Alkyl phosphonium-based ionic liquids as promising additives for the corrosion protection of epoxy coatings in saline medium: Effect of the anion

Alkyl phosphonium-based ionic liquids (ILs), namely trihexyl(tetradecyl)-phosphonium chloride (P₆₆₆₁₄Cl), ethyl-(tributyl)-phosphonium diethyl phosphate (P₄₄₄₂[dep]), trihexyl(tetradecyl)-phosphonium bis(trifluorosulfonyl)imide (P₆₆₆₁₄[TFSI]), and trihexyl(tetradecyl)-phosphonium zinc tetrachloride ([P₆₆₆₁₄]₂[ZnCl₄]) were used for the first time as anticorrosive additives for epoxy coatings on AISI 1020 carbon steel plates. The corrosion protection performance of intact and artificially scratched coatings was evaluated in 3.5 wt% NaCl aqueous solution by electrochemical impedance spectroscopy. Regarding the intact coatings, those containing 0.5 phr of [P₆₆₆₁₄]₂[ZnCl₄] and 1.0 phr of P₆₆₆₁₄[TFSI] and P₄₄₄₂[dep] presented excellent corrosion resistance up to 720 h of immersion with |Z|_f=0.01Hz values higher than 10¹⁰ Ω cm². The scratched coatings loaded with P₄₄₄₂[dep] displayed the best anticorrosive response after 168 h of immersion. Furthermore, these coatings and that loaded with 0.5 phr of [P₆₆₆₁₄]₂[ZnCl₄] displayed an increase of corrosion resistance with increasing the immersion time, suggesting the formation of a passivating layer at the epoxy–substrate interface. The inhibition characteristic of the corresponding anions in the IL component contributes for this behavior. The hydrophobic characteristic of the coatings before and after the immersion in the saline solution was studied by measuring the water contact angle. Furthermore, the adhesion strength after immersion was also investigated by pull-off testing.     

Pro‐oxidant and Antioxidant Effects in Photodynamic Therapy: Cells Recognise that Not All Exogenous ROS Are Alike

Photodynamic therapy (PDT) uses light, photosensitizer molecules and oxygen to generate reactive oxygen species (ROS) that kill cancer cells. Redaporfin, a new photosensitizer in clinical trials, generates both singlet oxygen and superoxide ions. We report the potentiation of redaporfin–PDT in combination with ascorbate and with the inhibition of antioxidant enzymes in A549 (human lung adenocarcinoma) and CT26 (mouse colon adenocarcinoma) cells. The addition of ascorbate and the inhibition of superoxide dismutase (SOD) strongly increased the phototoxicity of redaporfin towards A549 cells but not towards CT26 cells. The inhibition of catalase and the depletion of the glutathione pool also potentiate redaporfin–PDT towards A549 cells. The lower SOD activity of A549 cells might explain this difference. SOD activity levels may be explored to increase the selectivity and efficacy of PDT with photosensitizers that generate radical species.     

Synthesis of hexyl butyrate (apple and citrus aroma) by Candida rugosa lipase immobilized on Diaion HP-20 using the Box-Behnken design

Food Science and Biotechnology - This study aims at the synthesis of hexyl butyrate by Candida rugosa lipase (CRL) immobilized on Diaion HP 20. The lipase load used was...     

Maghemite Interparticle Interactions in γ–Fe2O3/Ag nanocomposites

Maghemite and silver nanoparticles were prepared using the ionic coordination reaction technique. X-ray diffractograms (XRD) show that all the samples have a high degree of purity. The average particle sizes obtained by XRD and transmission electron microscopy (TEM) vary from 9 to 13 nm for the γ–Fe₂O₃ particles and from 130 to 142 nm for the Ag particles. The magnetic properties of the samples have been studied by room-temperature DC magnetization and Mössbauer spectroscopy. These measurements indicate the presence of γ–Fe₂O₃ particles with interparticle interactions of varying strength, resulting in three magnetic regimes: superparamagnetic, superparamagnetic with interactions, and blocked with interactions.     

