10 research outputs found
Mineral nutrition of vegetable crops: XXV - Mineral nutrition of new zealand spinach plant (Tetragonia expansa Murr.)
The present work was carried out in order to study: a - the effect of omission and presence of the macronutrients and boron on the growth of the plants; b - deficiency symptoms of macronutrients, as well of boron; c - the effect of the deficiency of each nutrient on the chemical composition of the plants. Young spinach plants were grown in pots containing pure quartz sand. Several times a day the plants were irrigated by percolation with nutrient solutions. The treatments were: complete solution and deficient solution, in which each one of the macronutrients was omitted as well boron. Soon as the malnutrition symptoms appered, the plants were harvested and analysed chemically. - symptoms of malnutrition are easily observed for N, K, Ca and B. - symptoms of malnutrition for P, S and Mg are not easily identified. - the nutrient content, in dry matter, in deficient leaves and healthy leaves is:O trabalho teve como objetivo estudar alguns aspectos da nutrição mineral do espinafre (Tetragonia expansa Murr.) no que concerne: 1 - Efeitos da omissĂŁo dos macronutrientes e do boro, na obtenção de um quadro sintomatolĂłgico; 2 - Efeitos das carĂȘncias na produção de matĂ©ria seca e composição quĂmica da planta. Mudas com trinta dias de idade foram transplantadas para soluçÔes nutritivas carentes nos macronutrientes e/ou em boro. A coleta das plantas foi realizada quando os sintomas de deficiĂȘncia se tornaram evidentes. No material seco procedeu-se a anĂĄlise quĂmica. Os dados mostram que: 1 - os sintomas visuais de deficiĂȘncia de N, K, Ca e B apresentam-se bem definidos; sendo que os de P, Mg e S sĂŁo de difĂcil caracterização ; 2 - os teores dos nutrientes em plantas sadias e deficientes sĂŁo
He-3 polarization via optical pumping in a birefringent cell
A sapphire cell was used to obtain a high He-3 nuclear polarization by means of spin-exchange optical pumping. The phase-shift difference between ordinary and extraordinary rays is well controlled using the thickness of the birefringent sapphire window so that a high circular polarization is obtained in the cell. Neutron transmission through the polarized He-3 gas was measured as a function of neutron energy. A large He-3 polarization of 63 +/- 1% was obtained at a He-3 pressure of 3.1 atm. Neutron polarizations of 97 and 90 % were obtained with transmission rates of 15 and 22 % at 10 and 20 meV, respectively. (c) 2005 American Institute of Physics
TANGRA â an experimental setup for basic and applied nuclear research by means of 14.1 MeV neutrons
For investigation of the basic characteristics of 14.1 MeV neutron induced nuclear reactions on a number of important isotopes for nuclear science and engineering, a new experimental setup TANGRA has been constructed at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research in Dubna. For testing its performance, the angular distribution of gamma-rays (and neutrons) from the inelastic scattering of 14.1 MeV neutrons on high-purity carbon was measured and the angular anisotropy of gamma-rays from the reaction 12C(n, n'g)12C was determined. This reaction is important from fundamental (differential cross-sections) and practical (non-destructive elemental analysis of materials containing carbon) point of view. The preliminary results for the anisotropy of the gamma-ray emission from the inelastic scattering of 14.1-MeV neutrons on carbon are compared with already published literature data. A detailed data analysis for determining the correlations between inelastic scattered neutron and gamma-ray emission will be published elsewhere.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard
Determination of T-noninvariant amplitude for polarized-neutron interaction with polarized nuclei by the oscillating-field method
TANGRA-Setup for the Investigation of Nuclear Fission induced by 14.1 MeV neutrons
The new experimental setup TANGRA (Tagged Neutrons & Gamma Rays), for the investigation of neutron induced nuclear reactions, e.g. (n,xnâ), (n,xnâÎł), (n,Îł), (n,f), on a number of important isotopes for nuclear science and engineering (235,238U, 237Np, 239Pu, 244,245,248Cm) is under construction and being tested at the Frank Laboratory of Neutron Physics (FLNP) of the Joint Institute for Nuclear Research (JINR) in Dubna.
The TANGRA setup consists of: a portable neutron generator ING-27, with a 64-pixel Si charge-particle detector incorporated into its vacuum chamber for registering of α-particles formed in the T(d, n)4He reaction, as a source of 14.1 MeV steady-state neutrons radiation with an intensity of âŒ5x107n/s; a combined iron (Fe), borated polyethylene (BPE) and lead (Pb) compact shielding-collimator; a reconfigurable multi-detector (neutron plus gamma ray detecting system); a fast computer with 2 (x16 channels) PCI-E 100 MHz ADC cards for data acquisition and hard disk storage; Linux ROOT data acquisition, visualization and analysis software. The signals from the α-particle detector are used to âtagâ the neutrons with the coincident α-particles. Counting the coincidences between the α-particle and the reaction-product detectors in a 20ns time-interval improves the effect/background-ratio by a factor of âŒ200 as well as the accuracy in the neutron flux determination, which decreases noticeably the overall experimental data uncertainty.JRC.G.2-Standards for Nuclear Safety, Security and Safeguar