bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical Properties of Polyethylene Containing Defunctionalized Single Wall Carbon Nanotubes
Authors: Shofner Meisha L. , Peng Haiqing , Gu Zhenning , Khabashesku Valery N. , Margrave John L. , Barrera Enrique V. 
Published: April 2011

ABSTRACTTo take advantage of the benefits of chemical functionalization and the desirable properties of unfunctionalized SWNTs, this research studies the effect of removing functional groups from SWNTs dispersed in a polymer matrix. Chemical functionalization of single wall carbon nanotubes (SWNTs) is a method for disrupting rope structure and adding reactive species to the nanotube to improve interfacial bonding and load transfer in composites, but changes to the nanotube hexagon structure caused by chemical modifications are expected to have a detrimental effect on the SWNTs' intrinsic mechanical properties. Thus, composites containing defunctionalized SWNTs and polyethylene are analyzed to evaluate the effect of functional group removal on the mechanical properties. The mechanical properties are measured using tensile tests. Issues of defects in the SWNT structure, polymer degradation, and changes in the fiber/matrix bonding as a result of functionalization removal are studied using Raman spectroscopy, thermogravimetric analysis, infrared spectroscopy, and dynamic mechanical analysis.
Synthesis and mechanical characterisation of Fe-based bulk metallic glasses and mixed amorphous/crystalline phases
Authors: Castellero Alberto , Lindsay Greer A. , Reza Yavari A. , Inoue Akihisa 
Published: April 2011

ABSTRACTFully amorphous and mixed amorphous/crystalline bulky (Fe77+yGa3P9.5-yC4.5B3.5Si2.5)(100-x)/100Fex alloys were prepared varying Fe and Fe-P contents. The effect of the compositional changes on glass forming ability (GFA), stability of the amorphous phase and mechanical properties was studied. When y = 0 and x is enhanced from 0 to 2, the stability of the supercooled liquid region decreases of 10 K. For x = 0 and y = 3.5 the glass forming ability is drastically reduced leading to a mixed structure consisting of bcc-Fe, Fe3(P,C,B) and a small fraction of amorphous phase.During compression test at room temperature the deformation of fully amorphous samples (y = 0) is dominated by the initiation and propagation of shear bands with consequent nil or small plastic deformation (0.2 % at 3000 MPa) for the alloys with x = 2 and x = 0 respectively. Embrittlement of (Fe77Ga3P9.5C4.5B3.5Si2.5)0.98Fe2 was observed after partial and full devitrification.A higher Young modulus and a maximum strength of 3300 MPa were shown by the as cast partially crystalline Fe80.5Ga3P6C4.5B3.5Si2.5 alloy; also in this case, no yielding was detected.Finally, compression tests at high temperature for fully amorphous Fe77Ga3P9.5C4.5B3.5Si2.5 showed inhomogeneous deformation up to 402°C. Homogeneous non-Newtonian plastic deformation was detected at 427°C. Newtonian homogeneous flow at 452°C is limited by the crystallisation of the superliquid and consequent final failure.
On the Wear Assessment of Multilayer Nanocrystalline Diamond Coated Implants of the Temporomandibular Joint
Authors: Papo Malesela J. , Catledge Shane A. , Machado Camilo , Kashef Somaieh , Eberhardt Alan E. , Vohra Yogesh K. 
Published: April 2011

ABSTRACTWe deposited multilayer Nanocrystalline Diamond (NCD) thin films on Ti-6Al-4V substrates that were machined to imitate the shapes of the condyle and fossa of the temporomandibular joint (TMJ). We performed low stress wear assessment experiments on condyle/fossa pairs mounted in a custom-built mandibular movement simulator (MMS) for 5 x 105 loaded cycles at 1.2 Hz, which is equivalent to 4.4 years of clinical use. Analysis of wear surfaces on the control and the NCD-coated pairs indicated that no film delamination occurred on the NCD-coated condyle/fossa couple and that wear damage was extensive on the uncoated condyle/fossa pair. The high stress wear tests performed using the Ortho-POD machine at loads of 80 and 165 N showed that loss of film on the condyle specimens occurred after 3300 and 341 cycles, respectively. A subsequent evaluation of the influence of condyle curvature on wear by articulating a multilayer condyle/disk pair at a load of 50 N and 250 000 cycles at 1.2 Hz, showed that film delamination on the condyle occurred after 12500 cycles and no loss of film was observed on the disk after 250 000 cycles of articulation. Our results show that the observed lower film lifetimes on the condyles at high stresses are not related to intrinsic stresses in the film but probably due to lower film adhesion on the curved surfaces of the condyle.
Space Environment Effect on Fluorinated Polymers
Authors: Chipara M. , Edwards D. L. , Zaleski J. , Hoang B. , Przewoski B. , Balascuta S. 
Published: April 2011

