The normotensive (Wistar) and spontaneously hypertensive (SHR) rats were examined to assess the response of the organism to selenium (Se) overdose. Moreover, the effect of zinc (Zn) and vitamin E, i.e. dietary components interacting in many biochemical processes with Se, on the Se uptake was evaluated. The control group was fed an untreated diet, and the diets of two other groups were overdosed with Se in the form of sodium selenite (9 mg/kg) and supplemented with Zn (13 mg/kg). Two experimental groups were fed a diet supplemented with Zn (13 mg/kg) and Se at an adequate level (0.009 mg/kg); a half of the animals was supplemented with vitamin E. The results showed significant differences in the Se contents between the rat strains in case of Se-overdosed groups, where in the liver and kidney tissue Se contents of SHR rats exceeded 3- and 7-fold the normotensive ones. The Se uptake was altered by the vitamin E; no effect of Zn was observed. Activities of antioxidant enzymes were determined in the animal tissues indicating different patterns according to rat strain, tissue analysed, and administered Se dose. Thus, Se overdose, for instance, via an incorrectly prepared dietary supplement, can result in serious imbalances of the biochemical status of the animals.
Concentrations of four trace elements, copper (Cu), zinc (Zn), manganese (Mn) and seleni- um (Se), have thus far proven to be affected by lentiviral infections in people and rhesus monkeys. As small ruminant lentivirus (SRLV) infection is responsible for one of the most important goat diseases, caprine arthritis-encephalitis (CAE), we evaluated serum and liver concentrations of Cu, Zn, Mn, Se in goats severely affected by symptomatic CAE and compared them with litera- ture reference intervals. Serum and liver samples of dairy goats euthanized due to severe clinical form of CAE were collected and screened for the concentration of Cu, Zn, Mn (54 serum sam- ples, 22 liver samples), and Se (36 serum samples, 22 liver samples) using flame atomic absorption spectrometry for Cu, Zn, Mn and graphite furnace atomic absorption spectroscopy for Se. In both serum and liver samples concentration of Zn was the highest, followed by Cu concentration, and then by Mn and Se. There was no relationship between serum and liver concentrations of trace elements. Liver concentrations of all four trace elements and serum Cu concentration fell within literature reference intervals, although liver Se concentration was mainly in the lower marginal range (between 0.4 and 1.0 mg/L). Serum Zn concentration was elevated (>1.2 mg/L) in all goats, serum Mn concentration was elevated (>0.04 mg/L) in 42 (78%) goats and serum Se concentra- tion was elevated (>1.6 mg/L) in 13 (36%) goats. Concluding, severe symptomatic CAE does not appear to be associated with the level of any of the four trace elements.
Zinc concentrations in apices [Zn 2+]apex of the lichens, Cladonia arbuscula and C. rangiferina were determined along transects through two sub-Arctic towns in the Usa River Basin, northeast European Russia. One transect, which was 130 km long running in an east-west direction, passed through the town of Vorkuta and the other transect, which was 240 km long running in a southwest-northeast direction, passed through Inta. Zinc accumulation in lichens, which was detected 25-40 km within the vicinity of Vorkuta, was largely attributed to local emissions of alkaline coal ash from coal combustion. The present results using C. arbuscula around Vorkuta are consistent with those of previous studies suggesting that this lichen is a useful bioindicator for trace metals. There was no such elevation of [Zn 2+]apex detected in C. rangiferina along the transect running through Inta.
The article presents the results of research which describes antagonism between Pb-Zn in selected plant species from the area of Czestochowa – Mirow district (north-western part of the Czestochowa Upland). There were analyzed changes in the ratio of Pb/Zn in different organs of the tested plants as a function of the Zn content changes. The content of metals in the plants and the soil was determined using atomic absorption spectrophotometry AAS. In all organs of the plants there was observed antagonistic decrease of Pb uptake and accumulation, resulting from the increase in the concentration Zn. Antagonism between Zn and Pb in roots of the tested plants occurred at Zn content of 200–600 μg/g. In turn, antagonism in stems and flowers occurred at lower contents of zinc (100–180 μg/g). In leaves, antagonism between Pb and Zn occurred when Zn was present at the level of 300–800 μg/g. Ex definition of the analyses confirm the presence of antagonism of lead with regard to high levels of Zn. The study also confirmed that the degree of antagonism depends on the plant species.
