Un nuevo modelo de cuantificación de la capacidad de pirólisis utilizando datos termogravimétricos aplicado a reprocesamiento de polímeros

Formulation of a new mathematical model, through the dimensional analysis methodology, to quantify the pyrolysis capacity of organic materials and thermoplastic polymers by means of the pyrolysis index is presented. The importance of this index is that it is possible to quantify the capacity of the polymer post-consumption or recycling to be pyrolyzed to obtain useful fuel fractions in the actual society. The new model is compared with three models of the literature, using non-isothermal (dynamic) thermogravimetric analysis data for the raw and reprocessed Polystyrene case study. This polymer is reprocessed five times in a single screw extruder. The raw and reprocessed polymer were characterized by proximate, elemental analysis and dynamic thermogravimetry under nitrogen atmosphere at four heating rates. A non-dimensional correlation was obtained to calculate the pyrolysis index as a function of the heating rate, characteristic temperatures, and conversion. It was found that the pyrolysis capacity increases with the heating rate and number of reprocessing in extrusion. In addition, the new model better fits the data to a linear trend between pyrolysis index with the heating rate and number of reprocessing.Se presenta la formulación de un nuevo modelo matemático, a través de la metodología de análisis dimensional, para cuantificar la capacidad de pirólisis de materiales orgánicos y polímeros termoplásticos por medio del índice de pirólisis. La importancia de este índice radica en que se puede cuantificar la capacidad que tiene polímero pos consumo o reciclado a ser pirolizado para la obtención de fracciones combustibles útiles en la actual sociedad. El nuevo modelo se compara con tres modelos de la literatura, a través de información del análisis termogravimétrico no isotérmico (dinámico) para el caso de estudio del Poliestireno virgen y reprocesado. Este polímero se reprocesa cinco veces en una extrusora monohusillo. El polímero virgen y reprocesado se caracterizaron por análisis próximo, elemental y termogravimetría dinámica en atmósfera de nitrógeno a cuatro velocidades de calentamiento. Se obtuvo una correlación adimensional para calcular el índice de pirólisis en función de la velocidad de calentamiento, temperaturas características, y conversión.  Se encontró que la capacidad de pirólisis aumenta con la velocidad de calentamiento y número de reprocesamientos en extrusión. Además, el nuevo modelo ajusta mejor los datos a una tendencia lineal entre el índice de pirólisis con la velocidad de calentamiento y número de reprocesamientos

The Debye’s model for the dielectric relaxation of liquid water and the role of cross-dipolar correlations. A MD-simulations study

By means of massive (more than 1.2 · 106 molecules) molecular dynamics simulations at 300 K we have disentangled self- and cross-dipolar contributions to the dielectric relaxation of liquid water that cannot be experimentally resolved. We have demonstrated that cross dipolar correlations are of paramount importance. They amount for almost a 60% of the total dielectric amplitude. The corresponding relaxation function is a one-step Debye-like function with a characteristic time, τcross, of the order of the phenomenological Debye time, τD. In contrast, the relaxation function corresponding to the self-contribution is rather complex and contains a fast decay related to dipolar librations and a second relaxation step that can be well described by two exponentials: a low-amplitude fast process (τ0 = 0.31 ps) and a main slow process (τself = 5.4 ps) that fully randomizes the dipolar orientation. In addition to dipolar relaxation functions, we have also calculated scattering-like magnitudes characterizing translation and rotation of water molecules. Although these processes can be considered as “jump” processes in the short time range, at the time scale of about τD–τcross, at which the cross-dipolar correlations decay to zero, the observed behavior cannot be distinguished from that corresponding to uncoupled Brownian translational and rotational diffusion. We propose that this is the reason why the Debye model, which does not consider intermolecular dipolar interactions, seems to work at time t ≳ τD.We acknowledge the Grant No. PID2021-123438NB-I00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe,” Grant No. TED2021-130107A-I00 funded by MCIN/AEI/10.13039/501100011033 and Unión Europea “NextGenerationEU/PRTR,” as well as financial support of Eusko Jaurlaritza, code: IT1566-22 and from the IKUR Strategy under the collaboration agreement between Ikerbasque Foundation and the Materials Physics Center on behalf of the Department of Education of the Basque Government

