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  • Article
    Parvathaneni A, Malempati SC.
    Cureus. 2023 Oct;15(10):e47601.
    Infection with nontuberculous mycobacteria (NTM) is an increasingly important cause of pulmonary disease, particularly in immunocompromised patients or those suffering from chronic lung conditions. However, though rare, non-tubercular mycobacterial infection and bronchiectasis may also occur in an immunocompetent patient. This unusual condition is typically seen in middle-aged or elderly white females, with bronchiectasis having a predilection for the middle lobe and lingula. Here, we present a similar case of Mycobacterium avium complex (MAC) infection with middle lobe bronchiectasis in an elderly immunocompetent female, recognized as Lady Windermere Syndrome (LWS).
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  • Article
    Zoldák G, Zubrik A, Musatov A, Stupák M, Sedlák E.
    J Biol Chem. 2004 Nov 12;279(46):47601-9.
    Glucose oxidase (GOX; beta-d-glucose:oxygen oxidoreductase) from Aspergillus niger is a dimeric flavoprotein with a molecular mass of 80 kDa/monomer. Thermal denaturation of glucose oxidase has been studied by absorbance, circular dichroism spectroscopy, viscosimetry, and differential scanning calorimetry. Thermal transition of this homodimeric enzyme is irreversible and, surprisingly, independent of GOX concentration (0.2-5.1 mg/ml). It has an apparent transition temperature of 55.8 +/- 1.2 degrees C and an activation energy of approximately 280 kJ/mol, calculated from the Lumry-Eyring model. The thermally denatured state of GOX after recooling has the following characteristics. (i) It retains approximately 70% of the native secondary structure ellipticity; (ii) it has a relatively low intrinsic viscosity, 7.5 ml/g; (iii) it binds ANS; (iv) it has a low Stern-Volmer constant of tryptophan quenching; and (v) it forms defined oligomeric (dimers, trimers, tetramers) structures. It is significantly different from chemically denatured (6.67 m GdmHCl) GOX. Both the thermal and the chemical denaturation of GOX cause dissociation of the flavin cofactor; however, only the chemical denaturation is accompanied by dissociation of the homodimeric GOX into monomers. The transition temperature is independent of the protein concentration, and the properties of the thermally denatured protein indicate that thermally denatured GOX is a compact structure, a form of molten globule-like apoenzyme. GOX is thus an exceptional example of a relatively unstable mesophilic dimeric enzyme with residual structure in its thermally denatured state.
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  • Article
    Song ZD, Bernevig BA.
    Phys Rev Lett. 2022 Jul 22;129(4):047601.
    Magic-angle (θ=1.05°) twisted bilayer graphene (MATBG) has shown two seemingly contradictory characters: the localization and quantum-dot-like behavior in STM experiments, and delocalization in transport experiments. We construct a model, which naturally captures the two aspects, from the Bistritzer-MacDonald (BM) model in a first principle spirit. A set of local flat-band orbitals (f) centered at the AA-stacking regions are responsible to the localization. A set of extended topological semimetallic conduction bands (c), which are at small energetic separation from the local orbitals, are responsible to the delocalization and transport. The topological flat bands of the BM model appear as a result of the hybridization of f and c electrons. This model then provides a new perspective for the strong correlation physics, which is now described as strongly correlated f electrons coupled to nearly free c electrons-we hence name our model as the topological heavy fermion model. Using this model, we obtain the U(4) and U(4)×U(4) symmetries of Refs. [1-5] as well as the correlated insulator phases and their energies. Simple rules for the ground states and their Chern numbers are derived. Moreover, features such as the large dispersion of the charge ±1 excitations [2,6,7], and the minima of the charge gap at the Γ_{M} point can now, for the first time, be understood both qualitatively and quantitatively in a simple physical picture. Our mapping opens the prospect of using heavy-fermion physics machinery to the superconducting physics of MATBG.
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  • Article
    Tang P, Iguchi R, Uchida KI, Bauer GEW.
    Phys Rev Lett. 2022 Jan 28;128(4):047601.
