Abstract: ''1201'' Tl-based substituted cuprates of the type (Tl1-xMx) Sr2CuO5 have been synthesized for M = Nb, Ta, or W. These materials do not superconduct due to a statistical distribution of some of the M for Cu. The remarkable feature of these materials is the ordering observed between Tl and M in the (Tl1-xMx-epsilon)O plane. The type of ordering depends on the composition and shows remarkable similarities with the ordering in Ni-Mo or other so-called 1 1/2 0 type fcc-based alloys or with the ordering in rocksalt oxides TiOx. The short-range order, for M = W, can be readily interpreted in terms of a mixing of nano-clusters with two different compositions. These observations of two-dimensional ordering confirm recent ideas about ordering in three-dimensional fcc-based alloys.

Abstract: We present a first-principles computational study of CO and OH adsorption on non-polar ZnO (10¯10) surfaces doped with indium. The calculations were performed using a model ZnO slab. The position of the In dopants was varied from deep bulk-like layers to
the surface layers. It was established that the preferential location of the In atoms is at the surface by examining the dependence of
the defect formation energy as well as the surface energy on In location. The adsorption sites on the surface of ZnO and the energy
of adsorption of CO molecules and OH-species were determined in connection to In doping. It was found that OH has higher
bonding energy to the surface than CO. The presence of In atoms at the surface of ZnO is favorable for CO adsorption, resulting
in an elongation of the C-O bond and in charge transfer to the surface. The effect of CO and OH adsorption on the electronic
and conduction properties of surfaces was assessed. We conclude that In-doped ZnO surfaces should present a higher electronic
response upon adsorption of CO.

Abstract: Branched plasmonic nanocrystals (NCs) have attracted much attention due to electric field enhancements at their tips. Seeded growth provides routes to NCs with defined branching patterns and, in turn, near‐field distributions with defined symmetries. Here, a systematic analysis was undertaken in which seeds containing different distributions of planar defects were used to grow branched NCs in order to understand how their distributions direct the branching. Characterization of the products by multimode electron tomography and analysis of the NC morphologies at different overgrowth stages indicate that the branching patterns are directed by the seed defects, with the emergence of branches from the seed faces consistent with minimizing volumetric strain energy at the expense of surface energy. These results contrast with growth of branched NCs from single‐crystalline seeds and provide a new platform for the synthesis of symmetrically branched plasmonic NCs.

Abstract: RuCp2 (ruthenocene) and RuCpPy (cyclopentadienyl pyrrolyl ruthenium) complexes are used in ruthenium (Ru) atomic layer deposition (ALD) but exhibit a markedly different reactivity with respect to the substrate and co-reactant. In search of an explanation, we report here the results of a comparative study of the heterolytic and homolytic dissociation enthalpy of these two ruthenium complexes, making use of either density functional theory (DFT) or multiconfigurational perturbation theory (CASPT2). While both methods predict distinctly different absolute dissociation enthalpies, they agree on the relative values between both molecules. A reduced heterolytic dissociation enthalpy is obtained for RuCpPy compared to RuCp2, although the difference obtained from CASPT2 (19.9 kcal/mol) is slightly larger than the one obtained with any of the DFT functionals (around 17 kcal/mol). Both methods also agree on the more pronounced stability of the Cp- ligand in RuCpPy than in RuCp2 (by around 9 kcal/mol with DFT and by 6 kcal/mol with CASPT2).

