bluuebunny/crossref_metadata_2025 huggingface dataset:
Comment on “A simplified model to calculate the higher surface energy of free‐standing nanocrystals” [phys. stat. sol. (b) 242, No. 8, R76–R78 (2005)]
Authors: Qi W. H.
Published: November 2005

In the Rapid Research Letter by Dan Xie et al. [phys. stat. sol. (b) 242, R76–R78 (2005)], a method is developed to calculate the higher surface energy of free‐standing nanoparticles. However, due to errors in the formula manipulation and improper calculation of the surface‐to‐volume ratio, the surface energy of nanoparticles is overestimated. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reply to “Comment on ‘A simplified model to calculate the higher surface energy of free‐standing nanocrystals’” [phys. stat. sol. (b) 242, No. 15, R129–R130 (2005)]
Authors: Xie Dan , Wang Mingpu , Cao Lingfei
Published: November 2005

Some potential problems in our recent letter [D. Xie et al., phys. stat. sol. (b) 242, R76 (2005)], which have been pointed out by a comment [W. H. Qi, phys. stat. sol. (b) 242, R129 (2005)] are discussed in detail. Furthermore, the formation enthalpies of nanocrystals are calculated by using the equation of surface energies established in the mentioned letter, and the fact that the predicted formation enthalpy values are consonant with the corresponding experimental results of Mo and W nanocrystals verifies the appearance of the higher surface energy of nanocrystals in return. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
DFT study of a single F center in cubic SrTiO3 perovskite
Authors: Evarestov R. A. , Kotomin E. A. , Zhukovskii Yu. F.
Published: November 2005

Various properties of a cubic phase of SrTiO3 perovskite containing single F centers (neutral oxygen vacancies), including energies of their formation and migration, were simulated using different formalisms of density functional theory (DFT) as implemented into CRYSTAL‐2003 and VASP computer codes. The lattice relaxation around the F center was found to be sensitive to both shape and size of supercells used. The larger the supercell, the closer the defect energy level in the bandgap lies to the conduction band bottom. It approaches the optical ionization energy of 0.49 eV for 270‐ and 320‐atom supercells, where the distance between neighboring defects increases up to four lattice constants. The defect bandwidth decreases for these supercells down to 0.02 eV, i.e., the defect–defect interaction becomes negligible. Thus, the two different first‐principles periodic approaches combined provide results that are converged with respect to the supercell size and correspond to a single defect limit. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Measurement of sulfur isotope composition (δ34S) by multiple‐collector thermal ionization mass spectrometry using a 33S‐36S double spike
Authors: Mann Jacqueline L. , Kelly W. Robert
Published: November 2005

A new analytical technique is described for the determination of δ34S that is comparable to or better than modern gas source mass spectrometry in precision and accuracy, but requires about a factor of 10 less sample. The technique is based on the production of singularly charged arsenic sulfide molecular ions (AsS+) by thermal ionization using silica gel as an emitter and combines multiple‐collector thermal ionization mass spectrometry (MC‐TIMS) with a 33S‐36S double spike to correct instrumental fractionation. Three international sulfur standards (IAEA‐S‐1, IAEA‐S‐2, and IAEA‐S‐3) were measured to evaluate the precision and accuracy of the new technique and to evaluate the consensus values for these standards. Two different double spike preparations were used. The δ34S values (reported relative to Vienna Canyon Diablo Troilite (VCDT), (δ34S (‰) = ([((34S/32S)sample/(34S/32S)VCDT − 1) × 1000]), 34S/32SVCDT = 0.0441626) determined were −0.32 ± 0.04‰ (1σ, n = 4) and −0.31 ± 0.13‰ (1σ, n = 8) for IAEA‐S‐1, 22.65 ± 0.04‰ (1σ, n = 7) and 22.60 ± 0.06‰ (1σ, n = 5) for IAEA‐S‐2, and −32.47 ± 0.07‰ (1σ, n = 8) for IAEA‐S‐3. The amount of natural sample used for these analyses ranged from 0.40 to 2.35 µmol. Replicate determinations of each standard showed less than 0.5‰ variability (IAEA‐S‐1 <0.4‰, IAEA‐S‐2 <0.2‰, and IAEA‐S‐3 <0.2‰). Because the technique is based on thermal ionization of AsS+, and As is mononuclidic, corrections for interferences or for scale contraction/expansion are not required. The availability of MC‐TIMS instruments in laboratories around the world makes this technique immediately available to a much larger scientific community who require highly accurate and precise measurements of sulfur. Published in 2005 by John Wiley & Sons, Ltd.
Direct infusion mass spectrometry as a fingerprint of protein‐binding media used in works of art
Authors: Peris‐Vicente J. , Simó‐Alfonso E. , Gimeno Adelantado J. V. , Doménech Carbó M. T.
Published: November 2005

A direct infusion mass spectrometry method for the characterization of proteinaceous glues from binding media used in pictorial works of art prior to conservation or restoration treatment is proposed. Amino acids are released by acid hydrolysis and dissolved in a mixture of acidic water and ethanol. This mixture is directly infused into a mass spectrometer without any derivatization. The mass spectrometer is operated in positive ion electrospray mode (ESI‐MS) to yield [M+H]+ ions for the amino acids. Relative amounts of each amino acid are calculated for each protein (beef and porcine gelatines, albumin, casein and egg). The analyzed proteins were satisfactorily distinguished. The method is easy and fast, and shows good sensitivity and resolution. The proposed method has been successfully applied to artistic samples from items of the cultural heritage of Valencia (Spain). Copyright © 2005 John Wiley & Sons, Ltd.
Liquid chromatography/mass spectrometric analysis of rat samples for in vivo metabolism and pharmacokinetic studies of ginsenoside Rh2
Authors: Qian Tianxiu , Cai Zongwei , Wong Ricky N. S. , Jiang Zhi‐Hong
Published: November 2005

