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Ferroelectric domain walls are promising quasi-2D structures that can be leveraged for miniaturization of electronics components and new mechanisms to control electronic signals at the nanoscale. Despite the significant progress in experiment and theory, however, most investigations on ferroelectric domain walls are still on a fundamental level, and reliable characterization of emergent transport phenomena remains a challenging task. Here, we apply a neural-network-based approach to regularize local I(V)-spectroscopy measurements and improve the information extraction, using data recorded at charged domain walls in hexagonal (Er0.99,Zr0.01)MnO3 as an instructive example. Using a sparse long short-term memory autoencoder, we disentangle competing conductivity signals both spatially and as a function of voltage, facilitating a less biased, unconstrained and more accurate analysis compared to a standard evaluation of conductance maps. The neural-network-based analysis allows us to isolate extrinsic signals that relate to the tip-sample contact and separating them from the intrinsic transport behavior associated with the ferroelectric domain walls in (Er0.99,Zr0.01)MnO3. Our work expands machine-learning-assisted scanning probe microscopy studies into the realm of local conductance measurements, improving the extraction of physical conduction mechanisms and separation of interfering current signals.

Ferroelectric domain walls are promising quasi-2D structures that can be leveraged for miniaturization of electronics components and new mechanisms to control electronic signals at the nanoscale. Despite the significant progress in experiment and theory, however, most investigations on ferroelectric domain walls are still on a fundamental level, and reliable characterization of emergent transport phenomena remains a challenging task. Here, we apply a neural-network-based approach to regularize local I(V)-spectroscopy measurements and improve the information extraction, using data recorded at charged domain walls in hexagonal (Er0.99,Zr0.01)MnO3 as an instructive example. Using a sparse long short-term memory autoencoder, we disentangle competing conductivity signals both spatially and as a function of voltage, facilitating a less biased, unconstrained and more accurate analysis compared to a standard evaluation of conductance maps. The neural-network-based analysis allows us to isolate extrinsic signals that relate to the tip-sample contact and separating them from the intrinsic transport behavior associated with the ferroelectric domain walls in (Er0.99,Zr0.01)MnO3. Our work expands machine-learning-assisted scanning probe microscopy studies into the realm of local conductance measurements, improving the extraction of physical conduction mechanisms and separation of interfering current signals.

Goldstone modes are massless particles resulting from spontaneous symmetry breaking. Although such modes are found in elementary particle physics as well as in condensed-matter systems like superfluid helium, superconductors, and magnons, structural Goldstone modes are rare. Epitaxial strain in thin films can induce structures and properties not accessible in bulk and has been intensively studied for (001)-oriented perovskite oxides. Here we predict Goldstone-like phonon modes in (111)-strained SrMnO3 by first-principles calculations. Under compressive strain the coupling between two in-plane rotational instabilities gives rise to a Mexican hat-shaped energy surface characteristic of a Goldstone mode. Conversely, large tensile strain induces in-plane polar instabilities with no directional preference, giving rise to a continuous polar ground state. Such phonon modes with U(1) symmetry could emulate structural condensed-matter Higgs modes. The mass of this Higgs boson, given by the shape of the Mexican hat energy surface, can be tuned by strain through proper choice of substrate.

Goldstone modes are massless particles resulting from spontaneous symmetry breaking. Although such modes are found in elementary particle physics as well as in condensed-matter systems like superfluid helium, superconductors, and magnons, structural Goldstone modes are rare. Epitaxial strain in thin films can induce structures and properties not accessible in bulk and has been intensively studied for (001)-oriented perovskite oxides. Here we predict Goldstone-like phonon modes in (111)-strained SrMnO3 by first-principles calculations. Under compressive strain the coupling between two in-plane rotational instabilities gives rise to a Mexican hat-shaped energy surface characteristic of a Goldstone mode. Conversely, large tensile strain induces in-plane polar instabilities with no directional preference, giving rise to a continuous polar ground state. Such phonon modes with U(1) symmetry could emulate structural condensed-matter Higgs modes. The mass of this Higgs boson, given by the shape of the Mexican hat energy surface, can be tuned by strain through proper choice of substrate.

Il saggio discute le origini della ricerca sociale, i suoi sviluppi in rapporto alla teoria sociale e alla storia del pensiero sociologico, alla filosofia della scienza e all'epistemologia della ricerca empirica. Vengono quindi analizzati i diversi metodi di ricerca e le operazioni che compie uno scienziato sociale nel realizzare un progetto di ricerca. Infine, sulla base dei più recenti sviluppi della riflessione teorica sulla ricerca, l'analisi si concentra sul senso attuale e futuro della ricerca sociale.

Il capitolo si propone di: 1) innanzitutto presentare alcuni concetti chiave: sesso, genere, ruoli e identità di genere (paragrafi 1 e 2); 2) poi, offrire alcune riflessioni sul sistema di diseguaglianze che deriva dalle differenze corporee tra donne e uomini (paragrafo 3); 3) infine, sarà preso in esame il senso del differenze di genere nella tarda o post-modernità (paragrafo 4).

