This study was carried out with the objective of determining the antioxidant properties and quantification of total phenolics and flavonoids in relation to quercetin and rutin in some of the ...monofloral honeys produced in Minas Gerais (Brazil). In this study, 15 monofloral honey samples were obtained from different geographic regions of Minas Gerias, Brazil. The honeys were obtained from Cooperative of Beekeepers and Family Farmers of Northern Minas. To determine the antioxidant properties of honey samples, the test methods of total phenolic content, flavonoids (rutin and quercetin) and DPPH were used. As a result of the analysis of phenolic and flavonoid contents, the samples with the best results were A1-Aroeira and A4-Assa peixe. In antioxidant activity, the honey with the best EC50 results was A6-Aroeira. Differences between the antioxidant activities of the honey samples were found significantly (p< 0.01).
Stability of rolled-up GaAs nanotubes Silva, Júnio C. F.; dos Santos, José D.; Taft, Carlton A. ...
Journal of molecular modeling,
07/2017, Letnik:
23, Številka:
7
Journal Article
Recenzirano
This work presents a theoretical study of gallium arsenide (GaAs) nanotubes obtained from the (100), (110) and (111) crystal planes of zincblende structure in order to evaluate the electronic ...properties. The DFT/B3LYP/6-31G method was used to predict structures and stabilities. It was found that nanotubes from the (110) crystal plane tended to be the most stable. The results for average diameter and bond length obtained for optimized nanotube geometries show that nanotubes constructed from the (100) plane have a hyperbolic format, while (110) or (111) nanotubes have a conical format. This difference in relation to geometry introduces regions with different charge concentrations along the tube. From the calculated values for the gap it follows that increasing the number of atoms per layer causes a displacement of the frontier orbitals with a reduction in the gap, yielding characteristics of a semiconductor material.
This study was carried out with the objective of determining the antioxidant properties and quantification of total phenolics and flavonoids in relation to quercetin and rutin in some of the ...monofloral honeys produced in Minas Gerais (Brazil). In this study, 15 monofloral honey samples were obtained from different geographic regions of Minas Gerias, Brazil. The honeys were obtained from Cooperative of Beekeepers and Family Farmers of Northern Minas. To determine the antioxidant properties of honey samples, the test methods of total phenolic content, flavonoids (rutin and quercetin) and DPPH were used. As a result of the analysis of phenolic and flavonoid contents, the samples with the best results were A1-Aroeira and A4-Assa peixe. In antioxidant activity, the honey with the best EC50 results was A6-Aroeira. Differences between the antioxidant activities of the honey samples were found significantly (p< 0.01).
•The system is a continuous real time PQ monitoring based on the concept of Digitally Enabled Substation Architecture or Substation 4.0 (SB4.0).•It presents a scalable architecture that allows the ...analysis of data from multiple substations.•It presents a practical implementation of the SB4.0 concept by proposing a novel multi-functional Substation Edge Device called here as PQMC (Power Quality Monitoring Center).•The system was installed in two substations that are part of the electrical Brazilian transmission grid. From the knowledge of the authors the system is one of the first PQ monitoring system using the concept SB4.0.•The PQMC receives voltage and current samples from a Merging Unit (MU), using the IEC 61850 Sampled Values (SV) format, and calculates various power quality parameters.•The system also provides a Data Logger application triggered by instantaneous Total Harmonic Distortion (iTHD) and by short duration voltage disturbance.•The Power Quality Monitoring and the Data Logger systems are software applications running in an industrial computer.•The System is time synchronized by GPS, providing time synchronized power quality parameters as well as waveform signals.•Results obtained from the proposed system was compared with commercial IED.•Experimental validation of the system in the laboratory and in the field.•This work is the result of a Research and Development Project with a power transmission company located in northern Brazil.•Modular architecture of the PQMC based on asynchronous queues is also a contribution of this work. This approach grants to the proposed IED a great scalability owing to the use of the single-producer multiple-consumers design pattern.•In the PQMC architecture, the signal processing routines of different channels are completely independent and do not depend on each other.•The proposed architecture allows for the modification of the PQMC features just by reconfiguring the software and without hardware changes, which is quite adherent to the SB4.0 concept.
The growth of penetration of large blocks of inverter based renewable energy in transmission power systems may lower the power quality of these systems, especially with rising of harmonic and interharmonic distortion and voltage fluctuation. Poor Power Quality (PQ) can negatively affect the protection system and may cause premature aging of electrical equipment connected to the power system. Thus, real-time and continuous PQ monitoring can be of great value for operation, maintenance and expansion of the system. This paper presents a recently implemented real-time PQ monitoring system based on the concept of Digitally Enabled Substation Architecture or Substation 4.0 (SB4.0). The proposed PQ monitoring system receives voltage and current signal samples from a Merging Unit (MU) and calculates the various power quality parameters. Since the system uses the SB4.0 concept the power quality monitoring is a software application implemented in an industrial computer. Also, the system provides a Data Recording application, running as additional software task that provide oscillography triggered by instantaneous Total Harmonic Distortion (iTHD). This paper presents the architecture of the developed and implemented system as well as the field results gathered from a transmission system in the north of Brazil.
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•The tetronamide core is present in compounds displaying varied bioactivities.•The reactivity of tetronamides allows their functionalization, providing chemical diversity.•This review ...covers syntheses and functionalization of the tetronamide core.•Structure-activity relationship of some tetronamides is discussed herein.•Tetronamides include the insecticide sivanto® and potent antitumoral compounds.
