bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cross-sectional TEM study of surface modification of nano-structure with gas cluster ion beams
Authors: Toyoda Noriaki , Yamada Isao 
Published: April 2011

ABSTRACTSurface modification effects on patterned surface with gas cluster ion beam (GCIB) were studied by observation with a cross-sectional transmission electron microscope in order to use it for planarization of patterned media such as discrete track media (DTM) or bit-patterned media (BPM) for future hard disk drives. As a model structure of patterned media, line-and-space or bit patterns were fabricated on Si substrates, and subsequently amorphous carbon films were deposited on them. After Ar-GCIB irradiations on amorphous carbon, it was shown that GCIB preferentially removed bumps or crest on the surface of amorphous carbon at normal incidence. The required thickness for planarization was close to the initial peak-to-valley. At an incident angle of 57°, line-and-space patterns became sharp-pointed shape. On the contrary, line-and-space patterns were planarized without tiny asperity formation at 77°. These results indicate that quite effective planarization of patterned surface is possible using GCIB at normal or glancing angle irradiation.
Defect doping and characterization in oxide single crystals using femtosecond laser
Authors: Kanehira Shingo , Moon Chiwon , Tochigi Eita , Shibata Naoya , Ikuhara Yuichi , Miura Kiyotaka , Hirao Kazuyuki 
Published: April 2011

ABSTRACTDefects inside oxide ceramics of magnesium oxide (MgO) and sapphire (Al2O3) were formed using femtosecond laser irradiation. The laser irradiance in these ceramics forms various defects classified as dislocations, twins, or nano cracks near the focal point due to the increase of temperature and successive generation of shockwave within several picoseconds. The morphology of defects mainly depends on the crystal structure; dense dislocations inside MgO with a rock-salt type structure, and nanocracks, dislocations, or twins in sapphire with a corundum structure. The TEM analysis revealed that the dense dislocations formed on the two slip planes {110} to form a cross-shaped pattern when the laser beam focused on the (100) plane in MgO. In case of sapphire crystal, cracks propagated from the focal point that has an amorphous structure along R-planes {11-02}, which had the lowest fracture surface energy. The nano crack transformed into the aligned void and dislocation structure during the heat treatment over 1573K, which is one of the crack healing effect.
Nanostructured Engineering Alloys for Nuclear Application
Authors: Hosemann Peter , Stergar Erich , Nelson Andrew T. , Vieh C. , Maloy Stuart A. 
Published: April 2011

ABSTRACTIn advanced nuclear applications, high temperature and a corrosive environment are present in addition to a high dose radiation field causing displacement damage in the material. In recent times it has been shown that Nanostructured Ferritic Alloys (NFA’s) such as advanced Oxide Dispersion Strengthened (ODS) steels are suitable for this environment as they tolerate high dose irradiation without significant changes in microstructure or relevant mechanical properties.Ion beam irradiation is a fast and cost effective way to induce radiation damage in materials but has limited penetration depth. Therefore, small scale mechanical testing such as nanoindentation and micro compression testing in combination with FIB based sample preparation for micro structural characterization has to be performed allowing a full assessment of the materials’ behavior under radiation environment. In this work two different ODS materials have been irradiated using proton and combined proton and He beams up to 1 dpa at different temperatures. Nanoindentation and LEAP measurements were performed in order to assess the changes in properties of these alloys due to irradiation. The same techniques were applied to intermetallic nanostructured alloys in order to investigate the effectiveness of the metal-intermetallic interface to provide defect sinks for He and radiation damage. It was found that irradiation can cause the formation of intermetallic particles even at room temperature while increasing the material strength significantly.
Comparison of CVD and MOCVD-grown Al2O3 coatings in the performance of cemented carbide cutting tool inserts
Authors: Jaiswal Piyush , Sathar Abdul , Shariff Arshiyan , Saif Mohammed , Dhar Sukanya , Shivashankar S. A. 
Published: April 2011

