Adiabatic kinetic studies of the cytidine/acetic anhydride reaction by utilizing temperature versus time data

It is possible to predict the kinetics of a reaction by using temperature versus time data under adiabatic conditions. This method was used for the cytidine/acetic anhydride reaction using a RC1 Mettler Reaction Calorimeter. The authenticity of the experimental adiabatic system was verified by determining the kinetic parameters of a known reaction (hydrolysis of acetic anhydride) and comparing them to literature values. For example, the average experimental activation energy, heat of reaction, and ln k0 values for the hydrolysis of acetic anhydride were 11.2 ±.5 kcal/gmole, -14.4 ± .2 kcal/gmole, and 12.74 ± .94 sec-1, respectfully, while the average literature values were 12.0 ± 2.4 kcal/gmole, -14.3 ± .3 kcal/qmole, and 11.56 ± 1.47 sec-1, respectfully. The reaction was first order. The cytidine/acetic anhydride reaction (unknown system) was subjected to the same adiabatic analysis and the average experimental activation energy, heat of reaction, and ln k0 values were 13.3 ± .2 kcal/gmole, -10.5 ± .1 kcal/gmole, and 15.68 ± .34 L/(gmole sec), respectfully. To further verify the results for the unknown system,three isothernal runs were executed and sanples were analyzed for concentration by High Pressure Liquid Chronatography (HPLC). The concentration-time data were analyzed and an Arrhenius Plot was constructed yielding an activation energy of 13.2 kcal/ginole and a ln k0 value of 15.14 L/(gTnole sec). The reaction was second order

A new density-dependent mixing rule for equations of state

A general procedure for the development of density-dependent mixing rules is demonstrated. This method is used to obtain a density-dependent local-composition mixing rule based on an extention of the work of Knox et al (1984). The resulting expression is tested with the Soave-Redlich-Kwong equation of state. Results for normal and cryogenic vapor-liquid systems for both one-parameter and three-parameter versions of the mixing rule are compared with results using the classical mixing rules

Effect of metallurgical structure and properties on adhesion and friction behavior of cobalt alloys

The metallurgical structure and some of the mechanical properties of two cobalt alloys, cobalt-50% iron and cobalt-25% molybdenum-10% chromium, were determined under various heat treated conditions. The mechanical properties of the bcc disordered Co-50Fe alloy, which was found to be very brittle, indicated an exceedingly low fracture strength, low hardness, and very weak grain boundary strength. Ordering by suitable heat treatment only produced a more brittle material with a lower fracture strength and a slightly higher hardness value. Work hardening was found to produce a finer grain structure and a greater grain boundary strength. Tensile properties were examined. It was found that the Co-25Mo-10Cr alloy was difficult to place in the alpha Co solid solution condition, which limited the ability to use precipitation as a hardening reaction. Over two hundred adhesion cycles from zero contact load, to maximum load, to fracture were conducted between couples for each of the above alloys in an ultrahigh vacuum system which would permit the sample surfaces to be cleaned of all contaminant layers. In the Co-50Fe case, the calculated fracture stress from the adhesion tests showed values in the range of 80 to 150 k.s.i., which is about ten times greater than the values from tension tests

Protective oxide films. Progress report

Resistance relaxation, thermogravimetry, transport, and EPR were used to study the growth of protective NiO films on nickel. (DLC