A spectroscopic study of radiation produced in a theta-pinch

Preliminary results of the analysis of the spectra of four times ionized krypton, Kr-V, are presented. 28 transitions were classified and for five of them the classification is new. We also present the UNICAMP theta-pinch for the study of highly ionized atoms. This device is now in testing.     

Genomics of industrial Aspergilli and comparison with toxigenic relatives

Aspergillus oryzae has been used in Japanese fermentation industries for more than a thousand years. The species produces large amounts of various hydrolytic enzymes and has been successfully applied to modern biotechnology. The size of the A. oryzae genome (37.5 Mb) is very close to that of A. flavus and A. niger, and 20-30% larger than that of either A. nidulans or A. fumigatus. A. oryzae and A. flavus have exactly the same number of aspartic proteinase genes, of which each orthologous pair shares highly conserved amino acid sequences. Synteny analysis with A. fumigatus and A. nidulans showed that the A. oryzae genome has a mosaic structure consisting of syntenic and non-syntenic blocks. In the microorganisms to be compared, the density of the genes having homologs was obviously higher on the syntenic than on the non-syntenic blocks. Expression analysis by the DNA microarray supported the significantly lower expression of genes on the non-syntenic than on the syntenic blocks.     

Indentation-induced ductile behavior of glass–ceramics involving layered aluminosilicates

Contact damage in materials is critical in engineering applications because it influences mechanical resistance, such as wear, erosion, and impact failure. Indentation tests were performed using a tungsten carbide ball indenter (Hertzian contact) on the surfaces of glass–ceramics containing hexagonal CaAl₂Si₂O₈ or mica crystals (fluorophlogopite), both of which have a layered structure. The stress–strain relation and the permanent deformation on the surface, as well as the observation of the microcrack zone by X-ray computed tomography using synchrotron radiation, revealed that the glass–ceramic with hexagonal CaAl₂Si₂O₈ showed ductility similar to the quasi-plastic behavior previously observed in the mica glass–ceramic. The yield stresses of the glass–ceramics were estimated from the stress deviating from the stress–strain relation assuming complete elastic response between the ball and the sample. The ratio of the yield stress to Young modulus (Y/E) of the glass–ceramic with hexagonal CaAl₂Si₂O₈ was determined to be higher than that of the mica glass–ceramic.     

Dynamical Instability of Coreless Vortices in F=2 Spinor Bose-Einstein Condensates

We theoretically investigate the low-lying excitation spectra of coreless vortex states in Bose-Einstein condensates (BECs) with F=2 hyperfine spin degrees of freedom. Here, we extend the previous work in F=1 spinor BEC. In addition to the dynamical instabilities in F=1 coreless vortex states, we find an another set of dynamical instabilities due to different hyperfine spin interaction. The calculation is carried out in the possible parameter space of the F=2 ⁸⁷Rb atom. This study assists interpretation of experimental data and presents a general characteristics of the dynamical instability of F=2 hyperfine spin system. whether the ground state of the spin interaction is in the cyclic or polar phase. Our study can encourages the experiments to examine our results.     

Determination of atomistic deformation of tricalcium silicate paste with high-volume fly ash

We examined the effect of incorporating high-volume fly ash on the atomic arrangement and interatomic deformation behavior of calcium silicate hydrates in tricalcium silicate paste upon exposure to external forces. The interatomic structural changes and strains under compressive load were assessed using synchrotron in situ high-energy X-ray scattering-based atomic pair distribution function analysis. Three different types of strains, which were (a) macroscopic strains from gauges on the surfaces of specimen, (b) strains in a reciprocal space (Bragg peak shift), and (c) strains in real space (PDF peak shift), were compared to each other. All monitored and calculated strains for tricalcium silicate-fly ash (50 wt% fly ash) paste were compared with the counterparts of the pure tricalcium silicate paste. Pair distribution function analysis in the range of r < 10 Å indicated that the atomic arrangement of tricalcium silicate-fly ash was similar to that of synthetic calcium silicate hydrates followed by that of pure tricalcium silicate paste. Moreover, the pair distribution function refinement results revealed that the calcium silicate hydrate structure in tricalcium silicate-fly ash paste was similar to tobermorite 11 Å, unlike that in pure tricalcium silicate paste. The interatomic strain of tricalcium silicate-fly ash in the real space (r < 20 Å) was smaller than that of tricalcium silicate under compression, which suggested that the incompressibility of calcium silicate hydrates at atomistic scale was enhanced by the incorporation of fly ash into it. This was likely to be caused by the increased silicate polymerization of calcium silicate hydrates, which was attributed to the increase in the amount of silicate in their structure via the addition of fly ash.     

Dispersion-free single-mode fibre transmission experiments up to 1.6 Gbit/s

Long-span single-mode fibre transmission experiments at 1.3 ?m have been refined toward higher digit rate and longer fibre span. Error-rate against receiving optical level characteristics showed that optical power penalties at 100 Mbit/s, 1.2 Gbit/s and 1.6 Gbit/s are negligible, even after 30 km, 23 km and 13 km fibre transmission, respectively.     

Optical-transmission experiment at 400 mb/s using a graded-index fibre

An optical-transmission error-rate experiment is described in which a graded-index fibre up to 5 km long is used as a transmission medium. It is shown that impairments in the transmission are mainly determined by the total frequency response of the transmission medium, including the fibre and its connection.     

Effect of Zn, Ni and Fe Impurities on Bi2Sr1.6La0.4CuO6+��

We measured the change of T _c with the doping of the magnetic and nonmagnetic impurity in Bi₂Sr_1.6La_0.4CuO_6+?? (Bi2201). The reduction of T _c is about 20% in samples with Zn (1.1%), Ni (1.0%), and Fe (1.2%), and a slight difference was observed among these samples. We also observed the resonance peak at the Zn-impurity site by scanning tunneling spectroscopy at 4.2 K. The observed resonance peak showed the four-fold symmetry, and appeared at approximately ?1.5 meV.     

Vesicles from sucrose fatty acid esters

It has been confirmed, from observations with an electron microscope after staining negatively with aqueous uranyl acetate solutions and using a flourescent microscope, that sucrose fatty acid esters form closed vesicles. The range of particle size of the vesicle, consisting of chromatographically fractionated sucrose dilaurate, was apparently 70–700 nm in the longer diameter of individual vesicles based on the transmission electron microscopic (TEM) observation. The weight-average particle size was 424 nm as shown by means of the photon-correlation method. The amounts of 6-carboxyfluorescein trapped in the vesicles of sucrose fatty acid esters were determined, and it was ascertained that the volumes of the central water phase depended upon the acyl chain lengths of fatty acid residues. Further, the effect of the additives [cholesterol and dicetyl phosphate (DCP) was examined. As an example, the vesicle of sucrose stearate had a central water phase of 1.7 one water/mol ester, and showed a slow release of 6-carboxyfluorescein from the central water phase after preparation of the vesicle.