Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 14
items per page: 25 50 75
Sort by:

Abstract

The extraction of mineral deposits is usually charged with additional taxes or royalty fees that go beyond the general income tax. As a rule, countries prefer stable sources of fiscal revenues based on the volume of raw material extraction, and investors prefer models based on profit tax, i.e. taking operating costs and risks lower than the expected profitability of the project into account. As a rule, too high a burden for the mining sector affects investors’ decisions regarding the introduction of new investments. There are a number of examples where excessive fiscal burdens force investors to move to countries with more favorable tax systems. An analysis of various forms of taxation of mining enterprises around the world has been presented and compared with the system implemented in Poland. Usually, the countries that apply the royalty fee in the mining sector at the same time introduce a number of adaptation mechanisms. This is crucial for new investments due to the fact that they may to some extent compensate for the high costs of transition from the investment to the operational phase. In most cases, several incentive mechanisms are used at the same time, e.g. the accelerated settlement of investment expenditures and the unlimited settlement of losses. The copper and silver mining tax introduced in Poland increased the discounted effective tax rate (ETR) from 38.5% to 89% for the entire investment period, which resulted in a 11-year return on investment, as well as a drop in the internal rate of return (IRR).There are currently no mechanisms in Poland which would balance the burden of this tax for a new investor. In order to balance the extraction tax for certain minerals in terms of the IRR and ETR key indicators, the introduction of several adaptation mechanisms has been proposed. For new investments the most essential mechanism is the preferential settlement of capital expenditures incurred in the pre-production phase of an investment. The others include accelerated amortization, the ability to deduct certain expenses for the exploration phase from the tax base, along with an extended tax loss settlement period, or a mechanism for deducting a certain percentage of investment expenses directly from the tax.
Go to article

Abstract

The article describes the impact of germanium on the course of surface phenomena in casting alloys of silver used in gold smithing. The aim of this works is to describe the assessment of resulting alloys, comparing the area of raw castings and the impact of the addition content of the alloy on the hardness of the samples. The evaluation also was subject to corrosion resistance of giving a comparison of their use in relations to traditional silver alloys.
Go to article

Abstract

For the reliable applications of silver nanowires, AgNW, which is used as a conductive transparent film in electronic devices, the isothermal degradation behaviors of AgNW films with and without overcoating were investigated. Accelerated isothermal degradation was performed as a function of temperature, time, and atmosphere. Electrical resistance and optical transmittance were measured and correlated with the microstructural damages, such as formation of oxide particles and fragmentations of AgNW, which were quantitatively determined from the scanning electron micrographs. The overcoating retarded the formation of oxide particles and subsequent fragmentations as well as resulting degradation in electrical resistance without affecting the optical transmittance.
Go to article

Abstract

Three plants extracts were used for biosynthesis of Ag nanoparticles (AgNPs). AgNPs nucleation process requires effective reduction agents which secure Ag+ to Ag0 reduction and also stabilizing/capping agents. The UV-vis and TEM observation revealed that the best results were obtained by R. officinalis leaf extract. The strong SPR band peak appeared at the wavelength 418 nm. Synthetized AgNPs were globular, fine (~20 nm), uniform and stabile throughout the experiment. A rapid rate of AgNPs synthesis was also significant and economically advantageous factor. Fine (10-20 nm) and globular nanoparticles were synthetized also by U. dioica leaf extract, but the stability of nanoparticles was not permanent. Despite V. vitis-idaea fruit extract contains a lot of reducing agents, UV-vis did not confirm the presence of AgNPs in solution. Synthetized Ag particles were very unstable, Ag particles agglomerated very fast and clearly indicated sediment was formed.
Go to article

