Masanobu Kusunoki

Nanocapsules incorporating IgG Fc-binding domain derived from Staphylococcus aureus protein A for displaying IgGs on immunosensor chips.

To enhance the sensitivities and antigen-binding capacities of immunosensors, oriented immobilization of antibodies on the surface of the sensor chip is critical, but to date, this has not been adequately achieved. We describe a way of adsorbing immunoglobulin (Ig) proteins onto 32-nm bio-nanocapsules (BNCs) through IgG Fc-binding domains derived from Staphylococcus aureus protein A (ZZ-BNC). This arrangement permits approximately 60 molecules of mouse total IgG bind to ZZ-BNC and all the IgG Fv regions to be displayed outwardly for the effective binding of antigens. ZZ-BNCs adsorbed onto the gold surface of the sensor chip of the quartz crystal microbalance (QCM) could markedly enhance the sensitivity and antigen-binding capacity of the chip. On the sensor chip of surface plasmon resonance (SPR), antibodies on the ZZ-BNCs showed higher affinities to each antigen than those on protein A. The BNC-coated sensor chip is very stable, and should prove useful for various immunosensor applications due to oriented immobilization of antibodies.

High-quality Y-Ba-Cu-O thin films by PLD-ready for market applications

Large-area pulsed laser deposition (PLD) has reached a state in terms of film quality and reproducibility which makes possible now real market applications of PLD-YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films on both sides of R-plane sapphire substrates as HTSC devices in satellite and mobile communication systems. Bandpass filters optimized from PLD-YBCO thin films presently fulfil the requirements of the main national companies which are active in future communication techniques. A relatively simple PLD arrangement with fixed laser plume and rotating substrate, with an offset between the laser plume and the center of the substrate is employed to deposit laterally homogeneous 3-inch diameter Ag-doped YBCO thin films. With the experience of more than 1,000 double-sided 3-inch diam. films a high degree of homogeneity and reproducibility of j/sub c/ and R/sub s/ is reached. The extension up to 8-inch substrate diameter will increase the productivity of the flexible PLD technique considerably.

Effect of deposition rate on the surface morphology of CeO2 films deposited by pulsed laser deposition

Abstract We have investigated the effect of the deposition rate, as a direct function of the laser pulse repetition rate, on the surface morphology of CeO 2 films deposited by the pulsed laser deposition (PLD) technique on r-cut Al 2 O 3 (1102) substrates. The critical thickness is defined as the thickness before the onset of increased growth of large islands and abrupt increase in surface roughening. Two regimes of growth were found within the investigated range of deposition rate. It is found out that in the high deposition rate-regime (within 2–4 nm/min), the critical thickness is ∼90 nm, but in the low deposition rate-regime (less than 1 nm/min), the critical thickness is shifted to ∼40 nm. Films belonging to these two regimes of crystalline growth were found to have characteristically different formations and surface morphologies. As observed through atomic force microscopy (AFM), the surface morphology is composed of longitudinal islands forming a maze-like pattern in the high deposition rate-regime, while the characteristic morphology was composed of rounded islands in the low deposition rate-regime. Significant reduction in the areal density of large islands and characteristically smoother films was achieved using a low deposition rate.

The correlation of the critical current density and surface resistance of YBa2Cu3O7−δ thin films

Abstract We have examined the correlation between the critical current density ( J c ) and the surface resistance ( R s ) of an YBa 2 Cu 3 O 7− δ (YBCO) thin film. YBCO films were prepared in an inductively coupled plasma sputtering system on MgO and BSO/MgO substrates. BaSnO 3 (BSO) was used as a buffer material for the MgO substrates. J c was determined by magnetic measurements, and R s was measured using a sapphire rod resonator method. The correlation of critical current and surface resistance has been reported previously, however, there is few researches in which a systematic correlation of R s and J c using the same sample has been done. To begin with, we measured R s by the dielectric resonator method, and next, J c was measured using the magnetic field method. As a result, it was proven that there was a strong correlation between R s and J c . We found that the relationship between J c and R s (at 22 GHz) could be expressed by the following equation, R s =2.0×10 7 J c −1 , where the unit of R s is the ohm, and the unit of J c is A/m 2 . It was found that the relation was applicable in a wide temperature range under T c . The value of the surface resistance can be estimated, if an accurate critical current is obtained.

The influence of in-plane 0–45° grain boundary on microwave surface resistance of c-axis YBa2Cu3Oy films on MgO substrate

Abstract The effect of in-plane 0–45° grain boundaries on surface resistance ( R s ) of c -axis YBa 2 Cu 3 O y (YBCO) films on MgO substrates is discussed. Samples that have various densities of 45° rotated grains were prepared using a self-template technique. The R s values at 22 GHz were measured by the dielectric resonator method using a cryocooler. The R s systematically changed corresponding to the amount of 0–45° grain boundaries. Conspicuous feature of the films including 0–45° grain boundaries is a large residual surface resistance. The R s of almost perfectly in-plane aligned YBCO film scaled to 10 GHz were 0.12 mΩ at 20 K and 0.67 mΩ at 77 K on the assumption of tan δ =0, respectively.

