Although carbon dioxide (CO2) is well known as one of the major green-house gases, it is also an economical C1 resource. Thus, CO2 has been regarded as an appealing starting material for the synthesis of polymers, like polycarbonates by the reaction with epoxides. Herein the reaction between natural epoxidized soybean oil (ESO), propylene oxide (PO) and CO2 under high pressure (4.0 MPa) with the presence of Co-Zn double metal cyanide (Co-Zn DMC) catalyst was studied. Temperature and reaction time were varied accordingly and the products obtained were characterized by FTIR, GPC and 1H NMR. The results obtained indicate the formation of polycarbonates in the samples collected with yields vary from 60 to 85%. The number average molecular weight (Mn) of the resultant polymer prepared at reaction temperature of 80 °C and reaction time of 6 h can reach up to 6498 g/mol.
Zhu, Y.; Ahmad, M.; Yang, L.; Misovich, M.; Yaroshchuk, A.; Bruening, M.L. Journal of membrane science Vol. 537, p. 1-9 DOI: 10.1016/j.memsci.2017.05.043 Data de publicació: 2017-09-01 Article en revista
Nafion membranes coated with polyelectrolyte multilayers (PEMs) exhibit outstanding monovalent/divalent cation electrodialysis selectivity in a single-membrane cell. Nevertheless, the high cost of Nafion and the extensive pretreatments required for polyelectrolyte adsorption on this surface may preclude the use of these membranes in many applications. This work reports that native aliphatic polyamide Fujifilm type 1 cation-exchange membranes modified with protonated poly(allylamine) (PAH)/poly (4-styrenesulfonate) (PSS) films also show extremely high K+/Mg2+ cation selectivities in ED with a single-membrane cell. Even with 0.1 M salt in the source phase, the K+/Mg2+ selectivity is >1000. The very low transfer of divalent cations implies that the PEM forms a complete, continuous coating on the smooth Fujifilm surface. Moreover, for a membrane coated on both sides, the PEM on the anode side is responsible for most of the selectivity. However, the current efficiency is only ~0.6 for PAH/PSS-modified Fujifilm or Nafion membranes. Adsorption of highly water-swollen (PDADMAC/PSS)n films on Nafion membranes leads to high K+/Mg2+ and Li+/Co2+ selectivities in ED, and the monovalent cation current efficiency reaches 0.8.
Heidarzadeh, N.; Mehdi Rafizadeh, M.; Faramarz Afshar Taromi, F.; del Valle, LJ.; Franco, M.; Puiggali, J. Thermochimica acta Vol. 654, p. 101-111 DOI: 10.1016/j.tca.2017.05.011 Data de publicació: 2017-08-10 Article en revista
Thermal stability and degradation kinetics have been studied for a series of aliphatic-aromatic copolyesters where the terephthalate content was varied between 30 mol-% and 70 mol-%. Succinate, adipate and sebacate were considered as the aliphatic dicarboxylate unit. All copolyesters were synthesized with a perfect random distribution by a thermal transesterification process from the corresponding homopolyesters.
A complex degradation was deduced for all copolymers taking into account the increment of the activation energy with conversion. In fact, thermogravimetric curves showed a minor decomposition process in the low conversion region that was more significant for the succinate derivative and specifically for that having the lowest aromatic content. The sebacate derivative was characterized by the presence of an additional and minor decomposition process that took place at the highest conversion.
All copolyesters were defined by a major decomposition process, which has similar values of activation energy regardless of the method used to calculate them (e.g. Kissinger, KAS or Friedman methodologies). This decomposition reaction followed a A4 Avrami-Erofeev mechanism when Coats-Redfern and Criado methodologies were applied. In summary, all the studied copolymers thermally decompose following a complex process but in all cases the main degradation step corresponds to a similar degradation mechanism.
This work reports on a green synthetic route to produce concentrated aqueous dispersions of silver nanoparticles (AgNP)
employing high-intensity ultrasound (US) and chitosan (CS) as a non-toxic reducing agent for Ag1 salts and AgNP stabilizer. The sonication simultaneously boosted the synthesis and improved the stability of the AgNP, capping them with CS. Hybrid AgNP-CS antimicrobial dispersions, stable for at least 6 months, were synthesized in a simple single step process. The use of US allowed for applying relatively mild processing temperatures (608C) and reaction time between 30 min and 3 h to obtain concentrated disper- sions of AgNP that otherwise could not be obtained even after 72 h under mechanical stirring at the same reaction conditions. Upon sonication spherical AgNP-CS with a size between 60 and 100 nm were generated, in contrast to the average diameter of 200 nm of the particles obtained by stirring. The antibacterial efficiency of the AgNP-CS hybrids was evaluated against the medically relevant pathogens Staphylococcus aureus and Escherichia coli. The US-synthesized AgNP-CS showed more than 3-fold higher antibacterial activity compared to the particles obtained under stirring, due to their higher concentration and smaller size.
Gimenez, F.; Espriu-Gascon, A.; Bastos-Arrieta, J.; Pablo, J. Journal of Archaeological Science: Reports Vol. 14, p. 174-180 DOI: 10.1016/j.jasrep.2017.05.055 Data de publicació: 2017-08-01 Article en revista
The effect of the presence of NaCl on the synthesis of Egyptian blue pigment (cuprorivaite, CaCuSi4O10) was studied through experiments in which different amounts of NaCl were introduced in the initial mixture of reactants. The solids synthesized were characterized by X-ray Diffraction, Field Emission Scanning Electron Microscopy (FE-SEM) coupled to Energy-Dispersive Spectrometry (EDS) and High Resolution Transmission Electron Microscopy (HR-TEM) coupled to EDS. The main result of the experiments was that Egyptian blue formation was inhibited in the presence of NaCl, actually, almost no cuprorivaite was found in > 10% NaCl experiments and the solids synthesized in NaCl were always green instead of the characteristic blue of the Egyptian blue pigment. The solids synthesized in the presence of NaCl, a mixture of wollastonite (CaSiO3) and a Cu-rich amorphous phase, probably corresponded to the composition of the pigment known as Egyptian green. Considering the usual presence of NaCl on some of the raw materials used for the pigment fabrication, Egyptian artisans had to be very careful on selecting the reactants for the fabrication of the pigment (quartz would be much more suitable than Egyptian sand, and ash plants than natron) or they incorporated a process of purification of the reactants in order to eliminate chlorides prior to the synthesis.
Composites formed by poly(3,4-ethylenedioxythiophene) and alumina (PEDOT/Al2O3) have been prepared by in situ anodic polymerization. For this purpose, the stability of 1:1 and 4:1 monomer:alumina aqueous solutions has been examined as a function of the pH (2.3, 4.0, 7.0, 8.8, or 10.8). Results indicate that the monomer behaves as a dispersant that remains stable at the studied basic pHs despite they are close to the isoelectric point of alumina. Although the thermal stability of the composites is considerably affected by the pH of the reaction medium, its influence on the surface morphology is very small. Independently, of the synthetic conditions, the electrochemical properties were better for PEDOT/Al2O3 than for pure PEDOT, reflecting that alumina particles promote the charge mobility. The highest specific capacitance (SC; 141 F/g), which was 55% higher than that obtained for pure PEDOT, was achieved for the composite prepared at pH¿=¿8.8 using a 4:1 monomer:alumina ratio. These conditions favor the participation of OH– groups as secondary doping agents without degrading the polymer matrix and enhance the specific surface of the films, facilitating the ionic mobility. On the other hand, application of a multi-step polymerization strategy has shown that interfaces originated by consecutive steps enhance the SC.
