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A series of Pt–Co bimetallic nanoparticles with different Pt/Co atomic ratios were prepared on ionic liquid-modified SBA-15 for selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) under solvent-free reaction conditions. The addition of Co significantly modified the electronic properties of Pt and affected the activity of the prepared bimetallic nanoparticles. Removal of Cl from Pt in NaBH4 solution was more effective with higher amounts of Co, which promoted the formation of a Pt–Co alloy in the sample and further increased the charge density of Pt due to charge transfer from Co to Pt on the nanoparticles, as revealed by XAFS. The presence of Ptδ− and Coδ+ in the bimetallic nanoparticles promotes hydrogen dissociation and CAL adsorption via CO. The activity and COL selectivity of bimetallic catalysts gradually improved when the Pt/Co ratios decreased from 3:1 to 1:3. The highest performance was achieved over PtCo3/IL-SBA-15 (Pt/Co 1:3) with a COL selectivity of 98.2%. The catalyst was very stable, with no significant decrease in activity at the fifth recycling run. This work highlights the effect of Co addition on the formation of Pt–Co alloys and their compositions prepared via chemical reduction and provides an understanding of CAL activation on the nanoparticles with different surface compositions. [ABSTRACT FROM AUTHOR]

Exploring the surface organometallic chemistry on silica of highly electrophilic yttrium complexes is a relatively uncommon endeavor, particularly when focusing on tris‐alkyl complexes characterized by Y−C σ‐alkyl bonds. A drawback with this class of complexes once grafted on silica, is the frequent occurrence of alkyl transfer by ring opening of siloxane groups, resulting in a mixture of species. Herein, we employed a more stable homoleptic yttrium allyl complex bearing bulky η3‐1,3‐bis(trimethylsilyl)allyl ligand to limit this transfer reaction. This strategy has been validated by comparing the reactivity between [Y{ η3‐1,3‐C3H3(SiMe3)2}3] and [Y(o‐CH2PhNMe2)3] with SiO2–700, where the undesired alkyl transfer reaction occurred for [Y(o‐CH2PhNMe2)3] leading to a bipodal [(≡SiO)2Y(o‐CH2PhNMe2)] as major surface species, 2, while [Y{ η 3‐1,3‐C3H3(SiMe3)2}3] resulted selectively in a monopodal species, [(≡SiO)Y{η3‐1,3‐C3H3(SiMe3)2}2], 1. The materials obtained were characterized by DRIFT, solid state NMR, mass balance analysis and EXAFS. Catalyst 1 showed high activity compared to 2 in ethylene polymerization. The catalytic performance of this neutral catalyst 1 was extended to pre‐industrial scale in the presence of hydrogen and 1‐hexene. An unprecedented activity, up to 7400 gPE gcat−1 h−1 was obtained even with very low concentration of scavenger AliBu3 (TIBA/Y=1.2). The obtained HDPE exhibited desired spherical particle morphology with broad molar mass distribution. [ABSTRACT FROM AUTHOR]

Many chemical reactions are accompanied by concerted phenomena, such as variance transition, structural changes, and particle formation. Various measurement techniques are employed to understand the whole picture of such concerted phenomena. A combination of small‐angle X‐ray scattering (SAXS), X‐ray diffraction (XRD), and X‐ray absorption fine structure (XAFS) is useful for studying concerted phenomena that occur, for example, inside rechargeable batteries. This combination can cover large lengths from 1 Å to several hundred nm. Operando measurements using this combination of methods can follow reactions during the charging and discharging of a rechargeable battery in a single experimental run. Fixed‐exit optics enable irradiation at the same point in a wide energy range. By employing 2D detectors for XRD and SAXS and using a quick XAFS technique, one can make the interval of each measurement sufficiently short to track various phenomena during charging and discharging. Here, an application of the system for alternating SAXS/XRD/XAFS measurements constructed in BL28XU, SPring‐8, Japan to the study of rechargeable batteries, is presented. [ABSTRACT FROM AUTHOR]

This work presents a new and facile route for the preparation of iron oxide-based catalysts supported on alumina, which enables the targeted synthesis of catalysts with an increased amount of isolated tetrahedrally coordinated iron centers compared to a conventional impregnation procedure, and therefore leads to an increase in activity for CO oxidation reaction. By a multi-step impregnation–calcination protocol, the catalysts were synthesized with iron loadings of between 1 and 10 wt%, and their catalytic activity was then compared with a 10 wt% loaded catalyst prepared by conventional single impregnation. With a loading of 8 wt%, the presented catalysts showed an improved catalytic activity regarding light-off and full conversion temperatures compared to this reference. Through the application of several analytical methods (PXRD, PDF, DRUVS, SEM, XAFS), the improved catalytic activity can be correlated with an increased amount of isolated iron centers and a significantly reduced fraction of agglomerates or particles. [ABSTRACT FROM AUTHOR]

Electrosynthesis coupled hydrogen production (ESHP) mostly involves catalyst reconstruction in aqueous phase, but accurately identifying and controlling the process is still a challenge. Herein, we modulated the electronic structure and exposed unsaturated sites of metal–organic frameworks (MOFs) via ligand defect to promote the reconstruction of catalyst for azo electrosynthesis (ESA) coupled with hydrogen production overall reaction. The monolayer Ni‐MOFs achieved 89.8 % Faraday efficiency and 90.8 % selectivity for the electrooxidation of 1‐methyl‐1H‐pyrazol‐3‐amine (Pyr−NH2) to azo, and an 18.5‐fold increase in H2 production compared to overall water splitting. Operando X‐ray absorption fine spectroscopy (XAFS) and various in situ spectroscopy confirm that the ligand defect promotes the potential dependent dynamic reconstruction of Ni(OH)2 and NiOOH, and the reabsorption of ligand significantly lowers the energy barrier of rate‐determining step (*Pyr−NH to *Pyr−N). This work provides theoretical guidance for modulation of electrocatalyst reconstruction to achieve highly selective ESHP. [ABSTRACT FROM AUTHOR]

Analytical techniques for elemental analysis in the soil-plant system have significance importance, especially emerging techniques such as synchrotron radiation (SR). Improved techniques allow samples to be examined in a non-invasive manner at high speed and resolution, resulting in better sample data. By applying various analytical techniques based on SR, it is possible to gather different information about the structure of the studied samples. In mining ecology, such techniques are widely used in assessing heavy metal-polluted sites, i.e., overburden dumps and areas around operating and mothballed mines. The present review elaborated insights into different analytical techniques for applying SR in plant-soil samples. The review also compared traditional research techniques with SR-based emerging and improved techniques. The need to use SR techniques for the complex diagnostics of sample structures to study their elemental and phase composition is substantiated. Using an integrated approach with SR, we can study the dynamics and speciation of HMs with carrier phases and uncover the mechanisms underlying the interactions between the adsorption centers of minerals, organic components, and heavy metals. It also improves the efficiency and accuracy of analysis and broadens the range of information obtained, which could lead to a more precise analysis of samples.

