bluuebunny/crossref_metadata_2025 huggingface dataset:
Negative ions of p-nitroaniline: Photodetachment, collisions, and ab initio calculations
Authors: Smith Byron H. , Buonaugurio Angela , Chen Jing , Collins Evan , Bowen Kit H. , Compton Robert N. , Sommerfeld Thomas
Published: June 2013

The structures of parent anion, M−, and deprotonated molecule, [M−H]−, anions of the highly polar p-nitroaniline (pNA) molecule are studied experimentally and theoretically. Photoelectron spectroscopy (PES) of the parent anion is employed to estimate the adiabatic electron affinity (EAa = 0.75 ± 0.1 eV) and vertical detachment energy (VDE = 1.1 eV). These measured energies are in good agreement with computed values of 0.73 eV for the EAa and the range of 0.85 to 1.0 eV for the VDE at the EOM-CCSD/Aug-cc-pVTZ level. Collision induced dissociation (CID) of deprotonated pNA, [pNA − H]−, with argon yielded [pNA − H − NO]− (i.e., rearrangement to give loss of NO) with a threshold energy of 2.36 eV. Calculations of the energy difference between [pNA − H]− and [pNA − H − NO]− give 1.64 eV, allowing an estimate of a 0.72 eV activation barrier for the rearrangement reaction. Direct dissociation of [pNA − H]− yielding ${\rm NO}_2^ -$ NO 2− occurs at a threshold energy of 3.80 eV, in good agreement with theory (between 3.39 eV and 4.30 eV). As a result of the exceedingly large dipole moment for pNA (6.2 Debye measured in acetone), we predict two dipole-bound states, one at ∼110 meV and an excited state at 2 meV. No dipole-bound states are observed in the photodetachment experiments due the pronounced mixing between states with dipole-bound and valence character similar to what has been observed in other nitro systems. For the same reason, dipole-bound states are expected to provide highly efficient “doorway states” for the formation of the pNA− valence anion, and these states should be observable as resonances in the reverse process, that is, in the photodetachment spectrum of pNA− near the photodetachment threshold.
Experimental evidence for mobile luminescence center mobility on partial dislocations in 4H-SiC using hyperspectral electroluminescence imaging
Authors: Caldwell Joshua D. , Giles Alexander , Lepage Dominic , Carrier Dominic , Moumanis Khalid , Hull Brett A. , Stahlbush Robert E. , Myers-Ward Rachael L. , Dubowski Jan J. , Verhaegen Marc
Published: June 2013

We report on the formation, motion, and concentration of localized green emission centers along partial dislocations (PDs) bounding recombination-induced stacking faults (RISFs) in 4H-SiC pin diodes. Electroluminescence imaging depicted the motion of these green emitting point defects during forward bias operation along carbon-core PDs that bound the RISFs. Following high temperature annealing, these green emitting point defects did not contract with the PDs, but remained in the final location during the expansion. This implies that the motion of these green emitting point dislocations is enabled through a recombination-enhanced motion, similar to the process for RISF expansion and contraction within SiC.
Verification of band offsets and electron effective masses in GaAsN/GaAs quantum wells: Spectroscopic experiment versus 10-band k·p modeling
Authors: Ryczko K. , Sęk G. , Sitarek P. , Mika A. , Misiewicz J. , Langer F. , Höfling S. , Forchel A. , Kamp M.
Published: June 2013

Optical transitions in GaAs1−xNx/GaAs quantum wells (QWs) have been probed by two complementary techniques, modulation spectroscopy in a form of photoreflectance and surface photovoltage spectroscopy. Transition energies in QWs of various widths and N contents have been compared with the results of band structure calculations based on the 10-band k·p Hamiltonian. Due to the observation of higher order transitions in the measured spectra, the band gap discontinuities at the GaAsN/GaAs interface and the electron effective masses could be determined, both treated as semi-free parameters to get the best matching between the theoretical and experimental energies. We have obtained the chemical conduction band offset values of 86% for x = 1.2% and 83% for x = 2.2%, respectively. For these determined band offsets, the electron effective masses equal to about 0.09 mo in QWs with 1.2% N and 0.15 mo for the case of larger N content of 2.2%.
A high-power 626 nm diode laser system for Beryllium ion trapping
Authors: Ball H. , Lee M. W. , Gensemer S. D. , Biercuk M. J.
Published: June 2013

We describe a high-power, frequency-tunable, external cavity diode laser system near 626 nm useful for laser cooling of trapped 9Be+ ions. A commercial single-mode laser diode with rated power output of 170 mW at 635 nm is cooled to ≈−31°C, and a single longitudinal mode is selected via the Littrow configuration. In our setup, involving two stages of thermoelectric cooling, we are able to obtain ≈130 mW near 626 nm, sufficient for efficient frequency doubling to the required Doppler cooling wavelengths near 313 nm in ionized Beryllium. In order to improve nonlinear frequency conversion efficiency, we achieve larger useful power via injection locking of a slave laser. In this way the entirety of the slave output power is available for frequency doubling, while analysis may be performed on the master output. We believe that this simple laser system addresses a key need in the ion trapping community and dramatically reduces the cost and complexity associated with Beryllium ion trapping experiments.
Design and operation of a rotating drum radio frequency plasma reactor for the modification of free nanoparticles
Authors: Shearer Jeffrey C. , Fisher Ellen R.
Published: June 2013

