bluuebunny/crossref_metadata_2025_split huggingface dataset:
Routes towards large area, low pressure nanodiamond growth via pulsed microwave linear antenna plasma chemistry
Authors: Liehr Michael , Fendrych František , Taylor Andrew , Nesládek Miloš 
Published: April 2011

ABSTRACTCurrent experimental configurations for MW PECVD diamond growth do not allow simple up-scaling towards large areas, which is essential for microelectronic industries and other applications. Another important issue is the reduction of the substrate temperature during diamond growth to enhance the compatibility with wafer processing technologies. Such advantages are provided by MW-linear antenna (LA) plasma applicators, allowing a scalable concept for diamond growing plasmas. In the present work we introduce a novel construction of LA MW applicators designed for nanodiamond growth by using plasmas ranging from continuous wave (CW) to high repetition rates pulsed modes (up to 20 kHz) which advantages are discussed in detail.
Template-Assisted Fabrication of Double-Shelled Nanotubes Composed of Inner Shell Pb(Zr0.52Ti0.48)O3and Outer Shell TiO2by Sol-Gel Process with Spin-Coating Technique
Authors: Choi Y. C. , Cho S. Y. , Bu S. D. 
Published: April 2011

ABSTRACTDouble-shelled nanotubes composed of inner shell Pb(Zr0.52Ti0.48)O3(PZT) and outer shell TiO2are successfully fabricated by a spin coating of each sol-gel solution on porous anodic alumina template. Field emission transmission electron microscopy images show that they have a ~ 10 nm wall thickness. The selected area electron diffraction patterns show that they have two mixed crystalline phases of tetragonal PZT and anatase TiO2. The analyses of scanning transmission electron microscopy equipped with energy dispersive X-ray spectroscopy confirm their uniform distribution of each element.
Analysis of Vacancy Agglomeration Processes by Matusita’s Method for B2 FeAl
Authors: Yoshimi Kyosuke , Tsunekane Masafumi , Maruyama Kouichi 
Published: April 2011

ABSTRACTIn this study, the exothermic DSC peaks observed in rapidly-solidified Fe-44.9at.%Al ribbons and water-quenched Fe-48.5at.%Al single crystals were analyzed by Matusita’s method in order to discuss the kinetics of the agglomeration processes of supersaturated vacancies. Both the nucleation and morphological factors, n and m, respectively were approximately 3 for the rapidly solidified ribbons and were approximately 2 for the water-quenched single crystals. Based on the Matusita’s idea, the m values suggest the growth of 3-dimensional voids in the rapidly solidified ribbons and the growth of 2-dimensional dislocations loops in the single crystals due to the agglomeration of supersaturated vacancies. In addition, the n values suggest that the nuclei of voids and dislocation loops existed in as-quenched samples. These interpretations are in good agreement with the results of TEM observations.
Reaction Pathway Analysis of Homogeneous Dislocation Nucleation in a Perfect Molybdenum Crystal
Authors: Saeed Hasan A. , Izumi Satoshi , Hara Shotaro , Sakai Shinsuke 
Published: April 2011

ABSTRACTReaction pathway analysis was carried out for homogeneous dislocation nucleation in perfect crystal Mo. The reaction sampling method employed was based on the Nudged Elastic Band algorithm and other extended schemes. Results obtained were compared with corresponding results for Cu and Si. The stress range for activation energies less than 5 eV is found to be considerably higher for Mo than those for Cu as well as Si. Stresses in excess of 12 GPa make homogeneous dislocation nucleation in Mo an unrealistic transition. The results also show the dislocation cores under this stress range to be diffused, with shear displacement of particles being considerably less than the Burgers vector. Depending on the applied stress, displacement of extra slip-plane atoms can be considerable in Mo. This is in contrast to Cu, in which dislocation nucleation is essentially a two-plane phenomenon.
Enhanced Electron Field Emission from Carbon Nanotube Matrices
Authors: Pandey Archana , Prasad Abhishek , Yap Yoke Khin , Engelhard Mark , Wang Chongmin 
Published: April 2011

