Ciência e Natura

Drying study and phytochemical profile of the aqueous extract of the scaly leaf bulb of Allium cepa L (var.roxa)

2023-11-16T09:41:59-03:00

The objective of this study was to evaluate the phytochemical profile, predict drying kinetics, and quantify the content of total phenolics and flavonoids present in the aqueous extract of the bulb of scamiform leaves of Allium cepa L. The plant material was collected in the municipality of São Luís (MA). For the preparation of the aqueous extract, the cold maceration process was used using distilled water as a solvent. For the study of the drying kinetics, 10 g of the material in natura was submitted to a convective air oven at 45 °C/4h. The statistical parameters were determined by nonlinear regression using the Statistica 10.0software, using the Quasi-Newton method. To determine the total phenolic content, the Folin-Ciocalteu methodology was used. And for the total flavonoids, the aluminum complexation assay was used. The determination of phenolics and total flavonoids revealed significant quantities in the extract, with values of 106.54 mg EAT g-1 and 26.36 mg EAT g-1, respectively. According to the prediction of the statistical data, it was verified that the mathematical methods of Midilli-Kucuk and Verma proved to be adequate to describe the drying process of Allium cepa L. Through the results obtained, the mathematical model was determined for the drying kinetics of the squamous leaf bulb Allium cepa L, in addition to attesting the presence of secondary metabolites, thus making the product fit for biologically active activities.

Eco-friendly strategies for the graphene oxide reduction

2024-01-12T09:21:58-03:00

The reduced graphene oxide (rGO) is a nanomaterial derived from graphene, which exhibits a high surface area, chemical stability, and extensive diffusion of π-conjugated bonds. Graphene oxide (GO) can be reduced to rGO through different protocols, however, commonly applied methodologies involving the use of chemical reagents may have disadvantageous effects on the environment. Considering the excellent properties of rGO, this study aimed to reduce GO through sustainable green strategies using carrots, oranges, and beets as reducing agents. The characterization of GO and rGO was carried out by X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electronic microscopy (SEM), which revealed a reduction in the spacing between the layers of GO, indicating the formation of rGO. Due to the outstanding results obtained, future studies will explore the properties of this nanomaterial as an adsorbent for contaminants of emerging concern.

Nanoemulsions of plant-based bioactive compounds with antimicrobial applications: a review

2023-10-27T09:37:48-03:00

The search for alternative antimicrobial agents is attracting increasing scientific interest. Natural products of plant origin are sources of several substances with proven biological activities, including antimicrobial activity. The encapsulation of these products in the form of a nanoemulsion seeks to overcome problems inherent to these products, such as instability and degradation. Based on these considerations, we carried out a bibliographical survey of nanoemulsions produced from plant-derived substances, such as essential oils and extracts, with antimicrobial potential, focusing on antibacterial, antifungal and antiviral activities. Articles and documents published in scientifically relevant journals, as well as keywords classified from Health Sciences Descriptors, were used. All documents relevant to this search reported that nanoemulsions loaded with essential oils and plant extracts from different botanical species had in vitro antimicrobial activity against different microorganisms of medical importance, in addition to enhancing the antimicrobial effects of these bioproducts. Therefore, nanostructured antimicrobials with essential oils and plant extracts can be considered treatment options for microbial diseases: due to their physicochemical properties, they act as better delivery vehicles for natural products with good bioavailability, by reducing toxicity and prolonging the useful life of these natural antimicrobials, thus enhancing treatment for infectious human diseases.

Making chocolate sweets and the statistical analysis of experimental data

2023-05-09T20:48:59-03:00

This is a didactic proposal for the introduction of data processing concepts using typical Brazilian chocolate sweets, called brigadeiros. The methodology consisted of distributing a packaging of brigadeiro to each of the groups: blue, orange and green. The groups had to make the brigadeiros in the dimensions they wanted, proceeding with their quantification and weighing. Statistical analysis was based on hypothesis tests (p<0.05) in which the average mass of sweets obtained by the groups was compared in relation to the reference value and the performance of the groups among themselves. It was observed that 29, 20 and 16 sweets were made with average masses of 16.4±2.2; 24.6±4.5 and 28.5±8.7g for the blue, orange and green groups, respectively. The groups' precision and accuracy were blue>orange>green. The unpaired t-test, confidence interval for the mean and ANOVA suggested a significant difference between all groups. However, Tukey's test identified only the brigadeiros in the blue group as different from the other groups. In addition to the insertion of statistical concepts, carrying out this didactic proposal can stimulate teaching practice, involving the student and promoting meaningful learning. This experiment is fast, practical and inexpensive, and can be applied at any level and/or area of knowledge.