In vivo metabolism and pharmacokinetic studies on rat were conducted for ginsenoside Rh2, one of the components from ginseng that shows promise of anticancer activity. Liquid chromatography/mass spectrometry (LC/MS) and tandem mass spectrometry (MS/MS) with electrospray ionization were used to determine Rh2 and its metabolites in rat plasma, urine and feces. An average half‐life of 16 min in plasma was obtained after intravenous administration to male Sprague‐Dawley rats at 5 mg/kg. No Rh2 was detected in plasma samples collected from 0 to 24 h following oral administration at 100 mg/kg, and only 0.12–0.25% of the dosed amount was found in the feces samples collected from 0 to 48 h after oral administration at 100 mg/kg. Three metabolites of Rh2 were detected in the feces samples. Oxygenation and deglycosylation were found to be the major metabolic pathways of Rh2. Intense metabolism, rather than excretion, appears to be the reason for the fast clearance of this ginsenoside. Copyright © 2005 John Wiley & Sons, Ltd.
Resonant inelastic x‐ray scattering from highly correlated dysprosium compounds
Authors: Zhou K. J. , Cui M. Q. , Hua W. , Zhao Y. D. , Huang Y. Y.
Published: November 2005

Dy2O3 and Dy metal's resonant inelastic x‐ray scattering (RIXS) spectra were measured in the Beijing Synchrotron Radiation Facility. As a bulk sensitive probe and two‐photon process, RIXS provides more information on the electronic structure of matter. In this full RIXS experiment, the 2p64fn→ 2p54fn5d1 (2p54fn + 15d0) → 2p63d94fn5d1 (2p63d94fn + 15d0) channel of two samples (Dy2O3 and Dy metal) was studied. Further comparison shows that there are many differences in the RIXS spectra. Dy metal has only a single resonance and its 5d band is broader than that of Dy2O3. In the resonant regime, it has a lower final state energy, whereas in the non‐resonant regime it exceeds Dy2O3. This causes a broader bandwidth of the main final state B and a narrower bandwidth in the resonant and non‐resonant regime. The pre‐edge structure in Dy L3 absorption spectra was also resolved using RIXS, which cannot be seen in conventional XAS owing to 2p core hole lifetime broadening. Copyright © 2005 John Wiley & Sons, Ltd.
Refinement and retrenchment for programming language data types
Authors: Beckert Bernhard , Schlager Steffen
Published: November 2005

Refinement is a well-established and accepted technique for the systematic development of correct software systems. However, for the step from already refined specification to implementation, a correct refinement is often not possible because the data types used in the specification respectively the implementation language differ. In this paper, we discuss this problem and its consequences, using the integer data types of Java as an example, which do not correctly refine the mathematical integers ℤ. We present a solution, which can be seen as a generalisation of refinement and a variant of retrenchment. It has successfully been implemented as part of the KeY software verification system.
A computational study of creativity in design: The role of society
Authors: SOSA RICARDO , GERO JOHN S.
Published: November 2005

Studies of creativity have tended to focus on isolated individuals, under the assumption that it can be defined as a characteristic of an extraordinary person, product, or process. Existing computational models of creative behavior have inherited this emphasis on independent generative processes. However, an increasing multidisciplinary consensus regards creativity as a systems property, and extends the focus of inquiry to include the interaction between generative individuals and evaluative social groups. To acknowledge the complementarity of evaluative processes by social groups, experts, and peers, this paper presents experimentation with a framework of design as a social activity. This model is used to inspect phenomena associated with creativity in the interaction between designers and their societies. In particular, this paper describes the strength of social ties as a mechanism of social organization, and explores its potential relation to creativity in a computational social simulation. These experiments illustrate ways in which the role of designers as change agents of their societies can be largely determined by how the evaluating group self-organizes over time. A key potential implication is that the isolated characteristics of designers may be insufficient to formulate conclusions about the nature and effects of their behavior. Instead, causality could be attributed to situational factors that define the relationship between designers and their evaluators.
Feature modeling using a grammar representation approach
Authors: OSTROSI E. , FERNEY M.
Published: November 2005

In intelligent computer-aided design the concept of intelligence is
related to that of integration. Using feature-based computer-aided design
models is thought to make a complete integration. This paper presents a
feature recognition approach based on the use of a feature grammar. Given
the complexity of feature recognition in interactions, the basic idea of
the approach is to find the latent and logical structure of features in
interaction. The approach includes five main phases. The first phase,
called regioning, identifies the potential zones for the birth of
features. The second phase, called virtual extension, builds links and
virtual faces. The third phase, called structuring, transforms the region
into a structure compatible with the structure of the features represented
by the feature grammar. The fourth phase, called Identification,
identifies the features in these zones. The fifth phase, called modeling,
represents the model by features. The feature modeling system software is
developed based on this approach.
Shape decompositions and their algebras
Authors: KRSTIC DJORDJE
Published: November 2005

