bluuebunny/crossref_metadata_2025 huggingface dataset:
Diffusion-Controlled Grain Growth in Liquid-Phase Sintering of W–Cu Nanocomposites
Authors: Lee Jai-Sung , Yu Ji-Hun
Published: February 2022

The kinetics of W grain growth during liquid-phase sintering (LPS) of W-15 – 25 wt.% Cu nanocomposite powder compacts was investigated in terms of microstructural development as well as theWatom diffusion process in liquid Cu. It was found that W grains grew rapidly while maintaining a round shape during LPS at 1623 K, being inversely proportional to the Cu matrix contents. This indicates that the diffusion-controlled Ostwald ripening (DOR) mechanism dominates the growth process in W–Cu nanocomposites. The result of this investigation on the kinetics of W grain growth definitely identifies the occurrence of DOR growth. Namely, the time exponent of the growth equation was close to the value of 3 and the kinetic constant forWgrain growth decreased with decreasing volume fraction of the W solid phase. This is basically due to the fact that the increase of a liquid matrix lengthens the diffusion path, as a result decreasing the growth rate. The diffusivity of the W atoms in liquid copper was calculated from the growth kinetics to be lower within an order of magnitude than the self-diffusion of the liquid atoms. The presence of Watom solubility in liquid Cu, as well as atom diffusivity, is thought to be responsible for diffusion-controlled growth of W grains during LPS of W–Cu nanocomposite powder.
A Thermodynamic Model of an Amorphous Grain Boundary Phase in Liquid-Phase Sintered β-SiAlON Ceramic
Authors: Golczewski Jerzy A. , Seifert Hans J. , Aldinger Fritz
Published: February 2022

Thermodynamic modeling has been developed to explain the apparent stability of an intergranular amorphous phase in the liquid-phase sintered ceramic. The basic postulate has been to consider such a grain boundary phase as a separate phase of the system. An analytic form of the Gibbs energy functions recently derived for amorphous silicates has been taken to describe this boundary phase. A derived equilibrium condition conforming with the construction of parallel tangents to Gibbs energy functions has been used to estimate the compositions of the bulk and of the boundary phase. The microstructure of liquid-phase sintered β-SiAlON ceramic has been ascertained in this way. This model supports the existence of amorphous boundary phases as thermodynamically stable and provides a relation between their amount and the composition of the sinter additives in agreement with the experimental evidence.
Microstructure and Modifications of Cu/Al2O3 Interfaces
Authors: Scheu Christina , Stein Wilhelm , Klein Saskia , Wagner Thomas , Tomsia Antoni P. , Rühle Manfred
Published: February 2022

A combined approach of high-resolution transmission electron microscopy and electron energy-loss near-edge structure studies was employed to determine the atomic structure and bonding mechanisms at Cu/Al2O3 interfaces in dependence on the α-Al2O3 substrate orientation. The investigated specimens were prepared by molecular beam epitaxy using ultrahigh vacuum conditions, which led to atomically abrupt interfaces. The results show that intermetallic Cu–Al bonds occur at the investigated Cu/ (112̅0)Al2O3 interface, while ionic-covalent bonding contributions are observed at the Cu/(0001)Al2O3 interface. The interfacial microstructure of diffusion-bonded Cu/ (0001)Al2O3 samples was changed by annealing treatments under various oxygen partial pressures. Annealing resulted in the formation of a CuAlO2 reaction phase at the interface between Cu and Al2O3.
Structural Transformations Induced by Swift Heavy Ions in Polysiloxanes and Polycarbosilanes
Authors: Pivin Jean-Claude , Pippel Eckhard , Woltersdorf Jörg , Avasthi Devesh Kumar , Kumar Sanjev
Published: February 2022

High-resolution electron microscopy in connection with electron energy filtered microscopy is used for evidencing the precipitation of free C clusters in polysiloxanes and polycarbosilanes, responsible for the hardening and luminescence of these classes of inorganic polymers after ion irradiation. While during irradiation with 3 MeV Au ions randomly distributed carbon clusters are formed, in the case of irradiation with 100 MeVAu ions, the carbon clusters are aligned along tubular ion tracks without forming continuous wires. Contrary to observations in some other polymers and semiconductors, no tubular voids or crystallization of amorphous SiC were found. It is concluded that in both cases the carbon precipitation is due to a solid state transformation induced by electronic excitations.
Phase Equilibria of the Al–Nd and Al–Nd–Ni Systems
Authors: Gödecke Tilo , Sun Wensheng , Lück Reinhard , Lu Ke
Published: February 2022

The Al-rich parts of the Al-Nd and Al-Nd-Ni systems were investigated by thermal and magnetothermal analysis, microstructure, and X-ray analysis. The results are represented as isopleths, isothermal sections, liquidus surface projections, and a reaction scheme.
Thermodynamic Assessment of the Zr–O Binary System
Authors: Liang P. , Dupin N. , Fries S. G. , Seifert H. J. , Ansara I. , Lukas H. L. , Aldinger F.
Published: February 2022

