bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adhesion of Lipid Membranes Mediated by Electrostatic and Specific Interactions
Authors: Maier Christian W. , Behrisch Almuth , Kloboucek Annette , Merkel Rudolf 
Published: April 2011

AbstractWe used the micropipet aspiration technique for a study of biomembrane adhesion. Adhesion was caused by contact site A, a highly specific cell adhesion molecule, reconstituted in lipid vesicles of DOPC with 5 %(mol/mol) DOPE-PEG2000. We found adhesion and subsequent receptor aggregation in the contact zone. Additionally, electrostatic modulation of membrane adhesion was studied. Whereas addition of the negatively charged lipid SOPS to the lecithin (SOPC) host membrane suppressed adhesion due to electrostatic repulsion, a positively charged lipid (DOTAP) was surprisingly ineffective. This might be due to either phase separation of the mixture or DOTAP changing other membrane properties as bending stiffness and the Hamaker constant.
A Three-Dimensional Monte Carlo Model for Phosphorus Implants into (100) Single-Crystal Silicon
Authors: Son Myung-Sik , Hwang Ho-Jung 
Published: April 2011

ABSTRACTAn alternative three-dimensional (3D) Monte Carlo (MC) dynamic simulation model for phosphorus implant into (100) single-crystal silicon has been developed which incorporates the effects of channeling and damage. This model calculates the trajectories of both implanted ions and recoiled silicons and concurrently and explicitly affects both ions and recoils due to the presence of accumulative damage. In addition, the model for room-temperature implant accounts for the self-annealing effect using our defined recombination probabilities for vacancies and interstitials saved on the unit volumes. Our model has been verified by the comparison with the previously published SIMS data over commonly used energy range between 10 and 180 keV, using our proposed empirical electronic energy loss model. The 3D formations of the amorphous region and the ultra-shallow junction around the implanted region could be predicted by using our model, TRICSI (TRansport Ions into Crystal-Silicon).
Atomie Force Microscope Study of Two-Dimensional Dopant Delineation by Selective Chemical Etching
Authors: Choi Kwang-Ki , Seong Tae-Yeon , Lee Seonghoon , Hwang Hyunsang , Sohn Yong Sun 
Published: April 2011

ABSTRACTSelective chemical etching and atomic force microscope (AFM) examination has been performed to delineate two-dimensional (2-D) dopants profiles of p/n-type well and junction areas. Selectivity strongly depended on the types of dopants and the ratio of etching solutions. Calibration showed that the carrier concentrations in both p/n-type regions could be delineated down to a level of ∼1×1017/cm3. The AFM-induced profiles were compared with the calculated data provided by the 2-D process simulators such as TRIM and SUPREM-IV.
Characterization of Interatomic Potentials by a Calculation of Defect Energy
Authors: Kogure Y. , Doyama M. 
Published: April 2011

ABSTRACTPotential functions used in molecular dynamics simulations for metals are characterized through a calculation of the third-order elastic constants, the Gruneisen parameters, and the molecular dynamics simulation of point defects. The Lennard-Jones potential and the embedded atom method potentials for noble metals (Cu, Ag, Au) are characterized by using a common program code.
A Tight-Binding Model for Optical Properties of Porous Silicon
Authors: Cruz M. , Beltran M. R. , Wang C. , Tagüeña-Martinez J. 
Published: April 2011

ABSTRACTSemi-empirical tight-binding techniques have been extensively used during the last six decades to study local and extended defects as well as aperiodic systems. In this work we propose a tight-binding model capable of describing optical properties of disordered porous materials in a novel way. Besides discussing the details of this approach, we apply it to study porous silicon (p-Si). For this purpose, we use an sp3s* basis set and supercells, where empty columns are digged in the [001] direction in crystalline silicon (c-Si). The disorder of the pores is considered through a random perturbative potential, which relaxes the wave vector selection rule, resulting in a significant enlargement of the optically active k-zone. The dielectric function and the light absorption spectra are calculated. The results are compared with experimental data showing a good agreement.
Tight-Binding Formalism for Ionic Fullerides and its Application to Alkali-C60 Polymers
Authors: Saito Susumu , Louie Steven G. , Cohen Marvin L. 
Published: April 2011

