bluuebunny/crossref_metadata_2025_split huggingface dataset:
The variation in elastic properties of limpet teeth
Authors: Lu Dun , Hang Fei , Barber Asa H. 
Published: November 2012

ABSTRACTLimpet teeth are an example of a biological short fiber reinforced composite material used for a mechanical function. The local micro-scale elastic properties of limpet teeth were examined by bending FIB fabricated beams of the limpet tooth material using atomic force microscopy (AFM). The elastic modulus values for the limpet tooth material varied from 140 GPa at the tooth posterior edge, through 90 GPa at the tooth core to 120 GPa at the tooth anterior edge. This variation in the elastic modulus of limpet tooth material at the posterior, interior and core regions of the tooth is indicative of a mechanically graded structure and is expected to enhance the durability of limpet teeth during rasping over rock surfaces during feeding.
Hierarchical Structure of Porosity in Cortical and Trabecular Bones
Authors: Novitskaya Ekaterina , Hamed Elham , Li Jun , Manilay Zherrina , Jasiuk Iwona , McKittrick Joanna 
Published: November 2012

ABSTRACTIn this paper the amount and morphology of cortical and trabecular bone porosities were estimated using optical microscopy and micro-computed tomography technique. The hierarchical structure of porosity at different structural scales spanning from a single lacuna (sub-microscale) to trabecular or cortical bone levels (mesoscale) was characterized and described. This study was conducted by using samples of untreated, deproteinized and demineralized bones, to obtain better insight into the bone structure and porosities. The motivation of this work is that the porosity in bone has a major effect on its mechanical response, yet it is often neglected in bone models. Investigations of the mechanical properties of bone and its main components (collagen and mineral phases), complemented by modeling, are of importance in orthopedics.
Hydrophobicity of Teflon Coated Well-Ordered Silver Nanorod Arrays
Authors: Alagoz Arif S. , Khudhayer Wisam J. , Karabacak Tansel 
Published: November 2012

ABSTRACTFrom wings of flies to plant leafs, hydrophobic surfaces are well-common in nature. Many of these surfaces have micro and nano hierarchical structures coated with low surface energy layer. In this work, we mimicked similar structure by fabricating Teflon coated periodic and well-ordered silver nanorod arrays and investigated the effect of nanorod separation on water contact angle (WCA). The silver nanorod arrays were deposited on patterned and flat silicon substrates using glancing angle deposition (GLAD) technique. Then a thin layer of Teflon was deposited on the silver nanorods by small angle deposition (SAD) technique. A systematic increase in water contact angle was observed with increasing nanorod separation which is attributed to the decreased area fraction of solid-liquid interface.
Formation and Applications of Hierarchically Porous Carbon, Metals and Metal Oxides Formed by Nanocasting
Authors: Sayler Franchessa M. , Grano Amy J. , Scogin William , Sanders Pasha , Smått Jan-Henrik , Shaughnessy Kevin H. , Bakker Martin G. 
Published: November 2012

ABSTRACTHierarchically porous materials are of interest in a wide range of applications. If the materials are electronic or ionic conductors such materials are of interest as electrodes for use in fuel cells, flow batteries, electrocatalysis, and pseudo/supercapacitors. We have demonstrated the synthesis of hierarchically porous carbon, metal and metal oxide monoliths. Hierarchically porous silica with porosity at three length scales: 0.5-30 micrometer, 200-500 nm, and 3-8 nm, is used as a template to form these materials. The porosity of the silica template is produced by spinodal decomposition (0.5-30 micrometer), particle agglomeration (200-500 nm) and addition of surfactant or block copolymer (3-8 nm). Nanocasting: replication of all or part of the structure via one of a number of chemical replication techniques has been used to produce the carbon, metal oxide and metal replicas. The final surface areas of the materials can be as high as 1200 m2/g for carbon replicas, and >300 m2/g for metals and metal oxides. The use of the nanocasting technique allows for formation of materials that are compositionally or spatially heterogeneous.We report here results on the synthesis and characterization of hierarchically porous monoliths of carbon and, nickel and the use of some of these monoliths in catalysis and electrochemical capacitors.
Light Splitting Function of Branched Chains of Microspheres Fabricated by Self-Assembly Process
Authors: Mitsui Tadashi , Wakayama Yutaka , Onodera Tsunenobu , Hayashi Takeru , Ikeda Naoki , Sugimoto Yoshimasa , Takamasu Tadashi , Oikawa Hidetoshi 
Published: November 2012

