Wetting phenomenon in the liquid-vapor phase coexistence of a partially miscible Lennard-Jones binary mixture

We have carried out extensive equilibrium molecular dynamics (MD) simulations to study the structure and the interfacial properties in the liquid-vapor (LV) phase coexistence of partially miscible binary Lennard-Jones (LJ) mixtures. By analyzing the structural properties as a function of the miscibility parameter, $\alpha$, we found that at relatively low temperatures the system separates forming a liquid A-liquid B interface in coexistence with the vapor phase. At higher temperatures and, $0<\alpha\leq 0.5$, we found a temperature range, $T^{*}_{w}(\alpha) \leq T^{*} < T^{*}_{cons}(\alpha)$, where the liquid phases are wet by the vapor phase. Here, $T^{*}_{w}(\alpha)$ represents the wetting transition temperature (WTT) and $T^{*}_{cons}(\alpha)$ is the consolute temperature of the mixture. However, for $0.5< \alpha < 1$, no wetting phenomenon occurs. For the particular value, $\alpha=0.25$, we analyzed quantitatively the $T^{*}$ versus $\rho^{*}$, and $P^{*}$ versus $T^{*}$ phase diagrams and found, $T^{*}_{c}\simeq 1.25$, and $T^{*}_{cons}\simeq1.25$. We also studied quantitatively, as a function of temperature, the surface tension and the adsorption of molecules at the liquid-liquid interface. It was found that the adsorption shows a jump from a finite negative value up to minus infinity, when the vapor wets the liquid phases, suggesting that the wetting transition (WT) is of first order. The calculated phase diagram together with the wetting phenomenon strongly suggest the existence of a tricritical point. These results agree well with some experiments carried out in fluid binary mixtures.Comment: Enlarged version that include results of more extensive simulations. A total of 24 LaTeX pages that include 12 encapsulated poscript figures. To appear in PRE, Vol. 70, issue Sept. 1st (2004

Frontispiece: Lanthanide tetrazolate complexes combining single-molecule magnet and luminescence properties: The effect of the replacement of tetrazolate N3 by β-Diketonate Ligands on the anisotropy energy barrier

Three new sets of mononuclear LnIII complexes of general formulas [LnL3]·CH3OH (LnIII = Yb (1), Er (2), Dy (3), Gd (4) and Eu (5)), [LnL2(tmh)(CH3OH)]·n H2O·m CH3OH (LnIII = Yb (1b), Er (2b), Dy (3b), Gd (4b)) and [LnL2(tta)(CH3OH)]·CH3OH (LnIII = Yb (1c), Er (2c), Dy (3c), Gd (4c) have been prepared from the reaction of Ln(CF3SO3)·nH2O salts with the tridentate ligand 2-(tetrazolate-5-yl)-1,10- phenanthroline (HL). For the two latter sets, additionally with the respective β- diketonate ligands 2,2,6,6-tetramethylheptanoate (tmh) or 2-thenoyltrifluoroacetonate (tta). In the [LnL3]·CH3OH complexes the LnIII ions are coordinated to three phenanthroline-tetrazolate ligands showing a LnN9 coordination sphere. Dynamic ac magnetic measurements for 1 – 3 reveal that these complexes only exhibit single molecule magnet (SMM) behaviour when an external dc magnetic field is applied, with Ueff values of 11.7 K (1), 16.0 K (2) and 20.2 K (3). When the tridentate phenanthrolinetetrazolate ligand is replaced by one molecule of methanol and the β-diketonate ligand tmh (1b – 3b) or tta (1c – 3c), a significant increase in Ueff occurs and, in the case of the DyIII derivates 3b and 3c, out-of-phase χ’’ signals below 15 K and 10 K, respectively, are observed under zero-dc magnetic field. CASSCF+RASSI ab initio calculations performed on the DyIII derivates support the experimental results. Thus, for 3 the ground Kramers’ doublet is far from being axial and the first excited state is found to be very close in energy to the ground state so the relaxation barrier in this case is almost negligible. Conversely, for 3b and 3c, the ground Kramers’ doublet is axial with a small quantum tunneling of the magnetization (QTM) and the energy difference between the ground and first Kramers’ doublets is much higher, which allows these compounds to behave as SMMs at zero-field. Moreover, these calculations support the larger Ueff observed for 3b compared to 3c. Additionally, the solid-state photophysical properties of 1, 2, 4 and 5 show that the phenanthroline tetrazolate ligand can act as an effective antenna to sensitize the characteristic YbIII, ErIII and EuIII emissions through an energy transfer process

