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Oxygen plasma functionalized multiwall carbon nanotubes and iron oxide decorated multiwall carbon nanotubes are studied for detecting volatile organic compounds (VOCs) at room temperature. Alumina substrates with interdigitated gold electrodes are employed as transducers and the air-brushing method is used to coat them with a thin film of the differently treated carbon nanotube samples. The electrical characterization of the sensors in the presence of benzene, toluene, acetone, methanol and ethanol vapors is carried out. The different treatments allow for tuning the response of carbon nanotubes and it is found that combining the responses of two sensors (i.e., one decorated with iron oxide and the other treated in an oxygen plasma) enables discriminating the aromatic hydrocarbons from the other VOCs tested. Additionally, discriminating benzene from toluene also appears to be possible. Sensors as the ones presented here, which are operated at room temperature, may led to a new generation of affordable, mass produced portable/wearable detectors with important applications in the selective detection of benzene. [ABSTRACT FROM AUTHOR]

Abstract: The binary liquid mixture of triethylamine+water (TEA–W) has a lower consolute point at a critical composition of 32.27 mass % triethylamine. Starting at a temperature within the one-phase region, the electrical conductivity of a sample of this mixture with addition of (K+, Cl−) ions was measured and found to be accurately described by the Vogel–Fulcher–Tammann (VFT) law. Before that, for the pure system, in a temperature range ΔT = T c − T <2°C where T c is the critical temperature, the electrical conductivity (σ) exhibits a monotonous deviation from the VFT behaviour. This anomaly is finite at T c. The asymptotic behaviour of the electrical conductivity anomaly is described by a power law t 1−α, where t is the reduced temperature and α is the critical exponent of the specific heat anomaly at constant pressure. For the electrolyte mixtures, by combining the viscosity and the electrical conductivity data, the value of the computed Walden product has been determined and the salt dissociation degrees as well as the Debye screening length have been estimated. [Copyright &y& Elsevier]

Abstract: Composition of components by means of multi-party synchronizations and priorities allows specifying properties of systems in a very abstract manner, and are meaningful for many application domains. Such specifications are generally easier to verify than the more concrete ones based on message passing. Synchronizations may introduce deadlocks, whereas priorities do not. In this paper, we propose two algorithms: one which given a specification Sys constructs — if necessary and if possible — a set of priority rules enforcing deadlock freedom. A second algorithm builds a distributed implementation of such a prioritized specification. This second algorithm is presently restricted to binary synchronizations but it differs from comparable algorithms such as -core (1) by the fact that it handles specifications with (global) priorities. We have implemented this algorithm and compared its efficiency with -core in the priorityless case. [Copyright &y& Elsevier]

Abstract: Densities ρ and viscosities η, for the binary mixture triethylamine–water have been measured over the entire range of mole fractions at different temperatures, both near and far away from the critical temperature T c (0.076K≤(T − T c)≤8.276K). By calculating the corresponding activation parameters ΔH* and ΔS*, it has been shown that a possible connection may be presented between the evolution of these parameters and the critical region. Furthermore, in the one-phase region just below T c of the critical (TEA–W) binary fluid, the viscosity measurements yield an enhancement as expected for Ising criticality with a crossover to regular behaviour. The regular background is obtained by interpolation from the measurements at non-critical concentrations. Shear viscosity data are consistent with a power law divergence η = η 0(Qξ 0) z t −y F predicted by the mode-coupling and the dynamic renormalization group theories. Different equations are used in order to determine the critical exponent y, the obtained values are in good agreement with the renormalization group-predicted value. The best fit gives y = νz =0.0391±0.0002 (i.e., z =0.0679). Moreover, the resulting value for the wave number Q =1.0152±0.0016nm−1 is in the region found for many other systems. [Copyright &y& Elsevier]

Abstract: Recently, oxide semiconductor material used as transducer has been the central topic of many studies for gas sensor. In this paper we investigated the characteristic of a thick film of tin dioxide (SnO2) film for chemical vapor sensor. It has been prepared by screen-printing technology and deposited on alumina substrate provided with two gold electrodes. The morphology, the molecular composition and the electrical properties of this material have been characterized respectively by Atomic Force Spectroscopy (AFM), Fourier Transformed Infrared Spectroscopy (FTIR) and Impedance Spectroscopy (IS). The electrical properties showed a resistive behaviour of this material less than 300 °C which is the operating temperature of the sensor. The developed sensor can identify the nature of the detected gas, oxidizing or reducing. [Copyright &y& Elsevier]