bluuebunny/crossref_metadata_2025 huggingface dataset:
Relating zircon and monazite domains to garnet growth zones: age and duration of granulite facies metamorphism in the Val Malenco lower crust
Authors: Hermann J. , Rubatto D.
Published: October 2010

Zircon from a lower crustal metapelitic granulite (Val Malenco, N‐Italy) display inherited cores, and three metamorphic overgrowths with ages of 281 ± 2, 269 ± 3 and 258 ± 4 Ma. Using mineral inclusions in zircon and garnet and their rare earth element characteristics it is possible to relate the ages to distinct stages of granulite facies metamorphism. The first zircon overgrowth formed during prograde fluid‐absent partial melting of muscovite and biotite apparently caused by the intrusion of a Permian gabbro complex. The second metamorphic zircon grew after formation of peak garnet, during cooling from 850 °C to c. 700 °C. It crystallized from partial melts that were depleted in heavy rare earth elements because of previous, extensive garnet crystallization. A second stage of partial melting is documented in new growth of garnet and produced the third metamorphic zircon. The ages obtained indicate that the granulite facies metamorphism lasted for about 20 Myr and was related to two phases of partial melting producing strongly restitic metapelites.

Monazite records three metamorphic stages at 279 ± 5, 270 ± 5 and 257 ± 4 Ma, indicating that formation ages can be obtained in monazite that underwent even granulite facies conditions. However, monazite displays less clear relationships between growth zones and mineral inclusions than zircon, hampering the correlation of age to metamorphism. To overcome this problem garnet–monazite trace element partitioning was determined for the first time, which can be used in future studies to relate monazite formation to garnet growth.
A simplified method for fabrication of a die holder
Authors: Rasetto Flavio H. , Driscoll Carl F. , Hawkes Lafeyette
Published: October 2010

A technique is described for fabricating a simple and inexpensive holder for dies to be used during the process of die spacer application.
Effect of denture cleansers, surface finish, and temperature on Molloplast B resilient liner color, hardness, and texture
Authors: Tan Han‐Kuang , Woo Andrew , Kim Silvia , Lamoureux Michael , Grace Michael
Published: October 2010

Purpose The purpose of this study was to compare color, texture, and Shore A hardness of a resilient silicone denture liner with as‐polymerized, roughened, or pumiced surfaces after treatment with perborate‐, persulfate‐, or hypochlorite‐containing denture cleansers at 25° or 55°.

Materials and Methods Fifty‐eight specimens that each exhibited an as‐polymerized, a roughened, and a pumiced area were exposed to 5 different commercially available perborate‐, persulfate‐, or hypochlorite‐containing denture cleansers at 25° or 55° continuously for 4 ½ months. The solutions were replaced twice a day. Control specimens were soaked in water with no cleanser. Before and after the 4 ½–month cleaning regimen, the color, hardness, and texture of resilient liner surfaces were evaluated using a color densitometer, a Shore A durometer (Shore Instrument & Mfg Co, Freeport, NY), and a surface profilometer, respectively. Differences among groups after the cleanser treatment were determined using a repeated measures analysis of variance (α= 0.05) and a Tukey's Honestly Significant Difference post hoc test.

Results Roughened specimen surfaces after 25° or 55° cleanser treatment exhibited significant color loss with some perborate‐containing cleansers compared with the control. Roughened specimens treated at 55° with perborate‐containing cleansers also exhibited significantly greater color loss than those treated with the persulfate‐containing cleanser. With roughened surfaces, significantly greater hardness was found with some perborate‐containing cleanser compared with a hypochlorite‐containing cleanser after treatment at 25°. No differences were observed in surface texture based upon cleanser treatment.

Conclusion After silicone resilient denture liner treatment with certain perborate‐containing denture cleansers, a greater amount of components could leach from the liner leading to a loss of color if the liner surface is rough.
Interchangeability of semiadjustable articulators after 2 to 7 years of use
Authors: Price Richard B.T. , Loney Robert W. , Andreou Pantelis
Published: October 2010

Purpose The purpose of this study was to test the interchangeability of articulators that had been in use from 2 to 7 years and compare these results with the interchangeability of the same articulators 1 year earlier.

Materials and Methods Forty‐six Whip Mix model #2240 articulators (Whip Mix Corporation, Louisville, KY) that were in clinical use from 2 to 7 years were checked for interchangeability using the Whip Mix #2245 check system. The horizontal tolerance of the check system was 94 μm. Articulators were also evaluated in the vertical dimension at 4 predetermined locations around the check system cylinders using 26‐μm—thick shimstock. Vertical discrepancies between the cylinders were recorded as the thickness of 0, 1, 2, or more than 2 pieces of shimstock. Interchangeability results were compared with those determined 1 year previously using the same evaluation methods using the Exact McNemar's Test of Agreement (α= 0.05).

Results Using the Whip Mix 2245 check system, 35 (76%) articulators were interchangeable after 2 to 7 years of use. This compares to 38 (83%) that were interchangeable upon evaluation 1 year earlier. The decrease in interchangeability was not significant (p= .4531). Forty‐three (94%) of the articulators had vertical discrepancies of 52 μm or less at the initial evaluation. One year later, 45 (98%) of the articulators had vertical discrepancies of 52 μm or less. After 1 year, there were significant differences in the amount of vertical space between the cylinders only at the right side (p= .014).

