bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and investigation of a multichannel laser-triggered vacuum switch
Authors: Fan Wenfang , He Zhenghao , Mao Xiaopo
Published: March 2016

A laser-triggered vacuum switch (LTVS) is an advanced closing switch with nanosecond delay and jitter. In order to enhance hold-off voltage and extend the service lifetime of an LTVS, we designed a multichannel laser-triggered vacuum switch (MLTVS) utilizing a cone-shaped target electrode placed on the cathode platform. The fabrication and testing of the MLTVS is described in this paper. Experimental results show that the working voltage of the MLTVS with a gap distance of 12 mm is from 30 V to 20 kV. The threshold energy for triggering the switch is 0.4 mJ corresponding to a peak power density of 27.9 MW/cm2. The triggering lifetime of a spot can reach up to 18 000 shots. In addition, the relationship between triggering lifetime and target materials is analyzed using a field emission scanning electron microscope. A hypothesis of the vacuum gap’s triggering mechanism is discussed based on the measured results.
Role of atomistic structure in the stochastic nature of conductivity in substoichiometric tantalum pentoxide
Authors: Bondi Robert J. , Fox Brian P. , Marinella Matthew J.
Published: March 2016

First-principles calculations of electrical conductivity (σo) are revisited to determine the atomistic origin of its stochasticity in a distribution generated from sampling 14 ab-initio molecular dynamics configurations from 10 independently quenched models (n = 140) of substoichiometric amorphous Ta2O5, where each structure contains a neutral O monovacancy (VO0). Structural analysis revealed a distinct minimum Ta-Ta separation (dimer/trimer) corresponding to each VO0 location. Bader charge decomposition using a commonality analysis approach based on the σo distribution extremes revealed nanostructural signatures indicating that both the magnitude and distribution of cationic charge on the Ta subnetwork have a profound influence on σo. Furthermore, visualization of local defect structures and their electron densities reinforces these conclusions and suggests σo in the amorphous oxide is best suppressed by a highly charged, compact Ta cation shell that effectively screens and minimizes localized VO0 interaction with the a-Ta2O5 network; conversely, delocalization of VO0 corresponds to metallic character and high σo. The random network of a-Ta2O5 provides countless variations of an ionic configuration scaffold in which small perturbations affect the electronic charge distribution and result in a fixed-stoichiometry distribution of σo; consequently, precisely controlled and highly repeatable oxide fabrication processes are likely paramount for advancement of resistive memory technologies.
Development of a Ne gas target for 22Na production by proton irradiation
Authors: Mandal Bidhan Ch. , Barua Luna , Das Sujata Saha , Pal Gautam
Published: March 2016

The article presents the design and development of a neon gas target for the production of 22Na using a proton beam from the room temperature cyclotron in Variable Energy Cyclotron Centre, Kolkata. The target design is made to handle a beam power of 85 W (17 MeV, 5 μA). The design is based on simulation using the computer code FLUKA for the beam dump and CFD-CFX for target cooling. The target has been successfully used for the production of 22Na in a 6 day long 17 MeV, 5 μA proton irradiation run.
Effects of oxygen background pressure on the stoichiometry of a LaGaO3 laser ablation plume investigated by time and spectrally resolved two-dimensional imaging
Authors: Sambri A. , Aruta C. , Di Gennaro E. , Wang X. , Scotti di Uccio U. , Miletto Granozio F. , Amoruso S.
Published: March 2016

The plume expansion dynamics strongly affects the growth and the chemistry of pulsed laser deposited thin films. The interaction with the background gas determines the kinetic energy of the species impinging on the substrate, their angular broadening, the plasma chemistry, and eventually the cations stoichiometric ratio in oxide films. Here, we exploit two-dimensional, spectrally resolved plume imaging to characterize the diverse effects of the oxygen background pressure on the expansion dynamics of La, Ga, and LaO species during pulsed laser deposition of LaGaO3. The propagation of the ablated species towards the substrate is studied for background oxygen pressures ranging from high vacuum up to ≈10−1 mbar. Our experimental results show specie-dependent effects of the background gas on the angular distribution of the precursors within the plume. These findings suggest that even in the presence of a stoichiometric ablation and of a globally stoichiometric plume, cations off-stoichiometry can take place in the forefront portion of the plume impinging on the substrate. We show that such effect can be compensated by a proper choice of process parameters.
Simulations of laminar boundary-layer flow encountering large-scale surface indentions
Authors: Beratlis N. , Balaras E. , Squires K. , Vizard A.
Published: March 2016

The transition from laminar to turbulent flow over dimples and grooves has been investigated through a series of direct numerical simulations. Emphasis has been given to the mechanism of transition and the momentum transport in the post-dimple boundary layer. It has been found that the dimple geometry plays an important role in the evolution of the turbulent boundary layer downstream. The mechanism of transition in all cases is that of the reorientation of the spanwise vorticity into streamwise oriented structures resembling hairpin vortices commonly encountered in wall bounded turbulent flows. Although qualitatively the transition mechanism amongst the three different cases is similar, important quantitative differences exist. It was shown that two-dimensional geometries like a groove are more stable than three-dimensional geometries like a dimple. In addition, it was found that the cavity geometry controls the initial thickness of the boundary layer and practically results in a shift of the virtual origin of the turbulent boundary layer. Important differences in the momentum transport downstream of the dimples exist but in all cases the boundary layer grows in a self-similar manner.
Structures and chemical bonding of B3O3−/0 and B3O3H−/0: A combined photoelectron spectroscopy and first-principles theory study
Authors: Zhao Li-Juan , Tian Wen-Juan , Ou Ting , Xu Hong-Guang , Feng Gang , Xu Xi-Ling , Zhai Hua-Jin , Li Si-Dian , Zheng Wei-Jun
Published: March 2016

