Synthesis of PtNPs/AQ/Ru(bpy)(3)(2+) colloid and its application as a sensitive solid-state electrochemiluminescence sensor material

The facile synthesis of the novel platinum nanoparticles/Eastman AQ55D/ruthenium(II) tris( bipyridine) (PtNPs/ AQ/Ru(bpy)(3)(2+)) colloidal material for ultrasensitive ECL solid-state sensors was reported for the first time. The cation ion-exchanger AQ was used not only to immobilize ECL active species Ru(bpy)(3)(2+) but also as the dispersant of PtNPs. Colloidal characterization was accomplished by transmission electron microscopy (TEM), X-ray photoelectron spectrum (XPS), and UV-vis spectroscopy. Directly coating the as-prepared colloid on the surface of a glassy carbon electrode produces an electrochemiluminescence (ECL) sensor. The electronic conductivity and electroactivity of PtNPs in composite film made the sensor exhibit faster electron transfer, higher ECL intensity of Ru(bpy)(3)(2+), and a shorter equilibration time than Ru(bpy)(3)(2+) immobilized in pure AQ film. Furthermore, it was demonstrated that the combination of PtNPs and permselective cation exchanger made the sensor exhibite excellent ECL behavior and stability and a very low limit of detection (1 x 10(-15) M) of tripropylamine with application prospects in bioanalysis. This method was very simple, effective, and low cost.

Voltammetric study of the sodium ion transfer across micro-water/1,2-dichloroethane interface facilitated by terminal-vinyl liquid crystal crown ether

Sodium ion transfer across micro-water/1,2-dichloroethane (DCE) interface facilitated by a novel ionophore, terminal-vinyl liquid crystal crown ether (LCCE) was studied by cyclic voltammetry. LCCEs have potential applications because of their physicochemical properties and the utilization of crown ethers as selective ionophoric units in other functionalized compounds are interesting. Host-guest-type behavior for such compounds in the liquid-crystalline state is studied. The experimental results suggest that the transfer of the sodium ion facilitated by LCCE was controlled by diffusion of LCCE from bulk solution of DCE to the interface. The diffusion coefficient of LCCE in DCE was calculated to be equal to (3.62 +/- 0.20) x 10(-6) cm(2)/s. Steady-state voltammograms are due to sodium ion transfer facilitated by the formation of 1: 1 metal (M)-LCCE complex at the interface and the mechanism tends to be transfer by interfacial complexation or dissociation (TIC or TID). The stability constant of the complex formed was determined to be log beta(o) = 5.5 in DCE phase. The influence of parameters such as concentration of sodium ion and concentration of LCCE on the sodium ion transfer was investigated.

An electrochemical study of prussian blue microcrystallines mixed in PEO400 polymer electrolyte by solid-state voltammetry

The electrochemistry of Prussian blue mixed in a polymer medium containing MClO4 (M = Li+, Na+, K+, TBA(+)) as the supporting electrolyte was studied by means of solid-state voltammetry. This approach is new in Prussian blue studies. The behavior of PB in polymer electrolytes is somewhat similar to the well-known behavior for an electrochemically synthesized PB film in aqueous media. Besides, K+, Li+ and Na+ ions can also transport through the crystal of PB because of its zeolitic nature. The transport of TBA(+) ions is possible. Kinetic control lies in the diffusion of cations in and out of the lattice of Prussian blue. Reduction waves of Prussian blue depend on both the size and type of cations. PB is very stable upon electrochemical cycling in polymer electrolytes and air. This system may be used in rechargeable batteries and electrochromic devices.

A new solid-state electrolyte: Rubbery 'polymer-in-salt' containing LiN(CF3SO2)(2)

A new class of rubbery 'polymer-in-salt' electrolytes for application in solid-state lithium batteries has been explored by differential scanning calorimetry and a.c. impedance analysis. Simple phase diagrams of LiN(CF3SO2)(2)+LiClO4 and LiC(CF3SO2)(3)+LiN(CF3SO2)(2) have been drawn, which are very important to determine polymer-in-salt electrolyte materials. The conductivities obtained by a.c. impedance measurement are smaller for the electrolyte that contains acetate LiOAc salt than for the electrolyte without this salt.

