Science.gov

Sample records for anomalous skin effect

  1. Anomalous skin effects in a weakly magnetized degenerate electron plasma

    NASA Astrophysics Data System (ADS)

    Abbas, G.; Sarfraz, M.; Shah, H. A.

    2014-09-01

    Fully relativistic analysis of anomalous skin effects for parallel propagating waves in a weakly magnetized degenerate electron plasma is presented and a graphical comparison is made with the results obtained using relativistic Maxwellian distribution function [G. Abbas, M. F. Bashir, and G. Murtaza, Phys. Plasmas 18, 102115 (2011)]. It is found that the penetration depth for R- and L-waves for degenerate case is qualitatively small in comparison with the Maxwellian plasma case. The quantitative reduction due to weak magnetic field in the skin depth in R-wave for degenerate plasma is large as compared to the non-degenerate one. By ignoring the ambient magnetic field, previous results for degenerate field free case are salvaged [A. F. Alexandrov, A. S. Bogdankevich, and A. A. Rukhadze, Principles of Plasma Electrodynamics (Springer-Verlag, Berlin/Heidelberg, 1984), p. 90].

  2. Anomalous skin effects in a weakly magnetized degenerate electron plasma

    SciTech Connect

    Abbas, G. Sarfraz, M.; Shah, H. A.

    2014-09-15

    Fully relativistic analysis of anomalous skin effects for parallel propagating waves in a weakly magnetized degenerate electron plasma is presented and a graphical comparison is made with the results obtained using relativistic Maxwellian distribution function [G. Abbas, M. F. Bashir, and G. Murtaza, Phys. Plasmas 18, 102115 (2011)]. It is found that the penetration depth for R- and L-waves for degenerate case is qualitatively small in comparison with the Maxwellian plasma case. The quantitative reduction due to weak magnetic field in the skin depth in R-wave for degenerate plasma is large as compared to the non-degenerate one. By ignoring the ambient magnetic field, previous results for degenerate field free case are salvaged [A. F. Alexandrov, A. S. Bogdankevich, and A. A. Rukhadze, Principles of Plasma Electrodynamics (Springer-Verlag, Berlin/Heidelberg, 1984), p. 90].

  3. Predicting molecular scale skin-effect in electrochemical impedance due to anomalous subdiffusion mediated adsorption phenomenon

    NASA Astrophysics Data System (ADS)

    Kushagra, Arindam

    2016-02-01

    Anomalous subdiffusion governs the processes which are not energetically driven, on a molecular scale. This paper proposes a model to predict the response of electrochemical impedance due to such diffusion process. Previous works considered the use of fractional calculus to predict the impedance behaviour in response to the anomalous diffusion. Here, we have developed an expression which predicts the skin-effect, marked by an increase in the impedance with increasing frequency, in this regime. Negative inductances have also been predicted as a consequence of the inertial response of adsorbed species upon application of frequency-mediated perturbations. It might help the researchers in the fields of impedimetric sensors to choose the working frequency and those working in the field of batteries to choose the parameters, likewise. This work would shed some light into the molecular mechanisms governing the impedance when exposed to frequency-based perturbations like electromagnetic waves (microwaves to ionizing radiations) and in charge storage devices like batteries etc.

  4. Optical properties of metals: Infrared emissivity in the anomalous skin effect spectral region

    SciTech Connect

    Echániz, T.

    2014-09-07

    When the penetration depth of an electromagnetic wave in a metal is similar to the mean free path of the conduction electrons, the Drude classical theory is no longer satisfied and the skin effect becomes anomalous. Physical parameters of this theory for twelve metals were calculated and analyzed. The theory predicts an emissivity peak ε{sub peak} at room temperature in the mid-infrared for smooth surface metals that moves towards larger wavelengths as temperature decreases. Furthermore, the theory states that ε{sub peak} increases with the emission angle but its position, λ{sub peak}, is constant. Copper directional emissivity measurements as well as emissivity obtained using optical constants data confirm the predictions of the theory. Considering the relationship between the specularity parameter p and the sample roughness, it is concluded that p is not the simple parameter it is usually assumed to be. Quantitative comparison between experimental data and theoretical predictions shows that the specularity parameter can be equal to one for roughness values larger than those predicted. An exhaustive analysis of the experimental optical parameters shows signs of a reflectance broad peak in Cu, Al, Au, and Mo around the wavelength predicted by the theory for p = 1.

  5. Characteristics of anomalous skin effect and evolution of power absorption regions in a cylindrical radio frequency inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Ding, Z. F.; Sun, B.; Huo, W. G.

    2015-06-01

    In a low-pressure radio-frequency (13.56 MHz), inductively coupled argon plasma generated by a normal cylindrical rf coil, electric field, current density, and absorbed power density is calculated from magnetic field measured with a phase-resolved magnetic probe. The anomalous skin effect (ASE) for the cylindrical rf coil is compared to those previously reported for the planar and re-entrant cylindrical rf coils. Physical reasons for our observed characteristics of ASE are presented. With the increasing discharge power, the size and the number of negative and positive power absorption regions evolve into several distinct patterns. For the low discharge power (at 156.9 W), there is one area of positive and one area of negative power absorption in the radial direction. For the medium discharge power (279 W-683.5 W), there are two areas of negative and two areas of positive power absorption. For the even higher discharge power (above 803.5 W), the number of areas is the same as that of the medium discharge power, but the size of the inner positive and negative power absorption areas is approximately doubled and halved, respectively, while the outer positive and negative power absorption areas slightly shrinks. The evolution of positive and negative power absorption regions is explained as a result of electron thermal diffusion and the energy conversion between rf current and electric field. The spatial decays of electric field and current density are also elucidated by linking them with the positive and negative power absorption pattern.

  6. Characteristics of anomalous skin effect and evolution of power absorption regions in a cylindrical radio frequency inductively coupled plasma

    SciTech Connect

    Ding, Z. F.; Sun, B.; Huo, W. G.

    2015-06-15

    In a low-pressure radio-frequency (13.56 MHz), inductively coupled argon plasma generated by a normal cylindrical rf coil, electric field, current density, and absorbed power density is calculated from magnetic field measured with a phase-resolved magnetic probe. The anomalous skin effect (ASE) for the cylindrical rf coil is compared to those previously reported for the planar and re-entrant cylindrical rf coils. Physical reasons for our observed characteristics of ASE are presented. With the increasing discharge power, the size and the number of negative and positive power absorption regions evolve into several distinct patterns. For the low discharge power (at 156.9 W), there is one area of positive and one area of negative power absorption in the radial direction. For the medium discharge power (279 W–683.5 W), there are two areas of negative and two areas of positive power absorption. For the even higher discharge power (above 803.5 W), the number of areas is the same as that of the medium discharge power, but the size of the inner positive and negative power absorption areas is approximately doubled and halved, respectively, while the outer positive and negative power absorption areas slightly shrinks. The evolution of positive and negative power absorption regions is explained as a result of electron thermal diffusion and the energy conversion between rf current and electric field. The spatial decays of electric field and current density are also elucidated by linking them with the positive and negative power absorption pattern.

  7. Nonlocal Anomalous Hall Effect.

    PubMed

    Zhang, Steven S-L; Vignale, Giovanni

    2016-04-01

    The anomalous Hall (AH) effect is deemed to be a unique transport property of ferromagnetic metals, caused by the concerted action of spin polarization and spin-orbit coupling. Nevertheless, recent experiments have shown that the effect also occurs in a nonmagnetic metal (Pt) in contact with a magnetic insulator [yttrium iron garnet (YIG)], even when precautions are taken to ensure that there is no induced magnetization in the metal. We propose a theory of this effect based on the combined action of spin-dependent scattering from the magnetic interface and the spin-Hall effect in the bulk of the metal. At variance with previous theories, we predict the effect to be of first order in the spin-orbit coupling, just as the conventional anomalous Hall effect-the only difference being the spatial separation of the spin-orbit interaction and the magnetization. For this reason we name this effect the nonlocal anomalous Hall effect and predict that its sign will be determined by the sign of the spin-Hall angle in the metal. The AH conductivity that we calculate from our theory is in order of magnitude agreement with the measured values in Pt/YIG structures.

  8. Nonlocal Anomalous Hall Effect

    NASA Astrophysics Data System (ADS)

    Zhang, Steven S.-L.; Vignale, Giovanni

    2016-04-01

    The anomalous Hall (AH) effect is deemed to be a unique transport property of ferromagnetic metals, caused by the concerted action of spin polarization and spin-orbit coupling. Nevertheless, recent experiments have shown that the effect also occurs in a nonmagnetic metal (Pt) in contact with a magnetic insulator [yttrium iron garnet (YIG)], even when precautions are taken to ensure that there is no induced magnetization in the metal. We propose a theory of this effect based on the combined action of spin-dependent scattering from the magnetic interface and the spin-Hall effect in the bulk of the metal. At variance with previous theories, we predict the effect to be of first order in the spin-orbit coupling, just as the conventional anomalous Hall effect—the only difference being the spatial separation of the spin-orbit interaction and the magnetization. For this reason we name this effect the nonlocal anomalous Hall effect and predict that its sign will be determined by the sign of the spin-Hall angle in the metal. The AH conductivity that we calculate from our theory is in order of magnitude agreement with the measured values in Pt /YIG structures.

  9. Anomalous spin Josephson effect

    NASA Astrophysics Data System (ADS)

    Wang, Mei-Juan; Wang, Jun; Hao, Lei; Liu, Jun-Feng

    2016-10-01

    We report a theoretical study on the spin Josephson effect arising from the exchange coupling of the two ferromagnets (Fs), which are deposited on a two-dimensional (2D) time-reversal-invariant topological insulator. An anomalous spin supercurrent Js z˜sin(α +α0) is found to flow in between the two Fs and the ground state of the system is not limited to the magnetically collinear configuration (α =n π ,n is an integer) but determined by a controllable angle α0, where α is the crossed angle between the two F magnetizations. The angle α0 is the dynamic phase of the electrons traveling in between the two Fs and can be controlled electrically by a gate voltage. This anomalous spin Josephson effect, similar to the conventional φ0 superconductor junction, originates from the definite electron chirality of the helical edge states in the 2D topological insulator. These results indicate that the magnetic coupling in a topological system is different from the usual one in conventional materials.

  10. Nonlocal anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Zhang, Shulei; Vignale, Giovanni

    Anomalous Hall effect (AHE) is a distinctive transport property of ferromagnetic metals arising from spin orbit coupling (SOC) in concert with spontaneous spin polarization. Nonetheless, recent experiments have shown that the effect also appears in a nonmagnetic metal in contact with a magnetic insulator. The main puzzle lies in the apparent absence of spin polarized electrons in the non-magnetic metal. Here, we theoretically demonstrate that the scattering of electrons from a rough metal-insulator interface is generally spin-dependent, which results in mutual conversion between spin and charge currents flowing in the plane of the layer. It is the current-carrying spin polarized electrons and the spin Hall effect in the bulk of the metal layer that conspire to generate the AH current. This novel AHE differs from the conventional one only in the spatial separation of the SOC and the magnetization, so we name it as nonlocal AHE. In contrast to other previously proposed mechanisms (e.g., spin Hall AHE and magnetic proximity effect (MPE)), the nonlocal AHE appears on the first order of spin Hall angle and does not rely on the induced moments in the metal layer, which make it experimentally detectable by contrasting the AH current directions of two layered structures such as Pt/Cu/YIG and β -Ta/Cu/YIG (with a thin inserted Cu layer to eliminate the MPE). We predict that the directions of the AH currents in these two trilayers would be opposite since the spin Hall angles of Pt and β -Ta are of opposite signs. Work supported by NSF Grants DMR-1406568.

  11. Towards a Better Understanding of the Anomalous Hall Effect

    NASA Astrophysics Data System (ADS)

    Yue, Di; Jin, Xiaofeng

    2017-01-01

    Recent experimental efforts to identify the intrinsic and extrinsic contributions in the anomalous Hall effect are reviewed. Benefited from the experimental control of artificial impurity density in single crystalline magnetic thin films, a comprehensive physical picture of the anomalous Hall effect involving multiple competing scattering processes has been established. Some new insights into the microscopic mechanisms of the anomalous Hall effect are discussed.

  12. Precise Quantization of Anomalous Hall Effect

    NASA Astrophysics Data System (ADS)

    Bestwick, Andrew

    In the quantum anomalous Hall effect, electron transport in a magnetically-doped topological insulator takes place through chiral, dissipationless edge channels. In this talk, we discuss the behavior of a nearly ideal implementations of the effect in which the Hall resistance is within a part per 10,000 of its quantized value and the longitudinal resistivity can reach below 1 Ω per square. Nearly all Cr-doped topological insulator samples demonstrate extreme temperature dependence that is well-modeled by a small effective gap, allowing control over quantization with an unexpected magnetocaloric effect. We also discuss measurements of new device geometries and non-local resistances that identify the sources of dissipation that limit the effect. (Now at Rigetti Computing).

  13. Anomalous piezoresistance effect in ultrastrained silicon nanowires.

    PubMed

    Lugstein, A; Steinmair, M; Steiger, A; Kosina, H; Bertagnolli, E

    2010-08-11

    In this paper we demonstrate that under ultrahigh strain conditions p-type single crystal silicon nanowires possess an anomalous piezoresistance effect. The measurements were performed on vapor-liquid-solid (VLS) grown Si nanowires, monolithically integrated in a microelectro-mechanical loading module. The special setup enables the application of pure uniaxial tensile strain along the <111> growth direction of individual, 100 nm thick Si nanowires while simultaneously measuring the resistance of the nanowires. For low strain levels (nanowire elongation less than 0.8%), our measurements revealed the expected positive piezoresistance effect, whereas for ultrahigh strain levels a transition to anomalous negative piezoresistance was observed. For the maximum tensile strain of 3.5%, the resistance of the Si nanowires decreased by a factor of 10. Even at these high strain amplitudes, no fatigue failures are observed for several hundred loading cycles. The ability to fabricate single-crystal nanowires that are widely free of structural defects will it make possible to apply high strain without fracturing to other materials as well, therefore in any application where crystallinity and strain are important, the idea of making nanowires should be of a high value.

  14. Anomalous Josephson Hall effect in magnet/triplet superconductor junctions

    NASA Astrophysics Data System (ADS)

    Yokoyama, Takehito

    2015-11-01

    We investigate anomalous Hall effect in a magnet coupled to a triplet superconductor under phase gradient. It is found that the anomalous Hall supercurrent arises from the nontrivial structure of the magnetization. The magnetic structure manifested in the Hall supercurrent is characterized by even order terms of the exchange coupling, essentially different from that discussed in the context of anomalous Hall effect, reflecting the dissipationless nature of the supercurrent. We also discuss a possible candidate for magnetic structure to verify our prediction.

  15. Photonic versus electronic quantum anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Bleu, O.; Solnyshkov, D. D.; Malpuech, G.

    2017-03-01

    We derive the diagram of the topological phases accessible within a generic Hamiltonian describing quantum anomalous Hall effect for photons and electrons in honeycomb lattices in the presence of a Zeeman field and spin-orbit coupling (SOC). The two cases differ crucially by the winding number of their SOC, which is 1 for the Rashba SOC of electrons, and 2 for the photon SOC induced by the energy splitting between the TE and TM modes. As a consequence, the two models exhibit opposite Chern numbers ±2 at low field. Moreover, the photonic system shows a topological transition absent in the electronic case. If the photonic states are mixed with excitonic resonances to form interacting exciton-polaritons, the effective Zeeman field can be induced and controlled by a circularly polarized pump. This new feature allows an all-optical control of the topological phase transitions.

  16. Universal scaling of the anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoqian; Wang, Wei; Wang, Kejie; Niu, Wei; Lai, Bolin; Maltby, Nick; Yang, Mao; Gao, Ming; Liu, Wenqing; He, Liang; Zhang, Rong; Xu, Yongbing

    2017-04-01

    We have undertaken a detailed study of the magneto-transport properties of ultra-thin Fe films epitaxially grown on GaAs (1 0 0). A metal–semiconductor transition has been observed with a critical thickness of 1.25 nm, which was thought to be related to the thermally activated tunneling between metallic clusters. By fitting {ρ\\text{AH}} versus ρ xx2 with the TYJ equation (Tian et al 2009 Phys. Rev. Lett. 103 087206), we found that the magnetization is negligible for the scaling of the anomalous Hall effect in ultra-thin Fe films. Furthermore, the intrinsic term, which is acquired by the linear fitting of {ρ\\text{AH}} versus ρ xx2 , shows an obvious decrease when the film thickness drops below 1.25 nm, which was thought to be related to the fading of the Berry curvature in the ultra-thin film limit.

  17. Cyclotron maser using the anomalous Doppler effect

    NASA Astrophysics Data System (ADS)

    Didenko, A. N.; Borisov, A. R.; Fomenko, G. P.; Shlapakovskii, A. S.; Shtein, Iu. G.

    1983-11-01

    The operation of an anomalous-Doppler-effect cyclotron-resonance maser using a waveguide partially filled with dielectric as the slow-wave system is reported. The device investigated is similar to that of Didenko et al. (1983) and comprises a 300-mm-long 50-mm-o.d. 30-mm-i.d. waveguide with fabric-laminate dielectric, located 150 mm from the cathode in a 500-mm-long region of uniform 0-20-kG magnetic field, and a coaxial magnetic-insulation gun producing a 13-mm-i.d. 25-mm-o.d. hollow electron beam. Radiation at 12 + or - 1 mm wavelength and optimum power 20 MW is observed using hot-carrier detectors, with a clear peak in the power-versus-magnetic-field curve at about 6.4 kG.

  18. Quantum anomalous Hall effect in real materials

    NASA Astrophysics Data System (ADS)

    Zhang, Jiayong; Zhao, Bao; Zhou, Tong; Yang, Zhongqin

    2016-11-01

    Under a strong magnetic field, the quantum Hall (QH) effect can be observed in two-dimensional electronic gas systems. If the quantized Hall conductivity is acquired in a system without the need of an external magnetic field, then it will give rise to a new quantum state, the quantum anomalous Hall (QAH) state. The QAH state is a novel quantum state that is insulating in the bulk but exhibits unique conducting edge states topologically protected from backscattering and holds great potential for applications in low-power-consumption electronics. The realization of the QAH effect in real materials is of great significance. In this paper, we systematically review the theoretical proposals that have been brought forward to realize the QAH effect in various real material systems or structures, including magnetically doped topological insulators, graphene-based systems, silicene-based systems, two-dimensional organometallic frameworks, quantum wells, and functionalized Sb(111) monolayers, etc. Our paper can help our readers to quickly grasp the recent developments in this field. Project supported by the National Basic Research Program of China (Grant No. 2011CB921803), the National Natural Science Foundation of China (Grant No. 11574051), the Natural Science Foundation of Shanghai, China (Grant No. 14ZR1403400), and Fudan High-end Computing Center, China.

  19. In-plane magnetization-induced quantum anomalous Hall effect.

    PubMed

    Liu, Xin; Hsu, Hsiu-Chuan; Liu, Chao-Xing

    2013-08-23

    The quantum Hall effect can only be induced by an out-of-plane magnetic field for two-dimensional electron gases, and similarly, the quantum anomalous Hall effect has also usually been considered for systems with only out-of-plane magnetization. In the present work, we predict that the quantum anomalous Hall effect can be induced by in-plane magnetization that is not accompanied by any out-of-plane magnetic field. Two realistic two-dimensional systems, Bi2Te3 thin film with magnetic doping and HgMnTe quantum wells with shear strains, are presented and the general condition for the in-plane magnetization-induced quantum anomalous Hall effect is discussed based on the symmetry analysis. Nonetheless, an experimental setup is proposed to confirm this effect, the observation of which will pave the way to search for the quantum anomalous Hall effect in a wider range of materials.

  20. Linear Magnetization Dependence of the Intrinsic Anomalous Hall Effect

    SciTech Connect

    Zeng, C.; Yao, Y.; Niu, Q.; Weitering, Harm H

    2006-01-01

    The anomalous Hall effect is investigated experimentally and theoretically for ferromagnetic thin films of Mn{sub 5}Ge{sub 3}. We have separated the intrinsic and extrinsic contributions to the experimental anomalous Hall effect and calculated the intrinsic anomalous Hall conductivity from the Berry curvature of the Bloch states using first-principles methods. The intrinsic anomalous Hall conductivity depends linearly on the magnetization, which can be understood from the long-wavelength fluctuations of the spin orientation at finite temperatures. The quantitative agreement between theory and experiment is remarkably good, not only near 0 K but also at finite temperatures, up to about -240 K (0.8T{sub c}).

  1. Large anomalous Nernst effect in a skyrmion crystal

    NASA Astrophysics Data System (ADS)

    Mizuta, Yo Pierre; Ishii, Fumiyuki

    2016-06-01

    Thermoelectric properties of a model skyrmion crystal were theoretically investigated, and it was found that its large anomalous Hall conductivity, corresponding to large Chern numbers induced by its peculiar spin structure leads to a large transverse thermoelectric voltage through the anomalous Nernst effect. This implies the possibility of finding good thermoelectric materials among skyrmion systems, and thus motivates our quests for them by means of the first-principles calculations as were employed in this study.

  2. Large anomalous Nernst effect in a skyrmion crystal

    PubMed Central

    Mizuta, Yo Pierre; Ishii, Fumiyuki

    2016-01-01

    Thermoelectric properties of a model skyrmion crystal were theoretically investigated, and it was found that its large anomalous Hall conductivity, corresponding to large Chern numbers induced by its peculiar spin structure leads to a large transverse thermoelectric voltage through the anomalous Nernst effect. This implies the possibility of finding good thermoelectric materials among skyrmion systems, and thus motivates our quests for them by means of the first-principles calculations as were employed in this study. PMID:27306142

  3. Phenomenological Spin Transport Theory Driven by Anomalous Nernst Effect

    NASA Astrophysics Data System (ADS)

    Taniguchi, Tomohiro

    2016-07-01

    Several experimental efforts such as material investigation and structure improvement have been made recently to find a large anomalous Nernst effect in ferromagnetic metals. Here, we develop a theory of spin transport driven by the anomalous Nernst effect in a diffusive ferromagnetic/nonmagnetic multilayer. Starting from a phenomenological formula of a spin-dependent electric current, the theoretical formulas of electric voltage and spin torque generated by the anomalous Nernst effect are derived. The magnitude of the electric voltage generated from the spin current via the inverse spin Hall effect is on the order of 0.1 µV for currently available experimental parameter values. The temperature gradient necessary to switch the magnetization is quite larger than the typical experimental value. The separation of the contributions of the Seebeck and transverse spin Seebeck effects is also discussed.

  4. Anomalous Hall effect in YIG|Pt bilayers

    SciTech Connect

    Meyer, Sibylle Schlitz, Richard; Geprägs, Stephan; Opel, Matthias; Huebl, Hans; Goennenwein, Sebastian T. B.; Gross, Rudolf

    2015-03-30

    We measure the ordinary and the anomalous Hall effect in a set of yttrium iron garnet|platinum (YIG|Pt) bilayers via magnetization orientation dependent magnetoresistance experiments. Our data show that the presence of the ferrimagnetic insulator YIG leads to an anomalous Hall effect like voltage in Pt, which is sensitive to both Pt thickness and temperature. Interpretation of the experimental findings in terms of the spin Hall anomalous Hall effect indicates that the imaginary part of the spin mixing conductance G{sub i} plays a crucial role in YIG|Pt bilayers. In particular, our data suggest a sign change in G{sub i} between 10 K and 300 K. Additionally, we report a higher order Hall effect contribution, which appears in thin Pt films on YIG at low temperatures.

  5. Quantum anomalous Hall effect in magnetic insulator heterostructure.

    PubMed

    Xu, Gang; Wang, Jing; Felser, Claudia; Qi, Xiao-Liang; Zhang, Shou-Cheng

    2015-03-11

    On the basis of ab initio calculations, we predict that a monolayer of Cr-doped (Bi,Sb)2Te3 and GdI2 heterostructure is a quantum anomalous Hall insulator with a nontrivial band gap up to 38 meV. The principle behind our prediction is that the band inversion between two topologically trivial ferromagnetic insulators can result in a nonzero Chern number, which offers a better way to realize the quantum anomalous Hall state without random magnetic doping. In addition, a simple effective model is presented to describe the basic mechanism of spin polarized band inversion in this system. Moreover, we predict that 3D quantum anomalous Hall insulator could be realized in (Bi2/3Cr1/3)2Te3 /GdI2 superlattice.

  6. Anomalous tensoelectric effects in gallium arsenide tunnel diodes

    SciTech Connect

    Alekseeva, Z.M.; Vyatkin, A.P.; Krivorotov, N.P.; Shchegol', A.A.

    1988-02-01

    Anomalous tensoelectric phenomena induced in a tunnel p-n junction by a concentrated load and by hydrostatic compression were studied. The anomalous tensoelectric effects are caused by the action of concentrators of mechanical stresses in the vicinity of the p-n junction, giving rise to local microplastic strain. Under the conditions of hydrostatic compression prolate inclusions approx.100-200 A long play the role of concentrators. Analysis of irreversible changes in the current-voltage characteristics of tunnel p-n junctions made it possible to separate the energy levels of the defects produced with plastic strain of gallium arsenide.

  7. Fast plasma heating by anomalous and inertial resistivity effects

    NASA Technical Reports Server (NTRS)

    Duijveman, A.; Hoyng, P.; Ionson, J. A.

    1981-01-01

    Fast plasma heating by anomalous and inertial resistivity effects is described. A small fraction of the plasma contains strong currents that run parallel to the magnetic field and are driven by an exponentiating electric field. The anomalous character of the current dissipation is caused by the excitation of electrostatic ion cyclotron and/or ion acoustic waves. The role of resistivity due to geometrical effects is considered. Through the use of a marginal stability analysis, equations for the average electron and ion temperatures are derived and numerically solved. The evolution of the plasma is described as a path in the drift velocity diagram, in which the drift velocity is plotted as a function of the electron to ion temperature ratio.

  8. Nontrivial anomalous Hall effect in ultrathin Pt/permalloy bilayers

    NASA Astrophysics Data System (ADS)

    Zhang, Yanqing; Shan, Rong

    2015-03-01

    Anomalous Hall effect of Pt (2.5 nm)/permalloy bilayers with the thickness tPy = 0.6 ~10 nm; Pt/permalloy (2.2 nm) bilayers with the thickness tPt = 1.5 ~10 nm and Pt (2.5 nm)/permalloy (2.2 nm) bilayers with the post-annealing temperature 100 ~500° grown on MgO (001) substrates are investigated. The Pt/permalloy bilayer shows distinguished performance from the single permalloy layer due to the interfacial influence. Effective magnetic anisotropy of the bilayer with tPy <2.2 nm turns to be perpendicular to the film plane and it increases with decreasing measured temperature. More interestingly, the anomalous Hall effect is also greatly enhanced in these Pt/permalloy bilayers, comparing with that in bulk permalloy. The parameters presenting skew scattering, side jump and intrinsic contribution become extremely large, indicating a strong influence of spin orbit coupling coming from Pt/permalloy interface on the anomalous Hall effect.

  9. Test of an anomalous electromagnetic effect

    NASA Astrophysics Data System (ADS)

    Bartlett, D. F.; Maglic, Steven

    1990-10-01

    Sansbury has suggested and measured a new electromagnetic attraction between a current and a static charge. We have searched in vain for this interaction. The sensitivity of our measurement is roughly 5 times higher than that of the experiment in which the effect was originally seen.

  10. Normal and anomalous Doppler effects in periodic waveguide cyclotron maser

    SciTech Connect

    Korol, M.; Jerby, E.

    1995-12-31

    A linear analysis of the periodic-waveguide cyclotron (PWC) maser shows that the PWC interaction with fast-waves possesses properties of the known anomalous Doppler resonance interaction if the wave impedance of the resonant spatial harmonic, Z{sub n}, is much smaller than the free space impedance, i.e. if Z{sub n} {much_lt} Z{sub 0}. The feasibility of a fast-wave PWC interaction in a low impedance waveguide is examined theoretically in this paper. A practical scheme of a slotted-waveguide PWC operating in the fundamental harmonic near cutoff is proposed for a future experiment. The possible advantages of the quasi-anomalous Doppler effect in the fast-wave-PWC operating regime are the alleviation of the initial electron rotation and a high-efficiency operation.

  11. Quantum anomalous Hall effect in stable dumbbell stanene

    NASA Astrophysics Data System (ADS)

    Zhang, Huisheng; Zhang, Jiayong; Zhao, Bao; Zhou, Tong; Yang, Zhongqin

    2016-02-01

    Topological property of the dumbbell (DB) stanene, more stable than the stanene with a honeycomb lattice, is investigated by using ab initio methods. The magnetic DB stanene demonstrates an exotic quantum anomalous Hall (QAH) effect due to inversion of the Sn spin-up px,y and spin-down pz states. The QAH gap is found to be opened at Γ point rather than the usual K and K' points, beneficial to observe the effect in experiments. When a 3% tensile strain is applied, a large nontrivial gap (˜50 meV) is achieved. Our results provide another lighthouse for realizing QAH effects in two-dimensional systems.

  12. Enhanced thermoelectric performance and anomalous seebeck effects in topological insulators.

    PubMed

    Xu, Yong; Gan, Zhongxue; Zhang, Shou-Cheng

    2014-06-06

    Improving the thermoelectric figure of merit zT is one of the greatest challenges in material science. The recent discovery of topological insulators (TIs) offers new promise in this prospect. In this work, we demonstrate theoretically that zT is strongly size dependent in TIs, and the size parameter can be tuned to enhance zT to be significantly greater than 1. Furthermore, we show that the lifetime of the edge states in TIs is strongly energy dependent, leading to large and anomalous Seebeck effects with an opposite sign to the Hall effect. These striking properties make TIs a promising material for thermoelectric science and technology.

  13. Anomalous Hall Effect in a Feromagnetic Rare-Earth Cobalite

    NASA Technical Reports Server (NTRS)

    Samoilov, A. V.; Yeh, N. C.; Vasquez, R. P.

    1996-01-01

    Rare-Earth manganites and cobalites with the perovskite structure have been a subject of great recent interest because their electrical resistance changes significantly when a magnetic field is applied...we have studied the Hall effect in thin film La(sub 0.5)Ca(sub 0.5)CoO(sub 3) material and have obtained convincing evidence fo the so called anomalous Hall effect, typical for magnetic metals...Our results suggest that near the ferromagnetic ordering temperature, the dominant electron scattering mechanism is the spin fluctuation.

  14. Quantum anomalous Hall effect in topological insulator memory

    SciTech Connect

    Jalil, Mansoor B. A.; Tan, S. G.; Siu, Z. B.

    2015-05-07

    We theoretically investigate the quantum anomalous Hall effect (QAHE) in a magnetically coupled three-dimensional-topological insulator (3D-TI) system. We apply the generalized spin-orbit coupling Hamiltonian to obtain the Hall conductivity σ{sup xy} of the system. The underlying topology of the QAHE phenomenon is then analyzed to show the quantization of σ{sup xy} and its relation to the Berry phase of the system. Finally, we analyze the feasibility of utilizing σ{sup xy} as a memory read-out in a 3D-TI based memory at finite temperatures, with comparison to known magnetically doped 3D-TIs.

  15. Large anomalous Hall effect in a half-Heusler antiferromagnet

    NASA Astrophysics Data System (ADS)

    Suzuki, T.; Chisnell, R.; Devarakonda, A.; Liu, Y.-T.; Feng, W.; Xiao, D.; Lynn, J. W.; Checkelsky, J. G.

    2016-12-01

    The quantum mechanical (Berry) phase of the electronic wavefunction plays a critical role in the anomalous and spin Hall effects, including their quantized limits. While progress has been made in understanding these effects in ferromagnets, less is known in antiferromagnetic systems. Here we present a study of antiferromagnet GdPtBi, whose electronic structure is similar to that of the topologically non-trivial HgTe (refs ,,), and where the Gd ions offer the possibility to tune the Berry phase via control of the spin texture. We show that this system supports an anomalous Hall angle ΘAH > 0.1, comparable to the largest observed in bulk ferromagnets and significantly larger than in other antiferromagnets. Neutron scattering measurements and electronic structure calculations suggest that this effect originates from avoided crossing or Weyl points that develop near the Fermi level due to a breaking of combined time-reversal and lattice symmetries. Berry phase effects associated with such symmetry breaking have recently been explored in kagome networks; our results extend this to half-Heusler systems with non-trivial band topology. The magnetic textures indicated here may also provide pathways towards realizing the topological insulating and semimetallic states predicted in this material class.

  16. Nonlinear dynamics induced anomalous Hall effect in topological insulators.

    PubMed

    Wang, Guanglei; Xu, Hongya; Lai, Ying-Cheng

    2016-01-28

    We uncover an alternative mechanism for anomalous Hall effect. In particular, we investigate the magnetisation dynamics of an insulating ferromagnet (FM) deposited on the surface of a three-dimensional topological insulator (TI), subject to an external voltage. The spin-polarised current on the TI surface induces a spin-transfer torque on the magnetisation of the top FM while its dynamics can change the transmission probability of the surface electrons through the exchange coupling and hence the current. We find a host of nonlinear dynamical behaviors including multistability, chaos, and phase synchronisation. Strikingly, a dynamics mediated Hall-like current can arise, which exhibits a nontrivial dependence on the channel conductance. We develop a physical understanding of the mechanism that leads to the anomalous Hall effect. The nonlinear dynamical origin of the effect stipulates that a rich variety of final states exist, implying that the associated Hall current can be controlled to yield desirable behaviors. The phenomenon can find applications in Dirac-material based spintronics.

  17. Nonlinear dynamics induced anomalous Hall effect in topological insulators

    NASA Astrophysics Data System (ADS)

    Wang, Guanglei; Xu, Hongya; Lai, Ying-Cheng

    2016-01-01

    We uncover an alternative mechanism for anomalous Hall effect. In particular, we investigate the magnetisation dynamics of an insulating ferromagnet (FM) deposited on the surface of a three-dimensional topological insulator (TI), subject to an external voltage. The spin-polarised current on the TI surface induces a spin-transfer torque on the magnetisation of the top FM while its dynamics can change the transmission probability of the surface electrons through the exchange coupling and hence the current. We find a host of nonlinear dynamical behaviors including multistability, chaos, and phase synchronisation. Strikingly, a dynamics mediated Hall-like current can arise, which exhibits a nontrivial dependence on the channel conductance. We develop a physical understanding of the mechanism that leads to the anomalous Hall effect. The nonlinear dynamical origin of the effect stipulates that a rich variety of final states exist, implying that the associated Hall current can be controlled to yield desirable behaviors. The phenomenon can find applications in Dirac-material based spintronics.

  18. Anomalous photoelectric effect of a polycrystalline topological insulator film.

    PubMed

    Zhang, Hongbin; Yao, Jiandong; Shao, Jianmei; Li, Hai; Li, Shuwei; Bao, Dinghua; Wang, Chengxin; Yang, Guowei

    2014-07-29

    A topological insulator represents a new state of quantum matter that possesses an insulating bulk band gap as well as a spin-momentum-locked Dirac cone on the surface that is protected by time-reversal symmetry. Photon-dressed surface states and light-induced surface photocurrents have been observed in topological insulators. Here, we report experimental observations of an anomalous photoelectric effect in thin films of Bi2Te3, a polycrystalline topological insulator. Under illumination with non-polarised light, transport measurements reveal that the resistance of the topological surface states suddenly increases when the polycrystalline film is illuminated. The resistance variation is positively dependent on the light intensity but has no relation to the applied electric field; this finding can be attributed to the gap opening of the surface Dirac cone. This observation of an anomalous photoelectric effect in polycrystalline topological insulators offers exciting opportunities for the creation of photodetectors with an unusually broad spectral range. Moreover, polycrystalline topological insulator films provide an attractive material platform for exploring the nature and practical application of topological insulators.

  19. Anomalous Photoelectric Effect of a Polycrystalline Topological Insulator Film

    PubMed Central

    Zhang, Hongbin; Yao, Jiandong; Shao, Jianmei; Li, Hai; Li, Shuwei; Bao, Dinghua; Wang, Chengxin; Yang, Guowei

    2014-01-01

    A topological insulator represents a new state of quantum matter that possesses an insulating bulk band gap as well as a spin-momentum-locked Dirac cone on the surface that is protected by time-reversal symmetry. Photon-dressed surface states and light-induced surface photocurrents have been observed in topological insulators. Here, we report experimental observations of an anomalous photoelectric effect in thin films of Bi2Te3, a polycrystalline topological insulator. Under illumination with non-polarised light, transport measurements reveal that the resistance of the topological surface states suddenly increases when the polycrystalline film is illuminated. The resistance variation is positively dependent on the light intensity but has no relation to the applied electric field; this finding can be attributed to the gap opening of the surface Dirac cone. This observation of an anomalous photoelectric effect in polycrystalline topological insulators offers exciting opportunities for the creation of photodetectors with an unusually broad spectral range. Moreover, polycrystalline topological insulator films provide an attractive material platform for exploring the nature and practical application of topological insulators. PMID:25069391

  20. Anomalously large Born effective charges in cubic WO3

    NASA Astrophysics Data System (ADS)

    Detraux, F.; Ghosez, Ph.; Gonze, X.

    1997-07-01

    Within density-functional theory, we compute the Born effective charges of tungsten trioxyde in its reference cubic phase (defect-perovskite structure). For the tungsten atom, the effective charge tensor is isotropic, with Z*W=+12.51. For the oxygen atoms, the two independent components of the tensor, corresponding, respectively, to a displacement of the atom parallel or perpendicular to the W-O bond, have the values Z*O||=-9.13 and Z*O⊥=-1.68. Z*W and Z*O|| are anomalously large with respect to the nominal ionic charges (+6 on W and -2 on O), but compatible with the Born effective charges found in related ABO3-perovskite compounds.

  1. Investigating dissipation in the quantum anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Fox, Eli; Bestwick, Andrew; Goldhaber-Gordon, David; Feng, Yang; Ou, Yunbo; He, Ke; Wang, Yayu; Xue, Qi-Kun; Kou, Xufeng; Pan, Lei; Wang, Kang

    In the quantum anomalous Hall effect, a magnetic exchange gap in a 3D topological insulator gives rise to dissipationless chiral edge states. Though the effect has recently been realized in a family of ferromagnetically-doped (Bi,Sb)2Te3 topological insulator thin films, experiments to date have found non-vanishing longitudinal resistance, contrary to initial theoretical expectations. Proposed sources of this dissipation include extra gapless or activated quasi-helical edge states, thermally activated 2D conduction, and variable-range hopping. Here, we discuss transport measurements of Corbino disk and non-local geometries to identify the mechanism of non-ideal behavior. This work supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award No. 19-7503.

  2. Influence of disorder on anomalous Hall effect for Heusler compounds

    NASA Astrophysics Data System (ADS)

    Vilanova Vidal, E.; Schneider, H.; Jakob, G.

    2011-05-01

    The anomalous Hall effect (AHE) is a long known but still not fully understood transport effect. Most theory papers focus on the influence of one particular contribution to the AHE. Actual measured experimental data, however, often are not in accord with idealized assumptions. In this work we discuss the data analysis for materials with low residual resistivity ratios. As prototypical materials we study half metallic Heusler compounds. Here the influence of defects and disorder is apparent in a material with a complex topology of the Fermi surface. Using films of different degree of disorder, we show how different scattering mechanisms can be separated. For Co2FeSi0.6Al0.4 and Co2FeGa0.5Ge0.5 the AHE induced by B2-type disorder and temperature-dependent scattering is positive, while DO3-type disorder and possible intrinsic contributions possess a negative sign.

  3. Precise quantization of anomalous Hall effect near zero magnetic field

    SciTech Connect

    Bestwick, A. J.; Fox, E. J.; Kou, Xufeng; Pan, Lei; Wang, Kang L.; Goldhaber-Gordon, D.

    2015-05-04

    In this study, we report a nearly ideal quantum anomalous Hall effect in a three-dimensional topological insulator thin film with ferromagnetic doping. Near zero applied magnetic field we measure exact quantization in the Hall resistance to within a part per 10,000 and a longitudinal resistivity under 1 Ω per square, with chiral edge transport explicitly confirmed by nonlocal measurements. Deviations from this behavior are found to be caused by thermally activated carriers, as indicated by an Arrhenius law temperature dependence. Using the deviations as a thermometer, we demonstrate an unexpected magnetocaloric effect and use it to reach near-perfect quantization by cooling the sample below the dilution refrigerator base temperature in a process approximating adiabatic demagnetization refrigeration.

  4. Precise quantization of anomalous Hall effect near zero magnetic field

    NASA Astrophysics Data System (ADS)

    Bestwick, Andrew; Fox, Eli; Kou, Xufeng; Pan, Lei; Wang, Kang; Goldhaber-Gordon, David

    2015-03-01

    The quantum anomalous Hall effect (QAHE) has recently been of great interest due to its recent experimental realization in thin films of Cr-doped (Bi, Sb)2Te3, a ferromagnetic 3D topological insulator. The presence of ferromagnetic exchange breaks time-reversal symmetry, opening a gap in the surface states, but gives rise to dissipationless chiral conduction at the edge of a magnetized film. Ideally, this leads to vanishing longitudinal resistance and Hall resistance quantized to h /e2 , where h is Planck's constant and e is the electron charge, but perfect quantization has so far proved elusive. Here, we study the QAHE in the limit of zero applied magnetic field, and measure Hall resistance quantized to within one part per 10,000. Deviation from quantization is due primarily to thermally activated carriers, which can be nearly eliminated through adiabatic demagnetization cooling. This result demonstrates an important step toward dissipationless electron transport in technologically relevant conditions.

  5. Thickness Dependence of the Quantum Anomalous Hall Effect in Magnetic Topological Insulator Films.

    PubMed

    Feng, Xiao; Feng, Yang; Wang, Jing; Ou, Yunbo; Hao, Zhenqi; Liu, Chang; Zhang, Zuocheng; Zhang, Liguo; Lin, Chaojing; Liao, Jian; Li, Yongqing; Wang, Li-Li; Ji, Shuai-Hua; Chen, Xi; Ma, Xucun; Zhang, Shou-Cheng; Wang, Yayu; He, Ke; Xue, Qi-Kun

    2016-08-01

    The evolution of the quantum anomalous Hall effect with the thickness of Cr-doped (Bi,Sb)2 Te3 magnetic topological insulator films is studied, revealing how the effect is caused by the interplay of the surface states, band-bending, and ferromagnetic exchange energy. Homogeneity in ferromagnetism is found to be the key to high-temperature quantum anomalous Hall material.

  6. Quantum anomalous Hall effect in stanene on a nonmagnetic substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Huisheng; Zhou, Tong; Zhang, Jiayong; Zhao, Bao; Yao, Yugui; Yang, Zhongqin

    2016-12-01

    Since the quantum anomalous Hall (QAH) effect was realized in magnetic topological insulators, research on the effect has become a hot topic. The very harsh realizing requirements of the effect in experiments, however, hinder its practical applications. Based on ab initio methods, we find that nonmagnetic Pb I2 films are ideal substrates for the two-dimensional honeycomb stanene. The QAH effect with a pretty large band gap (up to 90 meV) can be achieved in the functionalized stanene /Pb I2 heterostructure. Despite van der Waals interactions in the heterostructure, band inversions are found to be happening between Sn (s and px ,y ) and Pb (px ,y) orbitals, playing a key role in determining the nontrivial topology and the large band gap of the system. Having no magnetic atoms is imperative to triggering the QAH effect. A very stable rudimentary device having QAH effects is proposed based on the Sn /Pb I2 heterostructure. Our results demonstrate that QAH effects can be easily realized in the Sn /Pb I2 heterostructures in experiments.

  7. Quantum anomalous Hall effect in magnetic topological insulators

    SciTech Connect

    Wang, Jing; Lian, Biao; Zhang, Shou -Cheng

    2015-08-25

    The search for topologically non-trivial states of matter has become an important goal for condensed matter physics. Here, we give a theoretical introduction to the quantum anomalous Hall (QAH) effect based on magnetic topological insulators in two-dimensions (2D) and three-dimensions (3D). In 2D topological insulators, magnetic order breaks the symmetry between the counter-propagating helical edge states, and as a result, the quantum spin Hall effect can evolve into the QAH effect. In 3D, magnetic order opens up a gap for the topological surface states, and chiral edge state has been predicted to exist on the magnetic domain walls. We present the phase diagram in thin films of a magnetic topological insulator and review the basic mechanism of ferromagnetic order in magnetically doped topological insulators. We also review the recent experimental observation of the QAH effect. Furthermore, we discuss more recent theoretical work on the coexistence of the helical and chiral edge states, multi-channel chiral edge states, the theory of the plateau transition, and the thickness dependence in the QAH effect.

  8. Chiral vortical and magnetic effects in the anomalous transport model

    NASA Astrophysics Data System (ADS)

    Sun, Yifeng; Ko, Che Ming

    2017-03-01

    We extend our recent study of chiral magnetic effect in relativistic heavy ion collisions based on an anomalous transport model by including also the chiral vortical effect. We find that although vorticities in the chirally restored quark matter, which result from the large angular momentum in noncentral collisions, can generate an axial charge dipole moment in the transverse plane of a heavy ion collision, it does not produce a difference in the eccentricities of negatively and positively charged particles. As a result, including the chiral vortical effect alone cannot lead to a splitting between the elliptic flows of negatively and positively charged particles. On the other hand, negatively and positively charged particles do develop a splitting in their elliptic flows if the effect due to a strong and long-lived magnetic field is also included. However, to have a positive slope in the dependence of the elliptic flow splitting on the charge asymmetry of the quark matter, as seen in experiments, requires the neglect of the effect of the Lorentz force. In this case, an elliptic flow splitting appears even at vanishing charge asymmetry.

  9. Quantum anomalous Hall effect in magnetic topological insulators

    DOE PAGES

    Wang, Jing; Lian, Biao; Zhang, Shou -Cheng

    2015-08-25

    The search for topologically non-trivial states of matter has become an important goal for condensed matter physics. Here, we give a theoretical introduction to the quantum anomalous Hall (QAH) effect based on magnetic topological insulators in two-dimensions (2D) and three-dimensions (3D). In 2D topological insulators, magnetic order breaks the symmetry between the counter-propagating helical edge states, and as a result, the quantum spin Hall effect can evolve into the QAH effect. In 3D, magnetic order opens up a gap for the topological surface states, and chiral edge state has been predicted to exist on the magnetic domain walls. We presentmore » the phase diagram in thin films of a magnetic topological insulator and review the basic mechanism of ferromagnetic order in magnetically doped topological insulators. We also review the recent experimental observation of the QAH effect. Furthermore, we discuss more recent theoretical work on the coexistence of the helical and chiral edge states, multi-channel chiral edge states, the theory of the plateau transition, and the thickness dependence in the QAH effect.« less

  10. Quantum anomalous Hall effect in ferromagnetic transition metal halides

    NASA Astrophysics Data System (ADS)

    Huang, Chengxi; Zhou, Jian; Wu, Haiping; Deng, Kaiming; Jena, Puru; Kan, Erjun

    2017-01-01

    The quantum anomalous Hall (QAH) effect is a novel topological spintronic phenomenon arising from inherent magnetization and spin-orbit coupling. Various theoretical and experimental efforts have been devoted in search of intrinsic QAH insulators. However, up to now, it has only been observed in Cr or V doped (Bi,Sb ) 2T e3 film in experiments with very low working temperature. Based on the successful synthesis of transition metal halides, we use first-principles calculations to predict that the Ru I3 monolayer is an intrinsic ferromagnetic QAH insulator with a topologically nontrivial global band gap of 11 meV. This topologically nontrivial band gap at the Fermi level is due to its crystal symmetry, thus the QAH effect is robust. Its Curie temperature, estimated to be ˜360 K using Monte Carlo simulation, is above room temperature and higher than most two-dimensional ferromagnetic thin films. The inclusion of Hubbard U in the Ru-d electrons does not affect this result. We also discuss the manipulation of its exchange energy and nontrivial band gap by applying in-plane strain. Our work adds an experimentally feasible member to the QAH insulator family, which is expected to have broad applications in nanoelectronics and spintronics.

  11. Concepts of ferrovalley material and anomalous valley Hall effect.

    PubMed

    Tong, Wen-Yi; Gong, Shi-Jing; Wan, Xiangang; Duan, Chun-Gang

    2016-12-16

    Valleytronics rooted in the valley degree of freedom is of both theoretical and technological importance as it offers additional opportunities for information storage, as well as electronic, magnetic and optical switches. In analogy to ferroelectric materials with spontaneous charge polarization, or ferromagnetic materials with spontaneous spin polarization, here we introduce a new member of ferroic family, that is, a ferrovalley material with spontaneous valley polarization. Combining a two-band k·p model with first-principles calculations, we show that 2H-VSe2 monolayer, where the spin-orbit coupling coexists with the intrinsic exchange interaction of transition-metal d electrons, is such a room-temperature ferrovalley material. We further predict that such system could demonstrate many distinctive properties, for example, chirality-dependent optical band gap and, more interestingly, anomalous valley Hall effect. On account of the latter, functional devices based on ferrovalley materials, such as valley-based nonvolatile random access memory and valley filter, are contemplated for valleytronic applications.

  12. Cluster multipole theory for anomalous Hall effect in antiferromagnets

    NASA Astrophysics Data System (ADS)

    Suzuki, M.-T.; Koretsune, T.; Ochi, M.; Arita, R.

    2017-03-01

    We introduce a cluster extension of multipole moments to discuss the anomalous Hall effect (AHE) in both ferromagnetic (FM) and antiferromagnetic (AFM) states in a unified framework. We first derive general symmetry requirements for the AHE in the presence or absence of the spin-orbit coupling by considering the symmetry of the Berry curvature in k space. The cluster multipole (CMP) moments are then defined to quantify the macroscopic magnetization in noncollinear AFM states as a natural generalization of the magnetization in FM states. We identify the macroscopic CMP order which induces the AHE. The theoretical framework is applied to the noncollinear AFM states of Mn3Ir , for which an AHE was predicted in a first-principles calculation, and Mn3Z (Z =Sn ,Ge ), for which a large AHE was recently discovered experimentally. We further compare the AHE in Mn3Z and bcc Fe in terms of the CMP. We show that the AHE in Mn3Z is characterized by the magnetization of a cluster octupole moment in the same manner as that in bcc Fe characterized by the magnetization of the dipole moment.

  13. Concepts of ferrovalley material and anomalous valley Hall effect

    PubMed Central

    Tong, Wen-Yi; Gong, Shi-Jing; Wan, Xiangang; Duan, Chun-Gang

    2016-01-01

    Valleytronics rooted in the valley degree of freedom is of both theoretical and technological importance as it offers additional opportunities for information storage, as well as electronic, magnetic and optical switches. In analogy to ferroelectric materials with spontaneous charge polarization, or ferromagnetic materials with spontaneous spin polarization, here we introduce a new member of ferroic family, that is, a ferrovalley material with spontaneous valley polarization. Combining a two-band k·p model with first-principles calculations, we show that 2H-VSe2 monolayer, where the spin–orbit coupling coexists with the intrinsic exchange interaction of transition-metal d electrons, is such a room-temperature ferrovalley material. We further predict that such system could demonstrate many distinctive properties, for example, chirality-dependent optical band gap and, more interestingly, anomalous valley Hall effect. On account of the latter, functional devices based on ferrovalley materials, such as valley-based nonvolatile random access memory and valley filter, are contemplated for valleytronic applications. PMID:27982088

  14. Concepts of ferrovalley material and anomalous valley Hall effect

    NASA Astrophysics Data System (ADS)

    Tong, Wen-Yi; Gong, Shi-Jing; Wan, Xiangang; Duan, Chun-Gang

    2016-12-01

    Valleytronics rooted in the valley degree of freedom is of both theoretical and technological importance as it offers additional opportunities for information storage, as well as electronic, magnetic and optical switches. In analogy to ferroelectric materials with spontaneous charge polarization, or ferromagnetic materials with spontaneous spin polarization, here we introduce a new member of ferroic family, that is, a ferrovalley material with spontaneous valley polarization. Combining a two-band k.p model with first-principles calculations, we show that 2H-VSe2 monolayer, where the spin-orbit coupling coexists with the intrinsic exchange interaction of transition-metal d electrons, is such a room-temperature ferrovalley material. We further predict that such system could demonstrate many distinctive properties, for example, chirality-dependent optical band gap and, more interestingly, anomalous valley Hall effect. On account of the latter, functional devices based on ferrovalley materials, such as valley-based nonvolatile random access memory and valley filter, are contemplated for valleytronic applications.

  15. Observation of anomalous Hall effect in a non-magnetic two-dimensional electron system

    PubMed Central

    Maryenko, D.; Mishchenko, A. S.; Bahramy, M. S.; Ernst, A.; Falson, J.; Kozuka, Y.; Tsukazaki, A.; Nagaosa, N.; Kawasaki, M.

    2017-01-01

    Anomalous Hall effect, a manifestation of Hall effect occurring in systems without time-reversal symmetry, has been mostly observed in ferromagnetically ordered materials. However, its realization in high-mobility two-dimensional electron system remains elusive, as the incorporation of magnetic moments deteriorates the device performance compared to non-doped structure. Here we observe systematic emergence of anomalous Hall effect in various MgZnO/ZnO heterostructures that exhibit quantum Hall effect. At low temperatures, our nominally non-magnetic heterostructures display an anomalous Hall effect response similar to that of a clean ferromagnetic metal, while keeping a large anomalous Hall effect angle θAHE≈20°. Such a behaviour is consistent with Giovannini–Kondo model in which the anomalous Hall effect arises from the skew scattering of electrons by localized paramagnetic centres. Our study unveils a new aspect of many-body interactions in two-dimensional electron systems and shows how the anomalous Hall effect can emerge in a non-magnetic system. PMID:28300133

  16. Observation of anomalous Hall effect in a non-magnetic two-dimensional electron system

    NASA Astrophysics Data System (ADS)

    Maryenko, D.; Mishchenko, A. S.; Bahramy, M. S.; Ernst, A.; Falson, J.; Kozuka, Y.; Tsukazaki, A.; Nagaosa, N.; Kawasaki, M.

    2017-03-01

    Anomalous Hall effect, a manifestation of Hall effect occurring in systems without time-reversal symmetry, has been mostly observed in ferromagnetically ordered materials. However, its realization in high-mobility two-dimensional electron system remains elusive, as the incorporation of magnetic moments deteriorates the device performance compared to non-doped structure. Here we observe systematic emergence of anomalous Hall effect in various MgZnO/ZnO heterostructures that exhibit quantum Hall effect. At low temperatures, our nominally non-magnetic heterostructures display an anomalous Hall effect response similar to that of a clean ferromagnetic metal, while keeping a large anomalous Hall effect angle θAHE~20°. Such a behaviour is consistent with Giovannini-Kondo model in which the anomalous Hall effect arises from the skew scattering of electrons by localized paramagnetic centres. Our study unveils a new aspect of many-body interactions in two-dimensional electron systems and shows how the anomalous Hall effect can emerge in a non-magnetic system.

  17. Magnetic Topological Insulators and Quantum Anomalous Hall Effect

    NASA Astrophysics Data System (ADS)

    Kou, Xufeng

    The engineering of topological surface states is a key to realize applicable devices based on topological insulators (TIs). Among various proposals, introducing magnetic impurities into TIs has been proven to be an effective way to open a surface gap and integrate additional ferromagnetism with the original topological order. In this Dissertation, we study both the intrinsic electrical and magnetic properties of the magnetic TI thin films grown by molecular beam epitaxy. By doping transition element Cr into the host tetradymite-type V-VI semiconductors, we achieve robust ferromagnetic order with a strong perpendicular magnetic anisotropy. With additional top-gating capability, we realize the electric-field-controlled ferromagnetism in the magnetic TI systems, and demonstrate such magneto-electric effects can be effectively manipulated, depending on the interplays between the band topology, magnetic exchange coupling, and structural engineering. Most significantly, we report the observation of quantum anomalous Hall effect (QAHE) in the Cr-doped (BiSb)2Te3 samples where dissipationless chiral edge conduction is realized in the macroscopic millimeter-size devices without the presence of any external magnetic field, and the stability of the quantized Hall conductance of e2/h is well-maintained as the film thickness varies across the 2D hybridization limit. With additional quantum confinement, we discover the metal-to-insulator switching between two opposite QAHE states, and reveal the universal QAHE phase diagram in the thin magnetic TI samples. In addition to the uniform magnetic TIs, we further investigate the TI/Cr-doped TI bilayer structures prepared by the modulation-doped growth method. By controlling the magnetic interaction profile, we observe the Dirac hole-mediated ferromagnetism and develop an effective way to manipulate its strength. Besides, the giant spin-orbit torque in such magnetic TI-based heterostructures enables us to demonstrate the current

  18. Skin thickness effects on in vivo LXRF

    SciTech Connect

    Preiss, I.L.; Washington, W. II

    1995-12-31

    The analysis of lead concentration in bone utilizing LXRF can be adversely effected by overlying issue. A quantitative measure of the attenuation of the 10.5 keV Pb L a x-ray signal by skin and skin equivalent plastic has been conducted. Concentration ranges in plaster of Paris and goat bone from 7 to 90 ppm with attenuators of Lucite{reg_sign} and pig skin were examined. It is concluded that no quantitative or semi quantitative analysis can be achieved if overlying sue thickness exceeds 3 mm for Ph concentrations of less than 30 porn Ph in bone.

  19. Large anomalous Hall effect in a non-collinear antiferromagnet at room temperature.

    PubMed

    Nakatsuji, Satoru; Kiyohara, Naoki; Higo, Tomoya

    2015-11-12

    In ferromagnetic conductors, an electric current may induce a transverse voltage drop in zero applied magnetic field: this anomalous Hall effect is observed to be proportional to magnetization, and thus is not usually seen in antiferromagnets in zero field. Recent developments in theory and experiment have provided a framework for understanding the anomalous Hall effect using Berry-phase concepts, and this perspective has led to predictions that, under certain conditions, a large anomalous Hall effect may appear in spin liquids and antiferromagnets without net spin magnetization. Although such a spontaneous Hall effect has now been observed in a spin liquid state, a zero-field anomalous Hall effect has hitherto not been reported for antiferromagnets. Here we report empirical evidence for a large anomalous Hall effect in an antiferromagnet that has vanishingly small magnetization. In particular, we find that Mn3Sn, an antiferromagnet that has a non-collinear 120-degree spin order, exhibits a large anomalous Hall conductivity of around 20 per ohm per centimetre at room temperature and more than 100 per ohm per centimetre at low temperatures, reaching the same order of magnitude as in ferromagnetic metals. Notably, the chiral antiferromagnetic state has a very weak and soft ferromagnetic moment of about 0.002 Bohr magnetons per Mn atom (refs 10, 12), allowing us to switch the sign of the Hall effect with a small magnetic field of around a few hundred oersted. This soft response of the large anomalous Hall effect could be useful for various applications including spintronics--for example, to develop a memory device that produces almost no perturbing stray fields.

  20. Chiral Magnetic Effect and Anomalous Hall Effect in Antiferromagnetic Insulators with Spin-Orbit Coupling.

    PubMed

    Sekine, Akihiko; Nomura, Kentaro

    2016-03-04

    We search for dynamical magnetoelectric phenomena in three-dimensional correlated systems with spin-orbit coupling. We focus on the antiferromagnetic insulator phases where the dynamical axion field is realized by the fluctuation of the antiferromagnetic order parameter. It is shown that the dynamical chiral magnetic effect, an alternating current generation by magnetic fields, emerges due to such time dependences of the order parameter as antiferromagnetic resonance. It is also shown that the anomalous Hall effect arises due to such spatial variations of the order parameter as antiferromagnetic domain walls. Our study indicates that spin excitations in antiferromagnetic insulators with spin-orbit coupling can result in nontrivial charge responses. Moreover, observing the chiral magnetic effect and anomalous Hall effect in our system is equivalent to detecting the dynamical axion field in condensed matter.

  1. Effects of visible light on the skin.

    PubMed

    Mahmoud, Bassel H; Hexsel, Camile L; Hamzavi, Iltefat H; Lim, Henry W

    2008-01-01

    Electromagnetic radiation has vast and diverse effects on human skin. Although photobiologic studies of sunlight date back to Sir Isaac Newton in 1671, most available studies focus on the UV radiation part of the spectrum. The effects of visible light and infrared radiation have not been, until recently, clearly elucidated. The goal of this review is to highlight the effects of visible light on the skin. As a result of advances in the understanding of skin optics, and comprehensive studies regarding the absorption spectrum of endogenous and exogenous skin chromophores, various biologic effects have been shown to be exerted by visible light radiation including erythema, pigmentation, thermal damage and free radical production. It has also been shown that visible light can induce indirect DNA damage through the generation of reactive oxygen species. Furthermore, a number of photodermatoses have an action spectrum in the visible light range, even though most of the currently available sunscreens offer, if any, weak protection against visible light. Conversely, because of its cutaneous biologic effects, visible light is used for the treatment of a variety of skin diseases and esthetic conditions in the form of lasers, intense pulsed light and photodynamic therapy.

  2. Separation of spin Seebeck effect and anomalous Nernst effect in Co/Cu/YIG

    NASA Astrophysics Data System (ADS)

    Tian, Dai; Li, Yufan; Qu, D.; Jin, Xiaofeng; Chien, C. L.

    2015-05-01

    The spin Seebeck effect (SSE) and Anomalous Nernst effect (ANE) have been observed in Co/Cu/YIG (yttrium iron garnet) multi-layer structure, where the ferromagnetic insulator YIG acts as the pure spin injector and the ferromagnetic metal Co layer acts as the spin current detector. With the insertion of 5 nm Cu layer, the two ferromagnetic layers are decoupled, thus allowing unambiguous separation of the SSE and ANE contributions under the same experimental conditions in the same sample.

  3. Separation of spin Seebeck effect and anomalous Nernst effect in Co/Cu/YIG

    SciTech Connect

    Tian, Dai; Li, Yufan; Qu, D.; Chien, C. L.; Jin, Xiaofeng

    2015-05-25

    The spin Seebeck effect (SSE) and Anomalous Nernst effect (ANE) have been observed in Co/Cu/YIG (yttrium iron garnet) multi-layer structure, where the ferromagnetic insulator YIG acts as the pure spin injector and the ferromagnetic metal Co layer acts as the spin current detector. With the insertion of 5 nm Cu layer, the two ferromagnetic layers are decoupled, thus allowing unambiguous separation of the SSE and ANE contributions under the same experimental conditions in the same sample.

  4. Gamma Radiation Effects on Peanut Skin Antioxidants

    PubMed Central

    de Camargo, Adriano Costa; de Souza Vieira, Thais Maria Ferreira; Regitano-D’Arce, Marisa Aparecida Bismara; Calori-Domingues, Maria Antonia; Canniatti-Brazaca, Solange Guidolin

    2012-01-01

    Peanut skin, which is removed in the peanut blanching process, is rich in bioactive compounds with antioxidant properties. The aims of this study were to measure bioactive compounds in peanut skins and evaluate the effect of gamma radiation on their antioxidant activity. Peanut skin samples were treated with 0.0, 5.0, 7.5, or 10.0 kGy gamma rays. Total phenolics, condensed tannins, total flavonoids, and antioxidant activity were evaluated. Extracts obtained from the peanut skins were added to refined-bleached-deodorized (RBD) soybean oil. The oxidative stability of the oil samples was determined using the Oil Stability Index method and compared to a control and synthetic antioxidants (100 mg/kg BHT and 200 mg/kg TBHQ). Gamma radiation changed total phenolic content, total condensed tannins, total flavonoid content, and the antioxidant activity. All extracts, gamma irradiated or not, presented increasing induction period (h), measured by the Oil Stability Index method, when compared with the control. Antioxidant activity of the peanut skins was higher than BHT. The present study confirmed that gamma radiation did not affect the peanut skin extracts’ antioxidative properties when added to soybean oil. PMID:22489142

  5. Gamma radiation effects on peanut skin antioxidants.

    PubMed

    de Camargo, Adriano Costa; de Souza Vieira, Thais Maria Ferreira; Regitano-D'Arce, Marisa Aparecida Bismara; Calori-Domingues, Maria Antonia; Canniatti-Brazaca, Solange Guidolin

    2012-01-01

    Peanut skin, which is removed in the peanut blanching process, is rich in bioactive compounds with antioxidant properties. The aims of this study were to measure bioactive compounds in peanut skins and evaluate the effect of gamma radiation on their antioxidant activity. Peanut skin samples were treated with 0.0, 5.0, 7.5, or 10.0 kGy gamma rays. Total phenolics, condensed tannins, total flavonoids, and antioxidant activity were evaluated. Extracts obtained from the peanut skins were added to refined-bleached-deodorized (RBD) soybean oil. The oxidative stability of the oil samples was determined using the Oil Stability Index method and compared to a control and synthetic antioxidants (100 mg/kg BHT and 200 mg/kg TBHQ). Gamma radiation changed total phenolic content, total condensed tannins, total flavonoid content, and the antioxidant activity. All extracts, gamma irradiated or not, presented increasing induction period (h), measured by the Oil Stability Index method, when compared with the control. Antioxidant activity of the peanut skins was higher than BHT. The present study confirmed that gamma radiation did not affect the peanut skin extracts' antioxidative properties when added to soybean oil.

  6. Anomalous and planar Righi-Leduc effects in Ni80Fe20 ferromagnets

    NASA Astrophysics Data System (ADS)

    Madon, B.; Pham, Do Ch.; Wegrowe, J.-E.; Lacour, D.; Hehn, M.; Polewczyk, V.; Anane, A.; Cros, V.

    2016-10-01

    In this paper, we report experimental evidence of anomalous and planar Righi-Leduc effects on NiFe . The Righi-Leduc effect is the thermal analog of the Hall effect, in which the electric current is replaced by the heat current and the electric field by the temperature gradient. When the material is ferromagnetic, it is well known that there are two other contributions to the Hall voltage which depend on the orientation of the magnetization. These two extra contributions are called the anomalous Hall effect when the magnetization is out of the plane of the sample and the planar Hall effect when the magnetization is in the plane of the sample. In the same way, an anomalous and a planar Righi-Leduc effects are shown to appear when a transverse temperature gradient is generated by a heat current.

  7. Quantum anomalous Hall effect in magnetically doped InAs/GaSb quantum wells.

    PubMed

    Wang, Qing-Ze; Liu, Xin; Zhang, Hai-Jun; Samarth, Nitin; Zhang, Shou-Cheng; Liu, Chao-Xing

    2014-10-03

    The quantum anomalous Hall effect has recently been observed experimentally in thin films of Cr-doped (Bi,Sb)(2)Te(3) at a low temperature (∼ 30 mK). In this work, we propose realizing the quantum anomalous Hall effect in more conventional diluted magnetic semiconductors with magnetically doped InAs/GaSb type-II quantum wells. Based on a four-band model, we find an enhancement of the Curie temperature of ferromagnetism due to band edge singularities in the inverted regime of InAs/GaSb quantum wells. Below the Curie temperature, the quantum anomalous Hall effect is confirmed by the direct calculation of Hall conductance. The parameter regime for the quantum anomalous Hall phase is identified based on the eight-band Kane model. The high sample quality and strong exchange coupling make magnetically doped InAs/GaSb quantum wells good candidates for realizing the quantum anomalous Hall insulator at a high temperature.

  8. Perpendicular magnetic anisotropy in Co2MnGa and its anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Ludbrook, B. M.; Ruck, B. J.; Granville, S.

    2017-02-01

    We report perpendicular magnetic anisotropy in the ferromagnetic Heusler alloy Co2MnGa in a MgO/Co2MnGa/Pd trilayer stack for Co2MnGa thicknesses up to 3.5 nm. There is a thickness- and temperature-dependent spin reorientation transition from perpendicular to in-plane magnetic anisotropy, which we study through the anomalous Hall effect. From the temperature dependence of the anomalous Hall effect, we observe the expected scaling of ρx y A H E with ρxx, suggesting that the intrinsic and side-jump mechanisms are largely responsible for the anomalous Hall effect in this material.

  9. Absence of anomalous Nernst effect in spin Seebeck effect of Pt/YIG

    SciTech Connect

    Miao, B. F.; Huang, S. Y.; Qu, D.; Chien, C. L.

    2016-01-15

    The Pt/YIG structure has been widely used to study spin Seebeck effect (SSE), inverse spin Hall effect, and other pure spin current phenomena. However, the magnetic proximity effect in Pt when in contact with YIG, and the potential anomalous Nernst effect (ANE) may compromise the spin current phenomena in Pt/YIG. By inserting a Cu layer of various thicknesses between Pt and YIG, we have separated the signals from the SSE and that of the ANE. It is demonstrated that the thermal voltage in Pt/YIG mainly comes from spin current due to the longitudinal SSE with negligible contribution from the ANE.

  10. Absence of anomalous Nernst effect in spin Seebeck effect of Pt/YIG

    NASA Astrophysics Data System (ADS)

    Miao, B. F.; Huang, S. Y.; Qu, D.; Chien, C. L.

    2016-01-01

    The Pt/YIG structure has been widely used to study spin Seebeck effect (SSE), inverse spin Hall effect, and other pure spin current phenomena. However, the magnetic proximity effect in Pt when in contact with YIG, and the potential anomalous Nernst effect (ANE) may compromise the spin current phenomena in Pt/YIG. By inserting a Cu layer of various thicknesses between Pt and YIG, we have separated the signals from the SSE and that of the ANE. It is demonstrated that the thermal voltage in Pt/YIG mainly comes from spin current due to the longitudinal SSE with negligible contribution from the ANE.

  11. Role of antioxidants in the skin: anti-aging effects.

    PubMed

    Masaki, Hitoshi

    2010-05-01

    Intracellular and extracellular oxidative stress initiated by reactive oxygen species (ROS) advance skin aging, which is characterized by wrinkles and atypical pigmentation. Because UV enhances ROS generation in cells, skin aging is usually discussed in relation to UV exposure. The use of antioxidants is an effective approach to prevent symptoms related to photo-induced aging of the skin. In this review, the mechanisms of ROS generation and ROS elimination in the body are summarized. The effects of ROS generated in the skin and the roles of ROS in altering the skin are also discussed. In addition, the effects of representative antioxidants on the skin are summarized with a focus on skin aging.

  12. Anomalous acoustoelectric effect in semiconductor layered structures using separated medium configuration

    NASA Astrophysics Data System (ADS)

    Abedin, M. N.; Strashilov, V. L.; Das, P.

    1990-01-01

    An anomalous acoustoelectric effect is observed in semiconductor layered structures and bulk semiconductors due to semiconductor surface conditions. We report preliminary results of this effect in semiconductors using the nondestructive surface acoustic wave (SAW) technique. The magnitude and polarity of the acoustoelectric voltages in GaAs/AlAs superlattices exhibit strong SAW frequency dependencies, a phenomenon that is not observed in bulk semiconductors. The anomalous acoustoelectric voltage (AAV) is detected in high electron mobility transistor (HEMT) and also bulk semiconductors as a function of bias voltage.

  13. Spontaneous magnetization and anomalous Hall effect in an emergent Dice lattice.

    PubMed

    Dutta, Omjyoti; Przysiężna, Anna; Zakrzewski, Jakub

    2015-06-09

    Ultracold atoms in optical lattices serve as a tool to model different physical phenomena appearing originally in condensed matter. To study magnetic phenomena one needs to engineer synthetic fields as atoms are neutral. Appropriately shaped optical potentials force atoms to mimic charged particles moving in a given field. We present the realization of artificial gauge fields for the observation of anomalous Hall effect. Two species of attractively interacting ultracold fermions are considered to be trapped in a shaken two dimensional triangular lattice. A combination of interaction induced tunneling and shaking can result in an emergent Dice lattice. In such a lattice the staggered synthetic magnetic flux appears and it can be controlled with external parameters. The obtained synthetic fields are non-Abelian. Depending on the tuning of the staggered flux we can obtain either anomalous Hall effect or its quantized version. Our results are reminiscent of Anomalous Hall conductivity in spin-orbit coupled ferromagnets.

