bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure of kaolinite and influence of stacking faults: Reconciling theory and experiment using inelastic neutron scattering analysis
Authors: White Claire E. , Kearley Gordon J. , Provis John L. , Riley Daniel P.
Published: May 2013

The structure of kaolinite at the atomic level, including the effect of stacking faults, is investigated using inelastic neutron scattering (INS) spectroscopy and density functional theory (DFT) calculations. The vibrational dynamics of the standard crystal structure of kaolinite, calculated using DFT (VASP) with normal mode analysis, gives good agreement with the experimental INS data except for distinct discrepancies, especially for the low frequency modes (200 – 400 cm−1). By generating several types of stacking faults (shifts in the a,b plane for one kaolinite layer relative to the adjacent layer), it is seen that these low frequency modes are affected, specifically through the emergence of longer hydrogen bonds (O–H⋯O) in one of the models corresponding to a stacking fault of −0.3151a − 0.3151b. The small residual disagreement between observed and calculated INS is assigned to quantum effects (which are not taken into account in the DFT calculations), in the form of translational tunneling of the proton in the hydrogen bonds, which lead to a softening of the low frequency modes. DFT-based molecular dynamics simulations show that anharmonicity does not play an important role in the structural dynamics of kaolinite.
Sensitive thermal transitions of nanoscale polymer samples using the bimetallic effect: Application to ultra-thin polythiophene
Authors: Ahumada O. , Pérez-Madrigal M. M. , Ramirez J. , Curcó D. , Esteves C. , Salvador-Matar A. , Luongo G. , Armelin E. , Puiggalí J. , Alemán C.
Published: May 2013

A sensitive nanocalorimetric technology based on microcantilever sensors is presented. The technology, which combines very short response times with very small sample consumption, uses the bimetallic effect to detect thermal transitions. Specifically, abrupt variations in the Young's modulus and the thermal expansion coefficient produced by temperature changes have been employed to detect thermodynamic transitions. The technology has been used to determine the glass transition of poly(3-thiophene methyl acetate), a soluble semiconducting polymer with different nanotechnological applications. The glass transition temperature determined using microcantilevers coated with ultra-thin films of mass = 10−13 g is 5.2 °C higher than that obtained using a conventional differential scanning calorimeter for bulk powder samples of mass = 5 × 10−3 g. Atomistic molecular dynamics simulations on models that represent the bulk powder and the ultra-thin films have been carried out to provide understanding and rationalization of this feature. Simulations indicate that the film-air interface plays a crucial role in films with very small thickness, affecting both the organization of the molecular chains and the response of the molecules against the temperature.
The ethyl radical in superfluid helium nanodroplets: Rovibrational spectroscopy and ab initio computations
Authors: Raston Paul L. , Agarwal Jay , Turney Justin M. , Schaefer Henry F. , Douberly Gary E.
Published: May 2013

The ethyl radical has been isolated and spectroscopically characterized in 4He nanodroplets. The band origins of the five CH stretch fundamentals are shifted by < 2 cm−1 from those reported for the gas phase species [S. Davis, D. Uy, and D. J. Nesbitt, J. Chem. Phys. 112, 1823 (2000)10.1063/1.480746; T. Häber, A. C. Blair, D. J. Nesbitt, and M. D. Schuder, J. Chem. Phys. 124, 054316 (2006)10.1063/1.2140740]. The symmetric CH2 stretching band (v1) is rotationally resolved, revealing nuclear spin statistical weights predicted by G12 permutation-inversion group theory. A permanent electric dipole moment of 0.28 (2) D is obtained via the Stark spectrum of the v1 band. The four other CH stretch fundamental bands are significantly broadened in He droplets and lack rotational fine structure. This broadening is attributed to symmetry dependent vibration-to-vibration relaxation facilitated by the He droplet environment. In addition to the five fundamentals, three a1′ overtone/combination bands are observed, and each of these have resolved rotational substructure. These are assigned to the 2v12, v4 + v6, and 2v6 bands through comparisons to anharmonic frequency computations at the CCSD(T)/cc-pVTZ level of theory.
KAg11(VO4)4 as a candidate p-type transparent conducting oxide
Authors: Im Jino , Trimarchi Giancarlo , Peng Haowei , Freeman Arthur J. , Cloet Veerle , Raw Adam , Poeppelmeier Kenneth R.
Published: May 2013

For a material to be a good p-type transparent conducting oxide (TCO), it must simultaneously satisfy several design principles regarding its bulk and defect phase thermochemistry, its optical absorption spectrum, and its electric transport properties. Recently, we predicted Ag3VO4 to be p-type but with low conductivity and an optical band gap not large enough for transparency. To improve on the transport and optical properties of Ag3VO4, we searched an extended material space including quaternary compounds based on Ag, V, O, and an additional atom for a new candidate p-type TCO. From this set of quaternary materials, we selected KAg11(VO4)4, a known oxide with a crystal structure related to that of Ag3VO4. Notably, one could expect a possible enhancement of the concentration of hole producing Ag-vacancy defects in KAg11(VO4)4 due to its different local geometries of Ag atoms (2- and 3-fold coordinated) with respect to the 4-fold coordinated Ag atoms in Ag3VO4. By performing first-principles calculations, we found that KAg11(VO4)4 is an intrinsic p-type conductor and can be synthesized under conditions similar to those predicted for the synthesis of Ag3VO4. However, we predict that the intrinsic hole content in KAg11(VO4)4 is similar to that in Ag3VO4 even though KAg11(VO4)4 contains 2- and 3-fold coordinated Ag, hole producing sites with a lower defect formation energy than the 4-fold coordinated one. Our calculation demonstrates that the advantage from lower coordination number of the Ag atom in KAg11(VO4)4 can be offset by the change in the range of Ag chemical potential in which synthesis is allowed due to the oxide phases that Ag forms with K and that energetically compete with KAg11(VO4)4.
Analytical solutions of the Schrödinger equation for a two-dimensional exciton in magnetic field of arbitrary strength
Authors: Hoang-Do Ngoc-Tram , Hoang Van-Hung , Le Van-Hoang
Published: May 2013

