Search results for "RAMAN"
showing 10 items of 1328 documents
Regular consumption of fresh orange juice increases human skin carotenoid content
2015
Dermal carotenoids are a good indicator of antioxidant status in the body. This study aimed to determine whether regular consumption of orange juice could increase dermal carotenoids. Two types of orange juice, obtained from regularly (CI) and partially (PRD) irrigated trees, were tested to reveal any possible association between juice and dermal carotenoids. Soluble solids, titratable acidity, and total carotenoids were quantified in the juice; skin carotenoid score (SCS) was assessed by Raman spectroscopy. Carotenoid content was 7.3% higher in PRD than in CI juice, inducing no difference in SCS. In a first trial with daily juice intakes for 25 days, SCS increased linearly (10%) in the ind…
In vivo endomicroscopy improves detection of Barrett’s esophagus–related neoplasia: a multicenter international randomized controlled trial
2013
Background Confocal laser endomicroscopy (CLE) enables in vivo microscopic imaging of the GI tract mucosa. However, there are limited data on endoscope-based CLE (eCLE) for imaging Barrett's esophagus (BE). Objective To compare high-definition white-light endoscopy (HDWLE) alone with random biopsy (RB) and HDWLE + eCLE and targeted biopsy (TB) for diagnosis of BE neoplasia. Design Multicenter, randomized, controlled trial. Setting Academic medical centers. Patients Adult patients with BE undergoing routine surveillance or referred for early neoplasia. Intervention Patients were randomized to HDWLE + RB (group 1) or HDWLE + eCLE + TB (group 2). Real-time diagnoses and management plans were r…
Amorphous Silicon Nanotubes via Galvanic Displacement Deposition
2013
Amorphous silicon nanotubes were grown in a single step into a polycarbonate membrane by a galvanic displacement reaction conducted in aqueous solution. In order to optimize the process, a specifically designed galvanic cell was used. SEM images, after polycarbonate dissolution, showed interconnected nanotube bundles with an average length of 18 μm and wall thickness of 38 nm.The deposited silicon was revealed by EDS analysis, whilst X-ray diffraction and Raman spectroscopy showed that nanotubes have an amorphous structure. Silicon nanotubes were also characterized by photo-electrochemical measurements that showed n-type conductivity and optical gap of ~1.6 eV. Keywords: Silicon nanotubes, …
Collision de similaritons optiques dans un amplificateur optique fibré Raman
2005
National audience; Nous abordons les aspects théoriques et expérimentaux de la génération et propagation de deux similaritons optiques de fréquences centrales différentes dans un amplificateur optique fibré Raman à dispersion normale. Nous observons les effets intervenant durant la collision des deux similaritons: un battement sinusoïdal apparaît dans la zone de recouvrement temporel des impulsions et des effets de la modulation de phase croisée modifient le spectre des similaritons. Les similaritons retrouvent néanmoins, après collision, leurs caractéristiques paraboliques.
Ondes scélérates et statistiques extrêmes dans les systèmes optiques fibrés
2011
This thesis deals with extremes statistics which has become an attractive subject in optics since a comparison with oceanic rogue waves has been proposed at the end of 2007. We report some potential mechanisms stimulating the rogue wave formation in the context of guided propagation of light in optical fibers. In a first part, we explore optical rogue waves in supercontinuums generated by fourth-order modulation instability and we propose a stabilization method based on the use of two continuous seeds. Then, we present a detailed study on Raman fiber amplifiers where we determine the conditions of emergence of giant structures : in presence of a partially incoherent pumping wave, a quasi-in…
Decoding vibrational states of Concanavalin A amyloid fibrils.
2015
International audience; Amyloid and amyloid-like fibrils are a general class of protein aggregates and represent a central topic in life sciences for their involvement in several neurodegenerative disorders and their unique mechanical and supramolecular morphological properties. Both their biological role and their physical properties, including their high mechanical stability and thermodynamic inertia, are related to the structural arrangement of proteins in the aggregates at molecular level. Significant variations may exist in the supramolecular organization of the commonly termed cross-β structure that constitutes the amyloid core. In this context, a fine knowledge of the structural deta…
Inkjet printing Ag nanoparticles for SERS hot spots
2018
A novel inkjet printing based approach is developed for the fabrication of a customizable platform on glass substrates allowing for surface enhanced Raman spectroscopy (SERS) detection of analytes up to single hot spots generated by the spontaneous aggregation of Ag nanoparticles (Ag NPs) in pL scale droplets. After drying the printed droplets under ambient conditions, trace amounts of the analyte can be detected by SERS given the proximity to NP hot spots. By employing alizarin (10-5M) as a model system and scaling the ink droplet volume from 1 nL to 10 pL, the absolute quantity of hot spots has been derived in the printed droplets allowing detecting up to a few molecules in proximity to i…
Pressure-induced magnetic switching and linkage isomerism in K0.4Fe4[Cr(CN)6]2.8 x 16 H2O: X-ray absorption and magnetic circular dichroism studies.
2008
The effect of applied pressure on the magnetic properties of the Prussian blue analogue K0.4Fe4[Cr(CN)6]2.8 x 16 H2O (1) has been analyzed by dc and ac magnetic susceptibility measurements. Under ambient conditions, 1 orders ferromagnetically at a critical temperature (T(C)) of 18.5 K. Under application of pressure in the 0-1200 MPa range, the magnetization of the material decreases and its critical temperature shifts to lower temperatures, reaching T(C) = 7.5 K at 1200 MPa. Pressure-dependent Raman and Mossbauer spectroscopy measurements show that this striking behavior is due to the isomerization of some Cr(III)-C[triple bond]N-Fe(II) linkages to the Cr(III)-N[triple bond]C-Fe(II) form. A…
FT-Raman and QM/MM study of the interaction between histamine and DNA
2006
The interaction between histamine and highly polymerized calf-thymus DNA has been investigated using FT-Raman spectroscopy and the hybrid QM/MM (quantum mechanics/molecular mechanics) methodology. Raman spectra of solutions containing histamine and calf-thymus DNA, at different molar ratios, were recorded. Solutions were prepared at physiological settings of pH and ionic strength, using both natural and heavy water as the solvent. The analysis of the spectral changes on the DNA Raman spectra when adding different concentrations of histamine allowed us to identify the reactive sites of DNA and histamine, which were used to built two minor groove and one intercalated binding models. They were…
Stimulated Raman and Cars Spectroscopy of ν1 and 2ν2 (A1) Bands of 12CF4
1994
Two experimental coherent Raman techniques, stimulated Raman and coherent anti-Stokes Raman spectroscopy (CARS), were employed to study the Raman spectrum of CF 4 in the 900 cm −1 region. The stimulated Raman and CARS spectra of the ν 1 band of CF 4 were recorded at high resolution. The analysis of these spectra enabled some spectroscopic constants of this band to be refined and higher order constants to be determined for the first time. The first high-resolution CARS spectrum of the 2ν 2 (A 1 ) harmonic band is also presented. The rotational transitions of this band up to J = 40 were assigned and the first set of spectroscopic constants for this sub-level were determined. These results imp…