  14. Spontaneous magnetization and anomalous Hall effect in an emergent Dice lattice

    PubMed Central

    Dutta, Omjyoti; Przysiężna, Anna; Zakrzewski, Jakub

    2015-01-01

    Ultracold atoms in optical lattices serve as a tool to model different physical phenomena appearing originally in condensed matter. To study magnetic phenomena one needs to engineer synthetic fields as atoms are neutral. Appropriately shaped optical potentials force atoms to mimic charged particles moving in a given field. We present the realization of artificial gauge fields for the observation of anomalous Hall effect. Two species of attractively interacting ultracold fermions are considered to be trapped in a shaken two dimensional triangular lattice. A combination of interaction induced tunneling and shaking can result in an emergent Dice lattice. In such a lattice the staggered synthetic magnetic flux appears and it can be controlled with external parameters. The obtained synthetic fields are non-Abelian. Depending on the tuning of the staggered flux we can obtain either anomalous Hall effect or its quantized version. Our results are reminiscent of Anomalous Hall conductivity in spin-orbit coupled ferromagnets. PMID:26057635

  15. Effect of anomalous transport coefficients on the thermal structure of the storm time auroral ionosphere

    NASA Technical Reports Server (NTRS)

    Fontheim, E. G.; Ong, R. S. B.; Roble, R. G.; Mayr, H. G.; Hoegy, W. H.; Ionson, J. A.; Baron, M. J.; Wickwar, V. B.; Vondrak, R. R.

    1978-01-01

    By analyzing an observed storm time auroral electron temperature profile it is shown that anomalous transport effects strongly influence the thermal structure of the disturbed auroral ionosphere. Such anomalous transport effects are a consequence of plasma turbulence, the existence of which has been established by a large number of observations in the auroral ionosphere. The electron and composite ion energy equations are solved with anomalous electron thermal conductivity and parallel electrical resistivity coefficients. The solutions are parameterized with respect to a phenomenological altitude-dependent anomaly coefficient A and are compared with an observed storm time electron temperature profile above Chatanika. The calculated temperature profile for the classical case (A = 1) disagrees considerably with the measured profile over most of the altitude range up to 450 km. It is shown that an anomaly coefficient with a sharp peak of the order of 10,000 centered around the F2 peak is consistent with observations.

  16. Transverse spin Seebeck effect versus anomalous and planar Nernst effects in Permalloy thin films.

    PubMed

    Schmid, M; Srichandan, S; Meier, D; Kuschel, T; Schmalhorst, J-M; Vogel, M; Reiss, G; Strunk, C; Back, C H

    2013-11-01

    Transverse magnetothermoelectric effects are studied in Permalloy thin films grown on MgO and GaAs substrates and compared to those grown on suspended SiN(x) membranes. The transverse voltage along platinum strips patterned on top of the Permalloy films is measured versus the external magnetic field as a function of the angle and temperature gradients. After the identification of the contribution of the planar and anomalous Nernst effects, we find an upper limit for the transverse spin Seebeck effect, which is several orders of magnitude smaller than previously reported.

  17. Anomalous spin precession and spin Hall effect in semiconductor quantum wells

    NASA Astrophysics Data System (ADS)

    Bi, Xintao; He, Peiru; Hankiewicz, E. M.; Winkler, R.; Vignale, Giovanni; Culcer, Dimitrie

    2013-07-01

    Spin-orbit (SO) interactions give a spin-dependent correction r̂so to the position operator, referred to as the anomalous position operator. We study the contributions of r̂so to the spin Hall effect (SHE) in quasi-two-dimensional (2D) semiconductor quantum wells with strong band-structure SO interactions that cause spin precession. The skew scattering and side-jump scattering terms in the SHE vanish, but we identify two additional terms in the SHE, due to r̂so, which have not been considered in the literature so far. One term reflects the modification of spin precession due to the action of the external electric field (the field drives the current in the quantum well), which produces, via r̂so, an effective magnetic field perpendicular to the plane of the quantum well. The other term reflects a similar modification of spin precession due to the action of the electric field created by random impurities, and appears in a careful formulation of the Born approximation. We refer to these two effects collectively as anomalous spin precession and we note that they contribute to the SHE to the first order in the SO coupling constant even though they formally appear to be of second order. In electron systems with weak momentum scattering, the contribution of the anomalous spin precession due to the external electric field equals 1/2 the usual side-jump SHE, while the additional impurity-dependent contribution depends on the form of the band-structure SO coupling. For band-structure SO coupling linear in wave vector, the two anomalous spin precession contributions cancel. For band-structure SO coupling cubic in wave vector, however, they do not cancel, and the anomalous spin precession contribution to the SHE can be detected in a high-mobility 2D electron gas with strong SO coupling. In 2D hole systems, both anomalous spin precession contributions vanish identically.

  18. Tunnelling anomalous and planar Hall effects (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Matos-Abiague, Alex; Scharf, Benedikt; Han, Jong E.; Hankiewicz, Ewelina M.; Zutic, Igor

    2016-10-01

    We theoretically show how the interplay between spin-orbit coupling (SOC) and magnetism can result in a finite tunneling Hall conductance, transverse to the applied bias. For two-dimensional tunnel junctions with a ferromagnetic lead and magnetization perpendicular to the current flow, the detected anomalous Hall voltage can be used to extract information not only about the spin polarization but also about the strength of the interfacial SOC. In contrast, a tunneling current across a ferromagnetic barrier on the surface of a three-dimensional topological insulator (TI) can induce a planar Hall response even when the magnetization is oriented along the current flow[1]. The tunneling nature of the states contributing to the planar Hall conductance can be switched from the ordinary to the Klein regimes by the electrostatic control of the barrier strength. This allows for an enhancement of the transverse response and a giant Hall angle, with the tunneling planar Hall conductance exceeding the longitudinal component. Despite the simplicity of a single ferromagnetic region, the TI/ferromagnet system exhibits a variety of functionalities. In addition to a spin-valve operation for magnetic sensing and storing information, positive, negative, and negative differential conductances can be tuned by properly adjusting the barrier potential and/or varying the magnetization direction. Such different resistive behaviors in the same system are attractive for potential applications in reconfigurable spintronic devices. [1] B. Scharf, A. Matos-Abiague, J. E. Han, E. M. Hankiewicz, and I. Zutic, arXiv:1601.01009 (2016).

  19. Exploration of Anomalous Gravity Effects by rf-Pumped Magnetized High-T(c) Superconducting Oxides

    NASA Technical Reports Server (NTRS)

    Robertson, Tony; Litchford, Ron; Peters, Randall; Thompson, Byran; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    A number of anomalous gravitational effects have been reported in the scientific literature during recent years, but there has been no independent confirmation with regard to any of these claims. Therefore, the NASA Marshall Space Flight Center, in response to the propulsion challenges specified by NASA's Breakthrough Propulsion Physics (BPP) program, proposed to explore the possibility of observing anomalous gravitation behavior through the manipulation of Josephson junction effects in magnetized high-Tc superconducting oxides. The technical goal was to critically test this revolutionary physical claim and provide a rigorous, independent, empirical confirmation (or refutation) of anomalous effects related to the manipulation of gravity by radio frequency (rf)-pumped magnetized type-2 superconductors. Because the current empirical evidence for gravity modification is anecdotal, our objective was to design, construct, and meticulously implement a discriminating experiment, which would put these observations on a more firm footing within the scientific community. Our approach is unique in that we advocate the construction of an extremely sensitive torsion balance with which to measure gravity modification effects by rf-pumped type-2 superconductor test masses. This paper reviews the anecdotal evidence for anomalous gravity effects, describes the design and development of a simplified torsion balance experiment for empirically investigating these claims, and presents the results of preliminary experiments.

  20. Effect of interstitial low level laser stimulation in skin density

    NASA Astrophysics Data System (ADS)

    Jang, Seulki; Ha, Myungjin; Lee, Sangyeob; Yu, Sungkon; Park, Jihoon; Radfar, Edalat; Hwang, Dong Hyun; Lee, Han A.; Kim, Hansung; Jung, Byungjo

    2016-03-01

    As the interest in skin was increased, number of studies on skin care also have been increased. The reduction of skin density is one of the symptoms of skin aging. It reduces elasticity of skin and becomes the reason of wrinkle formation. Low level laser therapy (LLLT) has been suggested as one of the effective therapeutic methods for skin aging as in hasten to change skin density. This study presents the effect of a minimally invasive laser needle system (MILNS) (wavelength: 660nm, power: 20mW) in skin density. Rabbits were divided into three groups. Group 1 didn't receive any laser stimulation as a control group. Group 2 and 3 as test groups were exposed to MILNS with energy of 8J and 6J on rabbits' dorsal side once a week, respectively. Skin density of rabbits was measured every 12 hours by using an ultrasound skin scanner.

  1. The anomalous effect of surface diffusion on the nuclear magnetic resonance signal in restricted geometry.

    PubMed

    Edirisinghe, E P N S; Apalkov, V M; Cymbalyuk, G S

    2010-04-14

    Anisotropy of diffusion properties in a specimen plays a key role in numerous applications of nuclear magnetic resonance (NMR) imaging, like non-invasive tracking of fibers in the central nervous system. We suggest that contrasting fiber structures with certain diameters could be improved if second-order effects are taken into account. We introduce a procedure consisting of two standard diffusion NMR experiments differing in their gradient pulse characteristics. These two echo signals will be called the background and principal signals. We show that the difference obtained by subtracting one echo signal from the other has either typical or anomalous properties. In the typical case, as the duration of the gradient pulse in the second experiment is set to smaller and smaller values, the difference from the background echo signal tends toward its maximum. In contrast, in the anomalous case the difference between the background and the principal signals has a maximum at a certain nonzero duration of the pulse in the second experiment. This critical duration is determined by different characteristics, including the diameters of fibers. For this anomalous effect to take place the fast surface diffusion channel coupled to the surrounding media is required. The diffusion of magnetic molecules along the surface of restricted media and the coupling of the surface and the bulk translational motions can strongly modify the echo attenuation NMR signal. The origin of this strong anomalous effect is the change of the symmetry of the lowest diffusion eigenmode of the system. We illustrate the effect of surface diffusion for a cylindrically symmetric system and describe the experimental conditions under which the anomalous behavior of the echo signals can be observed.

  2. Temperature, pressure, and compositional effects on anomalous or "self" preservation of gas hydrates

    USGS Publications Warehouse

    Stern, L.A.; Circone, S.; Kirby, S.H.; Durham, W.B.

    2003-01-01

    We previously reported on a thermal regime where pure, polycrystalline methane hydrate is preserved metastably in bulk at up to 75 K above its nominal temperature stability limit of 193 K at 0.1 MPa, following rapid release of the sample pore pressure. Large fractions (>50 vol.%) of methane hydrate can be preserved for 2-3 weeks by this method, reflecting the greatly suppressed rates of dissociation that characterize this "anomalous preservation" regime. This behavior contrasts that exhibited by methane hydrate at both colder (193-240 K) and warmer (272-290 K) isothermal test conditions, where dissociation rates increase monotonically with increasing temperature. Here, we report on recent experiments that further investigate the effects of temperature, pressure, and composition on anomalous preservation behavior. All tests conducted on sI methane hydrate yielded self-consistent results that confirm the highly temperature-sensitive but reproducible nature of anomalous preservation behavior. Temperature-stepping experiments conducted between 250 and 268 K corroborate the relative rates measured previously in isothermal preservation tests, and elevated pore-pressure tests showed that, as expected, dissociation rates are further reduced with increasing pressure. Surprisingly, sII methane-ethane hydrate was found to exhibit no comparable preservation effect when rapidly depressurized at 268 K, even though it is thermodynamically stable at higher temperatures and lower pressures than sI methane hydrate. These results, coupled with SEM imaging of quenched sample material from a variety of dissociation tests, strongly support our earlier arguments that ice-"shielding" effects provided by partial dissociation along hydrate grain surfaces do not serve as the primary mechanism for anomalous preservation. The underlying physical-chemistry mechanism(s) of anomalous preservation remains elusive, but appears to be based more on textural or morphological changes within the hydrate

  3. Extraordinary Hall effect in Kondo-type systems: Contributions from anomalous velocity

    NASA Astrophysics Data System (ADS)

    Levy, P. M.

    1988-10-01

    Kondo systems exhibit a relatively large extraordinary Hall effect which is due to asymmetric resonant scattering of conduction electrons. Theories based on the skew scattering mechanism account for data at high temperatures T>TK (the Kondo temperature) but are unable to explain the very-low-temperature variation of the Hall constant observed in heavy-fermion compounds. Aside from the ordinary Hall effect, caused by the Lorentz force and skew scattering (which makes the scattering probability antisymmetric with respect to interchange of scattering vectors), there exists an additional contribution to the Hall effect known as the anomalous-velocity contribution. This contribution is due to a change in the expression for the current operator in the presence of spin-orbit forces. We derive an expression for the anomalous velocity in terms of the T matrices describing conduction-electron scattering; it is not limited to weak spin-orbit scattering as were previous results. We use the Anderson model of local moments in metals to write this scattering in terms of the mixing interaction between local and conduction electrons, and the local state's Green's function. The transverse Hall current due to anomalous velocity is determined and evaluated in two limits. At high temperature, we use the weak-coupling form of the local state's Green's function; at T=0 K a phase-shift analysis is used, and we rely on the Friedel-Langreth sum rule to give us the phase shift at the Fermi surface. At high temperatures we find that the contribution from anomalous velocity to the Hall constant is quite small compared to that from skew scattering. On the contrary, at low temperatures the anomalous velocity makes the dominant contribution to the Hall constant in Kondo systems.

  4. Effects of thermal water on skin regeneration.

    PubMed

    Faga, Angela; Nicoletti, Giovanni; Gregotti, Cesarina; Finotti, Valentina; Nitto, Agnese; Gioglio, Luciana

    2012-05-01

    An experimental study was carried out in an animal (New Zealand white rabbit) wound model to evaluate any effects of a hypotonic, bicarbonate-calcium-magnesium mineral water (Comano thermal water) on skin regeneration, comparing the healing rate of split-thickness skin graft donor sites treated with the thermal water wet dressing versus a standard petrolatum gauze dressing versus a saline solution wet dressing. The study was performed in two steps; an overall of 22 animals were enrolled in the study. The wound healing progress was evaluated both by the surgeons and by the histologists. Sixty-four punch biopsies were examined in all. The histological samples were examined after staining with haematoxylin and eosin, Masson's and orcein staining and under a transmission electron microscope. The data were statistically analysed. The Comano thermal water proved to improve skin regeneration, not only by increasing keratinocyte proliferation and migration but also favourably modulating the regenerated collagen and elastic fibres in the dermis. We propose that the results of the topical treatment with the thermal water could be due to the favourable combination of a local wet environment with an anti-inflammatory action and that the regenerative properties of Comano thermal water observed in rabbits could also be applied for human use.

  5. Prospect of quantum anomalous Hall and quantum spin Hall effect in doped kagome lattice Mott insulators

    PubMed Central

    Guterding, Daniel; Jeschke, Harald O.; Valentí, Roser

    2016-01-01

    Electronic states with non-trivial topology host a number of novel phenomena with potential for revolutionizing information technology. The quantum anomalous Hall effect provides spin-polarized dissipation-free transport of electrons, while the quantum spin Hall effect in combination with superconductivity has been proposed as the basis for realizing decoherence-free quantum computing. We introduce a new strategy for realizing these effects, namely by hole and electron doping kagome lattice Mott insulators through, for instance, chemical substitution. As an example, we apply this new approach to the natural mineral herbertsmithite. We prove the feasibility of the proposed modifications by performing ab-initio density functional theory calculations and demonstrate the occurrence of the predicted effects using realistic models. Our results herald a new family of quantum anomalous Hall and quantum spin Hall insulators at affordable energy/temperature scales based on kagome lattices of transition metal ions. PMID:27185665

  6. Prospect of quantum anomalous Hall and quantum spin Hall effect in doped kagome lattice Mott insulators

    NASA Astrophysics Data System (ADS)

    Guterding, Daniel; Jeschke, Harald O.; Valentí, Roser

    2016-05-01

    Electronic states with non-trivial topology host a number of novel phenomena with potential for revolutionizing information technology. The quantum anomalous Hall effect provides spin-polarized dissipation-free transport of electrons, while the quantum spin Hall effect in combination with superconductivity has been proposed as the basis for realizing decoherence-free quantum computing. We introduce a new strategy for realizing these effects, namely by hole and electron doping kagome lattice Mott insulators through, for instance, chemical substitution. As an example, we apply this new approach to the natural mineral herbertsmithite. We prove the feasibility of the proposed modifications by performing ab-initio density functional theory calculations and demonstrate the occurrence of the predicted effects using realistic models. Our results herald a new family of quantum anomalous Hall and quantum spin Hall insulators at affordable energy/temperature scales based on kagome lattices of transition metal ions.

  7. Quantum anomalous Hall effect and tunable topological states in 3d transition metals doped silicene.

    PubMed

    Zhang, Xiao-Long; Liu, Lan-Feng; Liu, Wu-Ming

    2013-10-09

    Silicene is an intriguing 2D topological material which is closely analogous to graphene but with stronger spin orbit coupling effect and natural compatibility with current silicon-based electronics industry. Here we demonstrate that silicene decorated with certain 3d transition metals (Vanadium) can sustain a stable quantum anomalous Hall effect using both analytical model and first-principles Wannier interpolation. We also predict the quantum valley Hall effect and electrically tunable topological states could be realized in certain transition metal doped silicene where the energy band inversion occurs. Our findings provide new scheme for the realization of quantum anomalous Hall effect and platform for electrically controllable topological states which are highly desirable for future nanoelectronics and spintronics application.

  8. Prospect of quantum anomalous Hall and quantum spin Hall effect in doped kagome lattice Mott insulators.

    PubMed

    Guterding, Daniel; Jeschke, Harald O; Valentí, Roser

    2016-05-17

    Electronic states with non-trivial topology host a number of novel phenomena with potential for revolutionizing information technology. The quantum anomalous Hall effect provides spin-polarized dissipation-free transport of electrons, while the quantum spin Hall effect in combination with superconductivity has been proposed as the basis for realizing decoherence-free quantum computing. We introduce a new strategy for realizing these effects, namely by hole and electron doping kagome lattice Mott insulators through, for instance, chemical substitution. As an example, we apply this new approach to the natural mineral herbertsmithite. We prove the feasibility of the proposed modifications by performing ab-initio density functional theory calculations and demonstrate the occurrence of the predicted effects using realistic models. Our results herald a new family of quantum anomalous Hall and quantum spin Hall insulators at affordable energy/temperature scales based on kagome lattices of transition metal ions.

  9. Crossover to the anomalous quantum regime in the extrinsic spin Hall effect of graphene

    NASA Astrophysics Data System (ADS)

    Milletarı, Mirco; Ferreira, Aires

    2016-11-01

    Recent reports of spin-orbit coupling enhancement in chemically modified graphene have opened doors to studies of the spin Hall effect with massless chiral fermions. Here, we theoretically investigate the interaction and impurity density dependence of the extrinsic spin Hall effect in spin-orbit coupled graphene. We present a nonperturbative quantum diagrammatic calculation of the spin Hall response function in the strong-coupling regime that incorporates skew scattering and anomalous impurity density-independent contributions on equal footing. The spin Hall conductivity dependence on Fermi energy and electron-impurity interaction strength reveals the existence of experimentally accessible regions where anomalous quantum processes dominate. Our findings suggest that spin-orbit-coupled graphene is an ideal model system for probing the competition between semiclassical and bona fide quantum scattering mechanisms underlying the spin Hall effect.

  10. Skin and bulk temperature difference at Lake Tahoe: A case study on lake skin effect

    NASA Astrophysics Data System (ADS)

    Wilson, R. Chris; Hook, Simon J.; Schneider, Philipp; Schladow, S. Geoffrey

    2013-09-01

    water, infrared radiometers on satellites measure radiation leaving from the surface skin layer and therefore the retrieved temperature is representative of the skin layer. This is slightly different from the bulk layer deeper in the water where various floating thermometers take temperature measurements to validate satellite measurements. The difference between the bulk and skin temperature (skin effect) must be understood to properly validate schemes that use surface skin temperature to infer bulk temperatures. Further skin temperatures retrieved over inland waters may show different patterns to those retrieved over oceans due to differences in conditions such as wind speed, aerosols, and elevation. We have analyzed the differences between the skin and bulk temperatures at four permanent monitoring stations (buoys) located on Lake Tahoe since 1999 and compared the results with similar studies over the ocean typically obtained from boat cruises. Skin effect distributions were found to be consistent across the buoys; however, the diurnal behavior of the skin effect was slightly different and shown to be related to wind speed measured at an individual buoy. When wind speed was less than 2 m s-1, the skin temperature osclillated and greatly increased the uncertainty in the skin effect reported over Lake Tahoe. When downwelling sky radiation was increased from clouds or high humidity, this led to nighttime skin temperatures that were warmer than bulk temperatures by as much as 0.5 K. The size of the warm skin effect is larger than other ocean studies that observed warm nighttime skin values around 0.1 K. The nighttime skin effect was seen to be more consistent with a smaller standard deviation compared to the daytime skin effect. The nighttime skin behavior had a mean and standard deviation that ranged between 0.3 and 0.5 K and between 0.3 and 0.4 K, respectively. In contrast, daytime skin effect was strongly influenced by direct solar illumination and typically had a

  11. Sun’s effect on skin

    MedlinePlus Videos and Cool Tools

    The skin uses sunlight to help manufacture vitamin D, which is important for normal bone formation. But sometimes its ultraviolet light can be ... to age prematurely. Suntanning occurs because exposure to sunlight causes the skin to produce more melanin and ...

  12. Skin Exposures & Effects in the Workplace

    MedlinePlus

    ... through the corneocytes. Figure 3: Through the appendages (hair follicles, glands) As shown in Figure 3, the third ... through the skin is skin appendages (i.e., hair follicles and glands). This pathway is usually insignificant because ...

  13. Anomalously large isotope effect in the glass transition of water

    SciTech Connect

    Gainaru, Catalin; Agapov, Alexander L.; Fuentes-Landete, Violeta; Amann-Winkel, Katrin; Nelson, Helge; Köster, Karsten W.; Kolesnikov, Alexander I.; Novikov, Vladimir N.; Richert, Ranko; Böhmer, Roland; Loerting, Thomas; Sokolov, Alexei P.

    2014-11-24

    Here we present the discovery of an unusually large isotope effect in the structural relaxation and the glass transition temperature Tg of water. Dielectric relaxation spectroscopy of low-density as well as of vapor deposited amorphous water reveal Tg differences of 10±2K between H2O and D2O, sharply contrasting with other hydrogen bonded liquids for which H/D exchange increases Tg by typically less than 1K. We show that the large isotope effect and the unusual variation of relaxation times in water at low temperatures can be explained in terms of quantum effects. Thus, our findings shed new light on water's peculiar low-temperature dynamics and the possible role of quantum effects in its structural relaxation, and possibly in dynamics of other low molecular weight liquids.

  14. Anomalously large isotope effect in the glass transition of water

    DOE PAGES

    Gainaru, Catalin; Agapov, Alexander L.; Fuentes-Landete, Violeta; ...

    2014-11-24

    Here we present the discovery of an unusually large isotope effect in the structural relaxation and the glass transition temperature Tg of water. Dielectric relaxation spectroscopy of low-density as well as of vapor deposited amorphous water reveal Tg differences of 10±2K between H2O and D2O, sharply contrasting with other hydrogen bonded liquids for which H/D exchange increases Tg by typically less than 1K. We show that the large isotope effect and the unusual variation of relaxation times in water at low temperatures can be explained in terms of quantum effects. Thus, our findings shed new light on water's peculiar low-temperaturemore » dynamics and the possible role of quantum effects in its structural relaxation, and possibly in dynamics of other low molecular weight liquids.« less

  15. Understanding Engineered Nanomaterial Skin Interactions and the Modulatory Effects of UVR Skin Exposure

    PubMed Central

    Jatana, Samreen; DeLouise, Lisa A.

    2013-01-01

    The study of engineered nanomaterials for the development of technological applications, nanomedicine, and nano-enabled consumer products is an ever expanding discipline as is the concern over the impact of nanotechnology on human environmental health and safety. In this review we discuss the current state of understanding of nanomaterial skin interactions with a specific emphasis on the effects of ultra-violet radiation (UVR) skin exposure. Skin is the largest organ of the body and is typically exposed to UVR on a daily basis. This necessitates the need to understand how UVR skin exposure can influence nanomaterial skin penetration, alter nanomaterial systemic trafficking, toxicity, and skin immune function. We explore the unique dichotomy that UVR has in inducing both deleterious and therapeutic effects on skin. The subject matter covered in this review is broadly informative and will raise awareness of potential increased risks from nanomaterial skin exposure associated with specific occupational and life style choices. The UVR induced immunosuppressive response in skin raises intriguing questions that motivate future research directions in the nanotoxicology and nanomedicine fields. PMID:24123977

  16. Adverse and beneficial effects of plant extracts on skin and skin disorders.

    PubMed

    Mantle, D; Gok, M A; Lennard, T W

    2001-06-01

    Plants are of relevance to dermatology for both their adverse and beneficial effects on skin and skin disorders respectively. Virtually all cultures worldwide have relied historically, or continue to rely on medicinal plants for primary health care. Approximately one-third of all traditional medicines are for treatment of wounds or skin disorders, compared to only 1-3% of modern drugs. The use of such medicinal plant extracts for the treatment of skin disorders arguably has been based largely on historical/anecdotal evidence, since there has been relatively little data available in the scientific literature, particularly with regard to the efficacy of plant extracts in controlled clinical trials. In this article therefore, adverse and beneficial aspects of medicinal plants relating to skin and skin disorders have been reviewed, based on recently available information from the peer-reviewed scientific literature. Beneficial aspects of medicinal plants on skin include: healing of wounds and burn injuries (especially Aloe vera); antifungal, antiviral, antibacterial and acaricidal activity against skin infections such as acne, herpes and scabies (especially tea tree (Melaleuca alternifolia) oil); activity against inflammatory/immune disorders affecting skin (e.g. psoriasis); and anti-tumour promoting activity against skin cancer (identified using chemically-induced two-stage carcinogenesis in mice). Adverse effects of plants on skin reviewed include: irritant contact dermatitis caused mechanically (spines, irritant hairs) or by irritant chemicals in plant sap (especially members of the Ranunculaceae, Euphorbiaceae and Compositae plant families); phytophotodermatitis resulting from skin contamination by plants containing furocoumarins, and subsequent exposure to UV light (notably members of the Umbelliferae and Rutaceae plant families); and immediate (type I) or delayed hypersensitivity contact reactions mediated by the immune system in individuals sensitized to plants

  17. Evidence for Anomalous Effects on the Current Evolution in Tokamak Operating Scenarios

    SciTech Connect

    Casper, T; Jayakumar, R; Allen, S; Holcomb, C; Makowski, M; Pearlstein, L; Berk, H; Greenfield, C; Luce, T; Petty, C; Politzer, P; Wade, M; Murakami, M; Kessel, C

    2006-10-03

    Alternatives to the usual picture of advanced tokamak (AT) discharges are those that form when anomalous effects alter the plasma current and pressure profiles and those that achieve stationary characteristics through mechanisms so that a measure of desired AT features is maintained without external current-profile control. Regimes exhibiting these characteristics are those where the safety factor (q) evolves to a stationary profile with the on-axis and minimum q {approx} 1 and those with a deeply hollow current channel and high values of q. Operating scenarios with high fusion performance at low current and where the inductively driven current density achieves a stationary configuration with either small or non-existing sawteeth may enhance the neutron fluence per pulse on ITER and future burning plasmas. Hollow current profile discharges exhibit high confinement and a strong ''box-like'' internal transport barrier (ITB). We present results providing evidence for current profile formation and evolution exhibiting features consistent with anomalous effects or with self-organizing mechanisms. Determination of the underlying physical processes leading to these anomalous effects is important for scaling of current experiments for application in future burning plasmas.

  18. Revisiting the Anomalous rf Field Penetration into a Warm Plasma

    SciTech Connect

    Igor D. Kaganovich; Oleg V. Polomarov; Constantine E. Theodosiou

    2005-06-24

    Radio-frequency [rf] waves do not penetrate into a plasma and are damped within it. The electric field of the wave and plasma current are concentrated near the plasma boundary in a skin layer. Electrons can transport the plasma current away from the skin layer due to their thermal motion. As a result, the width of the skin layer increases when electron temperature effects are taken into account. This phenomenon is called anomalous skin effect. The anomalous penetration of the rf electric field occurs not only for transversely propagating to the plasma boundary wave (inductively coupled plasmas) but also for the wave propagating along the plasma boundary (capacitively coupled plasmas). Such anomalous penetration of the rf field modifies the structure of the capacitive sheath. Recent advances in the nonlinear, non-local theory of the capacitive sheath are reported. It is shown that separating the electric field profile into exponential and non-exponential parts yields an efficient qualitative and quantitative description of the anomalous skin effect in both inductively and capacitively coupled plasma.

  19. Effects of sunscreen on skin cancer and photoaging.

    PubMed

    Iannacone, Michelle R; Hughes, Maria Celia B; Green, Adèle C

    2014-01-01

    Application of sunscreen to the skin is widely used as an adjunct strategy, along with wearing protective clothing and seeking shade, to protect against skin cancer and photoaging that result from excessive sun exposure. Many epidemiological studies of case-control and cohort study design have studied the effects of sunscreen use on skin cancer, and more recently photoaging, but their findings have been mostly uninformative. This review of results of randomized controlled trials shows that the evidence, though limited, supports beneficial effects of sunscreen application on the occurrence of skin cancers and skin photoaging.

  20. Effect of Skin-To-Skin Contact on Preterm Infant Skin Barrier Function and Hospital-Acquired Infection

    PubMed Central

    Abouelfettoh, Amel; Ludington-Hoe, Susan M.; Burant, Chris J.; Visscher, Marty O.

    2011-01-01

    Background The preterm infants' skin is structurally and functionally immature at birth because of immature stratum corneum barrier function, leading to problems with fluid loses, thermoregulation, and infection. Two parameters of barrier function can be non-invasively assessed: Stratum Corneum Hydration (SCH) and Transepidermal Water Loss (TEWL). Skin-to-Skin Care (SSC) is the proposed independent variable that might affect barrier function by decreasing TEWL and increasing SCH, thereby improving stratum corneum barrier function and consequently decreasing the rate of infection. No study of SSC's effects on TEWL and SCH of preterm infants could be found. The purpose of the study was to determine the effect of 5 daily Skin-to-Skin Contact sessions on infant skin hydration (SCH), transepidermal evaporated water loss (TEWL), and on SCH when TEWL was controlled, and on the presence of hospital acquired infection. Methods A one-group pretest-test-posttest design with 10 preterm infants (28 - 30 wks GA < 32 wks postmenstrual age, and no infection at entry). Test = 90 minutes of SSC; pre-test and post-test = 30 minutes each of prone positioning in an incubator. SCH and TEWL were taken on Days 1 and 5 at the beginning, middle and end of each period using Multi-Probe Adaptor. A 3 X 3 X 2 Repeated Measures Mixed Models Design, including a covariate, was used to analyze level of Skin Hydration. Specifically, the model tested comparisons in SCH made across repetitions, time, and days, as well as all possible interactions while controlling for TEWL. Descriptive statistics described the number of positive blood cultures during hospitalization and the presence of infections four weeks post-discharge. Results Significant differences in skin hydration were found across TIME (Pre-SSC, SSC, Post-SSC) (F = 21.86; p < 0.001). One infant had a positive blood culture during hospitalization; no infants had signs of infection by 4 weeks post-discharge. Conclusions The study has begun

  1. Effect of thermodynamic activity on skin permeation and skin concentration of triamcinolone acetonide.

    PubMed

    Ishii, Hiroshi; Todo, Hiroaki; Sugibayashi, Kenji

    2010-04-01

    Effects of thermodynamic activity and the state (solution/suspension) of triamcinolone acetonide (TA) on skin permeation and concentration were physicochemically and kinetically analyzed. Permeation of TA through a silicone membrane, hairless rat skin (full-thickness skin or stripped skin) or a three-dimensional cultured human skin model (LSE-high) was determined and a permeability coefficient (P), partition coefficient (K) , diffusion coefficient (D) and steady-state flux (J) were calculated. The resulting J values proportionally increased with an increase in the TA activity in the drug solution and similar P, K and D values were obtained independent of the TA state (solution/suspension) in all membranes except for full-thickness hairless rat skin. On the other hand, the TA permeation through full-thickness hairless rat skin with the 1000 microg/ml suspension was higher than that expected judging by the thermodynamic acidity of TA. Higher D and P values were also obtained in the skin permeation of TA from the 1000 microg/ml suspension. Morphological observation of the skin surface by scanning electron microscope (SEM) showed the presence of TA solids in the hair follicles after application of the TA suspension. These results suggest that dissolved TA may be permeated predominantly through the stratum corneum, but that solid TA may be passed through the hair follicles to enter the dermis. The present physicochemical and kinetic analysis provides useful information to develop topical steroid formulations.

  2. Enhancement of perpendicular magnetic anisotropy and anomalous hall effect in Co/Ni multilayers

    NASA Astrophysics Data System (ADS)

    Liu, Yiwei; Zhang, Jingyan; Jiang, Shaolong; Liu, Qianqian; Li, Xujing; Yu, Guanghua

    2016-12-01

    The perpendicular magnetic anisotropy (PMA) and the anomalous Hall effect (AHE) in Co/Ni multilayer were optimized by manipulating its interface structure (inducing HfO2 capping layer and Pt insertion) and post-annealing treatment. A strong PMA can be obtained in Co/Ni multilayers with HfO2 capping layer even after annealing at 400 °C. The heavy metal Hf may improve the interfacial spin-orbit coupling, which responsible for the enhanced PMA and high annealing stability. Moreover, the multilayer containing HfO2 capping layer also exhibited high saturation anomalous Hall resistivity through post-annealing, which is 0.85 μΩ cm after annealing at 375 °C, 211% larger than in the sample at deposited state which is only 0.27 μΩ cm. The enhancement of AHE is mainly attributed to the interface scattering through post-annealing treatment.

  3. [Effect of an anomalous broadening of the synchronization band after electric stimulation of heart tissues].

    PubMed

    Mazurov, M E

    1987-01-01

    Synchronization effects of the second order induced by a change of the action potential (AP) shape in relation to the frequency of periodic stimulation were studied. Mechanism of anomalous increase of the synchronization band at periodic stimulation of the heart fibers was explained. By means of a modified method of synchronization diagrams the synchronization bands were calculated for possible stimulation regimes taking into account a change in RP shape and dynamic threshold (DT) depending on the frequency of the initiated regimes. Regions of stimulating signals parameters (multiplicity regions or prolonging regions) were discovered, within the range of which the same stimulating signal may induce different synchronization regimes. Physiological meaning of the existence of anomalous synchronization regimes which significantly broaden the adaptation possibilities of the heart is discussed.

  4. Prediction of near-room-temperature quantum anomalous Hall effect on honeycomb materials.

    PubMed

    Wu, Shu-Chun; Shan, Guangcun; Yan, Binghai

    2014-12-19

    Recently, the long-sough quantum anomalous Hall effect was realized in a magnetic topological insulator. However, the requirement of an extremely low temperature (approximately 30 mK) hinders realistic applications. Based on ab initio band structure calculations, we propose a quantum anomalous Hall platform with a large energy gap of 0.34 and 0.06 eV on honeycomb lattices comprised of Sn and Ge, respectively. The ferromagnetic (FM) order forms in one sublattice of the honeycomb structure by controlling the surface functionalization rather than dilute magnetic doping, which is expected to be visualized by spin polarized STM in experiment. Strong coupling between the inherent quantum spin Hall state and ferromagnetism results in considerable exchange splitting and, consequently, an FM insulator with a large energy gap. The estimated mean-field Curie temperature is 243 and 509 K for Sn and Ge lattices, respectively. The large energy gap and high Curie temperature indicate the feasibility of the quantum anomalous Hall effect in the near-room-temperature and even room-temperature regions.

  5. Skin-lightening cosmetics: frequent, potentially severe adverse effects.

    PubMed

    2011-09-01

    Skin-lightening cosmetics are used by many women and men around the world. The products contain a variety of substances, which are often unknown to the users. Most of these products include topical corticosteroids, hydroquinone and mercury salts. Many other substances may be added. Several surveys and cohort studies, including several thousand individuals, have shown that regular application of skin-lightening cosmetics to large surface areas can have irreversible cutaneous adverse effects, such as patchy hyper- or hypopigmentation, skin atrophy, stretch marks and delayed wound healing, and can also mask or, on the contrary, promote or reactivate skin infections. Cases of skin cancer have been attributed to skin-lightening cosmetics. A Senegalese cohort study of 147 women showed a statistically significant increase in the risk of hypertension and diabetes linked to the use of skin-lightening agents. Other systemic adverse effects attributed to skin-lightening cosmetics include Cushing's syndrome, adrenal insufficiency, nephrotic syndrome, neurological disorders, and ocular disorders. Hypersensitivity reactions, including anaphylaxis, have also been attributed to these products. Many skin-lightening cosmetics contain substances that can harm the unborn child. For example, tretinoin is teratogenic while salicylic acid is feto-toxic. In practice, users are often unaware of the risk of severe adverse effects associated with skin-lightening cosmetics. Users should be informed of these adverse effects and encouraged to stop using these products, especially when skin disorders appear.

  6. Large anomalous Hall effect driven by a nonvanishing Berry curvature in the noncolinear antiferromagnet Mn3Ge.

    PubMed

    Nayak, Ajaya K; Fischer, Julia Erika; Sun, Yan; Yan, Binghai; Karel, Julie; Komarek, Alexander C; Shekhar, Chandra; Kumar, Nitesh; Schnelle, Walter; Kübler, Jürgen; Felser, Claudia; Parkin, Stuart S P

    2016-04-01

    It is well established that the anomalous Hall effect displayed by a ferromagnet scales with its magnetization. Therefore, an antiferromagnet that has no net magnetization should exhibit no anomalous Hall effect. We show that the noncolinear triangular antiferromagnet Mn3Ge exhibits a large anomalous Hall effect comparable to that of ferromagnetic metals; the magnitude of the anomalous conductivity is ~500 (ohm·cm)(-1) at 2 K and ~50 (ohm·cm)(-1) at room temperature. The angular dependence of the anomalous Hall effect measurements confirms that the small residual in-plane magnetic moment has no role in the observed effect except to control the chirality of the spin triangular structure. Our theoretical calculations demonstrate that the large anomalous Hall effect in Mn3Ge originates from a nonvanishing Berry curvature that arises from the chiral spin structure, and that also results in a large spin Hall effect of 1100 (ħ/e) (ohm·cm)(-1), comparable to that of platinum. The present results pave the way toward the realization of room temperature antiferromagnetic spintronics and spin Hall effect-based data storage devices.

  7. Anomalous-circular photogalvanic effect in a GaAs/AlGaAs two-dimensional electron gas

    NASA Astrophysics Data System (ADS)

    Tang, C. G.; Chen, Y. H.; Liu, Y.; Wang, Z. G.

    2009-09-01

    We have studied the circular photogalvanic effect (CPGE) in a GaAs/AlGaAs two-dimensional electron gas excited by near infrared light at room temperature. The anomalous CPGE observed under normal incidence indicates a swirling current which is realized by a radial spin current via the reciprocal spin-Hall effect. The anomalous CPGE exhibits a cubic cosine dependence on the incidence angle, which is discussed in line with the above interpretation.

  8. Anomalous-circular photogalvanic effect in a GaAs/AlGaAs two-dimensional electron gas.

    PubMed

    Tang, C G; Chen, Y H; Liu, Y; Wang, Z G

    2009-09-16

    We have studied the circular photogalvanic effect (CPGE) in a GaAs/AlGaAs two-dimensional electron gas excited by near infrared light at room temperature. The anomalous CPGE observed under normal incidence indicates a swirling current which is realized by a radial spin current via the reciprocal spin-Hall effect. The anomalous CPGE exhibits a cubic cosine dependence on the incidence angle, which is discussed in line with the above interpretation.

  9. Large anomalous Hall effect driven by a nonvanishing Berry curvature in the noncolinear antiferromagnet Mn3Ge

    PubMed Central

    Nayak, Ajaya K.; Fischer, Julia Erika; Sun, Yan; Yan, Binghai; Karel, Julie; Komarek, Alexander C.; Shekhar, Chandra; Kumar, Nitesh; Schnelle, Walter; Kübler, Jürgen; Felser, Claudia; Parkin, Stuart S. P.

    2016-01-01

    It is well established that the anomalous Hall effect displayed by a ferromagnet scales with its magnetization. Therefore, an antiferromagnet that has no net magnetization should exhibit no anomalous Hall effect. We show that the noncolinear triangular antiferromagnet Mn3Ge exhibits a large anomalous Hall effect comparable to that of ferromagnetic metals; the magnitude of the anomalous conductivity is ~500 (ohm·cm)−1 at 2 K and ~50 (ohm·cm)−1 at room temperature. The angular dependence of the anomalous Hall effect measurements confirms that the small residual in-plane magnetic moment has no role in the observed effect except to control the chirality of the spin triangular structure. Our theoretical calculations demonstrate that the large anomalous Hall effect in Mn3Ge originates from a nonvanishing Berry curvature that arises from the chiral spin structure, and that also results in a large spin Hall effect of 1100 (ħ/e) (ohm·cm)−1, comparable to that of platinum. The present results pave the way toward the realization of room temperature antiferromagnetic spintronics and spin Hall effect–based data storage devices. PMID:27152355

  10. Effects of air pollution on the skin: A review.

    PubMed

    Puri, Poonam; Nandar, Shashi Kumar; Kathuria, Sushruta; Ramesh, V

    2017-02-07

    The increase in air pollution over the years has had major effects on the human skin. Various air pollutants such as ultraviolet radiation, polycyclic aromatic hydrocarbons, volatile organic compounds, oxides, particulate matter, ozone and cigarette smoke affect the skin as it is the outermost barrier. Air pollutants damage the skin by inducing oxidative stress. Although human skin acts as a biological shield against pro-oxidative chemicals and physical air pollutants, prolonged or repetitive exposure to high levels of these pollutants may have profound negative effects on the skin. Exposure to ultraviolet radiation has been associated with extrinsic skin aging and skin cancers. Cigarette smoke contributes to premature aging and an increase in the incidence of psoriasis, acne and skin cancers. It is also implicated in allergic skin conditions such as atopic dermatitis and eczema. Polyaromatic hydrocarbons are associated with extrinsic skin aging, pigmentation, cancers and acneiform eruptions. Volatile organic compounds have been associated with atopic dermatitis. Given the increasing levels of air pollution and its detrimental effects on the skin, it is advisable to use strategies to decrease air pollution.

  11. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: An Extended Extrinsic Mechanism for Anomalous Hall Effect

    NASA Astrophysics Data System (ADS)

    Yan, Yu-Zhen; Li, Hui-Wu; Hu, Liang-Bin

    2009-12-01

    The extrinsic mechanism for anomalous Hall effect in ferromagnets is extended to include the contributions both from spin-orbit-dependent impurity scattering and from the spin-orbit coupling induced by external electric fields. The results obtained suggest that, within the framework of the extrinsic mechanisms, the anomalous Hall current in a ferromagnet may also contain a substantial amount of dissipationless contribution independent of impurity scattering. After the contribution from the spin-orbit coupling induced by external electric fields is included, the total anomalous Hall conductivity is about two times larger than that due to spin-orbit dependent impurity scatterings.

  12. Disorder Effect on Chiral Edge Modes and Anomalous Hall Conductance in Weyl Semimetals

    NASA Astrophysics Data System (ADS)

    Takane, Yositake

    2016-12-01

    Typical Weyl semimetals host chiral surface states and hence show an anomalous Hall response. Although a Weyl semimetal phase is known to be robust against weak disorder, the effect of disorder on chiral states has not been fully clarified so far. We study the behavior of such chiral states in the presence of disorder and its consequences on an anomalous Hall response, focusing on a thin slab of Weyl semimetal with chiral surface states along its edge. It is shown that weak disorder does not disrupt chiral edge states but crucially affects them owing to the renormalization of a mass parameter: the number of chiral edge states changes depending on the strength of disorder. It is also shown that the Hall conductance is quantized when the Fermi level is located near Weyl nodes within a finite-size gap. This quantization of the Hall conductance collapses once the strength of disorder exceeds a critical value, suggesting that it serves as a probe to distinguish a Weyl semimetal phase from a diffusive anomalous Hall metal phase.

  13. Anomalous coupling, top-mass and parton-shower effects in W + W - production

    NASA Astrophysics Data System (ADS)

    Bellm, J.; Gieseke, S.; Greiner, N.; Heinrich, G.; Plätzer, S.; Reuschle, C.; von Soden-Fraunhofen, J. F.

    2016-05-01

    We calculate the process ppto {W}+{W}-to {e}+{ν}_e{μ}-{overline{ν}}_{μ } at NLO QCD, including also effective field theory (EFT) operators mediating the ggW + W - interaction, which first occur at dimension eight. We further combine the NLO and EFT matrix elements produced by G oS am with the H erwig7/M atchbox framework, which offers the possibility to study the impact of a parton shower. We assess the effects of the anomalous couplings by comparing them to top-mass effects as well as uncertainties related to variations of the renormalisation, factorisation and hard shower scales.

  14. Nonlocal anomalous Hall effect in ternary alloys based on noble metals

    NASA Astrophysics Data System (ADS)

    Töpler, Franziska; Hönemann, Albert; Tauber, Katarina; Fedorov, Dmitry V.; Gradhand, Martin; Mertig, Ingrid; Fert, Albert

    2016-10-01

    We present a theoretical study of the nonlocal anomalous Hall effect induced by heavy-metal impurities in dilute magnetic alloys based on noble metals. The results of our first-principles calculations are shown in comparison to those obtained within a model consideration via Matthiessen's rule. Based on the transport properties of the constituent binary alloys, we reveal optimal host-impurity combinations to enhance the phenomenon. In particular, this allows us to explain experimental findings showing a strong effect in Cu-based alloys but a vanishing effect in the case of the Au host.

  15. Ice Ih anomalies: Thermal contraction, anomalous volume isotope effect, and pressure-induced amorphization

    NASA Astrophysics Data System (ADS)

    Salim, Michael A.; Willow, Soohaeng Yoo; Hirata, So

    2016-05-01

    Ice Ih displays several anomalous thermodynamic properties such as thermal contraction at low temperatures, an anomalous volume isotope effect (VIE) rendering the volume of D2O ice greater than that of H2O ice, and a pressure-induced transition to the high-density amorphous (HDA) phase. Furthermore, the anomalous VIE increases with temperature, despite its quantum-mechanical origin. Here, embedded-fragment ab initio second-order many-body perturbation (MP2) theory in the quasiharmonic approximation (QHA) is applied to the Gibbs energy of an infinite, proton-disordered crystal of ice Ih at wide ranges of temperatures and pressures. The quantum effect of nuclei moving in anharmonic potentials is taken into account from first principles without any empirical or nonsystematic approximation to either the electronic or vibrational Hamiltonian. MP2 predicts quantitatively correctly the thermal contraction at low temperatures, which is confirmed to originate from the volume-contracting hydrogen-bond bending modes (acoustic phonons). It qualitatively reproduces (but underestimates) the thermal expansion at higher temperatures, caused by the volume-expanding hydrogen-bond stretching (and to a lesser extent librational) modes. The anomalous VIE is found to be the result of subtle cancellations among closely competing isotope effects on volume from all modes. Consequently, even ab initio MP2 with the aug-cc-pVDZ and aug-cc-pVTZ basis sets has difficulty reproducing this anomaly, yielding qualitatively varied predictions of the sign of the VIE depending on such computational details as the choice of the embedding field. However, the temperature growth of the anomalous VIE is reproduced robustly and is ascribed to the librational modes. These solid-state MP2 calculations, as well as MP2 Born-Oppenheimer molecular dynamics, find a volume collapse and a loss of symmetry and long-range order in ice Ih upon pressure loading of 2.35 GPa or higher. Concomitantly, rapid softening of

  16. Vehicle effects on human stratum corneum absorption and skin penetration.

    PubMed

    Zhang, Alissa; Jung, Eui-Chang; Zhu, Hanjiang; Zou, Ying; Hui, Xiaoying; Maibach, Howard

    2016-07-19

    This study evaluated the effects of three vehicles-ethanol (EtOH), isopropyl alcohol (IPA), and isopropyl myristate (IPM)-on stratum corneum (SC) absorption and diffusion of the [(14)C]-model compounds benzoic acid and butenafine hydrochloride to better understand the transport pathways of chemicals passing through and resident in SC. Following application of topical formulations to human dermatomed skin for 30 min, penetration flux was observed for 24 h post dosing, using an in vitro flow-through skin diffusion system. Skin absorption and penetration was compared to the chemical-SC (intact, delipidized, or SC lipid film) binding levels. A significant vehicle effect was observed for chemical skin penetration and SC absorption. IPA resulted in the greatest levels of intact SC/SC lipid absorption, skin penetration, and total skin absorption/penetration of benzoic acid, followed by IPM and EtOH, respectively. For intact SC absorption and total skin absorption/penetration of butenafine, the vehicle that demonstrated the highest level of sorption/penetration was EtOH, followed by IPA and IPM, respectively. The percent doses of butenafine that were absorbed in SC lipid film and penetrated through skin in 24 h were greatest for IPA, followed by EtOH and IPM, respectively. The vehicle effect was consistent between intact SC absorption and total chemical skin absorption and penetration, as well as SC lipid absorption and chemical penetration through skin, suggesting intercellular transport as a main pathway of skin penetration for model chemicals. These results suggest the potential to predict vehicle effects on skin permeability with simple SC absorption assays. As decontamination was applied 30 min after chemical exposure, significant vehicle effects on chemical SC partitioning and percutaneous penetration also suggest that skin decontamination efficiency is vehicle dependent, and an effective decontamination method should act on chemical solutes in the lipid domain.

  17. Absence of the Thermal Hall Effect in Anomalous Nernst and Spin Seebeck Effects.

    PubMed

    Chen, Yi-Jia; Huang, Ssu-Yen

    2016-12-09

    The anomalous Nernst effect (ANE) and the spin Seebeck effect (SSE) in spin caloritronics are two of the most important mechanisms to manipulate the spin-polarized current and pure spin current by thermal excitation. While the ANE in ferromagnetic metals and the SSE in magnetic insulators have been extensively studied, a recent theoretical work suggests that the signals from the thermal Hall effect (THE) have field dependences indistinguishable from, and may even overwhelm, those of the ANE and SSE. Therefore, it is vital to investigate the contribution of the THE in the ANE and SSE. In this work, we systematically study the THE in a ferromagnetic metal, Permalloy (Py), and magnetic insulator, an yttrium iron garnet (YIG), by using different Seebeck coefficients between electrodes and contact wires. Our results demonstrate that the contribution of the THE by the thermal couple effect in the Py and YIG is negligibly small if one includes the thickness dependence of the Seebeck coefficient. Thus, the spin-polarized current in the ANE and the pure spin current in the SSE remain indispensable for exploring spin caloritronics phenomena.

  18. Absence of the Thermal Hall Effect in Anomalous Nernst and Spin Seebeck Effects

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Jia; Huang, Ssu-Yen

    2016-12-01

    The anomalous Nernst effect (ANE) and the spin Seebeck effect (SSE) in spin caloritronics are two of the most important mechanisms to manipulate the spin-polarized current and pure spin current by thermal excitation. While the ANE in ferromagnetic metals and the SSE in magnetic insulators have been extensively studied, a recent theoretical work suggests that the signals from the thermal Hall effect (THE) have field dependences indistinguishable from, and may even overwhelm, those of the ANE and SSE. Therefore, it is vital to investigate the contribution of the THE in the ANE and SSE. In this work, we systematically study the THE in a ferromagnetic metal, Permalloy (Py), and magnetic insulator, an yttrium iron garnet (YIG), by using different Seebeck coefficients between electrodes and contact wires. Our results demonstrate that the contribution of the THE by the thermal couple effect in the Py and YIG is negligibly small if one includes the thickness dependence of the Seebeck coefficient. Thus, the spin-polarized current in the ANE and the pure spin current in the SSE remain indispensable for exploring spin caloritronics phenomena.

  19. Effect of extended confinement on the structure of edge channels in the quantum anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Yue, Z.; Raikh, M. E.

    2016-09-01

    The Quantum anomalous Hall (QAH) effect in the films with nontrivial band structure accompanies the ferromagnetic transition in the system of magnetic dopants. Experimentally, the QAH transition manifests itself as a jump in the dependence of longitudinal resistivity on a weak external magnetic field. Microscopically, this jump originates from the emergence of a chiral edge mode on one side of the ferromagnetic transition. We study analytically the effect of an extended confinement on the structure of the edge modes. We employ the simplest model of the extended confinement in the form of a potential step next to the hard wall. It is shown that, unlike the conventional quantum Hall effect, where all edge channels are chiral, in the QAH effect, a complex structure of the boundary leads to nonchiral edge modes which are present on both sides of the ferromagnetic transition. Wave functions of nonchiral modes are different above and below the transition: on the "topological" side, where the chiral edge mode is supported, nonchiral modes are "repelled" from the boundary; i.e., they are much less localized than on the "trivial" side. Thus, the disorder-induced scattering into these modes will boost the extension of the chiral edge mode. The prime experimental manifestation of nonchiral modes is that, by contributing to longitudinal resistance, they smear the QAH transition.

  20. Anomalous effect of trench-oxide depth on alpha-particle-induced charge collection

    SciTech Connect

    Shin, H.; Kim, N.M.

    1999-06-01

    The effect of trench-oxide depth on the alpha-particle-induced charge collection is analyzed for the first time. From the simulation results, it was found that the depth of trench oxide has a considerable influence on the amount of collected charge. The confining of generated charge by the trench oxide was identified as a cause of this anomalous effect. Therefore, the tradeoff between soft error rate and cell to cell isolation characteristics should be considered in optimizing the depth of trench oxide.

  1. Enhancement of anomalous Nernst effects in metallic multilayers free from proximity-induced magnetism

    NASA Astrophysics Data System (ADS)

    Uchida, Ken-ichi; Kikkawa, Takashi; Seki, Takeshi; Oyake, Takafumi; Shiomi, Junichiro; Qiu, Zhiyong; Takanashi, Koki; Saitoh, Eiji

    2015-09-01

    The anomalous Nernst effect (ANE) has been investigated in alternately stacked multilayer films comprising paramagnetic and ferromagnetic metals. We found that the ANE is enhanced by increasing the number of the paramagnet/ferromagnet interfaces and keeping the total thickness of the films constant, and that the enhancement appears even in the absence of magnetic proximity effects; similar behavior was observed not only in Pt/Fe multilayers but also in Au/Fe and Cu/Fe multilayers free from proximity ferromagnetism. This universal enhancement of the ANE in metallic multilayers suggests the presence of unconventional interface-induced thermoelectric conversion in the Fe films attached to the paramagnets.

  2. Localization Correction to Anomalous Hall Effect in the Perpendicular CoFeB Thin Films

    NASA Astrophysics Data System (ADS)

    Ding, Jinjun; Yang, Xiaofei; Zhu, Tao

    2015-12-01

    In this paper, we reported an obvious weak localization (WL) effect in perpendicular CoFeB sandwiched by Ta and MgO layers. The WL correction to the anomalous Hall effect (AHE) arises when the sheet resistance is larger than 1.5kΩ. Furthermore, it is found that the mechanism of AHE is strongly related to the characteristic of the granularity in the MgO/CoFeB/Ta thin films. Both skew scattering and side jump mechanisms will give comparable contribution in the high disorder regime.

  3. Caffeine effects on resting-state electrodermal levels in AD/HD suggest an anomalous arousal mechanism.

    PubMed

    Barry, Robert J; Clarke, Adam R; McCarthy, Rory; Selikowitz, Mark; MacDonald, Brett; Dupuy, Franca E

    2012-03-01

    The effect of a single oral dose of caffeine was examined in a randomised double-blind placebo-controlled repeated-measures cross-over study. Eighteen children with AD/HD, aged between 8 and 13 years, were individually age- and gender-matched with a control group. All children participated in two sessions, one week apart. Skin conductance level (SCL) from a 3 min eyes-closed epoch, commencing 30 min after ingestion of caffeine or placebo, was examined. Across conditions, mean SCL was lower in the AD/HD group than controls, confirming hypoarousal in AD/HD. Caffeine produced an increase in SCL, and this increase did not differ between the groups. However, arousal increases were dose-dependent in controls, but not in AD/HD. Rather, caffeine-induced arousal increases in the AD/HD group were positively related to their hyperactivity/impulsivity levels. This suggests an anomalous arousal mechanism in AD/HD functionally related to impairment in one symptom dimension.

  4. Ordinary and anomalous Hall effects of ferromagnetic Mn5Ge3

    NASA Astrophysics Data System (ADS)

    Zeng, Changgan

    2007-03-01

    It is well know that in ferromagnetic materials, the Hall effect includes two contributions: the ordinary Hall effect (OHE), which is proportional to the applied magnetic field, and the anomalous Hall effect (AHE), which originates from the magnetization of the material. Although both phenomena have been throughly studied, there are still questions about the origins of both OHE and AHE in ferromagnetic materials with complicated band structures. Using ferromagnetic Mn5Ge3 thin films as an example, we investigate the Hall effect experimentally and theoretically. We have separated the intrinsic and extrinsic contributions to the experimental AHE and calculated the intrinsic anomalous Hall conductivity from the Berry curvature of the Bloch states using first-principles methods. The intrinsic anomalous Hall conductivity depends linearly on the magnetization, which can be understood from the long-wavelength fluctuations of the spin orientation at finite temperatures. The quantitative agreement between theory and experiment is remarkably good, not only near 0 K but also at finite temperatures, up to about 240 K (0.8Tc) [1]. The measured ordinary Hall coefficient is found to change its sign as a function of temperature. From a detailed analysis, which includes magneto-resistance measurements, magnetic characterization, and first-principles calculations, we establish that the sign change of the OHE is mainly caused by the mixing of the AHE with the magneto-resistance and differential susceptibility. This work was done in collaboration with Y. Yao, Di Xiao, Q. Niu, and H.H. Weitering. [1] Changgan Zeng, Yugui Yao, Qian Niu, and Hanno, H. Weitering, Phys. Rev. Lett. 96, 037204 (2006).

  5. Evaluating a heated metal scrubber's effectiveness in preventing ozone monitors' anomalous behavior during hot and humid ambient sampling

    SciTech Connect

    Maddy, J.A.

    1999-07-01

    The purpose of this paper is to verify West Virginia's Wet/Dry test's prediction that Advanced Pollution Instrumentation's (API) ozone monitors, when using a heated metal scrubber in lieu of a standard MnO{sub 2} scrubber, would be made insensitive to sampling conditions which provoke anomalous behavior. Field trials involving two identical API model 400 ozone monitors, a Horiba APOA 360 ozone monitor, MnO{sub 2} scrubbers and API's optional heated metal scrubber would determine this. The heated metal scrubber succeeded in effectively eliminating the anomalous behavior. Evaluation results further verify the accuracy of West Virginia's Wet/Dry test. During the evaluation, a serendipitous event led to observations that confirmed previous observations by The Commonwealth of Virginia's monitoring staff, linking contamination of UV monitors' optics with anomalous behavior. Also, a partial summation of observations concerning ultraviolet ozone monitors' anomalous behavior, drawn from several sources, illustrates its complex nature.

  6. Effects of softened and unsoftened fabrics on sensitive skin.

    PubMed

    Piérard, G E; Arrese, J E; Rodríguez, C; Daskaleros, P A

    1994-05-01

    The effects of softened fabrics on the skin were evaluated by a forearm wet and dry test, under conditions simulating real-life skin contact with fabrics. 15 volunteers with sensitive skin according to dermatological assessment and their own recognition entered a double-blind 12 day, 3 sessions per day, forearm wetting and drying test, using cotton fabrics washed with a powder detergent and softened or not with a liquid fabric conditioner. To simulate conditions of skin damage, a dilute solution of sodium lauryl sulfate was applied under patch to the forearm before the start of the study. Skin effects were evaluated by visual grading (redness, dryness and smoothness), by noninvasive skin stripping and measuring of Chroma C* (squamometry), and by instrumental measurements (capacitance, transepidermal water loss, and colorimetry). Both the unsoftened and softened fabrics induced no deleterious effects on control or previously irritated skin. Furthermore, a mild beneficial effect was observed with the softened fabrics, particularly on previously irritated skin. The study findings suggest that softened fabrics may exert a reduced frictional effect on the skin.

  7. Extremely large magnetoresistance and magnetic logic by coupling semiconductor nonlinear transport effect and anomalous Hall Effect

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaozhong; Luo, Zhaochu

    Size limitation of silicon FET hinders the further scaling down of silicon based CPU. To solve this problem, spin based magnetic logic devices were proposed but almost all of them could not be realized experimentally except for NOT logic operation. A magnetic field controlled reconfigurable semiconductor logic using InSb was reported. However, InSb is very expensive and not compatible with the silicon technology. Based on our Si based magnetoresistance (MR) device, we developed a Si based reconfigurable magnetic logic device, which could do all four Boolean logic operations including AND, OR, NOR and NAND. By coupling nonlinear transport effect of semiconductor and anomalous Hall effect of magnetic material, we propose a PMA material based MR device with a remarkable non local MR of >20000 % at ~1 mT. Based on this MR device, we further developed a PMA material based magnetic logic device which could do all four Boolean logic operations. This makes it possible that magnetic material does both memory and logic. This may result in a memory-logic integrated system leading to a non von Neumann computer

  8. Stacking order dependence of inverse spin Hall effect and anomalous Hall effect in spin pumping experiments

    SciTech Connect

    Kim, Sang-Il; Seo, Min-Su; Park, Seung-Young; Kim, Dong-Jun; Park, Byong-Guk

    2015-05-07

    The dependence of the measured DC voltage on the non-magnetic material (NM) in NM/CoFeB and CoFeB/NM bilayers is studied under ferromagnetic resonance conditions in a TE{sub 011} resonant cavity. The directional change of the inverse spin Hall effect (ISHE) voltage V{sub ISHE} for the stacking order of the bilayer can separate the pure V{sub ISHE} and the anomalous Hall effect (AHE) voltage V{sub AHE} utilizing the method of addition and subtraction. The Ta and Ti NMs show a broad deviation of the spin Hall angle θ{sub ISH}, which originates from the AHE in accordance with the high resistivity of NMs. However, the Pt and Pd NMs show that the kinds of NMs with low resistivity are consistent with the previously reported θ{sub ISH} values. Therefore, the characteristics that NM should simultaneously satisfy to obtain a reasonable V{sub ISHE} value in bilayer systems are large θ{sub ISH} and low resistivity.

  9. Skin moisturizing effects of panthenol-based formulations.

    PubMed

    Camargo, Flávio B; Gaspar, Lorena R; Maia Campos, Patrícia M B G

    2011-01-01

    This study aims to evaluate the skin moisturizing efficacy of formulations containing different concentrations of panthenol. Formulations supplemented with or without 0.5%, 1.0%, or 5.0% panthenol were applied daily to the forearms of healthy subjects. Skin conditions in terms of moisture and transepidermal water loss (TEWL) were analyzed before and after 15- and 30-day periods of application. The formulations were also applied after skin washing with sodium laureth sulphate (SLES) to evaluate the immediate effects on TEWL and skin moisture. Panthenol-containing formulations (1.0% and 5.0%) produced significant decreases in TEWL after 30-day applications. In skin washed with SLES, significant reduction of TEWL was evident two hours after application of formulations loaded with panthenol when compared with control and vehicle. It is concluded that skin integrity is maintained by the improved protective effect of 1.0% panthenol added to the formulation.

  10. Hysteretic magnetoresistance and unconventional anomalous Hall effect in the frustrated magnet TmB4

    NASA Astrophysics Data System (ADS)

    Sunku, Sai Swaroop; Kong, Tai; Ito, Toshimitsu; Canfield, Paul C.; Shastry, B. Sriram; Sengupta, Pinaki; Panagopoulos, Christos

    2016-05-01

    We study TmB4, a frustrated magnet on the Archimedean Shastry-Sutherland lattice, through magnetization and transport experiments. The lack of anisotropy in resistivity shows that TmB4 is an electronically three-dimensional system. The magnetoresistance (MR) is hysteretic at low temperature even though a corresponding hysteresis in magnetization is absent. The Hall resistivity shows unconventional anomalous Hall effect (AHE) and is linear above saturation despite a large MR. We propose that complex structures at magnetic domain walls may be responsible for the hysteretic MR and may also lead to the AHE.

  11. Hysteretic magnetoresistance and unconventional anomalous Hall effect in the frustrated magnet TmB4

    NASA Astrophysics Data System (ADS)

    Sunku, Sai Swaroop; Kong, Tai; Ito, Toshimitsu; Canfield, Paul C.; Shastry, B. Sriram; Sengupta, Pinaki; Panagopoulos, Christos

    We study TmB4, a frustrated magnet on the Archimedean Shastry-Sutherland lattice, through magnetization and transport experiments. The lack of anisotropy in resistivity shows that TmB4 is an electronically three-dimensional system. The magnetoresistance (MR) is hysteretic at low-temperature even though a corresponding hysteresis in magnetization is absent. The Hall resistivity shows unconventional anomalous Hall effect (AHE) and is linear above saturation despite a large MR. We suggest that both hysteretic MR and AHE arise from the formation of complex non-coplanar structures at magnetic domain walls. Current address: Department of Applied Physics and Applied Mathematics, Columbia University.

  12. Hysteretic magnetoresistance and unconventional anomalous Hall effect in the frustrated magnet TmB4

    DOE PAGES

    Sunku, Sai Swaroop; Kong, Tai; Ito, Toshimitsu; ...

    2016-05-11

    We study TmB4, a frustrated magnet on the Archimedean Shastry-Sutherland lattice, through magnetization and transport experiments. The lack of anisotropy in resistivity shows that TmB4 is an electronically three-dimensional system. The magnetoresistance (MR) is hysteretic at low temperature even though a corresponding hysteresis in magnetization is absent. The Hall resistivity shows unconventional anomalous Hall effect (AHE) and is linear above saturation despite a large MR. In conclusion, we propose that complex structures at magnetic domain walls may be responsible for the hysteretic MR and may also lead to the AHE.

  13. Nonadiabatic effects in ultracold molecules via anomalous linear and quadratic Zeeman shifts.

    PubMed

    McGuyer, B H; Osborn, C B; McDonald, M; Reinaudi, G; Skomorowski, W; Moszynski, R; Zelevinsky, T

    2013-12-13

    Anomalously large linear and quadratic Zeeman shifts are measured for weakly bound ultracold 88Sr2 molecules near the intercombination-line asymptote. Nonadiabatic Coriolis coupling and the nature of long-range molecular potentials explain how this effect arises and scales roughly cubically with the size of the molecule. The linear shifts yield nonadiabatic mixing angles of the molecular states. The quadratic shifts are sensitive to nearby opposite f-parity states and exhibit fourth-order corrections, providing a stringent test of a state-of-the-art ab initio model.

  14. Comparison of anomalous Doppler resonance effects with molybdenum and graphite limiters on HT-7.

    PubMed

    Wang, Y M; Gao, X; Ling, B L; Liu, Y; Zhang, S B; Han, X; Ti, A; Li, E Z

    2012-03-01

    The material of limiter in HT-7 tokamak was changed from graphite to molybdenum in the last experimental campaign. The pitch angle scattering of runaway electrons due to anomalous Doppler resonance effects was observed. The experimental results agree very well with the stable boundary condition expected from the linear resistive theory but only agree with that from the nonlinear evolutionary of runaway-electron distribution theory in low electric field region. The current carried by runaway electrons is the same under different limiter conditions.

  15. Comparison of anomalous Doppler resonance effects with molybdenum and graphite limiters on HT-7

    PubMed Central

    Wang, Y. M.; Gao, X.; Ling, B. L.; Liu, Y.; Zhang, S. B.; Han, X.; Ti, A.; Li, E. Z.

    2012-01-01

    The material of limiter in HT-7 tokamak was changed from graphite to molybdenum in the last experimental campaign. The pitch angle scattering of runaway electrons due to anomalous Doppler resonance effects was observed. The experimental results agree very well with the stable boundary condition expected from the linear resistive theory but only agree with that from the nonlinear evolutionary of runaway-electron distribution theory in low electric field region. The current carried by runaway electrons is the same under different limiter conditions. PMID:22509090

  16. Quantum phase transitions and anomalous Hall effect in a pyrochlore Kondo lattice

    NASA Astrophysics Data System (ADS)

    Grefe, Sarah; Ding, Wenxin; Si, Qimiao

    The metallic variant of the pyrochlore iridates Pr2Ir2O7 has shown characteristics of a possible chiral spin liquid state [PRL 96 087204 (2006), PRL 98, 057203 (2007), Nature 463, 210 (2010)] and quantum criticality [Nat. Mater. 13, 356 (2014)]. An important question surrounding the significant anomalous Hall response observed in Pr2Ir2O7 is the nature of the f-electron local moments, including their Kondo coupling with the conduction d-electrons. The heavy effective mass and related thermodynamic characteristics indicate the involvement of the Kondo effect in this system's electronic properties. In this work, we study the effects of Kondo coupling on candidate time-reversal-symmetry-breaking spin liquid states on the pyrochlore lattice. Representing the f-moments as slave fermions Kondo-coupled to conduction electrons, we study the competition between Kondo-singlet formation and chiral spin correlations and determine the zero-temperature phase diagram. We derive an effective chiral interaction between the local moments and the conduction electrons and calculate the anomalous Hall response across the quantum phase transition from the Kondo destroyed phase to the Kondo screened phase. We discuss our results' implications for Pr2Ir2O7 and related frustrated Kondo-lattice systems.

  17. The framing effect and skin conductance responses.

    PubMed

    Ring, Patrick

    2015-01-01

    Individuals often rely on simple heuristics when they face complex choice situations under uncertainty. Traditionally, it has been proposed that cognitive processes are the main driver to evaluate different choice options and to finally reach a decision. Growing evidence, however, highlights a strong interrelation between judgment and decision-making (JDM) on the one hand, and emotional processes on the other hand. This also seems to apply to judgmental heuristics, i.e., decision processes that are typically considered to be fast and intuitive. In this study, participants are exposed to different probabilities of receiving an unpleasant electric shock. Information about electric shock probabilities is either positively or negatively framed. Integrated skin conductance responses (ISCRs) while waiting for electric shock realization are used as an indicator for participants' emotional arousal. This measure is compared to objective probabilities. I find evidence for a relation between emotional body reactions measured by ISCRs and the framing effect. Under negative frames, participants show significantly higher ISCRs while waiting for an electric shock to be delivered than under positive frames. This result might contribute to a better understanding of the psychological processes underlying JDM. Further studies are necessary to reveal the causality underlying this finding, i.e., whether emotional processes influence JDM or vice versa.

