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enhancer insulator

Hannes Hübener, Michael A Sentef, Umberto De Giovannini, Alexander F Kemper, Angel Rubio
Tuning and stabilizing topological states, such as Weyl semimetals, Dirac semimetals or topological insulators, is emerging as one of the major topics in materials science. Periodic driving of many-body systems offers a platform to design Floquet states of matter with tunable electronic properties on ultrafast timescales. Here we show by first principles calculations how femtosecond laser pulses with circularly polarized light can be used to switch between Weyl semimetal, Dirac semimetal and topological insulator states in a prototypical three-dimensional (3D) Dirac material, Na3Bi...
January 17, 2017: Nature Communications
S Manna, A Kamlapure, L Cornils, T Hänke, E M J Hedegaard, M Bremholm, B B Iversen, Ph Hofmann, J Wiebe, R Wiesendanger
The discovery of high-temperature superconductivity in Fe-based compounds triggered numerous investigations on the interplay between superconductivity and magnetism, and on the enhancement of transition temperatures through interface effects. It is widely believed that the emergence of optimal superconductivity is intimately linked to the suppression of long-range antiferromagnetic (AFM) order, although the exact microscopic picture remains elusive because of the lack of atomically resolved data. Here we present spin-polarized scanning tunnelling spectroscopy of ultrathin FeTe1-xSex (x=0, 0...
January 17, 2017: Nature Communications
Soudabeh Mashhadi, Dinh Loc Duong, Marko Burghard, Klaus Kern
Tuning the electron and phonon transport properties of thermoelectric materials by nanostructuring has enabled improving their thermopower figure of merit. Three-dimensional topological insulators, including many bismuth chalcogenides, attract increasing attention for this purpose, as their topologically protected surface states are promising to further enhance the thermoelectric performance. While individual bismuth chalcogenide nanostructures have been studied with respect to their photothermoelectric properties, nanostructured p-n junctions of these compounds have not yet been explored...
January 11, 2017: Nano Letters
Yanbo Li, Yukun Ren, Weiyu Liu, Xiaoming Chen, Ye Tao, Hongyuan Jiang
In this study, we develop a nondimensional physical model to demonstrate fluid flow at the micrometer dimension driven by traveling-wave induction electrohydrodynamics (EHD) through direct numerical simulation. In order to realize an enhancement in the pump flow rate as well as a flexible adjustment of anisotropy of flow behavior generated by induction EHD in microchannels, while not adding the risk of causing dielectric breakdown of working solution and material for insulation, a pair of synchronized traveling-wave voltage signals are imposed on double-sided electrode arrays that are mounted on the top and bottom insulating substrate, respectively...
January 9, 2017: Electrophoresis
Junjun Zhang, Wenpei Kang, Miao Jiang, Yu You, Yulin Cao, Tsz-Wai Ng, Denis Y W Yu, Chun-Sing Lee, Jun Xu
S-Doped 2H-MoSe2 (i.e., 2H-MoS2xSe2-2x) mesoporous nanospheres assembled from several-layered nanosheets are synthesized by sulfurizing freshly-prepared 1T-MoSe2 nanospheres, and they serve as a robust host material for sodium storage. The sulfuration treatment is found to be beneficial for removing surface/interface insulating organic contaminants and converting the 1T phase to the 2H phase with improved crystallinity and electrical conductivity. These result in significantly enhanced sodium storage performance, including charge/discharge capacity, first Coulombic efficiency, cycling stability, and rate capability...
January 9, 2017: Nanoscale
Susan J Burke, Heidi M Batdorf, Adrianna E Eder, Michael D Karlstad, David H Burk, Robert C Noland, Z Elizabeth Floyd, J Jason Collier
Steroid-induced diabetes is the most common form of drug-induced hyperglycemia. Therefore, metabolic and immunological alterations associated with chronic oral corticosterone were investigated using male nonobese diabetic mice. Three weeks after corticosterone delivery, there was reduced sensitivity to insulin action measured by insulin tolerance test. Body composition measurements revealed increased fat mass and decreased lean mass. Overt hyperglycemia (>250 mg/dL) manifested 6 weeks after the start of glucocorticoid administration, whereas 100% of the mice receiving the vehicle control remained normoglycemic...
