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Los recién nacidos que no alcanzan un peso acorde con su edad gestacional y sexo se pueden clasificar de distintos modos. En este artículo se definen los conceptos de pequeño para la edad gestacional (PEG) y crecimiento intrauterino reducido, así como las causas que las determinan con el objetivo de consensuar las definiciones en este tipo de pacientes que puedan ser susceptibles de tratamiento con hormona de crecimiento a lo largo de su infancia, así como de desarrollar enfermedad endocrinológica en la pubertad y en la edad adulta. La mayoría de los niños PEG experimentan un crecimiento recuperador espontáneo que suele completarse a los 2 años. En los PEG que no lo realizan, el tratamiento con hormona de crecimiento humana recombinante es efectivo, aumentando su talla adulta. Los PEG con crecimiento recuperador rápido y marcado en peso tienen mayor riesgo de desarrollar adrenarquia precoz, pubertad adelantada, síndrome del ovario poliquístico (niñas), resistencia a la insulina y obesidad; predisponiendo al desarrollo de diabetes tipo 2 y síndrome metabólico en la edad adulta. La condición de PEG puede afectar diferentes áreas del neurodesarrollo y manifestarse éstas en diferentes etapas de la vida; los PEG con crecimiento recuperador espontáneo tienen mejor pronóstico neurológico. Los posibles riesgos descritos asociados a la condición de PEG hacen imperativo la adecuada caracterización de estos pacientes al nacimiento, que permitirá su seguimiento prospectivo y la detección precoz de alteraciones.

RESUMENEste artículo explora aproximaciones críticas a la enseñanza del español asentadas en la pedagogía freireana, llevándolas, en particular, al contexto de la educación universitaria. Partimos de la experiencia pedagógica propia en universidades de Uruguay y EE.UU., intentando llevar el diálogo suscitado por la comparación de nuestros contextos particulares a un plano más allá de lo coyuntural, esperando así que nuestras reflexiones resulten fructíferas para un grupo amplio de educadoras y educadores. El enfoque de investigación y de escritura adoptado en este trabajo (de corte autoetnográfico) permite incluir nuestras subjetividades y nuestro compromiso con los programas en que fuimos docentes y también planificadoras. Tratamos algunas dificultades que surgen de la implementación de cursos que no siguen las dinámicas y tradiciones institucionales y también llamamos la atención sobre el potencial de propuestas que buscan visibilizar circunstancias de opresión, desigualdad e injusticia social para poder combatirlas.

Aza-boron-dipyrromethenes (Aza-BODIPYs) are an increasingly studied class of fluorophores. They can be seen as an azadipyrromethene (“aza-DIPY”) ligand rigidified by a metalloid, a boron atom. Based on this idea, a series of complexes of group 13 metals (aluminum and gallium) have been synthesized and characterized. The impact of the metal and of the nature of the substituents of aza-DIPY core were investigated. The photophysical and electrochemical properties were determined, and an X-ray structure of an azaGaDIPY was obtained. These data reveal that azaGaDIPY and azaAlDIPY exhibit significant red-shifted fluorescence compared to their analogue aza-BODIPY. Their emission can go up to 800 nm for the maximum emission length and up to NIR-II for the emission tail. This, associated with their electrochemical stability (no metal release whether oxidized or reduced) makes them a promising class of fluorophores for optical medical imaging. Moreover, X-ray structure and molecular modeling studies have shown that this redshift seems to be more due to the geometry around the boron/metal than to the nature of the metal.

