bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transport Model for Microfluidic Device for Cell Culture and Tissue Development
Authors: Inamdar Niraj , Griffith Linda , Borenstein Jeffrey T. 
Published: September 2011

ABSTRACTIn recent years, microfluidic devices have emerged as a platform in which to culture tissue for various applications such as drug discovery, toxicity testing, and fundamental investigations of cell-cell interactions. We examine the transport phenomena associated with gradients of soluble factors and oxygen in a microfluidic device for co-culture. This work focuses on emulating conditions known to be important in sustaining a viable culture of cells. Critical parameters include the flow and the resulting shear stresses, the transport of various soluble factors throughout the flow media, and the mechanical arrangement of the cells in the device. Using analytical models derived from first principles, we investigate interactions between flow conditions and transport in a microfluidic device. A particular device of interest is a bilayer configuration in which critical solutes such as oxygen are delivered through the media into one channel, transported across a nanoporous membrane, and consumed by cells cultured in another. The ability to control the flow conditions in this membrane bilayer device to achieve sufficient oxygenation without shear damage is shown to be superior to the case present in a single channel system. Using the results of these analyses, a set of criteria that characterize the geometric and transport properties of a robust microfluidic device are provided.
Crystalline Alignment and In-plane Texture Improvement of Buffer Layers Deposited on NiW Tapes
Authors: Liu Linfei , Li Yijie , Liu Huaran , Song Xiaokun , Hong Dan , Wang Ying , Xu Da 
Published: September 2011

ABSTRACTIn order to deposit YBCO coated conductor with high critical current densities on rolling assisted biaxially textured Ni-W tapes, this paper has systematically studied the influence of deposition conditions on the orientation, in-plane texture and surface morphology of buffers and superconducting layers. It was found that the crystalline alignment and the in-plane texture of cerium oxide cap-layers were well improved by optimizing deposition parameters. The full width at half maximum of phi-scan x-ray diffraction peaks were reduced from original values of 7-8 degrees to 5-6 degrees. A high critical current density of 4.6×106 A/cm2 has been achieved on optimized buffer layers. This value is comparable with the critical current density of YBCO thin films deposited on single crystalline substrates.
Development of the Grain Size Distribution During the Crystallization of an Amorphous Solid
Authors: Bill Andreas , Bergmann Ralf B. 
Published: September 2011

ABSTRACTWe present an overview of the theory developed over the last few years to describe the crystallization of amorphous solids. The microstructure of the crystallizing solid is described in terms of the grain size distribution (GSD). We propose a partial differential equation that captures the physics of crystallization in random nucleation and growth processes. The analytic description is derived for isotropic and anisotropic growth rates and allows for the analysis of different stages of crystallization, from early to full crystallization. We show how the timedependence of effective nucleation and growth rates affect the final distribution. In particular, we demonstrate that for cases described by the Kolmogorov-Avrami-Mehl-Johnson (KAMJ) model applicable to a large class of crystallization processes a lognormal type distribution is obtained at full crystallization. The application of the theory to the crystallization of silicon thin films is discussed.
Computational Study of the Electronic Performance of Cross-Plane Superlattice Peltier Devices
Authors: Jeong Changwook , Klimeck Gerhard , Lundstrom Mark 
Published: September 2011

ABSTRACTWe use a state-of-the-art non-equilibrium quantum transport simulation code, NEMO-1D, to address the device physics and performance benchmarking of cross-plane superlattice Peltier coolers. Our findings show quantitatively how barriers in cross-plane superlattices degrade the electrical performance, i.e. power factor. The performance of an In0.53Ga0.47As/In0.52Al0.48As cross-plane SL Peltier cooler is lower than that of either a bulk In0.53Ga0.47As or bulk In0.52Al0.48As device, mainly due to quantum mechanical effects. We find that a cross-plane SL device has a Seebeck coefficient vs. conductance tradeoff that is no better than that of a bulk device. The effects of tunneling and phase coherence between multi barriers are examined. It is shown that tunneling, SL contacts, and coherency only produce oscillatory behavior of Seebeck coefficient vs. conductance without a significant gain in PF. The overall TE device performance is, therefore, a compromise between the enhanced Seebeck coefficient and degraded conductance.
Thermoelectric Properties of Carbon Nanotubes Added n-type CoSb3 Compound
Authors: Itoh Takashi , Tachikawa Masashi 
Published: September 2011