Thermodynamic and phase diagram experimental data relevant to the Zr–O binary system have been assessed. A set of Gibbs energy functions describing the phases in this system is presented. The adjustable parameters of the models are obtained by least-squares fit to the experimental data. The liquid phase is described by Hillert’s partially ionic liquid model. The interstitial solid solution model is applied to the metallic zirconium solid solutions bZr and αZr. The ordering αZr is described by a three-sublattice model with Bragg-Williams treatment of ordering. The two modifications of the zirconium dioxide, αZrO2 and bZrO2, are modelled as stoichiometric phases. The modification cZrO2 is described by the Wagner-Schottky model expressed in the compound-energy formalism. The gas phase is treated as an ideal solution of the species Zr, Zr2,O1, O2, O3, ZrO and ZrO2. The calculated phase diagrams and values for the thermodynamic properties are compared with experimental data.
Thermal Stability of Nanoscale Co/Cu Multilayers
Authors: Bobeth M. , Hecker M. , Pompe W. , Schneider C. M. , Thomas J. , Ullrich A. , Wetzig K.
Published: February 2022

The thermal stability of Co(2 nm)/Cu(2 nm) multilayers, which exhibit the giant magnetoresistance (GMR) effect, has been investigated both experimentally and theoretically. Conventional and analytical transmission electron microscopy, Auger spectroscopy and X-ray analysis revealed changes of the composition on the nanometer scale, the phase morphology as well as the grain structure of multilayers which arise during annealing up to 740 °C. Above an annealing temperature of 300 °C, the onset of grain coarsening accompanied by a transition from a 〈111〉 to a 〈100〉 texture is observed. Moreover, a sharpening of the Co/Cu phase boundaries occurs during annealing up to 600 °C. Transmission electron microscopy observations revealed the coalescence of adjacent Co layers at 600 °C, and a complete disintegration of the layer morphology at 740 °C. Thermally induced changes of the phase morphology were also analysed by means of Monte Carlo simulations. With the assumption that the multilayer decomposition starts by a formation of Cu bridges through Co layers at grain boundaries, simulations of the subsequent evolution of the phase morphology showed a recession of Co layers near grain boundaries which can lead to the localised fusion of adjacent Co layers as well as to a Co and Cu layer thickness coarsening.
Thickness dependence of magnetization structures in thin Permalloy rectangles
Authors: Hertel Riccardo
Published: February 2022

Zero-field magnetization states in Permalloy thin-film elements of rectangular shape are calculated by means of finite element micromagnetic modeling. The energies of several possible magnetization patterns are determined for different sizes and thicknesses of the specimen. Based on these data, a phase diagram of the lowest-energy configuration is set up for rectangles of edge lengths between 250 and 1000 nm. It is shown that a thickness- and size-dependent transition from quasi-homogeneous single-domain states to demagnetized flux-closure patterns occurs in that range. The regime of sizes and thickness of the phase diagram in which the lowest-energy configuration of the thin-film element is a single-domain state is particularly important, since in this case the sample is expected to show good stability with respect to thermal demagnetization, which is a required criterion to make it suitable for technological applications in magneto-electronic devices.
Second-order magnetoelastic effects: From the Dirac equation to the magnetic properties of ultrathin epitaxial films for magnetic thin-film applications
Authors: Fähnle Manfred , Komelj Matej
Published: February 2022

It has always been the endeavour of Professor Kronmüller to combine various methods in order to attain a comprehensive understanding of a physical phenomenon on all relevant scales. In this spirit, we combine the phenomenological nonlinear theory of magnetoelasticity with the relativistic density functional electron theory to describe the magnetoelastic behaviour of epitaxial films. We explain the two already performed cantilever bending beam experiments on the magnetoelasticity and underpin the assumption that second-order magnetoelastic effects are very important for epitaxial Fe films. A complete set of six cantilever experiments is introduced which allows to calculate the intrinsic first- and second-order magnetoelastic constants for cubic materials, and these constants are calculated ab initio for Fe, face-centred cubic Co, Ni, Ni3Fe and CsCl-type CoFe.
The character and role of grain boundaries in NdFeB-type alloys and magnets
Authors: Harris I. R. , Williams A. J.
Published: February 2022

The character and role of grain boundaries in NdFeB alloys and magnets are described and discussed. The role of the grain boundaries in the hydrogen decrepitation process is considered and the influence of the character and mobility of grain boundaries on the properties of fully dense sintered magnets is described. Grain boundaries also play an important role in the hydrogenation disproportionation desorption and recombination process whereby the coarse grain, cast material is converted to very fine grain particles.
Magnetic domain structure and spin reorientation process
Authors: Pastushenkov Yurij G.
Published: February 2022

The domain structure was investigated in the spin reorientation region on the (100) and (001) planes of Nd2Fe14B and R(Fe, Co)11Ti (R = Tb, Dy) single crystals by means of the magnetooptical Kerr effect. The magnetic phase diagram of a tetragonal magnetic crystal was theoretically calculated and the effect of domain structures on phase transitions is investigated. On the basis of the observed domain configurations and domain wall density calculations, possible models for the volume magnetization distributions in tetragonal magnetic crystals with “easy cone” and “easy plane” anisotropy have been discussed.
Magnetic properties of Tb(Fe, Mo)12 and Tb(Fe, Mo)12C compounds
Authors: Rixecker G. , Buschow K. H. J. , Bakker H.
Published: February 2022

Intermetallic compounds in the series TbFe12 – x
Mo
x
, with nominal Mo contents, x, ranging from 1.5 to 3.5, were synthesized and examined for their thermomagnetic properties. Magnetic measurements were performed in the temperature range 5 – 1130 K by using a SQUID magnetometer and a Faraday balance in combination. Synthesis of interstitially carburized TbFe12 – x
Mo
x
C powders by mechanical alloying with graphite and a subsequent heat treatment was attempted for the single-phase compositions between x = 2 and x = 3. The magnetic behavior of the materials (especially the coercivity) shows a number of peculiarities, which we try to explain in terms of crystal chemical and microstructural features.
Metastable alloys at moderate cooling rates
Authors: Stadelmaier Hans H. , Petzow Günter
Published: February 2022

