bluuebunny/crossref_metadata_2025 huggingface dataset:
Tribology of Material Contacts under Dynamic Loading, Studied by Electrical Resistance Measurement
Authors: Luo Xiangcheng , Chung D.D.L.
Published: April 2011

The tribology of material contacts under cyclic compression in the direction perpendicular to the plane of the contact was studied by measurement of the contact electrical resistivity of the contact during the dynamic loading. The real-time monitoring allowed observation of both reversible and irreversible effects. The material contacts studied were those involving steel, carbon fiber polymer-matrix composite, cement mortar and graphite, due to their relevance to fastening, concrete structures, electric brushes and electrical pressure contacts. Correlation was made between the contact resistivity and the occurrence of elastic/plastic deformation at asperities. The interfacial structure was found to depend on the stress and the loading history.
Ordering Effect of Lithium Ions in a Self-Assembled Hybrid System
Authors: Retuert P.J. , Fuentes S. , González G. , Yazdani-Pedram M.
Published: April 2011

By blending 3-aminopropyl-siloxane oligomers (pAPS) with chitosan (CHI) self-assembled hybrid films have been obtained. The influence of the incorporation of LiClO4 on the morphology of these transparent and flexible hybrid films has been studied. It was found that when this salt is added in amounts slightly over the limit of the maximal homogeneous incorporation a process of anisotropical crystallization begins. For a hybrid with composition CHI/pAPS/LiClO4 = 0.6/1/0.8M, Video-Enhanced Differential Interference Contrast microscopy (VEC-DIC) of the first three layers of the films showed that each layer have oriented patterns with angles of exactly 60 degrees between the planes. These results in combination with FTIR analysis of the products indicate that lithium ions behave as strong structure directing agent. This system can be considered as a biomimetic model for biomineralization processes. An interaction scheme comprising the components of this hybrid system is proposed.
Rod-like Dinuclear Ruthenium Complexes for Dye-sensitized Photovoltaics
Authors: Mosurkal Ravi , He Jin-An , Kumar Jayant , Li Lian , Walker John , Samuelson Lynne
Published: April 2011

Ruthenium complexes with tridentate terpyridine type ligands have many structural advantages over the complexes with bipyridine ligands. Polynuclear ruthenium complexes prepared using these terpyridine ligands bridged with phenylene rings are potential candidates for photosensitization in dye-sensitized photovoltaic cells. In this study, we have carried out synthesis, characterization and theoretical modeling of rigid, rod-like homometallic dinuclear ruthenium complexes using terpyridine and bipyridine ligands. The photophysical and photovoltaic properties have been investigated. These supramolecular dyes are found to be efficient photosensitizers in dye-sensitized photovoltaic cells when a liquid electrolyte is employed.
Improvement of Power Efficiency in Organic Electroluminescent Devices
Authors: Ganzorig Chimed , Fujihira Masamichi
Published: April 2011

In order to improve power efficiency of organic electroluminescent (EL) devices, i.e., ITO/TPD/Alq3/Al, enhanced electron and hole injection at Alq3/Al and ITO/TPD interface, respectively, was attempted by designing proper charge injection at both interfaces. Enhanced charge recombination at TPD/Alq3 was also demonstrated. Here, ITO, TPD, Alq3, and Al are abbreviations for indium-tin-oxide, N,N'-diphenyl-N,N'-bis(3-methyl-phenyl)-1,1'-biphenyl-4,4'-diamine, tris(8-hydroxyquinoline) aluminum, and metal aluminum, respectively. Enhanced electron injection by introducing a thin layer of Li salts of fluoride, acetate, and benzoate was described. We have found that the electron injection was improved in the order of Li+, Na+, K+, Rb+, and Cs+, and Cs salts exhibited the best EL performance. Chemical modification of ITO has been attempted to fine-tuning the work function of ITO in order to reduce hole injection barrier height. EL characteristics were improved dramatically using ITO modified with H-, Cl-, and CF3-terminated benzoyl chlorides. By using reactive -COCl groups, ITO surfaces were covered quickly and the work function of ITO was changed widely depending upon permanent dipole moments introduced in para-position of benzoyl chlorides. Correlation between the change in the work function of ITO and the EL characteristics was examined. The improvement of charge recombination was attained by increasing the interfacial areas, i.e. introducing a mixed layer of TPD and Alq3, or inserting a thin film of rubrene with a higher recombination efficiency.
Nano-Structure Control of Cathode Buffer-Layers and Luminescent Properties of Organic Electroluminescent Device
Authors: Shinbo K. , Sakai E. , Kaneko F. , Kato K. , Kawakami T. , Tadokoro T. , Ohta S. , Advincula R. C.
Published: April 2011

Organic light emitting diodes (OLEDs) containing cathode buffer layers of nanometer thickness were fabricated and their electrical and emitting properties were investigated. The OLEDs have an indium tin oxide (ITO) anode/ copper phthalocyanine (CuPc) / N, N'-dephenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine (TPD) / 8- hydroxyquinoline aluminum (Alq3) / buffer layer / Al cathode structure with the buffer layers made from alternating thin films of Alq3 and Al with nanometer thickness. Improvement of driving voltage and the efficiency for the devices were observed by insertion of the buffer layer. It was estimated that some modulations of the Schottky barrier at the Alq3 and the Al cathode interface were induced due to the insertion of the buffer layer and it caused an enhancement of electron injection from the Al cathode. A model of the band structure at the buffer layer was proposed.
Multi-layer contacts for organic light-emitting diodes with enhanced injection efficiency
Authors: Bakueva Ludmila , Musikhin Sergei , Sargent Edward H. , Shik Alexander
Published: April 2011

