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https://www.readbyqxmd.com/read/27912011/reduced-snow-cover-alters-root-microbe-interactions-and-decreases-nitrification-rates-in-a-northern-hardwood-forest
#1
Patrick O Sorensen, Pamela H Templer, Lynn Christenson, Jorge Duran, Timothy Fahey, Melany C Fisk, Peter M Groffman, Jennifer L Morse, Adrien C Finzi
Snow cover is projected to decline during the next century in many ecosystems that currently experience a seasonal snowpack. Because snow insulates soils from frigid winter air temperatures, soils are expected to become colder and experience more winter soil freeze-thaw cycles as snow cover continues to decline. Tree roots are adversely affected by snowpack reduction, but whether loss of snow will affect root-microbe interactions remains largely unknown. The objective of this study was to distinguish and attribute direct (e...
December 2016: Ecology
https://www.readbyqxmd.com/read/27911879/interface-electronic-structure-at-the-topological-insulator-ferrimagnetic-insulator-junction
#2
Y Kubota, K Murata, J Miyawaki, K Ozawa, M C Onbasli, T Shirasawa, B Feng, Sh Yamamoto, R-Y Liu, S Yamamoto, S K Mahatha, P Sheverdyaeva, P Moras, C A Ross, S Suga, Y Harada, K L Wang, I Matsuda
An interface electron state at the junction between a three-dimensional topological insulator film, Bi2Se3, and a ferrimagnetic insulator film, Y3Fe5O12 (YIG), was investigated by measurements of angle-resolved photoelectron spectroscopy and x-ray absorption magnetic circular dichroism. The surface state of the Bi2Se3 film was directly observed and localized 3d spin states of the Fe(3+) in the YIG film were confirmed. The proximity effect is likely described in terms of the exchange interaction between the localized Fe 3d electrons in the YIG film and delocalized electrons of the surface and bulk states in the Bi2Se3 film...
December 2, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/27911554/thermal-spin-dynamics-of-yttrium-iron-garnet
#3
Joseph Barker, Gerrit E W Bauer
The magnetic insulator yttrium iron garnet can be grown with near perfection and is therefore and ideal conduit for spin currents. It is a complex material with 20 magnetic moments in the unit cell. In spite of being a ferrimagnet, YIG is almost always modeled as a simple ferromagnet with a single spin wave mode. We use the method of atomistic spin dynamics to study the temperature evolution of the full spin wave spectrum, in quantitative agreement with neutron scattering experiments. The antiferromagnetic or optical mode is found to suppress the spin Seebeck effect at room temperature and beyond due to thermally pumped spin currents with opposite polarization to the ferromagnetic mode...
November 18, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27911533/giant-isotropic-nernst-effect-in-an-anisotropic-kondo-semimetal
#4
Ulrike Stockert, Peijie Sun, Niels Oeschler, Frank Steglich, Toshiro Takabatake, Piers Coleman, Silke Paschen
The "failed Kondo insulator" CeNiSn has long been suspected to be a nodal metal, with a node in the hybridization matrix elements. Here we carry out a series of Nernst effect experiments to delineate whether the severely anisotropic magnetotransport coefficients do indeed derive from a nodal metal or can simply be explained by a highly anisotropic Fermi surface. Our experiments reveal that despite an almost twentyfold anisotropy in the Hall conductivity, the large Nernst signal is isotropic. Taken in conjunction with the magnetotransport anisotropy, these results provide strong support for an isotropic Fermi surface with a large anisotropy in quasiparticle mass derived from a nodal hybridization...
November 18, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27911467/a-systematic-investigation-of-the-charging-effect-in-scanning-electron-microscopy-for-metal-nanostructures-on-insulating-substrates
#5
R Flatabø, A Coste, M M Greve
Scanning electron microscopy is perhaps the most important method for investigating and characterizing nanostructures. A well-known challenge in scanning electron microscopy is the investigation of insulating materials. As insulating materials do not provide a path to ground they accumulate charge, evident as image drift and image distortions. In previous work, we have seen that sample charging in arrays of metal nanoparticles on glass substrates leads to a shrinkage effect, resulting in a measurement error in the nanoparticle dimension of up to 15% at 10 kV and a probe current of 80 ± 10 pA...