A rotating drum rf plasma reactor was designed to functionalize the surface of nanoparticles and other unusually shaped substrates through plasma polymerization and surface modification. This proof-of-concept reactor design utilizes plasma polymerized allyl alcohol to add OH functionality to Fe2O3 nanoparticles. The reactor design is adaptable to current plasma hardware, eliminating the need for an independent reactor setup. Plasma polymerization performed on Si wafers, Fe2O3 nanoparticles supported on Si wafers, and freely rotating Fe2O3 nanoparticles demonstrated the utility of the reactor for a multitude of processes. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to characterize the surface of the substrates prior to and after plasma deposition, and scanning electron microscopy was used to verify that no extensive change in the size or shape of the nanoparticles occurred because of the rotating motion of the reactor. The reactor design was also extended to a non-depositing NH3 plasma modification system to demonstrate the reactor design is effective for multiple plasma processes.
Field-programmable gate array based arbitrary signal generator and oscilloscope for use in slow light and storage of light experiments
Authors: Nikolić Stanko N. , Batić Viktor , Panić Bratimir , Jelenković Branislav M.
Published: June 2013

We present a field-programmable gate array (FPGA) based device that simultaneously generates two arbitrary analog voltage signals with the maximum sample rate of 1.25 MHz and acquires two analog voltage signals with the maximum sample rate of 2.5 MHz. All signals are synchronized with internal FPGA clock. The personal computer application developed for controlling and communicating with FPGA chip provides the shaping of the output signals by mathematical expressions and real-time monitoring of the input signals. The main advantages of FPGA based digital-to-analog and analog-to-digital cards are high speed, rapid reconfigurability, friendly user interface, and low cost. We use this module in slow light and storage of light experiments performed in Rb buffer gas cell.
Influence of surface null potential on nonvolatile bistable resistive switching memory behavior of dilutely aluminum doped ZnO thin film
Authors: Shirolkar Mandar M. , Hao Changshan , Yin Shiliu , Li Ming , Wang Haiqian
Published: June 2013

We report a correlation between surface null potential and bistable resistive switching effect in dilutely Al-doped ZnO nearly transparent thin film. The nearly symmetrical bistable resistive switching was observed at low operating potential (±1 V) with good repeatability and stability, driven by surface null potential. We report that above null potential, oxygen vacancies in the proximity of aluminum provide systematic development of conducting paths. While, the switching effect was also observed to be dopant driven in the proximity to ±1 V. The phenomenon was explained using migration of Al3+ in ZnO matrix, which dominates over oxygen vacancies.
Gain compression and its dependence on output power in quantum dot lasers
Authors: Zhukov A. E. , Maximov M. V. , Savelyev A. V. , Shernyakov Yu. M. , Zubov F. I. , Korenev V. V. , Martinez A. , Ramdane A. , Provost J.-G. , Livshits D. A.
Published: June 2013

The gain compression coefficient was evaluated by applying the frequency modulation/amplitude modulation technique in a distributed feedback InAs/InGaAs quantum dot laser. A strong dependence of the gain compression coefficient on the output power was found. Our analysis of the gain compression within the frame of the modified well-barrier hole burning model reveals that the gain compression coefficient decreases beyond the lasing threshold, which is in a good agreement with the experimental observations.
Aspects of collisionless magnetic reconnection in asymmetric systems
Authors: Hesse Michael , Aunai Nicolas , Zenitani Seiji , Kuznetsova Masha , Birn Joachim
Published: June 2013

Asymmetric reconnection is being investigated by means of particle-in-cell simulations. The research has two foci: the direction of the reconnection line in configurations with nonvanishing magnetic fields; and the question why reconnection can be faster if a guide field is added to an otherwise unchanged asymmetric configuration. We find that reconnection prefers a direction, which maximizes the available magnetic energy, and show that this direction coincides with the bisection of the angle between the asymptotic magnetic fields. Regarding the difference in reconnection rates between planar and guide field models, we demonstrate that a guide field can provide essential confinement for particles in the reconnection region, which the weaker magnetic field in one of the inflow directions cannot necessarily provide.
Comparison of kinetic and extended magnetohydrodynamics computational models for the linear ion temperature gradient instability in slab geometry
Authors: Schnack D. D. , Cheng J. , Barnes D. C. , Parker S. E.
Published: June 2013

We perform linear stability studies of the ion temperature gradient (ITG) instability in unsheared slab geometry using kinetic and extended magnetohydrodynamics (MHD) models, in the regime k∥/k⊥≪1. The ITG is a parallel (to B) sound wave that may be destabilized by finite ion Larmor radius (FLR) effects in the presence of a gradient in the equilibrium ion temperature. The ITG is stable in both ideal and resistive MHD; for a given temperature scale length LTi0, instability requires that either k⊥ρi or ρi/LTi0 be sufficiently large. Kinetic models capture FLR effects to all orders in either parameter. In the extended MHD model, these effects are captured only to lowest order by means of the Braginskii ion gyro-viscous stress tensor and the ion diamagnetic heat flux. We present the linear electrostatic dispersion relations for the ITG for both kinetic Vlasov and extended MHD (two-fluid) models in the local approximation. In the low frequency fluid regime, these reduce to the same cubic equation for the complex eigenvalue ω=ωr+iγ. An explicit solution is derived for the growth rate and real frequency in this regime. These are found to depend on a single non-dimensional parameter. We also compute the eigenvalues and the eigenfunctions with the extended MHD code NIMROD, and a hybrid kinetic δf code that assumes six-dimensional Vlasov ions and isothermal fluid electrons, as functions of k⊥ρi and ρi/LTi0 using a spatially dependent equilibrium. These solutions are compared with each other, and with the predictions of the local kinetic and fluid dispersion relations. Kinetic and fluid calculations agree well at and near the marginal stability point, but diverge as k⊥ρi or ρi/LTi0 increases. There is good qualitative agreement between the models for the shape of the unstable global eigenfunction for LTi0/ρi=30 and 20. The results quantify how far fluid calculations can be extended accurately into the kinetic regime. We conclude that for the linear ITG problem in slab geometry with unsheared magnetic field when k∥/k⊥≪1, the extended MHD model may be a reliable physical model for this problem when ρi/LTi0<10−2 and k⊥ρi<0.2.
The plasmoid instability during asymmetric inflow magnetic reconnection
Authors: Murphy Nicholas A. , Young Aleida K. , Shen Chengcai , Lin Jun , Ni Lei
Published: June 2013

