bluuebunny/crossref_metadata_2025 huggingface dataset:
Lignin fate and characterization during ionic liquid biomass pretreatment for renewable chemicals and fuels production
Authors: Sathitsuksanoh Noppadon , Holtman Kevin M. , Yelle Daniel J. , Morgan Trevor , Stavila Vitalie , Pelton Jeffrey , Blanch Harvey , Simmons Blake A. , George Anthe
Published: November 2013

The fate of lignin from wheat straw, Miscanthus, and Loblolly pine after pretreatment by a non-toxic and recyclable ionic liquid (IL), [C2mim][OAc], followed by enzymatic hydrolysis was investigated.
Tuning “thiol-ene” reactions toward controlled symmetry breaking in polyhedral oligomeric silsesquioxanes
Authors: Li Yiwen , Guo Kai , Su Hao , Li Xiaopeng , Feng Xueyan , Wang Zhao , Zhang Wei , Zhu Sunsheng , Wesdemiotis Chrys , Cheng Stephen Z. D. , Zhang Wen-Bin
Published: November 2013

A facile method toward polyhedral oligomeric silsesquioxane-based nano-building blocks with controlled symmetry breaking was reported by using thiol-ene chemistry.
A NiAl layered double hydroxide@carbon nanoparticles hybrid electrode for high-performance asymmetric supercapacitors
Authors: Liu Xiaoxi , Wang Chong , Dou Yibo , Zhou Awu , Pan Ting , Han Jingbin , Wei Min
Published: November 2013

A NiAl layered double hydroxide (LDH)@carbon nanoparticles (CNPs) hybrid electrode was fabricated via a facile and cost-effective approach and displays excellent pseudocapacitive behavior.
Fabrication of highly transparent and conducting PEDOT:PSS films using a formic acid treatment
Authors: McCarthy Joseph E. , Hanley Cormac A. , Brennan Lorcan J. , Lambertini Vito G. , Gun'ko Yurii K.
Published: November 2013

The improvement in the conductive properties of thin nanoscale films of the polymer PEDOT:PSS was achieved by spraying and post-treatment of the films using methanol and formic acid that resulted in sheet resistance values in the range of 3–4 orders of magnitude higher than for the untreated films.
Progress of a room temperature electron cyclotron resonance ion source using evaporative cooling technology at Institute of Modern Physics
Authors: Lu W. , Xiong B. , Zhang X. Z. , Sun L. T. , Feng Y. C. , Ma B. H. , Guo S. Q. , Cao R. , Ruan L. , Zhao H. W.
Published: November 2013

A new room temperature ECR ion source, Lanzhou Electron Cyclotron Resonance ion source No. 4 (LECR4, previously named DRAGON), is under intense construction at Institute of Modern Physics. LECR4 is designed to operate with 18 GHz microwave frequency. The maximum axial magnetic fields are 2.3 T at injection and 1.3 T at extraction, and the radial field at the plasma chamber wall of 76 mm inner diameter is 1.0–1.2 T. One of the unique features for LECR4 is that its axial solenoids are winded with solid square copper wires which are immersed in a kind of special evaporative cooling medium for cooling purpose. Till now, a prototype of the cooling system has been successfully constructed and tested, which has demonstrated that the cooling efficiency of the designed system could meet the requirements of LECR4 under the routine operation conditions. All the main components of the ion source have been completed. Assembly and commissioning is ongoing. The latest developments and test results will be presented in this paper.
The role of deposited layers in the nonlinear constitutive behavior of Si nanowires
Authors: Yashinski M. S. , Muhlstein C. L.
Published: November 2013

The experimentally measured elastic moduli and yield strengths of nanowires and nanofilaments vary widely in the literature and are often beyond the theoretical limits of the particular material. In this work, Si nanowires with very low defect densities were loaded in uniaxial tension to establish the origins of their apparently nonlinear constitutive behavior. The diameters of the nanowires ranged from 230 to 460 nm and the growth directions were primarily [112] with the exception of a [111] oriented nanowire. The resulting fracture strengths of the nanowires ranged from 3.88 to 10.1 GPa. The nonlinear constitutive behavior was accompanied by fracture surfaces with features that were not commonly observed in Si. A nonlinear continuum elasticity model and electron microscopy established that reports of unusual deformation behavior and fracture surface morphologies are a direct byproduct of the electron and ion beam deposited adhesives (Pt-based in this work) used to affix specimens in place for testing.
Spectral singularity in confined ${\cal {PT}}$PT symmetric optical potential
Authors: Sinha Anjana , Roychoudhury R.
Published: November 2013

We present an analytical study for the scattering amplitudes (Reflection |R| and Transmission |T|), of the periodic ${\cal {PT}}$PT symmetric optical potential $V(x) = \displaystyle W_0 \left( \cos ^2 x + i V_0 \sin 2x \right)$V(x)=W0cos2x+iV0sin2x confined within the region 0 ⩽ x ⩽ L, embedded in a homogeneous medium having uniform potential W0. The confining length L is considered to be some integral multiple of the period π. We give some new and interesting results. Scattering is observed to be normal (|T|2 ⩽ 1, |R|2 ⩽ 1) for V0 ⩽ 0.5, when the above potential can be mapped to a Hermitian potential by a similarity transformation. Beyond this point (V0 > 0.5) scattering is found to be anomalous (|T|2, |R|2 not necessarily ⩽1). Additionally, in this parameter regime of V0, one observes infinite number of spectral singularities ESS at different values of V0. Furthermore, for L = 2nπ, the transition point V0 = 0.5 shows unidirectional invisibility with zero reflection when the beam is incident from the absorptive side (Im[V(x)] < 0) but with finite reflection when the beam is incident from the emissive side (Im[V(x)] > 0), transmission being identically unity in both cases. Finally, the scattering coefficients |R|2 and |T|2 always obey the generalized unitarity relation : $||T|^2 - 1| = \sqrt{|R_R|^2 |R_L|^2}$‖T|2−1|=|RR|2|RL|2, where subscripts R and L stand for right and left incidence, respectively.
Formation of non-substitutional β-Sn defects in Ge1−xSnx alloys
Authors: Fuhr J. D. , Ventura C. I. , Barrio R. A.
Published: November 2013