  18. The framing effect and skin conductance responses

    PubMed Central

    Ring, Patrick

    2015-01-01

    Individuals often rely on simple heuristics when they face complex choice situations under uncertainty. Traditionally, it has been proposed that cognitive processes are the main driver to evaluate different choice options and to finally reach a decision. Growing evidence, however, highlights a strong interrelation between judgment and decision-making (JDM) on the one hand, and emotional processes on the other hand. This also seems to apply to judgmental heuristics, i.e., decision processes that are typically considered to be fast and intuitive. In this study, participants are exposed to different probabilities of receiving an unpleasant electric shock. Information about electric shock probabilities is either positively or negatively framed. Integrated skin conductance responses (ISCRs) while waiting for electric shock realization are used as an indicator for participants' emotional arousal. This measure is compared to objective probabilities. I find evidence for a relation between emotional body reactions measured by ISCRs and the framing effect. Under negative frames, participants show significantly higher ISCRs while waiting for an electric shock to be delivered than under positive frames. This result might contribute to a better understanding of the psychological processes underlying JDM. Further studies are necessary to reveal the causality underlying this finding, i.e., whether emotional processes influence JDM or vice versa. PMID:26300747

  19. Beneficial effects of softened fabrics on atopic skin.

    PubMed

    Hermanns, J F; Goffin, V; Arrese, J E; Rodriguez, C; Piérard, G E

    2001-01-01

    There is general concern about the possible cutaneous adverse effects of wearing garments treated with household laundry products, particularly on atopic skin. Our objective was to compare softened and non- softened fabrics in a forearm wet and dry test, under conditions simulating real-life conditions. Twenty atopic volunteers entered a single-blind 12-day (3 sessions per day) forearm wetting and drying test. Cotton fabrics were machine washed and liquid fabric conditioner was added or not to the final rinse. To simulate conditions of skin damage, a dilute solution of sodium lauryl sulphate was applied under occlusion to the forearm of each volunteer before the start of the study. Skin effects were evaluated by visual grading (redness, dryness and smoothness), squamometry and in vivo instrumental measurements (capacitance, transepidermal water loss and colorimetry). Rubbing of atopic skin with fabrics generally resulted in discrete to moderate alterations of the structure of the stratum corneum. Both for control and pre-irritated skin, all measured parameters indicated that softened fabric was less aggressive to the skin than unsoftened fabric. In the case of pre-irritated skin, the recovery of the skin was significantly faster when rubbed with softened than with unsoftened fabrics. In conclusion, softened fabrics help mitigate the skin condition in atopic patients.

  20. Quantum Anomalous Hall Effect in Low-buckled Honeycomb Lattice with In-plane Magnetization

    NASA Astrophysics Data System (ADS)

    Ren, Yafei; Pan, Hui; Yang, Fei; Li, Xin; Qiao, Zhenhua; Zhenhua Qiao's Group Team; Hui Pan's Group Team

    With out-of-plane magnetization, the quantum anomalous Hall effect has been extensively studied in quantum wells and two-dimensional atomic crystal layers. Here, we investigate the possibility of realizing quantum anomalous Hall effect (QAHE) in honeycomb lattices with in-plane magnetization. We show that the QAHE can only occur in low-buckled honeycomb lattice where both intrinsic and intrinsic Rashba spin-orbit coupling appear spontaneously. The extrinsic Rashba spin-orbit coupling is detrimental to this phase. In contrast to the out-of-plane magnetization induced QAHE, the QAHE from in-plane magnetization is achieved in the vicinity of the time reversal symmetric momenta at M points rather than Dirac points. In monolayer case, the QAHE can be characterized by Chern number  = +/- 1 whereas additional phases with Chern number  = +/- 2 appear in chiral stacked bilayer system. The Chern number strongly depends on the orientation of the magnetization. The bilayer system also provides additional tunability via out-of-plane electric field, which can reduce the critical magnetization strength required to induce QAHE. It can also lead to topological phase transitions from  = +/- 2 to +/- 1 and finally to 0 Equal contribution from Yafei Ren and Hui Pan.

  1. Large anomalous Hall effect in Pt interfaced with perpendicular anisotropy ferrimagnetic insulator

    NASA Astrophysics Data System (ADS)

    Tang, Chi; Sellappan, Pathikumar; Liu, Yawen; Garay, Javier; Shi, Jing; Shines Team

    We demonstrate the strain induced perpendicular magnetic anisotropy (PMA) in a ferrimagnetic insulator (FMI), Tm3Fe5O12 (TIG) and the first observation of large anomalous Hall effect (AHE) in TIG/Pt bilayers. Atomically flat TIG films were deposited by a laser molecular beam epitaxy system on (111)-orientated substituted gadolinium gallium garnet substrates. The strength of PMA could be effectively tuned by controlling the oxygen pressure during deposition. Sharp squared anomalous Hall hysteresis loops were observed in bilayers of TIG/Pt over a range of thicknesses of Pt, with the maximum AHE conductivity reaching 1 S/cm at room temperature. The AHE vanishes when a 5 nm Cu layer was inserted between Pt and TIG, strongly indicating the proximity-induced ferromagnetism in Pt. The large AHE in the bilayer structures demonstrates a potential use of PMA-FMI related heterostructures in spintronics. This work was supported as part of the SHINES, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # SC0012670.

  2. Manipulating dispersive wave generation by anomalous self-steepening effect in metamaterials.

    PubMed

    Xiang, Yuanjiang; Wu, Jipeng; Dai, Xiaoyu; Wen, Shuangchun; Guo, Jun; Wang, Qingkai

    2012-11-19

    We present a theoretical investigation of dispersive wave (DW) generation in nonlinear metamaterials (MMs). The role of the anomalous self-steepening (SS) effect, which can be either positive or negative, and the negative SS parameter can have a very large value compared to an ordinary positive-index material, in DW generation is particularly identified. It is demonstrated that the SS effect exerts a great impact on the peak power while has little effect on the frequency shift of DW. For positive third-order dispersion (TOD), the negative SS broadens the pulse spectrum and weakens the DW's peak power significantly, opposite to the case of positive SS. For negative TOD, however, the negative SS narrows the pulse spectrum and enhances the DW's peak power, also opposite to the case of positive SS. The results suggest that the DW generation in nonlinear MMs can be manipulated by SS effect to a large extent.

  3. Anomalous Hall effect in the prospective spintronic material Eu1-x Gd x O integrated with Si.

    PubMed

    Parfenov, Oleg E; Averyanov, Dmitry V; Tokmachev, Andrey M; Taldenkov, Alexander N; Storchak, Vyacheslav G

    2016-06-08

    Remarkable properties of EuO make it a versatile spintronic material. Despite numerous experimental and theoretical studies of EuO, little is known about the anomalous Hall effect in this ferromagnet. So far, the effect has not been observed in bulk EuO, though has been detected in EuO films with uncontrolled distribution of defects. In the present work doping is taken under control: epitaxial films of Gd-doped EuO are synthesized integrated with Si using molecular beam epitaxy and characterized with x-ray diffraction and magnetization measurements. Nanoscale transport studies reveal the anomalous Hall effect in the ferromagnetic region for samples with different Gd concentration. The saturated anomalous Hall effect conductivity value of 5.0 S·cm(-1) in Gd-doped EuO is more than an order of magnitude larger than those reported so far for Eu chalcogenides doped with anion vacancies.

  4. Magnetoresistance generated from charge-spin conversion by anomalous Hall effect in metallic ferromagnetic/nonmagnetic bilayers

    NASA Astrophysics Data System (ADS)

    Taniguchi, Tomohiro

    2016-11-01

    A theoretical formulation of magnetoresistance effect in a metallic ferromagnetic/nonmagnetic bilayer originated from the charge-spin conversion by the anomalous Hall effect is presented. Analytical expressions of the longitudinal and transverse resistivities in both nonmagnet and ferromagnet are obtained by solving the spin diffusion equation. The magnetoresistance generated from charge-spin conversion purely caused by the anomalous Hall effect in the ferromagnet is found to be proportional to the square of the spin polarizations in the ferromagnet and has fixed sign. We also find additional magnetoresistances in both nonmagnet and ferromagnet arising from the mixing of the spin Hall and anomalous Hall effects. The sign of this mixing resistance depends on those of the spin Hall angle in the nonmagnet and the spin polarizations of the ferromagnet.

  5. Local effect of compression stockings on skin microcirculatory activity through the measurement of skin effective thermal conductivity.

    PubMed

    Grenier, Etienne; Gehin, Claudine; Lun, Bertrand; McAdams, Eric

    2013-01-01

    This paper presents a preliminary study to demonstrate the instantaneous local effect of compression stocking (Class 2) on skin microcirculatory activity. The measurement needs to be carefully performed as the sensor is placed under the garment. To assess the local effect of compression stockings, we use the ambulatory device Hematron located on the calf under the garment. Skin microcirculatory activity is assessed through the skin's effective thermal conductivity measurement. A specific housing for the sensor has been designed to avoid excessive pressure induced by the sensor when squeezed by stockings. The experiment, conducted on ten healthy subjects, comprised two stages: without and with compression stockings. Skin effective thermal conductivity was recorded at three successive positions (supine, sitting and standing). Significant improvement in skin microcirculatory activity was recorded by the Hematron device for the three positions. We have also demonstrated that Hematron sensor can be used under compression stockings.

  6. Calendula extract: effects on mechanical parameters of human skin.

    PubMed

    Akhtar, Naveed; Zaman, Shahiq Uz; Khan, Barkat Ali; Amir, Muhammad Naeem; Ebrahimzadeh, Muhammad Ali

    2011-01-01

    The aim of this study was to evaluate the effects of newly formulated topical cream of Calendula officinalis extract on the mechanical parameters of the skin by using the cutometer. The Cutometer 580 MPA is a device that is designed to measure the mechanical properties of the skin in response to the application of negative pressure. This non-invasive method can be useful for objective and quantitative investigation of age related changes in skin, skin elasticity, skin fatigue, skin hydration, and evaluation of the effects of cosmetic and antiaging topical products. Two creams (base and formulation) were prepared for the study. Both the creams were applied to the cheeks of 21 healthy human volunteers for a period of eight weeks. Every individual was asked to come on week 1, 2, 3, 4, 5, 6, 7, and 8 and measurements were taken by using Cutometer MPA 580 every week. Different mechanical parameters of the skin measured by the cutometer were; R0, R1, R2, R5, R6, R7, and R8. These were then evaluated statistically to measure the effects produced by these creams. Using ANOVA, and t-test it was found that R0, and R6 were significant (p <0.05) whereas R1, R2, R5, R7, R8 were insignificant (p > 0.05). The instrumental measurements produced by formulation reflected significant improvements in hydration and firmness of skin.

  7. Assessing the effects of timing irregularities on radio pulsars anomalous braking indices

    NASA Astrophysics Data System (ADS)

    Chukwude, A. E.; Chidi Odo, Finbarr

    2016-10-01

    We investigate the statistical effects of non-discrete timing irregularities on observed radio pulsar braking indices using correlations between the second derivative of the measured anomalous frequency (̈νobs) and some parameters that have been widely used to quantify pulsar timing fluctuations (the timing activity parameter (A), the amount of timing fluctuations absorbed by the cubic term (σR23) and a measure of pulsar rotational stability (σz)) in a large sample of 366 Jodrell Bank Observatory radio pulsars. The result demonstrates that anomalous braking indices are largely artifacts produced by aggregations of fluctuations that occur within or outside the pulsar system. For a subsample of 223 normal radio pulsars whose observed timing activity appeared consistent with instabilities in rotation of the underlying neutron stars (or timing noise) over timescales of ˜ 10 - 40 yr, |̈νobs| strongly correlates (with correlation coefficient |r| ˜ 0.80 - 0.90) with the pulsar timing activity parameters and spin-down properties. On the other hand, no meaningful correlations (r < 0.3) were found between ̈νobs and the timing activity diagnostics and spin-down parameters in the remaining 143 objects, whose timing activity appears significantly dominated by white noise fluctuations. The current result can be better understood if the timing noise in isolated pulsars originates from intrinsic spin-down processes of the underlying neutron stars, but white noise fluctuations largely arise from processes external to the pulsar system.

  8. Geometric Effect on Quantum Anomalous Hall State in Magnetic Topological Insulator

    NASA Astrophysics Data System (ADS)

    Xing, Yanxia

    An intriguing observation on the quantum anomalous Hall (QAH) effect in a magnetic topological insulator (MTI) is the dissipative edge states. With the aid of non-equilibrium Green's functions,the QAH effect in an MTI with a three dimensional effective tight-binding model is studied.We predict that due to geometric structure in the third dimension z,the unideal contact between terminal leads and central scattering region induces the backscattering in the central Hall bar,as the function of split gates. Such backscattering leads to a nonzero longitudinal resistance and quantized Hall resistance, which would explain the dissipative edge states in experiments.A further numerical simulation prove above prediction as well.These results are rewarding on future experimental observations and transport calculations based on first principe.

  9. Anomalous photovoltaic effect in organic-inorganic hybrid perovskite solar cells

    PubMed Central

    Yuan, Yongbo; Li, Tao; Wang, Qi; Xing, Jie; Gruverman, Alexei; Huang, Jinsong

    2017-01-01

    Organic-inorganic hybrid perovskites (OIHPs) have been demonstrated to be highly successful photovoltaic materials yielding very-high-efficiency solar cells. We report the room temperature observation of an anomalous photovoltaic (APV) effect in lateral structure OIHP devices manifested by the device’s open-circuit voltage (VOC) that is much larger than the bandgap of OIHPs. The persistent VOC is proportional to the electrode spacing, resembling that of ferroelectric photovoltaic devices. However, the APV effect in OIHP devices is not caused by ferroelectricity. The APV effect can be explained by the formation of tunneling junctions randomly dispersed in the polycrystalline films, which allows the accumulation of photovoltage at a macroscopic level. The formation of internal tunneling junctions as a result of ion migration is visualized with Kelvin probe force microscopy scanning. This observation points out a new avenue for the formation of large and continuously tunable VOC without being limited by the materials’ bandgap. PMID:28345043

  10. Quantized topological magnetoelectric effect of the zero-plateau quantum anomalous Hall state

    DOE PAGES

    Wang, Jing; Lian, Biao; Qi, Xiao-Liang; ...

    2015-08-10

    The topological magnetoelectric effect in a three-dimensional topological insulator is a novel phenomenon, where an electric field induces a magnetic field in the same direction, with a universal coefficient of proportionality quantized in units of $e²/2h$. Here in this paper, we propose that the topological magnetoelectric effect can be realized in the zero-plateau quantum anomalous Hall state of magnetic topological insulators or a ferromagnet-topological insulator heterostructure. The finite-size effect is also studied numerically, where the magnetoelectric coefficient is shown to converge to a quantized value when the thickness of the topological insulator film increases. We further propose a device setupmore » to eliminate nontopological contributions from the side surface.« less

  11. Quantized topological magnetoelectric effect of the zero-plateau quantum anomalous Hall state

    SciTech Connect

    Wang, Jing; Lian, Biao; Qi, Xiao-Liang; Zhang, Shou-Cheng

    2015-08-10

    The topological magnetoelectric effect in a three-dimensional topological insulator is a novel phenomenon, where an electric field induces a magnetic field in the same direction, with a universal coefficient of proportionality quantized in units of $e²/2h$. Here in this paper, we propose that the topological magnetoelectric effect can be realized in the zero-plateau quantum anomalous Hall state of magnetic topological insulators or a ferromagnet-topological insulator heterostructure. The finite-size effect is also studied numerically, where the magnetoelectric coefficient is shown to converge to a quantized value when the thickness of the topological insulator film increases. We further propose a device setup to eliminate nontopological contributions from the side surface.

  12. Anomalous photovoltaic effect in organic-inorganic hybrid perovskite solar cells.

    PubMed

    Yuan, Yongbo; Li, Tao; Wang, Qi; Xing, Jie; Gruverman, Alexei; Huang, Jinsong

    2017-03-01

    Organic-inorganic hybrid perovskites (OIHPs) have been demonstrated to be highly successful photovoltaic materials yielding very-high-efficiency solar cells. We report the room temperature observation of an anomalous photovoltaic (APV) effect in lateral structure OIHP devices manifested by the device's open-circuit voltage (VOC) that is much larger than the bandgap of OIHPs. The persistent VOC is proportional to the electrode spacing, resembling that of ferroelectric photovoltaic devices. However, the APV effect in OIHP devices is not caused by ferroelectricity. The APV effect can be explained by the formation of tunneling junctions randomly dispersed in the polycrystalline films, which allows the accumulation of photovoltage at a macroscopic level. The formation of internal tunneling junctions as a result of ion migration is visualized with Kelvin probe force microscopy scanning. This observation points out a new avenue for the formation of large and continuously tunable VOC without being limited by the materials' bandgap.

  13. Anomalous memory effect in the breakdown of low-pressure argon in a long discharge tube

    SciTech Connect

    Meshchanov, A. V.; Korshunov, A. N.; Ionikh, Yu. Z.; Dyatko, N. A.

    2015-08-15

    The characteristics of breakdown of argon in a long tube (with a gap length of 75 cm and diameter of 2.8 cm) at pressures of 1 and 5 Torr and stationary discharge currents of 5–40 mA were studied experimentally. The breakdown was initiated by paired positive voltage pulses with a rise rate of ∼10{sup 8}–10{sup 9} V/s and duration of ∼1–10 ms. The time interval between pairs was varied in the range of Τ ∼ 0.1–1 s, and that between pulses in a pair was varied from τ = 0.4 ms to ≈Τ/2. The aim of this work was to detect and study the so-called “anomalous memory effect” earlier observed in breakdown in nitrogen. The effect consists in the dynamic breakdown voltage in the second pulse in a pair being higher than in the first pulse (in contrast to the “normal” memory effect, in which the relation between the breakdown voltages is opposite). It is found that this effect is observed when the time interval between pairs of pulses is such that the first pulse in a pair is in the range of the normal memory effect of the preceding pair (under the given conditions, Τ ≈ 0.1–0.4 s). In this case, at τ ∼ 10 ms, the breakdown voltage of the second pulse is higher than the reduced breakdown voltage of the first pulse. Optical observations of the ionization wave preceding breakdown in a long tube show that, in the range of the anomalous memory effect and at smaller values of τ, no ionization wave is detected before breakdown in the second pulse. A qualitative interpretation of the experimental results is given.

  14. Protective effects of tea polysaccharides and polyphenols on skin.

    PubMed

    Wei, Xinlin; Liu, Ying; Xiao, Jianbo; Wang, Yuanfeng

    2009-09-09

    The protective effects of tea polysaccharides (TPS) and polyphenols (TPP) on skin were investigated. TPS1 (92% TPS), crude TPS2 (20% TPS), and TPP (98%) were tested. The abilities of TPS and TPP to protect the skin were assessed in four aspects: moisture absorption and retention, sunscreen, promoting the proliferation of fibroblast cells, and tyrosinase inhibitory effect. TPS and TPP absorbed and reserved moisture perfectly. TPS with higher purity had better moisture absorption and retention abilities. TPS1 hardly protected the skin from the sun's ultraviolet (UV) rays and had little promoting effect on fibroblasts proliferation. TPP, however, protected skin against UV rays and enhanced proliferation of fibroblast cells significantly. TPP had good tyrosinase inhibitory effects; TPS showed weaker tyrosinase inhibitory effects with the purity increased. The results indicated that TPP and TPS had complementary advantages and they should be appropriately combined to achieve higher performance when applied as active components of cosmetics.

  15. Anomalous electron heating effects on the E region ionosphere in TIEGCM

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Wang, Wenbin; Oppenheim, Meers; Dimant, Yakov; Wiltberger, Michael; Merkin, Slava

    2016-03-01

    We have recently implemented a new module that includes both the anomalous electron heating and the electron-neutral cooling rate correction associated with the Farley-Buneman Instability (FBI) in the thermosphere-ionosphere electrodynamics global circulation model (TIEGCM). This implementation provides, for the first time, a modeling capability to describe macroscopic effects of the FBI on the ionosphere and thermosphere in the context of a first-principle, self-consistent model. The added heating sources primarily operate between 100 and 130 km altitude, and their magnitudes often exceed auroral precipitation heating in the TIEGCM. The induced changes in E region electron temperature in the auroral oval and polar cap by the FBI are remarkable with a maximum Te approaching 2200 K. This is about 4 times larger than the TIEGCM run without FBI heating. This investigation demonstrates how researchers can add the important effects of the FBI to magnetosphere-ionosphere-thermosphere models and simulators.

  16. The formation of anomalous Hall effect depending on W atoms in ZnO thin films

    NASA Astrophysics Data System (ADS)

    Can, Musa Mutlu; Shah, S. Ismat; Fırat, Tezer

    2014-06-01

    This article investigates the effects of intrinsic point defects and extrinsic W atoms on magneto electrical properties in the ZnO lattice. The analyses were accomplished for ∼0.5% W including ZnO thin films, grown using a radio frequency (RF) magnetron sputtering system. The polarized spin current dependent magnetic formation was investigated by longitudinal and transverse magneto electrical measurements in a temperature range of 5 K to 300 K. The positive magneto resistivity (PMR) ratios reached 28.8%, 12.7%, and 17.6% at 5 K for thin films, having different post-deposition annealing conditions as a consequence of ionic W dependent defects in the lattice. Furthermore, an anomalous Hall effect, originating from polarized spin currents, was understood from the split in Hall resistance versus magnetic field (Rxy(H)) curves for the thin film with high amount of Zn2+ and W6+ ionic defects.

  17. Hysteresis in the anomalous Hall effect of MnAs thin films

    NASA Astrophysics Data System (ADS)

    Jaeckel, Felix T.; Stintz, Andreas; El-Emawy, Abdel-Rahman A.; Malloy, Kevin J.

    2008-03-01

    We report detailed measurements of the Hall effect in MBE-grown MnAs thin films on (001)-GaAs as a function of temperature. Hysteresis of the Hall resistivity is observed for temperatures between 300 and 355 K. Non-linear behavior of the Hall resistivity persists up to 390 K. The appearance of hysteresis at low temperatures can be explained by the emergence of stable, out-of-plane domains due to the shape anisotropy of the contracting α-phase. However, the persistence of the hysteresis and the anomalous Hall effect at temperatures significantly above 318 K is not consistent with the complete transformation of the α-phase and introduces new questions about the magnetic properties of the β-phase.

  18. Evidence for anomalous optical transition radiation linear polarization effects in beam-profile monitors

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; Johnson, A. S.; Ruan, J.; Thurman-Keup, R. M.; Yao, C.-Y.; Evtushenko, P.

    2013-10-01

    Investigations of the effects of optical transition radiation (OTR) polarization components on beam profiles are presented. The transverse profiles are examined using the OTR perpendicular and parallel polarization components with respect to the dimension of interest. We observed ˜15% projected profile size reductions with the perpendicularly polarized components on a 65-μm beam image size case at 14 MeV, a 150-μm beam image size at 4.5 GeV, and a 1100-μm beam image size at 7 GeV. These effects are all several times larger than expected (and anomalous in this sense) when compared to the standard OTR point-spread function calculations. We propose the time-averaged induced-current distribution which generates the OTR represents the actual beam size more faithfully with the perpendicular polarization component and recommend its routine use and subsequent deconvolution.

  19. The quantum anomalous Hall effect on a star lattice with spin-orbit coupling and an exchange field.

    PubMed

    Chen, Mengsu; Wan, Shaolong

    2012-08-15

    We study a star lattice with Rashba spin-orbit coupling and an exchange field and find that there is a quantum anomalous Hall effect in this system, and that there are five energy gaps at Dirac points and quadratic band crossing points. We calculate the Berry curvature distribution and obtain the Hall conductivity (Chern number ν) quantized as integers, and find that ν =- 1,2,1,1,2 when the Fermi level lies in these five gaps. Our model can be viewed as a general quantum anomalous Hall system and, in limit cases, can give what the honeycomb lattice and kagome lattice give. We also find that there is a nearly flat band with ν = 1 which may provide an opportunity for realizing the fractional quantum anomalous Hall effect. Finally, the chiral edge states on a zigzag star lattice are given numerically, to confirm the topological property of this system.

  20. Effect of Systemic Antioxidant Allopurinol Therapy on Skin Flap Survival

    PubMed Central

    Rasti Ardakani, Mehdi; Al-Dam, Ahmed; Rashad, Ashkan; Shayesteh Moghadam, Ali

    2017-01-01

    BACKGROUND It has been reported that systemic administration of allopurinol improves cell survival. This study was aimed to evaluate effects of allopurinol on skin flaps in dogs. METHODS Twenty dogs underwent one skin flap surgery with a 2-week interval. The first procedure was performed according to the standard protocols. The second phase was started by a 1-week pretreatment with allopurinol. Length of the necrotic zone was measured and recorded daily. At each phase, flaps were removed and sent for histopathological study after 1 week observation. RESULTS Mean length of the necrotic zone in allopurinol treated skin flaps has been significantly less than normal flaps over all 7 days of observation (p<0.0001). Histopathology study showed less inflammation and more normal tissue structure in the allopurinol treated skin flaps. CONCLUSION It was demonstrated that systemic administration of allopurinol significantly improved skin flap survival. PMID:28289614

  1. Radiation effects control: Eyes, skin. [space environment simulation

    NASA Technical Reports Server (NTRS)

    Hightower, D.; Smathers, J. B.

    1974-01-01

    Adverse effects on the lens of the eye and the skin due to exposure to proton radiation during manned space flight were evaluated. Actual proton irradiation which might be encountered in space was simulated. Irradiation regimes included single acute exposures, daily fractionated exposures, and weekly fractionated exposures. Animals were exposed and then maintained and examined periodically until data sufficient to meet the objective were obtained. No significant skin effects were noted and no serious sight impairment was exhibited.

  2. Thermal conduction effects in human skin.

    PubMed

    Stoll, A M; Chianta, M A; Piergallini, J R

    1979-08-01

    To determine the maximum permissible temperature any material may attain without causing pain or burn on contact with bare skin, over 2000 observations were made of pain threshold during contact with materials at elevated temperatures. Six materials were used representing the full range of thermal properties from good conductors to good insulators. Time to pain threshold was converted to time to threshold blister on the basis of the relationship between pain and burn established earlier for radiant and for convective heating. Calculated times to blister were used to predict the material temperatures causative of "touch-burn". Experimentally produced threshold blisters at the predicted temperature-times verified the predictions. Graphs and equations were generated for determining safe temperatures for any material in contact with bare skin for 1-5 s solely from a knowledge of its thermal properties. Conversely, the thermal inertia (k rho c) of the optimal material for a specific use and skin contact can be predicted from a knowledge of the maximum material temperature and length of contact time anticipated.

  3. Observation of an anomalous decoherence effect in a quantum bath at room temperature.

    PubMed

    Huang, Pu; Kong, Xi; Zhao, Nan; Shi, Fazhan; Wang, Pengfei; Rong, Xing; Liu, Ren-Bao; Du, Jiangfeng

    2011-12-06

    The decoherence of quantum objects is a critical issue in quantum science and technology. It is generally believed that stronger noise causes faster decoherence. Strikingly, recent theoretical work suggests that under certain conditions, the opposite is true for spins in quantum baths. Here we report an experimental observation of an anomalous decoherence effect for the electron spin-1 of a nitrogen-vacancy centre in high-purity diamond at room temperature. We demonstrate that, under dynamical decoupling, the double-transition can have longer coherence time than the single-transition even though the former couples to the nuclear spin bath as twice strongly as the latter does. The excellent agreement between the experimental and theoretical results confirms the controllability of the weakly coupled nuclear spins in the bath, which is useful in quantum information processing and quantum metrology.

  4. Tuning anomalous Hall effect in perpendicular multilayers with different oxygen environment by interfacial ionic migration

    NASA Astrophysics Data System (ADS)

    Zhang, J. Y.; Sun, Q. Y.; Liu, Y. W.; Peng, W. L.; Wang, F. M.; Pan, Y. D.; Ding, L.; Yu, G. H.

    2017-02-01

    Interfacial oxygen migration and its induced anomalous Hall effect are reported in perpendicular multilayers with different interfacial oxygen-coordinated. Saturation Hall resistance RAH for Pt/Co/MgO/Pt and Pt/Co/Al2O3/Pt multilayers is 3.66 Ω and 4.34 Ω in as-deposited state, respectively. After annealing at 400 °C, RAH value reaches 4.82 Ω and 6.67 Ω, which is 32% and 54% larger than that in as-deposited samples, respectively. Especially, the increment value ΔRAH in Pt/Co/Al2O3/Pt multilayers is 101% larger than that in Pt/Co/MgO/Pt film. Interfacial structural analysis shows such differentΔRAH in two samples originates from distinct oxygen migration behavior induced different interfacial oxygen-coordinated.

  5. Anomalous TWTA output power spikes and their effect on a digital satellite communications system

    NASA Technical Reports Server (NTRS)

    May, Brian D.; Kerczewski, Robert J.; Svoboda, James S.

    1992-01-01

    Several 30 GHz, 60 W traveling wave tube amplifiers (TWTA) were manufactured for the NASA Lewis Research Center's High Burst Rate Link Evaluation Terminal Project. An unusual operating problem characterized by anomalous nonperiodic output power spikes, common to all of the TWTAs proved during testing to significantly affect the performance of a digitally-modulated data transmission test system. Modifications made to the TWTAs significantly curtailed the problem and allowed acceptable system performance to be obtained. This paper presents a discussion of the TWTA output power spike problem, possible causes of the problem, and the solutions implemented by the manufacturer which improved the TWTA performance to an acceptable level. The results of the testing done at NASA Lewis on the TWTAs both before and after the improvement made by Hughes are presented, and the effects of the output power spikes on the performance of the test system are discussed.

  6. Magnetization, anomalous Barkhausen effect, and core loss of Supermendur under high temperature cycling.

    NASA Technical Reports Server (NTRS)

    Niedra, J. M.; Schwarze, G. E.

    1971-01-01

    The magnetization and core loss of Supermendur were measured up to 900 C under conditions of slow temperature cycling in vacuum. As a consequence of this heating, the coercivity at 25 C increased from 21 A/m to about 110 A/m. This increase is less than previously reported. A prominent anomalous Barkhausen effect, pinched-in hysteresis loops, and a magnetic viscosity field in excess of 20 A/m were observed in the range of 600 to 700 C. At 850 C, Supermendur had a coercivity of 23 A/m, a saturation induction exceeding 1.5 T, a core loss of 26 W/kg at 400 Hz, and a maximum induction of 1.5 T. Supermendur may be useful for high temperature soft magnetic material applications where some history dependence of properties and instability of minor loops at lower temperatures is acceptable.

  7. Theory of Multifarious Quantum Phases and Large Anomalous Hall Effect in Pyrochlore Iridate Thin Films.

    PubMed

    Hwang, Kyusung; Kim, Yong Baek

    2016-07-15

    We theoretically investigate emergent quantum phases in the thin film geometries of the pyrochore iridates, where a number of exotic quantum ground states are proposed to occur in bulk materials as a result of the interplay between electron correlation and strong spin-orbit coupling. The fate of these bulk phases as well as novel quantum states that may arise only in the thin film platforms, are studied via a theoretical model that allows layer-dependent magnetic structures. It is found that the magnetic order develop in inhomogeneous fashions in the thin film geometries. This leads to a variety of magnetic metal phases with modulated magnetic ordering patterns across different layers. Both the bulk and boundary electronic states in these phases conspire to promote unusual electronic properties. In particular, such phases are akin to the Weyl semimetal phase in the bulk system and they would exhibit an unusually large anomalous Hall effect.

  8. Quantum anomalous Hall effect in atomic crystal layers from in-plane magnetization

    NASA Astrophysics Data System (ADS)

    Ren, Yafei; Zeng, Junjie; Deng, Xinzhou; Yang, Fei; Pan, Hui; Qiao, Zhenhua

    2016-08-01

    We theoretically demonstrate that with in-plane magnetization, the quantum anomalous Hall effect (QAHE) can be realized in two-dimensional atomic crystal layers with preserved inversion symmetry but broken out-of-plane mirror reflection symmetry. By taking the honeycomb lattice system as an example, we find that the low-buckled structure satisfying the symmetry criteria is crucial to induce QAHE. The topologically nontrivial bulk gap carrying a Chern number of C =±1 opens in the vicinity of the saddle points M , where the band dispersion exhibits strong anisotropy. We further show that the QAHE with electrically tunable Chern number can be achieved in Bernal-stacked multilayer systems, and the applied interlayer potential differences can dramatically decrease the critical magnetization to make the QAHE experimentally feasible.

  9. Theory of Multifarious Quantum Phases and Large Anomalous Hall Effect in Pyrochlore Iridate Thin Films

    NASA Astrophysics Data System (ADS)

    Hwang, Kyusung; Kim, Yong Baek

    2016-07-01

    We theoretically investigate emergent quantum phases in the thin film geometries of the pyrochore iridates, where a number of exotic quantum ground states are proposed to occur in bulk materials as a result of the interplay between electron correlation and strong spin-orbit coupling. The fate of these bulk phases as well as novel quantum states that may arise only in the thin film platforms, are studied via a theoretical model that allows layer-dependent magnetic structures. It is found that the magnetic order develop in inhomogeneous fashions in the thin film geometries. This leads to a variety of magnetic metal phases with modulated magnetic ordering patterns across different layers. Both the bulk and boundary electronic states in these phases conspire to promote unusual electronic properties. In particular, such phases are akin to the Weyl semimetal phase in the bulk system and they would exhibit an unusually large anomalous Hall effect.

  10. Chern half metals: a new class of topological materials to realize the quantum anomalous Hall effect.

    PubMed

    Hu, Jun; Zhu, Zhenyue; Wu, Ruqian

    2015-03-11

    New topological insulators that demonstrate the quantum anomalous Hall effect (QAHE) are a cutting-edge research topic in condensed matter physics and materials science. So far, the QAHE has been observed only in Cr-doped (Bi,Sb)2Te3 at extremely low temperature. Therefore, it is important to find new materials with large topological band gap and high thermal stability for the realization of the QAHE. On the basis of first-principles and tight-binding model calculations, we discovered a new class of topological phase, Chern half metal, which manifests the QAHE in one spin channel while is metallic in the other spin channel, in Co or Rh deposited graphene. The QAHE is robust in these sytems for the adatom coverage ranging from 2% to 6%. Meanwhile, these systems have large perpendicular magnetic anisotropy energies of 5.3 and 11.5 meV, necessary for the observation of the QAHE at reasonably high temperature.

  11. Theory of Multifarious Quantum Phases and Large Anomalous Hall Effect in Pyrochlore Iridate Thin Films

    PubMed Central

    Hwang, Kyusung; Kim, Yong Baek

    2016-01-01

    We theoretically investigate emergent quantum phases in the thin film geometries of the pyrochore iridates, where a number of exotic quantum ground states are proposed to occur in bulk materials as a result of the interplay between electron correlation and strong spin-orbit coupling. The fate of these bulk phases as well as novel quantum states that may arise only in the thin film platforms, are studied via a theoretical model that allows layer-dependent magnetic structures. It is found that the magnetic order develop in inhomogeneous fashions in the thin film geometries. This leads to a variety of magnetic metal phases with modulated magnetic ordering patterns across different layers. Both the bulk and boundary electronic states in these phases conspire to promote unusual electronic properties. In particular, such phases are akin to the Weyl semimetal phase in the bulk system and they would exhibit an unusually large anomalous Hall effect. PMID:27418293

  12. 3d Transition Metal Adsorption Induced the valley-polarized Anomalous Hall Effect in Germanene

    PubMed Central

    Zhou, P.; Sun, L. Z.

    2016-01-01

    Based on DFT + U and Berry curvature calculations, we study the electronic structures and topological properties of 3d transition metal (TM) atom (from Ti to Co) adsorbed germanene (TM-germanene). We find that valley-polarized anomalous Hall effect (VAHE) can be realized in germanene by adsorbing Cr, Mn, or Co atoms on its surface. A finite valley Hall voltage can be easily detected in their nanoribbon, which is important for valleytronics devices. Moreover, different valley-polarized current and even reversible valley Hall voltage can be archived by shifting the Fermi energy of the systems. Such versatile features of the systems show potential in next generation electronics devices. PMID:27312176

  13. Anomalous Hall effect in a ferromagnetic Fe3Sn2 single crystal with a geometrically frustrated Fe bilayer kagome lattice

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Sun, Shanshan; Zhang, Xiao; Pang, Fei; Lei, Hechang

    2016-08-01

    The anomalous Hall effect (AHE) is investigated for a ferromagnetic Fe3Sn2 single crystal with a geometrically frustrated kagome bilayer of Fe. The scaling behavior between anomalous Hall resistivity ρxy A and longitudinal resistivity ρx x is quadratic and further analysis implies that the AHE in the Fe3Sn2 single crystal should be dominated by the intrinsic Karplus-Luttinger mechanism rather than extrinsic skew-scattering or side-jump mechanisms. Moreover, there is a sudden jump of anomalous Hall conductivity σxy A appearing at about 100 K where the spin-reorientation transition from the c axis to the a b plane is completed. This change of σxy A might be related to the evolution of the Fermi surface induced by the spin-reorientation transition.

  14. Influence of disorder on magnetic properties and intrinsic anomalous hall effect in epitaxial Co2FeAl film

    NASA Astrophysics Data System (ADS)

    Meng, K. K.; Miao, J.; Xu, X. G.; Wu, Y.; Zhao, J. H.; Jiang, Y.

    2017-03-01

    We have investigated the influence of disorder on magnetic properties and intrinsic anomalous Hall effects in epitaxial single crystalline full Heusler alloy Co2FeAl. The magnetic properties in both ordered and disordered films are proved by X ray absorption spectroscopy and X ray magnetic circular dichroism measurements. Using a proper scaling, we have extracted the intrinsic anomalous Hall conductivity (AHC) of the films. The intrinsic AHC in the as deposited films is thickness dependent, but in the annealed ones the value is nearly constant, which is ascribed to modified the Fermi surface due to disordering.

  15. Magnetization and anomalous Hall effect in SiO2/Fe/SiO2 trilayers

    NASA Astrophysics Data System (ADS)

    Sekhar Das, Sudhansu; Senthil Kumar, M.

    2017-03-01

    SiO2/Fe/SiO2 sandwich structure films fabricated by sputtering were studied by varying the Fe layer thickness (t Fe). The structural and microstructural studies on the samples showed that the Fe layer has grown in nanocrystalline form with (1 1 0) texture and that the two SiO2 layers are amorphous. Magnetic measurements performed with the applied field in in-plane and perpendicular direction to the film plane confirmed that the samples are soft ferromagnetic having strong in-plane magnetic anisotropy. The temperature dependence of magnetization shows complex behavior with the coexistence of both ferromagnetic and superparamagnetic properties. The transport properties of the samples as studied through Hall effect measurements show anomalous Hall effect (AHE). An enhancement of about 14 times in the saturation anomalous Hall resistance (R\\text{hs}\\text{A} ) was observed upon reducing the t Fe from 300 to 50 Å. The maximum value of R\\text{hs}\\text{A}   =  2.3 Ω observed for t Fe  =  50 Å sample is about 4 orders of magnitude larger than that reported for bulk Fe. When compared with the single Fe film, a maximum increase of about 56% in the R\\text{hs}\\text{A} was observed in sandwiched Fe (50 Å) film. Scaling law suggests that the R s follows the longitudinal resistivity (ρ) as, {{R}\\text{s}}\\propto {ρ1.9} , suggesting side jump as the dominant mechanism of the AHE. A maximum enhancement of about 156% in the sensitivity S was observed.

  16. UV doses and skin effects during psoriasis climate therapy

    NASA Astrophysics Data System (ADS)

    Randeberg, Lise L.; Hernandez-Palacios, Julio; Lilleeng, Mila; Nilsen, Lill Tove; Krogstad, Anne-Lene

    2011-03-01

    Psoriasis is a common autoimmune disease with inflammatory symptoms affecting skin and joints. One way of dealing with psoriasis is by controlled solar UV exposure treatment. However, this treatment should be optimized to get the best possible treatment effect and to limit negative side effects such as erythema and an increased risk of skin cancer. In this study 24 patients at Valle Marina Treatment Center in Gran Canaria were monitored throughout a treatment period of three weeks starting at the beginning of November. The total UV dose to the location was monitored by UV-meters placed on the roof of the treatment centere, and the patients wore individual film dosimeters throughout the treatment period. Skin parameters were accessed by reflection spectroscopy (400-850nm). This paper presents preliminary findings from the skin measurements in the visible part of the spectrum, such as blood oxygenation, erythema and melanin indexes. Reflection spectroscopy was found to be a good tool for such treatment monitoring.

  17. Effect of topically applied lipids on surfactant-irritated skin.

    PubMed

    Lodén, M; Andersson, A C

    1996-02-01

    Moisturizers are used daily by many people to alleviate symptoms of dry skin. All of them contain lipids. It has been suggested that topically applied lipids may interfere with the structure and function of the permeability barrier. The influence of a single application of nine different lipids on normal skin and skin irritated by sodium lauryl sulphate (SLS) was studied in 21 healthy subjects. Parameters assessed were visible signs of irritation, and objectively measured cutaneous blood flow and transepidermal water loss (TEWL). The substances tested were hydrocortisone, petrolatum, fish oil, borage oil, sunflower seed oil, canola oil, shea butter, and fractions of unsaponifiable lipids from canola oil and shea butter. Water was included as a control. On normal skin, no significant differences in the effects of the test substances were found, whereas significant differences were observed when they were applied to SLS-irritated skin. The visible signs of SLS-induced irritation were significantly less pronounced after treatment with the sterol-enriched fraction from canola oil than after treatment with water. This fraction, and hydrocortisone, reduced cutaneous blood flow. Furthermore, application of hydrocortisone, canola oil, and its sterol-enriched fraction, resulted in significantly lower TEWL than with water. The other lipids had no effect on the degree of irritation. In conclusion, lipids commonly used in moisturizers may reduce skin reactions to irritants. Previous studies have shown that, in barrier perturbed skin, the synthesis of sterols is increased. The observed effects of canola oil and its fraction of unsaponifiable lipids on SLS-induced irritation suggest the possibility that they assisted the skin in supplying the damaged barrier with adequate lipids.

  18. Effect of skin wettedness on sweat gland response

    NASA Technical Reports Server (NTRS)

    Nadel, E. R.; Stolwijk, J. A. J.

    1973-01-01

    Investigation of the effect of skin wettedness upon sweating rate. Several techniques were used to gain a better understanding of the quantitative nature of this effect. The results include the finding that the evaporative power of the environment has a profound effect on the relationship between body temperature and sweating rate.

  19. Effects of TLC-Ag dressings on skin inflammation.

    PubMed

    Bisson, Jean-François; Hidalgo-Lucas, Sophie; Bouschbacher, Marielle; Thomassin, Laetitia

    2013-06-01

    The TLC-Ag dressings, a combination of technology lipido-colloid and silver salts, are used to promote healing in wounds with risks or signs of local infection, thanks to the antimicrobial properties of the silver salts. Nanocrystalline silver dressings containing nanocrystalline silver, also used to improve wound healing, present both antimicrobial and anti-inflammatory effects. The aim of this study was to investigate the anti-inflammatory effects of TLC-Ag dressings in a model of chronic skin inflammation induced by repeated application of 12-O-tetradecanoylphorbol-13-acetate to the skin of hairless mice, in comparison with TLC dressing, Silcryst nanocrystalline dressing, desonide cream 0.05%, a corticoid cream used as positive control, and gauze. Daily treatments of the mice began 7 days after the start of induction of chronic skin inflammation and lasted for 7 days. A macroscopic score was performed daily during the treatment period until the mice killing on day 15 and skin samples were taken for histopathological analysis. TLC-Ag reduced significantly the macroscopic score of chronic skin inflammation from day 10 in comparison with gauze and TLC dressing, similarly to Silcryst nanocrystalline dressing and desonide cream, which presented the best anti-inflammatory effects. No significant differences were observed between TLC dressing and gauze. TLC-Ag reduced significantly the microscopic score of chronic skin inflammation in comparison with TLC dressing and gauze, similarly to Silcryst nanocrystalline dressing but significantly less than desonide cream. These results demonstrate that TLC-Ag dressings present significant anti-inflammatory effects on chronic skin inflammation. They can improve wound healing, due to both the antimicrobial and anti-inflammatory properties.

  20. Radon exposure of the skin: I. Biological effects.

    PubMed

    Charles, M W

    2007-09-01

    Radon progeny can plate out on skin and give rise to exposure of the superficial epidermis from alpha emitters Po-218 (7.7 MeV, range approximately 66 microm) and Po-214 (6 MeV, range approximately 44 microm). Dose rates from beta/gamma emitters Pb-214 and Bi-214 are low and only predominate at depths in excess of the alpha range. This paper reviews the evidence for a causal link between exposure from radon and its progeny, and deterministic and stochastic biological effects in human skin. Radiation induced skin effects such as ulceration and dermal atrophy, which require irradiation of the dermis, are ruled out for alpha irradiation from radon progeny because the target cells are considerably deeper than the range of alpha particles. They have not been observed in man or animals. Effects such as erythema and acute epidermal necrosis have been observed in a few cases of very high dose alpha particle exposures in man and after acute high dose exposure in animals from low energy beta radiations with similar depth doses to radon progeny. The required skin surface absorbed doses are in excess of 100 Gy. Such effects would require extremely high levels of radon progeny. They would involve quite exceptional circumstances, way outside the normal range of radon exposures in man. There is no definitive identification of the target cells for skin cancer induction in animals or man. The stem cells in the basal layer which maintain the epidermis are the most plausible contenders for target cells. The majority of these cells are near the end of the range of radon progeny alpha particles, even on the thinnest body sites. The nominal depth of these cells, as recommended by the International Commission on Radiological Protection (ICRP), is 70 microm. There is evidence however that some irradiation of the hair follicles and/or the deeper dermis, as well as the inter-follicular epidermis, is also necessary for skin cancer induction. Alpha irradiation of rodent skin that is

  1. Quantum anomalous Hall effect in time-reversal-symmetry breaking topological insulators

    NASA Astrophysics Data System (ADS)

    Chang, Cui-Zu; Li, Mingda

    2016-03-01

    The quantum anomalous Hall effect (QAHE), the last member of Hall family, was predicted to exhibit quantized Hall conductivity {σyx}=\\frac{{{e}2}}{h} without any external magnetic field. The QAHE shares a similar physical phenomenon with the integer quantum Hall effect (QHE), whereas its physical origin relies on the intrinsic topological inverted band structure and ferromagnetism. Since the QAHE does not require external energy input in the form of magnetic field, it is believed that this effect has unique potential for applications in future electronic devices with low-power consumption. More recently, the QAHE has been experimentally observed in thin films of the time-reversal symmetry breaking ferromagnetic (FM) topological insulators (TI), Cr- and V- doped (Bi,Sb)2Te3. In this topical review, we review the history of TI based QAHE, the route to the experimental observation of the QAHE in the above two systems, the current status of the research of the QAHE, and finally the prospects for future studies.

  2. Anomalous effect of ion velocity on track formation in GeS

    NASA Astrophysics Data System (ADS)

    Szenes, G.; Pécz, B.

    2016-12-01

    Systematic experiments were performed for studying the effect of the projectile velocity (velocity effect, VE) in GeS which has a highly anisotropic conductivity. The prethinned specimens were irradiated by Bi, Au, W, Xe, Ag, Kr, Ni and Fe ions of about E ≈ 1 MeV/nucleon energy. Track radii were measured by transmission electron microscopy. Compared to previous experiments performed with high velocity projectile, there is a marked VE for Se > 20 keV/nm (Se - electronic stopping power). However, the VE is gradually reduced and finally disappears as Se decreases. This effect is described for the first time. The predictions according to the Analytical Thermal Spike Model are in excellent quantitative agreement with the experiments in the range Se > 20 keV/nm. The anomalous behavior of track evolution at lower values of Se is attributed to the combination of semiconducting and insulating properties. An explanation of the VE is given based on the Coulomb explosion model.

  3. Anomalous Hall effect sensors based on magnetic element doped topological insulator thin films

    NASA Astrophysics Data System (ADS)

    Ni, Yan; Zhang, Zhen; Nlebedim, Ikenna; Jiles, David

    Anomalous Hall effect (AHE) is recently discovered in magnetic element doped topological insulators (TIs), which promises low power consumption highly efficient spintronics and electronics. This discovery broaden the family of Hall effect (HE) sensors. In this work, both HE and AHE sensor based on Mn and Cr doped Bi2Te3 TI thin films will be systematically studied. The influence of Mn concentration on sensitivity of MnxBi2-xTe3 HE sensors will be discussed. The Hall sensitivity increase 8 times caused by quantum AHE will be reported. AHE senor based on Cr-doped Bi2Te3 TI thin films will also be studied and compared with Mn doped Bi2Te3 AHE sensor. The influence of thickness on sensitivity of CrxBi2-xTe3 AHE sensors will be discussed. Ultrahigh Hall sensitivity is obtained in Cr doped Bi2Te3. The largest Hall sensitivity can reach 2620 Ω/T in sensor which is almost twice higher than that of the normal semiconductor HE sensor. Our work indicates that magnetic element doped topological insulator with AHE are good candidates for ultra-sensitive Hall effect sensors.

  4. Quantum anomalous Hall effect in time-reversal-symmetry breaking topological insulators.

    PubMed

    Chang, Cui-Zu; Li, Mingda

    2016-03-31

    The quantum anomalous Hall effect (QAHE), the last member of Hall family, was predicted to exhibit quantized Hall conductivity σ(yx) = e2/h without any external magnetic field. The QAHE shares a similar physical phenomenon with the integer quantum Hall effect (QHE), whereas its physical origin relies on the intrinsic topological inverted band structure and ferromagnetism. Since the QAHE does not require external energy input in the form of magnetic field, it is believed that this effect has unique potential for applications in future electronic devices with low-power consumption. More recently, the QAHE has been experimentally observed in thin films of the time-reversal symmetry breaking ferromagnetic (FM) topological insulators (TI), Cr- and V- doped (Bi,Sb)2Te3. In this topical review, we review the history of TI based QAHE, the route to the experimental observation of the QAHE in the above two systems, the current status of the research of the QAHE, and finally the prospects for future studies.

  5. Anomalous Hall effect in Pt thin films induced by ionic gating

    NASA Astrophysics Data System (ADS)

    Shimizu, Sunao; Takahashi, Kei S.; Hatano, Takafumi; Kawasaki, Masashi; Tokura, Yoshinori; Iwasa, Yoshihiro

    2014-03-01

    Pt is an exchange-enhanced paramagnetic material, in which the Stoner criterion for ferromagnetism is nearly satisfied and thus external stimuli may induce unconventional magnetic characteristics. For example, nano-structure formation such as particles[2] or wires[3] provides Pt with ferromagnetic-like properties even at room temperature. In this presentation, we report that a nonmagnetic perturbation in the form of a gate voltage applied through an ionic liquid induces a nonlinear Hall effect in Pt thin films,[4] which resembles the anomalous Hall effect induced by the contact to yttrium iron garnet.[5] Analysis of detailed temperature and magnetic field experiments indicates that the evolution of the nonlinear Hall effect can be explained in terms of large local moments. The applied electric field triggers an electrochemical reaction at the solid/liquid interface and induces magnetic moments as large as ~10 μB that follow the Langevin function. This work was supported by the Japan Society for the Promotion of Science (JSAP) through its `Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program)'.

  6. The foreign exchange market: return distributions, multifractality, anomalous multifractality and the Epps effect

    NASA Astrophysics Data System (ADS)

    Drożdż, Stanisław; Kwapień, Jarosław; Oświȩcimka, Paweł; Rak, Rafał

    2010-10-01

    We present a systematic study of various statistical characteristics of high-frequency returns from the foreign exchange market. This study is based on six exchange rates forming two triangles: EUR-GBP-USD and GBP-CHF-JPY. It is shown that the exchange rate return fluctuations for all of the pairs considered are well described by the non-extensive statistics in terms of q-Gaussians. There exist some small quantitative variations in the non-extensivity q-parameter values for different exchange rates (which depend also on the time scales studied), and this can be related to the importance of a given exchange rate in the world's currency trade. Temporal correlations organize the series of returns such that they develop the multifractal characteristics for all of the exchange rates, with a varying degree of symmetry of the singularity spectrum f(α), however. The most symmetric spectrum is identified for the GBP/USD. We also form time series of triangular residual returns and find that the distributions of their fluctuations develop disproportionately heavier tails as compared to small fluctuations, which excludes description in terms of q-Gaussians. The multifractal characteristics of these residual returns reveal such anomalous properties as negative singularity exponents and even negative singularity spectra. Such anomalous multifractal measures have so far been considered in the literature in connection with diffusion-limited aggregation and with turbulence. Studying the cross-correlations among different exchange rates, we found that market inefficiency on short time scales leads to the occurrence of the Epps effect on much longer time scales, but comparable to the ones for the stock market. Although the currency market is much more liquid than the stock markets and has a much greater transaction frequency, the building up of correlations takes up to several hours—a duration that does not differ much from what is observed in the stock markets. This may suggest

  7. Anomalous spectral response in heterojunction PbTe/PbSnTe infrared detectors - A new effect: Two Peak Effect

    SciTech Connect

    Gong Shuxing; Chen Boliang; Yuan Shixin )

    1991-03-01

    In the measurements of the spectral responses of PbTe/PbSnTe p-n heterojunction infrared detectors, the authors have discovered that there is an anomalous phenomenon in a few detectors when reverse bias is applied: there is not only a response peak in the 8-14 {mu}m long-wavelength range, but also another response peak in the 3-6 {mu}m short-wavelength range. They have also discovered that when reverse bias is increased, the heights of both spectral peaks can be adjusted, and the height of short-wavelength peak may be quickly increased, even if its long-wavelength peak is exceeded. This is an unreported new phenomenon up to now. It is shortly called anomalous phenomenon,' or Two Peak Effect' (TPE). This paper describes the new effect TPE' firstly, and makes a theoretical explanation. On the basis of this effect, it would be possible to make a new type of IR detector, which is quite different from the available detectors.

  8. Switching of a large anomalous Hall effect between metamagnetic phases of a non-collinear antiferromagnet.

    PubMed

    Sürgers, Christoph; Wolf, Thomas; Adelmann, Peter; Kittler, Wolfram; Fischer, Gerda; Löhneysen, Hilbert V

    2017-02-20

    The anomalous Hall effect (AHE), which in long-range ordered ferromagnets appears as a voltage transverse to the current and usually is proportional to the magnetization, often is believed to be of negligible size in antiferromagnets due to their low uniform magnetization. However, recent experiments and theory have demonstrated that certain antiferromagnets with a non-collinear arrangement of magnetic moments exhibit a sizeable spontaneous AHE at zero field due to a non-vanishing Berry curvature arising from the quantum mechanical phase of the electron's wave functions. Here we show that antiferromagnetic Mn5Si3 single crystals exibit a large AHE which is strongly anisotropic and shows multiple transitions with sign changes at different magnetic fields due to field-induced rearrangements of the magnetic structure despite only tiny variations of the total magnetization. The presence of multiple non-collinear magnetic phases offers the unique possiblity to explore the details of the AHE and the sensitivity of the Hall effect on the details of the magnetic texture.

  9. Anomalous Hall effect in Y2Fe17-xCox single crystals

    NASA Astrophysics Data System (ADS)

    Stankiewicz, Jolanta; Skokov, Konstantin

    2009-03-01

    We study experimentally the Hall resistivity of Y2Fe17-xCox single crystals (x<=8) for wide temperature and applied magnetic field ranges, and for various magnetic field orientations with respect to the easy-magnetization axis. We find a large anomalous Hall effect (AHE) anisotropy in this system for x<=2. The AHE resistivity ρxy, measured with an applied magnetic field Hc-axis, is nearly one order of magnitude larger than the one for H along the hard magnetization direction (Hc-axis). Furthermore, the former is very large and varies linearly with the longitudinal resistivity ρ, whereas the latter follows 2̂ for T < 150 K. We tentatively interpret the behavior of ρxy for Hc-axis in terms of an intrinsic effect related to the inter-orbital hopping between degenerate d-orbitals. Such hopping is allowed for high symmetry points at the crystallographic dumb-bell sites in this configuration. On the other hand, there is no inter-orbital hopping for Hc-axis. However, a huge amplitude of the AHE resistivity for this configuration, which follows from skew scattering, is puzzling. Both the AHE anisotropy and the large skew scattering go away as more Fe is substituted by Co. We attribute this to variations in the electronic structure of the Y2Fe17-xCox system when Co atoms start to occupy the dumb-bell crystallographic sites.

  10. Strong and Anomalous Thermal Expansion Precedes the Thermosalient Effect in Dynamic Molecular Crystals

    NASA Astrophysics Data System (ADS)

    Panda, Manas K.; Centore, Roberto; Causà, Mauro; Tuzi, Angela; Borbone, Fabio; Naumov, Panče

    2016-07-01

    The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10‑6 K‑1, αb = 238.8 × 10‑6 K‑1 and αc = ‑290.0 × 10‑6 K‑1, the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously.

  11. Strong and Anomalous Thermal Expansion Precedes the Thermosalient Effect in Dynamic Molecular Crystals.

    PubMed

    Panda, Manas K; Centore, Roberto; Causà, Mauro; Tuzi, Angela; Borbone, Fabio; Naumov, Panče

    2016-07-12

    The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10(-6) K(-1), αb = 238.8 × 10(-6) K(-1) and αc = -290.0 × 10(-6) K(-1), the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously.

  12. Switching of a large anomalous Hall effect between metamagnetic phases of a non-collinear antiferromagnet

    PubMed Central

    Sürgers, Christoph; Wolf, Thomas; Adelmann, Peter; Kittler, Wolfram; Fischer, Gerda; Löhneysen, Hilbert v.

    2017-01-01

    The anomalous Hall effect (AHE), which in long-range ordered ferromagnets appears as a voltage transverse to the current and usually is proportional to the magnetization, often is believed to be of negligible size in antiferromagnets due to their low uniform magnetization. However, recent experiments and theory have demonstrated that certain antiferromagnets with a non-collinear arrangement of magnetic moments exhibit a sizeable spontaneous AHE at zero field due to a non-vanishing Berry curvature arising from the quantum mechanical phase of the electron’s wave functions. Here we show that antiferromagnetic Mn5Si3 single crystals exibit a large AHE which is strongly anisotropic and shows multiple transitions with sign changes at different magnetic fields due to field-induced rearrangements of the magnetic structure despite only tiny variations of the total magnetization. The presence of multiple non-collinear magnetic phases offers the unique possiblity to explore the details of the AHE and the sensitivity of the Hall effect on the details of the magnetic texture. PMID:28218287

  13. Role of band-index-dependent transport relaxation times in anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Xiao, Cong; Li, Dingping; Ma, Zhongshui

    2017-01-01

    We revisit model calculations of the anomalous Hall effect (AHE) and show that, in isotropic Rashba-coupled two-dimensional electron gas with pointlike potential impurities, the full solution of the semiclassical Boltzmann equation (SBE) may differ from the widely used 1 /τ|| and 1 /τ⊥ solution [Schliemann and Loss, Phys. Rev. B 68, 165311 (2003), 10.1103/PhysRevB.68.165311]. Our approach to solving the SBE is consistent with the integral equation approach [Vyborny et al., Phys. Rev. B 79, 045427 (2009), 10.1103/PhysRevB.79.045427] but in the present case, we reduce the description to band-index-dependent transport relaxation times. When both Rashba bands are partially occupied, these are determined by solving a system of linear equations. Detailed calculations show that, for intrinsic and hybrid skew scatterings the difference between 1 /τ|| and 1 /τ⊥ and the full solution of SBE is notable for large Fermi energies. For coordinate-shift effects, the side-jump velocity acquired in the interband elastic-scattering process is shown to be more important for larger Rashba coupling and may even exceed the intraband one for the outer Rashba band. The coordinate-shift contribution to AHE in the considered case notably differs from that in the limit of smooth disorder potential analyzed before.

  14. Switching of a large anomalous Hall effect between metamagnetic phases of a non-collinear antiferromagnet

    NASA Astrophysics Data System (ADS)

    Sürgers, Christoph; Wolf, Thomas; Adelmann, Peter; Kittler, Wolfram; Fischer, Gerda; Löhneysen, Hilbert V.

    2017-02-01

    The anomalous Hall effect (AHE), which in long-range ordered ferromagnets appears as a voltage transverse to the current and usually is proportional to the magnetization, often is believed to be of negligible size in antiferromagnets due to their low uniform magnetization. However, recent experiments and theory have demonstrated that certain antiferromagnets with a non-collinear arrangement of magnetic moments exhibit a sizeable spontaneous AHE at zero field due to a non-vanishing Berry curvature arising from the quantum mechanical phase of the electron’s wave functions. Here we show that antiferromagnetic Mn5Si3 single crystals exibit a large AHE which is strongly anisotropic and shows multiple transitions with sign changes at different magnetic fields due to field-induced rearrangements of the magnetic structure despite only tiny variations of the total magnetization. The presence of multiple non-collinear magnetic phases offers the unique possiblity to explore the details of the AHE and the sensitivity of the Hall effect on the details of the magnetic texture.

  15. Strong and Anomalous Thermal Expansion Precedes the Thermosalient Effect in Dynamic Molecular Crystals

    PubMed Central

    Panda, Manas K.; Centore, Roberto; Causà, Mauro; Tuzi, Angela; Borbone, Fabio; Naumov, Panče

    2016-01-01

    The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10−6 K−1, αb = 238.8 × 10−6 K−1 and αc = −290.0 × 10−6 K−1, the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously. PMID:27403616

  16. Anomalously Large Polarization Effect Responsible for Excitonic Red Shifts in PbSe Quantum Dot Solids

    SciTech Connect

    A Wolcott; V Doyeux; C Nelson; R Gearba; K Lei; K Yager; A dolocan; K Williams; D Nguyen; X Zhu

    2011-12-31

    The formation of solid thin films from colloidal semiconductor quantum dots (QDs) is often accompanied by red shifts in excitonic transitions, but the mechanisms responsible for the red shifts are under debate. We quantitatively address this issue using optical absorption spectroscopy of two-dimensional (2D) and three-dimensional (3D) arrays of PbSe QDs with controlled inter-QD distance, which was determined by the length of alkanedithiol linking molecules. With decreasing inter-QD distance, the first and second exciton absorption peaks show increasing red shifts. Using thin films consisting of large and isolated QDs embedded in a matrix of small QDs, we determine that a dominant contribution to the observed red shift is due to changes in polarization of the dielectric environment surrounding each QD ({approx}88%), while electronic or transition dipole coupling plays a lesser role. However, the observed red shifts are more than 1 order of magnitude larger than theoretical predictions based on the dielectric polarization effect for spherical QDs. We attribute this anomalously large polarization effect to deviations of the exciton wave functions from eigenfunctions of the idealized spherical quantum well model.

  17. Effect of glove occlusion on the skin barrier.

    PubMed

    Tiedemann, Daniel; Clausen, Maja Lisa; John, Swen Malthe; Angelova-Fischer, Irena; Kezic, Sanja; Agner, Tove

    2016-01-01

    Wet work tasks are the most common exposures leading to occupational irritant contact dermatitis. Use of liquid-proof gloves is recommended when performing wet work, however, gloves may also contribute to impairment of the skin barrier and development of irritant contact dermatitis. The aim of this study is to review the literature on the effects of glove occlusion on skin barrier function. The PubMed database was searched up to 1 February 2015 for articles on the association between glove occlusion and skin barrier function, including human studies only and in English. Only experimental studies including assessment of the skin barrier function were included in the data analysis. Thirteen articles were identified, 8 with focus on occlusion alone, 7 with focus on occlusion in combination with irritant exposure (some overlapping), and 2 field studies. In conclusion, data from the literature showed that the negative effect of occlusion in itself is limited, and that only extensive and long-term occlusion will cause barrier impairment. However, studies investigating combined effect of occlusion and exposure to soaps/detergents indicate that occlusion significantly enhances the skin barrier damage caused by detergents/soaps in a dose-response fashion.

  18. Anisotropic Nanomechanics of Boron Nitride Nanotubes: Nanostructured "Skin" Effect

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Menon, Madhu; Cho, KyeongJae

    2000-01-01

    The stiffness and plasticity of boron nitride nanotubes are investigated using generalized tight-binding molecular dynamics and ab-initio total energy methods. Due to boron-nitride BN bond buckling effects, compressed zigzag BN nanotubes are found to undergo novel anisotropic strain release followed by anisotropic plastic buckling. The strain is preferentially released towards N atoms in the rotated BN bonds. The tubes buckle anisotropically towards only one end when uniaxially compressed from both. A "skin-effect" model of smart nanocomposite materials is proposed which will localize the structural damage towards the 'skin' or surface side of the material.

  19. Anomalous Hall effect in MnAl/W bilayers: Modification from strong spin Hall effect of W

    NASA Astrophysics Data System (ADS)

    Meng, K. K.; Miao, J.; Xu, X. G.; Wu, Y.; Zhao, J. H.; Jiang, Y.

    2017-04-01

    We report systematic measurements of anomalous Hall effect (AHE) in MnAl/W bilayers modified by strong spin Hall effect (SHE) of the heavy metals, in which a single L10-MnAl epitaxial layer reveals obvious orbital two-channel Kondo (2CK) effect. The results are compared with the AHE in MnAl/Cu with weak spin orbit coupling. As increasing the thickness of W, the strong SHE has gradually suppressed the orbital 2CK effect and modified the AHE of MnAl. A scaling involving multiple competing scattering mechanisms has been used to distinguish different contributions to the modified AHE. The direct observation of spin-orbit torque induced magnetization switching confirms that the result is a combination of the AHE of MnAl and SHE of W.

  20. Anomalous Hall effect in L 10-MnAl films with controllable orbital two-channel Kondo effect

    NASA Astrophysics Data System (ADS)

    Zhu, L. J.; Nie, S. H.; Zhao, J. H.

    2016-05-01

    The anomalous Hall effect (AHE) in strongly disordered magnetic systems has been buried in persistent confusion despite its long history. We report the AHE in perpendicularly magnetized L 10-MnAl epitaxial films with a variable orbital two-channel Kondo (2CK) effect arising from the strong coupling of conduction electrons and the structural disorders of two-level systems. The AHE is observed to excellently scale with ρAH/f =a0ρx x 0+b ρxx 2 at high temperatures where phonon scattering prevails. In contrast, significant deviation occurs at low temperatures where the orbital 2CK effect becomes important, suggesting a negative AHE contribution. The deviation of the scaling agrees with the orbital 2CK effect in the breakdown temperatures and deviation magnitudes.

  1. Anomalous triple gauge couplings in the effective field theory approach at the LHC

    NASA Astrophysics Data System (ADS)

    Falkowski, Adam; González-Alonso, Martín; Greljo, Admir; Marzocca, David; Son, Minho

    2017-02-01

    We discuss how to perform consistent extractions of anomalous triple gauge couplings (aTGC) from electroweak boson pair production at the LHC in the Standard Model Effective Field Theory (SMEFT). After recasting recent ATLAS and CMS searches in pp → W Z( W W ) → ℓ'νℓ+ℓ-(νℓ) channels, we find that: (a) working consistently at order Λ-2 in the SMEFT expansion the existing aTGC bounds from Higgs and LEP-2 data are not improved, (b) the strong limits quoted by the experimental collaborations are due to the partial Λ-4 corrections (dimension-6 squared contributions). Using helicity selection rule arguments we are able to explain the suppression in some of the interference terms, and discuss conditions on New Physics (NP) models that can benefit from such LHC analyses. Furthermore, standard analyses assume implicitly a quite large NP scale, an assumption that can be relaxed by imposing cuts on the underlying scale of the process ( √{widehat{s}} ). In practice, we find almost no correlation between √{widehat{s}} and the experimentally accessible quantities, which complicates the SMEFT interpretation. Nevertheless, we provide a method to set (conservative) aTGC bounds in this situation, and recast the present searches accordingly. Finally, we introduce a simple NP model for aTGC to compare the bounds obtained directly in the model with those from the SMEFT analysis.

  2. Large anomalous Hall effect in ferromagnetic insulator-topological insulator heterostructures

    SciTech Connect

    Alegria, L. D.; Petta, J. R.; Ji, H.; Cava, R. J.; Yao, N.; Clarke, J. J.

    2014-08-04

    We demonstrate the van der Waals epitaxy of the topological insulator compound Bi{sub 2}Te{sub 3} on the ferromagnetic insulator Cr{sub 2}Ge{sub 2}Te{sub 6}. The layers are oriented with (001)Bi{sub 2}Te{sub 3}||(001)Cr{sub 2}Ge{sub 2}Te{sub 6} and (110)Bi{sub 2}Te{sub 3}||(100)Cr{sub 2}Ge{sub 2}Te{sub 6}. Cross-sectional transmission electron microscopy indicates the formation of a sharp interface. At low temperatures, bilayers consisting of Bi{sub 2}Te{sub 3} on Cr{sub 2}Ge{sub 2}Te{sub 6} exhibit a large anomalous Hall effect (AHE). Tilted field studies of the AHE indicate that the easy axis lies along the c-axis of the heterostructure, consistent with magnetization measurements in bulk Cr{sub 2}Ge{sub 2}Te{sub 6}. The 61 K Curie temperature of Cr{sub 2}Ge{sub 2}Te{sub 6} and the use of near-stoichiometric materials may lead to the development of spintronic devices based on the AHE.

  3. High-Temperature Quantum Anomalous Hall Effect in n -p Codoped Topological Insulators

    NASA Astrophysics Data System (ADS)

    Qi, Shifei; Qiao, Zhenhua; Deng, Xinzhou; Cubuk, Ekin D.; Chen, Hua; Zhu, Wenguang; Kaxiras, Efthimios; Zhang, S. B.; Xu, Xiaohong; Zhang, Zhenyu

    2016-07-01

    The quantum anomalous Hall effect (QAHE) is a fundamental quantum transport phenomenon that manifests as a quantized transverse conductance in response to a longitudinally applied electric field in the absence of an external magnetic field, and it promises to have immense application potential in future dissipationless quantum electronics. Here, we present a novel kinetic pathway to realize the QAHE at high temperatures by n -p codoping of three-dimensional topological insulators. We provide a proof-of-principle numerical demonstration of this approach using vanadium-iodine (V-I) codoped Sb2 Te3 and demonstrate that, strikingly, even at low concentrations of ˜2 % V and ˜1 % I, the system exhibits a quantized Hall conductance, the telltale hallmark of QAHE, at temperatures of at least ˜50 K , which is 3 orders of magnitude higher than the typical temperatures at which it has been realized to date. The underlying physical factor enabling this dramatic improvement is tied to the largely preserved intrinsic band gap of the host system upon compensated n -p codoping. The proposed approach is conceptually general and may shed new light in experimental realization of high-temperature QAHE.

  4. The Anomalous Hall effect in MnSi and FexTaS2

    NASA Astrophysics Data System (ADS)

    Lee, Minhyea

    2007-03-01

    In a high-purity ferromagnet with long carrier lifetime τ, e.g. MnSi, the ordinary Hall conductivity σH^N can dominate the intrinsic Anomalous Hall effect (AHE) conductivity σH^A. We show that the large magnetoresistance provides a way to separate accurately the two Hall currents. Below TC, we find that the AHE conductivity is strictly proportional to the magnetization M, viz. σH^A = SHM with a parameter SH that is independent of both temperature T and field H. This implies that σH^A is strictly independent of τ. In the layered, hard ferromagnet FexTaS2, the large coercivity leads to abrupt reversals of M when it switches. We show that this provides an accurate way to separate σH^A from σH^N. Again, σH^A is independent of T from 5 to 50 K. We compare the observed constancy at low T with theories for the AHE. We also describe a Hall anomaly recently observed in MnSi under pressure. This anomaly appears to arise from strong sensitivity of the Hall current to the spin texture, possibly reflecting its finite chirality. The dependence of the anomaly to T and H will be reported. **This work is done in collaboration with Y. Onose, J. G. Checkelsky, E. Morosan, R. J. Cava, Y. Tokura and N. P. Ong.

  5. Large anomalous Hall effect in a silicon-based magnetic semiconductor.

    PubMed

    Manyala, Ncholu; Sidis, Yvan; DiTusa, John F; Aeppli, Gabriel; Young, David P; Fisk, Zachary

    2004-04-01

    Magnetic semiconductors are attracting great interest because of their potential use for spintronics, a new technology that merges electronics with the manipulation of conduction electron spins. (GaMn)As and (GaMn)N have recently emerged as the most popular materials for this new technology, and although their Curie temperatures are rising towards room temperature, these materials can only be fabricated in thin-film form, are heavily defective, and are not obviously compatible with Si. We show here that it is productive to consider transition metal monosilicides as potential alternatives. In particular, we report the discovery that the bulk metallic magnets derived from doping the narrow-gap insulator FeSi with Co share the very high anomalous Hall conductance of (GaMn)As, while displaying Curie temperatures as high as 53 K. Our work opens up a new arena for spintronics, involving a bulk material based only on transition metals and Si, which displays large magnetic-field effects on its electrical properties.

