Probing Ion-Ion and Electron-Ion Correlations in Liquid Metals within the Quantum Hypernetted Chain Approximation

We use the Quantum Hypernetted Chain Approximation (QHNC) to calculate the ion-ion and electron-ion correlations for liquid metallic Li, Be, Na, Mg, Al, K, Ca, and Ga. We discuss trends in electron-ion structure factors and radial distribution functions, and also calculate the free-atom and metallic-atom form-factors, focusing on how bonding effects affect the interpretation of X-ray scattering experiments, especially experimental measurements of the ion-ion structure factor in the liquid metallic phase.Comment: RevTeX, 19 pages, 7 figure

Molecular dynamics simulation study of the interdiffusion properties of liquid Na-K alloys

International audienc

Integral equation Study of the Square-Well Fluid for Varying Attraction Range

International audienc

Doses reduzidas de herbicidas de pós-emergência para controle de papua em soja Reduced rates of post-emergence herbicides for alexandergrass control in soybean

Em 1992/93 foram conduzidos dois experimentos a campo em Eldorado do Sul, RS, objetivando avaliar os herbicidas haloxyfop e sethoxydim no controle de papuã (Brachiaria plantaginea) em doses mais reduzidas que as usuais. Haloxyfop foi testado nas doses de 120, 90, 60, 30 e 30 + 30 g/ha. Sethoxydim foi avaliado nas doses de 184, 138, 92, 46 e 46 + 46 g/ha. Os herbicidas foram aspergidos 7 e 14 dias após semeadura da soja nos experimentos 1 e 2 quando as plantas de papuã encontravam-se com 1 a 2 folhas e com 3 a 4 folhas, respectivamente. As doses plenas foram aspergidas 2 semanas mais tarde que as doses reduzidas. Foi possível obter nível aceitável de controle de papuã em alguns tratamentos, em função do produto, da época e do método de aplicação. Aplicações seqüenciais de doses reduzidas de haloxyfop (30 + 30 g/ha) alcançaram controle de 72 e 95%, médias dos experimentos 1 e 2, respectivamente. No experimento 1, níveis de produtivídade de soja equivalentes ao do tratamento capinado só foram obtidos com doses plenas de haloxyfop e sethoxydim. No experimento 2, produtividades equivalentes à do capinado foram alcançadas nas doses plenas dos dois herbicidas e ainda com haloxyfop a 90 g/ha e a 30 + 30 g/ha. A pesquisa evidencia a necessidade do papuã ser totalmente eliminado para ser atingido rendimento máximo de soja.<br>Two trials were conducted under field conditions during the 1992/93 growing season in Eldorado do Sul, RS, Brazil, in order to evaluate haloxyfop and sethoxydim herbicides for Alexandergrass (Brachiaria plantaginea) control using rates lower than the usual. Haloxyfop rates tested were 120, 90, 60, 30, and 30 + 30 g/ha. Sethoxydim was evaluated under rates of 184, 138, 92, 46, and 46 + 46 g/ha. Herbicides were sprayed 7 and 14 days after soybean seeding date for experiments 1 and 2, when Alexandergrass plants presented 1 to 2 and 3 to 4 leaves, respectively. Herbicide full rates were applied 2 weeks after the reduced ones. It was possible to attain acceptable level of Alexandergrass control only with a few treatments, these being a function of the compound used, and also of time and method of application. Sequencial applications of reduced rates of haloxyfop (30 + 30 g/ha) achieved control levels of 72 and 95%, as averages for experiments 1 and 2, respectively. For experiment 1, soybean yield levels equivalent to hand hoeing were attained only by the full rates of haloxyfop and sethoxydim. In experiment 2, yields equivalent to the hoeing treatment were achíeved by full rates of both products and also by haloxyfop at 90 g/ha and sequencial applications of 30 + 30 g/ha. The research also attest the necessity of complete elimination of Alexandergrass infestation in order to get maximum soybean yield