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We report the epitaxial growth of CuO thin films prepared by lowenergy and high-density O+ ion beams mass-separated from an oxygen plasma. We have successfully produced O+ beams of 50 μA/cm2 while maintaining an ambient pressure of 3×10−9 Torr during the growth. CuO grows on MgO(100) with epitaxial relationship of (111)CuO // (100)MgO and CuO // MgO at room temperature and even under conditions where the flux density of O+ beams is at least one order of magnitude lower than the minimum flux density of O2 required to form CuO.
We performed molecular dynamics simulations to investigate the process of defect production in pure vanadium. The interaction of atoms was described by the EAM interatomic potential modified at short range to merge smoothly with the universal potential for description of the high energy recoils in cascades. The melting point of this EAM model of vanadium was found to be consistent with the experimental melting temperature. The threshold energies of displacement events in the model system are also consistent with experimental minimum threshold in vanadium, and its average was found to be 44 eV. We evaluated the efficiencies of defect production in the displacement events initiated by recoils with kinetic energy up to 5 keV, and found that the probability of cluster formation is smaller than that of simulated events in fee metals reported in the literature.
Superconducting films of YBa2Cu3O7-δ have been fabricated by pulsed laser deposition technique applying bias voltage to a substrate up to +/-500 V. It has been found that substrate bias voltages are effective for preparing the fidms with high Tc and high crystalline quality at lower substrate temperatures. Positive bias is more effective than negative one. Time resolved observation has been carried out in order to investigate the influence of biasing on the plume and revealed three kinds of light emission. The first is an ordinary plume with a velocity of 6×105 cm/s, which is independent of biasing. It suggests that most of the luminous particles in the plume are electrically neutral. The second is oxygen plasma with a short life time, which is triggered by laser pulse under the positive bias and triggered by arrival of the plume in 8 ps after the laser pulse under the negative bias. The third is an additional plume with a velocity of 3×105 cm/s. The oxygen plasma and additional plume have improved superconducting properties of films deposited with biasing to the substrate.
Total Reflection Angle X-Ray Spectroscopy with Reflection High Energy Electron Diffraction (RHEED-TRAXS) is a highly sensitive method for surface analysis. Yba2Cu3O7-x films of less than 1 unit cell average coverage can be detected by its characteristic x-rays. We grew YBCO films on MgO substrates by laser-ablation with two different kinds of surface morphology; one had few particles on a flat surface and the other had many long and narrow islands on the surface which we call linear islands. We measured the take-off angle dependence of TRAXS on these films. For the YBCO films with linear islands the intensities of YLα, BaLα and CuKα x-ray lines have shoulders at the critical angles given by a theoretical formula. For the YBCO films with smooth surfaces, only the BαLa intensity had a sharp peak at the critical angle. The result suggests that a BaO layer terminates YBCO films, or that a chemical reaction occurs at the surface and Ba compounds is produced.
Si KB X-ray emission spectra of SiO2—CaO binary glasses simulated with the DV-X α molecular orbital calculation were compared with ones measured by EPMA. The composition of the glass has been incorporated in the calculation of the Si 3p partial density of states (PDOS). The Si 3p PDOS, as a function of the CaO content, agreed well with the measured Si Kβ X-ray emission spectra of the 62.4mol%SiO2 – 37.6mol%CaO and 43.3mol%SiO2 – 56.7mol%CaO binary glasses. The present method was found to provide a very useful means of clarifying the change in the ionic configuration of the glass with the metal oxide content.
Method of electromagnetic acoustic resonance (EMAR) was applied to the noncontact measurement of the shear wave attenuation during the creep test of 2.25Cr-1Mo steels. Two electromagnetic acoustic transducers were manufactured for this purpose, which generate the polarized shear waves through the magnetostriction effect. The attenuation coefficient increased with the creep deformation. The evolution range of the attenuation was beyond 0.1 μs−1 before the failure, which was much larger than the attenuation variation among the samples.
In March 1989 a large outbreak of acute gastroenteritis occurred simultaneously among schoolchildren and teachers at nine elementary schools in Toyota City, Japan. Illness was observed in 3236 (41·5%) of 7801 schoolchildren and 117 (39·4%) of 297 teachers. The main clinical symptoms were diarrhoea, vomiting, nausea and abdominal pain. Gastroenteritis was significantly associated with the consumption of school lunch served by one particular lunch preparation centre. One food handler at the centre suffered from gastroenteritis during the outbreak.Small round structured virus (SRSV) was detected in 4 of 8 stool specimens from sick persons. The school lunch contaminated by the infected food handler is the most probable source of this outbreak due to SRSV.
