Enviromental patterns and intermittent cascades

Real environmental flows are non-homogeneous, of fundamental interest is to determine and quantify turbulent diffusion from the available conditions of the flow, because the role of buoyancy and rotation modify the flow topology with often the dominant scale occurring when these two forces are in equilibrium. In geophysical flows both in the Atmosphere and the Ocean, the main forcing occurs at the Rossby deformation Radius with both direct and inverse energy cascades [1,2]. The role of the spectra of steady and decaying turbulence is important as well as its scale to scale conditions, so that a large range of scales has to be taken into account. When mixing and dispersion processes are studied, the behaviour of reactants or pollutants is seen to depend of both the intermittency of the vorticity and energy spectra. If irreversible molecular mixing has to be accounted, the range of scales spans from hundreds of Kilometres to the Bachelor or Kolmogorov sub millimeter scales. It is important to evaluate mixing and compare with oscillating grid experiments, Redondo [3], across a density interface measuring entrainment and grid decaying non steady mixing. These experiments are evaluated and compared with results of a Kinematic simulation model, Castilla [4]. The local vorticity is evaluated confirming the trapping of tracers in the strong vertical regions in 2D flows, but showing also that hyperdiffusion may also occur. Intermittency was evaluated using numerical evaluation of higher order moments in different types of 2D and 3D turbulence.Peer ReviewedPostprint (published version

Electrical Conductive Properties of 3D-PrintedConcrete Composite with Carbon Nanofibers

Electrical conductive properties in cement-based materials have received attention in recent years due to their key role in many innovative application (i.e., energy harvesting, deicing systems, electromagnetic shielding, and self-health monitoring). In this work, we explore the use 3D printing as an alternative method for the preparation of electrical conductive concretes. With this aim, the conductive performance of cement composites with carbon nanofibers (0, 1, 2.5, and 4 wt%) was explored by means of a combination of thermogravimetric analysis (TGA) and dielectric spectroscopy (DS) and compared with that of specimens prepared with the traditional mold method. The combination of TGA and DS gave us a unique insight into the electrical conductive properties, measuring the specimens’ performance while monitoring the amount in water confined in the porous network. Experimental evidence of an additional contribution to the electrical conductivity due to sample preparation is provided. In particular, in this work, a strong correlation between water molecules in interconnected pores and the σ(ω) values is shown, originating, mainly, from the use of the 3D printing technique.This work was born under the umbrella of the ECRETE project (RTI2018-098554-B-I00) funded by MCIN/AEI/10.13039/501100011033 (Program I+D+i RETOS INVESTIGACIÓN 2018), the project PoroPCM (PCI2019-103657) funded by MCIN/AEI/10.13039/501100011033 and co-founded by the European Union (Programación Conjunta Internacional 2019) and the project NRG-STORAGE (GA 870114) funded by the European Commission. Research conducted in the scope of the Transnational Common Laboratory (LTC) Aquitaine-Euskadi Network in Green Concrete

Cyclopentadienyl yttrium complexes with the [{Ti(η5-C5Me5)(μ-NH)}3(μ3-N)] metalloligand

The reactivity of the yttrium trichloride complex [Cl3Y{(μ3-NH)3Ti3(η5-C5Me5)3(μ3-N)}] (2) with a variety of main-group metal cyclopentadienyl reagents [M(C5H3R1R2)] (M = Li, Na, K, Tl) or [Mg(C5H5)2] has been investigated. Treatment of 2 with one equivalent of [Na(C5H5)] or [K(C5H4SiMe3)] gives the monocyclopentadienyl derivatives [(η5-C5H4R)Cl2Y{(μ3-NH)3Ti3(η5-C5Me5)3(μ3-N)}] (R = H (3), SiMe3 (4)). Analogous reaction of 2 with lithium [Li(C5H3R1R2)] or thallium [Tl(C5H5)] reagents (1 or 2 equivalents) leads to complexes [(η5-C5H3R1R2)2Y(μ-Cl)2M{(μ3-NH)3Ti3(η5-C5Me5)3(μ3-N)}] (M = Li, R1 = R2 = H (5), R1 = H, R2 = SiMe3 (6), R1 = R2 = SiMe3 (7); M = Tl, R1 = R2 = H (8)). Complex 2 reacts with [Mg(C5H5)2] to yield the ionic compound [(μ-Cl)3Mg2{(μ3-NH)3Ti3(η5-C5Me5)3(μ3-N)}2][{Y(η5-C5H5)2Cl}2(μ-Cl)] (9). In contrast to the metathesis of chloride ligands, the reaction of 2 with the lithium indenyl derivative [Li(C9H7)] at room temperature produces C9H8 and the precipitation of [Li(μ-Cl)3Y{(μ3-N)(μ3-NH)2Ti3(η5-C5Me5)3(μ3-N)}] (10). Crystallization of 10 in pyridine affords the lithium-free [Cl2(py)2Y{(μ3-N)(μ3-NH)2Ti3(η5-C5Me5)3(μ3-N)}] (11) complex. The X-ray crystal structures of 6 and 11 have been determined.Ministerio de Economía y Competitividad de España, Universidad de Alcal