ABSTRACTCobalt triantimonide compounds are well known as materials with good thermoelectric properties over temperature range of 550-900 K. For further improving thermoelectric performance, reduction of thermal conductivity is required. In this study, we attempted to disperse carbon nanotubes (CNTs) homogeneously into the n-type CoSb3 compound for lowering lattice thermal conductivity by the phonon scattering. Powders of Co, Ni, Sb and Te were blended with molar ratios of n-type Co0.92Ni0.08Sb2.96Te0.04 compound, and the compound was synthesized through a pulse discharge sintering (PDS) process. After coarsely grinding the synthesized compound, CNTs were mixed with the compound powder at different mass% (0, 0.01, 0.05 and 0.1 mass%). Then, the mixture was mechanically ground with a planetary ball milling equipment. The ground composite powder was compacted and sintered by PDS. Thermoelectric properties (Seebeck coefficient, electrical resistivity and thermal conductivity) of the sintered samples were measured. It was confirmed that the fibrous CNTs existed homogeneously in the compound matrix. The absolute value of Seebeck coefficient slightly decreased with increase of CNT content. The minimum thermal conductivity was obtained at addition of 0.01mass%CNT, and the electrical resistivity was a little increased with CNT content. The maximum ZT of 0.98 was achieved at 853 K in the 0.01mass%CNT-added sample.
Novel Lead Telluride Based Thermoelectric Materials
Authors: Wu Chun-I , Girard Steven N. , Sootsman Joe , Timm Edward , Case Eldon D. , Kanatzidis Mercouri G. , Schock Harold , Chung Duck Young , Hogan Timothy P. 
Published: September 2011

ABSTRACTPbTe-PbS materials are promising for thermoelectric power generation applications. For the composition of (Pb0.95Sn0.05Te)0.92(PbS)0.08 nanostructuring from nucleation and growth and spinodal decomposition has been reported along with thermal conductivity of approximately 1.1 W/m·K at 650 K [1]. Based on temperature-dependent measurements of electrical conductivity, thermopower, and thermal conductivity, the thermoelectric figure of merit, ZT, are ~1.5 at 650 K for cast ingots.To develop larger quantities of material for device fabrication, advancement in the synthesis, processing and production of (Pb0.95Sn0.05Te)0.92(PbS)0.08 is necessary. Powder processing of samples is a well-known technique for increasing sample strength, and uniformity. In this presentation, we show sample fabrication and processing details of pulsed electric current sintering (PECS) processed (Pb0.95Sn0.05Te)0.92(PbS)0.08 materials and their thermoelectric properties along with the latest advancements in the preparation of these materials.
Polyethyleneimine Functionalized ZnO Quantum Dots and their Binding Interaction with Bovine Serum Albumin Protein
Authors: Joshi Prachi , Chakraborti Soumyananda , Chakrabarti Pinak , Singh Surinder P. , Ansari Z. A. , Shanker Virendra 
Published: September 2011

ABSTRACTWater stable fluorescent ZnO quantum dots (QDs) have been synthesized by wet chemical route in presence of hydrophilic capping agent polyethyleneimine (PEI) as stabilizing agent. The binding interaction of prepared ZnO QDs is studied with bovine serum albumin (BSA) protein. X-ray diffraction measurement reveals hexagonal wurtzite structure of as synthesized ZnO QDs with an average size 4-6 nm, determined using Scherer’s equation and confirmed by transmission electron microscopy (TEM). The ZnO/PEI QDs exhibit strong yellow-green emission centered at 555 nm (2.23 eV). The interaction between BSA and ZnO/PEI QDs has been studied by using spectroscopic and calorimetric methods. Static mode of tryptophan quenching in BSA by ZnO/PEI QDs indicates that a ground state complex formation is taking place between ZnO/PEI and BSA, where, the week interactions (hydrogen bonding and hydrophobic interaction) are contributing towards the stability of the complex.
Patterning Nanomaterials on Fragile Micromachined Structures using Electron Beam Lithography
Authors: Das Kaushik , Hubert Pascal , Vengallatore Srikar 
Published: September 2011