January 4, 2017: American Journal of Pathology
Guangwei Cong, Morifumi Ohno, Yuriko Maegami, Makoto Okano, Koji Yamada
Optical autocorrelation accuracy was for the first time analyzed for the silicon waveguide based autocorrelators utilizing two-photon absorption (TPA) under various short pulse conditions by numerical simulation. As for autocorrelation operation in the sub-μm silicon p-i-n rib waveguides on the 220 nm SOI (silicon on insulator) wafers, the autocorrelation error of pulse width measurement gradually increases with the increase of the peak power for both Gaussian and hyperbolic secant pulses due to the influence of free-carrier absorption (FCA)...
December 26, 2016: Optics Express
Carlito Baltazar Tabelin, Suchol Veerawattananun, Mayumi Ito, Naoki Hiroyoshi, Toshifumi Igarashi
The oxidative dissolution of pyrite is an important process in the redox recycling of iron (Fe) and is well-known for its role in the formation of acid mine drainage (AMD), which is considered as the most serious and widespread problem after the closure of mines and mineral processing operations. Because this process requires the movement of electrons, common metal oxides in nature that have either semiconducting (e.g., hematite) or insulating (e.g., alumina) properties may have strong effects on it. In this study, changes in the electrochemical behavior of pyrite in the presence of hematite and alumina were investigated...
January 3, 2017: Science of the Total Environment
Alex Risos, Nicholas Long, Arvid Hunze, Gideon Gouws
Interdigitated dielectrometry sensors (IDS) are capacitive sensors investigated to precisely measure the relative permittivity ( ϵ r ) of insulating liquids. Such liquids used in the power industry exhibit a change in ϵ r as they degrade. The IDS ability to measure ϵ r in-situ can potentially reduce maintenance, increase grid stability and improve safety. Noise from external electric field sources is a prominent issue with IDS. This paper investigates the novelty of applying a Faraday cage onto an IDS as a 3D shield to reduce this noise...
December 31, 2016: Sensors
Hongzhen Liu, Yanyan Lou, Siriporn Jungsuttiwong, Shuai Yuan, Yin Zhao, Zhuyi Wang, Liyi Shi, Hualan Zhou
Charge recombination and transfer at the TiO2/dye/electrolyte interface play a crucial role in dye-sensitized solar cells (DSSCs). Here, a fine-controlled gold nanoparticle (Au NP) via electrodeposition incorporated into a porous TiO2 photoanode and dodecanethiol molecules as an assembled monolayer capping on Au NPs was designed and prepared. The "fence-like" structure of gold thiol molecules at the TiO2/dye/electrolyte interface can not only insulate the electrolyte to suppress recombination but also make full use of the plasmon-enhanced light absorption of Au NPs...
January 11, 2017: ACS Applied Materials & Interfaces
Jin Hee Lee, Hamza Zad Gul, Hyun Kim, Byoung Hee Moon, Subash Adhikari, Jung Ho Kim, Homin Choi, Young Hee Lee, Seong Chu Lim
We achieve switching on/off the photocurrent of monolayer molybdenum disulfide (MoS2) by controlling the metal-insulator transition (MIT). N-type semiconducting MoS2 under a large negative gate bias generates a photocurrent attributed to the increase of excess carriers in the conduction band by optical excitation. However, under a large positive gate bias, a phase shift from semiconducting to metallic MoS2 is caused, and the photocurrent by excess carriers in the conduction band induced by the laser disappears due to enhanced electron-electron scattering...
January 3, 2017: Nano Letters
W-S Liau, S H Tan, P C T Ngoc, C Q Wang, V Tergaonkar, H Feng, Z Gong, M Osato, A T Look, T Sanda
The transcription factor TAL1/SCL is one of the most prevalent oncogenes in T-cell acute lymphoblastic leukemia (T-ALL), a malignant disorder resulting from leukemic transformation of thymus T-cell precursors. TAL1 is normally expressed in hematopoietic stem cells (HSCs) but is silenced in immature thymocytes. We hypothesize that TAL1 contributes to leukemogenesis by activating genes that are normally repressed in immature thymocytes. Herein, we identified a novel TAL1-regulated super-enhancer controlling the GIMAP locus, which resides within an insulated chromosomal locus in T-ALL cells...
December 28, 2016: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
Po-Yen Chen, Muchun Liu, Thomas M Valentin, Zhongying Wang, Ruben Spitz Steinberg, Jaskiranjeet Sodhi, Ian Y Wong, Robert H Hurt
Confined assembly in the intersheet gallery spaces of two-dimensional (2D) materials is an emerging templating route for creation of ultrathin material architectures. Here, we demonstrate a general synthetic route for transcribing complex wrinkled and crumpled topographies in graphene oxide (GO) films into textured metal oxides. Intercalation of hydrated metal ions into textured GO multilayer films followed by dehydration, thermal decomposition, and air oxidation produces Zn, Al, Mn, and Cu oxide films with high-fidelity replication of the original GO textures, including "multi-generational", multiscale textures that have been recently achieved through extreme graphene compression...
