[The impact of COVID-19 on the health status of older people in Chile]. / COVID-19 y personas mayores en Chile: lecciones de dos años de pandemia.

The article presents the main impact of COVID-19 pandemic on the health status of older people, systematizing the information about the direct impact of the pandemic in terms of number of cases, hospitalizations, deaths, the policies implemented for the prevention and management of COVID-19 in older people and the indirect impact of the two years of pandemic. Adopting a broad definition of health, the need to monitor and recover health care of older people is highlighted. The recovery of their functionality and mental health must be emphasized. The policies towards institutionalized older people must be revised. These areas should be the focus of health care policies for older people in Chile.

Crystal Structure and Hirshfeld Surface Analysis of Acetoacetanilide Based Reaction Products.

We report an unprecedented multicomponent reaction of acetoacetanilide with malononitrile leading to a structurally novel bicyclic product (9) in a high yield. The structure has been confirmed by X-ray crystallography and comparative Hirshfeld surface analysis of 5-cyano-2-hydroxy-2-methyl-N-phenyl-4-(yridine-4-yl)-6-(thiophen-2-yl)-3,4-dihydro-2H-pyran-3-carboxamide 2, 5-cyano-2-hydroxy-2-methyl-6-oxo-N-phenyl-4-(thiophen-2-yl)piperidine-3-carboxamide 4 and 2-(8-amino-7,8a-dicyano-1-imino-4a-methyl-3-oxo-2-phenyl-1,3,4,4a,5,8a-hexahydroisoquinolin-6(2H)-ylidene)-N-phenylacetamide 9.

Application of process system engineering tools to the fed-batch production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from a vinasses-molasses Mixture.

Fed-batch production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer using vinasses-molasses mixture is carried out in this work by implementing different process systems engineering tools. Two fed-batch strategies are tested experimentally at 5 L scale, considering only offline information: (1) offline optimizing control and (2) exponential feeding. Application of these strategies showed that different feeding profiles result in different dynamic behaviour, influencing both, yield and biopolymer properties. As offline-based feeding strategies do not consider information of the culture status, they cannot deal with uncertainties. Therefore, a closed loop control strategy was implemented, which uses biomass and substrate information predicted online by soft-sensors. Results demonstrated the technical feasibility to produce biopolymer using a 75/25%vol. vinasses-molasses mixture. Successful implementation of the soft-sensor-based control strategy was evidenced at pilot plant scale, where sugar concentration was kept almost constant for 14 h, while obtaining the desired copolymer. Thus, proposed control strategy could be of interest at industrial-scale.

The Positional Isomeric Effect on the Structural Diversity of Cd(II) Coordination Polymers, Using Flexible Positional Isomeric Ligands Containing Pyridyl, Triazole, and Carboxylate Fragments.

To systematically investigate the influence of the positional isomeric effect on the structures of polymer complexes, we prepared two new polymers containing the two positional isomers ethyl 5-methyl-1-(pyridin-3-yl)-1H-1,2,3-triazole-3-carboxylate (L1) and ethyl-5-methyl-1-(pyridin-3-yl)-1H-1,2,3-triazole-4-carboxylate (L2), as well as Cd(II) ions. The structures of the metal⁻organic frameworks were determined by a single crystal XRD analysis. The compound [Cd(L1)2·4H2O] (1), is a hydrogen bond-induced coordination polymer, whereas the compound [Cd(L2)4·5H2O]n (2) is a three-dimensional (3-D) coordination polymer. Their structures and properties are tuned by the variable N-donor positions of the ligand isomers. This work indicates that the isomeric effect of the ligand isomers plays an important role in the construction of the Cd(II) complexes. In addition, the thermal and luminescent properties are reported in detail.

A classical simulation of nonlinear Jaynes-Cummings and Rabi models in photonic lattices: reply to comment.

