Degradation and toxicity changes in aqueous solutions of chloroacetic acids by Fenton-like treatment using zero-valent iron

Three priority pollutants, i.e. mono-, di-, and trichloroacetic acids, were degraded by the conventional Fenton AOP system (Fe²⁺ and H₂O₂). The results obtained suggest that the degradation decreased in the order: monochloroacetic, dichloroacetic, and trichloroacetic acid. The best of advanced oxidation processes (AOPs) for the degradation of trichloroacetic acid was reductive dechlorination with the use of zero-valent iron (Fe°). The results of Escherichia coli toxicity tests revealed that the reagents’ toxicity after the Fenton treatment process was decreased.     

Preparation of polyaniline in the presence of polymeric sulfonic acids mixtures: the role of intermolecular interactions between polyacids

Polyaniline (PANI) was synthesized by chemical oxidation of aniline in the presence of mixtures of water-soluble poly(sulfonic acids) of different nature. Under these conditions, the use of polyacid templates leads to the formation of interpolymer complexes of PANI and polyacid mixtures. The obtained PANI complexes were characterized by UV, visible, near IR, and Fourier transform infrared spectroscopy. It was shown that the rigidity of the polyacid backbone and the composition of a polyacid mixture affect the electronic structure of PANI complexes and the duration of the induction period of aniline oxidation. Domination of the more rigid-backbone template in the synthesis of PANI complexes with mixtures of the rigid- and flexible-backbone polyacids was observed. According to the viscometry and FTIR spectroscopic data, the reason of the domination is the existence of the intermolecular interaction between the polyacids in the mixture. In this case, duration of the induction period of aniline oxidation was between these values for pure polyacids.     

Influence of ethanol on the chain-ordering of carbonised polyaniline

Polyaniline (PANI) was prepared by the oxidation of aniline hydrochloride with ammonium peroxydisulphate in water or in a water-ethanol mixture. In the presence of ethanol, PANI nanotubes and nanorods were observed. Both products were carbonised in a nitrogen atmosphere at 650°C. Initial and carbonised products were characterised by scanning and transmission electron microscopies, thermogravimetric analysis and wide-angle X-ray scattering. Their molecular structure was studied by UV-VIS, infrared, and Raman spectroscopies. Carbonised sample obtained from the PANI salt prepared in the presence of ethanol exhibits Raman spectrum which corresponds to a more ordered carbon-like material than carbonised samples obtained from the PANI base and the PANI salt prepared in pure water. The influence of ethanol present in the reaction mixture on the molecular and supra-molecular structure of PANI and, consequently, on the enhancement of chainordering of carbonised PANI is discussed.     

The preparation of conducting polyaniline�Csilver and poly(p-phenylenediamine)�Csilver nanocomposites in liquid and frozen reaction mixtures

The oxidation of aniline with silver nitrate in 1?mol?L^?1 acetic acid at 20?°C yielded a composite of two conducting components, polyaniline and silver; the acceleration with 1?mol% of p-phenylenediamine is needed for efficient synthesis. The yield and molecular weight increased when aniline was copolymerized with 10?mol% p-phenylenediamine. Such product displayed metallic conductivity below 180?K and semiconductor type above this temperature. As the result, the conductivity was the same at 100 and 300?K. The oxidation of p-phenylenediamine alone with silver nitrate also produced a conducting composite having the conductivity of 1,750?S cm^?1 despite the assumed nonconductivity of poly(p-phenylenediamine). The present study demonstrates that all oxidations proceeded also in frozen reaction mixtures at ?24?°C, i.e., in the solid state. In most cases, molecular weights of polymer component increased, the conductivity of composites with silver improved, to 2,990?S?cm^?1 for poly(p-phenylenediamine)?Csilver, and remained high after deprotonation with 1?mol?L^?1 ammonium hydroxide.     

Stereoselective synthesis of the polar part of mycestericins E and G

5-O-(t-Butyldimethylsilyl)-3-deoxy-3-C-hydroxymethyl-1,2-O-isopropylidene-3-(methoxycarbonylamino)-α-d-xylofuranose IV has been proved to be an appropriate building block in the stereoselective synthesis of methyl (4S)-4-[(1′R)-1′-acetoxy-4′-oxobutyl]-3-benzyl-2-oxooxazolidine-4-carboxylate III representing the polar part of the naturally occurring mycestericins E and mycestericins G.     

