Lattice energy estimation for inorganic ionic crystals

An empirical method based on chemical bond theory for the estimation of the lattice energy for ionic crystals has been proposed. The lattice energy contributions have been partitioned into bond dependent terms. For an individual bond, the lattice energy contribution made by it has been separated into ionic and covalent parts. Our calculated values of lattice energies agree well with available experimental and theoretical values for diverse ionic crystals. This method, which requires detailed crystallographic information and elaborate computation, might be extended and possibly yield further insights with respect to bond properties of materials.

Confining conducting polyaniline in a stable inorganic network

Water soluble conducting polyaniline with electrical conductivity of 10(-1)-10(-2) S/cm was prepared employing dopant induced water solubility technology. The water resistance of the conducting film was significantly improved employing,sol-gel hybrids method, especially when the conductive polyaniline loading was below 30 wt%. The reason for the improvement is that the conducting polyaniline chains are confined in a stable inorganic network.

Photochromic behavior and luminescent properties of novel hybrid organic-inorganic film doped with Preyssler's heteropoly acid H-12[EuP5W30O110] and polyvinylpyrrolidone

A novel hybrid photochromic composite film composed of Preyssler's heteropoly acid H-12[EuP5W30O110] (EuP5W30) and polyvinylpyrrolidone (PVP) was prepared by dip-coating method. Atomic force microscopy (AFM) was used to investigate the surface topography. The change of characteristic peak in the infrared spectra (IR) was investigated. The TG curve showed three steps of weight loss and approximately revealed the composition of the hybrid film. Ultraviolet-visible adsorption spectra (UV-VIS) and electron resonance spectrum (ESR) were used to investigate the photochromic behavior and mechanism of hybrid film. The photoluminescent behavior of the film at room temperature was investigated to show the characteristic Eu3+ emission pattern of D-5(o)-F-7(J). The occurrence of photoluminescent activity confirms the potential for creating luminescent thin film with polyoxometalates (POMs).

Conformation change of horseradish peroxidase in lipid membrane

The electrochemical behavior of horseradish peroxidase (HRP) in the dimyristoyl phosphatidylcholine (DMPC) bilayer on the glassy carbon (GC) electrode was studied by cyclic voltammetry. The direct electron transfer of HRP was observed in the DMPC bilayer. Only a small cathodic peak was observed for HRP on the bare GC electrode. The electron transfer of HRP in the DMPC membrane is facilitated by DMPC membrane. UV-Vis and circular dichroism (CD) spectroscopy were used to study the interaction between HRP and DMPC membrane. On binding to the DMPC membrane the secondary structure of HRP remains unchanged while there is a substantial change in the conformation of the heme active site. Tapping mode atomic force microscopy (AFM) was first applied for the investigation on the structure of HRP adsorbed on supported phospholipid bilayer on the mica and on the bare mica. HRP molecules adsorb and aggregate on the mica without DMPC bilayer. The aggregation indicates an attractive interaction among the adsorbed molecules. The molecules are randomly distributed in the DMPC bilayer. The adsorption of HRP in the DMPC bilayer changes drastically the domains and defects in the DMPC bilayer due to a strong interaction between HRP and DMPC films.

Electrochemical H2S sensor with H2SO4 pre-treated Nafion membrane as solid polymer electrolyte

It is reported for the first time that the performance of the electrochemical H2S sensor with the Nation membrane pre-treated with the concentrated H2SO4 as the solid electrolyte is much more stable than that for the sensor with the Nation membrane without H2SO4 pretreatment. The sensitivity of the sensor is about 2.92 muA/ppm. The response time of the sensor is about 9 s. The detection limit is about 0.1 ppm. Therefore, this kind of the electrochemical H2S gas sensor may be desirable for the practical application.

Hybrid organic-inorganic compounds doped with terbium carboxyl complexes produced in situ via a sol-gel approach

In situ synthesis of terbium carboxyl complexes in an organic-inorganic hybrid matrix by a sol-gel process has been proposed. The formation of terbium carboxyl complexes in the hybrid matrix is confirmed by the luminescence spectra and IR spectra. It is observed that the location at the amino group in aminobenzoic acid has a large effect on the luminescence properties and lifetimes. Furthermore, the emission intensity decreases with increasing temperature.