Gloss is a critical issue in many applications in the coating industry. Gloss depends on optical and rheological properties of complex mixtures, and estimating gloss from basic properties is still a challenge. In order to predict the gloss of an industrial thickened-to-application formulation this work presents a gloss-rheology semi empirical-modeling approach based on a gloss excess function and previous work from other authors. A new matt (low gloss) hybrid waterborne polyurethane dispersion composed out of a self-matting agent (A) and a traditional silica-based matting agent (B) has been studied, and the resulting gloss of the mixture has been correlated to pure component gloss values and dynamic viscosity at medium shear rate. Several modeling options have been tested and their goodness of fit has been determined. The most promising options have been selected and validated towards untrained data sets.
Actualmente en España, las centrales nucleares están acumulando el combustible nuclear gastado (CNG) y apenas disponen de espacio suficiente para seguir almacenando el residuo generado por la actividad de la central. En consecuencia, es necesario adoptar una solución definitiva a la gestión de los residuos nucleares. La opción aceptada internacionalmente para almacenar definitivamente el CNG como la más segura y viable es el Almacenamiento Geológico Profundo (AGP) basado en el confinamiento y la protección del residuo mediante un sistema de multibarrera. Dicho sistema considera el CNG como primera barrera donde están contenidos los radionúclidos (RN) debido a las propiedades físicas y químicas del propio combustible.Con el objetivo de evaluar la seguridad del AGP y determinar el comportamiento del CNG en condiciones relevantes para su almacenamiento definitivo, en el presente trabajo se han planteado cuatro posibles escenarios que podrían provocar la alteración del combustible. Dichos escenarios se han estudiado mediante análogos no irradiados del CNG.En el proceso de alteración de las barreras que componen el AGP, la corrosión anaeróbica de la capsula metálica produce una elevada presión de hidrógeno que podría entrar en contacto con el CNG. A su vez, la entrada de agua en el repositorio y la temperatura a la que se encuentra el CNG podrían hacer aumentar la humedad en las proximidades del residuo. Por lo tanto, en este trabajo se ha estudiado el efecto del vapor de agua en contacto con el UO2 en atmósfera de H2. Los resultados obtenidos muestran que se produce la oxidación del uranio tanto en condiciones anaeróbicas como en condiciones reductoras en función de la temperatura usada. Por otro lado, en presencia de nanopartículas de paladio, análogas a las partículas épsilon del CNG, no se observó oxidación alguna del UO2 en presencia de H2.En el momento en que el agua entre en contacto con el CNG, los RN segregados de la matriz más volátiles y solubles serán lixiviados de forma prácticamente instantánea (IRF) provocando un aumento significativo de radiación en las aguas subterráneas. Con el objetivo de predecir la liberación de dichos RN se ha diseñado un modelo y un algoritmo matemático que ha permitido predecir la liberación de los RN disueltos en la matriz e identificar y cuantificar los RN que forman parte de la IRF de un combustible real. Los resultados obtenidos de la aplicación del modelo concuerdan con resultados experimentales publicados anteriormente. Por lo tanto, se puede concluir que el modelo y el algoritmo cumplen con los objetivos marcados de identificación, predicción y cuantificación de la distribución de los RN en el CNG.Debido a que los mecanismos de alteración del UO2 podrían variar dependiendo de la composición del agua subterránea, se ha estudiado la corrosión del CNG en contacto con aguas de cemento. Para ello se ha usado un electrodo de SIMFUEL con el que se han realizado ciclovoltamogramas, experimentos potenciostáticos y mediciones del potencial de corrosión en condiciones hiperalcalinas y en presencia de calcio y silicato como símil de aguas de cemento. Los resultados muestran una disminución de la corrosión en presencia de calcio y silicato que podría ser provocada por la precipitación de fases sólidas en la superficie del SIMFUEL o por la estabilización de las fases reducidas.Por último, la precipitación de fases sólidas podría ayudar a reducir la concentración de los RN liberados por el CNG. En este contexto, se han estudiado y determinado las capacidades de retención de dos fases sólidas de uranio; la soddiita y la uranofana, en contacto con Cs y Sr en disolución. Se ha determinado que ambos sólidos son capaces de adsorber ambos iones en su superficie, siendo la soddiita el sólido con mayor capacidad de retener Cs y la uranofana la fase sólida con mayor capacidad de retención de Sr. Por tanto, la formación de estas fases podría disminuir la concentración de estos RN liberados a la geosfera.
Nanoscale Zero Valent Iron (nZVI) represents a promising material for subsurface water remediation technology. However, dry, bare nZVI particles are highly reactive, being pyrophoric when they are in contact with air. The current trends of nZVI manufacturing lead to the surface passivation of dry nZVI particles with a thin oxide layer, which entails a decrease in their reactivity. In this work an activation procedure to recover the reactivity of air-stable nZVI particles is presented. The method consists of exposing nZVI to water for 36 h just before the reaction with the pollutants. To assess the increase in nZVI reactivity based on the activation procedure, three types of nZVI particles with different oxide shell thicknesses have been tested for Cr(VI) removal. The two types of air-stable nZVI particles with an oxide shell thickness of around 3.4 and 6.5 nm increased their reactivity by a factor of 4.7 and 3.4 after activation, respectively. However, the pyrophoric nZVI particles displayed no significant improvement in reactivity. The improvement in reactivity is related mainly to the degradation of the oxide shell, which enhances electron transfer and leads secondarily to an increase in the specific surface area of the nZVI after the activation process. In order to validate the activation process, additional tests with selected chlorinated compounds demonstrated an increase in the degradation rate by activated nZVI particles.
Carbon capture and storage (CCS) and carbon capture and utilisation (CCU) are acknowledged as important R&D priorities to achieve environmental goals set for next decades. This work studies biomass-based energy supply chains with CO2 capture and utilisation. The problem is formulated as a mixed-integer linear program. This study presents a flexible supply chain superstructure to answer issues on economic and environmental benefits achievable by integrating biomass-coal plants, CO2 capture and utilisation plants; i.e. location of intermediate steps, fraction of CO2 emissions captured per plant, CO2 utilisation plants' size, among others. Moreover, eventual incentives and environmental revenues will be discussed to make an economically feasible project. A large-size case study located in Spain will be presented to highlight the proposed approach. Two key scenarios are envisaged: (i) Biomass, capture or utilisation of CO2 are not contemplated; (ii) Biomass, capture and CO2 utilisation are all considered. Finally, concluding remarks are drawn.
ABA triblock copolyesters were synthesized by ring-opening polymerization (ROP) of l-lactide in solution initiated by a telechelic d-glucose-based polyester macroinitiator. The macroinitiator with a number-average molecular weight about 2500 g mol-1 was synthesized by non-stoichiometric polycondensation in the melt of 2,4:3,5-di-O-methylene-d-glucitol and dimethyl succinate. Two triblock copolyesters of Mn ranging between ~6000 and ~9000 g mol-1, and differing in the length of the polylactide blocks were prepared. These copolyesters started to decompose when heated at ~220 °C and degraded slowly upon aqueous incubation under physiological conditions. They did not display any perceivable crystallinity and showed a single glass transition temperature (Tg) around 60 °C with the higher value corresponding to the larger content in glucitol units. The copolyesters were able to form nanoparticles with average diameters of ~100–130 nm and satisfactory dispersity. The effect of the block lengths on size, ¿-potential values and physical stability of the nanoparticles was evaluated. A molecular dynamics simulation study allowed modelling the two-phase structure of the nanoparticles and evidenced the preference of the glucose-based block to be peripherally located.