ABSTRACTLow-pressure MOCVD, with tris(2,4-pentanedionato)aluminum(III) as the precursor, was used in the present investigation to coat alumina on to cemented carbide cutting tools. To evaluate the MOCVD process, the efficiency in cutting operations of MOCVD-coated tools was compared with that of tools coated using the industry-standard CVD process.Three multilayer cemented carbide cutting tool inserts, viz., TiN/TiC/WC, CVD-coated Al2O3 on TiN/TiC/WC, and MOCVD-coated Al2O3 on TiN/TiC/WC, were compared in the dry turning of mild steel. Turning tests were conducted for cutting speeds ranging from 14 to 47 m/min, for a depth of cut from 0.25 to 1 mm, at the constant feed rate of 0.2 mm/min. The axial, tangential, and radial forces were measured using a lathe tool dynamometer for different cutting parameters, and the machined work pieces were tested for surface roughness. The results indicate that, in most of the cases examined, the MOCVD-coated inserts produced a smoother surface finish, while requiring lower cutting forces, indicating that MOCVD produces the best-performing insert, followed by the CVD-coated one. The superior performance of MOCVD-alumina is attributed to the co-deposition of carbon with the oxide, due to the very nature of the precursor used, leading to enhanced mechanical properties for cutting applications in harsh environment.
Responses of Carbon Onions to High Energy Heavy Ion Irradiation
Authors: Alduhaileb Raed A. , Xie Kan , Myers Joshua C. , Ayres Virginia M. , Jacobs Benjamin W. , McElroy Kaylee , Bieler T. , Crimp M. , Fan Xudong , Ronningen Reginald M. , Zeller Albert F. , Baumann Thomas , Hirata Atsushi 
Published: April 2011

ABSTRACTWe report evidence for graphene layer rearrangements in heavy ion interactions with carbon onions at 140 MeV and 70 MeV per nucleon kinetic energies. Graphene layer rearrangements have been recently predicted in spherical and cylindrical multi-layer graphene systems. The implications of graphene layer rearrangement on the tribological performance of multi-layer nano-carbons in extreme environments are discussed.
Effect of Seawater on Thermal Behavior of Conventional and Nanophased Carbon/Epoxy Composites
Authors: Hossain Mohammad K , Imran Kazi A , Hosur Mahesh , Jeelani Shaik 
Published: April 2011

ABSTRACTThe effect of seawater on thermal behavior of conventional and nanophased carbon/epoxy composites was investigated in this study. Composites were fabricated with 1 wt.%, 2 wt.%, and 3 wt.% nanoclay by vacuum assisted resin transfer molding (VARTM) process and compared with neat samples with and without exposure to seawater. Thermal characterization was performed by the dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). Samples exposed to the seawater for 30- and 60-day periods revealed that samples with nanoclay retained better thermal properties compared to the neat samples. Storage modulus was reduced by 6.28%, 6.76%, 6.15%, and 7.05% for neat, 1 wt.%, 2 wt.%, and 3 wt.% nanoclay infused samples, respectively, after the samples were exposed to seawater for 60 days . From TGA results, it was observed that the thermal stability is not related to nanoclay content and conditoning. Optical microscope (OM) and scanning electron microscope (SEM) studies revealed no significant change in surface morphology in the 30-day conditioning samples.
Dynamics of Charge Transfer Excitons Recombination in
Polymer/Fullerene Solar Cells
Authors: Hallermann Markus , Deschler Felix , Berger Josef , von Hauff Elizabeth , Da Como Enrico 
Published: April 2011

ABSTRACTAmong the different recombination mechanisms in organic solar cells the
photoluminescence (PL) of charge transfer excitons (CTEs) has been
identified has one of the most important, impacting both the open circuit
voltage and the short circuit current. Here, we study their recombination
dynamics, monitoring the decay of the PL on a time scale spanning three
orders of magnitude from nanoseconds to microseconds. As a model system we
investigate blends of the conjugated polymer
poly(2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene-vinylene) (MDMO-PPV)
and the fullerene derivative [6,6]-phenyl C61-butyric acid methyl
ester (PCBM). We observe that the dynamics of recombination follows a
power-law, which is independent of sample morphology. Upon application of a
transient electric field, which is capable of separating the bound charge
pairs, we observe different dynamics of recombination only for the separated
pairs. Those also follow a power-law and show a strong dependence on the
film morphology.
Krypton and Helium Irradiation Damage in Yttria-stabilised Zirconia
Authors: Gilbert M. , Davoisne C. , Stennett M. C. , Hyatt N. C. , Peng N. , Jeynes C. , Lee W. E. 
Published: April 2011

