Coumarin Based Highly Selective “off-on-off” Type Novel Fluorescent Sensor for Cu<Superscript>2+</Superscript> and S<Superscript>2−</Superscript> in Aqueous Solution

Solvent free synthesis of 6,7-dihydroxy-3-(3-chlorophenyl) coumarin (CFHC) was designed and obtained by the interaction of 2-(2,4,5-trimethoxyphenyl)-1-(3-chlorophenyl)acrylonitrile with pyridinium hydrochloride in the presence of silica gel by using microwave irradiation. The characterization of CFHC was confirmed by FT-IR, ¹H, ¹³C, ¹³C–APT and 2D HETCOR spectroscopy methods. The optical behavior of CFHC towards metal ions was investigated by UV-visible and fluorescence spectroscopy. CFHC showed “on–off” type fluorescence response towards Cu²⁺ with high selectivity in aqueous solution (CH₃CN/H₂O, 9/1, v/v). Once binding with Cu²⁺, CFHC-Cu²⁺ complex also displayed high selectivity for sulfide, resulting in “off–on” type sensing of sulfide anion.

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Graphical abstract Visual fluorescence changes upon addition of various metal ions (5.0 eq.) to CFHC in CH₃CN/H₂O (90:10, v/v) under UV excitation (365 nm)

     

石墨、菱铁矿与超临界水反应的实验研究

 为研究地球深部无机成烃的机制，在金刚石压腔（DAC，温度为800~1 500 ℃，压力略大于1 GPa）中进行了石墨和菱铁矿分别与超临界水反应的实验研究。用气相色谱法分析了气体产物的组成，发现其中均有大量的甲烷生成，并伴有CO₂和CO；此外还有少量其它烃类。上述结果意味着在地球深部高温高压条件下，含碳物质与超临界水反应可能是一种新的、重要的成烃机制。     

Numerical solutions of liquid metal flows by incompressible magneto‐hydrodynamics with heat transfer

A two‐dimensional incompressible magneto‐hydrodynamic code is presented in order to solve the steady state or transient magnetized or neutral convection problems with the effect of heat transfer. The code utilizes a numerical matrix distribution scheme that runs on structured or unstructured triangular meshes and employs a dual time‐stepping technique with multi‐stage Runge–Kutta algorithm. The code can be used to simulate the natural convection with internal heat generation and absorption and nonlinear time‐dependent evolution of heated and magnetized liquid metals exposed to external fields. Copyright © 2008 John Wiley & Sons, Ltd.     

An integrated optical spatial filter

The demonstration of a static integrated optical spatial digital filter based upon the Bragg effect is reported and a design for a programmable filter is suggested.     

Particle tracking in living cells: a review of the mean square displacement method and beyond

The focus of many particle tracking experiments in the last decade has been active systems, such as living cells. In active systems, the particles undergo simultaneous active and thermally driven transport. In contrast to thermally driven transport, particle motion driven by active processes cannot directly be correlated to the rheology of the probed region. The rheology in particle tracking experiments is typically obtained through the mean square displacements (MSD) of the trajectories. Hence, the MSD and its functional form remain the only basic tools to evaluate and compare living cells or other active systems. However, the mechano-structural characteristics of the intracellular environment and the mechanisms driving particle transport cannot be revealed by the MSD alone. Hence, approaches for advanced analysis of particle trajectories have been introduced recently. Here, we present a broad review of the extensive intracellular particle tracking experiments that have been carried out on a wide variety of cell types. Those works utilize the MSD, revealing similarities and differences relating to cell type and experimental setup. We also highlight several advanced trajectory-and displacement-based analysis methods and illustrate their capabilities using particle tracking data obtained from two cancer cell lines. We show that combining these analysis methods with the MSD can reveal additional information on intracellular structure and the existence and nature of active processes driving particle motion in cells.     

Microwave-assisted synthesis of zinc oxide and its performance in photodegradation of CTMAB

Research on Chemical Intermediates - Zinc oxide (ZnO) photocatalyst was prepared by a microwave-assisted method starting from zinc acetate and oxalate. The as prepared photocatalyst was...     

Nonlinear dynamic modeling for fault ride-through capability of DFIG-based wind farm

Fault ride-through (FRT) is a control model enhanced to protect doubly fed induction generator (DFIG) during voltage dip occurring in grid. In this study, stator and rotor circuit dynamic modeling enhanced in terms of simulation performance and fast system responses during instability in DFIG-based wind farm, besides, a FRT capability strategy were enhanced for nonlinear supercapacitor modeling in DFIG-based wind farm. The transient stability analyses of the DFIG with and without supercapacitor as well as positive–negative-sequence dynamic modeling (PNSDM) were compared for three phases, two phases, two-phase-ground and a-phase-ground faults. Furthermore, variations such as DFIG output voltage, DFIG angular speed, DFIG electrical torque and DFIG d–q axis stator current variations were also evaluated. It was found that the DFIG-based wind farm became stable within a short time using the PNSDM and supercapacitor.

     

Experiences with two detached eddy simulation approaches through use of a high-order finite volume solver

In the present study, two advanced detached eddy simulation (DES) approaches, shear-layer-adapted delayed DES and zonal DES in mode II, which are known to help transition from RANS to LES mode, are employed in various flow problems in conjunction with a high-order finite volume solver. The numerical scheme, being only applicable on structured grids, has low-dissipation and low-dispersion features. Such features benefit mostly in the LES mode, minimizing the interference of numerical diffusion with subgrid eddy viscosity. First, corresponding subgrid models are validated via decaying homogeneous turbulence benchmark case. Then, a channel flow problem is chosen to examine these models in attached flow situations. Finally, flow around an airfoil at low Reynolds number is solved using the shear-layer-adapted delayed DES approach only, in an aim to obtain trailing-edge noise spectrum at an observer location. Despite some log-layer mismatch over turbulent boundary layers, which is typical of most DES methods, the combined application of high-resolution numerical method and advanced DES approaches, which are implemented on a stabilized Spalart-Allmaras turbulence model, shows merit in resolution of turbulence in regions of interest.     

A remark on the paper of H. H. Schaefer Abschätzung der nichttrivalen eigenwerte stochastischer matrizen

It is shown that one of the results of Schaefer can be obtained in a more elementary way and can be improved. This is an immediate corollary of a paper of the author Duke Math. J.19, 75–91 (1952).Lothar Collatz belatedly on his 60th birthday