Velibor Andrić

Non-destructive characterisation and classification of ceramic artefacts using pEDXRF and statistical pattern recognition

BackgroundPortable energy dispersive X-ray fluorescence (pEDXRF) spectrometry analysis was applied for the characterisation of archaeological ceramic findings from three Neolithic sites in Serbia. Two dimension reduction techniques, principal component analysis (PCA) and scattering matrices-based dimension reduction were used to examine the possible classification of those findings, and to extract the most discriminant features.ResultsA decision-making procedure is proposed, whose goal is to classify unknown ceramic findings based on their elemental compositions derived by pEDXRF spectrometry. As a major part of decision-making procedure, the possibilities of two dimension reduction methods were tested. Scattering matrices-based dimension reduction was found to be the more efficient method for the purpose. Linear classifiers designed based on the desired output allowed for 7 of 8 unknown samples from the test set to be correctly classified.ConclusionsBased on the results, the conclusion is that despite the constraints typical of the applied analytical technique, the elemental composition can be considered as viable information in provenience studies. With a fully-developed procedure, ceramic artefacts can be classified based on their elemental composition and well-known provenance.

Experimental and Theoretical Investigations of Cured and Uncured Disiloxane Bisbenzocyclobutene Thin Films

The main challenge in the large-scale commercial applications of benzocyclobutene (BCB) dielectrics is to perform their curing rapidly and efficiently at low temperatures, and in the same time, to obtain large area, high quality, pinhole free dielectric thin films. For that purpose, we investigated numerous uncured and cured BCB films, approximately 2 µm thick, spin-coated on glass/ITO surface, using optical and AFM microscopy, infrared (IR) and Raman spectroscopy, and complete these results with appropriate Linear Combination of Atomic Orbitals (LCAO) calculations. That way we relate microscopic characteristics of the involved molecules, and macroscopic properties of the cured and uncured polymers, which is important for their practical applications.

Ultrasound and shacking-assisted water-leaching of anions and cations from fly ash

Two mechanical extraction techniques were used for the extraction of environmentaly interesting components of coal fly ash: shaking, during which the extraction process lasted from 6 up to 24 h, and sonication that lasted from15 up to 60 min, using water as extractant. The concentration of anions in fly ash extracts was determined by ion chromatography, while atomic absorption spectrometry was used for determination of: As, Pb, Cd, Ni, Cr, Zn, Cu, Fe, Mn and Al. The ultrasonication yielded slightly higher amounts of extracted anions as well as Pb, Al, Mn and Fe cations, while shaking-assisted extraction was more efficient for the Cr, As, Zn and Ni ions. The changes in pH value, particle size distribution within colloid solution, zeta potential and conductivity during ultrasound-assisted extraction were measured in order to explain changes that occur on the surface of fly ash particles contacting water and different processes (adsorption, ion exchange and flocculation) that develop under natural conditions. Principal Component Analysis was used for assessing the effect of observed process parameters. It is essential to evaluate quantity of these elements leachable from coal fly ash into the surface waters in natural conditions in order to prevent contamination of the environment.

Analysis of Copper-Based Jewelry from the Site of Djerdap-Iron Gate on the Roman Limes

The location of workshop centres for manufacturing bronze objects in the territory of the Roman province of Upper Moesia, as well as of those in the area of Iron Gates limes on the Danube, still relies on hypotheses. Analyses were carried out on samples of the same type of objects from a number of sites near the Iron Gate in order to obtain reliable comparisons for the achieved results. The analyzed objects are: a crucible, ingots, fibulae (brooches), bracelets, and unfinished objects. The analyses and the presence of significant objects allow the conclusion that in this area existed a workshop.

Natural sepiolite efficiency in reducing 137Cs transfer and deposition into meat and edible organs of broiler chickens

The objectives of the present study were to examine the level of radiocesium deposit in meat and edible organs of broiler chickens as well as to investigate efficiency of natural sepiolite in reducing 137Cs deposition in meat, liver and gizzard of alimentary contaminated broiler chickens. Broiler chickens (six weeks of age) were fed with the standard diet and each broiler was given a single oral dose of 137Cs, total activity of 3750 Bq. The broilers were divided into two groups (10 broilers per group). The group 1 was control (received only radiocesium). The broilers of the group 2, in addition to radiocesium received natural sepiolite solution (2 g sepiolite per bird). After 24 hours, all broilers, from each group, were stunned and killed. The samples of meat, (breast and legs), liver and gizzard were taken from each broiler, for gamma spectrometry determination of radiocesium activity. After 24 hours of contamination, 56 % of introduced 137Cs radioactivity was deposited in the meat (breast and legs muscles), 1 % in the liver and 2,4 % in the gizzard of broiler chickens 42 days of age. Natural sepiolite demonstrated insufficient protective action. Compared to the control group, percentage reduction (decreasing percentage) of 137Cs deposition in meat was 16%, in liver 5% and in gizzard 12%.