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131.
Gordana Ćirić-Marjanović Ivanka Holclajtner-Antunović Slavko Mentus Danica Bajuk-Bogdanović Dragana Ješić Dragan Manojlović Snežana Trifunović Jaroslav Stejskal 《Synthetic Metals》2010,160(13-14):1463-1473
Polyaniline (PANI) micro/nanostructures were synthesized by the external-template-free oxidative polymerization of aniline in aqueous solution of 12-tungstophosphoric acid (WPA), using ammonium peroxydisulfate (APS) as an oxidant and starting the oxidation of aniline from slightly acidic media (pH 5.4–5.9). The effect of the initial weight ratio of WPA to aniline on molecular structure, morphology, and physicochemical properties of polyaniline 12-tungstophosphate (PANI-WPA) was investigated by FTIR, Raman and inductively coupled plasma optical emission (ICP-OES) spectroscopies, elemental analysis, X-ray powder diffraction (XRPD), scanning and transmission electron microscopies (SEM and TEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and conductivity measurements. The morphological change of polymerization products during a single polymerization process, from non-conducting submicro-/microspherical oligoaniline intermediates to semiconducting PANI-WPA consisted of self-assembled nanotubes and/or nanorods co-existing with submicro-/microspheres, has been revealed by SEM and TEM. The average diameter of nanorods in PANI-WPA samples decreased with increasing the initial WPA/aniline weight ratio. The incorporation of 12-tungstophosphate counter-ions into PANI matrix has been proved by FTIR, Raman and ICP-OES spectroscopies, TGA and DTA analysis. Electrical conductivity of PANI-WPA increased in the range (2.5–5.3) × 10?3 S cm?1 with the increase of the initial WPA/aniline weight ratio. The presence of branched structures and phenazine units besides the ordinary paramagnetic and diamagnetic emeraldine salt structural features in PANI-WPA was proved by FTIR and Raman spectroscopies. 相似文献
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133.
Richard Pokorný Pavel Hrma Seungmin Lee Jaroslav Klouzek Manoj K. Choudhary Albert A. Kruger 《Journal of the American Ceramic Society》2020,103(2):701-718
Development of mathematical models of heat and mass transfer in glass-melting furnaces began in the 1970s and progressed rapidly with advances in sophisticated experimental/numerical techniques and increasing computational power. Today, practically all newly built or rebuilt furnaces are optimized with these models to meet stringent quality requirements, reduce the unit costs of manufacturing, or control emissions. One remaining hurdle is to model the batch-to-glass conversion accurately enough to reliably assess the glass production rate. This article summarizes two key aspects of the batch-conversion modeling—the heat transfer and the kinetics of conversion—and reviews the current state-of-the-art approaches to simulating them. We critically examine the advantages of the commonly used heat transfer approach, but also explain that its predictive capabilities are significantly restricted by the dependence of batch thermal properties on the time-temperature history. We argue that kinetic approaches to the batch-conversion modeling would offer a significant improvement when coupled with the heat transfer approach. Finally, we summarize key areas requiring further research on the way toward a realistic model of the batch blanket. 相似文献
134.
135.
Lszl Ivanizs Ilaria Marcotuli Marianna Rakszegi Balzs Kalapos Kitti Szke-Pzsi Andrs Farkas Edina Türksi Eszter Gal Klaudia Kruppa Pter Kovcs va Dark va Szakcs Mahmoud Said Petr Cpal Jaroslav Doleel Agata Gadaleta Istvn Molnr 《International journal of molecular sciences》2022,23(7)
Grain dietary fiber content is an important health-promoting trait of bread wheat. A dominant dietary fiber component of wheat is the cell wall polysaccharide arabinoxylan and the goatgrass Aegilops biuncialis has high β-glucan content, which makes it an attractive gene source to develop wheat lines with modified fiber composition. In order to support introgression breeding, this work examined genetic variability in grain β-glucan, pentosan, and protein content in a collection of Ae. biuncialis. A large variation in grain protein and edible fiber content was revealed, reflecting the origin of Ae. biuncialis accessions from different eco-geographical habitats. Association analysis using DArTseq-derived SNPs identified 34 QTLs associated with β-glucan, pentosan, water-extractable pentosan, and protein content. Mapping the markers to draft chromosome assemblies of diploid progenitors of Ae. biuncialis underlined the role of genes on chromosomes 1Mb, 4Mb, and 5Mb in the formation of grain β-glucan content, while other QTLs on chromosome groups 3, 6, and 1 identified genes responsible for total- and water-extractable pentosan content. Functional annotation of the associated marker sequences identified fourteen genes, nine of which were identified in other monocots. The QTLs and genes identified in the present work are attractive targets for chromosome-mediated gene transfer to improve the health-promoting properties of wheat-derived foods. 相似文献
136.
Filtration paper was coated with a thin polyaniline film. The content of conducting polymer was 8.2 and 6.3 wt % for polyaniline hydrochloride and polyaniline base, respectively. After burning, the coated material retains the original fibrilar morphology of cellulose. The polyaniline coating converts to solid carbonaceous products. The resulting structure prevents the formation of gaseous carbon oxides by restricting the access of oxygen to cellulose. While the ash from the uncoated paper after burning is 0.005 wt %, the microtubular residue of polyaniline‐coated paper is 16–24 wt % of the original mass. The flame‐retardant performance of polyaniline and poly(1,4‐phenylenediamine) coatings was comparable both for the protonated forms and the corresponding bases. The conversion of polyaniline‐coated cellulose fibers to solid pyrolytic products was characterized by FTIR and Raman spectroscopies. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2347–2354, 2005 相似文献
137.
