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1.
Timothy Zurrer Kenneth Wong Jonathan Horlyck Emma C. Lovell Joshua Wright Nicholas M. Bedford Zhaojun Han Kang Liang Jason Scott Rose Amal 《Advanced functional materials》2021,31(9):2007624
The vast chemical and structural tunability of metal–organic frameworks (MOFs) are beginning to be harnessed as functional supports for catalytic nanoparticles spanning a range of applications. However, a lack of straightforward methods for producing nanoparticle-encapsulated MOFs as efficient heterogeneous catalysts limits their usage. Herein, a mixed-metal MOF, NiMg-MOF-74, is utilized as a template to disperse small Ni nanoclusters throughout the parent MOF. By exploiting the difference in Ni O and Mg O coordination bond strength, Ni2+ is selectively reduced to form highly dispersed Ni nanoclusters constrained by the parent MOF pore diameter, while Mg2+ remains coordinated in the framework. By varying the ratio of Ni to Mg in the parent MOF, accessible surface area and crystallinity can be tuned upon thermal treatment, influencing CO2 adsorption capacity and hydrogenation selectivity. The resulting Ni nanoclusters prove to be an active catalyst for CO2 methanation and are examined using extended X-ray absorption fine structure and X-ray photoelectron spectroscopy. By preserving a segment of the Mg2+-containing MOF framework, the composite system retains a portion of its CO2 adsorption capacity while continuing to deliver catalytic activity. The approach is thus critical for designing materials that can bridge the gap between carbon capture and CO2 utilization. 相似文献
2.
3.
M. B. Wright 《The Journal of the Operational Research Society》1989,40(2):187-192
This paper addresses a problem common to all railway networks. Given a fixed train timetable and locomotives (or other forms of traction) of various types, each train must be allocated a locomotive. This paper examines the use of stochastic algorithms for such a problem. Two types of algorithm are used—a simple ‘local improvement’ method, performed successively from randomly chosen starting points, and a ‘simulated annealing’ approach. Both are found to give considerably better results than a deterministic method in current use, and the annealing approach is probably the better stochastic method. 相似文献
4.
This paper looks at the concepts of entities, identities, identifiers and credentials, their definitions, and how they combine
to authenticate an identity to an account, or function, within a service. Credentials can be divided into several different
types on the basis of their use, origin and characteristics. In particular, types such as composite, dynamic and derived credentials
will be considered, and their applicability within an identity management system. Each credential must be managed through
its entire life cycle from initial registration, general use and suspension, to deletion. The notion of public (i.e. freely
distributable) and private (i.e. known only to you) aspects of a credential is explored. The bindings, by trusted third parties,
of identifiers and public credentials into permits and instruments of proof is explained along with the convenience, but greater
exposure, of local information. Several scenarios are analysed in terms of how different types of credentials are employed
during the authentication process. 相似文献
5.
6.
Maury Wright 《电子设计技术》2007,14(3):38-38
我去了德国慕尼黑一年两次的Electronica贸易展,最近才从这次欧洲之行返回.我很高兴地告诉大家:高速互联网接入目前在整个西欧得到了广泛使用. 相似文献
7.
Water suppression by diffusive attenuation was used to measure Brix in intact cellular tissue of apple and strawberry. Given
the signal-to-noise ratio, the correlation for apple was established without repeated acquisition, so this protocol should
also be useful for rapid, on-line measurements at low spectrometer frequencies. Water suppression by theT
1-Null method fails with cellular tissue because of the considerable variation in the longitudinal relaxation times of vacuolar
and cytoplasmic water. 相似文献
8.
Tracy Noble Ricardo Nemirovsky Cara Dimattia Tracey Wright 《International Journal of Computers for Mathematical Learning》2004,9(2):109-167
In this article, we will describe the results of a study of 6th grade students learning about the mathematics of change. The
students in this study worked with software environments for the computer and the graphing calculator that included a simulation
of a moving elevator, linked to a graph of its velocity vs. time. We will describe how the students and their teacher negotiated
the mathematical meanings of these representations, in interaction with the software and other representational tools available
in the classroom. The class developed ways of selectively attending to specific features of stacks of centimeter cubes, hand-drawn
graphs, and graphs (labeled velocity vs. time) on the computer screen. In addition, the class became adept at imagining the
motions that corresponded to various velocity vs. time graphs. In this article, we describe this development as a process
of learning to see mathematical representations of motion. The main question this article addresses is: How do students learn
to see mathematical representations in ways that are consistent with the discipline of mathematics?
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Maury Wright 《电子设计技术》2005,12(10):34-36,38,40,42
在SAN领域居首要地位的是光纤通道,InfiniBand正在计算机集群领域发展,而具有更快速特点的以太网像一位潜在的万能博士正在隐隐出现。 相似文献
10.
This paper is concerned with the mesh selection algorithm of COLSYS, a well known collocation code for solving systems of boundary value problems. COLSYS was originally designed to solve non-stiff and mildly stiff problems only. In this paper we show that its performance for solving extremely stiff problems can be considerably improved by modifying its error estimation and mesh selection algorithms. Numerical examples indicate the superiority of the modified algorithm.Dedicated to John Butcher on the occasion of his sixtieth birthday 相似文献