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101.
Karolina Komisarz Tomasz M. Majka Monika Kurczab Krzysztof Pielichowski 《Molecules (Basel, Switzerland)》2022,27(21)
Lignin, a highly aromatic macromolecule building plant cells, and cellulose are two of the most commonly occurring natural polymers. Lignosulfonate is a grade of technical lignin, obtained as a by-product in the paper and wood pulping industries, a result of the used lignin isolation method, i.e., sulfite process. In this work, sodium lignosulfonate is used as a starting material to manufacture sulfonamide derivatives of lignin in a two-step modification procedure. Since this direction of the lignin modification is rather rarely investigated and discussed, it makes a good starting point to expand the state of knowledge and explore the properties of lignosulfonamides. Materials obtained after modification underwent characterization by FTIR, SS-NMR, WAXD, SEM, and TGA. Spectroscopic measurements confirmed the incorporation of dihexylamine into the lignin structure and the formation of lignosulfonamide. The crystalline structure of the material was not affected by the modification procedure, as evidenced by the WAXD, with only minute morphological changes of the surface visible on the SEM imaging. The obtained materials were characterized by improved parameters of thermal stability in relation to the raw material. As-prepared sulfonamide lignin derivatives with a potential application as a filler in biopolymeric composites may become a new class of functional, value-added, sustainable additives. 相似文献
102.
This work demonstrates the suitability of a newly developed ionic liquid (IL)-based silica SPME fiber for the determination of seven organophosphorus insecticides in cucumber and grapefruit samples by headspace solid-phase microextraction (HS-SPME) with a gas chromatography–flame ionization detector (FID). The sol-gel method released four different sorbent coatings, which were obtained based on a silica matrix containing ILs immobilized inside its pores. In order to obtain ionogel fibers, the following ionic liquids were utilized: 1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide; Butyltriethyl ammonium bis(trifluoromethylsulfonyl)imide; 1-(2-Methoxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and 1-Benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The developed fibers were applied for the extraction of seven different insecticides from liquid samples. The most important extraction parameters of HS-SPME coupled with the GC-FID method were optimized with a central composite design. The new SPME fiber demonstrated higher selectivity for extracting the analyzed insecticides compared with commercially available fibers. The limit of detection was in the range of 0.01–0.93 μg L−1, the coefficients of determination were >0.9830, and 4.8–10.1% repeatability of the method was found. Finally, the obtained ionogel fibers were utilized to determine insecticides in fresh cucumber and grapefruit juices. 相似文献
103.
Karolina Dzedulionyt Melita Veikait Vít Morvek Vida Malinauskien Greta Ra
kauskien Algirdas a
kus Asta
ukauskait Egl Arba
iauskien 《Molecules (Basel, Switzerland)》2022,27(24)
A general approach towards the synthesis of tetrahydro-4H-pyrazolo[1,5-a][1,4]diazepin-4-one, tetrahydro[1,4]diazepino[1,2-a]indol-1-one and tetrahydro-1H-benzo[4,5]imidazo[1,2-a][1,4]diazepin-1-one derivatives was introduced. A regioselective strategy was developed for synthesizing ethyl 1-(oxiran-2-ylmethyl)-1H-pyrazole-5-carboxylates from easily accessible 3(5)-aryl- or methyl-1H-pyrazole-5(3)-carboxylates. Obtained intermediates were further treated with amines resulting in oxirane ring-opening and direct cyclisation—yielding target pyrazolo[1,5-a][1,4]diazepin-4-ones. A straightforward two-step synthetic approach was applied to expand the current study and successfully functionalize ethyl 1H-indole- and ethyl 1H-benzo[d]imidazole-2-carboxylates. The structures of fused heterocyclic compounds were confirmed by 1H, 13C, and 15N-NMR spectroscopy and HRMS investigation. 相似文献
104.
Rafał Pelka Karolina Kiełbasa Walerian Arabczyk 《Central European Journal of Chemistry》2011,9(2):240-244
Iron catalyst for ammonia synthesis of various mean sizes of iron nanocrystallites were nitrided with ammonia in a differential
reactor equipped with systems that made it possible to conduct both thermogravimetric measurements and hydrogen concentration
analyses in the reacting gas mixture. The nitriding process was investigated under atmospheric pressure at the temperature
of 475°C. It was found that along with an increase of mean size of iron nanocrystallites, with a decrease of specific surface
area of the samples, nitriding degree of solid samples increased. At the same time the rate of surface reaction of catalytic
ammonia decomposition decreased. Along with an increase of the samples’ specific surface area an increase of the catalyst’s
activity was observed. However, it was also observed that the concentration of active sites on the catalysts’ surface decreased
along with an increase of specific surface area. 相似文献
105.
106.
