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排序方式: 共有192条查询结果,搜索用时 15 毫秒
111.
Miroslava Trchová Elena N. Konyushenko Jana Ková?ová 《Polymer Degradation and Stability》2009,94(6):929-938
Polyaniline (PANI) nanotubes were prepared by the oxidation of aniline in solutions of acetic or succinic acid, and subsequently carbonized in a nitrogen atmosphere during thermogravimetric analysis running up to 830 °C. The nanotubular morphology of PANI was preserved after carbonization. The molecular structure of the original PANI and of the carbonized products has been analyzed by FTIR and Raman spectroscopies. Carbonized PANI nanotubes contained about 8 wt.% of nitrogen. The molecular structure, thermal stability, and morphology of carbonized PANI nanotubes were compared with the properties of commercial multi-walled carbon nanotubes. 相似文献
112.
Polyaniline (PANI) nanotubes were prepared by oxidation of aniline in 0.4 M acetic acid. They were subsequently used as a
reductant of silver nitrate in 1 M nitric acid, water or 1 M ammonium hydroxide at various molar ratios of silver nitrate
to PANI. The resulting PANI-silver composites contained silver nanoparticles of 40–60 nm size along with macroscopic silver
flakes. Under these experimental conditions, silver was always produced outside the PANI nanotubes. Changes in the molecular
structure of PANI were analyzed by FTIR spectroscopy. Silver content in the composites was determined as a residue by thermogravimetric
analysis, and confirmed by density measurements. The highest conductivity of a composite, 68.5 S cm−1, was obtained at the nitrate to PANI molar ratio of 0.67 in water. Also, the best reaction yield was obtained in water. Reductions
performed in an acidic medium gave products with conductivity of 10−4–10−2 S cm−1, whereas the reaction in alkaline solution yielded non-conducting products. 相似文献
113.
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
114.
Jaroslav?StejskalEmail author Miroslava?Trchová Zuzana?Morávková Patrycja?Bober Michal?Bláha Ji?í?Pfleger Przemys?aw?Magdziarz Jan?Proke? Marek?Havlicek Niyazi?Serdar?Sariciftci Andreas?Sperlich Vladimir?Dyakonov Zoran?Zujovic 《Journal of Solid State Electrochemistry》2015,19(9):2653-2664
p-Phenylenediamine was oxidized with p-benzoquinone in the aqueous solutions of methanesulfonic acid (MSA). The conductivity of the products increased with increasing concentration of MSA from 1.5?×?10?12 S cm?1 in 0.1 M MSA up to 3.4?×?10?4 S cm?1 in 5 M MSA. The low-molecular-weight products are basically composed of one p-benzoquinone and two p-phenylenediamine molecules. Their molecular structure is discussed on the basis of mass, Fourier-transform infrared, Raman, NMR and electron paramagnetic resonance (EPR) spectroscopies. The formation of 2,5-di(p-phenylenediamine)-p-benzoquinone protonated with methanesulfonic acid best complies with the information provided by spectroscopic techniques. Its conversion to hydroquinone tautomer explains the formation of unpaired spins observed by EPR and their potential contribution to the conduction. 相似文献
115.
116.
Desislava I. Mantovska Miroslava K. Zhiponova Milen I. Georgiev Tsvetinka Grozdanova Dessislava Gerginova Kalina Alipieva Svetlana Simova Milena Popova Veneta M. Kapchina-Toteva Zhenya P. Yordanova 《Molecules (Basel, Switzerland)》2021,26(19)
Micropropagation of rare Veronica caucasica M. Bieb. was achieved by successful in vitro cultivation of mono-nodal segments on MS medium supplemented with 1.0 mg L–1 6-benzylaminopurine (BA) and then transferring the regenerated plants on hormone free basal MS medium for root development. In vitro multiplicated plants were successively acclimated in a growth chamber and a greenhouse with 92% survival. The number of plastid pigments and the total phenolics content in in vitro cultivated and ex vitro adapted plants were unchanged, and no accumulation of reactive oxygen species (ROS) was detected by staining with 3-3′-diaminobenzidine (DAB) and 2′,7′-dichlorofluorescein diacetate (DCF-DA). Nuclear Magnetic Resonance (NMR) fingerprinting allowed for the identification of the major alterations in metabolome of V. caucasica plants during the process of ex situ conservation. Iridoid glucosides such as verproside, aucubin and catalpol were characteristic for in vitro cultivated plants, while in ex vitro acclimated plants phenolic acid–protocatechuic acid and caffeic acid appeared dominant. The successful initiation of in vitro and ex vitro cultures is an alternative biotechnological approach for the preservation of V. caucasica and would allow for further studies of the biosynthetic potential of the species and the selection of lines with a high content of pharmaceutically valuable molecules and nutraceuticals. 相似文献
117.
118.
Broncová Gabriela Slaninová Tereza Trchová Miroslava 《Journal of Solid State Electrochemistry》2022,26(11):2423-2433
Journal of Solid State Electrochemistry - The characterization of electrochemically visualized latent fingerprints on steel surfaces is demonstrated. Optimization of electrochemical conditions of... 相似文献
119.
Martin tícha Tom Hloek Miroslava Bursov Radomír abala Ivan Jelínek 《Electrophoresis》2019,40(22):2936-2945
Riociguat is a novel antihypertensive drug for the treatment of pulmonary hypertension. We present electrophoretic characterization, i.e. migration behavior of riociguat and metabolite M1 as support for optimized CZE/MS assay. Fundamental separation parameters, such as peak width, symmetry, and resolution are studied in a series of ammonium formate buffers within pH range 2.60–5.61. The narrow region of peak symmetry lies close to pH 4.0 for both analytes. Accordingly, the value of resolution maximizes in a background electrolyte adjusted to pH 4.10. Basic calibration parameters estimated from CZE experiments with absorption photometric and mass spectrometric detection of riociguat and metabolite M1 were evaluated. More than three orders lower LOD was achieved with high resolution mass spectrometric detection. The observed difference in the sensitivity of both detection techniques gives priority to the utilization of CZE/MS in practice. The values of dissociation constants of riociguat and metabolite M1, pKBH, were determined from CZE measurements in lithium formate and lithium acetate background electrolytes with constant ionic strength. The value of pKBH = 4.30 ± 0.02 for riociguat corresponds well to the value already presented in the literature. According to our observation, metabolite M1 behaves like a slightly stronger base with estimated pKBH = 4.40 ± 0.02. 相似文献