Resumo em Inglês:

Methanol (CH3OH) is one of the most abundant organic molecules in astrophysical environments. It has been found in cold regions such as surfaces of comets, ices near young stellar objects and protoplanetary disks, as well as in the gas phase in different regions in space. In this work, we experimentally simulate the methanol ice and its behavior when irradiated by broadband soft X-rays. The experiments were performed at the Brazilian Synchrotron Facility LNLS/CNPEM, employing a broadband photon beam (6 to 2000 eV). The frozen sample was analyzed in situ by infrared spectroscopy (IR) in simulated astrophysical at different radiation fluences. The results show the formation of several new species such as CO2, CO, H2O and CH4 during the photolysis CH3OH ice by soft X-rays. We determined effective destruction and formation cross-section, as well as the chemical equilibrium fluence (FE) and desorption yields. The timescale to reach chemical equilibrium in some astrophysical environments with soft X-rays were estimated. The result helps us to understand the photolysis induced by X-rays in organic-rich ices in space environments.

Resumo em Inglês:

The molecular dynamics simulations were used to study the epoxy ring-opening in the determination of kinetic parameters, with a temperature range from 1500 to 2500 K in a 20 x 20 x 20 Å unit cell containing 15 molecules of C2H4O (ethylene oxide) and 35 molecules of CH6N2 (methanediamine). The activation energy values for epoxy and diamine was 66 and 92 kJ mol-1, respectively. The simulation showed epoxy ring breakage in some of the molecules, but mainly the release of ammonia by diamine. It was observed that the activation energy involved in diamine consumption for ammonia formation is higher than for the epoxy ring opening. The results of the epoxy ring-opening study show that the polymerization occurs slowly, which leads to high computational simulation values.

Resumo em Inglês:

Considering the size of the Amazon region and the need for studies to establish soil trace metal concentrations in natural environments, the objective of this work was to evaluate heavy metal contents in a toposequence of an Amazon State microbasin. Soil samples were collected in three native forest topographic positions. Samples were opened for analysis by two methods: exchangeable cations were determined by the silver thiourea method and total metal elements by sulfuric acid. The metals were determined by atomic absorption spectrometry. In general, it was observed low concentration of several elements considered essential to plant growth in the studied soils, indicating low concentration in the source material of these soils and the intense weathering leaching. The higher concentrations of heavy metals found in the Plateau / Shed areas may be related to clay soils and more acidic pH than other topographies. Exchangeable Al was found at higher concentrations, while Na was the element with the lowest concentration. Total metallic elements presented higher availability potential in the Plateau / Shed areas, except for B, Cr, Mo and Ni. These differences justify the development of regionalized studies for heavy metals in soils appropriate to the conditions of each environment.

Resumo em Inglês:

Fire investigation is a complex activity that involves skill, technology, knowledge and science and aims to elucidate fire-related events such as cause, origin, propagation, phenomena, etc. Chemical analysis to verify the presence of foreign substances in that location, as well as the use of fire simulation software are efficient and economical ways to study fire behavior during the occurrence of fire. This work demonstrates the application of Gas Chromatography coupled to Mass Spectrometry (GC-MS) in the analysis for gasoline and diesel identification in different substrates, as well as the application of computational fluid dynamics (CFD) to aid in the elucidation of fires. The chemical analyses performed showed the possibility of identifying the presence of accelerants even in small quantities (1 µL) and in different types of materials (wood, polyethylene, polyurethane, polyamide and newsprint). The computational model generated by the software proved to be consistent with the data obtained at the scene by the fire expert, thus serving in the hypothesis discard and conclusion of the investigation.

Resumo em Inglês:

Spectroscopic techniques are powerful tools for molecular organic matter assessment in sediments, which analysis request low sample mass and are cheap, fast and easy to obtain. The aim of this work was to evaluate the elemental (C, N) and molecular composition of the organic matter in relation to the grain-size distribution over surface sediments from Sepetiba Bay. Spatial distribution of grain-size was remarkable heterogeneous, with the internal area presenting the highest levels of fine sediments, organic carbon (0.20-3.45%) and total nitrogen (<LQ-0.36%). Concentrations of organic carbon from surface sediments at the study area seem to be lower when compared to other degraded coastal systems. C/N ratio vary between 10 and 20, suggesting a mix of allochthonous and autochthonous sources of organic matter to the sediments. DRIFT spectra presented prominent and marked bands assigned to organic and mineral functional groups bonding and the spectra identified chemical bonds of molecular composition such as aliphatic and aromatic functional groups.

