Resumo em Inglês:

In this study, it is reported the fractal dimension and morphology of ultrafine particles emitted by a diesel engine run with B4, B50, and B100. Transmission electron micrographs evidenced two main groups of particles with characteristic and distinct morphological behaviors: (i) particle agglomerate structures self-organized within a fractal-like geometry, and (ii) amorphous and irregular particles with diffuse edges in a liquid-like particle appearance, mainly associated with some sub-fractions of samples collected from B50 and B100 combustion. Particles from (i) showed typical diesel soot morphology and fractal dimension. Primary particle diameter (Dpp) was 24 ± 4 nm, 23 ± 4 nm, and 20 ± 4 nm for B4, B50, and B100, respectively. Mean aggregate gyration diameters (Dg) ranged from 242 ± 140 nm for B4, 210 ± 135 nm for B50, and to 232 ± 140 nm for B100. In turn, fractal dimensions (Df) were 1.94, 1.89, and 1.99 for B4, B50, and B100, respectively. On the other hand, particle from (ii) had their morphology impaired from the addition of biodiesel to petrodiesel in a way it did not follow a fractal geometry.

Resumo em Inglês:

This work presented the first study of organocatalytic behaviors of inherently chiral calix[4]arenes substituted at the lower rim. A pair of N, O-type enantiomers based on inherently chiral calix[4]arenes substituted at the lower rim were readily synthesized and applied to catalyze Henry reaction between aromatic aldehydes and nitromethane. Their organocatalytic reaction can afford the desired products in excellent yields (up to 99%) but poor enantioselectivities (up to 7.5% ee).

Resumo em Inglês:

Phytochemical investigation from carnauba (Copernicia prunifera) wax led to the identification of sixteen dammarane-type triterpenes, including thirteen new characterized as: (24R*)-methyldammara-20,25-dien-3α-ol and a mixture of alkyl (24R*)-methyldammar-25-en-20-ol-3β-carboxylates, together with three previously described triterpenes: carnaubadiol, (24R*)-methyldammara-20,25-dien-3β-ol and (24R*)-24-methyldammara-20,25-dien-3-one. Moreover, four fatty alcohols (eicosanol, docosanol, tetracosanol and hexacosanol) as well as four sterols (cholesterol, campesterol, stigmasterol, and sitosterol) were also obtained. These compounds were isolated using classical chromatographic methods and their structures were determined by spectroscopic and chemical methods.

Resumo em Inglês:

Copaiba oil, an oleoresin extracted from Copaifera genus, has been widely used in popular medicine for the treatment of several diseases. The aim of this study was to investigate the antifungal activity of the copaiba oil and its isolated compounds caryophyllene oxide, copalic acid and acetoxycopalic acid against Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum gypseum strains, using microdilution method and microscopy techniques. It was found that the copaiba oil and the copalic acid were active against dermatophytes by minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) tests. The MIC and MFC of copaiba oil against T. rubrum, T. mentagrophytes and M. gypseum were 125 µg mL-1 (250 µg mL-1), 500 µg mL-1 (500 µg mL-1) and 250 µg mL-1 (250 µg mL-1), respectively. For copalic acid, the MIC and MFC were 50 µg mL-1 (100 µg mL-1), 100 µg mL-1 (100 µg mL-1) and 50 µg mL-1 (100 µg mL-1), respectively. Fluorescence microscopy and scanning electronic microscopy were used to investigate inhibition on hyphal growth by compounds, copaiba oil and copalic acid, showing a strong inhibition and an irregular growth pattern. Cell wall, cytoplasmic membrane and intracellular contents were also damaged. In conclusion, copaiba oil and copalic acid showed great activity against dermatophytes, being potential compounds for the development of antifungal drugs.

Resumo em Inglês:

In this work the presence of soot in laminar diffusion of diesel and blends diesel/biodiesel flames were investigated in the following proportions: 5, 10, 20 and 50% of biodiesel. The technique of laser-induced incandescence (LII) was used for the soot detection. Horizontal mapping were performed at two heights (80 and 260 mm above the burner) to investigate the distribution of soot along the studied flames. The experiment was performed with a pulsed Nd:YAG laser with the wavelength of 1064 nm. The results have shown that the soot emission decreases as the amount of biodiesel increases in the blends.

