Adsorption behavior of arsenic relating to different natural solids: soils, stream sediments and peats.

The sorption of anthropogenically derived arsenic to natural solids plays an important role in the mobility and fate of this toxic metalloid in the environment. The adsorption affinity of dissolved As(V) and As(III) to contrasting natural solids was investigated using model solutions of As(V)/As(III) and homogenized samples of soils, stream sediments and peat cores. The adsorption of As(III) and As(V) on investigated sorbents ran mostly according to the Langmuir model, with high correlation factors (>0.

Gold and silver nanoparticles for biomolecule immobilization and enzymatic catalysis.

In this work, a simple method for alcohol synthesis with high enantiomeric purity was proposed. For this, colloidal gold and silver surface modifications with 3-mercaptopropanoic acid and cysteamine were used to generate carboxyl and amine functionalized gold and silver nanoparticles of 15 and 45 nm, respectively. Alcohol dehydrogenase from Thermoanaerobium brockii (TbADH) and its cofactor (NADPH) were physical and covalent (through direct adsorption and using cross-linker) immobilized on nanoparticles' surface.

Early stages of growth of gold layers sputter deposited on glass and silicon substrates.

Extremely thin gold layers were sputter deposited on glass and silicon substrates, and their thickness and morphology were studied by Rutherford backscattering (RBS) and atomic force microscopy (AFM) methods. The deposited layers change from discontinuous to continuous ones for longer deposition times. While the deposition rate on the silicon substrate is constant, nearly independent on the layer thickness, the rate on the glass substrate increases with increasing layer thickness.

Occurrence of Cronobacter spp. in retail foods.

Aims: To study the occurrence of Cronobacter spp. in foods and to investigate the phenotypic properties of the strains isolated.

Methods And Results: A total of 53 strains of Cronobacter spp.

Furanocoumarins in celeriac from different farming systems: a 3-year study.

Background: The aim of this 3-year study was to investigate the effect of different celeriac cultivation strategies on the content of naturally occurring toxicants furanocoumarins, represented by psoralen, bergapten, xanthotoxin and isopimpinellin. The products from organic farming in which anaerobically fermented pig slurry was used were compared against those obtained from other treatment systems: mineral, combined and non-fertilised.

Results: The average levels of furanocoumarins for all 3 years (determined by gas chromatography-mass spectrometry) in varieties Albin and Kompakt were 2.

Modification of chitosan-methylcellulose composite films with meso-tetrakis(4-sulfonatophenyl)porphyrin.

Polysaccharide films containing chitosan, methylcellulose, and a mixture of these polysaccharides in various ratios were prepared and modified with meso-tetrakis(4-sulfonatophenyl)porphyrin in an aqueous medium at pH 7. The modified films were compared with the initial films using spectroscopic methods and microscopic imaging. Electronic (UV-vis absorption, electronic circular dichroism (ECD)) and vibrational (FTIR and Raman) spectra showed that the porphyrin macrocycles had a strong affinity toward chitosan and did not interact with the methylcellulose.

The effect of humic acids on the reverse osmosis treatment of hazardous landfill leachate.

This study deals with the treatment of hazardous waste landfill leachate with the help of reverse osmosis. The landfill is located in an abandoned brown coal pit in northern Bohemia. The leachate contained 7.

The survival of micromycetes and yeasts under the low-temperature plasma generated in electrical discharge.

The fungicidal effect of low-temperature plasma generated by positive direct current discharge and its influence on the growth dynamics was evaluated on three micromycete species and yeast in water suspensions. The fungicidal effect was lower than analogous bactericidal effect and differs substantially among various fungal species. Together with the cidal effects, the slower growth of exposed fungal spores was observed.

Metadynamics modelling of the solvent effect on primary hydroxyl rotamer equilibria in hexopyranosides.

