Single-walled carbon nanotubes (SWCNTs) are attracting increasing attention as an ideal material for high-performance electronics through the preparation of arrays of purely semiconducting SWCNTs. Despite significant progress in the controlled synthesis of SWCNTs, their growth mechanism remains unclear due to difficulties in analyzing the time-resolved growth of individual SWCNTs under practical growth conditions. Here we present a method for tracing the diverse growth profiles of individual SWCNTs by embedding digitally coded isotope labels. Raman mapping showed that, after various incubation times, SWCNTs elongated monotonically until their abrupt termination. Ex situ analysis offered an opportunity to capture rare chirality changes along the SWCNTs, which resulted in sudden acceleration/deceleration of the growth rate. Dependence on growth parameters, such as temperature and carbon concentration, was also traced along individual SWCNTs, which could provide clues to chirality control. Systematic growth studies with a variety of catalysts and conditions, which combine the presented method with other characterization techniques, will lead to further understanding and control of chirality, length, and density of SWCNTs.

In order to achieve the chirality-specific growth of single-walled carbon nanotubes (SWCNTs), it is crucial to understand the growth mechanism. Even though many molecular dynamics (MD) simulations have been employed to analyze the SWCNT growth mechanism, it has been difficult to discuss the chirality determining kinetics because of the defects remaining on the SWCNTs grown in simulations. In this study, we demonstrate MD simulations of defect-free SWCNTs, that is, chirality definable SWCNTs, under the optimized carbon supply rate and temperature. The chiralities of the SWCNTs were assigned as (14,1), (15,2), and (9,0), indicating the preference of near-zigzag and pure-zigzag SWCNTs. The SWCNTs contained at least one complete row of defect-free walls consisting of only hexagons. The near-zigzag SWCNTs grew via a kink-running process, in which bond formation between a carbon atom at a kink and a neighboring carbon chain led to formation of a hexagon with a new kink at the SWCNT edge. Defects including pentagons and heptagons were sometimes formed but effectively healed into hexagons on metal surfaces. The pure-zigzag SWCNTs grew by the kink-running and the hexagon nucleation processes. In addition, chirality change events along SWCNTs with incorporation of pentagon–heptagon pair defects were observed in the MD simulations. Here, pentagons and heptagons were frequently observed as adjacent pairs, resulting in (n,m) chirality changes by (±1,0), (0,±1), (1,–1), or (−1,1).

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use of synchronized measurement keeping the stability of real Abstract-Since the aspect of instability phenomena during power systems [ 1]- [4]. I n particular, the synchronized phasors midtcrm is cumplicated, the stability analysis is significant in over wide-area, which have implication to the stability, can be order to keep the powcr system stable. Synchronized phasor measured by using [he PMU, angles obtained by the PMU (Phasor Measurement Unit) provide under this background, we propose a midterm stability the effective information for evaluating the stability of B bulk power system. This paper prnposcs a midterm stability evaluation evaluation method based On the synchronized phasor measurements for the purpose of grasping the aspect of the phasor measurements. Clustering and aggregating the power step-out phenomenon of the bulk power system and then method of the wide-area power system by using the synchronized system to some coherent generator groups, the stability margin of appropriately executing the protection. The each coherent group is quantitatively evaluated on the basis of the effectiveness of the proposed through the one machine and infinite bus system. The midterm stability of B experiments using a hybrid-type power system simulator. The longitudinal power system model of Japanese 60Hz systems bv the psA ,power s , ,~~~~ Analvrer), which is network model is the IEEJ (Institute of Electrical and,.~~ hybrid-type power system simulator. is practically evaluatfd using the proposed method.Electronics Japan) WEST I O-machine system 151, which is a longitudinal power system model of Japanese 60Hz systems. In this paper, the procedure of the phasor computation and stability evaluation are explained in section 11. And next, the results of the experiments are shown in section 111.Indm Terms-aggregation.coherency. DFT, midterm stability, PMU, synchronized measurement.