The Knoevenagel-Doebner reaction on 1,2-O-(2,2,2-trichloroethylidene) derivatives of D-gluco- and D-manno-furanose

The synthesis of new α,β-unsaturated furanuronic acid derivatives of α-gluco-, β-gluco- and β-manno-chloraloses via a convenient one pot procedure using the Knoevenagel-Doebner reaction approach are described. The dialdofuranose derivatives were reacted with malonic acid under Knoevenagel-Doebner reaction conditions and (E)-α,β-unsaturated furanuronic acid derivatives were obtained.     

Amperometric enzyme electrode for glucose determination based on poly(pyrrole-2-aminobenzoic acid)

Polymerization of pyrrole and 2-aminobenzoic acid has been investigated, and a functionalized stable film of poly(pyrrole-2-aminobenzoic acid) (PP2ABA) has been obtained electrochemically onto platinum electrode. Different cyclic voltammetric behavior is obtained for polypyrrole and PP2ABA during electrosynthesis. Fourier-transformed infrared spectrometry and surface-enhanced Raman spectrometry measurements on the two films have confirmed the presence of carboxylate group in the films. The enzyme, glucose oxidase, was covalently immobilized on a conducting PP2ABA film, and amperometric response was measured as a function of concentration of glucose at a potential of 0.7 V vs Ag/AgCl in 0.1 M phosphate buffer at pH 6.2. The effect of polymeric film thickness, pH, and possible interferents were investigated. The linear range of the calibration curve is from 3 to 40 mM with a sensitivity of 0.058 μA mM⁻¹ cm⁻² and a limit of detection of 0.5 mM. The apperent Mishaelis–Menten constant K _M is calculated to be 1 × 10⁻² mM, and the response time is 5 s.     

Vertical inventories and fluxes of <Superscript>210</Superscript>Pb, <Superscript>228</Superscript>Ra and <Superscript>226</Superscript>Ra at southern South China Sea and Malacca Straits

Inventories and fluxes of ²¹⁰Pb, ²²⁸Ra and ²²⁶Ra were determined in sediment cores collected at nine stations covering of the southern South China Sea and Malacca Straits with the thickness of water column between 42 and 83 m depth. The inventories of ²¹⁰Pb, ²²⁸Ra and ²²⁶Ra were calculated range from 0.15–2.55 Bq cm⁻², 0.05–0.40 Bq cm⁻² and 6.83–83.63 Bq cm⁻², meanwhile the fluxes ranged from 0.005–0.079 Bq cm⁻² yr⁻¹, 0.009–0.048 Bq cm⁻² yr⁻¹ and 0.003–0.037 Bq cm⁻² yr⁻¹, respectively. The results show that the highest inventories and fluxes for ²¹⁰Pb, ²²⁸Ra and ²²⁶Ra were found at station WC 01 and EC 05. Because there are additional sources of ²¹⁰Pb, ²²⁸Ra and ²²⁶Ra, where water transport will brings more dissolved isotopes, influence of the transportation and deposition of suspended particles, fast rate of regeneration and greater production of those radionuclides and others.     

Broad bandwidth SOA-based multiwavelength laser incorporating a bidirectional Lyot filter

We demonstrate a broad bandwidth multiwavelength laser based on a bidirectional Lyot filter and a semiconductor optical amplifier with a mechanism of intensity-dependent loss as the flatness agent. A wide bandwidth of a multiwavelength spectrum of 32.9 nm within a 5 dB uniformity is obtained under optimized polarization parameters. For this case, the number of generated lasing lines is 329 with a fixed wavelength separation of 0.1 nm. The power stability of this multiwavelength laser is less than 1.35 dB within 200 min time frame. This shows that the bidirectional Lyot filter provides an alternative option for multiwavelength generation in laser systems.     

Electrical and transport properties of NH4Br-doped cornstarch-based solid biopolymer electrolyte

Ionics - In this work, cornstarch-based electrolytes are doped with ammonium bromide (NH4Br) and plasticized with glycerol. Starch-NH4Br complexation is evidenced from the Fourier transform...     

