Abstract: Single crystals with two different morphologies, black and brown, of C60 with about 12% C70 have been studied by synchrotron X-ray diffraction. Integrated intensities from 8 reflections show that the charge distribution of the C60 cluster is shell-like giving rise to an oscillatory behaviour in the diffracted intensities. From the intensities, the distance between diametrically opposite carbon atoms has been determined to be (7.24 +/- 0.22) angstrom. The thickness of the charge distribution of the shell can be estimated as 3.06 angstrom and the cavity within a C60 cluster to have a diameter of about 4.18 angstrom. The finite longitudinal width of the diffraction peaks from black crystals indicates a lack of long-range crystalline order. The rocking curves are about 7-degrees broad and depict an unusually smooth behaviour. This may be indicative of a glassy or hexatic phase. High-resolution electron microscopy allows small crystallites with a relatively well-defined orientation relationship to be identified. In contrast, brown crystals have long-range order.

Abstract: We extend the unsymmetrized self-consistent-field method (USF) for anharmonic crystals to layered non-Bravais crystals to investigate structural, dynamical and thermodynamic properties of a free-standing graphene monolayer. In this theory, the main anharmonicity of the crystal lattice has been included and the quantum corrections are taken into account in an h-expansion for the one-particle density matrix. The obtained result for the thermal expansion coefficient (TEC) of graphene shows a strong temperature dependence and agrees with experimental results by Bao et al. (Nat. Nanotechnol., 4 (2009) 562). The obtained value of TEC at room temperature (300 K) is -6.4 x 10(- 6) K- 1 and it becomes positive for T > T-alpha = 358K. We find that quantum effects are significant for T < 1000 K. The interatomic distance, effective amplitudes of the graphene lattice vibrations, adiabatic and isothermal bulk moduli, isobaric and isochoric heat capacities are also calculated and their temperature dependences are determined. Copyright (C) EPLA, 2014

Abstract: Charge carriers in single and multilayered graphene systems behave as chiral particles due to the particular lattice symmetry of the crystal. We show that the interplay between the meta-material properties of graphene multilayers and the pseudospinorial properties of the charge carriers result in the occurrence of Klein and anti-Klein tunneling for rhombohedral stacked multilayers. We derive an algebraic formula predicting the angles at which these phenomena occur and support this with numerical calculations for systems up to four layers. We present a decomposition of an arbitrarily stacked multilayer into pseudospin doublets that have the same properties as rhombohedral systems with a lower number of layers. Copyright (C) EPLA, 2013

Abstract: The use of non-invasive macroscopic imaging techniques is becoming more prevalent in the field of cultural heritage, especially to avoid invasive procedures that damage valuable artworks. For this purpose, an X-ray powder diffraction scanner (MA-XRPD) capable of visualising crystalline compounds in a highly specific manner was recently developed. Many inorganic pigments present in paintings fall into this category of materials. In this study, the 17th century oil painting Girl with a Pearl Earring (c. 1665) by Johannes Vermeer was analysed with a combination of transmission and reflection mode MA-XRPD. By employing this scanner in reflection mode, the relative sensitivity for compounds that are present at the paint surface could be increased, establishing it as a highly relevant technique for investigating the degradation processes that are ongoing at paint surfaces. Many of the original pigments employed by Vermeer could be identified, along with four secondary alteration products: gypsum (CaSO4 center dot 2H(2)O), anglesite (PbSO4), palmierite (K2Pb(SO4)(2)) and weddellite (CaC2O4 center dot 2H(2)O). The formation of gypsum was linked to the presence of chalk in the upper glaze layer while the formation of palmierite and weddellite is driven by the presence of lake pigments (and their substrates). In this manner, MA-XRPD can also be used to pinpoint locations relevant for sampling and synchrotron mu-XRPD analysis, which provides information on the microscopic make-up of the paint. A paint cross-section taken from an area rich in palmierite was analysed with synchrotron mu-XRPD, which confirmed the presence of this secondary compound at the interface of the upper paint layer with the ground layer as well as the presence of anglesite in the ground layer. The capacity of MA-XRPD to identify and chart secondary alteration products in a non-invasive manner has only very recently been demonstrated and makes it a highly relevant technique for the assessment of the chemical condition of works of art.

