bluuebunny/crossref_metadata_2025 huggingface dataset:
New numerical methods for the photoelastic technique with high accuracy
Authors: Almeida Magalhaes Cristina , Americo Almeida Magalhaes Pedro
Published: October 2012

The objective of this research is to find new equations for a novel phase-shifting method in digital photoelasticity. Some innovations are proposed. In terms of phase-shifting, only the analyzer is rotated, and the other equations are deduced by applying a new numerical technique instead of the usual algebraic techniques. This approach can be used to calculate equation of phase with a larger sequence of images. Each image represents a pattern and a measurement of the stresses present in the object. A reduction in the difference between the theoretical and experimental values of stresses was obtained by increasing the number of images in the equations for calculating phase. Every photographic image has errors and random noise, but the uncertainties due to these effects can be reduced with a larger number of observations.
Water assisted gate induced temporal surface charge distribution probed by electrostatic force microscopy
Authors: Pascal-Levy Y. , Shifman E. , Sivan I. , Kalifa I. , Pal-Chowdhury M. , Shtempluck O. , Razin A. , Kochetkov V. , Yaish Y. E.
Published: October 2012

In this paper, we present a quantitative method to measure charge density on dielectric layers using electrostatic force microscopy. As opposed to previous reports, our method, which is based on force curve measurements, does not require preliminary knowledge of the tip-sample capacitance and its derivatives. Using this approach, we have been able to quantify lateral and temporal SiO2 surface charge distribution and have unveiled a gate-induced charge redistribution mechanism which takes place in the vicinity of grounded electrodes. We argue that this mechanism constitutes a dominant factor in the hysteresis phenomenon, which is frequently observed in the transfer characteristics of nano-scale devices.
First-principles study of point defects in solar cell semiconductor CuInS2
Authors: Chen Hui , Wang Chong-Yu , Wang Jian-Tao , Hu Xiao-Ping , Zhou Shao-Xiong
Published: October 2012

The formation energies and transition levels of point defects VCu, VIn, VS, InCu, CuIn, and OS in CuInS2 are studied using the hybrid density functional theory. It is found that the Heyd-Scuseria-Ernzerhof method can accurately describe the electronic structure and gives a band gap of 1.40 eV, in good agreement with the experimental value. On the other hand, we conclude that p-type semiconductor CuInS2 can be obtained under sulfur-rich condition with a certain copper and indium content, while n-type semiconductor CuInS2 can be easily obtained under the copper-rich, indium-rich, sulfur-poor, and non-oxygen conditions. These results provide an excellent account for the modification of the structural and electronic properties of CuInS2.
The magnetic structure of an epitaxial BiMn0.5Fe0.5O3 thin film on SrTiO3 (001) studied with neutron diffraction
Authors: Cortie D. L. , Stampfl A. P. J. , Klose F. , Du Y. , Wang X. L. , Zhao H. Y. , Kimura H. , Cheng Z. X.
Published: October 2012

High-angle neutron diffraction was used to directly reveal the atomic-scale magnetic structure of a single-crystalline BiMn0.5Fe0.5O3 thin film deposited on a SrTiO3 (001) substrate. The BiMn0.5Fe0.5O3 phase exhibits distinctive magnetic properties that differentiate it from both parent compounds: BiFeO3 and BiMnO3. A transition to long-range G-type antiferromagnetism was observed below 120 K with a (121212) propagation vector. A weak ferromagnetic behavior was measured at low temperature by superconducting quantum interference device (SQUID) magnetometry. There is no indication of the spin cycloid, known for BiFeO3, in the BiMn0.5Fe0.5O3 thin film. The neutron diffraction suggests a random distribution of Mn and Fe over perovskite B sites.
Study of molecule variation in various grades of human nuclear cataracts by confocal micro-Raman spectroscopy
Authors: Zhuang Zhengfei , Zhu Meifang , Huang Yanyue , Liu Jie , Guo Zhouyi , Xiong Ke , Li Ning , Chen Sijin , Qiu Xuejun
Published: October 2012

Confocal micro-Raman spectroscopy is employed to characterize various grades of human cataracts. Results show that the intensity ratio of the tyrosine doublet (I855/I833) changes from 1:1.07 ± 0.03 to 1:1.17 ± 0.05 with the aggravation of cataracts, which indicates that there are more tyrosine residues bound to strong H acceptors instead of bounding to water. The decrease of relative intensity at 880 cm−1 band suggests that the “buried” tryptophan residues become “exposed” during the course of lens opacification. A three-dimensional principal component analysis is used to classify the Raman spectra of opacity tissues, which show a one-to-one correspondence with different grades of cataracts.
Spherical torus equilibria reconstructed by a two-fluid, low-collisionality model
Authors: Ishida Akio , Steinhauer Loren C.
Published: October 2012

