Search results for "ALK"
showing 10 items of 4314 documents
Ceramics from Samshvilde (Georgia): A pilot archaeometric study
2020
Abstract This archaeometric study deals with seven samples of prehistoric pottery and, for the first time in Georgian studies, thirteen samples of glazed medieval pottery. All specimens were collected at Samshvilde, the most remarkable archaeological complex in southern Georgia and believed to represent locally-manufactured products. Two additional samples of raw materials composed of clay, silt, and sand were collected near the site and used to compare composition. Several analytical techniques were applied: Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Electron Probe Microanalysis (EPMA), X-ray Diffraction (XRD) and X-ray Fluorescence (XRF). The results allowed to build a c…
Luminescence of silica glass containing aluminum oxide
2004
Abstract Optical properties of silica glass with different doping of Al 2 O 3 up to 1.5 mol% were studied. Alumina stimulates creation of a luminescence centers with specific band at 3.3 eV. A new band at 8.2 eV appears in luminescence excitation spectra. There is transport of energy to other luminescence centers associated with an impurity (Ag, Ce) at this energy. Alumina stimulates creation of E′ centers under γ-irradiation beside trapped hole on AlO 4 tetrahedron as well as creation of a silicon related oxygen deficient center (SiODC) under cathodoexcitation. Visually, the samples look inhomogeneous even after γ-irradiation. The explanation could be heterogeneity of the samples. Alumina …
The defined adsorption site of sodium on the TiO2(110)–(1×1) surface
2004
The adsorption site of sodium on the TiO2(1 1 0)–(1 × 1) surface was studied by extended X-ray absorption fine structure. For coverage ranging between 0.25 and 0.5 ML, we find that sodium is on an ‘in-between' site where it is bound to two bridging oxygen atoms at 2.25 Å and one in-plane oxygen atom at 2.40 Å, in full agreement with DFT calculations. At higher coverage the site becomes an hollow site where the sodium atom is equidistant to the three oxygen atoms at 2.30 Å, while metallic sodium clusters are also formed at the surface.
Results from burial experiments with simulated medieval glasses
2002
ABSTRACTDuring several hundred years of burial in the soil, glasses, especially those with medieval compositions, develop heavily corroded surfaces, showing phenomena such as local pitting, laminated layers and browning effects. For this study the damage phenomena have been characterised for three original glasses, using conventional methods (light microscopy and SEM of the surface and cross sections) and microfocus X-ray computed tomography (mCT), a new non-destructive analytical technique.The degradation of glass in the soil depends on a variety of parameters, concerned with the glass itself and with the burial environment. Since synergetic effects may complicate any mechanistic studies, …
Ni-Based Alloy Nanostructured Electrodes for Alkaline Electrolyzers
In water alkaline electrolyzer field, the development of Nickel-based nanostructured electrode is one of the possible ways to improve the water electrolysis efficiency
ChemInform Abstract: Mercaptophenol-Protected Gold Colloides as Nuclei for the Crystallization of Inorganic Minerals: Templated Crystallization on Cu…
2010
The transport of ions across monoolein bilayers mediated by synthetic macrocyclic carriers
1989
The efficiency as carriers for the alkali and the alkaline earth ions across monoolein bilayers of three macrocyclic compounds has been investigated by conductometric measurements. The results show that although the three compounds have the optimum cavity size for fitting potassium and barium cations, their efficiency in ionic transport is quite different. These discrepancies are rationalized on the basis of the overlap of the water-diazacrown and cation-ligand interactions on the carrier mechanism.
Caracterización de barita cubana y su reducción carbotérmica en horno de microondas
2007
The Cuban Barite (BaSO4) is characterized by X ray diffraction, chemical analysis and scanning electron microscopy. The principal components are identified and its characteristic morphology is shown. Its carbothermic reduction under microwave irradiation is carried out with the purpose of to improve the yield of this stage during the mineral transformation process in reagent of barium of diverse applications. La barita cubana (BaSO4) se ha caracterizado por difracción de rayos X, análisis químico y microscopía electrónica de barrido. Se han identificado sus componentes mayoritarios y así mismo se muestra su morfología característica. Se ha realizado su reducción carbotérmica en horno de mic…
Homoleptic heavy alkaline Earth and europium triazenides.
2009
The sigma-bond metathesis reaction between PhSiH(3) and the heteroleptic metal pentafluorophenyl compounds [Dmp(Tph)N(3)MC(6)F(5)(thf)(n)] (Dmp = 2,6-Mes(2)C(6)H(3) with Mes = 2,4,6-Me(3)C(6)H(2); Tph = 2-TripC(6)H(4) with Trip = 2,4,6-(i)Pr(3)C(6)H(2); n = 1, 2; M = Sr, Ba, Eu) supported by sterically crowded, biphenyl- and terphenyl-substituented triazenido ligands afforded the first homoleptic stontium, barium, and europium triazenides [M{N(3)Dmp(Tph)}(2)] {M = Sr (2), Ba (4), Eu (5)}. Crystallization of 2 from an n-heptane/1,2-dimethoxyethane mixture gave the complex [Sr{N(3)Dmp(Tph)}(2)(dme)] (3). All new compounds have been characterized by (1)H and (13)C NMR spectroscopy (not 5), ele…
Interactions of Ultra-cold Alkaline-earth-like and Alkali Atoms with Light
2019
This paper presents the experimental results of photoionization and photoassociation experiments performed with both ultra-cold alkaline-earth-like and alkali atoms. Photoionization cross-section was studied for 88Sr at the blue magic 390 nm wavelength as well as for 87Rb at 254 nm. We also present preliminary results of photoassociation spectroscopy of the molecular line detected near the dissociation threshold of the excited Rb*Hg molecule at D1 Rb line (795 nm).