Conclusion The Whip Mix model #2240 articulator can remain interchangeable during clinical use for 7 years, but should be routinely checked for calibration.
The history and development of the dental surveyor: Part II
Authors: Engelmeier Robert L.
Published: October 2010

Part II of this series on the history and development of the dental surveyor reviews ways in which the basic dental surveyor has been modified to improve its accuracy and versatility.
Dimensional accuracy of dental casts: Influence of tray material, impression material, and time
Authors: Thongthammachat Sudsukh , Moore B. Keith , Barco M. Thomas , Hovijitra Suteera , Brown David T. , Andres Carl J.
Published: October 2010

Purpose This study evaluated the influence on dimensional accuracy of dental casts made with different types of trays and impression materials and poured at different and multiple times.

Materials and Methods Two types of stock trays (plastic stock tray, perforated metal stock tray) and 4 types of custom tray materials (autopolymerizing acrylic resin, thermoplastic resin, and 2 types of light‐polymerized acrylic resins) were used with 2 types of impression materials (addition polymerizing silicone and polyether), to make impressions of a metal master model. Each tray and impression material was used to make 5 impressions. Casts were made by multiple pourings at 30 minutes, 6 hours, 24 hours, and 30 days after impression making. Using a measuring microscope, 12 distances were calculated based on measurements of 8 reference points. The absolute value of the difference of each measurement was calculated, as was the corresponding measurement on the master model. A Bayesian model using a simple noninformative prior was used to analyze these data.

Results Statistical differences within 6 μm were found only with thermoplastic resin tray material for addition silicone, and for thermoplastic resin tray material and 1 type of light‐polymerized acrylic resin for polyether. Neither stock trays nor custom trays contributed to the differences in accuracy of the casts. All deviations in casts made with silicone impression material were within a clinically acceptable range. For the polyether, distortions occurred that were clinically unacceptable. Impressions made from polyether distorted over time. Silicone impression material has dimensional stability up to 30 days.

Conclusion Accurate casts can be made with either stock trays or custom trays. An impression made from polyether should be poured only once and within 24 hours after impression making, because of the distortion of the material over time. Silicone impression material has better dimensional stability than polyether.
Rehabilitation of a bulimic patient using endosteal implants
Authors: Ambard Alberto , Mueninghoff Leonard
Published: October 2010

This article describes the dental rehabilitation of a bulimic patient using endosteal implants. Although the patient, a 31‐year‐old woman with a long history of bulimia nervosa, had been receiving medical and psychological treatment, the condition was not completely controlled. Clinical examination revealed multiple crowns with extensive cervical caries. The prognosis for all remaining teeth was poor. After extractions, implant therapy was implemented to provide support for fixed prostheses. After the implants were uncovered and during provisional therapy, the peri‐implant tissue exhibited inflammation and lack of keratinized tissue requiring additional periodontal procedures before definitive restorations could be placed. Because of the difficulty in managing the peri‐implant tissue during the many phases of implant therapy, treatment was challenging. One year after treatment, the patient's low self‐esteem had improved substantially and her restorations provided satisfactory esthetics and function.
Modulated bone matrix‐related gene expression is associated with differences in interfacial strength of different implant surface roughness
Authors: Ogawa Takahiro , Sukotjo Cortino , Nishimura Ichiro
Published: October 2010

Purpose The objective of this study was to examine the effect of implant surface topography on biomechanical strength and expression patterns of bone extracellular matrix (ECM)‐related genes during implant healing.

Materials and Methods Cylinder implants with turned or dual acid‐etched (DE) surface were placed into the femurs of female Sprague‐Dawley rats. At 2 and 4 weeks after the implantation, the implant push‐in test was performed to measure the load‐bearing strength of the bone‐tissue interface. T‐shaped hollow implants were separately placed and the total RNA was extracted from the ingrown tissue within the hollow chamber. The RNA was subjected to reverse transcriptase polymerase chain reaction to analyze the expression pattern of selected bone extracellular matrix‐related genes.

Results The push‐in value of the DE implant is approximately 300% greater than that of the turned implant at weeks 2 and 4 (p=.0090). The expression of collagen II, osteocalcin and biglycan was higher in the week 2 DE implant group than the turned implant group. At week 4 the expression of collagen II and IX was 7‐ and 26‐fold, respectively, greater in the DE implant group than in the turned implant group.

Conclusions The surface topography of implants may induce the phenotypic alteration of wound healing cells. The increased interfacial strength of the DE implant may be associated with the modulated expression of the selected set of bone extracellular matrix genes.
Preclinical complete dentures curriculum survey
Authors: Rashedi Behnoush , Petropoulos Vicki C.
Published: October 2010

Purpose A survey of U.S. dental schools was conducted in 2001 to determine the curricular structure, teaching philosophies, and techniques used in preclinical complete denture courses.

Materials and Methods The questionnaire was mailed to the chairperson of the prosthodontic/restorative departments of 54 U.S. dental schools. Of these, 43 schools returned the completed survey, a response rate of 80%. The mean, median, and range of responses were computed where applicable.

