Facile immobilization of potassium-copper hexacyanoferrate nanoparticles using a room-temperature ionic liquid as an ionic binder and its application towards BHA determination

In this paper, a facile immobilization of copper hexacyanoferrate nanoparticles (CuHCFNP) on a paraffin wax-impregnated graphite electrode (PIGE) was carried out using the room-temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF₄) as an ionic binder. The characteristics of the CuHCFNP/EMIMBF₄ gel-modified electrode were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques, and the modified electrode morphology was also characterized using field emission scanning electron microscopy (FESEM). The electrocatalytic behavior of butylated hydroxyl anisole (BHA) at the modified electrode has been investigated in 0.1 M KNO₃ in static and dynamic conditions. Under the optimum conditions, the oxidation peak current was proportional to the BHA concentration in the range from 1.5 to 1000 μM with a detection limit of 0.5 μM (S/N = 3). The proposed method was applied to determine BHA content in real samples with satisfactory results.

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Synthesis and characterization of immobilized activated carbon doped TiO2 thin films

Immobilized activated carbon doped TiO₂ thin films were prepared by sol–gel dip coating method by using Titanium IV isopropoxide as a precursor. Aim of our work is to synthesize and investigate the structural, surface morphology and optical properties of the synthesized thin film. X-ray diffraction pattern reveals that the crystallinity of the film increases with increase in temperature. Also, the structural parameters such as particle size, microstrain and dislocation density have been calculated. The formation of nanosphere of diameter ranging from 300 nm to 500 nm has been confirmed by Scanning electron microscope. Photocatalytic active large optical band gap at 3.75 eV was found by using UV–visible sspectrum.     

Scaffold tailoring by a newly detected Pictet-Spenglerase activity of strictosidine synthase: from the common tryptoline skeleton to the rare piperazino-indole framework

The Pictet-Spenglerase strictosidine synthase (STR1) has been recognized as a key enzyme in the biosynthesis of some 2000 indole alkaloids in plants, some with high therapeutic value. In this study, a novel function of STR1 has been detected which allows for the first time a simple enzymatic synthesis of the strictosidine analogue 3 harboring the piperazino[1,2-a]indole (PI) scaffold and to switch from the common tryptoline (hydrogenated carboline) to the rare PI skeleton. Insight into the reaction is provided by X-ray crystal analysis and modeling of STR1 ligand complexes. STR1 presently provides exclusively access to 3 and can act as a source to generate by chemoenzymatic approaches libraries of this novel class of alkaloids which may have new biological activities. Synthetic or natural monoterpenoid alkaloids with the PI core have not been reported before.     

"Turn on" electron-transfer-based selective detection of ascorbic acid via copper complexes immobilized on glass

"Turn-on" optical detection of parts-per-million (ppm) levels of ascorbic acid (AA) in water has been determined using a redox-active monolayer on glass.     

Shape changing collisions of optical solitons, universal logic gates and partially coherent solitons in coupled nonlinear Schrödinger equations

Coupled nonlinear Schrödinger equations (CNLS) very often represent wave propagation in optical media such as multicore fibers, photorefractive materials and so on. We consider specifically the pulse propagation in integrable CNLS equations (generalized Manakov systems). We point out that these systems possess novel exact soliton type pulses which are shape changing under collision leading to an intensity redistribution. The shape changes correspond to linear fractional transformations allowing for the possibility of construction of logic gates and Turing equivalent all optical computers in homogeneous bulk media as shown by Steiglitz recently. Special cases of such solitons correspond to the recently much discussed partially coherent stationary solitons (PCS). In this paper, we review critically the recent developments regarding the above properties with particular reference to 2-CNLS.     