Selected In Situ Hybridization Methods: Principles and Application

We are experiencing rapid progress in all types of imaging techniques used in the detection of various numbers and types of mutation. In situ hybridization (ISH) is the primary technique for the discovery of mutation agents, which are presented in a variety of cells. The ability of DNA to complementary bind is one of the main principles in every method used in ISH. From the first use of in situ techniques, scientists paid attention to the improvement of the probe design and detection, to enhance the fluorescent signal intensity and inhibition of cross-hybrid presence. This article discusses the individual types and modifications, and is focused on explaining the principles and limitations of ISH division on different types of probes. The article describes a design of probes for individual types of in situ hybridization (ISH), as well as the gradual combination of several laboratory procedures to achieve the highest possible sensitivity and to prevent undesirable events accompanying hybridization. The article also informs about applications of the methodology, in practice and in research, to detect cell to cell communication and principles of gene silencing, process of oncogenesis, and many other unknown processes taking place in organisms at the DNA/RNA level.     

Canonical-type connection on almost contact manifolds with B-metric

The canonical-type connection on the almost contact manifolds with B-metric is constructed. It is proved that its torsion is invariant with respect to a subgroup of the general conformal transformations of the almost contact B-metric structure. The basic classes of the considered manifolds are characterized in terms of the torsion of the canonical-type connection.     

Detection of Intestinal Ischemia-Reperfusion Injury by Fluorescence Analysis of Intestinal Samples

The aim of this study was to evaluate endogenous fluorescence of small intestine samples and compare them with the histopathological results. The autofluorescence of intestinal homogenates and histopathological injury index after 1h of mesenteric or portal ischemia, and 1 or 24 hours of reperfusion was analysed. Our results revealed two maximum peaks on the EEM. Increase of the intestinal histopathological injury index was accompanied with significant increase of fluorescence intensities in both zones. Close correlation between autofluorescence and histopathological results was found. Autofluorescence can be used was revealed suggesting use of autofluorescence as a new diagnostic method of intestinal injury.     

Chemical profile and biological activities of Peltigera horizontalis (Hudson) Baumg. thallus and apothecia extracts

Abstract

The aim of this study was to determine, for the first time, the chemical composition of Peltigera horizontalis thallus and apothecia extracts (ether, ethyl acetate, dichloromethane and acetone) by HPLC-UV and GC-MS, and evaluate activity of genotoxic, anticholinesterase, antioxidant and antibacterial potential of acetone extracts. Major constituents of thallus extracts were gyrophoric acid, and methyl gyrophorate while dominant component of apothecia extracts was tenuiorin. The predominant volatile compounds in extracts were methyl orsellinate, dodecyl acrylate, orcinol and orcinol monomethyl ether. The thallus acetone extract at concentration of 2.0 µg mL^?1 gave the greatest decrease in the micronuclei frequency (22.4%) of all tested extracts. Apothecia extract showed stronger antioxidant activity as compared to thallus extract. Tested extracts at concentration of 10?mg mL^?1 exhibited inhibitory effect (16.5% for thallus and 12.8% for apothecia) on pooled human serum cholinesterase. P. horizontalis acetone extracts had no activity against the tested five bacteria strains.     

The conversion of polyaniline nanotubes to nitrogen-containing carbon nanotubes and their comparison with multi-walled carbon nanotubes

Polyaniline (PANI) nanotubes were prepared by the oxidation of aniline in solutions of acetic or succinic acid, and subsequently carbonized in a nitrogen atmosphere during thermogravimetric analysis running up to 830 °C. The nanotubular morphology of PANI was preserved after carbonization. The molecular structure of the original PANI and of the carbonized products has been analyzed by FTIR and Raman spectroscopies. Carbonized PANI nanotubes contained about 8 wt.% of nitrogen. The molecular structure, thermal stability, and morphology of carbonized PANI nanotubes were compared with the properties of commercial multi-walled carbon nanotubes.