Plasma window performance and scaling for an accelerator-based neutron source.

A "plasma window" was developed for use with a SHINE accelerator-based neutron source. In this work, the design of the plasma window is presented along with results demonstrating successful operation in deuterium over a range of aperture diameters (5-12 mm), gas flow rates (3.5 to 12.5 slm), and input powers (10-55 kW). An empirically determined relationship between the aperture diameter, deuterium gas flow rate, input power, and plasma window pressure differential is also presented.

Separation of fatty acid ester and amide enantiomers by high-performance liquid chromatography on chiral stationary phases.

The enantiomeric resolution of a series of chiral fatty acid epoxide and alpha-substituted palmitic acid analogues was examined by high-performance liquid chromatography on chiral stationary phases. The compounds were chromatographed as ester or amide derivatives on commercially available stationary phases that consisted of (R)-N-(3,5-dinitrobenzoyl)phenylglycine either covalently or ionically bonded to aminopropylsilica gel. Factors affecting separation included hydrocarbon chain length of the fatty acid, the type of substituents attached to the chiral center, the type of derivative, and column temperature. Effects of sample size, mobile phase composition, column type, and flow-rate on the resolution and separation factor values were also explored.

A high-performance liquid chromatographic method for the enantiomeric analysis of the enzymatically synthesized coenzyme A ester of 2-tetradecylglycidic acid.

The enantiomeric composition of an enzymatically synthesized sample of the coenzyme A ester of 2-tetradecylglycidic acid (TDGA-CoA) was determined by the use of high-performance liquid chromatography with a chiral stationary phase. The stationary phase was commercially available and consisted of (R)-N-(3,5-dinitrobenzoyl)phenylglycine covalently bonded to aminopropyl silica gel. Analysis was performed using the phenacyl derivative of 2-tetradecylglycidic acid (TDGA), obtained by mild hydrolysis of the TDGA-CoA followed by reaction of the extracted TDGA with phenacyl chloride. Chromatography showed the enantiomeric purity of TDGA-CoA, synthesized in a rat liver microsomal enzyme mixture over a 2-h period, to be a 15.6:1 ratio of the R:S enantiomers (88% ee). The result demonstrates the stereoselectivity of the long-chain fatty acid-coenzyme A synthetase for chiral fatty acid epoxide, TDGA.

Identification of 2-tetradecylglycidyl coenzyme A as the active form of methyl 2-tetradecylglycidate (methyl palmoxirate) and its characterization as an irreversible, active site-directed inhibitor of carnitine palmitoyltransferase A in isolated rat liver mitochondria.

Methyl-2-tetradecylglycidic acid (MeTDGA) has been hypothesized to inhibit fatty acid oxidation by irreversible, active site-directed inactivation of carnitine palmitoyltransferase A after being converted to TDGA-CoA. Using synthetic TDGA-CoA, this hypothesis has been confirmed. Assessing enzyme inhibition in an isolated rat liver mitochondrial system, TDGA-CoA (synthetic or enzyme prepared) was more potent than TDGA or MeTDGA and retained activity in the absence of CoA or Mg2+-ATP. It inhibited palmitoyl-CoA but not palmitoyl carnitine oxidation. Enzyme inactivation was exponential, stereospecific, and fast (t0.5 = 38.5 s with 100 nM (R)-TDGA-CoA). TDGA-CoA was identified as a complexing type irreversible inhibitor (Ki approximately 0.27 microM) by the double reciprocal relationship between the pseudo-first order inactivation rate and its concentration, by the inverse dependence of the second order rate constant on its concentration, and by the independence of the first order rate from the enzyme concentration. Palmitoyl-CoA, CoA, and malonyl-CoA protected the enzyme, while L-carnitine and palmitoyl-L-carnitine were without effect. [3-14C] TDGA-CoA labeled a protein, Mr = 90,000, with a time course which paralleled that of enzyme inhibition; maximum specific binding was 16 pmol/mg of mitochondrial protein.