bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Technological Tradition of Korean Black Ware and The Indigenous Development of Glaze Technology In Korea During The First Millennium A.D.
Authors: Hooper Jennifer J. , Vandiver Pamela B. 
Published: April 2011

ABSTRACTA collection of 70 black ware shards excavated from 16 kiln sites in South Korea and dating from the 3rd-13th centuries were studied using optical microscopy, scanning electron microscopy, and electron beam microprobe analysis to determine the range of technological variability in composition, microstructure and firing temperature. Materials analysis provided a means of deconstructing and reconstructing the development of (1) consistent high temperature firing, (2) unintentional ash glazing on black ware, (3) intentionally applied black glazes, (4) the relationship of grey and black glazes to green and white ones. This paper addresses issues of the influence of high-firing technology on glaze development and the development and continuity of the black glaze tradition. In addition, the black glazed Onggi ware of the late 19th century was compared to the earlier black-glaze tradition, once stabilized in composition in the Koryo dynasty, and results suggest a technological connection with the earlier tradition.
Textile-Clay Laminates: a new-found craft technology from ancient Mesoamerica
Authors: Beaubien Harriet F. , Kaplan Emily , Shah Monica 
Published: April 2011

ABSTRACTTwo Maya-period sites, Las Pacayas and Aguateca, have recently yielded fragments composed of a previously unknown material -- a laminate formed from multiple layers of woven cloth and clay slip. On-site and laboratory conservation efforts enabled the Aguateca finds to be identified as ceremonial headdress elements. Materials analysis and replication experimentation have elucidated technological aspects of this medium, and demonstrate its suitability for fabricating elaborate, lightweight items such as these.
Thin-Film Aerogel Porosity and Stiffness Characterized by Surface Acoustic Wave Spectroscopy
Authors: Flannery C.M. , Murray C. , Baklanov M.R. , Streiter I. , Schulz S.E. 
Published: April 2011

ABSTRACTDensity/porosity and stiffness are the most critical parameters determining properties of porous films, however they are difficult to measure. Here we report characterization of density/porosity and Young's modulus values of a range of nanoporous silica aerogel films via dispersion of laser-generated wideband surface acoustic waves. Results are compared to dielectric constant, Rutherford Backscattering Spectrometry (RBS), Ellipsometric Porosimetry (EP) and Nanoindentation (NI). RBS density correlates well to SAW. EP and NI also show a correlation, however the absolute values do not match. Low Young's modulus values show that the film stiffness is drastically reduced with increasing porosity. The technique is rapid, nondestructive and relatively inexpensive, and yields absolute values of nanoporous aerogel elastic properties which are useful for process control and are difficult to access with other techniques.
Molecular Structure of Interphases Formed by Plasma Polymerized Acetylene Films and Steel Substrates
Authors: Rosales P. I. , Krusling E. J. , Boerio F. J. , Dillingham R. G. 
Published: April 2011

ABSTRACTThe goal of this research was to determine the molecular structure of interfaces between plasma polymerized acetylene films and steel substrates and to elucidate the mechanisms by which the films adhere to the substrates. Inductively-coupled, RF-powered plasma reactors interfaced to an FTIR spectrometer and to an XPS spectrometer were used to deposit films ranging in thickness from a few tens of nanometers to approximately one nanometer onto polished steel substrates. As the thickness of the films was decreased, features in the XPS and FTIR spectra that were characteristic of the bulk of the films decreased in intensity and features characteristic of the interface increased in intensity. A band was observed near 1706 cm−1 in FTIR spectra of the thickest films and attributed to carbonyl groups. Bands were observed near 1600 and 1045 cm−1 in spectra of the thinnest films and attributed to iron carboxylate and iron alkoxide groups that were responsible for adhesion of the films to the substrates. Oxygen required to form these groups was available from water or oxygen molecules adsorbed onto the walls of the reactor.
Influence of Metal Electrodes on the Ferroelectric Responses of Poly(vinylidene fluoride-trifluoroethylene) Copolymer Thin Films
Authors: Xia Feng , Zhang Q. M. 
Published: April 2011

