Nitrocellulose | EPFL Graph Search

La nitrocellulose ou nitrate de cellulose est un ester de cellulose, explosif, dérivé de la cellulose. Il fut utilisé dans les munitions sous forme de fulmicoton, coton-poudre ou encore pyroxyle. Propriétés thumb|left|Inflammation de nitrocellulose (risque de brûlures) vignette|Nitrocellulose à l'état solide La nitrocellulose est à l'état sec un explosif fulminant, c'est-à-dire qu'il dégage de grandes quantités de gaz et de chaleur lors de sa combustion. La nitrocellulose peut se gélifier dans un mélange d'éther et d'alcool (selon le procédé de Paul Vieille). Le gel de nitrocellulose est appelé collodion. Ce produit est très peu soluble et semble très peu biodégradable dans l'eau. Historique thumb|left|250px|Obus Shrapnell allemand, avec douille (étui) chargé de cordons de nitrocellulose thumb|left|Charge ou "cartouche" de cordite (Cartridge 63½ lb (¼ charge) pour canon de marine (BL 12 inch Mk IX naval guns) des cuirassés de classe King Edward VII. La nitroc

Novel Analytical Methods for Allergy-Related Studies

Mikaël Frossard

Managing and treating diseases require a deep understanding of the pathologies coupled with accurate diagnostic procedures. The constant development and improvement of bioanalytical methods reflect the need of diagnosis ameliorations with respect to accuracy, sensitivity and efficiency. The field of allergy diagnosis is a good example. Despite affecting almost a third of the population in western countries, allergies still present complex challenges for the physicians in terms of diagnosis and allergen characterization. This thesis presents novel analytical methods developed for the fast and personalized allergy component-resolved diagnosis (CRD), the allergen identification and quantification in food matrices and the characterization of allergen modifications, notably nitration. Immunomagnetic separation (IMS) was used to perform the allergy diagnosis at the molecular level by extracting the IgE antibodies from allergic patient blood sera and probing them against individual allergens and natural allergenic extracts. The fast and highly selective IMS procedure was coupled to matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) mass spectrometry (MS) to identify accurately and with high sensitivity the proteins recognized as sensitizers by the patient antibodies. The developed CRD methods were successful to diagnose cowâs milk, egg, peanut and tree nuts allergies, allowing the resolution of several complex clinical cases. Additionally, precious information was collected for the cross-reactivity and cross-sensitization in peanut and tree nuts allergies using blood sera from the PronNut clinical study. Allergen nitration is one of the potential causes for the increase in allergy prevalence observed recently and requires thorough investigation. Herein, various nitrating agents were tested and compared for in vitro allergen nitration. After modifying allergens using two of the most efficient nitrating procedures, the nitration sites were identified by bottom-up proteomics (BUP) and compared to the known epitopes, bringing useful information and novel insights to the problem of correlation between protein nitration and allergenicity. The presence of a minute amount of allergens in a food product is responsible for potential life-threatening reactions in highly allergic patients and sensitive analytical methods are therefore required in food quality assessments. A proteomic-based method was used for the quality control of several food products suspected of causing severe reactions for peanut and hazelnut-allergic patients. Peptide markers were identified in a first screening of the food extracts by BUP using a high-resolution MS instrument. A standard addition method was then used to quantify peanut and hazelnut proteins by BUP using an untargeted âshotgunâ approach.

EPFL2020

Surface modified microfibrillated cellulose‐poly(vinylidene fluoride) composites: β‐phase formation, viscoelastic and dielectric performance

Dragan Damjanovic, Yves Leterrier, Véronique Michaud, Mohammed Arif Poothanari

The effect of silylation of microfibrillated cellulose (MFC) surfaces on β‐phase formation in poly(vinylidene difluoride) (PVDF) and the resulting viscoelastic and dielectric performance of MFC‐PVDF composites is investigated. Two different organosilanes, namely aminated (A) and fluorinated (F), were used. Composites of PVDF and MFC at concentrations up to 10 wt%, both untreated and silylated, were prepared by solvent casting. The two different surface modifications did not markedly change the melting and crystallization enthalpy of the polymer. However, only A‐MFC was found to promote β‐phase compared to the untreated MFC and the F‐MFC, which was attributed to the formation of hydrogen bonds at the interface between the amine groups of A‐MFC and the fluorine groups of PVDF. The elastic modulus and the permittivity of all composites increased with the amount of MFC up to a maximum value, depending on the MFC modification, and then decreased. This effect was due to the formation of MFC aggregates and porosity, as further confirmed by a comparison of experimental moduli with a classical composite mechanical model. The highest elastic modulus and highest permittivity were obtained for the untreated MFC and A‐MFC composites with 5 and 1 wt%.

2021

Cloth catalysts in water denitrification. II. Removal of nitrates using Pd-Cu supported on glass fibers

Lioubov Kiwi, Albert Renken

The use of glass fibers in the form of woven cloth (GFC), as a new type of catalytic support, was studied for the reduction of aqueous nitrate solutions using a Pd/Cu–GFC catalyst. The activity (per gram Pd) and selectivity to nitrogen were found to be comparable with those found for Pd–Cu catalysts supported on the other carriers. The maximal initial removal activity was found for a catalyst with a Pd/(Pd+Cu) ratio of 0.81. The corresponding activity was 0.7 mmol min-1 (gPd)-1, and the selectivity was 97 mol% at 25°C and pH 6.5 for initial nitrate concentration of 100 mg l-1. The selectivity to nitrogen declined at high conversions of nitrate and high pH.

2001

Novel Analytical Methods for Allergy-Related Studies

Mikaël Frossard

EPFL2020