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51.
52.
Romain Gautier Florian Massuyeau Gabin Galnon Michael Paris 《Advanced materials (Deerfield Beach, Fla.)》2019,31(14)
Hybrid metal halides containing perovskite layers have recently shown great potential for applications in solar cells and light‐emitting diodes. Such compounds exhibit quantum confinement effects leading to tunable optical and electronic properties. Thus, broadband white‐light emission has been observed from diverse metal halides and, owing to high color rendering index, high thermal stability, and low‐temperature solution processability, these materials have attracted interest for application in solid‐state lighting. However, the reported quantum yields for white photoluminescence (PLQY) remain low (i.e., in the range 0.5–9%) and no approach has shown to successfully increase the intensity of this emission. Here, it is demonstrated that the quantum efficiencies of hybrid metal halides can be greatly enhanced if they contain a polymorph of the [PbX4]2? perovskite‐type layers: the [PbX4]2? post‐perovskite‐type chains showing a PLQY of 45%. Different piperazines lead to a hybrid lead halide with either perovskite layers or post‐perovskite chains influencing strongly the presence of self‐trapped states for excitons. It is anticipated that this family of hybrid lead halide materials could enhance all the properties requiring the stabilization of trapped excitons. 相似文献
53.
[4]Helicene–Squalene Fluorescent Nanoassemblies for Specific Targeting of Mitochondria in Live‐Cell Imaging 下载免费PDF全文
Andrej Babič Simon Pascal Romain Duwald Dimitri Moreau Jérôme Lacour Eric Allémann 《Advanced functional materials》2017,27(33)
Ester, amide, and directly linked composites of squalene and cationic diaza [4]helicenes 1 are readily prepared. These lipid‐dye constructs 2 , 3 , and 4 give in aqueous media monodispersed spherical nanoassemblies around 100–130 nm in diameter with excellent stability for several months. Racemic and enantiopure nanoassemblies of compound 2 are fully characterized, including by transmission electron microscope and cryogenic transmission electron microscope imaging that did not reveal higher order supramolecular structures. Investigations of their (chir)optical properties show red absorption maxima ≈600 nm and red fluorescence spanning up to the near‐infrared region, with average Stokes shifts of 1350–1550 cm?1. Live‐cell imaging by confocal microscopy reveals rapid internalization on the minute time scale and organelle‐specific accumulation. Colocalization with MitoTracker in several cancer cell lines demonstrates a specific staining of mitochondria by the [4]helicene–squalene nanoassemblies. To our knowledge, it is the first report of a subcellular targeting by squalene‐based nanoassemblies. 相似文献
54.
Gerald Juma Gilles Clément Peter Ahuya Ahmed Hassanali Sylvie Derridj Cyrile Gaertner Romain Linard Bruno Le Ru Brigitte Frérot Paul-André Calatayud 《Journal of chemical ecology》2016,42(5):394-403
The chemical composition of plant surfaces plays a role in selection of host plants by herbivorous insects. Once the insect reaches the plant, these cues determine host acceptance. Laboratory studies have shown that the stem borer Busseola fusca (Lepidoptera: Noctuidae), an important pest of sorghum and maize in sub-Saharan Africa, is able to differentiate between host and non-host plant species. However, no information is available on the cues used by this insect to seek and accept the host plant. Thus, the role of surface phytochemical stimuli on host selection and oviposition by B. fusca was studied in the laboratory using two host plants, sorghum, Sorghum bicolor, and maize, Zea mays, and one non-host plant, Napier grass, Pennisetum purpureum. The numbers of eggs and egg masses deposited on the three plant species were compared first under no-choice and choice conditions. In both cases, more eggs and egg masses were laid on maize and sorghum than on the non-host. Artificial surrogate stems treated with a water or chloroform surface extract of each plant were then compared with surrogate stems treated with, respectively, water or chloroform as controls, under similar conditions. Surrogate stems treated with plant water extracts did not show an increase in oviposition when compared to controls, indicating that the major compounds in these extracts, i.e., simple sugars and free amino acids, are not significantly responsible for the oviposition preference. By contrast, a chloroform extract of sorghum enhanced oviposition on the surrogate stems compared to the control, while those of maize and Napier grass showed no significant effects. Analysis of the chloroform extract of sorghum showed higher amounts of α-amyrin, ß-amyrin, and n-nonacosane compared to those of maize and Napier grass. A blend of the three chemicals significantly increased oviposition compared to the chloroform-treated control, indicating that these compounds are part of the surface chemical signature of the plant responsible for host recognition and oviposition by B. fusca. 相似文献
55.
