Efectos fisiológicos de la termorregulación en trabajadores expuestos a altas temperaturas en una Siderúrgica en Colombia.

La exposición a altas temperaturas en ambientes laborales conlleva a cambios fisiológicos que se manifiestan como mecanismos de compensación a la alteración del equilibrio homeostático corporal. El propósito del presente estudio fue determinar los cambios y el comportamiento de variables fisiológicas a través de frecuencia cardiaca, densidad urinaria, temperatura corporal y tasa de sudoración, en dos escenarios con condiciones térmicas ambientales diferentes definidas por la exposición (grupo expuesto y no expuesto). Adicional, en dos áreas de trabajo diferentes correspondientes al proceso de fundición del acero, una de ellas, Horno electrico donde se hace la fusión de la chatarra y demás materias primas, obteniendo así el acero liquido, el cual se vuelca en el Horno Cuchara y en este, libre ya de escoria se realiza el afino y ajuste definitivo de la composición química del acero. Objetivos: Identificar la relación de las respuestas fisiológicas a carga física y térmica, comparar las respuestas funcionales registradas en el grupo expuestos y no expuestos y contribuir a la introducción de nuevos indicadores para evaluar carga e intensidad de trabajo con fines de normalización ergonómica. Método: Investigación experimental en una muestra de 30 trabajadores evaluados en dos condiciones ambientales diferentes. La temperatura oral se registró al inicio de la jornada y con intervalos de toma de 3 horas. La frecuencia cardiaca (HR) se registró durante las 8 horas de trabajo continuas con pulsometría. Igualmente, se estimó la sudoración por pérdida de masa corporal entre el inicio y el final de la jornada laboral teniendo en cuenta ingestas y perdidas. El procesamiento estadístico se realizó con el programa SPSS v. 20.0, calculándose medidas de tendencia central y dispersión, prueba de wilconxon para las variables dependientes y correlación para identificar asociaciones. Para todos los cálculos se asumió p <0,05. Resultados: No se observaron diferencias significativas frente a la variación de la frecuencia cardiaca (media y máxima), la tasa de sudoración y la densidad urinaria. A pesar de que no hubo diferencias significativas en la variación de la temperatura corporal en horno cuchara, si se observó una diferencia significativa en el horno eléctrico Conclusión: Aunque no se encontraron diferencias estadísticamente significativas en la mayoría de las variables, es un hecho que la exposición a temperaturas elevadas extremas tiene un impacto en el comportamiento fisiológico del organismo. Futuros estudios deben considerar la posibilidad de estandarizar protocolos que permitan la exposición térmica basada en el perfil particular de cada trabajador.

Modificaciones tecnológicas para mejorar la seguridad y calidad del jamón curado

Se introdujeron varias modificaciones tecnológicas en la elaboración habitual del jamón curado español de cerdo blanco para mejorar su seguridad y calidad, así como para investigar la contribución relativa de los diversos procesos implicados en la calidad sensorial. Las modificaciones introducidas en cada uno de 3 experimentos (a, b, c) fueron: a) inoculación de un cultivo iniciador (CI) en la superficie del producto y el envasado del jamón al vacío durante la etapa de reposo (EV); b) aplicación de una atmósfera modificada con un contenido reducido de oxígeno (AMCRO) (durante la totalidad o la última parte del procesado) en dos procesos que diferían en las humedades relativas aplicadas; c) realización de un estufaje de 4 días a 35ºC y la aplicación repetida de pequeñas cantidades de grasa dorsal líquida sobre la superficie del jamón. En cada experimento, se siguió un diseño experimental de bloques incompletos para bloquear y evaluar el efecto de la materia prima en cada parámetro. La aplicación del CI evitó el crecimiento superficial de hongos, pero modificó el flavor del producto, dando lugar a la aparición de flavores impropios del jamón tradicional, al aumento de la incidencia de la coquera y a la reducción de la intensidad de notas características del mismo como el flavor añejo. Estos efectos fueron debidos a la acción directa del CI pero probablemente también a los cambios que provocó en la superficie del jamón, como la atenuación del "sudado" del jamón. El EV trajo consigo una reducción del crecimiento superficial de mohos; un mayor gradiente de humedad entre el interior y el exterior del jamón; una disminución de la pérdida de peso; un aumento del nitrógeno no proteico y cambios negativos en la textura, aspecto y flavor, como el aumento de la intensidad del velo blanco y del flavor a pienso, el aumento de la incidencia de la coquera y la atenuación del flavor añejo. Estos efectos fueron consecuencia del mayor contenido de humedad a que dio lugar dicha modificación tecnológica, de la potenciación de los efectos negativos del uso del CI, así como a los cambios que provocó en la superficie del jamón. El uso de una ACRO durante todo el proceso provocó un aumento del nitrógeno no proteico, una disminución de la concentración de óxidos de colesterol, un aumento de la intensidad del velo blanco y, en combinación con el uso de humedades relativas bajas, causó una disminución del crecimiento bacteriano y evitó el crecimiento de hongos, levaduras y ácaros en el interior y exterior del jamón y el desarrollo de la coquera. Asímismo, dio lugar a una drástica reducción de la intensidad del flavor del jamón debido a la disminución de la intensidad de la oxidación lipídica. Cuando esta ACRO se aplicó únicamente al final del proceso, se consiguió la eliminación de las formas móviles de los ácaros y la disminución de la intensidad de la coquera y el producto resultante poseía un flavor algo más intenso que aquél sometido a una ACRO durante todo el proceso. El aumento de la temperatura de 25-27 ºC a 35 ºC durante 4 días no tuvo ningún efecto sobre los parámetros estudiados. La aplicación de la grasa líquida en la superficie del jamón evitó el secado excesivo en superficie, previno el desarrollo de la coquera y causó un aumento de la intensidad del flavor añejo y una reducción de la incidencia de notas negativas como el tostado, hechos que indican que la liberación de grasa líquida en el jamón ("sudado") constituye un fenómeno determinante en su calidad sensorial. La materia prima fue el factor que afectó a un mayor número de parámetros.

