bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microfluidics and Beyond – Devices for Applications in Biotechnology -
Authors: Daub Martina , Kaack Rolf M. , Gutmann Oliver , Steinert Chris P. , Niekrawietz Remigius , Koltay Peter , Heij Bas de , Zengerle Roland 
Published: April 2011

AbstractFor the performance of certain analytical and diagnostic tasks in modern Life Science applications high throughput screening (HTS) methods are essential. Miniaturization, parallelization and automation allow to decrease consumption of expensive materials and lead to faster analyzing times. The miniaturization of total assay volumes by the use of microtiter plates as well as the microarray technology have revolutionized the field of biotechnology and Life Sciences. Neither printing of microarrays with droplet volumes of several picoliters, nor handling of precious enzymes in the upper nanoliter range can be accomplished with traditional liquid handling devices like air displacement pipettes. The development of novel low volume liquid handling devices, which are subject to current research, addresses the diverse requirements shifting steadily to lower volumes. Various novel non-contact dispensing methods in the nanoliter and picoliter range are presented and classified according to their working principles like air displacement and direct displacement methods (TopSpot®, NanoJetTM, Dispensing Well PlateTM). Properties of the various methods are compared in terms of flexibility, integration density, speed of operation, precision, addressable volume range and amenability to multi-parallel operation.
Three-Dimensional Representation of Curved Nanostructures
Authors: Huang Z. , Dikin D.A. , Ding W. , Qiao Y. , Fridman Y. , Ruoff R.S. 
Published: April 2011

AbstractNanostructures, such as nanowires, nanotubes, and nanocoils, can be described in many cases as quasi one-dimensional (1D) curved objects projecting in three-dimensional (3D) space. A parallax method to reconstruct the correct three-dimensional geometry of such 1D nanostructures is presented. A series of images were acquired at different view angles, and from those image pairs, 3D representations were constructed using a MATLAB program. Error analysis as a function of view-angle between the two images is discussed. As an example application, we demonstrate the importance of knowing the true 3D shape of Boron nanowires. Without precise knowledge of the nanowire's dimensions, diameter and length, mechanical resonance data cannot be properly fit to obtain an accurate estimate of the Young's modulus.
Determination of Ion Irradiation Influence on π-plasmon Properties of Carbon Nanotubes
Authors: Brzhezinskaya Mariya M. , Baitinger Eugen M. , Shnitov Vladimir V. , Smirnov Aleksey 
Published: April 2011

AbstractIn this paper, the results of experiments on irradiation of the singlewall (SWNT) and multiwall carbon nanotube (MWNT) samples by argon ions are presented. They were obtained by reflection electron energy loss spectroscopy and Auger electron spectroscopy.Results indicate the π-plasmon energy Eπ and the full width at half maximum (FWHM) of the plasma peak were sensitive to the dose of ion irradiation. In particular, the π-plasmon energy Eπ decreases and the plasma peak broadens with the increase of the dose of Ar+irradiation.The π-plasmon peak broadening is associated with damage of carbon nanotubes under ion irradiation. Possible causes of the carbon nanotubes deformation and influence of deformation on π-band structure of carbon nanotubes are discussed.
Fabrication and Characteristics of Zirconia-Alumina Composites with Bilayer Structure
Authors: Je Sung-Jae , Lee Myung-Won , Lee Jae-Ean , Jung Yeon-Gil , Park Dong-Soo , Paik Ungyu 
Published: April 2011

AbstractBilayer structures consisting of ZrO2-3mol% Y2O3(TZ-3Y) and zirconia-alumina composites as inner (substrate) and outer (coating) layers, respectively, are fabricated using gel-casting for the inner layer and dip-coating for the outer layer in aqueous system. The relatively tough TZ-3Y is used as the inner layer for damage absorption due to its mechanical properties. The mixture ratio of alumina/zirconia slips for dip-coating is 1:9, 2:8, and 3:7 as mole ratio. The processing additives for gel casting, such as dispersant, monomer, dimer, and initiator, are adjusted and optimized by measuring viscosity. From which the solid loading of starting material (TZ-3Y) is determined. The optimum amount of dispersant (D-3019; anionic dispersant agent) for TZ-3Y is 0.7 wt%. The slip pH affects the electric double layer in sols, which causes the different rheological behaviors and solid loadings. The castable solid loading of TZ-3Y is 37 vol%, showing a pseudoplastic rheological behavior. The effect of slip type (different mixture ratio) on sintered body is investigated through hardness (Vickers indentation), microstructure (SEM), and strength (4-point bending tests). Strength of sintered bodies after dip-coating into the slips is higher than that before dip-coating, but hardness is not much different among cases. The effects of thickness in the outer layer on damage resistance and mechanical properties of the bilayer structures are discussed extensively.
Instability Induced by Near-substrate Electric Field
Authors: Salac David , Lu Wei 
Published: April 2011

