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Abstract: We have investigated the electronic and magnetic properties of A-site-ordered perovskite CaFe3Ti4O12 using first-principles calculations. Our calculated results indicate that CaFe3Ti4O12 is mechanically stable and it is an antiferromagnetic insulator. Similar to its isostructural perovskite CaCu3Ti4O12, the primary magnetic coupling mechanism in CaFe3Ti4O12 is ascribed to the Fe–O–Ti–O–Fe superexchange interaction. From this fact we can clearly see that the empty 3d orbitals play an important role to realize the superexchange interaction. Moreover, comparing CaFe3Ti4O12 and CaCu3Ti4O12 in some details, we find that Fe (Cu)–O bond distance is one of the important parameters to determine the antiferromagnetic strength within this superexchange interaction. [Copyright &y& Elsevier]

We have systematically investigated the electronic and magnetic properties of hypothesized A-site-ordered perovskite YMn3Sc4O12 using first-principle calculation based on the density functional theory. Our calculated results predict that YMn3Sc4O12 is both thermodynamically and mechanically stable and its ground state is antiferromagnetic insulator. The Mn3+ is in the high-spin state. More importantly, by comparison to YMn3Al4O12, we point out that the empty Sc 3 d orbital provides the MnOScOMn superexchange interaction, which is similar to its isostructural perovskite CaCu3Ti4O12, and enhances the antiferromagnetic interaction between Mn ions. From these calculations, we can clearly see that the empty 3 d orbital plays an important role to realize superexchange interaction. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011 [ABSTRACT FROM AUTHOR]

We have systematically investigated the electronic and magnetic properties of hypothesized A-site-ordered perovskite YMn3Sc4O12 using first-principle calculation based on the density functional theory. Our calculated results predict that YMn3Sc4O12 is both thermodynamically and mechanically stable and its ground state is antiferromagnetic insulator. The Mn3+ is in the high-spin state. More importantly, by comparison to YMn3Al4O12, we point out that the empty Sc 3 d orbital provides the MnOScOMn superexchange interaction, which is similar to its isostructural perovskite CaCu3Ti4O12, and enhances the antiferromagnetic interaction between Mn ions. From these calculations, we can clearly see that the empty 3 d orbital plays an important role to realize superexchange interaction. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011 [ABSTRACT FROM AUTHOR]

First-principles calculations using the augmented plane wave plus local orbitals method, as implemented in the WIEN2K code, have been carried out to study the A-B intersite charge transfer and the correlated electrical and magnetic properties of the perovskite BiCuFeO, especially as regards the charge transfer. The results indicate that the charge transfer between A-site Cu and B-site Fe is by way of O 2 p orbitals, and during this process orbital hybridization plays an important role. More importantly, the charge transfer is of 3 d + 4 d L→3 d L + 4 d type (here L denotes an oxygen hole or a ligand hole). During this process, the magnetic interaction experiences a transition from Cu-Fe ferrimagnetic coupling to G-type antiferromagnetic coupling within B-site Fe with paramagnetic Cu. As to electrical property, it undergoes a metal to insulator transition. All our calculated results are consistent with the available experimental results. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011 [ABSTRACT FROM AUTHOR]

Abstract: Electronic structure calculations based on density functional theory (DFT) within the generalized gradient approximation (GGA) and GGA+U for manganite cuprate compound LuCu3Mn4O12 have been performed, using the full-potential linearized augmented plane wave method. The calculated results indicate that LuCu3Mn4O12 is ferrimagnetic and half-metallic in both GGA and GGA+U calculations. The minority-spin band gap is 0.7eV within GGA, which is larger than that of LaCu3Mn4O12 (0.3eV), indicating its better half-metallicity. Further, the minority-spin gap enlarges from 0.7 to 2.8eV with U taken into account, and simultaneously the Fermi level being shifted to the middle of the gap, making the half-metallic energy gap to be 1.21eV. These results demonstrate that electronic correlation effect enhances the stability of half-metallic property. These facts make this system interesting candidates for applications in spintronic devices. [ABSTRACT FROM AUTHOR]