Lanthanide tetrazolate complexes combining single-molecule magnet and luminescence properties: the effect of the replacement of tetrazolate n3 by β-diketonate ligands on the anisotropy energy barrier

Three new sets of mononuclear LnIII complexes of general formulas [LnL3]⋅CH3OH [LnIII=Yb (1), Er (2), Dy (3), Gd (4), and Eu (5)], [LnL2(tmh)(CH3OH)]⋅n H2O⋅m CH3OH [LnIII=Yb (1 b), Er (2 b), Dy (3 b), Gd (4 b)], and [LnL2(tta)(CH3OH)]⋅CH3OH [LnIII=Yb (1 c), Er (2 c), Dy (3 c), Gd (4 c)] were prepared by the reaction of Ln(CF3SO3)⋅n H2O salts with the tridentate ligand 2-(tetrazol-5-yl)-1,10-phenanthroline (HL) and, for the last two sets, additionally with the β-diketonate ligands 2,2,6,6-tetramethylheptanoate (tmh) and 2-thenoyltrifluoroacetonate (tta), respectively. In the [LnL3]⋅CH3OH complexes the LnIII ions are coordinated to three phenanthroline tetrazolate ligands with an LnN9 coordination sphere. Dynamic ac magnetic measurements on 1–3 reveal that these complexes only exhibit single-molecule magnet (SMM) behavior when an external dc magnetic field is applied, with Ueff values of 11.7 K (1), 16.0 K (2), and 20.2 K (3). When the tridentate phenanthroline tetrazolate ligand is replaced by one molecule of methanol and the β-diketonate ligand tmh (1 b–3 b) or tta (1 c–3 c), a significant increase in Ueff occurs and, in the case of the DyIII complexes 3 b and 3 c, out-of-phase χ′′ signals below 15 and 10 K, respectively, are observed in zero dc magnetic field. CASSCF+RASSI ab initio calculations performed on the DyIII complexes support the experimental results. Thus, for 3 the ground Kramers’ doublet is far from being axial and the first excited state is found to be very close in energy to the ground state, so the relaxation barrier in this case is almost negligible. Conversely, for 3 b and 3 c, the ground Kramers’ doublet is axial with a small quantum tunneling of the magnetization, and the energy difference between the ground and first Kramers’ doublets is much higher, which allows these compounds to behave as SMMs at zero field. Moreover, these calculations support the larger Ueff observed for 3 b compared to 3 c. Additionally, the solid-state photophysical properties of 1, 2, 4, and 5 show that the phenanthroline tetrazolate ligand can act as an effective antenna to sensitize the characteristic YbIII, ErIII, and EuIII emissions through an energy-transfer process

Metastable liquid lamellar structures in binary and ternary mixtures of Lennard-Jones fluids

We have carried out extensive equilibrium molecular dynamics (MD) simulations to investigate the Liquid-Vapor coexistence in partially miscible binary and ternary mixtures of Lennard-Jones (LJ) fluids. We have studied in detail the time evolution of the density profiles and the interfacial properties in a temperature region of the phase diagram where the condensed phase is demixed. The composition of the mixtures are fixed, 50% for the binary mixture and 33.33% for the ternary mixture. The results of the simulations clearly indicate that in the range of temperatures $78 < T < 102 ^{\rm o}$K, --in the scale of argon-- the system evolves towards a metastable alternated liquid-liquid lamellar state in coexistence with its vapor phase. These states can be achieved if the initial configuration is fully disordered, that is, when the particles of the fluids are randomly placed on the sites of an FCC crystal or the system is completely mixed. As temperature decreases these states become very well defined and more stables in time. We find that below $90 ^{\rm o}$K, the alternated liquid-liquid lamellar state remains alive for 80 ns, in the scale of argon, the longest simulation we have carried out. Nonetheless, we believe that in this temperature region these states will be alive for even much longer times.Comment: 18 Latex-RevTex pages including 12 encapsulated postscript figures. Figures with better resolution available upon request. Accepted for publication in Phys. Rev. E Dec. 1st issu