Although group IV semiconductor alloys are expected to form substitutionally, in Ge1−xSnx this is true only for low concentrations (x < 0.13). The use of these alloys as a narrow gap semiconductor depends on the ability to produce samples with the high quality required for optoelectronic device applications. In a previous paper, we proposed the existence of a non-substitutional complex defect (β-Sn), consisting of a single Sn atom in the center of a Ge divacancy, which may account for the segregation of Sn at large x. Afterwards, the existence of this defect was confirmed experimentally. In this paper we study the local environment and the interactions of the substitutional defect (α-Sn), the vacancy in Ge, and the β-Sn defect by performing extensive numerical ab initio calculations. Our results confirm that a β-Sn defect can be formed by natural diffusion of a vacancy around the substitutional α-Sn defect, since the energy barrier for the process is very small.
Quantum-ring spin interference device tuned by quantum point contacts
Authors: Diago-Cisneros Leo , Mireles Francisco
Published: November 2013

We introduce a spin-interference device that comprises a quantum ring (QR) with three embedded quantum point contacts (QPCs) and study theoretically its spin transport properties in the presence of Rashba spin-orbit interaction. Two of the QPCs conform the lead-to-ring junctions while a third one is placed symmetrically in the upper arm of the QR. Using an appropriate scattering model for the QPCs and the S-matrix scattering approach, we analyze the role of the QPCs on the Aharonov-Bohm (AB) and Aharonov-Casher (AC) conductance oscillations of the QR-device. Exact formulas are obtained for the spin-resolved conductances of the QR-device as a function of the confinement of the QPCs and the AB/AC phases. Conditions for the appearance of resonances and anti-resonances in the spin-conductance are derived and discussed. We predict very distinctive variations of the QR-conductance oscillations not seen in previous QR proposals. In particular, we find that the interference pattern in the QR can be manipulated to a large extend by varying electrically the lead-to-ring topological parameters. The latter can be used to modulate the AB and AC phases by applying gate voltage only. We have shown also that the conductance oscillations exhibits a crossover to well-defined resonances as the lateral QPC confinement strength is increased, mapping the eigenenergies of the QR. In addition, unique features of the conductance arise by varying the aperture of the upper-arm QPC and the Rashba spin-orbit coupling. Our results may be of relevance for promising spin-orbitronics devices based on quantum interference mechanisms.
Reversible diffusion-influenced reactions of an isolated pair on some two dimensional surfaces
Authors: Prüstel Thorsten , Tachiya M.
Published: November 2013

We investigate reversible diffusion-influenced reactions of an isolated pair in two dimensions. To this end, we employ convolution relations that permit deriving the survival probability of the reversible reaction directly in terms of the survival probability of the irreversible reaction. Furthermore, we make use of the mean reaction time approximation to write the irreversible survival probability in restricted spaces as a single exponential. In this way, we obtain exact and approximative expressions in the time domain for the reversible survival probability for three different two dimensional spatial domains: The infinite plane, the annular domain, and the surface of a sphere. Our obtained results should prove useful in the context of membrane-bound reversible diffusion-influenced reactions in cell biology.
Coupled continuum and molecular model of flow through fibrous filter
Authors: Zhao Shunliu , Povitsky Alex
Published: November 2013

A coupled approach combining the continuum boundary singularity method (BSM) and the molecular direct simulation Monte Carlo (DSMC) is developed and validated using Taylor-Couette flow and the flow about a single fiber confined between two parallel walls. In the proposed approach, the DSMC is applied to an annular region enclosing the fiber and the BSM is employed in the entire flow domain. The parameters used in the DSMC and the coupling procedure, such as the number of simulated particles, the cell size, and the size of the coupling zone are determined by inspecting the accuracy of pressure drop obtained for the range of Knudsen numbers between zero and unity. The developed approach is used to study flowfield of fibrous filtration flows. It is observed that in the partial-slip flow regime, Kn ⩽ 0.25, the results obtained by the proposed coupled BSM-DSMC method match the solution by BSM combined with the heuristic partial-slip boundary conditions. For transition molecular-to-continuum Knudsen numbers, 0.25 < Kn ⩽ 1, the difference in pressure drop and velocity between these two approaches is significant. This difference increases with the Knudsen number that confirms the usefulness of coupled continuum and molecular methods in numerical modeling of transition low Reynolds number flows in fibrous filters.
Fluctuation of an ion beam extracted from an AC filament driven Bernas-type ion source
Authors: Miyamoto N. , Okajima Y. , Wada M.
Published: November 2013