Abstract: The magnetic and electronic properties of Ba2MnMoO6 are investigated by using the full-potential linearized augmented plane-wave method, with both generalized gradient approximations (GGA) and GGA+ U approaches. The calculated results indicate that parameter U plays a vital role in the electronic structure characterization. The ground state is found to be antiferromagnetic and insulating. In terms of the Heisenberg model, the nearest-neighbor and the next-nearest-neighbor magnetic interaction parameters are determined to be J 1 =−1.17meV and J 2 =−0.87meV. The valence states of Mn and Mo are suggested to be divalent and hexavalent respectively, in agreement with the experimental data. [Copyright &y& Elsevier]

Abstract: The electronic and magnetic properties of the recently synthesized A-site-ordered perovskites A′Cu3Sn4O12 with A′=Ca2+, Sr2+, and Pb2+ were investigated by use of the density functional theory. The results indicate that the ground states of them are all ferromagnetic insulator and the magnetic properties are determined primarily by the direct ferromagnetic interaction between A-site Cu2+ ions, which is consistent with the available experimental results. By replacing bivalent A′ ion by trivalent La ion, we found that the electron is injected into A-site Cu and LaCu3Sn4O12 is predicted to be ferromagnetic half-metallic. [Copyright &y& Elsevier]

Within RCu3Mn4O12 (R=Rare earth), besides the expected ferrimagnetic order of Mn and Cu ions below TC1, R magnetic moments also play an important role at lower temperatures TC2, leading to their peculiar magnetic behavior. By first-principles calculation, we found that along the series from La to Lu, TC1 monotonically increased due to the ionic radius (IR) induced chemical pressure, as experimentally observed, while TC2 is closely related to the atomic radius of R. Additionally, the magnetic anisotropy energy (ΔEani) along the series is found to be correlated with the total magnetic moment of R ion. [ABSTRACT FROM AUTHOR]

American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) being most widely applied in clinical practice, there is an overlap in US imaging manifestations between benign and malignant thyroid nodules. To analyze the imaging and histological characteristics of pathological benign thyroid nodules categorized as American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) 4 or 5, and to explore the correlation between the suspicious sonographic signs resulting in the misdiagnoses and the histopathological features. Overall, 227 benign thyroid nodules (215 patients) in ACR TI-RADS 4 or 5 sampled through surgical excision were analyzed between December 2020 and August 2022. We retrospectively reread the ultrasound (US) images of the pathological discordant cases, after which we performed a systematic analysis focusing on the histopathological characteristics of thyroid lesions and recorded the findings. Qualitative US features and pathological significance of the thyroid nodules were analyzed using the chi-square and Fisher's exact tests. The pathological type of 227 thyroid nodules (n = 103 in ACR TI-RADS 4 and n = 124 in ACR TI-RADS 5) was nodular goiter together with other histopathological features, namely, fibrosis (n = 103, 45.4 %), calcification (n = 70, 30.8 %), adenomatous hyperplasia (n = 31, 13.7 %), follicular epithelial hyperplasia (n = 23, 10.1 %), Hashimoto's thyroiditis (n = 18, 7.9 %), and cystic degeneration (n = 16, 7.1 %). Fibrosis was the most common histopathological feature in both ACR TI-RADS 4 (n = 42, 40.8 %) and 5 (n = 61, 49.2 %) categories of benign thyroid nodules. Thyroid nodules with fibrosis demonstrated sonographic features of "taller than wide" (p < 0.05), while lesions with follicular epithelial hyperplasia were likely to be detected with irregular and/or lobulated margins and very hypoechoic on US (p < 0.05 for both). Benign thyroid nodules with histopathological findings such as fibrosis are associated with suspicious US features, which may give inappropriately higher TIRADS stratification. [ABSTRACT FROM AUTHOR]