A low level of electron injection is one of the major obstacles to achieving high-efficiency organic light-emitting diodes. With the goal of improving injection characteristics, we fabricated and investigated herein multi-layer contacts which included a tunnel-transparent dielectric layer of nanometer thickness. Polymer layers were prepared by the spin-coating method and dielectric and metallic contact layers grown by vacuum deposition. The voltage drop at this layer shifts the metal Fermi level relative to the polymer molecular orbitals responsible for the carrier transport, increasing the injection efficiency. The introduction of a suitably chosen dielectric layer results in an increase in the injection efficiency by up to a factor of several tens.

Further sophistication of the injecting contacts consists in creating and additional intermediate thin metallic layer playing the role of the third, base electrode, similar to hot-electron transistors with metallic base. Additional bias applied to the base electrode permits variable injection efficiency and quantum yield over a wide range.
Novel Hybrid Covalent / Ionic Self-Assembly Technique for Improved Second-Order Nonlinear Optical Films
Authors: Neyman P. J. , Guzy M. , Shah S. M. , Davis R.M. , VanCott K. E. , Wang H. , Gibson H. W. , Brands C. , Heflin J.R.
Published: April 2011

Ionically self-assembled monolayer (ISAM) films have been shown to spontaneously produce noncentrosymmetric ordering that gives rise to a substantial second order nonlinear optical (NLO) response. Typically, the ISAM films for NLO response are an assemblage of bilayers of oppositely charged polymers whose thickness can be controlled through variation of pH and ionic strength of the immersion solutions. Here, we investigate the effects of replacing the NLO-active polymer layers with layers of monomeric chromophores containing ionic and covalent bonding sites. Films fabricated exclusively using polyelectrolytes contain some fraction of both randomly oriented and anti-parallel oriented chromophores. We have examined the incorporation of monomeric chromophores into ISAM films in order to increase the net polar orientation of the chromophores and reduce bilayer thickness.
Conjugated polymers for thin film coating process
Authors: Tang Zhexiong , Li Wenguang , Nowak Cheryl , Yang Sze
Published: April 2011

In this paper, we present the syntheses of the conjugated polymers of different “effective molecular weights.” The goal is to be able to optimize the thin film coating process without compromising the electronic, optical and electroactive properties.

Our strategy for controlling the effective molecular weight is to synthesize a double-strand conducting polymer that is an inter-polymer complex of a polymeric dopant and a conjugated polymer. The first strand of the two-strand complex is either a polyaniline or a polypyrrole chain, while the second strand is a poly(acrylic acid). The molecular weight of poly(acrylic acid) is used as a parameter for adjusting the coating and film-forming properties.

We found that the inter-polymer complexes are dispersible in water. The dispersion stability is strongly dependent on the molecular weight of the poly(acrylic acid) strand. The dispersion is more stable for polymers synthesized with higher molecular weight of poly(acrylic acid). We also found that the particle size and particle morphology are dependent on the effective molecular weight.
Enhanced Photovoltaic Response in Ionically Self-Assembled Monolayer Thin-Film Devices
Authors: Marciu Daniela , Miller Michael B. , Kozikowski Carrie , Heflin J. R. , Cho Sung , Reid Beth A. , Kuroda Kaori , Graupner Willi , Wang Hong , Gibson Harry W. , Davis Richey M.
Published: April 2011

We describe detailed studies of ionically self-assembled monolayer (ISAM) photovoltaic (PV) devices incorporating various electron acceptor materials, such as fullerenes and phthalocyanines. Excitons are generated when the conducting polymer is irradiated, and the electron acceptors aid in dissociating the electron/hole pairs before they can radiatively recombine, thus improving the efficiency of the PV process. The ISAM technique allows the deposition of conducting polymer and electron acceptor materials in alternating layers of nanometer-scale thickness. This ensures that every photoexcited electron-hole pair is in proximity to an electron acceptor, thus minimizing electron-hole recombination and increasing the photocurrent. The individual thickness of each monolayer and the interpenetration of adjacent layers can be precisely controlled through the parameters of the electrolyte solutions. Using the ISAM technique, we have demonstrated that it is possible to create ultrathin films (100 nm) of PV material that have enhanced efficiencies.
Cesium Ion Implantation in Single Crystal Yttria-Stabilized Zirconia (YSZ) and Polycrystalline MgAl2O4-YSZ
Authors: Zhu S. , Zu X.T. , Wang L.M. , Ewing R.C.
Published: April 2011

YSZ and MgAl2O4-YSZ composite are two promising materials as in the inert matrix nuclear fuel for the incineration of plutonium. In this study, 400 keV Cs ions were implanted to a fluence of 1×1017 ions/m2 in both materials in order to investigate the retention behavior of fission product at elevated temperature. The implantations were completed at room temperature for the YSZ and 973 K for MgAl2O4-YSZ, respectively. Subsequent annealing at 1273 K was performed after a room temperature implantation of YSZ. After annealing, a high density of gas bubbles formed with diameter from 3 to 40 nm from the surface to a depth of 150 nm in the YSZ matrix. The swelling due to bubbles formation was estimated to be 2.5%. In situ TEM was employed during high temperature ion implantation of the MgAl2O4-YSZ composite. A high density of small bubbles with 5 nm in diameter formed in the MgAl2O4 and YSZ grains after an ion dose of 1×1017 ions/cm2. There was no preferential precipitation along grain boundaries. Electron Paramagnetic resonance (EPR) spectroscopy was used to investigate the type of defects that formed in the YSZ matrix.
Chemical Interactions in the Near-Field of a Spent Fuel Repository - Preliminary Results from a Long-Term Laboratory Experiment
Authors: Aalto H. , Carlsson T. , Kumpulainen H. , Lehikoinen J. , Muurinen A.
Published: April 2011

