Laser-Driven Precipitation and Modification of Silver Nanoparticles in Soda Lime Glass Matrix Monitored by On-line Extinction Measurements

In this work, we investigated the effect of nanosecond laser irradiation at 532?nm on precipitation of Ag nanoparticles (NPs) in soda lime glasses doped with silver in the Ag^?+??CNa^?+? ion-exchange process. Formation and subsequent modification of Ag NPs during laser irradiation were studied by on-line extinction measurements making use of the localized surface plasmon resonance (LSPR). These investigations were further completed using scanning and transmission electron microscopies to examine the average size and distribution of nanoparticles within the sample. It has been shown that formation of NPs, its kinetics and the particle size strongly depend on the fluence and the total number of deposited laser pulses. It has been found that Ag NPs form after some specific number of pulses and they rapidly grow in size and number until some maximal value of extinction has been reached. Further irradiation of such samples only results in destruction of precipitated NPs due to photo-breakup, laser ablation confirmed by strong plasma emission observation. Moreover, due to strong irradiation, the host matrix can also be affected by changing its refractive index which manifests as the blue shift of the LSPR.     

A robust platform for chemical genomics in bacterial systems

While genetic perturbation has been the conventional route to probing bacterial systems, small molecules are showing great promise as probes for cellular complexity. Indeed, systematic investigations of chemical-genetic interactions can provide new insights into cell networks and are often starting points for understanding the mechanism of action of novel chemical probes. We have developed a robust and sensitive platform for chemical-genomic investigations in bacteria. The approach monitors colony volume kinetically using transmissive scanning measurements, enabling acquisition of growth rates and conventional endpoint measurements. We found that chemical-genomic profiles were highly sensitive to concentration, necessitating careful selection of compound concentrations. Roughly 20,000,000 data points were collected for 15 different antibiotics. While 1052 chemical-genetic interactions were identified using the conventional endpoint biomass approach, adding interactions in growth rate resulted in 1564 interactions, a 50–200% increase depending on the drug, with many genes uncharacterized or poorly annotated. The chemical-genetic interaction maps generated from these data reveal common genes likely involved in multidrug resistance. Additionally, the maps identified deletion backgrounds exhibiting class-specific potentiation, revealing conceivable targets for combination approaches to drug discovery. This open platform is highly amenable to kinetic screening of any arrayable strain collection, be it prokaryotic or eukaryotic.     

Molecular Mechanics: The Conjugate Nitro Group Parameters in the MM2 Force Field

The conjugated nitro group has been included in the π system calculation within the MM2 force field. New parameters have been estimated by a statistical process from X-ray molecular structures recorded in the C.S.D.S. Comparison of the corresponding results with those given by the MM2(91) force field parameters show a clear improvement for dihedral and bond angles. For N-O and C-N bond lengths a slight global improvement is also observed. A closer examination of the results for the latter bond shows that sometimes MM2(91) gives better results for six membered ring nitro compounds. By contrast the parameters proposed here are more adapted to five membered ring derivatives. The derived linear relations permit the study of molecules over a wider range of π indices. The introduction of a correction factor to the calculated molecular π dipole moment in conjunction with a necessary reestimation of some σ-bond dipole moments also leads to improved total molecular dipole moments.     

Fruit damages caused by the broad-winged bush katydid,Scudderia pistillata (Orthoptera: Tettigoniidae) in commercial cranberry bog

In August 2018, unidentified damages were reported on cranberries in a conventional bog located in Quebec (Eastern Canada). Following a field inspection, high percentage of nibbled fruits as well as katydids (Orthoptera: Tettigoniidae) were observed. Several individuals (nymphs and adults) were seen feeding directly on the fruits. Specimens were captured and sent to the “Laboratoire d'expertise et de diagnostic en phytoprotection” of the “Quebec Ministry of Agriculture, Fisheries and Food" (LEDP-MAPAQ). They were identified as Scudderia pistillata Brunner von Wattenwyl (Orthoptera: Tettigoniidae). Subsequently, a systematic fruit sampling was realized into the beds where damages were observed to assess spatial patterns of infestation. To our knowledge, it constitutes the first mention of significant damages associated to this species in cranberry bogs and, in some cases, up to 5% damages to the fruits were observed. This observation suggests that S. pistillata represents a potential pest for this crop. Additionally, a decrease of damage rates was observed when distancing from the north-eastern corner of the bog. Hypothesis in regards of damages' spatial pattern is discussed.     

Ebolavirus VP35 Coats the Backbone of Double-Stranded RNA for Interferon Antagonism

Recognition of viral double-stranded RNA (dsRNA) activates interferon production and immune signaling in host cells. Crystal structures of ebolavirus VP35 show that it caps dsRNA ends to prevent sensing by pattern recognition receptors such as RIG-I. In contrast, structures of marburgvirus VP35 show that it primarily coats the dsRNA backbone. Here, we demonstrate that ebolavirus VP35 also coats the dsRNA backbone in solution, although binding to the dsRNA ends probably constitutes the initial binding event.     

Advanced magnetic resonance imaging techniques to better understand multiple sclerosis

Magnetic resonance imaging (MRI) has considerably improved the diagnosis and monitoring of multiple sclerosis (MS). Conventional MRI such as T₂-weighted and gadolinium-enhanced T₁-weighted sequences detect focal lesions of the white matter, damage of the blood–brain barrier, and tissue loss and inflammatory activity within lesions. However, these conventional MRI metrics lack the specificity required for characterizing the underlying pathophysiology, especially diffuse damage occurring throughout the whole central nervous system. To overcome these limitations, advanced MRI techniques have been developed to get more sensitive and specific parameters of focal and diffuse brain damage. Among these techniques, magnetization transfer imaging, diffusion MRI, functional MRI, and magnetic resonance spectroscopy are the most significant. In this article, we provide an overview of these advanced MRI techniques and their contribution to the better characterization and understanding of MS.     

First Jurassic occurence of Enoploclytia M’Coy, 1849 (Crustacea: Decapoda: Erymidae)

Among the Erymidae Van Straelen, 1925, known as early as the Late Permian (Changhsingian) and widespread in the Jurassic, the genus Enoploclytia M’Coy, 1849 seems to have a late appearance because of its lack before the Cretaceous. Until now, the oldest representative was E. augustobonae Devillez, Charbonnier, Hy?ný and Leroy, 2016 from the Early Cretaceous (Barremian) of the eastern Paris basin (France). However, a new fossil collected in Normandy (France), showing the typical carapace groove pattern of Enoploclytia, attests the presence of the genus in the Late Jurassic (Oxfordian).     

Étude techno-économique du Moustérien de Pradayrol (Caniac-du-Causse,Lot) : entre mobilité des ressources lithiques et adaptation aux matériaux locaux,un exemple de gestion complémentaire des quartz et silex au Paléolithique moyen récent en Quercy

The Mousterian locus at Pradayrol (Caniac-du-Causse, Lot, France) produced an important lithic assemblage, composed primarily of quartz, alongside a varied flint component. Our technological analysis reveals the presence of several chaînes opératoires adapted to the morphology and mechanical properties of different raw materials. This is especially evident in the use of the bipolar on-anvil technique on quartz cobbles and discoidal flaking methods on both quartz and relatively local flints. Flint from the Périgord region provides evidence for a fragmented and ramified Levallois chaîne opératoire, different from that observed with local raw materials. These techno-economic features are similar to those documented for many late Middle Palaeolithic assemblages in the Quercy. The Neanderthal occupation of Pradayrol seems to reflect a balance between technical know-how and adaptations to the raw material constraints.