An attempt at assessing the correlation between the content of fluoride in the Antarctic krill from various fishery and its.biological condition was carried out Fluoride was determined with the Dolan method, which was modified by the present authors. No statistically significant correlation was found between the degree of sexual maturity and fluoride content. There was no decisive statistical relation between the body weight and body length of individuals and the content of fluoride in the Antarctic krill.
Using gas chromatography methods the content of DDT residues was determined in the tissues of 4 species of Antarctic birds: Oceanites oceanicus, Catharacta skua, Sterna vittata and Larus dominicanus, and in the eggs of Macronectes giganleus and Larus dominicanus. Samples were collected on King George Island, in February and October 1978. The highest level of DDT and its metabolites concentration was observed in the tissues of Oceanites oceanicus and the lowest in the tissues of Sterna vittata and in the eggs of M. giganteus and L. dominicanus. The differences in DDT content between different species and within one species are associated with their food composition and winter migrations to the regions with higher degree of DDT pollution.
Eggs and samples of the fat (blubber), muscles, and liver from three species of penguins: Pygoscelis adeliae, P. antarctica and P. papua were collected on King George Island in 1978. DDT residues were determined in the samples with the gas chromatography method. In the tissues pp'DDE and traces of pp'DDT were found, in the eggs merely pp'DDE. The highest DDT content (wet weight) was recorded in the fat of penguins, the lowest in the eggs. The differences between species in the mean values of the content of DDT residues in the tissues and eggs are not statistically significant. An increase in the level of pp'DDE concentration in the tissues and eggs of penguins was observed, as compared with earlier studies of other authors, as well as a tendency toward dippearance of the active form, i.e. pp'DDT, in the samples.
The new investigation method of the kinetics of the gas emission from moulding sands used for moulds and cores is presented in this
paper. The gas evolution rate is presented not only as a function of heating time but also as a function of instantaneous temperatures. In
relation to the time and heating temperature the oxygen and hydrogen contents in evolving gases was also measured. This method was
developed in the Laboratory of Foundry Moulds Technology, Faculty of Foundry Engineering, AGH. Gas amounts which are emitted from
the moulding sand at the given temperature recalculated to the time unit (kinetics) are obtained in investigations. Results of investigations
of moulding sand with furan resin are presented - as an example - in the paper.
In this research reactive powder concrete (RPC) was prepared using sand from North Sinai. The mechanical properties of locally cast RPC were investigated and evaluated by studying the effects of using different cement and silica fume contents and new steel fi bers’ aspect ratios as reinforce-ment for RPC. Specimens’ preparation, curing regimes and testing procedures to evaluate the com-pressive strength, the modulus of elasticity, the indirect tensile strength and the fl exural strength were discussed. A compressive strength of 154.5 MPa, indirect tensile strength of 11.98 MPa, mod-ulus of elasticity of 45.1 GPa and fl exural strength of 30.26 MPa have been achieved for reinforced RPC contains 800 kg/m³ cement content and silica fume content 30% of cement weight. The test results showed some improvements by increasing cement and silica fume contentsas well as adding steel fi bers on the compressive strength, modulus of elasticity and indirect tensile strength.
In recent years, more and more attention has been paid to the quality of produced coal size categories for energy purposes. This is important from the perspective of promoting clean coal technologies which aim at changing the perception of coal as a fuel friendly for the environment. This is specifically because hard coal resources in Poland allow the national energy security to be guaranteed on the basis of energy production based on hard coal. Fine coals upgraded at coal processing facilities in the separation process in fine coal jigs are mainly used in energy production from coal. In the article, an analysis of hard coal upgrading in a jig regarding the optimum recovery of a useful fraction in the concentrate (combustible and volatile matter) and non-useful fraction in tailings (ash and sulfur) was conducted. Based on the industrial testing of a fine coal jig, the granulometric and densimetric analysis of the taken samples of concentrate, middlings and tailings of coal was conducted in laboratory conditions. Yields of products were calculated in separated size-fractions of separation products, and ash content and total sulfur content were determined in them. Based on the results of granulometric, densimetric and chemical analyses of the obtained size-fractions, the balance of separation products and appropriate calculations, Fuerstenau upgrading curves which allowed the process to be evaluated and a comparison of the results of hard coal upgrading regarding the optimum recovery of the organic phase in the concentrate and mineral components in tailings to be drawn. The obtained results were evaluated on the basis of different criteria for changing the device’s hydrodynamic operational conditions. The ash content and total sulfur content were analyzed as non-useful substances.
Irrigation of cultivated plants can be a source of toxic lithium to plants. The data on the effect of lithium uptake on plants are scant, that is why a research was undertaken with the aim to determine maize ability to bioaccumulate lithium. The research was carried out under hydroponic conditions. The experimental design comprised 10 concentrations in solution differing with lithium concentrations in the aqueous solution (ranging from 0.0 to 256.0 mg Li ∙ dm-3 of the nutrient solution). The parameters based on which lithium bioretention by maize was determined were: the yield, lithium concentration in various plant parts, uptake and utilization of this element, tolerance index (TI) and translocation factor (TF), metal concentrations in the above-ground parts index (CI) and bioaccumulation factor (BAF). Depression in yielding of maize occurred only at the highest concentrations of lithium. Lithium concentration was the highest in the roots, lower in the stems and leaves, and the lowest in the inflorescences. The values of tolerance index and EC50 indicated that roots were the most resistant organs to lithium toxicity. The values of translocation factor were indicative of intensive export of lithium from the roots mostly to the stems. The higher uptake of lithium by the above-ground parts than by the roots, which primarily results from the higher yield of these parts of the plants, supports the idea of using maize for lithium phytoremediation.