At a global level, access to safe drinking water and sanitation has been monitored by the Joint Monitoring Programme (JMP) of WHO and UNICEF. The methods employed are based on analysis of data from household surveys and linear regression modelling of these results over time. However, there is evidence of non-linearity in the JMP data. In addition, the compositional nature of these data is not taken into consideration. This article seeks to address these two previous shortcomings in order to produce more accurate estimates.
We employed an isometric log-ratio transformation designed for compositional data. We applied linear and non-linear time regressions to both the original and the transformed data. Specifically, different modelling alternatives for non-linear trajectories were analysed, all of which are based on a generalized additive model (GAM).
Results and discussion
Non-linear methods, such as GAM, may be used for modelling non-linear trajectories in the JMP data. This projection method is particularly suited for data-rich countries. Moreover, the ilr transformation of compositional data is conceptually sound and fairly simple to implement. It helps improve the performance of both linear and non-linear regression models, specifically in the occurrence of extreme data points, i.e. when coverage rates are near either 0% or 100%.
Chemical pulp mills have a need to diversify their end-product portfolio due to the current changing bio-economy. In this study, the methane potential of brown, oxygen delignified and bleached pulp were evaluated in order to assess the potential of converting traditional fibers; as well as microcrystalline cellulose and filtrates; to energy. Results showed that high yields (380 mL CH4/gVS) were achieved with bleached fibers which correlates with the lower presence of lignin. Filtrates from the hydrolysis process on the other hand, had the lowest yields (253 mL CH4/gVS) due to the high amount of acid and lignin compounds that cause inhibition. Overall, substrates had a biodegradability above 50% which demonstrates that they can be subjected to efficient anaerobic digestion. An energy and cost estimation showed that the energy produced can be translated into a significant profit and that methane production can be a promising new alternative option for chemical pulp mills.
Hydrogenolysis of glycerol was studied using a diluted aqueous solution of glycerol in gas phase and atmospheric pressure on Ni/¿-Al2O3 catalyst. The catalytic transformation of glycerol generates products derived from dehydration, dehydrogenation, hydrogenolysis and condensation reactions. Deep hydrogenolysis route to produce CH4 prevails in the first few hours of reaction. As the reaction time progress, dehydration-dehydrogenation products start to appear. Here, a description of the deactivation sources and its effects on the catalytic performance of Ni catalyst was proposed. The catalyst was characterized before and after the catalytic reaction by high-resolution transmission electron microscopy (HRTEM) and by employing Fourier transformed infrared spectroscopy (FTIR) of adsorbed CO. A source of deactivation was due to carbonaceous deposition. FTIR at low CO dosing pressure reveal bands assignments species essentially due to linear and bridge carbonyls, whereas high pressure CO dosing produces a complex spectra due to polycarbonyls. X-ray absorption near edge structure (XANES) analysis was employed to reveal the initial degree of reduction of the fresh catalyst. The oxidation of metallic Ni in the course of reaction may also be considered as a source of deactivation. Ni oxide species promote dehydration routes. Alumina support facilitates nickel species to be more active toward interacting with glycerol. Dehydration, which takes place on the acid sites, is the mainly route related to the generation of carbon deposition and to the observed catalyst deactivation. Another source of deactivation was due to carbiding of Ni to form Ni3C. The regeneration of used Ni catalyst was achieved by oxidation-reduction steps at 723 K.
Srinivasan, S.; Fernandez, M.; Ramon, E.; Garriga, P. Biochimica et Biophysica Acta - Molecular Basis of Disease Vol. 1863, p. 1-8 DOI: 10.1016/j.bbadis.2017.05.006 Data de publicació: 2017-07-01 Article en revista
Deuteranopia is an X-linked congenital dichromatic condition in which single point mutations in green cone opsin lead to defective non-functional cone photoreceptor cells. Green cone opsin belongs to the G protein-coupled receptor superfamily and consists of a seven transmembrane helical apoprotein covalently bound to 11-cis-retinal, by means of a protonated Schiff base linkage, in its inactive dark state. Several point mutations in green cone opsin have been reported to cause deuteranopia, but the structural details underlying the molecular mechanisms behind the malfunction of mutated opsins have not been clearly established. Here, deutan N94K and R330Q mutants were studied by introducing these substitutions into the native green cone opsin gene by site-directed mutagenesis. The mutant proteins were purified and analyzed using UV-vis spectroscopy and transducin activation assay. We find that the N94K mutant binds the retinal chromophore by means of an unprotonated Schiff base linkage in contrast to previous studies that reported no chromophore regeneration. The other mutant studied, R330Q, showed impaired functionality as measured by its reduced transducin activation ability when compared to wild-type green cone opsin. A double Cys mutant that could form a stabilizing disulfide bond was used in an attempt to address the instability of the green opsin mutants. Our results suggest the presence of key intramolecular networks which may be disrupted in deuteranopia, and these findings could help in finding therapeutic solutions for treating color blindness. Furthermore, our results can also have implications for the study of other visual pigments and other rhodopsin-like G protein-coupled receptors.
Aquesta tesi doctoral té la seva base en l'experiència professional amb malalts amb disfàgia orofaríngia. Aquesta síndrome clínic, de gran prevalença en l'entorn sanitari i social, d'etiologies molt diverses està sent sistemàticament infradiagnosticat i mal tractat. Això porta a unes taxes de morbiditat inacceptables. L'experiència adquirida amb els pacients tractats, conclouen en un estudi epidemiològic que permet arribar a unes conclusions.Es va detectar la necessitat d'un protocol orientat a la valoració de la deglució de risc, disfàgia orofaríngia.Tenint en compte els espessidors i gelatines alimentàries habitualment utilitzats per barrejar amb l'aigua i els aliments es va proposar iniciar una investigació en laboratori per determinar si el que àmpliament s'estava fent en hospitals, residències geriàtriques, centres educatius i domicilis era correcte o no. Aquest estudi es va realitzar a la Universitat Politècnica de Catalunya (UPC), utilitzant els espessidors habituals i un tipus de gelatina d'ús comú. Aquest estudi es va imposar com a objectiu comprovar si determinats productes recomanats per ser utilitzats en dietes destinades a persones afectades per disfàgia compleixen adequadament les funcions per a les que han estat dissenyats i elaborats, independentment de si són productes farmacèutics o, simplement, additius alimentaris. Els resultats obtinguts confirmen que els espessidors denominats de segona gamma compostos fonamentalment per gomes (xantana, guar...), presenten un comportament més segur, des del punt de vista sanitari, que els de primera gamma, constituïts sobretot per midó, modificat o no. S'han detectat diferències significatives relacionades amb el temps de repòs de la mostra i el percentatge de espessidor aplicat per aconseguir les consistències sanitàries: líquid fi, nèctar, mel i pudding. En concret es requereix un 6% de espessidor de 1a gamma per arribar el grau de consistència més alt, mentre que aquest valor només és un 2% en el espessidor de 2a gamma.Paraules clau: deglució, espessidor, viscositat, midó, goma, glucosa.