A Mg−15 wt%Gd binary alloy was prepared by hot-extrusion and then creep-aged at 200 °C under a constant stress of 200 MPa in this work. Compared with the traditional aging, creep aging clearly accelerated the age-hardening response, as the aging time for the peak yield strength was shorten from 72h to ∼16h. In the peak-creep-aged sample, a novel precipitation structure, named as β′ H herein, was observed as the dominant precipitate. Interestingly, these dense β′ H precipitates preferred to distributing along a certain direction which generally deviated from the extrusion direction (ED) by 54–67°. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) characterization revealed that this novel β′ H precipitate is composed of distorted Gd-rich hexagonal units, with the chemical formula of Mg 7 Gd 2 and having a monoclinic structure, a = 0.671 nm, b = 1.727 nm, c = 0.521 nm and β = 100.7°. Density functional theory (DFT) calculations suggest that the applied stress during creep aging could provide an effective tensile stress for the motion of the surrounding Mg atoms when forming the β′ H structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • A covalent triazine framework coating strategy is utilized to prevent Zn dendrite and side reactions. • The porous framework structure and zincophilic triazine ring facilitate uniform Zn deposition. • Long life and low polarization of 36 mV for symmetric batteries have been achieved. The development of aqueous zinc-ion batteries is greatly hindered by the intrinsic defects of Zn metal anodes, such as uncontrollable dendrite growth and complicated side reactions. Herein, a covalent triazine framework (CTF), with abundant zinc ion transfer channels and strong chemical stability, is fabricated as a coating layer of zinc anodes to address these problems. The CTF layer not only regulates uniform Zn2+ transport path but also effectively separates zinc anodes from bulk electrolytes, thereby preventing the occurrence of side reactions. Moreover, the triazine ring can serve as zincophilic sites to enhance Zn deposition kinetics. Thus, the CTF-protected Zn anode enables a Zn//Zn symmetric cell to achieve a long cycle lifespan of over 7000 h, about 40 times larger than that of bare Zn anodes. This symmetric cell also has a low and stable voltage polarization of 36 mV even after 3000 h. Meanwhile, the full cell coupled with calcium-doped V 2 O 5 exhibits capacity retention of 66.7 % after 300 cycles at a current density of 1 A g−1, while the cell with bare Zn anode could only retain 24.3 % of capacity under the same condition. This work provides a promising method to address the anode problems in metal-ion batteries. [ABSTRACT FROM AUTHOR]

Abnormal creep stress exponents (n) are frequently reported for heat-resistant magnesium alloys, but hitherto without in-depth elucidation or rationalization from the underlying creep mechanisms. In this work, tensile creep behavior of a high-pressure die casting Mg−3.76Al−3.52RE−0.23Mn (wt.%) alloy at 200 °C were studied, adopting small applied stress intervals of 1–2.5 MPa. The result indicates a roller-coaster n -value evolution of 5 → 23 → 38 → 8 → 45 → 76, as the applied stress increases from 80 MPa to 100 MPa. Microstructural analysis using transmission electron microscopy suggests that basal slip of dislocations is dominant at lower stresses while dislocation climb at higher stresses and, simultaneously, twinning becomes more prominent and other sub-microstructures such as dislocation bands gradually occur as the applied stress increases such as to 87 MPa. By simultaneously introducing a threshold stress and an internal stress, the abnormal n -values are rationalized to 3.0 at relatively lower stresses and gradually to 7.7 at higher stresses, corresponding basal slip of dislocations to dislocation climb. Therefore, we suggest that alloy design aimed to improve creep resistance of magnesium alloys should pay more attention to impeding dynamic twinning during creep. [ABSTRACT FROM AUTHOR]

