We employed the Schwinger multichannel method to compute elastic cross sections for low-energy electron collisions with ethane (C2H6). The calculations were carried out in the static-exchange and static-exchange plus polarization approximations for energies up to 12 eV. Our integral cross section shows good agreement with experimental data and with theoretical results for energies above 5 eV. There are some differences for energies below 5 eV between our results and the available experimental and theoretical results. Our differential cross sections also agree well with the experiment and with theory for energies above 5 eV; below this energy our results agree in shape, but are smaller than the available experimental and theoretical results. We discuss possible reasons for these discrepancies. We found a broad structure in the integral cross section around 8.5 eV and also a Ramsauer-Townsend minimum around 0.2 eV. These results are in agreement with the experimental observations and theoretical results.

A padronização de um fitoterápico é etapa imprescindível para garantia da qualidade de medicamentos contendo plantas medicinais. Objetivou-se padronizar Syzygiam cumini (L.) Skeels e para tanto se estabeleceram parametros tais como, avaliação morfoanatômica das folhas, morfológica das flores e dos frutos, avaliação granulométrica da droga rasurada (frutos), determinação da umidade, avaliação dos processos de secagem, determinação do teor de extrativos e do teor de taninos (monômeros e polimeros). O estudo anatômico das folhas revelou a inexistência de pêlos no sistema dérmico, assim como a ocorrência de glândulas secretoras, drusas, colênquima e esclerênquima. As flores são hermafroditas, com androceu polistêmone e gineceu com ovário ínfero, gamocarpelar, bilocular com placentação axial. Observou-se elevado teor extrativo (38,57%). O diâmetro médio de partícula dos frutos secos moídos ficou em 0,630 mm. O processo de secagem dos frutos influenciou o teor de taninos totais. O teor de taninos determinado ficou em 5,10% para monômeros e 11,30% para os polimeros.

The phytotherapics standardization is an important step for the warranty of the quality of the drugs contends medicinal plants. The aim of this paper was to standardize and establish parameters seeking the characterization of the drug, according to technical pharmacopoeias and in some cases, other techniques were developed. Morphologic description of leaves, flowers and fruits, granulometric analysis of the ground drugs, dry residues, evaluations in the drying methods, determination of the extractive drift and tannins values (monomers and polymers) were executed, being the monomers in the range of 5,10% and 11,30% for the polymeric ones.

We present the results of applications of the iterative Schwinger variational method to obtain photoionization cross sections and phoelectron angular distributions for ionization out of the four outermost valence orbitals 1b3u, 1b3g, 3ag and 1b2u of ethylene for photon energies ranging from near threshold to 30 eV. The observed resonance-like maxima in the cross sections for ionization of the 1b3g and 3ag orbitals are reproduced in our calculations. The disagreement between our cross sections and the experimental data for the 1b3u orbital below 17 e V is attributed to autoionization, which is not accounted for in our calculations.