bluuebunny/crossref_metadata_2025 huggingface dataset:
Local Characterization of the Diffusion Process during Discontinuous Precipitation: A Review
Authors: Zieba Pawel , Gust Wolfgang
Published: February 2022

The paper summarizes the recent studies on the diffusive mass transport accompanying the discontinuous precipitation (DP). The studies were performed by applying a local characterization of the kinetics of the DP reaction. In order to accomplish this, a technique of the analytical electron microscopy was used to measure the solute concentration profiles left behind the moving reaction front of single cells. Such an approach, combined with the information on the local values of the lamella thickness and growth rate of the cell, enabled for the first time the determination of local values of the grain boundary diffusivity in the systems Al–Zn, Ni–Sn, Cu–In, Ni–In and Co–Al. The obtained values were comparable to those resulting from the use of the global treatment of the diffusion problem for the DP reaction and the data on the radiotracer diffusion along stationary grain boundaries. This clearly indicates that there is no difference in the rate of diffusion along stationary and moving grain boundaries.
The Dependence of Abnormal Grain Growth on Initial Grain Size in 316 L Stainless Steel
Authors: Lee Sang-Hyun , Choi Jeong Sik , Yoon Duk Yong
Published: February 2022

When 316 L stainless steel specimens are compressed to 30% and annealed at 1300 °C, primary recrystallization rapidly occurs and grains grow normally during further annealing treatment. Thus by annealing for various periods at 1300 °C, specimens with varying average sizes with identical normalized grain size distributions are obtained. When these specimens are heat-treated again at temperatures below 1150 °C, abnormal grain growth (AGG) occurs depending critically on the initial grain size.With decreasing initial grain size, AGG begins earlier during the heat-treatment, and if the initial grain size is large, only slow grain growth occurs without any distinct AGG for periods up to 48 and 96 h. It is observed that AGG occurs by faster growth of large grains with their velocities expected to increase nonlinearly with the driving force arising from the size difference. Because the AGG structure develops gradually, there is not really a well defined incubation time. With the same initial grain size the initiation ofAGGis slower at lower temperatures. A step heat-treatment experiment shows that if there are large grains embedded in the matrix of fine grains, they can grow abnormally under the condition where no AGG occurs with a narrow grain size distribution. The extremely slow grain growth with initially large average grain sizes is attributed to the low grain boundary velocity limited by the boundary step nucleation or growth. It is proposed that the same boundary step mechanism is qualitatively consistent with abnormal growth of the large grains with singular grain boundaries at low temperatures.
Evaluation of Densification Mechanisms of Liquid-Phase Sintering
Authors: Lee Sung-Min , Kang Suk-Joong L.
Published: February 2022

The contact flattening between grains has long been considered to be the densification mechanism during liquidphase sintering. Recently, however, we proposed pore filling as being the major mechanism. In this investigation, we critically examine the two densification mechanisms by calculating their contributions to the sintering. The calculation shows that the contact flattening can be operative at the early stage for systems with a dihedral angle of zero degrees. However, its contribution to grain shape change and compact shrinkage is insignificant compared with that of the grain growth. A consideration of microstructures in real systems further suggests that the contribution of contact flattening is much less than the calculated value and is negligible from the beginning of the liquid-phase sintering. In fact, pore filling, which is induced by grain growth, appears to be essentially the only densification mechanism. An exemplified calculation of densification kinetics by pore filling is also presented and its implication discussed.
Phase Transformation of a Dual Phase Al–Fe Alloy Prepared by Mechanical Alloying
Authors: Zhou Fei , Lück Reinhard , Lu Ke , Rühle Manfred
Published: February 2022

A metastable Al90Fe10 (at.%) alloy, composed of a supersaturated solid solution of face-centred cubic (fcc) Al(Fe) and an amorphous phase matrix, was prepared by mechanical alloying of a mixture of Al and Fe elemental blends. The thermally induced microstructural evolution in the dual phase alloy was characterized by X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, and magnetothermal analysis. On continuous heating two stages of solid state phase transformation occurred: (i) a polymorphous crystallization of the amorphous phase to a metastable crystalline Al6Fe that structurally stabilizes over a temperature range of about 200 K, and (ii) a eutectoid decomposition of the crystalline Al6Fe into the equilibrium phases of Al13Fe4 and fcc Al(Fe). Thermodynamic and kinetic analyses of the observed phase transformation processes were given. The formation of the dual phase alloy in the as-milled state and the phase transitions can be illustrated by a hypothetical free energy diagram, implying the dual phase structure facilitates the polymorphous crystallization of Al6Fe.
Discrete Element Simulation of Ceramic Powder Processing
Authors: Greil Peter , Cordelair Jens , Bezold Alexander
Published: February 2022

Discrete element modeling (DEM) was applied for simulating the powder packing dynamics during electrophoretic deposition of electrostatically stabilized ZrO2 (powder size 1 μm) and tape casting of BaTiO3 (powder size 0.3 μm) stabilized by polymer adsorption. The results indicate that a transition zone of ordering is supposed to exist ahead of the growth front of the solid sediment during electrophoretic deposition. Local variation of the shear rate in the tape casting process with increasing distance from the blade gives rise for the generation of particle clusters under low shear, and cluster disintegration (shear thinning) under high shear conditions. Thus, DEM simulation provides a detailed insight into local variations of particle interaction processes during consolidation which can be used for optimization of the shaping process of colloidal ceramic powder suspensions.
Strain Relaxation and Internal Friction in the Range of the Glass Transition
Authors: Ege Michael , Ulfert Wolfgang , Kronmüller Helmut
Published: February 2022

