Study of Cuprate Superconductivity Using the Particle Number Conserving Bogoliubov-de Gennes Equations: ARPES and STS Images From Surface Plus Bulk Layers Model

Journal of Superconductivity and Novel Magnetism - We theoretically study the superconductivity in hole-doped cuprate superconductors by employing a model composed of surface and bulk CuO $$_2$$...     

A New Laser Induced Incandescence–Mass Spectrometric Analyzer (LII-MS) for Online Measurement of Aerosol Composition Classified by Black Carbon Mixing State

We developed a laser induced incandescence–mass spectrometric analyzer (LII-MS) for online measurements quantifying the aerosol chemical compositions with respect to the mixing state of black carbon (BC). The LII-MS is developed as a tandem series comprising an LII chamber to detect and vaporize BC-containing particles and a particle trap laser desorption mass spectrometer (PT-LDMS: Takegawa et al. 2012). The PT-LDMS collects aerosol particles transferred from the LII chamber and quantifies the chemical compositions. A newly designed collection probe, coupled with the sheath-air inlet nozzle of the LII chamber, enables a high throughput of aerosol particles without significant dilution. Total aerosol particles can be analyzed in the PT-LDMS by turning off the laser (MS mode), and the aerosol particles externally mixed with BC can be analyzed by turning on the laser (LII-MS mode). The difference in the PT-LDMS signals between the MS and LII-MS modes yields the chemical composition of materials internally mixed with BC. Performance of the developed instrument was evaluated in the laboratory by generating BC particles internally-mixed with oleic acid (OL) and BC particles externally mixed with ammonium sulfate particles. Preliminary results from ambient measurements are also presented and discussed.

Copyright 2014 American Association for Aerosol Research     

Numerical simulation of critical current performance in Nb3Sn strand subjected to periodic bending deformation

In the ITER Engineering Design Activity (EDA), four NB₃Sn model coils were developed and successfully tested. However, it was revealed that the critical current of the conductor degraded with the increase of electromagnetic force. One of the explanations of this phenomenon is a strand bending caused by enormous electromagnetic force. The authors therefore developed a simulation code using the distributed circuit model to investigate dependency of the critical current performance on the periodic bending deformation. The simulation results were in good agreement with the experiments. The dependence of the critical current on the periodic transverse load, temperature, periodic load pitch, thickness of Ta barrier which prevents Cu stabilizer from being contaminated by Sn, twist pitch of the strand, and RRR of the bronze matrix was investigated using the developed code. The results showed that the critical current degraded less with decreasing the pitch of the transverse load and increasing the Ta barrier thickness. It suggests that the shorter cabling pitch and the larger bending stiffness prevent the critical current degradation. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(3): 7–15, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20923     

Critical issues for the manufacture of the ITER TF coil winding pack

Research and trials by the Japan Atomic Energy Agency (JAEA) focus on the remaining technical issues in the ITER TF coil winding pack (WP) manufacturing process. Specific issues include the feasibility of automatically measuring conductor length during automatic winding with a high degree of accuracy (±0.02%) and a fabrication process to comply with the demanding tolerances (up to 1 mm distortion in flatness and 1.5 mm in-plane shrinkage) of the radial plate (RP) due to cover plate (CP) welding. The authors developed a new technique to measure conductor length very accurately by combining an ordinary encoder and a newly developed optical system. A simulation based on test results of CP welding using a RP mock-up indicates that a flatness of 1 mm is achievable, but the in-plane shrinkage of the RP is approximately 5 mm. One possible solution is to fabricate the RP larger than required to allow for in-plane shrinkage. Another solution is to reduce the thickness or length of the welding. The feasibility of these solutions to most of the major technical issues suggests that it is time for full qualification testing of the fabrication process in a dummy double-pancake trial.     

Behavior of composite segment for shield tunnel

Composite segment has been developed for obtaining high capacity in lining of shield tunnel subject to high hydraulic pressure and earth pressure in deep underground, which is made of steel plates connected to an infill of high fluidity concrete with shear connectors. However, a rational design method for composite segments can not be established, because the behavior of composite segments is not clarified. The purpose of this paper is to study the behavior of the most complicated composite segment with six steel plates using finite element method and the four-point bending tests. The effects of the shear studs and the thicknesses of steel plates were verified and estimated quantitatively. Meanwhile, the failure modes of composite segments were investigated. Comparisons show that the finite element model is suitable for composite segments and predicts the behavior of composite segments accurately.     

