Structures and Stabilities of Doubly-charged (MgO)nMg2+ (n=1-29) Cluster Ions

Ab initio perturbed ion plus polarization calculations are reported for doubly-charged nonstoichiometric (MgO)nMg2+ (n=1-29) cluster ions. We consider a large number of isomers with full relaxations of the geometries, and add the correlation correction to the Hartree-Fock energies for all cluster sizes. The polarization contribution is included at a semiempirical level also for all cluster sizes. Comparison is made with theoretical results for neutral (MgO)n clusters and singly-charged alkali-halide cluster ions. Our method is also compared to phenomenological pair potential models in order to asses their reliability for calculations on small ionic systems. The large coordination-dependent polarizabilities of oxide anions favor the formation of surface sites, and thus bulklike structures begin to dominate only after n=24. The relative stabilities of the cluster ions against evaporation of a MgO molecule show variations that are in excellent agreement with the experimental abundance spectra.Comment: Final version accepted in Journal of Chemical Physics; 8 pages plus 8 figures (6 GIFs and 2 PSs). The main difference with respect to the original submission is the inclusion of coordination-dependent polarizabilities for oxide anions. That results in substantial changes in the result

Multicomponent fluids of hard hyperspheres in odd dimensions

Mixtures of hard hyperspheres in odd space dimensionalities are studied with an analytical approximation method. This technique is based on the so-called Rational Function Approximation and provides a procedure for evaluating equations of state, structure factors, radial distribution functions, and direct correlations functions of additive mixtures of hard hyperspheres with any number of components and in arbitrary odd-dimension space. The method gives the exact solution of the Ornstein--Zernike equation coupled with the Percus--Yevick closure, thus extending to arbitrary odd dimension the solution for hard-sphere mixtures [J. L. Lebowitz, Phys.\ Rev.\ \textbf{133}, 895 (1964)]. Explicit evaluations for binary mixtures in five dimensions are performed. The results are compared with computer simulations and a good agreement is found.Comment: 16 pages, 8 figures; v2: slight change of notatio

Cristalización de (Sr,Ca)CO, en sistemas difusión-reacción

Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Structural and morphological evolution of powders nanostructured ceramics: transitional aluminas

This work aims with the study of the transformation of boehmite into transitional aluminas. Boehmite was obtained by a sol-gel method from an aluminium hazardous waste. The thermal behaviour of boehmite was followed by thermogravimetry and differential thermal analysis to determine the transformation temperatures.  By calcinations of boehmite at temperatures ranging between 250-1000ºC, transitional aluminas (?, ? , ?-Al2O3)  were synthesized and characterized by XRD, TEM and FTIR. All the transitional aluminas exhibit nanometric crystallite size, ranging from 2.5-15nm. ?-Al2O3 was obtained as a nanostructured material at 500ºC with a cell parameter a=7.923Å. ?-phase stars to appear at 850ºC with a crystallite size of 6nm and cell parameters a=5.672Å and c=24.600Å. For ?-Al2O3 the cell parameters, in Å, were a=11.817, b=2.912, c=5.621 and ?=103.8º. The progressive conversion of the transitional phase ?-Al2O3 into the stable polymorph ?-alumina, takes place gradually and a four-phases region is achieved at 1000ºC, where coexist with other transitional phase such as  ?- and ?-Al2O3

A Meiotic Checkpoint Alters Repair Partner Bias to Permit Inter-sister Repair of Persistent DSBs

Accurate meiotic chromosome segregation critically depends on the formation of inter-homolog crossovers initiated by double-strand breaks (DSBs). Inaccuracies in this process can drive aneuploidy and developmental defects, but how meiotic cells are protected from unscheduled DNA breaks remains unexplored. Here we define a checkpoint response to persistent meiotic DSBs in C. elegans that phosphorylates the synaptonemal complex (SC) to switch repair partner from the homolog to the sister chromatid. A key target of this response is the core SC component SYP-1, which is phosphorylated in response to ionizing radiation (IR) or unrepaired meiotic DSBs. Failure to phosphorylate (syp-16A) or dephosphorylate (syp-16D) SYP-1 in response to DNA damage results in chromosome non-dysjunction, hyper-sensitivity to IR-induced DSBs, and synthetic lethality with loss of brc-1BRCA1. Since BRC-1 is required for inter-sister repair, these observations reveal that checkpoint-dependent SYP-1 phosphorylation safeguards the germline against persistent meiotic DSBs by channelling repair to the sister chromatid.Cancer Research UK FC0010048UK Medical Research Council FC0010048Wellcome Trust FC0010048Ministerio de Economía y Competitividad BFU2016-75058-PEuropean Research Council ERC2014 AdG669898 TARLOO

