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1.
Redl FX Black CT Papaefthymiou GC Sandstrom RL Yin M Zeng H Murray CB O'Brien SP 《Journal of the American Chemical Society》2004,126(44):14583-14599
We have investigated the structural, magnetic, and electronic properties of nonstoichiometric iron oxide nanocrystals prepared by decomposition of iron(II) and iron(0) precursors in the presence of organic solvents and capping groups. The highly uniform, crystalline, and monodisperse nanocrystals that were produced enabled a full structural and compositional survey by electron microscopy and X-ray diffraction. The complex and metastable behavior of nonstoichiometric iron oxide (wüstite) at the nanoscale was studied by a combination of Mossbauer spectroscopy and magnetic characterization. Deposition from hydrocarbon solvents with subsequent self-assembly of iron oxide nanocrystals into superlattices allowed the preparation of continuous thin films suitable for electronic transport measurements. 相似文献
2.
Amale Nezzal Luc Aerts Marleen Verspaille Geert Henderickx Andreas Redl 《Journal of Crystal Growth》2009,311(15):3863-3870
The polymorphism of sorbitol was investigated, confirming the existence of four anhydrous crystalline phases plus the hydrate. The crystallised melt (CM), the alpha form, and the gamma form were obtained via a dry route. The CM was confirmed to be a crystalline state with a spherulite morphology. The alpha form was obtained via direct conversion from the CM, in contrast to more complicated routes previously reported, and was found to have a very high crystallinity. Gamma crystals were obtained by seeding the melt at high temperature; however, crystallinity was clearly less than for alpha crystals. 相似文献
3.
Let \((X_n :n\in \mathbb {Z})\) be a two-sided recurrent Markov chain with fixed initial state \(X_0\) and let \(\nu \) be a probability measure on its state space. We give a necessary and sufficient criterion for the existence of a non-randomized time T such that \((X_{T+n} :n\in \mathbb {Z})\) has the law of the same Markov chain with initial distribution \(\nu \). In the case when our criterion is satisfied we give an explicit solution, which is also a stopping time, and study its moment properties. We show that this solution minimizes the expectation of \(\psi (T)\) in the class of all non-negative solutions, simultaneously for all non-negative concave functions \(\psi \). 相似文献
4.
G Baier G Wollensak E Mur B Redl G St?ffler W G?ttinger 《Journal of chromatography. A》1990,525(2):319-328
A comparison of the efficiencies of hydrophobic interaction chromatography, ion-exchange chromatography, reversed-phase chromatography and gel permeation chromatography in the separation of tear proteins was made using a variety of different buffers. Separation of immunoglobulins, lactoferrin, albumin, PMFA (protein migrating faster than albumin) and lysozyme was accomplished by gel permeation chromatography in less than 30 min using a TSK-type SW3000 column equilibrated with ammonium acetate buffer (pH 4.1) with a high reproducibility. When gel permeation chromatography was used as a completely automated diagnostic method, only minute volumes (1.0 microliter) of tear samples were necessary for the quantitative analysis of proteins. The other three methods proved to be more suitable for the preparation of individual tear proteins but were less suitable for their quantitation. 相似文献
5.
Andréas Redl Marie Hélène Morel Joëlle Bonicel Stéphane Guilbert Bruno Vergnes 《Rheologica Acta》1999,38(4):311-320
The rheological behaviour of a gluten plasticized with glycerol has been studied in oscillatory shear. The mixing operation
in a Haake batch mixer leads to a maximum torque for a level of specific energy (500–600 kJ/kg) and temperature (50–60 °C)
quite independent of mixing conditions (rotor speed, mixing time, filling ratio). The gluten/glycerol dough behaves as a classical
gluten/water dough, with a storage modulus higher than the loss modulus over the frequency range under study. A temperature
increase induces a decrease of moduli, but the material is not thermorheologically simple. Glycerol has a plasticizing effect,
which can be classically described by an exponential dependence. Mixing conditions influence the viscoelastic properties of
the material, mainly through the specific mechanical energy input (to 2000 kJ/kg) and temperature increase (to 80 °C). Above
50 °C, specific mechanical energy highly increases the complex modulus. The aggregation of proteins, as evidenced by size-exclusion
chromatography measurements, occurs later as the dough temperature reaches 70 °C. The nature of network interactions and the
respective influence of hydrophobic and disulphide contribution is discussed. A general expression is proposed for describing
the viscous behaviour of a gluten/glycerol mix, which could seem simplistic for such a complex rheological behaviour, but
would remain sufficient for modelling the flow behaviour in a twin screw extruder.
