Mechanisms of nonstoichiometry in HfN_1-<i>x</i>

Density functional theory is used to calculate defect structures that can accommodate nonstoichiometry in hafnium nitride: HfN1-x, 0 ≤ X ≤ 0.25. It is predicted that a mechanism assuming simple distributions of nitrogen vacancies can accurately describe the variation in the experimentally observed lattice parameter with respect to the nitrogen nonstoichiometry. Although the lattice parameter changes are remarkably small across the whole nonstoichiometry range, the variations in the bulk modulus are much greater

Produção de milho e sorgo em várzea.

ECOFISIOLOGIA E FENOLOGIA DAS CULTURAS DO MILHO E DO SORGO (Paulo Regis Ferreira da Silva; Gilber Argenta pag 7-18); NUTRIÇÃO, CORREÇÃO DO SOLO E ADUBAÇÃO (Walkyria Bueno Scivittaro pag 19-26); SISTEMAS DE CULTIVO DE MILHO EM VÁRZEA - PLANTIO DIRETO (Francisco de Jesus Vernetti Junior; Algenor da Silva Gomes pag 27-38); IMPLANTAÇÃO DA LAVOURA DE MILHO (Marilda Pereira Porto; Claudio Alberto Sousa da Silva; José Maria Barbat Parfitt; Silvio Steinmetz pag 39-43); CULTIVARES DE MILHO (Marilda Pereira Porto pag 45-55); MANEJO DA CULTURA DO SORGO (Antonio André Amaral Raupp pag 57-59); DRENAGEM E IRRIGAÇÃO PARA MILHO E SORGO CULTIVADOS EM ROTAÇÃO COM ARROZ IRRIGADO (Claudio Alberto Souza da Silva; José Maria Barbat Partitt pag 61-72); ADEQUAÇÃO DA ÁREA PARA A SEMEADURA DO SORGO E DO MILHO IRRIGADOS POR INUNDAÇÃO (José Barbat Partitt; Claudio Alberto S. da Silva pag 73-76); MANEJO DE PLANTAS DANINHAS NA CULTURA DO MILHO EM TERRAS BAIXAS (André Andres; Aldo Merotto Júnior pag 77-86); INSETOS-PRAGAS DAS CULTURAS DO MILHO E DO SORGO NO AGROECOSSISTEMA DE VÁRZEA (Anderson Dionei Grützmacher; José Francisco da Silva Martins; Uemerson Silva da Cunha pag 87-101); DOENÇAS DAS CULTURAS DO SORGO E DO MILHO (Nely Brancão pag 103-106); SECAGEM E ARMAZENAMENTO DE GRÃOS DE MILHO E DE SORGO NA PROPRIEDADE RURAL (Moacir Cardoso Elias pag 107-146).bitstream/item/84493/1/Documento-74-.pdf; bitstream/item/84479/1/Documento-74-pag-001-018.pdf; bitstream/item/84480/1/Documento-74-pag-019-026.pdf; bitstream/item/84481/1/Documento-74-pag-027-038.pdf; bitstream/item/84482/1/Documento-74-pag-039-043.pdf; bitstream/item/84483/1/Documento-74-pag-045-055.pdf; bitstream/item/84484/1/Documento-74-pag-057-059.pdf; bitstream/item/84485/1/Documento-74-pag-061-072.pdf; bitstream/item/84487/1/Documento-74-pag-073-076.pdf; bitstream/item/84488/1/Documento-74-pag-077-086.pdf; bitstream/item/84489/1/Documento-74-pag-087-101.pdf; bitstream/item/84490/1/Documento-74-pag-103-106.pdf; bitstream/item/84492/1/Documento-74-pag-107-146.pd

Oxygen diffusion in Sr_0.75Y_0.25CoO_2.625: a molecular dynamics study

Oxygen diffusion in Sr0.75Y0.25CoO2.625 is investigated using molecular dynamics simulations in conjunction with an established set of Born model potentials. We predict an activation energy of diffusion for 1.56 eV in the temperature range of 1000-1400 K. We observe extensive disordering of the oxygen ions over a subset of lattice sites. Furthermore, oxygen ion diffusion both in the a-b plane and along the c axis requires the same set of rate-limiting ion hops. It is predicted that oxygen transport in Sr0.75Y0.25CoO2.625 is therefore isotropic

Design of a Guarded Hot Plate for Measuring Thin Specimens of Polymer and Composite Materials

