bluuebunny/crossref_metadata_2025 huggingface dataset:
SCIENCE IN ADAB LITERATURE
Authors: Lettinck Paul
Published: February 2011

Books belonging to adab literature present material about a variety of subjects, considered from various points of view, such as religious, scientific, historical, literary, etc. They contain knowledge and at the same time entertainment for educated people. Here we consider the content of two adab works, insofar as they discuss subjects from the scientific point of view: (an extract of) Faṣl al-Khiṭāb by al-Tīfāshī (d. 1253) and Mabāhij al-fikar wa-manāhij al-ʿibar by al-Waṭwāṭ (d. 1318).

Al-Tīfāshī's work discusses astronomical and meteorological subjects. The passages on astronomy give the usual Aristotelian cosmological picture of the world in a simplified version for non-specialists. The passages on meteorological subjects explain these phenomena in agreement with Aristotle's theory of the double exhalation, and it appears that they are based to a large extent on Ibn Sīnā's interpretation of this theory.

The book of al-Waṭwāṭ consists of four sections, which deal with the heaven, the earth, animals and plants respectively. One chapter of the first section deals with meteorological phenomena and presents a survey of the explanations current in his time, such as may be found in the works of al-Kindī and Ibn Sīnā.

One will probably not find new and original scientific ideas in the adab literature, but one gets an impression of how besides knowledge of Qurʾān, ḥadīth, poetry and literary prose scientific knowledge was a part of the education of a certain class of people, also of those whose special interest was not science. It also appears that the subjects of science were not restricted to those which were useful for religion and Muslim society. Science was an integrated activity in society, pursued for intellectual satisfaction and pleasure in knowledge, and most groups in that society held that there was nothing in it that would be incompatible with Islam as a religion. This would support the ‘appropriation thesis’ defended by Sabra, that science in medieval Islamic society was well assimilated and widely accepted, as opposed to the the ‘marginality thesis’ adopted by von Grünebaum, that science was a marginal activity, restricted to small elite circles and not rooted in society.
A première vue, marqueur d'aspectde dicto
Authors: LENEPVEU VERONIQUE
Published: February 2011

RESUME

On se propose d'étudier le fonctionnement sémantico-pragmatique de la locution adverbialeà première vuequand elle introduit un point de vue au sens de Nølke (1994) et qu'elle joue un rôle de « cadratif » prospectif (Charolles 1997). Dans cette perspective, nous nous intéressons aux enchaînements discursifs plus ou moins stéréotypés dans lesquels s'inscrit la locution. En particulier, nous établissons une relation entreà première vueet des expressions qui signalent une évolution dans le temps du jugement du locuteur (à y regarder de plus près, en y réfléchissant, tout bien réfléchi, tout compte fait, tout bien considéré, . . .).
Dividend policy in Norwegian banking before 1914
Authors: Øksendal Lars Fredrik
Published: February 2011

This article discusses the dividend strategy adopted by Norwegian commercial banks before 1914. Based on a unique data set covering all banks in the period 1882– 1913 as well as six other institutions for the pre-1882 period, I identify the existence of a strong bias towards the payment of high and stable dividends to shareholders. The origins of such bias lie in the specific institutional set-up of commercial banking, the expectations of shareholders and the absence of developed securities markets. Combined with a strong preference for high gearing, this feature contributed to increase the fragility of the Norwegian banking system.
ALTERNATING EULER SUMS AND SPECIAL VALUES OF THE WITTEN MULTIPLE ZETA FUNCTION ATTACHED TO
Authors: ZHAO JIANQIANG
Published: February 2011

We study the Witten multiple zeta function associated with the Lie algebra$\so $. Our main result shows that its special values at nonnegative integers are always expressible by alternating Euler sums. More precisely, every such special value of weightwat least 2 is a finite ℚ-linear combination of alternating Euler sums of weightwand depth at most 2, except when the only nonzero argument is one of the two last variables, in which caseζ(w−1) is needed.
International practices
Authors: Adler Emanuel , Pouliot Vincent
Published: February 2011

In this article, we approach world politics through the lens of its manifold practices, which we define as competent performances. Studying International Relations (IR) from the perspective of international practices promises three key advances. First, by focusing on practices in IR, we can understand both IR theory and international politics better or differently. World politics can be conceived as structured by practices, which give meaning to international action, make possible strategic interaction, and are reproduced, changed, and reinforced by international action and interaction. This focus helps broaden the ontology of world politics, serves as a focal point around which debates in IR theory can be structured, and can be used as a unit of analysis that transcends traditional understandings of ‘levels of analysis’. We illustrate what an international practice is by revisiting Thomas Schelling's seminal works on bargaining. Second, with the help of illustrations of deterrence and arms control during the Cold War and of post-Cold War practices such as cooperative security, we show how practices constitute strategic interaction and bargaining more generally. Finally, a practice perspective opens an exciting and innovative research agenda, which suggests new research questions and puzzles, and revisits central concepts of our discipline, including power, history, and strategy.
Cosmopolitanism, climate change, and greenhouse emissions trading
Authors: Page Edward A.
Published: February 2011