We present a combined photoelectron spectroscopy and first-principles theory study on the structural and electronic properties and chemical bonding of B3O3−/0 and B3O3H−/0 clusters. The concerted experimental and theoretical data show that the global-minimum structures of B3O3 and B3O3H neutrals are very different from those of their anionic counterparts. The B3O3− anion is characterized to possess a V-shaped OB–B–BO chain with overall C2v symmetry (1A), in which the central B atom interacts with two equivalent boronyl (B≡O) terminals via B–B single bonds as well as with one O atom via a B=O double bond. The B3O3H− anion has a Cs (2A) structure, containing an asymmetric OB–B–OBO zig-zag chain and a terminal H atom interacting with the central B atom. In contrast, the C2v (1a) global minimum of B3O3 neutral contains a rhombic B2O2 ring with one B atom bonded to a BO terminal and that of neutral B3O3H (2a) is also of C2v symmetry, which is readily constructed from C2v (1a) by attaching a H atom to the opposite side of the BO group. The H atom in B3O3H−/0 (2A and 2a) prefers to interact terminally with a B atom, rather than with O. Chemical bonding analyses reveal a three-center four-electron (3c-4e) π hyperbond in the B3O3H− (2A) cluster and a four-center four-electron (4c-4e) π bond (that is, the so-called o-bond) in B3O3 (1a) and B3O3H (2a) neutral clusters.
Plasma jet printing for flexible substrates
Authors: Gandhiraman Ram P. , Singh Eric , Diaz-Cartagena Diana C. , Nordlund Dennis , Koehne Jessica , Meyyappan M.
Published: March 2016

Recent interest in flexible electronics and wearable devices has created a demand for fast and highly repeatable printing processes suitable for device manufacturing. Robust printing technology is critical for the integration of sensors and other devices on flexible substrates such as paper and textile. An atmospheric pressure plasma-based printing process has been developed to deposit different types of nanomaterials on flexible substrates. Multiwalled carbon nanotubes were deposited on paper to demonstrate site-selective deposition as well as direct printing without any type of patterning. Plasma-printed nanotubes were compared with non-plasma-printed samples under similar gas flow and other experimental conditions and found to be denser with higher conductivity. The utility of the nanotubes on the paper substrate as a biosensor and chemical sensor was demonstrated by the detection of dopamine, a neurotransmitter, and ammonia, respectively.
Combined theoretical and experimental study of the valence, Rydberg, and ionic states of chlorobenzene
Authors: Palmer Michael H. , Ridley Trevor , Vrønning Hoffmann Søren , Jones Nykola C. , Coreno Marcello , de Simone Monica , Grazioli Cesare , Zhang Teng , Biczysko Malgorzata , Baiardi Alberto , Peterson Kirk A.
Published: March 2016

New photoelectron (PE) and ultra violet (UV) and vacuum UV (VUV) spectra have been obtained for chlorobenzene by synchrotron study with higher sensitivity and resolution than previous work and are subjected to detailed analysis. In addition, we report on the mass-resolved (2 + 1) resonance enhanced multiphoton ionization (REMPI) spectra of a jet-cooled sample. Both the VUV and REMPI spectra have enabled identification of a considerable number of Rydberg states for the first time. The use of ab initio calculations, which include both multi-reference multi-root doubles and singles configuration interaction (MRD-CI) and time dependent density functional theoretical (TDDFT) methods, has led to major advances in interpretation of the vibrational structure of the ionic and electronically excited states. Franck-Condon (FC) analyses of the PE spectra, including both hot and cold bands, indicate much more complex envelopes than previously thought. The sequence of ionic states can be best interpreted by our multi-configuration self-consistent field computations and also by comparison of the calculated vibrational structure of the B and C ionic states with experiment; these conclusions suggest that the leading sequence is the same as that of iodobenzene and bromobenzene, namely: X2B1(3b1−1) < A2A2(1a2−1) < B2B2(6b2−1) < C2B1(2b1−1). The absorption onset near 4.6 eV has been investigated using MRD-CI and TDDFT calculations; the principal component of this band is 1B2 and an interpretation based on the superposition of FC and Herzberg-Teller contributions has been performed. The other low-lying absorption band near 5.8 eV is dominated by a 1A1 state, but an underlying weak 1B1 state (πσ∗) is also found. The strongest band in the VUV spectrum near 6.7 eV is poorly resolved and is analyzed in terms of two ππ∗ states of 1A1 (higher oscillator strength) and 1B2 (lower oscillator strength) symmetries, respectively. The calculated vertical excitation energies of these two states are critically dependent upon the presence of Rydberg functions in the basis set, since both manifolds are strongly perturbed by the Rydberg states in this energy range. A number of equilibrium structures of the ionic and singlet excited states show that the molecular structure is less subject to variation than corresponding studies for iodobenzene and bromobenzene.
STM study of PTCDA on Sn/Si(111)-23×23
Authors: Zhang H. M. , Johansson L. S. O.
Published: March 2016