The two-fluid, low-collisionality equilibrium model [Ishida et al., Phys. Plasmas 17, 122507 (2010)] was applied to reconstruct the high-performance National Spherical Torus eXperiment (NSTX) [Bell et al., Phys. Plasmas 17, 082507 (2010)]. Profiles of the electron and ion temperatures, the toroidal flow, the density, and the magnetic field pitch angle of the reconstructed equilibrium fit well the measured profiles of NSTX shot 132484 at 0.7 s. The reconstructed equilibrium shows that (1) the global two-fluid effect is fairly large; (2) the perpendicular flow of both species differs significantly from the ExB drift; (3) local gradient scale lengths can be smaller than the ion inertial length especially on the outboard side; (4) the electrostatic potential varies along a given magnetic flux by as much as several percent of the electron temperature in the core region.
Computational fluid dynamics and frequency-dependent finite-difference time-domain method coupling for the interaction between microwaves and plasma in rocket plumes
Authors: Kinefuchi K. , Funaki I. , Shimada T. , Abe T.
Published: October 2012

Under certain conditions during rocket flights, ionized exhaust plumes from solid rocket motors may interfere with radio frequency transmissions. To understand the relevant physical processes involved in this phenomenon and establish a prediction process for in-flight attenuation levels, we attempted to measure microwave attenuation caused by rocket exhaust plumes in a sea-level static firing test for a full-scale solid propellant rocket motor. The microwave attenuation level was calculated by a coupling simulation of the inviscid-frozen-flow computational fluid dynamics of an exhaust plume and detailed analysis of microwave transmissions by applying a frequency-dependent finite-difference time-domain method with the Drude dispersion model. The calculated microwave attenuation level agreed well with the experimental results, except in the case of interference downstream the Mach disk in the exhaust plume. It was concluded that the coupling estimation method based on the physics of the frozen plasma flow with Drude dispersion would be suitable for actual flight conditions, although the mixing and afterburning in the plume should be considered depending on the flow condition.
Open-air direct current plasma jet: Scaling up, uniformity, and cellular control
Authors: Wu S. , Wang Z. , Huang Q. , Lu X. , Ostrikov K.
Published: October 2012

Atmospheric-pressure plasma jets are commonly used in many fields from medicine to nanotechnology, yet the issue of scaling the discharges up to larger areas without compromising the plasma uniformity remains a major challenge. In this paper, we demonstrate a homogenous cold air plasma glow with a large cross-section generated by a direct current power supply. There is no risk of glow-to-arc transitions, and the plasma glow appears uniform regardless of the gap between the nozzle and the surface being processed. Detailed studies show that both the position of the quartz tube and the gas flow rate can be used to control the plasma properties. Further investigation indicates that the residual charges trapped on the inner surface of the quartz tube may be responsible for the generation of the air plasma plume with a large cross-section. The spatially resolved optical emission spectroscopy reveals that the air plasma plume is uniform as it propagates out of the nozzle. The remarkable improvement of the plasma uniformity is used to improve the bio-compatibility of a glass coverslip over a reasonably large area. This improvement is demonstrated by a much more uniform and effective attachment and proliferation of human embryonic kidney 293 (HEK 293) cells on the plasma-treated surface.
CdSe quantum dots-poly(3-hexylthiophene) nanocomposite sensors for selective chloroform vapor detection at room temperature
Authors: Mondal S. P. , Bera S. , Narender G. , Ray S. K.
Published: October 2012

Olive oil capped CdSe quantum dots (QDs) of average size ∼6 nm have been grown by a green chemical route synthesis for the fabrication of nanocomposite organic vapor sensing devices. A highly selective, room temperature chloroform vapor sensor has been fabricated using capped CdSe QDs and conducting polymer [poly(3-hexylthiophene)] nanocomposites. The nanocomposite sensor has been tested with the choloroform vapor of concentration varying from 100-1200 ppm at room temperature using different bias voltages. The recovery time of the sensor has been found to be improved on illumination with a monochromatic light of 600 nm, due to the photo-induced enhancement of charge transfer in nanocomposites.
Temperature-dependent dynamic magnetization of FeCoHf thin films fabricated by oblique deposition
Authors: Phuoc Nguyen N. , Chai Guozhi , Ong C. K.
Published: October 2012

Temperature-dependent dynamic magnetization of FeCoHf thin films grown by oblique deposition technique was investigated systematically through the measurement of permeability spectra in a temperature range from 300 K to 420 K. With the change of oblique angle from 27° to 45°, the resonance frequency is increased from 2.4 GHz to 3.8 GHz at 300 K. The thermal stability for the samples with high oblique angle is not as good as that of the ones with lower oblique angle. In addition, the variation of the effective Gilbert damping factor, frequency linewidth, and static and dynamic permeabilities with temperature for different oblique angles are presented and discussed in detail.
Enhanced field emission from large scale uniform monolayer graphene supported by well-aligned ZnO nanowire arrays
Authors: Yang Zhicheng , Zhao Qing , Ou Yongxi , Wang Wei , Li Heng , Yu Dapeng
Published: October 2012

Large scale, uniform single-layer graphene was transferred onto well-aligned ZnO nanowire arrays to produce high density nanoscale protrusions within graphene for efficient field emission. Polymethyl methacrylate (PMMA) was used as a supporting layer to provide a quasi-flat surface for graphene transfer. Highly efficient (maximum current density of ∼500 μA/cm2) and stable field emission with low turn-on fields (5.4 V/μm) was observed due to highly localized electric field, which is much better than those without using PMMA. F-N plot showed an unique up-bending feature of single-layer graphene. Our approach provides an efficient way to produce high quality single-layer graphene field emitters.
Spherical shock-ignition experiments with the 40 + 20-beam configuration on OMEGA
Authors: Theobald W. , Nora R. , Lafon M. , Casner A. , Ribeyre X. , Anderson K. S. , Betti R. , Delettrez J. A. , Frenje J. A. , Glebov V. Yu. , Gotchev O. V. , Hohenberger M. , Hu S. X. , Marshall F. J. , Meyerhofer D. D. , Sangster T. C. , Schurtz G. , Seka W. , Smalyuk V. A. , Stoeckl C. , Yaakobi B.
Published: October 2012