Argon ion beam fluctuation from an AC filament driven Bernas-type ion source is observed. The ion beam was measured by an 8 measurement elements beam profile monitor. The amplitude of the beam current fluctuation stayed in the same level from 100 Hz to 1 kHz of the filament heating frequency. The beam current fluctuation frequency measured by the beam profile monitor was equal to the frequency of the AC filament operation. The fluctuation amplitudes of the beam current by AC operation were less than 7% and were in the same level of the DC operation.
Chemical reaction versus vibrational quenching in low energy collisions of vibrationally excited OH with O
Authors: Pradhan G. B. , Juanes-Marcos J. C. , Balakrishnan N. , Kendrick Brian K.
Published: November 2013

Quantum scattering calculations are reported for state-to-state vibrational relaxation and reactive scattering in O + OH(v = 2 − 3, j = 0) collisions on the electronically adiabatic ground state 2A′′ potential energy surface of the HO2 molecule. The time-independent Schrödinger equation in hyperspherical coordinates is solved to determine energy dependent probabilities and cross sections over collision energies ranging from ultracold to 0.35 eV and for total angular momentum quantum number J = 0. A J-shifting approximation is then used to compute initial state selected reactive rate coefficients in the temperature range T = 1 − 400 K. Results are found to be in reasonable agreement with available quasiclassical trajectory calculations. Results indicate that rate coefficients for O2 formation increase with increasing the OH vibrational level except at low and ultralow temperatures where OH(v = 0) exhibits a slightly different trend. It is found that vibrational relaxation of OH in v = 2 and v = 3 vibrational levels is dominated by a multi-quantum process.
Effect of an external electric field on the diffusion-influenced geminate reversible reaction of a neutral particle and a charged particle in three dimensions. III. Ground-state ABCD reaction
Authors: Reigh Shang Yik
Published: November 2013

In the presence of an external electric field, the ground-state \documentclass[12pt]{minimal}\begin{document}$A+B^q \rightleftharpoons C^q + D$\end{document}A+Bq⇌Cq+D diffusion-influenced reversible reaction for a geminate pair, a neutral and a charged particle, is investigated in three dimensions. The probability density functions, the rates of reactions, and the survival probabilities of individual particles are analytically derived in the Laplace domain in terms of series solutions. The long-time kinetics of probability density functions and rates of reactions in rescaled forms shows a kinetic transition behavior from a t−3/2 power law to a t−3/2et increase when the condition \documentclass[12pt]{minimal}\begin{document}$D_1F_1^2 \le D_2F_2^2$\end{document}D1F12≤D2F22, which depends on the diffusivities of particles and the external electric fields, changes to \documentclass[12pt]{minimal}\begin{document}$D_1F_1^2 > D_2F_2^2$\end{document}D1F12>D2F22. In the transition region \documentclass[12pt]{minimal}\begin{document}$D_1F_1^2 = D_2F_2^2$\end{document}D1F12=D2F22, the long-time behavior also shows a t−3/2 power law decay but with a different value of the prefactor. The rescaled survival probabilities only exhibit an exponentially increasing behavior at long times with no dependence on the various values of parameters.
On the spatial stability of a liquid jet in the presence of vapor cavities
Authors: Lü Ming , Ning Zhi , Lu Mei , Yan Kai , Fu Juan , Sun Chunhua
Published: November 2013

A dispersion equation describing the effect of temperature differences on the stability of three-dimensional cylindrical liquid jets in the presence of vapor cavities is presented by the use of linear stability analysis. The mathematical model and its solving method are verified by comparing them with the data in the literature, and then the effect of temperature differences between jet and surrounding gas on the spatial stability of liquid jet is investigated. Some conclusions can be drawn from the results of this investigation: (1) the temperature difference destabilizes the liquid jet when the jet liquid is cooler than the surrounding gas, (2) the smallest atomized droplet without taking into account the effect of temperature differences is significantly larger than that when the effect of temperature differences is taken into account, (3) the effect of temperature differences on the stability of liquid jet has little relationship with azimuthal wave modes, (4) cavitation destabilizes the liquid jet when the value of the bubble volume fraction is not greater than 0.1 (0 ≤ α ≤ 0.1), and the temperature difference can weaken this effect of cavitation on the stability of liquid jet, and (5) cavitation is responsible for generating smaller droplets, the effect of cavitation on the critical wave number with and without taking into account the effect of temperature differences is quite different, and temperature difference is likely to fully restrain the effect of cavitation on the critical wave number; however, cavitation is again responsible for generating smaller droplets despite the effect of temperature differences when the bubble volume fraction α = 0.1. These findings may explain some observations of practical atomizer performance.
Pinhole mediated electrical transport across LaTiO3/SrTiO3 and LaAlO3/SrTiO3 oxide hetero-structures
Authors: Kumar Pramod , Dogra Anjana , Toutam Vijaykumar
Published: November 2013

Metal-insulator-metal configuration of LaTiO3/SrTiO3 and LaAlO3/SrTiO3 hetero-structures between two dimensional electron gas formed at the interface and different area top electrodes is employed for Conductive Atomic force microscopy (CAFM) imaging, Current–Voltage (I-V), and Capacitance-Voltage (C-V) spectroscopy. Electrode area dependent I-V characteristics are observed for these oxide hetero-structures. With small area electrodes, rectifying I-V characteristics are observed, compared to, both tunneling and leakage current characteristics for large area electrodes. CAFM mapping confirmed the presence of pinholes on both surfaces. Resultant I-V characteristics have a contribution from both tunneling and leakage due to pinholes.
Magnetic reconnection under anisotropic magnetohydrodynamic approximation
Authors: Hirabayashi K. , Hoshino M.
Published: November 2013