A ten-year-long laboratory experiment was recently started in order to study interactions between the groundwater, the bentonite, and the canister in the near-field of the planned Finnish repository for spent nuclear waste. The experimental set-up consists of a number of samples containing sodium MX-80 bentonite and cast iron cylinders placed in copper vessels. The bentonite stays in contact with an external solution, either distilled water or a 0.5 M NaCl solution, via metal sinters. The experiments are performed under anoxic conditions (N2 atmosphere) at ambient room temperature (∼30 °C). The experimental measurements focus mainly on the development of (1) the water chemistry, (2) the cast iron corrosion, and (3) the diffusion of corrosion products inside the bentonite, since these processes are the most likely ones to produce detectable changes during the ten-year-long programme.

The first analyses, after 9 months, showed that the iron corrosion had started and that the corrosion products had migrated into the bentonite. The corrosion products could not be identified by XRD, which either meant that the material was amorphous or present in concentrations too low to be detectable. The analyses of the gas phase indicated the presence of hydrogen, which most probably was the result of the iron corrosion. The compositions of the external water and the porewater were determined with regard to the major species of interest. A closer evaluation of the results will not be given until more data are at hand.
Atmosphere Processing Effects on Titanate Ceramics Designed for Plutonium Disposition
Authors: Stewart M.W.A. , Vance E.R. , Jostsons A. , Finnie K. , Day R.A. , Ebbinghaus B.B.
Published: April 2011

Baseline formulation titanate ceramics for surplus Pu disposition are based upon a target mineralogy of 95 wt.% pyrochlore (Ca0.89Gd0.22Hf0.23Pu0.22U0.44Ti2O7) plus 5 wt.% Hf-doped rutile (∼ Ti0.9Hf0.1O2), where Ce is used as an analogue for Pu and U, and Th for Pu. Typically, Pu/U, Th/U and Ce/U-baseline samples form major pyrochlore, plus minor brannerite (AnTi2O6) and rutile. Ce/Ce-baseline ceramics were similar but did not form brannerite. Sintering in air produced more U5+ in the ceramics than sintering in Ar. In the pyrochlore the charge compensation for U5+ principally occurred by an increase in Ca2+ and decrease in Ti4+ and Th4+. In the matrix these phase compositional changes result in an increase in brannerite content of the ceramic at the expense of pyrochlore in the air sintered ceramic relative to the Ar sintered sample. Sintering in reducing 3.7% H2 in Ar atmospheres eliminates the brannerite and rutile and results in 2M-zirconolite and perovskite in addition to the major pyrochlore phase. Varying the sintering temperature between 1250°C and 1400°C had little effect on the phase chemistry other than slightly incomplete reactivity of coarse actinide oxide at the lower sintering temperatures and a general increase in density (to ∼ 1350°C) and grain size with increased sintering temperatures. Th4+ appears to be a good analogue for Pu4+ from a crystal chemistry aspect.
The Use of Cerium Valence State for Evaluation of Accessory Minerals Durability to Radiation Damage
Authors: Bogdanov Roman V. , Zaytsev Yuri M. , Sergeev andrey S.
Published: April 2011

Cerium-actinide bearing natural minerals which demonstrate their long-time physicochemical durability under the environment effect would be considered as analogues of actinide ceramic waste forms. Radiation damage of crystalline materials causes oxidation of cerium from initial Ce(III) to Ce(IV). Therefore, cerium valence state in actinide-cerium bearing natural minerals in some cases reflects the resistance of such minerals to radiation damage. Cerium valence state was determined in the following natural minerals of similar age and similar U-Th-contents: monazite (four samples), britholite (two samples), and aeschynite (one sample). The method of chemical shifts of X-ray emission (CeKá1 line) was used. The following contents of Ce(IV) were observed: more then 30 % in britholite, 11 % in aeschynite, 0 % in monazite. The results obtained suggest that durability of these actinide host phases with respect to radiation damage decreases in the monazite-aeschynite-britholite series.
Effects of Heavy Metal Ions on Corrosion of Titanium Grade 7 In Concentrated Groundwaters
Authors: Pulvirenti April L. , Needham Karen M. , Adel-Hadadi Mohammad A. , Marks Charles R. , Gormana Jeffery A. , Barkatt Aaron.
Published: April 2011

A Titanium Grade 7 (Ti-7) drip shield is being considered for use in the potential nuclear waste repository at Yucca Mountain, Nevada. The purpose of the drip shield is to keep water from reaching the surfaces of the canisters containing nuclear waste. Among the species that may be expected to be present in the water are heavy metals. This paper explores the effects of five species, lead, mercury, cadmium, tin and sodium, on the dissolution rate of Ti-7. The results of these tests indicated that lead, mercury, cadmium and tin ions do not significantly accelerate the general corrosion of Ti-7 under the conditions studied. A highly concentrated solution of NaOH was found to cause significant dissolution of Ti-7. Such a solution is a reasonable approximation of possible service environments.
Alteration-Phase formation and Associated Cesium Release During Alteration of R7T7 Waste Glass
Authors: Inagaki Y. , Idemitsu K. , Arima T. , Maeda T. , Ogawa H. , Itonaga F.
Published: April 2011

