1,366 research outputs found
Lichen xanthones as models for new antifungal agents
Due to the emergence of multidrug-resistant pathogenic microorganisms, the search for new antimicrobial compounds plays an important role in current medicinal chemistry research. Inspired by lichen antimicrobial xanthones, a series of novel chlorinated xanthones was prepared using five chlorination methods (Methods A–E) to obtain different patterns of substitution in the xanthone scaffold. All the synthesized compounds were evaluated for their antimicrobial activity. Among them, 3-chloro-4,6-dimethoxy-1-methyl-9H-xanthen-9-one 15 showed promising antibacterial activity against E. faecalis (ATCC 29212 and 29213) and S. aureus ATCC 29213. 2,7-Dichloro-3,4,6-trimethoxy-1-methyl-9H-xanthen-9-one 18 revealed a potent fungistatic and fungicidal activity against dermatophytes clinical strains (T. rubrum, M. canis, and E. floccosum (MIC = 4–8 µg/mL)). Moreover, when evaluated for its synergistic effect for T. rubrum, compound 18 exhibited synergy with fluconazole (ΣFIC = 0.289). These results disclosed new hit xanthones for both antibacterial and antifungal activity.This work was partially supported through national funds provided by FCT/MCTES - Foundation for Science and Technology from the Ministry of Science, Technology, and Higher Education (PIDDAC) and the European Regional Development Fund (ERDF) through the COMPETE - Programa Operacional Factores de Competitividade (POFC) programme, under the Strategic Funding UID/Multi/04423/2013, the projects POCI-01-0145-FEDER-028736 and POCI-01-0145-FEDER-016790 (PTDC/MAR-BIO/4694/2014; 3599-PPCDT) in the framework of the programme PT2020, as well as by the project INNOVMAR - Innovation and Sustainability in the Management and Exploitation of Marine Resources (reference NORTE-01-0145-FEDER-000035, within Research Line NOVELMAR), supported by North Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). Diana I. S. P. Resende also acknowledge for her grant (NOVELMAR/BPD_2/2016-019) and Patrícia Pereira-Terra for her grant (NOVELMAR/BPD/2017/012)
Potential for macro and micronutrients extraction from tomato plants with different soil water stresses
Different tomato cultivars may present differentiated water needs, making it
indispensable to study water demand. Thus, the objective of this work was to evaluate the
influence of six water stresses in the soil on the extraction potential of macro and micronutrients
in the aerial part of tomato in vegetative stage, cultivar ‘Dominador’ F1, under protected
cultivation and drip. The experiment was installed in a greenhouse with a randomized block
design with four replications. The treatments consisted of six soil water stresses as indicative of
the time of irrigation. The preset stresses were 20, 45, 70, 95, 120 and 145 kPa at 20 cm depth.
At 140 days after transplanting, the variables evaluated were: the macro and micronutrient content
of shoots. The results showed that to obtain higher levels of macro (P and S) and micronutrients
(B and Cu) of the total aerial part of the ‘Dominador’ tomato plant F1, it was obtained at a voltage
of 20 kPa, and its value was reduced linearly with the increase of the water tension in the soil
Models of electron transport in single layer graphene
The main features of the conductivity of doped single layer graphene are
analyzed, and models for different scattering mechanisms are presented.Comment: 15 pages. Submitted to the Proceedings of the ULTI symposium on
Quantum Phenomena and Devices at Low Temperatures, Espoo, Finland, to be
published in the Journ. of Low. Temp. Phy
Efecto del paisaje y del manejo del olivar sobre la polilla del olivo Prays oleae (Bernard)
El manejo del paisaje y los cultivos puede constituir una herramienta importante para la
implementación de estrategias de control biológico por conservación, como consecuencia de la
contribución que el uso de diseños paisajísticos adecuados y la aplicación de determinados
manejos pueden representar en el incremento de las necesidades y la acción de los enemigos
naturales. En el presente trabajo fue realizado un estudio multi-escala sobre el efecto de la
estructura del paisaje y el manejo del cultivo en la polilla del olivo, Prays oleae. Para ello, se
analizó: (i) la respuesta de la plaga a la estructura del paisaje a diferentes escalas usando como
variables explicativas diferentes índices de composición y configuración del paisaje previamente
seleccionados; (ii) la respuesta de la plaga al manejo de olivar (integrado y orgánico). El análisis
fue realizado mediante modelos aditivos generalizados mixtos. Los resultados indicaron que
varios índices de composición del paisaje (índices de biodiversidad, presencia de matorrales y de
