A novel dual channel responsive zinc(II) probe

A novel compound, 1, which is based on a 1,10-phenanthroline scaffold with cofacial BODIPY units, is synthesized via a three-step reaction sequence. It is noteworthy that 1 can be utilized for both visual and turn-off fluorometric detection of Zn²⁺ ions in aqueous acetonitrile solution. The fluorescence response is based on cation-mediated oxidative photoinduced electron transfer (PET). The digital action of a two-input NOR logic gate is also demonstrated.     

Ammonium O,O‐dicyclo­hexyl phosphoro­dithio­ate

The structure of the title compound, NH₄⁺·C₁₂H₂₂O₂PS₂⁻, consists of a polymeric arrangement of ammonium cations and O,O‐dicyclohexyl phosphorodithioate anions linked through N—H⋯O and N—H⋯S hydrogen bonds. These inter­actions result in the formation of (100) sheets.     

Nonlinear effects in proline–thiourea host–guest complex catalyzed aldol reactions in nonpolar solvents

An aldol reaction catalyzed by a proline–thiourea host–guest complex in a nonpolar solvent shows excellent nonlinear effects. This proline–thiourea system has the ability to form a hydrogen-bonding network. The enantiomeric excess of proline in a solution can be significantly enhanced by its incorporation with a urea molecule into its solid racemate. This suggests a general and facile route to homochirality, which may be involved in the origin of chirality on earth.     

Surface wave scattering by a rectangular impedance cylinder located on a reactive plane

The electromagnetic scattering of the surface wave by a rectangular impedance cylinder located on an infinite reactive plane is considered for the case that the impedances of the horizontal and vertical sides of the cylinder can have different values. Firstly, the diffraction problem is reduced into a modified Wiener–Hopf equation of the third kind and then solved approximately. The solution contains branch‐cut integrals and two infinite sets of constants satisfying two infinite systems of linear algebraic equations. The approximate analytical or numerical evaluations of corresponding integrals and numerical solution of the linear algebraic equation systems are obtained for various values of parameters such as the surface reactance of the plane, the vertical and horizontal wall impedances, the width and the height of the cylinder. Copyright © 2004 John Wiley & Sons, Ltd.     

Diacetatobis(2‐amino­benzothia­zole‐κN)cobalt(II)

The title complex, [Co(C₂H₃O₂)₂(C₇H₆N₂S)₂], contains a Co centre with a slightly distorted tetra­hedral coordination geometry, involving two acetate ligands and two N atoms from the thia­zole moiety [Co—O = 2.0025 (14) and 1.9953 (16) Å, and Co—N = 2.0524 (18) and 2.0568 (18) Å]. The inter­planar angle between the two benzothia­zole moieties is 77.86 (3)°. The amine groups, acting as donors, participate in intra‐ and inter­molecular N—H⋯O hydrogen bonds, with N⋯O distances in the range 2.806 (2)–2.857 (2) Å.     

Weak maximum principle for optimal control problems of nonsmooth systems

In this paper, by considering vector-valued maximum type functions satisfying Lipschitz condition, and optimal control systems with continuous-time which is governed by systems of ordinary differential equation, we derive results similar to Pontryagin’s maximum principle and properties concerning the generalized Jacobian set for optimal control problems of these systems.     

On the mean and extreme distances between failures in Markovian binary sequences

This paper is concerned with the mean, minimum and maximum distances between two successive failures in a binary sequence consisting of Markov dependent elements. These random variables are potentially useful for the analysis of the frequency of critical events occurring in certain stochastic processes. Exact distributions of these random variables are derived via combinatorial techniques and illustrative numerical results are presented.     

Utilization of smart hydrogel-metal composites as catalysis media

Various metal nanoparticles such as, Cu, Co, Ni, and Fe were prepared inside poly(1-vinyl imidazole) p(VI) hydrogel by the absorption of the corresponding metal ions from aqueous solutions and the reduction with suitable reducing agents such as NaBH(4) and/or NaOH. TGA and ICP-AES were used to determine the metal particle content of p(VI)-M (M: Cu, Co, and Ni) composites. The prepared hydrogel-metal nanoparticle composites were proven to be resourceful as reaction container for the catalysis of various organic reactions. It was illustrated that p(VI)-M hydrogel-metal composites can be successfully used in the hydrolysis of NaBH(4) for the generation hydrogen form NaBH(4) and NH(3)BH(3). Additionally, p(VI)-M composites were also illustrated in the catalysis of different organic reactions; e.g., these hydrogel-M are very effective in the reduction nitro aromatic compounds such 2-nitrophenol (2-NP) and 4-nitrophenol (4-NP) to their corresponding amine forms in the presence of aqueous NaBH(4). Various parameters in the catalysis of hydrogen production and 4-NP reduction were determined.     

Theoretical demonstration of the hybrid focusing points of sonic crystal flat lenses and possible applications

We demonstrate the hybrid focusing points of sonic crystals for a multi-source array applied to flat sonic crystal lenses. The contributions of different point source couples form hybrid focusing points. Ray-trace analyses are conducted for acoustic flat lenses with multi-source configurations. The finite-difference time-domain (FDTD) simulation of flat lenses with multi-source configurations demonstrates the establishment of pure and hybrid focusing points in a pyramidal constellation. The number of focusing points in the pyramidal constellation depends on the number of point sources. We propose an acoustic device for fine-tuning the location of a far-field hybrid focusing point and discuss its benefits for acoustic energy focusing application.