ABSTRACTFerroelectric polymer thin films have been investigated for applications such as sensors, MEMS, and memory devices, just name a few. In these thin film devices, it is anticipated that the interface effect will play an important role in determining the device performance. In this paper, we present the results of a recent study on the influence of metal electrodes on ferroelectric switching behavior of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) polymer thin films. The results show that the influence of metal electrodes on the polarization response can be divided into two effects, the bulk effect and interface effect. The bulk effect manifests itself as the built-in bias field when metal electrodes with different work functions were used on the two surfaces of the P(VDF-TrFE) film. The interface effect is more complicated but is directly related to the metal work function. For a metal I/insulator (ferroelectric film)/metal II (MIM) sandwich structure in which the metal I and metal II possess different work functions, the low frequency polarization hysteresis loop shows asymmetric response (different switching fields). The polarization switching time also depends on whether the applied voltage is in parallel or anti-parallel to the built-in bias field. In the fast polarization switching process, it was observed that the interface effect plays a dominating role and the switching time is mainly limited by the charge injection from metal electrodes to the polymer film. For metal electrodes with higher work function, higher injection currents and hence faster polarization switching were observed. The results from I-V studies also show that the charge injection process is a Schottky type and the barrier height estimated from the temperature dependence of the I-V curves is consistent with the metal work functions used.
Organic / Inorganic Hybrid Material for Coating on Metals
Authors: Tang Zhexiong , Alvarez Neil , Yang Sze 
Published: April 2011

ABSTRACTIn this paper, we present the syntheses of nano particles of organic / inorganic hybrid for coating on metal or glass surfaces. The organic component is a π-conjugated polymer, polyaniline. The inorganic component is a metal oxide, e.g., cerium oxide. Since the organic component is a water-dispersible polymeric complex of polyaniline and poly(acrylic acid), the hybrid particles are also dispersed in water. The synthesis of the organic / inorganic composite is described. The water dispersible hybrid material was coated on aluminum and glass substrates using a molecular layer-by-layer coating process.
Atomic and Electronic Structures of Nano-Interface In Au/TiO2 Catalyst - Electron Microscopic Approach -
Authors: Ichikawa S. , Okazaki K. , Akita T. , Okumura M. , Tanaka K. , Kohyama M. 
Published: April 2011

ABSTRACTThe size dependence of the catalytic property of the gold catalysts has been reported. It is especially interesting that the catalytic property of gold suddenly changes to show a platinum-like behavior when the mean size of gold is below 2nm. This phenomenon should be owing to the change of the electronic structure of the gold, however its detail has not been cleared yet. We investigated the size dependence of the mean inner potential of gold catalysts supported on TiO2, which is affected by the outer valence electron, using electron holography and high-resolution electron microscopy. We found the following tendency. When the size of the gold particle is over 5nm, the values of the mean inner potential are the same level as the reported experimental values of the bulk gold (21–23V) and the calculated values of the bulk gold (25–30V). When the size is below 5nm, the mean inner potential begins to increase over 30V, and it begins to increase suddenly over 40V at the size below about 2nm. It indicates that the electronic structure of the gold particles varies from that of the bulk state as the size of the gold particles reduces. Due to the size reduction, the volume fraction of the surface atoms and the interface atoms increases, e.g., almost half of the atoms locate on the surfaces or at the interface in case of the top half of the octahedron particle with the size 1.6nm. The surface dipole and the interface dipole should be formed owing to the electron out of the surface to the vacuum and the local charge transfer from the gold particles to the TiO2 surface. These dipole effects might be effective and one of the reasons for the increase of the mean inner potential of gold particles.
Substrate Dependence of Surface Plasmon Resonance Frequency of Silver Island Films
Authors: Xu Gang , Tazawa Masato , Jin Ping 
Published: April 2011

ABSTRACTA simple method was demonstrated to tune surface plasmon resonance wavelength of silver island films by introducing an underlayer. The tunability can be much enhanced by varying the underlayer medium. In combination with the size effects of metallic islands the plasmon wavelength can be readily adjusted throughout the visible spectral regions. The experimental results were interpreted based on a generalized Maxwell-Garnett theory.
Dual-probe scanning tunneling microscope and a carbon nanotube ring transistor
Authors: Shigematsu Taishi , Watanabe Hiroyuki , Manabe Chikara , Shimotani Kei , Shimizu Masaaki 
Published: April 2011