The Feranchuk-Komarov operator method is developed by combining with the Levi-Civita transformation in order to construct analytical solutions of the Schrödinger equation for a two-dimensional exciton in a uniform magnetic field of arbitrary strength. As a result, analytical expressions for the energy of the ground and excited states are obtained with a very high precision of up to four decimal places. Especially, the precision is uniformly stable for the whole range of the magnetic field. This advantage appears due to the consideration of the asymptotic behaviour of the wave-functions in strong magnetic field. The results could be used for various physical analyses and the method used here could also be applied to other atomic systems.
Measurement of ultra-low power oscillators using adaptive drift cancellation with applications to nano-magnetic spin torque oscillators
Authors: Tamaru S. , Ricketts D. S.
Published: May 2013

This work presents a technique for measuring ultra-low power oscillator signals using an adaptive drift cancellation method. We demonstrate this technique through spectrum measurements of a sub-pW nano-magnet spin torque oscillator (STO). We first present a detailed noise analysis of the standard STO characterization apparatus to estimate the background noise level, then compare these results to the noise level of three measurement configurations. The first and second share the standard configuration but use different spectrum analyzers (SA), an older model and a state-of-the-art model, respectively. The third is the technique proposed in this work using the same old SA as for the first. Our results show that the first and second configurations suffer from a large drift that requires ∼30 min to stabilize each time the SA changes the frequency band, even though the SA has been powered on for longer than 24 h. The third configuration introduced in this work, however, shows absolutely no drift as the SA changes frequency band, and nearly the same noise performance as with a state-of-the-art SA, thus providing a reliable method for measuring very low power signals for a wide variety of applications.
Electronic structure and thermoelectric properties of half-Heusler Zr0.5Hf0.5NiSn by first-principles calculations
Authors: Zou D. F. , Xie S. H. , Liu Y. Y. , Lin J. G. , Li J. Y.
Published: May 2013

The electronic structures of Zr0.5Hf0.5NiSn and the parent compounds ZrNiSn and HfNiSn are investigated by using first-principles calculations, and the thermoelectric properties are calculated on the base of the semi-classical Boltzmann transport theory and the empirical thermal conductivity model. The temperature dependence of thermoelectric transport properties of these three compounds is discussed and compared with experimental data, and good agreements are observed. To further optimize the thermoelectric performance of the Zr0.5Hf0.5NiSn compound, the chemical potential dependence of electrical transport properties at three different temperatures is investigated, and the maximum power factors and corresponding optimal p- or n-type doping levels are evaluated, suggesting that the compound has better thermoelectric performance when it is p-type doped.
Bi-layer Al2O3/ZnO atomic layer deposition for controllable conductive coatings on polypropylene nonwoven fiber mats
Authors: Sweet William J. , Jur Jesse S. , Parsons Gregory N.
Published: May 2013

Electrically conductive zinc oxide coatings are applied to polypropylene nonwoven fiber mats by atomic layer deposition (ALD) at 50–155 °C. A low temperature (50 °C) aluminum oxide ALD base layer on the polypropylene limits diffusion of diethyl zinc into the polypropylene, resulting in ZnO layers with properties similar to those on planar silicon. Effective conductivity of 63 S/cm is achieved for ZnO on Al2O3 coated polypropylene fibers, and the fibers remain conductive for months after coating. Without the Al2O3 precoating, the effective conductivity was much smaller, consistent with precursor diffusion into the polymer and sub-surface ZnO nucleation. Mechanical robustness tests showed that conductive samples bent around a 6 mm radius maintained up to 40% of the pre-bending conductivity. Linkages between electrical conductivity and mechanical performance will help inform materials choice for flexible and porous electronics including textile-based sensors and antennas.
Constructal paddle design with “fingers”
Authors: Cetkin E. , Lorente S. , Bejan A.
Published: May 2013

Here, we show how the performance of a paddle that pushes a fluid can be increased by making parallel slits through it. The slit spacing is varied to see its effect on the drag force and the maximum stress in the paddle. The effect of water speed and paddle dimensions is documented. Designs with one or more slits are investigated. The drag force is maximum when the slit spacing matches the boundary layer thickness of the flow through the slit. Furthermore, the drag force is greater when the slit spacing is nonuniform: larger in the central slits than in the peripheral slits. The paddle with slits of one size performs almost as well as the best design with nonuniform spacings. The paddle design with slits achieves the same drag force and maximum stress with less material compared with a paddle without slits.
Why twisting angles are diverse in graphene Moiré patterns?
Authors: Jiang Jin-Wu , Wang Bing-Shen , Rabczuk Timon
Published: May 2013

The interlayer energy of the twisting bilayer graphene is investigated by the molecular mechanics method using both the registry-dependent potential and the Lennard-Jones potential. Both potentials show that the interlayer energy is independent of the twisting angle θ, except in the two boundary regions θ≈0° or 60∘, where the interlayer energy is proportional to the square of the twisting arc length. The calculation results are successfully interpreted by a single atom model. An important information from our findings is that, from the energy point of view, there is no preference for the twisting angle in the experimental bilayer graphene samples, which actually explains the diverse twisting angles in the experiment.
Investigating the magnetic field effect on electron-hole pair in organic semiconductor devices
Authors: Qin W. , Gao K. , Yin S. , Xie S. J.
Published: May 2013

