Cuantificación del balance en la posición de pie en una población de adultos mayores y niños chilenos

Objective: To quantify the differences in the trajectory of the center of pressure (COP) in an elderly population and a group of children. Methods: This was a cross-section study for which a convenience sample of 38 elderly adults and 20 children was obtained. The parameters studied were: area and average speed of excursion of the COP, and the frequency bands (0.0625; 0.125; 0.25; 0.5; 1, 2 y 4 Hz). Results: During the standing balance evaluation in the absence of the visual system, there are significant differences in the area and average velocity of the COP. The group of children generates much more area of COP during the test than the elder group (p = 0.009). However, postural adjustments in children are faster than those of the older group (p = 0.002). Conclusions: In the absence of the visual system, the elderly group had lower area and speed of postural adjustment than the younger group. The latter group used the vestibular and somatosensory systems to maintain standing balance

Theoretical-methodological proposal for a critical and complex discourse analysis (CCDA) in the Chilean and Peruvian press. The example of the newspapers "La Cuarta" and "Ajá"

El objetivo de este artículo es proponer un diseño teórico-metodológico para un análisis comparativo, crítico y complejo del discurso entre la prensa de Chile y Perú: noticias publicadas en los diarios La Cuarta y Ajá, respectivamente. Como consecuencia del carácter complejo de las relaciones interculturales entre estos países, como estrategia metodológica, se aplicará una matriz centrada en un Análisis Crítico del Discurso (ACD) periodístico que recoja los resultados concretos de cada una de las noticias recurrentes entre ambos medios. En una segunda etapa, y desde las bases metodológicas del ACD, se propondrá un Análisis Crítico y Complejo del Discurso (ACCD) que habilitará una herramienta comparativa de matriz compleja que permita cotejar las diferencias y semejanzas arrojadas por los periódicos en cuestión.The goal of this article is to propose a theoretical-methodological design in order to develop a comparative, critical, and complex discourse analysis between the Chilean and the Peruvian press: news published in the newspapers “La Cuarta” and “Ajá”, respectively. Due to the complex nature of the intercultural relationships between both countries, a matrix centred on a journalistic CDA will be applied as methodological strategy. This, in turn, will bring together the concrete results of each of the recurrent news in both media. In a second stage, and following the methodological grounds of CDA, a critical and complex discourse analysis (CCDA) will be posed enabling a comparative tool of complex matrix which will allow weighing against the differences and similarities yielded by the aforementioned newspapers

HPM-1: A Pure Silica Chiral Polymorph with Helical Pores

A microporous polymorph of SiO2, HPM-1, has a chiral structure and contains helical pores. The defect-free pure SiO2 composition, which has been previously considered unfeasible for this structure type, bestows a high thermal and hydrothermal stability upon this material.CICYT, project MAT2009-09960 CSIC + Fondo Social Europeo, JAE PreDoc ProgramPeer reviewe

HPM-1: The first pure silica chiral zeolite with helical pores, with potential for asymmetric chemistry applications

Póster presented at XXII Internacional Materials Research Congress that took place in Cancún (México) during 11-15th August 2013.Zeolites are microporous crystalline solids with a wide diversity of properties and applications. Their high commercial impact (catalysts in the petrochemical industry, ecological detergents, adsorbents in the purification and separation of gases, etc) is an important motivation for the development of new zeolitic materials. Since the discovery of the structure of zeolite Beta,1 consisting of an intergrowth of several polymorphs, one of them being chiral, the synthesis of chiral zeolites has been a long-sought goal. A homochiral zeolite (composed exclusively by one ¿hand¿) could potentially be used in asymmetric chemistry applications such as enantioselective catalysis or separations. In the present work we report the first pure silica chiral zeolite with helical pores, HPM-1 (framework type code STW).2, 3 HPM-1 zeolite has interesting potential applications, because its structure presents helical pores with the same handedness in each crystal, opening the possibility to impose enantiometic restrictions at a molecular level. In this way, this new chiral zeolite, HPM-1, could be used as an enantiomerically selective molecular sieve adsorbent. The zeolite synthesis, the physicochemical and optical characterizations and structural analysis of HPM-1 are presented in this work

