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951.
The motion of two immiscible liquids in a plane channel is analyzed for the case in which the flow conditions and the interactions between the liquids and the solid surface maintain the displaced fluid attached to the wall. The Galerkin Finite Element Method is used to compute the velocity field and the configuration of the interface between the two fluids. We compare the residual mass fraction left on the wall with its two counterparts in capillary tubes, namely residual mass fraction and dimensionless layer thickness of the displaced fluid. The main result of this comparison was that although there is a qualitative similarity concerning the layer thickness between the two cases, the residual fraction of mass presented an important difference, showing that when the aspect ratio of the capillary passage is large there is an increase in the displacement efficiency. The thickness of the displaced liquid film attached to the channel walls is a function of the capillary number (Ca) and the viscosity ratio (Nμ). A map of streamlines in the Cartesian space (Ca, Nμ) with the different flow regimes of the problem is presented. We also showed that we can adapt the available analytical results obtained for gas-displacement in capillary tubes to the plane channel case, for low values of Ca. 相似文献
952.
Long lasting phosphorescence in barium aluminates can be achieved by doping with rare earth ions in divalent charge states. The rare earth ions are initially in a trivalent charge state, but are reduced to a divalent charge state before being doped into the material. In this paper, the reduction of trivalent rare earth ions in the BaAl2O4 lattice is studied by computer simulation, with the energetics of the whole reduction and doping process being modelled by two methods, one based on single ion doping and one which allows dopant concentrations to be taken into account. A range of different reduction schemes are considered and the most energetically favourable schemes identified. 相似文献
953.
Ross AJ Dreiocker F Schäfer M Oomens J Meijer AJ Pickup BT Jackson RF 《The Journal of organic chemistry》2011,76(6):1727-1734
The structure of the alkylzinc-tetramethylethyl-enediamine (TMEDA) cluster cation 3 has been determined in the gas phase by a combination of tandem mass spectrometry, infrared multiphoton dissociation (IRMPD) spectroscopy, and DFT calculations. Both sets of experimental results establish the existence of a strongly stabilizing interaction of TMEDA with the zinc cation. High-level DFT calculations on the alkylzinc-TMEDA cluster cation 3 allowed the identification of two low energy conformers, each featuring a four-coordinate zinc atom with a bidentate TMEDA ligand, and internal coordination from the carbonyl group of the Boc group to zinc. The experimental IRMPD spectrum is reproduced with an appropriately weighted combination of the IR spectra of the two conformers identified by theory. DFT calculations on the structure of the alkylzinc halide 2 with coordinated TMEDA using the PCM model of water solvent suggest that TMEDA can promote ionization of the zinc-iodine bond in organozinc iodides under aqueous conditions, providing a credible explanation for the role of TMEDA in stabilizing the carbon-zinc bond. Reaction of the serine-derived iodide 1 with aryl iodides "on water", promoted by nano zinc in the presence of PdCl(2)(Amphos)(2) (5 mol %) and TMEDA, leads to the formation of protected phenylalanine derivatives 4 in reasonable yields. In the case of ortho-substituted aryl iodides and aryl iodides that are solids at room temperature, conducting the reaction at 65 °C gives improved results. In all cases, the product 5 of reductive dimerization of the iodide 1 is also isolated. 相似文献
954.
Arnold R Augier C Baker J Barabash AS Basharina-Freshville A Blondel S Bongrand M Broudin-Bay G Brudanin V Caffrey AJ Chapon A Chauveau E Durand D Egorov V Flack R Garrido X Grozier J Guillon B Hubert P Hugon C Jackson CM Jullian S Kauer M Klimenko A Kochetov O Konovalov SI Kovalenko V Lalanne D Lamhamdi T Lang K Liptak Z Lutter G Mamedov F Marquet Ch Martin-Albo J Mauger F Mott J Nachab A Nemchenok I Nguyen CH Nova F Novella P Ohsumi H Pahlka RB Perrot F Piquemal F Reyss JL Richards B Ricol JS 《Physical review letters》2011,107(6):062504
We report results from the NEMO-3 experiment based on an exposure of 1275 days with 661 g of (130)Te in the form of enriched and natural tellurium foils. The ββ decay rate of (130)Te is found to be greater than zero with a significance of 7.7 standard deviations and the half-life is measured to be T(?)(2ν) = [7.0 ± 0.9(stat) ± 1.1(syst)] × 10(20) yr. This represents the most precise measurement of this half-life yet published and the first real-time observation of this decay. 相似文献
955.