Static corrosion tests were performed with an inactive HLW glass of R7T7 type in order to evaluate alteration-phase formation and associated Cs release during the glass corrosion. The tests were performed in NaOH solutions at elevated temperatures in order to accelerate the corrosion. Crystalline phases formed in the corroded glass were analyzed by use of XRD, in addition to the solution analysis. The results indicated that; 1)Analcime or Na-beidellite or both of them form during the corrosion depending on the conditions, 2)Si rich amorphous phases are contained in the alteration-phases, 3)In addition to solution pH, solution concentrations of Na and K sensitively affect formation of analcime and Na-beidellite, 4)Analcime formation accelerates the glass corrosion, 5)Most of Cs in the glass is retained in the alteration-phases by sorption onto Na-beidellite or incorporation into amorphous phases and pollucite
Assessment of Spent Fuel of Alfa Class Nuclear Submarines
Authors: Bugreev M.I. , Efimov E.I. , Ignatiev S.V. , Pankratov D.V. , Tchitaykin V.I.
Published: April 2011

At present spent nuclear cores from Alfa class submarines are being stored in temporary facilities, designed to sore them only for a few years (3 to 5 years). This paper assesses the problems of nuclear safety during long-term unplanned forced storage of spent fuel because of the delay in building permanent facilities. The Nuclear Submarines (NS) cores use heavy liquid metal lead-bismuth coolant in the primary circuit of nuclear reactor. The radiation parameters of the discharged cores from NS of the Project 705K (this is the number of ship engineering design) are determined. Based on that determination a step-by-step solution is proposed and the technological and other challenges that the Project faces are considered.
Release of Neptunium, Plutonium, Uranium and Technetium from the Metallic Waste form from the Electrometallurgical Treatment Process
Authors: Johnson S. G. , Noy M. , DiSanto T. , Barber T. L.
Published: April 2011

This waste form is an alloy consisting of stainless steel with 15 wt% zirconium and acts as a host for the immobilization of radioelements that remain with the spent fuel cladding hulls following their treatment using an electrometallurgical treatment process. The results presented here are from 14, 34 and 90-day immersion tests conducted at 90 °C. These tests show that the release of uranium is considerably higher than that of all other major elements present (Fe, Cr, Ni, Zr), but that release of all constituents is comparable to or lower than that for borosilicate glass.
X-ray Absorption Studies of Vanadium Valence and Local Environment in Borosilicate Waste Glasses
Authors: McKeown David A. , Muller Isabelle S. , Matlack Keith S. , Pegg Ian L.
Published: April 2011

XANES and EXAFS data were collected and analyzed to characterize vanadium in borosilicate glasses used for immobilization of sulfur-containing nuclear wastes. Earlier studies suggested that adding vanadium to the melt improves sulfur solubility. Data are presented for a variety of borosilicate glasses, some containing sulfur and some sulfur-free, that have V2O5 concentrations as high as 12 wt%, and for crystalline vanadium sulfide, silicate, and oxide standards. The data for all glasses investigated indicate that most or all vanadium has a +5 valence and is tetrahedrally coordinated by oxygen atoms. Both XANES and EXAFS also show that glasses synthesized under reducing conditions can have pentacoordinated V+4 populations up to approximately 20 to 25% of all vanadium present with the remainder being V+5O4. There is no evidence from XANES or EXAFS of V-S bonds in any of the glasses investigated.
The SR 97 Safety Assessment of a KBS 3 Repository for Spent Nuclear Fuel – Overview, Review Comments and New Developments
Authors: Hedin Allan , Kautsky Ulrik , Morén Lena , Sellin Patrik , Selroos Jan-Olof
Published: April 2011

In preparation for coming site investigations for siting of a deep repository for spent nuclear fuel, the Swedish Nuclear Fuel and Waste Management Company, SKB has carried out the longterm safety assessment SR 97, requested by the Swedish Government. The repository is of the KBS-3 type, where the fuel is placed in isolating copper canisters with a high-strength cast iron insert. The canisters are surrounded by bentonite clay in individual deposition holes at a depth of 500 m in granitic bedrock. Geological data are taken from three sites in Sweden to shed light on different conditions in Swedish granitic bedrock.

The future evolution of the repository system is analysed in the form of five scenarios. The first is a base scenario where the repository is postulated to be built entirely according to specifications and where present-day conditions in the surroundings, including climate, persist. The four other scenarios show the evolution if the repository contains a few initially defective canisters, in the event of climate change, in the event of earthquakes, and in the event of future inadvertent human intrusion.

The principal conclusion of the assessment is that the prospects of building a safe deep repository for spent nuclear fuel in Swedish granitic bedrock are very good. The results of the assessment also serve as a basis for formulating requirements and preferences regarding the bedrock in site investigations, for designing a programme for site investigations, for formulating functional requirements on the repository's barriers, and for prioritisation of research.

SR 97 has been reviewed both by an international group of OECD/NEA experts and by Swedish authorities. The NEA reviewers concluded that “SR 97 provides a sensible illustration of the potential safety of the KBS-3 concept”, and no issues were identified that need to be resolved prior to proceeding to the investigation of potential sites. The authorities' conclusions were in principal consistent with those of the NEA.

