Influence of the cultivation system in the aroma of the volatile compounds and total antioxidant activity of passion fruit

The aim of this study was to investigate the influence of the cultivation system on the volatile composition of the passion fruit and to determine the odoriferous contribution of the compounds for the aroma of the organic and conventional fruit, besides to assess the total antioxidant activity. The volatile compounds were isolated from dynamic headspace, separated by high-resolution gas chromatography and the odoriferous contribution to the passion fruit aroma was evaluated using the OSME technique. Total antioxidant activity was determined using the ABTS radical reaction. The organic and conventional passion fruit showed similar volatile profile, although some differences occurred. Ethyl 2-propenoate, 2-methyl-1-propanol, diethyl carbonate and ethyl hexanoate were threefold higher in the organic fruit while butyl acetate, hexanal, cis-3-hexenyl acetate and trans-3-hexenyl butanoate were threefold higher in the conventional fruit. Hexanoate and acetate esters, and saturated alcohols described as fruity, sweet, citrus and passion-fruit aroma showed the highest odorific intensity in the organic fruit. Furthermore, trans and cis-3-hexenyl acetate and alpha-copaene, alpha-terpineol, D-limonene, trans-beta-ocimene and delta-cadinene had higher contribution to the organic passion fruit aroma. On the other hand, unsaturated alcohols, beta-myrcene and beta-linalool described as grass, sulfur-like and passion-fruit aroma were higher in the conventional fruit. The organic passion fruit showed higher levels of total phenolic compounds and total antioxidant activity than the conventional fruit, suggesting that the cultivation system influenced the production of antioxidant bioactive compounds.     

Functionalization of wool with L‐cysteine: Process characterization and assessment of antimicrobial activity and cytotoxicity

In this study, we show that the plasma-initiated polymerization (PIP) can be carried out at ambient pressure using the dielectric barrier discharge (DBD) technology. The structure of styrene-maleic anhydride copolymer (SMA) is analyzed by ¹H and ¹³C-NMR. The effects of initiation time, gas flow rate, post-polymerization time, and temperature on yield are also discussed. The results show that SMA exhibits a dominant alternating structure. The yield of SMA increases with the increase of initiation time and polymerization temperature, remains unchanged with the increase of flow rate, and decreases rapidly with the increase of St-MAH molar ratio. The PIP in this experiment is shown to follow the free-radical polymerization mechanism and the process of the polymerization is also discussed. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Magnetite nanoparticles for functionalized textile dressing to prevent fungal biofilms development

ABSTRACT: The purpose of this work was to investigate the potential of functionalized magnetite nanoparticles to improve the antibiofilm properties of textile dressing, tested in vitro against monospecific Candida albicans biofilms. Functionalized magnetite (Fe3O4/C18), with an average size not exceeding 20 nm, has been synthesized by precipitation of ferric and ferrous salts in aqueous solution of oleic acid (C18) and NaOH. Transmission electron microscopy, X-ray diffraction analysis, and differential thermal analysis coupled with thermo gravimetric analysis were used as characterization methods for the synthesized Fe3O4/C18. Scanning electron microscopy was used to study the architecture of the fungal biofilm developed on the functionalized textile dressing samples and culture-based methods for the quantitative assay of the biofilm-embedded yeast cells. The optimized textile dressing samples proved to be more resistant to C. albicans colonization, as compared to the uncoated ones; these functionalized surfaces-based approaches are very useful in the prevention of wound microbial contamination and subsequent biofilm development on viable tissues or implanted devices.     

Detection and characterisation of a new metallocarboxypeptidase inhibitor from Solanum tuberosum cv. Desirèe using proteomic techniques

Protease inhibitors have been considered only as long as anti-nutritional factors, but have regained much interest in recent years because of their potential anti-cancer action and also because of its positive dietary effects. A new potato carboxypeptidase inhibitor (PCI) was isolated using proteomics techniques; the inhibitor was detected in an extract of Solanum tuberosum cv. Desirée by intensity fading MALDI-TOF mass spectrometry, and then was purified and characterised. The mass spectral from tryptic digestion (peptide mass fingerprint) was analysed with the “MASCOT search tool” and did not match any of the inhibitors of other plants. Protein identification and differentiation by peptide mass fingerprinting (PMF) has been adopted in our group as an excellent tool to differentiate, in fast an unequivocal way, proteins with very similar physicochemical and functional properties. The new PCI exhibited a molecular mass of 4218 Da and consists of a single polypeptide chain with an isoelectric point of 6.5. MALDI-TOF/TOF sequence analysis allowed determines a sequence belonging to the inhibitor.     

Modeling P(3HB) production by Bacillus megaterium

BACKGROUND: The poly(3‐hydroxybutyrate)—P(3HB)—is a polyester synthesized by many bacteria and stored as an energy reserve material in the cell cytoplasm as water‐insoluble inclusions. The aim of this research was to present a mathematical modeling approach in order to describe the culture kinetics of the bacterium Bacillus megaterium for the production of poly(3‐hydroxybutyrate). RESULTS: Four different models were proposed, differing in the expressions used for specific growth and polymer production rates. The predictions of these models were compared with experimental data and against the results of other models reported in the literature. CONCLUSION: Analysis of the experimental data under controlled and uncontrolled pH conditions showed that the inclusion of a correction factor for products formation, as well as a term related to the influence of H⁺ cations, are important for the correct modeling of this bioprocess. Compared with earlier models reported in the literature the proposed models show better fitting, with less or equal numbers of parameters, and provide parameter estimates with much lower variability. Copyright © 2011 Society of Chemical Industry     

The effect of nitrate, Fe(III) and bicarbonate on the degradation of bisphenol A by simulated solar UV-irradiation

