bluuebunny/crossref_metadata_2025 huggingface dataset:
The Japanese juxtaposition
Authors: PERNIOLA MARIO
Published: January 2006

Taking its starting point from the distinction between axial and non-axial civilization, the article focuses on the peculiar aspects of the Japanese process of modernization, which has its roots in a historical experience in which the notions of hybridity and crossing were unsuitable. In fact, what we see in Japan is not the encounter and mixture of different and heterogeneous aspects, although there is hardly anything original or pure in it. There is a sort of Japanese uniqueness, that cannot be found in a specific content, but in a general attitude that consists of a sort of deconstruction of any type of content. This process enables one thing to be put next to another without leading to conflict, even if originally the two may have been antithetical. Therefore, juxtaposition is the notion that best explains the type of procedure employed by the Japanese when they deal with something that does not come from their culture.
Cross-continental cross-fertilization in clothing
Authors: ROSS ROBERT
Published: January 2006

In this article, an attempt is made to explain the homogenization of world dress, particularly for men, and at the same time to understand why – in a number of places – that homogenization has been resisted, and specific forms of supposedly local clothing have been used as markers of identity. The argument revolves around two main themes. First, the development of continent, and later worldwide, systems of manufacturing and distribution of clothing, beginning in New York in the middle of the 19th century, allowed the spread of particular forms of dress. Secondly, this dress was seen as being modern. In some cases this led to its enthusiastic, or to its enforced, adoption, in the hope that it would bring about socio-economic modernization. Elsewhere, it was rejected as being a part of imperial domination.
Review of: Gene expression profiling identifies molecular subtypes of inflammatory breast cancer
Authors: Lønning P. E.
Published: January 2006

Citation of original article:

F. Bertucci, P. Finetti, J. Rougemont, E. Charafe-Jauffret, N. Cervera, C. Tarpin,et al. Gene expression profiling identifies molecular subtypes of inflammatory breast cancer.Cancer Research2005;65(6): 2170–8.

Abstract of the original article

Breast cancer is a heterogeneous disease. Comprehensive gene expression profiles obtained using DNA microarrays have revealed previously indistinguishable subtypes of non-inflammatory breast cancer (NIBC) related to different features of mammary epithelial biology and significantly associated with survival. Inflammatory breast cancer (IBC) is a rare, particular, and aggressive form of disease. Here we have investigated whether the five molecular subtypes described for NIBC (luminal A and B, basal, ERBB2 overexpressing, and normal breast-like) were also present in IBC. We monitored the RNA expression of approximately 8,000 genes in 83 breast tissue samples including 37 IBC, 44 NIBC, and 2 normal breast samples. Hierarchical clustering identified the five subtypes of breast cancer in both NIBC and IBC samples. These subtypes were highly similar to those defined in previous studies and associated with similar histoclinical features. The robustness of this classification was confirmed by the use of both alternative gene set and analysis method, and the results were corroborated at the protein level. Furthermore, we show that the differences in gene expression between NIBC and IBC and between IBC with and without pathologic complete response that we have recently reported persist in each subtype. Our results show that the expression signatures defining molecular subtypes of NIBC are also present in IBC. Obtained using different patient series and different microarray platforms, they reinforce confidence in the expression-based molecular taxonomy but also give evidence for its universality in breast cancer, independently of a specific clinical form.
Unidirectional polymerization leading to homochirality in the RNA world
Authors: Nilsson M. , Brandenburg A. , Andersen A. C. , Höfner S.
Published: January 2006

The differences between unidirectional and bidirectional polymerization are considered. The unidirectional case is discussed in the framework of the RNA world. Similar to earlier models of this type, where polymerization was assumed to proceed in a bidirectional fashion (presumed to be relevant to peptide nucleic acids), left- and right-handed monomers are produced via an autocatalysis from an achiral substrate. The details of the bifurcation from a racemic solution to a homochiral state of either handedness is shown to be remarkably independent of whether the polymerization is unidirectional or bidirectional. Slightly larger differences are seen when dissociation is allowed and the dissociation fragments are recycled into the achiral substrate.
Making media work in space: an interdisciplinary perspective on media and communication requirements for current and future space communities
Authors: Babidge S. , Cokley J. , Gordon F. , Louw E.
Published: January 2006

As humans expand into space communities will form. These have already begun to form in small ways, such as long-duration missions on the International Space Station and the space shuttle, and small-scale tourist excursions into space. Social, behavioural and communications data emerging from such existing communities in space suggest that the physically-bounded, work-oriented and traditionally male-dominated nature of these extremely remote groups present specific problems for the resident astronauts, groups of them viewed as ‘communities’, and their associated groups who remain on Earth, including mission controllers, management and astronauts’ families. Notionally feminine group attributes such as adaptive competence, social adaptation skills and social sensitivity will be crucial to the viability of space communities and in the absence of gender equity, ‘staying in touch’ by means of ‘news from home’ becomes more important than ever. A template of news and media forms and technologies is suggested to service those needs and enhance the social viability of future terraforming activities.
Tectonometamorphic evolution of the Aracena metamorphic belt (SW Spain) resulting from ridge‐trench interaction during Variscan plate convergence
Authors: Díaz Azpiroz M. , Fernández C. , Castro A. , El‐Biad M.
Published: January 2006

