Abatement of oxalates catalyzed by Fe-silica structured surfaces via cyclic carboxylate intermediates in photo-Fenton reactions

Novel silica/Fe structured fabrics were observed to degrade oxalates only under light irradiation showing the formation and disappearance of Fe-carboxylates and the concomitant recycling of the resulting Fe-ions back to the structured catalyst surface.     

Dielectric relaxation and ac conduction of AgTlTe2 amorphous semiconductor

Measurements of the dielectric properties of AgTlTe₂ in the solid and liquid states were carried out in a wide range of frequencies and temperatures. The material shows dielectric dispersion. Cole-Cole diagrams have been used to determine the distribution parameter and the molecular relaxation time. The ac conduction mechanism and dielectric loss are attributed to correlated barrier hopping in the amorphous solid.     

Rapid determination of salbutamol in pharmaceutical preparations by chiral capillary electrophoresis

A fast and simple method of chiral capillary electrophoresis (CE) has been applied to the analysis of salbutamol in different pharmaceutical preparations. Using of a 25 mM acetate buffer (pH 5.0), containing 13.1 mg/mL carboxymethyl-beta-cyclodextrin (CM-beta-CD), an applied voltage of 20 kV and a temperature of 25 degrees C, the enantiomers of salbutamol could be separated in about 2 min. Three different pharmaceutical preparations (two syrups, one oral solution, and two kind of tablets) containing a racemate of salbutamol were injected directly in the CE system, following dilution in dimethyl sulfoxide (DMSO). Appreciable differences in the retention times were observed for salbutamol enantiomers in the different formulations studied, which were attributed to the effect of the matrix components on the electrophoretic mobility. The standard addition method was used for the calibration due to the existence of matrix interferences. Finally, the stability of the enantiomers of salbutamol in the oral solution was studied calculating the enantiomeric ratio values when the solution was injected immediately after being opened in the first case and after being opened and stored in the fridge for two months in the second case.     

Preparation and characterization of carboxylic-containing poly(methyl methacrylate) nanolatexes

Poly(methyl methacrylate) (PMMA)-based latex particles bearing carboxylic groups at the surface were prepared via emulsion polymerization. The polymerization recipe and process were optimized in order to target monodisperse particles with diameters around 100 nm. The polymerizations were performed using 4,4-azobis(4-cyanopentanoic) acid (ACPA) as initiator and sodium dodecyl sulphate (SDS) as surfactant. The polymerization conversion was determined by both gas chromatography and gravimetry. The final latexes were characterized with respect to particle size, size distribution, surface charge density, electrokinetic properties (i.e. electrophoretic mobility vs pH and ionic strength) and colloidal stability (i.e. coagulation rate constants vs pH and stability factor vs ionic strength).     

Remarkable influence of surface composition and structure of oxidized iron layer on orange I decomposition mechanisms

Although the decomposition of water pollutants in the presence of metallic iron is known, the reaction pathways and mechanisms of the decomposition of azo-dyes have been meagerly investigated. The interface phenomena taking place during orange I decomposition have been investigated with the use of infrared external reflection spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The studies presented in this paper establish that there are close relationships between the composition and structure of the iron surface oxidized layers and the kinetics and reaction pathway of orange decomposition. The influence of the molecular structure of azo-dye on the produced intermediates was also studied. There are remarkable differences in orange I decomposition between pH 3 and pH 5 at 30 degrees C. Decomposition at pH 3 is very fast with pseudo-first-order kinetics, whereas at pH 5 the reaction is slower with pseudo-zero-order kinetics. At pH 3, only one amine, namely 1-amino-4-naphthol, was identified as an intermediate that undergoes future decomposition. Sulfanilic acid, the second harmful reduction product, was not found in our studies. At pH 3, the iron surface is covered only by a very thin layer of polymeric Fe(OH)(2) mixed with FeO that ensures orange reduction by a combination of an electron transfer reaction and a catalytic hydrogenation reaction. At pH 5, the iron surface is covered up to a few micrometers thick, with a very spongy and porous layer of lepidocrocite enriched in Fe(2+) ions, which slows the electron transfer process. The fastest decomposition reaction was found at a potential near -300 mV (standard hydrogen electrode). An addition of Fe(2+) ions to solution, iron preoxidation in water, or an increase of temperature all result in an increasing decomposition rate. There is no single surface product that would inhibit the decomposition of orange. This information is crucial to perform efficient, clean and low cost waste water treatment. The findings presented here make the treatment of wastewater in the presence of metallic iron a very promising solution.     

