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Strontium-90 is a radionuclide of concern that is mobile in soil and groundwater and is a threat to life. Activated hydrogel biopolymer composites were fabricated for strontium remediation from groundwater. Batch uptake demonstrated a maximal stontium uptake capacity of 109 mg g−1, much higher than unactivated hydrogel controls. Activation also more than doubled the decontamination factor at environmentally relevant concentrations. EXAFS was used to investigate the binding mechanism, revealing inner sphere complexation of strontium for the first time. Biopolymer composities synthesized for these studies are sustainable and cheap remediation materials that exhibit good strontium uptake and inner sphere binding.

Porous boron nitride (BN) displays promising properties for interfacial and bulk processes, e.g. molecular separation and storage, or (photo)catalysis. To maximise porous BN's potential in such applications, tuning and controlling its chemical and structural features is key. Functionalisation of porous BN with metal nanoparticle represents one possible route, albeit a hardly explored one. Metal–organic frameworks (MOFs) have been widely used as precursors to synthesise metal functionalised porous carbon-based materials, yet MOF-derived metal functionalised inorganic porous materials remain unexplored. Here, we hypothesise that MOFs could also serve as a platform to produce metal-functionalised porous BN. We have used a Cu-containing MOF, i.e. Cu/ZIF-8, as a precursor and successfully obtained porous BN functionalised with Cu nanoparticles (i.e. Cu/BN). While we have shown control of the Cu content, we have not yet demonstrated it for the nanoparticle size. The functionalisation has led to improved light harvesting and enhanced electron–hole separation, which have had a direct positive impact on the CO2 photoreduction activity (production formation rate 1.5 times higher than pristine BN and 12.5 times higher than g-C3N4). In addition, we have found that the metal in the MOF precursor impacts porous BN's purity. Unlike Cu/ZIF-8, a Co-containing ZIF-8 precursor led to porous C-BN (i.e. BN with a large amount of C in the structure). Overall, given the diversity of metals in MOFs, one could envision our approach as a method to produce a library of different metal functionalised porous BN samples.

Bis(pyrazol-1-yl)- and bis(3,5-dimethylpyrazol-1-yl)-acetates were conjugated with the 2-hydroxyethylester and 2-aminoethylamide derivatives of the antineoplastic drug lonidamine to prepare Cu(I) and Cu(II) complexes that might act through synergistic mechanisms of action due to the presence of lonidamine and copper in the same chemical entity. Synchrotron radiation-based complementary techniques [X-ray photorlectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS)] were used to characterize the electronic and molecular structures of the complexes and the local structure around the copper ion (XAFS) in selected complexes. All complexes showed significant antitumor activity, proving to be more effective than the reference drug cisplatin in a panel of human tumor cell lines, and were able to overcome oxaliplatin and multidrug resistance. Noticeably, these Cu complexes appeared much more effective than cisplatin against 3D spheroids of pancreatic PSN-1 cancer cells; among these, PPh3-containing Cu(I) complex 15 appeared to be the most promising derivative. Mechanistic studies revealed that 15 induced cancer cell death by means of an apoptosis-alternative cell death.

We report the ligand-exchange-induced transformation from an icosahedral Au25(SR)18 cluster (where SR = 2-phenylethanethiol (PET)) to a bitetrahedral Au22(SR)4(SR')14 cluster (where SR' = 4-tert-butylbenzenethiol (TBBT)). This partial exchange of the ligands was achieved by controlling the concentration of the incoming TBBT ligand. Being a bulky and aromatic ligand, TBBT can efficiently distort the atomic structure of the Au25PET18 cluster, resulting in Au22(PET)4(TBBT)14, which is highly stable and considered to be an intermediate with a bitetrahedral structure. Time-dependent mass spectrometry and optical spectroscopy revealed the dissociation of the parent cluster and gave a deep insight on the ligand-exchange mechanism. Theoretical calculations and extended X-ray absorption fine structure studies confirm the formation of the Au22 structure. Identifying the atomic structure of the intermediate species opens a new avenue to study the transformation of one cluster to another.

We investigate influence of oxygen migration in MgO/Co/MgO trilayer structure by varying Co and MgO layer thickness. To resolve Co/MgO interface structural and magnetic properties, we used near edge X-ray absorption spectra (XANES), X-ray absorption fine structure (XAFS) spectroscopy and Magneto-optical Kerr effect (MOKE) on MgO/Co/MgO trilayer structure. O K-edge XANES spectra show the variation in hybridization of Co 3d orbitals with neighboring O 2p orbitals as a function of Co layer thickness. Co L3 -edge XANES and Co K-edge XAFS results revealed the quantity of CoO formation as a function of Co layer thickness from discontinuous layer to continuous layer. Formation of cobalt oxide is mainly due to island formation of Co ≤ 10 nm layer and oxygen migration from MgO layer at interface via redox reaction to form Co O bonds. The oxygen migration is driven by imperfect stoichiometry of MgO at the Co/MgO interface. The formation of CoO layer influences the Co O orbital hybridization modifying in-plane magnetic anisotropy as a function of Co and MgO layer thickness. Higher coercivity (Hc) for lower thickness of Co layer confirms the formation of domain wall pinning. A model has been drawn to describe the interaction of Co layer with MgO layer at Co/MgO interface from discontinues to continuous region of Co thin film of magnetic tunnel junctions (MTJ)s, which may help to design high-performance spintronic devices.

