Photocatalytic TiO2 Coatings: Effect of Substrate and Template

Summary. Transparent TiO₂ films with a high photodegradation activity towards an azo dye in aqueous solution were prepared by sol–gel processing. Films on soda–lime glass supports protected with a thin silica barrier layer exhibited better crystallization and monodisperse nanoparticles, higher absorption of light below 370 nm, and higher photocatalytic activity than those films deposited on bare glass supports proving the detrimental effect of interdiffused sodium ions on the development of the anatase nanostructure. The effect of substrate was more pronounced in thinner films (300 nm) than in thicker ones (1200 nm), which were achieved by adding a template (i.e. Pluronic F127) to the sol.     

Photocatalytic TiO2 Coatings: Effect of Substrate and Template

Transparent TiO₂ films with a high photodegradation activity towards an azo dye in aqueous solution were prepared by sol–gel processing. Films on soda–lime glass supports protected with a thin silica barrier layer exhibited better crystallization and monodisperse nanoparticles, higher absorption of light below 370 nm, and higher photocatalytic activity than those films deposited on bare glass supports proving the detrimental effect of interdiffused sodium ions on the development of the anatase nanostructure. The effect of substrate was more pronounced in thinner films (300 nm) than in thicker ones (1200 nm), which were achieved by adding a template (i.e. Pluronic F127) to the sol.     

Simply Applicable Method for Microplastics Determination in Environmental Samples

Microplastics (MPs) have gained significant attention in the last two decades and have been widely researched in the marine environment. There are, however, less studies on their presence, routes of entry, and impacts on the biota in the soil environment. One of the main issues in the study of MPs is a lack of standardized methods for their identification in environmental samples. Currently the most commonly used techniques are thermal desorption gas chromatography–mass spectrometry (GC–MS) methods and pyrolysis followed by GC–MS. In this study, headspace-solid phase microextraction followed by GC–MS is proposed as a simple and widely applicable method for the determination of commonly present polymer MPs (polyethylene terephthalate, polystyrene, polyvinyl chloride, polyethylene, and polypropylene) in environmental samples, for analytical laboratories with basic equipment worldwide. The proposed method is based on the identification of compounds, which are formed during the well-controlled melting process of specific coarse (1–5 mm) and fine fraction (1 mm–100 μm) MPs. The method was upgraded for the identification of individual polymer type in blends and in complex environmental matrices (soil and algae biomass). The successful application of the method in complex matrices makes it especially suitable for widescale use.     

Selective synthesis of some 5-hydrazono-5,6,7,8-tetrahydro-2H-1-benzopyran-2-ones

A simple, highly selective transformation of 5,6,7,8-tetrahydro-2H-1-benzopyran-2,5-diones 1–3 and 14 with some phenylhydrazines and heterocyclic hydrazines to 5-hydrazono-2H-1-benzopyran-2-ones 4–12 and 15–16 is described. Under more severe conditions the hydrazonoquinoline derivative 17 was obtained from the benzopyran derivative 3 and Phenylhydrazine.     

Study of the Chlorination of Avobenzone in Sea Water by Gas Chromatography–High Resolution Mass Spectrometry

Disinfection is an important step in the purification of drinking and swimming pool water. The most common procedure includes chlorination, which efficiently eliminates microorganisms. However, the reaction of active chlorine with dissolved organic matter produces numerous organochlorine compounds posing a hazard to the environment and human health. UV filters belong to emerging contaminants, as their application to skin protection from UV irradiation becomes increasingly popular all over the world. Certain components of UV filters were detected in swimming pools and result in the emergence of new ecotoxicants. In the present study, 40 compounds, including numerous brominated derivatives, which result from the chlorination of avobenzone in sea water, were identified by gas chromatography–high resolution mass spectrometry. In addition, the applicability of photocatalysis to the destruction of chlorination products was studied. The procedure was found to be rather efficient and allows a decrease in the total amount of avobenzone transformation products by a factor of 10. The only compound class demonstrating stability under the applied conditions is exemplified by halogenated acetophenone derivatives.     

