Chemical Composition,Antioxidant and Anti-Inflammatory Activities of Clary Sage and Coriander Essential Oils Produced on Polluted and Amended Soils-Phytomanagement Approach

The potential of essential oils (EO), distilled from two aromatic plants—clary sage (Salvia sclarea L.) and coriander (Coriandrum sativum L.)—in view of applications as natural therapeutic agents was evaluated in vitro. These two were cultivated on a trace element (TE)-polluted soil, as part of a phytomanagement approach, with the addition of a mycorrhizal inoculant, evaluated for its contribution regarding plant establishment, growth, and biomass production. The evaluation of EO as an antioxidant and anti-inflammatory, with considerations regarding the potential influence of the TE-pollution and of the mycorrhizal inoculation on the EO chemical compositions, were the key focuses. Besides, to overcome EO bioavailability and target accession issues, the encapsulation of EO in β-cyclodextrin (β-CD) was also assessed. Firstly, clary sage EO was characterized by high proportions of linalyl acetate (51–63%) and linalool (10–17%), coriander seeds EO by a high proportion of linalool (75–83%) and lesser relative amounts of γ-terpinene (6–9%) and α-pinene (3–5%) and coriander aerial parts EO by 2-decenal (38–51%) and linalool (22–39%). EO chemical compositions were unaffected by both soil pollution and mycorrhizal inoculation. Of the three tested EO, the one from aerial parts of coriander displayed the most significant biological effects, especially regarding anti-inflammatory potential. Furthermore, all tested EO exerted promising antioxidant effects (IC₅₀ values ranging from 9 to 38 g L⁻¹). However, EO encapsulation in β-CD did not show a significant improvement of EO biological properties in these experimental conditions. These findings suggest that marginal lands polluted by TE could be used for the production of EO displaying faithful chemical compositions and valuable biological activities, with a non-food perspective.     

Nouveaux Élastomères de polyuréthanes dérivés d'aminoacides

Synthesis and characterization of new polyurethane elastomers with rigid blocks derived from aminoacids have been achieved by polycondensation using poly(tetramethylene oxide) (PTMO) as a soft segment. Aminotelechelic oligopeptides or pseudopeptides were used in the hard block, eventually in association with lysine diisocyanate (ethyl 2, 6-diisocyanatohexanoate, LDI). Physicochemical characteristics of the so obtained materials, especially good filmmaking properties, allow their use as biomaterials of reduced toxicity.     

Modeling the triggering of streamers in air by ultrashort laserpulses

The physical processes involved in the triggering of ionization waves (streamers) by ultrashort laser pulses, focused in air at 350 Torr and in a uniform electric field, are investigated by means of a one-dimensional (1-D) numerical model. The model describes the interaction of the laser pulse with air and takes into account many of the reactions in the laser-created plasma as well as the radial expansion of the plasma. Consequences of the model are that the threshold electric field for the appearance of streamers is an increasing function of the delay between the laser pulse and the electric field pulse and a decreasing function of the laser energy. Also, it appears that the electron temperature, the plasma density and radius, and the conduction of heat across the plasma boundaries play major roles in the capacity of the laser-created plasma to trigger streamers. The results of the model are compared with the available experimental data     

XPS study of the O2/SF6 microwave plasma oxidation of (0 0 1) GaAs surfaces

O₂SF₆ plasma effects on processed GaAs surfaces have been investigated. The influence of plasma parameters such as composition, power and exposure time has been studied. The microwave plasma treatment efficiency has been studied by surface depth profiling (cycles consisting of XPS measurements followed by a slight etching) coupled with an original modelling calculation. We have pointed out that SF₆ addition in plasma increases the oxidative rule of oxygen by increasing the total oxide thickness and that the quantity of the different oxidative and passivating species does not limit the oxidative mechanism, in the O₂:SF₆ ratio range 80:20 to 40:60. The increase in the plasma power leads to a change in the composition of the outer region of the oxide layer with an increase in the gallium content on the surface, and to an increase in the total oxide layer. The exposure time to the plasma increases also these two phenomena.     

Oxygen concentration and modeling thermal decomposition of a high‐performance material: A case study of polyimide (Cirlex)

Kinetic decomposition models for the thermal decomposition of a high‐performance polymeric material (Polyimide, PI) were determined from specific techniques. Experimental data from thermogravimetric analysis (TGA) and previously elucidated decomposition mechanism were combined with numerical simulating tool to establish a comprehensive kinetic model for the decomposition of PI under three atmospheres: nitrogen, 2% oxygen, and synthetic air. Multistaged kinetic models with subsequent and competitive reactions were established by taking into consideration the different types of reactions that may be occurring during the thermal decomposition of the material (chain scission, thermo‐oxidation, char formation). The decomposition products and decomposition mechanism of PI which was established in our previous report allowed for the elucidation of the kinetic decomposition models. A three‐staged kinetic thermal decomposition pathway was a good fit to model the thermal decomposition of PI under nitrogen. The kinetic model involved an autocatalytic type of reaction followed by successive nth order reactions. Such types of models were set up for the evaluation of the kinetics of the thermal decomposition of PI under 2% oxygen and in air, leading to models with satisfactory fidelity.     

