Use of capillary electrophoresis with UV detection to compare the phenolic profiles of extra‐virgin olive oils belonging to Spanish and Italian PDOs and their relation to sensorial properties

BACKGROUND: There is much interest in foods that belong to Protected Designations of Origin (PDO) because the quality and other essential and exclusive characteristics are guaranteed because of a particular geographical environment. We have used a capillary electrophoretic method for the simple, rapid and simultaneous characterization and quantification of the polyphenolic fraction of extra‐virgin olive oil from different PDOs (18 compounds in less than 7 min). To demonstrate the usefulness of this method, we have analyzed 16 samples of a Spanish PDO and nine other samples belonging to an Italian PDO (n = 5). RESULTS: In this way, it was possible to compare the phenolic profiles of the oils of different zones of the same PDO, as well as the phenolic profiles of Spanish and Italian extra‐virgin olive oils. Univariate statistics were used for differentiating the oils produced in each PDO. Furthermore, the correlations among several of the phenolic compounds present in the extracts of olive oil and its sensorial properties were checked. decarboxylated oleuropein aglycon (DOA) (b) (peak 6) was the compound more related to the bitterness of the oils, Ac Pin (peak number 4) and the unidentified peak with t_mig 4.025 min played an important role in the pungent taste of the oils, and these two latter compounds and the peak 13 seemed to be related to the fruitiness of the oils. CONCLUSIONS: The electrophoretic method described in the current work has the ability to detect and quantify simultaneously 18 phenolic compounds (belonging to five different families) in less than 7 min. This technique could improve the characterization of this polar fraction and determine the geographical origin of olive oils or detect possible ‘PDO markers’. In fact, capillary electrophoresis coupled to statistical analysis enabled discrimination among olive oils belonging to two different PDOs considering eight phenolic compounds present in the extracts, and also identification of the phenolic compounds which could have more influence on several sensory attributes such as bitterness, pungency and fruitiness. Copyright © 2009 Society of Chemical Industry     

Oxidation of La–Sr–Mn-Coated Interconnector Alloys for Steam Electrolysis Under Pressure in Pure Oxygen and in Pure Steam

Pressurized steam electrolysis enables an efficient conversion of electric power from renewable energy sources into hydrogen for power-to-liquids processes. The interconnector material Crofer 22 APU, uncoated and coated by La_1?x Sr _x MnO₃ (LSM), deposited by thermal spray and by roll coating was studied in pure water vapor and pure oxygen at 850 °C and 30 bar. The uncoated Crofer 22 APU forms in both atmospheres a homogeneous oxide scale from an inner Cr₂O₃ and an outer MnCr₂O₄ layer. The chromia is locally undergrown by pits of MnCr₂O₄. With the LSM coating, the oxide scale is notably thinner in water vapor and the formation of pits is significantly reduced. In oxygen, this effect of the LSM coating is less pronounced. Chromium from volatile species was detected in the LSM coating, more in oxygen than in water vapor. After 3000 h in pure oxygen, Crofer 22 APU with thermally sprayed LSM shows breakaway oxidation.     

Gelatine/PLLA sponge-like scaffolds: morphological and biological characterization

Biodegradable synthetic polymers such as poly(lactic acid) are widely used to prepare scaffolds for cell transplantation and tissue growth, using different techniques set up for the purpose. However the poor hydrophilicity of these polymers represents the main limitation to their use as scaffolds because it causes a low affinity for the cells. An effective way to solve this problem could be represented by the addition of biopolymers that are in general highly hydrophilic. The present work concerns porous biodegradable sponge-like systems based on poly(L-lactic acid) and gelatine. Morphology and porosity characteristics of the sponges were studied by scanning electron microscopy and mercury intrusion porosimetry respectively. Blood compatibility was investigated by bovine plasma fibrinogen adsorption test and platelet adhesion test. The cell culture method was used in order to evaluate the ability of the matrices to work as scaffolds for tissue regeneration. The obtained results indicate that the sponges have interesting porous characteristics, good blood compatibility and above all good ability to support cell adhesion and growth. In fact viable and metabolically active animal cells were found inside the sponges after 8 weeks in culture. On this basis the systems produced seem to be good candidates as scaffolds for tissue regeneration.     