By constructing dynamic equations including electrons, holes and their pair densities, we calculate the magnetoconductance (MC) and the magnetoelectroluminescence (MEL) separately. It is indicated that MC and MEL may result from different response on the applied magnetic field. MC is from the scattering of polarons by magnetic field related triplet excitons, while MEL is mainly from magnetic field related conversion between singlet and triplet electron-hole pairs. Furthermore, we discuss the relation between MC and MEL. The theoretical calculations are well consistent with the experimental results.
Progressive structural and electronic properties of nano-structured carbon atomic chains
Authors: Usanmaz D. , Srivastava G. P.
Published: May 2013

Ab initio calculations, based on the planewave pseudopotential method and the density functional theory, have been reported on the changes in the electronic and structural properties of short carbon atomic chains held rigidly between hydrogenated thin armchair graphene nanoribbons (Na-AGNR) of dimer line numbers Na = 4 and 5. We have considered chains of several lengths (n = 4–9 atoms) and with different forms of attachment with the AGNRs. It is found that odd-numbered chains are metallic in nature, with chemical bonding more like ⋯ CCCC⋯ (as in cumulene). Even numbered chains show semiconductor structure when held between 4-AGNR and semi-metallic nature when held between 5-AGNR, in both cases characterized by chemical bonding more like ⋯ CCCCC⋯ (as in polyyne).
Enhanced temperature dependent junction magnetoresistance in La0.7Sr0.3MnO3/Zn(Fe, Al)O carrier induced dilute magnetic semiconductor junctions
Authors: Chattopadhyay S. , Panda J. , Nath T. K.
Published: May 2013

Metal-semiconductor type junction based on p-type La0.7Sr0.3MnO3 and n-type ZnO, Zn(Fe)O or Zn(Fe,Al)O with different Fe concentrations have been fabricated on (0001) sapphire substrate using pulsed laser deposition technique. While the metal-semiconductor type junction with La0.7Sr0.3MnO3 (LSMO) and ZnO or Zn(Fe)O show very good rectifying behavior, the heterojunction with La0.7Sr0.3MnO3 and Zn(Fe,Al)O fails to show such rectifying characteristics which most likely due to the much higher carrier concentration and thin depletion width. These metal-semiconductor type junctions show reasonably high temperature dependent junction magnetoresistive behavior. At 77 and 300 K all the junctions show negative junction magnetoresistance, whereas they show positive junction magnetoresistance at certain temperature range (150–280 K). The junction MR attains a peak with high positive value ∼76%, 38%, and 25% for LSMO/Zn(Fe,Al)O, LSMO/Zn(Fe)O, and LSMO/ZnO junctions, respectively, near 250 K, where La0.7Sr0.3MnO3 shows highest spin relaxation near 250 K. The junction magnetoresistive properties have been explained using the standard spin injection mechanism through the magnetic p-n junction. Junction magnetoresistance dies out with the increase of doping concentrations in all the three type of metal-semiconductor type junctions due to the less non equilibrium population of polarized electrons.
Photothermal formation of vortex flows by 1.55 μm light
Authors: Xu Rui , Xin Hongbao , Li Baojun
Published: May 2013

Fluid flows with four vortices were simultaneously formed on water surface based on photothermal effect induced by a laser beam of 1.55 μm wavelength. With the illumination of an optical power of 60 mW, the peak velocity of each vortex flow was reached to 1200 μm/s. Influence of optical power and attack angle on the vortex flows has been investigated. The mechanism of photothermal formation was analyzed with the assistance of a finite-element simulation.
Ferromagnetism, adatom effect, and edge reconstruction induced by Klein boundary in graphene nanoribbons
Authors: Bao Zhi-qiang , Shi Jun-jie , Zhang Min
Published: May 2013

The electronic structure and magnetic characteristics of Klein graphene nanoribbons (KGNRs), as observed by Suenaga and Koshino [K. Suenaga and M. Koshino, Nature 468, 1088 (2010)], are investigated using first-principles calculations. We find three new characteristics induced by the Klein boundary. First, the localized edge states in the KGNRs have a ferromagnetic coupling rather than the antiferromagnetic coupling of the zigzag graphene nanoribbons (ZGNRs). Lieb's theorem is no longer applicable in the KGNRs. Second, the marginal single carbon adatom of the ZGNRs can destroy the edge states nearby. The edge states can recover if the length of the zigzag chains is equal to or greater than five times that of the lattice constant. Finally, we show that the pentagon-heptagon edge can be induced from the Klein boundary.
Trap levels in the atomic layer deposition-ZnO/GaN heterojunction—Thermal admittance spectroscopy studies
Authors: Krajewski Tomasz A. , Stallinga Peter , Zielony Eunika , Goscinski Krzysztof , Kruszewski Piotr , Wachnicki Lukasz , Aschenbrenner Timo , Hommel Detlef , Guziewicz Elzbieta , Godlewski Marek
Published: May 2013