The electronic structures of perylene tetracarboxylic dianhydride on Sn/Si(111)-23×23 have been studied by scanning tunneling microscopy and spectroscopy. Individual molecules have been investigated at 0.15 ML, while at 0.3 ML molecules formed short rods. At 0.6 ML, the molecular rods interacted with each other, coupling with the substrate and forming a new 43×23 super structure. At 0.9 ML, the surface was further reconstructed and consisted of strips with two and three rods of molecules. We found that these surface structures are strongly modified by the molecule/substrate and the intermolecular interactions. As a result, the HOMO-LUMO gaps of these molecules change with respect to the phases and the thickness. For a single molecular layer of the 43×23 phase, the HOMO-LUMO levels were split with a gap of approximately 2.1 eV, which is caused by charge transfer from the substrate to the molecules.
Extreme ultra-violet burst, particle heating, and whistler wave emission in fast magnetic reconnection induced by kink-driven Rayleigh-Taylor instability
Authors: Chai Kil-Byoung , Zhai Xiang , Bellan Paul M.
Published: March 2016

A spatially localized energetic extreme ultra-violet (EUV) burst is imaged at the presumed position of fast magnetic reconnection in a plasma jet produced by a coaxial helicity injection source; this EUV burst indicates strong localized electron heating. A circularly polarized high frequency magnetic field perturbation is simultaneously observed at some distance from the reconnection region indicating that the reconnection emits whistler waves and that Hall dynamics likely governs the reconnection. Spectroscopic measurement shows simultaneous fast ion heating. The electron heating is consistent with Ohmic dissipation, while the ion heating is consistent with ion trajectories becoming stochastic.
On the quantum Landau collision operator and electron collisions in dense plasmas
Authors: Daligault Jérôme
Published: March 2016

The quantum Landau collision operator, which extends the widely used Landau/Fokker-Planck collision operator to include quantum statistical effects, is discussed. The quantum extension can serve as a reference model for including electron collisions in non-equilibrium dense plasmas, in which the quantum nature of electrons cannot be neglected. In this paper, the properties of the Landau collision operator that have been useful in traditional plasma kinetic theory and plasma transport theory are extended to the quantum case. We outline basic properties in connection with the conservation laws, the H-theorem, and the global and local equilibrium distributions. We discuss the Fokker-Planck form of the operator in terms of three potentials that extend the usual two Rosenbluth potentials. We establish practical closed-form expressions for these potentials under local thermal equilibrium conditions in terms of Fermi-Dirac and Bose-Einstein integrals. We study the properties of linearized quantum Landau operator, and extend two popular approximations used in plasma physics to include collisions in kinetic simulations. We apply the quantum Landau operator to the classic test-particle problem to illustrate the physical effects embodied in the quantum extension. We present useful closed-form expressions for the electron-ion momentum and energy transfer rates. Throughout the paper, similarities and differences between the quantum and classical Landau collision operators are emphasized.
Dynamic superhydrophobic behavior in scalable random textured polymeric surfaces
Authors: Moreira David , Park Sung-hoon , Lee Sangeui , Verma Neil , Bandaru Prabhakar R.
Published: March 2016

Superhydrophobic (SH) surfaces, created from hydrophobic materials with micro- or nano- roughness, trap air pockets in the interstices of the roughness, leading, in fluid flow conditions, to shear-free regions with finite interfacial fluid velocity and reduced resistance to flow. Significant attention has been given to SH conditions on ordered, periodic surfaces. However, in practical terms, random surfaces are more applicable due to their relative ease of fabrication. We investigate SH behavior on a novel durable polymeric rough surface created through a scalable roll-coating process with varying micro-scale roughness through velocity and pressure drop measurements. We introduce a new method to construct the velocity profile over SH surfaces with significant roughness in microchannels. Slip length was measured as a function of differing roughness and interstitial air conditions, with roughness and air fraction parameters obtained through direct visualization. The slip length was matched to scaling laws with good agreement. Roughness at high air fractions led to a reduced pressure drop and higher velocities, demonstrating the effectiveness of the considered surface in terms of reduced resistance to flow. We conclude that the observed air fraction under flow conditions is the primary factor determining the response in fluid flow. Such behavior correlated well with the hydrophobic or superhydrophobic response, indicating significant potential for practical use in enhancing fluid flow efficiency.
Aliovalent cation ordering, coexisting ferroelectric structures, and electric field induced phase transformation in lead-free ferroelectric Na0.5Bi0.5TiO3
Authors: Pan Jaysree , Niranjan Manish K. , Waghmare Umesh V.
Published: March 2016

Using first-principles calculations, we show that a specific chemical ordering of Na and Bi in Na0.5Bi0.5TiO3 is responsible for the co-existence of its ferroelectric phases with rhombohedral R3c and monoclinic Cc structures, which are relevant to its morphotropic phase boundary and large piezoelectric response. We identify the signatures of chemical ordering in the calculated phonon spectra and establish the prevalence of A-type ordering through comparison with experiment. We uncover a mechanism of the observed electric field induced Cc to lower energy R3c structural transformation promoted by a hybrid soft mode involving a combination of TiO6 rotations and a polar component.
Bipolar square-wave current source for transient electromagnetic systems based on constant shutdown time
Authors: Wang Shilong , Yin Changchun , Lin Jun , Yang Yu , Hu Xueyan
Published: March 2016

