Scope and limitation of the copper free thermal Huisgen cross-linking reaction to stabilize the chromophores orientation in electro-optic polymers

New methacrylate copolymers incorporating two complementary thermally cross-linkable groups (azide or ethynyl) for implementation in electro-optic devices were synthesized and their nonlinear optical properties were investigated. These copolymers were prepared from a monomer containing Disperse Red 1 (DR1) as active NLO chromophore which is end substituted either by an azide or ethynyl group connected via a rigid (phenyl) or flexible spacer (alkyl chain). The second monomer is either a trimethylsilyl-propargyl methacrylate, or an azidopropyl methacrylate or a trimethylsilyl-phenyl methacrylate. The determination of the reactivity ratios showed that the monomer containing the DR1 chromophore is more reactive than trimethylsilyl-propargyl methacrylate. The cross-linking temperatures of these polymers range from 150 °C to 187 °C depending on the rigidity of the spacers connecting the cross-linkable units. These polymers displayed relatively high macroscopic electro-optic stability, enhanced upon cross-linking by more than 40 °C relative to non-cross-linked polymers. The results underscore the importance of the flexibility of the spacers to achieve the stable bulk electro-optic response. While rigidity is favorable to maintain the orientation of the chromophores, the optimal polymer is the one containing a flexible and a rigid spacer, since the mobility of the reactive groups is a key parameter which guarantees a high cross-linking conversion within the polymer. This study demonstrates the versatility of this new cross-linking process because we showed that the reactive groups (azide or trimethylsilylacetylated groups) can be interconverted (on the chromophore or as polymer side chain) with no change on the overall electro-optic activity and its thermal stability. Furthermore, preliminary kinetic study indicates that the Huisgen reaction rate can be controlled by the substituent on the ethynyl group opening the possibility to tune the cross-linking temperature by the careful choice of this substituent

OPTIMIZING AND PROMOTING MECHANICAL WEED CONTROL IN ARABLE CROPS

Within an overall strategy of weed flora management, mechanical weed control practices are complementary solutions to agronomic levers (crop rotation, tillage...) in weed control. Acquiring knowledge and communicating on the effectiveness of mechanical practices and tools appear essential. The "Mechanical Weed Control" project in France conducted between 2009 and 2012 made progress in this regard. The project shows that research activities are to be continued (experimentation, analysis of practices) and should be complemented by promotion that focuses on participatory approaches where farmers are involved in the implementation of these new practices

Portrait d’initiatives québécoises de recherche ayant utilisé une méthode dite d’enquête citoyenne

Ce rapport de recherche présente, dans un premier temps, un cadre de réflexion propice à la réalisation d’activités de recherche qui reposent sur une mobilisation de connaissances détenues par la population d’un territoire local. Dans un deuxième temps, cinq expériences de collecte de données impliquant une participation citoyenne sont présentées. Deux de ces expériences illustrent des démarches ayant pour objectif de mobiliser des citoyennes. Les trois autres sont des exemples où la collecte d’informations détenues par la population locale est vue comme un plus pour définir des projets qui soient mieux ancrés dans leur communauté

Electrical conductivity of plasmas of DB white dwarf atmospheres

The static electrical conductivity of non-ideal, dense, partially ionized helium plasma was calculated over a wide range of plasma parameters: temperatures $1\cdot 10^{4}\textrm{K} \lesssim T \lesssim 1\cdot 10^{5}\textrm{K}$ and mass density $1 \times 10^{-6} \textrm{g}/\textrm{cm}^{3} \lesssim \rho \lesssim 2 \textrm{g}/\textrm{cm}^{3}$. Calculations of electrical conductivity of plasma for the considered range of plasma parameters are of interest for DB white dwarf atmospheres with effective temperatures $1\cdot 10^{4}\textrm{K} \lesssim T_{eff} \lesssim 3\cdot 10^{4}\textrm{K}$. Electrical conductivity of plasma was calculated by using the modified random phase approximation and semiclassical method, adapted for the case of dense, partially ionized plasma. The results were compared with the unique existing experimental data, including the results related to the region of dense plasmas. In spite of low accuracy of the experimental data, the existing agreement with them indicates that results obtained in this paper are correct

Herpes simplex virus ICP27 protein directly interacts with the nuclear pore complex through NUP62, inhibiting host nucleocytoplasmic transport pathways

The herpes simplex virus ICP27 protein is important for the expression and nuclear export of viral mRNAs. Although several binding sites have been mapped along the ICP27 sequence for various RNA and protein partners including the transport receptor TAP of the host cell nuclear transport machinery, several aspects of ICP27 trafficking through the nuclear pore complex remain unclear. We investigated if ICP27 could interact directly with the nuclear pore complex itself, finding that ICP27 directly binds the core nucleoporin Nup62. This is confirmed through co-immunoprecipitation and in vitro binding assays with purified components. Mapping with ICP27 deletion and point mutants further shows that the interaction requires sequences in both the N and C-termini of ICP27. Expression of wildtype ICP27 protein inhibited both classical, importin α/β-dependent and transportin dependent nuclear import. In contrast, an ICP27 point mutant that does not interact with Nup62 had no such inhibitory effect. We suggest that ICP27 association with Nup62 provides additional binding sites at the nuclear pore for ICP27 shuttling thus supporting ICP27-mediated transport. We propose that ICP27 competes with some host cell transport receptors for binding, resulting in inhibition of those host transport pathways

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Combined search for the quarks of a sequential fourth generation

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

The cell biology of the Trichosporon-Host interaction

Fungi of the genus Trichosporon are increasingly recognized as causative agents of superficial and invasive fungal disease in humans. Although most species are considered commensals of the human skin and gastrointestinal tract, these basidiomycetes are an increasing cause of fungal disease among immunocompromised hosts, such as hematological patients and solid organ transplant recipients. The initiation of commensal or pathogenic programs by Trichosporon spp. involves the adaptation to the host microenvironment and its immune system. However, the exact virulence factors activated upon the transition to a pathogenic lifestyle, including the intricate biology of the cell wall, and how these interact with and subvert the host immune responses remain largely unknown. Here, we revisit our current understanding of the virulence attributes of Trichosporon spp., particularly T. asahii, and their interaction with the host immune system, and accommodate this knowledge within novel perspectives on fungal diagnostics and therapeutics.This work was supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER) (NORTE-01-0145-FEDER000013), and by Fundação para a Ciência e Tecnologia (FCT) (IF/00735/2014 to AC, and SFRH/BPD/96176/2013 to CC).info:eu-repo/semantics/publishedVersio