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221.
222.
For axisymmetric dispersion in laminar flow in a cylinder of circular cross section, we report the full time dependence of the first three dispersion coefficients, viz. X
0, X
1 and X
2. We investigate the use of a variety of transverse averages. We also indicate the dependence of the dispersion coefficients on the initial solute distribution and on the chemical activity of the solute. 相似文献
223.
M. S. Malghani R. M. Lees J. W. C. Johns 《International Journal of Infrared and Millimeter Waves》1987,8(8):803-825
The far-infrared (FIR) spectrum of CH3NH2 has been studied in the 25–125 cm–1 region at a resolution of 0.005 cm–1 with a BOMEM Fourier transform spectrometer. All of therR branches with K rotational quantum number from 5 to 13 have been identified for A-a and E-a torsion-inversion symmetries in the ground torsional state, as well as some branches of A-s and E-s symmetries and some in excited torsional states. The observed branches have been fitted to series expansions in order to determine the branch origins. 相似文献
224.
W F Johns 《The Journal of organic chemistry》1965,30(11):3993-3994
225.
Ohne Zusammenfassung 相似文献
226.
227.
Y. Kabbadj M. Herman G. Di Lonardo L. Fusina J. W. C. Johns 《Journal of Molecular Spectroscopy》1991,150(2)
Absorption spectra of C2H2 have been recorded between 50 and 1450 cm−1, with a resolution always better than 0.005 cm−1, using two different Fourier transform spectrometers. Analysis of the data provided two sets of results. First, the bending levels with Σt Vt(t = 4, 5) ≤ 2 were characterized by a coherent set of 34 parameters derived from the simultaneous analysis of 15 bands, performed using a matrix Hamiltonian. The following main parameters were obtained (in cm−1): ω40 = 608.985196(14), ω50 = 729.157564(10); B0 = 1.17664632(18), α4 = −1.353535(86) × 10−3, α5 = −2.232075(40) × 10−3; q40 = 5.24858(12) × 10−3, and q50 = 4.66044(12) × 10−3, with the errors (1σ) on the last quoted digit. Second, a more complete set of bending levels with Σt Vt ≤ 4, some of which have never previously been reported, and also including V2 = 1 have been fitted to 80 parameters. This simultaneous fit involved 43 bands and used the same full Hamiltonian matrix. Some perturbations which affect the higher excited levels are discussed. 相似文献
228.
Sheppard S Mantle MD Sederman AJ Johns ML Gladden LF 《Magnetic resonance imaging》2003,21(3-4):365-367
Magnetic resonance imaging is used to follow the removal process of a visco-elastic surfactant (VES) fracturing fluid in Bentheimer sandstone cores at typical reservoir temperatures (T=333 K). Two displacing fluids were investigated, a Gadolinium doped water phase (1M NaCl solution), and a Gadolinium doped hydrocarbon phase (Mineral Spirits). In addition to flow characteristics obtained by conventional core-flooding, i.e., the macroscopically averaged volumetric flow rates and differential pressures, we have also measured the saturation profiles and characteristic displacement patterns during all stages of the removal process. To acquire these data we have used quantitative one-dimensional chemically specific profiling along with fast two-dimensional imaging experiments while flooding Bentheimer sandstone cores in situ in the spectrometer. Our results show that both displacement processes (complex fluid displaced by water or hydrocarbon phase) are dominated by the large viscosity contrasts present. However, distinct differences were found between the displacement characteristics of water and hydrocarbon, which confirmed the sensitivity of the complex fracturing fluid to the displacing fluid. 相似文献
229.
Isoelectric buffers are attractive for electrophoresis because of their low conductivity, and their compatibility with indirect photometric detection in capillary electrophoresis (CE) where they do not interfere with the detection by exhibiting competitive displacement of the UV-absorbing probe ion. N-carboxymethylated polyethyleneimine (CMPEI) was prepared by introducing a half molar equivalent of carboxylate groups onto a polyethyleneimine backbone. Its isoelectric point determined by conductometric titration and from the pH of its dilute aqueous solution is approx. 6.8, which allows isoelectric buffering at a lower pH compared to histidine (pI7.7). Although the isoelectric point is somewhat diffuse, as expected for a polymeric compound, it exhibits a buffering capacity at a pI point of about twice that of histidine. Studies of electroosmotic flow (EOF) profile at various pH values in fused silica capillaries showed that CMPEI adsorbs onto the fused silica wall and reverses the EOF at pH < 6.5. CMPEI was applied as a buffer in an electrolyte containing 0.5 mM of the anionic dye tartrazine used as the probe for indirect detection of anions. The separation system exhibited a stable baseline, no system peaks, separation efficiencies of up to 195,000 theoretical plates, and detection limits down to 0.2 microM or 2 amol of injected analyte. 相似文献
230.