Some remarks on global asymptotic stability of neural networks with constant time delay

An elegant proof of a previously reported criterion for the uniqueness and global asymptotic stability of the equilibrium point of a class of neural networks with constant time delay is presented. The present proof yields some interesting observations.     

Chemistry of N,N-Dimethylaminoalkylchalcogenolate Complexes of Palladium(II) and Platinum(II)

Abstract

Four different series of N,N-dimethylaminoalkylchalcogenolates, viz. Me₂NCH₂ CH₂E^?, Me₂NCH(Me)CH₂E^?, Me₂NCH₂CH(Me)E^?, and Me₂NCH₂CH₂CH₂E^? (E = S, Se, Te), (referred as E^∩N) have been synthesized and characterized. Their reactions with palladium(II) and platinum(II) precursors have been explored. Complexes of the general formula, [MCl(E^∩N)]_n, [MCl(E^∩N)₂]_n, [MCl(E^∩N)(PR₃)], [M₂Cl₂(μ-E^∩N)₂(PR₃)₂], [M₂(μ-E^∩N)₂(P^∩P)₂]²⁺, etc. have been isolated. All the complexes have been characterized by elemental analysis, IR, NMR (¹H, ¹³C, ³¹P, ⁷⁷Se, ¹²⁵Te, ¹⁹⁵Pt), UV-vis, and FAB mass spectral data. A weak absorption in the electronic spectra of [MCl(E^∩N)(PR₃)] has been attributed to metal mediated ligand-to-ligand charge transfer and showed pronounced chalcogen dependence being red shifted on moving from S → Se → Te. Structures of several complexes have been established by X-ray diffraction analyses. Thermal behavior of some of these complexes has been investigated by TGA.     

New global robust stability results for delayed cellular neural networks based on norm-bounded uncertainties

A new linear matrix inequality based approach to the uniqueness and global asymptotic stability of the equilibrium point of uncertain cellular neural networks with delay is presented. The uncertainties are assumed to be norm-bounded. A new type of Lyapunov–Krasovskii functional is employed to derive the result.     

Synthesis and characterization of methylpalladium(II) dithiolate complexes of the type [PdMe(SS)(ER3)] (SS = S2CNR 2, S2COEt, S2P(OR)2, S2 PPh2; ER3 = PMePh2, PPh3, AsPh3)

Methylpalladium(II) dithiolate complexes of the type [PdMe(SS)(ER₃] (SS = S₂ CNR₂ (R = Me or Et), S₂COEt, S₂P(OR)₂ (R = Et, ⁿPr, ⁱPr), S₂PPh₂; ER₃ = PMePh₂, PPh₃, AsPh₃) have been synthesized by the reaction of [Pd₂Me₂(μ-Cl)₂(PMePh₂)₂] with sodium/potassium/ammonium salts of the dithio acid or by treatment of [PdMeCl(cod)] with ER₃ followed by sodium/potassium/ammonium salts of the dithio ligand. All the complexes were characterized by elemental analysis, IR and nuclear magnetic resonance (¹H, ³¹P) data.     

Electrochemically Deposited Porous Graphene−Polypyrrole−Polyphenol Oxidase for Dopamine Biosensor

We report a method for the fabrication of glassy carbon electrode modified porous graphene-polypyrrole-polyphenol oxidase (GCE−PG−PPy−PPO) modified electrode for the determination dopamine. The optimization of pH, concentration and detection limit of dopamine was employed by amperomatric technique. The detection limit of dopamine was found to be in a linear range of 2×10⁻⁸ to 4.6×10⁻⁵ M and lower limit detection is 4×10⁻⁹ M. Michealis – Menten constant (Km) and the activation energy were calculated as 31.32 μM and 37.4−Kj mol⁻¹, respectively. The developed biosensor was used to quantify the dopamine in human urine sample.     