Resumo em Inglês:

Salacia crassifolia traditionally known as “Bacupari-do-Cerrado” is used to treat kidney problems, and as a healing agent for coughs and malaria. The phytochemical study of the S. crassifolia roots led to the isolation of thirteen compounds: abruslactone-A (1), urs-12-ene-3β,25,30-triol (2), carioprystimerin (3), β-sitosterol (4), pristimerin (5), dispermoquinone (6), netzahualcoyonol (7), 20-hydroxy-20-epi-tingenone (8), 6-oxo-pristimerol (9), 9β,10β-epoxi-3β-hydroxy-1βH,4βH,5βH,7βH,11αH-guaian-12,8β-olide (10), 3-O-b-D-glucosyl-b-sitosterol (11), 4`-O-methylepigalocatechin (12) and cerebroside (13). The chemical structures of 1-13 were determined by IR, 1D/2D NMR together with X-ray diffractometry. Compounds 2 and 10 are herein described for the first time. Extracts of S. crassifolia and compounds 3, 5, 8 and 9 were evaluated on acetylcholinesterase inhibition, in vitro cytotoxic activity and in vivo toxicity tests using Caenorhabditis elegans model. All tested compounds inhibited acetylcholinesterase, and compounds 3, 8 and 9 demonstrated a greater potential when compared to the standard eserine. The tested compounds showed low cytotoxicity against the THP-1, K562 and MDA-MB-231 cancer cell lines. None of the tested compounds and extracts were toxic against C. elegans since the larvae survival rate in L1 stage was higher than 90%.

Resumo em Inglês:

Phytochemical investigation of the inflorescences of Dictyoloma vandellianum A. Juss. (Rutaceae) has led to the isolation of a new A-seco-limonoid, named dictyolomol (1), along with a known quinolone alkaloid, casimiroine (2), previously isolated from the same species. The structures were established by spectroscopic analysis such as one- and two-dimensional NMR, IR, high-resolution mass spectrometry and chemical transformations. The isolated compounds (1 and 2) and O-acetyl derivative (1a) were evaluated for their cytotoxicity against MCF-7 and HeLa cancer cell lines. The results indicated that 1, 1a and 2 showed no significant cytotoxicity.

Resumo em Inglês:

Production of bacterial nanocellulose was pursued as a matrix system for the stabilization of human insulin. The biomembranes produced by Gluconacetobacter hansenii were washed with 2% aqueous sodium dodecylsulfate solution, rinsed with ultrapure water and immersed in 1 mol L-1 NaOH aqueous solution at 60 °C for 90 min until neutralization. For the insulin adsorption assays, the biomembranes were soaked in a buffered solution of human insulin until no protein could be detected in the supernatant. The membranes with adsorbed insulin were characterized via mechanical resistance (resilience, relaxation, perforation), Differential Scanning Calorimetry (DSC), Thermal Gravimetrical Analysis (TGA), Fourier Transform Infrared Spectrophotometry (FTIR), X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) analyses. The FESEM photomicrographs of the surface of the biomembranes showed a rugged surface without cracks. The biomembranes exhibited adequate mechanical characteristics. The infrared spectra indicated that the chemical aspect of the protein moiety was preserved during adsorption onto the BNC biomembranes. According to the XRD analyses, the biomembranes showed a generalized amorphous behavior. Thermal analyses indicated an adequate thermal stability for a pharmaceuticals product. Hence, an elastic and malleable biomembrane was produced, suitable for incorporation of human insulin, aiming at transdermal delivery.

