Sn1-xBixO2 and Sn1-xTaxO2 (0 \leq x \leq 0.75): A first-principles study

The structural, elastic, electronic and optical (x = 0) properties of doped Sn1-xBixO2 and Sn1-xTaxO2 (0 \leq x \leq 0.75) are studied by using the first-principles pseudopotential plane-wave method within the local density approximation. The independent elastic constants Cij and other elastic parameters of these compounds have been calculated for the first time. The mechanical stability of the compounds with different doping concentrations has also been studied. The electronic band structure and density of states are calculated and the effect of doping on these properties is also analyzed. It is seen that the band gap of the undoped compound narrowed with dopant concentration which disappeared for x = 0.26 for Bi doping and 0.36 for Ta doping. The materials thus become conductive oxides through the change in the electronic properties of the compound for x \leq 0.75 which may be useful for potential application. The calculated optical properties, e.g. dielectric function, refractive index, absorption spectrum, loss-function, reflectivity and conductivity of the undoped SnO2 in two polarization directions are compared with both previous calculations and measurements. Keywords: Doped SnO2; First-principles; Mechanical properties; Electronic band structure; Optical properties.Comment: 10 pages, 5 figures, added 10 more references, comparison with mearements mad

Investigation of Different Iontophoretic Currents Profiles for Short-Term Applications in Cosmetics

[EN] This study aimed at investigating the effect of electrical current profile upon the iontophoretic transport of (i) ascorbic acid (AA) and (ii) ellagic acid (EA), into porcine skin in vitro, and the impact of the physicochemical properties of both actives on their mechanism of transport when formulated in cosmetic compositions. The experiments were performed using a proprietary iontophoretic device containing a roller to apply the formulation. Three current profiles were tested: (i) galvanic direct current (DC), (ii) square unipolar pulse current (SPC), and (iii) galvanic direct current (DC) + pulse current (PC). The skin samples were collected at different sampling points, extracted and analyzed by HPLC. Results suggested that the DC + PC mode for only 5 min was able to significantly increase the delivery of AA from o/w cosmetic compositions. The use of this current profile might improve the skin penetration of AA due to electromigration and passive diffusion, the latter being facilitated by the physical enhancement method. The SPC mode significantly improved the passage of EA in its neutral form from cosmetic o/w formulations by electroosmosis. Tailoring specific electrical current modes considering the ionization state of active ingredients would allow the design of short and personalized cosmetic treatments that significantly improve the penetration efficiency of the active ingredients and possibly reduce the doses applied.This research was entirely funded by L'Oreal, France.Cázares-Delgadillo, J.; Planard-Luong, L.; Gregoire, S.; Serna-Jiménez, CE.; Singhal, M.; Kalia, YN.; Merino Sanjuán, V.... (2018). Investigation of Different Iontophoretic Currents Profiles for Short-Term Applications in Cosmetics. Pharmaceutics. 10(4). https://doi.org/10.3390/pharmaceutics10040266266104R. Hamad, A.-W., Al-Momani, W. M., Janakat, S., & A. Oran, S. (2009). Bioavailability of Ellagic Acid After Single Dose Administration Using HPLC. Pakistan Journal of Nutrition, 8(10), 1661-1664. doi:10.3923/pjn.2009.1661.1664Kalia, Y. N., Naik, A., Garrison, J., & Guy, R. H. (2004). Iontophoretic drug delivery. Advanced Drug Delivery Reviews, 56(5), 619-658. doi:10.1016/j.addr.2003.10.026Marro, D., Kalia, Y. N., Begoña Delgado‐Charro, M., & Guy, R. H. (2001). Pharmaceutical Research, 18(12), 1701-1708. doi:10.1023/a:1013318412527Sobhi, R. M., & Sobhi, A. M. (2012). A single-blinded comparative study between the use of glycolic acid 70% peel and the use of topical nanosome vitamin C iontophoresis in the treatment of melasma. Journal of Cosmetic Dermatology, 11(1), 65-71. doi:10.1111/j.1473-2165.2011.00599.xHori, Y., Akimoto, R., Hori, A., Kato, K., Chino, D., Matsumoto, S., … Watanabe, Y. (2010). Skin collagen reproduction increased by ascorbic acid derivative iontophoresis by frequent-reversal bipolar electric stimulation. International Journal of Cosmetic Science, 32(3), 234-234. doi:10.1111/j.1468-2494.2010.00577_3.xJunyaprasert, V. B., Singhsa, P., Suksiriworapong, J., & Chantasart, D. (2012). Physicochemical properties and skin permeation of Span 60/Tween 60 niosomes of ellagic acid. International Journal of Pharmaceutics, 423(2), 303-311. doi:10.1016/j.ijpharm.2011.11.032Maia, A. M., Baby, A. R., Pinto, C. A. S. O., Yasaka, W. J., Suenaga, E., Kaneko, T. M., & Velasco, M. V. R. (2006). Influence of sodium metabisulfite and glutathione on the stability of vitamin C in O/W emulsion and extemporaneous aqueous gel. International Journal of Pharmaceutics, 322(1-2), 130-135. doi:10.1016/j.ijpharm.2006.05.03