Insight into the Structure and Dynamics of Polymers by Neutron Scattering Combined with Atomistic Molecular Dynamics Simulations

Combining neutron scattering and fully atomistic molecular dynamics simulations allows unraveling structural and dynamical features of polymer melts at different length scales, mainly in the intermolecular and monomeric range. Here we present the methodology developed by us and the results of its application during the last years in a variety of polymers. This methodology is based on two pillars: (i) both techniques cover approximately the same length and time scales and (ii) the classical van Hove formalism allows easily calculating the magnitudes measured by neutron scattering from the simulated atomic trajectories. By direct comparison with experimental results, the simulated cell is validated. Thereafter, the information of the simulations can be exploited, calculating magnitudes that are experimentally inaccessible or extending the parameters range beyond the experimental capabilities. We show how detailed microscopic insight on structural features and dynamical processes of various kinds has been gained in polymeric systems with different degrees of complexity, and how intriguing questions as the collective behavior at intermediate length scales have been faced.This research was funded by the Basque Government, code: IT-1175-19 and the Ministerio de Economía y Competitividad code: PGC2018-094548-B-I00 (MCIU/AEI/FEDER, UE)

Nonwoven Mats Based on Segmented Biopolyurethanes Filled with MWCNT Prepared by Solution Blow Spinning

To prepare nonwoven mats constituted by submicrometric fibers of thermally responsive biopolyurethanes (TPU) modified with multiwalled carbon nanotubes (MWCNT), solution blow spinning (SBS) was used. The TPU was the product of synthesis using poly(butylene sebacate)diol, PBSD, ethyl ester L-lysine diisocyanate (LDI), and 1,3-propanediol (PD) (PBSe:LDI:PD) as reactants. TPU was modified by adding different amounts of MWCNT (0, 0.5, 1, 2, and 3 wt.%). The effect of the presence and amount of MWCNT on the morphology and structure of the materials was studied using field-emission scanning electron microscopy (FESEM) and Fourier-transform infrared spectroscopy (FTIR), respectively, while their influence on the thermal and electric behaviors was studied using differential scanning calorimetry (DSC) and capacitance measurements, respectively. The addition of MWCNT by SBS induced morphological changes in the fibrous materials, affecting the relative amount and size of submicrometric fibers and, therefore, the porosity. As the MWCNT content increased, the diameter of the fibers increased and their relative amount with respect to all morphological microfeatures increased, leading to a more compact microstructure with lower porosity. The highly porous fibrous morphology of TPU-based materials achieved by SBS allowed turning a hydrophilic material to a highly hydrophobic one. Percolation of MWCNT was attained between 2 and 3 wt.%, affecting not only the electric properties of the materials but also their thermal behavior.This research was funded by the Fondos de Investigación de Fco. Javier González Benito, política de reinversión de costes generales, Universidad Carlos III de Madrid [2012/00130/004], the Acción Estratégica en Acción Estratégica en Materiales nanocompuestos multifuncionales, Universidad Carlos III de Madrid [2011/00287/003], and the Project PID2020-112713RB-C22–C21 supported by AEI [Ministerio de Ciencia e Innovación of Spain], the University of the Basque Country (UPV/EHU) and (GIU18/216 Research Group)

The Corpus of Basque Simplified Texts (CBST)

