Jankovićite,Tl5Sb9(As,Sb)4S22, a new TI-sulfosalt from Allchar,Macedonia

Summary A hitherto unknown TI-sulfosalt, containing antimony and arsenic, was discovered by ore microscopy (including quantitative reflectance measurements) and electron microprobe analysis in samples from the Allchar TI-Sb-As sulfide ore deposit (Macedonia). The chemical formula is TI₅Sb₉(As,Sb)₄S₂₂, X-ray single crystal and powder diffration data gave the lattice parameters _o = 7.393(4) Å, b₀ = 8.707(2) Å, c_o = 17.584(3) Å, = 103.81(1)°, = 91.79(1)°, = 109.50(1)°; space group , Z = 1. The new mineral and the new mineral naine jankoviéite have been approved by the IMA/CNMMN.

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Jankoviit, Tl₅Sb₉(As,Sb)₄S₂₂, ein neues TI-Sulfosalz aus Allehar, Macedonien

Zusammenfassung Ein bislang unbekanntes Thallium-Antimon-Arsen-Sulfosalz wurde mittels Erzmikroskopie (inklusive quantitativer Reflexionsmessungen) und Elektronenstrahl-Mikrosonde in Proben aus der TI-Sb-As-Sulfid-Lagerstätte Allchar in Macedonien entdeckt. Die chemische Formel lautet Tl₅Sb₉(As,Sb)₄S₂₂, aus Röntgen-Einkristallaufnahmen und Pulverdiffraktogrammen konnten folgende Gitterkonstanten bestimmt werden: a_o = 7.393(4) Å, b_o = 8.707(2) _Å, c_o = 17.584(3) Å, a = 103.81(1)°, = 91.79(1)°, = 109.50(1)°; Raumgruppe , Z = 1. Das neue Mineral, sowie der neue Mineralname Jankoviit wurden durch die IMA/CNMMN anerkannt.

     

Surfactant production by marine phytoplankton

Electrochemical methods based on adsorption of organic molecules at the mercury electrode-solution interface were used to investigate surfactant production by marine phytoplankton. Six species of marine phytoplankton, representing the classes of Bacillariophyceae, Haeptophyceae, Chlorophyceae and Cryptophyceae, were studied in batch cultures.Our experimental results showed that surfactants were produced in culture media by healthy exponential growing cells. The measured response was found to depend on the particular species and the age of the culture.Total surfactant content in culture media generally increased with cell density, while surfactants per cell showed an inverse relation to cell density. However, we found that in Cryptomonas culture medium, during the exponential growth, excretion of the insoluble surfactant material per cell was independent of cell concentration.In addition to culture experiments, surfactant activity at several northern Adriatic stations was measured during various stages of phytoplankton bloom. It was concluded that a significant part of surfactant activity in a seawater column is due to phytoplankton production.     

Management of karst aquifers in Serbia for water supply

Karst aquifers represent one of the main sources of water supply in Serbia. Wide distributions of karstic areas, abundant reserves, and excellent quality of karst groundwater have been the reasons for its extensive use in water supply systems throughout the country. In Serbia, 70 karstic sources have been tapped for centralized water supply, with the assessed minimal capacity exceeding 4.5 m³/s. Most of the large cities of Eastern and Western Serbia currently use karst groundwater for water supply; however, due to unstable flow regime when only natural springflow is tapped, numerous problems arise during the recession period (summer–autumn). During the last two decades, after favorable conditions had been confirmed through hydrogeological survey and feasibility studies, several newly constructed systems for artificial control of karst aquifers (mostly in Eastern Serbia) resulted in significantly improved water supply.     

Improved bora wind simulation using a nested Eta Model

Summary In connection with a number of recent publications on anomalous (excessive) absorption of shortwave radiation (SWR) by clouds, the data of aircraft observations of spectral and total SWR vertical profiles in the troposphere obtained within the CAENEX, GAAREX and FGGE programmes have been discussed. These data demonstrated persuasively the existence of substantial SWR absorption by clouds in the visible wavelength region. In this context, the results of simulation numerical medelling of the SWR transfer in clouds have been considered. These show a significant enhancement of the SWR absorption by clouds due to an increase of the mean free path of photons under an impact of multiple scattering in clouds. Another important consideration may be the impact of SWR-absorbing pollutants in clouds, especially soot aerosols.With 4 Figures     

On some new statistical characteristics of the wind “Koshava”