In this work, a n-ZnO/p-GaN heterojunction is analyzed using admittance spectroscopy techniques. Capacitance transient measurements performed at 10 kHz reveal four majority-carrier deep levels, the most important one located at approximately 0.57 eV below the ZnO conduction band (CB) edge with a density about two orders of magnitude below the doping level (NT = 4 × 1015 cm−3). The others, located at 0.20 eV, 0.65 eV, and 0.73 eV, are about three orders of magnitude below the doping level (NT = 4–9 × 1014 cm−3).
RFX-mod: A multi-configuration fusion facility for three-dimensional physics studies
Authors: Piovesan P. , Bonfiglio D. , Auriemma F. , Bonomo F. , Carraro L. , Cavazzana R. , De Masi G. , Fassina A. , Franz P. , Gobbin M. , Marrelli L. , Martin P. , Martines E. , Momo B. , Piron L. , Valisa M. , Veranda M. , Vianello N. , Zaniol B. , Agostini M. , Baruzzo M. , Bolzonella T. , Canton A. , Cappello S. , Chacón L. , Ciaccio G. , Escande D. F. , Innocente P. , Lorenzini R. , Paccagnella R. , Puiatti M. E. , Scarin P. , Soppelsa A. , Spizzo G. , Spolaore M. , Terranova D. , Zanca P. , Zanotto L. , Zuin M.
Published: May 2013

RFX-mod [Sonato et al., Fusion Eng. Des. 66, 161 (2003)] exploits its 192 active coils in both reversed-field pinch (RFP) and tokamak configurations with varying degrees of 3D shaping, providing also a test bed for validating stellarator codes and 3D nonlinear magnetohydrodynamic codes. This makes RFX-mod a unique and flexible facility for comparative studies on 3D shaping and control. The paper discusses how 3D fields allow access to RFP and tokamak advanced regimes. 3D fields are used to feedback control Single Helicity (SH) RFP equilibria with 1/7 helicity up to ∼2 MA. They also allow accessing SH regimes with higher density (Greenwald fraction up to 0.5), presently inaccessible in spontaneous SH regimes. Feedback on the 2/1 resistive-wall mode in RFX-mod tokamak plasmas allows for safe operation at q(a)<2, an almost unexplored promising regime. Forcing the 2/1 mode to saturate at finite but small level, a helical tokamak equilibrium with significant n = 1 modulation is produced and a new way to tailor sawteeth is found. The effects of different levels of 3D shaping on momentum transport in both RFP and tokamak helical states are discussed.
A micro seismometer based on molecular electronic transducer technology for planetary exploration
Authors: Huang Hai , Carande Bryce , Tang Rui , Oiler Jonathan , Zaitsev Dmitri , Agafonov Vadim , Yu Hongyu
Published: May 2013

This letter describes an implementation of micromachined seismometer based on molecular electronic transducer (MET) technology. As opposed to a solid inertial mass, MET seismometer senses the movement of liquid electrolyte relative to fixed electrodes. The employment of micro-electro-mechanical systems techniques reduces the internal size of the sensing cell to 1μm and improves the reproducibility of the device. For operating bias of 600 mV, a sensitivity of 809 V/(m/s2) was measured under acceleration of 400μg(g≡9.81m/s2) at 0.32 Hz. A −115 dB (relative to (m/s2)/Hz) noise level at 1 Hz was achieved. This work develops an alternative paradigm of seismic sensing device with small size, high sensitivity, low noise floor, high shock tolerance, and independence of installation angle, which is promising for next generation seismometers for planetary exploration.
Investigation of energy transfer and charge trapping in dye-doped organic light-emitting diodes by magneto-electroluminescence measurement
Authors: Peng Qiming , Gao Na , Li Weijun , Chen Ping , Li Feng , Ma Yuguang
Published: May 2013

We investigated the energy transfer and charge trapping (CT) in dye-doped organic light-emitting devices by using the magneto-electroluminescence as a tool. An intra-molecular charge-transfer fluorescent material N,N-diphenyl-4-(9-phenylnaphtho-[2,3-c][1,2,5]thiadiazol-4-yl)aniline was selected as the guest emitter. The tri-(8-hydroxyquinoline)-aluminum and 1,3-bis(9-carbazolyl)benzene were selected as the hosts. Our results demonstrate that as the energy difference between the HOMO (highest occupied molecular orbital)/LUMO (lowest unoccupied molecular orbital) of the host and the guest (ΔEHOMO/ΔELUMO) increases, the CT becomes more dominant, and the CT cannot be ignored even when the ΔEHOMO/ΔELUMO is small and the emission spectrum of the host overlaps the absorption spectrum of the guest well.
Reaching 10 ms single photon lifetimes for superconducting aluminum cavities
Authors: Reagor Matthew , Paik Hanhee , Catelani Gianluigi , Sun Luyan , Axline Christopher , Holland Eric , Pop Ioan M. , Masluk Nicholas A. , Brecht Teresa , Frunzio Luigi , Devoret Michel H. , Glazman Leonid , Schoelkopf Robert J.
Published: May 2013

Three-dimensional microwave cavities have recently been combined with superconducting qubits in the circuit quantum electrodynamics architecture. These cavities should have less sensitivity to dielectric and conductor losses at surfaces and interfaces, which currently limit the performance of planar resonators. We expect that significantly (>103) higher quality factors and longer lifetimes should be achievable for 3D structures. Motivated by this principle, we have reached internal quality factors greater than 0.5 × 109 and intrinsic lifetimes of 0.01 s for multiple aluminum superconducting cavity resonators at single photon energies and millikelvin temperatures. These improvements could enable long lived quantum memories with submicrosecond access times when strongly coupled to superconducting qubits.
Collisional effect on the Weibel instability with the bi-Maxwellian distribution function
Authors: Mahdavi M. , Khanzadeh H.
Published: May 2013