Using examples, old and recent, from the metallurgical literature, we examine the sources of metastable behavior in binary and ternary alloy systems that are subjected to cooling rates in the order of K/min to K/s. Because the metastability invariably involves enhanced unstable or suppressed stable crystalline phases, the key to this behavior must be sought in the crystallization kinetics.
Vacancies in thermal equilibrium and ferromagnetism near the Curie temperature
Authors: Seeger Alfred , Fähnle Manfred
Published: February 2022

In several refractory body-centred cubic metals (α-Fe, V, Nb, Ta) the binding energy of positrons (e+) trapped in vacancies is too small to permit accurate determinations of the enthalpy of formation of monovacancies,H1VF,$ H_{{\rm{1V}}}^{\rm{F}},$by high-temperature positron annihilation. Owing to their larger mass, trapped positive muons (μ+) and π-mesons (π+) are much more firmly bound to vacancies. It is argued that the lattice steering (channelling or blocking) of their charged decay products (e+or μ+) allows us to obtain accurateH1VF$ H_{{\rm{1V}}}^{\rm{F}}$values of the refractory bcc metals. In ferromagnets with high Curie temperaturesTC, such as α-Fe, Co, and FeCo alloys,H1VF$ H_{{\rm{1V}}}^{\rm{F}}$may also be deduced from muon spin rotation (μ+SR) measurements. However, in Fe and Co this approach is limited by the strong sensitivity of the spontaneous magnetization against temperature fluctuations nearTC. The reduction of this sensitivity in the so-called asymptotic critical regime by applying sufficiently strong external magnetic fields is investigated on the basis of the Arrott– Noakes equation. A method for determining the critical amplitudes occurring in this equation is proposed.

In disordered Fe1–xCoxalloys (0.2 ≤x≤ 0.75) the Curie temperatures are sufficiently high for the spontaneous magnetization in the bcc phase not to be critically affected by temperature fluctuations, hence these alloys are well suited for μ+SR investigations of thermal vacancies. From an analysis of the available positron-annihilation and self-diffusion data the vacancy migration enthalpy in disordered Fe0.5Co0.5is found to be (1.1 ± 0.2) eV, in good agreement with quenching data and with the value established for α-Fe.
The vortex lattice in superconductors
Authors: Brandt Ernst Helmut
Published: February 2022

Some properties of the flux-line lattice in conventional and high-T
c superconductors are reviewed, with particular stress on phenomenological theories, nonlocal elasticity, irreversible magnetization curves, and influence of the specimen shape on the electromagnetic response.
A novel technique for measuring diffusivities of short-lived radioisotopes in solids
Authors: Voss Thilo , Strohm Andreas , Matics Stefan , Scharwaechter Peter , Frank Werner
Published: February 2022

After reminding the reader of the major techniques for measuring diffusion coefficients in solids, a detailed description of the conventional radiotracer techniques is presented. These allow to measure solid-state diffusivities in the regime 10– 8–10– 24 m2s– 1 and therefore, and for other reasons to be discussed, are superior to all competing methods. However, the conventional radiotracer techniques suffer from the restriction that they are not applicable to radio-tracer atoms with half-lives t
1/2 ≲ 1 d. The main objective of this paper is to introduce a novel experimental set-up which enables us to perform radiotracer-type diffusivity measurements with short-lived radioisotopes (1 d ≳ t ≳ 10 min). First results on the diffusion of 31Si (t
1/2 = 2.6 h) and 11C (t
1/2 = 20.38 min) in Si–Ge alloys and Si –C–N-based ceramics measured in this set-up are presented.
Hydrogen four-level tunnel systems in substitutional body-centred cubic alloys
Authors: Cordero Francesco , Cantelli Rosario
Published: February 2022

A brief account is provided of the main results of a study of the tunneling states of H trapped by substitutional (S) impurities in Nb, mainly consisting in anelasticity experiments. The phenomenology is rather complex when the concentration of S atoms is higher than a few parts per thousand, and various and contrasting interpretations are possible. The complication arises from the destruction of the symmetry of the S–H pair by the elastic interactions among the defects. The situation becomes, however, clear for an S content around 0.1 %, when the anelastic spectra reveal the relaxation processes due to the now nearly undistorted S–H complexes. In this case H delocalizes over four tetrahedral sites of a face of the cube containing the S atom, giving rise to a four-level tunnel system (FLS). The parameters of tunneling and coupling to phonons and electron excitations are similar to those found for the two-level system of H near an interstitial impurity, but new effects are found, due to the symmetry of the additional eigenstates of a centrosymmetric FLS.
Stability of strengthened niobium alloys in long-term high-temperature loading conditions
Authors: Shyrokov Volodymyr V. , Tcvikilevitch Orest S. , Vasyliv Chrystyna B.
Published: February 2022

Variations in structure and heat resistance of niobium alloys after long-term loading (for up to 10 000 h) in vacuum at 1173 and 1373 K are studied. It is concluded that niobium alloys are more heat-resistant while those undergoing solid-solution hardening are more stable structurally. It is shown that long-term strength plots for niobium alloys have kinks which are to be taken into account when predicting life of structurally unstable materials.
Thermodynamic calculation of the phase diagram of the Co–Nb–Ta system
Authors: Hari Kumar K. C. , Van Rompaey T. , Wollants P.
Published: February 2022

