Entropy driven key-lock assembly

The effective interaction between a sphere with an open cavity (lock) and a spherical macroparticle (key), both immersed in a hard sphere fluid, is studied by means of Monte Carlo simulations. As a result, a 2d map of the key-lock effective interaction potential is constructed, which leads to the proposal of a self-assembling mechanism: there exists trajectories through which the key-lock pair could assemble avoiding trespassing potential barriers. Hence, solely the entropic contribution can induce their self-assembling even in the absence of attractive forces. This study points out the solvent contribution within the underlying mechanisms of substrate-protein assembly/disassembly processes, which are important steps of the enzyme catalysis and protein mediated transport

Vapor-liquid surface tension of strong short-range Yukawa fluid

The thermodynamic properties of strong short-range attractive Yukawa fluids, k=10, 9, 8, and 7, are determined by combining the slab technique with the standard and the replica exchange Monte Carlo (REMC) methods. A good agreement was found among the coexistence curves of these systems calculated by REMC and those previously reported in the literature. However, REMC allows exploring the coexistence at lower temperatures, where dynamics turns glassy. To obtain the surface tension we employed, for both methods, a procedure that yields the pressure tensor components for discontinuous potentials. The surface tension results obtained by the standard MC and REMC techniques are in good agreement.Comment: 6 pages, 4 figure

Design and performance of ropes for climbing and sailing

Ropes are an important part of the equipment used by climbers, mountaineers, and sailors. On first inspection, most modern polymer ropes appear similar, and it might be assumed that their designs, construction, and properties are governed by the same requirements. In reality, the properties required of climbing ropes are dominated by the requirement that they effectively absorb and dissipate the energy of the falling climber, in a manner that it does not transmit more than a critical amount of force to his body. This requirement is met by the use of ropes with relatively low longitudinal stiffness. In contrast, most sailing ropes require high stiffness values to maximize their effectiveness and enable sailors to control sails and equipment precisely. These conflicting requirements led to the use of different classes of materials and different construction methods for the two sports. This paper reviews in detail the use of ropes, the properties required, manufacturing techniques and materials utilized, and the effect of service conditions on the performance of ropes. A survey of research that has been carried out in the field reveals what progress has been made in the development of these essential components and identifies where further work may yield benefits in the future

A jade pished hand-axe from Tubino's Cection (Valencina de la Concepción Local Museum, Sevilla, Spain)

A pished axe donated to the Valencina de la Concepción Museum (Seville, Spain) in November 2010, and that had belonged to Francisco María Tubino y Oliva's (1833-1888) personal clection, is studied. Although the exact provenance of this object is unknown, there are reasons to think that it might have been found on some archaẽogical site of the Seville province. Through the application of two different analytical techniques (XRD, DCμRS), this axe is identified as a jade-jadeite of purity above 95 ml%, which necessarily implies it came from the Alps. In the conclusions a discussion of this artifact is made in terms of long distance contact in Iberian Late Prehistory.Peer Reviewe

Luminiscence dating of burial 3 and the bell beaker pottery from La Pijotilla (Badajoz, Spain)

La Pijotilla es uno de los mayores asentamientos (80 Ha) del III milenio A.N.E. de la Península Ibérica, siendo considerado un lugar central dentro de la red de poblamiento de Tierra de Barros (comarca de Tierra de Barros, Badajoz). Desde los años 70 se han excavado el poblado y la necrópolis, destacando la tumba T3, excavada en la roca donde se realizaron 300 inhumaciones en capas sucesivas generando una estratigrafía amplia y que contenía un variado y cuantioso ajuar. En el poblado se ha recuperado una colección de fragmentos campaniformes sin contexto estratigráfico, junto a una gran diversidad de estilos decorativos pertenecientes a la última fases del III milenio ANE. El objetivo propuesto en este trabajo ha sido datar diferentes niveles de la tumba T3 y compararlas con otras dataciones C14; al igual que datar la cerámica campaniforme de superficie del poblado y compararla con dataciones absolutas procedentes de contextos habitacionalesLa Pijotilla, one of the largest settlements through out all Iberian Peninsula, and is considered a central place of Tierra de Barros Copper Age settlement network (Comarca de Tierra de Barros, Badajoz). During the field works that has been going on since the 70’s, the settlement and the necropolis area have been located. Several tombs have been excavated, standing out tomb 3, build on the rock with 300 buried individuals and a great richness of funerary objects alternated in several layers. During survey works in the settlement a large amount of decorated pottery from III millennium BC including a great number of Bell Beaker pottery, without a stratigraphic context, have been found. The focus in this work is to date different layers of T3 using luminescence techniques and compare them with old and new radiocarbon dates, as well as to date the survey-collected Bell Beaker pottery and compare them with the settlement radiocarbon datesPlan Nacional de Materiales MAT 2005-000790GRICES-CSIC 2005-PT003

