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The information about where crops are distributed is useful for agri-environmental assessments, but is chiefly important for food security and agricultural policy managers. The quickness with which this information becomes available, especially over large areas, is important for decision makers. Methodologies have been proposed for the study of crops. Most of them require field survey for ground truth data and a single crop map is generated for the whole season at the end of the crop cycle and for the next crop cycle a new field survey is necessary. Here, we present models for recognizing maize (Zea mays L.), beans (Phaseolus vulgaris L.), and alfalfa (Medicago sativa L.) before the crop cycle ends without current-year field survey for ground truth data. The models were trained with an exhaustive field survey at plot level in a previous crop cycle. The field surveys begin since days before the emergence of crops to maturity. The algorithms used for classification were support vector machine (SVM) and bagged tree (BT), and the spectral information captured in the visible, red-edge, near infrared, and shortwave infrared regions bands of Sentinel 2 images was used. The models were validated within the next crop cycle each fifteen days before the mid-season. The overall accuracies range from 71.9% (38 days after the begin of cycle) to 87.5% (81 days after the begin cycle) and a kappa coefficient ranging from 0.53 at the beginning to 0.74 at mid-season.

Assuntos

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Micro/nanomachines (MNMs) correspond to human-made devices with motion in aqueous solutions. There are different routes for powering these devices. Light-driven MNMs are gaining increasing attention as fuel-free devices. On the other hand, Plasmonic nanoparticles (NPs) and their photocatalytic activity have shown great potential for photochemistry reactions. Here we review several photocatalyst nanosystems, with a special emphasis in Plasmon induced photocatalytic reactions, as a novel proposal to be explored by the MNMs community in order to extend the light-driven motion of MNMs harnessing the visible and near-infrared (NIR) light spectrum.

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Plasmonic reversible gas sensors are of paramount importance for the monitoring of indoor environments. Herein, we design and engineer a plasmonic foam, with a high surface area, confined inside a capillary glass tube for the live monitoring of carbon monoxide (CO) in closed environments using surface-enhanced resonance Raman scattering. The illumination of the sensor with light during the flow of air allows the live monitoring of the concentration of atmospheric CO through surface-enhanced resonance Raman scattering. The sensor was prepared with a detection range from 10 to 40 ppm, due to health needs. The results show a sensitive, selective, reversible and robust sensor applicable to the monitoring of CO levels but also to other gas species upon appropriate functionalization.

RESUMO

Herein, a series of N-doped carbon nanotube (CNx) samples were obtained by modifying the synthesis temperature. Consequently, the proportion of graphitic nitrogen (Ngraph) in the samples was systematically increased as a function of temperature. This allowed evaluation of the role of the CNx graphitic nitrogen in the oxygen reduction reaction (ORR). A correlation between the Ngraph content and the ORR onset potential was observed, which shifted to more positive potentials with an increase in kinetic current density (jk); this showed that Ngraph played a significant catalytic role in the ORR. The samples with high Ngraph content favored the two-electron pathway for the ORR not only in basic media (pH = 13) but also in neutral media (pH = 7), representing an attractive alternative for wastewater remediation through the on-site generation of H2O2. The energetic calculations showed that the formation of H2O2 must be favorable in the presence of graphitic nitrogen sites. Finally, the performance of the buckypaper arrangement was evaluated, and the CNx buckypaper showed a higher cathodic current peak as compared to CNx traditional ink dispersions. Overall, this study not only sheds light on the role of Ngraph in the ORR, but also demonstrates that CNx buckypaper is an efficient 3D electrode for electrocatalytic applications.

RESUMO

Low concentrations of hazardous gases are difficult to detect with common gas sensors. Using semiconductor nanostructures as a sensor element is an alternative. Single ZnO nanowire gas sensor devices were fabricated by manipulation and connection of a single nanowire into a four-electrode aluminum probe in situ in a dual-beam scanning electron microscope-focused ion beam with a manipulator and a gas injection system in/column. The electrical response of the manufactured devices shows response times up to 29 s for a 121 ppm of H2 pulse, with a variation in the nanowire resistance appreciable at room temperature and at 373.15 K of approximately 8% and 14% respectively, showing that ZnO nanowires are good candidates to detect low concentrations of H2.

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Electrical current could be efficiently guided in 2D nanotube networks by introducing specific topological defects within the periodic framework. Using semiempirical transport calculations coupled with Landauer-Buttiker formalism of quantum transport in multiterminal nanoscale systems, we provide a detailed analysis of the processes governing the atomic-scale design of nanotube circuits. We found that when defects are introduced as patches in specific sites, they act as bouncing centers that reinject electrons along specific paths, via a wave reflection process. This type of defects can be incorporated while preserving the 3-fold connectivity of each carbon atom embedded within the graphitic lattice. Our findings open up a new way to explore bottom-up design, at the nanometer scale, of complex nanotube circuits which could be extended to 3D nanosystems and applied in the fabrication of nanoelectronic devices.

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Sirolimus (SRL) is a new immunosuppressive drug approved for renal transplantation, but is being used increasingly in orthotopic liver transplantation (OLT). Compared with the calcineurin inhibitors, SRL has different mechanisms of action and side effects profile. Thus, this drug offers significant potential advantages over other immunosuppressive agents. SRL does not cause glucose intolerance, hypertension or renal failure, but it may cause dyslipidemia, hepatic artery thrombosis, thrombocytopenia, anemia, leukopenia, oral mucosa ulcers, edema, arthralgias and wound complications. SRL inhibits the signal of interleukin 2 at a post-receptor level, inhibiting lymphocyte proliferation and fibroblast proliferation. It also has antineoplastic and antifungal effects. We report a 10 years old girl who underwent OLT, experiencing a biopsy-proven recurrent acute rejection (AR) in spite of using three immunosuppressive agents (tacrolimus, mofetil micofenolate and steroids). She developed diabetes mellitus as a consequence of the immunosuppressive therapy. She was rescued with SRL, not experiencing AR again. Mofetil micofenolate, steroids and insulin could be discontinued and tacrolimus doses were reduced, without experiencing severe complications. SRL is a new and safe immunosuppressive agent for rescue in patients with OLT and recurrent AR.

Assuntos

RESUMO

Sirolimus (SRL) is a new immunosuppressive drug approved for renal transplantation, but is being used increasingly in orthotopic liver transplantation (OLT). Compared with the calcineurin inhibitors, SRL has different mechanisms of action and side effects profile. Thus, this drug offers significant potential advantages over other immunosuppressive agents. SRL does not cause glucose intolerance, hypertension or renal failure, but it may cause dyslipidemia, hepatic artery thrombosis, thrombocytopenia, anemia, leukopenia, oral mucosa ulcers, edema, arthralgias and wound complications. SRL inhibits the signal of interleukin 2 at a post-receptor level, inhibiting lymphocyte proliferation and fibroblast proliferation. It also has antineoplastic and antifungal effects. We report a 10 years old girl who underwent OLT, experiencing a biopsy-proven recurrent acute rejection (AR) in spite of using three immunosuppressive agents (tacrolimus, mofetil micofenolate and steroids). She developed diabetes mellitus as a consequence of the immunosuppressive therapy. She was rescued with SRL, not experiencing AR again. Mofetil micofenolate, steroids and insulin could be discontinued and tacrolimus doses were reduced, without experiencing severe complications. SRL is a new and safe immunosuppressive agent for rescue in patients with OLT and recurrent AR.

Assuntos