A thermodynamic description of the ternary system Co–Nb–Ta is obtained by combining the descriptions of the lower-order systems according to the CALPHAD method. The thermodynamic data set for the binary Co–Nb system is taken from [1], where a new thermodynamic model for the μ-phase was introduced. The μ-phase appears in several transition metal systems, including Co–Ta. The model is applied to the Co–Ta system and extended to the ternary Co–Nb–Ta system. The thermodynamic descriptions of the systems Co–Ta, Nb–Ta and Co–Nb–Ta are reported in the present work.
Unit cell volumes of the silicon- and germanium-containing solid solutions based on the 3d bcc transition metals
Authors: Ellner M. , Park I.
Published: February 2022

The unit cell parameters and the unit cell volumes were investigated for Si- and Ge-containing solid solutions based on the 3d body-centred cubic transition metals. Excepting the high-temperature solid solution δ-Mn(Si), the solubility of Si increases with increasing number of 3d electrons. In contradiction to the large atomic volume of Si, which is substantially larger than that of the 3d transition metals, the unit cell volume of the terminal solid solutions decreases with increasing Si content. For solid solutions showing a large homogeneity range – α-Fe(Si) and α-Fe(Ge) –, the partial atomic volumes of Si and Ge were evaluated. Comparing the quasihomological Al- and Si-containing solid solutions α-Fe(Al) and α-Fe(Si), the higher bond energy occurs between atoms of Si and Fe than between Al and Fe atoms. Taking into consideration the homology of metalloids in the solid solutions α-Fe(Si) and α-Fe(Ge), the higher bond energy can also be expected between Si and Fe than between Ge and Fe atoms.
Atomic resolution electron tomography: a dream?
Authors: Dyck Dirk Van , Aert Sandra Van , Croitoru Mihail
Published: February 2022

In this paper, the possibilities and intrinsic physical limits to atomic resolution electron tomography are discussed. It is shown that atomic resolution electron tomography is in principle possible and may provide atom position coordinates with sufficient precision to use as input data for theoretical ab-initio calculations. For amorphous materials which are subject to radiation damage it may require a lower voltage and the use of a C
s and C
c corrector. For perfect crystalline samples the projected structure can be reconstructed from exit waves using the channeling theory. Combining the reconstructions obtained from different zone axis orientations then yields the 3D atomic structure. The most difficult objects will be semicrystalline materials where strong dynamic scattering interferes with weak signals from the aperiodicity. Here we suggest to use a new technique called precession laminography. Finally, doubt is raised about the practical usability of optical sectioning by HAADF STEM.
Prospects of the multislice method for CBED pattern calculation
Authors: Kaiser Ute , Chuvilin Andrey
Published: February 2022

We recently showed that the Multisclice method can be used to elucidate the crystal volume contribution to a CBED pattern. Here, we demonstrate in more detail how the directions of each HOLZ line, their Laue zone order, and the specimen thickness determine the volume segment of the Bragg scattering cone of the electron beam and show that secondary rescattering from this volume must take place for deficient line formation in the (000) CBED disk. Moreover, additional prospects of the multislice method are demonstrated such as calculation of line splitting in bent crystals, hollow cone dark-field CBED, large-angle CBED, and whole diffraction patterns including Kikuchi lines.
Quantitative assessment of nanoparticle size distributions from HRTEM images
Authors: Du Kui , Ernst Frank
Published: February 2022

Aiming to determine the size distribution and surface area per unit mass of catalyst nanoparticles for fuel cells, we have developed a novel method of digital image processing that quantitatively determines the size of individual nano-particles from atomic-resolution transmission electron microscopy images. After introducing the basic concept of this new method, we demonstrate its efficiency using platinum nanoparticles on carbon support as a model system. Special attention is given to the error that can be introduced by estimating the surface area per unit mass from the distribution of particle diameters in the presence of asymmetry of the particle size about the mean.
Extended interfacial structure between two asymmetrical facets of a Σ = 9 grain boundary in copper
Authors: Couzinié Jean-Philippe , Thibault J. , Décamps B. , Priester L.
Published: February 2022

The presence of an extended structure in a Σ = 9 grain boundary of copper has been highlighted by high-resolution transmission electron microscopy. The phase, located in a grain boundary region between two different asymmetrical facets, may be described as a three dimensional phase with a hexagonal structure. A detailed analysis of the defects at the limits between the phase and the two copper crystals allows us to propose an interpretation for the occurrence of this local phase transformation.
Wetting of aluminium-based complex metallic alloys
Authors: Belin-Ferré Esther , Dubois Jean Marie
Published: February 2022

Many complex metallic alloys are known to form in aluminium-based systems containing transition metals like Cu, Pd, Fe or Cr, the most famous one being the stable icosahedral quasicrystal discovered in the Al –Cu –Fe system. Although covered by a thin native oxide layer, adhesion of water onto the complex compounds is very different from that onto the oxide or onto oxidised aluminium. We show here how this atypical behaviour is related to the structural complexity of the compound. We then produce data that allows us to estimate the actual surface energy of the same compounds, a property that is also a fingerprint of structural complexity in Al-based intermetallics.
Special planar defects in the structural complex metallic alloys of Al–Pd–Mn and Al–Ni–Rh
Authors: Zhang Ze , Tian He , Chen Yan-Hui , Sun Wei
Published: February 2022