Theoretical studies of the plasmoid instability generally assume that the reconnecting magnetic fields are symmetric. We relax this assumption by performing two-dimensional resistive magnetohydrodynamic simulations of the plasmoid instability during asymmetric inflow magnetic reconnection. Magnetic asymmetry modifies the onset, scaling, and dynamics of this instability. Magnetic islands develop preferentially into the weak magnetic field upstream region. Outflow jets from individual X-points impact plasmoids obliquely rather than directly as in the symmetric case. Consequently, deposition of momentum by the outflow jets into the plasmoids is less efficient, the plasmoids develop net vorticity, and shear flow slows down secondary merging between islands. Secondary merging events have asymmetry along both the inflow and outflow directions. Downstream plasma is more turbulent in cases with magnetic asymmetry because islands are able to roll around each other after exiting the current sheet. As in the symmetric case, plasmoid formation facilitates faster reconnection for at least small and moderate magnetic asymmetries. However, when the upstream magnetic field strengths differ by a factor of 4, the reconnection rate plateaus at a lower value than expected from scaling the symmetric results. We perform a parameter study to investigate the onset of the plasmoid instability as a function of magnetic asymmetry and domain size. There exist domain sizes for which symmetric simulations are stable but asymmetric simulations are unstable, suggesting that moderate magnetic asymmetry is somewhat destabilizing. We discuss the implications for plasmoid and flux rope formation in solar eruptions, laboratory reconnection experiments, and space plasmas. The differences between symmetric and asymmetric simulations provide some hints regarding the nature of the three-dimensional plasmoid instability.
Morphology and chain aggregation dependence of optical gain in thermally annealed films of the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene]
Authors: Lampert Zach E. , Lappi Simon E. , Papanikolas John M. , Lewis Reynolds C. , Osama Aboelfotoh M.
Published: June 2013

Aggregate formation in conjugated polymer films is one of the most important phenomena thought to influence the photophysical properties of optical devices based on these materials. In the current work, we report the results of a detailed investigation on the morphology and chain aggregation dependence of optical gain in spin-coated thin films of the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV). Extensive gain measurements are performed using the variable stripe length technique with picosecond pulse excitation. The polymer morphology and extent of aggregate formation in the films are controlled by thermal annealing, which is relevant to the fabrication and optimization of conjugated polymer-based optical devices. The aggregation state of the polymer chains increases with the annealing temperature, which results in a decrease in luminescence efficiency at low excitation density (≤1018 cm−3). However, the increase in aggregate formation with increasing annealing temperature does not significantly alter the optical gain; very large gain coefficients are still achieved in films containing a relatively large fraction of aggregates. Although the largest gain coefficients, 450 cm−1, are observed for as-cast (non-annealed) MEH-PPV films, very large gain coefficients of 315 and 365 cm−1 are also demonstrated for MEH-PPV films annealed at 60 and 80 °C, respectively, in spite of the enhanced packing morphology and conformational order of the polymer chains. These results are contrary to the commonly held view that aggregate formation has a detrimental effect on the amplified spontaneous emission behavior of polymer-based devices operating in the stimulated emission regime, as would be characteristic of lasers and optical amplifiers. Moreover, because aggregates promote favorable charge transport properties, our data have important implications for future development of electrically driven polymer lasers; improving carrier mobility through controlled increases in chain aggregation should provide a viable path for enhancing injection efficiency without significantly degrading optical gain.
Uniaxial anisotropy induced in 57Fe/Co/Al multilayers
Authors: Jain Vishal , Jani Snehal , Lakshmi N. , Sebastian V. , Reddy V. R. , Venugopalan K. , Gupta Ajay
Published: June 2013

The magnetic properties of 57Fe/Co/Al multilayers with 20 and 40 trilayers, deposited on Si (100) substrate using ion beam sputtering, are reported here. X-ray reflectivity and X-ray diffraction studies indicate the formation of good quality films with preferential growth along the (110) direction. Conversion electron Mössbauer spectra show considerable inter-mixing between the layers and the formation of Fe-Al/Fe-Co-Al phases. The samples are extremely soft with coercivities ≤0.48 × 103 A/m, exhibit strong in-plane uniaxial anisotropy and calculations show that they possess a high ferromagnetic resonance frequency of ∼2 GHz. The saturation magnetization value of 1.80 × 106 A/m is comparable with that obtained in multilayer samples with much higher content of Co. The combination of magnetic properties in these multilayers thus makes them ideal candidates for high frequency device applications.
Three-dimensional temperature imaging around a gold microwire
Authors: Bon Pierre , Belaid Nadia , Lagrange Denis , Bergaud Christian , Rigneault Hervé , Monneret Serge , Baffou Guillaume
Published: June 2013

