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51.
Two main existence conditions for solutions of variational relation problems are established without convexity. The first one is based on a finite solvability property and the second one on generalized KKM mappings. These conditions unify and strengthen several existing results in the literature on the topic. A model of satisficing process by rejection is considered which gives an economic interpretation of the introduced concepts. 相似文献
52.
Matrix Heterogeneity Effects on Gas Transport and Adsorption in Coalbed and Shale Gas Reservoirs 总被引:2,自引:0,他引:2
In coalbeds and shales, gas transport and storage are important for accurate prediction of production rates and for the consideration
of subsurface greenhouse gas sequestration. They involve coupled fluid phenomena in porous medium including viscous flow,
diffusive transport, and adsorption. Standard approach to describe gas–matrix interactions is deterministic and neglects the
effects of local spatial heterogeneities in porosity and material content of the matrix. In this study, adopting weak-noise
and mean-field approximations and using a statistical approach in spectral domain, matrix heterogeneity effects are investigated
in the presence of non-equilibrium adsorption with random partition coefficient. It is found that the local heterogeneities
can generate non-trivial transport and kinetic effects which retard gas release from the matrix and influence the ultimate
gas recovery adversely. Macro-transport shows 1/[1 + N
Pe
/(1 + N
Pe
)] dependence on the Péclet number, and persists at the diffusive ultra-low permeability limit. Macro-kinetics is directly
related to Thiele modulus by the following expression: N
Th
/(1 + 2N
Pe
). It leads to trapping of gas in the adsorbed phase during its release from the matrix, and to an adsorption threshold during
the gas uptake by the matrix. Both effects are proportional to the initially available adsorbed gas amount and becomes more
pronounced with the increasing variance of the porosity field. Consequently, a new upscaled deterministic gas mass balance
is proposed for practical purposes. Numerical results are presented showing free and adsorbed gas distributions and fractional
gas sorption curves for unipore coal matrix exhibiting Gaussian porosity distribution. This study is a unique approach for
our further understanding of the coalbeds and gas shales, and it is important for the development of sound numerical gas production
and sequestration models. 相似文献
53.
A. J. Blotcky W. C. Duckworth A. Ebrahim F. K. Hamel E. P. Rack R. B. Sharma 《Journal of Radioanalytical and Nuclear Chemistry》1989,134(1):151-160
Vanadium in serum was investigated by pre-irradiation chemistry neutron activation analysis employing anion exchange chromatography and post-irradiation neutron activation employing solvent extraction techniques. From a comparison of these techniques it is concluded that vanadium is present in human serum in the sub-ppb range. 相似文献
54.
An unexpected three-component condensation reaction between an isocyanide, isoquinoline and a strong CH-acid efficiently provides 1,2-dihydroisoquinoline derivatives in a one-pot reaction in water at 70 °C without using any catalyst. 相似文献
55.
Dadkhah Davood Zomorodi Mariam Hosseini Seyed Ebrahim 《International Journal of Theoretical Physics》2021,60(9):3271-3285
International Journal of Theoretical Physics - In the present work, a novel approach was proposed to optimize the teleportation cost in Distributed Quantum Circuits (DQCs) by applying a new... 相似文献
56.
Andrei K. Whaley Weaam Ebrahim Mona El-Neketi Elena U. Ancheeva Ferhat Can Özkaya Nina I. Pryakhina Nadezhda U. Sipkina Vladimir G. Luzhanin Zhen Liu Peter Proksch 《Tetrahedron letters》2017,58(22):2171-2173
Chemical investigation of the aerial parts of Iris lactea afforded three new flavone C-glycosides including 4?-O-acetyl-embinin (1), 2?,4?-O-diacetyl-embinin (2) and 6″,4?-O-diacetyl-embinin (3) along with the known analogue embinin (4). Their structures were elucidated by 1D and 2D NMR spectroscopic analysis as well as by HRESIMS data. The sugars were characterized following acid hydrolysis of the respective glycosides and TLC analysis compared to known standards. Duplicated signals can be observed in the NMR spectra, indicating the presence of rotamers caused by rotational hindrance around the glycosyl-flavone CC linkage. All isolated compounds were tested for their antimicrobial and cytotoxic activities but found to be inactive. 相似文献
57.
This study aimed at polymerization of methyl methacrylate with novel catalysts in the atom transfer radical polymerization (ATRP) condition at 90 °C. This was accomplished using CuBr/N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (CuBr–AEAPTMS) as a homogeneous catalyst and one time with CuBr@AEAPTMS/SBA-15 as a heterogeneous catalyst. Catalysts were characterized using TGA, FT-IR, and UV–Vis spectroscopy. The structural analysis of the polymer was carried out by 13C NMR spectroscopy and GPC. Three characteristic parts of polymer produced by ATRP method including the initiator, monomer units, and end group was shown in 13C NMR spectra. In addition, the presence of C–Br unit showed that the polymerization process is alive. The 1H NMR analysis was used for kinetic investigation of methyl methacrylate polymerization with homogeneous and heterogeneous catalysts that showed high monomer conversion (98 and 90% after 35 min, respectively) and good control of molecular weight with a dispersity (Ð = 1.5–1.7). In addition, the plot of ln ([monomer]0/[monomer] t ) versus time gave linear relationships indicating a constant concentration of the propagating species throughout the polymerization. Finally, the results of the polymerization using heterogeneous catalyst compared with homogeneous catalyst revealed that it was according to ATRP method. 相似文献
58.
N,N′‐Diiodo‐N,N′‐1,2‐ethandiylbis(p‐toluene sulfonamide) (NIBTS) is a good and new reagent for synthesis of 2‐arylbenzimidazoles and 2‐arylbenzothiazoles at room temperature under solvent‐free condition with good to high yield. Absence of solvent, short reaction times, non‐corrosive, operational simplicity and environmentally friendliness are the main advantages of this procedure. 相似文献
59.