Spherical shock-ignition experiments on OMEGA used a novel beam configuration that separates low-intensity compression beams and high-intensity spike beams. Significant improvements in the performance of plastic-shell, D2 implosions were observed with repointed beams. The analysis of the coupling of the high-intensity spike beam energy into the imploding capsule indicates that absorbed hot-electron energy contributes to the coupling. The backscattering of laser energy was measured to reach up to 36% at single-beam intensities of ∼8 × 1015 W/cm2. Hard x-ray measurements revealed a relatively low hot-electron temperature of ∼30 keV independent of intensity and timing. At the highest intensity, stimulated Brillouin scattering occurs near and above the quarter-critical density and the two-plasmon-decay instability is suppressed.
Dissipative ion-cyclotron oscillitons in a form of solitons with chirp in Earth's low-altitude ionosphere
Authors: Kovaleva I. Kh.
Published: October 2012

In this paper, we consider theoretically nonlinear ion-cyclotron gradient-drift dissipative structures (oscillitons) in low ionospheric plasmas. Similar to Nonlinear Optics and Condensed Matter Physics, the Ginzburg-Landau equation for the envelope of electric wave fields is derived, and solutions for oscillitons in the form of solitons with chirp are examined. The whole dissipative structure constitutes a soliton with a moving charge-neutral density hump. Conditions for excitation and properties of the structures are considered.
Second generation bioethanol potential of Turkey
Authors: Isci Asli
Published: October 2012

Energy security and energy independency are vital components of economic stability and national security. The largest portion of the energy currently used in Turkey is derived from petroleum, 92% of which is imported. Besides depending on other countries’ non-renewable energy resources, petroleum consumption brings environmental problems as well. One fuel that has the potential to match the convenient features of petroleum is ethanol, produced from lignocellulosic biomass. In this study, the annual bioethanol potential of Turkey from major crop residues (wheat, barley, and rice straw; maize, cotton, and sunflower stalks) was estimated. Approximately, 21 × 106 tons of dry lignocellulosic biomass residue (excluding the amount to prevent soil erosion and animal feed) from these crops was available for conversion to bioethanol in 2011. Wheat and barley straw account for 54% and 22% of the total crop residue, respectively. The total lignocellulosic biomass could produce up to 6.10 Gl of bioethanol per year. The potential bioethanol production could replace 4.39 Gl of gasoline per year when bioethanol is used in E85 fuel for a midsize passenger vehicle. The estimations suggest that bioethanol production from only wheat and barley straw would be more than sufficient to replace total annual gasoline consumption in Turkey. Furthermore, Turkey can export approximately 1.8 Gl gasoline equivalent of bioethanol per year. These findings indicate that Turkey has a massive potential to be a zero-petroleum import country.
Limit on converted power in resonant electrostatic vibration energy harvesters
Authors: Blokhina E. , Galayko D. , Harte P. , Basset P. , Feely O.
Published: October 2012

Based on the formal analysis of a resonant electrostatic vibration energy harvester operating in constant-charge mode with a gap-closing transducer, we show that the system displays universal behaviour patterns. In this paper, we treat the harvester as a nonlinear forced oscillator and bound the area of control parameters where the system displays regular harmonic oscillations allowing the conditioning circuit to operate in the most effective mode. Before the system exhibits irregular behaviour, there exists a universal optimal value of normalised converted power regardless of the system design and control parameters.
Optimal hydrogenated amorphous silicon/silicon nitride bilayer passivation of n-type crystalline silicon using response surface methodology
Authors: Stepanov Dmitri S. , Kherani Nazir P.
Published: October 2012

This study reports the highest quality surface passivation achieved with hydrogenated amorphous silicon and amorphous silicon nitride (SiNx) bilayer stack deposited using plasma enhanced chemical vapour deposition on 1–2 Ωcm n-type crystalline silicon. The SiNx deposition conditions were investigated using response surface methodology (RSM). Optimized deposition parameters obtained from the RSM study yielded a low surface recombination velocity (SRV) of 3.5 cm/s. Interface defect and charge densities, inferred using the interface dangling bond recombination model, revealed a strong influence of charge on the SRV reduction. The model predicts a lower SRV of 1.5 cm/s for the bilayer passivation scheme.
Impact of growth temperature on InAs/GaInSb strained layer superlattices for very long wavelength infrared detection
Authors: Haugan H. J. , Brown G. J. , Elhamri S. , Mitchel W. C. , Mahalingam K. , Kim M. , Noe G. T. , Ogden N. E. , Kono J.
Published: October 2012