ABSTRACTIntegration of nanomaterials (in the form of quantum dots, nanotubes, nanowires, nanocrystalline thin films, and nanocomposite films) with micromachined structures and devices has the potential to enable the development of microelectromechanical systems (MEMS) with enhanced functionality and improved performance. Here, we present a fabrication approach that combines spray-coating of electron beam resist with direct-write electron beam lithography to pattern nanomaterials on fragile micromachined components. Polymers and metallic structures in the form of arrays of holes, concentric circles, and arrays of lines, with critical dimensions ranging from 135 nm to 500 nm, were patterned directly on various micromachined structures including commercial metal-coated silicon microcantilevers used for atomic force microscopy, and commercial plate-mode SiC/AlN microresonators used for sensing.
Decreased Attachment of Bacteria to Lubricin Coated Intraocular Lenses
Authors: Aninwene George E. , Taylor Erik , Mei Amy , Jay Gregory D. , Webster Thomas J. 
Published: September 2011

ABSTRACTLubricin is an amphiphilic glycoprotein that is found in the synovial fluid [1]. This protein holds promise as an anti-biofouling agent. This study investigated lubricin’s ability to prevent bacterial attachment and proliferation on intraocular lenses. The findings from this study indicated that lubricin is able to reduce the attachment of Staphylococcus aureus to poly (methyl methacrylate) intraocular lens. Lubricin coatings were confirmed on the surfaces after a 2 hour soak by changes in surface energy. Also, lubricin reduced bacterial proliferation.
Study Abroad Experiences in the Developing World: Opportunities and Challenges
Authors: LeSar Richard A. , Bryden Kenneth M. 
Published: September 2011

ABSTRACTOver the past three years the Departments of Materials Science and Engineering and Mechanical Engineering at Iowa State University have conducted a study-abroad course for ISU undergraduates in a small, isolated, village in the country of Mali, in western, sub-Saharan Africa. Most, if not all, of the people in the village live under conditions that the World Bank refers to as extreme poverty. The focus of the course is on the development of sustainable technologies that are appropriate for the people in this village and villages similar to it. Our goal is to offer students a chance to develop such technologies, in the end changing how they view engineering and their role as engineers. One of the challenges of the course is how to integrate this high value off-campus experience into the on-campus curriculum. To do this we have linked two on-campus sustainable engineering courses (sustainable engineering systems and appropriate technology design) with this study abroad course. In this paper, we discuss the course in more detail, with a focus on an assessment of how well we are meeting our objectives. We shall also discuss the challenges of holding such a course and will offer some advice for those who may wish to venture along the same path.
Mechanism of hole inlet closure in shape transformation of hole arrays on Si(001) substrates by hydrogen annealing
Authors: Hiruta Reiko , Kuribayashi Hitoshi , Sudoh Koichi , Shimizu Ryosuke 
Published: September 2011

ABSTRACTWe investigated the process of the hole inlet closure in surface-diffusion-driven transformation of arrays of high-aspect-ratio holes on Si(001) substrates. The inlet gradually shrinks while keeping the circular shape because of lateral bulging of the inlet surface. We observed complicated top view morphologies reflecting the four-fold symmetry of the Si(001) surface on the inlet surface. Large {111} and {113} facets are formed in the four equivalent azimuths of the [110], while corrugated patterns arise in the four equivalent azimuths of the [100]. Atomic force microscopy observations reveal that the corrugated pattern is composed of three types of small facets, namely, {110} and two {113} in relation of the mirror symmetry. The corrugated pattern formation is due to the geometrical restriction that there is no stable facet between (001) and (010) in the [010] azimuth. The observed morphological evolution is interpreted as surface-diffusion-driven transformation under constraint of the anisotropic surface energy of Si.
SU8 / modified MWNT composite for piezoresistive sensor application
Authors: Ray Prasenjit , Seena V. , Khare Rupesh A. , Bhattacharyya Arup R. , Apte Prakash R. , Rao Ramgopal 
Published: September 2011

ABSTRACTSU-8 is being increasingly used as a compliant structural material for MEMS applications due to its interesting properties such as lower Young’s modulus and higher mechanical and thermal stability. One of the popular classes of MEMS devices is a piezoresitive microcantilever. Ultra-sensitive polymer composite cantilevers made up of SU-8 as a structural layer and 10% carbon Black in SU8 as a piezoresistive layer with lower Young’s modulus and higher gauge factor have been reported recently by our group. Higher electrical conductivity at lower concentration of conductive filler is of increased interest. Here we report a novel composite with purified multiwall carbon nanotubes (MWNT) in SU8 as a piezoresistor. MWNT were modified with octadecyl triphenyl phosphonium bromide (OTPB) in order to achieve debundled MWNT. A microcantilever device with integrated MWNT/SU-8 composite has been fabricated and characterized.
Team-based Interdisciplinary Materials Research using Image Processing
Authors: Garofano Jacquelynn , Sadowski Thomas , DaPonte John , Broadbridge Christine 
Published: September 2011