Monitoring spin-crossover phenomena via Re(I) luminescence in hybrid Fe(II) silica coated nanoparticles

Financial support from Projects CTQ2014-56312-P and PGC2018-102052-B-C21 financed by MCIN/AEI/10.13039/501100011033/FEDER "Una manera de hacer Europa", the Junta de Andalucia (FQM-195), Feder project A-FQM-172UGR18 and the University of Granada is gratefully acknowledged. I.-F. Diaz-Ortega and J.-R Jimenez are also thankful to the Junta de Andalucia for Postdoctoral research fellowships.Bare (1) and silica coated (1@SiO2) spin crossover (SCO) nanoparticles based on the polymer {[Fe (NH2Trz)3](BF4)2}n have been prepared following a water-in-oil synthetic procedure. For 1, the critical temperatures of the spin transition are TC↓ = 214.6 K and TC↑ = 220.9 K. For 1@SiO2, the abruptness of the transition is enhanced and the critical temperatures are centred at room temperature (TC↓ = 292.1 K and TC↑ = 296.3 K). An inert Re(I) complex of formula [Re(phen)(CO)3(PETES)](PF6) (phen = 1, 10-phenanthroline; PETES = 2(4-pyridylethyl)triethoxysilane) (Re) was also synthesized yielding intense green emission centred at λem = 560 nm. The grafting of this complex on the silica shell of 1@SiO2 led to a bifunctional SCO-luminescence composite (1@SiO2/Re) whose luminescence properties were tuned by the spin state switching. Temperature-variable photophysical studies showed that luminescence and spin transition were synchronized through a radiative (trivial) energy transfer mechanism between the Re(I) and the Fe(II)-LS (LS, Low Spin) centres.FEDER "Una manera de hacer Europa" CTQ2014-56312-P PGC2018-102052-B-C21Junta de Andalucia FQM-195European Commission A-FQM-172UGR18University of GranadaJunta de Andaluci

The Structure of the Vortex Liquid at the Surface of a Layered Superconductor

A density-functional approach is used to calculate the inhomogeneous vortex density distribution in the flux liquid phase at the planar surface of a layered superconductor, where the external magnetic field is perpendicular to the superconducting layers and parallel to the surface. The interactions with image vortices are treated within a mean field approximation as a functional of the vortex density. Near the freezing transition strong vortex density fluctuations are found to persist far into the bulk liquid. We also calculate the height of the Bean-Livingston surface barrier.Comment: 8 pages, RevTeX, 2 figure

The value of selected in vitro and in silico methods to predict acute oral toxicity in a regulatory context: results from the European Project ACuteTox

ACuteTox is a project within the 6th European Framework Programme which had as one of its goals to develop, optimise and prevalidate a non-animal testing strategy for predicting human acute oral toxicity. In its last 6months, a challenging exercise was conducted to assess the predictive capacity of the developed testing strategies and final identification of the most promising ones. Thirty-two chemicals were tested blind in the battery of in vitro and in silico methods selected during the first phase of the project. This paper describes the classification approaches studied: single step procedures and two step tiered testing strategies. In summary, four in vitro testing strategies were proposed as best performing in terms of predictive capacity with respect to the European acute oral toxicity classification. In addition, a heuristic testing strategy is suggested that combines the prediction results gained from the neutral red uptake assay performed in 3T3 cells, with information on neurotoxicity alerts identified by the primary rat brain aggregates test method. Octanol-water partition coefficients and in silico prediction of intestinal absorption and blood-brain barrier passage are also considered. This approach allows to reduce the number of chemicals wrongly predicted as not classified (LD(50)>2000mg/kg b.w.).Peer Reviewe

