Electronic and phononic properties of the chalcopyrite CuGaS2

The availability of ab initio electronic calculations and the concomitant techniques for deriving the corresponding lattice dynamics have been profusely used for calculating thermodynamic and vibrational properties of semiconductors, as well as their dependence on isotopic masses. The latter have been compared with experimental data for elemental and binary semiconductors with different isotopic compositions. Here we present theoretical and experimental data for several vibronic and thermodynamic properties of CuGa2, a canonical ternary semiconductor of the chalcopyrite family. Among these properties are the lattice parameters, the phonon dispersion relations and densities of states (projected on the Cu, Ga, and S constituents), the specific heat and the volume thermal expansion coefficient. The calculations were performed with the ABINIT and VASP codes within the LDA approximation for exchange and correlation and the results are compared with data obtained on samples with the natural isotope composition for Cu, Ga and S, as well as for isotope enriched samples.Comment: 9 pages, 8 Figures, submitted to Phys. Rev

An anchored retaining wall in CSM

Cutter soil mixing (CSM) is being recently used in Portugal in several applications. This paper describes a solution in cutter soil mixing reinforced with vertical steel profiles IPE270 for a retaining wall with 66 m long and 13 m high constructed in geological formations of landfill materials, Miocene sandy soils and sandstones, with a phreatic level around 8 m depth. This construction is done nearby commercial buildings. The solution is justified against more classical solutions for anchored retaining walls considering the following aspects: feasibility of CSM in the geological and environment conditions, predict behaviour during and post construction, simplicity of construction process, time of construction, economy and quality assurance. Numerical modelling using a commercial program is carried out, based in geotechnical parameters established at the project level, showing a good agreement of the observed data, in terms of horizontal displacements of the wall and also of the safety levels against bending, shear and compression.Malgré l'utilisation du traitement des sols en profondeur dans les dernières décennies, la technique « cutter soil mixing» (CSM) est récemment utilisé au Portugal dans plusieurs applications. Cet article décrit une solution CSM renforcé avec des profilésverticaux IPE270 pour un mur de soutènement avec 66 m de long et 13 m de haut construit dans des formations géologiques de matériaux de remblayage, des formations du Miocène de sols sablonneux et des grès, avec un niveau de nappe phréatique autour de 8 m de profondeur. Cette construction se fait à proximité de bâtiments commerciaux. La solution est justifiéepar rapport aux solutions plus classiques des murs de soutènement ancrés tenant compte des aspects suivants: faisabilité du CSM dans une vaste gamme des conditions géologiques et de l'environnement, prévoir le comportement durant et après construction, simplicité du processus de construction, le temps de construction, l'économie et l'assurance-qualité. Une modélisation numérique au moyen d’un programme commercial est effectuée avec l’utilisation des paramètres géotechniques établis au niveau du projet, montrant une bonne concordance des données observées, en termes de déplacements horizontaux de la paroi, autant que des niveaux de sécurité contre la flexion, le cisaillement et la compression.The authors wish to thank to “Fundação para a Ciência e a Tecnologia” (FCT) for the financial support under the strategic project PEst-OE/ ECI/UI4047/2011. In addition, the authors would like to thank the contribution of Ângelo Pereira

Advanced tools and techniques to add value to soil stabilization practice

The aim of this paper is to demonstrate the advanced tools and techniques used for adding value to the soil stabilization practice. The tools presented involve advanced laboratory tests and modeling using codes and soft computing to evaluate the mechanical behavior of stabilized soils with cement, ranging from short-term to long-term behavior. More precisely, these tools are able to: 1. Predict the mechanical behavior of the stabilized soils over time from data obtained in the early ages saving time in laboratory tests; 2. Predict the mechanical behavior of the stabilized soils over time based on basic parameters of soil type and binder using historical accurate data, avoiding mechanical laboratory tests. 3. Incorporate the serviceability limit state concept in a novel proposal to estimate the design modulus in function of the uniaxial compressive strength and the strain level, making more economic and sustainable geotechnical solutions.This work was supported by FCT—‘‘Fundação para a Ciência e a Tecnologia’’, within ISISE, project UID/ECI/04029/2013 and through the post doctoral Grant fellowship with reference SFRH/BPD/94792/2013. This work was also partly financed by FEDER funds through the Competitivity Factors Operational Programme—COMPETE and by national funds through FCT within the scope of the project POCI-01-0145-FEDER-007633.info:eu-repo/semantics/publishedVersio