Oxide fraction of industrial zinc ash from hot dip galvanizing was characterized in terms of composition and leaching behaviour in 10% sulfuric acid solution. Waste product contained about 68% Zn, 6% Cl, 3% Al, 1% Fe, 0.7% Si, 0.5% Pb and minor percentages of other metals (Mn, Cu, Ti etc.). It consisted mainly of zinc oxide contaminated with metallic zinc, zinc hydroxide chloride and silica. Dissolution of the metals from the material was determined as a function of solid to liquid ratio (50-150 kg/m3), temperature (20°C and 35°C) and agitation rate (300 and 900 rpm). The best results (50 g/dm3 Zn(II) at 78% zinc recovery) were obtained for 100 kg/m3 and the temperature of 20°C. Increase in the agitation rate had weak effect on the zinc yield. The final solutions were contaminated mainly by Fe(II, III) ions. Leaching of the material was an exothermic process with the reaction heat of about 800 kJ/kg.
The article presents the results of studies on the rate of zinc evaporation in the atmosphere of helium and carbon monoxide (II) carried out with the thermogravimetric method. The estimated values of zinc streams were compared with the values determined based on theoretical relationships.
In the present study, the effects of 10, 20, 30 ppm hormone mixtures (indole-3-acetic acid + gibberellic acid + kinetin) with 0.1, 0.3, 0.5 and 1 ppm zinc (Zn) concentrations alone and their mixtures on the cambial activity of sour cherry (Cerasus vulgaris Miller) cuttings were investigated. Morphological and anatomical developments of the plants were observed. The leaves of the plants treated with zinc were found to be greener than the control. Plants treated with zinc faded earlier than the control. The cambial zone thickness, the cambial zone cell line, the radial and tangential lengths of the cambial zone cells decreased with increasing concentrations of zinc and increased with increasing concentrations of hormones. The radial and tangential wall widths of the cambial zone cells increased with increasing zinc concentrations and decreased with increasing hormone concentrations. As a result, in the 0.1, 0.3, 0.5 and 1 ppm Zn concentrations, the cambial zone thickness decreased by 10, 28, 50 and 65%, respectively, compared to the control. Thirty ppm hormone mixture – H.M. (indole-3-acetic acid + gibberellic acid + kinetin) increased the cambial zone thickness by 65, 15, 5% in 0.1, 0.3 and 0.5 Zn, respectively, compared to the control. It was found that plant hormones importantly improved the harmful effects of zinc on the cambial activity of the plant cuttings.
An analysis of the effect of drawing speed on the formation of a zinc coating in the multi-stage fine steel wire drawing process has been carried out in the article. Pre-hardened 2.2 mm-diameter material was drawn into 1.00 mm-diameter wire in 6 draws on a multi-stage drawing machine. The drawing process was carried out at a drawing speed of 5, 10, 15, 20 and 20 m/s, respectively. Mechanical tests were tests were performed for the final wires to determine their yield strength, ultimate tensile strength, uniform and total elongation and reduction in area. The thickness of the zinc coating on the wire surface was determined by the gravimetric method and based on metallographic examination. The use of electron scanning microscopy, on the other hand, enabled the identification of individual phases in the zinc coating. The above investigations were supplemented with corrosion testing of 1.00 mm-diameter wires. It has been demonstrated that drawing speed significantly influences not only the thickness of the zinc coating on the drawn wire surface, buts also its morphology and corrosion resistance.
Dust generated at an electric arc furnace during steel production industry is still not a solved problem. Electric arc furnace dust (EAF) is a hazardous solid waste. Sintering of well-prepared briquetted mixtures in a shaft furnace is one of possible methods of EAFD utilisation. Simultaneously some metal oxides from exhaust gases can be separated. In this way, various metals are obtained, particularly zinc is recovered. As a result, zinc-free briquettes are received with high iron content which can be used in the steelmaking process. The purpose of the research was selecting the appropriate chemical composition of briquettes of the required strength and coke content necessary for the reduction of zinc oxide in a shaft furnace. Based on the results of the research the composition of the briquettes was selected. The best binder hydrated lime and sugar molasses and the range of proper moisture of mixture to receive briquettes of high mechanical strength were also chosen and tested. Additionally, in order to determine the thermal stability for the selected mixtures for briquetting thermal analysis was performed. A technological line of briquetting was developed to apply in a steelworks.
