Fluorescence-enhanced optical sensor for detection of Al<Subscript>3+</Subscript> in water based on functionalised nanoporous silica type SBA-15

An organic–inorganic hybrid optical sensor (PQ-SBA-15) was designed and prepared through functionalisation of the SBA-15 surface with 3-piperazinepropyltriethoxysilane followed by covalently attaching 8-hydroxyquinoline. Characterisation techniques, including FT-IR, thermal gravimetric, N2 adsorption-desorption and X-ray powder diffraction analyses, showed that the organic moieties were successfully grafted onto the surface of SBA-15 without the SBA-15 structure collapsing. The evaluation of the sensing ability of PQ-SBA-15 using fluorescence spectroscopy revealed that the PQ-SBA-15 was a selective fluorescence enhancement-based optical sensor for Al³⁺ in water in the presence of a wide range of metal cations including Na⁺, Mg²⁺, K⁺, Ca²⁺, Cr³⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺ and Pb²⁺ with a limit of detection of 8.8 × 10–7 M. In addition, good linearity was observed between the fluorescence intensity and the concentration of Al³⁺.     

An Efficient Synthesis of New 3,4-Dihydropyrimidin- 2(1H)-ones Incorporating a Phenyl Moiety at C-5 and C-6 Catalyzed by TMSCl and Co(OAc)2.4H2O

New 3,4-dihydropyrimidin-2-ones having a phenyl moiety at C-5 and C-6 have been prepared by a microwave-assisted Biginelli–like reaction by a three-component, one-pot condensation of an aromatic aldehyde, deoxybenzoin and urea, or thiourea using TMSCl and Co(OAc) ₂ .4H ₂ O as an efficient Lewis acid catalyst.     

Experimental Measurements of Densities and Viscosities of Binary and Ternary Mixtures of Benzene,Cyclohexane, and N,N-Dimethylacetamide at 298.15 K and 87 kPa

Journal of Solution Chemistry - Experimental measurements of thermophysical properties including densities (ρ) and dynamic viscosities (η) at temperature 298.15&nbsp;K and pressure...     

Sulfonated magnetic nanocatalyst and application for synthesis of novel Spiro[acridine-9,5′-thiazole]-1,4′-dione derivatives

Sulfonated Sulfurol supported Fe₃O₄ (Fe₃O₄@SiO₂-Pr-Sulfurol-SO₃H) a new magnetic reusable nanocatalyst was prepared using chemical modification of magnetic nanoparticles (MNPs) surface with Sulfurol-SO₃H. The Sulfurol-SO₃H moieties on the surface of MNPs act as acidic catalytic sites for catalysis purposes. Fe₃O₄@SiO₂-Pr-Sulfurol-SO₃H was authenticated by usual analytical and spectroscopic techniques. The prepared Fe₃O₄@SiO₂-Pr-Sulfurol-SO₃H MNPs were applied to the preparation of novel Spiro[acridine-9,5′-thiazole]-1,4′-dione derivatives via the three-component condensation of isatins, dimedone and thioamides or thioureas.

     

Inhibitory Effects of p-Phenylene-bis and Phenyl Dithiocarbamate on Mushroom Tyrosinase

The binding properties and structural changes of mushroom tyrosinase enzyme, MT, due to its interactions with phenyl dithiocarbamate (I) and p-phenylene-bis dithiocarbamate (II), were investigated at 27 and 37 °C in phosphate buffer (10?mmol?L^?1) at pH = 6.8 by isothermal titration calorimetric (ITC). The extended solvation model was used to calculate the solvation parameters, which were attributed to the stability of this enzyme. Thermodynamic analysis indicated that the predominant mode of interaction was hydrophobic in the binding of compound I to MT, while the binding of II to MT essentially depends on electrostatic interactions. It seems that II is a more potent MT inhibitor due to its two charged head groups that are able to chelate copper ions in the active enzyme site. It was concluded that MT has two distinct sites for p-phenylene-bis and phenyl dithiocarbamate.     

Simultaneous diophantine approximation in non-degenerate <Emphasis Type="Italic">p</Emphasis>-adic manifolds

An S-arithmetic Khintchine-type theorem for products of non-degenerate analytic p-adic manifolds is proved for the convergence case. In the p-adic case the divergence part is also obtained.     

A coordinating contract for transshipment in a two-company supply chain

We study a supply chain with two independent companies producing an identical product and cooperating through transshipment. Previous studies of this chain show that only under certain conditions, linear transshipment prices could be found that induce the companies to choose the first best production quantities. Moreover, even if such transshipment prices do exist, they result in a unique division of total expected profit and thus they cannot accommodate arbitrary divisions of the profit. Using the Generalized Nash Bargaining Solution, we derive coordinating transshipment prices that always give rise to a coordinating contract for the chain. This contract relies on an implicit pricing mechanism.     

Plane-strain discrete dislocation plasticity incorporating anisotropic elasticity

The increasing application of plane-strain testing at the (sub-) micron length scale of materials that comprise elastically anisotropic cubic crystals has motivated the development of an anisotropic two-dimensional discrete dislocation plasticity (2D DDP) method. The method relies on the observation that plane-strain plastic deformation of cubic crystals is possible in specific orientations when described in terms of edge dislocations on three effective slip systems. The displacement and stress fields of such dislocations in an unbounded anisotropic crystal are recapitulated, and we propose modified constitutive rules for the discrete dislocation dynamics of anisotropic single crystals. Subsequently, to handle polycrystalline problems, we follow an idea of O’Day and Curtin (J. Appl. Mech. 71 (2004) 805–815) and treat each grain as a plastic domain, and adopt superposition to determine the overall response. This method allows for a computationally efficient analysis of micro-scale size effects. As an application, we study freestanding thin copper films under plane-strain tension. First, the computational framework is validated for the special case of isotropic thin films modeled by means of a standard 2D DDP method. Next, predictions of size dependent plastic behavior in anisotropic columnar-grained thin films with varying thickness/grain size are presented and compared with the isotropic results.     

Stress concentration around a hole in a radially inhomogeneous plate

The stress concentration factor around a circular hole in an infinite plate subjected to uniform biaxial tension and pure shear is considered. The plate is made of a functionally graded material where both Young’s modulus and Poisson’s ratio vary in the radial direction. For plane stress conditions, the governing differential equation for the stress function is derived and solved. A general form for the stress concentration factor in case of biaxial tension is presented. Using a Frobenius series solution, the stress concentration factor is calculated for pure shear case. The stress concentration factor for uniaxial tension is then obtained by superposition of these two modes. The effect of nonhomogeneous stiffness and varying Poisson’s ratio upon the stress concentration factors are analyzed. A reasonable approximation in the practical range of Young’s modulus is obtained for the stress concentration factor in pure shear loading.