Contribution a la determination des mecanismes de transport du D-pantothenate et du L-lactate par des vesicules membranaires de bordure en brosse isolees de rein de lapin

CNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Développement d'une source laser IR & visible, compacte, fibrée, stabilisée en fréquence

This project aims to develop a fully-fibered, frequency stabilized laser system, in a very compact architecture. Based on a C-band optical telecommunications source, it uses a novel and efficient frequency-tripling method combined with stabilisation to an atomic reference. The target is to meet the needs of many space missions requiring ultrastable optical links, such as eLISA dedicated to gravitationnel wave detection in space, GRACE Follow On for Earth gravity measurements or GRICE for space geodesy. The stabilized laser could also be applied to long distance and high-speed terrestrial optical communications.Le projet vise à développer un dispositif laser stabilisé de grandes performances métrologiques, très compact, et fibré . La source laser émet dans la bande C des Telecom optiques, triplée en fréquence selon un processus original et très efficace. Il vise à répondre aux besoins de projets spatiaux nécessitant un lien optique ultra-stable (inter-satellites ou bord sol). Ces missions spatiales sont par exemple celles dédiées à la détection d'ondes gravitationnelles dans l'espace (eLISA), à la mesure du champ gravitationnel terrestre (GRACE Follow On), à la géodésie spatiale (GRICE) etc .. Le laser stabilisé est susceptible de servir aussi pour les communications optiques terrestres longue distance et a haut débit, et qui requièrent une grande longueur de cohérence

Frequency stabilization of an IR & visible laser source

Le projet vise à développer un dispositif laser stabilisé de grandes performances métrologiques, très compact, et fibré . La source laser émet dans la bande C des Telecom optiques, triplée en fréquence selon un processus original et très efficace. Il vise à répondre aux besoins de projets spatiaux nécessitant un lien optique ultra-stable (inter-satellites ou bord sol). Ces missions spatiales sont par exemple celles dédiées à la détection d'ondes gravitationnelles dans l'espace (eLISA), à la mesure du champ gravitationnel terrestre (GRACE Follow On), à la géodésie spatiale (GRICE) etc .. Le laser stabilisé est susceptible de servir aussi pour les communications optiques terrestres longue distance et a haut débit, et qui requièrent une grande longueur de cohérence.This project aims to develop a fully-fibered, frequency stabilized laser system, in a very compact architecture. Based on a C-band optical telecommunications source, it uses a novel and efficient frequency-tripling method combined with stabilisation to an atomic reference. The target is to meet the needs of many space missions requiring ultrastable optical links, such as eLISA dedicated to gravitationnel wave detection in space, GRACE Follow On for Earth gravity measurements or GRICE for space geodesy. The stabilized laser could also be applied to long distance and high-speed terrestrial optical communications