We regret that such a misleading comment [Opt. Express (2013)] has been made to our paper. First Lo states in his abstract that "However, the nonlinear Rabi model has already been rigorously proven to be undefined" to later recoil and use the contradictory statement "(. . . ) regarding the BS model with the counter-rotating terms (. . . ) Lo and his co-authors have proven that the model is well defined only if the coupling stregth g is smaller than a critical value gc = ω/4". While Lo focuses on the validity of the quantum optics Hamiltonians and gives a misleading assesment of our manuscript, the focus of our paper is the method to map such a set of Hamiltonians from quantum optics to photonic lattices. Our method is valid for the given class of Hamiltonians and, indeed, precaution must be exerted on the paramater ranges where those Hamiltonians are valid and where their classical simulation is feasible. These parameter ranges have to be specified in for each particular case studied. Furthermore, we gave as example the Buck-Sukumar model including counter-rotating terms which is a valid Hamiltonian for some coupling parameters.

Advances in chitosan and chitosan derivatives for biomedical applications in tissue engineering: An updated review.

In recent years, chitosan (CS) has received much attention as a functional biopolymer for various applications, especially in the biomedical field. It is a natural polysaccharide created by the chemical deacetylation of chitin (CT) that is nontoxic, biocompatible, and biodegradable. This natural polymer is difficult to process; however, chemical modification of the CS backbone allows improved use of functional derivatives. CS and its derivatives are used to prepare hydrogels, membranes, scaffolds, fibers, foams, and sponges, primarily for regenerative medicine. Tissue engineering (TE), currently one of the fastest-growing fields in the life sciences, primarily aims to restore or replace lost or damaged organs and tissues using supports that, combined with cells and biomolecules, generate new tissue. In this sense, the growing interest in the application of biomaterials based on CS and some of its derivatives is justifiable. This review aims to summarize the most important recent advances in developing biomaterials based on CS and its derivatives and to study their synthesis, characterization, and applications in the biomedical field, especially in the TE area.

A classical simulation of nonlinear Jaynes-Cummings and Rabi models in photonic lattices.

The interaction of a two-level atom with a single-mode quantized field is one of the simplest models in quantum optics. Under the rotating wave approximation, it is known as the Jaynes-Cummings model and without it as the Rabi model. Real-world realizations of the Jaynes-Cummings model include cavity, ion trap and circuit quantum electrodynamics. The Rabi model can be realized in circuit quantum electrodynamics. As soon as nonlinear couplings are introduced, feasible experimental realizations in quantum systems are drastically reduced. We propose a set of two photonic lattices that classically simulates the interaction of a single two-level system with a quantized field under field nonlinearities and nonlinear couplings as long as the quantum optics model conserves parity. We describe how to reconstruct the mean value of quantum optics measurements, such as photon number and atomic energy excitation, from the intensity and from the field, such as von Neumann entropy and fidelity, at the output of the photonic lattices. We discuss how typical initial states involving coherent or displaced Fock fields can be engineered from recently discussed Glauber-Fock lattices. As an example, the Buck-Sukumar model, where the coupling depends on the intensity of the field, is classically simulated for separable and entangled initial states.

The Methylene Spacer Matters: The Structural and Luminescent Effects of Positional Isomerism of n-Methylpyridyltriazole Carboxylate Semi-Rigid Ligands in the Structure of Zn(II) Based Coordination Polymers.