December 2, 2016: Journal of Microscopy
https://www.readbyqxmd.com/read/27911418/synthesis-and-characterization-of-fe-doped-aluminosilicate-nanotubes-with-enhanced-electron-conductive-properties
#6
Ehsan Shafia, Serena Esposito, Elnaz Bahadori, Marco Armandi, Maela Manzoli, Barbara Bonelli
The goal of the protocol is to synthesize Fe-doped aluminosilicate nanotubes of the imogolite type with the formula (OH)3Al2-xFexO3SiOH. Doping with Fe aims at lowering the band gap of imogolite, an insulator with the chemical formula (OH)3Al2O3SiOH, and at modifying its adsorption properties towards azo-dyes, an important class of organic pollutants of both wastewater and groundwater. Fe-doped nanotubes are obtained in two ways: by direct synthesis, where FeCl3 is added to an aqueous mixture of the Si and Al precursors, and by post-synthesis loading, where preformed nanotubes are put in contact with a FeCl3•6H2O aqueous solution...
November 15, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/27910915/locating-the-quantum-critical-point-of-the-bose-hubbard-model-through-singularities-of-simple-observables
#7
Mateusz Łącki, Bogdan Damski, Jakub Zakrzewski
We show that the critical point of the two-dimensional Bose-Hubbard model can be easily found through studies of either on-site atom number fluctuations or the nearest-neighbor two-point correlation function (the expectation value of the tunnelling operator). Our strategy to locate the critical point is based on the observation that the derivatives of these observables with respect to the parameter that drives the superfluid-Mott insulator transition are singular at the critical point in the thermodynamic limit...
December 2, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27910628/final-design-of-thermal-diagnostic-system-in-spider-ion-source
#8
M Brombin, M Dalla Palma, R Pasqualotto, N Pomaro
The prototype radio frequency source of the ITER heating neutral beams will be first tested in SPIDER test facility to optimize H(-) production, cesium dynamics, and overall plasma characteristics. Several diagnostics will allow to fully characterise the beam in terms of uniformity and divergence and the source, besides supporting a safe and controlled operation. In particular, thermal measurements will be used for beam monitoring and system protection. SPIDER will be instrumented with mineral insulated cable thermocouples, both on the grids, on other components of the beam source, and on the rear side of the beam dump water cooled elements...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910614/upgraded-millimeter-wave-interferometer-for-measuring-the-electron-density-during-the-beam-extraction-in-the-negative-ion-source
#9
T Tokuzawa, M Kisaki, K Nagaoka, K Tsumori, Y Ito, K Ikeda, H Nakano, M Osakabe, Y Takeiri, O Kaneko
The upgraded millimeter-wave interferometer with the frequency of 70 GHz is installed on a large-scaled negative ion source. Measurable line-averaged electron density is from 2 × 10(15) to 3 × 10(18) m(-3) in front of the plasma grid. Several improvements such as the change to shorter wavelength probing with low noise, the installation of special ordered horn antenna, the signal modulation for a high accuracy digital phase detection, the insertion of insulator, and so on, are carried out for the measurement during the beam extraction by applying high voltage...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910603/investigation-on-quench-initiation-and-propagation-characteristics-of-gdbco-coil-co-wound-with-a-stainless-steel-tape-as-turn-to-turn-metallic-insulation
#10
Y G Kim, J B Song, Y H Choi, D G Yang, S G Kim, H G Lee
This paper investigates the quench initiation and propagation characteristics of a metallic insulation (MI) coil by conducting thermal quench tests for a GdBCO single-pancake coil co-wound with a stainless steel tape as the turn-to-turn MI. The test results confirmed that the MI coil exhibited superior thermal and electrical stabilities compared to the conventional coils co-wound with organic insulation material because the operating current could flow along the radial direction due to the existence of a turn-to-turn contact when a local hot spot was generated...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910462/a-precision-cryostat-design-for-manual-and-semi-automated-cryo-plunge-instruments
