bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Al Concentration on Growth of Antiphase Domains in Ti3Al
Authors: Koizumi Y. , Katsumura H. , Minamino Y. , Tsuji N.
Published: April 2011

Effects of Al-concentration on growth of antiphase domains (APDs) in Ti3Al crystals have been investigated using crystals with stoichiometric (Ti-25at.%Al) and Al-rich (Ti-33at.%Al) compositions in the temperature range from 973K to 1173K. The growth rate of APDs in the Al-rich crystal is several times higher than that in the stoichiometric crystals at all the temperatures investigated. While the time dependence of APD size obeys the parabolic-growth-law in the stoichiometric crystal, negative deviations from the law takes place at the late stage of the APD growth in the Al-rich crystal owing to the pinning effect of low-energy APB boundaries. APD boundaries lying on prism planes are formed in the Al-rich crystal annealed at 973K.
Polymeric Nanoscale All-Solid State Battery
Authors: Bullock Steven E. , Kofinas Peter
Published: April 2011

The advent of polymer electrolytes has provided a promising route to an all solid-state polymer battery. Such a battery would have greater safety, without potential discharge of liquid or gel electrolyte. Current battery configurations typically involve a metal anode, a solvent-plasticized polyelectrolyte, such as poly (ethylene oxide) (PEO), and a composite cathode. We have synthesized an A/B/C triblock copolymer which could have potential use as an all-solid state nanoscale polymer lithium battery. The polymeric battery was synthesized with an anode, electrolyte and cathode by synthesizing an A/B/C triblock copolymer whose microphase separation would form lamellar domains. These nanodomains contain cobalt oxide, a derivative of PEO synthesized by ring opening metathesis polymerization, and a spinel phase LiMn2O4 as the anode, electrolyte and cathode material, respectively. The first block contains cobalt oxide that stores lithium ion in a novel electrochemical reaction that allows use in a battery configuration. The second block is polyethylene oxide derived from an unsaturated crown ether, and is used for its high ionic conductivity. The third block contains LiMn2O4, which is currently being investigated as a potential cathode material because of its low toxicity and ease of preparation. The nanometer size domains in the battery can be used in unique applications in microelectronics. In addition, such size scale allows use of the battery in discrete circuits, reducing the amount of wiring necessary in conventional battery configurations.
Hole Transport In Self-Organized Oligosilane Thin Films With Highly Ordered Hopping Sites
Authors: Okumoto H. , Yatabe T. , Richter A. , Shimomura M. , Kaito A. , Minami N.
Published: April 2011

Self-organized oligosilane thin films possess molecular orientation normal to substrates with multilayered structure. This unique order of -conjugated molecules results in good hole transport properties. In the present work, carrier transport properties at low temperature are studied for 1,10-diethyldecamethylsilane polycrystalline films. Even at a temperature as low as 173 K, a time-of-flight transient photocurrent waveform showed a clear plateau and a sharp decay, whose shape is similar to that at room temperature. Their hole mobility followed Arrhenius type temperature dependence with a small activation energy of 0.09 eV. The hole mobility of 6.3×10-5cm2/Vs at 193 K was more than 2 orders of magnitude higher than that of typical polysilanes, which inevitably contain disordered structures hindering smooth carrier transport.
Electrophosphorescent Light Emitting Devices Using Mixed Ligand Ir(III) Complexes
Authors: Lee Hae Won , Das R. R. , Lee Chang-Lyoul , Noh Yong-Young , Kim Jang-Joo
Published: April 2011

We have fabricated phosphorescent light emitting devices using mixed ligand bisorthometalated Ir(III) complexes, chlorobis-(2-phenylpyridinato-N,C2')pyridineiridium(III) [Ir(Cl)(ppy)2(py)] and chlorobis-(2-phenylpyridinato-N,C2')triphenylphosphine iridium(III) [Ir(Cl)(ppy)2P(Ph)3] chlorobis-(2-phenylpyridinato-N,C2')tri-n-butylphosphine iridium(III) [Ir(Cl)(ppy)2P(n-Bu)3], where ppy is the orthometalating ligand. These complexes vary in their HOMO (highest occupied molecular orbital), LUMO (lowest unoccupied molecular orbital) and emissive states in accordance with the φ-accepting abilities of the non-orthometalating ligands. The lifetimes and EL spectrum of the devices were studied and compared.
Structural Dependence and Dynamics of White Luminescence in Multilayer Structures for White Organic Light Emitting Devices
Authors: Fujita Shizuo , Uesaka Ken-ichi , Fujita Shigeo
Published: April 2011

White electroluminescence (EL) spectra are carefully investigated in terms of the multilayer structures and a rule for designing the white luminescence is discussed. For a simple structure which consists of tris(8-hydroxyquinoline)-aluminum (Alq) and 1,2,3,4,5-pentaphenyl-1,3-cyclopendadiene (PPCP) emitting green and blue luminescence, respectively, as luminescent and electron transport layers, white luminescence appeared if the thickness of each layer was appropriately chosen. The luminescence efficiency was higher in PPCP, and therefore one of the structures effectively emitting white luminescence was designed as PPCP(10 nm)/Alq(40 nm). The 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) was then added to the PPCP/Alq structure intending to enhance red luminescence. We propose the structure where red luminescence is from the DCM as photoluminescence excited by the green and blue luminescence from Alq and PPCP, which was effective, compared to the PPCP/Alq/DCM stacking structure, in avoiding increase of the operating voltage. The importance of designing structures of organic white EL devices based on fundamental optical properties of the constituent layers and on luminescence dynamics is highlighted.
A 2” monochrome 64×96 passive matrix PLED
Authors: Huiberts Hans , Weijer Peter van de , Büchel Michael , Kok Margreet de , Vulto Simone , Meulenkamp Eric , Haskal Eliav
Published: April 2011

