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71.
Dobrzynski Maciej Herman Katarzyna Bryla Ewelina Fita Katarzyna Dudek Krzysztof Kowalczyk-Zajac Malgorzata Szymonowicz Maria Rybak Zbigniew Korczynski Mariusz Wiglusz Rafal J. 《Journal of Thermal Analysis and Calorimetry》2019,135(6):3123-3128
Journal of Thermal Analysis and Calorimetry - An use of a polymerization lamp to irradiate chemically hardened glass-ionomer materials may improve their properties and accelerate the setting time.... 相似文献
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Sakuntala Gupta Tanmay Choudhury Ewelina Dmochowska Przemysław Kula Fabio Borbone Roberto Centore 《Liquid crystals》2019,46(4):543-549
The title compound, 2,7-bis(4-pentylphenyl)-9,9-diethyl-9H-fluorene, is a new mesogenic compound containing the fluorene moiety. It exhibits a monotropic nematic liquid crystalline behaviour, with isotropisation temperature of 53°C. The compound is also polymorphic in the solid state, with one crystal phase melting at 103°C and another one melting at 71°C. The crystal and molecular structure of the high melting solid phase have been determined from single crystal X-ray diffraction analysis. Crystals are monoclinic, with cell dimensions a = 16.649(6) Å, b = 8.305(3) Å, c = 24.598(7) Å, β = 111.60(2)?, space group P21/c and four molecules in the unit cell. Refinement leads to R = 0.0558. The two terminal alkyl chains and one phenyl ring are disordered over two split positions. The imbricated molecular packing observed in the solid state seems to resemble that of the nematic phase that is formed upon cooling the melt. 相似文献
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Sakuntala Gupta Tanmay Choudhury Ewelina Dmochowska Przemyslaw Kula Fabio Borbone Roberto Centore 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(11):1459-1464
The title compound, C37H42, is a new mesogenic compound containing the fluorene moiety. It exhibits enantiotropic nematic liquid crystalline behaviour with melting at 125 °C and isotropization at 175 °C. The crystallographically independent unit contains two molecules oriented face‐to‐edge with respect to each other. The two molecules have nearly the same conformation of the bis‐phenyl fluorene moiety. The molecular packing in the crystal phase is nematic‐like. 相似文献
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Komsta Łukasz Pietraś Rafał Bartuzi Ewelina Skibiński Robert Gumieniczek Anna 《平面色谱法杂志一现代薄层色谱法》2015,28(2):115-118
JPC – Journal of Planar Chromatography – Modern TLC - Thin-layer chromatography (TLC) on two adsorbents (RP18 and CN) and with six modifiers (acetonitrile, acetone, dioxane, propan... 相似文献
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Photochromic properties of methylacrylate monomers and polymers containing azobenzene groups with heterocyclic sulfonamide
functionalities viz sulfisomidyne (4-amino-N-[2,6-dimethylpyrimidyn-4-yl]benzenesulfonamide) and sulfamethoxazole (4-amino-N-[5-methylisoxazol-3-yl]benzenesulfonamide)
substituents were investigated. On illumination with light the azobenzene group underwent trans-cis isomerisation, which was manifested by a drop in the absorbance of the maximum absorption peak at ca. 450 nm and by decrease in refractive index.
Quantum chemical calculations showed significant differences in UV-VIS spectra, dipole moments, polarizability and refractive
index between both cis and trans form of the chromophoric monomers.
The illumination of spin-coated polymer films during ellipsometry measurements resulted in a change in refractive index within
the range of 0.014 to 0.025. The dynamics of growth and decay of refractive index changes, was described by biexponential
functions approach. 相似文献
79.
Essential plants, due to their long presence in human history, their status in culinary arts, their use in medicine and perfume manufacture, belong to frequently examined stock materials in scientific and industrial laboratories. Because of a large number of freshly cut, dried or frozen plant samples requiring the determination of essential oil amount and composition, a fast, safe, simple, efficient and highly automatic sample preparation method is needed.Five sample preparation methods (steam distillation, extraction in the Soxhlet apparatus, supercritical fluid extraction, solid phase microextraction and pressurized liquid extraction) used for the isolation of aroma-active components from Thymus vulgaris L. are compared in the paper. The methods are mainly discussed with regard to the recovery of components which typically exist in essential oil isolated by steam distillation.According to the obtained data, PLE is the most efficient sample preparation method in determining the essential oil from the thyme herb. Although co-extraction of non-volatile ingredients is the main drawback of this method, it is characterized by the highest yield of essential oil components and the shortest extraction time required. Moreover, the relative peak amounts of essential components revealed by PLE are comparable with those obtained by steam distillation, which is recognized as standard sample preparation method for the analysis of essential oils in aromatic plants. 相似文献
80.
Ireneusz Sowa Roman Paduch Maciej Strzemski Sylwia Zielińska Ewelina Rydzik-Strzemska Jan Sawicki 《Natural product research》2018,32(5):605-609
The root of Symphytum officinale L. is commonly used in folk medicine to promote the wound healing, reduce the inflammation and in the treatment of broken bones. The objective of our investigation was to analyse the extract from S. officinale in term of its antioxidant activity and the effect on cell viability and proliferation of human skin fibroblast (HSF). Moreover, the quantification of main phenolics and allantoin was conducted using HPLC–DAD method. Five compounds were found: rosmarinic, p-hydroxybenzoic, caffeic, chlorogenic and p-coumaric acid. DPPH, FRAP and TPC assay showed the high antioxidant activity of the extract. MTT test proved the stimulatory effect on cell metabolism and viability of HSF cells. Moreover, no changes in cytoskeleton structure and cells shape were observed. The obtained results indicate that non-toxic extract from S. officinale root has strong antioxidant potential and a beneficial effect on human skin fibroblasts. 相似文献