210 research outputs found
Pottery production at the mesolithic site of Kabbashi Haitah (central Sudan) : an integrated morphological, petrographic and mineralogical analysis
This paper presents the results of an interdisciplinary archeometric study on Early Mesolithic pottery from the prehistoric site of Kabbashi Haitah, located 35 km north of Khartoum (central Sudan), along the Nile Valley. A large set of potsherds, selected after a preliminary macroscopic analysis of 1075 fragments representing the various vessels (mainly plain and globular in shape, with various rim diameter), macrofabrics and decoration types (either with or without incised or stamped decorations, i.e. incisedwavy line and rocker stamp) was analysed to define the type of the raw materials used and their manufacturing technology. The mineralogical and petrographic features, determined by optical microscopy and X-ray powder diffraction, indicate that the pottery was produced using an illitic clay tempered with quartz and/or K-feldspar derived from granite/syenite grinding, and fired in the temperature range between 750 and 900 degrees C
Pesi da telaio romani dalla Venetia fra archeologia, epigrafia e archeometria
As a part of a project conducted by the University of Padua on the wool production in the Roman Venetia, the paper focuses on a group of loom weights found in the late nineteenth century near Castagnaro (Verona). The integrated analysis (archeology, epigraphy and archaeometry) conducted on the loom weights allow to reflect on the marking of the loom weights and on the organization of the production in a Roman figlina.Nel quadro di un Progetto sulla lavorazione della lana nella Venetia romanacondotto dall’Università di Padova, il contributo presenta i risultati di un’analisi integrata fra archeologia, epigrafia e archeometria relativamente a una serie di pesi da telaio rinvenuti a fine Ottocento presso Castagnaro (Verona). I manufatti, con buona probabilità prodotti in una stessa fornace, offrono l’occasione per una riflessione sulla bollatura di tale categoria di oggetti e sull’organizzazione del lavoro nelle figlinae romane
Production Technologies of Ancient Bricks from Padua, Italy: Changing Colors and Resistance over Time
Representative and very uneven texturally bricks having yellow/beige or pale or dark red
colors from the Renaissance walls (16th century) of Padua, Northeast Italy, were studied by means of
colorimetric, petrographic (MOP), chemical (XRF), mineralogical (PXRD) and microstructural analysis
(FESEM-EDS). Starting from the color measurements of the ceramic bodies, the manufacturing
technologies and their influence on the physical behavior and durability of the bricks were established.
The porous system was characterized by means of hygric tests and mercury intrusion porosimetry;
the compactness and structural anisotropy were defined through ultrasound velocity; the uniaxial
compressive strength was determined; and durability to salt crystallization and frost action of the
bricks was assessed. Mg- and Ca-rich illitic clays fired at temperatures ≥900 ◦C were used to
manufacture the beige hue bodies, while the pale red bricks were made out with Ca- and Fe-rich illitic
clays fired at 850–900 ◦C. A lower carbonate content on the base clays and a lower firing temperature
were the main causes responsible for the changing colors from beige to red hue. The increase of the
red color was associated to higher silicate inclusions content and lower development of reaction rims
around grains. The low sintering degree achieved yielded highly porous bodies with diverse porous
systems, leading to differential physical performance and durability of the bricks that may turn out
beneficial for the conservation of the historic walls.Marie Sklodowska-Curie grant agreement No 836122CLAYONRISK ProjectResearch Group of the Junta de AndalucÃa RNM179MSC Actio
Degradation processes of reinforced concretes by combined sulfate--phosphate attack
A novel form of alteration due to the interaction between hydrated cement phases and sulfate and phosphate-based pollutants is described, through the characterization of concrete samples from an industrial reinforced concrete building. Decalcification of the cement matrices was observed, with secondary sulfate and phosphate-based mineral formation, according to a marked mineralogical and textural zoning. Five alteration layers may be detected: the two outermost layers are characterized by the presence of gypsum–brushite solid solution phases associated with anhydrous calcium sulfates and phosphates, respectively, while a progressive increase in apatite and ammonium magnesium phosphates is observable in the three innermost layers, associated with specific apatite precursors (brushite, octacalcium phosphate and amorphous calcium phosphate, respectively). The heterogeneous microstructural development of secondary phases is related to the chemical, pH and thermal gradients in the attacked cementitious systems, caused by different sources of pollutants and the exposure to the sun's radiation
Clayey materials for traditional bricks production in North-Eastern Italy through a combined compositional study: From firing dynamics to provenance