  6. Magnetic modulation doping in topological insulators toward higher-temperature quantum anomalous Hall effect

    SciTech Connect

    Mogi, M. Yoshimi, R.; Yasuda, K.; Kozuka, Y.; Tsukazaki, A.; Takahashi, K. S.; Kawasaki, M.; Tokura, Y.

    2015-11-02

    Quantum anomalous Hall effect (QAHE), which generates dissipation-less edge current without external magnetic field, is observed in magnetic-ion doped topological insulators (TIs) such as Cr- and V-doped (Bi,Sb){sub 2}Te{sub 3}. The QAHE emerges when the Fermi level is inside the magnetically induced gap around the original Dirac point of the TI surface state. Although the size of gap is reported to be about 50 meV, the observable temperature of QAHE has been limited below 300 mK. We attempt magnetic-Cr modulation doping into topological insulator (Bi,Sb){sub 2}Te{sub 3} films to increase the observable temperature of QAHE. By introducing the rich-Cr-doped thin (1 nm) layers at the vicinity of both the surfaces based on non-Cr-doped (Bi,Sb){sub 2}Te{sub 3} films, we have succeeded in observing the QAHE up to 2 K. The improvement in the observable temperature achieved by this modulation-doping appears to be originating from the suppression of the disorder in the surface state interacting with the rich magnetic moments. Such a superlattice designing of the stabilized QAHE may pave a way to dissipation-less electronics based on the higher-temperature and zero magnetic-field quantum conduction.

  7. Anomalous transport model study of chiral magnetic effects in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Sun, Yifeng; Ko, Che Ming; Li, Feng

    2016-10-01

    Using an anomalous transport model for massless quarks and antiquarks, we study the effect of a magnetic field on the elliptic flows of quarks and antiquarks in relativistic heavy ion collisions. With initial conditions from a blast wave model and assuming that the strong magnetic field produced in noncentral heavy ion collisions can last for a sufficiently long time, we obtain an appreciable electric quadrupole moment in the transverse plane of a heavy ion collision. The electric quadrupole moment subsequently leads to a splitting between the elliptic flows of quarks and antiquarks. The slope of the charge asymmetry dependence of the elliptic flow difference between positively and negatively charged particles is positive, which is expected from the chiral magnetic wave formed in the produced QGP and observed in experiments at the BNL Relativistic Heavy Ion Collider, only if the Lorentz force acting on the charged particles is neglected and the quark-antiquark scattering is assumed to be dominated by the chirality changing channel.

  8. Quantum anomalous Hall effect in magnetically modulated topological insulator/normal insulator heterostructures

    NASA Astrophysics Data System (ADS)

    Men'shov, V. N.; Tugushev, V. V.; Chulkov, E. V.

    2016-10-01

    We theoretically study how magnetic modulation can be used to manipulate the transport properties of heterostructures formed by a thin film of a three-dimensional topological insulator sandwiched between slabs of a normal insulator. Employing the k • p scheme, in the framework of a continual approach, we argue that electron states of the system are spin-polarized when ultrathin magnetic insertions are incorporated into the film. We demonstrate that (i) the spin-polarization magnitude depends strongly on the magnetic insertion position in the film and (ii) there is the optimal insertion position to realize quantum anomalous Hall effect, which is a function of the material parameters, the film thickness and the topological insulator/normal insulator interface potential. For the heterostructure with a pair of symmetrically placed magnetic insertions, we calculate a phase diagram that shows a series of transitions between distinct quantum regimes of transverse conductivity. We provide consistent interpretation of recent experimental findings in the context of our results.

  9. Smearing of the quantum anomalous Hall effect due to statistical fluctuations of magnetic dopants

    NASA Astrophysics Data System (ADS)

    Yue, Z.; Raikh, M. E.

    2016-10-01

    The quantum anomalous Hall effect is induced by substitution of a certain portion x of Bi atoms in a BiTe-based insulating parent compound by magnetic ions (Cr or V). We find the density of in-gap states N (E ) emerging as a result of statistical fluctuations of the composition x in the vicinity of the transition point where the average gap E¯g passes through zero. A local gap follows the fluctuations of x . Using the instanton approach, we show that, near the gap edges, the tails are exponential lnN (E ) ∝-(E¯g-|E |) and the tail states are due to small local gap reduction. Our main finding is that, even when the smearing magnitude exceeds the gap width, there exists a semihard gap around zero energy, where lnN (E ) ∝-E/¯g|E | ln(E/¯g|E | ) . The states responsible for N (E ) originate from local gap reversals within narrow rings. The consequence of the semihard gap is the Arrhenius, rather than variable-range hopping, temperature dependence of the diagonal conductivity at low temperatures.

  10. Quantum anomalous Hall effect with field-tunable Chern number near Z2 topological critical point

    NASA Astrophysics Data System (ADS)

    Duong, Le Quy; Lin, Hsin; Tsai, Wei-Feng; Feng, Yuan Ping

    We study the practicability of achieving quantum anomalous Hall (QAH) effect with field-tunable Chern number in a magnetically doped, topologically trivial insulating thin film. Specifically in a candidate material, TlBi(S1-δSeδ)2, we demonstrate that the QAH phases with different Chern numbers can be achieved by means of tuning the exchange field strength or the sample thickness near the Z2 topological critical point. Our physics scenario successfully reduces the necessary exchange coupling strength for a targeted Chern number. This QAH mechanism differs from the traditional QAH picture with a magnetic topological insulating thin film, where the ``surface'' states must involve and sometimes complicate the realization issue. Furthermore, we find that a given Chern number can also be tuned by a perpendicular electric field, which naturally occurs when a substrate is present. High-Chern number QAH phase obtained from magnetically doped topological crystalline insulator thin films will also be discussed. Support by the Singapore National Research Foundation under NRF Award No. NRF-NRFF2013-03 is acknowledged.

  11. Neutral cloud theory of the Jovian nebula: Anomalous ionization effect of superthermal electrons

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.

    1994-01-01

    The standard model of the Jovian nebula postulates that its particle source is the extended cloud of neutral sulfur and oxygen atoms that escape from the satellite Io and become ionized through electron impact from the corotating plasma. Its energy source is the gyroenergy acquired by newly formed pickup ions as they are swept up to corotation velocity by the planetary magnetic field. Elastic collisions between plasma ions and electrons cool the ions and heat the electrons, while inelastic collisions cool the electrons and excite the ions to radiate intense line emission, which is the primary energy-loss mechanism for the plasma. This neutral cloud theory of the Io plasma torus, as it has come to be known, has been the subject of recent critcism which asserts that the theory cannot account for the observed charge state of the plasma which features O(+) and S(2+) as the dominant ions. It is shown in this work that the inclusion of a small population of super-thermal electrons is required to achieve the correct ion partitioning among various charge states. It is also argued that the anomalous ionization effect of the superthermal electrons is responsible for the overall spatial bifurcation of the nebula into a hot multiply charged plasma region outside of 5.7 Jovian radii and a cool singly ionized plasma inside this distance.

  12. High-Temperature Quantum Anomalous Hall Effect in n-p Codoped Topological Insulators.

    PubMed

    Qi, Shifei; Qiao, Zhenhua; Deng, Xinzhou; Cubuk, Ekin D; Chen, Hua; Zhu, Wenguang; Kaxiras, Efthimios; Zhang, S B; Xu, Xiaohong; Zhang, Zhenyu

    2016-07-29

    The quantum anomalous Hall effect (QAHE) is a fundamental quantum transport phenomenon that manifests as a quantized transverse conductance in response to a longitudinally applied electric field in the absence of an external magnetic field, and it promises to have immense application potential in future dissipationless quantum electronics. Here, we present a novel kinetic pathway to realize the QAHE at high temperatures by n-p codoping of three-dimensional topological insulators. We provide a proof-of-principle numerical demonstration of this approach using vanadium-iodine (V-I) codoped Sb_{2}Te_{3} and demonstrate that, strikingly, even at low concentrations of ∼2%  V and ∼1% I, the system exhibits a quantized Hall conductance, the telltale hallmark of QAHE, at temperatures of at least ∼50  K, which is 3 orders of magnitude higher than the typical temperatures at which it has been realized to date. The underlying physical factor enabling this dramatic improvement is tied to the largely preserved intrinsic band gap of the host system upon compensated n-p codoping. The proposed approach is conceptually general and may shed new light in experimental realization of high-temperature QAHE.

  13. Intrinsic quantum anomalous Hall effect in the kagome lattice Cs2LiMn3F12

    DOE PAGES

    Xu, Gang; Lian, Biao; Zhang, Shou -Cheng

    2015-10-27

    In a kagome lattice, the time reversal symmetry can be broken by a staggered magnetic flux emerging from ferromagnetic ordering and intrinsic spin-orbit coupling, leading to several well-separated nontrivial Chern bands and intrinsic quantum anomalous Hall effect. Based on this idea and ab initio calculations, we propose the realization of the intrinsic quantum anomalous Hall effect in the single layer Cs2Mn3F12 kagome lattice and on the (001) surface of a Cs2LiMn3F12 single crystal by modifying the carrier coverage on it, where the band gap is around 20 meV. Furthermore, a simplified tight binding model based on the in-plane ddσ antibondingmore » states is constructed to understand the topological band structures of the system.« less

  14. Intrinsic Quantum Anomalous Hall Effect in the Kagome Lattice Cs_{2}LiMn_{3}F_{12}.

    PubMed

    Xu, Gang; Lian, Biao; Zhang, Shou-Cheng

    2015-10-30

    In a kagome lattice, the time reversal symmetry can be broken by a staggered magnetic flux emerging from ferromagnetic ordering and intrinsic spin-orbit coupling, leading to several well-separated nontrivial Chern bands and intrinsic quantum anomalous Hall effect. Based on this idea and ab initio calculations, we propose the realization of the intrinsic quantum anomalous Hall effect in the single layer Cs_{2}Mn_{3}F_{12} kagome lattice and on the (001) surface of a Cs_{2}LiMn_{3}F_{12} single crystal by modifying the carrier coverage on it, where the band gap is around 20 meV. Moreover, a simplified tight binding model based on the in-plane ddσ antibonding states is constructed to understand the topological band structures of the system.

  15. Effect of band filling on anomalous Hall conductivity and magneto-crystalline anisotropy in NiFe epitaxial thin films

    SciTech Connect

    Shi, Zhong; Jiang, Hang-Yu; Zhou, Shi-Ming; Hou, Yan-Liang; Ye, Quan-Lin; Su Si, Ming

    2016-01-15

    The anomalous Hall effect (AHE) and magneto-crystalline anisotropy (MCA) are investigated in epitaxial Ni{sub x}Fe{sub 1−x} thin films grown on MgO (001) substrates. The scattering independent term b of anomalous Hall conductivity shows obvious correlation with cubic magneto-crystalline anisotropy K{sub 1}. When nickel content x decreasing, both b and K{sub 1} vary continuously from negative to positive, changing sign at about x = 0.85. Ab initio calculations indicate Ni{sub x}Fe{sub 1−x} has more abundant band structures than pure Ni due to the tuning of valence electrons (band fillings), resulting in the increased b and K{sub 1}. This remarkable correlation between b and K{sub 1} can be attributed to the effect of band filling near the Fermi surface.

  16. Effects of graduated compression stockings on skin temperature after running.

    PubMed

    Priego Quesada, J I; Lucas-Cuevas, A G; Gil-Calvo, M; Giménez, J V; Aparicio, I; Cibrián Ortiz de Anda, R M; Salvador Palmer, R; Llana-Belloch, S; Pérez-Soriano, P

    2015-08-01

    High skin temperatures reduce the thermal gradient between the core and the skin and they can lead to a reduction in performance and increased risk of injury. Graduated compression stockings have become popular among runners in the last years and their use may influence the athlete's thermoregulation. The aim of this study was to investigate the effects of graduated compression stockings on skin temperature during running in a moderate indoor environment. Forty-four runners performed two running tests lasting 30min (10min of warm-up and 20min at 75% of their maximal aerobic speed) with and without graduated compressive stockings. Skin temperature was measured in 12 regions of interest on the lower limb by infrared thermography before and after running. Heart rate and perception of fatigue were assessed during the last minute of the running test. Compression stockings resulted in greater increase of temperature (p=0.002 and ES=2.2, 95% CI [0.11-0.45°C]) not only in the body regions in contact (tibialis anterior, ankle anterior and gastrocnemius) but also in the body regions that were not in contact with the garment (vastus lateralis, abductor and semitendinosus). No differences were observed between conditions in heart rate and perception of fatigue (p>0.05 and ES<0.8). In conclusion, running with graduated compression stockings produces a greater increase of skin temperature without modifying the athlete's heart rate and perception of fatigue.

  17. Sunscreen effects in skin analyzed by photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Dos Anjos, F. H.; Rompe, P. C. B.; Mansanares, A. M.; da Silva, E. C.; Acosta-Avalos, D.; Barja, P. R.

    2005-06-01

    In this work, photoacoustic spectroscopy (PAS) was employed to characterize samples of commercially available sunscreen (SPF15) and the system formed by sunscreen plus skin (topically applied sunscreen). Measurements were performed at 70Hz, in the wavelength range that corresponds to most of the ultraviolet (UV) radiation that reaches Earth. The absorption spectrum of sunscreen was obtained in vitro and in situ., showing that the sunscreen analyzed presents an effective absorption of the UV radiation After that, the PAS technique was used to monitor the absorption kinetics of sunscreen applied to human skin (abdomen) samples, characterizing alterations in the human skin after application of sunscreen. This was done by applying the sunscreen in a skin sample and recording the absorption spectra in regular time intervals, up to 90 minutes after application. Measurements show that light absorption by the system sunscreen plus skin stabilizes between 25 and 45 minutes after sunscreen application. This agrees with the instructions given by the producers about the need of applying the sunscreen at least 30 minutes before sun exposition. The requirement to periodically reapply the sunscreen is confirmed by the progressive decrease in the level of UV absorption as a function of time.

  18. Effects of anomalous permittivity on the microwave heating of zinc oxide

    NASA Astrophysics Data System (ADS)

    Martin, L. P.; Dadon, D.; Rosen, M.; Gershon, D.; Rybakov, K. I.; Birman, A.; Calame, J. P.; Levush, B.; Carmel, Y.; Hutcheon, R.

    1998-01-01

    Highly nonuniform heating has been observed in zinc oxide (ZnO) powder compacts exposed to 2.45 GHz microwaves in oxygen deficient atmospheres such as pure nitrogen or argon. This phenomenon manifests as a localized zone of rapid heating which propagates outward from the sample core, and is documented by real-time surface and core temperature measurements performed during the microwave exposure. Measurements of the complex permittivity, ɛ″, during heating of identical ZnO samples in a conventional furnace and in a nitrogen atmosphere, demonstrated that ɛ″ experiences at least one significant maximum between 200 and 500 °C. Mass spectrometry results indicate that the peaks in ɛ″ correlate well with the rate of desorption of chemisorbed water from the surface of the ZnO powder. It was also noted that the nonuniform heating does not manifest when the microwave exposure is performed in air. Similarly, the anomalous peaks in ɛ″ are almost completely suppressed during heating in air. It is well known that oxygen adsorbs strongly to the surface of ZnO in the temperature range from room temperature to 300 °C, and that this adsorption results in a drastic decrease in the electrical conductivity and, thus, in ɛ″. It is proposed, therefore, that the effect of water desorption upon the complex permittivity may be, in effect, counterbalanced by the adsorption oxygen from the atmosphere. The effect of this behavior may be significant during microwave processing, where nonuniform power absorption can result in extremely localized heating.

  19. Modeling and analysis of cosmetic treatment effects on human skin

    NASA Astrophysics Data System (ADS)

    Lunderstaedt, Reinhart A.; Hopermann, Hermann; Hillemann, Thomas

    2000-10-01

    In view of treatment effects of cosmetics, quality management becomes more and more important. Due to the efficiency reasons it is desirable to quantify these effects and predict them as a function of time. For this, a mathematical model of the skin's surface (epidermis) is needed. Such a model cannot be worked out purely analytically. It can only be derived with the help of measurement data. The signals of interest as output of different measurement devices consist of two parts: noise of high (spatial) frequencies (stochastic signal) and periodic functions (deterministic signal) of low (spatial) frequencies. Both parts can be separated by correlation analysis. The paper introduces in addition to the Fourier Transform (FT) with the Wavelet Transform (WT), a brand new, highly sophisticated method with excellent properties for both modeling the skin's surface as well as evaluating treatment effects. Its main physical advantage is (in comparison to the FT) that local irregularities in the measurement signal (e.g. by scars) remain at their place and are not represented as mean square values as it is the case when applying the FT. The method has just now been installed in industry and will there be used in connection with a new in vivo measurement device for quality control of cosmetic products. As texture parameter for an integral description of the human skin the fractal dimension D is used which is appropriate for classification of different skin regions and treatment effects as well.

  20. Anomalous transmission of an ultrashort ionizing laser pulse through a thin foil.

    PubMed

    Ferrante, G; Zarcone, M; Uryupin, S A

    2003-08-22

    The formation of a highly anisotropic photoelectron velocity distribution as a result of the interaction of a powerful ultrashort laser pulse with a thin foil is found to yield a large skin-layer depth and an anomalous increase of the transmission coefficient. The physical reason for the effect is the influence of the incident wave magnetic field, through the Lorenz force, on the electron kinetics in the skin layer.

  1. Local orbitals approach to the anomalous Hall and Nernst effects in itinerant ferromagnets

    NASA Astrophysics Data System (ADS)

    Středa, Pavel

    2014-07-01

    Linear response of the orbital momentum to the gradient of the chemical potential is used to obtain anomalous Hall conductivity. Transition from the ideal Bloch system for which the conductivity is determined by the Berry phase curvatures to the case of strong disorder for which the conductivity becomes dependent on the relaxation time is analysed. Presented tight-binding model reproduces experimentally observed qualitative features of the anomalous Hall conductivity and the transverse Peltier coefficient in the so called bad-metal and scattering-independent regimes.

  2. The effect of mother-infant skin-to-skin contact on infants' response to the Still Face Task from newborn to three months of age.

    PubMed

    Bigelow, Ann E; Power, Michelle

    2012-04-01

    The effect of mother-infant skin-to-skin contact on infants' developing social expectations for maternal behavior was investigated longitudinally over infants' first 3 months. Infants with and without skin-to-skin contact engaged with their mothers in the Still Face Task at ages 1 week, 1 month, 2 months, and 3 months. Infants with skin-to-skin contact began responding to changes in their mothers' behavior with their affect at 1 month; infants without skin-to-skin contact did so at 2 months. At 3 months, infants with skin-to-skin contact increased their non-distress vocalizations during the still face phase, suggesting social bidding to their mothers. Skin-to-skin contact accelerated infants' social expectations for their mothers' behavior and enhanced infants' awareness of themselves as active agents in social interactions.

  3. Thickness dependence of magnetic anisotropy and intrinsic anomalous Hall effect in epitaxial Co2MnAl film

    NASA Astrophysics Data System (ADS)

    Meng, K. K.; Miao, J.; Xu, X. G.; Zhao, J. H.; Jiang, Y.

    2017-04-01

    We have investigated the thickness dependence of magnetic anisotropy and intrinsic anomalous Hall effect (AHE) in single-crystalline full-Heusler alloy Co2MnAl (CMA) grown by molecular-beam epitaxy on GaAs(001). The magnetic anisotropy is the interplay of uniaxial and the fourfold anisotropy, and the corresponding anisotropy constants have been deduced. Considering the thickness of CMA is small, we ascribe it to the influence from interface stress. The AHE in CMA is found to be well described by a proper scaling. The intrinsic anomalous conductivity is found to be smaller than the calculated one and is thickness dependent, which is ascribed to the influence of chemical ordering by affecting the band structure and Fermi surface.

  4. Beer and beer compounds: physiological effects on skin health.

    PubMed

    Chen, W; Becker, T; Qian, F; Ring, J

    2014-02-01

    Beer is one of the earliest human inventions and globally the most consumed alcoholic beverage in terms of volume. In addition to water, the 'German Beer Purity Law', based on the Bavarian Beer Purity Law from 1516, allows only barley, hops, yeasts and water for beer brewing. The extracts of these ingredients, especially the hops, contain an abundance of polyphenols such as kaempferol, quercetin, tyrosol, ferulic acid, xanthohumol/isoxanthohumol/8-prenylnaringenin, α-bitter acids like humulone and β-bitter acids like lupulone. 8-prenylnaringenin is the most potent phytoestrogen known to date. These compounds have been shown to possess various anti-bacterial, anti-inflammatory, anti-oxidative, anti-angiogenic, anti-melanogenic, anti-osteoporotic and anti-carcinogenic effects. Epidemiological studies on the association between beer drinking and skin disease are limited while direct evidence of beer compounds in clinical application is lacking. Potential uses of these substances in dermatology may include treatment of atopic eczema, contact dermatitis, pigmentary disorders, skin infections, skin ageing, skin cancers and photoprotections, which require an optimization of the biostability and topical delivery of these compounds. Further studies are needed to determine the bioavailability of these compounds and their possible beneficial health effects when taken by moderate beer consumption.

  5. Anomalous Pulsars

    NASA Astrophysics Data System (ADS)

    Malov, I. F.

    Many astrophysicists believe that Anomalous X-Ray Pulsars (AXP), Soft Gamma-Ray Repeaters (SGR), Rotational Radio Transients (RRAT), Compact Central Objects (CCO) and X-Ray Dim Isolated Neutron Stars (XDINS) belong to different classes of anomalous objects with neutron stars as the central bodies inducing all their observable peculiarities. We have shown earlier [1] that AXPs and SGRs could be described by the drift model in the framework of the preposition on usual properties of the central neutron star (rotation periods P 0.01 - 1 sec and, surface magnetic fields B ~ 10^11-10^13 G). Here we shall try to show that some differences of the sources under consideration will be explained by their geometry (particularly, by the angle β between their rotation and magnetic axes). If β <~ 100 (the aligned rotator) the drift waves at the outer layers of the neutron star magnetosphere should play a key role in the observable periodicity. For large values of β (the case of the nearly orthogonal rotator) an accretion from the surrounding medium (for example, from the relic disk) can cause some modulation and transient events in received radiation. Recently Kramer et al. [2] and Camilo et al. [3] have shown that AXPs J1810-197 and 1E 1547.0 - 5408 have both small angles β, that is these sources are nearly aligned rotators, and the drift model should be used for their description. On the other hand, Wang et al. [4] detected IR radiation from the cold disk around the isolated young X-ray pulsar 4U 0142+61. This was the first evidence of the disk-like matter around the neutron star. Probably there is the bimodality of anomalous pulsars. AXPs, SGRs and some radio transients belong to the population of aligned rotators with the angle between the rotation axis and the magnetic moment β < 200. These objects are described by the drift model, and their observed periods are connected with a periodicity of drift waves. Other sources have β ~ 900, and switching on's and switching off

  6. Competing effects of magnetic impurities in the anomalous Hall effect on the surface of a topological insulator

    NASA Astrophysics Data System (ADS)

    Deng, Ming-Xun; Luo, Wei; Deng, W. Y.; Chen, M. N.; Sheng, L.; Xing, D. Y.

    2016-12-01

    We investigate the anomalous Hall effect (AHE) on the surface of a topological insulator induced by a finite concentration of magnetic impurities, and find topologically nontrivial and trivial mechanisms simultaneously contributing to the Hall conductivity. In the topologically nontrivial mechanism, the impurities gap the surface spectrum and result in a half-integer quantized intrinsic Hall conductivity in units e2/h , while in the topologically trivial mechanism, the half-integer quantized plateau is modified by impurity-induced localized states via a gap-filling process. The nonmagnetic charge potential itself, though participating in the gap-filling process, cannot induce the AHE. In the presence of a finite magnetic potential, the charge potential would destroy the symmetric distribution of the Hall conductivity by redistributing the localized levels. More interestingly, the sign of the Hall conductivity is tunable by changing the strength of the charge potential.

  7. Effect of tap-water iontophoresis on sweat gland recruitment, skin temperature and skin blood flow.

    PubMed

    Kolkhorst, Fred W; DiPasquale, Dana M; Buono, Michael J

    2002-02-01

    Our interest was to quantify the role of sweat gland activation on the maintenance of skin temperature during mild exercise in the heat. Seven days of tap-water iontophoresis decreased the number of active sweat glands by 72% which significantly increased forearm skin temperature and blood flow during mild exercise (70 W) in the heat (32 degrees C). Skin temperature of the treated forearm was 0.5 degrees C warmer (P=0.049); skin blood flow in the treated forearm was 13% higher than the control arm (P=0.021). These results illustrate the importance of sweat evaporation on skin temperature and blood flow during exercise.

  8. Metal nanoparticles amplify photodynamic effect on skin cells in vitro

    NASA Astrophysics Data System (ADS)

    Bauer, Brigitte; Chen, Si; Käll, Mikael; Gunnarsson, Linda; Ericson, Marica B.

    2011-03-01

    We report on an investigation aimed to increase the efficiency of photodynamic therapy (PDT) through the influence of localized surface plasmon resonances (LSPR's) in metal nanoparticles. PDT is based on photosensitizers that generate singlet oxygen at the tumour site upon exposure to visible light. Although PDT is a well-established treatment for skin cancer, a major drawback is the low quantum yield for singlet-oxygen production. This motivates the development of novel methods that enhance singlet oxygen generation during treatment. In this context, we study the photodynamic effect on cultured human skin cells in the presence or absence of gold nanoparticles with well established LSPR and field-enhancement properties. The cultured skin cells were exposed to protoporphyrin IX and gold nanoparticles and subsequently illuminated with red light. We investigated the differences in cell viability by tuning different parameters, such as incubation time and light dose. In order to find optimal parameters for specific targeting of tumour cells, we compared normal human epidermal keratinocytes with a human squamous skin cancer cell line. The study indicates significantly enhanced cell death in the presence of nanoparticles and important differences in treatment efficiency between normal and tumour cells. These results are thus promising and clearly motivate further development of nanoparticle enhanced clinical PDT treatment.

  9. Effect of early skin-to-skin contact on breast-feeding.

    PubMed

    Suzuki, S

    2013-10-01

    We examined the effect of early skin-to-skin contact (SSC) on breast-feeding at 1 month after delivery, in Japanese women. We reviewed the obstetric records of healthy nulliparous women with vaginal singleton delivery at 37-41 weeks' gestation, at the Japanese Red Cross Katsushika Maternity Hospital and between 1 February and 30 November 2011, there was a total of 403 women who planned to breast-feed their babies at birth. Of these, 272 women (67.5%) initiated early SSC in the delivery room and 131 women (32.5%) did not initiate early SSC. There were no significant differences in the obstetric characteristics and birth outcomes between the two groups of women with and without initiating early SSC. However, the rate of exclusive breast-feeding at 1 month after delivery in the group of women following early SSC (59.6%, 162/272) was significantly higher than that in the group of women without early SSC (45.8%, 60/131; crude OR 1.74, 95% CI 1.1-2.7, p = 0.009). The current results may support the benefit of early SSC in Japanese women after vaginal delivery.

  10. Evaluation of skin viability effect on ethosome and liposome-mediated psoralen delivery via cell uptake.

    PubMed

    Zhang, Yong-Tai; Shen, Li-Na; Wu, Zhong-Hua; Zhao, Ji-Hui; Feng, Nian-Ping

    2014-10-01

    This study investigated the effect of skin viability on its permeability to psoralen delivered by ethosomes, as compared with liposomes. With decreasing skin viability, the amount of liposome-delivered psoralen that penetrated through the skin increased, whereas skin deposition of psoralen from both ethosomes and liposomes reduced. Psoralen delivery to human-immortalized epidermal cells was more effective using liposomes, whereas delivery to human embryonic skin fibroblast cells was more effective when ethosomes were used. These findings agreed with those of in vivo studies showing that skin psoralen deposition from ethosomes and liposomes first increased and then plateaued overtime, which may indicate gradual saturation of intracellular drug delivery. It also suggested that the reduced deposition of ethosome- or liposome-delivered psoralen in skin with reduced viability may relate to reduced cellular uptake. This work indicated that the effects of skin viability should be taken into account when evaluating nanocarrier-mediated drug skin permeation.

  11. Strong anisotropic anomalous Hall effect and spin Hall effect in the chiral antiferromagnetic compounds Mn3X (X =Ge , Sn, Ga, Ir, Rh, and Pt)

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Sun, Yan; Yang, Hao; Železný, Jakub; Parkin, Stuart P. P.; Felser, Claudia; Yan, Binghai

    2017-02-01

    We have carried out a comprehensive study of the intrinsic anomalous Hall effect and spin Hall effect of several chiral antiferromagnetic compounds Mn3X (X = Ge, Sn, Ga, Ir, Rh and Pt) by ab initio band structure and Berry phase calculations. These studies reveal large and anisotropic values of both the intrinsic anomalous Hall effect and spin Hall effect. The Mn3X materials exhibit a noncollinear antiferromagnetic order which, to avoid geometrical frustration, forms planes of Mn moments that are arranged in a Kagome-type lattice. With respect to these Kagome planes, we find that both the anomalous Hall conductivity (AHC) and the spin Hall conductivity (SHC) are quite anisotropic for any of these materials. Based on our calculations, we propose how to maximize AHC and SHC for different materials. The band structures and corresponding electron filling, that we show are essential to determine the AHC and SHC, are compared for these different compounds. We point out that Mn3Ga shows a large SHC of about 600 (ℏ /e ) (Ωcm) -1 . Our work provides insights into the realization of strong anomalous Hall effects and spin Hall effects in chiral antiferromagnetic materials.

  12. Moisturizing effect of topical cosmetic products applied to dry skin.

    PubMed

    Polaskova, Jana; Pavlackova, Jana; Vltavska, Pavlina; Mokrejs, Pavel; Janis, Rahula

    2013-01-01

    One of the complications of "diabetes mellitus" is termed diabetic foot syndrome, the first symptoms of which include changes in the skin's condition and properties. The skin becomes dehydrated, dry, and prone to excessive formation of the horny layer, its barrier function becoming weakened. This function can be restored by applying suitable cosmetic excipients containing active substances. The aim of this study was to evaluate and compare the effects of commercially available cosmetic products (CPs) designed for the care of diabetic foot, through a group of selected volunteers using noninvasive bioengineering methods. Statistical surveys (p < 0.05) evaluated these CPs as regards to their hydration effect and barrier properties. Special attention was devoted to CPs with the declared content of 10% urea, and that the influence of this preparation's ability to hydrate and maintain epidermal water in the epidermis was confirmed.

  13. Effect of entropy on anomalous transport in electron-temperature-gradient-modes

    SciTech Connect

    Yaqub Khan, M.; Iqbal, J.; Ul Haq, A.

    2014-05-15

    Due to the interconnection of entropy with temperature and density of plasma, it would be interesting to investigate plasma related phenomena with respect to entropy. By employing Braginskii transport equations, it is proved that entropy is proportional to a function of potential and distribution function of entropy is re-defined, ∇S–drift in obtained. New dispersion relation is derived; it is found that the anomalous transport depends on the gradient of the entropy.

  14. Skin effect with arbitrary specularity in Maxwellian plasma

    SciTech Connect

    Latyshev, A. V.; Yushkanov, A. A.

    2010-11-15

    The problem of the skin effect with arbitrary specularity in Maxwellian plasma with specular-diffuse boundary conditions is solved. A new analytical method is developed that makes it possible to obtain a solution up to an arbitrary degree of accuracy. The method is based on the idea of symmetric continuation of not only the electric field, but also electron distribution function. The solution is obtained in a form of von Neumann series.

  15. Skin-sparing effects of neutron beam filtering materials.

    PubMed

    Otte, V A; Almond, P R; Smathers, J B; Attix, F H

    1987-01-01

    The skin-sparing effects of several filtering materials for fast neutron beams were studied under various conditions. A parallel-plate ionization chamber was used for the measurements. The parameters which were studied included field size, distance from filter to ion chamber, filter material, and filter thickness. On the basis of this work, Teflon (polytetrafluoroethylene) was chosen for fabrication of flattening filters and wedges.

  16. Effects of permafrost microorganisms on skin wound reparation.

    PubMed

    Kalenova, L F; Novikova, M A; Subbotin, A M

    2015-02-01

    Local application of ointment with Bacillus spp. strain MG8 (15,000-20,000 living bacterial cells), isolated from permafrost specimens, on the skin wound of about 60 mm(2) stimulated the reparation processes in experimental mice. A possible mechanism stimulating the regeneration of the damaged tissues under the effect of MG8 could be modulation of the immune system reactivity with more rapid switchover to humoral immunity anti-inflammatory mechanisms aimed at de novo synthesis of protein.

  17. Unambiguous separation of the inverse spin Hall and anomalous Nernst effects within a ferromagnetic metal using the spin Seebeck effect

    SciTech Connect

    Wu, Stephen M. Hoffman, Jason; Pearson, John E.; Bhattacharya, Anand

    2014-09-01

    The longitudinal spin Seebeck effect is measured on the ferromagnetic insulator Fe{sub 3}O{sub 4} with the ferromagnetic metal Co{sub 0.2}Fe{sub 0.6}B{sub 0.2} (CoFeB) as the spin detector. By using a non-magnetic spacer material between the two materials (Ti), it is possible to decouple the two ferromagnetic materials and directly observe pure spin flow from Fe{sub 3}O{sub 4} into CoFeB. It is shown that in a single ferromagnetic metal, the inverse spin Hall effect (ISHE) and anomalous Nernst effect (ANE) can occur simultaneously with opposite polarity. Using this and the large difference in the coercive fields between the two magnets, it is possible to unambiguously separate the contributions of the spin Seebeck effect from the ANE and observe the degree to which each effect contributes to the total response. These experiments show conclusively that the ISHE and ANE in CoFeB are separate phenomena with different origins and can coexist in the same material with opposite response to a thermal gradient.

  18. Effects of skin and hydraulic fractures on SVE wells.

    PubMed

    Bradner, Graham C; Murdoch, Lawrence C

    2005-05-01

    Soil vapor extraction (SVE) systems are intended to cause substantial volumes of air to flow through the subsurface with the purpose of removing volatile contaminants. The effectiveness of SVE can be influenced by any effect that changes the specific gas capacity (discharge as a function of vacuum) of a well. Skins of low permeability material enveloping a well bore are widely recognized to affect the performance of wells used to recover water, natural gas, or petroleum, and skin can also significantly diminish the performance of an SVE well. Skins a few mm thick consisting of material whose gas phase permeability is 0.01 of the formation can reduce the specific gas capacity of an SVE well by factors of 2 to 10 or more. Hydraulic fractures created in the vicinities of shallow wells commonly resemble sand-filled layers shaped like flat-lying disks or gently dipping saucers. The contrast between the gas-phase permeability of the sand in the fracture and that of the formation is particularly important, with significant effects requiring the ratio to be greater than approximately 50. Shallow hydraulic fractures filled with several tenths of m3 of sand in formations that are several orders of magnitude less permeable than that of the enveloping formation should increase specific gas capacity by factors of 10 or more. Field tests of the effects of hydraulic fractures on the performance of SVE were conducted by creating four wells intersecting fractures and a suite of control wells created using conventional methods in silty saprolite. Specific gas capacities ranged over more than an order of magnitude for 10 wells completed within a small area (2 m2) and at the same depth. Specific capacities correlate to the drilling method that was used to create the bore for the well: lowest values occurred in wells drilled with a machine auger, slightly better results were obtained using a Shelby tube, and the best results were obtained from conventional wells bored with a hand auger

  19. The Effect of Liquid Gun Propellant (LGP) on Skin.

    DTIC Science & Technology

    1992-02-27

    treated skin. In LGP-treated skin there was a multifocal, superficial, perivascular lymphoplasmacytic dermatitis with moderate perivascular infiltrate ...microscopic lesions observed in the LP-treated skin (Superficial perivascular lymphoplasmacytic dermatitis, edema and increased eosinophils) appeared to...Microscopic lesions in LP treated skin included superficial perivascular lymphoplasmacytic dermatitis, mild edema in the papillary dermis, mild increase

  20. Hysteretic magnetoresistance and unconventional anomalous Hall effect in the frustrated magnet TmB4

    SciTech Connect

    Sunku, Sai Swaroop; Kong, Tai; Ito, Toshimitsu; Canfield, Paul C.; Shastry, B. Sriram; Sengupta, Pinaki; Panagopoulos, Christos

    2016-05-11

    We study TmB4, a frustrated magnet on the Archimedean Shastry-Sutherland lattice, through magnetization and transport experiments. The lack of anisotropy in resistivity shows that TmB4 is an electronically three-dimensional system. The magnetoresistance (MR) is hysteretic at low temperature even though a corresponding hysteresis in magnetization is absent. The Hall resistivity shows unconventional anomalous Hall effect (AHE) and is linear above saturation despite a large MR. In conclusion, we propose that complex structures at magnetic domain walls may be responsible for the hysteretic MR and may also lead to the AHE.

  1. Spin-orbit coupling and perpendicular Zeeman field for fermionic cold atoms: Observation of the intrinsic anomalous Hall effect

    SciTech Connect

    Zhang Chuanwei

    2010-08-15

    We propose a scheme for generating Rashba spin-orbit coupling and a perpendicular Zeeman field simultaneously for cold fermionic atoms in a harmonic trap through the coupling between atoms and laser fields. The realization of Rashba spin-orbit coupling and a perpendicular Zeeman field provides opportunities for exploring many topological phenomena using cold fermionic atoms. We focus on the intrinsic anomalous Hall effect and show that it may be observed through the response of atomic density to a rotation of the harmonic trap.

  2. Effects of Cream Containing Ficus carica L. Fruit Extract on Skin Parameters: In vivo Evaluation

    PubMed Central

    Khan, H.; Akhtar, N.; Ali, A.

    2014-01-01

    This study was aimed to investigate the effects of cream containing Ficus carica L. fruit (Fig) extract on various skin parameters such as skin melanin, erythema, moisture content, trans-epidermal water loss and sebum. For this purpose, formulation with 4% concentrated extract of F. carica fruit and base without extract were developed. Base served as a control. Both base and formulation were applied to the cheeks of human volunteers for 8 weeks to investigate the effects on different skin parameters using non-invasive bioengineering instruments. Formulation decreased the skin melanin, trans-epidermal water loss and skin sebum significantly. Formulation increased the skin hydration significantly and insignificant effects on skin erythema. We concluded that a stable topical cream (w/o emulsion) containing F. carica fruit extract have effects on skin melanin, trans-epidermal loss, hydration values and sebum content and possibly could be used against for hyper pigmentation, acne, freckles and wrinkle. PMID:25593393

  3. Effect on Microbial Growth of a New Skin Protectant Formulation.

    PubMed

    Stoffel, Joseph; Bernatchez, Stéphanie F

    2017-03-01

    Objective: Evaluate the effect of a new investigational skin protectant formulation on the growth of various microorganisms in vitro. Approach: An in vitro laboratory assay with various species of gram-positive bacteria, gram-negative bacteria, and yeast grown on agar plates was used to verify that a new investigational product used for the management of incontinence-associated dermatitis (IAD) does not support microbial growth. Results: The investigational product did not support the growth of all organisms tested for 48 h in these assays. The results demonstrate the barrier properties of this investigational formulation against bacteria and yeast that are relevant to incontinent patients. Innovation: IAD accompanied by skin damage is difficult to manage with currently available products. A new skin protectant that can be applied as a liquid and polymerizes into a breathable film in situ even in the presence of exudate (as shown previously) has been developed and tested to ensure that it does not support microbial growth. Conclusion: This work verifies that this new product does not support microbial growth in vitro using organisms relevant for the intended application.

  4. Effect on Microbial Growth of a New Skin Protectant Formulation

    PubMed Central

    Stoffel, Joseph; Bernatchez, Stéphanie F.

    2017-01-01

    Objective: Evaluate the effect of a new investigational skin protectant formulation on the growth of various microorganisms in vitro. Approach: An in vitro laboratory assay with various species of gram-positive bacteria, gram-negative bacteria, and yeast grown on agar plates was used to verify that a new investigational product used for the management of incontinence-associated dermatitis (IAD) does not support microbial growth. Results: The investigational product did not support the growth of all organisms tested for 48 h in these assays. The results demonstrate the barrier properties of this investigational formulation against bacteria and yeast that are relevant to incontinent patients. Innovation: IAD accompanied by skin damage is difficult to manage with currently available products. A new skin protectant that can be applied as a liquid and polymerizes into a breathable film in situ even in the presence of exudate (as shown previously) has been developed and tested to ensure that it does not support microbial growth. Conclusion: This work verifies that this new product does not support microbial growth in vitro using organisms relevant for the intended application. PMID:28289552

  5. Effect of microplasma irradiation on skin barrier function

    NASA Astrophysics Data System (ADS)

    Shimizu, Kazuo; Tran, Nhat An; Blajan, Marius

    2015-09-01

    This study investigates the feasibility of atmospheric-pressure argon microplasma irradiation (AAMI) to promote drug delivery through skin. Yucatan micropig skin was used as a biological object for evaluation of in vitro percutaneous absorption. The changes in lipids, proteins and water content of the pig stratum corneum (SC) after AAMI were compared to those of a tape stripping test (TST) and plasma jet irradiation (PJI) using attenuated total reflection-Fourier transform infrared spectroscopy analysis. The significant reduction in the methylene stretching modes absorbance resulted in the disturbance in the SC lipids caused by AAMI was observed at 2850 and 2920 cm-1. Moreover, as the result of TST, trans-epidermal water loss (TEWL) after both AAMI and PJI were also increased, that could lead to a decrease of barrier function of SC, and could enhance the transdermal absorption of drugs. Under the conditions of this study, TEWL value of 5 minutes AAMI (35.92 +/- 3.48 g/m2h) was approximately the same as that value of 10 times TST (34.30 +/- 3.54 g/m2h), that makes the effect of these manipulations on the surfaces is considered to be at the same levels. Furthermore, unlike the obtained microscopic observation from PJI, there was no thermal damage observed on the skins after AAMI.

  6. Effects of skin cooling on airway reactivity in asthma.

    PubMed

    Skowronski, M E; Ciufo, R; Nelson, J A; McFadden, E R

    1998-05-01

    1. Environmental contact with cold air is a common cause of respiratory distress in obstructive lung disease, and direct and reflex changes in bronchial calibre are well documented with this stimulus when it is inhaled or contacts the exposed skin respectively. It is now known that skin chilling does not amplify the effects of breathing cold air, but it is not established if this lack of interaction is unique, or applies to other forms of airway constrictors. 2. To provide data on this issue, 10 subjects with atopic asthma underwent methacholine bronchoprovocations with and without chilling of the integument of their heads and thoraces for 30 min. Chilling was accomplished with a specially designed thermal garment. Spirometry as well as core and skin temperatures were serially monitored during all experiments. 3. In the control phase (no cooling), integumental temperatures rose slightly, the forced expiratory volume in 1.0 s (FEV1.0) did not change, and the mean provocative concentration of methacholine required to reduce the FEV1.0 by 20% (PC20 meth) was 0.47 +/- 0.17 mg/ml (2.4 +/- 0.87 mmol/l). In the cold trial, the temperature of the back fell 5.1 +/- 1.7 degrees C to 28.7 +/- 1.8 degrees C (P < 0.01), core temperatures did not change, and airway obstruction developed (delta FEV1.0 = -6.7 +/- 2.1%; P < 0.05). The PC20 meth, however, was unaltered [PC20 meth = 0.45 +/- 0.13 mg/ml (2.3 +/- 0.66 mmol/l); P = 0.85]. 4. These results demonstrate that although skin cooling produces mild airway obstruction in subjects with asthma, it does not change the response to non-specific bronchoconstrictors such as methacholine.

  7. Effects of combined phytochemicals on skin tumorigenesis in SENCAR mice

    PubMed Central

    KOWALCZYK, MAGDALENA C.; JUNCO, JACOB J.; KOWALCZYK, PIOTR; TOLSTYKH, OLGA; HANAUSEK, MARGARET; SLAGA, THOMAS J.; WALASZEK, ZBIGNIEW

    2013-01-01

    The purpose of our study was to determine the effect of the combined action of phytochemicals on the early stages of skin tumorigenesis, i.e. initiation and promotion. We tested calcium D-glucarate (CG) given in the diet, while resveratrol (RES) and ursolic acid (UA) were applied topically. The 7,12-dimethylbenz[a]anthracene (DMBA)-initiated, 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted multistage skin carcinogenesis model in SENCAR mice was used. Mice received one topical dose of DMBA, then after one month, two weekly doses of TPA for 14 weeks until sacrifice. RES or UA were applied 20 min prior to DMBA or TPA treatment and 2% dietary CG was given from 2 weeks prior to 2 weeks after the DMBA dose or continually beginning 2 weeks prior to the first dose of TPA. UA applied alone and in combination with CG during the promotion stage was the only inhibitor of tumor multiplicity and tumor incidence. A number of combinations reduced epidermal proliferation, but only UA and the combination UA+CG applied during promotion significantly reduced epidermal hyperplasia. DMBA/TPA application resulted in significant increases in c-jun and p50, which were reversed by a number of different treatments. DMBA/TPA treatment also strongly increased mRNA levels of inflammation markers COX-2 and IL-6. All anti-promotion treatments caused a marked decrease in COX-2 and IL-6 expression compared to the DMBA/TPA control. These results show that UA is a potent inhibitor of skin tumor promotion and inflammatory signaling and it may be useful in the prevention of skin cancer and other epithelial cancers in humans. PMID:23835587

  8. Effects of combined phytochemicals on skin tumorigenesis in SENCAR mice.

    PubMed

    Kowalczyk, Magdalena C; Junco, Jacob J; Kowalczyk, Piotr; Tolstykh, Olga; Hanausek, Margaret; Slaga, Thomas J; Walaszek, Zbigniew

    2013-09-01

    The purpose of our study was to determine the effect of the combined action of phytochemicals on the early stages of skin tumorigenesis, i.e. initiation and promotion. We tested calcium D-glucarate (CG) given in the diet, while resveratrol (RES) and ursolic acid (UA) were applied topically. The 7,12-dimethylbenz[a]anthracene (DMBA)-initiated, 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted multistage skin carcinogenesis model in SENCAR mice was used. Mice received one topical dose of DMBA, then after one month, two weekly doses of TPA for 14 weeks until sacrifice. RES or UA were applied 20 min prior to DMBA or TPA treatment and 2% dietary CG was given from 2 weeks prior to 2 weeks after the DMBA dose or continually beginning 2 weeks prior to the first dose of TPA. UA applied alone and in combination with CG during the promotion stage was the only inhibitor of tumor multiplicity and tumor incidence. A number of combinations reduced epidermal proliferation, but only UA and the combination UA+CG applied during promotion significantly reduced epidermal hyperplasia. DMBA/TPA application resulted in significant increases in c-jun and p50, which were reversed by a number of different treatments. DMBA/TPA treatment also strongly increased mRNA levels of inflammation markers COX-2 and IL-6. All anti-promotion treatments caused a marked decrease in COX-2 and IL-6 expression compared to the DMBA/TPA control. These results show that UA is a potent inhibitor of skin tumor promotion and inflammatory signaling and it may be useful in the prevention of skin cancer and other epithelial cancers in humans.

  9. The Anomalous Effect of Interface Traps on Generation Current in Lightly Doped Drain nMOSFET's

    NASA Astrophysics Data System (ADS)

    Ma, Xiao-Hua; Gao, Hai-Xia; Cao, Yan-Rong; Chen, Hai-Feng; Hao, Yue

    2010-05-01

    The anomalous phenomenon of generation current IGD in the lightly doped drain (LDD) nMOSFET measured under the drain bias VD-step mode is reported. We propose an assumption of activated (A) and frozen (F) traps for the VD-step mode: The A traps contributes to IGD while the F process can make them lose the roles as generation centers. The A and F regions can form the F-A region. The comparison of the F and A regions decides the role of the F-A region. The experiments confirm the assumption.

  10. Effect of oral intake of choline-stabilized orthosilicic acid on skin, nails and hair in women with photodamaged skin.

    PubMed

    Barel, A; Calomme, M; Timchenko, A; De Paepe, K; Paepe, K De; Demeester, N; Rogiers, V; Clarys, P; Vanden Berghe, D

    2005-10-01

    Chronic exposure of the skin to sunlight causes damage to the underlying connective tissue with a loss of elasticity and firmness. Silicon (Si) was suggested to have an important function in the formation and maintenance of connective tissue. Choline-stabilized orthosilicic acid ("ch-OSA") is a bioavailable form of silicon which was found to increase the hydroxyproline concentration in the dermis of animals. The effect of ch-OSA on skin, nails and hair was investigated in a randomized, double blind, placebo-controlled study. Fifty women with photodamaged facial skin were administered orally during 20 weeks, 10 mg Si/day in the form of ch-OSA pellets (n=25) or a placebo (n=25). Noninvasive methods were used to evaluate skin microrelief (forearm), hydration (forearm) and mechanical anisotropy (forehead). Volunteers evaluated on a virtual analog scale (VAS, "none=0, severe=3") brittleness of hair and nails. The serum Si concentration was significantly higher after a 20-week supplementation in subjects with ch-OSA compared to the placebo group. Skin roughness parameters increased in the placebo group (Rt:+8%; Rm: +11%; Rz: +6%) but decreased in the ch-OSA group (Rt: -16%; Rm: -19%; Rz: -8%). The change in roughness from baseline was significantly different between ch-OSA and placebo groups for Rt and Rm. The difference in longitudinal and lateral shear propagation time increased after 20 weeks in the placebo group but decreased in the ch-OSA group suggesting improvement in isotropy of the skin. VAS scores for nail and hair brittleness were significantly lower after 20 weeks in the ch-OSA group compared to baseline scores. Oral intake of ch-OSA during the 20 weeks results in a significant positive effect on skin surface and skin mechanical properties, and on brittleness of hair and nails.

  11. Laminar separation control effects of shortfin mako shark skin

    NASA Astrophysics Data System (ADS)

    Bradshaw, Michael Thomas

    Shark skin is investigated as a means of laminar flow separation control due to its preferential flow direction as well as the potential for scales to erect and obstruct low-momentum backflow resulting from an adverse pressure gradient acting on the boundary layer. In this study, the effect of the scales on flow reversal is observed in laminar flow conditions. This is achieved by comparing the flow over a pectoral fin from a shortfin mako shark to that over the same fin that is painted to neutralize the effect of the scales on the flow. The effect of the scales on flow reversal is also observed by comparing the flow over a smooth PVC cylinder to that over the same cylinder with samples of mako shark skin affixed to the entire circumference of the cylinder. These samples were taken from the flank region of the shark because the scales at this location have been shown to have the greatest angle of erection compared to the scales on the rest of the shark's body. Scales at this location have an average crown length of 220 microm with a maximum bristling angle of proximately 50 degrees. Because these scales have the highest bristling angle, they have the best potential for separation control. All data was taken using time-resolved Digital Particle Image Velocimetry. The flow over the pectoral fin was analyzed at multiple angles of attack. It was found that the shark skin had the effect of decreasing the size of the separated region over both the pectoral fin and the cylinder as well as decreasing the magnitudes of the reversing flow found in these regions. For all Reynolds numbers tested, drag reduction over 28% was found when applying the sharkskin to the cylinder.

  12. Effect of skin surface lipid on the skin permeation of lidocaine from pressure sensitive adhesives.

    PubMed

    Cheng, Y H; Hosoya, O; Sugibayashi, K; Morimoto, Y

    1994-12-01

    Pressure sensitive adhesives (PSA) tapes containing different concentrations of lidocaine were prepared by a general casting method using styrene-isoprene-styrene block copolymer, and the in vitro skin permeation of lidocaine from each tape was evaluated using diffusion cell and excised hairless rat skin. The skin permeation was proportionally increased by up to 40% lidocaine in the PSA tape and did not change after this concentration. Although the bending point of the steady-state flux via skin concentration curve was found at 40%, saturated concentration or solubility of lidocaine in the tape was estimated to be about 20% by differential scanning calorimetry (DSC) measurement. In addition, the steady-state flux of lidocaine through skin from water or silicone fluid suspension (92 or 120 micrograms/cm2.h, respectively) was very similar to those of 40, 50 and 60% tapes (105, 101 and 112 micrograms/cm2.h, respectively). Decrease in the concentration in tapes during the permeation experiment explained only part of these phenomena. To analyze them further, the drug free PSA tape with or without (control) skin surface lipid was affixed to 50% lidocaine PSA tape for 48 h, and the amount of lidocaine crystal in the layered tapes was measured by DSC. The amount was found to be lower in the lipid-containing tape than in the lipid-free tape, suggesting that skin surface lipid can dissolve lidocaine crystal or solid in PSA tape to decrease its thermodynamic activity. Thus it is important to follow the concentration and thermodynamic activity of lidocaine in PSA tape, skin and the interface between the two layers to exactly assess its skin permeation flux.

  13. Effects of confinement between attractive and repulsive walls on the thermodynamics of an anomalous fluid.

    PubMed

    Leoni, Fabio; Franzese, Giancarlo

    2016-12-01

    We study via molecular-dynamics simulations the thermodynamics of an anomalous fluid confined in a slit pore with one wall structured and attractive and another unstructured and repulsive. We find that the phase diagram of the homogeneous part of the confined fluid is shifted to higher temperatures, densities, and pressures with respect to the bulk, but it can be rescaled on the bulk case. We calculate a moderate increase of mobility of the homogeneous confined fluid that we interpret as a consequence of the layering due to confinement and the collective modes due to long-range correlations. We show that, as in bulk, the confined fluid has structural, diffusion, and density anomalies that order in the waterlike hierarchy, and a liquid-liquid critical point (LLCP). The overall anomalous region moves to higher temperatures, densities, and pressure, and the LLCP displaces to higher temperature compared to bulk. Motivated by experiments, we calculate also the phase diagram not just for the homogeneous part of the confined fluid but for the entire fluid in the pore, and we show that it is shifted toward higher pressures but preserves the thermodynamics, including the LLCP. Because our model has waterlike properties, we argue that in experiments with supercooled water confined in slit pores with a width of >3 nm if hydrophilic and of >1.5 nm if hydrophobic, the existence of the LLCP could be easier to test than in bulk, where it is not directly accessible.

  14. Effects of confinement between attractive and repulsive walls on the thermodynamics of an anomalous fluid

    NASA Astrophysics Data System (ADS)

    Leoni, Fabio; Franzese, Giancarlo

    2016-12-01

    We study via molecular-dynamics simulations the thermodynamics of an anomalous fluid confined in a slit pore with one wall structured and attractive and another unstructured and repulsive. We find that the phase diagram of the homogeneous part of the confined fluid is shifted to higher temperatures, densities, and pressures with respect to the bulk, but it can be rescaled on the bulk case. We calculate a moderate increase of mobility of the homogeneous confined fluid that we interpret as a consequence of the layering due to confinement and the collective modes due to long-range correlations. We show that, as in bulk, the confined fluid has structural, diffusion, and density anomalies that order in the waterlike hierarchy, and a liquid-liquid critical point (LLCP). The overall anomalous region moves to higher temperatures, densities, and pressure, and the LLCP displaces to higher temperature compared to bulk. Motivated by experiments, we calculate also the phase diagram not just for the homogeneous part of the confined fluid but for the entire fluid in the pore, and we show that it is shifted toward higher pressures but preserves the thermodynamics, including the LLCP. Because our model has waterlike properties, we argue that in experiments with supercooled water confined in slit pores with a width of >3 nm if hydrophilic and of >1.5 nm if hydrophobic, the existence of the LLCP could be easier to test than in bulk, where it is not directly accessible.

  15. Effects of disinfectants and detergents on skin irritation.

    PubMed

    Slotosch, Caroline M; Kampf, Günter; Löffler, Harald

    2007-10-01

    We investigated the biological response of regular human skin to alcohol-based disinfectants and detergents in a repetitive test design. Using non-invasive diagnostic tools such as transepidermal water loss, laser-Doppler flowmetry and corneometry, we quantified the irritative effects of a propanol-based hand disinfectant (Sterillium), its propanol mixture (2-propanol 45% w/w and 1-propanol 30% w/w), sodium lauryl sulfate (SLS) 0.5% and distilled water. The substances were applied in a 2-D patch test in a repetitive occlusive test design to the back. Additionally, we performed a wash test on the forearms that was supposed to mimic the skin affection in the normal daily routine of health care workers. In this controlled half-side test design, we included the single application of the hand rub, SLS 0.5% and water as well as a tandem application of the same substances. Patch test and wash test showed similar results. The alcohol-based test preparations showed minimal irritation rather comparable to the application of water. However, the detergent SLS produced stronger barrier disruption, erythema and dryness than the alcohol-based preparations. There was no additional irritation at the combined use of SLS and disinfectants. By contrary, there was even a decrease in barrier disruption and erythema induced by the tandem application of SLS followed by alcohol-based disinfection compared with the use of SLS alone. These findings show a less irritant effect of alcohol-based disinfectants on the skin than detergents. Our study shows that there is no summation of irritating effects of a common detergent and propanol and that the combination of washing and disinfection has a rather protective aspect compared with washing alone.

  16. Protective effect of gelatin and gelatin hydrolysate from salmon skin on UV irradiation-induced photoaging of mice skin

    NASA Astrophysics Data System (ADS)

    Chen, Tiejun; Hou, Hu; Lu, Jiaohan; Zhang, Kai; Li, Bafang

    2016-08-01

    The objective of this study was to investigate the effect of gelatin (SG) isolated from salmon skin and its hydrolysate (SGH) on photoaging skin, and the mechanism responsible for anti-photoaging. The average molecular weights of SG and SGH were 65 kDa and 873 Da, respectively. The amino acid compositions of SG and SGH were similar. Both of them were abundant in hydrophobic amino acids. Twenty-five peptides were identified from SGH. SG and SGH could improve UV irradiation-induced pathological changes of macroscopical tissue texture and skin morphology. Hydroxyproline content is an indicator of matrix collagen content, SG and SGH could inhibit the decrease of hydroxyproline content in photoaging skin in a dose dependent manner. In addition, SG and SGH could alleviate UV irradiation-induced oxidative damages to skin by increasing the activities of total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), increasing the content of glutathione (GSH) and decreasing the content of malonaldehyde (MDA). Moreover, SG and SGH could enhance immune regulation system by increasing the thymus index. Thus, the anti-photoaging mechanisms of SG and SGH were by inhibiting the depletion of antioxidant defense components, involving in the synthesis of collagen and enhancing the function of immune system. Besides, SGH showed a better result in protecting skin from photoaging than SG.

  17. Giant gap quantum spin Hall effect and valley-polarized quantum anomalous Hall effect in cyanided bismuth bilayers

    NASA Astrophysics Data System (ADS)

    Ji, Wei-xiao; Zhang, Chang-wen; Ding, Meng; Zhang, Bao-min; Li, Ping; Li, Feng; Ren, Miao-juan; Wang, Pei-ji; Zhang, Run-wu; Hu, Shu-jun; Yan, Shi-shen

    2016-08-01

    Bismuth (Bi) has attracted a great deal of attention for its strongest spin-orbit coupling (SOC) strength among main group elements. Although quantum anomalous Hall (QAH) state is predicted in half-hydrogenated Bi honeycomb monolayers Bi2H, the experimental results are still missing. Halogen atoms (X = F, Cl and Br) were also frequently used as modifications, but Bi2X films show a frustrating metallic character that masks the QAH effects. Here, first-principle calculations are performed to predict the full-cyanided bismuthene (Bi2(CN)2) as 2D topological insulator supporting quantum spin Hall state with a record large gap up to 1.10 eV, and more importantly, half-cyanogen saturated bismuthene (Bi2(CN)) as a Chern insulator supporting a valley-polarized QAH state, with a Curie temperature to be 164 K, as well as a large gap reaching 0.348 eV which could be further tuned by bi-axial strain and SOC strength. Our findings provide an appropriate and flexible material family candidate for spintronic and valleytronic devices.

  18. Dynamic hysteresis modeling including skin effect using diffusion equation model

    NASA Astrophysics Data System (ADS)

    Hamada, Souad; Louai, Fatima Zohra; Nait-Said, Nasreddine; Benabou, Abdelkader

    2016-07-01

    An improved dynamic hysteresis model is proposed for the prediction of hysteresis loop of electrical steel up to mean frequencies, taking into account the skin effect. In previous works, the analytical solution of the diffusion equation for low frequency (DELF) was coupled with the inverse static Jiles-Atherton (JA) model in order to represent the hysteresis behavior for a lamination. In the present paper, this approach is improved to ensure the reproducibility of measured hysteresis loops at mean frequency. The results of simulation are compared with the experimental ones. The selected results for frequencies 50 Hz, 100 Hz, 200 Hz and 400 Hz are presented and discussed.

  19. [Effect of UV index in the skin exposure].

    PubMed

    Gerbaudo, Mabel; Dionisio de Cabalier, María E

    2010-01-01

    This research was conducted from October 2003 to March 2005, collecting data through the measuring authorized volunteers measuring their photoexposition . It worked with the equipment (Safesun from Optix Tech, Inc.), available for measuring. The radiation impact of solar on the city of Cordoba, was chosen measurements for a clear spot on the terrace of the Observatory Environmental Laprida located at 854, in a position that excedes level approximately 30 meters from Piazza San Martin (centerhistoric city). It had two fixed radiation sensors total solar and ultraviolet A radiation sensor manual ultraviolet calibrated according to the erythemal response of skin measuring human ultraviolet index and the maximum exposure timer ecommended for different skin types (Safesun from Optix Tech, Inc.).The aim of this study was to measure the rate and exposure ultraviolet (UV) to evaluate the erythemal effect on most sensitive areas of the face and neck to noon fotoexposición solar in the four annual seasons, and thus promote extending protection regulations to prevent the effects harmful UV non-ionizing radiation. The analysis of the data, UV index values indicate that from the Winter season is observed to undergo the risk of exposure excessive radiation at noon solar day is measured with high Fall UV index is high in spring and high-very high and with days end in the Summer season daily with UV index very high and extreme. This risk remains in the four annual seasons and according to the criteria of the World Health Organization is need to perform significant work to develop measures, education campaigns and outreach, which tend to diminish the sun exposure, hours with the highest incidence of lightning ultraviolet in the four annual seasons. The global environmental degradation and thus destruction of the ozone layer, has been a direct cause of the increase in ultraviolet radiation on earth, which resulted increased rates of cancer incidence and prevalence skin, within the

  20. Noncontact dipole effects on channel permeation. III. Anomalous proton conductance effects in gramicidin

    PubMed Central

    Phillips, LR; Cole, CD; Hendershot, RJ; Cotten, M; Cross, TA; Busath, DD

    1999-01-01

    Proton transport on water wires, of interest for many problems in membrane biology, is analyzed in side-chain analogs of gramicidin A channels. In symmetrical 0.1 N HCl solutions, fluorination of channel Trp(11), Trp-(13), or Trp(15) side chains is found to inhibit proton transport, and replacement of one or more Trps with Phe enhances proton transport, the opposite of the effects on K(+) transport in lecithin bilayers. The current-voltage relations are superlinear, indicating that some membrane field-dependent process is rate limiting. The interfacial dipole effects are usually assumed to affect the rate of cation translocation across the channel. For proton conductance, however, water reorientation after proton translocation is anticipated to be rate limiting. We propose that the findings reported here are most readily interpreted as the result of dipole-dipole interactions between channel waters and polar side chains or lipid headgroups. In particular, if reorientation of the water column begins with the water nearest the channel exit, this hypothesis explains the negative impact of fluorination and the positive impact of headgroup dipole on proton conductance. PMID:20540928

  1. The effect of pimecrolimus on expression of genes associated with skin barrier dysfunction in atopic dermatitis skin lesions.

    PubMed

    Grzanka, Alicja; Zebracka-Gala, Jadwiga; Rachowska, Regina; Bozek, Andrzej; Kowalska, Małgorzata; Jarzab, Jerzy

    2012-03-01

    The mechanism of action of pimecrolimus (PIM) on atopic lesions is still under consideration. Thus far, we have evidence of its anti-inflammatory and immunomodulatory activity, and recent papers focus on its effect on epidermal barrier function. This study analysed changes in the expression of genes associated with skin barrier dysfunction in atopic dermatitis (AD) skin lesions after 2 weeks of exposure to PIM 1% cream. A real-time quantitative PCR analysis of selected epidermal differentiation complex genes and three alternative pathway keratins was performed in skin biopsies from 11 individuals with AD before and after PIM exposure. The real-time quantitative PCR analysis was compared to non-lesional skin in the same patients. Involucrin, a small proline-rich region (SPRR) 2C gene, and alternative pathway keratin 16 showed significant over-expression in lesional skin followed by significant decrease after PIM therapy. The SPRR1A gene, S100A9, and keratin 6A were also increased; however, the decrease after PIM treatment was not significant. The changes in S100 A2, A7 and A8 followed a similar course with borderline significance. SPRR4 had a significant decrease in expression in lesional versus non-lesional skin, which persisted after PIM treatment. No significant changes were detected in mRNA expression levels of filaggrin and loricrin. Our results suggest that PIM can be effective in restoring the epidermal barrier in patients with AD at least in part by its impact on expression of genes, which are important for the normal barrier function of skin.

  2. Effect of entropy on anomalous transport in ITG-modes of magneto-plasma

    NASA Astrophysics Data System (ADS)

    Yaqub Khan, M.; Qaiser Manzoor, M.; Haq, A. ul; Iqbal, J.

    2017-04-01

    The ideal gas equation and S={{c}v}log ≤ft(P/ρ \\right) (where S is entropy, P is pressure and ρ is the mass density) define the interconnection of entropy with the temperature and density of plasma. Therefore, different phenomena relating to plasma and entropy need to be investigated. By employing the Braginskii transport equations for a nonuniform electron–ion magnetoplasma, two new parameters—the entropy distribution function and the entropy gradient drift—are defined, a new dispersion relation is obtained, and the dependence of anomalous transport on entropy is also proved. Some results, like monotonicity, the entropy principle and the second law of thermodynamics, are proved with a new definition of entropy. This work will open new horizons in fusion processes, not only by controlling entropy in tokamak plasmas—particularly in the pedestal regions of the H-mode and space plasmas—but also in engineering sciences.

  3. Emerging magnetism and anomalous Hall effect in iridate–manganite heterostructures

    PubMed Central

    Nichols, John; Gao, Xiang; Lee, Shinbuhm; Meyer, Tricia L.; Freeland, John W.; Lauter, Valeria; Yi, Di; Liu, Jian; Haskel, Daniel; Petrie, Jonathan R.; Guo, Er-Jia; Herklotz, Andreas; Lee, Dongkyu; Ward, Thomas Z.; Eres, Gyula; Fitzsimmons, Michael R.; Lee, Ho Nyung

    2016-01-01

    Strong Coulomb repulsion and spin–orbit coupling are known to give rise to exotic physical phenomena in transition metal oxides. Initial attempts to investigate systems, where both of these fundamental interactions are comparably strong, such as 3d and 5d complex oxide superlattices, have revealed properties that only slightly differ from the bulk ones of the constituent materials. Here we observe that the interfacial coupling between the 3d antiferromagnetic insulator SrMnO3 and the 5d paramagnetic metal SrIrO3 is enormously strong, yielding an anomalous Hall response as the result of charge transfer driven interfacial ferromagnetism. These findings show that low dimensional spin–orbit entangled 3d–5d interfaces provide an avenue to uncover technologically relevant physical phenomena unattainable in bulk materials. PMID:27596572

  4. Emerging magnetism and anomalous Hall effect in iridate–manganite heterostructures

    DOE PAGES

    Nichols, John; Gao, Xiang; Lee, Shinbuhm; ...

    2016-09-06

    We know strong Coulomb repulsion and spin–orbit coupling to give rise to exotic physical phenomena in transition metal oxides. Initial attempts to investigate systems, where both of these fundamental interactions are comparably strong, such as 3d and 5d complex oxide superlattices, have revealed properties that only slightly differ from the bulk ones of the constituent materials. Furthermore, we observe that the interfacial coupling between the 3d antiferromagnetic insulator SrMnO3 and the 5d paramagnetic metal SrIrO3 is enormously strong, yielding an anomalous Hall response as the result of charge transfer driven interfacial ferromagnetism. Our findings show that low dimensional spin–orbit entangledmore » 3d–5d interfaces provide an avenue to uncover technologically relevant physical phenomena unattainable in bulk materials.« less

  5. Emerging magnetism and anomalous Hall effect in iridate–manganite heterostructures

    SciTech Connect

    Nichols, John; Gao, Xiang; Lee, Shinbuhm; Meyer, Tricia L.; Freeland, John W.; Lauter, Valeria; Yi, Di; Liu, Jian; Haskel, Daniel; Petrie, Jonathan R.; Guo, Er-Jia; Herklotz, Andreas; Lee, Dongkyu; Ward, Thomas Z.; Eres, Gyula; Fitzsimmons, Michael R.; Lee, Ho Nyung

    2016-09-06

    We know strong Coulomb repulsion and spin–orbit coupling to give rise to exotic physical phenomena in transition metal oxides. Initial attempts to investigate systems, where both of these fundamental interactions are comparably strong, such as 3d and 5d complex oxide superlattices, have revealed properties that only slightly differ from the bulk ones of the constituent materials. Furthermore, we observe that the interfacial coupling between the 3d antiferromagnetic insulator SrMnO3 and the 5d paramagnetic metal SrIrO3 is enormously strong, yielding an anomalous Hall response as the result of charge transfer driven interfacial ferromagnetism. Our findings show that low dimensional spin–orbit entangled 3d–5d interfaces provide an avenue to uncover technologically relevant physical phenomena unattainable in bulk materials.

  6. Emerging magnetism and anomalous Hall effect in iridate-manganite heterostructures

    NASA Astrophysics Data System (ADS)

    Nichols, John; Gao, Xiang; Lee, Shinbuhm; Meyer, Tricia L.; Freeland, John W.; Lauter, Valeria; Yi, Di; Liu, Jian; Haskel, Daniel; Petrie, Jonathan R.; Guo, Er-Jia; Herklotz, Andreas; Lee, Dongkyu; Ward, Thomas Z.; Eres, Gyula; Fitzsimmons, Michael R.; Lee, Ho Nyung

    2016-09-01

    Strong Coulomb repulsion and spin-orbit coupling are known to give rise to exotic physical phenomena in transition metal oxides. Initial attempts to investigate systems, where both of these fundamental interactions are comparably strong, such as 3d and 5d complex oxide superlattices, have revealed properties that only slightly differ from the bulk ones of the constituent materials. Here we observe that the interfacial coupling between the 3d antiferromagnetic insulator SrMnO3 and the 5d paramagnetic metal SrIrO3 is enormously strong, yielding an anomalous Hall response as the result of charge transfer driven interfacial ferromagnetism. These findings show that low dimensional spin-orbit entangled 3d-5d interfaces provide an avenue to uncover technologically relevant physical phenomena unattainable in bulk materials.

  7. Emerging magnetism and anomalous Hall effect in iridate-manganite heterostructures.

    PubMed

    Nichols, John; Gao, Xiang; Lee, Shinbuhm; Meyer, Tricia L; Freeland, John W; Lauter, Valeria; Yi, Di; Liu, Jian; Haskel, Daniel; Petrie, Jonathan R; Guo, Er-Jia; Herklotz, Andreas; Lee, Dongkyu; Ward, Thomas Z; Eres, Gyula; Fitzsimmons, Michael R; Lee, Ho Nyung

    2016-09-06

    Strong Coulomb repulsion and spin-orbit coupling are known to give rise to exotic physical phenomena in transition metal oxides. Initial attempts to investigate systems, where both of these fundamental interactions are comparably strong, such as 3d and 5d complex oxide superlattices, have revealed properties that only slightly differ from the bulk ones of the constituent materials. Here we observe that the interfacial coupling between the 3d antiferromagnetic insulator SrMnO3 and the 5d paramagnetic metal SrIrO3 is enormously strong, yielding an anomalous Hall response as the result of charge transfer driven interfacial ferromagnetism. These findings show that low dimensional spin-orbit entangled 3d-5d interfaces provide an avenue to uncover technologically relevant physical phenomena unattainable in bulk materials.