Two Zn(II) coordination polymers (CPs) based on n-methylpyridyltriazole carboxylate semi-rigid organic ligands (n-MPTC), with n = 3 (L1) and 4 (L2), have been prepared at the water n-butanol interphase by reacting Zn(NO3)2·4H2O with NaL1 and NaL2. This allows us to systematically investigate the influence of the isomeric positional effect on their structures. The organic ligands were obtained by saponification from their respective ester precursors ethyl-5-methyl-1-(pyridin-3-ylmethyl)-1H-1,2,3-triazole-4-carboxylate (P1) and ethyl-5-methyl-1-(pyridin-4-ylmethyl)-1H-1,2,3-triazole-4-carboxylate (P2), resulting in their corresponding sodium salt forms, 3-MPTC, and 4-MPTC. The structure of the Zn(II) CPs determined by single-crystal X-ray diffraction reveals that both CPs have 2D supramolecular hydrogen bond networks. The 2D supramolecular network of [Zn(L1)]n (1) is built up by hydrogen bond interactions between oxygen and hydrogen atoms between neighboring n-methylpyridyltriazole molecules, whereas in [Zn(L2)·4H2O]n (2) the water molecules link 1D polymeric chains forming a 2D supramolecular aggregate. The structures of 1 and 2 clearly show that the isomeric effect in the semi-rigid ligands plays a vital role in constructing the Zn(II) coordination polymers, helped by the presence of the methylene spacer group, in the final structural conformation. The structures of 1 and 2 significantly affect their luminescent properties. Thus, while 2 shows strong emission at room temperature centered at 367 nm, the emission of 1 is quenched substantially.

Combined use of novel chitosan-grafted N-hydroxyethyl acrylamide polyurethane and human dermal fibroblasts as a construct for in vitro-engineered skin.

A rich plethora of information about grafted chitosan (CS) for medical use has been reported. The capability of CS-grafted poly(N-hydroxyethyl acrylamide) (CS-g-PHEAA) to support human dermal fibroblasts (HDFs) in vitro has been proven. However, CS-grafted copolymers lack good stiffness and the characteristic microstructure of a cellular matrix. In addition, whether CS-g-PHEAA can be used to prepare a scaffold with a suitable morphology and mechanical properties for skin tissue engineering (STE) is unclear. This study aimed to show for the first time that step-growth polymerizations can be used to obtain polyurethane (PU) platforms of CS-g-PHEAA, which can also have enhanced microhardness and be suitable for in vitro cell culture. The PU prepolymers were prepared from grafted CS, polyethylene glycol, and 1,6-hexamethylene diisocyanate. The results proved that a poly(saccharide-urethane) [(CS-g-PHEAA)-PU] could be successfully synthesized with a more suitable microarchitecture, thermal properties, and topology than CS-PU for the dynamic culturing of fibroblasts. Cytotoxicity, proliferation, histological and immunophenotype assessments revealed significantly higher biocompatibility and cell proliferation of the derivative concerning the controls. Cells cultured on (CS-g-PHEAA)-PU displayed a quiescent state compared to those cultured on CS-PU, which showed an activated phenotype. These findings may be critical factors in future studies establishing wound dressing models.

Butane-1,4-diyl bis-(pyridine-3-carboxyl-ate).

Mol-ecules of the title compound (alternative name: butane-1,4-diyl dinicotinate), C(16)H(16)N(2)O(4), lie on a inversion centre, located at the mid-point of the central C-C bond of the aliphatic chain, giving one half-mol-ecule per asymmetric unit. The butane chain adopts an all-trans conformation. The dihedral angle between the mean plane of the butane-3-carboxyl-ate group [for the non-H atoms, maximum deviation = 0.0871 (15) Å] and the pyridine ring is 10.83 (7)°. In the crystal, mol-ecules lie in planes parallel to (122). The structure features weak π-π inter-actions with a centroid-centroid distance of 3.9281 (11) Å.

Disorder in the anionic part of catena-poly[[(pyrazine-2-carboxyl-ato)copper(II)]-µ-pyrazine-2-carboxyl-ato].

The title compound, [Cu(C(5)H(3)N(2)O(2))(0.88)(C(6)H(4)NO(2))(1.12)](n), is characterized by disorder of the anion, resulting from a statistical occupation in a 0.44 (3):0.56 (3) ratio of pyrazine-2-carboxylate and pyridine-2-carboxylate. The compound was isolated during attempts to synthesize a mixed-ligand coordination polymer by solvothermal reaction between copper(II) nitrate and equimolar mixtures of pyrazine-2-carboxylic acid and pyridine-2-carb-oxy-lic acid in a mixture of water and EtOH. The difference in the two components of the compound is due to substitutional disorder of a CH group for one of the N atoms of the pyrazine ring which share the same site in the structure. In the crystal structure, the Cu(II) atom lies on an inversion centre and is six-coordinated in a distorted N(2)O(4) geometry. The carboxyl-ate group carbonyl O atoms are weakly coordinated to an equivalent Cu(II) atom that is translated one unit cell in the a-axis direction, thus forming a polymeric chain through carboxyl-ate bridges.

