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41.
Attila Lengyel Gyula Tolnai Zoltán Klencsár Vijayendra Kumar Garg Aderbal Carlos de Oliveira L. Herojit Singh Zoltán Homonnay Roland Szalay Péter Németh Bálint Szabolcs Mira Ristic Svetozar Music Ernő Kuzmann 《Journal of nanoparticle research》2018,20(5):137
57Fe Mössbauer spectroscopy, XRD, and TEM were used to investigate the effect of mandelic- and salicylic acid coatings on the iron oxide nanoparticles. These two carboxylic acids have similar molecules size and stoichiometry, but different structure and acidity. Significant differences were observed between the Mössbauer spectra of samples coated with mandelic acid and salicylic acid. These results indicate that the occurrence of iron microenvironments in the mandelic- and salicylic acid-coated iron oxide nanoparticles is different. The results can be interpreted in terms of the influence of the acidity of carboxylic acids on the formation, core/shell structure, and oxidation of coated iron oxide nanocomposites. 相似文献
42.
An analysis of the effect achieved by using a median filter for impulse noise rejection in a binary digital receiver, is carried out. Results have shown that the error probability can be considerably reduced in digital communication systems with a keying speed that is a few times less than is permitted by the channel bandwidth.<> 相似文献
43.
Recent studies of the growth rate of the different faces of potash alum crystals have revealed that these grow with variable growth rates. This phenomena can be considered on two time scales. In the long term “constant” growth remains for period of hours followed by growth arrests and so on. Superimposed on this are short term (minutes) fluctuations. The potential causes for these variations were discussed. 相似文献
44.
Steam distilled oil from the shoots, separated leaves, and stem, as well as from the flower of laurel (Laurus nobilis), grown in Montenegro, were analyzed by GC and GC/MS. The yield of essential oil was as follow: 1.4% in young shoots, 1.5%
in the separated leaves, and 0.7% in separated stems. The main constituents of all investigated oils were 1,8-cineole, methyleugenol,
and α-terpinyl acetate. Besides, α-pinene, β-pinene, sabinene, and linalool were also present. It was interesting and important for commercial samples of laurel essential
oil that there was no significant difference among the essential oil obtained from young shoots and those obtained from leaves
and stem. The main constituents of the flower oil were 1,8-cineole (15.7%), β-caryophyllene (9.5%), γ-muurolene (7.1%), α-terpinyl acetate (6.5%), and methyleugenol (3.9%).
Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 337–339, July–August, 2007. 相似文献
45.
The adsorption of Zn2+ ions on amorphous Fe(OH)3 and -Fe2O3, as a function of pH, has been investigated. In the pH region corresponding to the formation of positively charged Zn-hydroxy complexes, an abrupt increase in adsorption was observed. The influence of EDTA and glycine on the adsorption of Zn2+ by -Fe2O3 has also been investigated. Strong suppression of the adsorption of Zn2+ was observed for high [EDTA or Gly]/[Zn2+] concentration ratios. The results of the adsorption of Zn2+ in the presence of an organic ligand were explained by the formation of Zn-EDTA or Zn-glycine complexes and also by the occupation of adsorption sites by the free organic ligand. 相似文献
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47.
Synthesis and degradation profile of cast films of PPG-DMPA-IPDI aqueous polyurethane dispersions based on selective catalysts 总被引:1,自引:0,他引:1
Suzana M. Cakic Jakov V. Stamenkovic Dragan M. Djordjevic Ivan S. Ristic 《Polymer Degradation and Stability》2009,94(11):2015-2022
Waterborne polyurethane (WBU) dispersions synthesized from poly(propylene glycol) (PPG), dimethylolpropionic acid (DMPA), and isophorone diisocyanate (IPDI) with catalysts of different selectivity were prepared via by the conventional prepolymer isocyanate process. Two types of chain extenders were used, ethylene glycol (EG) and propylene glycol (PG), producing polyurethanes. The dispersions were neutralized by the addition of triethylamine. The thermal stability of the materials, obtained as cast films prepared from aqueous dispersions was evaluated by thermogravimetry (TG). It was observed that initial degradation temperatures were above 140 °C, with two-step degradation profiles. The use of a more selective catalyst in the formulations led to materials with higher thermal stability. DTG curves exhibited stages not perceptible in the curves of weight loss, which were mainly influenced by the differences in the formulations. Thermal decomposition of the obtained polyurethanes was followed by TG coupled with FTIR spectroscopy. 相似文献
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This Letter introduces a method for identifying geometrical models of interface evolution, directly from experimental imaging data. These local growth models relate normal growth velocity to curvature and its derivatives estimated along the growing interface. Such models can reproduce many qualitative features of dendritic crystal growth as well as predict quantitatively its early stages of evolution. Numerical simulations and experimental crystal growth data are used to demonstrate the applicability of this approach. 相似文献