  8. The effect of skin fatty acids on Staphylococcus aureus.

    PubMed

    Neumann, Yvonne; Ohlsen, Knut; Donat, Stefanie; Engelmann, Susanne; Kusch, Harald; Albrecht, Dirk; Cartron, Michael; Hurd, Alexander; Foster, Simon J

    2015-03-01

    Staphylococcus aureus is a commensal of the human nose and skin. Human skin fatty acids, in particular cis-6-hexadecenoic acid (C-6-H), have high antistaphylococcal activity and can inhibit virulence determinant production. Here, we show that sub-MIC levels of C-6-H result in induction of increased resistance. The mechanism(s) of C-6-H activity was investigated by combined transcriptome and proteome analyses. Proteome analysis demonstrated a pleiotropic effect of C-6-H on virulence determinant production. In response to C-6-H, transcriptomics revealed altered expression of over 500 genes, involved in many aspects of virulence and cellular physiology. The expression of toxins (hla, hlb, hlgBC) was reduced, whereas that of host defence evasion components (cap, sspAB, katA) was increased. In particular, members of the SaeRS regulon had highly reduced expression, and the use of specific mutants revealed that the effect on toxin production is likely mediated via SaeRS.

  9. The Photoprotective Effect of S-Methylmethionine Sulfonium in Skin.

    PubMed

    Kim, Won-Serk; Seo, Hyun-Min; Kim, Wang-Kyun; Choi, Joon-Seok; Kim, Ikyon; Sung, Jong-Hyuk

    2015-07-28

    S-Methylmethionine sulfonium (SMMS) was reported to have wound-healing effects; we therefore have investigated the photoprotective effect of SMMS in the present study. SMMS increased the viability of keratinocyte progenitor cells (KPCs) and human dermal fibroblasts (hDFs) following ultraviolet B (UVB) irradiation, and reduced the UVB-induced apoptosis in these cells. SMMS increased the phosphorylation of extracellular signal-regulated kinases (ERK), and the inhibitor of the mitogen-activated protein kinase pathway significantly decreased the SMMS-induced viability of KPCs and hDFs. In addition, SMMS attenuated the UVB-induced reactive oxygen species (ROS) generation in KPCs and hDFs. SMMS induced the collagen synthesis and reduced the matrix metalloproteinase-1 expression in UVB-irradiated hDFs. In animal studies, application of 5% and 10% SMMS before and after UVB-irradiation significantly decreased the UVB-induced erythema index and depletion of Langerhans cells. In summary, SMMS protects KPCs and hDFs from UVB irradiation, and reduces UVB-induced skin erythema and immune suppression. Therefore, SMMS can be used as a cosmetic raw material, and protect skin from UVB.

  10. Effects of calcitriol on random skin flap survival in rats

    PubMed Central

    Zhou, Kai-liang; Zhang, Yi-hui; Lin, Ding-sheng; Tao, Xian-yao; Xu, Hua-zi

    2016-01-01

    Calcitriol, a metabolite of vitamin D, is often used in osteoporosis clinics. However, the material has other bioactivities; for example, it accelerates angiogenesis, has anti-inflammatory properties, and inhibits oxidative stress. We investigated the effects of calcitriol in a random skin flap rat model. “McFarlane flap” models were established in 84 male Sprague Dawley rats, divided into two groups. One group received intraperitoneal injections of calcitriol (2 μg/kg/day) whereas control rats received intraperitoneal injections of saline. The percentage flap survival area and tissue water content were measured 7 days later, which showed that calcitriol improved flap survival area and reduced tissue edema. It also increased the mean vessel density and upregulated levels of VEGF mRNA/protein, both of which promote flap angiogenesis. Moreover, it decreased leukocyte and macrophage infiltration, reduced the inflammatory proteins IL1β and IL6, increased SOD activity, decreased MDA content, and upregulated the level of autophagy. Overall, our results suggest that calcitriol promotes skin flap survival by accelerating angiogenesis, having anti-inflammatory effects, reducing oxidative stress, and promoting autophagy. PMID:26732750

  11. The positive effect of skin transpiration in peach fruit growth.

    PubMed

    Morandi, Brunella; Manfrini, Luigi; Losciale, Pasquale; Zibordi, Marco; Corelli-Grappadelli, Luca

    2010-09-01

    The effect of fruit transpiration on the mechanisms driving peach (Prunus persica (L.) Batsch) daily growth was investigated. In peach, fruit water losses increase during the season and might play a key role in determining fruit growth. Skin transpiration was reduced during the cell expansion stage by enclosing fruit in plastic bags fitted with holes. In the first year, diameter changes of bagged and control fruit were precisely monitored for 15 days, and percentage dry matter and soluble solids content were determined during the experiment and at harvest. In the second year, midday fruit water potential, daily patterns of fruit growth and of vascular and transpiration flows were monitored. Bagging reduced fruit daily growth on some days, and negatively affected both fruit dry matter percentage and soluble solids content. Fruit transpiration rate was reduced during the midday hours, thus increasing midday fruit water potential and lowering xylem inflows. In accordance with the Münch hypothesis on traslocation, these conditions likely decreased the necessary gradient needed for the transport of phloem sap to sink organs, as in the afternoon, bagged fruit showed lower phloem inflows. These data suggest that skin transpiration in peach has a positive effect on fruit growth, as it enhances fruit phloem import.

  12. The Photoprotective Effect of S-Methylmethionine Sulfonium in Skin

    PubMed Central

    Kim, Won-Serk; Seo, Hyun-Min; Kim, Wang-Kyun; Choi, Joon-Seok; Kim, Ikyon; Sung, Jong-Hyuk

    2015-01-01

    S-Methylmethionine sulfonium (SMMS) was reported to have wound-healing effects; we therefore have investigated the photoprotective effect of SMMS in the present study. SMMS increased the viability of keratinocyte progenitor cells (KPCs) and human dermal fibroblasts (hDFs) following ultraviolet B (UVB) irradiation, and reduced the UVB-induced apoptosis in these cells. SMMS increased the phosphorylation of extracellular signal-regulated kinases (ERK), and the inhibitor of the mitogen-activated protein kinase pathway significantly decreased the SMMS-induced viability of KPCs and hDFs. In addition, SMMS attenuated the UVB-induced reactive oxygen species (ROS) generation in KPCs and hDFs. SMMS induced the collagen synthesis and reduced the matrix metalloproteinase-1 expression in UVB-irradiated hDFs. In animal studies, application of 5% and 10% SMMS before and after UVB-irradiation significantly decreased the UVB-induced erythema index and depletion of Langerhans cells. In summary, SMMS protects KPCs and hDFs from UVB irradiation, and reduces UVB-induced skin erythema and immune suppression. Therefore, SMMS can be used as a cosmetic raw material, and protect skin from UVB. PMID:26225962

  13. Skin analysis following dermal exposure to kerosene in rats: the effects of postmortem exposure and fire.

    PubMed

    Hieda, Yoko; Tsujino, Yoshio; Xue, Yuying; Takayama, Koji; Fujihara, Junko; Kimura, Kojiro; Dekio, Satoshi

    2004-02-01

    To evaluate the usefulness of skin analysis for the forensic examination of cases involving postmortem dermal exposure to kerosene and/or fire, an experimental study using rats was performed. Rats received dermal exposure to kerosene before or after death, and the effect of fire was determined by burning an area of exposed skin after death. Kerosene concentrations in skin and blood were determined by gas chromatography-mass spectrometry and microscopic observation was performed for skin samples. No differences were observed in skin kerosene levels between antemortem and postmortem exposure. Kerosene concentrations in mildly burned skin where the stratum corneum (SC) was retained were approximately 84% compared to those in non-burned exposed skin, whereas concentrations in severely burned skin where the SC was almost completely burned off were 28% of non-burned skin. Even in non-exposed control skin 14% of the original kerosene concentrations could be detected, which was considered to be caused by contamination during the experimental protocol combined with kerosene's property of a high affinity for the SC. These results suggest that (1) skin analysis is useful in estimating the type of petroleum product involved in crimes or accidents even for postmortem exposure, (2) whether the SC is retained or not primarily determined the kerosene levels in burned skin, and (3) attention must be paid to evaluate the results obtained from skin samples in the light of the circumstances surrounding the case.

  14. Effect of skin-pass rolling direction on magnetic properties of semiprocessed nonoriented electrical steel sheets

    SciTech Connect

    Kurosaki, Y.; Shimazu, T.; Shiozaki, M.

    1999-09-01

    Effect of skin-pass rolling direction on magnetic properties and directionality in semiprocessed nonoriented electrical steel sheets produced by skin-pass rolling process was studied. Skin-pass rolling direction greatly affects magnetic properties and directionality. By control of skin-pass rolling direction, the value of B{sub 50} in the required directions such as 0{degree}, 90{degree} and circumferential direction can be adjusted and the value of B{sub 50} is higher than that of the usual skin-pass rolling direction of 0{degree}. The textures of the steel sheets developed after batch annealing varied with the skin-pass rolling directions and this result indicates that the residual strain energy by skin-pass rolling varies with skin-pass rolling directions.

  15. Discriminating between Z'-boson effects and effects of anomalous gauge couplings in the double production of W ± bosons at a linear collider

    NASA Astrophysics Data System (ADS)

    Andreev, Vasili V.; Pankov, A. A.

    2013-06-01

    The potential of the International Linear electron-positron Collider (ILC) for seeking, in the annihilation production of W ±-boson pairs, signals induced by new neutral gauge bosons predicted by models belonging to various classes and featuring an extended gauge sector is studied. Limits that will be obtained at ILC for the parameters and masses of Z' bosons are compared with present-day and future data from the Large Hadron Collider (LHC). The possibility of discriminating between the effects of Z-Z' mixing and signals induced by anomalous gauge couplings (AGC) is demonstrated within theoretically motivated trilinear gauge models involving several free anomalous parameters. It is found that the sensitivity of ILC to the effects of Z-Z' mixing in the process e + e - → W + W - and its ability to discriminate between these two new-physics scenarios, Z' and AGC, become substantially higher upon employing polarized initial ( e + e -) and final ( W ±) states.

  16. Anomalous degradation of low-field mobility in short-channel metal-oxide-semiconductor field-effect transistors

    NASA Astrophysics Data System (ADS)

    Natori, Kenji; Iwai, Hiroshi; Kakushima, Kuniyuki

    2015-12-01

    The anomalous degradation of the low-field mobility observed in short-channel metal-oxide-semiconductor field-effect transistors is analyzed by collating various reported data in experiments and simulations. It is inferred that the degradation is not caused by the channel scattering of the carriers. The origin is proposed to be the backscattering of channel carriers on injection into the drain. The expression of the low-field mobility, including the backscattering effect, is derived. The inverse of the low-field mobility is a linear function of the inverse of channel length, the expression of which reproduces that empirically derived by Bidal's group. By fitting the expression to simulated as well as experimental data, we can estimate the value of parameters related to the channel scattering and also to the backscattering from the drain. We find that these values are in reasonable magnitude.

  17. Thermoelectric Signal Enhancement by Reconciling the Spin Seebeck and Anomalous Nernst Effects in Ferromagnet/Non-magnet Multilayers

    PubMed Central

    Lee, Kyeong-Dong; Kim, Dong-Jun; Yeon Lee, Hae; Kim, Seung-Hyun; Lee, Jong-Hyun; Lee, Kyung-Min; Jeong, Jong-Ryul; Lee, Ki-Suk; Song, Hyon-Seok; Sohn, Jeong-Woo; Shin, Sung-Chul; Park, Byong-Guk

    2015-01-01

    The utilization of ferromagnetic (FM) materials in thermoelectric devices allows one to have a simpler structure and/or independent control of electric and thermal conductivities, which may further remove obstacles for this technology to be realized. The thermoelectricity in FM/non-magnet (NM) heterostructures using an optical heating source is studied as a function of NM materials and a number of multilayers. It is observed that the overall thermoelectric signal in those structures which is contributed by spin Seebeck effect and anomalous Nernst effect (ANE) is enhanced by a proper selection of NM materials with a spin Hall angle that matches to the sign of the ANE. Moreover, by an increase of the number of multilayer, the thermoelectric voltage is enlarged further and the device resistance is reduced, simultaneously. The experimental observation of the improvement of thermoelectric properties may pave the way for the realization of magnetic-(or spin-) based thermoelectric devices. PMID:26020492

  18. Thermoelectric Signal Enhancement by Reconciling the Spin Seebeck and Anomalous Nernst Effects in Ferromagnet/Non-magnet Multilayers.

    PubMed

    Lee, Kyeong-Dong; Kim, Dong-Jun; Yeon Lee, Hae; Kim, Seung-Hyun; Lee, Jong-Hyun; Lee, Kyung-Min; Jeong, Jong-Ryul; Lee, Ki-Suk; Song, Hyon-Seok; Sohn, Jeong-Woo; Shin, Sung-Chul; Park, Byong-Guk

    2015-05-28

    The utilization of ferromagnetic (FM) materials in thermoelectric devices allows one to have a simpler structure and/or independent control of electric and thermal conductivities, which may further remove obstacles for this technology to be realized. The thermoelectricity in FM/non-magnet (NM) heterostructures using an optical heating source is studied as a function of NM materials and a number of multilayers. It is observed that the overall thermoelectric signal in those structures which is contributed by spin Seebeck effect and anomalous Nernst effect (ANE) is enhanced by a proper selection of NM materials with a spin Hall angle that matches to the sign of the ANE. Moreover, by an increase of the number of multilayer, the thermoelectric voltage is enlarged further and the device resistance is reduced, simultaneously. The experimental observation of the improvement of thermoelectric properties may pave the way for the realization of magnetic-(or spin-) based thermoelectric devices.

  19. Integer, fractional, and anomalous quantum Hall effects explained with Eyring's rate process theory and free volume concept.

    PubMed

    Hao, Tian

    2017-02-22

    The Hall effects, especially the integer, fractional and anomalous quantum Hall effects, have been addressed using Eyring's rate process theory and free volume concept. The basic assumptions are that the conduction process is a common rate controlled "reaction" process that can be described with Eyring's absolute rate process theory; the mobility of electrons should be dependent on the free volume available for conduction electrons. The obtained Hall conductivity is clearly quantized as with prefactors related to both the magnetic flux quantum number and the magnetic quantum number via the azimuthal quantum number, with and without an externally applied magnetic field. This article focuses on two dimensional (2D) systems, but the approaches developed in this article can be extended to 3D systems.

  20. Metallic transport and large anomalous Hall effect at room temperature in ferrimagnetic Mn{sub 4}N epitaxial thin film

    SciTech Connect

    Shen, Xi; Shigematsu, Kei; Chikamatsu, Akira Fukumura, Tomoteru; Hirose, Yasushi; Hasegawa, Tetsuya

    2014-08-18

    We report the electrical transport properties of ferrimagnetic Mn{sub 4}N (001) epitaxial thin films grown by pulsed laser deposition on MgO (001) substrates. The Mn{sub 4}N thin films were tetragonally distorted with a ratio of out-of-plane to in-plane lattice constants of 0.987 and showed perpendicular magnetic anisotropy with an effective magnetic anisotropy constant of 0.16 MJ/m{sup 3}, which is comparable with that of a recently reported molecular-beam-epitaxy-grown film. The thin films exhibited metallic transport with a room temperature resistivity of 125 μΩ cm in addition to a large anomalous Hall effect with a Hall angle tangent of 0.023.

  1. Excitation wavelength dependence of the anomalous circular photogalvanic effect in undoped InGaAs/AlGaAs quantum wells

    NASA Astrophysics Data System (ADS)

    Zhu, L. P.; Liu, Y.; Jiang, C. Y.; Qin, X. D.; Li, Y.; Gao, H. S.; Chen, Y. H.

    2014-02-01

    The excitation wavelength dependence of the anomalous circular photogalvanic effect (ACPGE) current arising from the reciprocal spin Hall effect (RSHE) in undoped InGaAs/AlGaAs quantum wells is measured under normal incidence of circularly polarized light at room temperature. We found that the spot location with the maximum ACPGE current is wavelength independent. And the normalized ACPGE current decreases at smaller wavelengths, which can be attributed to the sharp decrease of the spin relaxation time (τs) and the hot electron relaxation time (τ1) at smaller wavelengths. The study of the excitation wavelength dependence of ACPGE current is a good supplement to the in-depth investigation of RSHE.

  2. Metallic transport and large anomalous Hall effect at room temperature in ferrimagnetic Mn4N epitaxial thin film

    NASA Astrophysics Data System (ADS)

    Shen, Xi; Chikamatsu, Akira; Shigematsu, Kei; Hirose, Yasushi; Fukumura, Tomoteru; Hasegawa, Tetsuya

    2014-08-01

    We report the electrical transport properties of ferrimagnetic Mn4N (001) epitaxial thin films grown by pulsed laser deposition on MgO (001) substrates. The Mn4N thin films were tetragonally distorted with a ratio of out-of-plane to in-plane lattice constants of 0.987 and showed perpendicular magnetic anisotropy with an effective magnetic anisotropy constant of 0.16 MJ/m3, which is comparable with that of a recently reported molecular-beam-epitaxy-grown film. The thin films exhibited metallic transport with a room temperature resistivity of 125 μΩ cm in addition to a large anomalous Hall effect with a Hall angle tangent of 0.023.

  3. Therapeutic effect of nerve growth factor on cerebral infarction in dogs using the hemisphere anomalous volume ratio of diffusion-weighted magnetic resonance imaging.

    PubMed

    Wang, Yong; Zhang, Hui; Wang, Zhe; Geng, Zuojun; Liu, Huaijun; Yang, Haiqing; Song, Peng; Liu, Qing

    2012-08-25

    A model of focal cerebral ischemic infarction was established in dogs through middle cerebral artery occlusion of the right side. Thirty minutes after occlusion, models were injected with nerve growth factor adjacent to the infarct locus. The therapeutic effect of nerve growth factor against cerebral infarction was assessed using the hemisphere anomalous volume ratio, a quantitative index of diffusion-weighted MRI. At 6 hours, 24 hours, 7 days and 3 months after modeling, the hemisphere anomalous volume ratio was significantly reduced after treatment with nerve growth factor. Hematoxylin-eosin staining, immunohistochemistry, electron microscopy and neurological function scores showed that infarct defects were slightly reduced and neurological function significantly improved after nerve growth factor treatment. This result was consistent with diffusion-weighted MRI measurements. Experimental findings indicate that nerve growth factor can protect against cerebral infarction, and that the hemisphere anomalous volume ratio of diffusion-weighted MRI can be used to evaluate the therapeutic effect.

  4. Therapeutic effect of nerve growth factor on cerebral infarction in dogs using the hemisphere anomalous volume ratio of diffusion-weighted magnetic resonance imaging★

    PubMed Central

    Wang, Yong; Zhang, Hui; Wang, Zhe; Geng, Zuojun; Liu, Huaijun; Yang, Haiqing; Song, Peng; Liu, Qing

    2012-01-01

    A model of focal cerebral ischemic infarction was established in dogs through middle cerebral artery occlusion of the right side. Thirty minutes after occlusion, models were injected with nerve growth factor adjacent to the infarct locus. The therapeutic effect of nerve growth factor against cerebral infarction was assessed using the hemisphere anomalous volume ratio, a quantitative index of diffusion-weighted MRI. At 6 hours, 24 hours, 7 days and 3 months after modeling, the hemisphere anomalous volume ratio was significantly reduced after treatment with nerve growth factor. Hematoxylin-eosin staining, immunohistochemistry, electron microscopy and neurological function scores showed that infarct defects were slightly reduced and neurological function significantly improved after nerve growth factor treatment. This result was consistent with diffusion-weighted MRI measurements. Experimental findings indicate that nerve growth factor can protect against cerebral infarction, and that the hemisphere anomalous volume ratio of diffusion-weighted MRI can be used to evaluate the therapeutic effect. PMID:25624813

  5. Effects of erythropoietin in skin wound healing are dose related.

    PubMed

    Sorg, Heiko; Krueger, Christian; Schulz, Torsten; Menger, Michael D; Schmitz, Frank; Vollmar, Brigitte

    2009-09-01

    The hematopoietic growth factor erythropoietin (EPO) attracts attention due to its all-tissue-protective pleiotropic properties. We studied the effect of EPO on dermal regeneration using intravital microscopy in a model of full dermal thickness wounds in the skin-fold chamber of hairless mice. Animals received repetitive low doses or high doses of EPO (RLD-EPO or RHD-EPO) or a single high dose of EPO (SHD-EPO). SHD-EPO accelerated wound epithelialization, reduced wound cellularity, and induced maturation of newly formed microvascular networks. In contrast, RHD-EPO impaired the healing process, as indicated by delayed epithelialization, high wound cellularity, and lack of maturation of microvascular networks. Also, RHD-EPO caused an excessive erythrocyte mass and rheological malfunction, further deteriorating vessel and tissue maturation. Moreover, RHD-EPO altered fibroblast and keratinocyte migration in vitro, while both cell types exposed to RLD-EPO, and, in particular, to SHD-EPO showed accelerated wound scratch closure. In summary, our data show that a single application of a high dose of EPO accelerates and improves skin wound healing.

  6. IMMUNOMODULATORY EFFECTS OF VITAMIN D ON SKIN INFLAMMATION.

    PubMed

    Toniato, E; Spinas, E; Saggini, A; Kritas, S K; Caraffa, A; Antinolfi, P; Saggini, R; Pandolfi, F; Conti, P

    2015-01-01

    Vitamin D has a major role in calcium absorption and maintenance of healthy bones. Vitamin D is also involved in cancer, cardiovascular system, allergic diseases, immune regulation and immune disor¬ders. Irradiation of food as well as animals produces vitamin D and more than 90% of previtamin D3 synthesis in the skin occurs in the epidermis. Vitamin D receptor has been found in many cells including T and B lymphocytes, macrophages, mast cells, NK cells and Tregs, and it selectively binds with high affinity to its ligand. Vitamin D binds its receptor VDR, resulting in transcription of a number of genes playing a role in inhibition of MAPK. Its effect may be also mediated by the direct activation of PKC. Vitamin D has the ability to suppress inflammatory cytokines such as TNF, IL-1, IFN-gamma and IL-2; while it increases the generation of anti-inflammatory cytokines IL-4 and IL-10. In B cells, vitamin D3 have also been shown to suppress IgE antibody class switch partly through the inhibition of NF-kB. Here we discuss the relationship between vitamin D, immunity and skin disorders.

  7. Effect of olive and sunflower seed oil on the adult skin barrier: implications for neonatal skin care.

    PubMed

    Danby, Simon G; AlEnezi, Tareq; Sultan, Amani; Lavender, Tina; Chittock, John; Brown, Kirsty; Cork, Michael J

    2013-01-01

    Natural oils are advocated and used throughout the world as part of neonatal skin care, but there is an absence of evidence to support this practice. The goal of the current study was to ascertain the effect of olive oil and sunflower seed oil on the biophysical properties of the skin. Nineteen adult volunteers with and without a history of atopic dermatitis were recruited into two randomized forearm-controlled mechanistic studies. The first cohort applied six drops of olive oil to one forearm twice daily for 5 weeks. The second cohort applied six drops of olive oil to one forearm and six drops of sunflower seed oil to the other twice daily for 4 weeks. The effect of the treatments was evaluated by determining stratum corneum integrity and cohesion, intercorneocyte cohesion, moisturization, skin-surface pH, and erythema. Topical application of olive oil for 4 weeks caused a significant reduction in stratum corneum integrity and induced mild erythema in volunteers with and without a history of atopic dermatitis. Sunflower seed oil preserved stratum corneum integrity, did not cause erythema, and improved hydration in the same volunteers. In contrast to sunflower seed oil, topical treatment with olive oil significantly damages the skin barrier, and therefore has the potential to promote the development of, and exacerbate existing, atopic dermatitis. The use of olive oil for the treatment of dry skin and infant massage should therefore be discouraged. These findings challenge the unfounded belief that all natural oils are beneficial for the skin and highlight the need for further research.

  8. Effects of Father-Neonate Skin-to-Skin Contact on Attachment: A Randomized Controlled Trial

    PubMed Central

    Chen, Er-Mei; Liu, Chieh-Yu

    2017-01-01

    This study examines how skin-to-skin contact between father and newborn affects the attachment relationship. A randomized controlled trial was conducted at a regional teaching hospital and a maternity clinic in northern Taiwan. The study recruited 83 first-time fathers aged 20 years or older. By block randomization, participants were allocated to an experimental (n = 41) or a control (n = 42) group. With the exception of skin-to-skin contact (SSC), participants from each group received the same standard care. Both groups also received an Early Childcare for Fathers nursing pamphlet. During the first three days postpartum, the intervention group members were provided a daily SSC intervention with their respective infants. Each intervention session lasted at least 15 minutes in length. The outcome measure was the Father-Child Attachment Scale (FCAS). After adjusting for demographic data, the changes to the mean FCAS were found to be significantly higher in the intervention group than in the control group. We recommend that nurses and midwives use instructional leaflets and demonstrations during postpartum hospitalization, encouraging new fathers to take an active role in caring for their newborn in order to enhance father-neonate interactions and establish parental confidence. This trial is registered with clinical trial registration number NCT02886767. PMID:28194281

  9. Calculations of the neutron skin and its effect in atomic parity violation

    SciTech Connect

    Brown, B. A.; Derevianko, A.; Flambaum, V. V.

    2009-03-15

    We perform calculations for the neutron skin of nuclei and its contribution to atomic parity nonconservation (PNC) in many isotopes of Cs, Ba, Sm, Dy, Yb, Tl, Pb, Bi, Fr, and Ra. Three problems are addressed: (i) neutron-skin-induced errors to single-isotope PNC, (ii) the possibility of measuring neutron skin using atomic PNC, and (iii) neutron-skin-induced errors for ratios of PNC effects in different isotopes. In the latter case the correlations in the neutron skin values for different isotopes lead to cancellations of the errors; this makes the isotopic ratio method a competitive tool in a search for new physics beyond the standard model.

  10. Quantized spin waves in single Co/Pt dots detected by anomalous Hall effect based ferromagnetic resonance

    SciTech Connect

    Kikuchi, N. Furuta, M.; Okamoto, S.; Kitakami, O.; Shimatsu, T.

    2014-12-15

    Anomalous Hall effect (AHE) based ferromagnetic resonance (FMR) measurements were carried out on perpendicularly magnetized Co/Pt multilayer single dots of 0.4–3 μm in diameter. The resonance behavior was measured by detecting the decrease of perpendicular magnetization component due to magnetization precession. Resonance behavior was observed as a clear decrease of Hall voltages, and the obtained resonance fields were consistent with the results of vector-network-analyzer FMR. Spin-waves with cylindrical symmetry became significant by decreasing the dot diameter, and quantized multiple resonances were observed in the dot of 0.4 μm in diameter. The AHE based FMR proposed here is a powerful method to approach magnetization dynamics including spin waves and non-linear behavior excited in a finite nanostructure.

  11. Quantized spin waves in single Co/Pt dots detected by anomalous Hall effect based ferromagnetic resonance

    NASA Astrophysics Data System (ADS)

    Kikuchi, N.; Furuta, M.; Okamoto, S.; Kitakami, O.; Shimatsu, T.

    2014-12-01

    Anomalous Hall effect (AHE) based ferromagnetic resonance (FMR) measurements were carried out on perpendicularly magnetized Co/Pt multilayer single dots of 0.4-3 μm in diameter. The resonance behavior was measured by detecting the decrease of perpendicular magnetization component due to magnetization precession. Resonance behavior was observed as a clear decrease of Hall voltages, and the obtained resonance fields were consistent with the results of vector-network-analyzer FMR. Spin-waves with cylindrical symmetry became significant by decreasing the dot diameter, and quantized multiple resonances were observed in the dot of 0.4 μm in diameter. The AHE based FMR proposed here is a powerful method to approach magnetization dynamics including spin waves and non-linear behavior excited in a finite nanostructure.

  12. High-temperature quantum anomalous Hall effect in honeycomb bilayer consisting of Au atoms and single-vacancy graphene

    PubMed Central

    Han, Yan; Wan, Jian-Guo; Ge, Gui-Xian; Song, Feng-Qi; Wang, Guang-Hou

    2015-01-01

    The quantum anomalous Hall effect (QAHE) is predicted to be realized at high temperature in a honeycomb bilayer consisting of Au atoms and single-vacancy graphene (Au2-SVG) based on the first-principles calculations. We demonstrate that the ferromagnetic state in the Au2-SVG can be maintained up to 380 K. The combination of spatial inversion symmetry and the strong SOC introduced by the Au atoms causes a topologically nontrivial band gap as large as 36 meV and a QAHE state with Chern number C = −2. The analysis of the binding energy proved that the honeycomb bilayer is stable and feasible to be fabricated in experiment. The QAHEs in Ta2-SVG and other TM2-SVGs are also discussed. PMID:26574924

  13. Micro-instabilities and anomalous transport effects in collisionless guide field reconnection

    NASA Astrophysics Data System (ADS)

    Munoz Sepulveda, Patricio Alejandro; Büchner, Jörg; Kilian, Patrick

    2016-07-01

    It is often the case that magnetic reconnection takes place in collisionless plasmas with a current aligned guide magnetic field, such as in the Solar corona. The general characteristics of this process have been exhaustively analyzed with theory and numerical simulations, under different approximations, since some time ago. However, some consequences and properties of the secondary instabilities arising spontaneously -other than tearing instability-, and their dependence on the guide field strength, have not been completely understood yet. For this sake, we use the results of fully kinetic 2D PIC numerical simulations of guide field reconnection. By using a mean field approach for the Generalized Ohm's law that explains the balance of the reconnected electric field, we find that some of the cross-streaming and gradient driven instabilities -in the guide field case- produce an additional anomalous transport term. The latter can be interpreted as a result of the enhanced correlated electromagnetic fluctuations, leading to a slow down of the current carriers and kinetic scale turbulence. We characterize these processes on dependence on the guide field strength, and explore the causal relation with the source of free energy driving the mentioned instabilities. Finally, we show the main consequences that a fully 3D approach have on all those phenomena in contrast to the reduced 2D description.

  14. Vehicle effects on in vitro skin permeation of thiocolchicoside.

    PubMed

    Bonina, F; Puglia, C; Trombetta, D; Dragani, M C; Gentile, M M; Clavenna, G

    2002-11-01

    Thiocolchicoside, a semi-synthetic derivative of colchicoside, is used in topical formulations for its anti-inflammatory and muscle-relaxant properties. The objective of this study was to evaluate the effect of a (propylene glycol diperlagonate) DPPG and (propylene glycol) PG mixture present in an innovative foam formulation (Miotens) on the flux of thiocolchicoside through excised human skin. Furthermore, the in vitro permeation behaviour of this new formulation (Miotens foam) was compared to another commercial product (Muscoril ointment) and to a control gel formulation (thiogel), both enhancer free. The best permeation profile was obtained from the foam formulation (Miotens) which was able to increase the thiocolchicoside flux about three fold compared to control formulation (thiogel) and about two fold compared to the commercial formulation Muscoril ointment.

  15. Nonstochastic effects of different energy beta emitters on pig skin.

    PubMed

    Peel, D M; Hopewell, J W; Wells, J; Charles, M W

    1984-08-01

    Circular areas of pig skin from 1- to 40-mm diameter were irradiated with beta emitters of high, medium, and low energies, 90Sr, 170Tm, and 147Pm, respectively. The study provides information for radiological protection problems of localized skin exposures. During the first 16 weeks after irradiation 90Sr produced a first reaction due to epithelial cell death followed by a second reaction attributable to damage to the dermal blood vessels. 170Tm and 147Pm produced the epithelial reaction only. The epithelial dose response varied as a function of beta energy. The doses required to produce moist desquamation in 50% of 15- to 22.5-mm fields (ED50) were 30-45 Gy from 90Sr, approximately 80 Gy from 170Tm, and approximately 500 Gy from 147Pm. A model involving different methods of epithelial repopulation is proposed to explain this finding. An area effect was observed in the epithelial response to 90Sr irradiation. The ED50 for moist desquamation ranged from approximately 25 Gy for a 40-mm source to approximately 450 Gy for a 1-mm source. The 5-, 9-, and 19-mm 170Tm sources all produced an ED50 of approximately 80 Gy, while the value for the 2-mm source was approximately 250 Gy. It is also suggested that the area effects could be explained by different modes of epithelial repopulation after irradiation. After high energy beta irradiation repopulation would be mainly from the field periphery, while after lower energy irradiation repopulation from hair follicle epithelium would predominate.

  16. Temporal effects in porcine skin following bromine vapor exposure.

    PubMed

    Price, Jennifer A; Rogers, James V; Wendling, Morgan Q S; Plahovinsak, Jennifer L; Perry, Mark R; Reid, Frances M; Kiser, Robyn C; Graham, John S

    2011-09-01

    Bromine is an industrial chemical that causes severe cutaneous burns. When selecting or developing effective treatments for bromine burns, it is important to understand the molecular mechanisms of tissue damage and wound healing. This study investigated the effect of cutaneous bromine vapor exposure on gene expression using a weanling swine burn model by microarray analysis. Ventral abdominal sites were exposed to a mean calculated bromine vapor concentration of 0.51 g/L for 7 or 17 min. At 6 h, 48 h, and 7 days post-exposure, total RNA from skin samples was isolated, processed, and analyzed with Affymetrix GeneChip® Porcine Genome Arrays (N = 3 per experimental group). Differences in gene expression were observed with respect to exposure duration and sampling time. Ingenuity Pathways Analysis (IPA) revealed four common biological functions (cancer, cellular movement, cell-to-cell signaling and interaction, and tissue development) among the top ten functions of each experimental group, while canonical pathway analysis revealed 9 genes (ARG2, CCR1, HMOX1, ATF2, IL-8, TIMP1, ESR1, HSPAIL, and SELE) that were commonly shared among four significantly altered signaling pathways. Among these, the transcripts encoding HMOX1 and ESR1 were identified using IPA as common potential therapeutic targets for Phase II/III clinical trial or FDA-approved drugs. The present study describes the transcriptional responses to cutaneous bromine vapor exposure identifying molecular networks and genes that could serve as targets for developing therapeutics for bromine-induced skin injury.

  17. Development and validation of a tokamak skin effect transformer model

    NASA Astrophysics Data System (ADS)

    Romero, J. A.; Moret, J.-M.; Coda, S.; Felici, F.; Garrido, I.

    2012-02-01

    A lumped parameter, state space model for a tokamak transformer including the slow flux penetration in the plasma (skin effect transformer model) is presented. The model does not require detailed or explicit information about plasma profiles or geometry. Instead, this information is lumped in system variables, parameters and inputs. The model has an exact mathematical structure built from energy and flux conservation theorems, predicting the evolution and non-linear interaction of plasma current and internal inductance as functions of the primary coil currents, plasma resistance, non-inductive current drive and the loop voltage at a specific location inside the plasma (equilibrium loop voltage). Loop voltage profile in the plasma is substituted by a three-point discretization, and ordinary differential equations are used to predict the equilibrium loop voltage as a function of the boundary and resistive loop voltages. This provides a model for equilibrium loop voltage evolution, which is reminiscent of the skin effect. The order and parameters of this differential equation are determined empirically using system identification techniques. Fast plasma current modulation experiments with random binary signals have been conducted in the TCV tokamak to generate the required data for the analysis. Plasma current was modulated under ohmic conditions between 200 and 300 kA with 30 ms rise time, several times faster than its time constant L/R ≈ 200 ms. A second-order linear differential equation for equilibrium loop voltage is sufficient to describe the plasma current and internal inductance modulation with 70% and 38% fit parameters, respectively. The model explains the most salient features of the plasma current transients, such as the inverse correlation between plasma current ramp rates and internal inductance changes, without requiring detailed or explicit information about resistivity profiles. This proves that a lumped parameter modelling approach can be used to

  18. Effect of intense THz pulses on expression of genes associated with skin cancer and inflammatory skin conditions

    NASA Astrophysics Data System (ADS)

    Titova, Lyubov V.; Ayesheshim, Ayesheshim K.; Purschke, David; Golubov, Andrey; Rodriguez-Juarez, Rocio; Woycicki, Rafal; Hegmann, Frank A.; Kovalchuk, Olga

    2014-03-01

    The growing experimental evidence suggests that broadband, picosecond-duration THz pulses may influence biological systems and functions. While the mechanisms by which THz pulse-induced biological effects are not yet known, experiments using in vitro cell cultures, tissue models, as well as recent in vivo studies have demonstrated that THz pulses can elicit cellular and molecular changes in exposed cells and tissues in the absence of thermal effects. Recently, we demonstrated that intense, picosecond THz pulses induce phosphorylation of H2AX, indicative of DNA damage, and at the same time activate DNA damage response in human skin tissues. We also find that intense THz pulses have a profound impact on global gene expression in human skin. Many of the affected genes have important functions in epidermal differentiation and have been implicated in skin cancer and inflammatory skin conditions. The observed THzinduced changes in expression of these genes are in many cases opposite to disease-related changes, suggesting possible therapeutic applications of intense THz pulses.

  19. The effect of sunscreen on skin elastase activity induced by ultraviolet-A irradiation.

    PubMed

    Tsukahara, Kazue; Moriwaki, Shigeru; Hotta, Mitsuyuki; Fujimura, Tsutomu; Sugiyama-Nakagiri, Yoriko; Sugawara, Satoshi; Kitahara, Takashi; Takema, Yoshinori

    2005-12-01

    It has been reported that application of sunscreens prevents the photoaging of skin in animal models and in humans. We irradiated the dorsal skin of hairless mice with ultraviolet-A (UVA), and investigated the effects of sunscreens on skin elastase activity and on skin properties. Six-week-old female HR/ICR hairless mice were used in these experiments. After being treated with either a UVA sunscreen (also containing ultraviolet-B (UVB) sunscreen to eliminate any slight UVB in the UVA lamps; Protection Factor of UVA (PFA)=6, Sun Protection Factor (SPF)=20) or a vehicle, the dorsal skins of mice were irradiated with the UVA lamps at 22.3 J/cm(2)/d, 5 times a week. At the end of 15 weeks skin properties were evaluated and elastase activities were measured. In the vehicle control group, UVA irradiation increased the brightness and yellowing of the skin, decreased the water content of the stratum corneum, increased skin thickness, decreased skin elasticity, increased skin elastase activity, and decreased the ability of the skin to recover in a pinch test, as compared to an unirradiated group. All these differences were statistically significant. In the UVA sunscreen group, both the UVA induced skin damage and the increase in skin elastase activity were significantly inhibited, as compared to the vehicle group. However, as compared to the unirradiated group, skin elastase activity was significantly increased and immediate extensibility of skin (Ue) was significantly decreased, thereby indicating that the UVA sunscreen did not prevent photoaging to the same level as the unirradiated group. These results suggest the partial efficacy of the topical photoprotection from UVA by the sunscreen in inhibiting elastase activation, and also suggest the possibility of reducing photoaging.

  20. Managing Chemotherapy Side Effects: Skin and Nail Changes

    MedlinePlus

    ... better.” Let your doctor or nurse know if: l Your skin is itchy, dry, red, or hurts l Your nails are dark, yellow, or cracked For ... Be careful what you put on your skin. l Use only mild soaps that are gentle on ...

  1. Antioxidant and Anti-inflammatory Effects of Peanut Skin Extracts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peanut skins are regarded as a low economic value by-product of the peanut industry; however, they contain high levels of bioactive compounds including catechins and procyanidins, which are known for their health-promoting properties. The in vitro antioxidant activity of peanut skin extracts (PSE) ...

  2. Effect of seasonal and geographical differences on skin and effect of treatment with an osmoprotectant: Sorbitol.

    PubMed

    Muizzuddin, Neelam; Ingrassia, Michael; Marenus, Kenneth D; Maes, Daniel H; Mammone, Thomas

    2013-01-01

    Human skin maintains an optimal permeability barrier function in a terrestrial environment that varies considerably in humidity. Cells cultured under hyperosmotic stress accumulate osmolytes including sorbitol. Epidermal keratinocytes experience similar high osmolality under dry environmental conditions because of increased transepidermal water loss (TEWL) and concomitant drying of the skin. This study was designed to determine if epidermal keratinocytes, in vitro, could be protected from high osmotic stress, with the exogenous addition of sorbitol. In addition, we evaluated the effect of a formulation containing topical sorbitol on skin barrier and moisturization of subjects living in arid and humid regions in summer as well as in winter. Results from in vitro experiments showed that 50 mM sorbitol protected epidermal keratinocytes from osmotic toxicity induced by sodium chloride. Clinical studies indicated that skin chronically exposed to hot, dry environment appeared to exhibit stronger skin barrier and a lower baseline TEWL. In addition, skin barrier was stronger in summer than in winter. Sorbitol exhibited significant improvement in both barrier repair and moisturization, especially in individuals subjected to arid environmental conditions.

  3. Effect of microneedle geometry and supporting substrate on microneedle array penetration into skin.

    PubMed

    Kochhar, Jaspreet Singh; Quek, Ten Cheer; Soon, Wei Jun; Choi, Jaewoong; Zou, Shui; Kang, Lifeng

    2013-11-01

    Microneedles are being fast recognized as a useful alternative to injections in delivering drugs, vaccines, and cosmetics transdermally. Owing to skin's inherent elastic properties, microneedles require an optimal geometry for skin penetration. In vitro studies, using rat skin to characterize microneedle penetration in vivo, require substrates with suitable mechanical properties to mimic human skin's subcutaneous tissues. We tested the effect of these two parameters on microneedle penetration. Geometry in terms of center-to-center spacing of needles was investigated for its effect on skin penetration, when placed on substrates of different hardness. Both hard (clay) and soft (polydimethylsiloxane, PDMS) substrates underneath rat skin and full-thickness pig skin were used as animal models and human skins were used as references. It was observed that there was an increase in percentage penetration with an increase in needle spacing. Microneedle penetration with PDMS as a support under stretched rat skin correlated better with that on full-thickness human skin, while penetration observed was higher when clay was used as a substrate. We showed optimal geometries for efficient penetration together with recommendation for a substrate that could better mimic the mechanical properties of human subcutaneous tissues, when using microneedles fabricated from poly(ethylene glycol)-based materials.

  4. Photo- and gas-tuned, reversible thermoelectric properties and anomalous photo-thermoelectric effects of platinum-loaded tungsten trioxide

    NASA Astrophysics Data System (ADS)

    Suzuki, Kenta; Watanabe, Takuya; Kakemoto, Hirofumi; Irie, Hiroshi

    2016-06-01

    We report the photo- and gas-controllable properties of platinum-loaded tungsten trioxide (Pt/WO3), which is of interest for developing practical applications of WO3 as well as for interpreting such phenomena from scientific viewpoints. Here, a Pt/WO3 thin film generated a thermoelectric power due to the ultraviolet-light-induced band-gap excitation (photochromic (PC) reaction) and/or dark storage in formic acid vapor (gaschromic (GC) reaction) in the absence of O2, resulting from the generation of W5+ ions. After such chromic reactions, the electrical conductivity (σ) is increased, whereas the absolute value of the Seebeck coefficient (S) is decreased. The changes in σ and S and their rate of change for consistency increased in the order of: during the PC reaction < during the GC reaction < during simultaneous PC and GC reactions. The opposite behaviors, a decrease in σ and an increase in S, were exhibited by Pt/WO3 in the presence of O2 after dark storage or visible-light irradiation. This reversible cycle could be repeated. Moreover, anomalous, nontrivial photo-thermoelectric effects (a photoconductive effect (photoconductivity, σphoto) and a photo-Seebeck effect (photo-Seebeck coefficient, Sphoto)) were also detected in response to the visible-light irradiation of Pt/WO3 in the absence of O2 after chromic reactions. Under visible-light irradiation, both σphoto and the absolute value of Sphoto are increased. After the irradiation, both values were decreased, that is, σ and the absolute value of S were smaller than σphoto and the absolute value of Sphoto, respectively. These effects are likely to be due to the photoinduced charge carriers and the accumulated electrons in Pt contributing to the increase in σphoto. In addition, electrons are extracted from the W5+ state, decreasing the number of W5+ in HxWO3 and thus contributing to the increase in Sphoto. After light irradiation, the accumulated electrons in Pt are returned to the energetically favorable W

  5. Berry phase mechanism of the anomalous Hall effect in a disordered two-dimensional magnetic semiconductor structure

    PubMed Central

    Oveshnikov, L. N.; Kulbachinskii, V. A.; Davydov, A. B.; Aronzon, B. A.; Rozhansky, I. V.; Averkiev, N. S.; Kugel, K. I.; Tripathi, V.

    2015-01-01

    The anomalous Hall effect (AHE) arises from the interplay of spin-orbit interactions and ferromagnetic order and is a potentially useful probe of electron spin polarization, especially in nanoscale systems where direct measurement is not feasible. While AHE is rather well-understood in metallic ferromagnets, much less is known about the relevance of different physical mechanisms governing AHE in insulators. As ferromagnetic insulators, but not metals, lend themselves to gate-control of electron spin polarization, understanding AHE in the insulating state is valuable from the point of view of spintronic applications. Among the mechanisms proposed in the literature for AHE in insulators, the one related to a geometric (Berry) phase effect has been elusive in past studies. The recent discovery of quantized AHE in magnetically doped topological insulators - essentially a Berry phase effect - provides strong additional motivation to undertake more careful search for geometric phase effects in AHE in the magnetic semiconductors. Here we report our experiments on the temperature and magnetic field dependences of AHE in insulating, strongly-disordered two-dimensional Mn delta-doped semiconductor heterostructures in the hopping regime. In particular, it is shown that at sufficiently low temperatures, the mechanism of AHE related to the Berry phase is favoured. PMID:26596472

  6. Prediction of high-temperature quantum anomalous Hall effect in two-dimensional transition-metal oxides

    NASA Astrophysics Data System (ADS)

    Wang, H. P.; Luo, Wei; Xiang, H. J.

    2017-03-01

    Quantum anomalous Hall (QAH) insulator is a topological phase which exhibits chiral edge states in the absence of magnetic field. The celebrated Haldane model is the first example of QAH effect (QAHE), but it is difficult to realize. Here, we predict the two-dimensional (2D) single-atomic-layer V2O3 with a honeycomb-Kagome structure is a QAH insulator with a large band gap (larger than 0.1 eV) and a high ferromagnetic Curie temperature (about 900 K). Combining the first principles calculations with the effective Hamiltonian analysis, we find that the spin-majority dx y and dy z orbitals of V atoms on the honeycomb lattice form a massless Dirac cone near the Fermi level which becomes massive when the on-site spin-orbit coupling (SOC) is included. Interestingly, we find that the large band gap is caused by a cooperative effect of electron correlation and SOC. Both first principles calculations and the effective Hamiltonian analysis confirm that 2D V2O3 has a nonzero Chern number (i.e., one). This paper paves a direction toward realizing the QAHE at room temperature.

  7. Berry phase mechanism of the anomalous Hall effect in a disordered two-dimensional magnetic semiconductor structure.

    DOE PAGES

    Oveshnikov, L. N.; Kulbachinskii, V. A.; Davydov, A. B.; ...

    2015-11-24

    In this study, the anomalous Hall effect (AHE) arises from the interplay of spin-orbit interactions and ferromagnetic order and is a potentially useful probe of electron spin polarization, especially in nanoscale systems where direct measurement is not feasible. While AHE is rather well-understood in metallic ferromagnets, much less is known about the relevance of different physical mechanisms governing AHE in insulators. As ferromagnetic insulators, but not metals, lend themselves to gatecontrol of electron spin polarization, understanding AHE in the insulating state is valuable from the point of view of spintronic applications. Among the mechanisms proposed in the literature for AHEmore » in insulators, the one related to a geometric (Berry) phase effect has been elusive in past studies. The recent discovery of quantized AHE in magnetically doped topological insulators - essentially a Berry phase effect - provides strong additional motivation to undertake more careful search for geometric phase effects in AHE in the magnetic semiconductors. Here we report our experiments on the temperature and magnetic field dependences of AHE in insulating, strongly-disordered two-dimensional Mn delta-doped semiconductor heterostructures in the hopping regime. In particular, it is shown that at sufficiently low temperatures, the mechanism of AHE related to the Berry phase is favoured.« less

  8. Berry phase mechanism of the anomalous Hall effect in a disordered two-dimensional magnetic semiconductor structure.

    SciTech Connect

    Oveshnikov, L. N.; Kulbachinskii, V. A.; Davydov, A. B.; Aronzon, B. A.; Rozhansky, I. V.; Averkiev, N. S.; Kugel, K. I.; Tripathi, V.

    2015-11-24

    In this study, the anomalous Hall effect (AHE) arises from the interplay of spin-orbit interactions and ferromagnetic order and is a potentially useful probe of electron spin polarization, especially in nanoscale systems where direct measurement is not feasible. While AHE is rather well-understood in metallic ferromagnets, much less is known about the relevance of different physical mechanisms governing AHE in insulators. As ferromagnetic insulators, but not metals, lend themselves to gatecontrol of electron spin polarization, understanding AHE in the insulating state is valuable from the point of view of spintronic applications. Among the mechanisms proposed in the literature for AHE in insulators, the one related to a geometric (Berry) phase effect has been elusive in past studies. The recent discovery of quantized AHE in magnetically doped topological insulators - essentially a Berry phase effect - provides strong additional motivation to undertake more careful search for geometric phase effects in AHE in the magnetic semiconductors. Here we report our experiments on the temperature and magnetic field dependences of AHE in insulating, strongly-disordered two-dimensional Mn delta-doped semiconductor heterostructures in the hopping regime. In particular, it is shown that at sufficiently low temperatures, the mechanism of AHE related to the Berry phase is favoured.

  9. The effect of skin aging on the percutaneous penetration of chemicals through human skin

    SciTech Connect

    Roskos, K.V.

    1989-01-01

    Despite much research into the mechanisms of cutaneous aging and the identification of significant age-associated biological and biophysical changes within the skin, the question how does aging affect percutaneous absorption (PA) in vivo remains unanswered. The author has made in vivo measurements of PA in young (18-40 years) and old (> 65 years) subjects. Standard radiotracer methodology was employed and PA was quantified from the urinary excretion profiles of {sup 14}C radiolabel (corrected for incomplete renal elimination). Testosterone (TST), estradiol (EST), hydrocortisone (HC), benzoic acid (BA), acetylsalicylic acid (ASA) and caffeine (CAFF) have been studied. Penetration of HC, BA, ASA, and CAFF were significantly lower in aged subjects whereas TST and EST absorption were not distinguishable from the young controls. Thus it appears that aging can affect PA in vivo and that relatively hydrophilic compounds may be most sensitive. Work was done to elucidate whether the observations were related to documented skin aging changes. Cutaneous microcirculation efficiency suspected to decline with increasing age, could not be correlated with the observed penetration changes. However, in vivo infrared spectroscopic studies of aged stratum corneum (SC) reveal a decreased amount of epidermal lipid. The diminished lipid content implies a diminished dissolution medium for compounds administered to the skin surface. They hypothesize that the compounds most affected by a loss of SC lipids would be those compounds whose overall solubility is lowest (compounds with lower octanol-water partition coefficients, eg., HC, BA, ASA and CAFF). Conversely, a diminished lipid content may not affect dissolution into the SC of highly lipophilic compounds (e.g., TST and EST).

  10. Anomalous zones (domal)

    SciTech Connect

    Kupfer, D.H. )

    1990-09-01

    Each zone contains several anomalous salt properties (anomalous features). Zones cannot be characterized by any single property Zones are highly variable, lenticular, and discontinuous in detail; however, once established, they commonly have a predictable trend. The individual anomalous features can occur alone (locally in pairs) over areas of various sizes and shapes. These alone occurrences are not anomalous zones. Anomalous zones may be of any origin, and origin is not part of the definition. Typical origins include: primary (sedimentary), external sheath zone, separating two spines of salt, or caused by toroidal flow. The major importance of an anomalous zone is that it consists of various anomalous features distributed discontinuously along the zone. Thus, if three or more anomalous properties are observed together, one should look for others. The anomalous zones observed in the Gulf Coast thus far are vertical, linear, and semicontinuous. Most are reasonably straight, but some bend sharply, end abruptly, or coalesce. Textures in salt involve grain size, color (white to dark gray), grain shape, or grain distribution of the salt. Typical anomalous textures are coarse-grain, poikiloblastic, and friability. A change in color is commonplace and seldom anomalous. Structural anomalous features, broadly defined, account for most of the rest of the anomalous features. Not uncommonly they cause mining problems. Among the structural anomalous features: INCLUSIONS: Sediments, hydrocarbons, brine, gases. Common gases are air (as N{sub 2}), CH-compounds, CO{sub 2}, and H{sub 2}S. STRUCTURES: Sheared salt, undue stabbing or jointing, voids (crystal-lined pockets), permeability, increased porosity COMPOSITION: High anhydrite content, visible anhydrite as grains or boudins, very black salt = disseminated impurities such as clay.

  11. Effect of microplasma irradiation on skin barrier function

    NASA Astrophysics Data System (ADS)

    Shimizu, Kazuo; Tran, An N.; Blajan, Marius

    2016-07-01

    In this paper, we introduce the feasibility of atmospheric-pressure argon microplasma irradiation (AAMI) to promote percutaneous absorption. A hairless Yucatan micropig skin was used for this ex vivo study. After AAMI, the disturbance in the stratum corneum (SC) lipids was observed using attenuated total reflectance-Fourier transform infrared spectroscopy. Also, an increase in transepidermal water loss and no physical damage on pig skins were confirmed by microscopic observation. These results of AAMI were compared with those of a plasma jet irradiation (PJI) and a tape stripping test (TST) leading to the conclusion that AAMI reduces the barrier function of the skin and could also enhance the transdermal absorption of drugs.

  12. Quantum anomalous Hall effect and a nontrivial spin-texture in ultra-thin films of magnetic topological insulators

    NASA Astrophysics Data System (ADS)

    Duong, Le Quy; Das, Tanmoy; Feng, Y. P.; Lin, Hsin

    2015-05-01

    We study the evolution of quantum anomalous Hall (QAH) effect for a Z2 topological insulator (TI) thin films in a proximity induced magnetic phase by a realistic layered k.p model with interlayer coupling. We examine three different magnetic configurations in which ferromagnetic (FM) layer(s) is added either from one side (FM-TI), from both sides (FM-TI-FM), or homogeneously distributed (magnetically doped) in a TI slab. We map out the thickness-dependent topological phase diagram under various experimental conditions. The critical magnetic exchange energy for the emergence of QAH effect in the latter two cases decreases monotonically with increasing number of quintuple layers (QLs), while it becomes surprisingly independent of the film thickness in the former case. The gap size of the emergent QAH insulator depends on the non-magnetic "parent" gap of the TI thin film and is tuned by the FM exchange energy, opening a versatile possibility to achieve room-temperature QAH insulator in various topological nanomaterials. Finally, we find that the emergent spin-texture in the QAH effect is very unconventional, non-"hedgehog" type; and it exhibits a chiral out-of-plane spin-flip texture within the same valence band which is reminiscent of dynamical "skyrmion" pattern, except our results are in the momentum space.

  13. Influence of an anomalous dimension effect on thermal instability in amorphous-InGaZnO thin-film transistors

    SciTech Connect

    Liu, Kuan-Hsien; Chou, Wu-Ching E-mail: wuchingchou@mail.nctu.edu.tw; Chang, Ting-Chang E-mail: wuchingchou@mail.nctu.edu.tw; Chen, Hua-Mao; Tai, Ya-Hsiang; Tsai, Ming-Yen; Hung, Pei-Hua; Chu, Ann-Kuo; Wu, Ming-Siou; Hung, Yi-Syuan; Hsieh, Tien-Yu; Yeh, Bo-Liang

    2014-10-21

    This paper investigates abnormal dimension-dependent thermal instability in amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. Device dimension should theoretically have no effects on threshold voltage, except for in short channel devices. Unlike short channel drain-induced source barrier lowering effect, threshold voltage increases with increasing drain voltage. Furthermore, for devices with either a relatively large channel width or a short channel length, the output drain current decreases instead of saturating with an increase in drain voltage. Moreover, the wider the channel and the shorter the channel length, the larger the threshold voltage and output on-state current degradation that is observed. Because of the surrounding oxide and other thermal insulating material and the low thermal conductivity of the IGZO layer, the self-heating effect will be pronounced in wider/shorter channel length devices and those with a larger operating drain bias. To further clarify the physical mechanism, fast I{sub D}-V{sub G} and modulated peak/base pulse time I{sub D}-V{sub D} measurements are utilized to demonstrate the self-heating induced anomalous dimension-dependent threshold voltage variation and on-state current degradation.

  14. Quantum anomalous Hall effect and a nontrivial spin-texture in ultra-thin films of magnetic topological insulators

    SciTech Connect

    Duong, Le Quy; Das, Tanmoy; Feng, Y. P.; Lin, Hsin

    2015-05-07

    We study the evolution of quantum anomalous Hall (QAH) effect for a Z{sub 2} topological insulator (TI) thin films in a proximity induced magnetic phase by a realistic layered k·p model with interlayer coupling. We examine three different magnetic configurations in which ferromagnetic (FM) layer(s) is added either from one side (FM-TI), from both sides (FM-TI-FM), or homogeneously distributed (magnetically doped) in a TI slab. We map out the thickness-dependent topological phase diagram under various experimental conditions. The critical magnetic exchange energy for the emergence of QAH effect in the latter two cases decreases monotonically with increasing number of quintuple layers (QLs), while it becomes surprisingly independent of the film thickness in the former case. The gap size of the emergent QAH insulator depends on the non-magnetic “parent” gap of the TI thin film and is tuned by the FM exchange energy, opening a versatile possibility to achieve room-temperature QAH insulator in various topological nanomaterials. Finally, we find that the emergent spin-texture in the QAH effect is very unconventional, non-“hedgehog” type; and it exhibits a chiral out-of-plane spin-flip texture within the same valence band which is reminiscent of dynamical “skyrmion” pattern, except our results are in the momentum space.

  15. In vitro percutaneous absorption of chromium powder and the effect of skin cleanser.

    PubMed

    Larese Filon, Francesca; D'Agostin, Flavia; Crosera, Matteo; Adami, Gianpiero; Bovenzi, Massimo; Maina, Giovanni

    2008-09-01

    The present study tried to investigate, using a synthetic sweat at pH 4.5, whether metallic chromium can pass through the skin (in vitro) and the effect of rapid skin decontamination with a common detergent. A suspension of chromium powder in synthetic sweat at pH 4.5 was prepared and shaken with a stirring plate at room temperature for 30 min. Human skin membranes were set up in Franz-diffusion cells and 1 ml of the freshly made suspension was applied to the outer surface of the skin for 24h. The tests were performed without and with decontamination using the cleanser 30 min after the start of exposure. The appearance of metal ions in the aqueous receptor phase was quantified by Electro Thermal Atomic Absorption Spectroscopy (ETAAS) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). Speciation analysis and measurements of chromium skin content were also performed. Chromium skin permeation was demonstrated in in vitro experiments using the Franz cell system, giving a permeation flux of 0.84+/-0.25 ng cm(-2)h(-1) and a lag time of 1.1+/-0.7h. The cleaning procedure stop Cr permeation but its concentration into the skin significantly increased (Mann-Whitney U test P<0.03). The results revealed that chromium applied as powder can pass through the skin and that decontamination, done after 30 min of exposure, prevent Cr skin permeation but increase Cr content into the skin.

  16. Effectiveness Evaluation of Skin Covers against Intravascular Brachytherapy Sources Using VARSKIN3 Code

    PubMed Central

    Baghani, H R; Nazempour, A R; Aghamiri, S M R; Hosseini Daghigh, S M; Mowlavi, A A

    2013-01-01

    Background and Objective: The most common intravascular brachytherapy sources include 32P, 188Re, 106Rh and 90Sr/90Y. In this research, skin absorbed dose for different covering materials in dealing with these sources were evaluated and the best covering material for skin protection and reduction of absorbed dose by radiation staff was recognized and recommended. Method: Four materials including polyethylene, cotton and two different kinds of plastic were proposed as skin covers and skin absorbed dose at different depths for each kind of the materials was calculated separately using the VARSKIN3 code. Results: The results suggested that for all sources, skin absorbed dose was minimized when using polyethylene. Considering this material as skin cover, maximum and minimum doses at skin surface were related to 90Sr/90Y and 106Rh, respectively. Conclusion: polyethylene was found the most effective cover in reducing skin dose and protecting the skin. Furthermore, proper agreement between the results of VARSKIN3 and other experimental measurements indicated that VRASKIN3 is a powerful tool for skin dose calculations when working with beta emitter sources. Therefore, it can be utilized in dealing with the issue of radiation protection. PMID:25505758

  17. Ultraviolet radiation effects on the proteome of skin cells.

    PubMed

    Muller, H Konrad; Woods, Gregory M

    2013-01-01

    Proteomic studies to date have had limited use as an investigative tool in the skin's response to UV radiation. These studies used cell lines and reconstructed skin and have shown evidence of cell injury with oxidative damage and stress induced heat shock proteins. Others changes included altered cytokeratin and cytoskeletal proteins with enhanced expression of TRIM29 as the keratinocytes regenerate. The associated DNA repair requires polη, Rad18/Rad16 and Rev1. In the whole animal these events would be associated with inflammation, remodelling of the epidermis and modulation of the immune response. Longer term changes include ageing and skin cancers such as melanoma, squamous cell carcinoma and basal cell carcinoma. In the future proteomics will be used to explore these important aspects of photobiology. Better characterisation of the proteins involved should lead to a greater understanding of the skin's response to UV radiation.

  18. Photobleaching effects on in vivo skin autofluorescence lifetime

    NASA Astrophysics Data System (ADS)

    Ferulova, Inesa; Lihachev, Alexey; Spigulis, Janis

    2015-05-01

    The autofluorescence lifetime of healthy human skin was measured using excitation provided by a picosecond diode laser operating at a wavelength of 405 nm and with fluorescence emission collected at 475 and 560 nm. In addition, spectral and temporal responses of healthy human skin and intradermal nevus in the spectral range 460 to 610 nm were studied before and after photobleaching. A decrease in the autofluorescences lifetimes changes was observed after photobleaching of human skin. A three-exponential model was used to fit the signals, and under this model, the most significant photoinduced changes were observed for the slowest lifetime component in healthy skin at the spectral range 520 to 610 nm and intradermal nevus at the spectral range 460 to 610 nm.

  19. Forearm skin tissue dielectric constant measured at 300 MHz: effect of changes in skin vascular volume and blood flow.

    PubMed

    Mayrovitz, Harvey N; Guo, Xiaoran; Salmon, Mark; Uhde, Matt

    2013-01-01

    Skin tissue dielectric constant (TDC) values measured via the open-ended coaxial probe method are useful non-invasive indices of local skin tissue water. However, the effect of skin blood flow (SBF) or skin blood volume (SBV) on TDC values is unknown. To determine the magnitude of such effects, we decreased forearm SBV via vertical arm raising for 5 min (test 1) and increased SBV by bicep cuff compression to 50 mmHg for 5 min (test 2) in 20 healthy supine subjects (10 men). TDC values were measured to a depth of 1·5 mm on anterior forearm, and SBF was measured with laser-Doppler system simultaneously on forearm and finger. Results indicate that decreasing vascular volume (test 1) was associated with a small but statistically significant reduction in TDC (3·0 ± 4·3%, P = 0·003) and increasing vascular volume (test 2) was associated with a slight but statistically significant increase in TDC (3·5 ± 3·0%, P<0·001). SBF changes depended on test and measurement site. For forearm, test 1 significantly increased SBF (102·6 ± 156·2%, P<0·001) and test 2 significantly decreased it (39·5 ± 13·1%, P<0·001). In finger, SBF was significantly reduced by both tests: in test 1 by 55·3 ± 32·1%, P<0·001 and in test 2 by 53·3 ± 27·6%, P<0·001. We conclude that the small percentage changes in TDC values (3·0-3·5%) over the wide range of induced SBV and SBF changes suggest a minor effect on clinically determined TDC values because of SBV or SBF changes or differences when comparing TDC longitudinally over time or among individuals of different groups in a research setting.

  20. Allergic Responses Induced by the Immunomodulatory Effects of Nanomaterials upon Skin Exposure

    PubMed Central

    Yoshioka, Yasuo; Kuroda, Etsushi; Hirai, Toshiro; Tsutsumi, Yasuo; Ishii, Ken J.

    2017-01-01

    Over the past decade, a vast array of nanomaterials has been created through the development of nanotechnology. With the increasing application of these nanomaterials in various fields, such as foods, cosmetics, and medicines, there has been concern about their safety, that is, nanotoxicity. Therefore, there is an urgent need to collect information about the biological effects of nanomaterials so that we can exploit their potential benefits and design safer nanomaterials, while avoiding nanotoxicity as a result of inhalation or skin exposure. In particular, the immunomodulating effect of nanomaterials is one of most interesting aspects of nanotoxicity. However, the immunomodulating effects of nanomaterials through skin exposure have not been adequately discussed compared with the effects of inhalation exposure, because skin penetration by nanomaterials is thought to be extremely low under normal conditions. On the other hand, the immunomodulatory effects of nanomaterials via skin may cause severe problems for people with impaired skin barrier function, because some nanomaterials could penetrate the deep layers of their allergic or damaged skin. In addition, some studies, including ours, have shown that nanomaterials could exhibit significant immunomodulating effects even if they do not penetrate the skin. In this review, we summarize our current knowledge of the allergic responses induced by nanomaterials upon skin exposure. First, we discuss nanomaterial penetration of the intact or impaired skin barrier. Next, we describe the immunomodulating effects of nanomaterials, focusing on the sensitization potential of nanomaterials and the effects of co-exposure of nanomaterials with substances such as chemical sensitizers or allergens, on the onset of allergy, following skin exposure. Finally, we discuss the potential mechanisms underlying the immunomodulating effects of nanomaterials by describing the involvement of the protein corona in the interaction of

  1. Sunscreen effects in skin analyzed by photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    dos Anjos, Fernanda H.; Rompe, Paula C. B.; Batista, Roberta R.; Martin, Airton A.; Mansanares, Antonio M.; da Silva, Edson C.; Acosta-Avalos, Daniel; Barja, Paulo R.

    2004-06-01

    In the photoacoustic technique, the signal is proportional to the heat produced in a sample as a consequence of modulated light absorption. This technique allows the spectroscopic characterization of multilayer systems: as the thermal diffusion length varies with the light modulation frequency, one can obtain the depth profile of the sample by analyzing the frequency-dependence of the signal. As the photoacoustic signal depends on thermal and optical properties of the sample, structural changes in the system under analysis account for signal variations in time. In this work, photoacoustic spectroscopy was used to characterize samples of sunscreen and the system formed by sunscreen plus skin. We used photoacoustic spectroscopy to monitor the absorption kinetics of sunscreen applied to samples of human skin, characterizing alterations in the human skin after application of sunscreen. Measurements used 250W Xe arc lamp as light source, for wavelengths between 240nm and 400nm. This range corresponds to most of the UV radiation that reaches Earth. Skin samples were about 0,5cm diameter. The absorption spectra of sunscreen was obtained. Finally, photoacoustics was employed to monitor the absorption kinetics of the sunscreen applied to skin samples. This was done by applying sunscreen in a skin sample and recording the photoacoustic spectra in regular time intervals, up to 90 minutes after application. According to measurements, light absorption by the system sunscreen plus skin stabilizes between 25 and 45 minutes after sunscreen application. Results show that this technique can be utilized to monitor drug delivery and farmacokinetics in skin samples.

  2. Effects of hair removal alexandrite laser on biometric parameters of the skin.

    PubMed

    Alavi, Shiva; Abolhasani, Ehsan; Nilforoushzadeh, Mohammadali

    2016-04-01

    The effects of alexandrite laser (AL) on skin parameters such as melanin content, skin layer depth, elasticity, and density have not been investigated through biometric methods. We aim to assess the effect of AL on the skin parameters through biometric devices to determine whether it has positive effects on treated region. In this pretest-posttest study, we recruited patients who attended Laser Clinic of Skin and Stem Cell Research Center, Tehran University of Medical Sciences, Tehran, Iran, from January through December 2014. Patients had to be free of any dermatologic conditions and lesion at the site of treatment or any contraindication to laser therapy. Baseline measurements were performed and patients received four sessions of AL therapy (spot size, 12 mm; fluence, 12 J/cm(2); and pulse width, 5 Hz) with 4-week intervals. Four weeks after the last treatment session, the same parameters were assessed that included skin color, transepidermal water loss (TEWL), dermis and epidermis density and depth (through skin ultrasonography), melanin content, erythema intensity, and skin elasticity. Biometric parameters of 33 patients (27 females [81.8%]), with mean (SD) age of 35.7 (9.5) years were evaluated. The mean percent changes of skin parameters were as follows: skin color, 5.88% through Visioface and by 56.8% through Colorimeter devices (became lighter); melanin content, -15.95%; TEWL, -2.96%; elasticity, +14.88%; dermis depth -19.01%; and dermis density, +1580.11% (P < 0.001 for changes in each parameter). AL could decrease melanin content of the skin and make the skin thinner while it could increase elasticity and density of epidermis and dermis, which might indicate increased collagen content of skin.

  3. The Effect of an Emollient Containing Urea, Ceramide NP, and Lactate on Skin Barrier Structure and Function in Older People with Dry Skin.

    PubMed

    Danby, Simon G; Brown, Kirsty; Higgs-Bayliss, Tim; Chittock, John; Albenali, Lujain; Cork, Michael J

    2016-01-01

    Xerosis affects up to 75% of older people and develops as a result of a skin barrier defect. Emollients are widely used to treat xerosis; however, there is limited understanding of the differences between them and their effects on the skin barrier in older people. This study aimed to compare the effect of a commercially available emollient containing 5% urea, ceramide NP and lactate (test emollient) to an alternative emollient without these additives (control emollient) on the properties of the skin barrier in older people. Two cohorts of 21 volunteers aged >60 years with dry skin were recruited. The first applied the test emollient to one forearm and no treatment to the other for 28 days. The second compared the test emollient to the control emollient observing the same parameters. Effects on the skin barrier were determined by measuring skin barrier function, hydration, skin surface pH and by analysing Fourier transform infrared spectra before and after treatment. A third cohort of 6 young adults was recruited to investigate the effect of a single treatment with the test emollient on the molecular structure of the skin barrier at greater depths by employing the tape-stripping technique. The test emollient hydrated the skin to a significantly greater extent and for a longer period of time compared to the control emollient, an effect associated with a significant elevation of carboxylate groups (a marker of natural moisturizing factor content) within the stratum corneum. Furthermore, the test emollient imparted additional benefits to the structure and function of the skin barrier not exhibited by the control emollient. In conclusion, the test emollient addressed the pathological features of xerotic aged skin, supporting its use as first-line therapy for xerotic skin conditions in this population.

  4. Anomalous Earth flybys of spacecraft

    NASA Astrophysics Data System (ADS)

    Wilhelm, Klaus; Dwivedi, Bhola N.

    2015-07-01

    A small deviation from the potential is expected for the gravitational interaction of extended bodies. It is explained as a consequence of a recently proposed gravitational impact model (Wilhelm et al. in Astrophys. Space Sci. 343:135-144, 2013) and has been applied to anomalous perihelion advances by Wilhelm and Dwivedi (New Astron. 31:51-55, 2014). The effect—an offset of the effective gravitational centre from the geometric centre of a spherical symmetric body—might also be responsible for the observed anomalous orbital energy gains and speed increases during Earth flybys of several spacecraft. However, close flybys would require detailed considerations of the orbit geometry. In this study, an attempt is made to explain the anomalous Earth flybys of the Galileo, NEAR Shoemaker and Rosetta spacecraft.

  5. Proinflammatory Effects of Diesel Exhaust Nanoparticles on Scleroderma Skin Cells

    PubMed Central

    Mastrofrancesco, A.; Alfè, M.; Rosato, E.; Gargiulo, V.; Beatrice, C.; Di Blasio, G.; Zhang, B.; Su, D. S.; Picardo, M.; Fiorito, S.