For the investigation of structural relaxation near the glass transition quasistatic creep after-effect measurements have been performed on the alloy Zr65Cu17:5Ni10Al7:5 which shows a large stability above the glass temperature T
g. By a separation of anelastic local atomic rearrangements and viscous long-range diffusion processes the thermal activation parameters of both processes could be determined from Arrhenius diagrams. Below T
g = 606 K an activation enthalpy of 2.1 eV and above T
g an activation enthalpy of 5.6 eV has been determined. For a quantitative description of these relaxation phenomena a new dynamic model is developed which takes into account the continuous formation and annihilation of relaxation centers near T
g. From measurements of the internal friction after rapid temperature changes it could be shown that extended relaxation centers present above T
g become instable below T
g and are split up by diffusion processes above 585 K, however, disappear spontaneously below 580 K.
Epitaxial Growth of Metals on (100) SrTiO3: The Influence of Lattice Mismatch and Reactivity
Authors: Wagner T. , Polli A. D. , Richter G. , Stanzick H.
Published: February 2022

The model system Me/(100) SrTiO3 (Me: Pd, Pt, Cu, Ni, Cr, Mo, Nb, and Al) was used to show that there exists a simple correlation between the formation of particular epitaxial orientations, the lattice mismatch between metal and SrTiO3, and the oxygen affinity of the metal. The growth of the metal films on the (100) SrTiO3 surface was studied by reflection high-energy electron diffraction. Most metals (Pd, Pt, Ni, Nb and Al) grew with the following epitaxial orientation relationship on the SrTiO3: (100) SrTiO3 | | (100) Me, [001] SrTiO3 | | [001] Me. A second epitaxial orientation relationship was detected for Cr and Mo: (100) SrTiO3 | | (100) Cr, Mo, [001] SrTiO3 | | [011] Cr, Mo. For Mo, this orientation was detected only at very high growth temperatures. For each of the epitaxial orientation relationships, the substrate and film planes of four fold symmetry were parallel. Besides the second epitaxial orientation relationship, a third epitaxial orientation relationship was detected for Mo at growth temperatures below 900 K: (100) SrTiO3 | | (110) Mo, [001] SrTiO3 | | [001] Mo. In contrast to all other metals under investigation, Cu grew with a (111) fiber texture on the (100) SrTiO3 surface. The appearance of the first two epitaxial orientation relationships can be interpreted with a simple relationship between the metals’ oxygen affinities and the lattice mismatches with SrTiO3. This relationship can be used for other metals to predict epitaxy on the (100) SrTiO3 surface.
Metastable Al–Nd–Ni and Stable Al–La–Ni Phase Equilibria
Authors: Gödecke Tilo , Sun Wensheng , Lück Reinhard , Lu Ke
Published: February 2022

Fast cooling leads to the formation of metastable phase equilibria in the Al-rich part of the Al –Nd –Ni system. The metastability is characterized by a suppressed formation of the ternary τ
1 phase. The stable Al –La – Ni system is similar to the Al –Nd– Ni system but without the existence of a τ
1 phase. For comparison, this system is investigated. The results are represented as isopleths, liquidus surface projections, and reaction schemes. A fine-grain ternary eutectic morphology with enhanced hardness can be produced by rapid cooling in both ternary systems; the ideal chemical composition of this morphology depends on the cooling rate.
Calculation of Phase Equilibria in Candidate Solder Alloys
Authors: Kattner Ursula R. , Handwerker Carol A.
Published: February 2022

New solder alloys are being developed for electronic assemblies as replacements for traditional Pb-containing solder materials as a result of international pressure to remove Pb from the waste stream. In the transition period from Pb-containing to Pb-free solder alloys, component leads and copper interconnections on circuit board will continue to be pre-tinned with a Pb-containing solder to improve solderability. Phase equilibria information is needed for the evaluation of candidate Pb-free solder alloys in terms of their melting behavior and of the possible effects of Pb-contamination on manufacturing and reliability. The CALPHAD method of phase equilibria calculation using thermodynamic descriptions from databases provides a powerful tool for obtaining such information. The reliability of the calculation, however, depends on the quality of the thermodynamic descriptions of the individual phases. Criteria for the evaluation of these descriptions and the available thermodynamic databases are discussed. The effect of Pb-contamination on four solder alloys is analyzed.
Delaminating Layered Oxide Composites with Wavy Interfaces
Authors: Chen I.-W. , Winn E. J.
Published: February 2022