Jaroslav Cihlar Daniel Drdlik Zora Cihlarova Hynek Hadraba 《Journal of the European Ceramic Society》2013,33(10):1885-1892
The effects of acids (monochloroacetic, dichloracetic, trichloroacetic and sulfuric acids) and bases (diethanolamine, triethanolamine, piperidine) on electrophoretic mobility and electrophoretic deposition (EPD) of particles of amphoteric Al2O3 and ZrO2 in anhydrous 2-propanol were studied. It was found that the ζ-potential of Al2O3 and ZrO2 particles had in acidic and alkaline 2-propanol media opposite charge to that in aqueous medium. This phenomenon was explained by the low dissociation constants of acids and bases in 2-propanol. This enables electrosteric stabilization of Al2O3 and ZrO2 particles by acid anions and base cations. Similar electrophoretic behaviour of Al2O3 and ZrO2 particles in 2-propanolic dispersions stabilized by MCAA allowed the preparation of compact, regular layered laminates with high cohesion at the interface of layers. 相似文献
138.
Martin Michálek Katarína Bodišová Monika Michálková Jaroslav Sedláček Dušan Galusek 《Ceramics International》2013
Slip casting of stabilized aqueous suspensions followed by pressureless sintering was used for preparation of dense Al2O3/MWCNTs composites. The suspensions were stabilized by commercial polyelectrolyte dispersant Darvan C–N. In order to increase the stability, the pH value of the suspension was adjusted to ∼10. At this pH the highest ζ-potential values of the alumina powder and of the MWCNTs functionalised in boiling nitric acid were achieved. Two different agents, namely ammonium hydroxide and sodium hydroxide, were used for the pH adjustment. Their influence on the viscosity of suspensions and on consolidation and densification behaviour of the Al2O3/MWCNT composites was evaluated. The effect of ammonium hydroxide was more pronounced, as confirmed by lower viscosity of the suspension, higher sintered density, and fine-grained microstructure of the sintered composites. The Al2O3/t-MWCNTs composites with 0.1 wt% of the MWCNTs, with 99.9% relative density, the mean size of alumina grains ∼1 μm, and homogeneously distributed carbon nanotubes were prepared by the pressureless sintering at 1500 °C. 相似文献
139.
José Marcial Maria Rita Cicconi Carolyn I. Pearce Jaroslav Kloužek James J. Neeway Richard Pokorný Miroslava Vernerová John S. McCloy Emily T. Nienhuis Rolf Sjöblom Jamie L. Weaver Russell J. Hand Pavel Hrma Daniel R. Neuville Albert A. Kruger 《Journal of the American Ceramic Society》2023,106(3):1716-1731
There is wide industrial interest in developing robust models of long-term (>100 years) glass durability. Archeological glass analogs, glasses of similar composition, and alteration conditions to those being tested for durability can be used to evaluate and inform such models. Two such analog glasses from a 1500-year-old vitrified hillfort near Uppsala, Sweden have previously been identified as potential analogs for low concentration Fe-bearing aluminosilicate nuclear waste glasses. However, open questions remain regarding the melting environment from which these historic glasses were formed and the effect of these conditions on their chemical durability. A key factor to answering the previous melting and durability questions is the redox state of Fe in the starting and final materials. Past work has shown that the melting conditions of a glass-forming melt may influence the redox ratio value (Fe+3/∑Fe), a measure of a glass's redox state, and both melting conditions and the redox ratio may influence the glass alteration behavior. Synthetic analogs of the hillfort glasses have been produced using either fully oxidized or reduced Fe precursors to address this question. In this study, the melting behavior, glass transition temperature, oxidation state, network structure, and chemical durability of these synthesized glass analogs is presented. Resulting data suggests that the degree of network connectivity as impacted by the oxidation state of iron impacted the behavior of the glass-forming melt but in this case does not affect the chemical durability of the final glass. Glasses with a lower degree of melt connectivity were found to have a lower viscosity, resulting in a lower glass transition temperature and softening temperature, as well as in a lower temperature of foam onset and temperature of foam maximum. This lower degree of network connectivity most likely played a more significant role in accelerating the conversion of batch chemicals into glass than the presence of water vapor in the furnace's atmosphere. Future work will focus on using the results from this work with outcomes from other aspects of this project to evaluate long-term glass alteration models. 相似文献
140.
Patrycja Bober Jaroslav Stejskal Miroslava Trchová Jiřina Hromádková Jan Prokeš 《Reactive and Functional Polymers》2010,70(9):656-662
Two non-conducting chemicals, aniline and silver nitrate, dissolved in formic acid solutions, yielded a composite of two conducting products, polyaniline and silver. As the concentration of formic acid increased, an alternative reaction, the reduction of silver nitrate with formic acid to silver became dominant, and the content of silver in the composites increased. The formation of polyaniline was confirmed by UV–visible, FTIR, and Raman spectroscopies. The typical conductivity of composites was 43 S cm?1 at 84 wt.% of silver. Silver nanowires coated with polyaniline nanobrushes are produced at low concentrations of formic acid, the granular silver particles covered with polyaniline dominate at high acid concentrations. 相似文献