We study the formation of slow-mode shocks in collisionless magnetic reconnection by using one- and two-dimensional collisionless MHD codes based on the double adiabatic approximation and the Landau closure model. We bridge the gap between the Petschek-type MHD reconnection model accompanied by a pair of slow shocks and the observational evidence of the rare occasion of in-situ slow shock observations. Our results showed that once magnetic reconnection takes place, a firehose-sense (p∥>p⊥) pressure anisotropy arises in the downstream region, and the generated slow shocks are quite weak comparing with those in an isotropic MHD. In spite of the weakness of the shocks, however, the resultant reconnection rate is 10%–30% higher than that in an isotropic case. This result implies that the slow shock does not necessarily play an important role in the energy conversion in the reconnection system and is consistent with the satellite observation in the Earth's magnetosphere.
The effect of Ta doping in polycrystalline TiOx and the associated thin film transistor properties
Authors: Ok Kyung-Chul , Park Yoseb , Chung Kwun-Bum , Park Jin-Seong
Published: November 2013

Tantalum (Ta) is suggested to act as an electron donor and crystal phase stabilizer in titanium oxide (TiOx). A transition occurs from an amorphous state to a crystalline phase at an annealing temperature above 300 °C in a vacuum ambient. As the annealing temperature increases from 300 °C to 450 °C, the mobility increases drastically from 0.07 cm2/Vs to 0.61 cm2/Vs. The remarkable enhancement of thin film transistor performance is suggested to be due to the splitting of Ti 3d band orbitals as well as the increase in Ta5+ ions that can act as electron donors.
Absolute distance sensing by two laser optical interferometry
Authors: Thurner Klaus , Braun Pierre-François , Karrai Khaled
Published: November 2013

We have developed a method for absolute distance sensing by two laser optical interferometry. A particularity of this technique is that a target distance is determined in absolute and is no longer limited to within an ambiguity range affecting usually multiple wavelength interferometers. We implemented the technique in a low-finesse Fabry-Pérot miniature fiber based interferometer. We used two diode lasers, both operating in the 1550 nm wavelength range. The wavelength difference is chosen to create a \documentclass[12pt]{minimal}\begin{document}$\rm 25\, \mu m$\end{document}25μm long periodic beating interferometric pattern allowing a nanometer precise position measurement but limited to within an ambiguity range of \documentclass[12pt]{minimal}\begin{document}$\rm 25 \, \mu m$\end{document}25μm. The ambiguity is then eliminated by scanning one of the wavelengths over a small range (3.4 nm). We measured absolute distances in the sub-meter range and this with just few nanometer repeatability.
Cascaded target normal sheath acceleration
Authors: Wang W. P. , Shen B. F. , Zhang X. M. , Wang X. F. , Xu J. C. , Zhao X. Y. , Yu Y. H. , Yi L. Q. , Shi Y. , Zhang L. G. , Xu T. J. , Xu Z. Z.
Published: November 2013

A cascaded target normal sheath acceleration (TNSA) scheme is proposed to simultaneously increase energy and improve energy spread of a laser-produced mono-energetic proton beam. An optimum condition that uses the maximum sheath field to accelerate the center of the proton beam is theoretically found and verified by two-dimensional particle-in-cell simulations. An initial 10 MeV proton beam is accelerated to 21 MeV with energy spread decreased from 5% to 2% under the optimum condition during the process of the cascaded TNSA. The scheme opens a way to scale proton energy lineally with laser energy.
Iodine doping effects on the lattice thermal conductivity of oxidized polyacetylene nanofibers
Authors: Bi Kedong , Weathers Annie , Matsushita Satoshi , Pettes Michael T. , Goh Munju , Akagi Kazuo , Shi Li
Published: November 2013

Thermal transport in oxidized polyacetylene (PA) nanofibers with diameters in the range between 74 and 126 nm is measured with the use of a suspended micro heater device. With the error due to both radiation and contact thermal resistance corrected via a differential measurement procedure, the obtained thermal conductivity of oxidized PA nanofibers varies in the range between 0.84 and 1.24 W m−1 K−1 near room temperature, and decreases by 40%–70% after iodine doping. It is also found that the thermal conductivity of oxidized PA nanofibers increases with temperature between 100 and 350 K. Because of exposure to oxygen during sample preparation, the PA nanofibers are oxidized to be electrically insulating before and after iodine doping. The measurement results reveal that iodine doping can result in enhanced lattice disorder and reduced lattice thermal conductivity of PA nanofibers. If the oxidation issue can be addressed via further research to increase the electrical conductivity via doping, the observed suppressed lattice thermal conductivity in doped polymer nanofibers can be useful for the development of such conducting polymer nanostructures for thermoelectric energy conversion.
Genomic DNA characterization of pork spleen by Raman spectroscopy
Authors: Guzmán-Embús D. A. , Orrego Cardozo M. , Vargas-Hernández C.
Published: November 2013