Royal Philips Electronics has recently launched the first commercially available polymer Light Emitting Diode (LED). In this paper, physical properties and phenomena will be discussed that must be taken into account during the selection of a polymer material and the choice of the device structure; for example, color, electron and hole mobility, polymer thickness, lifetime, leakage current and failure.
Three-Color Passive-Matrix Pixels Using Dye-Diffusion-Patterned Tri-Layer Polymer-Based LED
Authors: Long Ke , Pschenitzka Florian , Sturm J. C.
Published: April 2011

Dry dye-printing and solvent-enhanced dye diffusion were used to locally dope a previously spin-coated poly(9-vinylcarbazole) (PVK) polymer film with different dyes to fabricate side-by-side RGB OLED pixels. To reduce reverse leakage current and raise efficiency, a blanket tris-8-hydroxyquinoline aluminum (Alq) electron transport layer (ETL) was deposited over the polymer layer after the dye diffusion step, along with a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) hole/exciton blocking layer between the Alq and the PVK to ensure all light emission occurred from the doped polymer and not from the Alq. Devices with this tri-layer structure have an extremely low reverse leakage current (rectification ratio of 106 at +/- 10V) and a higher external quantum efficiency (∼1%) than single layer devices. A three-color passive-matrix test array with 300μm x 1mm RGB subpixels was demonstrated with this structure.
Photonic Crystals at Near-Infrared and Optical Wavelengths
Authors: Moroz Alexander
Published: April 2011

As demonstrated for the example of a diamond and zinc blende structure of dielectric spheres, small inclusions of a low absorbing metal with the volume fraction fm can have a dramatic effect on a complete photonic band gap (CPBG) between the 2nd-3rd bands. For example, in the case of silica coated silver spheres, the CPBG opens for fm ≍ 1.1% and exceeds 5% for fm ≍ 2.5%. Consequently, any dielectric material can be used to fabricate a photonic crystal with a sizeable and robust CPBG in three dimensions. Absorption in the CPBG of 5% remains very small (≥ 2.6% for λ ≥ 750 nm). The structure enjoys almost perfect scaling, enabling one to scale the CPBG from microwaves down to ultraviolet wavelengths.
Deliquescence Behavior of Multicomponent Salts: Effects on the Drip Shield and Waste Package Chemical Environment of the Proposed Nuclear Waste Repository at Yucca Mountain, Nevada
Authors: Pabalan Roberto T. , Yang Lietai , Browning Lauren
Published: April 2011

Thermodynamic calculations were conducted to determine the deliquescence behavior of salt mixtures and to simulate the evaporation of Yucca Mountain groundwaters. The results are consistent with published experimental data that show the deliquescence points of salt mixtures are lower than that of individual salts. For mixtures of NaCl and KCl salts, the deliquescence point of pure NaNO3 salt is an appropriate lower bound. However, mixtures containing magnesium and calcium salts have much lower deliquescence points than pure NaNO3. If magnesium and calcium salts are deposited on waste package and drip shield surfaces, it could lead to earlier initiation of aqueous corrosion than assumed by the DOE in its performance assessment abstractions. Such salt mixtures can be formed by evaporation of waters with compositions similar to some Yucca Mountain porewaters and would be characterized by low deliquescence relative humidity, high chloride concentration, and low concentrations of anions such as free (uncomplexed) nitrate and sulfate that could mitigate against the chloride-enhanced corrosion of the waste package. Evaporation of Yucca Mountain groundwaters also could lead to fluoride concentrations that are above the threshold for accelerated corrosion of the titanium drip shield.
Effects of Fluoride and Chloride Ions on Corrosion of Titanium Grade 7 in Concentrated Groundwaters
Authors: Pulvirenti A. L. , Needham K. M. , Adel-Hadadi M. A. , Barkatt A.
Published: April 2011

Titanium Grade 7 (Ti-7) was tested for both general and local corrosion in environments consisting of fluoride and chloride salts added to simulated groundwaters. Tests were conducted on both U-bends and disks in order to determine the extent of corrosion under stressed and unstressed conditions. The experiments were run over a broad range of temperatures and pH values for periods of up to 164 days. It was found that Ti-7 is susceptible to intergranular attack in some of the test solutions at moderately elevated temperatures, leading to conspicuous localized corrosion. Pitting was detected within 14 days, with pit depths on the order of 0.1 mm. Surface defects appeared to promote the initiation of pitting. The same environment caused stress corrosion cracking failure in a statically stressed U-bend.
Synthesis and Characterization of Cubic Zirconia, (Zr,Gd,Pu)O2, Doped with 238Pu
Authors: Burakov Boris E. , anderson Evgeniy B. , Zamoryanskaya Maria V. , Yagovkina Maria A. , Nikolaeva Elena V.
Published: April 2011