Results Results from this survey show that the mean student‐to‐faculty ratio in the preclinical course was 12:1, with a median of 12:1 and a range of 6:1 to 27:1. The mean number of laboratory hours was 74, with a median of 70.5 and a range of 31.5 to 160. The mean number of lecture hours reported was 28, with a median of 25 and a range 12 to 80. The mean number of practical examinations was 3, with a median of 3 and a range of 0 to 11. Eighty‐four percent of the schools have prosthodontists teaching the course. The mean number of months that this course is taught is 5 months, with a median of 5 and a range of 2 to 13. Fifty‐eight percent of the schools use the Hanau semiadjustable articulator. Sixty‐five percent of the schools use protrusive records to set the articulator. The facebow preservation record is used by 84% of the schools.

Conclusions Preclinical complete denture educational programs vary from school to school, yet a large percentage of schools agree on certain topics. Only 28% of dental schools are incorporating new technologies, such as the internet, in their preclinical complete denture curriculum. Nineteen percent of dental schools are using only the Portrait denture teeth, which are newer than the Bioblend and Bioform teeth.
Removal of a metal‐ceramic fixed partial denture with a loose retainer
Authors: Verrett Ronald G. , Mansueto Michael A.
Published: October 2010

In clinical practice, it is necessary to remove a ceramic‐veneered fixed partial denture when an abutment becomes loose. When possible, the fixed partial denture is removed in a single piece, allowing recementation when appropriate. A 1‐piece removal is challenging, often putting the veneer and abutment teeth at risk for damage. This article describes a technique for fabricating and using a 2‐piece matrix that both protects the prosthesis and better directs removal forces along the long axis of the abutments.
Laboratory fabrication of gold occlusal surfaces for removable and implant‐supported prostheses
Authors: Lloyd Patrick M.
Published: October 2010

This article describes a technique for fabricating prosthetic teeth with gold occlusal surfaces for removable or implant‐supported prostheses. Following a successful wax try‐in appointment, the denture teeth used in the prosthesis are invested in a denture flask. After deflasking, the gingival 2/3 of the denture teeth are trimmed away. The remaining occlusal portions of the teeth are invested in a gypsum‐bonded investment and cast in a type III gold alloy. After polishing, the castings are repositioned back into their respective sites in the flask. An acrylic resin of an appropriate shade is mixed and packed in the flask. Once the acrylic resin is processed to the metal occlusal surfaces, the individual teeth are removed from the flask and polished. Then the finished teeth are reinserted in the wax trial denture, the occlusion is refined, the final wax‐up is completed, and the prosthesis is processed.
Food as a form of Destination Identity: A Tourism Destination Brand Perspective
Authors: Lin Yi-Chin , Pearson Thomas E. , Cai Liping A.
Published: October 2010

The study investigated the identity of food in relation to Taiwan as a tourism destination. Tourism brochures and destination websites were assessed. Thereafter, a comparison on the identity of food was drawn between the materials used in destination marketing and the perspectives of destination stakeholders. The findings illustrated that the structure of food identity in relation to a destination includes a core and extended identity. The core and extended identity of food in Taiwan is inconsistent to some extent, in terms of the type of food that best attracts international tourists. It is suggested that seven identified dimensions of food can be used to specify the aspects of food that can adequately reflect the characteristics of a destination; and, therefore, properly convey this to its intended markets. On the whole, food can be used as a form of destination brand identity and become a powerful means in building a destination brand.
Thomson-scattering measurements in the collective and noncollective regimes in laser produced plasmas (invited)
Authors: Ross J. S. , Glenzer S. H. , Palastro J. P. , Pollock B. B. , Price D. , Tynan G. R. , Froula D. H.
Published: October 2010

We present simultaneous Thomson-scattering measurements of light scattered from ion-acoustic and electron-plasma fluctuations in a N2 gas jet plasma. By varying the plasma density from 1.5×1018 to 4.0×1019 cm−3 and the temperature from 100 to 600 eV, we observe the transition from the collective regime to the noncollective regime in the high-frequency Thomson-scattering spectrum. These measurements allow an accurate local measurement of fundamental plasma parameters: electron temperature, density, and ion temperature. Furthermore, experiments performed in the high densities typically found in laser produced plasmas result in scattering from electrons moving near the phase velocity of the relativistic plasma waves. Therefore, it is shown that even at low temperatures relativistic corrections to the scattered power must be included.
Logarithmic correlators in nonrelativistic conformal field theory
Authors: Hosseiny Ali , Rouhani Shahin
Published: October 2010

We show how logarithmic terms may arise in the correlators of fields which belong to the representation of the Schrödinger–Virasoro algebra or the affine Galilean conformal algebra (GCA). We show that in GCA, only scaling operator can have a Jordan form and rapidity cannot. We observe that in both algebras, logarithmic dependence appears along the time direction alone.
Improvements of data quality of the LHD Thomson scattering diagnostics in high-temperature plasma experiments
Authors: Yamada I. , Narihara K. , Funaba H. , Hayashi H. , Kohmoto T. , Takahashi H. , Shimozuma T. , Kubo S. , Yoshimura Y. , Igami H. , Tamura N.
Published: October 2010

In Large Helical Device (LHD) experiments, an electron temperature (Te) more than 15 keV has been observed by the yttrium-aluminum-garnet (YAG) laser Thomson scattering diagnostic. Since the LHD Thomson scattering system has been optimized for the temperature region, 50 eV≤Te≤10 keV, the data quality becomes worse in the higher Te region exceeding 10 keV. In order to accurately determine Te in the LHD high-Te experiments, we tried to increase the laser pulse energy by simultaneously firing three lasers. The technique enables us to decrease the uncertainties in the measured Te. Another signal accumulation method was also tested. In addition, we estimated the influence of high-energy electrons on Te obtained by the LHD Thomson scattering system.
Negatively charged hydrogen at oxygen-vacancy sites in BaTiO3: Density-functional calculation
Authors: Iwazaki Yoshiki , Suzuki Toshimasa , Tsuneyuki Shinji
Published: October 2010

