5 resultados para Defect introduction and removal process
em Duke University
Resumo:
We demonstrate that interferometric lithography provides a fast, simple approach to the production of patterns in self-assembled monolayers (SAMs) with high resolution over square centimeter areas. As a proof of principle, two-beam interference patterns, formed using light from a frequency-doubled argon ion laser (244 nm), were used to pattern methyl-terminated SAMs on gold, facilitating the introduction of hydroxyl-terminated adsorbates and yielding patterns of surface free energy with a pitch of ca. 200 nm. The photopatterning of SAMs on Pd has been demonstrated for the first time, with interferometric exposure yielding patterns of surface free energy with similar features sizes to those obtained on gold. Gold nanostructures were formed by exposing SAMs to UV interference patterns and then immersing the samples in an ethanolic solution of mercaptoethylamine, which etched the metal substrate in exposed areas while unoxidized thiols acted as a resist and protected the metal from dissolution. Macroscopically extended gold nanowires were fabricated using single exposures and arrays of 66 nm gold dots at 180 nm centers were formed using orthogonal exposures in a fast, simple process. Exposure of oligo(ethylene glycol)-terminated SAMs to UV light caused photodegradation of the protein-resistant tail groups in a substrate-independent process. In contrast to many protein patterning methods, which utilize multiple steps to control surface binding, this single step process introduced aldehyde functional groups to the SAM surface at exposures as low as 0.3 J cm(-2), significantly less than the exposure required for oxidation of the thiol headgroup. Although interferometric methods rely upon a continuous gradient of exposure, it was possible to fabricate well-defined protein nanostructures by the introduction of aldehyde groups and removal of protein resistance in nanoscopic regions. Macroscopically extended, nanostructured assemblies of streptavidin were formed. Retention of functionality in the patterned materials was demonstrated by binding of biotinylated proteins.
Resumo:
The various contributions to this book have documented how NAFTA-inspired firm strategies are changing the geography of apparel production in North America. The authors show in myriad ways how companies at different positions along the apparel commodity chain are responding to the new institutional and regulatory environment that NAFTA creates. By making it easier for U.S. companies to take advantage of Mexico as a nearby low-cost site for export-oriented apparel production, NAFTA is deepening the regional division of labor within North America, and this process has consequences for firms and workers in each of the signatory countries. In the introduction to this book we alluded to the obvious implications of shifting investment and trade patterns in the North American apparel industry for employment in the different countries. In this concluding chapter we focus on Mexico in the NAFTA era, specifically the extent to which Mexico's role in the North American economy facilitates or inhibits its economic development. W e begin with a discussion of the contemporary debate about Mexico's development, which turns on the question of how to assess the implications of Mexico's rapid and pro-found process of economic reform. Second, we focus on the textile and apparel industries as sectors that have been significantly affected by changes in regulatory environments at both the global and regional levels. Third, we examine the evidence regarding Mexico's NAFTA-era export dynamism, and in particular we emphasize the importance of interfirm networks, both for making sense of Mexico's meteoric rise among apparel exporters and for evaluating the implications of this dynamism for development. Fourth, we turn to a consideration of the national political-economic environment that shapes developmental outcomes for all Mexicans. Although regional disparities within Mexico are profound, aspects of government policy, such as management of the national currency, and characteristics of the institutional environment, such as industrial relations, have nationwide effects, and critics of NAFTA charge that these factors are contributing to a process of economic and social polarization that is ever more evident (Morales 1999; Dussel Peters 2000). Finally, we suggest that the mixed consequences of Mexico's NAFTA-era growth can be taken as emblematic of the contradictions that the process of globalization poses for economic and social development. The anti-sweatshop campaign in North America is one example of transnational or crossborder movements that are emerging to address the negative consequences of this process. In bringing attention to the problem of sweatshop production in North America, activists are developing strategies that rely on a network logic that is not dissimilar to the approaches reflected in the various chapters of this book. © 2009 by Temple University Press. All rights reserved.
Resumo:
As indicated by several recent studies, magnetic susceptibility of the brain is influenced mainly by myelin in the white matter and by iron deposits in the deep nuclei. Myelination and iron deposition in the brain evolve both spatially and temporally. This evolution reflects an important characteristic of normal brain development and ageing. In this study, we assessed the changes of regional susceptibility in the human brain in vivo by examining the developmental and ageing process from 1 to 83 years of age. The evolution of magnetic susceptibility over this lifespan was found to display differential trajectories between the gray and the white matter. In both cortical and subcortical white matter, an initial decrease followed by a subsequent increase in magnetic susceptibility was observed, which could be fitted by a Poisson curve. In the gray matter, including the cortical gray matter and the iron-rich deep nuclei, magnetic susceptibility displayed a monotonic increase that can be described by an exponential growth. The rate of change varied according to functional and anatomical regions of the brain. For the brain nuclei, the age-related changes of susceptibility were in good agreement with the findings from R2* measurement. Our results suggest that magnetic susceptibility may provide valuable information regarding the spatial and temporal patterns of brain myelination and iron deposition during brain maturation and ageing. © 2013 Wiley Periodicals, Inc.
Resumo:
*Designated as an exemplary master's project for 2015-16*
This paper examines how contemporary literature contributes to the discussion of punitory justice. It uses close analysis of three contemporary novels, Margaret Atwood’s The Heart Goes Last, Hillary Jordan’s When She Woke, and Joyce Carol Oates’s Carthage, to deconstruct different conceptions of punitory justice. This analysis is framed and supported by relevant social science research on the concept of punitivity within criminal justice. Each section examines punitory justice at three levels: macro, where media messages and the predominant social conversation reside; meso, which involves penal policy and judicial process; and micro, which encompasses personal attitudes towards criminal justice. The first two chapters evaluate works by Atwood and Jordan, examining how their dystopian schemas of justice shed light on top-down and bottom-up processes of punitory justice in the real world. The third chapter uses a more realistic novel, Oates’s Carthage, to examine the ontological nature of punitory justice. It explores a variety of factors that give rise to and legitimize punitory justice, both at the personal level and within a broader cultural consensus. This chapter also discusses how both victim and perpetrator can come to stand in as metaphors to both represent and distract from broader social issues. As a whole, analysis of these three novels illuminate how current and common conceptualizations of justice have little to do with the actual act of transgression itself. Instead, justice emerges as a set of specific, conditioned responses to perceived threats, mediated by complex social, cultural, and emotive forces.
Resumo:
Although cell cycle control is an ancient, conserved, and essential process, some core animal and fungal cell cycle regulators share no more sequence identity than non-homologous proteins. Here, we show that evolution along the fungal lineage was punctuated by the early acquisition and entrainment of the SBF transcription factor through horizontal gene transfer. Cell cycle evolution in the fungal ancestor then proceeded through a hybrid network containing both SBF and its ancestral animal counterpart E2F, which is still maintained in many basal fungi. We hypothesize that a virally-derived SBF may have initially hijacked cell cycle control by activating transcription via the cis-regulatory elements targeted by the ancestral cell cycle regulator E2F, much like extant viral oncogenes. Consistent with this hypothesis, we show that SBF can regulate promoters with E2F binding sites in budding yeast.