bluuebunny/crossref_metadata_2025 huggingface dataset:
Piezoelectric analysis of reactively grown PbTiO3
Authors: Dunn Steve , Harada Scott
Published: December 2009

We have investigated a technique that is a combination of sputtering, evaporation, and annealing for the production of thin film and nanostructured PbTiO3 that we show to be piezoelectric via piezoresponse force microscopy (PFM). The synthesis technique involved depositing lead, via thermal evaporation, onto the surface of a variety of substrates that had Ti as the uppermost layer, followed by conventional or rapid thermal annealing in air to form PbTiO3. By careful control of the deposition time, samples ranging from discrete nanoislands to thin films could be produced. The nanoisland samples while exhibiting a piezoelectric response displayed little or no domain structure even with grains as large as 100 nm in diameter. However, we see a domain pattern in the thin film samples. We show that there are difficulties in poling PbTiO3 thin films using PFM due to the high coercive field required and the number of shorts through the thin films.
Light transmission through metallic two-dimensional arrays of compound coaxial structures with central and annular apertures: A charge oscillation picture
Authors: He Meng-Dong , Liu Jian-Qiang , Chen Xiaoshuang
Published: December 2009

We investigate the transmission characteristics of metallic film perforated with a two-dimensional array of compound coaxial structures with central and annular apertures by using a charge oscillation picture. It is found that the transmission peak mainly resulted from the resonance of the central apertures (annular apertures) in such structure exhibits changes in position and intensity in comparison with that in the corresponding structure of aperture array (annular-aperture array) due to the effect of the oscillating charges appearing near the annular apertures (central apertures) on the transmission peak. The transmission peak corresponding to the resonance of the central apertures (annular apertures) can be tuned by changing not only the geometrical parameters of the central apertures (annular apertures) but also the sizes of the annular apertures (central apertures). Our results may be utilized to control the electromagnetic wave in subwavelength optics.
Strong room-temperature ferromagnetism in Cu-implanted nonpolar GaN films
Authors: Sun Lili , Yan Fawang , Zhang Huixiao , Wang Junxi , Zeng Yiping , Wang Guohong , Li Jinmin
Published: December 2009

Diluted magnetic nonpolar GaN:Cu films with ferromagnetic properties up to 380 K have been fabricated by implantation of Cu ions into nonpolar a-plane GaN films and a subsequent thermal annealing process. The nonpolar GaN:Cu films exhibit a strong saturation magnetization about 1.54 μB/Cu atom, while polar GaN:Cu films can only show a weak saturation magnetization of 0.36 μB/Cu atom. Moreover, according to the x-ray photoelectron spectroscopy results, the stronger ferromagnetism of nonpolar GaN:Cu films may be resulted from the higher Cu incorporation efficiency in nonpolar GaN films.
Analytical study of the superstable 3-cycle in the logistic map
Authors: Lee M. Howard
Published: December 2009

In the logistic map, the simplest of stable odd-numbered cycles is a 3-cycle. It comes into existence after the stable 2k cycles cease to exist. The 3-cycle is thus important as a route to chaos. In 1977 Guckenheimer et al. [J. Math. Biol. 4, 101 (1977)] first estimated the value of the control parameter a at which it can be superstable. It implies that a stable 3-cycle can be formed and deformed at some values of a straddling that of the superstable 3-cycle. In this work we present an exact value of a for the superstable 3-cycle by reducing a polynomial of degree 7 to that of 3. The relevance of this work to Sharkovskii’s theorem is also discussed.
An analysis of domain reorientation in PLZT ceramics byin situRaman spectroscopy
Authors: Yang Feng-Juan , Cheng Xuan , Zhou Zhi-Dong , Zhang Ying
Published: December 2009

An in situ Raman spectroscopy in a parallel y(z,z)y configuration was employed to investigate the domain reorientation of unpoled lanthanum-doped lead zirconate titanate (PLZT) ceramics under the dc electric field of 2000 V/mm. It was found that the relative intensity ratio IE(2TO)/IE(3TO+2LO)+B1 of Raman optical modes varied periodically by 180° with the polarized direction of the laser beam. The maximum change in the intensity ratio may be correlated with the extent of the polarization within the PLZT ceramics. Upon taking the effects of the long-range electric fields associated with the polar vibrations into consideration, a formula is developed to describe the variations in the intensity ratio IE(2TO)/IE(3TO+2LO)+B1, and the average orientation within the examined grain during the application of electric field is further evaluated to be ∼33.8°.
Strain distributions and interband transitions of CdxZn1−xTe/ZnTe asymmetric double quantum dots with different degree of coupling
Authors: You J. H. , Woo J. T. , Kim T. W. , Yoo K. H. , Lee H. S. , Park H. L.
Published: December 2009

Strain distributions and interband transitions of CdxZn1−xTe/ZnTe asymmetric double quantum dots (DQDs) with different degree of coupling were calculated by using a three-dimensional finite difference method (FDM) taking into account strain and nonparabolicity effects. Bird’s-eye views of the truncated contour plots of the ground state wave functions at the conduction band of the Cd0.6Zn0.4Te/ZnTe DQDs showed the transition behavior from the coupling to the decoupling behaviors with increasing ZnTe spacer layer thickness. The interband transition energies from the ground electronic subband to the ground heavy-hole band (E1-HH1) in the CdxZn1−xTe/ZnTe DQDs, as determined from the FDM calculations, were in reasonable agreement with the experimental peaks of the temperature-dependent photoluminescence spectra corresponding to the (E1-HH1) interband transition energies in the temperature range from 32 to 130 K.
The Fourier transform microwave spectrum of the arsenic dicarbide radical (CCAs: X̃Π1∕22) and its C13 isotopologues
Authors: Sun M. , Clouthier D. J. , Ziurys L. M.
Published: December 2009