In this paper we present the corpus of Basque simplified texts. This corpus compiles 227 original sentences of science popularisation domain and two simplified versions of each sentence. The simplified versions have been created following different approaches: the structural, by a court translator who considers easy-to-read guidelines and the intuitive, by a teacher based on her experience. The aim of this corpus is to make a comparative analysis of simplified text. To that end, we also present the annotation scheme we have created to annotate the corpus. The annotation scheme is divided into eight macro-operations: delete, merge, split, transformation, insert, reordering, no operation and other. These macro-operations can be classified into different operations. We also relate our work and results to other languages. This corpus will be used to corroborate the decisions taken and to improve the design of the automatic text simplification system for Basque.Cerrar texto de financiación Itziar Gonzalez-Dios's work was funded by a Ph.D. grant from the Basque Government and a postdoctoral grant for the new doctors from the Vice-rectory of Research of the University of the Basque Country (UPV/EHU). We are very grateful to the translator and teacher that simplified the texts. We also want to thank Dominique Brunato, Felice Dell'Orletta and Giulia Venturi for their help with the Italian annotation scheme and their suggestions when analysing the corpus and Oier Lopez de Lacalle for his help with the statistical analysis. We also want to express our gratitude to the anonymous reviewers for their comments and suggestions. This research was supported by the Basque Government (IT344-10), and the Spanish Ministry of Economy and Competitiveness, EXTRECM Project (TIN2013-46616-C2-1-R)

Disentangling Self-Atomic Motions in Polyisobutylene by Molecular Dynamics Simulations

We present fully atomistic molecular dynamics simulations on polyisobutylene (PIB) in a wide temperature range above the glass transition. The cell is validated by direct comparison of magnitudes computed from the simulation and measured by neutron scattering on protonated samples reported in previous works. Once the reliability of the simulation is assured, we exploit the information in the atomic trajectories to characterize the dynamics of the different kinds of atoms in PIB. All of them, including main-chain carbons, show a crossover from Gaussian to non-Gaussian behavior in the intermediate scattering function that can be described in terms of the anomalous jump diffusion model. The full characterization of the methyl-group hydrogen motions requires accounting for rotational motions. We show that the usually assumed statistically independence of rotational and segmental motions fails in this case. We apply the rotational rate distribution model to correlation functions calculated for the relative positions of methyl-group hydrogens with respect to the carbon atom at which they are linked. The contributions to the vibrational density of states are also discussed. We conclude that methyl-group rotations are coupled with the main-chain dynamics. Finally, we revise in the light of the simulations the hypothesis and conclusions made in previously reported neutron scattering investigations on protonated samples trying to address the origin of the dielectric β -process.This research was funded by the Basque Government, code: IT-1175-19 and the Ministerio de Economía y Competitividad code: PGC2018-094548-B-I00 (MCIU/AEI/FEDER, UE)

X-Ray Diffraction, Calorimetric and Dielectric Relaxation Study of the Amorphous and Smectic States of a Main Chain Liquid Crystalline Polymer

Los polímeros cristales líquidos (LCP) son sistemas complejos que forman mesofases que presentan orden orientacional y polímeros amorfos. Con frecuencia, el estado amorfo isotrópico no puede ser estudiado debido a la rápida formación de mesofases. En este trabajo se ha sintetizado y estudiado un nuevo LCP: poli(trietilenglicol metil p, p '-bibenzoato), PTEMeB. Este polímero presenta una formación de mesofase bastante lenta haciendo posible estudiar de forma independiente tanto los estados amorfo y de cristal líquidos. La estructura y las transiciones de fase del PTEMeB han sido investigados por calorimetría (DSC), con MAXS / WAXS con temperatura variable que emplean radiación de sincrotrón y con difracción de rayos X. Estos estudios han mostrado la existencia de dos transiciones vítreas, relacionadas con las fases amorfa y cristal líquido. Se ha realizado un estudio de relajación dieléctrica en amplios intervalos de temperatura y presión. Se ha encontrado que la transición vítrea dinámica de la fase amorfa es más lenta que la del cristal líquido. El estudio de la relajación ? nos ha permitido seguir la formación isoterma de la mesofase a presión atmosférica. Además, con el estudio el comportamiento dinámico a alta presión se ha encontrado que se produce la formación rápida de la mesofase inducida por cambios bruscos de presión. Liquid crystalline polymers (LCPs) are complex systems that include features of both orientationally ordered mesophases and amorphous polymers. Frequently, the isotropic amorphous state cannot be studied due to the rapid mesophase formation. Here, a new main chain LCP, poly(triethyleneglycol methyl p,p'-bibenzoate), PTEMeB, has been synthesized. It shows a rather slow mesophase formation making possible to study independently both the amorphous and the liquid crystalline states. The structure and phase transitions of PTEMeB have been investigated by calorimetry, variable-temperature MAXS/WAXS employing synchrotron radiation, and X-ray diffraction in oriented fibers. These experiments have pointed out the presence of two glass transitions, related to the amorphous or to the liquid crystal phases. Additionally, the mesophase seems to be a coexistence of orthogonal and tilted smectic phases. A dielectric relaxation study of PTEMeB over broad ranges of temperature and pressure has been performed. The dynamic glass transition turns out to be slower for the amorphous state than for the liquid crystal. Monitoring of the α relaxation has allowed us to follow the isothermal mesophase formation at atmospheric pressure. Additionally, the dynamical behavior at high pressures has pointed out the fast formation of the mesophase induced by sudden pressure changes