#11
Christopher J Russo, Steve Scotcher, Martin Kyte
Here we describe a bench-top cryostat system to control the temperature of liquid ethane in a cryo-plunge apparatus designed for biological specimen preparation for electron cryomicroscopy. It comprises a foam insulated Dewar containing a copper cryostat cup, whose temperature is controlled via an active feedback system to within 0.1 K. The device can easily be incorporated into existing manual and semi-automatic cryo-plunge instruments that are not equipped with cryogenic temperature control. Over the course of normal use, we find that using a cryostat is convenient, fast, and does not require special mixtures of cryogens like ethane/propane...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910378/development-and-characterization-of-an-interferometer-for-calorimeter-based-absorbed-dose-to-water-measurements-in-a-medical-linear-accelerator
#12
Everardo Flores-Martinez, Martha J Malin, Larry A DeWerd
The quantity of relevance for external beam radiotherapy is absorbed dose to water (ADW). An interferometer was built, characterized, and tested to measure ADW within the dose range of interest for external beam radiotherapy using the temperature dependence of the refractive index of water. The interferometer was used to measure radiation-induced phase shifts of a laser beam passing through a (10 × 10 × 10) cm(3) water-filled glass phantom, irradiated with a 6 MV photon beam from a medical linear accelerator...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27908142/laser-assisted-field-evaporation-of-metal-oxides-a-time-dependent-density-functional-theory-study
#13
Yu Xia, Zhibing Li
To understand laser-assisted field evaporation of semiconductors and insulators at the microscopic level, we study the time evolution of the electronic and atomic structure of a MgO cluster in high electrostatic fields subjected to strong laser pulses. We find that the critical laser intensity for evaporation decreases linearly as the electrostatic field strength increases. The optical absorption enhancement in high electrostatic field is confirmed by the redshift of the optical absorption spectra, the reduction of the energy gap, and the increase of the absorption cross section...
November 28, 2016: Journal of Chemical Physics
https://www.readbyqxmd.com/read/27908130/exploring-connections-between-statistical-mechanics-and-green-s-functions-for-realistic-systems-temperature-dependent-electronic-entropy-and-internal-energy-from-a-self-consistent-second-order-green-s-function
#14
Alicia Rae Welden, Alexander A Rusakov, Dominika Zgid
Including finite-temperature effects from the electronic degrees of freedom in electronic structure calculations of semiconductors and metals is desired; however, in practice it remains exceedingly difficult when using zero-temperature methods, since these methods require an explicit evaluation of multiple excited states in order to account for any finite-temperature effects. Using a Matsubara Green's function formalism remains a viable alternative, since in this formalism it is easier to include thermal effects and to connect the dynamic quantities such as the self-energy with static thermodynamic quantities such as the Helmholtz energy, entropy, and internal energy...
November 28, 2016: Journal of Chemical Physics
https://www.readbyqxmd.com/read/27906228/holographic-imaging-with-a-hard-x-ray-nanoprobe-ptychographic-versus-conventional-phase-retrieval
#15
A-L Robisch, J Wallentin, A Pacureanu, P Cloetens, T Salditt
We have performed near-field x-ray imaging with simultaneous object and probe reconstruction. By an advanced ptychographic algorithm based on longitudinal and lateral translations, full-field images of nanoscale objects are reconstructed with quantitative contrast values, along with the extended wavefronts used to illuminate the objects. The imaging scheme makes idealizing assumptions on the probe obsolete, and efficiently disentangles phase shifts related to the object from the imperfections in the illumination...
