Reduction and catalytic behaviour of heterobimetallic copper–lanthanide oxides

The reduction of the heterobimetallic copper–lanthanide oxides 2CuO·CeO₂ and 3CuO·Ln₂CuO₄ (Ln = La, Pr, Nd) was studied by H₂-TG/DTA and H₂-TPR. All systems exhibit two main reduction steps accompanied by mass losses in the temperature range 20–1000 °C. The first step was attributed to CuO reduction, whereas the second step is due either to copper reduction in the Ln₂CuO₄ phase with the concomitant formation of Ln₂O₃ or to the surface reduction of CeO₂. The products were characterized by XRD, SEM, EDX, and BET techniques and are better described as supported copper type materials. They were active for the mesityl oxide (4-methyl-2-penten-2-one) gas phase hydrogenation.     

Polymerisation of styrene using Y, USY and β zeolites as catalysts

The homopolymerisation of styrene is studied in the presence of Y, USY and beta zeolites. High molecular weight polymers, in the range 0.7 × 10⁶–1 × 10⁶, are obtained in good yields. The activity of zeolite beta is only slightly increased by calcination of the as-synthesised material, pointing to an important role of the zeolite outer surface. The influence of the catalyst acidity upon the polymer molecular weight is evaluated by the use of dealuminated zeolites. This revised version was published online in July 2006 with corrections to the Cover Date.     

Steroid bioconversion: Towards green processes

There is an increasing trend towards reducing the use of organic solvents in industry due to environmental constraints and the adoption of green chemistry guidelines. To overcome the low volumetric productivity of aqueous bioconversion systems involving sparingly water soluble hydrophobic compounds, processes are being developed and designed to incorporate green solvent such as supercritical fluids, ionic liquids and natural oils, and liquid polymers, among others as an alternative to organic solvents. Moreover, processes are developed and redesigned to use/reuse chemicals and reagents derived from waste or renewable feed stocks in order to diminish E-factors.In this work, the use of green solvents as key components in the bioconversion media for a multi-step microbial bioconversion was assessed in a suspended whole cell system, combined with the use of by-products as raw materials, ultimately used as carbon source for cell growth and as sterol substrate for bioconversion. The model system is the selective cleavage of the side-chain of β-sitosterol performed by free resting cells of Mycobacterium sp. NRRL B-3805, a well-established industrial multi-enzymatic process involving the use of nine catabolic enzymes in a 14-step metabolic pathway.Bioconversion yields in silicone media were higher than the ones obtained in polyethylene glycol (PEG), polypropylene glycol (PPG) and ionic liquids, as well as in dioctyl phthalate (DOP), an organic solvent that has previously been shown to allow high conversion yields. Total conversion of 12 mM substrate in silicone media was consistently obtained at the end of 120-h bioconversion runs. Similar bioconversion profiles were attained during a 50-fold scale-up, maintaining constant the power consumption per unit of volume.     

Phase equilibria of hydrates from ternary mixtures of methane + ethane + propane and methane + propane + carbon dioxide

Hydrate–liquid–vapour (HLV) equilibrium of aqueous clathrates formed from gas mixtures can be complex compared to hydrates formed with single guests. Typically, pressure and temperature are controlled to obtain these data, but for multicomponent systems, it is necessary to control/report more intensive variables, namely, composition. Metastability, manifested as impractically long experimental times, has been reported to be a challenge with some multicomponent systems. We present HLV equilibrium conditions of two ternary gas mixtures: methane + ethane + propane (90:7:3 molar ratio) and methane + propane + carbon dioxide (55:5:40 molar ratio). Conditions varied in the temperature range of 275–285 K and the pressure range of 1.24–4.75 MPa. Experimental standard uncertainties were on average 0.10 K and 0.005 MPa for methane + ethane + propane and 0.19 K and 0.005 MPa for methane + propane + carbon dioxide. Our technique allowed us to bypass the limitations reported in the literature and provided fast, reproducible HLV equilibria for gas-dominated systems.     