Resumo em Inglês:

In this work, the peels of ripe banana (Musa sp.), variety “Prata”, were used to prepare a flour, which was evaluated for its physicochemical characteristics and antioxidant activity. The characterization of its chemical profile was performed by a fast and simple method: paper spray-mass spectrometry. This flour had high carbohydrate content and total dietary fiber, and significant amount of total phenolic compounds with antioxidant activity. In addition, this flour exhibited higher water-holding, oil-holding and swelling capacities than those of fruit by-products reported in the literature. Fourier-transform infrared spectroscopy confirmed the presence of functional groups of cellulose, hemicellulose, and lignin, constituents of insoluble dietary fiber. By the paper spray-mass spectrometry technique, it was possible to suggest the presence of 26 substances such as organic acids, phenolic acids, flavonoids, sugars, quinones, and terpenoids. Thus, this study demonstrated that the ripe banana peel flour has potential application as an ingredient for functional foods.

Resumo em Inglês:

By way of Density Functional Theory (DFT)-based computational methods with commercially available software, the computational work of which about the molecular properties, the vibrational modes and vibrational frequencies of finasteride were accomplished for the first time. In order to gain a deeper and more thorough understanding of the molecular structure and infrared spectrum of finasteride, the equilibrium geometry harmonic vibrational frequencies and geometric parameters (bond lengths, bond angles and dihedral angles) were calculated by Generalized Gradient Approximations (GGAs) with five different density functional methods (PBE, RPBE, HCTH, PW91 and BLYP), using Material Studio 8.0 program. Theoretical vibrational frequencies and theoretical optimized geometric parameters were compared with the corresponding experimental data, which concluded that the GGA/PW91 method were shown to be in a good agreement with the results of experiment. In addition, the highest occupied molecular orbital (HOMO) energies, the lowest unoccupied molecular orbital (LUMO) energies and electron density isosurface calculations were done with an aim at a better understanding of the stability and reactivity of the molecule, indicating that the alkene and lactam conjugated system on the ring A is more likely to interact with other species. And, the atomic charge distribution was also calculated to understand the charge effect caused by electronegative atoms, which shows that the possible active-sites in chemical reactions are N1 and O1.

Resumo em Inglês:

The emergence of antibiotic resistance among microbial pathogens is a serious public health problem, resulting in a constant need of discovering new antibiotics. For this purpose, we synthetized and determined the antimicrobial activity of copper (Cu), cobalt (Co), and tin (Sn) complexes coordinated with scorpionate ligand in a tridentate mode against microorganisms of clinical importance. New complexes with the sodium hydrotris(2-mercaptothiazolyl)borate ligand were characterized by physicochemical and spectroscopic techniques (UV-vis, IR, 1H and 13C NMR). Moreover, their antimicrobial activity was evaluated using microdilution broth method. Cytotoxicity was determined in Vero cells and the selectivity index (SI) was calculated. The coordination with metals increased the ligand antimicrobial activity, which showed no activity when evaluated alone (MIC>1,080 µM). Cu-complex (1) had activity against Candida albicans and C. krusei, with MICs of 130 and 66 µM, respectively. The compounds had low toxicity on Vero cells and chemo-informatics assays corroborated a low systemic toxic effect. The SI revealed that the compound 1 was 16 times more selective for C. krusei and 8 times more selective for C. albicans in relation to Vero cells. The Cu-complex stands out as a potential prototype for the development of new antifungal agents.

Resumo em Inglês:

The present work proposed the application of a multivariate regression model based on image data to monitor the decolorization process. Thus, a PLS regression based on the color histogram was applied to monitor the methylene blue degradation by the Fenton reaction. The results obtained by the digital imaging and UV-Vis methods were compared and the initial (Cº) and final (C) methylene blue concentrations, as well as the kinetic parameters, coefficients of determination (R2), half time degradation (t½), intercept (ρ), and slope (σ), were evaluated. From our results, the digital imaging and UV-Vis methods have equivalent potential to monitor the color removal profile, similar kinetic term, and low measurement errors. While the coefficient of determination (R(2)) of all PLS models and kinetics curves are close to 1.00, the half time degradation (t½) parameter ranged between 0.29 to 1.39 min for the UV-Vis model, and 0.80 min to 2.17 min for the digital imaging model. Furthermore, the efficiency of methylene blue removal ranged between 92.04% and 97.78% for the UV-Vis model and 91.30% to 93.72% for the digital imaging model. Then, based on statistical comparison tests, it was concluded that the digital imaging method is an alternative to monitor dye degradation processes.