Two-phase zirconia/porous alumina layered composites with a variety of microstructures and good damage tolerance have been fabricated. The flatness of the layer microstructure can be controlled by deformation processing in the green state when the constituent ceramic powders are suspended in a fluid medium. Mismatch in deformation resistance leads to flow localization creating wavy layers without long-range coherence. Repeated folding and pressing further allows large deformation strains to accumulate and thin layers to be obtained. Under flexural loading, very high nominal strains can be sustained by successive layer fracture and delamination at the alumina-to-zirconia interface. Compared to conventional flat-layer laminates, these composites are attractive in view of their relative processing ease and their good mechanical performance.
Contemporary Materials Issues for Advanced EB-PVD Thermal Barrier Coating Systems
Authors: Leyens C. , Schulz U. , Fritscher K. , Bartsch M. , Peters M. , Kaysser W. A.
Published: February 2022

The key issues for thermal barrier coating (TBC) development are high temperature capability and durability under thermal cyclic conditions as experienced in the hot section of gas turbines. Due to the complexity of the system and the interaction of the constituents, performance improvements require a systems approach. However, there are issues closely related to the ceramic top coating and the bond coat, respectively. Reduced thermal conductivity, sintering, and stresses within the ceramic coating are addressed in the paper as well as factors affecting failure of the TBC by spallation. The latter is primarily governed by the formation and growth of the thermally grown oxide scale and therefore related to the bond coat. A strategy for lifetime assessment of TBCs is discussed.
Effect of Copper Line Geometry and Process Parameters on Interconnect Microstructure and Degradation Processes
Authors: Zschech Ehrenfried , Blum Werner , Zienert Inka , Besser Paul R.
Published: February 2022

The atomic transport processes which could cause degradation mechanisms in Cu interconnects are described. The influence of interconnect line width, barrier type and anneal process on the microstructure and reliability of the inlaid Cu lines are discussed. Grain size and texture measurements have been performed at blanket films and at arrays of Cu lines using advanced analytical techniques. The median grain size decreases with decreasing line width, and it can be influenced by heat treatments. The crystallographic texture is predominantly {111} out-of-plane with sidewall-oriented grains in narrow Cu lines. The grains have an in-plane preferred orientation with the 〈110〉 direction parallel to the sidewall normal. The Cu texture is influenced by barrier structure and thickness.
Prediction of Local Strain and Hardness in Sheet Forming
Authors: Thomas Sven , Müller Clemens , Exner Eckart
Published: February 2022

A simulation procedure to predict local deformation and properties in deep drawing and other sheet forming processes has been developed, and model experiments were performed to verify the predicted local strain after various ways and degrees of deformation. A strip of aluminium alloy sheet was pulled through a gap between a die and a punch, and bent around a rounded edge and bent back again. Local strains in a cross section of the sheet were estimated from hardness values measured before and after bending by using the hardness – strain relationship obtained for the alloy from tests carried out in tension and compression and with alternating deformation. The finite element (FE) model using ABAQUS was adjusted to the experimental set-up as closely as possible. The agreement between predictions and experiments is in the range of experimental scatter and the general trends are excellently reproduced. However, the precision of hardness measurements is not high enough to check the reliability of the numerical predictions in detail.
Interplay between chemical and magnetic roughness of Pt in a Pt/Co bilayer investigated with X-ray resonant magnetic reflectometry
Authors: Geissler J. , Goering E. , Weigand F. , Schütz G.
Published: February 2022

The magnetization depth profiles of Pt have been investigated by X-ray resonant magnetic reflectivity measurements of sputtered Pt/Co bilayer systems with different chemical roughness values at the Pt/Co interface. The asymmetry ratio as a function of the angle of incidence has been measured at the Pt L3 near-edge absorption region at the maximum of the X-ray magnetic circular dichroism effect. The observed asymmetry ratios in the order of 0.5% are described quantitatively on the basis of a magnetically modified optical approach. The curves of the extracted magnetization profiles in the Pt layer show a different behavior corresponding to chemical roughness, while the magnetic saturation moment of Pt at the Pt/Co interface remains unaltered.
Thermal stability and magnetic anisotropy dispersion in high-density hard-disk media
Authors: Papusoi Cristian , Suzuki Takao
Published: February 2022

A method to correct the anisotropy field distribution for granular recording media, measured by switching methods (isothermal remanent magnetization (IRM) and direct-current demagnetisation (DCD) processes were used as an example) for the effects of thermal relaxation, that supposes an a priori knowledge of the grain size distribution, is presented. For a hard-disk medium, it is shown that the anisotropy field distribution is much narrower (about one order of magnitude) with respect to the grain size distribution. The anisotropy field value estimated from the dependence of the remanence coercivity on the field application time is found in agreement (to within less than 10 %) with the most probable value of the anisotropy field distribution.
Magnetic relaxation in nanocrystalline systems: linking Monte Carlo steps with time
Authors: Vargas P. , Knobel M. , Altbir D.
Published: February 2022

The magnetic relaxation of a noninteracting two-dimensional ensemble of magnetic nanoparticles is simulated as a function of temperature using a Monte Carlo technique. By properly fitting the decay of magnetization using real parameters it is possible to make, at any finite temperature, a clear correspondence between Monte Carlo steps and time measured in seconds. The results allow one to visualize the intrinsic problems related to the simulation of nonequilibrium systems, and to understand the limits and range of validity of a particular system.
Effect of domain size on the magneto-elastic damping in amorphous ferromagnetic metals
Authors: Herzer Giselher
Published: February 2022

