El paraíso inhabitado de Ana María Matute: entre la realidad y la fantasía

Paraíso inhabitado, última obra de Ana María Matute, encierra muchos de los caracteres de su narrativa. Partiendo de ella, la identificación de motivos y topoi recurrentes evidenciarán la continuidad de un estilo singular. El mundo de los niños, la necesidad de huir de la vida cotidiana y buscar un refugio que permita dar alas a la imaginación, o la soledad y la incomunicación humanas son tratados con ternura inusitada y profundo lirismo

Effect of fatty acids on self-assembly of soybean lecithin systems

With the increasing interest in natural formulations for drug administration and functional foods, it is desirable a good knowledge of the phase behavior of lecithin/fatty acid formulations. Phase structure and properties of ternary lecithin/fatty acids/water systems are studied at 37. °C, making emphasis in regions with relatively low water and fatty acid content. The effect of fatty acid saturation degree on the phase microstructure is studied by comparing a fully saturated (palmitic acid, C16:0), monounsaturated (oleic acid, C18:1), and diunsaturated (linoleic acid, C18:2) fatty acids. Phase determinations are based on a combination of polarized light microscopy and small-angle X-ray scattering measurements. Interestingly, unsaturated (oleic acid and linoleic acid) fatty acid destabilizes the lamellar bilayer. Slight differences are observed between the phase diagrams produced by the unsaturated ones: small lamellar, medium cubic and large hexagonal regions. A narrow isotropic fluid region also appears on the lecithin-fatty acid axis, up to 8. wt% water. In contrast, a marked difference in phase microsctructure was observed between unsaturated and saturated systems in which the cubic and isotropic fluid phases are not formed. These differences are, probably, a consequence of the high Krafft point of the C16 saturated chains that imply rather rigid chains. However, unsaturated fatty acids result in more flexible tails. The frequent presence of, at least, one unsaturated chain in phospholipids makes it very likely a better mixing situation than in the case of more rigid chains. This swelling potential favors the formation of reverse hexagonal, cubic, and micellar phases. Both unsaturated fatty acid systems evolve by aging, with a reduction of the extension of reverse hexagonal phase and migration of the cubic phase to lower fatty acid and water contents. The kinetic stability of the systems seems to be controlled by the unsaturation of fatty acids.Dr. C.A. Godoy is grateful for her scholarship to the Agencia Española de Cooperación Internacional para el Desarrollo (AECID), Universidad de Alcalá and Banco Santander, through the “Becas Miguel de Cervantes Saavedra” Program, and to the Universidad del Valle for the bibliographic resources provided. Jaume Caelles from the SAXS-WAXS service at IQAC is gratefully for performing the measurements. Imma Carrera is acknowledged for sample preparation. Ignacio Jiménez is grateful for helping in graph improvement.Peer reviewe

Structure and phase equilibria of the soybean lecithin/PEG 40 monostearate/water system

PEG stearates are extensively used as emulsifiers in many lipid-based formulations. However, the scheme of the principles of the lipid-surfactant polymer interactions are still poorly understood and need more studies. A new phase diagram of a lecithin/PEG 40 monostearate/water system at 30 C is reported. First, we have characterized the binary PEG 40 monostearate/water system by the determination of the critical micelle concentration value and the viscous properties. Then, the ternary phase behavior and the influence of phase structure on their macroscopic properties are studied by a combination of different techniques, namely, optical microscopy, small-angle X-ray scattering, differential scanning calorimetry, and rheology. The phase behavior is complex, and some samples evolve even at long times. The single monophasic regions correspond to micellar, swollen lamellar, and lamellar gel phases. The existence of extended areas of phase coexistence (hexagonal, cubic, and lamellar liquid crystalline phases) may be a consequence of the low miscibility of S40P in the lecithin bilayer as well as of the segregation of the phospholipid polydisperse hydrophobic chains. The presence of the PEG 40 monostearate has less effect in the transformation to the cubic phase for lecithin than that found in other systems with simple glycerol-based lipids.The authors are grateful to Professor Michael Gradzielski for contacting Evonic Goldschmidt GmbH, who supplied us the TEGO® Acid S40P reagent. Marta Rodriguez is gratefully acknowledged for preparing the samples for SAXS analysis and Jaume Caelles from the SAXSWAXS service at IQAC for performing the measurements. Professor Pilar Tarazona is gratefully acknowledged for allowing the use of DSC equipment and Dr. Natali Fernandez for training in that technique. G. Zhang grateful for the Erasmus mobility grant, and M. Díaz grateful for her scholarship to the Agencia Española de Cooperación Internacional para el Desarrollo (AECID), Universidad de Alcalá and Banco Santander, through the “Becas Miguel de Cervantes Saavedra” Program. This paper is dedicated to the memory of our dear Prof. Ali Khan, who was a master in phase behavior.Peer reviewe