ABSTRACTField emission from as-grown carbon nanotube (CNTs) films often suffered from high threshold electric field, and low emission site density due to screening effects. These problems can be resolved by patterned growth of CNTs on lithographically prepared catalyst films. However, these approaches are expensive and not applicable for future emitting devices with large display areas. Here we show that as-grown CNTs films can have low emission threshold field and high emission density without using any lithography processes. We have reduced screening effects and work function of as-grown CNTs films and created the novel CNT matrices by addition of vapor- and/or liquid- phase deposition. Furthermore, these CNT matrices can continuous emit electrons for 40 hours without significant degradation. The fabrication of our CNT matrices is described as follows. First, CNT films were grown by plasma-enhanced chemical vapor deposition. These vertically-aligned multiwalled carbon nanotubes (VA-MWCNTs) are having typical length and diameter of 4 microns and 40 nm, respectively. Spacing between these CNTs is ~80 nm in average, leading to poor emission properties due to the screening effect. These as-grown samples were then subjected to the deposition of strontium titanate (SrTiO3) by pulsed-laser deposition to reduce both the work function and screening effect of CNTs. The emission properties of these coated samples can be further improved by fully filled the spaces between VA-MWCNTs by poly-methyl metha acrylate (PMMA). The field emission threshold electric field was decreased from 4.22 V/μm for as-grown VA-MWCNTs to 1.7 V/μm for SrTiO3 coated VA-MWCNTs. The addition filling with PMMA and mechanical polishing can further reduce the threshold to 0.78V/μm for the so called PMMA-STO-CNT matrices. Long term emission stability and emission site density were also enhanced.
Characterization of Curvature in CNT Turf Structures from Two-Dimensional Images
Authors: Kelley Garrett M. , Field David P. 
Published: April 2011

ABSTRACTCarbon nanotube turfs are collections of nanotubes in a turf or mat assembly with potential application as thermal switches, flat panel displays, hard drives, sensors, etc. The nano-topology of the turf necessarily relates to the turf properties; electrical, thermal, optical, etc. A simple method to quantitatively characterize the density, tortuosity and path connectedness of the turfs using secondary electron imaging was previously developed. The present work aims at developing the groundwork for a more realistic measure of tortuosity by using a deterministic approach to obtain the radii of semi-circular tubes as observed in projected images.
Grating Coupled Waveguide Biosensor Based on Porous
Silicon
Authors: Wei Xing , Weiss Sharon M. 
Published: April 2011

ABSTRACTPorous silicon waveguides with integrated porous silicon grating couplers
are demonstrated as small molecule biosensors. Two fabrication methods are
presented for the grating couplers: standard electron beam lithography with
reactive ion etching and a new technique based on direct imprinting of
porous substrates. Although the gratings fabricated using standard
lithographic techniques have steeper sidewalls and enable a larger available
sensing surface area inside the waveguide, the imprinted gratings have the
advantage of rapid and low-cost fabrication. Both the lithographically and
imprinted sensors are shown to have waveguide losses on the order of 10
dB/cm, and both are demonstrated for detection of 16mer nucleic acids.
Assessment of the Phase Equilibria among γ-Fe/ Fe2Nb/ Ni3Nb Phases in Fe-Ni-Nb Ternary System at Elevated Temperatures
Authors: Hasebe Y. , Hashimoto K. , Matsuo T. , Takeyama M. 
Published: April 2011

ABSTRACTPhase equilibria among γ-Fe, ε-Fe2Nb Laves and δ-Ni3Nb phases in Fe-Ni-Nb ternary system at 1473 K and 1373 K were experimentally examined, and also assessed by calculation in order to calculate the phase equilibria among these phases at 973 K. A ternary compound with hP24 structure with its limited composition range of Fe-21.5Nb- (56.8-59.8) Ni exists between Fe2Nb and Ni3Nb phase regions at both temperatures. Including the hP24 phase, the calculated isotherms at both temperatures are in good agreement with experimental ones. By using the optimized interaction parameters among the three elements in each phase, the isothermal section calculated at 973 K revealed a γ-Fe+ Fe2Nb + Ni3Nb three-phase coexisting region extended to Fe-rich composition of 80 at. % Fe. This suggests a possibility to develop austenitic heatresistant steels strengthened by both intermetallics phases.
Novel Concept of Creep Strengthening Mechanism using Grain Boundary Fe2Nb Laves Phase in Austenitic Heat Resistant Steel
Authors: Tarigan Imanuel , Kurata Keiichi , Takata Naoki , Matsuo Takashi , Takeyama Masao 
Published: April 2011

