Aptamer-based determination of ATP by using a functionalized impedimetric nanosensor and mediation by a triangular junction transducer

Microchimica Acta - The authors describe an impedimetric nanosensor for aptamer-mediated detection of ATP. A triangular junction of polysilicon substrate is used as a transducer. The aptamer was...     

Synthesis and characterization of 1,3-bis(2-hydroxyethoxy) benzene based saturated and unsaturated polyesters

Polyesterification of adipic acid and maleic anhydride with 1,3-bis(2-hydroxyethoxy)benzene (HER) in the presence of toluene-4-sulphonic acid was carried out using melt condensation technique. The structural characterization of the synthesized polyesters had been carried out using Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (¹H NMR) spectroscopic methods. The thermal properties of the polyesters were studied using differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The activation energies for the thermal degradation of the polyesters were calculated by the method of Dharwadkar and Kharkhanavala and discussed. The char residue value at 600 °C indicated maleic anhydride based polyester is thermally more stable compared to the adipic acid based polyester. The mechanism of degradation of these polyesters is discussed.     

The dithiolene ligand and tetrathiafulvalene precursor molecules 4,5‐bis(bromomethyl)‐1,3‐dithiol‐2‐one and 4,5‐bis[(dihydroxyphosphoryl)methyl]‐1,3‐dithiol‐2‐one

The crystal structures of 4,5‐bis(bromomethyl)‐1,3‐dithiol‐2‐one, C₅H₄Br₂OS₂, (I), and 4,5‐bis[(dihydroxyphosphoryl)methyl]‐1,3‐dithiol‐2‐one, C₅H₈O₇P₂S₂, (II), occur with similar unit cells in the same monoclinic space group. Both molecules reside on a twofold symmetry axis coincident with the C=O bond, so that the substituents in the 4‐ and 5‐positions project above and below the plane of the 1,3‐dithiol‐2‐one ring. In both structures, the molecules align themselves in a head‐to‐tail fashion along the b axis, and these rows of molecules then stack, with alternating directionality, along the c axis. For (II), an extensive network of intermolecular hydrogen bonds occurs between molecules within the same stack and between adjacent stacks. Each –CH₂P(O)(OH)₂ group participates in four hydrogen bonds, twice as donor and twice as acceptor.     

Oxovanadium(IV)‐Salen Ion Catalyzed H2O2 Oxidation of Tertiary Amines to N‐Oxides– Critical Role of Acetate Ion as External Axial Ligand

The oxovanadium(IV)‐salen ion catalyzed H₂O₂ oxidation of N,N‐dimethylaniline forms N‐oxide as the product of the reaction. The reaction follows Michaelis–Menten kinetics and the rate of the reaction is accelerated by electron donating groups present in the substrate as well as in the salen ligand. This peculiar substituent effect is accounted for in terms of rate determining bond formation between peroxo bond of the oxidant and the N‐atom of the substrate in the transition state. Trichloroacetic acid (TCA) shifts the λ_max value of the oxidant to the red region and catalyzes reaction enormously. The cleavage of N? O bond by vanadium complex leads to moderate yield of the product. But the percentage yield of the product becomes excellent in the presence of TCA.     

Biocatalytic deracemization of alkyl-2-hydroxy-4-arylbut-3-ynoates using whole cells of Candida parapsilosis ATCC 7330

Racemic alkyl-2-hydroxy-4-arylbut-3-ynoates were deracemized to the (S)-alkyl-2-hydroxy-4-arylbut-3-ynoates in excellent enantiomeric excesses (up to >99%) and good isolated yields (up to 81%) with the biocatalyst Candida parapsilosis ATCC 7330. The absolute configuration of the resulting enantiomer was assigned by ¹H NMR using Mosher’s method.     

Suppression of electron correlations in the superconducting alloys of Rh17−xIrxS15

We have studied the effect of Iridium doping (Rh_17?xIr_xS₁₅) in the rhodium sites of the strongly correlated superconductor Rh₁₇S₁₅. Even at low levels of doping (x = 1 and 2) we see a drastic change in the superconducting properties as compared to those of the undoped system. We deduce that there is a reduction in the density of states at the Fermi level from reduced Pauli susceptibility and Sommerfeld coefficient in the doped samples. Moreover, the second magnetization peak in the isothermal magnetization scan (‘fishtail’) which was very prominent in the magnetization data of the undoped crystal is suppressed in the doped samples. The temperature dependence of resistivity of the doped crystals show a remarkably different behavior from that of the undoped crystal with the appearance of a minima at lower temperatures, the position of which is fairly constant at different fields. Our data supports the notion that Iridium, which is a bigger atom than rhodium expands the lattice thereby, reduces the electron correlations that existed due to the interaction between closer lying rhodium atoms in the undoped system.     

Allocating flexible servers in serial systems with switching costs

Consider a firm that operates a make-to-order serial production system and employs a cross-trained workforce. We model such a firm as a tandem queuing system in which flexible servers can be allocated across stations, and assume that a switching cost is charged when servers move between stations. We show that even in the two-station two-server case the optimal policy follows a complex state-dependent structure that may be difficult to implement in practice. We propose three alternate heuristic policies and assess their performance. We show that a simpler policy which only moves one server can achieve close to optimal results.     

From ribbons to nanodot arrays: nanopattern design through reductive annealing

A new approach to the generation of nanoparticle arrays in periodic as well as non-periodic fashions has been discovered based on reduction of oxidized nanoscroll/nanoribbon precursors in the transmission electron microscope (carbothermal reduction) or by hydrogen annealing. Arrays consisting of nickel arsenide nanoparticles of size 3-4 nm have been generated.