Equivalent circuit parameters of the film-covered magnesium/electrolyte interface in Mg/MnO2 dry cells from transient and ac impedance measurements

The electrochemical properties of the film-covered anode/solution interface in the magnesium/ manganese dioxide dry cell have been evaluated. The most plausible electrical equivalent circuit description of the Mg/solution interface with the passive film intact, has been identified. These results are based on the analysis of ac impedance and voltage transient measurements made on the dry cell under conditions which cause no damage to the protective passive film on the anode. The study demonstrates the complementary character of impedance and transient measurements when widely different frequency ranges are sampled in each type of investigation. The values and temperature dependence of the anode-film resistance, film capacitance, double-layer capacitance and charge-transfer resistance of the film-covered magnesium/solution interface have been determined. The magnitude of these values and its implications in understanding the important performance aspects of the magnesium/manganese dioxide dry cell are discussed. The study may be extended, in principle, to Li, Al and Ca batteries.

Ionic conductivity and dielectric measurements in single crystal β---AgI

Ionic conductivity measurements have been made on pure, copper-doped and cadmium-doped single crystals. Dielectric measurements in the frequency range 30Hz–100Hz showed that there was no anomalously to be (0.64 ± 0.02) eV and migration energies for silver ion intersitials and vacancies in the c direction to be (0.41 ± 0.02) eV and (0.50 ± 0.02) eV respectively. ESR measurements have shown that copper exists as Cu+ in these crystals. Dielectric measurements in the frequency range (OHz–100KHz showed that there was no anomalously high value for ε as reported earlier.

Accelerometer-Based Force Balance for High Enthalpy Facilities

A single component accelerometer-based force balance is developed, calibrated, and used for high enthalpy applications. Functionality of this force balance, for such applications, is demonstrated for the first time during high enthalpy tests in a newly established free piston-driven shock tunnel, HST3, using a 60 degrees apex angle blunt cone model at 0 degrees angle of incidence. Usefulness of this force balance is also confirmed, for much complicated high enthalpy flow situations, during the drag reduction studies with counterflow supersonic jet from the stagnation point.

Supramolecular Chirality in Organogels: A Detailed Spectroscopic, Morphological, and Rheological Investigation of Gels (and Xerogels) Derived from Alkyl Pyrenyl Urethanes

This Article addresses the formation of chiral supramolecular structures in the organogels derived from chiral organogelator 1R (or 2R), and its mixtures with its enantiomer (1S) and achiral analogue 3 by extensive circular dichroism (CD) spectroscopic measurements. Morphological analysis by atomic force microscopy (AFM) and scanning electron microscopy (SEM) were complemented by the measurements of their bulk properties by thermal stability and rheological studies. Specific molecular recognition events (1/3 vs 2/3) and solvent effects (isooctane vs dodecane) were found to be critical in the formation of chiral aggregates. Theoretical studies were also carried out to understand the interactions responsible for the formation of the superstructures.

Miniature Compliant Grippers With Vision-Based Force Sensing

This paper is concerned with grasping biological cells in aqueous medium with miniature grippers that can also help estimate forces using vision-based displacement measurement and computation. We present the design, fabrication, and testing of three single-piece, compliant miniature grippers with parallel and angular jaw motions. Two grippers were designed using experience and intuition, while the third one was designed using topology optimization with implicit manufacturing constraints. These grippers were fabricated using different manufacturing techniques using spring steel and polydimethylsiloxane ( PDMS). The grippers also serve the purpose of a force sensor. Toward this, we present a vision-based force-sensing technique by solving Cauchy's problem in elasticity using an improved algorithm. We validated this technique at the macroscale, where there was an independent method to estimate the force. In this study, the gripper was used to hold a yeast ball and a zebrafish egg cell of less than 1 mm in diameter. The forces involved were estimated to be about 30 and 10 mN for the yeast ball and the zebrafish egg cell, respectively.

Inorganic Analogues of Graphene

The discovery of graphene has aroused great interest in the properties and phenomena exhibited by two-dimensional inorganic materials, especially when they comprise only a single, two or a few layers. Graphene-like MoS2 and WS2 have been prepared by chemical methods, and the materials have been characterized by electron microscopy, atomic force microscopy (AFM) and other methods. Boron nitride analogues of graphene have been obtained by a simple chemical procedure starting with boric acid and urea and have been characterized by various techniques that include surface area measurements. A new layered material with the composition BCN possessing a few layers and a large surface area discovered recently exhibits a large uptake of CO2.

