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1.
Allais C. Keller G. Lesieur P Ollivon M. Artzner F. 《Journal of Thermal Analysis and Calorimetry》2003,74(3):723-728
Polymorphism of trilaurin mixed with 4% of cholesterol was studied with a setup coupling calorimetry and phase characterisation
by in-situ X-ray diffraction (Microcalix). Four polymorphic forms were identified. Monotropic and enantiotropic transitions
were identified from the reconstruction of Gibbs free energy diagram which allows the control of trilaurin polymorphism.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
L. Forte K. Andrieux G. Keller C. Grabielle-Madelmont S. Lesieur M. Paternostre M. Ollivon C. Bourgaux P. Lesieur 《Journal of Thermal Analysis and Calorimetry》1998,51(3):773-782
The thermotropic transitions of 1,2-dipalmitoylphosphatidylcholine (DPPC) and the structural changes of its lamellar phases have been studied between 0 and 50°C by both DSC and synchrotron small angle X-ray diffraction/scattering as a function of temperature (XRDT) and sodium taurocholate concentration [TC] in the 0–40 mM range ([DPPC]=50 mM) at pH 7.4. The existence of multiple phase transitions (up to 5 peaks within a 5°C interval) in a narrow domain of temperature between 25 and 42°C depending on the [TC]/[lipid] ratio was observed in the DSC curves. XRDT showed that at low ratios they might correspond to transitions between lamellar phases, the structural characteristics of which are given. At higher ratios a lamellar to micellar transition was observed, and the temperature at which it was observed decreased as a function of the TC content. The relationships with DPPC vesicle bilayer permeabilization and solubilization are discussed. 相似文献
3.
G. Keller F. Lavigne L. Forte K. Andrieux M. Dahim C. Loisel M. Ollivon C. Bourgaux P. Lesieur 《Journal of Thermal Analysis and Calorimetry》1998,51(3):783-791
A new technique, that allows simultaneous time-resolved synchrotron X-ray diffraction as a function of temperature (XRDT) and high sensitivity DSC to be carried out in the same apparatus, has been developed. Microcalorimetry and XRDT scans can be performed at any rate between 0.01 and 10°C min?1 with a 0.01°C temperature resolution in the temperature range, 30–130°C and at lower cooling rates but the same heating rates in the ?30–+30°C range. The use of a single and very small sample (1 to 20 μl) contained in a thin glass capillary for both measurements and simultaneous data collection prevents any temperature shift between recordings and any possible difference in the thermal histories of the samples. 相似文献
4.
G. Keller F. Lavigne C. Loisel M. Ollivon C. Bourgaux 《Journal of Thermal Analysis and Calorimetry》1996,47(5):1545-1565
The thermal behavior of three ural fats (displaying very different composition), cocoa butter (CB)2, lard, and a stearin obtained from anhydrous milk-fat (AMF) fractionation, were studied by both DSC and X-ray diffraction as a function of temperature (XRDT). To perform temperature explorations between –30C and +80C, at rates identical to those used for DSC and ranging from 0.1 K min–1 to 10 K min–1, a new set of X-ray sample-holders, temperature-controlled by Peltier effect, has been developed. It is shown that the three more stable polymorphic forms of CB were easily characterized by either X-ray diffraction or DSC, and existence of two -3L forms was confirmed. On the contrary, the more complex polymorphism of lard and AMF required combined examination by DSC and XRDT and the brightness of the synchrotron source for studies at the highest heating rates. Quantitative analysis of the long spacings of XRDT recordings is invaluable for interpretation of thermal events. For instance, it was found that the simultaneous formation of two polymorphic forms, of apparent long spacing of 34 and 42 å, at the onset of lard crystallization might explain the difficulty of its fractionation.Special thanks to Courtney P. Mudd (NIH, Bethesda) for his pertinent advice on the mounting and use of thermoelectric devices. The study of lard crystallization was initiated by Valerie Portalier and suggested by Jean-Luc Vendeuvre of CTSCCV (Maisons-Alfort). For the AMF part of this study, stearin was fractionated by ADRIA Normandie, while characterization of its thermal properties was performed as part of a research program funded by ARILAIT Recherches and the French Ministry of Research and Technology. 相似文献
5.
M. Ollivon G. Keller C. Bourgaux D. Kalnin P. Villeneuve P. Lesieur 《Journal of Thermal Analysis and Calorimetry》2006,85(1):219-224
Adaptive or smart hybrid
composites consisting of a polymer matrix reinforced by aramid fibres and
incorporating pre-strained Shape Memory Alloy (SMA) wires are able to tune
some of their properties, such as their shape, the natural vibration frequency
or the damping coefficient, in response to an external stimulus. The functional
properties of these systems are directly related to the reversible martensitic
transformation in the SMA elements. In this work the transformational behaviour
of both free SMA wires and SMA wires embedded in polymer matrix is investigated
by means of DSC. The martensitic transformation of the constrained wires is
impeded by the polymer matrix, while the interface integrity plays a crucial
role. 相似文献
6.
