Digital Commons Network^™

Polyacrylamide In Glycerol Solutions From An Atomistic Perspective Of The Energetics, Structure, And Dynamics, Scott D. Hopkins, Gideon K. Gogovi, Eric Weisel, Robert A. Handler, Estela Blaisten-Barojas

VMASC Publications

All-atom molecular dynamics is used to investigate the structural, energetic, and dynamical properties of polyacrylamide (PAM) oligomers of different lengths solvated in pure glycerol, a 90:10 glycerol–water mixture, and pure water. We predict that the oligomers’ globular structure is obtained only when the modeling strategy considers the solvent as a continuous background. Meanwhile, for all-atom modeled solvents, the glycerol solutions display a strong tendency of trapping the oligomers in instantaneous elongated random coiled structures that remain locked-in over tens of nanoseconds. In pure water, the oligomers acquire considerably shorter random coiled structures of increased flexibility. The all-atom force field, generalized …

Atlas Of Experimental And Theoretical High Temperature Methane Cross Sections From T = 295 To 1000k In The Near-Infrared, Andy Wong, Peter F. Bernath, Michael Rey, Andrei V. Nikitin, Vladimir G. Tyuterev

Chemistry & Biochemistry Faculty Publications

Spectra of hot methane were recorded using a tube furnace and a high-resolution Fourier transform spectrometer. We obtained experimental absorption spectra in the 1.85-1.11 μm near-infrared region at eight temperatures ranging from 295 K up to 1000 K. We have converted these into an atlas of absorption cross sections at each temperature for the methane tetradecad, icosad and triacontad polyads, excluding some spectral intervals either strongly contaminated by water or due to baseline fringes. On the theoretical side, the spectra were simulated from the ab initio-based Reims-Tomsk TheoReTS line list for the same experimental conditions. This line list has been …

Ace-Fts Observations Of Pyrogenic Trace Species In Boreal Biomass Burning Plumes During Bortas, K. A. Tereszchuk, G. G. Abad, C. Clerbaux, J. Hadji-Lazaro, D. Hurtmans, P. F. Coheur, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

To further our understanding of the effects of biomass burning emissions on atmospheric composition, the BORTAS campaign (BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites) was conducted on 12 July to 3 August 2011 during the boreal forest fire season in Canada. The simultaneous aerial, ground and satellite measurement campaign sought to record instances of boreal biomass burning to measure the tropospheric volume mixing ratios (VMRs) of short- and long-lived trace molecular species from biomass burning emissions. The goal was to investigate the connection between the composition and the distribution of these pyrogenic outflows and …

Development And Application Of A Gg-Irms Reductive Pyrolysis Reactor Interface For The Δ34S Determination Of Sulfur In Individual Organic Compounds, N. Deborah Hewlett

Chemistry & Biochemistry Theses & Dissertations

The incorporation of sulfur into sedimentary organic matter is an important aspect of organic carbon preservation. A better understanding of the sulfur cycle and the formation of organo-sulfur compounds are necessary if we are to better understand the interaction of biogeochemical cycles of C, N, O, H. and S. Currently, the determination of ³⁴S/³²S in organic matter is limited to bulk organic samples. The sulfur isotopic analysis of individual organo-sulfur compounds within the sediments should allow for a more complete understanding of the sulfur cycle and the processes which lead to sulfur incorporation into organic matter. This …

Meso-1, 2-Bis (Methylazo)-1, 2-Diphenylethane, Craig A. Bayse, Barry K. Carpenter, Rudy L. Luck

Chemistry & Biochemistry Faculty Publications

The title compound, meso-1,2-bis(methyldiazenyl)-1,2-diphenylethane, C16H18N4, is arranged in a disordered manner around an inversion point. The N—N atom distances in the azo group of 1.192 (8) and 1.195 (8) Å, and the C—C atom distances in the ethylene moiety at 1.512 (8) and 1.503 (8) Å in the two models [refined to 51.7 (6) and 48.3 (6)% occupancies] were not significantly different.

The Regioselective 3-Alkylation Of Piperidine, Richard Dunn Todd

Chemistry & Biochemistry Theses & Dissertations

The compounds: 3-allylpiperidine, 3-ethylpiperidine and 3-n-butylpiperidine have been synthesized by regioselectively alkylating the three position of piperidine. Piperidine was converted to N-chloropiperidine and then dehydrohalogenated to produce Δ¹-piperideine. The enamide anion was generated by adding solutions of Δ¹-piperideine to ethylmagnesium bromide or lithium diisopropylamide. Addition of alkylhalides produced 3-alkyl- Δ¹-piperideine which could be reduced or alkyllithiated to give 3-alkylpiperidines or 2,3-dialkylpiperidines respectively.

The yields of products were low and the reaction generated a continuum of mono- and di-alkylpiperidines and there was evidence that several dimeric piperideines were formed. The low yields were discussed in …

Synthesis Of Dihydroisoquinolines And Tetrahydroisoquinolines, John J. Schlager

Chemistry & Biochemistry Theses & Dissertations

Dihydroisoquinolines and tetrahydroisoquinolines are compounds which possess a variety of pharmacological activities. New easier methods of synthetic manipulations of these structures is of constant interest in the pharmaceutical industry.

This paper describes a new three step method of preparing 1-alkyl- and 1-aryl-tetrahydroisoquinolines from a tetrahydroisoquinoline. The synthesis involves the N-chlorination of tetrahydroisoquinoline followed by dehydrohalogenation with potassium superoxide. The reaction products are the dihydroisoquinolines. Overall yields range from 85-96%. The unsubstituted, 1-methyl-, and 1-phenyl-J,4-dihydroisoquinolines have been formed. Organometallation of the unsubstituted dihydroisoquinoline provides the 1-substituted tetrahydroisoquinoline. The 1-benzyl-, 1-n-butyl-, 1-ethyl-, 1-methyl-, and 1-phenyl-1,2,J,4-tetrahydroisoquinolines were prepared. The use of Grignard and …

The Occurrence And Distribution Of Methane In The Marine Environment, Larry Philip Atkinson

OES Faculty Publications

The distribution of methane in several anoxic marine environments is described. Maximum concentrations observed were μ mole CH₄-C/liter. The distribution of methane seems to follow that of sulfide. The data indicate that methane is derived from organic compounds not containing nitrogen or phosphorus and that its formation is much slower than that of sulfide.