ABSTRACTThe effects of the space environment on polytetrafluorethylene and some fluorinated polymers, copolymers, and blends are critically reviewed. It is shown that in low altitude orbits such as Low Earth Orbit and Geostationary Orbit the presence of both ionizing radiation and atomic oxygen triggers a synergetic degradation of materials based on fluorinated polymers. The behavior is due to the lability of the in-chain alkyl radical to oxygen attack. It is concluded that fluorinated polymers should not be used as materials for space applications, as long as the mission implies low Earth orbits.
Coupling between order parameter and compositional fluctuations in the irradiation induced monoclinic to tetragonal phase transition in pure zirconia.
Authors: Simeone D , Baldinozzi G , Gosset D. , Dutheil M. 
Published: April 2011

ABSTRACTZirconia, oxidation product of Zircaloy cladding elements of nuclear plants, exhibits an unusual behaviour under irradiation. Impinging ions and neutrons induce a monoclinic to tetragonal phase transition at room temperature in this solid. To understand this modification of the positions of the stability lines in such a solid under irradiation, we have studied the monoclinic to tetragonal first order phase transition versus temperature in pure micrometric and nanometric zirconia samples. From these works, it was possible to understand the behaviour of this material under irradiation pointing out the key role of defects induced irradiation on its phase diagram.
NMR study of proton beam irradiated TlH2PO4
Authors: Kim Se Hun , Lee Kyu Won , Jang Jae Won , Lee Cheol Eui 
Published: April 2011

ABSTRACTWe have investigated proton beam irradiation effects on TlH2PO4 (TDP) showing an antiferroelectric phase transition and a ferroelastic phase transition. The sample was irradiated by 1 MeV proton beams to a dose of 1015 ions/cm2 and studied by means of 1H NMR measurements. The NMR rotating-frame spin-lattice relaxation time was measured as a function of temperature, and analyzed in order to understand the proton motions and the order parameter reflecting the structural changes caused by the proton irradiation.
Irradiation Effect of Nitrogen Ion Beam on Carbon Nitride Thin Films
Authors: Aizawa Shinichiro , Nasu Yuka , Aono Masami , Kitazawa Nobuaki , Watanabe Yoshihisa 
Published: April 2011

ABSTRACTIrradiation effect of low-energy nitrogen ion beam on amorphous carbon nitride (a-CNx) thin films has been investigated. The a-CNx films were prepared on silicon single crystal substrates by hot carbon-filament chemical vapor deposition (HFCVD). After deposition, the CNx films were irradiated by a nitrogen ion beam with energy from 0.1 to 2.0 keV. Irradiation effect on the film microstructure and composition was studied by SEM and XPS, focusing on the effect of nitrogen ion beam energy. Surface and cross sectional observations by SEM reveal that the as-deposited films show a densely distributed columnar structure and the films change to be a sparsely distributed cone-like structure after irradiation. It is also found that 2.0 keV ions skeltonize the films more clearly than 0.1 kev ions. Depth profiles of nitrogen in the films observed by XPS show that nitrogen absorption into films is more prominent after irradiation by 0.1 keV nitrogen ions than 2.0 keV ions.
Destruction of Multiwall Carbon Nanotubes under the Influence of Ion Bombardment
Authors: Brzhezinskaya Mariya M. , Baitinger Eugen M. , Shnitov Vladimir V. 
Published: April 2011

ABSTRACTIn this paper, the results of experiments on irradiation of the multiwall carbon nanotube (MWNT) samples by argon ions with energy of 1 keV are presented. They were obtained by energy loss spectroscopy of reflected electrons and Auger electron spectroscopy.It was found that ion irradiation of MWNTs decreases the characteristic energy and increases the full width at the half of the maximum (FWHM) of the π-plasmon peak. The plasmon relaxation time was found.
Nanostructural Fluctuation in Radiation-Amorphized Alloys
Authors: Watanabe Seiichi , Takahashi Heishichirou , Lam Nghi Q. 
Published: April 2011