This paper analyses the heat treatment of the hot-dip zinc coating deposited on both cast iron and steel. The aim of research is to increase coating hardness and wear resistance without decreasing its anticorrosion properties. Hot-dip zinc coating was deposited in industrial conditions (acc. PN-EN ISO 10684) on disc shape samples and bolts M12x60. The achieved results were assessed on the basis of microscopic observation (with the use of an optical and scanning microscope), EDS (point and linear) analysis and micro-hardness measurements. It was discovered that the heat treatment of zinc coating results in an increase in hardness which is caused by the corresponding changes in microstructure.
The subject of the paper is structural stability of the Zn-26 wt.% Al binary alloys doped with 2.2 wt.% Cu or 1.6 wt.% Ti addition. The structural stability of Zn-Al alloys with increased Al content is connected with stability of solid solution of zinc in aluminium α', which is the main component of these alloys microstructure. Such a solution undergoes phase transformations which are accompanied, among others, by changes in dimensions and strength properties. The structural stability of the ZnAL26Cu2.2 and ZnAl26Ti1.6 alloys was investigated using XRD examinations during long term natural ageing after casting, as well as during long term natural ageing after super-saturation and quenching. On the basis of the performed examinations it was stated that small Ti addition to the binary ZnAl25 alloy, apart from structure refinement, accelerates decomposition of the primary α' phase giving stable structure in a shorter period of time in comparison with the alloy without Ti addition. Addition of Ti in amount of 1.6 wt.%, totally replacing Cu, allows obtaining stable structure and dimensions and allows avoiding structural instability caused by the metastable ε−CuZn4 phase present in the ZnAl26Cu2.2 alloy.
Studies were conducted on a zinc coating produced on the surface of ductile iron grade EN-GJS-500-7 to determine the eutectic grain effect. For this purpose, castings with a wall thickness of 5 to 30 mm were made and the resulting structure was examined. To obtain a homogeneous metal matrix, samples were subjected to a ferritising annealing treatment. To enlarge the reaction surface, the top layer was removed from casting by machining. Then hot dip galvanising treatment was performed at 450°C to capture the kinetics of growth of the zinc coating (in the period from 60 to 600 seconds). Analysing the test results it was found that within the same time of hot dip galvanising, the differences in the resulting zinc coating thickness on samples taken from castings with different wall cross-sections were small but could, particularly for shorter times of treatment, reduce the continuity of the alloyed layer of the zinc coating.
The paper presents relationships between the degree of structure fineness and feeding quality of the Al – 20 wt.% Zn (Al-20 Zn) alloy cast into a mould made from sand containing silica quartz as a matrix and bentonite as a binder, and its damping coefficient of the ultrasound wave at frequency of 1 MHz. The structure of the examined alloy was grain refined by the addition of the refining Al-3 wt.% Ti – 0.15 wt.%C (TiCAl) master alloy. The macrostructure analysis of the initial alloy without the addition of Ti and the alloy doped with 50-100 ppm Ti as well as results of damping experiments showed that the structure of the modified alloy is significantly refined. At the same time, its damping coefficient decreases by about 20-25%; however, it still belongs to the so called high-damping alloys. Additionally, it was found that despite of using high purity metals Al and Zn (minimum 99,99% purity), differences in the damping coefficient for samples cut from upper and bottom parts of the vertically cast rolls were observed. These differences are connected with the insufficient feeding process leading to shrinkage porosity as well as gases present in metal charges which are responsible for bubbles of gas-porosity.
The paper is devoted to grain-refinement of the medium-aluminium zinc based alloys (MAl-Zn). The system examined was sand cast Zn10 wt. %. Al binary alloy (Zn-10Al) doped with commercial Al-3 wt. % Ti – 0.15 wt. % C grain refiner (Al-3Ti-0.15C GR). Basing on the measured attenuation coefficient of ultrasonic wave it was stated that together with significantly increased structure fineness damping decreases only by about 10 – 20%. The following examinations should establish the influence of the mentioned grain-refinement on strength and ductility of MAl-Zn cast alloys.
The subject of this study is the presentation of relation between the degree of structure fineness and ultrasonic wave damping coefficient for the high-zinc aluminium alloys represented in this study by the sand mould cast alloy Al - 20 wt% Zn (AlZn20). The studied alloy was refined with a modifying (Al,Zn)-Ti3 ternary master alloy, introducing Ti in the amount of 400 pm into metal. Based on the analysis of the initial and modified alloy macrostructure images and ultrasonic testing, it was found that the addition of (Al,Zn)-Ti3 master alloy, alongside a significant fragmentation of grains, does not reduce the coefficient of ultrasonic waves with a frequency of 1 MHz.
