THE HEAT CAPACITY AND THERMODYNAMIC PROPERTIES OF THE THERMAL TRANSITIONS OF STRONTIUM HEXAAMMINE

The heat capacity, transition temperatures and the corresponding enthalpy changes of a 6.51 MPM Sr(NH3)6/NH3 system have been measured from 80 K to 190 K by means of adiabatic calorimetry. From 85 K to 145 K the heat capacity of the solid ammine is approximately linear and displays a modest pretransition increase from [MATH]145 K to 175.74 K where a solid-solid transition occurs for which [MATH]H = 1181 ± 10 cal mole-1 of Sr(NH3)6 and [MATH]Str = 7.61 cal mole-1 K-1 after correction for a pretransition effect of 0.89 cal mole-1 K-1. From [MATH]80 K to [MATH]140 K our Cp data are about midway between others' results reported earlier for two different samples of the hexaammine which differed [MATH]40% at 100 K. The enthalpy change we have observed is [MATH] double that reported by others using differential thermal analysis. For the eutectic transition, we estimate [MATH]Str [MATH] 5.28 kcal mole-1 K-1 of hexaammine melting. An exploratory investigation of the effect of ND3 substitution for NH3 in the hexaammine indicated that the S-S transition was elevated 6.34 K from 175.74 K to 182.08 K ; and that the eutectic transition was increased by 5.17 K from 185.37 K to 190.54 K. The [MATH]Str for the S-S transition, which we take to be an order-disorder transition, is in line with [MATH]Str for similar transitions that occur in the M(NH3)6I2 salts in which "revised" [MATH]Str's are [MATH] Rln 32 which also approximates the experimental [MATH]S for Ca(NH3)6I2 as well as for Sr(NH3)6 - both of which contain comparably large M+2

International technology the international agricultural research centers

64 páginas.La investigación agrícola tropical, durante mucho tiempo la cenicienta de los servicios de apoyo agrícola, ha estado recibiendo una atención cada vez mayor durante las dos últimas décadas. Esto no quiere decir que sea un fenómeno nuevo la tropical a) la agricultura; la investigación salvó la industria del algodón en Gezira en la década de 1930 y sentó las bases para la competitividad de la industria del caucho natural con los sintéticos de la década de 1950; ha traído incrementos de rendimiento muy significativos en cultivos tan diversos como diez, 011 palma y cacao. Sin embargo, había tenido un impacto relativamente pequeño en los cultivos alimentarios, aunque algunos descubrimientos, como los del virus del mosaico de la yuca y el del maíz del virus del rayado, formaron la base de los programas de mejoramiento exitosos de los centros internacionales

PATTERNS AND PREDICTORS OF ECONOMIC DEVELOPMENT POWER IN LOCAL GOVERNMENT: A POLICY PERSPECTIVE ON ISSUES IN ONE STATE

The purpose of this paper is to examine patterns and predictors of local government economic development in one state. The approach uses data from local governments and various statistical analyses to derive common dimensions of local government power and examine predictors of these dimensions. The results suggest that state policies on development strat-egies have to be developed and effectively exercised to increase the power of the local government in the multiple constituent network. Copyright 1987 by The Policy Studies Organization.