A TORQUE OF EARLY ROMAN TIME FROM KALINOVO (KALININGRAD REGION, RUSSIA): THE COMPOSITION OF ENAMEL AND DATA ON CHRONOLOGY AND ORIGIN

В статье рассмотрен химический состав и техника нанесения красной эмали гривны, производной от типа Хавор, происходящей из могильника Калиново самбийско-натангийской культуры (Калининградская обл.). Гривна датирована второй половиной I - второй третью II в. н. э. Установлено, что эмаль была изготовлена по «кельтскому» рецепту с высоким содержанием меди и свинца. Однако если состав в данном случае является скорее хронологическим, чем культурноопределяющим признаком, то его сочетание с техникой нанесения эмали (в прорезные углубления-насечки) заставляет искать прототипы данного украшения среди образцов кельтского эмальерного ремесла. Данные о хронологии и технологической традиции, в которой изготовлена гривна, полученные на основании стилистического анализа и состава эмали, хорошо согласуются с результатами комплекса исследований, посвященных данной находке. The article considers the chemical composition and technique of applying the red enamel on the torque derived from the Havor type, originating from the cemetery of Kalinovo of Sambian-Natangian culture (Kaliningrad region). The torque dates back to the second half of I - second third of II c. AD. The enamel was produced using «Celtic» recipe with high copper and lead content. The composition of the enamel in this case is rather chronological than a culturally determining indication. However, its combination with the technique of enamelling (in the slotted recessing notches) gives grounds to search for the prototypes of this decoration among the samples of the Celtic enamel craft. The data on the chronology and technological tradition in which the torque was made, obtained on the basis of stylistic analysis and data on the enamel composition, well agree with the results of a comprehensive studies of this find.

Production of Thin PbxSn1–xTe Films by “Hot Wall” Method for Creating IR-Photodetectors

Alloys of lead and tin telluride (PbxSn1–xTe) are materials with good thermoelectric properties, as well as semiconductors that can be used as long-wave infrared detectors. Polycrystalline telluride of PbxSn1–xTe (0.05 £ x £ 0.80) alloys has been synthesized by direct fusion technique. Thin films of these materials have been obtained by the hot wall method depositing Сorning 7059 on glass substrates at Tsub = (200–350) oC and vacuum of about 10–5 Torr. The microstructure of the films has been investigated by XRD, SEM and EDX methods. The X-ray spectra of thin films have been in satisfactorily agreement with the spectra of the powder target and indicated the absence of binary phases. The films have shown a natural cubic crystalline structure. While increasing the lead content, the unit cell parameter of the crystal also increases. The established linear relationship between the unit cell parameter and the elemental composition corresponds to Vegard's law. The SEM analysis has shown that the films are polycrystalline, have a columnar structure, are tightly packed and have good mechanical adhesion. The grain size depends on the chemical composition and temperature of the substrate. The electrical measurements have shown that the grown films are non-degenerate semiconductors of p-type conductivity. The conductivity of the films was in the range of σ = (3 × 101)–(1 × 104) Ω–1×cm–1. An increase of lead concentration leads to a decrease in electrical conductivity. Hall mobility in the grown thin films increases in the range of changes in the lead content from ~10 to ~23 at. %, and decreases with a further increase to ~33 at. %. At the same time, the strongest dependence of the decrease in mobility on an increase in temperature increase is observed for films with a high lead content and is explained by the predominant scattering of charge carriers by vibrations of the crystal lattice. For a sample with an average lead concentration, an alternative effect of two scattering mechanisms is observed in the temperature dependence of the mobility: by impurity ions and by phonons.

Jatropha integerrima, Duranta erecta and Hibiscus rosa-sinensis as Potential Lead Absorbent from Polluted Air in Dense Traffic Area

Lead (Pb) is one of the contaminants found in polluted air, especially in the area with dense traffic. Herbaceous plants are potentially used to reduce the Pb content in the polluted air. This study was designed to evaluate the potential of several plants, such as Jatropha integerrima, Duranta erecta and Hibiscus rosa-sinensis, as Pb absorbents from polluted air based on Pb accumulation and chlorophyll levels. The lead content was measured using atomic absorption spectrophotometry (AAS), while the chlorophyll content was tested using spectrophotometers at wavelengths of 649 nm and 665 nm. Results showed that the three plant species had potential as Pb absorbents from the air. The highest lead content was found from J. integerrima at 1.293 mg/kg, followed by H. rosa-sinensis at 1.232 mg/kg and D. erecta at 0.840 mg/kg. On the other hand, the highest level of leaf chlorophyll content was H. rosa-sinensis at 16.116 mg/kg, followed by D. erecta L. at 12.594 mg/kg and J. integerrima Jacq. of 10.297 mg/kg. No correlation was found between the Pb level and chlorophyll content of the three plants. It can be concluded that the three herbaceous plants have potential as Pb absorbents in the polluted air.

