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1.
The conformational preferences of nicotine in three protonation states and in the gas phase as well as aqueous solution are investigated using several computational procedures. Conformational aspects emphasized are N-methyl stereochemistry, relative rotation of the pyridine and pyrrolidine rings, and pyrrolidine ring conformation. All methods consistently predicted that the N-methyl trans species are most stable for all protonation states in both gas phase and in water. However, the cis/trans energy gap is significantly reduced in water. Additionally, the two pyridine ring rotamers, which are energetically equivalent in the gas phase, experience different solvation energies in water. 相似文献
2.
Two microbial cultures—ML-13 (aCandida sp.) and LSC (a fungal isolate from the University of Arkansas)—have been employed in the direct liquefaction of Louisiana
lignite. Lignite samples were pretreated with nitric acid and microbial culture broths at elevated temperatures and pressures.
Subsequent treatment with active cultures and culture derivatives resulted in significant solubilization of the lignite. Up
to 50% liquefaction of pretreated coal (20% HNO3 at ambient temperature and pressure) was observed in 4 d with ML-13 cultures, whereas almost 80% liquefaction occurred in
a similar time period when exposing pretreated lignite to an autoclaved, cell-free culture broth. 相似文献
3.
Madhukar G. R. Elmore B. B. Huckabay H. K. 《Applied biochemistry and biotechnology》1996,57(1):243-251
Applied Biochemistry and Biotechnology - Enriched culture techniques have been used to isolate microbial cultures exhibiting growth on synthesis gas components. Three rod-shaped, gram-positive... 相似文献
4.
5.
Bentley H. Brissaud I. Elmore D. Gove H. Ma X. Z. 《Zeitschrift für Physik A Hadrons and Nuclei》1983,311(3):243-244
Zeitschrift für Physik A Hadrons and nuclei - Four groundwater samples from the Stripa site have been analysed by accelerator mass spectrometry at the University of Rochester. The36Cl... 相似文献
6.
7.
S. Boag E. Babcock K.H. Andersen M. Becker T.R. Charlton W.C. Chen R.M. Dalgliesh S.D. Elmore C.D. Frost T.R. Gentile R. Lopez Anton S.R. Parnell A.K. Petoukhov M.W.A. Skoda T. Soldner 《Physica B: Condensed Matter》2009,404(17):2659-2662
We discuss the development and characterisation of a new in situ spin exchange optical pumping (SEOP) based 3He neutron spin filter polarisation device. We present results from a recent test of the prototype system developed with the Institut Laue-Langevin. The polariser was installed on the polarised reflectometer CRISP at ISIS in the analyser position. The 3He was pumped continuously in situ on the beamline. The system also integrated a 3He adiabatic fast passage spin flipper that allowed reversal of the 3He and therefore neutron polarisation state, allowing for measurement of all four polarisation cross-sections. The system was run for a number of days reaching a 3He polarisation of 63%. 相似文献
8.
The volatile aroma compounds in cooked pork were examined using solid-phase microextraction (SPME). Two SPME fibres coated with different stationary phases were used simultaneously to collect aroma compounds from the headspace above the pork. One fibre was coated with 75 microm. Carboxen-polydimethylsiloxane and the other was coated with 50/30 microm divinylbenzene-Carboxen on polydimethylsiloxane. After extraction, the two fibres were desorbed in the injection port of a gas chromatograph sequentially, so that the aroma compounds from both of the fibres could be analysed in one gas chromatogram. This procedure resulted in a chromatogram containing a more complete aroma profile for cooked pork than the chromatograms from either of the fibres on their own. Thirty-six compounds were identified in cooked pork for the first 相似文献
9.
Klasson K. T. Elmore B. B. Vega J. L. Ackerson M. D. Clausen E. C. Gaddy J. L. 《Applied biochemistry and biotechnology》1990,24(1):857-873
Applied Biochemistry and Biotechnology - Liquid and gaseous fuels may be produced biologically from coal by the indirect conversion of coal synthesis gas. Methane has been produced from synthesis... 相似文献
10.
Park CM Oie T Petros AM Zhang H Nimmer PM Henry RF Elmore SW 《Journal of the American Chemical Society》2006,128(50):16206-16212
One of the primary objectives in the design of protein inhibitors is to shape the three-dimensional structures of small molecules to be complementary to the binding site of a target protein. In the course of our efforts to discover potent inhibitors of Bcl-2 family proteins, we found a unique folded conformation adopted by tethered aromatic groups in the ligand that significantly enhanced binding affinity to Bcl-XL. This finding led us to design compounds that were biased by nonbonding interactions present in a urea tether to adopt this bioactive, folded motif. To characterize the key interactions that induce the desired conformational bias, a series of substituted N,N'-diarylureas were prepared and analyzed using X-ray crystallography and quantum mechanical calculations. Stabilizing pi-stacking interactions and destabilizing steric interactions were predicted to work in concert in two of the substitution patterns to promote the bioactive conformation as a global energy minimum and result in a high target binding affinity. Conversely, intramolecular hydrogen bonding present in the third substitution motif promotes a less active, extended conformer as the energetically favored geometry. These findings were corroborated when the inhibition constant of binding to Bcl-XL was determined for fully elaborated analogues bearing these structural motifs. Finally, we obtained the NMR solution structure of the disubstituted N,N'-diarylurea bound to Bcl-XL demonstrating the folded conformation of the urea motif engaged in extensive pi-interactions with the protein. 相似文献