The pure rotational spectrum of the CCAs radical in its ground electronic and spin state, X̃Π1∕22, has been measured using Fourier transform microwave techniques in the frequency range of 12–40GHz. This species was created in a supersonic expansion from a reaction mixture of AsCl3 and C2H2 or CH4 diluted in high pressure argon, using a pulsed nozzle containing a dc discharge source. Three rotational transitions were measured for the main isotopologue, C12C12As, in the Ω=12 ladder; both lambda-doubling and arsenic (I=3∕2) hyperfine interactions were observed in these spectra. In addition, two to four rotational transitions were recorded for the C13C13As, C13C12As, and C12C13As species. In these three isotopologues, hyperfine splittings were also resolved arising from the C13 nuclei (I=12), creating complex spectral patterns. The CCAs spectra were analyzed with a case (a) Hamiltonian, and effective rotational, lambda-doubling, and arsenic and carbon-13 hyperfine constants were determined for the Ω=12 ladder. From the effective rotational constants of the four isotopologues, an rm(1) structure has been derived with rC–C=1.287Å and rC–As=1.745Å. These bond lengths indicate that the predominant structure for arsenic dicarbide is CCAs⋅, with some contributing CC and CAs triple bond characters. The hyperfine constants established in this work indicate that about 2∕3 of the unpaired electron density lies on the arsenic atom, with the remaining percentage on the terminal carbon. The value of the arsenic quadrupole coupling constant (eqQ=−202MHz) suggests that the As–C bond has a mixture of covalent and ionic characters, consistent with theoretical predictions that both π backbonding and electron transfer play a role in creating a linear, as opposed to a cyclic, structure for certain heteroatom dicarbides.
Prolongation structures and exact solutions of K(m,n) equations
Authors: Wang Deng-Shan , Lou S. Y.
Published: December 2009

In this paper, Rosenau and Hyman’s [Phys. Rev. Lett. 70, 564 (1993)] K(m,n) equations are studied by prolongation technique. It is proved that K(m,n) equations are Lax integrable only for certain special parameters (α,m,n). The nontrivial prolongation structures and Lax pairs for the integrable cases are given. Finally, as an example, the one and two soliton solutions for the K(−12,−12) equation are derived by means of inverse scattering method.
Nucleation of tetrahedral solids: A molecular dynamics study of supercooled liquid silicon
Authors: Li Tianshu , Donadio Davide , Galli Giulia
Published: December 2009

The early stages of crystallization of tetrahedral systems remain largely unknown, due to experimental limitations in spatial and temporal resolutions. Computer simulations, when combined with advanced sampling techniques, can provide valuable details about nucleation at the atomistic level. Here we describe a computational approach that combines the forward flux sampling method with molecular dynamics, and we apply it to the study of nucleation in supercooled liquid silicon. We investigated different supercooling temperatures, namely, 0.79, 0.86, and 0.95 of the equilibrium melting point Tm. Our results show the calculated nucleation rates decrease from 5.52±1.75×1028 to 4.77±3.26×1011 m−3 s−1 at 0.79 and 0.86 Tm, respectively. A comparison between simulation results and those of classical nucleation theory shows that the free energy of the liquid solid interface γls inferred from our computations differ by about 28% from that obtained for bulk liquid solid interfaces. However the computed values of γls appear to be rather insensitive to supercooling temperature variations. Our simulations also yield atomistic details of the nucleation process, including the atomic structure of critical nuclei and lifetime distributions of subcritical nuclei.
Fracture of nanoscale copper films on elastomer substrates
Authors: Begley Matthew R. , Scott Orion N. , Utz Marcel , Bart-Smith Hilary
Published: December 2009

This letter describes the evolution of crack spacing in copper films (bonded to elastomer substrates) as a function of applied strain. Tension tests were conducted on cast poly(dimethylsiloxane) substrates coated with sputtered copper films with 200–600 nm thickness. Optical microscopy was used to measure the spacings between parallel cracks (normal to the tension direction) at various levels of applied strain in the range of 0.01%–10%. The measured relationships between applied strain and crack spacing are predicted by micromechanical models of behavior between cracks; the experiments indicate Gc∼400–600 J/m2 with an implied defect spacing of ∼100–600 μm. These values are consistent with the theoretical work that is dissipated during necking instabilities during plastic deformation.
Tunable localization and oscillation of coupled plasmon waves in graded plasmonic chains
Authors: Zheng M. J. , Xiao J. J. , Yu K. W.
Published: December 2009