In this paper, the study of Raman signal enhancement due to interaction between ZnO rods and pork spleen DNA is reported. ZnO microstructures were synthesized by the Sol-Gel method and afterward combined with porcine spleen DNA extracted in the previous stages, following standardized cell lysis, deproteinization, and precipitation processes. Raman spectroscopy was used for the characterization of structures of ZnO and ZnO-DNA complex, and the results show the respective bands of ZnO wurtzite hexagonal phase for modes E2 (M), A1(TO), E2(High), E1(LO), and 2LO. Due to the SERS effect in the spectral range from 200 to 1800 cm,−1 Raman bands caused by vibrations of the deoxyribose C-O-C binding were also observed, producing deformation of the ring as shown in the 559 cm−1 peak. The broad band at 782 cm−1, together with the complex vibration of the string 5'-COPO-C3′, is over a wide band of thymine (790 cm−1) or cytosine (780 cm−1). A prominent band near 1098 cm−1 assigned to symmetric stretching vibration phosphodioxy group (PO2−) DNA backbone is most favoured in intensity by the addition of ZnO particles originated by the SERS effect. This effect suggests a possible mechanism for enhancing the Raman signal due to the electromagnetic interaction between a DNA molecule and the flat surface of the ZnO rod.
Subband structure of two-dimensional electron gases in SrTiO3
Authors: Raghavan Santosh , James Allen S. , Stemmer Susanne
Published: November 2013

Tunneling between two parallel, two-dimensional electron gases (2DEGs) in a complex oxide heterostructure containing a large, mobile electron density of ∼3 × 1014 cm−2 is used to probe the subband structure of the 2DEGs. Temperature-dependent current-voltage measurements are performed on SrTiO3/GdTiO3/SrTiO3 junctions, where GdTiO3 serves as the tunnel barrier, and each interface contains a high-density 2DEG. Resonant tunneling features in the conductance and its derivative occur when subbands on either side of the barrier align in energy as the applied bias is changed, and are used to analyze subband energy spacings in the two 2DEGs. We show that the results agree substantially with recent theoretical predictions for such interfaces.
Note: On the relation between Lifson-Jackson and Derrida formulas for effective diffusion coefficient
Authors: Kalnin Juris R. , Berezhkovskii Alexander M.
Published: November 2013

The Lifson-Jackson formula provides the effective free diffusion coefficient for a particle diffusing in an arbitrary one-dimensional periodic potential. Its counterpart, when the underlying dynamics is described in terms of an unbiased nearest-neighbor Markovian random walk on a one-dimensional periodic lattice is given by the formula obtained by Derrida. It is shown that the latter formula can be considered as a discretized version of the Lifson-Jackson formula with correctly chosen position-dependent diffusion coefficient.
Near-field thermal radiation between hyperbolic metamaterials: Graphite and carbon nanotubes
Authors: Liu X. L. , Zhang R. Z. , Zhang Z. M.
Published: November 2013

The near-field radiative heat transfer for two hyperbolic metamaterials, namely, graphite and vertically aligned carbon nanotubes (CNTs), is investigated. Graphite is a naturally existing uniaxial medium, while CNT arrays can be modeled as an effective anisotropic medium. Different hyperbolic modes can be separately supported by these materials in certain infrared regions, resulting in a strong enhancement in near-field heat transfer. It is predicted that the heat flux between two CNT arrays can exceed that between SiC plates at any vacuum gap distance and is about 10 times higher with a 10 nm gap.
Encapsulated gate-all-around InAs nanowire field-effect transistors
Authors: Sasaki Satoshi , Tateno Kouta , Zhang Guoqiang , Suominen Henri , Harada Yuichi , Saito Shiro , Fujiwara Akira , Sogawa Tetsuomi , Muraki Koji
Published: November 2013

We report the fabrication of lateral gate-all-around InAs nanowire field-effect transistors whose gate overlaps the source and drain electrodes and thus fully encapsulates the nanowire channel. They feature large drive current and transconductance that surpass those of conventional non-gate-overlap devices. The improved device characteristics can be attributed to the elimination of access resistance associated with ungated segments between the gate and source/drain electrodes. Our data also reveal a correlation between the normalized transconductance and the threshold voltage, which points to a beneficial effect of our wet-etching procedure performed prior to the atomic-layer-deposition of the gate dielectric.
Superconducting magnet performance for 28 GHz electron cyclotron resonance ion source developed at the Korea Basic Science Institute
Authors: Park Jin Yong , Choi Seyong , Lee Byoung-Seob , Yoon Jang-Hee , Ok Jung-Woo , Kim Byoung Chul , Shin Chang Seouk , Ahn Jung Keun , Won Mi-Sook
Published: November 2013

A superconducting magnet for use in an electron cyclotron resonance ion source was developed at the Korea Basic Science Institute. The superconducting magnet is comprised of three solenoids and a hexapole magnet. According to the design value, the solenoid magnets can generate a mirror field, resulting in axial magnetic fields of 3.6 T at the injection area and 2.2 T at the extraction region. A radial field strength of 2.1 T can also be achieved by hexapole magnet on the plasma chamber wall. NbTi superconducting wire was used in the winding process following appropriate techniques for magnet structure. The final assembly of the each magnet involved it being vertically inserted into the cryostat to cool down the temperature using liquid helium. The performance of each solenoid and hexapole magnet was separately verified experimentally. The construction of the superconducting coil, the entire magnet assembly for performance testing and experimental results are reported herein.
Computational study of imperfect networks using a coarse-grained model
Authors: Sliozberg Yelena R. , Chantawansri Tanya L.
Published: November 2013

