Journal of the Brazilian Chemical Society This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.

Novel N-Heterocyclic Carbene Silver(I) Complexes: Synthesis, Structural Characterization, Antimicrobial and Cytotoxicity Potential Studies
In this study, a series of unsymmetrical N,N-disubstituted benzimidazolium salts were synthesized as N-heterocyclic carbene (NHC) (2a-2j) and their AgI complexes. Their structures were characterized by elemental analyses, 1H and 13C nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy techniques. Further, both the salts and their silver(I)-NHC complexes have been evaluated for their potential antibacterial properties against a panel of bacterial strains namely, Micrococcus luteus, Listeria monocytogenes, Salmonella Typhimurium, Staphylococcus aureus and Pseudomonas aeruginosa. The results show that silver comple...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Synthesis and Characterization of Hybrid Polymer Based on Functionalized Silica as Efficient Adsorbent for Heavy Metal Ions from Aqueous Solution
An organic-inorganic hybrid material based on a silica matrix and functionalized with imidazole group was successfully synthesized by the sol-gel process. The characterization techniques enabled the confirmation of the proposed structure as well as the effectiveness of the imidazole ring functionality in the structure of the material. It is insoluble in water and showed an anion exchange capacity of 2.944 mmol g-1, an excellent capacity for the adsorption of metal ions according to the literature. Thus, the metal halides CuCl2, CdCl2 and NiCl2 were adsorbed by the modified silsesquioxane from aqueous solutions. The adsorpt...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Corrosion Protection of Steel by Volatile Corrosion Inhibitors: Vapor Analysis by Gas-Diffusion Microextraction and Mass Loss and Electrochemical Impedance in NaCl Deliquescence Tests
A new methodology using gas-diffusion microextraction (GDME) was developed for the analysis of volatile corrosion inhibitors (VCIs). The evaluation of the inhibition efficiency and corrosion rate ( ν ) was performed by NaCl deliquescence tests and correlated with measurements of polarization resistance (Rp) obtained from electrochemical impedance spectroscopy (EIS) analysis and with the pH resulting from the atmosphere of the inhibitor (pHGDME). The correlation obtained between n and pHGDME indicates that the higher the value of pHGDME the lower the corrosion rate. The Raman spectra of steel was used to monitor in situ ad...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Absolute Configuration of (−)-Cubebin, a Classical Lignan with Pharmacological Potential, Defined by Means of Chiroptical Spectroscopy
This work describes the first determination of the absolute configuration (AC) of ( − )-cubebin by means of electronic circular dichroism (ECD), supported by quantum chemical calculations. The comparison of experimental ECD with the corresponding quantum chemical prediction for the proper diastereoisomer resulted in the definitive assignment of the AC of the naturally occurring ( − )-cubebin as (8R,8aR,9S). The challenging determination of the relative configuration (RC) of cubebin based only on experimental nuclear magnetic resonance (NMR) methods is stressed. Computation of the 13C and 1H NMR chemical shifts for all ...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Cocoa Agro-Industrial Residue (Theobroma cacao) as Inducer of the Production of Fungal Laccase and Kojic Acid for Application in the Biodegradation of 17-α-Ethinylestradiol
Due to the ability to catalyze the oxidation of several substrates, the enzyme laccase has been used in several applications, among them the bioremediation of emerging pollutants. This work evaluate the capacity of the cocoa agro-industrial residue to induce the production of Pycnoporus sanguineus laccase and to apply the enzymatic extract in the biodegradation of 17- α -ethinylestradiol (EE2). The macro and micronutrient levels of the cocoa residue were previously evaluated to establish correlations with induction of enzymatic production. The fungus was cultured for 7 days at 28 °C and shaking at 150 rpm. For the biodeg...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Temporal Evolution of Roughness Development on Polymer Surfaces Exposed to Non-Thermal Plasma
Processes such as ablation, erosion and corrosion generally create roughness patterns on solid surfaces. Despite the randomness of this phenomenon, some patterns can be described mathematically by studying statistically the mechanisms behind them. This paper reports an experimental study on the temporal evolution of the roughness development of polymer surfaces exposed to argon non-thermal plasma under reduced pressure of 5 mbar and 65 W of applied power. The substrates studied were polypropylene, high density polyethylene, polyamide-6 and poly(ether ether)ketone. The mean roughness data as well as the saturation roughness...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Quick Identification of the Time of Maturation of Artisanal Minas Cheese by FTIR-ATR Spectroscopy and Multivariate Techniques
The objective of this work is the identification of cheese maturation time using attenuated total reflection Fourier transform spectroscopy (FTIR-ATR) data and analytical measurements associated with chemometrics techniques. Minas artisanal cheeses were collected from 8 producers matured at times 1, 7, 14, 21, 28, 45 and 60 days, fractioned in rind and crumb for moisture, water activity (aw), dry in fat extract, pH, acidity, ashes, protein, extent and depth of proteolysis, color and identification of functional groups in FTIR-ATR. Principal component analysis (PCA), multiple linear regression (MLR) and partial least square...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