Eliminación de compuestos causantes de olores mediante adsorbentes/catalizadores obtenidos a partir de lodos de depuradora

El aumento de la cantidad de lodos y las dificultades inherentes a su aplicación agrícola y/o disposición en vertederos, hace necesario encontrar nuevas alternativas para su gestión. A nivel europeo, hoy en día se tiende hacia la aplicación de tratamientos térmicos (incineración, pirólisis y gasificación) que permiten una valoración energética de los lodos, si bien generan un residuo sólido que sigue siendo necesario gestionar. El problema medioambiental provocado por (malos) olores resulta difícil de abordar de una manera genérica, teniendo en consideración la propia naturaleza del olor y sus posibles causas. Los olores en las EDARs son provocados básicamente por la degradación de la materia orgánica en condiciones anaeróbicas y se detectan en todas las operaciones unitarias en diferentes niveles de concentración. Esta tesis incidiendo en ambos aspectos, tiene por objeto investigar la valorización de lodos como materiales precursores de adsorbentes/ catalizadores para la eliminación de olores en el entorno de las EDARs, maximizando la reutilización de los lodos. Para la realización de los experimentos se han seleccionado lodos procedentes de tres EDARs situadas en la región de Girona (SC, SB, SL) que difieren en cuanto al tratamiento de los lodos. Ambas muestras han sido caracterizadas con el fin de determinar las diferencias más importantes en los lodos de partida. Los parámetros de caracterización incluyen el análisis de composición química (análisis elemental e inmediato, determinación contenido en cenizas, medida pH, DRX, FT-IR, SEM / EDX) así como análisis de superficie (adsorción de N2 y CO2). En primer lugar los lodos caracterizados han sido sometidos a diferentes tratamientos térmicos de gasificación y pirólisis y los adsorbentes/ catalizadores obtenidos se han probado como adsorbentes para la eliminación de H2S. Como consecuencia de este estudio, se ha desechado el uso de uno de lodos (SC) puesto que se obtenían resultados muy similares a (SB), a continuación el estudio se centró en el lodo de SL. Con este objetivo se han preparado 12 muestras 6 de ellas pirolizadas y 6 gasificadas en el rango de temperaturas que comprende 600-1100 ºC. Posteriormente las muestras han sido caracterizadas y se ha determinado la capacidad de eliminación (x/M) del H2S. Los resultados muestran que hemos sido capaces de obtener unos materiales que si bien, presentan un bajo desarrollo de porosidad dan lugar a valores de capacidades de eliminación elevados y comparables a carbones y materiales adsorbentes comerciales (Centaur, Sorbalit). Las elevadas eficiencias de eliminación se atribuyen básicamente a la presencia de especies catalíticamente activas tales como los óxidos mixtos de calcio y hierro determinados por DRX en las muestras tratadas térmicamente. El segundo bloque de resultados se centra la mejora de las propiedades texturales de estos materiales adsorbentes. Con este objetivo se llevaron acabo procesos de activación física con CO2 y química con H3PO4 e hidróxidos alcalinos (NaOH y KOH), que hasta el momento no se había probado con este tipo de precursores. Los resultados indican que la activación física (CO2) y química (H3PO4) no son unos buenos métodos para la obtención de adsorbentes altamente porosos con este tipo de materia prima bajo las condiciones probadas, sin embargo la activación con hidróxidos alcalinos da lugar a materiales adsorbentes con superficies específicas de hasta 1600 m2g-1. En el caso de la activación con hidróxidos, tanto el incremento de la relación agente activante/ precursor como el incremento de la temperatura producen un descenso del rendimiento, al mismo tiempo que incrementan el valor de SBET. Los materiales resultantes de la activación con hidróxidos alcalinos se han probado como adsorbentes/ catalizadores para la eliminación de H2S. Los resultados indican que un incremento del área superficial no es indicativo de un aumento de la capacidad de eliminación dada la naturaleza ácida de estos materiales obtenidos. Con el fin de contrarrestar el efecto ácido de estos materiales se han realizado los mismos ensayos añadiendo NaOH al lecho de reacción llegando a valores de x/M de hasta 450 mgg-1. Posteriormente también se han realizado ensayos de eliminación de NH3 con algunas de estas muestras, y los resultados obtenidos de x/M son del orden de carbones activados comerciales. Los materiales adsorbentes obtenidos tras la activación con hidróxidos alcalinos se convierten en materiales muy atractivos para ser utilizados como adsorbentes/ catalizadores de múltiples contaminantes (COVs, Hg...).