    2014-01-01

    Autoimmune diseases are complex disorders of unknown etiology thought to result from interactions between genetic and environmental factors. We aimed to verify whether environmental pollution from diesel engine exhaust nanoparticulate (DEP) of actually operating vehicles could play a role in the development of a rare immune-mediated disease, systemic sclerosis (SSc), in which the pathogenetic role of environment has been highlighted. The effects of carbon-based nanoparticulate collected at the exhaust of newer (Euro 5) and older (Euro 4) diesel engines on SSc skin keratinocytes and fibroblasts were evaluated in vitro by assessing the mRNA expression of inflammatory cytokines (IL-1α, IL-6, IL-8, and TNF-α) and fibroblast chemical mediators (metalloproteases 2, 3, 7, 9, and 12; collagen types I and III; VEGF). DEP was shown to stimulate cytokine gene expression at a higher extent in SSc keratinocytes versus normal cells. Moreover, the mRNA gene expression of all MMPs, collagen types, and VEGF genes was significantly higher in untreated SSc fibroblasts versus controls. Euro 5 particle exposure increased the mRNA expression of MMP-2, -7, and -9 in SSc fibroblasts in a dose dependent manner and only at the highest concentration in normal cells. We suggest that environmental DEP could trigger the development of SSc acting on genetically hyperreactive cell systems. PMID:24982919

  6. The Effects of Dietary Macronutrient Balance on Skin Structure in Aging Male and Female Mice

    PubMed Central

    McMahon, Aisling C.; Ruohonen, Kari; Raubenheimer, David; Ballard, J. William O.; Le Couteur, David G.; Nicholls, Caroline; Li, Zhe; Maitz, Peter K. M.; Wang, Yiwei; Simpson, Stephen J.

    2016-01-01

    Nutrition influences skin structure; however, a systematic investigation into how energy and macronutrients (protein, carbohydrate and fat) affects the skin has yet to be conducted. We evaluated the associations between macronutrients, energy intake and skin structure in mice fed 25 experimental diets and a control diet for 15 months using the Geometric Framework, a novel method of nutritional analysis. Skin structure was associated with the ratio of dietary macronutrients eaten, not energy intake, and the nature of the effect differed between the sexes. In males, skin structure was primarily associated with protein intake, whereas in females carbohydrate intake was the primary correlate. In both sexes, the dermis and subcutaneous fat thicknesses were inversely proportional. Subcutaneous fat thickness varied positively with fat intake, due to enlarged adipocytes rather than increased adipocyte number. We therefore demonstrated clear interactions between skin structure and macronutrient intakes, with the associations being sex-specific and dependent on dietary macronutrient balance. PMID:27832138

  7. Effect of chicken skin on the quality characteristics of semi-dried restructured jerky.

    PubMed

    Choi, Yun-Sang; Han, Doo-Jeong; Choi, Ji-Hun; Hwang, Ko-Eun; Song, Dong-Heon; Kim, Hyun-Wook; Kim, Young-Boong; Kim, Cheon-Jei

    2016-05-01

    The objective of this study was to evaluate the effect of skin on the textural properties of semi-dried jerky produced with different acid treatments. Jerky was prepared with no skin (control) or with 1, 3, or 5% chicken skin. After hand mixing (for 3 min) and tumbling (for 30 min) to distribute the curing ingredients, the cured meats were dried for 180 min at 55°C, for 180 min at 65°C, and finally for 60 min at 75°C. The presence of skin was shown to result in a higher fat content, TBA value, and metmyoglobin due to the high fat content of the skin. In contrast, acid treatment decreased the TBA value and metmyoglobin in jerky relative to samples that were not subjected to acid treatment. The presence of skin also improved the moisture contents, processing yields, and mechanical tenderness.

  8. Preventive effect of antihistaminics on mouse skin photosensitization with hematoporphyrin derivative

    NASA Astrophysics Data System (ADS)

    Fu, Nai-wu; Yan, Li-xue

    1993-03-01

    Beta-carotene 100 mg/kg per day or vitamin C 50 mg/kg per day was administered orally for two days and did not prevent mouse skin photosensitization caused by hematoporphyrin derivative (HpD). However, (beta) -carotene 100 mg/kg per day administered intramuscularly for two days prevented mouse skin reaction. Cimetidine and benadryl 10 mg/kg per day, P.O.X 2, effectively prevented mouse skin reaction. This suggests histamine may be involved in skin photoreaction induced by HpD.

  9. Electrochemical characterization of human skin by impedance spectroscopy: the effect of penetration enhancers.

    PubMed

    Kontturi, K; Murtomäki, L; Hirvonen, J; Paronen, P; Urtti, A

    1993-03-01

    The electrochemical properties of human cadaver skin were studied in a diffusion cell with impedance spectroscopy as a function of time in the absence and presence of penetration enhancers dodecyl N,N-dimethylamino acetate and Azone. An improved electrochemical model of skin is presented, and combining the novel model with modern fractal mathematics, the effect of enhancers on the surface of skin is demonstrated. The enhancers appeared to open new penetration routes and increase the ohmic resistance, capacitive properties, and fractal dimension of skin, which means a rougher or more heterogeneous surface.

  10. Anomalous Structural Transition and Electrical Transport Behaviors in Compressed Zn2SnO4: Effect of Interface

    PubMed Central

    Zhang, Haiwa; Ke, Feng; Li, Yan; Wang, Li; Liu, Cailong; Zeng, Yi; Yao, Mingguang; Han, Yonghao; Ma, Yanzhang; Gao, Chunxiao

    2015-01-01

    The interface effect is one of the most important factors that strongly affect the structural transformations and the properties of nano-/submicro-crystals under pressure. However, characterization of the granular boundary changes in materials is always challenging. Here, using tetrakaidecahedral Zn2SnO4 microcrystals as an example, we employed alternating current impedance, X-ray diffraction methods and transmission electron microscopy to elucidate the effect of the interface on the structure and electrical transport behavior of the Zn2SnO4 material under pressure. We clearly show that grain refinement of the initial microcrystals into nanocrystals (approximately 5 nm) occurs at above 12.5 GPa and is characterized by an anomalous resistance variation without a structural phase transition. A new phase transition pathway from the cubic to hexagonal structure occurs at approximately 29.8 GPa in Zn2SnO4. The unexpected grain refinement may explain the new structural transition in Zn2SnO4, which is different from the previous theoretical prediction. Our results provide new insights into the link between the structural transition, interface changes and electrical transport properties of Zn2SnO4. PMID:26399167

  11. Quantum spin-quantum anomalous Hall effect with tunable edge states in Sb monolayer-based heterostructures

    NASA Astrophysics Data System (ADS)

    Zhou, Tong; Zhang, Jiayong; Xue, Yang; Zhao, Bao; Zhang, Huisheng; Jiang, Hua; Yang, Zhongqin

    2016-12-01

    A novel topological insulator with tunable edge states, called a quantum spin-quantum anomalous Hall (QSQAH) insulator, is predicted in a heterostructure of a hydrogenated Sb (S b2H ) monolayer on a LaFe O3 substrate by using ab initio methods. The substrate induces a drastic staggered exchange field in the S b2H film, which plays an important role to generate the QSQAH effect. A topologically nontrivial band gap (up to 35 meV) is opened by Rashba spin-orbit coupling, which can be enlarged by strain and an electric field. To understand the underlying physical mechanism of the QSQAH effect, a tight-binding model based on px and py orbitals is constructed. With the model, the exotic behaviors of the edge states in the heterostructure are investigated. Dissipationless chiral charge edge states related to one valley are found to emerge along both sides of the sample, whereas low-dissipation spin edge states related to the other valley flow only along one side of the sample. These edge states can be tuned flexibly by polarization-sensitive photoluminescence controls and/or chemical edge modifications. Such flexible manipulations of the charge, spin, and valley degrees of freedom provide a promising route towards applications in electronics, spintronics, and valleytronics.

  12. Effect of emulsification on the skin permeation and UV protection of catechin.

    PubMed

    Yoshino, Sachie; Mitoma, Tomoaki; Tsuruta, Keiko; Todo, Hiroaki; Sugibayashi, Kenji

    2014-06-01

    An anti-aging effect may be obtained by skin application of tea catechins (Camellia sinensis) since they have high ultraviolet (UV)-protection activity. In this study, the skin permeation of catechin (C), epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECg) and epigallocatechin gallate (EGCg) was determined and compared, and the effect of emulsification on the skin permeation of C was measured. The UV-protective effect of C was also determined. The in vitro skin permeability of each catechin derivative was determined using side-by-side diffusion of cells. The UV-protective effect of C was determined by applying different concentrations of C to the solution or emulsion on a three-dimensional cultured human skin model or normal human epidermal keratinocytes with UV-irradiation. ECg and EGCg with gallate groups showed lower skin permeability than C, EC and EGC without gallate groups, suggesting that the skin permeability of catechin derivatives may be dependent on the existence of a gallate group. Interestingly, the skin permeation of C was increased by an o/w emulsification. In addition, the C emulsion showed a significantly higher UV-protective effect by C than that with its aqueous solution. These results suggest that the o/w emulsion of catechin derivatives is probably useful as a cosmetic formulation with anti-aging efficacy.

  13. Shining light on skin pigmentation: the darker and the brighter side of effects of UV radiation.

    PubMed

    Maddodi, Nityanand; Jayanthy, Ashika; Setaluri, Vijayasaradhi

    2012-01-01

    The term barrier function as applied to human skin often connotes the physical properties of this organ that provides protection from its surrounding environment. This term does not generally include skin pigmentation. However, skin pigmentation, which is the result of melanin produced in melanocytes residing in the basal layer of the skin and exported to the keratinocytes in the upper layers, serves equally important protective function. Indeed, changes in skin pigmentation are often the most readily recognized indicators of exposure of skin to damaging agents, especially to natural and artificial radiation in the environment. Several recent studies have shed new light on (1) the mechanisms involved in selective effects of subcomponents of UV radiation on human skin pigmentation and (2) the interactive influences between keratinocytes and melanocytes, acting as "epidermal melanin unit," that manifest as changes in skin pigmentation in response to exposure to various forms of radiation. This article provides a concise review of our current understanding of the effects of the nonionizing solar radiation, at cellular and molecular levels, on human skin pigmentation.

  14. β-irradiation (166Ho patch)-induced skin injury in mini-pigs: effects on NF-κB and COX-2 expression in the skin

    PubMed Central

    Rhim, Kyung-Jin; Jang, Won-Seok; Lee, Sun-Joo; Son, Yeonghoon; Lee, Seung-Sook; Park, Sunhoo

    2015-01-01

    In the present study, the detrimental effect of β-emission on pig skin was evaluated. Skin injury was modeled in mini-pigs by exposing the animals to 50 and 100 Gy of β-emission delivered by 166Ho patches. Clinicopathological and immunohistochemical changes in exposed skin were monitored for 18 weeks after β-irradiation. Radiation induced desquamation at 2~4 weeks and gradual repair of this damage was evident 6 weeks after irradiation. Changes in basal cell density and skin depth corresponded to clinically relevant changes. Skin thickness began to decrease 1 week after irradiation, and the skin was thinnest 4 weeks after irradiation. Skin thickness increased transiently during recovery from irradiation-induced skin injury, which was evident 6~8 weeks after irradiation. Epidermal expression of nuclear factor-kappa B (NF-κB) differed significantly between the untreated and irradiated areas. One week after irradiation, cyclooxygenase-2 (COX-2) expression was mostly limited to the basal cell layer and scattered among these cells. High levels of COX-2 expression were detected throughout the full depth of the skin 4 weeks after irradiation. These findings suggest that NF-κB and COX-2 play roles in epidermal cell regeneration following β-irradiation of mini-pig skin. PMID:24962420

  15. Using a Cell Phone to Investigate the Skin Depth Effect in Salt Water

    NASA Astrophysics Data System (ADS)

    Rayner, John

    2017-02-01

    This paper describes an experimental investigation of the skin depth effect for electromagnetic waves in salt water using a cell phone that is immersed to a critical depth where it no longer responds when called. We show that this critical depth is directly proportional to the theoretical skin depth for a range of salt concentrations.

  16. Anomalous enhancement and suppression of ionization induced by an effective few-cycle pulse in the frequency domain

    NASA Astrophysics Data System (ADS)

    Foote, David; Lin, Yingda; Hill, Wendell T., III

    2015-05-01

    In a recent set of coherent control experiments, an anomalous sinusoidal variation of the ionization yield was observed in Xe when ionized by a pairs of phase-locked, many-cycle 800 nm pulses. Compared with the signal of a single transform limited pulse, both enhancement and suppression was possible, which depended on the temporal separation and relative phase of the pulses. In the time domain, the control can be viewed as a temporal Young's double slit experiment - two coherent electron wavepackets interfering. In the frequency domain, the photoelectron spectrum is given by the modulus squared of the Fourier transform of the field, which is a few-cycle squared sinusodial function. In analogy to a few-cycle pulse where the carrier phase dictates the ejection direction of rescattered electrons, enhancement (suppression) occurs when the effective carrier waveform is cos[w-w0]2 (sin[w-w0]2). The contrast decreased with increasing pulse separation and decreasing multiphoton order. Detailed results and a model simulation will be presented.

  17. Conetronics in 2D metal-organic frameworks: double/half Dirac cones and quantum anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Wu, Menghao; Wang, Zhijun; Liu, Junwei; Li, Wenbin; Fu, Huahua; Sun, Lei; Liu, Xin; Pan, Minghu; Weng, Hongming; Dincă, Mircea; Fu, Liang; Li, Ju

    2017-03-01

    Bandstructure with Dirac cones gives rise to massless Dirac fermions with rich physics, and here we predict rich cone properties in M 3C12S12 and M 3C12O12, where M = Zn, Cd, Hg, Be, or Mg based on recently synthesized Ni3C12S12—class 2D metal-organic frameworks (MOFs). For M 3C12S12, their band structures exhibit double Dirac cones with different Fermi velocities that are n (electron) and p (hole) type, respectively, which are switchable by few-percent strain. The crossing of two cones are symmetry-protected to be non-hybridizing, leading to two independent channels at the same k-point akin to spin-channels in spintronics, rendering ‘conetronics’ device possible. For M 3C12O12, together with conjugated metal-tricatecholate polymers M 3(HHTP)2, the spin-polarized slow Dirac cone center is pinned precisely at the Fermi level, making the systems conducting in only one spin/cone channel. Quantum anomalous Hall effect can arise in MOFs with non-negligible spin-orbit coupling like Cu3C12O12. Compounds of M 3C12S12 and M 3C12O12 with different M, can be used to build spin/cone-selecting heterostructure devices tunable by strain or electrostatic gating, suggesting their potential applications in spintroincs/conetronics.

  18. Anomalous correlation effects and unique phase diagram of electron-doped FeSe revealed by photoemission spectroscopy

    PubMed Central

    Wen, C. H. P.; Xu, H. C.; Chen, C.; Huang, Z. C.; Lou, X.; Pu, Y. J.; Song, Q.; Xie, B. P.; Abdel-Hafiez, Mahmoud; Chareev, D. A.; Vasiliev, A. N.; Peng, R.; Feng, D. L.

    2016-01-01

    FeSe layer-based superconductors exhibit exotic and distinctive properties. The undoped FeSe shows nematicity and superconductivity, while the heavily electron-doped KxFe2−ySe2 and single-layer FeSe/SrTiO3 possess high superconducting transition temperatures that pose theoretical challenges. However, a comprehensive study on the doping dependence of an FeSe layer-based superconductor is still lacking due to the lack of a clean means of doping control. Through angle-resolved photoemission spectroscopy studies on K-dosed thick FeSe films and FeSe0.93S0.07 bulk crystals, here we reveal the internal connections between these two types of FeSe-based superconductors, and obtain superconductivity below ∼46 K in an FeSe layer under electron doping without interfacial effects. Moreover, we discover an exotic phase diagram of FeSe with electron doping, including a nematic phase, a superconducting dome, a correlation-driven insulating phase and a metallic phase. Such an anomalous phase diagram unveils the remarkable complexity, and highlights the importance of correlations in FeSe layer-based superconductors. PMID:26952215

  19. Disorder-induced WAL-WL transition and anomalous Hall effect in undoped thin Sb2Te3 films

    NASA Astrophysics Data System (ADS)

    Korzhovska, Inna; Deshko, Yury; Zhao, Lukas; Chen, Zhiyi; Krusin-Ebaum, Lia; Raoux, Simone

    We examine the effects of disorder on charge transport in thin (20-50 nm) films of topological insulator (TI) Sb2Te3, where, uniquely, structural disorder can be controllably tuned over a huge range - from amorphous to crystalline - by a suitable annealing schedule. We report on the observation of disorder-induced transition from weak localization-like state (WL-like) to weak anti-localization (WAL), at which conductance changes its character from 3D in the WL-like state to 2D in the WAL (crystalline) state. Near the transition, the conductance is G ~e2 / h , suggestive of the transport through a surface channel that is decoupled from the bulk by disorder. Quite remarkably, the onset of the WL state (where bulk transport is of variable range hopping type) is found to be concurrent with the appearance of anomalous Hall signal (AHE) which grows with increased disorder, with Hall resistivity ρxy scaling as the longitudinal resistivity squared, ρxy ~ρxx2 . The nature of spin correlations (probed directly by the arrays of micro Hall sensors) responsible for AHE in disordered TI films in the absence of magnetic dopants will be discussed. Supported by NSF-DMR-1420634, NSF-DMR-1312483-MWN, and DOD-W911NF-13-1-0159.

  20. Ultrahigh sensitivity of anomalous Hall effect sensor based on Cr-doped Bi2Te3 topological insulator thin films

    DOE PAGES

    Ni, Y.; Zhang, Z.; Nlebedim, I. C.; ...

    2016-07-01

    Anomalous Hall effect (AHE) was recently discovered in magnetic element-doped topological insulators (TIs), which promises low power consumption and high efficiency spintronics and electronics. This discovery broadens the family of Hall sensors. In this paper, AHE sensors based on Cr-doped Bi2Te3 topological insulator thin films are studied with two thicknesses (15 and 65 nm). It is found, in both cases, that ultrahigh Hall sensitivity can be obtained in Cr-doped Bi2Te3. Hall sensitivity reaches 1666 Ω/T in the sensor with the 15 nm TI thin film, which is higher than that of the conventional semiconductor HE sensor. The AHE of 65more » nm sensors is even stronger, which causes the sensitivity increasing to 2620 Ω/T. Furthermore, after comparing Cr-doped Bi2Te3 with the previously studied Mn-doped Bi2Te3 TI Hall sensor, the sensitivity of the present AHE sensor shows about 60 times higher in 65 nm sensors. Furthermore, the implementation of AHE sensors based on a magnetic-doped TI thin film indicates that the TIs are good candidates for ultrasensitive AHE sensors.« less

  1. Skin (Pressure) Sores

    MedlinePlus

    ... Treatments and Side Effects Managing Cancer-related Side Effects Skin Problems Pressure Sores A skin or pressure sore ... Content Usage Policy . Skin Problems Dry Skin Itching Skin Color Changes Pressure Sores Scars ... and Paying for Treatment Treatments and Side Effects Survivorship: During and After Treatment Caregivers and Family ...

  2. Theoretical Investigation on Skin Effect Factor of Conductor in Power Cables

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Kanaoka, Mamoru

    This paper describes a newly-derived theoretical equation on the skin effect factor of power cables, and its application to large-size OF and XLPE cables with segmental conductors, including insulated wires. The skin effect factors calculated with the new equation were fit very well to measurements in wide range conductor sizes. In the new equation, the important factor which characterizes the skin effect of segmental conductors is the `equivalent conductivity ratio' ν defined by the ratio of longitudinal conductivity in axial direction of conductor to conductivity of conductor wires. Since the obtained ratio ν in XLPE cable was three times greater than that in OF cable, the larger longitudinal eddy current passing from a wire to another increased the eddy current loss in conductor, which increased the conductor loss of XLPE cable. The new equation enables us to investigate quantitatively the dominant loss component affecting the skin effect factor. Then, the skin effect factors and coefficients for OF and XLPE cables were investigated with the new equation. It was revealed that the best number of separation, in which the skin effect became minimum, existed in OF and XLPE cables with segmental conductors. In addition, it was confirmed that the skin effect coefficients ks1 calculated with the new equation were consistent well with those used in JCS.

  3. The anomalous Hall effect and related transport phenomena in ferromagnetic spinel copper chromium selenium bromide, manganese-doped chalcopyrite copper gallium ditelluride, and ruthenate bismuth ruthenate

    NASA Astrophysics Data System (ADS)

    Lee, Wei-Li

    One of the interesting and unsettled transport phenomena is the, so called, "anomalous Hall Effect". It generally refers to the phenomenon of a non-linear field dependence of the Hall resistivity rhoxy. An emerging idea relates to the "gauge field O" experienced by electrons. It gives rise to Berry phase accumulation. In ferromagnets, a non-vanishing O( k⃗ ) is related to the spin-orbit coupling and the time-reversal asymmetry. We show that, in the ferromagnetic spinel CuCr2Se 4-xBrx, the anomalous Hall conductivity sigma xy (normalized to per carrier, at 5K) remains unchanged with a 1000-fold increase in resistivity. From the anomalous Nernst effect, we uncover a simple relation for the off-diagonal Peltier conductivity tensor alphaxy, which is a measure of a transverse electrical current density generated per unit of applied temperature gradient. They both strongly support the anomalous-velocity theory based on the intrinsic spin-orbit coupling of the electrons. An alternative way to procure O is from the spin-chirality effect. In the Mn-doped chalcopyrite semiconductor CuGaTe2, with a few percent doping, the orbitals of the Mn ions overlap to form an impurity band. Therefore, the electrons will accumulate Berry phase while hopping around the Mn ions that have a non-collinear magnetic ground state. We observed the enhanced and non-monotonic field dependence of rhoxy, which may be understood from the spin-chirality effect. Finally, we studied the Hall effect and thermopower in the ruthenate Bi3Ru3O 11. From the Hall effect, we observed field-tuning of electron and hole populations. We also found a large field dependence of the thermopower at low temperature. The origin of the colossal field-dependence in the thermopower is still an open question, but it is linked to the unusual electronic properties in the Bi3Ru3O11.

  4. Effect of Force of Microneedle Insertion on the Permeability of Insulin in Skin

    PubMed Central

    Cheung, Karmen; Han, Tao

    2014-01-01

    Many experiments conducted in the literature have investigated the effect of microneedles (MNs) on insulin permeation across skin. There are also a number of articles that deal with the effect of MN insertion force in skin. However, there is little known on quantifying the relationship between the effect of MN insertion force and the amount of insulin permeated for given MNs. This issue is addressed in this article. MNs of 1100 µm and 1400 µm are used to conduct in vitro permeability experiments on porcine skin, using insulin. Histological images of MN treated skin are obtained from a microtome and the viscoelastic properties of the skin sample are measured using a rheometer. An in-house insertion force device is utilized that can reproducibly apply a specified force on MNs for a set period of time using compressed air. It is deduced that when porcine skin was pretreated with an applied force of 60.5 N and 69.1 N, the resultant amount of insulin permeated was approximately 3 µg and 25 µg over a 4-hour period for the MNs used. The amount of MN force applied to porcine skin was shown to be related to the amount of insulin permeated. An increase in insertion force increase the amount of insulin permeated. It was also demonstrated that using insufficient force may have reduced or prevented the amount of insulin passing through the skin, regardless of the geometry of the MNs. PMID:24876604

  5. Orally administered ethanol: transepidermal pathways and effects on the human skin barrier.

    PubMed

    Jacobi, Ute; Bartoll, Jens; Sterry, Wolfram; Lademann, Jürgen

    2005-01-01

    Ethanol intake is associated with a variety of skin diseases. The aim of the present study was (1) to identify the pathways of release of orally administered ethanol through the skin, and (2) to investigate the effects of a single oral dose of ethanol on the penetration of topically applied substances into the skin. Ethanol evaporation via the skin was measured using the new technique of ion mobility spectrometry (IMS). Transepidermal water loss (TEWL) and skin surface temperature were simultaneously measured before and after ethanol consumption. Measurements were performed on skin sites with different stratum corneum (SC) thickness, and density of follicles and sweat glands. These appendages were selectively sealed to investigate their participation in ethanol evaporation. The penetration of a topically applied UV filter substance was studied before and after ethanol consumption after removing the SC with adhesive tape. Ethanol evaporation was measured within 5 min of consumption, while the skin surface temperature remained nearly constant. The sealing of the appendages did not have a significant effect on ethanol evaporation. On the forehead, a higher TEWL value was measured than on the forearm. On both skin sites, an increase in TEWL was observed after ethanol ingestion. No influence of orally administered ethanol on the penetration of the topically applied UV filter substance was observed. The results indicate that ethanol evaporation occurs via the lipid layers without a significant effect on the penetration of the topically applied substance.

  6. Oncogenic Radiation Abscopal Effects In Vivo: Interrogating Mouse Skin

    SciTech Connect

    Mancuso, Mariateresa; Leonardi, Simona; Giardullo, Paola; Pasquali, Emanuela; Tanori, Mirella; De Stefano, Ilaria; Casciati, Arianna; Naus, Christian C.; Pazzaglia, Simonetta; Saran, Anna

    2013-08-01

    Purpose: To investigate the tissue dependence in transmission of abscopal radiation signals and their oncogenic consequences in a radiosensitive mouse model and to explore the involvement of gap junction intercellular communication (GJIC) in mediating radiation tumorigenesis in off-target mouse skin. Methods and Materials: Patched1 heterozygous (Ptch1{sup +/−}) mice were irradiated at postnatal day 2 (P2) with 10 Gy of x-rays. Individual lead cylinders were used to protect the anterior two-thirds of the body, whereas the hindmost part was directly exposed to radiation. To test the role of GJICs and their major constituent connexin43 (Cx43), crosses between Ptch1{sup +/−} and Cx43{sup +/−} mice were similarly irradiated. These mouse groups were monitored for their lifetime, and skin basal cell carcinomas (BCCs) were counted and recorded. Early responses to DNA damage - Double Strand Breaks (DSBs) and apoptosis - were also evaluated in shielded and directly irradiated skin areas. Results: We report abscopal tumor induction in the shielded skin of Ptch1{sup +/−} mice after partial-body irradiation. Endpoints were induction of early nodular BCC-like tumors and macroscopic infiltrative BCCs. Abscopal tumorigenesis was significantly modulated by Cx43 status, namely, Cx43 reduction was associated with decreased levels of DNA damage and oncogenesis in out-of-field skin, suggesting a key role of GJIC in transmission of oncogenic radiation signals to unhit skin. Conclusions: Our results further characterize the nature of abscopal responses and the implications they have on pathologic processes in different tissues, including their possible underlying mechanistic bases.

  7. Effects of glycerol on human skin damaged by acute sodium lauryl sulphate treatment.

    PubMed

    Atrux-Tallau, Nicolas; Romagny, Céline; Padois, Karine; Denis, Alain; Haftek, Marek; Falson, Françoise; Pirot, Fabrice; Maibach, Howard I

    2010-08-01

    Glycerol, widely used as humectant, is known to protect against irritants and to accelerate recovery of irritated skin. However, most studies were done with topical formulations (i.e. emulsions) containing glycerol in relatively high amounts, preventing drawing conclusions from direct effects. In this study, acute chemical irritations were performed on the forearm with application of a 10% sodium lauryl sulphate (SLS) aqueous solution under occlusion for 3 h. Then, glycerol aqueous solutions from 1 to 10% were applied under occlusion for 3 h. After elimination of moist excess consecutive to occlusive condition, in ambient air for 15 and 30 min, skin barrier function was investigated by dual measurement of skin hydration and transepidermal water loss (TEWL). Treatments with SLS solution under occlusion significantly increased TEWL and decreased skin hydration as assessed by capacitance measurements. The SLS irritant property was raised by the occlusion and the water barrier function as well as water content appeared impaired. Recovery with glycerol at low doses was remarkable through a mechanism that implies its hygroscopic properties and which is saturable. This precocious effect acts through skin rehydration by enhancing water-holding capacity of stratum corneum that would facilitate the late physiological repair of impaired skin barrier. Thus, glycerol appears to substitute for natural moisturizing factors that have been washed out by the detergent action of SLS, enhancing skin hydration but without restoring skin barrier function as depicted by TEWL values that remained high. Thus, irritant contact dermatitis treated with glycerol application compensate for skin dehydration, favouring physiological process to restore water barrier function of the impaired skin. Empirical use of glycerol added topical formulations onto detergent altered skin was substantiated in the present physicochemical approach.

  8. Intrinsic quantum anomalous Hall effect in the kagome lattice Cs2LiMn3F12

    SciTech Connect

    Xu, Gang; Lian, Biao; Zhang, Shou -Cheng

    2015-10-27

    In a kagome lattice, the time reversal symmetry can be broken by a staggered magnetic flux emerging from ferromagnetic ordering and intrinsic spin-orbit coupling, leading to several well-separated nontrivial Chern bands and intrinsic quantum anomalous Hall effect. Based on this idea and ab initio calculations, we propose the realization of the intrinsic quantum anomalous Hall effect in the single layer Cs2Mn3F12 kagome lattice and on the (001) surface of a Cs2LiMn3F12 single crystal by modifying the carrier coverage on it, where the band gap is around 20 meV. Furthermore, a simplified tight binding model based on the in-plane ddσ antibonding states is constructed to understand the topological band structures of the system.

  9. Discriminating between Z Prime -boson effects and effects of anomalous gauge couplings in the double production of W{sup {+-}} bosons at a linear collider

    SciTech Connect

    Andreev, Vasili V.; Pankov, A. A.

    2013-06-15

    The potential of the International Linear electron-positron Collider (ILC) for seeking, in the annihilation production of W{sup {+-}}-boson pairs, signals induced by new neutral gauge bosons predicted by models belonging to various classes and featuring an extended gauge sector is studied. Limits that will be obtained at ILC for the parameters and masses of Z Prime bosons are compared with present-day and future data from the Large Hadron Collider (LHC). The possibility of discriminating between the effects of Z-Z Prime mixing and signals induced by anomalous gauge couplings (AGC) is demonstrated within theoretically motivated trilinear gauge models involving several free anomalous parameters. It is found that the sensitivity of ILC to the effects of Z-Z Prime mixing in the process e{sup +}e{sup -} {yields} W{sup +}W{sup -} and its ability to discriminate between these two new-physics scenarios, Z Prime and AGC, become substantially higher upon employing polarized initial (e{sup +}e{sup -}) and final (W{sup {+-}}) states.

  10. Anomalous Hall effect and spin-orbit torques in MnGa/IrMn films: Modification from strong spin Hall effect of the antiferromagnet

    NASA Astrophysics Data System (ADS)

    Meng, K. K.; Miao, J.; Xu, X. G.; Wu, Y.; Zhao, X. P.; Zhao, J. H.; Jiang, Y.

    2016-12-01

    We report systematic measurements of anomalous Hall effect (AHE) and spin-orbit torques (SOTs) in MnGa/IrMn films, in which a single L 10-MnGa epitaxial layer reveals obvious orbital two-channel Kondo (2CK) effect. As increasing the thickness of the antiferromagnet IrMn, the strong spin Hall effect (SHE) has gradually suppressed the orbital 2CK effect and modified the AHE of MnGa. A scaling involving multiple competing scattering mechanisms has been used to distinguish different contributions to the modified AHE. Finally, the sizeable SOT in the MnGa/IrMn films induced by the strong SHE of IrMn have been investigated. The IrMn layer also supplies an in-plane exchange bias field and enables nearly field-free magnetization reversal.

  11. The moisturizing effects of glycolipid biosurfactants, mannosylerythritol lipids, on human skin.

    PubMed

    Yamamoto, Shuhei; Morita, Tomotake; Fukuoka, Tokuma; Imura, Tomohiro; Yanagidani, Shusaku; Sogabe, Atsushi; Kitamoto, Dai; Kitagawa, Masaru

    2012-01-01

    Glycolipid biosurfactants, such as mannosylerythritol lipids (MELs), are produced by different yeasts belonging to the genus Pseudozyma and have been attracting much attention as new cosmetic ingredients owing to their unique liquid-crystal-forming and moisturizing properties. In this study, the effects of different MEL derivatives on the skin were evaluated in detail using a three-dimensional cultured human skin model and an in vivo human study. The skin cells were cultured and treated with sodium dodecyl sulfate (SDS), and the effects of different lipids on the SDS-damaged cells were evaluated on the basis of cell viability. Most MEL derivatives efficiently recovered the viability of the cells and showed high recovery rates (over 80%) comparable with that of natural ceramide. It is interesting that the recovery rate with MEL-A prepared from olive oil was significantly higher than that of MEL-A prepared from soybean oil. The water retention properties of MEL-B were further investigated on human forearm skin in a preliminary study. Compared with the control, the aqueous solution of MEL-B (5 wt%) was estimated to considerably increase the stratum corneum water content in the skin. Moreover, perspiration on the skin surface was clearly suppressed by treatment with the MEL-B solution. These results suggest that MELs are likely to exhibit a high moisturizing action, by assisting the barrier function of the skin. Accordingly, the yeast glycolipids have a strong potential as a new ingredient for skin care products.

  12. Numerical simulation of filling a magnetic flux tube with a cold plasma: Anomalous plasma effects

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Leung, W. C.

    1995-01-01

    Large-scale models of plasmaspheric refilling have revealed that during the early stage of the refilling counterstreaming ion beams are a common feature. However, the instability of such ion beams and its effect on refilling remain unexplored. In order to learn the basic effects of ion beam instabilities on refilling, we have performed numerical simulations of the refilling of an artificial magnetic flux tube. (The shape and size of the tube are assumed so that the essential features of the refilling problem are kept in the simulation and at the same time the small scale processes driven by the ion beams are sufficiently resolved.) We have also studied the effect of commonly found equatorially trapped warm and/or hot plasma on the filling of a flux tube with a cold plasma. Three types of simulation runs have been performed.

  13. The effect of venom skin testing on venom RAST titers.

    PubMed

    Green, R L; Levine, M I

    1982-03-01

    Venom RAST titers were measured in 20 insect-sensitive patients before and two to three weeks after skin testing with insect venoms to determine whether venom testing might cause a rise in venom IgE titers. No significant rise in venom-specific RAST titers for honey bee, wasp and yellow jacket venoms was observed.

  14. Skin Cancer, Irradiation, and Sunspots: The Solar Cycle Effect

    PubMed Central

    Zurbenko, Igor

    2014-01-01

    Skin cancer is diagnosed in more than 2 million individuals annually in the United States. It is strongly associated with ultraviolet exposure, with melanoma risk doubling after five or more sunburns. Solar activity, characterized by features such as irradiance and sunspots, undergoes an 11-year solar cycle. This fingerprint frequency accounts for relatively small variation on Earth when compared to other uncorrelated time scales such as daily and seasonal cycles. Kolmogorov-Zurbenko filters, applied to the solar cycle and skin cancer data, separate the components of different time scales to detect weaker long term signals and investigate the relationships between long term trends. Analyses of crosscorrelations reveal epidemiologically consistent latencies between variables which can then be used for regression analysis to calculate a coefficient of influence. This method reveals that strong numerical associations, with correlations >0.5, exist between these small but distinct long term trends in the solar cycle and skin cancer. This improves modeling skin cancer trends on long time scales despite the stronger variation in other time scales and the destructive presence of noise. PMID:25126567

  15. Anomalous effective magnetoconductivity in disordered bipolar semiconductors: Theory and experimental simulation

    NASA Astrophysics Data System (ADS)

    Chaikovsky, Isaak; Alperovich, Leonid; Gurvich, Yuri; Melnikov, Andrey; Biryukov, Sergey

    2002-05-01

    We present the results of measuring transverse conductivity α⊥c of bipolar heterogeneous semiconductors in classical strong magnetic fields. A stochastic distribution of current carriers (electrons and holes) was created by interband illumination through special masks. The main parameters of crystalline p-Si:B placed in liquid He were the concentrations of the main and compensating impurities, 7×1015 and 4×1012 cm-3, respectively; and the mobilities of electrons and holes, 1×106 and 5×104 cm2/V s, respectively. An anomaly in α⊥c was observed: the ratio of α⊥c for heterogeneous and homogeneous samples depended on magnetic field in a nonmonotonic way, i.e., alternation of increasing and decreasing regions of relative α⊥c for H=0-10 kGs and monotonic growth for H=10-40 kGs. To explain this effect, a theory is presented which is a development of the α⊥c theory for heterogeneous semiconductors with one kind of carrier. It is shown that the effect is due to the redistribution of roles of electrons and holes in magnetoconductivity of homogeneous semiconductors. This effect has high sensitivity to degree of disorder and can be used for detection of small irregularities and as a diagnostic of semiconductor purity.

  16. Synergistic effect of low-frequency ultrasound and surfactants on skin permeability.

    PubMed

    Tezel, Ahmet; Sens, Ashley; Tuchscherer, Joe; Mitragotri, Samir

    2002-01-01

    Low-frequency ultrasound (20 kHz) and surfactants have been individually shown to enhance transdermal drug transport. In this study, we investigated the synergistic effect of ultrasound and surfactants on transdermal drug delivery. Surfactants with different head group chemistries including anionic, cationic, and nonionic with varying tail lengths (8-16-carbon atoms) were studied. We found that surfactants possessing anionic and cationic head groups were more potent than those possessing nonionic head groups in increasing skin conductivity in the presence of ultrasound. Furthermore, for surfactants possessing the same head group, those with a 14-carbon tail length were found to be most effective in enhancing skin permeability. The data presented in this report show that ultrasound and surfactants synergistically enhance skin permeability. Two mechanisms are shown to play a role in this synergistic effect. First, ultrasound enhances surfactant delivery (enhanced delivery) into the skin and, second, ultrasound disperses surfactant (enhanced dispersion) within the skin. In general, surfactants that are potent enhancers by themselves are potent enhancers in the presence of ultrasound as well. We performed imaging experiments to assess the effect of ultrasound on delivery of a model permeant, sulforhodamine B, into the skin. These experiments show that ultrasound enhances surfactant delivery and dispersion in the skin.

  17. Clinical effects of an oral supplement rich in antioxidants on skin radiance in women

    PubMed Central

    Dumoulin, Marion; Gaudout, David; Lemaire, Benoit

    2016-01-01

    Background Environmental factors impact the skin aging resulting in decrease of skin radiance. Nutrition and particularly antioxidants could help to fight against skin degradation. Objective The aim of this study was to evaluate the effects of an oral supplement rich in specific antioxidants, SkinAx2TM, on the improvement of the skin radiance in women. Methods The open-label clinical study enrolled 35 women, aged 40–70, with facial dull complexion. Subjects were supplemented orally with a daily dosage of 150 mg of an antioxidant-rich formulation containing superoxide dismutase-rich melon concentrate, grape seed extract rich in monomers of flavanols, vitamin C, and zinc for 8 weeks. Each subject served as her own control. The C.L.B.T.™ test has been used to evaluate facial skin coloring (C), luminosity (L), brightness (B), and transparency (T) involved in skin radiance. Facial skin imperfections have been assessed by clinical assessment. Firmness has been evaluated by clinical assessment and cutometer measurement. Finally, an auto-questionnaire has been carried out in order to evaluate the satisfaction of the subjects concerning different parameters involved in skin radiance and the global efficacy of the supplement. Results Skin “red pink” and “olive” colors were significantly improved after supplementation (P<0.0001). Luminosity was increased by 25.9% (P<0.0001) whereas brightness and transparency were not affected by the supplementation. Facial skin imperfections were significantly reduced after the antioxidant-rich formulation intake (global reduction: −18.0%; P<0.0001). Indeed, dark circles, redness, and spots significantly diminished after oral treatment. Firmness and elasticity have been shown to be improved. Subjects were globally satisfied by the product (82.4%) and have found improvements on their facial skin. Furthermore, 64.7% reported to look better at the end of the supplementation. Conclusion The oral supplement containing the

  18. Evaluation of sunscreen safety by in vitro skin permeation studies: effects of vehicle composition.

    PubMed

    Montenegro, L; Puglisi, G

    2013-01-01

    For sunscreens to be safe and effective, the lowest possible UV-filter percutaneous absorption should be achieved. In this paper, we evaluated in vitro release and permeation through human skin of two UV-filters, octyl methoxycinnammate (OMC) and butyl methoxydibenzoyl methane (BMBM) from six commercial O/W emulsions and we estimated their margin of safety (MoS). OMC and BMBM in vitro release and skin permeation were investigated in Franz-type diffusion cells and permeation data were used to calculate MoS. OMC in vitro skin permeation depended on both its concentration and vehicle composition while BMBM skin permeation depended on its release from the vehicle. MoS values were well beyond the lowest limit accepted for safe products. Although sunscreen skin permeation may depend on many factors, the commercial products investigated are safe under normal "in use" conditions.

  19. Investigation of jewelry powders radiating far-infrared rays and the biological effects on human skin.

    PubMed

    Yoo, B H; Park, C M; Oh, T J; Han, S H; Kang, H H; Chang, I S

    2002-01-01

    Far-infrared rays have certain kinds of effects on the human body, especially on skin, blood circulation, and skin cell vitalizing. Some jewelry powders radiate far-infrared rays. Jade has powerful far-infrared ray radiation, and tourmaline has pyroelectric and piezoelectric properties and radiated far-infrared rays. The jewelry powders (fine powdered jade and tourmaline powders) were screened by far-infrared rays for radiation properties and tested for the effects of far-infrared rays on the human skin by temperature observation using an infrared thermal analyzer.

  20. Anomalous Hall effect in epitaxial ferrimagnetic anti-perovskite Mn{sub 4−x}Dy{sub x}N films

    SciTech Connect

    Meng, M.; Wu, S. X. Zhou, W. Q.; Ren, L. Z.; Wang, Y. J.; Wang, G. L.; Li, S. W.

    2015-08-07

    Anomalous Hall effect (AHE) has been studied for ferrimagnetic antiperovskite Mn{sub 4−x}Dy{sub x}N films grown by molecular-beam epitaxy. The introduction of Dy changes the AHE dramatically, even changes its sign, while the variations in magnetization are negligible. Two sign reversals of the AHE (negative-positive-negative) are ascribed to the variation of charge carriers as a result of Fermi surface reconstruction. We further demonstrate that the AHE current J{sub AH} is dissipationless (independent of the scattering rate), by confirming that anomalous Hall conductivity, σ{sub AH}, is proportional to the carrier density n at 5 K. Our study may provide a route to further utilize antiperovskite manganese nitrides in spintronics.

  1. Hairy skin exposure to VX in vitro: effectiveness of delayed decontamination.

    PubMed

    Rolland, P; Bolzinger, M-A; Cruz, C; Josse, D; Briançon, S

    2013-02-01

    The chemical warfare agents such as VX represent a threat for both military and civilians, which involves an immediate need of effective decontamination systems. Since human scalp is usually unprotected compared to other body regions covered with clothes, it could be a preferential site of exposure in case of terrorist acts. The purpose of this study was to determine if skin decontamination could be efficient when performed more than 1h after exposure. In addition, the impact of hairs in skin contamination was investigated. By using in vitro skin models, we demonstrated that about 75% of the applied quantity of VX was recovered on the skin surface 2h after skin exposition, which means that it is worth decontaminating even if contamination occurred 2h before. The stratum corneum reservoir for VX was quickly established and persistent. In addition, the presence of hairs modified the percutaneous penetration of the nerve agent by binding of VX to hairs. Hair shaft has thus to be taken into account in the decontamination process. Reactive Skin Decontamination Lotion (RSDL) and Fuller's Earth (FE) were active in the skin decontamination 45min post-exposure, but RSDL was more efficient in reducing the amount of VX either in the skin or in the hair.

  2. The effect of skin thickness determined using breast CT on mammographic dosimetry

    SciTech Connect

    Huang Shihying; Boone, John M.; Yang, Kai; Kwan, Alexander L. C.; Packard, Nathan J.

    2008-04-15

    The effect of breast skin thickness on dosimetry in mammography was investigated. Breast computed tomography (CT) acquisition techniques, combined with algorithms designed for determining specific breast metrics, were useful for estimating skin thickness. A radial-geometry edge detection scheme was implemented on coronal reconstructed breast CT (bCT) images to measure the breast skin thickness. Skin thickness of bilateral bCT volume data from 49 women and unilateral bCT volume data from 2 women (10 healthy women and 41 women with BIRADS 4 and 5 diagnoses) was robustly measured with the edge detection scheme. The mean breast skin thickness ({+-}inter-breast standard deviation) was found to be 1.45{+-}0.30 mm. Since most current published normalized glandular dose (D{sub gN}) coefficients are based on the assumption of a 4-mm breast skin thickness, the D{sub gN} values computed with Monte Carlo techniques will increase up to 18% due to the thinner skin layers (e.g., 6-cm 50% glandular breast, 28 kVp Mo-Mo spectrum). The thinner skin dimensions found in this study suggest that the current D{sub gN} values used for mammographic dosimetry lead to a slight underestimate in glandular dose.

  3. High electron mobility, quantum Hall effect and anomalous optical response in atomically thin InSe

    DOE PAGES

    Bandurin, Denis A.; Tyurnina, Anastasia V.; Yu, Geliang L.; ...

    2016-11-21

    A decade of intense research on two-dimensional (2D) atomic crystals has revealed that their properties can differ greatly from those of the parent compound. These differences are governed by changes in the band structure due to quantum confinement and are most profound if the underlying lattice symmetry changes. Here we report a high-quality 2D electron gas in few-layer InSe encapsulated in hexagonal boron nitride under an inert atmosphere. Carrier mobilities are found to exceed 103 cm2 V–1s–1 and 104 cm2 V–1 s–1 at room and liquid-helium temperatures, respectively, allowing the observation of the fully developed quantum Hall effect. The conductionmore » electrons occupy a single 2D subband and have a small effective mass. Photoluminescence spectroscopy reveals that the bandgap increases by more than 0.5 eV with decreasing the thickness from bulk to bilayer InSe. The band-edge optical response vanishes in monolayer InSe, which is attributed to the monolayer's mirror-plane symmetry. As a result, encapsulated 2D InSe expands the family of graphene-like semiconductors and, in terms of quality, is competitive with atomically thin dichalcogenides and black phosphorus.« less

  4. High electron mobility, quantum Hall effect and anomalous optical response in atomically thin InSe.

    PubMed

    Bandurin, Denis A; Tyurnina, Anastasia V; Yu, Geliang L; Mishchenko, Artem; Zólyomi, Viktor; Morozov, Sergey V; Kumar, Roshan Krishna; Gorbachev, Roman V; Kudrynskyi, Zakhar R; Pezzini, Sergio; Kovalyuk, Zakhar D; Zeitler, Uli; Novoselov, Konstantin S; Patanè, Amalia; Eaves, Laurence; Grigorieva, Irina V; Fal'ko, Vladimir I; Geim, Andre K; Cao, Yang

    2017-03-01

    A decade of intense research on two-dimensional (2D) atomic crystals has revealed that their properties can differ greatly from those of the parent compound. These differences are governed by changes in the band structure due to quantum confinement and are most profound if the underlying lattice symmetry changes. Here we report a high-quality 2D electron gas in few-layer InSe encapsulated in hexagonal boron nitride under an inert atmosphere. Carrier mobilities are found to exceed 10(3) cm(2) V(-1) s(-1) and 10(4) cm(2) V(-1) s(-1) at room and liquid-helium temperatures, respectively, allowing the observation of the fully developed quantum Hall effect. The conduction electrons occupy a single 2D subband and have a small effective mass. Photoluminescence spectroscopy reveals that the bandgap increases by more than 0.5 eV with decreasing the thickness from bulk to bilayer InSe. The band-edge optical response vanishes in monolayer InSe, which is attributed to the monolayer's mirror-plane symmetry. Encapsulated 2D InSe expands the family of graphene-like semiconductors and, in terms of quality, is competitive with atomically thin dichalcogenides and black phosphorus.

  5. High electron mobility, quantum Hall effect and anomalous optical response in atomically thin InSe

    SciTech Connect

    Bandurin, Denis A.; Tyurnina, Anastasia V.; Yu, Geliang L.; Mishchenko, Artem; Zólyomi, Viktor; Morozov, Sergey V.; Kumar, Roshan Krishna; Gorbachev, Roman V.; Kudrynskyi, Zakhar R.; Pezzini, Sergio; Kovalyuk, Zakhar D.; Zeitler, Uli; Novoselov, Konstantin S.; Patanè, Amalia; Eaves, Laurence; Grigorieva, Irina V.; Fal'ko, Vladimir I.; Geim, Andre K.; Cao, Yang

    2016-11-21

    A decade of intense research on two-dimensional (2D) atomic crystals has revealed that their properties can differ greatly from those of the parent compound. These differences are governed by changes in the band structure due to quantum confinement and are most profound if the underlying lattice symmetry changes. Here we report a high-quality 2D electron gas in few-layer InSe encapsulated in hexagonal boron nitride under an inert atmosphere. Carrier mobilities are found to exceed 103 cm2 V–1s–1 and 104 cm2 V–1 s–1 at room and liquid-helium temperatures, respectively, allowing the observation of the fully developed quantum Hall effect. The conduction electrons occupy a single 2D subband and have a small effective mass. Photoluminescence spectroscopy reveals that the bandgap increases by more than 0.5 eV with decreasing the thickness from bulk to bilayer InSe. The band-edge optical response vanishes in monolayer InSe, which is attributed to the monolayer's mirror-plane symmetry. As a result, encapsulated 2D InSe expands the family of graphene-like semiconductors and, in terms of quality, is competitive with atomically thin dichalcogenides and black phosphorus.

  6. High electron mobility, quantum Hall effect and anomalous optical response in atomically thin InSe

    NASA Astrophysics Data System (ADS)

    Bandurin, Denis A.; Tyurnina, Anastasia V.; Yu, Geliang L.; Mishchenko, Artem; Zólyomi, Viktor; Morozov, Sergey V.; Kumar, Roshan Krishna; Gorbachev, Roman V.; Kudrynskyi, Zakhar R.; Pezzini, Sergio; Kovalyuk, Zakhar D.; Zeitler, Uli; Novoselov, Konstantin S.; Patanè, Amalia; Eaves, Laurence; Grigorieva, Irina V.; Fal'Ko, Vladimir I.; Geim, Andre K.; Cao, Yang

    2016-11-01

    A decade of intense research on two-dimensional (2D) atomic crystals has revealed that their properties can differ greatly from those of the parent compound. These differences are governed by changes in the band structure due to quantum confinement and are most profound if the underlying lattice symmetry changes. Here we report a high-quality 2D electron gas in few-layer InSe encapsulated in hexagonal boron nitride under an inert atmosphere. Carrier mobilities are found to exceed 103 cm2 V‑1 s‑1 and 104 cm2 V‑1 s‑1 at room and liquid-helium temperatures, respectively, allowing the observation of the fully developed quantum Hall effect. The conduction electrons occupy a single 2D subband and have a small effective mass. Photoluminescence spectroscopy reveals that the bandgap increases by more than 0.5 eV with decreasing the thickness from bulk to bilayer InSe. The band-edge optical response vanishes in monolayer InSe, which is attributed to the monolayer's mirror-plane symmetry. Encapsulated 2D InSe expands the family of graphene-like semiconductors and, in terms of quality, is competitive with atomically thin dichalcogenides and black phosphorus.

  7. Intrinsic quantum spin Hall and anomalous Hall effects in h-Sb/Bi epitaxial growth on a ferromagnetic MnO2 thin film.

    PubMed

    Zhou, Jian; Sun, Qiang; Wang, Qian; Kawazoe, Yoshiyuki; Jena, Puru

    2016-06-07

    Exploring a two-dimensional intrinsic quantum spin Hall state with a large band gap as well as an anomalous Hall state in realizable materials is one of the most fundamental and important goals for future applications in spintronics, valleytronics, and quantum computing. Here, by combining first-principles calculations with a tight-binding model, we predict that Sb or Bi can epitaxially grow on a stable and ferromagnetic MnO2 thin film substrate, forming a flat honeycomb sheet. The flatness of Sb or Bi provides an opportunity for the existence of Dirac points in the Brillouin zone, with its position effectively tuned by surface hydrogenation. The Dirac points in spin up and spin down channels split due to the proximity effects induced by MnO2. In the presence of both intrinsic and Rashba spin-orbit coupling, we find two band gaps exhibiting a large band gap quantum spin Hall state and a nearly quantized anomalous Hall state which can be tuned by adjusting the Fermi level. Our findings provide an efficient way to realize both quantized intrinsic spin Hall conductivity and anomalous Hall conductivity in a single material.

  8. Strong Quantum Size Effects in Pb(111) Thin Films Mediated by Anomalous Friedel Oscillations

    SciTech Connect

    Jia, Yu; Wu, Biao; Li, Chong; Eguiluz, Adolfo G; Weitering, Hanno; Zhang, Zhenyu

    2010-01-01

    Using first-principles calculations within density functional theory, we study Friedel oscillations (FOs) in the electron density at different metal surfaces and their influence on the lattice relaxation and stability of ultrathin metal films.We show that the FOs at the Pb(111) surface decay as 1=x with the distance x from the surface, different from the conventional 1=x2 power law at other metal surfaces. The underlying physical reason for this striking difference is tied to the strong nesting of the two different Fermi sheets along the Pb(111) direction. The interference of the strong FOs emanating from the two surfaces of a Pb(111) film, in turn, not only results in superoscillatory interlayer relaxations around the center of the film, but also determines its stability in the quantum regime. As a simple and generic picture, the present findings also explain why quantum size effects are exceptionally robust in Pb(111) films.

  9. Effect of pore blockage on adsorption isotherms and dynamics: Anomalous adsorption of iodine on activated carbon

    SciTech Connect

    Bhatia, S.K.; Liu, F.; Arvind, G.

    2000-04-18

    Isotherm hysteresis and pore-clocking effects of trapped molecules on adsorption dynamics is studied here, using the iodine-carbon system in the 300--343 K temperature range. It is found that a portion of the iodine is strongly adsorbed, and does not desorb, even over very long time scales, while the remainder adsorbs reversibly as a homogeneous monolayer with a Langmuirian isotherm in mesopores. The strongly adsorbed iodine appears to adsorb in micropores and at the mesopore mouths, hindering uptake of the reversible iodine. The uptake data for the adsorption and desorption dynamics of the reversible part is found to be best explained by means of a pore mouth resistance control mechanism. it is concluded that the dynamics of the adsorption and desorption at the pore mouth is important at early stages of the process.

  10. Chiral Magnetic Effect and Anomalous Transport from Real-Time Lattice Simulations

    SciTech Connect

    Müller, Niklas; Schlichting, Sören; Sharma, Sayantan

    2016-09-30

    Here, we present a first-principles study of anomaly induced transport phenomena by performing real-time lattice simulations with dynamical fermions coupled simultaneously to non-Abelian S U ( N c ) and Abelian U ( 1 ) gauge fields. By investigating the behavior of vector and axial currents during a sphaleron transition in the presence of an external magnetic field, we demonstrate how the interplay of the chiral magnetic and chiral separation effect leads to the formation of a propagating wave. Furthermore, we analyze the dependence of the magnitude of the induced vector current and the propagation of the wave on the amount of explicit chiral symmetry breaking due to finite quark masses.

  11. Chiral Magnetic Effect and Anomalous Transport from Real-Time Lattice Simulations

    DOE PAGES

    Müller, Niklas; Schlichting, Sören; Sharma, Sayantan

    2016-09-30

    Here, we present a first-principles study of anomaly induced transport phenomena by performing real-time lattice simulations with dynamical fermions coupled simultaneously to non-Abelian S U ( N c ) and Abelian U ( 1 ) gauge fields. By investigating the behavior of vector and axial currents during a sphaleron transition in the presence of an external magnetic field, we demonstrate how the interplay of the chiral magnetic and chiral separation effect leads to the formation of a propagating wave. Furthermore, we analyze the dependence of the magnitude of the induced vector current and the propagation of the wave on themore » amount of explicit chiral symmetry breaking due to finite quark masses.« less

  12. Wound tension in rhytidectomy. Effects of skin-flap undermining and superficial musculoaponeurotic system suspension.

    PubMed

    Burgess, L P; Casler, J D; Kryzer, T C

    1993-02-01

    This study was conducted to determine the effects of skin-flap undermining and superficial musculoaponeurotic system (SMAS) suspension on wound-closing tension. Nine sides from five fresh-frozen cadavers were used, with closing tension measured at the two main anchor points, anteriorly (A) and posteriorly (P), with and without SMAS plication for minimal (MIN), intermediate (INT), and maximal (MAX) skin-flap undermining. Results indicated that closing tension was significantly decreased with SMAS plication, both A and P, for all three levels of skin undermining. The average decrease in closing tension with SMAS plication was: A-MIN 191 g, A-INT 95 g, A-MAX 83 g, P-MIN 235 g, P-INT 68 g, and P-MAX 70 g (P < .001 for all). Considering the effect of skin-flap undermining alone, closing tension decreased with wider skin-flap undermining, both with and without SMAS plication. The tension-reducing effect of SMAS plication was decreased with wider skin-flap undermining. Regression analysis determined a second-order exponential curve relating closing tension to skin excision.

  13. Parabens inhibit human skin estrogen sulfotransferase activity: possible link to paraben estrogenic effects.

    PubMed

    Prusakiewicz, Jeffery J; Harville, Heather M; Zhang, Yanhua; Ackermann, Chrisita; Voorman, Richard L

    2007-04-11

    Parabens (p-hydroxybenzoate esters) are a group of widely used preservatives in topically applied cosmetic and pharmaceutical products. Parabens display weak associations with the estrogen receptors in vitro or in cell based models, but do exhibit estrogenic effects in animal models. It is our hypothesis that parabens exert their estrogenic effects, in part, by elevating levels of estrogens through inhibition of estrogen sulfotransferases (SULTs) in skin. We report here the results of a structure-activity-relationship of parabens as inhibitors of estrogen sulfation in human skin cytosolic fractions and normal human epidermal keratinocytes. Similar to reports of paraben estrogenicity and estrogen receptor affinity, the potency of SULT inhibition increased as the paraben ester chain length increased. Butylparaben was found to be the most potent of the parabens in skin cytosol, yielding an IC(50) value of 37+/-5 microM. Butylparaben blocked the skin cytosol sulfation of estradiol and estrone, but not the androgen dehydroepiandrosterone. The parabens were also tested as inhibitors of SULT activity in a cellular system, with normal human epidermal keratinocytes. The potency of butylparaben increased three-fold in these cells relative to the IC(50) value from skin cytosol. Overall, these results suggest chronic topical application of parabens may lead to prolonged estrogenic effects in skin as a result of inhibition of estrogen sulfotransferase activity. Accordingly, the skin anti-aging benefits of many topical cosmetics and pharmaceuticals could be derived, in part, from the estrogenicity of parabens.

  14. Anomalous extracellular diffusion in rat cerebellum.

    PubMed

    Xiao, Fanrong; Hrabe, Jan; Hrabetova, Sabina

    2015-05-05

    Extracellular space (ECS) is a major channel transporting biologically active molecules and drugs in the brain. Diffusion-mediated transport of these substances is hindered by the ECS structure but the microscopic basis of this hindrance is not fully understood. One hypothesis proposes that the hindrance originates in large part from the presence of dead-space (DS) microdomains that can transiently retain diffusing molecules. Because previous theoretical and modeling work reported an initial period of anomalous diffusion in similar environments, we expected that brain regions densely populated by DS microdomains would exhibit anomalous extracellular diffusion. Specifically, we targeted granular layers (GL) of rat and turtle cerebella that are populated with large and geometrically complex glomeruli. The integrative optical imaging (IOI) method was employed to evaluate diffusion of fluorophore-labeled dextran (MW 3000) in GL, and the IOI data analysis was adapted to quantify the anomalous diffusion exponent dw from the IOI records. Diffusion was significantly anomalous in rat GL, where dw reached 4.8. In the geometrically simpler turtle GL, dw was elevated but not robustly anomalous (dw = 2.6). The experimental work was complemented by numerical Monte Carlo simulations of anomalous ECS diffusion in several three-dimensional tissue models containing glomeruli-like structures. It demonstrated that both the duration of transiently anomalous diffusion and the anomalous exponent depend on the size of model glomeruli and the degree of their wrapping. In conclusion, we have found anomalous extracellular diffusion in the GL of rat cerebellum. This finding lends support to the DS microdomain hypothesis. Transiently anomalous diffusion also has a profound effect on the spatiotemporal distribution of molecules released into the ECS, especially at diffusion distances on the order of a few cell diameters, speeding up short-range diffusion-mediated signals in less permeable

  15. Anomalous Extracellular Diffusion in Rat Cerebellum

    PubMed Central

    Xiao, Fanrong; Hrabe, Jan; Hrabetova, Sabina

    2015-01-01

    Extracellular space (ECS) is a major channel transporting biologically active molecules and drugs in the brain. Diffusion-mediated transport of these substances is hindered by the ECS structure but the microscopic basis of this hindrance is not fully understood. One hypothesis proposes that the hindrance originates in large part from the presence of dead-space (DS) microdomains that can transiently retain diffusing molecules. Because previous theoretical and modeling work reported an initial period of anomalous diffusion in similar environments, we expected that brain regions densely populated by DS microdomains would exhibit anomalous extracellular diffusion. Specifically, we targeted granular layers (GL) of rat and turtle cerebella that are populated with large and geometrically complex glomeruli. The integrative optical imaging (IOI) method was employed to evaluate diffusion of fluorophore-labeled dextran (MW 3000) in GL, and the IOI data analysis was adapted to quantify the anomalous diffusion exponent dw from the IOI records. Diffusion was significantly anomalous in rat GL, where dw reached 4.8. In the geometrically simpler turtle GL, dw was elevated but not robustly anomalous (dw = 2.6). The experimental work was complemented by numerical Monte Carlo simulations of anomalous ECS diffusion in several three-dimensional tissue models containing glomeruli-like structures. It demonstrated that both the duration of transiently anomalous diffusion and the anomalous exponent depend on the size of model glomeruli and the degree of their wrapping. In conclusion, we have found anomalous extracellular diffusion in the GL of rat cerebellum. This finding lends support to the DS microdomain hypothesis. Transiently anomalous diffusion also has a profound effect on the spatiotemporal distribution of molecules released into the ECS, especially at diffusion distances on the order of a few cell diameters, speeding up short-range diffusion-mediated signals in less permeable

  16. Observation of anomalous linear photogalvanic effect and its dependence on wavelength in undoped InGaAs/AlGaAs multiple quantum well

    NASA Astrophysics Data System (ADS)

    Zhu, Laipan; Liu, Yu; Gao, Hansong; Qin, Xudong; Li, Yuan; Wu, Qing; Chen, Yonghai

    2014-09-01

    We observed an anomalous linear photogalvanic effect (ALPGE) in undoped InGaAs/AlGaAs multiple quantum well and studied its wavelength dependence in details. This effect is believed to originate from the optical momentum alignment effect and the inhomogeneity of light intensity. We find that the spot location with the maximum ALPGE current is wavelength independent. And the normalized ALPGE current decreasing at smaller wavelengths is attributed to the sharp decrease of the momentum and energy relaxation time. The electrical measurement of the spectra dependence of ALPGE is highly sensitive proving to be an effective method for detecting the momentum anisotropy of photoinduced carriers and band coupling.

  17. Observation of anomalous linear photogalvanic effect and its dependence on wavelength in undoped InGaAs/AlGaAs multiple quantum well

    PubMed Central

    2014-01-01

    We observed an anomalous linear photogalvanic effect (ALPGE) in undoped InGaAs/AlGaAs multiple quantum well and studied its wavelength dependence in details. This effect is believed to originate from the optical momentum alignment effect and the inhomogeneity of light intensity. We find that the spot location with the maximum ALPGE current is wavelength independent. And the normalized ALPGE current decreasing at smaller wavelengths is attributed to the sharp decrease of the momentum and energy relaxation time. The electrical measurement of the spectra dependence of ALPGE is highly sensitive proving to be an effective method for detecting the momentum anisotropy of photoinduced carriers and band coupling. PMID:25258612

  18. Constituents from the roots of Taraxacum platycarpum and their effect on proliferation of human skin fibroblasts.

    PubMed

    Warashina, Tsutomu; Umehara, Kaoru; Miyase, Toshio

    2012-01-01

    A MeOH extract from the roots of Taraxacum platycarpum has shown significant effects on the proliferation of normal human skin fibroblasts. Chemical analysis of the extract resulted in the isolation of 26 compounds, including eight new triterpenes, one new sesquiterpene glycoside, and seventeen known compounds. The structure of each new compound was established using NMR spectroscopy. Some triterpenes had a significant effect on the proliferation of normal human skin fibroblasts.

  19. Anomalous transport effects on switching currents of graphene-based Josephson junctions

    NASA Astrophysics Data System (ADS)

    Guarcello, Claudio; Valenti, Davide; Spagnolo, Bernardo; Pierro, Vincenzo; Filatrella, Giovanni

    2017-03-01

    We explore the effect of noise on the ballistic graphene-based small Josephson junctions in the framework of the resistively and capacitively shunted model. We use the non-sinusoidal current–phase relation specific for graphene layers partially covered by superconducting electrodes. The noise induced escapes from the metastable states, when the external bias current is ramped, given the switching current distribution, i.e. the probability distribution of the passages to finite voltage from the superconducting state as a function of the bias current, that is the information more promptly available in the experiments. We consider a noise source that is a mixture of two different types of processes: a Gaussian contribution to simulate an uncorrelated ordinary thermal bath, and non-Gaussian, α-stable (or Lévy) term, generally associated to non-equilibrium transport phenomena. We find that the analysis of the switching current distribution makes it possible to efficiently detect a non-Gaussian noise component in a Gaussian background.

  20. Anomalous transport effects on switching currents of graphene-based Josephson junctions.

    PubMed

    Guarcello, Claudio; Valenti, Davide; Spagnolo, Bernardo; Pierro, Vincenzo; Filatrella, Giovanni

    2017-03-01

    We explore the effect of noise on the ballistic graphene-based small Josephson junctions in the framework of the resistively and capacitively shunted model. We use the non-sinusoidal current-phase relation specific for graphene layers partially covered by superconducting electrodes. The noise induced escapes from the metastable states, when the external bias current is ramped, given the switching current distribution, i.e. the probability distribution of the passages to finite voltage from the superconducting state as a function of the bias current, that is the information more promptly available in the experiments. We consider a noise source that is a mixture of two different types of processes: a Gaussian contribution to simulate an uncorrelated ordinary thermal bath, and non-Gaussian, α-stable (or Lévy) term, generally associated to non-equilibrium transport phenomena. We find that the analysis of the switching current distribution makes it possible to efficiently detect a non-Gaussian noise component in a Gaussian background.

  1. SnTe field effect transistors and the anomalous electrical response of structural phase transition

    SciTech Connect

    Li, Haitao Zhu, Hao; Yuan, Hui; Li, Qiliang; You, Lin; Kopanski, Joseph J.; Richter, Curt A.; Zhao, Erhai

    2014-07-07

    SnTe is a conventional thermoelectric material and has been newly found to be a topological crystalline insulator. In this work, back-gate SnTe field-effect transistors have been fabricated and fully characterized. The devices exhibit n-type transistor behaviors with excellent current-voltage characteristics and large on/off ratio (>10{sup 6}). The device threshold voltage, conductance, mobility, and subthreshold swing have been studied and compared at different temperatures. It is found that the subthreshold swings as a function of temperature have an apparent response to the SnTe phase transition between cubic and rhombohedral structures at 110 K. The abnormal and rapid increase in subthreshold swing around the phase transition temperature may be due to the soft phonon/structure change which causes the large increase in SnTe dielectric constant. Such an interesting and remarkable electrical response to phase transition at different temperatures makes the small SnTe transistor attractive for various electronic devices.

  2. Cutting fluids. Their use and effects on the skin

    SciTech Connect

    Zugerman, C.

    1986-04-01

    Metalworking fluids are liquids that flow or are sprayed over metal that is being altered mechanically or physically. Cutting fluids tend to be alkaline and are often soap-like. As such they denature keratin, defat the skin, and remove water from it, causing dryness, fissures, and frank eczematization. Cutting oil dermatitis is a difficult problem for the involved worker who must continue to support his family despite the presence of this progressive, pruritic, and painful eruption. 25 references.

  3. Radiation effect in mouse skin: Dose fractionation and wound healing

    SciTech Connect

    Gorodetsky, R.; Mou, X.D.; Fisher, D.R.; Taylor, J.M.; Withers, H.R. )

    1990-05-01

    Radiation induced dermal injury was measured by the gain in the physical strength of healing wounds in mouse skin. A sigmoid dose response for the inhibition of wound healing 14 days after surgery was found for single doses of X rays. The sparing of dermal damage from fractionation of the X-ray dose was quantified in terms of the alpha/beta ratio in the linear-quadratic (LQ) model, at a wide range of doses per fraction reaching as low as about 1 Gy. The fit and the appropriateness of the LQ model for the skin wound healing assay was examined with the use of the Fe-plot in which inverse total dose is plotted versus dose per fraction for wound strength isoeffects. The alpha/beta ratio of the skin was about 2.5 Gy (95% confidence of less than +/- 1 Gy) and was appropriate over a dose range of 1 Gy to about 8 Gy. The low alpha/beta value is typical for a late responding tissue. This assay, therefore, has the advantage of measuring and forecasting late radiation responses of the dermis within a short time after irradiation.

  4. The effect of repeated laser stimuli to ink-marked skin on skin temperature—recommendations for a safe experimental protocol in humans

    PubMed Central

    Madden, Victoria J.; Catley, Mark J.; Grabherr, Luzia; Mazzola, Francesca; Shohag, Mohammad

    2016-01-01

    Background. Nd:YAP laser is widely used to investigate the nociceptive and pain systems, generating perpetual and laser-evoked neurophysiological responses. A major procedural concern for the use of Nd:YAP laser stimuli in experimental research is the risk of skin damage. The absorption of Nd:YAP laser stimuli is greater in darker skin, or in pale skin that has been darkened with ink, prompting some ethics boards to refuse approval to experimenters wishing to track stimulus location by marking the skin with ink. Some research questions, however, require laser stimuli to be delivered at particular locations or within particular zones, a requirement that is very difficult to achieve if marking the skin is not possible. We thoroughly searched the literature for experimental evidence and protocol recommendations for safe delivery of Nd:YAP laser stimuli over marked skin, but found nothing. Methods. We designed an experimental protocol to define safe parameters for the use of Nd:YAP laser stimuli over skin that has been marked with black dots, and used thermal imaging to assess the safety of the procedure at the forearm and the back. Results. Using thermal imaging and repeated laser stimulation to ink-marked skin, we demonstrated that skin temperature did not increase progressively across the course of the experiment, and that the small change in temperature seen at the forearm was reversed during the rest periods between blocks. Furthermore, no participant experienced skin damage due to the procedure. Conclusion. This protocol offers parameters for safe, confident and effective experimentation using repeated Nd:YAP laser on skin marked with ink, thus paving the way for investigations that depend on it. PMID:26793428

  5. Isotopic composition of precipitation in Northern Italy: Reverse effect of anomalous climatic events

    NASA Astrophysics Data System (ADS)

    Longinelli, A.; Anglesio, E.; Flora, O.; Iacumin, P.; Selmo, E.

    2006-10-01

    SummaryA few years ago the first comprehensive map of the isotopic composition of precipitation in Italy was published, based on the results obtained over several years at 77 different locations in Italy. The lack of financial support made it impossible to continue this study extended to the whole country. However, the collection of composite monthly samples continued at 12 locations in Northern Italy. The main purpose was to check the variability through time of the yearly mean isotopic values calculated for some of these stations according to previous data and to add a couple of stations in the western section of Alps, along the Italy-France border for which we had no data. We report here the data obtained for the years 2002-2004. This period is particularly interesting since, during 2003, most of Europe, and particularly Italy, experienced the hottest summer of the last century. In principle, this climatic event should have determined a marked enrichment in heavy isotopes in the annual weighted means for that year. On the contrary, all but one of the collection sites yielded yearly mean isotopic values that were considerably more negative than the mean values calculated for the previous years. This is essentially due to the marked decrease in the yearly amount of precipitation and particularly in that of spring and summer so that the mean weighted yearly isotopic values are heavily affected by the amount of precipitation and the isotopic values of the winter and autumn months. This shift was particularly marked at the collection sites located along the northern slope of the Apennines where a marked "shadow" effect related to westerly air masses moving over the Apennines exists. An important aspect of these data concerns the interpretation of isotopic values of palaeoprecipitation: in the case of palaeo-isotopic changes determined by environmental conditions similar to those reported here, a "normal" interpretation of the data may be misleading.