Comparative measurements of HV impulses to evaluate different sets of response parameters

Results are reported of comparative measurements made in 14 HV (high-voltage) laboratories in ten different countries. The theory of the proposed methods of characterizing the dynamic behavior is given, and the parameters to be used are discussed. Comparative measurements made using 95 systems based on 53 dividers are analyzed. This analysis shows that many of the system now in use, even though they fulfil the basic response requirements of the standards, do not meet the accuracy requirements. Because no transfer measurements were made between laboratories, there is no way to detect similar errors in both the system under test and the reference system. Hence, the situation may be worse than reported. This has led to the recommendation that comparative measurements should be the main route for quantifying industrial impulse measuring systems

Atomic fountain of laser-cooled Yb atoms for precision measurements

We demonstrate launching of laser-cooled Yb atoms in a cold atomic fountain. Atoms in a collimated thermal beam are first cooled and captured in a magneto-optical trap (MOT) operating on the strongly allowed S-1(0) -> P-1(1) transition at 399 nm (blue line). They are then transferred to a MOT on the weakly allowed S-1(0) -> P-3(1) transition at 556 nm (green line). Cold atoms from the green MOT are launched against gravity at a velocity of around 2.5 m/s using a pair of green beams. We trap more than 107 atoms in the blue MOT and transfer up to 70% into the green MOT. The temperature for the odd isotope Yb-171 is similar to 1 mK in the blue MOT, and reduces by a factor of 40 in the green MOT.

Radio interference measurements on a ceramic disc insulator string with field reduction electrode

This paper presents a laboratory study of the discharge radio noise generated by ceramic insulator strings under normal conditions. In the course of study, a comparison on the performance of two types of insulator strings under two different conditions was studied namely (a) normal disc insulators in a string and (b) disc insulators integrated with a newly developed field reduction electrode fixed to the disc insulator at the pin junction. The results obtained during the study are discussed and presented.

New twelve node serendipity quadrilateral plate bending element based on Mindlin-Reissner theory using Integrated Force Method

The Integrated Force Method (IFM) is a novel matrix formulation developed for analyzing the civil, mechanical and aerospace engineering structures. In this method all independent/internal forces are treated as unknown variables which are calculated by simultaneously imposing equations of equilibrium and compatibility conditions. This paper presents a new 12-node serendipity quadrilateral plate bending element MQP12 for the analysis of thin and thick plate problems using IFM. The Mindlin-Reissner plate theory has been employed in the formulation which accounts the effect of shear deformation. The performance of this new element with respect to accuracy and convergence is studied by analyzing many standard benchmark plate bending problems. The results of the new element MQP12 are compared with those of displacement-based 12-node plate bending elements available in the literature. The results are also compared with exact solutions. The new element MQP12 is free from shear locking and performs excellent for both thin and moderately thick plate bending situations.

Thermodynamic properties of strontium titanates Sr2TiO4, Sr3Ti2O7, Sr4Ti3O10, and SrTiO3

The chemical potentials of SrO in two-phase fields (TiO2 + SrTiO3) (SrTiO3 + Sr4Ti3O10) (Sr4Ti3O10 + Sr3Ti2O7) and (Sr3Ti2O7 + Sr2TiO4) of the pseudo-binary system (SrO + TiO2) have been measured in the temperature range (900 to 1250) K relative to pure SrO as the reference state using solid-state galvanic cells incorporating single crystal SrF2 as the electrolyte The cells were operated under pure oxygen at ambient pressure The standard Gibbs free energies of formation of strontium titanates SrTiO3 Sr4Ti3O10 Sr3Ti2O7 and Sr2TiO4 from their component binary oxides were derived from the reversible electromotive force (EMF) of the cells For the formation of the four compounds from their component oxides TiO2 with rutile structure and SrO the standard Gibbs free energy changes are given by Delta G((ox))(SrTiO3) +/- 89/(J mol(-1)) = -121878 + 3 881(T/K) Delta G((ox))(Sr4Ti3O10) +/- 284/(J mol(-1)) = -409197 + 14 749(T/K) Delta G((ox))(Sr3Ti2O7) +/- 190/(J mol(-1)) = -285827 + 10 022(T/K) Delta G((ox))(Sr2TiO4) +/- 110/(J mol(-1))= -159385 + 3 770(T/K) The reference state for solid TiO2 is the rutile form The results of this study are in good agreement with Gibbs free energy of formation data reported in the literature for SrTiO3 but differ significantly with data for Sr4Ti3O10 For Si3Ti2O7 and Si2TiO4 experimental measurements are not available in the literature for direct comparison with the results obtained in this study (C) 2010 Elsevier Ltd All rights reserved