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21.
Pramod Bhatt S. M. Yusuf Ranu Bhatt G. Schütz 《Journal of Solid State Electrochemistry》2013,17(5):1285-1293
Crystalline films (thickness ~1 μm) of Prussian blue-based molecular magnets, synthesized using electrochemical method at two different reduction potentials ?0.5 and ?0.9 V, result into K0.1CrII 1.45[CrIII(CN)6]?·?mH2O (film 1) and K0.8CrII 1.1[CrIII(CN)6]?·?mH2O (film 2), respectively. The structural and magnetic properties of such films are investigated using atomic force microscopy (AFM), X-ray diffraction (XRD), infrared (IR) spectroscopy, and dc magnetization measurements. The film morphology, examined using AFM, shows uniformly distributed triangular crystallites over the substrate surface. The presence of CrIII–C≡N–CrII sequence, in the range of 1,900 to 2,300 cm?1 in IR spectra, confirms formation of Prussian blue analogues. The XRD results reveal information about the crystalline nature of the films and the relative intensities of the Bragg peaks change with the K+ ions. The exchange interaction between Cr ions through C≡N ligand confirms that the electron transfer from C≡N molecule to Cr ions is ferrimagnetic in nature. The high Curie temperatures (T C) are found to be ~195 and ~215 K for film 1 and film 2, respectively. The higher value of T C is attributed to the inclusion of more K+ ions for film 2, resulting decreases in the CrIII(C≡N)6 vacancies and increases in the number of nearest neighbors of CrII ions. The branching in the zero field-cooled and field-cooled magnetization data below Curie temperature is explained in terms of kinetic behavior of magnetic domains with different cooling conditions and the presence of water molecule vacancies in the lattice. 相似文献
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Siaka Yusuf Melinda Krahenbuhl Bryan Haskins Mike Hartman 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(1):23-26
To measure the gold content of a catalyst accurately, neutron activation analysis (NAA) is one of the methods of choice. NAA is preferred for such heterogeneous catalysts because: (1) it requires minimal sample preparation; (2) NAA provides consistent and accurate results; and (3) in most cases results are obtained much quicker than competing methods. NAA is also used as a referee for the other elemental techniques when results do not fall within expected statistical uncertainties. However, at very high gold concentrations, applying NAA to determine the gold in a heterogeneous catalyst is more challenging than a routine NAA procedure. On the one hand, the neutron absorption cross section for gold is very high, resulting in significant self-shielding related errors. On the other hand, gold exhibits low energy resonance neutron absorptions. In this application the self-shielding minimization effort was handled more rigorously than the classic suppression of neutron flux within a specimen. This non-routine approach was used because: (1) for most applications, high accuracy, <3 % relative, is desired, (2) the low energy resonances of gold make its neutron reaction rate complex and (3) the TRIGA reactor flux profile used in this study contains both thermal and significant epithermal neutron fluxes. Accuracy and precision, using this new approach, are expected to improve from 15 % to better than 3 % relative uncertainty. This has been accomplished through a rigorous assessment of the observed effects of low energy resonance on the neutron flux spectral shape within the sample and designing an experiment to minimize the effects. 相似文献
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Farnaz Farbod Behzad Pourabbas Mehdi Sharif 《Journal of Polymer Science.Polymer Physics》2013,51(6):441-451
Breath figure formation was carried out directly on the surface of poly(methylmethacrylate) using a mixture of a good solvent, tetrahydrofuran, and a nonsolvent, water. Direct breath figure formation was coined for this method and a mechanism was proposed to describe the figure formation by the method based on hypothesizes available for the normal breath figure formation. The proposed mechanism is such that the sonication effect, immersion time, and water content on characteristics of the obtained figures can be explained. The figured surface was then made superhydrophobic with a water contact angle of 175° using in situ growing of perfluoro modified silica nanoparticles inside the figure cell by one-pot method. The spherical modified silica nanoparticles were detected being trapped by figure features providing a mechanical entrapment of the low-surface energy nanoparticles. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013 相似文献
25.
Ozge Malay Iskender Yilgor Yusuf Z. Menceloglu 《Journal of Sol-Gel Science and Technology》2013,67(2):351-361
In-situ liquid-state 29Si nuclear magnetic resonance was used to investigate the temporal concentration changes during ammonia-catalyzed initial hydrolysis of tetraethyl orthosilicate in different solvents (methanol, ethanol, n-propanol, iso-propanol and n-butanol). Dynamic light scattering was employed to monitor simultaneous changes in the average diameter of silica particles and atomic force microscopy was used to image the particles within this time frame. Solvent effects on initial hydrolysis kinetics, size and polydispersity of silica particles were discussed in terms of polarity and hydrogen-bonding characteristics of the solvents. Initial hydrolysis rate and average particle size increased with molecular weight of the primary alcohols. In comparison, lower hydrolysis rate and larger particle size were obtained in the secondary alcohol. Exceptionally, reactions in methanol exhibited the highest hydrolysis rate and the smallest particle size. Ultimately, our investigation elaborated, and hence confirmed, the influences of chemical structure and nature of the solvent on the formation and growth of the silica particles under applied conditions. 相似文献
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Journal of Cluster Science - In this research, we used a fast and simple method for synthesis of calcium titanate (CaTiO3) and calcium ferrite (CaFe2O4) nanostructures: microwave assisted... 相似文献
27.
The present research work describes the productive synthesis of novel bisbenzopyronopyran derivatives 4(a-h) and 5(a-h) via the photocyclization reactions of bischromones 3(a-h) under the inert conditions. The latter compounds have been realized efficiently through the O-alkylation reactions of the 3-hydroxychromone 2 with suitable dihalogenated aliphatic/aromatic/heteroaromatic reagents in the presence of dry acetone/anhydrous K2CO3/Bu4N+I− (PTC). The cyclization reaction of chalcone 1 under the Algar-Flynn-Oyamada reaction conditions (KOH/H2O2) could results in the formation of compound 2 in the good yield. The structural scaffolds of the newly prepared bischromones and resultant bisbenzopyronopyrans have been certified from the meticulous analysis of their various spectroscopic parameters such as UV-Vis, IR, 1H/13C-NMR, and ESI-MS. It was found that o/m/p-xylene and pyridine-linked final symmetrical bistetracycles exhibited higher antimicrobial potencies as compared to alkyl chain-linked cyclized products. The bischromones 3(a-h) could be able to endow modest level of antimicrobial behavior. 相似文献
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Akbas Yusuf Azmi Yusan Sabriye 《Journal of Radioanalytical and Nuclear Chemistry》2020,323(2):763-772
Journal of Radioanalytical and Nuclear Chemistry - In this study, low-cost olive pomace, which is a waste of olive mill, was chemically modified using different acids, characterized, and utilized... 相似文献
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