This article examines the question of whether international markets in allowances conferring the right to emit greenhouse gases are consistent with a cosmopolitan approach to global and intergenerational justice. After placing emissions trading within the context of both climate change policy and cosmopolitan political theory, three normative objections are examined to the use of emissions trading to mitigate the threat of dangerous climate change. Each objection arises from a different application of cosmopolitan thinking: (i) the potentially corrosive impact of greater use of emissions allowances markets on the environmental values of successive generations of atmospheric users; (ii) the awkward relationship between emissions markets and the norms of procedural justice endorsed by all prominent cosmopolitans; and (iii) the injustice expressed by policy instruments that commodify the atmosphere. It is argued that, while each objection should prompt some care in the construction and implementation of emissions trading schemes to guarantee their legitimacy among existing and future users of the atmosphere, they do not generate a decisive normative challenge to the use of markets, properly defined and regulated, to slow global warming.
Induced polarization signatures of cations exhibiting differential sorption behaviors in saturated sands
Authors: Vaudelet P. , Revil A. , Schmutz M. , Franceschi M. , Bégassat P.
Published: February 2011

Two sets of experiments were designed to understand the change in induced polarization associated with the sorption of copper and sodium, exhibiting distinct sorption behavior on a silica sand. A sand column experiment was first performed to see the change in the complex conductivity during the advective transport of a copper sulfate solution. A second set of experiments was done with the sand at equilibrium with various solutions of NaCl and CuSO4. In the first experiment, the copper sulfate solution replaced a sodium chloride solution, keeping the electrical conductivity of the solution nearly constant. During the passage of the copper sulfate solution, the apparent phase angle decreased from 3 ± 0.2 to 0.5 ± 0.2 mrad, while the magnitude of the conductivity of the sand remained nearly constant. A quantitative model is proposed to explain the change in the complex conductivity as a function of the chemistry assuming a polarization mechanism associated with the Stern layer (the inner part of the electrical double layer coating the water‐mineral interface). The Stern layer polarization is combined with a complexation model describing the competitive sorption of copper and sodium at the pore water interface. The change of the phase lag is directly associated with the ion exchange between sodium and copper at the surface of the silica grains. The explanation of the observed phase differences between Na and Cu relies on their different complexation behaviors, with Na being loosely absorbed, while Cu forms relatively strong complexation with both inner (monodentate) and outer sphere (bidentate) complexes. The replacement of Cu2+ by Na+ is less favorable; therefore, the kinetics of such a replacement is much slower than for the opposite replacement (Na+ by Cu2+). We were able to reproduce the changes in the phase lags at thermodynamic equilibrium near the relaxation frequency and in the frequency domain. These measurements and modeling results open the door to the quantitative interpretation of spectral induced polarization data in the field in terms of quantification of the sorption processes.
A model for the topology of active ribosomal RNA genes
Authors: Denissov Serguei , Lessard Frédéric , Mayer Christine , Stefanovsky Victor , van Driel Marc , Grummt Ingrid , Moss Tom , Stunnenberg Hendrik G
Published: February 2011

The Christmas tree view of active ribosomal RNA (rRNA) genes suggests a gene topology in which a large number of nascent rRNA transcripts are prevented from intertwining. The way in which this is achieved has remained unclear. By using a combination of chromatin immunoprecipitation and chromosome conformation capture techniques, we show that the promoter, upstream region and terminator R3 of active rRNA genes are held together spatially throughout the cell cycle, forming a stable core around which the transcribed region is organized. We suggest a new core–helix model for the topology of rRNA genes, that provides a structural basis for the productive synthesis or rRNA.
Histone deacetylase inhibitor activity in royal jelly might facilitate caste switching in bees
Authors: Spannhoff Astrid , Kim Yong Kee , Raynal Noel J ‐M , Gharibyan Vazganush , Su Ming‐Bo , Zhou Yue‐Yang , Li Jia , Castellano Sabrina , Sbardella Gianluca , Issa Jean‐Pierre J , Bedford Mark T
Published: February 2011

Worker and queen bees are genetically indistinguishable. However, queen bees are fertile, larger and have a longer lifespan than their female worker counterparts. Differential feeding of larvae with royal jelly controls this caste switching. There is emerging evidence that the queen‐bee phenotype is driven by epigenetic mechanisms. In this study, we show that royal jelly—the secretion produced by the hypopharyngeal and mandibular glands of worker bees—has histone deacetylase inhibitor (HDACi) activity. A fatty acid, (E)‐10‐hydroxy‐2‐decenoic acid (10HDA), which accounts for up to 5% of royal jelly, harbours this HDACi activity. Furthermore, 10HDA can reactivate the expression of epigenetically silenced genes in mammalian cells. Thus, the epigenetic regulation of queen‐bee development is probably driven, in part, by HDACi activity in royal jelly.
Respiratory fluid mechanics
Authors: Grotberg James B.
Published: February 2011

This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from “capillary-elastic instabilities,” as well as nonlinear stabilization from oscillatory core flow which we call the “oscillating butter knife;” liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg–Borgas–Gaver shock.
Dynamic nuclear polarization assisted spin diffusion for the solid effect case
Authors: Hovav Yonatan , Feintuch Akiva , Vega Shimon
Published: February 2011