A systematic high-resolution electron microscopy study of a special type of two-dimensional defects, phason planes, has been carried out in the structurally complex metallic alloys of Al –Pd –Mn and Al –Ni –Rh. The structural characteristics of the phason planes in these two alloys consist of pentagon-banana pairs of polygons but with a different arrangement. Located on the vertex of the polygons are pseudo-Mackay atomic clusters. The detailed atomic structures of the phason planes in both ξ′- and ξ-phases of the two alloys have been determined by means of high-resolution electron microscopy and theoretical simulations. The possible ways of displacement of the phason planes in the complex alloys are discussed.
An investigation of improved titanium/titanium nitride barriers for submicron aluminum-filled contacts by energy-filtered transmission electron microscopy
Authors: Rucki Andreas , Robl Werner
Published: February 2022

The adaptation of titanium/titanium nitride barriers which are commonly used for tungsten-filled contacts to aluminum-filled contacts has encountered some limitations. A main issue is the decomposition of titanium nitride manufactured by physical vapour deposition through reaction with aluminum. In this investigation two different concepts for barrier improvement have been pursued: 1. stuffing of a conventional barrier by a rapid thermal process in an oxygen-rich atmosphere and, 2. use of a barrier manufactured by chemical vapour deposition. The aim of the transmission electron microscopic analysis was to explain different electrical breakdown characteristics during thermal stressing of chips with these barriers. Energy-filtered transmission electron microscopy was used to monitor elemental distributions down to nanometer scale. Both concepts are found to improve barriers for aluminumfilled contacts.
Structural properties of the fiber –matrix interface in carbon-fiber/carbon-matrix composites and interfaces between carbon layers and planar substrates
Authors: Gerthsen Dagmar , Bach David , Pauw Virginie De , Kalhöfer Sabine , Reznik Boris , Send Winfried
Published: February 2022

The structure of the fiber –matrix interface region of carbon-fiber/carbon-matrix (C/C)-composites, which is important for the mechanical properties of a composite, was studied by transmission electron microscopy. The pyrolytic carbon matrix was obtained by chemical vapor infiltration of carbon fiber preforms with different fiber architecture and fiber types. While the texture of the carbon matrix can be controlled by the infiltration conditions, the carbon texture at the fiber –matrix interface differs from the bulk matrix and cannot be determined by the infiltration parameters. We often observe a high-textured layer with a thickness up to 100 nm at the interface prior to the formation of the bulk matrix with a lower texture. The fiber –matrix interface properties of C/C-composites are compared with the interface of pyrolytic carbon layers deposited on planar Si-, BN- and cordierite-substrates. In contrast to BN-substrates, thin high-textured pyrolytic layers are observed at the interface of carbon on planar Si- and cordierite-substrates where strong bonding between pyrolytic carbon and the substrate is achieved by the formation of Si-C bonds. Stress-induced ordering is discussed as a mechanism for the formation of the high-textured interface layers.
A proposal for all optical digital multiplexer using photonic crystal-based nonlinear ring resonators
Authors: Geraili Mohammad Reza , Hosseini Seyed Ebrahim , Tavakoli Mohammad Bagher , Shokooh-Saremi Mehrdad
Published: February 2022

For realizing an all optical photonic crystal (PhC)-based Arithmetic Logic Unit (ALU), one needs an optical 4 to 1 digital multiplexer. This device is a logic circuit in which by using two control ports one can connect four input lines to the output port. In this paper we used nonlinear ring resonators combined with optical waveguides to realize an optical digital multiplexer inside two dimensional PhC structure. The final structure was simulated using finite difference time domain method. The simulation results show that the maximum time delay of the final structure is about 3 ps.
Upgrade rate of percutaneously diagnosed pure flat epithelial atypia: systematic review and meta-analysis of 1,924 lesions
Authors: Ferre Romuald , Kuzmiak Cherie M.
Published: February 2022

Context

Management remains controversial due to the risk of upgrade for malignancy from flat epithelial atypia (FEA). Data about the frequency and malignancy upgrade rates are scant. Namely, observational follow-up is advised by many studies in cases of pure FEA on core biopsy and in the absence of an additional surgical excision. For cases of pure FEA, the American College of Surgeons no longer recommends surgical excision but rather recommends observation with clinical and imaging follow-up.

Objectives

The aim of this study is to perform a systematic review and meta-analysis to calculate the pooled upgrade of pure FEA following core needle biopsies.

Methods

A search of MEDLINE and Embase databases were conducted in December 2020. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. A fixed- or random-effects model was utilized. Heterogeneity among studies was estimated by utilizing the I2 statistic and considered high if the I2 was greater than 50%. The random-effects model with the DerSimonian and Laird method was utilized to calculate the pooled upgrade rate and its 95% confidence interval.

Results

A total of 1924 pure FEA were analyzed among 59 included studies. The overall pooled upgrade rate to malignancy was 8.8%. The pooled upgrade rate for mammography only was 8.9%. The pooled upgrade rate for ultrasound was 14%. The pooled upgrade rate for mammography and ultrasound combined was 8.8%. The pooled upgrade rate for MRI-only cases was 27.3%.