Sulfaquinoxaline (SQX) is an antimicrobial of the sulfonamides class. Usually employed in veterinary medicine, this contaminant of emerging concern has been found in superficial and groundwater and its consequences for the environment and human health are not completely known. In this study, SQX (C0 = 500 µg L-1, 1 L) degradation by an ozonation process at pH 3, 7, and 11 was evaluated. Ozonation was effective in degrading SQX: efficiency exceeding 99% was obtained applying an ozone dose of 2.8 mg L-1 at pH 3. Assays were performed according to a 22 design of experiments (DOE) with star points and three central points for statistical validity. Minimum and maximum levels were set at 3 and 11 for pH, and 0 and 11.5 mg L-1 for applied ozone dose. There was no significant interaction between these variables, and the pH value played the most important role in terms of contaminant degradation. In relation to toxicity, samples ozonated at pH 3 did not inhibit the luminescence of the bacteria, even though different intermediates were formed and identified by mass spectra. At pH 7, inhibition of luminescence remained almost constant (at around 30%) according to ozonation time or ozone dose. However, the hydroxyl radical, the major oxidant at pH 11, was responsible for the formation of toxic intermediates.
Wind turbines are generally considered cost-effective, reliable and sustainable energy sources. Fires are not common in wind turbines, but a significant number of fires occur every year due to the large number of turbines installed. Wind turbine fires are difficult to extinguish hence significant damage is expected. Due to the unmanned operation, the probability of a turbine being occupied during a fire is very low. However, operators can do several tasks every week, and hence be exposed to a certain risk. Moreover, there is a general lack of information about how a fire develops inside a wind turbine and the subsequent evolution of the tenability conditions during the time required for an eventual evacuation. Gamesa has been working on fire safety since 2013, using CFD fire modelling to provide insights on wind turbine fire development for the design of emergency procedures. The paper describes a fire hazard analysis performed in a Gamesa’s 2.5 MW turbine. A CFD simulation is carried out to estimate the effects during the first minutes of a typical wind turbine fire in an electrical cabinet. Results show that average oxygen concentration at the nacelle remains above 19.5% during the first 10 min; temperature remains below 60°C for 12 min if measured at 1.5 m; and visibility is on average assured at heights lower than 1.5 m, with values above 5 m during the first 8 min in worse locations, implying no danger for personnel. The potential of this type of analysis to design safer wind turbines under performance-based approaches is clearly demonstrated.
Bin, R.; Cailloux, J.; Santana, O.; Bou, J. J.; Sanchez-Soto, M.; Odent, J.; Raquez, J.; Dubois, P.; Carrasco, F.; Maspoch, M. Journal of applied polymer science Vol. 134, p. 45367-45379 Data de publicació: 2017-06-14 Article en revista
Films of an architecturally modified poly(lactic acid) (PLAREx) with three different types of fumed silica nanofillers (SiO2) were processed through reactive extrusion-calendering in a pilot plant. The effects of the SiO2 type on both the dispersion and the crystallization behaviour under dynamic and isothermal conditions are investigated using transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The mechanical properties are assessed by tensile testing. TEM micrographs showed that the improved chemical affinity of both surface-treated SiO2 towards PLAREx end groups did not improve particle dispersion. DSC results revealed that untreated SiO2 nucleated PLAREx more efficiently than both surface-modified silicas. The activation energy for the isothermal crystallization process, as determined by an Arrhenius method, suggests that addition of untreated SiO2 enhances the crystallization rate of PLAREx. However, it seems that the tensile behaviour remained unchanged whether silicas were added or not.
En la industria de l'acabat de la pell s'utilitzen molts tipus de resines entre elles butadièniques, acríliques, uretàniques que ajudades per auxiliars com ara pigments, ceres tactes etc. donen lloc als diferents articles que actualment es comercialitzen.En aquest treball es tracta de caracteritzar un grup molt concret i a la vegada molt extens de resines; les resines acríliques. Es tracta de a partir un polímer base anar incorporant diferents grups funcionals, aquests grups funcionals donaran conformació a la resina acrílica i conseqüentment donaran propietats particulars a l'acabat de la pell. Es recull informació tant química com física de cada un dels monòmers.Finalment es realitzen una sèrie d'assajos comparatius entre les resines obtingudes per tal de veure les característiques particulars de cadascuna.Les tècniques utilitzades tant en la síntesi de les resines com posteriorment en la seva aplicació sobre pell estan considerades com no agressives al medi ja que es realitzen en medi aquós evitant així la utilització de solvents volàtilsL'objectiu d'aquest treball és la síntesi i caracterització de les resines acríliques a partir dels seus grups funcionals S'ha dividit en cinc parts1- Síntesi i caracterització de les resines acríliques a partir de monòmers funcionals. Saber en tot moment les característiques aportades per els grups funcionals de les cadenes laterals en l'acabat de la pell.2- Influència del tensioactiu en les característiques de la resina acrílica. En una resina sense grup funcional veure com influeix la quantitat de tensioactiu en el comportament de la resina acrílica.3- influència de la concentració de grup funcional en les resines sintetitzades. Saber quines característiques aporten els grups funcionals a la resina acrílica degut a la seva concentració.4- Veure com les resines acríliques sintetitzades responen davant l'acció de reticulants convencionals usats en la industria del cuir.5- Finalment com a última part, es busca una reacció de reticulació entre les resines sintetitzades aprofitant els grups funcionals utilitzats, utilitzant mètodes de reacció entre resines aprofitant els seus grups funcionals.Es treballaran una sèrie de monòmers acrílics, cadascun amb un grup funcional diferent. Les resines obtingudes s'aplicaran en l'acabat de la pell. L'estudi comprèn tant l'aplicació de la resina en la pell com algunes de les característiques dels films obtinguts. Es realitzarà una resina base a partir d'aquí s'aniran afegint els diferents monòmers i s'avaluaran els efectes sobre la resina original.Les resines obtingudes s'aplicaran sobre pell seguint tècniques normals de producció. Posteriorment, els acabats obtinguts s'avaluaran seguint els mètodes d'anàlisi destinats als acabats de la pell. Es realitzaran diferents assajos que segueixen normes reconegudes de forma internacional (flexions, adhesió de l'acabat, resistència a agents agressius)... a més d'una sèrie d'especificacions intrínseques de la pròpia resina (sòlids, pH, viscositat).L'objectiu d'aquest últim capítol es obtenir un acabat amb bones prestacions i bones solideses fent reaccionar dues resines funcionalitzades entre sí. D'aquesta manera es podria obtenir acabats reticulats però utilitzant resines reactives. Amb aquest sistema s'evita l'addició de productes que continguin substàncies restringides.
Bacteria-mediated diseases are a global healthcare concern due to the development and spread of antibiotic resistant strains. Cationic compounds are considered membrane active biocidal agents having a great potential to control bacterial infections, while limiting the emergence of drug resistance. Herein, the versatility and simplicity of the Layer-by- Layer (LbL) technique was used to functionalize polymer nanoparticles with antibacterial aminocellulose conjugate in a multilayer fashion. Stable polyelectrolyte-decorated particles with an average size of 250 nm and zeta potential of ± 40 mV were developed after five LbL assembly cycles. The antibacterial activity of these particles against Gram- positive Staphylococcus aureus and Gram-negative Escherichia coli increased significantly when the polycationic aminocellulose was applied as an uppermost layer. The large number of amino groups available on the particles surface improved the interaction with bacterial membrane phospholipids leading to membrane disturbance as was confirmed by Langmuir monolayer. The biopolymer decorated NPs were also able to inhibit the drug resistant biofilm formation, without affecting the human cells viability and therefore are promising alternatives for controlling bacterial infections occurrence.
The aim of this work is to present and test a novel approach to describe access to community drinking water points for planning purposes. The technical limits and possible benefits of including compositional population description based on service level into water and sanitation sector-related planning is illustrated with a simplified case example.