The localization (confinement) of coupled plasmon modes, named as gradons, has been studied in metal nanoparticle chains immersed in a graded dielectric host. We exploited the time evolution of various initial wavepackets formed by the linear combination of the coupled modes. We found an important interplay between the localization of plasmonic gradons and the oscillation in such graded plasmonic chains. Unlike in optical superlattices, gradient cannot always lead to Bloch oscillations, which can only occur for wavepackets consisting of particular types of gradons. Moreover, the wavepackets undergo different forms of oscillations. The correspondence can be applied to design a variety of optical devices by steering among various oscillations.
Structural properties of wurtzitelike ScGaN films grown by NH3-molecular beam epitaxy
Authors: Moram M. A. , Zhang Y. , Joyce T. B. , Holec D. , Chalker P. R. , Mayrhofer P. H. , Kappers M. J. , Humphreys C. J.
Published: December 2009

Scandium gallium nitride (ScxGa1−xN) alloy films with low Sc concentrations (up to approximately x=0.08) were grown using molecular beam epitaxy with NH3 as a reactive N source, on GaN films that were grown on sapphire using metalorganic vapor phase epitaxy (MOVPE). High-resolution x-ray diffraction and transmission electron microscopy revealed that both the c and the a lattice parameters increased with increasing Sc concentration, as predicted for a wurtzite-structure alloy. As the Sc content increased, the relaxation of the compressive stress in the ScxGa1−xN films occurred mainly via the introduction of additional a-type dislocations, but neither stacking faults nor significant compositional segregation was observed at any composition. A dewetting effect (which increased with increasing Sc content) was observed in MOVPE-grown GaN deposited on top of the ScxGa1−xN films, but the ScxGa1−xN remained compositionally and structurally stable under GaN growth conditions.
Critical behavior of the spinel CdCr2S4
Authors: Luo X. , Yang Z. R. , Sun Y. P. , Zhu X. B. , Song W. H. , Dai J. M.
Published: December 2009

We present our investigation on the critical behavior of the spinel compound CdCr2S4 via the ac susceptibility and dc magnetization measurements. The analysis of ac susceptibility in terms of scaling behavior yields exponent values of δ=5.38±0.01, γ+β=1.77±0.03 and γ=1.44±0.02. Both δ and γ are slightly larger than that predicted by Heisenberg model. Detailed analyses of the inverse of the susceptibility and the electron spin resonance experiment reveal that the existence of correlated magnetic polarons has a key impact on the ferromagnetism of the spinel CdCr2S4. The abnormal critical exponent value of δ of CdCr2S4 may be attributed to the formation of the correlated magnetic polarons and abnormal spin-phonon coupling.
Robustness of computational time reversal imaging in media with elastic constant uncertainties
Authors: Scalerandi M. , Griffa M. , Johnson P. A.
Published: December 2009

In order to image a source or a scatterer embedded in a three dimensional solid, acoustic/elastic wave data from an actual experiment are time reversed and backpropagated through a numerical model of the medium. The model makes use of estimates for the elastic constants of the laboratory solid. These estimates may not be very precise, for example, due to experimental uncertainties. Poor characterization of the medium leads to the degradation of the time reversal focus, therefore, to poor medium imaging. In this work, we report on the results of investigating the time reversal focus degradation as the estimates depart from the real values. Very small deviations from the medium’s actual elastic constants degrade the time reversal focus dramatically. However, decreasing the total duration of the signals used for time reversal can attenuate the degradation in some cases. We propose a new method to compensate for the deviations of the model medium’s elastic constants from the actual values. Finally, we explore the effects of scatterers that may exist in the laboratory medium, but are not included in the model medium, and show that their presence does not produce significant effects on the time reversal focus.
The quality factor of a superconducting rf resonator in a magnetic field
Authors: Ulmer S. , Kracke H. , Blaum K. , Kreim S. , Mooser A. , Quint W. , Rodegheri C. C. , Walz J.
Published: December 2009

The quality factor of a superconducting NbTi resonator at 1.6 MHz in a magnetic field up to 1.2 T as well as its temperature dependence is investigated. A hysteresis effect in the superconducting surface resistance as a function of the magnetic field is observed. An unloaded Q-value of the resonator of 40 500 is achieved at 3.9 K. It is shown that this Q-value is limited by dielectric losses in the FORMVAR insulation of the coils wire. The details of the Q-value optimization are discussed. In the temperature dependence of the Q-value a steep decrease is observed above T≈7.5 K. Finally, the implications of these measurements for real trap experiments are discussed in detail.
Organic vapor phase deposition for the growth of large area organic electronic devices
Authors: Lunt Richard R. , Lassiter Brian E. , Benziger Jay B. , Forrest Stephen R.
Published: December 2009

We demonstrate that material utilization efficiencies of 50% and deposition nonuniformities ≤2.5% are achievable over substrate diameters of 200 mm using a simplified, organic vapor phase deposition (OVPD) system. The OVPD system is used to demonstrate doped electrophosphorescent organic light emitting diodes whose performance is comparable to those grown by vacuum thermal evaporation. Through continuum modeling, we demonstrate that analogous systems whose chamber dimensions are comparable to the substrate width are scalable to substrate sizes of at least 1500×1800 mm2 with deposition nonuniformities between 1.5% and 2.5%. These results indicate that OVPD is useful in the large area deposition of displays, lighting, and other organic electronic devices.
Optical tweezer for probing erythrocyte membrane deformability
Authors: Khan Manas , Soni Harsh , Sood A. K.
Published: December 2009

