bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single-step Photo fabrication of Kinoforms in use of Azobenzene-containing Polymer Films
Authors: Yasuda Shin , Minabe Jiro , Kawano Katsunori , Maruyama Tatsuya , Yamada Hidenori 
Published: April 2011

ABSTRACTWe propose a new method of optically fabricating kinoforms using polyester containing cyanoazobenzene units in the side chain. This method utilizes the surface relief structures induced optically on the azopolymer films. Using a gray-tone amplitude mask with black and white lines as a spatial light modulator, we constructed the surface relief structures on the azopolymer films with an argon-ion laser beam (488nm). The relief depths constructed were deep enough to provide a wide range of visible light with a phase difference of 2π. In addition, irradiation on the azopolymer film with a spatially modulated light that had multilevel intensities inscribed the multilevel relief structure reflecting the intensity modulation. This property is applicable to the fabrication of diffractive optical elements, especially kinoforms, because the multilevel relief structure provides an incident light with phase modulation. We designed a phase pattern for a kinoform by computation and expressed it as a gray-tone amplitude mask. Irradiation on the film through the gray-tone mask with the pump beam inscribed a multilevel relief structure that diffracted an incident light to produce a desired image. The desired image appeared without the effect of the internal refractive index modulation of the film. We, therefore, confirmed a possibility of fabricating a kinoform with a multilevel relief structure on the azopolymer film. Since our fabrication method for kinoforms requires only exposure, it has a significant advantage over other techniques that require additional processes such as developing and etching.
The Effect of Interfacial Chemistry on Metal Ion Penetration into Polymeric Films
Authors: Mallikarjunan Anupama , Juneja Jasbir , Yang Guangrong , Murarka Shyam P. , Lu Toh-Ming 
Published: April 2011

ABSTRACTIn order to boost the performance of next-generation silicon integrated circuits, polymers with lower dielectric constant compared to silicon dioxide are required as interlayer dielectrics (ILDs). Ion penetration from surrounding interconnect metal (typically copper or aluminum) or from barrier materials (e.g., tantalum or tantalum nitride) under thermal and electrical stresses can lead to premature failure of the polymers. Hence, ion penetration was studied in hybrid organosiloxane polymer (HOSP) using bias-temperature stressing. Metal/polymer interface chemistry, particularly the presence of interfacial oxygen, was found to play a key role in aiding metal ionization, and subsequent mobile ion penetration into dielectrics.
Correlation of Substituent Parameter Values to Electronic Properties of Molecules
Authors: Carroll Natalie , Matsunaga Nikita , Sohlberg Karl 
Published: April 2011

ABSTRACTThere are a vast number of organic compounds that could be considered for use in molecular electronics. Because of this, the need for efficient and economical screening tools has emerged. We have demonstrated that the substituent parameter values (σ), commonly found in advanced organic chemistry textbooks, correlate very strongly with features of the charge migration process. This result supports the use of the σ values as a low cost time saving tool in the selection of compounds for use in molecular electronic devices.
First Applications of Electron Energy-Loss Spectroscopy with High Energy Resolution
Authors: Kothleitner Gerald , Mitterbauer Christoph , Grogger Werner , Zandbergen Henny , Tiemeijer Peter , Freitag Bert , Barfels Melanie , Hofer Ferdinand 
Published: April 2011

ABSTRACTA new transmission electron microscope equipped with a monochromator and a high resolution energy-filter was used for the first time to fully exploit the chemical bonding information contained in the near edge fine structures (ELNES) of electron energy-loss spectra. The instrument is capable of acquiring spectra with an energy resolution in the range of 0.1 eV, thus opening up the way for improved ELNES information. ELNES spectra of TiO2 and CoO have been recorded and are compared with data obtained with a conventional microscope and with x-ray absorption spectroscopy. In case of the L2,3 edges of the transition metals the new instrument revealed previously unobservable fine structure details, but for the O K edges the improved energy resolution does not result in more detailed structural features than observable in common microscopes. Furthermore, the potential of the new microscope to obtain chemical bonding information at the nanometer scale is discussed.
Mechanical properties of stratum corneum studied by nano-indentation
Authors: Yuan Yonghui , Verma Ritu 
Published: April 2011

