Search

Abstract: Nanomaterials are attracting a great deal of attention as potentially excellent transporters of peptides, proteins, genes, and drug medications; however, thus far many nanomaterials are toxic in vivo. The nanotubes utilized in the system described herein were controlled so as not to exhibit toxicity, due to their extremely small dimensions and the constituent material itself. A drug delivery system using silica coated titania nanotube–protein conjugations was applied to mouse neural stem cells (m-NSCs) and cultured for one month. Nanotubes were prepared by silica sol–gel treatment and bonded with proteins by an electrical charge and were readily detached from proteins in cytoplasm. The delivered proteins evidenced functions in live cells for transcriptional factors; the morphology of the cells was consequently altered. In this study, we demonstrate the ability of this nano-sized material to deliver peptides, proteins, and drugs, and also show that the delivered proteins continued to function in live cells. [Copyright &y& Elsevier]

Abstract: Epitaxial MgFe2O4 (MFO) thin films have been deposited on SrTiO3 (STO) (100) substrates via a pulsed laser deposition technique under different oxygen partial pressures at 650°C. The various oxygen partial pressures showed significant influence on the sticking coefficient and the spatial distribution of target materials. The lattice constant of the MFO thin films was decreased with increasing an oxygen partial pressure. The thin films synthesized at high oxygen partial pressure showed rough surface morphology. Also, epitaxial MFO thin films showed anisotropic magnetic behavior and the film grown at the oxygen pressure of 40mTorr exhibited the highest saturation magnetization of 194emu/cc. [Copyright &y& Elsevier]

Abstract: The effects of Fe doping on phase stability and electrical conductivity were investigated for the 25mol% Sr and 20mol% Mg-doped lanthanum gallates (LSGM-2520). While secondary phases, in addition to perovskite phase, were formed for an undoped LSGM-2520 in accordance with previous reports, a single phase perovskite phase was obtained by addition of a small amount (∼4mol%) of Fe to LSGM-2520. The conductivity of 4mol% Fe-doped LSGM-2520 was as high as 0.17Scm−1 at 800°C and it was confirmed to be ionic based on its dependency on oxygen partial pressures. Crystallographic analysis using neutron diffraction and electron diffraction determined the crystal structure and lattice parameters for 4mol% Fe-doped LSGM-2520. [Copyright &y& Elsevier]

Abstract: A mixed cathode material between Li2MnO3 and Li[Mn1/3Ni1/3Co1/3]O2 for high capacity lithium secondary batteries was introduced in this study. It was prepared using the sucrose combustion process because this is a simple process. The oxidation states of Mn, Co and Ni ions in the pristine Li[Li(1−x)/3Mn(2−x)/3Ni x/3Co x/3]O2 compounds were confirmed to be tetravalent, trivalent and divalent, respectively, via XANES measurements. Electrochemical charge/discharge studies showed that the highest first discharge capacity of 224mAh/g was obtained in composition of x =0.5 at a 0.2C rate. The oxidation state of the Co and Ni ions in the Li[Li1/6Mn1/2Ni1/6Co1/6]O2 changed to higher oxidation states, but that of the Mn ions did not change. [Copyright &y& Elsevier]

Abstract: Nanostructured semiconducting metal-oxides and particularly one-dimensional nanotube devices offer enhanced energy conversion efficiencies in dye-sensitized solar cells (DSSCs). To absorb a sufficient light, the thickness and surface area of TiO2 photoelectrode are important. We focus on the preparation of transparent TiO2 nanotube photoelectrode grown perpendicularly on a conductive glass substrate. For growing nanotube array using anodization method, deposition of high-quality titanium is needed. We could obtain relatively longer 680-nm-thick TiO2 nanotube arrays in glycerol-based electrolyte than those of others result (⩽360nm). After crystallization, the nanotube arrays were treated with TiCl4 to enhance the photogenerated current and then integrated into the DSSC structure using a N3 ruthenium-based dye. The DSSC using TiCl4-treated TiO2 nanotube exhibited a conversion efficiency of 0.31% under 100mV/cm2 (AM 1.5) illumination. [Copyright &y& Elsevier]

Abstract: We report on the dielectric properties and leakage current characteristics of 3 mol% Mn-doped Ba0.6Sr0.4TiO3 (BST) thin films post-annealed up to 600 °C following room temperature deposition. The suitability of 3 mol% Mn-doped BST films as gate insulators for low voltage ZnO thin film transistors (TFTs) is investigated. The dielectric constant of 3 mol% Mn-doped BST films increased from 24 at in-situ deposition up to 260 at an annealing temperature of 600 °C due to increased crystallinity and the formation of perovskite phase. The measured leakage current density of 3 mol% Mn-doped BST films remained on the order of 5×10−9 to 10−8 A/cm2 without further reduction as the annealing temperature increased, thereby demonstrating significant improvement in the leakage current characteristics of in-situ grown Mn-doped BST films as compared to that (5×10−4 A/cm2 at 5 V) of pure BST films. All room temperature processed ZnO–TFTs using a 3 mol% Mn-doped BST gate insulator exhibited a field effect mobility of 1.0 cm2/Vs and low voltage device performance of less than 7 V. [Copyright &y& Elsevier]

