Production and nutritional composition of two annual ryegrass cultivars (Diploid and Tetraploid)

The feed cost represents the major cost in milk production. Direct grazing and forage produced on the dairy farm could allow the farmer to a better feed production cost control. Ryegrass have been extensively used for grazing and forage production. This study evaluates the production and nutritional composition of two ryegrass cultivars diploid and tetraploid alone or in a binary mixture (50:50). The results showed that the binary mixture is a good option because of its higher production of DM/ha, higher ME and NFC and lower content of NDF, ADF and ADL.info:eu-repo/semantics/publishedVersio

Produção de azevém anual : diploide e tetraploide em monoculturas e mistura binária.

A produção de leite em Portugal atravessa momentos difíceis. O preço pago aos produtores é um dos mais baixos da UE tendo atingido em julho de 2018 0,3007 €/kg, menos 2,77 cêntimos do que o valor médio pago aos produtores europeus no mesmo mês (0,3284 €/kg) (MMO, 2018). Os custos de alimentação da vaca leiteira têm um peso importante na formação do preço do leite. Representam 50% e 78,4% do custo total da produção de leite (Alqaisi et al., 2011; Baptista et al., 2012; Sottomayor et al., 2012). Isto significa que para aumentar a rentabilidade da exploração é fundamental reduzir os custos com a alimentação satisfazendo as necessidades nutricionais dos animais utilizando mais forragens produzidas na exploração. Regimes alimentares baseados no pastoreio ou na utilização de forragens produzidas na própria exploração são economicamente mais interessantes do que regimes baseados na utilização de concentrados cujo preço o produtor não controla (Alqaisi et al., 2011). O azevém tem sido uma das forragens mais utilizadas na alimentação de vacas leiteiras (Wilson e McDowall, 1966; Tas, 2006; Cooke et al, 2008; Cooke et al, 2009). Esta forragem pode ser fornecida em pastoreio direto, em feno, feno-silagem, silagem ou em regimes mistos com pastoreio e conservação. Também em Portugal, o azevém anual é muito utilizado na formulação de regimes alimentares para vacas leiteiras e a influência favorável que esta forragem tem sobre a composição do leite em ácidos gordos (CLA, ácido linoleico e ácido α-linolénico) é demostrada num artigo de revisão (Kalač e Samková, 2010). Assumindo a importância que o azevém tem na produção leiteira em Portugal pretendeu-se avaliar a produção e a composição nutricional de duas variedades cultivadas em monocultura ou em mistura binária em condições características de um clima Termomediterrânico.info:eu-repo/semantics/publishedVersio

Quantum molecular dynamics simulations of conjugated polymers

The softness of conjugated polymers leads to strong coupling between polymer's electrons and lattice vibrations. Therefore, it is necessary to perform quantum molecular dynamics computer simulations in order to study their electronic and optical properties at molecular level. We have used self-consistent molecular dynamics calculations with interatomic forces evaluated from quantum mechanical calculations at the complete neglect of differential overlap level to discuss some of the issues relating to the electronic processes involved in polydiacetylene and poly(p-phenylene vinylene). Specifically addressed are the charge induced structural changes of the polymer chains and the intra-molecular charge mobility. The change in the chemical potential of individual polymer strands at zero temperature is also discussed. Our results suggest a geometrical distortion in the bond length distribution relative to the uncharged chains which is accompanied by changes in atomic charges at the distortion site. The charge carrier mobility is predicted to depend on the strength of the electric field, in accordance with experiments

Symplectic evolution of Wigner functions in markovian open systems

The Wigner function is known to evolve classically under the exclusive action of a quadratic hamiltonian. If the system does interact with the environment through Lindblad operators that are linear functions of position and momentum, we show that the general evolution is the convolution of the classically evolving Wigner function with a phase space gaussian that broadens in time. We analyze the three generic cases of elliptic, hyperbolic and parabolic Hamiltonians. The Wigner function always becomes positive in a definite time, which is shortest in the hyperbolic case. We also derive an exact formula for the evolving linear entropy as the average of a narrowing gaussian taken over a probability distribution that depends only on the initial state. This leads to a long time asymptotic formula for the growth of linear entropy.Comment: this new version treats the dissipative cas