El acceso a los servicios de salud bucodental para la población adulta mayor en la red hospitalaria pública de Medellín (Colombia)

Antecedentes/Objetivos: La población adulta mayor es un grupo poblacional significativo teniendo en cuenta los cambios demográficos de las últimas décadas. En el país y en la ciudad de Medellín, este grupo presenta alta vulnerabilidad social, así mismo se observan necesidades en salud bucal, descritas en los estudios nacionales y regionales en el tema. Aunque se han realizado investigaciones que tratan de identificar determinantes que afectan el acceso y la utilización de los servicios de salud, los estudios en salud bucal son más escasos y en especial en la población adulta mayor. Objetivo: identificar barreras y facilitadores de acceso a los servicios de salud bucal en población adulta mayor atendida en la red hospitalaria pública de Medellín desde la perspectiva del personal de salud. Métodos: Estudio cualitativo. Se realizaron 34 entrevistas semiestructuradas en personal que presta servicios de salud en la red Metrosalud de Medellín. Se identificaron barreras y facilitadores según el modelo de Tanahashi sobre cobertura en los servicios de salud a través de 4 categorías: disponibilidad (D), accesibilidad (A), aceptabilidad (P) y contacto con el servicio (C). Se utilizó la herramienta informática AtlasTi. Resultados: Se identificaron barreras relacionadas con: dificultades en la implementación de políticas sociales debido a que la salud bucal no es una prioridad; se han priorizado otras poblaciones para dar atención en salud bucal y existe insuficiente recurso humano para prestar los servicios de salud (D); la situación de discapacidad de los adultos mayores (A); aspectos educativos, culturales y de género (P); y la crisis del sector salud como una barrera estructural del sistema (C). En cuanto a los facilitadores se mencionan: la existencia de programas que facilitan la demanda inducida a programas de salud bucal y de mecanismos para hacer valer los derechos en salud a través de instancias gubernamentales y otras (D); la ubicación de las unidades y centros de salud en zonas de fácil acceso (A); la capacidad de los profesionales para atender esta población (P) y la articulación de la odontología con otras áreas (C). Conclusiones: Se identificaron determinantes que afectan el acceso a servicios sanitarios en la población adulta mayor, por lo que se requieren estrategias para mejorar la calidad de la atención en salud bucal en este grupo socialmente vulnerable.E.S.E Metrosalud. Medellín (Código: C02-E11-L3-01)

Normal response to tibial neurodynamic test in asymptomatic subjects

BACKGROUND: The straight leg raise test (SLR) is one of the most performed physical tests for mechanosensitivity and impairment of the nervous system. According to the anatomy of the tibial nerve, ankle dorsiflexion and eversion movements could be used to perform the tibial neurodynamic test (TNT). To date, no study has documented the normal responses of the TNT. OBJECTIVE: To document normal responses of the TNT in asymptomatic individuals and to investigate influences from sex and leg dominance. METHODS: A cross-sectional study with 44 asymptomatic volunteer subjects, a total of 88 lower limbs, was carried out. The range of motion (ROM), quality, and distribution of sensory responses were recorded. The hip flexion ROM was measured when subjects reported an intensity of their symptoms of 2/10 (P1) and 8/10 (P2). RESULTS: The mean ROM for hip flexion at P1 was 44.22 ± 13.13 and 66.73 ± 14.30 at P2. Hip flexion was significantly greater at P2 than P1 (p 0.05). The descriptor of the quality of sensory responses most often used by participants was stretching (88.6% and 87.5% for P1 and P2, respectively) in the popliteal fossa and posterior calf. CONCLUSIONS: This study describes the sensory responses of asymptomatic subjects resulting from the TNT. Our findings indicate that TNT responses are independent of the influence of sex or leg dominance

Siguiendo el hilo: ensamble camélidos-humanos-textiles: Una mirada multiescalar y multitemporal

