On the application of surface enhanced Raman scattering to study the interaction of DsRed fluorescent proteins with silver nanoparticles embedded in thin silica layers

The interaction of proteins with silver nanoparticles (AgNPs) is of primary importance to uncover silver antimicrobial efficiency and environmental hazard. This interaction can affect silver reactivity, bioavailability and, eventually, silver toxicity towards the environmental media. Detection of the interaction of DsRed fluorescent proteins with AgNPs embedded in thin silica layers is demonstrated using surface enhanced Raman spectroscopy (SERS), but deep analyses require the design and elaboration of dedicated plasmonic substrates giving a high enhancement factor

Honey, a Gift from Nature to Health and Beauty: A Review

Benefits of honey are contributed by the composition of its elements such as glucose, fructose, glucose oxidase, vitamins and phenolic compounds. For health, honey can be used to treat wounds due to the antibacterial activity conferred by the hydrogen peroxide produced by glucose oxidase in honey. Anti-inflammatory, anti-oxidant, deodorizing and tissue regeneration activities in honey also help in the wound healing process. It can also be an alternative sweetener for diabetic patients to ensure compliance to a healthy diet. Moreover, honey exerts several effects such as lowering low density lipids and increasing high density lipids, thus reducing risk of atherosclerosis. In terms of beauty, honey can be used on skin and hair. It moisturizes skin through its natural humectant properties contributed by high contents of fructose and glucose. Honey treats acne on the skin due to its antibacterial activity, anti-inflammatory action and tissue repair. The hair can benefit from honey in such a way that the hair has abundance, and becomes easier to comb. However, there have not been as many studies regarding the use of honey in skin in comparison to its use for health. Therefore, future studies on honey could research its use, action and benefits in both cosmetics and dermatology

Auger quenching-based modulation of electroluminescence from ion-implanted silicon nanocrystals

We describe high-speed control of light from silicon nanocrystals under electrical excitation. The nanocrystals are fabricated by the ion implantation of Si+ in the 15?nm thick gate oxide of a field effect transistor at 6.5?keV. A characteristic read-peaked electroluminescence is obtained either by DC or AC gate excitation. However, AC gate excitation is found to have a frequency response that is limited by the radiative lifetimes of silicon nanocrystals, which makes impossible the direct modulation of light beyond 100?kb?s?1 rates. As a solution, we demonstrate that combined DC gate excitation along with an AC channel hot electron injection of electrons into the nanocrystals may be used to obtain a 100% deep modulation at rates of 200?Mb?s?1 and low modulating voltages. This approach may find applications in biological sensing integrated into CMOS, single-photon emitters or direct encoding of information into light from Si-nc doped with erbium systems, which exhibit net optical gain. In this respect, the main advantage compared to conventional electro-optical modulators based on plasma dispersion effects is the low power consumption (104 times smaller) and thus the inherent large scale of integration. A detailed electrical characterization is also given. An Si/SiO2 barrier change from ?b = 3.2 to 4.2?eV is found while the injection mechanism is changed from Fowler?Nordheim to channel hot electron, which is a clear signature of nanocrystal charging and subsequent electroluminescence quenching

Direct modulation of electroluminescence from silicon nanocrystals beyond radiative recombination rates

We propose a light emitting transistor based on silicon nanocrystals provided with 200 Mbits/ s built-in modulation. Suppression of electroluminescence from silicon nanocrystals embedded into the gate oxide of a field effect transistor is achieved by fast Auger quenching. In this process, a modulating drain signal causes heating of carriers in the channel and facilitates the charge injection into the nanocrystals. This excess of charge enables fast nonradiative processes that are used to obtain 100% modulation depths at modulating voltages of 1 V

