Dipole–dipole interaction in superparamagnetic nanocrystalline Fe63.5Cr10Si13.5B9Cu1Nb3

Cr-substituted Finemet-type nanocrystalline alloy (Fe63.5Cr10Si13.5B9Cu1Nb3) has been studied by differential scanning calorimetry, x-ray diffraction, Mo¨ssbauer spectroscopy, and magnetic measurements. The Curie temperature of the remaining amorphous phase decreases as the crystalline volume fraction increases, reaching values below room temperature. This feature makes the alloy adequate for studying the magnetic decoupling of the ~Fe,Si! nanocrystals at moderated temperatures and, in particular, the superparamagnetic relaxation in broad temperature and crystalline fraction ranges. It was shown that the anomalous dependence of the coercive field on the annealing temperature can be satisfactorily explained assuming a dipolar-type interaction between the crystallites.DGES del Gobierno español-PB97-1119-CO2-01Fondo de investigación del gobierno húngaro-OTKA T-030753Academia de Ciencias de Hungría-AKP 98-25 2,

Isolation of polyphenols from spent coffee grounds and silverskin by mild hydrothermal pretreatment

In the present study, a new method for isolation of polyphenols (PP) from spent coffee grounds (SCG) and coffee silverskin (CS) is described. The method consisted in a mild hydrothermal pretreatment at 120 °C, during 20 min, using a liquid to solid ratio of 20 ml/g. PP (determined as gallic acid equivalents, GAE) were the most abundant components in the extracts produced by this method, corresponding to 32.92 mgGAE/gSCG and 19.17 mgGAE/gCS, among of which, flavonoids corresponded to 8.29 and 2.73 mg quercetin equivalents/g of SCG and CS, respectively. Both extracts presented antioxidant activity but the results were higher for SCG extract, probably due to the highest content of PP present. Negligible effects (less than 1% solubilisation) were caused by the hydrothermal pretreatment on cellulose, hemicellulose and protein fractions of these materials. Some minerals elements were present in the extracts, potassium being the most abundant. Hydrothermal pretreatment under mild conditions was demonstrated to be an efficient method to recover antioxidant PP from coffee residues

Improving the accuracy of wood moisture content estimation in four European softwoods from Spain

Aim of study: To obtain improved models to predict, with an error of less than ± 2.0%, the gravimetric moisture content in four different softwoods commonly present in the Spanish and European markets, based on electrical resistance measurements. This improved moisture content estimation is useful not only for assessing the quality of wood products, especially in the case of laminated products, during the transformation and delivery process, but also for accurately monitoring the evolution of moisture in wood present in bridges and buildings, which is of great importance for its maintenance and service life improvement.Area of study: The study was carried out on samples of Scots, laricio, radiata and  maritime pines of Spanish provenances.Material and methods: On 50x50x20 mm3 solid wood samples (36 per species, 9 per condition), conditioned at 20ºC (±05ºC) and 40±5%, 65±5%, 80±5% or 90±5% Relative Humidity (RH), electrical resistance and oven-dry moisture content was measured. The Samuelsson's model was fitted to data to explain the relationship between the two variables. The accuracy of the model was evaluated by the use of an external sample.Main results: With the proposed mathematical functions the wood moisture content can be estimated with an error of ±0.9% in the four species, confirming the effectiveness of this nondestructive methodology for accurate estimation and monitoring of moisture content.Research highlights: our results allow the improvement of the moisture content estimation technique by resistance-type methodologies.Keywords: Resistance-type moisture meter; species correction.Abbreviations used: MC: Moisture content; RH: relative Humidity; R: electrical resistance; RP: wood electrical resistance measured parallel to the grain; RT: electrical resistance measured perpendicular (transversally) to the grain; GM-MC: gravimetrically measured moisture content

Hydrothermal pretreatment of spent coffee and silverskin for polyphenols recovery