ABSTRACTThe creep behavior of a new type of austenitic heat-resistant steel Fe-20Cr-30Ni-2Nb (at.%), strengthened by intermetallic Fe2Nb Laves phase, has been examined. Particular attention has been given to the role of grain boundary Laves phase in the strengthening mechanism during long-term creep. The creep resistance increases with increasing area fraction (ρ) of grain boundary Laves phase according to equation ε/ε = (1−ρ), where ε0 is the creep rate at ρ = 0. In addition, the creep rupture life is also extended with increasing ρ without ductility loss, which can yield up to 77% of elongation even at ρ = 89%. Microstructure analysis revealed local deformation and well-developed subgrains formation near the grain boundary free from precipitates, while dislocation pile-ups were observed near the grain boundary Laves phase. Thus, the grain boundary Laves phase is effective in suppressing the local deformation by preventing dislocation motion, and thereby increases the long-term creep rupture strength. This novel creep strengthening mechanism was proposed as “grain boundary precipitation strengthening mechanism” (GBPS).
Evaluation of adhesive strength between vanadium alloys and yttrium oxide by laser shock spallation method
Authors: Satou M. , Akamatsu H. , Nagasaka T. , Hasegawa A. 
Published: April 2011

ABSTRACTAdhesive strength between V-4Cr-4Ti type alloys and an yttrium oxide layer formed by a plasma spray technique was evaluated by a laser shock spallation method, which uses a pulse laser to generate a shock wave to create tensile stress inside the specimen. There was no significant dependence of the adhesive strength on the alloying elements examined, such as yttrium, silicon and aluminum. Detailed observation of the exfoliation behavior was carried out to identify the weakest interface of the coating layer. Several modes of exfoliation behavior were categorized after cross-sectional observation. There was some uncertainty of the adhesive strength of the layer evaluated by the laser shock method, due to the thickness of the coating layer. The typical adhesive strength between the alloy and yttrium oxide layer was evaluated to be approximately 400 MPa.
Failure mode transition in natural mineralized
composites
Authors: Rabiei Reza , Bekah Sacheen , Barthelat Francois 
Published: April 2011

ABSTRACTMineralized biological materials such as nacre and bone achieve remarkable
combinations of stiffness and toughness through staggered arrangements of
stiff components bonded by softer materials. These natural composites are
therefore substantial source of inspiration for emerging synthetic
materials. In order to gain new insights into structureperformance
relationships of these staggered structures, nacres from four species were
compared in terms of fracture toughness and damage propagation pattern.
Fracture tests revealed that all nacres display rising crack resistance
curves, but to different extents. Using in-situ optical and atomic force
microscopy, two distinct patterns of damage propagation were identified in
columnar and sheet nacre respectively. These two different patterns were
further confirmed by means of large scale numerical models of staggered
structures. Similar mechanisms possibly operate at the smallest scales of
the microstructure of bone.
Simulation of the Mechanical Behavior of White Matter Using a
Micromechanics Finite Element Method
Authors: Pan Yi , Pelegri Assimina A. , Shreiber David I. 
Published: April 2011

ABSTRACTThe atypical mechanical behavior of white matter and its influence on the
mechanical properties of brain tissue necessitate adoption of a mutli-scale
model of white matter for accurate computational analysis. Herein, we
present a micromechanical analysis coupled with finite elements into a
biomechanical interacting model of white matter. A representation of the
white matter of central nervous system is identified and its microstructure
is generated. The geometric descriptions of the axon and the surrounding
matrix are obtained from neurofilament immunohistochemistry images.
Consecutively, linear elastic material constitutive models are applied to
describe the behavior of axons and their surrounding matrix subjected to
small deformations. This model facilitates determination of the tissue’s
stress and strain fields, and enables an understanding of the effects of
axon undulation on local fields. The fundamental nature of the model enables
future scale-up for structural tissue analysis and predictions of axon
damage at the microscale.
Mg-Ti: A Possible Biodegradable, Biocompatible, Mechanically Matched Material for Temporary Implants
Authors: Hoffmann Ilona , Cheng Yang-Tse , Puleo David A. , Song Guangling , Waldo Richard A. 
Published: April 2011