ABSTRACTUsing a self-assembly process, we fabricated ordered chains of transparent polystyrene microspheres that have 30°- and 60°-branched structures and that act as coupled-resonator optical waveguides (CROWs). We then observed the optical properties of propagation light through the CROWs. The light spectra were directly measured by guide-collection-mode near-field scanning optical microscopy (NSOM) techniques. The spectrum of light propagating to the 60°-branch shows some sharp peaks, which seem to be associated with whispering gallery modes (WGMs). On the other hand, the spectrum of light propagating to the 30°-branch shows rather broad peaks. Moreover, we observed the detailed structures of the CROWs by high-resolution scanning electron microscopy (HR-SEM), and performed a finite-difference time-domain (FDTD) simulation to explain the NSOM spectra. The results suggest that the microspheres’ branching chains themselves have a light-splitting function, which is a kind of wavelength-selective filter.
Strong Multimode Photonic Microresonator and Nanoparticle Interactions
Authors: Ostrowski M. , Pignalosa P. , Yi Y. 
Published: November 2012

ABSTRACTWe have demonstrated strong multimode photonic microresonator and nanoparticle interactions by using an integrated micro disk resonator from through port of the laser coupling bus waveguide. In addition to the fundamental resonance mode, disk resonator has higher order resonance modes. The excited higher order mode has a node at the position where the electromagnetic energy of the fundamental mode is close to a maximum. Here we report that a self referencing mechanism can be achieved by simultaneous excitation of both fundamental and 2nd order micro disk optical resonance modes. Additionally, we are able to measure the area around the maximum of the fundamental resonance mode and the node of the higher order mode, which have overlaps in the disk. In this work, we used on chip disk microresonator as the example, as a variety of types of optical microresonators have been investigated; we used nanoparticle to interact with the two optical resonance modes excited by the coupling bus waveguide, where the nanoparticle can be either dielectric materials or metallic materials. The strong photonic microresonator and nanoparticle interactions have variety of applications for optical switches, waveguides and detection. The self-referencing characteristics of the two optical resonance modes have potential to achieve photonic functions independent of external perturbation, such as temperature change.
Application of 3-D Hierarchically Porous Silver, Cobalt Oxide and Zinc Oxide Monoliths to Chromatographic Separations
Authors: Sayler Franchessa M. , Grano Amy , Wiedmer Susan , Smått Jan-Henrik , Bakker Martin G. 
Published: November 2012

ABSTRACTHierarchically porous silica monoliths were introduced into liquid phase chromatography at the beginning of the last decade. The high surface area, high void volume and bicontinuous nature of the porosity of the materials are significant advantages over existing chromatographic supports and have resulted in rapid acceptance of these materials into the chromatography market.We report here on the synthesis of 3-D porous silver, cobalt oxide and zinc oxide monoliths, their materials characterization, fabrication as liquid chromatographic columns and initial chromatographic characterization. The, as prepared, columns gave very low back pressure, consistent with the bicontinuous nature of the columns. Cobalt oxide and zinc oxide both demonstrated retention of a number of nitrogen heterocycles, providing the basis for molecular separation.
Low-temperature Phosphorus Doping To Silicon Using Phosphorus-related Radicals
Authors: Hayakawa Taro , Nakashima Yuuki , Koyama Koichi , Ohdaira Keisuke , Matsumura Hideki 
Published: November 2012

