4,576 research outputs found

    Review of the Synergies Between Computational Modeling and Experimental Characterization of Materials Across Length Scales

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    With the increasing interplay between experimental and computational approaches at multiple length scales, new research directions are emerging in materials science and computational mechanics. Such cooperative interactions find many applications in the development, characterization and design of complex material systems. This manuscript provides a broad and comprehensive overview of recent trends where predictive modeling capabilities are developed in conjunction with experiments and advanced characterization to gain a greater insight into structure-properties relationships and study various physical phenomena and mechanisms. The focus of this review is on the intersections of multiscale materials experiments and modeling relevant to the materials mechanics community. After a general discussion on the perspective from various communities, the article focuses on the latest experimental and theoretical opportunities. Emphasis is given to the role of experiments in multiscale models, including insights into how computations can be used as discovery tools for materials engineering, rather than to "simply" support experimental work. This is illustrated by examples from several application areas on structural materials. This manuscript ends with a discussion on some problems and open scientific questions that are being explored in order to advance this relatively new field of research.Comment: 25 pages, 11 figures, review article accepted for publication in J. Mater. Sc

    Processing Conditions for Ultrastable Surfactant-Free Nanoparticle Stabilized Foams

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    Foams, which are mixtures of gas and either a liquid or solid, are important to many applications, from consumer products to industrial processes. Stabilizing the liquid/gas interface against coalescence is key to the performance of foams. Typically, molecular surfactants (surface active agents) are used for interfacial stability, but adsorption/desorption of surfactant can diminish foam performance. We investigated the use of solid nanoparticles, rather than surfactants, as stabilizers. Fumed silica nanoparticles of varying surface chemistry, ranging from hydrophobic to hydrophilic, were suspended at 1% (w/w) and agitated in solutions of water and ethanol. Foam (gas in liquid), suspensions, and inverse foam (“liquid marbles”) structures formed during agitation; these materials were classified into a structure map as a function of processing conditions. We found the agitation intensity, solution chemistry, and surface chemistry of the fumed silica nanoparticles had a profound effect on the final structure and that there was an envelope of optimal processing conditions for producing foam. Coalescence was mitigated for 49 days as of writing this abstract. Superior stability arises from the large energy necessary to remove particles with suitable chemistry from an interface. Thus, both the energy input and system chemistry are central to designing ultrastable foams.https://engagedscholarship.csuohio.edu/u_poster_2015/1044/thumbnail.jp

    Processing Conditions for Ultrastable Surfactant-Free Nanoparticle Stabilized Foams

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    Foams, which are mixtures of gas and either a liquid or solid, are important to many applications, from consumer products to industrial processes. Stabilizing the liquid/gas interface against coalescence is key to the performance of foams. Typically, molecular surfactants (surface active agents) are used for interfacial stability, but adsorption/desorption of surfactant can diminish foam performance. We investigated the use of solid nanoparticles, rather than surfactants, as stabilizers. Fumed silica nanoparticles of varying surface chemistry, ranging from hydrophobic to hydrophilic, were suspended at 1% (w/w) and agitated in solutions of water and ethanol. Foam (gas in liquid), suspensions, and inverse foam (“liquid marbles”) structures formed during agitation; these materials were classified into a structure map as a function of processing conditions. We found the agitation intensity, solution chemistry, and surface chemistry of the fumed silica nanoparticles had a profound effect on the final structure and that there was an envelope of optimal processing conditions for producing foam. Coalescence was mitigated for 49 days as of writing this abstract. Superior stability arises from the large energy necessary to remove particles with suitable chemistry from an interface. Thus, both the energy input and system chemistry are central to designing ultrastable foams.https://engagedscholarship.csuohio.edu/u_poster_2015/1044/thumbnail.jp

    The Determinants of Within Metropolitan Immigrant Moves

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    While the role of immigration and neighborhood change has been studied since the days of the Chicago School of Sociology, recent restrictions to immigration in concert with state and local initiatives to both enforce immigration policy or welcome immigrants raises new questions about neighborhood sorting within metropolitan areas. Policy makers are interested in recruiting high skilled and wealthy immigrants to attract investment and create jobs for native-born citizens. Some have endorsed welcoming immigrants as a solution to regional economic development and to stabilize high poverty urban neighborhoods. Are these immigrant recruitment policies realistic given existing patterns of immigrant housing location choice within metropolitan areas? This study will investigate the determinants of immigrant concentration within metropolitan regions such as presence of immigrant serving organizations, tract level poverty, median rents, education, language ability, minority businesses and other variables. In order to answer this question, we analyze normalized Census data from the National Neighborhood Change Database using standard panel data techniques. Findings show that immigrants appear to be interested in choosing tracts with lower median gross rents, and increasing rental opportunities. They are also moving into new areas that immigrants had not been living in the previous decade. Immigrant entrepreneurship is also important for the attraction on immigrants. Local governments that wish to attract immigrants need to provide quality education and affordable rents