We report that the average rotation speed of optically trapped crenated erythrocytes is direct signature of their membrane deformability. When placed in hypertonic buffer, discocytic erythrocytes are subjected to crenation. The deformation of cells brings in chirality and asymmetry in shape that makes them rotate under the scattering force of a linearly polarized optical trap. A change in the deformability of the erythrocytes, due to any internal or environmental factor, affects the rotation speed of the trapped crenated cells. Here we show how the increment in erythrocyte membrane rigidity with adsorption of Ca++ ions can be exhibited through this approach.
Quantum-dot laser with a metal-coated waveguide under continuous-wave operation at room temperature
Authors: Lu Chien-Yao , Chang Shu-Wei , Yang Shang-Hua , Chuang Shun Lien
Published: December 2009

We fabricated and characterized Fabry–Pérot quantum-dot lasers with metal-coated waveguides. Lasing action at room temperature under continuous-wave operation was observed, contrary to the belief that metal is too lossy to serve as the waveguide material at optical frequencies. We extracted the optical gain and group index from the amplified spontaneous emission spectra. A high group index of about 4.2 has been observed from these metal-coated devices, which is much larger than a value of 3.2 measured from an uncoated quantum-dot laser. It is believed that the metal coating contributes to the high group index in these devices.
Energy- and density-dependent dynamics of photoexcited carriers in InN films
Authors: Fukunaga K. , Hashimoto M. , Kunugita H. , Kamimura J. , Kikuchi A. , Kishino K. , Ema K.
Published: December 2009

Fast and slow photocarrier dynamics in indium nitride films have been investigated using femtosecond transient measurements at room temperature. The behavior of the decay dynamics is found to be strongly dependent on the excitation energy and the background carrier density. We have found that the slow decay component disappears under optimized conditions due to equilibrium between band filling and bandgap renormalization effects.
High magnetic and thermal stability of nanopatterned [Co/Pd] based pseudo spin-valves with perpendicular anisotropy for 1 Gb magnetic random access memory applications
Authors: Thiyagarajah Naganivetha , Joo Ho Wan , Bae Seongtae
Published: December 2009

Nanopatterned [Co/Pd] based pseudo spin-valves (PSV) with perpendicular anisotropy exhibited high magnetic and thermal stabilities suitable for 1 Gb magnetic random access memory applications. Magnetic force microscopy images clearly demonstrated that the nanopatterned [Co/Pd] based PSVs down to 75×75 nm2 show a single domain configuration and a coherent magnetic reversal behavior. Furthermore, the nanopatterned [Co/Pd] based PSV with 90×90 nm2 device size showed stable magnetoresistance performance and switching characteristics. The high magnetic anisotropy and the large exchange energy of [Co/Pd] based PSV with perpendicular anisotropy are thought to be the main physical reasons for the technical promises.
Buffer layer-enhanced magnetic field effect in manganite-based heterojunctions
Authors: Lü W. M. , Sun J. R. , Chen Y. Z. , Shang D. S. , Shen B. G.
Published: December 2009

Influence of magnetic field on the rectifying property of the La0.67Ca0.33MnO3/LaMnO3/SrTiO3:0.05 wt %Nb heterojunctions has been studied. In addition to an enhanced magnetic response of the current-voltage characteristics, a field-induced increase in junction resistance, which is an effect different from that in the junctions without the LaMnO3 layer, is observed. The positive magnetoresistance is further found to show a systematic variation with the thickness of the LaMnO3 layer (t), growing rapidly with the increase of layer thickness and getting a maximum of ∼91% at t=4 nm (T=50 K and ΔH=5 T). Analysis of the current-voltage and capacitance-voltage characteristics indicates a field-induced growth of interfacial barrier, which is responsible for the abnormal effect observed here.
Dynamic behaviors of controllably buckled thin films
Authors: Wang Yong , Feng Xue
Published: December 2009

The controlled buckling of thin films is essential in the stretchable and curvilinear electronics. Through the rigorous governing equations accounting for geometric nonlinearity, dynamic behaviors of buckled thin films, which serve as interconnects in curvilinear electronics, are investigated in detail. The surface effects from surface elasticity and residual surface stress are taken into account due to the thin films thickness at small scale, and the effects of surface properties on dynamic behaviors are obtained. The results will guide the design of interconnects to avoid resonance in complicated noise environment.
Optically active defects in an InAsP/InP quantum well monolithically grown on SrTiO3(001)
Authors: Cheng J. , Aviles T. , El Akra A. , Bru-Chevallier C. , Largeau L. , Patriarche G. , Regreny P. , Benamrouche A. , Robach Y. , Hollinger G. , Saint-Girons G.
Published: December 2009

The optical properties of an InAsP/InP quantum well grown on a SrTiO3(001) substrate are analyzed. At 13 K, the photoluminescence yield of the well is comparable to that of a reference well grown on an InP substrate. Increasing the temperature leads to the activation of nonradiative mechanisms for the sample grown on SrTiO3. The main nonradiative channel is related to the thermal excitation of the holes to the first heavy hole excited state, followed by the nonradiative recombination of the carriers on twins and/or domain boundaries, in the immediate vicinity of the well.
Selectively patterned highly conductive poly(3,4-ethylenedioxythiophene)-tosylate electrodes for high performance organic field-effect transistors
Authors: Lim Jung Ah , Park Song Hee , Baek Ji Hye , Ko Young Dong , Lee Hwa Sung , Cho Kilwon , Lee Jun Young , Lee Dong Ryeol , Cho Jeong Ho
Published: December 2009