Numerical Simulations of 22% Efficient All-Perovskite Tandem Solar Cell Utilizing Lead-Free and Low Lead Content Halide Perovskites

Lead-free or low lead content perovskite materials are explored in photovoltaic devices to mitigate the challenges of toxic lead-based halides. However, the conversion efficiency from such materials is far below compared to its counterparts. Therefore, to make a humble contribution in the development of lead-free or low lead content perovskite solar cells (PSCs) for future thin-film photovoltaic (PV) technology, a simulation study of tin (Sn) and Pb mixed halide (MAPb0.5Sn0.5I3, 1.22 eV) PSC is carried out in this manuscript. The device is further optimized in terms of transport layer and thickness variation to get 15.1% conversion efficiency. Moreover, the optimized narrow bandgap halide (NBH) based device is further deployed in the monolithic tandem configuration with lead-free wide bandgap (1.82 eV) halide, i.e., Cs2AgBi0.75Sb0.25Br6, 1.82eV (WBH) PSC, to mitigate the thermalization as well as transparent Eg losses. Filtered spectrum, current matching, and construction of tandem J-V curve at the current matching point are utilized to design the tandem solar cell under consideration. Tandem device delivered short current density, JSC (15.21 mA.cm-2), open-circuit voltage, VOC (1.95 V), fill factor, FF (74.09 %) and power conversion efficiency, PCE (21.97%). The performance of the devices considered in this work is found to be in good approximation with experimental work.

Lead Concentration in Dust Fall in Zahedan, Sistan and Baluchistan Province, Iran

Dust is one of the atmospheric pollutants that has adverse environmental effects and consequences. Dust fall contains particles of 100 microns and smaller which fall from the atmosphere onto the earth surface. The aim of this study is to determine the concentration of lead in dust fall samples in order to study the pollution level of this element in Zahedan, Sistan and Baluchistan Province, Iran. Therefore, sampling was carried out using 30 marble dust collectors (MDCO) for 3 months in the spring of 2015 to investigate the quantitative variation and spatial analysis of lead content in dust fall. These dust collectors were placed at 30 stations on the buildings' roofs with a height of approximately 1.5 meters across the city. According to the results, the mean lead concentration in the spring was 90.16 mg/kg. In addition, the zoning map of lead content shows that the lowest level of lead was measured at Imam Khomeini station, while Mostafa Khomeini station had the highest amount of lead.

Proximate Compositions and Risk Assessment of Lead in Two Common Fishes (Labeo rohita and Barbonymus gonionotus) Collected from River and Farms of Bagerhat, Bangladesh

Background: Among the local fish species in Bangladesh, Labeo rohita and Barbonymus gonionotus are two popular fish species. The present work focused on proximate compositions (moisture, protein, fat, and ash) and risk assessment of lead in two common fishes (L. rohita and B. gonionotus) collected from river and farms of Bagerhat, Bangladesh. Furthermore, effect of freezing condition on fish lipid was studied. Methods: Proximate compositions of the fish samples were determined according to conventional methods. The lead contents were analyzed by wet digestion method using an atomic absorption spectrophotometer. The health risks models such as Estimated Daily Intake (EDI), Target Hazard Quotient (THQ), Hazard Index (HI), and Target Cancer Risk (TCR) were conducted for health risk assessment of the local people. Data were analyzed using SPSS software (version 16.0). Results: A positive correlation was found between moisture-protein and lipid-ash of the L. rohita fish. Besides, a positive relation was observed in ash-moisture, and lipid-protein for B. gonionotus. The lead content in river L. rohita, farm L. rohita, river B. gonionotus, and farm B. gonionotus was observed as 9.00, 9.20, 8.29, and 6.39 mg/kg, respectively. The lead content found in the fish species were above the permissible limit. The TCR revealed the carcinogenic effects to the local people due to exposure of lead. Conclusion: This study reflects some data about proximate values of L. rohita and B. gonionotus fishes. The concentrations of lead in the fish samples were above the safe limits, and may have carcinogenic effects of the local consumers in Bagerhat, Bangladesh.

Lead concentration in dust fall in Zahedan, Sistan and Baluchistan Province, Iran

Dust is one of the atmospheric pollutants that have adverse environmental effects and consequences. Dust fall contains particles of 100 microns or even smaller ones, which fall from the atmosphere onto the earth surface. The aim of this study is to determine the concentration of lead in dust fall samples in order to study the pollution level of this element in Zahedan, Sistan and Baluchistan Province, Iran. Therefore, sampling was carried out using 30 marble dust collectors (MDCO) for 3 months in the spring of 2015 to investigate the quantitative variation and spatial analysis of lead content in dust fall. These dust collectors were placed at 30 stations on the building roofs with a height of approximately 1.5 meters across the city. According to the results, the mean lead concentration in the spring was 90.16 mg/kg. In addition, the zoning map of lead content shows that the lowest level of lead was measured at Imam Khomeini station while the highest amount of lead appeared in Mostafa Khomeini station.