ABSTRACTA candidate matrix material for inert matrix fuel (IMF), yttria-stabilised zirconia (YSZ) has been doped with Nd3+ as a surrogate for Pu3+. To simulate and assess the effects of fission gas accommodation and alpha decay on the microstructure, samples of (Y0.1425,Nd0.05,Zr0.8075)O1.904 have been irradiated with 2 MeV 36Kr+ ions, at fluences of 1×1014 and 5×1015 cm−2, and 200 keV 4He+ ions at fluences of 1×1014, 5×1015 and 1×1017 cm-2. Analysis by transmission electron microscopy (TEM) of thin sections prepared by focussed ion beam (FIB) milling revealed damage was only observed at the highest 36Kr+ and 4He+ fluences. Monte Carlo simulations using the TRIM code showed that it is only at these fluences that the level of atomic displacements was sufficient to result in observable defect cluster formation within the material.
PEG-Assisted Hydrothermal Synthesis and Photocatalytic Activity of Bi2Fe4O9 Crystallites
Authors: Cai Dengrong , Li Jianmin , Bu Shundong , Yu Shengwen , Jin Dengren , Cheng Jinrong 
Published: April 2011

ABSTRACTA facile hydrothermal route assisted by polyethylene glycol (PEG) 400 was utilized to synthesize single-phase Bi2Fe4O9 crystallites. X-ray diffraction results showed the products with PEG 400 of 30 g/L exhibited a preferred growth along the (001) plane. Transmission electron microscopy indicated that the morphology of the as-prepared Bi2Fe4O9 crystallites with PEG 400 were plake-like and rod-like. Strong absorption in visible-light region of the products was characterized by UV-vis diffuse reflectance spectrum (UV-DRS). The photocatalytic activity of Bi2Fe4O9 crystallites was evaluated on degradation of methyl orange (MO) under visible light irradiation. For 3 h irradiation, the degradation ratio was increased to 93% with the aid of a small amount of H2O2. The analysis of FT-IR spectra proved that the Bi2Fe4O9 catalysts were remained stable after the photocalytic reactions.
Atomistic study of the mechanical properties of metallic-glass nanowires
Authors: Koshiyama K. , Shintani K. 
Published: April 2011

ABSTRACTMelt-growth simulations based on the molecular-dynamics method for both the Cu-Zr and Ni-Al crystalline nanowires of B2 structure are performed to produce metallic-glass nanowires of amorphous structure. Next, tensile deformations of these nanowires are simulated at various temperatures. For the sake of comparison, Cu-Zr and Ni-Al crystalline nanowires of B2 structure are also elongated. It is revealed that the tensile strength of the metallic-glass nanowires is third or fourth of the tensile strength of the crystalline nanowires. Increasing tensile strain, the Cu-Zr crystalline nanowires of B2 structure change their structure twice, whereas the metallic-glass nanowires only decrease their thicknesses locally, and necking takes place.
Large Self-Assembled Peptide Fibers
Authors: Barone Justin R. , Athamneh Ahmad 
Published: April 2011

ABSTRACTMany systems, including peptide systems, have been identified that
self-assemble into nanometer sized structures. However, continued
self-assembly to the macroscopic scale has remained elusive even though
nature routinely does it. Here, a unique hierarchical peptide self-assembly
process is described from the nanometer to the micrometer scale.
Anomalous Behavior of Polystyrene Blends Using Thermally Induced
Surface Wrinkling
Authors: Torres Jessica M. , Vogt Bryan D. 
Published: April 2011

ABSTRACTThe wrinkling of a 50:50 blend of a high molecular mass (Mn = 990
kg/mol) and low molecular mass (Mn = 1.3 kg/mol) polystyrene (PS)
film is studied as a function of annealing temperature and film thickness.
Both thermal and mechanical wrinkling are utilized to elucidate the apparent
modulus of these PS blend films. The PS blend shows a modulus comparable to
the high molecular weight PS, ≈ 3.2 GPa for mechanical wrinkling at ambient
and thermal wrinkling for T ≤ 50 °C. A sharp decrease in the apparent
modulus of the film occurs when thermal wrinkling occurs at 60 °C or higher.
The calculated modulus in this case is 0.5 GPa, which is significantly below
the modulus determined the neat PS for either Mn when thermally
wrinkled at T > 60 °C. This behavior is attributed to a combination of
surface segregation of the low molecular weight PS as well as the large
difference in bulk glass transition temperature (Tg) of each
component. During thermal wrinkling, the high Mn PS vitrifies
first, while the surface containing primarily low Mn PS is
rubbery; this leads to only the underlayer of PS wrinkling initially and
selection of a shorter wavelength due to the effective thickness. The
increased thermally induced stresses during cooling when the low
Mn PS is vitrified do not change the selected wavelength and
instead only leads to an increase in the wrinkle amplitude. These results
illustrate a potential method to modulate the wrinkle wavelength without
changing the overlayer, which could be useful for patterning
applications.
First-Principles Investigation of Structural, Elastic and Electronic Properties of Lanthanide Titanate Oxides Ln2TiO5
Authors: Niu Hui , Gou Huiyang , Ewing Rodney C. , Lian Jie 
Published: April 2011