AbstractThis paper reports experimental work using an electric field close to a substrate to induce morphological patterns in a thin polymer film. The film was spin-coated onto a glass wafer, and subsequently heated to above its glass transition temperature to allow viscous flow. An electric field was applied by two parallel electrodes spacing 10 mm apart. The initially flat polymer/air interface lost stability and formed islands. The self-assembled islands exhibited a narrow size distribution and demonstrated spatial ordering. We attribute the pattern formation to the minimization of combined interface energy and electrostatic energy.
Nanocrystalline fcc metals: bridging experiments with simulations
Authors: Swygenhoven H. Van , Derlet P. M. , Frøseth A. G. , Petegem S. Van , Budrovic Z. , Hasnaoui A. 
Published: April 2011

AbstractAtomistic simulations have provided unprecedented insight into the structural and mechanical properties of nanocrystalline materials, highlighting the role of the non-equilibrium grain boundary structure in both inter- and intra-grains deformation processes. One of the most important results is the capability of the nanosized grain boundary to act as a source and sink for dislocations. However the extrapolation of this knowledge to the experimental regime requires a clear understanding of the temporal and spatial scales of the modelling technique and a detailed structural characterisation of the simulated samples. In this contribution some of the synergies that can be developed between atomistic simulations and experiments for this research field are briefly discussed by means of some typical examples.
Slip Transfer across Hetero-Interfaces in two-phase Titanium Aluminum Intermetallics
Authors: Wiezorek Jörg M.K. , Zhang Xiao-Dong , Fraser Hamish. L. 
Published: April 2011

AbstractThe role of slip transfer processes across the heterophase interfaces in two-phase TiAl intermetallics has been studied. Polysynthetically twinned crystals of TiAl (PST-TiAl) have been used as model systems for individual grains in technologically relevant polycrystalline lamellar TiAl alloys. Compressive plastic loads have been applied for orientations of the lamellar interfaces parallel and perpendicular to the loading directions to produce hard mode slip activity. Transmission electron microscopy has been used to determine the active deformation modes in the constituent phases and to study the slip transfer across heterophase interfaces. The results are discussed with respect to the mechanical behavior of PST-TiAl and lamellar TiAl alloys, which is of relevance to in-service performance and metallurgical processing operations.
Atomistic Simulations of Dislocation-Interface Interactions in Thin Films
Authors: Leger R. W. , Shen Y.-L. 
Published: April 2011

AbstractAtomistic simulations are carried out to study the effect of atomic sliding capability at the interface between a plastically deforming film and a stiff substrate. Molecular statics modeling is utilized to corroborate the overall film response and the nano-scale defect mechanisms. A free-sliding interface is shown to be able to cause “reflection” of oncoming dislocations and enhance film plasticity. A rigidly bonded interface, on the other hand, is seen to resist approaching dislocations. Partial sliding results in a transitional behavior between the two extremes, as revealed in our parametric analysis. The sliding capability of interface atoms is also seen to dictate the overall film response.
Modeling the Stress Evolution of Ion Beam Synthesized Nanocrystals
Authors: Yi D.O. , Sharp I. D. , Xu Q. , Liao C. Y. , Ager J. W. , Beeman J. W. , Liliental-Weber Z. , Yu K. M. , Zakharov D. , Haller E. E. , Chrzan D. C. 
Published: April 2011