The effect of cationic, anionic and nonionic surface active additives, organic compounds and polymers on the electrodeposition of Zn-Mo coatings on steel substrate and detailed characterization in chosen optimal conditions was studied. The influence of polyethylene glycol (PEG) various concentration, sodium dodecyl sulphate (SDS), triton X-100, d-sorbitol, cetyl trimethyl ammonium bromide (CTAB), thiourea and disodium ethylenediaminetetraacetate (EDTA) on the electrodeposition process was examined. The composition of deposits was defined by wavelength dispersive X-ray fluorescence spectrometry (WDXRF). Results has shown that the current efficiency of the electrodeposition of Zn-Mo coatings is 71.4%, 70.7%, 66.7% for 1.5 g/dm3 PEG 20000, 0.1 g/dm3 Triton X-100 and 0.75 M D-sorbitol respectively. The surface topography and roughness of selected coatings on steel was investigated by atomic force microscopy (AFM). The attendance of D-sorbitol of 0.75 M in the solution cause clear reduction of grain size and the value of roughness parameter (Ra) in relation to SDS, PEG, Triton X-100 and the sample prepared without the additives. The morphology of electrodeposited layers was studied by scanning electron microscopy (SEM). The addition of selected additives to the electrolytic bath results in the formation of smoother, brighter and more compact Zn-Mo coatings in comparison to layers obtained from similar electrolytes but without the addition of surfactants. The optimal concentration of the most effective additives such as PEG 20000, Triton X-100 and D-sorbitol is 1.5 g/dm3, 0.1 g/dm3, 0.75 M respectively.
Water mint (Mentha aquatica L.) belongs to the arsenic tolerant plant species suitable for cultivation in Central European climate conditions. Therefore, its possible application for remediation of contaminated soil was investigated in pot and field experiments. Two M. aquatica plants of different origin, i) commercially market-available mint plants, and ii) plants habituated at the arsenic contaminated former mining area in southern Tuscany (Italy) were tested for their arsenic uptake, transformation, and speciation. The total arsenic concentrations in the experimental soils varied from 21 to 1573 mg As kg-1, the mobile fractions did not exceed 2% of total soil arsenic. The mint plants originating from the contaminated area were able to remove ~400 µg of arsenic per pot, whereas the commercial plant removed a significantly lower amount (~300 µg of arsenic per pot). Only arsenite and arsenate, but no organoarsenic compounds were identified in both stems and leaves. Arsenate was the predominant arsenic compound and reached up to 80% regardless of the origin of the mint plants. Although M. aquatica seems to be able to grow in contaminated soils without symptoms of phytotoxicity, its efficiency to remove arsenic from the soil is limited as can be demonstrated by total elimination of As from individual pots not exceeding 0.1%. Moreover, the application of plants originating from the contaminated site did not result in sufficient increase of potential phytoextraction efficiency of M. aquatica. Although not suitable for phytoextraction the M. aquatica plants can be used as vegetation cover of the contaminated soil at the former mining areas
This work presents the results of a study whose aim was to determine the influence of algal blooms on precipitation of heavy metals. The scope of the study covered culture of a mixed population made up of Scenedesmus and Pseudokirchneriella algae in experimental conditions and initiating a metal biosorption process with the use of culture biomass by administering ions of Zn(II) and Ni(II). The process was controlled by assessing the level of biosorption of metals entered at a one-off basis in the form of Zn(II) and Ni(II) salts or in the form of mixture of both ions, in comparison to the control sample, at different exposure times (2 hours and 24 hours). The presence of metals was determined both in the biomass and in the culture medium. The presented results of the study confirm the effectiveness of Chlorophyta in the process of zinc and nickel biosorption. A phenomenon of competitiveness between the metals was observed when they were administered at the same time.