ABSTRACTPhosphorus (P) doped ultra thin n+-layer is formed on crystalline silicon (c-Si) at low substrate temperatures of 80 – 350 °C using radicals generated by the catalytic reaction of phosphine (PH3) with a tungsten catalyzer heated at 1300 °C. The sheet carrier concentration obtained by Hall effect is in the range between 3×1012cm-2 and 8×1012cm-2. The distribution of P atoms obtained by secondary ion mass spectrometry (SIMS) indicates that P atoms locate within the depth of 4 nm from surface and the profile has almost the same distribution independent of any doping conditions such as substrate temperature or radical exposure time. The sheet carrier concentration is 1.15 – 2.12% of the amount of P atoms incorporated through the radical doping. The ratio of activated donors increases with substrate temperature during the radical doping, suggesting that P-related species bonded on the c-Si surface require thermal energy for their activation. Using the n+-layer formed by radical doping, the reduction of surface recombination velocity for n-type c-Si wafer is attempted. The effective minority carrier lifetime of the n-type c-Si sample covered with 6-nm-thick intrinsic amorphous Si (i-a-Si) layers on both side increases from 32 μs to1576 μs by the radical doping of P atoms to n-type c-Si surface, suggesting that the radical doping can be utilized for the formation of passivation layers on a-Si/ n-c-Si hetero-interface.
Fabrication of Organic Polymer Solar Cells by a Novel Solution-Based Vapor-like Mist Deposition Method
Authors: Ikenoue Takumi , Fujita Shizuo 
Published: November 2012

ABSTRACTOrganic solar cells with PEDOT:PSS hole transport layer or P3HT:PCBM active layer deposited by a novel solution-based mist deposition technique were fabricated and demonstrated. The device with mist-deposited PEDOT:PSS layer showed higher short circuit current density and power conversion efficiency than those of the one with spin-coated PEDOT:PSS layers. The device with mist-deposited P3HT:PCBM layer also performed with higher power conversion efficiency. The results encourage the promising potential of the mist deposition method for device fabrication.
Doping Effect on Chloroindium Phthalocyanine (ClInPc)/C60 Solar Cells
Authors: Wang Weining , Armstrong Neal 
Published: November 2012

ABSTRACTFor inorganic semiconductor solar cells, controlled doping is important because it can cause Fermi level shift of the inorganic semiconductor and achieve ohmic contact at the metal-semiconductor interface. In this paper we show that doping can also be used to shift Fermi level in organic semiconductors and cause changes in solar cell performance. We have made chloroindium phthalocyanine (ClInPc)/C60 heterojunction solar cells, where tetrafluoro-teracyano-quinodimethane (F4-TCNQ) is used to dope ClInPc layer. Ultraviolet photoemission spectroscopy (UPS) is used to investigate the ITO/ClInPc interfaces. The result shows that doping causes a Fermi level shift at the ITO/ClInPc interface as it does for inorganic semiconductors. As the doping increases, dark saturation current J0 of the solar cell increases, while open-circuit voltage Voc, short-circuit current Jsc and fill factor decreases. As a result, the efficiency of the solar cell decreases as doping increases. More UPS studies on ClInPc (doped with F4TCNQ)/C60 junction are needed to correlate the energy band diagram of the whole solar cell structure with the J-V characteristics.
Electrochemical studies and Thermodynamic Parameters of tris(2,2’-bipyridyl) ruthenium (II) in nonaqueous Solutions
Authors: Bolormaa Gendensuren , Battulga Munkhbat , Naranbileg Batjargal , Battsengel Baatar , Ganzorig Chimed 
Published: November 2012

ABSTRACTIn this study Ruthenium (II) tris (2, 2’-bipyridyl) complex in nonaqueous solution was studied by cyclic voltammetry and also its kinetic parameters were calculated. The redox reaction of ruthenium (II) trisbipyridyl complex is totally quasi-reversible and it can be described as a diffusion-controlled process. As a result of the redox reaction, the kinetic parameters of the electrode process such as diffusion coefficient (D), and heterogeneous rate constant (ks) were calculated. In addition, the different thermodynamic parameters such as standard free energy (ΔG#), enthalpy change (∆H#), and entropy change (∆S#) were determined and enthalpy change revealed the exothermic behavior of the electrode reaction. Both oxidation and reduction onset potentials of the ruthenium (II) trisbipyridyl complex was determined under the same experimental conditions to estimate the low ionization potential and electron affinity. The electrochemical and optical band gaps of the ruthenium (II) complex were compared.
Radioactive Waste and Spent Fuel Management in Argentina
Authors: Maset Elvira Rosa 
Published: November 2012

