Search results for "absorption."

Reactive and organic halogen species in three different European coastal environments

2005

We present results of three field campaigns using active longpath DOAS (Differential Optical Absorption Spectroscopy) for the study of reactive halogen species (RHS) BrO, IO, OIO and I2. Two recent field campaigns took place in Spring 2002 in Dagebüll at the German North Sea Coast and in Spring 2003 in Lilia at the French Atlantic Coast of Brittany. In addition, data from a campaign in Mace Head, Ireland in 1998 was partly re-evaluated. During the recent field campaigns volatile halogenated organic compounds (VHOCs) were determined by a capillary gas chromatograph coupled with an electron capture detector and an inductively coupled plasma mass spectrometer (GC/ECD-ICPMS) in air and wat…

Modelling the optical properties of fresh biomass burning aerosol produced in a smoke chamber: results from the EFEU campaign

2007

A better characterisation of the optical properties of biomass burning aerosol as a function of the burning conditions is required in order to quantify their effects on climate and atmospheric chemistry. Controlled laboratory combustion experiments with different fuel types were carried out at the combustion facility of the Max Planck Institute for Chemistry (Mainz, Germany) as part of the "Impact of Vegetation Fires on the Composition and Circulation of the Atmosphere" (EFEU) project. The combustion conditions were monitored with concomitant CO<sub>2</sub> and CO measurements. The mass scattering efficiencies of 8.9±0.2 m<sup>2</sup> g<sup&gt…

Model, software, and database for line-mixing effects in the ν3 and ν4 bands of CH4 and tests using laboratory and planetary measurements. I. N2 (and…

2006

Absorption spectra of the infrared ν3 and ν4 bands of CH4 perturbed by N2 over large ranges of pressure and temperature have been measured in the laboratory. A theoretical approach accounting for line mixing is proposed to (successfully) model these experiments. It is similar to that of Pieroni et al. [J Chem Phys 1999;110:7717–32] and is based on state-to-state rotational cross-sections calculated with a semi-classical approach and a few empirical parameters. The latter, which enable switching from the state space to the line space, are deduced from a fit of a single room temperature spectrum of the ν3 band at 50 atm. The comparisons between numerous measured and calculated spectra under a…

Redshifted Cherenkov Radiation for in vivo Imaging: Coupling Cherenkov Radiation Energy Transfer to multiple Förster Resonance Energy Transfers

2017

AbstractCherenkov Radiation (CR), this blue glow seen in nuclear reactors, is an optical light originating from energetic β-emitter radionuclides. CR emitter 90Y triggers a cascade of energy transfers in the presence of a mixed population of fluorophores (which each other match their respective absorption and emission maxima): Cherenkov Radiation Energy Transfer (CRET) first, followed by multiple Förster Resonance Energy transfers (FRET): CRET ratios were calculated to give a rough estimate of the transfer efficiency. While CR is blue-weighted (300–500 nm), such cascades of Energy Transfers allowed to get a) fluorescence emission up to 710 nm, which is beyond the main CR window and within t…

Role of intestinal epithelial CD36 in obesity and endotoxemia driven by lipid absorption

2021

Intestinal dysbiosis, increased permeability and inflammation are the hallmarks in obese patients, highlighting the role of small intestine beyond providing with calories. CD36 is a ubiquitous scavenger receptor that exhibits high binding affinity for long-chain fatty acids and is highly expressed in enterocytes, endothelial and immune cells. Interestingly, CD36-/- mice and humans with CD36 polymorphisms have an impaired synthesis of triglyceride-rich lipoprotein (TRL). To evaluate the role of CD36 expressed by intestinal-epithelial cells (IEC) in obesity, we conducted experiments on male and female mice deleted in CD36 in IEC (ENT-KO) and control mice (ENT-FL), under standard and high-fat …

Recently identified microbial guild mediates soil N2O sink capacity

2015

Interdiction des procédures d'exécution. Absorption de la société caution inopposable à un créancier de la société débitrice. Possibilité de saisie d…

2021

International audience; (Com. 7 oct. 2020, n° 19-14.755, arrêt n° 609 FS-P+B, Sté Almendricos et a. c/ Sté Crédit foncier de France, D. 2021. 458, obs. G. Sebban ; Rev. sociétés 2020. 709, obs. F. Reille ; JCP 2020. 1220)

Recent developments in the acoustical properties of perforated and porous materials containing dead-end pores

2017

It was shown recently in Nevers, France, Sherbrooke, Canada and Salford, UK, that porous materials with semi-opened pores or materials with open pores bearing lateral cavities or resonators at the microscopic scale of the pores can result in peculiar sound absorption properties. Various examples of these materials can be found in engineering and in everyday life including bio-based materials. The cavities and resonators can be assimilated to dead-end pores, which are opened at one end and closed at the other. The dead-end pores are known to geophysicists. We studied them more recently in the field of engineering acoustics where the saturating fluid is air. The closed ends prevent the fluid …

Acoustical properties of air-saturated porous material with periodically distributed dead-end pores

2015

International audience; A theoretical and numerical study of the sound propagation in air-saturated porous media with straight main pores bearing lateral cavities (dead-ends) is presented. The lateral cavities are located at " nodes " periodically spaced along each main pore. The effect of periodicity in the distribution of the lateral cavities is studied, and the low frequency limit valid for the closely spaced dead-ends is considered separately. It is shown that the absorption coefficient and transmission loss are influenced by the viscous and thermal losses in the main pores as well as their perforation rate. The presence of long or short dead-ends significantly alters the acoustical pro…

On the Schwarzschild Effect in 3D Two‐Photon Laser Lithography

2019

International audience; The two‐photon Schwarzschild effect in photoresists suitable for 3D laser lithography is revisited. The study ranges over seven orders of magnitude in exposure time (from 1 µs to 10 s) and investigates a wide variety of different photoresist compositions. For short exposure times (“regime I”), the laser power at the polymerization threshold can scale with the inverse square root of the exposure time, as naively to be expected for two‐photon absorption. Substantial deviations occur, however, for low photoinitiator concentrations. For intermediate exposure times (“regime II”), a Schwarzschild‐type of behavior is found, as discussed previously. For very long exposure ti…