Effect of selenium oxidation state on cadmium translocation in chamomile plants

Syntheses and spectral characteristics of cadmium(II) compounds (CdSeO₄, CdSeO₃, and Cd(NCSe)₂(nia)₂) containing selenium in oxidation states (VI), (IV), and (-II) are described. In Cd(NCSe)₂(nia)₂, nicotinamide (nia) and selenocyanate anions are bonded to Cd atom as N-donor monodentate ligands. Nicotinamide is coordinated through the ring nitrogen atom. The effects of these selenium compounds as well as Cd(NCS)₂(nia)₂ on the growth and Cd accumulation in roots and shoots of hydroponically cultivated chamomile plants (cultivar Lutea) were studied. In the applied concentration range (12–60 μmol dm⁻³) Cd(NCS)₂(nia)₂ affected neither the length nor the dry mass of roots and shoots. Other compounds applied at 24 μmol dm⁻³ and 60 μmol dm⁻³ significantly reduced dry mass of roots and shoots. Selenium oxidation state in the cadmium compounds affected Cd accumulation in plant organs as well as Cd translocation within the plants, which was reflected in the values of bioaccumulation (BAF) and translocation factors (S/R). Cd amount accumulated by shoots was lower than that in the roots. The highest BAF values determined for Cd accumulation in shoots were obtained with CdSeO₄. Substitution of S with Se in the Cd(NCX)₂(nia)₂ (X = Se or S) caused an increase of Cd translocation into the shoots. Presented at the XVIIIth Slovak Spectroscopic Conference, Spišská Nová Ves, 15–18 October 2006.     

PAMAM Dendrimers as Anchors for the Preparation of Electrocatalytically Active Ultrathin Metallic Films

This paper describes the formation of catalytically active thin films of Pt, Pt/Au, and Pt/Ru on gold substrates stabilized by amine‐terminated polyamidoamine (PAMAM) dendrimers. A monolayer of dendrimer is initially self‐assembled on the gold substrate, which serves as a template for the growth of catalytically active thin films. As dendrimers contain tens to hundreds of functional groups at the periphery, the aggregate strength of the multidentate interactions with the gold substrate leads to the formation of robust films. The films were found to exhibit high catalytic activity for the oxidation of small hydrocarbons such as methanol. Such films offer versatility and scope for the design of effective electrocatalysts, especially in the context of microfuel cells and “dendrichips”; hence, they could find applications in the fields of sensors, fuel cells, and waste‐water treatment.     

Determination of imazalil by on-line coupled capillary isotachophoresis with capillary zone electrophoresis

A simple, rapid and reproducible capillary isotachophoretic on-line coupled with capillary zone electrophoresis (CITP-CZE) method for the determination of IMz in food packaging extracts and its residues in apples is described. A good separation of the IMZ from other sample constituents was achieved within 15 minutes without any sample clean up. Method characteristics (linearity, accuracy, intra-assay and detection limit) were determined. Less amount of time involved, sufficient sensitivity and low running cost are the important attributes of CITP-CZE method.     

Synthesis and binding studies of new bis-calix[4]arenes containing aromatic and heteroaromatic units

A series of new bis-calix[4]arenes containing different aromatic and heteroaromatic moieties have been synthesized. The complexing behavior of these bis-calix[4]arenes have been studied towards different metal ions and it has been found that these bis-calix[4]arenes bind silver ions selectively over other metal ions. The complexation has been studied by liquid-liquid extraction and by NMR and IR spectroscopy.     

Hydrogenation of ethyl esters of 4-phenyl-and (2-furyl)-substituted 2,4-dioxobutyric acids at palladium black

The hydrogenation of ethyl 4-R-2,4-dioxobutyrates (R = phenyl, 2-furyl) at 5% Pt/Al₂O₃ catalyst, modified with cinchonidine, and at palladium black was investigated. The former had low activity under the conditions we tested. The main products during the hydrogenation of these compounds at palladium black are ethyl 4-R-2-hydroxy-4-oxobutyrates. The yield of the phenyl derivative amounts to 68.5%, while the yield of the corresponding 2-furyl derivative amounts to 97%. In the last case ethyl 2-hydroxy-4-oxo-4-(2-tetrahydrofuryl)butyrate was detected as impurity. The optimum conditions for the formation of ethyl 2-hydroxy-4-phenylbutyrate (yield 88.2%) were determined. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 655–659, May, 2006.     