    A monoclinic polymorph of (1E,5E)-1,5-bis­(2-hy­droxy­benzyl­idene)thio­carbono­hydrazide

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    The title compound, C15H14N4O2S, is a derivative of thio­ureadihydrazide. In contrast to the previously reported polymorph (ortho­rhom­bic, space group Pbca, Z = 8), the current study revealed monoclinic symmetry (space group P21/n, Z = 4). The mol­ecule shows non-crystallographic C 2 as well as approximate C s symmetry. Intra­molecular bifurcated O—H⋯(N,S) hydrogen bonds, are present. In the crystal, inter­molecular N—H⋯S hydrogen bonds and C—H⋯π contacts connect the mol­ecules into undulating chains along the b axis. The shortest centroid–centroid distance between two aromatic systems is 4.5285 (12) Å

    P1: Salt Concentration and pH Affect the Size of Elastin-Like Polypeptide Nanoparticles

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    The transport of therapeutic drugs to specific tissues in the body can be accomplished using nanoparticles that encapsulate the drugs. Elastin-like polypeptides (ELP) is a class of materials that can reversibly form such nanoparticles in response to environmental cues. FLPs transition from soluble compounds to a phase separated system under particular solution conditions and have been used to produce temperature responsive surfactants. When these ELP surfactants are above their transition temperature, they spontaneously form energetically stable spherical micelles. When the temperature drops below the transition temperature, the micelles break apart and the ELP goes into solution. The size of these micelles can change depending on the solution conditions, including pH and salt concentration. We studied how the size of the micelles are affected by these solution conditions by using dynamic light scattering to determine the diameter of the ELP micelles. When the salt concentration increased, we found that there was a region of constant size followed by a region of linear increase in diameter. Following the linear region, there is a jump in micelle size. As the pH of the solution increased from neutral pH, the diameter drastically increased. As pH decreased from neutral pH, the diameter slightly increased.https://engagedscholarship.csuohio.edu/u_poster_2017/1045/thumbnail.jp

    ENGL 1301 - English Composition I - Language and Communication

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    This OER packet contains the course materials for ENGL 1301 - English Composition I . In academic settings, the reasons for writing fulfill four main purposes: to summarize, to analyze, to synthesize, and to evaluate. You will encounter these four purposes not only as you read for your classes but also as you read for work or pleasure. Because reading and writing work together, your writing skills will improve as you read. Eventually, your instructors will ask you to complete assignments specifically designed to meet one of the four purposes. As you will see, the purpose for writing will guide you through each part of the paper, helping you make decisions about content and style. For now, identifying these purposes by reading paragraphs will prepare you to write individual paragraphs and to build longer assignments.https://digitalcommons.pvamu.edu/pv-open-education-resources/1004/thumbnail.jp

    The Development and Evaluation of Experiential Learning Workshops for 4-H Volunteers

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    A series of three Experiential Learning (EL) workshops was designed by county- and campus-based researchers with the goal of improving the understanding and application of EL among volunteers in the University of California\u27s 4-H Youth Development Program. The workshop series was implemented and evaluated using surveys and focus group interviews. Outcome data showed improved participant understanding of EL, the learning cycle, inquiry-based methods, and curriculum development. Additionally, volunteers\u27 competence and confidence in delivering and developing experiential learning opportunities increased

    The Intrinsic Connectome of the Rat Amygdala

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    The connectomes of nervous systems or parts there of are becoming important subjects of study as the amount of connectivity data increases. Because most tract-tracing studies are performed on the rat, we conducted a comprehensive analysis of the amygdala connectome of this species resulting in a meta-study. The data were imported into the neuroVIISAS system, where regions of the connectome are organized in a controlled ontology and network analysis can be performed. A weighted digraph represents the bilateral intrinsic (connections of regions of the amygdala) and extrinsic (connections of regions of the amygdala to non-amygdaloid regions) connectome of the amygdala. Its structure as well as its local and global network parameters depend on the arrangement of neuronal entities in the ontology. The intrinsic amygdala connectome is a small-world and scale-free network. The anterior cortical nucleus (72 in- and out-going edges), the posterior nucleus (45), and the anterior basomedial nucleus (44) are the nuclear regions that posses most in- and outdegrees. The posterior nucleus turns out to be the most important nucleus of the intrinsic amygdala network since its Shapley rate is minimal. Within the intrinsic amygdala, regions were determined that are essential for network integrity. These regions are important for behavioral (processing of emotions and motivation) and functional (memory) performances of the amygdala as reported in other studies
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