ABSTRACTThere is an acute and well-documented need for image processing of microscopy data in materials science regarding, for example, the characterization of the structure/property relationship of a given materials system. In our work, image processing has been used as a framework for conducting interdisciplinary team-based research that effectively integrates programs within the Center for Research on Interface Structures and Phenomena (CRISP) Materials Research Science and Engineering Center (MRSEC), e.g. research experiences for undergraduates (REU), teachers (RET) and high school fellowships. This research resulted from a five-year long collaboration between CRISP and the Physics and Computer Science Departments at Southern Connecticut State University (SCSU). This paper will focus on the implementation of team-based research experiences as a vehicle for interdisciplinary science and education. Representative results of several of the studies are presented and discussed.
Growth and characterization of transition-metal and rare-earth doped III-nitride semiconductors for spintronics
Authors: Asahi H. , Hasegawa S. , Zhou Y.K. , Emura S. 
Published: September 2011

ABSTRACTTransition metal (Cr) and rare-earth (Dd, Dy) doped III-nitride semiconductor bulk layers and superlattice (SL) structures are grown on sapphire (0001) substrates and GaN (0001) templates by plasma-assisted molecular-beam epitaxy. For the GaGdN/GaN and InGaGdN/GaN SL and Si co-doped samples, enhancement of magnetization and magnetic moment are observed, suggesting the carrier-mediated ferromagnetism. Low temperature growth of GaGdN can increase the Gd concentration and magnetization. Results for the Dy-doped GaN as well as the GaCrN/AlN/GaCrN tunnel magneto-resistance (TMR) diodes are also described.
Conductive Nano-brush Synthesized by Physical Grafting of Conducting Polymers on Carbon Nanotube
Authors: Purohit Kaushalkumar , Mirville Maureen , Yang Sze C. , Shukla Arun , Chalivendra Vijaya B. 
Published: September 2011

ABSTRACTWe report a novel method for synthesizing electrically conductive nano-brush (CNB) by physical grafting of organic conducting polymers on carbon nano tubes (CNT). The objective for this synthesis is to produce nano tubes having a CNT stem coated with flexible electronic conducting polymers. The nano-brush is to be blended into common polymers (e.g. epoxy, polyurethane, and poly(vinyl alcohol)) to form electrically conductive composite material. The flexible organic conducting polymer in CNB is a potentially sensitive electronic probe for mechanically induced nano-deformation of the composite because it is molecularly entangled with the host polymers. The electrical networks of CNB embedded in polymeric composites are potentially useful as in situ sensors for monitoring material deformation with an unprecedented level of sensitivity. The composite material is “smart” in the sense that it self-reports the structural “health” before load induced material failure.Our method for grafting conducting polymer does not require chemical reactions with the surface atoms of the carbon nano tube. We used physical adsorption to graft electronic conducting polymer to CNT. We first synthesized a water-soluble electronic conducting polymer which is a molecular complex between poly(acrylic acid) and polyaniline. The CNT solid were dispersed and un-bundled by sonnication in the conducting polymer solution. Due to the high affinity between CNT and the conducting polymer, the surface of CNT can be fully covered with the conducting polymer. The experimental data is consistent with a structure of nano brush with high density of conducting polymers grafted on the CNT surface.
Monte Carlo Simulations of the Exchange Bias Effect in Heusler Ni50Mn37.5Sb12.5 Alloys Using Real Unit Cell
Authors: Buchelnikov Vasiliy D. , Taranenko Ivan A. , Sokolovskiy Vladimir V. , Taskaev Sergey V. , Zagrebin Mikhail A. , Entel Peter 
Published: September 2011

ABSTRACTIn present work we propose a theoretical model for investigation of the exchange bias effect in Ni50Mn37.5Sb12.5 alloy. In the model, we use a three-dimensional cubic lattice with periodic boundary conditions. Also we take into account the magnetic interactions between atoms in 1st, 2nd and 3rd coordination spheres and the ferromagnetic and antiferromagnetic anisotropy terms. It is shown that the obtained theoretical temperature dependence of the exchange bias field for Ni50Mn37.5Sb12.5 alloy is close to the experimental data.
Layered and Functionally Graded Nanocomposite Thin Films with Unique Mechanical Properties
Authors: Farias Stephen L. , Breysse Patrick C. , Chien Chai-Ling , Cammarata Robert C. 
Published: September 2011

