Biochemical analysis of wood and wood products by pyrolysis-mass spectrometry and multivariate analysis

Pyrolysis—mass spectrometry in combination with discriminant analysis and a newly development non-supervised mixture analysis approach is shown to provide valuable information about the biochemical composition of wood and wood products. The application of this technique to the chemotaxonomy of sagebrush (Artemisia) species as well as to the quality control of wood pulping processes is discussed. With regard to the latter application strong correlations are found between classical lignin and xylan determinations and direct pyrolysis—mass spectrometric analysis results.     

An efficient implementation of the direct-SCF algorithm on parallel computer architectures

Summary The development and implementation of a parallel direct self consistent field (SCF) Hartree-Fock algorithm, with gradients and random phase approximation solutions is presented. Important details of the structure of the parallel version of DISCO and preliminary results for calculations using the Concurrent Supercomputing Consortium Intel Touchstone Delta parallel computer system are reported. The data show that the algorithms are efficiently parallelized and that throughput of a one processor CRAY X-MP is reached with about 16 nodes on the Delta. The data also indicate sequential code which was not a bottleneck on traditional supercomputers, can become time critical on parallel computers.This work was performed under the auspices of the Office of Basic Energy Sciences, Division of Chemical Sciences, U.S. Department of Energy, under contract DE-AC06-76RLO 1830 for Pacific Northwest Laboratory which is operated by Battelle Memorial Institute for the U.S. Department of Energy.     

Rearrangement of pyrrolines derived from the Birch reduction of electron-deficient pyrroles: radical ring-expansion to substituted tetrahydropyridines

Access to the synthetically important tetrahydropyridine motif has been achieved by radical rearrangement of pyrrolines obtained from the Birch reduction of electron-deficient pyrroles.     

A parallel version of ARGOS: A distributed memory model for shared memory UNIX computers

Summary A distributed memory programming model was used in a fully parallel implementation of theab initio integral evaluation program ARGOS (R. Pitzer (1973)J. Chem. Phys. 58:3111), on shared memory UNIX computers. The method used is applicable to many similar problems, including derivative integral evaluation. Only a few lines of the existing sequential FORTRAN source required modification. Initial timings on several multi-processor computers are presented. A simplified version of the programming tool used is also presented, and general consideration is given to the parallel implementation of quantum chemistry algorithms.Work performed at Argonne National Laboratory under the auspices of the Division of Chemical Sciences, Office of Basic Energy Sciences, U.S. Department of Energy under contract W-31-109-Eng-38. Pacific Northwest Laboratory is operated for the U.S. Department of Energy by Battelle Memorial Institute under contract DE-AC06-76RLO 1830     

Proton Nuclear Magnetic Resonance Measurements of 2′-Aminodeoxyuridylyl-3′,5′-Deoxyuridine

A dideoxyribonucleotide, 2′-amino-2′-deoxyuridylyl 3′,5′-deoxyuridine, containing an unsual base (2′-amino-2′-deoxyuridine) that isresistant to nucleases was investigated by ′H NMR. The pK_a of the protonation of the amino group (5.8) was determined by profiles of chemical shifts of protons in the vicinity of amino group versus pH. However, protonation of the amino group has little effect on the conformation of the dimer, assumed to be B-form DNA. This conclusion is drawn from the chemical shift data and coupling constants of H₁-H₂. Thus, 2′-amino-2′-deoxyuridine can be used in antisense and anticode oligonucleotides.     

Yeast cells long-term interaction with asbestos fibers

Saccharomyces cerevisiae was supported on chrysotile, crocidolite and lixiviated chrysotile. Samples of the supported cells and free cells were observed by confocal laser scanning microscopy. After 30 days, the free cells showed no viability when stored at 30 °C, and a viability of 40% when stored at 4 °C. Supported cells stored at 30 °C were more viable than the free cells at early times, but showed no viability after 30 days. Samples stored at 4 °C showed that the adhered cells are more viable than the free cells, up to 30 days. Cells supported on chrysotile and lixiviated chrysotile had 80% viability, and on crocidolite 70% viability. Scanning electron microscopy showed that cells supported on lixiviated chrysotile are fully covered by the support, but crocidolite fibers adhere less, since they are stiffer. Fermentation experiments performed after 3 years storage showed that four from the five lixiviated chrysotile samples and one of the three crocidolite samples were active. In all cases, a delay time for the onset of fermentation was observed indicating a state of latency.     

Chemical interactions between aqueous and organic phases in a reactive extraction process

Partitioning of lactic acid between aqueous phase and kerosene containing trin-octyl phosphine oxide (TOPO) as a reactive agent was measured and analyzed in terms of an association model between lactic acid and TOPO. Equilibrium association was calculated to involve 1.1 mol of lactic acid/mol of TOPO.³¹P-NMR and FTIR analyses found no evidence of covalent bond formation between lactic acid and TOPO in solutions in kerosene, and pointed to hydrogen bond formation between the two chemicals. In a hydrophobic, microporous, hollow-fiber-membrane module, the simultaneous presence of lactic acid, TOPO, and the back-extractant NaOH resulted in drastic membrane fouling as evidenced by the loss of kerosene flux through the membrane. The membrane could be restored back to the original kerosene flux after extensive washing.

     

Gel-state NMR investigation of crosslinked poly(methy1 methacrylate) incorporating 13C labeled ethylene glycol dimethacrylate

¹³C labeled ethylene glycol dimethacrylate (EGDMA) was used to form labeled crosslinked PMMA and model ¹³C labeled pendant double bond copolymers. Solution NMR was possible on solvent-swollen samples containing less than 0.5% by weight EGDMA. Spectra confirm significant amounts of singly reacted EGDMA in fully polymerized networks. Peaks arising from the two most likely stereochemical triads (syndi- and heterotactic) were identified but no evidence of cyclic species was observed. Labeled EGDMA allowed observation of the crosslink site at concentrations as low as 0.02 wt-% EGDMA.