The Aracena metamorphic belt is a high‐temperature/low‐pressure (HT/LP) band located at the southern end of the European Variscan chain. It marks a suture between Armorica and Avalonia. This belt is characterized by (1) the presence of mid‐ocean ridge basalt‐derived metabasites that were affected by an inverted HT/LP metamorphism related to SW verging thrusting, whose thermal peak diachronously migrated eastward; (2) the occurrence of a HT/LP metamorphism, related to an extensional event, affecting continental rocks belonging to the Ossa Morena zone with peak temperatures that are ∼150°C higher than that recorded in the oceanic metabasites; and (3) the presence of near‐trench magmatism with high‐Mg andesite composition. These and other characteristics can be interpreted in terms of a ridge‐trench‐trench triple junction that migrated along the Armorican margin during Variscan oblique convergence.
A 20th century acceleration in global sea‐level rise
Authors: Church John A. , White Neil J.
Published: January 2006

Multi‐century sea‐level records and climate models indicate an acceleration of sea‐level rise, but no 20th century acceleration has previously been detected. A reconstruction of global sea level using tide‐gauge data from 1950 to 2000 indicates a larger rate of rise after 1993 and other periods of rapid sea‐level rise but no significant acceleration over this period. Here, we extend the reconstruction of global mean sea level back to 1870 and find a sea‐level rise from January 1870 to December 2004 of 195 mm, a 20th century rate of sea‐level rise of 1.7 ± 0.3 mm yr−1 and a significant acceleration of sea‐level rise of 0.013 ± 0.006 mm yr−2. This acceleration is an important confirmation of climate change simulations which show an acceleration not previously observed. If this acceleration remained constant then the 1990 to 2100 rise would range from 280 to 340 mm, consistent with projections in the IPCC TAR.
Suprathermal electron 90° pitch angle depletions at reverse shocks in the solar wind
Authors: Skoug R. M. , Gosling J. T. , McComas D. J. , Smith C. W. , Hu Q.
Published: January 2006

ACE/SWEPAM suprathermal electron pitch angle distributions often show depletions centered on and symmetric about 90 degree pitch angle. It has been suggested that these distributions can arise from a combination of focusing and mirroring of electrons associated with connection to magnetic field enhancements beyond the spacecraft. Assuming adiabatic particle motions, the width of the depletion in pitch angle is predicted to be a function of the strength of the magnetic field enhancement relative to the field at the measurement location. In this work, we test this model of depletion formation by examining depletions upstream from reverse shocks observed by ACE. Roughly symmetric depletions centered on 90 degree pitch angle were observed upstream from each of the 20 reverse shocks encountered by ACE from February 1998 to February 2003. In addition, the widths of the shock‐associated depletions are consistent with formation by adiabatic focusing and mirroring of electrons, providing strong support for the validity of this model.
In situ and experimental evidence for acidic weathering of rocks and soils on Mars
Authors: Hurowitz J. A. , McLennan S. M. , Tosca N. J. , Arvidson R. E. , Michalski J. R. , Ming D. W. , Schröder C. , Squyres S. W.
Published: January 2006

Experimental data for alteration of synthetic Martian basalts at pH = 0–1 indicate that chemical fractionations at low pH are vastly different from those observed during terrestrial weathering. Rock surface analyses from Gusev crater are well described by the relationships apparent from low‐pH experimental alteration data. A model for rock surface alteration is developed, which indicates that a leached alteration zone is present on rock surfaces at Gusev. This zone is not chemically fractionated to a large degree from the underlying rock interior, indicating that the rock surface alteration process has occurred at low water to rock ratio. The geochemistry of natural rock surfaces analyzed by APXS is consistent with a mixture between adhering soil/dust and the leached alteration zone. The chemistry of rock surfaces analyzed after brushing with the RAT is largely representative of the leached alteration zone. The chemistry of rock surfaces analyzed after grinding with the RAT is largely representative of the interior of the rock, relatively unaffected by the alteration process occurring at the rock surface. Elemental measurements from the Spirit, Opportunity, Pathfinder, and Viking 1 landing sites indicate that soil chemistry from widely separated locations is consistent with the low‐pH, low water to rock ratio alteration relationships developed for Gusev rocks. Soils are affected principally by mobility of Fe and Mg, consistent with alteration of olivine‐bearing basalt and subsequent precipitation of Fe‐ and Mg‐bearing secondary minerals as the primary control on soil geochemistry.
Response of reef island shorelines to seasonal climate oscillations: South Maalhosmadulu atoll, Maldives
Authors: Kench Paul S. , Brander Robert W.
Published: January 2006

The Maldives experience seasonal shifts in monsoon winds from the west‐northwest to northeast. The morphologic response of reef island beaches and shorelines to these predictable shifts in climate was examined on eight islands in South Maalhosmadulu Atoll based on global positioning system surveys of island shoreline planform in January and June 2002 and February 2003. Surveys show that islands exhibit large gross changes (31–120% of beach area) in shoreline position between seasons. Such changes reflect large reversals in sediment flux of 9–23 × 103 m3 on a biannual basis driven by seasonal reversals in wind and wave conditions. Annual net change is small (2–15%), suggesting islands spatially exhibit a dynamic equilibrium. An island oscillation index (Io) is defined that describes the spatial extent of shoreline change around islands. Island shape (ellipticity, e) is found to be positively correlated with Io in the expression Io = 1.021e − 0.275, suggesting island shape is a better indicator of the susceptibility of island shorelines to morphological change than wave energy exposure.
Remodelling epithelial tubes through cell rearrangements: from cells to molecules
Authors: Neumann Marc , Affolter Markus
Published: January 2006