Arte urbano, ¿patrimonio cultural etnográfico de nosotros mismos?

[ES] En este texto se reflexiona sobre la dificultad que entraña comprender como patrimonio cultural el arte urbano, un fenómeno heterogéneo, cambiante y en proceso de construcción, demasiado cercano en el tiempo para contar con la suficiente perspectiva, pero que es un fiel reflejo de la sociedad de nuestra época. A pesar de que existen diversos ejemplos de reconocimiento patrimonial de obras concretas de características muy diferentes sigue siendo difícil enmarcar este tipo de producciones bajo alguno de los epígrafes existentes en la definición general de Patrimonio Cultural.Sánchez Pons, M. (2021). Arte urbano, ¿patrimonio cultural etnográfico de nosotros mismos?. Revista PH (Online). (103):187-189. https://doi.org/10.33349/2021.103.492618718910

Preparation and characterization of a supramolecular hydrogel made of phospholipids and oleic acid with a high water content

A hydrogel formed with phospholipids and fatty acids would be of great interest in the medical field due to the biological relevance that these molecules have in living organisms. However, the tendency of phospholipid mixtures to form vesicular or micellar aggregates at high water content hinders the formation of this type of hydrogel. In this study, a highly hydrated hydrogel (95% water) was formed with hydrogenated phosphatidylcholine and oleic acid. The preparation method involved a freeze-heating cycle of the aqueous lipid mixture, favouring the supramolecular aggregation of these molecules into a microscopic spongy morphology. Confocal fluorescence imaging showed that the microstructure of the hydrogel is made from the aggregation of giant multilamellar vesicles (5-20 μm diameter) while transmission electron microscopy revealed the existence of nanosized unilamellar vesicles (150 nm diameter) coexisting with lipid lamellae. Despite this type of aggregation, X-ray scattering experiments performed on the hydrogel show almost no correlation between lipid membranes. In terms of rheological properties, the material shows a prevalent elastic behaviour and low structural strength, a consequence of non-covalent interactions. With such properties and composition, this structured but easily deformable material might become a useful tool for biomedical applications

Influence of a series of pyridine ligands on the structure and photophysical properties of Cd(II) complexes

Among the group 12 metal ions, the Cd(II) ion presents an ionic radius comparable to that of Hg(II), while its electronegativity resembles that of Zn(II). Thus, these characteristics make it a suitable candidate for the synthesis of fluorescent coordination complexes given that it tends to maximize the chelation enhanced effect (CHEF), while its electronegativity helps to prevent the quenching of fluorescence generated by the heavy atom effect. Accordingly, herein, we performed a systematic study using Cd(II) compounds bearing α-acetamidocinnamic acid (HACA) and different N-, N^N- and N^N^N-pyridine ligands (dPy), namely pyridine (py) (1), 3-phenylpyridine (3-phpy) (2), 2,2′-bipyridine (2,2′-bipy) (3), 1,10-phenantroline (1,10-phen) (4) and 2,2′:6′,2′′-terpyridine (terpy) (5). The elucidation of their crystal structures revealed the formation of one coordination polymer (1), one dimer (3) and three monomers (2, 4, and 5). All the synthesized compounds were characterized via analytical and spectroscopic techniques, and their molecular and supramolecular structures were discussed. The photophysical properties of 1–5 in MeOH were studied and their quantum yields (Φ) were calculated, revealing an enhancement in the Φ value of the complexes generated by the CHEF of dPy