Cooperative work of multiple magnetic transmitting sources is a new trend in the development of transient electromagnetic system. The key is the bipolar current waves shutdown, concurrently in the inductive load. In the past, it was difficult to use the constant clamping voltage technique to realize the synchronized shutdown of currents with different peak values. Based on clamping voltage technique, we introduce a new controlling method with constant shutdown time. We use the rising time to control shutdown time and use low voltage power source to control peak current. From the viewpoint of the circuit energy loss, by taking the high-voltage capacitor bypass resistance and the capacitor of the passive snubber circuit into account, we establish the relationship between the rising time and the shutdown time. Since the switch is not ideal, we propose a new method to test the shutdown time by the low voltage, the high voltage and the peak current. Experimental results show that adjustment of the current rising time can precisely control the value of the clamp voltage. When the rising time is fixed, the shutdown time is unchanged. The error for shutdown time deduced from the energy consumption is less than 6%. The new controlling method on current shutdown proposed in this paper can be used in the cooperative work of borehole and ground transmitting system.
Wide range room temperature electroclinic liquid crystal mixture with large induced tilt and very small layer contraction
Authors: Debnath Asim , Sinha Debashis , Mandal Pradip Kumar
Published: March 2016

Optical polarizing microscopy, synchrotron X-ray scattering, and electro-optic studies in the SmA* phase of a formulated wide range room temperature liquid crystal mixture indicate a large electric field induced optical tilt up to 23.5° along with a very small contraction of smectic layers. Applied field primarily lifts the zero-field degeneracy of the azimuthal order of the molecules in smectic layers resulting in small layer contraction.
Efficient generation of sub-100 eV high-order harmonics from carbon molecules using infrared laser pulses
Authors: Fareed M. A. , Thiré N. , Mondal S. , Schmidt B. E. , Légaré F. , Ozaki T.
Published: March 2016

We demonstrate broad bandwidth and intense sub-100 eV high-order harmonics from diatomic carbon molecules driven by long-wavelength laser pulses. Up to now, one limitation of the intense carbon harmonic source driven by a 0.8 μm wavelength Ti:sapphire laser has been the low cutoff around ∼32 eV. In this paper, we show that this harmonic cutoff is extended to ∼70 eV by increasing the driving laser wavelength to 1.71 μm. Surprisingly, the carbon harmonic intensity is found to be high despite the long wavelength driving laser. Experiments show only ∼30% decrease in the harmonic intensity when changing the driving laser wavelength from 0.8 μm to 1.71 μm. Such intense sub-100 eV coherent X-rays would have important applications in various domains of science and technology.
Characterization of AlN/AlGaN/GaN:C heterostructures grown on Si(111) using atom probe tomography, secondary ion mass spectrometry, and vertical current-voltage measurements
Authors: Huber Martin , Daumiller Ingo , Andreev Andrei , Silvestri Marco , Knuuttila Lauri , Lundskog Anders , Wahl Michael , Kopnarski Michael , Bonanni Alberta
Published: March 2016

Complementary studies of atom probe tomography, secondary ion mass spectrometry, and vertical current-voltage measurements are carried out in order to unravel the influence of C-doping of GaN on the vertical leakage current of AlN/AlGaN/GaN:C heterostructures. A systematic increment of the vertical blocking voltage at a given current density is observed in the structures, when moving from the nominally undoped conditions—corresponding to a residual C-background of ∼1017 cm−3—to a C-content of ∼1019 cm−3 in the GaN layer. The value of the vertical blocking voltage saturates for C concentrations higher than ∼1019 cm−3. Atom probe tomography confirms the homogeneity of the GaN:C layers, demonstrating that there is no clustering at C-concentrations as high as 1020 cm−3. It is inferred that the vertical blocking voltage saturation is not likely to be related to C-clustering.
Electrically controlled pinning of Dzyaloshinskii-Moriya domain walls
Authors: Sato Koji , Tretiakov Oleg A.
Published: March 2016

We propose a method to all-electrically control a domain-wall position in a ferromagnetic nanowire with Dzyaloshinskii-Moriya interaction. The strength of this interaction can be controlled by an external electric field, which in turn allows a fine tuning of the pinning potential of a spin-spiral domain wall. It allows to create more mobile pinning sites and can also be advantageous for ultra-low power electronics.
Nature of exciton transitions in hexagonal boron nitride
Authors: Li J. , Cao X. K. , Hoffman T. B. , Edgar J. H. , Lin J. Y. , Jiang H. X.
Published: March 2016

In contrast to other III-nitride semiconductors GaN and AlN, the intrinsic (or free) exciton transition in hexagonal boron nitride (h-BN) consists of rather complex fine spectral features (resolved into six sharp emission peaks) and the origin of which is still unclear. Here, the free exciton transition (FX) in h-BN bulk crystals synthesized by a solution method at atmospheric pressure has been probed by deep UV time-resolved photoluminescence (PL) spectroscopy. Based on the separations between the energy peak positions of the FX emission lines, the identical PL decay kinetics among different FX emission lines, and the known phonon modes in h-BN, we suggest that there is only one principal emission line corresponding to the direct intrinsic FX transition in h-BN, whereas all other fine features are a result of phonon-assisted transitions. The identified phonon modes are all associated with the center of the Brillouin zone. Our results offer a simple picture for the understanding of the fundamental exciton transitions in h-BN.
Laser-induced single point nanowelding of silver nanowires
Authors: Dai Shuowei , Li Qiang , Liu Guoping , Yang Hangbo , Yang Yuanqing , Zhao Ding , Wang Wei , Qiu Min
Published: March 2016