We show that the damping of longitudinal mechanical oscillations in soft magnetic amorphous ribbons can be significantly reduced by domain refinement. The latter is realized by an out-of-plane anisotropy induced by magnetic field annealing. The phenomena is interpreted in terms of micro eddy currents associated with the magnetization process within a domain.
Magnetic relaxation phenomena in cobalt
Authors: Blythe H.J.
Published: February 2022

The magnetic relaxation spectrum of polycrystalline, unirradiated Co has been investigated from 4 to 700 K. Both polycrystalline and single-crystal hexagonal close-packed Co have also been investigated after 3 MeV electron irradiation at either 8 or 40 K to doses of 1023 m–2. For unirradiated Co, results are interpreted as due to interactions between dislocations and domain walls. After irradiation at 8 K, relaxation peaks occur in the range 10 –50 K due to the re-orientation of Frenkel pairs which stabilise at the start of the stage-I anneal; a relaxation at 75 K is attributed to an intrinsic interstitial trapped at interstitial carbon. On anneal in the range 220 – 400 K, low-temperature relaxations evolve in samples containing impurities; these are attributed to reorientation of the migrating stage-III defects trapped at impurities.
Effect of rare-earth metals on the hot strength of HSLA steels
Authors: Cabrera José María , Mejía Ignacio , Prado José Manuel
Published: February 2022

An experimental study was done on the effect of rare-earth metals on a high-strength low-alloy steel. The work was focused in deriving the influence on Ce and La on the hot-working behavior. For this purpose, uniaxial hot-compression tests were carried out in a wide range of temperatures and strain rates. The effect of the rare-earth metals was determined by comparison of the characteristic parameters, describing the constitutive equations of the high-temperature response of the steel with, and without, rare-earth metals. The results showed that rare-earth metals were playing a major significant role on hardening mechanisms rather than on softening by dynamic recovery. On the contrary, rare-earth metals were able to delay the onset of dynamic recrystallization. All the present experimental results suggested that the latter roles are played by solid solution strengthening, through a solute drag effect, and not by precipitated particles.
Wear behaviour of Ni–Cr–Mo–V steel under dry sliding
Authors: Pathak J. P. , Mohan S.
Published: February 2022

Dry-sliding wear behaviour of bainitic structure (BS) and tempered martensitic structure (TMS) of Ni–Cr–Mo–V steels have been investigated at room temperature, using a pin-on-disc wear testing rig. These two microstructures reveal the rising trend of wear rate with normal applied load and sliding velocities in the initial stages; but once a maxima is attained in wear rate, then wear rate decreases with further increase in applied load or sliding velocity. It is also observed that wear resistance of TMS steel is superior to BS steel, but the difference in wear rate is not significant. The stereo-micrographs of debris generated show the oxidative and metallic modes of wear for both the microstructures. The study of worn surface clearly highlights the oxide formation, smearing of surface and distortion associated with straining and plastic deformation. The micro-ploughing, spalling and subsequent detachment of oxides and metallic surface layers from the worn-out surface of the pin specimen are the dominant mechanisms of the wear under different conditions of applied loads and sliding velocities. The wear rate is very much influenced by the yield strength and hardness of the bainitic and tempered martensitic steels.
Peritectic equilibrium in Fe-Co alloys
Authors: Sumida Masaki , Kurz Wilfried
Published: February 2022

Recent results of directional solidification experiments with Fe–Co alloys were not consistent with the presently accepted peritectic phase diagram. Therefore, the Fe-rich part of this phase diagram was re-examined. High-temperature gradient plane front solidification was carried out at a low velocity. After quenching of the specimen from the peritectic temperature, the compositions of the phases close to the solid/liquid interface were determined through electron probe microanalysis. Using these results together with previously published phase diagram information, an improved phase diagram is proposed with the peritectic equilibrium at T
p = 1774 K, C
δ = 17.7, C
γ = 18.1 and C
L = 19.5 at.% Co.
Artificial silicide barrier coatings in titanium matrix composites
Authors: Dudek H. J. , Weber K.
Published: February 2022

A continuous S2 silicide ([Ti,Zr]
x
Si
y
) segregation layer was found in the fibre matrix interface of SCS6-SiC/Ti-5.8Al-4Sn-3.5Zr-0.7Nb-0.5Mo-0.35Si (IMI834) composites (composition in wt.%). The S2 layer separates completely the titanium matrix from the reaction layer. It was shown that the S2 layer stabilises the interface during thermal treatment. The thermal stability of composites was tested in which artificial coatings were introduced into the interface. For the artificial coatings a composition and structure of the S2 silicides were aspired. The interface of the composites was investigated with analytical transmission electron microscope in the as-processed condition and annealed at 700 °C for 3 000 h and at 800 °C for 1000 h. The coatings of the same composition and structure can be introduced into the interface of SiC-SCS6/IMI834 composites as those of the S2 silicide obtained by self-segregation. The composites with the artificial coatings have a similar interface stability at 700 °C as those obtained by self-segregation.
Ordering processes and atomic defects in FeCo
Authors: Seeger Alfred
Published: February 2022

The present knowledge on self-diffusion and lattice vacancies in near-stoichiometric body-centred cubic FeCo alloys is critically reviewed and related to the establishment of structural order in the alloy after quenching from elevated temperatures. The available data may be consistently explained in terms of the so-called six-jump cycle mechanism of Huntington, Elcock and McCormick, plus the additional concept of ‘pseudo-selfdiffusivity’. It is shown that this leads to an understanding of the observed combinations of high activation enthalpy and large pre-exponential factor in the Fe self-diffusivity on the one hand, and of a lower activation enthalpy and ‘normal’ pre-exponential factor in the Co self-diffusion on the other hand. For some vacancy properties numerical estimates are given. The potential of muon spin rotation measurements for filling existing gaps in our knowledge is emphasized.