Simulation of Surface Reactions

Abstract: Advances in high-temperature material synthesis and processing necessitate better understanding of underlying surface processes. Both physical and chemical transformations are of concern, those underlying surface reconstructon, film growth, and material etching. While classical thermodynamic description may suffice for some aspects, dynamic evolution and coupling to reactant flow is of growing practical importance. The scientific challenge is to explain macroscopic phenomena in terms of atomistic processes. This manuscript reviews a theoretical approach for going from an atomistic level to mesoscale description to macroscale phenomena. The methods includes quantum-mechanical calculations of surface models, time-dependent Monte Carlo simulations using reaction probabilities derived from the quantum-mechanical calculations, and kinetic modeling parameterized to the Monte Carlo results. The examples are drawn from the fields of silicon, diamond, and carbon materials, stressing the methodology and emphasizing general features revealed by recent numerical simulations

Ab initio potential and variational transition state theory rate constant for H‐atom association with the diamond (111) surface

International audienceHigh‐level ab initio calculations were performed to determine accurate analytic potential energy functions for interactions a gas‐phase H‐atom has with H‐atoms attached to the diamond (111) surface and with C‐atom radical sites on this surface. The nonbonded potential between the gas‐phase H‐atom and H‐atoms attached to the surface was determined from coupled‐cluster ab initio calculations, including single, double, and perturbatively applied triple excitations [CCSD(T)], with the 6‐311++G(2df,p) basis set. The resulting nonbonded potential is nearly identical to that found previously from both theory and experiment for interactions between H‐atoms on different hydrocarbon molecules. In the ab initio calculations, a C‐atom radical site on the diamond surface is represented by a constrained tert‐butyl radical. Radial and small‐displacement angular potentials for a H‐atom interacting with this radical were determined from unrestricted quadratic configuration interaction calculations, with single, double and perturbatively applied triple excitations [UQCISD(T)], with the 6‐31G∗∗ basis set. UQCISD(T) calculations were performed on the H+CH3→CH4 reaction system with both the 6‐31G∗∗ and 6‐311++G(3df,3pd) basis sets to calibrate the accuracy of the 6‐31G∗∗ basis set results for the H‐atom plus constrained tert‐butyl radical. The above information was used to construct an analytic potential energy function for H‐atom association with a radical site on the (111) surface of diamond, which was then employed in a canonical variational transition state theory (CVTST) calculation of the association rate constant. The resulting rate constant is 1.8-2.1×1013 cm3 mol−1 s−1 for the 1000-2000 K temperature range. It is insensitive to the gas‐phase H‐atom/surface H‐atom nonbonded potential and the potential for the diamond lattice. The H+diamond (111) CVTST rate constant is used to estimate a rate constant of 4×1013 cm3 mol−1 s−1 for H+tert‐butyl association at 298 K. The UQCISD(T)/6‐31G∗ calculations give a H--C(CH3)3 bond dissociation energy which is only 1 kcal/mol lower than the experimental value

Compact and ultra stable infrared lasers for ground tests of the LISA mission payload

International audienceWe plan to develop a compact and transportable iodine frequency stabilized laser setup, as part of the French activities by a consortium of several partners for assembly-integration and ground tests of the LISA payload. We take advantage of an existing laser frequency stabilization experiment based on a Telecom laser diode at 1544 nm, frequency tripled and stabilized against a narrow iodine line at 514 nm. The residual frequency noise already achieved for this experiment is below the LISA mission requirements. We achieve a reproducible frequency stability below 2.5x10-14-1/2 decreasing to 3.5x10-15 level after 200 s of integration time. It corresponds to an amplitude spectral density of the frequency fluctuations 15 Hz/√Hz. Furthermore, we demonstrate the ability to transfer the frequency stability achieved around 1.5 µm to the near infrared range, close to 1 µm, in a simple manner, using the usual phase locking loop technique associated to a second harmonic generation process. Thus, we propose to provide a 1064 nm laser source phase-locked to an iodine stabilized Telecom laser operating at 1596 nm. The compact design of the whole setup will make it easily transportable to different sites and could be readily used for ground tests of the LISA payload