Tailoring 3-component photoinitiating systems for use as efficient photopolymerizable holographic material

8 pagesInternational audienceTo enhance the efficiency of photopolymerizable systems as holographic recording materials, the use of 3-component photoinitiating systems was explored. In order to get more insight into the hologram formation, gratings' recording curves were compared to those of monomer conversion obtained by RTFTIR spectroscopy. This work outlines the differences between the photoinitiating systems. A holographic 3-component recording material giving rise to thick phase holograms with both high diffraction yield and high rate of formation is highlighted

Short-term Organic Carbon Release and Chlorine Disinfectant Decay for Cross-linked Polyethylene (PEX) Plumbing Pipes

The use of cross-linked polyethylene (PEX) plumbing pipes has grown in popularity for residential applications. However, PEX pipes can leach organic materials into water that can enable biofilm growth, cause off-tastes and -odors, and may react with disinfectants to form disinfection by-products (DBP). Varied manufacturing processes that are applied to create PEX pipes add to the complexity of understanding organic materials released. In this study, organic carbon release from three PEX pipe brands was monitored for up to five days using a series of stagnation periods. Seven stagnation periods of 1, 2, 4, 8, 24, 72, and 120 hours were conducted at 50 degrees Celsius with varying initial chlorine concentrations for a type A (PEX-a), type B (PEX-b), and type C (PEX-c) brand. Pipes were exposed to chlorinated tap water synthesized in the lab. Water exposed to these pipes was analyzed to determine total organic carbon (TOC), assimilable organic carbon (AOC), total chlorine, and free chlorine concentrations. Results show that all pipe brands had different chlorine decay rates and TOC concentrations. Chlorine residual decayed the slowest and fastest for PEX-A pipes and PEX-C pipes, respectively. Chlorine completely decayed in most pipes by 24 hours when the initial chlorine concentration was 2.0 mg/L. PEX-B leached the most amount of contaminants, with a TOC concentration that far exceeded 2.0 mg/L within 24 hours. AOC concentrations tended to increase over time for all pipes. Future work should include additional brands, aged PEX pipes, different flow conditions, temperatures, and longer stagnation periods

Photocyclic initiating system for free radical photopolymerization studied through holographic recording

International audienceThis paper discusses the efficiency of photocyclic initiating system (PCIS) based on a pyrromethene dye (EMP), an amine as electron donor (NPG) and an iodonium salt as electron acceptor (I250) under homogenous irradiation and holographic recording. It is shown that the PCIS is more efficient than the corresponding two component systems. This high efficiency is due to a photocyclic reaction that takes places during the irradiation, inducing the recovery of the dye in the ground state and the formation of two initiating radicals. The beneficial effect on the rate of grating formation and on the diffraction efficiency is clearly noticed. At high irradiation time, the fast polymerization observed with EMP-NPG-I250 even induces the polymerization in the dark fringes leading to a decrease of the holographic diffraction efficiency. This confirms the high performance of the photoinitiating system which can be used in holographic recording provided that the irradiation dose could be controlled

Influence of ionic additives on triclinic calcium pyrophosphate dihydrate precipitation

Triclinic calcium pyrophosphate dihydrate (t- CPPD) crystals are one of the two polymorphs of microcrystals that have been found in the joints of patients suffering from pseudogout. However, there is currently no treatment for inhibiting the formation of these crystals, which present a high inflammatory potential. In this context we studied in vitro the precipitation of t-CPPD in a stirred reactor under pH- and temperature-controlled conditions and determined the effect of selected biologically relevant ionic additives (Mg2+, Cu2+, Fe3+, Zn2+, S2O3 2−) on its formation. The results showed that 1 mM Fe3+, Zn2+, or Cu2+ induced the most significant changes by partly inhibiting the crystallization of t-CPPD and favoring the formation of an amorphous-CPP phase (98 wt %) in the presence of Fe3+ or a monoclinic-CPPD phase (78 or 71 wt %, respectively) in the presence of Zn2+ or Cu2+. Correlations between 31P solid-state NMR, XRD, and elemental analyses showed that the additive cations are inserted into the monoclinic-CPPD and/or amorphous-CPP phases. This study, which combines structural, morphological, and elemental analyses, paves the way toward a deeper comprehension of the role of ionic additives in preventing the formation of CPPD crystalline phases, and is a key step in long-term development of an effective therapeutic treatmen

Photopolymérisation et modulation d'indice de réfraction en holographie

5 pagesNational audienceLes systèmes ici mis en œuvre en tant que support d'enregistrement holographique reposent sur la mise en commun des compétences, d'une part, du LPIM dans le domaine des photoamorceurs et des supports d'enregistrement holographique, et celles, d'autre part, du laboratoire Foton. Les systèmes photoamorceurs considérés sont composés de trois éléments : un colorant et deux co-amorceurs (un donneur d'électron et un accepteur d'électron). Le système SFH+-NPG-ClHABI est, après optimisation des formulations, celui qui conduit aux meilleures performances holographiques, tant du point de vue rendement final de diffraction que de la vitesse de formation du réseau, tout en se stabilisant rapidement à son maximum

Optimisation de nouveaux systèmes photoamorceurs de polymérisation pour le stockage d'informations par holographie

