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91.
Luca Pasquini Elsa Callini Matteo Brighi Federico Boscherini Amelia Montone Torben R. Jensen Chiara Maurizio Marco Vittori Antisari Ennio Bonetti 《Journal of nanoparticle research》2011,13(11):5727-5737
We report on the hydrogen storage behaviour of Mg nanoparticles (NPs) (size range 100 nm–1 μm) with metal-oxide core–shell
morphology synthesized by inert gas condensation and decorated by transition metal (TM) (Pd or Ti) clusters via in situ vacuum
deposition. The structure and morphology of the as-prepared and hydrogenated NPs is studied by electron microscopy, X-ray
diffraction including in situ experiments and X-ray absorption spectroscopy, in order to investigate the relationships with
the hydrogen storage kinetics measured by the volumetric Sieverts method. With both Pd and Ti, the decoration deeply improves
the hydrogen sorption properties: previously inert NPs exhibit complete hydrogenation with fast transformation kinetics, good
stability and reversible gravimetric capacity that can attain 6 wt%. In the case of Pd-decoration, the occurrence of Mg–Pd
alloying is observed at high temperatures and in dependence of the hydrogen pressure conditions. These structural transformations
modify both the kinetics and thermodynamics of hydride formation, while Ti-decoration has an effect only on the kinetics.
The experimental results are discussed in relation with key issues such as the amount of decoration, the heat of mixing between
TM and Mg and the binding energy between TM and hydrogen. 相似文献
92.
93.
94.
Chiara B. Vicentini Manuela Mazzanti Carlo F. Morelli Maurizio Manfrini 《Journal of heterocyclic chemistry》2000,37(1):175-180
Ethyl 2-amino-3-methoxycarbonyl-4-oxo-2-pentenoate (3) reacts with hydroxylamine or hydrazines to give isoxazole and pyrazole ortho-dicarboxylic acid esters 4 and 5, respectively. Partial hydrolysis of diesters 4 and 5 afforded the corresponding dicarboxylic acid monoesters 6 and 7. Amidation of the intermediate acid chlorides 8,9 followed by hydrolysis of 4-methylesters 10, 11 gave the title compounds 1 and 2, respectively. 相似文献
95.
96.
Giampio Bracchi Chiara Francalanci 《Computational & Mathematical Organization Theory》1997,3(3):173-198
This paper proposes a formal model of information processing inorganizations. The model takes a process view of organizations and includesboth structural and IS features of processes. Two structural properties areconsidered, networking and parallelism. Information systems are representedin terms of quantity of information used and level of informationcustomization allowed. Process performance is measured in terms of totalinformation processing capacity and flexibility afforded by a process. Therelationship between structural and information system choices and processperformance is studied by simulating the model for a range of values. Thepaper derives a set of propositions describing the independent and combinedimpact of structural and information system choices on performance. The results suggest the predominance of networking over parallelism and ofinformation customization over information quantity in determininginformation processing capacity. They also show a negative effect ofnetworking on process flexibility and an amplifying effect of networking onthe benefits of information customization. Overall, the findings validatethe interdependence between structural and information system variables indetermining process performance. 相似文献
97.
The total and the sharp character of orthodox quantum logic has been put in question in different contexts. This paper presents the basic ideas for a unified approach to partial and unsharp forms of quantum logic. We prove a completeness theorem for some partial logics based on orthoalgebras and orthomodular posets. We introduce the notion of unsharp orthoalgebra and of generalized MV algebra. The class of all effects of any Hilbert space gives rise to particular examples of these structures. Finally, we investigate the relationship between unsharp orthoalgebras, generalized MV algebras, and orthomodular lattices. 相似文献
98.
99.
Paola Benzi Elena Bottizzo Chiara Demaria Nicoletta Rizzi 《Journal of Chemical Sciences》2007,119(6):631-635
YBa2Cu3Ox (Y-123) and Bi2Sr2Ca1Cu2Ox (Bi-2212) films on various substrates have been prepared by Metal-Organic Deposition starting from different metallorganic
fluorine-free compounds and using a very simple instrumentation. The processing conditions include a rapid pyrolysis step
in air and an annealing step in oxygen for Y-123 and in air for Bi-2212. The films obtained have been characterized by X-ray
diffraction (XRD) and the formation of a superconducting phase of Y-123 or Bi-2212 was confirmed measuring the critical temperature
(T
c) with Ac-susceptibility and resistive measurements. Microstructure and final cationic ratios have been studied by scanning
electron microscopy (SEM) and energy dispersive spectroscopy (EDS). 相似文献
100.
A groupG is said to be (2,3)-generated if it can be generated by two elements of respective orders 2 and 3. The class of these groups has recently received a lot of attention by several authors: a brief survey of the results in this area is given in the introduction. In this paper we show that, ifR is a ring generated by one element of finite multiplicative order, then the analogues of classical groups overR are (2,3)-generated, provided that their rank is sufficiently large. Our lower bound for the rank improves previous results. 相似文献