Permanence criteria for semi-free profinite groups

We introduce the condition of a profinite group being semi-free, which is more general than being free and more restrictive than being quasi-free. In particular, every projective semi-free profinite group is free. We prove that the usual permanence properties of free groups carry over to semi-free groups. Using this, we conclude that if k is a separably closed field, then many field extensions of k((x,y)) have free absolute Galois groups.Comment: 24 page

Endocrine Disorders as a Contributory Factor to Neoplasia in SJL/J Mice

We studied the endocrine status of SJL/J mice. Light and electron microscopy revealed that the adenohypophyses of both sexes became progressively infiltrated with an abnormal number of gonadotropinproducing cells that probably secreted large amounts of luteotropic hormone. The ovaries had numerous large corpora lutea even in animals over 1 year of age with reticulum cell neoplasms. The adrenal cortexes of female mice showed no regression of the reticular zone. In accordance with the anomalous condition of the adenohypophysis and ovary, females had abnormal estrous cycles, with prolonged diestrus and consequent reduction in fertility. These data were discussed in the context of hormone environment versus onset of systemic neoplastic disease and the relationship between hormone dependence and leukemic virus expressio

Theoretical Analysis of Metal Hydride Electrodes: Studies on Equilibrium Potential and Exchange Current Density

A theoretical model for the metal hydride electrode has been developed assuming that hydrogen diffusion in the alloy and charge-transfer at the surface control the discharge process. Theoretical equations for the dependence of equilibrium potential and exchange current density on the surface hydrogen concentration have been derived. These parameters have been used to correlate experimental data with the theoretical electrode discharge model. Analysis of both the experimental and theoretical discharge curves reveals a potential plateau determined by the magnitude of the interactions between the hydrogen in the alloy and the unhydrided metal. Neglecting these hydrogen-metal site interactions results in simulations predicting the electrode potential varying over the entire duration of discharge. The results also indicate that utilization of the electrode is controlled by the rate of hydrogen diffusion in the electrode and by the alloy particle size. Kinetic resistance at the surface is a determining factor of the polarization losses of the electrode. The variation of equilibrium potential and exchange current density with the state of charge has been characterized experimentally. These results are compared with the model predictions, and good agreement is seen

Studies on Electroless Cobalt Coatings for Microencapsulation of Hydrogen Storage Alloys

LaNi4.27Sn0.24 alloy was microencapsulated with cobalt by electroless deposition from an alkaline hypophosphite bath. Discharge curves of the encapsulated alloy indicate an additional contribution to the capacity arising from the cobalt on the surface. Studies on cobalt thin films reveal the presence of adsorbed hydrogen in cobalt. The amount of hydrogen adsorbed was observed to increase with time of cathodic polarization and to reach a maximum. Polarization techniques have been used to characterize the cobalt-plated alloy as a function of state of charge. The equilibrium potential of the microencapsulated electrode at low hydrogen concentration is determined by the potential of the cobalt coating on the surface

OPTIMIZATION OF THE CATHODE LONG TERM STABILITY IN MOLTEN CARBONATE FUEL CELLS: EXPERIMENTAL STUDY AND MATHEMATICAL MODELING

The cathode materials for molten carbonate fuel cells (MCFCs) must have low dissolution rate, high structural strength and good electrical conductivity. Currently available cathodes are made of lithiated NiO which have acceptable structural strength and conductivity. However a study carried out by Orfeld et al. and Shores et al. indicated that the nickel cathodes dissolved, then precipitated and reformed as dendrites across the electrolyte matrix. This results in a decrease in cell utilization and eventually leads to shorting of the cell. The solubility of NiO was found to depend upon the acidity/basicity of the melt (basicity is directly proportional to log P{sub CO2}), carbonate composition, H{sub 2}O partial pressure and temperature. Urushibata et al. found that the dissolution of the cathode is a primary life limiting constraint of MCFCs, particularly in pressurized operation. With currently available NiO cathodes, the goal of 40,000 hours for the lifetime of MCFC appears achievable with cell operation at atmospheric pressure. However, the cell life at 10 atm and higher cell pressures is in the range between 5,000 to 10,000 hours. The overall objective of this research is to develop a superior cathode for MCFC's with improved catalytic ability, enhanced corrosion resistance with low ohmic losses, improved electronic conductivity. We also plan to understand the corrosion processes occurring at the cathode/molten carbonate interface. The following cathode materials will be subjected to detailed electrochemical, performance, structural and corrosion studies. (i) Passivated NiO alloys using chemical treatment with yttrium ion implantation and anodic yttrium molybdate treatment; (ii) Novel composite materials based on NiO and nanosized Ce, Yt, Mo; (iii) Co doped LiNiO{sub 2} LiNiO{sub 2} doped with 10 to 20% Co (LiCo{sub 0.2}NiO{sub 2}) and NiO cathodes; and (iv) CoO as a replacement for NiO. Passivation treatments will inhibit corrosion and increase the stability of the cathode at high temperatures. Deposition of refractory metals (Mo, W, Li{sub 2}NiCrO{sub 4}) will impart stability to the cathode at high temperatures. Further it will also increase the electrocatalytic activity and corrosion resistance of the cathode. Doping with Co will decrease the alloy dissolution and increase the cycle life of the cathode. In the reporting period the oxidation behavior of Ni and Co in Li + Na carbonate eutectic was investigated under oxidizing environment using cyclic voltammetry, electrochemical impedance spectroscopy and potentiodynamic technique. The open circuit potential was monitored as a function of time in order to evaluate the material's reactivity in the melt