Retinal phosphenes and discrete dark noises in rods: A new biophysical framework

Spontaneous rhodopsin activation produces discrete noises indistinguishable from single-photon responses. However, there is a serious discrepancy between the apparent energy barrier of thermal events compared with that of the photon-driven process. Current estimates of the activation energies of discrete dark noises in vertebrate rod and cone pigments are 40–50 kcal/mol for activation by photon and 20–25 kcal/mol for activation by heat. To reconcile this discrepancy, it was assumed that thermal activation and photon activation of rhodopsin follow different molecular mechanisms. The most convincing hypothesis for a separate low-energy thermal pathway is that the discrete dark noises of rods arise in a small subpopulation of rhodopsins, where the Schiff base linking the chromophore to the protein part has been deprotonated.According to Narici et al.’ experiments (2009, Radiation Measurements), phosphene perception in space travel is due to the ionizing radiation-induced free radicals that generate chemiluminescent photons from lipid peroxidation. These photons are absorbed by the photoreceptors chromophores, which modify the rhodopsin molecules (bleaching) and start the photo-transduction cascade resulting in the perception of phosphenes.Here, we point out that not only retinal phosphenes but also the discrete dark noise of rods can be due to the natural redox related (free radical) bioluminescent photons in the retina. In other words, under regulated conditions, lipid peroxidation is a natural process in cells and also in retinal membranes. Since the natural lipid peroxidation is one of the main sources of bioluminescent photons and the photoreceptors have the highest oxygen demand and polyunsaturated fatty acid (PUFA) concentration, there is a continuous, low level bioluminescent photon emission in the retina without any external photonic stimulation. During photopic or scotopic vision, evanescent bioluminescent photon emission is negligible. In contrast, in dark-adapted retinal cells this evanescent bioluminescent photon emission is not negligible. Therefore, our hypothesis is that the discrete dark noise of rods can be due to these bioluminescent photons.     

A tripodal receptor bearing catechol groups for the chromogenic sensing of F ions via frozen proton transfer

A neutral tripodal Schiff base receptor (3) having catechol as end groups has been synthesized and characterized with the help of spectroscopic and single crystal X-ray crystallographic studies. The receptor behaves as a visually detectable optical sensor for F⁻ ions in DMSO, sensitive enough to recognize the ions up to a concentration 1×10⁻⁵ M with naked eye. The chromogenic response is based upon the deprotonation of the highly acidic catechol moieties in the presence of highly basic F⁻ ions in a polar solvent like DMSO.     

Synthesis of 2,5-disubstituted tetrazoles as possible antiinflammatory agents

Several 2-(1-acetoxy-3-substituted carbamido)-5-phenyltetrazoles were synthesized as possible antiinflammatory agents. Nmr spectroscopy was used as a tool in assigning the structure of the. Positional isomers of these substituted phenyltelrazoles. Compounds possessing antiinflammatory activity (100 mg./kg., i.p.) provided 11–41% protection against carrageenin-induced edema in rats. Seven of these substituted phenyltelrazoles possessed antiproteolytic activity and the in vitro inhibition of trypsin activity during hydrolysis of bovine serum albumin ranged from 9–66%.     

Preparation and characterization of tris(iso‐propyl)stibine complexes of palladium and platinum

Tris(iso‐propyl)stibine complexes of palladium and platinum of the type [MX₂(SbⁱPr₃)₂] [M, X = Pd, Cl (1a), Pd, Br (1b), Pd, I (1c), Pt, Cl (2)] have been prepared and characterized by elemental analysis, IR and ¹H NMR spectral data. The structure of 1a, established by X‐ray structural analysis, revealed that the palladium atom is in a square planar environment with mutually trans SbⁱPr₃ ligands. Copyright © 2001 John Wiley & Sons, Ltd.     

The chemistry of binuclear palladium(II) and platinum(II) complexes

The chemistry of binuclear palladium(II) and platinum(II) complexes has been reviewed. This review deals with complexes derived from various classes of ligands and covers various aspects, viz. synthesis, spectroscopic and structural features and chemical reactivity, of these complexes. Applications of these complexes are briefly described in the respected sections.