The compositional study of two main types of clayey materials outcropping nearby Padua (Veneto region, north-eastern Italy) and bricks used in historical constructions of the city is here addressed. Mineralogically, the clayey materials are illitic-chloritc clays, both non-carbonatic and carbonatic/highly-carbonatic clays, that chemically correspond to clays with important contents of silica and/or iron and of calcium and/or magnesium, respectively. Two main type of historic bricks were produced: i) one using mixtures of illitic/illitic-chloritic clays with abundant quartz and of carbonatic clays and firing temperatures between 950 and 1000 °C, and ii) a second one made out of illitic-chloritic clays non-carbonatic and fired around 850–900 °C. The comparative analysis between the mineralogical changes occurred in the clayey materials with increasing temperatures and the mineral assemblages detected in the studied bricks have provided evidences about the mixture of raw clays, that could be in turn compositionally similar to those analysed. The development of aluminium and magnesium-calcium silicates and/or magnesium silicates during the firing was fostered by mixing such base clays, giving rise to very durable and highly calcareous bricks. Whereas titanium and the trace elements zircon, vanadium, chromium and zinc may entail markers of provenance of illitic-chloritic clays quarried in the area, the strontium may represent a geochemical fingerprint for constraining supply areas of carbonatic clays. The compositional analysis carried out through the combined use of X-Ray Powder Diffraction (XRPD) and X-Ray Fluorescence Spectrometry (XRF) has provided data regarding to the composition and provenance of the starting clays as well as procedures and firing dynamics adopted for the manufacturing of the traditional bricks in the city of Padua from Roman Times to Renaissance.European Union’s Horizon 2020
Research and Innovation Programme under the Marie Sklodowska-Curie
Individual Fellowship (grant agreement No 836122)Research Group of the Junta de AndalucÃa, Spain (RNM179
Late Pleistocene/Early Holocene Evidence of Prostatic Stones at Al Khiday Cemetery, Central Sudan
The recovery of three stone-like ovoid objects within the burial of a pre-Mesolithic (Late Pleistocene/Early Holocene) individual at Al Khiday cemetery (Central Sudan) raises the question of the nature and origin of these objects. The position in which the objects were found in relation to the human skeleton suggested a pathological condition affecting the individual, possibly urinary bladder, kidney stones or gallstones. To solve this issue, a multi-analytical approach, consisting of tomographic, microstructural and compositional analyses, was therefore performed. Based on their microstructure and mineralogical composition, consisting of hydroxylapatite and whitlockite, the investigated stones were identified as primary (endogenous) prostatic calculi. In addition, the occurrence of bacterial imprints also indicates on-going infectious processes in the individual. This discovery of the earliest known case of lithiasis extends the appearance of prostatic stones into the Late Pleistocene/Early Holocene, a disease which therefore can no longer be considered exclusive to the modern era, but which also affected prehistoric individuals, whose lifestyle and diet were significantly different to our own
Wild Food:Plants, Fish and Small Animals on the Menu for Early Holocene Populations at al-Khiday, Central Sudan
Al Khiday, located on the bank of the White Nile in Sudan, offers an exceptionally preserved stratigraphic sequence, providing a unique opportunity to use organic residue analysis to investigate diet and subsistence over the full course of the Khartoum Mesolithic together with possible continuity or change into the Early Neolithic, a period of nearly 3000 years (8900-6000 cal BP). Whilst the vast and diverse Mesolithic fish assemblage indicates a strong reliance on products from aquatic habitats, floodplains, vegetated marshes and open water, results from the lipid residue analysis suggest that the fish were not cooked in the pots, likely being consumed in other ways. Rather, pots were more specialised in processing plants, wild grasses, leafy plants and sedges, confirmed by experimental analysis, and for the first time, providing direct chemical evidence for plant exploitation in the Khartoum Mesolithic. Non-ruminant fauna, such as warthog and low lipid-yielding reptiles such as Adanson’s mud turtle and Nile monitor lizard, which were found in significant numbers at al-Khiday, were also cooked in pots. There is little evidence for the processing of wild ruminants in the pots, suggesting either that ruminant species were not routinely hunted, or, that large wild fauna may have been cooked in different ways, possibly grilled over fires. These data suggest sophisticated economic strategies by sedentary people likely exploiting their ecological niche to the fullest. Pottery use changes considerably in the Early Neolithic, with ruminant products being more routinely processed in pots, and while the exploitation of domesticates cannot be confirmed by a small faunal assemblage, some dairying does take place. In summary, our results provide valuable information on Early and Middle Holocene lifeways in central Sudan
Critical behavior and phase diagrams of a spin-1 Blume-Capel model with random crystal field interactions: An effective field theory analysis
A spin-1 Blume-Capel model with dilute and random crystal fields is examined
for honeycomb and square lattices by introducing an effective-field
approximation that takes into account the correlations between different spins
that emerge when expanding the identities. For dilute crystal fields, we have
given a detailed exploration of the global phase diagrams of the system in
plane with the second and first order transitions, as well
as tricritical points. We have also investigated the effect of the random
crystal field distribution characterized by two crystal field parameters
and on the phase diagrams of the system. The system exhibits
clear distinctions in qualitative manner with coordination number for
random crystal fields with . We have also found that,
under certain conditions, the system may exhibit a number of interesting and
unusual phenomena, such as reentrant behavior of first and second order, as
well as a double reentrance with three successive phase transitions.Comment: 19 pages, 17 figure
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