    We formulate a scattering theory of polarization and heat transport through a ballistic ferroelectric point contact. We predict a polarization current under either an electric field or a temperature difference that depends strongly on the direction of the ferroelectric order and can be detected by its magnetic stray field and associated thermovoltage and Peltier effect.
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  • Article
    Xu C, Chen Y, Cai X, Meingast A, Guo X, Wang F, Lin Z, Lo TW, Maunders C, Lazar S, Wang N, Lei D, Chai Y, Zhai T, Luo X, Zhu Y.
    Phys Rev Lett. 2020 Jul 24;125(4):047601.
    Two-dimensional (2D) layered materials have been an exciting frontier for exploring emerging physics at reduced dimensionality, with a variety of exotic properties demonstrated at 2D limit. Here, we report the first experimental discovery of in-plane antiferroelectricity in a 2D material β^{'}-In_{2}Se_{3}, using optical and electron microscopy consolidated by first-principles calculations. Different from conventional 3D antiferroelectricity, antiferroelectricity in β^{'}-In_{2}Se_{3} is confined within the 2D layer and generates the unusual nanostripe ordering: the individual nanostripes exhibit local ferroelectric polarization, whereas the neighboring nanostripes are antipolar with zero net polarization. Such a unique superstructure is underpinned by the intriguing competition between 2D ferroelectric and antiferroelectric ordering in β^{'}-In_{2}Se_{3}, which can be preserved down to single-layer thickness as predicted by calculation. Besides demonstrating 2D antiferroelectricity, our finding further resolves the true nature of the β^{'}-In_{2}Se_{3} superstructure that has been under debate for over four decades.
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  • Article
    Näf S, Escote X, Yañez RE, Ballesteros M, Simón I, Gil P, Megia A, Vendrell J.
    PLoS One. 2012;7(12):e47601.
    CONTEXT: Zinc-α2-Glycoprotein (ZAG) is an adipokine with lipolytic action and is positively associated with adiponectin in adipose tissue. We hypothesize that ZAG may be related with hydrocarbonate metabolism disturbances observed in gestational diabetes mellitus (GDM).
    OBJECTIVE: The aim of this study was to analyze serum ZAG concentration and its relationship with carbohydrate metabolism in pregnant women and its influence on fetal growth.
    DESIGN: 207 pregnant women (130 with normal glucose tolerance (NGT) and 77 with GDM) recruited in the early third trimester and their offspring were studied. Cord blood was obtained at delivery and neonatal anthropometry was assessed in the first 48 hours. ZAG was determined in maternal serum and cord blood.
    RESULTS: ZAG concentration was lower in cord blood than in maternal serum, but similar concentration was observed in NGT and GDM pregnant women. Also similar levels were found between offspring of NGT and GDM women. In the bivariate analysis, maternal ZAG (mZAG) was positively correlated with adiponectin and HDL cholesterol, and negatively correlated with insulin and triglyceride concentrations, and HOMA index. On the other hand, cord blood ZAG (cbZAG) was positively correlated with fat-free mass, birth weight and gestational age at delivery. After adjusting for confounding variables, gestational age at delivery and HDL cholesterol emerged as the sole determinants of cord blood ZAG and maternal ZAG concentrations, respectively.
    CONCLUSION: mZAG was not associated with glucose metabolism during pregnancy. ZAG concentration was lower in cord blood compared with maternal serum. cbZAG was independently correlated with gestational age at delivery, suggesting a role during the accelerated fetal growth during latter pregnancy.
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  • Article
    Harter JW, Kennes DM, Chu H, de la Torre A, Zhao ZY, Yan JQ, Mandrus DG, Millis AJ, Hsieh D.
    Phys Rev Lett. 2018 Jan 26;120(4):047601.
