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Kristýna Šebrlová Ondřej Peš Iva Slaninová Ondřej Vymazal Jana Kantorová Eva Táborská 《Chemical Papers》2015,69(5):698-708
Stylophorum lasiocarpum (Oliv.) Fedde (Papaveraceae) belongs to traditional Chinese medicine herbs but there was minimal information on the content of alkaloids in this plant. Extracts from the aerial part and roots were examined by liquid chromatography with UV and mass spectrometric detection, with nineteen alkaloids identified. Changes in alkaloid content over the entire vegetation period of a one- and two-year old plant were studied. The protoberberine alkaloids, coptisine and stylopine, were found to be the main substances in extracts of the aerial part irrespective of the plant’s age and time of harvest. Variable amounts of protopine, sanguinarine, chelerythrine, chelirubine, macarpine, chelilutine and berberine were also recorded in the aerial part. The roots contained significantly larger quantities of all alkaloids than the aerial part with the levels of most alkaloids varying from May to October, peaking in the middle of the vegetation period. Coptisine was the dominant alkaloid in all samples. The antiproliferative activities of the root extract and of seven individual alkaloids were tested on A375 human malignant melanoma cells. The significant dose-dependent toxicity of the root extract was attributed largely to the quaternary benzo[c]phenanthridine alkaloids, macarpine and sanguinarine. 相似文献
113.
Craig J. Kennedy Graeme J. Cameron Adriana Šturcová David C. Apperley Clemens Altaner Timothy J. Wess Michael C. Jarvis 《Cellulose (London, England)》2007,14(3):235-246
Cellulose isolated from celery collenchyma is typical of the low-crystallinity celluloses that can be isolated from primary
cell-walls of higher plants, except that it is oriented with high uniformity. The diameter of the microfibrils of celery collenchyma
cellulose was estimated by three separate approaches: 13C NMR measurement of the ratio of surface to interior chains; estimation of the dimensions of the crystalline lattice from
wide angle X-ray scattering (WAXS) measurements using the Scherrer equation; and the observation that microfibrils of this
form of cellulose have the unusual property of packing into an irregular array from which small angle X-ray scattering (SAXS)
shows features of both form and interference functions. The interference function contributing to the SAXS pattern implied
a mean microfibril centre-to-centre distance of 3.6 nm, providing an upper limit for the diameter. However modelling of the
scattering pattern from an irregular array of microfibrils showed that the observed scattering curve could be matched at a
range of diameters down to 2.4 nm, with the intervening space more or less sparsely occupied by hemicellulose chains. The
lateral extent of the crystalline lattice normal to the 200 plane was estimated as a minimum of 2.4 nm by WAXS through the
Scherrer equation, and a diameter of 2.6 nm was implied by the surface: volume ratio determined by 13C NMR. The WAXS and NMR measurements both depended on the assumption that the surface chains were positioned within an extension
of the crystalline lattice. The reliability of this assumption is uncertain. If the surface chains deviated from the lattice,
both the WAXS and the NMR data would imply larger microfibril diameters within the range consistent with the SAXS pattern.
The evidence presented is therefore all consistent with microfibril diameters from about 2.4 to 3.6 nm, larger than has previously
been suggested for primary-wall cellulose. Some degree of aggregation may have occurred during the isolation of the cellulose,
but the larger microfibril diameters within the range proposed are a consequence of the novel interpretation of the experimental
data from WAXS and NMR and are consistent with previously published data if these are similarly interpreted. 相似文献
114.
Petr Bělina Veronika Myšková Petra Šulcová 《Journal of Thermal Analysis and Calorimetry》2009,96(3):949-954
Two easy laboratory methods for preparation of rare-earth orthophosphates (crystallisation from phosphoric acid solution and
solid-state reaction with (NH4)2HPO4) were compared on the basis of the products’ properties with a focus on their application as new inorganic pigments. The
preparation method has a significant influence on optical properties. The samples prepared by crystallisation have lighter
and less rich colour and also change colour more under sunlight irradiation. The surface properties analysed by SEM and presence
of a greater amount of phosphoric acid in the crystallisation procedure influence the pH and resistivity of aqueous extract
of products and thus their corrosion-inhibition properties. The optical properties of rare-earth orthophosphates and their
preliminary corrosion tests show their potential application as highly efficient corrosion-inhibition pigments. 相似文献
115.