Homo and Heteropolymetallic Group 4 Molecular Nitrides

Ministerio de Economía y Competitividad de España, Universidad de Alcal

Thermal Energy Storage (TES) Prototype Based on Geopolymer Concrete for High-Temperature Applications

Thermal energy storage (TES) systems are dependent on materials capable of operating at elevated temperatures for their performance and for prevailing as an integral part of industries. High-temperature TES assists in increasing the dispatchability of present power plants as well as increasing the efficiency in heat industry applications. Ordinary Portland cement (OPC)-based concretes are widely used as a sensible TES material in different applications. However, their performance is limited to operation temperatures below 400 °C due to the thermal degradation processes in its structure. In the present work, the performance and heat storage capacity of geopolymer-based concrete (GEO) have been studied experimentally and a comparison was carried out with OPC-based materials. Two thermal scenarios were examined, and results indicate that GEO withstand high running temperatures, higher than 500 °C, revealing higher thermal storage capacity than OPC-based materials. The high thermal energy storage, along with the high thermal diffusion coefficient at high temperatures, makes GEO a potential material that has good competitive properties compared with OPC-based TES. Experiments show the ability of geopolymer-based concrete for thermal energy storage applications, especially in industries that require feasible material for operation at high temperatures.This work was born under the umbrella of the project “Energy storage solutions based on concrete (E-CRETE)” (RTI2018-098554-B-I00) funded by MCIN/AEI/10.13039/501100011033 (Program I+D+i RETOS INVESTIGACIÓN 2018). Mohammad Rahjoo acknowledges the grant PRE2019-087676 funded by MCIN/AEI/10.13039/501100011033 and co-financed by the European Social Fund under the 2019 call for grants for predoctoral contracts for the training of doctors contemplated in the State Training Subprogram of the State Program for the Promotion of Talent and its Employability in R&D&I, within the framework of the State Plan for Scientific and Technical Research and Innovation 2017–2020. In addition, the economic support from POVAZSKA is acknowledged. Jorge S. Dolado acknowledges the funding from the Gobierno Vasco UPV/EHU (project no. IT1569-22)

Successive Protonation and Methylation of Bridging Imido and Nitrido Ligands at Titanium Complexes