We explore the optimum growth space for a 47.0 Å InAs/21.5 Å Ga0.75In0.25Sb superlattices (SLs) designed for the maximum Auger suppression for a very long wavelength infrared gap. Our growth process produces a consistent gap of 50 ± 5 meV. However, SL quality is sensitive to the growth temperature (Tg). For the SLs grown at 390−470 °C, a photoresponse signal gradually increases as Tg increases from 400 to 440 °C. Outside this temperature window, the SL quality deteriorates very rapidly. All SLs were n-type with mobility of ∼10 000 V/cm2 and 300 K recombination lifetime of ∼70 ns for an optimized SL.
Reconfigurable liquid metal circuits by Laplace pressure shaping
Authors: Cumby Brad L. , Hayes Gerard J. , Dickey Michael D. , Justice Ryan S. , Tabor Christopher E. , Heikenfeld Jason C.
Published: October 2012

We report reconfigurable circuits formed by liquid metal shaping with <10 pounds per square inch (psi) Laplace and vacuum pressures. Laplace pressure drives liquid metals into microreplicated trenches, and upon release of vacuum, the liquid metal dewets into droplets that are compacted to 10–100× less area than when in the channel. Experimental validation includes measurements of actuation speeds exceeding 30 cm/s, simple erasable resistive networks, and switchable 4.5 GHz antennas. Such capability may be of value for next generation of simple electronic switches, tunable antennas, adaptive reflectors, and switchable metamaterials.
Causes of driving voltage rise in phosphorescent organic light emitting devices during prolonged electrical driving
Authors: Siboni Hossein Zamani , Aziz Hany
Published: October 2012

We studied the driving voltage stability of typical phosphorescent organic light emitting devices (PHOLEDs) based on 4,4′-bis(carbazol-9-yl)biphenyl and Tris(2-phenylpyridine)iridium(III) host:guest system. The results show that the gradual increase in voltage often observed with prolonged electrical driving is mainly governed by the accumulation of holes at the emission layer/hole blocking layer interface. Reducing the build-up of hole space charges in this region, for example, by means of eliminating guest molecules from the vicinity of the interface, leads to a significant improvement in the stability of PHOLED driving voltage.
Controllable aggregates of silver nanoparticle induced by methanol for surface-enhanced Raman scattering
Authors: Zhang Zhiliang , Wen Yongqiang
Published: October 2012

In this work, a series of highly sensitive surface-enhanced Raman scattering substrates have been achieved based on the controllable aggregation of silver nanoparticles. In such system, hexadecylamine-capped silver nanoparticles were ink-jet printed on glass substrates and subsequently dipped into methanol solution. An aggregation was induced due to preferential dissolution of hexadecylamine into methanol and partial removal of the protective layers on silver nanoparticle surfaces, which exhibited stable and controllable Raman enhancement effect. This strategy could be further extended to construct various chemical and biological functional sensors.
Role of surface charge, morphology, and adsorbed moieties on thermal conductivity enhancement of nanofluids
Authors: Anbumozhi Angayarkanni S. , Philip John
Published: October 2012

The role of surface charge, morphology, and adsorbed moieties on thermal conductivity is studied using soft micellar systems and alumina nanofluids of size varying from 2.5 to 30 nm. The thermal conductivity of soft systems of different sizes, surface charges, and morphologies is found to follow effective medium theory of poor thermal conductors. It is observed that the adsorption of surface active moieties on alumina nanoparticles does not lower the enhanced thermal conductivity of nanofluids but significantly enhances the stability and dispersibility of nanomaterials. Further, the cationic and non-ionic surfactants provide optimal thermal to rheological property enhancements.
Highly enhanced Raman scattering from coupled vertical silicon nanowire arrays
Authors: Khorasaninejad M. , Dhindsa N. , Walia J. , Patchett S. , Saini S. S.
Published: October 2012

Vertical silicon nanowire (SiNW) arrays were fabricated in square lattices with varying diameters, pitches, and lengths, in order to investigate the effects on Raman scattering enhancement. An increase in absolute intensity of the 520 cm−1 vibrational mode by a factor of 15 was achieved for 1.1 μm long SiNWs with diameter of 115 nm arranged 400 nm apart. An oscillatory behaviour in the Raman intensity was also observed with increasing diameter, which is a result of constructive and destructive interferences within the array. A maximum Raman enhancement per unit volume (REV) of 838 was achieved for 115 nm diameter SiNWs with a length of 1.1 μm. The experimental REV results were supported and modelled quantitatively using finite difference time domain simulations.
Quantum phase slips in superconducting Nb nanowire networks deposited on self-assembled Si templates
Authors: Cirillo C. , Trezza M. , Chiarella F. , Vecchione A. , Bondarenko V. P. , Prischepa S. L. , Attanasio C.
Published: October 2012

Robust porous silicon substrates were employed for generating interconnected networks of superconducting ultrathin Nb nanowires. Scanning electron microscopy analysis was performed to investigate the morphology of the samples, which constitute of polycrystalline single wires with grain size of about 10 nm. The samples exhibit nonzero resistance over a broad temperature range below the critical temperature, fingerprint of phase slippage processes. The transport data are satisfactory reproduced by models describing both thermal and quantum fluctuations of the superconducting order parameter in thin homogeneous superconducting wires.
Current dependence of electro-optical parameters in green and blue (AlIn)GaN laser diodes
Authors: Hager T. , Brüderl G. , Lermer T. , Tautz S. , Gomez-Iglesias A. , Müller J. , Avramescu A. , Eichler C. , Gerhard S. , Strauss U.
Published: October 2012