ABSTRACTSince its creation in 1950, the Argentine Atomic Energy Commission (CNEA), has worked on the development of applications for the peaceful use of nuclear energy. They include, among others, research and development activities in basic and nuclear technology areas, the operation of important facilities for the production of radioisotopes and the performance of tasks in connection with the nuclear fuel cycle, mining and uranium processing activities, manufacturing of fuel elements, production of heavy water and the operation of two nuclear power plants. Also demonstrating reprocessing programs have been developed.As a result of the above mentioned activities performed in the nuclear field by private and public entities, various types of radioactive waste have been and are produced during operation and maintenance of facilities and plants, and will be produced in their future decommissioning. CNEA is also responsible for the environmental remediation of the closed uranium mining and milling facilities and for the management of disused sealed sources from medical and industrial applications.Activities concerning radioactive waste management are carried on according not only to Nuclear Regulatory Authority requirements and International Atomic Energy Agency recommendations, but also to the national legal framework.The Law Nº 25.018, "Radioactive Waste Management Regime“(1998), created the National Program for Radioactive Waste Management (PNGRR), as part of CNEA organization.
The Role of Performance Assessment through the Multiple Phases of a Nuclear Waste Management Program
Authors: Bonano E.J. , Freeze G.A. , Appel G. 
Published: November 2012

ABSTRACTIn many countries, regulations for the management of nuclear waste require a performance (safety/risk) assessment to demonstrate the safety asserted to be provided by the sites/facilities proposed for handling, storing, and disposing of the wastes. However performance assessment can play a bigger role than solely demonstration of compliance with applicable safety standards in support of a regulatory decision (i.e., licensing of a waste management facility). Performance assessment can be an effective management tool during all phases of a waste management program: from development of national nuclear waste management policies; to programmatic environmental impact assessments associated with design and siting evaluations, site selection, and site characterization; to licensing and operation of facilities.International experience has demonstrated that nuclear waste management programs are long-term efforts, lasting at least two to three decades from initial policy development to licensing and commencement of waste management and disposal operations. This experience has also demonstrated that consistent attention to, and integration of, initial component studies are necessary to provide a comprehensive total system analysis for programmatic environmental impact assessments and for licensing.For nearly 40 years, Sandia National Laboratories has developed and applied a performance assessment methodology in numerous national and international nuclear waste management programs. These applications range from development and feasibility testing of environmental health standards to preliminary evaluation of waste disposal sites; to establishing the basis for demonstration of compliance; to informing licensing (compliance demonstration) decisions. In many of these applications the performance assessment methodology has also served as a management tool for confirming the added value of research and development investments.This paper presents examples to illustrate how performance assessment has been used as an effective management tool through multiple phases of a nuclear waste management program.
Main results of the French program on Partitioning and Transmutation of Minor Actinides
Authors: Poinssot Ch. , Boullis B , Rostaing C. , Warin D. 
Published: November 2012

ABSTRACTIn the framework of the successive 1991 and 2006 Waste Management Act, French government supported a very significant R&D program on partitioning and transmutation of minor actinides (MA). This program aims to study potential solutions for still minimizing the quantity and the hazardousness of final waste, by MA recycling. Indeed, MA recycling can reduce the heat load and the half-life of most of the waste to be buried to a couple of hundred years, overcoming the concerns of the public related to the long-life of the waste.Within this framework, this paper aims to present the most recent progress obtained in CEA on the development of innovative actinide partitioning hydrometallurgical processes in support of their recycling, either in an homogeneous mode (MA are recycled at low concentration in all the standard reactor fuel) or in an heterogeneous mode (MA are recycled at higher concentration in specific targets, at the periphery of the reactor core). Recovery performances obtained on recent tests in high active conditions of the so-called GANEX and DIAMEX-SANEX process will be presented and discussed in light of the potential P&T scenarios. Finally, recent developments regarding the recycling of the sole Am will be presented as well as the results obtained on highly active solutions for this so-called EXAM process.This set of results gives to the French government a portfolio of potential recycling processes which could be separately and progressively implemented if decided.
Assessing the role of spent fuel surfaces during leaching in presence of hydrogen by using Cr(VI) as a redox marker
Authors: Puranen A. , Ekeroth E. , Granfors M. , Low J. , Spahiu K. 
Published: November 2012

