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Materials Science and Engineering

Portland State University

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Full-Text Articles in Engineering

An In Situ Experimental Study Of Grain Growth In A Nanocrystalline Fe91ni8zr1 Alloy, Hasan Kotan, Kris A. Darling, Mostafa Saber, Ronald O. Scattergood, Carl C. Koch Mar 2013

An In Situ Experimental Study Of Grain Growth In A Nanocrystalline Fe91ni8zr1 Alloy, Hasan Kotan, Kris A. Darling, Mostafa Saber, Ronald O. Scattergood, Carl C. Koch

Mechanical and Materials Engineering Faculty Publications and Presentations

Grain growth and microstructural evolution of thermally stabilized Fe91Ni8Zr1 were investigated by in situ and ex situ studies. Our investigations suggest that the microstructural evolution is fairly slow and the microstructure shows stabilization up to about 700 °C. Above this temperature, a certain fraction of grains grow abnormally into the nanocrystalline matrix, resulting in a bimodal microstructure and causing the complete loss of thermal stability. The reason for abnormal grain growth and the loss of thermal stability is identified as the appearance of the fcc γ-phase and consequent reduction in the total area of grain boundaries and the overall stored …


A Mean Curvature Model For Capillary Flows In Asymmetric Containers And Conduits, Yongkang Chen, Noël Tavan, Mark M. Weislogel Aug 2012

A Mean Curvature Model For Capillary Flows In Asymmetric Containers And Conduits, Yongkang Chen, Noël Tavan, Mark M. Weislogel

Mechanical and Materials Engineering Faculty Publications and Presentations

Capillarity-driven flows resulting from critical geometric wetting criterion are observed to yield significant shifts of the bulk fluid from one side of the container to the other during "zero gravity" experiments. For wetting fluids, such bulk shift flows consist of advancing and receding menisci sometimes separated by secondary capillary flows such as rivulet-like flows along gaps. Here we study the mean curvature of an advancing meniscus in hopes of approximating a critical boundary condition for fluid dynamics solutions. It is found that the bulk shift flows behave as if the bulk menisci are either “connected” or "disconnected." For the connected …


Plasma Levels Of Polychlorinated Biphenyls, Non-Hodgkin Lymphoma, And Causation, Michael D. Freeman, Sean S. Kohles Jan 2012

Plasma Levels Of Polychlorinated Biphenyls, Non-Hodgkin Lymphoma, And Causation, Michael D. Freeman, Sean S. Kohles

Mechanical and Materials Engineering Faculty Publications and Presentations

Polychlorinated biphenyls (PCBs) are synthetic chlorinated hydrocarbons that have extensively polluted the environment and bioaccumulated in the food chain. PCBs have been deemed to be probable carcinogens by the Environmental Protection Agency, and exposure to high levels of PCBs has been consistently linked to increased risk of non-Hodgkin lymphoma (NHL). In the present article we present a forensic epidemiologic evaluation of the causal relationship between NHL and elevated PCB levels via application of the Bradford-Hill criteria. Included in the evaluation is a meta-analysis of the results of previously published case-control studies in order to assess the strength of association between …


Ultrasonic Wave Propagation Assessment Of Native Cartilage Explants And Hydrogel Scaffolds For Tissue Engineering, Sean S. Kohles, Shelley S. Mason, Anya P. Adams, Robert J. Berg, Jessica Blank, Fay Gibson, Johnathan Righetti, Lesha S. Washington, Asit K. Saha Jan 2012

Ultrasonic Wave Propagation Assessment Of Native Cartilage Explants And Hydrogel Scaffolds For Tissue Engineering, Sean S. Kohles, Shelley S. Mason, Anya P. Adams, Robert J. Berg, Jessica Blank, Fay Gibson, Johnathan Righetti, Lesha S. Washington, Asit K. Saha