The dynamic nuclear polarization (DNP) process in solids depends on the magnitudes of hyperfine interactions between unpaired electrons and their neighboring (core) nuclei, and on the dipole–dipole interactions between all nuclei in the sample. The polarization enhancement of the bulk nuclei has been typically described in terms of a hyperfine-assisted polarization of a core nucleus by microwave irradiation followed by a dipolar-assisted spin diffusion process in the core–bulk nuclear system. This work presents a theoretical approach for the study of this combined process using a density matrix formalism. In particular, solid effect DNP on a single electron coupled to a nuclear spin system is considered, taking into account the interactions between the spins as well as the main relaxation mechanisms introduced via the electron, nuclear, and cross-relaxation rates. The basic principles of the DNP-assisted spin diffusion mechanism, polarizing the bulk nuclei, are presented, and it is shown that the polarization of the core nuclei and the spin diffusion process should not be treated separately. To emphasize this observation the coherent mechanism driving the pure spin diffusion process is also discussed. In order to demonstrate the effects of the interactions and relaxation mechanisms on the enhancement of the nuclear polarization, model systems of up to ten spins are considered and polarization buildup curves are simulated. A linear chain of spins consisting of a single electron coupled to a core nucleus, which in turn is dipolar coupled to a chain of bulk nuclei, is considered. The interaction and relaxation parameters of this model system were chosen in a way to enable a critical analysis of the polarization enhancement of all nuclei, and are not far from the values of 13C nuclei in frozen (glassy) organic solutions containing radicals, typically used in DNP at high fields. Results from the simulations are shown, demonstrating the complex dependences of the DNP-assisted spin diffusion process on variations of the relevant parameters. In particular, the effect of the spin lattice relaxation times on the polarization buildup times and the resulting end polarization are discussed, and the quenching of the polarizations by the hyperfine interaction is demonstrated.
Note: The intermodulation lockin analyzer
Authors: Tholén Erik A. , Platz Daniel , Forchheimer Daniel , Schuler Vivien , Tholén Mats O. , Hutter Carsten , Haviland David B.
Published: February 2011

Nonlinear systems can be probed by driving them with two or more pure tones while measuring the intermodulation products of the drive tones in the response. We describe a digital lockin analyzer which is designed explicitly for this purpose. The analyzer is implemented on a field-programmable gate array, providing speed in analysis, real-time feedback, and stability in operation. The use of the analyzer is demonstrated for intermodulation atomic force microscopy. A generalization of the intermodulation spectral technique to arbitrary drive waveforms is discussed.
Characterization of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][Tf2N])/TX-100/cyclohexane ternary microemulsion: Investigation of photoinduced electron transfer in this RTIL containing microemulsion
Authors: Sarkar Souravi , Pramanik Rajib , Ghatak Chiranjib , Rao Vishal Govind , Sarkar Nilmoni
Published: February 2011

In this study we have characterized a ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethyl- sulfonyl)imide containing ternary nonaqueous microemulsion ([Emim][Tf2N]//TX-100/cyclo- hexane). The phase behavior and dynamic light scattering study show that the [Emim][Tf2N]/TX-100/cyclohexane three component system can form microemulsion with [Emim][Tf2N] as polar core at suitable condition. We have investigated photoinduced electron transfer (PET) using dimethyl aniline as electron donor and several Coumarin dyes as electron acceptor molecules at two different R values (R = [ionic liquid]/[surfactant]) to observe how the dynamics of the PET rate is affected in this type of confined microenvironment compared to that of the PET dynamics in neat ionic liquid and other pure solvent media. The plot of observed kq values with the free energy change (ΔG0) for electron transfer reaction shows an apparent inversion in the observed rate as predicted by the Marcus theory.
Molecular dynamics study of the melting curve of NiTi alloy under pressure
Authors: Zeng Zhao-Yi , Hu Cui-E , Cai Ling-Cang , Chen Xiang-Rong , Jing Fu-Qian
Published: February 2011

The melting curve of NiTi alloy was predicted by using molecular dynamics simulations combining with the embedded atom model potential. The calculated thermal equation of state consists well with our previous results obtained from quasiharmonic Debye approximation. Fitting the well-known Simon form to our Tm data yields the melting curves for NiTi: 1850(1 + P/21.938)0.328 (for one-phase method) and 1575(1 + P/7.476)0.305 (for two-phase method). The two-phase simulations can effectively eliminate the superheating in one-phase simulations. At 1 bar, the melting temperature of NiTi is 1575 ± 25 K and the corresponding melting slope is 64 K/GPa.
Luminescence degradation in phosphorescent organic light-emitting devices by hole space charges
Authors: Zamani Siboni, Hossein , Luo Yichun , Aziz Hany
Published: February 2011

We studied electroluminescence degradation in phosphorescent organic light-emitting devices (PHOLEDs) and found that two distinctive mechanisms are responsible for device degradation depending on the device structure. For a device without a hole blocking layer (HBL), excess holes penetrate into the electron transport layer (ETL) and lead to the deterioration of the ETL adjacent to the interface of the emitting layer. The lower electron transport capacity of the degraded ETL alters the balance in hole/electron injection into the emitting layer and results in a decrease in the luminescence efficiency of the PHOLEDs. For a device with a HBL, on the other hand, holes accumulate and become trapped in the emitting layer, and result in a decrease in the luminescence efficiency of the PHOLEDs, likely due to their role in acting as exciton quenchers or as nonradiative charge recombination centers.
Low temperature ultrahigh vacuum noncontact atomic force microscope in the pendulum geometry
Authors: Gysin U. , Rast S. , Kisiel M. , Werle C. , Meyer E.
Published: February 2011