Nanowelding of nanomaterials opens up an emerging set of applications in transparent conductors, thin-film solar cells, nanocatalysis, cancer therapy, and nanoscale patterning. Single point nanowelding (SPNW) is highly demanded for building complex nanostructures. In this letter, the precise control of SPNW of silver nanowires is explored in depth, where the nanowelding is laser-induced through the plasmonic resonance enhanced photothermal effect. It is shown that the illumination position is a critical factor for the nanowelding process. As an example of performance enhancement, output at wire end can be increased by 65% after welding for a plasmonic nanocoupler. Thus, single point nanowelding technique shows great potentials for high-performance electronic and photonic devices based on nanowires, such as nanoelectronic circuits and plasmonic nanodevices.
Highly reliable and efficient atomic force microscopy based bending test for assessing Young's modulus of one-dimensional nanomaterials
Authors: Gao Yao , Sun Yi-Jing , Zhang Tong-Yi
Published: March 2016

A highly reliable and efficient mechanical characterization technique for one-dimensional nanomaterials was developed based on multi-position bending tests by atomic force microscope (AFM) on top-down fabricated suspended nanowires with double-clamped ends and appropriate theoretical analysis considering residual stress and substrate deformation. The reliability and efficiency of the technique were improved through the avoidance of sample manipulation, high sample comparability, precise experimental control, and more data for mechanics analysis. The AFM-based multi-position bending tests were conducted on gold nanowires with thicknesses of ∼90 nm, widths ranged from 180 nm to 340 nm, and suspension lengths ranged from 3.6 μm to 5.1 μm, showing good testing repeatability and data reliability. The evaluated Young's modulus for gold nanowires was 75.35 ± 6.60 GPa, which had a much smaller deviation compared to that of 72.06 ± 16.21 GPa reported in the literature.
Quantitative measurements of shear displacement using atomic force microscopy
Authors: Wang Wenbo , Sun Ying , Zhao Yonggang , Wu Weida
Published: March 2016

We report a method to quantitatively measure local shear deformation with high sensitivity using atomic force microscopy. The key point is to simultaneously detect both torsional and buckling motions of atomic force microscopy (AFM) cantilevers induced by the lateral piezoelectric response of the sample. This requires the quantitative calibration of torsional and buckling response of AFM. This method is validated by measuring the angular dependence of the in-plane piezoelectric response of a piece of piezoelectric α-quartz. The accurate determination of the amplitude and orientation of the in-plane piezoelectric response, without rotation, would greatly enhance the efficiency of lateral piezoelectric force microscopy.
Hydroxyl radical formation from bacteria-assisted Fenton chemistry at neutral pH under environmentally relevant conditions
Authors: Grossman Jarod N. , Kahan Tara F.
Published: March 2016

Environmental contextReactions in natural waters such as lakes and streams are thought to be extremely slow in the absence of sunlight (e.g. at night). We demonstrate that in the presence of iron, hydrogen peroxide and certain bacteria (all of which are common in natural waters), certain reactions may occur surprisingly quickly. These findings will help us predict the fate of many compounds, including pollutants, in natural waters at night.
AbstractDark Fenton chemistry is an important source of hydroxyl radicals (OH•) in natural waters in the absence of sunlight. Hydroxyl radical production by this process is very slow in many bodies of water, owing to slow reduction and low solubility of FeIII at neutral and near-neutral pH. We have investigated the effects of the iron-reducing bacteria Shewanella oneidensis (SO) on OH• production rates from Fenton chemistry at environmentally relevant hydrogen peroxide (H2O2) and iron concentrations at neutral pH. In the presence of 2.0 × 10–4M H2O2, OH• production rates increased from 1.3 × 10–10 to 2.0 × 10–10Ms–1 in the presence of 7.0 × 106cellsmL–1 SO when iron (at a concentration of 100μM) was in the form of FeII, and from 3.6 × 10–11 to 2.2 × 10–10Ms–1 when iron was in the form of FeIII. This represents rate increases of factors of 1.5 and 6 respectively. We measured OH• production rates at a range of H2O2 concentrations and SO cell densities. Production rates depended linearly on both variables. We also demonstrate that bacteria-assisted Fenton chemistry can result in rapid degradation of aromatic pollutants such as anthracene. Our results suggest that iron-reducing bacteria such as SO may be important contributors to radical formation in dark natural waters.
Effects of different fertilisers on rice resistance to pests and diseases
Authors: Teng Qing , Hu Xue-Feng , Chang Yue-Ya , Luo Fan , Liu Liming , Cheng Chang , Luo Zhi-Qing , Mu Zhen , Yang Min-Yong , Men Dian-Ying , Jiang Yi-Jun
Published: March 2016

A field experiment was conducted in Shanghai in 2013, to study the effects of different fertiliser applications on the occurrence of rice pests and diseases. The experiment included four treatments: a non-fertilised control (CK); rapeseed cake manure (CM) at a low (CML) and a high (CMH) rate; and a synthetic chemical fertiliser (CF). No pesticides were applied within the rice-growing season. The rice plants treated with CF grew tallest, and had higher contents of NH4+-N, NO3–-N, chlorophyll and soluble proteins than those in the other fertiliser treatments and CK. However, the incidence of leaf rollers (Cnaphalocrocis medinalis), stem borers (Chilo suppressalis) and planthoppers on the rice plants treated with CF was significantly higher than in the other fertiliser treatments and CK (P < 0.05). In particular, the incidence of stem borers in the plants treated with CF was about 10 times higher than in the other treatments and CK, and the density of planthopper populations on the plants treated with CF was 1.73, 1.42 and 3.04 times that on plants treated with CMH, CML and CK, respectively. The application of fertilisers increased soil microorganisms, and the effects of rapeseed cake manure on the increase in microorganisms were most significant. Numbers of soil bacteria, fungi and Actinomyces were the highest in soils treated with CMH. Application of rapeseed cake manure also significantly raised the activity of soil dehydrogenase. The CF treatment inhibited dehydrogenase activity but raised urease activity significantly. Average theoretical grain yields in treatments CML, CMH, CF and CK were 7.45 × 103, 8.85 × 103, 7.41 × 103 and 3.70 × 103 kg ha–1, respectively. The application of CF stimulated rice vegetative growth more effectively but finally led to lower grain yield due to higher incidence of pests and diseases.
Characterization of the complex formed by β-glucocerebrosidase and the lysosomal integral membrane protein type-2
Authors: Zunke Friederike , Andresen Lisa , Wesseler Sophia , Groth Johann , Arnold Philipp , Rothaug Michelle , Mazzulli Joseph R. , Krainc Dimitri , Blanz Judith , Saftig Paul , Schwake Michael
Published: March 2016

