Preparation of multi-compositional gas sensing films by combinatorial solution deposition

Various compositions of gas sensing films were prepared by the combinatorial deposition of SnO₂, ZnO, and WO₃ sol solutions and their gas sensing behaviors were investigated. The film composition could be manipulated conveniently via the alternate dropping of different oxide sol solutions. From the correlation between film compositions and gas sensitivities, the selective detection of C₂H₅OH and CH₃COCH₃ in the presence of CO, C₃H₈, H₂, and NO₂ could be attained. In addition, the discrimination between C₂H₅OH and CH₃COCH₃, which is a challenging issue due to their similar chemical nature, becomes possible. This research demonstrates the precise design of the sensor-material composition for the selective gas detection via the combinatorial approach.     

Corrosion protection of iron by polypyrrole coatings electrosynthesised from a surfactant solution

This work is a study of the electropolymerisation of pyrrole onto iron electrodes in the presence of sodium bis(2-ethylhexyl) sulfosuccinate in a wide pH interval. The characterisation of the films was done using electrochemical techniques, SEM/EDX and IR spectroscopy. We show that it is possible to synthesise homogeneous, adherent and very compact films in the pH range between 7 and 12 under potentiodynamic, galvanostatic and potentiostatic conditions without substrate dissolution. The effects of various parameters on electrodeposition were investigated. The new procedure for the electrochemical synthesis of polypyrrole results in improved anticorrosion properties. The inhibition is proposed to be due to the sum of a repulsion of chloride ions because AOT remains entrapped in the polymer matrix and the presence of the iron oxide. Advantages of the use of surfactants in the electropolymerisation solution are discussed.     

Effect of cationic surfactant and inorganic anions on the electrochemical behavior of carbon steel in formation water

Corrosion behavior of carbon steel in formation water associated crude oil from Egyptian western desert was studied at various concentrations of dodecyl dimethyl ammonium chloride (CS) as a cationic surfactant. Polarization curves indicate that CS has a good inhibition efficiency for carbon steel in formation water and behaves as cathodic inhibitor. The inhibition efficiency was found to increase with increase in CS concentration until reaches a maximum constant value corresponding to the critical micelle concentration of CS and decrease with increase in solution temperature. The adsorption of CS follows the kinetic thermodynamic model and Flory-Huggins isotherm. Thermodynamic parameters obtained indicate that that the presence of the CS increases the activation energy. Polarization and Impedance measurements indicate that the addition of KI has a significant synergistic effect with CS and results in increase the inhibition efficiency of CS in formation water.     

Nutrient removal performance of an anaerobic–anoxic–aerobic process as a function of influent C/P ratio

The laboratory scale anaerobic–anoxic–aerobic (A²O) process fed with synthetic brewage wastewater was designed to investigate the effects of changing feed C/P ratio on the performance of biological nutrient removal (BNR) processes. In the experiment, the influent chemical oxygen demand (COD) concentration was kept at approximately 300 mg L^?1 while the total phosphorus concentration was varied to obtain the desired C/P ratio. Results showed that when the C/P ratio was lower than 32, phosphorus removal efficiency increased as C/P ratio increased linearly, while when the C/P ratio was higher than 32, the P removal efficiency was maintained at 90–98%, and effluent P concentration was lower than 0.5 mg L^?1. However, regardless of the C/P ratio, excellent COD removal (90% or higher) and good total nitrogen removal (75–84%) were maintained throughout the experiments. It was also found that very good linear correlation was obtained between COD uptake per unit P released in the anaerobic zone and C/P ratio. In addition, the P content in the wasted activated sludge increased with the decrease in the C/P ratio. Based on the results, it was recommended that the wastewater C/P ratio and its effects be incorporated into BNR design and operational procedures, appropriate C/P ratios were used to achieve the effluent treatment goals. Copyright © 2005 Society of Chemical Industry     

Pressure infiltration of boron nitride preforms with molten aluminum

The infiltration of compacted cubic BN (cBN) with molten aluminum has been investigated as a potential route for a cheap and easy method of manufacturing cBN/metal composites. CBN compacts have been infiltrated with molten Al at a temperature between 670 and 800 °C and pressure of 15 MPa in vacuum. At these temperatures no pronounced interactions between hexagonal and cubic BN with Al was observed, allowing the complete infiltration of cBN with 12 μm mean grain size. After infiltration at 800 °C, the temperature was increased without pressure to convert aluminum into borides and AlN. The hardness of the resulting materials depends on the content of hexagonal, cubic BN and the rate of conversion of Al into borides and AlN. The infiltration height of less than 1 mm obtained from infiltrating the 3 μm cBN powder green compacts gave a hardness of 22.0 ± 0.6 GPa after heat treatment.     

Gildes model studies of aqueous chemistry. III. Initial SO2-induced atmospheric corrosion of copper

The GILDES computer model, incorporating Stumm's concept of proton- and ligand-promoted dissolution, has been used to simulate the exposure of copper at room temperature to 210 ppb sulfur dioxide and 80% relative humidity. The agreement is good between the calculations and laboratory exposures performed under these exposure conditions. Surface reactions are relatively more important at lower relative humidities and the dominant corrosion products formed are solid state Cu₂SO₃, CuSO₃ and Cu₂U. Free-radical redox processes are important participants and control the relative distribution of Cu(I)- and Cu(H)-containing corrosion products.     

COIL中BHP浓度对发生O_2(~1△)的影响

本文实验研究了BHP的浓度对产生O2（1△）的影响。实验结果表明：当BHP浓度大于3.5M时，Cl2利用率以及O2（1△）的产率将不依赖于BHP浓度的变化而变化，同时，实验结果表明，使用低浓度的BHP对COIL的操作是可行的。     

Evolution of BET internal surface area in glassy carbon powder during thermal oxidation

It is demonstrated that glassy carbon powder can be thermochemically activated. During activation, a film with open pores is created on the glassy carbon particles. This film has a large internal surface area, which is accessible to liquids and gases. A simple model for the evolution of the internal surface area in glassy carbon powder during thermochemical gas-phase oxidation is also presented and compared with experimental data. Experimental results are in qualitative agreement with the model. We found that a sharp particle size distribution is desirable with regard to potential technical applications.     

Ecophysiology of ochratoxigenic Aspergillus ochraceus and Penicillium verrucosum isolates. Predictive models for fungal spoilage prevention - a review

Ochratoxin A (OTA) is a secondary metabolite produced by several species of Aspergillus and Penicillium; among them Aspergillus ochraceus and Penicillium verrucosum are two ochratoxigenic species capable of growing in different climates and thus contamination of food crops with OTA can occur worldwide. OTA can be found in a wide range of foods such as cereals, coffee, cocoa, spices, beer, wine, dried vine fruit, grapes and meat products. OTA is toxic to animals, it presents neurotoxic, immunotoxic and nephrotoxic effects. It has been implicated in a human kidney disorder known as Balkan Endemic Nephropathy. This review focuses on the ecophysiology of ochratoxin-producing Aspergillus ochraceus and Penicillium verrucosum, the effect of environmental factors on their germination, mycelial growth, and OTA production. Knowledge of environmental conditions required for sucessive stages of fungal development represent the first step towards preventing mycotoxin formation. Predictive models for different stages of fungal development are presented, which allow prediction of the time before spoilage as a function of the abiotic factors. Finally, the implications of these studies in management of barley, coffee and grapes are described. This can help to identify the critical control points in their production, storage and distribution processes.