Crystalline ceramic materials based on the cubic zirconia structure have been proposed as candidate waste forms for the immobilization of weapons grade Pu and other actinides. To evaluate a resistance of these materials to self-irradiation for extended period of time, polycrystalline samples of gadolinia-stabilized cubic zirconia, (Zr,Gd,Pu)O2, doped with approximately 10 wt.% 238Pu were synthesized and characterized. Ceramic synthesis was done by sintering in air at 1500°C for 4 hours using starting precursor materials based on coprecipitated and then calcined oxalates of Zr, Gd, Pu. No differences were observed among the zirconia X-ray diffraction patterns that were obtained immediately after ceramic synthesis, or at 88 and 201 days later. MCC-1 leach tests were performed on ceramic specimens in deionized water at 90°C for 28 days. It was found that without correction for ceramic porosity the initial Pu mass loss (NL) was 0.04 g/m2. This increased to 0.35 and 0.37 g/m2, respectively, 180 and 260 days later. Results obtained allow us to confirm that actinide-doped cubic zirconia is highly resistant to accelerated self-irradiation and therefore, is an efficient material for actinide immobilization in deep geological repositories.
Sensitivity Studies of the Effect of Cladding Degradation on TSPA Results
Authors: Siegmann Eric , Devonec Eve
Published: April 2011

The Commercial Spent Nuclear Fuel (CSNF) cladding directly influences the dose by reducing the release rate of radionuclides compared to bare fuel. A cladding degradation model was introduced in the Total System Performance Assessment – Viability Assessment (TSPA-VA) and has evolved into the TSPA-SR (Sight Recommendation), Rev 00 and most recently the Supplemental Science and Performance Analyses (SSPA) models. TSPAs are large computer models that predict how the radionuclides might escape through the various barriers and migrate through the different geological regions and predict the dose to the critical population. The major components in the cladding degradation model are initial cladding failure, creep, stress corrosion cracking (SCC), localized corrosion, mechanical failures (due to seismic events and rock overburden) and cladding unzipping. In the bare fuel case, the dose is controlled by the failure rate of the waste packages (WPs), the solubility limits for certain radionuclides, and the rate of diffusion of the radionuclides through the cracks in the WPs. The cladding degradation model involves two steps, perforation followed by unzipping. Sensitivity studies have shown that cladding limits dose primarily by preventing dissolution of the UO2 fuel (when the cladding is not perforated). If all the cladding is assumed to be perforated and cladding unzipping occurs, the peak dose would be within 4% of that of bare fuel. The UO2 dissolution rate (the driving mechanism for cladding unzipping) is sufficiently rapid that assuming instant dissolution increases the dose by only 12% from the base case. In the current cladding degradation model, cladding accounts for a reduction in dose for the first 100,000 years of a factor of 16 when compared with bare fuel. This is because of the low initial cladding failure rate (2.1% including SCC and creep) and few failures from localized corrosion (late WP breach and limited water entering the WPs). Failure of the cladding by rock overburden accounts for an increasing trend in dose at times greater than 100,500 years. This mechanism increases the peak dose and delays the peak from approximately 200,000 to 300,000 years. In conclusion, the cladding degradation model, mostly through preventing water from contacting the UO2, reduces the dose predicted in the TSPA analysis.
Investigation of the Oxidation State of Uranium in Nuclear Materials and their Alteration Products
Authors: Buck Edgar C. , Colella Michael , Smith Katherine L. , Lumpkin Gregory R.
Published: April 2011

In this study, the oxidation state of uranium was investigated with Electron Energy-Loss Spectroscopy on the Transmission Electron Microscope. The oxygen K edge in a series of uranium-bearing phases was investigated and this technique was compared to an alternative method of using the relative intensities of the M4,5- edges of the actinides. Under controlled conditions, it is possible to obtain reliable oxidation state data on uranium solids; however, mixtures of oxidation states in a single compound cannot be distinguished with certainty.
Creep Analyses of Titanium Drip Shield Subjected to Rockfall Static Loads in the Proposed Geologic Repository at Yucca Mountain
Authors: Neuberger Brett W. , Greene Charles A. , Gute G. Douglas
Published: April 2011

The U.S. Department of Energy (DOE) has included a drip shield (DS) as a principle component of the engineered barrier system (EBS) for the proposed high-level nuclear waste geologic repository at Yucca Mountain, Nevada. The current DS design consists of titanium grade 7 (Ti Gr 7) plates and Ti Gr 24 support beams and bulkheads. The intended functions of the DS are to divert dripping water around and prevent rockfall damage to the waste package (WP). Sustained static loading of the DS may occur as a result of rockfall or drift collapse. These static loads may cause residual stress that approaches the yield stresses of the different DS materials. This level of residual stress would enable various creep mechanisms to transpire. A preliminary assessment of the potential for DS creep after a dynamic rock block impact is presented in this paper by expressing the DS residual Von Mises stress levels as fractions of the Ti alloy yield stress (YS). It was determined, using creep data from similar alloys that the residual stress levels within a DS after a 2-tonne rock block impact per DS segment length could cause creep in both the Ti Gr 7 plates and Ti Gr 24 bulkheads and support beams. The results of this study will assist the U.S. Nuclear Regulatory Commission (NRC) in evaluating the risk significance of the expected DS performance characteristics under actual repository conditions.
Corrosion Behavior of Carbon Steel in Bicarbonate (HCO3) Solutions
Authors: Dong Junhua , Nishimura Toshiyasu , Kodama Toshiaki
Published: April 2011