Coexisting Ba-rich (Cn56–59Or40–42Ab2An0–1) and Ba-poor (Cn7–15Or83–92Ab1–3An0–1) feldspars were found in a jadeitite collected from the Itoigawa-Ohmi district in the Renge high-P/T-type metamorphic belt, Japan. There is an apparent compositional gap in these barian feldspars at Cn15–56 in the ternary system BaAl2Si2O8–KAlSi3O8–NaAlSi3O8. Barian feldspars occur as interstitial phases between subhedral to euhedral jadeite and prehnite, and sometimes cut a jadeite crystal. The occurrence of barian feldspars combined with the texture and mineral assemblages of the host jadeitite suggest that barian feldspars were formed from residual fluids after the formation of jadeite and prehnite from primary aqueous fluids at low-T conditions (<350°C) and pressure of ~0.6 GPa. The Ba content in the residual fluids would increase locally during the formation of jadeite because Ba is incompatible with clinopyroxene. This study supports the suggestion that Ba-rich minerals are not uncommon in jadeitites and albitites/metasomatized rocks that occur as tectonic blocks in serpentinite-matrix mélanges. Barium is an important minor element in metasomatizing fluids related to the formation of jadeitites and might have been derived from subducted oceanic crust at the beginning of the subduction.
Sera from 27 children and eight older persons, which had been collected in 1998 and 1999 and showed haemagglutination–inhibition (HI) activity against influenza A/Sydney/5/97 (H3N2) strain, were characterized with a binding assay using chimeric haemagglutinin (HA) proteins between A/Aichi/2/68 (A/AI/68) and A/Sydney/5/97 (A/SD/97) strains. Sera from the young children had a tendency to recognize only the antigenic site B1 of the HA1 region. On the other hand, sera of the older individuals were fully reactive to all antigenic sites of HA1 except antigenic site D. Recent epidemic strains, A/Panama/2007/99 (A/PM/99)-like viruses have differences in amino acids in antigenic sites A, C, and B2 but not B1. However, human antisera obtained even from young children had HI activity to Panama-like viruses. The limited epidemic of A/PM/99-like viruses may have been due to the existence of antibody against B1, which had been produced in response to infection by the A/SD/97-like viruses.
c-Axis-oriented (Hg0.9Re0.1)Ba2CaCu2Oy thin films were grown on the (100) plane of SrTiO3 substrates by a so-called two-step process. Transmission electron microscopic observation revealed that, in the film annealed under a higher temperature, some steplike regions appeared at the top layer of SrTiO3 substrate. High-resolution transmission electron microscopic images showed that the lattice parameters in these regions are about 4.05–4.15 Å, being longer than the lattice parameter of SrTiO3. It is supposed that a chemical reaction occurred in these regions, and a phase of (Bax,Sr1−x)(Cuy,Ti1−y)O3δs was formed by partially substituted Ba for Sr and Cu for Ti.
In order to conduct a survey of influenza viruses entering Japan via travellers arriving by
airplanes, gargle solutions were collected from passengers who reported to the quarantine
station of Nagoya International Airport complaining of respiratory symptoms. From 504
samples collected between August 1996 and March 1999, 30 influenza virus strains were
isolated. Twenty-eight of the isolates were influenza A (H3N2) viruses and two were influenza
B viruses. No H1N1 virus was isolated. Among 28 isolates of H3N2 virus, 3 strains were
obtained outside the influenza season. Nucleotide sequences of the haemagglutinin (HA) genes
of these isolates along with those from domestic patients were analysed in order to determine
the influence of imported influenza viruses by travellers on epidemics in Japan. From the
phylogenetic and chronological aspects, the possibility was suggested in one case in 1997/8 and
two in the 1998/9 season that imported virus by travellers may have influenced the domestic
Two phenotypes of human influenza A(H1N1) virus are currently
circulating in Japan. One
(group 1) agglutinates both chicken and goose red blood cells (CRBC and
the other (group 2) agglutinates GRBC but not CRBC. In the 1995/6 season,
2 viruses accounted
for 70% of the H1N1 viruses isolated in MDCK cells. The 1995/6 viruses
were located on two
branches of the genetic tree. One branch contained both group 1 and group
2 viruses and the
other branch contained only group 2 viruses. Group 2 viruses had aspartic
acid at residue 225
in the haemagglutinin (HA) protein, the key amino acid residue for group
2 phenotype. The
HA protein of group 1 viruses had a change from aspartic acid to asparagine
at residue 225
and the expressed HA protein of these viruses adsorbed CRBC. Serial
passage of group 2
viruses in MDCK cells or embryonated chicken eggs caused these viruses
gain the ability to
agglutinate CRBC. MDCK-adapted viruses had the same amino acid sequences
polypeptide as the original ones, but egg-adapted viruses had changed
amino acid sequences.
The expressed HA protein from one egg-adapted virus that originally
belonged to group 2 adsorbed CRBC.