We report the synthesis of an amphiphilic block copolymer by e-ROP of ¿-pentadecalactone (PDL) initiated by poly(ethylene glycol) bis amine-ended as macroiniciator using Candida antarctica Lipase B (CALB) as catalyst.
The present communication describes the synthesis of triblock copolyesters made of a relatively hydrophilic block of
poly(glucitylene succinate) (PGluxSucc) attached to two dangling hydrophobic PLA blocks. The formation of nanospheres from
these copolyesters is then explored paying particular attention to the effect of the length of the blocks on their thermal properties, particle size, ¿-potential and physical stability. The experimental work is
supported by a modelling study carried out by molecular dynamics.
A supercritical biodiesel production process via transesterification of vegetable oil with methanol, using CO2 as co-solvent is designed, simulated, and validated with experimental data. A preliminary study of the liquid-vapor equilibrium of the reacting mixture at different compositions was done to determine the supercritical conditions, by means of pressure-temperature diagrams. Under supercritical conditions, the presence of a single phase increases the reaction kinetics, avoiding the limitation by interphase mass transfer, and enabling to carry out the process with low residence time. The proposed process is based on two fixed-bed catalytic reactors in series, with intermediate glycerol separation. CO2 used as co-solvent decreases the critical temperature, enabling to carry out the process in milder conditions. The intermediate glycerol separation displaces the chemical equilibrium towards higher conversion of triglyceride, increasing biodiesel yield. The results of a complete experimental study are used to validate the model, through a comparison with the simulations result.
Vera, M.; Martin-Alonso, J.; Mesa, J.; Granados, M.; Beltrán, J.; Casas, S.; Gibert, O.; Cortina, J. Chemical engineering journal Vol. 317, p. 961-971 DOI: 10.1016/j.cej.2017.02.081 Data de publicació: 2017-06-01 Article en revista
The decrease of water quantity and quality in water scarcity areas is palliated by improving water treatments with membrane technologies. System performance and efficiency, and then cost, is mainly affected by membrane fouling, which is still not well understood and controlled appropriately. In this study, the influence of content and composition of dissolved organic matter (DOM) on a membrane ultrafiltration (UF) stage from a full-scale UF stage in a drinking water treatment plant (DWTP) fed with surface water, groundwater (or blends of them) was investigated. Excitation-emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC) was used to characterize and assess DOM changes in water samples Water streams feeding the UF stage showed high variability in DOM content and composition. FEEM-PARAFAC analysis allowed the differentiation of seven different organic components. Additionally to the characterization and monitoring of DOM in the full-scale UF stage, a bench scale UF pilot was run to experimentally correlate the impact of water quality with membrane performance. The experiments included testing synthetic solutions of model foulants (synthetic humic acid and bovine serum albumin) and blends of complex waters. To quantify fouling, the total fouling index (TFI) and the hydraulically irreversible fouling index (HIFI) were calculated for each filtration run. According to the results obtained, the correlation plots between the PARAFAC components and the fouling indices pointed at microbial byproducts (C1) and humic-like components (C2, C4, C5) as the ones showing higher correlations.
This paper analyses the 2016 environmental benchmark performance of the port sector, based on a wide representation of EcoPorts members. This is the fifth time that this study has been conducted as an initiative of the European Sea Ports Organisation (ESPO). The data and results are derived from the Self-Diagnosis Method (SDM), a concise checklist against which port managers can self-assess the environmental management of their port in relation to the performance of the EcoPorts membership. The SDM tool was developed in the framework of the ECOPORTS project (2002–2005) and it is managed by ESPO. A total number of 91 ports from 20 different European Maritime States contributed to this evaluation. The main results are that air quality remains as the top environmental priority of the respondent ports, followed by energy consumption and noise.
In terms of environmental management, the study confirms that key components are commonly implemented in the majority of European ports. 94% of contributing ports have a designated environmental manager, 92% own an environmental policy and 82% implement an environmental monitoring program. Waste is identified as the most monitored issue in ports (80%), followed by energy consumption (73%) and water quality (70%)
We report the simple and fast fabrication of a bioactive integrated platform based on poly(3,4-ethylenedioxythiophene) and ¿-poly(glutamic acid)-cystamine hydrogel for the simultaneous delivery and electrochemical detection of dopamine. As shown in Figure 1, the different steps involved in the development of bioactive integrated platform consist of (i) anodic polymerization of 3,4-ethylenedioxythiophene on screen printed carbon electrodes, (ii) synthesis of biodegradable hydrogel in an aqueous environment on the surface of poly(3,4-ethylenedioxythiophene) film and gelatin which act as an anchor point, (iii) incorporation of dopamine into hydrogel by immersing method in acidic medium and finally (iv) release and electrochemical detection of dopamine in physiological buffer commonly used in biological research. The preliminary findings suggest that dopamine release rates from ¿-poly(glutamic acid)-cystamine hydrogels were dependent on the molecular weight of ¿-poly(glutamic acid), the cross-linking degree of the hydrogels, pH and ionic strength of the medium. On the other hand, the electrochemical assays indicate that we have successfully obtained high sensitive sensors (8·10-5 mA/µM dopamine) with a lower limit detection (0.45 µM).
Figure 1. Schematic representation of the different steps involved in the development of bioactive platform for the simultaneous drug delivery and electrochemical detection.
Fabregat, G.; Osorio, J.; Castedo, A.; Armelin, E.; Buendía, J.; Llorca, J.; Aleman, C. International Symposium Frontiers in Polymer Science Data de presentació: 2017-05-18 Presentació treball a congrés
We have fabricated potentially generalizable sensors based on polymeric-modified electrodes for the electrochemical detection of dopamine. Sensitive and selective sensors have been successfully obtained by applying a cold-plasma treatment during 1-2 minutes not only to conducting polymers (Figure 1) but also to electrochemically inert plastics, such as polyethylene, polypropylene, polyvinylpyrrolidone, poly(4-vinylphenol), polycaprolactone and polystyrene. The effects of the plasma in the electrode surface activation, which is an essential requirement for the dopamine detection when inert plastics are used, have been extensively investigated using X-ray photoelectron spectroscopy. Results clearly indicate that exposure of polymer-modified electrodes to cold-plasma produces the formation of a large variety of reactive species adsorbed on the electrode surface, which catalyse the dopamine oxidation promoting its detection. With this technology, which is based on the application of a very simple physical treatment rather than on the sophisticated chemical methods typically employed (e.g. functionalization, incorporation of catalytic nanoparticles and processing of the nanocomposites), we have defined a paradox-based paradigm for the fabrication of electrochemical sensors by using inert and cheap plastics.
Figure 1. SEM micrographs of (a) PEDOT and (b) PNCPy before (left) and after (right) plasma treatment using tcp= 2 min.
Figure 2. Control voltammogram of 10 ¿M DA in 0.1 M PBS at (a) polypropylene-, (b) polyvinylpyrrolidone-, (c) polycaprolactone- and (d) polystyrene-modified GCE.
Poly(1,4-disubstituted 1,2,3-triazoles) made by copper-catalyzed azide-alkyne cycloaddition form strongly bonded interfaces with several metal substrates. In this work, a variety of alkyne and azide monomers were explored as precursors to anticorrosion coatings for a standard high-strength aluminum-copper alloy (tradename AA2024). Monomers of comparatively low functionality (diazide and trialkyne) were found to act as superior barriers for electrolyte transfer to the aluminum surface. These materials showed excellent resistance to corrosive pitting due to the combination of three complementary properties: good formation of highly crosslinked films, as observed by FTIR and DSC; good adhesion to the aluminum alloy substrate, as shown by pull-off testing; and excellent impermeability, demonstrated by electrochemical impedance spectroscopy (EIS).