We report the ligand-exchange-induced transformation from an

Lithium-rich transition-metal-oxide cathodes are among the most promising materials for next generation lithium-ion-batteries because they operate at high voltages and deliver high capacities. However, their cycle-life remains limited, and individual roles of the transition-metals are still not fully understood. Using bulk-sensitive X-ray absorption and emission spectroscopy on Li[Li0.2Ni0.16Mn0.56Co0.08]O2, we inspect the behavior of Mn, generally considered inert upon the electrochemical process. During the first charge Mn appears to be redox-active showing a partial transformation from high-spin Mn4+ to Mn3+ in both high and low spin configurations, where the latter is expected to favor reversible cycling. The Mn redox-state with cycling continues changing in opposition to the expected charge compensation and is correlated with Ni oxidation/reduction, also spatially. The findings suggest that strain induced on the Mn−O sublattice by Ni oxidation triggers Mn reduction. These results unravel the Mn role in controlling the electrochemistry of Li-rich cathodes., This work has been partially financed by the Spanish Ministry of Economy and Competitiveness, through the Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015- 0496). The HIU authors kindly acknowledge the basic funding of the Helmholtz Association.

Combining micro-X-ray absorption spectroscopy (μXAS) and micro-X-ray fluorescence spectroscopy (μXRF) is a promising approach for the investigation of complex multi-phase systems. In this work, we have employed this approach to investigate natural sphalerite, the most common form of Zinc Sulfide. Spatially resolved elemental distribution maps of common 3d metal atoms (Zn, Cu, Ni, Co, and Fe) are superimposed with chemical speciation and structural parameter maps in order to understand the sphaleriteore-formation process and metamorphosis. Chemical speciation and structural parameters have been obtained by analyzing the μXAS spectra collected in several representative points of the sample, after μXRF mapping. In the present case, this X-ray based approach has permitted to determine the spatial distribution of the Zn species in sphalerite. The presence of two main zincite and smithsonite inclusions has been established, with the latter located close to copper impurity center. Since copper is known to remarkably reduce the corrosion resistance of zinc, resulting in the formation of carbonate as the corrosion product, this implies a possible role of Cu in the growth of the carbonate inclusions. The results obtained highlight the efficiency of this method in univocally identifying the spatial distribution of phases in complex systems, thanks to the simultaneous access to complementary information.

XANES- and EXAFS-based analysis of the Ayurvedic Hg-based nano-drugRasasindurahas been performed to seek evidence of its non-toxicity.Rasasindurais determined to be composed of single-phase α-HgS nanoparticles (size ∼24 nm), free of Hg0or organic molecules; its structure is determined to be robust (0implies the absence of Hg-based toxicity and establishes that chemical form, rather than content of heavy metals, is the correct parameter for evaluating the toxicity in these drugs. The stable α-HgS form (strong Hg—S covalent bond and robust particle character) ensures the integrity of the drug during delivery and prevention of its reduction to Hg0within the human body. Further, these comparative studies establish that structural parameters (size dispersion, coordination configuration) are better controlled inRasasindura. This places the Ayurvedic synthesis method on par with contemporary techniques of nanoparticle synthesis.

We have studied the local structure of layered Nax(NH3)yMoSe2 system by Mo K-edge extended X-ray absorption fine structure (EXAFS) measurements performed as a function of temperature. We find that molecular intercalation in MoSe2 largely affects the Mo-Se network while Mo-Mo seems to sustain small changes. The Einstein temperature ( Θ E ) of Mo-Mo distance hardly changes ( ∼ 264 K) indicating that bond strength of this distance remains unaffected by intercalation. On the other hand, Mo-Se distance suffers a softening, revealed by the decrease of Θ E from ∼ 364 K to ∼ 350 K. The results indicate that Na+ ion transported by NH3 molecules may enter between the two MoSe-layers resulting reduced Se-Se coupling. Therefore, increased hybridization between Se 4p and Mo 4d orbitals due to inter-layer disorder is the likely reason of metallicity in intercalated MoSe2 and superconductivity at low temperature.

The synthesis, characterization and assessment of the antibacterial properties of hydrophilic silver nanoparticles (AgNPs) were investigated with the aim to probe their suitability for innovative applications in the field of nanobiotechnology. First, silver nanoparticles were synthetized and functionalized with two capping agents, namely 3-mercapto-1-propansulfonate (3MPS) and 1-β-thio-d-glucose (TG). The investigation of the structural and electronic properties of the nano-systems was carried out by means of X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS). XPS data provided information about the system stability and the interactions between the metallic surface and the organic ligands. In addition, XPS data allowed us to achieve a deep understanding of the influence of the thiols stoichiometric ratio on the electronic properties and stability of AgNPs. In order to shed light on the structural and electronic local properties at Ag atoms sites, XAS at Ag K-Edge was successfully applied; furthermore, the combination of Dynamic Light Scattering (DLS) and XAS results allowed determining AgNPs sizes, ranging between 3 and 13 nm. Finally, preliminary studies on the antibacterial properties of AgNPs showed promising results on four of six multidrug-resistant bacteria belonging to the ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter sp.).

