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151.
152.
Floriane Morel Eliane Espuche Véronique Bounor‐Legaré Olivia Persynn Marc Lacroix 《Journal of Polymer Science.Polymer Physics》2016,54(6):649-658
Amorphous poly(lactide) (PLA) and nanocomposite films were prepared from melt‐blending with precipitated calcium carbonate nanofillers (PCC). Nanocomposites based on uncoated PCC (PCC‐UT), stearic acid coated PCC (PCC‐S), and poly(ε‐caprolactone) coated PCC (PCC‐P) were investigated for an inorganic content fixed to 8 wt %. Using coated nanofillers allowed preserving both PLA average molar mass and thermal stability while enhancing the nanofiller dispersion state. Poly(ε‐caprolactone) was identified as the best coating for optimized morphology and thermal properties. Maxwell law accurately described the increase in oxygen barrier properties observed for the nanocomposites based on PCC‐S. A modified Maxwell law was proposed to take account of the additional increase in barrier properties evidenced for the PLA/PCC‐P nanocomposites and assigned to the particularly strong compatibility between PCL and PLA. Different annealing conditions were investigated to respectively study the impact of physical ageing and PLA crystallization on gas permeability. Different extents of physical ageing did not significantly modify the oxygen transport properties. However, a high permeability decrease was observed for the semicrystalline nanocomposites with respect to the amorphous reference PLA film. Finally, the gain in barrier properties was shown to result from both contribution of the nanofillers and the crystalline phase. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 649–658 相似文献
153.
Milena Marinovi?-Cincovi? 《Polymer Degradation and Stability》2007,92(1):70-74
Colloidal dispersions consisting of β-FeOOH nanorods with three different aspect ratios (4, 75 and 120) were synthesized using thermal hydrolysis of FeCl3 solutions. After surface modification with oleic acid, the β-FeOOH nanorods were incorporated in poly(methyl methacrylate). Transmission electron microscopy and X-ray diffraction were applied for structural characterization of the β-FeOOH nanorods. The influence of inorganic phase on the thermal properties of PMMA matrix was studied using thermogravimetry and differential scanning calorimetry. Improvement of the thermal stability and increase of the glass transition temperature were found with the increase of content of inorganic phase and the increase of aspect ratio. 相似文献
154.
Dušan Malešev Zorica Radović Milena Jelikić-Stankov 《Monatshefte für Chemie / Chemical Monthly》1990,121(6-7):455-460
Summary By the application of suitable spectrophotometric methods andpH-metric measurements it has been established that uranyl ion and 3-hydroxyflavone form a [UO2(C15H9O3)]+ complex. The concentration stability constant of the complex was determined by Bent-French's (1=8.59 atpH=3.5) and Bjerrum's (from 8.68 atpH=4 to 6.14 atpH=7) methods. Conditions are given for the spectrophotometric determination of 3-hydroxyflavone by means of the complex. The regression equation is calculated and the accuracy of the method is determined. All investigations were carried out with 80% ethanolic solutions at room temperature (20°), the spectrophotometric measurements being performed at a constantpH (3.5) and a constant ionic strength (0.01M).
Untersuchung des Uranil(II)—3-Hydroxyflavon-Komplexes
Zusammenfassung Unter der Anwendung von geeigneten spektrophotometrischen Methoden sowiepH-metrischen Messungen wurde gefunden, daß das UO 2 2+ -Ion und 3-Hydroxyflavon den Komplex [UO2(C15H9O3)]+ bilden. Die Stabilitätskonstante des Komplexes wurde nach Bent und French (1=8.59 beipH=3.5) und nach Bjerrum (von 8.68 beipH=4 bis 6.14 beipH=7) bestimmt. Es werden die Bedingungen für die spektrophotometrische Bestimmung des 3-Hydroxyflavons mit Hilfe des Komplexes angegeben, die Regreßgleichung berechnet und die Genauigkeit der Methode ermittelt. Alle Untersuchungen wurden in 80proz. Ethanol bei Raumtemperatur (20°), die spektrophotometrischen Untersuchungen bei konstantempH-Wert und Ionenstärke (0.01M) durchgeführt.相似文献
155.