AbstractA novel electrochemical deposition method for manufacturing functionally graded, oxide-dispersion strengthened metal matrix nanocomposites will be presented. Using a rotating disk electrode and depositing from an electrolyte containing a suspension of oxide nanoparticles, metal-ceramic nanocomposites have been produced. This method leads to precise control over the volume fraction of the oxide in the nanocomposite and allows for the manufacturing of compositionally uniform, periodically layered, or functionally graded structures. In the higher order structures the composition variation can be finely tuned with nanometer resolution, and the characteristic microstructural length scale (e.g., individual layer thickness) can range from microns up to millimeters. Using indentation methods, the nanocomposites are shown to display enhanced and tunable mechanical properties.
Phase diagrams of Ni2+xMn1-xGa Heusler alloys from Hubbard Hamiltonian with account of Jahn-Teller effect
Authors: Zagrebin Mikhail A. , Buchelnikov Vasiliy D. , Taskaev Sergey V. , Fedulova Natal’ya Yu. 
Published: September 2011

ABSTRACTIn this work a microscopic Hamiltonian is investigated using the Hubbard model for a ferromagnet with two degenerate bands, taking into account the Jahn-Teller effect. A macroscopic free energy is obtained from the microscopic Hubbard Hamiltonian. All free energy coefficients depend on microscopic parameters: temperature T and composition x. As a result of analytical minimization of free energy, phase diagrams are numerically constructed. It is shown that at certain values of parameters on the phase diagrams there are thermodynamic paths which correspond to experimentally observed sequences of phase transitions. Using density of states spectra for different compositions x the T-x phase diagram is numerically constructed. This phase diagram can theoretically explain experimentally observed behavior of the temperatures of phase transitions.
Engineering Elephants: Introducing Young Children to Engineering
Authors: Hunt Emily M. , Pantoya Michelle L. , Reeves Abbye M. 
Published: September 2011

ABSTRACTIn this study, the authors focused on children from 2-8 years of age and asked the simple question: what do engineers do? The number one response was: “I don’t know”, the number two response was “they drive a train.” While children are very familiar with professionals such as doctors, teachers, nurses, firefighters and policemen, they are rarely introduced to engineers. With this motivation, the authors developed a novel children’s book on engineering: Engineering Elephants. This book is an outreach tool that introduces children to the dynamic world of engineering design through roller coasters, fireworks, and a plethora of other exciting adventures. The book teaches children about relevant topics such as nanotechnology, renewable energy, and prosthetics by engaging them through an interactive journey of an elephant and his questioning of the world around him. The text was strategically developed using the language of science (asking questions) and introducing vocabulary relevant to science and math using a lyrical pattern. This presentation will highlight the development of this book as an instructional aid but also detail the response of various age groups to engineering activities presented as a companion to this book. In particular, an elementary school district in West Texas designed a 4-5th grade 3-week summer school curriculum around this book. Results from this study will have an impact on future generations by inspiring them to consider the exciting profession of engineering at an early age.
CVD Growth of Graphene on Three Types of Epitaxial Metal Films on Sapphire Substrate
Authors: Nozawa Katsuya , Matsukawa Nozomu , Toyoda Kenji , Yoshii Shigeo 
Published: September 2011

ABSTRACTGraphene growth by chemical vapor deposition (CVD) was studied on three types of epitaxial metal films with different crystal structures on sapphire. Nickel (face-centered-cubic: fcc), Ru (hexagonal-closed-pack: hcp), and Co (fcc at temperature for graphene growth and hcp at R.T.) were deposited on c-face sapphire substrates and annealed in a furnace for solid phase epitaxial growth. Graphene layers were grown by CVD with methane gas on the epitaxial metal film. The graphene layer uniformity was consistent with the structural simplicity of the metal film. The Ru sample had a single domain in the metal film and the highest graphene uniformity. The Co sample had a very complex crystal structure in the metal film and the poorest uniformity in graphene. The Ni sample had two types of stacking domains in the metal film and the graphene layer was uniform on each domain, but inhomogeneity was observed at domain boundaries.