A noncontact atomic force microscope (nc-AFM) operating in magnetic fields up to ±7 T and liquid helium temperatures is presented in this article. In many common AFM experiments the cantilever is mounted parallel to the sample surface, while in our system the cantilever is assembled perpendicular to it; the so called pendulum mode of AFM operation. In this mode measurements employing very soft and, therefore, ultrasensitive cantilevers can be performed. The ultrahigh vacuum conditions allow to prepare and transfer cantilevers and samples in a requested manner avoiding surface contamination. We demonstrate the possibility of nc-AFM and Kelvin force probe microscopy imaging in the pendulum mode. Ultrasensitive experiments on small spin ensembles are presented as well.
The transition from two-stage to three-stage evolution of wetting layer of InAs/GaAs quantum dots caused by postgrowth annealing
Authors: Zhou G. Y. , Chen Y. H. , Yu J. L. , Zhou X. L. , Ye X. L. , Jin P. , Wang Z. G.
Published: February 2011

For the InAs/GaAs quantum dot (QD) system, the evolution of wetting layer (WL) with InAs deposition thickness has been studied under different postgrowth annealing (PGA) durations using reflectance difference spectroscopy. For the sample without PGA, WL thickness remains constant after the formation of QDs, exhibiting a typical two-stage evolution, whereas for the samples with PGA, WL thickness continuously increases linearly with a reduced slope after the formation of QDs and is fixed in ripening growth, indicating a three-stage evolution. By adopting a theoretical model, we have well simulated the two kinds of evolution and found that the variations of QD’s morphology and the interaction of QDs occurring during PGA lead to the different evolution behaviors of WL.
Attributing sense to some integrals in Regge calculus
Authors: Khatsymovsky V. M.
Published: February 2011

Regge calculus minisuperspace action in the connection representation has the form in which each term is linear over some field variable (scale of area-type variable with sign). We are interested in the result of performing integration over connections in the path integral (now usual multiple integral) as function of area tensors. We study analytical properties of this function in the extended (as compared to physical one) region when its arguments (area tensors) are allowed to be independent of each other. To find this function (or distribution), we compute its moments, i.e., integrals with monomials over area tensors. Then the function of interest should be recovered from the moments. Calculation proceeds through intermediate appearance of δ-functions and integrating them out. Up to a singular part with support on some discrete set of physically unattainable points, the function of interest has finite moments. This function in physical region should therefore exponentially decay at large areas and it really does being restored from moments. This gives for gravity a way of defining such nonabsolutely convergent integral as path integral.
The extent of molecular orientation at liquid/vapor interface of pyridine and its alkyl derivatives by molecular dynamics simulation
Authors: Ghatee Mohammad Hadi , Zolghadr Amin Reza , Moosavi Fatemeh , Pakdel Leila
Published: February 2011

In this paper, molecular dynamics simulation was performed to investigate the liquid/vapor interfacial structure of neat polar liquids. Large-scale ensembles of liquid pyridine and its alkyl derivatives, 4-methylpyridine and 4-ethylpyridine, were simulated by classical molecular dynamics at 298 K. For the liquid system of low polarity, the surface density profile of the atoms meet exactly at the middle of interfacial region, and atoms of hydrophobic nature can be hardly discriminated from hydrophilic ones in either vapor or liquid sides. For a liquid system of high polarity, the density profile of atoms with different nature is highly discriminated all over the interfacial region, and as the polarity increases, a dense region of atomic density is clearly developed in the subsurface region. The recognized bivariate method was also used to study the molecular orientational distribution quantitatively. Orientational analysis of the three liquid systems indicates that the pyridine ring plane in the outmost surface tends to be vertical. Its tendency in the innermost interfacial region is parallel. The orientational states available to 4-ethylpyridine and pyridine are discriminated by predicting the possibility of a bisector-wise tumbling for the ring plane in pyridine and a side-wise tumbling in 4-ethylpyridine. The orientational distribution maps explain the trend of experimental surface tension and surface entropy. As the dipole moment of these liquids increases with the alkyl chain length, the surface structural profile changes from a regular definite one to a surface of complex atomic structure involving a dense phase near the interface. The development of dense region in alkyl derivatives is the result of segregation of molecules due to the alkyl group, which is captured and discriminated by molecular dynamics simulation even when the length of a short alkyl chain is increased by one carbon atom.
Beyond the Yablonovitch limit: Trapping light by frequency shift
Authors: Markvart Tom
Published: February 2011

It is shown that randomizing the photon distribution over the frequency as well as orientation variables dramatically improves the efficiency of optical confinement in a weakly absorbing material such as crystalline silicon. The enhancement in average optical path length over the Yablonovitch limit [E. Yablonovitch, J. Opt. Soc. Am. 72, 899 (1982)] is given by an inverse Boltzmann factor of the frequency shift, making it possible to manufacture, for example, efficient crystalline silicon solar cells of thickness barely 1 μm.
Dynamic magnetic island coalescence and associated electron acceleration
Authors: Tanaka Kentaro G. , Fujimoto Masaki , Badman Sarah V. , Shinohara Iku
Published: February 2011