Soils of the tropics

The conditions for soil development in the lowland tropics are described, in particular the soil-forming factors, climate, parent material, topography and organisms, and their interactions through time. Of particular importance is the climate of the lowland tropics, which has a major influence on the nature of soil development because of high temperatures and the duration of the periods when the soil is moist. The nature of the parent material is also a major determinant of the nature of the soil. Because soil development has taken place in much of the tropics over long time periods, the soils have distinctive characteristics. Soil-forming processes are described briefly, in particular the nature of the weathering of the inorganic fraction of the soil, and the removal of soluble materials in leaching and the translocation of materials in suspension. Typical soils developed in the humid and seasonally moist tropics are briefly described, and comparisons made between the two most widely used international soil classifications, Soil Taxonomy and World Reference Base for Soil Resources. Some of the other soils found within the tropics are briefly described.

Measurement of ionic calcium, pH and soluble divalent cations in milk at high temperature

Dialysis and ultrafiltration were investigated as methods for measuring pH and ionic calcium and partitioning of divalent cations of milk at high temperatures. It was found that ionic calcium, pH, and total soluble divalent cations decreased as temperature increased between 20 and 80°C in both dialysates and ultrafiltration permeates. Between 90 and 110°C, ionic calcium and pH in dialysates continued to decrease as temperature increased, and the relationship between ionic calcium and temperature was linear. The permeabilities of hydrogen and calcium ions through the dialysis tubing were not changed after the tubing was sterilized for 1h at 120°C. There were no significant differences in pH and ionic calcium between dialysates from raw milk and those from a range of heat-treated milks. The effects of calcium chloride addition on pH and ionic calcium were measured in milk at 20°C and in dialysates collected at 110°C. Heat coagulation at 110°C occurred with addition of calcium chloride at 5.4mM, where pH and ionic calcium of the dialysate were 6.00 and 0.43mM, respectively. Corresponding values at 20°C were pH 6.66 and 2.10mM.

Building integration photovoltaic module with reference to Ghana: using triple junction amorphous silicon

This paper assesses the potential for using building integrated photovoltaic (BIPV) roof shingles made from triple-junction amorphous silicon (3a-Si) for electrification and as a roofing material in tropical countries, such as Accra, Ghana. A model roof was constructed using triple-junction amorphous (3a-Si) PV on one section and conventional roofing tiles on the other. The performance of the PV module and tiles were measured, over a range of ambient temperatures and solar irradiance. PVSyst (a computer design software) was used to determine the most appropriate angle of tilt. It was observed that 3a-Si performs well in conditions such as Accra, because it is insensitive to high temperatures. Building integration gives security benefits, and reduces construction costs and embodied energy, compared to freestanding PV systems. Again, it serves as a means of protection from salt spray from the oceans and works well even when shaded. However, compared to conventional roofing materials, 3a-Si would increase the indoor temperature by 1-2 °C depending on the surface area of the roof covered with the PV modules. The results presented in this research enhance the understanding of varying factors involved in the selection of an appropriate method of PV installation to offset the short falls of the conventional roofing material in Ghana.