Efficiency of blocking of non-specific interaction of different proteins by BSA adsorbed on hydrophobic and hydrophilic surfaces

The efficiency of a pre-absorbed bovine serum albumin (BSA) layer in blocking the non-specific adsorption of different proteins on hydrophobic and hydrophilic surfaces was evaluated qualitatively and quantitatively using infrared reflection spectroscopy supported by spectral simulations. A BSA layer with a surface coverage of 35% of a close-packed monolayer exhibited a blocking efficiency of 90–100% on a hydrophobic and 68–100% on a hydrophilic surface, with respect to the non-specific adsorption of concanavalin A (Con A), immunoglobulin G (IgG), and staphylococcal protein A (SpA). This BSA layer was produced using a solution concentration of 1 mg/mL and 30 min incubation time. BSA layers that were adsorbed at conditions commonly employed for blocking (a 12 h incubation time and a solution concentration of 10 mg/mL) exhibited a blocking activity that involved competitive adsorption–desorption. This activity resulted from the formation of BSA–phosphate surface complexes, which correlated with the conformation of adsorbed BSA molecules that was favourable for blocking. The importance of optimisation of the adsorbed BSA layer for different surfaces and proteins to achieve efficient blocking was addressed in this study.     

New Quinic Acid Derivatives from Hepatoprotective Inula crithmoides Root Extract

Fractionation directed by hepatoprotective activity of Inula crithmoides L. root resulted in the isolation of two new quinic acid derivatives, 3,5‐di‐O‐caffeoylquinic acid 1‐methyl ether ( I ; caffeoyl=(E)‐3‐(3,4‐dihydroxyphenyl)prop‐2‐enoyl; quinic acid=1,3,4,5‐tetrahydroxycyclohexanecarboxylic acid) and 4,5‐di‐O‐caffeoylquinic acid 1‐methyl ether ( II ), in addition to the well‐known hepatoprotective compound, 1,5‐di‐O‐caffeoylquinic acid ( III ). The hepatoprotective effect was indicated by the significant decrease in the level of four measured serum biochemical parameters (SGOT, SGPT, ALP, and bilirubin) in experimental rats. The structures of the isolated compounds were determined by analyses of 1D‐ and 2D‐NMR spectroscopic data.     

MAOS of Sugar Phenylosazones and their Derived Pyrazoles and Triazoles

Microwave‐assisted organic synthesis (MAOS) has proven to be practical to provide heterocycles from sugar osazones; an efficient method was developed for the characterization of sugars via their osazones 1–4 using microwave irradiation. The microwave‐assisted organic synthesis irradiation technique has been applied to convert d‐arabino‐hexose phenylosazone to 2‐phenyl‐4‐(d‐arabinotetrahydroxybutyl‐1,2,3‐triazole (5), which was then oxidized to the corresponding aldehyde whose oxime 9 was transformed to 4‐cyano‐2‐phenyltriazole 10. The condensation of 7 with thiosemicarbozide gave 10. Degradation of 1 afforded mesoxaldehyde 1,2‐bisphenylhydrazone 11, which cyclized to 1‐phenyl‐4‐phenylazo‐pyrazole (12) under acidic conditions. Irradiation of 6 in HBr/AcOH afforded 4‐(d‐arabino‐2′,3′‐di‐O‐acetyl‐1′,4′‐dibromobutyl)‐2‐phenyl‐2H‐1,2,3‐triazole. The acetylated phenylosazone was converted to furopyridazine 14. The irradiation of phenylosazone with acetic anhydride in pyridine gave the respective O‐acetyl derivative, whereas with boiling acetic anhydride gave the pyrazole 14, which afforded 15 and 16.      

Viscosity of liquid selenium and selenium-sulphur mixtures

The viscosity of selenium has been studied in the liquid state, and the effect of thallium and sulphur additives was investigated. The rotating cylinder method was used. Experimental measurements show that the viscosity of liquid selenium with sulphur admixtures is higher than that for pure selenium, and a complex molecular structure is formed. The results were explained on the basis of the free volume model and the data for liquid selenium were fitted to the model withE _act=0.6 eV.     

Hopping transport in organic semiconductor system

The electrical conductivity of cupferron and some of its divalent transition metal complexes has been studied in the temperature range 0–150°C, in the amorphous state. An important result was found; namely that the temperature dependence of the conductivity is characteristic of the Mott hopping mechanism and identical with that of layers made by evaporating Ge, Si and carbon. It seems that only the physical structure determines the mechanism of conduction in amorphous materials, while the chemical composition is of minor importance.