Dielectric loss tangent of sapphire single crystal produced by edge-defined film-fed growth method

We investigated the dielectric loss tangent (tanδ) of sapphire single crystals produced by edge-defined film-fed growth (EFG) method using a dielectric resonator with YBa2Cu3Oy (YBCO) films. Surface resistance (Rs) of the YBCO film was low enough to obtain high resolution of tanδ measurement. For comparison, tanδ of the sapphire prepared by the Czochralsky (Cz) method was also evaluated. Measurements of 14 sapphire rods showed that EFG sapphire tends to have lower tanδ than Cz sapphire, while defects in Cz crystal were 1/14–1/2 less than that in EFG crystal. It means that the number of defects does not influence tanδ, if the density of defects is within the order of 104/cm2. In most EFG sapphire the value of tanδ at 30 K was estimated to be <1.0×10−7. It is usable for Rs measurement of high critical temperature superconducting materials.

Preparation of Tl-2212 and -1223 superconductor thin films and their microwave properties

Abstract Tl 2 Ba 2 CaCu 2 O y (Tl-2212) and Tl(Ba,Sr) 2 Ca 2 Cu 3 O y (Tl-1223) superconductor thin films have been prepared on CeO 2 buffered sapphire substrate by an ex situ process namely, amorphous phase epitaxy (APE) method. In the case of Tl-1223, an amorphous layer of TlSr 2 CaCu 2 O y (TlSr-1212) was deposited on top of CeO 2 layer to avoid chemical reaction between Tl-1223, containing Ba, and CeO 2 layers. All films are epitaxial with smooth surface and excellent crystallinity. Superconducting transition temperatures ( T c ) of Tl-2212 and 1223 are around 95 and 104 K, respectively. Critical current density ( J c ) at 77 K measured on 5×5 mm films by inductive technique is as high as 2 MA/cm 2 . Surface resistance R s of Tl-2212 films measured by a dielectric resonator technique at 38 GHz is comparable to the best YBCO films.

The effect of lattice matching between buffer layer and YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin film on in-plane alignment of c-axis oriented thin films

The effect of lattice matching between YBa/sub 2/Cu/sub 3/O/sub 7/, (YBCO) films and buffer layers as well as between buffer layers and MgO substrates have been discussed from viewpoints of crystalline, critical temperature and surface resistance of YBCO films. SrSnO/sub 3/(SSO) as well as BaSnO/sub 3/ (BSO) were used as buffer materials. SSO has closer lattice constant to YBCO than BSO. YBCO films were grown on these materials at the optimal growth temperature by pulse laser deposition. The FWHM of /spl phi/-scan (102) plane of YBCO films on SSO buffer layers was smaller than that of YBCO films on BSO buffer layers. However the values of FWHM of 005 rocking-curve of YBCO films on BSO buffer layer were smaller than that of YBCO films on SSO buffer layer. The difference of surface resistance between YBCO film on BSO buffer layer and YBCO film on SSO buffer layer was very small indicating superconducting properties are not mainly governed by lattice mismatch at this region. We obtained the same values for c-axis length and critical temperature in YBCO films on these materials.

In-Plane Orientation Control of C-Axis Oriented YBa 2Cu 3O 7-δ Films on MgO Substrates by BaSnO 3 Buffer Layers

A new BaSnO3 buffer layer is proposed for controlling the in-plane orientation of YBa2Cu3O7-δ films grown on MgO substrates. BaSnO3 buffer layers and YBa2Cu3O7-δ films are grown by pulsed laser deposition. 45° grain boundaries in YBa2Cu3O7-δ films grown on MgO (001) substrates, which are fatal defects for microwave device applications, are eliminated using the BaSnO3 buffer layer. YBa2Cu3O7-δ films grown at an optimum growth temperature of 710°C on BaSnO3 buffer layers on MgO (001) substrates show lower surface resistance (RS) than those on MgO (001) substrates without BaSnO3 buffer layers.

Closed-packed and well-aligned carbon nanotube films on SiC

Structures of (0?0?0? ) aligned carbon nanotubes (CNTs) formed by surface decomposition of the SiC(0?0?0? ) C-face in vacuum were investigated by cross-sectional, plan-view transmission electron microscopy and electron diffraction methods. Zigzag-type CNTs were confirmed to be selectively formed by this method and the formation mechanism was proposed by crystallographic analysis. The wall number of CNTs was found to be directly proportional to the diameter of CNTs. Compared with theoretical calculation, it was revealed that all carbon atoms remained on the surface after selective evaporation of Si atoms by the decomposition of each mono-layer of SiC(0?0?0? ) and then constructed the CNT walls with a minimum diffusion distance at the interface. For actual application of some nanotube devices, patterning of CNTs on the SiC substrate by the photoresist technique and fabrication of a large-area uniform CNT film on a 12?in. CVD-SiC substrate were demonstrated.Novel properties of energy absorption and anti-erosion wear affected by the flexibility of the CNT film were revealed by nano-indentation and erosion wear experiments.