Abstract: Jackson Pollock's Number 1A, 1948 painting was investigated using in situ scanning macro-x-ray fluorescence mapping (MA-XRF) to help characterize the artist's materials and his creative process. A multivariate curve resolution-alternating least squares (MCR-ALS) approach was used to examine the hyperspectral data and obtain distribution maps and signature spectra for the paints he used. The composition of the paints was elucidated based on the chemical elements identified in the signature spectra and a tentative list of pigments, fillers and other additives is proposed for eleven different paints and for the canvas. The paint distribution maps were used to virtually reconstruct the artist process and document the sequence and manner in which Pollock applied the different paints, using deliberate and specific gestures.

Abstract: Results are presented of in situ studies of 1 MeV electron irradiation induced (113) defect generation in silicon containing different types and concentrations of extrinsic point defects. A semiquantitative model is developed describing the influence of interfaces and stress fields and of extrinsic point defects on the (113) defect generation in silicon during irradiation. The theoretical results obtained are correlated with experimental data obtained on silicon uniformly doped with boron and phosphorus and with observations obtained by irradiating cross-sectional samples of wafers with highly doped surface layers. It is shown that in situ irradiation in a high voltage election microscope is a powerful tool for studying local point defect reactions in silicon. (C) 1995 The Institute of Materials.

Abstract: Synchrotron radiation micro-X-ray fluorescence and micro-X-ray diffraction analysis, micro-computed tomography and transmission electron microscopy were used to investigate the microstructure of turbine blades made of a second generation nickel based superalloy CMSX-4 manufactured by investment casting process via Bridgman technique. The dependence of microstructure on process parameters, among others, on the withdrawal rate was analysed. The results set the stage for optimising the microstructure of the blades in terms of their mechanical properties.

Abstract: Using Laser Microprobe Mass Analysis (LAMMA), we studied the chemical composition of lead-induced intranuclear inclusions in rat kidney tissue prepared by three different wet chemical fixation procedures for transmission electron microscopy. Fixation with glutaraldehyde-Na2S gave the same results as fixation with glutaraldehyde only: a high lead concentration could be detected. Therefore, for lead strongly bound to proteins, precipitation procedures are not essential. Post-fixation with osmium tetroxide drastically changed the composition of the inclusions: the lead concentration decreased substantially, while sodium, calcium, and barium were introduced. The osmium tetroxide fixative was found to be the source of the contamination. It also contained aluminum, and we suggest that other proteins (e.g., in neurofibrillary tangles) might be able to take up Al out of solution and that care must be exercised in interpreting the microanalytical results of osmium-fixed material. For the microanalysis of the lead inclusions, fixation with glutaraldehyde only provides a good compromise between preservation of the ultrastructure and maintenance of the element distribution.

Abstract: This paper reviews and compares 11 studies that have estimated external costs of fossil electricity generation by benefits transfer. These studies include 13 countries and most of these countries are developing countries. The impact pathway approach is applied to estimate the environmental impact arising from fossil fuel-fired power plant's air emission and the related damages on human health. The estimated damages are used to value the monetary external costs from fossil fuel electricity generation. The estimated external costs in the 13 countries vary from 0.51 to 213.5 USD (2005) per MWh due to differences in fossil fuel quality, location, technology, and efficiency of power plants and additionally differences in assumptions, monetization values, and impact estimations. Accounting for these externalities can indicate the actual costs of fossil energy. The results can be applied by policy makers to take measures to avoid additional costs and to apply newer and cleaner energy sources. The described methods in the selected studies for estimating the external costs with respect to incomplete local data can be applied as a useful example for other developing countries.

Abstract: Ceramic materials are prone to slow crack growth, resulting in strength degradation over time. Although yttria-stabilized zirconia (Y-TZP) ceramics have higher crack resistance than other dental ceramics, their aging susceptibility threatens their long-term performance in aqueous environments such as the oral cavity. Unfortunately, increasing the aging resistance of Y-TZP ceramics normally reduces their crack resistance. Our recently conducted systematic study of doping 3Y-TZP with various trivalent cations revealed that lanthanum oxide (La2O3) and aluminum oxide (Al2O3) have the most potent effect to retard the aging kinetics of 3Y-TZP. In this study, the crack-propagation behavior of La2O3 and Al2O3 co-doped 3Y-TZP ceramics was investigated by double-torsion methods. The grain boundaries were examined using scanning transmission electron microscopy and energy-dispersive spectroscopy (STEM-EDS). Correlating these analytic data with hydrothermal aging studies using different doping systems, a strategy to strongly bind the segregated dopant cations with the oxygen vacancies at the zirconia-grain boundary was found to improve effectively the aging resistance of Y-TZP ceramics without affecting the resistance to crack propagation.