ABSTRACTSystematic first-principles calculations based on density functional theory were performed on a wide range of Ln2TiO5 compositions (Ln = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy and Y) in order to understand the correlation between structural, elastic and electronic properties. A complete set of elastic parameters including elastic constants, Hill’s bulk moduli, shear moduli, Young’s moduli and Poisson’s ratio, were calculated. All Ln2TiO5 are ductile in nature, and analysis of densities of states and charge densities suggests that the oxide bonds are highly ionic.
HIGH FREQUENCY TOP-GATED GRAPHENE RF AMBIPOLAR FETs USING LARGE-AREA CVD GRAPHENE AND ADVANCED DIELECTRICS
Authors: Nayfeh Osama M. , Dubey Madan 
Published: April 2011

ABSTRACTAmbipolar top-gated field effect transistors (FETs) based on large area Cu catalyzed CVD-grown monolayer graphene interfaced to advanced dielectrics have been constructed and examined both for their material and electrical qualities. Interfacing of the graphene with novel insulators/substrates could be tailored for the particular application and provide for enhanced device functionality. In contrast to graphene FETs using SiO2-based top-gate dielectric, which show asymmetric electron/hole mobility (with larger hole mobility), and Dirac point shifted to positive levels, FETs constructed using advanced AlN show Dirac point almost near neutral levels and near symmetric electron/hole mobility. The DP is shifted likely due to compensation of the intrinsic p-type doping by n-type doping introduced by the AlN deposition and potentially via a contribution of polarization-induced carrier density. Finally, we demonstrate a top-gated graphene FET with the first observation of RF operation with GHz cut-off frequency based on large area CVD graphene.
Enhancing the photo-oxidation resistance of PPV-type polymers:
effect of a radical scavenger addition
Authors: Ferreira G. R. , Nowacki B. , de Azevedo E. R. , Akcelrud L. C. , Bianchi R. F. 
Published: April 2011

ABSTRACTA hindered phenol type radical scavenger (Irganox 1010®) was used to improve
the resistance to photo-oxidation in PPV-type polymers. The degradation was
performed under blue light (460 nm), and the effect of the added compound
was investigated following the intensity variation of absorbance and
photoluminescence spectra. The results showed that the addition of the
compound brought about a significant enhancement in photodegration
resistance without interfering in the electronic properties of the polymers.
These results suggest that the free radical scavenger attenuates the
decrease of the polymer conjugation length induced by the radiation. FTIR
measurements confirm this evidence.
Heterogeneous integration of Polymer Porous Photonic Bandgap
Structure with Xerogel based Biochemical Sensors
Authors: Xu Huina , Liu Ke , Yung Ka Yi , Bright Frank V. , Cartwright Alexander N. 
Published: April 2011

ABSTRACTWe report the heterogeneous integration of a multifunctional sensor based on
polymer porous photonic bandgap (P3BG) structure and xerogel
based luminescence sensor technology. The P3BG structure was
fabricated using holographic interferometry. Initially, holographic
interferometry of a photo-activated prepolymer syrup that included a
volatile solvent as well as monomer, photoinitiator, and co-initiator was
used to initiate photopolymerization. Subsequent UV curing resulted in well
defined lamellae of the polymer separated by porous polymer regions that
created a high quality photonic bandgap structure. The resulting
P3BG structure was then integrated with the xerogel based
luminescence element to produce a luminescence sensor with a selective
narrow band reflector. The prototype xerogel based luminescence sensor
element consisted of an O2 sensing material based on spin coated
tetraethylorthosilane (TEOS) composite xerogel films containing tris
(4,7-diphenyl-1,10-phenanthroline) ruthenium (II)
([Ru(dpp)3]2+) luminophore. We demonstrated
enhancement of the signal-to-noise ratio (SNR) of this integrated
multifunctional sensor while maintaining the same sensitivity to
O2 sensing of the xerogel based element. The resulting
advantages and enhanced SNR of this integrated sensor will provide a
template for other luminescence based assays to support highly sensitive and
cost-effective sensor systems for biomedical applications.
Integrating Colloidal Quantum Dots with Porous Silicon for High
Sensitivity Biosensing
Authors: Gaur Girija , Koktysh Dmitry , Weiss Sharon M. 
Published: April 2011