The best result was obtained with 1A21B3 polymer (Fig. 1), which has an azide monomer with six methylene groups and one alkyne with triazine aromatic ring. This composition helped moderate the degree of crosslinking among polymer chains, offering a beneficial flexibility to the polymer film (Fig. 2A). Thus, the presence of bi-azide (A2) and tri-alkyne (B3) functionalities in poly(1,4-disubstituted 1,2,3-triazoles) coating has fulfilled the expected role by offering improved adhesion to the metal substrate and protective barrier properties at the film surface simultaneously (Figs. 2B-C).
Figure 1. Molecular formulas of azide (1A2) and alkyne (1B3) with schematic representation of hyperbranched poly(1,4-disubstituted 1,2,3-triazole).
Figure 2. A) Polytriazole 1A21B3 fabricated as flexible thin film, B) Pull-off adhesion values (*obtained from literature), and C) Corrosion potential evolution in NaCl 0.05M.
Reference: Armelin et. al ACS Applied Materials & Interfaces 2017, 9, 4231-4243.
Franco, M.; Simiand, E.; Diaz, A.; Katsarava, R.; del Valle, LJ.; Puiggali, J. International Symposium Frontiers in Polymer Science p. P1.080 Data de presentació: 2017-05-17 Presentació treball a congrés
The development of new materials in the field of biomedicine is an area of knowledge in continuous research. However, one of the major problems associated with materials and devices used in reparative and regenerative medicine are the bacterial infections that do not respond to conventional antibiotics. In this sense, the preparation of new materials which avoid these infections represents an advance in the development of biomaterials. On the other hand, the abuse of antibiotics has generated a growing problem of bacterial resistance to these drugs. An alternative to the antibiotic treatment could be the phage therapy, which uses the bacteriophages (bacteria-specific viruses) to treat pathogenic bacterial infections.
In this work, the incorporation of bacteriophages in hydrogel scaffolds has been studied. Biodegradable hydrogels were obtained from nanofibers of poly(¿-glutamic acid) (PGGA).
PGGA nanofibers were prepared from polymer solutions in trifluoroacetic acid by using the electrospinning technique. In order to obtain appropriate fibers different parameters such as solvent, dissolution time, polymer concentration and flux were optimized. The obtained nanofibers were analyzed by scanning electron microscopy (SEM) to determine their morphology and diameter. These nanofibers were then crosslinked and hydrated in aqueous medium to form a stable hydrogel (Figure 1). The different hydrogels were characterized according to fiber diameter, swelling rate, thermal properties, solubility, and degradability.
Finally, these hydrogels were loaded during hydration with specific bacteriophages against the bacterium Staphylococcus aureus, demonstrating that these bacteriophages can be absorbed into the PGGA fibers keeping their biological activity (Figure 2). The development of these new matrices means a promising advance for their use as biomedical material for the control of bacterial infections.
Figure 1.Crosslinking reaction of PGGA nanofibers. SEM images of PGGA nanofibers before (left) and after crosslinking (right). Increasing the degree of crosslinking causes an increase in the diameter of the hydrogel fibers.
Figure 2. TEM image showing the morphology of the bacteriophage recovered from the hydrogel (left). Inhibition of Staphylococcus aureus bacteria growth in presence of the hydrogels of PGGA nanofibers (with 50% crosslinking) loaded with bacteriophages (right).
Acknowledgments: The authors acknowledge support from MINECO and FEDER (MAT2015-69547-R), and the Generalitat de Catalunya (2014SGR188).
Electrospinning of a segmented copolymer having polyglycolide hard segments has been successfully performed from polymer solutions diluted in 1,1,1,6,6,6-hexafluoroisopropanol. Continuous and uniform nanofibers with an average diameter of 500 nm and a smooth texture were attained using voltage, flow rate and needle-collector distance of 25 kV, 3.5 mL/h and 12 cm, respectively. A bactericide agent such as chlorhexidine (CHX) was also effectively loaded during the electrospinning process, rendering nanofibers with smaller diameter due the change of the conductivity of the solution (Figure 1). A bimodal diameter distribution was achieved, being 150 and 320 nm the mean diameters of the two populations. Electrospun nanofibers were highly crystalline as revealed by FTIR and DSC measurements. Incorporation of CHX had not a significant influence on crystallinity since the expected negative effect could be compensated by the higher polymer orientation attained in the stretched nanofibers.
New fabrics based on the molding of alternate layers of poly(¿-caprolactone) (PCL) films and the electrospun scaffolds of the segmented copolymer were prepared (Figure 2) and characterized. The thermal molding process rendered a PCL matrix reinforced homogeneously with nanofibers that could compensate the loss of mechanical properties when CXH was incorporated. Specifically, the incorporation of nanofibers increased the Young modulus from 180 MPa to 235 MPa and the maximum stress from 8 to 23 MPa.
Drug release experiments revealed that the multilayered system was able to guarantee a fast release of CHX when it was loaded in the outer PCL layers. On the other hand a delayed delivery was achieved when CHX was loaded into the nanofibers due to the good interactions that could be established between the drug and the hydrophilic polyglycolide component. This tunable release behaviour appears highly interesting to get a short and long term bactericide effect as demonstrated by growth inhibition and cell adhesion experiments.
Acknowledgments: The authors acknowledge support from MINECO and FEDER (MAT2015-69547-R), and the Generalitat de Catalunya (2014SGR188).
Dielectric spectroscopy measures the dielectric properties of a medium as a function of frequency.
Beginning in the 1970s, research electrochemists and materials scientists began to discover the power of
Electrochemical Impedance Spectroscopy (EIS) as a tool for studying difficult and complicated systems.
Currently the EIS technique is much more accessible and widely used in research areas beyond the world
of electrochemistry. It requires an impedance analyser with frequency range from 106Hz to 10-2Hz
equipped with appropriate software. The development of modern technique of Broadband Dielectric
Spectroscopy (BDS), during the mid-nineties, with extremely wide frequency range (1012 Hz to 10-6 Hz)
allowed the study of molecular fluctuations and collective phenomena, charge and polarization effects in
amorphous, semi-crystalline, liquid crystalline polymers as well as in polymer composites.
In the present work, some examples of a variety of polymeric materials (Fig. 1), characterized with EIS at
Innovation in Materials and Molecular Engineering Group (IMEM’s Group), will be showed.
The characterization of electrical properties with impedance spectroscopy requires the interpretation of
the data with the help of suitable models, which are divided into two broad categories: equivalent circuit
models and process models. From Nyquist, Bode and permittivity plots (Figs. 2A-C) it is possible extract
quantitative parameters related to the polymer resistance, capacitance, conductivity, relative permittivity,
using the electrical equivalent circuit (EEC, Fig. 2D). Additionally, qualitative observations regarding
blistering formation under coating or permeability of organic coatings can be performed. Results can vary
depending on types of polymers, film thickness, number of polymer layers; and the nature and surface
treatment of the metal substrate used as working electrode.
The versatility of dielectric spectroscopy has made it to become a fundamental tool in multidisciplinary
design, characterization and application of advanced functional materials and systems applied in such
diverse fields as those ranging from nanotechnology to biology.
References: 1) Müller et. al, J. Phys. Chem. B, 118 (2014) 1102-1112.2) González et. al, Eur. Polym. J.,
75 (2015) 210–222. 3) Dalmoro et. al, Prog. .Org. Coat. 88 (2015) 181–190. 4) Pérez-Madrigal et al., ACS
Appl. Mater. Interfaces, 7 (2015) 1632-1643.
