Volume 3, Issue 1

This study deals with the application of several multivariate statistical methods (cluster analysis, principal components analysis, multiple regression on absolute principal components scores) for assessment of soil pollution by heavy metals. The sampling was performed in a heavily polluted region and the chemometric analysis revealed four latent factors, which describe 84.5 % of the total variance of the system, responsible for the data structure. These factors, whose identity was proved also by cluster analysis, were conditionally named “ore specific”, “metal industrial”, “cement industrial”, and “steel production” factors. Further, the contribution of each identified factor to the total pollution of the soil by each metal pollutant in consideration was determined.

The possibility to prepare hybrids made by poly(vinyl acetate) (PVAc), poly(methyl methacrylate) (PMMA) and/or poly(ethyl acrylate) (PEtA) with TiO2 was studied. The processes of polymer formation-radical polymerization and sol-gel process for inorganic network —were achieved simultaneously. Due to a high reactivity of titanium isopropoxide (TIP) in the sol-gel process, a complexant comonomer, allyl acetoacetate (AlAcAc), was used. Covalent bonds between polymer and inorganic chains were obtained by addition of trialkoxysilane derivates with vinyl (VTES) or methacryloyl (MPTS) groups. The presence of TIP inhibits the radical polymerization of vinyl acetate (VAc). The PVAc-TiO2 hybrids were produced by the sol-gel process of TIP in the presence of pre-obtained PVAc. Except for VTES and MPTS, trialkoxysilane derivates with methyl (MeTES), octyl (OTES) and phenyl (PTES) groups were used. The thermal stability of hybrids is strongly affected by TiO2 presence and by the type of trialkoxysilane derivates. The thermal stability of PVAc hybrids decreases in the presence of TiO2 inorganic network. The glass transition temperature of polymers increases in the presence of the inorganic network.

The PdCl2/Fe/I2/Py catalytic system (Py-pyridine), reported to be highly active in the reaction of nitrobenzene carbonylation to ethyl phenylcarbamate was studied. The present paper describes the role of catalyst components and its effect on the activity and selectivity of the catalyst. The increase in the amount of PdCl2 in the system while retaining a constant level of the other catalyst components, results in the increase of both carbamate and aniline yields. The increase in the amount of iron while retaining the other components constant, initially causes an increase in the carbamate yield; however, at Fe: Pd ratios higher than 36, the carbamate yield remains constant. The change in the amount of iron has no effect on the amount of aniline formed in the system. An increase in the amount of iodine in the system while retaining the other components constant, results in a decrease in carbamate yield and a considerable increase in the aniline yield of the reaction products.

The mechanistic rationalisation of specific ‘microwave effects’ previously reported in a range of chemical reactions suggests that they may be observable in the freeradical copolymerisation of comonomer pairs capable of forming donor-acceptor complexes. Polymerisation under microwave irradiation is carried out for several comonomer pairs with weak donor-acceptor interactions, and no acceleration in rate or change in degree of alternation attributable to changes in propagation are observed. An increase in reaction rate of 150–200 % is observed for all systems, with trends in molecular weight suggesting this was due to an increase in radical flux. This is consistent with earlier reports of rate enhancement for free-radical polymerisations using the initiator 2,2′-azobis-isobutyronitrile, and it is proposed that microwave irradiation may reduce the amount of geminate radical recombination.

The main objective of this paper is to study the thermal stability of some aromatic copolyethers containing a propylenic spacer. Some of the investigated copolyethers displayed a liquid crystalline (LC) behavior, with the presence of the mesogenic groups in the main chain, inducing high values of the thermal transition temperatures. As a consequence, a thermal stability study was necessary to establish the maximum temperature value for the LC behavior characterization. A thermal degradation mechanism is proposed, taking into consideration the azobenzenic unit as the weakest link in the polymer chain and thus, the starting point of the thermal degradation process. The degradation mechanisms were correlated with the chemical structure and the polarity and conformation of the chains. Conformational analysis was performed using molecular simulations. Freeman-Caroll and Coats-Redfern methods were used to calculate some kinetic characteristics.

