2D reproduction of the face on the Turin Shroud by infrared femtosecond pulse laser processing.

Femtosecond pulse laser processing concentrates a huge quantity of light energy in extremely short pulses of a few tens to hundreds of femtoseconds, enabling superficial laser machining or marking of any kind of materials, with a reduced or insignificant heat affected area. A digitized paper printed image of the face on the Turin Shroud was used to monitor a scan head intercalated between a femtosecond pulsed laser source and a linen fabric sample, enabling the direct 2D reproduction of the image of the face with a laser beam size corresponding to one pixel of the digitized image. The contrast in the marked image was controlled by adjusting the energy density, the number of superimposed pulses per pixel, and the distance between successive impacts. The visual aspect of the laser-induced image is very similar, at naked eye, to the source image. The negative photograph of the marked linen fabric reveals a face remarkably close to the well-known negative picture of the face on the Turin Shroud. Analyses by infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy were performed to characterize the laser marked areas.

Exploring gravity with the MIGA large scale atom interferometer.

We present the MIGA experiment, an underground long baseline atom interferometer to study gravity at large scale. The hybrid atom-laser antenna will use several atom interferometers simultaneously interrogated by the resonant mode of an optical cavity. The instrument will be a demonstrator for gravitational wave detection in a frequency band (100 mHz-1 Hz) not explored by classical ground and space-based observatories, and interesting for potential astrophysical sources. In the initial instrument configuration, standard atom interferometry techniques will be adopted, which will bring to a peak strain sensitivity of [Formula: see text] at 2 Hz. This demonstrator will enable to study the techniques to push further the sensitivity for the future development of gravitational wave detectors based on large scale atom interferometers. The experiment will be realized at the underground facility of the Laboratoire Souterrain à Bas Bruit (LSBB) in Rustrel-France, an exceptional site located away from major anthropogenic disturbances and showing very low background noise. In the following, we present the measurement principle of an in-cavity atom interferometer, derive the method for Gravitational Wave signal extraction from the antenna and determine the expected strain sensitivity. We then detail the functioning of the different systems of the antenna and describe the properties of the installation site.

The method of UCN "small heating" measurement in the big gravitational spectrometer (BGS) and studies of this effect on Fomblin oil Y-HVAC 18/8.

The Big Gravitational Spectrometer (BGS) takes advantage of the strong influence of the Earth's gravity on the motion of ultracold neutrons (UCNs) that makes it possible to shape and measure UCN spectra. We optimized the BGS to investigate the "small heating" of UCNs, that is, the inelastic reflection of UCNs from a surface accompanied by an energy change comparable with the initial UCN energy. UCNs whose energy increases are referred to as "Vaporized UCNs" (VUCNs). The BGS provides the narrowest UCN spectra of a few cm and the broadest "visible" VUCN energy range of up to ∼150 cm (UCN energy is given in units of its maximum height in the Earth's gravitational field, where 1.00 cm ≈ 1.02 neV). The dead-zone between the UCN and VUCN spectra is the narrowest ever achieved (a few cm). We performed measurements with and without samples without breaking vacuum. BGS provides the broadest range of temperatures (77-600 K) and the highest sensitivity to the small heating effect, up to ∼10-8 per bounce, i.e., two orders of magnitude higher than the sensitivity of alternative methods. We describe the method to measure the probability of UCN "small heating" using the BGS and illustrate it with a study of samples of the hydrogen-free oil Fomblin Y-HVAC 18/8. The data obtained are well reproducible, do not depend on sample thickness, and do not evolve over time. The measured model-independent probability P+ of UCN small heating from an energy "mono-line" 30.2 ± 2.5 cm to the energy range 35-140 cm is in the range 1.05±0.02stat×10-5-1.31±0.24stat×10-5 at a temperature of 24 °C. The associated systematic uncertainty would disappear if a VUCN spectrum shape were known, for instance, from a particular model of small heating. This experiment provides the most precise and reliable value of small heating probability on Fomblin measured so far. These results are of importance for studies of UCN small heating as well as for analyzing and designing neutron lifetime experiments.

Polarization-driven self-organization of silver nanoparticles in 1D and 2D subwavelength gratings for plasmonic photocatalysis.

