High-order accurate dissipative weighted compact nonlinear schemes

Based on the method deriving dissipative compact linear schemes (DCS), novel high-order dissipative weighted compact nonlinear schemes (DWCNS) are developed. By Fourier analysis,the dissipative and dispersive features of DWCNS are discussed. In view of the modified wave number, the DWCNS are equivalent to the fifth-order upwind biased explicit schemes in smooth regions and the interpolations at cell-edges dominate the accuracy of DWCNS. Boundary and near boundary schemes are developed and the asymptotic stabilities of DWCNS on both uniform and stretching grids are analyzed. The multi-dimensional implementations for Euler and Navier-Stokes equations are discussed. Several numerical inviscid and viscous results are given which show the good performances of the DWCNS for discontinuities capturing, high accuracy for boundary layer resolutions, good convergent rates (the root-mean-square of residuals approaching machine zero for solutions with strong shocks) and especially the damping effect on the spudous oscillations which were found in the solutions obtained by TVD and ENO schemes.     

Some evaluation of q-analogues of Euler sums

In this paper, we discuss the analytic representations of q-Euler sums which involve q-harmonic numbers through q-polylogarithms, either linearly or nonlinearly, and give explicit formulae for several classes of q-Euler sums in terms of q-polylogarithms and q-special functions. Furthermore, we develop new closed form representations of sums of quadratic and cubic parametric q-Euler sums. Finally, we can find that the q-Euler sums are reducible to the classical Euler sums when q approaches 1.     

纳米TiO-2对模型病毒-f2噬菌体的吸附特性

为了提高饮用水处理系统对病毒的去除效果,本研究采用静态实验,研究纳米TiO2对模型病毒—f2噬菌体的吸附去除特性,系统考察TiO2投加浓度、病毒浓度、温度及pH值等因素对吸附效果的影响.实验结果表明：f2噬菌体在纳米TiO2表面的吸附符合准二级吸附动力学模型,遵循化学吸附机理,颗粒内扩散为该吸附过程中的速率控制步骤,但不是唯一控制步骤;纳米TiO2对f2噬菌体的吸附符合Freundlich等温吸附模型（qe=27.4Ce1.24）,属于多层吸附类型;在20~40℃范围内,温度对纳米TiO2的吸附性能影响不大,而酸性条件下更有利于纳米TiO2对f2噬菌体的吸附.     

Fluorometric determination and imaging of glutathione based on a thiol-triggered inner filter effect on the fluorescence of carbon dots

The authors describe a sensitive method for determination of glutathione (GSH) that is based on a thiol-triggered inner filter effect on the fluorescence of N-doped carbon dots (N-doped CDs). N-doped CDs with a quantum yield as high as 31% were prepared by a one-pot procedure, and 5,5′-dithiobis-(2-nitrobenzoic acid) was employed as a reagent for GSH recognition. The reaction product (5-thio-2-nitrobenzoic acid; TNB) acts as an absorber of the 410-nm light used to photo-excite the N-doped CDs. Hence, the fluorescence of N-doped CDs (peaking at 510 nm) is reduced with increasing concentrations of GSH. As little as 30 nM of GSH can be detected by this method. The approach was successfully applied to (a) food analysis, (b) an investigation of an oxidative stress model, and (c) to live cells imaging. The method does not require the surface of N-doped CDs to be chemically modified, and a linkage between receptor and fluorophore is not needed. In our perception, the method may become a viable tool for the detection and imaging of thiols.

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Graphical abstract Fluorescence sensing strategy for glutathione detection based on a thiol-triggered inner filter effect via new N-doped carbon dots and application to food analysis, oxidative stress study and cell imaging.

     

Synthesis and relaxivity of Gd(III), Fe(III) and Mn(II) complexes with dihydropyridine derivative of diethylenetriaminepentaacetic acid

A novel ligand of DTPA-dihydropyridine derivative was synthesized by reaction of DTPA-dianhydride with 4-aniline-1,4-dihydropyridine. Its complexes of gadolinium, manganese and iron were prepared. Their spin-lattice relaxivities (T₁) were investigated. The results show that the NMR T₁ relaxivitives (R₁) for complexes of Fe(III), Mn(II) are less than that of Gd(III) complex, which has a high relaxivity (R₁) on the surrounding water protons, indicating that the Gd(III) complex possesses the precondition to be contrast agents for magnetic resonance imaging.     

