Search results for " Petr"
showing 10 items of 1574 documents
Tra Elimi e Greci. La ceramica di età arcaica dai contesti di fondazione della cinta muraria di Erice
2018
Questa monografia costituisce la sintesi dello studio effettuato dall'autrice sulle ceramiche di produzione locale e di importazione rinvenute durante le campagne di scavo realizzate negli anni 2010-2014 lungo la cinta muraria di Erice. Sono stati analizzati in modo approfondito, fornendone un catalogo dettagliato, i frammenti ceramici provenienti dagli strati di fondazione delle mura di età arcaica, studiati nell'ambito del loro contesto di scavo.
Discrimination and provenances of Phoenician red slip ware using both the solid state electrochemistry and petrographic analyses
2020
[EN] Solid state electrochemistry based on the voltammetry of immobilized microparticles (VIMP) methodology is applied to a series of 80 Phoenician Red Slip samples from the archaeological sites of Motya (Sicily, Italy), Mogador (Morocco), Ramat-Rahel (Israel), Sulky (Sardinia, Italy), Tas Silg (Malta), Pantelleria (Italy), and Cadiz (Spain), dated from the 8(th) to the 6(th) century BC. Upon attachment of sub-microsamples to graphite electrodes in contact with aqueous H2SO4 electrolyte, voltammetric features due to the reduction of Fe(III) minerals and the oxidation of Fe(II) ones, complemented with electrocatalytic effects on oxygen reduction and oxygen evolution reactions, provide charac…
Strontium/lithium ratio in aragonitic shells of Cerastoderma edule (Bivalvia) — A new potential temperature proxy for brackish environments
2015
Abstract Quantitative reconstruction of water temperature from shells of bivalve mollusks is still a very challenging task. For example, in highly variable environments such as intertidal zones, shell oxygen isotope values can only provide reliable temperature estimates if the δ18Owater signature during the time of growth is known. Furthermore, trace element-to-calcium ratios such as Sr/Ca or Mg/Ca often do not serve as reliable paleothermometers, because their incorporation into bivalve shells is known to be strongly biologically controlled. Here, we present a potential novel temperature proxy which is based on the Sr/Lishell ratio of the intertidal bivalve Cerastoderma edule. Up to 81% of…
Experimente zur Zeolithbildung durch hydrothermale Umwandlung
1974
The formation of zeolites by hydrothermal alteration has been investigated by taking trass from the Laach volcanic area as a sample. Zeolites to be found are chabazite, phillipsite and analcime, all of which originated from the same phonolitic glass. This paper aims at explaining the formation of zeolites by means of experimental alteration of the pumice with various solutions. NaOH and KOH solutions were used in the experiments, these limited the formation conditions of chabazite, phillipsite, analcime in alkaline environments. Moreover, experiments were carried out with H2O dist and with solutions that formed during the alteration of pumice by reacting with H2O. These experiments were con…
The structure of charoite, (K,Sr,Ba,Mn)(15-16)(Ca,Na)(32)[(Si-70(O,OH)(180))](OH,F)(4.0)center dot nH(2)O, solved by conventional and automated elect…
2010
AbstractCharoite, ideally (K,Sr,Ba,Mn)15–16(Ca,Na)32[(Si70(O,OH)180)](OH,F)4.0·nH2O, a rare mineral from the Murun massif in Yakutiya, Russia, was studied using high-resolution transmission electron microscopy, selected-area electron diffraction, X-ray spectroscopy, precession electron diffraction and the newly developed technique of automated electron-diffraction tomography. The structure of charoite (a= 31.96(6) Å,b= 19.64(4) Å,c= 7.09(1) Å, β = 90.0(1)°,V= 4450(24) Å3, space groupP21/m) was solvedab initioby direct methods from 2878 unique observed reflections and refined toR1/wR2= 0.17/0.21. The structure can be visualized as being composed of three different dreier silicate chains: a d…
The beginning of western greek amphorae production in western Sicily: archaeometric and archaeological studies on 6th–5th centuries BCE amphorae manu…
2020
About 560 western Greek amphorae (6th–5th centuries BCE) re-used in enchytrismos burials were unearthed in the necropolis of the Dorian-Chalcidian colony of Himera in northwestern Sicily. Among the most striking issues is the determination of their geographical provenance. For this purpose, ceramic samples chipped from freshly broken surfaces of all the amphorae were first subdivided into macrofabrics by the use of a hand lens. Thereon, the samples were studied in accordance with standardized methods by the use of reflected light microscopy. Due to the special focus of our project on the characterization of Sicilian productions, a selection of amphorae which showed visible, macroscopic affi…
The lithium isotope response to the variable weathering of soils in Iceland
2021
Abstract This study has analysed Li isotopes ratios from well-studied soil and pore water profiles from Iceland that have the same parent material but have experienced different degrees of chemical weathering. Thus, from least to most weathered, we have analysed vitrosols (V), gleyic andosols (GA), brown andosols (BA), Histosols (H) and Histic Andosols (HA). Although the most weathered H and HA soils have the highest content in clay-sized material, they have the least fractionated δ7Lipore water values. In contrast, the least weathered GA and BA pore waters are most fractionated for Li isotopes. Given that Li isotope ratios are fractionated by clay mineral formation, this appears counter-in…
Interlamellar Reactions of Tetracalcium Aluminate Hydrates with Water and Organic Compounds
1967
Tetracalcium aluminate hydrates are the first example of layer-structured crystals containing neutral sheets, which are highly capable of interlamellar adsorption of water and neutral organic compounds. In this respect tetracalcium aluminate hydrates present new aspects of the phenomenon of swelling, and bring about the challenge of comparison with the frequently examined clay-organic compounds. This report is concerned with the probable monolayer structure of tetracalcium aluminate hydrate which forms five hydration stages. A summary concerning configuration and properties of adsorption complexes with approximately 500 selected organic substances follows. As far as these substances are hom…
Water uptake and equilibrium sizes of aerosol particles at high relative humidities: Their dependence on the composition of the water-soluble material
1978
Equilibrium water uptake and the sizes of atmospheric aerosol particles have for the first time been determined for high relative humidities, i.e., for humidities above 95 percent, as a function of the particles chemical composition. For that purpose a new treatment of the osmotic coefficient has been developed and experimentally confirmed. It is shown that the equilibrium water uptake and the equilibrium sizes of atmospheric aerosol particles at large relative humidities are significantly dependent on their chemical composition.
Modelling of thermo-chemical properties over the sub-solidus MgO–FeO binary, as a function of iron spin configuration, composition and temperature
2014
Thermo-chemical properties and T–X phase relations diagram of the (Mg,Fe)O solid solution are modelled using mixing Helmholtz energy, ΔF(T,x)mixing, calculated by quantum mechanical and semi-empirical techniques. The sub-solidus MgO–FeO binary has been explored as a function of composition, with iron either in high-spin (HS) or low-spin (LS) configuration. Only the HS model provides physically sound results at room pressure, yielding a correct trend of cell edge versus composition, whereas LS’s issues are at variance with observations. Mixing Helmholtz energy has been parametrized by the following relationship: ΔF(T,x)mixing = x × y × [U0(T) + U1(T) × (x – y) + U2(T) × (x − y)2]−T × S(x,y)c…