Polyvalent Transition-State Analogues of Sialyl Substrates Strongly Inhibit Bacterial Sialidases**

Bacterial sialidases (SA) are validated drug targets expressed by common human pathogens such as Streptococcus pneumoniae, Vibrio cholerae, or Clostridium perfringens. Noncovalent inhibitors of bacterial SA capable of reaching the submicromolar level are rarely reported. In this work, multi- and polyvalent compounds are developed, based on the transition-state analogue 2-deoxy-2,3-didehydro-N-acetylneuraminic (DANA). Poly-DANA inhibits the catalytic activity of SA from S. pneumoniae (NanA) and the symbiotic microorganism B. thetaiotaomicron (BtSA) at the picomolar and low nanomolar levels (expressed in moles of molecules and of DANA, respectively). Each DANA grafted to the polymer surpasses the inhibitory potential of the monovalent analogue by more than four orders of magnitude, which represents the highest multivalent effect reported so far for an enzyme inhibition. The synergistic interaction is shown to operate exclusively in the catalytic domain, and not in the flanked carbohydrate-binding module (CBM). These results offer interesting perspectives for the multivalent inhibition of other SA families lacking a CBM, such as viral, parasitic, or human SA.     

Management of the electrical injection uniformity in broad-area top-emitting VCSELs

The electrical properties of broad-area 850 nm top emitting VCSELs have been investigated in order to improve carrier injection uniformity in their active zone. First, we have demonstrated using an electrical simulation tool that a multi-point localized injection design associated with a spreading layer at the top of the device (ITO) can lead to a significant improvement of carrier injection and on its spatial distribution. Secondly, the electrical contrast achievable by applying this method with localized etchings has been experimentally measured. Finally, stripe-shaped devices with output power up to 50 mW in a continuous-wave operation at room temperature have been demonstrated.     

Towards athermal optically-interconnected computing system using slotted silicon microring resonators and RF-photonic comb generation

We report that completely athermal design of a slotted silicon waveguide is possible by combining the negative thermo-optic (TO) coefficient of, for example, polymethyl methacrylate (PMMA) with the positive TO coefficient of silicon. When used in a microring resonator structure, the filled overcladding slotted waveguide and the unfilled (air-filled) overcladding slotted waveguide can both achieve athermal characteristics. Simulations indicate a wide range of realizations with proper design parameters of the slotted waveguides, namely, the silicon strip and slot widths. Preliminary experimental results on fabricated devices demonstrate that the temperature dependence is reduced from 91 pm/°C for a regular microring resonator to 52 pm/°C for the PMMA-clad microring resonator. Completely athermal realization is expectable in similar devices with improved fabrication techniques. For the external optical source, we demonstrate a stable 3.5 THz wide (175 modes×20 GHz) optical comb source with nearly flat spectral phase. Adjustable mode spacing and wavelength tunability across the C-band are maintained so that comb lines can be matched to the specified wavelength grid of the computing system. With such schemes, temperature controls of individual optical components in the optically interconnected computing chips become unnecessary, greatly reducing the complexity of the computing system.     

Nonlinear friction dynamics on fibrous materials,application to the characterization of surface quality. Part I: global characterization of phase spaces

The diversity and the complexity of fibrous materials (woven fabrics, nonwovens or knitted fabrics) make the control of surface qualities very difficult. The control and the comprehension of the tribological phenomena generated by a dynamic friction are of major importance. Whereas the traditional investigations such as measurements of average parameters like roughness or friction coefficient quickly find their limits on such deformable, heterogeneous and flexible fibrous surfaces with very heterogeneous relief, this series of two publications proposes a new manner of observing the interactions of friction. Our laboratory has developed a patented method of measurements, called MODALSENS, which aims at rubbing a very fine and flexible blade on the analyzed surface. Dynamic friction with the contact generates nonlinear vibrations, and the response of the sensor is analyzed in its phase space using the tools of nonlinear analysis of time series. Then, when the evaluated surfaces change, this first part endeavors to characterize the portraits of phases related to the nonlinear vibrations of MODALSENS in a global way, by quantifying its invariants such as dimensions, Shannon entropies, diameters of attractors and largest Lyapunov exponents. From this first part, a classification of studied fibrous surfaces is built and is expected to give rise to new estimators for the surface quality analysis of fibrous media.