Abstract: The anion-deficient perovskite 4H-BaMnO2+x has been obtained by a topotactic reduction, with LiH, of the hexagonal perovskite 4H-BaMnO3−x. The crystal structure of 4H-BaMnO2+x was solved using electron diffraction and X-ray powder diffraction and further refined using neutron powder diffraction (S.G. Pnma, a = 10.375(2) Å, b = 9.466(2) Å, c = 11.276(3) Å, at 373 K). The orthorhombic superstructure arises from the ordering of oxygen vacancies within a 4H (chch) stacking of close packed c-type BaO2.5 and h-type BaO1.5 layers. The ordering of the oxygen vacancies transforms the Mn2O9 units of face-sharing MnO6 octahedra into Mn2O7 (two corner-sharing tetrahedra) and Mn2O6 (two edge-sharing tetrahedra) groups. The Mn2O7 and Mn2O6 groups are linked by corner-sharing into a three-dimensional framework. The structures of the BaO2.5 and BaO1.5 layers are different from those observed previously in anion-deficient perovskites providing a new type of order pattern of oxygen atoms and vacancies in close packed structures. Magnetization measurements and neutron diffraction data reveal 4H-BaMnO2+x adopts an antiferromagnetically ordered state below TN ≈ 350 K.

Abstract: A simple and low-cost method to create metal−metal hybrid nanostructures possessing fairly regularly spaced hot-spots of surface plasmon resonances is proposed. The nanohybrid structure was prepared via self-assembly during a simple drop-casting procedure, using chemically synthesized silver nanowires and silver nanoparticles prepared in a single batch of a polyol process. Wide field illumination of these nanohybrids produced hot-spots with spacings of around 500 nm to 1 ìm. The intensity of the emission/scattering from the hot-spots fluctuates over time. The proposed structure can be useful for the development of molecular-sensors or as a substrate for surface enhanced Raman/fluorescence spectroscopy.

Abstract: We study the structure and phase behavior of fullerene-cubane C60·C8H8 by Monte Carlo simulation. Using a simple potential model capturing the icosahedral and cubic symmetries of its molecular constituents, we reproduce the experimentally observed phase transition from a cubic to an orthorhombic crystal lattice and the accompanying rotational freezing of the C60 molecules. We elaborate a scheme to identify the low-temperature orientations of individual molecules and to detect a pattern of orientational ordering similar to the arrangement of C60 molecules in solid C60. Our configuration of orientations supports a doubled periodicity along one of the crystal axes.

Abstract: We consider an interface between two strong time-reversal invariant topological insulators having surface states with opposite spin chirality, or equivalently, opposite mirror Chern number. We show that such an interface supports gapless modes that are protected by mirror symmetry. The interface states are investigated with a continuum model for the Bi2Se3 class of topological insulators that takes into account terms up to third order in the crystal momentum, which ensures that the model has the correct symmetry. The model parameters are obtained from ab initio calculations. Finally, we consider the effect of rotational mismatch at the interface, which breaks the mirror symmetry and opens a gap in the interface spectrum.

Abstract: Density functional theory is widely used to gain insights into molecule−metal surface reaction networks, which is important for a better understanding of catalysis. However, it is well-known that generalized gradient approximation (GGA)
density functionals (DFs), most often used for the study of reaction networks, struggle to correctly describe both gas-phase molecules and metal surfaces. Also, GGA DFs typically underestimate reaction barriers due to an underestimation of the selfinteraction energy. Screened hybrid GGA DFs have been shown to reduce this problem but are currently intractable for wide usage. In this work, we use a more affordable meta-GGA (mGGA) DF in combination with a nonlocal correlation DF for the first time to study and gain new insights into a catalytically important surface
reaction network, namely, CO2 hydrogenation on Cu. We show that the mGGA DF used, namely, rMS-RPBEl-rVV10, outperforms typical GGA DFs by providing similar or better predictions for metals and molecules, as well as molecule−metal surface adsorption
and activation energies. Hence, it is a better choice for constructing molecule−metal surface reaction networks.

