Resumo em :

The benzophenones are synthetic and natural compounds presenting a variety of activities, including photoprotective, cytotoxic and antiviral. It is herein described the preparation of a series of twenty-seven benzophenone derivatives bearing 1,2,3-triazole functionalities and the evaluation of their photoprotective, cytotoxic and antiviral on Zika Virus (ZIKV) activities. The compounds were prepared in three steps, namely reduction of benzophenone, alkylation of diphenylmethanol and CuAAC reactions. The in vitro evaluation of the photoprotective activity revealed that the most active derivative 4-((benzhydryloxy)methyl)-1-(4-nitrobenzyl)-1H-1,2,3-triazole (4k) displayed UVB sun protection factor equal to 6,9±0,53, which make this compound a possible candidate to be used in formulations for photoprotective applications. In terms of cytotoxicity, the compounds were evaluated against MDA-MB-231 and B16F10 cell lines. It was observed that the compounds were more active against MDA-MB-231 cells and three of them were capable of reducing cell viability by approximately 55% at 100 µmol L-1. In the antiviral screening against ZIKV, compound 4-(3-benzhydryloxy)propyl)-1-(3-methylbenzyl)-1H-1,2,3-triazole (5j) was the most effective in mantaining Vero cell viability.

Resumo em Inglês:

The upscaling of Xylaria cubensis, an endophyte of Eugenia brasiliensis (Myrtaceae), in PDB medium led to the isolation of known compounds including cytochalasin D (7) and cytochalasin C (8), which exhibited relatively higher phytotoxic activity in all the concentrations tested compared to the commercial herbicide GOAL®. Besides the aforementioned metabolites, one diketopiperazine (DKP) and two isocoumarins were isolated and two DKPs were also identified in the mixture. The structures were determined by 1D and 2D 1H NMR, MS analyses and were compared with the literature.

Resumo em :

Lots of Educational Institutions hold their own geocollection due to its utility and versatileness in the practical formation of new generations of skillful professionals in many areas of Science and Technology. The Geoscience laboratory of the Federal University of São Carlos has a collection of minerals used in engineering, mineralogy and other technological courses ministered to undergraduates of different programs. Three samples of this collection were identified using Raman spectroscopy. The analysis carried out in this work enabled the characterization of the major mineral components in the samples as well as the identification of other minor crystalline phases present in the sample. It is important to notice that this information could not be obtained using the regular analyses of mineral properties, such as density, streak, hardness, brightness, cleavage, among others. As a result, the samples A170801 and A170802 were characterized as being mainly calcite (CaCO3) and spodumene (LiAlSi2O6), respectively. On the other hand, sample A170803 show the presence of three different minerals: graphite (C), quartz (SiO2) and muscovite [KAl2(Si3Al)O10(OH,F)2].

Resumo em Inglês:

The cobalt nanoparticles (NPs-Co) were synthesized and applied in the removal of Cr(VI). The obtained nanomaterials presented magnetic properties and were characterized by the techniques of Transmission Electron Microscopy and X-ray diffraction. The NPs-Co, with a diameter of less than 50 nm, had a composition based on metallic cobalt and cobalt oxide. The NPs-Co were applied in the removal of Cr(VI) being evaluated different parameters such as time of equilibrium, initial pH, dose of NPs-Co, concentration of Cr(VI), and system temperature. The removal of Cr(VI) was favored at lower pH values, being about 100% at pH 2.0. With the increase of Cr(VI) concentration from 40.0 to 300.0 mg L-1 the removal decreased from 80 to 15%. The NPs-Co dose promoted an increase in removal reaching 90% at a dose of 1.0 g L-1. The removal process was spontaneous and endothermic, and the Langmuir isotherm model fit better to experimental data. The maximum removal capacity was approximately 70.0 mg g-1. The removal kinetics followed the pseudo-second order model. The mechanism of Cr(VI) removal occurred through adsorption by electrostatic interactions between CrO42- anion and Co-NPs, followed by reduction of Cr(VI) to Cr(III) and, lastly, co-precipitation of Cr(III) as Cr(OH)3 on the NPs-Co.