ABSTRACTSpatio-temporal nanostructural fluctuations brought about by transient, metastable atom-cluster formation and the manifold nature of inherent atomic ordering in electron-irradiation-amorphized NiTi were investigated by using a combination of in situ observations inside a high-resolution high-voltage electron microscope (HR-HVEM) and image analyses of molecular-dynamics-simulated atom configurations. Nanometer-sized clusters were found to appear and disappear in the irradiated region. The random formation and annihilation of such nanoclusters are believed to be responsible for nanostructural fluctuations which appear to be related to transitions among manifold inherent structural states, involving multirelaxation processes. Temporal fluctuations in the amorphized structure were manifested through the dose-dependent local amorphization parameter, potential energy, volume, and inherent cluster bonding. The observed fluctuations obey a universal power law. Within the framework of the multi-Lorentzian picture, the resultant power law describes the distribution of multirelaxation times or cluster lifetimes. In addition, a unified relation for the temporal autocorrelation function for such fluctuation phenomena has been determined.
Silicon Micro-Photonic Structure for Ultra-Sensitive Biosensing
Authors: Schmidt Bradley , Almeida Vilson , Manolatou Christina , Preble Stefan , Lipson Michal 
Published: April 2011

ABSTRACTWe demonstrate a micron-size planar silicon photonic device that is able to detect low concentrations of metal nano-particles approaching single particle detection. This sensitivity is achieved by using strong light confining structures that enhance the extinction cross-section of metal nano-particles by orders of magnitude. Structures were fabricated and measurements of the transmission spectra of the devices demonstrate the detection of 10 nm diameter gold particles resting on the device with a density of fewer than 2 particles per 104 nm2 (the area of the sensing region surface). Using such a device, in a fluidic platform, one could detect the presence of a single metal nano-particle specifically bound to various analytes, enabling ultrasensitive detection of analytes including DNA, RNA, proteins, and antigens.
Three-Dimensional Lithography for Rutile TiO2 Single Crystals using Swift Heavy Ions
Authors: Awazu Koichi , Fujimaki Makoto , Ohki Yoshimichi , Komatsubara Tetsuro 
Published: April 2011

ABSTRACTWe have developed a nano-micro structure fabrication method in rutile TiO2 single crystal by use of swift heavy-ion irradiation. The area where ions heavier than Cl ion accelerated with MeV-order high energy were irradiated was well etched by hydrofluoric acid, by comparison etching was not observed in the pristine TiO2 single crystal. Noticed that the irradiated area could be etched to a depth at which the electronic stopping power of the ion decayed to a value of 6.2keV/nm. We also found that the value of the electronic stopping power was increased, eventually decreased against depth in TiO2 single crystal with, e.g. 84.5MeV Ca ion. Using such a beam, inside of TiO2 single crystal was selectively etched with 20% hydrofluoric acid, while the top surface of TiO2 single crystal subjected to irradiation was not etched. Roughness of the new surface created in the single crystal was within 7nm with the atomic forth microscopy measurement.
Very large plasmon band shift in strongly coupled metal nanoparticle chain arrays.
Authors: Sweatlock L. A. , Penninkhof J. J. , Maier S. A. , Polman A. , Atwater H. 
Published: April 2011

ABSTRACT30 MeV silicon ion irradiation of silica glass containing 10 nm silver nanocrystals causes alignment of the nanocrystals in closely spaced linear arrays along the ion tracks. Optical transmission measurements show a 1.5 eV splitting of the surface plasmon resonant absorption bands for polarizations longitudinal and transversal to the arrays. The resulting material is a highly anisotropic glass that absorbs blue light of one polarization, and near-infrared light of the orthogonal polarization. Finite-difference time domain simulations are used to explore the effects of interparticle spacing and total array length on the absorption properties.
Optical Properties of Dielectric and Magnetic Photonic Crystals in the Low-Frequency Limit
Authors: Krokhin Arkady , Arriaga Jesús , Reyes Edgar 
Published: April 2011