Uncertainties and lack of knowledge in different areas identified in SR 97 have strongly influenced the contents and structure of SKBs most recent research programme, RD&DProgramme 2001.

Since SR 97, the methodology for probabilistic consequence analyses have been further developed. Analytic approximations to the numerical transport models used in SR 97 have been developed. The new models have been used to extend the probabilistic calculations in SR 97.
Properties of Plutonium-Containing Colloids Released from Glass-Bonded Sodalite Nuclear Waste form
Authors: Morss Lester R. , Mertz Carol J. , Kropf A. Jeremy , Holly Jennifer L.
Published: April 2011

In glass-bonded sodalite, which is the ceramic waste form (CWF) to immobilize radioactive electrorefiner salt from spent metallic reactor fuel, uranium and plutonium are found as 20-50 nm (U,Pu)O2 particles encapsulated in glass near glass-sodalite phase boundaries. In order to determine whether the (U,Pu)O2 affects the durability of the CWF, and to determine release behavior of uranium and plutonium during CWF corrosion, tests were conducted to measure the release of matrix and radioactive elements from crushed CWF samples into water and the properties of released plutonium. Released colloids have been characterized by sequential filtration of test solutions followed by elemental analysis, dynamic light scattering, transmission electron microscopy (TEM), and X-ray absorption spectroscopy. This paper reports the composition, size, and agglomeration of these colloids. Significant amounts of colloidal, amorphous aluminosilicates and smaller amounts of colloidal crystalline (U,Pu)O2 were identified in test solutions. The normalized releases of uranium and plutonium were significantly less than the normalized releases of matrix elements, i.e., the CWF retains these radionuclides well.
Radioisotope Fractionation and Secular Disequilibrium in Performance Assessment for Geologic Disposal of Nuclear Waste
Authors: Murphy William M. , Pickett David A.
Published: April 2011

Two potential applications of radioisotope fractionation and decay-series secular disequilibrium in performance assessment for geologic repositories for nuclear waste are preferential radionuclide release in source term analysis and characterization of system closure as a measure of the capacity of the geologic system to isolate waste. A primary mechanism of radioisotope fractionation is selective release and mobility of alpha decay products because of nuclear recoil effects, which is evident in natural system data. Preferential release of radioisotopes from nuclear waste forms or solubility limiting solid phases could affect repository performance; however, consequences of differential radioisotope releases are neglected in performance assessments. Decay-series disequilibria are useful also to characterize open/closedsystem behavior in natural systems. Systems that are closed on time scales that are long relative to the half-lives of decay chain nuclides achieve secular equilibrium characterized by unit activity ratios among series nuclides. For geologic disposal of nuclear waste, measures focused on chemical system closure could capture the essential characteristics of the natural system with respect to radionuclide isolation and could be based quantitatively on uranium and thorium decay series secular equilibria/disequilibria.
Comparison with Amino Group and Hydrophilic Group for Protein Afftnity by Excimer Laser Induced Functional Groups Substitution Onto Pet Film
Authors: Omuro Hitoshi , Nakagawa Masato , Fukuda Hiroaki , Murahara Masataka
Published: April 2011

PET has been widely used for medical materials such as an artificial ligament. However, the affinity of tissues is no good. To compensate this, the mesh formed PET has clinically been used for artificial ligament intruding tissue into mesh. However, this method has not shown sufficient affinity with the tissue; that is, the initial adapting strength of the material and tissue is weak. · The artificial ligament must be biocompatible to contact blood and tissue. The foregoing artificial ligament, however, doesn't satisfy the biocompatibility. ·

Thus, we have modified the PET surface into hydrophilic by substituting NH2 or OH functional groups. Firstly, an ArF excimer laser light was irradiated the PET with water on top. The OH functional group was substituted on the PET surface by this photochemical reaction. Secondly, the ArF excimer laser light was irradiated the PET in ammonia gas ambient. In this photochemical reaction, the NH2 functional group was substituted on the PET surface.

· In this study, the untreated sample had the contact angle with water of 80 degrees and the bonding strength with protein of only 1.0kg/cm2. The contact angle of the modified sample improved to 40 degrees and the bonding strength, to 23kg/cm2. When treated in ammonia gas, the contact angle also improved to 40 degrees; however, the bonding strength was almost the same as that of the untreated sample.

It was confirmed that the affinity of the PET for water and protein could be controlled by increasing or decreasing the substitution concentration of OH and NH2 functional groups on the surface.
Application of a Non-equilibrium Green's function method to electrical transport through single molecular-assembled metallic nanoparticles
Authors: Xue Yongqiang , Ratner Mark A.
Published: April 2011

We describe a theory of coulomb blockade of tunneling through molecular-assembled metallic nanoparticles based on the Non-equilibrium Green's function method. We apply the theory to study current transport through a single metallic nanoparticle connected to the leads through two molecular bridges with arbitrary metal-molecule coupling and electron-molecular vibration coupling. We present model calculations of the current-voltage characteristics.
Signal Propagation and Multiplexing Challenges in Electronic Textiles
Authors: Muth J. F. , Grant E. , Luthy K. A. , Mattos L. S. , Braly J. C. , Dhawan A. , Seyam A. M. , Ghosh T. K.
Published: April 2011