Resumo em Inglês:

The screening for antimicrobial activity of twenty five endophytic fungi isolated from the aerial parts of Paepalanthus chiquitensis (Eriocaulaceae) was assayed against the bacteria Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli and Salmonella setubal, and the yeast fluconazole-resistant Candida albicans. The ethyl acetate extract produced by Fusarium fujikuroi was the most bioactive and this fungus was chosen for the chemical study, affording the isolation of an alkaloid 2-(4-butylpicolinamide) acetic acid and three known metabolites: fusaric acid, indole acetic acid and the sesterterpene terpestacin. The minimal inhibitory concentration of the extract and of fusaric acid and indole acetic acid for all the tested microorganisms had values from 125 to 1000 µg mL-1.

Resumo em Inglês:

This work describes the preparation, characterization and properties study of multifunctional nanocomposites between poly(styrene-co -butyl acrylate) latex and different carbon nanostructures: iron-filled carbon nanotubes (CNT), graphene or graphene oxide. Different approaches were employed to prepare stable aqueous dispersions of these nanostructures, according to the specificity of each nanomaterial. The nanocomposites were characterized by Raman and Fourier transform infrared (FTIR) spectroscopy, as well as by scanning probe microscopy (SPM) at different modes, providing information regarding the nature of the interaction between the carbon nanostructures and the polymeric matrix. The synergistic effect between the components results in improved mechanical, electrical, thermal and chemical properties of the nanocomposites, when compared to the neat polymer. In addition, the iron species into CNT cavities provide an interesting and unusual magnetic property of the nanocomposites. Results show that the properties of the nanocomposites can be modulated aiming desired application by simply selecting the amount and/or the kind of carbon nanostructure. This work provides information on the features of the three systems used, showing the range of properties that can be covered by using the three nano-fillers.

Resumo em Inglês:

Ruthenium benzylidene complexes were evaluated as catalysts in atom-transfer radical polymerization (ATRP) of methyl methacrylate (MMA) under different reaction conditions. The mechanism by which Grubbs 1st and 2nd generation catalysts mediate olefin metathesis has been studied, little is known regarding the mechanism of ATRP reaction promoted by these complexes. Conversion and semilogarithmic kinetic plots as a function of time were correlated to the different catalysts and reaction conditions; especially in the presence of Al(OiPr)3 as additive. Molecular weight (Mn) and polydispersity index (PDI) values changed with different catalysts in the presence or absence of Al(OiPr)3. Kinetic studies by 1H NMR revealed that two complexes in the presence of Al(OiPr)3 are converted into ATRP-active with the dissociation of PCy3, but with the benzylidene group preserved. More controlled polymerizations were achieved using Grubbs 1st and, the presence of Al(OiPr)3 improved the control levels for both catalysts.

Resumo em Inglês:

New ruthenium(II) complexes with formulae [RuCl(CO)(PPh3)2L1] and [RuCl(CO)(PPh3)2L2] (L1 = S-allyl-4-methoxy benzylidene hydrazine carbodithioate, L2 = S-allyl-1-naphthylidene hydrazine carbodithioate) have been synthesized and characterized by elemental analysis, Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), UV-Vis, electrospray ionization (ESI)-mass spectral studies. Both the Schiff base ligands are coordinated to ruthenium through azomethine nitrogen (C=N) and thiolato sulfur donor atoms in the thiolate form. On the basis of spectral data obtained, an octahedral structure has been assigned to all the new complexes, satisfied by coordination of donor atoms N and S. The stability of complexes in solution was determined by molar conductivity measurements. The interaction of the two complexes with calf thymus (CT) DNA was investigated by fluorescence spectroscopic and viscometric methods. Bovine serum albumin (BSA) protein was examined by fluorescence spectroscopic methods. These techniques indicate that the two metal complexes bind to DNA via intercalation mode and BSA bind with static interaction. Catecholase and phosphatase like activities promoted by these two complexes under physiological conditions have been studied. In vitro anticancer activities have been demonstrated by 3,4,5-dimethylthiazolyl-2-2,5-diphenyltetrazolium bromide (MTT) assay, acridine orange/ethidium bromide (AO/EB) and diamidino-2-phenylindole (DAPI) staining against HeLa cancer cell line.

