The presence of microplastics in commercial salts from different countries

This is the final version of the article. Available from Springer Nature via the DOI in this record.The corrigendum to this article is in ORE at http://hdl.handle.net/10871/34751The occurrence of microplastics (MPs) in saltwater bodies is relatively well studied, but nothing is known about their presence in most of the commercial salts that are widely consumed by humans across the globe. Here, we extracted MP-like particles larger than 149 μm from 17 salt brands originating from 8 different countries followed by the identification of their polymer composition using micro-Raman spectroscopy. Microplastics were absent in one brand while others contained between 1 to 10 MPs/Kg of salt. Out of the 72 extracted particles, 41.6% were plastic polymers, 23.6% were pigments, 5.50% were amorphous carbon, and 29.1% remained unidentified. The particle size (mean ± SD) was 515 ± 171 μm. The most common plastic polymers were polypropylene (40.0%) and polyethylene (33.3%). Fragments were the primary form of MPs (63.8%) followed by filaments (25.6%) and films (10.6%). According to our results, the low level of anthropogenic particles intake from the salts (maximum 37 particles per individual per annum) warrants negligible health impacts. However, to better understand the health risks associated with salt consumption, further development in extraction protocols are needed to isolate anthropogenic particles smaller than 149 μm

Wide bandwidth instantaneous radio frequency spectrum analyzer based on nitrogen vacancy centers in diamond

We propose an original analog method to perform instantaneous and quantitative spectral analysis of microwave signals. An ensemble of nitrogen-vacancy (NV) centers held in a diamond plate is pumped by a 532 nm laser. Its photoluminescence is imaged through an optical microscope and monitored by a digital camera. An incoming microwave signal is converted into a microwave field in the area of the NV centers by a loop shaped antenna. The resonances induced by the magnetic component of that field are detected through a decrease of the NV centers photoluminescence. A magnetic field gradient induces a Zeeman shift of the resonances and transforms the frequency information into spatial information, which allows for the simultaneous analysis of the microwave signal in the entire frequency bandwidth of the device. The time dependent spectral analysis of an amplitude modulated microwave signal is demonstrated over a bandwidth of 600 MHz, associated to a frequency resolution of 7MHz , and a refresh rate of 4 ms. With such integration time, a field of a few hundreds of lW can be detected. Since the optical properties of NV centers can be maintained even in high magnetic field, we estimate that an optimized device could allow frequency analysis in a range of 30 GHz, only limited by the amplitude of the magnetic field gradient. In addition, an increase of the NV centers quantity could lead both to an increase of the microwave sensitivity and to a decrease of the minimum refresh rate down to a few ls

Phase modulators ands splitting network on Si PIC coherent fiber beam combining

Coherent beam combining (CBC) of fiber lasers provide an attractive mean of reaching high output laser power by scaling up the available energy while keeping fiber intrinsic advantages of compactness, reliability, efficiency, and beam quality. In CBC architectures, the power of a master oscillator (MO) is divided into N fibers that are amplified individually. The phase perturbations between channels can be measured using various techniques [1-3] and are corrected by individual phase modulators placed on each fiber before the amplification. In this Communication, we present a Silicon PIC integrating a 1:16 channels splitting network and thermal phase modulators array with low electrical power consumption and a bandwidth compatible with CBC requirements. In our CBC system, a 1.55µm CW master oscillator directly feeds the Silicon chip through a grating coupler, as shown in Fig.1(a). The power of the master oscillator is first split on chip into 16 channels, each of which including a thermal phase modulator. The outputs of the 16 waveguides are collectively out-coupled from the chip using a PM optical fiber array aligned and glued onto the PIC’s output grating couplers array [4]. At the other end of fiber array, the 16 fiber outputs are arranged in a 4 by 4 squared lattice, and collimated by a microlens array to form 16 collimated and parallel beamlets. The phase distribution from channel to channel is derived from the fringe pattern resulting from the collimated beamlets interfering with a reference plane wave on a camera. This signal is fed back to drive the PIC’s phase modulators in order to phase lock the 16 fiber

Phase modulators and splitting network on Si PIC for coherent fiber beam combining

Coherent beam combining (CBC) of fiber lasers provide an attractive mean of reaching high output laser power by scaling up the available energy while keeping fiber intrinsic advantages of compactness, reliability, efficiency, and beam quality. In CBC architectures, the power of a master oscillator (MO) is divided into N fibers that are amplified individually. The phase perturbations between channels can be measured using various techniques [1-3] and are corrected by individual phase modulators placed on each fiber before the amplification. In this Communication, we present a Silicon PIC integrating a 1:16 channels splitting network and thermal phase modulators array with low electrical power consumption and a bandwidth compatible with CBC requirements

OPTICAL PUMPING OF 3He and 3He - 4He MIXTURES WITH A HIGH POWER INFRARED LMA LASER

No abstract availabl

Optical pumping of helium-3 with a frequency electromodulated laser

We have operated an electrooptical modulator to generate sidebands to the laser used for optical pumping of a helium-3 gas. Spreading the laser power over the Doppler absorption profile of the metastable helium atoms can enhance the efficiency of the optical pumping process. This improvement is discussed in terms of velocity changing collisions and compared to the result of a velocity selective optical pumping experiment.Nous avons ajouté des bandes latérales à la structure de modes du laser utilisé pour le pompage optique d'un gaz d'hélium-3 au moyen d'un modulateur électro-optique externe. Nous avons ainsi montré que l'efficacité du processus de pompage optique peut être améliorée par une meilleure répartition de la puissance du laser sur le profil d'absorption Doppler des atomes d'hélium. Cette amélioration peut être expliquée par l'effet des collisions purement élastiques dans le gaz. Cette interprétation est confirmée par le résultat d'une expérience de pompage optique sélectif en vitesse

Optical pumping of helium with arc lamp excited LNA lasers

We have developed a compact and relatively inexpensive laser source at λ =1.083 μm, suitable for optical pumping in helium. The laser is made of an LNA crystal transversely pumped by krypton arc lamps. A cw power of 800 mW has been achieved at 1.083 μm with a 3 GHz bandwidth. A 66 % nuclear polarization has been obtained in a 3He gas

A simple construction of very high order non oscillatory compact schemes on unstructured meshes.

In \cite{abgrall-roe} have been constructed very high order residual distribution schemes for scalar problems. They were using triangle unstructured meshes. However, the construction was quite involved and was not very flexible. Here, following \cite{abgrall}, we develop a systematic way of constructing very high order non oscillatory schemes for such meshes. Applications to scalar and systems problems are given