Accurate modelling of rotamer equilibria for the primary hydroxyl groups of monosaccharides continues to be a great challenge of computational glycochemistry. The metadynamics technique was applied to study the conformational free energy surfaces of methyl alpha-D-glucopyranoside and methyl alpha-D-galactopyranoside, employing the GLYCAM06 force field. For both molecules, seven to eight conformational free-energy minima, differing in the omega (O-5-C-5-C-6-O-6) and chi (C-3-C-4-O-4-HO-4) dihedral angles, were identified in vacuum or in a water environment.

Modified aluminosilicates as low-cost sorbents of As(III) from anoxic groundwater.

The utilization of low-grade clay materials as selective sorbents represents one of the most effective possibilities of As removal from contaminated water reservoirs. The simple pre-treatment of these materials with Fe (Al, Mn) salts can significantly improve their sorption affinity to As oxyanions. The natural kaolin calcined at 550 degrees C (mostly metakaolin) and raw bentonite (mostly montmorillonite) pre-treated with Fe(II), Fe(III), Al(III) and Mn(II) salts were used to remove of As from the model anoxic groundwater with As(III) concentration about 0.

ICP-MS determination of heavy metals in submerged cultures of wood-rotting fungi.

Accumulation of five heavy metal ions by five species of wood-rotting basidiomycetes during a 9-day cultivation was studied. Contents of Cd, Cu, Pb, and Zn were measured using ICP-MS; the amount of mercury was determined directly in solid samples using the Advanced Mercury Analyser. A standard operation procedure for the sample preparation and determination of metal content was developed and validated.

Soil flushing by surfactant solution: pilot-scale demonstration of complete technology.

This paper mainly relates to the real polychlorinated biphenyl (PCB)-contaminated soil flushing process, in which an aqueous solution of anionic surfactant was passed through sandy soil having an average concentration 34.3 mg/kg of dry matter. The goal of the treatment was to decrease the PCB concentration in the soil to less than 10 mg/kg, which is a limiting value if the soil is to be used in the field of civil engineering.

Optical sensing of sulfate by polymethinium salt receptors: colorimetric sensor for heparin.

Polymethinium salts based on substituted malondialdehyde have been prepared; the salt with PEG substitution showed high selectivity for sulfate anions and heparin in aqueous medium at physiological condition; intracellular imaging of heparin-rich subcellular compartments was achieved with our polymethinium novel receptor for cancer cell lines.

Nucleotide sequence, organization and characterization of the (halo)aromatic acid catabolic plasmid pA81 from Achromobacter xylosoxidans A8.

The complete 98,192bp nucleotide sequence was determined for plasmid pA81, which is harbored by the haloaromatic acid-degrading bacterium Achromobacter xylosoxidans A8. The majority of the 103 open reading frames identified on pA81 could be categorized as either "backbone" genes, genes encoding (halo)aromatic compound degradation, or heavy metal resistance determinants. The backbone genes controlled conjugative transfer, replication and plasmid stability, and were well conserved with other IncP1-beta plasmids.

Semi-empirical approach to modeling of soil flushing: model development, application to soil polluted by zinc and copper.

This paper describes a semi-empirical approach to modeling the soil flushing technology. A new mathematical model aimed at predicting the course of the continuous soil flushing process by use of the input data obtained from simple batch laboratory experiments is described in the theoretical part. An objective of the study is to apply this new model to soil polluted by zinc and copper (11949 mg kg(-1) and 1895 mg kg(-1), respectively) by flushing the soil with an ammonia nitrogen solution.

Isoflavonoids in non-leguminous taxa: a rarity or a rule?

Isoflavonoids are characteristic metabolites in legumes and an overwhelming number of reports concerning them come from the Leguminosae. Nevertheless, the spectrum of isoflavonoid producing taxa includes the representatives of four classes of multicellular plants, namely the Bryopsida, the Pinopsida, the Magnoliopsida and the Liliopsida. At least 59 non-leguminous families have been reported to produce isoflavones sensu lato; coumestans have been reported in 3 families, coumaronochromones in 3, pterocarpans in 9 and rotenoids in 8 families.

Sorption of As(V) on aluminosilicates treated with Fe(II) nanoparticles.