The main regularities of pollutant distribution through the soil profile were established based on the analysis of the content of 15 priority PAHs in 29 soil sections of different soil types located in the coastal zone of the Lower Don and Taganrog Bay with different anthropogenic loads. It was shown that the total content of PAHs in the 0-20 cm layer of soils of coastal territories varies from 172 µg kg-1 to 16006 µg kg-1. In addition, according to the total pollution indicator, (Zc) determines the level of soil pollution, which varies from "not polluted" to "extremely polluted". The influence of pollution sources falls on the 0-20 cm layer of soils of different types and is especially pronounced for subordinate landscapes. With increasing sampling depth, the total PAH content decreases with the redistribution of individual compounds of the PAH group towards the dominance of low molecular weight and 4-ring compounds in the composition of the sum of 15 PAHs and depends largely on the content of organic matter and soil pH. Based on the cluster analysis results, the main factor determining the profile distribution of PAHs is the type of pollutant origin source and its intensity.

The main regularities of pollutant distribution through the soil profile were established based on the analysis of the content of 15 priority PAHs in 29 soil sections of different soil types located in the coastal zone of the Lower Don and Taganrog Bay with different anthropogenic loads. It was shown that the total content of PAHs in the 0-20 cm layer of soils of coastal territories varies from 172 μg kg-1 to 16006 μg kg-1. In addition, according to the total pollution indicator, (Zc) determines the level of soil pollution, which varies from "not polluted" to "extremely polluted". The influence of pollution sources falls on the 0-20 cm layer of soils of different types and is especially pronounced for subordinate landscapes. With increasing sampling depth, the total PAH content decreases with the redistribution of individual compounds of the PAH group towards the dominance of low molecular weight and 4-ring compounds in the composition of the sum of 15 PAHs and depends largely on the content of organic matter and soil pH. Based on the cluster analysis results, the main factor determining the profile distribution of PAHs is the type of pollutant origin source and its intensity. [ABSTRACT FROM AUTHOR]

Analytical techniques for elemental analysis in the soil-plant system have significance importance, especially emerging techniques such as synchrotron radiation (SR). Improved techniques allow samples to be examined in a non-invasive manner at high speed and resolution, resulting in better sample data. By applying various analytical techniques based on SR, it is possible to gather different information about the structure of the studied samples. In mining ecology, such techniques are widely used in assessing heavy metal-polluted sites, i.e., overburden dumps and areas around operating and mothballed mines. The present review elaborated insights into different analytical techniques for applying SR in plant-soil samples. The review also compared traditional research techniques with SR-based emerging and improved techniques. The need to use SR techniques for the complex diagnostics of sample structures to study their elemental and phase composition is substantiated. Using an integrated approach with SR, we can study the dynamics and speciation of HMs with carrier phases and uncover the mechanisms underlying the interactions between the adsorption centers of minerals, organic components, and heavy metals. It also improves the efficiency and accuracy of analysis and broadens the range of information obtained, which could lead to a more precise analysis of samples. [ABSTRACT FROM AUTHOR]

Small metal oligomers have gained significant attention due to their exceptional optoelectronic properties and versatile applications, ranging from sensors to imaging and catalysis. However, the need for matrices (silica, zeolites, or metal‐organic frameworks) to prevent aggregation into larger metallic particles reduces their potential applicability in light‐emitting devices (LEDs) due to their poor electrical properties. To address this issue, a novel semiconductor stabilizer, titanosilicate, is proposed as an innovative solution for Ag‐based luminescent materials. These results show that titanosilicate, characterized by high thermochemical stability and well‐defined semiconducting properties, is an ideal scaffold for Ag‐luminescent species. Optical spectroscopic techniques reveal that Ag‐titanosilicates feature an orange fluorescence with a photoluminescence quantum yield reaching 20%. In contrast, a combination of X‐ray diffraction, TEM, and XEOL‐X‐ray absorption spectroscopic techniques show that, unlike zeolites, the luminescent species consist of single Ag atoms. The electroluminescent properties of the proposed Ag‐titanosilicate are further investigated within a conventional LED architecture by using the new material as an emissive layer. The developed proof‐of‐concept LED exhibits a significant improvement of the ZEOLEDs, where a smaller low turn‐on voltage of 2 V (enabling energy‐efficient operation) and high color rendering index of 80 introduces exciting prospects for developing advanced Ag‐LED phosphors. [ABSTRACT FROM AUTHOR]

Primary water stress corrosion cracking (PWSCC) of Alloy 600 remains an important degradation phenomenon in PWRs. In particular, the susceptibility to the PWSCC initiation at 290°C is of recent interest because that is one of the typical temperatures of the primary water in contact with Alloy 600 which remains in PWRs. In this paper, oxide film formed on Alloy 600 in simulated primary water at 290°C was analyzed by X-ray absorption fine structure (XAFS) measurements at the Fe K-edge. For the preparation of the oxide film, Alloy 600 was immersed in simulated primary water with dissolved hydrogen (DH) concentration of 5 or 30 ml/kg-H2O. The near edge region of the XAFS suggested that the oxide film for 5 ml/kg-H2O DH had a larger Fe3+/Fe2+ ratio than for 30 ml/kg-H2O DH. Additionally, the extended region of the XAFS revealed that Fe3+ mainly occupied the octahedral site of the spinel oxide. Previous reports indicate that an Fe3+-rich spinel oxide is less defective and protective against PWSCC initiation. Therefore, our results suggest that the lower DH concentration (5 ml/kg-H2O) could potentially mitigate the susceptibility of Alloy 600 to the PWSCC initiation at 290°C. [ABSTRACT FROM AUTHOR]

Abstract The valence state and concentration of metallic pollutants are important factors contributing to the health effects of respirable particulate matter (PM); however, they have not been well studied. In this study, coarse and fine powder samples of atmospheric PM were collected using a cyclone system at Kanagawa (KO), Saitama (SA), and Fukuoka (FU) in Japan in 2017. Energy dispersive X-ray fluorescence spectroscopy (EDXRF) was used to measure the concentrations of nine metallic elements (Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Pb), and X-ray absorption fine structure (XAFS) spectroscopy was used to analyze the valence states of target elements (Cr, Mn, Fe, Cu, and Zn). The EDXRF results indicated that the average contents of Fe, Ti, and Zn were much higher than those of the other six elements in all samples. The XAFS results showed that the major valence states of the elements were Cr(III), Mn(II), Fe(III), Cu(II), and Zn(II). The percentages of Mn(IV), Fe(II), and Cu(0) were higher in KO and SA samples than in FU samples. Mn(0) and Zn(0) were detected in some samples only, and Cu(I) was not detected in any samples. Correlation analysis, principal component analysis, and cluster analysis were performed on the EDXRF and XAFS data of the target elements. The source identification results showed that the sources of metal contaminants in the samples varied considerably between sampling sites and depended on the industrial structure and geographical location of the sampling area. Our findings on the different valence states of the elements may be important for determining the toxicity of PM at different locations.