ABSTRACTStratum corneum acts as a barrier to protect our body, as well as a pathway for conducting skin sensations. Understanding the mechanical properties such as elasticity, yield stress, of stratum corneum is important to improve and develop new products in the personal care industry. In this work, structural properties of stratum corneum are studied by atomic force microscopy (AFM) imaging to reveal surface structure of stratum corneum. To study mechanical properties, AFM force measurements and nano-indentation techniques were used to characterize elastic properties of dry and wet stratum corneum. Nano-DMA measurements were also conducted to characterize visco-elastic properties of the same material.
Magnetic Domain Structures in CoNiFe Thin Films and Lines
Authors: Pérez Lucas , Abril Oscar de , Aroca Claudio , Sánchez Pedro , López Eloísa , Sánchez-Trujillo M.C. 
Published: April 2011

ABSTRACTThin films and arrays of lines of magnetic CoNiFe alloy have been produced by electrodeposition. A magnetic field was applied during the electrodeposition process in order to induce a magnetic anisotropy in the sample. The dependence of the magnetic properties and the magnetic domain structures on the thickness of the films is reported. In addition to this, the magnetic properties and the domain structure of a thin film and an array of lines, with the same thickness and deposited in the same conditions, have been compared. An increase in the coercivity of the array of lines has been shown.
Magnetic Force Microscopy Imaging of Current Paths
Authors: Yongsunthon R. , Stanishevsky A. , Rous P. J. , Williams E. D. 
Published: April 2011

ABSTRACTWe demonstrate Magnetic Force Microscopy (MFM) imaging, at room temperature in air, of a 0.25mA DC current path in a 140nm-wide gold nanowire. The nanowire was created by focused ion beam milling of a 12μm wide Cr/Au line of 20nm/110nm Cr/Au thickness. Iterative fitting of the MFM data to an idealized model of the structure yielded a nanowire resistivity a factor of 3.5 higher than that of a control Cr/Au region which was unaffected by the ion beam processing. MFM imaging of an ion-implant patterned line shows current deflection around the implant region.
Dislocation-mediated Mechanisms of Mass Transport around Nanoindentations in Fcc Metals
Authors: Fuente Oscar Rodríguez de la , Carrasco Esther , González Miguel A. , Rojo Juan M. 
Published: April 2011

ABSTRACTWe present evidence for the operation on reconstructed Au(001) of a novel mechanism, involving dislocation motion, which is much more efficient than surface diffusion to redistribute mass around nanoindentations. Cross-slip of individual dislocations generated around the indentation point, with a screw component perpendicular to the surface, is shown to be responsible for the generation of multiple-storied, crystallographically-oriented terraces around the nanoindentation points. We also show that standard dislocation theory can be used to quantitatively describe the characteristics of the dislocations involved in the different processes around the nanoindentation.
Local Dynamics of Poly(ethylene oxide) Confined in 1nm Slits
Authors: Kuppa V. , Manias E. 
Published: April 2011

ABSTRACTMolecular Dynamics simulations are used to explore the short-time dynamics of nanoscopically confined poly(ethylene oxide). Both bulk and confined systems have been studied using an atomistically detailed force field so as to comparatively illustrate their differences and complement experimental results. Our aim is to elucidate the origins of the counter intuitive distribution of relaxation times for C-H bond reorientation for PEO in severe confinements, as experimentally observed in solid state 2H NMR studies. In contrast with the respective bulk PEO system, where a transition from distinct solid to liquid like dynamics is seen with increasing temperature, for the confined chains there is a coexistence of fast and slow segmental dynamics over a wide temperature range. Our studies have revealed that factors such as local density inhomogeneities, proximity of Li+, and translational motion, synergistically contribute to the generation of fast PEO segmental dynamics in 1nm confinements.
The Element Depth Profiles in Ultrathin Silicon Oxynitride Films
Authors: Asanov Igor P. , Choi Jinhak , Chung Youngsu , Choi Jaemin , Lee Jaecheol 
Published: April 2011

ABSTRACTDistribution of nitrogen in the thin silicon oxynitride films (less than 5 nm) obtained by plasma nitridation of SiO2 has been studied by non-destructive angular dependent XPS. For obtaining information about the element distribution in-depth the regularization technique has been applied. It is shown that the depth of nitrogen penetration increases with decreasing the SiO2 film thickness. In this case the maximum of the nitrogen distribution is enhanced and shifted to the Si-SiO2 interface. The results are compared with depth-profiling obtained by sputtering and wet chemical etching. The dependence of the binding energies on the film thickness has been studied. The influence of different factors on the chemical shift in the ultrathin films has been analyzed.
Advanced 13C Nuclear Magnetic Resonance Investigation of Metal-Ligand Interactions in Monolayer-Protected Gold Nanoparticles: NMR Shifts and Relaxations
Authors: Zelakiewicz Brian S. , Tong YuYe 
Published: April 2011