Resumo em Inglês:

We carried out the physico-chemical characterization of Immobead 150, a hydrophobic support for the immobilization of lipases. Thermomyces lanuginosus lipase (TLL) was immobilized on Immobead 150 by multipoint covalent attachment (ImmTLL) and the morphological, textural, structural, thermal, and physico-chemical properties of the support, before and after enzyme immobilization, were investigated. Immobead 150 presents approximately 1,000 µmol of epoxy groups per gram of support, a high hydrophobicity, and good thermal stability. The spherical particles of Immobead 150 present average diameters of 155 µm, specific surface areas of 137 m2 g-1 and pore volumes of 0.37 cm3 g-1, showing pores in the region of the micro and meso sizes. The immobilization process of TLL (150 mg g-1) caused a decrease of the specific area and pore volumes, to 63 m2 g-1 and 0.25 cm3 g-1, respectively, as a result of coating of the support surface by the enzyme molecule. However, the immobilization process did not affect the morphology of the support. The obtained biocatalyst was effective for the syntheses of fatty acid ethyl esters (biodiesel), and of aroma esters, showing yields of 68 and 70%, respectively, similar to commercial preparations used as controls.

Resumo em Inglês:

The complex [Ti3(O)(Cl)(ONep)9] and two iron(II)-containing products, [Fe4Cl8(thf)6] and [Fe2Cl3(thf)6][FeCl4], were synthesized by a redox reaction involving [Ti3(OiPr)11][FeCl4] and neopentanol; the structures of compounds [Ti3(O)(Cl)(ONep)9] and [Fe2Cl3(thf)6][FeCl4] have been confirmed by X-ray diffraction methods. Variable-temperature 1H NMR analysis of [Ti3(O)(Cl)(ONep)9] revealed signals for three non-equivalent neopentoxides in the 1:1:1 integration ratio, indicating the maintenance of the trinuclear structure in solution. Alkoxide [Ti3(O)(Cl)(ONep)9] was employed as initiator in both bulk and solution polymerization of ε-caprolactone (ε-CL) at various temperatures, monomer/initiator molar ratios and reaction times. [Ti3(O)(Cl)(ONep)9] produced poly(ε-caprolactone) in high yields, with molecular weights ranging from 7100 to 9800 g mol-1 and PDI (polydispersity index) values between 1.3 to 1.5. The reactivity of [Ti3(O)(Cl)(ONep)9] in the ring-opening polymerization (ROP) of ε-CL was compared to those of [Ti3(OiPr)11][FeCl4] and [Ti(OiPr)4]. The better polymerization reactivity shown by [Ti3(O)(Cl)(ONep)9] seems to be associated with structural features, as well as with the stronger Lewis basicity of -ONep over -OiPr ligands and the maintenance of the trimetallic structure in the reaction media.

Resumo em Inglês:

A sensitive high-performance liquid chromatography-fluorescence detection method (HPLC-FLD) was developed and validated for 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) determination in wastewater samples. Sample preparation was performed by solid-phase extraction (SPE) on Hypersep C18 cartridges. Conditioning and elution solvents and sample volume were investigated by a 23 factorial design for both analytes. The pre-concentration factor was 2500 times, allowing to quantify 5.0 ng L-1 for both hormones. The SPE-HPLC-FLD method was successfully applied to detect and quantify trace amount of target compounds in raw and treated wastewater samples. E2 was found below limit of quantification in influent and effluent samples. Nevertheless, the recoveries of E2 in standard addition experiments were between 41 and 72%, with relative standard deviations between 4 and 16%. An important matrix effect was observed in the determination of EE2, with fluorescence signal suppression.