    We have used a combination of ultrafast coherent phonon spectroscopy, ultrafast thermometry, and time-dependent Landau theory to study the inversion symmetry breaking phase transition at T_{c}=200  K in the strongly spin-orbit coupled correlated metal Cd_{2}Re_{2}O_{7}. We establish that the structural distortion at T_{c} is a secondary effect through the absence of any softening of its associated phonon mode, which supports a purely electronically driven mechanism. However, the phonon lifetime exhibits an anomalously strong temperature dependence that decreases linearly to zero near T_{c}. We show that this behavior naturally explains the spurious appearance of phonon softening in previous Raman spectroscopy experiments and should be a prevalent feature of correlated electron systems with linearly coupled order parameters.
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  • Article
    Zhu T, Guo G, Li W, Gao M.
    ACS Omega. 2022 Dec 27;7(51):47601-47609.
    Imogolite nanotubes (INTs) were synthesized from tetraethoxysilane, aluminum nitrate nonahydrate, and ammonia solution by the method of Arancibia-Miranda, and their dispersion was modified by 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) to obtain ionic liquid (IL)-functionalized INTs (INTs-PF6-ILs). Then, the flame retardant INTs-PF6-ILs was complexed with ammonium polyphosphate (APP) and applied to unsaturated polyester resin (UPR). The limiting oxygen index value and the UL-94 level of the UPR/APP/INTs-PF6-ILs composites reached 28 and V-0, respectively. The residual carbon of the composites in thermogravimetric analysis increased by 19.47%, compared with that of pure UPR. The cone calorimeter test result showed that the peak of heat release rate and total heat rate values of the UPR/APP/INTs-PF6-ILs composites were lowered by 41 and 34% than those of the pure UPR, respectively. The effect of heat combustion and the maximum mass loss rate of UPR/APP/INTs-PF6-ILs composites were also greatly decreased. There were no holes or folds observed on the surface of the UPR/APP/INTs-PF6-ILs composites' residual carbon in scanning electron microscopy images. The intact residual carbon could have effectively insulated the heat and oxygen to improve the flame retardant performance.
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  • Article
    Grutter AJ, Kirby BJ, Gray MT, Flint CL, Alaan US, Suzuki Y, Borchers JA.
    Phys Rev Lett. 2015 Jul 24;115(4):047601.
    New mechanisms for achieving direct electric field control of ferromagnetism are highly desirable in the development of functional magnetic interfaces. To that end, we have probed the electric field dependence of the emergent ferromagnetic layer at CaRuO_{3}/CaMnO_{3} interfaces in bilayers fabricated on SrTiO_{3}. Using polarized neutron reflectometry, we are able to detect the ferromagnetic signal arising from a single atomic monolayer of CaMnO_{3}, manifested as a spin asymmetry in the reflectivity. We find that the application of an electric field of 600 kV/m across the bilayer induces a significant increase in this spin asymmetry. Modeling of the reflectivity suggests that this increase corresponds to a transition from canted antiferromagnetism to full ferromagnetic alignment of the Mn^{4+} ions at the interface. This increase from 1 μ_{B} to 2.5-3.0 μ_{B} per Mn is indicative of a strong magnetoelectric coupling effect, and such direct electric field control of the magnetization at an interface has significant potential for spintronic applications.
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  • Article
    Zhang Q, Arikawa T, Kato E, Reno JL, Pan W, Watson JD, Manfra MJ, Zudov MA, Tokman M, Erukhimova M, Belyanin A, Kono J.
    Phys Rev Lett. 2014 Jul 25;113(4):047601.
    We report on the observation of collective radiative decay, or superradiance, of cyclotron resonance (CR) in high-mobility two-dimensional electron gases in GaAs quantum wells using time-domain terahertz magnetospectroscopy. The decay rate of coherent CR oscillations increases linearly with the electron density in a wide range, which is a hallmark of superradiant damping. Our fully quantum mechanical theory provides a universal formula for the decay rate, which reproduces our experimental data without any adjustable parameter. These results firmly establish the many-body nature of CR decoherence in this system, despite the fact that the CR frequency is immune to electron-electron interactions due to Kohn's theorem.
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  • Article
    Doherty MW, Struzhkin VV, Simpson DA, McGuinness LP, Meng Y, Stacey A, Karle TJ, Hemley RJ, Manson NB, Hollenberg LC, Prawer S.
