In the present work the Ni and Cd extraction from the electrode material of spent Ni-Cd batteries by bioleaching using the bacteria Acidithiobacillus ferrooxidans was examined. The possibility of the use of the bacteria for both the Ni and Cd recovery was analyzed. The anode of Ni-Cd batteries contains Ni0, Ni(OH)2, Cd0 and Cd(OH)2. The cathode is covered by nickel hydroxides and nickel oxy-hydroxides. The pH values and content of Ni and Cd in the solution were monitored throughout the experiment (the initial pH was 1.5, the experiment took 28 days). The bioleaching efficiency of Ni and Cd from anode powder reached 5.5% and 98%, respectively. During the cathode powder bioleaching Ni and Cd efficiency reached 45% and 100%, respectively. Throughout the bioleaching process mainly the dissolution of hydroxides occurred meanwhile Ni0 leaching was not observed. The AAS analysis was used to analyze the amount of Ni and Cd in the solutions. The amount of Ni and Cd present in the solid samples before and after bioleaching was examined using X-ray analysis.
The submitted paper deals with the study of combination of chemical and biological-chemical methods for the heavy metals elimination from the acid mine drainage. The experiments were carried out at the laboratory scale using a synthetic solution with similar properties to the real sample of acid mine drainage, originating from the zinc mine located in Tùnel Kingsmill outflow of the Rio Yaulì (district of Yauli - Perù). The successive repetition of the metal precipitations as hydroxides (chemical method) and sulphides (biological-chemical method) at the various acid mine drainage pH was the basis of the examined processes. For the hydrogen sulphide production the sulphate-reducing bacteria of genus Desulfovibrio were used. Results confirmed the precipitation of Fe, As, Al and Mn in the hydroxide form; Cu and Zn in the form of sulphides. For the selective removal of Cu, Zn, Al and Mn the excellent results were received. Selective precipitation of Fe and As was not so successful since the co-precipitation of Fe and As was later determined as a main mechanism of the precipitate forming.
This study presents the results of the testing toxicity of the contaminated sediments from the water reservoir of Ružín No.I deposit (Slovak Republic) by using Phytotoxkit tests (MicroBioTests Inc., Belgium). The Phytotoxkit system is a screening tool used for a variety of toxicity testing applications. The advantages of this toxicity bioassay are its speed, relative simplicity and low cost compared to chemical analysis and many other biotests. Evaluation of sediments phytotoxicity was based on the testing of seed germination and the assesment of the root growth decrease of the plant Sinapis alba which allows to complete the assays after only 3 days of incubacion. Chemical analysis of the sediment samples involved determination of heavy metal (Cu, Zn, Ni, As, Sb and Hg) concentration. No potential phytotoxic effect of heavy metals in contaminated sediments was observed in the majority of tested seeds of Sinapis alba.
Antioxidant Activity of Milling Fractions of Selected Cereals
The aim of this study was to evaluate antioxidant potential of four milling fractions of selected cereals grew in the year 2009 and 2010. Free radical scavenging activity of samples was measured using DPPH assay and reducing power was determined using FRAP assay. Secondary, total phenolic and flavonoid content of cereal extracts was evaluated. We found that flour fractions (break flour and reduction flour) showed the lower proportion of the total antioxidant potential than bran fractions (fine bran and coarse bran), which was balanced in observed years. Extract from barley had the highest values of antioxidant activity and polyphenol content.
Bioinformatic Analysis of Prophage Endolysins and Endolysin-Like Genes from the Order Lactobacillales
Endolysins belonging to the group of peptigoglycan hydrolases, which are able to cleave peptidoglycan in bacterial cell walls, become an extensively studied group of enzymes. Thanks to their narrow target specificity and low probability of resistance they are considered to be an appropriate alternative to conventional antibiotics. The present paper concerns the occurrence of endolysin and endolysin-like genes in genomes of bacteria belonging to the order Lactobacillales. Using bioinformatic programmes we compared and analysed protein sequences of catalytic and cell wall binding (CWB) domains of these enzymes, their preferred combinations, their phylogenetic relationship and potential occurence of natural "domain shuffling". The existence of this phenomenon in selected group of enzymes was confirmed only in limited range, so we assume that the natural trend is the distribution of "well-tried" combinations of catalytic and CWB domains of endolysin genes as a whole.