The system size dependence of electron acceleration during large-scale magnetic island coalescence is studied via a two-dimensional particle-in-cell simulation. Using a simulation box that is larger than those used in previous studies, injection by merging line acceleration and subsequent reacceleration inside a merged island are found to be the mechanisms for producing the most energetic electrons. This finding and knowledge of the reacceleration process enable us to predict that the high energy end of the electron energy spectrum continues to expand as the merged island size increases. Both the merging line acceleration and the reacceleration within a merged island require the island coalescence process to be so dynamic as to involve fast in-flow toward the center of a merged island. Once this condition is met in an early stage of the coalescence, it is likely to stay in the subsequent phase. In other words, if the thin elongated current sheet is initially able to host the dynamic magnetic island coalescence process, it will be a site where repeated upgrades in the maximum energy of electrons occur in a systematic manner.
Experimental verification of reduced intersubband scattering in ordered nanopore lattices
Authors: Dias N. L. , Garg A. , Reddy U. , Young J. D. , Bassett K. P. , Li X. , Coleman J. J.
Published: February 2011

A photoluminescence study of emission from a periodically perforated quantum well at 77 K is presented. Good agreement is observed between numerical predictions and experimental results. The effects of pore diameter on peak emission wavelength and relative emission from second excited subbands are analyzed. The results are found to be consistent with predictions of reduced intersubband scattering rate in nanopore lattices due to the reduced wave function overlap between the initial and final states arising from the in-plane periodicity.
Insights on the impact of a plane drop on a thin liquid film
Authors: Coppola Gennaro , Rocco Giuseppe , de Luca Luigi
Published: February 2011

Numerical simulations of early and intermediate instants of a plane two-dimensional drop impact on a preexisting thin film of the same liquid are performed. The evolution of the phenomenon is analyzed by solving the free-surface Navier–Stokes equations by means of a volume of fluid (VOF) method. Viscous, inertial and surface tension forces are taken into account; gravity is neglected. The so-called splashing regime is emphasized, where the emergence of an initial horizontal ejecta sheet is followed by the formation of an almost vertical lamella sheet, which is the planar counterpart of the well known splashing-crown of spherical geometry. Overall velocity and pressure fields as well as detailed interface shapes are presented, and several insights on the relevant scaling laws are furnished. In the ejecta sheet (jet) regime a major result is the finding of a deviation from the standard square root behavior for the dependence on time of the contact length of sheet first emergence, which is proved to be crucial in the subsequent original application of the potential theory of Howison et al. [J. Fluid Mech. 542, 1 (2005)]. In the lamella sheet regime, the outwards expansion of its base is discussed in connection with the theory of the formation of a kinematic discontinuity within the underneath film of Yarin and Weiss [J. Fluid Mech. 283, 141 (1995)]. Analogies between planar and axysymmetric configurations are discussed.
The electromagnetic property of chemically reduced graphene oxide and its application as microwave absorbing material
Authors: Wang Chao , Han Xijiang , Xu Ping , Zhang Xiaolin , Du Yunchen , Hu Surong , Wang Jingyu , Wang Xiaohong
Published: February 2011

The residual defects and groups in chemically reduced graphene oxide cannot only improve the impedance match characteristic and prompt energy transition from contiguous states to Fermi level, but also introduce defect polarization relaxation and groups’ electronic dipole relaxation, which are all in favor of electromagnetic wave penetration and absorption. The chemically reduced graphene oxide shows enhanced microwave absorption compared with graphite and carbon nanotubes, and can be expected to display better absorption than high quality graphene, exhibiting a promising prospect as microwave absorbing material.
Graphitized carbon on GaAs(100) substrates
Authors: Simon J. , Simmonds P. J. , Woodall J. M. , Lee M. L.
Published: February 2011

We report on the formation of graphitized carbon on GaAs(100) surfaces by molecular beam epitaxy. We grew highly carbon-doped GaAs on AlAs, which was then thermally etched in situ leaving behind carbon atoms on the surface. After thermal etching, Raman spectra revealed characteristic phonon modes for sp2-bonded carbon, consistent with the formation of graphitic crystallites. We estimate that the graphitic crystallites are 1.5–3 nm in size and demonstrate that crystallite domain size can be increased through the use of higher etch temperatures.
Position of defects with respect to domain walls in Fe3+-doped Pb[Zr0.52Ti0.48]O3 piezoelectric ceramics
Authors: Jakes Peter , Erdem Emre , Eichel Rüdiger-A. , Jin Li , Damjanovic Dragan
Published: February 2011

The position of (FeZr,Ti′−VO••)• defect complexes in Pb[Zr0.52Ti0.48]O3 (PZT) piezoelectric ceramics was investigated by means of electron paramagnetic resonance (EPR) spectroscopy. The method of analysis pursued to obtain information on the (FeZr,Ti′−VO••)• position is to compare the EPR spectra of Fe3+-doped PZT specimen at different states, i.e., a powder that is representative for a system with considerably reduced amount of non-180° domain walls and a sintered ceramic of identical composition but with markedly developed domain structure. By considering the local site symmetry for the Fe3+-functional center, indirect evidence is obtained that the (FeZr,Ti′−VO••)• defect complexes are located within domains and not at domain walls.
Phase diagrams of colloidal spheres with a constant zeta-potential
Authors: Smallenburg Frank , Boon Niels , Kater Maarten , Dijkstra Marjolein , van Roij René
Published: February 2011