SOLID-STATE VOLTAMMETRY OF ELECTROACTIVE SOLUTES IN POLYMER SOLVENTS (PEO) AT ULTRAMICROELECTRODES

This paper describes the electrochemical oxidation and reduction of electroactive solutes which are dissolved in and diffusing through the polymer electrolyte solvent, poly(ethylene oxide) (PEO). The characteristics of electrochemical reactions in polymeric solutions are discussed, including how rigid solvent environments affect mass transport rates, and the transport phenomenon of electroactive species in PEO with bathing gases is explained by using the voltammetric theory of ultramicroelectrodes. The possibility that the microelectrode coated with PEO film can be used as a gas sensor has been discussed.

Solid-state analysis of low-melting 1,3-dialkylimidazolium hexafluorophosphate salts (ionic liquids) by combined x-ray crystallographic and computational analyses

The interactions of ions in the solid state for a series of representative 1,3-dialkylimidazolium hexafluorophosphate salts (either ionic liquids or closely related) have been examined by crystallographic analysis, combined with the theoretical estimation of crystal-packing densities and lattice-interaction energies. Efficient close-packing of the ions in the crystalline states is observed, but there was no compelling evidence for specific directional hydrogen-bonding to the hexafluorophosphate anions or the formation of interstitial voids. The close-packing efficiency is supported by the theoretical calculation of ion volumes, crystal lattice energies, and packing densities, which correlated well with experimental data. The crystal density of the salts can be predicted accurately from the summation of free ion volumes and lattice energies calculated. Of even more importance for future work, on these and related salts, the solid-state density of 1,3-dialkylimidazolium hexafluorophosphate salts can be predicted with reasonable accuracy purely on the basis of on ab initio free ion volumes, and this allows prediction of lattice energies without necessarily requiring the crystal structures.

Disposable solid state probe for optical screening of chlorpromazine

We are presenting a simple, low-cost and rapid solid-state optical probe for screening chlorpromazine (CPZ) in aquacultures. The method exploits the colourimetric reaction between CPZ and Fe(III) ion that occurs at a solid/liquid interface, the solid layer consisting of ferric iron entrapped in a layer of plasticized PVC. If solutions containing CPZ are dropped onto such a layer, a colour change occurs from light yellow to dark pink or even light blue, depending on the concentration of CPZ. Visual inspection enables the concentration of CPZ to be estimated. The resulting colouration was also monitored by digital image collection for a more accurate quantification. The three coordinates of the hue, saturation and lightness system were obtained by standard image processing along with mathematical data treatment. The parameters affecting colour were assessed and optimized. Studies were conducted by visible spectrophotometry and digital image acquisition, respectively. The response of the optimized probe towards the concentration of CPZ was tested for several mathematical transformations of the colour coordinates, and a linear relation was found for the sum of hue and luminosity. The limit of detection is 50 μM (corresponding to about 16 μg per mL). The probe enables quick screening for CPZ in real water samples with prior sample treatment.

Banana waste as substrate for a-amylase production by Bacillus subtilis (CBTK 106) under solid-state fermentation

Bacillus subtilis CBTK 106, isolated from banana wastes, produced high titres of a-amylase when banana fruit stalk was used as substrate in a solid-state fermentation system. The e¤ects of initial moisture content, particle size, cooking time and temperature, pH, incubation temperature, additional nutrients, inoculum size and incubation period on the production of a- amylase were characterised. A maximum yield of 5 345 000 U mg~1 min~1 was recorded when pretreated banana fruit stalk (autoclaved at 121 ¡C for 60 min) was used as substrate with 70% initial moisture content, 400 lm particle size, an initial pH of 7.0, a temperature of 35 ¡C, and additional nutrients (ammonium sulphate/sodium nitrate at 1.0%, beef extract/peptone at 0.5%, glucose/sucrose/starch/maltose at 0.1% and potassium chloride/sodium chloride at 1.0%) in the medium, with an inoculum-to-substrate ratio of 10% (v/w) for 24 h. The enzyme yield was 2.65-fold higher with banana fruit stalk medium compared to wheat bran

