Analysis of weld joints made of titanium alloy GRADE 2 produced by electron beam welding

Selected properties of welded joints of 2 mm thick titanium alloy Grade 2 produced by different welding parameters of electron beam welding were investigated. The visual inspection, macro and micro analysis, tensile strength test and microhardness measurements were performed. Samples manufactured by appropriate welding parameters had no internal defects, heat-affected zone (HAZ) was narrow and transformation from α phase to β phase was observed in this area. The failure occurred in the base metal during tensile test, while maximum ultimate tensile strength reached 454,3 MPa

Axial light emission and Ar metastable densities in a parallel plate dc micro discharge in steady state and transient regimes

Axial emission profiles in a parallel plate dc micro discharge (feedgas: argon; discharge gap d=1mm; pressure p=10Torr) were studied by means of time resolved imaging with a fast ICCD camera. Additionally, volt-ampere (V-A) characteristics were recorded and Ar* metastable densities were measured by tunable diode laser absorption spectroscopy (TDLAS). Axial emission profiles in the steady state regime are similar to corresponding profiles in standard size discharges (d=1cm, p=1Torr). For some discharge conditions relaxation oscillations are present when the micro discharge switches periodically between low current Townsend-like mode and normal glow. At the same time the axial emission profile shows transient behavior, starting with peak distribution at the anode, which gradually moves towards the cathode during the normal glow. The development of argon metastable densities highly correlates with the oscillating discharge current. Gas temperatures in the low current Townsend-like mode (T= 320-400K) and the high current glow mode (T=469-526K) were determined by the broadening of the recorded spectral profiles as a function of the discharge current.Comment: submitted to Plasma Sources Sci. Techno

Playing with fire: Exploring ceramic pyrotechnology in the Late Neolithic Balkans through an archaeometric and experimental approach

Addressing ceramic pyrotechnology plays a key role in understanding a wide range of cultural and social behaviours associated to pottery production. Firing is the process which transforms clay into ceramic, which is one of the most frequently preserved materials in the majority of Neolithic and later archaeological sites. Though firing temperatures and the functions of various pyrotechnological installations have been extensively investigated in archaeology, both have often been addressed separately. Most of our knowledge on firing structures and procedures in the Neolithic are still largely based on ethnoarchaeological evidence. To move forward, we need to consider all aspects involved in ancient pyrotechnology, together with use of additional investigative tools. This study aims to address Neolithic pottery firing from a diverse perspective that merges archaeometric analyses and experimental archaeology. To demonstrate the potential of this approach, we combined an archaeometric case study of pottery from the late Neolithic (5200–4800 BCE) from the site of Gradište-Iđjoš (Serbia) with experimental pit firings, likely one of the mostly frequently employed firing techniques used in prehistoric periods. Scientific analyses include X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), and ceramic petrography. These methods were run on both archaeological materials and experimental reproductions. Additionally, a detailed program of firing temperature monitoring, integrated observations on atmospheric conditions, soaking time, and duration were recorded to contribute to the study. The experiments enabled us to collect results useful for our understanding of the pyrotechnological knowledge of Neolithic potters from a technological and social point of view. In addition, they demonstrated the potential of a dedicated methodological framework for studying pottery firing that can be applied to other chronological and cultural contexts

A Two-Field Formulation for Surfactant Transport within the Algebraic Volume of Fluid Method

