The presence of organic pollutants in the environment is a global threat to human health and ecosystems due to their bioaccumulation and long‐term persistence. Hereby a micromotor‐in‐sponge concept ...is presented that aims not only at pollutant removal, but towards an efficient in situ degradation by exploiting the synergy between the sponge hydrophobic nature and the rapid pollutant degradation promoted by the cobalt‐ferrite (CFO) micromotors embedded at the sponge's core. Such a platform allows the use of extremely low fuel concentration (0.13% H2O2), as well as its reusability and easy recovery. Moreover, the authors demonstrate an efficient multicycle pollutant degradation and treatment of large volumes (1 L in 15 min) by using multiple sponges. Such a fast degradation process is due to the CFO bubble‐propulsion motion mechanism, which induces both an enhanced fluid mixing within the sponge and an outward flow that allows a rapid fluid exchange. Also, the magnetic control of the system is demonstrated, guiding the sponge position during the degradation process. The micromotor‐in‐sponge configuration can be extrapolated to other catalytic micromotors, establishing an alternative platform for an easier implementation and recovery of micromotors in real environmental applications.
The micromotor‐in‐sponge platform provides an efficient in situ degradation due to the synergy of the sponge hydrophobic nature and the rapid pollutant degradation by motile cobalt‐ferrite (CFO) micromotors embedded at the sponge’ core. Its environmental degradation performance is demonstrated in large volumes by using extremely low fuel concentration, as well as its reusability and easy recovery.
The use of enzyme catalysis to power micro‐ and nanomotors exploiting biocompatible fuels has opened new ventures for biomedical applications such as the active transport and delivery of specific ...drugs to the site of interest. Here, urease‐powered nanomotors (nanobots) for doxorubicin (Dox) anticancer drug loading, release, and efficient delivery to cells are presented. These mesoporous silica‐based core–shell nanobots are able to self‐propel in ionic media, as confirmed by optical tracking and dynamic light scattering analysis. A four‐fold increase in drug release is achieved by nanobots after 6 h compared to their passive counterparts. Furthermore, the use of Dox‐loaded nanobots presents an enhanced anticancer efficiency toward HeLa cells, which arises from a synergistic effect of the enhanced drug release and the ammonia produced at high concentrations of urea substrate. A higher content of Dox inside HeLa cells is detected after 1, 4, 6, and 24 h incubation with active nanobots compared to passive Dox‐loaded nanoparticles. The improvement in drug delivery efficiency achieved by enzyme‐powered nanobots may hold potential toward their use in future biomedical applications such as the substrate‐triggered release of drugs in target locations.
The capability of enzyme‐propelled nanomotors to enhance drug delivery is investigated in this study. Urease‐powered nanomotors show active motion in ionic media and significantly improve the release of doxorubicin in the presence of urea. The synergy between the resulting catalytic products and the enhanced drug delivery results in higher cytotoxic effect toward HeLa cells.
Pollutant Removal
In article number 2107619, Maria Guix, Samuel Sánchez, and co‐workers present a micromotor‐in‐sponge platform that provides an efficient in situ degradation due to the synergy of ...the sponge hydrophobic nature and the rapid pollutant degradation by motile cobalt‐ferrite micromotors embedded at the sponge's core. Its environmental degradation performance is demon‐strated in large volumes by using extremely low fuel concentration, as well as its reusability and easy recovery.
In this paper we introduce a new class of quasilinear elliptic equations driven by the so-called double phase operator with variable exponents. We prove certain properties of the corresponding ...Musielak-Orlicz Sobolev spaces (an equivalent norm, uniform convexity, Radon-Riesz property with respect to the modular) and the properties of the new double phase operator (continuity, strict monotonicity, (S+)-property). In contrast to the known constant exponent case we are able to weaken the assumptions on the data. Finally we show the existence and uniqueness of corresponding elliptic equations with right-hand sides that have gradient dependence (so-called convection terms) under very general assumptions on the data. As a result of independent interest, we also show the density of smooth functions in the new Musielak-Orlicz Sobolev space even when the domain is unbounded.
In this paper, we study quasilinear elliptic equations driven by the double phase operator along with a reaction that has a singular and a parametric superlinear term and with a nonlinear Neumann ...boundary condition of critical growth. Based on a new equivalent norm for Musielak–Orlicz Sobolev spaces and the Nehari manifold along with the fibering method, we prove the existence of at least two weak solutions, provided the parameter is sufficiently small.