Carbon steel is considered in Japan the most promising candidate material for overpacks in high-level radioactive waste disposal. Effects of bicarbonate solutions on the corrosion behavior and corrosion products of carbon steel were investigated by electrochemical measurements; FT-IR spectra and XRD pattern analyses. The results of the anodic polarization measurements showed that bicarbonate (HCO3) accelerates the anodic dissolution and the outer layer film formation of carbon steel in the case of high concentrations, whereas it inhibits these processes in the case of low concentrations. The FTIR and XRD analyses of the anodized film showed that siderite (FeCO3) was formed in 0.5 to 1.0mol/L bicarbonate solution, and Fe2(OH)2CO3 in 0.1 to 0.2mol/L bicarbonate solution, while Fe6(OH)12CO3 was formed in 0.02 to 0.05mol/L bicarbonate solution. In all cases the pH value was around 8.3. The stability of these chemical compositions was discussed using a potential – pH diagram for the Fe-H2O-CO2 system.
Proof-of-Concept Flowsheet Tests for Cesium Removal from Tank Waste by Caustic-Side Solvent Extraction
Authors: Chamberlain David B. , Aase Scott , Arafat Hassan A. , Conner Cliff , Leonard Ralph A. , Regalbuto Monica C. , Vandegrift George F.
Published: April 2011

A caustic-side solvent extraction (CSSX) process to remove cesium from Savannah River Site (SRS) high-level waste has been developed through a joint program with Oak Ridge National Laboratory (ORNL), the Savannah River Technical Center (SRTC), and Argonne National Laboratory (ANL). The CSSX solvent consists of four components: (1) an extractant, a calixarene crown, calix[4]arene-bis(tert-octylbenzo-crown-6) designated BOBCalixC6, (2) a modifier, an alkyl aryl polyether, 1-(2,2,3,3,-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol, also called Cs-7SB, (3) a suppressant, an alkyl amine, trioctylamine (TOA), and (4) a diluent, Isopar®L. The solvent composition is 0.01 M BOBCalixC6, 0.50 M Cs-7SB, and 0.001 M TOA in Isopar®L. In this program we have developed and demonstrated a flowsheet that can be used to process SRS tank waste. To this end, a series of flowsheet tests were completed using simulated waste in a 2-cm centrifugal contactor at ANL. Three short-term (3-4 hours) tests were completed to demonstrate various aspects of the flowsheet. These tests were followed by a 71-h test where the solvent was recycled 42 times. In each case, we met or exceeded the key process goals: (1) cesium removal from the waste with a decontamination factor greater than 40,000, (2) concentration of cesium in the aqueous strip effluent by a factor of 15 using dilute nitric acid, and (3) stripping the solvent sufficiently to allow it to be recycled many times. The results from the 71-h test are discussed.
Synthesis and Evaluation of Uranium and Thorium Imprinted Resins
Authors: Noyes K.L. , Draye M. , Favre-Réguillon A. , Foos J. , Guy A. , Czerwinski K.R.
Published: April 2011

Ion exchange resins were created to complex either UO22+ or Th4+ from aqueous solutions. The nitrate salt of the target metal ion was dissolved in CCl2H2, while the resin was created around the ions to provide a unique structure based upon each metal. These resins were synthesized by a radical polymerization method, producing a reusable organic solid. The resins were qualified by obtaining values for their proton exchange capacities and data to define their complexation kinetics. Proton exchange capacities were determined using an indirect titration and were found to be 6.40 meq/g for the uranium-based resin and 4.61 meq/g for the thorium-based resin. Data for the resins' kinetics were obtained at pH 1.0, 2.5, 4.0, and 5.5. Results show that the templated resin rapidly removed the target actinides from aqueous solution under experimental conditions. Once loaded with metal, the ions can easily be removed with 5 M HNO3 and reused.
Effects of Reactor Decontamination Complexing Agents On Soil Adsorption-Column Studies (JJ5.4)
Authors: Serne R. J. , Cantrell K. J. , Kutnyakov I. V. , Lindenmeier C. W.
Published: April 2011

Previous studies show that some radionuclides present in reactor decontamination wastes form strong complexes with the organic complexing agents used to decontaminate reactor cores and piping. Further, the metal-ligand complexes exhibit reduced adsorption to soils. Flow through column tests were used to study the adsorption of metal-organic ligand complexes to two soils. The breakthrough curves for metals and organic ligands for four tests are shown. In all the column tests, the adsorption of the organic ligand-metal complex, or the free organic ligand and free metal (disassociated species) was reversible. That is, close to the total mass injected was recovered in the flushing stage with untraced background solution.