The aim of this study was to determine the effect of different zinc and iron concentrations in culture medium on growth and development of maize and wheat seedlings in terms of their inoculation with bacteria of Azospirillum genus. Maize and wheat in vitro cultures were inoculated, respectively, by strains of Azospirillum lipoferum and Azospirillum brasilense strains. The experimental factor was the supplementation of the culture medium with zinc (25, 200 and 600 mg·kg-1 of the medium) and iron (25, 200 and 600 mg·kg-1 of the medium). Counts of bacteria from the Azospirillum genus were analysed and plant seedling growth and development as well as the content of chlorophyll in plant leaf blades were monitored. Zinc turned out to reduce strongly numbers of bacteria of the Azospirillum genus. Azospirillum brasilense turned out to be particularly sensitive to elevated levels of this chemical element in the environment. The negative influence of increased quantities of zinc on cereal seedlings became apparent only after the application of the highest concentrations of this metal in the medium (600 mg·kg-1), while quantities which did not exceed 200 mg·kg-1 exerted a stimulation effect on the mass of maize and wheat seedlings. Iron added to the culture medium in quantities which did not exceed 200 mg·kg-1 did not reduce numbers of bacteria of the Azospirillum genus; on the contrary, they stimulated their growth. However, at higher concentrations, this metal turned out to exert a strong negative impact on the chlorophyll content in leaf blades as well as on the mass of maize and wheat seedlings. The inoculation with bacteria of the Azospirillum genus exerted a positive influence on the mass increase of maize and wheat seedlings and increased chlorophyll concentrations in leaf blades. At the same time, it contributed significantly to limiting or even levelling out the toxic impact of zinc and iron during the initial phases of plant growth and development.
The article presents the results of plasma vitrification of solid remnants from thermal waste treatment with and without the addition of a carbonate fraction obtained from lead-zinc ore flotation. The substrates used in the research were slags and ashes from medical waste treatment, incineration of municipal waste, sewage sludge as well as hazardous and industrial wastes. The plasma treatment resulted in acquiring products of different quality depending on the processed substrate. Most of the obtained products were of vitreous and homogenic build. Treatment of remnants from incineration of hazardous and industrial wastes resulted in obtaining heterogeneous and rough surfaced products. A 20% share of the carbonate fraction enabled the obtaining of a vitrified product with a glassy surface and fracture. Hardness of the obtained products was rated in Mohs scale and ranged from 6 to 6,5. Leaching tests showed a decrease in heavy metal concentration in the leachates from vitrificates with the addition of carbonate fraction compared to the ones with it.
The paper presents the research results of the solenoid housing made of the Zn4Al1Cu alloy that was destroyed as a result of corrosion. Surface of the tested part showed macroscopically the features typical for white corrosion, and the resulting corrosion changes led to a disturbance of the alloy cohesion. The research performed have shown that the tested solenoid valve has intergranular corrosion as a reaction of the environment containing road salt. The corrosion was initiated in the areas of the alfa phase existence appearing in the eutectic areas which propagated over dendritic areas of the alloy. Initiation of the corrosion followed as a result of the galvanic effect of the alfa phase reach in aluminium showing higher electrochemical potential, in contact with the eta phase reach in zinc. The impact of the phase reach in lead present in the microstructure on the corrosion processes run was not found.
The paper presents results of measuring attenuation coefficient of the Al-20 wt.% Zn alloy (AlZn20) inoculated with different grain refiners. During experiments the melted alloys were doped with Al-Ti3-C0.15 refining master alloy. Basing on measurements performed by Krautkramer USLT2000 device with 1MHz ultrasound wave frequency it was stated that grain refinement reduces the attenuation coefficient by about 20-25%. However, the examined alloys can be still classified as the high-damping ones of attenuation greater than 150 dB/m.
In the aluminium alloy family, Al-Zn materials with non-standard chemical composition containing Mg and Cu are a new group of alloys, mainly owing to their high strength properties. Proper choice of alloying elements, and of the method of molten metal treatment and casting enable further shaping of the properties. One of the modern methods to produce materials with submicron structure is a method of Rapid Solidification. The ribbon cast in a melt spinning device is an intermediate product for further plastic working. Using the technique of Rapid Solidification it is not possible to directly produce a solid structural material of the required shape and length. Therefore, the ribbon of an ultrafine grain or nanometric structure must be subjected to the operations of fragmentation, compaction, consolidation and hot extrusion. In this article the authors focussed their attention on the technological aspect of the above mentioned process and described successive stages of the fabrication of an AlZn9Mg2.5Cu1.8 alloy of ultrafine grain structure designated for further plastic working, which enables making extruded rods or elements shaped by the die forging technology. Studies described in the article were performed under variable parameters determined experimentally in the course of the alloy manufacturing process, including casting by RS and subsequent fragmentation.