Shapes play an important role in many human activities, but are rarely seen in their natural form as raw and unanalyzed. Rather, shapes come analyzed, structured in terms of their certain parts, forming shape decompositions. Different kinds of shape decompositions are developed, the most interesting among which are the decompositions that could be used as shape approximations. Two kinds of such decompositions,discreteandbounded, are examined in greater detail. Computations with shapes conducted in the framework of shape grammars and related shape algebras have been standard for over 3 decades. Similar computations are possible with analyzed shapes or shape decompositions. Different algebras to compute with shape decompositions are developed and compared to the shape algebras. The measure of their agreement determines how well the shapes are approximated by their decompositions.
Shouting at the Wall: Self-Determination and the Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory
Authors: GAREAU JEAN-FRANÇOIS
Published: November 2005

This article appraises the impact of the Advisory Opinion of 7 July 2004 on the development of self-determination as a legal principle. The plight of the Palestinians being widely understood as a textbook self-determination struggle, the Court had to address the issue in its examination of the case at hand. Self-determination left an indelible mark upon the Opinion, from the decision to allow Palestine to participate, through the use of the principle as applicable law, to the elucidation of the violations and the erga omnes character of the obligations breached. The article examines the Court's positions, which, however sparsely elaborated, may have serious repercussions on the understanding of the principle and on its handling in future judicial proceedings.
The Special Court for Sierra Leone and the Immunity of Taylor: The Arrest Warrant Case Continued
Authors: NOUWEN SARAH M. H.
Published: November 2005

In its Taylor decision the Special Court for Sierra Leone denied immunity ratione personae to the, at the time of the indictment, President of Liberia. This article first analyzes the legal reasoning of that decision. The Court's finding that it is an international court is approved; the consequence it attaches to that finding is criticized. The decision is then presented as an illustration of the negative consequences of relying upon controversial elements of the ICJ's Arrest Warrant case. It is suggested that instead of the distinction between national and international courts, the difference between criminal responsibility and procedural immunity could have been the basis for the reasoning of the ICJ and Special Court.
Coastal water source of short‐lived halocarbons in New England
Authors: Zhou Yong , Varner Ruth K. , Russo Rachel S. , Wingenter Oliver W. , Haase Karl B. , Talbot Robert , Sive Barkley C.
Published: November 2005

Short‐lived halocarbon tracers were used to investigate marine influences on air quality in a coastal region of New England. Atmospheric measurements made at the University of New Hampshire's Observing Station at Thompson Farm (TF) in Durham, New Hampshire, indicate that relatively large amounts of halocarbons are emitted from local estuarine and coastal oceanic regions. Bromine‐containing halocarbons of interest in this work include bromoform (CHBr3) and dibromomethane (CH2Br2). The mean mixing ratios of CHBr3 and CH2Br2 from 11 January to 5 March 2002 were 2.6 pptv and 1.6 pptv, and from 1 June to 31 August 2002 mean mixing ratios were 5.9 pptv and 1.4 pptv, respectively. The mean mixing ratio of CHBr3 was not only highest during summer, but both CHBr3 and CH2Br2 exhibited large variability in their atmospheric mixing ratios during this season. We attribute the greater variability to increased production combined with faster atmospheric removal rates. Other seasonal characteristics of CHBr3 and CH2Br2 in the atmosphere, as well as the impact of local meteorology on their distributions at this coastal site, are discussed. Tetrachloroethene (C2Cl4) and trichloroethene (C2HCl3) were used to identify time periods influenced by urban emissions. Additionally, measurements of CHBr3, CH2Br2, C2Cl4, methyl iodide (CH3I), and ethyl iodide (C2H5I) were made at TF and five sites throughout the nearby Great Bay estuarine area between 18 and 19 August 2003. These measurements were used to elucidate the effect of the tidal cycle on the distributions of these gases. The mean mixing ratios of CHBr3, CH2Br2, CH3I, and C2H5I were ∼82%, 46%, 14%, and 17% higher, respectively, near the coast compared to inland sites, providing evidence for a marine source of short‐lived halocarbons at TF. Correlation between the tidal cycle and atmospheric concentrations of marine tracers on the night of 18 August 2003 showed that the highest values for the brominated species occurred ∼2–3 hours after high tide. Emission fluxes of CHBr3, CH2Br2, CH3I, and C2H5I on this night were estimated to be 26 ± 57, 4.7 ± 5.4, 5.9 ± 4.6, and 0.065 ± 0.20 nmol m−2 h−1, respectively. Finally, the anthropogenic source strength of CHBr3 was calculated to determine its impact on atmospheric levels observed in this region. Although our results indicate that anthropogenic contributions could potentially range from 15 to 60% of the total dissolved CHBr3 in the Great Bay, based on the observed ratio of CH2Br2/CHBr3 and surface seawater measurements in the Gulf of Maine, it appears unlikely that anthropogenic activities are a significant source of CHBr3 in the region.
High‐pressure sound velocities and elasticity of aluminous MgSiO3 perovskite to 45 GPa: Implications for lateral heterogeneity in Earth's lower mantle
Authors: Jackson Jennifer M. , Zhang Jianzhong , Shu Jinfu , Sinogeikin Stanislav V. , Bass Jay D.
Published: November 2005