The photoinitiated degradation of bisphenol A (BPA, 520 micromol/L) was investigated using a solar simulator in the absence/presence of NO(3)(-), Fe(III), and HCO(3)(-). The concentrations of NO(3)(-), Fe(III), and HCO(3)(-) were 0-160, 0-10, and 0-820 micromol/L, respectively, and were chosen to simulate a natural aquatic environment. The experimental region was explored using a Box-Behnken design for three factors, extended to experimentally include all eight possible combinations of presence/absence of the factors studied. The results show that, after 7h of irradiation, photolysis occurs only to a minimal degree (2%) in the absence of NO(3)(-) and HCO(3)(-). Increasing the concentration of NO(3)(-) and HCO(3)(-) gives rise to up to 24% degradation after 7h of irradiation. The concentration of Fe(III) was found to play no active role under the conditions studied. A simple linear model is given that very well describes the results obtained.     

Cadmium ion-selective sorbent preconcentration method using ion imprinted poly(ethylene glycol dimethacrylate-co-vinylimidazole)

The present study focuses on the preparation of an Cd²⁺-imprinted poly(ethylene glycol dimethacrylate-co-vinylimidazole) for selective extraction/preconcentration of Cd²⁺ ions from aqueous solution, with further determination by FAAS using a flow system. Sorbent extraction/preconcentration system was optimized by using chemometric tools (factorial design and Doehlert matrix). Under optimized conditions, the method presented a limit of detection of 0.11 μg L^?1 and linear analytical curve from 1.0 up to 50.0 μg L^?1 (r = 0.993). The preconcentration factor (PF), consumptive index (CI) and concentration efficiency (CE) were found to be 38.4, 0.39 mL and 14.3 min^?1, respectively. The selectivity coefficient of ion imprinted polymer was compared with the selectivity coefficient of NIP (non-imprinted polymer) for the Cd²⁺/Pb²⁺, Cd²⁺/Cu²⁺ and Cd²⁺/Zn²⁺ binary mixtures, where the respective values of relative selectivity coefficient (k′) of 157.5, 4.44 and 1.38 were obtained. The proposed method was successfully applied for cadmium determination in different types of water samples, urine and certified reference material (Lobster Hepatopancreas).     

Biocomposite membranes of sodium alginate and silk fibroin fibers for biomedical applications

Biocomposite membranes from biodegradable and biocompatible natural polymers were prepared from sodium alginate solution reinforced with silk fibroin fibers in several fiber content by casting and solvent evaporation. The properties of these biocomposites were investigated by scanning electron microscopy, swelling test, water vapor transmission, mechanical and thermal analyses, and cytotoxicity test. A biocomposite with uniform fiber dispersion and good fiber–matrix interaction was obtained through the incorporation of fibroin fibers in the alginate membrane, even though the fibers were used without any surface treatment to enhance the interfacial adhesion. The incorporation of fibroin fibers improved the tensile strength and also provided a new property to the alginate, that is, the resistance to tear. Moreover, the use of silk fibroin fibers in polymeric composites can result in a material with adequate characteristics for application in the biomaterial field, especially as wound dressings, because of its nontoxic effect to cells, flexibility, and resistance to tear. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3451–3457, 2013     

Epoxidation of modified natural plasticizer obtained from rice fatty acids and application on polyvinylchloride films

In recent years, much research effort has been driven to develop alternative plasticizers for medical and commodity plastic materials. In this study, a modified natural plasticizer, synthesized by esterification of rice fatty acids, was modified by epoxidation with peroxy acid generated in situ. Two natural epoxidized plasticizers were obtained, using peracetic acid (NP‐Ac) and peroctanoic acid (NP‐Oc) as reagent. PVC films after addition of these natural epoxidized plasticizers presented fairly good incorporation and plasticizing performance, as demonstrated by results of mechanical properties, T_g values (as shown by DSC), optical microscopy, exudation, and migration tests, FTIR and X‐ray diffraction obtained for plasticized PVC films. NP‐Ac plasticizer presented enhanced plasticizing performance compared with NP‐Oc, probably due to a higher epoxidation degree obtained in the reaction with peracetic acid. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Characteristics of PM2.5 Episodes Revealed by Semi-Continuous Measurements at the Baltimore Supersite at Ponca St

Highly time-resolved measurements of PM_2.5, its major constituents, particle size distributions (9 nm to 20 μ m), CO, NO/NO₂, and O₃, and meteorological parameters were made from February through November 2002, at the Baltimore Supersite at Ponca St. using commercial and prototype semi-continuous instruments. The average PM_2.5 mass concentration during the study period was 16.9 μ g/m³ and a total of 29 PM_2.5 pollution episodes, each in which 24-h averaged PM_2.5 mass concentrations exceeded 30.0 μ g/m³ for one or more days, were observed. Herein, 6 of the worst episodes are discussed. During these events, PM_2.5 excursions were often largely due to elevations in the concentration of one or two of the major species. In addition, numerous short-term excursions were observed and were generally attributable to local sources. Those in OC, EC, nitrate, CO, and NO_x levels were often observed in the morning traffic hours, particularly before breakdown of nocturnal inversions. Moreover, fresh accumulation aerosols from local stationary combustion sources were observed on several occasions, as evidenced by elevations in elemental markers when winds were aligned with sources resulting in PM_2.5 increments of ～ 17 μ g/m³. Overall, the results described herein show that concentrations of PM_2.5 and its major constituents vary enormously on time scales ranging from < 1 hr to several days, thus imposing a more highly complex pattern of pollutant exposure than can be captured by 24-hr integrated methods, alone. The data suggest that control of a limited number of local sources might achieve compliance with daily and annual PM_2.5 standards.