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41.
Nikola Peřinka Markéta Držková Milena Hajná Bohumil Jašúrek Petra Šulcová Tomáš Syrový Marie Kaplanová Jaroslav Stejskal 《Journal of Thermal Analysis and Calorimetry》2014,116(2):589-595
The polyaniline dispersions stabilized with poly(N-vinylpyrrolidone) (PANI/PVP) were synthesized by oxidative polymerization with different mass ratios of PANI and PVP and different molar concentrations of the components in the polymerization mixture. The composite powders prepared from colloidal PANI/PVP dispersions were characterized by thermogravimetry and differential thermal analysis. The change in the ratio of PANI and PVP as well as the starting molar concentrations of aniline hydrochloride and oxidant has influence on the resulting properties of the dispersions. Concerning the doping, the results show that PANI/PVP powders are stable up to approximately 160 °C. Degradation of polymer chains starts at temperatures above 250 °C. The PANI/PVP composite powders with lower content of PANI exhibit slightly higher thermal stability. Further, colloidal PANI/PVP dispersions were screen-printed on aluminum foil for infrared spectroscopic characterization and on poly(ethylene terephthalate) foil for electrical measurements. The sheet resistance of printed layers measured by two-point probe was of the order of tens to thousands of kΩ sq?1. The influence of both the change in the composition and the drying temperature is discussed. 相似文献
42.
Hannu Teisala Mikko Tuominen Janne Haapanen Mikko Aromaa Milena Stepien Jyrki M. Mäkelä Jarkko J. Saarinen Martti Toivakka Jurkka Kuusipalo 《Cellulose (London, England)》2014,21(3):2033-2043
Surface wetting/anti-wetting and liquid absorption are relevant properties of many porous solids including paper and other cellulose-based materials. Here we demonstrate how surface wetting by water and water absorption of commercially available kraft paper can be altered by thin nanoparticle coatings fabricated by liquid flame spray in facile and continuous one-step process. Surface wettability and absorption properties of paper increased with silica and decreased with titania (TiO2) nanoparticle coatings. Moreover, the water-repellent (superhydrophobic) TiO2 nanoparticle coated paper could be switched to superhydrophilic and water absorbing by ultraviolet illumination. The experiments revealed that although surface wetting and liquid absorption of nanoparticle coated paper are strongly related to each other, they are two distinct phenomena which do not necessarily correlate. We propose wetting regimes on the nanoparticle coated paper samples on the basis of the experimental observations. 相似文献
43.
Maya M. Zaharieva Lyudmila L. Dimitrova Stanislav Philipov Ivanka Nikolova Neli Vilhelmova Petar Grozdanov Nadya Nikolova Milena Popova Vassya Bankova Spiro M. Konstantinov Dimitrina Zheleva-Dimitrova Hristo M. Najdenski 《Molecules (Basel, Switzerland)》2022,27(1)
This study evaluated the in vitro antineoplastic and antiviral potential and in vivo toxicity of twelve extracts with different polarity obtained from the herbaceous perennial plant Geum urbanum L. (Rosaceae). In vitro cytotoxicity was determined by ISO 10993-5/2009 on bladder cancer, (T-24 and BC-3C), liver carcinoma (HEP-G2) and normal embryonic kidney (HEK-293) cell lines. The antineoplastic activity was elucidated through assays of cell clonogenicity, apoptosis induction, nuclear factor kappa B p65 (NFκB p65) activation and total glutathione levels. Neutral red uptake study was applied for antiviral activity. The most promising G. urbanum extract was analyzed by UHPLC–HRMS. The acute in vivo toxicity analysis was carried out following OEDC 423. The ethyl acetate extract of aerial parts (EtOAc-AP) exhibited the strongest antineoplastic activity on bladder cancer cell lines (IC50 = 21.33–25.28 µg/mL) by inducing apoptosis and inhibiting NFκB p65 and cell clonogenicity. EtOAc and n-butanol extracts showed moderate antiviral activity against human adenovirus type 5 and human simplex virus type I. Seventy four secondary metabolites (gallic and ellagic acid derivatives, phenolic acids, flavonoids, etc.) were identified in EtOAc-AP by UHPLC–HRMS. This extract induced no signs of acute toxicity in liver and kidney specimens of H-albino mice in doses up to 210 mg/kg. In conclusion, our study contributes substantially to the detailed pharmacological characterization of G. urbanum, thus helping the development of health-promoting phytopreparations. 相似文献
44.
