Absence of ferromagnetism in ferroelectric Mn-doped BaTiO3 nanofibers

Pure and Mn-doped barium titanate nanofibers were synthesized by the electrospinning method. The morphology, microstructure and crystal structure of as-spun and annealed composite nanofibers were characterized by scanning electron microscopy and transmission electron microscopy. After annealing at 850°C, we obtain nanofibers a few μm long, formed by nanoparticles of irregular shape with sizes around 100 nm. X-ray diffraction and Raman spectroscopy show that a partial phase transition from tetragonal to hexagonal takes place for BaTi_0.90Mn_0.10O₃. Vibrational phonon modes were calculated for BaTiO₃ within the density functional theory (DFT) framework. Ferroelectricity has been probed on pure and Mn-doped BaTiO₃ nanofibers, by means of piezoresponse force microscopy in an atomic force microscope, confirming the polar domain switching behavior of the fibers. The measured piezoelectric coefficient d₃₃ were 31 and 22 pm/V for BaTiO₃ and BaTi_0.90Mn_0.10O₃. Magnetic properties of the samples were probed in a superconducting quantum interference device. Diamagnetic and paramagnetic behaviors were found in pure and Mn-doped samples, respectively.     

Temperature stimuli-responsive nanoparticles from chitosan-graft-poly(N-vinylcaprolactam) as a drug delivery system

This work describes the preparation of thermosensitive chitosan-graft-poly(N-vinylcaprolactam) nanoparticles by ionic gelation and their potential use as a controlled drug delivery system, using doxorubicin as a model drug. A systematic study of the effect of the main processing parameters on both the size and thermoresponsive behavior of nanoparticles was investigated. The size of the particles is strongly dependent on the length of the poly(N-vinylcaprolactam) grafted chains and the concentration of the copolymer and crosslinking agent solutions. The molecular structure of the copolymer plays an essential role in the phase transition temperature of the particles, which decreases with the length of PVCL grafted chain. The system displayed proper drug-association parameters, and the drug-loaded nanoparticles exhibited dose-dependent cytotoxicity. A significant increase in the doxorubicin delivery rate was observed above the phase transition temperature (40 °C). These features indicate that these nanoparticles are suitable for the development of a new thermally controlled anti-cancer drug delivery system. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47831.     

Assessment of the Physicochemical Properties and Oxidative Stability of Kernel Fruit Oil from the Acrocomia totai Palm Tree

This study investigated the effects of variations in oil contents and fatty-acid composition, density, viscosity, acid values, saponification values, specific oxidative stability, and antioxidant concentration of Acrocomia totai kernel oil during fruit maturation. Fatty acids were quantified using ¹H nuclear magnetic resonance (NMR) spectroscopy, gas chromatograph-flame-ionization detector (GC-FID), and Fourier transform Raman (FT-Raman) spectroscopy analyses. The results showed that all physicochemical characteristics and oil composition changed during the ripening stage. The CG-FID analysis showed a reduction in the unsaturated fatty-acid content (from 78.8% to 22.1%), with a proportional increase in the saturated fatty-acid contents (from 21.6% to 77.9%). The difference in the fatty-acid composition was confirmed by analysis of the ¹H NMR and FT-Raman spectra. The degree of unsaturation was calculated to determine the oxidative stability of oil. These results suggest that the fruit's maturation contributes to the specific oxidative stability. The antioxidant concentration revealed higher contents of carotenoids in the ripe fruit (0.16 mg of carotenoid per 100 g_KERNEL) when compared to the unripe fruit (0.05 mg of carotenoid per 100 g_KERNEL). In the total phenolics analysis, there was no change in concentration over ripening time. These results show that kernel oil has physicochemical properties comparable with high-quality commercial vegetable oils, suggesting that it is a promising alternative to conventional vegetable oils.     

Periodic Copula Autoregressive Model Designed to Multivariate Streamflow Time Series Modelling

Water Resources Management - It is a challenge to develop models that can represent the stochastic behaviour of rivers and basins. Currently used streamflow models were constructed under rigid...     

Property specification patterns at work: verification and inconsistency explanation

Innovations in Systems and Software Engineering - Property specification patterns (PSPs) have been proposed to ease the formalization of requirements, yet enable automated verification thereof. In...     

Evaluation of the pore morphology formation of the Freeze Foaming process by in situ computed tomography

The so-called Freeze Foaming method aims at manufacturing ceramic cellular scaffolds for diverse applications. One application is dedicated to potential bone replacement material featuring open, micro and interconnected porosity. However, the main challenges of this foaming method is to achieve a homogeneous pore morphology. In a current project, the authors throw light on the bubble/pore and strut formation of this process by in situ computed tomography. This allows for evaluating varying process parameter’s effects on the growth of the ceramic foam during the foaming process. As first result and basis for CT analysis, a stable and reproducible model suspension was developed which resulted in reproducible foam structures. In dependence of selected process parameters like pressure reduction rate or air content in the ceramic suspension resulting Freeze Foams became adjustable with regard to their pore morphology. Pore size and distribution data as well as the porosity were characterized and evaluated accordingly.     

Bioactive Phytochemicals from Wild Arbutus unedo L. Berries from Different Locations in Portugal: Quantification of Lipophilic Components

The lipophilic composition of wild Arbutus unedo L. berries, collected from six locations in Penacova (center of Portugal), as well as some general chemical parameters, namely total soluble solids, pH, titratable acidity, total phenolic content and antioxidant activity was studied in detail to better understand its potential as a source of bioactive compounds. The chemical composition of the lipophilic extracts, focused on the fatty acids, triterpenoids, sterols, long chain aliphatic alcohols and tocopherols, was investigated by gas chromatography–mass spectrometry (GC–MS) analysis of the dichloromethane extracts. The lipophilic extractives of the ripe A. unedo berries ranged from 0.72% to 1.66% (w/w of dry weight), and consisted mainly of triterpenoids, fatty acids and sterols. Minor amounts of long chain aliphatic alcohols and tocopherols were also identified. Forty-one compounds were identified and among these, ursolic acid, lupeol, α-amyrin, linoleic and α-linolenic acids, and β-sitosterol were highlighted as the major components. To the best of our knowledge the current research study provides the most detailed phytochemical repository for the lipophilic composition of A. unedo, and offers valuable information for future valuation and exploitation of these berries.