Resumo em Inglês:

This study described the morphology, crystallinity, thermal and mechanical characterization of Polyamide 11 (PA11) porous film prepared by non-solvent induced phase separation (NIPS) method using formic acid (FA) as solvent. In addition, the miscibility of PA11/FA/H2O system was performed to generate a ternary phase diagram. The porous films morphology was investigated by Scanning Electronic Microscopy (SEM) analysis, the crystallinity by X-Ray Diffractometer (XRD) and thermal study by Differential Scanning Calorimetry (DSC). A cellulosic reinforcement was used in porous films and the stress-strain analysis was performance by Dynamic Mechanical Analysis (DMA). The porous films were prepared with polymer composition of 15, 20 and 25 wt%. The porous films showed different microstructure in function of polymer concentration. The 20 and 25 wt% porous films showed micropores structures with medium pores diameters between 0-10µm calculated by image analysis. The XRD analysis show predominance of α crystalline form of polymer at 20 and 25 wt% porous films. The degree of crystallinity increases with polymer concentration increase. The stress-strain analysis of porous films shows a proportional dependence of Young’s modulus with the increase of polymer concentration in each film.

Resumo em Inglês:

The phytochemical content of some Astragalus species distributed in Bulgarian flora has been previously studied. Among other compounds, flavoalkaloids, acylated flavonoids, flavonoid triglycosides and cycloartane saponins have been isolated so far. The composition of the rest of the representatives of this genus in Bulgaria is not explored yet. The aim of this study was to perform a screening for the presence of selected rare secondary metabolites (flavoalkaloids, acylated flavonoids, flavonoid triglycosides and cycloartane saponins) in selected Astragalus species. Samples were collected in different phenological stages and from different locations in the country. A novel and rapid ultra-high performance liquid chromatography – high resolution electrospray ionisation mass spectrometry (UHPLC-HRESIMS) method was developed and applied. For the first time a flavoalkaloid glycoside was determined from extracts of A. onobrychis var. chlorocarpus and A. glycyphylloides. From A. depressus an acylated derivative of kaempferol was newly identified. The flavonol triglycosides camelliaside A, alcesefoliside and mauritianin were proved in samples of A. glycyphylloides, A. onobrychis var. chlorocarpus and A. cicer for the first time as well.

Resumo em Inglês:

Natural deep eutectic solvents (NADES) based on xylitol, citric acid, and malic acid were synthesized and used in ultrasound-assisted extraction (UAE) and heating-bath extraction of phosphate rock and mineral supplement samples. Arsenic, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, P and Zn were determined by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP OES). The results showed the NADES as promising solvents for extraction of inorganic matrices compared to reference values and concentrations obtained using microwave-assisted acid digestion (MW-AD). Significant differences were observed for some elements, suggesting different chemical interactions between the synthesized NADES and each monitored element. For analytes extraction of phosphate rock, UAE presented the best results for As, Cr and P. Zinc was extracted with UAE and heating bath. Concerning mineral supplement, no significant differences were observed for Ca (UAE), Cd (UAE and heating bath), K (UAE and heating bath), Mn (UAE and heating bath), Na (UAE and heating bath), and P (UAE and heating bath). The NADES is a greener and a potentially alternative for the sample preparation compared to the official methods of analysis, can being used as selective extractor solvent in conventional sample preparation methods.

Resumo em Inglês:

Calea uniflora Less., commonly known in Brazil as “erva-de-lagarto” and “arnica-da-praia”, is used in folk medicine to treat internal and external bruises and as anti-inflammatory. However, despite the popular use there is a lack of information in terms of isolation and biological evaluation of its secondary metabolites. Thus, the aims of this study were to identify and characterize compounds of C. uniflora leaves with trypanocidal and leishmanicidal potential. METHODS: Structures of compounds were determined by HRESIMS spectra, and 1D and 2D NMR spectra. Then, they were tested for in vitro leishmanicidal and trypanocidal activities against Leishmania amazonensis and Trypanosoma cruzi intracellular amastigotes, respectively. RESULTS: Four germacranolide-type sesquiterpene lactones were isolated and characterized from dichloromethane fraction: 2α-hydroxy-8β-2’,3’,5’-trihydroxy-angeloyloxycostunolide (1), desacetyleupaserrin (2), 2α-hydroxy-8β-3’-hydroxy-2’,5’-epoxyangeloyloxycostunolide (3) and ovatifolin (4). All compounds are described herein for the first time for C. uniflora and Calea genus. Lactones 1, 2 and 4 demonstrated weak or no inhibition of the T. cruzi amastigotes, whereas compound 3 revealed a moderate effect (36.8%). Regarding the leishmanicidal activity, 4 exhibited a 59.9% inhibitory effect on the growth of L. amazonensis. CONCLUSION: None of the isolated compounds presented promising trypanocidal effect and 4 was the most active compound against L. amazonensis amastigotes.