The structural and mechanical properties of imperfect entangled polymer networks with various fractions of elastically active chains are studied using a generic coarse-grained model. Network topology is analyzed at various degrees of cross-linking and correlated with the mechanical response under uniaxial deformation at various strain rates. We found excellent agreement between results obtained from the structural analysis and from fitting to stress relaxation data. The relaxation tensile modulus at various engineering strains was also calculated as a function of the fraction of active strands. Results indicate that the mechanical and viscoelastic properties of entangled polymer networks are susceptible to variation in the network structure, where defects can affect the mechanical response especially at low strain rates and the relaxation behavior at long times.
Pervasive liquid metal based direct writing electronics with roller-ball pen
Authors: Zheng Yi , Zhang Qin , Liu Jing
Published: November 2013

A roller-ball pen enabled direct writing electronics via room temperature liquid metal ink was proposed. With the rolling to print mechanism, the metallic inks were smoothly written on flexible polymer substrate to form conductive tracks and electronic devices. The contact angle analyzer and scanning electron microscope were implemented to disclose several unique inner properties of the obtained electronics. An ever high writing resolution with line width and thickness as 200 μm and 80 μm, respectively was realized. Further, with the administration of external writing pressure, GaIn24.5 droplets embody increasing wettability on polymer which demonstrates the pervasive adaptability of the roller-ball pen electronics.
Communication: Reduced density matrices in molecular systems: Grand-canonical electron states
Authors: Bochicchio Roberto C. , Miranda-Quintana Ramón A. , Rial Diego
Published: November 2013

Grand-canonical like descriptions of many electron atomic and molecular open systems which are characterized by a non-integer number of electrons are presented. Their associated reduced density matrices (RDMs) are obtained by introducing the contracting mapping for this type of distributions. It is shown that there is loss of information when connecting RDMs of different order by partial contractions. The energy convexity property of these systems simplifies the description. Consequently, this formulation opens the possibility to a new look for chemical descriptors such as chemical potential and reactivity among others. Examples are presented to discuss the theoretical aspects of this work.
Thermopower of nanocrystalline germanium/hydrogenated amorphous silicon composite thin films
Authors: Bodurtha K. , Kakalios J.
Published: November 2013

Thin films consisting of hydrogenated amorphous silicon (a-Si:H), in which germanium nanocrystals (nc-Ge) are embedded, have been synthesized using a dual-chamber co-deposition system. The thermopower and conductivity are studied as the germanium crystal fraction XGe is systematically increased. For XGe < 10%, the thermopower is n-type (as found in undoped a-Si:H), while for XGe > 25% p-type transport is observed. For films with 10% < XGe < 25%, the thermopower shifts from n-type to p-type as the temperature is lowered from 450 K to 350 K. The n-type to p-type transition is sharper than expected from a standard two-channel parallel conduction model for charge transport.
High levels of diversity for seed and forage production exist in Cullen australasicum, a potential new perennial forage legume for dry environments in southern Australia
Authors: Humphries Alan W. , Hughes Stephen J. , Nair Ramakrishnan M. , Kobelt Eric , Sandral Graeme
Published: November 2013

The seed and forage production of a diverse group of the perennial forage legume Cullen spp., collected in southern Australia, was assessed with the aim of discovering diversity for exploitation in future breeding programs. Eighty ecotypes were assessed at the Waite Institute in South Australia, using replicated, spaced-plant field trials, between 2008 and 2012. Seed production in collected ecotypes of Cullen (Expt 1) ranged from 0 to 485 kg ha–1 for windrowed seed yield and from 0 to 790 kg ha–1 for total seed yield, which included vacuum-harvested seed from pods that had fallen to the ground. Individual plants were selected for seed production from their original populations, and the seed and fodder production of their progeny was evaluated in a further field experiment (Expt 2). Moderate to high heritability estimates were recorded for seed production traits. Seed production in progeny families ranged from 0 to1 423 kg ha–1 and was highly correlated with the number of seeds per inflorescence (r = 0.85) and forage yield (r = 0.59). Edible biomass, measured using the Adelaide visual appraisal method, ranged from 50 to 906 g dry weight  (DW)  plant–1 in parent ecotypes and from 404 to 1248 g DW plant–1 in the selected family progenies. Disease infection with anthracnose (Colletotrichum trifolii) caused considerable damage to plants in Expt 1, resulting in the death of all plants of 10 ecotypes, and infection with Alfalfa mosaic virus in Expt 2 was linked to the death of 67 individuals. The results are discussed in relation to breeding C. australasicum for increased seed yield and disease resistance to overcome these deficiencies as barriers to commercial adoption.
Evaluating long-term impact of land use on selected soil physical quality indicators
Authors: Abu S. T.
Published: November 2013

This paper presents findings of comparative evaluation of selected soil physical quality (SPQ) indicators, obtained from fields subjected to: >50 years of cultivation of three perennial pasture grasses (i) Digitaria smutsii (DS), (ii) Brachiaria decumbens (BD), and (iii) Andropogon gayanus (AG); (iv) >50 years of continuous cultivation (CC) of cereals–legumes; and (v) >20 years of natural fallow (NF). The study was aimed at identifying the land-use system having optimal values for SPQ. Fields under CC had the highest bulk density, and the lowest total porosity (PORt) and macroporosity (PORp), field capacity (FC), and available water capacity (AWC). Perennial pasture grasses fields had significantly higher organic carbon, PORt, FC, AWC, and saturated hydraulic conductivity, and, hence, had better SPQ than CC fields and, in some instances, NF fields. The usefulness of ratios FC/PORt = 0.66 and ACt/PORt = 0.34 as additional indicators for assessing soil response to land-use systems was not proven in this study, and therefore, further studies should be conducted on the subject matter. Pasture grasses improved SPQ values relative to continuous cereal–legume cropping and fallow. The SPQ under CC and NF fields might be best improved by applying organic matter.
Modelling oxygen transport in soil with plant root and microbial oxygen consumption: depth of oxygen penetration
Authors: Cook F. J. , Knight J. H. , Kelliher F. M.
Published: November 2013

