Bounded Domain Problem for the Modified Buckley–Leverett Equation

The focus of the present study is the modified Buckley–Leverett (MBL) equation describing two-phase flow in porous media. The MBL equation differs from the classical Buckley–Leverett (BL) equation by including a balanced diffusive–dispersive combination. The dispersive term is a third order mixed derivatives term, which models the dynamic effects in the pressure difference between the two phases. The classical BL equation gives a monotone water saturation profile for any Riemann problem; on the contrast, when the dispersive parameter is large enough, the MBL equation delivers a non-monotone water saturation profile for certain Riemann problems as suggested by the experimental observations. In this paper, we first show that for the MBL equation, the solution of the finite interval \([0,L]\) boundary value problem converges to that of the half line \([0,+\infty )\) boundary value problem exponentially as \(L\rightarrow +\infty \) . This result provides a justification for the use of the finite interval in numerical studies for the half line problem [Y. Wang and C.-Y. Kao, Central schemes for the modified Buckley–Leverett equation, J. Comput. Sci. 4(1–2), 12 – 23, 2013]. Furthermore, we numerically verify that the convergence rate is consistent with the theoretical derivation. Numerical results confirm the existence of non-monotone water saturation profiles consisting of constant states separated by shocks.     

Workshop on in‐situ studies of materials processing

More than eighty scientists from over ten different countries in Europe and America descended on Diamond Light Source in Oxfordshire to participate in the International Workshop on X-ray Spectroscopy of Magnetic Solids on June 10–21, 2010. The XRMS meetings have demonstrated to be a fruitful forum for informal discussion of recent results and future projects of synchrotron-radiation-based research on magnetism and also serve for the formation of new collaborations. The meetings are organized in sessions dedicated to specific scientific topics and experimental techniques. The absence of parallel sessions allows all the participants to take part in the discussion and to have a comprehensive view of the latest achievements and of the envisioned developments in the field. The previous meeting in the series was held last year at the synchrotron Soleil in St Aubin near Paris. The emerging new opportunities for magnetic spectroscopy, such as offered by the beamline for advanced dichroism experiments (BLADE), with its three intertwined assets of polarization, coherence, and time resolution, made it timely for the international community to convene at Diamond.     

Effect of Cu/In ratio on properties of CuInSe2 thin films prepared by selenization of Cu‐In layers

In this paper, the chalcopyrite CuInSe2 thin films were fabricated from a selenization of electrodeposited Cu‐In layers. In this study, the electrodeposition time of the In layer was set, but that for the Cu layer was not. The thin films were selenized in a sealed glass tube with pure Se powder by three different Cu layer samples at various electrodeposition times at 500 °C for 2 hours. An FE‐SEM image of the sample shows that the copper‐rich product has irregular agglomerates with a dense surface. The X‐ray diffraction patterns show CuInSe₂ peaks for all samples. However, the X‐ray diffraction pattern reveals CuSe₂ peaks when the electrodeposition time of the Cu layer increases. On the other hand, the band gap (E_g) of the samples decreases from 1.15 to 1.07 eV when the Cu/In ratio increases.     

K5(UO2)2[Si4O12(OH)]: a uranyl silicate containing chains of four silicate tetrahedra linked by SiO...HOSi hydrogen bonds

A new uranium(VI) silicate, K5(UO2)2[Si4O12(OH)], has been synthesized by a high-temperature, high-pressure hydrothermal method. It crystallizes in the orthorhombic space group Pbcm (No. 57) with a = 13.1274(7) A, b = 12.2635(7) A, c = 22.233(1) A, and Z= 8. Its structure consists of unbranched chains of four silicate tetrahedra extending along the b axis linked together via corner-sharing by UO6 tetragonal bipyramids to form a 3-D framework, which delimits intersecting channels along the c and b axes to accommodate K+ cations. A hydrogen atom is bonded to a terminal oxygen of a terminal silicate in the oligosilicate anion. Adjacent chains are linked along the b axis by hydrogen bonds. The sample shows a resonance at 14.7 ppm the 1H MAS NMR spectrum, which is assigned to the SiO...HOSi hydrogen bond. A comparison of uranyl silicate structures is made.     

交流示波极谱滴定的研究(Ⅻ)——中和滴定

本文系统地报导了交流示波极谱滴定在中和滴定中的应用,解决了弱酸弱碱在水溶液中直接滴定等问题。同时提出了中和滴定的两大类指示剂的概念,并且总结了它们的性质。因此,示波极谱中和滴定将大大地丰富中和滴定的内容,扩大其应用范围。     

Depth profiling of inks in authentic and counterfeit banknotes by electrospray laser desorption ionization/mass spectrometry

Electrospray laser desorption ionization is an ambient ionization technique that generates neutrals via laser desorption and ionizes those neutrals in an electrospray plume and was utilized to characterize inks in different layers of copy paper and banknotes of various currencies. Depth profiling of inks was performed on overlapping color bands on copy paper by repeatedly scanning the line with a pulsed laser beam operated at a fixed energy. The molecules in the ink on a banknote were desorbed by irradiating the banknote surface with a laser beam operated at different energies, with results indicating that different ions were detected at different depths. The analysis of authentic $US100, $100 RMB and $1000 NTD banknotes indicated that ions detected in ‘color‐shifting’ and ‘typography’ regions were significantly different. Additionally, the abundances of some ions dramatically changed with the depth of the aforementioned regions. This approach was used to distinguish authentic $1000 NTD banknotes from counterfeits. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and characterization of bismaleimide–polyurethane crosslinked copolymers

A series of novel crosslinked copolymers of bismaleimide (BMI) and polyurethanes (PU) were prepared by direct copolymerization of BMI monomer and urethane-modified bismaleimide (UBMI). The copolymers were characterized by FT-IR and solid state ¹³C-NMR. The reaction rate of the BMI monomer can be significantly increased by copolymerization with UBMI. The crosslinked copolymers show good mechanical properties and high thermal stability. Studies on glass transition temperatures and dynamic mechanical properties indicate that the copolymer is a homogeneous system as the polyester-type PU employed. The transmission electron microscopy (TEM) of the copolymer illustrated a one-phase structure of the cured resins when the polyester-type PU was incorporated. © 1995 John Wiley & Sons, Inc.     

Conformational analysis of allylamine. An ab initio molecular orbital study

The conformational characteristics of allylamine were investigated by the ab initio STO -3G basis set. The results indicate that the molecule exists in a number of stable conformations through rotations about the CC? NH and CC? CN bonds. The TE (trans-CCNLP , LP representing lone-pair electrons, and eclipsed-CCCH) is the most stable, while TC (trans-CCNLP and cis-CCCN), GE (gauche-CCNLP and eclipsed-CCCH), G′C(gauche′-CCNLP and cis-CCCN), and G′E (gauche′-CCNLP and eclipsed-CCCH) conformations are less stable, respectively, by 0.41, 0.67, 0.92, and 1.14 kcal mol^?1. These results are in general consistent with previous experimental results. Rationale for the conformational characteristics and order of stabilities are explored.