Butenolides and tetronic acids occupy a prominent position in synthetic chemistry due to their ubiquitous distribution in nature. This has stimulated investigations firstly in the synthesis of such systems and, laterly, the interest has turned to the understanding of the quantum structure of such systems, allowing a deeper understanding of the mechanism and reactivity of this cyclic scaffold. In contrast, tetronamides, which consist of compounds bearing a 4-aminofuran-2(5H)-one backbone, are relatively rare in nature and synthetic routes to such compounds are poorly explored. This review highlights both the importance of the tetronamide scaffold in medicinal chemistry and the most relevant recondite synthetic strategies for obtaining compounds of this class.
Meloidogyne incognita
is one of the most important plant-parasitic nematodes (PPNs) causing severe crop losses worldwide. Plants have evolved complex defense mechanisms to respond to PPNs attacks. ...Conversely, PPNs have evolved infection mechanisms that involve the secretion of effector proteins into host plants to suppress immune responses and facilitate parasitism. Therefore, effector genes are attractive targets for the genetic improvement of plant resistance to
M. incognita
. In this study, we functionally characterized the
Minc16803
(
Minc3s00746g16803
) putative effector gene to evaluate its role during plant-nematode interactions. First, we found that the
Minc16803
gene is expressed in all nematode life stages and encodes a protein with an N-terminal signal peptide for secretion, a motif characteristic of effector proteins and with the absence of transmembrane domain. In addition, our data demonstrated that transgenic
Arabidopsis thaliana
lines overexpressing a
Minc16803
-dsRNA efficiently downregulated the
Minc16803
transcripts in infecting nematodes. Furthermore, transgenic lines were significantly less susceptible to
M. incognita
compared to wild-type control plants. The number of galls per plant was reduced by up to 84%, while the number of egg masses per plant decreased by up to 93.3%. Moreover, galls and feeding sites in the roots of transgenic lines were smaller than those in the control plants. Histological analysis revealed giant cells without cytoplasm, disordered neighboring cells, and malformed maturing nematodes in transgenic galls. Curiously, numerous hatching ppJ2 juveniles were often observed near the female body within the transgenic root tissues before egg mass extrusion. All findings strongly suggest that
Minc16803
gene is a promising target to engineer agricultural crops for
M. incognita
resistance through host-induced gene silencing.
This article presents a study on the use of natural fibers and kaolin waste as sustainable alternatives in the manufacture of polymer matrix composites. In the present research, isophthalic ...unsaturated polyester matrix composites were manufactured in association with bamboo fibers (Bambusa vulgaris) and kaolin waste. The kaolin waste was used with a particle size of 50–100 MESH and the fibers in lengths of 15 mm and 30 mm, randomly arranged within the matrix. Bamboo fibers were used fresh and treated with NaOH (5%/2 h). The chemical characterization of the fibers was obtained followed by the morphological characterization using Scanning Electron Microscopy (SEM). The composites were mechanically evaluated through flexural and tensile tests. The mechanical properties obtained were treated by analysis of variance (ANOVA) and Tukey test. The fracture surfaces of the composites were verified by SEM. Bamboo fibers had a chemical composition similar to other natural fibers already studied, with 7.55% extractives, 17.95% total lignin and 74.5% holocellulose. Composites with 30 mm long treated fibers and 30% kaolin showed better flexural strength (137.0 MPa), with deformation of (1.59 mm) and flexural modulus of (19.27 GPa). Through tensile tests, it was possible to identify that the addition of kaolin waste provided a significant improvement in tensile strength of 66% (15BTKW20) and 54% (30BTKW20) compared to neat polyester. SEM micrographs of bamboo fibers, surface roughness, starch granules, micropores and parenchyma cells were identified. ANOVA reinforced the reliability of the results, highlighting the feasibility of manufacturing kaolin waste/bamboo fiber hybrid composites.
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This work presents an experimental investigation of the mechanical properties of composites reinforced with crocheted fabrics of miriti fibers (Mauritia flexuosa) in a polyester matrix. The fabrics ...were manufactured under different grammages, with and without alkaline fiber treatment. The composites were produced using two different viscosity conditions of the polyester matrix and part of these underwent post-cure treatment at 60 °C. In order to evaluate the effects of the input variables, the samples were produced by manual lamination with curing under vacuum, following a complete factorial experimental matrix type 24, tested according to the ASTM D 3039. The results showed that the variables alkaline treatment of the fibers and viscosity of the matrix presented statistically significant effects on the responses limit of tensile strength and modulus of elasticity. The highest level of tensile strength (13.02 MPa) was obtained in composites with alkaline treatment of the fibers, fabric grammage 473.9 g/cm2, matrix with higher viscosity and post-cure application, while the modulus of elasticity obtained the best performance (1.59 GPa) in samples without alkaline treatment of the fibers, manufactured with the fabric of lower grammage, with a more viscous matrix and that underwent post-curing.
The Atlantic gollath grouper is a critically endangered species that inhabits estuarine and reef environments and is threatened primarily by fishing activities and habitat destruction. Despite the ...urgent need for protection, its genetic conservation status remains unknown. The aim of the present study was to evaluate the gene flow among the populations of the species along the coast of Brazil based on the control region of the mitochondrial DNA. The results indicate low haplotype diversity and very low nucleotide diversity. They also show that the genetic diversity of the species varies considerably along the coast and that this finding may be especially important for the identification of priority areas for its conservation. The results of this study suggest that, though it may be incipient, the observed genetic structuring must be taken into account in order to prevent potential problems, such as out-breeding depression, in the management of wild stocks.
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