Chapter From Cellulose Dissolution and Regeneration to Added Value Applications — Synergism Between Molecular Understanding and Material Development

Laser ablation (LA) and spark discharge (SD) techniques are commonly used for nanoparticle (NP) formation. The produced NPs have found numerous applications in such areas as electronics, biomedicine, textile production, etc. Previous studies provide us information about the amount of NPs, their size distribution, and possible applications. On one hand, the main advantage of the LA method is in the possibilities of changing laser parameters and background conditions and to ablate materials with complicated stoichiometry. On the other hand, the major advantage of the SD technique is in the possibility of using several facilities in parallel to increase the yield of nanoparticles. To optimize these processes, we consider different stages involved and analyze the resulting plasma and nanoparticle (NP) parameters. Based on the performed calculations, we analyze nanoparticle properties, such as mean size and mean density. The performed analysis (shows how the experimental conditions are connected with the resulted nanoparticle characteristics in agreement with several previous experiments. Cylindrical plasma column expansion and return are shown to govern primary nanoparticle formation in spark discharge, whereas hemispherical shock describes quite well this process for nanosecond laser ablation at atmospheric pressure. In addition, spark discharge leads to the oscillations in plasma properties, whereas monotonous behavior is characteristic for nanosecond laser ablation. Despite the difference in plasma density and time evolutions calculated for both phenomena, after well-defined delays, similar critical nuclei have been shown to be formed by both techniques. This result is attributed to the fact that whereas larger evaporation rate is typical for nanosecond laser ablation, a mixture of vapor and background gas determines the supersaturation in the case of spark

Size, shape, orientation and crystallinity of cellulose Iβ by X-ray powder diffraction using a free spreadsheet program

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Growth of Clathrate Hydrates from Water Drops in Cyclopentane

International audienceClathrate hydrates are icelike crystalline compounds with encaged guest molecules trapped inside the cages of hydrogen bonded water molecules. Their growth is visualized for cyclopentane within water drops of two microliters on glass and poly-tetrafluoroethylene surfaces. The effect of the interfacial tension between water and cyclopentane is measured at different temperatures and for different concentration of an oil-soluble surfactant: sorbitan monooleate (Span 80). The drops experience a temperature sequence where they freeze into ice, form hydrates and melt. Cyclopentane hydrates crystals are affected by the concentration of surfactant. The morphology seen here could be relevant for explaining the behavior of hydrate emulsions

Green ionic liquids for the production of fully-biobased and biodegradable all-cellulose nanocomposites

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Article Combining Satellite Remote Sensing Data with the FAO-56 Dual Approach for Water Use Mapping In Irrigated Wheat Fields of a Semi-Arid Region

Abstract: The aim of this study was to combine the FAO-56 dual approach and remotely-sensed data for mapping water use (ETc) in irrigated wheat crops of a semi-arid region. The method is based on the relationships established between Normalized Difference Vegetation Index (NDVI) and crop biophysical variables such as basal crop coefficient, cover fraction and soil evaporation. A time series of high spatial resolution SPOT and Landsat images acquired during the 2002/2003 agricultural season has been used to generate the profiles of NDVI in each pixel that have been related to crop biophysical parameters which were used in conjunction with FAO-56 dual source approach. The obtained results showed that the spatial distribution of seasonal ETc varied between 200 and 450 mm depending to sowing date and the development of the vegetation. The validation of spatial results showed that the ETc estimated by FAO-56 corresponded well with actual ET measured by eddy covariance system over test sites of wheat, especially when soil evaporation and plant water stress are not encountered. Remote Sens. 2010, 2 37