ABSTRACTWhile self-assembled monolayer (SAM) systems have been intensively investigated since the seminal work of Nuzzo and others in the later 1980s, the detailed nature of the interactions between thiol and gold in terms of surface bonding and ligand motion, a central theme crucial for any further advancements in the field of SAMs, is still elusive and subject to controversy. Nuclear magnetic resonance (NMR) spectroscopy, a canonical technique of chemistry and physics, has the unique ability of providing insightful chemical bonding and ligand motional information. Recent advances in wet chemistry in terms of synthesizing alkanethiol-protected, very stable and almost monodispersed, gold nanoparticles, due to Schriffin and co-workers, enable this feature of NMR to be harnessed in the study of thiol-metal bonding and ligand motions on gold surfaces. Here, we report a detailed 13C NMR shift and relaxation investigation of monolayer-protected gold nanoparticles as a function of metal particle size, by using selectively 13C1-labelled octanethiol. Several interesting results are obtained for the first time: as the gold particle size increases from ca. 1.5 to 4.0 nm, the 13C1 NMR shift moves down-field from ca. 39 to 50 ppm (with respect to TMS), the spin-lattice relaxation rate 1/T1 decreases, and the spin-spin relaxation rate 1/T2 increases. For a given particle size, the 1/T2 varies across the heterogeneously broadened line shape, being higher at the lower field, while there is no clear trend shown in 1/T1. All these results suggest that while particle tumbling may be the dominant spin-lattice relaxation mechanism, the physical properties of the metal core, i.e., more metallic vs. less metallic, are most probably the dominant factors influencing the 13C1 NMR shift and spin-spin relaxation. Now new doors are opened up for more detailed NMR investigations of metal-ligand interactions in SAM systems.
Structural and Elemental Characterization of Fe/Co Nanoparticles Produced through Organometallic Synthesis
Authors: Fejes P. L. , Dumestre F. , Amiens C. , Renaud P. , Chaudret B. , Zurcher P. 
Published: April 2011

ABSTRACTWe report on the structure of and elemental distributions within various magnetic nano-particles synthesized using organometallic precursors. The characterization was carried out using high-resolution transmission electron microscopy (HRTEM), and electron energy loss spectroscopy (EELS), with spectral imaging to investigate elemental distributions within the particles. The crystallinity and oxidation of Fe, Co and Fe-Co particles are discussed. We observe heavy oxidation of Fe particles, while Co particles show, at most, only a thin surface layer of oxide. When Fe and Co are combined to form Fe-Co particles, they are seen to be inhomogeneous, consisting of an Fe core, surrounded by a Co-rich shell.
Tensile Deformation and Fatigue Crack Growth in Bulk Nanocrystalline Al-7.5Mg
Authors: Pao P.S. , Jones H.N. , Gill S.J. , Feng C. R. 
Published: April 2011

ABSTRACTThe fatigue crack growth kinetics and tensile deformation of bulk nanocrystalline Al-7.5Mg were investigated. Nanocrystalline particulates were first prepared by mechanically ball milling spray atomized Al-7.5Mg powders in liquid nitrogen. These particulates were then degassed, consolidated by hot isostatic pressing, and extruded into rods. Bulk nanocrystalline Al-7.5Mg has significantly higher fatigue crack growth rates and lower fatigue crack growth thresholds than those of ingot-processed 7050-T7451. The fatigue crack growth thresholds exhibit only a weak stress ratio dependency and can be identified as having a Class I behavior when using the fatigue classification proposed by Vasudevan and Sadananda. In 3.5% NaCl solution, fatigue crack growth rates of bulk nanocrystalline Al-7.5Mg are as much as three times higher than those obtained in air. Tensile fracture of bulk nanocrystalline Al-7.5Mg is preceded by the formation of a localized shear band. In contrast to the low dislocation density in the as-extruded material, the gage section and the shear band region both exhibited a high dislocation density and dislocation cell structure.
Bimodal Microstructure and Mechanical Properties of Cryomilled Nanocrystalline Al-7.5Mg
Authors: Lee Zonghoon , Witkin David B. , Lavernia Enrique J. , Nutt Steven R. 
Published: April 2011

