Here we provide evidence that the formation of PuO2 nanoparticles from oxidized PuVI under alkaline conditions proceeds through the formation of an intermediate PuV solid phase, similar to NH4PuO2CO3, which is stable over a period of several months. For the first time, state‐of‐the‐art experiments at Pu M4 and at L3 absorption edges combined with theoretical calculations unambiguously allow to determine the oxidation state and the local structure of this intermediate phase. 相似文献
Viruses are normally defined as pathogens and have a bad reputation because of pandemics such as Influenza, HIV/AIDS, Ebola, and SARS. Most viruses are, however, not enemies or killers but play important roles in the origin, development and maintenance of life of all species on our planet. This is new information we learnt by new technologies such as sequencing. Viruses are the most successful species on Earth, they are ubiquitous, in the oceans, in our environment, in animals, plants, bacteria, up in the air, perhaps even in the universe, within our body and even as part of our genomes. They influence our health, our well‐being, mental properties, our gut microbiota including obesity, and may help to cope with multi‐drug‐resistant bacteria. There the phages, viruses of bacteria, raise hopes. Viruses built our immunity: viruses protect against viruses. We do not have to lay eggs – thanks to viruses! They are the drivers of evolution and adaptation to environmental changes, also e. g. in plankton. The success story of viruses started about 3.5 billion years ago when life began. Newly discovered giant viruses are almost bacteria in their composition, suggesting that the borderline between dead matter and life is continuous. There are many open questions – how did life begin, is there life on exoplanets, how to find it? Are virus‐like elements, viroids, important for the origin of life? Will viruses eliminate mankind [1]? 相似文献
The synthesis, structural, and spectral characterization as well as a theoretical study of a family of alkaline‐earth‐metal acetylides provides insights into synthetic access and the structural and bonding characteristics of this group of highly reactive compounds. Based on our earlier communication that reported unusual geometry for a family of triphenylsilyl‐substituted alkaline‐earth‐metal acetylides, we herein present our studies on an expanded family of target derivatives, providing experimental and theoretical data to offer new insights into the intensively debated theme of structural chemistry in heavy alkaline‐earth‐metal chemistry. 相似文献
A new family in town! Treatment of a rare‐earth metal (Ln) and either a potential divalent rare‐earth metal (Ln′) or an alkaline earth metal (Ae) with 2,6‐diphenylphenol (HOdpp) at elevated temperatures (200–250 °C) afforded heterobimetallic aryloxo complexes (see figure). Both a charge‐separated species, [(Ln′/Ae)2(Odpp)3][Ln(Odpp)4], and a neutral species, [AeEu(Odpp)4], were obtained and crystallographically characterised.
A novel amino-reactive fluorescent label is presented that is based on a yellow daylight chromophore and fluorophore. Its absorption band is wide and peaks at 431 nm in water solution, thus well matching the lines of either the 375-nm and the 431-nm diode lasers and of many frequency-variable dye lasers. When conjugated to bovine serum albumin (BSA), the fluorescence peaks at 501 nm with a quantum yield of 0.21. Its large Stokes' shift of 70 nm facilitates the discrimination of undesired excitation light which is particularly important for sensitive detection in miniaturized separation techniques such as microchip capillary electrophoresis (MCE). Unlike several other fluorophores, the fluorescence intensity of the new label is independent of pH over a broad range (3 to 9). The applicability of the label is demonstrated by labeling the amino acid lysine and the 66 kD protein BSA, and by separating BSA from the free label via MCE within 90 s. The limit of detection is in the order of 12 nM at an optically active path length of 20 µm.
Let H⊆Zd be a positive semigroup generated by A⊆H, and let K[H] be the associated semigroup ring over a field K. We investigate heredity of the Cohen-Macaulay property from K[H] to both its A-Newton graded ring and to its face rings. We show by example that neither one inherits in general the Cohen-Macaulay property. On the positive side, we show that for every H there exist generating sets A for which the Newton graduation preserves Cohen-Macaulayness. This gives an elementary proof for an important vanishing result on A-hypergeometric Euler-Koszul homology. As a tool for our investigations we develop an algorithm to compute algorithmically the Newton filtration on a toric ring. 相似文献
The ellipticity of boundary value problems on a smooth manifold with boundary relies on a two-component principal symbolic
structure , consisting of interior and boundary symbols. In the case of a smooth edge on manifolds with boundary, we have a third symbolic
component, namely, the edge symbol , referring to extra conditions on the edge, analogously as boundary conditions. Apart from such conditions ‘in integral form’
there may exist singular trace conditions, investigated in Kapanadze et al., Internal Equations and Operator Theory, 61, 241–279,
2008 on ‘closed’ manifolds with edge. Here, we concentrate on the phenomena in combination with boundary conditions and edge
problem. 相似文献
ABSTRACTWe present a method to perform improved measurements of the effects of chemical variability on physical properties of single-crystal samples in the diamond-anvil cell by employing a multi-sample approach. By customizing the sizes and shapes of the samples using a focused ion beam machine the simultaneous loading of relatively large crystals into a single sample chamber becomes feasible. To illustrate the potential of this approach, elastic properties of four single crystals of ringwoodite with different chemical compositions have been measured at high pressure. Our results suggest that the multi-sample approach allows for the quantification of small effects of chemical variations, such as iron and hydrogen incorporation, on physical properties. Furthermore, we discuss the possibility of using the multi-sample approach to load several crystals with different crystallographic orientations of the same material into one sample chamber in order to map out the direction dependence of anisotropic physical properties. 相似文献
Monatshefte für Mathematik - We define a map from tilings of surfaces with marked points to strand diagrams, generalising Scott’s construction for the case of triangulations of polygons.... 相似文献