    Phys Rev Lett. 2014 Jan 31;112(4):047601.
    The negatively charged nitrogen-vacancy (NV-) center in diamond has realized new frontiers in quantum technology. Here, the optical and spin resonances of the NV- center are observed under hydrostatic pressures up to 60 GPa. Our results motivate powerful new techniques to measure pressure and image high-pressure magnetic and electric phenomena. Additionally, molecular orbital analysis and semiclassical calculations provide insight into the effects of compression on the electronic orbitals of the NV- center.
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  • Article
    Chen P, Cosgriff MP, Zhang Q, Callori SJ, Adams BW, Dufresne EM, Dawber M, Evans PG.
    Phys Rev Lett. 2013 Jan 25;110(4):047601.
    The remnant polarization of weakly coupled ferroelectric-dielectric superlattices is distributed unequally between the component layers, and as a result the components respond differently to applied electric fields. The difference is apparent in both the nanometer-scale structure of striped polarization domains and in the development of piezoelectric strain and field-induced polarization. Both effects are probed with in situ time-resolved synchrotron x-ray diffraction in a PbTiO(3)/SrTiO(3) superlattice in fields up to 2.38 MV/cm. Domains are initially distorted to increase the polarization in the SrTiO(3) layer while retaining the striped motif. The subsequent transformation to a uniform polarization state at a later time leads to piezoelectric expansion dominated by the field-induced polarization of the SrTiO(3) layers. The results are consistent with theoretical predictions of the field dependence of the domain structure and electrical polarization.
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  • Article
    Lubk A, Rossell MD, Seidel J, He Q, Yang SY, Chu YH, Ramesh R, Hÿtch MJ, Snoeck E.
    Phys Rev Lett. 2012 Jul 27;109(4):047601.
    Domain walls (DWs) substantially influence a large number of applications involving ferroelectric materials due to their limited mobility when shifted during polarization switching. The discovery of greatly enhanced conduction at BiFeO(3) DWs has highlighted yet another role of DWs as a local material state with unique properties. However, the lack of precise information on the local atomic structure is still hampering microscopical understanding of DW properties. Here, we examine the atomic structure of BiFeO(3) 109° DWs with pm precision by a combination of high-angle annular dark-field scanning transmission electron microscopy and a dedicated structural analysis. By measuring simultaneously local polarization and strain, we provide direct experimental proof for the straight DW structure predicted by ab initio calculations as well as the recently proposed theory of diffuse DWs, thus resolving a long-standing discrepancy between experimentally measured and theoretically predicted DW mobilities.
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  • Article
    Rossell MD, Erni R, Prange MP, Idrobo JC, Luo W, Zeches RJ, Pantelides ST, Ramesh R.
    Phys Rev Lett. 2012 Jan 27;108(4):047601.
    We determine the atomic structure of the pseudotetragonal T phase and the pseudorhombohedral R phase in highly strained multiferroic BiFeO(3) thin films by using a combination of atomic-resolution scanning transmission electron microscopy and electron energy-loss spectroscopy. The coordination of the Fe atoms and their displacement relative to the O and Bi positions are assessed by direct imaging. These observations allow us to interpret the electronic structure data derived from electron energy-loss spectroscopy and provide evidence for the giant spontaneous polarization in strained BiFeO(3) thin films.
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  • Article
    Barnes E, Economou SE.
    Phys Rev Lett. 2011 Jul 22;107(4):047601.
    We introduce a method for solving the problem of an externally controlled electron spin in a quantum dot interacting with host nuclei via the hyperfine interaction. Our method accounts for generalized (nonunitary) evolution effected by external controls and the environment, such as coherent lasers combined with spontaneous emission. As a concrete example, we develop the microscopic theory of the dynamics of nuclear-induced frequency focusing as first measured in Science 317, 1896 (2007); we find that the nuclear relaxation rates are several orders of magnitude faster than those quoted in that work.