EFFECT OF SEASON ON SERUM COPPER AND ZINC CONCENTRATIONS IN CROSSBRED GOATS HAVING DIFFERENT REPRODUCTIVE STATUS UNDER SEMIARID RANGELAND CONDITIONS IN SOUTHERN MEXICO STATE

The effect of season (rainy: RS, and dry: DS) and reproductive status on copper (Cu) and zinc (Zn) concentrations in blood serum of crossbred goats (BW= 36.01 ± 1.59 kg) were studied under semiarid rangeland conditions in Southern Mexico State. Blood samples from 80 crossbred goats were taken each season (RS and DS). The goats were clustered into 10 different groups considering their reproductive status. Concentrations of Cu and Zn in serum were assayed using atomic absorption. Data were analyzed using a general linear model procedure for a completely randomized design and differences among means were examined using a Tukey test. Blood serum concentrations of Cu and Zn were affected by reproductive status and season (P<0.001). In relation to the season, Cu and Zn serum levels were lower in RS than DS (P<0.05). Overall, kidded goats had the highest values (P<0.01) for Cu than other animals in both seasons (RS or DS). Anestrous goats had the lowest concentrations (P<0.01) for Zn during RS, while all goats at their second or more kidding, rearing single or twins, showed the highest concentrations of Zn (P<0.001) in this season. Adult goats in Southern Mexico State showed a deficiency of Cu and Zn, especially during RS. As such, mineral supplements should be provided with respect to these elements in feeding systems for goats under semiarid rangeland conditions in order to evaluate their impact on health and reproduction

Comparative analysis of performance by cows confined in different typologies of compost barns

The compost barn system was designed to be a sustainable alternative housing system for dairy cows. In order to help producers in the region to choose the best type of facility from the point of view of the milk production of the animals, this study compared the productivity of cows confined in an open composting barn with natural ventilation and in a closed composting barn with negative pressure ventilation and evaporative cooling panels. The temperature and relative humidity of the air were monitored, as well as the milk production of the animals housed in the facilities, and THI (Temperature and Humidity Index) were calculated. During the trials, the maximum daily temperatures of the air reached values around 27 °C and the THI remained within the normal range of up to 70. The average productivity remained in the general pattern described in the literature from 23 to 44 kg of milk cow1 day-1 , with lower rates obtained in the closed house. As the variation of the index used to describe the internal environment was not significant, it can be inferred that climatic elements as temperature and air humidity, under the conditions analyzed were not the main factors influencing the productivity rates of dairy cattle. In conclusion, under the analysed conditions the use of a closed barn with negative pressure ventilation is hardly justified as a plant that favoured the productivity of the confined cows

Estudo preliminar da cadeia produtiva do cupuaçu (Theobroma grandiflorum (Willd. ex Spreng.) Schum) no Amazonas.

Caracterização geral da cadeia produtiva do cupuaçu. Setor produtivo. Agregação de valores - Agroindústria. Comercialização. Consumidor final. Análise diagnóstica. Análise prognóstica. Identificação de limitações estruturais e tecnológicas da cadeia produtiva do cupuaçu. Demandas identificadas.bitstream/CPAA-2009-09/10583/1/Doc-17_98.pd

On the nature of long-range contributions to pair interactions between charged colloids in two dimensions

We perform a detailed analysis of solutions of the inverse problem applied to experimentally measured two-dimensional radial distribution functions for highly charged latex dispersions. The experiments are carried out at high colloidal densities and under low-salt conditions. At the highest studied densities, the extracted effective pair potentials contain long-range attractive part. At the same time, we find that for the best distribution functions available the range of stability of the solutions is limited by the nearest neighbour distance between the colloidal particles. Moreover, the measured pair distribution functions can be explained by purely repulsive pair potentials contained in the stable part of the solution.Comment: 6 pages, 5 figure