Brillouin scattering measurements on aluminous magnesium silicate perovskite, arguably the most abundant phase in Earth, have been performed to 45 GPa in a diamond anvil cell at room temperature, using methanol‐ethanol‐water and neon as pressure transmitting media. The experiments were performed on a polycrystalline sample of aluminous MgSiO3 perovskite containing 5.1 ± 0.2 wt.% Al2O3. The pressure derivatives of the adiabatic bulk (K0S) and shear (μ0S) moduli are 3.7 ± 0.3 and 1.7 ± 0.2, respectively. These measurements allow us to evaluate whether the observed lateral variations of seismic wave speeds in Earth's lower mantle are due at least in part to a chemical origin. Our results indicate that a difference in the aluminum content of silicate perovskite, reflecting a variation in overall chemistry, is a plausible candidate for such seismic heterogeneity.
Frequency‐dependent sites amplifications evaluated from well‐logging data in central Taiwan
Authors: Huang Ming‐Wey , Wang Jeen‐Hwa , Hsieh Hung‐Hao , Wen Kuo‐Liang , Ma Kuo‐Fong
Published: November 2005

Based on the quarter‐wavelength approximation by Boore and Joyner (1997), the frequent‐dependent site amplifications at 87 free‐field strong‐motion stations in central Taiwan from borehole data are evaluated. Results show that the amplifications increase with frequency, and the amplification is larger at the sites in the Western Plain with Holocene alluvium than at those in the Western Foothill with Pleistocene and Miocene formations.
Stable isotopes in East African precipitation record Indian Ocean zonal mode
Authors: Vuille M. , Werner M. , Bradley R. S. , Chan R. Y. , Keimig F.
Published: November 2005

Observational stable isotope data and model simulations show that the δ18O composition of precipitation in East Africa is closely related to the coupled ocean‐atmosphere system over the Indian Ocean. During the rainy seasons δ18O is a very sensitive recorder of the Indian Ocean Zonal Mode (IOZM). The link between δ18O and the IOZM is established through adjustments in the large‐scale overturning circulation over the Indian Ocean and associated changes in convective activity and precipitation over East Africa. The IOZM is recorded as significant departures in δ18O not only over East Africa but as a dipole mode with opposite sign to the east and west of the Indian Ocean.
Dynamic transfer of rupture across differently oriented segments in a complex 3‐D fault system
Authors: Aochi Hideo , Scotti Oona , Berge‐Thierry Catherine
Published: November 2005

We simulate spontaneous dynamic propagation of rupture across two adjacent fault segments, subject to a triaxial compressive stress regime. These segments have different orientations and hence different focal mechanisms (vertical strike‐slip and dipping thrust). Numerical simulations, using a BIEM (boundary integral equation method), have revealed that, under a typical triaxial homogeneous compressive stress regime where the magnitude of the intermediate principal stress lies halfway between those of the maximum and minimum ones, ruptures of different focal mechanisms are not likely to occur simultaneously in a single rupture event. Propagation of rupture from a vertical strike‐slip fault segment to a pure dip‐slip (normal/reverse) fault segment is possible only when the stress field is close to uniaxial compression, or when the intermediate stress magnitude is close either to the minimum or the maximum one. These findings are useful for evaluating possible earthquake scenarios along fault systems with complex 3D geometries.
Seasonal prediction of Danube flow variability based on stable teleconnection with sea surface temperature
Authors: Rimbu N. , Dima M. , Lohmann G. , Musat I.
Published: November 2005

It is shown that spring Danube flow anomalies are significantly related to winter SST anomalies from several key regions. These areas are identified through stable teleconnections between flow and SST. A forecast scheme is developed and applied to predict flow anomalies using SST anomalies from these key regions. Small potential predictability of winter flow anomalies from autumn sea surface temperature anomalies was also detected. The predictability of the flow anomalies from summer and autumn using SST from the previous seasons is limited by the instability of teleconnections.
Thermal observations of gas pistoning at Kilauea Volcano
Authors: Johnson Jeffrey B. , Harris Andrew J. L. , Hoblitt Richard P.
Published: November 2005

Data acquired by three continuously recording thermal infrared thermometers situated on the north rim of Pu`u `O`o Crater at Kilauea Volcano during 2002 revealed episodes of periodic thermal pulses originating from a degassing vent on the crater floor. These thermal pulses are interpreted as gas release (jetting events) associated with gas pistoning, a mechanism observed previously at both Mauna Ulu and Pu`u `O`o. During a 35‐day‐long period spanning June and July 2002, gas pistoning was frequently the dominant mode of gas release, with as many as several hundred pulses occurring in uninterrupted series. On other days, degassing alternated between periods of quasi‐continuous gas jetting and intervals of gas pistoning that contained a few to a few dozen pulses. Characteristic time intervals between pistoning events ranged from 2 up to 7 min. We identify three types of pistoning. Type 1 involves emission of lava, followed by gas jetting and drain back; type 2 is the same but the elevated position of the vent does not allow postjet drain back; and type 3 involves gas jetting only with no precursory lava flow. To explain gas pistoning, we apply a model whereby a stagnant cap of degassed magma develops in the conduit below the vent. Gas bubbles rise through the magma column and collect under the cap. The collective buoyancy of these bubbles pushes the cap upward. When the cap reaches the surface, it erupts from the vent as a lava flow. Unloading of the conduit magma in this way results in an abrupt pressure drop (i.e., the overburden felt by the bubbles is reduced), causing explosive gas expansion in the form of gas jetting from the vent. This terminates the event and lava drains back into the conduit to start the cycle anew. In the case where there is no surface lava emission or drain back, the cap instead pushes into and spreads out within a subsurface cavity. Again, this unloads the conduit magma and terminates in explosive gas release. Once gas is expelled, lava in the cavity is free to drain back. We hypothesize that pistoning is a stable mode of degassing for low‐viscosity basaltic magmas with appropriate conduit geometries and volatile supply rates.
Four‐year aerosol observations with a Raman lidar at Thessaloniki, Greece, in the framework of European Aerosol Research Lidar Network (EARLINET)
Authors: Amiridis V. , Balis D. S. , Kazadzis S. , Bais A. , Giannakaki E. , Papayannis A. , Zerefos C.
Published: November 2005