Penny Circle: a study of the Quadratic Function

2023-09-04T16:19:45-03:00

This work aims to present and discuss a pedagogical proposal involving the teaching of Quadratic Function, aimed at high school students. This is research with a qualitative approach, and is supported by the assumptions of mathematical research (Ponte et al., 2019). The activity arose from a reflection on the following question: how could the student recognize the graph of a Quadratic Function in a problem situation, using concrete material? Based on this proposal, the teacher can reflect on the teaching of functions and encourage the student to establish relationships between objects and mathematical problems that, through concrete material, allow experimentation and verification of conjectured results. In addition, review the contents of Affine Function, System Resolution, Radicals, Exponential Function, discuss the concepts of domain, codomain, range and properties of the graph of functions.

Use of green vegetable barriers as environmental noise attenuators: a case study in Irati, Parana

2023-05-09T09:10:23-03:00

The present study aims to evaluate the potential of the Secondary Mixed Ombrophilous Forest as a vertical noise-attenuating green barrier. The methodology calls for the development of an analysis of proximity between sampling points of omnidirectional noise monitoring to be measured at various distances from the source from the beginning of the barrier and inside the forest. A sound source reproducing amplified pink noise was used. In this research, an experimental strategy was used to prove the influence of this type of green plant barrier as a noise attenuator as one enters the interior of a fragment of Mixed Ombrophilous Forest, carrying out successive measurements of the sound pressure level at distances from the proximity of the source and the distances from the edge towards the interior of the forest that can prove the significant attenuating function of this type of green vertical barrier. In fact, the analyses performed for LZeq A and Z (dB) confirm a significant correlation for distance from the source regardless of the sound amplitude for measurements performed outside the barrier (in front of the source, 6 m behind the source, 6 meters in front of the source), as noise attenuation occurs as the sound propagates. However, the analyses inside the barrier (at 12m, 18m and 24m) present a negative correlation for distance, confirming the hypothesis of the effectiveness of the attenuation by the vegetal barrier.

Seasonal climatology of cold fronts in south-central South America from an automated detection system

2023-10-31T15:26:57-03:00

The cold fronts (CF) operating in south and south-central South America are the main ones responsible for heavy rain, thunderstorms with strong winds, and accentuated temperature drops. This study aimed to perform a seasonal climatology of CF’s displacement and intensity in the region above mentioned. A computational algorithm was developed called the Normalized Cold Front Detection Index (NCFI) for detecting and characterizing CFs through the CFSR and CFSv2 reanalysis data, using the meridional component of the wind at 10 meters and the air temperature at 2 meters. Ten areas were delimited: five coastal and five continentals. Seasonal climatology showed a higher frequency in winter, when these systems are more intense, averaging 20 per year. The patterns of displacement and intensity exhibited a decrease in CFs as they advanced toward lower latitudes. The synoptic analysis and the accumulated precipitation composites revealed that the CFs that act in the spring concentrated the accumulated precipitation in Santa Catarina’s western portion. In the summer, convection cells are responsible for storms and poorly distributed rain. In the autumn, rainfall is associated with CFs and maritime circulations, impacting Rio Grande do Sul and the west and north of Santa Catarina. In the winter, CFs dominate the precipitation pattern. According to the NCFI, spring, autumn, and winter cases are categorized as intense, while summer cases are moderate.

Aflatoxin M1 in milk and dairy products in Brazil: a review of characteristics, contamination, human exposure and health risks

2023-05-22T19:51:23-03:00

This paper aimed to present a review of the presence of aflatoxin M1 in milk and dairy products in Brazil, along with its characteristics and potential risks to human health. Overall, most studies analyzed during the defined period of this review (2013 to May 2023) reported average concentrations of AFM1 within the limits established by Brazilian legislation for milk, powdered milk, and cheese. However, considering the consumption of milk and dairy products by more vulnerable groups, such as children, two studies reported levels of AFM1 above the limits established for aflatoxins in different regions of Brazil. Thus, a more rigorous inspection by the responsible Brazilian authorities is necessary. Furthermore, since AFM1 is the only mycotoxin present in milk relevant to public health, it is important to continue conducting studies on the detection and determination of aflatoxins in milk and dairy products. This is necessary to monitor these contaminants and estimate the levels to which the population is exposed.