  6. Nanostructured polymer and lipid carriers for sunscreen. Biological effects and skin permeation.

    PubMed

    Marcato, P D; Caverzan, J; Rossi-Bergmann, B; Pinto, E F; Machado, D; Silva, R A; Justo, G Z; Ferreira, C V; Durán, N

    2011-03-01

    The interest in developing new sunscreens is increasing due to the harmful effects of UV radiation on the skin, such as erythema, accelerated skin ageing (photoageing) and the induction of skin cancer. However, many molecular sunscreens penetrate into the skin causing photoallergies, phototoxic reactions and skin irritation. Thus, the aim of this work was the preparation and characterization of polymeric and solid lipid nanoparticles to act carriers of benzophenone-3 (BZ3), aiming to improve the safety of sunscreen products by increasing the sun protection factor (SPF), decreasing BZ3 skin penetration and decreasing BZ3 concentration in sunscreen formulation. BZ3 was encapsulated in poly(epsilon-caprolactone) (PCL) nanoparticles by the nanoprecipitation method and in solid lipid nanoparticles (SLN) by the hot high pressure homogenization method. The particles were stable for 40 days. The BZ3 encapsulated in PCL nanoparticles was released faster than BZ3 encapsulated in SLN. The sun protection factor increased when BZ3 was encapsulated in both nanostructures. However, BZ3 encapsulated in PCL nanoparticles decreased its skin permeation more than SLN-BZ3. Furthermore, BZ3 encapsulated in SLN did not exhibit cytotoxic or phototoxic effects in human keratinocytes (HaCaT cells) and BABL/c 3T3 fibroblasts, whereas PCL nanoparticles with BZ3 showed phototoxic potential in HaCaT cells. Nevertheless, BZ3 free and encapsulated in PCL nanoparticles or in SLN did not show allergic reactions in mice. Our results suggest that these nanostructures are interesting carriers for sunscreen.

  7. Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling. I. Kinetic equation and anomalous Hall and spin-Hall effects

    NASA Astrophysics Data System (ADS)

    Morawetz, K.

    2015-12-01

    The coupled kinetic equation for density and spin Wigner functions is derived including spin-orbit coupling, electric and magnetic fields, and self-consistent Hartree mean fields suited for SU(2) transport. The interactions are assumed to be with scalar and magnetic impurities as well as scalar and spin-flip potentials among the particles. The spin-orbit interaction is used in a form suitable for solid state physics with Rashba or Dresselhaus coupling, graphene, extrinsic spin-orbit coupling, and effective nuclear matter coupling. The deficiencies of the two-fluid model are worked out consisting of the appearance of an effective in-medium spin precession. The stationary solution of all these systems shows a band splitting controlled by an effective medium-dependent Zeeman field. The self-consistent precession direction is discussed and a cancellation of linear spin-orbit coupling at zero temperature is reported. The precession of spin around this effective direction caused by spin-orbit coupling leads to anomalous charge and spin currents in an electric field. Anomalous Hall conductivity is shown to consist of the known results obtained from the Kubo formula or Berry phases and a symmetric part interpreted as an inverse Hall effect. Analogously the spin-Hall and inverse spin-Hall effects of spin currents are discussed which are present even without magnetic fields showing a spin accumulation triggered by currents. The analytical dynamical expressions for zero temperature are derived and discussed in dependence on the magnetic field and effective magnetizations. The anomalous Hall and spin-Hall effect changes sign at higher than a critical frequency dependent on the relaxation time.

  8. The role of the skin barrier in modulating the effects of common skin microbial species on the inflammation, differentiation and proliferation status of epidermal keratinocytes

    PubMed Central

    2013-01-01

    Background Skin resident microbial species are often thought of either as pathogenic or commensal. However, little is known about the role of the skin barrier in modulating their potential for causing disease. To investigate this question we measured the effects of three microbial species commonly found on the skin (Staphylococcus epidermidis, Staphylococcus aureus, and Propionibacterium acnes) on a reconstructed human epidermal model by either applying the bacteria on the model surface (intact barrier) or adding them to the culture medium (simulating barrier breach). Results When added to the medium, all of the tested species induced inflammatory responses and keratinocyte cell death with species-specific potency. P. acnes and S. epidermidis induced specific alterations in the expression of keratinocyte differentiation and proliferation markers, suggesting a barrier reparation response. S. aureus induced complete keratinocyte cell death. On the contrary, topically applied S. epidermidis and P. acnes caused no inflammatory response even when tested at high concentrations, while topical S. aureus induced a weak reaction. None of the tested species were able to alter the expression of keratinocyte differentiation or expression markers, when applied topically. Conclusions We show that the skin barrier prevents the effects of common skin bacteria on epidermal keratinocyte inflammation, differentiation and proliferation and highlight the importance of skin barrier in defending against the pathogenic effects of common skin bacteria. PMID:24245826

  9. Flavanone silibinin treatment attenuates nitrogen mustard-induced toxic effects in mouse skin

    SciTech Connect

    Jain, Anil K.; Tewari-Singh, Neera; Inturi, Swetha; Kumar, Dileep; Orlicky, David J.; Agarwal, Chapla; White, Carl W.; Agarwal, Rajesh

    2015-05-15

    Currently, there is no effective antidote to prevent skin injuries by sulfur mustard (SM) and nitrogen mustard (NM), which are vesicating agents with potential relevance to chemical warfare, terrorist attacks, or industrial/laboratory accidents. Our earlier report has demonstrated the therapeutic efficacy of silibinin, a natural flavanone, in reversing monofunctional alkylating SM analog 2-chloroethyl ethyl sulfide-induced toxic effects in mouse skin. To translate this effect to a bifunctional alkylating vesicant, herein, efficacy studies were carried out with NM. Topical application of silibinin (1 or 2 mg) 30 min after NM exposure on the dorsal skin of male SKH-1 hairless mice significantly decreased NM-induced toxic lesions at 24, 72 or 120 h post-exposure. Specifically, silibinin treatment resulted in dose-dependent reduction of NM-induced increase in epidermal thickness, dead and denuded epidermis, parakeratosis and microvesication. Higher silibinin dose also caused a 79% and 51%reversal in NM-induced increases in myeloperoxidase activity and COX-2 levels, respectively. Furthermore, silibinin completely prevented NM-induced H2A.X phosphorylation, indicating reversal of DNA damage which could be an oxidative DNA damage as evidenced by high levels of 8-oxodG in NM-exposed mouse skin that was significantly reversed by silibinin. Together, these findings suggest that attenuation of NM-induced skin injury by silibinin is due to its effects on the pathways associated with DNA damage, inflammation, vesication and oxidative stress. In conclusion, results presented here support the optimization of silibinin as an effective treatment of skin injury by vesicants. - Highlights: • Silibinin treatment attenuated nitrogen mustard (NM)-induced skin injury. • Silibinin affects pathways associated with DNA damage, inflammation and vesication. • The efficacy of silibinin could also be associated with oxidative stress. • These results support testing and optimization of

  10. Three loop cusp anomalous dimension in QCD.

    PubMed

    Grozin, Andrey; Henn, Johannes M; Korchemsky, Gregory P; Marquard, Peter

    2015-02-13

    We present the full analytic result for the three loop angle-dependent cusp anomalous dimension in QCD. With this result, infrared divergences of planar scattering processes with massive particles can be predicted to that order. Moreover, we define a closely related quantity in terms of an effective coupling defined by the lightlike cusp anomalous dimension. We find evidence that this quantity is universal for any gauge theory and use this observation to predict the nonplanar n(f)-dependent terms of the four loop cusp anomalous dimension.

  11. Effect of skin hydration on the dynamics of fingertip gripping contact.

    PubMed

    André, T; Lévesque, V; Hayward, V; Lefèvre, P; Thonnard, J-L

    2011-11-07

    The dynamics of fingertip contact manifest themselves in the complex skin movements observed during the transition from a stuck state to a fully developed slip. While investigating this transition, we found that it depended on skin hydration. To quantify this dependency, we asked subjects to slide their index fingertip on a glass surface while keeping the normal component of the interaction force constant with the help of visual feedback. Skin deformation inside the contact region was imaged with an optical apparatus that allowed us to quantify the relative sizes of the slipping and sticking regions. The ratio of the stuck skin area to the total contact area decreased linearly from 1 to 0 when the tangential force component increased from 0 to a maximum. The slope of this relationship was inversely correlated to the normal force component. The skin hydration level dramatically affected the dynamics of the contact encapsulated in the course of evolution from sticking to slipping. The specific effect was to reduce the tendency of a contact to slip, regardless of the variations of the coefficient of friction. Since grips were more unstable under dry skin conditions, our results suggest that the nervous system responds to dry skin by exaggerated grip forces that cannot be simply explained by a change in the coefficient of friction.

  12. Prebiotic effects of almonds and almond skins on intestinal microbiota in healthy adult humans.

    PubMed

    Liu, Zhibin; Lin, Xiuchun; Huang, Guangwei; Zhang, Wen; Rao, Pingfan; Ni, Li

    2014-04-01

    Almonds and almond skins are rich in fiber and other components that have potential prebiotic properties. In this study we investigated the prebiotic effects of almond and almond skin intake in healthy humans. A total of 48 healthy adult volunteers consumed a daily dose of roasted almonds (56 g), almond skins (10 g), or commercial fructooligosaccharides (8 g) (as positive control) for 6 weeks. Fecal samples were collected at defined time points and analyzed for microbiota composition and selected indicators of microbial activity. Different strains of intestinal bacteria had varying degrees of growth sensitivity to almonds or almond skins. Significant increases in the populations of Bifidobacterium spp. and Lactobacillus spp. were observed in fecal samples as a consequence of almond or almond skin supplementation. However, the populations of Escherichia coli did not change significantly, while the growth of the pathogen Clostridum perfringens was significantly repressed. Modification of the intestinal microbiota composition induced changes in bacterial enzyme activities, specifically a significant increase in fecal β-galactosidase activity and decreases in fecal β-glucuronidase, nitroreductase and azoreductase activities. Our observations suggest that almond and almond skin ingestion may lead to an improvement in the intestinal microbiota profile and a modification of the intestinal bacterial activities, which would induce the promotion of health beneficial factors and the inhibition of harmful factors. Thus we believe that almonds and almond skins possess potential prebiotic properties.

  13. Effect of skin hydration on the dynamics of fingertip gripping contact

    PubMed Central

    André, T.; Lévesque, V.; Hayward, V.; Lefèvre, P.; Thonnard, J.-L.

    2011-01-01

    The dynamics of fingertip contact manifest themselves in the complex skin movements observed during the transition from a stuck state to a fully developed slip. While investigating this transition, we found that it depended on skin hydration. To quantify this dependency, we asked subjects to slide their index fingertip on a glass surface while keeping the normal component of the interaction force constant with the help of visual feedback. Skin deformation inside the contact region was imaged with an optical apparatus that allowed us to quantify the relative sizes of the slipping and sticking regions. The ratio of the stuck skin area to the total contact area decreased linearly from 1 to 0 when the tangential force component increased from 0 to a maximum. The slope of this relationship was inversely correlated to the normal force component. The skin hydration level dramatically affected the dynamics of the contact encapsulated in the course of evolution from sticking to slipping. The specific effect was to reduce the tendency of a contact to slip, regardless of the variations of the coefficient of friction. Since grips were more unstable under dry skin conditions, our results suggest that the nervous system responds to dry skin by exaggerated grip forces that cannot be simply explained by a change in the coefficient of friction. PMID:21490002

  14. Effect of microscopic modeling of skin in electrical and thermal analysis of transcranial direct current stimulation

    NASA Astrophysics Data System (ADS)

    Gomez-Tames, Jose; Sugiyama, Yukiya; Laakso, Ilkka; Tanaka, Satoshi; Koyama, Soichiro; Sadato, Norihiro; Hirata, Akimasa

    2016-12-01

    Transcranial direct current stimulation (tDCS) is a neuromodulation scheme where a small current is delivered to the brain via two electrodes attached to the scalp. The electrode design is an important topic, not only as regards efficacy, but also from a safety perspective, as tDCS may be related to skin lesions that are sometimes observed after stimulation. Previous computational models of tDCS have omitted the effects of microscopic structures in the skin, and the different soak conditions of the electrodes, and model validation has been limited. In this study, multiphysics and multiscale analysis are proposed to demonstrate the importance of microscopic modeling of the skin, in order to clarify the effects of the internal electric field, and to examine temperature elevation around the electrodes. This novel microscopic model of the skin layer took into consideration the effect of saline/water penetration in hair follicles and sweat ducts on the field distribution around the electrodes. The temperature elevation in the skin was then computed by solving the bioheat equation. Also, a multiscale model was introduced to account for macroscopic and microscopic tissues of the head and skin, which was validated by measurement of the head resistance during tDCS. As a result, the electric field in the microscopic model of the skin was less localized when the follicles/ducts were filled with saline instead of hair or tap water. Temperature elevation was also lessened with saline, in comparison with other substances. Saline, which may penetrate the hair follicles and sweat ducts, suppressed the field concentration around the electrodes. For conventional magnitudes of current injection, and a head resistance of less than 10 kΩ, the temperature elevation in the skin when using saline-soaked electrodes was low, less than 0.1 °C, and unlikely to cause adverse thermal effects.

  15. Cytotoxic Effects of the Ethanol Bane Skin Extract in Human Prostate Cancer Pc3 Cells

    PubMed Central

    Amiri, Maryam; Kazerouni, Faranak; Namaki, Saeed; Darbandi Tamijani, Hassan; Rahimipour, Hooman; Boroumand, Nasrin; Barghi, Siyamak; Ebrahimi, Nazanin; Gheibi Hayat, Seyed Mohammad

    2016-01-01

    Background: It is extensively supposed that vegetarian diet could affect cancer progress and increase the influence of formal chemotherapy. Objectives: The present study was designed to determine the effect of the ethanol Bane skin extract against chemo resistant prostate cancer PC3 cells. Materials and Methods: PC3 and L929 cells were cultivated and then incubated in the ethanol Bane skin extract with various concentrations of 0.78, 1.5, 3.13, 6.25, 12.5 mg/mL in 3 times 24, 48, 72 hours. Cytotoxic effect of the ethanol Bane skin extract on PC3 and L929 cells was examined by MTT assay after 24, 48, and 72 hours. Morphology of PC3 cells was evaluated by Gimsa staining. Results: The ethanol Bane skin extract inhibited proliferation and caused cell death with IC50 values of 2.8 mg/mL on PC3 cells and the IC50 was 6.1 mg/mL on l929 cells. Morphological changes and apoptotic bodies were observed in PC3 cells faced with the ethanol Bane skin extract by staining with Gimsa. Conclusions: The ethanol Bane skin extract could repress the growth of PC3 cell line. This inhibitory effect of the Bane extract depended on the dose and the time on PC3. The result of this study shows that the ethanol Bane skin extract includes photochemical and inhibitory function against proliferation and inducer of apoptosis in human prostate cancer PC3 cells and also has less cytotoxic effect on l929 than PC3 cells. The ethanol Bane skin extract might be a good candidate for the new herbal anticancer drug. PMID:27482333

  16. Effect of Scutellariae herba extracts in experimental model of skin burns: histological and immunohistochemical assessment.

    PubMed

    Bejenaru, Cornelia; Mogoşanu, George Dan; Bejenaru, Ludovic Everard; BiŢă, Andrei; Bălşeanu, Tudor Adrian; Ionică, Floriana Elvira

    2016-01-01

    The skin burns are an issue of great interest and seriousness in the public health domain, by their destructive features. Natural medicinal products are extensively used from ancient times, in ethnopharmacology, for the treatment of skin injuries (burns, wounds, ulcerations) due to the local modulation of the cellular response, in terms of emollient, demulcent, astringent, anti-inflammatory, antimicrobial, epithelizing, wound-healing, immunomodulatory and antioxidant effects.

  17. Molecular mechanisms of green tea polyphenols with protective effects against skin photoaging.

    PubMed

    Roh, Eunmiri; Kim, Jong-Eun; Kwon, Jung Yeon; Park, Jun Seong; Bode, Ann M; Dong, Zigang; Lee, Ki Won

    2017-05-24

    Whereas green tea has historically been consumed in high quantities in Northeast Asia, its popularity is also increasing in many Western countries. Green tea is an abundant source of plant polyphenols exhibiting numerous effects that are potentially beneficial for human health. Accumulating evidence suggests that green tea polyphenols confer protective effects on the skin against ultraviolet (UV) irradiation-induced acceleration of skin aging, involving antimelanogenic, antiwrinkle, antioxidant, and anti-inflammatory effects as well as prevention of immunosuppression. Melanin pigmentation in the skin is a major defense mechanism against UV irradiation, but pigmentation abnormalities such as melasma, freckles, senile lentigines, and other forms of melanin hyperpigmentation can also cause serious health and aesthetic issues. Furthermore, UV irradiation initiates the degradation of fibrillar collagen and elastic fibers, promoting the process of skin aging through deep wrinkle formation and loss of tissue elasticity. UV irradiation-induced formation of free radicals also contributes to accelerated photoaging. Additionally, immunosuppression caused by UV irradiation plays an important role in photoaging and skin carcinogenesis. In this review, we summarize the current literature regarding the antimelanogenic, antiwrinkle, antioxidant, and immunosuppression preventive mechanisms of green tea polyphenols that have been demonstrated to protect against UV irradiation-stimulated skin photoaging, and gauge the quality of evidence supporting the need for clinical studies using green tea polyphenols as anti-photoaging agents in novel cosmeceuticals.

  18. Effect of chemical enhancers and iontophoresis on thiocolchicoside permeation across rabbit and human skin in vitro.

    PubMed

    Artusi, Mariella; Nicoli, Sara; Colombo, Paolo; Bettini, Ruggero; Sacchi, Antonia; Santi, Patrizia

    2004-10-01

    The aim of this work was to study the permeation of thiocolchicoside across the skin in vitro. The effect of the chemical enhancer lauric acid and the physical technique of iontophoresis was investigated. Permeation experiments were performed in vitro using rabbit ear skin as barrier. The effect of lauric acid at different concentrations (2% and 4%) and of the vehicle (water, ethanol, or ethanol/water) was investigated. The primary effect of lauric acid was on the partitioning parameter, whereas the diffusive parameter did not change significantly. When human epidermis was used, the permeation parameters were generally lower, although not significantly different from rabbit ear skin. The data obtained with full-thickness human skin indicate that, despite the hydrophilic nature of thiocolchicoside, the resistance to drug transport is not limited to the stratum corneum, but that the underlying dermal tissue can also contribute. Iontophoresis enhanced the flux of thiocolchicoside compared with the passive control. The mechanism by which iontophoresis enhanced thiocolchicoside transport across the skin was electroosmosis. The permeation of thiocolchicoside across the skin can be enhanced using chemical or physical penetration enhancers.

  19. Beneficial effects of pro-/antioxidant-based nutraceuticals in the skin rejuvenation techniques.

    PubMed

    de Luca, C; Deeva, I; Mikhal'Chik, E; Korkina, L

    2007-04-15

    Modern technologies of skin rejuvenation include many physical and chemical intervention tools--laser irradiation, oxygen and ozone therapy, chemical peels, plastic surgery operations--affecting by different mechanisms the sensitive physiological free radical/antioxidant balance in the skin. All these interventions induce from mild to severe tissue damage, providing beneficial biochemical stimuli for skin re-epithelization and rejuvenation. Paradoxically, free radical production in the course of tissue inflammation helps to combat free radical damage consequent to the ageing process. We have studied two animal models (experimental burn and trichloracetic peeling), reproducing on the Wistar rat the effects generated by the commonly practiced aesthetic medicine procedures of laser resurfacing and chemical peels, demonstrating that the severe oxidative stress induced both systemically and on skin can be modulated by the oral pre- and post treatment administration of specific nutraceutical formulations. Potent antioxidants (RRR-alpha-tocopherol, coenzyme Q10), enhancing antioxidant defences, coupled with mild pro-oxidants, enhancers of a specific immune defense (soy phospholipids, L-methionine), at the blood and the skin levels, proved in fact to be beneficial in vivo, on the rat, for skin healing, trophism and accelerated re-epithelization. Data obtained allow us to predict the possibility of innovative protocols for dermocosmetology, enabling successful lowering of the risk of permanent adverse effects, and prolonging the duration of the beneficial effects of dermocosmetologic procedures.

  20. Partial wave analysis of scattering with the nonlocal Aharonov-Bohm effect and the anomalous cross section induced by quantum interference

    SciTech Connect

    Lin, D.-H.

    2004-05-01

    Partial wave theory of a three dimensional scattering problem for an arbitrary short range potential and a nonlocal Aharonov-Bohm magnetic flux is established. The scattering process of a 'hard sphere'-like potential and the magnetic flux is examined. An anomalous total cross section is revealed at the specific quantized magnetic flux at low energy which helps explain the composite fermion and boson model in the fractional quantum Hall effect. Since the nonlocal quantum interference of magnetic flux on the charged particles is universal, the nonlocal effect is expected to appear in a quite general potential system and will be useful in understanding some other phenomena in mesoscopic physics.

  1. Clinical studies with disposable diapers containing absorbent gelling materials: evaluation of effects on infant skin condition.

    PubMed

    Campbell, R L; Seymour, J L; Stone, L C; Milligan, M C

    1987-12-01

    Disposable infant diapers with absorbent gelling material (cross-linked sodium polyacrylates) incorporated into the core were clinically evaluated for their effect on infant skin condition. Absorbent gelling materials tightly hold water and provide pH control by a buffering capacity as well as by helping to segregate urine apart from feces. Four clinical studies were conducted with each following a rigid protocol that controlled for variables of diet and age in addition to the diaper material that may influence the development of diaper dermatitis and helped to control for any inherent bias in the study. This allowed for the controlled assessment of skin condition with respect to diaper type. Absorbent gelling material-containing disposable, conventional (100% cellulose core) disposable, and home-laundered cloth diapers were test products. In these studies 1614 infants were initially enrolled with 522 of them assigned to absorbent gelling material disposable, 738 to conventional disposable, and 354 to home-laundered cloth diapers. Objective measurements of skin wetness (transepidermal water loss) and skin pH, as well as double-blind grading of diaper dermatitis, were the measures of skin condition. Absorbent gelling material disposable diapers were associated with significantly reduced skin wetness, closer to normal skin pH, and lower degrees of diaper dermatitis when compared to conventional disposable or home-laundered cloth diapers. The results are consistent with the hypothesis that better control in the diaper area of skin wetness, skin pH, and the prevention of the mixing of urine and feces produces a better diaper environment.

  2. Anomalous diffraction approximation limits

    NASA Astrophysics Data System (ADS)

    Videen, Gorden; Chýlek, Petr

    It has been reported in a recent article [Liu, C., Jonas, P.R., Saunders, C.P.R., 1996. Accuracy of the anomalous diffraction approximation to light scattering by column-like ice crystals. Atmos. Res., 41, pp. 63-69] that the anomalous diffraction approximation (ADA) accuracy does not depend on particle refractive index, but instead is dependent on the particle size parameter. Since this is at odds with previous research, we thought these results warranted further discussion.

  3. Faraday anomalous dispersion optical filters

    NASA Technical Reports Server (NTRS)

    Shay, T. M.; Yin, B.; Alvarez, L. S.

    1993-01-01

    The effect of Faraday anomalous dispersion optical filters on infrared and blue transitions of some alkali atoms is calculated. A composite system is designed to further increase the background noise rejection. The measured results of the solar background rejection and image quality through the filter are presented. The results show that the filter may provide high transmission and high background noise rejection with excellent image quality.

  4. The charmonium dissociation in an ''anomalous wind''

    SciTech Connect

    Sadofyev, Andrey V.; Yin, Yi

    2016-01-11

    We study the charmonium dissociation in a strongly coupled chiral plasma in the presence of magnetic field and axial charge imbalance. This type of plasma carries "anomalous flow" induced by the chiral anomaly and exhibits novel transport phenomena such as chiral magnetic effect. We found that the "anomalous flow" would modify the charmonium color screening length by using the gauge/gravity correspondence. We derive an analytical expression quantifying the "anomalous flow" experienced by a charmonium for a large class of chiral plasma with a gravity dual. We elaborate on the similarity and it qualitative difference between anomalous effects on the charmonium color screening length which are model-dependent and those on the heavy quark drag force which are fixed by the second law of thermodynamics. As a result, we speculate on the possible charmonium dissociation induced by the chiral anomaly in heavy ion collisions.

  5. The charmonium dissociation in an ''anomalous wind''

    DOE PAGES

    Sadofyev, Andrey V.; Yin, Yi

    2016-01-11

    We study the charmonium dissociation in a strongly coupled chiral plasma in the presence of magnetic field and axial charge imbalance. This type of plasma carries "anomalous flow" induced by the chiral anomaly and exhibits novel transport phenomena such as chiral magnetic effect. We found that the "anomalous flow" would modify the charmonium color screening length by using the gauge/gravity correspondence. We derive an analytical expression quantifying the "anomalous flow" experienced by a charmonium for a large class of chiral plasma with a gravity dual. We elaborate on the similarity and it qualitative difference between anomalous effects on the charmoniummore » color screening length which are model-dependent and those on the heavy quark drag force which are fixed by the second law of thermodynamics. As a result, we speculate on the possible charmonium dissociation induced by the chiral anomaly in heavy ion collisions.« less

  6. Time and dose-response effects of honokiol on UVB-induced skin cancer development.

    PubMed

    Guillermo, Ruth F; Chilampalli, Chandeshwari; Zhang, Xiaoying; Zeman, David; Fahmy, Hesham; Dwivedi, Chandradhar

    2012-06-01

    Honokiol has shown chemopreventive effects in chemically-induced and UVB-induced skin cancer in mice. In this investigation, we assessed the time-effects of a topical low dose of honokiol (30 μg), and then the effects of different honokiol doses (30, 45, and 60 μg) on a UVB-induced skin cancer model to find an optimal dose and time for desirable chemopreventive effects. UVB radiation (30 mJ/cm(2), 5 days/week for 25 or 27 weeks) was used to induce skin carcinogenesis in SKH-1 mice. For the time-response experiment 30 μg honokiol in acetone was applied topically to the animals before the UVB exposure (30 min, 1 h, and 2 h) and after the UVB exposure (immediately, 30 min, and 1 h). Control groups were treated with acetone. For the dose-response study, animals were treated topically with acetone or honokiol (30, 45, and 60 μg) one hour before the UVB exposure. In the time-response experiment, honokiol inhibited skin tumor multiplicity by 49-58% while reducing tumor volumes by 70-89%. In the dose-response study, honokiol (30, 45, and 60 μg) significantly decreased skin tumor multiplicity by 36-78% in a dose-dependent manner, while tumor area was reduced by 76-94%. Honokiol (60 μg) significantly reduced tumor incidence by 40% as compared to control group. Honokiol applied in very low doses (30 μg) either before or after UVB radiation shows chemopreventive effects. Honokiol (30, 45, and 60 μg) prevents UVB-induced skin cancer in a dose-dependent manner. Honokiol can be an effective chemopreventive agent against skin cancer.

  7. Effect of Tension and Curvature of Skin on Insertion Characteristics of Microneedle Array

    NASA Astrophysics Data System (ADS)

    Tachikawa, Hiroto; Takano, Naoki; Nishiyabu, Kazuaki; Miki, Norihisa; Ami, Yoshimichi

    Recent MEMS (micro electro mechanical system) fabrication techniques have made it possible to produce painless microneedles precisely enough to be inserted into epidermis layer penetrating the stratum corneum of human skin. This paper presents a testing procedure to evaluate the insertion characteristics of microneedle array using cultured human skin considering the tension and the curvature. First, the biaxial strain applied to the cultured human skin was measured by optical technique with image processing. It was found that almost constant strain could be successfully given within a certain area and that error factors in the experiment except the thickness variation of the cultured skin were negligible. Next, using a microneedle square array for brain machine interface (BMI) application, the effects of biaxial tension and the curvature on insertion characteristics were discussed. Within the above mentioned area with high strain, the needles were successfully inserted.

  8. French Maritime Pine Bark Extract (Pycnogenol®) Effects on Human Skin: Clinical and Molecular Evidence.

    PubMed

    Grether-Beck, Susanne; Marini, Alessandra; Jaenicke, Thomas; Krutmann, Jean

    2016-01-01

    Nutritional strategies to benefit skin health are of growing importance. Current approaches mainly involve nutritional supplements containing antioxidants which were initially designed to protect human skin against ultraviolet radiation-induced damage. Within recent years, however, a growing number of studies suggests that the beneficial effects of these products clearly extend beyond photoprotection. In this review we take the nutritional supplement Pycnogenol®, which is based on an extract prepared from French marine pine bark extract, as an example to illustrate this development. Accordingly, the existing data provide compelling evidence that Pycnogenol® intake does not only provide photoprotection, but may be used to (i) reduce hyperpigmentation of human skin and (ii) improve skin barrier function and extracellular matrix homeostasis.

  9. Synchronization of skin ablation and microjet injection for an effective transdermal drug delivery

    NASA Astrophysics Data System (ADS)

    Jang, Hun-jae; Yeo, Seonggu; Yoh, Jack J.

    2016-04-01

    An Er:YAG laser with 2940-nm wavelength and 150-µs pulse duration was built for the purpose of combined ablation and microjet injection. A shorter pulse duration compared to common erbium lasers in dentistry is desirable for a synchronization of skin ablation and subsequent microjet injection into target skin for transdermal injection of liquid dose. A single laser beam is split into two for an optimal energy of pre-ablation of skin and the residual energy allocated to a microjet ejection. A newly designed injector consists of an L-shaped chamber and a parabolic mirror in a single unit, and the handheld laser is a part of an integrated system requiring no optical fiber. Through various injection tests using the porcine skin, the effectiveness of the new delivery system is herein evaluated.

  10. Fermi surface versus Fermi sea contributions to intrinsic anomalous and spin Hall effects of multiorbital metals in the presence of Coulomb interaction and spin-Coulomb drag

    NASA Astrophysics Data System (ADS)

    Arakawa, Naoya

    2016-06-01

    Anomalous Hall effect (AHE) and spin Hall effect (SHE) are fundamental phenomena, and their potential for application is great. However, we understand the interaction effects unsatisfactorily, and should have clarified issues about the roles of the Fermi sea term and Fermi surface term of the conductivity of the intrinsic AHE or SHE of an interacting multiorbital metal and about the effects of spin-Coulomb drag on the intrinsic SHE. Here, we resolve the first issue and provide the first step about the second issue by developing a general formalism in the linear response theory with appropriate approximations and using analytic arguments. The most striking result is that even without impurities, the Fermi surface term, a non-Berry-curvature term, plays dominant roles at high or slightly low temperatures. In particular, this Fermi surface term causes the temperature dependence of the dc anomalous Hall or spin Hall conductivity due to the interaction-induced quasiparticle damping and the correction of the dc spin Hall conductivity due to the spin-Coulomb drag. Those results revise our understanding of the intrinsic AHE and SHE. We also find that the differences between the dc anomalous Hall and longitudinal conductivities arise from the difference in the dominant multiband excitations. This not only explains why the Fermi sea term such as the Berry-curvature term becomes important in clean and low-temperature case only for interband transports, but also provides the useful principles on treating the electron-electron interaction in an interacting multiorbital metal for general formalism of transport coefficients. Several correspondences between our results and experiments are finally discussed.

  11. Wheelchair cushion effect on skin temperature, heat flux, and relative humidity.

    PubMed

    Stewart, S F; Palmieri, V; Cochran, G V

    1980-05-01

    For patients subject to decubitus ulcers, wheelchair cushions should be prescribed with knowledge of the cushion's effect on the thermal as well as mechanical environment of the skin. To define thermal effects that may be encountered during routine use, tests werr made on 24 commercially available cushions. Skin temperature, heat flux and relative humidity were measured under the ischial tuberosities of a normal 24-year-old man during a 1-hour period of sitting on each cushion. After 1 hour, skin temperatures increased by means of 3.4 C and 2.8 C on foams and viscoelastic foams and there were slight decreases in heat flux as compared with control values in air. On gels, skin temperatures remained constant and heat flux increased, while water "floatation" pads caused a mean skin temperature decreased of 2.7 C along with a marked increase in heat flux. Relative humidity at the skin cushion interface increased by 10.4%, 22.8% and 19.8% on foams, gels and water floatation pads, as compared with room air values. Representative cushions from each of the general types (foam, viscoelastic foam, gel and water floatation) also were subjected to 2-hour tests which indicated the measured parameters continued to change asymptotically.

  12. Acute effects of cigarette smoke exposure on experimental skin flaps

    SciTech Connect

    Nolan, J.; Jenkins, R.A.; Kurihara, K.; Schultz, R.C.

    1985-04-01

    Random vascular patterned caudally based McFarlane-type skin flaps were elevated in groups of Fischer 344 rats. Groups of rats were then acutely exposed on an intermittent basis to smoke generated from well-characterized research filter cigarettes. Previously developed smoke inhalation exposure protocols were employed using a Maddox-ORNL inhalation exposure system. Rats that continued smoke exposure following surgery showed a significantly greater mean percent area of flap necrosis compared with sham-exposed groups or control groups not exposed. The possible pathogenesis of this observation as well as considerations and correlations with chronic human smokers are discussed. Increased risks of flap necrosis by smoking in the perioperative period are suggested by this study.

  13. Effects of radioactive hot particles on pig skin

    SciTech Connect

    Kaurin, D.G.; Baum, J.W.; Schaefer, C.W.

    1997-06-01

    The purpose of these studies was to determine the incidence and severity of lesions resulting from very localized deposition of dose to skin from small (< 0.5 mm) discrete radioactive particles as produced in the work environments of nuclear reactors. Hanford mini-pigs were exposed, both on a slightly off the skin, to localized replicate doses from 0.31 to 64 Gy (averaged over 1 cm{sup 2} at 70 {mu}m depth unless noted otherwise) using Sc-46, Yb-175, Tm-170, and fissioned UC{sub 2} isotopes having maximum beta-particle energies from about 0.3 to 3 MeV. Erythema and scabs (indicating ulceration) were scored for up to 71 days post-irradiation. The responses followed normal cumulative probability distributions, and therefore, no true threshold could be defined. Hence, 10 and 50% scab incidence rates were deduced using probit analyses. The lowest dose which produced 10% incidence was about 1 Gy for Yb-175 (0.5 MeV maximum energy) beta particle exposures, and about 3 to 9 Gy for other isotopes. The histopathology of lesions was determined at several doses. Single exposures to doses as large as 1,790 Gy were also given, and results were observed for up to 144 days post-exposure. Severity of detriment was estimated by analyzing the results in terms of lesion diameter, persistence, and infection. Over 1,100 sites were exposed. Only two exposed sites became infected after doses near 5000 Gy; the lesions healed quickly on treatment. 105 refs., 145 figs., 47 tabs.

  14. Faraday anomalous dispersion optical tuners

    NASA Technical Reports Server (NTRS)

    Wanninger, P.; Valdez, E. C.; Shay, T. M.

    1992-01-01

    Common methods for frequency stabilizing diode lasers systems employ gratings, etalons, optical electric double feedback, atomic resonance, and a Faraday cell with low magnetic field. Our method, the Faraday Anomalous Dispersion Optical Transmitter (FADOT) laser locking, is much simpler than other schemes. The FADOT uses commercial laser diodes with no antireflection coatings, an atomic Faraday cell with a single polarizer, and an output coupler to form a compound cavity. This method is vibration insensitive, thermal expansion effects are minimal, and the system has a frequency pull in range of 443.2 GHz (9A). Our technique is based on the Faraday anomalous dispersion optical filter. This method has potential applications in optical communication, remote sensing, and pumping laser excited optical filters. We present the first theoretical model for the FADOT and compare the calculations to our experimental results.

  15. Skin Dictionary

    MedlinePlus

    ... your skin, hair, and nails Skin dictionary Camp Discovery Good Skin Knowledge lesson plans and activities Video library Find a ... your skin, hair, and nails Skin dictionary Camp Discovery Good Skin Knowledge lesson plans and activities Video library Find a ...

  16. Fabrication and local laser heating of freestanding Ni{sub 80}Fe{sub 20} bridges with Pt contacts displaying anisotropic magnetoresistance and anomalous Nernst effect

    SciTech Connect

    Brandl, F.; Grundler, D.

    2014-04-28

    In spin caloritronics, ferromagnetic samples subject to relatively large in-plane temperature gradients ∇T have turned out to be extremely interesting. We report on a preparation technique that allows us to create freely suspended permalloy/Pt hybrid structures where a scanning laser induces ∇T on the order of a few K/μm. We observe both the anisotropic magnetoresistance at room temperature and the magnetic field dependent anomalous Nernst effect under laser heating. The technique is promising for the realization of device concepts considered in spin caloritronics based on suspended ferromagnetic nanostructures with electrical contacts.

  17. Anomalous Diffraction in Crystallographic Phase Evaluation

    PubMed Central

    Hendrickson, Wayne A.

    2014-01-01

    X-ray diffraction patterns from crystals of biological macromolecules contain sufficient information to define atomic structures, but atomic positions are inextricable without having electron-density images. Diffraction measurements provide amplitudes, but the computation of electron density also requires phases for the diffracted waves. The resonance phenomenon known as anomalous scattering offers a powerful solution to this phase problem. Exploiting scattering resonances from diverse elements, the methods of multiwavelength anomalous diffraction (MAD) and single-wavelength anomalous diffraction (SAD) now predominate for de novo determinations of atomic-level biological structures. This review describes the physical underpinnings of anomalous diffraction methods, the evolution of these methods to their current maturity, the elements, procedures and instrumentation used for effective implementation, and the realm of applications. PMID:24726017

  18. Ductile and Compacted Graphite Iron Casting Skin -- Evaluation, Effect on Fatigue Strength and Elimination

    NASA Astrophysics Data System (ADS)

    Boonmee, Sarum

    Compacted graphite (CG) iron features a good combination of tensile strength, impact resistance, thermal conductivity and damping capacity. This combination makes CG iron a material of choice for various applications, especially for the automobile industry. The mechanical properties of CG iron listed in the standards (i.e. ASTM) are for machined specimens. However, since most iron castings retain the original casting surface (a.k.a. casting skin), the actual performance of the part could be significantly different from that of the machined specimens. Recent studies have shown the negative effect of the casting skin, but little quantification of its effect on mechanical properties is available. Further, the understanding of its mechanism of formation is at best incomplete. In this research, the effect of the casting skin on mechanical properties in CG and ductile irons (DI) is explored. The differences in tensile and fatigue properties between as-cast and machined samples were quantified and correlated to the casting skin features. It was found that the presence of the casting skin was accountable for 9% reduction of tensile strength and up to 32% reduction of fatigue strength (for CG iron with 40% nodularity). Several mechanisms of the casting skin formation are proposed in this research. The formation of ferritic and pearlitic rims is explained by decarburizing/carburizing reactions at the mold/metal interface. Mg depletion and solidification kinetics effect were identified as the formation mechanisms of the graphite degradation. A 2-D thermal diffusion model was formulated based on Mg depletion theory. The model can be used to predict the casting skin thickness when Mg depletion is the dominant mechanism. Furthermore, using the asymmetric Fe-Gr phase diagram, some instances of casting skin formation were explained based on solidification kinetics theory. The experimental microstructural evidence and the theoretical progress were conducive to the development of

  19. Screening for potential hazard effects from four nitramines on human eye and skin.

    PubMed

    Fjellsbø, Lise Marie; Van Rompay, An R; Hooyberghs, Jef; Nelissen, Inge; Dusinska, Maria

    2013-06-01

    Amines have potential to be used in CO2 capture and storage (CCS) technology, but as they can be released into the environment and be degraded into more toxic compounds, such as nitrosamines and nitramines, there have been concerns about their negative impact on human health. We investigated the potential toxic effects from acute exposure to dimethylnitramine (DMA-NO2), methylnitramine (MA-NO2), ethanolnitramine (MEA-NO2) and 2-methyl-2-(nitroamino)-1-propanol (AMP-NO2). The eye irritation, and skin sensitization, irritation and corrosion potential of these substances have been evaluated in vitro using the Bovine Corneal Opacity and Permeability (BCOP) assay, VITOSENS® assay, Reconstructed Human Epidermis (RHE) skin irritation test and Corrositex Skin corrosion test, respectively. Exposure to DMA-NO2 induced a mild eye irritation response, while MA-NO2, MEA-NO2 and AMP-NO2 were shown to be very severe eye irritants. MA-NO2 and MEA-NO2 were tested for skin sensitization and found to be non-sensitizers to the skin. In addition, none of the four test substances was irritant or corrosive to the skin.

  20. The effect of environmental humidity and temperature on skin barrier function and dermatitis.

    PubMed

    Engebretsen, K A; Johansen, J D; Kezic, S; Linneberg, A; Thyssen, J P

    2016-02-01

    Physicians are aware that climatic conditions negatively affect the skin. In particular, people living in equator far countries such as the Northern parts of Europe and North America are exposed to harsh weather during the winter and may experience dry and itchy skin, or deterioration of already existing dermatoses. We searched the literature for studies that evaluated the mechanisms behind this phenomenon. Commonly used meteorological terms such as absolute humidity, relative humidity and dew point are explained. Furthermore, we review the negative effect of low humidity, low temperatures and different seasons on the skin barrier and on the risk of dermatitis. We conclude that low humidity and low temperatures lead to a general decrease in skin barrier function and increased susceptible towards mechanical stress. Since pro-inflammatory cytokines and cortisol are released by keratinocytes, and the number of dermal mast cells increases, the skin also becomes more reactive towards skin irritants and allergens. Collectively, published data show that cold and dry weather increase the prevalence and risk of flares in patients with atopic dermatitis.

  1. Chlorhexidine or povidone-iodine: Which solution is more effective on skin colonization in neonates?

    PubMed Central

    Majidipour, Narges; Abdeyazdan, Zahra; Zargham-Boroujeni, Ali

    2013-01-01

    Background: Infection control should be an integrated part of patient care, especially to ensure safety and survival in hospitalized neonates. Although povidone-iodine (PVP-I) solution has been used as the most common antiseptic in hospitals of Iran, chlorhexidine is currently used in some wards for skin disinfection. However, there is no evidence about the superiority of either antiseptic solution over the other one. This clinical trial carried out in two university hospitals affiliated to Isfahan University of Medical Sciences, Isfahan, Iran, aimed to compare the effects of chlorhexidine and PVP-I solutions on skin bacterial colonization in hospitalized neonates. Materials and Methods: The participants were 98 hospitalized infants. In each infant, one area on the skin was disinfected by chlorhexidine while the contralateral site was disinfected by PVP-I. Skin cultures were taken before and after disinfection. Microorganisms were determined and colony count was performed based on a standard method. The collected data were analyzed using descriptive and inferential statistical methods in SPSS v. 14. Results: The mean of microorganism colony count before and after disinfection by either solution was statistically different (P < 0.001). There was no significant difference between the two groups in terms of mean microorganism colony count before disinfection. However, a significant difference was observed after disinfection. Conclusions: PVP-I is more efficacious than chlorhexidine for skin disinfection. Consequently, it seems better to use PVP-I for skin preparation before invasive procedures. PMID:23983729

  2. Effect of Colorspace Transformation, the Illuminance Component, and Color Modeling on Skin Detection

    SciTech Connect

    Jayaram, S; Schmugge, S; Shin, M C; Tsap, L V

    2004-03-22

    Skin detection is an important preliminary process in human motion analysis. It is commonly performed in three steps: transforming the pixel color to a non-RGB colorspace, dropping the illumination component of skin color, and classifying by modeling the skin color distribution. In this paper, we evaluate the effect of these three steps on the skin detection performance. The importance of this study is a new comprehensive colorspace and color modeling testing methodology that would allow for making the best choices for skin detection. Combinations of nine colorspaces, the presence of the absence of the illuminance component, and the two color modeling approaches are compared. The performance is measured by using a receiver operating characteristic (ROC) curve on a large dataset of 805 images with manual ground truth. The results reveal that (1) the absence of the illuminance component decreases performance, (2) skin color modeling has a greater impact than colorspace transformation, and (3) colorspace transformations can improve performance in certain instances. We found that the best performance was obtained by transforming the pixel color to the SCT, HSI, or CIELAB colorspaces, keeping the illuminance component, and modeling the color with the histogram approach.

  3. Effect of surface topographic features on the optical properties of skin: a phantom study

    NASA Astrophysics Data System (ADS)

    Liu, Guangli; Chen, Jianfeng; Zhao, Zuhua; Zhao, Gang; Dong, Erbao; Chu, Jiaru; Xu, Ronald X.

    2016-10-01

    Tissue-simulating phantoms are used to validate and calibrate optical imaging systems and to understand light transport in biological tissue. Light propagation in a strongly turbid medium such as skin tissue experiences multiple scattering and diffuse reflection from the surface. Surface roughness introduces phase shifts and optical path length differences for light which is scattered within the skin tissue and reflected from the surface. In this paper, we study the effect of mismatched surface roughness on optical measurement and subsequent determination of optical properties of skin tissue. A series of phantoms with controlled surface features and optical properties corresponding to normal human skin are fabricated. The fabrication of polydimethylsiloxane (PDMS) phantoms with known surface roughness follows a standard soft lithography process. Surface roughness of skin-simulating phantoms are measured with Bruker stylus profiler. The diffuse reflectance of the phantom is validated by a UV/VIS spectrophotometer. The results show that surface texture and roughness have considerable influence on the optical characteristics of skin. This study suggests that surface roughness should be considered as an important contributing factor for the determination of tissue optical properties.

  4. Effect of Acupuncture Manipulations at LI4 or LI11 on Blood Flow and Skin Temperature.

    PubMed

    Li, Weihui; Ahn, Andrew

    2016-06-01

    Acupuncture induces physiological changes, and patients have reported warm or cool sensations with "Burning Fire" (BF) or "Penetrating Cool" (PC) manipulations. This study aimed to evaluate whether these techniques had distinct effects on skin temperature and blood flow and to examine whether skin temperature correlated with blood flow. The participants were 25 healthy volunteers, each receiving acupuncture manipulations on points LI4 and LI11 bilaterally. Skin temperatures and blood flow were recorded continuously on both arms. The study found that acupuncture significantly increased skin temperature on the needling arm by 0.3514°C on average, but decreased it on the contralateral arm by 0.2201°C on average. Blood flow decreased significantly in both arms during needling (-3.4% and -5.97% for the ipsilateral and the contralateral sides, respectively), but the changes in skin temperature did not correlate with the changes in blood flow. Furthermore, these changes were not significantly different between acupuncture techniques and acupuncture points. In conclusion, acupuncture changes local skin temperature and blood flow independent of the manipulation technique. Moreover, blood flow may not be affected by the increased temperature on the needling arm. These results help to verify traditional Chinese medicine concepts and may help in establishing standards for acupuncture treatments.

  5. Effects of pressure, cold and gloves on hand skin temperature and manual performance of divers.

    PubMed

    Zander, Joanna; Morrison, James

    2008-09-01

    Cold water immersion and protective gloves are associated with decreased manual performance. Although neoprene gloves slow hand cooling, there is little information on whether they provide sufficient protection when diving in cold water. Nine divers wearing three-fingered neoprene gloves and dry suits were immersed in water at 25 and 4 degrees C, at depths of 0.4 msw (101 kPa altitude adjusted) and 40 msw (497 kPa) in a hyperbaric chamber. Skin temperatures were measured at the fingers, hand, forearm, chest and head. Grip strength, tactile sensitivity and manual dexterity were measured at three time intervals. There was an exponential decay in finger and back of hand skin temperatures with exposure time in 4 degrees C water. Finger and back of hand skin temperatures were lower at 40 msw than at 0.4 msw (P < 0.05). There was no effect of pressure or temperature on grip strength. Tactile sensitivity decreased linearly with finger skin temperature at both pressures. Manual dexterity was not affected by finger skin temperature at 0.4 msw, but decreased with fall in finger skin temperature at 40 msw. Results show that neoprene gloves do not provide adequate thermal protection in 4 degrees C water and that impairment of manual performance is dependent on the type of task, depth and exposure time.

  6. Childhood exposure to ultraviolet radiation and harmful skin effects: Epidemiological evidence

    PubMed Central

    Green, Adèle C.; Wallingford, Sarah C.; McBride, Penelope

    2012-01-01

    We review the general amount and patterns of exposure to solar ultraviolet (UV) radiation that children and teenagers experience and the spectrum of UV-related skin damage that can occur as a result. Data about the amount of solar UV received by children and teenagers are relatively few but suggest that around 40–50% of total UV to age 60 occurs before age 20. Among white children, those with the palest complexions suffer the most damage. Comparisons of prevalence and incidence of outcomes in children and teenagers sharing common ancestry, but living at different latitudes, show that prevalence rates of photoaging and melanocytic naevi are higher in Australian compared with British children, and similarly for melanoma. Genetic risk for the majority of the melanomas in teens is a function of genes controlling naevus propensity and pigmentation in the skin. High numbers of naevi and freckles, red hair, blue eyes, inability to tan, as well as a family history are the primary determinants of melanoma among adolescents. Beyond the signs of skin damage seen in children are the latent effects observed later in adulthood. Childhood is believed to be a susceptible window for long-term harmful effects of UV, as evidenced by clear differences in skin cancer risk between child and adult migrants from high to low latitudes. Effective UV radiation protection from childhood is necessary to control both immediate and long-term harmful effects on children’s skin. PMID:21907230

  7. Large power factor and anomalous Hall effect and their correlation with observed linear magneto resistance in Co-doped Bi2Se3 3D topological insulator.

    PubMed

    Singh, Rahul; Shukla, K K; Kumar, A; Okram, G S; Singh, D; Ganeshan, V; Lakhani, Archana; Ghosh, A K; Chatterjee, Sandip

    2016-09-21

    Magnetoresistance (MR), thermo power, magnetization and Hall effect measurements have been performed on Co-doped Bi2Se3 topological insulators. The undoped sample shows that the maximum MR as a destructive interference due to a π-Berry phase leads to a decrease of MR. As the Co is doped, the linearity in MR is increased. The observed MR of Bi2Se3 can be explained with the classical model. The low temperature MR behavior of Co doped samples cannot be explained with the same model, but can be explained with the quantum linear MR model. Magnetization behavior indicates the establishment of ferromagnetic ordering with Co doping. Hall effect data also supports the establishment of ferromagnetic ordering in Co-doped Bi2Se3 samples by showing the anomalous Hall effect. Furthermore, when spectral weight suppression is insignificant, Bi2Se3 behaves as a dilute magnetic semiconductor. Moreover, the maximum power factor is observed when time reversal symmetry (TRS) is maintained. As the TRS is broken the power factor value is decreased, which indicates that with the rise of Dirac cone above the Fermi level the anomalous Hall effect and linearity in MR increase and the power factor decreases.

  8. Effect of diaper cream and wet wipes on skin barrier properties in infants: a prospective randomized controlled trial.

    PubMed

    Garcia Bartels, Natalie; Lünnemann, Lena; Stroux, Andrea; Kottner, Jan; Serrano, José; Blume-Peytavi, Ulrike

    2014-01-01

    The effect of different diaper care procedures on skin barrier function in infants has been minimally investigated and may be assessed using objective methods. In a single-center, prospective trial, 89 healthy 9-month-old infants (±8 wks) were randomly assigned to three diaper care regimens: group I used water-moistened washcloths at diaper changes (n = 30), group II additionally applied diaper cream twice daily (n = 28), and group III used wet wipes and diaper cream twice daily (n = 31). Transepidermal water loss (TEWL), skin hydration (SCH), skin pH, interleukin 1α (IL-1α) levels, and microbiologic colonization were measured in diapered skin (upper outer quadrant of the buttocks), nondiapered skin (upper leg), and if diaper dermatitis (DD) occurred, using the most affected skin area at day 1 and weeks 4 and 8. Skin condition was assessed utilizing a neonatal skin condition score and diaper rash grade. On diapered skin, SCH decreased in groups II and III, whereas TEWL values were reduced in group II only. Skin pH increased in groups II and III. In general, SCH, skin pH, and IL-1α levels were higher in healthy diapered skin than in nondiapered skin. The incidence and course of DD was comparable in all groups. Areas with DD had greater TEWL and skin pH than unaffected skin areas. Infants who received diaper cream had lower SCH and TEWL and higher pH levels in the diapered area than on nondiapered skin. No correlation with the occurrence of DD was found.

  9. Effects of Cosmetic Formulations Containing Hydroxyacids on Sun-Exposed Skin: Current Applications and Future Developments

    PubMed Central

    Kornhauser, Andrija; Coelho, Sergio G.; Hearing, Vincent J.

    2012-01-01

    This paper describes recent data on the effects of various skin formulations containing hydroxyacids (HAs) and related products on sun-exposed skin. The most frequently used classes of these products, such as α- and β-hydroxyacids, polyhydroxy acids, and bionic acids, are reviewed, and their application in cosmetic formulations is described. Special emphasis is devoted to the safety evaluation of these formulations, particularly on the effects of their prolonged use on sun-exposed skin. We also discuss the important contribution of cosmetic vehicles in these types of studies. Data on the effects of HAs on melanogenesis and tanning are also included. Up-to-date methods and techniques used in those explorations, as well as selected future developments in the cosmetic area, are presented. PMID:22675344

  10. Effects of cosmetic formulations containing hydroxyacids on sun-exposed skin: current applications and future developments.

    PubMed

    Kornhauser, Andrija; Coelho, Sergio G; Hearing, Vincent J

    2012-01-01

    This paper describes recent data on the effects of various skin formulations containing hydroxyacids (HAs) and related products on sun-exposed skin. The most frequently used classes of these products, such as α- and β-hydroxyacids, polyhydroxy acids, and bionic acids, are reviewed, and their application in cosmetic formulations is described. Special emphasis is devoted to the safety evaluation of these formulations, particularly on the effects of their prolonged use on sun-exposed skin. We also discuss the important contribution of cosmetic vehicles in these types of studies. Data on the effects of HAs on melanogenesis and tanning are also included. Up-to-date methods and techniques used in those explorations, as well as selected future developments in the cosmetic area, are presented.

  11. Skin effect mitigation in laser processed multi-walled carbon nanotube/copper conductors

    SciTech Connect

    Keramatnejad, K.; Zhou, Y. S.; Gao, Y.; Rabiee Golgir, H.; Wang, M.; Lu, Y. F.; Jiang, L.; Silvain, J.-F.

    2015-10-21

    In this study, laser-processed multi-walled carbon nanotube (MWCNT)/Cu conductors are introduced as potential passive components to mitigate the skin effect of Cu at high frequencies (0–10 MHz). Suppressed skin effect is observed in the MWCNT/Cu conductors compared to primitive Cu. At an AC frequency of 10 MHz, a maximum AC resistance reduction of 94% was observed in a MWCNT/Cu conductor after being irradiated at a laser power density of 189 W/cm{sup 2}. The reduced skin effect in the MWCNT/Cu conductors is ascribed to the presence of MWCNT channels which are insensitive to AC frequencies. The laser irradiation process is observed to play a crucial role in reducing contact resistance at the MWCNT-Cu interfaces, removing impurities in MWCNTs, and densifying MWCNT films.

  12. Effect of mud penetration on borehole skin properties

    NASA Astrophysics Data System (ADS)

    Abboud, Nelly M.; Corapcioglu, M. Yavuz

    1993-08-01

    Clay particles in drilling muds can form a filter cake (skin) on the walls of the well and migrate into the adjacent formation. In general, filter cakes are formed when a liquid phase containing solid particles is forced through a pervious surface which allows liquid transport, while retaining solid particles. Following a literature survey, the governing equations for the concentration of suspended solid particles in the pore fluid, cake permeability, and solid velocity are obtained by considering the mass balance equations for the fluid phase and suspended and captured solid particles. The capture mechanism is represented by a kinetic equation with rate constants for particle trapping and cake erosion. Numerical solutions for the cake permeability, cake resistance, solid particle velocity (cake compression rate), and concentration of suspended particles are obtained by utilizing experimentally available porosity and pressure variations along the dimensionless cake thickness. The results compared for a simplified experimental case, show excellent match. A sensitivity analysis shows that cake permeability and cake resistance are more sensitive to the rate constant of cake erosion than they are to the rate constant of particle capture. It was also determined that the permeability has larger values along the entire cake thickness when the rate constant of particle capture is zero in comparison to values obtained with a nonzero rate constant. Cake permeability is small when the rate constant of cake erosion is large.

  13. Effects of Turmeric (Curcuma longa) on Skin Health: A Systematic Review of the Clinical Evidence.

    PubMed

    Vaughn, Alexandra R; Branum, Amy; Sivamani, Raja K

    2016-08-01

    Turmeric (Curcuma longa), a commonly used spice throughout the world, has been shown to exhibit antiinflammatory, antimicrobial, antioxidant, and anti-neoplastic properties. Growing evidence shows that an active component of turmeric, curcumin, may be used medically to treat a variety of dermatologic diseases. This systematic review was conducted to examine the evidence for the use of both topical and ingested turmeric/curcumin to modulate skin health and function. The PubMed and Embase databases were systematically searched for clinical studies involving humans that examined the relationship between products containing turmeric, curcumin, and skin health. A total of 234 articles were uncovered, and a total of 18 studies met inclusion criteria. Nine studies evaluated the effects of ingestion, eight studies evaluated the effects of topical, and one study evaluated the effects of both ingested and topical application of turmeric/curcumin. Skin conditions examined include acne, alopecia, atopic dermatitis, facial photoaging, oral lichen planus, pruritus, psoriasis, radiodermatitis, and vitiligo. Ten studies noted statistically significant improvement in skin disease severity in the turmeric/curcumin treatment groups compared with control groups. Overall, there is early evidence that turmeric/curcumin products and supplements, both oral and topical, may provide therapeutic benefits for skin health. However, currently published studies are limited and further studies will be essential to better evaluate efficacy and the mechanisms involved. Copyright © 2016 John Wiley & Sons, Ltd.

  14. The effect of the iBEAM Evo carbon fiber tabletop on skin sparing.

    PubMed

    Simpson, John B; Godwin, Guy A

    2011-01-01

    Replicating the attenuation properties of the treatment tabletop are of primary importance for accurate treatment planning; however, the effect of the tabletop on the skin-sparing properties of x-rays can be overlooked. Under some conditions, the reaction of skin to the radiation can be so serious as to be the dose-limiting organ for radiotherapy treatment. Hence, an understanding of the magnitude of the reduction in skin sparing is important. Because of the development of image-guided radiotherapy, modern tabletops have been developed without the use of metal supports that otherwise provided the necessary level of rigidity. Rigidity is instead provided by compressed foam within a carbon-fiber shell, which, although it provides artefact-free imaging and high levels of rigidity, has an adverse affect on the dose in the build-up region. Representative of this type is the iBEAM evo tabletop, whose effect on the skin dose was determined at 6-MV, 10-MV, and 18-MV x-rays. Skin dose was found to increase by 60-70% owing to the tabletop, with the effect increasing with field size and decreasing with energy. By considering an endpoint of erythema, a radiobiological advantage of selecting 10 MV over 6 MV for applicable treatments was demonstrated.

  15. Functional behavior of the anomalous magnetic relaxation observed in melt-textured YBa2Cu3O7-δ samples showing the paramagnetic Meissner effect

    NASA Astrophysics Data System (ADS)

    Dias, F. T.; Vieira, V. N.; Garcia, E. L.; Wolff-Fabris, F.; Kampert, E.; Gouvêa, C. P.; Schaf, J.; Obradors, X.; Puig, T.; Roa, J. J.

    2016-10-01

    We have studied the functional behavior of the field-cooled (FC) magnetic relaxation observed in melt-textured YBa2Cu3O7-δ (Y123) samples with 30 wt% of Y2Ba1Cu1O5 (Y211) phase, in order to investigate anomalous paramagnetic moments observed during the experiments. FC magnetic relaxation experiments were performed under controlled conditions, such as cooling rate and temperature. Magnetic fields up to 5T were applied parallel to the ab plane and along the c-axis. Our results are associated with the paramagnetic Meissner effect (PME), characterized by positive moments during FC experiments, and related to the magnetic flux compression into the samples. After different attempts our experimental data could be adequately fitted by an exponential decay function with different relaxation times. We discuss our results suggesting the existence of different and preferential flux dynamics governing the anomalous FC paramagnetic relaxation in different time intervals. This work is one of the first attempts to interpret this controversial effect in a simple analysis of the pinning mechanisms and flux dynamics acting during the time evolution of the magnetic moment. However, the results may be useful to develop models to explain this interesting and still misunderstood feature of the paramagnetic Meissner effect.

  16. Protective effects of black rice bran against chemically-induced inflammation of mouse skin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated the inhibitory effects of black rice (cv. LK1-3-6-12-1-1) bran against 12-O-tetradecanolylphorbol-13-acetate (TPA)-induced skin edema and 2,4-dinitroflurobenzene (DNFB)-induced allergic contact dermatitis (ACD) in inflammatory mouse models. We also determined the effects of the bran...

  17. Flavanone silibinin treatment attenuates nitrogen mustard-induced toxic effects in mouse skin.

    PubMed

    Jain, Anil K; Tewari-Singh, Neera; Inturi, Swetha; Kumar, Dileep; Orlicky, David J; Agarwal, Chapla; White, Carl W; Agarwal, Rajesh

    2015-05-15

    Currently, there is no effective antidote to prevent skin injuries by sulfur mustard (SM) and nitrogen mustard (NM), which are vesicating agents with potential relevance to chemical warfare, terrorist attacks, or industrial/laboratory accidents. Our earlier report has demonstrated the therapeutic efficacy of silibinin, a natural flavanone, in reversing monofunctional alkylating SM analog 2-chloroethyl ethyl sulfide-induced toxic effects in mouse skin. To translate this effect to a bifunctional alkylating vesicant, herein, efficacy studies were carried out with NM. Topical application of silibinin (1 or 2mg) 30 min after NM exposure on the dorsal skin of male SKH-1 hairless mice significantly decreased NM-induced toxic lesions at 24, 72 or 120 h post-exposure. Specifically, silibinin treatment resulted in dose-dependent reduction of NM-induced increase in epidermal thickness, dead and denuded epidermis, parakeratosis and microvesication. Higher silibinin dose also caused a 79% and 51%reversal in NM-induced increases in myeloperoxidase activity and COX-2 levels, respectively. Furthermore, silibinin completely prevented NM-induced H2A.X phosphorylation, indicating reversal of DNA damage which could be an oxidative DNA damage as evidenced by high levels of 8-oxodG in NM-exposed mouse skin that was significantly reversed by silibinin. Together, these findings suggest that attenuation of NM-induced skin injury by silibinin is due to its effects on the pathways associated with DNA damage, inflammation, vesication and oxidative stress. In conclusion, results presented here support the optimization of silibinin as an effective treatment of skin injury by vesicants.

  18. Flavanone silibinin treatment attenuates nitrogen mustard-induced toxic effects in mouse skin

    PubMed Central

    Jain, Anil K; Tewari-Singh, Neera; Inturi, Swetha; Kumar, Dileep; Orlicky, David J; Agarwal, Chapla; White, Carl W; Agarwal, Rajesh

    2015-01-01

    Currently, there is no effective antidote to prevent skin injuries by sulfur mustard (SM) and nitrogen mustard (NM), which are vesicating agents with potential relevance to chemical warfare, terrorist attacks, or industrial/laboratory accidents. Our earlier report has demonstrated the therapeutic efficacy of silibinin, a natural flavanone, in reversing monofunctional alkylating SM analog 2-chloroethyl ethyl sulfide-induced toxic effects in mouse skin. To translate this effect to a bifunctional alkylating vesicant, herein, efficacy studies were carried out with NM. Topical application of silibinin (1 or 2 mg) 30 min after NM exposure on the dorsal skin of male SKH-1 hairless mice significantly decreased NM-induced toxic lesions at 24, 72 or 120 h post-exposure. Specifically, silibinin treatment resulted in dose-dependent reduction of NM-induced increase in epidermal thickness, dead and denuded epidermis, parakeratosis and microvesication. Higher silibinin dose also caused a 79% and 51% reversal in NM-induced increases in myeloperoxidase activity and COX-2 levels, respectively. Furthermore, silibinin completely prevented NM-induced H2A.X phosphorylation, indicating reversal of DNA damage which could be an oxidative DNA damage as evidenced by high levels of 8-oxodG in NM-exposed mouse skin that was significantly reversed by silibinin. Together, these findings suggest that attenuation of NM-induced skin injury by silibinin is due to its effects on the pathways associated with DNA damage, inflammation, vesication and oxidative stress. In conclusion, results presented here support the optimization of silibinin as an effective treatment of skin injury by vesicants. PMID:25791923

  19. Transcriptomic analysis of bottlenose dolphin (Tursiops truncatus) skin biopsies to assess the effects of emerging contaminants.

    PubMed

    Lunardi, Denise; Abelli, Luigi; Panti, Cristina; Marsili, Letizia; Fossi, Maria Cristina; Mancia, Annalaura

    2016-03-01

    Chemicals discovered in water at levels that may be significantly different than expected are referred to as contaminants of emerging concern (CECs) because the risk to environmental health posed by their occurrence/frequency is still unknown. The worldwide distributed compounds perfluorooctanoic acid (PFOA) and bisphenol A (BPA) may fall into this category due to effects on endocrine receptors. We applied an ex vivo assay using small slices of bioptic skin from the bottlenose dolphin, Tursiops truncatus, cultured and treated for 24 h with different PFOA or BPA concentrations to analyze global gene expression. RNA was labeled and hybridized to a species-specific oligomicroarray. The skin transcriptome held information on the contaminant exposure, potentially predictive about long-term effects on health, being the genes affected involved in immunity modulation, response to stress, lipid homeostasis, and development. The transcriptomic signature of dolphin skin could be therefore relevant as classifier for a specific contaminant.

  20. Iatrogenic effects of photoprotection recommendations on skin cancer development, vitamin D levels, and general health.

    PubMed

    Reddy, Kavitha K; Gilchrest, Barbara A

    2011-01-01

    Ultraviolet (UV) radiation is an established carcinogen that causes skin cancers and other cutaneous photodamage. Vitamin D is produced in the skin after UV exposure and may also be obtained from dietary and supplemental sources. The effect of recommendations for UV protection, as well as for very large vitamin D supplements, and possible adverse effects of both are explored. Current evidence supports the conclusion that protection from UV radiation reduces the incidence of skin cancers and photodamage, but generally does not compromise vitamin D status or lead to iatrogenic disease. Conversely, risks of maintaining very high vitamin D levels have not been adequately studied. Vitamin D obtained from diet and supplements is functionally identical to that produced after UV exposure, and is a more reliable and quantifiable source of the vitamin.

  1. Leucine supplementation has an anabolic effect on proteins in rabbit skin wound and muscle.

    PubMed

    Zhang, Xiao-Jun; Chinkes, David L; Wolfe, Robert R

    2004-12-01

    We investigated the effect of leucine supplementation on protein metabolism in skin wounds and muscle in anesthetized rabbits. l-[ring-(13)C(6)]phenylalanine was infused on d 7 after the ear was scalded, and the scalded ear and uninjured hindlimb were used as arteriovenous units to reflect protein kinetics in skin wounds and muscle. In comparison with a commercially available amino acid solution (10% Travasol), isonitrogenous [1638 micromol/(kg . h)] infusion of the amino acid solution with supplemental leucine to account for 35% of total nitrogen increased the net phenylalanine balance (P < 0.05) in the skin wound and muscle from -6.7 +/- 6.1 to 0.9 +/- 1.4 and from -4.4 +/- 2.4 to -1.0 +/- 0.4 micromol/(100 g . h), respectively. Infusion of leucine alone did not significantly improve the net phenylalanine balance in either skin wounds [-4.0 +/- 4.6 micromol/(100 g . h)] or muscle [-2.7 +/- 0.7 micromol/(100 g . h)]. We conclude that leucine supplementation had an anabolic effect on proteins in skin wounds and muscle, provided that adequate additional amino acids were also available.

  2. Zinc pyrithione in alcohol-based products for skin antisepsis: persistence of antimicrobial effects.

    PubMed

    Guthery, Eugene; Seal, Lawton A; Anderson, Edward L

    2005-02-01

    Alcohol-based products for skin antisepsis have a long history of safety and efficacy in the United States and abroad. However, alcohol alone lacks the required antimicrobial persistence to provide for the sustained periods of skin antisepsis desired in the clinical environment. Therefore, alcohol-based products must have a preservative agent such as iodine/iodophor compounds, chlorhexidine gluconate, or zinc pyrithione, to extend its antimicrobial effects. Iodine, iodophors, and chlorhexidine gluconate are well-characterized antimicrobials and preservatives. The thrust of our effort was to examine the characteristics of the lesser-known zinc pyrithione and to evaluate its utility as a preservative in the formulation of alcohol-based products for skin antisepsis. This work includes a literature review of current zinc pyrithione applications in drugs and cosmetics, a safety and toxicity evaluation, consideration of the proposed mechanisms of antimicrobial action, in vitro and in vivo efficacy data, and a discussion of the mechanisms that confer the desired antimicrobial persistence. In addition, alcohol-based, zinc pyrithione-preserved, commercially available products of skin antisepsis are compared with other commercially available antimicrobials used for skin antisepsis and with additional alcohol-based products with different preservatives. The authors' conclusion is that zinc pyrithione is not only a safe and effective antimicrobial but that its use in certain alcohol-based formulations results in antimicrobial efficacy exceeding that of iodine and chlorhexidine gluconate.

  3. Non-thermal influences on the control of skin blood flow have minimal effects on heat transfer during exercise.

    PubMed Central

    Nadel, E. R.

    1986-01-01

    During exercise, circulatory reflexes ensure that the cardiac output is sufficiently elevated to meet the oxygen delivery requirements of the contracting skeletal muscles and the heat delivery requirements of the body to the skin. The latter requirements are met by increasing skin blood flow. These increases are largely driven by elevations in the body temperatures, although non-thermal effects on the control of skin blood flow occur in certain conditions. These effects are largely the consequence of high and/or low baroreflex stimulation. Even in the face of such non-thermal effects, which occur during exercise in the heat, the body's requirements for heat transfer from core to skin are largely met by the increased skin blood flow. Thus, non-thermal effects on the control of skin blood flow are relatively unimportant in the body's overall regulatory response to exercise. PMID:3751137

  4. Anomalous law of cooling

    NASA Astrophysics Data System (ADS)

    Lapas, Luciano C.; Ferreira, Rogelma M. S.; Rubí, J. Miguel; Oliveira, Fernando A.

    2015-03-01

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  5. Anomalous law of cooling.

    PubMed

    Lapas, Luciano C; Ferreira, Rogelma M S; Rubí, J Miguel; Oliveira, Fernando A

    2015-03-14

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  6. Anomalous law of cooling

    SciTech Connect

    Lapas, Luciano C.; Ferreira, Rogelma M. S.; Rubí, J. Miguel; Oliveira, Fernando A.

    2015-03-14

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton’s law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  7. Effects of Locally Applied Glycerol and Xylitol on the Hydration, Barrier Function and Morphological Parameters of the Skin.

    PubMed

    Korponyai, Csilla; Szél, Edit; Behány, Zoltán; Varga, Erika; Mohos, Gábor; Dura, Ágnes; Dikstein, Shabtay; Kemény, Lajos; Erős, Gábor

    2017-02-08

    Glycerol and xylitol hydrate the skin and improve its barrier function over a short period. We studied the effects of glycerol and xylitol on the physiological properties and morphology of the skin after longer-term application. Twelve volunteers with dry skin were examined. Three areas on the arms were determined. Area 1 served as untreated control. The vehicle was applied to area 2, while area 3 was treated twice daily with a formulation containing glycerol (5%) and xylitol (5%) for 14 days. Transepidermal water loss (TEWL), hydration and biomechanical properties of the skin were monitored. Biopsies were taken for routine histology and immunohistochemistry for filaggrin and matrix metalloproteinase-1 (MMP-1). The polyols increased the skin hydration and protein quantity of filaggrin, elevated the interdigitation index, decreased the TEWL and improved the biomechanical properties of the skin, but did not change the protein expression of MMP-1. A combination of glycerol and xylitol can be useful additional therapy for dry skin.