ABSTRACTThe microstructure and mechanical properties consisting of tensile behavior and hardness of bulk nanocrystalline Al-7.5Mg alloy were investigated. Grain refinement was achieved by cryomilling of atomized Al-7.5Mg powders, and then nanocrystalline powders blended with 15% and 30% coarse-grained Al-7.5Mg powders were consolidated by hot isostatic pressing (HIP) followed by extrusion to produce bulk nanocrystalline Al-7.5Mg alloys. Bimodal structures, which enhance ductility and toughness of nanocrystalline metals, were produced that consisted of nanocrystalline grains and elongated coarse-grain bands. Examination of indentation revealed unusual deformation mechanisms and interactions between the coarse-grain bands and nanocrystalline regions. The ductile coarse-grain bands underwent extensive plastic deformation near indentation, while nanocrystalline regions exhibited limited deformation.
Hybrid nylon-6/silica nanocomposites with improved mechanical properties
Authors: García Monserrat , van Zyl Werner E. , Verweij Henk 
Published: April 2011

ABSTRACTThe study involves the development of new strategies to form technically interesting hybrid nanocomposites with improved mechanical properties. In particular, a new ‘dissolution’ preparative route was developed which incorporates silica nanoparticles (<30 nm) into a nylon-6 matrix. The procedure relies on the judicious choice of organic solvent and pH control. The synthesis involves the dissolution of nylon-6 in formic acid followed by silica particle addition (as an acidified, monodisperse sol) with stirring. Viscous solutions were prepared under cleanroom conditions and casted as thin films which are dried and vacuum treated at ∼60°C. TEM images revealed that the silica particles i.) retained their original shape and size (10–30 nm), ii.) are mono-dispersed and iii.) mainly non-agglomerated. The degree of crystallinity of the composites was determined with XRD as a function of percentage filler added. The nylon-6 phase is semi-crystalline while the silica phase is amorphous. Initial mechanical tests on the composites were conducted and showed with 1wt% silica addition, the E modulus was increased to ∼2600 MPa. The increase in mechanical properties may be a result of the nanosize filler particles which has good synergy with the nylon matrix. Friction and wear properties were also investigated on a pin on disk tribometer by running a flat pin of steel against the composite disc.
Synthesis of Novel Vanadium Oxide Nanotubes and Nanofibers
Authors: Lutta Samuel T. , Dong Hong , Zavalij Peter Y. , Stanley Whittingham M. 
Published: April 2011

ABSTRACTWe are exploring the synthesis and properties of structured vanadium oxides mainly nanotubes and nanorods. Nanotubes initially formed with surfactant templates have been readily exchanged with simple cations without change of the basal-plane structure. These compounds contain d-like vanadium oxide layers with the vanadium in VO6 octahedra. This structure is particularly suitable for redox reactions. In this paper we report on synthesis of vanadium oxide, (NH4)xV2O5-d·nH2O rods using organic polymer as template. This compound has been synthesized by sol-gel reaction and subsequent hydrothermal treatment. TGA, SEM, XRD and FTIR were used to characterize this compound. Thermal analysis of this compound shows that the fibrous morphology is maintained when it is heated in nitrogen and oxygen above 300 °C. However, in both cases the size of the fibers decreases. Performance of this compound as cathode material in secondary electrolyte has been investigated using LiPF6 as electrolyte. A capacity of 140 mAh/g was obtained which remained fairly constant with up to at least 10 cycles. We also investigated electrochemical behavior of thermal products.
An Approach to Nanoglasses through Anodic Oxidation of Sputtered Aluminum on Glass Surface
Authors: Inoue Satoru , Chu Song-Zhu , Wada Kenji 
Published: April 2011