Responses of Pt/n-InP Schottky diode to electron irradiation in different temperature conditions

Different radiation and temperature effects on Schottky diodes are technologically important from radiation to sensing applications. We discussed irradiation and temperature dependent electronic properties of Pt/n-InP Schottky contact. Firstly we fabricated Pt/n-InP Schottky diode by magnetron sputtering technique. Then sample was exposed to 12 MeV electron irradiation. We measured I–V characteristics in 20, 160, 300 and 400 K before and after irradiation. Changes in forward currents for 160, 300 and 400 K were not remarkable but irradiation was effective only in 20 K slightly. Reverse currents of Pt/n-InP Schottky diode were increased in 20, 160, 300 and 400 K by irradiation.     

Investigation of counterion influence on an octahedral IrH6-complex in the solid state hydrides AAeIrH6 (A = Na, K and Ae = Ca, Sr, Ba, and Eu) with a new structure type

A number of new quaternary iridium based hydrides and deuterides AAeIrH/D(6) (where A = Na and K; Ae = Ca, Ba, Sr, and Eu) have been synthesized by direct combination of the alkali, alkaline earth or europium binary hydrides/deuterides and iridium powder. The crystal structures were determined by Guinier-H?gg X-ray and neutron powder diffraction and a new cubic structure type was found. The structure is described in space group F43m, but related to the K(2)PtCl(6) type structure. The new structure can be described as consisting of cubes of A(+) and Ae(2+) ions, where the A(+) and Ae(2+) ions alternates so that they occupy opposite corners in the cube. Every second cube contains a regular octahedral [Ir(III)H(6)](-3)-complex and the adjacent is empty. Solid-state IR spectroscopy was used to determine the Ir-allowed stretching and bending frequencies for the [Ir(III)H(6)](-3) complex with different counterions. These were also compared with the corresponding stretching frequencies for Fe(II)H(6), Ru(II)H(6), Os(II)H(6), and Ir(II)H(5) complexes in similar solid state hydrides, which increased when going from Fe through Ru, Os to Ir. The frequencies scaled almost linearly with the inverse of size of the cube surrounding the complexes but showed no significant dependence of the formal oxidation state or the experimentally obtained Ir-D distances. However, this was mainly because of difficulties in obtaining enough accurate atomic positions. The ab initio DFT calculations could reproduce the stretching frequencies within a few 10 cm(-1), indicating that experimental vibrational frequencies offer a sensitive test of DFT results.     

Preparation, characterisation, and dielectric properties of polypyrrole-clay composites

In this study, polypyrrole-clay (PPy-clay) composites were prepared by the in situ chemical oxidative polymerisation of pyrrole in the presence of clay. The chemical structures of the composites were characterised by FTIR and XRD analysis. The thermal properties of these novel composites were analysed by TGA and DSC measurements. Glass-transition temperatures and char yields increased with the increase in clay content in the nanocomposites. The interactions between PPy and clay were mainly between polypyrrole and the layers of clay. It was observed that, as the amount of clay in the composites increased, the dielectric permittivity decreased while the dielectric conductivity of the composite materials increased.     

Development of antimicrobial cotton fabric using bionanocomposites

In order to provide antimicrobial activity to cotton, cotton fabrics were treated by montmorillonite (KSF), montmorillonite–dihydroxy ethylene urea (KSF–MDEU), KSF–chitosan (CS) and KSF–CS–MDEU solutions containing 12.5, 25 and 50 ppm silver ion. The effect of modification on the antibacterial activity of cotton fabrics was also evaluated after 10 cycles of washings. MDEU exhibited better antimicrobial activities after washing process. By using 25 ppm silver, KSF and CS modification solution, good performance in terms of antibacterial activity was obtained. The addition of CS and MDEU increased the whiteness index values of cotton fabrics treated with KSF containing different silver concentrations. The characterization of modified cotton samples was done by Fourier transform infrared spectroscopy, X-ray diffraction analysis, inductively coupled plasma-mass spectroscopy, scanning electron microscopy and thermogravimetric analysis.     

A New Model for The Formation of Mini Black Holes

A new model different from the Hawking model is suggested to describe the formation of mini (primordial) black holes. It is based on an idea that the fluids, which fill in the universe at the beginning just after the big bang, are separated into mini clusters, moving with supersonic velocities and colliding with each other under the forces of gravitational attractions. We show that between the time era from 10^–43 to 10^–8 sec. about 36 various generations of mini black holes with masses ranging in the interval 10^–5—10^–30 gm are possible.