Methane hydrate: shifting the coexistence temperature to higher temperatures with an external electric field

In the present work, we used molecular dynamic simulations of the equilibrium NPT ensemble to examine the effect of an external electric field on the three-phase coexistence temperature of methane gas, liquid water and methane hydrate. For these simulations, we used the TIP4P/Ice rigid water model and a single-site model for methane. The simulations were implemented at two pressures, 400 and 250bar, over temperatures ranging from 285 to 320K and from 280 to 315K, respectively. The application of an external electric field in the range of 0.1-0.9caused the effect of the thermal vibrations of the water molecules to become attenuated. This resulted in a shift of the three-phase coexistence temperature to higher temperatures. Electric fields below this range did not cause a difference in the coexistence temperature, and electric fields above this range enhanced the thermal effect. The shift had a magnitude of 22.5K on average.Peer ReviewedPostprint (author's final draft

Mechanical recycling of plastic wastes. Case of study: high impact polystyrene for manufacturing TV components shelf

En este trabajo se presenta una introducción sobre la situación actual del reciclaje de los materiales plásticos a nivel mundial, con un especial interés en la situación en la que se encuentra el estado Europeo. A pesar de que existen numerosas técnicas de reciclado de plásticos, el método de reciclado mecánico ha llamado mucho la atención por parte de las industrias transformadoras del plástico debido a la capacidad de producción que puede llevarse a cabo mediante el uso de técnicas como la extrusión y la inyección de plásticos. La parte final de este trabajo se enfoca en un caso práctico que se llevó a cabo en el Centre Català del Plàstic (CCP) y la empresa SONY para la obtención de materiales plásticos reciclables para manufacturar carcasas de televisiones. El trabajo realizado en el CCP fue el estudio de la viabilidad de la sustitución de materiales vírgenes por materiales reciclados procedentes de residuos industriales. El estudio consistió en analizar la viabilidad de sustituir un poliestireno antichoque (HIPS) virgen por el mismo material de origen pero reciclado. De esta manera, se compararon las propiedades de cuatro materiales HIPS reciclados (HIPS-RA, -RB, -RC y -RD) así como un estudio de su morfología. Se observó que el índice de fluidez del HIPS aumentó con la proporción de material reciclado y con el número de procesos de transformación. La propiedad mecánica más afectada resultó ser la resistencia al impacto, y se observaron dos tipos de morfologías claramente diferentes. El material reciclado que mostró mejores propiedades fue el HIPS-RB, y fue escogido para sustituir al HIPS virgen en la producción de componentes de electrónica de consumo. Finalmente, el estudio realizado permitió analizar los factores que intervienen en el estudio de materiales reciclados, conocer las posibilidades de su aplicación en el caso concreto de componentes de electrónica de consumo y crear las bases para poder establecer una metodología para realizar futuros estudios de introducción de materiales reciclados en otras aplicaciones tecnológicas. Por lo anterior, el trabajo presenta una completa introducción en el área del reciclaje mecánico y las tendencias del mercado así como la viabilidad del reaprovechamiento de materiales de residuo para el desarrollo de componentes no estructurales y de elevada producción industrial.Postprint (published version

Tuning the Endocytosis Mechanism of Zr-Based Metal–Organic Frameworks through Linker Functionalization

A critical bottleneck for the use of metal-organic frameworks (MOFs) as drug delivery systems has been allowing them to reach their intracellular targets without being degraded in the acidic environment of the lysosomes. Cells take up particles by endocytosis through multiple biochemical pathways, and the fate of these particles depends on these routes of entry. Here, we show the effect of functional group incorporation into a series of Zr-based MOFs on their endocytosis mechanisms, allowing us to design an effi-cient drug delivery system. In particular, naphthalene-2,6-dicarboxylic acid and 4,4'-biphenyldicarboxylic acid ligands promote entry through the caveolin-pathway, allowing the particles to avoid lysosomal degradation and be delivered into the cytosol, en-hancing their therapeutic activity when loaded with drugs.C.A.O. thanks Becas Chile and the Cambridge Trust for funding. S.H. thanks the Cambridge Trust for funding. R.S.F. and D.F.-J. thank the Royal Society for the receipt of University Research Fellowships. D.F.-J. thanks financial support from ERC-2016-COG 726380. R.S.F., R.J.M., and I.A.L. thank the University of Glasgow and the EPSRC (EP/L004461/1) for funding. G.B., I.I., and D.M. acknowledge the financial support from 2014-SGR-80, MAT2015-65354-C2-1-R and EU FP7 ERC-Co 615954. ICN2 received support from the Spanish MINECO through the Severo Ochoa Centers of Excellence Program, under Grant No. SEV-2013-0295

Selective CO₂ capture in metal-organic frameworks with azine-functionalized pores generated by mechanosynthesis

Two new three-dimensional porous Zn(II)-based metal-organic frameworks, containing azine-functionalized pores, have been readily and quickly isolated via mechanosynthesis, by using a nonlinear dicarboxylate and linear N-donor ligands. The use of nonfunctionalized and methyl-functionalized N-donor ligands has led to the formation of frameworks with different topologies and metal-ligand connectivities and therefore different pore sizes and accessible volumes. Despite this, both metal-organic frameworks (MOFs) possess comparable BET surface areas and CO₂ uptakes at 273 and 298 K at 1 bar. The network with narrow and interconnected pores in three dimensions shows greater affinity for CO compared to the network with one-dimensional and relatively large pores-attributable to the more effective interactions with the azine groups

A robust binary supramolecular organic framework (SOF) with high CO2 adsorption and selectivity

A robust binary hydrogen-bonded supramolecular organic framework (SOF-7) has been synthesized by solvothermal reaction of 1,4-bis-(4-(3,5-dicyano-2,6 dipyridyl)dihydropyridyl)benzene (1) and 5,5’-bis-(azanediyl)-oxalyl-diisophthalic acid (2). Single crystal X-ray diffraction analysis shows that SOF-7 comprises 2 and 1,4-bis-(4-(3,5-dicyano-2,6-dipyridyl)pyridyl)benzene (3), the latter formed in situ from the oxidative dehydrogenation of 1. SOF-7 shows a three-dimensional four-fold interpenetrat-ed structure with complementary O−H···N hydrogen bonds to form channels that are decorated with cyano- and amide-groups. SOF-7 exhibits excellent thermal stability and sol-vent and moisture durability, as well as permanent porosity. The activated desolvated material SOF-7a shows high CO2 sorption capacity and selectivity compared with other po-rous organic materials assembled solely through hydrogen bonding

How reproducible are surface areas calculated from the BET equation?

Porosity and surface area analysis play a prominent role in modern materials science. At the heart of this sits the Brunauer-Emmett-Teller (BET) theory, which has been a remarkably successful contribution to the field of materials science. The BET method was developed in the 1930s for open surfaces but is now the most widely used metric for the estimation of surface areas of micro- and mesoporous materials. Despite its widespread use, the calculation of BET surface areas causes a spread in reported areas, resulting in reproducibility problems in both academia and industry. To prove this, for this analysis, 18 already-measured raw adsorption isotherms were provided to sixty-one labs, who were asked to calculate the corresponding BET areas. This round-robin exercise resulted in a wide range of values. Here, the reproducibility of BET area determination from identical isotherms is demonstrated to be a largely ignored issue, raising critical concerns over the reliability of reported BET areas. To solve this major issue, a new computational approach to accurately and systematically determine the BET area of nanoporous materials is developed. The software, called "BET surface identification" (BETSI), expands on the well-known Rouquerol criteria and makes an unambiguous BET area assignment possible