Contribución de la interferometría SAR diferencial (InSAR) al estudio de la subsidencia del terreno de la Vega Media del Segura (Murcia): experiencias y tendencias futuras

XVII Congreso de la Asociación Española de Teledetección. Murcia 3-7 octubre 2017La Vega Media del Segura (VMS) se localiza en el sector este de la Cordillera Bética. El valle está relleno por sedimentos recientes (Holoceno-Plioceno) potencialmente deformables que han sido depositados por la acción de los ríos Segura y Guadalentín. La extracción de agua subterránea de los niveles permeables que constituyen el acuífero conlleva la consolidación de los materiales deformables, dando lugar a asientos de la superficie del terreno. La Interferometría SAR diferencial (InSAR) es una técnica remota que permite monitorizar de forma efectiva y precisa amplias extensiones del territorio. En este trabajo se describe las diferentes experiencias llevadas a cabo por los autores en la VMS, que han permitido avanzar en el entendimiento del funcionamiento hidrogeológico del acuífero para la comprensión del comportamiento geomecánico del subsuelo, así como para monitorizar los desplazamientos del terreno desde el año 1994 usando imágenes ERS, ENVISAT y TerraSAR-X, contribuyendo de forma efectiva al estudio, caracterización y modelización del fenómeno. Por último, se describen las tareas futuras a desarrollar haciendo uso de nuevos sensores SAR con el fin de asegurar la continuidad de la información disponible para el estudio de este fenómeno a lo largo del tiempo.Departamento de Ingeniería Civil, Universidad de Alicante, EspañaGeohazards InSAR Laboratory and Modeling Group, Instituto Geológico y Minero de España, EspañaDepartamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, EspañaDepartamento de Teoria Senyal i Comunicacions, Universitat Politècnica de Catalunya, EspañaDepartment of Earth Sciences, Environment and Resources, University of Naples, EspañaDares Technology, Barcelona, Españ

Una herencia en Manaos (anotaciones sobre historia ambiental, ecología política y agroecología en una perspectiva latinoamericana)

Este artículo pretende explorar algunas vinculaciones de la agroecología con la historia ambiental, en sus escalas macro y micro, y con la ecología política. Una clave de interpretación es un interrogante sobre la identidad latinoamericana, que es percibida como articulación y sedimentación de varias herencias diferentes,en la cultura, la tecnología, los paisajes y la naturaleza

Database of spatial distribution of non indigenous species in Spanish marine waters

Research in marine Spanish waters are focused on several actions to achieve an effectively management on protected areas, with the active participation of the stakeholders and research as basic tools for decision-making. Among these actions, there is one about the knowledge and control on NIS. One of its objectives is the creation of NIS factsheets, which are going to be added to the National Marine Biodiversity Geographical System (GIS) providing complementary information about taxonomic classification, common names, taxonomic synonyms, species illustrations, identification morphological characters, habitat in the native and introduced regions, biological and ecological traits, GenBank DNA sequences, world distribution, first record and evolution in the introduced areas, likely pathways of introduction, effects in the habitats and interaction with native species, and potential management measures to apply. The database will also provide data for (1) the European online platforms, (2) the environmental assessment for the Descriptor 2 (D2-NIS) of the EU Marine Strategy Framework Directive (MSFD), as well as (3) supporting decisions made by stakeholders. It is the result of extensive collaboration among scientist, manager’s and citizen science in the Spanish North-Atlantic, South-Atlantic, Gibraltar Strait-Alboran, Levantine-Balearic and Canary Islands marine divisions, providing an updated overview of the spatial distribution of relevant extended and invasive NIS of recent and established NIS introduced by maritime transport and aquaculture pathways, as well as on cryptogenic or native species in expansion due to the climatic water warming trend