Periodic Mesoporous Organosilicas (PMOs) were developed in 1999 and are basically ordered templated mesoporous organosilicas, prepared by the combination of a surfactant as template and a ...silsesquioxane as the organosilica precursor. They were one of the first examples of the so-called "hybrid" organic/inorganic materials. In the years that followed, an amazing variety of functional groups, morphologies and applications has been developed. Some of these high-end applications, like low-k buffer layers in microelectronics, chiral catalysts, chromatographic supports, selective adsorbents and light-harvesting devices, have clearly shown their potential. In this review, we will give a comprehensive overview of all these different functionalities and applications that have been created for Periodic Mesoporous Organosilicas.
The degradation of methylene blue in aqueous solution as a model dye using a non thermal microwave (2.45 GHz) plasma jet at atmospheric pressure has been investigated. Argon has been used as feed gas ...and aqueous solutions with different concentrations of the dye were treated using the effluent from plasma jet in a remote exposure. The removal efficiency increased as the dye concentration decreased from 250 to 5 ppm. Methylene blue degrades after different treatment times, depending on the experimental plasma conditions. Thus, kinetic constants up to 0.177 min−1 were obtained. The higher the Ar flow, the faster the degradation rate. Optical emission spectroscopy (OES) was used to gather information about the species present in the gas phase, specifically excited argon atoms. Argon excited species and hydrogen peroxide play an important role in the degradation of the dye. In fact, the conversion of methylene blue was directly related to the density of argon excited species in the gas phase and the concentration of hydrogen peroxide in the aqueous liquid phase. Values of energy yield at 50% dye conversion of 0.296 g/kWh were achieved. Also, the use of two plasma applicators in parallel has been proven to improve energy efficiency.
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•Microwave plasma jets were applied for MB degradation in water.•Degradation of MB is related to H2O2 formation.•OES techniques were used to identify plasma active species triggering AOPs.•This plasma-over-liquid configuration provided good reaction rates and energy yields.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Cave animals converge evolutionarily on a suite of troglomorphic traits, the best known of which are eyelessness and depigmentation. We studied 11 cave and 10 surface populations of Astyanax ...mexicanus in order to better understand the evolutionary origins of the cave forms, the basic genetic structuring of both cave and surface populations, and the degree to which present day migration among them affects their genetic divergence.
To assess the genetic structure within populations and the relationships among them we genotyped individuals at 26 microsatellite loci. We found that surface populations are similar to one another, despite their relatively large geographic separation, whereas the cave populations are better differentiated. The cave populations we studied span the full range of the cave forms in three separate geographic regions and have at least five separate evolutionary origins. Cave populations had lower genetic diversity than surface populations, correlated with their smaller effective population sizes, probably the result of food and space limitations. Some of the cave populations receive migrants from the surface and exchange migrants with one another, especially when geographically close. This admixture results in significant heterozygote deficiencies at numerous loci due to Wahlund effects. Cave populations receiving migrants from the surface contain small numbers of individuals that are intermediate in both phenotype and genotype, affirming at least limited gene flow from the surface.
Cave populations of this species are derived from two different surface stocks denoted "old" and "new." The old stock colonized caves at least three times independently while the new stock colonized caves at least twice independently. Thus, the similar cave phenotypes found in these caves are the result of repeated convergences. These phenotypic convergences have occurred in spite of gene flow from surface populations suggesting either strong natural or sexual selection for alleles responsible for the cave phenotype in the cave environment.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this work we introduce a novel Periodic Mesoporous Organosilica (PMO) material, where the walls of the PMO are constructed of a long linear amine precursor ...(3-trimethoxysilylpropyl)diethylenetriamine at 5% or 10% and 1,2-bis(triethoxysilyl)ethane. This AM-PMO is very simple to synthesize and we show that it can be used for a wide range of applications. After synthesis of the PMO, the dangling amine groups can be grafted with an aldehyde/ketone to form Schiff base ligand functionalized PMOs. Such PMOs can subsequently be reacted with lanthanide salts or lanthanide complexes yielding luminescent hybrid PMO materials. A potential application of such materials is heavy metal sensing. The AM-PMO2_nano@o-van@Eu material (o-van = o-vanilin) shows significant “turn on” fluorescence in the presence of Hg2+ ions. The obtained AM-PMO material was also evaluated as a heterogeneous catalyst in Knoevenagel condensation reaction. The reactions between various aldehydes and malononitrile, could proceed smoothly in the presence of AM-PMO2 presenting high conversions of 85–99% with great selectivity (>99%). The AM-PMO additionally showed good CO2 adsorption behavior, similar to other previously reported PMOs with amine groups. However, the advantage of this material is its simplicity in preparation. In addition, the amine PMO can also be prepared in the form of nano-sized particles by altering the reaction parameters.
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•A new Periodic Mesoporous Organosilica (PMO) with a long dangling amine group was synthesized.•The amine groups of the PMO could further be functionalized with an aldehyde/ketone.•The PMO could be prepared at nano-size after altering the reaction conditions.•The PMO showed multifunctional applications: as a Hg2+ sensor, metal-free catalysts and CO2 adsorbent.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A novel technology was developed for the treatment of a stainless steel wastewater, which contains high nitrate concentration (6.8 g N-NO3 –/L), acidic pH (pH 3.3), and high concentration of metals. ...Denitrification was performed in an anaerobic swirling fluidized-bed membrane bioreactor (ASFMBR) with synthetic and real wastewater. The treatment concept was also integrated by a precipitation column in which high recirculation of the alkalinity produced from denitrification was introduced to drive the precipitation and recovery of metals present in the wastewater. The novel reactor configuration achieved high nitrate removal (>94%), and the acidic pH was efficiently neutralized in the reactor by recycling the alkalinity produced from denitrification. More than 40% of the metals present in the industrial wastewater was recovered. Membrane fouling was avoided by the hydrodynamic regime established in the ASFMBR. The treatment concept is promising to achieve an efficient removal of nitrate and recovery of metals from metallurgic wastewater.