We report on the temperature mapping around a resistively heated gold microwire. The temperature is determined by measuring the thermal-induced distortion of an incident optical wavefront crossing the system. The optical technique we introduce herein allows, in addition to 3-dimensional temperature measurements, a retrieval of the heat source density at optical resolution. Experimental results are supported by finite element simulations and electric measurements. Applications are envisioned in microelectronics, microfluidics, or nanochemistry.
Hafnia-plugged microcavities for thermal stability of selective emitters
Authors: Lee Heon-Ju , Smyth Katherine , Bathurst Stephen , Chou Jeffrey , Ghebrebrhan Michael , Joannopoulos John , Saka Nannaji , Kim Sang-Gook
Published: June 2013

Two-dimensional arrays of micro-cavities effectively control photon motion and selectively emit radiation tailored to the preferred bandgap of photovoltaic (PV) cells, thus enhancing the efficiency of thermophotovoltaic energy conversion. At the high operating temperatures, however, the micro- and nano-patterned structures of the selective emitters quickly lose their integrity––obliterating the tight tolerances required for precise spectral control. Even if oxidation, recrystallization, and grain growth could be avoided with single-crystal tungsten (W) selective emitters with vacuum packaging, surface diffusion, evaporation, and re-condensation are not avoidable in long-term operation at high temperatures. The concept of a planar array of plugged micro-cavities to suppress the curvature-dependent thermal degradation modes is proposed and tested. Based on scale-accelerated failure tests of silicon devices, the lifetime of W selective emitters operating at 1100 K is estimated to be at least 30 yr.
Multiphoton polymerization using optical trap assisted nanopatterning
Authors: Leitz Karl-Heinz , Tsai Yu-Cheng , Flad Florian , Schäffer Eike , Quentin Ulf , Alexeev Ilya , Fardel Romain , Arnold Craig B. , Schmidt Michael
Published: June 2013

In this letter, we show the combination of multiphoton polymerization and optical trap assisted nanopatterning (OTAN) for the additive manufacturing of structures with nanometer resolution. User-defined patterns of polymer nanostructures are deposited on a glass substrate by a 3.5 μm polystyrene sphere focusing IR femtosecond laser pulses, showing minimum feature sizes of λ/10. Feature size depends on the applied laser fluence and the bead surface spacing. A finite element model describes the intensity enhancement in the microbead focus. The results presented suggest that OTAN in combination with multiphoton processing is a viable technique for additive nanomanufacturing with sub-diffraction-limited resolution.
Propagation of acoustic waves in a metamaterial with a refractive index of near zero
Authors: Park Choon Mahn , Lee Sang Hun
Published: June 2013

A metamaterial system with a refractive index of near zero for acoustic wave is realized. The designed system, which uses Helmholtz resonators, is analyzed using the equivalent circuit theory. Through the simulation and the experiment, we observed a large phase velocity in the metamaterial and a concentration of the energy density in the narrow normal waveguide directly coupled to the metamaterial. This is different to the metamaterial for the electromagnetic wave, because the concentration of energy density of the electromagnetic wave occurs in the metamaterial inside. The acoustic metamaterial system can be applied to the development of device for the acoustic energy concentrator and the acoustic filter.
Shock-ramp compression: Ramp compression of shock-melted tin
Authors: Seagle C. T. , Davis J.-P. , Martin M. R. , Hanshaw H. L.
Published: June 2013

A technique has been developed at the Sandia Z Accelerator using a magnetically driven flyer plate with a double-ramp pulse shape to generate in a test sample a steady shock followed 10–100 ns later by a quasi-isentropic ramped compression wave. Based on velocity data from multiple samples of differing thicknesses, a technique based on backward minimization is presented that allows the determination of material response along an elevated isentrope through the shock state. Data on quasi-isentropically compressed shock-melted tin indicate a stiffer response than currently available equation-of-state models.
Electromagnetic particle-in-cell verification of improving high-power microwave window breakdown thresholds by resonant magnetic field
Authors: Cheng Guoxin , Liu Lie
Published: June 2013

High-power microwave driven vacuum dielectric window breakdown is found to be suppressed by external magnetic field with gyrofrequency Ω = eB/m close to angular frequency ω of rf electric field. This letter gives a particle-in-cell demonstration of the increasing of breakdown thresholds by such magnetic field. It is found that magnetic field with Ω ∼ ω mitigates the multipactor effect. Its saturation process occurs at upper boundary of the susceptibility diagram instead of the lower one. This decreases the dc electric field built on dielectric surface. The electron-dielectric interaction rate is lowered, especially in the half rf period with Erf × B force pointing out of the dielectric surface. The resulting flashover time delay is prolonged. Thereby, the power handling capability of the dielectric window is enhanced.
Magnetic memory effect in multiferroic K3Fe5F15 and K3Cr2Fe3F15
Authors: Jagličić Z. , Pajić D. , Trontelj Z. , Dolinšek J. , Jagodič M.
Published: June 2013