Epithelial cell movements, such as those that occur during cell intercalation, largely contribute to the formation of epithelial structures during the morphogenesis of multicellular organisms. As the architecture of epithelial tissues relies on strong adhesion between cells at adherens junctions (AJs), the intercalation or rearrangements of epithelial cells might be controlled by modulating the adhesion dynamics of the AJs by internal or external forces. In this review, we describe recent progress in understanding cell rearrangements during epithelial tube remodelling and discuss several models that might account for the developmental control of the spatial dynamics of AJs.
The hypoxia‐inducible‐factor hydroxylases bring fresh air into hypoxia signalling
Authors: Berra Edurne , Ginouvès Amandine , Pouysségur Jacques
Published: January 2006

Metazoans rapidly respond to changes in oxygen availability by regulating gene expression. The transcription factor hypoxia‐inducible‐factor (HIF), which controls the expression of several genes, ‘senses’ the oxygen concentration indirectly through the hydroxylation of two proline residues that earmarks the HIF‐α subunits for proteasomal degradation. We review the expression, regulation and function of the HIF prolyl hydroxylases or prolyl hydroxylases domain proteins, which are genuine oxygen sensors.
Entropy production during reversible polymerization in nonideal systems
Authors: Stier Ulli
Published: January 2006

A general route is shown to calculate the entropy production σ as function of time t in a closed system during reversible polymerization. We treat the polymer molecules to behave nonideal and apply exemplarily the classical Flory-Huggins theory to get explicit expressions for the activity coefficient. At the beginning of the polymerization the system is in a nonequilibrium state where chemical reactions take place that irreversibly drive the system towards equilibrium with σ approaching zero in the limit t→∞. The time-dependent course of the entropy production is explicitly calculated for two cases where the reaction starts (i) from monomer molecules polymerizing to a defined number average chain length x¯n,eq and (ii) from monodisperse polymer molecules reacting with each other under the constrain that x¯n is the same at the beginning and the end of the reaction. In both cases we find that the nature of the activity coefficient has an important effect on the curvature of σ which may considerably differ from that of an ideal behavior.
Irreducible correlation functions of the Ŝ matrix in the coordinate representation: Application in calculating Lorentzian half-widths and shifts
Authors: Ma Q. , Tipping R. H. , Boulet C.
Published: January 2006

By introducing the coordinate representation, the derivation of the perturbation expansion of the Liouville Ŝ matrix is formulated in terms of classically behaved autocorrelation functions. Because these functions are characterized by a pair of irreducible tensors, their number is limited to a few. They represent how the overlaps of the potential components change with a time displacement, and under normal conditions, their magnitudes decrease by several orders of magnitude when the displacement reaches several picoseconds. The correlation functions contain all dynamical information of the collision processes necessary in calculating half-widths and shifts and can be easily derived with high accuracy. Their well-behaved profiles, especially the rapid decrease of the magnitude, enables one to transform easily the dynamical information contained in them from the time domain to the frequency domain. More specifically, because these correlation functions are well time limited, their continuous Fourier transforms should be band limited. Then, the latter can be accurately replaced by discrete Fourier transforms and calculated with a standard fast Fourier transform method. Besides, one can easily calculate their Cauchy principal integrations and derive all functions necessary in calculating half-widths and shifts. A great advantage resulting from introducing the coordinate representation and choosing the correlation functions as the starting point is that one is able to calculate the half-widths and shifts with high accuracy, no matter how complicated the potential models are and no matter what kind of trajectories are chosen. In any case, the convergence of the calculated results is always guaranteed. As a result, with this new method, one can remove some uncertainties incorporated in the current width and shift studies. As a test, we present calculated Raman Q linewidths for the N2–N2 pair based on several trajectories, including the more accurate “exact” ones. Finally, by using this new method as a benchmark, we have carried out convergence checks for calculated values based on usual methods and have found that some results in the literature are not converged.
First-principles calculation of geometry and anharmonic vibrational spectra of thioformamide and thioformamide-d2
Authors: Kowal Andrzej T.
Published: January 2006