2 pagesNational audienceDifférents systèmes photoamorceurs mettant en jeu trois composants et destinés à la polymérisation d'un mélange d'acrylates sont ici optimisés en tant que support pour le stockage d'informations par holographie. Ces matériaux donnent naissance à des réseaux de phase épais, fonctionnant en transmission. L'étude basée sur l'enregistrement de réseaux sinusoïdaux sous forme d'une modulation d'indice de réfraction a permis de comparer les systèmes 3-composants aux 2-composants correspondants, les premiers étant plus performants d'un point de vue photochimique (vitesse et taux de polymérisation élevés). L'optimisation des matériaux a conduit à des rendements de diffraction corrigés dans l'ordre 1 supérieurs à 90%

Optimization of a photopolymerizable material based on a photocyclic initiating system using holographic recording

9 pagesInternational audienceA set of photoinitiating systems (PIS) for free radical photopolymerization was studied using time-resolved spectroscopic experiments, real-time FTIR and holographic recording. It is shown that the efficiency of the photoinitiating system can be drastically increased when a redox additive is added to the conventional dye/coinitiator system by virtue of photocyclic behaviour. The homogeneous photopolymerization process was found to reach a fast vitrification, limiting the conversion at about 55%. By contrast, holographic recording underlines the differences in photoinitiating system reactivity, allowing diffraction efficiencies close to unity for the most reactive PIS

Oxidative photopolymerization of thiol-terminated polysulfide resins. Application in antibacterial coatings

A UV photoinduced cross-linking of non-modified commercial poly(disulfide) resins (Thioplast) is reported via the air oxidative photocoupling of terminal thiol functions. Catalyzed by a photogenerated guanidine base (TBD), this step-growth photopolymerization is useful to maximize disulfide functions content. The mechanism proceeds through thiol deprotonation into thiolate anions, further oxidized into thiyl radicals, eventually dimerizing into disulfide cross-links. Starting with a detailed structural characterization of the thiol-terminated resin, photooxidative kinetics are studied under exposure to a polychromatic medium-pressure Hg arc using Raman and infrared spectroscopy. The effects of irradiance, film thickness, photobase concentration, resin molar mass, and content of an additional polythiol monomer (reactive diluent) have been investigated. In an effort of upscaling, irradiation under a 365 nm LED panel has enabled the fast preparation of 1.5 μm thick cross-linked poly(disulfide) coatings in a matter of minutes. Capitalizing on the ability of residual thiol groups to react with silver cations, a post-functionalization has been successfully performed, leading to films exhibiting at their surface stable thiolate-silver bonds as proved by X-ray photoelectron spectroscopy. Despite the well-established biocide action of silver ions, no antibacterial action has been evidenced by confocal fluorescence microscopy because of insufficient release

Entwicklung IT-basierter interorganisationaler Krisenmanagement-Infrastrukturen für Stromausfälle

Große Stromausfälle, wie beispielsweise der Ausfall der Stromversorgung im Nordosten der USA (2003) oder der Ausfall in weiten Teilen von West-Europa (2005), machen die fundamentale Bedeutung von Strom in unserem täglichen Leben deutlich. Sie zeigen auch, welche wichtige Rolle die Kooperation und Zusammenarbeit zwischen allen Beteiligten der Bewältigungs- und Wiederherstellungsarbeit spielt. Die Erfahrungen aus diesen Ausfällen legen nahe, dass Stromnetzbetreiber, Feuerwehr, Polizei, Behörden und Bürger einer Vielzahl von unterschiedlichen Herausforderungen in der interorganisationalen Kommunikation und innerhalb von Informations- und Koordinierungsprozessen gegenüberstehen. Ziel des Forschungsprojekts "InfoStrom", welches vom Bundesministerium für Bildung und Forschung seit 2010 und bis Ende 2013 gefördert wird, ist die Entwicklung von Konzepten, um diese Zusammenarbeit zu unterstützten und letztlich zu verbessern. In diesem Beitrag werden potentielle Fragen und zukünftige Themen und erzielte Ergebnisse dargestellt, die sich auf die benutzerzentrierte Technologieentwicklung im Krisenmanagement und auf domain-spezifische Probleme, wie die Verbesserung der Integration von Bürgern in das Krisenmanagement, den Umgang mit Informationsunsicherheiten oder die Unterstützung des interorganisationalen Lernens, beziehen

The TAM-TB Assay—A Promising TB Immune-Diagnostic Test With a Potential for Treatment Monitoring

Tuberculosis (TB) epidemiology is changing in Western and Central Europe due to the rise in immigration and refugees fleeing high-TB-burden areas of war and devastation. The change in local demography and the lack of sensitive and specific TB diagnostic and monitoring tools, especially for cases of childhood TB, leads to either missed cases or over-treatment of this group. Here we present a promising new diagnostic approach, the T cell activation marker (TAM)-TB assay, and its performance in a case of extra-pulmonary TB occurring in a 16 year old refugee from Afghanistan. This assay is based on the characterization of 3 activation markers (CD38, HLA-DR, and Ki67) and one maturation marker (CD27) on M. tuberculosis-specific CD4 T cells. It was performed at time-points TO (10 days), T1 (1 month), T2 (6 months), and T3 (12 months) post-treatment initiation. All markers were able to detect active tuberculosis (aTB) within this patient at T0 and reverted to a healthy/LTBI phenotype at the end of treatment. Tantalizingly, there was a clear trend toward the healthy/LTBI phenotype for the markers at T1 and T2, indicating a potential role in monitoring anti-TB treatment in the future. This assay may therefore contribute to improved TB diagnostic algorithms and TB treatment monitoring, potentially allowing for individualization of TB treatment duration in the future