Synthesis and characterization of Pd(II), Pt(II), Cu(I), Ag(I) and Cu(II) complexes with N,O-hybrid pyrazole ligand

The coordination behavior of N,O-hybrid pyrazole-based metal-organic frameworks are described. 2- (3,5-Pyridyl-1H-pyrazol-1-yl)ethanol (L) and its Pd(II), Pt(II), Cu(I), Ag(I) and Cu(II) complexes with different anions have been synthesized and characterized by elemental analysis, conductivity, mass spectrometry, IR, 1H, 13C{1H} and 195Pt{1H} NMR spectroscopies. Complex 1 was also characterized by single crystal X-ray diffraction. For complex 7 has also been possible to perform the UV-Vis and magnetic susceptibility measurements. All complexes are monomers, except the complexes obtained by reaction of the ligand (L) with M(MeCO2)2 (M = Pd(II), Pt(II)) or CuBr2, which are dimers

Structural influence of the length and functionality of NN-donor spacers in Cd(II) ladder-type coordination polymers

The understanding of the effect generated by small differences of the organic ligands on the molecular and supramolecular arrangement of coordination polymers (CPs) is a key factor to control their properties. Therefore, the study of structurally related ligands differing in some factors inter alia functional group orientation, length, or functionality is a crucial task for crystal engineers. In this contribution, the reactions between Cd(OAc)2·2H2O, α-acetamidocinnamic acid (HACA) and different N,N-donor spacers with increasing length (pyrazine, pyz; 4,4’-bipyridine, 4,4’-bipy; 1,2-bis(4-pyridyl)ethylene, 1,2-bpe), as well as additional functionalities (4,4’-azopyridine, 4,4’-azpy) have been successfully performed. Their crystal structures have been elucidated revealing a family of ladder-type 1D CPs showing molecular arrays with single pillars for {[Cd2(μ-ACA)2(ACA)2(pyz)(H2O)2]·2EtOH}n (1), and double pillars for [Cd2(μ-ACA)2(ACA)2(4,4’-bipy)2]n (2), [Cd2(μ-ACA)2(ACA)2(1,2-bpe)2]n (3) and {[Cd2(μ-ACA)2(ACA)2(4,4’-azpy)2]·4,4’-azpy·9H2O}n (4). Remarkably, the effect of the addition of the azo group in 4 compared with 2 and 3 has led to a CP with the same molecular arrangement but different crystal packing, allowing the introduction of one non-coordinated 4,4’-azpy and nine water molecules. Finally, their solid-state UV-Vis and photoluminescence have been measured observing their blue-emitting properties

Amide-Driven Secondary Building Unit Structural Transformations between Zn(II) Coordination Polymers

The behavior of coordination polymers (CPs) against external stimuli has witnessed remarkable attention, especially when the resulting CPs present reversible molecular arrays. Accordingly, CPs with these characteristics can lead to differences in their properties owing to these structural differences, being promising for their use as potential molecular switches with diverse applications. Herein, we have synthesized four Zn(II) CPs bearing α-acetamidocinnamic acid (HACA) and 4,4′-bipyridine (4,4′-bipy). The reaction between Zn(OAc)2·2H2O, HACA, and 4,4′-bipy yields {[Zn(ACA)2(4,4′-bipy)]·EtOH}n (1), which was used for the formation of three CPs through dissolution–recrystallization structural transformations (DRSTs): {[Zn(ACA)2(4,4′-bipy)]·2MeOH}n (2), {[Zn2(μ-ACA)2(ACA)2(4,4′-bipy)]·2H2O}n (3), and {[Zn3(μ-ACA)6(4,4′-bipy)]·0.75CHCl3}n (4). The study of the four crystal structures revealed that their secondary building units (SBUs) comprise monomeric, dimeric, and trimeric arrangements linked by 4,4′-bipy ligands. The fundamental role of the utilized solvent and/or temperature, as well as their effect on the orientation of the amide moieties driving the formation of the different SBUs is discussed. Furthermore, the reversibility and interconversion between the four CPs have been assayed. Finally, their solid-state photoluminescence has evinced that the effect of the amide moieties not only predetermine a different SBU but also lead to a different emission in 4 compared with 1–3