The reactions of nitrido complexes [{Ti(eta5-C5Me5)(mu-NH)}3(mu3-N)] (1) and [{Ti(eta5-C5Me5)}4(mu3-N)4] (2) with electrophilic reagents ROTf (R = H, Me; OTf = OSO2CF3) in different molar ratios have allowed the structural characterization of a series of titanium intermediates en route to the formation of the ammonium salts [NR4]OTf and [NR4][Ti(eta5-C5Me5)(OTf)4]. The treatment of the trinuclear imido-nitrido complex 1 with 5.5 equiv of triflic acid in toluene at room temperature led to the dinuclear complex [Ti2(eta5-C5Me5)2(mu-N)(NH3)(mu-O2SOCF3)2(OTf)] (3) and [NH4]OTf. Compound 3, along with the ammonium salts [NMe4]OTf and [NMe4][Ti(eta5-C5Me5)(OTf)4] (5), was also obtained in the reaction of 1 with 8 equiv of methyl triflate in toluene at 100 °C. The trinuclear complex [Ti3(eta5-C5Me5)3(mu-N)(mu-NH)2(mu-O2SOCF3)(OTf)] (4), an intermediate in the formation of 3, was isolated in the treatment of 1 with 4 equiv of MeOTf, although compound 4 was prepared in better yield by treatment of 1 with Me3SiOTf (2 equiv). Addition of a large excess of MeOTf or HOTf reagents to solutions of 3 resulted in the clean formation of ammonium salts [NR4][Ti(eta5-C5Me5)(OTf)4] (R = Me (5), H (6)). Treatment of the tetranuclear nitrido complex [{Ti(eta5-C5Me5)}4(mu3-N)4] (2) with 1 equiv of ROTf in toluene afforded the precipitation of the ionic compounds [{Ti(eta5-C5Me5)}4(mu3-N)3(mu3-NR)][OTf] (R = H (8), Me (9)), while a large excess of HOTf led to the formation of [{Ti(eta5-C5Me5)}4(mu3-N)3(mu3-NH)][Ti(eta5-C5Me5)(OTf)4(NH3)] (10) by rupture of a fraction of tetranuclear molecules. Complex 2 reacted with 1 equiv of [M(eta5-C5H5)(CO)3H] (M = Mo, Cr) via hydrogenation of one nitrido ligand to give the molecular derivative [{Ti(eta5-C5Me5)}4(mu3-N)3(mu3-NH)] (11) and [{M(eta5-C5H5)(CO)3}2], while a second 1 equiv of [M(eta5-C5H5)(CO)3H] produced the ionic compounds....Ministerio de Ciencia, Innovación y Universidades de España, Ministerio de Educación y Ciencia de España, Universidad de Alcal

Reactivity with Electrophiles of Imido Groups Supported on Trinuclear Titanium Systems

Several trinuclear titanium complexes bearingamido mu-NHR, imido mu-NR, and nitrido mu(n)-N ligands have been prepared by reaction of [{Ti(eta(5)-C5Me5)(mu-NH)}(3)(mu(3)-N)] (1) with 1 equiv of electrophilic reagents ROTf (R = H, Me, SiMe3; OTf = OSO2CF3). Treatment of 1 with triflic acid or methyl triflate in toluene at room temperature affords the precipitation of compounds [Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)(mu-NH)(2)(mu-NH2)(OTf)] (2) or [Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)(mu-NH)(mu-NH2)(mu-NMe)(OTf)](3). Complexes 2 and 3 exhibit a fluxional behavior in solution consisting of proton exchange between mu-NH2 and mu-NH groups, assisted by the triflato ligand, as could be inferred from a dynamic NMR spectroscopy study. Monitoring by NMR spectroscopy the reaction course. of 1 with MeOTf allows the characterization of the methylamido intermediate [Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)(mu-NH)(2)(mu-NHMe)(OTf)] (4), which readily rearranges to give 3 by a proton migration from the NHMe amido group to the NH imido ligands. The treatment of 1 with 1 equiv ofMe3SiOTf produces the stable ionic complex [Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)(mu-NH)(2)(mu-NHSiMe3)][OTf] (5) with a disposition of the nitrogen ligands similar to that of 4. Complex 5 reacts with 1 equiv of [K{N(SiMe3)(2)}] at room temperature to give [Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)(mu-N)(mu-NH)(mu-NHSiMe3)] (6), which at 85 degrees C rearranges to the trimethylsilylimido derivative [Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)(mu-NH)(2)(mu-NHSiMe3)] (7). Treatment of 7 with [K{N(SiMe3)(2)}] affords the potassium derivative [K{(mu(3)-N)(mu(3)-NH)(mu(3)-NiSMe3)Ti-3(eta(C5Me5)-C-5)(3)(mu(3)-N)}] (8), which upon addition of 18-crown-6 leads to the ion pair [K(18-crown-6)] [Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)(mu-NH)(mu-NHSiMe3)] (9). The X-ray crystal structures of2, 5, 6, and 8 have been determined.Ministerio de Ciencia e Innovación de España, Comunidad de Madrid, Universidad de Alcalá, Ministerio de Educación y Ciencia de Españ