Poly[[µ-ethane-1,2-diyl bis-(pyridine-3-carboxyl-ate)](µ-tetra-fluorido-borato)silver(I)].

In the title compound, [Ag(BF(4))(C(14)H(12)N(2)O(4))](n), the coordination of the Ag(+) ion is trigonal-bipyramidal with the N atoms of two ethane-1,2-diyl bis-(pyridine-3-carboxyl-ate) ligands in the apical positions and three F atoms belonging to different tetra-fluorido-borate anions in the equatorial plane. The material consists of infinite chains of [Ag(C(14)H(12)N(2)O(4))] units running along [001], held together by BF(4) (-) bridging anions.

4',5-Dihy-droxy-7-meth-oxy-flavanone dihydrate.

The title compound, C(16)H(14)O(5)·2H(2)O [systematic name: 5-hy-droxy-2-(4-hy-droxy-phen-yl)-7-meth-oxy-chroman-4-one dihydrate], is a natural phytoalexin flavone isolated from the native chilean species Heliotropium taltalense and crystallizes with an organic mol-ecule and two water mol-ecules in the asymmetric unit. The 5-hy-droxy group forms a strong intra-molecular hydrogen bond with the carbonyl group, resulting in a six-membered ring. In the crystal, the components are linked by O-H⋯O hydrogen bonds, forming a three-dimensional network. The 4-hy-droxy-phenyl benzene ring is bonded equatorially to the pyrone ring, which adopts a slightly distorted sofa conformation. The title compound is the hydrated form of a previously reported structure [Shoja (1990 ▶). Acta Cryst. C46, 1969-1971]. There are only slight variations in the mol-ecular geometry between the two compounds.

1-(2,4-Difluoro-phen-yl)-2-(1H-1,2,4-triazol-1-yl)ethanol.

In the title compound, C(10)H(9)F(2)N(3)O, the dihedral angle between the mean planes of the triazole and benzene rings is 20.6 (2)°. In the crystal, mol-ecules are linked by strong O-H⋯ N hydrogen bonds into chains with graph-set notation C(9) along [100]. Weak C-H⋯N and C-H⋯F inter-actions are also observed.

Optic neuritis after COVID-19 vaccine application.

As the COVID-19 pandemic continues to rise, the development of effective vaccines is of crucial importance to prevent further morbidity and mortality. In parallel, some rare adverse events related to COVID-19 vaccines, have been reported, most of them mild. Here we report the case of a previously healthy 19-year-old woman who developed optic neuritis 1 week after single dose of Ad26.COV2.S vaccine with marked improvement after management with steroids. Although causality cannot be confirmed due to lack of a biological marker, this case may help to guide further research for potential pathogenic mechanism.

A monoclinic modification of propane-1,3-diyl bis-(pyridine-3-carboxyl-ate).

In the title compound, C(15)H(14)N(2)O(4), (I), the mol-ecule lies on a twofold rotation axis which passes through the central C atom of the aliphatic chain, giving one half-mol-ecule per asymmetric unit. The structure is a monoclinic polymorph of the triclinic structure previously reported [Brito, Vallejos, Bolte & López-Rodríguez (2010). Acta Cryst. E66, o792], (II). The most obvious difference between them is the O/C/C/C-O/C/C/C torsion angle [58.2 (7)° in (I) and 173.4 (3)/70.2 (3)° in (II) for GG and TG conformations, respectively]. Another important difference is observed in the dihedral angle between the planes of the aromatic rings [86.49 (7)° for (I) and 76.4 (3)° for (II)]. The crystal structure features a weak π-π inter-action [centroid-centroid distance = 4.1397 (10)Å]; this latter kind of inter-action is not evident in the triclinic polymorph.