ABSTRACTFor measuring molecular device, we developed a dual-probe scanning tunneling microscope (D-STM) composed of two STM systems in which a carbon nanotube (NT) was used for STM tip. Using D-STM, we fabricated a NT ring device. The NT ring device showed a switching behavior with applying gate bias. Furthermore, in STM imaging for various gate biases, we could observe directly hole injection into the NT ring.
STM-REBIC study of nanocrystalline and crystalline silicon.
Authors: Nogales E. , Méndez B. , Piqueras J. , Plugaru R. 
Published: April 2011

ABSTRACTElectrically active regions of nanocrystalline silicon (nc-Si) films as well as of a p-type crystalline silicon (c-Si) wafer have been investigated by using a scanning electron microscope/scanning tunneling microscope (SEM/STM) combined instrument. The nc-Si films were obtained by boron implantation of amorphous silicon layers with an average nanocrystal size of about 10 nm. STM current constant images reveal a cell structure in the nc-Si films which was also revealed in the STM remote electron beam induced current (REBIC) images with a resolution of up to 20 nm. The contrast in the STM-REBIC images indicate the existence of space charge regions at the boundaries. The influence of the thermal treatment on the cell structure was studied. For comparison, SEM-REBIC and STM-REBIC images from c-Si wafer were obtained.
Modeling Self-Assembly of Nanoparticle Structures: Simulation of Nanoparticle Chemical Potentials in Polymer-Nanoparticle Mixtures
Authors: Marla Krishna T. , Meredith James C. 
Published: April 2011

ABSTRACTThe expanded ensemble Monte Carlo (EEMC) simulation method has been applied to calculation of the chemical potential of nanocolloidal particles in the presence of polymeric surface modifiers. Two general classes of surface modifiers have been studied – nonadsorbing and freely-adsorbing. For both systems, the infinite dilution colloid chemical potential was calculated as a function of the colloid diameter and the modifier chain length. The colloid chemical potential was found to decrease with increasing modifier chain length for both types of modifiers, albeit for different reasons. Empirical power-law scaling relationships were found to represent the simulation results well. A physical interpretation was proposed for the power law exponents obtained in the case of adsorbing modifiers.
Dynamic Tuning of Optical Waveguides with Electrowetting Pumps
Authors: Cattaneo Francesco , Mach Peter , Hsieh Jennifer , Krupenkin Tom , Yang Shu , Rogers John A. 
Published: April 2011

ABSTRACTThis paper reviews some of our recent work on a new class of photonic component that uses electrowetting pumps and microfluidic channels for dynamic tuning of the characteristics of optical waveguides. These pumps exploit the ability to alter the contact angle of conductive liquids situated on top of a dielectric layer with appropriately patterned underlying electrodes. By applying different voltages to opposite sides of a conductive fluid plug, the contact angle imbalance created between the ends of the liquid drives fluid motion toward the higher field regions [1]. In our design, this electrically controlled, fully reversible motion of fluids contained within recirculating channels is used to alter the effective indices of waveguide modes of three different types of optical fiber structures: fiber Bragg and long period gratings and etched or tapered fiber. Our systems operate non-mechanically and have excellent optical performance, including low insertion and polarization-dependent losses. These characteristics suggest a promising potential for electrowetting-based microfluidic tuning of optical fiber devices and other photonic components.
Microreactors for Thin-Film Calorimetry
Authors: Rodríguez-Viejo J. , Chacón M. , Lopeandía A.F. , Clavaguera-Mora M.T. , Arana Leonel R. , Jensen K.F. 
Published: April 2011

ABSTRACTWe have designed and developed a calorimeter that is capable of measuring the heat released by ultrathin films in the temperature range from 77 to 1050 K. Semiconductor processing techniques are used to fabricate the microreactors. The symmetric design of the Pt heaters in the microreactor channel provide a good temperature profile across the active region of the membrane making it suitable for accurate calorimetric measurements. The low thermal mass of our system allows for a high sensitivity. The effective heat capacity of the microcalorimeters with a 200 nm SixNy membrane is 0.14 μJ/K at room temperature. In high vacuum heating rates of 2×106 K/s have been achieved. Under these conditions the microcalorimeter works as an adiabatic scanning calorimeter and therefore heat capacity is directly obtained from the input power. A thermal characterization of the microcalorimeters in the transient state and calorimetric measurements on indium thin films and films made of CdSe nanocrystals are briefly discussed to show the potentiality of the microreactors.
Growth of Polycrystalline Silicon Carbide on Thin Polysilicon Sacrificial Layers for Surface Micromachining Applications
Authors: Wiser R.F. , Chung J. , Mehregany M. , Zorman C.A. 
Published: April 2011

