EVALUATION OF THE ANTIOXIDANT ACTIVITY OF THE FLAVONOIDS ISOLATED FROM HELIOTROPIUM SINUATUM RESIN USING ORACFL, DPPH AND ESR METHODOLOGIES

Indexación: Web of Science; Scielo.The antioxidant capacity has been determined for a number of flavonoid compounds from Heliotropium sinuatum, a plant that grows in arid areas in the north of Chile. The methodologies used were: ORAC(FL) (oxygen radical absorbance capacity - fluorescein), DPPH (2,2-diphenyl-2-picrylhydrazyl) bleaching and electron spin resonance (ESR). These compounds were studied in homogeneous and heterogeneous media. The results showed that the 7-o-methyleriodictiol and 3-o-methylisorhamnetin are those with the highest antioxidant capacity.http://ref.scielo.org/m82cz

Nanostructured micelle nanotubes self-assembled from dinucleobase monomers in water

Despite the central importance of aqueous amphiphile assemblies in science and industry, the size and shape of these nano-objects is often difficult to control with accuracy owing to the non-directional nature of the hydrophobic interactions that sustain them. Here, using a bioinspired strategy that consists of programming an amphiphile with shielded directional Watson–Crick hydrogen-bonding functions, its self-assembly in water was guided toward a novel family of chiral micelle nanotubes with partially filled lipophilic pores of about 2 nm in diameter. Moreover, these tailored nanotubes are successfully demonstrated to extract and host molecules that are complementary in size and chemical affinityFunding from the European Research Council (ERC-Starting Grant 279548 PROGRAM-NANO) and MINECO (CTQ2014-57729-P and CTQ2017-84727-P) is gratefully acknowledged

A Tolman-Bondi-Lemaitre Cell-Model for the Universe and Gravitational Collapse

A piecewise Tolman-Bondi-Lemaitre (TBL) cell-model for the universe incorporating local collapsing and expanding inhomogeneities is presented here. The cell-model is made up of TBL underdense and overdense spherical regions surrounded by an intermediate region of TBL shells embedded in an expanding universe. The cell-model generalizes the Friedmann as well as Einstein-Straus swiss-cheese models and presents a number of advantages over other models, and in particular the time evolution of the cosmological inhomogeneities is now incorporated within the scheme. Important problem of gravitational collapse of a massive dust cloud, such as a cluster of galaxies or even a massive star, in such a cosmological background is examined. It is shown that the collapsing local inhomogeneities in an expanding universe could result in either a black hole, or a naked singularity, depending on the nature of the set of initial data which consists of the matter distribution and the velocities of the collapsing shells in the cloud at the initial epoch from which the collapse commences.Comment: 14 pages, 3 figure

Quantum Multiplexing with the Orbital Angular Momentum of light

The orbital angular momentum, OAM, of photons offers a suitable support to carry the quantum data of multiple users. We present two novel optical setups that send the information of n quantum communication parties through the same free-space optical link. Those qubits can be sent simultaneously and share path, wavelength and polarization without interference, increasing the communication capacity of the system. The first solution, a qubit combiner, merges n channels into the same link, which transmits n independent photons. The second solution, the OAM multiplexer, uses CNOT gates to transfer the information of n optical channels to a single photon. Additional applications of the multiplexer circuits, such as quantum arithmetic, as well as connections to OAM sorting are discussed

Generalisation of the Einstein-Straus model to anisotropic settings

We study the possibility of generalising the Einstein--Straus model to anisotropic settings, by considering the matching of locally cylindrically symmetric static regions to the set of $G_4$ on $S_3$ locally rotationally symmetric (LRS) spacetimes. We show that such matchings preserving the symmetry are only possible for a restricted subset of the LRS models in which there is no evolution in one spacelike direction. These results are applied to spatially homogeneous (Bianchi) exteriors where the static part represents a finite bounded interior region without holes. We find that it is impossible to embed finite static strings or other locally cylindrically symmetric static objects (such as bottle or coin-shaped objects) in reasonable Bianchi cosmological models, irrespective of the matter content. Furthermore, we find that if the exterior spacetime is assumed to have a perfect fluid source satisfying the dominant energy condition, then only a very particular family of LRS stiff fluid solutions are compatible with this model. Finally, given the interior/exterior duality in the matching procedure, our results have the interesting consequence that the Oppenheimer-Snyder model of collapse cannot be generalised to such anisotropic cases.Comment: LaTeX, 24 pages. Text unchanged. Labels removed from the equations. Submitted for publicatio

Aprovechamiento de barros procedentes de central de áridos para la elaboración de piezas cerámicas porosas

Aggregates (gravel and sand) are, after water, the Earth’s second most used natural resource, representing about 50% of all consumed mineral resources. Aggregate production generates a large quantity of waste from the aggregate washing process. This waste is made up of suspended solids – sludge – which has a great environmental impact. It is deposited in huge troughs because of the impossibility of discharging it directly into rivers. Many plants have incorporated decanters and filter presses to separate the solid from the liquid fraction. This paper evaluates the possibility of exploiting the solid fraction (i.e. sludge) in the manufacture of fired clay bricks. The added value of these bricks is, on the one hand, the exploitation of sludge as a currently useless waste product, and on the other, the use of this sludge to enhance the physical and mechanical properties of conventional fired clay bricks.Los áridos son la segunda materia prima más consumida en la Tierra después del agua, representando alrededor del 50% de todos los recursos minerales consumidos. El proceso de elaboración de estos áridos genera una gran cantidad de residuos procedentes de su lavado. Se trata de partículas sólidas en suspensión – lodos – de gran impacto ambiental, que se depositan en grandes charcas ante la imposibilidad de verterlos directamente al rio. Muchas empresas han incorporado decantadores y filtros de prensa para separar la fracción solida de la líquida. El presente trabajo evalúa la posibilidad de utilizar la fracción sólida, es decir el barro, para la fabricación de piezas cerámicas. El valor añadido de estas piezas es por un lado el aprovechamiento del barro como producto residual, que en estos momentos es desechable, y por otro, conseguir que este barro mejore las propiedades físico-mecánicas de la cerámica convencional