Feasibility of using dialysis for determining calcium ion concentration and pH in calcium-fortified soymilk at high temperature

Dialysis was performed to examine some of the properties of the soluble phase of calcium (Ca) fortified soymilk at high temperatures. Dialysates were obtained while heating soymilk at temperatures of 80 and 100 °C for 1 h and 121 °C for 15 min. It was found that the pH, total Ca, and ionic Ca of dialysates obtained at high temperature were all lower than in their corresponding nonheated Ca-fortified soymilk. Increasing temperature from 80 to 100 °C hardly affected Ca ion concentration ([Ca2+]) of dialysate obtained from Ca chloride-fortified soymilk, but it increased [Ca2+] in dialysates of Ca gluconate-fortified soymilk and Ca lactate-fortified soymilk fortified with 5 to 6 mM Ca. Dialysates obtained at 100 °C had lower pH than dialysate prepared at 80 °C. Higher Ca additions to soymilk caused a significant (P≤ 0.05) reduction in pH and an increase in [Ca2+] of these dialysates. When soymilk was dialyzed at 121 °C, pH, total Ca, and ionic Ca were further reduced. Freezing point depression (FPD) of dialysates increased as temperature increased but were lower than corresponding soymilk samples. This approach provides a means of estimating pH and ionic Ca in soymilks at high temperatures, in order to better understand their combined role on soymilk coagulation.

Effect of elevated CO2 and high temperature on seed-set and grain quality of rice

Hybrid vigour may help overcome the negative effects of climate change in rice. A popular rice hybrid (IR75217H), a heat-tolerant check (N22), and a mega-variety (IR64) were tested for tolerance of seed-set and grain quality to high-temperature stress at anthesis at ambient and elevated [CO2]. Under an ambient air temperature of 29 °C (tissue temperature 28.3 °C), elevated [CO2] increased vegetative and reproductive growth, including seed yield in all three genotypes. Seed-set was reduced by high temperature in all three genotypes, with the hybrid and IR64 equally affected and twice as sensitive as the tolerant cultivar N22. No interaction occurred between temperature and [CO2] for seed-set. The hybrid had significantly more anthesed spikelets at all temperatures than IR64 and at 29 °C this resulted in a large yield advantage. At 35 °C (tissue temperature 32.9 °C) the hybrid had a higher seed yield than IR64 due to the higher spikelet number, but at 38 °C (tissue temperature 34–35 °C) there was no yield advantage. Grain gel consistency in the hybrid and IR64 was reduced by high temperatures only at elevated [CO2], while the percentage of broken grains increased from 10% at 29 °C to 35% at 38 °C in the hybrid. It is concluded that seed-set of hybrids is susceptible to short episodes of high temperature during anthesis, but that at intermediate tissue temperatures of 32.9 °C higher spikelet number (yield potential) of the hybrid can compensate to some extent. If the heat tolerance from N22 or other tolerant donors could be transferred into hybrids, yield could be maintained under the higher temperatures predicted with climate change.

Effect of Rht alleles on the tolerance of wheat grain set to high temperature and drought stress during booting and anthesis

Factorial pot experiments were conducted to compare the responses of GA-sensitive and GA-insensitive reduced height (Rht) alleles in wheat for susceptibility to heat and drought stress during booting and anthesis. Grain set (grains/spikelet) of near isogenic lines (NILs) was assessed following three day transfers to controlled environments imposing day temperatures (t) from 20 to 40°C. Transfers were during booting and/or anthesis and pots maintained at field capacity (FC) or had water withheld. Logistic responses (y = c/1+e-b(t -m)) described declining grain set with increasing t, and t5 was that fitted to give a 5% reduction in grain set. Averaged over NIL, t5 for anthesis at FC was 31.7±0.47°C (S.E.M, 26 d.f.). Drought at anthesis reduced t5 by <2°C. Maintaining FC at booting conferred considerable resistance to high temperatures (t5=33.9°C) but booting was particularly heat susceptible without water (t5 =26.5°C). In one background (cv. Mercia), for NILs varying at the Rht-D1 locus, there was progressive reduction in t5 with dwarfing and reduced gibberellic acid (GA) sensitivity (Rht-D1a, tall, 32.7±0.72; Rht-D1b, semi-dwarf, 29.5±0.85; Rht-D1c, severe dwarf, 24.2±0.72). This trend was not evident for the Rht-B1 locus, or for Rht-D1b in an alternative background (Maris Widgeon). The GA-sensitive severe dwarf Rht12 was more heat tolerant (t5=29.4±0.72) than the similarly statured GA-insensitive Rht-D1c. The GA-sensitive, semi-dwarfing Rht8 conferred greater drought tolerance in one experiment. Despite the effects of Rht-D1 alleles in Mercia on stress tolerance, the inconsistency of the effects over background and locus led to the conclusion that semi-dwarfing with GA-insensitivity did not necessarily increase sensitivity to stress at booting and flowering. In comparison to effects of semi-dwarfing alleles, responses to heat stress are much more dramatically affected by water availability and the precise growth stage at which the stress is experienced by the plants.