From a perspective akin to the New materialism field, our analysis is more interested in the textile materialization processes, rather than their materiality. This entails an understanding of the fibers in their fluid condition, as a material that is constantly developing and in permanent dialogue, through mediation networks, with humans and other-than-humans. We intend to assemble, under a common perspective, different methodological approaches that are generally not articulated in research, as well as different scales of perception of the material. A multitemporal vision is included, which seeks to rescue the persistent points and connections between different pasts. These proposals were applied to depositional pre-Hispanic contexts belonging to a sector of Puna de Antofagasta de la Sierra (NW of Catamarca, Argentina). The textile pieces under analysis display particular space-time associations, which refer to the 6th-7th and 14th-15th centuries of the Christian Era, approximately.Desde una perspectiva afín a los Nuevos Materialismos, proponemos un análisis que se interesa por los procesos de materialización textil, más que por su materialidad. Esto significa entender las fibras en su condición fluida, como un material en constante proceso de desarrollo y en permanente diálogo, a través de redes de mediación, con humanos y otros-que humanos. Pretendemos ensamblar, bajo una misma perspectiva, distintas aproximaciones metodológicas que generalmente no suelen articularse en las investigaciones, así como diferentes escalas de percepción de lo material. Se suma una mirada multitemporal, que busca rescatar los puntos persistentes y las conexiones entre distintos pasados. Estos planteos se aplicaron a contextos depositacionales prehispánicos que refieren a un sector de la Puna de Antofagasta de la Sierra (NO de Catamarca, Argentina). Las piezas textiles analizadas presentan asociaciones espacio-temporales particulares, que remiten a los siglos VI-VII y XIV-XV aproximadamente

Dietary supplemental plant oils reduce methanogenesis from anaerobic microbial fermentation in the rumen

Ruminants contribute to the emissions of greenhouse gases, in particular methane, due to the microbial anaerobic fermentation of feed in the rumen. The rumen simulation technique was used to investigate the effects of the addition of different supplemental plant oils to a high concentrate diet on ruminal fermentation and microbial community composition. The control (CTR) diet was a high-concentrate total mixed ration with no supplemental oil. The other experimental diets were supplemented with olive (OLV), sunflower (SFL) or linseed (LNS) oils at 6%. Rumen digesta was used to inoculate the fermenters, and four fermentation units were used per treatment. Fermentation end-products, extent of feed degradation and composition of the microbial community (qPCR) in digesta were determined. Compared with the CTR diet, the addition of plant oils had no significant (P > 0.05) effect on ruminal pH, substrate degradation, total volatile fatty acids or microbial protein synthesis. Gas production from the fermentation of starch or cellulose were decreased by oil supplementation. Methane production was reduced by 21–28% (P < 0.001), propionate production was increased (P < 0.01), and butyrate and ammonia outputs and the acetate to propionate ratio were decreased (P < 0.001) with oil-supplemented diets. Addition of 6% OLV and LNS reduced (P < 0.05) copy numbers of total bacteria relative to the control. In conclusion, the supplementation of ruminant diets with plant oils, in particular from sunflower or linseed, causes some favorable effects on the fermentation processes. The addition of vegetable oils to ruminant mixed rations will reduce methane production increasing the formation of propionic acid without affecting the digestion of feed in the rumen. Adding vegetable fats to ruminant diets seems to be a suitable approach to decrease methane emissions, a relevant cleaner effect that may contribute to alleviate the environmental impact of ruminant production

Heterogeneous Photocatalytic Degradation of Ibuprofen Over TiO2–Ag Supported on Activated Carbon from Waste Tire Rubber

In recent years it has been discovered that some common use medicines, such as ibuprofen and other nonsteroidal anti-inflammatory drugs, are found in water sources in concentrations that have the potential to affect aquatic organisms. On the other hand, waste used tires are a massive problem for the environment due to the leaching of toxic compounds to soils and water. Also, the exposition to environmental conditions can make them sources of vectors like mosquitoes. In this work, three activated carbon (AC) catalysts derived from waste tire rubber, titanium dioxide and silver were synthesized using the sol–gel method. Morphological characterizations such as SEM and TEM were performed in which, the agglomeration of titanium particles and silver crystals on the surface of the AC is evident. In the XRD analysis, the presence of elemental silver nanoparticles was detected. In the diffuse reflectance spectroscopy analysis, the decrease in the titanium band gap, as well as activity in the visible spectrum, was observed. The photocatalytic tests were performed at pH 3 and 7 in the presence of UV/Vis radiation. These tests show that there are differences between the catalyst in both, UV and visible regions. Adsorption is a major phenomenon for the removal of ibuprofen, followed by photolytic decomposition. In visible spectra, the catalysts show a good performance for the removal of ibuprofen