Conclusions

Although the guidelines for the management of pure FEA are variable, our data support that pure FEA diagnosed at core needle biopsy should undergo surgical excision since the upgrade rate >2%.
Attributive modification in South American indigenous languages
Authors: Krasnoukhova Olga
Published: February 2022

The article deals with attributive modification in South American languages. It focuses on descriptive terms that denote properties. First of all, it is observed that attributive modification with property terms is possible in most, but not all South American languages. The typology of attributive constructions is argued to constitute a continuum, from syntactically loose nominal expressions, on the one hand, to morphologically complex structures which are ambiguous between compounding and derivation, on the other hand. The latter involves the use of lexico-grammatical means such as classifiers. The paper also raises the question of a possible diachronic link – at least for some languages – between intransitive clauses and postnominal property terms, which are often verbal in nature.
Polygenic risk scores: the future of cancer risk prediction, screening, and precision prevention
Authors: Wang Yuzhuo , Zhu Meng , Ma Hongxia , Shen Hongbing
Published: February 2022

Genome-wide association studies (GWASs) have shown that the genetic architecture of cancers are highly polygenic and enabled researchers to identify genetic risk loci for cancers. The genetic variants associated with a cancer can be combined into a polygenic risk score (PRS), which captures part of an individual’s genetic susceptibility to cancer. Recently, PRSs have been widely used in cancer risk prediction and are shown to be capable of identifying groups of individuals who could benefit from the knowledge of their probabilistic susceptibility to cancer, which leads to an increased interest in understanding the potential utility of PRSs that might further refine the assessment and management of cancer risk. In this context, we provide an overview of the major discoveries from cancer GWASs. We then review the methodologies used for PRS construction, and describe steps for the development and evaluation of risk prediction models that include PRS and/or conventional risk factors. Potential utility of PRSs in cancer risk prediction, screening, and precision prevention are illustrated. Challenges and practical considerations relevant to the implementation of PRSs in health care settings are discussed.
Topological optomechanical amplifier in synthetic
PT

$\mathcal{PT}$

-symmetry
Authors: Zhang Jian-Qi , Liu Jing-Xin , Zhang Hui-Lai , Gong Zhi-Rui , Zhang Shuo , Yan Lei-Lei , Su Shi-Lei , Jing Hui , Feng Mang
Published: February 2022

We propose how to achieve synthetic

PT

$\mathcal{PT}$

symmetry in optomechanics without using any active medium. We find that harnessing the Stokes process in such a system can lead to the emergence of exceptional point (EP), i.e., the coalescing of both the eigenvalues and the eigenvectors of the system. By encircling the EP, both nonreciprocal optical amplification and chiral mode switching can be achieved. As a result, our synthetic

PT

$\mathcal{PT}$

-symmetric optomechanics works as a topological optomechanical amplifier. This provides a surprisingly simplified route to realize

PT

$\mathcal{PT}$

-symmetric optomechanics, indicating that a wide range of EP devices can be created and utilized for various applications such as topological optical engineering and nanomechanical processing or sensing.
Advanced oxidation processes for phthalate esters removal in aqueous solution: a systematic review
Authors: Amiri Hoda , Martinez Susana Silva , Shiri Marziyeh Ansari , Soori Mohammad Mahdi
Published: February 2022

This study addresses a systematic review of the scientific literature to evaluate the most common advanced oxidation processes (AOP) for the removal of phthalate esters (PE) in aqueous matrices. Six AOP were reviewed for PE degradation such as processes based on photolysis, Fenton, ozonation and sulfate radicals (

SO
4

•
−

${\text{SO}}_{4}^{\bullet -}$

), combined AOP and other processes. The PE degradation efficiencies by AOP processes ranged from 40.3 to 100%. In the reviewed literature, an initial PE concentration within 0.04–250 mg/L was applied. The H2O2 concentrations used in the UV/H2O2 process and O3 concentrations in ozonation-based processes ranged between 0.85–1,360.6 mg/L and 2–4,971 mg/L, respectively. Based on the reported results, the PE oxidation data fit well to the pseudo-first order kinetic model. A review of the studies revealed that many oxidant species are produced in the AOP, including hydroxyl radicals (•OH),

SO
4

•
−

${\text{SO}}_{4}^{\bullet -}$

, superoxide radical anions (

O
2

−
•

${\text{O}}_{2}^{-\bullet }$

), hydroperoxyl radicals (HO2
•), hydrogen peroxide (H2O2), and singlet oxygen (O2). Among these oxidants, •OH play a key role in the degradation of PE. However,

SO
4

•
−

${\text{SO}}_{4}^{\bullet -}$

are more effective and efficient than •OH since

SO
4

•
−

${\text{SO}}_{4}^{\bullet -}$

has a higher oxidation power (E = 2.5–3.1 V) compared to •OH radicals (E = 1.8–2.7 V). In different AOP processes, the aromatic rings of PE are destroyed by •OH and produce intermediates such as phthalic acid (C6H4(CO2H)2), benzoic acid ethyl ester (C9H10O2), 2, 5-dihydroxybenzoic acid (C7H6O4), formic acid (CH2O2), acetic acid (CH3COOH), and oxalic acid (C2H2O4), among some others. Until now, limited data have been reported on PE toxicity assessment. The reviewed literature has shown that AOP can be used effectively to degrade PE from aqueous matrices. However, this systematic study suggests focusing more on the evaluation of the toxicity of the effluent resulting from AOP for the decomposition of PE in future studies.
La2FSeTaO4: lanthanum fluoride selenide oxotantalate or lanthanum fluoride oxoselenotantalate?
Authors: Buyer Constantin , Grossholz Hagen , Schleid Thomas
Published: February 2022