Resumo em Inglês:

Copalic (CA) and kaurenoic (KA) acids are the main diterpenes found in the oleoresin extracted from the copaiba tree (Copaifera sp). This study aimed to characterize the metabolism of CA and KA in rat and human liver microsomes using liquid chromatography with tandem mass spectrometry (LC-MS/MS). The in vitro assays showed deviations from the Michaelian kinetics in the metabolism of CA and KA. Putative metabolites of CA and KA were characterized by LC-MS/MS using electrospray ionization (ESI) with time of flight (LC-ESI-TOF) and ion-trap (LC-ESI-IT) systems and identified as a CA isomer and 16,17-dihydroxy-kaurenoic acid, respectively. CA and KA are subject to extensive metabolism with each passage through the liver with extraction ratios (E) estimated as 0.97 and 0.99, respectively. In conclusion, the kinetic parameters and metabolites described here might support drug development and the traditional use.

Resumo em Inglês:

The genus Cryptostegia comprises two species, C. madagascariensis (Bojer) and C. grandiflora (Roxb. Ex R. Br) that belong to the Apocynaceae family and are widely distributed in the tropics, as in Australia, New Zealand, India and Brazil, where they cause great socioeconomic and environmental damage, as they are invaders causing damage, mainly in the cultivation of carnaúba, a native plant of great importance in the wax and derivatives industry in Northeast Brazil. Both are perennial shrubs, native to the island of Madagascar, have abundant latex and are known as rubber vine. The plants have the potential for pharmacological, biological and industrial applications. This is due to a rich source of chemical compounds (proteins, phenols, flavonoids, steroids, triterpenoids, cardiac glycosides, etc.) resulting from primary and secondary metabolism. The plants of the Cryptostegia genus showed many activities against bacteria, fungi, insects, Ae. aegypti larvae, Shistosoma sp., as well as for human health as analgesic, anti-inflammatory, antioxidant and antitumoral, and for industrial purposes acting as fibrinogenolytic, hydrolytic, anticorrosive, coagulant and depilatory for leather. Nevertheless, the toxicity is a limitation for the plant use then in order to stand out the economic potential a detailed research on toxicity and management of growing conditions is necessary.

Resumo em Inglês:

In recent years there has been an increasing interest in the development of nanomaterials with improved properties compared to their counterparts at the micro- and macroscopic scale. In this context, nanofibers obtained by electrospinning technique are highly attractive due to the unique combination of high surface area/volume ratio, porosity, flexibility, mechanical performance, simple processing and relatively low cost. In addition, the possibility to buildup nanofibers with different compositions, structures and properties allows the design of nanostructures for a wide range of applications. In this review, we will discuss the advances of the last decade in the use of the electrospinning to obtain nanofibers with different compositions and morphologies for varied applications. Specifically, we are interested in providing an overview of the state of the art in relation to the application of nanofibers in different areas, including healthcare, environment, sensing and energy. Finally, we will discuss the real perspective in terms of industrial application and future trends that have been pursued to improve the performance of electrospun nanofibers. This review will help researchers to understand the evolution and challenges of the area and will also stimulate even more interest in the development of new devices based on electrospun nanofibers.

Resumo em Inglês:

Cities urbanization and modernization increase emission sources, contributing to particulate matter (PM) composition heterogeneity and enhance the risk to human health and environment. This paper intends to survey the studies on particulate matter carried out in the state of Rio de Janeiro. The sampling of PM is generally made using Hi-Vol samplers to collect particles in fiberglass filter during 24 h every 6 days. Spectrometric techniques are used for elemental determination and ion chromatography for water-soluble species. The Environmental State Institute (INEA) is responsible for air quality monitoring in RJ. After 30 years, air quality standards have become more stringent and have included new pollutants. The highest PM concentrations were found in urban and industrial sites and the lowest in places away from urban activities or near the coast. Over the years, PM concentrations near steel complexes reduced even below the limits and varied at other places, remaining above the limits. Nitrate and sulfate were the main ionic compounds, and Fe, Al and Zn were the major elements in PM samples. It was also found Ni, V, Cd, Pb and Cu. Although air quality monitoring is efficient, it still needs to be improved to help reduce the environmental impact.

Resumo em Inglês:

In this paper, we show the development of a LabVIEW algorithm able to apply the delayed feedback control on oscillatory electrochemical reactions. The coupling of the control and the experiments was carried out by a real-time apparatus, measuring the faradaic current and, in sequence, applying a calculated circuit voltage as an analog output. The setup was used to control the oscillatory Cu/Sn electrodeposition dynamics, used as a model-system, and the results clearly demonstrate the control accuracy. Overall, the code may be a great tool for the controlled synthesis of nanomaterials in different oscillatory electrodeposition reactions, as it offers the ability to control the composition and structure of the deposit by fine tuning the dynamic properties.

