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991.
M. Prekajski Z. Dohčević-Mitrović M. Radović B. Babić J. Pantić A. Kremenović B. Matović 《Journal of the European Ceramic Society》2012,32(9):1983-1987
Nanocrystalline powders of solid solution CeO2–Bi2O3 were synthesized by self-propagating room temperature reaction (SPRT) procedure with composition (Ce1?xBixO2?δ where the x = 0.1–0.5). X-ray diffraction analyses show that for x < 0.50 a solid solution with fluorite structure is formed. Rietveld's structure refinement method was applied to characterize prepared powders and its microstructure (size–strain). The lattice parameters increase according to Vegard's rule with increasing of Bi concentration. The average crystallite size is about 2–3 nm. Spectroscopic ellipsometry and Raman scattering measurements were used to characterize the samples at room temperature. The Raman measurements demonstrated electron molecular vibrational coupling and increase of oxygen vacancy concentration whereas increase of Bi content provokes a small decrease of optical absorption edge in comparison with pure ceria. Specific surface area of obtained powders was measured by Brunauer–Emmet–Teller (BET) method. 相似文献
992.
František Lofaj Milan Ferdinandy Gregorz Cempura Ján Dusza 《Journal of the European Ceramic Society》2012,32(9):2043-2051
Instrumented indentation, AFM (atomic force microscopy) and tribological studies were performed on PE CVD (Plasma Enhanced Chemical Vapor Deposition) nanocomposite WC–C coatings to investigate the effects of surface roughness on the reliability of nanoindentation data and the possibilities of different AFM modes in nanomechanical testing, which can be used as a feedback to optimize deposition technology from the viewpoint of their mechanical properties. It was confirmed that surface roughness below 30 nm is necessary to keep the scatter of indentation modulus, EIT, and hardness, HIT, below 15%. PF QNM (Peak Force Quantitative NanoMechanical) mode was successfully applied for qualitative mapping of the elastic modulus of coatings with the stiffness above 300 GPa. LFM (lateral force microscopy) mode showed only weak contrast and quantitative measurements in both AFM modes require precise calibration. Coefficients of friction of the studied WC–C coatings were below 0.2 at RT, but increased to 0.7–0.8 at 450 °C due to the formation of a transfer film. Optimization of the deposition conditions based on nanoindentation resulted in the increase of EIT from ~220 GPa to 350 GPa and HIT from ~17 GPa to ~29 GPa. 相似文献
993.
Božidar P. M. Ćurčić Slobodan E. Makarov Vele V. Tešević Milka B. Jadranin Ljubodrag V. Vujisić 《Journal of chemical ecology》2009,35(8):893-895
Defensive secretions of the callipodidan species Apfelbeckia insculpta contain a p-cresol as the main component and phenol in traces. This is the first identification of these compounds in a European callipodidan
species. The repugnatory glands of A. insculpta are of the spirobolid type and consist of a spherical reservoir, a simple duct, and a valvular cuticular infolding that opens
onto the lateral surface of the millipede via a pore. 相似文献
994.
Dichlorofluorescein derivatives with two aza-crown ether binding units were prepared by the Mannich reaction and their chemosensing behaviors toward transition metal ions were investigated. An 18-crown-6 ether derivative exhibited pronounced Cu2+-selective fluorescence signaling, with selectivity over other common physiologically important alkali, alkaline earth and transition metal ions. The compound also displayed 1:1 complex formation with Cu2+ ion, with a detection limit of 2.9 × 10?6 M in an aqueous 50% DMSO solution at pH 7, showing that it may offer potential as a chemosensor for the detection of submillimolar Cu2+ ions in physiological environments. A 15-Crown-5 ether analogue also revealed selective Cu2+ signaling, although with somewhat diminished selectivity compared with its 18-crown-6 counterpart. 相似文献
995.
996.
By means of the modification of Medve?’s de-singular method and a result of two-dimensional linear integral inequalities, components-wise (not on some norm) upper bounds are obtained for solutions of a class of nonlinear two-dimensional systems of fractional differential equations. The uniqueness and continuous dependence of the solutions are also discussed here. 相似文献
997.
This paper deals with a viscoelastic model of the hamstring muscle group. The model includes fractional derivatives of stretching force and elongation, as well as restrictions on the coefficients that follow from the Clausius–Duhem inequality. On the basis of a ramp-and-hold type of experiment, four rheological parameters have been calculated by numerical treatment ab initio. Riemann–Liouville fractional derivatives were approximated numerically using the Grünwald–Letnikov definition. Obtained results were verified by use of the Laplace transform method. The stretching force in time domain involves Mittag-Leffler-type function. 相似文献
998.
This paper deals with the environmental bill of material and technology routing: evaluating components and process impacts
on the environmental strategy map through an integrated LCA approach. It introduces these two new elements in the definition
of new approaches to complement environmental and financial considerations into a single sustainability indicator. The basic
idea presented is that each component of a specific product has a certain environmental burden and consequently contributes
to the environmental footprints. Those contributions are identified as environmental performance points (EPP). When an item
is routed through different technology processes to build the final product, it keeps contributing to the overall environmental
burden. These contributions are again identified as EPP. The sum of all EPPs, categorized by footprints, provides the basis
for creation of the characteristic environmental performance strategy map, previously developed by the authors of this paper.
This new approach allows wide flexibility: the impact of changing a component, material or a production process will be reflected
immediately on the map. 相似文献
999.
Z. Grubač M. Metikoš-Huković R. Babić I. Škugor Rončević M. Petravić R. Peter 《Materials science & engineering. C, Materials for biological applications》2013,33(4):2152-2158
Mg and Mg-alloys are promising materials for biodegradable implants. In order to slowdown the Mg-alloy (AZ91D) degradation and enhance its biocompatibility, the alloy surface was modified with alkylphosphonate self-assembling films. The binding configuration and the structural organization of alkylphosphonate monolayers on the Mg-alloy surface were investigated using contact angle measurements, FTIR, and XPS. Combination of FTIR and XPS data indicated the presence of several different bonding modes (mono-, di-, and tri dentate) of phosphonate head groups with the alloy surface. The existence of well organized and ordered self-assembled alkylphosphonate monolayers with good barrier protecting properties in a physiological solution is a key step in the development of biocompatible Mg-alloy implants. 相似文献
1000.