Two tests that used the iron oxide coated sand show complicated behavior that was interpreted as being caused by ligand (both EDTA and picolinate) interacting with the ferric oxides. The Ni-organic ligand complex in both cases appears to exchange Ni for Fe to some extent such that free Ni+2is produced and Fe (III)-organic complexes are formed that adsorb with different strengths. Further, we suspect that the organic ligand is dissolving some of the ferric oxide coatings and destroying sorption sites. The combination of all these reactions leads to rather complicated breakthrough curves. In tests with picolinate there is partial disassociation of the metal and ligand such that the breakthrough curves for the metal and ligand are different

A recommendation is made to not bury EDTA-laden decontamination wastes with cement. Another observation is that predictions that use simple constant Kdand constant source release constructs may not be exclusively conservative in predicting concentrations of contaminants in water down-gradient from disposal sites.
Durability of Pu-doped Titanate and Zirconate Ceramics Designed for Pu Immobilisation
Authors: Zhang Y. , Hart K.P. , Begg B.D. , Keegan E.A. , Day A.R. , Brownscombe A. , Stewart M.W.A.
Published: April 2011

Ceramics rich in pyrochlore-structured titanate and fluorite-structured zirconate phases designed for surplus Pu immobilisation, with and without process impurities, have been leach tested at 90°C in deionised water. The zirconates consist mainly of a defect-fluorite with secondary impurity-containing phase-powellite/scheelite (when sintered in Ar but not when sintered in air), a spinel or magnetoplumbite type phase, a glass forming silicate and a secondary U-rich phase (when sintered in air with added impurities). The pyrochlore-rich baseline titanate ceramic consists of pyrochlore, brannerite and Hf-rutile. When impurities are added zirconolite and a silicate glass are also present. The pyrochlore-rich titanate with 5 wt% of impurities sintered at 1300°C is highly durable. A well-densified zirconate version without impurities has comparable elemental releases to those of the titanate ceramic but a zirconate with 5 wt% of impurities sintered at 1400°C in air or Ar shows much higher U and Ca releases than the titanate ceramic. Sintering atmospheres, changing from Ar to air, can influence Pu and U release rates up to an order of magnitude. High Ga releases from zirconates with impurities show that the secondary phase containing Ga is not durable. The higher processing temperature and the apparent inability to incorporate many impurity elements suggest that zirconates are not as flexible as titanates in respect of processing conditions and aqueous durability.
Immobilized Low-Activity Waste Performance Assessment:2001 Version
Authors: Manna Frederick M. , Puighb Raymond J. , Finfrockb S.H. , Khaleelb R. , Baconc D.H. , Bergeronc M.P. , McGrailc B.P. , Wurstnerc S.K.
Published: April 2011

The Hanford Immobilized Low-Activity Waste Performance Assessment[1] examines the longterm environmental and human health effects associated with the planned disposal of the vitrified low-activity fraction of waste presently contained in Hanford Site tanks. The tank waste is the byproduct of separating special nuclear materials from irradiated nuclear fuels over the past 50 years. This waste is stored in underground single- and double-shell tanks. The tank waste is to be retrieved, separated into low-activity and high-level fractions, and then immobilized by vitrification. The U.S. Department of Energy (DOE) plans to dispose of the low-activity fraction in the Hanford Site 200 East Area. The high-level fraction will be stored at the Hanford Site until a national repository is approved.

This report provides the site-specific long-term environmental information needed by the DOE to modify the current Disposal Authorization Statement for the Hanford Site[2]. The original Disposition Authorization Statement was based on the 1998 version[3] of this performance assessment, which was conditionally accepted by DOE [4].

The calculations in this performance assessment show that a “reasonable expectation” exists that the disposal of the immobilized low-level fraction of tank waste from the Hanford Site can meet environmental and health performance objectives. As shown by the sensitivity studies, this conclusion remains valid despite the conceptual designs of the disposal facility and the ILAW packaging having undergone changes.
Characterisation of the Barrier Performance of Cements
Authors: Glasser F. P.
Published: April 2011

Portland and modified Portland cements are useful matrices for solidification and storage of wastes. Concrete containing cement is likely to be introduced into the repository. The further use of cement as an engineered barrier reduces materials incompatibility problems. Cement has a high internal pH and maintains a high buffering reserve of alkalinity. This in turn, reduces the solubility of many radionuclides. The source of the immobilisation (chemical, physical) is sensitive to nuclide species: sorption and precipitation are the main binding mechanisms. The conditioning action of cement could affect the performance of other engineered barriers. The deterioration of cements is discussed. Areas of research needs are highlighted.
Laser-Induced Photochemical Surface Modification of Intraocular Lens for Blocking After-Cataract
Authors: Tanizawa Katsuya , Murahara Masataka
Published: April 2011

The central part of polymethylmethacrylate (PMMA) lens was modified to be hydrophobic and the peripheral part, to be hydrophilic by photochemical reaction with ArF excimer laser and chemicals. PMMA has a high–transmittance property in the visible light and has been used as an intraocular lens. However, protein and fat are stuck onto the lens surface after a long-term insertion, which makes the surface get opaque; that is the after-cataract.

Accordingly, the central part of the lens was modified to be hydrophobic in order to protect the PMMA lens from fat and protein. And, the peripheral part was modified to be hydrophilic to develop an affinity for the tissue. Firstly, the central part of the lens was irradiated with ArF laser (147kcal/mol) in the presence of fluorine oil (perfluoropolyether) or CFn gas ambience. By this photochemical reaction, the CF3 functional group was substituted on the PMMA surface. Secondly, the peripheral part of the lens was irradiated with ArF laser (147kcal/mol) in the presence of water. By this photochemical reaction, the OH functional group was substituted on the PMMA.

