Atmospheric Pressure Chemical Vapour Deposition of thin Films of Nb2O5 on Glass

A novel route involving atmospheric pressure chemical vapour deposition (APCVD) is reported for coating Nb2O5 onto glass substrates via the reaction of NbCl5 and ethyl acetate at 400-660degreesC. Raman spectroscopy is shown to be a simple diagnostic tool for the analysis of these thin films. The contact angle of water on Nb2O5-coated glass drops on UV irradiation from 60degrees to 5-20degrees. XPS Analysis showed that the Nb:O ratio of the film was 1:2.5. Glancing angle X-ray diffraction showed that all films were crystalline, with only a single phase being observed; this has some preferred orientation in the (201) plane of Nb2O5. The niobium(V) oxide materials show minimal photocatalytic ability to degrade organic material.

Novel TiO2 CVD films for semiconductor photocatalysis

A novel CVD film of titanium(IV) oxide has been prepared on glass, via the reaction of titanium(IV) chloride and ethyl acetate, using a CVD technique. The film is clear, very robust mechanically and comprised of a thin (24 nm) layer of nanocrystalline anatase titania that absorbs light of lambda

Effect of plasticizer-polymer compatibility on the response characteristics of optical thin CO2 and O-2 sensing films

A homologous family of dialkyl phthalates has been used to investigate the effect of plasticizer/polymer compatibility on the response characteristics of transparent, plastic, thin optical gas sensing films for CO2 and oxygen. Plasticizer/polymer compatibilities were determined through the value of the difference in solubility parameter, i.e. Delta delta, for the plasticizer and polymer with a Delta delta value of zero indicating high compatibility. A strong correlation was found between plasticizer/polymer compatibility and sensitivity in phenol red/ethyl cellulose CO2-sensitive films and this relationship extended to CO2-sensitive films based on other polymers such as polystyrene and poly(methyl methacrylate). It extended also to optical O-2-sensitive films implying that the relationship is general for thin-film optical sensors. Other results from the CO2-sensitive films in different polymers indicated that the film sensitivity is largely independent of the polymer matrix regardless of its inherent gas permeability, when a sufficient quantity of compatible plasticizer is present. (C) 1998 Elsevier Science B.V.

Thermodynamic Properties of Mixtures Containing Ionic Liquids. 4. LLE of Binary Mixtures of [C2MIM][NTf2] with Propan-1-ol, Butan-1-ol, and Pentan-1-ol and [C4MIM][NTf2] with Cyclohexanol and 1,2-Hexanediol Including Studies of the Influence of Small Amounts of Water

Experimental data are presented for liquid-liquid equilibria of mixtures of the room-temperature ionic liquid 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([C2MIM][NTf2]) with the three alcohols propan-1-ol, butan-1-ol, and pentan-1-ol and for the 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl) imide ([C4MIM][NTf2]) with cyclohexanol and 1,2-hexanediol in the temperature range of 275 K to 345 K at ambient pressure. The synthetic method has been used. Cloud points at a given composition were observed by varying the temperature and using light scattering to detect the phase splitting. In addition, the influence of small amounts of water on the demixing temperatures of binary mixtures of [C2MIM][NTf2] and propan-1-ol, butan-1-ol, and pentan-1-ol was investigated.

Oligomerisation of linear 1-olefins using a chlorogallate(III) ionic liquid

A Lewis acidic chlorogallate(III) ionic liquid, 1-ethyl-3-methylimidazolium hepta-chlorodigallate(III), [C(2)mim][Ga2Cl7], was successfully used to oligomerise 1-pentene. The influence of temperature, time, catalyst concentration, and stirring rate on conversion and product distribution was modelled using a design of experiment (DoE) approach (chemometrics). The process was optimised for lubricant base oils production; the C20-C50 fraction (where Cn indicates the number of carbons in the oligomer) was maximised, while the heavier oligomer fraction (>C50) was minimised.

