Mesoporous Carbons of Well-Organized Structure in the Removal of Dyes from Aqueous Solutions

Mesoporous carbons with differentiated properties were synthesized by using the method of impregnation of mesoporous well-organized silicas. The obtained carbonaceous materials and microporous activated carbon were investigated by applying different methods in order to determine their structural, surface and adsorption properties towards selected dyes from aqueous solutions. In order to verify applicability of adsorbents for removing dyes the equilibrium and kinetic experimental data were measured and analyzed by applying various equations and models. The structural and acid-base properties of the investigated carbons were evaluated by Small-Angle X-ray Scattering (SAXS) technique, adsorption/desorption of nitrogen, potentiometric titration, and Transmission Electron Microscopy (TEM). The results of these techniques are complementary, indicating the type of porosity and structural ordering, e.g., the pore sizes determined from the SAXS data are in good agreement with those obtained from nitrogen sorption data. The SAXS and TEM data confirm the regularity of mesoporous carbon structure. The adsorption experiment, especially kinetic measurements, reveals the utility of mesoporous carbons in dye removing, taking into account not only the adsorption uptake but also the adsorption rate.     

Pulse radiolysis of 9-anthrylmethylammonium cation in aqueous solution

The reaction of hydrated electron with 9-anthrylmethylammonium cation to form the respective anthracene radical anion in aqueous solution has been studied by the method of pulse radiolysis. The rate constant of the reaction of with is reported. It is demonstrated that the anthracene radical anion is unstable and undergoes further reactions. The spectra of transient intermediates, leading to the final reduction products, are presented.     

Characteristics of glucose electrode with enzyme immobilised on nylon net

Glucose oxidase was immobilised on nylon net by the method of O-alkylation using dimethyl sulfate and lysine as a spacer. The influence of alkylation conditions on the characteristics of the resulting glucose electrode was evaluated. The best electrode was then tested under batch and flow conditions, respectively. The influence of pH and temperature on electrode response were examined. The glucose oxidase immobilised on nylon net seemed to be inhibited by glucose in alkaline pH and at higher temperatures. Moreover, the shape of the electrode signal after addition of glucose was unusual. Glucose oxidase immobilised on nylon net was unstable and lost its activity rather quickly, especially when stored dry in the refrigerator. Also the operational stability of the electrode in the flow system was rather poor.     

The pseudopotential-CI study of the interaction between ethylene and metal atoms,metal Oxides,and their cations (Me = Be,Mg, and Zn)

Potential energy curves for the lowest singlet and triplet states of Me + C₂H₄, Me⁺ + C₂H₄, MeO, MeO + C₂H₄, and (MeO + C₂H₄)⁺ systems for Me = Be, Mg, and Zn have been determined employing PP-MRD-CI or an all electron MRD-CI procedure. A binding interaction in the ground state has been found for oxides, all cation systems, and the BeO + C₂H₄ system. In the cases of MgO + C₂H₄ and ZnO + C₂H₄, only low lying excited states exhibit attractive interactions. Among three oxides considered, BeO is less pronounced biradically than MgO and ZnO. In order to obtain a binding interaction between an oxide and the olefin in the ground state, the p orbital of the metal must be sufficiently involved in binding.     

DSC study of linolenic acid autoxidation inhibited by BHT,dehydrozingerone and olivetol

Non-isothermal oxidation of linolenic acid (LNA) in bulk phase was monitored by differential scanning calorimetry. The kinetic parameters E _a, Z and k (activation energies, pre-exponential factors, and rate constants, respectively) were calculated by Ozawa-Flynn-Wall method for the first detectable exothermic effect of uninhibited LNA oxidation. The kinetic parameters were also calculated for LNA oxidation inhibited by 2,6-di-tert-butyl-4-methylphenol (BHT), and two natural compounds, 1,3-dihydroxy-5-pentylbenzene (olivetol), and 4-(4’-hydroxy-3’-methoxyphenyl)-3-buten-2-one (DHZ, dehydrozingerone) at various concentrations. For oxidation processes at 25, 90 and 180°C the plots of logk values vs. concentration of phenolic compounds indicated that optimal concentration of inhibitor determined for one particular temperature cannot be extrapolated to other temperatures.     