Weaving, knitting or placing electronic circuits within a textile matrix offer exciting possibilities for large-scale conformal circuits where the circuit dimensions can be measured on the scale of yards instead of inches. However, compared with conventional printed circuit board circuits, the textile manufacturing process and the electrical/mechanical properties of the fibers used in making the textile place unusual constraints on the electrical performance of textile circuits. In the case of distributed sensors connected via an electronic fabric, signal attenuation and the ability to form reliable interconnections are major challenges. To explore these challenges we have woven and knitted a variety of electrical transmission lines and optical fibers in fabrics to analyze their performance. The formation of interconnects and disconnects between conductors woven in textiles is also discussed, and a passive acoustic array is described as a possible electronic textile application.
Defining Flexibility and Sewability in Conductive Yarns
Authors: Orth Margaret
Published: April 2011

In order for electronic textiles to truly qualify as textiles, they must maintain one of the intrinsic qualities of textiles, flexibility, or the ability to resist permanent deformation under bending, lateral stress and strain. Flexibility will allow electric textiles to be intimate, soft, wearable, conformable and durable. Unfortunately, flexibility is poorly understood by many researchers who come from a traditional electronics background. This paper presents some common terminology of textiles, and different approaches to understanding flexibility in fibers and yarns. Because one of the most mechanically stressful textile manufacturing process is machine sewing and embroidery, this paper defines the necessary properties of machine sewable yarns and demonstrates a formal Curl Test for judging the sewability and flexibility of stainless steel yarns. This paper also examines flexibility in yarns and fibers, historically and based on a mathematical model and more qualitative properties.
An Approach towards the Printing of Polymer Circuits
Authors: Knobloch Alexander , Bernds Adolf , Clemens Wolfgang
Published: April 2011

The combination of soluble polymers with printing and coating techniques enabled the fabrication of polymer field-effect transistors (PFETs) on flexible films. The devices were built in a top gate configuration, with four functional layers deposited. The electrodes were patterned by gravure offset printing, where source-drain were made from conducting polyanilin and carbon black filled conducting ink was used as gate material. The doctor blading technique was utilized for coating low viscosity solutions, where Poly(3-alkyllthiophene) served as active semiconductor material. Thus completely printed PFETs have been demonstrated. Further steps for printing integrated polymer circuits included the fabrication of inverters combined from two printed. Screen-printing could be used as an alternative to coating and has the potential to enable vertical electrical interconnects between top and bottom layer of circuits. To test the suitability insulating layers were screen-printed homogenously onto lithographically patterned electrodes made from gold. The PFETs' yield was sufficient enough to let a 7-stage ring oscillator work with a clock frequency of 4 Hz.
CdSe Nanoparticle/Metal-Organic Inks For Printable Electronics
Authors: Schulz Douglas L.
Published: April 2011

The research objective of this project was the spray deposition of CdSe films using a nanoparticle CdSe suspension as the precursor ink. This ink consisted of CdSe nanoparticles (nano-CdSe) mixed with a “reactive dispersant” in a non-aqueous solvent. The reactive dispersant, a metal-organic molecule, served two purposes; (1) to form a dispersed CdSe suspension at room temperature, and (2) to thermally “unzip” giving CdSe and a byproduct. The CdSe thereby formed could be deposited at the grain boundaries and serve to physically and electrically connect the CdSe nanoparticles at moderate, plastic-compatible temperatures. If electronics-grade CdSe layers could be produced at low deposition temperatures, this approach may be applicable to printed CdSe-based thin film field-effect transistors (TFTs) on flexible substrates.
Nonlinear Carrier Relaxation in a Single GaAs Self-organized Quantum Dot
Authors: Kuroda T. , Sanguinetti S. , Minami F. , Gurioli M. , Watanabe K. , Koguchi N.
Published: April 2011

We resolved a photoemission signal from a single self-organized GaAs/Al0.3Ga0.7As quantum dot (QD) with picosecond time resolution. The emission spectra consisting of the multiexciton structures are observed to depend on the delay time and the excitation intensity. Through the analysis we can determine the carrier relaxation time as a function of population of photoinjected carriers. Enhancement of the intra-dot carrier relaxation is demonstrated to be due to the carrier-carrier scattering inside a single QD.
Influence of In0.2Ga0.8As strain-reducing layer on the active region of quantum dot superluminescent diodes
Authors: Zhang Z. Y. , Li Ch. M. , Jin P. , Meng X. Q. , Xu B. , Ye X. L. , Wang Z. G.
Published: April 2011

We have investigated the optical properties of asymmetric multiple layer stacked self-assembled InAs quantum dot with different interlayer. We found that asymmetric multiple stacked QD samples with In0.2Ga0.8As + GaAs interlayer can afford a 180nm flat spectral width with strong PL intensity compared to other samples at room temperature. We think this result is due to the introduction of In0.2Ga0.8As strain-reducing layer. Additionally, for the broad spectral width and the strong PL intensity, this structure can be a promising candidate for quantum-dot superluminescent diodes.
Optical Properties of InAs/InP Planar Quantum Dot Microcavities
Authors: Dalacu Dan , Poitras Daniel , Lefebvre Jacques , Poole Philip J. , Aers Geoff C. , Williams Robin L.
Published: April 2011