ABSTRACTPolycrystalline silicon carbide (poly-SiC) films were deposited by atmospheric pressure chemical vapor deposition (APCVD) at epitaxial growth temperatures on planar, 100 nm-thick polysilicon sacrificial layers using two recipes that included or excluded a pre-growth carbonization step. Poly-SiC films grown using the carbonization-based recipe exhibited a relatively high degree of (111) 3C-SiC texture and had uniform, well-defined, void-free poly-SiC/polysilicon interfaces. In contrast, poly-SiC films grown without carbonization were randomly oriented, had numerous poly-SiC inclusions that sometimes completely penetrated the polysilicon underlayer, and had a higher surface roughness than the films grown with carbonization. Analysis of micromechanical clamped-clamped (C-C) beam resonators fabricated from films grown using the two differing recipes shows that the carbonization step is needed to protect the thin polysilicon sacrificial layer from voids and inclusions and thus maintain the proper spacing between the drive electrodes and the resonant beams.
Fabrication of Micro-Relief Structures in Thick Resist for Anti-Counterfeiting Applications
Authors: Leech Patrick W. , Zeidler Henning 
Published: April 2011

ABSTRACTMicro-relief surfaces including grating structures, greytone/micrographic features and microramps have been fabricated with depth features of up to 30 μm. Grey scale lithography has been used to produce the microstructures by a single UV exposure into a layer of thick resist. Arrays of the pixelated microstructures have formed the security features on the surface of optically variable devices. Each of the microstructures was designed to provide an intended optical effect in features such as portraits, symbols and lettering which comprised a larger image (typically 2.5 × 3 cm). An essential part of the process has been the determination of the optimum conditions for coating of the thick resist (AZ P4620) as a function of spin speed and exposure.
Fabrication Of Flat RF MEMS Switch Membrane By Minimizing Of Stress Gradients In The Au Membrane Structure
Authors: Kim Jong-Seok , Song Hoon , Cho Jin Woo , Lee Eun Sung , Park Sun Hee , Lee Mun Chul , Shim Dong Hwa , Song In Sang , Kim Jung Woo , Kang Seok Jin , Song Ki Moo 
Published: April 2011

ABSTRACTRF MEMS(Micro-Electro-Mechanical-System) switch technology is one of powerful solution for future RF systems. This technology provides low insertion loss, High linearity and broad bandwidth. Wide driving membrane used MEMS switch can reduce driving voltage but it is easy to bend because of the stress gradient. In order to solve this problem we fabricated Au cantilever in various sputtering condition and various substrate materials. As a result of this experiment, we fabricated cantilever which was bent within 1 um, with 2 um thickness and 340 um length. We applied this condition to RF MEMS switch and we fabricated switch membrane within 1 um bend, under 10MPa stress gradient.
Modeling of a Rotaxane-based Molecular Device
Authors: Zheng Xiange , Sohlberg Karl 
Published: April 2011

ABSTRACTA computational procedure is presented for investigating photo-induced switchable rotaxanes and demonstrated for a known system. This procedure starts with the generation of more than 104 chemically reasonable rotaxane conformations based on an empirical intramolecular potential energy function. Single-point energy calculations at the semi-empirical (AM1) level are carried out for each structure in the singlet (ground), triplet, and anionic doublet states. The structural features are assigned and then correlated with energy for each state. What emerges is a profile of the structure-energy relationship that captures the salient features of the system that endow it with device-like character. Full geometry optimization of a subset of co-conformations (∼1%) demonstrates that the procedure based on single-point calculations is sufficient to obtain a profile of the relationship of structural features to energy that is consistent with experiments, at greatly reduced computational cost.
Semi-Empirical Study of a pH-Switchable [2] Rotaxane
Authors: Frankfort Laura , Sohlberg Karl 
Published: April 2011

ABSTRACTSemi-empirical (AM1) electronic structure calculations are reported on a pH-switchable [2] rotaxane whose synthesis was reported in [Angew. Chem. Int. Ed., 36 (1997) 1904]. The [2] rotaxane possesses two cationic binding sites, with different affinities toward dibenzo [24] crown-8 (the ring component of the [2] rotaxane) depending upon the pH of the system. The computational results capture this pH-sensitive bistability, the key device-like characteristic of the rotaxane.
Epitaxial Growth and Characterization of 4H-SiC(11–20) and (03–38)
Authors: Kimoto T. , Hashimoto K. , Fujihira K. , Danno K. , Nakamura S. , Negoro Y. , Matsunami H. 
Published: April 2011