ABSTRACTThe new processes for the preparation of nanoglasses have been developed through anodic oxidation. The aluminum thin film sputtered on the ITO thin film on the glass surface was decomposed into alumina by anodic oxidation technique. The alumina layer possessed nanometer size pore array standing on the glass surface. The sizes of the pore was widened by acid etching from 10∼20nm to a few hundred nm. The glass substrate having the alumina nanostructures on the surface could transmit the UV and visible light at the wavelength range of 200 ∼ 800nm. The TiO2 sol was impregnated into the pores of alumina layer and the sample was heated at ∼ 400 °C for 2 hr, converted into TiO2 nanotubes of anatase phase. The acid etching could remove the alumina skeletons, leaving the TiO2 nanotube array on the glass surface. These glasses were transparent to the light in UV-visible region. The electro deposition technique was applied to the introduction of Ni metal into pores, giving Ni nanorod array on the glass surface. The glass samples possessing TiO2 nanotube array showed very good catalytic function on the decomposition of acetaldehyde gas under the irradiation of UV light. The effect of the dimensions of the Ni nanorods on the magnetization was investigated.
Microstructures and Mechanical Properties of Nanostructured Copper-304 Stainless Steel Multilayers Synthesized by Magnetron Sputtering
Authors: Zhang X. , Misra A. , Wang H. , Kung H. , Embury J. D. , Hoagland R. G. , Nastasi M. 
Published: April 2011

ABSTRACTNanostructured Cu/304 stainless steel (SS) multilayers were prepared by magnetron sputtering at room temperature. 304SS has a face-centered cubic (fcc) structure in bulk. However, in the Cu/304SS multilayers, the SS layers exhibited fcc structure for layer thickness of less than or equal to 5 nm. For 304SS layer thickness larger than 5nm, bcc 304SS grains were observed to grow on top of the initial ≈ 5 nm of fcc SS. The maximum hardness of Cu/304SS multilayers was ≈ 5.5 GPa (factor of two enhancement compared to rule of mixtures hardness) achieved at a layer thickness of 5nm, with a decrease in hardness with decreasing layer thickness below 5 nm. The hardness of fcc/fcc Cu/304SS multilayers (layer thickness ≤ 5 nm) is compared with Cu/Ni, another fcc/fcc system, to gain insight on how the mismatch in physical properties such as lattice parameters and shear moduli of the constituent layers affect the peak hardness achieved in these nanoscale systems.
Characterization of Mechanical Deformation of Nanoscale Volumes
Authors: Perrey Christopher R. , Mook William M. , Barry Carter C. , Gerberich William W. 
Published: April 2011

ABSTRACTThe mechanical properties of nanoscale volumes and their associated defect structure are key to many future applications in nanoengineered products. In this study, techniques of mechanical testing and microscopy have been applied to better understand the mechanical behavior of nanoscale volumes. Nanoindentation has been used to investigate important mechanical material parameters such as the elastic modulus and hardness for single nanoparticles. New sample preparation methods must be developed to allow the necessary TEM characterization of the inherent and induced defect structure of these nanoparticles. Issues of chemical homogeneity, crystallinity, and defect characteristics at the nanoscale are being addressed in this study. This integration of investigative methods will lead to a greater understanding of the mechanical behavior of nanostructured materials and insights into the nature of defects in materials at the nanoscale.
Interface Conduction between Conductive ReO3 Thin Film and NdBa2Cu3O6 Thin Film
Authors: Ohkubo Manabu , Fukai Kumiko , Matsuo Kohji , Iwata Nobuyuki , Yamamoto Hiroshi 
Published: April 2011

ABSTRACTThe Re oxide films were deposited on quartz glasses by RF reactive sputtering from a Re metal target. The lowest resistivity was observed in the film in-situ annealed at 200°C in Ar atmosphere and showed the order of 10-4 Ω cm of which the value was still about 10 times as large as that of a single crystal ReO3. The temperature dependence of the resistivity revealed a metallic behavior. A superconductivity did not take place in the bilayered film of ReO3 / NdBa2Cu3O6. In the interface region the resistivity minimum probably caused by the Kondo effect was observed in the neighborhood of 120K.
The Growth of Bamboo-Structured Carbon Tubes Using a Copper Catalyst
Authors: Farmer B.L. , Holmes D.M. , Vandeperre L.J. , Stearn R.J. , Clegg W.J. 
Published: April 2011

ABSTRACTCatalytic decomposition of methane has been used to grow bamboo-structured carbon tubes at temperatures ranging from 1233 K to 1291 K. No tube growth was observed at temperatures less than 1233 K, whilst above 1291 K pyrocarbon was the dominant product. It is shown that the average size of the copper catalyst particles was influenced by the reaction temperature, with the reciprocal of the maximum size of the copper particle decreasing linearly with temperature. This is consistent with the idea that the melting point can be reduced by surface energy effects. Observations show that under the conditions here the catalyst particle penetrates into the carbon fibre and a mechanism is proposed for development of the bamboo structure based upon the energy changes that take place.