Herein, the crystallization behavior of a Li2O–Al2O3–SiO2 (LAS) glass system with the addition of ZrO2 and SnO2 as nucleating agents was investigated using X‐ray diffraction, differential scanning calorimetry, four‐dimensional scanning transmission electron microscopy, and X‐ray absorption fine‐structure measurements. At lower heat‐treatment temperatures, the addition of ZrO2 and SnO2 afforded a ZrSnO4 solid solution (SS), whereas at higher heat‐treatment temperatures, the ZrSnO4 SS decomposed, affording tetragonal ZrO2 and tetragonal SnO2. LAS‐based crystalline phases, such as β‐quartz and β‐spodumene phases SS, were formed after the formation of the ZrSnO4 SS. ZrSnO4 SS particles a few nanometers in size were present in contact with the β‐quartz SS particles a few dozen nanometers in size. This suggests that the ZrSnO4 SS served as a crystal nucleus for the β‐quartz SS, promoting its growth. [ABSTRACT FROM AUTHOR]

Single-phase, nanosized La0.7Ca0.3Mn1−xNixO3 (x = 0, 0.02, 0.07, 0.1) manganites were synthesized via the autocombustion route. Information on the local geometric structure and the charge state of the Mn ions in the nanosized samples was gleaned from extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) data analysis, respectively. The experimental absorption spectra were recorded at room temperature at the K-edge of the Mn-ions. Analysis of the normalized XANES spectra showed that the Mn formal valence remained practically unchanged upon Ni2+ doping. Nevertheless, the observed broadening of the ruling absorption edge suggested that the repulsive nearest-neighbor potential, stemming from the shortening of the distances of Mn to the nearest-neighbor oxygen atoms (Mn–O bonds) in the coordination shell, was slightly modified. The values of the Mn–O distances were obtained from the Fourier transformed EXAFS spectra. A slight but sizeable decrease in the value of the Mn–O bond distances was verified, which pointed to a slight variation in the Mn3+/Mn4+ ratio sparked by the Ni2+ doping. Here, a generation of more Mn4+ ions with smaller radius (0.53 Å) was expected. The obtained Mn–O distances were compared with those resulting from the Rietveld refinement of the X-ray powder diffraction data. The variation of the 〈Mn–O–Mn〉 bond angle with Ni2+ doping was also determined from the analysis of the X-ray diffraction patterns, which allowed visualizing the small distortion of the MnO6 octahedra on substitution of Mn with Ni2+. [ABSTRACT FROM AUTHOR]

The influence of Mn substitution on the iron lattice sites in LiFeO2 material was investigated with respect to the electronic, crystalline, and electrochemical properties of the material, using the LiFe1−xMnxO2 (x = 0.0, 0.05, and 0.10) series. The electronic structure study was conducted with the acquisition of x-ray absorption fine structure spectroscopy data, while the crystal structure properties of the studied materials were investigated using x-ray diffraction patterns. The data collected for the ionic conductivity properties of the samples by electrochemical impedance spectroscopy under increasing temperature conditions around and above room temperature aided the crystal and electronic structure studies on cathode materials. Furthermore, studies were conducted with the addition of CrFe2O4 material in varying molar concentrations into LiFeO2 material, as CrFe2O4 is known to have thermoelectric properties well above the room temperature of 400 K (127°C). Encouraging results for next-generation battery cathodes were obtained. [ABSTRACT FROM AUTHOR]

We present the conceptual design of a universal materials-research beamline based on the undulator of a fourth-generation synchrotron-radiation source. The distinctive feature of the beamline is its capability to work with both spectrally narrow (ΔE/E ~ 10–4) and relatively broad, high-intensity radiation beams (5 × 10–2). The optical scheme enables rapid switching between diffraction, radiographic, and spectroscopic experimental methods while keeping the beam's position fixed on the test sample and varying the spot size of the radiation from 100 nm to 1 mm. [ABSTRACT FROM AUTHOR]

For the application of CO2 as an energy storage material, a H2 storage system has been proposed based on the interconversion of CO2 and formic acid (or formate). However, energy losses are inevitable in the conversion of electrical energy to H2 as chemical energy (≈70 % electrical efficiency) and H2 to electrical energy (≈40 % electrical efficiency). To overcome these significant energy losses, we developed a system based on the interconversion of CO2 and formate for the direct storage and generation of electricity. In this paper, we report an aqueous redox flow battery system using homogeneous Ir catalysts with CO2‐formate redox pair. The system exhibited a maximum discharge capacity of 10.5 mAh (1.5 Ah L−1), capacity decay of 0.2 % per cycle, and total turnover number of 2550 after 50 cycles. During charging‐discharging, in situ fluorescence X‐ray absorption fine structure spectroscopy based on an online setup indicated that the active species was in a high valence state of IrIV. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of Pd/Ni modification on the photocatalytic hydrogen production performance of SrTiO3 (STO). STO catalysts were synthesized using a hydrothermal method, and Pd/Ni modification was applied on the surface of STO through chemical deposition. Experimental results demonstrate that the hydrogen evolution rate of Pd/Ni-modified STO (Pd/Ni-STO) reaches 2232.14 μ mol g−1 h−1. X-ray absorption fine structure spectroscopy analysis reveals substitutional doping of Ni with Ti and coordination of Pd with surface O. X-ray photoelectron spectroscopy analysis indicates the introduction of oxygen vacancies due to Pd/Ni doping. Density functional theory calculations suggest that Ni doping activates neighboring Ti atoms, leading to the formation of bimetallic catalytic sites composed of oxygen vacancies and Ti atoms, greatly enhancing the photocatalytic hydrogen evolution performance. This study not only provides an effective catalyst for photocatalytic applications but also offers insights into the underlying mechanism, which may stimulate the development of metal-doped catalytic materials and have implications for a range of other applications. [ABSTRACT FROM AUTHOR]

This work presents a new and facile route for the preparation of iron oxide-based catalysts supported on alumina, which enables the targeted synthesis of catalysts with an increased amount of isolated tetrahedrally coordinated iron centers compared to a conventional impregnation procedure, and therefore leads to an increase in activity for CO oxidation reaction. By a multi-step impregnation–calcination protocol, the catalysts were synthesized with iron loadings of between 1 and 10 wt%, and their catalytic activity was then compared with a 10 wt% loaded catalyst prepared by conventional single impregnation. With a loading of 8 wt%, the presented catalysts showed an improved catalytic activity regarding light-off and full conversion temperatures compared to this reference. Through the application of several analytical methods (PXRD, PDF, DRUVS, SEM, XAFS), the improved catalytic activity can be correlated with an increased amount of isolated iron centers and a significantly reduced fraction of agglomerates or particles.

