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171.
Ana‐Maria Gurban Lucian Rotariu Virgil Emanuel Marinescu Camelia Bala 《Electroanalysis》2012,24(12):2371-2379
A ternary composite material based on Prussian blue, single‐walled carbon nanotubes and 1‐butyl‐3‐methylimidazolium hexafluorophosphate was prepared and tested for electrochemical detection of H2O2. The sensor allows amperometric detection of H2O2 at ?0.05 V, with a sensitivity of 137 mA M?1?cm?2. The nanocomposite provides a favorable microenvironment for immobilization of horseradish peroxidase (HRP). Determination of xenoestrogenic compounds was performed by enzymatic oxidation at the surface of modified screen printed biosensor in the presence of H2O2. The developed electrochemical biosensors exhibited high sensitivity, low detection limits, good operational and storage stability, for detection of 4‐t‐butylphenol, 4‐t‐octylphenol, 4‐n‐nonylphenol and 4‐n‐nonylphenol ethoxylate. 相似文献
172.
Adina Arvinte Lucian Rotariu Camelia Bala Ana Maria Gurban 《Bioelectrochemistry (Amsterdam, Netherlands)》2009,76(1-2):107
Very sensitive, low cost and reliable NADH and H2O2 sensors were realised and used for development of enzyme based biosensors. The active surface of the electrodes was modified with a nanocomposite obtained by modification of SWNT with a proper mediator: Meldola Blue (for NADH) and Prussian Blue (for H2O2). Low applied potential of − 50 mV vs. Ag/AgCl reference electrode proved the synergistic effect of nanocomposite materials towards NADH and H2O2 detection. Biosensors for malic acid and alkylphenols have been developed, using mediator-functionalised-SWNT-based electrodes and two different classes of enzymes: NAD+-dependent dehydrogenases and peroxidases. Immobilization of the enzymes was realised using a series of different procedures — adsorption, Nafion membrane, sol–gel and glutaraldehyde, in order to find the best configuration for a good operational stability. A higher sensitivity comparing with other reported biosensors of about 12.41 mA/M·cm2 was obtained for l-malic acid biosensor with enzyme immobilised in Nafion membrane. Phenol, 4-t-octylphenol and 4-n-nonylphenol were used as standard compounds for HRP based biosensor. Fast biosensor response and comparable detection limit with HPLC methods were achieved. 相似文献
173.
Bismuth silicate glasses containing lithium oxide with composition 20Li2O·(80 − x)Bi2O3·xSiO2 (5 ? x ? 70 mol%) have been prepared by melt-quench technique. Density (D), molar volume (VM) and glass transition temperature (Tg) for all the glass samples have been measured. FTIR spectroscopy has been employed to investigate the structure of these glasses in order to obtain information about the competitive role of Bi2O3 and SiO2 in the formation of glass network. The increase of SiO2 content in the glass matrix results in increasing the Si-O-Si bond angle and hence the ionicity of Si-O bond increases with decrease in Bi2O3/SiO2 ratio. The optical transmittance spectra of all the glasses have been recorded in the wavelength range 200-3300 nm. The values of optical band gap (Eg) have been determined from the cutoff wavelength of these glasses. The average electronic polarizability of oxide ion () and the optical basicity (Λth) have been estimated from the calculated values of the Eg and were found to be dependent directly on Bi2O3/SiO2 ratio. The variation in different physical parameters such as D, VM and Tg and optical parameters; viz., Eg, , Λth with Bi2O3/SiO2 ratio have been analyzed and discussed in terms of change in the glass structure. 相似文献
174.
Takami T Ye T Pathem BK Arnold DP Sugiura K Bian Y Jiang J Weiss PS 《Journal of the American Chemical Society》2010,132(46):16460-16466
We have used a scanning tunneling microscope (STM) to manipulate heteroleptic phthalocyaninato, naphthalocyaninato, and porphyrinato double-decker (DD) molecules at the liquid-solid interface between 1-phenyloctane solvent and graphite. We employed nanografting of phthalocyanines with eight octyl chains to place these molecules into a matrix of heteroleptic DD molecules; the overlayer structure is epitaxial on graphite. We have also used nanografting to place DD molecules in matrices of single-layer phthalocyanines with octyl chains. Rectangular scans with a STM at low bias voltage resulted in the removal of the adsorbed DD molecular layer and substituted the DD molecules with bilayer-stacked phthalocyanines from phenyloctane solution. Single heteroleptic DD molecules with lutetium sandwiched between naphthalocyanine and octaethylporphyrin were decomposed with voltage pulses from the probe tip; the top octaethylporphyrin ligand was removed, and the bottom naphthalocyanine ligand remained on the surface. A domain of decomposed molecules was formed within the DD molecular domain, and the boundary of the decomposed molecular domain self-cured to become rectangular. We demonstrated a molecular "sliding block puzzle" with cascades of DD molecules on the graphite surface. 相似文献
175.
K. Shadak Alee M. Bala Murali Krishna B. Ashok D. Narayana Rao 《Photonics and Nanostructures》2012,10(2):236-242
Enhancement of nonlinear absorption of polystyrene (PS) was investigated using 3D PS photonic crystals (PCs) with Z-scan technique. The Z-scan experiment was carried out at 532 nm in the picosecond (ps) regime. The transmittance of the PC was found to get modified because of the nonlinear absorption of PS particularly when 532 nm is near the photonic stop band (PSB) edge of PC. Calculations show that the field gets enhanced by 1.4 times the input field intensity within the crystal when the 532 nm wavelength falls at the PSB edge while keeping the crystal at an angle of 35°. 相似文献
176.
Houndonougbo Y Jin H Rajagopalan B Wong K Kuczera K Subramaniam B Laird B 《The journal of physical chemistry. B》2006,110(26):13195-13202
We present complementary molecular simulations and experimental results of phase equilibria for carbon dioxide expanded acetonitrile, methanol, ethanol, acetone, acetic acid, toluene, and 1-octene. The volume expansion measurements were done using a high-pressure Jerguson view cell. Molecular simulations were performed using the Gibbs ensemble Monte Carlo method. Calculations in the canonical ensemble (NVT) were performed to determine the coexistence curve of the pure solvent systems. Binary mixtures were simulated in the isobaric-isothermal distribution (NPT). Predictions of vapor-liquid equilibria of the pure components agree well with experimental data. The simulations accurately reproduced experimental data on saturated liquid and vapor densities for carbon dioxide, methanol, ethanol, acetone, acetic acid, toluene, and 1-octene. In all carbon dioxide expanded liquids (CXL's) studied, the molecular simulation results for the volume expansion of these binary mixtures were found to be as good as, and in many cases superior to, predictions based on the Peng-Robinson equation of state, demonstrating the utility of molecular simulation in the prediction of CXL phase equilibria. 相似文献
177.
178.
Flavanones have been synthesised by cyclisation of 2′-hydroxychalones with potassium ferricyanide using phase transfer catalysis. 相似文献
179.
An efficient, waste-free protocol has been developed for the synthesis of amides directly from nonactivated carboxylic acids and amines without any tedious purification. Fatty acids were also converted into corresponding amides by reaction with nonactivated amines. The synthesized amides were cyclized to tetrahydroisoquinolines in good yields. 相似文献
180.
A transition metal–free process, promoted by sodium borohydride, has been developed for convenient and selective hydration of nitriles to corresponding amides. The present process converts the aromatic, aliphatic, and heteroaromatic nitriles with wide functional group tolerance. The regioselective hydration of one nitrile moiety in the presence of an other nitrile group makes high impact in the present protocol. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.] 相似文献