Planar InAs/InP quantum dot microcavities using multi-layer SiO2/Ta2O5 Bragg reflectors have been studied in emission. The spectra exhibit collection optics-limited cavity linewidths of ∼1meV with the occasional ∼200μeV single-dot emission. Measurements as a function of incident power show quantum dot saturation behavior, with transfer of oscillator strength to the wetting layer outside the cavity stop band. Saturation behavior at fixed pump power is also observed as a function of decreasing temperature. Dispersion measurements as a function of emission angle show polarization splitting in qualitative agreement with theory.
Effect Of Phosphorus On Ge/Si(001) Island Formation
Authors: Kamins Theodore I. , Medeiros-Ribeiro Gilberto , Ohlberg Douglas A. A. , Stanley Williams R.
Published: April 2011

When Ge is deposited epitaxially on Si, the strain energy from the lattice mismatch causes the Ge in layers thicker than about four monolayers to form distinctive, three-dimensional islands. The shape of the islands is determined by the energies of the surface facets, facet edges, and interfaces. When phosphorus is added during the deposition, the surface energies change, modifying the island shapes and sizes, as well as the deposition process. When phosphine is introduced to the germane/hydrogen ambient during Ge deposition, the deposition rate decreases because of competitive adsorption. The steady-state deposition rate is not reached for thin layers. The deposited, doped layers contain three different island shapes, as do undoped layers; however, the island size for each shape is smaller for the doped layers than for the corresponding undoped layers. The intermediate-size islands are the most significant; the intermediate-size doped islands are of the same family as the undoped, multifaceted “dome” structures, but are considerably smaller. The largest doped islands appear to be related to the defective “superdomes” discussed for undoped islands. The distribution between the different island shapes depends on the phosphine partial pressure. At higher partial pressures, the smaller structures are absent. Phosphorus appears to act as a mild surfactant, suppressing small islands.
Estimation of Silicon Nanocrystalline Sizes from Photoluminescence Measurements of RF Co-Sputtered Si/SiO2 Films.
Authors: Ramírez-Porras A. , Fonseca L.F. , Resto O.
Published: April 2011

A stochastic distribution of nanocrystalline sizes model is applied to fit photoluminescence (PL) spectra of luminescent Si nanocrystals in a Si/SiO2 matrix synthesized by RF co-sputtering on the top of quartz substrates. With this method, the PL spectra from a diverse set of samples can be resolved mainly as the sum of two components: a contribution from a gaussian-like distribution of sizes of quantum dots (QD) and a similar component from a distribution of quantum wires (QW). These distributions of sizes and their associated PL energies agree well with the so-called Smart Quantum Confinement model (SQC).
Polarization Anisotropy in Electroreflectance Spectrum of Porous Silicon
Authors: Toyama Toshihiko , Nakai Yasuharu , Moriguchi Koji , Okamoto Hiroaki
Published: April 2011

Linearly polarized electroreflectance (ER) measurements have been firstly performed on PSi with near-normal incident (NNI) and glancing-angle incident (GAI) light. In the NNI geometry, no significant polarization anisotropy is observed. Meanwhile, in GAI geometry, a clear polarization anisotropy is observed. The s-polarized ER spectrum consists of the ER features corresponding to those found in the NNI geometry, while in the p-polarized ER spectrum, the two features found in s-polarized spectrum in infrared-visible region are not found, while a new feature is observed at ∼2.1 eV. The mechanism of the unusual polarization anisotropy is discussed in association with structural anisotropy of PSi.
Investigation on Process Dependence of Self-Assembled Metal Nanocrystals
Authors: Lee Chungho , Liu Zengtao , Kan Edwin C.
Published: April 2011

We report the systematic characterization of metal nanocrystal formation on ultra-thin tunnel gate oxide (2∼3nm) for memory applications. To get a high density and small average size of nanocrystals, the process parameters including annealing temperature, initial film thickness, and substrate doping are investigated for Au, Ag, and Pt nanocrystal formation with Si nanocrystal structure as control samples. The observation of nanocrystal formation by scanning electron microscope (SEM) shows that annealing below melting temperature of deposited film contributes to the reshaping of nanocrystals, while the initial film thickness to actual nanocrystal growth. In addition, the Schottky charge effect from substrate doping is not negligible if the tunnel oxide is thin. Controlling the process parameters, Au, Ag, and Pt nanocrystals of 4.0×1011cm-2, 2.8×1011cm-2, and 2.4×1011cm-2 can be formed with mean size of 6.2nm, 6.6nm, and 8.0nm, respectively. The observation of nanocrystals by scanning transmission electron microscope (STEM) shows that nanocrystals are spherical and crystalline. Metal contamination to the Si/SiO2 interface is also closely monitored with many process recipes of metal nanocrystal formation on 2∼3nm oxide showing atomically clean interface. Electrical evaluation of nanocrystal formation is carried out by C-V measurements of metal-oxide-semiconductor (MOS) capacitors with embedded metal nanocrystals.
The Microstructure of Co Nanoparticles Directly Deposited on Si (001) Substrates Using DC Magnetron Sputtering
Authors: Chung Bing-Xian , Liu Chuan-Pu , Chen Jiun-Nan
Published: April 2011