One of the main challenges in plasmonics is to conceive large-scale, low-cost techniques suitable for the fabrication of metal nanoparticle patterns showing precise spatial organization. Here, we introduce a simple method based on continuous-wave laser illumination to induce the self-organization of silver nanoparticles within high-index thin films. We show that highly regular and homogeneous nanoparticle gratings can be produced on large areas using laser-controlled self-organization processes. This very versatile technique can provide 1D and 2D patterns at a subwavelength scale with tunable features. It does not need any stabilization or expensive devices, such as those required by optical or electron lithography, and is rapid to implement. Accurate in-plane and in-depth characterizations provide valuable information to explain the mechanisms that lead to pattern formation and especially how 2D self-organization can fall into place with successive laser scans. The regular and homogeneous 2D self-organization of metallic NPs with a single laser scan is also reported for the first time in this article. As the reported nanostructures are embedded in porous TiO2, we also theoretically explore the interesting potential of organization on the photocatalytic activity of Ag-NP-containing TiO2 porous films, which is one of the most promising materials for self-cleaning or remediation applications. Realistic electromagnetic simulations demonstrate that the periodic organization of silver nanoparticles can increase the light intensity within the film more than ten times that produced with randomly distributed nanoparticles, leading as expected to enhanced photocatalytic efficiency.

Reply to "Comment on 'Lifshitz-Matsubara sum formula for the Casimir pressure between magnetic metallic mirrors' ".

We reply to the "Comment on 'Lifshitz-Matsubara sum formula for the Casimir pressure between magnetic metallic mirrors.' " We believe the comment misrepresents our papers, and fails to provide a plausible resolution to the conflict between theory and experiment.

Lifshitz-Matsubara sum formula for the Casimir pressure between magnetic metallic mirrors.

We examine the conditions of validity for the Lifshitz-Matsubara sum formula for the Casimir pressure between magnetic metallic plane mirrors. As in the previously studied case of nonmagnetic materials [Guérout et al., Phys. Rev. E 90, 042125 (2014)], we recover the usual expression for the lossy model of optical response, but not for the lossless plasma model. We also show that the modes associated with the Foucault currents play a crucial role in the limit of vanishing losses, in contrast to expectations.

Growth of single gold nanofilaments at the apex of conductive atomic force microscope tips.

This paper describes a fast and one-step technique to grow single gold filaments at the apex of commercial conductive AFM tips. It is implemented with an atomic force microscope in air with a high relative humidity at room temperature and is based on a bias-assisted electro-reduction of gold ions directly at the tip apex. The technique requires only ad hoc substrates made of a mesoporous silica layer loaded with gold salt deposited on a conductive electrode. It leads to the growth, at the tip apex, of filaments whose length can be monitored and controlled during the growth between tens and hundreds of nanometers and whose radius of curvature can be as low as 3 nm. Made of polycrystalline gold nanostructures, the filaments are chemically and mechanically stable and conductive.

First Evidence of an Important Organic Matter Trophic Pathway between Temperate Corals and Pelagic Microbial Communities.

Mucus, i.e., particulate and dissolved organic matter (POM, DOM) released by corals, acts as an important energy carrier in tropical ecosystems, but little is known on its ecological role in temperate environments. This study assessed POM and DOM production by the temperate coral Cladocora caespitosa under different environmental conditions. The subsequent enzymatic degradation, growth of prokaryotes and virus-like particles (VLPs) as well as changes in the structure of the prokaryotic communities were also monitored. C. caespitosa produced an important quantity of mucus, which varied according to the environmental conditions (from 37.8 to 67.75 nmol carbon h-1 cm-2), but remained higher or comparable to productions observed in tropical corals. It has an important nutritional value, as highlighted by the high content in dissolved nitrogen (50% to 90% of the organic matter released). Organic matter was rapidly degraded by prokaryotes' enzymatic activities, and due to its nitrogen content, aminopeptidase activity was 500 fold higher than the α-glucosidase activity. Prokaryotes, as well as VLPs, presented a rapid growth in the mucus, with prokaryote production rates as high as 0.31 µg h-1 L-1. Changes in bacterial and archaeal communities were observed in the ageing mucus and between mucus and the water column, suggesting a clear impact of mucus on microorganism diversity. Overall, our results show that the organic matter released by temperate corals, such as C. caespitosa, which can form reef structures in the Mediterranean Sea, stimulates microbial activity and thereby functions as a significant carbon and nitrogen supplier to the microbial loop.

Development of a new passive sampler based on diffusive milligel beads for copper analysis in water.