ABSTRACTIn many deep repository concepts spent nuclear fuel (SNF) will be disposed in canisters containing large amounts of iron. Intrusion of groundwater in a failed canister may occur under the presence of hydrogen, expected to be produced by the anoxic corrosion of iron. Compelling evidence now exists that hydrogen inhibits oxidative dissolution of SNF, the mechanism is however not fully understood. Hydrogen generally requires a catalyst in order to operate as a reductant. The metallic inclusions (ε-particles) present in SNF are a likely catalyst for this process due to their noble metal content. There is also evidence that the SNF UO2 matrix or doping of the UO2 with fission products can activate hydrogen. In most spent fuel experiments carried out under hydrogen, a decrease in concentration of all redox sensitive nuclides originating from a pre-oxidized layer is observed. Given their low concentrations and abundance in the fuel, it has however been difficult to detect any reductive precipitation on the fuel surfaces.In this study, Cr(VI) oxyanions were employed as a redox sensitive marker, as Cr(VI) is expected to precipitate as Cr(III) oxide on the catalyst that activates hydrogen.In the experiments PWR spent fuel (43 MWd/kgU) was leached in simulated groundwater (10 mM NaCl, 2 mM NaHCO3) at 25 and 70 ◦C under 5 MPa of hydrogen and dissolved Cr(VI). Dark green, Cr(III)-oxide was found to precipitate; mapping by electron microscopy (SEM-WDS) evidenced a Cr rich layer covering the fuel, suggesting that the whole fuel surface is catalyzing the reduction of chromium.
Development of Surface Marker System for the Observation of Microstructural Changes in Nuclear Graphite using Micro X-ray Tomography
Authors: Holmes Rosemary A. , Jones Abbie N. , McDermott Lorraine , Marsden Barry 
Published: November 2012

ABSTRACTCurrent energy demands and future energy needs are a growing industry which at present attracts a large amount of research and investment of which nuclear energy is an integral part. Eight new nuclear stations are proposed to be developed in the UK over the next ten years to meet this demand. In order for nuclear energy to sustain growth and development, nuclear decommissioning of first and second generation power stations needs to be addressed in the U.K. and worldwide. Presently the UK has 36 graphite moderated reactors as a result of the UK military and civil programs, which over the next twenty years will close. This will result in ∼99’000 tonnes of irradiated graphite waste for which no current national decommissioning strategy exists. The main issues associated with this waste are the large volume and activation products associated. By far the greatest inventory is from 3H and 14C. An EU Euroatom FP7 Program; CARBOWASTE was established in 2008 with the aim of developing treatment and disposal options for graphite.This research is based within CARBOWASTE, the main objectives are to understand the mechanisms involved in the production, location and removal of radioisotopes from nuclear graphite. Computed X-ray Tomography (CT) will be used in order to quantify the initial porosity in conjunction with thermal treatment (ex situ) in order to eventually identify the location of 14C within the matrix of irradiated graphite, through the preferential chemically controlled oxidation of graphite. Unirradiated Pile Grade A graphite samples have been laser and manually marked in order align the samples prior to and post thermal treatment to determine the degree of porosity changes and weight loss under a range of thermal oxidation parameters.
Modeling the Production of Tritium, Carbon-14 and Cobalt-60 in Irradiated Graphite from a UK Magnox Reactor
Authors: Black Greg , Jones A. N. , McDermott Lorraine , Marsden B. J. 
Published: November 2012

ABSTRACTThe Tritium, Carbon-14 and Cobalt-60 content of a trepanned sample from one of the Wylfa Magnox reactor have been experimentally determined using beta liquid scintillation counting and gamma spectroscopy. The WIMS9a reactor code and FISPACT-2007 neutron activation software have also been used to calculate this inventory for the sample, considering only a model which is isolated from the reactor circuit. Comparison between experimental and calculated results has shown that the calculated values for 14C are within 26%, 60Co within 24% and 3H 120%. These results show that the original impurity levels are sufficient to explain the experimentally determined end of life activity, without additional consideration of contamination from other materials in the reactor circuit, in this type of simulation. Additionally the calculations show that the production of 14C from 14N is approximately equal to that produced from 13C. These results are only applicable to the isolated system models developed here, and do not explicitly model existing reactor conditions, where external operating conditions may interact with the graphite and the core environment