Experimental investigations on plasticized PMMA/PVA polymer blend electrolytes

Blend based polymer electrolytes composed of poly (methyl methacrylate) (PMMA), poly(vinylalcohol) (PVA) and LiClO₄ are prepared using solvent casting technique. The polymer films are characterized by XRD and FTIR studies to determine the molecular environment for the conducting ions. These polymer films have been investigated in terms of ionic conductivity using the results of impedance studies. The influence of the blend composition on the electrochemical behaviour is also discussed. The highest room temperature conductivity obtained for the film consisting of PMMA, PVA, LiClO₄ and DMP is 0.06×10⁻³ S/cm at 303 K. The PMMA-PVA blend based polymer electrolytes look very desirable and promising for lithium battery applications.     

Synthesis and Structural Proof of a Potent 5-Lipoxygenase Inhibitor

Abstract  

5-Lipoxygenase inhibitor 3-O-acetyl-9,11-dehydro-β-boswellic acid was detected in the extract of Boswellia serrata gum resulting from unstable 11-hydroxy precursor. It was reported more potent than other Boswellic acids in its inhibition of 5-Lipoxygenase. Here, we report the method of conversion of 3-acetoxy-β-boswellic acid to 3-O-acetyl-9,11-dehydro-β-boswellic acid, and the crystal structure of later. This compound crystallizes in orthorhombic space group P2₁2₁2₁ with cell parameters of a = 12.726(1) ?, b = 16.597(1) ?, c = 27.332(2) ?, α = β = γ = 90°, V = 5772.7(5) ?³, D _c = 1.143 Mg/m³, and Z = 8. The X-ray structure investigation indicates that the rings A, B, D and E are exhibit chair and the ring C adopts a distorted half chair conformation. The conformational difference of the two structures in the arrangement is due to crystal packing of 3-O-acetyl-9,11-dehydro-β-boswellic acid. The molecular packing is stabilized by C–H···O and O–H···O types of hydrogen bonding interactions.     

Effect of phase shift in shape changing collision of solitons in coupled nonlinear Schrödinger equations

Soliton interactions in systems modelled by coupled nonlinear Schr?dinger (CNLS) equations and encountered in phenomena such as wave propagation in optical fibers and photorefractive media possess unusual features: shape changing intensity redistributions, amplitude dependent phase shifts and relative separation distances. We demonstrate these properties in the case of integrable 2-CNLS equations. As a simple example, we consider the stationary two-soliton solution which is equivalent to the so-called partially coherent soliton (PCS) solution discussed much in the recent literature. Received 1st October 2001 / Received in final form 4 February 2002 Published online 2 October 2002 RID="a" ID="a"e-mail: lakshman@bdu.ernet.in     

Studies on poly(vinyl pyrrolidone) based solid polymer blend electrolytes complexed with various lithium salts

Solid polymer electrolytes (SPEs) with high ionic conductivity and acceptable mechanical properties are of particular interest for increasing the performance of batteries. In the present work, SPEs based on poly(ethylene oxide)/poly (vinyl pyrrolidone) (PEO/PVP) with various lithium salts were prepared by solvent casting technique. The amorphous nature of the polymer-salt complex was studied by X-ray diffraction analysis. The complexation of the prepared electrolytes was confirmed by Fourier transform infrared analysis. Ionic conductivity as a function of frequency was studied at various temperatures in the range of 303–353 K. The maximum ionic conductivity value was found to be 1.08 × 10^?5 S/cm for the film containing lithium bis trifluoromethane sulfonoimide (LiN[CF₃SO₂]₂) at room temperature and the temperature dependent ionic conductivity values seem to obey Vogel-Tamman-Fulcher relation. Thermogravimetry was used to ascertain the thermal stability of the electrolytes. Photoluminescence measurements demonstrated that the sample having maximum ionic conductivity shows the minimum luminescence intensity. Ultra violet-visible analysis reveals that the values of the band gap energies were changed with the addition of various lithium salts. Porosity of the sample containing lithium bis trifluoromethane sulfonoimide (LiN[CF₃SO₂]₂) was studied by Atomic force microscope.