We have improved the performance of pentacene field-effect transistors by using highly conductive poly(3,4-ethylenedioxythiophene)-tosylate (PEDOT-Tos) source-drain electrodes (∼103 S/cm) formed by a simple solution-based process. A high field-effect mobility of 0.25 cm2/Vs and an ON/OFF current ratio of 107 were obtained in pentacene-based bottom contact organic field-effect transistors (OFETs), which constitutes an improvement over OFETs based on Au and PEDOT:PSS electrodes. Two-dimensional grazing incidence x-ray diffraction and ultraviolet photoemission spectroscopy results confirmed that the crystalline properties of the pentacene film and the hole injection from the PEDOT-Tos electrode to the pentacene layer are more efficient than those from Au and PEDOT:PSS electrodes.
Low temperature x-ray diffraction study of the phase transitions in Sr1-xCaxTiO3 (x=0.02,0.04): Evidence for ferrielectric ordering
Authors: Mishra Sanjay Kumar , Pandey Dhananjai
Published: December 2009

X-ray diffraction studies on Sr1-x Cax TiO3 in the temperature range 12 to 300 K reveal cubic to tetragonal (I4/mcm) antiferrodistortive and tetragonal to orthorhombic (Ic2m) polar phase transitions at ∼170 and 225, 32, 34 K, respectively, for x=0.02 and 0.04. It is shown that the polarization in the orthorhombic phase is along the ⟨110⟩ pseudocubic direction, in agreement with the experimentally reported easy polarization direction by Bednorz and Muller. However, in disagreement with them the moments are found to be ferrielectrically coupled in the neighboring (001) planes that is responsible for the anomalously low values of the spontaneous polarization in the polar phase.
Random laser action in dielectric-metal-dielectric surface plasmon waveguides
Authors: Kumar Ashwani , Yu S. F. , Li X. F.
Published: December 2009

A dielectric-metal-dielectric (DMD) surface plasmon (SP) waveguide, in which the top and bottom dielectric layers are incorporated with scatters and optical gain, respectively, was realized to support random lasing action. For the DMD waveguide under 532 nm optical excitation, sharp peaks at around 590 nm were observed from the edge of the top dielectric layer. Furthermore, the number of sharp peaks increases with the pump intensity. The dependence of lasing threshold on the excitation area also agrees with the random laser theory. Hence, it is verified that the SP waves, which supported inside the DMD waveguide, exhibit random lasing action.
InGaN multiquantum well structure with a reduced internal electric field and carrier decay process by tunneling
Authors: Park Y. M. , Son J. K. , Chung H. J. , Sone C. , Park Y.
Published: December 2009

An InGaN/InGaN multiquantum well (MQW) structure with a reduced internal electric field is grown, and compared with a conventional InGaN/GaN MQW structure. Time-integrated and time-resolved photoluminescence (PL) are measured as a function of an external bias voltage. The flatband condition, in which the external bias voltage completely compensates the internal electric field, is found by a measurement of PL peak energy as a function of bias voltage. From the measurement of the integrated PL intensity and the PL lifetime, we observe that tunneling has an important role in the carrier decay process of the biased MQW structure. Using the flatband condition, the internal electric field is calculated to be 1.75 and 2.15 MV/cm for InGaN/InGaN and InGaN/GaN structures, respectively.
Predicting soil organic carbon percentage from loss-on-ignition using Bayesian Model Averaging
Authors: Leon Ai , Gonzalez Roberto Leon
Published: December 2009

A shortage of data for percentage of organic carbon (C%) makes calculation of soil profile carbon storage difficult. Loss on ignition (LOI) data, which are cheap to obtain and often readily available, can be used to estimate organic C%. This paper simultaneously considers several predictors of organic C%: LOI, parent material, drainage status, type of soil horizon, clay content, and pH. In order to model appropriately the existence of multiple hypotheses and the consequent model uncertainty, a Bayesian Model Averaging (BMA) approach was used. BMA considers all models that result from all possible combinations of explanatory variables. Based on a BMA approach and Scottish Soil Survey data, it was found that the most important factors to predict organic C% were LOI, clay content, a dummy for Countesswells Association (till derived from granite), and a dummy for B horizon soils. The validation analysis showed that prediction accuracy for organic C% was better with the BMA approach than with an ordinary least-squares approach that includes no other predictors apart from LOI (i.e. 22% reduction in horizons A, Ap, and C).
Drying temperature effects on bulk density and carbon density determination in soils of northern New South Wales
Authors: Wilson Brian , Ghosh Subhadip , Barnes Phoebe , Kristiansen Paul
Published: December 2009