A Simple and Efficient Optimized Solid-Liquid Extraction with Low Temperature Partition Procedure for Dissipation and Translocation Study of Pesticide Residues in Rice Grains
This study evaluates the dissipation of bifenthrin and deltamethrin residues in unhulled rice and the translocation of these insecticide residues in husked rice stored at 25 °C in a biochemical oxygen demand (BOD) incubator for 35 days. For pesticide determination, the simple and efficient solid-liquid extraction methods with low temperature partition (SLE/LTP) followed by gas chromatography with electron capture detection (GC-ECD), for unhulled and husked rice were op timized and validated. These methods produced results of validated parameters consistent with Brazilian legislation, showing good efficiency (recovery rate...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Analysis of the Gene Expression and RNAi-Mediated Knockdown of Chitin Synthase from Leaf-Cutting Ant Atta sexdens
Chitin synthase (CHS) is the enzyme specifically associated with chitin synthesis, an important component of diverse organisms including insects. Two alternative spliced transcripts of the CHS gene (AsCHS-A1 and AsCHS-A2) were identified by quantitative reverse-transcription polymerase chain reaction (RT-qPCR) during the development of the leaf-cutting ant Atta sexdens. Expression profiles of AsCHS-A transcripts increased from larva to pupae and decay in workers. Phylogenetic analysis showed both transcripts are classified within class A insect CHSs. AsCHS-A1 showed the highest expression level in larvae and pupae, while A...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Kinetic Parameters of the Thermal Oxidation and Degradation Reactions in Soybean Oil and Palm Olein
This study aimed to determine the kinetic parameters for the thermal oxidation of these oils and of their residual used oils from the pre-frying industrial step on preparing breaded chicken meat. The main reactions were followed by thermogravimetry (TG) and differential scanning calorimetry (DSC); the formation of the produced substances was monitored by gas chromatography flame ionization detector (GC-FID) and Fourier transform infrared spectroscopy (FTIR). These analyses indicated different chemical pathways, according to the type of unsaturation and changes in the molecular structures of the fatty acids in the oils. Fro...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Action Items for Latin-American Chemists and Chemical Societies to Improve Equity and Diversity in Science
The chemists from Latin-America need to do more to achieve equality in the scientific world and gain greater recognition by the broader chemical community. For this, we should rethink our strategy to fight for a more inclusive science, not only internationally but also within our region. Raise your hands and take actions to support this movement. (Source: Journal of the Brazilian Chemical Society)
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Evaluation of Brazilian Monovarietal Extra Virgin Olive Oils Using Digital Images and Independent Component Analysis
Digital images associated with chemometric tools, in a non-destructive approach, have been applied for the evaluation of the Brazilian monovarietal extra virgin olive oil. Independent component analysis (ICA) was employed in the image data evaluation of olive oils produced from distinctive olive varieties, and it was successful in highlighting the natural grouping among the samples based on the color histograms (red, green and blue (RGB) channels). The study ’ s proposal indicates the ability of accurate separation of the twenty-four samples considering their color. To conclude and support the hypothesis, principal compo...
Source: Journal of the Brazilian Chemical Society - August 19, 2020 Category: Chemistry Source Type: research

Polyurethanes Obtained by Reacting 1,6-HDI with Monoglycerides from Babassu Oil: A DFT Study
This is a density functional theory (DFT)-based (M06) study on the polyurethane formation from 1,6-hexamethylenediisocyanate (1,6-HDI) reacting with the monoacylglycerol obtained from the babassu oil. As the lauric acid is the most abundant fatty acid in the vegetable oil, the 2-monolaurin was chosen to scrutinize the polyurethane formation. An analysis of two different mechanisms (stepwise and concerted) showed the concerted pathway as the most favorable, which involves the transference of the hydrogen in the 2-monolaurin to a nitrogen atom in the 1,6-HDI. Finally, the dimerization process takes place by coupling of ureth...
Source: Journal of the Brazilian Chemical Society - August 19, 2020 Category: Chemistry Source Type: research

Lignocellulosic Residues from the Brazilian Juice Processing Industry as Novel Sustainable Sources for Bioenergy Production: Preliminary Assessment Using Physicochemical Characteristics
This work aims to investigate the energy-related characteristics of apple bagasse, orange bagasse and cashew-apple bagasse to identify their potential as bioenergy feedstocks. For this, a detailed characterization was performed, including proximate analysis, ultimate analysis, atomic molar ratio, heating values, chemical composition, bulk density, bioenergy density, fuel-value-index (FVI), fossil fuel equivalence and potential CO2 retention. Proximate composition revealed moisture, volatile matter, fixed carbon and ash contents in the range of 7.8-9.3%, 67.1-74.2%, 16.2-22.0% and 1.6-5.7%, respectively. Typical values for ...
Source: Journal of the Brazilian Chemical Society - August 19, 2020 Category: Chemistry Source Type: research

Profiling the Cymbopogon nardus Ethanol Extract and Its Antifungal Potential against Candida Species with Different Patterns of Resistance
The essential oil of Cymbopogon nardus, citronella, has been extensively studied. However, the chemical and biological properties of the ethanolic extract (EE) of C. nardus have not been evaluated. The aim of this study was to characterize the chemical composition of the EE of C. nardus and its active fraction (FrD). Moreover, the cytotoxic and antifungal properties of these extracts against Candida species with different resistance profiles to conventional drugs were evaluated. The compounds identified in EE were mono-C- and di-C-glycosyl flavones and phenylpropanoid glycosides. Phenylpropanoid glycosides were identified ...
Source: Journal of the Brazilian Chemical Society - August 19, 2020 Category: Chemistry Source Type: research