December 27, 2016: ACS Nano
Gwangwoo Kim, Minsu Kim, Chohee Hyun, Seokmo Hong, Kyung Yeol Ma, Hyeon Suk Shin, Hyunseob Lim
We report on an insulating two-dimensional material, hexagonal boron nitride (h-BN), which can be used as an effective wrapping layer for surface-enhanced Raman spectroscopy (SERS) substrates. This material exhibits outstanding characteristics such as its crystallinity, impermeability, and thermal conductance. Improved SERS sensitivity is confirmed for Au substrates wrapped with h-BN, the mechanism of which is investigated via h-BN thickness-dependent experiments combined with theoretical simulations. The investigations reveal that a stronger electromagnetic field can be generated at the narrowed gap of the h-BN surface, which results in higher Raman sensitivity...
December 27, 2016: ACS Nano
Wenjiang Song, Jing Li, Qiang Liang, Mario Andrea Marchisio
BACKGROUND: In bacteria, transcription units can be insulated by placing a terminator in front of a promoter. In this way promoter leakage due to the read-through from an upstream gene or RNA polymerase unspecific binding to the DNA is, in principle, removed. Differently from bacterial terminators, yeast S. cerevisiae terminators contain a hexamer sequence, the efficiency element, that strongly resembles the eukaryotic TATA box i.e. the promoter sequence recognized and bound by RNA polymerase II...
2016: Journal of Biological Engineering
Jessica R Woelfel, Amy L Kimball, Chu-Ling Yen, Richard K Shields
: Reduced physical activity is a primary risk factor for increased morbidity and mortality, People with spinal cord injury (SCI) have reduced activity for a lifetime, as they cannot volitionally activate affected skeletal muscles. We explored whether low force and low frequency stimulation is a viable strategy to enhance systemic energy expenditure in people with SCI. PURPOSE: To determine the effects of low stimulation frequency (1 Hz, 3 Hz) and stimulation intensity (50 mA and 100 mA) on energy expenditure in people with SCI...
December 22, 2016: Medicine and Science in Sports and Exercise
Joseph Dufouleur, Louis Veyrat, Bastien Dassonneville, Christian Nowka, Silke Hampel, Pavel Leksin, Barbara Eichler, Oliver G Schmidt, Bernd Büchner, Romain Giraud
No abstract text is available yet for this article.
December 23, 2016: Nano Letters
Ilya I Klimovskikh, Mikhail M Otrokov, Vladimir Yu Voroshnin, Daria Sostina, Luca Petaccia, Giovanni Di Santo, Sangeeta Thakur, Evgueni V Chulkov, Alexander M Shikin
Graphene is one of the most promising materials for nanoelectronics owing to its unique Dirac cone-like dispersion of the electronic state and high mobility of the charge carriers. However, to facilitate the implementation of the graphene-based devices, an essential change of its electronic structure, a creation of the band gap should controllably be done. Brought about by two fundamentally different mechanisms, a sublattice symmetry breaking or an induced strong spin-orbit interaction, the band gap appearance can drive graphene into a narrow-gap semiconductor or a 2D topological insulator phase, respectively, both cases being technologically relevant...
December 22, 2016: ACS Nano
Adolfo O Fumega, Victor Pardo
In this paper we explore the different mechanisms that affect the thermopower of a band insulating perovskite (in this case, SrTiO3) when subject to strain (both compressive or tensile). We analyze the high temperature, entropy-dominated limit and the lower temperature, energy-transport regime. We observe that the effect of strain in the high-temperature Seebeck coefficient is small at the concentration levels of interest for thermoelectric applications. However, the effective mass changes substantially with strain, which produces an opposite effect to that of the degeneracy breakups brought about by strain...
February 15, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Gabriela B Almeida, Ronei J Poppi, José A Fracassi da Silva
Dielectrophoresis (DEP) is the electrokinetic movement of non-charged particles when they are subjected to a non-uniform electric field. This is a growing area of research, which can be used for trapping, concentrating and separating different particles. Some work has been reported with the intention of trapping metal particles to optimize the surface enhanced Raman spectroscopy (SERS) effect. In this paper, we use DEP with insulating structures (iDEP) to generate a non-uniform electric field for trapping gold nanoparticles (AuNP)...
December 20, 2016: Analyst
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