Coffee is one of the most consumed beverages around the world. As a consequence of this big market, huge amounts of residues are also generated every year as a result of the coffee beans processing. Spent coffee grounds (SCG, Figure 1a), for example, are obtained in significant amounts during the process for instant coffee elaboration, and is also obtained in large amounts in restaurants, bars and cafeterias; while coffee silverskin (CS, Figure 1b) is the main residue obtained during the beans roasting step [1]. Interest in reusing these residues has increased in the last years for economic and environmental concerns. Additionally, such coffee wastes contain in their composition several compounds of interest for application in food, cosmetic and pharmaceutical areas [1]. The presence of polyphenols (PP) in SCG and CS has been reported in several studies, and some technologies have also been proposed for the recovery of these compounds from such coffee residues, among of which the use of organic solvents is usually proposed due to their efficient extraction capacity. However, the use of organic solvents generates a toxic effluent that needs to be treated before discharging to the environment. As an alternative to avoid this problem, the present study evaluated the possibility of recovering PP by hydrothermal pretreatment of SCG and CS. By using this strategy, the residues are submitted to a reaction using only water as extraction solvent under higher temperature conditions than those usually employed for extraction with organic solvents, and the use of these toxic chemicals is avoided. The hydrothermal pretreatment of SCG and CS consisted in using 20 mL of distilled water to each gram of residue, and the reactions were maintained at 120 ºC during 20 min. The total amount of PP in the extracts was quantified as gallic acid equivalents (GAE). The extracts produced under these conditions contained 32.9 mg GAE/g SCG and 19.2 mg GAE/g CS, among of which, flavonoids corresponded to 25% and 14% of the total PP in SCG and CS, respectively. These results were higher than the amounts recovered in previous studies using organic solvents (methanol and ethanol) as extraction agent [2, 3]. It was then concluded that is possible to use a hydrothermal pretreatment to efficiently recover PP from coffee wastes. Further studies will be focused on the selection of the extraction conditions that maximize the recovery results

Caso Clínico ARP nº 21: Qual o seu Diagnóstico?

info:eu-repo/semantics/publishedVersio

Argon assisted chemical vapor deposition of CrO2_2: an efficient process leading to high quality epitaxial films

A comparative study of the structural, microstructural and magnetic properties of CrO$_2$ thin films grown onto (110) and (100) TiO$_2$ rutile single crystal substrates by chemical vapor deposition (CVD), using CrO$_3$ as chromium precursor and either oxygen or argon as carrier gas is presented. Our results show that growth under argon carrier gas leads to high quality CrO$_2$ epilayers with structural and magnetic properties similar to those obtained using the more standard oxygen carrier gas. Furthermore, we interpret the larger magnetic coercivity observed for the (110) oriented films in terms of their microstructure, in particular of the highest strain and edge roughness of the building structures of the CrO$_2$ epilayers, which are settled by the substrate crystallographic orientation.Comment: 27 pages, 2 tables, 8 figure

The thickness of a liquid layer on the free surface of ice as obtained from computer simulation

Molecular dynamic simulations were performed for ice Ih with a free surface by using four water models, SPC/E, TIP4P, TIP4P/Ice and TIP4P/2005. The behavior of the basal plane, the primary prismatic plane and of the secondary prismatic plane when exposed to vacuum was analyzed. We observe the formation of a thin liquid layer at the ice surface at temperatures below the melting point for all models and the three planes considered. For a given plane it was found that the thickness of a liquid layer was similar for different water models, when the comparison is made at the same undercooling with respect to the melting point of the model. The liquid layer thickness is found to increase with temperature. For a fixed temperature it was found that the thickness of the liquid layer decreases in the following order: the basal plane, the primary prismatic plane, and the secondary prismatic plane. For the TIP4P/Ice model, a model reproducing the experimental value of the melting temperature of ice, the first clear indication of the formation of a liquid layer appears at about -100 Celsius for the basal plane, at about -80 Celsius for the primary prismatic plane and at about -70 Celsius for the secondary prismatic plane.Comment: 41 pages and 13 figure

Eclipsing Binaries Showing Light Time Effect

Four eclipsing binaries, which show apparent changes of period, have been studied with respect to a possible presence of the light time effect. With a least squares method we calculated new light elements of these systems, the mass function of the predicted third body, and its minimum mass. We discuss the probability of the presence of such bodies in terms of mass function, changes in radial velocity and third light in solution of light curves.Comment: 4 pages, 4 figures, 1 table, conference proceeding

Spain 2011 pension reform

The aim of this paper is to evaluate the impact of the Spanish pension reform enacted in 2011. We use an accounting model with heterogeneous agents and overlapping generations in order to project revenues and expenditures of the pension system for the next four decades. Specifically, we analyze the impact of changes in the replacement rate, in the period of calculation and the delay of the retirement age. We obtain results under two alternative migration scenarios: (i) a combination of the latest figures released by the INE, which forecast a reduced annual immigration net flow of some 70,000 persons; and (ii) a revised scenario featuring a more generous hypothesis concerning this net flow. We demonstrate that the results show that these three changes instigated by the reform could imply a savings of about 3 percentage points of GDP in 2051. However, we couldn’t include in the evaluation the sustainability factor (that transform the Spanish system in a defined contribution scheme) that will start in 2027 due to the lack of details in the text of the Reform. Finally, we analyze the changes in average pensions by gender, skill, and nationalit