The contact angle with the physiological salt solution was measured. The contact angle of the non-treatment sample was 83 degrees. The one treated with perfluoropolyether was 117 degrees at the laser shot number of 5000 and the laser fluence of 25 mJ/cm2. When using CBrF3 and CClF 3, the contact angles were both 91 degrees at the laser shot number of 5 and the laser fluence of 20 mJ/cm2. And, the one using the water was 14 degrees, less than the contact angle of the non-treatment sample.

It was confirmed that the exposure part of the PMMA surface with the laser was modified into hydrophobic or hydrophilic by the existence of oil and water. In conclusion, our study successfully demonstrated the production of the ideal intraocular lens.
Simulation of chiral liquid crystal self-assembly: analogies with the structural formation of biological fibrous composites
Authors: Luca Gino De , Rey Alejandro D.
Published: April 2011

The wide majority of biological fibrous composites exhibit twisted plywood architectures (planar or cylindrical) for mechanical reasons [1–5]. These supramolecular organizations originate from the passage of the extracellular matrix (surrounding the chiral fibrous molecules) trough a lyotropic cholesteric liquid crystalline mesophase during the structure formation process [1–5]. In this work, we used the well-established Landau-de Gennes theory of liquid crystals in order to develop a fundamental understanding of the supramolecular self-assembly process leading to the planar monodomain (defect-free) twisted plywood architecture [6]. Simulations illustrate the importance of constraining surface in the formation of defect-free (mechanically effective) composites. These results provide a better understanding of tissue morphogenesis which is highly desirable for the development of new bio-inspired synthetic composites.
Electroluminescent Textiles using Sputter-deposited Amorphous Nitride-Rare-Earth Ion Coatings
Authors: Kordesch M. E. , Richardson Hugh H.
Published: April 2011

Wide bandgap semiconductors have been sputter deposited onto non-crystalline substrates, low melting point materials, including polymer fibers, textiles and glasses. The semiconductors are amorphous and can be deposited over large (square meter) areas economically. The electro-optical properties of these materials are not defect limited, and do not require thermal processing. Alternating current electroluminescent device structures/coatings composed of rare-earth ion doped nitrides have been deposited onto point-bonded fabrics, polymer membranes, and polymer sheets. Light emission is detected from the coated fabrics over the entire visible range, UV and IR. A notable feature of fabric-based structures is the inclusion of ambient air in the fabric voids. Increased light emission intensity is obtained by extracting electrons from the plasma discharge during device operation. These fabrics do not require weaving, which could be difficult with semi-crystalline or brittle semiconductor materials. Multilayer assembly and bonding with continuous sheets, cladding, filling and or contact bonding are all available at any point in the fabric assembly. Non-woven, pin-bonded, materials may still function after some damage, e.g. rips or punctures, due to redundant connections at each pad. Further advantages are the simple incorporation of optically active ions, such as rare earths, high thermal conductivity, high breakdown voltage, and complete miscibility of the group III-A and -B nitrides, allowing bandgap engineering. The deposition process is scalable and may be applied to the fibers or yarns before or after fabric formation.
Amorphous Silicon Thin Film Transistors on Kapton Fibers
Authors: Bonderover Eitan , Wagner Sigurd , Suo Zhigang
Published: April 2011

The textile industry uses weaving to create very large quantities of fabric very quickly. The goal of our research is to use this well established technology to create complex large-area circuits quickly and efficiently. In our laboratory we have previously shown that amorphous silicon (a-Si) can be used to make thin-Film transistors (TFTs) on Kapton (a highly temperature-resistant polyimide from DuPont). We also previously showed that these TFTs can survive mechanical loads. A process has been designed to make “TFT fibers” by fabricating a-Si TFTs on Kapton. A special TFT geometry has also been developed. The structure consists of 3 large gold contact pads – one for each terminal of the TFT – running along the fiber. These contact pads allow connections to be made between TFT fibers using conductor fibers – Kapton fibers coated only with gold. The TFT fabrication process is based on a low temperature (150°C) Plasma Enhanced Chemical Vapor Deposition (PECVD) process. The TFTs are fabricated on a Kapton sheet from which flat fibers are made by the slit film technique. So far the best method for cutting a Kapton sheet into fibers has been plasma etching. We will describe the electronic characteristics of these TFTs as well as the electrical characteristics of the contacts between TFT fibers.
Preparation and Characterization of Nanometer-scale Polycarbonate Fibers: Bead Formation
Authors: Shawon Jamila , Sung Changmo
Published: April 2011

Electrospinning is a superior process compared to other conventional spinning methods for the production of fibers in the sub-micron to nanometer scales. Such fiber membranes have exceptionally large surface areas and small pore sizes. The process requires an electrostatic force, which induces charges on the liquid droplet of the polymer solution or melts and therefore overcomes the surface tension and viscoelasticity forces to create an electrically charged jet. When the jet dries or solidifies, an electrically charged fiber remains, which can be directed or accelerated by the electrical forces and then collected in non-woven fiber membrane or other useful shapes. The present research work demonstrates the electrospinning of polycarbonate solution with solvent mixtures THF (Tetrahydrofuran) and DMF (Di-methyl formamide) to produce nanometer scale polycarbonate fibers. The solvent mixture of THF and DMF was the major parameter for producing nano-polycarbonate fibers along with the formation of byproducts beads. The electrostatic voltage, viscosity and surface tension also showed significant effect on bead formation and bead density. The microstructures of the polycarbonate beads were quantitvely investigated by Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM).
Electrotextiles - Present and Future
Authors: Natarajan Karthikeyan , Dhawan Anuj , Seyam Abdelfattah M. , Ghosh Tushar K. , Muth John F.
Published: April 2011