Active sites in Mo-based hydrotreating catalysts are produced by sulfidation. To achieve insights that may enable optimization of the catalysts, this process should be studied in situ. Herein we present a comparative XAFS study where the in situ sulfidation of Mo/δ-Al2O3 and Ni/δ-Al2O3 is compared to that of δ-Al2O3 supported NiMo catalysts with different NiMo ratios. The study also covers the comparison of sulfidation of Ni and Mo using different oxide supports as well as the sulfidation conditions applied in the reactor. The XAFS spectra confirms the oxide phase for all catalysts at the beginning of the sulfidation reaction and their conversion to a sulfidized phase is followed with in situ measurements. Furthermore, it is found that the monometallic catalysts are less readily sulfidized than bimetallic ones, indicating the importance of Ni-Mo interactions for catalyst activation. Mo K-edge XAFS spectra did not show any difference related to the support of the catalyst or the pressure applied during the reaction. Ni K-edge XAFS spectra, however, show a more complete sulfidation of the Ni species in the catalyst when SiO2 is used as a support as compared to the Al2O3. Nevertheless, it is believed that stronger interactions with Al2O3 support prevent sintering of the catalyst which leads to its stabilization. The results contribute to a better understanding of how different parameters affect the formation of the active phase of the NiMo catalysts used in the production of biofuel. [ABSTRACT FROM AUTHOR]

In this paper, a relationship between the structure and the electrical properties of a nanocrystalline composite ceramics xNa2O·(100 − x)V2O5 with 'x' of 5, 15, 25, 35, and 45 mol%, abbreviated as xNV, was investigated by X-ray diffractometry (XRD), X-ray absorption spectroscopy (XAS), Cyclic Voltammetry (CV), Electrochemical impedance spectroscopy (EIS), and cathode active performance in Na-ion battery (SIB). For the expected sodium vanadium bronzes (NaxV2O5) precipitation, the preparation of xNV was performed by keeping the system in the molten state at 1200 °C for one hour, followed by a temperature decrease in the electric furnace to room temperature at a cooling rate of 10 °C min−1. XRD patterns of the 15NV ceramic exhibited the formation of Na0.33V2O5 and NaV3O8 crystalline phases. Moreover, the V K-edge XANES showed that the absorption edge energy of ceramics 15NV recorded at 5479 eV is smaller than that of V2O5 at 5481 eV, evidently indicating a partial reduction from V5+ to V4+ due to the precipitation of Na0.33V2O5. In the cyclic voltammetry, reduction peaks of 15NV were observed at 1.12, 1.78 V, and 2.69 V, while the oxidation peak showed up only at 2.36 V. The values of the reduction peaks were related to the NaV3O8 crystalline phase. Moreover, the diffusion coefficient of Na+ (DNa+) gradually decreased from 8.28 × 10−11 cm2 s−1 to 1.23 × 10−12 cm2 s−1 with increasing Na2O content (x) from 5 to 45 mol%. In the evaluation of the active cathode performance of xNV in SIB, ceramics 15NV showed the highest discharge capacity 203 mAh g−1 at a current rate of 50 mA g−1. In the wider voltage range from 0.8 to 3.6 V, the capacity retention was maintained at 50% after 30 cycles, while it was significantly improved to 90% in the narrower voltage range from 1.8 to 4.0 V, although the initial capacity decreased to 56 mAh g−1. It is concluded that the precipitation of the Na0.33V2O5 phase improved the structural and electrical properties of 15NV, which provides a high capacity for the Na-ion battery when incorporated as a cathode active material. [ABSTRACT FROM AUTHOR]

Asymmetry, such as non-centrosymmetry in the crystal or chiral structure and local symmetry breaking, plays an important role in the discovery of new phenomena. The honeycomb structure is an example of an asymmetric structure. Ce 2 Pt 6 Al 15 is a candidate for a frustrated system with honeycomb Ce-layers, which have been reported to show near the quantum critical point. However, the ground state of Ce 2 Pt 6 Al 15 depends on the sample, and analysis of the crystal structure is difficult due to the presence of stacking disorder. We synthesized polycrystalline Ce 2 Pt 6 Al 15 using arc melting method (AM-Ce 2 Pt 6 Al 15 ) and single-crystalline Ce 2 Pt 6 Al 15 using flux method (F-Ce 2 Pt 6 Al 15 ). The prepared samples were characterized by electron probe micro-analysis (EPMA), single and powder X-ray diffraction methods, measured magnetic properties and X-ray absorption spectroscopy (XAS). The composition ratio of AM-Ce 2 Pt 6 Al 15 was stoichiometric, although it contained a small amount (i.e., a few percent) of the impurity Ce 2 Pt 9 Al 16 . Meanwhile, the composition ratio of F-Ce 2 Pt 6 Al 15 deviated from stoichiometry. The X-ray absorption fine structure (XAFS) spectrum of AM-Ce 2 Pt 6 Al 15 at the Ce L 3 -edge was similar to that of CeF 3 , which possesses the Ce 3 + configuration, indicating that the valence of Ce in Ce 2 Pt 6 Al 15 is trivalent; this result is consistent with that for the magnetic susceptibility. To determine the precise structure, we analyzed the extended X-ray absorption fine structure (EXAFS) spectra of Ce L 3 - and Pt L 3 -edges for Ce 2 Pt 6 Al 15 , and found that the EXAFS spectra of Ce 2 Pt 6 Al 15 can be explained not as a hexagonal Sc 0.6 Fe 2 Si 4.9 -type structure but, instead, as an orthorhombic structure with honeycomb structure. [ABSTRACT FROM AUTHOR]

Extensive research has been conducted on platinum nanoparticles or clusters supported on zeolite for various catalytic applications, primarily due to the well-defined structure contained within the pore. The preparation and characterization of these particles have been thoroughly examined using advanced techniques such as X-ray absorption fine structures (XAFSs), both in situ and ex situ. In this study, we employed the Wavelet method to analyze the structure of platinum nanoparticles encapsulated within the supercage of a Y zeolite, where XAFS data were collected over a temperature range of 100 K to 423 K, both with and without hydrogen. The adsorption of hydrogen caused a relaxation in the structure of the platinum nanoparticles, thus leading to a decrease in the Pt–Pt distance and resulting in a lower Debye–Waller factor compared to bare nanoparticles. This structural change induced by hydrogen chemisorption aligns with the findings of the density functional theory (DFT) calculations for Pt13 nanoparticles located in the supercage. The relaxation of the structure results in charge redistribution, thereby ultimately generating atomic hydrogen with a partial negative charge, which is crucial for catalytic processes. [ABSTRACT FROM AUTHOR]

