Germinação in vitro de Hyptis leucocephala Mart. ex Benth. e Hyptis platanifolia Mart. ex Benth. / In vitro germination of Hyptis leucocephala Mart. ex Benth. and Hyptis platanifolia Mart. ex Benth

Hyptis leucocephala e Hyptis platanifolia (Lamiaceae) são espécies aromáticas endêmicas do semiárido nordestino e possuem grande importância econômica devido ao seu potencial medicinal. O presente trabalho teve por objetivo obter o protocolo para o estabelecimento inicial in vitro das espécies H. leucocephala e H. platanifolia. O meio de cultura WPM promoveu a maior porcentagem de germinação (96,81%) para H. leucocephala, porém não diferiu estatisticamente dos resultados obtidos no MS½ na última semana de cultivo. Para a germinação de sementes de H. platanifolia, o MS½ foi o meio que proporcionou a maior porcentagem (40,83%). O tipo de esterilização não interferiu na germinação in vitro para as duas espécies. Para a espécie H. platanifolia, quando se utilizou o fechamento dos tubos de ensaio com tampão de algodão, a hiperidricidade foi eliminada; porém, a porcentagem de germinação das sementes foi menor. Avaliando-se o tipo de meio de cultura no crescimento in vitro de H. leucocephala observou-se que este fator não influenciou no número de brotações, nem o comprimento de parte aérea e da matéria seca de raiz. O meio MS proporcionou incremento para o número de folhas, matéria seca da parte aérea, e comprimento da maior raiz, enquanto o meio MS½ foi o que promoveu maior número de raízes. O meio de cultura ideal para a germinação de H. leucocephala e H. platanifolia foi o MS½, podendo ser esterilizado com hipoclorito de sódio, enquanto que o MS foi o melhor meio de cultura para o crescimento in vitro de H. leucocephala.

The Hyptis leucocephala and Hyptis platanifolia (Lamiaceae) are aromatic species, endemic to the Brazilian Semiarid northeast, and they have great economic importance becaude of their pharmacological potential. This study aimed to obtain the protocol for the in vitro establishment of H. leucocephala and H. platanifolia plants. The WPM promoted higher germination percentage (96.81%) for H. leucocephala, but there was no difference between the results obtained in ½MS, in the last week of cultivation. For the germination of H. platanifolia, ½MS was the one that provided the highest percentage (40.83%). The type of sterilization did not affect the in vitro germination of both species. For the H. platanifolia species, when we closed the tubes with a cotton plug, hyperhydricity was eliminated, but the percentage of seed germination was the lowest one. Evaluating the type of culture medium on the in vitro growth of H. leucocephala, it did not influence the number of shoots, length of shoot or root dry matter. The MS medium promoted an increase of the number of leaves, dry shoot and longest root length, and the ½MS medium was more suitable for root induction. The optimal culture medium for the germination of H. leucocephala and H. platanifolia is ½MS, as it can be sterilized with sodium hypochlorite, while the MS was the best culture medium for the in vitro growth of H. leucocephala.

Electronic structure of the band-filling-controlled CaVO3 and LaVO3 compounds.

We studied the electronic structure of the band-filling CaVO(3) and LaVO(3) compounds. The experimental techniques were photoemission (PES) and x-ray absorption (XAS) spectroscopy. The experimental results were analyzed using an extended cluster model. The ground states of CaVO(3) and LaVO(3) are highly covalent and contain a considerable 3d(n + 1)L contribution. The CaVO(3) compound is in the charge transfer regime (Δ < U), whereas the LaVO(3) material is in the intermediate regime (Δ âˆ¼ U). The spectral weight distributions reveal that CaVO(3) is a coherent metal and that LaVO(3) is a p-d insulator. The photoemission of CaVO(3) shows the coherent peak (3d(1)C) and the incoherent feature (3d(1)L). The spectrum of insulating LaVO(3) presents only the incoherent structure (3d(2)L), whereas the coherent peak is replaced by the Mott-Hubbard screening (3d(2)D). This transfer of spectral weight is responsible for the opening of the experimental bandgap. The incoherent feature contains a considerable O 2p character and cannot be attributed to the lower Hubbard band. Further, the relative V 3d-O 2p cross section helps to explain the photon energy dependence of the PES spectra. The addition spectra of both CaVO(3) and LaVO(3) are dominated by the 3d(n + 1) final state configuration. The distribution of spectral weight is mainly dictated by intra-atomic exchange and crystal field splittings. The coherent contribution is less important than in photoemission, and is greatly diminished in the O 1s x-ray absorption spectra.

A synchrotron beamline for delivering high purity vacuum ultraviolet photons.

We report on the current status and performance of the toroidal grating monochromator beamline at the Brazilian Synchrotron Light Laboratory (Laboratorio Nacional de Luz Sincrotron). This beamline provides photons in the vacuum ultraviolet and soft x-ray regions from 12 to 330 eV with three interchangeable gratings. We report on the improvement, which allows the possibility of choosing the light polarization degree from linear to almost circular. Here, we also describe the development of a new apparatus, namely, the mirror-inserted harmonic attenuator and calibrating-device with a long length (MIRHACLLE). All beamlines based on diffraction gratings suffer from the problem of high harmonics contaminations to some extent. The MIRHACLLE provides a way to efficiently suppress high harmonics from 25% to 1 ppm in a grazing incidence bending magnet beamline. Its principle of operation relays on the absorption of the high energy photons in a gas phase region. It allows negligible high harmonics contamination for photon energies ranging from 12 eV to the gas first ionization threshold, 21.6 eV, in the case of neon. We also demonstrate the possibility to use this device for energy calibration and resolution evaluation together with any experiment needing its filtering capabilities. The device is also very cost effective compared to other filters presented previously in the literature.

Relativistic and interchannel coupling effects in photoionization angular distributions by synchrotron spectrocopy of laser cooled atoms.

We investigate the angular distribution of photoionization fragments at low photon energies (12-40 eV) in an open shell atom, by synchrotron radiation recoil ion momentum spectroscopy in a laser cooled and trapped sample. For cesium atoms, for which relativistic effects play an important role and the ion recoil is relatively small, we could determine large and rapid changes of the asymmetry parameter beta from two, observed for s electrons outside resonances and far from the Cooper minimum. They can be explained by relativistic effects and interchannel coupling arising from final state configuration mixing.