With a specific focus on defects formed from H atoms and oxygen vacancies (VO) in perovskite-type oxide, stability and stable valence states of complex defects formation processes within BaTiO3 are studied by using first-principle density-functional theory calculations. In our findings, H atoms diffuse as protons (H+) into interstitial sites in BaTiO3, whereas these atoms when trapped at centers of VO sites convert to negatively ionized states (H−). We also find that H atom trapping at VO sites occurs only in n-type carrier-rich environments without carrier compensation of VO2+ and H+. If carrier electrons are compensated, H+ ions are excluded from VO2+ sites due to the repulsive Coulomb potential existing between the H+ ion and the positively charged VO2+ site. Difficulties in the calculation of the diffusion-energy diagram for H atoms, involving essential changes in the stable valence states during the diffusion process, are discussed and a practical solution is presented.
Charging and dynamics of a dust grain in the wake of another grain in flowing plasmas
Authors: Miloch W. J. , Kroll M. , Block D.
Published: October 2010

The charging of a dust grain in supersonic plasma flows in the wake of another grain is studied by numerical simulations. While entering the Mach cone originating from the upstream grain, the grain is discharged by scattered ions. Electrostatic forces acting on the grain in the wake will move it to the stable position in the wake at a distance close to the electron Debye length from the upstream grain. The onset for discharging can be used to estimate the ion flow speed in the system. The simulations are carried out with the DiP3D code, a three-dimensional particle-in-cell code where both electrons and ions are represented as numerical particles [W. J. Miloch et al., Nonlinear Processes Geophys. 14, 575 (2007); New J. Phys. 11, 043005 (2009)].
Detection of lost alpha particle by concealed lost ion probe
Authors: Okamoto A. , Isobe M. , Kitajima S. , Sasao M.
Published: October 2010

Full orbit-following calculation is performed for the final orbit of the lost alpha particles, showing some orbits escaping from the last closed flux surface could be detected by a concealed lost ion probe (CLIP) installed under the shadow of the original first wall surface. While both passing and trapped orbits hit the same wall panel, detecting a trapped orbit by the CLIP is easier than detecting passing orbits. Whether the final orbit is detected or not is determined by the position of the reflection point. The CLIP successfully detects the trapped orbits, which are reflected before they hit to a first wall. Then the pitch angles of the orbits at the CLIP are close to and smaller than 90°. Optimization of the position of the CLIP in terms of broader detection window is investigated.
Optimization studies of the ITER low field side reflectometer
Authors: Diem S. J. , Wilgen J. B. , Bigelow T. S. , Hanson G. R. , Harvey R. W. , Smirnov A. P.
Published: October 2010

Microwave reflectometry will be used on ITER to measure the electron density profile, density fluctuations due to MHD/turbulence, edge localized mode (ELM) density transients, and as an L-H transition monitor. The ITER low field side reflectometer system will measure both core and edge quantities using multiple antenna arrays spanning frequency ranges of 15–155 GHz for the O-mode system and 55–220 GHz for the X-mode system. Optimization studies using the GENRAY ray-tracing code have been done for edge and core measurements. The reflectometer launchers will utilize the HE11 mode launched from circular corrugated waveguide. The launched beams are assumed to be Gaussian with a beam waist diameter of 0.643 times the waveguide diameter. Optimum launcher size and placement are investigated by computing the antenna coupling between launchers, assuming the launched and received beams have a Gaussian beam pattern.
Separation of junction and bundle resistance in single wall carbon nanotube percolation networks by impedance spectroscopy
Authors: Garrett Matthew P. , Ivanov Ilia N. , Gerhardt Rosario A. , Puretzky Alex A. , Geohegan David B.
Published: October 2010

Single wall carbon nanotube (SWNT) networks of different loadings were measured by impedance spectroscopy. The resistances of the junctions and bundles have been separated by modeling ac impedance spectroscopy data to an equivalent circuit of two parallel resistance-capacitance elements in series. The junction resistance was found to be 3–3.5 times higher than the bundle resistance. The dc and ac properties of the SWNT networks were found to obey a percolation scaling law, with parameters determined by dispersant type and SWNT purity. The values of the critical exponent in all cases were higher than the expected value of 1.3, which is related to widely distributed bundle and junction conductivities.
Visible-blind deep-ultraviolet Schottky photodetector with a photocurrent gain based on individual Zn2GeO4 nanowire
Authors: Li Chun , Bando Yoshio , Liao Meiyong , Koide Yasuo , Golberg Dmitri
Published: October 2010

We report on the visible-blind deep-ultraviolet (DUV) photodetectors with metal-semiconductor-metal (MSM) Schottky contacts based on individual Zn2GeO4 nanowire single-crystals. At an 8 V bias voltage, the device shows an extremely low dark current (<0.1 pA), a responsivity of 38.3 A/W (corresponding gain ∼200), a high DUV-to-visible discrimination ratio up to ∼104, and a relatively fast response time upon 245 nm DUV illumination. By analyzing the light-intensity-dependent photocurrent generation and carrier transport, the photogenerated holes trapped in Schottky barrier and shrinking of depletion region under DUV illumination at the metal/Zn2GeO4 interface are proposed for the carrier injection and the photocurrent gain.
Kinetic Alfvén wave instability in a Lorentzian dusty magnetoplasma
Authors: Rubab N. , Erkaev N. V. , Langmayr D. , Biernat H. K.
Published: October 2010

