bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lattice-Gas-Decomposition Model for Vacancy Formation Correlated with B2 Atomic Ordering in Intermetallics
Authors: Biborski A. , Zosiak L. , Kozubski R. , Pierron-Bohnes V. 
Published: February 2009

AbstractThermal vacancy formation correlated with atomic ordering was modelled in B2-ordering A-B binary intermetallics. Ising Hamiltonian was implemented with a specific thermodynamic formalism for thermal vacancy formation based on the phase equilibria in a lattice gas composed of atoms and vacancies. Extensive calculations within the Bragg-Williams approximation [1] were followed by Semi-Grand Canonical Monte Carlo (SGCMC) simulations. It has been demonstrated that for the atomic pair-interaction energies favouring vacancy formation on A-atom sublattice, equilibrium concentrations of vacancies and antisite defects result mutually proportional in well defined temperature ranges. The effect observed both in stoichiometric and non-stoichiometric (both A-rich and B-rich) binary alloys was interpreted as a tendency for triple defect formation. In B-rich alloys vacancy concentration did not extrapolate to zero at 0 K, which indicated the formation of constitutional vacancies. Energetic conditions for the occurrence of the effects were analysed in detail. The modelled temperature dependence of vacancy concentration in the B2-ordering A-B binaries with triple defects will be included in the Kinetic Monte Carlo (KMC) simulations of chemical ordering kinetics in these systems with reference to the experimental results obtained for NiAl [2].
Formation of Wrinkle Patterns on Porous Elastomeric Membrane and Their Fabrication of Hierarchical Architectures
Authors: Cui Yue , Yang Shu 
Published: February 2009

AbstractWe report the formation of wrinkle patterns on porous elastomeric membrane and their fabrication of hierarchical architectures through mechanical stretching and replica molding. The technique builds upon a buckling instability of a stiff layer supported by a porous elastomeric membrane which was induced by surface plasma oxidation of the pre-stretched porous elastomer followed by removal of the applied mechanical strain to form wrinkle patterns, and replica molding of the deformed features on the porous membrane into epoxy to form hierarchical architectures through casting the UV-curable epoxy prepolymer and UV curing. We find that due to the existence of micropores on the membrane, the formation of wrinkle patterns is different from that formed on a continuous elastomeric film, and by varying the applied mechanical stretching strain condition and plasma oxidation condition, the wrinkle patterns could be either confined by the micropores on the membrane to exhibit a wavelength equal to its pitch or form wrinkles with much large wavelength compared with that formed on a continuous elastomeric film. Therefore, the micropillar arrays fabricated by replica molding could stand on different types of wrinkle patterns to form different hierarchical architectures. The method we illustrate here offers a simple and cost-effective approach to fabricate various hierarchical structures, and provides possibilities for potential applications in various fields, such as microfluidics, micro- and nanofabrication of complex structures, crystal formation, cell attachment, superhydrophobicity and dry adhesion.
Cellulose Electroactive Paper (EAPap): The Potential for a Novel Electronic Material
Authors: Kim Joo-Hyung , Kang Kwangsun , Yun Sungryul , Yang Sangyeul , Lee Min-Hee , Kim Jung-Hwan , Kim Jaehwan 
Published: February 2009

AbstractCellulose electro-active paper (EAPap) has attracted much attention as a new smart electronic material to be utilized as mechanical sensors, bio compatible applications and wireless communications. The thin EAPap film has many advantages such as lightweight, flexible, dryness, biodegradable, easy to chemically modify, cheap and abundance. Also EAPap film has a good reversibility for mechanical performance, such as bending movement, under electric field. The main actuation mechanism governed by piezoelectric property can be modulated by material direction and stretching ratio during process. In this paper we present the overview as well as fabrication process of cellulose EAPap as a novel smart material. Also we propose the method to enhance the piezoelectricity, its mechanical and electromechanical properties. In addition, the fabrication of high quality metal patterns with Schottky diode on the cellulose surface is an initiating stage for the integration of the EAPap actuator and electronic components. The integration of flexible actuator and electronic elements has huge potential application including flying magic carpets, microwave driven flying insets and micro-robots and smart wall papers.
Shape Memory Actuation by Resistive Heating in Polyurethane Composites of Carbonaceous Conductive Fillers
Authors: Gunes I. Sedat , Jimenez Guillermo A , Jana Sadhan C 
Published: February 2009