Electrotextiles have attracted increasing attention in recent years. The combinations of textile structures that are lightweight, flexible, conformable, and strong, with electronics have aroused keen interest from many disciplines. With technological innovations appearing in both textile and electronics, integration of these has started giving benefits. Innovations like the sensate liner, soft switches and smart composites have found many applications in sports, healthcare, military, aerospace engineering, civil engineering and many other fields. The purpose of this paper is to provide an overview of various electrotextile products available and explain their functionality. Additionally, the paper provides a review of future electrotextile products, which are in the developmental phase, and the challenges that need to be addressed by researchers and industry.
Thin-Film Solid-State Lithium Battery for Body Worn Electronics
Authors: McDermott Joseph , Brantner Paul C.
Published: April 2011

Infinite Power Solutions manufactures a flexible rechargeable micro ampere-hour solidstate battery based on thin-film Lithium technology where the battery can be engineered into the product for life as a cost effective solution with “the battery that never needs to be replaced”. The performance characteristics of the battery combined with low power electronic textile applications will require “A Different Way of Thinking About Batteries” relative to battery management and innovative methods of recharging the battery (such as charging the battery whenever the materials are washed and dryed). This paper will review the characteristics of the battery specifically in relation to power generation for flexible electronic materials and the integration issues for a thin-film battery for flexible electronic materials.
Synthesis of Semi-Conducting Nanoparticles within a Protein Template
Authors: Wong Kim K. W. , Mayes Eric L.
Published: April 2011

The ability to synthesise and tune photoresponsive and photoredox II-VI semi-conductor nanoparticles by quantum confinement is a continuously and rapidly developing area. Chemical methods are useful in producing dispersions of nanoparticles of uniform size in many organic solvents. Such synthetic methods employ the use of reverse micelles [1,2], phospholipid vesicles[3,4] or capping agents[5,6]to restrict particle size and growth to the nanometre regime.

The production of super lattice assemblies, through, for example the use of controlled crystallisation [7], Langmuir monolayers[8], Langmuir Blogget films[9], and self assembled short chain dithiol monolayers[10] on gold substrates has also received attention in the past. This latter approach potentially opens the way for self assembled electro-luminescent devices[11].

The ability to couple organic self assembly and inorganic nano-synthesis could also provide a route toward the chemical synthesis of an organised array of quantum-confined semiconductors. An aspect of this synthesis with construction approach is the possible coupling of biological templating systems to produce biomimetic materials [12,13]. In fact, an example would be the stabilised CdS nanoparticles in yeast binding to phytochelatin peptides which are secreted in response to metal toxicification [14].
The Role of Nanoscale Silicon in Optical Interconnects
Authors: Fauchet Philippe M.
Published: April 2011

The semiconductor industry association roadmap has identified interconnects as a major barrier to progress starting in 2010. Optical interconnects (OI) offer an attractive solution for chip-to-chip communications, however there is no general agreement on how to design them. Eventually, OI may also perform a large amount of intra-chip clocking and signaling, which implies that any chip-to-chip OI system must be designed to be compatible with intra-chip OI, from the points of view of manufacturability, architecture, and device design. We are exploring the use of nanoscale silicon for OI. This paper reports progress toward the demonstration of two basic building blocks of an OI system, namely a Si laser and a Si-based modulator.
Polymorphous silicon nanowires synthesized by plasma-enhanced chemical vapor deposition
Authors: Zeng X.B. , Liao X.B. , Diao H.W. , Hu Z.H. , Xu Y.Y. , Zhang S.B. , Chen C.Y. , Chen W.D. , Kong G.L.
Published: April 2011

Polymorphous Si nanowires (SiNWS) have been successfully synthesized on Si wafer by plasma enhanced chemical vapor deposition (PECVD) at 440°C, using silane as the Si source and Au as the catalyst. To grow the polymorphous SiNWS preannealing the Si substrate with Au film at 1100 °C is needed. The diameters of Si nanowires range from 15 to 100 nm. The structure, morphology and chemical composition of the SiNWS have been characterized by high resolution x-ray diffraction, scanning electron microscopy, transmission electron microscopy, as well as energy dispersive x-ray spectroscopy. A few interesting nanowires with Au nanoclusters uniformly distributed in the body of the wire were also produced by this technique.
Fabrication of Ordered Metallic Nanocluster Arrays Using a Focused Ion Beam
Authors: McMahon Matthew D. , Hmelo Anthony B. , Lopez Rene , Ryle Wesley T. , Newton Allen T. , Haglund Richard F. , Feldman Leonard C. , Weller Robert A. , Magruder Robert H.
Published: April 2011

We have fabricated ordered arrays of gold nanocrystals on FIB-processed silicon substrates using electroless deposition. We have also fabricated ordered arrays of silver nanocrystals on silicon with diameters 40–60 nm separated by 180 nm center-to-center, using pulsed-laser deposition (PLD) to deposit silver on the substrate. The metal nanocrystal arrays are characterized using SEM as well as AFM and energy dispersive x-ray (EDX) analysis. AFM confirms particle sizes measured in SEM, and EDX analysis demonstrates that Ag preferentially clusters at sites that have been damaged by the ion beam. These results suggest that the FIB-PLD combination can be used to create ordered arrays of Ag nanocrystals with diameters of 10 nm or less.
Proton Induced Structuring of a Photostructurable Glass
Authors: Abraham Meg , Gomez-Morilla Inmaculada , Marsh Mike , Grime Geoff
Published: April 2011