This study investigated the relationship between the solubility and the chemical speciation of plant nutritional elements (K, Ca, and Si) in wood ash treated with a dilute solution of sulfuric acid or phosphoric acid. The diluted acid solutions were added to fly ash (FA) collected from a power plant, and the untreated and acid-treated FAs were analyzed for their contents of K, Ca, and Si. The crystalline phases of the untreated and acid-treated FAs were identified using X-ray diffraction (XRD), and the Si species were determined using X-ray absorption near-edge structure (XANES) spectroscopy. Sulfuric acid and phosphoric acid treatments did not affect the solubility of K in FA. Water soluble and citrate soluble K in FA were decreased by the addition of these acids. The water soluble Ca content in FA treated with phosphoric acid did not show a significant change compared to that in the untreated FA, but it increased up to 65 times in FA treated with sulfuric acid. It is suggested that CaCO3, which was the main Ca species in the untreated FA, was transformed into syngenite and gypsum by the sulfuric acid treatment. Hydrochloric acid soluble Si in the acid-treated FA decreased compared to that in the untreated FA. In contrast, the NaOH-soluble Si fraction, a method for selectively extracting silica gel, increased especially in the phosphoric acid-treated FA. The results of XANES analysis showed that the FA samples treated with 10–30% sulfuric acid or 10–30% phosphoric acid had a lower degree of Si polymerization than the untreated FA, which corresponded generally to the increased Si solubility in FAs. However, FA treated with 30% sulfuric acid had lower soluble Si despite a lower degree of polymerization than FA, which was attributed to a lower pH. These results suggest that the change in solubility of Si in the acid-treated FA was influenced by the degree of polymerization and the decrease in pH. From the viewpoint of a fertilizer use of FA, sulfuric acid-treated ash, which consists of both water soluble Ca and citrate soluble Ca, is suitable for Ca fertilizer, and phosphoric acid-treated ash, which has high NaOH-soluble Si, is suitable for Si fertilizer [ABSTRACT FROM AUTHOR]

The feasibility of X-ray absorption fine-structure (XAFS) experiments of ultra-dilute metalloproteins under in vivo conditions (T = 300 K, pH = 7) at the BL-9 bending-magnet beamline (Indus-2) is reported, using as an example analogous synthetic Zn (0.1 mM) M1dr solution. The (Zn K-edge) XAFS of M1dr solution was measured with a four-element silicon drift detector. The first-shell fit was tested and found to be robust against statistical noise, generating reliable nearest-neighbor bond results. The results are found to be invariant between physiological and non-physiological conditions, which confirms the robust coordination chemistry of Zn with important biological implications. The scope of improving spectral quality for accommodation of higher-shell analysis is addressed.

In the pyro-reprocessing of spent nuclear fuel, salt bath is normally used in several times, but at final moment, spent salt containing small amount of chloride nuclear fuel material is generated. In terms of managing nuclear fuel materials, it is desirable that the nuclear fuel materials should be recovered from the spent salt. We are proposing methods for recovering nuclear fuel materials using precipitation by oxide addition and distillation for reducing pressure techniques. In this study, we have focused on the behavior of manganese(II), which is one of the radioactivated products. As a result of experiments and thermodynamic simulation, it was found that manganese(II) is likely to be entrained in nuclear fuel materials. Therefore, it is necessary to add a step to separate manganese(II) from nuclear fuel materials.

An investigation of temperature-dependent ionic activity of a representative sodium oxide material was carried out in the current research work due to the known importance of heat challenges in the battery development process. To assess the heat effects on the ionic conductivity capabilities, the electrochemical, electronic, and crystal structure properties of β-NaFeO2 and β-NaFeO2:Bi2Te3 composite materials were examined. The ionic conductivity of samples was slightly decreased by increasing the temperature, especially above 50–70°C. In contrast, better results were achieved for the β-NaFeO2:Bi2Te3 composite material than the parent β-NaFeO2 material as an indicator of the impacts of thermoelectric properties. At comparable temperatures, x-ray absorption (XAS) and x-ray absorption fine structure (XAFS) spectroscopic data were collected and processed to demonstrate the physical background influence of the increase in temperature on the atoms of the materials. It was found that the sodium atoms were the greatest contributors to the ionic conductivity loss at an increasing temperature among the materials. By separating from the spinel structure Fe–O ligand, sodium atoms increased the ionic capacitance by raising the temperature with a worse ionic conductivity. However, studies on the β-NaFeO2:Bi2Te3 composite material revealed a better ionic conductivity change than the β-NaFeO2 material with increasing temperature. This achievement was very clearly highlighted, particularly at the best working temperatures of Bi2Te3 material with a mechanism of absorbing waste heat and emitting free electrons. Additionally, the inactivity of β-NaFeO2 material could be determined by the instability of Na sites, which worsens with the increase in heat. [ABSTRACT FROM AUTHOR]

Phosphorus (P) recovered from wastewater as struvite (MgNH4PO4·6H2O) can meet high P demands in the agricultural sector by reuse as a P fertiliser. Heavy metals are prevalent in wastewaters and are common fertiliser contaminants, therefore struvite as a sorbent for metals requires evaluation. Struvite sorption experiments were conducted in model solutions with cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) at 1–5 μM concentrations from pH 7–10. The struvite metal loading increased with dissolved metal concentration and pH, ranging from 2 to 493 mg kg−1. Highest loadings were observed for 5 μM Pb, which exceeded the 120 mg kg−1 European Union (EU) struvite fertiliser limit at all pH values. At 5 μM concentrations, Ni and Cd loadings exceeded EU limits of 100 mg kg−1 at pH 10, and 60 mg kg−1 at pH 8–10, respectively. In desorption experiments, 10–85% metal was released after resuspension in metal-free solutions, with a positive correlation between initial loading and amount desorbed. Distortions of the struvite phosphate band, by Fourier transformation infrared (FTIR) spectroscopy, indicated lowered symmetry of phosphate vibrations with metal sorption. X-ray absorption fine structure spectroscopy (XAFS) analysis of pH 9 solids indicated tetrahedral coordination for Cu and Zn, octahedral coordination for Co and Ni, and Pb in 9-fold coordination. Precipitation of Pb-phosphate minerals was a primary mechanism for Pb sorption. The results provide insight into metal contaminant sorption with struvite in wastewaters, and the potential for metal desorption after recovery. [ABSTRACT FROM AUTHOR]