Microstructure evolution and properties of Al/Al–Mg–Si alloy clad wire during heat treatment

In this paper, heat treatment was carried out on Al/Al–Mg–Si alloy clad wire, and microstructure evolution and properties of Al/Al–Mg–Si alloy clad wire during heat treatment were investigated. During solution, contents of Mg and Si in inner matrix increased due to dissolution of primary Mg₂Si, and they also increased in outer matrix because Mg and Si diffused across the interface. Tensile strength of the clad wire increased firstly and then decreased, and elongation continuously increased, while conductivity continuously decreased with the increase in solution time. In aging process, Mg₂Si precipitated in both inner core and outer layer, and the content and average diameter of the precipitate increased with the increase in aging time. The content of precipitate was higher, and the average diameter was bigger in inner core. Tensile strength of the clad wire increased firstly and then decreased with the increase in aging time, and the elongation continuously decreased, while the conductivity continuously increased. The peak tensile strength of 202 MPa occurred at 8 h, when the corresponding elongation was 20 % and the conductivity reached 56.07 %IACS. Even tensile strength of the prepared clad wire approximately equaled to that of Al–0.5Mg–0.35Si alloy 203 MPa, the conductivity was obviously improved from 54.2 to 56.07 %IACS.     

Study on preparation and properties of molybdenum alloys reinforced by nano-sized ZrO<Subscript>2</Subscript> particles

The nano-sized ZrO₂-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO₂ particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO₂ particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO₂ particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %.     

铋和镍对钒磷氧化物催化剂性能的影响YunHinTaufiq-Yap,ChoonSeonYuen,Nawi简

Vanadium phosphorus oxide (VPO) catalysts were synthesized by the dihydrate method which involved the two steps for the preparation of the dihydrate (VOPO₄×2H₂O) and the precursor hemihydrate (VOHPO₄×0.5H₂O). Bi and Ni salt were added into the mixture of VOPO₄×2H₂O and isobutanol, and the obtained precursors were calcined in a flow of a n-butane/air mixture to produce the promoted VPO catalysts. The catalysts were characterized by X-ray diffraction (XRD), N₂ adsorption-desorption, inductively coupled plasma-atomic emission spectroscopy, scanning electron microscopy (SEM), and H₂ temperature-programmed reduction (H₂-TPR). Their catalytic properties were tested using a fixed-bed microreactor. All the catalysts gave main XRD peaks at 2θ = 22.9°, 28.5°, and 30.0°, attributing to the (020), (204), and (221) planes of the pyrophosphate phase (VO)₂P₂O₇, respectively. The promoted catalysts have smaller crystallite size and higher specific surface areas. SEM micrographs revealed the formation of more prominent plate-like crystallites that were arranged as rosette clusters. H₂-TPR results showed that the promoted catalysts had lower reduction peak temperatures and possessed higher amounts of V⁵⁺-O^2- and V⁴⁺-O^- pairs, which gave higher selectivity and activity in the selective oxidation of n-butane to maleic anhydride.     

ESR Study on Scavenging Effect of Squalene on Free Radicals in Mainstream Cigarette Smoke

Radicals in mainstream cigarette smoke (MCS) have been proposed to contribute to the harm caused by cigarette smoking. In the present study, we used natural antioxidant, squalene, to treat cigarette filters and tobacco for scavenging gas- and particulate-phase free radicals in MCS. The scavenging activities of cigarette filter and tobacco containing squalene against gas and particulate-phase free radicals were detected and quantified using spin-trapping or directly electron spin resonance spectroscopy method. The results revealed that squalene could significantly scavenge gas- and particulate-phase free radicals in MCS in a dose-dependent manner. The radical-scavenging activity of cigarette filter treatment was higher than that of tobacco treatment, irrespective of either gas-phase free radicals, or particulate-phase free radicals in MCS. Among them, 3 mg squalene/filter treatment showed that the highest scavenging effects against gas- and particulate-phase free radicals were 35.9 and 35.4%, respectively. The use of squalene as potential scavenger for reducing free radicals in cigarette smoke is discussed.     

Spiral waves in CIMA model and its LBGK simulation

Introduction In 1952, Turing set up a formalism capable of describing formation of stationary concentration patterns by symmetry breaking in'reaction-diffusion systemsl']. This type of spatiallydistributed stationary concentration pattern is called Turing pattern. Another type of interesting structure is concentration spiral wave which is also involved in reaction-diffusion systems.In a special case, called the activator-inhibitor system, the following chemicajs are involved:an activator capa…