The National Physical Laboratory (NPL) has developed a new design of guarded hot plate apparatus specifically for absolute measurements on thin specimens of medium thermal conductivity materials, such as the polymer composites that are becoming more widely used in aerospace and other advanced manufacturing sectors. Although NPL has an existing measurement facility based on a commercially manufactured apparatus conforming to ASTM E1530, this current facility is not based on an absolute measurement technique and is not able to provide the low measurement uncertainty or flexibility that is increasingly being demanded by industrial users of this NPL service. The target specification for this new NPL guarded hot plate is the measurement of materials with thermal conductivity in the range 0.1–10 W·m−1·K−1 using specimens with thickness of 1–20 mm and over the temperature range −100°C to 250°C. This is achieved using a new design of guarded heater plate and a temperature-controlled environmental chamber. This chamber can be evacuated and specific gases can be introduced, enabling measurements on porous materials under a wide range of environments. It can be used in either a single specimen or a double specimen configuration, and with specimen diameters of either 75 mm or 50.8 mm that is used in many older styles of comparative measurement apparatus. During the commissioning of this new measurements facility, it is planned to investigate various approaches for reducing thermal contact resistance between the specimen and plates. This facility will then provide the flexibility for meeting a wider range of requirements from industrial customers

Irrigação por inundação intermitente para culturas em rotação ao arroz em áreas de várzea do Rio Grande do Sul.

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Drenagem superficial para diversificação do uso de solos de várzea do Rio Grande do Sul.

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Knapping tools in Magdalenian contexts: New evidence from Gough’s Cave (Somerset, UK)

Our knowledge of the recolonization of north-west Europe at the end of the Last Glacial Maximum depends to a large extent on finds from Gough's Cave (Somerset, UK). Ultra-high resolution radiocarbon determinations suggest that the cave was occupied seasonally by Magdalenian hunters for perhaps no more than two or three human generations, centred on 12,600 BP (~14,950-14,750 cal BP). They left behind a rich and diverse assemblage of Magdalenian lithic and osseous artefacts, butchered animal bones, and cannibalised human remains. The faunal assemblage from Gough's Cave is one of the most comprehensively studied from any Magdalenian site, yet new and unexpected discoveries continue to be made. Here, we record previously unrecognized flint-knapping tools that were identified during a survey of the Gough's Cave faunal collection at the Natural History Museum (London). We identified bones used as hammers and teeth manipulated as pressure-flakers to manufacture flint tools. Most of the pieces appear to be ad hoc (single-use?) tools, but a horse molar was almost certainly a curated object that was used over an extended period to work many stone tools. This paper explores how these knapping tools were used to support a more nuanced understanding of Magdalenian stone-tool manufacturing processes. Moreover, we provide a standard for identifying minimally-used knapping tools that will help to establish whether retouchers and other organic stone-working tools are as rare in the Magdalenian archaeological record as current studies suggest

Carbon storage and DNA absorption in allophanic soils and paleosols

Andisols and andic paleosols dominated by the nanocrystalline mineral allophane sequester large amounts of carbon (C), attributable mainly to its chemical bonding with charged hydroxyl groups on the surface of allophane together with its physical protection in nanopores within and between allophane nanoaggregates. C near-edge X-ray absorption fine structure (NEXAFS) spectra for a New Zealand Andisol (Tirau series) showed that the organic matter (OM) mainly comprises quinonic, aromatic, aliphatic, and carboxylic C. In different buried horizons from several other Andisols, C contents varied but the C species were similar, attributable to pedogenic processes operating during developmental upbuilding, downward leaching, or both. The presence of OM in natural allophanic soils weakened the adsorption of DNA on clay; an adsorption isotherm experiment involving humic acid (HA) showed that HA-free synthetic allophane adsorbed seven times more DNA than HA-rich synthetic allophane. Phosphorus X-ray absorption near-edge structure (XANES) spectra for salmonsperm DNA and DNA-clay complexes indicated that DNA was bound to the allophane clay through the phosphate group, but it is not clear if DNA was chemically bound to the surface of the allophane or to OM, or both. We plan more experiments to investigate interactions among DNA, allophane (natural and synthetic), and OM. Because DNA shows a high affinity to allophane, we are studying the potential to reconstruct late Quaternary palaeoenvironments by attempting to extract and characterise ancient DNA from allophanic paleosol