Mechanical and Materials Engineering Faculty Publications and Presentations

Non-destructive techniques characterising the mechanical properties of cells, tissues, and biomaterials provide baseline metrics for tissue engineering design. Ultrasonic wave propagation and attenuation has previously demonstrated the dynamics of extracellular matrix synthesis in chondrocyte-seeded hydrogel constructs. In this paper, we describe an ultrasonic method to analyse two of the construct elements used to engineer articular cartilage in real-time, native cartilage explants and an agarose biomaterial. Results indicated a similarity in wave propagation velocity ranges for both longitudinal (1500-1745 m/s) and transverse (350-950 m/s) waveforms. Future work will apply an acoustoelastic analysis to distinguish between the fluid and solid properties including …


Research On Coupled Human And Natural Systems (Chans): Approach, Challenges, And Strategies, Marina Alberti, Heidi Asbjornsen, Lawrence A. Baker, Nicholas Brozović, Laurie E. Drinkwater, Scott A. Drzyzga, Claire A. Jantz, José Fragoso, Daniel S. Holland, Timothy A. Kohler, Jianguo Liu, William J. Mcconnell, Herbert D. G. Maschner, James D. A. Millington, Michael Monticino, Guillermo Podestá, Robert Gilmore Pontius Jr., Charles L. Redman, Nicholas J. Reo, David J. Sailor, Gerald Urquhart Apr 2011

Research On Coupled Human And Natural Systems (Chans): Approach, Challenges, And Strategies, Marina Alberti, Heidi Asbjornsen, Lawrence A. Baker, Nicholas Brozović, Laurie E. Drinkwater, Scott A. Drzyzga, Claire A. Jantz, José Fragoso, Daniel S. Holland, Timothy A. Kohler, Jianguo Liu, William J. Mcconnell, Herbert D. G. Maschner, James D. A. Millington, Michael Monticino, Guillermo Podestá, Robert Gilmore Pontius Jr., Charles L. Redman, Nicholas J. Reo, David J. Sailor, Gerald Urquhart

Mechanical and Materials Engineering Faculty Publications and Presentations

Understanding the complexity of human–nature interactions is central to the quest for both human well-being and global sustainability. To build an understanding of these interactions, scientists, planners, resource managers, policy makers, and communities increasingly are collaborating across wide-ranging disciplines and knowledge domains. Scientists and others are generating new integrated knowledge on top of their requisite specialized knowledge to understand complex systems in order to solve pressing environmental and social problems (e.g., Carpenter et al. 2009). One approach to this sort of integration, bringing together detailed knowledge of various disciplines (e.g., social, economic, biological, and geophysical), has become known as the …


Manipulation Of Suspended Single Cells By Microfluidics And Optical Tweezers, Nathalie Neve De Mevergnies, Sean S. Kohles, Shelley R. Winn, Derek C. Tretheway Sep 2010

Manipulation Of Suspended Single Cells By Microfluidics And Optical Tweezers, Nathalie Neve De Mevergnies, Sean S. Kohles, Shelley R. Winn, Derek C. Tretheway

Mechanical and Materials Engineering Faculty Publications and Presentations

Chondrocytes and osteoblasts experience multiple stresses in vivo. The optimum mechanical conditions for cell health are not fully understood. This paper describes the optical and microfluidic mechanical manipulation of single suspended cells enabled by the μPIVOT, an integrated micron resolution particle image velocimeter (μPIV) and dual optical tweezers instrument (OT). In this study, we examine the viability and trap stiffness of cartilage cells, identify the maximum fluid-induced stresses possible in uniform and extensional flows, and compare the deformation characteristics of bone and muscle cells. These results indicate cell photodamage of chondrocytes is negligible for at least 20 min for laser …


Technical Research Needs For Sustainable Buildings: Results From A Multidisciplinary Nsf Workshop, Leidy Klotz, Vivien Loftness, Gregor Henze, David J. Sailor, David Riley Oct 2009

Technical Research Needs For Sustainable Buildings: Results From A Multidisciplinary Nsf Workshop, Leidy Klotz, Vivien Loftness, Gregor Henze, David J. Sailor, David Riley