Revealing the electrocatalytic microstructure is the basis for finding more efficient and stable electrode materials for clean energy conversion devices. However, there is still a lack of direct understanding of the phase transition process of the sample during heating, which makes the synthesis conditions of the catalyst often rely on experienced guidance. Herein, ZIF‐8@α‐Co(OH)2 core‐shell structure and uniformly coated α‐Co(OH)2 nanosheets on the surface of ZIF‐8 are synthesized. The effect of temperature on microstructure evolution is studied by in situ heating technique with high‐resolution transmission electron microscopy. Based on understanding the relationship between temperature, microstructure, and OER properties, a simple annealing synthesis strategy is designed effectively. During the annealing process, ZnO@CoO heterogeneous structure is formed at 400 °C, and the material reached a stable hydroxyl oxide structure after electrochemical cycle voltammetry in an alkaline solution. The OER performance test shows that the commercial IrO2 catalyst has comparable catalytic performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oil-dispersed CoWS 2 catalysts of 7–10 nm were prepared in situ in VR HCK. • CoWS 2 catalysts showed better activity and stability than Co 9 S 8 or WS 2. • Formation of Co-WS 2 phase was confirmed by the Co K-edge XANES analysis. The bimetallic CoWS 2 catalysts were prepared in situ during the slurry phase hydrocracking (HCK) of vacuum residue (VR) using W(CO) 6 and Co-octoate as oil soluble precursors to investigate the promotional effect of Co promoters on the dispersed WS 2 catalyst for the VR HCK. The morphologies and structural properties of dispersed catalysts were characterized by transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS). The bimetallic CoWS 2 catalyst was observed to form well-dispersed monolayers in the size range of 7–11 nm, which showed higher turn-over frequency values (TOF) and C 7 -asphaltene (C 7 -ASP) conversions than monometallic WS 2 or Co 9 S 8 catalysts in the VR HCK at 693 K and 10.0 MPa H 2. Moreover, the extended X-ray fine absorption structure spectroscopy (EXAFS) coupled with the density functional theory (DFT) calculations successfully verified the formation of the Co-W-S phase. [ABSTRACT FROM AUTHOR]

The most accurate measurements of the mass attenuation coefficient for metals at low temperature for the zinc K-edge from 9.5 keV to 11.5 keV at temperatures of 10 K, 50 K, 100 K and 150 K using the hybrid technique are reported. This is the first time transition metal X-ray absorption fine structure (XAFS) has been studied using the hybrid technique and at low temperatures. This is also the first hybrid-like experiment at the Australian Synchrotron. The measured transmission and fluorescence XAFS spectra are compared and benchmarked against each other with detailed systematic analyses. A recent method for modelling self-absorption in fluorescence has been adapted and applied to a solid sample. The XAFS spectra are analysed using eFEFFIT to provide a robust measurement of the evolution of nanostructure, including such properties as net thermal expansion and mean-square relative displacement. This work investigates crystal dynamics, nanostructural evolution and the results of using the Debye and Einstein models to determine atomic positions. Accuracies achieved, when compared with the literature, exceed those achieved by both relative and differential XAFS, and represent a state-of-the-art for future structural investigations. Bond length uncertainties are of the order of 20–40 fm.

A new quick-scanning extended X-ray absorption fine-structure (QEXAFS) system for in situ studies has been developed and tested on the general XAFS beamline at the Shanghai Synchrotron Radiation Facility. In the new system, an analog-to-digital converter (ADC) with 1 MHz sampling rate is used to acquire the detector data while one scaler is used to precisely calculate the scanning energy. Two external hardware trigger signals were adopted to synchronize the data collection of the ADC and the scaler. The software development platforms of the double-crystal monochromator control system and the new QEXAFS system have been unified with the Experimental Physics and Industrial Control System. By comparing the spectra acquired by the conventional step-by-step XAFS system with an energy range of 1200 eV at the 7.5um Cu foil K-edge, the new system demonstrates satisfactory signal-to-noise ratio and energy resolution. The previous shortcomings, including distortion of the spectrum and energy shift, have been overcome. The tests with different integration times indicated that appropriate parameters not only ensure good experimental results but also enhance the smoothness of the XAFS spectrum at high energy zones. The reliability of the new system has also been verified.

γ-Irradiation and synchrotron-radiation-based X-ray absorption fine-structure (XAFS) spectroscopy have been used to induce structure disorder through the interaction of γ-rays (200 kGy) with fabricated Mn-doped ZnO nanoparticles (NPs) and then to examine thoroughly the resultant structural change. The extracted electronic/fine XAFS structural parameters reflect a compositional and γ-irradiation co-dependence. The average crystal structure of samples prepared by the sol-gel method was investigated by X-ray diffraction (XRD). A detailed structural XRD data analysis was carried out by applying a Rietveld refinement using the MAUD program. XAFS spectra were collected at the Zn K-edge (9659 eV) in transmission mode and at the Mn K-edge (6539 eV) in fluorescence mode. Direct evidence of the solubility of Mn ions in the ZnO structure was demonstrated by fitting the extended-XAFS (EXAFS) signal. Near-edge XAFS (XANES) analysis provided the oxidation states of Zn and Mn ions through fingerprint XANES spectra of the sample along with those of standard compounds. Linear combination fitting showed that the most fit chemical forms of Zn and Mn in the samples are ZnO and MnO, respectively. The oxidation states of both Zn and Mn XAFS absorbers were confirmed from pre-edge fitting. The results of the magnetic measurements were explained in light of the average and electronic/local structural information obtained from XRD, XANES and EXAFS techniques. The magnetic properties of the samples translate into an induced change in the average crystal and electronic/local structures upon Mn concentration change and γ-irradiation. XRD confirmed the successful preparation of hexagonal Mn-doped ZnO NPs with a crystallite size in the range 33–41 nm. Both XRD and EXAFS analysis detected a minor amount of Mn3O4 as a secondary phase. XANES and EXAFS provided information exploring the outstanding potential of the utilized protocol for detecting precisely the presence of the secondary phase of Mn3O4, which changes with Mn content (x). Mean-square relative displacement (σ2) values extracted from the EXAFS fitting were found to grow for Zn–Zn/Mn paths demonstrating the substitution of Mn/Zn into Zn crystal sites. The EXAFS analysis explains the reasons behind the enhancement in the magnetic properties and shows that the Mn doping content at x = 0.05 produces the most local atomic disorder in ZnO NPs. There is a strong harmony among the XRD, XANES, EXAFS and magnetization behavior of the Mn-doped ZnO NPs. Maximum magnetization was acquired at an Mn content of 0.05. γ-Ray-irradiated Zn1–xMnxO NPs are recommended as optimized candidates for showing the diversity of the applications.

Ammonia has the advantages of being easy to liquefy, easy to store, and having a high hydrogen content of 17.3 wt%, which can be produced without COx through an ammonia decomposition using an appropriate catalyst. In this paper, a series of FeCr bimetallic oxide nanocatalysts with a uniform morphology and regulated composition were synthesized by the urea two-step hydrolysis method, which exhibited the high-performance decomposition of ammonia. The effects of different FeCr metal ratios on the catalyst particle size, morphology, and crystal phase were investigated. The Fe0.75Cr0.25 sample exhibited the highest catalytic activity, with an ammonia conversion of nearly 100% at 650 °C. The dual metal catalysts clearly outperformed the single metal samples in terms of their catalytic performance. Besides XRD, XPS, and SEM being used as the means of the conventional characterization, the local structural changes of the FeCr metal oxide catalysts in the catalytic ammonia decomposition were investigated by XAFS. It was determined that the Fe metal and FeNx of the bcc structure were the active species of the ammonia-decomposing catalyst. The addition of Cr successfully prevented the Fe from sintering at high temperatures, which is more favorable for the formation of stable metal nitrides, promoting the continuous decomposition of ammonia and improving the decomposition activity of the ammonia. This work reveals the internal relationship between the phase and structural changes and their catalytic activity, identifies the active catalytic phase, thus guiding the design and synthesis of catalysts for ammonia decomposition, and excavates the application value of transition-metal-based nanocomposites in industrial catalysis. [ABSTRACT FROM AUTHOR]