We present a detailed study of laser characteristics of blue and green R&D laser diodes grown on free standing GaN substrates with c-plane orientation under forward current condition. The slope efficiency of the blue emitting device exhibits a constant value over the entire operation range. In contrast to that, the green laser shows a decrease in slope efficiency with increasing current. A reduction of slope efficiency can be caused either by increasing internal losses or decreasing injection efficiency. A series of different mirror coatings is used to correlate the decreasing slope efficiency with a slight decrease of the injection efficiency as a function of current density. Furthermore, the reduction of the injection efficiency does not depend on the junction temperature. We could also verify that the internal losses are not temperature sensitive for blue and green laser diodes.
On optimization of sub-THz gyrotron parameters
Authors: Dumbrajs O. , Nusinovich G. S.
Published: October 2012

The theory is developed describing how the optimization of gyrotron parameters should be done taking into account two effects deteriorating the gyrotron efficiency: the spread in electron velocities and the spread in the guiding center radii. The paper starts from qualitative analysis of the problem. This simplified theory is used for making some estimates for a specific gyrotron design. The same design is then studied by using more accurate numerical methods. Results of the latter treatment agree with former qualitative predictions.
Investigation of the sheath formation in a dusty plasma containing energetic electrons and nano-size dust grains
Authors: Foroutan G. , Akhoundi A.
Published: October 2012

Numerical simulations of the stationary multi-fluid equations are used to study the structure of a dusty plasma sheath in the presence of a beam of energetic electrons. It is found that even a small number of energetic electrons can strongly modify the sheath parameters, specially the sheath thickness. Depending on the magnitude of the beam flux, two different regimes of sheath thickness can be recognized; At small beam fluxes, the sheath is in the regime of thin sheath and its thickness grows linearly with the beam flux. As the beam flux increases, at a certain beam energy or beam number density, the sheath demonstrates a sharp transition to the regime of thick sheath where the width is almost three times larger. The beam parameters corresponding to the transition between the two regimes depend on the parameters of the background plasma. The beam transition energy increases with the electron temperature and dust number density while decreases with the dust radius. On the other hand, the beam transition number density is a non-monotonic function of the background plasma number density. The localization of dust particles above the substrate is intensified by the increase in the beam number density.
Harnessing electromechanical membrane wrinkling for actuation
Authors: Conn Andrew T. , Rossiter Jonathan
Published: October 2012

Dielectric elastomers are soft electromechanical transducers that can exhibit unstable wrinkling behavior under large electric fields. This instability can be exploited by optimizing electrode boundaries to accentuate or attenuate localized wrinkling. An analytical model is presented, which demonstrates that the critical electric field to induce wrinkling can be lowered as the electrode geometry changes from convex to concave. This allows a single dielectric elastomer membrane to generate either biaxial or uniaxial extension in specific regions. A prototype 56 μm thick membrane actuator incorporates this principle to generate an in-plane rotational output, producing an actuation stroke of 15.7°.
Detection of ultrafast laser ablation using quantum cascade laser-based sensing
Authors: Mezzapesa F. P. , Spagnolo V. , Ancona A. , Scamarcio G.
Published: October 2012

The impact of quantum cascade lasers (QCLs) intrinsically high sensitivity to external optical feedback intended for sensing applications such as in-line ablation rate measurements is experimentally demonstrated. We developed a QCL-based sensor to assess the voltage modulation at the laser terminals induced by fast displacement of the ablation front during the process. This work shows that the detection range of our diagnostic system is only limited by the emission wavelength of the QCL probe source and the capability to measure ablation rates as high as 160 nm/pulse was reported. This sensing technique can be employed with the whole class of quantum cascade lasers, whose emission spans from mid-IR to THz spectral region, thus enabling the extension of its applications to ultra-fast laser ablation processes.
The impact of commonly used approximations on the computation of the Seebeck coefficient and mobility of polar semiconductors
Authors: Ramu Ashok T. , Bowers John E.
Published: October 2012

Seebeck coefficient modeling and measurement has important applications in direct thermal to electrical energy conversion and solid-state physics. The computations of the Seebeck coefficient and mobility of polar semiconductors in the literature often employ certain approximations, notably the relaxation time approximation (RTA) and the truncation of the Boltzmann transport equation. We study the accuracy of these approximations as a function of the effective mass, temperature, and carrier concentration using a recently developed technique for rigorous solution of the Boltzmann transport equation. We find that the approximations give rise to considerable error in the computed Seebeck coefficients of heavily doped semiconductors with a low effective mass, and that the RTA is entirely inapplicable for the accurate computation of the mobility of several important materials.
Patterned optical anisotropy in woven conjugated polymer systems
Authors: Müller C. , Garriga M. , Campoy-Quiles M.
Published: October 2012

Weaving of highly oriented conjugated polymer/polyethylene tapes is demonstrated to permit the generation of concealed patterns that can be detected under appropriate polarized light illumination. This is achieved by exploiting the fact that the amount of transmitted light varies with the superposition sequence of semi-transparent objects that feature a high degree of linear birefringence as well as linear dichroism. An analysis based on Müller calculus provides a theoretical description of the observed optical behavior.
Damage at hydrogenated amorphous/crystalline silicon interfaces by indium tin oxide overlayer sputtering
Authors: Demaurex Bénédicte , De Wolf Stefaan , Descoeudres Antoine , Charles Holman Zachary , Ballif Christophe
Published: October 2012

