Modeling of solid—liquid adsorption: Effects of adsorbent loads on model parameters

The adsorption of cobalt phthalocyanine dye onto activated carbon in a continuous stirred tank adsorber was studied. The variables investigated were: adsorbent mass, adsorbent particle size and fluid flowrate. Several models based on film, pore and surface diffusion were constructed and fitted to the experimental data. Experimental results showed: (i) the increasing importance of the film mass transfer resistance for increasing adsorbent loads; (ii) the increasing importance of the surface diffusion mechanism for increasing adsorbent loads; and (iii) the better discrimination among different models for higher adsorbent loads and lower flowrate.     

Integration of virtual and real environments for engineering service-oriented manufacturing systems

Engineering frameworks are currently required to support the easy, low-cost, modular and integrated development of manufacturing systems addressing the emergent requirements of re-configurability, responsiveness and robustness. This paper discusses the integration of 2D/3D digital software tools with Petri net based service-oriented frameworks to allow the design, configuration, analysis, validation, simulation, monitoring and control of manufacturing systems in a virtual environment and its posterior smooth migration into the real ??physical?? environment. An experimental case study was implemented to validate the proposed concepts, using the Continuum platform to design, compose, analyze, validate and simulate the Petri nets based service-oriented manufacturing control system, and the Delmia Automation^TM software suite to support the rapid prototyping and the easy simulation of the designed control solution. The experimental results prove several aspects of the proposed approach, notably the smooth migration between the design and the operation phases, one of the main objectives of the work.     

Effect of gamma and electron beam irradiation on the physico-chemical and nutritional properties of mushrooms: a review

The short shelf-life of mushrooms is an obstacle to the distribution and marketing of the fresh product. Thus, prolonging postharvest storage, while preserving their quality, would benefit the mushroom industry as well as consumers. There has been extensive research on finding the most appropriate technology for mushrooms preservation. Gamma, electron-beam and UV irradiation have been shown to be potential tools in extending the postharvest shelf-life of fresh mushrooms. Studies evaluating the effects of ionizing radiation are available mainly in cultivated species such as Agaricus bisporus, Lentinus edodes and Pleurotus ostreatus. This review comprises a comprehensive study of the effects of irradiation on physico-chemical parameters (weight, colour, texture and pH), chemical compounds including nutrients (proteins, sugars and vitamins) and non-nutrients (phenolics, flavonoids and flavour compounds), and on biochemical parameters such as enzymatic activity of mushrooms for different species and from different regions of the world.     

Metabolic profile and biological activities of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco: Studies on the essential oil and polar extracts

We investigated the metabolic profile and biological activities of the essential oil and polar extracts of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco collected in south Portugal. Gas chromatography–mass spectrometry (GC–MS) analysis revealed that oxygen-containing monoterpenes was the principal group of compounds identified in the essential oil. Camphor (40.6%) and fenchone (38.0%) were found as the major constituents. High-performance liquid chromatography with diode array detection (HPLC–DAD) analysis allowed the identification of hydroxycinnamic acids (3-O-caffeoylquinic, 4-O-caffeoylquinic, 5-O-caffeoylquinic and rosmarinic acids) and flavones (luteolin and apigenin) in the polar extracts, with rosmarinic acid being the main compound in most of them. The bioactive compounds from L. pedunculata polar extracts were the most efficient free-radical scavengers, Fe²⁺ chelators and inhibitors of malondialdehyde production, while the essential oil was the most active against acetylcholinesterase. Our results reveal that the subspecies of L. pedunculata studied is a potential source of active metabolites with a positive effect on human health.     

An unsupervised approach for fault diagnosis of power transformers

Electrical utilities apply condition monitoring on power transformers (PTs) to prevent unplanned outages and detect incipient faults. This monitoring is often done using dissolved gas analysis (DGA) coupled with engineering methods to interpret the data, however the obtained results lack accuracy and reproducibility. In order to improve accuracy, various advanced analytical methods have been proposed in the literature. Nonetheless, these methods are often hard to interpret by the decision-maker and require a substantial amount of failure records to be trained. In the context of the PTs, failure data quality is recurrently questionable, and failure records are scarce when compared to nonfailure records. This work tackles these challenges by proposing a novel unsupervised methodology for diagnosing PT condition. Differently from the supervised approaches in the literature, our method does not require the labeling of DGA records and incorporates a visual representation of the results in a 2D scatter plot to assist in interpretation. A modified clustering technique is used to classify the condition of different PTs using historical DGA data. Finally, well-known engineering methods are applied to interpret each of the obtained clusters. The approach was validated using data from two different real-world data sets provided by a generation company and a distribution system operator. The results highlight the advantages of the proposed approach and outperformed engineering methods (from IEC and IEEE standards) and companies legacy method. The approach was also validated on the public IEC TC10 database, showing the capability to achieve comparable accuracy with supervised learning methods from the literature. As a result of the methodology performance, both companies are currently using it in their daily DGA diagnosis.     