In this work nanoclusters formed in a Pt/Ni/C multi-trilayer by the ion-irradiated method of synthesis are characterized. In particular, an attempt to understand the role of interfaces in the synthesis is made. With this objective, ion-irradiation-induced structural changes in a Pt/Ni/C multi-trilayer using X-ray absorption spectroscopy (at the NiK-edge) in conjunction with the X-ray standing-wave technique are investigated. The XANES analysis identifies chemical binding at pristine Ni/C and Ni/Pt interfaces, in contrast with physical adsorption at the Pt/C interface. The chemical nature of the interfaces determines their relative stability with respect to irradiation and controls the extent of metallic diffusion. The most interesting structural change, upon irradiation, is the disruption of the Pt/C interface and subsequent migration of Pt atoms towards pre-diffused Ni atoms within the C layer, leading to the formation of Ni-centered Ni–Pt bimetallic nanoclusters (with Ni:Pt = 60:40). These clusters are highly disordered beyond their nearest neighbor and find wide-scale applications as, for example, magnetic devicesetc. The implications of these findings on the design goals are discussed.

We have investigated the microscopic origin of temperature and magnetic-field actuated magnetization reversal in Cu0.73Mn0.77[Fe(CN)6].zH2O, using XMCD. Our results show a fair deviation from the mean-field-theory in the form of different ordering temperatures of Fe and Mn sublattices. A preferential sign reversal of Mn spin under magnetic field and different spin cant angles for the two sublattices have also been observed. An antiferromagnetic coupling between the Fe and Mn sublattices along with different ordering temperatures (sublattice decoupling) for these sublattices explain the temperature-dependent magnetization reversal. Whereas, Mn spin reversal alone (under external magnetic field) is responsible for the observed field-dependent magnetization reversal. The dissimilar magnetic behavior of Fe and Mn sublattices in this cubic 3d-orbital system has been understood by invoking disparity and competition among inter-sublattice magnetic control parameters, viz. magnetic Zeeman energy, exchange coupling constant and magnetic anisotropy constant. Our results have significant design implications for future magnetic switches, by optimizing the competition among these magnetic control parameters.

Magnetic compensation (zero-moment) has important advantage in spintronics as it does not generate any self stray magnetic field. The physics of magnetic compensation (at a well defined temperature Tcomp) is well understood in terms of competition and compensation between antiferromagnetically coupled magnetic moments of two rare earth ions. The different thermal evolution of the dissimilar rare earth moments can compensate each other at a particular temperature determined by the concentration of the dopant. We have observed, for the first ever time, "repeated" magnetic compensation in both polycrystalline and single crystals of Nd0.8Tb0.2Al2 (Tf1 ~ 86 K and Tf2 ~ 34 K). A possible reason could be the non-random distribution of magnetic rare earth ions on different crystallographic sites, presenting deviation from mean field like situation. The motivation for XAFS derives from detection of these circumstances. XAFS at Nd, Tb L3 edges reveals that 25% (Nd,Al) anti-site defect exists in Nd0.8Tb0.2Al2. This implies that Nd atoms occupy two different sites. In contrast, Tb preferentially substitutes only one of the Nd sites. The implication of these results upon magnetic compensation is discussed.

We employ XSW assisted XAFS at Ni K edge to characterize ion-irradiated Pt/Ni/C multilayer, particularly the nanoclusters formed within C layer, revealed by X-TEM and angle-resolved fluorescence studies. Retrieving the structural model from XAFS coordination results involved intriguing steps such as accounting for the intensity variation across the layers, determination of extra pre-diffused Ni into C layer (beyond the reflectivity determined roughness) and decoupling interfacial, layer and cluster coordination. The clusters are determined to be Ni centered Ni-Pt bimetallic nanoclusters (Ni:Pt = 60:40), formed due to irradiation induced diffusion of Pt atoms from the disrupted Pt/C interface towards pre-diffused Ni atoms present in C layer. They are highly disordered beyond nearest neighbor and resemble glassy structure which could find wide-scale applications in magnetic devices.

The dispersive XAFS beamline BL-08 at the INDUS-2 synchrotron radiation source, RRCAT, Indore uses a bent Si (111) crystal as dispersive-cum-focusing element and a position sensitive CCD detector to enable instantaneous measurement of the whole XAFS spectrum around the absorption edge of interest. This beamline is ideal for characterisation of materials under high pressure using Diamond Anvil Cell with ~50 ?m spot size. For this setup, the theoretically determined spot size (Horizontal ? Vertical) varies between 17 ? 137 ?m and 37 ? 142 ?m for the x-ray energy range 5 keV-20 keV. To reduce the vertical spot size to