Compositional control of the electrical transport properties in the new series of thiospinels Ga1-xGexV4S8-delta (0 <=x<=1)

A new series of non-stoichiometric sulfides Ga1−xGexV4S8−δ (0≤x≤1; δ≤0.23) has been synthesized at high temperatures by heating stoichiometric mixtures of the elements in sealed quartz tubes. The samples have been characterized by powder X-ray diffraction, SQUID magnetometry and electrical transport-property measurements. Structural analysis reveals that a solid solution is formed throughout this composition range, whilst thermogravimetric data reveal sulfur deficiency of up to 2.9% in the quaternary phases. Magnetic measurements suggest that the ferromagnetic behavior of the end-member phase GaV4S8 is retained at x≤0.7; samples in this composition range showing a marked increase in magnetization at low temperatures. By contrast Ga0.25Ge0.75V4S8−δ appears to undergo antiferromagnetic ordering at ca. 15 K. All materials with x≠1 are n-type semiconductors whose resistivity falls by almost six orders of magnitude with decreasing Ga content, whilst the end-member phase GeV4S8−δ is a p-type semiconductor. The results demonstrate that the physical properties are determined principally by the degree of electron filling of narrow-band states arising from intracluster V–V interactions.

Study on the application of cool paintings for the passive cooling of existing buildings in Mediterranean climates

Building roofs play a very important role in the energy balance of buildings, especially in summer, when they are hit by a rather high solar irradiance. Depending on the type of finishing layer, roofs can absorb a great amount of heat and reach quite high temperatures on their outermost surface, which determines significant room overheating. However, the use of highly reflective cool materials can help to maintain low outer surface temperatures; this practice may improve indoor thermal comfort and reduce the cooling energy need during the hot season.This technology is currently well known and widely used in the USA, while receiving increasing attention in Europe. In order to investigate the effectiveness of cool roofs as a passive strategy for passive cooling in moderately hot climates, this paper presents the numerical results of a case study based on the dynamic thermal analysis of an existing office building in Catania (southern Italy, Mediterranean area). The results show how the application of a cool paint on the roof can enhance the thermal comfort of the occupants by reducing the operative temperatures of the rooms and to reduce the overall energy needs of the building for space heating and cooling.

Retention at room temperature of the tetragonal t ``-form in Sc(2)O(3)-doped ZrO(2) nanopowders

Synchrotron X-ray powder diffraction was applied to the study of the effect of crystallite size on the crystal structure of ZrO(2)-10 mol% Sc(2)O(3) nanopowders synthesized by a nitrate-lysine gel-combustion route Nanopowders with different average crystallite sizes were obtained by calcination at several temperatures, ranging from 650 to 1200 degrees C The metastable t""-form of the tetragonal phase, exhibiting a cubic unit cell and tetragonal P4(2)/nmc spatial symmetry, was retained at room temperature in fine nanocrystalline powders, completely avoiding the presence of the stable rhombohedral beta phase. Differently, this phase was identified in samples calcined at high temperatures and its content increased with increasing crystallite size The critical maximum crystallite size for the retention of the mestastable t""-form resulted of about 35 nm (C) 2009 Elsevier B.V All rights reserved

High T/P evolution and metamorphic ages of the migmatitic basement of northern Sierras Pampeanas, Argentina: Characterization of a mid-crustal segment of the Famatinian belt