AbstractThe dependence of electrical resistivity on specimen temperature and imposed tensile strains was determined for shape memory polyurethane (SMPU) composites of carbon nanofiber (CNF), oxidized carbon nanofiber (ox-CNF), and carbon black (CB). The SMPU composites with crystalline soft segments were synthesized from diphenylmethane diisocyanate, 1,4-butanediol, and poly(caprolactone)diol in a low-shear chaotic mixer and in an internal mixer. The materials synthesized in the chaotic mixer showed higher soft segment crystallinity and lower electrical percolation thresholds. The soft segment crystallinity reduced in the presence of CNF and ox-CNF; although the reduction was lower in the case of ox-CNF. The composites of CB showed pronounced positive temperature coefficient (PTC) effects which in turn showed a close relationship with non-linear thermal expansion behavior. The composites of CNF and ox-CNF did not exhibit PTC effects due to low levels of soft segment crystallinity. The resistivity of composites of CNF and ox-CNF showed weak dependence on strain, while that of composites of CB increased by several orders of magnitude with imposed tensile strain. A corollary of this study was that a high level of crystallinity may cause a PTC effect and prevent any actuation through resistive heating. However, a carefully tailored compound which has reduced crystallinity and which requires minimum amount of filler may prevent PTC phenomenon and could supply necessary electrical conductivity over the operating temperature range, while offering enough soft segment crystallinity and rubberlike properties for excellent shape memory function.
Knowledge-based Approach to Gas Sorption in Glassy Polymers by Combining Experimental and Molecular Simulation Techniques
Authors: Heuchel Matthias , Hölck Ole , Böhning Martin , Siegert Martin R. , Hofmann Dieter 
Published: February 2009

AbstractWe present a method which allows to calculate gas sorption in complex polymers where, as slow processes, gas induced plasticization and volume dilation are important factors. Since the relaxational swelling of the polymer matrix that is observed at elevated gas concentrations takes hours or days, the swelling process is orders of magnitudes too slow to simulate the respective molecular dynamics in reasonable time and effort. To address this apparent incompatibility of experiment and simulation, we use single representative reference states from experiment and construct atomistic packing models according to these specifications. Gas sorption of CO2 and CH4 was successfully calculated on polysulfone, a 6FDA-polyimide, and a polymer of intrinsic microporosity, PIM-1, at 308 K and pressures up to 50 bar.
Silicides for Infrared Surface Plasmon Resonance Biosensors
Authors: Cleary Justin , Peale Robert , Shelton David , Boreman Glenn , Soref Richard , Buchwald Walter 
Published: February 2009

Abstract
Pt-, Pd-, Ni-, and Ti-silicide films on silicon were evaluated as conducting hosts for surface plasmon polaritons (SPP) in proposed long-wave IR (LWIR) attenuated total reflection biosensors. Original LWIR complex permittivity data was collected, from which SPP properties were determined and compared with those for noble metals. LWIR SPPs on silicide films were found to offer enhanced sensitivity to thinner biological entities than when usual metal films are used.
Application of a Chemically Adsorbed Monolayer and Polypyrrole Thin Film for Increasing the Adhesion Force between the Resin Substrate and the Plated Copper Layer
Authors: Ohkubo Yuji , Onishi Shogo , Miyazawa Satoshi , Soejima Kazuhiro , Ogawa Kazufumi 
Published: February 2009

AbstractA chemically adsorbed monolayer containing pyrrolyl group (Pyrrolyl-CAM) was prepared between a plated copper layer and a resin substrate for increasing the adhesion force without roughening a surface of the resin substrate. Although it was not enough to increase the adhesion force between the resin substrate and the copper layer by using only Pyrrolyl-CAM, the sufficient adhesion force was obtained by preparing a polypyrrole thin film between Pyrrolyl-CAM and the copper layer.Pyrrolyl-CAM and the polypyrrole thin film on the substrate were evaluated by an automat-ic contact angle meter and auger electron spectroscopy in order to analyze the condition of the films between the resin substrate and the copper layer.The peel strength test was carried out in order to evaluate the adhesion force. The best ad-hesion force was 0.98 [N/mm], and the target value of 0.60 [N/mm] was sufficiently achieved.
Synthesis of Poly(Methylmethacrylate) Latex with Enhanced Rigidity through Surfactant Control
Authors: Wu Alex , Cho Kwun Lun , Liaw Irving Ian , Zhang Hua , Lamb Robert 
Published: February 2009