The use of photons to create intricate three-dimensional and buried structures [1] in photo-structurable glass has been well demonstrated at several institutions [2]. In these instances the glass used whether it be Foturan™, made by the Schott Group or a similar product made by Corning Glass, forms a silver nucleation sites on exposure to intense UV laser light via a two-photon process. Subsequent annealing causes a localized crystal growth to form a meta-silicate phase which can be etched in dilute hydrofluoric acid at rates of 20 to 50 times that of the unprocessed glass. The same formulation of glass can be “exposed” using a particle beam to create the nucleation site. In the case of particle beam exposure, experiments have shown that the mechanisms that cause this initial nucleation and eventual stochiometric transformation, after annealing, depend largely on the beam energy.
DFB Structures in Electroactive Conjugated Polymers realized by Soft Lithography
Authors: Moderegger Erik , Gaal Martin , Gadermaier Christoph , Plank Harald , List Emil J.W. , Pogantsch Alexander , Güntner Roland , Scherf Ullrich , Leising Günther
Published: April 2011

The realization of a polymeric injection laser diode is an important aim in organic electronics. A crucial step towards this goal lies in the understanding and fabrication of feedback structures for lasers. Such feedback structures may be fabricated either in the substrate or directly in the active polymer layer.

Soft Lithography has proven itself as a useful tool to pattern a wide variety of materials. Typically one uses elastomeric molds (stamps) to pattern materials and structures whereby dimensions as low as 30 nm can be achieved.

Different types of Soft Lithographic processes are applied to produce optical feedback structures for optically pumped laser arrays.
Low Temperature Photoluminescence Studies of Narrow Bandgap Gaassbn Quantum Wells on GaAs
Authors: Waldrip K.E. , Jones E.D. , Modine N.A. , Jalali F. , Klem J.F. , Peake G.M.
Published: April 2011

We present low-temperature (T = 4K) photoluminescence studies of the effect of adding nitrogen to 6-nm-wide single-strained GaAsSb quantum wells on GaAs. The samples were grown by both MBE and MOCVD tech-niques. The nominal Sb concentration is about 30%. Adding about 1 to 2% N drastically reduced the bandgap energies from 1 to 0.75 eV, or 1.20 to 1.64 μm. Upon performing ex situ rapid thermal anneals, 825°C for 10s, the band gap energies as well as the photoluminescence intensities increased. The intensities increased by an order of magnitude for the annealed samples and the band gap energies increased by about 50 - 100 meV, depending on growth temperatures. The photoluminescence linewidths tended to decrease upon annealing. Preliminary results of a first-principles band structure calculation for the GaAsSbN system are also presented.
Influence of low-energy electron beam irradiation on defects in activated Mg-doped GaN
Authors: Gelhausen O. , Phillips M. R. , Klein H. N. , Goldys E. M.
Published: April 2011

CL spectroscopy studies at varying temperatures and excitation power densities as well as depth-resolved CL imaging were conducted to investigate the impact of low energy electron beam irradiation (LEEBI) on native defects and residual impurities in metal-organic vapor phase epitaxy (MOVPE) grown Mg-doped p-type GaN. Due to the dissociation of (Mg-H)0 complexes, LEEBI significantly increases the (e,Mg0) emission (3.26 eV) at 300 K and substantially decreases the H-Mg donor-acceptor-pair (DAP) emission (3.27 eV) at 80 K. In-plane and depth-resolved CL imaging indicates that hydrogen dissociation results from electron-hole recombination at H-defect complexes rather than heating by the electron beam. The dissociated hydrogen atoms associate with nitrogen vacancies, forming a deeper donor, i.e. a (H-VN) complex. The corresponding deeper DAP emission with Mg centered at 3.1 eV is clearly observed between 160 and 220 K. Moreover, a broad yellow luminescence (YL) band centered at 2.2 eV is observed in MOVPE-grown Mg-doped GaN after LEEBI-treatment. It is suggested that a combination of LEEBI-induced Fermi-level downshift due to Mg-acceptor activation and simultaneous dissociation of gallium vacancy-impurity complexes, i.e. (VGa-H), is responsible for the observed YL.
ZnO and ZnMgO Growth by Molecular Beam Epitaxy
Authors: Yano Mitsuaki , Ogata Ken-ichi , Yan FengPing , Koike Kazuto , Sasa Shigehiko , Inoue Masataka
Published: April 2011

Characteristics of the ZnO and ZnMgO films grown by radical-source molecular beam epitaxy are reported. The ZnO films on a-plane sapphire substrates had a superior quality in crystallographic, optical and electrical properties, and n-type doping with Al was successfully performed up to 1020 cm–3. The Mg-content of ZnMgO alloys was found to be controlled by a simple growth mechanism as a function of Mg-cell temperature. The alloying in the ZnO-rich region resulted in single-crystalline growth although the photoluminescence characteristics at x = 0.22 suggested the presence of microscopic phase separation. Single-crystalline growth was also achieved on Si (111) substrates by using a CaF2 buffer layer to protect the Si-surface from oxidation.