Regular aerosol extinction and backscatter measurements using a UV Raman lidar have been performed from January 2001 to December 2004 at Thessaloniki, Greece (40.5°N, 22.9°E), in the framework of the European Aerosol Research Lidar Network (EARLINET). Profiles of the aerosol extinction coefficient, backscatter coefficient, and extinction‐to‐backscatter ratio (so‐called “lidar ratio”) were acquired under nighttime conditions and have been used for statistical investigations. The statistical analysis was made both for the planetary boundary layer and for the free troposphere. It was found that the 4‐year mean boundary layer particle optical depth at 355 nm was 0.44 ± 0.18, and the total aerosol optical depth was 0.63 ± 0.27. Free tropospheric particles account on the average for 30% of the total aerosol optical depth, ranging from 5% (clean free troposphere conditions) to 55% (mainly Saharan dust events). For the cases examined, the integral of the lidar‐derived extinction coefficient was in good agreement with colocated aerosol optical depth measurements at 355 nm obtained with a Brewer spectroradiometer. The mean value of the lidar ratio at 355 nm derived, for the period of measurements at Thessaloniki, was 40 sr with a standard deviation of 21 sr. Mean height profiles of the particle lidar ratio, extinction, and backscatter coefficients are shown along with their seasonal dependence, showing a significant seasonal variability in the free troposphere. An analysis of the data using back trajectories showed also a dependence of the aerosol optical depth and the lidar ratio on the origin of the air mass, with higher values mostly corresponding to air masses originating from the northeast Balkans and eastern Europe.
Phase-space reaction network on a multisaddle energy landscape: HCN isomerization
Authors: Li Chun-Biu , Matsunaga Yasuhiro , Toda Mikito , Komatsuzaki Tamiki
Published: November 2005

By using the HCN/CNH isomerization reaction as an illustrative vehicle of chemical reactions on multisaddle energy landscapes, we give explicit visualizations of molecular motions associated with a straight-through reaction tube in the phase space inside which all reactive trajectories pass from one basin to another, with eliminating recrossing trajectories in the configuration space. This visualization provides us with a chemical intuition of how chemical species “walk along” the reaction-rate slope in the multidimensional phase space compared with the intrinsic reaction path in the configuration space. The distinct nonergodic features in the two different HCN and CNH wells can be easily demonstrated by a section of Poincaré surface of section in those potential minima, which predicts in a priori the pattern of trajectories residing in the potential well. We elucidate the global phase-space structure which gives rise to the non-Markovian dynamics or the dynamical correlation of sequential multisaddle chemical reactions. The phase-space structure relevant to the controllability of the product state in chemical reactions is also discussed.
Upconversion luminescence, intensity saturation effect, and thermal effect in Gd2O3:Er3,Yb3+ nanowires
Authors: Lei Yanqiang , Song Hongwei , Yang Linmei , Yu Lixin , Liu Zhongxin , Pan Guohui , Bai Xue , Fan Libo
Published: November 2005

In this paper, the upconversion luminescent properties of Gd2O3:Er3+,Yb3+ nanowires as a function of Yb concentration and excitation power were studied under 978-nm excitation. The results indicated that the relative intensity of the red emission (F9∕24-I15∕24) increased with increasing the Yb3+ concentration, while that of the green emission (S3∕24∕H11∕22-I15∕24) decreased. As a function of excitation power in ln-ln plot, the green emission of S3∕24-I15∕24 yielded a slope of ∼2, while the red emission of F9∕24-I15∕24 yielded a slope of ∼1. Moreover, the slope decreased with increasing the Yb3+ concentration. This was well explained by the expanded theory of competition between linear decay and upconversion processes for the depletion of the intermediate excited states. As the excitation power density was high enough, the emission intensity of upconversion decreased due to thermal quenching. The thermal effect caused by the exposure of the 978-nm laser was studied according to the intensity ratio of H11∕22-I15∕24 to S3∕24-I15∕24. The practical sample temperature at the exposed spot as a function of excitation power and Yb3+ concentration was deduced. The result indicated that at the irradiated spot (0.5×0.5mm2) the practical temperature considerably increased.
Why is hydrofluoric acid a weak acid?
Authors: Ayotte Patrick , Hébert Martin , Marchand Patrick
Published: November 2005

The infrared vibrational spectra of amorphous solid water thin films doped with HF at 40K reveal a strong continuous absorbance in the 1000–3275cm−1 range. This so-called Zundel continuum is the spectroscopic hallmark for aqueous protons. The extensive ionic dissociation of HF at such low temperature suggests that the reaction enthalpy remains negative down to 40K. These observations support the interpretation that dilute HF aqueous solutions behave as weak acids largely due to the large positive reaction entropy resulting from the structure making character of the hydrated fluoride ion.
Effect of heavy boron doping on pressure-induced phase transitions in single-crystal silicon
Authors: Yan X. Q. , Huang X. M. , Uda S. , Chen M. W.
Published: November 2005