ABSTRACTIn recent years there has been a renewed interest in magnesium alloys for applications as temporary biomedical implants because magnesium is both biocompatible and biodegradable. However, the rapid corrosion rate of magnesium in physiological environments has prevented its successful use for temporary implants. Since alloying is one of the routes to slow down corrosion, we report in this publication our investigation of Mg-Ti alloys fabricated by high-energy ball milling as possible materials for biocompatible and biodegradable implants. Titanium was chosen mainly because of its proven biocompatibility and corrosion resistance. Corrosion tests carried out by immersing the Mg-Ti alloys in Hank’s Solution at 37°C showed significantly improved corrosion resistance of the alloy in comparison to pure magnesium. Thus, Mg-Ti alloys are promising new biodegradable and biocompatible materials for temporary implants.
Simulations of Stretching Single Stranded DNA
Authors: Singh Abhishek , Yingling Yaroslava G. 
Published: April 2011

ABSTRACTMolecular dynamics simulations were performed to estimate sequence dependent
force required to stretch single stranded DNA (ssDNA) homo oligonucleotides.
Simulations suggest that polyA and polyC oligonucleotides exhibit similar
force profiles and corresponding elongation. Among single stranded DNA
strands polyT is the most flexible and needs the most force to unwind from
an equilibrium folded structure. In contrast, polyG had a very small
recoverable deformation prior to a non-linear stretching. Our results
indicate that mechanical properties of ssDNA chains are directly related to
their sequence.
A Macroscale Biomimetic Composite Duplicating the Deformation
Mechanisms of Nacre
Authors: Zhu Deju , Barthelat Francois 
Published: April 2011

ABSTRACTThis article presents the first man-made material based on the structure of
nacre that successfully duplicates the mechanism of tablet sliding. This
material was made of millimeter size PMMA tablets arranged in columns and
held by fasteners. Strain hardening was provided by tablet waviness,
delaying localization and leading to strains at failure 3-5 times greater
than bulk PMMA. Analytical and finite element models successfully captured
the locking mechanisms, enabling a rigorous design and optimization of
similar composites based on different materials or at different length
scales. This work demonstrates how key features and mechanisms in natural
nacre can be successfully harnessed in engineering materials. Interestingly,
the development of this model material and of its associated models also
unveiled two new mechanisms, the effect of free surfaces and “unzipping”.
Both mechanisms may be relevant to natural materials such as nacre or
bone.
Quantifying Micro-mechanical Properties of Soft Biological
Tissues with Scanning Acoustic Microscopy
Authors: Zhao Xuegen , Wilkinson Steven , Akhtar Riaz , Sherratt Michael J , Watson Rachel E B , Derby Brian 
Published: April 2011

ABSTRACTIn this study we have established a new approach to more accurately map
acoustic wave speed (which is a measure of stiffness) within soft biological
tissues at micrometer length scales using scanning acoustic microscopy. By
using thin (5 μm thick) histological sections of human skin and porcine
cartilage, this method exploits the phase information preserved in the
interference between acoustic waves reflected from the substrate surface as
well as internal reflections from the acoustic lens. A stack of images were
taken with the focus point of acoustic lens positioned at or above the
substrate surface, and processed pixel by pixel using custom software
developed with LABVIEW and IMAQ (National Instruments) to extract phase
information. Scanning parameters, such as acoustic wave frequency and gate
position were optimized to get reasonable phase and lateral resolution. The
contribution from substrate inclination or uneven scanning surface was
removed prior to further processing. The wave attenuation was also obtained
from these images.
Atomic Force Microscopic Study of Morphological Changes for
Treated and Untreated Collagen Fibers of Mongolian Goatskins
Authors: Ankhbayar Enkhbaatar , Itgel Byamba , Batkhuu Byambadembrel , Urnaa Dashnyam , Ganzorig Chimed 
Published: April 2011

ABSTRACTIn this study, the morphological changes of chemically treated (or
preserved) with aqueous solutions of 1) a sodium chloride (NaCl) and 2) a
compound containing sodium silicate, so called “wasserglass”, and untreated
I-type collagen fibers of Mongolian goatskin are investigated by atomic
force microscopy in ambient condition and at room temperature. The
experimental results show that the difference between D period for both
chemically treated and untreated collagen fibers are a relatively stable for
morphological behavior. However, we find that the width of collagen fibers
treated with the NaCl solution is more increasing with approximately 112 nm
than those of samples (untreated and treated with wasserglass solution) for
the range 93.4-94.8 nm. We also observe that a typically structure of the
collagen fibers generally, a dense packing of the untreated and treated by
wasserglass collagen fibers in bundles in a nearly parallel arrangement,
with little changes in orientation can be seen. The collagen fibers treated
by NaCl are a more destructive than untreated and treated by wasserglass for
collagen fibers.
Glucose Oxidase-Functionalized Nanodiamond Films for Biosensor Application
Authors: Villalba Pedro , Ram Manoj K. , Gomez Humberto , Kumar Amrita , Bhethanabotla Venkat , Kumar Ashok 
Published: April 2011