The equilibrium geometry of thioformamide HCSNH2 has been determined at the MP2 and CCSD(T) electron correlation levels under Cs symmetry constraints using triple-zeta basis sets up to cc-pVTZ. All optimized planar structures are true minima on the potential-energy surface and are characterized by the C–N bond length within 1.353–1.343Å, C–S distances of 1.656–1.628Å, and NCS angle between 125.7° and 125.9°. The wave number of the NH2 out-of-plane wagging mode computed in the harmonic approximation shows stronger dependence on the basis set rather than the electron correlation level and varies from 85.9cm−1 at CCSD(T)∕cc-pVDZ level to 335cm−1 at MP2/aug-cc-pVTZ level. Anharmonic vibrational spectra of HCSNH2 and HCSND2 have been determined directly from the potential-energy surfaces computed at MP2 level in triple-zeta valence (TZV)(2df,2p) and TZV+(2df,2p) basis sets using vibrational self-consistent-field (VSCF) and correlation-corrected VSCF (CC-VSCF) methods. CC-VSCF wave numbers of fundamental, first overtone, and most intense combination transitions are reported for thioformamide and those of fundamentals for thioformamide-d2. The NH2 wagging (ν12) mode is strongly anharmonic and its fundamentals have been computed at 406.9cm−1[TZV(2df,2p)] and 399.5cm−1[TZV+(2df,2p)], which is remarkably close to the experimental energy of 393cm−1. Anharmonically computed fundamentals of this mode in thioformamide-d2, 299.7cm−1[TZV(2df,2p)] and 299.6cm−1[TZV+(2df,2p)], are only ∼7cm−1 higher than the transition energy (293cm−1) observed in the gas phase spectrum of HCSND2. The first overtone of the NH2 wagging mode of thioformamide (ν1202) has been calculated by CC-VSCF procedure at 830.8cm−1[TZV(2df,2p)] and 880.0cm−1[TZV+(2df,2p)], which implies “negative” (ν1202>2*ν1201) anharmonicity of this mode.
Evaluation of surface tension and Tolman length as a function of droplet radius from experimental nucleation rate and supersaturation ratio: Metal vapor homogeneous nucleation
Authors: Onischuk A. A. , Purtov P. A. , Baklanov A. M. , Karasev V. V. , Vosel S. V.
Published: January 2006

Zinc and silver vapor homogeneous nucleations are studied experimentally at the temperature from 600 to 725 and 870K, respectively, in a laminar flow diffusion chamber with Ar as a carrier gas at atmospheric pressure. The size, shape, and concentration of aerosol particles outcoming the diffusion chamber are analyzed by a transmission electron microscope and an automatic diffusion battery. The wall deposit is studied by a scanning electron microscope (SEM). Using SEM data the nucleation rate for both Zn and Ag is estimated as 1010cm−3s−1. The dependence of critical supersaturation on temperature for Zn and Ag measured in this paper as well as Li, Na, Cs, Ag, Mg, and Hg measured elsewhere is analyzed. To this aim the classical nucleation theory is extended by the dependence of surface tension on the nucleus radius. The preexponent in the formula for the vapor nucleation rate is derived using the formula for the work of formation of noncritical embryo [obtained by Nishioka and Kusaka [J. Chem. Phys. 96, 5370 (1992)] and later by Debenedetti and Reiss [J. Chem. Phys. 108, 5498 (1998)]] and Reiss replacement factor. Using this preexponent and the Gibbs formula for the work of formation of critical nucleus the dependence of surface tension on the radius RS of the surface of tension is evaluated from the nucleation data for above-mentioned metals. For the alkali metals and Ag the surface tension was determined to be a strong function of RS. For the bivalent metals (Zn, Hg, and Mg) the surface tension was independent of radius in the experimental range. A new formula for the Tolman length δ as a function of surface tension and radius RS is derived by integration of Gibbs-Tolman-Koenig equation assuming that δ is a monotonic function of radius. The formula derived is more correct than the Tolman formula and convenient for the elaboration of experimental data. Using this formula the values of δ are determined as a function of RS from the experimental nucleation data. It is determined that all the metals considered are characterized by strong dependence of δ on radius; for the bivalent metals δ changes sign.
Monte Carlo phase diagram for diblock copolymer melts
Authors: Matsen M. W. , Griffiths G. H. , Wickham R. A. , Vassiliev O. N.
Published: January 2006

A partial phase diagram is constructed for diblock copolymer melts using lattice-based Monte Carlo simulations. This is done by locating the order-disorder transition (ODT) with the aid of a recently proposed order parameter and identifying the ordered phase over a wide range of copolymer compositions (0.2⩽f⩽0.8). Consistent with experiments, the disordered phase is found to exhibit direct first-order transitions to each of the ordered morphologies. This includes the spontaneous formation of a perforated-lamellar phase, which presumably forms in place of the gyroid morphology due to finite-size and/or nonequilibrium effects. Also included in our study is a detailed examination of disordered cylinder-forming (f=0.3) diblock copolymers, revealing a substantial degree of pretransitional chain stretching and short-range order that set in well before the ODT, as observed previously in analogous studies on lamellar-forming (f=0.5) molecules.
Energetics of formation of TiGa3As4 and TiGa3P4 intermediate band materials
Authors: Palacios Pablo , Wahnón Perla , Pizzinato Sara , Conesa José C.
Published: January 2006

Using density functional theory quantum methods, total energy values and vibrational properties have been computed, and thermodynamic properties evaluated, for Ti-substituted GaAs and GaP, proposed as candidates for intermediate band photovoltaic cells. The calculations predict that the formation of these materials from the binary compounds implies an increase in total energy (that is ascribed largely to the change in coordination undergone by Ti, from six-fold to four-fold), and thus phase separation rather than mixed compound formation would be favored. However, the mentioned increase is not larger (for the arsenide case it is actually smaller) than that predicted for Mn-substituted GaAs, a material which has been experimentally made, and therefore the obtention of these Ti-substituted materials is expected to be feasible as well. Vibrational and disorder entropy contributions to the formation free energy of the ternary compounds have been also computed; they compensate partially for the total energy increase, and indicate that the thermodynamic feasibility of the materials synthesis improves for low Ti concentrations and high temperature conditions.
A comparative study of the polyaniline thin films produced by the cluster beam deposition and laser ablation methods
Authors: Lim Hyuna , Choi Jong-Ho
Published: January 2006