In this paper, the Coulomb collision effect of electron-ion is investigated based on the equilibrium bi-Maxwellian anisotropic distribution function in dense and unmagnetized plasma. An analytical expression is derived for the real frequency and the growth rate of the Weibel instability for two limiting cases |ξ=ω′k||θ|||≫1 and |ξ|≪1. In the limit |ξ|≪1, the quantity η that is due to a collisional term will appear in the growth and condition of the rate of the Weibel instability, which leads to a constraining condition of the growth rate. When η increases, the growth rate will increase and the wave instability will be distant from its own damping mode.
Laser ablated copper plasmas in liquid and gas ambient
Authors: Kumar Bhupesh , Thareja Raj K.
Published: May 2013

The dynamics of copper ablated plasma plumes generated using laser ablation of copper targets in both liquid (de-ionized water) and gas (air) ambients is reported. Using time and space resolved visible emission spectroscopy (450-650 nm), the plasma plumes parameters are investigated. The electron density (ne) determined using Stark broadening of the Cu I (3d104d1 2D3/2-3d104p1 2P3/2 at 521.8 nm) line is estimated and compared for both plasma plumes. The electron temperature (Te) was estimated using the relative line emission intensities of the neutral copper transitions. Field emission scanning electron microscopy and energy dispersive x-ray spectral analysis of the ablated copper surface indicated abundance of spherical nanoparticles in liquid while those in air are amalgamates of irregular shapes. The nanoparticles suspended in the confining liquid form aggregates and exhibit a surface plasmon resonance at ∼590 nm.
ZnO-SiO2 solar-blind photodetectors on flexible polyethersulfone substrate with organosilicon buffer layer
Authors: Lai Wei-Chih , Chen Jiun-Ting , Yang Ya-Yu
Published: May 2013

The ZnO-SiO2 nanocomposite solar-blind metal-semiconductor-metal photodetectors (PDs) on flexible polyethersulfone (PES) with an organosilicon (SiOx(CH3)) buffer layer improved the −10 V-biased responsivity of PDs illuminated wavelength of 240 nm from 0.75 A/W (without SiOx(CH3) buffer layer) to 3.86 A/W and the deep-ultraviolet (DUV)–visible rejection ratio of PDs from 8.10 × 104 (without SiOx(CH3) buffer layer) to 1.75 × 105. Moreover, the inserted SiOx(CH3) buffer layer would reduce the responsivity and DUV-visible rejection ratio of degradation of the severely bended ZnO-SiO2 nanocomposite PDs on PES.
Polyamorphism and origin of spatially heterogeneous dynamics in network-forming liquids under compression: Insight from visualization of molecular dynamics data
Authors: Hong N. V. , Lan M. T. , Nhan N. T. , Hung P. K.
Published: May 2013

Polyamorphism and dynamical heterogeneities in network-forming liquids (SiO2, GeO2, Al2O3) at 3200 K and in a wide pressure range are investigated by molecular dynamics simulation. Results show that their structure comprises three structural phases: TO4-, TO5-, and TO6-phases (T = Si, Ge, or Al). The size of structural phase regions significantly depends on compression. Besides, the mobility of atoms in different structural phases is different. For SiO2 and GeO2 systems, the TO5-phase forms mobile regions. For Al2O3 system, AlO6-phase forms mobile regions. The coexistence of TOx-phases (x = 4, 5, 6) in the network-forming liquids is origin of the spatially dynamical heterogeneity.
Intracellular temperature mapping with fluorescence-assisted photoacoustic-thermometry
Authors: Gao Liang , Zhang Chi , Li Chiye , Wang Lihong V.
Published: May 2013

Measuring intracellular temperature is critical to understanding many cellular functions but still remains challenging. Here, we present a technique–fluorescence-assisted photoacoustic thermometry (FAPT)–for intracellular temperature mapping applications. To demonstrate FAPT, we monitored the intracellular temperature distribution of HeLa cells with sub-degree (0.7 °C) temperature resolution and sub-micron (0.23 μm) spatial resolution at a sampling rate of 1 kHz. Compared to traditional fluorescence-based methods, FAPT features the unique capability of transforming a regular fluorescence probe into a concentration- and excitation-independent temperature sensor, bringing a large collection of commercially available generic fluorescent probes into the realm of intracellular temperature sensing.
Phonon and electron transport through Ge2Sb2Te5 films and interfaces bounded by metals
Authors: Lee Jaeho , Bozorg-Grayeli Elah , Kim SangBum , Asheghi Mehdi , Philip Wong H.-S. , Goodson Kenneth E.
Published: May 2013

While atomic vibrations dominate thermal conduction in the amorphous and face-centered cubic phases of Ge2Sb2Te5, electrons dominate in the hexagonal closed-packed (hcp) phase. Here we separate the electron and phonon contributions to the interface and volume thermal resistances for the three phases using time-domain thermoreflectance and electrical contact resistance measurements. Even when electrons dominate film-normal volume conduction (i.e., 70% for the hcp phase), their contribution to interface heat conduction is overwhelmed by phonons for high-quality interfaces with metallic TiN.
Understanding temperature dependence of threshold voltage in pentacene thin film transistors
Authors: Sun Qi-Jun , Gao Xu , Wang Sui-Dong
Published: May 2013