Following up the recently reported example La3F2Se2TaO4, colorless needle-shaped single crystals of the new compound La2FSeTaO4 were obtained as an unexpected by-product from solid-state reactions between lanthanum metal, lanthanum trifluoride, lanthanum sesquioxide and selenium in a sodium-chloride flux designed to yield lanthanum oxide fluoride selenides. Silica-jacketed tantalum capsules served as reaction containers at 850 °C, but an undesired activation of the metal tubes led to the formation of a new oxotantalate. La2FSeTaO4 crystallizes orthorhombically in the space group Pnma with the lattice parameters a = 1146.51(6), b = 395.16(2) and c = 1281.32(7) pm for Z = 4. The crystallographically unique Ta5+ cations are surrounded by five oxygen atoms as square pyramids [TaO5]5–, which share trans-oriented vertices (d(Ta–O4) = 202 pm, 2×) to form straight

∞
1

Ta

O
1
,
2
,
3

3
/
1

t

O
4

2
/
2

v

3
−

${}_{\infty }^{1}\left\{{\left[\text{Ta}{\left.\text{O}1,2,3\right.}_{3/1}^{t}{\left.\text{O}4\right.}_{2/2}^{v}\right]}^{3-}\right\}$

chains propagating along [010] with isotactically aligned tips (d(Ta–O1) = 183 pm). Embedded into a matrix of lanthanum fluoride selenide according to

∞
3

La
2

FSe

3
+

${}_{\infty }^{3}\left\{{\left[{\text{La}}_{2}\text{FSe}\right]}^{3+}\right\}$

(d(La–F) = 236–244 pm, d(La–Se) = 312–318 pm), which consists of two different La3+ cations as well as singular F− and Se2− anions, via La–O contacts (d(La–O) = 247–274 pm), the coordination number of the La3+ cation towards the anions F−, O2− and Se2–amounts to nine with tricapped trigonal prisms or capped square antiprisms as coordination polyhedra models. The tantalum cation has a distant contact with a Se2− anion (d(Ta⋯Se) = 317 pm), not efficiently counting to its first coordination sphere, but completing it to a quasi-octahedron.
China in 2021
Authors: Ye Min
Published: February 2022

The year 2021 saw unceasing power concentration in China and inside the ruling Communist Party. China persisted with a zero-COVID policy, but at considerable social and economic costs. The investigation of the origins of the pandemic triggered new sparring between China and Western countries. US–China relations continued to sour as the Biden administration kept on with most of the existing China policies and started building a new security network in the Indo-Pacific region. China tightened its control of Hong Kong’s political life, but its effort toward “complete reunification” faced strong resistance across the Taiwan Strait.
Japan in 2021
Authors: Liff Adam P.
Published: February 2022

For Japan in 2021, COVID-19-related disruption was again the dominant storyline. Its impact transcended societal consequences to affect Japan’s economy, politics, and foreign affairs. It frustrated Japan’s economic recovery and, for the second time in as many years, contributed to a prime minister’s premature resignation. Yet the year also witnessed major positive developments, including the “2020” Tokyo Olympics/Paralympics; an (eventually) successful vaccine rollout; public health outcomes vastly better than those of any other G7 member; an expected return to economic growth; and a smooth national election. On October 31, new prime minister Kishida Fumio led the ruling LDP–Komeito coalition into Japan’s first general election since 2017. Despite losing a few seats, it retained a comfortable lower-house majority, ensuring that a subplot for Japan in 2021 was—again—relative continuity in national politics and foreign affairs.
South Korea in 2021
Authors: Chang Woo-young , Yun Seongyi
Published: February 2022

The two biggest stories of 2021 in South Korea were a cutthroat presidential nomination and the nationwide outcry over soaring housing prices. Both the ruling and opposition parties had gone through a noisy and murky nomination process. In 2021, housing prices continued to rise, causing citizens’ anxiety and anger to reach their peak, and the president apologized for the failure of the real estate policy. Despite the maladministration, president Moon Jae-in, unlike previous presidents, did not become a lame duck. Meanwhile, the popularity of Hallyu, or the Korean Wave, continued with the success of the movie Minari, K-pop band BTS, and the Netflix drama series Squid Game.
Taiwan in 2021
Authors: Wang T.Y.
Published: February 2022

China heightened its military pressure on Taiwan, but president Tsai In-wen defiantly resisted Beijing’s coercion and overcame domestic criticism. With a cooperative public and international support, Taipei quelled an unexpected COVID-19 outbreak. The bullish economy continues to be fueled by global demand for Taiwan’s technology products as the Taipei–Washington relationship progresses advantageously.
The Philippines in 2021
Authors: Teehankee Julio C.
Published: February 2022

In his last year in office, populist Philippine president Rodrigo Duterte faced the deadly surge of the Delta variant of the COVID-19 pandemic. His government continued to struggle with the health crisis despite implementing one of the most heavy-handed lockdowns in the world. In his final State of the Nation address, he trumpeted his administration’s “war on drugs” and ordered the military to hunt communist insurgents and “shoot them dead.” At the same time, he admitted that he has failed in his “war on corruption,” the second plank in his 2016 campaign platform. His admission foreshadowed the biggest corruption scandal of his administration. The Senate uncovered evidence of financial misuse, particularly for supplies from Pharmally Pharmaceutical, a business formed just months before securing billions of pesos in government supply contracts. The controversy has eroded Duterte’s popularity ratings, but he has retained high enough numbers to leverage political support in the upcoming 2022 presidential election and deflect impending International Criminal Court prosecution for his bloody drug war.
Pakistan in 2021
Authors: Shafqat Sahar
Published: February 2022

