D6 Family Symmetry and Cold Dark Matter at LHC

We consider a non-supersymmetric extension of the standard model with a family symmetry based on D6 Z2 Z2, where one of Z2's is exactly conserved. This Z2 forbids the tree-level neutrino masses and simultaneously ensures the stability of cold dark matter candidates. From the assumption that cold dark matter is fermionic we can single out the D6 singlet right-handed neutrino as the best cold dark mater candidate. We find that an inert charged Higgs with a mass between 300 and 750 GeV decays mostly into an electron (or a positron) with a large missing energy, where the missing energy is carried away by the cold dark matter candidate. This will be a clean signal at LHC.Comment: 20 pages, 7 figure

Dissolution Behavior of SiO₂ and Electrochemical Reduction of Dissolved SiO₂ in Molten Chlorides

To develop a new production process for SOG-Si with high productivity and low energy consumption, the structure of silicate ions in molten eutectic NaCl–CaCl₂ containing dissolved SiO₂ was investigated by Raman spectroscopy. The existence of SiO₃²⁻ was indicated in melts containing 1.0 mol% of CaSiO₃ (O²⁻/SiO₂ = 1.0). When 1.0 mol% of CaO was further added to the melt (O²⁻/SiO₂ = 2.0), the existence of SiO₄⁴⁻ was indicated. Cyclic voltammetry and potentiostatic electrolysis were conducted in molten NaCl–CaCl₂ with different silicate ions. From cyclic voltammograms, XRD analysis, and SEM observation, silicate ions with different structure indicated different electrochemical reduction behavior; and the SiO₃²⁻ ion is likely to be more suitable than SiO₄⁴ ion for the electrodeposition of Si

Terahertz single pixel imaging based on a Nipkow disk

We describe a terahertz single pixel imaging system based on a Nipkow disk. Nipkow disks have been used for fast scanning imaging systems since the first experimental television was invented in 1926. In our work, a Nipkow disk with 24 scanning lines was used to provide an axial resolution of 2 mm/pixel. We also show that by implementing a microscanning technique the axial resolution can be further improved to 0.5 mm/pixel. Imaging of several objects was demonstrated to show that this simple scanning system is promising for fast and/or real time terahertz imaging applications

Electrodeposition of Si from Silicate Ions at Graphite and Liquid Zn Electrodes in Molten CaCl₂

To establish a next-generation production process for SOG-Si, we proposed the electrochemical reduction process of SiO₂ using a liquid Zn cathode in molten CaCl₂. In this study, we focused on the dissolved SiO₂ to improve the productivity of the process. The ionic species and electrochemical reduction of silicate ions at solid graphite and liquid Zn electrodes in molten CaCl₂ with various O²⁻/SiO₂ ratios (rO²⁻/SiO₂) at 1123 K were investigated. Ionic species of silicates in the melts were determined by Raman spectroscopy. The dominant species were SiO₃²⁻ (rO²⁻/SiO₂ = 1.0) and SiO₄⁴⁻ (rO²⁻/SiO₂ = 1.5 and 2.0). Cyclic voltammetry, XRD, and SEM revealed that the electrochemical reduction of SiO₃²⁻, Si₂O₇⁶⁻, and SiO₄⁴⁻ occurs at the graphite electrode from 1.35 V, 1.12 V, and 0.75 V vs Ca²⁺/Ca, respectively. The electrochemical reduction potentials of silicate ions at the liquid Zn electrode shifted to more negative values in the order SiO₃²⁻ > Si₂O₇⁶⁻ > SiO₄⁴⁻. The reaction observed at 0.60 V was attributed to the simultaneous electrochemical reduction of silicate ions and formation of Ca-Zn alloy. The indirect reduction of silicate ions by Ca-Zn alloy was also confirmed

Silicon Refining by Solidification from Liquid Si–Zn Alloy and Floating Zone Method

