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It is presented a green synthesis method to obtain hematite (or magnetite) as a function of the concentration of Coffea arabica L extract mixed with a single iron salt precursor. The crystal structure, microstructural and phase formation of the iron oxide nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy and DC magnetometry. The particle sizes of the obtained nanoparticles are of the order of 5 nm. Optical properties were studied with UV–Vis spectroscopy from which a band gap energy of Eg = 3.09 eV for hematite and Eg = 3.23 eV for magnetite were deduced. The photocatalytic activity of the synthesized nanoparticles was tested by degradation of methyl orange dye under UV radiation, showing their potential application in wastewater treatment. [ABSTRACT FROM AUTHOR]

High-quality nanometric and homogeneous particles of Cu–doped PrCrO3 ceramic compounds were synthesized by the hydrothermal-assisted sol–gel method. Structural, chemical state, morphology, and magnetic properties were investigated in the PrCr1−xCuxO3 orthochromite with 0 ≤ x ≤ 0.1 composition. XRD patterns show a complete solubility of the Cu ion, as well as an increase of the orthorhombic cell volume. The microstructural analysis (SEM) shows that the nanometric-size particles obtained from the synthesis process coalesce during the subsequent high-temperature process. In addition, XPS analysis revealed that the solubility and charge compensations by aliovalent Cu2+ ions substitution are driven by the change of the oxidation state from Cr3+ to Cr5+ and Cr6+. These results produce novel changes in the magnetic properties. There, the ZFC-mode shows negative magnetization in all investigated samples, and it is discussed as an intrinsic phenomenon in terms of the Γ2 (Fx, Cy, Gz) spin configuration as well as the arising of the diamagnetic Cr6+ (do). It is noted that Cr6+ tunes the diamagnetic magnitude during the ZFC protocol. On the other hand, different oxidation states are observed at the Cr site in PrCrO3, whose final result is an increase of the coercivity field, Hc, and the remanent magnetization, Mr, in the M–H curves. The increase of ferromagnetic and the antiferromagnetic domains sharing the same volume leads to an anisotropic magnetic interaction, called exchange-bias effect. It is observed that the Cu-doped PrCrO3 decreases the exchange-bias effect, but at the same time an increase in the magnetic properties is observed at 2 K. [ABSTRACT FROM AUTHOR]

Abstract: Cu/ZrO2, Ni/ZrO2 and bimetallic Cu–Ni/ZrO2 catalysts were prepared by deposition–precipitation method to produce hydrogen by oxidative steam reforming of methanol (OSRM) reaction in the range of 250–360°C. TPR analysis of the Cu–Ni/ZrO2 catalyst showed that the presence of Cu facilitates the reduction of the Ni at lower temperatures. In addition, this sample showed two reduction peaks, the former peak was attributed to the reduction of the adjacent Cu and Ni atoms which could be forming a bimetallic Cu-rich phase, and the second was assigned to the remaining Ni atoms forming bimetallic Ni-rich nanoparticles. Transmission Electron Microscopy revealed Cu or Ni nanoparticles on the monometallic samples, while bimetallic nanoparticles were identified on the Cu–Ni/ZrO2 catalyst. On the other hand, Cu–Ni/ZrO2 catalyst exhibited better catalytic activity than the monometallic samples. The difference between them was related to the Cu–Ni nanoparticles present on the former catalyst, as well as the bifunctional role of the bimetallic phase and the support that improve the catalytic activity. All the catalysts showed the same selectivity toward H2 at the maximum reaction temperature and it was ∼60%. The high selectivity toward CO is associated to the presence of the bimetallic Ni-rich nanoparticles, as evidenced by TEM–EDX analysis, since this behavior is similar to the one showed by the monometallic Ni-catalyst. [Copyright &y& Elsevier]

The use of three-dimensional porous scaffolds derived from decellularized extracellular matrix (ECM) is increasing for functional repair and regeneration of injured bone tissue. Because these scaffolds retain their native structures and bioactive molecules, in addition to showing low immunogenicity and good biodegradability, they can promote tissue repair and regeneration. Nonetheless, imitating these features in synthetic materials represents a challenging task. Furthermore, due to the complexity of bone tissue, different processes are necessary to maintain these characteristics. We present a novel approach using decellularized ECM material derived from bovine cancellous bone by demineralization, decellularization, and hydrolysis of collagen to obtain a three-dimensional porous scaffold. This study demonstrates that the three-dimensional porous scaffold obtained from bovine bone retained its osteoconductive and osteoinductive properties and presented osteogenic potential when seeded with human Wharton's jelly mesenchymal stromal cells (hWJ-MSCs). Based on its characteristics, the scaffold described in this work potentially represents a therapeutic strategy for bone repair.

