2D cylindrical metallic wires array, an equivalent circuit approach is proposed based on a combination between the well-known Marcuvitz model and a distributed impedance per unit length model. The proposed method has allowed the determination of the S parameters for a 2D cylindrical metallic wires array loaded by active elements. The results when using this proposed approach show a good concordance with those obtained using other time consuming methods like a local field approach and the finite element method. Secondly a continuous electronic control for the radiation pattern of an adaptive antenna, using an Electromagnetic Band Gap structure having variable localized elements, is investigated. Rigorous electromagnetic simulations for this structure are carried out using integral equations techniques solved by the method of moments. Measurements of the realized radiating structure are in a very good agreement with simulated results.

P-Aminoazobenzene (PAAB) is one of the 24 kinds of carcinogenic azo dyes that the European Union forbids but it does not yet have an official method to detect PAAB. This paper experimentally observes the Normal Raman Spectrum (NRS) and infrared absorption spectrum of PAAB and presents theoretical vibrational spectra calculated from a density functional theory (DFT) method on the basis of B3LYP with 6–31 basis set. The calculated results show very good agreement with the experimentally observed IR and Raman frequencies. We also report the SERS spectra of PAAB adsorbed on silver and copper layers, which offer a sensitive but simple method to detect PAAB. Finally, the possible adsorbed states of PAAB on the silver and copper layers are discussed.

We investigate the temperature dependence of photoluminescence (PL) properties of InAs/GaAs quantum dot (QD) heterostructures. The temperature dependence of the InAs exciton energy and linewidth is found to display a significant difference due to the different dot size distribution. We propose a model, which takes into account the dot size distribution, state filling effect, carrier thermal escaping and retrapping, and electron-phonon scattering, to explain the carriers transferring mechanisms in the QD system. The experimental results are reproduced well by our model. Sample with lower dot size uniformity reveals evident thermal redistribution effect among dots, but the effect is weak for sample with higher dot size uniformity and is overcome by the electron-phonon scattering, which is consistent with the observed monotonically increasing linewidth of PL spectra with temperature.

Charge retention properties of Ge nanoparticles embedded in SiO2 matrix are investigated. Formation of embedded Ge nanoparticles was accomplished by optimizing electron beam evaporation process. Size of Ge nanoparticles has been characterized by atomic force microscopy (AFM) which comes out to be ~15 nm. Presence of Ge nanoparticles is confirmed by micro-Raman analysis. Memory effect of Ge nanoparticles is verified by capacitance-voltage (C-V) measurements which show hysteresis in the C-V curves.

PVPx V2O5 (x = 0, 0.5 and 1) nanobelts were obtained using a simple hydrothermal process from V2O5 xerogel. The structure and morphology of the samples were characterized by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The interaction between the poly (vinyl pyrrolidone) (PVP) and V2O5 xerogel in the nanocomposites was verified by Fourier transformation infrared spectroscopy (FTIR). The electrochemical cells, with a configuration Li/(LiPF6 + EC + DMC)/(V2O5 + PVP), were fabricated and their electrochemical performance was studied.

We have observed ultraviolet photosensitive properties ofSrTiO3 single crystals. The photoresponse signal reaches 7.6 mVunder a bias voltage of 110 V and an on-sample energy of 250 nJ fora 15-ps-duration 355 nm laser pulse. A linear relationship isobtained to the peak signal as a function of bias without anysaturation trend from 1 to 110 V. Ultrafast characteristic as afunction of time was also presented with the rise time as short as750 ps. Furthermore, a weak photoresponse was detected with a largebias of 2.5 kV under a 420-nm-wavelength laser pulse due to bandedge tilting, and drop three orders of magnitude than that under the355 nm laser pulse, indicating the setup consisting of SrTiO3single crystal is suitable for detecting ultraviolet radiation.

