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La gran mayoría de los protocolos de blanqueamiento actuales sugieren una duración del tratamiento de dos semanas, con concentraciones del 16% de peróxido de carbamida. Pero esto no quiere decir que, tras este tiempo, aunque se consigan resultados satisfactorios, se obtenga el máximo grado de blanqueamiento, y es por ello que en este estudio se propone un tratamiento de blanqueamiento dental durante un periodo de 6 semanas. El proceso de oxidación del peróxido finaliza pasadas dos horas desde su aplicación en la superficie del esmalte, por tanto, este tiempo de aplicación diario sería suficiente para conseguir el efecto deseado sin la necesidad de extenderlo a 6-8 horas diarias, es por este motivo por el que en el presente estudio se emplea un régimen de aplicación diurno. En este estudio, se pretende comparar dos protocolos distintos de seis semanas de duración, uno con la aplicación del agente blanqueante días alternos y otro cada 3 días, para determinar la eficacia de cada uno y analizar tras este periodo de tiempo cuál es el grado de blanqueamiento obtenido y la variación de la sensibilidad en ambos protocolos....., Most of the protocols established today suggest a period of two weeks for home bleaching with concentrations of 16% carbamide peroxide; however, this does not mean that after this time, althought satisfactory results are achieved, the maximum degree of bleaching is obtained. Since the peroxide decomposition process is completed after the first two hours of its application, this daily time would be sufficient to achieve the desired effect, without the need to extend it to 6-8 hours daily. In this study, the aim is to compare two different 6-week protocols, one with the application of the bleaching agent every other day and the other every 3 days, to determine the effficacy of each one and to analyze after this period of time the degree of bleaching obtained and the variation in sensitivity in both protocols.

The main aim of this study is to carry out a qualitative and semiquantitative analysis of tannin extracts as an alternative to the official analysis method ISO 14088 – IUC 32, so that a correlation between the two methods is established. From the point of view of the chemical composition, tannins are classified into two major groups: i) condensed tannins, also called flavanols or catechins, and ii) hydrolysable tannins, also called pyrogallic tannins. Today, the most widely used conventional extracts are quebracho, mimosa, chestnut, and tara. Quebracho and mimosa are condensed tannins, whereas chestnut and tara are hydrolysable tannins. The following extracts were used in this study: tara powder, commercial mimosa and quebracho extracts and extracts derived from grape seed, containing both condensed and hydrolysable extracts. The development of this new method will allow a faster and less expensive estimate of the amount of tannins present in a tannin extract., Peer Reviewed, Postprint (published version)

EPDM rubber is widely used in a diverse type of applications, such as the automotive, industrial and construction sectors among others. Due to its appealing features, the consumption of vulcanized EPDM rubber is growing significantly. However, environmental issues are forcing the application of devulcanization processes to facilitate the recovery, which has led rubber manufacturers to implement strict quality controls. Consequently, it is important to develop methods for supervising the vulcanizing and recovering processes of such products. This paper deals with the supervision process of EPDM compounds by means of Fourier transform mid-infrared (FTIR) spectroscopy and suitable multivariate statistical methods. A nondestructive and expeditive classification approach was applied to a sufficient number of EPDM samples with different applied processes, that is, with and without application of vulcanizing agents, vulcanized samples and microwave treated samples. First the FTIR spectra of the samples is acquired and next it is processed by applying suitable feature extraction methods, i.e., principal component analysis (PCA) and canonical variate analysis (CVA) to obtain the latent variables to be used for classifying test EPDM samples. Finally, the k-NN (k nearest neighbor) algorithm was used in the classification stage. Experimental results prove the accuracy of the proposed method and the potential of FTIR spectroscopy in this area, since the classification accuracy can be as high as 100%., Postprint (author's final draft)

Products based on ethylene-propylene-diene m-class (EPDM) and natural rubber (NR) are widely used in a different applications, including the automotive industry, heating, ventilation, and air conditioning applications, roofing systems, or the construction sector among others. The growing demand of these types of polymeric products has forced rubber industry to implement strict control schemes to ensure the specifications of the final products. The focus of this paper is the identification of different treatment types of NR and EPDM samples without any preceding analytical treatment to carry out a fast and reliable supervision of the vulcanization processes to improve the quality of the final rubber products. To this end, the thermogravimetric analysis (TGA) technique is applied in combination with the principal component analysis (PCA) and canonical variate analysis (CVA) multivariate feature extraction methods and the k-nearest neighbor (k-NN) classifier. Experimental results prove the suitability of the proposed approach and the potential of the TGA method for a fast supervision of the vulcanization processes. Using the information provided by the TGA technique in association with the PCA + CVA + k-NN approach, the system achieved 100% identification accuracy., Peer Reviewed, Postprint (author's final draft)