Damage of the hydrogenated amorphous/crystalline silicon interface passivation during transparent conductive oxide sputtering is reported. This occurs in the fabrication process of silicon heterojunction solar cells. We observe that this damage is at least partially caused by luminescence of the sputter plasma. Following low-temperature annealing, the electronic interface properties are recovered. However, the silicon-hydrogen configuration of the amorphous silicon film is permanently changed, as observed from infra-red absorbance spectra. In silicon heterojunction solar cells, although the as-deposited film's microstructure cannot be restored after sputtering, no significant losses are observed in their open-circuit voltage.
Dielectric strength, optical absorption, and deep ultraviolet detectors of hexagonal boron nitride epilayers
Authors: Li J. , Majety S. , Dahal R. , Zhao W. P. , Lin J. Y. , Jiang H. X.
Published: October 2012

Hexagonal boron nitride (hBN) epilayers have been synthesized by metal organic chemical vapor deposition and their dielectric strength, optical absorption, and potential as a deep ultraviolet (DUV) detector material have been studied. Based on the graphene optical absorption concept, the estimated band-edge absorption coefficient of hBN is about 7 × 105/cm, which is more than 3 times higher than the value for wurtzite AlN (∼2 × 105 /cm). The dielectric strength of hBN epilayers exceeds that of AlN and is greater than 4.4 MV/cm based on the measured result for an hBN epilayer released from the host sapphire substrate. The hBN epilayer based DUV detectors exhibit a sharp cut-off wavelength around 230 nm, which coincides with the band-edge photoluminescence emission peak and virtually no responses in the long wavelengths. Based on the present study, we have identified several advantageous features of hBN DUV photodetectors: (1) low long wavelength response or high DUV to visible rejection ratio; (2) requiring very thin active layers due to high optical absorption; (3) high dielectric strength and chemical inertness and resistance to oxidation and therefore suitable for applications in extreme conditions; (4) high prospects of achieving flexible devices; and (5) possible integration with graphene optoelectronics due to their similar structures and lattice constants.
Amplified spontaneous emission of Rhodamine 6G embedded in pure deoxyribonucleic acid
Authors: Rau Ileana , Szukalski Adam , Sznitko Lech , Miniewicz Andrzej , Bartkiewicz Stanislaw , Kajzar Francois , Sahraoui Bouchta , Mysliwiec Jaroslaw
Published: October 2012

Deoxyribonucleic acid (DNA) is commonly viewed as a genetic information carrier. However, now it is recognized as a nanomaterial, rather than as a biological material, in the research field of nanotechnology. Here, we show that using pure DNA, doped with rhodamine 6G, we are able to observe amplified spontaneous emission (ASE) phenomenon. Moderate ASE threshold, photodegradation, and reasonable gain coefficient observed in this natural host gives some perspectives for practical applications of this system in biophotonics. Obtained results open the way and will be leading to construction of truly bio-lasers using nature made luminophores, such as anthocyanins.
Temperature and pressure dependent Mott potentials and their influence on self-limiting oxide film growth
Authors: Cai Na , Zhou Guangwen , Müller Kathrin , Starr David E.
Published: October 2012

Classic Cabrera-Mott theory stipulates that the limited oxide-film growth results from electron tunneling from the metal through the oxide film to adsorbed oxygen. This leads to an electric field across the oxide film that assists ion migration for low-temperature oxide-film growth. Here, we show that the field-driven oxide-film growth can be manipulated via the temperature and pressure of oxidation. The magnitude of the self-generated electric field depends on the oxygen surface coverage that exhibits a Langmuir isotherm behavior with changes in temperature and oxygen pressure. These observations demonstrate the ability to tune an interfacial reaction via self-adaptation to its environment.
An optical leveling technique for parallel near-field photolithography system
Authors: Liu Zhuming , Chen Xinyong , Zhang Yuan , Weaver John , Roberts Clive J.
Published: October 2012

An optical leveling technique is reported for a compact parallel (multi-cantilever) scanning near-field photolithography (SNP) prototype. This instrument operates in liquid and was designed to overcome the challenge of low sample throughput of previous serial scanning SNPs. A combination of zone plate lens array, probe array, and standard atomic force microscope feedback technique are employed to deliver parallel probe operation in the current SNP. Compared to the commonly used two-end or multi-end “force feedback” alignment techniques, the optical levelling technique applied provides a simple solution to maintaining all levers in an array within the near-field region. As a proof-of-principle experiment, the operation of the prototype was demonstrated by producing nano-scale patterns in parallel using scanning near-field photolithography.
Correction to Euler's equations and elimination of the closure problem in turbulence
Authors: Zak Michail
Published: October 2012