We introduce noncooperatively optimized tolerance (NOT), a game theoretic generalization of highly optimized tolerance (HOT), which we illustrate in the forest fire framework. As the number of players increases, NOT retains features of HOT, such as robustness and self-dissimilar landscapes, but also develops features of self-organized criticality. The system retains considerable robustness even as it becomes fractured, due in part to emergent cooperation between players, and at the same time exhibits increasing resilience against changes in the environment, giving rise to intermediate regimes where the system is robust to a particular distribution of adverse events, yet not very fragile to changes. 相似文献
956.
Ramazanoglu M Laver M Ratcliff W Watson SM Chen WC Jackson A Kothapalli K Lee S Cheong SW Kiryukhin V 《Physical review letters》2011,107(20):207206
Polarized small-angle neutron scattering studies of single-crystalline multiferroic BiFeO(3) reveal a long-wavelength spin density wave generated by ~1° spin canting of the spins out of the rotation plane of the antiferromagnetic cycloidal order. This signifies weak ferromagnetism within mesoscopic regions of dimension 0.03 microns along [110], to several microns along [111], confirming a long-standing theoretical prediction. The average local magnetization is 0.06 μ(B)/Fe. Our results provide an indication of the intrinsic macroscopic magnetization to be expected in ferroelectric BiFeO(3) thin films under strain, where the magnetic cycloid is suppressed. 相似文献
957.
A diode-pumped actively mode-locked Tm3?-doped double-clad silica fiber laser providing up to 11.8 W of average output power and pulse widths in mode-locked operation of 38 ps at a repetition rate of 37.88 MHz is reported. Pulse energies of up to 314 nJ were obtained. 相似文献
958.
High-power diode-pumped fiber laser operating at 3 μm 总被引:1,自引:0,他引:1
A high-power diode-cladding-pumped Ho3?-doped fluoride glass fiber laser operating in cascade mode is demonstrated. The ?I?→?I? and ?I?→?I? laser transitions produced 0.77 W at a measured slope efficiency of 12.4% and 0.24 W at a measured slope efficiency of 5.2%, respectively. Using a long fiber length, which forced a large threshold for the ?I?→?I? transition, a wavelength of 3.002 μm was measured at maximum output power, making this system the first watt-level fiber laser operating in the mid-IR. 相似文献
959.
The dissociation behavior of phosphorylated and sulfonated peptide anions was explored using metastable atom-activated dissociation
mass spectrometry (MAD-MS) and collision-induced dissociation (CID). A beam of high kinetic energy helium (He) metastable
atoms was exposed to isolated phosphorylated and sulfonated peptides in the 3– and 2– charge states. Unlike CID, where phosphate
losses are dominant, the major dissociation channels observed using MAD were Cα – C peptide backbone cleavages and neutral losses of CO2, H2O, and [CO2 + H2O] from the charge reduced (oxidized) product ion, consistent with an electron detachment dissociation (EDD) mechanism such
as Penning ionization. Regardless of charge state or modification, MAD provides ample backbone cleavages with little modification
loss, which allows for unambiguous PTM site determination. The relative abundance of certain fragment ions in MAD is also
demonstrated to be somewhat sensitive to the number and location of deprotonation sites, with backbone cleavage somewhat favored
adjacent to deprotonated sites like aspartic acid residues. MAD provides a complementary dissociation technique to CID, ECD,
ETD, and EDD for peptide sequencing and modification identification. MAD offers the unique ability to analyze highly acidic
peptides that contain few to no basic amino acids in either negative or positive ion mode. 相似文献
960.
Let A be a *-algebra. An additive mapping E : A → A is called a Jordan *-derivation if E(X2) = E(x)x*+xE(x) holds, for all x 6 A. These mappings have been extensively studied in the last 6 years by Bresar, Semrl, Vukman and Zalar because they are closely connected with the problem of representability of quadratic functionals by sesquilinear forms. This study was, however, always in the setting of associative rings. In the present paper we study Jordan *-derivations on the Cayley-Dickson algebra of octonions, which is not associative. Our first main result is that every Jordan *-derivation on the octonion algebra is of the form E(x)=ax*-xa. In the terminology of earlier papers this means that every Jordan *-derivation on the octonion algebra is inner. This generalizes the known fact that Jordan *-derivations on complex and quaternion algebras are inner. Our second main result is a representation theorem for quadratic functionals on octonion modules. Its proof uses the result mentioned above on Jordan *-derivations. 相似文献