ABSTRACTWe present a tight-binding formalism which can properly treat various ionic füllendes. In the Hamiltonian we include the intrafullerene Coulomb repulsion energy and the Madelung energy of the ionic lattice, both of which depend on the possible charge disproportion between fullerenes. This Hamiltonian requires a self-consistent treatment, but it is applicable to much larger systems than first-principles methods. Using this formalism we have studied the electronic structure of the one-dimensional A1C60 polymer. The present generalization of the tight-binding model is found to be important for ionic füllendes and a moderate-amplitude charge-density-wave state is found to be a possible stable state.
Effective Interatomic Interactions VIA The TB-LMTO Method
Authors: Drchal V. , Kudrnovský J. , Pasturel A. , Turek I. , Weinberger P. , Gonis A. , Turchi P. E. A. 
Published: April 2011

ABSTRACTThe energetics of metallic alloys, their surfaces or interfaces, and magnetic multilayers is studied in terms of effective interatomic (or interlayer) interactions that are determined from ab initio electronic structure calculations using the TB-LMTO method combined with the coherent potential approximation and the method of surface Green functions. First the theoretical background (force theorem, Lloyd formula, generalized perturbation method for bulk and surfaces, vertex cancellation theorem, method of infinitesimal rotations) is discussed, and then the applications to the phase stability of bulk alloys, surface segregation in disordered alloys, magnetism-induced ordering in two- and three-dimensional systems, phase diagram of two-dimensional alloys, interlayer exchange coupling in metallic multilayers, and the construction of Heisenberg-like Hamiltonians for magnetic systems are presented.
Magnetotransport in Thin Films of Lan-nxCa1+nxMnnO3n+1 (n=2,3, and ∞)
Authors: Asano H. , Hayakawa J. , Matsui M. 
Published: April 2011

ABSTRACTWith a use of the epitaxial a-axis thin films of perovskite series Lan-nxCa1+nxMnnO3n+1 (n=2,3, and ∞) with fixed carrier concentration (x=0.3), the transport properties of the series compounds have been examined to be associated with the difference in the number of the MnO2 layers. Results have indicated that a reduction in the number of layers results in systematic changes in the various features. These include an increase in resistivity, a decrease in resistivity peak temperature Tcρ corresponding to the metal-insulator transition, an enhancement of the maximum MR near Tcρ, and an increase in low temperature intrinsic MR. In order to explain the variation in these features with the number of MnO2 layers, it is necessary to take both anisotropie c-axis transfer interaction and two-dimensional spin fluctuation into account.
The Magentic Susceptibility in Ultrathin Films of Magnetic Materials
Authors: Ghatak Kamakhya P. , Bose P. K. , Majumder Gautam 
Published: April 2011

ABSTRACTIn this paper we have studied the dia and paramagentic susceptibilities of the holes in ultrathin films of magnetic materials in the presence of a parallel magentic field on the basis of a newly derived dispersion law for such systems. The numerical computations are performed taking Hg1-xMnx Te and Cd1-xMnx Se as examples. Both the susceptibilities increses with decreasing doping and film thickness respectively. It is important to note that not only the paramagnetic-to-diamagnetic susceptibility ratio for the present case deviates from (1/3) in conventional semiconductors, but also that is a critical region, where quenching of the diamagnetic occurs. The theoretical analysis is in agreement with the experimental datas as given elsewhere.
Sub-200 Oe Giant Magnetoresistance in Manganite Tunnel Junctions
Authors: Xiao Gang , Gupta A. , Li X. W. , Gong G. Q. , Sun J. Z. 
Published: April 2011

ABSTRACTMetallic manganite oxides, La1-xDxMnO3 (D=Sr, Ca, etc.), display “colossal” magnetoresistance (CMR) near their magnetic phase transition temperatures (Tc) when subject to a Tesla-scale magnetic field. This phenomenal effect is the result of the strong interplay inherent in this class of materials among electronic structure, magnetic ordering, and lattice dynamics. Though fundamentally interesting, the CMR effect achieved only at large fields poses severe technological challenges to potential applications in magnetoelectronic devices, where low field sensitivity is crucial. Among the objectives of our research effort involving manganite materials is to reduce the field scale of MR by designing and fabricating tunnel junctions and other structures rich in magnetic domain walls. The junction electrodes were made of doped manganite epitaxial films, and the insulating barrier of SrTiO3. The interfacial expitaxy has been imaged by using high-resolution transmission electron microscopy (TEM). We have used self-aligned lithographic process to pattern the junctions to micron scale in size. Large MR values close to 250% at low fields of a few tens of Oe have been observed. The mechanism of the spin-dependent transport is due to the spin-polarized tunneling between the half-metallic electrodes, in which the spins of the conduction electrons are nearly fully polarized. We will present results of field and temperature dependence of MR in these structures and discuss the electronic structure of the manganite inferred from tunneling measurement. Results of large MR at low fields due to the grain-boundary effect will also be presented.
In-Situ X-Ray Characterization of LiMn2O4: A Comparison of Structural and Electrochemical Behavior
Authors: Rodriguez Mark A. , Ingersoll David , Doughty Daniel H. 
Published: April 2011

