9,994 research outputs found
Effect of Vinyl and Silicon Monomers on Mechanical and Degradation Properties of Bio-Degradable Jute-Biopol® Composite
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Composites of jute fabrics (Hessian cloth) and Biopol® were prepared by compression molding process. Three types of Biopol® (3-hydroxbutyrate-co-3-hydroxyvalarate) such as D300G, D400G and D600G, depending on the concentration of 3-hydroxyvalarate (3HV) in 3-hydroxbutyrate (3HB) were taken for this purpose. Mechanical properties such as tensile strength (TS), bending strength (BS), elongation at break (Eb) and impact strength (IS) of the jute-Biopol® composites were studied. It was found that the composite with D400G produced higher mechanical properties in comparison to the other two types of Biopol®. To increase mechanical properties as well as interfacial adhesion between fiber and matrix, 2-ethyl hydroxy acrylate (EHA), vinyl tri-methoxy silane (VMS) and 3-methacryloxypropyl tri-methoxy silane (MPS) were taken as coupling agents. Enhanced mechanical properties of the composites were obtained by using these coupling agents. Biopol® D400G composites showed the highest mechanical properties. Among the coupling agents EHA depicts the highest increase of mechanical properties such as tensile strength (80%), bending strength (81%), elongation at break (33%) and impact strength (130%) compared pure Biopol. SEM investigations demonstrate that the coupling agents improve the interfacial adhesion between fiber and matrix. The surface of the silanized jute was characterized by FTIR and found the deposition of silane on jute fiber was observed. Soil degradation test proved that the composite prepared with EHA treated jute exhibits better degradation properties in comparison to pure Biopol®
Ultra-low Q values for neutrino mass measurements
We investigate weak nuclear decays with extremely small kinetic energy
release (Q value) and thus extremely good sensitivity to the absolute neutrino
mass scale. In particular, we consider decays into excited daughter states, and
we show that partial ionization of the parent atom can help to tune Q values to
<< 1 keV. We discuss several candidate isotopes undergoing beta+, beta-, bound
state beta, or electron capture decay, and come to the conclusion that a
neutrino mass measurement using low-Q decays might only be feasible if no
ionization is required, and if future improvements in isotope production
technology, nuclear mass spectroscopy, and atomic structure calculations are
possible. Experiments using ions, however, are extremely challenging due to the
large number of ions that must be stored. New precision data on nuclear
excitation levels could help to identify further isotopes with low-Q decay
modes and possibly less challenging requirements.Comment: 7 pages, 2 figures; v2: Typos corrected, references adde
Metal-Insulator Transition of the LaAlO3-SrTiO3 Interface Electron System
We report on a metal-insulator transition in the LaAlO3-SrTiO3 interface
electron system, of which the carrier density is tuned by an electric gate
field. Below a critical carrier density n_c ranging from 0.5-1.5 * 10^13/cm^2,
LaAlO3-SrTiO3 interfaces, forming drain-source channels in field-effect devices
are non-ohmic. The differential resistance at zero channel bias diverges within
a 2% variation of the carrier density. Above n_c, the conductivity of the ohmic
channels has a metal-like temperature dependence, while below n_c conductivity
sets in only above a threshold electric field. For a given thickness of the
LaAlO3 layer, the conductivity follows a sigma_0 ~(n - n_c)/n_c characteristic.
The metal-insulator transition is found to be distinct from that of the
semiconductor 2D systems.Comment: 4 figure
Pitch-angle scattering in magnetostatic turbulence. I. Test-particle simulations and the validity of analytical results
Context. Spacecraft observations have motivated the need for a refined
description of the phase-space distribution function. Of particular importance
is the pitch-angle diffusion coefficient that occurs in the Fokker-Planck
transport equation. Aims. Simulations and analytical test-particle theories are
compared to verify the diffusion description of particle transport, which does
not allow for non-Markovian behavior. Methods. A Monte-Carlo simulation code
was used to trace the trajectories of test particles moving in turbulent
magnetic fields. From the ensemble average, the pitch-angle Fokker-Planck
coefficient is obtained via the mean square displacement. Results. It is shown
that, while excellent agreement with analytical theories can be obtained for
slab turbulence, considerable deviations are found for isotropic turbulence. In
addition, all Fokker-Planck coefficients tend to zero for high time values.Comment: 8 pages, 10 figures, accepted for publication in Astron. Astrophy
Two experiments for the price of one? -- The role of the second oscillation maximum in long baseline neutrino experiments
We investigate the quantitative impact that data from the second oscillation
maximum has on the performance of wide band beam neutrino oscillation
experiments. We present results for the physics sensitivities to standard three
flavor oscillation, as well as results for the sensitivity to non-standard
interactions. The quantitative study is performed using an experimental setup
similar to the Fermilab to DUSEL Long Baseline Neutrino Experiment (LBNE). We
find that, with the single exception of sensitivity to the mass hierarchy, the
second maximum plays only a marginal role due to the experimental difficulties
to obtain a statistically significant and sufficiently background-free event
sample at low energies. This conclusion is valid for both water Cherenkov and
liquid argon detectors. Moreover, we confirm that non-standard neutrino
interactions are very hard to distinguish experimentally from standard
three-flavor effects and can lead to a considerable loss of sensitivity to
\theta_{13}, the mass hierarchy and CP violation.Comment: RevTex 4.1, 23 pages, 10 figures; v2: Typos corrected, very minor
clarifications; matches published version; v3: Fixed a typo in the first
equation in sec. III
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