Abstract: We reported the Ag adding effects on the crystallization behavior in Ge2Sb2Te5 film. Ag x (Ge2Sb2Te5)1− x films (where x =0–0.2) were deposited on SiO2 wafer and glass substrate by RF magnetron co-sputtering and annealed by RTA (rapid thermal annealing) at various temperature to crystallize. The effects of Ag adding on the structural, thermal and electrical properties were measured by X-ray diffraction, X-ray reflectivity, AFM, SEM, DSC and 4-point probe analysis. It was found that the crystallization temperature increased by Ag adding in Ge2Sb2Te5 films. However, the surface of Ag x (Ge2Sb2Te5)1− x films got rough when annealing temperature and Ag contents increased. According to the Kissinger method, the activation energy for crystallization increased as the Ag content increased. It is thought that Ag atoms in Ge2Sb2Te5 act as an amorphous stabilizer and they make it hard to switch from amorphous to crystalline phase. From this study, we would show the Ag0.06(Ge2Sb2Te5)0.94 film is suitable for phase change memory material because of its higher crystallization temperature and structural stability. [Copyright &y& Elsevier]

In this paper, Au/Ba0.6Sr0.4TiO3 (BST) ferroelectric thin-film interdigital capacitors on MgO substrate are presented. The interdigital capacitors with a 50-μm gap and different doped materials of BST thin film are characterized. Tunability rates of 11.2% and 28% are obtained for the undoped BST thin film and the Mn-doped (3 mol %) BST thin film, respectively, at 3.5 GHz with a bias voltage of 20 V. Furthermore, the loss tangent of the BST thin film is found to be approximately 0.0158 and it decreases with Mn doping. Mn-doped (3 mol %) BST film is suggested to be an effective candidate for high-performance tunable device applications. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 15–18, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20709 [ABSTRACT FROM AUTHOR]

LiCoO2 thin films have received attention as cathodes of thin-film microbatteries in these days. In this study, LiCoO2 thin films were fabricated by a sol–gel spin coating method and an annealing process. They were deposited on Pt(111) and Pt(200) substrates to investigate the effect of orientation of current collector. The crystallinity, microstructure and electrochemical properties of final films are also studied by XRD, SEM and galvanostatic charge/discharge cycling test. Films heat-treated under appropriate conditions exhibit high capacity and good crystallinity so those films are considered to be candidates as cathodes for thin-film microbatteries. [Copyright &y& Elsevier]

Electrochemically active lithium nickel cobalt oxide thin-film has not been fabricated until now. To fabricate stoichiometric lithium nickel cobaltate films, a sputtering target of proper composition has been synthesized via a solid-state reaction. The films are deposited by RF magnetron sputtering at room temperature. As-deposited films show an amorphous structure. By varying the deposition conditions—such as the working pressures and deposition times—thin-films with different characteristics are produced. The relationship between physical characteristics and electrochemical properties is investigated. A crystallized thin-film prepared by an annealing method displays a good discharge capacity and cycle life. [Copyright &y& Elsevier]

Close packed arrays of hollow SnO2hemispheres were prepared using PMMA microspheres as sacrificial templates for subsequent sputter-deposition of SnO2films, leading to a threefold enhancement in gas sensitivity compared to non-templated (flat) films. [ABSTRACT FROM AUTHOR]

Highly ordered TiO2 nanotube arrays were prepared by anodic oxidation of Ti foil in an application to dye-sensitized solar cells (DSCs). A fullerene derivative called PC61BM was used as a material for the surface modification of TiO2 nanotube arrays to improve the power conversion efficiency of DSCs Although open circuit voltages (Voc) were slightly decreased by PC61BM interlayer, short circuit current densities (Jsc) were increased and thus the power conversion efficiencies were improved. EIS (Electrochemical Impedance Spectroscopy) results showed superior properties for PC61BM-coated samples.

Single-phase BiFeO3 powder was successively synthesized by a low-temperature hydrothermal method. Scanning electron microscopy and transmission electron microscopy results showed that BiFeO3 powder had several hundred nanometers to micrometer-sized particles with a broad size distribution. BiFeO3 powder showed weak-ferromagnetic behavior with a small magnetization value (Ms approximately 20 memu/g) at room temperature. Rietveld refinement results for the crystal structure show the displacive disorder of the Fe-site(6a); the Fe-site(6a) splits into two pairs, Fe(1) and Fe(2) displaced by 0.9 angstroms from each other and these sites are partially occupied. Hence the O-site(18b) also splits into the two partially occupied sites forming a distorted FeO6 octahedras. The weak ferromagnetism observed in the hydrothermal BFO powder is ascribed to the displacive disorder of FeO6 octahedras resulting in an incomplete counterbalance between the antiferromagnetic sublattices of the Fe-ions.

In this paper, a Ba0.6Sr0.4TiO3 (BST) tunable phase shifter with TiO2 films as microwave buffer layer between BST and silicon (Si) substrates is presented. The TiO2 buffer layer is grown by atomic layer deposition (ALD) onto Si substrate followed by pulsed laser deposition (PLD) of BST thin films onto the TiO2 buffer layer. The phase shifter fabricated on BST films grown on TiO2/Si substrate shows a good figure of merit (FOM) of 75.4 degrees/dB by exhibiting improved tunablity while retaining an appropriate dielectric Q as compared to 55.1 degrees/dB of BST/MgO structure. The TiO2 buffer layer grown by ALD enables successful integration of BST-based microwave tunable devices with high resistive Si wafer.

Water structure around hydrophilic adsorbents is expected to differ from normal water structure. In some cases, a change of water structure seems to significantly affect phenomena involved in water-adsorbent systems. To investigate this, we have performed molecular dynamic simulations of three systems, water between (111) surfaces of Pt, water between (100) surfaces of Pt, and pure water at 298 K. For the analysis of water structure, we concentrated on the five-membered ring (R5) structure and six-membered ring (R6) structure, which are the most probable in nature. For both (111) and (100) of Pt, the ratio of hexameric ring/pentameric ring (R6/R5) in semibound regions was higher than that of bulk water, as expected. The function of adsorbent ceramics was explained in terms of the change of water structure when they are used as biomaterials, support materials, etc. The obscure mechanisms for the effects of medicine stones, antioxidants, etc., were also discussed from this point of view.