Adsorption study of micropollutants by biosorbents from different rice harvest residues for large scale applications

2023-09-21T08:32:12-03:00

A large-scale removal of micropollutants from residual waters is an urgent problem to be tackled. In this work, three biomasses from agricultural residues, produced by different processes, were compared in terms of the adsorption efficiency of toxic species in water. The biosorbents used were rice husk ashes (RHA), leached rice husk silica (SRHA), and rice straw ashes (RSA). Two representatives of the most common micropollutants present in the effluent waters, 2-nitrophenol and the pesticide 2,4-dichlorophenoxyacetic acid (2,4-D), were chosen as probing molecules. The biosorbents were characterized by SEM, X-Ray FRX, FT-IR, BET, pHcpz, and hydrophobicity; surface areas of 175.81 m2 g-1(SRHA), 66.11 m2 g-1 (RHA) and 42.77 m2 g-1 (RSA) were found, together with a microporous morphology. Firstly, the efficiency of removal was evaluated through adsorption isotherms: RHA and SRHA proved to be more efficient, with an adsorption capacity of 29.14 mg g-1 and 23.75 mg g-1 of 2-nitrophenol and 10.82 mg g-1 and 10.55 mg g-1 for 2,4-D. In particular, the removal of more than 90% for both 2-Nitrophenol and 2,4-D stands out as a very promising result. In light of these results, pillow-shaped filters with RHA were fabricated and tested for the first time for 2-Nitrophenol removal on a larger scale. The positive outcome (removal efficiency of 73%) demonstrates the possibility of producing filters based on sustainable and cheap biosorbents that could be implemented industrially to improve water purification as well as to implement the concept of circular economy.

Graphene oxide assessment on the germination of Persian clover and buckwheat seeds

2023-06-30T09:00:15-03:00

The increase in the use of graphene oxide (GO) allows different studies in several fields, and raise concerns about its possible toxic effect on the environment, especially in the early growth of plants. Thus, this study aimed to evaluate the effect of GO on the germination of Persian clover and buckwheat seeds. The seeds were placed on germitest paper in different concentrations of graphene oxide (0, 125, 250, and 500 mg L^-1) and kept in a germination chamber at 20 °C (photoperiod of 12 hours). The evaluated parameters were seed germination and seedling growth (length and dry mass). Graphene oxide did not show toxic effects on seed germination and initial growth of both species up to 500 mg L^-1. In this context, understanding the role of graphene oxide in the germination process and the development of plants will be able to contribute positively to understanding its possible environmental impacts when used in large quantities in ecosystems.

The use of maximum correlations of TSM of the atlantic dipole and precipitation in the state of Ceará

2024-04-26T15:50:02-03:00

It is known that the relationship between the ocean and the atmosphere is a major precursor of a wide range of meteorological events that influence the entire globe, including the rainfall regime in various regions. Understanding how these events explain precipitation is of constant interest. In this sense, the present work aimed to determine the maximum correlations between the Surface Sea Temperature (SST) anomalies in the Atlantic dipole region and precipitation in the State of Ceará. For this, we used observed and interpolated data of daily precipitation and SST anomalies from the National Oceanic and Atmospheric Administration (NOAA) for the period from 1982 to 2021. Using a tree algorithm between the maximum correlations of the Atlantic Dipole, based on in daily SST data, and precipitation we propose a methodological proposal to predict precipitation in the State of Ceará.

Spatial distribution of soil loss tolerance limits for the state of Paraíba using GIS

2023-06-30T10:27:01-03:00

Changes in the physical and chemical attributes and biological processes of the soil over a long period of time lead to loss of ecosystem function and agricultural productivity. This work aimed to estimate, classify and map the soil loss tolerance limits for the lands of the State of Paraíba based on the values of the different soil classes, with variation in thickness of horizons and textural relationship, using modeling of geoprocessing data and techniques. The estimate was based on the effective depth, texture and density of the soils described in the 64 profiles from the Exploratory and Soil Recognition Survey and the Agricultural Zoning of the State of Paraíba and calculated using the Smith and Stamey (1964) method and using QGIS© for mapping. Soil loss tolerance followed the order of Oxisols > Cambisols > Argisols > Luvisols > Planosols > Neosols > Vertisols due to the influence of parameters such as effective soil depth and textural relationship between B and A horizons. Soil loss tolerance presented in the very high class an average of 20.08 t ha-1 yr-1 and are associated with Oxisols, Argisols, Cambisols, Planosols and Gleissoils. The upper class presented average losses of 10.56 t ha-1 yr-1 under Argisols. The tolerance limit for losses in the middle class was 6.59 t ha-1 yr-1 distributed under the Luvisols. The low class occurred in Luvisols, Planosols and Neosols distributed in 389 mapping units with an average limit of 3.90 t ha-1 yr-1; in the very low class it occurred under the Vertisols, Nátric Planosols and shallow Neosols with an average of 1.64 t ha-1 yr-1 of soil loss tolerance distributed in 362 mapping units.