Electrophilic attack on trinuclear titanium imido-nitrido systems

Alkylation of [{Ti(eta(5)-C5Me5)(mu-NH)}(3)(mu(3)-N)] with MeOTf occurs at the imido ligands to produce the methylamido derivative [Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)(mu-NH)(2)(mu-NHMe)(OTf)] which readily rearranges to form the methylimido complex [Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)(mu-NH)(mu-NH2)(mu-NMe)(OTf)].Ministerio de Educación y Ciencia de España, Comunidad de Madrid, Universidad de Alcal

Urohidrosis as an overlooked cooling mechanism in long-legged birds

Behavioural thermoregulation could buffer the impacts of climate warming on vertebrates. Specifically, the wetting of body surfaces and the resulting evaporation of body fluids serves as a cooling mechanism in a number of vertebrates coping with heat. Storks (Ciconiidae) frequently excrete onto their legs to prevent overheating, a phenomenon known as urohidrosis. Despite the increasingly recognised role of bare and highly vascularised body parts in heat exchange, the ecological and evolutionary determinants of urohidrosis have been largely ignored. We combine urohidrosis data from a scientifically curated media repository with microclimate and ecological data to investigate the determinants of urohidrosis in all extant stork species. Our phylogenetic generalised linear mixed models show that high temperature, humidity and solar radiation, and low wind speed, promote the use of urohidrosis across species. Moreover, species that typically forage in open landscapes exhibit a more pronounced use of urohidrosis than those mainly foraging in waterbodies. Substantial interspecific variation in temperature thresholds for urohidrosis prevalence points to different species vulnerabilities to high temperatures. This integrated approach that uses online data sources and methods to model microclimates should provide insight into animal thermoregulation and improve our capacity to make accurate predictions of climate change’s impact on biodiversityinfo:eu-repo/semantics/publishedVersio

Molecular Nitrides with Titanium and Rare-Earth Metals

A series of titanium-group 3/lanthanide metal complexes have been prepared by reaction of [{Ti(eta(5)-C5Me5)(mu-NH)}(3)(mu(3)-N)] (1) with halide, triflate, or amido derivatives of the rare-earth metals. Treatment of 1 with metal halide complexes [MCl3(thf)(n)] or metal trifluoromethanesulfonate derivatives [M(O3SCF3)(3)] at room temperature affords the cube-type adducts [X3M{(mu(3)-NH)(3)Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)}] (X = Cl, M = Sc (2), Y (3), La (4), Sm (5), Er (6), Lu (7); X = OTf, M = Y (8), Sm (9), Er (10)). Treatment of yttrium (3) and lanthanum (4) halide complexes with 3 equiv of lithium 2,6-dimethylphenoxido [LiOAr] produces the aryloxido complexes [(ArO)(3)M{(mu(3)-NH)(3)Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)}] (M = Y (11), La (12)). Complex 1 reacts with 0.5 equiv of rare-earth bis(trimethylsilyl)amido derivatives [M{N(SiMe3)(2)}(3)] in toluene at 85-180 degrees C to afford the corner-shared double-cube nitrido compounds [M(mu(3)-N)(3)(mu(3)-NH)(3){Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)}(2)] (M = Sc (13), Y (14), La (15), Sm (16), Eu (17), Er (18), Lu (19)) via NH(SiMe3)(2) elimination. A single-cube intermediate [{(Me3Si)(2)N}Sc{(mu(3)-N)(2)(mu(3)-NH)Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)}] (20) was obtained by the treatment of 1 with 1 equiv of the scandium bis(trimethylsilyl)amido derivative [Sc{N(SiMe3)(2)}(3)]. The X-ray crystal structures of 2, 7, 11, 14, 15, and 19 have been determined. The thermal decomposition in the solid state of double-cube nitrido complexes 14, 15, and 18 has been investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) measurements, as well as by pyrolysis experiments at 1100 degrees C under different atmospheres (Ar, H-2/N-2, NH3) for the yttrium complex 14.Ministerio de Educación y Ciencia de España, Comunidad de Madrid, Universidad de Alcal