Anthraquinone functionalized carbon composite electrode: Application to ammonia sensing

A simple strategy has been used to covalently modify the glassy carbon spheres with anthraquinone moieties through the diazonium salt reduction. The derivatized glassy carbon spheres were used to modify the basal plane pyrolytic graphite electrode by immobilizing them on its surface and examining its electrochemical behaviour. The composite electrode has been used to detect trace level ammonia in the concentration range 5 à 10-8 to 3 à 10-5 M and it was successfully applied to detect low levels of ammonia present in natural samples like urine and soil. © 2011 Elsevier B.V. All rights reserved

A new rhodamine B based fluorometric chemodosimeter for Cu2+ ion in aqueous and cellular media

A simple, sensitive and selective fluorescent chemo dosimeter rhodamine B phenyl hydrazide (RBPH) for Cu2+ was proposed. This probe is non fluorescent and colorless but exhibits fluorescent enhancement at 580 nm and displayed color change from colorless to pink for Cu2+ in the pH range 1-6. Fluorescence microscope experimental results reveals that this chemo sensor is cell permeable and can be used for fluorescence imaging of Cu2+ ions in living cells. This probe can detect Cu2+ with good linear relationships from 10 to 100 nM with r=0.99971 then limit of detection was found to be 0.015 nM with +/- 0.91% RSD at 10 nM concentrations. 2013 Elsevier B.V. All rights reserved

Optimization and Numerical investigation of organic dye degradation using Response Surface by green synthesized ZrO2 nanoparticles and its antibacterial activity

In this work, the tetragonal Zirconium oxide (ZrO2) nanoparticles (NPs) were successfully synthesized by solution combustion method using Zirconium (IV) oxynitrate hydrate as the metal precursor and an oxidizer, Basella alba raw extract at 6000C. In this study, natural fuel is used to avoid harmful chemical fuels that may pollute the environment during combustion. The impact of the fuel-to-oxidant molar ratio on the surface morphological features of nanocrystalline zirconia particles has been documented. We investigated the Physico-chemical properties of the ZrO2 NPs via thorough characterizations like XRD, EDS, SEM, TEM, FTIR, UV-Vis, and BET. ZrO2 NPs exhibit perfect photocatalytic degradation activity towards Evans blue, a toxic dye. The influence of contact time, initial dye concentration, and pH were among the independent variables used in the study. The Response Surface Model (RSM) was used to optimize and describe the interdependencies of the different variables. The method was evaluated using the Box-Behnken design (BBD). A second-order polynomial model was used to properly understand the experimental results, and the effectiveness of the chosen model was verified by the strong agreement in determination coefficient values. ZrO2 NPs also exhibit good antibacterial activity on Gram-negative Klebsiella pneumoniae and Gram-positive bacteria, Bacillus subtilis

The control of reproductive physiology and behavior by gonadotropin-inhibitory hormone

Gonadotropin-releasing hormone (GnRH) controls the reproductive physiology and behavior of vertebrates by stimulating synthesis and release of gonadotropin from the pituitary gland. In 2000, another hypothalamic neuropeptide, gonadotropin-inhibitory hormone (GnIH), was discovered in quail and found to be an inhibiting factor for gonadotropin release. GnIH homologs are present in the brains of vertebrates, including birds, mammals, amphibians, and fish. These peptides, categorized as RF amide-related peptides (RFRPs), possess a characteristic LPXRF-amide (X = L or Q) motif at their C-termini. GnIH/RFRP precursor mRNA encodes a polypeptide that is possibly cleaved into three mature peptides in birds and two in mammals. The names of these peptides are GnIH, GnIH-related peptide-1 (GnIH-RP-1) and GnIH-RP-2 in birds, and RFRP-1 and RFRP-3 in mammals. GnIH/RFRP is synthesized in neurons of the paraventricular nucleus of the hypothalamus in birds and the dorsomedial hypothalamic area in mammals. GnIH neurons project to the median eminence, thus providing a functional neuroanatomical infrastructure to regulate anterior pituitary function. In quail, GnIH inhibits gonadal activity by decreasing synthesis and release of gonadotropin. The widespread distribution of GnIH/RFRP immunoreactive fibers in all animals tested suggests various actions within the brain. In accordance, GnIH/RFRP receptor mRNA is also expressed widely in the brain and the pituitary. GnIH/RFRP immunoreactive axon terminals are in probable contact with GnRH neurons in birds and mammals, and we recently demonstrated expression of GnIH receptor mRNA in GnRH-I and GnRH-II neurons in European starlings. Thus, GnIH/RFRP may also inhibit gonadotropin synthesis and release by inhibiting GnRH neurons in addition to having direct actions on the pituitary gland. Intracerebroventricular administration of GnIH/RFRP further inhibits reproductive behaviors in songbirds and rodents, possibly via direct actions on the GnRH system. The expression of GnIH/RFRP is regulated by melatonin which is an internal indicator of day length in vertebrates. Stress stimuli also regulate the expression of GnIH/RFRP in songbirds and rodents. Accordingly, GnIH/RFRP may serve as a transducer of environmental information and social interactions into endogenous physiology and behavior of the animal. Recently, it was shown that GnIH/RFRP and its receptor are also expressed in the gonads of birds, rodents and primates. In sum, the existing data suggest that GnIH/RFRP is an important mediator of reproductive function acting at the level of the brain, pituitary, and the gonad in birds and mammals