Facile access to site-selective hetero-lanthanide molecules will open new avenues in the search of novel photophysical phenomena based on Ln-to-Ln′ energy transfer (ET). This challenge demands strategies to segregate efficiently different Ln metal ions among different positions in a molecule. We report here the one-step synthesis and structure of a pure [YbNdYb] (1) coordination complex featuring short Yb···Nd distances, ideal to investigate a potential distributive (i.e., from one donor to two acceptors) intramolecular ET from one Nd3+ion to two Yb3+centers within a well-characterized molecule. The difference in ionic radius is the mechanism allowing to allocate selectively both types of metal ion within the molecular structure, exploited with the simultaneous use of two β-diketone-type ligands. To assist the photophysical investigation of this heterometallic species, the analogues [YbLaYb] (2) and [LuNdLu] (3) have also been prepared. Sensitization of Yb3+and Nd3+in the last two complexes, respectively, was observed, with remarkably long decay times, facilitating the determination of the Nd-to-Yb ET within the [YbNdYb] composite. This ET was demonstrated by comparing the emission of iso-absorbant solutions of 1, 2, and 3and through lifetime determinations in solution and solid state. The comparatively high efficiency of this process corroborates the facilitating effect of having two acceptors for the nonradiative decay of Nd3+created within the [YbNdYb] molecule.

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The multistep synthesis of original antennas incorporating substituted [2.2]paracyclophane (pCp) moieties in the π-conjugated skeleton is described. These antennas, functionalized with an electron donor alkoxy fragment (A1) or with a fused coumarin derivative (A2), are incorporated in a triazacyclonane macrocyclic ligand L1or L2, respectively, for the design of Eu(III), Yb(III), and Gd(III) complexes. A combined photophysical/theoretical study reveals that A1presents a charge transfer character via through-space paracyclophane conjugation, whereas A2presents only local excited states centered on the coumarin–paracyclophane moiety, strongly favoring triplet state population via intersystem crossing. The resulting complexes EuL1and YbL2are fully emissive in red and near-infrared, respectively, whereas the GdL2complex acts as a photosensitizer for the generation of singlet oxygen.

Advances in personalized medicine are prompting the development of multimodal agents, that is, molecules that combine properties promoting various diagnostic and therapeutic applications. General approaches exploit chemical conjugation of therapeutic agents with contrast agents or the design of multimodal nanoplatforms. Herein, we report the design of a single molecule that exhibits potential for different diagnostic modes as well as the ability to sensitize oxygen, thus offering potential for photodynamic therapy. Exceptionally, this work involves the synthesis and chiral resolution of an enantiomeric pair of chiral monofluoroborates that contain a stereogenic boron atom. Combining experimental and theoretical chiroptical studies allowed the unambiguous determination of their absolute configuration. Photophysical investigations established the ability of this compound to sensitize oxygen even in the absence of heavy atoms within its structure. The synthesis of a chiral benzothiazole monofluoroborate paves a way to multimodal diagnostic tools (fluorescence and nuclear imaging) while also featuring potential therapeutic applications owing to its ability to activate oxygen to its singlet state for use in photodynamic therapy.

Singlet–triplet interconversions (intersystem crossing, ISC) in organic molecules are at the basis of many important processes in cutting-edge photonic applications (organic light-emitting devices, photodynamic therapy, etc.). Selection rules for these transitions are mainly governed by the spin–orbit coupling (SOC) phenomenon. Although the SOC relies on complex relativistic phenomena, theoreticians have, with time, developed increasingly sophisticated and efficient approaches to gain access to a satisfactory evaluation of its magnitude. However, recent works have highlighted the remarkable and somehow unexpected efficiency of dimers of small conjugated molecules in terms of ISC quantum yields, whose origin has not been completely investigated. In this work, we bring a coupled experimental and theoretical analysis of the origin of the unusually large ISC efficiency on a series of such dimers that differ by their nature (covalent or supramolecular). We show that considering the dynamical nature of the SOC, and especially its dependence on angular orientations between the dimer subunits sometimes overlooked in the literature, it is necessary to rationalize some counterintuitive experimental observations. This combined experimental and theoretical work paves the way for new molecular engineering rules for SOC control.

