Browsing by Subject "DENSITY"

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Open Access
Boom and Bust: The Effect of Entrepreneurial Inertia on Organizational Populations
(Advances in Strategic Management, 2006) Ruef, M
Although recent public attention has focused on boom-and-bust cycles in industries and financial markets, organizational theorists have made only limited contributions to our understanding of this issue. In this chapter, I argue that a distinctive strategic insight into the mechanisms generating boom-and-bust cycles arises from a focus on entrepreneurial inertia - the lag time exhibited by organizational founders or investors entering a market niche. While popular perceptions of boom-and-bust cycles emphasize the deleterious effect of hasty entrants or overvaluation, I suggest instead that slow, methodical entries into an organizational population or market may pose far greater threats to niche stability. This proposition is explored analytically, considering the development of U.S. medical schools since the mid-18th century. © 2006 Elsevier Ltd. All rights reserved.
Open Access
Importance of diameter control on selective synthesis of semiconducting single-walled carbon nanotubes.
(ACS nano, 2014-08-11) Li, Jinghua; Ke, Chung-Ting; Liu, Kaihui; Li, Pan; Liang, Sihang; Finkelstein, Gleb; Wang, Feng; Liu, Jie
The coexistence of semiconducting and metallic single-walled carbon nanotubes (SWNTs) during synthesis is one of the major bottlenecks that prevent their broad application for the next-generation nanoelectronics. Herein, we present more understanding and demonstration of the growth of highly enriched semiconducting SWNTs (s-SWNTs) with a narrow diameter distribution. An important fact discovered in our experiments is that the selective elimination of metallic SWNTs (m-SWNTs) from the mixed arrays grown on quartz is diameter-dependent. Our method emphasizes controlling the diameter distribution of SWNTs in a narrow range where m-SWNTs can be effectively and selectively etched during growth. In order to achieve narrow diameter distribution, uniform and stable Fe-W nanoclusters were used as the catalyst precursors. About 90% of as-prepared SWNTs fall into the diameter range 2.0-3.2 nm. Electrical measurement results on individual SWNTs confirm that the selectivity of s-SWNTs is ∼95%. The present study provides an effective strategy for increasing the purity of s-SWNTs via controlling the diameter distribution of SWNTs and adjusting the etchant concentration. Furthermore, by carefully comparing the chirality distributions of Fe-W-catalyzed and Fe-catalyzed SWNTs under different water vapor concentrations, the relationship between the diameter-dependent and electronic-type-dependent etching mechanisms was investigated.