A critical discussion of the “500 °C anomaly” shows that the explanations attempted in the literature are unsatisfactory. It is proposed that the tetragonality of the compounds FeCo3 and Fe3Co predicted by ab-initio calculations of Díaz-Ortiz et al. may lead to a metastable pattern of antiphase domains on a very small scale, the dissolution of which may cause the anomaly.
Electron tomography of microelectronic device interconnects
Authors: Yang Qing , Mardinly John , Kübel Christian , Nelson Chris , Kisielowski Christian
Published: February 2022

As the dimensions of microelectronic devices continue to decrease, single transmission electron microscopy images are not able to properly represent the 3D structures when the structure’s curvature is comparable to the sample thickness. Electron tomography was used to study cylindrical vias coated with Ta-barrier layers and Cu-seed layers in 3D. Tomography reconstructions from both bright field images and high angle annular dark field images are presented. Fidelity of the reconstruction from single-axis and dual-axis tilt series is compared. Strategies for improving the fidelity of the reconstruction and making electron tomography practically applicable for device failure analysis of microelectronic industry are discussed.
Quantitative microstructural and spectroscopic investigation of inversion domain boundaries in sintered zinc oxide ceramics doped with iron oxide
Authors: Walther Thomas , Wolf Frank , Recnik Aleksander , Mader Werner
Published: February 2022

It is known that sintering of powders of zinc oxide (ZnO) with small additions of iron oxide results in a ceramic with grains exhibiting a characteristic inversion domain micro-structure with planar inversion domain boundaries (IDBs) on two different habit planes. This study concentrates on a quantitative analysis, by a combination of different transmission electron microscopy methods, of those IDBs that are parallel to {0001} basal planes of the wurtzite structure of ZnO. Electron diffraction and dark-field imaging prove the nature of the inversion. High-resolution annular dark field scanning transmission electron microscopy allows measurement of the rigid body displacements across these IDBs and of the local lattice contraction related to the octahedral interstices that form the boundaries. Energy-selected imaging, electron energy-loss spectroscopy and energy-dispersive X-ray spectroscopy have been combined to determine the chemical composition of the IDBs quantitatively. It is thus shown unambiguously that every such fault consists of precisely one basal plane of octahedral interstices that are completely occupied by Fe3+ ions and that these FeO6 octahedra are themselves contracted along the <0001> direction. A local charge balance model explains the observations.
Short-range order of liquid Ti72.3Fe27.7 investigated by a combination of neutron scattering and X-ray diffraction
Authors: Holland-Moritz Dirk , Heinen Oliver , Bellissent Robert , Schenk Thomas , Herlach Dieter M.
Published: February 2022

In this work we report on investigations into the topological and chemical short-range order of binary Ti72.3Fe27.7 alloy melts. In order to analyse the structure, the melts were investigated by means of neutron scattering and energy dispersive diffraction of synchrotron radiation. The combination of both diffraction techniques allowed the determination of the partial Bhatia Thornton structure factors S
NN(Q) and S
CC(Q). The experimental results provide evidence of an icosahedral topological short-range order prevailing in the liquid that is accompanied by a pronounced chemical short-range order such that Ti –Fe nearest neighbours are preferentially formed.
Omega phase transformation – morphologies and mechanisms
Authors: Banerjee S. , Tewari R. , Dey G. K.
Published: February 2022

Various morphologies of the ω phase are observed in the α and the β phases of group-IV elements and their alloys where formation of this phase is induced by various means, namely, quenching from the β-phase field, isothermal annealing, under high static as well as dynamic pressure, and irradiation. The presence of various morphologies, such as ellipsoidal, cuboidal, granular or plate shapes, under different conditions is demonstrated. It is shown that various factors, including shuffling of atoms, shearing of atomic planes, long-range diffusion of solute atoms, change in volume during transformation, etc., influence the formation of different morphologies of the ω phase. The underlying mechanisms in each case are discussed. Ordered ω phases, which exist as equilibrium phases in various alloy systems, are shown as a case of superimposition of the concentration wave on the displacement wave.
Annealing-induced phase transitions in a Zr–Ti–Nb–Cu–Ni–Al bulk metallic glass matrix composite containing quasicrystalline precipitates
Authors: Kühn Uta , Eckert Jürgen , Schultz Ludwig
Published: February 2022