Non-minimal sums of disjoint products

We refine a conjecture of M.O. Locks and J.M. Wilson [Reliab Eng Syst Saf 1994;46:283–286] regarding disjoint forms of the Abraham reliability problem. We also present other examples of reliability problems with the interesting property that their minimal disjoint forms do not arise from the familiar tautology .     

Inverse scattering from phaseless measurements of the total field on open lines

A new solution approach to inverse scattering from aspect-limited phaseless measurements of the total field is introduced and discussed. In analogy with the case of measurements on closed curves [J. Opt. Soc. Am. A21, 622 (2004)], the procedure splits the problem into two different steps. In the first step, amplitude and phase of the scattered field are estimated from only amplitude information of the total field. By properly extending the concept of reduced radiated field to the case of scattered fields (as a function of both illumination and measurement variables) and taking advantage of the properties of the square amplitude distribution of the total field, criteria are given for an optimal choice of the measurement setup and a successful retrieval. Then the complex permittivity profile is reconstructed in the second step, starting from the scattered fields estimated in the previous step. Numerical examples are provided to assess the effectiveness of the whole chain in the presence of noise-corrupted data and the relevance of the representation introduced for the scattered fields.     

Comprehensive study of bioanalytical platforms: xanthine oxidase

A comprehensive study of a general bioanalytical platform for biosensor applications is presented using xanthine oxidase (XnOx) as a case study within the framework of developing approaches of broad applicability. In this context, emphasis is placed on amperometric biosensors based on XnOx, which has been immobilized by covalent binding to gold electrodes modified with dithiobis-N-succinimidyl propionate. The immobilized XnOx layers have been characterized using atomic force microscopy under liquid conditions and quartz crystal microbalance techniques. In addition, spatially resolved mapping of enzymatic activity has been carried out using scanning electrochemical microscopy. Redox dyes of phenothiazine derivatives, specifically, thionine and methylene blue, have been found to work well as electron acceptors for reduced XnOx. The kinetic parameters and equilibrium constants of the mediated enzymatic oxidation of xanthine in the presence of the above-mentioned redox dyes have been calculated. The response of the enzymatic electrode to varying xanthine concentrations has been obtained in the presence of thionine or methylene blue as redox mediator in solution. Under these conditions, xanthine could be determined amperometrically at +0.2 V versus SSCE.     

Ceramic dielectric mirrors for the terahertz range

We have produced a rigid dielectric terahertz mirror by tape casting and sintering 25 stacked ceramic layers of alumina and alumina-zirconia. Our structure shows a pronounced stop band between 0.3 and 0.38 THz. The experimental data agree well with transfer matrix calculations.     

Anion exchange membrane fuel cell modelling

A parametric model predicting the performance of a solid polymer electrolyte, anion exchange membrane fuel cell (AEMFC), has been developed, in Matlab environment, based on interrelated electrical and thermal models. The electrical model proposed is developed by modelling an AEMFC open-circuit output voltage, irreversible voltage losses along with a mass balance, while the thermal model is based on the energy balance. The proposed model of the AEMFC stack estimates its dynamic behaviour, in particular the operating temperature variation for different discharge current values. The results of the theoretical fuel cell (FC) stack are reported and analysed in order to highlight the FC performance and how it varies by changing the values of some parameters such as temperature and pressure. Both the electrical and thermal FC models were validated by comparing the model results with experimental data and the results of other models found in the literature.     

Predictive repair scheduling of wind turbine drive‐train components based on machine learning

We devise a methodology to predict failures in wind turbine drive‐train components and quantify its utility. The methodology consists of two main steps. The first step is the set up of a predictive model for shutdown events, which is able to raise an alarm in advance of the fault‐induced shutdown. The model is trained on data for shutdown events retrieved from the alarm log of an offshore wind farm. Here, it is assumed that the timely prediction of low‐severity events, typically caused by abnormal component operation, allows for an intervention that can prevent premature component failures. The prediction models are based on statistical classification using only supervisory control and data acquisition (SCADA) data. In the second step, the shutdown prediction model is combined with a cost model to provide an estimate of the benefits associated with implementing the predictive maintenance system. This is achieved by computing the maximum net utility attainable as a function of the model performance and efficiency of intervention carried out by the user. Results show that the system can be expected to be cost‐effective under specific conditions. A discussion about potential improvements of the approach is provided, along with suggestions for further research in this area.