Mechanical and Materials Engineering Faculty Publications and Presentations

This article describes research needs for sustainable buildings as defined in a July 2009 National Science Foundation-sponsored workshop. This workshop brought together building researchers with researchers in the areas of distributed renewable energy and multifunctional materials to engage their expertise and identify overlapping research needs and opportunities. An overview of sustainable building design provided the broad context for discussion. This overview was followed by focused presentations in building control systems, advanced building envelopes, and systems and process integration. In addition, presentations on distributed renewable energy and multi-functional materials supported the participants in outlining and generating research needs that connect the …


Metamaterial Devices For The Terahertz Band, Gabriel Paul Kniffin Jun 2009

Metamaterial Devices For The Terahertz Band, Gabriel Paul Kniffin

Center for Electron Microscopy and Nanofabrication Publications and Presentations

Terahertz (THz) and metamaterials are both hot topics in electromagnetics research. The THz band (0.1-10 THz) lies in the ‘gap’ between microwave and far infrared regions. Research is currently underway to characterize how these waves interact with matter, with potential applications including security screening, medical imaging, and non-destructive evaluation. Metamaterials are artificial materials containing sub-wavelength structures whose material properties, μ and ǫ can be ‘tuned’ to desired specifications, including simultaneously negative values, resulting in exotic properties such as a negative refractive index. Current metamaterials research includes the design of devices that operate at THz frequencies, filling a niche left wide …


Gravity Effects On Capillary Flows In Sharp Corners, Enrique Ramé, Mark M. Weislogel Apr 2009

Gravity Effects On Capillary Flows In Sharp Corners, Enrique Ramé, Mark M. Weislogel

Mechanical and Materials Engineering Faculty Publications and Presentations

We analyze the effect of gravity on capillary flows in sharp corners. We consider gravity perpendicular and parallel to the channel axis. We analyze both steady and unsteady flows. In the steady analysis the main result is a closed form expression for the flow rate as a function of the two gravity components. Good agreement with steady experiments is offered as support of the model. The unsteady analysis is restricted to “small” values of the two gravity parameters and is accomplished using a similarity formulation. The similarity coefficients of the gravity corrections are fully determined by the coefficients of the …


Crystallography Open Database – An Open-Access Collection Of Crystal Structures, Saulius Grazulis, Daniel Chateigner, Robert T. Downs, A. F. T. Yokochi, Miguel Quirós, Luca Lutterotti, Elena Manakova, Justas Butkus, Peter Moeck, Armel Le Bail Jan 2009

Crystallography Open Database – An Open-Access Collection Of Crystal Structures, Saulius Grazulis, Daniel Chateigner, Robert T. Downs, A. F. T. Yokochi, Miguel Quirós, Luca Lutterotti, Elena Manakova, Justas Butkus, Peter Moeck, Armel Le Bail

Physics Faculty Publications and Presentations

The Crystallography Open Database (COD), which is a project that aims to gather all available inorganic, metal–organic and small organic molecule structural data in one database, is described. The database adopts an openaccess model. The COD currently contains 80,000 entries in crystallographic information file format, with nearly full coverage of the International Union of Crystallography publications, and is growing in size and quality.


A Better Nondimensionalization Scheme For Slender Laminar Flows: The Laplacian Operator Scaling Method, Mark M. Weislogel, Yongkang Chen, D. Bolleddula Sep 2008

A Better Nondimensionalization Scheme For Slender Laminar Flows: The Laplacian Operator Scaling Method, Mark M. Weislogel, Yongkang Chen, D. Bolleddula

Mechanical and Materials Engineering Faculty Publications and Presentations

A scaling of the two-dimensional Laplacian operator is demonstrated for certain solutions (at least) to Poisson’s equation. It succeeds by treating the operator as a single geometric scale entity. The belated and rather subtle method provides an efficient assessment of the geometrical dependence of the problem and is preferred when practicable to the hydraulic diameter or term-by-term scaling for slender fully developed laminar flows. The improved accuracy further reduces the reliance of problems on widely varying numerical data or cumbersome theoretical forms and improves the prospects of exact or approximate theoretical analysis. Simple example problems are briefly described that demonstrate …