In the present study, the ability of a modified CaCl2 zeolite (Ca-Z) to both increase Se(IV) availability and restrict Se(VI) mobility in soils is examined. As it was resulted from batch experiments and verified by X-ray absorption fine structure (XAFS) and X-ray fluorescence (XRF) spectroscopies, higher amounts of both Se species adsorbed on Ca-Z compared to natural zeolite (Z-N) forming outer-sphere complexes while the oxidation state did not alter during agitation of samples. Thereafter, Ca-Z was incorporated in six Greek soils, divided into acid and alkaline, at a 20% (w/w) rate and a series of equilibrium batch experiments were performed with soils alone and soils-Ca-Z mixtures to investigate sorption and desorption processes and mechanisms. The acid soils, either treated with Ca-Z or not, adsorbed higher amounts of Se(IV) than alkaline ones, whereas soils alone did not adsorb Se(VI) but impressively high adsorption of Se(VI) occurred in the Ca-Z-treated soils. Desorption of Se(IV) was higher from the Ca-Z-treated soils and especially from the acid soils. Higher distribution coefficients of desorption than the distribution coefficients of sorption were observed, clearly pointing to a hysteresis mechanism. The experimental data fitted with Langmuir and Freundlich isotherms. In the presence of Ca-Z, the Langmuir qm values increased indicating higher Se(IV) retention while Langmuir bL values decreased suggesting lower bonding strength and higher Se(IV) mobility. Overall, treating the soils with Ca-Z increased Se(IV) adsorption and mobility whereas it provided sites for Se(VI) adsorption that did not exist in the studied soils. [ABSTRACT FROM AUTHOR]

The feasibility of X-ray absorption fine-structure (XAFS) experiments of ultradilute metalloproteins under in vivo conditions (T = 300 K, pH = 7) at the BL-9 bending-magnet beamline (Indus-2) is reported, using as an example analogous synthetic Zn (0.1 mM) M1dr solution. The (Zn K-edge) XAFS of M1dr solution was measured with a four-element silicon drift detector. The first-shell fit was tested and found to be robust against statistical noise, generating reliable nearest-neighbor bond results. The results are found to be invariant between physiological and non-physiological conditions, which confirms the robust coordination chemistry of Zn with important biological implications. The scope of improving spectral quality for accommodation of higher-shell analysis is addressed. [ABSTRACT FROM AUTHOR]

The influence of annealing temperature and deviation from stoichiometry on the incorporation of the Fe impurity into the A and B sites of the perovskite structure is studied using XAFS spectroscopy and X-ray diffraction. It is shown that at high annealing temperature about 30% of the iron atoms enter the A sites in SrTiO3. The obtained results agree with the results of first-principles calculations, according to which the Fe2+ ion at the A site exhibits strong off-centering (the displacement of ∼1 Å). The mechanism of magnetoelectric interaction for magnetic off-center ions is discussed. [ABSTRACT FROM AUTHOR]

This study investigated the cluster formation process in the early stages of 353K aging in Al-1.04 mass%Si0.55 mass%Mg alloys by means of soft X-ray absorption fine structure (XAFS) measurements and first-principles calculations. XAFS at the Si-K and Mg-K edges was carried out at the BL27SU beamline at SPring-8. To observe the structural changes in detail, an XAFS apparatus able to hold the sample at 353K in a vacuum chamber and cool it rapidly to suppress the progress of clustering was developed. Density functional theory (DFT) calculations were used to simulate the Si-K and Mg-K edge spectra for various cluster models. Based on the results, the cluster formation process in the early stages of aging at 353K was qualitatively clarified. Initially, MgVa (Va: vacancy) pairs and SiVa pairs were formed, then 2-MgVa clusters formed by bonding between MgVa pairs along (100); subsequently, L10 clusters were formed by Mg atoms ordered along (100), and then SiVapy clusters with Va adjacent to the first-nearest-neighbor atom of Si atoms and Si-py without adjacent Va were formed, in which MgVa pairs and SiVa pairs were individually united, respectively. Monolayer and multilayer structures then developed as aging proceeded, involving Mg and Si atoms ordered along (100), in which Mg and Si atoms were bonded. [ABSTRACT FROM AUTHOR]

Abstract Revealing the electrocatalytic microstructure is the basis for finding more efficient and stable electrode materials for clean energy conversion devices. However, there is still a lack of direct understanding of the phase transition process of the sample during heating, which makes the synthesis conditions of the catalyst often rely on experienced guidance. Herein, ZIF‐8@α‐Co(OH)2 core‐shell structure and uniformly coated α‐Co(OH)2 nanosheets on the surface of ZIF‐8 are synthesized. The effect of temperature on microstructure evolution is studied by in situ heating technique with high‐resolution transmission electron microscopy. Based on understanding the relationship between temperature, microstructure, and OER properties, a simple annealing synthesis strategy is designed effectively. During the annealing process, ZnO@CoO heterogeneous structure is formed at 400 °C, and the material reached a stable hydroxyl oxide structure after electrochemical cycle voltammetry in an alkaline solution. The OER performance test shows that the commercial IrO2 catalyst has comparable catalytic performance.

XAFS/XRF is a general-purpose absorption spectroscopy beamline at the Synchrotron-light for Experimental Science and Applications in the Middle East (SESAME), Jordan. Herein, its optical layout is presented along with its powerful capabilities in collecting absorption and fluorescence spectra within a wide energy range (4.7–30 keV). The beamline is equipped with a conventional fixed-exit double-crystal monochromator that allows the collection of an X-ray absorption spectrum within a few minutes in step-by-step mode. An on-the-fly scanning mode will be implemented shortly where the acquisition time will be reduced to less than a minute per scan. The full automation of the beamline allows performing successive measurements under different conditions. The different experimental setups and special features available to users are reported. Examples of XRF and XAFS measurements are presented, showing the performance of the beamline under different standard conditions.

