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41.
The X-ray crystal structures of a series of lithium quinolates – lithium 8-hydroxyquinolinate (Liq), lithium 2-methyl-8-hydroxyquinolinate (MeLiq), and 2-phenyl-8-hydroxquinolinate (PhLiq), are compared. The substitution at the 2-position of the 8-hydroxyquinoline ligand has significant impact on the aggregation of the lithium complex in the crystalline state. Liq and MeLiq molecules crystallize as hexamers, whereas PhLiq crystallizes as a tetramer. The possible influence of crystal-packing forces on the preferred cluster structure was probed using density functional theory calculations on a systematically varied set of Liq, MeLiq, and PhLiq clusters. For Liq and MeLiq, the observed structures match the most stable computed structures. In the PhLiq case, the observed tetrameric structure is computed to be less stable (+1.2 kcal/mol/monomer) than the lowest energy structure, a hexamer. In this case, solid-state effects probably outweigh small differences in cluster stability. 相似文献
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Anthony D. Appelhans John E. Olson David A. Dahl Michal B. Ward Troy A. Robinson James E. Delmore 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(2):207-209
A new isotope separator has been designed, constructed, and put into routine operation for separation of 133Xe providing a major advancement and significant cost reduction in preparation of this radioactive isotope. The design features and advantages are discussed that expedite high purity separation of relatively small quantities of this isotope. These advantages could be easily used to expedite separation of other shorter-lived radioactive isotopes. 相似文献
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K.R. Jackson J.C. Borba M. Meija D.L. Mills D.M. Haverstick K.E. Olson R. Aranda G.T. Garner E. Carrilho J.P. Landers 《Analytica chimica acta》2016
We report the development of a disposable polyester toner centrifugal device for semi-automated, dynamic solid phase DNA extraction (dSPE) from whole blood samples. The integration of a novel adhesive and hydrophobic valving with a simple and low cost microfabrication method allowed for sequential addition of reagents without the need for external equipment for fluid flow control. The spin-dSPE method yielded an average extraction efficiency of ∼45% from 0.6 μL of whole blood. The device performed single sample extractions or accommodate up to four samples for simultaneous DNA extraction, with PCR-readiness DNA confirmed by effective amplification of a β-globin gene. The purity of the DNA was challenged by a multiplex amplification with 16 targeted amplification sites. Successful multiplexed amplification could routinely be obtained using the purified DNA collected post an on-chip extraction, with the results comparable to those obtained with commercial DNA extraction methods. This proof-of-principle work represents a significant step towards a fully-automated low cost DNA extraction device. 相似文献
47.
Eric Johnsen Johan Larsson Ankit V. Bhagatwala William H. Cabot Parviz Moin Britton J. Olson Pradeep S. Rawat Santhosh K. Shankar Bj?rn Sj?green H.C. Yee Xiaolin Zhong Sanjiva K. Lele 《Journal of computational physics》2010,229(4):1213-1237
Flows in which shock waves and turbulence are present and interact dynamically occur in a wide range of applications, including inertial confinement fusion, supernovae explosion, and scramjet propulsion. Accurate simulations of such problems are challenging because of the contradictory requirements of numerical methods used to simulate turbulence, which must minimize any numerical dissipation that would otherwise overwhelm the small scales, and shock-capturing schemes, which introduce numerical dissipation to stabilize the solution. The objective of the present work is to evaluate the performance of several numerical methods capable of simultaneously handling turbulence and shock waves. A comprehensive range of high-resolution methods (WENO, hybrid WENO/central difference, artificial diffusivity, adaptive characteristic-based filter, and shock fitting) and suite of test cases (Taylor–Green vortex, Shu–Osher problem, shock-vorticity/entropy wave interaction, Noh problem, compressible isotropic turbulence) relevant to problems with shocks and turbulence are considered. The results indicate that the WENO methods provide sharp shock profiles, but overwhelm the physical dissipation. The hybrid method is minimally dissipative and leads to sharp shocks and well-resolved broadband turbulence, but relies on an appropriate shock sensor. Artificial diffusivity methods in which the artificial bulk viscosity is based on the magnitude of the strain-rate tensor resolve vortical structures well but damp dilatational modes in compressible turbulence; dilatation-based artificial bulk viscosity methods significantly improve this behavior. For well-defined shocks, the shock fitting approach yields good results. 相似文献
48.
Richard F. Smith Laurie A. Olson William J. Ryan Karen J. Coffman Julienne M. Galante Timothy S. Wojdan 《合成通讯》2013,43(5):585-596
A simple, efficient procedure for the conversion of phenylhydrazine to 1-alkyl-1-phenylhydrazines via base-promoted hydrolysis of 1-alkyl-3-amino-4,5-dihydro-1-phenyl-1H-pyrazolium iodides (2) is described. N1, N1-disubstituted hydrazones of trans-cinnamamide and acrylamide are obtained by Hofmann-type ring openings of 1,1 -disubstituted-3-amino-4,5-dihydro-5-phenyl (or 5-unsubstituted) -1H-pyrazolium halides (5, 7). 相似文献
49.
John A. Kyndt Terry E. Meyer Kenneth T. Olson Jozef Van Beeumen Michael A. Cusanovich 《Photochemistry and photobiology》2013,89(2):349-360
Of the 10 photoactive yellow protein (PYPs) that have been characterized, the two from Rhodobacter species are the only ones that have an additional intermediate spectral form in the resting state (λmax = 375 nm), compared to the prototypical Halorhodospira halophila PYP. We have constructed three chimeric PYP proteins by replacing the first 21 residues from the N‐terminus (Hyb1PYP), 10 from the β4–β5 loop (Hyb2PYP) and both (Hyb3PYP) in Hhal PYP with those from Rb. capsulatus PYP. The N‐terminal chimera behaves both spectrally and kinetically like Hhal PYP, indicating that the Rcaps N‐terminus folds against the core of Hhal PYP. A small fraction shows dimerization and slower recovery, possibly due to interaction at the N‐termini. The loop chimera has a small amount of the intermediate spectral form and a photocycle that is 20 000 times slower than Hhal PYP. The third chimera, with both regions exchanged, resembles Rcaps PYP with a significant amount of intermediate spectral form (λmax = 380 nm), but has even slower kinetics. The effects are not strictly additive in the double chimera, suggesting that what perturbs one site, affects the other as well. These chimeras suggest that the intermediate spectral form has its origins in overall protein stability and solvent exposure. 相似文献
50.
A. Madani S. Zeinoddini S. Varahmi H. Turnbull A. B. Phillion J. A. Olson D. M. Martinez 《Cellulose (London, England)》2014,21(3):2023-2031
A methodology for producing a low density cellulose-based foam has been developed by combining a surfactant with pulp, mixing at high velocity to entrain air, and then drying in a non-restrained fashion. The structure of the foam, characterized through optical microscopy and X-ray computed tomographic microscopy, consists of pulp fibres in random orientations surrounding air bubbles along with large void spaces. Through careful design of experiments, the effect of fibre type, length distribution, surfactant, and air content on the mechanical behavior and permeability of the foam material was investigated. The results indicate that foamed cellulose materials can be produced at a strength of one-half the tensile strength of a standard handsheet, but having a relative density of only one percent. No chemical additives were used to enhance the strength of these samples as the properties of the foam material are enhanced simply through variation of the process parameters. Thus, a strong cellulose-based foam, with a density as low as 10 mg/cm3, can be fabricated using standard papermaking infrastructure and hence at low cost. 相似文献