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101.
Antoine Giovanni Maurice Ouaknine Bruno Guelfucci Ping Yu Michel Zanaret Jean-Michel Triglia 《Journal of voice》1999,13(4):465-476
Coupling between the vocal folds is one of the nonlinear mechanisms allowing regulation and synchronization of mucosal vibration. The purpose of this study was to establish that modulations such as diplophonia and abnormalities observed in vocal signals that may be observed in some cases of laryngeal pathology can be considered as nonlinear behavior due to the persistence of some physical interaction (coupling). An experimental model using excised porcine larynx was designed to create tension asymmetry between the vocal folds and to obtain vocal signals with modulations. Signals were analyzed by spectral analysis and the phase portrait method. Results were compared with computer-generated synthetic signals corresponding to nonlinear combinations of sinusoid signals. Under these conditions, evidence of nonlinear behavior was detected in 85% of experimental signals. These findings were interpreted as a demonstration of vocal fold interaction. Based on these findings, the authors conclude that (1) coupling must be taken into account in physical models of laryngeal physiology, and that (2) methods of nonlinear dynamics may be used for objective voice analysis. 相似文献
102.
Mei Wen Jean-Michel Chabagno Gary Silverman Maurice Bourrel 《Journal of Non》2008,354(45-46):5060-5067
Edge-strengthening is a novel technology used to strengthen glass by applying a coating only on the edges. In this work, edge flaws of flat glass articles were examined in detail via scanning electron microscope (SEM) imaging. Then the effect of using weatherable acrylate coatings on edge-strengthening of flat glass was determined. Four-point bending measurement showed that the coatings provided more than twofold increase of the mean flexural strength and a factor of about two increase of the tensile stress needed to reach 0.8% cumulative probability of failure. The coatings were found to cover the flaw zone at the glass edges and partially fill in the cracks. Different surface treatments led to different levels of strengthening, indicating the importance of coating adhesion. The coating’s thermal and mechanical properties affected the extent of strengthening effect. A coating formulation with a higher glass transition temperature tended to provide a better strengthening effect, indicating the importance of closure stress within cracks generated during film curing process. Challenges of applying the edge-strengthening technology are also discussed. 相似文献
103.
Tanguy Pier Khalid Kandoussi Claude Simon Nathalie Coulon Tayeb Mohammed-Brahim Hervé Lhermite 《Journal of Non》2008,354(19-25):2300-2304
Microcrystalline silicon (μc-Si) films have been deposited on PDMS as well as on PEN substrate. Excimer laser annealing was used to improve the crystalline structure and so to obtain high mobility TFTs. The effect of the laser annealing on the crystalline structure of silicon films is studied using different characterization techniques and discussed. Mobility values of 60 cm2/V s with PDMS and 46 cm2/V s with PEN are obtained. 相似文献
104.
105.
The photoinduced dynamics of isolated n-hydroxyquinoline (nHQ) molecules (n=6,8) was investigated in femtosecond pump-probe experiments. A qualitative difference was found between 8HQ and 6HQ. After an initial rapid decay corresponding to the departure of the initial wavepacket out of the Franck-Condon region of the excitation, the 8HQ probe signal decays to zero in 0.37 ps whereas a much longer time constant of 10.4 ps is observed in 6HQ. This interrogates on the role played by the intramolecular H-bond N HO which is at play the 8HQ molecule. Ab-initio were performed at the MCSCF/aug-cc-pVDZ level on the 8HQ molecule to help the discussion. A complex energy landscape was found, which includes a conical intersection. 相似文献
106.
Florent Monie Dr. Bruno Grignard Dr. Jean-Michel Thomassin Dr. Raphael Mereau Dr. Thierry Tassaing Prof. Dr. Christine Jerome Dr. Christophe Detrembleur 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(39):17181-17189
Polyurethane (PU) foams are indisputably daily essential materials found in many applications, notably for comfort (for example, matrasses) or energy saving (for example, thermal insulation). Today, greener routes for their production are intensively searched for to avoid the use of toxic isocyanates. An easily scalable process for the simple construction of self-blown isocyanate-free PU foams by exploiting the organocatalyzed chemo- and regioselective additions of amines and thiols to easily accessible cyclic carbonates is described. These reactions are first validated on model compounds and rationalized by DFT calculations. Various foams are then prepared and characterized in terms of morphology and mechanical properties, and the scope of the process is illustrated by modulating the composition of the reactive formulation. With impressive diversity and accessibility of the main components of the formulations, this new robust and solvent-free process could open avenues for construction of more sustainable PU foams, and offers the first realistic alternative to the traditional isocyanate route. 相似文献
107.