It has been demonstrated that the Euler equations of inviscid fluid are incomplete: according to the principle of release of constraints, absence of shear stresses must be compensated by additional degrees of freedom, and that leads to a Reynolds-type multivalued velocity field. However, unlike the Reynolds equations, the enlarged Euler's (EE) model provides additional equations for fluctuations, and that eliminates the closure problem. Therefore the EE equations are applicable to fully developed turbulent motions where the physical viscosity is vanishingly small compare to the turbulent viscosity, as well as to superfluids and atomized fluids. Analysis of coupled mean/fluctuation EE equations shows that fluctuations stabilize the whole system generating elastic shear waves and increasing speed of sound. Those turbulent motions that originated from instability of underlying laminar motions can be described by the modified Euler's equation with the closure provided by the stabilization principle: driven by instability of laminar motion, fluctuations grow until the new state attains a neutral stability in the enlarged (multivalued) class of functions, and these fluctuations can be taken as boundary conditions for the EE model. The approach is illustrated by an example.
Temporal analysis of the diet of the central rock-rat
Authors: Edwards G. P.
Published: October 2012

The central rock-rat (Zyzomys pedunculatus) is an endangered endemic rodent that has undergone a dramatic range contraction over the past century. It is currently known from only a small area of the West MacDonnell Ranges near Alice Springs. A previous investigation into the species’ diet that analysed a small number of faecal samples concluded tentatively that it was a granivore. The present study aimed to establish the dietary patterns of Z. pedunculatus across a two-year period in central Australia during which rainfall fluctuated markedly. Diet was determined through the microscopic analysis of material in faecal pellets of Z. pedunculatus trapped at approximately three-month intervals at five sites at Ormiston Gorge. Seed was found to be the most important dietary item, comprising on average 57.0% of the diet across sample periods. Under dry conditions, the amount of seed material in the diet declined and the amount of stem material increased. Plant material from 15 genera was recorded in the diet, most notably Sida spp., Solanum spp. and Triodia brizoides. All of the plant genera identified in the diet to date are widespread and common in the range country of central Australia and most are considered fire tolerant. On the basis that the diet contains more than 50% seeds, Z. pedunculatus can be described as a granivore. However, the diet is broad and includes both seeds and vegetative material from a range of plant species.
Terrestrial mammals of the south-western Little Sandy Desert, Western Australia
Authors: Start A. N. , Burbidge A. A. , Kendrick P. G. , McKenzie N. L.
Published: October 2012

The mammal fauna of the south-western Little Sandy Desert was systematically surveyed during three visits to each of five sites at three locations representing the array of surfaces in the biogeomorphic landscape of the study area. A fourth, less systematic, expedition revisited one location and sampled two new ones. Nineteen extant, native species and seven exotic species were recorded. Fourteen extant species were below the Critical Weight Range (CWR), two (both large macropods) were above it and three (a monotreme, a rodent and a dasyurid) were within it. Another five CWR species may persist but were not recorded. An additional 19 species, all within the CWR, are thought to have occurred in the area but are now presumed extinct or locally extinct; we recorded evidence for the former presence of four of them. Surface type was an important determinant of habitat and spatially minor surfaces were disproportionately diverse but differed in their relevance to indigenous and exotic species respectively. Sandstone ranges had the richest indigenous faunas and six extant species were restricted to that habitat. Loam and clay surfaces had the richest exotic faunas.
Comparative growth and biomass allocation of two varieties of cat's claw creeper, Dolichandra unguis-cati (Bignoniaceae) in Australia
Authors: Taylor Dianne B. J. , Dhileepan Kunjithapatham
Published: October 2012

Introduced as an ornamental vine, cat’s claw creeper Dolichandra unguis-cati (syn. Macfadyena unguis-cati) has invaded coastal and subcoastal areas of subtropical eastern Australia. Two varieties have been indentified, one of which (‘short-pod’) is found throughout south-eastern Australia, while the other (‘long-pod’) appears to be restricted to several sites in south-eastern Queensland. We compared the growth and biomass allocation patterns of the two varieties in the field over a 22-month period to determine if a higher growth rate and/or more efficient allocation of biomass may contribute to this disparity in distribution. The long-pod variety produced greater aboveground and total biomass than the short-pod variety in both riparian and non-riparian zones. Belowground the two varieties produced a similar number of tubers and overall biomass, though the long-pod variety allocated a smaller portion of its carbon belowground. High growth rates and greater biomass allocation aboveground are characteristic of invasive species, allowing them to outcompete and crowd out existing vegetation. There was no significant site by variety interaction, an indication of consistency in variety performance across riparian and non-riparian sites. Results from our study suggest that differences in growth and biomass allocations are unlikely to have contributed to the disparity in distribution of the two varieties. Despite currently occupying a relatively small range, the long-pod variety may be a more adept invader than the short-pod variety, and could become more prevalent in the future.
Glycolytic pathway activity: effect on IVM and oxidative metabolism of bovine oocytes
Authors: Gutnisky Cynthia , Morado Sergio , Dalvit Gabriel C. , Thompson Jeremy G. , Cetica Pablo D.
Published: October 2012