Resumo em Inglês:

Jatropha curcas L. is an oil crop that has been studied as a potential source of biodiesel. A high protein pie is produced as a byproduct of the biodiesel production, which could be used as animal feed. However, the pie has toxic compounds, as phorbol esters and other toxins, which prevents the use as animal feed. For this reason, Embrapa (Brazilian Agricultural Research Corporation) has been working in genetic breeding to develop non-toxic J. curcas genotypes. To evaluate this process, a simple and fast analytical technique was employed to obtain responses in a short time. Leaf spray (LS) is a recent ambient ionization mass spectrometry technique in which the sample itself serves as support and ion source. Here, toxic and non-toxic J. curcas leaves were differentiated by LS using a linear ion trap mass spectrometer and partial least squares discriminant analysis (PLS-DA) model chemometrics. It was possible to differentiate toxic and non-toxic leaves and to identify the m/z values that contribute to discrimination between the groups.

Resumo em Inglês:

Three new dibenzoylmethane derivatives, (E)-3,4-methylenedioxy-2'-methoxy-2'',2''-dimethylpyrano-(5'',6'':3',4')-7-methoxychalcone, 2'-hydroxy-5'(3'''',3''''-dimethylallyl)-8-(α,α-dimethylallyl)-furano-(4'',5'':3'4')-dibenzoylmethane and 2'-O-(3'',3''-dimethylallyl)-8-(α,α-dimethylallyl)-furano-(4'',5'':3'4')-dibenzoylmethane, were isolated from a dichloromethane extract from the root bark of Muellera filipes (Benth.) M.J. Silva & A.M.G. Azevedo, along with two dibenzoylmethane derivatives, 2'-methoxy-8-(α,α-dimethylallyl)-furano-(4'',5'':3',4')-dibenzoylmethane and 2'-hydroxy-8-(α,α-dimethylallyl)-2",2"-dimethylpyrano-(5",6":3',4')-dibenzoylmethane; one flavanone, isolonchocarpin and one flavone, pongaglabrone, which had been previously isolated from other sources. The molecular structures of the new dibenzoylmethane derivatives were determined by analysis of their spectral data (1H and 13C nuclear magnetic resonance (NMR), 2D-NMR, NOE (nuclear Overhauser effect) and HRMS (high resolution mass spectrometry). The known compounds were identified using 1D experiments and comparison with spectral data from the literature. 2'-O-(3'',3''-Dimethylallyl)-8-(α,α-dimethylallyl)-furano-(4'',5'':3'4')-dibenzoylmethane displayed strong activity against the human cancer cell line OVCAR-3 (ovarian), and 2'-methoxy-8-(α,α-dimethylallyl)-furano-(4'',5'':3',4')-dibenzoylmethane showed high selectivity for cell lines NCI-H460 (lung) and UACC-62 (melanoma).

Resumo em Inglês:

Bisphenol A (BPA) is an industrial material which can lead to endocrine disorders. In this work, a simple and sensitive spectrophotometric method for determination of BPA using diazotization-coupling reaction was presented. To achieve the best performance of the developed method, the experimental parameters were optimized in terms of reagent concentration, reaction time, pH, and temperature. Under the optimal conditions, the absorbance increased linearly with the increasing concentration of BPA in the range of 0.16-10.4 µg mL-1 with the correlation coefficient of 0.9991 and the detection limit of 0.05 µg mL-1. Results achieved with the spectrophotometric method were compared with those obtained using high performance liquid chromatography (HPLC) method. The proposed method was successfully applied to determine BPA in milk and water bottle samples and satisfactory results were obtained, which make it very suitable for routine analysis of BPA in quality control laboratories.

Resumo em Inglês:

In this series of papers, AC induced corrosion of steel pipe under cathodic protection was investigated. In this Part III, the most realistic model was devised, i.e., the cathodic current was composed of the reductions of dissolved oxygen partly controlled by diffusion and of the water following the Tafel law. The cathodic protection potential necessary to mitigate the corrosion for various AC amplitudes were evaluated. In this modeling approach, no change of soil properties due to AC corrosion is considered. Mean DC values of corrosion potential shift and the corrosion current density in presence of AC signal were calculated in reduced scale making possible field applications by introducing an appropriate set of corrosion kinetics parameter collected without AC signal. In a highly corrosive soil, the reduction of dissolved oxygen is slow compared with that of the water reduction, and then the corrosion behavior becomes similar to the case examined in Part II.

