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This paper introduces for the first time the preparation of cobalt aluminate (CoAl2O4) nanoparticles through a solution combustion method using a Mentha piperita leaves extract. The active constituents present in the mentha leaves extract act as both a chelating and a reducing agent. The isolated precursor was characterized by FTIR, UV–Vis, thermal analysis and XPS. Various techniques (XRD, SEM and TEM, XPS, FTIR and UV–Vis) were also used to characterize the cobalt aluminate spinel from the point of view of structure, morphology and surface chemistry. XRD confirmed the formation of a single-phase, crystalline cubic spinel structure with mean crystalline domain size of 19.5 nm. The TEM analysis showed rhombic and rectangular CoAl2O4 nanoparticles with unimodal particle size distribution and average particle size of about 35 nm. The characteristic peaks of the CoAl2O4 spinel were highlighted by the FTIR spectrum. The tetrahedral configuration of Co2+ ions in the CoAl2O4 spinel structure was illustrated by the absorbance and XPS spectra. Furthermore, XPS spectra reveal both tetrahedral and octahedral configurations of Al3+ ions. To evaluate the catalytic properties of the cobalt aluminate, the photocatalytic degradation of methylene blue (MB) was carried out under visible light irradiation. [ABSTRACT FROM AUTHOR]

We report the first successful green synthesis route for organic transistors based on para-aminobenzoic acid (PABA) grafted to ferrite nanoparticles, at room temperature. The obtained core–shell nanoparticles (NCS) have been investigated by DLS, FT-IR, SEM, TEM. Both average hydrodynamic diameter and zeta potential of synthesized PABA-NCS nanoparticles has been identified, indicating a good stability of this nano-compound. SEM analysis proved a heterogeneous structured material with quasi-uniform granular formations in size, while TEM revealed a ferrite core of 20 nm. The measurements of output characteristics in the saturation regime and transfer characteristics at negative gate voltages have proved that an organic transistor based on PABA-NCS has been accomplished. The current increasing over a negative threshold voltage demonstrated an accumulation channel onset in the PABA-NCS thin film. This is a final argument for the p-type behavior of the PABA-NCS film. [ABSTRACT FROM AUTHOR]

In this study, hydroxyapatite (HAp) obtained by hydrothermal synthesis from natural sources (whelk shells of Rapana thomasiana) was compared to synthetic hydroxyapatite (prepared from chemical reagents) and used for 3D printing of HAp-based structures. Rapana thomasiana can be found in Romanian coast of Black Sea. The visceral part of Rapana is used for culinary purposes, but the whelk shell, mainly consisting of CaCO3, remains as biowaste and can be used as a source of Ca for hydroxyapatite synthesis. Synthetic and natural hydroxyapatite nanopowders were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), dynamic light scattering (DLS) method and in vitro tests. XRD and FT-IR have confirmed the formation of nanostructured hydroxyapatite irrespective of the raw material used. Both types of powders were further used for 3D printing of HAp-based structures, which have also been characterized by SEM and in vitro tests. In vitro tests performed on natural HAp disks (made from whelk shell) lack cytotoxicity and were associated with cell viability similar to that for the synthetic hydroxyapatite disk. [ABSTRACT FROM AUTHOR]

One of the most promising ways for the realization of multi-functional materials is the integration of oxides with different properties in artificial heterostructures. In this paper, a novel piezoelectric-ferromagnetic heterostructure consisting of 0.92Na0.5Bi0.5TiO3-0.08BaTiO3 (abbreviated as BNT-BT0.08) and CoFe2O4 layers is fabricated on Si-Pt substrate, by sol-gel method coupled with spin-coating technique. The composite thin film shows only perovskite Bi0.5Na0.5TiO3-like rhombohedral phase and CoFe2O4 cubic phase. The thickness of CoFe2O4 and BNT-BT0.08 layers is ~ 280 and ~ 400 nm, respectively. BNT-BT0.08/CoFe2O4 heterostructure thin film shows a saturation magnetization of 0.11 emu/g at 5 K and 0.07 emu/g at 295 K, dielectric constant of 235 at 1 kHz and tunability of 70% at 1 kHz and an electric field E = 110 kV/cm. The results reveal that the investigated hybrid piezoelectric/ferromagnetic structure shows piezoelectric behavior, good ferroelectric and ferromagnetic properties. This bilayer composite can be used in miniature low-frequency magnetic sensor and piezoelectric sensor for biomedical domain. [ABSTRACT FROM AUTHOR]

The aim of this research was to develop advanced lipid nanocarriers based on renewable vegetable resources (rice bran oil and raspberry seed oil) that possess self-antioxidative properties, having advantages in terms of minimal side effects and exhibiting the ability to simultaneously co-encapsulate and co-release two active compounds. The focus has been oriented towards developing safe cosmetic formulations with broad-spectrum photoprotection based on these new lipid nanocarriers that contain large amounts of vegetable oils and low concentrations of synthetic UVA and UVB filters (butyl-methoxydibenzoylmethane – BMDBM and octocrylene – OCT). The lipid nanocarriers have a spherical shape and show good physical stability, with a zeta potential in the range of −25.5 to −32.4 mV. Both vegetable oils play a key role in the preparation of efficient nanocarriers, leading to a less ordered arrangement of the lipid core that offers many spaces for the entrapment of large amounts of BMDBM (79%) and OCT (90%), as wells as improved antioxidant activity and UV absorption properties, particularly for the lipid nanocarriers prepared from rice bran oil. By formulating the lipid nanocarriers into creams containing only 3.5% of the UV filters and 10.5% of the vegetable oils, the resulting sunscreens exhibited improved photoprotection, reflecting up to 91% and 93% of UVA and UVB rays, respectively. A new direction of research achieved by this study is the multiple release strategy of both UV filters from the same lipid nanocarrier. After 24 hours, a slow release of BMDBM (less than 4%) and OCT (17.5%) was obtained through a Fick diffusion process. This study demonstrates a significant advance in the areas of both nanotechnology and cosmetics, developing safer cosmetic formulations that possess broad antioxidant, photoprotective and co-release effectiveness due to the existence of a high content of nanostructured vegetable oils combined with a low amount of synthetic UV filters in the same carrier system. [ABSTRACT FROM AUTHOR]