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  • Article
    Oak MA, Lee JH, Jang HM, Goh JS, Choi HJ, Scott JF.
    Phys Rev Lett. 2011 Jan 28;106(4):047601.
    Recent studies on the ferroelectricity origin of YMnO(3), a prototype of hexagonal manganites (h-RMnO(3), where R is a rare-earth-metal element), reveal that the d(0)-ness of a Y(3+) ion with an anisotropic Y 4d-O 2p hybridization is the main driving force of ferroelectricity. InMnO(3) (IMO) also belongs to the h-RMnO(3) family. However, the d(0)-ness-driven ferroelectricity cannot be expected because the trivalent In ion is characterized by a fully filled 4d orbital. Here we propose a new bonding mechanism of the hexagonal ferroelectricity in IMO: intra-atomic 4d(z(2))-5p(z) orbital mixing of In followed by asymmetric 4d(z(2))(In)-2p(z)(O) covalent bonding along the c axis.
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  • Article
    Hatch RC, Huber DL, Höchst H.
    Phys Rev Lett. 2010 Jan 29;104(4):047601.
    The electron-phonon (e-p) interaction in pentacene (Pn) films grown on Bi(001) was investigated using photoemission spectroscopy. The spectra reveal thermal broadening from which we determine an e-p mass enhancement factor of lambda=0.36+/-0.05 and an effective Einstein energy of omega{E}=11+/-4 meV. From omega{E} it is inferred that dominant contributions to the e-p effects observed in angle-resolved photoemission spectroscopy come from intermolecular vibrations. Based on the experimental data for lambda we extract an effective Peierls coupling value of g{eff}=0.55. The e-p coupling narrows the highest occupied molecular orbital bandwidth by 15+/-8% between 75 and 300 K.
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  • Article
    Varga T, Kumar A, Vlahos E, Denev S, Park M, Hong S, Sanehira T, Wang Y, Fennie CJ, Streiffer SK, Ke X, Schiffer P, Gopalan V, Mitchell JF.
    Phys Rev Lett. 2009 Jul 24;103(4):047601.
    We report the magnetic and electrical characteristics of polycrystalline FeTiO_{3} synthesized at high pressure that is isostructural with acentric LiNbO_{3} (LBO). Piezoresponse force microscopy, optical second harmonic generation, and magnetometry demonstrate ferroelectricity at and below room temperature and weak ferromagnetism below approximately 120 K. These results validate symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and weak ferromagnetism in a series of transition metal titanates crystallizing in the LBO structure.
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  • Article
    Wang RV, Fong DD, Jiang F, Highland MJ, Fuoss PH, Thompson C, Kolpak AM, Eastman JA, Streiffer SK, Rappe AM, Stephenson GB.
    Phys Rev Lett. 2009 Jan 30;102(4):047601.
    According to recent experiments and predictions, the orientation of the polarization at the surface of a ferroelectric material can affect its surface chemistry. Here we demonstrate the converse effect: the chemical environment can control the polarization orientation in a ferroelectric film. In situ synchrotron x-ray scattering measurements show that high or low oxygen partial pressure induces outward or inward polarization, respectively, in an ultrathin PbTiO3 film. Ab initio calculations provide insight into surface structure changes observed during chemical switching.
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  • Article
    Takahashi S, Hanson R, van Tol J, Sherwin MS, Awschalom DD.
    Phys Rev Lett. 2008 Jul 25;101(4):047601.
    We experimentally demonstrate that the decoherence of a spin by a spin bath can be completely eliminated by fully polarizing the spin bath. We use electron paramagnetic resonance at 240 GHz and 8 T to study the electron-spin coherence time T2 of nitrogen-vacancy centers and nitrogen impurities in diamond from room temperature down to 1.3 K. A sharp increase of T2 is observed below the Zeeman energy (11.5 K). The data are well described by a suppression of the flip-flop induced spin bath fluctuations due to thermal electron-spin polarization. T2 saturates at approximately 250 micros below 2 K, where the polarization of the electron-spin bath exceeds 99%.
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