Production, purification and partial characterization of a novel protease from marine Engyodontium album BTMFS10 under solid state fermentation

Engyodontium album isolated from marine sediment produced protease, which was active at pH 11. Process parameters influencing the production of alkaline protease by marine E. album was optimized. Particle size of <425 mm, 60% initial moisture content and incubation at 25 8C for 120 h were optimal for protease production under solid state fermentation (SSF) using wheat bran. The organism has two optimal pH (5 and 10) for maximal enzyme production. Sucrose as carbon source, ammonium hydrogen carbonate as additional inorganic nitrogen source and amino acid leucine enhanced enzyme production during SSF. The protease was purified and partially characterized. A 16-fold purified enzyme was obtained after ammonium sulphate precipitation and ion-exchange chromatography. Molecular weight of the purified enzyme protein was recorded approximately 38 kDa by SDS-PAGE. The enzyme showed maximum activity at pH 11 and 60 8C. Activity at high temperature and high alkaline pH suggests suitability of the enzyme for its application in detergent industry

Extracellular β-glucosidase Production by a Marine Aspergillus sydowii BTMFS 55 under Solid State Fermentation Using Statistical Experimental Design

A potential fungal strain producing extracellular β-glucosidase enzyme was isolated from sea water and identified as ^ëéÉêJ Öáääìë=ëóÇçïáá BTMFS 55 by a molecular approach based on 28S rDNA sequence homology which showed 93% identity with already reported sequences of ^ëéÉêÖáääìë=ëóÇçïáá in the GenBank. A sequential optimization strategy was used to enhance the production of β-glucosidase under solid state fermentation (SSF) with wheat bran (WB) as the growth medium. The two-level Plackett-Burman (PB) design was implemented to screen medium components that influence β-glucosidase production and among the 11 variables, moisture content, inoculums, and peptone were identified as the most significant factors for β-glucosidase production. The enzyme was purified by (NH4)2SO4 precipitation followed by ion exchange chromatography on DEAE sepharose. The enzyme was a monomeric protein with a molecular weight of ~95 kDa as determined by SDS-PAGE. It was optimally active at pH 5.0 and 50°C. It showed high affinity towards éNPG and enzyme has a hã and sã~ñ of 0.67 mM and 83.3 U/mL, respectively. The enzyme was tolerant to glucose inhibition with a há of 17 mM. Low concentration of alcohols (10%), especially ethanol, could activate the enzyme. A considerable level of ethanol could produce from wheat bran and rice straw after 48 and 24 h, respectively, with the help of p~ÅÅÜ~êçãóÅÉë=ÅÉêÉîáëá~É in presence of cellulase and the purified β-glucosidase of ^ëéÉêÖáääìë=ëóÇçïáá BTMFS 55.

Synthesis, structure and solution chemistry of dioxidovanadium(V) complexes with a family of hydrazone ligands. Evidence of formation of centrosymmetric dimers via H-bonds in the solid state