Le Nel A Minc N Smadja C Slovakova M Bilkova Z Peyrin JM Viovy JL Taverna M 《Lab on a chip》2008,8(2):294-301
A microreactor for proteinase K (PK)-mediated protein digestion was developed as a step towards the elaboration of a fully integrated microdevice for the detection of pathological prion protein (PrP). PK-grafted magnetic beads were immobilized inside a polydimethylsiloxane (PDMS) microchannel using a longitudinal magnetic field parallel to the flow direction and a magnetic field gradient, thereby forming a matrix for enzymatic digestion. This self-organization provided uniform pore sizes, a low flow resistance and a strong reaction efficiency due to a very thin diffusion layer. The microreactor's performance was first evaluated using a model substrate, succinyl-ala-ala-ala-paranitroanilide (SAAAP). Reaction kinetics were typically accelerated a hundred-fold as compared to conventional batch reactions. Reproducibility was around 98% for on-chip experiments. This microsystem was then applied to the digestion of prion protein from brain tissues. Controlled proteolysis could be obtained by varying the on-chip flow rate, while a complete proteolysis of normal protein was achieved in only three minutes. Extracts from normal and pathological brain homogenates were finally compared and strong discrimination between normal and pathological samples was demonstrated. 相似文献
108.
Nalophan bags made from poly(ethylene terephtalate) film are often used to collect odorous gases. In this paper, the sample water removal method, based on humidity diffusion through the sample bag film, was applied using Nalophan bags and Tedlar bags to sample volatile organic compounds (VOCs) at low concentration (10 microg/m(3)). The removal of water with Nalophan bags enabled a reduction in relative humidity (RH) in a 10-L air sample from 80% to 20% in 2h at 20 degrees C. The use of Nalophan bags for the removal of water did not involve significant VOC loss among the 11 compounds studied. 相似文献
109.
Poisson L Roubin P Coussan S Soep B Mestdagh JM 《Journal of the American Chemical Society》2008,130(10):2974-2983
The dynamics of the enolic form of acetylacetone (E-AcAc) was investigated using a femtosecond pump-probe experiment. The pump at 266 nm excited E-AcAc in the first bright state, S2(pi pi*). The resulting dynamics was probed by multiphoton ionization at 800 nm. It was investigated for 80 ps on the S2(pi pi*) and S1(n pi*) potential energy surfaces. An important step is the transfer from S2 to S1 that occurs with a time constant of 1.4 +/- 0.2 ps. Before, the system had left the excitation region in 70 +/- 10 fs. An intermediate step was identified when E-AcAc traveled on the S2 surface. Likely, it corresponds to an accidental resonance in the detection scheme that is met along this path. More importantly, some clues are given that an intramolecular vibrational energy relaxation is observed, which transfers excess vibrational energy from the enolic group O-H to the other modes of the molecule. The present multistep evolution of excited E-AcAc probably also describes, at least qualitatively, the dynamics of other electronically excited beta-diketones. 相似文献
110.
Costentin C Louault C Robert M Savéant JM 《Journal of the American Chemical Society》2008,130(47):15817-15819
Proton-coupled electron transfer oxidation of phenols play a prominent role in several natural processes, and one may wonder if their high efficiency is related to the possibility that the electron and proton transfer steps are concerted. The cyclic voltammetric observation of the electrochemical oxidation and reverse reaction has allowed, with the example of 2,4,6-tri-tert-butylphenol in nonbuffered aqueous media, the clear identification of a pathway in which a phenol is directly and reversibly converted into the phenoxyl radical while the generated proton is accepted by a water molecule in a concerted manner. In very basic media, a stepwise mechanism takes place in which the phenol is deprotonated by OH- and the resulting phenoxide ion rapidly oxidized into the phenoxyl radical. As the pH decreases, this pathway progressively shuts down to the advantage of the concerted pathway. The latter assignment is confirmed by the observation of a substantial H/D kinetic isotope effect. At moderately basic pH 10.5, the contributions of the two pathways are about equal and the occurrence of the two competing routes is directly visualized in the cyclic voltammetry response. 相似文献