Resumo em Inglês:

This article reports the synthesis of two zinc(II) complexes containing phenoxy-imine ligands and their application as initiators of bulk ring opening polymerization (ROP) of L-lactide (LLA). The phenoxy-imine ligands (L1 and L2) were obtained by condensation reactions of salicylaldehyde derivatives with 2,6-diisopropylaniline. The reactions of L1 and L2 with ZnEt2 in the presence of n-BuOH afforded [Zn(L1)(OBu)] (C1) and [Zn(L2)(OBu)] (C2), which were characterized by elemental analysis, FTIR and 1H NMR spectroscopy. In addition, the geometries of both complexes were investigated by DFT (B3LYP/LACV3P**) calculations. C1 and C2 were tested as initiators of ROP of LLA at 180 °C using different LLA/Zn molar ratios, namely 500, 1000 and 2500. Both complexes showed good activity, resulting in conversions up to 90-92% in 2 h. The poly(L-lactide) obtained displayed Mn ranging from 40.000-109.000, relatively low polydispersity (Mw/Mn = 1.2-2.1) and high stereoregularity with Tm = 176 °C.

Resumo em Inglês:

A new silicon-aluminum-zirconium ternary oxide (SiO2/Al2O3/ZrO2) was prepared by the sol-gel method followed by one-step washing with absolute ethanol or two-step washing with absolute ethanol followed by ultra-pure water. Both ternary oxides presented high surface area (over 340 m2 g-1). The binding energy values for Zr3d and Al2p levels showed the insertion of Zr and Al atoms in silica matrix, confirming the dispersion surface of these elements as shown by scanning electron microscope (SEM) and energy dispersive X-ray fluorescence spectroscopy (EDXRF) data. A weight loss around 40 wt.% was found for both samples submitted to thermogravimetric analysis (TGA). Crystallographic data showed the presence of monoclinic and tetragonal ZrO2 phases in different proportions according to the calcination temperature. Regarding the acid-base properties, temperature-programmed desorption of CO2 (CO2-TPD) profiles suggested that washing with water reduced the overall basicity of the samples and removed the strongest basic sites. However, according to temperature-programmed desorption of NH3 (NH3-TPD) profiles, washing significantly increased the amount of weak acid sites, in agreement with pyridine adsorption data. Brønsted acid sites (BAS) are ever dominant but washing with ethanol followed by water reduced the number of Lewis acid sites (LAS).

Resumo em Inglês:

This paper reports a new and validated capillary electrophoresis method to determine Roflumilast (RFL) with an internal standard in tablet. The separation was made on an uncoated fused-silica capillary column 50 cm effective length and 75 µm i.d. 20 mmol L-1 of Na2B4O7 buffer including 15% (v/v) methanol (pH=9.5) was used as background electrolyte. A potential of 20 kV was applied. The developed method was linear in the range of 0.75 µg mL-1 and 15.0 µg mL-1. LOQ and LOD values were 0.074 µg mL-1 and 0.022 µg mL-1 for inter-day, respectively. The precision value was 0.78% for inter-day. The accuracy was between 98.63 and 100.97 as recovery. This study was the first report for the determination of RFL in Daxas® solid dosage form using CE. The validated method was found as rapid, cheap, easy to apply and uses small sample volume, very little organic solvent, and high efficiency and resolution.

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This review attempts to present a broad view of the technique laser-induced breakdown spectroscopy (LIBS), since its origin, fundamentals, sample preparation strategies, use of chemometric tools for data processing, the advantages and limitations with regard to qualitative and quantitative analysis, aplications and future trends as an analytical technique that is in consolidation in analytical chemistry. LIBS is a rapid and versatile, which is able of providing qualitative and quantitative analytical information for practically any sample, in a virtually non-destructive way, without any substantial sample preparation. The instrumentation is simple, robust, compact, and enables remote analysis. The advancement of the LIBS applications in the areas of agriculture, environmental, food, biological/pharmaceutical, forensic, metallurgy and electronic waste were discussed in detail in this review. We consider that this review will be an important tool concerning dissemination of the LIBS, mainly for audience of undergraduate courses, and disciplines related to instrumental analysis.

