Refractory high-entropy alloys (RHEAs) are designed for high elevated-temperature strength, with both edge and screw dislocations playing an important role for plastic deformation. However, they can also display a significant energetic driving force for chemical short-range ordering (SRO). Here, we investigate mechanisms underlying the mobilities of screw and edge dislocations in the body-centered cubic MoNbTaW RHEA over a wide temperature range using extensive molecular dynamics simulations based on a highly-accurate machine-learning interatomic potential. Further, we specifically evaluate how these mechanisms are affected by the presence of SRO. The mobility of edge dislocations is found to be enhanced by the presence of SRO, whereas the rate of double-kink nucleation in the motion of screw dislocations is reduced, although this influence of SRO appears to be attenuated at increasing temperature. Independent of the presence of SRO, a cross-slip locking mechanism is observed for the motion of screws, which provides for extra strengthening for refractory high-entropy alloy system.
Experimental results show that chaotic and hyperchaotic systems can be synchronized by impulses sampled from one or two state variables. In this paper, we study the conditions under which chaotic and hyperchaotic systems can be synchronized by impulses sampled from a part of their state variables. By calculating the Lyapunov exponents of variational synchronization error systems, we show that this kind of impulsive synchronization can be applied to almost all hyperchaotic systems. We also study the selective synchronization of chaotic systems. In a selective synchronization scheme, the synchronizing signal is chosen in the time periods when the Lyapunov exponents of variational synchronization error systems are negative. Since only driving signals during the time periods when synchronization error can be reduced are applied to reduce the synchronization error, and no signal is applied during the time periods when synchronization error can be increased, selective synchronization scheme can be used to achieve synchronization even in the case when continuous synchronization schemes fail to work.
A continuous rod of porous poly(glycidyl methacrylate-co-ethylene dimethacrylate) has been prepared by a free radical polymerization within the confines of a 300 x 8 mm I.D. chromatographic column. The epoxide groups of the rod have been modified by a reaction with diethylamine that affords ionizable functionalities required for the ion-exchange chromatographic mode. The properties of this rod column have been characterized and the column has been used successfully for the chromatographic separation of proteins. The column exhibits a dynamic capacity that exceeds 300 mg at a flow velocity of 200 cm/min. An excellent selectivity allows the separation of up to 300 mg of a protein mixture in a single run.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemical synthesis and structure proof of a stereoregular linear mannan, poly[.alpha.-(1->6')-anhydro-D-mannopyranose]Jean Frechet and Conrad SchuerchCite this: J. Am. Chem. Soc. 1969, 91, 5, 1161–1164Publication Date (Print):February 1, 1969Publication History Published online1 May 2002Published inissue 1 February 1969https://pubs.acs.org/doi/10.1021/ja01033a021https://doi.org/10.1021/ja01033a021research-articleACS PublicationsRequest reuse permissionsArticle Views199Altmetric-Citations59LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Abstract Passivity is perhaps the most basic concept in circuit theory. Unfortunately, the existing definitions of passivity are too restrictive and often contradict one another. In this paper, a new passivity definition is proposed which is applicable to all n ‐port and ( n + 1)‐terminal devices—including time‐varying, non‐linear , and distributed circuit elements. This definition generalizes and reconciles several recent conflicting definitions.
Based on a simple circuit model of a tunneling phase logic (TPL) element that is driven by a sinusoidal voltage source and biased by a DC voltage source, we present simulations of operations in cellular nonlinear networks (CNN) that could potentially be used to perform general computations in 2D arrays of simple, locally connected nanoscale devices. Some examples are presented to demonstrate the image computation capability of TPL–CNN. In particular, we use a simple 2D TPL–CNN structure to perform edge detection, image enhancement and image segmentation. Some cellular automata (CA)-like behaviors of our 2D TPL-CNN are also presented.
In order to achieve significantly reduced power consumption, the transistor operating voltage needs to be reduced. To do this, a tunneling based transistor needs to rely on the density of states turn-on. Current can only flow when the conduction and valence bands overlap. If the band edges are ideal, one might expect an infinitely sharp turn on when the band edges overlap. Surprisingly, in a typical 3d bulk TFET, the nature of the turn on is actually quadratic in the gate voltage. Nevertheless, it is possible improve this if dimensionality is reduced. Consequently, we explored the nature of the band overlap for the various dimensionalities. We find that a 2d-2d pn junction brings us significantly closer to an ideal step function. Confining each side of the pn junction will also significantly increase the on state conductivity at low voltages.