New petrologic, thermobarometric and U-Pb monazite geochronologic information allowed to resolve the metamorphic evolution of a high temperature mid-crustal segment of an ancient subduction-related orogen. The EI Portezuelo Metamorphic-Igneous Complex, in the northern Sierras Pampeanas, is mainly composed of migmatites that evolved from amphibolite to granulite metamorphic facies, reaching thermal peak conditions of 670-820 degrees C and 4.5-5.3 kbar. The petrographic study combined with conventional and pseudosection thermobarometry led to deducing a short prograde metamorphic evolution within migmatite blocks. The garnet-absent migmatites represent amphibolite-facies rocks, whereas the cordierite-garnet-K-feldspar-sillimanite migmatites represent higher metamorphic grade rocks. U-Pb geochronology on monazite grains within leucosome record the time of migmatization between approximate to 477 and 470 Ma. Thus, the El Portezuelo Metamorphic-Igneous Complex is an example of exhumed Early Ordovician anatectic middle crust of the Famatinian mobile belt. Homogeneous exposure of similar paleo-depths throughout the Famatinian back-arc and isobaric cooling paths suggest slow exhumation and consequent longstanding crustal residence at high temperatures. High thermal gradients uniformly distributed in the Famatinian back-arc can be explained by shallow convection of a low-viscosity asthenosphere promoted by subducting-slab dehydration. (C) 2011 Elsevier Ltd. All rights reserved.

Thermochronology of central Ribeira Fold Belt, SE Brazil: Petrological and geochronological evidence for long-term high temperature maintenance during Western Gondwana amalgamation

The studied sector of the central Ribeira Fold Belt (SE Brazil) comprises metatexites, diatexites, charnockites and blastomylonites. This study integrates petrological and thermochronological data in order to constrain the thermotectonic and geodynamic evolution of this Neoproterozoic-Ordovician mobile belt during Western Gondwana amalgamation. New data indicate that after an earlier collision stage at similar to 610 Ma (zircon, U-Pb age), peak metamorphism and lower crust partial melting, coeval with the main regional high grade D(1) thrust deformation, occurred at 572-562 Ma (zircon, U-Pb ages). The overall average cooling rate was low (<5 degrees C/Ma) from 750 to 250 degrees C (at similar to 455 Ma; biotite-WR Rb-Sr age), but disparate cooling paths indicate differential uplift between distinct lithotypes: (a) metatexites and blastomylonites show a overall stable 3-5 degrees C/Ma cooling rate; (b) charnockites and associated rocks remained at T>650 degrees C during sub-horizontal D(2) shearing until similar to 510-470 Ma (garnet-WR Sm-Nd ages) (1-2 degrees C/Ma), being then rapidly exhumed/cooled (8-30 degrees C/Ma) during post-orogenic D(3) deformation with late granite emplacement at similar to 490 Ma (zircon, U-Pb age). Cooling rates based on garnet-biotite Fe-Mg diffusion are broadly consistent with the geochronological cooling rates: (a) metatexites were cooled faster at high temperatures (6 degrees C/Ma) and slowly at low temperatures (0.1 degrees C/Ma), decreasing cooling rates with time; (b) charnockites show low cooling rates (2 degrees C/Ma) near metamorphic peak conditions and high cooling rates (120 degrees C/Ma) at lower temperatures, increasing cooling rates during retrogression. The charnockite thermal evolution and the extensive production of granitoid melts in the area imply that high geothermal gradients were sustained fora long period of time (50-90 Ma). This thermal anomaly most likely reflects upwelling of asthenospheric mantle and magma underplating coupled with long-term generation of high HPE (heat producing elements) granitoids. These factors must have sustained elevated crustal geotherms for similar to 100 Ma, promoting widespread charnockite generation at middle to lower crustal levels. (C) 2010 Elsevier B.V. All rights reserved.

The shoving model for the glass-former LiCl center dot 6H(2)O: A molecular dynamics simulation study

Molecular dynamics (MD) simulations of LiCl center dot 6H(2)O Showed that the diffusion coefficient D, and also I lie structural relaxation time , follow a power law at high temperatures, D(-1) proportional to (T - T(0))(-mu), with the same experimental parameters for viscosity (T(0) = 207 K, mu = 2.08). Decoupling between D and occurs at T(x) similar to 1.1 T(0). High frequency acoustic excitations for the LiCl center dot 6H(2)O model were obtained by the calculation of time correlation functions of mass current fluctuations. The temperature dependence of the instantaneous shear modulus, G,(T), was considered in the shoving model for supercooled liquids [J.C. Dyre, T. Christensen, N.B. Olsen, J. Non-Cryst. Solids 352 (2006) 4635] resulting in a linear relationship log (D(-1)) vs. G root T. (C) 2009 Elsevier B.V. All rights reserved.