Milena Pintarič Svetozar Milićev Bogdan Volavšek 《Monatshefte für Chemie / Chemical Monthly》1990,121(5):357-360
Summary Two microcristalline phases have been isolated from aqueous solutions: (NH3OH)2AlF5(A) and (NH3OH)AlF4·H2O(B). They crystallize in the orthorhombic system with cell parameters for A:a=6.475 (3) Å,b=7.295 (3) Å,c=10.827 (5) Å, and for B:a=7.003 (3) Å,b=8.489 (4) Å,c=10.745 (5) Å. The Hydroxylammonium-aluminates were characterized by vibrational spectroscopy and their thermal decomposition studied by DSC and TG analysis. 相似文献
156.
Aleksandra R. Zarubica Milena N. Miljkovic Ern E. Kiss Goran C. Boskovic 《Reaction Kinetics and Catalysis Letters》2007,90(1):145-150
Activities of two catalysts obtained from hydroxide and alkoxide precursors were correlated to their different structural
and textural properties. Activity is mainly determined by the presence of active tetragonal phase, which is more stable at
high temperatures in the catalyst of alkoxide origin than in one from hydroxide. An appropriate structure must be accompanied
with beneficial pore structure, as is the case of mesopores of the catalyst from alkoxide. In the case of very small pores
of the catalyst from hydroxide precursor, activity is negligible due to pores plugged by coke. 相似文献
157.
158.
Gareth W. Harbottle Neil Feeder Karl R. Gibson Mel Glossop Graham N. Maw William A. Million Florence F. Morel Simon Osborne Cedric Poinsard 《Tetrahedron letters》2007,48(24):4293-4296
The syntheses of 6-fluoropyrido[3,4-d]pyrimidin-4-ylamine derivatives is reported herein. Methods for generating C, N and O linked analogues under microwave irradiation are described. 相似文献
159.
Sophie Morel 《Journal of the American Mathematical Society》2008,21(1):23-61
In this work, we calculate the trace of a Hecke correspondance composed with a power of the Frobenius endomorphism on the fibre of the intersection complexes of the Baily-Borel compactification of a Siegel modular variety.
Our main tool is Pink's theorem about the restriction to the strata of the Baily-Borel compactification of the direct image of a local system on the Shimura variety. To use this theorem, we give a new construction of the intermediate extension of a pure perverse sheaf as a weight truncation of the full direct image.
More generally, we are able to define analogs in positive characteristic of the weighted cohomology complexes introduced by Goresky, Harder and MacPherson.
160.
Ralitsa Chimshirova Milena Popova Amina Chakir Violeta Valcheva Simeon Dimitrov Boryana Trusheva Abderrahmane Romane Vassya Bankova 《Molecules (Basel, Switzerland)》2022,27(7)
The chemical composition and antimicrobial activity of propolis from a semi-arid region of Morocco were investigated. Fifteen compounds, including triterpenoids (1, 2, 7–12), macrocyclic diterpenes of ingol type (3–6) and aromatic derivatives (13–15), were isolated by various chromatographic methods. Their structures were elucidated by a combination of spectroscopic and chiroptical methods. Compounds 1 and 3 are new natural compounds, and 2, 4–6, and 9–11 are newly isolated from propolis. Moreover, the full nuclear magnetic resonance (NMR) assignments of three of the known compounds (2, 4 and 5) were reported for the first time. Most of the compounds tested, especially the diterpenes 3, 4, and 6, exhibited very good activity against different strains of bacteria and fungi. Compound 3 showed the strongest activity with minimum inhibitory concentrations (MICs) in the range of 4–64 µg/mL. The combination of isolated triterpenoids and ingol diterpenes was found to be characteristic for Euphorbia spp., and Euphorbia officinarum subsp. echinus could be suggested as a probable and new plant source of propolis. 相似文献