Small angle neutron scattering from 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids ([C(n)mim][PF6], n=4, 6, and 8)

The presence of local anisotropy in the bulk, isotropic, and ionic liquid phases-leading to local mesoscopic inhomogeneity-with nanoscale segregation and expanding nonpolar domains on increasing the length of the cation alkyl-substituents has been proposed on the basis of molecular dynamics (MD) simulations. However, there has been little conclusive experimental evidence for the existence of intermediate mesoscopic structure between the first/second shell correlations shown by neutron scattering on short chain length based materials and the mesophase structure of the long chain length ionic liquid crystals. Herein, small angle neutron scattering measurements have been performed on selectively H/D-isotopically substituted 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids with butyl, hexyl, and octyl substituents. The data show the unambiguous existence of a diffraction peak in the low-Q region for all three liquids which moves to longer distances (lower Q), sharpens, and increases in intensity with increasing length of the alkyl substituent. It is notable, however, that this peak occurs at lower values of Q (longer length scale) than predicted in any of the previously published MD simulations of ionic liquids, and that the magnitude of the scattering from this peak is comparable with that from the remainder of the amorphous ionic liquid. This strongly suggests that the peak arises from the second coordination shells of the ions along the vector of alkyl-chain substituents as a consequence of increasing the anisotropy of the cation, and that there is little or no long-range correlated nanostructure in these ionic liquids.

Direct Quantification of Inorganic Polyphosphate in Microbial Cells Using 4 '-6-Diamidino-2-Phenylindole (DAPI)

Inorganic polyphosphate (polyP) is increasingly being recognized as an important phosphorus sink within the environment, playing a central role in phosphorus exchange and phosphogenesis. Yet despite the significant advances made in polyP research there is a lack of rapid and efficient analytical approaches for the quantification of polyP accumulation in microbial cultures and environmental samples. A major drawback is the need to extract polyP from cells prior to analysis. Due to extraction inefficiencies this can lead to an underestimation of both intracellular polyP levels and its environmental pool size: we observed 23-58% loss of polyP using standard solutions and current protocols. Here we report a direct fluorescence based DAPI assay system which removes the requirement for prior polyP extraction before quantification. This increased the efficiency of polyP detection by 28-55% in microbial cultures suggesting quantitative measurement of the intracellular polyP pool. It provides a direct polyP assay which combines quantification capability with technical simplicity. This is an important step forward in our ability to explore the role of polyP in cellular biology and biogeochemical nutrient cycling.

Biotransformation of 2,4,6-trinitrotoluene (TNT) by ectomycorrhizal basidiomycetes

The ability of four ectomycorrhizal basidiomycetes to biotransform 2,4,6-trinitrotoluene (TNT) in axenic culture was tested. All species were capable of TNT biotransformation to a greater or lesser extent. When biotransformation was expressed on a biomass basis 4 out of the 5 isolates tested were equally efficient at transforming TNT. The factors regulating TNT biotransformation were investigated in detail for one fungus, Suillus variegatus. When the fungus was grown under nitrogen limiting conditions the rate of biotransformation decreased relative to nitrogen sufficient conditions, but no decrease was observed under short term carbon starvation. Extracellular enzymes of S. variegatus could transform TNT, but transformation was greater in intact cells. The mycelial cell wall fraction did not degrade TNT. The TNT concentration that caused 50% reduction in biomass (EC₅₀) for S. variegatus was within the range observed for other basidiomycete fungi being between 2-10 μg mL^-1. The potential use of ectomycorrhizal basidiomycetes as in-situ bioremediation agents for TNT contaminated soils is discussed.

4-6-20, signature de la Paix avec la Hongrie, la salle du Grand Trianon après la signature : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59532

4-6-20, signature de la Paix avec la Hongrie, départ des délégués hongrois [sur les marches du perron] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59533

4-6-20, Versailles, roi de Grèce [signature de la Paix avec la Hongrie, descente des marches du perron des plénipotenciaires] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59535

4-6-20, Versailles, signature de la Paix avec la Hongrie, M. Millerand [passant devant un piquet d'honneur] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59534

4-6-20, signature de la Paix avec la Hongrie, en tête M. Benart [i.e. Beynar] hongrois [passant devant un piquet d'honneur à Versailles] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59536

4-6-20, signature de la Paix avec la Hongrie, M. Wallace ambassadeur des États-Unis [montant les marches du perron] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59538

4-6-20, signature de la Paix avec la Hongrie, le roi de Grèce [montant les marches du perron du Grand Trianon] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 59539