Detection of 3-amino-2-oxazolidinone (AOZ), a tissue-bound metabolite of the nitrofuran furazolidone, in prawn tissue by enzyme immunoassay

Furazolidone, a nitrofuran antibiotic, is banned from use in food animal production within the European Union. Increasingly, compliance with this ban is monitored by use of analytical methods to detect a stable tissue-bound metabolite, 3-amino-2-oxazolidinone (AOZ). Widespread use of furazolidone in poultry and prawns imported into Europe highlighted the urgent need for development of nitrofuran immunoassay screening tests. The first enzyme-linked immunoabsorbant assay for detection of AOZ residues in prawns (shrimps) is now described. Prawn samples were derivatized with o-nitrobenzaldehyde, extracted into ethyl acetate, washed with hexane and applied to a competitive enzyme immunoassay based on a rabbit polyclonal antiserum. Assay limit of detection (LOD) (mean+3 s) calculated from the analysis of 20 known negative cold and warm water prawn samples was 0.1 mug kg(-1). Intra- and interassay relative standard deviations were determined as 18.8 and 38.2%, respectively, using a negative prawn fortified at 0.7 mug kg(-1). The detection capability (CCbeta), defined as the concentration of AOZ at which 20 different fortified samples yielded results above the LOD, was achieved at fortification between 0.4 and 0.7 mug kg(-1). Incurred prawn samples (n=8) confirmed by liquid chromatography coupled with tandem mass spectrometry detection to contain AOZ concentrations between 0.4 and 12.7 mug kg(-1) were all screened positive by this enzyme-linked immunoabsorbant assay. Further data are presented and discussed with regard to calculating assay LOD based on accepting a 5% false-positive rate with representative negative prawn samples. Such an acceptance improves the sensitivity of an ELISA and in this case permitted an LOD of 0.05 mug kg(-1) and a CCbeta of below 0.4 mug kg(-1).

Determination of thyreostat residues from bovine matrices using high-performance liquid chromatography

High-performance liquid chromatography (HPLC) methodologies were evaluated for the detection and quantification of thyreostatic drug residues in cattle serum and thyroid tissue. The paper details a protocol, using a simple ethyl acetate extraction for the determination of thiouracil, tapazole, methyl thiouracil, propyl thiouracil and phenyl thiouracil in thyroid tissue. Using two sequential HPLC injections, and quantitative analysis, in two steps, all five thyreostats were detectable at concentrations greater than 2.45-4.52 ng/g. Modifications to a published method for detection of thyreostatic residues in serum involving the addition of mercaptoethanol and a freezing step are described. The modifications improved sensitivity and allowed detection of the five thyreostats at levels greater than 16.98-35.25 ng/ml. Young bulls were treated with thyreostats to demonstrate the validity of the methodologies described. Administered thyreostats were not absorbed equally by the test animals and the compounds were not all detected in the serum samples removed at 7 days following drug withdrawal. These experiments indicate the necessity to be able to detect thyreostat residues in a variety of matrices. (C) 1998 Elsevier Science B.V. All rights reserved.

Rate acceleration of the Baylis-Hillman reaction in polar solvents (water and formamide). Dominant role of hydrogen bonding, not hydrophobic effects, is implicated

A substantial acceleration of the Baylis-Hillman reaction between cyclohexenone and benzaldehyde has been observed when the reaction is conducted in water. Several different amine catalysts were tested, and as with reactions conducted in the absence of solvent, 3-hydroxyquinuclidine was found to be the optimum catalyst in terms of rate. The reaction has been extended to other aldehyde electrophiles including pivaldehyde. Attempts to extend this work to acrylates was only partially successful as rapid hydrolysis of methyl and ethyl acrylates occurred under the base-catalyzed and water-promoted conditions. However, tert-butyl acrylates were sufficiently stable to couple with relatively reactive electrophiles. Further studies on the use of polar solvents revealed that formamide also provided significant acceleration and the use of 5 equiv of formamide (optimum amount) gave faster rates than reactions conducted in water. Using formamide, further acceleration was achieved in the presence of Yb(OTf)(3) (5 mol %). The scope of the new conditions was tested with a range of Michael acceptors and benzaldehyde and with a range of electrophiles and ethyl acrylate. The origin of the rate acceleration is discussed.