LA TENTATIVA EN LOS DELITOS CONTRA LA SALUD

Este trabajo de investigación fue elegido por la inquietud que existe sobre la proliferación de los denominados delitos de peligro; siendo que en muchas ocasiones se da un adelantamiento extremo del derecho penal, originándose un crecimiento irracional cada vez mayor de éste; resultando todavía más alarmante que ahora se esté penando su tentativa, específicamente en los delitos contra la salud. Razón por la cual SE causó gran interés en observar la razón de dicha aplicación, ya que, además, aparecen interpretaciones del poder judicial en las que se legitima la punición de estos injustos; así como analizar si dicha interpretación es acorde y loable a la ley penal y a la doctrina; y así determinar si éstas son correctas, o si en cambio no existe un solo sentido, es decir, hay una polisemia. Para así establecer y visualizar la legitimidad de dicha punición y su sustento jurídico. Por todo lo anterior, sobra decir que la investigación resulta por demás inquietante y atractiva. La investigación se inició al observar la necesidad de interpretar los textos jurídicos, a fin de dar sentido a la norma y, así establecer el contenido de los delitos contra la salud y su tentativa, por lo que al respecto el tema fue muy factible, ya que se contó con la información suficiente, lo cual arrojó interesantes resultados, comprobándose así la hipótesis planteada; pues se determinó que efectivamente los delitos contra la salud pertenecen a los delitos de peligro, analizándose también, sus clases, sus penalidades y el bien jurídico protegido. Para así determinar que actualmente la tentativa se está aplicando en el transporte y la venta, de los cuales se realizó el análisis jurídico penal

Structure-direction in the crystallization of ITW zeolites using 2-ethyl-1,3,4-trimethylimidazolium

2-Ethyl-1,3,4-trimethylimidazolium is so far the fifth and largest imidazolium cation able to produce the pure silica zeolite ITW. The crystallization is not direct, but occurs as an in situ transformation from either the chiral HPM-1 (STW) zeolite or the new layered zeolite precursor HPM-2 (preMTF) and results in large interpenetrated crystals with a habit so far unseen in this zeolite. The results of chemical, physicochemical and structural characterization allow us to discuss structure-direction issues. The large cation is occluded intact in the zeolite, causing an expansion of the zeolite volume. The degree of polarization of the Si-O bond is similar to that observed in other as-made ITW zeolites.Financial support from the Spanish CICYT, MAT2012-31759, is acknowledged. AR thanks CSIC and Fondo Social Europeo (EU) for a JAE-predoc fellowship

HPM-2, the layered precursor to zeolite MTF

HPM-2 is a new organosilicate layered material synthesized by the fluoride route using 2-ethyl-1,3,4-trimethylimidazolium. The layers are of a new structural type (denoted mtf) and are held together by strong hydrogen bonds giving rise to a 1H magic angle spinning (MAS) nuclear magnetic resonance (NMR) at around 16 ppm and by Coulombic interactions between silanolates and the organic cations residing in the interlayer space. Upon calcination HPM-2 transforms into the pure silica MTF zeolite by topotactic condensation, a process that is essentially completed at 400 C. Attempts to apply known methods to derive new materials (swelling, delamination, interlayer expansion) are described. In the case of the interlayer expansion reaction, a nonmicroporous dense phase is obtained, which is likely due to an unfavorable disposition of silanols in close couples within each layer. Silanol condensation between the newly incorporated silicon species occurs across the main window producing narrower (6 member ring, 6MR) rather than wider (10MR) windows. © 2013 American Chemical Society.Financial support from the Spanish CICYT, MAT2012-31759, is acknowledged. A.R. thanks CSIC and Fondo Social Europeo (EU) for a JAE-predoc fellowship.Peer Reviewe