Received: 24 November 1997 Accepted: 28 April 1999 相似文献
6.
Sandra Domenek Marie-Hélène Morel Andreas Redl Stéphane Guilbert 《Macromolecular Symposia》2003,197(1):181-192
Structural investigation of gluten-glycerol blends subjected to heat-treatment was carried out by size-exclusion high performance liquid chromatography (SEC) and stress-strain tests. SEC is a valuable tool to investigate the size distribution of gluten protein chains, while the molecular weight between network junctions (Me) can be estimated from the elastic plateau modulus. Wheat gluten aggregation upon thermosetting seems to proceed through direct covalent cross-linking between glutenin oligomers and the gluten macropolymer. The time course of the reaction, which showed a slow-down of the reaction rate with time, was described by a simple mechanistic model. The deceleration of the reaction rate was presumably due to the development of a three-dimensional protein network, which decreased the accessibility of reactive groups. The network formation could be evidenced separately by the decrease of Me during the heat-treatment. 相似文献
7.
G. C. Papaefthymiou F. X. Redl C. T. Black R. L. Sandstrom M. Yin C. B. Murray S. P. O’Brien 《Hyperfine Interactions》2005,165(1-4):239-245
We present Mössbauer studies of hybrid iron-oxide nanoparticles obtained by the disproportionation of oleic acid stabilized wüstite (FexO) nanoparticles produced by selective oxidation of iron pentacarbonyl in high boiling temperature organic solvents. The results support X-ray diffraction and Transmission Electron Microscope studies of the presence of mixed FexO and Fe3O4 phases within the nanoparticles whose relative content can be altered through heat treatment in nitrogen atmosphere. Furthermore, the Mössbauer study gives evidence of the presence of an amorphous, spin-glass like phase due to spin frustration at the FexO/Fe3O4 interface. 相似文献
8.
Abhay Markande Amale Nezzal John Fitzpatrick Luc Aerts Andreas Redl 《Journal of Crystal Growth》2012,353(1):145-151
The effects of impurities on dextrose monohydrate crystallization were investigated. Crystal nucleation and growth kinetics in the presence of impurities were studied using an in-line focused beam reflectance monitoring (FBRM) technique and an in-line process refractometer. Experimental data were obtained from runs carried out at different impurity levels between 4 and 11 wt% in the high dextrose equivalent (DE) syrup. It was found that impurities have no significant influence on the solubility of dextrose in water. However, impurities have a clear influence on the nucleation and growth kinetics of dextrose monohydrate crystallization. Nucleation and growth rate were favored by low levels of impurities in the syrup. 相似文献
9.
Around 100 porphyrin units have been selectively linked at C(6)-O to a cellulose (Avicel). The properties of the metal-free and zincated porphyrin-celluloses 2 and Zn-2 have been determined by optical and electrochemical methods. Circular dichroism indicates a helical arrangement of the porphyrin units and reveals intra-chain coupling reminiscent, in the broadest sense, of strands of nucleic acids. Cyclic voltammetry and spectroelectrochemistry have been used to characterize the radical ions and dianions. The electrochromism of the oxidation of cellulose 2 to porphyrin radical cations of 2 has been employed for both molecular switching and the transduction of an electrochemical input into chiroptical signal expression. 相似文献
10.
Sandra Domenek Marie-Hélène Morel Andreas Redl Steéphane Guilbert 《Macromolecular Symposia》2003,200(1):137-146
Wheat gluten samples were subjected to different thermo-mechanical treatments. Kinetics of protein aggregation and changes in network structure were investigated through biochemical and rheological measurements. Temperature induced protein aggregation through disulphide cross-links. Shear treatment alters the aggregation mechanism since a lower energy of activation was observed. Accumulation of aggregated protein enhances the elastic behaviour of the material. The strong correlation found between the extent of protein aggregation and the molecular weight between cross-links reveals the important role of covalent bonds in the network connectivity. 相似文献