Non-equivalent water molecules in [Ni(H2O)6](ClO4)2 and in [Ni(D2O)6](ClO4)2 in the thermogravimetric investigations

The thermal decomposition of [Ni(H₂O)₆](ClO₄)₂ and [Ni(D₂O)₆](ClO₄)₂ were studied by thermogravimetric analysis (TG) and simultaneous differential thermal analysis (SDTA) at a constant heating rate. The gaseous products of the decomposition were on-line identified by a quadrupole mass spectrometer (QMS). In both cases the process of decomposition starts at ca. 410 K and is connected with removal of water molecules in a stepwise way; at the beginning the first water molecule is lost, then the second and at higher temperature the third one. The rest of the water molecules are lost in the temperature region of ClO₄⁻ decomposition. The energy of activation of the process was calculated in both cases.     

Application of gallium film electrode for elimination of copper interference in anodic stripping voltammetry of zinc

For elimination of copper interference in anodic stripping determinations of zinc at mercury and bismuth film electrodes gallium ions are usually added to the supporting electrolyte. In the presented studies novel ex situ formed gallium film electrode was applied for this purpose. The proposed electrode is less toxic than mercury one while the detection limit for zinc was lower than for bismuth film electrode following the same deposition time. The calibration graph for deposition time of 60 s was linear from 5 × 10⁻⁸ to 2 × 10⁻⁶ mol L⁻¹. The determinations of zinc were carried out from undeaerated solutions. The proposed procedure was applied to zinc determination in certified reference material and tap water sample.     

Tungsten electrode for urea

Tungsten electrodes for urea were prepared via covalent linking of urease on oxidized metal surfaces in different ways. The most stable electrodes were obtained when tungsten was silanized and activated by glutaraldehyde or hexamethylene diisocyanate. The electrode with urease coupled via glutaraldehyde was tested for optimum conditions of use. The nature of the buffer and its concentration and ionic strength are particularly important.     

Resveratrol Analogues as Selective Estrogen Signaling Pathway Modulators: Structure–Activity Relationship

Resveratrol is a plant-derived phytoalexin found in grapes, red wine and many other plants used in Asian folk medicine. It is extensively studied for pleiotropic biological activity. The most crucial are anticancer and chemopreventive properties. Resveratrol has also been reported to be an antioxidant and phytoestrogen. The phytoestrogenic activity of resveratrol was assayed in different in vitro and in vivo models. Although these works brought some, on the first look, conflicting results, it is commonly accepted that resveratrol interacts with estrogen receptors and functions as a mixed agonist/antagonist. It is widely accepted that the hydroxyl groups are crucial for resveratrol’s cytotoxic and antioxidative activity and are responsible for binding estrogen receptors. In this work, we assayed 11 resveratrol analogues, seven barring methoxy groups and six hydroxylated analogues in different combinations at positions 3, 4, 5 and 3′,4′,5′. For this purpose, recombined estrogen receptors and estrogen-dependent MCF-7 and Ishikawa cells were used. Our study was supported by in silico docking studies. We have shown that, resveratrol and 3,4,4′5′-tetrahydroxystilbene, 3,3′,4,5,5′-pentahydroxystilbene and 3,3′,4,4′,5,5′-hexahydroxystilbene may act as selective estrogen receptor modulators.     

Copper- or manganese-doped ZnS quantum dots as fluorescent probes for detecting folic acid in aqueous media

3-Mercaptopropionic acid-capped core/shell ZnS:Cu/ZnS and ZnS:Mn/ZnS doped quantum dots (QDs) prepared through hydrothermal methods exhibit high photoluminescence intensity as well as good photostability. These water-dispersible nanoparticles exhibit high fluorescence sensitivity to folic acid due to the high affinity of the carboxylate groups and nitrogen atoms of folic acid towards the Zn surface atoms of the doped dots. Quenching of the fluorescence intensity of the QDs allows the detection of folic acid concentrations as low as 11 μM, thus affording a very sensitive system for the sensing of this biologically active molecule in aqueous solution. The possible quenching mechanism is discussed.