The influence of applied loads and loading/unloading rates on pressure-induced phase transitions in lightly and heavily boron-doped silicon was systematically investigated. The resultant phases were plotted into two-dimensional maps with applied loads and loading/unloading rates as the coordinate axes. The formation region of the amorphous phase in the heavily boron-doped silicon was found to be much larger than that in the lightly boron-doped one, suggesting that heavy boron doping promotes the amorphization in silicon.
Dislocation loops in silicon-germanium alloys: The source of interstitials
Authors: Crosby R. T. , Jones K. S. , Law M. E. , Radic L. , Thompson P. E. , Liu J.
Published: November 2005

The relationships between extended defect evolution and boron diffusion in Si0.77Ge0.23 have been investigated. A SiGe structure was grown by molecular beam epitaxy with a 3×1018atoms∕cm3 boron marker layer positioned 0.50μm below the surface. Samples were ion implanted with 60 keV Si+ at a dose of 1×1014atoms∕cm2 and subsequently annealed at 750 °C for various times. The evolution of extended defects in the near surface region was monitored with plan-view transmission electron microscopy. Secondary ion mass spectroscopy concentration profiles facilitated the characterization of boron diffusion. Boron experiences transient enhanced diffusion regulated by the dissolution of dislocation loops. The maximum diffusion enhancement in Si0.77Ge0.23 is less than that observed in pure Si.
Evidence for oxygen vacancy inducing spontaneous normal-relaxor transition in complex perovskite ferroelectrics
Authors: Deng Guochu , Li Guorong , Ding Aili , Yin Qingrui
Published: November 2005

The relaxor ferroelectrics—0.3Pb(Zn1∕3Nb2∕3)O3–0.7(Pb,La)(Zr,Ti)O3—have been produced by sintering in reductive nitrogen ambient and postannealing in oxygen ambient. The two kinds of specimens exhibited great differences in the conductivity as a function of temperature, which indicated a high concentration of oxygen vacancies in the as-sintered specimen. On the other hand, this specimen underwent an evident spontaneous normal-relaxation transition, whereas the as-annealed one did not. The corresponding reason has been analyzed on the basis of the facts, which provide some evidence that the interior stresses due to oxygen deficiency induce the spontaneous normal-relaxor transition in the specimen sintered in reductive ambient.
Efficient spin relaxation in InGaN∕GaN and InGaN∕GaMnN quantum wells: An obstacle to spin detection
Authors: Chen W. M. , Buyanova I. A. , Nishibayashi K. , Kayanuma K. , Seo K. , Murayama A. , Oka Y. , Thaler G. , Frazier R. , Abernathy C. R. , Ren F. , Pearton S. J. , Pan C.-C. , Chen G.-T. , Chyi J.-I.
Published: November 2005

Transient magneto-optical spectroscopy of InGaN∕GaN and InGaN∕GaMnN quantum wells reveals a spin relaxation process with a characteristic time of 50 ps. We show that the observed spin relaxation is mediated by spin flips of individual carriers rather than by direct exciton spin flips, and is proposed to occur near the bottom of the exciton band (K=0). Nearly complete thermalization between spin sublevels of the excitons, observed immediately after the pulsed photoexcitation, is attributed to even faster spin relaxation of photogenerated hot carriers/excitons accompanying momentum and energy relaxation at high K vectors.
High-performance organic thin-film transistors with metal oxide/metal bilayer electrode
Authors: Chu Chih-Wei , Li Sheng-Han , Chen Chieh-Wei , Shrotriya Vishal , Yang Yang
Published: November 2005

We demonstrate bilayer source-drain (S-D) electrodes for organic thin film transistors (OTFT). The bilayer consists of a transition metal oxide (MoO3,WO3, or V2O5) layer and a metal layer. The metal oxide layer, directly contacting the organic semiconducting layer, serves as the charge-injection layer. The overcoated metal layer is responsible for the conduction of charge carriers. We found that the metal oxide layer coupled between pentacene and metal layers played an important role in improving the field-effect transistor characteristics of OTFTs. Devices with the bilayer S-D electrodes showed enhanced hole-injection compared to those with only metal electrode. High field-effect mobility of 0.4cm2∕Vs and on/off current ratios of 104 were obtained in the pentacene based TFTs using the bilayer S-D electrodes at a gate bias of −40V. The improvement is attributed to the reduction in the contact barrier and the prevention of metal diffusion into the organic layer and/or unfavorable chemical reaction between the organic layer and the metal electrode.
Measurement of Zn0.95Cd0.05O∕ZnO (0001) heterojunction band offsets by x-ray photoelectron spectroscopy
Authors: Chen Jau-Jiun , Ren F. , Li Yuanjie , Norton D. P. , Pearton S. J. , Osinsky A. , Dong J. W. , Chow P. P. , Weaver J. F.
Published: November 2005