The photocatalytic activity in the degradation of 4-chlorophenol (4-ClPh) in aqueous medium (80 ppm) using 2.0 wt% Ag/Al 2 O 3 -Gd 2 O 3 (Ag/Al-Gd- x ; where x = 2.0, 5.0, 15.0, 25.0 and 50.0 wt% of Gd 2 O 3 ) photocatalysts prepared by the sol-gel method was studied under UV light irradiation. The photocatalysts were characterized by N 2 physisorption, X-ray diffraction, SEM, HRTEM, UV-Vis, XPS, FTIR and fluorescence spectroscopy. About 67.0% of 4-ClPh was photoconverted after 4 h of UV light irradiation using Ag/γ--Al 2 O 3 . When Ag/Al-Gd- x photocatalysts were tested, the 4-ClPh photoconversion was improved and more than 90.0% of 4-ClPh was photoconverted after 3 h of UV light irradiation in the materials containing 15.0 and 25.0 wt% of Gd 2 O 3 . Ag/Al-Gd-25 was the material with the highest efficacy to mineralize dissolved organic carbon, mineralizing more than 85.0% after 4 h of UV light irradiation. Silver nanoparticles and micro-particles of irregular pentagonal shape intersected by plane nanobelts of Al 2 O 3 -Gd 2 O 3 composite oxide were detected in the Ag/Al-Gd-25 photocatalyst. This material is characterized by a lowest recombination rate of electron-hole pairs. The low recombination rate of photo-induced electron-hole pairs in the Ag/Al-Gd- x photocatalysts with high Gd 2 O 3 contents (≥15.0 wt%) confirmes that the presence of silver nanoparticles and microparticles interacting with Al 2 O 3 -Gd 2 O 3 composite oxide entities favors the separation of photo-induced charges (e - and h + ). These materials could be appropriate to be used as highly efficient photocatalysts to eliminate high concentrations of 4-ClPh in aqueous medium., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Clinical procedures when shear forces are applied to brackets suggest adhesion forces between 2.8 and 10.0 MPa as appropriate. In this study dental enamel was evaluated by scanning electron microscopy (SEM) before and after removing the brackets. Thirty bicuspids (previous prophylaxis) with metallic brackets (Roth Inovation 0.022 GAC), Transbond Plus SEP 3M Unitek adhesive and Transbond XT 3M resin were used. The samples were preserved to 37°C during 24 hr and submited to tangential forces with the Instron Universal machine 1.0 mm/min speed load strength resistance debonding. Also the Adhesive Remanent Index (ARI) test was made, evaluating the bracket base and the bicuspid surface. All the bracket SEM images were processed with AutoCAD to determine the enamel detached area. The average value was 6.86 MPa (SD ± 3.2 MPa). ARI value 1= 63.3%, value 2= 20%, value 3= 13.3% and 33% presented value 0. All those samples with dental enamel loss, presented different situations as fractures, ledges, horizontal, and vertical loss in some cases, and some scratch lines. There is no association between the debonding resistance and enamel presence. Less than half of the remanent adhesive on the dental enamel was present in most of the samples when the ARI test was applied. When the resin area increases, the debonding resistance also increases, and when the enamel loss increases, the resin free metallic area of the bracket base decreases in the debonding., (© 2017 Wiley Periodicals, Inc.)

One of the main disadvantages of MTA is its long setting time which could result in higher solubility and microleakage, producing a failed treatment. Studies have shown that the addition of bioactive glass may decrease the setting time. The aim of this study is to evaluate the compressive strength, setting time, solubility and radiopacity of a MTAlike experimental cement to which different percentage of wollastonite and bioactive glass are added. White MTA Angelus® was used as control; an experimental MTA-like cement (ExpC) was prepared using white Portland cement with 20wt% of Bi 2 O 3 ; three wollastonite cement composites were prepared adding 10, 20 and 30wt% of wollastonite to ExpC, and three more adding the same proportions of bioactive glass. Compressive strength was tested according to ADA 30; radiopacity, setting time and solubility were tested according to ISO 6876. SEM observations of the surface were made after the solubility test. Compressive strength, setting time, solubility and radiopacity were reduced as the wollastonite increased; solubility increased with the addition of bioactive glass. The surfaces of MTA Angelus® and ExpC were smoother than Wollastonite and Bioactive glass groups. Addition of wollastonite and bioactive glass improved the physical properties of a MTA-like experimental cement, reducing the setting time with good solubility percentages, which would be an advantage in its clinical use., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The interest of microelectronics industry in new organic compounds for the manufacture of luminescent devices has increased substantially in the last decade. In this paper, we carried out a study of the usage feasibility of three organic bidentate ligands (2,6-dihydroxyanthraquinone, anthraflavic acid and potassium derivative salt of anthraflavic acid) for the synthesis of an organic semiconductor based in silicon phthalocyanines (SiPcs). We report the visible photoluminescence (PL) at room temperature obtained from thermal-evaporated thin films of these new materials. The surface morphology of these films was analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM indicated that the thermal evaporation technique is an excellent resource in order to obtain low thin film roughness when depositing these kinds of compounds. Fourier transform infrared spectroscopy (FTIR) spectroscopy was employed to investigate possible changes in the intra-molecular bonds and to identify any evidence of crystallinity in the powder compounds and in the thin films after their deposition. FTIR showed that there was not any important change in the samples after the thermal deposition. The absorption coefficient (α) in the absorption region reveals non-direct transitions. Furthermore, the PL of all the investigated samples were observed with the naked eye in a bright background and also measured by a spectrofluorometer. The normalized PL spectra showed a Stokes shift ≈ 0.6 eV in two of our three samples, and no PL emission in the last one. Those results indicate that the Vis PL comes from a recombination of charge carriers between conduction band and valence band preceded by a non-radiative relaxation in the conduction band tails.