The phase formation of a copper-mold-cast Zr60Ti2Nb6Cu14 Ni9Al9 alloy has been investigated upon cooling from the melt as well as upon annealing of as-cast specimens. The different states of the samples are characterized by X-ray diffraction, optical and electron microscopy, and differential scanning calorimetry. The cooling rate as realized upon copper-mold casting leads to micrometer-sized quasicrystals, which are embedded in a glassy phase. The thermal stability ΔTx
of the supercooled liquid state of the glassy phase that forms near to the wall of the copper mold, differs from that of the glassy matrix in the center of the rod due to different compositions of the glassy phase. This is a consequence of the change in local cooling conditions, which affects the phase formation upon solidification as well as the subsequent transformation behavior of the alloy upon constant-rate heating.
Self-induced oscillations in Si and other semiconductors
Authors: Föll Helmut , Carstensen Jürgen , Foca Eugen
Published: February 2022

Some metals share an elusive property with silicon (and other semiconductors): they may exhibit strong self-induced current oscillations during anodic dissolution in electrochemical experiments. While this feature, as well as related features concerning self-organization at reactive solid-liquid interfaces, is still not well understood, the so-called “current-burst model” of the authors succeeded in reproducing many effects quantitatively that have been observed at the Si electrode. The current-burst model assumes that current flow through the electrode on a nm scale is inhomogeneous in both time and space; a single current-burst is a stochastic event. Current oscillations in time and space result from interactions in space or time of single current-bursts. The paper outlines the basics of the model and gives results of Monte Carlo simulations concerning stable and damped oscillations for the current and, as a new feature, for the voltage. With the current-burst model a kind of “nano”-electrochemistry is introduced; its strengths, weaknesses, and possible implications for other electrochemical phenomena and for other materials are briefly discussed.
Growth, interface structure, and magnetic properties of Fe/GaAs and Fe3Si/GaAs hybrid systems
Authors: Herfort Jens , Trampert Achim , Ploog Klaus H.
Published: February 2022

Ferromagnetic Fe and Fe3Si films are grown on GaAs(001) substrates by molecular beam epitaxy. This review article summarizes the important aspects of the heteroepitaxial growth and the associated structural properties of the Fe/GaAs and Fe3Si/GaAs heterostructures. The magnetic anisotropy of the thin Fe epilayers is analyzed and correlated to the interface structure, which is determined by high-resolution transmission electron microscopy. The structural and electrical properties of Fe3Si alloys depend on the exact stoichiometry and the long-range atomic ordering that is controlled by the growth conditions during the molecular beam epitaxy. The interface reactivity and the thermal stability are critically discussed for both heterosystems.
Radiation damage during HRTEM studies in pure Al and Al alloys
Authors: Mingler Bernhard , Karnthaler H. Peter
Published: February 2022

During transmission electron microscopy (TEM) investigations of Al alloys, defects caused by the electron irradiation can occur. Since the image contrast of these irradiation defects is similar to that of early stages of precipitates, care is needed to avoid confusion. In the present paper the formation and the coarsening of radiation damage defects were studied by in situ TEM in both, pure Al and Al alloys. High-resolution (HR)TEM images show on an atomic level that the radiation defects are extrinsic Frank loops (some converted into unfaulted prismatic loops); they are distributed homogeneously within the TEM foil but inhomogeneously on the four {111} planes. Applying HRTEM imaging conditions, the minimum electron energy causing defects is found to be as low as 110 keV using a [110] beam direction. The results for pure Al are very similar to those of the Al alloys. Therefore, during HRTEM studies (using accelerating voltages > 100 kV) the formation of radiation defects seems inevitable; they can be distinguished from the early stages of precipitates if they lie on different planes.
Free-space optical link optimization in visible light communication system
Authors: Ngene Chidi E. , Thakur Prabhat , Singh Ghanshyam
Published: February 2022

Free space optical communication is a potential technology that exploits the visible light frequency band for communication. In this paper, a free-space optical link (FSOL) optimization in visible light communication (VLC) is used to improve the channel performance for signal strength and analyze the effect of signal failures in a communication system. The data transmission and reception phenomenon are established using a light-emitting diode (LED) as a carrier at transmitter and photodiode as a detector at the receiver, respectively. The OptiSystem tool uses to optimize the component parameters of this proposed communication system. The bit error rate (BER) analyzer displays the signals as an eye diagram with the challenges of components uncertainty for better signal performance. The optimized components solve the problem encountered transmitting improve and enhance the signals strength. The acceptable eye diagram displayed from the BER analyzer has been resolved as a result of component optimizations by adding and removing noise to ascertain the behavior of the channel. A better signal retrieve by the display of the acceptable eye diagram from the OptiSystem software used. The FSOL components optimization improve the loss of data, weak signal, loss of power, signal failure, and signal errors which guarantee multi-mobile users with the shared signal. OptiSystem software package used to fully characterize the FSOL system.
COVID-19 and its effect on Instagram adoption by #OBGYN residency programs
Authors: Yadav Ghanshyam S. , Upadhyay Animesh , Welch Jennifer , Kilpatrick Charles C. , Turrentine Mark A.
Published: February 2022

Objectives

Instagram (IG) is becoming one of the larger resource tools within medicine. Since the onset of the COVID-19 pandemic, it is becoming important for programs to improve virtual presence and outreach. We evaluated the adoption of IG by OB/GYN residency programs in the United States and aimed to see if highly ranked programs had higher utilization rates.