(R, R)-(−)-N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminocobalt(II) was encapsulated into MCM-22 using the zeolite synthesis method. The encapsulated catalyst proved to be active in the oxidation of α-methylstyrene with NaOCl with higher specific activity than the homogeneous catalyst. At the same time, this encapsulated catalyst was completely inactive in the hydrolytic kinetic resolution of racemic styrene oxide. This observation is in a good correlation with the assumption of the cooperative bimetallic mechanism proposed by Annis and Jacobsen.

The inclusion of vanadocene dichloride (VDC) and 1,1′-dimethyl vanadocene dichloride (MeVDC) into cyclodextrines (α-CD, β-CD and γ-CD) was studied by EPR spectroscopy. It was found that VDC and MeVDC with β-CD and γ-CD form true inclusion compounds, but with α-CD, VDC and MeVDC gave only fine dispersion mixtures. The inclusion was validated by anisotropic EPR spectra of solid samples. In addition, the antimicrobial was validated by anisotropic EPR spectra of solid samples. In addition, the antimicrobial behavior (against E. coli) of each of the complexes was determined. It was established that not only did VDC and MeVDC cause elongation of E. coli, but also the new vanadocene inclusion complexes were effective in this regard.

This paper presents the results of a study on the optimization of the determination of total arsenic and its species using the absorption atomic spectrometry method combined with hydride generation and in-situ concentration on the inner walls of the graphite tube. To ensure a maximum efficiency of the in-situ analyte concentration on the graphite tube walls, a palladium modifier subjected to preliminary thermal reduction was used. The limits of detection (3σ) were 0.019 ng/mL for total As and 0.031 ng/mL for As(III) at the preliminary analyte concentration for 60s. The optimised procedure of the analyte concentration on the inner walls of the atomiser (graphite tube) was applied for determinations of arsenic in samples of ground water. The content of arsenic in the samples studied varied from 0.21 ng/mL to 0.80 ng/mL for As(III), and from 0.19 ng/mL to 1.24 ng/mL for As(V).

β-galactosidase from Penicillium canescens was immobilized on chitosan, sepharose-4B, foamable polyurethane and some other carriers. The highest yield of immobilization (up to 98%) was obtained by using chitosan as a carrier. The optimum pH and temperature were not significantly altered by immobilization. High stability of immobilized β-galactosidase during storage was demonstrated. Efficient lactose saccharification (over 90%) in whey was achieved by using immobilized β-galactosidase.

The increase of activities of fission products and transmutation products in the primary coolant of a nuclear power plant indicates the presence of fuel rod failures. The measurement of the activity concentration of the primary coolant was able to detect fuel failures in the reactor core. Microanalytical methods for examining individual hot particles have been developed and applied to fuel failure detection under normal operation conditions as well as during the severe fuel damage that occurred in the cleaning tank incident at Unit 2 of NPP Paks in April 2003. Several faulty fuel rods can be detected simultaneously by the characterization of individual hot particles originating from the primary water. The analysis of particles originating from the damaged fuels provides information relating to the dissolution process of the fuel debris.

Transformation of β-carboline derivatives into optically active entities were studied and the de and ee values of the resulted compounds were detected.

Some oxyhalides can be found in drinking waters as inorganic disinfection byproducts. An on-line coupled capillary isotachophoresis—capillary zone electrophoresis (CITP-CZE) method was developed for the analysis of chlorate, chlorite and bromate in water. The optimized CITP-CZE electrolyte system consisted of the following: 10 mM—HCl+20 mM—β-Alanine (leading electrolyte), 5 mM—succinic acid (terminating electrolyte), and 10 mM—succinic acid +5 mM—β-Alanine +0.1% HPMC (carrier electrolyte). A clear separation of oxyhalides from other components of drinking water was achieved within 25 min. Method characteristics, i.e., linearity (0–200 ng/mL), accuracy (88–110%), intra-assay (3–5%), quantification limit (5–15 ng/mL), and detection limit (2–5 ng/mL), were determined. Minimum labor requirements, sufficient sensitivity and low running cost are important attributes of this method. It was found that the developed method is useful for the routine analysis of oxyhalides in water.