A new passive sampler was designed and characterized for the determination of free copper ion (Cu(2+)) concentration in aqueous solution. Each sampling device was composed of a set of about 30 diffusive milligel (DMG) beads. Milligel beads with incorporated cation exchange resin (Chelex) particles were synthetized using an adapted droplet-based millifluidic process. Beads were assumed to be prolate spheroids, with a diameter of 1.6 mm and an anisotropic factor of 1.4. The milligel was controlled in chemical composition of hydrogel (monomer, cross-linker, initiator and Chelex concentration) and characterized in pore size. Two types of sampling devices were developed containing 7.5% and 15% of Chelex, respectively, and 6 nm pore size. The kinetic curves obtained demonstrated the accumulation of copper in the DMG according to the process described in the literature as absorption (and/or adsorption) and release following the Fick's first law of diffusion. For their use in water monitoring, the typical physico-chemical characteristics of the samplers, i.e. the mass-transfer coefficient (k0) and the sampler-water partition coefficient (Ksw), were determined based on a static exposure design. In order to determine the copper concentration in the samplers after their exposure, a method using DMG bead digestion combined to Inductively Coupled Plasma - Atomic Emission Spectrometry (ICP-AES) analysis was developed and optimized. The DMG devices proved to be capable to absorb free copper ions from an aqueous solution, which could be accurately quantified with a mean recovery of 99% and a repeatability of 7% (mean relative uncertainty).

Large Area Fabrication of Periodic TiO2 Nanopillars Using Microsphere Photolithography on a Photopatternable Sol-Gel Film.

The authors demonstrate a unique low cost process to print 2D, submicron size, and high refractive index nanopillars using a direct colloidal-photolithography process. A well collimated i-line source emitting at 365 nm wavelength illuminates a mono layer of silica microspheres of 1 µm diameter deposited on a photosensitive TiO2-based sol-gel layer. No etching process is needed since this layer is directly UV photo patternable like a negative photoresist. Furthermore, this thin layer offers interesting optical properties (high refractive index and optical transparency) and good mechanical and chemical stability and thus can be directly used as a functional microstructure (for PV or sensor applications, for example). The paper describes the modeling of the electric field distribution below the spheres during the illumination process, the photochemistry of the TiO2 sol-gel layer process, and preliminary results of TiO2 nanopillars of around 200 nm in diameter fabricated on a three-inch substrate.

Photophysiology and daily primary production of a temperate symbiotic gorgonian.

Gorgonians are one of the most important benthic components of tropical and temperate areas, and play a fundamental role as ecosystem engineers. Although global warming and pollution increasingly threaten them, the acquisition of nutrients, which is a key process in fitness and stress resistance, has been poorly investigated in such species. This study has thus used an advanced in situ incubation chamber for the first time with gorgonians, to assess the daily acquisition of nutrients and the photophysiology of the Mediterranean symbiotic species, Eunicella singularis. The xanthophyll cycle was assessed in parallel. This work has revealed that E. singularis presents a different functioning than the Mediterranean symbiotic corals. This gorgonian indeed relies on both autotrophy and heterotrophy in summer to optimize its energetic budget, while corals mainly shift to autotrophy for their respiratory needs and tissue growth. In addition, although E. singularis lives in the same depths/locations, and harbours the same symbiont genotype than the corals, the photosynthetic performances of their respective symbionts are significantly different. Indeed, E. singularis acquired 2-3 times less autotrophic carbon from its symbionts than corals, but maintained a positive carbon budget by reducing respiration rates, and by presenting maximal photosynthetic rates throughout the day, suggesting a very efficient light utilization. Almost no photoinhibition was observed under very high light levels, because of the induction of a xanthophyll photoprotection process. These results help understanding why gorgonians often dominate many benthic ecosystems.

Amphiphilic derivatives of chitosan using microwave irradiation. Toward an eco-friendly process to chitosan derivatives.

Conventional heating and microwave irradiation have been compared for the synthesis of chitosans grafted with alkyl chains. Reaction time (1-60 min), temperature (25 and 40 °C) and chitosan molar mass have been studied onto the yield of alkylation. The irradiation mode has been scrupulously controlled to highlight the effect of the use of microwaves. The chemical structure of modified polymers (degree of alkylation) is determined from NMR. In relation to the rheological behavior and surface tension measurements, the evolution of hydrophobic interactions is studied as a function of the yield of alkylation. A maximum of intrinsic viscosity and hydrodynamic diameter was observed for a degree of alkylation of around 10%. All the results tend to prove that microwave assisted synthesis is a powerful method to obtain modified chitosan under extremely low reaction time without any degradation and/or property modifications.

Derivation of the Lifshitz-Matsubara sum formula for the Casimir pressure between metallic plane mirrors.

We carefully reexamine the conditions of validity for the consistent derivation of the Lifshitz-Matsubara sum formula for the Casimir pressure between metallic plane mirrors. We recover the usual expression for the lossy Drude model but not for the lossless plasma model. We give an interpretation of this new result in terms of the modes associated with the Foucault currents, which play a role in the limit of vanishing losses, in contrast to common expectations.

