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1.
M. E. Carlotti S. Sapino R. Cavalli M. Trotta F. Trotta K. Martina 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):445-450
This work deals with the formation of inclusion complexes between cinnamaldehyde and two synthetic alkylcarbonates of γ-cyclodextrin, namely ethylcarbonate-γ-CD and octylcarbonate-γ-CD. Complexation was monitored by phase-solubility studies, by FT-IR spectroscopy and by DSC and TG analysis.
The diffusion of cinnamaldehyde through a cellulose membrane was investigated in the absence and in the presence of each of
the two γ-CD alkylcarbonates. Studies on photostability and stability over time were carried out on different cosmetic formulations
containing pure cinnamaldehyde or an equivalent amount of cinnamaldehyde complexed with the two alkylcarbonates.
Phase-solubility diagrams, DSC, FTIR and TGA analysis suggested the formation of inclusion complexes. The diffusion of cinnamaldehyde
through the cellulose membrane decreased in the presence of the two alkylcarbonates confirming the interaction of this molecule
with the inclusion agents.
Moreover the stability of cinnamaldehyde to light and heat resulted increased by complexing this fragrance material with the
two alkylcarbonates. 相似文献
2.
3.
Eugenio Hernández Xihua Wang Guido Weiss 《Journal of Fourier Analysis and Applications》1997,3(1):23-41
The main purpose of this paper is to give a procedure to “mollify” the low-pass filters of a large number ofMinimally Supported Frequency (MSF) wavelets so that the smoother functions obtained in this way are also low-pass filters for an MRA. Hence, we are able
to approximate (in the L
2
-norm) MSF wavelets by wavelets with any desired degree of smoothness on the Fourier transform side. Although the MSF wavelets
we consider are bandlimited, this may not be true for their smooth approximations. This phenomena is related to the invariant
cycles under the transformation x ↦2x (mod2π). We also give a characterization of all low-pass filters for MSF wavelets. Throughout the paper new and interesting examples
of wavelets are described. 相似文献
4.
5.
6.
Eugenio?Garcia-Pa?eda Pilar?Guardado Alfredo?MaestreEmail author 《Journal of solution chemistry》2004,33(10):1277-1293
Partial molar volumes at infinite dilution, V02, of alkali–metal halides (LiCl, NaCl KCl RbCl CsCl, NaBr, KBr, KI), tetra-n-alkylammonium bromides, R4NBr (R=Me, Et, n-Pr, n-Bu, n-Pen), NaBPh4, and Ph4PCl have been determined in binary solvent mixtures of water with 2-methyl-2-butanol covering the water-rich region and the alcohol-rich region at 298.15 K. V02 for alkali–metal halides show relatively little dependence on the solvent composition. However, in the case of hydrophobic electrolytes the observed effects are more pronounced. A good linear dependence between V02(R4NBr) and the molecular weight of the tetra-n-alkylammonium cation is found. Limiting single-ion volumes have been obtained using the assumption that V0(Ph4P+)–V0(BPh–4)=2.0 cm3-mol–1. The trends in the single-ion volumes are discussed in both solvent regions. 相似文献
7.
Hereditarily finite sets and hypersets are characterized both as algorithmic data structures and by means of a first-order axiomatization which, despite being rather weak, suffices to make the following two problems decidable:
- (1) Establishing whether a conjunction r of formulae of the form: ? y1 ?? ym((y1?W1& ?&ym ?Wm) ←q), with q quantifier-free and involving only the relators =, ? and propositional connectives, and each yi distinct from all wj's, is satisfiable.
- (2) Establishing whether a formula of the form ? y q, q quantifier-free, is satisfiable.
8.
Paolesse R Monti D La Monica L Venanzi M Froiio A Nardis S Di Natale C Martinelli E D'Amico A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(11):2476-2483
Porphyrin diad 1 was synthesized by reaction of the acyl chloride of porphyrin 2 and trans-1,2-dithiane-4,5-diol. The Co complex of this diad was studied as a potential enantioselective receptor for chiral recognition in solution and in the solid state. In solution both enantiomers of limonene induce significant changes in the visible and circular dichroism (CD) spectra of [Co2(1)], while a different behavior is observed in the case of the enantiomeric pair of trans-1,2-diaminocyclohexane. A different efficiency of [Co2(1)] chiral recognition is obtained for these compounds, with a remarkable degree of enantiodiscrimination observed in the case of limonene. Self-assembled monolayers of [Co2(1)] were deposited onto the gold electrodes of quartz crystal microbalances to be used as sensing materials of nanogravimetric sensors operating in the gas phase. The enantiodiscrimination properties of these sensors towards the enantiomeric pairs of chiral analytes have been studied. While in the case of analytes bearing donor ligand atoms we did not observe a remarkable enantioselectivity, a significant degree of chiral discrimination was observed in the case of limonene; this result is particularly encouraging for the potential development of enantioselective chemical sensors for use in an array configuration. 相似文献
9.
Guido Barone Giuseppina Castronuovo Vittorio Crescenzi Vittorio Elia Eugenio Rizzo 《Journal of solution chemistry》1978,7(3):179-192
In order to clarify some aspects of the hydrophobic interactions, the enthalpies of dilution of monoethylurea, 1,3-dimethylurea,
and 1,3-diethylurea have been determined calorimetrically at 25°C. The calorimetric data, expressed in terms of excess enthalpy,
permit the evaluation of the pair and triplet interaction coefficients. The analyses of these and of the analogous coefficientsg
xx andg
xxx, derived from osmotic data, indicate a driving force favorable to the interactions among the hydrated solute molecules. Nevertheless,
the positive values of theh
xx andh
xxx coefficients seem to suggest that the source of the effect is a rearrangement of the water molecules rather than a direct
association of the solute molecules. There are evidences of a strict correlation between the enthalpic and the entropic effects.
Preliminary data were presented at the International Conferences on Chemical Thermodynamics at Baden (1973) and Montpellier
(1975). The experimental part was carried out at the Istituto Chimico of the University of Trieste.
To whom correspondence should be addressed. 相似文献
10.
Summary The present paper reports a rapid HPIC method for the determination of tetramethylammonium chloride in aqueous matrices which are used as food simulants in migration tests. These simulants were: bidistilled water, an aqueous solution of 3% acetic acid, an aqueous solution of 15% ethyl alcohol, a mixed aqueous solution of 3% acetic acid and 15% ethyl alcohol. The method, as developed, has been applied to the determination of unreacted tetramethylammonium chloride residues which are able to migrate from finished epoxy resins which are used as food packaging materials.Research partially supported by National Research Council of Italy, Special Project RAISA, sub-project 4, Paper No 695. 相似文献