The enamine (HEAID) obtained from aniline and 2-acetyl-1,3-indandione (2AID) behaves as a bidentate ligand in coordination with copper (II) ion. Two types of crystals, apparently different in shape, were isolated and studied by single-crystal X-ray diffraction. The X-ray data for the brown rhombic crystals of compound 1 shows a mononuclear complex of Cu(II) coordinated with two EAID-anions, Cu(EAID)2. The X-ray data for the green crystals of compound 2 shows a dinuclear Cu(II) complex with two OH− groups acting as bridging ligands, [Cu2(μ-OH)2(EAID)2]. In both cases the ligand coordinates after deprotonation of the amine group.

The 1,1’-dimethylvanadocene dichloride ((C5H4CH3)2VCl2) reacts in aqueous solution with various carboxylic acids giving two different types of complexes. The 1,1’-dimethylvanadocene complexes of monocarboxylic acids (C5H4CH3)2V(OOCR)2 (R=H,CCl3, CF3, C6H5) contain two monodentate carboxylic ligands, whereas oxalic and malonic acids act as chelate compounds of the formula (C5H4CH3)2V(OOC-A-COO) (A=−, CH2). The structure of the (C5H4CH3)2 V(OOCCF3)2 complex was determined by single crystal X-ray diffraction analysis. The isotropic and anisotropic EPR spectra of all the complexes prepared were recorded. The obtained EPR parameter values were found to be in agreement with proposed structures.

This paper describes the crystal structure of a novel, hypothetical 3-,8-connected cubic structural pattern with the binary stoichiometry A3B8. The novel pattern lies in space group Pm3m, number 221. It possesses the Wells point symbol (4468812)3(43)8 and has the Wellsean Schläfli index (6, 4.3636). It is derived from the Andreini space filling arrangement of octahedra and cuboctahedra by replacing the areas where there are face-sharing of the polyhedra with the inscription of 3-connected, trigonal planar vertices, and retaining the points where the polyhedra share vertices in cube coordination. The structure-type could be representative of a binary metal oxide in which the metal cation attains a relatively high oxidation state of 51/3+. Possible metal oxide models for the structure-type include M3O8 (where M is a Group 6 or 7 elements).

The geometry and electronic structure of several phosphinine-ether macrocycles were investigated at semiempirical level. The calculated geometries are in good agreement with experimental data. Compared to phosphinine, the coordinative abilities of phosphinineether macrocycles based on energy considerations suggest a little lowered π acceptor character, while π donor character is improved. The molecular environment causes a significant mixing of phosphinine and phenyl substituent π levels. The geometry and electronic properties of phosphinine-ether macrocycles can provide significant host coordination properties for guest species.

The question addressed in this paper is the flattening of the valley separating two growth hillocks emanating from screw dislocations during crystal growth. It is argued that both thermodynamic and kinetic effects contribute to this result, at least on a quasi-atomic scale. If performed under low enough supersaturation the growth leads to the formation of the face morphology corresponding to the minimum of the surface free energy. Accelerated step annihilation in the valley floor is a universal factor, which favors face flatting under any supersaturation.

The unit cell edge length, a, of a set of complex cubic perovskites having the general formula A22+BB′O6 is predicted using two methodologies: multiple linear regression and artificial neural neworks. The unit cell edge length is expressed as a function of six independent variables: the effective ionic radii of the constituents (A, B and B′), the electronegativities of B and B′, and the oxidation state of B. In this analysis, 147 perovskites of the A22+BB′O6 type, having the cubic structure and belonging to the Fm3m space group, are included. They are divided in two sets; 98 compounds are used in the calibration set and 49 are used in the test set. Both models give consistent results and could be successfully use to predict the lattice cell parameter of new members of this series.