F(x,y)=A(x,y) \text+* B(x), x ? I, y ? CF(x,y)=A(x,y) \stackrel{*}{\text{+}} B(x),\qquad x \in I, y \in C 相似文献
184.
Marzena Białek Krystyna Czaja Ewelina Szydło 《Journal of polymer science. Part A, Polymer chemistry》2009,47(2):565-575
This article compares catalytic performance of ethylene polymerization in similar polymerization conditions of transition metal complexes having two ligands [O,N] (phenoxy‐imine) and having one tetradentate ligand [O,N,N,O] (salphen or salen). It is shown that the activity of both complex types as well as the product properties depend in the same way on the type of central metal in the complex and on the cocatalyst used. Although the type of ligand has some effect on the catalyst activity, yet it does not control the properties of the obtained products. The vanadium and zirconium complexes, irrespective of the cocatalyst used, yield linear polyethylene with high molecular weight (a few hundred thousand g/mol). Similar products are formed when titanium complexes activated with MAO are employed. On the other hand, the same titanium complexes in conjunction with Et2AlCl, yield low molecular weight polyethylene (of a few thousand) and additionally a mixture of oligomers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 565–575, 2009 相似文献
185.
186.
Sylwia Zieliska Magdalena Dzigwa-Becker Adam Junka Ewelina Pitczak Anna Jezierska-Domaradzka Malwina Broyna Justyna Paleczny Aleksandra Sobiecka Wojciech Supski Eleonora Mess Mariusz Kucharski Serhat Sezai iek Christian Zidorn Adam Matkowski 《Molecules (Basel, Switzerland)》2021,26(16)
The antimicrobial properties of herbs from Papaveraceae have been used in medicine for centuries. Nevertheless, mutual relationships between the individual bioactive substances contained in these plants remain poorly elucidated. In this work, phytochemical composition of extracts from the aerial and underground parts of five Papaveraceae species (Chelidonium majus L., Corydalis cava (L.) Schweigg. and Körte, C. cheilanthifolia Hemsl., C. pumila (Host) Rchb., and Fumaria vaillantii Loisel.) were examined using LC-ESI-MS/MS with a triple quadrupole analyzer. Large differences in the quality and quantity of all analyzed compounds were observed between species of different genera and also within one genus. Two groups of metabolites predominated in the phytochemical profiles. These were isoquinoline alkaloids and, in smaller amounts, non-phenolic carboxylic acids and phenolic compounds. In aerial and underground parts, 22 and 20 compounds were detected, respectively. These included: seven isoquinoline alkaloids: protopine, allocryptopine, coptisine, berberine, chelidonine, sanguinarine, and chelerythrine; five of their derivatives as well as non-alkaloids: malic acid, trans-aconitic acid, quinic acid, salicylic acid, trans-caffeic acid, p-coumaric acid, chlorogenic acid, quercetin, and kaempferol; and vanillin. The aerial parts were much richer in phenolic compounds regardless of the plant species. Characterized extracts were studied for their antimicrobial potential against planktonic and biofilm-producing cells of S. aureus, P. aeruginosa, and C. albicans. The impact of the extracts on cellular metabolic activity and biofilm biomass production was evaluated. Moreover, the antimicrobial activity of the extracts introduced to the polymeric carrier made of bacterial cellulose was assessed. Extracts of C. cheilanthifolia were found to be the most effective against all tested human pathogens. Multiple regression tests indicated a high antimicrobial impact of quercetin in extracts of aerial parts against planktonic cells of S. aureus, P. aeruginosa, and C. albicans, and no direct correlation between the composition of other bioactive substances and the results of antimicrobial activity were found. Conclusively, further investigations are required to identify the relations between recognized and unrecognized compounds within extracts and their biological properties. 相似文献
187.