The fluorides K3Fe5F15 and K3Cr2Fe3F15 are known as multiferroic materials. Here we report the detection of a magnetic memory effect in these materials and its dependence on temperature and aging time. We succeeded in writing, reading, and deleting 3-bits digital information in these systems. These results show that in addition to their already known magneto-electric multiferroic properties, K3Fe5F15 and K3Cr2Fe3F15 also possess a new functionality: they can be used as materials for a thermal memory cell.
Electrical characterization of In0.53Ga0.47As/In0.52Al0.48As high electron mobility transistors on plastic flexible substrate under mechanical bending conditions
Authors: Shi J. , Wichmann N. , Roelens Y. , Bollaert S.
Published: June 2013

InAlAs/InGaAs high electron mobility transistors (HEMTs) have been transferred onto polyimide flexible substrate. By means of epitaxial layer optimization, kink effect in HEMT on flexible substrate, which existed in our previous work, has been suppressed. The value of maximum drain current reaches 580 mA/mm and high cut-off frequencies fT = 160 GHz, fmax = 290 GHz are obtained for unbent status. The effect of mechanical bending conditions on electrical performance has been also investigated in static and dynamic regimes. This study indicates that electrical characteristics are weakly affected by bending induced strain. These bending mechanical tests demonstrate the viable flexibility of the devices.
Influence of film thickness and air exposure on the transport gap of manganese phthalocyanine
Authors: Haidu F. , Fechner A. , Salvan G. , Gordan O. D. , Fronk M. , Lehmann D. , Mahns B. , Knupfer M. , Zahn D. R. T.
Published: June 2013

The interface formation between manganese phthalocyanine (MnPc) and cobalt was investigated combining ultraviolet photoelectron spectroscopy and inverse photoelectron spectroscopy. The transport band gap of the MnPc increases with the film thickness up to a value of (1.2 ± 0.3) eV while the optical band gap as determined from spectroscopic ellipsometry amounts to 0.5 eV. The gap values are smaller compared to other phthalocyanines due to metallic Mn 3d states close to the Fermi level. The transport band gap was found to open upon air exposure as a result of the disappearance of the occupied 3d electronic states.
Relating to the Sea: Enlivening the Ocean as an Actor in Eastern Sri Lanka
Authors: Lehman Jessica S
Published: June 2013

Elements deemed part of ‘nature’ or the ‘environment’ have long been considered factors in political and social realities, but recent work by environmental historians, feminists, poststructuralists, and particularly posthumanists calls for them to be understood as actors. In this paper I build a case for considering the ocean as an actor on Sri Lanka's east coast, by bringing concepts around relationality and nonhuman agency into conversation with social theories of the sea and with the lived experiences of coastal residents. The ocean occupies a dynamic and central role on Sri Lanka's East coast, as demonstrated through daily practices and its centrality in the area's armed conflict, as well as by the devastation wreaked by the 2004 tsunami. By understanding the ocean as an actor it is possible to gain insight into the intersections of various phenomena, such as armed conflict and natural disaster, and to amplify the voices of those who occupy space closest to those intersections.
Synthesis, Structural Characterisation, and Preliminary Evaluation of Non-Indolin-2-one-based Angiogenesis Inhibitors Related to Sunitinib (Sutent®)
Authors: Sudta Pichit , Kirk Nicholas , Bezos Anna , Gurlica Anthony , Mitchell Rhys , Weber Thomas , Willis Anthony C. , Prabpai Samran , Kongsaeree Palangpon , Parish Christopher R. , Suksamrarn Sunit , Kelso Michael J.
Published: June 2013

The indolin-2-one fused-ring system and the 2,4-dimethylpyrrole unit represent key structural motifs in the anticancer drug sunitinib (Sutent®) and predecessor angiogenesis inhibitors that have undergone anticancer clinical trials (e.g. semaxanib, SU5416). In pursuit of novel anti-angiogenic scaffolds, we were interested in identifying whether the indolin-2-one group in these structures could be modified without losing activity. This paper describes novel condensation chemistry used to prepare a test series of (E)- and (Z)-alkenes related to SU5416 that retain the 2,4-dimethylpyrrole unit while incorporating ring-opened indolin-2-ones. Unique structural characteristics were identified in the compounds, such as intramolecular hydrogen bonds in the (Z)-alkenes, and several examples were shown to possess significant anti-angiogenic activity in a rat aorta in vitro model of angiogenesis. The work demonstrates that the indolin-2-one moiety is not an absolute requirement for angiogenesis inhibition in the sunitinib/SU5416 class.
Simulating the vertical transition of soil textural layers in north-western China with a Markov chain model
Authors: Li Danfeng , Shao Ming'an
Published: June 2013