Polyaniline (PANI) thin films have been prepared by applying the novel neutral and ionized cluster beam deposition (NCBD and ICBD) methods and the pulsed laser deposition (PLD) technique to the PANI samples of half-oxidized emeraldine base (EB-PANI) and protoemeraldine base forms in a high-vacuum condition. Characterization of the oxidation states and structural changes of pristine and doped thin films has been performed by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and x-ray photoelectron spectroscopy. Spectroscopic measurements demonstrate that the dominant structure of NCBD and ICBD thin films corresponds to the reduced leucoemeraldine base state, whereas the chemical composition of PLD thin films depends critically on the laser fluence and the molecular weight of PANI target. The congruent deposition is only obtained for the PLD films deposited by the laser-induced decomposition of the low-molecular-weight targets in the low to intermediate fluence regime (below 100mJ∕cm2 with a pulse duration of 7ns). The surface morphology examined by atomic force microscopy measurements shows that the cluster and laser beams are effective in producing smooth, uniform polymeric thin films. After I2 and HCl doping, the electrical conductivities of the NCBD, ICBD, and particularly PLD thin films are increased significantly. The higher conductivity of PLD films is ascribed to higher amounts of quinoid di-imine doping sites in the EB-PANI state, and the overall structure-conductivity characteristics are consistent with the spectroscopic observations.
Drift of spiral waves controlled by a polarized electric field
Authors: Chen Jiang-Xing , Zhang Hong , Li You-Quan
Published: January 2006

The drift behavior of spiral waves under the influence of a polarized electric field is investigated in the light that both the polarized electric field and the spiral waves possess rotation symmetry. Numerical simulations of a reaction-diffusion model show that the drift velocity of the spiral tip can be controlled by changing the polarization mode of the polarized electric field and some interesting drift phenomena are observed. When the electric field is circularly polarized and its rotation follows that of the spiral, the drift speed of the spiral tip reaches its maximal value. On the contrary, opposite rotation between the spiral and electric field locks the drift of the spiral tip. Analytical results based on the weak deformation approximation are consistent with the numerical results. We hope that our theoretical results will be observed in experiments, such as the Belousov-Zhabotinsky reaction.
A full dimensional time-dependent wave packet study for the H4 four-center, collision induced dissociation, and single exchange reactions: Reaction probabilities for J=
Authors: Lu Yunpeng , Lee Soo-Y. , Zhang Dong H.
Published: January 2006

A time-dependent initial state selected wave packet method has been developed to study the H2(v1=10−11,j1=0)+H2′(v2=0,j2=0)→HH′+HH′ four-center (4C) reaction, and two other competing reactions: the H2+H2′→H+H+H2′ collision induced dissociation (CID) and the H2+H2′→H+HH′+H′ single exchange (SE) reaction, in full six dimensions. Initial state-specific total reaction probabilities for these three competing reactions are presented for total angular momentum J=0 and the effects of reagent vibration on reactions are examined. It is found that (a) the CID process is the dominant process over the whole energy range considered in this study, but the 4C and SE processes also have non-negligible probabilities; (b) the SE process has a lower threshold energy than the 4C process, but the SE probability increases slower than the 4C probability as collision energy increases; (c) the vibrational excitation of H2(v1) is much more efficient than translational motion for promoting these processes, in particular to the CID process.
Formation of regular nanoscale undulations on a thin polymer film imprinted by a soft mold
Authors: Suh Kahp Y. , Seo Soon Min , Yoo Pil J. , Lee Hong H.
Published: January 2006

We observed the formation of regular nanoscale undulations on a polystyrene film when imprinted by a soft poly(dimethylsiloxane) mold above the polymer’s glass transition temperature. The shape of the wave was reminiscent of a buckling wave frequently observed for a metal film supported on an elastomeric substrate. We derived a simple theoretical model based on an anisotropic buckling of the polymer film rigidly bound to a substrate, which agrees well with the experiment.
Screened exchange hybrid density-functional study of the work function of pristine and doped single-walled carbon nanotubes
Authors: Barone Verónica , Peralta Juan E. , Uddin Jamal , Scuseria Gustavo E.
Published: January 2006

We present a detailed study of the work function of pristine and doped single-walled carbon nanotubes (SWCNTs) using a novel screened exchange hybrid density functional. We find that SWCNTs with diameters larger than 0.9nm tend asymptotically and smoothly to the graphene limit of 4.6eV. On the other hand, the work function of narrow tubes exhibits a strong dependence on their diameter and chiral angle. Boron or nitrogen doping, with concentrations from 1% to 2%, not only changes the electronic behavior by introducing new states around the Fermi level, but also produces a significant change of the work function that can vary between 3.9 (N doping) and 5.2eV (B doping).
The equation for time-like extremal surfaces in Minkowski space R2+n
Authors: Kong De-Xing , Sun Qing-You , Zhou Yi
Published: January 2006

In this paper we investigate the equation for time-like extremal surfaces in the Minkowski space R2+n, and show that this kind of equation enjoys many interesting properties nonstrict hyperbolicity, constant multiplicity of eigenvalues, boundedness of characteristic propagation speeds, linear degeneracy of all characteristic fields, richness, etc. Without any smallness assumption of initial data, we give the necessary and sufficient condition on the global existence of classical solutions of the Cauchy problem. Based on this, we prove some global existence theorems on classical solutions of the Dirichlet problem and Neumann problem for this kind of equation. Finally, we present an explicit exact representation, involving two independent arbitrary functions of general solution.
Surface oxide relationships to band bending in GaN
Authors: Garcia Michael A. , Wolter Scott D. , Kim Tong-Ho , Choi Soojeong , Baier Jamie , Brown April , Losurdo Maria , Bruno Giovanni
Published: January 2006