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IJS, KILJ, NUK, PNG, UL, UM
Graphene-based materials are highly interesting in virtue of their excellent chemical, physical and mechanical properties that make them extremely useful as privileged materials in different ...industrial applications. Sonochemical methods allow the production of low-defect graphene materials, which are preferred for certain uses. Graphene nanosheets (GNS) have been prepared by exfoliation of a commercial micrographite (MG) using an ultrasound probe. Both materials were characterized by common techniques such as X-ray diffraction (XRD), Transmission Electronic Microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). All of them revealed the formation of exfoliated graphene nanosheets with similar surface characteristics to the pristine graphite but with a decreased crystallite size and number of layers. An exhaustive study of the particle size distribution was carried out by different analytical techniques such as dynamic light scattering (DLS), nanoparticle tracking analysis (NTA) and asymmetric flow field flow fractionation (AF4). The results provided by these techniques have been compared. NTA and AF4 gave higher resolution than DLS. AF4 has shown to be a precise analytical technique for the separation of GNS of different sizes.
GlobCurrent provides a variety of datasets aiming to describe global ocean circulation, especially when dealing with large-scale phenomena. It includes surface Stokes drift and geostrophic, Ekman, ...and total (geostrophic plus Ekman) currents. GlobCurrent uses the CNES-CLS13 mean dynamic topography estimation as well as data from sea surface drifters and wind reanalysis to improve the computation of ocean currents from altimetry data, which represents a significant advance in describing the total ocean current. The aim of this work is to compare the surface GlobCurrent estimates with a coupled ocean–wave numerical simulation (POLCOMS-WAM), drifting buoys, and altimeter observations when dealing with a Tehuano event,
i.e.,
intense (larger than 20 m s
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) and short duration (around 3–5 days) low-level winds blowing over the Gulf of Tehuantepec, Mexico. There is a good agreement between the wind-driven currents (Ekman currents plus Stokes drift) field from GlobCurrent and that estimated by POLCOMS–WAM, with the largest magnitudes
∼
0.8 m s
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in the region influenced by the highest winds’ speed. The geostrophic circulation patterns in the Gulf of Tehuantepec are similarly reproduced by GlobCurrent and POLCOMS-WAM. However, some differences were observed in the presence of an anticyclonic eddy located in the western part of the study area. Numerical results exhibit a more symmetrical eddy with geostrophic current speeds that, in agreement with along-track observations, exceed the 1 m s
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. Instead, the geostrophic eddy in GlobCurrent shows velocities of about 0.8 m s
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. As observed through drifting buoys in 2000, numerical results show that the anticyclonic eddy west of the GoT has strong ageostrophic currents related to a cyclogeostrophic balance, which is not included in GlobCurrent. This regional case study provides a guideline for future improvements of GlobCurrent products, in particular for the estimation of geostrophic and total currents.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Entropy-based tools are commonly used to describe the dynamics of complex systems. In the last few decades, non-extensive statistics, based on Tsallis entropy, and multifractal techniques have shown ...to be useful to characterize long-range interaction and scaling behavior. In this paper, an approach based on generalized Tsallis dimensions is used for the formulation of mutual-information-related dependence coefficients in the multifractal domain. Different versions according to the normalizing factor, as well as to the inclusion of the non-extensivity correction term are considered and discussed. An application to the assessment of dimensional interaction in the structural dynamics of a seismic real series is carried out to illustrate the usefulness and comparative performance of the measures introduced.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A suitable methodology of synthesis of coumarin derivatives by Pechmann reaction over heterogeneous solid acid catalysts in a free solvent media under microwave irradiation is described. Resorcinol, ...phenol and ethyl acetoacetate were selected as model reactants in the Pechmann condensation. The catalytic activity of several materials-Amberlyst-15, zeolite β and sulfonic acid functionalized hybrid silica-in solvent-free microwave-assisted synthesis of the corresponding coumarin derivatives has been investigated in detail. 7-Hydroxy-4-methylcoumarin and 4-methylcoumarin were obtained in 97% and 43% yields, respectively, over Amberlyst-15. This was the most active catalyst in the Pechmann reaction under studied conditions.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A molecular cobalt phthalocyanine (CoPc) catalyst has been integrated in an ethylene-bridged periodic mesoporous organosilica (PMO) to fabricate a hybrid material, CoPc-PMO, that catalyses CO2 ...reduction to CO in a photocatalytic system using Ru(bpy)32+ (bpy = 2,2′-bipyridine) as a photosensitizer and 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzodimidazole (BIH) as an electron donor. CoPc-PMO displays a Co-based turnover number (TONCO) of >6000 for CO evolution with >70% CO-selectivity after 4 h irradiation with UV-filtered simulated solar light, and a quantum yield of 1.95% at 467 nm towards CO. This system demonstrates a benchmark TONCO for immobilised CoPc-based catalysts towards visible light-driven CO2 reduction.
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