The heterogeneity of textures in soil profiles is important for quantifying the movement of water and solutes through soil. Soil-profile textures to a depth of 300 cm were investigated at 100 sites in a 100-km2 area in the central region of the Heihe River system, where oases coexist with widespread deserts and wetland. The probability distribution of textural-layer thickness was quantified. The vertical transition of the soil textural layers was characterised by a Markov chain–log-normal distribution (MC-LN) model based on the probability of one textural type transitioning to another. Nine types of textural layers were observed: sand, loamy sand, sandy loam, silt loam, loam, clay loam, silty clay loam, silty clay, and clay. Sand was the most frequent in the profiles, whereas silt loam and clay were rare. The layers of sand and silty clay were relatively thick, and the layers of loam and clay were relatively thin. The coefficients of variation ranged from 36–87%, indicating moderate variation in the layer thickness of each textural type. The soil profile was characterised as a log-normal distribution. A χ2 test verified the Markov characteristic and the stability of the vertical change of soil textural layers. Realisations of the soil textural profiles were generated by the MC-LN model. A Monte Carlo simulation indicated that the simulated mean layer thickness of each textural type agreed well with the corresponding field observations. Element values of the transition probability matrix of the textural layers simulated by the MC-LN model deviated <12.6% from the measured values, excluding the data from the layers of clay and silt loam. The main combinations of upper to lower textural layers in the study area were loamy sand and sand (or sandy loam), sandy loam and sand (or loamy sand and loam), loam and clay loam, clay loam (or silty clay) and silty clay loam, and silty clay loam and silty clay. The MC-LN model was able to accurately quantify the vertical changes of textures in the soil profiles. This study will aid in quantification of water and solute transport in soils with vertical heterogeneity of soil textural layers.
Helical flow of surface protein required for bacterial gliding motility
Authors: Nakane Daisuke , Sato Keiko , Wada Hirofumi , McBride Mark J. , Nakayama Koji
Published: June 2013

Cells of
Flavobacterium johnsoniae
and of many other members of the phylum Bacteroidetes exhibit rapid gliding motility over surfaces by a unique mechanism. These cells do not have flagella or pili; instead, they rely on a novel motility apparatus composed of Gld and Spr proteins. SprB, a 669-kDa cell-surface adhesin, is required for efficient gliding. SprB was visualized by electron microscopy as thin 150-nm-long filaments extending from the cell surface. Fluorescence microscopy revealed movement of SprB proteins toward the poles of the cell at ∼2 μm/s. The fluorescent signals appeared to migrate around the pole and continue at the same speed toward the opposite pole along an apparent left-handed helical closed loop. Movement of SprB, and of cells, was rapidly and reversibly blocked by the addition of carbonyl cyanide
m
-chlorophenylhydrazone, which dissipates the proton gradient across the cytoplasmic membrane. In a gliding cell, some of the SprB protein appeared to attach to the substratum. The cell body moved forward and rotated with respect to this point of attachment. Upon reaching the rear of the cell, the attached SprB often was released from the substratum, and apparently recirculated to the front of the cell along a helical path. The results suggest a model for
Flavobacterium
gliding, supported by mathematical analysis, in which adhesins such as SprB are propelled along a closed helical loop track, generating rotation and translation of the cell body.
Model for macroevolutionary dynamics
Authors: Maruvka Yosef E. , Shnerb Nadav M. , Kessler David A. , Ricklefs Robert E.
Published: June 2013

Significance

Genera are often viewed as artificial constructs of taxonomic practice. Here, we show that a stochastic model that includes three events with constant rates—species formation, extinction of species, and origination of new genera—can describe well the species-within-genus distributions for large taxa. Predictions from the model, including origination times of large taxa and origination rates of genera, match values obtained by other methods. Likewise, estimated extinction rates are close to speciation rates, which is consistent with the paleontological record. The model’s success emphasizes that, although taxonomic groupings are manmade, they nonetheless reflect natural evolutionary processes.
IL-22–producing neutrophils contribute to antimicrobial defense and restitution of colonic epithelial integrity during colitis
Authors: Zindl Carlene L. , Lai Jen-Feng , Lee Yun Kyung , Maynard Craig L. , Harbour Stacey N. , Ouyang Wenjun , Chaplin David D. , Weaver Casey T.
Published: June 2013

IL-22 plays an important role in mucosal epithelial cell homeostasis. Using a dextran sodium sulfate-induced mouse model of acute colitis, we observed an IL-23–dependent up-regulation of IL-22 in the middle and distal colon at the onset of epithelial cell damage. This heightened IL-22 correlated with an influx of innate immune cells, suggesting an important role in colonic epithelial protection. Freshly isolated colon-infiltrating neutrophils produced IL-22 contingent upon IL-23 signaling, and IL-22 production was augmented by TNF-α. Importantly, the depletion of neutrophils resulted in diminished IL-22 levels in the colon, and the transfer of IL-22–competent neutrophils to
Il22a
-deficient mice protected the colonic epithelium from dextran sodium sulfate-induced damage. In addition, IL-22–producing neutrophils targeted colonic epithelial cells to up-regulate the antimicrobial peptides, RegIIIβ and S100A8. This study establishes a role for neutrophils in providing IL-22–dependent mucosal epithelial support that contributes to the resolution of colitis.
FtsK actively segregates sister chromosomes in
Escherichia coli
Authors: Stouf Mathieu , Meile Jean-Christophe , Cornet François
Published: June 2013