Abstract: Morphological characterization of nanoparticle assemblies and hybrid nanomaterials is critical in determining their structure-property relationships as well as in the development of structures with desired properties. Electron tomography has become a widely utilized technique for the three-dimensional characterization of nanoparticle assemblies. However, the extraction of quantitative morphological parameters from the reconstructed volume can be a complex and labor-intensive task. In this study, we aim to overcome this challenge by automating the volumetric segmentation process applied to three-dimensional reconstructions of nanoparticle assemblies. The key to enabling automated characterization is to assess the performance of different volumetric segmentation methods in accurately extracting predefined quantitative descriptors for morphological characterization. In our methodology, we compare the quantitative descriptors obtained through manual segmentation with those obtained through automated segmentation methods, to evaluate their accuracy and effectiveness. To show generality, our study focuses on the characterization of assemblies of CdSe/CdS quantum dots, gold nanospheres and CdSe/CdS encapsulated in polymeric micelles, and silica-coated gold nanorods decorated with both CdSe/CdS or PbS quantum dots. We use two unsupervised segmentation algorithms: the watershed transform and the spherical Hough transform. Our results demonstrate that the choice of automated segmentation method is crucial for accurately extracting the predefined quantitative descriptors. Specifically, the spherical Hough transform exhibits superior performance in accurately extracting quantitative descriptors, such as particle size and interparticle distance, thereby allowing for an objective, efficient, and reliable volumetric segmentation of complex nanoparticle assemblies.

Abstract: In this study, the multi-layer self-assembled molecular network formation of an alkylated tetrathiafulvalene compound is studied at the liquid-solid interface between 1-phenyloctane and graphite. A combined theoretical/experimental approach associating force-field and quantum-chemical calculations with scanning tunnelling microscopy is used to determine the two-dimensional self-assembly beyond the monolayer, but also to further the understanding of the molecular adsorption conformation and its impact on the molecular packing within the assemblies at the monolayer and bilayer level.

Abstract: The painting Saul and David, considered to date from c. 1652 and previously attributed to Rembrandt van Rijn and/or his studio, is a complex work of art that has been recently subjected to intensive investigation and conservation treatment. The goal of the research was to give insight into the painting's physical construction and condition in preparation for conservation treatment. It was also anticipated that analysis would shed light on authenticity questions and Rembrandt's role in the creation of the painting. The painting depicts the Old Testament figures of King Saul and David. At left is Saul, seated, holding a spear and wiping a tear from his eye with a curtain. David kneels before him at the right playing his harp. In the past, the large sections with the life-size figures were cut apart and later reassembled. A third piece of canvas was added to replace a missing piece of canvas above the head of David. As part of the investigation into the authenticity of the curtain area, a number of paint micro samples were examined with LM and SEM-EDX. Given that the earth, smalt and lake pigments used in the painting could not be imaged with traditional imaging techniques, the entire painting was also examined with state of the art non-destructive imaging techniques. Special attention was devoted to the presence of cobalt-containing materials, specifically the blue glass pigment smalt considered characteristic for the late Rembrandt. A combination of quantitative electron microprobe analysis and macroscopic X-ray fluorescence scanning revealed that three types of cobalt-containing materials are present in the painting. The first type is a cobalt drier that was found in the overpaint used to cover up the canvas inset and the joins that were added in the 19th century. The other two Co-containing materials are part of the original paint used by Rembrandt and comprise two varieties of smalt, a K-rich glass pigment that derives its gray-blue color by doping with Co-ions. Smalt paint with a higher Ni content (NiO:CoO ratio of around 1:4) was used to depict the blue stripes in Saul's colorful turban, while smalt with a lower Ni content was employed (NiO:CoO ratio of around 1:5) for the broad expanses of Saul's garments. The presence of two types of smalt not only supports the recent re-attribution of the painting to Rembrandt, but also that the picture was painted in two phases. Saul's dark red garment is painted in a rough, “loose” manner and the now discolored smalt-rich layer was found to have been partially removed during a past restoration treatment/s. In contrast, the blue-green smalt in the turban is much better preserved and provides a colorful accent. While the use of different types of smalt in a Rembrandt painting has been previously identified using quantitative EDX analysis of paint cross-sections, to the best of our knowledge this is the first time such a distinction has been observed in a 17th-century painting using non-destructive imaging techniques. In addition to the XRF-based non-invasive elemental mapping, hyperspectral imaging in the visual to near-infrared (VNIR) region was also carried out. (C) 2016 Elsevier B.V. All rights reserved.