otros cultivos) influenciaron negativamente la abundancia de la polilla del olivo siendo el efecto
menor a escalas mayores. Sin embargo, el efecto de los índices de configuración no fue
concluyente. La latitud y probablemente las diferencias climáticas se mostraron determinantes en
la abundancia de la polilla del olivo. El manejo del cultivo sin embargo no afectó a la plaga. Por
tanto, los diseños de la composición del paisaje a pequeña escala parecen ser cruciales para el
control de la polilla del olivo. Cabe destacar que la configuración y el manejo a escalas mayores
podrían ser importantes para otras plagas y enemigos naturales, debiendo tenerse en
consideración en el diseño de estrategias para control biológico por conservación en olivar.info:eu-repo/semantics/publishedVersio
Effects of pneumonectomy on nitric oxide synthase expression and perivascular edema in the remaining lung of rats
Pneumonectomy is associated with high mortality and high rates of complications. Postpneumonectomy pulmonary edema is one of the leading causes of mortality. Little is known about its etiologic factors and its association with the inflammatory process. The purpose of the present study was to evaluate the role of pneumonectomy as a cause of pulmonary edema and its association with gas exchange, inflammation, nitric oxide synthase (NOS) expression and vasoconstriction. Forty-two non-specific pathogen-free Wistar rats were included in the study. Eleven animals died during or after the procedure, 21 were submitted to left pneumonectomy and 10 to sham operation. These animals were sacrificed after 48 or 72 h. Perivascular pulmonary edema was more intense in pneumonectomized rats at 72 h (P = 0.0131). Neutrophil density was lower after pneumonectomy in both groups (P = 0.0168). There was higher immunohistochemical expression of eNOS in the pneumonectomy group (P = 0.0208), but no statistically significant difference in the expression of iNOS. The lumen-wall ratio and pO2/FiO2 ratio did not differ between the operated and sham groups after pneumonectomy. Left pneumonectomy caused perivascular pulmonary edema with no elevation of immunohistochemical expression of iNOS or neutrophil density, suggesting the absence of correlation with the inflammatory process or oxidative stress. The increased expression of eNOS may suggest an intrinsic production of NO without signs of vascular reactivity.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)CNP
Atividade antimicrobiana de extratos hidroalcólicos de espécies da coleção de plantas medicinais CPQBA/UNICAMP
Extratos obtidos a partir de 45 espécies da Coleção de Germoplasmas do CPQBA foram estudados quanto à atividade antimicrobiana. As espécies que apresentaram forte inibição (Concentração Mínima Inibitória até 0,5 mg/mL) para os respectivos microrganismos foram: Achillea millefolium (0,5), Mikania laevigata (0,04), Solidago chilensis (0,1), Piper marginatum (0,2) para Staphylococcus aureus; Aloysia gratissima (0,1), P. marginatum (0,2), M. laevigata (0,09) para Bacillus subtilis e Mentha pullegium (0,3), Mikania glomerata (0,1), M. laevigata (0,04), Stachytarpeta cayenensis (0,2) e Bacharis dracunculifolia (0,5) para Streptococcus faecium. De acordo com os resultados, ressaltamos a espécie M. laevigata por apresentar inibição contra três das bactérias estudadas, em concentrações similares a do cloranfenicol, padrão de referência utilizado
Multi-walled carbon nanotubes as a platform for Immunoglobulin G attachment
Nanomaterials have been extensively used in different applications due to their peculiar characteristics and
nanoscale dimensions. Among nanoparticles, carbon-based nanomaterials are becoming highly attractive for
biomedical applications such as diagnosis, tissue engineering, drug delivery, and biosensing. The conjugation of
carbon-based nanomaterials with antibodies combines the properties of these materials with the specific and
selective recognition ability of the antibodies to antigens. The present work proposes a process intensification
approach for immunoglobulin G (IgG present in rabbit serum) attachment on multi-walled carbon nanotubes
(MWCNTs) in a single step. The effect of several parameters, namely MWCNTs external diameter, rabbit serum
concentration, MWCNTs functionalization and pH value, on the IgG attachment yield was evaluated. The dilution
of rabbit serum decreased other protein attachment, namely rabbit serum albumin (RSA), while increasing the
IgG yield to 100%. The interaction mechanisms between IgG and MWCNTs were evaluated at pH 5.0 to 8.0. The
protonation of IgG amino acids indicates that N-term are the most reactive amino acids in the antibody structure.