Resumo em Inglês:

Glutathione Reductase (GR) plays a key role in the maintenance of GSH homeostasis, variations in its activity may indicate damage from environmental contaminants. Experimental planning is a strategy to reduces time and cost in enzymatic assays. In this work, DCCR experimental planning was used to standardize and to validate the measure of GR in Aegla singularis bioindicator. Samples of A. singularis were collected in three watersheds with different percentages of naturalness and land uses. At all, were selected 7 streams, in which collections were performed at one upstream (most preserved) and one downstream (less preserved) point. Effects of temperature, reading time, substrate (GSSG) and protein concentration in GR reaction medium were evaluated, being that the two latter variables were optimized by DCCR. GR was not affected by temperature (15 to 30 °C) or reading time (6 and 10 minutes). Increased concentrations of proteins from biological extract had negative correlation with GR, whereas higher concentrations of GSSG resulted in higher GR activity. Environmental validation showed that GR in Aeglawas influenced primarily by the watershed of origin. DCCR planning was efficient to optimizing the use of GR as a biomarker of environmental quality.

Resumo em Inglês:

Electrospinning is a strand of nanoscience for the production of fibers in nano and micrometric scales and when combined with other techniques it becomes a powerful tool for application in various branches of science. A promising combination of electrospinning is photodynamic therapy (PDT) and photodynamic inactivation of microorganisms (PDI) for the manufacture of fibers with photoactive characteristics that can be used with great ease in the medical field. This systematic review reports technical information, preparation and characterization of nano and microfibers obtained by the electrospinning technique with applicability in PDT/PDI.

Resumo em Inglês:

The remediation of contaminated soil and water is a relevant topic, being the focus of intense research. The use of nanoparticles to degrade contaminants has been consolidated as a sustainable remediation technology, with promising results worldwide. In this scenario, the zero-valent iron nanoparticles (nZVI) which, due to their properties, prove to be an important element to be used in remediation techniques, in addition to being efficient and low cost. In this article the objective is to present a bibliographic review on nanotechnology applied to soil and groundwater remediation, especially the application of nZVI, considering its main characteristics, reactivity performance, pollutants that can be degraded, application and transport techniques and main advantages and disadvantages. Issues related to toxicity and factors related to in situ applications are also presented. It is considered the results that have been observed, there is feasibility for the research to intensify even more, due to the efficiency of this nanomaterial on pollutants present in soils and waters, and it is important to expand the studies in Brazilian soils, since most of the research is international, and it is not possible to directly transfer knowledge acquired from temperate soils to residual soils of tropical and subtropical climate.

Resumo em Inglês:

This work aims to develop a rapid and reliable method by HPLC-QqQ-MS/MS for identification and quantification of Kaurenoic acid (KA) in extract, tincture and syrup from Mikania glomerata. The developed method allows identifying and quantifying KA in complex samples obtained from extract marketed in pharmaceutical industry, a tincture prepared with the leaves from plant and two syrups purchased in the local market. The quantification was performed using standard addition calibration curve. An accurate method for Kaurenoic acid determination in M. glomerata samples was developed. The concentrations of KA found in M. glomerata were 0.19 mg mL-1 in the commercial extract, 0.93 mg mL-1 in the tincture, 3.00 x 10-3 mg mL-1 in the syrup B and in syrup A was not possible to quantify due to the concentration is below the detection limit. Since most reports describe the quantification of the main active constituent (coumarin) and do not provide relevant information on the quantification of KA in these sample types (syrup and tincture), the developed method represents an excellent alternative for agile and efficient analysis of the KA in complex matrices from simple dilution.

Resumo em Inglês:

Scientific reports are important tools for show results of experimental activities undertaken at undergraduate level. The aims of this research were detecting difficulties of undergraduate students in the elaboration of reports in the experimental chemistry subjects of students of the Science: Biology and Chemistry course at the Federal University of Amazonas in different periods (2nd to 10th). Results and discussion and theoretical bibliographic were topics reported with the most difficulty. The students showed little reading habit, however, which increases with the time they spend in university, also reflecting the retention rate in the experimental subjects. These results point to possibilities to reduce the difficulties in the elaboration of experimental reports by intervention alternatives more appropriate to the desired learning process, based on the students’ reality. Detecting these points becomes an important to assist them in the learning process of academic writing.