ZrB2- and HfB2-based composites contg. 1, 3, and 9 vol.% MoSi2 as sintering aid were densified by spark plasma sintering at temps. ranging from 1700 to 1950, with an applied pressure of 100 MPa. As-received ZrB2 and HfB2 powders were also sintered at temps. in the range of 2100-2200. Fully dense samples were obtained between 1750 and 1850 when MoSi2 was added. As-received ZrB2 powder was sintered to 98% at 2100. The microstructural features were investigated by SEM-EDS technique. SciC was detected in all the doped compns. along with significant amts. of oxide species (Hf/ZrO2 and SiO2). Vickers hardness and fracture toughness were measured by indentation technique on polished sections. The effect of the MoSi2 content on densification, microstructure, and mech. properties is discussed.

Densification of nanocrystalline yttria stabilized zirconia (YSZ) powder with 8 mol% Y2O3, prepared by a glycine/nitrate smoldering combustion method, was investigated by spark plasma sintering, hot pressing and conventional sintering. The spark plasma sintering technique was shown to be superior to the other methods giving dense materials (>= 96%) with uniform morphology at lower temperatures and shorter sintering time. The grain size of the materials was 0.21, 0.37 and 12 mu m after spark plasma sintering, hot pressing and conventional sintering, respectively. Total electrical conductivity of the materials showed no clear correlation with the grain size, but the activation energy for spark plasma sintered materials was slightly higher than for materials prepared by the two other densification methods. The hardness, measured by the Vickers indentation method, was found to be independent on grain size while fracture toughness, derived by the indentation method, was slightly decreasing with increasing grain size., QC 20120305

Densification of nanocrystalline yttria stabilized zirconia (YSZ) powder with 8 mol% Y2O3, prepared by a glycine/nitrate smoldering combustion method, was investigated by spark plasma sintering, hot pressing and conventional sintering. The spark plasma sintering technique was shown to be superior to the other methods giving dense materials (>= 96%) with uniform morphology at lower temperatures and shorter sintering time. The grain size of the materials was 0.21, 0.37 and 12 mu m after spark plasma sintering, hot pressing and conventional sintering, respectively. Total electrical conductivity of the materials showed no clear correlation with the grain size, but the activation energy for spark plasma sintered materials was slightly higher than for materials prepared by the two other densification methods. The hardness, measured by the Vickers indentation method, was found to be independent on grain size while fracture toughness, derived by the indentation method, was slightly decreasing with increasing grain size., authorCount :8

ANKE is a new experimental facility for the spectroscopy of products from proton -induced reactions on internal targets. It has recently been implemented in the accelerator ring of the cooler synchrotron COSY of the Forschungszentrum Jülich (FZ-Jülich), Germany. The device consists of three dipole magnets, various target installatio ns and dedicated detection systems. It will enable a variety of hadron-physics experiments like meson production in elementary proton-nucleon processes and studies of medium modifications in proton-nucleus interactions.

The chemical reaction when fluoride melts penetrate into refractory cell linings was investigated. Study of the phase relations along the sodium-fluoride-mullite composition line showed that coexistent phases below the solidus temperature at about 856 degrees C were sodium fluoride, cryolite, nepheline and alpha- or beta-alumina. At more than 20 mole% mullite, first sodium fluoride and later nepheline and cryolite disappeared and only a glassy phase and alpha-alumina were observed. It is suggested that fluoride-rich melts in the NaF-Na3AlF6-NaAlSiO4 system represent the composition of the lining-penetrating bath. The solubility of nepheline in this melt, and therefore its viscosity, increases as acidity is increased by mineral formation during the attack on the lining. The acidic fluoride melts initiate the formation of vitreous, Si-containing phases which strongly reduce further penetration., The chemical reaction when fluoride melts penetrate into refractory cell linings was investigated. Study of the phase relations along the sodium-fluoride-mullite composition line showed that coexistent phases below the solidus temperature at about 856 degrees C were sodium fluoride, cryolite, nepheline and alpha- or beta-alumina. At more than 20 mole% mullite, first sodium fluoride and later nepheline and cryolite disappeared and only a glassy phase and alpha-alumina were observed. It is suggested that fluoride-rich melts in the NaF-Na3AlF6-NaAlSiO4 system represent the composition of the lining-penetrating bath. The solubility of nepheline in this melt, and therefore its viscosity, increases as acidity is increased by mineral formation during the attack on the lining. The acidic fluoride melts initiate the formation of vitreous, Si-containing phases which strongly reduce further penetration.