ABSTRACTLixMn2O4 materials are of considerable interest in battery research and development. The crystal structure of this material can significantly affect the electrochemical performance. The ability to monitor the changes of the crystal structure during use, that is during electrochemical cycling, would prove useful to verify these types of structural changes. We report in-situ XRD measurements of LiMn2O4 cathodes with the use of an electrochemical cell designed for in-situ X-ray analysis. Cells prepared using this cell design allow investigation of the changes in the LiMn2O4 structure during charge and discharge. We describe the variation in lattice parameters along the voltage plateaus and consider the structural changes in terms of the electrochemical results on each cell. Kinetic effects of LiMn2O4 phase changes are also addressed. Applications of the in-situ cell to other compounds such as LiCoO2 cathodes and carbon anodes are presented as well.
Demonstration of Mixed Metal Oxide Cathode Materials in Prismatic Li-ion Cells
Authors: Ehrlich G. M. , Gitzendanner R. L. 
Published: April 2011

AbstractRecent advances in mixed metal oxide (LiNi1−xCoxO2) cathode materials for lithium ion (Li-ion) batteries have resulted in a new generation of high capacity cathode materials. High capacity materials are particularly useful for applications where either volume or weight is limited, such as in space applications. These applications also benefit from cell chemistries with high energy efficiency as this permits reduced ancillary energy storage and dissipation apparatus. Mixed metal oxide materials have been evaluated and demonstrated in prismatic Li-ion cells. The capacity of the mixed metal oxide materials is exceptional, reversible capacity of 160mAh/g is demonstrated although the cell voltage is lower than when LiCoO2 materials are used, 3.58V vs. 3.74V, at low (0.5mA/cm2) discharge rates. The high capacity results in a significant improvement in specific energy, further, the sloping discharge curve characteristic of the mixed metal oxide materials facilitates determination of the state of charge based on cell voltage. The design of composite cathode materials using the mixed metal oxide materials has a significant influence on the cell impedance and the rate capability of the material. Results describing the rate capability of these materials is presented.
Ionically Conducting Glasses with Subambient Glass Transition Temperatures
Authors: Dillon R. E. , Shriver D. F. 
Published: April 2011

ABSTRACTCryptands and crown ethers along with the lithium salt, LiCF3SO2N(CH2)3OCH3 (LiMPSA) were employed to produce a new type of amorphous electrolyte. The key to producing an amorphous phase was the mismatch between the cavity size of the macrocycle and the diameter of the cation. The addition of poly(bis-(2(2-methoxyethoxy)ethoxy)phosphazene) (MEEP) to the amorphous complex, LiMPSA/2.2.2 Cryptand, imparts improved electrochemical and viscoelastic properties. Conversely, when poly(sodium-4-styrenesulfonate) (PS4SS) is added to the amorphous complex, LiMPSA/2.2.2 Cryptand, the product crystallizes. The ionic conductivity of the MEEP rubbery electrolyte is a full order of magnitude higher when compared to the analogous PS4SS doped electrolyte (3.8×10−5 S cm−1 (MEEP), 1.7×10−6 S cm1 (PS4SS) both at 30°K).
Dry Composite Polymer Electrolytes for Lithium Batteries
Authors: Appetecchi G. B. , Croce F. , Dautzenberg G. , Scrosati B. 
Published: April 2011

