Características produtivas e nutricionais do feno de trigo cultivado em dois níveis de adubação nitrogenada e estádios de colheita / Productive and nutritional characteristics of wheat hay cultivated in two nitrogen fertilization levels and harvest stages

O objetivo do presente trabalho foi avaliar a produção de fitomassa fresca e de fitomassa seca, assim como a composição física e bromatológica do feno do trigo cultivar BRS Umbu sob efeitos de dois níveis de adubação nitrogenada (120kg ha-1 e 180kg ha-1) e dois estádios fenológicos de colheita (pré-florescimento e grão farináceo). O delineamento experimental foi blocos ao acaso, em esquema fatorial 2x2, composto por quatro tratamentos com quatro repetições. Não houve interação (P>0,05) entre os níveis de adubação nitrogenada e os estádios fenológicos de colheita para todas as variáveis. A produção de fitomassa seca (P<0,05) nos estádios de grão farináceo e pré-florescimento foi de 10.171 e 4.982kg ha-1, respectivamente. A maior dose de N incrementou a produção de fitomassa seca em 775kg ha-1. Houve aumento da participação de espigas com o avanço do ciclo, apresentando-se 43,0% e 16,2% nos estádios grão farináceo e pré-florescimento, respectivamente. No estádio fenológico de pré-florescimento, a participação de folha verde foi superior (37,1% contra 9,8% da MS total). O feno colhido em estádio de grão farináceo apresentou menores teores de proteína bruta e fibra em detergente neutro. Os fenos produzidos apresentaram características distintas, o que permite seu uso em diferentes estratégias de alimentação de ruminantes.(AU)

The objective was to evaluate the production of the fresh and dry weight, physical and chemical composition of wheat hay, cv. BRS UMBU, under effects of two levels of nitrogen fertilization (120kg ha-1 and 180kg ha-1) and two harvest stages (pre-flowering and grain dough). The experimental design was randomized blocks in factorial 2X2, composed of four treatments with four replications. There was no interaction (p>0.05) between the levels of nitrogen fertilization and growth stages of harvest for all variables. The production of dry matter in the dough stage and pre-flowering were 10.171 and 4.982kg ha-1, respectively. The higher N rates increased the production of dry matter of 775kg ha-1. There was increased participation of spikes with the advancement of the cycle, presenting 43.0% and 16.2% in the dough stage and pre-flowering, respectively. In the growth stage of pre-flowering, the share of green leaf was higher (37.1% against 9.8% of the total MS). The hay harvested at dough stage had lower NDF and CP levels. Thus, each treatment presented favorable characteristics allowing its use in different strategies in ruminant nutrition.(AU)

The electron energy dependence of the TL response for CVD diamonds.

The thermoluminescent (TL) response of CVD diamond is investigated after bombarding a sample with monoenergetic electrons (at 6 and 21 MeV). Irradiations are performed at room temperature with a medical linear electron accelerator PRIMUS (KD2-Siemens). The TL curve shows a peak at approximately 540 K. The area of this peak as a function of fluence exhibits saturation behaviour at high energies. Moreover, there is no significant difference between the TL response at 21 MeV electrons and that at 6 MeV. In order to explain these experimental results, calculations of the ionising dose have been performed with the code MCNPX (Monte Carlo N-Particle) for various incident energies from 0.1 MeV up to 100 MeV.

Influence of absorbed dose and deep traps on thermoluminescence response: a numerical simulation.

Numerical simulations based on standard rate equations are carried out to study the dependence of the thermoluminescence (TL) response on the absorbed dose. The model, which includes thermally stimulated exoelectronic emission (TSEE), uses three electron traps--two active and one thermally disconnected (TD)--and one deep hole trap acting as a recombination centre. After instantaneous creation of a given dose of electron-hole pairs, one first follows isothermal recombination and trap filling before simulating the TL readout. Influence of TD traps and specific effects due to trap saturation are illustrated. A systematic study of the TL response is performed in wide ranges of the determining parameters. The dose dependence is found to be quadratic, linear or intermediate according to their relative values. Results are explained in terms of recombination-trapping competition, trap occupancy and in relation with the presence of TSEE.

Kerma rate effects on thermoluminescent response of CVD diamond.

The thermoluminescence (TL) response of chemical vapour deposition diamond is studied after X-irradiation (45 kV) at room temperature for various air kerma rates ranging from 0.7 to 100 Gy.min(-1). For a given air kerma, the TL signal as a function of air kerma rate exhibits large variations and is higher for low air kerma rates than for higher ones. In order to explain these results, the simplest energy-level scheme has been considered, that is, with only one electron trap and one recombination centre. Kinetic equations are numerically solved. Calculations are made for various electron-hole generation rates and show that the trap filling as a function of electron-hole generation rate follows, actually, the same evolution as the one of experimental TL response. The kerma rate effect on TL response is explained by the competitivity between the recombination and the trapping processes during irradiation.

Thermoluminescence properties of CVD diamond for clinical dosimetry use.

The application of diamond to dosimetry is desirable because of its tissue equivalence, chemical inertness and small size, but this has not been commercially viable owing to the non-reproducible response of natural diamond. The chemical vapour deposition (CVD) of diamond permits controlled, reproducible and large-scale production of this material at potentially low cost. An investigation of some clinically relevant features like the depth-dose distribution as well as the absorbed dose profile, obtained using thermoluminescence (TL), is reported for several CVD diamond films. The TL characterisation presented here shows that CVD diamond films should be excellent TL-mode detectors in instances of radiotherapy and in vivo radiation dosimetry.

Neutron absorbed dose determination by calculations of recoil energy.

The aim of this work is to calculate the absorbed dose to matter due to neutrons in the 5-150 MeV energy range. Materials involved in the calculations are Al2O3, CaSO4 and CaS, which may be used as dosemeters and have already been studied for their luminescent properties. The absorbed dose is assumed to be mainly due to the energy deposited by the recoils. Elastic reactions are treated with the ECIS code while for the non-elastic ones, a Monte Carlo code has been developed and allowed to follow the nucleus decay and to determine its characteristics (nature and energy). Finally, the calculations show that the absorbed dose is mainly due to non-elastic process and that above 20 MeV this dose decreases slightly with the neutron energy.