Classical chemical sciences
The pure YBCO (YBa2Cu3O7) and optimally praseodymium containing superconductors with general formula; Y1-xPrxBa2Cu3Oz,where x = 0.15 mole respectively, were synthesized by solution route and characterized by XRD, SEM and Raman spectra. X-ray analyses indicated that both of pure and Pr-doped-123-YBCO has orthorhombic superconducting phase. Visualization investigations were made depending upon crystallographic data of pure and Pr-doped 123-YBCO. Both crystals are formed via DIAMOND IMPACT CRYSTAL visualizer. Comparison of structural parameters such as bond length, angles and torsion on angles of pure and Pr-doped 123-YBCO was performed to find out why this ratio of doping ( x ~ 0.15 mole ) in most cases is reported to be optimum one in literatures.
Keywords: Superconductor; Solution Synthesis; Visualization; X-ray; Scanning Electron Microscopy; Praseodymium-doped YBCO
Amino acids have the ability to control corrosion of various metals such as carbon steel, zinc, tin and copper. It behaves as an inhibitor in acid medium, neutral medium and in desecrated carbonate solution. Various techniques like weight loss method, polarization study and AC impedance spectra have been used to evaluate the corrosion inhibition efficiency of amino acids. The protective film has been analyzed by IR spectroscopy, atomic force microscopy, scanning electron microscopy and auger electron spectroscopy. Adsorption of amino acid on metal surface obeys Langmuir, Flory-Huggins or Temkin isotherm, depending on nature of metal and corrosive environment. Polarization study reveals that amino acids can function as anodic or cathodic or mixed type of inhibitor depending on nature of metal and corrosive environment.
Keywords: corrosion inhibition, amino acids, polarization, metals and alloys.
Materials and environmental chemistry
Urban airborne particulate matters and dusts can be both ingested and inhaled, causing health damage due to their size, shape and nature of toxic components. Our aim was to characterize the concentration, enrichment and host phases of lead and zinc in total suspended particulate matter (TSP) and settled dust (SD) samples from Budapest, Hungary. TSP samples were collected from the air filters placed in the respiration channels of thermal power stations, while SD samples were collected in glass pots next to a busy street. Detailed mineralogical, chemical and magnetic susceptibility analyses were carried out on these samples. The concentrations of both elements were generally higher in the TSP (330-3597 mg kg-1 for Pb and 1342-19 046 mg kg-1 for Zn) than in the SD samples (58-474 mg kg-1 for Pb and 399-1140 mg kg-1 for Zn). Additionally, they showed moderate contamination in the SD samples, while moderate to heavy contamination in TSP samples with enrichment factors up to 4.9 for Pb and 5.3 for Zn. Transmission electron microscopy (TEM) analyses showed that magnetite may contain significant amount of Zn (up to 2.60 wt%) and Pb (2.50 wt%). However, Zn could be also associated with layer silicates (up to 5.06% by wt) and Ca-carbonates. Moreover, Zn also appeared as major phase constituent in carbonates and oxides. Magnetite particles are resistant to weathering releasing its toxic components slowly to the environment, while layer silicates (and carbonates, Zn-oxides) may be the potential source of mobile toxic metals in the studied materials.
Keywords: air pollution, heavy metals, magnetite, clay minerals, urban geochemistry
In order to produce good quality products it is necessary to find out about the quality of pastures to be grazed. It is also important to know the element composition of grazed herbs and the demands of animals bred on pastures, especially where the environment may influence the feed safety conditions of plants – as in the case of floodplains. Our objective was to determine that what the element composition (Cu, Zn, Mn and Fe contents) of herbs grown on a floodplain which was subsided by a heavy metal contaminated sediment. Our results call an attention to the differences in the accumulation of herbs. Bidens tripartitus, Lotus corniculatus and Vicia cracca grown in the floodplain showed the higher amounts of Fe and Zn, but the effect of heavy metal contamination on the element contents of other examined plants cannot be proved.
Keywords: microelement content, pasture, herb
Beside anthropogenic sources, trace metals can be found in the parent material from which the soils develop. Whether these inputs will become toxic and to what extent mobility depends upon a number of factors: specific chemical and physical trace metal characteristics, soil type, land use, geomorphological characteristics within the soil type and exposure to emission sources. Processes that control the mobility, transformation and toxicity of metals in soil are of special importance in the soil root developing zone – the rhizosphere. For this reason, there is a considerable interest in understanding trace metals behaviour in soil, with special emphasis on the way they enter the soil and on processes by which plants take them up. Full understanding and prediction of chemical behaviour of an element in the environment is possible only by identification of all forms in which that element can be found under different environmental conditions. Various chemical methods, geochemical models and biotests are used for assessment of the bioavailable metal fraction in soil. However, these methods are not universally applicable for all elements and different soil characteristics. Chemical methods for assessment of metal bioavailability are commonly grouped within methods for identification of total metal content in soil, methods for assessment of currently available and potentially available fractions, methods for prediction of metal speciation in soil solution. This article offers a critical review of methodologies available for assessing metal speciation in solid and liquid phases in soils taking into consideration the array of parameters that might influence uptake and effects upon the plant.
Keywords: Soil contamination, Metal speciation, Chemical extraction; Fractionation, Potential mobility.