Significance

Apart from the lysosomal integral membrane protein type-2 (LIMP-2)–dependent trafficking of β-glucocerebrosidase (GC) to lysosomes, little is known about the interaction of LIMP-2 and GC on the molecular level. The structural and biochemical characterization of LIMP-2/GC interaction sites has potential importance for the design of GC-activating compounds. We show that a LIMP-2–derived helical peptide can be used for efficient purification and activation of recombinant and endogenous GC. These results provide a molecular framework for the design of GC activators as potential treatments in Parkinson’s disease and related synucleinopathies.
Representation of spontaneous movement by dopaminergic neurons is cell-type selective and disrupted in parkinsonism
Authors: Dodson Paul D. , Dreyer Jakob K. , Jennings Katie A. , Syed Emilie C. J. , Wade-Martins Richard , Cragg Stephanie J. , Bolam J. Paul , Magill Peter J.
Published: March 2016

Significance

Deciphering the roles of midbrain dopaminergic neurons in the control of movement is critical not only for understanding of normal motor function but also for defining the basis of motor dysfunction in Parkinson’s disease. However the activity of these neurons generally has been considered to be unrelated to movement. Here we demonstrate that dopaminergic neurons signal the onset of spontaneous movement in a cell-type–selective manner and that these signals can be read out in transmitter and receptor activity dynamics in the striatum, one of their principal targets. Importantly, these movement-related signals were lost in a mouse model of Parkinson’s disease. Together, these data suggest that movement-related firing of dopaminergic neurons is important for precise motor control.
Biosynthesis of coral settlement cue tetrabromopyrrole in marine bacteria by a uniquely adapted brominase–thioesterase enzyme pair
Authors: El Gamal Abrahim , Agarwal Vinayak , Diethelm Stefan , Rahman Imran , Schorn Michelle A. , Sneed Jennifer M. , Louie Gordon V. , Whalen Kristen E. , Mincer Tracy J. , Noel Joseph P. , Paul Valerie J. , Moore Bradley S.
Published: March 2016

Significance

The majority of pharmaceuticals are inspired by natural product scaffolds that are functionalized by tailoring enzymes, such as halogenases. The degree of halogenation is an important determinant of natural product bioactivity, yet little is known regarding the molecular basis for the exquisite control exhibited by tailoring halogenases. Known pyrrole halogenases commonly perform up to two halogenations on the pyrrole. Our study of tetrabromopyrrole biosynthesis revealed a uniquely adapted halogenase–thioesterase enzyme pair that catalyzes an unprecedented series of halogenations on a pyrrole. Structural comparison of the pyrrole tetrahalogenase to a pyrrole dihalogenase revealed key residues involved in controlling the degree of halogenation. Our findings provide fundamental insights that might be applied in the rational design of biocatalysts toward directed biosynthesis of new chemicals.
Revealing metallic ink in Herculaneum papyri
Authors: Brun Emmanuel , Cotte Marine , Wright Jonathan , Ruat Marie , Tack Pieter , Vincze Laszlo , Ferrero Claudio , Delattre Daniel , Mocella Vito
Published: March 2016

Significance

The common belief has been that no metal is present in Greco-Roman inks. In this work, we show that lead is present in the ink of two Herculaneum papyrus fragments. The concentration found is very high and not to be explained merely by contamination. The metal found in these fragments deeply modifies our knowledge of Greek and Latin writing in antiquity. Moreover, these concentration values allow the optimization of future computed tomography experiments on still-unrolled Herculaneum scrolls to enable the recovery of texts in the only surviving ancient Greco-Roman library. The possibility of using additional material to trace down ruled lines guiding the scribes' writing along straight lines is also addressed. We demonstrate that no additional material was used for this goal.
Convergence in the temperature response of leaf respiration across biomes and plant functional types
Authors: Heskel Mary A. , O’Sullivan Odhran S. , Reich Peter B. , Tjoelker Mark G. , Weerasinghe Lasantha K. , Penillard Aurore , Egerton John J. G. , Creek Danielle , Bloomfield Keith J. , Xiang Jen , Sinca Felipe , Stangl Zsofia R. , Martinez-de la Torre Alberto , Griffin Kevin L. , Huntingford Chris , Hurry Vaughan , Meir Patrick , Turnbull Matthew H. , Atkin Owen K.
Published: March 2016