Bacteria use the replication origin-to-terminus polarity of their circular chromosomes to control DNA transactions during the cell cycle. Segregation starts by active migration of the region of origin followed by progressive movement of the rest of the chromosomes. The last steps of segregation have been studied extensively in the case of dimeric sister chromosomes and when chromosome organization is impaired by mutations. In these special cases, the divisome-associated DNA translocase FtsK is required. FtsK pumps chromosomes toward the
dif
chromosome dimer resolution site using polarity of the FtsK-orienting polar sequence (KOPS) DNA motifs. Assays based on monitoring
dif
recombination have suggested that FtsK acts only in these special cases and does not act on monomeric chromosomes. Using a two-color system to visualize pairs of chromosome loci in living cells, we show that the spatial resolution of sister loci is accurately ordered from the point of origin to the
dif
site. Furthermore, ordered segregation in a region ∼200 kb long surrounding
dif
depended on the oriented translocation activity of FtsK but not on the formation of dimers or their resolution. FtsK-mediated segregation required the MatP protein, which delays segregation of the
dif
-surrounding region until cell division. We conclude that FtsK segregates the terminus region of sister chromosomes whether they are monomeric or dimeric and does so in an accurate and ordered manner. Our data are consistent with a model in which FtsK acts to release the MatP-mediated cohesion and/or interaction with the division apparatus of the terminus region in a KOPS-oriented manner.
Calling to the anima mundi: on restoring soul within organizations
Authors: Rozuel Cécile
Published: June 2013

Concerns about the loss of spirit, morale, and morality in modern organizations, apparent in the growing spirituality-at-work literature, suggest that the dominant business paradigm is unbalanced. Grounded in a patriarchal view of the world, it effectively negates the feminine and its
intrinsic connection with nature. Alchemists, as C.G. Jung discussed extensively in his works, understood the risk of living in an unbalanced world which neglects the soul of the earth and the soul of people. This paper explores the lost connection with the soul and discusses its ethical implications.
In particular, I argue that the anima mundi (the world soul) can restore balance and values in organizations if she is attended to respectfully and with care. This process involves an appreciation of the feminine in its practical and archetypal sense, and some extensive inner work,
in the spirit of alchemical imagination, to understand ourselves and our organizations better.
Do people really say it is “likely” when they believe it is only “possible”? Effect of politeness on risk communication
Authors: Juanchich Marie , Sirota Miroslav
Published: June 2013

Politeness theory posits that speakers can use verbal probabilities (e.g., there is a chance, it is likely) to hedge bad news. So far, only indirect evidence supports that claim: From the hearer's standpoint, verbal probabilities are interpreted either as plain likelihood-communication devices or as face-management devices, resulting in different risk perceptions. The present research aims to test more directly the postulate of politeness theory by focusing on the effects of speakers' intentions on risk communication. In three experiments, participants communicated a probability by choosing an expression from a list of verbal probabilities. Results consistently showed that polite speakers communicated a different risk magnitude than informative speakers. Further findings indicate that the effect of the speakers' intention depends on the valence of the uncertain outcome. The theoretical and applied implications of these findings are discussed.
An Outbreak ofPseudomonas aeruginosaRespiratory Tract Infections Associated with Intrinsically Contaminated Ultrasound Transmission Gel
Authors: Chittick Paul , Russo Victoria , Sims Matthew , Robinson-Dunn Barbara , Oleszkowicz Susan , Sawarynski Kara , Powell Kimberly , Makin Jacob , Darnell Elizabeth , Boura Judith A. , Boyanton Bobby , Band Jeffrey
Published: June 2013

We describe an outbreak ofPseudomonas aeruginosarespiratory tract infections related to intrinsically contaminated ultrasound gel used for intraoperative transesophageal echocardiograms in cardiovascular surgery patients. This investigation led to a product safety alert by the Food and Drug Administration and the development of guidelines for appropriate use of ultrasound gel.
Spatiotemporal dynamics of condensins I and II: evolutionary insights from the primitive red alga Cyanidioschyzon merolae
Authors: Fujiwara Takayuki , Tanaka Kan , Kuroiwa Tsuneyoshi , Hirano Tatsuya
Published: June 2013

Condensins are multisubunit complexes that play central roles in chromosome organization and segregation in eukaryotes. Many eukaryotic species have two different condensin complexes (condensins I and II), although some species, such as fungi, have condensin I only. Here we use the red alga Cyanidioschyzon merolae as a model organism because it represents the smallest and simplest organism that is predicted to possess both condensins I and II. We demonstrate that, despite the great evolutionary distance, spatiotemporal dynamics of condensins in C. merolae is strikingly similar to that observed in mammalian cells: condensin II is nuclear throughout the cell cycle, whereas condensin I appears on chromosomes only after the nuclear envelope partially dissolves at prometaphase. Unlike in mammalian cells, however, condensin II is confined to centromeres in metaphase, whereas condensin I distributes more broadly along arms. We firmly establish a targeted gene disruption technique in this organism and find, to our surprise, that condensin II is not essential for mitosis under laboratory growth conditions, although it plays a crucial role in facilitating sister centromere resolution in the presence of a microtubule drug. The results provide fundamental insights into the evolution of condensin-based chromosome architecture and dynamics.
A resonant family of dynamically cold small bodies in the near-Earth asteroid belt
Authors: de la Fuente Marcos C. , de la Fuente Marcos R.
Published: June 2013

