CpMo(CO)3Cl as a precatalyst for the epoxidation of olefins

The tricarbonyl complex CpMo(CO)₃C1 was found to act as a precatalyst for the reaction of tert-butyl hydroperoxide and olefins to yield the corresponding epoxides and diols. Under the reaction conditions, oxidative decarbonylation leads to the formation of the dioxo complex CpMoO₂Cl. The catalytic recyclability and the effect of temperature on the catalytic results have been examined, and a reaction mechanism proposed, supported by kinetic modelling.     

On the approximation of compact fuzzy sets

This paper suggests an approximation for a compact fuzzy set by a sequence of Lipschitz fuzzy sets. This approximation method involves the construction of Lipschitz fuzzy sets using the sup–min convolution of a compact fuzzy set with a fuzzy zero. Considering a similar procedure, we present the approximation of a trapezoidal type fuzzy interval by a sequence of differentiable fuzzy intervals. We show some important properties of both approximations and we give some numerical examples illustrating the results.     

Multiobjective optimization for the socio-eco-efficient conversion of lignocellulosic biomass to biofuels and bioproducts

Clean Technologies and Environmental Policy - This work focuses on a way to integrate the social, environmental and economic aspects (socio-eco-efficient aspects) together in the decisions...     

Evaluation of the EC8-3 confidence factors for the characterization of concrete strength in existing structures

A probabilistic framework is defined to evaluate the values of the Confidence Factors (CFs) proposed in Eurocode 8 Part 3 (EC8-3) for the characterization of material properties. This evaluation is presented for the concrete compressive strength but its validity for other material properties can also be inferred from the results obtained. The number of material tests and the existence of prior knowledge are the essential aspects for the CF quantification. The probabilistic framework proposed in the first part of the study does not consider the existence of prior knowledge and is based on the concept of confidence intervals. In the second part of the study, the effects of prior knowledge are considered using a Bayesian framework. The combination of testing data obtained from different types of tests is also addressed as an extension of the referred Bayesian approach. Results indicate that the EC8-3 proposed CFs for KL1 and KL2 are adequate, but for KL3 it is suggested that a larger value should be used.     

Potential of roof-integrated solar collectors for preheating air at drying facilities in Northern Thailand

Longan is one of the most widely cropped fruits in Northern Thailand, where a significant amount of the annual harvest is commercially dried and exported as a commodity. Liquefied petroleum gas is generally used as the energy source for heating the drying air, but concern is growing as fuel prices are expected to increase for the foreseeable future. Meanwhile, with the ample solar radiation in Thailand, the roofs of drying facilities could be adapted to serve as solar collectors to preheat the drying air, thus reducing the energy requirement from fossil fuels. In this study, a simulation program for a flat-plate solar air heater was used to estimate the potential to preheat drying air given the conditions of several longan drying facilities. Results showed that solar collectors can replace up to 19.6% of the thermal energy demand during the drying season. Bigger collectors and smaller air channels result in more useful heat, but attention has to be paid to costs and pressure drop, respectively. Annual monetary savings can reach up to THB 56,000 (≈US$ 1800 at US$ 1 = THB 31).     

The Effect of the Argon Carrier Gas in the Multiphoton Dissociation-Ionization of Tetracene

The multiphoton dissociation-ionization of tetracene at 355 nm using 6.5 nanosecond laser pulses, with and without argon as a carrier gas (CG), has been studied and compared. Ion fragments were analyzed in a time-of-flight mass spectrometer and separated according to their mass-to-charge ratio (m/z). The results show that the dynamic of photodissociation at ∼10¹⁰ W cm⁻² intensities is strongly influenced by the CG. The suppression of fragmentation channels primarily those relating to the formation of the CH_m⁺ (m = 2, 4), C₂H₄⁺ and C₅H₄⁺² ions. CH₅⁺ and CH₆⁺ were observed which have not been reported before in photodissociation tetracene experiments.     

Influence of thermal ageing on surface degradation of ethylene‐propylene‐diene elastomer

Evolution of the surface characteristics of EPDM elastomer was studied as a function of thermal ageing at 80°C and 120°C in air for up to 100 days. The components of the surface free energy (SFE) were determined from contact angle measurements of five liquids using acid–base regression and Fowke's theories. SFE increased with ageing duration. For ageing at 80°C, SFE increased exponentially with time and stabilized after 60 days. Ageing at 120°C promoted a steep enhancement of SFE within the first 5 days followed by a slow long‐term linear increase. Rate parameters of the SFE evolution were analyzed using Dakin's kinetic model. Analysis of the surface composition using X‐ray photoemission spectroscopy evidenced an enhancement of the oxygen content with increasing the ageing time. The increase of the polar component of the SFE was attributed to the presence of these oxygen functional groups. This tendency was more pronounced for ageing at 80°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Stimuli-responsive chitosan/poly (<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) semi-interpenetrating polymer networks: effect of pH and temperature on their rheological and swelling properties

The aim of this work was to synthesize semi-interpenetrating polymer networks (semi-IPNs) by free radical polymerization of N-isopropylacrylamide [poly (NIPAAm)], in the presence of chitosan (CHI), and to study the effect of pH and temperature changes on their rheological and swelling properties. The semi-IPNs are thermally stable up to about 400 °C and the presence of CHI increases the thermal degradation rate compared to bare poly (NIPAAm). The prepared systems presents a well-defined porosity and proved to be non-toxic, in vitro, on human embryonic skin fibroblast, thus offering appropriate support for cell proliferation. The semi-IPNs present, at physiological pH, swelling degrees well below those of the pure poly (NIPAAm). Differently, at acidic pH, the CHI macromolecules are protonated and become much more permeable to the diffusion of water giving a swelling degree that approaches that of bare poly (NIPAAm). The viscoelastic moduli of the semi-IPNs increase as a function of pH while the LCST remain unchanged. Moreover, the semi-IPNs viscoelastic moduli increase with the increase of CHI content and, in particular, the difference between the elastic modulus before and after the sol/gel transition is higher for the semi-IPN than for bare poly (NIPAAm) just at about physiological conditions.