[(VO)-O-IV(acac) 2] reacts with the methanol solution of tridentate ONO donor hydrazone ligands (H2L1-4, general abbreviation H2L; are derived from the condensation of benzoyl hydrazine with 2-hydroxyacetophenone and its 5-substituted derivatives) in presence of neutral monodentate alkyl amine bases having stronger basicity than pyridine e. g., ethylamine, diethylamine, triethylamine and piperidine (general abbreviation B) to produce BH+[VO2L] (1-16) complexes. Five of these sixteen complexes are structurally characterized revealing that the vanadium is present in the anionic part of the molecule, [VO2L] in a distorted square pyramidal environment. The complexes 5, 6, 15 and 16 containing two H-atoms associated with the amine-N atom in their cationic part (e. g., diethylammonium and piperidinium ion) are involved in H-bonding with a neighboring molecule resulting in the formation of centrosymmetric dimers while the complex 12 (containing only one hydrogen atom in the cationic part) exhibits normal H-bonding. The nature of the H-bonds in each of the four centrosymmetric dimeric complexes is different. These complexes have potential catalytic activity in the aerial oxidation of L-ascorbic acid and are converted into the [VO(L)(hq)] complexes containing VO3+ motif on reaction with equimolar amount of 8-hydroxyquinoline (Hhq) in methanol.

Solid state NMR as a new approach for the structural characterization of rare-earth doped lead lanthanum zirconate titanate laser ceramics

To facilitate the design of laser host materials with optimized emission properties, detailed structural information at the atomic level is essential, regarding the local bonding environment of the active ions (distribution over distinct lattice sites) and their extent of local clustering as well as their population distribution over separate micro- or nanophases. The present study explores the potential of solid state NMR spectroscopy to provide such understanding for rare-earth doped lead lanthanum zirconate titanate (PLZT) ceramics. As the NMR signals of the paramagnetic dopant species cannot be observed directly, two complementary approaches are utilized: (1) direct observation of diamagnetic mimics using Sc-45 NMR and (2) study of the paramagnetic interaction of the constituent host lattice nuclei with the rare-earth dopant, using Pb-207 NMR lineshape analysis. Sc-45 MAS NMR spectra of scandium-doped PLZT samples unambiguously reveal scandium to be six-coordinated, suggesting that this rare-earth ion substitutes in the B site. Static Pb-207 spin echo NMR spectra of a series of Tm-doped PLZT samples reveal a clear influence of paramagnetic rare-earth dopant concentration on the NMR lineshape. In the latter case high-fidelity spectra can be obtained by spin echo mapping under systematic incrementation of the excitation frequency, benefiting from the signal-to-noise enhancement afforded by spin echo train Fourier transforms. Consistent with XRD data, the Pb-207 NMR lineshape analysis suggests that statistical incorporation into the PLZT lattice occurs at dopant levels of up to 1 wt.% Tm3+, while at higher levels the solubility limit is reached. (C) 2008 Elsevier Masson SAS. All rights reserved.

High mobility I− / I3− redox couple in a molecular plastic crystal: A potential new generation of electrolyte for solid-state photoelectrochemical cells

A series of new electrolyte materials based on a molecular plastic crystal doped by different iodide salts together with iodine have been prepared and characterized by thermal analysis, ionic conductivity, electrochemical and solid-state NMR diffusion measurements. In these materials, the plastic crystal phase of succinonitrile acts as a good matrix for the quaternary ammonium based iodides and iodine and appears to act in some cases as a solid-state “solvent” for the binary dopants. The materials were prepared by mixing the components in the molten state with subsequent cooling into the plastic crystalline state. This resulted in waxy-solid electrolytes in the temperature range from − 40 to 60 °C. The combination of structural variation of the cations, and fast redox couple diffusion (comparable with liquid-based electrolytes), as well as a high ionic conductivity of up to 3 × 10^{− 3} S cm^{− 1} at ambient temperature, make these materials very attractive for potential use in solid-state photoelectrochemical cells.

Rapid I−/I3− diffusion in a molecular-plastic-crystal electrolyte for potential application in solid-state photoelectrochemical cells

High current-carrying capacity and rapid, liquidlike diffusion were achieved in a dye-sensitized solar cell (DSSC) based on the plastic-crystalline electrolyte succinonitrile and the I⁻/I₃⁻ redox couple (see diagram). This could lead to the development of true solid-state DSSCs without conventional organic-liquid electrolytes, which can cause problems with long-term device stability.