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Over the past few years, metabolomics has been employed in a broad range of applications in different research fields. Microbial metabolomics has been applied in several microbiological areas, such as identification of microorganisms, cell mutations, functional gene approach, identification of unique metabolic pathways and microbial engineering, leading to a better understanding of the global metabolism and metabolic regulation of certain systems. Metabolites produced by microorganisms constitute a large promising group with diverse applications; however, most of these systems are still unknown and underexplored. In this context, the overall analysis of metabolites involved in a biological system can be used to discover potential biomarkers or specific metabolic changes due to a biological phenomenon studied. In this sense, this review aims to understand the main challenges faced by each step of the workflow in the metabolic analysis of microorganisms and how these difficulties have been overcome. A critical analysis of the articles published within the last five years will be accomplished in this paper to understand how these studies have contributed to the microbial metabolomics research. Moreover, major trends observed in this area will be highlighted here in order to guide readers interested in microbial metabolomics in their future researches.

Resumo em :

We have recently made studies of electrodeposits of Co onto graphene attached to different substrates, successfully performed via in-situ magnetization measurements. The magnetic analysis of deposits as a function of time lapse, indicate that Co grows with different magnetic characteristics from the beginning to the end of each run, independent of the substrate over which the graphene has been deposited on. In this technical note, we use these results and some obtained in several previous researches developed in our laboratory during the last 20 years, to show that the association of in-situ magnetometry with electrodeposition processes can be a powerful tool to understand the dynamics of the electrochemistry involved, as well as the physics of the magnetic materials fabricated. The Electrochemical Alternating Gradient Force Magnetometer (EC-AGFM) is appropriate for: (i) studying the magnetic properties of the electrodeposits either during deposition or dissolution; (ii) evaluating the electrodeposition dynamics via the sample’s magnetic response; (iii) scrutiny of the electrodeposits as they undergo chemical changes (oxidation, etc.); (iv) studying the deposited materials from the atomic level up to bulk; v) studying the effects of addition of trace amounts of anions in the solution and their impact on the magnetic properties of metal adatoms.

Resumo em Inglês:

Charcoal has a large share in the Brazilian market. The production is carried out by pyrolysis of biomass at different temperatures, between 300 and 500 °C. In this study, the corn cob pyrolysis was investigated using thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Samples after pyrolysis were compared with raw biomass to evaluate changes in fuel characteristics. In DTG curves a reduction in the number of degradation peaks in the carbonized material was observed. The FTIR spectra allowed to identify the aromatic ring of the lignin in the charcoals structure, indicating the presence of this compound even in charcoals produced with a temperature of 500 °C. It can be concluded that the temperature of 400 °C was enough to completely degrade the hemicellulose and cellulose of the biomass, resulting the final product (charcoal) less reactive or thermally more resistant than the in natura corn cob.

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This paper presents the results of a participant research. We represent the science class-room as conditioned by the heterogeneity of the identities constituting it from positions that are defined and legitimized by our social structure. We present a pedagogical intervention (PI) entitled “Traditional knowledge of African-matrix peoples and communities”. The PI was audio and video recorded and analyzed using Discourse Analysis. Our results show that the religiosity of Brazilian African-matrix is nowadays a resignification of the cults of various ethnic groups in the African continent, in this sense, the plants and leaves were incorporated to people’s everyday life. Plants perform a sacral role of symbolic value and a functional role through its chemical components. We understand scientific knowledge is not traditional knowledge, but it relates to it. Our results show how it is possible to bring these topics to the Chemistry class-room. To establish a dialogue among these various forms of interacting with the world is necessary to break up with the epistemicide reaching our classrooms.

Resumo em :

In the year 2019 the periodic table of the elements will celebrate 150 years. A frequent misunderstanding says that palladium might have been initially discovered in samples from Brazil. Indeed it was found in the country in the early nineteenth century, but this discovery was preceded by other findings elsewhere in South America. This article will report its discovery, both abroad and in Brazil, as well as many other related aspects.