Nano Quasicrystal Formation And Local Atomic Structure In Zr––Pd And Zr––Pt Binary Metallic Glasses, Junji Saida, Takashi Sanada, Shigeo Sato, Muneyuki Imafuku, Chunfei Li, Akihisa Inoue Jan 2008

Nano Quasicrystal Formation And Local Atomic Structure In Zr––Pd And Zr––Pt Binary Metallic Glasses, Junji Saida, Takashi Sanada, Shigeo Sato, Muneyuki Imafuku, Chunfei Li, Akihisa Inoue

Center for Electron Microscopy and Nanofabrication Publications and Presentations

Formation of the nanoscale icosahedral quasicrystalline phase (I-phase) in the melt-spun Zr70Pd30 and Zr80Pt20 binary metallic glasses were reported. Local atomic structure in the glassy and quasicrystal (QC)-formed states were also analyzed by XRD and EXAFS measurements in order to investigate the formation mechanism of QC phase. The distorted icosahedral-like local structure can be identified around Zr atom in the Zr70Pd30 metallic glass. In the QC formation process, a change of local environment around Zr is detected, in which the approximately one Zr atom substitutes for one Pd atom. In contrast, …


The Urban Heat Island Mitigation Impact Screening Tool (Mist), David J. Sailor, Nikolaas Dietsch Oct 2007

The Urban Heat Island Mitigation Impact Screening Tool (Mist), David J. Sailor, Nikolaas Dietsch

Mechanical and Materials Engineering Faculty Publications and Presentations

A web-based software tool has been developed to assist urban planners and air quality management officials in assessing the potential of urban heat island mitigation strategies to affect the urban climate, air quality, and energy consumption within their cities. The user of the tool can select from over 170 US cities for which to conduct the analysis, and can specify city-wide changes in surface reflectivity and/or vegetative cover. The Mitigation Impact Screening Tool (MIST) then extrapolates results from a suite of simulations for 20 cities to estimate air temperature changes associated with the specified changes in surface characteristics for the …


Capillary-Driven Flows Along Rounded Interior Corners, Yongkang Chen, Mark M. Weislogel, Cory L. Nardin Nov 2006

Capillary-Driven Flows Along Rounded Interior Corners, Yongkang Chen, Mark M. Weislogel, Cory L. Nardin

Mechanical and Materials Engineering Faculty Publications and Presentations

The problem of low-gravity isothermal capillary flow along interior corners that are rounded is revisited analytically in this work. By careful selection of geometric length scales and through the introduction of a new geometric scaling parameter Tc, the Navier–Stokes equation is reduced to a convenient∼O(1) form for both analytic and numeric solutions for all values of corner half-angle α and corner roundedness ratio λ for perfectly wetting fluids. The scaling and analysis of the problem captures much of the intricate geometric dependence of the viscous resistance and significantly reduces the reliance on numerical data compared with several previous solution methods …


Dynamic Matrix Composition In Engineered Cartilage With Stochastic Supplementation Of Growth Factors, Asit K. Saha, J. (Jagannath) Mazumdar, Sean S. Kohles Jun 2005

Dynamic Matrix Composition In Engineered Cartilage With Stochastic Supplementation Of Growth Factors, Asit K. Saha, J. (Jagannath) Mazumdar, Sean S. Kohles

Mechanical and Materials Engineering Faculty Publications and Presentations

Dynamic extracellular matrix (ECM) synthesis is explored in a hypothesized engineered cartilage construct. Growth (α) and decay (β) rate parameters are developed from a previous engineered cartilage model. The presented mathematical model was constructed from the parameterized experimental data using a deterministic and stochastic examination of ECM synthesis based on a negative feedback control mechanism. A growth factor supplementation is incorporated in a probabilistic mathematical approach. The growth factor component modified an initial deterministic model through a Gaussian white noise fluctuation. As the primary constituents of ECM, the mathematical tool is intended to characterize the probable steady state distribution of …