AbstractThe synthesis, characteristics and properties of a PEO-based, dry composite electrolyte are presented and discussed. The major feature of this electrolyte is the high stability towards the lithium metal electrode. This unique property makes the electrolyte quite promising for the development of rechargeable polymer lithium batteries.
Thermoelectric Properties and Electronic Structure of BaBiTe3
Authors: Chung Duck-Young , Jobic Stéphane , Hogan Tim , Kannewurf Carl R. , Brec Raymond , Rouxel Jean , Kanatzidis Mercouri G. 
Published: April 2011

AbstractThe compound BaBiTe3 was prepared by the reaction of Ba/Bi/Te at over 700 °C either in K2TE4 or BaTe3 flux and was recrystallized in Ba/Te3 flux. The black rod-shaped polycrystalline material crystallizes in the orthorhombic space group P212121 with a=4.6077(2) A, b=17.0437(8) Å, c=18.2997(8) Å. Its structure is made of interdigitating columnar anionie [Bi4Te10(Te2)] ∞2+ “herring-bone” shaped segments which arrange into layers with Ba ions between them. The electrical conductivity, thermopower, thermal lattice conductivity, infrared absorption properties of this material suggest it is a narrow gap semiconductor.
Nucleation and Growth at Reactive Interfaces Followed by Impedance Measurements
Authors: Voiron F. , Ignat M. , Marieb T. , Fujimoto H. 
Published: April 2011

ABSTRACTTo evaluate the thickness of different constitutive layers of a TiAl multilayer, two different experiments, based on impedance measurements on multilayers, have been performed. In the first one, the thickness of the layer is deduced from resistivity measurements, applied to a parallel resistance model. In the second one, the thickness of the layer is deduced from comparing of calculated and measured values of surface potentials.
Magnetic Transitions Studied by Electrically Based Methods in Mn-Zn Ferrite
Authors: Gutiérrez P. , Peláiz A. , Huanosta A. , Valenzuela R. 
Published: April 2011

ABSTRACTThe thermal variations in electrical conductivity of polycrystalline Mn-Zn ferrites was investigated by impedance spectroscopy. Two well defined semicircles were observed in complex impedance plots, which were associated with grain (or bulk) and grain boundary impedance response, for the high and low frequency ranges, respectively. From these results, the characteristic relaxation frequencies were obtained for each process. The grain boundary frequency exhibited a monotonous behavior as a function of temperature, while the bulk frequency showed a maximum at 132 °C. By a magnetic method, it was verified that this temperature corresponds to the Curie transition. These results show therefore that a magnetic phase transition can be studied by means of electrical methds.
Reflection High-Energy Electron Diffraction as an Intrinsic Material Property Sensor for Machine Condition Transfer Function in Molecular Beam Epitaxial Growth of III-V Compound Semiconductors
Authors: Chen P. , Wangt C. , Madhukar A. , Khant T. , Small A. , Yan Z. , Viswanathan R. 
Published: April 2011

ABSTRACTA new approach is introduced for identifying a relation between the growth parameters measured in two molecular beam epitaxy systems, thereby realizing transfer of optimized growth conditions transfer. Test results show that the proposed approach is promising.
X-ray Diffraction Study of Laser-Material Interactions with an Ultrafast Table-Top X-ray Source
Authors: Guo T. , Rose-Petruck C. , Jimenez R. X. , Squier J. A. , Walker B. C. , Wilson K. R. , Barty C. P. J. 
Published: April 2011

ABSTRACTX-ray diffraction, employing a table-top, laser-driven x-ray source, has been used to investigate laser-material interactions with simultaneous picosecond and subatomic range distance resolution. The x-ray source, consisting of a table-top terawatt laser system and a moving Cu wire target apparatus, generates ˜ 5 × 1010 photons (4π steradians s)−1 of Cu Kα radiation. The lattice dynamics of the (111) planes of GaAs single crystals has been studied after the crystal is exposed to intense femtosecond laser pulses. The diffraction results have yielded information about the timescale of the lattice dynamics in the picosecond range and an upper limit for the width of the xray pulses. Initial strain, defined as the percentage of lattice distortion resulted from the laser illumination, is as high as 0.25% and is followed by an exponential decay with a time constant of ˜ 150 ps. Increases in the diffraction intensity after the laser irradiation have also been observed, likely due to a transition from dynamic to kinematic diffraction associated with degradation of the crystal.
Million-Line Failure Distributions for Narrow Interconnects
Authors: Bartelt M. C. , Hoyt J. J. , Bartelt N. C. , Dike J. J. , Wolfer W. G. 
Published: April 2011