Study on transfer and interfacial kinetics of neodymium and samarium in membrane based extraction

Extraction and interfacial kinetics of Nd3+ and Sm3+ with HER/EHP-kerosene in a hollow fiber membrane extractor were studied. The results show that the extraction reactions in the hollow fiber membrane extractor are the same as those in the liquid-liquid extraction, which can be expressed as a quasi-first-order reaction. The effect of acidity in aqueous phase, concentrations of extractant, Nd3+ and Sm3+ on extraction rate were discussed and the corresponding reaction series were obtained. The reaction equations, reaction rate constants and the separation constant were obtained.

An unusual organic-inorganic chain-like hybrid complex [(CuCl)(2)(o-phen)](infinity) (o-phen=o-phenanthroline)

A novel organic-inorganic hybrid complex [(CuCl)(2) (o-phen)](infinity) 1 (o-phen = o-phenanthroline) has been hydrothermally synthesized and structurally characterized by elemental analyses, XPS spectrum, TG analysis, and single-crystal X-ray diffraction. Compound I crystallizes in the monoclinic system, space group P2(1)/n, a = 3.7285(7) Angstrom, b = 19.603(4) Angstrom, c = 16.757(3) Angstrom, beta = 95.83(3)degrees, V = 1218.4(4) Angstrom(3), Z = 4, lambda(MoKalpha) = 0.71073 Angstrom (R(F) = 0.0643 for 2559 reflections). Data were collected on an R-axis RAPID diffractometer at 293 K in the range of 1.60 < θ < 27.48degrees. The title compound exhibits a one-dimensional chain-like scaffolding constructed by the unusual [Cu3Cl3] hexagon motifs by, sharing opposite edges. Only Cu(1) sites of the [Cu3Cl3] hexagon are coordinated with N donors of o-phen groups. Furthermore, the three-dimensional supermolecular architecture is formed by C-H...Cl hydrogen bonds between o-phen groups and CuCl chains.

Interaction of low-molecular-weight chitosan with mimic membrane studied by electrochemical methods and surface plasmon resonance

Chitosan has shown its potential as a non-viral gene carrier and an adsorption enhancer for subsequent drug delivery to cells. These results showed that chitosan acted as a membrane perturbant. However, there is currently a lack of direct experimental evidence of this membrane perturbance effect, especially for chitosans with low molecular weight (LMW). In this report, the interaction between a lipid (didodecyl dimethylammonium bromide; DDAB) bilayer and chitosan with molecular weight (MW) of 4200 Da was studied with cyclic voltammetry (CV), electrochemical impedance spectroscopy and surface plasmon resonance (SPR). A lipid bilayer was formed by-fusion of oppositely charged lipid vesicles on a mercaptopropionic acid (MPA)-modified gold surface to mimic a cell membrane. The results showed that the LMW chitosan could disrupt the lipid bilayer, and the effect seemed,to be in a concentration-dependent manner.

Effect of properties of active carbon supports on performance of Pt/C catalysts in polymer electrolyte membrane fuel cell

The Pt/C catalysts were prepared with pine active carbon and Vulcan XC-72 active carbon as the supports. The performances of the Pt/C catalysts in polymer electrolyte membrane fuel cell were compared. The result indicates that the performance of Pt/Vulcan XC-72 is better than that of Pt/pine. The physical and chemical properties of the two active carbons were measured using several analysis techniques. It was found that the pore size, specific conductivity and the surface function group significantly influence the performance of the electrocatalyst.