The aim of the present study was to determine the effect of altering glycolytic pathway activity during bovine IVM on the meiotic maturation rate, oxidative activity, mitochondrial activity and the mitochondrial distribution within oocytes. Glycolytic activity was manipulated using two inhibitors (ATP, NaF) and a stimulator (AMP) of key enzymes of the pathway. Inhibition of glucose uptake, lactate production and meiotic maturation rates was observed when media were supplemented with ATP or NaF. The addition of AMP to the maturation medium had no effect on glucose uptake, lactate production or meiotic maturation. In the absence of gonadotrophin supplementation, AMP stimulated both glucose uptake and lactate production. However, AMP also decreased cytoplasmic maturation, as determined by early cleavage. During IVM, oocyte oxidative and mitochondrial activity was observed to increase at 15 and 22 h maturation. Inhibiting glycolysis with ATP or NaF led to a reduced oxidative and mitochondrial pattern compared with the respective control groups. Stimulation of the pathway with AMP increased oxidative and mitochondrial activity. A progressive mitochondrial migration to the central area was observed during maturation; oocytes treated with ATP, NaF or AMP showed limited migration. The present study reveals the effects of altering glycolytic pathway activity in cumulus–oocyte complexes, revealing the link between glycolysis of the cumulus–oocyte complex and the oxidative and mitochondrial activity of the oocyte.
The role of public libraries in social justice
Authors: Vincent John
Published: October 2012

John Vincent coordinates The Network, formed in May 1999 as a legacy of a project funded by the Library and Information Commission, Public Library Policy and Social Exclusion (see Muddiman, 2000). The Network’s mission is ‘to assist the cultural sector, including libraries, museums, archives and galleries, heritage and other organisations, to work towards social justice’.
Comparing a Problem-Solving Workshop to a Conflict Assessment Framework: Conflict Analysis versus Conflict Assessment in Practice
Authors: Fisher Ronald J.
Published: October 2012

The nexus between peacebuilding and development is widely acknowledged, and yet the two fields continue to operate differently in diagnosing destructive intergroup conflicts, as demonstrated by conflict analysis methods versus conflict assessment frameworks. This article juxtaposes conflict analysis, as illustrated by a problem- solving workshop on the Cyprus conflict, with a specialised conflict assessment workshop on an intergroup conflict in India. A comparative analysis based on participant observation in each workshop revealed basic similarities, but these were outweighed by important differences primarily related to differing assumptions about conflict causation (relationships versus structures). The implications for greater cross-fertilisation and the improvement of practice in both fields are identified.
Dissociative versus Associative Responses to Social Identity Threat: The Role of Consumer Self-Construal
Authors: White Katherine , Argo Jennifer J. , Sengupta Jaideep
Published: October 2012

The current research examines the conditions under which consumers demonstrate associative versus dissociative responses to identity-linked products as a consequence of a social identity threat. Across four studies, the authors test the notion that reactions to social identity threat may be moderated by self-construal by examining subcultural differences in ethnic background, priming self-construal, and investigating cross-national differences in cultural background. Those with more independent self-construals tend to avoid identity-linked products when that identity is threatened versus not threatened. Those with more interdependent self-construals, in contrast, demonstrate more positive preferences for identity-linked products when that aspect of social identity is threatened. These effects arise because, while independents are motivated to restore positive self-worth when a social identity is threatened, interdependents access a repertoire of social identities to fulfill belongingness needs when threatened.
The Exception Is the Rule: Underestimating and Overspending on Exceptional Expenses
Authors: Sussman Abigail B. , Alter Adam L.
Published: October 2012

Purchases fall along a continuum from ordinary (common or frequent) to exceptional (unusual or infrequent), with many of the largest expenses (e.g., electronics, celebrations) being the most exceptional. Across seven studies, we show that, while people are fairly adept at budgeting and predicting how much they will spend on ordinary items, they both underestimate their spending on exceptional purchases overall and overspend on each individual purchase. Based on the principles of mental accounting and choice bracketing, we show that this discrepancy arises in part because consumers categorize exceptional expenses too narrowly, construing each as a unique occurrence and consequently overspending across a series of discretely exceptional expenses. We conclude by proposing an intervention that diminishes this tendency by helping consumers consider their spending on exceptional items as part of a larger set of purchases.
Frustrated Fatshionistas: An Institutional Theory Perspective on Consumer Quests for Greater Choice in Mainstream Markets
Authors: Scaraboto Daiane , Fischer Eileen
Published: October 2012

Why and how do marginalized consumers mobilize to seek greater inclusion in and more choice from mainstream markets? We develop answers to these questions drawing on institutional theory and a qualitative investigation of Fatshionistas, plus-sized consumers who want more options from mainstream fashion marketers. Three triggers for mobilization are posited: development of a collective identity, identification of inspiring institutional entrepreneurs, and access to mobilizing institutional logics from adjacent fields. Several change strategies that reinforce institutional logics while unsettling specific institutionalized practices are identified. Our discussion highlights diverse market change dynamics that are likely when consumers are more versus less legitimate in the eyes of mainstream marketers and in instances where the changes consumers seek are more versus less consistent with prevailing institutions and logics.
Money Isn’t Everything, but It Helps If It Doesn’t Look Used: How the Physical Appearance of Money Influences Spending
Authors: Di Muro Fabrizio , Noseworthy Theodore J.
Published: October 2012

Despite evidence that currency denomination can influence spending, researchers have yet to examine whether the physical appearance of money can do the same. This is important because smaller denomination bills tend to suffer greater wear than larger denomination bills. Using real money in the context of real purchases, this article demonstrates that the physical appearance of money can override the influence of denomination. The reason being, people want to rid themselves of worn bills because they are disgusted by the contamination from others, whereas people put a premium on crisp currency because they take pride in owning bills that can be spent around others. This suggests that the physical appearance of money matters more than traditionally thought, and like most things in life, it too is inextricably linked to the social context. The results suggest that money may be less fungible than people think.