December 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27905403/infusion-with-human-bone-marrow-derived-mesenchymal-stem-cells-improves-%C3%AE-cell-function-in-patients-and-non-obese-mice-with-severe-diabetes
#16
Lirong Li, Hui Hui, Xiaolei Jia, Jie Zhang, Ying Liu, Qianyue Xu, Dalong Zhu
Mesenchymal stem cells (MSCs) transplantation is a promising therapeutic strategy for type 1 diabetes (T1D). However, little is known on whether MSC transplantation can benefit T1D patients with ketoacidosis and its potential actions. Here, we show that infusion with bone marrow MSCs preserves β-cell function in some T1D patients with ketoacidosis by decreasing exogenous insulin requirement and increasing plasma C-peptide levels up to 1-2 years. MSC transplantation increased plasma and islet insulin contents in non-obese diabetic (NOD) mice with severe diabetes...
December 1, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27903907/chromatin-binding-of-gcn5-in-drosophila-is-largely-mediated-by-cp190
#17
Tamer Ali, Marcus Krüger, Sabin Bhuju, Michael Jarek, Marek Bartkuhn, Rainer Renkawitz
Centrosomal 190 kDa protein (CP190) is a promoter binding factor, mediates long-range interactions in the context of enhancer-promoter contacts and in chromosomal domain formation. All Drosophila insulator proteins bind CP190 suggesting a crucial role in insulator function. CP190 has major effects on chromatin, such as depletion of nucleosomes, high nucleosomal turnover and prevention of heterochromatin expansion. Here, we searched for enzymes, which might be involved in CP190 mediated chromatin changes. Eighty percent of the genomic binding sites of the histone acetyltransferase Gcn5 are colocalizing with CP190 binding...
November 29, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27901119/how-does-the-spin-state-of-co-ions-affect-the-insulator-metal-transition-in-bi2a2co2o8-a%C3%A2-%C3%A2-ca-sr-ba
#18
Xiaokun Huang, Weiyi Zhang
The misfit layered Bi2A2Co2O8 (A = Ca, Sr, Ba) compounds experience an insulator to metal transition as A's ionic radius increases. This feature is contradictory to the conventional wisdom that larger lattice constant favors insulating rather than metallic state, and is also difficult to be reconciled using the Anderson weak localization theory. In this paper, we show from the first-principles calculation that an insulator-metal transition takes place from a nonmagnetic low-spin state of Co(3+) ions to a hexagonally arranged intermediate-spin low-spin mixed-state in CoO2 plane when ionic radius increases from Ca to Ba...
November 30, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27901081/driving-a-superconductor-to-insulator-transition-with-random-gauge-fields
#19
H Q Nguyen, S M Hollen, J Shainline, J M Xu, J M Valles
Typically the disorder that alters the interference of particle waves to produce Anderson localization is potential scattering from randomly placed impurities. Here we show that disorder in the form of random gauge fields that act directly on particle phases can also drive localization. We present evidence of a superfluid bose glass to insulator transition at a critical level of this gauge field disorder in a nano-patterned array of amorphous Bi islands. This transition shows signs of metallic transport near the critical point characterized by a resistance , indicative of a quantum phase transition...
November 30, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27900833/integration-of-photothermal-effect-and-heat-insulation-to-efficiently-reduce-reaction-temperature-of-co2-hydrogenation
#20
Wenbo Zhang, Liangbing Wang, Kaiwen Wang, Munir Ullah Khan, Menglin Wang, Hongliang Li, Jie Zeng
The photothermal effect is applied in CO2 hydrogenation to reduce the reaction temperature under illumination by encapsulating Pt nanocubes and Au nanocages into a zeolitic imidazolate framework (ZIF-8). Under illumination, the heat generated by the photothermal effect of Au nanocages is mainly insulated in the ZIF-8 to form a localized high-temperature region, thereby improving the catalytic activity of Pt nanocubes.
November 30, 2016: Small
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