Residencia Sanitaria de la Seguridad Social La Paz

The full details of this project will be described in a later issue of this magazine. It includes the following: sanitary residence, maternity home, children's hospital, and outpatient's department. At present the first and last buildings are completed and in use. The sanitary residence is described below. This building incorporates the experience gained from other similar projects carried out by the State Health Insurance. This is perhaps a unique example in the western world of many health buildings, planned jointly, and built within a short space of time. The design has been inspired by three fundamental ideas, namely, airiness, flexibility and compactness in the space and volume distribution. The planform is a cross of unequal arms, where the central nucleus provides for the vertical circulation system. The organisation and distribution is most modern, and includes all recent advances that can be wished for in this type of building. The total built area, including galleries, boiler rooms, and tower, is 30.878 m² The number of beds is 855, which gives 36.11 m² per bed.<br><br>El complejo total, de próxima inauguración, que será publicado en un futuro número de INFORMES, comprenderá los siguientes cuerpos: Residencia Sanitaria, Maternidad, Traumatología, Hospital infantil y Ambulatorio. En la actualidad se hallan completamente terminados y en uso el primero y el último. Describimos a continuación la Residencia Sanitaria: En este edificio se han resumido las experiencias del conjunto de edificaciones realizadas por el Seguro de Enfermedad. Son un ejemplo, quizás único en Occidente, de construcciones hospitalarias ejecutadas bajo un mismo plan, en un lapso corto de tiempo, y dedicado al mismo fin. En la redacción del proyecto han presidido tres ideas fundamentales: claridad, flexibilidad y concentración, no sólo de espacio, sino también de volúmenes. La planta básica es una cruz de brazos desiguales con un núcleo central de circulaciones verticales. El organigrama, completísimo y con toda suerte de adelantos técnicos e instalaciones complementarias y auxiliares, abarca las máximas exigencias apetecibles en este tipo de edificios. La superficie total construida, incluidas galería, salas de calderas, plantas y torreón, es de 30.878,04 metros cuadrados, y el número real de camas, 855, lo que arroja una superficie por cama de 36,11 metros cuadrados

Datación del recinto murado calcolítico de Las Mesas (La Fuente, España)