Chromatographic Analysis of Trans Resveratrol in Italian Wines: Comparisons between FL, UV and MS Detection

Resveratrol (3,5,4′-trihydroxystilbene) is a phytoalexin that belongs to the group of stilbenes, known to occur in grapes and consequently in grape products. Its presence in wine is an important qualitative parameter because of the several beneficial effects on human health. The aim of this work is the development of a high-performance liquid chromatographic (HPLC) method for the determination of trans resveratrol in wines, and comparisons between the results obtained by different detection techniques: UV-vis spectroscopy, fluorescence spectroscopy and mass spectrometry. Resveratrol is analysed on a C-18 column using gradient elution. The method permits direct injection of sample, revealing to be time-saving, overcoming the need of sample pre-treatment steps. Detection limits were 154.8 ng mL⁻¹ by HPLC-UV, 118.0 ng mL⁻¹ by HPLC-FL and 48.0 ng mL⁻¹ by HPLC-MS. Trans resveratrol has been then quantified in a group of 52 wines derived from different Italian regions, cultivars and winemaking technologies by HPLC-UV.     

Electrooxidative coupling of salts of nitro compounds with halide,nitrite, cyanide,and phenylsulfinate anions

Electrolysis of salts of primary and secondary nitro compounds (nitroethane, 1- and 2-nitropropanes, nitrocyclohexane, and nitrocycloheptane) in the presence of excess halide, nitrite, cyanide, and phenylsulfinate anions under undivided and divided amperostatic electrolysis conditions in a two-phase medium (CH₂Cl₂/H₂O) produces geminal nitrohalides (35–85% yields), dinitro compounds (15–51%), nitronitriles (6–27%), and nitrosulfones (50–70%). The salts of secondary nitro compounds form the products of oxidative coupling with halide and phenylsulfinate anions under the undivided electrolysis conditions. In all other cases, divided electrolysis is required. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1539–1546, July, 2005.     

Core/shell particles containing 3-(methacryloxypropyl)-trimethoxysilane in the shell: synthesis, characterization, and application

In comparison to the corresponding single-component counterparts, core/shell particles are widely used due to their better physical and chemical properties. The surface properties of core/shell particles evidently play an important role in the process of application. It is easy to deduce that surface properties mostly depend on the properties of the component in the shell. Therefore, desirable materials of shell are very significant for the study of composite materials, especially in core/shell field. It is well known that polysiloxane has excellent properties, such as the water repellency, high flexibility, low surface energy, and biocompatibility. Its application, however, is limited due to poor cohesiveness and poor film-forming properties. Recently, much endeavor has been made to overcome such flaws. It is found that polyacrylate is commonly considered for its good cohesiveness and excellent film-forming property. The combination of polysiloxane and polyacrylate has been shown to be important in the composite material field, especially as core/shell particles. Unfortunately, their hydrophobicity is considerably different and thus, the core/shell particles consisting of polyacrylate (PA)/polysiloxane (PSi) are hard to prepare by general seeded emulsion polymerization, and are also scarcely available in the literature. In this study, the new core/shell PA/PSi particles with poly(butyl methacrylate) (PA) as the core and poly(3-(methacryloxypropyl)-trimethoxysilane) (PSi) as the shell were prepared by dispersion polymerization under the kinetically controlled conditions. The characterization of the particles by TEM, DSC, particle size analyzer as well as static contact angle confirmed the formation of core/shell structure. The application of core/shell (PA/PSi) particles also has been considered and discussed here.TEM micrographs of core/shell (PA/PSi) particles.     

High temperature corrosion behaviour of M(Co,Ni)CrAIY-coatings on high temperature materials-microanalytical investigations

In our former investigations, the phenomenon high temperature corrosion (HTC) was described exemplarily on selected materialcoating combinations for blades of stationary gas turbines, mainly in the temperature region of up to 750° C. To answer the question, in which manner higher gas inlet and/or higher material surface temperature would influence the HTC behaviour, a special analytical technique—the integral layer profile analysis—was introduced to ameliorate concentration profile methods. By examining IN 738 LC specimens with CoCrAlY plasma spray coating, stressed by hot gas at 900° C, the limits of this system are shown by explaining the corrosion mechanism; the method is also used for other systems, e.g. U 520 with NiCrAlY coating at 750° C.