Josef Šlapal 《Aequationes Mathematicae》2018,92(1):75-90
We introduce and discuss a connectedness induced by n-ary relations (\(n>1\) an integer) on their underlying sets. In particular, we focus on certain n-ary relations with the induced connectedness allowing for a definition of digital Jordan curves. For every integer \(n>1\), we introduce one such n-ary relation on the digital plane \({\mathbb {Z}}^2\) and prove a digital analogue of the Jordan curve theorem for the induced connectedness. It follows that these n-ary relations may be used as convenient structures on the digital plane for the study of geometric properties of digital images. For \(n=2\), such a structure coincides with the (specialization order of the) Khalimsky topology and, for \(n>2\), it allows for a variety of Jordan curves richer than that provided by the Khalimsky topology. 相似文献
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MW ArF laser irradiation of gaseous cis-dichloroethene results in fast decomposition of this compound and in deposition of solid ultrafine Cl- and H-containing carbonaceous powder which is of interest due to its sub-microscopic structure and possible reactive modification of the C-Cl bonds. The product was characterized by electron microscopy, and FTIR and Raman spectra and it was revealed that HCl, H2, and C/H fragments are lost and graphitic features are adopted upon heating to 700°C. 相似文献
118.
Jaroslav Stejskal Irina Sapurina Miroslava Trchová Ivana Šeděnková Jana Kovářová Jitka Kopecká Jan Prokeš 《Chemical Papers》2015,69(10):1341-1349
Polypyrrole nanotubes were prepared by the oxidation of pyrrole with iron(III) chloride in a reaction mixture containing methyl orange. They were subsequently coated with polyaniline or poly(p-phenylenediamine) in situ during the oxidation of respective monomers in their presence. A part of the coaxial nanotubes was deprotonated using ammonia solution. The conductivity of polypyrrole nanotubes of 60 S cm?1, was reduced after the coating, and again after the deprotonation, but maintained at a level above 10?4 S cm?1. Infrared and Raman spectra reflect the presence of the polymer overlayer deposited on the polypyrrole template. Thermogravimetric analysis was used as a tool for the analytical carbonisation of samples in an inert nitrogen atmosphere. The conversion of conducting polymers to nitrogen-containing carbon nanotubes was confirmed using Raman spectra. 相似文献
119.
The influence of silica/titania and silica/zirconia nanoparticles on thermooxidative degradation of PMMA was studied by non-isothermal
thermogravimetry. Kinetic parameters describing the length of the oxidation induction periods were obtained from the treatment
of the dependence of oxidation onset temperature on heating rate. Using these parameters, the protection factors of nanoparticles
have been calculated. It was found that SiO2/TiO2 nanoparticles increase the thermooxidation stability of PMMA where the stabilizing effect, expressed as the protection factor,
depends on temperature only slightly. The stabilizing effect of SiO2/ZrO2 is much stronger than that of SiO2/TiO2 and decreases with increasing temperature. 相似文献
120.
The synthesis of new compounds based on Bi2O3 is investigated because they can be used as new ecological inorganic pigments. Chemical compounds of the (Bi2O3)1−x(Y2O3)x type were synthesized. The host lattice of these pigments is Bi2O3 that is doped by Y3+ ions. The incorporation of doped ions provides the interesting colours and contributes to a growth of the thermal stability
of these compounds. The simultaneous TG-DTA measurements were used for determination of the temperature region of the pigment
formation and thermal stability of pigments. This paper also contains the results of the pigment characterization by X-ray
powder diffraction and their colour properties. 相似文献