AbstractUnder certain conditions, nucleation and growth can lead to substantial stresses in nanocrystals embedded in a host matrix. These stresses may be relaxed through subsequent annealing treatments. A model is presented for the relaxation of these stresses via diffusive processes within the matrix. The model reflects the effects of surface tension, potential phase transformations at or near the processing temperature, and differential thermal expansion. It is demonstrated that the model describes well the stress relaxation of ion beam synthesized Ge nanocrystals embedded in a silica matrix.
Atomistic Simulation of Dislocation Interactions with a σ = 5 (210) Grain Boundary during Nanoindentation of Ni
Authors: Jang Ho , Farkas Diana 
Published: April 2011

AbstractMolecular dynamics simulations of nanoindentation were performed using embedded atom potentials. The indentation was simulated on a Ni substrate using a diamond-like spherical indenter. In this study, we focused on the interaction of a σ=5 (210) grain boundary with the dislocations that were nucleated and expanded as loops under the indenter during nano- indentation. The results showed that dislocation loops were nucleated beneath the surface and propagated on multiple {111} slip planes. These dislocations impinged into the grain boundary in the course of nanoindentation. The lattice dislocations changed the atom configuration at the boundary region as they merged into the grain boundary and at later stages they transmitted across the grain boundary. The results also showed that the presence of a grain boundary affected the indenting speed and dislocation motion during nanoindentation, with the grain boundary retarding the indentation process.
Synthesis and Characterization of Fe-Co Nanocrystalline Alloys
Authors: Mujahid Mohammad , Zhu Jie 
Published: April 2011

AbstractNanostructured alloys have great potential as soft magnetic materials. In particular, nanocrystalline Fe-Co based alloys are believed to be good candidates for imparting improved magnetic behavior in terms of higher permeability, lower coercivity, reduced hysteresis losses and higher Curie temperatures. In the present work, Fe-50at.%Co alloy powders have been prepared using mechanical alloying (MA) in a planetary ball mill under controlled environment. The particle size and morphology of MA powders was investigated using scanning electron microscopy. The crystal size and internal strain was measured using X-ray diffraction. It has been shown that the crystal size could be reduced down to less than 15 nm in these alloys. Finally, the influence of grain size and internal strain on the magnetic properties has been discussed.
Microstructural Refinement in Single-Phase Copper Solid Solutions by Machining
Authors: Swaminathan S. , Chandrasekar S. , Compton W. D. , Trumble K. P. , King A. H. 
Published: April 2011

AbstractA study has been made of the effect of solute (Mn, Al, Ni) additions on microstructure refinement due to large strain deformation in single phase, copper solid solutions. The solutes were specifically selected for their influence on stacking fault energy (SFE) of copper, and the large strain deformation was imposed by chip formation in machining. The microstructure of Cu- 0.7at%Ni chip consists of elongated, sub-micrometer sized grains while Cu-7at%Al chip is made up of long, thin microbands with twins. The microstructure of the chip changes as the SFE of the material varies. With all of the solid solutions studied, the hardness of the chips is found to be significantly greater than that of the bulk material. Recrystallization temperature of solid solution chips is found to be higher than those of pure copper chips.
Effect of Oxygen and Nitrogen Doping on Mechanical Properties of Silicon Using Nanoindentation
Authors: Karoui A. , Rozgonyi G. , Ciszek T. 
Published: April 2011

AbstractThe effects of oxygen and nitrogen on the mechanical properties of Czochralski (CZ) and float zone silicon have been studied using nano-indentation. Nitrogen free FZ Si exhibited low hardness of 6.49 GPa and elastic modulus of 104 GPa. When doped with 2×1015cm−3 nitrogen, FZ Si hardness and elastic modulus increased to 8.2 and 182 GPa, respectively. In the near-surface denuded zone of N-doped CZ Si (N-CZ) the hardness correlates well with the O and N profiles. Distinct high hardness points, found in the O- and N- rich subsurface region, were attributed to precipitates. Nano-scratch tests of N-CZ Si confirmed the existence of hard phases, mostly small precipitates, whose density, estimated to be 2×1013cm−3, is in the range of previously suggested nuclei density in as-grown N-CZ silicon.
Critical Conditions for Dislocation Nucleation from Surface Steps
Authors: Li Chengzhi , Xu Guanshui 
Published: April 2011