According to statistical data the amount of sewage sludge does not increase as it was prognosed some years ago. Although this is a positive effect, we have to solve the problem of recycling of the sewage sludge. The appropriate chemical composition of municipal sewage sludge compost is suitable for nutrient supply in the agriculture. The small-plot experiment with sewage sludge compost was started in the spring of 2003. Three doses of compost (9, 18, 27 t ha-1) and a control treatment were used in the experiment. The small-plot experiment was retreated in the fall of 2006 and 2009. In the composting process bentonite, rhyolite and wheat straw were used as additives for improving the quality of the compost. Our purpose was to stabilize or increase the fertility of sandy soil and contribute to the reduction of environmental pollution. In the plot experiment there were three test plants: triticale, maize and pea. These three plants were sawn in crop rotation. We examined the concentration of nickel (Ni) and zinc (Zn) in two soil layers, 0-30 and 30-60 cm in 2008-2009 years. We could not observe toxic effects on the test plants. The aim of the experiment was to investigate whether the application of sewage sludge compost cause hazardous accumulation of toxic elements in the soil and plants.
Keywords: sewage sludge compost, agriculture, toxic element, sandy soil
Biochemistry, molecular biology and biotechnology
Cadmium (Cd) is a heavy metal and a major environmental pollutant. The general population is exposed to Cd mainly via drinking water and food products. We have developed a mouse experimental model to investigate the in vivo effects of Cd and the chelating agent monensin on testis and sperm count during adulthood. Animals were divided into three groups: normal control (receiving distilled water and food): Cd group, exposed to 20 mg kg-1 b.w. Cd(II) acetate for the first 2 weeks of the experimental period and Cd+monensin group, receiving monensin (18 mg kg-1) after Cd-intoxication (from 15th to 28th day). Histological observations of the testis demonstrated that Cd induced desquamation of germ cell and their assembly in the luminal region of the tubules. Areas in the testis without spermatides in latest steps of differentiation were also observed in this group. Monensin administration to Cd-treated animals restored histology of the testis to normal to a great extent (despite some Sertoli-cell-only tubules). Statistically significant changes in sperm count were not established for any of the experimental groups. Monensin can reduce injury of the testis and normalize its morphology after subacute exposure to Cd. The results of the present study demonstrated that monensin is a good compound in chelating therapy of some heavy metal intoxications.
Keywords: cadmium intoxication, monensin, in vivo model, testis morphology
It is well-known that essential heavy metals like copper (Cu), mainly at higher concentrations usually cause overproduction of reactive oxygen species (ROS) resulting in oxidative stress in plants. Till date many experiments were carried out to evaluate how Cu toxicity influences in adult plants but only a few reports are available about the effects during germination. Since this is a very sensitive period and the effects of heavy metal stress are more serious. The aims of our study were to investigate potential oxidative stress and antioxidative defense mechanisms beside potential morphological and/or anatomical alterations in germinating seeds of Indian mustard (Brassica juncea L.) exposed to excess Cu. The following parameters were evaluated to describe oxidative stress: FRAP (ferric reducing ability of plasma), lipid peroxidation (LP), reduced glutathione content (GSH), total protein content and the activity of glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPOX) and glutathione reductase (GR). We also made an assessement of histochemically LP and the loss of plasma membrane integrity in the root tips, the production of callose and the lignification of cell walls. Our results showed that Cu treatments were followed by notable GSH-depletion. We could detect LP histochemically in the root tips. The application of Cu increased the activity of SOD in time and dose-dependent manner. The activity of CAT and GPOX increased after 48-96h Cu excess. Morphological symptoms of metal toxicity occurred such as stunted, hooked-formed and brownish root tips. Production of callose and lignification of cell walls could be visualized, too.
Keywords: copper stress, Brassica juncea L., germination, oxidative stress, callose, lignin.
Forty-four acacia honey samples from beekeepers and hypermarkets were collected examined in our laboratory. Five elements (Al, Cu, Fe, Li, Sr, Zn) were analysed by ICP-OES and seven elements (As, Ba, Cd, Cr, Ni) were also determined by ICP-MS. Aluminium, iron and zinc were the most abundant elements found in our samples under study. The concentration was ranging between 100.0 and 4910 μg kg-1 for Fe, 319.0 and 4440 μg kg-1 for Zn and 242.0 and 3095 μg kg-1 for Al. The lowest values were 4.648±4.184 μg kg-1 for Cd, 27.12±13.62 μg kg-1 for Cr and 42.49±20.37 μg kg-1 for As. The element concentration increased in the following order: Cd < Cr < As < Li < Ni < Ba < Cu < Sr < Al < Zn < Fe.
Keywords: Honey, Trace element content, ICP-MS, ICP-OES
Industrial and engineering chemistry
Catalytic properties of FV series and RFW-3 wax hydrofining catalysts have been introduced and compared. Effects of different catalysts such as FV-10, FV-30, RJW-2 and RJW-3 on the quality of wax at a pilot plant have been also discussed. FV-30’s life has been also tested at a large-scale plant. The experimental results show that RJW-3 have high catalytic performance and wax products obtained meet the requirement of Chinese wax standard.
Keywords: China; wax; overview; hydrofining; catalysts