ABSTRACTWe examine the distribution of failure times in a simple and computationally efficient, yet reasonably authentic, model of interconnect reliability that allows consideration of statistically significant samples. The model includes an approximate description of the distribution of grain sizes and texture in narrow interconnects, an effective treatment of stress evolution associated with mass transport along grain boundaries, and local relaxation of stresses due to void formation. Failure time distributions for populations of idealized structures are analyzed to aid in interpretation of model behavior.
Macro-and Microstrain Relaxation in Annealed Ag Films During Ageing at Room Temperature
Authors: Currie R. C. , Delhez R. , Mitiemeijer E. J. 
Published: April 2011

ABSTRACTThe relaxation of thermally induced strain in 500 nm thick polycrystalline Ag layers electron-beam deposited onto Si wafers was traced during ageing at room temperature. The layers consisted predominantly of matrix crystallites with {111} planes parallel to the surface and twin crystallites with {51 l} planes parallel to the surface. The macrostrain in the plane of the layer was determined from the X-ray diffraction line-profile position and the microstrain from the diffraction-line broadening. The residual macrostress relaxed from 160 MPa to 30 MPa in the matrix crystallites and from 170 MPa to 50 MPa in the twin crystallites. Simultaneously with the decrease in macrostress the microstrain decreases significantly for both texture fractions. The strain relaxation behaviour is governed by movement and subsequent annihilation of defects in the layer.
The Use of X-ray Topography to Map Mechanical, Thermomechanical and Wire-Bond Strain Fields in Packaged Integrated Circuits
Authors: McNally Patrick J. , Rantamäki R. , Curley John W. , Tuomi T. , Danilewsky A. N. , Herbert P. A. F. 
Published: April 2011

ABSTRACTThermal processing steps in the production of packaged integrated circuits can lead to thermomechanical stresses. Additionally, the process of bonding wires to contact pads can lead to strain fields attributable to these. Synchrotron x-ray topography has been applied to packaged EEPROM Si ICs in order to produce maps of the strain fields induced by such processing steps. This technique allows for depth-resolved mapping with resolutions currently in the region of 5–10 μm throughout the entire mapping volume.
Improved Tribological Behavior of Boron Implanted Ti-6A1-4V
Authors: Baker N. P. , Walter K. C. , Nastasi M. 
Published: April 2011

ABSTRACTPrevious research has compared the mechanical properties of Ti6A14V implanted with nitrogen using the plasma source ion immersion process and Ti6A14V implanted with boron using the beamline process [1]. Although the nitrogen implanted Ti6A14V had superior wear resistance it was concluded that the wear resistance of boron implanted Ti6AI4V might be improved to comparable levels if boron were implanted at lower energies to increase the concentration of boron at the surface. Boron implantation of Ti6A14V has been conducted at combinations of 32 and 40 keV to supplement that done previously at 75 keV. Shallower boron depth profiles with higher B-concentrations in the Ti64 surface have been obtained by tailoring the combinations of ion energy and dose. This work used three different ion energy and dose combinations of 4×1017 B-at/cm2 at 40 keV plus 2×1017 B-at/ cm2 at 32 keV, 4×1017 B-at/cm2 at 40 keV, and 4×1017 B-at/cm2 at 32 keV plus 2×1017 B-at/ cm2 at 40 keV. Comparisons are made between Ti6A14V with a shallow implanted boron depth profile, Ti6AI4V with a deeper boron depth profile and nitrogen implanted using a plasma source ion implantation process. It has been previously shown that while boron implanted Ti64 has a ~30% higher surface hardness than nitrogen implanted Ti64, the N-implantation reduced the wear coefficient of Ti64 by 25–120x, while B-implantation reduced the wear coefficient by 6.5x or less. The results show that no significant improvement is made in the wear resistance of boron implanted Ti6A14V by increasing the concentration of boron at the surface from approximately 10%to 43%. Transmission electron microscopy (TEM) and selected area diffraction (SAD) indicated the formation of crystalline TiB in the implanted surface layer. Shallower depth profiles result in reductions of the Ti6AI4V wear coefficient by 6.5x or less which is the same result obtained earlier with the deeper boron depth profile. Surface hardness of Ti6A14V with shallower boron depth profiles was improved approximately 10%compared to the results previously acquired with deeper boron depth profiles.