This study presents a theoretical approach to analyze the influence of kappa distributed streaming ions and magnetized electrons on the plasma wave propagation in the presence of dust by employing two-potential theory. In particular, analytical expressions under certain conditions are derived for various modes of propagation comprising of kinetic Alfvén wave streaming instability, two stream instability, and dust acoustic and whistler waves. A dispersion relation for kinetic Alfvén-like streaming instability has been derived. The effects of dust particles and Lorentzian index on the growth rates and the threshold streaming velocity for the excitation of the instability are examined. The streaming velocity is observed to be destabilizing for slow motion and stabilizing for fast streaming motions. It is also observed that the presence of magnetic field and superthermal particles hinders the growth rate of instability. Possible applications to various space and astrophysical situations are discussed.
Metamaterial high pass filter based on periodic wire arrays of multiwalled carbon nanotubes
Authors: Butt Haider , Dai Qing , Farah Petros , Butler Tim , Wilkinson Timothy D. , Baumberg Jeremy J. , Amaratunga Gehan A. J.
Published: October 2010

In this manuscript, we demonstrate metamaterials based on two-dimensional high density arrays of metallic multiwalled carbon nanotubes. They demonstrate a cutoff response toward electromagnetic waves and can be utilized for filtering applications. The plasma frequency, where the metamaterial displayed a sharp change in the reflection and transmission, depends on the geometry of their two-dimensional cubic lattice. A plasma frequency in the near infrared region of 1.5 μm was calculated numerically, for an array consisting of multiwalled nanotubes, having radius of 50 nm and lattice constant of 400 nm. Reflection experiments conducted on the nanoscale structures were in excellent agreement with numerical calculations.
Solution-processed ZnO nanocrystals in thin-film light-emitting diodes for printed electronics
Authors: Toyama Toshihiko , Takeuchi Hisazumi , Yamaguchi Daisaku , Kawasaki Hayato , Itatani Kazuki , Okamoto Hiroaki
Published: October 2010

Thin-film light-emitting diodes (LEDs) containing solution-processed ZnO nanocrystals (NCs) were prepared as printed electronics. The electroluminescent (EL) properties of thin-film LEDs were investigated along with the structural and photoluminescence (PL) properties of the ZnO NCs. Scanning electron microscope and x-ray diffraction studies revealed that the crystal sizes D were ranged from 5–11 nm, and can be controlled by varying growth time tG in the Zn2+/OH− solution at 40 °C. The time evolution of D was analyzed using Lifshitz–Slyozov–Wagner theory, showing that growth is limited by diffusion. The results of PL studies indicated that increases in the peak energies in the ultraviolet (UV) region could be attributed to the quantum-size effects on the exciton emission in the NCs with a small D, the ZnO surfaces became sufficiently passivated as D increases. Printed layers containing well-passivated ZnO NCs with different D of 8–11 nm were used as emission layers in thin-film LEDs together with pentacene hole transport layers. The current-voltage characteristics were analyzed using the trapped-charge-limited current mechanism. EL spectral measurements revealed the presence of weak UV emission that increased slightly as D decreased.
Curvature dependence of surface free energy of liquid drops and bubbles: A simulation study
Authors: Block Benjamin J. , Das Subir K. , Oettel Martin , Virnau Peter , Binder Kurt
Published: October 2010

We study the excess free energy due to phase coexistence of fluids by Monte Carlo simulations using successive umbrella sampling in finite L×L×L boxes with periodic boundary conditions. Both the vapor-liquid phase coexistence of a simple Lennard-Jones fluid and the coexistence between A-rich and B-rich phases of a symmetric binary (AB) Lennard-Jones mixture are studied, varying the density ρ in the simple fluid or the relative concentration xA of A in the binary mixture, respectively. The character of phase coexistence changes from a spherical droplet (or bubble) of the minority phase (near the coexistence curve) to a cylindrical droplet (or bubble) and finally (in the center of the miscibility gap) to a slablike configuration of two parallel flat interfaces. Extending the analysis of Schrader et al., [Phys. Rev. E 79, 061104 (2009)], we extract the surface free energy γ(R) of both spherical and cylindrical droplets and bubbles in the vapor-liquid case and present evidence that for R→∞ the leading order (Tolman) correction for droplets has sign opposite to the case of bubbles, consistent with the Tolman length being independent on the sign of curvature. For the symmetric binary mixture, the expected nonexistence of the Tolman length is confirmed. In all cases and for a range of radii R relevant for nucleation theory, γ(R) deviates strongly from γ(∞) which can be accounted for by a term of order γ(∞)/γ(R)−1∝R−2. Our results for the simple Lennard-Jones fluid are also compared to results from density functional theory, and we find qualitative agreement in the behavior of γ(R) as well as in the sign and magnitude of the Tolman length.
Polaron transport in TiO2 thin films
Authors: Yildiz Abdullah , Iacomi Felicia , Mardare Diana
Published: October 2010