Influence of different percentages of N‐phenylaminopropyl—poss on the degradation kinetic of epoxy resin

In the present study, nanocomposites were prepared with different contents (1, 2, 5, 10% by weight) of polyhedral oligomeric silsesquioxane—POSS n‐phenylaminopropyl in an epoxy matrix. The samples were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and X‐ray diffraction (XRD). TGA analyses were performed at different heating rates to allow for the prediction of the kinetic parameters of degradation. XRD analyses were used to calculate the average molecular interchain spacing. TGA analysis showed that the presence of POSS increased the thermal stability of the nanocomposites. An increase in the activation energy on degradation was evidenced through the kinetic parameters, especially for the 10% POSS. Moreover, the addition of POSS changed the kinetic mechanism of the deceleratory mode (F_n) in favor of the diffusion (D_n) process. The diffusion mechanism is corroborated by the XRD analyses that showed the increase of distance between chains when was added POSS. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Poly(lactic acid) biocomposites with mango waste and organo-montmorillonite for packaging

Poly(lactic acid) (PLA) is a biodegradable polymer used in packaging, but its properties can be improved by manufacturing composite matrixes. The combination of PLA, starch, and nano-montmorillonite leads to materials with superior mechanical properties. Mango lump is rich in cellulose and starch. The goal of this study is to develop and characterize biocomposites based on PLA, mango waste, and nano-organo-montmorillonite for packaging. The samples were microstructurally, morphologically, and mechanically characterized. Physical interaction between the phases was observed. The mango components displaced the PLA X-ray diffraction peaks and the clays altered their intensity, by interfering with chain packing. The addition of single components to PLA increased the samples’ transition temperatures, but the addition of multiple components diminished them. PLA showed adhesiveness to cellulose fibers and nonadhesiveness to starch granules. Thicker samples presented better mechanical properties. PLA–mango–“chocolate clay” samples are relatively stable materials, while PLA–mango–“bofe clay” samples could represent promising highly biodegradable materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47512.     

Synthesis and characterization of biocomposites with different hydroxyapatite–collagen ratios

Hydroxyapatite (HA)-type I collagen (Col) composite is a tissue-engineered bone graft which can act as a carrier or a template structure for cells or any other agents. In this paper, the effect of Col ratio on the scaffold structure and composition was analyzed. Scaffolds composed by HA/Col with different weight ratios (80:20; 50:50; 20:80, and 10:90) were produced by the precipitation method at pH 8–9, 37°C and 6 h of ripening. Using X-ray diffraction data, the Rietveld structure refinement showed that the size of HA crystals along the c-axis direction (002) decreases significantly in the presence of Col. Thus, the HA crystal shape turned from needle-like in pure HA, into spherical, in the 10:90 composite due to Col fibrillogenesis. The homogeneity of the composite was significantly dependent on the amount of Col in it. HA/Col 20/80 composite presented HA particles in a more homogenous way. Such a biocomposite was successfully produced in a rapid way and it is potentially useful for both small tissue repairs and engineering.     

Evaluation of some metals in Brazilian coffees cultivated during the process of conversion from conventional to organic agriculture

The aim of this study was to evaluate the presence of nutrients and toxic elements in coffees cultivated during the process of conversion, on organic agriculture, in southwest Bahia, Brazil. Levels of the nutrients and toxic elements were determined in samples of soils and coffee tissues from two transitional organic farms by atomic absorption spectrometry (FAAS). The metals in soil samples were extracted by Mehlich1 and USEPA-3050 procedures. Coffee samples from both farms presented relatively high levels of Cd, Zn and Cu (0.75, 45.4 and 14.9 μg g⁻¹, respectively), but were still below the limits specified by the Brazilian Food Legislation. The application of statistical methods showed that this finding can be attributed to the addition of high amounts of organic matter during the flowering tree period which can act on the bioavailability of metal ions in soils.     

Social nesting: Changes in social network and support across the transition to parenthood in couples that conceived spontaneously or through assisted reproductive technologies.

Research showed that following the birth of a first child, parents increase contact with family members and diminish contact with friends, however, these changes may differ when conception is achieved through assisted reproductive technologies (ART). Based on the convoy model (Kahn & Antonucci, 1980) perspective of close relationships, we examined changes across the transition to parenthood in the social networks and support of men and women that conceived spontaneously or through ART. Thirty one women and 22 men (22 couples) that conceived through ART and 28 women and 24 men (24 couples) with a spontaneous conception provided data on social network and support from nuclear family, extended family, and friends twice: at 24-weeks pregnancy and 4-months postpartum. Results demonstrated that, regardless of method of conception, during the transition to parenthood new parents showed a strong nesting movement towards their nuclear family, perceiving increasing levels of nuclear family support across time. Extended family seemed to have only a secondary role on the social nesting movement and a withdrawal from friends was also observed. Considering the primary role nuclear family members seem to have on providing effective support to child-rearing, a greater emphasis on the importance of parents’ relationship with their own parents and siblings could be made and social and working policies that prevent the displacement of families geographically also should be considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)