Inhibitory activity of plumbagin produced by Drosera intermedia on food spoilage fungi

BACKGROUND: The aim of this study was to investigate the growth‐inhibiting efficacy of Drosera intermedia extracts (water, methanol and n‐hexane) against four food spoilage yeasts and five filamentous fungi strains responsible for food deterioration and associated with mycotoxin production, in order to identify potential antimycotic agents. RESULTS: The n‐hexane extract showed a broad activity spectrum against all tested microorganisms, followed, in activity, by the methanol and water extracts. The major component of the n‐hexane extract was purified using a solid‐phase extraction column and identified as plumbagin. Results show that high‐purity plumbagin can be produced from D. intermedia cultures following a simple and effective isolation procedure. A sample of purified plumbagin was tested against the same panel of microorganisms and high growth‐inhibiting capacity was observed. Minimum inhibitory concentrations less than 2 µg mL^?1 were obtained against the filamentous fungi. In the case of the species Aspergillus fumigatus, A. niger and A. flavus , activities comparable to miconazole were obtained. CONCLUSION: The results obtained provided evidence of the antimycotic activity of plumbagin, suggesting that D. intermedia could be the source of an interesting compound for the food industry as an alternative to preservatives. Copyright © 2011 Society of Chemical Industry     

Structural and Catalytic Studies of a Trimethyltin Vanadate Coordination Polymer

The organotin vanadate [Me₃SnVO₃] (1) has been prepared and characterised in the solid state by powder X-ray diffraction (XRD), thermogravimetric analysis, multinuclear magic-angle spinning (MAS) NMR, IR and Raman spectroscopy. The phase purity and structure of microcrystalline 1 were confirmed by carrying out a full Rietveld structural refinement at ambient temperature and from conventional powder XRD. ⁵¹V and ¹¹⁹Sn MAS NMR data for compound 1 were in agreement with the predicted structure, showing two equally-abundant, nonequivalent Me₃Sn groups and two equally-abundant, nonequivalent vanadium atoms. The compound was applied as a catalyst for the liquid-phase epoxidation of olefins at 55 °C using tert-butyl hydroperoxide (tBuOOH) as the oxidant. The reaction rate for the different substrates followed the order cis-cyclooctene > (R)-(+)-limonene ≅ trans-2-octene > cyclododecene > styrene > 1-octene; the corresponding epoxides were the only observed products. Leaching tests indicated that the catalytic epoxidation of cyclooctene was mainly heterogeneous in nature. This paper is dedicated to Professor Ian Manners and his scientific accomplishments.     

Strongly Photosensitive and Fluorescent F8T2 Electrospun Fibers

Electrospun fibers of poly[(9,9‐dioctylfluorenyl‐2,7‐diyl)‐co‐bithiophene] (F8T2) with exceptional electro‐optical performance are obtained. The I/T characteristics measured in fibers with 7–15 µm diameter and 1 mm length show a semiconductor behavior; their thermal activation energy is 0.5 eV and the dark conductivity at RT is 5 × 10^?9 (Ω cm)^?1. Besides exhibiting a photosensitivity of about 60 under white light illumination with a light power intensity of 25 mW · cm^?2, the fibers also attain RT photoluminescence in the cyan, yellow, and red wavelength range under ultraviolet, blue, and green light excitation, respectively. Optical microscope images of F8T2 reveal homogeneous electrospun fibers, which are in good agreement with the uniformly radial fluorescence observed.

     

Using torque sensitivity analysis in accessing Friction Stir Welding/Processing conditions

The use of Friction Stir Processing (FSP) techniques for the joining and/or transforming of metallic materials is being object of intensive research since the earliest development of the Friction Stir Welding (FSW) technology in 1991. Despite of this, an accurate understanding of the main welding/processing mechanisms and its relation with the process parameters is still missing. Current paper intends to provide some further insight on this subject by discussing the relations between processing parameters, classified as independent variables, and the corresponding welding results, classified as dependent variables, using torque sensitivity analysis. The relation between base materials properties, plate thickness, welding conditions and torque evolution were also explored, which constitutes a novelty relative to the previous studies on this subject.