Resumo em Inglês:

The aim of this study was to develop and characterize poly-ε-caprolactone (PCL) and poly(D,L-lactic-co-glycolic)-acid (PLGA) microparticles containing coencapsulated trans-dehydrocrotonin (t-DCTN) and t-DCTN:hydroxypropyl-β-cyclodextrin inclusion complex (t-DCTN:HP-β-CD), with t-DCTN loaded at concentrations ranging from 11.25 to 45.00 mg. A preformulation study was carried out using a 24-1 fractional factorial design. Microparticles were prepared using the double w/o/w emulsion-solvent evaporation method. The coencapsulated t-DCTN:HP-β-CD-loaded PLGA microparticles (t-DCTN/t-DCTN:HP-β-CD/PLGA-MPs) presented a smaller particle size (9.6 ± 0.1 µm) and higher drug loading (13.93 ± 0.05%, corresponding to 90.1 ± 0.3% of encapsulation efficiency, EE) and t-DCTN-loaded PLGA microparticles (t-DCTN/PLGA-MPs) presented particle size of 37.0 ± 0.2 µm and drug loading of 10.12 ± 0.01% (EE of 71.2 ± 0.1%). The coencapsulation of t-DCTN and t-DCTN:HP-β-CD into PLGA microparticles increased drug loading (50%) and improved the drug controlled release (k2 = 0.0475 and De = 0.0475 × 10-11 cm2 s-1). Taking into account these findings, new oral formulation of PLGA microparticles containing coencapsulated t-DCTN and t-DCTN:HP-β-CD are available as biocompatible drug delivery systems for further pharmacological purposes.

Resumo em Inglês:

The building of partial least squares (PLS) regression models using near infrared (NIR) and ultraviolet (UV) spectroscopies to estimate the concentrations of phorbol esters (PEs) in Jatropha curcas L. is presented. The models were built using two algorithms for variable selection, ordered predictors selection (OPS) and genetic algorithm (GA). Chromatographic analyses were performed to determine the concentrations of PEs. Spectral data were obtained from seeds and oil extract. The results of PLS models were performed by analyzing statistical parameters of quality such as root mean square error of prediction (RMSEP) and correlation coefficient of external predictions (Rp). The parameters obtained for NIR-PLS and UV-PLS models with OPS were respectively: RMSEP 0.48 and 0.22 mg g-1 and Rp 0.49 and 0.96. For GA were obtained, respectively: RMSEP 0.52 and 0.28 mg g-1 and Rp 0.12 and 0.95. The models built from seeds and oil extracts can be used respectively for screening and to accurately predict the PEs content. The OPS method provided simpler and more predictive models compared to those obtained by the selection of variables using the GA. Thus, the UV-PLS-OPS model can be used as an alternative method to quantification of PEs.

Resumo em Inglês:

8-Methoxypsoralen is a widely sold drug in Brazil as handled capsules and creams because it is only industrially available as soft gel capsules of 10 mg. In order to contribute to the quality control of these pharmaceutical forms, a spectrofluorimetric method was implemented and applied for the evaluation of the quality of compounding pharmacies in the state of Rio de Janeiro (Brazil). Solutions of 8-methoxypsoralen prepared in ethanol/water (30:70 v/v) produced fluorescence signals at excitation/emission wavelengths of 305/495 nm. The method presented good precision (relative standard deviation, RSD < 4.8%) and recoveries in the pharmaceutical samples from 88.5-108% indicated its feasibility. The results of assay (dosing) and uniformity of content suggested that two of the three evaluated pharmacies did not have appropriate techniques in the preparation of these formulations, which could potentially reduce the efficiency of dermatoses treatment. The implemented method is an alternative to those described in literature for pharmaceutical forms containing 8-methoxypsoralen.

Resumo em Inglês:

In this contribution we propose, for the first time, the use of Methylene Violet 3 RAX dye for the detection and determination of nitrite in cured meats and vegetables. Quantification is based on the decrease in absorbance of the dye, which is proportional to the nitrite concentration. The proposed method presents linear response (r > 0.99) in the range from 1.8 to 9 µmol L-1 of nitrite, with a limit of detection of 0.14 µmol L-1. Satisfactory accuracy with the official Association of Official Agricultural Chemists (AOAC) method was achieved, and the method was successfully applied to a wide range of cured meats and vegetables. The proposed method offers similar or superior performance to other optical methods used for the determination of nitrite in different matrices, with advantage in terms of reduction of chemical waste for each analysis, by minimizing amounts of reagents and products.