Autopsies of six spent potlinings with different carbon cathode block grades, amperage regimes and cell designs were conducted at three separate smelters to reveal possible mechanisms causing cathode wear. The microstructure of the cathode samples from the autopsies was investigated by optical and electron microscopy and X-ray computed tomography, while the composition of the solid bath at the surface and in the interior pores was investigated by X-ray diffraction and electron microscopy. The present findings revealed that the cathode surface was characterised by a wear pattern resembling pitting corrosion, and it is discussed that the observed variations in the bath chemistry play a major role in the wear mechanism and the pitting of the surface. A hypothesis involving initiation and termination of the main reaction causing the cathode wear is proposed based on the effect of the consumption of aluminium fluoride in the molten bath layer between the carbon and the molten aluminium pad, resulting in partial solidification of the bath and spatial variation of the current density. (Authors.), Autopsies of six spent potlinings with different carbon cathode block grades, amperage regimes and cell designs were conducted at three separate smelters to reveal possible mechanisms causing cathode wear. The microstructure of the cathode samples from the autopsies was investigated by optical and electron microscopy and X-ray computed tomography, while the composition of the solid bath at the surface and in the interior pores was investigated by X-ray diffraction and electron microscopy. The present findings revealed that the cathode surface was characterised by a wear pattern resembling pitting corrosion, and it is discussed that the observed variations in the bath chemistry play a major role in the wear mechanism and the pitting of the surface. A hypothesis involving initiation and termination of the main reaction causing the cathode wear is proposed based on the effect of the consumption of aluminium fluoride in the molten bath layer between the carbon and the molten aluminium pad, resulting in partial solidification of the bath and spatial variation of the current density. (Authors.)

Existing magnetic separators can only differentiate particles into highly magnetic, middlings and tails, more refined classification being achieved by applying the process repeatedly. A new magnetic separator-classifier has been developed which achieves classification by means of a unique geometry and configuration. The fundamental characteristic is the relationship between the funnel configuration of the static or rotating trunk and the radial concentric magnetic field configuration generated by a superconducting magnet. Magnetic particles injected tangentially on the surface of the trunk suffer a magnetic force in the opposite direction to the acting centrifugal force. Particles with a higher magnetic susceptibility descend, approaching the centre of the trunk and undergoing increasing magnetic force which makes them fly towards the centre at different levels. A prototype device is under construction. Two potential applications are the separation and classification of different magnetic species by their material constitution and the classification of minerals with the same chemical nature by their degrees of purity., Existing magnetic separators can only differentiate particles into highly magnetic, middlings and tails, more refined classification being achieved by applying the process repeatedly. A new magnetic separator-classifier has been developed which achieves classification by means of a unique geometry and configuration. The fundamental characteristic is the relationship between the funnel configuration of the static or rotating trunk and the radial concentric magnetic field configuration generated by a superconducting magnet. Magnetic particles injected tangentially on the surface of the trunk suffer a magnetic force in the opposite direction to the acting centrifugal force. Particles with a higher magnetic susceptibility descend, approaching the centre of the trunk and undergoing increasing magnetic force which makes them fly towards the centre at different levels. A prototype device is under construction. Two potential applications are the separation and classification of different magnetic species by their material constitution and the classification of minerals with the same chemical nature by their degrees of purity.

Differential magnetic classification is defined as the ability to classify a range of magnetic particles into classes of magnetic susceptibility, as opposed to selective magnetic separation of a single magnetic particle type from all others. The attempts to achieve some sort of magnetic classification are reviewed and the first optimised magnetic separator and classifier is briefly described. A number of factors are critical: particle radius must have no influence or negligible influence on outcome; particle trajectories must be as perpendicular as possible to the direction of field gradient increase until the particles are classified; the magnetic force must be opposed by a fully controlled force acting in the opposite direction, and another force acting in some other direction must also exist; and the magnetic force must have a long range or the trajectory of particles under the field gradient's influence must be long enough., Differential magnetic classification is defined as the ability to classify a range of magnetic particles into classes of magnetic susceptibility, as opposed to selective magnetic separation of a single magnetic particle type from all others. The attempts to achieve some sort of magnetic classification are reviewed and the first optimised magnetic separator and classifier is briefly described. A number of factors are critical: particle radius must have no influence or negligible influence on outcome; particle trajectories must be as perpendicular as possible to the direction of field gradient increase until the particles are classified; the magnetic force must be opposed by a fully controlled force acting in the opposite direction, and another force acting in some other direction must also exist; and the magnetic force must have a long range or the trajectory of particles under the field gradient's influence must be long enough.

Cathode wear was investigated in a laboratory cell in which the cathode was directly exposed to the electrolyte during electrolysis. The results were evaluated using a 2D stationary finite element simulation of a simplified slotted cathode cross section rotating in the crucible. The wear was shown to be electrochemical in nature and was dependent on the current density, rotation speed and depth of the prefabricated slots in the cylindrical cathodes. The main wear mechanism was related to the formation of aluminium carbide and its dissolution. No wear was observed without polarisation. The rotation of the cathode promoted mass transfer through the electrolyte and enhanced the wear process., Cathode wear was investigated in a laboratory cell in which the cathode was directly exposed to the electrolyte during electrolysis. The results were evaluated using a 2D stationary finite element simulation of a simplified slotted cathode cross section rotating in the crucible. The wear was shown to be electrochemical in nature and was dependent on the current density, rotation speed and depth of the prefabricated slots in the cylindrical cathodes. The main wear mechanism was related to the formation of aluminium carbide and its dissolution. No wear was observed without polarisation. The rotation of the cathode promoted mass transfer through the electrolyte and enhanced the wear process.