Cambios en la comunidad macrofaunística en suelos del vichada (quartzipsammentic haplustox) afectados por las quemas

Se estudiaron, en parcelas experimentales de la región de Marandúa (Víchada, Colombia), los cambios que sufre la comunidad edafofaunistica cuando el suelo es sometido a la acción del fuego. Los grupos taxonómicos, en términos generales, aumentan (39% a causa de la quema; las clases Insecta, Arachnida y Oligochaeta se registraron durante los 16meses de experimentación y bajo los 3 tratamientos aplicados (no quema, quema y quema recurrente); la clase Insecta presentó el mayor incremento de órdenes con cada una de las quemas. El número de individuos disminuyó en un 55% como consecuencia de la primera quema, pero se recuperó e incrementó variedad, durante los 10 meses siguientes a ésta.The changes occurred in soil macrofaunistic community of experimental plots in the region of Marandua (Vichada, Colombia), when the soil way subjected to the action of fire, were studied. In general, there is an increase of taxonomic groups (39%, because of the burning. The Classes Insecta, Arachnida, and Oligochaeta were found during the 16months of experimental work under three treatments (no burning, burning and double burning). The largest increase of Orders was registered in the Class Insecta in each treatment. The total number of individuals decreased (55%, as result of the first burning but, these valúes, presented an increase in number and variety during the following ten months

Fundamentos metodológicos en ciencias: [herramientas de pensamiento para trabajos de investigación]

El objetivo que se persigue con este texto es iniciar al estudiante en el trabajo intelectual serio, objetivo y sistemático, darle los instrumentos de pensamiento correctos para ejecutar las operaciones de interés en sus actividades científicas y, sobre todo, disuadirlo de la idea corrientemente adoptada de que cuando se hace trabajo de investigación, casi todo éste puede ser reducido al uso de técnicas empíricas captadoras y transformadoras de datos, así como a la organización de éstos en esquemas ilustrativos más o menos completos. El presente trabajo, más que original, es el producto de la compilación, adaptación e interpretación del pensamiento, análisis y orientaciones en el ámbito de la filosofía, la epistemología y la metodología de la ciencia, de connotados autores y maestros que contribuyen con la profundidad de sus obras a la formación de un espíritu investigativo entre quienes quieran optar por un trabajo serio, coherente y provechoso el quehacer científico. El texto puede utilizarse a manera de lecturas en forma flexible, pues, aunque presenta una aparente concatenación en su distribución temática a lo largo de cinco capítulos, no describe propiamente la metodología del proceso de investigación, sino que se convierte en cada uno de ellos en una propedéutica de pensamiento según la motivación, el propósito y la disposición de estudio del formando. Esperamos que estas ideas y las intenciones que ellas promueven puedan contribuir a desvanecer en las mentes excesivamente dadas a observar la superficie del mundo perceptible, la ilusión en un ingenuo empirismo como medio adecuado para la compresión de los problemas de la realidad tanto natural como social. Aspiramos, igualmente, a contribuir con este trabajo, y de la mano de quienes nos inspiraron y nos han nutrido con su mente lúcida, su experiencia, y sus autorizados escritos, al desarrollo armónico de las facultades intelectuales del estudiante de ciencias, particularmente en el Departamento de Biología

Spherical Universes with Anisotropic Pressure

Einstein's equations are solved for spherically symmetric universes composed of dust with tangential pressure provided by angular momentum, L(R), which differs from shell to shell. The metric is given in terms of the shell label, R, and the proper time, tau, experienced by the dust particles. The general solution contains four arbitrary functions of R - M(R), L(R), E(R) and r(0,R). The solution is described by quadratures, which are in general elliptic integrals. It provides a generalization of the Lemaitre-Tolman-Bondi solution. We present a discussion of the types of solution, and some examples. The relationship to Einstein clusters and the significance for gravitational collapse is also discussed.Comment: 24 pages, 11 figures, accepted for publication in Classical and Quantum Gravit

Theoretical and Experimental Considerations for Neutrinoless Double Beta Decay

In the rst part of this work we show some theoretical aspects of the generation of the neutrino mass by means of a direct extension of the Standard Model of particles, which include the presence of heavy right-handed neutrinos and large Majorana mass terms. From these two new ingredients, it is possible to nd a mass for the light neutrinos which is naturally of the order of 1 eV or less. The idea is to put these theoretical aspects in the context of the search for neutrino mass values by the study of the signal from the Neutrinoless Double Beta Decay Process (0 ). In the second part, a brief summary is given of the experimental considerations required for the measurement of effective Majorana neutrino mass using (0 ). Measurement strategies and background considerations are introduced and an outline of both active and passive methods is given. Finally, current results are discussed with particular emphasis on the HeidelbergMoscow experiment. This note is based on the presentation given at the CERNCLAF 4th Latin American School on High-Energy Physics