Significance

A major concern for terrestrial biosphere models is accounting for the temperature response of leaf respiration at regional/global scales. Most biosphere models incorrectly assume that respiration increases exponentially with rising temperature, with profound effects for predicted ecosystem carbon exchange. Based on a study of 231 species in 7 biomes, we find that the rise in respiration with temperature can be generalized across biomes and plant types, with temperature sensitivity declining as leaves warm. This finding indicates universally conserved controls on the temperature sensitivity of leaf metabolism. Accounting for the temperature function markedly lowers simulated respiration rates in cold biomes, which has important consequences for estimates of carbon storage in vegetation, predicted concentrations of atmospheric carbon dioxide, and future surface temperatures.
Invasive mammal eradication on islands results in substantial conservation gains
Authors: Jones Holly P. , Holmes Nick D. , Butchart Stuart H. M. , Tershy Bernie R. , Kappes Peter J. , Corkery Ilse , Aguirre-Muñoz Alfonso , Armstrong Doug P. , Bonnaud Elsa , Burbidge Andrew A. , Campbell Karl , Courchamp Franck , Cowan Philip E. , Cuthbert Richard J. , Ebbert Steve , Genovesi Piero , Howald Gregg R. , Keitt Bradford S. , Kress Stephen W. , Miskelly Colin M. , Oppel Steffen , Poncet Sally , Rauzon Mark J. , Rocamora Gérard , Russell James C. , Samaniego-Herrera Araceli , Seddon Philip J. , Spatz Dena R. , Towns David R. , Croll Donald A.
Published: March 2016

Significance

Global conservation actions to prevent or slow extinctions and protect biodiversity are costly. However, few conservation actions have been evaluated for their efficacy globally, hampering the prioritization of conservation actions. Islands are key areas for biodiversity conservation because they are home to more than 15% of terrestrial species and more than one-third of critically endangered species; nearly two-thirds of recent extinctions were of island species. This research quantifies the benefits to native island fauna of removing invasive mammals from islands. Our results highlight the importance of this conservation measure for protecting the world's most threatened species.
Cell-specific localization of alkaloids in
Catharanthus roseus
stem tissue measured with Imaging MS and Single-cell MS
Authors: Yamamoto Kotaro , Takahashi Katsutoshi , Mizuno Hajime , Anegawa Aya , Ishizaki Kimitsune , Fukaki Hidehiro , Ohnishi Miwa , Yamazaki Mami , Masujima Tsutomu , Mimura Tetsuro
Published: March 2016

Significance

Terpenoid indole alkaloids are known to be valuable bioactive compounds. In situ RNA hybridization of gene expression of the terpenoid indole alkaloid (TIA) synthetic enzymes has suggested that the TIA metabolic pathway in
Catharanthus roseus
stem tissue involves the successive metabolic flow of four types of cells: internal phloem-associated parenchyma, epidermal, idioblast, and laticifer cells. It has never been directly determined in which of these cells these TIA intermediates are localized. The present study showed, using both Imaging mass spectrometry (MS) and Single-cell MS, that many kinds of TIA intermediates, including catharanthine and serpentine, were accumulated in idioblast and laticifer cells. The developed methods should prove useful for studying other aspects of secondary metabolism in plants.
Photochemical reaction cycle transitions during anion channelrhodopsin gating
Authors: Sineshchekov Oleg A. , Li Hai , Govorunova Elena G. , Spudich John L.
Published: March 2016

Significance

The discovery of natural anion channelrhodopsins (ACRs) opens possibilities for rapid and efficient inhibition of neuronal firing by hyperpolarization, but molecular mechanisms of these proteins’ function remain elusive. We studied spectral properties and photochemical conversions of purified wild-type and mutant ACRs to probe the coupling between chromophore photoexcitation and alteration of protein conformation leading to electrical conductance in the membrane. Our results show that not only the selectivity filter, but also the structural basis of channel gating in the cryptophyte ACRs differs from that in cation channelrhodopsins (CCRs) from chlorophyte algae used to depolarize the membrane. The knowledge of structure–function relationships in ACRs will benefit molecular engineering to improve their performance as tools for optogenetic research and therapies.
Individual differences in frontolimbic circuitry and anxiety emerge with adolescent changes in endocannabinoid signaling across species
Authors: Gee Dylan G. , Fetcho Robert N. , Jing Deqiang , Li Anfei , Glatt Charles E. , Drysdale Andrew T. , Cohen Alexandra O. , Dellarco Danielle V. , Yang Rui R. , Dale Anders M. , Jernigan Terry L. , Lee Francis S. , Casey B.J. ,   the PING Consortium, Jernigan Terry L. , San Diego UC ,   Co-PI of PING, Core PI, McCabe Connor , San Diego UC , Chang Linda , Hawaii U ,   Co-PI of PING, Core PI, Akshoomoff Natacha , San Diego UC , Newman Erik , San Diego UC , Dale Anders M. , San Diego UC ,   Co-PI of PING, Core PI, Core MRI Acquisition , Ernst Thomas , Hawaii U ,   Co-PI of PING, Core Co-PI, Dale Anders M. , San Diego UC ,   Core Co-PI, Van Zijl Peter ,   KKI, Kuperman Joshua , San Diego UC , Murray Sarah ,   Scripps Translational Science Institute, Co-PI of PING, Core PI, Bloss Cinnamon ,   Scripps Translational Science Institute, Schork Nicholas J. ,   Scripps Translational Science Institute, Appelbaum Mark , San Diego UC , Gamst Anthony , San Diego UC , Thompson Wesley , San Diego UC , Bartsch Hauke , San Diego UC , Jernigan Terry L. , Dale Anders M. , Akshoomoff Natacha , Chang Linda , Ernst Thomas , Keating Brian , Amaral David , Sowell Elizabeth , Kaufmann Walter , Van Zijl Peter , Mostofsky Stewart , Casey B.J. , Ruberry Erika J. , Powers Alisa , Rosen Bruce , Kenet Tal , Frazier Jean , Kennedy David , University Yale , Gruen Jeffrey
Published: March 2016

