Avaliação dos impactos econômicos, sociais e ambientais de tecnologias geradas pela Embrapa Trigo - ano base 2007.

bitstream/CNPT-2010/40714/1/p-do96.pd

Heavy quasiparticles in the ferromagnetic superconductor ZrZn2

We report a study of the de Haas-van Alphen effect in the normal state of the ferromagnetic superconductor ZrZn2. Our results are generally consistent with an LMTO band structure calculation which predicts four exchange-split Fermi surface sheets. Quasiparticle effective masses are enhanced by a factor of about 4.9 implying a strong coupling to magnetic excitations or phonons. Our measurements provide insight in to the mechanism for superconductivity and unusual thermodynamic properties of ZrZn2.Comment: 5 pages, 2 figures (one color

Emissão de N2O por sistemas de manejo de solo em Passo Fundo, RS.

Orientador: Anderson Santi

Carbono acumulado por sistemas de manejo do solo em experimento de longa duração, em Passo Fundo, RS.

Orientador: Fabiano Daniel De Bona

Characterization of charge trapping mechanisms in GaN vertical Fin FETs under positive gate bias

In this paper, we present a comprehensive analysis of the charge trapping mechanisms that affect the GaN based vertical Fin FETs when the devices are submitted to positive gate bias. Devices with higher channel width show lower threshold voltage: with 2D simulations of the electron density we are able to explain the phenomenon and propose a trade-off to improve the technology. By using double pulse measurements and threshold voltage transients, two trapping/detrapping mechanisms under positive gate bias can be identified according to two voltage ranges. At low positive gate bias, electrons (previously trapped inside the oxide during the fabrication process) are detrapped towards the gate metal (mechanism 1). At higher gate bias, electrons are trapped at the GaN/oxide interface, moving the threshold towards positive values (mechanism 2). The second mechanism is observable at higher time of stress and it is predominant for higher voltages. Moreover, mechanism 2 is found to be recoverable only when the device is exposed to UV-light and electrons trapped in a specific level in the oxide acquire the energy necessary to escape and reach the n-type GaN and/or the UV-generated holes accumulate at the interface may reduce the trapped electron density. We demonstrate our hypothesis by calculating the interface state density in trapping/detrapping conditions by using photo-assisted Capacitance-Voltage measurements

Failure Physics and Reliability of GaN-Based HEMTs for Microwave and Millimeter-Wave Applications: A Review of Consolidated Data and Recent Results

Herein, the results are reviewed concerning reliability of high-electron mobility transistors (HEMTs) based on GaN, which currently represent the technology of choice for high-efficiency microwave and millimeter-wave power amplifiers. Several failure mechanisms of these devices are extensively studied, including converse piezoelectric effects, formation of conductive percolation paths at the edge of gate toward the drain, surface oxidation of GaN, time-dependent breakdown of GaN buffer, and of field-plate dielectric. For GaN HEMTs with scaled gate length, the simultaneous control of short-channel effects, deep-level dispersion, and hot-electron-induced degradation requires a careful optimization of epitaxial material quality and device design

The sieve-element endoplasmic reticulum: A focal point of phytoplasma-host plant interaction?

The rough endoplasmic reticulum (r-ER) is of paramount importance for adaptive responses to biotic stresses due to an increased demand for de novo synthesis of immunity-related proteins and signaling components. In nucleate cells, disturbance of r-ER integrity and functionality leads to the “unfolded protein response” (UPR), which is an important component of innate plant immune signalling. In contrast to an abundance of reports on r-ER responses to biotic challenges, sieve-element endoplasmic reticulum (SE-ER) responses to phytoplasma infection have not been investigated. We found that morphological SE-ER changes, associated with phytoplasma infection, are accompanied by differential expression of genes encoding proteins involved in shaping and anchoring the reticulum. Phytoplasma infection also triggers an increased release of bZIP signals from the (SE-ER)/r-ER and consequent differential expression of UPR-related genes. The modified expression patterns seem to reflect a trade-off between survival of host cells, needed for the phytoplasmic biotrophic lifestyle, and phytoplasmas. Specialized plasmodesmata between sieve element and companion cell may provide a corridor for transfer of phytoplasma effectors inducing UPR-related gene expression in companion cells

Clinical relevance of genetic variants of gonadotrophins and their receptors in controlled ovarian stimulation: a systematic review and meta-analysis

Genotype has been implicated in the outcome of ovarian stimulation. The analysis of patient-specific genotypes might lead to an individualized pharmacogenomic approach to controlled ovarian stimulation (COS). However, the validity of such an approach remains to be established

Improvement of imiquimod solubilization and skin retention via tpgs micelles: Exploiting the co-solubilizing effect of oleic acid

Imiquimod (IMQ) is an immunostimulant drug approved for the topical treatment of actinic keratosis, external genital-perianal warts as well as superficial basal cell carcinoma that is used off-label for the treatment of different forms of skin cancers, including some malignant melanocytic proliferations such as lentigo maligna, atypical nevi and other in situ melanoma-related diseases. Imiquimod skin delivery has proven to be a real challenge due to its very low water-solubility and reduced skin penetration capacity. The aim of the work was to improve the drug solubility and skin retention using micelles of d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), a water-soluble derivative of vitamin E, co-encapsulating various lipophilic compounds with the potential ability to improve imiquimod affinity for the micellar core, and thus its loading into the nanocarrier. The formulations were characterized in terms of particle size, zeta potential and stability over time and micelles performance on the skin was evaluated through the quantification of imiquimod retention in the skin layers and the visualization of a micelle-loaded fluorescent dye by two-photon microscopy. The results showed that imiquimod solubility strictly depends on the nature and concentration of the co-encapsulated compounds. The micellar formulation based on TPGS and oleic acid was identified as the most interesting in terms of both drug solubility (which was increased from few µg/mL to 1154.01 ± 112.78 µg/mL) and micellar stability (which was evaluated up to 6 months from micelles preparation). The delivery efficiency after the application of this formulation alone or incorporated in hydrogels showed to be 42-and 25-folds higher than the one of the commercial creams