Summary Koshava is a gusty wind of moderate to strong intensity, blowing from the south-eastern direction, over the area of the Republic of Serbia. It is caused by the interaction between the synoptic circulation and the orography of the Carpathian and the Balkan mountains. The Koshava wind can damage buildings, factories and industrial plants or city infrastructure. Therefore it is important to estimate its gust and the gustiness factor on the basis of the measured data.This paper discusses a statistical analysis of wind data in the maximum influence area of the Koshava wind in the periods of maximum duration of Koshava. The focus of the paper is the examination of urban and suburban effects on Koshava wind and the correlation between the instantaneous maximum wind speed and the hourly mean wind speed. The best fitting with various empirical distributions is proposed.With 10 Figures     

Paleozoic tectonostratigraphic units of the northwest and central Dinarides and the adjoining South Tisia

In the Central Dinarides and South Tisia different Paleozoic complexes occur in four geotectonic zones: (1) comparatively autochthonous units located in the cores of disrupted anticlines of the External Dinarides; (2) allochthonous disrupted units accompanied by more predominant Triassic formations in the Sava Nappe, which is thrust onto the northeastern margin of the External Dinarides; (3) allochthonous disrupted units, also together with Triassic formations, in the Pannonian and Durmitor nappes of the Internal Dinarides; and (4) polymetamorphic sequences in basement of the Pannonian Basin and South Tisia, respectively. This paper presents basic geological features for the main Paleozoic areas included in these four zones. The tectonostratigraphic units of the first two zones were related to the Gondwana passive continental margin, those of the third zone to the Paleotethyan oceanic realm, and those of Tisia to the active Laurussia margin. Geodynamic evolution of all these Paleozoic complexes was related to opening and closure of the Rheic and Paleotethys Oceans. Rifting processes along North Gondwana started in the Silurian, locally in the Cambrian-Ordovician, and were followed by the Late Silurian/Devonian opening of the Paleotethys. Subduction processes were active by the end of the Devonian and at the beginning of the Carboniferous along the Laurussia margin. They were followed during the Westphalian by main Variscan deformation during collision of Gondwana and Laurussia. Associated metamorphism was very low-grade in the Paleozoic units of the Sava Nappe, low-grade to epidote-amphibolite grade within the Paleozoic complexes of the Pannonian and Durmitor nappes in the Internal Dinarides, and poly-metamorphic with migmatites and granitoids in South Tisia. These processes gave rise to a Pangea stage with the Variscan basement disconformably overlain by Late Carboniferous and Permian sediments.     

Parallel micropetrographic and chemical studies of the solid degradation products from stepwise alkaline permanganate oxidation of a kerogen concentrate

The usefulness of parallel micropetrographic and chemical investigations to illustrate the nature of kerogen is demonstrated from data obtained in the study of the Aleksinac shale (Yugoslavia). To obtain more information about the chemical nature of kerogen, the stepwise oxidation with alkaline permanganate reported earlier has been modified and supplemented with micropetrographic and chemical investigations of partially degraded kerogen concentrates isolated from each degradation step. Five different types of particles were observed in kerogen concentrates. The results both of micropetrographic and of chemical investigations indicate a heterogeneity of the Aleksinac shale kerogen and a different reactivity of the particles observed.     

Rock mass mechanical characteristics in an opencut at bor copper mine

SummaryRock Mass Mechanical Characteristics in an Opencut at Bor Copper Mine Preliminary testing for the design of the new opencut, which will go to a depth of about 300 m, included testing rock mechanical characteristics. The character of the preliminary testing demanded by an engineering undertaking of this scale and the fundamental structural and physical properties of rock masses (fissuring, anisotropy, heterogeneity, natural stresses) are discussed and it is emphatically concluded that priority should go to in situ testing. Results are presented of determinations of the velocity of propagation of longitudinal elastic waves, elasticity modulus, coefficient of damage and shear strength parameters.With 7 Figures     

Transgressive overlap of a turbiditic sequence—priabonian of Ovče Pole,Macedonia

Flysch sequences develop normally from pelagic sediments, over a pre-flysch transitional unit, or from a well-developed transgressive base. A different situation has been observed in the western portion of the Upper Eocene flysch basin of Ov?e Pole, Macedonia, where deep-water turbidites appear almost directly over the eroded basement, transgressively overlapping the preexisting submarine relief. These relationships are explained as results of successive phases of subsidence in the basin. The outcrop area, situated between Titov Veles and Gradsko, represented a surface without deposition in the early depositional stages. Later subsidence introduced a turbiditic deposition into the domain without a break in sedimentation. Such cases may occur also in other flysch basins where lateral migration of the main depositional trough took place during the sedimentation.