The Pharmacokinetics and interactions of ivermectin in humans—A mini-review

P. 42-46Ivermectin is an antiparasitic drug with a broad spectrum of activity, high efficacy as well as a wide margin of safety. Since 1987, this compound has a widespread use in veterinary medicine and it use has been extended in humans. Here we present a brief review of the information availabile regarding the pharmacokinetics and interactions of ivermectin in humans. Awareness of these characteristics could improve the clinical efficacy of Ivermectin. All Authors declare that they do not have any Conflict of interest and that the work is original. All Authors agree that the contents of the manuscript are confidential and will not be copyrighted, submitted, or published elsewhere (including the Internet), in any language, while acceptance by the Journal is under consideration.S

The pharmacokinetics and metabolism of ivermectin in domestic animal species

P. 25-37The pharmacokinetic properties of drugs are closely related to their pharmacological efficacy. The kinetics of ivermectin are characterised, in general terms, by a slow absorption process, a broad distribution in the organism, low metabolism, and slow excretion. The kinetics vary according to the route of administration, formulation, animal species, body condition, age, and physiological status, all of which contribute to differences in drug efficacy. Characterisation of ivermectin kinetics can be used to predict and optimise the value of the parasiticide effects and to design programmes for parasite control. This article reviews the pharmacokinetics of ivermectin in several domestic animal species.S

3D printing of customized all-starch tablets with combined release kinetics

[EN] Starch-based tablets with tailored releases were prepared by 3D printing using a hydrophobic drug. The importance of the origin of the excipient in the inks and tablets was analyzed. Besides, the effect of the geometry of the tablet on the drug release profile was also evaluated. The rheological properties of the inks was influenced by the botanic origin of the starch. Consequently, tablets presented different microporous structure and particular compression and swelling behaviors. Normal maize starch showed a non-well-defined porous morphology, not being able to form a stable structure whereas, waxy maize and potato starches exhibited a well-defined porous structure and were both able to maintain their integrity after long time immersion. Finally, tablets combining different starches and geometries were printed tailoring the drug release from 10 min to 6 h and designing two-steps profiles. The applicability of the developed 3D printed drug release systems in personalized therapies was demonstrated.Financial support from the University of the Basque Country (UPV/EHU) (GIU18/216 Research Group), from the Basque Government in the frame of Elkartek KK-2020/00053 and PIBA2020-1-0041 and from Spanish Ministry of Science and Innovation and Spanish State Research Agency (MCIN/AEI/10.13039/501100011033) in the frame of PID2019-105090RB-I00 project, are gratefully acknowledged. Moreover, we are grateful to the Macrobehavior-Mesostructure-Nanotechnology SGIker unit of the UPV/EHU. K. González thanks the University of the Basque Country for the grant “Contratación de doctores recientes hasta su integración en programas de formación postdoctoral en la UPV/EHU «DOKBERRI» 2020-I” (DOCREC20/07)