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991.
It is shown that the complete exceptionality condition for discontinuity waves associated with a second-order non-linear hyperbolic equation of the form
相似文献
992.
Dual emission laser induced fluorescence for direct planar scalar behavior measurements 总被引:1,自引:0,他引:1
In this paper, a new method of measuring scalar behavior in bulk aqueous fluid flows is presented. Using a simple ratiometric
scheme, laser induced fluorescence from organic dyes can be normalized so that direct measurements of a scalar in the flow
are possible. The technique dual emission laser induced fluorescence (DELIF) relies on normalizing the fluorescence emission
intensity of one dye with the fluorescence emission intensity of a second dye. Since each dye fluoresces at a different wavelength,
one can optically separate the emission of each dye. This paper contains an overview of the basic ratiometric technique for
pH and temperature measurements as well as the spectral properties of nine water soluble dyes. It also covers the three most
significant sources of error in DELIF applications. To demonstrate the technique, steady state turbulent jet mixing and temperature
fields in a thermal plume were quantified. The accuracy was camera limited at under 3% of the fluorescence ratio which corresponds
to 0.1 pH units or 1.8 °C.
Received 7 June 1996/Accepted 17 June 1997 相似文献
993.
Benzene Solubility in Ionic Liquids: Working Toward an Understanding of Liquid Clathrate Formation 下载免费PDF全文
Prof. Dr. Jorge F. B. Pereira Luis A. Flores Dr. Hui Wang Prof. Dr. Robin D. Rogers 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15482-15492
The solubility of benzene in 15 imidazolium, pyrrolidinium, pyridinium, and piperidinium ionic liquids has been determined; the resulting, benzene‐saturated ionic liquid solutions, also known as liquid clathrates, were examined with 1H and 19F nuclear magnetic resonance spectroscopy to try and understand the molecular interactions that control liquid clathrate formation. The results suggest that benzene interacts primarily with the cation of the ionic liquid, and that liquid clathrate formation (and benzene solubility) is controlled by the strength of the cation–anion interactions, that is, the stronger the cation–anion interaction, the lower the benzene solubility. Other factors that were determined to be important in the final amount of benzene in any given liquid clathrate phase included attractive interactions between the anion and benzene (when significant), and larger steric or free volume demands of the ions, both of which lead to greater benzene solubility. 相似文献
994.
Profiling of the secretome of human cancer cells: Preparation of supernatant for proteomic analysis 下载免费PDF全文
Linda Joanne Rogers Natalka Suchowerska Alamgir Khan Veronika Polaskova David Robert McKenzie 《Electrophoresis》2014,35(18):2626-2633
Secretomic analysis requires removal of serum proteins from cell‐culture media. We evaluate the proteins washed from cells prepared in bovine serum‐supplemented medium. PBS and serum‐free‐medium (SFM) were the washing solutions. A Bradford assay was used for total protein concentration and a 1D gel and LC‐MS/MS, to assign the protein to human or bovine origin. For both wash solutions, all bovine protein had been removed by the third wash, without compromising the number of living cells. Further washes reduced the number of living cells, especially when using PBS. Proteomic analysis of wash supernatant showed that SFM induced greater lysis of dead cells. Three washes were sufficient to minimize the effects on cell viability, while still removing serum proteins. Washing in SFM resulted in contamination of the wash supernatant with lysed dead cell proteins. Washed cells were incubated in SFM and exposed to ionizing radiation. Analysis of the supernatant showed an increase in human cytoplasmic, plasma membrane, and nuclear protein following irradiation. Secreted proteins were also detected, but in smaller quantities. The significance of these findings extend to in vitro studies of bystander phenomena, since the proteins of lysed dead cells may participate in driving bystander responses. 相似文献
995.
Ionic Fluids Containing Both Strongly and Weakly Interacting Ions of the Same Charge Have Unique Ionic and Chemical Environments as a Function of Ion Concentration 下载免费PDF全文
Dr. Hui Wang Steven P. Kelley Jimmy W. Brantley III Dr. Gregory Chatel Dr. Julia Shamshina Dr. Jorge F. B. Pereira Varun Debbeti Prof. Allan S. Myerson Prof. Robin D. Rogers 《Chemphyschem》2015,16(5):993-1002
Liquid multi‐ion systems made by combining two or more salts can exhibit charge ordering and interactions not found in the parent salts, leading to new sets of properties. This is investigated herein by examining a liquid comprised of a single cation, 1‐ethyl‐3‐methylimidazolium ([C2mim]+), and two anions with different properties, acetate ([OAc]?) and bis(trifluoromethylsulfonyl)imide ([NTf2]?). NMR and IR spectroscopy indicate that the electrostatic interactions are quite different from those in either [C2mim][OAc] or [C2mim][NTf2]. This is attributed to the ability of [OAc]? to form complexes with the [C2mim]+ ions at greater than 1:1 stoichiometries by drawing [C2mim]+ ions away from the less basic [NTf2]? ions. Solubility studies with molecular solvents (ethyl acetate, water) and pharmaceuticals (ibuprofen, diphenhydramine) show nonlinear trends as a function of ion content, which suggests that solubility can be tuned through changes in the ionic compositions. 相似文献
996.
