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91.
In oil recovery from fractured reservoirs, dynamic spontaneous imbibition (DSI) plays an important role. Conventional equations
used for characterizing dynamic spontaneous imbibition neglect the effects of the driving forces acting across the wetting
and non-wetting phases which are flowing in opposite directions. Such effects, defined as interfacial coupling effects (ICE),
are known to cause a decrease in the calculated flow rate in drainage processes. Moreover, none of the numerical models have
considered a variable inlet saturation (S*) for DSI. A new theoretical model has been developed using generalized transport equations to describe dynamic spontaneous
imbibition for immiscible two-phase flow processes. The inclusion of interfacial coupling effects provides a more accurate
way to describe dynamic spontaneous imbibition. Furthermore, the addition of variable inlet saturation allows one to establish
whether the inlet-face saturation (S*) increases from the initial saturation to 1−Sro, or whether it can remain constant and equal to one minus the residual saturation
to the non-wetting phase (1−Sro). 相似文献
92.
Ramon Subiros-Funosas Gerardo A. Acosta Ayman El-Faham Fernando Albericio 《Tetrahedron letters》2009,50(45):6200-1844
Here we demonstrate the compatibility of Oxyma-based uronium-type coupling reagent COMU with microwave-assisted peptide synthesizers. Consistent with previous reports, COMU displayed higher efficiency than benzotriazole classical immonium salts HATU and HBTU in the demanding synthesis of the Aib derivative of Leu-Enkephalin pentapeptide and did not yield Oxyma-based byproducts. Thus, the combination of microwave irradiation and COMU resulted in a similar performance in considerably shorter time to that achieved by manual synthesis. 相似文献
93.
Ohne Zusammenfassung 相似文献
94.
In the present work, a rapid method with little sample handling has been developed for determination of 23 selected volatile organic compounds in environmental and wastewater samples. The method is based on headspace solid-phase microextraction (SPME) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) determination using triple quadrupole analyzer (QqQ) in electron ionization mode. The best conditions for extraction were optimised with a factorial design taking into account the interaction between different parameters and not only individual effects of variables. In the optimized procedure, 4 mL of water sample were extracted using a 10 mL vial and adding 0.4 g NaCl (final NaCl content of 10%). An SPME extraction with carboxen/polydimethylsiloxane 75 μm fiber for 30 min at 50°C (with 5 min of previous equilibration time) with magnetic stirring was applied. Chromatographic determination was carried out by GC-MS/MS working in Selected Reaction Monitoring (SRM) mode. For most analytes, two MS/MS transitions were acquired, although for a few compounds it was difficult to obtain characteristic abundant fragments. In those cases, a pseudo selected reaction monitoring (pseudo-SRM) with three ions was used instead. The intensity ratio between quantitation (Q) and confirmation (q) signals was used as a confirmatory parameter. The method was validated by means of recovery experiments (n=6) spiking mineral water samples at three concentration levels (0.1, 5 and 50 μg L(-1)). Recoveries between 70% and 120% were generally obtained with relative standard deviations (RSDs) lower than 20%. The developed method was applied to surface water and wastewater from a wastewater treatment plant and from a municipal solid-waste treatment plant. Several compounds, like chloroform, benzene, trichloroethylene, toluene, tetrachloroethylene, dibromochloromethane, xylenes and bromoform were detected and confirmed in all the samples analyzed. 相似文献
95.
We introduce the concept of Toeplitz-Kre?n-Cotlar triplet on ordered groups and we prove a general dilation result and a general representation result for the positive definite case.This general result includes and extends previous generalizations of the Kre?n extension theorem, the Sz.-Nagy and Foias commutant lifting theorem and the generalized Herglotz-Bochner-Weil theorem. 相似文献
96.
Carole Fraschini Rodica Plesu Jose‐Ramon Sarasua Robert E. Prud'homme 《Journal of Polymer Science.Polymer Physics》2005,43(22):3308-3315
A polylactide of high optical purity was crystallized between 100 and 140 °C, in‐between two glass slides, and its morphology was investigated by polarizing optical microscopy, scanning electron microscopy, and atomic force microscopy, during subsequent heating and cooling cycles between ?15 °C and the crystallization temperature. It was found that dark circular rings show up on cooling on top of the spherulites and represent cracks of about 300 nm in width. This phenomenon is completely reversible, and the heating–cooling curves are centered at about 56 °C, which coincide with the Tg of polylactide. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3308–3315, 2005 相似文献
97.
Jean Devillers Martine Cornus Jean Roussel Jacques Navech Ramon Burgada 《Magnetic resonance in chemistry : MRC》1974,6(4):205-210
The influence of various factors (temperature, nature and concentration of solvent) or the utilisation of various physical methods (tickling or INDOR experiments, for example) are employed to analyse the PMR spectra of some 5-monosubstituted or 4,5-disubstituted 1,3,2-oxazaphospholane derivatives. 相似文献
98.
99.
Marie-Martine Audibert Ramon Vilaseca Jacques Lukasik Jacques Ducuing 《Chemical physics letters》1975,31(2):232-236
The vibrational relaxation of ortho-para-H2 mixtures was studied in the interval 400-50 K. At and above 300 K the ortho and para self-relaxation rates, koo and kpp, are identical within experimental error. In the low temperature range, koo >kpp and koo is found to vary slowly with temperature. 相似文献
100.