We study suspensions of colloidal spheres with a constant zeta-potential within Poisson–Boltzmann theory, quantifying the discharging of the spheres with increasing colloid density and decreasing salt concentration. We use the calculated renormalized charge of the colloids to determine their pairwise effective screened-Coulomb repulsions. Bulk phase diagrams in the colloid concentration–salt concentration representation follow, for various zeta-potentials, by a mapping onto published fits of phase boundaries of point-Yukawa systems. Although the resulting phase diagrams do feature face-centered cubic and body-centered cubic phases, they are dominated by the (re-entrant) fluid phase due to the colloidal discharging with increasing colloid concentration and decreasing salt concentration.
Conduction-type control of fullerene films from n- to p-type by molybdenum oxide doping
Authors: Kubo Masayuki , Iketaki Kai , Kaji Toshihiko , Hiramoto Masahiro
Published: February 2011

Conduction-type control of fullerene (C60) films from n- to p-type by doping with molybdenum oxide (MoO3) was demonstrated. The energetic value of the Fermi level, 4.60 eV, for nondoped C60 films measured by the Kelvin vibrating capacitor method was positively shifted to 5.88 eV, and approached the valence band by the coevaporated doping of MoO3 at a concentration of 3300 ppm. The existence of upward band bending of the Schottky junction formed at the interface between a metal and a p-type C60 film formed by MoO3 doping was confirmed based on its photovoltaic properties.
Turn-key module for neutron scattering with sub-micro-eV resolution
Authors: Georgii R. , Brandl G. , Arend N. , Häußler W. , Tischendorf A. , Pfleiderer C. , Böni P. , Lal J.
Published: February 2011

We report the development of a compact turn-key module that boosts the resolution in quasielastic neutron scattering by several orders of magnitude down to the low sub-micro-eV range. It is based on a pair of neutron resonance spin flippers that generate a well defined temporal intensity modulation, also known as Modulation of IntEnsity by Zero Effort (MIEZE). The module may be used under versatile conditions, in particular, in applied magnetic fields and for depolarizing and incoherently scattering samples. We demonstrate the power of MIEZE in studies of the helimagnetic order in MnSi under applied magnetic fields.
Effect of resistance-area product on spin-transfer switching in MgO-based magnetic tunnel junction memory cells
Authors: Zeng Z. M. , Khalili Amiri P. , Rowlands G. , Zhao H. , Krivorotov I. N. , Wang J.-P. , Katine J. A. , Langer J. , Galatsis K. , Wang K. L. , Jiang H. W.
Published: February 2011

We use ultrafast current-induced switching measurements to study spin-transfer switching performance metrics, such as write energy per bit (EW) and switching current density (Jc), as a function of resistance-area product (RA) (hence MgO thickness) in magnetic tunnel junction cells used for magnetoresistive random access memory (MRAM). EW increases with RA, while Jc decreases with increasing RA for both switching directions. The results are discussed in terms of RA optimization for low write energy and current drive capability (hence density) of the MRAM cells. Switching times <2 ns and write energies <0.3 pJ are demonstrated for 135 nm×65 nm CoFeB/MgO/CoFeB devices.
Carbon nanotube chains in a shape memory polymer/carbon black composite: To significantly reduce the electrical resistivity
Authors: Yu Kai , Zhang Zhichun , Liu Yanju , Leng Jinsong
Published: February 2011

Instead of individually aligned along the external electric field, the carbon nanotubes (CNTs) were electrically induced into aligned chains in a shape memory polymer (SMP)/carbon black (CB) composite, which would serve as long-distance conductive channels to bridge the CB aggregations. Compared with SMP composites with randomly filled CNTs, the electrical resistivity in those with chained CNTs was reduced for more than 100 times. The fabricated conductive SMP composites could be actuated by a low electrical power.
Edge-enhanced Raman scattering effect from Au deposited nanoedge array
Authors: Liu Li , Shao Mingwang , Cheng Liang , Zhuo Shujuan , Que Ronghui , Lee Shuit Tong
Published: February 2011

Edge-enhanced Raman scattering effect was demonstrated on nanoedge array, depositing Au film on the profile of anodized aluminum oxide template with the pore diameter of 30 nm and the channel length of 50 μm. The results showed a prominent superior Raman enhancement from the nanoedge array on the highly reproducible, uniform, and sensitive substrate with an enhancement factor of 107, which suggested the potential applications in ultrasensitive edge-enhanced Raman detection.
Stabilizing and activating dopants in ⟨112⟩ silicon nanowires by alkene adsorptions: A first-principles study
Authors: Xu H. , Yang X. B. , Zhang C. , Lu A. J. , Zhang R. Q.
Published: February 2011

The B dopant stability and doping level tunability of ⟨112⟩ silicon nanowires (SiNWs) with alkene adsorption are revealed based on first-principles calculations. It is found that the alkenyl chains favor the middle location of (111) facet, and the B dopants prefer to locate at (110) facet of the ⟨112⟩ SiNW. Interestingly, the B doping levels are activated upon an alkene adsorption which introduces an intermediate energy level. This finding sheds light on how SiNWs can achieve effective doping.
Transcription factor genes
Smad4
and
Gata4
cooperatively regulate cardiac valve development
Authors: Moskowitz Ivan P. , Wang Jun , Peterson Michael A. , Pu William T. , Mackinnon Alexander C. , Oxburgh Leif , Chu Gerald C. , Sarkar Molly , Berul Charles , Smoot Leslie , Robertson Elizabeth J. , Schwartz Robert , Seidman Jonathan G. , Seidman Christine E.
Published: February 2011