Molecular Sensing with Hyperpolarized 129Xe Using Switchable Chemical Exchange Relaxation Transfer 下载免费PDF全文
Dr. Nicola J. Rogers James L. Krupa Dr. Galina E. Pavlovskaya Prof. Dr. Neil R. Thomas Dr. Henryk M. Faas Prof. Dr. Thomas Meersmann 《Chemphyschem》2015,16(11):2294-2298
An approach for hyperpolarized 129Xe molecular sensors is explored using paramagnetic relaxation agents that can be deactivated upon chemical or enzymatic reaction with an analyte. Cryptophane encapsulated 129Xe within the vicinity of the paramagnetic center experiences fast relaxation that, through chemical exchange of xenon atoms between cage and solvent pool, causes accelerated hyperpolarized 129Xe signal decay in the dissolved phase. In this proof‐of‐concept work, the relaxivity of Gadolinium III‐DOTA on 129Xe in the solvent was increased eightfold through tethering of the paramagnetic molecule to a cryptophane cage. This potent relaxation agent can be ′turned off′ specifically for 129Xe through chemical reactions that spatially separate the GdIII centre from the attached cryptophane cage. Unlike 129Xe chemical shift based sensors, the new concept does not require high spectral resolution and may lead to a new generation of responsive contrast agents for molecular MRI. 相似文献
997.
Daugirdas Tomas Racys Julian Eastoe Per-Ola Norrby Isabelle Grillo Sarah E. Rogers Guy C. Lloyd-Jones 《Chemical science》2015,6(10):5793-5801
Under optimised conditions, the Trost modular ligand (TML) series induces high levels of asymmetric induction in an extraordinarily wide range of reactions involving palladium π-allyl intermediates. Prior mechanistic investigations into reactions involving Pd-η
3-C6H9 intermediates have focussed on the monomeric 13-membered ring formed via P,P-chelation of the ligand to Pd. However, it is also recognised that ring-opening oligomerisation provides a pool of high nuclearity Pd-η
3-C6H9 species that, by affording a low level, or even the opposite sense, of asymmetric induction relative to the mononuclear species, are responsible for a reduction in selectivity under non-optimised conditions. Herein we describe an investigation by NMR spectroscopy, molecular mechanics, molecular dynamics, and small-angle neutron scattering (SANS), of a Pd-η
3-C6H9 cation bearing the 1,2-diaminocyclohexane TML ligand (2). Using both nondeuterated and perdeuterated (D47) isotopologues of the resulting complexes ([1]+), we show that a two-stage oligomerisation-aggregation process forms self assembled cylindrical aggregates of very high nuclearity (up to 56 Pd centres). We also investigate how concentration, solvent and counter-anion all modulate the extent of oligomerisation. 相似文献
998.
Experimental studies of steady streaming flows are presented for spheroids of various aspect ratios oscillating in a viscous
fluid along their axis of symmetry at Reynolds numbers up to 150 and normalized oscillation amplitudes up to 1.2. The steady
streaming component of the flow is visualized using phase-locked particle pathline images along the central plane of the spheroid.
The extent of the inner region of the flow, characterized by the distance to the stagnation points, appears to depend on a
length scale based on the spheroid aspect ratio and equivalent radius. Spheroids were also oscillated at a nonzero angle with
respect to their axis of symmetry. The angular displacement of the stagnation points on the surface of these obliquely oscillated
spheroids is related to the aspect ratio and the angle of oscillation. 相似文献
999.
This paper presents information on the usefulness of a particular aluminum-particle-filled epoxy for dynamic modeling. Damping
characteristics in terms of the loss factor are presented for this epoxy and some structural metals. Though the damping of
the epoxy was larger than that of any metal tested, it can still be considered small. Portal frames were modeled using the
epoxy. Natural frequencies of vibration for the metal frames and epoxy models were determined. The scaled-epoxy-model frequencies
accurately predicted the metal prototype frequencies. A possible area of error is pointed out with respect to the modeling
of the shear modulus. 相似文献
1000.
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