This article presents a group-theoretical investigation of an incommensurate magnetic structure in the case where the crystal structure is centrosymmetric while the structure vector k is not conserved by inversion. A first method starts with the conventional group-theoretical treatment taking into account the transformations which conserve kand then combines the solutions to obtain a centrosymmetric and real magnetization. A second method includes inversion in the group-theoretical treatment, for instance by introducing the complex conjugation operator and corepresentations. The general theory is applied to CeAl2 with the scope of improving the knowledge of its magnetic structure.

We have investigated the existence of any possible pair breaking mechanism in Cu0.5Tl0.5Ba2Ca2Cu0.35Zn2.65O10−δ superconductor by carrying out post-annealing experiments in nitrogen, oxygen and air atmospheres. This material is grown in tetragonal structure with a and c-axes lengths 3.879 Å and 14.581 Å; the c-axis length is found to decrease with the increased concentration of Zn in the final compound. The substitution of Zn at CuO2 planar sites in formula unit Cu0.5Tl0.5Ba2Ca2Cu3−y Zny O10−δ has given superconductivity for all the Zn doping concentration of y = 0.75, 1.5, 2.25, 2.5, 2.65. The zero resistivity critical temperature [T c (R = 0)], the quantity of diamagnetism and critical current [I c (H = 0)]are found to increase with increased Zn doping. In Zn doped samples, post-annealing in air has given a maximum increase in superconducting properties, which showed that final material is optimally doped with carriers in ZnO2 planes. Since the superconducting properties are marginally suppressed in Zn doped samples by post annealing in O2 and N2 atmospheres, it has lead to a definite conclusion that pair breaking mechanism, suggested in previous studies, are absent altogether in our Cu0.5Tl0.5Ba2Ca2Cu0.35Zn2.65O10−δ superconductor. The synthesis of Cu0.5Tl0.5Ba2Ca2Zn3O10−δ superconductor by this method is extremely reproducible.

Mechanical Q-factor measurements of single crystalline calcium fluoride CaF2 bulk material are presented. Resonant modes between 27 and 100 kHz were investigated on a cylindrical test sample ( $\varnothing$ $75~{\rm mm} \times 75~{\rm mm}$ ). For selected modes low temperature measurements of the mechanical Q-factor were done within a temperature range from 5 to 300 K. For the Q-measurements a ring-down technique was used. The substrate was suspended as a pendulum by means of a tungsten wire loop. The highest Q-factor has been achieved around 60 K with 3 × 108 which is the highest Q-factor reported on CaF2 up to now.

This paper presents the application of the Finite Element Method FEM to the resolution of system Helmholtz coupled equations that has been obtained in the coaxial waveguides containing magnetic anisotropic materials with loss. This application is based on variational method which necessitates the construction of functional stationary written in the form of integral equation and dependent on the electromagnetic fields. After being minimized, this functional leads to algebraic equation system to which we can apply many numerical resolution algorithms. The electromagnetic study of the waveguide led us to a system of Helmholtz coupled equations which is difficult to be solved analytically. Our software code allows us to determine the electromagnetic field distribution in all points of the coaxial waveguide. The result has been validated when the coaxial waveguide was entirely loaded with air. This software has later been applied when the waveguide was partially filled with a magnetic anisotropic material with loss ( $\varepsilon_r$ ,  $\overline{\overline{\mu_r}}$ ).