Abstract

In 2011, the Miedzi Copper Corporation (MCC) initiated its exploration program involving deep Cu-Ag deposits in the Fore-Sudetic Monocline. A very vast study area was adopted, along with the use of a wide range of research instruments. In the years 2011–2013 the exploration of MCC involved 21 concession areas. The location of concessions for exploration as well as exploration and prospecting was based on the known prognostic and hypothetical areas with confirmed contact of the Rote Fäule facies with the reduced facies, placed in the proximity of the Zechstein elevations. In 2012 and 2013, historical boreholes drilled mainly by the petroleum industry were logged, and in cases where the preservation of rock material allowed, samples were collected for chemical analyses. Moreover, a wide range of specialized examinations was performed, involving organic chemistry, coal macerals, vitrinite reflectance and petrography, with a particular emphasis on the Rock Eval method. The latter allows the presence of the so-called strong Rote Fäule associated with the presence of the richest mineralized horizons to be established. It was equally important for the purpose of exploration to perform the reprocessing of geophysical data using the innovative method of effective reflection coefficients. This allows transforming a conventional seismic image into an impulse form of seismic records, meaning a temporal sequence of coefficients, whose sections can be correlated with the logs of historical boreholes in order to trace the course of lithological series. This method provides a much higher accuracy for determining structural elements crucial for exploration than before, suggesting the presence of various tectonic phenomena important for mineralization. As a result, a more detailed mineralization distribution model was obtained and the so-called sweet spots were pinpointed, becoming an object of further drilling exploration. The number of active concessions was reduced to 6, which resulted largely not just from the absence of ore, but also from economic premises. The drilling program initiated in 2013 and still continued today allowed the discovery and preliminary documentation of three copper and silver deposits in the Fore-Sudetic Monocline. These are the Mozów and Sulmierzyce deposits, where the presence of prospective areas was previously recorded, as well as the Nowa Sól deposit, discovered in the so-called green field, where no ore exploration was previously conducted. At the current stage of identification, each of these deposits contains resources exceeding 5 million tons of equivalent copper, and the performed economic analyses indicate the viability of their extraction using the modern methods of shaft sinking, air conditioning and waste management.
Go to article

Abstract

The subject of this article is the fragmentary silver plate of a gilded silver sheet braid ornament decorated with palmette motifs, which was deposited in the storage of the Gorgippia Archaeological Museum (Krasnodar Krai, Russia) in 2015, together with several other finds. The finds had been discovered at a site named Andreyevskaya Shhel, located a few kilometres south-east of the town, at the north-western hill area of the Caucasus. Among the artefacts deposited in the storage in 2015, there were other finds related to the 9–10th centuries (e.g. silver plate of a sabretache, gilded bronze belt mounts, bronze strap end, sabre, bow case or sabretache mount, fingering, etc). The braid ornament, with many analogies in the Carpathian Basin, could have reached the North Caucasian region by means of long-distance trade. This hypothesis is sustained by the considerable dirham-finds in the Carpathian Basin, which indicate the integration of this region – and of early Hungarian commerce as a whole – into the Eastern, Muslim trade network.
Go to article

Abstract

Layers of silver particles are used in the studies on pathophysiology and treatment of diseases, both in pre-clinical and clinical conditions. Silver layers can be formed using different techniques and on different substrates. Deposition by magnetron sputtering on glass beads was used in this study. Silver absorption by the body was estimated by calculating the difference in thickness of the silver nanolayer deposited on a bead and measured before and after application of the bead in an animal model of gastrointestinal inflammation. Recommendations for the minimal thickness of silver nanolayer deposited on glass beads were worked out for further studies.
Go to article

Abstract

Silver nanoparticles (AgNPs) are widely used in numerous industries and areas of daily life, mainly as antimicrobial agents. The particles size is very important, but still not suffi ciently recognized parameter infl uencing the toxicity of nanosilver. The aim of this study was to investigate the cytotoxic effects of AgNPs with different particle size (~ 10, 40 and 100 nm). The study was conducted on both reproductive and pulmonary cells (CHO-9, 15P-1 and RAW264.7). We tested the effects of AgNPs on cell viability, cell membrane integrity, mitochondrial metabolic activity, lipid peroxidation, total oxidative and antioxidative status of cells and oxidative DNA damage. All kinds of AgNPs showed strong cytotoxic activity at low concentrations (2÷13 μg/ml), and caused an overproduction of reactive oxygen species (ROS) at concentrations lower than cytotoxic ones. The ROS being formed in the cells induced oxidative damage of DNA in alkaline comet assay. The most toxic was AgNPs<10 nm. The results indicate that the silver nanoparticles, especially less than 10 nm, may be harmful to the organisms. Therefore, risk should be considered when using nanosilver preparations and provide appropriate protective measures when they are applied.
Go to article

Abstract

In August 2016, tomato plants grown during a hot, wet summer with heavy soil flooding, displaying symptoms of wilting, dead plant, root rot with crown and stem rot, at Beni Suef and Fayoum governorates were examined. A number of 16 fungal isolates were isolated from tomato plants displaying the above symptoms. These isolates were classified as belonging to six species, namely: Alternaria solani, Chaetomium globosum, Fusarium solani, Fusarium oxysporum, Pythium spp. and Rhizoctonia solani. Isolates of Pythium spp. were prevalent and were found to be more pathogenic than the other fungal isolates. This species causes damping-off, root rot, sudden death, stem rot and fruit rot. The pathogen was identified as Pythium aphanidermatum based on morphological, cultural, and molecular characteristics. Biogenic silver nanoparticles (AgNPs) were produced using the F. oxysporum strain and characterized by transmission electron microscopy (TEM). The size of these spherical particles ranged from 10 to 30 nm. In vitro, biogenic AgNPs showed antifungal activity against P. aphanidermatum. In greenhouse and field experiments, AgNPs treatment significantly reduced the incidence of dead tomato plants due to root rot caused by P. aphanidermatum compared to the control. All of the investigated treatments were effective and the treatment of root dipping plus soil drenching was the most effective. To the best of our knowledge, this study describes P. aphanidermatum on tomato in Egypt for the first time. Also, biogenic AgNPs could be used for controlling root rot disease caused by this pathogen.
Go to article