AbstractThe critical conditions for dislocation nucleation from the surface steps of various geometries are analyzed based on the Peierls-Nabarro dislocation model. By modeling a surface step as part of a three- dimensional crack surface, the half space problem is transferred into an equivalent three dimensional crack problem in an infinite medium. The profiles of embryonic dislocations, corresponding to the relative displacements between the two adjacent atomic layers along slip planes, are then rigorously solved through the variational boundary integral method. The critical conditions for dislocation nucleation are determined by solving the stress dependent activation energies required to activate embryonic dislocations from their stable to unstable saddle point configurations. For a given slip plane, the effects of step geometry such as the step height and inclined angle on dislocation nucleation are analyzed in detail. The results show that the atomic scale steps may reduce the critical stress required for dislocation nucleation from the surface by several factors. Compared to previous analyses of this type of problem based on continuum elastic dislocation theory, the presented analysis eliminates the uncertain core cutoff parameter by allowing for the existence of an extended dislocation core as the embryonic dislocation evolves. Because of the serious limitation of direct atomic simulation for this type of problem, the presented methodology of incorporating atomic information into continuum approach appears to be particularly noteworthy for providing insights of energetics of the atomic processes involved in dislocation nucleation.
Investigation of Strain Accommodation upon Phase Transformation of Small Inclusions in Aluminum
Authors: Zhang L. H. , Johnson E. , Dahmen U. 
Published: April 2011

AbstractThe evolution of elastic strain caused by melting and solidification of small inclusions in aluminum was investigated by in-situ transmission electron microscopy. The appearance and subsequent decay of elastic strain during phase transformation of inclusions around 100nm in size were observed directly, and the decay rate was determined as a function of temperature. The mechanism of strain accommodation was studied by determining the activation energy of the process using alloy composition and inclusion size to control the transformation temperature.
Structures and Mechanical Properties of ECAP Processed 7075 Al Alloy upon Natural Aging and T651 Treatment
Authors: Zhao Yonghao , Liao Xiaozhou , Valiev Ruslan Z. , Zhu Yuntian T. 
Published: April 2011

AbstractEqual-channel angular pressing (ECAP) processed ultrafine grained (UFG) and coarse grained (CG) 7075 Al alloys were treated by natural aging and T651 temper (annealed at 120 °C for 48 h in Ar atmosphere), respectively. Mechanical tests showed that for the UFG sample, the natural aging resulted in the highest strength (the ultimate tensile strength is 720 MPa). In contrast, for the CG sample, the T651 treatment resulted in a higher strength (the ultimate strength is 590 MPa) than the natural aging (530 MPa). Microstructural analyses indicated that the enhanced strength of the T651 treated CG sample was mainly caused by high densities of G- P zones and metastable η' precipitates. The enhanced strength of the naturally aged UFG sample was mainly caused by the high densities of G-P zones and dislocations. Upon T651 treatment, the dislocation density of the UFG sample deceased significantly, overcompensating the precipitation strengthening.
A Formalism to Describe Demixing of Mixed Oxides of Large and Small Grain Size in an Electric Field
Authors: Belova Irina V. , Brown Mandy J. , Murch Graeme E. 
Published: April 2011

AbstractIn this paper, we address the theory of electric field demixing of the cations in semi-conducting and initially homogeneous mixed ceramic oxides. We include the off-diagonal phenomenological transport coefficients by assuming a random distribution of cations and making use of an exact sum-rule expression. The steady state atomic composition profiles are shown to be quite different when different assumptions are made about vacancy equilibration. We show that in the case of large grained material (where vacancies in the interior do not equilibrate easily to the external oxygen partial pressure), a maximum develops in the steady state vacancy composition profiles. This behaviour is verified by independent Monte Carlo simulations.
Surface structure and composition of nanocrystalline SnO2 thin films obtained by Chemical Vapor Deposition
Authors: Barreca Davide , Bontempi Elza , Depero Laura E. , Maragno Cinzia , Tondello Eugenio 
Published: April 2011

AbstractNanocrystalline SnO2 thin films were synthesized by Chemical Vapor Deposition on Si(100) and Al2O3 substrates using bis(diethylamino)dimethylstannane(IV) [(CH3)2Sn(N(C2H5)2)2] as precursor. Film growth was performed at 400-500°C in an O2(H2O)+N2 atmosphere, with the aim of studying the effects of the synthesis conditions on the coating properties. The sample chemical composition and surface morphology were analyzed by X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM), while their structural features were investigated by Glancing Incidence X-ray Diffraction (GIXRD) and X-ray Reflectivity (XRR). In this paper, the attention is focused on the interplay between film nanostructure and morphology, with particular regard to the influence of the growth surface.
Shape, Size and Morphology Control of Inorganic Crystals With Self-Assembled Monolayers
Authors: Han Yong-Jin , Aizenberg Joanna 
Published: April 2011