X-ray photoelectron spectroscopy was used to measure the energy discontinuity in the valence band (ΔEv) of Zn0.95Cd0.05O∕ZnO heterostructures grown by rf plasma-enhanced molecular-beam epitaxy. A value of ΔEv=0.17±0.03eV was obtained by using the Zn 2p energy level as a reference. Given the experimental band gap of 2.9 eV for the Zn0.95Cd0.05O, this would indicate a conduction band offset ΔEC of 0.30 eV in this system.
Up conversion from visible to ultraviolet in bulk ZnO implanted with Tm ions
Authors: Monteiro T. , Neves A. J. , Soares M. J. , Carmo M. C. , Peres M. , Alves E. , Rita E.
Published: November 2005

We report on the up-converted ultraviolet near-band edge emission of bulk ZnO generated by visible and ultraviolet photons with energies below the band gap. This up-converted photoluminescence was observed in samples intentionally doped with Tm ions, suggesting that the energy levels introduced by the rare earth ion in the ZnO band gap are responsible for this process.
Microscopic observations of condensation of water on lotus leaves
Authors: Cheng Yang-Tse , Rodak Daniel E. , Angelopoulos Anastasios , Gacek Ted
Published: November 2005

We report an in situ observation of water condensation and evaporation on lotus leaf surfaces inside an environmental scanning electron microscope. The real-time observation shows, at the micrometer length scale, how water drops grow to large contact angles during water condensation, and decrease in size and contact angle during the evaporation phase of the experiment. To rationalize the observations, we propose a geometric model for liquid drops on rough surfaces when the size of the drop and surface roughness scale are comparable. This model suggests that when drop size and surface roughness are of the same magnitude, such as micrometer size water drops on lotus leaves, well-known equations for wetting on rough surfaces may not be applicable.
Determination of preferred habitats of early benthic juvenile California spiny lobster, Panulirus interruptus, on the Pacific coast of Baja California Sur, Mexico
Authors: Castañeda-Fernández de Lara Verónica , Butler Mark , Hernández-Vázquez Sergio , Guzmán del Próo Sergio , Serviere-Zaragoza Elisa
Published: November 2005

The habitat requirements of early benthic stage juveniles of California spiny lobster Panulirus interruptus are known only from studies conducted near its northernmost geographic range, where environmental conditions differ markedly from those along the Pacific coast of the southern Baja California Peninsula (Mexico). We determined the natural habitat of this stage of P. interruptus in the central portion of their range from sampling the available dominant vegetated habitats included various seagrasses and macroalgae. Additionally, experiments on habitat selection by early benthic juvenile P. interruptus were performed under laboratory conditions to test natural substrate selection and whether selection of substrata is affected by odour signals. Despite the abundance of different macrophytes as habitat, 93% of the juvenile lobsters were found at the base of the blades of Phyllospadix spp. in the intertidal zone at 0 to 3 m. The highest juvenile densities were found in September at both sites. In laboratory experiments, juvenile lobsters preferred, in order of preference, Gelidium robustum, Phyllospadix, Plocamium pacificum, and holdfasts of the kelp Macrocystis pyrifera. A second laboratory experiment showed that these preferences were affected by odour signals. Results indicate that the ecology of juvenile P. interruptus off the coast of the Mexican Baja is similar to that observed off the coast of southern California.
Glucocorticoids and serotonin alter glucocorticoid receptor mRNA levels in fetal guinea-pig hippocampal neurons, in vitro
Authors: Erdeljan P. , Andrews M. H. , MacDonald J. F. , Matthews S. G.
Published: November 2005

The hypothalamic–pituitary–adrenal (HPA) axis is susceptible to programming during fetal life. Such programming occurs, at least partially, at the level of the hippocampus. The hippocampus plays a central role in regulation of the HPA axis and release of endogenous glucocorticoids, via mediation of glucocorticoid negative feedback. Fetal exposure to synthetic glucocorticoids can permanently alter glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) levels within the hippocampus, and serotonin is thought to be involved in this process. In the present study, we hypothesised that dexamethasone, cortisol and serotonin exposure would modify GR mRNA expression within fetal guinea-pig hippocampal cultures. Cultures were derived from 40-day-old guinea-pig fetuses, and were exposed to 0, 1, 10 and 100 nm dexamethasone, cortisol or serotonin for 4 days. Expression of GR and MR mRNA was examined by in situ hybridisation followed by high-resolution silver emulsion autoradiography. Four-day exposure to dexamethasone (P < 0.05; 100 nm) or cortisol (P = 0.08; 100 nm) downregulated the expression of GR mRNA within neurons. There was no change in the expression of MR mRNA levels following cortisol treatment. Exposure to serotonin (100 nm) significantly increased GR mRNA levels in hippocampal neurons. We conclude that synthetic and endogenous glucocorticoids, as well as serotonin, can influence GR expression during hippocampal development and in this way may act to permanently programme HPA function.
Unconscious processing of orientation and color without primary visual cortex
Authors: Boyer Jennifer L. , Harrison Stephenie , Ro Tony
Published: November 2005

In humans, the primary visual cortex (V1) is essential for conscious vision. However, even without V1 and in the absence of awareness, some preserved ability to accurately respond to visual inputs has been demonstrated, a phenomenon referred to as blindsight. We used transcranial magnetic stimulation (TMS) to deactivate V1, producing transient blindness for visual targets presented in a foveal, TMS-induced scotoma. Despite unawareness of these targets, performance on forced choice discrimination tasks for orientation (experiment 1) and color (experiment 2) were both significantly above chance. In addition to demonstrating that TMS can be successfully used to induce blindsight within a normal population, these results suggest a functioning geniculoextrastriate visual pathway that bypasses V1 and can process orientation and color in the absence of conscious awareness.
The amyloid stretch hypothesis: Recruiting proteins toward the dark side
Authors: Esteras-Chopo Alexandra , Serrano Luis , de la Paz Manuela López
Published: November 2005