Synthesis, Structure and Optical Activity of HPM-1, a Pure Silica Chiral Zeolite

2-Ethyl-1,3,4-trimethylimidazolium is a poor organic structure-directing agent in the synthesis of pure silica zeolites using fluoride as a mineralizer at 150 °C. Under these conditions only ill-crystallized solids are obtained after long hydrothermal treatments (several weeks). It disappoints despite its relatively large size, conformational rigidity, and intermediate hydrophilic/hydrophobic character, attributes which would qualify it as a promising structure-directing agent, according to prior investigations. By raising the crystallization temperature to 175 °C under otherwise identical conditions, crystallization is dramatically accelerated. Depending on the water/silica ratio and crystallization time, two differentmaterials are obtained: the recently reported pure silica polymorph of the chiral STW-type zeolite, HPM-1, and the new layered organosilicate, HPM-2. Prolonged heating transforms these phases into the small-pore ITW-type zeolite, while no signs of the SOF-type zeolite (formally built from the same layers as STW) was found. A complete physicochemical and structural characterization of the as-made chiral HPM-1 zeolite is provided, and the proposed stabilization of this zeolite by polarization of the Si−O bond is supported by the observed deviation from tetrahedrality. HPM-1 is optically active, and a study of several crystallites by Mueller matrix microscopy shows that their optical activity can be individually measured and that this technique could be useful for the assessment of the enantiomeric purity of a microcrystalline powder.Spanish Ministry of Economy and Competitiveness (Projects MAT2009-09960 and MAT2012-31759)Peer reviewe

Benzylimidazolium cations as zeolite structure-directing agents. Differences in performance brought about by a small change in size

Two imidazolium cations containing a benzyl group, 1-benzyl-3- methylimidazolium and 1-benzyl-2,3-dimethylimidazolium, generally produce the large pore zeolite MTW when used as structure directing agents in the synthesis of pure silica zeolites by the fluoride route. When working at low water contents only the smallest of these cations is able to crystallize MFI, a zeolite with crossing medium pore channels. In that case, MFI is metastable towards MTW, but the in situ transformation slows down as the water content is decreased. Structure-direction is discussed in terms of hydrophobicity, flexibility and size of the cations. A conformational analysis shows that the bulkier 1-benzyl-2,3-dimethylimidazolium is slightly more rigid than the smaller 1-benzyl-3-methylimidazolium, and thus could have been expected to depart more easily from crystallizing a default structure such as MTW. The different performance of both cations is investigated by molecular mechanics and the simulations show that the small increase in size brought about by a methyl group at position 2 of the imidazolium ring prevents an adequate sitting of the cation at channel intersections with the imidazolium ring close to the small cavity in which fluoride resides in MFI. The calculated interaction energies help to understand the phase selectivity and time evolution experimentally observed with both cations. © 2013 The Royal Society of Chemistry.Financial support from the Spanish CICYT, MAT2009-09960, is gratefully acknowledged. AR thanks CSIC and Fondo Social Europeo (EU) for a JAE-predoc fellowship. LGH acknowledges the Spanish Minister of Economy and Competitivity for a Juan de la Cierva contract.Peer Reviewe

Host-guest stabilization of a zeolite strained framework: In situ transformation of zeolite MTW into the less dense and more strained ITW

The new organic structure-directing agent 1-ethyl-2,3-dimethylimidazolium, in conjuction with fluoride anions, shows selectivity toward pure silica zeolite ITW. At low water contents this zeolite crystallizes directly, while at higher water contents, the denser and more stable in the absence of occluded species MTW crystallizes first and then transforms in situ into ITW. A detailed physicochemical and structural characterization and a periodic density functional theory analysis are provided, and we show crystallographic and DFT evidence for a significant distortion of the SiO4 tetrahedra, attributable to a polarization of the Si-O bond that helps relax the otherwise strained silica framework. A comparative analysis of five closely related imidazolium cations suggests the importance of both hydrophilicity and conformational flexibility in determining their selectivity as structure-directing agents. © 2013 American Chemical Society.Financial support by the Spanish CICYT (Project Nos. MAT2009-09960 and MAT2012-31759) is gratefully acknowledged. A.R. acknowledges a JAE fellowship from CSIC and Fondo Social Europeo from EU.Peer Reviewe