AbstractSelf-assembled monolayers (SAMs) provide simple, yet sophisticated surfaces to mimic the effect of proteins associated with the process of biomineralization. A careful selection of organic molecules with an appropriate surface chemistry (i.e. HS-(CH2)n-X−supported on a metal surface) allows the nucleation and growth of oriented calcite crystals and provides opportunities to study the formation of inorganic crystals assisted by organic molecules. We have successfully crystallized calcite crystals on different SAMs in the presence of additives such as proteins and/or ions in solution, and found correlations between the orientations of crystals to their final shapes, sizes and morphologies. We report here our experimental results demonstrating how underlying organic molecules along with inorganic additives can control and mold the final shape, size and morphology of calcium carbonate crystals
Interaction Between Titanium Implant Surfaces and Hydrogen Peroxide in Biologically Relevant Environments
Authors: Muyco Julie , Ratto Timothy , Orme Christine , McKittrick Joanna , Frangos John 
Published: April 2011

AbstractTitanium was exposed to dilute solutions of hydrogen peroxide (H2O2) to better characterize the interaction at the interface between the solution and metal. The intensity of light passing through films of known thickness of titanium on quartz was measured as a function of time in contact with H2O2in concentrations of 0.3% and 1.0%. An atomic force microscope (AFM) was used to record deflection-distance (force) curves as a probe approached the interface of titanium in contact with solution containing 0.3% of H2O2. The interaction layer measured using AFM techniques was much greater than the thickness of the titanium films used in this study. Raman spectroscopy taken during interaction shows the emergence of a Ti-peroxy gel and titania after 2 hours in contact with 0.3% H2O2solution.
Adhesion Kinetics of MC3T3-E1 Pre-Osteoblasts to Osteoconductive Porous Titanium Scaffolds
Authors: St-Pierre Jean-Philippe , Gauthier Maxime , Lefebvre Louis-Philippe , Tabrizian Maryam 
Published: April 2011

AbstractPorous metallic scaffolds have recently gained recognition as a promising avenue toward the regeneration of damaged bone structures. Interest in these materials resides in their ability to guide bone growth by presenting a favorable structure for cellular adhesion and three-dimensional proliferation. A powder metallurgy process to fabricate titanium foams with favorable microstructural parameters for applications in bone engineering has recently been developed. This study assesses the potential of this novel material for applications as an osteoconductive scaffold throughin vitrocharacterization of early cellular interactions with titanium foams having pore sizes ranging from 167 to 500 µm. The foams exhibit no cytotoxic effects on J774 mouse macrophages while favoring adhesion and proliferation of MC3T3-E1 pre-osteoblasts. Three-dimensional morphology assumed by these cells on porous titanium suggests that the microstructure of the foams is biomimetic.
Fabrication of Nanoporous Silica Nanospheres and Nanotubes by Inorganic and Organic Double Templates
Authors: Chen Jian-Feng , Liu Runjing , Cao Dapeng , Shen Zhigang , Yun Jimmy , Wang Jiexin , Shao Lei , Zhou Weilie L. 
Published: April 2011

AbstractInorganic and organic double templates were used to fabricate silica nanospheres and nanotubes with nanochannels perpendicular to the shells. Sphere and needle like CaCO3 nanoparticles, synthesized by a high gravity reactive precipitation method, were used as inorganic templates and C16H33N(CH3)3Br (C16-CTAB) was used as an organic surfactant template. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were employed to characterize the nanoporous structure. The nanochannels were found perpendicular to the surface of nanospheres and nanotubes. The size of nanochannels is about 3~5 nm. The size of hollow nanosphers and nanotubes can be controlled by the inorganic CaCO3 nanoparticle templates and the nanochannels in the shells can be tuned by different surfactant micelles. The nanospheres and nanotubes with nanochannels perpendicular to the shells have a potential application in chemical bio-catalyst, bio-separation, and drug delivery.