Threshold voltage in the pentacene-based organic thin film transistors is found to be linearly increased with decreasing measuring temperature, indicating that the threshold voltage is dominated by the deep hole trapping in an approximately energy-independent trap distribution. The slope of threshold voltage vs temperature is greatly reduced at 200–210 K when temperature is decreased, corresponding to a reduction in the deep trap density. H2O confined in pentacene is considered as one of the sources of the deep hole traps, and the slope change in the temperature dependence of threshold voltage is attributed to the phase transition of supercooled H2O.
Flexible field-effect transistor arrays with patterned solution-processed organic crystals
Authors: Li Yun , Liu Chuan , Wang Yu , Yang Yang , Wang Xinran , Shi Yi , Tsukagoshi Kazuhito
Published: May 2013

We demonstrate a fabrication process to develop field-effect transistor arrays based on patterned organic crystals as active semiconductor materials on flexible plastic substrates. Large plate-like organic crystals are produced by a direct spin-coating process on a substrate with patterned wettability. Resulting transistor arrays exhibit high device performance, indicating that the proposed method has great potential in flexible electronics.
Tall cell variant: An aggressive form of papillary thyroid carcinoma
Authors: Prendiville Stephen , Burman Kenneth D. , Ringel Matthew D. , Shmookler Barry M. , Deeb Ziad E. , Wolfe Katherine , Azumi Norio , Wartofsky Leonard , Sessions Roy B.
Published: May 2013

Twenty‐four cases of the tall cell variant (TCV), a subset of papillary thyroid carcinoma, were identified in a group of 624 patients with thyroid cancer. All pathology specimens were reviewed, and each patient's carcinoma was categorized according to characteristics on presentation, local recurrence, distant metastases, follow‐up, and tumor‐related mortality. The TCV group was compared with a historical control group (Mazzaferri and Jhiang: 1355 patients). The TCV group had a statistically higher percentage of stage 3 and 4 carcinoma, extrathyroidal invasion, and tumor size less than 1.5 cm than the control group. There was no statistical relationship between age greater than 50 years and stage in the TCV group. No relationship could be found between TCV histology and recurrence or mortality. These findings, combined with those of studies that link stage on presentation to poor outcomes, have led to our conclusion that TCV is an aggressive malignancy warranting appropriate treatment and close follow‐up.
Potential role of growth factors and extracellular matrix in wound healing after laryngotracheal reconstruction
Authors: Walner David L. , Heffelfinger Sue C. , Stern Yoram , Abrams Mark J. , Miller Mary Ann , Cotton Robin T.
Published: May 2013

Laryngotracheal reconstruction (LTR) has been used for more than 20 years to treat infants and children with subglottic stenosis. Results after pediatric LTR have been satisfactory; however, approximately 10% of children have recurrent airway narrowing after LTR. The purpose of our study was to determine whether a correlation existed between specific growth factors and extracellular matrix in patients with adequate wound healing capability as compared with patients with poor wound healing capability. Histologic sections from 27 patients who underwent LTR were cut, and immunohistochemical staining was performed for transforming growth factor‐β, platelet‐derived growth factor, fibronectin, tenascin, transforming growth factor‐α, and vascular endothelial growth factor. Results showed that patients with adequate wound healing capability had a positive correlation with vasculature fibronectin, vasculature tenascin, and stromal fibronectin. Patients with poor wound healing capability had a positive correlation with stromal vascular endothelial growth factor.
Radiofrequency volumetric reduction of the palate: An extended follow‐up study
Authors: Li Kasey K. , Powell Nelson B. , Riley Robert W. , Troell Robert J. , Guilleminault Christian
Published: May 2013

OBJECTIVE

The goal was to evaluate the effect of radiofrequency (RF) of the palate on speech, swallowing, taste, sleep, and snoring 12 to 18 months after treatment.

METHODS

Twenty‐two patients were evaluated by clinical examination, questionnaires, and visual analog scales. The patients with relapse of snoring were offered further RF treatment.

RESULTS

After a mean follow‐up of 14 months, no adverse effect was reported. Subjective snoring scores relapsed by 29% overall. Nine patients (41%) noted relapse of snoring from 2.1 ± 1.1 to 5.7 ± 2.7 (P < 0.001). Eight of the patients underwent further RF treatment with a reduction of snoring from 5.8 ± 2.9 to 3.3 ± 3.1 (P = 0.01).

CONCLUSION

The success of RF volumetric reduction of the palate diminishes with time, as with other surgical procedures of the palate. However, the minimal invasiveness of the RF provided a high patient acceptance for retreatment, and relapse of snoring can be improved.
Expression of matrix metalloproteinases and tissue inhibitor of metalloproteinases in laryngeal and pharyngeal squamous cell carcinoma: A quantitative analysis
Authors: Magary Steven P. , Ryan Matthew W. , Tarnuzzer R. W. , Kornberg Lori
Published: May 2013

Squamous cell carcinomas of the head and neck are known for their aggressive growth and propensity to metastasize. Invasion is facilitated by matrix metalloproteineases (MMPs). Tissue inhibitors of MMPs (TIMPs) negatively regulate MMP activity. MMP and TIMP expression in head and neck squamous cell carcinomas was determined by quantitative reverse transcriptase polymerase chain reaction (qRT‐PCR). qRT‐PCR allows measurement of several mRNAs from as little as 4 μg of total cellular RNA. We measured MMP‐1, MMP‐2, MMP‐9, and TIMP‐1 expression in 8 specimens of primary tumors and adjacent normal tissue. MMP‐1 was overexpressed in 6 of 8 tumors, and MMP‐9 was over‐expressed in 4 of 7 tumors. MMP‐2 was expressed in 3 of 8 tumors and 3 of 8 normal samples. TIMP‐1 was expressed in all specimens. This work demonstrates that qRT‐PCR can be used to examine expression of specific mRNAs in clinical specimens. Therefore this method provides another tool for the molecular analysis of tumors.
Effects of intracochlear factors on spiral ganglion cells and auditory brain stem response after long‐term electrical stimulation in deafened kittens
Authors: Araki Susumu , Kawano Atsushi , Lee Seldon H. , Shepherd Robert K. , Funasaka Sotaro , Clark Graeme M.
Published: May 2013