ABSTRACTHomoepitaxial growth, impurity doping, and diode fabrication on 4H-SiC(11–20) and (03–38) have been investigated. Although the efficiency of nitrogen incorporation is higher on the non-standard faces than on (0001), a low background doping concentration of 2∼3×1014 cm-3 can be achieved. On these faces, boron and aluminum are less effectively incorporated, compared to the growth on off-axis (0001). 4H-SiC(11–20) epilayers are micropipe-free, as expected. More interestingly, almost perfect micropipe closing has been realized in 4H-SiC (03–38) epitaxial growth. Ni/4H-SiC(11–20) and (03–38) Schottky barrier diodes showed promising characteritics of 3.36 kV-24 mΩcm2 and 3.28 kV–22 mΩcm2, respectively. The breakdown voltage of 4H-SiC(03–38) Schottky barrier diodes was significantly improved from 1 kV to above 2.5 kV by micropipe closing.
Effect of Pressure on the energy band gaps of InxGa1-xN and InxAl1-xN
Authors: Dridi Z. , Bouhafs B. , Ruterana P. 
Published: April 2011

ABSTRACTUsing a first-principles method, we study the effect of pressure on the band gap energies of wurtzite InxGa1-xN, and InxAl1-xN. The fundamental band gap energies are direct and increase rapidly with pressure. The pressure coefficients vary in the range of 19.8–24.8 meV/GPa for InxGa1-xN, and 16.7–20.7 meV/GPa for InxAl1-xN; they depend on alloy composition with a strong deviation from linearity. The band gap bowing of the InGaN increases continuously with pressure while those of InAlN strongly decreases at p=14 GPa.
Searching for the Influence of the Sapphire Nitridation Conditions on GaN Films Grown by Cyclic PLD
Authors: Sanguino P. , Niehus M. , Koynov S. , Melo L. , Schwarz R. , Soares M. J. , Boemare C. , Monteiro T. 
Published: April 2011

AbstractWe have deposited highly c-axis oriented GaN films on sapphire by the Cyclic Pulsed Laser Deposition Technique. Nitridation of the sapphire substrates for these samples was performed at 200 °C, 400 °C and 600 °C. For that purposed, we used a radio frequency nitrogen plasma during four hours. The films were compared in terms of crystal structure, surface morphology and optical quality. Although small, the biggest differences were detected in the surface morphology of the films. Additionally, a typical GaN sample nitridated at 200 °C was analysed by photoluminescence and showed the typical donor bound excitonic luminescence (D0X ) transition at 3.47 eV and a line near 3.42 eV. These lines show a FWHM of 20 meV and 30 meV at 13K, respectively.
Effect of Thickness Variation in High-Efficiency Ingan/Gan Light Emitting Diodes
Authors: Narayan J. , Wang H. , Ye Jinlin , Hon Schang-Jing , Fox Kenneth , Chen Jyh Chia , Choi H. K. , Fan John C.C. 
Published: April 2011

ABSTRACTWe have found that InxGa(1-x)N/GaN multi-quantum-well (MQW) light emitting diodes (LEDs) having periodic thickness variation (TV) in InxGa(1-x)N active layers exhibit substantially higher optical efficiency than LEDs with uniform InxGa(1-x)N layers. In these nano-structured LEDs, the thickness variation of the active layers is shown to be more important than In composition fluctuation in quantum confinement of excitons (carriers). Detailed STEM-Z contrast analysis, where image contrast is proportional to Z2(atomic number)2, was carried out to investigate the thickness variation as well as the spatial distribution of In. In the nanostructured LEDs, there are short-range (SR-TV, 3 to 4 nm) and long-range thickness variations (LR-TV, 50 to 100 nm) in InxGa(1-x)N layers. It is envisaged that LR-TV is the key to quantum confinement of the carriers and enhancing the optical efficiency. We propose that the LR-TV thickness variation is caused by two-dimensional strain in the InxGa(1-x)N layer below its critical thickness. The SR-TV may be caused by In composition fluctuation. The observations on thickness variation are in good agreement with model calculations based upon strain effects.