Resumo em Inglês:

Nanoparticle (NP) applications have recently gained more space in the development of many products, especially in cosmetology. The aim of the present study was to validate a single particle inductively coupled plasma mass spectrometry technique for the detection and quantification of gold nanoparticles (AuNPs) and gold ions (Au (i)) in different cosmetics currently marketed in Brazil. The size limit of detection for pure AuNPs was 22 nm, and a concentration limit of detection of 2.3×106 particles g−1 was achieved. The limit of detection for total gold was 0.02 μg L−1 obtained in standard mode conditions. The recovery achieved was 98% for dissolved Au and 109% for AuNPs; the relative standard deviation was <5%. This validated method was applied to cosmetic products (n = 10) from different national and international industrial producers. Most cosmetics analysed contained quantifiable amounts of dissolved gold (< 0.005-2.1 μg g−1) and only four contained quantifiable amounts AuNPs the variability of the results detected (< LOD – 9.3 × 108 particles g−1). The products that contained the greatest amount of these metallic NPs were the artisanal products. The results demonstrate the importance of adequate quality control for cosmetics to ensure consumer safety.

Resumo em Inglês:

The present work discusses some of the difficulties that chemistry undergraduates have with electrochemistry and possible impacts on higher education. They responded to a questionnaire about their insights and experiences regarding electrochemistry teaching, as well as their knowledge about it. The responses were categorized according to their difficulties, mistakes, and alternative views, by means of content analysis. The data revealed that undergraduates often enter the course without solid previous knowledge about redox phenomena, since few of them managed to develop more elaborate and correct responses, directly impacting the continuity of electrochemical studies in higher education.

Resumo em Inglês:

This research investigates difficulties associated to the curricular component Organic Chemistry I based on a study case of Chemistry undergraduate courses (Bachelor and Teachers education) in two Federal Universities in the Brazilian South region. The analytical process integrated official documents of the courses (pedagogic projects, students’ grades), questionnaires, interviews, and researcher’s logbook of classes. Results show that the students’ success in Organic Chemistry I is lower than the sum of failure, unattendance, and temporary cancellation rates altogether in the curricular component offered by the different teachers and institutions studied. A complex scenario is highlighted in relation to factors that affect learning and teaching processes in undergraduate Organic Chemistry courses. The subjects’ responses highlight difficulties related to specific contents, such as conformation and spatial visualization of molecules, stereochemistry, and reaction mechanisms; lack of concepts from High School; and individual habits and characteristics of teachers, students, or both, such as didactics, concentration, and engagement. The results report on the importance of rethinking strategies and methodologies in the context of Organic Chemistry I in Higher Education.

Resumo em Inglês:

Buffers are a widely used resource to keep solutions from abruptly change their pH when amounts of acids or bases are added or when dilution occurs. Considering this, buffer is a topic addressed in several university majors and due its relevance should be well known by students and by all professionals who eventually need to prepared a buffer. Mistakes during the procedure might bring unwanted effects depending on the purpose of the buffer. Even though the theory behind buffers is extensively covered in textbooks, the calculations required can sometimes be interpreted as difficult. Therefore, the aim of this work is to disseminate a tool to assist on these calculations. We provide a practical guide on how to prepare buffers of the user’s choice with or without ionic strength adjustment. Exploring the free software PeakMaster®, the user can calculate pH, ionic strength, buffer capacity and predict the precise concentration of each component involved to the proper preparation of the most common and several others buffer solutions. In addition, we hope this paper can be helpful for anyone who is interested in acquire deeper knowledge about buffers.

Resumo em Inglês:

Quality is an increasingly present concept nowadays, so meeting the customers’ needs, who buy and use products and hire services, becomes essential. For laboratories, the concept is applied to the reliability and traceability of the results produced and presents itself not only to meet the customer’s needs, but also to allow the signing of agreements in the international trade. The concept of Quality in a laboratory can be carried out from the elaboration of a Quality Management System (QMS). To this end, the normative document ISO/IEC 17025, internationally accepted, has been changing over the years aimed at instructing the elaboration of a management system which proves the technical capacity of testing and calibration laboratories and guides the generation of reliable results. The document is in its third version as a standard, the most current one published in 2017, and it presents requirements to achieve the proposed objective and the quality assurance. In the face of the importance of these concepts and the unquestionable need of laboratories to provide reliable and traceable results, this article presents the norm history and its most recent changes. Its intent is support laboratories whose objective is to implement a QMS according to this normative reference.