Methods

IG presence and engagement metrics were extracted for all ACGME accredited OB/GYN programs. Doximity residency navigator tool was used to obtain nationwide program rankings, and statistical analysis was performed to prove any significant correlation. Mann–Whitney U test, Cochran-Armitage test and Analysis of variance were used for analysis. IRB exemption was obtained.

Results

Seventy percent of programs (202/287) have IG presence, with the majority creating presence after the COVID pandemic began (115/202; 57%). Seventy-two percent (83/115) of these programs created their IG account once virtual interviews were announced. The top 25% of programs, as ranked on Doximity, have a higher number of posts, followers and likes when compared to the rest of the programs.

Conclusions

The COVID-19 pandemic has led to increased adoption of IG by residency programs. Highly ranked and reputed programs have higher rates of activity, popularity, and engagement on IG.
One-dimensional and three-dimensional coupling simulation research of centrifugal cascade hydraulics
Authors: Hao Yan , Jun Che , Siyu Chen
Published: February 2022

Centrifuge cascade hydraulics research is very important for the cascade system design and safety analysis. The one-dimensional centrifugal cascade dynamic hydraulics calculation program can be used to achieve the rapid verification of the cascade system dynamic operation or accident condition. While the computational fluid dynamics (CFD) program is mainly used to analyze the local three-dimensional fluid phenomena such as the centrifugal cascade pipe and equipment. To comprehensively utilize the advantages of the two simulation methods, based on the one-dimensional calculation software SimuWorks of centrifugal cascade hydraulics and three-dimensional flow field calculation software Fluent, a one-dimensional and three-dimensional coupling simulation program for centrifugal cascade hydraulics was developed by using the API functions provided by SimuWorks simulation software and the user-defined function (UDF) of Fluent. The coupling method is used to analyze the movement of solid particles in the main feed pipe of the separation stage. By comparing the calculation results of the coupling program with the calculation results of the traditional one-dimensional dynamic hydraulics program, it can be seen that the coupling program can correctly predict the influence of feeding orifice plate clogging on the system parameters and can more intuitively show the flow field characteristics in the important parts of the system. The motion characteristics of the solid particles obtained in the simulation verification are consistent with the experimental analysis results, which further verifies the accuracy of the coupling program. The coupling program can provide a new calculation method and analytical tool for the study of centrifugal cascade hydraulics.
First record of the elusive and endangered long-tailed nesokia, Nesokia bunnii, in Iran
Authors: Mahmoudi Ahmad , Sajad Jalali Ali , Hafezi Birgani Keramat , Saki Mohammad , Kryštufek Boris
Published: February 2022

We report for the first time the long-tailed nesokia rat, Nesokia bunnii, in Iran. A single female of this rodent killed by a stray dog in the Hoveyzeh marshes was identified as Nesokia bunnii according to its external and craniodental characteristics. With its four pairs of nipples, the collected specimen did not deviate from the condition is seen in Nesokia indica and the genus Bandicota. Here, we provide the first observations on the natural history of this elusive animal. Examination of the stomach contents of the specimen retrieved green plant material. The animal was killed in a marshy site with small pools scattered all around. The entrance to a burrow which was found on the spot was sheltered by dense reed Phragmites australis. We could not confirm an earlier report that N. bunnii constructs floating nests. This record extends the known distribution range of N. bunnii eastwards into the Khuzestan Province, Southwest of Iran.
Domesticating Artificial Intelligence
Authors: Müller Luise
Published: February 2022

For their deployment in human societies to be safe, AI agents need to be aligned with value-laden cooperative human life. One way of solving this “problem of value alignment” is to build moral machines. I argue that the goal of building moral machines aims at the wrong kind of ideal, and that instead, we need an approach to value alignment that takes seriously the categorically different cognitive and moral capabilities between human and AI agents, a condition I call deep agential diversity. Domestication is the answer to a similarly structured problem: namely, how to integrate nonhuman animals that lack moral agency safely into human society and align their behavior with human values. Just like nonhuman animals, AI agents lack a genuinely moral agency; and just like nonhuman animals, we might find ways to train them to nevertheless assist us, and live and work among us – to “domesticate” them, in other words. I claim that the domestication approach does well in explaining many of our intuitions and worries about deploying AI agents in our social practices.
Connections between metabolism and epigenetic modifications in cancer
Authors: Wang Guangchao , Han Jingdong J.
Published: February 2022

