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Janusz Edward Jacak
Recent experimental progress in Hall measurements in bilayer graphene in the so-called open-face configuration of boron nitride encapsulated samples, together with the earlier technique of suspended samples, allows for precise observation of the fractional quantum Hall effect (FQHE) in all 4 subbands of the Lowest Landau level (with n = 0 and n = 1) and in the next LL subbands (with n = 2) in the bilayer system. Many newly observed FQHE features do not agree with a conventional model of composite fermions and reveal a different hierarchy in comparison to monolayer graphene or GaAs 2DEG...
August 18, 2017: Scientific Reports
S Vivekanandan, D B Landau, N Counsell, D R Warren, A Khwanda, S D Rosen, E Parsons, Y Ngai, L Farrelly, L Hughes, M A Hawkins, J D Fenwick
PURPOSE: The heart receives high radiation doses during radiation therapy of advanced-stage lung cancer. We have explored associations between overall survival, cardiac radiation doses, and electrocardiographic (ECG) changes in patients treated in IDEAL-CRT, a trial of isotoxically escalated concurrent chemoradiation delivering tumor doses of 63 to 73 Gy. METHODS AND MATERIALS: Dosimetric and survival data were analyzed for 78 patients. The whole heart, pericardium, AV node, and walls of left and right atria (LA/RA-Wall) and ventricles (LV/RV-Wall) were outlined on radiation therapy planning scans, and differential dose-volume histograms (dDVHs) were calculated...
September 1, 2017: International Journal of Radiation Oncology, Biology, Physics
Guojie Zhang, Marcus Müller
Membrane fission is a fundamental process in cells, involved inter alia in endocytosis, intracellular trafficking, and virus infection. Its underlying molecular mechanism, however, is only incompletely understood. Recently, experiments and computer simulation studies have revealed that dynamin-mediated membrane fission is a two-step process that proceeds via a metastable hemi-fission intermediate (or wormlike micelle) formed by dynamin's constriction. Importantly, this hemi-fission intermediate is remarkably metastable, i...
August 14, 2017: Journal of Chemical Physics
N A Usov, O N Serebryakova, V P Tarasov
A specific absorption rate of a dilute assembly of various random clusters of iron oxide nanoparticles in alternating magnetic field has been calculated using Landau-Lifshitz stochastic equation. This approach simultaneously takes into account both the presence of thermal fluctuations of the nanoparticle magnetic moments and magneto-dipole interaction between the nanoparticles of the clusters. It is shown that for usual 3D clusters, the intensity of the magneto-dipole interaction is determined mainly by the cluster packing density η = N p V/V cl , where N p is the average number of the particles in the cluster, V is the nanoparticle volume, and V cl is the cluster volume...
August 14, 2017: Nanoscale Research Letters
Clevin Handschin, Péter Makk, Peter Rickhaus, Romain Maurand, Kenji Watanabe, Takashi Taniguchi, Klaus Richter, Ming-Hao Liu, Christian Schönenberger
At high magnetic fields the conductance of graphene is governed by the half-integer quantum Hall effect. By local electrostatic gating a p-n junction perpendicular to the graphene edges can be formed, along which quantum Hall channels copropagate. It has been predicted by Tworzidło and co-workers that if only the lowest Landau level is filled on both sides of the junction, the conductance is determined by the valley (isospin) polarization at the edges and by the width of the flake. This effect remained hidden so far due to scattering between the channels copropagating along the p-n interface (equilibration)...
August 17, 2017: Nano Letters
Dongwoo Shin, Yongwoo Lee, M Sasaki, Yoon Hee Jeong, Franziska Weickert, Jon B Betts, Heon-Jung Kim, Ki-Seok Kim, Jeehoon Kim
Ohm's law is a fundamental paradigm in the electrical transport of metals. Any transport signatures violating Ohm's law would give an indisputable fingerprint for a novel metallic state. Here, we uncover the breakdown of Ohm's law owing to a topological structure of the chiral anomaly in the Weyl metal phase. We observe nonlinear I-V characteristics in Bi0.96Sb0.04 single crystals in the diffusive limit, which occurs only for a magnetic-field-aligned electric field (E∥B). The Boltzmann transport theory with the charge pumping effect reveals the topological-in-origin nonlinear conductivity, and it leads to a universal scaling function of the longitudinal magnetoconductivity, which completely describes our experimental results...