We report that the dominant human missense mutations G303E and G296S in
GATA4
, a cardiac-specific transcription factor gene, cause atrioventricular septal defects and valve abnormalities by disrupting a signaling cascade involved in endocardial cushion development. These
GATA4
missense mutations, but not a mutation causing secundum atrial septal defects (S52F), demonstrated impaired protein interactions with SMAD4, a transcription factor required for canonical bone morphogenetic protein/transforming growth factor-β (
BMP
/
TGF-β
) signaling.
Gata4
and
Smad4
genetically interact in vivo: atrioventricular septal defects result from endothelial-specific
Gata4
and
Smad4
compound haploinsufficiency. Endothelial-specific knockout of
Smad4
caused an absence of valve-forming activity:
Smad4
-deficient endocardium was associated with acellular endocardial cushions, absent epithelial-to-mesenchymal transformation, reduced endocardial proliferation, and loss of
Id2
expression in valve-forming regions. We show that Gata4 and Smad4 cooperatively activated the
Id2
promoter, that human
GATA4
mutations abrogated this activity, and that
Id2
deficiency in mice could cause atrioventricular septal defects. We suggest that one determinant of the phenotypic spectrum caused by human
GATA4
mutations is differential effects on GATA4/SMAD4 interactions required for endocardial cushion development.
Global CO
2
rise leads to reduced maximum stomatal conductance in Florida vegetation
Authors: Lammertsma Emmy I. , Boer Hugo Jan de , Dekker Stefan C. , Dilcher David L. , Lotter André F. , Wagner-Cremer Friederike
Published: February 2011

A principle response of C3 plants to increasing concentrations of atmospheric CO
2
(

CO
2

) is to reduce transpirational water loss by decreasing stomatal conductance (

g
s

) and simultaneously increase assimilation rates. Via this adaptation, vegetation has the ability to alter hydrology and climate. Therefore, it is important to determine the adaptation of vegetation to the expected anthropogenic rise in

CO
2

. Short-term stomatal opening–closing responses of vegetation to increasing

CO
2

are described by free-air carbon enrichments growth experiments, and evolutionary adaptations are known from the geological record. However, to date the effects of decadal to centennial

CO
2

perturbations on stomatal conductance are still largely unknown. Here we reconstruct a 34% (±12%) reduction in maximum stomatal conductance (

g
smax

) per 100 ppm

CO
2

increase as a result of the adaptation in stomatal density (
D
) and pore size at maximal stomatal opening (

a
max

) of nine common species from Florida over the past 150 y. The species-specific

g
smax

values are determined by different evolutionary development, whereby the angiosperms sampled generally have numerous small stomata and high

g
smax

, and the conifers and fern have few large stomata and lower

g
smax

. Although angiosperms and conifers use different
D
and

a
max

adaptation strategies, our data show a coherent response in

g
smax

to

CO
2

rise of the past century. Understanding these adaptations of C3 plants to rising

CO
2

after decadal to centennial environmental changes is essential for quantification of plant physiological forcing at timescales relevant for global warming, and they are likely to continue until the limits of their phenotypic plasticity are reached.
Climate forcing due to optimization of maximal leaf conductance in subtropical vegetation under rising CO
2
Authors: de Boer Hugo Jan , Lammertsma Emmy I. , Wagner-Cremer Friederike , Dilcher David L. , Wassen Martin J. , Dekker Stefan C.
Published: February 2011

Plant physiological adaptation to the global rise in atmospheric CO
2
concentration (

CO
2

) is identified as a crucial climatic forcing. To optimize functioning under rising

CO
2

, plants reduce the diffusive stomatal conductance of their leaves (
g
s
) dynamically by closing stomata and structurally by growing leaves with altered stomatal densities and pore sizes. The structural adaptations reduce maximal stomatal conductance (
g
smax
) and constrain the dynamic responses of
g
s
. Here, we develop and validate models that simulate structural stomatal adaptations based on diffusion of

CO
2

and water vapor through stomata, photosynthesis, and optimization of carbon gain under the constraint of a plant physiological cost of water loss. We propose that the ongoing optimization of
g
smax
is eventually limited by species-specific limits to phenotypic plasticity. Our model reproduces observed structural stomatal adaptations and predicts that adaptation will continue beyond double

CO
2

. Owing to their distinct stomatal dimensions, angiosperms reach their phenotypic response limits on average at 740 ppm and conifers on average at 1,250 ppm

CO
2

. Further, our simulations predict that doubling today's

CO
2

will decrease the annual transpiration flux of subtropical vegetation in Florida by ≈60 W·m
−2
. We conclude that plant adaptation to rising

CO
2

is altering the freshwater cycle and climate and will continue to do so throughout this century.
High-performance photoresponse from single-walled carbon nanotube–zinc oxide heterojunctions
Authors: Chang Jingbo , Najeeb Choolakadavil Khalid , Lee Jae-Hyeok , Lee Minsu , Kim Jae-Ho
Published: February 2011