Evidences of low land surface thermal infrared emissivity in presence of dry 21

Abstract—Land surface emissivity in the thermal infrared usually increases when the vegetation amount increases, reaching values that are larger than 0.98. During an experiment in Morocco over dry barley crops, it was found that emissivity may be significantly lower than 0.98 at full cover and that in some situations, it might decrease with increasing amount of vegetation, which was unexpected. Older data acquired in Barrax, Spain, over senescent barley also exhibited emissivity values lower than 0.98. The decrease of emissivity was also observed by means of simulations done with our land surface emissivity model developed earlier. The main reason for such behavior might be found in low leaf emissivity due to leaf dryness. This letter also stresses that knowledge on leaf and canopy emissivities and on their variation as a function of water content is still very limited. Index Terms—Barley, emissivity, normalized difference vegetation index (NDVI), plant canopy, thermal infrared, wheat. I

3D analysis from micro-MRI during in situ compression on cancellous bone.

The authors would like to acknowledge Claude Verliac and Joachim Magnier for technical advice on the manufacturing process of the mechanical loading system.A mini-compression jig was built to perform in situ tests on bovine trabecular bone monitored by micro-MRI. The MRI antenna provided an isotropic resolution of 78 microm that allows for a volume correlation method to be used. Three-dimensional displacement fields are then evaluated within the bone sample during the compression test. The performances of the correlation method are evaluated and discussed to validate the technique on trabecular bone. By considering correlation residuals and estimates of acquisition noise, the measured results are shown to be trustworthy. By analyzing average strain levels for different interrogation volumes along the loading direction, it is shown that the sample size is less than that of a representative volume element. This study shows the feasibility of the 3D-displacement and strain field analyses from micro-MRI images. Other biological tissues could be considered in future work

Self-Supervised Sidewalk Perception Using Fast Video Semantic Segmentation for Robotic Wheelchairs in Smart Mobility

International audienceThe real-time segmentation of sidewalk environments is critical to achieving autonomous navigation for robotic wheelchairs in urban territories. A robust and real-time video semantic segmentation offers an apt solution for advanced visual perception in such complex domains. The key to this proposition is to have a method with lightweight flow estimations and reliable feature extractions. We address this by selecting an approach based on recent trends in video segmentation. Although these approaches demonstrate efficient and cost-effective segmentation performance in cross-domain implementations, they require additional procedures to put their striking characteristics into practical use. We use our method for developing a visual perception technique to perform in urban sidewalk environments for the robotic wheelchair. We generate a collection of synthetic scenes in a blending target distribution to train and validate our approach. Experimental results show that our method improves prediction accuracy on our benchmark with tolerable loss of speed and without additional overhead. Overall, our technique serves as a reference to transfer and develop perception algorithms for any cross-domain visual perception applications with less downtime

Grafting amount and structural characteristics of microcrystalline cellulose functionalized with diferent aminosilane contents

Microcrystalline cellulose (MCC) has unique properties and its use as reinforcement for polymer composites has been increasing. However, the intrinsic incompatibility with most polymers requires surface modification to improve chemical compatibility prior to its incorporation into a polymer. In this paper, a grafting amount and structural characteristics of MCC functionalized with 3-aminopropyltriethoxysilane (APTES) (MCC-Si) at different contents was performed. We reported a comparison of three different methods for quantifying the APTES grafting amount: from TGA curves, nitrogen content, and silicon content. Supplementary analyses were performed: solid-state 13 C and 29Si nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy with energy dispersive X-ray (SEM-EDX). A deep study of structural properties by X-ray diffraction was also conducted. A better correlation for grafting amount of APTES onto MCC was observed for nitrogen content method than residual mass according to the Pearson’s correlation. 13 C NMR revealed all the carbon structures from cellulose and side bands for MCC-Si samples and from APTES molecules and 29Si NMR revealed T structures. The silane treatment did not alter the shape of MCC and all treated samples showed Si characteristic peak at ~ 1.75 kEv. The exposure to APTES in an acidic medium caused several effects on the MCC, splitting larger Iβ crystallites in half and along the more reactive hydrophilic sides. The diameter of the smaller IVI crystallites was largely reduced by the treatment, especially when the silane concentration was 1:5 (m/v), above which the diameter increases again