ABSTRACTWe aim to utilize the high surface area of a porous silicon (PSi) matrix
coupled with semiconductor quantum dot (QD) amplifiers for ultrasensitive
optical detection of small biomolecules using a dual-mode detection scheme.
In our system, QDs attached to the target biomolecule serve as signal
amplifiers by providing an additional refractive index increase beyond that
of the smaller target molecules. The strong photoluminescence (PL) from the
QDs serves as a secondary indication of target molecule attachment in the
pores. A resulting increase in optical thickness of ∼190 nm and detection
sensitivity of ∼700 nm/RIU have been demonstrated for attachment of
glutathione capped CdTe QDs in the porous silicon matrix. Reflectance and PL
measurements, combined with simulations, have been used to characterize the
surface area coverage of the QDs within the porous framework, which is
estimated at 10% for glutathione capped CdTe QDs.
Kinetics of crystallization of biodegradable PHA copolymers: a combined X-ray scattering and micro-indentation study
Authors: Domínguez-Díaz Maraolina , Flores Araceli , Romo-Uribe Angel , Cruz-Silva Rodolfo 
Published: April 2011

ABSTRACTWide Angle X-ray scattering (WAXS) and indentation hardness have been used to study the development of crystallinity at room temperature of biodegradable poly(hydroxybutyrate) (PHB) and its copolymer with hydroxyvalerate (PHB/HV) containing 12% of valerate. Measurements were carried out immediately after quenching the samples from the molten state (200 ºC) in ice water and over two weeks of storage at room temperature. WAXS showed that the crystallization of the PHB-based polymers initiated within the first minutes of storage at room temperature, the copolymer displaying a higher rate of crystallization than the homopolymer. For all samples, the degree of crystallinity,α, nearly reached a plateau value within the first hour of crystallization. Concurrently to the development of crystallinity, microhardness values,H, clearly rose as crystallization occurred. Monitoring the crystallization for over two weeks showed that after the rapid increase ofαandH, there was a slow monotonic growth of these properties. A correlation between nanostructure and microhardness is found at all stages of the crystallization process.
Computational Studies of the NiTi Alloy System: Bulk, Supercell, and Surface Calculations
Authors: Stott Amanda C. , Abel Phillip B. , DellaCorte Christopher , Pepper Stephen V. , Dixon David A. 
Published: April 2011

ABSTRACTPlane wave ab initio density functional theory (DFT) calculations of the B2 NiTi (100), (110), and (111) surfaces, the B2 and B19´ phases of NiTi, and the supercell structures of NiTi, Ni4Ti3 and Ni3Ti are reported. Electronic energies from the electronic structure calculations are used to assess relative stability of the different surface and supercell geometries.
Evaluation of Crack Growth Retardation Effect Due to Nano-scale Voids Based on Molecular Dynamics Method
Authors: Taniguchi Shin , Kameda Toshihiro 
Published: April 2011

ABSTRACTThis study has investigated the crack growth retardation effect due to plural nano-scale voids in Cu single crystals using a molecular dynamics (MD) method. Focusing on an interaction between nano-scale voids and dislocations, we have evaluated the optimum placement for crack growth retardation. MD simulations showed that the dislocation activity was further enhanced due to plural nano-scale voids continuously placed on the primary slip direction. The significant ductility enhancement and slight yield stress increase due to the crack shielding effect of nano-scale voids were observed.
In Situ Spectroscopy and Modeling of Deformation Behavior of Nanoscale Interfacial Materials
Authors: Suzuki Takakazu , Suetaka W. , Suzuki A. , Sato T. , Suzuki T. 
Published: April 2011

ABSTRACTIn this work, the behavior of molecules in thin-film lubricants, several tens of nanometers thick, is studied by in situ reflection infrared spectroscopy and by molecular dynamics simulations. The effect of fatty acid additives on the properties of these interfacial films is also studied. The results of these experiments are presented and interpreted, and the latest outcomes of molecular dynamics simulations are discussed. It is concluded that the molecular orientation in thin films of interfacial materials is markedly affected by the use of additives.