Search results for "Period"

"Płynie Wisła, płynie..." : motyw rzeki w literaturze międzywojennego "Płomyka" (1917-1939)

2017

THE ROLE OF CALCIUM AS A METALLOTHERAPEUTIC DRUG

2005

Cave bear occupation in Schwabenreith Cave, Austria, during the early last glacial: constraints from 230 Th/U‐dated speleothems

2019

The cave bear was a prominent member of the Upper Pleistocene fauna in Eurasia. While breakthroughs were recently achieved with respect to its phylogeny using ancient DNA techniques, it is still challenging to date cave bear fossils beyond the radiocarbon age range. Without an accurate and precise chronological framework, however, key questions regarding the palaeoecology cannot be addressed, such as the extent to which large climate swings during the last glacial affected the habitat and possibly even conditioned the final extinction of this mammal. Key to constraining the age of cave bear fossils older than the lower limit of radiocarbon dating is to date interlayered speleothems using 23…

Enduring Sacred Places: The Astronomical Orientation of the Iberian Cave-Sanctuary of Cueva Santa del Cabriel in Spain

2019

This paper presents the results of an archaeoastronomical study of the Iberian Iron Age cave-sanctuary of Cueva Santa del Cabriel, near the town of Mira in the province of Cuenca, Castilla-La Mancha, central Spain, together with a review of the latest archaeological and ethnographical data about the site. We found that the cave's 12 m-long access corridor is oriented precisely along the summer solstice sunset, so that the north wall of the main gallery is partially illuminated by sunlight at this time. Although the cave was in use from the Late Chalcolithic, it became an important religious centre in the Iberian period. After an apparent hiatus during the Roman and Islamic occupations, its …

A half-metallic half-Heusler alloy having the largest atomic-like magnetic moment at optimized lattice constant

2016

For half-Heusler alloys, the general formula is XYZ, where X can be a transition or alkali metal element, Y is another transition metal element, typically Mn or Cr, and Z is a group IV element or a pnicitide. The atomic arrangements within a unit-cell show three configurations. Before this study, most of the predictions of half-metallic properties of half-Heusler alloys at the lattice constants differing from their optimized lattice constant. Based on the electropositivity of X and electronegativity of Z for half-Heusler alloys, we found that one of the configurations of LiCrS exhibits half-metallic properties at its optimized lattice constant of 5.803Å, and has the maximum atomic-like magn…

Structure and dielectric properties of Na0.5Bi0.5TiO3-CaTiO3 solid solutions

2016

Despite wide studies of Na0.5Bi0.5TiO3, structure of this material and its connection with the observed physical properties still raise numerous questions due to mutually contradicting results obtained. Here, structure and dielectric properties of poled and unpoled Na0.5Bi0.5TiO3-CaTiO3 solid solutions are studied, projecting the obtained concentration dependence of structure and dielectric properties on pure Na0.5Bi0.5TiO3 as the end member of this material group. X-ray diffraction patterns for Na0.5Bi0.5TiO3-CaTiO3 solid solutions reveal dominating of an orthorhombic Pnma phase, even for the compositions approaching the end composition (Na0.5Bi0.5TiO3), whereas structure of pure Na0.5Bi0.…

Assembling Halogen-Bonded Capsules via Cation Exchange

2017

Dr. Lotta Turunen is currently a postdoctoral researcher within Acad. Prof. Kari Rissanen's research group at the University of Jyvaskyla in Finland. Under his supervision, she obtained her MSc in organic chemistry and completed her PhD in chemistry in late September 2017. Her research focused on designing, synthesizing, and characterizing halogen-bonded supramolecular assemblies, capsules, and cages.

Towards the synthesis of substituted porphyrins by a pyridyl group bearing a reactive functionality

2010

Pyridyl-substituted porphyrins bearing a reactive functionality were prepared via Suzuki cross-coupling reactions and resulted in very good yields. These compounds are precursors of new porphyrin architectures able to coordinate two metals: one in the porphyrin core and the second around the pyridyl moiety. During the coupling reactions, a higher reactivity of a chloro picolyl group was evidenced compared to a bromo function on the same reacting molecule.

A polar/π model of interactions explains face-to-face stacked quinoid rings: a case study of the crystal of potassium hydrogen chloranilate dihydrate

2015

International audience; The nature of interactions between face-to-face staggered stacked quinoid rings with pi-systems, observed with a short inter-ring centroid. centroid distance, is analyzed by experimental and theoretical methods. Charge density studies based on X-ray diffraction and DFT calculations, complemented by impedance spectroscopy, were employed to define the electronic and structural characteristics of the quinoid rings responsible for their interactions within the crystal packing. The crystal packing is mainly stabilized by strong electrostatic interactions between the K+ cation and the hydrogen chloranilate anion. The proximity and orientation of the stacked quinoid rings i…

The Cu(II) complex of a C-lipophilized 13aneN4 macrocycle with an additional protonable amino group as micellar anion receptor.

2009

Three 13aneN4 macrocyclic ligands have been prepared bearing a -CH(2)NHR side arm (R = H, n-C(5)H(11), n-C(10)H(21)) on a carbon atom. When Cu(2+) is complexed in the macrocyclic ring, the amino group of the side arm undergoes an acid-base protonation equilibrium but it is not able to coordinate apically the metal cation even when it is deprotonated. The Cu(2+) complex with the ligand bearing the longest appended aliphatic chain is fully confined inside Triton X-100 micelles, and its ability to bind and sequestrate a series of anions inside micelles has been studied at two different pH values, i.e. both with protonated and neutral side-arm amino group. The favourable role played by the prot…