Ksepko Ewelina Klimontko Joanna Kwiecinska Anna 《Journal of Thermal Analysis and Calorimetry》2019,138(6):4247-4260
The paper contains the results of a study on a promising combustion technology known as chemical looping combustion (CLC). The main advantage of CLC is the production of a highly concentrated CO2 stream without any energy penalty for its separation, together with NOx emissions reduction. The objective of this work was to examine novel oxygen carrier (OC) materials for their practical applications with gaseous fuel/air. We report a simple, economical and environmentally friendly method for the large-scale synthesis of OCs from wastes. The reactivity tests for OCs made from wastewater from a coking plant were performed in a thermogravimetric analyser. For selected temperatures, reduction–oxidation cycles were performed. The effect of temperature on the reaction rates, the effect of waste treatment and the oxygen transport capacity were determined. The waste material demonstrated good thermal stability and maintained its redox behaviour over cycling. ICP-OES and XRD data revealed these materials that contained beneficial amounts of Fe species and silicon oxide, which improved stability. The study showed that these waste materials are excellent examples of raw materials that can enable a decrease in OC production costs with the additional benefit of the practical management of post-wastewater sediments from coke oven wastewater plants. 相似文献188.
The stereoselective properties of modified thiourea organocatalysts were tested in the Friedel–Crafts alkylation of indole with 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones, which produces chiral 5-((1H-indol-3-yl)(aryl)methyl)-2,2-dimethyl-1,3-dioxane-4,6-diones. Based on a tentative reaction mechanism for ((S)-N-benzyl-2-(3-(3,5-bis(trifluoromethyl)phenyl)thioureido)-N,3,3-trimethylbutanamide organocatalysts, modifications were applied in four selected regions. Systematic structure-stereoselectivity relationship study allowed designing the best efficient organocatalyst for the investigated Friedel–Crafts alkylation of indole with 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones. 相似文献
189.
Katarzyna Grelewska-Nowotko Magdalena Żurawska-Zajfert Ewelina Żmijewska Sławomir Sowa 《Applied biochemistry and biotechnology》2018,185(1):207-220
In recent years, digital polymerase chain reaction (dPCR), a new molecular biology technique, has been gaining in popularity. Among many other applications, this technique can also be used for the detection and quantification of genetically modified organisms (GMOs) in food and feed. It might replace the currently widely used real-time PCR method (qPCR), by overcoming problems related to the PCR inhibition and the requirement of certified reference materials to be used as a calibrant. In theory, validated qPCR methods can be easily transferred to the dPCR platform. However, optimization of the PCR conditions might be necessary. In this study, we report the transfer of two validated qPCR methods for quantification of maize DAS1507 and NK603 events to the droplet dPCR (ddPCR) platform. After some optimization, both methods have been verified according to the guidance of the European Network of GMO Laboratories (ENGL) on analytical method verification (ENGL working group on “Method Verification.” (2011) Verification of Analytical Methods for GMO Testing When Implementing Interlaboratory Validated Methods). Digital PCR methods performed equally or better than the qPCR methods. Optimized ddPCR methods confirm their suitability for GMO determination in food and feed. 相似文献
190.
Marta Ewelina Kobusińska Maria Witt Leszek Łęczyński 《International journal of environmental analytical chemistry》2018,98(5):453-476
This study comprises optimisation of sample preparation and HPLC analytical procedure for the determination of a personal care product ingredient, triclosan (TCS), in marine sediments. The testing of several varying pre-treatment parameters confirmed that ultrasonic extraction is an effective method for the isolation of TCS from marine sediments, and that the choice of extraction solvent appeared to be of major importance. The selection of the mobile-phase composition and the absorption wavelength was made for the high-performance liquid chromatography analysis step. Based on the validated method, a preliminary assessment of the benthic ecosystem quality with regards to TCS contamination has been demonstrated in the southern Baltic Sea – a semi-enclosed sea, characterised by poor water exchange, thus particularly susceptible to anthropopression. TCS has been identified and quantified in situ in marine bottom sediments, sediment dwelling isopod – Saduria entomon L. and estimated in silico in pore waters based on the equilibrium partition theory in order to assess the potential exposure and uptake from the aqueous phase. TCS concentrations identified in the bottom sediments of the Gdansk Basin, as the natural habitat for studied S.entomon L., appear to be threatening to the benthic environment. Particularly when considering S. entomon L. as a major nutrition source for cod (Gadus morhua) undergoing the feminisation process, since the recent studies prove TCS to have a potential to induce critical alterations in the endocrine system of marine ichthyofauna. 相似文献
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