The paper deals with the problem of multiple remelting influence on AlSi6Cu4 alloy modified by antimony on chosen mechanical characteristics, microstructure and gas content. This foundry alloy is used mostly in automotive industry. Foundry Aluminum-Silicon alloys are also used in number of industrial weight sensitive applications because of their low weight and very good castability and good mechanical properties. Modifiers are usually added to molten aluminum-silicon alloys to refine the eutectic phase particle shape and improve the mechanical properties of the final cast products and Al-Si alloys cast properties.
Time of concentration, Tc, is defined as time elapsed from the beginning of rainfall infiltrated into soil layer until it reaches a constant infiltration rate (fc) which is indicated an equilibrium subsurface flow rate. In hydrological view, time of concentration plays a significant role in elaboration of transformation of rainfall into runoff in a watershed. The aims of this research are to define influence of soil density and soil water content in determining time of concentration using infiltration concept based on water balance theory, and to find out the effect of land slope this time. Watershed laboratory experiment using rainfall simulator was employed to examine time of concentration associated with infiltration process under different slope, soil density and soil water content based on water balance concept. The steady rainfall intensity was simulated using sprinklers which produced 2 dm3∙min–1. Rainfall, runoff and infiltration analysis were carried out at laboratory experiment on soil media with varied of soil density (d) and soil water content (w), where variation of land slopes (s) were designed in three land slopes 2, 3 and 4%. The results show that relationship between soil density and land slope to time of concentra-tion showed a quadratic positive relationship where the higher the soil density address to the longer time of concentration. Moreover, time of concentration had an inverse relationship with soil water content and land slope that means time of con-centration decreased when the soil water content increased.
Trinexapac-ethyl is one of the newest growth regulators used in agriculture and horticulture. As a most growth retardants it acts by inhibiting gibberellin (GA) biosynthesis. A field study was conducted to determine the effects of trinexapac-ethyl on growth of winter wheat. Trinexapac ethyl was used alone (75 g a.i./ha and 125 g a.i./ha) and in the mixture with chlorocholine chloride (50 g a.i./ha + 675 g a.i./ha) at the 2nd node stage. Trinexapac-ethyl and its mixture with CCC activity was weather dependent. Their influence on the crop was strictly related to the temperature and rainfall during an individual year of trials. Plant growth regulators much more influenced winter wheat plants in abundant rainfall and higher temperature conditions. Lodging was not observed during the experiment.
This article presents changes in the operating parameters of a combined gas-steam cycle with a CO2 capture installation and flue gas recirculation. Parametric equations are solved in a purpose-built mathematical model of the system using the Ebsilon Professional code. Recirculated flue gases from the heat recovery boiler outlet, after being cooled and dried, are fed together with primary air into the mixer and then into the gas turbine compressor. This leads to an increase in carbon dioxide concentration in the flue gases fed into the CO2 capture installation from 7.12 to 15.7%. As a consequence, there is a reduction in the demand for heat in the form of steam extracted from the turbine for the amine solution regeneration in the CO2 capture reactor. In addition, the flue gas recirculation involves a rise in the flue gas temperature (by 18 K) at the heat recovery boiler inlet and makes it possible to produce more steam. These changes contribute to an increase in net electricity generation efficiency by 1%. The proposed model and the obtained results of numerical simulations are useful in the analysis of combined gas-steam cycles integrated with carbon dioxide separation from flue gases.
The results presented in this paper are a continuation of the previously published studies. The results of hest treatment of ductile iron with
content 3,66%Si and 3,80% Si were produced. The experimental castings were subjected to austempering process for time 30, 60 and 90
minutes at temperature 300o
C. The mechanical properties of heat treated specimens were studied using tensile testing and hardness
measurement, while microstructures were evaluated with conventional metallographic observations. It was again stated that austempering
of high silicone ferritic matrix ductile iron allowed producing ADI-type cast iron with mechanical properties comparable with standard
ADI.
Ductile iron casts with a higher silicone content were produced. The austempering process of high silicone ductile iron involving different
austempering times was studied and the results presented. The results of metallographical observations and tensile strength tests were
offered. The obtained results point to the fact that the silicone content which is considered as acceptable in the literature may in fact be
exceeded. The issue is viewed as requiring further research.
We measured the total chlorophyll (Chl a+b) content in seedling leaves of fifteen maize cultivars infested by two studied aphid species (oligophagous Rhopalosiphum padi L., monophagous Sitobion avenae F.) 7 and 14 days after the beginning of infestation, using a SPAD-502 chlorophyll meter. Chlorophyll loss was more severe in R. padi-infested than in S. avenae-infested plants. Chlorophyll depletion was greater after long-term (14 days) than after short-term aphid infestation in the investigated host systems. Seedlings of Złota Karłowa and Tasty Sweet were more damaged by aphid feeding; Ambrozja and Płomyk plants were less damaged by aphid feeding.