Saponins: a renewable and biodegradable surfactant from its microwave-assisted extraction to the synthesis of monodisperse lattices.

Synthetic surfactants are widely used in emulsion polymerization, but it is increasingly desirable to replace them with naturally derived molecules with a reduced environmental burden. This study demonstrates the use of saponins as biodegradable and renewable surfactants for emulsion polymerization. This chemical has been extracted from soapnuts by microwave assisted extraction and characterized in terms of surfactant properties prior to emulsion polymerization. The results in terms of particle size distribution and morphology control have been compared to those obtained with classical nonionic (NP40) or anionic (SDS) industrial surfactants. Microwave-extracted saponins were able to lead to latexes as stable as standard PS latex, as shown by the CMC and CCC measurements. The saponin-stabilized PS particles have been characterized in terms of particle size and distribution by Dynamic Light Scattering and Asymmetrical Flow Field Flow Fractionation. Monomodal and monodispersed particles ranging from 250 to 480 nm in terms of diameter with a particle size distribution below 1.03 have been synthesized.

Subwavelength cylindrical grating by holistic phase-mask coordinate transform.

A periodic grating with an integer number of periods is fabricated at the resist-coated wall of a cylinder by exposing a circularly symmetrical planar high index phase mask to a cylindrical wave. This extends the spatial coherence features easily achievable in a planar 2D space to the 3D space of cylindrical waves and elements.

Evidence of surface plasmon resonance in ultrafast laser-induced ripples.

The sensitivity of grating-coupled Surface Plasmon Polaritons (SPPs) on metallic surface has been exploited to investigate the correlation between ripples formation under ultrashort laser exposure and SPPs generation conditions. Systematic examination of coupling of single ultrashort laser pulse on gratings with appropriate periods ranging from 440 nm to 800 nm has been performed. Our approach reveals that a surface plasmon is excited only for an appropriate grating period, the nickel sample exhibits fine ripples pattern, evidencing the plasmonic nature of ripples generation. We propose a systematic investigation supported by a comprehensive study on the obtained modulation of such a coupling efficiency by means of a phenomenological Drude-Lorentz model which captures possible optical properties modification under femtosecond irradiation.

Chitosan-graft-polyaniline-based hydrogels: elaboration and properties.

Intrinsically conducting polymers are of great interest for a large number of applications. But among the major drawbacks are their low solubility in common solvents and their poor mechanical properties. Elaboration of composites associating a matrix, bringing its mechanical properties, and polyaniline, as the conducting polymer, is a way of overcoming these disadvantages. Chitosan-graft-polyaniline copolymers were synthesized by simple oxidative method. The grafting reaction was quite complete, and it was found that the copolymers cross-linked to yield a composite hydrogel in which the polyaniline was homogeneously embedded. The conductivity of precursor (block copolymer) and gels was found to be larger than 10(-2) S x cm(-1). The composite gels were characterized in terms of swelling and rheological properties. They can be classified as "superabsorbent" hydrogels, and the swelling is reversible. The composite gels were then successfully used as actuators.

Transcription profiling of eleven cytochrome P450s potentially involved in xenobiotic metabolism in the mosquito Aedes aegypti.

Transcription profiles of 11 Aedes aegypti P450 genes from CYP6 and CYP9 subfamilies potentially involved in xenobiotic metabolism were investigated. Many genes were preferentially transcribed in tissues classically involved in xenobiotic metabolism including midgut and Malpighian tubules. Life-stage transcription profiling revealed important variations amongst larvae, pupae, and adult males and females. Exposure of mosquito larvae to sub-lethal doses of three xenobiotics induced the transcription of several genes with an induction peak after 48 to 72 h exposure. Several CYP genes were also induced by oxidative stress and one gene strongly responded to 20-hydroxyecdysone. Overall, this study revealed that these P450s show different transcription profiles according to xenobiotic exposures, life stages or sex. Their putative chemoprotective functions are discussed.

Disorder in quantum vacuum: Casimir-induced localization of matter waves.

Disordered geometrical boundaries such as rough surfaces induce important modifications to the mode spectrum of the electromagnetic quantum vacuum. In analogy to Anderson localization of waves induced by a random potential, here we show that the Casimir-Polder interaction between a cold atomic sample and a rough surface also produces localization phenomena. These effects, that represent a macroscopic manifestation of disorder in quantum vacuum, should be observable with Bose-Einstein condensates expanding in proximity of rough surfaces.