A set of equations governing oxygen diffusion and consumption in soils has been developed to include microbial and plant-root sinks. The dependent variable is the transformed oxygen concentration, which is the difference between the gaseous concentration and a scaled value of the aqueous oxygen concentration at the root–soil interface. The results show how, as the air-filled porosity decreases, the reduced oxygen flux causes the depth of extinction to decrease. The results also show how the depth of extinction at a particular value of soil water content decreases with increasing temperature, due to increased microbial respiration. The critical value of water content at which the oxygen concentration goes to extinction at a finite depth was compared with alternative calculations with only a microbial sink. By ignoring the feedback of oxygen concentration on root uptake, the alternative calculations yielded substantially higher critical values of water content at all temperatures. Two soil oxygen diffusion coefficient functions from the literature were compared and shown to give significantly different critical values of water content for fine-textured soils, one more realistic than the other. A single relationship between the extinction depth and the ratio of the water content to the critical value was shown to apply for all temperatures and soil textures. The oxygen profiles were used along with a function relating redox potential to oxygen concentration to generate redox potential profiles. This application of the model could be useful in explaining soil biochemical processes in soils. For one such process, denitrification, the depth at which a critical oxygen concentration is reached was calculated as a function of the air-filled porosity and temperature of the soil. The implications of the critical value of soil water content in terms of water-filled pore space and matric potential are discussed in relation to the diffusion coefficient functions and recent literature.
Spawning season movements of Macquarie perch (Macquaria australasica) in the Yarra River, Victoria
Authors: Koster W. M. , Dawson D. R. , Morrongiello J. R. , Crook D. A.
Published: November 2013

The Macquarie perch (Macquaria australasica) is a threatened fish species that inhabits rivers and impoundments in south-eastern Australia. Previous studies have shown that Macquarie perch in impoundments exhibit synchronised upstream spawning migrations to shallow, fast-flowing habitats in the lower reaches of inflowing streams. There has been little study of movement behaviours of entirely riverine populations of Macquarie perch despite this being the species’ natural habitat. Here, radio-telemetry is used to test the hypothesis that riverine populations exhibit synchronised migrations during the spawning season. Thirty Macquarie perch in the Yarra River, Victoria, a translocated population outside of the species’ natural range, were radio-tagged before the late spring–early summer spawning season and their movements followed over a 10-month period (May 2011 to February 2012). Tagged fish typically occupied restricted reaches of stream (<450 m). Sixteen of the fish undertook occasional upstream or downstream movements (~250–1000 m) away from their usual locations, particularly associated with large flow variations during the spawning season. There was no evidence of synchronised migratory behaviour or movement of multiple fish to specific locations or habitats during the spawning season. Whilst further research over more years is needed to comprehensively document the spawning-related behaviours of riverine Macquarie perch, our study demonstrates that management of riverine populations of this threatened species cannot necessarily be based on the model of spawning behaviour developed for lacustrine populations.
A fully defined and scalable 3D culture system for human pluripotent stem cell expansion and differentiation
Authors: Lei Yuguo , Schaffer David V.
Published: November 2013

Significance

Human pluripotent stem cells can be cultured in vitro and differentiated into presumably all cell types of the human body, and they therefore represent highly promising cell sources for biomedical applications such as cell therapies, tissue engineering, and drug discovery. These applications require large numbers of high-quality cells, and we report an efficient, defined, scalable, and good manufacturing practice-compatible 3D system for the production of human pluripotent stem cells and their progeny. The ease of use and flexible scalability of this system makes it suitable for numerous applications from the laboratory toward the clinic.
Rationally designed inhibitor targeting antigen-trimming aminopeptidases enhances antigen presentation and cytotoxic T-cell responses
Authors: Zervoudi Efthalia , Saridakis Emmanuel , Birtley James R. , Seregin Sergey S. , Reeves Emma , Kokkala Paraskevi , Aldhamen Yasser A. , Amalfitano Andrea , Mavridis Irene M. , James Edward , Georgiadis Dimitris , Stratikos Efstratios
Published: November 2013

Significance

The human immune system fights disease by eradicating sick cells after first recognizing that they are infected or cancerous. This is achieved by specialized cells that detect on the surface of other cells small molecules called antigenic peptides. Pathogens and cancer can evade the immune system by stopping the generation of antigenic peptides. We designed, synthesized and evaluated artificial small molecules that can effectively block a group of enzymes that are key for the production or destruction of antigenic peptides. We show that these compounds can enhance the generation of antigenic peptides in cells and enhance the immune system reaction toward cancer. Inhibitors of this kind may provide a new approach to coax the immune system into recognizing and eliminating cancer cells.
Estimating functional connectivity in an electrically coupled interneuron network
Authors: Alcami Pepe , Marty Alain
Published: November 2013