How cells sense and respond to environmental changes is still a key question. It has been identified that cellular metabolism is an important modifier of various epigenetic modifications, such as DNA methylation, histone methylation and acetylation and RNA N6-methyladenosine (m6A) methylation. This closely links the environmental nutrient availability to the maintenance of chromatin structure and gene expression, and is crucial to regulate cellular homeostasis, cell growth and differentiation. Cancer metabolic reprogramming and epigenetic alterations are widely observed, and facilitate cancer development and progression. In cancer cells, oncogenic signaling-driven metabolic reprogramming modifies the epigenetic landscape via changes in the key metabolite levels. In this review, we briefly summarized the current evidence that the abundance of key metabolites, such as S-adenosyl methionine (SAM), acetyl-CoA, α-ketoglutarate (α-KG), 2-hydroxyglutarate (2-HG), uridine diphospho-N-acetylglucosamine (UDP-GlcNAc) and lactate, affected by metabolic reprogramming plays an important role in dynamically regulating epigenetic modifications in cancer. An improved understanding of the roles of metabolic reprogramming in epigenetic regulation can contribute to uncover the underlying mechanisms of metabolic reprogramming in cancer development and identify the potential targets for cancer therapies.
TahcoRoll: fast genomic signature profiling via thinned automaton and rolling hash
Authors: Ju Chelsea J.-T. , Jiang Jyun-Yu , Li Ruirui , Li Zeyu , Wang Wei
Published: February 2022

Objectives

Genomic signatures like k-mers have become one of the most prominent approaches to describe genomic data. As a result, myriad real-world applications, such as the construction of de Bruijn graphs in genome assembly, have been benefited by recognizing genomic signatures. In other words, an efficient approach of genomic signature profiling is an essential need for tackling high-throughput sequencing reads. However, most of the existing approaches only recognize fixed-size k-mers while many research studies have shown the importance of considering variable-length k-mers.

Methods

In this paper, we present a novel genomic signature profiling approach, TahcoRoll, by extending the Aho–Corasick algorithm (AC) for the task of profiling variable-length k-mers. We first group nucleotides into two clusters and represent each cluster with a bit. The rolling hash technique is further utilized to encode signatures and read patterns for efficient matching.

Results

In extensive experiments, TahcoRoll significantly outperforms the most state-of-the-art k-mer counters and has the capability of processing reads across different sequencing platforms on a budget desktop computer.

Conclusions

The single-thread version of TahcoRoll is as efficient as the eight-thread version of the state-of-the-art, JellyFish, while the eight-thread TahcoRoll outperforms the eight-thread JellyFish by at least four times.
Converging multi-modality datasets to build efficient drug repositioning pipelines against Alzheimer’s disease and related dementias
Authors: Yin Zheng , Wong Stephen T.C.
Published: February 2022

Alzheimer’s disease and related dementias (AD/ADRD) affects more than 50 million people worldwide but there is no clear therapeutic option affordable for the general patient population. Recently, drug repositioning studies featuring collaborations between academic institutes, medical centers, and hospitals are generating novel therapeutics candidates against these devastating diseases and filling in an important area for healthcare that is poorly represented by pharmaceutical companies. Such drug repositioning studies converge expertise from bioinformatics, chemical informatics, medical informatics, artificial intelligence, high throughput and high-content screening and systems biology. They also take advantage of multi-scale, multi-modality datasets, ranging from transcriptomic and proteomic data, electronical medical records, and medical imaging to social media information of patient behaviors and emotions and epidemiology profiles of disease populations, in order to gain comprehensive understanding of disease mechanisms and drug effects. We proposed a recursive drug repositioning paradigm involving the iteration of three processing steps of modeling, prediction, and validation to identify known drugs and bioactive compounds for AD/ADRD. This recursive paradigm has the potential of quickly obtaining a panel of robust novel drug candidates for AD/ADRD and gaining in-depth understanding of disease mechanisms from those repositioned drug candidates, subsequently improving the success rate of predicting novel hits.
Digital tongue image analyses for health assessment
Authors: Xie Jiacheng , Jing Congcong , Zhang Ziyang , Xu Jiatuo , Duan Ye , Xu Dong
Published: February 2022

Traditional Chinese Medicine (TCM), as an effective alternative medicine, utilizes tongue diagnosis as a major method to assess the patient’s health status by examining the tongue’s color, shape, and texture. Tongue images can also give the pre-disease indications without any significant disease symptoms, which provides a basis for preventive medicine and lifestyle adjustment. However, traditional tongue diagnosis has limitations, as the process may be subjective and inconsistent. Hence, computer-aided tongue diagnoses have a great potential to provide more consistent and objective health assessments. This paper reviewed the current trends in TCM tongue diagnosis, including tongue image acquisition hardware, tongue segmentation, feature extraction, color correction, tongue classification, and tongue diagnosis system. We also present a case of TCM constitution classification based on tongue images.
Commentary: the complex nexus between (im)mobility and translanguaging
Authors: Mazzaferro Gerardo
Published: February 2022

Translanguaging has now become central to a sociolinguistics that foregrounds globalization and mobility as key concepts for grasping human beings’ capacity to engage with and draw on both multiple linguistic – including named languages – and semiotic resources dynamically and in combination for the purpose of meaning-making (García, Ofelia & Wei Li. 2014. Translanguaging: Language, bilingualism and education. New York: Palgrave/McMillan; Li, Wei. 2018. Translanguaging as a practical theory of language. Applied Linguistics 39(1). 9–30). The contributions collected here testify to the growing importance of translanguaging as a theory and practice within contexts of unprecedented mobility, namely educational and work environments, bringing to light processes of circulation of linguistic and semiotic resources across both physical and digital spaces involving the development of communicative practices as well as subjectivities and identities.