University of Delaware

About: University of Delaware is a education organization based out in Newark, Delaware, United States. It is known for research contribution in the topics: Population & Catalysis. The organization has 22223 authors who have published 54810 publications receiving 2049136 citations. The organization is also known as: University of Delaware Emergency Care Unit & UD.

Wormlike Micelles Formed by Synergistic Self-Assembly in Mixtures of Anionic and Cationic Surfactants

Abstract: Self-assembly in mixtures of cationic and anionic surfactants occurs synergistically because of attractive interactions between the oppositely charged headgroups. Here, such effects are exploited to obtain highly viscoelastic fluids at low total surfactant concentration. The systems considered are mixtures of the C18-tailed anionic surfactant, sodium oleate (NaOA), and cationic surfactants from the trimethylammonium bromide family (CnTAB). In particular, mixtures of NaOA and C8TAB show remarkably high viscosities: for 3% surfactant, the zero-shear viscosity η0 peaks at ca. 1800 Pa·s for a weight ratio of 70/30 NaOA/C8TAB. The high viscosities reflect the growth of giant, entangled wormlike micelles in the solutions. Mixtures of NaOA with a shorter-chain analogue (C6TAB) have much lower viscosities, indicating a weak micellar growth and hence a weak attraction between the surfactants. On the other hand, increasing the CnTAB tail length to n = 10 or 12 leads to much stronger interactions between these surf...

Looking for Gender: Gender Roles and Behaviors Among Online Gamers

Abstract: Several hypotheses regarding the importance of gender and relationships were tested by combining a large survey dataset with unobtrusive behavioral data from 1 year of play. Consistentwithexpectations,malesplayedforachievement-orientedreasonsandweremore aggressive, especially within romantic relationships where both partners played. Female players in such relationships had higher general happiness than their male counterparts. Contrary to stereotypes and current hypotheses, it was the female players who played the most. Female players were also healthier than male players or females in the general population. The findings have implications for gender theory and communication-oriented methods in games and online research—most notably for the use of self-reported time spent, which was systematically incorrect and different by gender. doi:10.1111/j.1460-2466.2009.01453.x Female video game players now comprise 40% of all players, and women over 18 make up more of the game-playing population than do males under 17 (Top 10 IndustryFacts, 2008). Yet, studies of men and women report both genders believe that computer games are a ‘‘particularly masculine pursuit’’ (Selwyn, 2007, p. 533). Are more women ignoring social sanctions for engaging in a supposedly masculine activity? Are men avoiding feminine actions while playing? To determine the answers, we must investigate how video game players are positioning their activity in relation to their gender, and better understand their reasons for playing games at all. Past media research on gaming has found that men and women perform in, and perceive, games differently (Blumberg & Sokol, 2004), but this research has not been updated since the mass adoption of large-scale online games. Likewise, social scientific research in the area of gender roles has not examined online game play, and how it may be changing gendered definitions of game play. At the same time, research covering a wide variety of social Internet activities has found women’s uses and considerations to be different

A study of the dynamics of foam growth: Analysis of the growth of closely spaced spherical bubbles

Abstract: A mathematical analysis of bubble growth in an expanding foam is presented. The analysis is based on a cell model whereby the foam is divided into spherical microscopic unit cells of equal and constant mass, each consisting of a liquid envelope (or shell) and a concentric spherical gas bubble. Expansion occurs by diffusion of a dissolved gas from the supersaturated envelope into the bubble. This cell model is capable of describing important qualitative features of a real system of numerous bubbles growing in close proximity to one another, and is intended as the building block of a global analysis of macroscopic foam expansion. The coupled algebraic and differential equations governing the growth of a cell are derived and solved numerically. Five dimensionless parameters are identified for the case of constant temperature and pressure outside the cell, and their effects are demonstrated through computer simulations of the system. Of these parameters, surface tension and initial radius prove to be of relatively little importance in the practical cases considered. The other parameters are the thermodynamic driving force, the cell mass (inversely proportional to the number density of bubbles), and the ratio of characteristic times for mass and momentum transport.