Casanovas, A.; J. Divins, N.; Rejas, A.; Bosch, R.; Llorca, J. International journal of hydrogen energy Vol. 42, num. 19, p. 13681-13690 DOI: 10.1016/j.ijhydene.2016.11.197 Data de publicació: 2017-05-11 Article en revista
Ethanol steam reforming with pure ethanol and commercial bioethanol (S/C = 3) was carried out inside the housing of the exhaust gas pipe of a gasoline internal combustion engine (ICE) by using exhaust heat (610–620 °C). Various catalytic honeycombs loaded with potassium-promoted cobalt hydrotalcite and with ceria-based rhodium–palladium catalysts were tested under different reactant loads. The hydrogen yield obtained over the cobalt-based catalytic honeycomb at low load (F/W < 25 mLliq·gcat-1·h-1, GHSV = 4·102 h-1) was remarkably high, whereas that obtained over the noble metal-based catalytic honeycombs was much superior at high loads (F/W = 25–150 mLliq·gcat-1·h-1, GHSV = 4·102–2.4·103 h-1). At higher reactant loads the overall hydrogen production was limited by heat transfer from the exhaust heat to the reformer inside the housing of the exhaust gas pipe of the ICE. Extensive carbon deposition occurred over the cobalt-based honeycomb, making its use impractical. In contrast, stability runs (>200 h) at high load (F/W = 150 mLliq·gcat-1·h-1, GHSV = 2.4·103 h-1) showed that promotion of the ceria-supported noble metal catalyst with alumina and zirconia is a key element for practical application using commercial bioethanol. HRTEM analysis of post mortem honeycombs loaded with RhPd/Ce0.5Zr0.5O2–Al2O3 showed no carbon formation and no metal agglomeration.
In recent times there have been increasing efforts to integrate technology into wildfire management, especially in the fields of tactical monitoring and simulation. On the one hand, thermal infrared imaging (TIR) systems have been installed aboard surveillance aircraft including unmanned systems (UAS). On the other, there exists a variety of models and simulators able to forecast the fire spread. However, both fields currently present significant limitations. While relevant information is still extracted manually from aerial thermal imagery and is most times merely qualitative, simulators’ accuracy on fire spread prediction has proved insufficient. To solve these issues, this article presents a twofold methodology to couple meaningful automated wildfire monitoring with accurate fire spread forecasting. The main goals are to, firstly, automatically process aerial TIR imagery so that valuable information can be produced in real time during the event and, secondly, use this information to adjust a Rothermel-based simulator in order to improve its accuracy on-line. The fire perimeter location is tracked automatically through an unsupervised edge detector. Afterwards, an assimilation module uses the remotely sensed data to optimise the simulator's fuel and wind parameters, which are assumed to remain constant for a certain period of time. Subsequently, the optimum parameters’ values are used to issue a fire evolution forecast. All outputs are projected onto the corresponding Digital Terrain Model (DTM) and integrated into a Geographic Information System (GIS) for visualization. The global system was validated using two large-scale experiments. If these algorithms can be applied to a sufficiently rich and varied set of experimental data and further developed to cope with more complex scenarios, they could eventually be incorporated into a fire management decision support system.
Health-care associated infections (HAIs), or infections acquired in health-care facilities, affect hundreds of millions of patients worldwide each year. They are a major financial issue for the European healthcare system and were recognised as a global threat associated with medical care. The alarming statistics show that 1 in 10 patients develop infection in the hospital. About 400 000 of the HAIs are caused by antibiotic-resistant strains, estimated to cause economic loss in Europe of more than €1.5 billion.
Microbial biofilms are the reason for 80% of all infections currently treated in the hospitals. When established on catheters, heart valves, implants, and intrauterine devices the biofilms usually cause severe chronic infection, as well as systemic dissemination of the pathogen and dysfunction of the device. Catheter-associated urinary tract infections (CAUTIs) are the most frequent HAI worldwide that account for over 40% of all nosocomial infections and form 80% of all urinary tract infections in the hospitals. They are global health issue that delays the patient’s recovery and significantly increases healthcare costs, length of antibiotic therapy and risk of resistance development.
Microbiologically unsafe water is among the major causes of preventable morbidity and mortality. The World Health Organisation (WHO) reports that by 2025 half of the world’s population will be living in water scarcity areas with access only to inadequate drinking water leading to bacteria waterborne diseases such as diarrhea, cholera, dysentery and typhoid fever. Annually 2.2 million diarrheal disease deaths are being linked with the consumption of contaminated water. The extreme rainfall and flooding, as a result of the global warming, contribute to the microbial proliferation in surface and groundwater.
Antibiotic resistance is a worldwide problem. The emergence of antibiotic resistant bacteria is one of the most serious health threats nowadays. Efforts to prevent such threat are based on infection control in hospital and public settings and prevention of person-to-person spread. As a part of the public health strategy against the microbial infections, PROTECT will develop a versatile platform of 3 pre-commercial lines for production of antimicrobial textiles for hospitals and public areas, and anti-biofilm medical devices and water treatment membranes. These production lines will share as a common feature the use of high intensity ultrasound (US) in 3 different machinery designs: continuous roll-to-roll (R2R) US coating; continuous R2R spray coating with US nozzles, and batch mode (non-continuous) US coating.
Manich, A.M.; Cuadros Domènech, S.; Font Vallès, Joaquim; Bacardit, A.; Combalia, F.; Marsal , A. Journal of the American Leather Chemists Association Vol. 112, num. 5, p. 168-179 Data de publicació: 2017-05-08 Article en revista
Given the carcinogenic character of formaldehyde, it should be reliably determined in any substrate . The EN ISO 17226 Standard is the Official Method to quantify formaldehyde in leather. However, sorne misunderstandings may arise from the practica! conditions given by the Standard for the extraction of formaldehyde. Two agitation methods (magnetic agitation and reciproca! linear agitation), which fulfill the conditions of the Standard, have been used for the extraction of formaldehyde in twenty two samples of wet-blue split leather treated with resins synthesized with formaldehyde and with/without the addition of vegetable compounds. The agitation method influences the formaldehyde content and differences between the agitation methods depend on the formaldehyde resins and vegetable compounds applied. Magnetic agitation leads to formaldehyde contents that are 26% greater than those obtained when the reciproca! linear agitation method is used. Major brands specify allowable limits for formaldehyde content, which depend on the user (adult or babies) and whether the article is i n direct contact with t he skin. A high percentage of disagreement (33.3%) has been observed between the agitation methods in fulfilling the allowable limits. One-third of the formaldehyde content results that fulfilled the allowable limits with the reciproca! linear agitation method failed when the magnetic method was applied . The situation u rges the clarification of the shaking method in the EN ISO 17226 Standard to avoid the high leve! of contradictory results between methods that meet the agitation conditions of the Standard.