Undoped and Fe-doped TiO2 thin films were obtained by rf-sputtering technique onto heated glass substrates (250 °C) covered with indium tin oxide. The temperature dependence of the electrical conductivity was investigated in the temperature range 13–320 K, and it shows that the conduction mechanism in the studied samples is described by small-polaron hopping (SPH) at temperatures higher than half of the Debye temperature (θD). It was found that the magnitude of the SPH coupling increases by Fe doping in TiO2 thin films. With decreasing temperature, the conduction behavior transited from SPH conduction to variable-range hopping (VRH) conduction. In the intermediate temperature domain (200 K<T<θD/2), the VRH conduction was found to be dominant, while a temperature-independent conductivity behavior was observed in the lower temperature range (T<200 K).
A critical test of bivelocity hydrodynamics for mixtures
Authors: Brenner Howard
Published: October 2010

The present paper provides direct noncircumstantial evidence in support of the existence of a diffuse flux of volume jv in mixtures. As such, it supersedes an earlier paper [H. Brenner, J. Chem. Phys. 132, 054106 (2010)], which offered only indirect circumstantial evidence in this regard. Given the relationship of the diffuse volume flux to the fluid’s volume velocity, this finding adds additional credibility to the theory of bivelocity hydrodynamics for both gaseous and liquid continua, wherein the term bivelocity refers to the independence of the fluid’s respective mass and volume velocities. Explicitly, the present work provides a new and unexpected linkage between a pair of diffuse fluxes entering into bivelocity mixture theory, fluxes that were previously regarded as constitutively independent, except possibly for their coupling arising as a consequence of Onsager reciprocity. In particular, for the case of a binary mixture undergoing an isobaric, isothermal, external force-free, molecular diffusion process we establish by purely macroscopic arguments—while subsequently confirming by purely molecular arguments—the validity of the ansatz jv=(v¯1−v¯2)j1 relating the diffuse volume flux jv to the diffuse mass fluxes j1(=−j2) of the two species and, jointly, their partial specific volumes v¯1,v¯2. Confirmation of that relation is based upon the use of linear irreversible thermodynamic principles to embed this ansatz in a broader context, and to subsequently establish the accord thereof with Shchavaliev’s solution of the multicomponent Boltzmann equation for dilute gases [M. Sh. Shchavaliev, Fluid Dyn. 9, 96 (1974)]. Moreover, because the terms v¯1, v¯2, and j1 appearing on the right-hand side of the ansatz are all conventional continuum fluid-mechanical terms (with j1 given, for example, by Fick’s law for thermodynamically ideal solutions), parity requires that jv appearing on the left-hand side of that relation also be a continuum term. Previously, diffuse volume fluxes, whether in mixtures or single-component fluids, were widely believed to be noncontinuum in nature, and hence of interest only to those primarily concerned with transport phenomena in rarefied gases. This demonstration of the continuum nature of bivelocity hydrodynamics suggests that the latter subject should be of general interest to all fluid mechanicians, even those with no special interest in mixtures.
Can we enhance two-dimensional electron gas from ferroelectric/GaN heterostructures?
Authors: Zhang Jihua , Yang Chuanren , Liu Ying , Zhang Min , Chen Hongwei , Zhang Wanli , Li Yanrong
Published: October 2010

Ferroelectric (FE)/semiconductor heterostructures are very promising for future electronic devices. This paper examined several kinds of devices based on heterostructures made from FE and GaN semiconductor. Results showed that although two-dimensional electron gas (2DEG) density in GaN could be tuned by the polarization of FE, it was harsh to enhance the 2DEG greatly for a practical structure even in theory. We proposed that beside the device process, structure design of the device was also important to 2DEG characteristics. To keep or enhance the 2DEG density need novel materials and/or device structures. Our theory predictions may provide some references to design of new electronic devices and promote experimental studies for FE/GaN heterostructures.
High density Langmuir probe array for NSTX scrape-off layer measurements under lithiated divertor conditions
Authors: Kallman J. , Jaworski M. A. , Kaita R. , Kugel H. , Gray T. K.
Published: October 2010

A high density Langmuir probe array has been developed for measurements of scrape-off layer parameters in NSTX. Relevant scale lengths for heat and particle fluxes are 1–5 cm. Transient edge plasma events can occur on a time scale of several milliseconds, and the duration of a typical plasma discharge is ∼1 s. The array consists of 99 individual electrodes arranged in three parallel radial rows to allow both swept and triple-probe operation and is mounted in a carbon tile located in the lower outer divertor of NSTX between two segments of the newly installed liquid lithium divertor. Initial swept probe results tracking the outer strike point through probe flux measurements are presented.
Precise multipole method for calculating many-body hydrodynamic interactions in a microchannel
Authors: Kędzierski Marcin , Wajnryb Eligiusz
Published: October 2010

We introduce a novel and precise method for computing many-body hydrodynamic interactions in a cylindrical microchannel. The method is generic in the sense that we can easily change the radius and the character of particles (hard spheres, droplets, permeable spheres, etc.). These features are not available in any of the existing methods. Comparison with the available results validates our method. In particular we obtain excellent agreement with the analytically known expression for the single particle friction coefficient. Additionally we observe negative hydrodynamic coupling for finite particles which are consistent with the recently reported effect for point particles. As an example we compute the velocities of polymeric chains of particles in parabolic flow and compare them to unbounded space. The method will be helpful in the understanding of physical and physicochemical processes in a wide range of bio-, geophysical, and microfluidic systems.
Resonant subband Landau level coupling in symmetric quantum well
Authors: Tung L.-C. , Wu X.-G. , Pfeiffer L. N. , West K. W. , Wang Y.-J.
Published: October 2010