The identification of the N-term reactivity at pH 8.0 allows to indicate a possible orientation of the antibody over
the MWCNTs surface, described as “end-on”. Since the amount of RSA attached to MWNT decreased with the
increase in serum dilution, the IgG orientation and amine activity was not affected. This orientation demonstrates
that the IgG attachment over the surface of the MWCNTs could be an effective strategy to maintain the antigen
recognition by the antibody, and to be used for biomedical applications.publishe
Exact eigenstate analysis of finite-frequency conductivity in graphene
We employ the exact eigenstate basis formalism to study electrical
conductivity in graphene, in the presence of short-range diagonal disorder and
inter-valley scattering. We find that for disorder strength, 5, the
density of states is flat. We, then, make connection, using the MRG approach,
with the work of Abrahams \textit{et al.} and find a very good agreement for
disorder strength, = 5. For low disorder strength, = 2, we plot the
energy-resolved current matrix elements squared for different locations of the
Fermi energy from the band centre. We find that the states close to the band
centre are more extended and falls of nearly as as we move away
from the band centre. Further studies of current matrix elements versus
disorder strength suggests a cross-over from weakly localized to a very weakly
localized system. We calculate conductivity using Kubo Greenwood formula and
show that, for low disorder strength, conductivity is in a good qualitative
agreement with the experiments, even for the on-site disorder. The intensity
plots of the eigenstates also reveal clear signatures of puddle formation for
very small carrier concentration. We also make comparison with square lattice
and find that graphene is more easily localized when subject to disorder.Comment: 11 pages,15 figure
Modelling the particle contact influence on the Joule heating and temperature distribution during FLASH sintering
FLASH sintering is a field-assisted technique that allows the densification of ceramics in a few seconds at temperatures significantly lower than those of conventional cycles. There is still discussion among the scientific community about the mechanism behind this sintering process, that has been typically attributed to Joule heating, defect creation and movement or liquid phase assisted sintering. Computational modelling can be a powerful tool in helping to explain and predict this process. Using potassium sodium niobate (KNN) as a case study, a lead-free piezoelectric, this work explores Finite Element Modelling to evaluate the dependence of Joule heating generation and temperature distribution as a function of the cubic particle orientation
The role of particle contact in densification of FLASH sintered potassium sodium niobate
Potassium sodium niobate, K0.5Na0.5NbO3 (KNN) is a lead‐free piezoelectric with the potential to replace lead zirconate titanate (PZT) in electromechanical applications. Due to its cuboid particle morphology and volatile elements, monophasic and dense ceramics are difficult to obtain via conventional sintering. In this work, isothermal FLASH sintering produced uniformly densified KNN ceramics at 900 °C, 200 °C lower than conventional sintering. Specific surface area (SSA) analysis of pre‐FLASH ceramics revealed that a 30 min isothermal hold at 900 °C, before the application of electric field, increased the contact area between particles and was crucial to promote uniform densification. Finite element modelling (FEM) revealed why density is more uniform when using isothermal heating compared with a constant heating rate, commonly used in FLASH sintering. These results extend our understanding of FLASH sintering and illustrate its relevance for the development of lead‐free piezoelectrics
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