There is a widespread and growing need for information relating to soil condition and changes in response to land management pressures. To provide the information needed to quantify land management effects on soil condition, monitoring systems are now being put in place and these programs will generate large numbers of samples. Streamlined procedures for the analysis of large sample numbers are therefore required. Bulk density (BD) is considered to be one of several key indicators for measuring soil physical condition, and is also required to estimate soil carbon density. The standard analytical technique for BD requires drying the soil at 105°C but this procedure creates several logistical and analytical problems. Our initial objective was to derive correction factors between drying temperatures to allow for rapid, low-temperature estimation of BD on large sample numbers. Soil samples were collected from 3 contrasting soil types (basalt, granite, and meta-sediments) in 4 land uses (cultivation, sown pasture, native pasture, woodland) in northern New South Wales to test the effect of soil drying temperature on BD determination. Cores were divided into 4 depths (0–0.05, 0.050–0.10, 0.10–0.20, 0.20–0.30 m), and oven-dried at 40, 70, and 105°C. Drying temperature had no significant effect on BD but the effects of soil type, depth, and land use were significant, varying according to expectations based on previous studies, i.e. higher BD in granite-derived soils and lower in basalt-derived soils, increased BD with depth, and increasing BD with increasing management intensity. These results indicate that lower drying temperatures (40°C) were adequate for the efficient determination of BD especially where analysis of other soil properties from the same sample is required. However, before this approach is applied more widely, further calibration of BD and drying temperature should be undertaken across a wider range of soils, especially on clay-rich soils.
Infiltration and erosion in soils treated with dry PAM, of two molecular weights, and phosphogypsum
Authors: Mamedov A. I. , Shainberg I. , Wagner L. E. , Warrington D. N. , Levy G. J.
Published: December 2009

Soil surface application of dissolved linear polyacrylamide (PAM) of high molecular weight (MW) can mitigate seal formation, runoff, and erosion, especially when added with a source of electrolytes (e.g. gypsum). Practical difficulties associated with PAM solution application prohibited commercial use of PAM in dryland farming. An alternative practice of spreading dry granular PAM with high MW on the soil surface has been ineffective in reducing runoff while effectively reducing erosion. The objective of this study was to investigate the mechanism by which granular PAM (20 kg/ha), with moderate (2 × 105 Da) or high (1.2 × 107 Da) MW, mixed with phosphogypsum (PG) (4 Mg/ha) affects infiltration rate, runoff, and erosion. Five smectitic soils, treated with PAM and PG, were exposed to simulated rainfall of deionised water in the laboratory. Both dry PAMs, mixed with PG, increased final infiltration rate (3–5 times) and reduced erosion (2–4 times) relative to the control (no amendments). Whereas the polymers’ effects on the infiltration rate and runoff relative to each other were inconsistent, PAM with moderate MW was consistently more effective in reducing soil loss than PAM with high MW. For example, in the sandy clay soil, soil losses were reduced from 840 g/m2, in the control, to 570 and 370 g/m2 for the high and moderate MW PAM treatment, respectively. This greater capacity to control soil erosion was ascribed to the lower viscosity of the soil surface solution following dissolution of dry PAM granules in the case of moderate MW PAM, leading to more uniform, effective treatment of soil aggregates at the soil surface by the polymer.
Dealumination as a mechanism for increased acid recoverable aluminium in Waikato mineral soils
Authors: Taylor M. D. , Kim N. D.
Published: December 2009

This paper assesses a potentially interesting soil process, dealumination, as the mechanism for the increase observed in strong acid recoverable Al and associated elements in farmed soils compared with background soils in the Waikato Region of New Zealand. Waikato Regional Council has been measuring an established set of 7 soil quality chemical and physical parameters and concentrations of 33 elements as part of a Regional Soil Quality Monitoring program since 2003. Statistical comparison of farmed to background soils, relative surface enrichments, and inter-element correlations enable us to infer likely and potential sources of those elements which show some form of enrichment.
Acid-recoverable Al is 1.5 times higher (P < 0.0001) in the Waikato region’s farmed soils than its background soils. This increase is not readily explained as an external source of recoverable Al (due to lack of enrichment at the soil surface). However, it could be explained as an increase in the concentration of acid-recoverable Al as a result of accelerated weathering or chemical attack of primary crystalline and short-range order aluminosilicates. In keeping with this interpretation, acid recoverable concentrations of several trace elements that are normally retained inside aluminosilicates (in residual phases) are also significantly higher in farmed than background soils but are not selectively enriched at the soil surface. These include (with enrichment-to-background factors) Li (2.5), La (2.1), Mn (1.5), and Ag, Bi, Mo, Sn, and Tl (1.4). Also, this process may contribute one-quarter of the observed increase in acid-recoverable U. If it is occurring, accelerated Al weathering may be a normal part of an increase in soil productivity, or may be facilitated by an external agent capable of attacking crystalline aluminosilicates. A candidate in the latter category is the F (and/or possibly free HF) in phosphate fertilisers, because this substantially increases Al species in soil porewater. Two specific mechanisms that could favour Al mobilisation from clay surfaces include partial dissolution by local areas of high acidity associated with fertiliser granules, and surface complexation and extraction by the fluoride and residual hydrofluoric acid present in phosphate fertilisers.
Based on the high reactivity between F and both Al and Si, potential exists for significant production of SiF4(g) as another side-effect of phosphate fertiliser use.
Processes and magnitude of CO2, CH4, and N2O fluxes from liming of Australian acidic soils: a review
Authors: Page K. L. , Allen D. E. , Dalal R. C. , Slattery W.
Published: December 2009

