Search results for " Fourier"
showing 10 items of 478 documents
New Biodegradable Hydrogels Based on Inulin and α,β-Polyaspartylhydrazide Designed for Colonic Drug Delivery: In Vitro Release of Glutathione and Oxy…
2010
Succinic derivatives of inulin (INU-SA) with two different degrees of derivatization (20% and 30%, mol/mol) were cross-linked with α,β-polyaspartylhydrazide (PAHy) to obtain INUPAHy hydrogels. Cross-linking was performed using N-ethyl-N-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (NHSS) as coupling agents and by varying the reaction time (4 h, 8 h and 24 h). All samples prepared were characterized by FT-IR analysis and swelling measurements in different media. In vitro assays, performed in the presence of inulinase, demonstrated the degradability of the prepared hydrogels. Cell compatibility was evaluated using Caco-2 cells through both direct and …
Classification of Pecorino cheeses produced in Italy according to their ripening time and manufacturing technique using Fourier transform infrared sp…
2010
Fourier-transform infrared spectroscopy, followed by linear discriminant analysis of the spectral data, was used to classify Italian Pecorino cheeses according to their ripening time and manufacturing technique. The Fourier transform infrared spectra of the cheeses were divided into 18 regions and the normalized absorbance peak areas within these regions were used as predictors. Linear discriminant analysis models were constructed to classify Pecorino cheeses according to different ripening stages (hard and semi-hard) or according to their manufacturing technique (fossa and nonfossa cheeses). An excellent resolution was achieved according to both ripening time and manufacturing technique. A…
Interaction of an odorant lactone with model phospholipid bilayers and its strong fluidizing action in yeast membrane
2003
International audience; Some odorant lactones are naturally present in fruits or in fermented products; they can also be used as food additives and can be produced by microorganisms at the industrial scale by biotechnological processes. Gamma-decalactone was previously shown to have antimicrobial properties. We determined by infrared spectroscopy measurements that this compound rapidly diffused into model phospholipid bilayers (within 2 min), modifying the general physical state of a dimyristoyl-L-alpha-phosphatidylcholine (DMPC) film. In vivo, the lactone strongly increased membrane fluidity in the model yeast Yarrowia lipolytica, as evaluated by fluorescence anisotropy measurements. This …
Comparison of transflection and transmission FTIR imaging measurements performed on differentially fixed tissue sections
2015
The widespread and cost-effective use of transflection substrates in Fourier transform infrared (FTIR) imaging of clinical samples is affected by the presence of artefacts including the electric field standing wave (EFSW) and contributions from light dispersion. For IR-based diagnostics, the manifestation of undesirable artifacts can distort the spectra and lead to erroneous diagnosis. Nevertheless, there is no clear consensus in the literature about the degree of influence of these effects. The aim of this work is to contribute to this discussion by comparing transflection and transmission images of the same tissue. For this purpose two adjacent sections of the same tissue (lymphoma sample…
Hydrothermal Synthesis of Ionic Liquid [Bmim]OH-Modified TiO2 Nanoparticles with Enhanced Photocatalytic Activity under Visible Light
2010
TiO(2) nanocomposites modified with the ionic liquid [Bmim]OH are synthesized by a hydrothermal procedure. X-ray diffraction, Zeta-potential measurement, TEM, thermogravimetric analysis, photoluminescence, UV/Vis, FTIR, and X-ray photoelectron spectroscopy are used to characterize the TiO(2) nanocomposites. The TiO(2) nanocomposites consist of pure anatase particles of about 10 nm. The modification of [Bmim]OH on the surface of the TiO(2) particles extends the TiO(2) absorption edge to the visible-light region. The electrochemical redox potentials indicated that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of [Bmim]OH match well with the valen…
High-Performance TiO2 Nanoparticle/DOPA-Polymer Composites
2014
Many natural materials are complex composites whose mechanical properties are often outstanding considering the weak constituents from which they are assembled. Nacre, made of inorganic (CaCO 3 ) and organic constituents, is a textbook example because of its strength and toughness, which are related to its hierarchical structure and its well-defi ned organic–inorganic interface. Emulating the construction principles of nacre using simple inorganic materials and polymers is essential for understanding how chemical composition and structure determine biomaterial functions. A hard multilayered nanocomposite is assembled based on alternating layers of TiO 2 nanoparticles and a 3-hydroxytyramine…
Lipid phase transition in saccharide-coated cholate-containing liposomes: coupling to the surrounding matrix.
2005
We performed FTIR measurements on cholate-containing liposomes (CCL) embedded in saccharide (trehalose or sucrose) matrixes with different contents of residual water. We obtained information on the CCL phase transition following the thermal evolution (310-70 K) of the IR spectrum of the carbonyl moieties of phospholipids in the frequency range 4225-4550 cm(-1). Furthermore, we simultaneously followed the thermal evolution of the water association band, which gave information on the behavior of the surrounding water-saccharide matrix. The analysis revealed a small sub-band of the water association band present in CCL but not in cholate-free liposomes, the thermal evolution of which is tightl…
Morphometrics of Second Iron Age ceramics - strengths, weaknesses, and comparison with traditional typology.
2014
12 pages; International audience; Although the potential of geometric morphometrics for the study of archaeological artefacts is recognised, quantitative evaluations of the concordance between such methods and traditional typology are rare. The present work seeks to fill this gap, using as a case study a corpus of 154 complete ceramic vessels from the Bibracte oppidum (France), the capital of the Celtic tribe Aedui from the Second Iron Age. Two outline-based approaches were selected: the Elliptic Fourier Analysis and the Discrete Cosine Transform. They were combined with numerous methods of standardisation/normalisation. Although standardisations may use either perimeter or surface, the res…
Historia del pensamiento político moderno (08 Socialismo utópico)
2010
1.- Robert Owen / Padre del cooperativismo. 2.- Charles Fourier / Falansterios. 3.-Henri de Saint-Simón. Fabianismo. La Internacional. &&&&& Historia del Pensamiento Político Moderno. HPPM. La asignatura de Historia del Pensamiento Político se imparte en a la Licenciatura de Ciencias Políticas y de la Administración, Derecho y Sociología y en grado. Historia del Pensamiento Político Moderno tiene como objetivo ofrecer una visión de aspectos centrales del pensamiento político moderno, del siglo XVI al XX. Los textos de los autores escogidos constituyen el punto de apoyo fundamental en el desarrollo del programa, por lo que los estudiantes deben hacer una lectura previa al tratamiento de los …
Fractional-order theory of thermoelasticicty. I: Generalization of the Fourier equation
2018
The paper deals with the generalization of Fourier-type relations in the context of fractional-order calculus. The instantaneous temperature-flux equation of the Fourier-type diffusion is generalized, introducing a self-similar, fractal-type mass clustering at the micro scale. In this setting, the resulting conduction equation at the macro scale yields a Caputo's fractional derivative with order [0,1] of temperature gradient that generalizes the Fourier conduction equation. The order of the fractional-derivative has been related to the fractal assembly of the microstructure and some preliminary observations about the thermodynamical restrictions of the coefficients and the state functions r…