Filip Ciesielczyk Karolina Szwarc‐Rzepka Teofil Jesionowski 《Surface and interface analysis : SIA》2013,45(6):998-1007
Preparation of a new group of hybrid fillers, of SiO2/silane/oligomeric silsesquioxane type, characterised by specific desirable physicochemical properties, was studied. Synthetic SiO2 was precipitated by the emulsion method. At first, as a result of improved adhesion between SiO2 and selected POSS compound, SiO2 surface was functionalised with alkoxysilanes containing characteristics functional groups. Functionalised SiO2 was used in the process of hybrid filler preparation according to hydrolytic condensation using methacryl POSS® mixture. To evaluate potential application of such fillers, SiO2 systems, bifunctionalised using innovative method, were thoroughly characterised to determine their physicochemical properties as well as the effectiveness of functionalisation with silanes and POSS compound. Proposed method of SiO2 surface modification using selected alkoxysilanes and oligosilsesquioxanes is innovative and gives very promising results. Bifunctionalisation of inorganic fillers with those compounds will substantially extended the range of their applications and probably will lead to improvement of mechanical properties of final polymer composites and reduction in the cost of their production which is the main feature of this research. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
107.
Kaszuba Natalia Kasprzyk-Kucewicz Teresa Bałamut Karolina Morawiec Tadeusz Stanek Agata Wziątek-Kuczmik Daria Cholewka Armand 《Journal of Thermal Analysis and Calorimetry》2022,147(12):6745-6753
Journal of Thermal Analysis and Calorimetry - The main goal of this study was to find out if thermal imaging may be useful in the evaluation of two types of anaesthetic injections—with and... 相似文献
108.
Marius Dagys Karolina Haberska Sergey Shleev Thomas Arnebrant Juozas Kulys Tautgirdas Ruzgas 《Electrochemistry communications》2010,12(7):933-935
It was found that homogeneous activity of Trametes hirsuta laccase is considerably diminished in the presence of gold nanoparticles (Au-NPs). Heterogeneous electron transfer studies revealed that Au-NPs facilitate direct electron transfer (DET) between the T1 copper site of the laccase and the surface of Au-NP modified electrodes. DET was characterized by the standard heterogeneous ET constant of 0.5 ± 0.6 s?1 at Au-NPs with an average diameter of 50 nm. As a consequence of this a well pronounced DET based bioelectrocatalytic oxygen reduction with current densities of 5–30 µA cm?2 has been achieved at the laccase–Au-NP modified electrodes. 相似文献
109.
Karolina Kędra-Królik Małgorzata Wszelaka-Rylik Paweł Gierycz 《Journal of Thermal Analysis and Calorimetry》2010,101(2):533-540
The way of precipitation process conducting is crucial for the final product properties and its further applications. In present
experiments, the CaCO3 powders, produced by controlled fast precipitation trough gaseous CO2 absorption in Ca(OH)2 slurry, have been covered by two fatty acids: dodecanoic (lauric) acid and tetradecanoic (myristic) acid. This multiphase
reaction was conducted in a new rotating disc reactor unit which enables to control inter- and intra-face mass and energy
transfer as well as the macro- and micromixing effects in the reacting system. The obtained nanopowders have been observed
by the use of the scanning electron microscope. The X-ray diffraction technique as well as the dynamic light scattering (DLS)
and the thermogravimetric method (TG) were further used for its deep analyses. The experimental data have allowed for distinction
between different fatty acid molecules species present on calcite surface (chemisorbed ones, inter-located between adsorbed
to surface, formed mono- and bilayers and the soap) or free fatty acids molecules if presented in the sample. The amount of
fatty acid species forming different layers on calcite as well as the size and distribution of fatty acid coated CaCO3 powders have been also calculated. 相似文献
110.
Caban K Lewera A Zukowska GZ Kulesza PJ Stojek Z Jeffrey KR 《Analytica chimica acta》2006,575(1):144-150
Two methods have been used for examination of transport of charge in gels soaked with DMF and containing dissolved polyoxometallates. The first method is based on the analysis of both Cottrellian and steady-state currents and therefore is capable of giving the concentration of the electroactive redox centres and their transport (diffusion-type) coefficient. The second method provides the real diffusion coefficients, i.e. transport coefficients free of migrational influence, for both the substrate and the product of the electrode reaction. Several gels based on poly(methyl methacrylate), with charged (addition of 1-acrylamido-2-methyl-2-propanesulphonic acid to the polymerization mixture) and uncharged chains, have been used in the investigation. The ratio obtained for the diffusion coefficient (second method) and transport coefficient (first method) was smaller for the gels containing charged polymer chains than for the gels with uncharged chains. In part these changes could be explained by the contribution of migration to the transport of polyoxomatallates in the gels. However, the impact of the changes in the polymer-channel capacity at the electrode surface while the electrode process proceeds was also considered. These structural changes should affect differently the methods based on different time domains. 相似文献