A detailed understanding of the molecular events underlying the conversion and self-association of normally soluble proteins into amyloid fibrils is fundamental to the identification of therapeutic strategies to prevent or cure amyloid-related disorders. Recent investigations indicate that amyloid fibril formation is not just a general property of the polypeptide backbone depending on external factors, but that it is strongly modulated by amino acid side chains. Here, we propose and address the validation of the premise that the amyloidogenicity of a protein is indeed localized in short protein stretches (amyloid stretch hypothesis). We demonstrate that the conversion of a soluble nonamyloidogenic protein into an amyloidogenic prone molecule can be triggered by a nondestabilizing six-residue amyloidogenic insertion in a particular structural environment. Interestingly enough, although the inserted amyloid sequences clearly cause the process, the protease-resistant core of the fiber also includes short adjacent sequences from the otherwise soluble globular domain. Thus, short amyloid stretches accessible for intermolecular interactions trigger the self-assembly reaction and pull the rest of the protein into the fibrillar aggregate. The reliable identification of such amyloidogenic stretches in proteins opens the possibility of using them as targets for the inhibition of the amyloid fibril formation process.
Quantitative NMR spectroscopy of supramolecular complexes: Dynamic side pores in ClpP are important for product release
Authors: Sprangers Remco , Gribun Anna , Hwang Peter M. , Houry Walid A. , Kay Lewis E.
Published: November 2005

The highly conserved, 300-kDa cylindrical protease ClpP is an important component of the cellular protein quality machinery. It consists of 14 subunits arranged into two heptameric rings that enclose a large chamber containing the protease active sites. ClpP associates with ClpX and ClpA ATPases that unfold and translocate substrates into the protease catalytic chamber through axial pores located at both ends of the ClpP cylinder. Although the pathway of substrate delivery is well established, the pathway of product release is unknown. Here, we use recently developed transverse relaxation optimized spectroscopy (TROSY) of methyl groups to show that the interface between the heptameric rings exchanges between two structurally distinct conformations. The conformational exchange process has been quantified by magnetization exchange and methyl TROSY relaxation dispersion experiments recorded between 0.5°C and 40°C, so that the thermodynamic properties for the transition could be obtained. Restriction of the observed motional freedom in ClpP through the introduction of a cysteine linkage results in a protease where substrate release becomes significantly slowed relative to the rate observed in the reduced enzyme, suggesting that the observed motions lead to the formation of transient side pores that may play an important role in product release.
Glutathionylation of chloroplast thioredoxin f is a redox signaling mechanism in plants
Authors: Michelet Laure , Zaffagnini Mirko , Marchand Christophe , Collin Valérie , Decottignies Paulette , Tsan Pascale , Lancelin Jean-Marc , Trost Paolo , Miginiac-Maslow Myroslawa , Noctor Graham , Lemaire Stéphane D.
Published: November 2005

Thioredoxin f (TRXf) is a key factor in the redox regulation of chloroplastic carbon fixation enzymes, whereas glutathione is an important thiol buffer whose status is modulated by stress conditions. Here, we report specific glutathionylation of TRXf. A conserved cysteine is present in the TRXf primary sequence, in addition to its two active-site cysteines. The additional cysteine becomes glutathionylated when TRXf is exposed to oxidized glutathione or to reduced glutathione plus oxidants. No other chloroplastic TRX, from either
Arabidopsis
or
Chlamydomonas
, is glutathionylated under these conditions. Glutathionylation decreases the ability of TRXf to be reduced by ferredoxin-thioredoxin reductase and results in impaired light activation of target enzymes in a reconstituted thylakoid system. Although several mammalian proteins undergoing glutathionylation have already been identified, TRXf is among the first plant proteins found to undergo this posttranslational modification. This report suggests that a crosstalk between the TRX and glutathione systems mediates a previously uncharacterized form of redox signaling in plants in stress conditions.
Development of spectral and temporal response selectivity in the auditory cortex
Authors: Chang Edward F. , Bao Shaowen , Imaizumi Kazuo , Schreiner Christoph E. , Merzenich Michael M.
Published: November 2005

The mechanisms by which hearing selectivity is elaborated and refined in early development are very incompletely determined. In this study, we documented contributions of progressively maturing inhibitory influences on the refinement of spectral and temporal response properties in the primary auditory cortex. Inhibitory receptive fields (IRFs) of infant rat auditory cortical neurons were spectrally far broader and had extended over far longer duration than did those of adults. The selective refinement of IRFs was delayed relative to that of excitatory receptive fields by an ≈2-week period that corresponded to the critical period for plasticity. Local application of a GABA
A
receptor antagonist revealed that intracortical inhibition contributes to this progressive receptive field maturation for response selectivity in frequency. Conversely, it had no effect on the duration of IRFs or successive-signal cortical response recovery times. The importance of exposure to patterned acoustic inputs was suggested when both spectral and temporal IRF maturation were disrupted in rat pups reared in continuous, moderate-intensity noise. They were subsequently renormalized when animals were returned to standard housing conditions as adults.