A trend of increased near-surface valence band maximum band bending with increasing O∕Ga relative fraction was observed, extrapolating to 2.7eV±0.1eV for pristine GaN surfaces (0% O 1s peak area). This trend of apparent oxide overlayer coverage affecting the band bending linearly could lead to better understanding and characterization of oxidized GaN surfaces to control band bending for sensors or other devices.
Effect of current crowding on void propagation at the interface between intermetallic compound and solder in flip chip solder joints
Authors: Zhang Lingyun , Ou Shengquan , Huang Joanne , Tu K. N. , Gee Stephen , Nguyen Luu
Published: January 2006

We propose a kinetic model to describe a pancake-type void propagation in flip chip solder joints due to current crowding in electromigration. The divergence of the vacancy fluxes at the interface between the solder and Cu6Sn5 leads to void formation and propagation along the interface between them. Based on the continuity condition, the void growth velocity is calculated. The theoretical calculations are in reasonable agreement with the experimental results.
Strain dependence of Si–Ge interdiffusion in epitaxial Si∕Si1−yGey∕Si heterostructures on relaxed Si1−xGex substrates
Authors: Xia Guangrui , Olubuyide Oluwamuyiwa O. , Hoyt Judy L. , Canonico Michael
Published: January 2006

The strain dependence of Si–Ge interdiffusion in epitaxial Si∕Si1−yGey∕Si heterostructures on relaxed Si1−xGex substrates has been studied using secondary ion mass spectrometry, Raman spectroscopy, and simulations. At 800 and 880 °C, significantly enhanced Si–Ge interdiffusion is observed in Si∕Si1−yGey∕Si heterostructures (y=0.56, 0.45, and 0.3) with Si1−yGey layers under compressive strain of −1%, compared to those under no strain. In contrast, tensile strain of 1% in Si0.70Ge0.30 layer has no observable effect on interdiffusion in Si∕Si0.70Ge0.30∕Si heterostructures. These results are relevant to the device and process design of high mobility dual channel and heterostructure-on-insulator metal oxide semiconductor field effect transistors.
Growth and magnetic properties of epitaxial MnAs thin films grown on InP(001)
Authors: Yokoyama M. , Ohya S. , Tanaka M.
Published: January 2006

Epitaxial ferromagnetic MnAs thin films have been grown by molecular-beam epitaxy on semi-insulating InP(001) substrates. The MnAs c axis (MnAs[0001]) lies along the InP[1¯10] axis, and the easy magnetization axis is in-plane, along the MnAs[112¯0] axis, which is parallel to the InP[110] axis. The ferromagnetic transition temperature of the MnAs films on InP(001) was estimated to be 321 K. The structural and magnetic properties of MnAs thin films grown on InP(001) substrates are similar to those of type-A MnAs films grown on GaAs(001) substrates. The feasibility of growing monocrystalline ferromagnetic layers on InP(001) will open up the possibility of monolithic integration of magnetic functions with InP-based optoelectronics devices.
Reduced electronegativity difference as a factor leading to the formation of Al-based glassy alloys with a large supercooled liquid region of 50K
Authors: Louzguine-Luzgin Dmitri V. , Inoue Akihisa , Botta Walter José
Published: January 2006

The influence of the electronegativity difference among the constituent elements on the stability of the supercooled liquid in two Al-based glassy alloys is studied. A record-large value of the supercooled liquid region of about 50K is obtained based on the electronegativity difference concept within a certain composition range.
Vertical coupling of long-range surface plasmon polaritons
Authors: Won Hyong Sik , Kim Ki Cheol , Song Seok Ho , Oh Cha-Hwan , Kim Pill Soo , Park Suntak , Kim Sang In
Published: January 2006

We evaluated and demonstrated strong vertical-coupling characteristics of vertical directional couplers based on long-range surface plasmon polaritons (LRSPPs) at 1.55μm wavelength. Fundamental even and odd modes supported by LRSPP metal-stripe waveguides compete more strongly on vertical coupling structures than on lateral coupling structures, possibly leading to less power consumption for switching and to compactness in device length and width. LRSPP-based vertically coupled routing of signals can also be a powerful means of developing three-dimensional photonic integrated circuits and optical printed circuit boards.
Mapping of electrostatic potentials within core-shell nanowires by electron holography
Authors: Chung Jayhoon , Rabenberg Lew
Published: January 2006

Phase profiles within core-shell nanowires composed of intrinsic germanium cores and shells of germanium oxide and/or doped germanium were imaged using electron holography in a transmission electron microscope. Accurate mean inner potentials for germanium and its oxide were determined from phase data obtained from experimental electron holography with knowledge of the thickness profile of the nanowire. Using measured and simulated phase profiles, it was possible to determine the dopant concentration within a shell of doped germanium around an intrinsic germanium core. Measurement of mean inner potentials and dopant levels within semiconductor core-shell nanowires was demonstrated.
Enhancing photocatalytic activity by using TiO2–MgO core-shell-structured nanoparticles
Authors: Jung Hyun Suk , Lee Jung-Kun , Nastasi Michael , Kim Jeong-Ryeol , Lee Sang-Wook , Kim Jin Young , Park Jong-Sung , Hong Kug Sun , Shin Hyunho
Published: January 2006