Resumo em Inglês:

This work performs an exploratory analysis of the sparkling wines from the state of Rio Grande do Sul, Brazil. Samples of traditional sparkling wine and Moscatel sparkling wine were analyzed and chemometrics tools were applied to physicochemical, gas chromatography and stable carbon isotope analysis. The carbon isotope ratio (δ13C-CO2) of the samples presents great heterogeneity and confirm that the isotopic signature of the CO2 could be derived from the fermentation of C4 sugar. The principal component analysis (PCA) was capable to discriminate and classify the samples in their respective groups and combined data approach was especially important to identify the correlation between the studied variables. With the increasing production of sparkling wines in Brazil, this work helps to evaluate the standards of the local sparkling wines.

Resumo em Inglês:

This work describes the development and characterization of triglyceride-based magnetic nanocomposites for application in magnetic hyperthermia and controlled drug delivery. The magnetic solid lipid nanocomposites (MSLN) constituted by mixtures of trilaurin-tricaprylin and trilaurin-tricaprin have been successfully obtained by emulsification-solvent evaporation method. The developed MSLNs were subjected to an external oscillating magnetic field and showed significant hyperthermia. The samples were exposed to frequencies of 688 and 869 kHz causing, respectively, a temperature increase of 15.5 and 22.7 °C (trilaurin-tricaprylin) and 17.3 and 26.1 °C (trilaurin-tricaprin). Also, in vitro assays in the absence of magnetic field showed that the triglyceride-based formulations were able first to encapsulate and then to sustained release an antitumoural hydrophobic drug. After 72 h of assay trilaurin-tricaprylin and trilaurin-tricaprin released 73 and 55% of their cargo, respectively. In addition, MSLN exhibited low in vitro cytotoxic activity against human neutrophils.

Resumo em Inglês:

The improvements on aluminosilicates dissolution through microwave-assisted acid decomposition procedures for Na and Al quantification by inductively coupled plasma optical emission spectrometry (ICP OES) are reported here. Complete dissolution of the samples is achieved employing 4 mL of HNO3 and 3-4 mL of HF thus reducing the total amount of these reactants in comparison with procedures found in the literature. Additionally, the type of crucibles used in the calcination for sample preparation step is also evaluated. Na and Al concentrations are in agreement with the expected values on the samples. Estimated silicon amount is achieved by difference of sodium and aluminum, and then Si/Al molar ratios were calculated for samples calcined in both porcelain (Si/Al is in the range 22-42) and platinum (Si/Al is in the range 27-40) crucibles, showing no difference between these procedures.

Resumo em Inglês:

Fe2O3 catalysts were prepared by co-precipitation method with the assistance of polyvinyl alcohol (PVA) for Fischer-Tropsch synthesis. Effects of PVA concentration on structure and performance of the catalyst were investigated in a fixed reactor at 230-310 °C, 1.5 MPa, 2000 h-1, and syngas H2/CO = 2.0. The catalysts were characterized by N2 adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), H2 or CO temperature-programmed reduction (TPR) and H2 temperature-programmed desorption (H2-TPD), Fourier transform infrared (FTIR) spectra and thermogravimetric analysis (TGA). It was found that there was strong interaction between Fe and PVA, which controlled the structure of the catalyst. Among the catalysts investigated, the catalyst prepared with 15 wt.% PVA exhibited better catalytic performance due to the dispersion of iron oxides and the formation of the more active phase on the catalyst. Meanwhile, this catalyst showed the high selectivity to heavy hydrocarbons and satisfactory thermal stability.

Resumo em Inglês:

A series of 2-hydroxy-3-arylnaphthalene-1,4-diones (3-aryllawsones) were synthesized by Suzuki-Miyaura cross coupling reaction of 3-iodolawsone with arylboronic acids/esters. The hydroxylated resulting products were transformed into their corresponding N,N-diethyl carbamates. The antineoplastic and antileishmanial activities of the compounds were evaluated and compared with lapachol and its carbamate, providing promising results.