Subband structure and depolarization shifts in an ultrahigh mobility GaAs/Al0.24Ga0.76As quantum well are studied using magnetoinfrared spectroscopy via resonant subband Landau level coupling. Resonant couplings between the first and up to the fourth subbands are identified by well-separated antilevel-crossing split resonance, while the hy-lying subbands were identified by the cyclotron resonance linewidth broadening in the literature. In addition, a forbidden intersubband transition (first to third) has been observed. With the precise determination of the subband structure, we find that the depolarization shift can be well described by the semiclassical slab plasma model and the possible origins for the forbidden transition are discussed.
Simulation of spin field effect transistors: Effects of tunneling and spin relaxation on performance
Authors: Gao Yunfei , Low Tony , Lundstrom Mark S. , Nikonov Dmitri E.
Published: October 2010

A numerical simulation of spin-dependent quantum transport for a spin field effect transistor is implemented in a widely used simulator, nanoMOS. This method includes the effect of both spin scattering in the channel and the tunneling barrier between the source/drain and the channel. Accounting for these factors permits setting more realistic performance limits for the transistor, especially the magnetoresistance, which is found to be lower compared to earlier predictions. The interplay between tunneling and spin scattering is elucidated by numerical simulation. Insertion of the tunneling barrier leads to an increased magnetoresistance. Simulations are used to explore the tunneling barrier design issues.
Effect of TiO2 nanoparticles on the thermal properties of decorated multiwall carbon nanotubes: A Raman investigation
Authors: de Zevallos-Márquez Angela M. O. , Brasil Maria José S. P. , Iikawa Fernando , Abbaspourrad Alireza , Verissimo Carla , Moshkalev Stanislav A. , Alves Oswaldo L.
Published: October 2010

We have investigated multiwalled carbon nanotubes decorated with TiO2 nanoparticles. Scanning electron microscopy and transmission electron microscopy measurements revealed that the TiO2 incorporates on the nanotubes forming large cauliflowerlike aggregates and/or small crystalline particles attached to the nanotube wall, depending on the growth conditions. A detailed Raman study was performed in pristine and a series of decorated nanotubes, where we analyzed both the Raman signal from the nanotubes and from the TiO2 nanoparticles. We demonstrate that the attached TiO2 nanoparticles affect significantly the thermal properties of the resulting hybrid nanostructure, as revealed by differentiated reactions to laser heating. This is a crucial point for modeling and optimization of devices based on nanotubes, which properties are strongly temperature dependent.
Broad energy-bands of continuous-network-structure molybdenum films
Authors: Anno Eiji
Published: October 2010

Interband absorption of continuous-network-structure (CNS) molybdenum films with a weight thickness below about 3 nm weakened and shifted to higher energies compared to interband absorption of continuous-thin molybdenum films with bulk energy bands. This weakening and shift agrees qualitatively with that observed in interband absorption of metal particles, which have energy bands broadened by lattice contraction. Based on this agreement, the weakening and shift in the CNS molybdenum films can be qualitatively ascribed to energy-band broadening. Thus, CNS molybdenum films with a weight thickness below about 3 nm have broader energy bands compared to bulk molybdenum.
Structural coherency of epitaxial graphene on 3C–SiC(111) epilayers on Si(111)
Authors: Ouerghi A. , Belkhou R. , Marangolo M. , Silly M. G. , El Moussaoui S. , Eddrief M. , Largeau L. , Portail M. , Sirotti F.
Published: October 2010

Graphene has emerged as a promising nanoelectronic material in electronic devices applications and studying two-dimensional electron gases with relativistic dispersion near Dirac point. Nonetheless, the control of the preparation conditions for homogeneous large-area graphene layers is difficult. Here, we illustrate evidence for high structural and electronic quality epitaxial graphene on 3C–SiC(111). Morphology and electronic structure of the graphene layers have been analyzed with low energy electron microscopy and angle resolved photoemission spectroscopy. Using scanning tunneling microscopy and scanning transmission electron microscopy, we show that graphene exhibits remarkably continuity of step edges suggesting the possibility of growing large scale graphene layer.
Interfacial spin polarization and resistance in lateral spin-valves incorporating Bi and BiPb thin films
Authors: Noh Jin-Seo , Lee Kyoung-Il , Lee Wooyoung
Published: October 2010

Electrical spin injection and detection have been investigated at cryogenic temperatures using a lateral spin-valve structure. Either Bi or BiPb was used as a nonmagnetic spin medium, while CoFe and NiFe were employed as the spin injector and spin detector, respectively. A large magnetoresistance signal corresponding to ΔR=1.2 mΩ was detected from the BiPb-based spin-valves. From this result, a large spin diffusion length of 230 μm and a high interfacial spin polarization of 10% were derived. From an independent calculation, it was found that the interfacial spin polarization and the associated spin accumulation are strongly correlated with the interfacial resistance.
Path-related unexpected injection charges in BaTiO3 ferroelectric thin films studied by Kelvin force microscopy
Authors: Guo Huifen , Cheng Gang , Wang Shujie , Dai Shuxi , Wu Sixin , Zhou Shaomin , Li Yuncai , Du Zuliang
Published: October 2010