Hygroscopic Mg(OH)2 gel was topotactically decomposed on TiO2 particle surfaces, resulting in highly nanoporous MgO-coated TiO2 particles. The highly hygroscopic and nanoporous MgO shell absorbed more water molecules and hydroxyl groups from the environment to yield an improved photocatalytic property of the core-shell particles as compared to the uncoated TiO2 counterpart.
Experimental evidence of plastic deformation instability in nanoscale Au∕Cu multilayers
Authors: Zhang G. P. , Liu Y. , Wang W. , Tan J.
Published: January 2006

Plastic deformation instability in Au∕Cu multilayers has been investigated as a function of individual layer thickness by nanoindentation and focused ion beam cross-sectional view techniques. Experimental results demonstrate that when the length scales of grains and individual layer thickness of the multilayered composite approach the nanometer regime, inhomogeneous shear banding becomes prevalent. The width of shear bands decreases with the decrease of these length scales. The extent of plastic deformation instability was characterized and the possible physical mechanism of the highly localized plastic deformation was explained.
Carbon-nanotube-based single-electron/hole transistors
Authors: Li Hong , Zhang Qing , Li Jingqi
Published: January 2006

Single-walled-carbon-nanotube (SWNT)-based single-electron/hole devices are fabricated with long SWNT channel surrounded by several short SWNTs on the electrodes. The channel current of the device is suggested to be controlled by the Schottky barriers, which are very sensitive to the electrostatic potential at the SWNT/electrode contacts. Coulomb blockade phenomena in the channel current below 70K suggest two-fold effects caused by single electron/hole charging the short SWNTs: (1) The charged short SWNTs have a significant characteristic of Coulomb blockade, and (2) the electrostatic potential of charged short SWNTs modify the Schottky barrier, and hence the channel current.
Nonradiative recombination effect on photoluminescence decay dynamics in GaInNAs∕GaAs quantum wells
Authors: Sun Z. , Xu Z. Y. , Yang X. D. , Sun B. Q. , Ji Y. , Zhang S. Y. , Ni H. Q. , Niu Z. C.
Published: January 2006

The influence of nonradiative recombination on the photoluminescence (PL) decay dynamics in GaInNAs∕GaAs quantum wells is studied by time-resolved photoluminescence under various excitation intensities. It is found that the PL decay process strongly depends on the excitation intensity. In particular, under the moderate excitation levels the PL decay curves exhibit unusual nonexponential behavior and show a convex shape. By introducing a new parameter of the effective concentration of nonradiative recombination centers into a rate equation, the observed results are well simulated. The cw PL data further demonstrate the nonradiative recombination effect on the optical properties of GaInNAs∕GaAs quantum wells.
Site specific Eu3+ stimulated emission in GaN host
Authors: Park J. H. , Steckl A. J.
Published: January 2006

We report the observation of site-specific Eu3+ stimulated emission in GaN:Eu laser structures. Two main Eu sites have been identified from emission peaks associated with the D05→F27 transition during above band gap optical pumping with a pulsed N2 laser (337nm): (a) Eux emitting at ∼620nm—present in short cavities (∼100μm), exhibiting stimulated (side) emission threshold and a fast decay time constant (30–35μs); (b) Euy emitting at ∼621nm—present in long cavities (∼7mm) and in surface emission, exhibiting no stimulated emission threshold and a slow decay time constant (150–250μs).
High conductivity of Ga-doped rock-salt ZnO under pressure: Hint on deep-ultraviolet-transparent conducting oxides
Authors: Segura A. , Sans J. A. , Errandonea D. , Martinez-García D. , Fages V.
Published: January 2006

This letter reports on transport and optical experiments under pressure in thin films of Ga-doped ZnO in both the wurtzite and rock-salt phases. The conductivity of heavily Ga-doped ZnO thin films is shown to decrease by only a factor of 2 in the wurtzite-to-rock-salt phase transition, occurring at about 11.5 GPa, while the optical gap increases from 4 to more than 5 eV. Ga-doped rock-salt ZnO is shown to behave as a deep-ultraviolet-transparent conducting oxide, with resistivity values as low as 10−3Ωcm. The analysis of Burstein–Moss shift and free carrier absorption in rock-salt ZnO yield an estimation of the electron-hole reduced effective mass and electronic dielectric constant. Given the similarity between the electronic structures of rock-salt ZnO under pressure and rock-salt MgxZn1−xO at ambient pressure, this alloy could be a good deep-ultraviolet-transparent conducting oxide.
Control of growth orientation for epitaxially grown ZnSe nanowires
Authors: Chan S. K. , Cai Y. , Wang N. , Sou I. K.
Published: January 2006

ZnSe nanowires (NWs) were grown on (111), (100), and (110)-oriented GaAs substrates by molecular-beam epitaxy via the vapor-liquid-solid reaction. The size dependence of NW growth orientation was studied by varying the Au catalyst size. Through detailed transmission electron microscopy studies, it was found that ⟨111⟩ orientation is the growth direction for NWs with size ⩾30nm, while NWs with size around 10nm prefer to grow along the ⟨110⟩ direction, with a small portion along the ⟨112⟩ direction. These observations have led to the realization of vertical ZnSe NWs with size around 10nm grown on a GaAs(110) substrate.
Ultrasonic atomization using MHz silicon-based multiple-Fourier horn nozzles
Authors: Tsai Shirley C. , Song Yu L. , Tsai Chen S. , Chou Yuan F. , Cheng Chih H.
Published: January 2006