Dispersive cobalt nanoparticles are fabricated directly on Si (001) substrates by DC magnetron sputtering at room temperature. During deposition, the parameters chosen for the investigation are substrate bias (from +525 To –100 Volts), target-to-substrate distance (from 6 to 12 cm) and deposition time (from 10 to 30m sec), while the other parameters are kept the same, including the power of 50 watts. Atomic force microscope (AFM) is employed to determine the density and morphology of cobalt nanoparticles whereas high-resolution electron microscope (HRTEM) is used to visualize the resulting microstructure in the nanoparticles. It is found that Co nanoparticle array can be formed by combining the optimum substrate bias and target-to-substrate distance. The size uniformity of the nanoparticle array can be enhanced by positive bias due to charging effects. The nanoparticle of as small as a few nanometers can be successfully fabricated by DC-sputtering and can be applied to nanotube growth as catalysts.
Construction of Spherical Assembly of Gold Nanoparticles Using Tetra[(methylthio)methyl] silane as Ligand
Authors: Maye Mathew M. , Lim I-Im S. , Luo Jin , Han Li , Rabinovich Daniel , Chen Sandy , Maye Michael P. , Zhong Chuan-Jian
Published: April 2011

This paper reports a study on the assembly of gold nanoparticles via a tetradentate organosulfur ligand, tetra[(methylthio)methyl] silane. We have characterized the evolution of the assembly from individual nanoparticles to spheres (30 ∼ 160 nm) of linked nanoparticles using UV-Visible, TEM, and AFM techniques. We have also demonstrated that the assemblies could be effectively disassembled via manipulating the ligand chemistry. Intriguing assembly-substrate interactions were observed, which could be related to interfacial hydrophobicity. Implications of these findings to the development of abilities in interfacial manipulation of the nanostructures are also discussed.
The Effect of Nanotube Loading and Dispersion on the Three-Dimensional Nanostructure of Carbon Nanotube-Conducting Polymer Composite Films
Authors: Hughes Mark , Chen George Z. , Shaffer Milo S. P. , Fray Derek J. , Windle Alan H.
Published: April 2011

Nanoporous composite films of multi-walled carbon nanotubes (MWNTs) and either polypyrrole (PPy) or poly(3-methylthiophene) (P3MeT) were grown using an electrochemical polymerization technique in which the nanotubes and conducting polymer were deposited simultaneously. The concentration and dispersion of MWNTs in the polymerization electrolyte was found to have a significant effect on the thickness of polymer coated on each MWNT and hence the loading of MWNTs in the films produced. It has been shown that for an increasing concentration of MWNTs in the polymerization electrolyte, the thickness of polymer coated on each MWNT decreases. This relationship made it possible to minimize ionic diffusion distances within the nanoporous MWNT-PPy films produced, reducing their electrical and ionic resistance and increasing their capacitance relative to similarly prepared pure PPy films.
Terahertz-Emitting Silicon-Germanium Devices
Authors: Troeger Ralph T. , Adam Thomas N. , Ray Samit K. , Lv Pengcheng , Lehmann Ulrike , Kolodzey James
Published: April 2011

In this paper we report on far-infrared emission in the 1–12 THz frequency range from strained SiGe structures. Pseudomorphic superlattices were grown by Molecular Beam Epitaxy (MBE) at the relatively low substrate temperature of 400°C to prevent germanium segregation. Layer thicknesses, composition, and crystallinity were confirmed by high-resolution X-ray diffraction. Devices were designed to produce confined hole states with various energy separations. Mesa devices were etched in a reactive-ion etching system and tested for edge emission over a wide range of drive currents using an FTIR spectrometer in step-scan mode. THz emission was observed in pulsed mode at current densities as low as 50 A/cm2 and at temperatures as high as 50 K, using a liquid-helium-cooled silicon bolometer detector with a lock-in amplifier. Emission spectral peaks occurred at 7.9 and 9.36 THz for two different samples, in good agreement with k·p calculations.
Amorphous-Microcrystalline Silicon Films Obtained Using Hydrogen Dilution in a DC Saddle-Field Glow-Discharge
Authors: Allen T. , Milostnaya I. , Yeghikyan D. , Gaspari F. , Kherani N.P. , Kosteski T. , Zukotynski S.
Published: April 2011

Amorphous-microcrystalline Si has been grown with hydrogen dilution using the DC saddle-field glow-discharge deposition technique. The five-electrode saddle-field system allows for independent control of the discharge parameters and of the substrate bias. The film structure was studied using Raman spectroscopy and SEM. We find that the structure of the films depends mainly on hydrogen dilution, substrate bias, electrical conductivity of the substrate, and chamber pressure. The deposition conditions, which promote growth of microcrystals, have been identified. It was found that the local electric field at the substrate surface plays a key role in obtaining microcrystallinity.
Tunnel Currents in the Photo-Field Detectors and the Auger Transistor under Strong Electric Field
Authors: Kalganov Vladimir D. , Mileshkina Nina V. , Ostroumova Elena V. , Rogacheva Ekaterina A.
Published: April 2011

The photo-field emission properties of semiconductors at a very strong electric field together with tunnel electron emission in metal-insulator-semiconductor heterostructures with a tunneltransparent layer of an insulator was studied. It was found that a self-consistent quantum well near the surface of semiconductor emitter tips can change the spectral region of photosensitivity of the radiation semiconductor field emitter detectors, and leads to the significant increase in their photosensitivity [1]. Also the appearance of a self-consistent quantum well near the semiconductor surface is the key factor which allows to use the metal-insulator heterojunction in the development of an Auger transistor based on the Al-SiO2-n-Si structure - the fastest operation semiconductor bipolar transistor [2–4]. Conditions for appearance of a self-consistent quantum well under strong electric field in both the near-surface region of a vacuum semiconductor field-emitter and metal-insulator-semiconductor heterostructures (Auger transistor) were studied also.