August 14, 2017: Nature Materials
Kulsoom Rahim, Ahsan Ullah, Muhammad Tahir, Kashif Sabeeh
We determine the optical response of ultrathin film topological insulators in the presence of a quantizing external magnetic field taking into account both hybridization between surface states, broken inversion symmetry and explicit time reversal symmetry breaking by the magnetic field. We find that breaking of inversion symmetry in the system, which can be due to interaction with a substrate or electrical gating, results in Landau level crossings and opening of additional optical transition channels that were previously forbidden...
August 14, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
A Hausoel, M Karolak, E Şaşιoğlu, A Lichtenstein, K Held, A Katanin, A Toschi, G Sangiovanni
Some Bravais lattices have a particular geometry that can slow down the motion of Bloch electrons by pre-localization due to the band-structure properties. Another known source of electronic localization in solids is the Coulomb repulsion in partially filled d or f orbitals, which leads to the formation of local magnetic moments. The combination of these two effects is usually considered of little relevance to strongly correlated materials. Here we show that it represents, instead, the underlying physical mechanism in two of the most important ferromagnets: nickel and iron...
July 12, 2017: Nature Communications
Shi-Yu Liu, Yang Meng, Shiyang Liu, De-Jun Li, Yaping Li, Yingdi Liu, Yaogen Shen, Sanwu Wang
With extensive first-principles density-functional calculations, we construct a three-dimensional compositional phase diagram of Ba1-xCaxZryTi1-yO3 (BCZT) with the Ca and Zr content in the ranges of 0 ≤ xCa ≤ 0.2 and 0 ≤ yZr ≤ 1. Our calculations show that, when the Zr content increases, the difference in energy and difference in the structural parameters of the cubic, tetragonal, orthorhombic, and rhombohedral phases of BCZT are reduced. Eventually, all four phases merge into a multiphase with coexisting cubic structures (MPCCS) under Zr-rich conditions, indicating that BCZT undergoes phase transition from a normal ferroelectric (NFE) to a relaxor ferroelectric (RFE), consistent with experimental observations...
August 10, 2017: Physical Chemistry Chemical Physics: PCCP
Eran Hadad, Itay Wiser, Adaya Rosenthal, Geva Landau, Ella Ziv, Lior Heller
BACKGROUND AND OBJECTIVE: Surgical site infection (SSI) following esthetic breast implant exchange occurs in up to 2% of procedures. The effect of suction drains on SSI risk in these cases remains controversial. This study aimed to assess the SSI risk in the presence of suction drains after esthetic exchange of breast implants. METHODS: This is a retrospective cohort study of patients undergoing esthetic breast implant exchange between 2012 and 2015. SSI was determined according to the definition of the Center for Disease Control and Prevention...
July 6, 2017: Journal of Plastic, Reconstructive & Aesthetic Surgery: JPRAS
Sigurdur I Erlingsson, Andrei Manolescu, George Alexandru Nemnes, Jens H Bardarson, David Sanchez
We calculate the charge current generated by a temperature bias between the two ends of a tubular nanowire. We show that in the presence of a transversal magnetic field the current can change sign; i.e., electrons can either flow from the hot to the cold reservoir, or in the opposite direction, when the temperature bias increases. This behavior occurs when the magnetic field is sufficiently strong, such that Landau and snaking states are created, and the energy dispersion is nonmonotonic with respect to the longitudinal wave vector...
July 21, 2017: Physical Review Letters
Muhammad Tahir, Panagiotis Vasilopoulos
The recent experimental realization of high-quality phosphorene leads to novel electronic and optical properties with possible new device applications due to its huge direct band gap. We study the commensurability or Weiss oscillations in monolayer phosphorene in the presence of a weak perpendicular magnetic field $B$ and a weak and periodic, electric or magnetic one-dimensional (1D) modulation. Either modulation broadens the Landau levels (LLs) into bands, whose width oscillates with $B$, and the oscillations appear in the electrical conductivity perpendicular to the modulation taken along the direction ($x$) of the smaller effective mass...
August 4, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Huan Tang, Ying Zhao, Xiaonan Yang, Dongmei Liu, Penghui Shao, Zhigao Zhu, Sujie Shan, Fuyi Cui, Baoshan Xing
A comparative experimental and molecular dynamics (MD) simulation study was carried out to investigate the aggregation of graphene oxide (GO). Mechanisms behind the effects of solution chemistries (pH, metal ions, and tannic acid (TA)) and GO topology (carboxyl content, GO size, and GO thickness) were uncovered. For example, MD results showed that more hydrogen bonds formed between GO and water at higher pH, according well with the increased hydrophilicity of GO calculated based on contact angle measurements...
