Correlating the effect of preparation methods on the structural and magnetic properties, and reducibility of CuFe2O4 catalysts.

CuFe2O4 spinel oxide has attracted research interest because of its versatile practical applications, especially for catalysis. In this study, nanometre-sized CuFe2O4 particles were prepared by three different methods, including nanospace confinement in SBA-15, hard template removal, and sol-gel combustion. The relationship between structure, size, magnetic behaviour, and reducibility of the catalysts was further investigated by various advanced techniques. Samples prepared by impregnation and hard template removal show high surface area and small crystallite size with superparamagnetic behaviour. In contrast, the sol-gel sample exhibits ferromagnetic properties with a large crystallite size and low surface area. Although all samples present a tetragonal crystal structure, the distributions of Fe and Cu cations in tetrahedral and octahedral sites in the spinel structure are different. The reducibility results demonstrate that the supported CuFe2O4/SBA-15 shows the lowest reduction profile. These results could suggest that the synthesis method strongly affects the crystal properties and cation distribution in the spinel structure, microstructure, surface area and reducibility, which are among the most relevant physicochemical properties for the catalytic activity.

In Situ X-ray Absorption Fine Structure Probing-Phase Evolution of CuFe2O4 in Nanospace Confinement.

The thermal transformation of Cu(NO3)2 and (Fe(NO3)3 into a CuFe2O4 spinel structure in the confined space of SBA-15 has been investigated. Interestingly, we observed the new formation mechanism of CuFe2O4 in SBA-15 via isolated metal ions (Cu2+ and Fe3+) surrounded by oxygen atoms, which gradually transformed to CuO and ferrihydrite. The latter evolved to maghemite spinel ferrite and reacted with CuO to form CuFe2O4 as the final species. In contrast, in the nonconfined space where the spinel was produced via a sol-gel combustion method, the nanostructure of CuFe2O4 immediately formed during the sol-gel combustion process and its crystallinity was improved after calcination. This is the first report on probing-phase formation using high-temperature in situ X-ray absorption fine structure.

SUT-NANOTEC-SLRI beamline for X-ray absorption spectroscopy.

The SUT-NANOTEC-SLRI beamline was constructed in 2012 as the flagship of the SUT-NANOTEC-SLRI Joint Research Facility for Synchrotron Utilization, co-established by Suranaree University of Technology (SUT), National Nanotechnology Center (NANOTEC) and Synchrotron Light Research Institute (SLRI). It is an intermediate-energy X-ray absorption spectroscopy (XAS) beamline at SLRI. The beamline delivers an unfocused monochromatic X-ray beam of tunable photon energy (1.25-10 keV). The maximum normal incident beam size is 13 mm (width) × 1 mm (height) with a photon flux of 3 × 108 to 2 × 1010 photons s-1 (100 mA)-1 varying across photon energies. Details of the beamline and XAS instrumentation are described. To demonstrate the beamline performance, K-edge XANES spectra of MgO, Al2O3, S8, FeS, FeSO4, Cu, Cu2O and CuO, and EXAFS spectra of Cu and CuO are presented.

The effects of metal ions in Euphorbia cf. lactea latex on the fibrinogenolytic activity of a plant protease.

Two synchrotron-based techniques, synchrotron X-ray fluorescence (SXRF) and X-ray absorption spectroscopy (XAS), have demonstrated that Ca(2+) and Zn(2+) were the major metal ions distributed in the natural latex of Euphorbia cf. lactea. Both metal ions were found to affect the fibrinogenolytic activity of a homodimeric protease purified from the latex of this plant. The dimeric protein had an estimated molecular mass of about 82 kDa analyzed by SDS-PAGE. Therefore this protein was called as EuP-82. Based on the results of circular dichroism (CD) spectroscopy and the fibrinolytic activity measurement, it was found that Ca(2+) could activate the proteolytic activity of the enzyme by stabilizing its backbone structure. The intact conformation of EuP-82 was predicted from CD spectrum, which consisted of 51 % α-helix and 9 % ß-sheet. Zn(2+) (10 mM) could decrease the fibrinolytic activity of EuP-82 to 30 ± 1 %. CD spectrum also supported that the inhibitory effect of Zn(2+) on the enzyme activity occurred by the drastic change of the enzyme structure with increasing the random coil conformation and by switching between α-helix and ß-sheet structure. These results could be of first importance for further application to use EuP-82, the natural source protease as a potential drug for the thrombosis treatment. The fibrinolytic activity of EuP-82 may be enhanced by plasma Ca(2+) which generally involves in human hemostasis system.

Performance and status of beamline BL8 at SLRI for X-ray absorption spectroscopy.

Beamline BL8 of the Synchrotron Light Research Institute (Thailand) is routinely operated for X-ray absorption spectroscopy (XAS) in an intermediate photon energy range (1.25-10 keV). The photon energy is scanned by using a double-crystal monochromator, the crystal pair of which can be interchanged among KTP(011), InSb(111), Si(111) and Ge(220). The experimental set-up conveniently facilitates XAS measurements in transmission and fluorescence-yield modes at several K-edges of elements ranging from magnesium to zinc. Instrumentation and specification of the beamline and the XAS station are described, together with the determination of the available photon flux [0.1-6 × 10(10) photon s(-1) (100 mA)(-1)], energy resolution (1-5 × 10(-4)) and stability of photon energy calibration (0.07 eV), representing the beamline performance. Data quality and accuracy of XANES and EXAFS measured at BL8 are compared with those of other well established beamlines. A noted distinction of BL8 is its relatively high sensitivity for studying phosphorous, sulfur and chlorine in diluted systems and its maximum beam size of 14 mm (width) × 1 mm (height), which is suitable for bulk characterization.

Elucidating the genesis of Bi2MoO6 catalyst by combination of synchrotron radiation experiments and Raman scattering.

Combination of in situ Raman scattering with high-resolution XRD and XAS techniques has proven to be a powerful tool to elucidate the crystal growth of gamma-Bi2MoO6 under hydrothermal conditions.