Poincare's Recurrence Theorem and the Unitarity of the S matrix

A scattering process can be described by suitably closing the system and considering the first return map from the entrance onto itself. This scattering map may be singular and discontinuous, but it will be measure preserving as a consequence of the recurrence theorem applied to any region of a simpler map. In the case of a billiard this is the Birkhoff map. The semiclassical quantization of the Birkhoff map can be subdivided into an entrance and a repeller. The construction of a scattering operator then follows in exact analogy to the classical process. Generically, the approximate unitarity of the semiclassical Birkhoff map is inherited by the S-matrix, even for highly resonant scattering where direct quantization of the scattering map breaks down.Comment: 4 latex pages, 5 ps figure

Development of sulfur based polymers for rechargeable lithium batteries

Lithium-ion (Li-ion) batteries are in the front edge of recent achievements concerning energy storage. However, Li-ion devices are reaching their maximum regarding energy density storage which restricts their appiicatíon in systems with large power needs, such as electric vehicles. Driven by this shortcoming, in the last few years, Lithium-Sulfur (Li-S) batteries are being considered as an alternative for the exploitatíon of energy storage and conversion systems with improved performance. Indeed, to the S cathodes is associated a theoretical specifíc capacity of 1672 mA h g-1 and a specifíc energy of 2600 W h kg-\ which are several times higher than the correspondent to other possible systems. The relative low atomic weight of S in comparison with other elements (e.g. cobalt) and the multí-electron transfer reactíons in the pair Li/S are at the source ofthis superior theoretícal performance of Li-S batteries.Este trabalho foi financiado por: projeto POCI-01-0145-FEDER-006984 - Laboratório Associado LSRE-LCM - financiado pelo Fundo Europeu de Desenvolvimento Regional (FEDER), através do COMPETE2020 – Programa Operacional Competitividade e Internacionalização (POCI)info:eu-repo/semantics/publishedVersio

Sulfadiazine-selective determination in aquaculture environment: Selective potentiometric transduction by neutral or charged ionophores

Solid-contact sensors for the selective screening of sulfadiazine (SDZ) in aquaculture waters are reported. Sensor surfaces were made from PVC membranes doped with tetraphenylporphyrin-manganese(III) chloride, α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin ionophores that were dispersed in plasticizer. Some membranes also presented a positive or a negatively charged additive. Phorphyrin-based sensors relied on a charged carrier mechanism. They exhibited a near-Nernstian response with slopes of 52 mV decade−1 and detection limits of 3.91 × 10−5 mol L−1. The addition of cationic lipophilic compounds to the membrane originated Nernstian behaviours, with slopes ranging 59.7–62.0 mV decade−1 and wider linear ranges. Cyclodextrin-based sensors acted as neutral carriers. In general, sensors with positively charged additives showed an improved potentiometric performance when compared to those without additive. Some SDZ selective membranes displayed higher slopes and extended linear concentration ranges with an increasing amount of additive (always <100% ionophore). The sensors were independent from the pH of test solutions within 2–7. The sensors displayed fast response, always <15 s. In general, a good discriminating ability was found in real sample environment. The sensors were successfully applied to the fast screening of SDZ in real waters samples from aquaculture fish farms. The method offered the advantages of simplicity, accuracy, and automation feasibility. The sensing membrane may contribute to the development of small devices allowing in locus measurements of sulfadiazine or parent-drugs

Optimization of Mediterranean Rainfed Pasture Systems in Portuguese Conditions, Based on a Linear Programing Model

info:eu-repo/semantics/publishedVersio