Highly in-plane aligned α-axis YBa2Cu3O7−x thin films deposited on (100) LaSrGaO4 substrates by a self-template method were studied by high-resolution electron microscopy along three orthogonal 〈100〉 axes of the substrate. Plan-view images confirm that the majority of the film preferentially aligns across the entire substrate except for very few misaligned domains with average size 10 nm2. Cross-sectional images along the  orientation of YBa2Cu3O7−x reveal that in-plane aligned α-axis YBa2Cu3O7−x is grown on a template layer dominated by c-axis oriented film. This strongly suggests that the in-plane alignment of α-axis YBa2Cu3O7−x thin films on (100) LaSrGaO4 substrates is governed by the different stresses along the b and c axes of the substrate. Cross-sectional images along  of the YBa2Cu3O7—x thin film reveal that the 90° domains easily nucleate in the region between α-axis YBa2Cu3O7—x and the YBa4Cu3Ox phase. Cracks along the (001) plane of YBa2Cu3O7−x are found to be due to the large mismatch between the c parameters of the thin film and substrate.
Time of flight (TOF) spectroscopic measurements are used to diagnose the laser-generated plume of ceramic NdBa2Cu3Ox targets. We have been able to directly correlate the laser-deposited films' properties such as superconductivity, crystallinity, and orientation with plasma properties. Study of the TOF spectra shows that at laser fluences greater than 3 J/cm2 the plume become Nd-rich, and this leads to a low Tc in the deposited film. We have also shown the effect of target density on the energy of the plume species, and through energy considerations we have explained the observed change in the crystalline orientation of films from c- to a-orientation with increasing the target density. Finally, we have examined the oxidation mechanism of NdBa2Cu3Ox thin films, and have shown that highly energetic atomic oxygens have a prevailing role in oxidizing our laser-deposited thin films.
Microstructures of a-axis oriented YBa2Cu3O7−x films made by newly developed de 100 MHz hybrid plasma sputtering were investigated using transmission electron microscopy (TEM). The films deposited on (110) NdGaO3 and (100) SrTiO3 substrates were found to grow in a perfect epitaxial fashion and with clear interface. The plan view of the TEM image showed that both films were comprised of two kinds of grains having the c axis aligning along two perpendicular directions in the plane with equal probability. The structures of the grain boundary, however, were found to be very different for the two films from the plan views. The film on NdGaO3 showed a lot of twist boundaries, while the film on SrTiO3 consisted of many symmetrical tilt boundaries and basal-plane-faced tilt boundaries. The type of grain boundary is determined by the anisotropic growth rates of the film between c direction and a-b direction.
The a-axis oriented YBa2Cu3Ox (YBCO) films were epitaxially grown on (100) SrTiO3 substrate by dc-100 MHz hybrid plasma sputtering. The films prepared at different temperatures with and without in situ annealing had different superconductivity, which was improved with the degradation of the crystallinity of the films. The Raman spectra for the films were very similar to each other and to that expected for YBa2Cu3O7, in spite of the different superconductivity. This indicates the importance of the symmetry of the Cu–O chains rather than the oxygen content for the superconductivity. In Rutherford backscattering measurements using a 3.05 MeV He2+ ion beam, an increase of dechanneling due to the barium atoms along the film depth was clearly observed only for the most improved superconducting film. This result suggests that the relief of the strain contained in the film is also important for improving the superconductivity in the case of a-axis oriented YBCO films.
Optical emission spectroscopic studies of dc-94.92 MHz hybrid plasma generated in the newly developed magnetron sputtering system were performed during the growth of YBa2Cu3O7−δ (YBCO) thin films. All the detectable species showed uniform spatial distribution along the radial direction of the target more than 8 mm above the target surface. High cathode current conditions in the hybrid plasma were found to make the plasma with high ion density. The high ionizing efficiency was concluded to be essential in obtaining an excellent crystalline film. This result is explained by the ion acceleration mechanism through the ion sheath formed near the substrate surface. Oxygen gas introduced into the growing chamber during deposition was found to be responsible for the oxidation of the target surface.
C-axis oriented ultrathin films with good crystallinity were deposited by laser ablation on both SrTiO3 and NdGaO3 substrates. The full width at the half maximum of the rocking curves of the (005) peak δω of our ultrathin films with thickness d ≤ 150 Å is less than 0.11°, and the χmin of the 150 Å films on SrTiO3 determined by RBS is equal to 8.5%. SrTiO3 and NdGaO3 have different degrees of lattice mismatches of 2% and 0.2%, respectively, with YBa2Cu3O7−δ at the deposition temperature of 700 °C. To study the impact on the growth of YBa2Cu3O7−δ thin films by the lattice mismatch, the thickness dependence of the crystallinity of the films on SrTiO3 and NdGaO3 substrates was compared. δω of the films deposited on SrTiO3 increases slightly from 0.085° to 0.11° as d increases from 50 Å to 150 Å, but δω increases rapidly from d ≍ 150 Å and saturates at 0.35°. In contrast, films on NdGaO3 showed a rather flat thickness dependence of δω which is below 0.1°. We interpreted the rapid increase in δω of the films on SrTiO3 in terms of strain relaxation. Lattice matching is one of the key factors to obtain good crystallinity. The grains of the films on SrTiO3 and MgO are not flat and smooth but have “mosaic texture.” In contrast, the films on NdGaO3 have no mosaic texture. The possible origins of the mosaic texture are also discussed.