Surfactant transport plays an important role in many technical processes and industrial applications such as chemical reactors, microfluidics, printing and coating technology. High fidelity numerical simulations of two-phase flow phenomena reveal rich insights into the flow dynamics, heat, mass and species transport. In the present study, a two-field formulation for surfactant transport within the algebraic volume of fluid method is presented. The slight diffuse nature of representing the interface in the algebraic volume of fluid method is utilized to track the concentration of surfactant at the interface as a volumetric concentration. Transport of insoluble and soluble surfactants is investigated by tracking two different concentrations of the surfactant, one within the bulk of the liquid and the other one at the interface. These two transport equations are in turn coupled by source terms considering the ad-/desorption processes at a liquid-gas interface. Appropriate boundary conditions at a solid-fluid interface are formulated to ensure surfactant conservation, while also enabling to study the ad-/desorption processes at a solid-fluid interface. The developed numerical method is verified by comparing the numerical simulations with well-known analytical and numerical reference solutions. The presented numerical methodology offers a seamless integration of surfactant transport into the algebraic volume of fluid method, where the latter has many advantages such as volume conservation and an inherent ability of handling large interface deformations and topological changes

Utilisation des dents de sagesse en prothetique stomatologique mobile et fixe

Ustaljeno je mišljenje da su umnjaci veoma slabi zubi, da su podložni karijesu i da zbog toga na njih ne treba mnogo računati. To je verovatno i razlog što se literatura o njima, posebno sa protetskog aspekta, veoma retko sreće. Sa druge strane, protetičar se u svakodnevnoj praksi veoma često sreće sa kompleksom problema, koji prati jedno ili obostrano terminalnu krezubost. Iz ovog razloga, autori su prihvatili analizu problema terminalne krezubosti i eventualno njihovo rešenje očuvanjem i korišćenjem umnjaka, bilo u fiksnoj bilo u mobilnoj stomatološkoj protetici. Radeći na ovom problemu, autori su došli do zaključka, da umnjacimi treba posvetiti punu pažnju u punoj mladosti. Ovo se može postići ako se umnjacima omogući pravilno i potpuno izrastanje i ako se eventualni karijozni procesi blagovremeno saniraju.I\u27t is an established opinion that wisdom teeth are very weak teeth, that they are subject to caries and therefore one should not count on them too much. This is probably the reason that very little mention is made of wisdom teeth in the literature, especially in works dealing with prosthetic aspects. On the other hand the dental surgeon engaged in prosthetic work very often encounters a complex problem in his daily practice accompanying uni- or bilateral terminal tooth gaps. For this reason the authors have gone into an analysis of the problems of terminal tooth gaps and their possible solution by preservation and use of the wisdom toth either in fixed or mobile stomatologic prosthetics. Working at this problem the authors arrived at the conclusion that full attention ought to be devoted to the wisdom teeth in early youth. This may be achieved if regular and complete development of the wisdom teeth is made possible and if any likely carious processes are treated on time.L\u27opinion courante est que les dents de sagesse sont tres faibles et fragiles, qu\u27elles presentent une disposition ä la carie et qu on ne peut done beacoup compter sur el les. C\u27est certainement pour cette raison que la litteratüre dentaire, au point de vue prothetique, n\u27est pas tres riche ä se sujet. D\u27autre part, le prothetiste rencontre tres souvent, dans la pratique quotidienne, de nombreux et complexes problemes causes par les breches terminales de I\u27arc dentaire, unilaterales ou bilaterales. C\u27est pourquoi les auteurs se sont penches, sur lanalyse des breches terminales et ont envisage la solution eventuelle qu\u27offrira\u27it la conservation des dents de sagesse et leur utilisation dans les protheses mobiles ou fixes. En etudiant le probleme les auteurs sont pairvenus ä la conclusion qu\u27il faut apporter la plus grande attention aux dents de sagesse des I\u27adolescence, assurer ä eel les — ci une croissance complete et reguliere et soigner ä temps les caries eventuelles

Genetic variability of pheasant (Phasianus spp) in breeding station Ristovača

One of the possible reasons for pheasant population number decline in past several years might be loss of adaptability in populations originated from breeding stations caused by inbreeding depression. Due to fact that adaptability is a consequence of genetic structure of the populations, the aim of this paper was the analysis of genetic variability in pheasant population from breeding station Ristovaca using molecular markers. Allozyme variability of 20 putative gene loci was detected by polyacrylamide gel electrophoresis. Polymorphism was revealed in 5 loci: Est-1, Pgd, Sod, Gpi-2 and Odh. The values of genetic variability measures - heterozigosity polymorphism, fixation indices and H/P ratio indicate low level of genetic variability and possible presence of inbreeding depression within pheasant population