AbstractWater-based polymer latexes have attracted much attention since their invention in the early 1950s. Its advantages for both general health and the environment were recognized as they emit far less volatile organic compounds (VOCs) than their solvent-based counterparts.The performance of latex paints and coatings is directly proportional to the ease of particle deformation. This is the main driving force for the paints and coatings industry to focus its research efforts towards understanding its mechanism.In contrast, little has been published with respect to enhancing latex's resistance against deformation despite such needs in applications such as templating porous ceramics for catalysis and biomaterial engineering. Specifically, the latex's resistance to deformation is crucial to retain a network of uniform pores for applications relating to enzyme immobilization and materials reinforcement.The current study reports increased heat-resistance observed in latexes when synthesized using a rigid surfactant, dimethyl siloxane – ethylene oxide block copolymer (PDMS-PEO). The film formation process for this latex was deduced using atomic force microscopy and subsequent roughness analysis. A comparative study using a non-ionic long-chain hydrocarbon surfactant, morpholine oleate, was also conducted.
Preparation of Macroporous Poly(divinylbenzene) Gels via Living Radical Polymerization
Authors: Hasegawa Joji , Kanamori Kazuyoshi , Nakanishi Kazuki , Hanada Teiichi , Yamago Shigeru 
Published: February 2009

AbstractMacroporous cross-linked polymeric dried gels have been obtained by inducing phase separation in a homogeneous poly(divinylbenzene) (PDVB) network formed by organotellurium-mediated living radical polymerization (TERP). The living polymerization reaction of DVB with the coexistence of a non-reactive polymeric agent, poly(dimethylsiloxane) (PDMS), in solvent 1,3,5-trimethylbenzene (TMB) resulted in polymerization-induced phase separation (spinodal decomposition), and the transient structure of spinodal decomposition has been frozen by gelation. Well-defined macroporous monolithic dried gels with bicontinuous structure in the micrometer scale are obtained after removing PDMS and TMB by simple washing and drying. The properties of the macropores have been controlled by changing starting composition.
Multi-Scale Grafted Polymeric Nanostructures Patterned Bottom-Up by Colloidal Lithography and Initiated Chemical Vapor Deposition (iCVD)
Authors: Trujillo Nathan J. , Baxamusa Salmaan H. , Gleason Karen K. 
Published: February 2009

AbstractColloidal lithography is a popular, non-conventional process that uses two–dimensional self-assembled monolayer arrays of colloidal nanoparticles as masks for techniques such as etching or sputtering. Initiated Chemical Vapor Deposition (iCVD) is a surface controlled process which offers unprecedented opportunity for producing polymeric layers grafted to substrates with dangling vinyl bonds and patterned through a colloidal template. We demonstrate a generic “bottom-up” process as an inexpensive and simple technique for creating well-ordered arrays of functional patterned polymeric nanostructures. These patterns were produced from thin polymer films of p(butyl acrylate) and p(hydroxyethyl methacrylate), and are robustly tethered to the underlying substrate, as demonstrated by their ability to withstand aggressive solvents. Furthermore, using capillary force lithography, we created topographical templates for large-scale orientation of the nanoparticle assembly. Through this “top-down” approach, for assisting the bottom-up assembly, we present a process for multi-scale patterning of functional polymeric materials, without the need for expensive lithography tools.
Synthesis of Thermoresponsive Copolymers Composed of Poly(ethylene oxide) and Poly(N-isopropylacrylamide) for Cell Encapsulation
Authors: Trongsatitkul Tatiya , Budhlall Bridgette 
Published: February 2009

AbstractThermoresponsive copolymers of poly(N- isopropyl acrylamide) (PNIPAm) and poly(acrylamide) microgels grafted with poly(ethylene glycol)(PEG) chains were synthesized by free-radical photopolymerization. Poly(ethylene glycol) methyl ether methacrylate (PEGMA) macromonomers with varying number-average molecular weights were used (Mn = 300 and 1,000 g/mol). A simple microarray technique coupled with a laser scanning confocal microscope (LSCM) was used to visualize the effect of temperature on the volume phase transition temperatures of the microgels. In general, increasing the concentration of PEGMA in the PNIPAm-co-Am-co-PEGMA copolymers resulted in a broader and higher lower critical solution temperature (LCST) compared to the PNIPAm microgels. We demonstrated that the PEGMA molecular weight and concentration influenced whether it was incorporated as a grafted copolymer or random copolymer in the PNIPAm microgel. The evidence for this is the shift in the LCST as determined by temperature and differential scanning calorimetry (DSC) measurements. This behavior suggests that incorporation of PEGMA in the copolymer depends on its hydrophilicity or water-solubility which in turn influenced the degree at which the copolymer chains collapsed from a coil-to-globule (volume phase transition) with increasing temperature.
A Novel Gap Narrowing Process for Creating High Aspect Ratio Transduction Gaps for MEM HF Resonators
Authors: Stoffels Steve , Bryce George , Van Hoof Rita , Du Bois Bert , Mertens Robert , Puers Robert , Tilmans Harrie A.C. , Witvrouw Ann 
Published: February 2009

