University of Wisconsin–Milwaukee

About: University of Wisconsin–Milwaukee is a education organization based out in Milwaukee, Wisconsin, United States. It is known for research contribution in the topics: Population & Gravitational wave. The organization has 11839 authors who have published 28034 publications receiving 936438 citations. The organization is also known as: UWM & University of Wisconsin-Milwaukee.

From e-sex to e-commerce: Web search changes

Abstract: The Web has become a worldwide source of information and a mainstream business tool. Are human information needs and searching behaviors evolving along with Web content? As part of a body of research studying this question, we have analyzed three data sets culled from more than one million queries submitted by more than 200,000 users of the Excite Web search engine, collected in September 1997, December 1999, and May 2001. This longitudinal benchmark study shows that public Web searching is evolving in certain directions. Specifically, search topics have shifted from entertainment and sex to commerce and people, but there is little change in query lengths or frequency per user. Search topics have shifted, but there is little change in user search behaviors.

Metal−Organic Framework‐Derived Nitrogen‐Doped Core‐Shell‐Structured Porous Fe/Fe3C@C Nanoboxes Supported on Graphene Sheets for Efficient Oxygen Reduction Reactions

Abstract: DOI: 10.1002/aenm.201400337 synthesis of MOFs-derived porous Fe, N-based carbon catalysts supported on NRGO sheets as ORR catalysts. Here, we report the fabrication of novel nitrogen-doped coreshell-structured porous Fe/Fe 3 C@C nanoboxes supported on RGO sheets (N-doped Fe/Fe 3 C@C/RGO) by a simple pyrolysis process using graphene oxide (GO) and PB nanocubes as precursors. Such a unique structure not only offers more active sites from both nitrogen-doped Fe/Fe 3 C@C and NRGO sheets, but also shows enhanced electrical conductivity. As a result, the hybrid exhibits much better electrocatalytic activity, long-term stability, and methanol tolerance ability than the commercial Pt/C catalyst (10% Pt on Vulcan XC-72). The fabrication process for the porous N-doped Fe/Fe 3 C@C/ RGO hybrid is demonstrated in Figure 1 a. Highly uniform PB nanocubes were fi rstly synthesized using a hydrothermal method based on previous reports. [ 9a ] The obtained PB nanocubes were further dispersed in the GO solution (PB/GO) under stirring. The resulting PB/GO powders after drying at 80 °C were then annealed at 800 °C in an argon fl ow to form a core-shell-structured porous N-doped Fe/Fe 3 C@C/RGO hybrid. During this process, the continuous decomposition of PB nanocubes was accompanied by releasing nitrogen-containing gases, [ 11 ] which resulted in the formation of a porous structure accompanied with carbide reactions according to the thermogravimetric analysis (TGA) results (Figure S1, Supporting Information). Simultaneously, the nitrogen-containing species contributed to the reduction of GO and nitrogen doping in both GO and carbon shells, fi nally evolving into nitrogen-doped core-shell-structured porous Fe/Fe 3 C@C/RGO hybrids. The PB nanocubes not only act as templates/precursors, but also provide nitrogen sources for the formation of N-doped Fe/Fe 3 C@C and NRGO. Field-emission scanning electron microscopy (FESEM) images show that uniform PB nanocubes with an edge length of about 500 nm are obtained without any aggregation (Figure 1 b). An enlarged image (inset of Figure 1 b) reveals the very smooth surface over a single box. After the thermal treatment, the PB nanocubes are converted to porous N-doped Fe/Fe 3 C@C nanoboxes with a side length of around 300–400 nm (Figure 1 c). The cubic structure still remained, although its size decreased a little due to the decomposition and shrinkage during the annealing process. [ 12 ] This suggests that the PB nanocubes served as both a template and a self-sacrifi cing precursor for the formation of porous nanoboxes, which are composed of numerous Developing catalytic materials with high activity for oxygen reduction reaction (ORR) is of great signifi cance for commercial fuel cell applications. [ 1 ] Although Pt-based materials are known as the most effi cient ORR catalysts, [ 2 ] they still suffer from several serious problems, including high cost, low abundance, weak durability, crossover effect and CO poisoning; [ 3 ]

Shewanella oneidensis MR-1 nanowires are outer membrane and periplasmic extensions of the extracellular electron transport components

Abstract: Bacterial nanowires offer an extracellular electron transport (EET) pathway for linking the respiratory chain of bacteria to external surfaces, including oxidized metals in the environment and engineered electrodes in renewable energy devices. Despite the global, environmental, and technological consequences of this biotic-abiotic interaction, the composition, physiological relevance, and electron transport mechanisms of bacterial nanowires remain unclear. We report, to our knowledge, the first in vivo observations of the formation and respiratory impact of nanowires in the model metal-reducing microbe Shewanella oneidensis MR-1. Live fluorescence measurements, immunolabeling, and quantitative gene expression analysis point to S. oneidensis MR-1 nanowires as extensions of the outer membrane and periplasm that include the multiheme cytochromes responsible for EET, rather than pilin-based structures as previously thought. These membrane extensions are associated with outer membrane vesicles, structures ubiquitous in Gram-negative bacteria, and are consistent with bacterial nanowires that mediate long-range EET by the previously proposed multistep redox hopping mechanism. Redox-functionalized membrane and vesicular extensions may represent a general microbial strategy for electron transport and energy distribution.

The spatialities of contentious politics

Abstract: The question of how space matters to the mobilisation, practices and trajectories of contentious politics has frequently been represented as a politics of scale. Others have focused on place and networks as key spatialities of contentious politics. Yet there are multiple spatialities – scale, place, networks, positionality and mobility – that are implicated in and shape contentious politics. No one of these should be privileged: in practice, participants in contentious politics frequently draw on several at once. It is thus important to consider all of them and the complex ways in which they are co-implicated with one another, with unexpected consequences for contentious politics. This co-implication in practice, and its impact on social movements, is illustrated with the Immigrant Workers’ Freedom Ride in the United States.