Significance

Anxiety disorders peak during adolescence, a developmental period that is marked by dynamic changes in gene expression, frontolimbic circuitry, and endocannabinoid signaling. This cross-species study identifies parallel gene by development interactions across humans and a knock-in mouse model of the same fatty acid amide hydrolase (FAAH) polymorphism. The impact of FAAH genetic variation on frontolimbic circuitry and anxiety in mice and humans emerges during adolescence as anandamide levels decrease but not before. These findings have important implications for the identification of risk for disease and precise targeting of treatments to the biological state of the developing brain as a function of developmental changes in gene expression and neural circuit maturation.
Behavioral contagion during learning about another agent’s risk-preferences acts on the neural representation of decision-risk
Authors: Suzuki Shinsuke , Jensen Emily L. S. , Bossaerts Peter , O’Doherty John P.
Published: March 2016

Significance

Why do we on some occasions engage in risky behavior but not on other occasions? Here, we explore the neural mechanisms of one possible account: a contagion effect. Using neuroimaging combined with computational modeling, we show that if we observe others behaving in a risk-seeking/risk-averse fashion, we become in turn more/less prone to risky behavior, and the behavioral shift is specifically implemented via neural processing of risk in a brain region, caudate nucleus. We further show that functional connectivity between the caudate and the dorsolateral prefrontal cortex, a region implicated in learning about others’ risk-attitude, is associated with susceptibility to the contagion effect, providing an account for how our own behavior can be influenced through observing other agents.
Epigenome confrontation triggers immediate reprogramming of DNA methylation and transposon silencing inArabidopsis thalianaF1 epihybrids
Authors: Rigal Mélanie , Becker Claude , Pélissier Thierry , Pogorelcnik Romain , Devos Jane , Ikeda Yoko , Weigel Detlef , Mathieu Olivier
Published: March 2016

Significance

Similar to changes in DNA sequence, induced or naturally occurring variation in cytosine methylation can impact gene expression. How distinct methylation states of genes and transposons, called epialleles, emerge is not well understood. Here, we report that combining identical genomes with drastically different DNA methylation patterns in the same individual results in an epigenomic shock that is characterized by widespread changes in DNA methylation and gene expression. Many novel epialleles not found in the parents are formed at genes whereas transposons often experience decreased DNA methylation associated with transcriptional activation. Our work provides a scenario for the rapid and broad-scale emergence of epigenetic variation and may have implications for transposon dynamics within populations.
PGE2 induced in and released by dying cells functions as an inhibitory DAMP
Authors: Hangai Sho , Ao Tomoka , Kimura Yoshitaka , Matsuki Kosuke , Kawamura Takeshi , Negishi Hideo , Nishio Junko , Kodama Tatsuhiko , Taniguchi Tadatsugu , Yanai Hideyuki
Published: March 2016

Significance

Inflammation is an integral part of the immune responses for the protection of the host to harmful stimuli. However, because inflammation can also underlie the initiation and/or exacerbation of a variety of diseases, it must be tightly regulated. Upon cell death, self-derived molecules, called damage-associated molecular patterns (DAMPs), are released to activate inflammatory responses. It has been unknown whether inhibitory molecules are also released to balance the magnitude of the inflammatory responses. In this study, biochemical and in vivo data demonstrate that prostaglandin E2 is a DAMP that negatively regulates cell death-induced inflammatory responses. These findings reveal an unprecedented facet in the regulation of inflammation via the combined activity of activating and inhibiting DAMPs, which may have clinical implications.
Discovery of unfixed endogenous retrovirus insertions in diverse human populations
Authors: Wildschutte Julia Halo , Williams Zachary H. , Montesion Meagan , Subramanian Ravi P. , Kidd Jeffrey M. , Coffin John M.
Published: March 2016

Significance

The human endogenous retrovirus (HERV) group HERV-K contains nearly intact and insertionally polymorphic integrations among humans, many of which code for viral proteins. Expression of such HERV-K proviruses occurs in tissues associated with cancers and autoimmune diseases, and in HIV-infected individuals, suggesting possible pathogenic effects. Proper characterization of these elements necessitates the discrimination of individual HERV-K loci; such studies are hampered by our incomplete catalog of HERV-K insertions, motivating the identification of additional HERV-K copies in humans. By examining >2,500 sequenced genomes, we have discovered 19 previously unidentified HERV-K insertions, including an intact provirus without apparent substitutions that would alter viral function, only the second such provirus described. Our results provide a basis for future studies of HERV evolution and implication for disease.
CRLX101 nanoparticles localize in human tumors and not in adjacent, nonneoplastic tissue after intravenous dosing
Authors: Clark Andrew J. , Wiley Devin T. , Zuckerman Jonathan E. , Webster Paul , Chao Joseph , Lin James , Yen Yun , Davis Mark E.
Published: March 2016

Significance

Nanoparticle-based therapeutics rely on the enhanced permeability and retention effect to localize in solid tumors and not healthy tissue. These phenomena are rationalized from animal models of human disease. Since these models poorly represent human tumors, there is a need to obtain information from humans to better understand how nanoparticle-based therapeutics perform in humans. Here, we collected tumor and nonneoplastic tissue biopsies from cancer patients who have been administered CRLX101 and show that the intact nanoparticles localize in human tumors and not in adjacent tissues. Sufficient concentrations reach the tumors to cause down-regulation of topoisomerase I and carbonic anhydrase IX. These results will aid in better understanding how nanoparticle therapeutics function in humans and how to better design future therapeutics.