Jacek Rynkowski

Chromatographic methods in the study of autism

Research into biomarkers of autism is a new means of medical intervention in this disease. Chromatographic techniques, especially coupled with mass spectrometry, are widely used in determination of biomarkers and assessment of effectiveness of autism therapy owing to their sensitivity and selectivity. Among the chromatographic techniques gas chromatography and liquid chromatography, especially high-performance liquid chromatography, have found application in clinical trials. The high-performance liquid chromatography technique allows an analysis of liquid samples with a wide range of molecules, small and large, providing an opportunity to perform advanced assays within a short time frame. Gas chromatography with the appropriate preparation of samples (gaseous and liquid) and a selection of analysis conditions enables the separation of thermally stable, volatile and non-volatile organic substances in short runtimes. The chromatographic techniques that are currently used in metabolic studies in autism are designed to identify abnormalities in three areas: the metabolism of neurotransmitters, nutritional and metabolic status and manifestations of oxidative stress. This review presents a necessary theoretical introduction and examples of applications of chromatographic studies of disorder markers in autism.

Ceria-zirconia supported gold catalysts

Ceria-zirconia supported gold catalysts This paper presents the most important achievements and conclusions coming from the contributions concerning ceria-zirconia supported Au catalysts for low temperature water gas-shift reaction and low-temperature CO oxidation. The usefulness of CeO2-ZrO2 mixed oxides as supports for Au nanoparticles has been reviewed, mainly from the point of view of their contribution to those reactions. A special attention was paid to the active sites of CO oxidation and WGS reaction over Au/ceria-zirconia systems. Some aspects of the reactions mechanisms are also discussed. Ceriazirconia supported gold catalysts appear to be very promising systems, which have a potential to create a new quality in the catalysis of WGS reaction. Ceria-zirconia mixed oxides also seem to be very promising supports for Au nanoparticles in CO oxidation. They could find a practical application in ambient conditions, especially in air purification systems and a breathing apparatus. It is possible that gold could be usefully incorporated into automobile catalysts, considering that the price of other noble metals is rising rapidly. Their use in this application will, however, require demonstration of adequate stability at operating temperatures.

Electrochemical Reactions of Sodium 2-Ethylhexyl Sulfate Salt

AbstractThe electrochemical reactions of sodium 2-ethylhexyl sulfate (EHS) and its effect on the Zn2+ electroreduction have been investigated at a mercury electrode using cyclic voltammetry. It has been shown that the reduction takes place in two steps. The presence of EHS in the solution containing Zn2+ ions moves slightly the potential of zinc reduction towards more negative potentials and causes a slight increase in current density. The differential capacity-potential and differential capacity-time measurements indicate strong adsorption in a wide potential range on the electrode surface. In the potential range −0.46 to −0.86xa0V vs. saturated calomel electrode and at the concentration lower than the critical micelle concentration (CMC), adsorption for the longer time is hardly reversible. At the concentration higher than the CMC, the formation of hemispherical surface micelles is observed. The theoretical maximum degree of electrode coverage computed with the use of quantum-chemical calculations is equal to 3.53xa0×xa01014xa0particlesxa0cm−2, and it is larger than the value determined experimentally from cyclic voltammograms. In the case of electrochemical reaction, at a current of 0.3xa0A, during 180xa0min, the obtained mineralization of EHS is only 3%.n Graphical Abstract

Electrochemical, Photochemical, and Photoelectrochemical Treatment of Sodium p-Cumenesulfonate

The degradation of sodium p-cumenesulfonate (SCS) by electrochemical, photochemical, and photoelectrochemical methods in aqueous solution of NaClO4, NaCl, and NaClO has been studied. It was found that as a result of NaClO4 electroreduction and photodecomposition, the ions Cl− and ClO3− are formed. These ions undergo transformations into radicals, mainly Cl•, Cl2•−, ClO•−, ClO2•−, and ClO3•−, due to electrochemical and photochemical reactions. It was shown that the interpretation of results of the studies over mineralization processes carried out in the presence of ClO4− cannot be adequate without taking into consideration the reduction of ClO4− to Cl− and ClO3−. Therefore, previous works presented in the literature should be rediscussed on the basis of the new data. Photoelectrochemical mineralization of substrate in NaCl solution at the concentration of 16xa0mmolxa0L−1 is comparable with the efficiency of the reaction in NaClO4 solution containing more than 8xa0mmolxa0L−1 of NaClO. Total SCS mineralization was obtained in the photoelectrochemical reactor with a UV immersion lamp with a power 15xa0W in the period of 135xa0min and current intensity of 350xa0mA. In such conditions, the power consumption was about 1.2xa0kWh per g of TOC removed.

CO and H2 oxidation over Pt/BaSnO3 catalysts

This work reports the results of the studies on oxidation of carbon monoxide and H2 over Pt supported on barium stannate (BaSnO3—perovskite type oxide). The composition and properties of Pt/BaSnO3 catalysts were characterized by X-ray diffraction (XRD), time-of-flight secondary ion mass spectrometry (TOF–SIMS), H2 and CO chemisorption, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDS) and tested in the reactions of carbon monoxide and hydrogen oxidation. It was stated that platinum strongly interacts with BaSnO3. The catalytic activity and adsorption properties of Pt/BaSnO3 catalysts are determined by these interactions. The presence of different species (which generally can be labelled as [(Pt)BaSnO3]) resulting from platinum and BaSnO3 chemical interaction was found by the TOF–SIMS on surface of Pt/BaSnO3 catalysts. The mechanism of CO and H2 oxidation over Pt/BaSnO3 catalysts was discussed in the light of strong interactions between Pt and BaSnO3.

Photoelectrochemical Treatment of α,β-Unsaturated Ketones on TiO2-RuO2/Ti Electrode

The photoelectrochemical degradation of structurally similar α,β-unsaturated ketones such as 4-phenyl-3-buten-2-one (benzylideneacetone), 1-(p-totyl)-1-penten-3-one, 4-(p-totyl)-3-buten-2-one, and 4-mesityl-3-buten-2-one has been investigated. Their susceptibility to oxidation and reduction was determined on the basis of voltammetric measurements. It was found that the more methyl groups are attached to the aromatic ring, the oxidation and reduction occurs easier. Among electrodes with different molar ratio of TiO2 and RuO2 (also modified with transition metals oxides: Nb2O5, ZrO2, and Y2O3), TiO2 (70xa0%)-RuO2 (30xa0%)/Ti electrode was selected for photoelectrochemical reaction as the optimum one. The photocatalytic activity of the analyzed materials has been determined on the basis of the photocurrent generated in KCl and NaClO4 solutions. The highest mineralization was achieved for benzylideneacetone while the lowest was for 4-mesityl-3-buten-2-one using current intensity of 0.3xa0A and UV radiation with the wavelength of 254xa0nm during 120xa0min.

Photocatalytic CO oxidation with water over Pt/TiO2 catalysts

This paper reports that Pt/TiO2 and to some extent, Pt/Al2O3 and Pt/SiO2 catalysts show some activity in the photocatalytic oxidation of CO by water at low temperature (<xa0100xa0°C) in the absence of oxygen. For Pt/TiO2 catalysts, CO conversion is dependent on the Pt loading as well as the temperature of their reduction. There are an optimal platinum loading (5 wt%) and catalyst reduction temperature (500xa0°C) ensuring the best photocatalytic efficiency. Catalytic performance results from the combined effects of electron–hole photogeneration and partial photodesorption of CO from the platinum surface, followed by the adsorption and subsequent dissociation of H2O. The probable mechanism of photooxidation of CO by H2O was proposed.