Near-Earth objects (NEOs) moving in resonant, Earth-like orbits are potentially important. On the positive side, they are the ideal targets for robotic and human low-cost sample return missions and a much cheaper alternative to using the Moon as an astronomical observatory. On the negative side and even if small in size (2–50 m), they have an enhanced probability of colliding with the Earth causing local but still significant property damage and loss of life. Here, we show that the recently discovered asteroid 2013 BS45 is an Earth co-orbital, the sixth horseshoe librator to our planet. In contrast with other Earth's co-orbitals, its orbit is strikingly similar to that of the Earth yet at an absolute magnitude of 25.8, an artificial origin seems implausible. The study of the dynamics of 2013 BS45 coupled with the analysis of NEO data show that it is one of the largest and most stable members of a previously undiscussed dynamically cold group of small NEOs experiencing repeated trappings in the 1:1 commensurability with the Earth. This new resonant family is well constrained in orbital parameter space and it includes at least 10 other transient members: 2003 YN107, 2006 JY26, 2009 SH2 and 2012 FC71 among them. 2012 FC71 represents the best of both worlds as it is locked in a Kozai resonance and is unlikely to impact the Earth. These objects are not primordial and may have originated within the Venus–Earth–Mars region or in the main-belt, then transition to Amor-class asteroid before entering Earth's co-orbital region. Objects in this group could be responsible for the production of Earth's transient irregular natural satellites.
Impact of an accurate modelling of primordial chemistry in high-resolution studies
Authors: Bovino S. , Grassi T. , Latif M. A. , Schleicher D. R. G.
Published: June 2013

The formation of the first stars in the Universe is regulated by a sensitive interplay of chemistry and cooling with the dynamics of a self-gravitating system. As the outcome of the collapse and the final stellar masses depend sensitively on the thermal evolution, it is necessary to accurately model the thermal evolution in high-resolution simulations. As previous investigations raised doubts regarding the convergence of the temperature at high resolution, we investigate the role of the numerical method employed to model the chemistry and the thermodynamics. Here we compare the standard implementation in the adaptive-mesh refinement code enzo, employing a first-order backward differentiation formula (BDF), with the fifth-order accurate BDF solver dlsodes. While the standard implementation in enzo shows a strong dependence on the employed resolution, the results obtained with dlsodes are considerably more robust, both with respect to the chemistry and thermodynamics, but also for dynamical quantities such as density, total energy or the accretion rate. We conclude that an accurate modelling of the chemistry and thermodynamics is central for primordial star formation.
Impact of Puroindolines on Semisweet Biscuit Quality: A Fractionation–Reconstitution Approach
Authors: Pauly Anneleen , Pareyt Bram , Lambrecht Marlies A. , Fierens Ellen , Delcour Jan A.
Published: June 2013

Puroindoline (PIN) proteins are a factor determining wheat kernel endosperm texture. Biscuits are preferably made from flour from soft wheat (Triticum aestivum L.). Such wheat contains relatively high levels of wild‐type PINs, the impact of which on biscuit quality is unclear. We here studied the impact of PINs on biscuit texture using model flour samples reconstituted from starch and gluten fractions with varying PIN levels. These were obtained by fractionating flour from soft or durum wheat containing either wild‐type or no PINs, respectively. This approach allowed largely retaining the interaction between PINs and either starch or gluten, such as it exists in flour. High PIN levels enhanced air incorporation during dough preparation, increased dough (lateral) expansion, and yielded larger biscuits with higher porosity, which was mainly because of the larger pores. Biscuit fracture stress negatively correlated with PIN level. Porosity contributed to biscuit mechanical properties, but PINs also affected biscuit matrix strength, which in turn affected fracture stress. PINs seem to exert their softening effect when present above a threshold level, and then they have a stronger impact on biscuit fracture stress than the wheat endogenous lipids.
Bumetanide, an Inhibitor of Cation-chloride Cotransporter Isoform 1, Inhibits γ-Aminobutyric Acidergic Excitatory Actions and Enhances Sedative Actions of Midazolam in Neonatal Rats
Authors: Koyama Yukihide , Andoh Tomio , Kamiya Yoshinori , Morita Satoshi , Miyazaki Tomoyuki , Uchimoto Kazuhiro , Mihara Takahiro , Goto Takahisa
Published: June 2013

Background:

It has been shown that γ-aminobutyric acid exerts excitatory actions on the immature brain due to the increased expression of Na+–K+–2Cl− cotransporter isoform 1. The authors sought to clarify whether midazolam, a γ-aminobutyric acid–mimetic hypnotic agent, causes neuronal excitation that can be blocked by bumetanide, a selective inhibitor of Na+–K+–2Cl− cotransporter isoform 1. Furthermore, the authors examined whether bumetanide potentiates the sedative effects of midazolam in neonatal rats.

Methods:

The authors measured the effects of midazolam with or without bumetanide on the cytosolic Ca2+ concentration ([Ca]2+
i) in hippocampal slices (n = 3 in each condition) from rats at postnatal days 4, 7, and 28 (P4, P7, and P28) using fura-2 microfluorometry. Neuronal activity in the hippocampus and thalamus after intraperitoneal administration of midazolam with or without bumetanide was estimated by immunostaining of phosphorylated cyclic adenosine monophosphate–response element–binding protein (n = 12 in each condition). Furthermore, the authors assessed effects of bumetanide on the sedative effect of midazolam by measuring righting reflex latency (n = 6 in each condition).

Results:

Midazolam significantly increased [Ca]2+
i in the CA3 area at P4 and P7 but not at P28. Bumetanide inhibited midazolam-induced increase in [Ca]2+
i. Midazolam significantly up-regulated phosphorylated cyclic adenosine monophosphate–response element–binding protein expression in a bumetanide-sensitive manner in the hippocampus at P7 but not P28. Bumetanide enhanced the sedative effects of midazolam in P4 and P7 but not P28 rats.

Conclusion:

These results suggest that γ-aminobutyric acid A receptor–mediated excitation plays an important role in attenuated sedative effects of midazolam in immature rats.