This study evaluated the refining ability of a proposed production process for solar-grade silicon utilizing the electrolytic reduction of SiO₂ on a liquid zinc electrode in molten salt. The distribution behaviors of impurity elements during the precipitation of solid silicon from a liquid Si–Zn alloy were studied by thermodynamic calculations at 923 K. In the precipitation experiment, silicon granules were recovered from a liquid Si–Zn alloy, which was prepared from metallurgical-grade silicon. The impurity removal ratios exceeded 99% for C, Al, and Ca, and 90% for Fe. High removal ratios were attained for B and O as well. As the post-processing, a silicon ingot was produced from the precipitated silicon granules by the floating zone method. The Zn residue in the precipitated silicon was completely evaporated during the floating zone refining. The total content of metallic elements (Al, Ca, Fe, Ti, and Zn) was lower than 0.2 ppmw, even though metallurgical-grade silicon was used as the starting material

Three-generation neutrino mixing and LSND dark matter neutrinos

The reported signal at the LSND experiment, when interpreted as neutrino mixing with $\delta m^2 = 6 \;\rm{eV}^2$, provides evidence for neutrinos with a cosmologically significant mass. However, attempts to reconcile this interpretation of the experiment with other hints about neutrino properties require a (sterile) fourth neutrino and/or an ``inverted'' neutrino mass hierarchy. An interpretation of the LSND experiment employing $\delta m^2 = 0.3\; \rm{eV}^2$, with three-generation mixing and a ``normal'' neutrino mass hierarchy, can just barely be reconciled with the negative results of other laboratory neutrino oscillation experiments and the positive hints of neutrino oscillation from the solar and atmospheric neutrino problems. Though subject to test by by future experiments, such a solution allows (but does not demand) neutrino masses relevant for dark matter.Comment: To be published in Nucl. Phys. B (Proc. Suppl.), in the proceedings of "Sources and Detection of Dark Matter in the Universe", held in Santa Monica, Feb. 14-16 1996. 5 page

Comparative study of the functional properties of lupin, green pea, fava bean, hemp, and buckwheat flours as affected by pH

Acknowledgments This work is part of the Strategic Research 2011–2016 and is funded by the Scottish Government’s Rural and Environment Science and Analytical Services Division (RESAS).Peer reviewedPublisher PD

Symmetry breaking and gap opening in two-dimensional hexagonal lattices

9 páginas, 3 figuras.-- et al.The inhibition in wave propagation at band gap energies plays a central role in many areas of technology such as electronics (electron gaps), nanophotonics (light gaps) and phononics (acoustic gaps), among others. Here we demonstrate that metal surfaces featuring free-electron-like bands may become semiconducting by periodic nanostructuration. We combine scanning tunneling spectroscopy and angle-resolved photoemisssion to accurately determine the energy-dependent local density of states and band structure of the Ag/Cu(111) noble metal interface patterned with an array of triangular dislocations, demonstrating the existence of a 25 meV band gap that extends over the entire surface Brillouin zone. We prove that this gap is a general consequence of symmetry reduction in close-packed metallic overlayers; in particular, we show that the gap opening is due to the symmetry lowering of the wave vector group at the K point from C3v to C3.This work was supported in part by the Spanish MICINN (MAT2007-66050, MAT2007-63083 and Consolider NanoLight.es), the EU (NMP4-SL-2008-213669-ENSEMBLE), the Basque Government (IT-257-07) and the Centre National de la Recherche Scientifique (CNRS).Peer reviewe

Investigation of the effect of double-walled carbon nanotubes on the curing reaction kinetics and shear flow of an epoxy resin

In this article, the effect of combined temperature-concentration and shear rate conditions on the rheology of double-walled carbon nanotubes (DWCNTs)/RTM6-Epoxy suspension was investigated to determine the optimum processing conditions. The rheological behavior and cure kinetics of this nanocomposite are presented. Cure kinetics analysis of the epoxy resin and the epoxy resin filled with DWCNTs was performed using Differential Scanning Calorimeter (DSC) and parameters of the kinetics model were compared. The DWCNTs have an acceleration effect on the reaction rate of the epoxy resin but no significant effect is noted on the glass transition temperature of the epoxy resin. This study reveals that the effect of shear-thinning is more pronounced at high temperatures when DWCNTs content is increased. In addition, the steady shear flow exhibits a thermally activated property above 60°C whereas the polymer fluid viscosity is influenced by the free volume and cooperative effects when the temperature is below 60°C