Photoactive materials consisting of single-walled carbon nanotube (SWNT)–zinc oxide (ZnO) heterojunctions targeted for optoelectronic applications are investigated in terms of photoresponse and photovoltaic effects. The devices based on SWNT–ZnO heterojunction films are fabricated by two step processes: first, a well aligned SWNT monolayer is deposited on an oxide substrate by the Langmuir–Blodgett (LB) technique; then a ZnO film prepared by filtration of ZnO nanowire solution is transferred onto the SWNT film to form SWNT–ZnO junctions. The SWNT–ZnO heterojunction demonstrates faster photoresponse time (2.75 s) up to 18 times and photovoltaic efficiency (1.33 nA) up to 4 times higher than that of only a ZnO device. Furthermore, the mechanisms of UV sensitivity enhancement and photovoltaic effects are explained according to the high electron mobility in the SWNT–ZnO heterojunctions.
Absorptive and conductive cavity cathode with silver nanoparticles for low-reflection organic light-emitting devices
Authors: Chiu Tien-Lung , Lee Jiun-Haw , Hsiao Yi-Peng , Lin Chi-Feng , Chao Chun-Chieh , Leung Man-Kit , Wan De-Hui , Chen Hsuen-Li , Ho Hsin-Chia
Published: February 2011

We have successfully fabricated a low-reflection organic light-emitting diode (LR-OLED) by replacing the highly reflective Al cathode of a conventional OLED with a Fabry–Pérot (FP) cavity cathode, which is simultaneously responsible for absorption, plasmonic absorption and destructive interference. The FP cavity cathode consisted of a front semi-transparent double thin metal layer (Al/Ag), an inserted organometallic black layer (BL) in the middle and a highly reflective Al mirror. The organometallic BL contained a high-mobility electron transport and broadband absorptive organic matrix, N,N′-bis(2,6-diisopropylphenyl)-1,7-bis(4-methoxy-phenyl)perylene-3,4,9,10-tetracarboxydiimide (MPPDI), and Ag-nanoparticle (NP) dopants which contributed not only to the plasmonic absorption but also to the metallic conductivity. By adjusting the thickness and Ag-NP concentration of the organometallic BL, one can optimize the destructive interference cavity effect. LR-OLEDs fabricated using the aforementioned characteristics of the Ag-NP yielded superior electrical performance and low reflection across almost the entire visible spectrum. With the exemption of surface reflection (air/glass ∼4%), a lowest reflection of 0% near 750 nm and an average reflection of 1.39% for the entire visible spectrum were obtained for a LR-OLED with a 65 nm organometallic BL (mixing ratio of MPPDI : Ag = 10 : 1). With the additional structural cavity cathode, the LR-OLEDs nonetheless exhibited similar electrical performances and continuous operational lifetimes to those of control devices with a traditional highly reflective Al cathode.
The influence of additional electrons on memory effect in nitrogen at low pressures
Authors: Nesic Nikola T , Pejovic Momcilo M , Pejovic Milic M , Zivanovic Emilija N
Published: February 2011

Memory effect in nitrogen based on experimental data of electrical breakdown time delay as a function of afterglow period in the presence of additional electrons has been investigated. The additional electrons were supplied as a result of extraction from the auxiliary electrode pair or nitrogen irradiation with the radioactive sourceof low activity. The results show that these electrons have an important role in the recombination of positive ions formed in mutual metastable molecules' collisions and collisions between metastable and highly vibrationally excited molecules in the early afterglow. As a consequence of the ion–electron recombination N(4S) atoms are formed which, as well as N(4S) atoms formed in previous discharge, have a significant influence on the memory effect in late afterglow. The presence of N(4S) atoms in the late afterglow is tracked by monitoring the secondary emission which they induce via catalytic recombination on the cathode of a nitrogen-filled tube. Also, it has been shown that the contribution of secondary electrons which originate from N(4S) atoms and Compton electrons when the radioactive source is and isn't present can be distinguished.
Investigating the dependence of the temperature of high-intensity discharge (HID) lamp electrodes on the operating frequency by pyrometric measurements
Authors: Reinelt J , Westermeier M , Ruhrmann C , Bergner A , Awakowicz P , Mentel J
Published: February 2011

Phase-resolved temperature distributions are determined along a rod-shaped tungsten electrode, by which an ac arc is operated within a model lamp filled with argon. Switched dc and sinusoidal currents are applied with amplitudes of several amperes and operating frequencies being varied between 10 Hz and 10 kHz. The temperature is deduced from the grey body radiation of the electrode being recorded with a spectroscopic measuring system. Phase-resolved values of the electrode tip temperature T
tip and of the power input P
in are determined comparing the measured temperature distributions with the integral of the one-dimensional heat balance with these parameters as integration constants. They are supplemented by phase-resolved measurements of the sum of cathode and anode fall called the electrode sheath voltage. If a switched dc current is applied it is found that both quantities are within the cathodic phase only marginally higher than for a cathode being operated with a dc current. T
tip and P
in start to decrease for low currents and to increase for high currents at the beginning of the anodic phase. But with increasing operating frequency the deviations from the cathodic phase are reduced until they cannot be resolved for frequencies of several kHz. A more pronounced modulation, but the same tendencies, is observed with a sinusoidal current waveform. For 10 kHz a diffuse arc attachment with an almost phase-independent electrode tip temperature, which deviates only marginally from that of a dc cathode, and an electrode sheath voltage proportional to the arc current is established with both current waveforms.