Coating of Ti-6Al-4V alloy substrates with TiN/Ti multi-layered films by magnetron sputtering in Ar gas atmosphere was examined, aiming at the application of the alloy to artificial heart valves, in order to improve not only the adhesion between the deposited film and the alloy but also the surface smoothness of titanium nitride coatings and thereby to improve the blood compatibility as well as the biocompatibility of the alloy coated with the titanium nitride film. The effects of the thickness of the TiN (titanium nitride) layer on the surface morphology of the film were investigated, in order to develop TiN coatings with higher blood compatibility. The multi-layered films were deposited by sputtering in sequence pure titanium and titanium nitride targets. The thickness of titanium nitride layer was varied from 300 nm to 800 nm, while that of pure titanium was constantly 200 nm. Under visual observation, the obtained multi-layered films looked yellow gold and appeared to be uniform and adhesive, while TiN monolithic films deposited directly onto the alloy substrate under the same sputtering conditions peeled off partly. Therefore it was found that the multi-layered thin films were more adhesive to the alloy than the monolithic films. According to AFM (Atomic Force Microscope) images for both of the films, the surface morphology of each TiN layer observed under the scope of nanometer-scaled area was rough with pits and bumps, while that under the scope of micrometer-scaled area was smooth without such pits and bumps. Furthermore based on the AFM, the surface roughness $\sigma_{\it RMS}$ measured under the area of nanometer scale was found to increase with the increase of the thickness of the TiN layer in the multi-layered film, although that measured under the area of micrometer scale was assumed to be independent of the thickness of the TiN layer.

In this paper the breakdown time delay t d in neon was measured and the formative time delay t f determined in three different ways: (1) from the Laue diagrams, by taking the valueswhere linear approximation of experimental data intersects the time axis; (2) from histograms, by taking the minimum values of delay times $t_{d\min}$ for the formative time; and(3) from a difference $t_f= \overline {t_d}- \overline {t_s}\approx \overline {t_d} - \sigma\,(t_d)$ , where standard deviation $\sigma\,(t_d)$ is approximately equal to the mean ofthe statistical time delay $\overline {t_s}$ . The dependency of the formative time delay on working voltages U w was found and fitted by different approximate analytical models. The separationof the formative and statistical time delay distributions was discussed and the distribution of the formative time delay experimentally obtained. The nonstationary exponentialdistributions with time dependent parameters were introduced to describe the statistical time delay distributions under conditions of increased cathode sputtering.

A procedure is presented which allows to compute in anon-invasive manner, blood viscosity through flow measurementsobtained at a fixed vessel cross-section. The data set is made ofmeasurements (artery radius and spatially discrete velocity profiles)performed at given time intervals for which the signal to noise ratiois typical of U.S. Doppler velocimetry in clinical situation. Thisidentification approach is based on the minimization, through abackpropagation algorithm, of a cost function quantifying the distancebetween numerical data obtained through Navier-Stokes simulations andexperimental measurements. Since this cost function implicitlydepends on the value of viscosity used in numerical simulations, itsminimization determines an effective viscosity which is shown to berobust to measurement errors and sampling time. Such an approach isshown to work in an in vitro experiment, and seems to besuitable for in vivo measurements of viscosity by the atraumatictechniques of Doppler echography.

Accepted models of polymers in flow assume that the polymer chains stretch with the elastic energy stored as a reduced entropy of the chain. The first optical measurement of changes in the Polydiacetylene 4-Butoxycarbonylmethylurethane (4-BCMU) polymer Kuhn segment lengths in Couette flow are reported. This polymer in semi-dilute solution shows a reducing conjugated segment length with increasing flow rate. The visco-elasticity for this polymer is attributed to compressive entropy loss in the chain. This is a reversal of the physics assumed in models of polymer flow based on the Kuhn model. The restricted volume of the chain due to the presence of the neighbouring polymers results in compressive hydrodynamic forces on the chains in Couette flow at semi-dilute concentrations.

Numerical solutions of 2-D steady incompressible flowinside a triangular cavity are presented. For the purpose ofcomparing our results with several different triangular cavitystudies with different triangle geometries, a general trianglemapped onto a computational domain is considered. The Navier-Stokesequations in general curvilinear coordinates in streamfunction andvorticity formulation are numerically solved. Using a very fine gridmesh, the triangular cavity flow is solved for high Reynoldsnumbers. The results are compared with the numerical solutions foundin the literature and also with analytical solutions as well.Detailed results are presented.