Foot-turistic multimedia: designing interactive multimedia installations for shoe shops

The amount of money spent in a store is positively correlated with the amount of time spent inside. We argue this is an opportunity for multimedia installations that can entertain shoppers and promote interaction with the shop??s products. This was the main principle behind our design idea for two interactive installations specifically conceived for shoe shops. We present two applications of interactive multimedia to shoe shopping: an interactive semantic mirror and an interactive window logo. We also describe the results of ethnographic studies, before and after the design process. Our contribution is two-fold: (i) we develop and apply a new multimedia architecture that combines RFID in-store technology with high-end motion detection algorithms, and (ii) we describe one of the first few studies about multimedia installations for improving the shoe shopping experience, in what we call ??foot-turistic?? interactions.     

Metal Triflates Incorporated in Mesoporous Catalysts for Green Synthesis of Fine Chemicals

Strong Lewis acid SnTf-MCM-41 and SnTf-UVM-7 catalysts with unimodal and bimodal pore systems were prepared in a two-step synthesis in which the triflic acid (Tf) was incorporated into previously synthesized mesoporous tin-containing silicas. The Sn incorporation inside the pore walls was carried out through the Atrane method. The SnTf-UVM-7 catalysts were prepared by aggregating nanometric mesoporous particles defining a hierarchic textural-type additional pore system. Catalysts with different Si/Sn ratios in the range 21.8–50.8 for SnTf-MCM-41 and 18.4 for SnTf-UVM-7 were found to be efficient catalysts for the acylation of aromatics and heteroaromatics. Under microwave irradiation the reaction was possible even with acetic acid. The selectivity to the desired product (o-hydroxyacetophenone for phenol) or the unfavored three-substituted five ring heterocycles was dramatically increased under these conditions. The process is green, environmentally safe, and heterogeneous.     

A methodology to design the link cost functions for impairment aware routing algorithms in optical networks

We propose a methodology to design the link cost function and, consequently, a systematic form to design a RWA algorithm. We call this methodology link cost function design (LCFD) and it consists of four steps: The choice of the link cost function input variables, the expansion of the cost function in terms of a series, the selection of an overall network performance indicator as the optimization target, and finally, the execution of an optimization process to find the series coefficients that optimize the network performance indicator based on off-line network simulations. The optimization process is performed by a computational intelligence technique, the particle swarm optimization. The proposed methodology (LCFD) is used to design an adaptive IA-RWA algorithm, which we call Power Series Routing (PSR). The effectiveness of both methodology and IA-RWA algorithm is investigated. The PSR is compared with other algorithms found in the literature by means of computational simulations and our proposal presented lower blocking probabilities with shorter computation time. Furthermore, we investigate the sensitivity and the ability of the proposed PSR to adapt itself to topological changes in the network due to both link/node addition/failure. We also investigate the behavior of the PSR in a scenario where the traffic load distribution is randomly chosen (non-uniform traffic), and we compared it to other three routing algorithms.     

Determination of bixin and norbixin in meat using liquid chromatography and photodiode array detection

The development of an analytical method that enables routine analysis of annatto dye, specifically bixin and norbixin, in meat tissue is described. Liquid-solid extraction was carried out using acetonitrile. Analysis was by HPLC with photodiode array detection using two fixed wavelengths (458 and 486 nm). The possibilities of ion trap mass spectrometry (MS) were also assessed. Method performance characteristics, according to Commission Decision 2002/657/EC, were determined, with recoveries between 99 and 102% and calibration curves being linear in the 0.5–10 mg kg^?1 range. The limit of quantification was 0.5 mg kg^?1.     

Phase precipitation and phase stability in nimonic 263

Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermodynamic calculations were employed to study the phase stability and phase precipitation in the Ni-based superalloy Nimonic 263. The major precipitates at temperatures below 900 °C were gamma-prime and eta (Ni₃Ti), with the eta phase starting to precipitate at the expense of the gamma-prime phase after prolonged annealing. The eta precipitates had a thin-plate morphology and formed a regular Widmanstätten pattern. They had a fixed orientation relationship with the fcc matrix. Very fine particles of M₂₃C₆ also precipitated intragranularly, and they had a cube-on-cube orientation relationship (OR) with the fcc matrix. Intragranular precipitation of a very fine cylindrical MC carbide was also observed. Grain-boundary (GB) precipitates were mostly M₂₃C₆, with a small fraction of MC. Based on the experimental results, a time-temperature-transformation (TTT) diagram was constructed. The experimental results were compared to thermodynamic predictions, and good agreement was observed. The calculations correctly predicted almost all the major phases and their stability temperature ranges. The experimental and calculation results, together, depict a clearer picture of phase stability in the alloy.