Charge transport and contact resistance in coplanar devices based on colloidal polyaniline dispersion
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Appan Merari Masillamani Nikola Peřinka Milena Hajná Jaroslav Stejskal Denis Tondelier Yvan Bonnassieux Jean‐Charles Vanel Bernard Geffroy Denis Mencaraglia 《Journal of Polymer Science.Polymer Physics》2016,54(17):1710-1716
The charge transport properties of thin films prepared from colloidal dispersion of polyaniline stabilized by poly(N‐vinylpyrrolidone) (PANI/PVP) have been investigated. The electrical characterization of coplanar device comprising of gold electrodes and PANI/PVP film deposited by spin coating served to gain insights into the contact and bulk resistance. The films prepared from PANI/PVP colloidal dispersion show high stability over a large temperature range. Temperature dependent measurements in the range from 90 to 350 K reveal that the charge transport can be described by a three‐dimensional variable‐range hopping mechanism as the dominant mode in the films. The stability of the films cast from dispersion within a large temperature range opens the possibility of the application as a polymer semiconductor layer in sensors and charge‐transport interlayer in organic solar cells. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1710–1716 相似文献
45.
Milena Simic Predrag Jovanovic Milos Petkovic Gordana Tasic Milos Jovanovic Vladimir Savic 《Journal of heterocyclic chemistry》2021,58(8):1665-1674
Octahydro-dipyrroloquinoline skeleton is the building component of a very few naturally occurring compounds. Nevertheless, these natural products have been attractive synthetic targets, and their study commanded development of efficient synthesis of this core. While the reported methods are based on the dimerization procedure of N-arylpyrrolidines of N-arylhomopropargyl amines, our approach relay on dipolar cycloaddition/amination sequence. This strategic approach allows sequential introduction of aromatic moieties increasing the product diversity and hence may be useful in further exploration of incargranine B or seneciobipyrrolidine derivatives. 相似文献
46.
Jean-Michel Morel Filippo Santambrogio 《Archive for Rational Mechanics and Analysis》2010,195(2):499-531
A branched structure is observable in draining and irrigation systems, in electric power supply systems, and in natural objects
like blood vessels, the river basins or the trees. Recent approaches of these networks derive their branched structure from
an energy functional whose essential feature is to favor wide routes. Given a flow s in a river, a road, a tube or a wire, the transportation cost per unit length is supposed in these models to be proportional
to s
α with 0 < α < 1. The aim of this paper is to prove the regularity of paths (rivers, branches,...) when the irrigated measure
is the Lebesgue density on a smooth open set and the irrigating measure is a single source. In that case we prove that all
branches of optimal irrigation trees satisfy an elliptic equation and that their curvature is a bounded measure. In consequence
all branching points in the network have a tangent cone made of a finite number of segments, and all other points have a tangent.
An explicit counterexample disproves these regularity properties for non-Lebesgue irrigated measures. 相似文献
47.
Lau Cher Hon Cervini Raoul Clarke Stephen R. Markovic Milena Ginic Matisons Janis G. Hawkins Stephen C. Huynh Chi P. Simon George P. 《Journal of nanoparticle research》2008,10(1):77-85
Nanosized powders of Ti-Nb oxide core-shell nanocrystals with atomic ratios of Nb/Ti = 0.11, 0.25, and 0.38 have been prepared
by two preparation routes. The first route was co-precipitation, followed by␣annealing, using NbCl5 as a source of Nb. The second route was coating of pure TiO2 nanocrystals by Nb-isopropoxide in liquid medium, followed by impregnation of the Nb into the nanoparticles by annealing.
Both methods yielded anatase nanocrystals with a Nb-rich shell and a core, which had much lower Nb loadings. The anatase structure
solid solution (with Nb incorporated) was stable under annealing up to 760°C. The particle size remained within the nanometric
scale (<50 nm) under heat-treatment up to 760°C. It has been shown that the fabricated powders can be redispersed in aqueous media
by simple ultrasound treatment, resulting in nanosized dispersions. Using a variety of analytical techniques, including depth
profiling of single nanocrystallites by AES combined with sputtering by Ar ions, the mechanism of the core-shell structure
creation was studied. It is proposed that the formation of the core-shell structure is governed by solubility limitations
in the co-precipitation route and by solubility and diffusion limitations in the coating-incorporation route. 相似文献
48.
Metal phosphorothioates are titrated in acetone, acetonitrile and dimethylformamide with potassium hydroxide, with potentiometric detection. They can be titrated in the presence of the corresponding phosphorothioic acids in the dimethylformamide. 相似文献
49.
Synthesis of 5-aryl[3,2-b]thieno-7-pyranones or thiopyranones and [3,2-b]thieno-9-chromenones from 3-methoxy or 3-thiomethoxy thiophenes is described, involving the use of pyridinium chlorhydrate as a cyclising and demethylating agent. 相似文献
50.
A method is proposed to identify gluon jets in the planar hadronic events recently found in e+e? annihilation. If a fast hadron is detected at a given angle θh ? 30° with respect to the axis opposite to the thrust axis, it is most probably a quark (or antiquark) fragment. An explicit formula then predicts the angle and energy of the unbiased accompanying gluon. 相似文献