  8. Effects of TPA on short-circuit current across frog skin

    SciTech Connect

    Mauro, T.; O'Brien, T.G.; Civan, M.M.

    1987-02-01

    TPA (12-O-tetradecanoylphorbol-13-acetate) is an effective tumor promoter that affects a variety of ion transport processes. To examine the relationship between effects on transport and growth and differentiation, the authors have been studying the actions of TPA on frog skin, a particularly well-characterized epithelium. They have reported that high concentrations of TPA stimulate base-line short-circuit current (I/sub SC/) and inhibit the subsequent natriferic action of vasopressin. The current study of 89 preparations extends those findings. The K/sub m/ of the stimulatory effect of TPA is approx. 3 nM; this high affinity indicates that the transport phenomenon does not simply reflect a nonspecific interaction of phorbol ester with the plasma membranes. TPA acts largely or entirely at the mucosal surface of both split and whole skins; thus the sidedness of the effect does not arise from adsorption onto the underlying connective tissue when TPA is applied to the serosal surface of whole skin. Amiloride, an inhibitor of apical Na entry, abolishes I/sub SC/ across frog skins pretreated with TPA. The phorbol ester also increases I/sub SC/ across split skins, preparations which do not produce net Cl transport. The present results indicate that frog skin is highly responsive to TPA at concentrations known to activate protein kinase C in broken-cell preparations. The actions on I/sub SC/ appear to reflect changes in transepithelial Na transport modulated at the apical membranes. The full biochemical events triggered by TPA remain to be clarified; in part, TPA's actions may be mediated by leukotrienes produced by activation of the lipoxygenase pathway of arachidonic acid metabolism.

  9. The topical use of non-thermal dielectric barrier discharge (DBD): nitric oxide related effects on human skin.

    PubMed

    Heuer, Kiara; Hoffmanns, Martin A; Demir, Erhan; Baldus, Sabrina; Volkmar, Christine M; Röhle, Mirco; Fuchs, Paul C; Awakowicz, Peter; Suschek, Christoph V; Opländer, Christian

    2015-01-30

    Dielectric barrier discharge (DBD) devices generate air plasma above the skin containing active and reactive species including nitric oxide (NO). Since NO plays an essential role in skin physiology, a topical application of NO by plasma may be useful in the treatment of skin infections, impaired microcirculation and wound healing. Thus, after safety assessments of plasma treatment using human skin specimen and substitutes, NO-penetration through the epidermis, the loading of skin tissue with NO-derivates in vitro and the effects on human skin in vivo were determined. After the plasma treatment (0-60 min) of skin specimen or reconstructed epidermis no damaging effects were found (TUNEL/MTT). By Franz diffusion cell experiments plasma-induced NO penetration through epidermis and dermal enrichment with NO related species (nitrite 6-fold, nitrate 7-fold, nitrosothiols 30-fold) were observed. Furthermore, skin surface was acidified (~pH 2.7) by plasma treatment (90 s). Plasma application on the forearms of volunteers increased microcirculation fourfold in 1-2 mm and twofold in 6-8 mm depth in the treated skin areas. Regarding the NO-loading effects, skin acidification and increase in dermal microcirculation, plasma devices represent promising tools against chronic/infected wounds. However, efficacy of plasma treatment needs to be quantified in further studies and clinical trials.

  10. Titanium Dioxide Nanoparticle Penetration into the Skin and Effects on HaCaT Cells.

    PubMed

    Crosera, Matteo; Prodi, Andrea; Mauro, Marcella; Pelin, Marco; Florio, Chiara; Bellomo, Francesca; Adami, Gianpiero; Apostoli, Pietro; De Palma, Giuseppe; Bovenzi, Massimo; Campanini, Marco; Filon, Francesca Larese

    2015-08-07

    Titanium dioxide nanoparticles (TiO2NPs) suspensions (concentration 1.0 g/L) in synthetic sweat solution were applied on Franz cells for 24 h using intact and needle-abraded human skin. Titanium content into skin and receiving phases was determined. Cytotoxicity (MTT, AlamarBlue(®) and propidium iodide, PI, uptake assays) was evaluated on HaCat keratinocytes after 24 h, 48 h, and seven days of exposure. After 24 h of exposure, no titanium was detectable in receiving solutions for both intact and damaged skin. Titanium was found in the epidermal layer after 24 h of exposure (0.47 ± 0.33 μg/cm(2)) while in the dermal layer, the concentration was below the limit of detection. Damaged skin, in its whole, has shown a similar concentration (0.53 ± 0.26 μg/cm(2)). Cytotoxicity studies on HaCaT cells demonstrated that TiO2NPs induced cytotoxic effects only at very high concentrations, reducing cell viability after seven days of exposure with EC50s of 8.8 × 10(-4) M (MTT assay), 3.8 × 10(-5) M (AlamarBlue(®) assay), and 7.6 × 10(-4) M (PI uptake, index of a necrotic cell death). Our study demonstrated that TiO2NPs cannot permeate intact and damaged skin and can be found only in the stratum corneum and epidermis. Moreover, the low cytotoxic effect observed on human HaCaT keratinocytes suggests that these nano-compounds have a potential toxic effect at the skin level only after long-term exposure.

  11. Meloxicam transdermal delivery: effect of eutectic point on the rate and extent of skin permeation

    PubMed Central

    Mohammadi-Samani, Soliman; Yousefi, Gholamhossein; Mohammadi, Farhad; Ahmadi, Fatemeh

    2014-01-01

    Objective(s): Drug delivery through the skin can transfer therapeutic levels of drugs for pharmacological effects. Analgesics such as NSAIDs have gastrointestinal side effects and topical dosage forms of these drugs are mainly preferred, especially for local pains. Meloxicam is one of NSAIDs with no topical form in the market. In this research, we attempted to quantify the skin permeation of a meloxicam topical preparation and to show how permeation would be increased by using thymol as an enhancer. The effect of eutectic point of drug and thymol mixture on rate and extent of skin permeation was also studied. Materials and Methods: Different mixtures of thymol and meloxicam (2:8, 4:6, 5:5, 6:4, 8:2) were prepared and their melting point were obtained by differential scanning calorimetry. Then drug permeation was measured using diffusion cells and the Guinea pig skin. Results: Mixtures in ratios 5:5 and 4:6 of meloxicam / thymol showed a new endotherm at 149 and 140°C in DSC thermograms. The permeability of meloxicam from the creams containing 6:4, 5:5 and 4:6 ratios of meloxicam to thymol were 4.71, 15.2, 22.06 µg/cm2 respectively. This was significantly different from the cream of pure meloxicam (3.76 µg/cm2). Conclusion: This study set out to determine that thymol plays as a skin permeation enhancer and increases the meloxicam skin absorption and this enhancement is significant at the eutectic point of drug-enhancer mixture. PMID:24711894

  12. Titanium Dioxide Nanoparticle Penetration into the Skin and Effects on HaCaT Cells

    PubMed Central

    Crosera, Matteo; Prodi, Andrea; Mauro, Marcella; Pelin, Marco; Florio, Chiara; Bellomo, Francesca; Adami, Gianpiero; Apostoli, Pietro; De Palma, Giuseppe; Bovenzi, Massimo; Campanini, Marco; Larese Filon, Francesca

    2015-01-01

    Titanium dioxide nanoparticles (TiO2NPs) suspensions (concentration 1.0 g/L) in synthetic sweat solution were applied on Franz cells for 24 h using intact and needle-abraded human skin. Titanium content into skin and receiving phases was determined. Cytotoxicity (MTT, AlamarBlue® and propidium iodide, PI, uptake assays) was evaluated on HaCat keratinocytes after 24 h, 48 h, and seven days of exposure. After 24 h of exposure, no titanium was detectable in receiving solutions for both intact and damaged skin. Titanium was found in the epidermal layer after 24 h of exposure (0.47 ± 0.33 μg/cm2) while in the dermal layer, the concentration was below the limit of detection. Damaged skin, in its whole, has shown a similar concentration (0.53 ± 0.26 μg/cm2). Cytotoxicity studies on HaCaT cells demonstrated that TiO2NPs induced cytotoxic effects only at very high concentrations, reducing cell viability after seven days of exposure with EC50s of 8.8 × 10−4 M (MTT assay), 3.8 × 10−5 M (AlamarBlue® assay), and 7.6 × 10−4 M (PI uptake, index of a necrotic cell death). Our study demonstrated that TiO2NPs cannot permeate intact and damaged skin and can be found only in the stratum corneum and epidermis. Moreover, the low cytotoxic effect observed on human HaCaT keratinocytes suggests that these nano-compounds have a potential toxic effect at the skin level only after long-term exposure. PMID:26262634

  13. Development of effective skin cancer treatment and prevention in xeroderma pigmentosum.

    PubMed

    Lambert, W Clark; Lambert, Muriel W

    2015-01-01

    Xeroderma pigmentosum (XP) is a rare, recessively transmitted genetic disease characterized by increasingly marked dyspigmentation and xerosis (dryness) of sun-exposed tissues, especially skin. Skin cancers characteristically develop in sun-exposed sites at very much earlier ages than in the general population; these are often multiple and hundreds or even thousands may develop. Eight complementation groups have been identified. Seven groups, XP-A…G, are associated with defective genes encoding proteins involved in the nucleotide excision DNA repair (NER) pathway that recognizes and excises mutagenic changes induced in DNA by sunlight; the eighth group, XP-V, is associated with defective translesion synthesis (TLS) bypassing such alterations. The dyspigmentation, xerosis and eventually carcinogenesis in XP patients appear to be due to their cells' failure to respond properly to these mutagenic DNA alterations, leading to mutations in skin cells. A subset of cases, especially those in some complementation groups, may develop neurological degeneration, which may be severe. However, in most XP patients, in the past the multiple skin cancers have led to death at an early age due to either metastases or sepsis. Using either topical 5-fluorouracil or imiquimod, we have developed a protocol that effectively prevents most skin cancer development in XP patients.

  14. The effect of region of application on absorption of ethanol and hexanol through canine skin.

    PubMed

    Mills, P C; Magnusson, B M; Cross, S E

    2004-02-01

    The effect of region of application on the percutaneous penetration of solutes with differing lipophilicity was investigated in canine skin. Skin from the thorax, neck, back, groin, and axilla regions was harvested from Greyhound dogs and placed in Franz-type diffusion cells. Radiolabelled (14C) ethanol (Log P 0.19) or hexanol (Log P 1.94) was applied to each skin section for a total of 5h. The permeability coefficient (kP, cm h(-1)) and residue of alcohol remaining in the skin were significantly (P=0.001) higher for hexanol compared to ethanol. In contrast, ethanol had a far greater maximum flux (Jmax, mol (cm2)(-1) h(-1)) than hexanol (P=0.001). A comparison of regional differences shows the kP and Jmax for ethanol in the groin was significantly lower (P=0.035) than the back. The kP and Jmax for hexanol were significantly higher (P=0.001) in the axilla than the other four skin sites. An understanding of factors influencing percutaneous drug movement is important when formulating topical preparations for the dog.

  15. Antioxidant activities and skin hydration effects of rice bran bioactive compounds entrapped in niosomes.

    PubMed

    Manosroi, Aranya; Chutoprapat, Romchat; Sato, Yuji; Miyamoto, Kukizo; Hsueh, Kesyin; Abe, Masahiko; Manosroi, Worapaka; Manosroi, Jiradej

    2011-03-01

    Bioactive compounds [ferulic acid (F), gamma-oryzanol (O) and phytic acid (P)] in rice bran have been widely used as antioxidants in skin care products. However, one of the major problems of antioxidants is the deterioration of their activities during long exposure to air and light. Niosomes have been used to entrap many degradable active agents not only for stability improvement, but also for increasing skin hydration. The objective of this study was to determine antioxidant activities [by in vitro ORAC (oxygen radical absorbance capacity) and ex vivo lipid peroxidation inhibition assay] and in vivo human skin hydration effects of gel and cream containing the rice bran extracts entrapped in niosomes. Gel and cream containing the rice bran extracts entrapped in niosomes showed higher antioxidant activity (ORAC value) at 20-28 micromol of Trolox equivalents (TE) per gram of the sample than the placebo gel and cream which gave 16-18 micromolTE/g. Human sebum treated with these formulations showed more lipid peroxidation inhibition activity than with no treatment of about 1.5 times. The three different independent techniques including corneometer, vapometer and confocal Raman microspectroscopy (CRM) indicated the same trend in human skin hydration enhancement of the gel or cream formulations containing the rice bran extracts entrapped in niosomes of about 20, 3 and 30%, respectively. This study has demonstrated the antioxidant activities and skin hydration enhancement of the rice bran bioactive compounds when entrapped in niosomes and incorporated in cream formulations.

  16. Effects of housing conditions on the development of wet skin lesions in the NOA mouse.

    PubMed

    Kondo, Taizo; Kondo, Toshio; Shiomoto, Yasuhisa; Momii, Akira

    2005-04-01

    The effects of housing on the onset time and prevalence of wet skin lesions were investigated in NOA mice, which spontaneously develop these lesions at a high rate. Wet skin lesions developed earliest in mice that were housed individually. For mice that were housed in groups, the lesions developed earlier in mice with non-littermate group housing than in mice with littermate group housing. The prevalence of lesions was in the following order: individual housing > non-littermate group housing > littermate group housing. These results suggest that socio-psychological factors are involved in the etiology of wet skin lesions in the NOA mouse. Under individual housing conditions, two other novel characters of the NOA mouse were also observed, specifically, development of dry skin and wet skin lesions at the tail root. These characteristics developed early and with high prevalence and were easily observed on external examination. Therefore, these novel characteristics observed in NOA mice are potential markers of the psychological state of the animals.

  17. The pretreatment effect of chemical skin penetration enhancers in transdermal drug delivery using iontophoresis.

    PubMed

    Choi, E H; Lee, S H; Ahn, S K; Hwang, S M

    1999-01-01

    The transdermal drug delivery (TDD) system has largely been divided into physical, biochemical and chemical methods. Recently, combinations of these methods were introduced for more effective delivery with less side effects. We performed this study to identify the effectiveness and mechanism of TDD using the physical method, 'iontophoresis', plus the chemical method, 'pretreatment with chemical enhancer'. The action sites of chemical enhancers in the stratum corneum (SC) were observed by electron microscope. We also studied whether this combined method synergistically impaired the skin barrier. To confirm the synergistic effect on skin penetration by this combined method, we measured the blood glucose level after insulin iontophoresis following a chemical enhancer pretreatment in rabbits. The results were that (1) dilatation of the intercellular lipid layers of the SC and lacunae was prominent in pretreatment with chemical enhancers inducing high transepidermal water loss (TEWL); (2) the skin barrier impairment, with repeated treatments showing an increased TEWL and also epidermal proliferation, was increased with the chemical enhancers that showed a high TEWL immediately after treatment; (3) the combination of chemical enhancer pretreatment and iontophoresis showed no synergistic impairment of the skin barrier, and (4) the chemical enhancer pretreatment with greater impairment of the skin barrier could increase the delivery of insulin by iontophoresis. The results showed that a combination of chemical enhancer pretreatment and iontophoresis could deliver drugs more effectively than iontophoresis alone. Our proposed theory is that iontophoretic drug delivery may be easier through the dilated intercellular spaces of the SC which have a lower electrical impedance following the chemical enhancer pretreatment. Because the effect and the side effects in the combination are decided by the chemical enhancer rather than iontophoresis, the development of proper chemical

  18. Skin Diseases: Skin Health and Skin Diseases

    MedlinePlus

    Skip Navigation Bar Home Current Issue Past Issues Skin Diseases Skin Health and Skin Diseases Past Issues / Fall 2008 Table of Contents ... acne to wrinkles Did you know that your skin is the largest organ of your body? It ...

  19. The expression of KRT2 and its effect on melanogenesis in alpaca skins.

    PubMed

    Cui, Yucong; Song, Yajun; Geng, Qingling; Ding, Zengfeng; Qin, Yilong; Fan, Ruiwen; Dong, Changsheng; Geng, Jianjun

    2016-06-01

    In order to investigate the effects of the keratin 2 (KRT2) on alpaca melanocyte in vivo and vitro, the immunohistochemistry (IHC), quantitative real-time PCR (qPCR), Western blot, and alpaca melanocytes transfection methods were used. The results showed that mRNA and protein expression of KRT2 was highly expressed in brown skin in comparison with that in white skin. Moreover, we found that KRT2 was expressed in alpaca melanocytes in vitro by immunocytochemistry. After transfection with KRT2 in alpaca melanocytes, the relative mRNA and protein expression of KRT2, microphthalmia-associtated transcription factor (MITF), tyrosinase (TYR) and tyrosinase-related protein 1 (TYRP1) in alpaca skin melanocytes was increased with significant differences; a further result was the increase of melanin production. The results suggested that KRT2 functions in alpaca hair color formation, which offered an essential theoretical basis for further exploration of the role of melanogenesis.

  20. Light and temperature effects on phenolics in dark-skinned grapes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During the past decade we refined our understanding of the effects of solar radiation and temperature on the accumulation of phenolic compounds in grapes in the field, particularly dark-skinned cultivars used for red wine. The work was precipitated by nearly universal prescriptive advice a decade pr...

  1. Effects of palmitoyl-KVK-L-ascorbic acid on skin wrinkles and pigmentation.

    PubMed

    Kim, Hyeong Mi; An, Hyo Sun; Bae, Jung-Soo; Kim, Jung Yun; Choi, Chi Ho; Kim, Ju Yeon; Lim, Joo Hyuck; Choi, Joon-Hun; Song, Hyunnam; Moon, Sung Ho; Park, Young Jun; Chang, Shin-Jae; Choi, Sun Young

    2017-03-16

    Wrinkle formation and abnormal pigmentation are major clinical alterations associated with skin aging. As the aim of our study was to investigate the effects of palmitoyl-KVK-L-ascorbic acid on skin aging, the anti-wrinkle and depigmentation effects of palmitoyl-KVK-L-ascorbic acid were evaluated by measuring collagen expression in dermal fibroblast cells and inhibition of melanogenesis in B16F1 cells, respectively. The anti-aging effect of palmitoyl-KVK-L-ascorbic acid cream was also evaluated against a placebo cream in a clinical trial. Our results confirmed that the expression of type Ι collagen in dermal fibroblast cells treated with palmitoyl-KVK-L-ascorbic acid (0.1-4 μg/mL) increased in a dose-dependent manner. In B16F1 cells, treatment with 20 μg/mL palmitoyl-KVK-L-ascorbic acid reduced the melanin content by approximately 20% compared to alpha-melanocyte stimulating hormone treatment. In the clinical trial, application of palmitoyl-KVK-L-ascorbic acid cream led to an improvement in skin roughness and lightness in 12 and 8 weeks, respectively. Our data show that palmitoyl-KVK-L-ascorbic acid is an effective anti-aging agent that reduces wrinkles and abnormal skin pigmentation.

  2. High School Students' Perceptions of How Major Global Environmental Effects Might Cause Skin Cancer.

    ERIC Educational Resources Information Center

    Boyes, Edward; Stanisstreet, Martin

    1998-01-01

    Quantifies beliefs of high school students about links between skin cancer and global environmental effects. Some students confused the action of heat rays with that of ultraviolet rays and also thought that raised temperatures are culpable. Only one in 10 held the scientifically correct model: that ozone depletion via higher penetration of…

  3. Chemical and engineering approaches to enable organic field-effect transistors for electronic skin applications.

    PubMed

    Sokolov, Anatoliy N; Tee, Benjamin C-K; Bettinger, Christopher J; Tok, Jeffrey B-H; Bao, Zhenan

    2012-03-20

    Skin is the body's largest organ and is responsible for the transduction of a vast amount of information. This conformable material simultaneously collects signals from external stimuli that translate into information such as pressure, pain, and temperature. The development of an electronic material, inspired by the complexity of this organ is a tremendous, unrealized engineering challenge. However, the advent of carbon-based electronics may offer a potential solution to this long-standing problem. In this Account, we describe the use of an organic field-effect transistor (OFET) architecture to transduce mechanical and chemical stimuli into electrical signals. In developing this mimic of human skin, we thought of the sensory elements of the OFET as analogous to the various layers and constituents of skin. In this fashion, each layer of the OFET can be optimized to carry out a specific recognition function. The separation of multimodal sensing among the components of the OFET may be considered a "divide and conquer" approach, where the electronic skin (e-skin) can take advantage of the optimized chemistry and materials properties of each layer. This design of a novel microstructured gate dielectric has led to unprecedented sensitivity for tactile pressure events. Typically, pressure-sensitive components within electronic configurations have suffered from a lack of sensitivity or long mechanical relaxation times often associated with elastomeric materials. Within our method, these components are directly compatible with OFETs and have achieved the highest reported sensitivity to date. Moreover, the tactile sensors operate on a time scale comparable with human skin, making them ideal candidates for integration as synthetic skin devices. The methodology is compatible with large-scale fabrication and employs simple, commercially available elastomers. The design of materials within the semiconductor layer has led to the incorporation of selectivity and sensitivity within

  4. Effects of Creating Awareness Through Photographs and Posters on Skin Self-Examination in Nursing Students.

    PubMed

    Erkin, Özüm; Ardahan, Melek; Temel, Ayla Bayık

    2016-04-26

    Nurses can have an influence on primary and secondary prevention of skin cancer. Therefore, it is important to help them acquire knowledge and skills necessary to modify behavior in relation to skin cancers. The aim of this study was to examine effects of creating awareness through photographs and posters on knowledge and skills of skin self-examination in nursing students. The study had a quasi-experimental design with a pretest and a posttest in a single group. The study population included 249 last-year nursing students in Turkey. Non-probability sampling was used to reach the population. The study sample was composed of 201 students volunteering to participate in the study, and the response rate was 81 %. Of the students, 85.1 % (n = 171) were female and the mean age of the students was 22.18 ± 0.78 years. Of the students, 94.5 % did not know the asymmetry, border, color, diameter, evolution (ABCDE) criteria on the pretest, but this rate decreased to 20.9 % on the posttest. The mean score for knowledge of symptoms of skin cancer was 10.95 ± 1.37 on the pretest and 11.48 ± 0.90 on the posttest. There was a significant linear increase in the scores for knowledge of the symptoms (F = 7.874, p < 0.001) after the intervention with photographs and posters. The students were observed to learn the ABCDE criteria and had increased knowledge of skin cancer symptoms after the intervention using photographs and posters. Photographs and posters are effective tools which can be used to increase awareness of skin self-examination.

  5. Effects of Porcine Placenta Extract Ingestion on Ultraviolet B-induced Skin Damage in Hairless Mice

    PubMed Central

    Hong, Ki-Bae; Park, Yooheon; Kim, Jae Hwan; Kim, Jin Man; Suh, Hyung Joo

    2015-01-01

    The aim of our study was to evaluate the potential benefits of an oral supplement containing porcine placenta extract (PPE) on skin parameters related to cutaneous physiology and aging. PPEs were administered orally to hairless mice for 12 wk. The effects of oral PPE administration on skin water-holding capacity and Transepidermal Water Loss (TEWL) were similar to those of oral collagen (HYCPU2) administered as a positive control. Magnified photographs and replica images showed a reduction in UVB-induced wrinkle formation after collagen and PPE treatments. PPE treatments ameliorated the thicker skin surface that results from UVB exposure, based on a histological examination of skin tissue. The groups that were orally administered PPE (0.05%, OL; 0.1%, OH group) showed significantly reduced Matrix Metaloproteinase-2 (MMP-2) mRNA expression levels compared with the UVB control (Con), by 33.5% and 35.2%, respectively. The mRNA expression of another collagen-degrading protein, MMP-9, was also significantly lower in the groups that received oral administration of PPE (especially in the OH group) than in the control group. Additionally, oral administration of PPE significantly upregulated tissue inhibitor of metalloproteinase-1 (TIMP-1) and -2 mRNA expression levels compared with expression levels in the control group (p<0.05). This indicates that orally administered PPE activated the expression of Timp-1 and -2, inhibitors of MMP, which is responsible for collagen degradation in skin. Taken together, we propose that long-term oral administration of PPE might have a beneficial effect with respect to skin photo-aging. PMID:26761856

  6. Therapeutic effect of ethyl acetate extract from Asparagus cochinchinensis on phthalic anhydride-induced skin inflammation

    PubMed Central

    Sung, Ji-Eun; Lee, Hyun-Ah; Kim, Ji-Eun; Go, Jun; Seo, Eun-Ji; Yun, Woo-Bin; Kim, Dong-Seob; Son, Hong-Joo; Lee, Chung-Yeoul; Lee, Hee-Seob

    2016-01-01

    Asparagus cochinchinensis has been used to treat various diseases including fever, cough, kidney disease, breast cancer, inflammatory disease and brain disease, while IL-4 cytokine has been considered as key regulator on the skin homeostasis and the predisposition toward allergic skin inflammation. However, few studies have investigated its effects and IL-4 correlation on skin inflammation to date. To quantitatively evaluate the suppressive effects of ethyl acetate extracts of A. cochinchinensis (EaEAC) on phthalic anhydride (PA)-induced skin inflammation and investigate the role of IL-4 during their action mechanism, alterations in general phenotype biomarkers and luciferase-derived signals were measured in IL-4/Luc/CNS-1 transgenic (Tg) mice with PA-induced skin inflammation after treatment with EaEAC for 2 weeks. Key phenotype markers including lymph node weight, immunoglobulin E (IgE) concentration, epidermis thickness and number of infiltrated mast cells were significantly decreased in the PA+EaEAC treated group compared with the PA+Vehicle treated group. In addition, expression of IL-1β and TNF-α was also decreased in the PA+EaEAC cotreated group, compared to PA+Vehicle treated group. Furthermore, a significant decrease in the luciferase signal derived from IL-4 promoter was detected in the abdominal region, submandibular lymph node and mesenteric lymph node of the PA+EaEAC treated group, compared to PA+Vehicle treated group. Taken together, these results suggest that EaEAC treatment could successfully improve PA-induced skin inflammation of IL-4/Luc/CNS-1 Tg mice, and that IL-4 cytokine plays a key role in the therapeutic process of EaEAC. PMID:27051441

  7. Effects of prolactin administered to a perfused area of the skin of Angora goats.

    PubMed

    Puchala, R; Pierzynowski, S G; Wuliji, T; Goetsch, A L; Soto-Navarro, S A; Sahlu, T

    2003-01-01

    It is suspected that prolactin may affect mohair growth; therefore, effects of infusing prolactin on mohair growth were investigated using a skin perfusion technique. Seven Angora wethers (average body weight, 30 +/- 3 kg) were implanted bilaterally with silicon catheters into the superficial branches of the deep circumflex iliac artery and vein. For the first 14 d of the experiment, animals were infused (2.4 mL/h) with prolactin (one side) or control (other side) into the deep circumflex iliac arteries. The infusion rate of prolactin was 2.21 mg/d and was calculated to triple prolactin blood concentration in the perfused region. The area of skin supplied by the deep circumflex iliac artery was approximately 240 cm2. Two weeks after the cessation of infusions, 100-cm2 areas within the perfused regions were shorn to determine mohair growth. Greasy and clean mohair production was decreased (P < 0.05) by prolactin compared with control (3.79 vs 4.62 and 3.02 vs 3.67 g/[100 cm2 x 28 d], respectively). Oxygen satura tion in blood hemoglobin from the deep circumflex iliac veins was greater (P < 0.02) on the side infused with prolactin than on the control side (75.1 vs 68.2%). Higher concentrations of methionine, lysine, valine, isoleucine, and leucine were observed in blood of the deep circumflex iliac vein on the side infused with prolactin vs that infused with control (P < 0.05). In conclusion, direct skin infusion with prolactin decreased mohair fiber synthesis by the skin and may have concomitantly lessened oxygen consumption. Thus, effects of increasing prolactin concentration approximately two-fold in the skin on mohair fiber growth may not be limited to simple competition for nutrients between skin and other tissues such as the mammary gland.

  8. Skin penetration and antioxidant effect of cosmeto-textiles with gallic acid.

    PubMed

    Alonso, C; Martí, M; Barba, C; Lis, M; Rubio, L; Coderch, L

    2016-03-01

    In this work, the antioxidant gallic acid (GA) has been encapsulated in microspheres prepared with poly-ε-caprolactone (PCL) and incorporated into polyamide (PA) obtaining the cosmeto-textile. The topical application of the cosmeto-textile provides a reservoir effect in the skin delivery of GA. The close contact of the cosmeto-textile, containing microsphere-encapsulated GA (ME-GA), with the skin and their corresponding occlusion, may be the main reasons that explain the crossing of active principle (GA) through the skin barrier, located in the stratum corneum, and its penetration into the different compartments of the skin, epidermis and dermis. An ex vivo assessment was performed to evaluate the antioxidant effect of the ME-GA on the stratum corneum (SC) using the thiobarbituric acid-reactive species (TBARS) test. The test is based on a non-invasive ex vivo methodology that evaluates lipid peroxides formed in the outermost layers of the SC from human volunteers after UV radiation to determine the effectiveness of an antioxidant. In this case, a ME-GA cosmeto-textile or ME-GA formulation were applied to the skin in vivo and lipid peroxidation (LPO) in the horny layer were determined after UV irradiation. This methodology may be used as a quality control tool to determine ex vivo the percentage of LPO inhibition on human SC for a variety of antioxidants that are topically applied, in this case GA. Results show that LPO formation was inhibited in human SC when GA was applied directly or embedded in the cosmeto-textile, demonstrating the effectiveness of both applications. The percentage of LPO inhibition obtained after both topical applications was approximately 10% for the cosmeto-textile and 41% for the direct application of microspheres containing GA. This methodology could be used to determine the effectiveness of topically applied antioxidants encapsulated in cosmeto-textiles on human SC.

  9. Aqueous Extract of Clerodendranthus spicatus Exerts Protective Effect on UV-Induced Photoaged Mice Skin

    PubMed Central

    Li, Cai-lan

    2016-01-01

    Clerodendranthus spicatus (Thunb.) C.Y.Wu (CS) is commonly used to treat kidney diseases in traditional Chinese medicine for its prominent anti-inflammatory effect and nourishing function to kidneys. In this study, aqueous extract of CS was assessed for its protective effect on UV-induced skin damage of mice. The chemical compositions of CS aqueous extract were determined by HPLC-ESI-MS/MS, in which 10 components were identified. During the experimental period, CS (0.9, 1.8, and 3.6 g/mL) was externally applied to shaved dorsal skins of mice prior to UV irradiation, daily for ten weeks. The results presented that CS (3.6 g/mL) apparently improved photodamaged skin appearance such as erythema, edema, and coarseness. The abnormal epidermal thickening was significantly reduced, and the dermal structures became more complete. The underlying protective mechanisms were associated with improving antioxidant enzymes activities including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), downregulating inflammatory cytokines (IL-1β, IL-6, TNF-α, COX-2, and PGE2) expressions, recovering collagen density, and reducing matrix metalloproteinases productions. Sun protection factor of CS (3.6 g/mL) was 16.21 ± 0.03. Our findings for the first time demonstrated that CS had therapeutic effect on the photoaged skin. The results indicated that CS is a potential agent for photoprotective cosmetics. PMID:27847530

  10. Effect of piracetam and nimodipine on full-thickness skin burns in rabbits.

    PubMed

    Sari, Elif; Dincel, Gungor C

    2016-08-01

    The potential of several drugs for full-thickness skin burns has been investigated, but the treatment of such burns remains a challenge in plastic surgery. The present study was designed to determine the effect of systemic and topical administration of piracetam and nimodipine on full-thickness skin burn wound healing. A total of 36 New Zealand male rabbits were divided into six groups. Full-thickness skin burns were produced in all the groups, except the control group. Piracetam was administered systemically (piracetam-IV) and topically (piracetam-C) for 14 days, and nimodipine was administered systemically (nimodipine-IV) and topically (nimodipine-C) over the burn wounds for 14 days. The sham group underwent burn injury but was not administered any drug. After 21 days, gross examination and histopathological analysis were performed and the results were compared statistically. Nimodipine-C and nimodipine-IV had no effect on burn wound healing. However, both piracetam-IV and piracetam-C significantly enhanced the healing of the full-thickness skin burn wounds, although the latter was more effective, useful and practical in burn wound healing. The histopathological features of the wounds in the piracetam-C group were closer to those of the control group than those of the other groups. Piracetam-C rather than piracetam-IV may promote full-thickness burn wound healing in rabbits.

  11. Differential cytotoxic effects of graphene and graphene oxide on skin keratinocytes

    PubMed Central

    Pelin, Marco; Fusco, Laura; León, Verónica; Martín, Cristina; Criado, Alejandro; Sosa, Silvio; Vázquez, Ester; Tubaro, Aurelia; Prato, Maurizio

    2017-01-01

    Impressive properties make graphene-based materials (GBMs) promising tools for nanoelectronics and biomedicine. However, safety concerns need to be cleared before mass production of GBMs starts. As skin, together with lungs, displays the highest exposure to GBMs, it is of fundamental importance to understand what happens when GBMs get in contact with skin cells. The present study was carried out on HaCaT keratinocytes, an in vitro model of skin toxicity, on which the effects of four GBMs were evaluated: a few layer graphene, prepared by ball-milling treatment (FLG), and three samples of graphene oxide (GOs, a research-grade GO1, and two commercial GOs, GO2 and GO3). Even though no significant effects were observed after 24 h, after 72 h the less oxidized compound (FLG) was the less cytotoxic, inducing mitochondrial and plasma-membrane damages with EC50s of 62.8 μg/mL (WST-8 assay) and 45.5 μg/mL (propidium iodide uptake), respectively. By contrast, the largest and most oxidized compound, GO3, was the most cytotoxic, inducing mitochondrial and plasma-membrane damages with EC50s of 5.4 and 2.9 μg/mL, respectively. These results suggest that only high concentrations and long exposure times to FLG and GOs could impair mitochondrial activity associated with plasma membrane damage, suggesting low cytotoxic effects at the skin level. PMID:28079192

  12. Differential cytotoxic effects of graphene and graphene oxide on skin keratinocytes

    NASA Astrophysics Data System (ADS)

    Pelin, Marco; Fusco, Laura; León, Verónica; Martín, Cristina; Criado, Alejandro; Sosa, Silvio; Vázquez, Ester; Tubaro, Aurelia; Prato, Maurizio

    2017-01-01

    Impressive properties make graphene-based materials (GBMs) promising tools for nanoelectronics and biomedicine. However, safety concerns need to be cleared before mass production of GBMs starts. As skin, together with lungs, displays the highest exposure to GBMs, it is of fundamental importance to understand what happens when GBMs get in contact with skin cells. The present study was carried out on HaCaT keratinocytes, an in vitro model of skin toxicity, on which the effects of four GBMs were evaluated: a few layer graphene, prepared by ball-milling treatment (FLG), and three samples of graphene oxide (GOs, a research-grade GO1, and two commercial GOs, GO2 and GO3). Even though no significant effects were observed after 24 h, after 72 h the less oxidized compound (FLG) was the less cytotoxic, inducing mitochondrial and plasma-membrane damages with EC50s of 62.8 μg/mL (WST-8 assay) and 45.5 μg/mL (propidium iodide uptake), respectively. By contrast, the largest and most oxidized compound, GO3, was the most cytotoxic, inducing mitochondrial and plasma-membrane damages with EC50s of 5.4 and 2.9 μg/mL, respectively. These results suggest that only high concentrations and long exposure times to FLG and GOs could impair mitochondrial activity associated with plasma membrane damage, suggesting low cytotoxic effects at the skin level.

  13. Effects of Vehicles and Enhancers on the Skin Permeation of Phytoestrogenic Diarylheptanoids from Curcuma comosa.

    PubMed

    Tuntiyasawasdikul, Sarunya; Limpongsa, Ekapol; Jaipakdee, Napaphak; Sripanidkulchai, Bungorn

    2017-04-01

    Curcuma comosa (C. comosa) is widely used in traditional medicine as a dietary supplement for health promotion in postmenopausal women in Thailand. It contains several diarylheptanoids, which are considered to be a novel class of phytoestrogens. However, the diarylheptanoids isolated from the plant rhizome are shown to have low oral bioavailability and faster elimination characteristics. The aim of this study was to investigate the permeation behavior of the active compounds of diarylheptanoids. The effects of binary vehicle systems and permeation enhancers on diarylheptanoids permeation and accumulation within the skin were studied using side-by-side diffusion cells through the porcine ear skin. Among the tested binary vehicle systems, the ethanol/water vehicle appeared to be the most effective system for diarylheptanoids permeation with the highest flux and shortest lag time. The presence of transcutol in the vehicle system significantly increased diarylheptanoid's permeation and accumulation within the skin in a concentration-dependent manner. Although the presence of terpenes in formulation decreased the flux of diarylheptanoids, it raised the amount of diarylheptanoids retained within the skin substantially. Based on the feasibility of diarylheptanoid permeation, C. comosa extract should be further developed into an effective transdermal product for health benefits and hormone replacement therapy.

  14. Effect of cyclic aromatics on sodium active transport in frog skin

    SciTech Connect

    Blankemeyer, J.T.; Bowerman, M.C. )

    1993-01-01

    A modified glass Ussing-chamber was used to mount the skin. The electrical potential difference (PD) was measured by two 3% agar-frog Ringer's bridges. Current (i.e. short-circuit current, or ISC) was passed by Ag-AgCl electrodes placed so that current density was uniform across the skin. Ringer's solution, bathing each side of the frog skin, was stirred and aerated by gas-lift pumps. The effect of toxicants on the ISC was determined by using the 15 min prior to toxicant administration as a control period, then calculating the change in ISC during the toxicant period as a percent of the control ISC. Phenol and benzene are components of crude oil and crude oil waste. These hydrocarbons and phenanthrene were tested for their effect on frog skin. The results show that the effect of organics on sodium active transport of an epithelium is to alter the active transport of sodium ions. 5 refs., 3 figs., 1 tab.

  15. Wall mass transfer and pressure gradient effects on turbulent skin friction

    NASA Technical Reports Server (NTRS)

    Watson, R. D.; Balasubramanian, R.

    1984-01-01

    The effects of mass injection and pressure gradients on the drag of surfaces were studied theoretically with the aid of boundary-layer and Navier-Stokes codes. The present investigation is concerned with the effects of spatially varying the injection in the case of flat-plate drag. Effects of suction and injection on wavy wall surfaces are also explored. Calculations were performed for 1.2 m long surfaces, one flat and the other sinusoidal with a wavelength of 30.5 cm. Attention is given to the study of the effect of various spatial blowing variations on flat-plate skin friction reduction, local skin friction coefficient calculated by finite difference boundary-layer code and Navier-Stokes code, and the effect of phase-shifting sinusoidal mass transfer on the drag of a sinusoidal surface.

  16. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Anomalous Kondo-Switching Effect of a Spin-Flip Quantum Dot Embedded in an Aharonov-Bohm Ring

    NASA Astrophysics Data System (ADS)

    Chen, Xiong-Wen; Shi, Zhen-Gang; Song, Ke-Hui

    2009-11-01

    We theoretically investigate the Kondo effect of a quantum dot embedded in a mesoscopic Aharonov-Bohm (AB) ring in the presence of the spin flip processes by means of the one-impurity Anderson Hamiltonian. Based on the slave-boson mean-field theory, we find that in this system the persistent current (PC) sensitively depends on the parity and size of the AB ring and can be tuned by the spin-flip scattering (R). In the small AB ring, the PC is suppressed due to the enhancing R weakening the Kondo resonance. On the contrary, in the large AB ring, with R increasing, the peak of PC firstly moves up to max-peak and then down. Especially, the PC phase shift of π appears suddenly with the proper value of R, implying the existence of the anomalous Kondo effect in this system. Thus this system may be a candidate for quantum switch.

  17. Measuring the effects of topically applied skin optical clearing agents and modeling the effects and consequences for laser therapies

    NASA Astrophysics Data System (ADS)

    Verkruysse, Wim; Khan, Misbah; Choi, Bernard; Svaasand, Lars O.; Nelson, J. Stuart

    2005-04-01

    Human skin prepared with an optical clearing agent manifests reduced scattering as a result of de-hydration and refractive index matching. This has potentially large effects for laser therapies of several skin lesions such as port wine stain, hair removal and tattoo removal. With most topically applied clearing agents the clearing effect is limited because they penetrate poorly through the intact superficial skin layer (stratum corneum). Agent application modi other than topical are impractical and have limited the success of optical clearing in laser dermatology. In recent reports, however, a mixture of lipofylic and hydrofylic agents was shown to successfully penetrate through the intact stratum corneum layer which has raised new interest in this field. Immediately after application, the optical clearing effect is superficial and, as the agent diffuses through the skin, reduced scattering is manifested in deeper skin layers. For practical purposes as well as to maximize therapeutic success, it is important to quantify the reduced scattering as well as the trans-cutaneous transport dynamics of the agent. We determined the time and tissue depth resolved effects of optically cleared skin by inserting a microscopic reflector array in the skin. Depth dependent light intensity was measured by quantifying the signal of the reflector array with optical coherence tomography. A 1-dimensional mass diffusion model was used to estimate a trans-cutaneous transport diffusion constant for the clearing agent mixture. The results are used in Monte Carlo modeling to determine the optimal time of laser treatment after topical application of the optical clearing agent.

  18. Hydrodynamic function of biomimetic shark skin: effect of denticle pattern and spacing.

    PubMed

    Wen, Li; Weaver, James C; Thornycroft, Patrick J M; Lauder, George V

    2015-11-18

    The structure of shark skin has been the subject of numerous studies and recently biomimetic shark skin has been fabricated with rigid denticles (scales) on a flexible substrate. This artificial skin can bend and generate thrust when attached to a mechanical controller. The ability to control the manufacture of biomimetic shark skin facilitates manipulation of surface parameters and understanding the effects of changing denticle patterns on locomotion. In this paper we investigate the effect of changing the spacing and arrangement of denticles on the surface of biomimetic shark skin on both static and dynamic locomotor performance. We designed 3D-printed flexible membranes with different denticle patterns and spacings: (1) staggered-overlapped, (2) linear-overlapped, and (3) linear-non-overlapped, and compared these to a 3D-printed smooth-surfaced control. These 3D printed shark skin models were then tested in a flow tank with a mechanical flapping device that allowed us to either hold the models in a stationary position or move them dynamically. We swam the membranes at a frequency of 1 Hz with different heave amplitudes (from ±1 cm to ±3 cm) while measuring forces, torques, self-propelled swimming speed, and cost of transport (COT). Static tests revealed drag reduction of denticle patterns compared to a smooth control at low speeds, but increased drag at speeds above 25 cm s(-1). However, during dynamic (swimming) tests, the staggered-overlapped pattern produced the fastest swimming speeds with no significant increase in the COT at lower heave values. For instance, at a heave frequency of 1 Hz and amplitude of ±1 cm, swimming speed of the staggered-overlapped pattern increased by 25.2% over the smooth control. At higher heave amplitudes, significantly faster self-propelled swimming speeds were achieved by the staggered-overlapped pattern, but with higher COT. Only the staggered-overlapped pattern provides a significant swimming performance advantage over the

  19. Comparison of disposable diapers with fluff absorbent and fluff plus absorbent polymers: effects on skin hydration, skin pH, and diaper dermatitis.

    PubMed

    Davis, J A; Leyden, J J; Grove, G L; Raynor, W J

    1989-06-01

    Diaper dermatitis results from the action of a number of physical and chemical factors on the skin. While its etiology is complex, there is agreement that prolonged contact between wet diapers and the skin leading to excessive hydration of the stratum corneum and reduced barrier function is a primary factor. Recent research also indicates that pH elevation resulting from ammonia production increases the probability of skin damage due to fecal enzyme activity. New diapers containing absorbent polymers blended with cellulose fluff in the absorbent core have been developed. The absorbent polymer binds fluids and controls pH in the diaper environment. To assess the effectiveness of these diapers, a clinical study was conducted with approximately 150 infants over 15 weeks, using fluff diapers and absorbent polymer diapers. The results clearly showed that the diapers with absorbent polymer provide a better skin environment than those with fluff only with respect to lower skin wetness and pH control (instrumental measurements). In addition, the clinicians' grades indicated a directional reduction in diaper rash severity.

  20. The effect of skin temperature on performance during a 7.5-km cycling time trial.

    PubMed

    Levels, Koen; de Koning, Jos J; Foster, Carl; Daanen, Hein A M

    2012-09-01

    Aerobic exercise performance is seriously compromised in the heat. Possibly, a high skin temperature causes a rating of perceived exertion (RPE)-mediated decrease in exercise intensity. The purpose of this study was to determine the effect of skin temperature on power output during a 7.5-km cycling time trial. Thirteen well-trained male subjects performed a 7.5-km cycling time trial at 15°C and 50% relative humidity (CONTROL), with radiative heat stress during the time trial, and with (PRECOOL) or without (HEAT) precooling. Heat stress was applied by infrared heaters positioned in front of the cycle ergometer between 1.5 and 6.0 km. Skin, rectal, and pill temperature, power output, heart rate, and RPE were measured during the trial. Despite the lower mean skin temperature at the start of the time trial for PRECOOL compared to HEAT (-2.1 ± 0.7°C; P < 0.01) and CONTROL (-1.8 ± 0.6°C; P < 0.05), and a greater increase in mean skin temperature during the heat stress period for PRECOOL (4.5 ± 1.0°C) and HEAT (3.9 ± 0.8°C) than for CONTROL (-0.3 ± 0.6°C; P < 0.01), no differences in power output were found between HEAT (273 ± 45 W) and CONTROL (284 ± 43 W; P = 0.11) and between HEAT and PRECOOL (266 ± 50 W; P = 0.47). Power output during the time trial was greater for CONTROL than for PRECOOL (P < 0.05). Additionally, no differences were observed in core temperature measures, HR, and RPE. Skin temperature does not affect the selection and modulation of exercise intensity in a 7.5-km cycling time trial.

  1. Effects on detection of radical formation in skin due to solar irradiation measured by EPR spectroscopy.

    PubMed

    Albrecht, Stephanie; Ahlberg, Sebastian; Beckers, Ingeborg; Kockott, Dieter; Lademann, Jürgen; Paul, Victoria; Zastrow, Leonhard; Meinke, Martina C

    2016-10-15

    In various research projects, oxidative stress in irradiated skin was investigated by measuring the production of free radical using EPR spectroscopy. However, comparison of the obtained measuring results proved to be difficult as different preparation parameters were used for those measurements. In the present study the influence of the preparation parameters on the detected radical production was methodically investigated. For this purpose, porcine skin was exposed in situ to UV and VIS-NIR radiation, respectively, while being measured in an X band EPR spectrometer. Prior to the measurements, the skin had been treated with the spin trap N-tert-Butyl-α-phenylnitrone (PBN) and the spin marker 3-(Carboxyl)-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (PCA). The two methods were investigated for quantitative comparability, for advantages and disadvantages and for errors potentially affecting the evaluation of the results. A significant influence of the preparation parameters (concentration and amount of substance) on the detected radical formations could be found. This influence had a nonlinear effect on the detected radical production. 120μl of incubated amount for 1M PBN and for PCA at a concentration of 0.6 and 1.5mM were determined to be the optimum parameters. The incubated skin samples were 1cm in diameter and 300μm thick. Between 22 and 37°C the incubation temperature showed no significant influence on the detected radical production. For the first time it could be demonstrated for PCA-incubated skin that the radiation-induced radical production depends exclusively on the irradiation dose, provided the preparation parameters and the spectral region are kept constant. In addition, the radical production in the UVB-UVA and VIS-NIR spectral regions was measured in PCA- and PBN-treated excised porcine skin. It was found that PBN and PCA provide comparable results for the relative quantity and kinetics of radical production.

  2. Characterization of atopic skin and the effect of a hyperforin-rich cream by laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Meinke, Martina C.; Richter, Heike; Kleemann, Anke; Lademann, Juergen; Tscherch, Kathrin; Rohn, Sascha; Schempp, Christoph M.

    2015-05-01

    Atopic dermatitis (AD) is a multifactorial inflammatory skin disease that affects both children and adults in an increasing manner. The treatment of AD often reduces subjective skin parameters, such as itching, dryness, and tension, but the inflammation cannot be cured. Laser scanning microscopy was used to investigate the skin surface, epidermal, and dermal characteristics of dry and atopic skin before and after treatment with an ointment rich in hyperforin, which is known for its anti-inflammatory effects. The results were compared to subjective parameters and transepidermal water loss, stratum corneum moisture, and stratum corneum lipids. Using biophysical methods, in particular laser scanning microscopy, it was found that atopic skin has distinct features compared to healthy skin. Treatment with a hyperforin-rich ointment resulted in an improvement of the stratum corneum moisture, skin surface dryness, skin lipids, and the subjective skin parameters, indicating that the barrier is stabilized and improved by the ointment. But in contrast to the improved skin surface, the inflammation in the deeper epidermis/dermis often continues to exist. This could be clearly shown by the reflectance confocal microscopy (RCM) measurements. Therefore, RCM measurements could be used to investigate the progress in treatment of atopic dermatitis.

  3. Characterization of atopic skin and the effect of a hyperforin-rich cream by laser scanning microscopy.

    PubMed

    Meinke, Martina C; Richter, Heike; Kleemann, Anke; Lademann, Juergen; Tscherch, Kathrin; Rohn, Sascha; Schempp, Christoph M

    2015-05-01

    Atopic dermatitis (AD) is a multifactorial inflammatory skin disease that affects both children and adults in an increasing manner. The treatment of AD often reduces subjective skin parameters, such as itching, dryness, and tension, but the inflammation cannot be cured. Laser scanning microscopy was used to investigate the skin surface, epidermal, and dermal characteristics of dry and atopic skin before and after treatment with an ointment rich in hyperforin, which is known for its anti-inflammatory effects. The results were compared to subjective parameters and transepidermal water loss, stratum corneum moisture, and stratum corneum lipids. Using biophysical methods, in particular laser scanning microscopy, it was found that atopic skin has distinct features compared to healthy skin. Treatment with a hyperforin-rich ointment resulted in an improvement of the stratum corneum moisture, skin surface dryness, skin lipids, and the subjective skin parameters, indicating that the barrier is stabilized and improved by the ointment. But in contrast to the improved skin surface, the inflammation in the deeper epidermis/dermis often continues to exist. This could be clearly shown by the reflectance confocal microscopy (RCM) measurements. Therefore, RCM measurements could be used to investigate the progress in treatment of atopic dermatitis.

  4. Exposure to Non-Extreme Solar UV Daylight: Spectral Characterization, Effects on Skin and Photoprotection

    PubMed Central

    Marionnet, Claire; Tricaud, Caroline; Bernerd, Françoise

    2014-01-01

    The link between chronic sun exposure of human skin and harmful clinical consequences such as photo-aging and skin cancers is now indisputable. These effects are mostly due to ultraviolet (UV) rays (UVA, 320–400 nm and UVB, 280–320 nm). The UVA/UVB ratio can vary with latitude, season, hour, meteorology and ozone layer, leading to different exposure conditions. Zenithal sun exposure (for example on a beach around noon under a clear sky) can rapidly induce visible and well-characterized clinical consequences such as sunburn, predominantly induced by UVB. However, a limited part of the global population is exposed daily to such intense irradiance and until recently little attention has been paid to solar exposure that does not induce any short term clinical impact. This paper will review different studies on non-extreme daily UV exposures with: (1) the characterization and the definition of the standard UV daylight and its simulation in the laboratory; (2) description of the biological and clinical effects of such UV exposure in an in vitro reconstructed human skin model and in human skin in vivo, emphasizing the contribution of UVA rays and (3) analysis of photoprotection approaches dedicated to prevent the harmful impact of such UV exposure. PMID:25546388

  5. Lippia graveolens photochemopreventive effect against UVB radiation-induced skin carcinogenesis.

    PubMed

    García-Bores, A M; Espinosa-González, A M; Reyna-Campos, A; Cruz-Toscano, S; Benítez-Flores, J C; Hernández-Delgado, C T; Flores-Maya, S; Urzúa-Meza, M; Peñalosa-Castro, I; Céspedes-Acuña, C L; Avila-Acevedo, J G

    2017-02-01

    Lippia graveolens HBK (Mexican oregano) is a species that is regularly used as a condiment in Mexican cuisine. In traditional medicine, it is used for the treatment of respiratory and digestive illnesses, headaches, rheumatism and inflammation-related disorders. The main chemical components reported in this species include the following: terpenoids, iridoids and flavonoids. The aim of this study was to determine the potential photochemopreventive effect of the methanolic extract of Lippia graveolens (MELG) against ultraviolet B (UVB)-induced skin cancer in SKH-1 mice. The phenolic content, radical scavenger activity, penetration and genotoxicity of the MELG were also evaluated. The MELG exhibited scavenging activity against 1,1-diphenyl-2-picrylhydrazyl, superoxide and hydroxyl radicals, and it did not exhibit genotoxic activity in the micronucleus test. In addition, the MELG absorbed UVB (280nm) electromagnetic radiation. The main components detected in the plant extract were naringenin and galangin, and pinocembrin was also isolated and identified through spectroscopic analysis. The MELG demonstrated a photoprotective effect against UVB-induced cell death in Escherichia coli. In chronic challenge experiments, the MELG protected against UVB-induced skin cancer in SKH-1 mice. The MELG penetrated the skin of mice. Topical administration of the MELG protected against chronic UVB-induced damage in mouse SKH-1 skin. Our results suggest that the MELG has photochemopreventive activity and may potentially prevent photo-tumorigenesis.

  6. A useful way to develop effective in vivo skin optical clearing agents.

    PubMed

    Shi, Rui; Guo, Li; Zhang, Chao; Feng, Wei; Li, Peng; Ding, Zhihua; Zhu, Dan

    2016-12-23

    Skin optical clearing has shown tremendous potential in improving various optical imaging performances, but there is some certain blindness in screening out high-efficiency in vivo optical clearing methods. In this work, three optical clearing agents: sucrose (Suc), fructose (Fruc) and PEG-400 (PEG), and two chemical penetration enhancers: propylene glycol (PG) and thiazone (Thiaz) were used. PEG was firstly mixed with the two penetration enhancers, respectively, and then mixed with Fruc and Suc, respectively, to obtain six kinds of skin optical clearing agents (SOCAs). Optical coherence tomography angiography was applied to monitor SOCAs-induced changes in imaging performances, skin optical properties, refractive index mismatching extent, and permeability rate. Experimental results demonstrated that PEG+Thiaz+Suc has the optimal capacity in enhancing the imaging performances, decreasing the scattering and the refractive index mismatching since Thiaz is superior to PG, and Suc is superior to Fruc. This study indicates that the optimal SOCA can be obtained directly by means of additionally adding or replacing the similar category substance in preexisting SOCAs with some more effective reagents. It not only provides an optimal SOCA, but also provides a useful way to develop more effective SOCAs. Cross-section skin structural texture (a), reconstructed blood flow distribution information (b), before or after treated with different SOCAs.

  7. Effect of different pretreatments on functional properties of African catfish (Clarias gariepinus) skin gelatin.

    PubMed

    See, S F; Ghassem, M; Mamot, S; Babji, A S

    2015-02-01

    Pretreatments with different types of alkali and acid were compared to determine their effects on gelatin extraction from African catfish (Clarias gariepinus) skin. The study was divided into three parts. In the first part, the skins were only treated with alkaline (Ca(OH)2 or NaOH) solution or pretreated with acetic acid solution. For second part, combination of alkali and acid pretreatment was carried out. For the third part, the skins were first treated with NaOH solution, followed by the treatment with acetic acid, citric acid or sulfuric acid solution. Functional properties including the yield of protein recovery, gel strength, viscosity, pH and viscoelastic properties were determined on gelatins obtained with different pretreatment conditions. Pretreatment with alkali removed noncollagenous proteins effectively, whilst acid pretreatment induced some loss of collagenous proteins. Combination of alkali and acid pretreatment not only removed the noncollagenous proteins and caused a significant amount of swelling, but also provided the proper pH condition for extraction, during which some cross-linkages could be further destroyed but with less breakage of intramolecular peptide chains. Pretreatment of catfish skins with 0.2 N NaOH followed by 0.05 M acetic acid improved yield of protein recovery, gel strength, viscosity, melting temperature and gelling temperature of gelatin extract.

  8. Sunscreens: topical and systemic approaches for protection of human skin against harmful effects of solar radiation

    SciTech Connect

    Pathak, M.A.

    1982-09-01

    This review deals with topical and systemic approaches for protection of human skin against the harmful effects of solar radiation. Two concerns about the deleterious effects of sun exposure involve: (1) acute effects (e.g., sunburn and drug-induced phototoxicity) and (2) potential long-term risks of repeated sun exposures leading to development of solar elastosis, keratoses, induction of both nonmelanoma and melanoma skin cancer, and alteration of immune responses and functions. Action spectra of normal and abnormal reactions of human skin to acute and chronic effects of solar radiation are presented with a view to helping the physician prescribe the appropriate sunscreens. Factors that influence acute effects of sunburn are reviewed. Various artificial methods effective in minimizing or preventing harmful effects of solar radiation, both in normal individuals and in patients with photosensitivity-related problems, are discussed. Emphasis is placed on the commercially available chemical sunscreens and their properties. Sun protection factor (SPF) values of several brand-name formulations determined with a solar simulator under indoor conditions (laboratory) and with solar radiation under natural, field conditions are presented. Factors responsible for variations of SPF values observed under indoor and outdoor conditions are reviewed. Systemic photoprotective agents and their limitations are outlined. The photobiology of melanin pigmentation (the tanning reaction) is briefly discussed, with emphasis on the dangers of using quick-tanning lotions for stimulation of the tanning reaction.

  9. The effects of sodium oxybate on core body and skin temperature regulation in narcolepsy.

    PubMed

    van der Heide, Astrid; Donjacour, Claire E H M; Pijl, Hanno; Reijntjes, Robert H A M; Overeem, Sebastiaan; Lammers, Gert J; Van Someren, Eus J W; Fronczek, Rolf

    2015-10-01

    Patients suffering from narcolepsy type 1 show altered skin temperatures, resembling the profile that is related to sleep onset in healthy controls. The aim of the present study is to investigate the effects of sodium oxybate, a widely used drug to treat narcolepsy, on the 24-h profiles of temperature and sleep-wakefulness in patients with narcolepsy and controls. Eight hypocretin-deficient male narcolepsy type 1 patients and eight healthy matched controls underwent temperature measurement of core body and proximal and distal skin twice, and the sleep-wake state for 24 h. After the baseline assessment, 2 × 3 g of sodium oxybate was administered for 5 nights, immediately followed by the second assessment. At baseline, daytime core body temperature and proximal skin temperature were significantly lower in patients with narcolepsy (core: 36.8 ± 0.05 °C versus 37.0 ± 0.05 °C, F = 8.31, P = 0.01; proximal: 33.4 ± 0.26 °C versus 34.3 ± 0.26 °C, F = 5.66, P = 0.03). In patients, sodium oxybate administration increased proximal skin temperature during the day (F = 6.46, P = 0.04) to a level similar as in controls, but did not affect core body temperature, distal temperature or distal-proximal temperature gradient. Sodium oxybate administration normalised the predictive value of distal skin temperature and distal-proximal temperature gradient for the onset of daytime naps (P < 0.01). In conclusion, sodium oxybate administration resulted in a partial normalisation of the skin temperature profile, by increasing daytime proximal skin temperature, and by strengthening the known relationship between skin temperature and daytime sleep propensity. These changes seem to be related to the clinical improvement induced by sodium oxybate treatment. A causal relationship is not proven.

  10. Amino Acid Availability Regulates the Effect of Hyperinsulinemia on Skin Protein Metabolism in Pigs*

    PubMed Central

    Tuvdendorj, Demidmaa; Børsheim, Elisabet; Sharp, Carwyn P.; Zhang, Xiaojun; Barone, Carrie M.; Chinkes, David L.; Wolfe, Robert R.

    2015-01-01

    The effects of amino acid supply and insulin infusion on skin protein kinetics (fractional synthesis rate (FSR), fractional breakdown rate (FBR), and net balance (NB)) in pigs were investigated. Four-month-old pigs were divided into four groups as follows: control, insulin (INS), amino acid (AA), and INS + AA groups based on the nutritional and hormonal conditions. l-[ring-13C6]Phenylalanine was infused. FBR was estimated from the enrichment ratio of arterial phenylalanine to intracellular free phenylalanine. Plasma INS was increased (p < 0.05) in the INS and INS + AA groups. Plasma glucose was maintained by infusion of glucose in the groups receiving INS. The interventions did not change the NB of skin protein. However, the interventions affected the FSR and FBR differently. An infusion of INS significantly increased both FSR and FBR, although AA infusion did not. When an AA infusion was added to the infusion of insulin (INS + AA group), FSR and FBR were both lower when compared with the INS group. Our data demonstrate that in anesthetized pigs INS infusion did not exert an anabolic effect, but rather it increased AA cycling into and out of skin protein. Because co-infusion of AAs with INS ameliorated this effect, it is likely that the increased AA cycling during INS infusion was related to AA supply. Although protein kinetics were affected by both INS and AAs, none of the interventions affected the skin protein deposition. Thus, skin protein content is closely regulated under normal circumstances and is not subject to transient changes in AAs or hormonal concentrations. PMID:26032410

  11. Synergistic effects of combined phytochemicals and skin cancer prevention in SENCAR mice.

    PubMed

    Kowalczyk, Magdalena C; Kowalczyk, Piotr; Tolstykh, Olga; Hanausek, Margaret; Walaszek, Zbigniew; Slaga, Thomas J

    2010-02-01

    The purpose of our study was to determine the inhibitory effect of combined phytochemicals on chemically induced murine skin tumorigenesis. Our hypothesis was that concurrent topical and dietary treatment with selected compounds would lead to more efficient prevention of skin cancer. We tested ellagic acid and calcium D-glucarate as components of diets, while resveratrol was applied topically; grape seed extract was applied topically or in the diet. The 4-week inflammatory-hyperplasia assay based on the 7,12-dimethylbenz[a]anthracene (DMBA)-induced skin carcinogenesis model in SENCAR mice was used. We have found that all the selected combinations caused a marked decrease of epidermal thickness compared with the DMBA-treated group and also with groups treated with a single compound and DMBA. All combinations of resveratrol with other compounds showed a synergistic effect on hyperplasia and Ha-ras mutations. Skin tissue of mice receiving the combinations showed decreased cell proliferation and Bcl2 expression; decreased p21, a regulator of cell cycle; and decreased marker of inflammation cyclooxygenase-2. All the selected combinations diminished the DMBA-induced mRNA expression of the CYP1B1 level, and also caused a marked decrease of proto-oncogenes c-jun and c-fos, components of transcription factor activator protein. In conclusion, all combinations showed either additive or synergistic effects and their joint actions allowed for decreasing the doses of the compounds. Especially, resveratrol combinations with ellagic acid, grape seed extract, and other phytochemicals are very potent inhibitors of skin tumorgenesis, based on the suppression of epidermal hyperplasia as well as on the modulation of intermediate biomarkers of cell proliferation, cell survival, inflammation, oncogene mutation, and apoptosis.

  12. Anomalous transports in a time-delayed system subjected to anomalous diffusion

    NASA Astrophysics Data System (ADS)

    Chen, Ru-Yin; Tong, Lu-Mei; Nie, Lin-Ru; Wang, Chaojie; Pan, Wanli

    2017-02-01

    We investigate anomalous transports of an inertial Brownian particle in a time-delayed periodic potential subjected to an external time-periodic force, a constant bias force, and the Lévy noise. By means of numerical calculations, effect of the time delay and the Lévy noise on its mean velocity are discussed. The results indicate that: (i) The time delay can induce both multiple current reversals (CRs) and absolute negative mobility (ANM) phenomena in the system; (ii) The CRs and ANM phenomena only take place in the region of superdiffusion, while disappear in the regions of normal diffusion; (iii) The time delay can cause state transition of the system from anomalous →normal →anomalous →normal →anomalous →normal transport in the case of superdiffusion.

  13. Effectiveness of skin absorption of tincture of I in blocking radioiodine from the human thyroid gland

    SciTech Connect

    Miller, K.L.; Coen, P.E.; White, W.J.; Hurst, W.J.; Achey, B.E.; Lang, C.M.

    1989-06-01

    Topical application of tincture of iodine (I) was found to be effective in blocking the thyroid uptake of orally administered /sup 131/I in humans. Abdominal skin application of tincture of I resulted in an approximately 82% reduction in the uptake of /sup 131/I by the thyroid gland. The effectiveness varied among individuals and may have depended on the quantity applied and on the application site. In each study group, elevated levels of serum I were observed.

  14. Origin of the low critical observing temperature of the quantum anomalous Hall effect in V-doped (Bi, Sb)2Te3 film

    DOE PAGES

    Li, W.; Claassen, M.; Chang, Cui -Zu; ...

    2016-09-07

    The experimental realization of the quantum anomalous Hall (QAH) effect in magnetically-doped (Bi, Sb)2Te3 films stands out as a landmark of modern condensed matter physics. However, ultra-low temperatures down to few tens of mK are needed to reach the quantization of Hall resistance, which is two orders of magnitude lower than the ferromagnetic phase transition temperature of the films. Here, we systematically study the band structure of V-doped (Bi, Sb)2Te3 thin films by angle-resolved photoemission spectroscopy (ARPES) and show unambiguously that the bulk valence band (BVB) maximum lies higher in energy than the surface state Dirac point. Finally, our resultsmore » demonstrate clear evidence that localization of BVB carriers plays an active role and can account for the temperature discrepancy.« less

  15. Origin of the low critical observing temperature of the quantum anomalous Hall effect in V-doped (Bi, Sb)2Te3 film

    PubMed Central

    Li, W.; Claassen, M.; Chang, Cui-Zu; Moritz, B.; Jia, T.; Zhang, C.; Rebec, S.; Lee, J. J.; Hashimoto, M.; Lu, D.-H.; Moore, R. G.; Moodera, J. S.; Devereaux, T. P.; Shen, Z.-X.

    2016-01-01

    The experimental realization of the quantum anomalous Hall (QAH) effect in magnetically-doped (Bi, Sb)2Te3 films stands out as a landmark of modern condensed matter physics. However, ultra-low temperatures down to few tens of mK are needed to reach the quantization of Hall resistance, which is two orders of magnitude lower than the ferromagnetic phase transition temperature of the films. Here, we systematically study the band structure of V-doped (Bi, Sb)2Te3 thin films by angle-resolved photoemission spectroscopy (ARPES) and show unambiguously that the bulk valence band (BVB) maximum lies higher in energy than the surface state Dirac point. Our results demonstrate clear evidence that localization of BVB carriers plays an active role and can account for the temperature discrepancy. PMID:27599406

  16. The anomalous memory effect related to the relaxation of surface and core moments observed in well-dispersed CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Huang, S.; Ma, Y. Q.; Xu, S. T.

    2015-12-01

    Well-dispersed uniform cobalt ferrite nanoparticles were synthesized by thermal decomposition of a metal-organic salt in organic solvent with a high boiling point, and characterized by XRD, TEM and detailed magnetic measurements. The moments of CoFe2O4 nanoparticles consist of the core and canted surface moments below 200 K, and the exchange-coupling between the surface and core spins enhanced the remanence (Mr) to saturation (Ms) magnetization ratio (Mr/Ms) at the temperature of 10 K. Interestingly, the anomalous memory effect was observed in a broad temperature range which can be attributed to the relaxation of surface spins below 200 K and the one from the moments of magnetically ordered entity larger than one particle above 200 K.

  17. Electron's anomalous magnetic-moment effects on electron-hydrogen elastic collisions in the presence of a circularly polarized laser field

    SciTech Connect

    Elhandi, S.; Taj, S.; Attaourti, Y.; Manaut, B.; Oufni, L.

    2010-04-15

    The effect of the electron's anomalous magnetic moment on the relativistic electronic dressing for the process of electron-hydrogen atom elastic collisions is investigated. We consider a laser field with circular polarization and various electric field strengths. The Dirac-Volkov states taking into account this anomaly are used to describe the process in the first order of perturbation theory. The correlation between the terms coming from this anomaly and the electric field strength gives rise to the strong dependence of the spinor part of the differential cross section (DCS) with respect to these terms. A detailed study has been devoted to the nonrelativistic regime as well as the moderate relativistic regime. Some aspects of this dependence as well as the dynamical behavior of the DCS in the relativistic regime have been addressed.

  18. Origin of the low critical observing temperature of the quantum anomalous Hall effect in V-doped (Bi, Sb)2Te3 film.

    PubMed

    Li, W; Claassen, M; Chang, Cui-Zu; Moritz, B; Jia, T; Zhang, C; Rebec, S; Lee, J J; Hashimoto, M; Lu, D-H; Moore, R G; Moodera, J S; Devereaux, T P; Shen, Z-X

    2016-09-07

    The experimental realization of the quantum anomalous Hall (QAH) effect in magnetically-doped (Bi, Sb)2Te3 films stands out as a landmark of modern condensed matter physics. However, ultra-low temperatures down to few tens of mK are needed to reach the quantization of Hall resistance, which is two orders of magnitude lower than the ferromagnetic phase transition temperature of the films. Here, we systematically study the band structure of V-doped (Bi, Sb)2Te3 thin films by angle-resolved photoemission spectroscopy (ARPES) and show unambiguously that the bulk valence band (BVB) maximum lies higher in energy than the surface state Dirac point. Our results demonstrate clear evidence that localization of BVB carriers plays an active role and can account for the temperature discrepancy.

  19. Origin of the low critical observing temperature of the quantum anomalous Hall effect in V-doped (Bi, Sb)2Te3 film

    NASA Astrophysics Data System (ADS)

    Li, W.; Claassen, M.; Chang, Cui-Zu; Moritz, B.; Jia, T.; Zhang, C.; Rebec, S.; Lee, J. J.; Hashimoto, M.; Lu, D.-H.; Moore, R. G.; Moodera, J. S.; Devereaux, T. P.; Shen, Z.-X.

    2016-09-01

    The experimental realization of the quantum anomalous Hall (QAH) effect in magnetically-doped (Bi, Sb)2Te3 films stands out as a landmark of modern condensed matter physics. However, ultra-low temperatures down to few tens of mK are needed to reach the quantization of Hall resistance, which is two orders of magnitude lower than the ferromagnetic phase transition temperature of the films. Here, we systematically study the band structure of V-doped (Bi, Sb)2Te3 thin films by angle-resolved photoemission spectroscopy (ARPES) and show unambiguously that the bulk valence band (BVB) maximum lies higher in energy than the surface state Dirac point. Our results demonstrate clear evidence that localization of BVB carriers plays an active role and can account for the temperature discrepancy.

  20. Partial oxidation of step-bound water leads to anomalous pH effects on metal electrode step-edges.

    PubMed

    Schwarz, Kathleen; Xu, Bingjun; Yan, Yushan; Sundararaman, Ravishankar

    2016-06-28

    The design of better heterogeneous catalysts for applications such as fuel cells and electrolyzers requires a mechanistic understanding of electrocatalytic reactions and the dependence of their activity on operating conditions such as pH. A satisfactory explanation for the unexpected pH dependence of electrochemical properties of platinum surfaces has so far remained elusive, with previous explanations resorting to complex co-adsorption of multiple species and resulting in limited predictive power. This knowledge gap suggests that the fundamental properties of these catalysts are not yet understood, limiting systematic improvement. Here, we analyze the change in charge and free energies upon adsorption using density-functional theory (DFT) to establish that water adsorbs on platinum step edges across a wide voltage range, including the double-layer region, with a loss of approximately 0.2 electrons upon adsorption. We show how this as-yet unreported change in net surface charge due to this water explains the anomalous pH variations of the hydrogen underpotential deposition (Hupd) and the potentials of zero total charge (PZTC) observed in published experimental data. This partial oxidation of water is not limited to platinum metal step edges, and we report the charge of the water on metal step edges of commonly used catalytic metals, including copper, silver, iridium, and palladium, illustrating that this partial oxidation of water broadly influences the reactivity of metal electrodes.