Characterization of Al(III) complexes with hematein in artistic alum logwood inks

The complexes between Al(III) and hematein, the main coloring matter in alum logwood inks, were characterized by Raman and ²⁷Al NMR (nuclear magnetic resonance) spectroscopies. Raman spectra of the crystallized complexes and of the compounds applied on a paper substrate are presented and assigned based on published data for the parent compounds. These Raman spectra show that the coordination of the hematein to the Al(III) ions takes place in both cases through the carbonyl and hydroxyl groups in the molecule, and that the aromatic rings are also involved in the interaction. The Raman spectra of the pure hematein–Al(III) complexes were found to be consistent with those recorded for a logwood ink prepared following a late 19th century recipe, using logwood chips instead of pure hematein, and applied on a paper substrate. These spectra can be used as references for the noninvasive identification of the compounds in works of art. ²⁷Al solid‐state NMR showed that the coordination of the Al(III) atoms in the crystallized powder is predominantly octahedral, while when applied on a paper substrate the colorant is present mainly as a tetrahedral complex, with an octahedral coordination also present in a smaller proportion. The fact that the predominant coordinations for the complexes in the crystallized material and for the ones present on the paper substrate are different is relevant for the study of the lightfastness and thermal stability of works of art bearing these media. Copyright © 2009 John Wiley & Sons, Ltd.     

EThcD Discrimination of Isomeric Leucine/Isoleucine Residues in Sequencing of the Intact Skin Frog Peptides with Intramolecular Disulfide Bond

Our scientific interests involve de novo sequencing of non-tryptic natural amphibian skin peptides including those with intramolecular S–S bond by means of exclusively mass spectrometry. Reliable discrimination of the isomeric leucine/isoleucine residues during peptide sequencing by means of mass spectrometry represents a bottleneck in the workflow for complete automation of the primary structure elucidation of these compounds. MS³ is capable of solving the problem. Earlier we demonstrated the advanced efficiency of ETD-HCD method to discriminate Leu/Ile in individual peptides by consecutive application of ETD to the polyprotonated peptides followed by HCD applied to the manually selected primary z-ions with the targeted isomeric residues at their N-termini and registration of the characteristic w-ions. Later this approach was extended to deal with several (4–7) broad band mass ranges, without special isolation of the primary z-ions. The present paper demonstrates an advanced version of this method when EThcD is applied in the whole mass range to a complex mixture of natural non-tryptic peptides without their separation and intermediate isolation of the targeted z-ions. The proposed EThcD method showed over 81% efficiency for the large natural peptides with intact disulfide ring, while the interfering process of radical site migration is suppressed. Due to higher speed and sensitivity, the proposed EThcD approach facilitates the analytical procedure and allows for the automation of the entire experiment and data processing. Moreover, in some cases it gives a chance to establish the nature of the residues in the intact intramolecular disulfide loops.

Open image in new window

Graphical Abstract ?

     

The Influence of Malathion and Its Decomposition Products on Free and Immobilized Acetylcholinesterase1

The influence of malathion and its four main degradation products found in irradiated solutions (malaoxon, isomalathion, diethyl maleate and O,O-dimethyl phosphate) on acetylcholinesterase (AChE) of free and immobilized bovine erythrocytes was investigated. The concentration-dependent responses to malathion and related organophosphates, malaoxon and isomalathion, of both AChE bioassays used were obtained. The IC ₅₀ values for free and immobilized AChE (3.7 ± 0.2) × 10⁻⁴ M/(1.6 ± 0.1) × 10⁻⁴, (2.4 ± 0.3) × 10⁻⁶/(3.4 ± 0.1) × 10⁻⁶ M, and (3.2 ± 0.3) × 10⁻⁶ M/(2.7 ± 0.2) × 10⁻⁶ M were obtained in the presence of malathion, malaoxon and isomalathion, respectively. However, diethyl maleate inhibited AChE activity at concentrations ≥ 10 mM, while O,O-dimethyl phosphate did not noticeably affect enzyme activity at all investigated concentrations. The relation between the structure of the compounds and their ability to inhibit enzyme activity was discussed. The article is published in the original.     

微量热法研究二价铅对两种不同土壤微生物的毒性作用

本次研究采用微量量热技术分析了铅对两种常见土壤微生物（假丝酵母菌、枯草杆菌）的毒性作用。实验结果表明,低浓度Pb(Ⅱ) (10.0 µg mL-1) 对两种土壤微生物的生长均有促进作用;而当Pb(Ⅱ) 浓度较高时（假丝酵母菌 20.0~320.0 µg mL-1、枯草杆菌20.0~160.0 µg mL-1）,微生物的生长则明显被抑制了,此时微生物的生长速率常数k与Pb(Ⅱ) 的浓度c呈现线性相关。同时,细胞干重法和浊度法也应用于本次研究中,并与微量量热曲线拟合,充分证明了微量量热技术对研究铅对土壤微生物毒性作用的准确性和有效性。