INFLUENCE OF ULTRASOUND ON THE PERCUTANEOUS-ABSORPTION OF NICOTINATE ESTERS

The influence of ultrasound on the percutaneous absorption of three nicotinate esters was investigated in 10 healthy volunteers in a double-blind placebo controlled crossover clinical trial. Using a specially designed experimental protocol, the effect of continuous output ultrasound (at frequency 3.0 MHz and intensity 1.0 W/cm2 for 5 min) on the percutaneous absorption of methyl, ethyl, and hexyl nicotinates, from gel bases, was investigated. A placebo control, involving massage with each of the gels, without ultrasound for 5 min, was also incorporated. The pharmacodynamic parameter of vasodilation caused by the nicotinates was used to monitor the percutaneous absorption of the drugs. Laser Doppler velocimetry, a noninvasive optical technique, was used to measure vasodilation of the cutaneous vessels within the treatment site. Ultrasound treatment led to enhanced vasodilator response to the nicotinates, therefore indicating an enhancement of their percutaneous absorption. These agents may prove to be useful compounds in examination of the mechanism of action of phonophoresis.

Low pressure carbon dioxide solubility in pure electrolyte solvents for lithium-ion batteries as a function of temperature. Measurement and prediction

Experimental values for the carbon dioxide solubility in eight pure electrolyte solvents for lithium ion batteries – such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ?-butyrolactone (?BL), ethyl acetate (EA) and methyl propionate (MP) – are reported as a function of temperature from (283 to 353) K and atmospheric pressure. Based on experimental solubility data, the Henry’s law constant of the carbon dioxide in these solvents was then deduced and compared with reported values from the literature, as well as with those predicted by using COSMO-RS methodology within COSMOthermX software and those calculated by the Peng–Robinson equation of state implemented into Aspen plus. From this work, it appears that the CO2 solubility is higher in linear carbonates (such as DMC, EMC, DEC) than in cyclic ones (EC, PC, ?BL). Furthermore, the highest CO2 solubility was obtained in MP and EA solvents, which are comparable to the solubility values reported in classical ionicliquids. The precision and accuracy of the experimental values, considered as the per cent of the relative average absolute deviations of the Henry’s law constants from appropriate smoothing equations and from literature values, are close to (1% and 15%), respectively. From the variation of the Henry’s law constants with temperature, the partial molar thermodynamic functions of dissolution such as the standard Gibbs free energy, the enthalpy, and the entropy are calculated, as well as the mixing enthalpy of the solvent with CO2 in its hypothetical liquid state.

Density and viscosity of several pure and water-saturated ionic liquids

Densities and viscosities were measured as a function of temperature for six ionic liquids (1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazolium ethylsulfate and butyltrimethylammonium bis(trifluoromethylsulfonyl)imide. The density and the viscosity were obtained using a vibrating tube densimeter from Anton Paar and a rheometer from Rheometrics Scientific at temperatures up to 393 K and 388 K with an accuracy of 10-3 g cm-3 and 1%, respectively. The effect of the presence of water on the measured values was also examined by studying both dried and water-saturated samples. A qualitative analysis of the evolution of density and viscosity with cation and anion chemical structures was performed. © The Royal Society of Chemistry 2006.

Influence of the cation on the solubility of CO2 and H 2 in ionic liquids based on the bis(trifluoromethylsulfonyl)imide anion

Experimental values for the solubility of carbon dioxide and hydrogen in three room temperature ionic liquids based on the same anion- (bistrifluoromethylsulfonyl)imide [Ntf2]-and three different cations-1-butyl-3-methylimidazolium, [C4mim], 1-ethyl-3- methylimidazolium, [C2mim] and trimethyl-butylammonium, [N 4111]-are reported between 283 and 343 K and close to atmospheric pressure. Carbon dioxide, with a mole-fraction solubility of the order of 10-2, is two orders of magnitude more soluble than hydrogen. The solubility of CO2 is very similar in the three ionic liquids although slightly lower in the presence of the [C2mim] cation. In the case of H2, noticeable differences were observed with larger mole fraction solubilities in the presence of [N4111] followed by [C 4mim]. All of the mole-fraction solubilities decrease with increasing temperature. From the variation of Henry's law constants with temperature, the thermodynamic functions of solvation were calculated. The precision of the experimental data, considered as the average absolute deviation of the Henry's law constants from appropriate smoothing equations, is always better than ±1%. © Springer Science+Business Media, LLC 2007.