ABSTRACTWe consider the long-wavelength limit for two-dimensional photonic crystals - periodic arrangement of magneto-dielectric rods with dielectric and magnetic constant εa and μa embedded in a magneto-dielectric background (εb,βb). Using the Fourier expansion method in the low-frequency limit (ω → 0 ) we develop an effective medium theory and give a rigorous proof that, in this limit, a periodic medium behaves like a homogeneous one. We derive compact analytical formulas for the effective index of refraction of a 2D photonic crystal. These formulas are very general, namely the Bravais lattice, the cross-sectional form of cylinders, their filling fractions and the dielectric and magnetic constants are all arbitrary. For non-magnetic materials, μa = μb = 1, we show how to introduce index ellipsoid and demonstrate that the E-mode is an ordinary wave and the H -mode is an extraordinary wave. For magnetic materials the both modes turn out to be extraordinary. This unusual property is unknown for natural crystals.
Growth and Optical Properties of 2D Photonic Crystals Based on Hexagonal GaAs/AlGaAs Pillar Arrays by Selective-Area Metalorganic Vapor Phase Epitaxy
Authors: Motohisa J. , Takeda J. , Inari M. , Fukui T. 
Published: April 2011

ABSTRACTWe report on the growth of GaAs and GaAs/AlGaAs heterostructured hexagonal pillar arrays using selective area (SA) metalorganic vapor phase epitaxy (MOVPE) for the application of two-dimensional photonic crystals (2D-PhCs). SA-MOVPE was carried out on SiO2 masked (111)B GaAs substrates with circular or hexagonal hole openings. Extremely uniform array of hexagonal GaAs/AlGaAs pillars consisting {110} vertical facets with their diameter of order of 200 nm were obtained. Unexpectingly strong intense light emission was observed for the room temperature photoluminescence measurement, which suggests low surface nonradiative recombination and enhancement of the light extraction efficiency of the pillar arrays.
Dispersion Properties of Photonic Crystal Fibers - Issues and Opportunities
Authors: Lægsgaard J. , Barkou Libori S. E. , Hougaard K. , Riishede J. , Larsen T. T. , Sørensen T. , Hansen T. P. , Hansen K. P. , Nielsen M. D. , Jensen J. B. , Bjarklev A. 
Published: April 2011

ABSTRACTThe dispersion, which expresses the variation with wavelength of the guided-mode group velocity, is one of the most important properties of optical fibers. Photonic crystal fibers (PCFs) offer much larger flexibility than conventional fibers with respect to tailoring of the dispersion curve. This is partly due to the large refractive-index contrast available in silica/air microstructures, and partly due to the possibility of making complex refractive-index structures over the fiber cross section. We discuss the fundamental physical mechanisms determining the dispersion properties of PCFs guiding by either total internal reflection or photonic bandgap effects, and use these insights to outline design principles and generic behaviours of various types of PCFs. A number of examples from recent modeling and experimental work serve to illustrate our general conclusions.
Imaging, Manipulating, and Analyzing with Nanometer Precision: Application of the Nanoworkbench
Authors: Guise Olivier , Ahner Joachim , Levy Jeremy , Yates John T. 
Published: April 2011

ABSTRACTWe report the development of novel nanometer-scale manipulative and analytical devices for imaging, chemically analyzing and manipulating nanometer-scaled materials. Two different versions of the nanoworkbench are operating currently at the Surface Science Center of the University of Pittsburgh and at the Seagate Research Center in Pittsburgh. The instrument at Seagate consists of a modified commercially available high resolution scanning electron microscope (lateral resolution ∼1 nm at 10 kV) in combination with a set of four unique nano-manipulators, operating in the pressure range from 102 to 10−7 mbar. At the University of Pittsburgh a home-built UHV version of the nanoworkbench is in operation. In this UHV-instrument, several inter-connected UHV chambers allow in-situ deposition of thin-films and conventional surface analysis. The resolution of the SEM of the UHV system is limited to about 50 nm. We report the first results obtained by using both versions of the nanoworkbench, where we succeeded in writing patterns of ultra-small carbon-containing dots (8nm in diameter) with high position accuracy (<5nm) by electron-beam-induced deposition of carbon-containing background gases. Additionally, four-point probe measurements were performed on a SiGe system.
Affinity Rate Law Failure to Describe Sodium Borosilicate Glass Alteration Kinetics
Authors: Frugier P. , Gin S. , Jégou C. 
Published: April 2011

