Search results for "Wave"
showing 10 items of 6009 documents
MICROWAVE-ASSISTED FUNCTIONALIZATION OF HALLOYSITE NANOTUBE SURFACE
2014
Halloysite, Al2Si2O5·2H2O, is a naturally occurring two-layered alluminosilicate, chemically similar to kaolin, which has a predominantly high-aspect-ratio hollow tubular structure in the submicrometer range and an internal diameter in the nanometer range. The size of halloysite nanotubes (HNTs), generally varies from 50 to 70 nm in external diameter, ca. 15 nm diameter lumen, and 0.5 to 1 μm in length. Halloysite tubes have aluminol (Al-OH) groups on the internal surface and siloxan groups (Si-O-Si) on the external surface. The very large diameter of the halloysite lumen makes it potentially suitable for the accommodation of a range of guests. In recent reports, for example, the mesoporous…
GREEN CONDITIONS FOR THE SUZUKI REACTIONS BY USING MICROWAVE IRRADIATION AND MODIFIED HALLOYSITE/Pd CATALYST
2014
Halloysite nanotube (HNT) is an emerging biocompatible material with appealing perspective for technological applications, such as in catalysis1 and in pharmaceutical research.2 Halloysite is a double-layered aluminosilicate mineral that has a predominantly hollow tubular structure. The functionalization of HNTs is a good strategy to introduce an organic moiety onto the external surface and, therefore, to obtain innovative catalyst supports.3 We have modified the external surface of halloysite nanotube with octylimidazolium moieties (HNT-IL) by microwave irradiation in solvent-free conditions and we have have employed this material as support catalyst of Pd nanoparticles. The new HNT/Pd cat…
Heat wave occurrences over Senegal during spring: regionalization and synoptic patterns.
2020
18 pages; International audience; Based on 12 Senegalese stations of the Global Summary of the Day (GSOD) database (1979–2014), heat waves (HW) are defined for each station in spring (March–April–May, the hottest season in Senegal) as the daily maximum temperature (Tx), minimum temperature (Tn), or average apparent temperature of the day (AT), exceeding the corresponding 95% mobile percentile for at least three consecutive days. A hierarchical cluster analysis used to regionalize HW in these 12 stations is applied to simultaneous occurrences of daily temperature peaks over their 95% mobile percentiles. Three homogeneous zones of four stations each are identified (Zone 1, Zone 2 and Zone 3),…
Infection success of Echinoparyphium aconiatum (Trematoda) in its snail host under high temperature: role of host resistance
2014
Background Extreme weather events such as summer heat waves become more frequent owing to global climate change and are predicted to alter disease dynamics. This is because high temperatures can reduce host immune function. Predicting the impact of climate change on host-parasite interactions is, however, difficult as temperature may also affect parasite infective stages and other host characteristics determining the outcome of interaction. Methods Two experiments were conducted to investigate these phenomena in a Lymnaea stagnalis–Echinoparyphium aconiatum (Trematoda) interaction. In the first experiment, the effects of exposure of snails to experimental heat waves [maintenance at 25°C vs.…
Urban Heat Island (UHI) and heat waves: what relations?
2018
With four years of measurements and alarge sample of stations, the MUSTARDijon network allows for a detailed characterization of the Urban HeatIsland (UHI), a warm season phenomenon. But UHI and maximum temperature values are out of phase at twodistinct time-scales. Seasonally, the maxima of UHI occur from May to July, i.e. before the annual peak oftemperature (July to August). At a daily time-scale, analysis of the two heat waves of July 2015 shows a lag of afew days between the peak of UHI and the heat wave. Two hypotheses are suggested to explain these lags:changes in radiative conditions and/or energy fluxes between the ground surface and the atmosphere.
Les vagues de chaleur au Sahel : caractérisation, mécanismes, prévisibilité.
2016
The mechanisms controlling Sahelian heat wave (HW) variability are examined on the period 1979-2014 using the GSOD observational database and ERA-Interim reanalyses. HW events are analyzed through all terms of the atmospheric energy balance, showing a predominant role of incoming shortwave radiation on daily maximum temperature (Tx) and atmospheric water vapor on minimum temperature (Tn). The low-frequency warming trend, not explained by the previous terms, is thought to relate to the increase of greenhouse gases concentrations, due to anthropogenic emissions. The predictability of Sahelian HW events is assessed for lead times reaching up to 15 days. The model's skill, biases and uncertaint…
Les Local Climate Zones face à la canicule de 2018 à Dijon.
2019
Air temperatures measured by the MUSTARDijon network are analyzed during the summer 2018 (July 24 - August 8) heat wave. The WUDAPT method is applied to Dijon to identify Local Climate Zones (LCZs). Diurnal rhythms and nighttime mean temperatures are analyzed according to LCZs as well as to altitude and distance to the city center. During warm nights, altitude plays a negligible role. The temperatures depend to the distance of the city center. They are also associated to the anthropization summarized by the LCZs. Form of the building and vegetation are the two keys to understand and modulate the night temperatures which have the greatest impact on human health during heat waves.
Simple two-step synthesis of 2,4-disubstituted pyrroles and 3,5-disubstituted pyrrole-2-carbonitriles from enones
2014
The cyclocondensation of enones with aminoacetonitrile furnishes 3,4-dihydro-2H-pyrrole-2-carbonitriles which can be readily converted to 2,4-disubstituted pyrroles by microwave-induced dehydrocyanation. Alternatively, oxidation of the intermediates produces 3,5-disubstituted pyrrole-2-carbonitriles.
Review of Particle Physics
2020
The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143 new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, …
Closed-Loop Acoustic Stimulation During Sleep in Children With Epilepsy: A Hypothesis-Driven Novel Approach to Interact With Spike-Wave Activity and …
2019
Slow waves, the electroencephalographic (EEG) hallmark of deep sleep, can be systematically manipulated by acoustic stimulation: stimulation time-locked to the down phase of slow waves reduces, whereas stimulation time-locked to the up phase increases slow waves. Spike-waves during sleep seem to be related to slow waves, raising the question of whether spike-waves can be systematically influenced by such acoustic stimulation. In five pediatric patients, all-night EEG was recorded, combined with real-time slow wave detection. Throughout the night, acoustic stimulation was performed in a 3 × 5-min-block design (no stimulation—stimulation—no stimulation). Tones were applied time-locked either …