Contact process in a wedge

We prove that the supercritical one-dimensional contact process survives in certain wedge-like space-time regions, and that when it survives it couples with the unrestricted contact process started from its upper invariant measure. As an application we show that a type of weak coexistence is possible in the nearest-neighbor ``grass-bushes-trees'' successional model introduced in Durrett and Swindle (1991).Comment: 11 pages, 4 figure

Spectroscopic investigation of two Serbian icons painted on canvas

A multianalytical study of two Serbian icons, The Virgin and Child and St. Petka, painted on canvas by unknown authors was performed in order to identify the materials used as pigments, binders and the ground layer. The investigated icons belong to the Museum of the Serbian Orthodox Church in Belgrade. Samples, collected from different parts of the icons, were analysed by: optical microscopy (OM), energy dispersive X-Ray fluorescence (EDXRF), Fourier transform infrared (FTIR) and micro-Raman spectroscopy. The obtained results revealed the presence of the following pigments: Prussian Blue, ultramarine, Green Earth, iron oxides, Lead White and Zinc White. Linseed oil was used as the binder. The materials used for the ground layers were gypsum, calcite, baryte and Lead White. The gilded surface of the icon The Virgin and Child was made of gold. The gilded surface on the frame of this icon was made of imitation of gold, i.e., Schlagmetal, since EDXRF spectroscopy showed the presence of copper and zinc, while gold was not detected. Based on the style and the consideration of an art historian, as well as on the obtained results for the corresponding pigments and binder, both icons were most probably made at the end of 19th or the beginning of the 20th century

Physicochemical characterisation of pottery from the Vinca culture, Serbia, regarding the firing temperature and decoration techniques

A study of decorated Neolithic pottery samples from the excavation site Plocnik, Serbia, was performed using X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR) and X-ray fluorescence (XRF) spectroscopy. The investigated samples belong to the era of the Vinca culture that existed in the central Balkan region from the mid VI until the first half of the V millennium BCE. The mineralogical composition of the pottery samples and comparison of the investigated pottery with thermally treated local clay indicated firing temperatures in the range from 600 to 800 degrees C. Two different types of white pigments were identified in white incrusted decorations: calcium carbonate and bone white (composed of crushed bones). This is the first evidence of the use of bones for decorations in pottery of the Vinca culture from the excavation site Plocnik. In addition to this, it was revealed that the potters used the iron reduction technique for obtaining black decorations

А medieval burial from the site of Сupska: an anthropological and contextual analysis of the skeletal remains from grave 1

In 1956, the Institute of Archaeology and the National Museum in Belgrade carried out excavations at the site of Supska, near Ćuprija, in Central Serbia. Based on the material culture findings, the site is mostly known as a Late Neolithic one; however, archaeological findings from other periods were discovered too. In the 1956 excavations, the cultural layers, and archaeological features with the Vinča culture archaeological materials were examined, as well as one grave, marked as Grave 1. The results of this excavation have been previously published in one monograph; however, an anthropological analysis of the individual found in Grave 1 has not been conducted before. In this paper, we present the results of contextual, bioanthropological, stable isotopes and C14 analyses of human skeletal remains found in Grave 1. The results showed that a young adult, who had experienced nonspecific metabolic stress during childhood, as evidenced by traces of linear enamel hypoplasia and porotic hyperostosis, was buried in this grave. AMS date revealed that this individual lived between 1280–1390 cal. AD, while the results of the stable isotope analyses suggested that it had mixed diet based on C4 plants (such as millet) and/or C3 plants, with larger amounts of animal protein, possible deriving from freshwater fish