40,784 research outputs found
An improved method for analysis of hydroxide and carbonate in alkaline electrolytes containing zinc
A simplified method for titration of carbonate and hydroxide in alkaline battery electrolyte is presented involving a saturated KSCN solution as a complexing agent for zinc. Both hydroxide and carbonate can be determined in one titration, and the complexing reagent is readily prepared. Since the pH at the end point is shifted from 8.3 to 7.9 - 8.0, m-cresol purple or phenol red are used as indicators rather than phenolphthalein. Bromcresol green is recommended for determination of the second end point of a pH of 4.3 to 4.4
Chromium electrodes for REDOX cells
An improved electrode having a gold coating for use in the anode compartment of a REDOX cell is described. The anode fluid utilizes a chromic/chromous couple. A carbon felt is soaked in methanol, rinsed in water, dried and then heated in KOH after which it is again washed in deionized water and dried. The felt is then moistened with a methanol water solution containing chloroauric acid and is stored in a dark place while still in contact with the gold-containing solution. After all the gold-containing solution is absorbed in the felt, the latter is dried by heat and then heat treated at a substantially greater temperature. The felt is then suitable for use as an electrode and is wetted with water or up to two molar HCl prior to installation in a REDOX cell. The novelty of the invention lies in the use of KOH for cleaning the felt and the use of alcohol as a carrier for the gold together with the heat treating procedure
Vehicle Steering control: A model of learning
A hierarchy of strategies were postulated to describe the process of learning steering control. Vehicle motion and steering control data were recorded for twelve novices who drove an instrumented car twice a week during and after a driver training course. Car-driver describing functions were calculated, the probable control structure determined, and the driver-alone transfer function modelled. The data suggested that the largest changes in steering control with learning were in the way the driver used the lateral position cue
Chemical and electrochemical behavior of the Cr(3)/Cr(2) half cell in the NASA Redox Energy Storage System
The Cr(III) complexes in the NASA Redox Energy Storage System were isolated and identified as Cr(H2O)6(+3) and Cr(H2O)5Cl(+2) by ion exchange chromatography and visible spectrophotometry. The cell reactions during charge-discharge cycles were followed by means of visible spectrophotometry. The spectral bands were resolved into component peaks and concentrations calculated using Beer's Law. During the charge mode Cr(H2O)5Cl(+2) is reduced to Cr(H2O)5Cl(+) and during the discharge mode Cr(H2O)5Cl(+) is oxidized back to Cr(H2O)5Cl(+2). Both electrode reactions occur via a chloride-bridge inner-sphere reaction pathway. Hysteresis effects can be explained by the slow attainment of equilibrium between Cr(H2O)6(+3) and Cr(H2O)5Cl(+2)
A chondrule in the Chainpur meteorite
Glass occurrence in chondrules as evidence for formation by rapid cooling of liquid droplets - chondritic meteorite
Gauge Symmetry, T-Duality and Doubled Geometry
String compactifications with T-duality twists are revisited and the gauge
algebra of the dimensionally reduced theories calculated. These reductions can
be viewed as string theory on T-fold backgrounds, and can be formulated in a
`doubled space' in which each circle is supplemented by a T-dual circle to
construct a geometry which is a doubled torus bundle over a circle. We discuss
a conjectured extension to include T-duality on the base circle, and propose
the introduction of a dual base coordinate, to give a doubled space which is
locally the group manifold of the gauge group. Special cases include those in
which the doubled group is a Drinfel'd double. This gives a framework to
discuss backgrounds that are not even locally geometric.Comment: 16 page
A Trigonometric Parallax of Sgr B2
We have measured the positions of water masers in Sgr B2, a massive star
forming region in the Galactic center, relative to an extragalactic radio
source with the Very Long Baseline Array. The positions measured at 12 epochs
over a time span of one year yield the trigonometric parallax of Sgr B2 and
hence a distance to the Galactic center of Ro=7.9 (+0.8/-0.7) kpc. The proper
motion of Sgr B2 relative to Sgr A* suggests that Sgr B2 is about 0.13 kpc
nearer than the Galactic center, assuming a low-eccentricity Galactic orbit.Comment: Submitted to ApJ; 4 tables; 3 figures. Version 2 corrects Fig. 2
which was missing some dat
Tripartite entanglement from interlinked parametric interactions
We examine the tripartite entanglement properties of an optical system using
interlinked interactions, recently studied experimentally in terms
of its phase-matching properties by Bondani et al [M. Bondani, A. Allevi, E.
Gevinti, A. Agliati, and A. Andreoni, arXiv:quant-ph/0604002.]. We show that
the system does produce output modes which are genuinely tripartite entangled
and that detection of this entanglement depends crucially on the correlation
functions which are measured, with a three-mode Einstein-Podolsky-Rosen
inequality being the most sensitive.Comment: 15 pages, 5 figure
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