ABSTRACTThe importance of nanodiamond in biological and technological applications has been recognized, and applied in drug delivery, biochip, sensors and biosensors. Nanodiamond (ND) and nitrogen doped nanodiamond (NND) films were deposited on n-type silicon films, and later functionalized with enzyme glucose oxidase (GOX). Functionalized electrode has been characterized using different techniques; i.e.fourier transform spectroscopy (FTIR) -, Raman spectroscopy, atomic force microscopy (AFM) and electrochemical techniques, respectively. Under this work, the ND/GOX and NND/GOX electrodes have demonstrated providing sensitive glucose concentration response. Besides, the cytotoxic effects of the NDs have been studied in vitro. Human Embryonic Kidney 293 (HEK293) cells are cultured in the presence of the films then toxicity has been detected using MTT-based cytotoxicity assays utilizing 3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT). The final results for MTT assays are quantified by spectrophotometry using a plate reader at 570 nm As-prepared nanodiamond has been found to be stable , biocompatible and useful for biosensing applications. A linear response of the enzyme based electrode to glucose concentration is also observed from 1-8 x mM before saturation condition close to 10mM has been observed.
Electrical Conducting Diamond Thin-Films: An Alternative Counter Electrode Material for Dye Sensitized Solar Cells
Authors: Vispute R.D. , Vats Alok , Venkatesan Vinod , Seiser Andrew , Dozier Jaurette , Feldman Jeremy , Robinson Lance 
Published: April 2011

ABSTRACTCarbon is a favorable alternative as counter electrode material for dye sensitized solar cells (DSSC) as compared to Pt. Various carbon materials such as carbon nanotubes (CNT), activated carbon (AC) and carbon nanofibers have been investigated as counter electrodes for DSSC applications, based on their high electrochemical activity, high specific surface area, chemical inertness and high electrical conductivity. Among various phases of carbon, diamond is the most robust and chemical inert material that can be used for electrode application. It has band gap of 5.5 eV, high thermal conductivity. its electrical resistivity can be tuned by doping such as boron. In this work, we investigate boron doped diamond thin film electrode for DSSCs. The conductive diamond thin electrode films were grown using Blue Wave hot wire chemical vapor deposition (HWCVD) system. The electrical resistance in diamond thin films was tuned by controlling grow temperature, filament power, dopant concentration and sp3/sp2 ratio in the film, it thickness, and initial seeding process. Scanning electron microscopy, Raman spectroscopy and electrical resistivity measurement were used to characterize morphology, diamond quality and electrode conductivity, respectively. Diamond film electrodes with optimized surface morphology and electrical characteristics were used for DSSC fabrication. We used nanocrystalline TiO2 paste (P25 Degussa) with average particle size of 25nm as an active layer, the electrolyte comprised of a LiI/I2 electrolyte in acetonitrile (CH3CN), a Ru based metal complex dye [cis-diisothiocyanato-bis(2,2’-bipyridyl-4,4’-dicarboxylato) ruthenium(II) bis(tetrabutylammonium)] OR N719 was used as sensitizer. The photovoltaic performance was determined using J-V characteristics under standard illumination conditions and was compared to a reference DSSC with Pt counter electrode. Results are discussed in the context of diamond electrical and durability and chemical stability of diamond films against most commonly used family of iodine based electrolytes.
CVD-Grown Graphene Solution-gated Field Effect Transistors for pH Sensing
Authors: Giacchetti Benjamin Mailly , Hsu Allen , Wang Han , Kim Ki Kang , Kong Jing , Palacios Tomas 
Published: April 2011

ABSTRACTThis paper presents the fabrication technology and initial characterization of electrolyte-gated field effect transistor (FET) arrays based on CVD grown graphene on copper. We show that the graphene FET (GFET), when immersed in electrolytes, exhibit a transconductance around 5 mS/mm. From preliminary pH sensing experiments, a pH sensitivity of 24 mV/pH has been demonstrated.