ABSTRACTSimplified glass compositions were chosen to improve our knowledge of the alteration kinetics of complex glasses dedicated to the confinement of high-level waste. Since 1998, the sodium borosilicate glass system is at the center of a passionate debate between an affinity-based kinetic rate law and a protective surface layer theory. All the authors who have investigated ternary 68/14/18 SiO2–B2O3–Na2O glass agree on the fact that the affinity law cannot satisfactorily account for its alteration kinetics. Some authors explained that these discrepancies between classical kinetic rate law and experimental findings could be due to macromolecular amorphous separation in the 68/14/18 sodium borosilicate system and that this simplified glass could be divided into 90% reedmergnerite (NaBSi3O8) and 10% diborate (Na2O–2B2O3). This article provides evidence of the homogeneity of ternary 68/18/14 SiO2–B2O3–Na2O glass at nanometric scale and shows that even phase separation at less than nanometric scale could not explain the inability of hydrated glass-solution affinity laws to describe its alteration. The relative simplicity of the SiO2–B2O3–Na2O chemical system allows a critical examination of the macroscopic alteration laws developed over the last twenty years based only on the hydrated glass-solution chemical affinity without taking into account the formation and reactivity of the gel or its passivating properties.
Interactions of Simulated High Level Waste (HLW) Calcine with Alkali Borosilicate Glass
Authors: Morgan S. , Hand R. J. , Hyatt N. C. , Lee W. E. 
Published: April 2011

ABSTRACTThis study looks at the interactions between simulated calcined high level waste from fuel reprocessing and mixed alkali borosilicate glass frit in the early stages of melting, and the possibility of the formation of yellow phase during these stages. Simulant “calcine” from a full scale inactive trial (Magnox: oxide “blend” 25:75) was pre-mixed with alkali borosilicate glass, to achieve a 25wt% waste loading, and melted at 1050°C at various times. It is shown that dissolution occurs in two separate stages; the first involves formation of a low density CsLiMoO4 fluid, which separates and forms a yellow/green layer on the surface of the melt, accompanied by some dissolution of rare- earth elements (Nd, Ce, Gd) and Zr from the waste into the glass matrix. The second stage entails more extensive migration of these rare-earth elements into the glass, and the disappearance of the surface layer on the melt. The glass appears more homogenized at the later stages of melting, but still contains undissolved particles of calcine after 16 minutes.
Using Acoustic Emission in Quality Control of Glass and Ceramics for Radioactive Waste Immobilization
Authors: Belov V. Z. , Aloy A. S. , Khlopin V. G. 
Published: April 2011

ABSTRACTLaboratory scale unit for registration of acoustic emission (AE) signals was used for integrity control of glass granules and ceramic bodies. AE waveform recorded in course of the temperature changes has been shown to allow for an unambiguous interpretation and may be used for nondestructive quality control of glass and ceramics bodies.
Fabrication of 239/238Pu-Zirconolite Ceramic Pellets by Natural Sintering
Authors: Advocat T. , Jorion F. , Marcillat T. , Leturcq G. , Deschanels X. , Boubals J. M. , Bojat L. , Nivet P. , Peuget S. 
Published: April 2011

ABSTRACTZirconolite is a potential inorganic matrix that is currently investigated in France, in the framework of the 1991 radioactive waste management law, with a view to provide durable containment of the trivalent and tetravalent minor actinides like neptunium, curium, americium and small quantities of unrecyclable plutonium separated from other nuclear waste. To confirm the actinide loading capacity of the zirconolite calcium site and to study the physical and chemical stability of this type of ceramic when subjected to alpha self-irradiation, zirconolite ceramic pellets were fabricated with 10 wt% plutonium oxide (isotope 239 or 238). The 55 pellets are dense (> 93.3% of the theoretical density on average) and free of cracks. They are characterized by a grain size of between 10 and 20 micrometers. X-ray diffraction analyses confirmed the presence of the zirconolite 2M crystalline structure.
Key Scientific Issues Related to the Evolution of Spent Nuclear Fuel in Long Term Dry Storage and Geological Disposal
Authors: POINSSOT Christophe , FERRY Cécile , GRAS Jean-Marie 
Published: April 2011

ABSTRACTThe anticipated long term evolution of spent nuclear fuel as well as the remaining scientific key issues are presented for the various boundary conditions that can be encountered in long term dry storage and geological disposal. Spent fuel is expected to evolve significantly in closed system conditions which are representative of long term dry storage and the first stages of geological disposal. The mechanical evolution of the grain boundaries, the fate of helium and the evolution of the RN location within the pellet are the three major questions to be addressed which could significantly modify the physical and chemical state of the fuel. In addition, mechanisms and kinetics of fuel alteration by water in deep geological repository are still to be more deeply understood, in particular the inventory of the instant release and the radiolytic dissolution processes, to get a robust and reliable source term.