Voltammetric characterization of 2-methoxy-4-nitrophenyl derivatized carbon powder

Carbon powder has been functionalized with 2-methoxy-4-nitrophenyl groups by the reduction of 2-methoxy-4-nitrobenzenediazonium-1,5-naphthalenedisulfonate salt in presence of hypophosporous acid as a reducing agent. This provides an easy and inexpensive methodology to modify the carbon particle surface. This derivatization is carried out in the presence of 2-methoxy-4- nitrobenzenediazonium 1,5-naphthalenedisulfonate salt along with the carbon powder and hypophosporous acid. The electrochemical behavior of the resulting 2-methoxy-4-nitrophenyl functionalized carbon powder was characterized by immobilizing it onto basal plane pyrolytic graphite (bppg) electrode and studying its voltammetric behavior. The surface morphology of derivatized carbon powder has been examined by SEM studies which revealed that the size of the functionalized carbon particles are larger than bare carbon particles The effect of pH on peak potentials, scan rate and stability of the functionalized carbon particles has revealed that they are surface bound species. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA

Spectroscopic and thermal characterization of carbon nanotubes functionalized through diazonium salt reduction

Chemical reduction of anthraquinone diazonium chloride (Fast Red AL salt) in presence of hypophosphorous acid and carbon nanotubes results in anthraquinonyl functionalized carbon nanotubes. The surface functionalized moieties have been examined electrochemically by immobilizing them onto the surface of basal plane pyrolytic graphite electrode and studying its voltammetric behaviour. The effect of pH, and scan rate has revealed that the modified species are confined on the electrode surface. The spectroscopic characterization of the modified single walled carbon nanotubes using Fourier transform infrared spectroscopy, X-ray photoemission spectroscopy, thermogravimetric analysis and transmission electron microscopy have revealed that the modifier molecules are covalently bonded on the surface of carbon nanotubes. © 2010 Elsevier B.V. All rights reserved

Microwave-assisted functionalization of glassy carbon spheres: Electrochemical and mechanistic studies

Functionalization of glassy carbon spheres have been carried out by microwave irradiation in the presence of modifier molecules through oxidation followed by amidation reaction. The glassy carbon spheres were initially catalyzed by treating with concentrated nitric acid to introduce surface-bound carboxylic groups, and its subsequent amidation reaction in the presence of p-nitroaniline yields p-nitroanilide-functionalized substrate materials. These derivatized glassy carbon spheres have been electrochemically characterized by immobilizing them on bppg electrode and studying its voltammetric behavior. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy studies have revealed that the modifying molecules are surface bound and covalently attached on the carbon substrate. © Springer-Verlag 2009

Derivatization and characterization of functionalized carbon powder via diazonium salt reduction

Chemical reduction of 4-chloro-2-nitrobenzenediazonium chloride salt in the presence of hypophosphorous acid and carbon powder results in functionalized carbon powder with chloronitrophenyl groups attached on carbon particle surface. This type of bulk derivatization protocol is very useful and most inexpensive compared to widely used electrochemically assisted derivatization protocol. The derivatized carbon powder has been characterized by studying its Fourier transform infrared spectroscopy (FTIR) and cyclic voltammetric studies. The surface functionalized moieties have been examined electrochemically by immobilizing them onto the surface of basal plane pyrolytic graphite electrode and studying its cyclic voltammetry. The effect of pH, scan rate (v), and the peak potentials (E p) as a function of pH has revealed that the species are surface bound in nature and covalently attached on the carbon surface. The FTIR studies of the derivatized carbon powder have revealed that the modifying molecule is covalently attached on the carbon particle surface. © 2007 Springer-Verlag

Nitroazobenzene Functionalized Carbon Powder: Spectroscopic Evidence for Molecular Cleavage

Carbon powder has been functionalized with nitroazobenzene groups by the reduction of 3-methoxy-6- methyl-4- [(2-nitro-4-methylphenyl) azo] benzene diazonium zinc chloride double salt (" Fast Corinth V zinc chloride double salt") in the presence of hypophosphorous acid as a chemical reducing agent. This provides an easy and inexpensive methodology to modify the carbon particle surface. The derivatized carbon powder has been spectroscopically characterized in order to confirm the functionalization of the carbon by studying its diffuse reflectance spectroscopy (DRS) and with FTIR. The electrochemical characterization of a novel carbon powder derivatized with nitroazobenzene moieties has been studied by immobilizing onto a bppg (Basal plane pyrolytic graphite) electrode for cyclic voltammetry. The voltammetric behaviour of the azo/hydrazo groups of modified carbon at low potentials is a two-electron, two-proton redox process and is a chemically reversible reaction. The peaks observed from the voltammograms of modified carbon at higher (more negative) potentials indicated that the functionalized carbon powder undergoes reductive cleavage. © 2008 by ESG