Propane-1,3-diaminium bis-(pyridine-4-carboxyl-ate) monohydrate.

The asymmetric unit of the title compound, C(3)H(12)N(2) (2+)·2C(6)H(4)NO(2) (-)·H(2)O, consists of half of a doubly protonated propane-1,3-diammonium dication, a pyridine-4-carboxyl-ate anion and half of a solvent water mol-ecule; the dication and the solvent water are located on a twofold rotation axis which passes through the central C atom of the dication and the water O atom. The carboxyl-ate group of the anion appears to be delocalized on the basis of the C-O bond lengths. In the crystal, the components are linked by inter-molecular N-H⋯O, N-H⋯N and O-H⋯O hydrogen bonds.

Diaqua-bis-(5-methyl-pyrazine-2-carboxyl-ato-κN,O)cadmium.

In the title compound, [Cd(C(6)H(5)N(2)O(2))(2)(H(2)O)(2)], the Cd(II) ion is coordinated in a severely distorted octa-hedral geometry. The N atoms are cis to each other, while the water O atoms and ligand O atoms are mutually trans. The crystal structure is stabilized by a network of O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds and π-π stacking inter-actions [centroid-centroid distances = 3.730 (3) and 3.652 (3) Å] between the 5-methyl-pyrazine-2-carboxyl-ate ligands. The structure is isotypic with the manganese analog.

4-[3-(Isonicotino-yloxy)propoxycarbon-yl]pyridinium diiodidoargentate(I).

The structure of the title compound, (C(15)H(15)N(2)O(4))[AgI(2)], consists of an organic 4-[3-(isonicotino-yloxy)propoxycarbon-yl]pyridinium cation which has a gauche-gauche (O/C/C/C-O/C/C/C or GG') conformation and lies on a twofold rotation axis, which passes through the central C atom of the aliphatic chain, and an inorganic [AgI(2)](-) anion. In the complex anion, the Ag(+) cation is bound to two I(-) anions in a linear geometry. The anion was modelled assuming disorder around a crystallographic inversion centre near the location of the Ag(+) cation. The crystal packing is stabilized by a strong inter-molecular N-H⋯N hydrogen bond, which links the cations into zigzag chains with graph-set notation C(16) running along the face diagonal of the ac plane. The N-bound H atom is disordered over two equally occupied symmetry-equivalent sites, so that the mol-ecule has a pyridinium ring at one end and a pyridine ring at the other.

S-(4-Nitrophenyl) 4-nitrobenzenethiosulfonate.

The title compound, C(12)H(8)N(2)O(6)S(2), (I), is a positional isomer of S-(2-nitrophenyl) 2-nitrobenzenethiosulfonate [Glidewell, Low & Wardell (2000). Acta Cryst. B56, 893-905], (II). The most obvious difference between the two isomers is the rotation of the nitro groups with respect to the planes of the adjacent aryl rings. In (I), the nitro groups are only slightly rotated out of the plane of the adjacent aryl ring [2.4 (6) and 6.7 (7) degrees ], while in (II) the nitro groups are rotated by between 37 and 52 degrees , in every case associated with S-S-C-C torsion angles close to 90 degrees . Other important differences between the isomers are the C-S-S(O(2))-C torsion angle [78.39 (2) degrees for (I) and 69.8 (3) degrees for (II) (mean)] and the dihedral angles between the aromatic rings [12.3 (3) degrees for (I) and 28.6 (3) degrees for (II) (mean)]. There are two types of C-H...O hydrogen bond in the structure [C...O = 3.262 (7) A and C-H...O = 144 degrees ; C...O = 3.447 (7) A and C-H...O = 166 degrees ] and these link the molecules into a two-dimensional framework. The hydrogen-bond-acceptor properties differ between the two isomers.