Increases in soil acidification have led to large increases in the application of aglime to Australian agricultural soils. The addition of aglime has the potential to increase greenhouse gas (GHG) emissions due to the release of CO2 during the chemical dissolution of aglime and due to pH-induced changes to soil biological processes. Currently, Australia’s GHG accounting system assumes that all the carbon contained in aglime is released to the atmosphere during dissolution in accordance with the Tier 1 methodology of the IPCC. However, a recent approach by TO West and AC McBride has questioned this assumption, hypothesising that a proportion of the carbon from riverine-transported aglime may be sequestered in seawater. In addition, there is presently no capacity within Australia’s carbon accounting system to quantify changes to GHG emissions from lime-induced changes to soil biological processes. Therefore, the primary objective of this review was to examine the chemical and biological processes occurring during the application of aglime and the subsequent fluxes in CO2, N2O, and CH4 from soil, with particular reference to the Australian environment. Estimates for CO2 emissions from aglime application in Australia using the contrasting methodologies of the IPCC and West and McBride were compared. Using the methodology of the IPCC it was determined that from the aglime applied in Australia in 2002, 0.995 Tg of CO2 would have been emitted, whereas this figure was reduced to 0.659–0.860 Tg of CO2 using the methodology of West and McBride. However, the accuracy of these estimates is currently limited by poor understanding of the manner in which aglime moves within the Australian landscapes. In addition, there are only a very small number of Australian studies that have examined the effect of aglime on GHG emissions due to changes in soil biological processes, limiting the ability of Australian modellers to accurately incorporate these processes within the carbon accounting system.
Organic amendments initiate the formation and stabilisation of macroaggregates in a high clay sodic soil
Authors: Clark G. J. , Sale P. W. G. , Tang C.
Published: December 2009

Subsoil constraints present a substantial problem for crop production in many agricultural regions. In particular, soils in temperate grain production areas of Australia are often poorly structured due to high content of sodic clay. An alternative to the standard practice of addition of gypsum is to incorporate organic amendments deep into the subsoil. An incubation experiment was performed for 174 days using several organic amendments. These consisted of wheat shoots, lucerne pellets, canola and chickpea stubbles, chicken manure, peat, and sawdust. Gypsum, an inorganic amendment commonly applied to sodic soil, was included for comparison. The change over 174 days in soil structural properties was measured using wet-sieving. Formation of slaking-resistant macroaggregates >2 mm was most rapid with ‘green plant material’, wheat and lucerne, while the ‘stubbles’ were markedly slower in obtaining the equivalent level of aggregation. However, the largest growth in aggregates after day 56 was shown by the ‘stubble’ and chicken manure amended soils. The gypsum amendment was not capable of forming large, slaking-resistant aggregates >2 mm; this may be attributed to the inability of gypsum to stimulate soil biological processes. Peat and sawdust failed to initiate slaking-resistant macroaggregates. The study demonstrated that a variety of organic amendments have the ability to improve the physical fertility of sodic subsoil, and in the case of the green plant materials within 1 week of incubation.
Inflammation and adipose tissue macrophages in lipodystrophic mice
Authors: Herrero Laura , Shapiro Hagit , Nayer Ali , Lee Jongsoon , Shoelson Steven E.
Published: December 2009

Lipodystrophy and obesity are opposites in terms of a deficiency versus excess of adipose tissue mass, yet these conditions are accompanied by similar metabolic consequences, including insulin resistance, dyslipidemia, hepatic steatosis, and increased risk for diabetes and atherosclerosis. Hepatic and myocellular steatosis likely contribute to metabolic dysregulation in both states. Inflammation and macrophage infiltration into adipose tissue also appear to participate in the pathogenesis of obesity-induced insulin resistance, but their contributions to lipodystrophy-induced insulin resistance have not been evaluated. We used aP2-nSREBP-1c transgenic (Tg) mice, an established model of lipodystrophy, to ask this question. Circulating cytokine elevations suggested systemic inflammation but even more dramatic was the number of infiltrating macrophages in all white and brown adipose tissue depots of the Tg mice; in contrast, there was no evidence of inflammatory infiltrates or responses in any other tissue including liver. Despite there being overt evidence of adipose tissue inflammation, antiinflammatory strategies including salicylate treatment and genetic suppression of myeloid NF-κB signaling that correct insulin resistance in obesity were ineffective in the lipodystrophic mice. We further showed that adipose tissue macrophages (ATMs) in lipodystrophy and obesity are very different in terms of activation state, gene expression patterns, and response to lipopolysaccharide. Although ATMs are even more abundant in lipodystrophy than in obesity, they have distinct phenotypes and likely roles in tissue remodeling, but do not appear to be involved in the pathogenesis of insulin resistance.
The role of seawater endocytosis in the biomineralization process in calcareous foraminifera
Authors: Bentov Shmuel , Brownlee Colin , Erez Jonathan
Published: December 2009

Foraminifera are unicellular organisms that inhabit the oceans in various ecosystems. The majority of the foraminifera precipitate calcitic shells and are among the major CaCO
3
producers in the oceans. They comprise an important component of the global carbon cycle and also provide valuable paleoceanographic information based on the relative abundance of stable isotopes and trace elements (proxies) in their shells. Understanding the biomineralization processes in foraminifera is important for predicting their calcification response to ocean acidification and for reliable interpretation of the paleoceanographic proxies. Most models of biomineralization invoke the involvement of membrane ion transporters (channels and pumps) in the delivery of Ca
2+
and other ions to the calcification site. Here we show, in contrast, that in the benthic foraminiferan
Amphistegina lobifera
, (a shallow water species), transport of seawater via fluid phase endocytosis may account for most of the ions supplied to the calcification site. During their intracellular passage the seawater vacuoles undergo alkalization that elevates the CO
3
2−
concentration and further enhances their calcifying potential. This mechanism of biomineralization may explain why many calcareous foraminifera can be good recorders of paleoceanographic conditions. It may also explain the sensitivity to ocean acidification that was observed in several planktonic and benthic species.
Uncoupling of sustained MAMP receptor signaling from early outputs in an Arabidopsis endoplasmic reticulum glucosidase II allele
Authors: Lu Xunli , Tintor Nico , Mentzel Tobias , Kombrink Erich , Boller Thomas , Robatzek Silke , Schulze-Lefert Paul , Saijo Yusuke
Published: December 2009