AbstractIn this work a novel technique to create nanometer sized air gaps for high frequency (HF) mechanical resonators will be presented. The technique is based on the narrowing of initially wide gaps with a conformal “narrowing” layer. The novelty of this technique is that it enables the creation of narrow high-aspect ratio gaps (e.g. 100nm gaps in 10μm thick layers) without the need for complex lithography or high aspect ratio etching. Furthermore, the electrodes and the resonator itself can be patterned in a single processing step. The process methodology will be explained and validation experiments in a silicon-germanium (SiGe) based technology will be shown. This technology uses low temperature (∼450°C) poly silicon-germanium (SiGe) as the structural layer, which can be processed above CMOS, and therefore allows the fabrication of MEM devices above CMOS.
Dicing of Fragile MEMS Structures
Authors: Lange Peter , Marenco Norman , Gruenzig Sven , Warnat Stephan , Semperowitsch Thilo 
Published: February 2009

AbstractStealth dicing appears to be the appropriate methode to singulate surface sensitive microelectromechanical devices, without producing dicing debris or using water jet. The operating mode of the stealth dicing will be explained. A three dimensional integration project with open micromachined structures is taken as a reference to evaluate the advantages and limitations of this new dicing method. The preconditions for successful singulations will be discussed. Optical and SEM inspection results after successful separation will be discussed.
Active Field Effect Capacitive Sensors for High-throughput, Label-free Nucleic Acid Analysis
Authors: Sebastian Mannoor Manu , James Teena , Ivanov Dentcho V. , Braunlin Bill , Beadling Les 
Published: February 2009

AbstractWe report a highly selective technique for the rapid and label-free analysis of nucleic acid sample using Metal Oxide Semiconductor (MOS) capacitive sensors. The binding of charged macromolecules such as DNA on the surface of these Field Effect Devices modifies the charge distribution in the Semiconductor (Si) region of the sensor. These changes are manifested as a significant shift in the Capacitance-Voltage (C-V) characteristics measured across the device. The speed and selectivity of the detection process is enhanced by the use of external electric field of controlled intensity. This simple and high-throughput sensing technique holds promises for the future electronic DNA arrays and Lab-on-a chip devices
Nanorods as a precursor for high quality GaN layers
Authors: Cherns David , Griffiths Ian , Khongphetsak Somboon , Novikov Sergei , Farley Nicola , Campion Richard , Foxon Tom 
Published: February 2009

ABSTRACTThe density of threading dislocations in GaN/(0001)sapphire films grown by molecular beam epitaxy can be reduced to about 108 cm−2 by growing an intermediate nanorod layer. This paper examines the growth of the nanorods and proposes that threading defects in the overlayer arise either through grain boundaries formed when nanorods coalesce, or through the propagation of dislocation dipoles seen during nanorod growth. Results showing that the latter often terminate or develop into voids during growth are discussed.
Effects of an Applied Electric Field on Silicon Nanocrystals Photoluminescence
Authors: Lacombe Alexandre , Barba David , Beaudoin Félix , Martin François , Ross Guy G. 
Published: February 2009

AbstractThe photoluminescence (PL) of silicon nanocrystals (Si-nc) obtained by ion implantation in the oxide layer of a MOS structure was measured during the application of a slowly varying electric field generated by biasing the gate electrode. As a result, both PL intensity enhancement and quenching have been observed. These reproducible intensity modulations exhibit a hysteresis effect when the applied electric field is varied and persist even after it is removed. The behavior of the current density and the absence of wavelength shift in the PL spectra during gate voltage sweeps suggest that these modulations are related to the motion of charge carriers rather than to field-induced mechanisms such as quantum-confined Stark effect (QCSE).
Light Emission from Three-Dimensional Silicon-Germanium Nanostructures
Authors: Lockwood David J. , Baribeau J.-M. , Lee E.-K. , Chang H.-Y. , Tsybeskov Leonid 
Published: February 2009

