The application of new nanocomposites: Enhancement effect of polylactide nanofibers/nano-TiO2 blends on biorecognition of anticancer drug daunorubicin

In this contribution, the blending of nano-titanium dioxide (TiO₂) and polylactide (PLA) nanofibers has been adopted as a new nanomaterial to facilitate the biorecognition of an anticancer drug daunorubicin. Our observations demonstrate that upon application of the nano-TiO₂-PLA polymer nanocomposites, the drug molecules could be readily self-assembled on the surface of the new nanocomposites so that considerably enhanced detection sensitivity for the DNA binding behavior could be observed for the relative biorecognition. These results may also imply some potential valuable application of the blending of nano-TiO₂ and PLA nanofibers as a kind of drug carriers in view of the respective good biocompatibility and large surface area of the new nanocomposites.     

Determination of defects in 6H-SiC single crystals irradiated with 20 MeV Au ions

In this paper, the determination of the defects induced by 20 MeV Au irradiations in hexagonal silicon carbide single crystals is discussed. The evolution of the irradiation-induced defects as a function of the ion fluence has been studied as a function of depth below the surface using 0.5-25 keV positron beam based Doppler annihilation-ray broadening spectrometry. Results show the detection of two different kinds of defects, depending on the ion fluence.     

Fock space for fermion-like lattices and the linear Glauber model

The concept of Fock space representation is developed to deal with stochastic spin lattices written in terms of fermion operators. A density operator is introduced in order to follow in parallel the developments of the case of bosons in the literature. Some general conceptual quantities for spin lattices are then derived, including the notion of generating function and path integral via Grassmann variables. The formalism is used to derive the Liouvillian of the d-dimensional Linear Glauber dynamics in the Fock-space representation. Then the time evolution equations for the magnetization and the two-point correlation function are derived in terms of the number operator.     

Surface acoustic waves in interaction with a dislocation

A surface acoustic wave can interact with dislocations that are close to the surface. We characterize this interaction and its manifestations as scattered surface acoustic waves for different orientations with respect to the surface of an edge dislocation. For dislocations that are parallel or perpendicular to the free surface, we present an analytical result for short dislocations with respect to the wave-length that reproduce qualitatively the main features observed for dislocations of various sizes.     

Effect of dielectric barrier discharge on semiconductor Si electrode surface

Electrode materials and shapes affected the discharge modes. Meanwhile, the discharge has influence upon electrode surface. In order to study the effect of discharge on semiconductor electrode, the experiments were carried out using single crystal Si wafer as high voltage electrode of atmospheric pressure dielectric barrier discharge in air. The effects of dielectric barrier discharge on Si electrode surface are analyzed by means of field emission scanning electron microscope (FESEM) and X-ray photoelectron spectroscopy (XPS). The results show that surface roughness and oxidation increase with discharge time, while surface nitridation is not observed on Si electrode surface. It is different from Cu electrode. The difference is due to different chemical reactions between electrode surface and air plasma but could also be ascribed to the different analysis techniques used.     

Surface roughening in Si1−xGex alloy films by 100 MeV Au: Composition dependency

Using a 100 MeV Au beam, the surface roughening kinetics of relaxed Si_1−xGe_x alloy films for x=0.5 and 0.7 are studied by means of ex-situ atomic force microscopy (AFM). Swift heavy ion (SHI) irradiation induced surface roughening behavior is demonstrated using the trend in variation of β as a function of fluence when the data are analyzed in terms of the Edwards-Wilkinson (EW) model. By employing the EW model, the observed surface roughening is explained on the basis of the competition between SHI induced sputtering and smoothening through redeposition of the sputtered atoms. The composition dependent variation of surface morphology with increasing fluence is discussed in the light of the strain distribution along the sample surface.     

Pressure and the quadratic temperature term in the electrical resistance of NbTi

We have measured the electrical resistance of an Nb_0.53Ti_0.47 alloy sample as a function of temperature T (4-300 K) and pressure (<20 GPa). At low temperatures, above the superconducting transition, we observe a T² term whose coefficient decreases with pressure. It is linearly dependent on the residual resistance, that also decreases with pressure, in strong agreement with a Koshino-Taylor origin, i.e. inelastic carrier scattering against impurities.     

Liquid-gas binodal anomaly for systems with pairing transition

For fermionic model systems with a separable interaction the BCS equations are solved self-consistently. In addition, the possibility of a liquid-gas phase transition is considered by inspecting thermodynamic stability. Different examples of temperature-density phase diagrams are given depending on the parameters of a model interaction. In particular, a liquid-gas binodal anomaly is found due to the superposition of the superfluid and the liquid-gas phase transition. Received: 14 October 1997 / Accepted: 2 December 1997     

Hybrid ferromagnetic/semiconductor heterostructures for spintronics

Heterostructures that integrate conventional semiconductors with ferromagnetic semiconductors and ferromagnetic metals are important for developing a framework for semiconductor spintronics. We describe recent efforts to study ‘hybrid’ ferromagnetic/semiconductor heterostructures that combine conventional III-V and II-VI semiconductors with the ferromagnetic semiconductor (Ga,Mn)As and the ferromagnetic metal MnAs. We focus on the characteristics of two novel classes of heterostructures: (a) (Ga,Mn)As/AlAs/MnAs magnetic tunnel junctions (MTJs) that provide an all-electrical scheme for probing spin injection from metals into GaAs and (b) n-ZnSe/(Ga,Mn)As heterojunction diodes that surprisingly exhibit a magnetically-driven photoconductivity.     

Enhancement of L10 ordered FePt by Pt buffer layer

L₁₀-ordered FePt thin films prepared by molecular-beam epitaxy on MgO (0 0 1) substrate at 320 °C with different thickness of Pt buffer layer have been investigated. The out-of-plane coercivity increases with increasing thickness of Pt buffer. The maximum values of the long-range order parameter and uniaxial magnetic anisotropy energy are 0.72 and 1.78×10⁷ erg/cm³, respectively, for films with 12 nm thick Pt buffer layer, where the c/a ratio (0.976) shows the minimum value. The reason for the enhancement in ordering is due to the proper lattice strains Pt buffer bestows on FePt layer, these strains are equal to the contraction in lattice parameter c and the expansion in a. Studies of angular-dependent coercivity revealed that the magnetization reversal behaviour shifts from a domain-wall motion dominated case towards a near rotational mode with increasing thickness of Pt buffer layer.