University of Texas at Austin

About: University of Texas at Austin is a education organization based out in Austin, Texas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 94352 authors who have published 206297 publications receiving 9070052 citations. The organization is also known as: UT-Austin & UT Austin.

Molecular mechanistic origin of the toughness of natural adhesives, fibres and composites

Abstract: Natural materials are renowned for their strength and toughness1,2,3,4,5. Spider dragline silk has a breakage energy per unit weight two orders of magnitude greater than high tensile steel1,6, and is representative of many other strong natural fibres3,7,8. The abalone shell, a composite of calcium carbonate plates sandwiched between organic material, is 3,000 times more fracture resistant than a single crystal of the pure mineral4,5. The organic component, comprising just a few per cent of the composite by weight9, is thought to hold the key to nacre's fracture toughness10,11. Ceramics laminated with organic material are more fracture resistant than non-laminated ceramics11,12, but synthetic materials made of interlocking ceramic tablets bound by a few weight per cent of ordinary adhesives do not have a toughness comparable to nacre13. We believe that the key to nacre's fracture resistance resides in the polymer adhesive, and here we reveal the properties of this adhesive by using the atomic force microscope14 to stretch the organic molecules exposed on the surface of freshly cleaved nacre. The adhesive fibres elongate in a stepwise manner as folded domains or loops are pulled open. The elongation events occur for forces of a few hundred piconewtons, which are smaller than the forces of over a nanonewton required to break the polymer backbone in the threads. We suggest that this ‘modular’ elongation mechanism might prove to be quite general for conveying toughness to natural fibres and adhesives, and we predict that it might be found also in dragline silk.

Electoral Politics as a Redistributive Game

Abstract: Spatial models of electoral competition typically simplify the analysis by ignoring the question of internal constituency politics: constituencies are modeled simply as a distribution of ideal points along a set of issue dimensions. Matters related to the stability of divergent electoral coalitions have rarely been addressed. We explicitly take into account how differential rates of support by various groups in a constituency will influence candidates' campaign promises and the likelihood that stable electoral coalitions will be forged. Viewing campaign platforms as promised redistributions of welfare, we argue that the optimal strategy for risk-averse candidates will be to promise redistributions first and foremost to their reelection constituency and thereby to maintain existing political coalitions. We use evidence from the urban services literature to support our propositions.

The Strategic Context of External Network Ties: Examining the Impact of Director Appointments on Board Involvement in Strategic Decision Making

Abstract: This study examines how external network ties determine a board's ability to contribute to the strategic decision making process. Although the simple number of director appointments to other boards...

The Glass Escalator: Hidden Advantages for Men in the “Female” Professions

Abstract: This paper addresses men's underrepresentation in four predominantly female professions: nursing, elementary school teaching, librarianship, and social work. Specifically, it examines the degree to which discrimination disadvantages men in hiring and promotion decisions, the work place culture, and in interactions with clients. In-depth interviews were conducted with 99 men and women in these professions in four major U.S. cities. The interview data suggest that men do not face discrimination in these occupations; however, they do encounter prejudice from individuals outside their professions. In contrast to the experience of women who enter male-dominated professions, men generally encounter structural advantages in these occupations which tend to enhance their careers. Because men face different barriers to integrating nontraditional occupations than women face, the need for different remedies to dismantle segregation in predominantly female jobs is emphasized.

Synthesis and solid-state NMR structural characterization of 13C-labeled graphite oxide.

Abstract: The detailed chemical structure of graphite oxide (GO), a layered material prepared from graphite almost 150 years ago and a precursor to chemically modified graphenes, has not been previously resolved because of the pseudo-random chemical functionalization of each layer, as well as variations in exact composition. Carbon-13 (13C) solid-state nuclear magnetic resonance (SSNMR) spectra of GO for natural abundance 13C have poor signal-to-noise ratios. Approximately 100% 13C-labeled graphite was made and converted to 13C-labeled GO, and 13C SSNMR was used to reveal details of the chemical bonding network, including the chemical groups and their connections. Carbon-13–labeled graphite can be used to prepare chemically modified graphenes for 13C SSNMR analysis with enhanced sensitivity and for fundamental studies of 13C-labeled graphite and graphene.