Solubility of carbon dioxide and ethane in three ionic liquids based on the bis{(trifluoromethyl)sulfonyl}imide anion

The objective of this work was to study the influence of changing the cation of the ionic liquid (IL) on gas solubility. For this purpose, the low-pressure solubility of carbon dioxide and of ethane in three ILs based on the bis{(trifluoromethyl)sulfonyl}imide anion ([NTf2](-)) was determined experimentally. Solubility data is reported for 1-ethyl-3-methylimidazolium ([C(1)C(2)Im](+)), 1-butyl-1-methylpyrrolidinium ([C(1)C(4)pyrr](+)) and propylcholinium ([N1132-OH](+)) bis{(trifluoromethyl)sulfonyl}imide ILs between 300 and 345 K. These data are precise to within +/- 1% and accurate to within +/- 5%. In these ILs, carbon dioxide (mole fraction solubility between 1 and 3 x 10(-2), molarity between 0.03 and 0.1 mol L-1) is one order of magnitude more soluble than ethane. The effect of changing the cation is small but significant. Changing the cation has a similar effect on both gases even if the differences are more pronounced in the case of ethane with the order of solubility [C(1)C(4)pyrr][NTf2] > [C(1)C(2)Im][NTf2] > [N1132-OH][NTf2]. For all the systems, the solubility decreases with temperature corresponding to exothermic processes of solvation and negative enthalpies and entropies of solvation were calculated. The properties of solvation of the two gases in [C(1)C(4)pyrr][NTf2] do not vary significantly with temperature while important variations are depicted for both gases in [C(1)C(2)Im][NTf2]. (c) 2007 Elsevier B.V. All rights reserved.

High-pressure volumetric properties of imidazolium-based ionic liquids: Effect of the anion

The densities of five imidazolium-based ionic liquids (ILs) (1-butyl-3-methylimidazolium tetrafluoroborate, [CiC4-Im][BF 4]; 1-butyl-3-methylimidazolium hexafluorophosphate, [CiC 4Im][PF6]; 1-butyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [C1C4Im][Tf 2N]; 1-ethyl-3-methylimidazoliumbis{(trifluoromethyl)sulfonyl}-imide, [C1C2Im][Tf2N]; l-ethyl-3-methylimidazolium ethylsulfate, [C1C2Im][EtSO4]) were measured as a function of temperature from (293 to 415) K and over an extended pressure range from (0.1 to 40) MPa using a vibratingtube densimeter. Knowledge of the variation of the density with temperature and pressure allows access to the mechanical coefficients: thermal expansion coefficient and isothermal compressibility. The effects of the anion and of the length of the alkyl chain on the imidazolium ring on the volumetric properties were particularly examined. The mechanical coefficients were compared with those of common organic solvents, water and liquid NaCl. Finally, a prediction model, based on an "ideal" volumetric behavior of the ILs, is proposed to allow calculation of the molar volume of imidazolium-based ionic liquids as a function of temperature. ©2007 American Chemical Society.

Thermophysical properties, low pressure solubilities and thermodynamics of solvation of carbon dioxide and hydrogen in two ionic liquids based on the alkylsulfate anion

Densities and viscosities of the ionic liquid 1-butyl-3-methylimidazolium octylsulfate, [C4C1Im][C8SO4] were measured as a function of temperature between 313 K and 395 K. Solubilities of hydrogen and carbon dioxide were determined, between 283 K and 343 K, and at pressures close to atmospheric in [C4C1Im][C 8SO4] and in another ionic liquid based on the alkylsulfate anion-1-ethyl-3-methylimidazolium ethylsulfate, [C 2C1Im][C2SO4]. Density and viscosity were measured using a vibrating tube densimeter from Anton Paar and a rheometer from Rheometrics Scientific with accuracies of 10-3 g cm -3 and 1%, respectively. Solubilities were obtained using an isochoric saturation technique and, from the variation of solubility with temperature, the partial molar thermodynamic functions of solvation, such as the standard Gibbs energy, the enthalpy, and the entropy, are calculated. The precision of the experimental data, considered as the average absolute deviation of the Henry's law constants from appropriate smoothing equations, is better than ±1%. © The Royal Society of Chemistry.