We present herein the development of a new polycationic molecular receptor, inspired by the ubiquitous cyclobis(paraquat-p-phenylene)cyclophane (“blue box”). Our analogue, the “white box”, has been ...easily self-assembled on a preparative scale in water, using a template-assisted process by acyl hydrazone bonding of complementary bis(pyridinium)xylylene tweezers, followed by kinetic trapping of the empty receptor. The obtained macrocycle was found to display a marked pH responsiveness in water, because of an abnormal acidity of the amide protons within its structure. Consequently, and because of the concurrence of rotational isomerism under acidic conditions (fixed at higher pH values), the compound was found to display a dual behavior as a conformationally locked/flexible molecular host, being able to recognize appropriate aromatic substrates, in a lock and key or induced fit fashion, by a conjunction of π–π, C–H···π, and, crucially, the hydrophobic effect.
In this paper we consider quasilinear elliptic equations driven by the variable exponent double phase operator with superlinear right-hand sides. Under very general assumptions on the nonlinearity, ...we prove a multiplicity result for such problems whereby we show the existence of a positive solution, a negative one and a solution with changing sign. The sign-changing solution is obtained via the Nehari manifold approach and, in addition, we can also give information on its nodal domains.
Gold‐catalyzed cycloisomerization reaction of 1‐bromoalkynes allowed for the preparation of a variety of 1‐bromocyclopentene derivatives. These have been used as substrates in a 3‐step synthetic ...sequence comprising a cross‐coupling reaction, followed by ozonolysis, and final condensation towards the corresponding 2,5‐disubstituted pyridine. In addition, bicyclic fused pyridines are achieved, including the first total synthesis of the natural product Sinensine B.
A 4‐step sequence for constructing pyridines from 1‐bromoalkynes, readily available substrates from feedstock materials, has been developed. The versatility of this approach arises, on the one hand, from the variety of cyclopentenes affordable through the key gold‐catalyzed cycloisomerization step and, on the other hand, from its modular nature that allows the introduction of an à la carte substituent at position 2 employing a Suzuki coupling.
The translation and adaptation of an assessment instrument into another language can be problematic, due, among other reasons, to sociocultural differences. This proved to be the case with the ...Spanish adaptation of the Students' Understanding of Models in Science (SUMS) questionnaire, a Likert‐type scale developed originally in English. In light of this, and with the additional aim of improving upon certain aspects of the original instrument, we report the development of a new questionnaire for assessing Spanish‐speaking students' understanding of the nature of models and their uses in science, providing validity evidence for the internal structure of the construct measured. The tool was developed by considering various dimensions of this concept that have been described in the literature, as well as the results of studies that piloted the SUMS questionnaire. For each dimension we drew up a set of items that could be rated using a Likert‐type scale; half of these items were positively worded with respect to an adequate understanding of models, and half were reverse worded. The adequacy of the proposed items was first assessed by a panel of experts, following which we examined the score structure obtained with the resulting instrument by administering it to a sample of 1272 students aged between 14 and 55 years. After purifying the instrument based on the results of these analyses, we obtained a final version of the questionnaire comprising 20 items distributed equally across four subscales: Beyond exact replicas, Purpose of models, Multiple models, and Changing models. The results obtained through factor analysis and structural equation modeling provide validity evidence for the internal structure of the construct measured. The questionnaire is quick to administer and is applicable to students across a wide range of ages and levels of education, including prospective science teachers.
Intensive sampling for vertebrate microfossils has yielded abundant fish remains in the Maastrichtian units of the Tremp Formation (southern Pyrenees, Catalonia, Spain). Samples were taken from eight ...new sites representing different palaeoenvironments including coastal wetlands and floodplains, in order to assess the fish diversity and to gain a better understanding of the last dinosaur-dominated ecosystems of northeastern Spain. The results suggest that a diverse ichthyofauna inhabited these transitional to inland fluvial settings throughout the Maastrichtian, comprising both marine and freshwater taxa. Three different chondrichthyans, eight basal neopterygians and at least seven teleostean species were found, the latter being more diverse than in other Maastrichtian localities in Europe. Fossil evidence from the studied late Maastrichtian assemblages suggests that teleosteans were present in all the trophic guilds. In addition, the oldest records for osteoglossids and perciforms in Europe, as well as for cypriniforms worldwide, are reported here. The findings from the southern Pyrenees also reveal ichthyofaunal turnover during the Late Cretaceous, with ‘holosteans’ being replaced by teleosteans. Moreover, Maastrichtian ichthyofaunas from the southern Pyrenees show Asian and North American biogeographical affinities.
•A diverse ichthyofauna inhabited the coastal and fluvial settings of the southern Pyrenees throughout the Maastrichtian.•The oldest records for Osteoglossidae and Perciformes in Europe are reported.•The oldest evidence of Cypriniformes worldwide is reported.•The southern Pyrenees record may represent a good example of the ichthyofaunal turnover during the Late Cretaceous.•The Maastrichtian icthyofauna from the southern Pyrenees reveals Asian and North American biogeographical affinities.
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