This paper presents the abstraction of open consensus and argues for its use as an effective component for building reliable agreement protocols in practical asynchronous systems where processes and links can crash and recover. The specification of open consensus has a decoupled, on‐demand and re‐entrant flavour that make its use very efficient, especially in terms of forced logs, which are known to be major sources of overhead in distributed systems. We illustrate the use of open consensus as a basic building block to develop a modular, yet efficient, total‐order broadcast protocol. Finally, we describe our Java implementation of our open‐consensus abstraction and we convey our efficiency claims through some practical performance measures. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
56.
Denis Lapalme Romain Lemaire Patrice Seers 《International Journal of Hydrogen Energy》2017,42(12):8314-8328
This paper investigates the various techniques used in the literature to calculate the effective Lewis number of two-component (H2/CO and H2/CH4) and three-component fuels (H2/CO/CH4 and H2/CO/CO2) over a wide range of equivalence ratios (0.6 ≤ φ ≤ 1.4) under laminar flame conditions. The most appropriate effective Lewis number formulation is identified through comparison with experimentally extracted Lewis numbers (Le). The paper first identifies the proper methodology to extract the experimental Le from the burned Markstein length of an outwardly propagating flame. Second, the different methodologies for the calculation of the effective Le are presented and compared to experimental results for H2/CH4 and H2/CO mixtures. Based on the experimental results, it is shown that the calculation of the effective Le of mixtures can be divided into a three-step procedure depending on the equivalence ratio: (1) calculation of the Le for each fuel and the oxidizer; (2) use of the Le mixing rule; and (3) assessment of the necessity or not of combining the fuel's and oxidizer's Lewis numbers. The paper shows that, in rich mixtures, the oxidizer Le needs to be taken into account. Lastly, the methodology is validated for H2/CO/CH4 and H2/CO/CO2 fuels. 相似文献
57.
Interactions between flavour compounds and polysaccharides have been studied by exclusion size chromatography, the Hummel and Dreyer method. Hydrogen bonding was found between 2-acetyl thia-zole and dextrines of different degrees of polymerisation. The number of binding sites and the affinity constant increase by increasing the degree of polymerisation. Hydrogen bonding was also responsible for the interactions between xanthane and 1-octen-3-ol or 2-acetyl pyra-zine, with 1 mole of 1-octen-3-ol bound per pentasaccharide repeating unit. Unfortunately, the number of flavour compounds, which can be studied with this method, is limited due to their low water solubility and their low UV absorption. 相似文献
58.
Romain Chauveau Georges Grévillot Stéphanie Marsteau Cécile Vallières 《Chemical Engineering Research and Design》2013
Modelling of activated carbon cartridges is essential in personal protective equipments against toxic gases in order to know the duration of protection. The linear driving force model seems to be more adapted than the actual Wheeler–Jonas model because it has more physical significance. The difficulty is that the mass transfer coefficient can not be calculated a priori. Values of the LDF mass transfer coefficient are disseminated in the literature and thus there is no overview of the range and variations with different adsorbents, adsorbates and concentrations. The object of this paper is thus twofold: obtaining values of the mass transfer coefficient at different concentrations and adsorbates in order to have a comprehensive view of variations and appreciating the validity of the LDF constant pattern model. 相似文献
59.
Philippe Colomban Hellène Courret François Romain Gwenaël Gouadec Daniel Michel 《Journal of the American Ceramic Society》2000,83(12):2974-2982
Monoclinic and hexagonal forms of celsians (BaAl2 Si2 O8 ) were synthesized by hydrolysis–polycondensation of Si/Al alkoxide mixtures. Dilatometry, Raman scattering, IR absorption, and X-ray diffraction techniques were used to identify various hexacelsian phases and their conversion into the monoclinic phase as a function of thermal treatments and doping. Emphasis is given to the relationship between the shrinkage behavior and the static and dynamic short-range disorders in the XO4 tetrahedra (X = Si/Al) arrangement. The α hexagonal phase exhibits a well-defined α–βHT transition at about 300°C but a statically disorderedβSD form, which does not vary very much with temperature and is very similar to the βHT form obtained below 300°C for some materials. This statically disordered phase is preferentially observed for fast-sintered lithium-free compositions and transforms gradually in the ordered form by annealing above 1100°C. Such stabilization of the high-temperature phase by the static disorder arising from the peculiar synthesis through alkoxide hydrolysis and the gel route, which freeze the dynamic disorder of gel-forming entities in a static disorder at the gelation step, is discussed in the light of previously observed cases. The thermal expansion behavior is very sensitive to the synthesis conditions, doping, and thermal treatments. The ordered α phase is more easily achieved with lithium-doped compositions, but lithium addition shifts the hexagonal-to-monoclinic phase transformation onset toward lower temperatures and promotes complete transformation with thermal annealing. 相似文献
60.