Recognition of microbe-associated molecular patterns (MAMPs), conserved structures typical of a microbial class, triggers immune responses in eukaryotes. This is accompanied by a diverse set of physiological responses that are thought to enhance defense activity in plants. However, the extent and mechanisms by which MAMP-induced events contribute to host immunity are poorly understood. Here we reveal Arabidopsis
priority in sweet life4
(
psl4
) and
psl5
mutants that are insensitive to the bacterial elongation factor (EF)-Tu epitope elf18 but responsive to flagellin epitope flg22. PSL4 and PSL5, respectively, identify β- and α-subunits of endoplasmic reticulum-resident glucosidase II, which is essential for stable accumulation and quality control of the elf18 receptor EFR but not the flg22 receptor FLS2. We notice that EFR signaling is partially and differentially impaired without a significant decrease of the receptor steady-state levels in 2 weakly dysfunctional
gII
α alleles, designated
psl5
-1 and
rsw3
. Remarkably,
rsw3
plants exhibit marked supersusceptibility against a virulent bacterial phytopathogen despite nearly intact coactivation of MAPKs, reactive oxygen species, ethylene biosynthesis, and callose deposition in response to elf18, demonstrating that these signaling outputs alone are insufficient to mount effective immunity. However,
rsw3
plants fail to maintain high transcript levels of defense-promoting
WRKY
,
PR1, and PR2
genes at late time points (4 to 24 h) after elf18 elicitation. This points to an unexpected separation between initial and sustained activation of EFR-mediated signaling in the absence of proper glucosidase II-mediated endoplasmic reticulum quality control. Our findings strongly suggest the importance of sustained MAMP receptor signaling as a key step in the establishment of robust immunity.
Alterations of the Notch pathway in lung cancer
Authors: Westhoff Britta , Colaluca Ivan N. , D'Ario Giovanni , Donzelli Maddalena , Tosoni Daniela , Volorio Sara , Pelosi Giuseppe , Spaggiari Lorenzo , Mazzarol Giovanni , Viale Giuseppe , Pece Salvatore , Di Fiore Pier Paolo
Published: December 2009

Notch signaling regulates cell specification and homeostasis of stem cell compartments, and it is counteracted by the cell fate determinant Numb. Both Numb and Notch have been implicated in human tumors. Here, we show that Notch signaling is altered in approximately one third of non–small-cell lung carcinomas (NSCLCs), which are the leading cause of cancer-related deaths: in ≈30% of NSCLCs, loss of Numb expression leads to increased Notch activity, while in a smaller fraction of cases (around 10%), gain-of-function mutations of the
NOTCH-1
gene are present. Activation of Notch correlates with poor clinical outcomes in NSCLC patients without TP53 mutations. Finally, primary epithelial cell cultures, derived from NSCLC harboring constitutive activation of the Notch pathway, are selectively killed by inhibitors of Notch (γ-secretase inhibitors), showing that the proliferative advantage of these tumors is dependent upon Notch signaling. Our results show that the deregulation of the Notch pathway is a relatively frequent event in NSCLCs and suggest that it might represent a possible target for molecular therapies in these tumors.
High resilience in the Yamal-Nenets social–ecological system, West Siberian Arctic, Russia
Authors: Forbes Bruce C. , Stammler Florian , Kumpula Timo , Meschtyb Nina , Pajunen Anu , Kaarlejärvi Elina
Published: December 2009

Tundra ecosystems are vulnerable to hydrocarbon development, in part because small-scale, low-intensity disturbances can affect vegetation, permafrost soils, and wildlife out of proportion to their spatial extent. Scaling up to include human residents, tightly integrated arctic social-ecological systems (SESs) are believed similarly susceptible to industrial impacts and climate change. In contrast to northern Alaska and Canada, most terrestrial and aquatic components of West Siberian oil and gas fields are seasonally exploited by migratory herders, hunters, fishers, and domesticated reindeer (
Rangifer tarandus
L.). Despite anthropogenic fragmentation and transformation of a large proportion of the environment, recent socioeconomic upheaval, and pronounced climate warming, we find the Yamal-Nenets SES highly resilient according to a few key measures. We detail the remarkable extent to which the system has successfully reorganized in response to recent shocks and evaluate the limits of the system's capacity to respond. Our analytical approach combines quantitative methods with participant observation to understand the overall effects of rapid land use and climate change at the level of the entire Yamal system, detect thresholds crossed using surrogates, and identify potential traps. Institutional constraints and drivers were as important as the documented ecological changes. Particularly crucial to success is the unfettered movement of people and animals in space and time, which allows them to alternately avoid or exploit a wide range of natural and anthropogenic habitats. However, expansion of infrastructure, concomitant terrestrial and freshwater ecosystem degradation, climate change, and a massive influx of workers underway present a looming threat to future resilience.