The collective effect of injection charges constructed in a dot array using scanning probe microscopy (SPM) in BaTiO3 ferroelectric thin films was investigated with Kelvin force microscopy (KFM). Unexpected charges were observed in the SPM tip paths where poling bias was zero. The analysis of the array with different poling biases shows that the collective effect of the injection charges in the dot array induced a potential difference between film and tip, which in turn injected unexpected charges. The calculated potential difference distribution along the tip’s paths correlates well with KFM images of the unexpected charges.
Suppression of substrate oxidation during ozone based atomic layer deposition of Al2O3: Effect of ozone flow rate
Authors: Kwon Jinhee , Dai Min , Halls Mathew D. , Chabal Yves. J.
Published: October 2010

We demonstrate that interfacial SiO2, usually formed during high-κ oxide growth on silicon using ozone (O3), is suppressed during Al2O3 atomic layer deposition (ALD) by decreasing the O3 flow rate. First-principles calculations indicate that oxygen introduced by the first low-dose O3 exposure is inserted into the surface nucleation layer rather than the Si lattice. Subsequent Al2O3 deposition further passivates the surface against substrate oxidation. Aluminum methoxy [–Al(OCH3)2] and surface Al–O–Al linkages formed after O3 pulses are suggested as the reaction sites for trimethylaluminum during ALD of Al2O3.
Observation of dodecagon-shape V-defects in GaN/AlInN multiple quantum wells
Authors: Zhou Lin , McCartney Martha R. , Smith David J. , Mouti Anas , Feltin E. , Carlin J. F. , Grandjean N.
Published: October 2010

The microstructure of GaN(Si)/AlInN multiple quantum wells grown on GaN/Al2O3 (0001) templates by metalorganic vapor-phase epitaxy has been investigated using transmission electron microscopy and associated techniques. Dodecagon-shape V-defects with hexagonal apexes, which nucleate on screw-component threading dislocations, are observed at the film surface. The hexagonal apexes are bounded by {112̱1} planes, whereas the dodecagons are bounded by {101̱1} and {112̱1} planes, where the {101̱1} facets are generated from the edges between adjacent {112̱1} planes. Indium segregation is observed along these edges. A possible reason for formation of these defects is briefly discussed.
Importance of molecular alignment for organic photovoltaic devices
Authors: Xu Zong-Xiang , Roy V. A. L. , Liu Zeng-Tao , Lee C. S.
Published: October 2010

We study the effect of molecular alignment on the performance of organic photovoltaic devices (OPV) by using two porphyrin molecules of etioporphyrin-I (HOX) and octaethylporphyrin (HOEP) with similar chemical structures. Due to the minor differences in their peripheral substituents, the two porphyrin molecules form crystalline films of different molecular alignment. This has been verified by broader and redshift in the UV-vis absorption spectra as well as the grazing incidence x-ray diffraction of the films. OPV devices fabricated with these films show different performance. Stronger π-π stacking of HOX molecules exhibited better charge transport and photovoltaic performance than that of HOEP molecules.
Magnetic force microscopy of epitaxial magnetite films through the Verwey transition
Authors: Lee A. K. H. , Jayathilaka P. B. , Bauer C. A. , Monti M. C. , Markert J. T. , de Lozanne A. , Miller Casey W.
Published: October 2010

Magnetic force microscopy was performed on 300 nm thick magnetite films grown epitaxially on MgO (001) at temperatures ranging from well below to well above the Verwey transition temperature, TV. Frequency shift images were acquired at different locations on the sample as temperature was increased through the Verwey transition. The magnetic domain features are persistent at all temperatures, which indicates that the domains are pinned across the phase transition, probably due to antiphase boundaries. An enhancement of magnetic contrast below TV indicates the moments tilt out of the plane below TV, which is corroborated by superconducting quantum interference device magnetometry.
Diamagnetic shift of the A free exciton in CuGaSe2 single crystals
Authors: Luckert F. , Yakushev M. V. , Faugeras C. , Karotki A. V. , Mudryi A. V. , Martin R. W.
Published: October 2010

Single crystals of CuGaSe2 were studied using magnetophotoluminescence in magnetic fields up to 20 T at 4.2 K. The rate of the diamagnetic shift in the A free exciton peak was determined to be 9.82×10−6 eV/T2. This rate was used to calculate the reduced mass as 0.115m0, the binding energy as 12.9 meV, the Bohr radius as 5.1 nm and an effective hole mass of 0.64m0 (m0 is the free electron mass) of the free A exciton using a low-field perturbation approach and the hydrogenic model.
Tuning plasmonic interaction between gold nanorings and a gold film for surface enhanced Raman scattering
Authors: Ye Jian , Shioi Masahiko , Lodewijks Kristof , Lagae Liesbet , Kawamura Tatsuro , Van Dorpe Pol
Published: October 2010

We investigate the plasmonic properties of gold nanorings in close proximity to a gold film. The rings have been fabricated using nanosphere lithography and are optimized to boost their near-infrared surface enhanced Raman scattering (SERS) effects. A SERS enhancement factor as large as 1.4×107 has been achieved by tuning the separation between the gold nanorings and the gold film. In addition, we have numerically and experimentally demonstrated an enhanced tunability of the plasmon resonance wavelength and a narrowing of the plasmon linewidth for increasing ring-film interaction.