Resumo em Inglês:

Several scientific works demonstrate the chemical and medicinal importance of hydrazone compounds. In this regard, the present paper proposes some practical classes of chemoinformatics and organic chemistry, using investigative and illustrative strategies, to teach the synthesis of a hydrazone and a N-acylhydrazone with proven biological activity. The motivating element used for the development of this didactic material was the use of commercial drugs, such as hydralazine and isoniazid, as alternative reagents for the synthesis of the target compounds. The sequence of experimental classes was planned to demonstrate the role of chemistry in the development of new drugs, to estimulate the curiosity of undergraduate students and to facilitate learning and the assimilation of the contents.

Resumo em Inglês:

Innovation and multidisciplinarity are the way to accelerate improvements in education, as well as the search for contextualized content. The multidisciplinarity between chemistry and Biology, allows to explore various contents, one of them is the environment. Works that offer alternatives to simpler experiments are of great help professors. In this context, this study suggests a didactic sequence using easily accessible materials to address chemical and Microbiological concepts of soil. The proposal is aimed at high school students and early undergraduate students. The contents were: hydrogen potentials (pH), mixture separation methods, soil liquid and gas phases and soil microbial population extraction involving bacterial DNA. Thus, the work shows a low cost alternative for the teaching of concepts related to soil, being a contextualized, multidisciplinary, dynamic and attractive proposal.

Resumo em Inglês:

The polymer demand for geotechnical applications has been growing. The geomembrane is a geosynthetic, manufactured, polymeric product and is often specified in environmental projects. Geomembranes started to be used in the 1930s but became more widespread in the 1940s. In the 1970s, geomembranes began to be specified for landfills. Over the past forty years, millions of square meters of HDPE geomembrane have been used in different applications. One of the most important issues for HDPE geomembranes is durability, involving very long-term property requirements. A rupture in the liner that has a geomembrane may provide losses in terms of human lives, environmental impacts, and financial costs. This paper summarizes the mechanisms and concepts involved in the HDPE geomembrane aging and describes the important contributions of laboratory and field studies over the years around the world. Different conditions and exposures drive the HDPE geomembrane behavior, including field temperature conditions and contact with different chemical substances. Accelerated laboratory testing with HDPE geomembrane simulating field boundary conditions is critical to ensure proper use of this geosynthetic in the future.

Resumo em Inglês:

In December 2019, the first case of severe acute respiratory syndrome (COVID-19), caused by the new coronavirus (SARS-CoV-2) was reported and the disease was declared as a worldwide pandemic in March 2020. As there is no vaccine currently available, the daily hygiene cleaning habits and social distance are the ways to fight COVID-19 indicated by the WHO. Hand and surface hygiene has become essential and the use of 60-90% ethanol is recommended for its effective biocide action. Phenol-based products are effective sanitizers, but they can cause irritation and are not recommended for surfaces that come into contact with food. There are quaternary ammonium salts that present low toxic and are good sanitizers, as they can cause the denaturation of proteins and disruption of viral lipid bilayer. Sodium hypochlorite is one of the most used sanitizers due to its low cost and effective oxidative capacity. In the same direction, peroxides are also used as a biocide, as they cause oxidation of lipids and denaturation of viral proteins. The goal of this paper is to describe the action modes and chemical concepts of the sanitizers recommended by the ANVISA-Brazil to be used against the new coronavirus.

Resumo em Inglês:

The recent coronavirus pandemic has already victimized hundreds of thousands of people around the world, and until this moment does not exist any medicine for healing or vaccine to avoid the contamination. Therefore, the actions of social isolation associated with the use of masks and surface and hand sanitation are the most effective actions to avoid the virus dissemination. The hands are one of the main vectors of contagious, and should be washed constantly and sanitized with some disinfectant agent. Among the recommendations, the formulations based on ethyl alcohol and isopropyl alcohol are the most used, being the efficiency of these formulations based on the alcohol type, the concentration, the applied volume, and the contact time. The gel disinfectants are preferred by the population due to the facile and safer manipulation. However, due to the pandemic, the main gelling agent has become sparse and, in the function of this, some countries authorized the utilization of alternative formulations. The World Health Organization recommends two formulations, being one based on ethyl alcohol (80 Vol%) and the second on isopropyl alcohol (75 Vol%), destined for the local manufacture and with a fast and effective action.