Perez, S.; Pashkuleva, I.; Gedanken, A.; Vidal, F.; Wey, M.; Sousa, R.A.; Tzanov, T. European & Global Summit for Clinical Nanomedicine and Targeted Medicine p. 200-201 Data de presentació: 2017-05-08 Presentació treball a congrés
A series of ionic complexes with a comb-like architecture and a nearly stoichiometric composition were prepared from bacterial poly(gamma,dl-glutamic acid) (PGGA) and alkyltrimethyl phosphonium bromides (nATMP·Br) bearing long linear alkyl chains with even numbers of carbon atoms (n) ranging from 12 to 22. The nATMP·PGGA complexes were non-water soluble but readily soluble in organic solvents, and they displayed a high thermal stability. Combined DSC and XRD studies revealed that these complexes adopted an amphiphilic layered structure with the polypeptide chain and the alkyl chain separated in two differentiated phases with a nanoperiodicity that increased steadily with the length of the alkyl chain. The paraffinic phase was found to be partially crystallized in an extent that decreased with n, so that complexes with n = 12 and 14 did not show any sign of crystallinity whereas those with n from 16 to 22 showed crystalline melting in the ~30–70 °C range. The structural transitions taking place by temperature effects were characterized by simultaneous SAXS/WAXS using synchrotron radiation at real time. In all cases, a shortening of the layer periodicity occurred upon heating with recovering of the initial structure after cooling. nATMP·PGGA with n = 16 showed strong antimicrobial activity against both E. coli and S. aureus, a property that could be related to the weak dissociation of the complexes happening upon incubation in water. The structure and properties of these complexes where comparatively discussed taking as reference their analog complexes made from PGGA and alkyltrimethylammonium bromides already studied by us.
Hermassi, M.; Valderrama, C.; Gibert, O.; Moreno Palmerola, Natàlia; Querol , X.; Harrouch, N.; Cortina, J. Science of the total environment Vol. 599-600, p. 422-430 DOI: 10.1016/j.scitotenv.2017.04.140 Data de publicació: 2017-05-05 Article en revista
Here, an alternative nutrient (N-P-K) recovery route from potassium-rich sludge anaerobic digestion side-streams using powder reactive sorbents (PRSs) is presented. In the first step, the optimum PRS system was determined in batch experiments with mixtures of: a) a sodium zeolite (NaP1) to facilitate the NH4+ and K+ sorption; b) a Ca-zeolite (CaP1) to facilitate the removal of P by formation of Ca-phosphates (e.g., CaHPO4(s)), and c) caustic magnesia containing mixtures of MgO to facilitate the formation of Mg/NH4/PO4 minerals (e.g., struvite and magnesium phosphates). Evaluation of the continuous and simultaneous N-P-K removal with mixtures of PRSs was carried out using a hybrid sorption/filtration system with ultrafiltration (UF) hollow-fibre membranes. The dosing ratios of the PRS mixtures were optimised on the basis of the equilibrium and kinetic sorption data, and a PRS dose (< 2–5 g PRS/L) was selected to ensure the hydraulic performance of the system. Under such conditions, and with synthetic anaerobic side-stream removal capacities (qt) of 220 ± 10 mg N-NH4/g, 35 ± 5 mg P-PO4/g, and 8 ± 2 mg K/g, removal efficiencies of 32 ± 3, 78 ± 5, and 26 ± 3% for ammonium, phosphate, and potassium, respectively, were obtained for the binary mixtures of NaP1/CaP1 zeolites. Contrary to the batch results, the use of tertiary mixtures of NaP1/CaP1/MgO only improved the K removal capacity and efficiency to 18 ± 2 mg K/g and 55 ± 4%, respectively, while the phosphate removal capacity and efficiency remained unchanged (ca. 35 ± 3 mg P-PO4/g; 80 ± 5%) and the ammonium capacity and efficiency were reduced to 185 ± 12 mg N-NH4/g and 20 ± 2%, respectively, due to the competing Mg2 + ion effect. Nutrient removal trials with real anaerobic side-streams using binary mixtures of Na/Ca zeolites showed a reduction of both the hydraulic performance and the nutrient removal ratios due to the presence of dissolved organic matter. However, constant removal ratios of N, P, and K were recorded throughout the filtration experiments. The loaded PRSs exhibited suitable nutrient release rates and bioavailability as co-substrates for soil quality improvement. Chemical analyses detected the formation of Ca/P/O and Mg/N/P/O neo-minerals; however, the mineralogical data revealed only the formation of struvite, even when no magnesium oxide was used.
Márquez, Y.; Cabral, T.; Lorenzetti, A.; Franco, M.; Turon, P.; del Valle, LJ.; Puiggali, J. Journal of applied polymer science Vol. 134, num. 44762 DOI: 10.1002/app.44762 Data de publicació: 2017-05-05 Article en revista
Luna, A.; Meng, L.; Díaz Aldana, N.; Graells, M.; Vasquez, J.; Guerrero, J. IEEE transactions on power electronics num. 99, p. 1-15 DOI: 10.1109/TPEL.2017.2700083 Data de publicació: 2017-05-02 Article en revista
Microgrids are energy systems that can work independently from the main grid in a stable and self-sustainable way. They rely on energy management systems to schedule optimally the distributed energy resources. Conventionally, the main research in this field is focused on scheduling problems applicable for specific case studies rather than in generic architectures that can deal with the uncertainties of the renewable energy sources. This paper contributes a design and experimental validation of an adaptable energy management system implemented in an online scheme, as well as an evaluation framework for quantitatively assess the enhancement attained by different online energy management strategies. The proposed architecture allows the interaction of measurement, forecasting and optimization modules, in which a generic generation-side mathematical problem is modeled, aiming to minimize operating costs and load disconnections. The whole energy management system has been tested experimentally in a test bench under both grid-connected and islanded mode. Also, its performance has been proved considering severe mismatches in forecast generation and load. Several experimental results have demonstrated the effectiveness of the proposed EMS, assessed by the corresponding average gap with respect to a selected benchmark strategy and ideal boundaries of the best and worst known solutions.
In this paper, the concept of environmental indicator is reviewed as a relevant element used in the environmental management of any organisation. The importance of this element within an Environmental Management System (EMS) is also justified. Although EMS standards recognise the relevance of using indicators, they do not specify any methodology to identify which indicators have to be implemented. In addition, the present research demonstrates that although there is a high percentage of European ports that have already implemented performance indicators, most of them do not mention the method applied to obtain the indicators. This suggests that some of the procedures used by ports to identify indicators may not necessarily be science-based or systematic in approach. For these reasons, the need to develop a new methodology able to identify the ports' most adequate indicators was detected. Therefore, a Tool for the identification and implementation of Environmental Indicators in Ports (TEIP) was developed. It aims at identifying performance indicators in ports and providing guidelines for their proper implementation. This is a computer and science-based tool (www.eports.cat/teip) that provides a quick calculation and outputs, and it is designed to be as user-friendly and practical as possible in order to facilitate its completion by the user. This new methodology is applicable to all types of ports no matter the size, geographical location or its commercial profile; it provides targeted and specific results for each one. TEIP aims at helping port managers at easily determining their significant port indicators, which provides valuable elements for the decision-making processes.
Martinez, A.; Serrano-Purroy, D.; Sureda, R.; Casas, I.; Pablo, J. Journal of nuclear materials Vol. 488, p. 302-313 DOI: 10.1016/j.jnucmat.2017.03.022 Data de publicació: 2017-05-01 Article en revista
The instant release fraction of a spent nuclear fuel is a matter of concern in the performance assessment of a deep geological repository since it increases the radiological risk. Corrosion studies of two different spent nuclear fuels were performed using bicarbonate water under oxidizing conditions to study their instant release fraction. From each fuel, cladded segments and powder samples obtained at different radial positions were used. The results were normalised using the specific surface area to permit a comparison between fuels and samples.
Different radionuclide dissolution patterns were studied in terms of water contact availability and radial distribution in the spent nuclear fuel.
The relationship between the results of this work and morphological parameters like the grain size or irradiation parameters such as the burn-up or the linear power density was studied in order to increase the understanding of the instant release fraction formation