Spin-vortex Superconductivity

We present a theory of superconductivity based on the theoretical prediction that a macroscopic persistent current is generated by spin-vortices. It explains the origin of the phase variable θ that is canonical conjugate to the superfluid density as a Berry phase arising from the spin-vortex formation. This superconductivity does not require Cooper-pairs as charge carriers, thus, is not directly related to the standard theory based on the BCS one; however, it exhibits the flux quantization in the unit Φ ₀=hc/2|e|, where h is Planck’s constant, c the speed of light, and e the electron charge; and the AC Josephson frequency, f _J=2|e|V/h, where V is the voltage of the battery connected to the superconductor–insulator–superconductor junction. In due course, it is found that the standard derivation of the AC Josephson frequency misses a term arising from the flow of particles through the leads connected to the junction. If this contribution is included, the observed f _J indicates that the phase θ is a variable conjugate to the number density of charge e carriers instead of the currently accepted charge 2e carriers. We propose an experiment that discriminates whether it is e or 2e. If the above claim is verified, it means that the BCS theory cannot predict whether a particular compound is a superconductor or not since it does not explain the origin of θ. A connection between the present mechanism and the BCS mechanism is discussed; the fact that the BCS theory gives an excellent estimate of T _c is attributed to the fact that it predicts the temperature at which spin-vortices become long-lived due to the energy gap formation; since the stabilization by the electron-pair formation is compatible with the present mechanism, asymmetries observed in the even and odd number of electron systems are preserved. The most notable difference is that the persistent current generation is formulated in a strictly particle-number-conserving manner. Thus, it does not violate the superselection rule for the total charge.     

Production of ozone by surface and glow discharge at cryogenictemperatures

The generation of ozone at cryogenic temperatures is investigated with a special interest in increasing the yield of ozone by using low temperatures of liquid natural gas. Two modes of plasma chemical processes are studied, both based on electric discharges: one is the high-frequency surface discharge mode under ordinary gas pressure and at a temperature above the liquid temperature of ozone at this pressure (-111°C); the other is the glow discharge mode under a low gas pressure (0.5-2.0 torr) and low gas temperature (-190°C). The surface discharge mode uses a novel ozonizer developed by the authors made of 92% high-purity alumina and tungsten electrodes sintered together. This ozonizer has an extremely high resistance to large temperature gradients and thermal shock, which is a prerequisite for cryogenic operation. The glow discharge mode uses a Pyrex glow tube with a separate liquid-ozone collector. A dramatic improvement in the energy yield of ozone generation is achieved in both modes of cryogenic operation. The results of preliminary test for cryogenic ozone generation are very encouraging     

Localization of mRNA for inflammatory cytokines in radicular cyst tissue by in situ hybridization, and induction of inflammatory cytokines by human gingival fibroblasts in response to radicular cyst contents

The expression of mRNA encoding the inflammatory cytokines interleukin-1alpha (IL-1alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor alpha(TNF-alpha) have been examined in radicular cysts by in situ hybridization. Furthermore, the biological activity of the contents of radicular cysts (RCC) has been assayed by adding extracts of RCC to cultured human gingival fibroblasts (HGFs) and analyzing the culture medium for the release of inflammatory cytokines. In the epithelial layer, keratinocytes expressed all cytokine mRNAs examined at various levels. Basal layer cells expressed mRNA for each cytokine. In the subepithelial granulation tissue of the cysts, fibroblasts and macrophages expressed mRNA for IL-6, IL-8, IL-1beta and TNF-alpha mRNA at varying levels; especially clear expression of TNF-alpha and IL-1beta mRNA was detected on macrophages. The infiltrating lymphoid cells, largely composed of T cells and plasma cells, expressed these cytokine mRNAs, especially those encoding IL-6 and IL-8, at various levels. In vitro analysis indicated dose-dependent release of both IL-6 and IL-8 by HGFs in response to RCC. After heating to 100 degrees C for 10 min, RCC almost completely failed to stimulate IL-6 release from HGFs. Furthermore, anti-IL-1beta antibody (neutralization test) did not prevent the stimulation of IL-6 release by RCC. Significant amounts of IL-6 and IL-8 were detected in RCC in two cases, and a trace amount of IL-1beta was detected in one case. This study demonstrated the wide expression of mRNA encoding inflammatory cytokines in radicular cyst tissues, and RCC itself was capable of stimulating IL-6 and IL-8 production from HGFs.     

Phase study on solid fission products,Ba, Sr and Zr in oxide fuel

Behavior of pseudo-fission products (Ba, Sr, and Zr) as oxides in UO₂ has been investigated by means of high-temperature X-ray diffraction and microprobe analysis. Two identifiable compounds were formed as reaction products in the mixed oxides which initially consisted of UO₂, BaO, SrO, and ZrO₂ powder. These compounds were present and were identified crystallographically as (Ba, Sr) ZrO₃ and (Ba, Sr)UO₃ after heat treatment of the powders at 1500°C for 30 min. Both compounds are isostructural with perovskite, CaTiO₃, and the lattice parameters of both (Ba, Sr)ZrO₃ and (Ba, Sr)UO₃ decrease with increasing content of Sr. (Ba, Sr)UO₃ is decomposed almost completely at 1800°C while (Ba, Sr) ZrO₃ is stable up to 2000°C. The behavior of Ba, Sr, and Zr in fuel under irradiation is discussed.     

Transition of sulfospinel to Th3P4 type phase under pressure

Sulfospinels AB₂S₄ (A=Mg, Mn, B=Tm, Yb) were treated at 1000°C and 55 kbar for 1h. The X-ray powder diffractions were completely indexed by assuming that the products were isostructural with Th₃P₄. The results of density measurements showed a good agreement with those calculated from the X-ray data. No magnetic ordering was observed in temperatures down to 77K.