Monodispersed droplets are produced in ultrasonic atomization using a microelectromechanical system-based three-Fourier horn 0.5MHz silicon nozzle 3.66×0.38×0.11cm3 in size. As water enters the 200μm×200μm central channel of the nozzle, a curved thin liquid film is maintained at the nozzle tip that vibrates at the resonance frequency of 486.5kHz, resulting in the formation of standing capillary waves on the free film surface. Temporal instability of these standing capillary waves occurs as the tip vibration amplitude exceeds a threshold, and a spray of droplets (mist) is produced. The measured droplet diameter of 7.0μm is in good agreement with the 6.7μm diameter calculated by 0.34 times the capillary wavelength.
Improved thermally stable ohmic contacts on p-GaN based on W2B
Authors: Voss L. , Khanna Rohit , Pearton S. J. , Ren F. , Kravchenko I.
Published: January 2006

The annealing temperature (25–800 °C) dependence of ohmic contact characteristics on p-GaN using a W2B∕Ti∕Au metallization scheme deposited by sputtering are reported. The contacts are rectifying in the as-deposited condition but become ohmic for annealing at ⩾500°C. A minimum specific contact resistivity of 1.7×10−3Ωcm−2 was obtained after annealing at 800 °C for 60 s. Higher annealing temperatures produced sharp increases in the resistivity of the GaN and irreproducible contact properties. However, the contact morphology was similar over the entire annealing range used here. Auger electron spectroscopy profiling showed the onset of Ti out-diffusion through the Au at 500 °C. By 800 °C the Ti was almost completely removed to the surface, where it became oxidized. These boride-based contacts have superior thermal stability to the more common Ni∕Au, whose morphology degrades significantly above 500 °C.
Ozone passivation of slow transient current collapse in AlGaN∕GaN field-effect transistors: The role of threading dislocations and the passivation mechanism
Authors: DiSanto D. W. , Sun H. F. , Bolognesi C. R.
Published: January 2006

Current collapse in AlGaN∕GaN field-effect transistors subjected high rf drive levels and/or to bias stresses is attributed to the presence of surface trapping levels whose nature remains to be identified. Although current collapse manifestations can be alleviated with various surface films, the exact passivation mechanism remains a matter of debate. We show that slow transient current collapse can be eliminated by a short ozone exposure, unambiguously tying current collapse to the sample surface, without invoking strain or dielectric encapsulation arguments. We assert that the surface states responsible for slow collapse arise where dislocations intersect the sample surface, and propose an alternative current collapse mechanism wherein individual dislocation lines result in multiple discrete virtual gates that locally deplete the transistor channel access regions.
Effect of hydrostatic pressure on the dc characteristics of AlGaN∕GaN heterojunction field effect transistors
Authors: Liu Y. , Ruden P. P. , Xie J. , Morkoç H. , Son K.-A.
Published: January 2006

We report the effect of compressive hydrostatic pressure on the current-voltage characteristics of AlGaN∕GaN heterojunction field effect transistors (HFETs) on a sapphire substrate. The drain current increases with hydrostatic pressure and the maximum relative increase occurs when the gate bias is near threshold and drain bias is slightly larger than saturation bias. The increase of the drain current is associated with a pressure induced shift of the threshold voltage by −8.0mV∕kbar that is attributed to an increase of the polarization charge density at the AlGaN∕GaN interface due to the piezoelectric effect. The results demonstrate the considerable potential of AlGaN∕GaN HFETs for strain sensor applications.
Microdischarge-assisted ignition of dielectric-barrier high-pressure glow discharges
Authors: Shin Jichul , Raja Laxminarayan L.
Published: January 2006

The ignition characteristics of dielectric-barrier high-pressure glow (DB-HPG) discharges in the presence of dc microdischarges are studied for pure helium and pure nitrogen working gases. In the presence of an array of microdischarges integrated with one of the DB-HPG electrodes, a substantial reduction of DB-HPG ignition voltage is observed for both working gases. The discharge structure within the DB-HPG volume gap is localized near the microdischarge holes when the DB-HPG first turns on in the presence of microdischarges, but subsequently expands to cover the entire volume at higher voltages for the pressures studied. The helium discharge is generally more uniform than the nitrogen gas. Our studies indicate that the localized discharge has a glow-like character rather than a Townsend- or streamer-like one.
Effects of temperature fluctuation on highly dispersive photonic crystal fibers
Authors: Jiang Yongqiang , Chen Xiaonan , Howley Brie , Chen Maggie Y. , Chen Ray T.
Published: January 2006

Chromatic dispersion of highly dispersive photonic crystal fibers (PCFs) is theoretically simulated and experimentally measured as a function of temperature. We have theoretically confirmed that PCFs designed at highly dispersive region show stronger temperature dependence than conventional telecommunication fibers and dispersion compensation fibers due to phase matching wavelength shift and large dispersion slope. For a fabricated highly dispersive PCF, the variation of the dispersion is measured to be around +0.28%∕°C from 21to80°C, and around +0.21%∕°C from 21to50°C at an optical wavelength around 1550nm.