Capillary Flow In Interior Corners: The Infinite Column, Mark M. Weislogel Nov 2001

Capillary Flow In Interior Corners: The Infinite Column, Mark M. Weislogel

Mechanical and Materials Engineering Faculty Publications and Presentations

Capillary flow of a sinusoidally perturbed liquid column in an interior corner of infinite extent is solved using lubrication theory. Due primarily to the length scales selected to nondimensionalize the momentum equation, an analytic time scale governing the settling of the perturbation is determined. The time scale, which is shown to be independent of a steady base state flow, proves useful in rapidly predicting transients for surface settling in certain liquid-bearing tanks of spacecraft employing interior corners for fluids management purposes. The asymptotic analysis is extended to address flows along interior corners whose faces are slightly nonplanar. The generalized formulation …


Application Of Tree-Structured Regression For Regional Precipitation Prediction Using General Circulation Model Output, Xiangshang Li, David J. Sailor Nov 2000

Application Of Tree-Structured Regression For Regional Precipitation Prediction Using General Circulation Model Output, Xiangshang Li, David J. Sailor

Mechanical and Materials Engineering Faculty Publications and Presentations

This study presents a tree-structured regression (TSR) method to relate daily precipitation with a variety of free-atmosphere variables. Historical data were used to identify distinct weather patterns associated with differing types of precipitation events. Models were developed using 67% of the data for training and the remaining data for model validation. Seasonal models were built for each of 2 US sites: San Francisco, California, and San Antonio, Texas. The average correlation between observed and simulated daily precipitation data series is 0.75 for the training set and 0.68 for the validation set. Relative humidity was found to be the dominant variable …


Capillary Surfaces In An Exotic Container: Results From Space Experiments, Paul Concus, Robert Finn, Mark M. Weislogel Sep 1999

Capillary Surfaces In An Exotic Container: Results From Space Experiments, Paul Concus, Robert Finn, Mark M. Weislogel

Mechanical and Materials Engineering Faculty Publications and Presentations

Experimental results from the Interface Configuration Experiment (ICE) performed aboard the Space Shuttle and the Mir Space Station are reported. The experiment concerns fluid interfaces in certain ‘exotic’ containers in a low-gravity environment. These containers are rotationally symmetric and have the property that for given contact angle and liquid volume, a continuum of distinct rotationally symmetric equilibrium configurations can appear, all of which have the same mechanical energy. These symmetric equilibrium configurations are unstable, in that deformations that are not rotationally symmetric can be shown mathematically to yield configurations with lower energy. It is found experimentally, in confirmation of mathematical …


Neutron-Scattering Study Of Librations And Intramolecular Phonons In Rb_{2.6}K_{0.4}C_{60}, D. Reznik, W. A. Kamitakahara, D. A. Neumann, J. R. D. Copley, J. E. Fischer, Robert M. Strongin, M. A. Cichy, Amos B. Smith Iii Jan 1994

Neutron-Scattering Study Of Librations And Intramolecular Phonons In Rb_{2.6}K_{0.4}C_{60}, D. Reznik, W. A. Kamitakahara, D. A. Neumann, J. R. D. Copley, J. E. Fischer, Robert M. Strongin, M. A. Cichy, Amos B. Smith Iii

Chemistry Faculty Publications and Presentations

We report the results of inelastic neutron-scattering measurements on Rb2.6K0.4C60. Librational modes were observed as broad peaks with maxima between 4.1 and 4.7 meV, as the temperature is lowered from 300 to 12 K. As in K3C60, no change in the width or position of the librational peak was observed when the sample was cooled through the superconducting transition. Thus any coupling of the librations to electronic states is small. The magnitude of the orientational potential barrier was estimated from the librational peak frequency. A flat background observed in the …