This minireview summarizes the basic ways of application of chemometrics in medicine and pharmacy. It brings a collection of applications of chemometric used for the solution of diverse practical problems, e.g. exploitation of biologically active species, effective use of biomarkers, advancement of clinical diagnosis, monitoring of the patient's state and prediction of its perspectives, drug design or classification of toxic chemical substances. The aim of this contribution is a brief presentation of versatile potentialities of contemporary chemometrical techniques and relevant software. They are exemplified by typical cases from literature as well as by own research results of the Chemometrics group at Department of Chemistry, the University of Ss. Cyril & Methodius in Trnava.
Monitoring of Polycyclic Aromatic Hydrocarbons (Pahs) in Surface Water of the Hungarian Upper Section of the Danube River
The aim of this paper is to investigate the concentrations of polycyclic aromatic hydrocarbons (PAHs) in surface water of the Hungarian upper section of the Danube River in the period of 2007-2010. A total of 77 water samples were collected from the sampling sites located at Rajka, Medve and Komárom (1848, 1806 and 1766 river km) under the authority of the Inspectorate for Environment, Nature and Water of the North Transdanubian Region designated by the Hungarian National Monitoring Programme. Sixteen PAHs identified by the US Environmental Protection Agency (USEPA) as priority pollutants were monitored.
Concentrations of total 16 PAHs (ΣPAHs) ranged from 25 to 357 ng·L-1 with the mean value of 98.27 ± 58.48 ng·L-1. The low and medium molecular weight PAHs (2-3 and 4 ring) ranged from below method detection limit (<1) to 136 ng·L-1 while high molecular weight PAHs (5-6 ring) were present at much lower concentrations (<1-25 ng·L-1). The 2-3-ring PAHs contributed to about 64% while 4-6-ring PAHs accounted for 36% of the ΣPAHs. The dominant species are naphthalene and phenanthrene in the surface water. Concentration ratios of specific PAH compounds including anthracene/(anthracene+phenanthrene) and fluoranthene/(fluoranthene+pyrene) were calculated to evaluate the possible sources of PAH contamination. The levels of ΣPAHs determined in our study were compared with other sections of the Danube and other regions of the world.
Optimization of Barley Mature Embryo Regeneration and Comparison with Immature Embryos of Local Cultivars
Regeneration ability of plant cells or tissues in explant culture is one of the key factors affecting success of genetic transformation. In experiments, the effect of explant type (whole embryo, scutellum embryonic axis, meristematic/central zone of embryonic axis) and plant growth regulators (BAP or TDZ) on mature embryo regeneration was determined. Explant type significantly affected regeneration efficiency. While no regenerants were observed using mature scutella, whole embryos or embryonic axes produced the highest number of regenerants. Using embryonic axes with discarded apical and basal parts, regeneration efficiency dramatically decreased. No statistical differences in regeneration were observed between BAP and TDZ added to the regeneration medium in concentration 0.1 or 1 mg l-1. At last, regeneration ability of mature embryos of nine Slovak spring barley cultivars (Donaris, Ezer, Levan, Ludan, Nitran, Pribina Sladar, Orbit, Pax) and Golden Promise as a model cultivar was examined and compared with regeneration ability of immature embryos which have been usually used for genetic transformation of barley. Although the regeneration from mature embryos was very weak, the same cultivars Golden Promise, Pribina and Levan showed the best regeneration ability by using both, immature and mature embryos. On the other hand cultivars Ezer and Pax belonged to the weakest ones in both experiments.
Quantitative Structure-Antioxidant Activity Relationship of Quercetin and its New Synthetised Derivatives
Interest in the biological activity of the flavonoids increases due to the potential health benefits of these polyphenolic components of foodstuff. Our research investigates biological properties of the flavonoids and their new synthetized derivatives, focuses on the relationship between their antioxidant activity and their chemical structures.
Quantitative structure-activity relationship (QSAR) attempts to correlate chemical structure with biological activity using statistical approaches. It is the process by which chemical structure of a molecule is quantitatively correlated with a well defined process, such as biological activity, that can be expressed quantitatively as the concentration of a substance required to give a certain biological response. When physicochemical properties or structures are expressed by numbers, the mathematical relation can be formed between the two. The mathematical expression can then be used to predict the biological response of other chemical compounds.
QSARs represent predictive models derived from application of statistical tools correlating antioxidant activity (including desirable therapeutic effect and undesirable side effects) of chemicals with descriptors representative of molecular structure and properties. Obtaining a good QSAR model depends on many factors, such as the quality of biological data, the choice of descriptors and statistical methods. Any QSAR modeling should ultimately lead to statistically robust models capable of making accurate and reliable predictions of biological activities of new untested compounds.