Post-annealed silicon nanocrystal formation on substoichiometric SiO

In this work is presented a detailed physicochemical, structural and optical characterization of SiOxNy thin films. The films deposited using PECVD in SiH4-N2O-He discharges were thermally annealed at 1273 K for 1 hour in ambient nitrogen. The film stochiometry was measured by Rutherford Backscattering Spectroscopy. The chemical composition was dominated by silicon suboxide containing some Si-N and Si-H bonds. Raman scattering measurements suggest the formation of nanocrystallite silicon in the annealed films. The Raman observation is strongly supported by Transmission Electron Microscopy analysis which shows a high density of silicon nanocrystals, having a mean radius ranging between 3 and 6 nm. Using Spectroscopic Ellipsometry, we discussed the dielectric function evolution as a function of the deposition parameters

Adsorption of proteins on solid surfaces containing AgNPs

International audienc

Structural and electrical characterization of Si nanocrystal memory devices created in stepwise process

International audienc

Advanced concept for fabrication of Si-nanocrystal memory devices through PPECVD followed by thermal oxidation

International audienc

Proposition d'une démarche simple pour évaluer la diversité floristique d'une prairie permanente

An easy method for the evaluation of a pasture's floristic diversity was developed in Auvergne, making it possible for a non-botanist to assess its bio-diversity. The aim was to make people working in the sphere of agriculture aware of the floristic diversity of ordinary grasslands. It relies on qualitative and quantitative observations made on pasture plots where different vegetation facies are distinguished. In our view, the floristic diversity of a pasture depends on the swards composition, but is also enhanced by the diversity of the landscape; we therefore assessed both these factors in our approach. The selection of indicators of the bio-diversity was based on the study of 126 vegetation facies, evenly distributed over four classes of pastures differing in their type of management (grazing or mowing) and in their environment (upland, lowland with a rich or a poor soil). We made for each facies both a botanical inventory and a simplified description of the vegetation, the fauna and the landscape features. To identify indicators, we looked for linear correlations between bio-diversity, as calculated from the inventories, and the data from the simplified descriptions. Nine indicators were found for the assessment of the herbaceous vegetation's diversity : total and average number of species with a different physiognomy, colours, forms of flowers... and one indicator was based on the diversity in butterflies. These indicators can be obtained on the field by a simplified counting, inside 10 circles of 1 m diameter for the flora, and along a transect for the fauna. They are more or less the same for each class, the main difference being in the identification thresholds, which are adapted to the Auvergne grasslands. The indicators of a given class were gathered in a single grid, in which five levels of bio-diversity were diagnosed. In addition to the assessment of each facies, we also propose a measure of the differences among the facies of the same plot. This point concerns only the number of species of different physiognomy. Separate grids were also designed for the assessment of the diversity of landscapes, as we did not find any correlation between the latter and the diversity of the herbaceous vegetation. Two indicators were used : the number and the types of landscape elements. The grids have also indication thresholds for each class and for the five levels of bio-diversity. Finally, various ways of interpreting the results are proposed to the users of the method, based on the hypothesis that the diversity depends not only on management and environment, but also on the landscapes. The way landscape diversity can increase and maintain the floristic diversity of grasslands is also emphasized.Peut-on évaluer la diversité floristique d’une prairie à partir d’observations simples sur le terrain ? L’élaboration d’une démarche de diagnostic adaptée à des non-spécialistes de la flore nécessite de clarifier les différentes composantes de la biodiversité d’une parcelle. La démarche de diagnostic de la diversité floristique proposée ici s’applique à l’échelle du faciès de végétation et distingue deux composantes : le fonds prairial et les éléments paysagers. Le diagnostic du fonds prairial, qui fait référence à une typologie régionale de la biodiversité, est basé sur des comptages simplifiés d’espèces, de couleurs et de formes de fleurs, sans reconnaissance botanique précise. Le diagnostic de la diversité paysagère utilise le nombre et les différents types d’éléments paysagers présents sur le faciès. Les deux diagnostics différencient chacun cinq niveaux de diversité et se déclinent pour quatre catégories de prairies auvergnates définies par leur usage et leur milieu physique. A l’issue des diagnostics, des pistes d’interprétation sont suggérées à l’utilisateur en considérant que la diversité floristique d’une prairie est fonction du milieu et des pratiques agricoles mais aussi de la diversité paysagère