El yacimiento amurallado de media hectárea de Las Mesas se ubica en la margen oeste del río Guadiana (La Fuente, Badajoz, España). El análisis de la cultura material recuperada en prospecciones de superficie remite a un arco cronológico que va desde el Neolítico Final (ca. 3600-2900 AC) a la Edad del Cobre (III milenio AC). Las excavaciones han revelado una muralla polibastionada y un espacio habitacional en el centro del asentamiento con tres fases de uso, diferentes áreas funcionales y un hoyo votivo adscrito a la segunda fase. En un hoyo ritual efectuado en la segunda fase se ha recuperado una cornamenta de cérvido que ha sido datado mediante AMS-14C. Se analizaron por Luminiscencia Ópticamente Estimulada (OSL) muestras de un nivel de uso de suelo asignado a la segunda fase (UE-9/10) y de la base de un horno asociado a la primera fase (UE- 18). Se aplicó un procedimiento de Dosis Única Regenerativa (SAR) sobre la fracción de granos de cuarzo de 90-160 μm. Se efectuó también un análisis de 7 muestras tomadas de la estratigrafía para determinar las variaciones de la conducta luminiscente y la edad relativa a través de la secuencia estratigráfica en muestras polimi- nerales mediante luminiscencia estimulada infrarojaópticamente y térmicamente (IRSl, OSL, TSL). La datación y el perfil luminiscente indican que el nivel superior (UE-1B) pertenecería probablemente al Bronce Final (ca. 1000 AC), pero que el resto de la secuencia estratigráfica se corresponde con una ocupación del Neolítico Final-Edad del Cobre. Siendo lo más probable que la ocupación del sitio tuviera lugar entre el 3300 y el 2900 AC. Se detectan vacíos de ocupación entre la fase I y II, y entre la fase II y la ocupación del Bronce Final (fase III). Indicando que el asentamiento fue abandonado y reocupado en dos ocasiones, una en la Edad del Cobre y una en el Bronce Final. La fecha de 4254 ± 45 BP (3010-2675 cal AC) obtenida mediante AMS-14C coincide con las fechas luminiscente de la fase II, apuntando que el hoyo fue excavado al principio de la fase II. Las fechas luminiscentes y radiocarbónicas combinadas muestran que el asentamiento de Las Mesas fue ocupado durante la colonización agrícola del territorio que tuvo lugar en el Neolítico Final, abandonado durante la Edad del Cobre y reocupado en el Bronce Final. Los vacíos poblacionales registrados podrían relacionarse con las evidencias de quemado y destrucción parcial de la muralla del asentamiento, y su posterior reconstrucción y consolidación.The site of Las Mesas is located in the west bank of the Guadajira river (La Fuente, Badajoz, Spain). It covers a half hectare and is enclosed by a stone wall. Previous assessments based on site surveys suggested a general chronological span from Late Neolithic period (ca. 3600- 2900 BC) through the Copper Age (3rd millennium BC). Excavations revealed a well-constructed wall with bastions and a domestic space at the centre of the site with three occupational phases. Several functional areas and a votive pit are ascribed to the second phase. A deer antler located in a re-cut ritual pit associated to the second phase was dated by AMS-14C. Samples from a living floor assigned to the second phase (SU- 9/10) and the basement of a kiln associated with the first phase (SU-18) was dated by optically stimulated luminescence (OSL) using the single aliquot regenerative dose (SAR) protocol on 90-160 μm quartz grains. Luminescence profiling analysis of 7 samples taken throughout the archaeological stratigraphy was used to assess variations in luminescence behaviour and relative age through the sequence, using infrared-, optically –and thermally– stimulated luminescence (IRSL, OSL, TSL) on poly-mineral and etched samples. Luminescence dating and profiling indicates that the upper archaeological layer (SU-1B) probably dates to the Late Bronze Age (ca. 1000 BC), but that the sediments in the remainder of this section accumulated during the late Neolithic-Copper Age: the site was most probably inhabited between 3300 and 2900 BC. There were gaps in occupation between the Late Neolithic-Cooper Age phases (I & II), and between the Late Neolithic-Cooper Age phases and Late Bronze Age phase (II & III), indicating that the site was abandoned and reoccupied twice. The AMS-14C date on deer antler of 4254 ± 45 BP (3010- 2675 cal BC) is consisten with the OSL results for phase II, indicating that the pit was excavated at the beginning of the second occupational phase. Combined OSL and AMS-14C dating shows that Las Mesas site was first occupied during Late Neolithic farming colonization, abandoned during the Copper Age and occupied again during the Late Bronze Age. The occupational gap recorded during the Copper Age relates to evidence for burning of the site and the partial destruction of the wall, followed by its reconstruction and consolidation

Au-supported on Fe-doped ceria solids prepared in water-in-oil microemulsions: Catalysts for CO oxidation

Gold catalysts were synthesized by deposition-precipitation employing Fe-doped ceria systems, previously obtained by means of the water-in-oil microemulsions methodology with different iron contents (10, 25 and 50 Fe at.%). The final catalysts were tested in the CO oxidation reaction in presence of H2. After gold deposition the crystalline structure of the supports was not altered. Moreover no XRD lines associated to gold were detected, indicating its high dispersion. Solid solution was generated in all samples, although the segregation of iron oxide was detected for the material with the highest iron loading. This phenomenon was then enhanced for the corresponding gold catalyst that also presented sintering of the gold nanoparticles. Strong interaction between gold and the oxygen vacancies of the supports was demonstrated, as well as the promotion of the reducibility of surface Ce4+ and Fe3+ species at low temperatures. A remarkable promotion of the CO conversion at lower temperatures respect to that of the supports was observed for the gold catalysts. Below 120 °C, lower the amount of iron incorporated, higher the catalytic performance of the catalyst. This behaviour is closely related not only to a high gold dispersion but also to the ability for creating additional oxygen vacancies in the support, required for the CO oxidation reaction

Fe-doped ceria solids synthesized by the microemulsion method for CO oxidation reactions

A series of Ce-Fe mixed oxides as well as the pure oxides were synthesized by the microemulsions method. The solid solution formation was established for all the Fe-doped systems and only a hardly noticeable segregation of α-Fe2O3 was appreciated for the solid with the maximum iron content (50at.% Fe). The oxygen exchange is improved for all the Fe-doped systems; however the 10at.% Fe appears as the optimal iron content for achieving the maximum oxygen vacancies concentration and the higher reducibility efficiency. The CO oxidation (TOX, PROX) is especially achieved for the solids with the lower iron contents but with a superior oxygen vacancies proportion. These Ce-Fe systems prepared from microemulsions are very attractive to be considered as supports for depositing active phases capable of enhancing oxygen exchange ability of the whole system, allowing higher CO oxidation abilities.Ministerio de Ciencia e Innovación ENE2009-14522-C05-01Junta de Andalucía P09-TEP-545