Analysis of earthy pigments in grounds of Baroque paintings

Sixteen samples of orange-red and yellow Fe-oxide earthy pigments mainly from bole grounds of Baroque paintings were studied by elemental and phase analysis and voltammetry. Fe, K, and Ti content were found to be suitable for further classification of those earthy pigments. According to the chemical and phase composition the yellow grounds were natural yellow ochres formed by intense chemical weathering in a moderate climate. Very similar phase and elemental composition of part of the orange-red boles indicated their similar geological origin or even their formation by calcination of yellow ochres. Part of the orange-red boles differed significantly from the yellow boles, especially in their increased content of Ti, indicating their relation to end products of intense weathering, e.g. laterites formed in a tropical climate. Analogous materials with a correspondingly large Ti content are not currently commercially available and their geological origin (provenance) is not clear. In several orange-red boles the intentional addition of rather coarse-grained haematite to natural ochre by the painters was assumed on the basis of Fe oxide content and crystallinity.     

Triangular Arrangement of Ferromagnetic Iron Chains in the High-TC Ferromagnet TiFe1−xOs2+xB2

Transition-metal borides (TMBs) containing B_n-fragment (n>3) have recently gained interest for their ability to enable exciting magnetic materials. Herein, we show that the B₄-containing TiFe_0.64(1)Os_2.36(1)B₂ is a new ferromagnetic TMB with a Curie temperature of 523(2) K and a Weiss constant of 554(3) K, originating from the chain of M₃-triangles (M=64 %Fe+36 %Os). The new phase was synthesized from the elements by arc-melting, and its structure was elucidated by single-crystal X-ray diffraction. It belongs to the Ti_1+xOs_2−xRuB₂-type structure (space group P 2 m, no. 189) and contains trigonal-planar B₄ boron fragments [B−B distance of 1.87(4) Å] interacting with M₃-triangles [M–M distances of 2.637(8) Å and 3.0199(2) Å]. The experimental results were supported by computational calculations based on the ideal TiFeOs₂B₂ composition, which revealed strong ferromagnetic interactions within and between the Fe₃-triangles. This discovery represents the first magnetically ordered Os-rich TMB, thus it will help expand our knowledge of the role of Os in low-dimensional magnetism of intermetallics and enable the design of such materials in the future.     

Assessing the fire risk of electrical cables using a cone calorimeter

Journal of Thermal Analysis and Calorimetry - The presented study deals with the fire risk of electrical cables. Samples of three-core electrical power cables and two-core electrical control cables...     

From 3D to 2D: Structural,Spectroscopic and Theoretical Investigations of the Dimensionality Reduction in the [PtAl2]δ− Polyanions of the Isotypic MPtAl2 Series (M=Ca–Ba,Eu)

Four new MPtAl₂ (M=Ca, Sr, Ba, Eu) compounds, adopting the orthorhombic MgCuAl₂-type structure, have been synthesized from the elements using tantalum ampoules. All compounds are obtained as platelet-shaped crystallites and exhibit an increasing moisture sensitivity with increasing size of the formal M cation. Structural investigations indicate a pronounced elongation of the crystallographic b-axis, which results in a significant distortion of the [PtAl₂]^δ− polyanion. Within the polyanion, layer-like arrangements can be found with bonding Pt−Al interactions within the slab; the increase of the b-axis can be attributed to increasing Al−Al distances and therefore decreasing interactions between the slabs, caused by the differently-sized formal M cations. While the alkaline earth (M=Ca, Sr) representatives exhibit Pauli paramagnetism, BaPtAl₂ shows diamagnetic behavior, finally EuPtAl₂ is ferromagnetic with T_C=54.0(5) K. The effective magnetic moment indicates that the Eu atoms are in a divalent oxidation state, which is confirmed by ¹⁵¹Eu Mössbauer spectroscopic investigations. Measurements below the Curie-temperature show a full magnetic hyperfine field splitting with B_hf=21.7(1) T. ²⁷Al and ¹⁹⁵Pt magic-angle spinning NMR spectroscopy corroborates the presence of single crystallographic sites for the Pt and Al atoms. The large ²⁷Al nuclear electric quadrupolar coupling constants confirm unusually strong electric field gradients, in agreement with the structural distortions and the respective theoretical calculations. X-ray photoelectron spectroscopy has been utilized to investigate the charge transfer within the polyanion. The Pt 4f binding energy decreases with decreasing electronegativity / ionization energy of the alkaline earth elements, suggesting an increasing electron density at the Pt atoms. Theoretical investigations underline the platinide character of the investigated compounds by Bader charge calculations. The analysis of the integrated crystal orbital Hamilton population (ICOHP) values, electron localization function (ELF) and isosurface analyses lead to a consistent structural picture, indicating stable layer-like arrangements of the [PtAl₂]^δ− polyanion.     

Evaluation of Antiproliferative Palladium(II) Complexes of Synthetic Bisdemethoxycurcumin towards In Vitro Cytotoxicity and Molecular Docking on DNA Sequence

Metallodrugs form a large family of therapeutic agents against cancer, among which is cisplatin, a paradigmatic member. Therapeutic resistance and undesired side effects to Pt(II) related drugs, prompts research on different metal–ligand combinations with potentially enhanced biological activity. We present the synthesis and biological tests of novel palladium(II) complexes containing bisdemethoxycurcumin (BDMC) 1 and 2. Complexes were fully characterized and their structures were determined by X-ray diffraction. Their biological activity was assessed for several selected human tumor cell lines: Jurkat (human leukaemic T-cell lymphoma), HCT-116 (human colorectal carcinoma), HeLa (human cervix epitheloid carcinoma), MCF-7 (human breast adenocarcinoma), MDA-MB-231 (human mammary gland adenocarcinoma), A549 (human alveolar adenocarcinoma), Caco-2 (human colorectal carcinoma), and for non-cancerous 3T3 cells (murine fibroblasts). The cytotoxicity of 1 is comparable to that of cisplatin, and superior to that of 2 in all cell lines. It is a correlation between IC₅₀ values of 1 and 2 in the eight studied cell types, promising a potential use as anti-proliferative drugs. Moreover, for Jurkat cell line, complexes 1 and 2, show an enhanced activity. DFT and docking calculations on the NF-κB protein, Human Serum Albumin (HSA), and DNA were performed for 1 and 2 to correlate with their biological activities.     

Colour conductivity of hard spheres

We present an analytic solution for the d-dimensional (d > 1) hard-sphere free flight trajectories in a thermostatted colour field. The solution shows that particles can only reach a finite distance in the direction perpendicular to the field in the absence of collisions. Using a numerical algorithm we designed to simulate many-body hard-sphere systems with curved trajectories, we study the onset of the instability leading to phase separation in the two-dimensional case for a range of field strengths and three densities. For the two fluid densities we find that phase separation occurs for sufficiently strong fields regardless of the initial configuration, and that the phase-separated state eventually becomes a collisionless, non-ergodic steady state. For solid densities the phase-separated configuration is stable and conducting, but is not an attractor for other charge distributions because of the impossibility of particle rearrangement.