Enhanced near-infrared (NIR) luminescence from two structurally related heterobinuclear NaIYbIIIeight-cooridnate and heterobinuclear YbIIINaIeight-coordinate (CN = 8) complexes is reported and compared to a nine-coordinate (CN = 9) homoleptic complex. For the heteroleptic complex, [Yb(MPQ2)(acac)], the YbIIIcation is coordinated to two tridentate 2-(5-methylpyridin-2-yl)-8-quinolinate (MPQ) anions, with a bidentate acetylacetonate (acac) anion completing the coordination sphere. Instead, the heterobinuclear [NaYb(MPQ)4] complex comprises a total of four anionic MPQ ligands, two of which exhibit κ3-coordination to the YbIIIcation. The remaining two MPQ anions are unidentate toward the lanthanide and form μ2-bridges via the deprotonated quinolinate oxygens to a bound NaIcation which is also coordinated to the remaining nitrogen donor atoms. The structural properties of these complexes were evaluated by single-crystal X-ray diffraction (SXRD), continuous shape measure (CShM) analysis, and 1H NMR spectroscopy using a diamagnetic LuIIIanalogue. The corresponding photophysical properties were examined in CH2Cl2solution by using absorption and emission spectroscopy. For both the complexes, characteristic YbIIIemission is observed at ca. 980 nm, with recorded photoluminescence quantum yields (Φobs) and NIR luminescence lifetimes (τobs) of 2.0% and 14.0 μs vs 1.5% and 11.6 μs for the [NaYb(MPQ)4] and [Yb(MPQ)2(acac)] complexes, respectively. Interestingly, the eight-coordinate YbIIIcomplexes both have higher photoluminescence quantum yields when compared to the homoleptic [Yb(MPQ)3] complex, which has a reported quantum yield of 1.0% and a NIR lifetime determined herein of 13.3 μs under identical conditions. These results have been rationalized by considering the overall efficiency of the ligand-centered sensitization process (ηsens= Φisc× Φeet), together with subsequent radiative (kr) and nonradiative (knr) deactivation of the YbIIIcation. Moreover, the efficiency of the intersystem crossing (Φisc) and electronic energy transfer (Φeet) processes involved in the antennae effect have been quantified for the new complexes using a combination of nanosecond and femtosecond transient absorption techniques and have been compared to our previous results using [Ln(MPQ)3] complexes with Ln = Yb and Lu.

The reaction of the β-triketonate ligands tris(4-methylbenzoyl)methanide and tribenzoylmethanide with the trivalent lanthanoids Eu3+, Er3+, and Yb3+in the presence of Cs+afforded polymeric structures where the repeating units are represented by bimetallic tetranuclear assemblies of formulation {[Ln(Cs)(β-triketonate)4]2}n. The only exception is the structure formed by the reaction of tris(4-methylbenzoyl)methanide, Yb3+, and Cs+, which yielded a polymeric assembly where the repeating units are mononuclear Yb3+complexes bridged by Cs+cations. Photophysical measurements on the obtained materials confirmed efficient sensitization from the ligand excited states to the 4f* excited states of the three lanthanoids. According to transient absorption data, Er3+and Yb3+are sensitized via energy transfer from the triplet state of the β-triketonate ligands. On the other hand, energy transfer to Eu3+seems to occur via an alternative pathway, possibly directly via the singlet state or through ligand to metal charge transfer states. The emission measurements confirm efficient sensitization for all three lanthanoids and bright near-infrared emission for Er3+and Yb3+, a characteristic that seems to be linked to the specific chemical structure of the β-triketonate ligands.

Mammalian digit tip regeneration is linked to the presence of nail tissue, but a nail-explicit model is missing. Here, we report that nail-less double-ventral digits of ΔLARM1/2mutants that lack limb-specific Lmx1benhancers fail to regenerate. To separate the nail’s effect from the lack of dorsoventral (DV) polarity, we also interrogate double-dorsal double-nail digits and show that they regenerate. Thus, DV polarity is not a prerequisite for regeneration, and the nail requirement is supported. Transcriptomic comparison between wild-type and non-regenerative ΔLARM1/2mutant blastemas reveals differential upregulation of vascularization and connective tissue functional signatures in wild type versus upregulation of inflammation in the mutant. These results, together with the finding of Lmx1bexpression in the postnatal dorsal dermis underneath the nail and uniformly in the regenerative blastema, open the possibility of additional Lmx1b roles in digit tip regeneration, in addition to the indirect effect of mediating the formation of the nail.