David Whitmire

XYLANASE MOLECULAR SIZE, PULP PORE-STRUCTURE AND PULP DELIGNIFICATION

Bleaching kraft pulp with chlorine can result in toxic chlorinated species in bleach plant effluent. Removing lignin from kraft pulp with xylanase reduces chlorine required for bleaching, which, in turn, reduces toxic species in bleach plant effluent. Kraft pulp mills using xylanase pretreatment have reduced chlorine requirement for bleaching by 20 to 25% for hardwood pulp but only 10 to 15% for softwood pulp. The work reported here demonostrates that xylanase molecular size and pulp pore structure determine the amount of lignin that xylanase can remove from pulp. Using softwood pulp, xylanases wilh molecular weights of 20,000 Da, 39,000 Da, and 67,000 Da removed 48%, 39%, and 30% of lignin respectively. Mild cellulase pre-treatment of softwood pulp increased the apparent median pore size from 37A to 67A which enabled xylanase to reduce chlorine requirement for softwood pulp bleaching by 31%. The same process applied to hardwood pulp eliminated 41.8% of chlorine required for bleaching.

Molecular mechanics (MM3) parameterization for oxocarbenium ions

The physical properties of a diverse group of 12 oxocarbenium ions have been studied with ab initio calculations at the MP2/6‐31+G* level of theory. Based on theoretically derived properties such as molecular equilibrium geometry, dipole moment, and vibrational frequencies, a molecular mechanics (MM3) force field has been developed with the assistance of the programs TORSMART and MPMSR, components of our artificial parameter development and refinement method. The MM3 force field is now able to reproduce bond lengths, bond angles, moments of inertia, dipole moments, torsional energy profiles, and vibrational frequencies of oxocarbenium ions, which will allow further studies of glycoside hydrolysis and their rates of reaction.

Analysis of heart rate variability on a massively parallel processor

The K/sub 2/ entropy, and the correlation dimension are commonly used measures of chaotic activity in complex dynamic systems. The design and implementation of a massively parallel algorithm on the MasPar MP-2 for the computation of K/sub 2/ entropy and the correlation dimension is presented. The algorithm is used to compute the K/sub 2/ entropy and correlation dimension of experimental heart rate data. Experimental results on canine subjects support the claim that K/sub 2/ entropy and the correlation dimension can be used as a measure of the heart rate variability and the level of chaos present in the nonlinear dynamics underlying the heart rate data. The parallel algorithm has potential for use as a tool for cardiac health assessment and diagnosis of certain cardiac ailments.

The Effect of an Amethystic Product on Ethanol in Humans

A putative amethystic product was studied in two cohorts of human subjects. The amethystic product (Sobrietol) was applied according to the manufacturers instructions while control subjects received water in place of the Sobrietol solution. The two cohorts were challenged with 1.2 ml/lb and 1.4 ml/lb of 80 proof liquor, respectively, with subsequent breath alcohol (BrAC) measurement. In cohort 1, Sobrietol reduced the area under the BrAC curve (AUC) by 15.1% (p = 0.003) relative to controls; in cohort 2 the AUC was reduced by 12.5% (p = 0.011) relative to controls. It appears that the amethystic product Sobrietol can eliminate significantly greater ethanol than ethanol eliminated by similar controls.

Short-term metabolic ethanol tolerance in dogs.

Metabolic ethanol tolerance was studied in a cohort of five dogs with ethanol challenge repeated weekly over a 7-week period. During the 7-week period, the area under the blood alcohol versus time curve (AUC) increased slightly while the rate of ethanol elimination also increased slightly. During the repeated ethanol dosing, ethanol absorption shifted from approximately equal absorption in the stomach and intestine to three-fold more absorption in the intestine than in the stomach. The likely cause of the shift in absorption site was probably a concomitant change in gastric emptying that occurred with repeated dosing. This shift is significant since ethanol absorption in the small intestine has been shown to be over six-fold more rapid than ethanol absorption in the stomach.

A MATHEMATICAL MODEL OF SUPERCRITICAL METHYLAMINE (SCM) DELIGNIFICATION OF WOOD

Abstract An unsteady-state mathematical model describing supercritical fluid (SCF) delignification of wood in a packed bed was developed. Equations describing intraparticle supercritical methyl-amine reaction with lignin, and subsequent transport of the methylamine-lignin complex into the bulk phase were derived and solved using orthogonal collocation. Model results for the case of supercritical methylamine are presented and compared with experimental results. Simulation results correctly predicted the experimental results. Sensitivity of methylamine extraction of lignin was evaluated by varying bulk fluid velocity, mass transfer coefficient, and particle diameter. Delignification was a strong function of particle diameter and a relatively weaker function of fluid velocity and mass transfer coefficient. The Thiele modulus and Biot number showed that delignification was reaction rate limited for wood particle diameter values ≤ 0.1 cm, but delignification was limited by intra-particle mass transfer for wood...

Pharmacodynamic Response to Ro15-4513 in Ethanol Intoxicated Dogs

The interaction of Ro15-4513 (5 mg/kg) with ethanol (3 g/kg, 60%w/v bolus) in dogs was investigated. Ro15-4513 challenge 120 minutes after a single ethanol dose had no significant effect on blood ethanol concentration or heart rate. In the same experiment, (1) blood acetaldehyde concentration was elevated to more than double the control value (vehicle only, no Ro15-4513), and (2) systolic blood pressure decreased to less than 60% of control. Further investigation revealed: (1) after Ro15-4513, area under the blood acetaldehyde vs time curve was more than twofold greater (p = 0.0006) than control, and the area under the systolic blood pressure vs time curve was 76% (p = 0.0027) of control. Based on these results, we propose that an inter-relationship exists between Ro15-4513, blood acetaldehyde concentration, and systolic blood pressure in ethanol intoxicated dogs.

A Massively Parallel Algorithm for K2 Entropy Computation: Case Studies of Model Systems and in Vivo Data

Grassberger and Procaccias estimate of Kolmogorov entropy, i.e., K2 entropy (Grassberger and Procaccia, 1983), is a commonly used measure of chaos present in complex dynamic systems. The design and imple mentation of a massively parallel algorithm on the MasPar MP-2 system for the computation of K2 en tropy is presented. The parallel implementation on a 2,048-processor MasPar MP-2 system is shown to have a speedup of approximately 1,000. The parallel algo rithm for the computation of the correlation integral, in conjunction with the serial algorithm for the determi nation of an optimal scaling region in the correlation integral plot, are used as a computational tool to ana lyze the heart-rate dynamics of canine subjects intoxi cated with ethanol. Results indicate that the K 2 entropy and correlation dimension have an inverse correlation with the blood-ethanol concentration.