August 3, 2017: Environmental Science & Technology
Yijue Diao, Mengwei Han, Josue A Lopez-Berganza, Lauren Valentino, Benito J Marinas, Rosa M Espinosa-Marzal
Recognizing the significance of surface interactions for ion rejection and membrane fouling in nanofiltra-tion, we revise the theories of DLVO (named after Derjaguin, Landau, Verwey, and Overbeek) and non-DLVO forces in the context of polyamide active layers. Using an atomic force microscope, surface forces between polyamide active layers and a micrometer-large and smooth silica colloid were measured in elec-trolyte solutions of representative monovalent and divalent ions. While the analysis of DLVO forces, ac-counting for surface roughness, provides how surface charge of the active layer changes with electrolyte concentration, scrutiny of non-DLVO hydration forces gives molecular insight into the composition of the membrane-solution interface...
August 3, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Hesang Im, Younghoon Oh, Hyun Woo Cho, Jeongmin Kim, Keewook Paeng, Bong June Sung
The spatial arrangement of nanoparticles (NPs) within thin polymer films may influence their properties such as the glass transition temperature. Questions regarding what may affect the spatial arrangement of NPs, however, still remain unanswered at a molecular level. In this work, we perform molecular dynamics simulations for a free-standing thin polymer film with a single NP. We find from simulations that depending on the NP size and the inter-particle interaction between the NP and polymers, one may control the spatial arrangement of the NP...
August 2, 2017: Soft Matter
Fabian Lengwiler, Daniel Rappoport, Gregor P Jaggi, Klara Landau, Ghislaine L Traber
BACKGROUND/AIMS: To evaluate inter-rater and intra-rater reliability of objective cyclotorsion measurements obtained in healthy subjects using the Heidelberg Spectralis spectral domain-optical coherence tomography (SD-OCT) device. METHODS: In this prospective methodological study, 32 healthy subjects (14 men, 18 women; aged 21-64 years) were enrolled, 31 right eyes were examined and their foveo-papillary angles (FPAs) were measured. The retinal nerve fibre layer (RNFL) programme by Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany) was used to measure cyclotorsion based on the in-built algorithm for the measurement of the FPA on the scanning laser ophthalmoscopy (SLO) image...
August 1, 2017: British Journal of Ophthalmology
Bidesh K Bera, Dibakar Ghosh, Punit Parmananda, G V Osipov, Syamal K Dana
We report the emergence of coexisting synchronous and asynchronous subpopulations of oscillators in one dimensional arrays of identical oscillators by applying a self-feedback control. When a self-feedback is applied to a subpopulation of the array, similar to chimera states, it splits into two/more sub-subpopulations coexisting in coherent and incoherent states for a range of self-feedback strength. By tuning the coupling between the nearest neighbors and the amount of self-feedback in the perturbed subpopulation, the size of the coherent and the incoherent sub-subpopulations in the array can be controlled, although the exact size of them is unpredictable...
July 2017: Chaos
Jin Xu, Dong-Ho Park, Junghyo Jo
We study the global synchronization of hierarchically-organized Stuart-Landau oscillators, where each subsystem consists of three oscillators with activity-dependent couplings. We considered all possible coupling signs between the three oscillators, and found that they can generate different numbers of phase attractors depending on the network motif. Here, the subsystems are coupled through mean activities of total oscillators. Under weak inter-subsystem couplings, we demonstrate that the synchronization between subsystems is highly correlated with the number of attractors in uncoupled subsystems...
July 2017: Chaos
Allison J Lee, Ruth Landau
More than 70 years ago, the phenomenon of "postural shock" in the supine position was described in healthy women in late pregnancy. Since then, avoidance of the supine position has become a key component of clinical practice. Indeed, performing pelvic tilt in mothers at term to avoid aortocaval compression is a universally adopted measure, particularly during cesarean delivery. The studies on which this practice is based are largely nonrandomized, utilized a mix of anesthetic techniques, and were conducted decades ago in the setting of avoidance of vasopressors...
July 27, 2017: Anesthesia and Analgesia
Biljana Uzelac, Valentina Valmacco, Gregor Trefalt
Forces between charged silica particles in solutions of multivalent coions are measured with colloidal probe technique based on atomic force microscopy. The concentration of 1 : z electrolytes is systematically varied to understand the behavior of electrostatic interactions and double-layer properties in these systems. Although the coions are multivalent the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory perfectly describes the measured force profiles. The diffuse-layer potentials and regulation properties are extracted from the forces profiles by using the DLVO theory...
July 31, 2017: Soft Matter
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