Using an animal model, we have studied the response of the auditory brain stem to cochlear implantation and the effect of intracochlear factors on this response. Neonatally, pharmacologically deafened cats (100 to more than 180 days old) were implanted with a 4‐electrode array in both cochleas. Then, the left cochlea of each cat was electrically stimulated for total periods of up to 1000 hours. After a terminal 14C‐2‐deoxyglucose (2DG) experiment, the fraction of the right inferior colliculus with a significant accumulation of 2DG label was calculated. Using 3‐dimensional computer‐aided reconstruction, we examined the cochleas of these animals for spiral ganglion cell (SGC) survival and intracochlear factors such as electrode positions, degeneration of the organ of Corti, and the degree of fibrosis of the scala tympani. The distribution of each parameter was calculated along the organ of Corti from the basal end. There was a positive correlation between SGC survival and the level of fibrosis in the scala tympani, and a negative correlation between SGC survival and the degree of organ of Corti degeneration. Finally, there was a negative correlation between the 2DG‐labeled inferior colliculus volume fraction and the degree of fibrosis, particularly in the 1‐mm region nearest the pair of electrodes, and presumably in the basal turn.
Treatment of benign paroxysmal positional vertigo: No need for postmaneuver restrictions
Authors: Nuti Daniele , Nati Catia , Passali Desiderio
Published: May 2013

The liberatory maneuver of Semont is an effective physical treatment for benign paroxysmal positional vertigo. It works because it causes otoconia to move out the posterior canal. The effectiveness of the maneuver is thought to be indicated by the appearance of a liberatory nystagmus. After the maneuver, patients are usually instructed to keep their heads erect for several days and not to lie on the pathologic side for about a week. Here we investigated the prognostic value of liberatory nystagmus and whether restrictions are necessary after treatment. Fifty‐six patients with posterior canal benign paroxysmal positional vertigo underwent the Semont maneuver and were checked after 20 minutes, 24 hours, and 1 week. The patients were told that they could sleep or move as they pleased, without any particular precautions. We found that liberatory nystagmus had a high prognostic value and that it was not necessary for patients to avoid certain positions or movements after treatment.
Acoustic analysis of the voice in phonatory fistuloplasty after total laryngectomy
Authors: Arias Mariano Rosique , RamÓN JosÉ Luis , Campos Matilde , Cervantes Juan JimÉNez
Published: May 2013

A comparative study of the voice with sustained phonation of the vowel /a/ was made in 3 groups of male patients: (1) 20 patients receiving total laryngectomy for epidermoid carcinoma of the larynx who had acquired good voice quality after a phonatory fistuloplasty with a Herrmann voice prosthesis; (2) 20 patients undergoing total laryngectomy for epidermoid carcinoma of the larynx who had learned esophageal speech; and (3) 20 subjects with normal voices. Statistical analysis yielded significant differences in fundamental voice frequency between the 3 groups, with the patients with phonatory prostheses revealing the closest to a normal voice. For other parameters used, such as jitter, shimmer, and harmonics/noise ratio, voice quality with a phonatory prosthesis was similar to that obtained with esophageal speech.
Postsurgical follow‐up of children with tympanostomy tubes: Results of the American Academy of Otolaryngology‐Head and Neck Surgery Pediatric Otolaryngology Committee National Survey
Authors: Derkay Craig S. , Carron Jeffrey D. , Wiatrak Brian J. , Choi Sukgi S. , Jones Jacqueline E.
Published: May 2013

Postsurgical follow‐up of children with tympanostomy tubes is becoming a contentious issue in this era of managed care. Primary care providers believe themselves to be capable of evaluating these children. Otolaryngologists, on the other hand, have more specialized equipment available to them (suction apparatus, otomicroscopes, audiology devices, etc) for treating suppurative infections and monitoring the tympanic membrane for structural changes. In addition, the otolaryngologist is placed in an uncomfortable legal and ethical position if access to the patient with a tube‐related complication is denied by the primary care provider. Attempts to develop an American Academy of Otolaryngology‐Head and Neck Surgery (AAO‐HNS) policy statement have been hampered by a lack of data on the incidence and severity of tube‐related complications and the role that otolaryngologists can play in reducing these sequelae. A survey designed by the AAO‐HNS Pediatric Otolaryngology Committee was distributed to 1000 board‐certified otolaryngologists and all members of the American Society of Pediatric Otolaryngologists and the American Academy of Pediatrics‐Otolaryngology Section regarding current practice patterns and practitioners' experiences with tympanostomy tube complications. Specific information regarding complications that could have been avoided with earlier otolaryngology referral was also obtained. The results of the survey and its implications for AAO‐HNS policy are presented.
Examining interactions between dingoes (wild dogs) and mesopredators: the need for caution when interpreting summary data from previously published work
Authors: Claridge Andrew W.
Published: May 2013

