Search results for " glass"
showing 10 items of 409 documents
Microwave surface impedance of proximity-coupled superconducting (Nb)/spin-glass (CuMn) bilayers
1998
The surface impedance of Nb/CuMn (superconducting/spin-glass) bilayers has been measured at 10 GHz with the parallel plate resonator technique to obtain information about the exotic behavior of the order parameter in superconducting/magnetic proximity systems. The data strongly differs from the superconducting/normal-metal case, showing the magnetic nature of the CuMn layer, which acts as a weak ferromagnet. The results are described in the framework of two models for the electrodynamics of superconducting/ferromagnetic (S/M) bilayers characterized by a proximity-coupling length scale which is independent of temperature.
Residual Stresses in Glasses
2013
The history dependence of the glasses formed from flow-melted steady states by a sudden cessation of the shear rate $\dot\gamma$ is studied in colloidal suspensions, by molecular dynamics simulations, and mode-coupling theory. In an ideal glass, stresses relax only partially, leaving behind a finite persistent residual stress. For intermediate times, relaxation curves scale as a function of $\dot\gamma t$, even though no flow is present. The macroscopic stress evolution is connected to a length scale of residual liquefaction displayed by microscopic mean-squared displacements. The theory describes this history dependence of glasses sharing the same thermodynamic state variables, but differi…
Short-term occupations at high elevation during the Middle Paleolithic at Kalavan 2 (Republic of Armenia).
2021
The Armenian highlands encompasses rugged and environmentally diverse landscapes and is characterized by a mosaic of distinct ecological niches and large temperature gradients. Strong seasonal fluctuations in resource availability along topographic gradients likely prompted Pleistocene hominin groups to adapt by adjusting their mobility strategies. However, the role that elevated landscapes played in hunter-gatherer settlement systems during the Late Pleistocene (Middle Palaeolithic [MP]) remains poorly understood. At 1640 m above sea level, the MP site of Kalavan 2 (Armenia) is ideally positioned for testing hypotheses involving elevation-dependent seasonal mobility and subsistence strateg…
Conectando testamentos: Números como tipo en Biblia Pauperum y Speculum Humanae Salvationis
2020
ABSTRACT: In the close typological relationship established in the Middle Ages between the Old and New Testaments, the Book of Numbers becomes an exemplary Christological and Mariological prefigurative example. The episodes of the Murmuring of Miriam and Aaron, the Spies from Canaan, the Rebellion of Korah, Dathan, and Abiram, the Brazen Serpent, the Budding of Aaron’s Rod and the Prophecy of Balaam, constitute types of New Testament passages collected in the Biblia Pauperum and the Speculum Humanae Salvationis, whose repercussion will be felt in Medieval and Modern Art as a theological visual synthesis present in stained glass windows, sculptures of portals, tapestries, goldsmith works and…
Upconversion luminescence of a transparent glass ceramics with hexagonal Na(Gd,Lu)F4 nanocrystals
2017
Novel Er3+ doped transparent glass ceramics containing hexagonal Na(Gd,Lu)F4 nanocrystals were prepared from oxyfluoride glasses. The distribution of rare earth ions in the crystalline and glassy phase has been analyzed by X-ray diffraction and erbium luminescence decay kinetics measurement. A strong deviation of rare earth ion content in fluoride nanocrystals in comparison to the base glass has been observed. Preferential incorporation of Gd3+ over Lu3+ ions in the fluoride lattice leads to the stabilization of hexagonal Na(Gd,Lu)F4 structure and prevents the formation of cubic fluorite type solid solutions. A considerable enhancement of upconversion luminescence correlates with the format…
Electron paramagnetic resonance and photoluminescence investigation of europium local structure in oxyfluoride glass ceramics containing SrF2 nanocry…
2017
Different compositions of europium doped aluminosilicate oxyfluoride glass ceramics prepared in air atmosphere have been studied by electron paramagnetic resonance (EPR) and optical spectroscopy methods. X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements show presence of homogenously distributed SrF2 nanocrystals after the heat treatment of the precursor glass. Efficient Eu3+ incorporation in the high symmetry environment of glass ceramics is observed from the photoluminescence spectra. EPR spectra indicate Eu3+ → Eu2+ reduction upon precipitation of crystalline phases in the glass matrix. For composition abundant with Eu2+ in the glassy state such behaviour is …
Līvānu stikla fabrikas vēsture no 1970. gada līdz 1995. gadam
2019
Bakalaura darba temats ir “Līvānu stikla fabrikas vēsture no 1970. gada līdz 1995. gadam”. Šī bakalaura darba galvenais mērķis ir apkopot informāciju par Līvānu stikla fabriku dokumentos, publikācijas un mutvārdu vēstures stāstos laika posmā no 1975. gada līdz 1992. gadam un salīdzināt galvenos procesus un notikumus, kas notikuši fabrikas vēsturē. Tā rezultātā noskaidrot Līvānu stikla fabrikas nozīmi. Pētījuma rezultātā tapis bakalaura darbs, kur tika izpētīta un apzināta informācija par Līvānu stikla fabriku, tās vēsturi, galvenajiem attīstības posmiem, sabiedrisko dzīvi un norieta periodu. Pētījumā izmantoti Līvānu novada Centrālās bibliotēkās pieejamie novadpētniecības materiāli. Padziļi…
Human nasoseptal chondrocytes maintain their differentiated phenotype on PLLA scaffolds produced by thermally induced phase separation and supplement…
2018
Damage of hyaline cartilage such as nasoseptal cartilage requires proper reconstruction, which remains challenging due to its low intrinsic repair capacity. Implantation of autologous chondrocytes in combination with a biomimetic biomaterial represents a promising strategy to support cartilage repair. Despite so far mostly tested for bone tissue engineering, bioactive glass (BG) could exert stimulatory effects on chondrogenesis. The aim of this work was to produce and characterize composite porous poly(L-lactide) (PLLA)/1393BG scaffolds via thermally induced phase separation (TIPS) technique and assess their effects on chondrogenesis of nasoseptal chondrocytes. The PLLA scaffolds without or…
Materials, Techniques, and Conservation of Historic Stained Glass “Grisailles”
2015
A grisaille is a brown-blackish paint applied onto the inner surface of stained glass to draw the contours and details of the figures and to produce the effect of shades and volumes. Grisailles were traditionally made of finely ground oxides of iron but also of copper, zinc, lead, or manganese mixed with a flux such as lead ground glass and a binder and fixed onto the flat glass by firing. The grisailles have typical layer thickness varying between 10 and 100 µm and are formed by a complex mixture of pigment particles, crystalline, and amorphous reaction compounds, aging, and weathering compounds. The high brilliance, collimation, energy selection, and monochromacity of the SR beam are idea…
A Raman calibration for the quantification of SO42-groups dissolved in silicate glasses: Application to natural melt inclusions
2017
Sulfur is an important volatile element involved in magmatic systems. Its quantification in silicate glasses relies on state-of-the-art techniques such as electronprobe microanalyses (EPMA) or X-ray absorption spectroscopy but is often complicated by the fact that S dissolved in silicate glasses can adopt several oxidation states (S6+for sulfates or S2-for sulfides). In the present work, we use micro-Raman spectroscopy on a series of silicate glasses to quantify the S content. The database is constituted by 47 silicate glasses of various compositions (natural and synthetic) with S content ranging from 1179 to 13 180 ppm. Most of the investigated glasses have been synthesized at high pressur…