AbstractThree-dimensional SiGe nanostructures grown on Si using molecular beam epitaxy exhibit photoluminescence (PL) in the important spectral range of 1.3–1.6 μm. At a higher level of photo-excitation, thermal quenching of the PL intensity is suppressed and the previously accepted type II energy band alignment at Si/SiGe cluster hetero-interfaces no longer controls radiative carrier recombination. Instead, a dynamic type I energy band alignment governs the strong decrease in carrier radiative lifetime and further increase in the luminescence quantum efficiency. In contrast to the strongly temperature dependent and slow radiative carrier recombination found in bulk Si, Auger mediated PL emanating from the nanometer-thick Si layers is found to be nearly temperature independent with a radiative lifetime approaching 10−8 s, which is comparable to that found in direct band gap III-V semiconductors. Such nanostructures are thus potentially useful as CMOS compatible light emitters and in optical interconnects.
Toxicity Effect of Cancer Cell Labeled with Visible Luminescent Nanocrystalline Silicon Particles and Visualization Observationin Vivo
Authors: Sato Keisuke , Hiruoka Masaki , Fujioka Kohki , Fukata Naoki , Hirakuri Kenji , Yamamoto Kenji 
Published: February 2009

AbstractCytotoxicity of human cervical carcinoma cell line (HeLa cells) labeled with the nanocrystalline silicon (nc-Si) particles before and after ultraviolet (UV) light exposure has studied on the viability and cellular membrane damages. The viability and cellular membrane damages of HeLa cells changed at high particle concentration of 1.12 mg/ml. The viability of HeLa cells labeled with the UV-exposed nc-Si particles was higher than that of unexposed nc-Si particles. However, the variation of cellular membrane damages was almost same for the nc-Si particles before and after UV exposure. These results substantiated the low toxicity of nc-Si particles. Moreover, the HeLa cells labeled with the nc-Si particles exhibited green fluorescence. On the other hand,in vivotest of nc-Si particles estimated by the visualization observation of the circulation from the lymphatic vessel to the lymph node of a mouse. The transfer pathway of nc-Si particles could be clearly monitored by the strong emission of red light.
Nanofabrication of High-resolution and Nanofocusing X-ray Optics Based on Silicon and Diamond: Obstacles and Progress
Authors: Isakovic Abdel F. , Evans-Lutterodt K. , Stein A. , Warren J. B. , Narayanan S. , Sandy A. R. 
Published: February 2009

AbstractNanofocusing, high-resolution X-ray optics demand good surface quality, the absence of tapered sidewalls, and a depth reaching into tens, sometimes hundreds of microns, all requirements that must be satisfied over large areas. In this report, we discuss our motivation for choosing group IV materials (predominantly Si, and C in its diamond form) for nanofocusing and high resolution in the hard X-ray portion of the spectrum. We elaborate on the design and nanofabrication procedures, and detail the etching parameters that offer a path for overcoming obstacles in making better optics. We briefly review tests for the assessing the quality of the optics.
ZnS, CdS and ZnxCd1-xS Thin Films from Zn(II) and Cd(II) Complexes of 1, 1, 5, 5-Tetramethyl-2-4-dithiobiuret As Single Molecular Precursors
Authors: Ramasamy Karthik , Malik Mohammad A. , O'Brien Paul , Raftery James 
Published: February 2009

AbstractSynthesis of zinc and cadmium complexes of 1, 1, 5, 5-tetramethyl-2-4-dithiobiuret (M{N(SCNMe2)2}2) (M = Zn, Cd) is described together with X-ray single crystal of cadmium complex. These complexes have been used as a single molecular precursor for the deposition of ZnS, CdS and ZnxCd1-xS thin films by aerosol assisted chemical vapour deposition (AACVD) method. Adherent specular films of ZnS and CdS were obtained in the temperature range 300 – 500 °C. Hexagonal ZnxCd1-xS films were obtained at 400 °C by varying the precursor concentration. XRD of ZnS films showed cubic to hexagonal phase conversion above 350 °C. SEM showed that the morphology of the films varied depending on the deposition temperature. Films were also characterized by atomic force microscopy (AFM). To the best of our knowledge these complexes are the first in its class to be used as a single molecular precursor to deposit ZnS, CdS, and ZnxCd1-xS thin films.