Heavy metal contamination of soils has been a global environmental issue over the past decades, threatening food security and human health. Understanding the migration and transformation of heavy metals in soils is critical for restoring an impaired environment and developing sustainable agriculture, particularly in the face of global warming. However, little effort has been devoted to investigating the impact of elevated temperatures on the migration and distribution of exogenous heavy metals in soils. This study experimented with a 180-day incubation at 15 °C, 30 °C, and 45 °C with an arable soil (Alfisol) of Huang-Huai-Hai River Basin, China, which was initially spiked with copper (Cu). A comparison of the results revealed that the percentage of soil water-soluble Cu doubled at 45 °C compared with 15 °C. The percentage of protein-like substances in dissolved organic matter (DOM) was the highest at 45 °C, suggesting that proteinaceous components play a more significant role in controlling the dissolution of Cu into DOM. Moreover, by sequential extraction and micro-X-ray fluorescence (μ-XRF), Cu was facilitatively transformed from exchangeable, and specifically adsorbed fractions, to iron (Fe)/manganese (Mn) oxides bound species by 7.75%23.63% with the elevation of temperature from 15 °C to 45 °C. The conversion of Cu speciation is attributed to the significant release of organic carbon from Fe/Mn oxides, especially the Mn oxide components, which are available for Cu binding. The findings of this work will provide an in-depth understanding of the fate of Cu in soils, which is fundamental for the risk assessment and remediation of Cu-polluted soils in the Huang-Huai-Hai River Basin under the context of global warming.

The most accurate measurements of the mass attenuation coefficient for metals at low temperature for the zinc K-edge from 9.5 keV to 11.5 keV at temperatures of 10 K, 50 K, 100 K and 150 K using the hybrid technique are reported. This is the first time transition metal X-ray absorption fine structure (XAFS) has been studied using the hybrid technique and at low temperatures. This is also the first hybrid-like experiment at the Australian Synchrotron. The measured transmission and fluorescence XAFS spectra are compared and benchmarked against each other with detailed systematic analyses. A recent method for modelling self-absorption in fluorescence has been adapted and applied to a solid sample. The XAFS spectra are analysed using eFEFFIT to provide a robust measurement of the evolution of nanostructure, including such properties as net thermal expansion and mean-square relative displacement. This work investigates crystal dynamics, nanostructural evolution and the results of using the Debye and Einstein models to determine atomic positions. Accuracies achieved, when compared with the literature, exceed those achieved by both relative and differential XAFS, and represent a state-of-the-art for future structural investigations. Bond length uncertainties are of the order of 20-40 fm. [ABSTRACT FROM AUTHOR]

Copper complexes with 1,3-disubstituted thiourea derivatives, all containing 3-(trifluoromethyl)phenyl tail and 1-alkyl/halogen-phenyl substituent, were synthesized. The experimental spectroscopic studies and theoretical calculation revealed that two ligands coordinate to Cu(II) in a bidentate fashion via thiocarbonyl S and deprotonated N atoms of thiourea moiety. Such monomers are characteristic of alkylphenylthiourea complexes, whereas the formation of a sandwich-type dimer is observed for halogeno derivatives. For the first time, the structural identifications of CuN2S2-based complexes using experimental and theoretical X-ray absorption near edge structure are demonstrated. The dimeric halogeno derivatives showed higher antimicrobial activity in comparison with alkylphenylthiourea complexes. The Cu(II) complex of 1-(4-chloro-3-nitrophenyl)-3-[3-(trifluoromethyl)phenyl]thiourea was active against 19 strains of methicillin-resistant Staphylococci (MIC = 2 µg/mL). This derivative acted as a dual inhibitor of DNA gyrase and topoisomerase IV isolated from Staphylococcus aureus. Additionally, complexes of halogenphenylthiourea strongly inhibited the growth of mycobacteria isolated from tuberculosis patients, even fourfold stronger than the reference isoniazid. The complexes exerted weak to moderate antitumor activity (towards SW480, SW620, and PC3) being non-toxic towards normal HaCaT cells. [ABSTRACT FROM AUTHOR]

Multiferroic BiFeO3 and 10% La/Mn-doped BiFeO3 powder samples were synthesized by conventional hydrothermal method to study the substitution at different sites driven by structural transformation and magnetic property in BiFeO3. Room-temperature X-ray diffraction (XRD) patterns identified the rhombohedral R3c symmetry for all samples and further confirmed by the Bi-L3 edge and Fe-K edge X-ray absorption fine structure (XAFS) spectra. However, a nanoscale phase transition from R3c structure to orthorhombic symmetry was revealed by the La-L3 edge XAFS. In contrast, the Mn-doped BiFeO3 remained R3c crystal structure. Besides, the variation of magnetism due to A-site and B-site substitution in BiFeO3 was observed in the magnetic hysteresis loops. [ABSTRACT FROM AUTHOR]

Oxygen fugacity is an important but difficult parameter to constrain for primitive arc magmas. In this study, the partitioning behavior of Fe3+/Fe2+ between amphibole and glass synthesized in piston-cylinder and cold-seal apparatus experiments is developed as an oxybarometer, applicable to magmas ranging from basaltic to dacitic composition. The partitioning of Fe2+ is strongly dependent on melt polymerization; the relative compatibility of Fe2+ in amphibole decreases with increasing polymerization. The Fe2+/Mg distribution coefficient between amphibole and melt is a relatively constant value across all compositions and is, on average, 0.27. The amphibole oxybarometer is applied to amphibole in mafic enclaves, cumulates, and basaltic tephra erupted from Shiveluch volcano in Kamchatka with measured Fe3+/FeTotal. An average Fe3+/Fe2+ amphibole-glass distribution coeficient for basalt is used to convert the Fe3+/FeTotal of amphibole in samples from Shiveluch to magmatic oxygen fugacity relative to NNO. The fO2 of primitive melts at the volcano is approximately NNO+2 and is faithfully recorded in amphibole from an amphibole-rich cumulate and the basaltic tephra. Apparently, higher fO2 recorded by amphibole in mafic enclaves likely results from partial dehydrogenation of amphibole during residence in a shallow andesite storage region. We identify three pulses of mafic magma recharge within two weeks of, a month before, and two to three months before the eruption and find that, at each of these times, the host andesite was recharged by at least two magmas at varying stages of differentiation. Application of the amphibole oxybarometer not only gives insight into magmatic fO2 but also potentially details of shallow magmatic processes. [ABSTRACT FROM AUTHOR]

A new quick-scanning extended X-ray absorption fine-structure (QEXAFS) system for in situ studies has been developed and tested on the general XAFS beamline at the Shanghai Synchrotron Radiation Facility. In the new system, an analog-to-digital converter (ADC) with 1 MHz sampling rate is used to acquire the detector data while one scaler is used to precisely calculate the scanning energy. Two external hardware trigger signals were adopted to synchronize the data collection of the ADC and the scaler. The software development platforms of the double-crystal monochromator control system and the new QEXAFS system have been unified with the Experimental Physics and Industrial Control System. By comparing the spectra acquired by the conventional step-by-step XAFS system with an energy range of 1200 eV at the 7.5um Cu foil K-edge, the new system demonstrates satisfactory signal-to-noise ratio and energy resolution. The previous shortcomings, including distortion of the spectrum and energy shift, have been overcome. The tests with different integration times indicated that appropriate parameters not only ensure good experimental results but also enhance the smoothness of the XAFS spectrum at high energy zones. The reliability of the new system has also been verified. [ABSTRACT FROM AUTHOR]