Significance

Certain classes of central neurons, notably interneurons, are linked together by electrical synapses made by gap junctions, which play an important role in network function. Modeling electrically coupled interneuron networks has been limited by a lack of knowledge of the number of cells directly connected to a reference neuron and of the extent of charge redistribution in the network. We show that capacitive currents can be used to derive such information. We illustrate this method, using the network formed by cerebellar molecular layer interneurons. We establish a quantitative model of the network, and we estimate the influence of gap junctions on network excitability. The method may be generally applicable to sparsely electrically coupled networks, particularly if they are planar.
Oxytocic plant cyclotides as templates for peptide G protein-coupled receptor ligand design
Authors: Koehbach Johannes , O’Brien Margaret , Muttenthaler Markus , Miazzo Marion , Akcan Muharrem , Elliott Alysha G. , Daly Norelle L. , Harvey Peta J. , Arrowsmith Sarah , Gunasekera Sunithi , Smith Terry J. , Wray Susan , Göransson Ulf , Dawson Philip E. , Craik David J. , Freissmuth Michael , Gruber Christian W.
Published: November 2013

Significance

G protein-coupled receptors (GPCRs) are promising drug targets: >30% of the currently marketed drugs elicit their actions by binding to these transmembrane receptors. However, only ∼10% of all GPCRs are targeted by approved drugs. Resorting to plant-derived compounds catalogued by ethnopharmacological analyses may increase this repertoire. We provide a proof of concept by analyzing the uterotonic action of an herbal remedy used in traditional African medicine. We identified cyclic peptides, investigated the molecular mechanisms underlying their uterotonic activity, and report an oxytocic plant peptide that modulates the human oxytocin/vasopressin receptors. This naturally occurring peptide served as a template for the design of an oxytocin-like nonapeptide with enhanced receptor selectivity, highlighting the potential of cyclotides for the discovery of peptide-based GPCR ligands.
Loss of
caspase-2
augments lymphomagenesis and enhances genomic instability in
Atm
-deficient mice
Authors: Puccini Joseph , Shalini Sonia , Voss Anne K. , Gatei Magtouf , Wilson Claire H. , Hiwase Devendra K. , Lavin Martin F. , Dorstyn Loretta , Kumar Sharad
Published: November 2013

Significance

The cysteine protease caspase-2 has been implicated in the suppression of oncogene-mediated tumor formation. However, the mechanisms underlying the function of caspase-2 as a tumor suppressor are not well defined. In this study, we use a well-characterized mouse lymphoma model and demonstrate a critical role for caspase-2 in maintaining genome stability and in the suppression of tumorigenesis following loss of the essential DNA repair gene ataxia telangiectasia mutated (
Atm
). Our findings suggest that caspase-2 cooperates with ATM to suppress genomic instability, oxidative stress, and tumor progression.
RAN proteins and RNA foci from antisense transcripts in
C9ORF72
ALS and frontotemporal dementia
Authors: Zu Tao , Liu Yuanjing , Bañez-Coronel Monica , Reid Tammy , Pletnikova Olga , Lewis Jada , Miller Timothy M. , Harms Matthew B. , Falchook Annet E. , Subramony S. H. , Ostrow Lyle W. , Rothstein Jeffrey D. , Troncoso Juan C. , Ranum Laura P. W.
Published: November 2013

Significance

A GGGGCC expansion mutation located in intron 1 of
chromosome 9 ORF 72
(
C9ORF72
) was recently described as a common cause of familial amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD). We show that this single mutation results in the accumulation of sense and antisense RNA foci plus six expansion proteins expressed by repeat-associated non-ATG (RAN) translation. RNAs accumulate in nuclear foci and the RAN proteins form cytoplasmic aggregates in neurons that often cluster in affected brain regions. These results indicate that bidirectional transcription and RAN translation are fundamental pathologic features of
C9ORF72
ALS/FTD. Additionally these data have broad implications that change our understanding of how microsatellite expansion mutations are expressed in patient cells and how they cause disease.
Greenland ice sheet motion insensitive to exceptional meltwater forcing
Authors: Tedstone Andrew J. , Nienow Peter W. , Sole Andrew J. , Mair Douglas W. F. , Cowton Thomas R. , Bartholomew Ian D. , King Matt A.
Published: November 2013

Significance

During summer, meltwater generated on the Greenland ice sheet surface accesses the ice sheet bed, lubricating basal motion and resulting in periods of faster ice flow. However, the net impact of varying meltwater volumes upon seasonal and annual ice flow, and thus sea level rise, remains unclear. In 2012, despite record ice sheet runoff, including two extreme melt events, ice at a land-terminating margin flowed more slowly than in the average melt year of 2009, due principally to slower winter flow following faster summer flow. Our findings suggest that annual motion of land-terminating margins of the ice sheet, and thus the projected dynamic contribution of these margins to sea level rise, is insensitive to melt volumes commensurate with temperature projections for 2100.
Distribution of directional change as a signature of complex dynamics
Authors: Burov Stanislav , Tabei S. M. Ali , Huynh Toan , Murrell Michael P. , Philipson Louis H. , Rice Stuart A. , Gardel Margaret L. , Scherer Norbert F. , Dinner Aaron R.
Published: November 2013

Significance

Since Einstein’s seminal work in 1905, the main means of characterizing stochastic processes has been the mean square displacement (MSD). However, this order parameter fails to capture many features of dynamics at the forefront of science today, ranging from glassy relaxation to active transport in biological cells. Although there have been several studies seeking to go beyond the MSD, such studies have not made full use of the information available in individual trajectories in two (or more) dimensions, as are now commonly obtained in particle tracking experiments. Here, we introduce an approach that quantifies directional properties of complex motions and discover striking correlations in a number of condensed phase systems.