Australian Mammalogy has recently published papers by Fleming et al. (2012) and Johnson and Ritchie (2013). While not diametrically opposed, these papers variously question the notion that wild dogs can help suppress and/or regulate the activity and abundance of foxes and feral cats. They examine the evidence, or lack thereof, for support of the hypothesis. In doing so, it is clear from both papers that (1) hard experimental data to support or refute the hypothesis are mostly lacking, and (2) supporting or refuting the hypothesis is largely contingent on analyses and reanalyses of correlative evidence. Johnson and Ritchie (2013) inadvertently misinterpreted the results of a third study but they were not privy to additional information from that work that does not support their view. The main purpose of this paper is to, first, point out that information, and, second, to argue that until further experimental work is conducted, continuing to define the role and relative importance of wild dogs in Australian landscapes and applying that knowledge in a management setting will be difficult.
Germination of selected Australian native grass species, with potential for minesite rehabilitation
Authors: Farley Grus J. , Bellairs Sean M. , Adkins Stephen W.
Published: May 2013

Native grasses have become increasingly important in the post-mining landscape where land rehabilitators try to reconstruct vegetation communities similar to those present before land clearing. So as to include native grasses in these communities, there is a requirement to understand their germination biology, because in the past, many grasses have typically been hard to establish in the final community. The present study found that poor germination of 13 native grass species was due to (1) low percentage of seed fill, (2) low seed viability of filled seeds and/or (3) seed dormancy. Eight species had dormancy treatments investigated. Most were found to exhibit at least one form of dormancy that was either located in the hull structures immediately external to the caryopsis (i.e. the lemma, palea and glumes), within the seed coat (i.e. testa and pericarp, tissues that are found inside the hull, but external to the embryo and endosperm) and/or within the embryo. Seven of the grass species tested were found to have a dormancy mechanism present in two or more locations of their dispersal unit. Germination of the selected native grass species could be improved by (1) processing seeds to enrich the percentage of seeds that are filled, (2) testing viability to ensure a high proportion of the seeds are likely to germinate or (3) using methods to help overcome dormancy and promote germination.
Demographic transition among hunters: a temporal analysis of hunter recruitment dedication and motives in Denmark
Authors: Hansen Hans Peter , Peterson M. Nils , Jensen Charlotte
Published: May 2013

Context
In many countries, hunting has emerged as a major source of funding for wildlife conservation and research or habitat acquisition. In some countries, recent declines in recruitment of hunters have generated concerns about the consequences of the rapid demographic change within society in general, and among hunters in particular. Gaining a better understanding of how these demographic changes influence dedication to and motivation for hunting has therefore become an important task.

Aims
Our aims included documenting the demographic transition among Danish hunters, and identifying correlates of hunter recruitment age, motivations and dedication.

Methods
We addressed these aims using a national survey of Danish hunters in 2000 (n = 1186) and 2006 (n = 701). Survey data were analysed using multiple regression models.

Key results
Whereas recruitment numbers remained stable, the average age of recruitment for hunters increased from 21 to 34 between 1984 and 2006, and the percentage of new hunters younger than 20 declined from 63% to 19% during the same period. Respondents who hunted to experience nature were recruited at older ages than other hunters. Recruitment age was negatively related to number of days hunting per year and relative importance placed on hunting as a recreational activity, and positively related to being recruited by friends, female gender, being married, and having an urban childhood.

Conclusions
The global demographic transition towards an older and more urban populace may drive a change in hunter demographics rather than a decline of hunting.

Implications
The present study suggests that hunting can persist in the face of rapid demographic change. However, the study also indicates several important structural barriers for new hunters, favouring those hunters being economically most well off and leading to a decline in hunting dedication. To meet these challenges, the study suggests that modifications will be needed in hunter education programs and hunter recruitment campaigns, so as to maintain hunting as a significant positive factor within wildlife conservation.
Sequestration of a highly reactive intermediate in an evolving pathway for degradation of pentachlorophenol
Authors: Yadid Itamar , Rudolph Johannes , Hlouchova Klara , Copley Shelley D.
Published: May 2013

Significance

Microbes in contaminated environments often evolve new metabolic pathways for detoxification or degradation of pollutants. In some cases, intermediates in newly evolving pathways are more toxic than the initial compound. The initial step in the degradation of pentachlorophenol by
Sphingobium chlorophenolicum
generates a particularly toxic intermediate, tetrachlorobenzoquinone (TCBQ). This paper describes how the bacterium is protected from the toxic effects of TCBQ. In the presence of tetrachlorobenzoquinone reductase, TCBQ produced by pentachlorophenol hydroxylase is sequestered until it is reduced to the less toxic tetrachlorohydroquinone.
Arid5a controls IL-6 mRNA stability, which contributes to elevation of IL-6 level in vivo
Authors: Masuda Kazuya , Ripley Barry , Nishimura Riko , Mino Takashi , Takeuchi Osamu , Shioi Go , Kiyonari Hiroshi , Kishimoto Tadamitsu
Published: May 2013

Posttranscriptional regulation of IL-6 has been largely uncharacterized, with the exception of the ribonuclease Regnase-1, which prevents autoimmunity by destabilizing IL-6 mRNA. Here, we identified AT-rich interactive domain-containing protein 5A (Arid5a) as a unique RNA binding protein, which stabilizes IL-6 but not TNF-α mRNA through binding to the 3′ untranslated region of IL-6 mRNA. Arid5a was enhanced in macrophages in response to LPS, IL-1β, and IL-6. Arid5a deficiency inhibited elevation of IL-6 serum level in LPS-treated mice and suppressed IL-6 levels and the development of TH17 cells in experimental autoimmune encephalomyelitis. Importantly, Arid5a inhibited the destabilizing effect of Regnase-1 on IL-6 mRNA. These results indicate that Arid5a plays an important role in promotion of inflammatory processes and autoimmune diseases.