Pakistan began the year with an energized opposition that directly challenged the military establishment, but as the year progressed, the opposition alliance fell apart under the strain of internal divisions. The military establishment pushed back against the ruling PTI and regained control of the political system. Religious extremists were emboldened and posed a challenge to both civilian and military centers of power. The economy rebounded from the collapse of 2020, but Pakistan continues to face macro- and micro-economic challenges. The Delta variant took its toll on Pakistanis, but the government was able to make significant progress in its vaccination program by the end of 2021. Pakistan gained considerable geostrategic leverage due to the Taliban takeover in Afghanistan.
Nepal in 2021
Authors: Eck Kristine
Published: February 2022

The COVID-19 pandemic hit Nepal harder in 2021 than in the previous year, resulting in thousands dead, millions of livelihoods lost, food access constricted, educations upended, and social and economic devastation. In the midst of this, political leaders were preoccupied with power politics, leaving the country ill-equipped to manage the COVID-19 crisis. Fragile democratic institutions and norms were undermined by the inability of leaders to prioritize governance. Environmental problems, an economic downturn, and continued human rights violations further exacerbated the country’s woes.
Antimicrobial and antioxidant effects of phlorotannin coating in spoilage prevention of tomato during storage
Authors: Kannikulathel Gopidas Sreekala , Subramani Nagaraj
Published: February 2022

The microbial flora present on vegetables and fruit is commercially significant as they cause spoilage and potential health risks in consumers. Synthetic chemicals used to combat food microbes posed serious health and environmental hazards leading to the search for natural alternatives. In this study, phlorotannins from three Indian brown seaweeds, Sargassum myriocystum, Turbinariaornata, and Padina tetrastromatica were evaluated for antimicrobial, antioxidant, and fruit spoilage prevention potentials. The crude phlorotannin of Padina with the highest content (0.114±0.0005g kg-1) and antioxidant activity (92.65±3.43%) was purified by column chromatography. The Padina water fraction I with the highest antioxidant potential was characterized by Fourier Transform Infra-Red spectroscopy and a 5 % solution was applied as a coating on tomatoes segregated into control chilled (CC), treated chilled (TC), control non-chilled (CNC) and treated non chilled (TNC). Spoilage parameters were studied over twenty days, using a swab and spread plate methods to assess the microbial load on tomatoes. Compared to the control sets, the treated sets exhibited a low number of microbial colonies and retained a fresh look and yellow color. The antibacterial and antioxidant properties of phlorotannin coating as a natural alternative for preservatives, effectively reduced bacterial load, inhibiting the early decay of tomatoes
The main protease of SARS-CoV-2 as therapeutic target to development specific drugs to treat COVID-19
Authors: Silva-Lopez Raquel Elisa
Published: February 2022

The pandemic disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) denominated COVID-19 is an important problem of world public health because do not have specific drugs and vaccines available to control the disease progression and the rapid virusspreading. SARS-CoV-2 genome resemble to other SARS-CoV andMERS-COVcoronaviruses genomes, thus drugs developed for SARS and MERS treatment may be used for COVID-19. The aim of this work is discuss the molecular target of SARS-CoV-2, the main protease, a chymotrypsin-like named as 3CLpro, for a rational devolpment of specific molecules anti-SARS-CoV-2 with broad-spectrum anti-coronavirus activities.This study is a literature mini review using 47 articles obtained from Public Medline and Science directmainly from this year 2020. The coronaviruses infection is mediated by spike protein from viral capsid which bind to ACE2 receptor in the host cells which endocytes the viruses RNA, which is translated to proteins that are cleavead by proteases, mainly the 3CLpro. This enzyme is crucial to SARS-CoV-2 replication and its inhibition can prevent the virus replication. Thus, it is an important coronaviruses target because the amino acid sequence of 3CLpros from SARS, MERS and SARS-CoV-2 have high similarity. In silico studies have been demonstrated that synthetic small molecules, natural products, peptidomimetic inhibitors, and HIV inhibitors had different docking scores with SARS-CoV-23CLpro. However, peptidomimetic inhibitors seems to be better inhibitors to this protease and promise dugs to treat COVID-19 and other diseases caused by coronaviruses
Stability of microencapsulated spray drying carotenoids depending on the composition of the encapsulating matrix
Authors: Tatiana Hernandez-Chamorro
Published: February 2022

Carotenoids are bioactive compounds that can be found in different food matrices. However, these compounds are easily degradable at high temperatures, light and oxygen. Therefore, it is necessary to search for an alternative that avoids such deterioration. Objective: The present study aimed at evaluating the storage stability of microencapsulated palm (Elaeis guineensis) and urucum (Bixa orellana) oil carotenoids by spray drying, depending on the composition of the encapsulation matrix. Methodology: a comparison was made between two types of formulations, a layer composed of isolated soy protein and a double layer composed of isolated soy protein and pectin. The procedure was split into three stages: 1) formulation of stable emulsions; 2) spray drying and 3) characterization of the microcapsules by evaluation of parameters such as encapsulation efficiency, color, humidity and stability of carotenoids over a period of 45 days. Conclusion: the addition of pectin as a double-layer encapsulation material is favorable for all the evaluated parameters except humidity, for which it was not possible to analyze its response during drying