Adsorption of arsenic on clay surfaces is important for the natural and simulated removal of arsenic species from aqueous environments. In this investigation, three samples of clay minerals (natural metakaoline, natural clinoptilolite-rich tuff, and synthetic zeolite) in both untreated and Fe-treated forms were used for the sorption of arsenate from model aqueous solution. The treatment of minerals consisted of exposing them to concentrated solution of Fe(II).

Interaction of meso-tetrakis(4-sulphonatophenyl)porphine with chitosan in aqueous solutions.

Interaction of meso-tetrakis(4-sulphonatophenyl)porphine (TPPS4) with chitosan (Mr approximately 400 kDa, N-acetyls approximately 20 mol.%) was studied in aqueous solutions. UV-vis absorption and circular dichroism (CD) spectroscopic titration of 10 micromol l-1 TPPS4 with chitosan demonstrated that an addition of the polysaccharide at appropriate concentrations and pH values induce and support self-aggregation of the macrocycles.

Modelling of carbohydrate-aromatic interactions: ab initio energetics and force field performance.

Aromatic amino acid residues are often present in carbohydrate-binding sites of proteins. These binding sites are characterized by a placement of a carbohydrate moiety in a stacking orientation to an aromatic ring. This arrangement is an example of CH/pi interactions.

Distribution of isoflavonoids in non-leguminous taxa - an update.

Common emphasis of the fact that isoflavonoids are characteristic metabolites of leguminous plants sometimes leads to overlooking that the presence of isoflavonoids has been reported in several dozen other families. The spectrum of isoflavonoid producing taxa includes the representatives of four classes of multicellular plants, namely the Bryopsida, the Pinopsida, the Magnoliopsida and the Liliopsida. A review, recently published by Reynaud et al.

Role of CH/pi interactions in substrate binding by Escherichia coli beta-galactosidase.

Interactions between carbohydrates and aromatic amino-acid residues are often observed in structures of carbohydrate-protein complexes. They are characterized by an orientation of the pyranose or furanose ring parallel with the aromatic ring of amino-acid residues. An important role in the formation of these complexes is supposed to be played by CH/pi interactions.

Comparison of yeast (Candida maltosa) and bacterial (Rhodococcus erythropolis) phenol hydroxylase activity and its properties in the phenolic compounds biodegradation.

Aromatic contaminants of the environment, to which belongs phenol and its derivatives, are toxic and in most of the cases hard to degrade. Removal of these pollutants by biological, gentle and effective way, depends on specific environmental conditions in the locality and on the biodegradation potential of the used microbial population. Closer characterization of the biodegradation and enzyme mechanisms is therefore an essential assumption of the successful implementation of microbes.

Biolocalisation and photochemical properties of two novel macrocyclic photosensitisers: a spectroscopic study.

Biolocalisation and photochemical properties of novel macrocyclic photosensitisers, guanidiniocarbonyl-substituted tetraphenylporphyrin (1) and sugar-substituted sapphyrin (2) were investigated by spectroscopic methods. Both photosensitisers absorb in far visible region and showed good tumour localisation. Photosensitiser 2 demonstrated significantly larger absolute and relative to normal tissue (T/N) amount in tumour (330 microg g(-1) wet tissue, T/N=19.

Three-dimensional structure of a monomeric form of a retroviral protease.

The assembly of Mason-Pfizer monkey virus Gag polyproteins into immature capsids and their cleavage by the encoded protease are temporally and spatially separated processes, making the virus a particularly useful model for investigation of protease activation. Here we present a high resolution NMR structure of a fully folded monomer of a 12 kDa M-PMV protease (wt 12 PR) and of a Cys7Ala/Asp26Asn/Cys106Ala mutant (12 PR(D26N/C7A/C106A)). The overall structures of both wt 12 PR and 12 PR(D26N/C7A/C106A) follow the conservative structural motif of other retroviral proteases.

Chaotic patterns in a coupled oscillator-excitator biochemical cell system.

In this paper we examine dynamical modes resulting from diffusion-like interaction of two model biochemical cells. Kinetics in each of the cells is given by the ICC model of calcium ions in the cytosol. Constraints for one of the cells are set so that it is excitable.