Angelova A Angelov B Papahadjopoulos-Sternberg B Ollivon M Bourgaux C 《Langmuir : the ACS journal of surfaces and colloids》2005,21(9):4138-4143
Proteocubosomes are nanostructured open-nanochannel hierarchical fluid vehicles characterized by a cubic lattice periodicity of the lipid/protein supramolecular assembly (protein-loaded cubosomes). They are obtained here at very high hydration levels by a three-dimensional (3D) self-assembly process, which exploits a protein-directed 3D patterning and fragmentation to create a new, tertiary-level structural order of fluid lipid/water interfaces. Our freeze-fracture electron microscopy study reveals that the proteocubosome structures are built up by patterned assemblies of nanocubosomes, which comprise 3D nanoporous fracture surfaces throughout. Complex cubosomic architectures, involving arrays of nanodroplets (larger than 20 nm) inside the proteocubosome particles, are established at high resolution. The soft-matter hierarchical nanocompartment formations display internal aqueous pores belonging to the D-type lipid cubic lattice nanochannel system that is proven by synchrotron X-ray diffraction. The reported nanostructured fluid may give rise to novel applications in nanofluidic biomimetic devices, porous protein drug delivery vehicles, nanoscale enzymatic bioreactors, and protein-encapsulating fluid nanomaterials. 相似文献
7.
Perrine Pivette Vincent Faivre Georges Daste Michel Ollivon Sylviane Lesieur 《Journal of Thermal Analysis and Calorimetry》2009,98(1):47-55
Two lipid binders, glyceryl behenate and paraffin wax, were examined regarding their ability to be used in a prilling process.
Prilling has the advantage to produce microgranules very reproducible in size and shape but involves ultrafast cooling of
liquid droplets. The different steps to produce solid micropheres from the molten state were successfully modelled to predict
crystallisation time as a function of the binder used. Bulk versus microgranules characterization by differential scanning
calorimetry, X-ray diffraction and microscopies showed the peculiar suitability of the 50/50 mixture of the two lipid binders
for prilling, in agreement with the theoretical approach. 相似文献
8.
L. Komunjer M. Ollivon B. Fouconnier A-T Luong I. Pezron D. Clausse 《Journal of Thermal Analysis and Calorimetry》2009,98(1):125-131
Trichlorofluoromethane (CCl3F) and water form clathrate hydrate which melts at 8.5 °C under atmospheric pressure. By DSC and X rays analysis we could
distinguish between hydrate and ice formed in emulsion containing NaCl and show that quantity of hydrate formed and its dissociation
temperature are dependent on solution concentration. The equilibrium curve hydrate-NaCl solution is displaced towards higher
temperatures with respect to corresponding ice curve. Consequently solid–liquid equilibrium can not be established in presence
of both solids. Growth of hydrate crystals at the expense of ice was evidenced. Role of salt in hydrate growth and ice melting
is examined. 相似文献
9.
Lopez C Bourgaux C Lesieur P Bernadou S Keller G Ollivon M 《Journal of colloid and interface science》2002,254(1):64-78
Crystallization of triacylglycerols (TG) within milk fat globules of creams is studied with an instrument coupling time-resolved synchrotron X-ray diffraction (XRDT) at both small and wide angles and high-sensitivity differential scanning calorimetry (DSC) at cooling rates of -3 and -1 degrees C/min from 60 to -10 degrees C and compared to that of the anhydrous milk fat (AMF). Simultaneous thermal analysis permits correlation of the formation of the different crystalline species monitored by XRDT to the DSC events. Under the above cooling conditions, milk fat TG sequentially crystallize, within the globules, from about 19 degrees C, in three different lamellar structures with double-chain length (2L) stackings of 47 and 42 A and a triple-chain length (3L) stacking of 71 A, all of alpha type, which are correlated to two or three overlapped exothermic peaks recorded by DSC. Compared to what is observed for AMF, TG crystallization in emulsion (i) favors sub-alpha formation at low temperature and (ii) induces layer stacking defects in 3L crystals. Subsequent heating at 2 degrees C/min shows numerous structural rearrangements before final melting, confirming that (i) cooling at -1 degrees C/min leads to the formation of unstable crystalline varieties in the dispersed state and (ii) a monotropic transition alpha-->beta' takes place. Similar behavior is observed for cooling at -3 degrees C/min and subsequent heating. An overall comparison of the thermal and structural properties of the crystalline species formed as a function of the cooling rate, between >1000 and 0.15 degrees C/min, and stabilization time at 4 degrees C is given. Depending on the cooling rate, at least five crystalline subcell species are observed at wide angles, alpha and sub-alpha, two beta' and one beta. At small angles, at least six lamellar stackings are identified, three 3L and three 2L. However, a single subcell packing (e.g., alpha) might correspond to several longitudinal chain stackings, demonstrating the usefulness of the small-angle XRD technique. Reconstituted emulsions homogenized under different pressures are used to determine the influence of droplet size on crystallization. The decrease of droplet size induces (i) a higher supercooling/supersaturation and (ii) a higher disorder and/or a smaller size of TG crystals within the emulsion droplets. At the supramolecular scale, polarized light microscopy shows that various cooling rates applied in situ using a temperature-controlled stage directly influence crystal sizes and their type of organization within milk fat globules. The faster the cooling rate, the smaller the size of the crystals within the globules. 相似文献
10.
The enthalpies and entropies of fusion of unstable α and β' forms of saturated even monoacid triglycerides are determined by direct and indirect calorimetric methods. The choice of these two methods is discussed. The enthalpies and entropies are compared to those of the stable β form, conventionally measured by calorimetry. Linear laws of the type y=an+b are deduced for each form in order to relate these data to n, the carbon number of acyl chains. The significance of the a and b parameters is discussed. A comparison with the corresponding hydrocarbon parameters provides an explanation of the abnormal polymorphism of these glycerides. 相似文献