Des de l'antiguitat el safrà ha estat una espècia molt apreciada per les seves propietats. Amb el temps i degut al decreixement de l’economia mundial moltes de les empreses productores de safrà han reduït les vendes o fins i tot han hagut de tancar. Amb la recuperació econòmica moltes empreses han decidit tornar a produir i buscar noves alternatives per a aprofitar bio-residus i tenir un procés molt més rendible. El cultiu del safrà (espècia) és un procés molt precís i només s'aprofita d'una part de la planta generant un bio-residu important (tèpals i estams), que fins el dia d’avui no se li ha donat cap sortida comercial. En aquest treball es pretén fer una recerca exhaustiva de la composició de les flors i de cadascuna de les parts, mètodes de conservació de la flor i possibles aplicacions, com poden ser el tenyit, condiment en l’alimentació, fabricació de medicaments.

Paperboard is widely used in different applications, such as packaging and graphic printing, among others. Consumption of recycled paper is growing, which has led the paper-mill packaging industry to apply strict quality controls. This means that it is very important to develop methods to test the quality of recycled products. In this article, we focus on determining the recoveredfiber content of paperboard samples by applying Fourier transform mid-infrared (FT-MIR) spectroscopy in combination with multivariate statistical methods. To this end, two very fast, nondestructive approaches were applied: classification and quantification. The first approach is based on classifying unknown paperboard samples into two groups: high and low recovered-fiber content. Conversely, under the quantification approach, the content of recovered fiber in the incoming paperboard samples is determined. The experimental results presented in this article show that the classification approach, which classifies unknown incoming paperboard samples, is highly accurate and that the quantification approach has a root mean square error of prediction of about 4.1, Peer Reviewed, Postprint (author's final draft)

Peer Reviewed, Postprint (author's final draft)

Recycled paper is extensively used worldwide. In the last decades its market has expanded considerably. The increasing use of recycled paper in papermaking has led to the production of paper containing several types of impurities. Consequently, wastepaper mills are forced to implement quality control schemes for evaluating the incoming wastepaper stock, thus guarantying the specifications of the final product. The main objective of this work is to present a fast and reliable system for identifying different paper types. Therefore, undesirable paper types can be refused, improving the performance of the paper machine and the final quality of the paper manufactured. For this purpose two fast techniques, i.e., Fourier transform mid-infrared (FTIR) and reflectance near-infrared (*IR) were applied to acquire the infrared spectra of the paper samples. *ext, four processing multivariate methods, i.e., principal component analysis (PCA), canonical variate analysis (CVA), extended canonical variate analysis (ECVA) and support vector machines (SVM) were employed in the feature extraction –or dimension reduction– stage. Afterwards, the k nearest neighbors algorithm (k**) was used in the classification phase. Experimental results show the usefulness of the proposed methodology and the potential of both FTIR and *IR spectroscopic methods. Using the FTIR spectrum in association with SVM and k** the system achieved maximum classification accuracy of 100%, whereas using the *IR spectrum in association with ECVA or SVM and k** the system achieved maximum classification accuracy of 96.4%, Postprint (published version)

The increasing use of secondary fiber in papermaking has led to the production of paper containing a wide range of contaminants. Wastepaper mills need to develop quality control methods for evaluating the incoming wastepaper stock as well as testing the specifications of the final product. The goal of this work is to present a fast and successful methodology for identifying different paper types. In this way, undesirable paper types can be refused, thus improving the runnability of the paper machine and the quality of the paper manufactured. In this work we examine various types of paper using information obtained by an appropriate chemometric treatment of infrared spectral data. For this purpose, we studied a large number of paper sheets of three different types (namely coated, offset and cast-coated) supplied by several paper manufacturers. We recorded Fourier transform infrared (FTIR) spectra with the aid of an attenuated total reflectance (ATR) module and near-infrared (NIR) reflectance spectra by means of fiber optics. Both techniques proved expeditious and required no sample pretreatment. The primary objective of this work was to develop a methodology for the accurate identification of samples of different paper types. For this purpose, we used the chemometric discrimination technique extended canonical variate analysis (ECVA) in combination with the k nearest neighbor (kNN) method to classify samples in the prediction set. Use of the NIR and FTIR techniques under these conditions allowed paper types to be identified with 100% success in prediction samples., Peer Reviewed, Postprint (published version)