Abstract

In 2009, in the village of Wysoczany, Sanok district, Podkarpackie voivodeship, a silver coin was accidentally found. This coin is a tetradrachm. It has irregular oval shape and is plano-convex. It is not well preserved, i.e. it has poorly legible depictions on both sides, which significantly impedes its typological classification, and thus its precise dating. The dimensions of the coin are: 27.5 × 28.5 mm and its weight is: 11.83 g (after conservation works). In the case of the described here coin there are no clear analogies and, therefore, there is no certainty to what type it should be attributed. This paper attempts to analyse a few of the existing possibilities. One of the taken into consideration is the south-eastern direction, i.e. Geto-Dacian mintage or Celtic Geto-Dacian one. Some similarities can be found in the following types: Agriş A — Şilindia, Ramna, and also in the category referred to as “the other types” according to the typology by C. Preda. The other possible direction is the central Celtic mintage associated with Boii. However, none of the examples presented in this paper is a close analogy to the coin from Wysoczany. Therefore, its typological attribution as well as its dating remain to be an open question.
Go to article

Abstract

The research focuses on assessing the metal content, mainly copper, lead, iron and also silver in metallurgical slag samples from the area where historical metallurgical industry functioned. In the smelter located in Mogiła, near Krakow (southern Poland), whose operation is confirmed in sources from 1469, copper was probably refined as well as silver was separated from copper. Based on the change of chemical and soil phase content and also taking cartographic and historical data into account, considering the restrictions resulting from the modern land use the area was determined whose geochemical mapping can point to the location of the 15th century Jan Thurzo’s smelter in Mogiła near Krakow. Moreover, using the same approach with the samples of this kind here as with hazardous waste, an attempt has been made to assess their impact on the environment. Thereby, taking the geoenvironmental conditions into account, potential impact of the industrial activity has been assessed, which probably left large scale changes in the substratum, manifested in the structure, chemical content and soil phase changes. Discovering areas which are contaminated above the standard value can help to identify historical human activities, and finding the context in artefacts allows to treat geochemical anomalies as a geochronological marker. For this purpose the best are bed sediments, at present buried in the ground, of historical ditches draining the area of the supposed smelter. Correlating their qualities with analogical research of archeologically identified slags and other waste material allows for reconstructing the anthropopressure stages and the evaluation of their effects. The operation of Jan Thurzo’s smelter is significant for the history of mining and metallurgy of Poland and Central and Eastern Europe.
Go to article

Abstract

Triploid viviparous onions [Allium x cornutum Clementi ex Visiani 1842, syn Allium cepa L. var. viviparum Metzg. (Alef.), auct.] (2n = 3x = 24), are known in some countries only as rare relict crops. In other parts of the world they are still traditionally or even commercially cultivated. In previous cytogenetic studies of the Croatian triploid viviparous onion Ljutika, Giemsa C-banding, chromosome pairing analysis during meiosis, and genomic hybridization in situ indicated a complex hybrid with highly heterozygous karyotype structure, with possible triparental genome organization. This study continues an analysis of the karyotype structure of Ljutika. Staining with fluorochromes CMA3 (Chromomycin A3) and Dapi (4,6-diamidino-2-phenylindole) confirmed previous results from Giemsa C-banding and revealed GC-rich heterochromatic regions associated mainly with chromosome ends and nucleolus organizing regions (NORs), and only a few interstitial bands. Fish mapping of the ribosomal 18S-5.8S-26S genes revealed two major rDNA signals on the short arms of two subtelocentric satellite chromosomes in almost all metaphase plates of Ljutika. The largest subtelocentric chromosome lacked rDNA signals. A significantly smaller rDNA signal was occasionally located on one small submetacentric chromosome. These results are in agreement with previously published results from identification of NORs by silver-staining technique, which confirmed a maximum three nucleoli in interphase nuclei. We discuss the molecular mechanisms underlying rearrangements and activity of ribosomal genes in the triploid karyotype.
Go to article

This page uses 'cookies'. Learn more