Study of the interaction between lanthanide ions and a supported bilayer lipid membrane by cyclic voltammetry and ac impedance

The interaction of lanthanide ions with a supported bilayer lipid (1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine) membrane (sBLM) was investigated by cyclic voltammetry and ac impedance spectroscopy in this paper, Lanthanide can affect the conformation of the supported bilayer lipid membrane and cause pore formation. Through the pores, Fe(CN)(6)(3) (4) can reach the electrode surface and show its redox behaviour. Furthermore the redox currents or Fe(CN)(6)(3) (4) increased with increasing concentration of lanthanides and leveled off at 1.2 muM for Eu3+. The interaction ability of three lanthanides with sBLM follows the sequence: Eu3+ > Tb3+ > La3+.

Photoluminescence of organic-inorganic hybrid SiO2 xerogels

Organic-inorganic hybrid SiO2 xerogels were prepared by the sol-gel method under various preparation conditions and compositions by using tetraethoxysilane (TEOS), (3-aminopropyl) triethoxysilane (A-PS), (3-glycidoxypropyl) trimethoxysilane (GPS), organic acid (CH3COOH) and inorganic acids (HCl, HNO3, H2SO4) as the main precursors. Luminescence and FT-IR spectra were used to characterize the resulted hybrid SiO2 xerogels. The result of FT-IR spectrum shows that the xerogels are composed of non-crystalline -Si-O-Si- networks containing some organic groups such as -NH, -CH and -OH. Under the excitation of 365 nm, all the hybrid xerogels exhibit strong luminescence in the blue region, but the emission intensity and position depend on the starting precursor compositions to a large extent. Suitable amount of polyethylene glycol (PEG500 and PEG10000) in the hybrid xerogels can enhance the emission intensity. Additionally, the emission intensity of the hybrid xerogels increases with heat treatment temperature in the range of ambient to 200degreesC, and vacuum condition is also able to enhance the emission intensity.

Formation of a supported hybrid bilayer membrane on gold: A sterically enhanced hydrophobic effect

Adsorption of a monolayer of didecanoyl-L-alpha-phosphatidylcholine (DDPC) from dispersions of small unilamellar vesicles onto hydrophobic surfaces was investigated by mean of cyclic voltammetry and impedance spectroscopy. The hydrophobic surfaces were self-assembled monolayers of 2-mereapto-3-n-octylthiophene (MOT) on gold. One characteristic of the MOT monolayer is its permeability to organic molecules in aqueous solution, thus providing a more energetically favorable hydrophobic surface for the addition of phospholipid vesicles. The kinetics of the lipid monolayer formation were followed by measuring the time-dependent interfacial capacitance. Unusual values of thickness and capacitance of the MOT/ DDPC bilayers were observed. An interdigitating conformation of the bilayer structure was proposed to interpret the experimental results, The horseradish peroxidase reconstituted into the bilayer demonstrated the expected protein activity, showing practical use in research and in biosensor application.

Determination of the interfacial acidity of the functional alkanethiols self-assembly membrane by capacitance measurement

The acid-base equilibrium of self-assembly monolayer(SAM) of mercaptopropionic acid on gold electrode was studied by capacitance titration. The change of capacitance was due to protonation and deprotonation of the modified electrode surface. This method can be used to measure pH value in solution and capacitance of solid/liquid on SAMs surface synchronously. The shift of pK(a) was observed during the experiment as previous reports. The factors that affect the capacitance measurement were discussed in detail.

Characterization of organic-inorganic multilayer films by cyclic voltammetry, UV-Vis spectrometry, X-ray photoelectron spectroscopy, small-angle X-ray diffraction and electrochemical impedance spectroscopy

We have employed several techniques, including cyclic voltammetry, UV-Vis spectrometry, small-angle X-ray diffraction, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy, to characterize the formation processes and interfacial features of ultrathin multilayer films of silicotungstate and a cationic redox polymer on cysteamine-coated Au electrodes self-assembled monolayers. All of these techniques confirm that the multilayer films are built up stepwise as well as uniformly in a layer-by-layer fashion. In particular, the electrochemical impedance spectroscopy is successfully used to monitor the multilayer deposition processes. It has been proved that the electrochemical impedance spectroscopy is a very useful technique in characterization of multilayer films because it provides valuable information about the interfacial impedance features.