High-entropy perovskite oxides (HEPOs) suffer from inferior stability in high-power battery-supercapacitor hybrid (BSH) devices. Therefore, revealing their energy storage mechanism is extremely important for optimizing appliance stability. Herein, La 0.7 Bi 0.3 Mn 0.4 Fe 0.3 Cu 0.3 O 3 nano-HEPO exhibits the dual-ion energy storage mechanism in aqueous alkaline BSH devices. The rapid deintercalation of oxygen anions from the (sub)surface facilitates the intercalation of hydrogen cations into the bulk during charging; however, the deintercalation of hydrogen cations upon the discharge process is hindered because of the surface filling with oxygen vacancies, resulting in an irreversible phase transition and volumetric expansion. Meanwhile, the evolution of surface oxygen species leads to the weak binding between the surface metal-oxygen polyhedron and the bulk, causing severe capacity deterioration due to the active cation leaching and surface inactive La(OH) 3 aggregation. Finally, optimal strategies are presented based on the dual-ion intercalation chemistry of HEPOs for application in high-performance BSH devices with long service life. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Controllable synthesis of NVO materials with diverse structures is achieved. • The NVO nanodots are demonstrated to contain abundant oxygen vacancies. • The vacancy-rich NVO cathode exhibits outstanding reaction kinetics and cycling stability. Vanadium-based materials are one of the most promising cathodes for aqueous zinc ion batteries owing to their adjustable layered structure and high specific capacity. However, the sluggish Zn2+ diffusion kinetics and inferior structural stability still hinder their further development. Here, selective control of the structure of ammonium vanadate (NVO) materials is successfully achieved by a simple hydrothermal method, and the relationship between structure and performance is clarified. It was found that the amount of citric acid in the precursor solution is a vital factor for this morphology evolution. Density functional theory calculations show that the oxygen vacancies could modulate the electron structure of NVO and effectively weaken the electrostatic interaction between Zn2+ and the NVO lattice. Benefitting from the isotropic structure with abundant oxygen vacancies, the amorphous NVO nanodots exhibit superior reaction kinetics. The specific energy of 148.5 Wh kg−1 was achieved at a power density of 3300 W kg−1, along with a high capacity retention of 81% even after 5000 cycles at 5 A g−1. This work not only provides a new strategy for the controllable synthesis of vanadium-based materials but also reveals the great application potential of amorphous materials in metal-ion batteries. [ABSTRACT FROM AUTHOR]

An ultrathin wall Mg-8Zn-8Al (wt%) alloy was manufactured by high-pressure die casting (HPDC), and exhibits standout strength of ∼ 248 MPa with an acceptable elongation of ∼2.3%. Interestingly, this alloy contains relatively coarse α-Mg grains (∼ 5.6 µm) and ultra-fine β-Mg grains (∼ 0.67 µm), and many nano-sized icosahedral quasicrystal phase (I-phase) particles in eutectic regions. Atomic-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) observations reveal possible amorphous regions around I-phase particles, C-containing phase and/or MgO aggregations, and Zn-rich clusters and pyramidal precipitates. Both ultra-fine grains along with the skeleton consisted of nano-sized I-phase particles and solutes including Zn-rich clusters in Mg matrix contribute the ultra-high strength. On the other hand, this work indicates that interaction of alloy melt with CO 2 is avoidless during ultra-thin wall HPDC and pyramidal precipitation is possible at least in Zn-containing magnesium alloys. • An ultrathin wall Mg-Zn-Al alloy was manufactured to have ultra-high strength. • It contains coarse α-Mg grains (∼ 5.6 µm) and ultra-fine β-Mg grains (∼ 0.67 µm). • Intermetallic skeleton is consisted of nanosized I-particles and amorphous areas. • Novel C-containing phase and pyramidal precipitate are firstly reported in Mg. [ABSTRACT FROM AUTHOR]

Effects of various Sm additions on microstructures and mechanical properties of a hot-extruded Mg–14Gd−0.5Zr alloy were studied in this work. The results indicate that Sm addition firstly clearly improves the strength and then decrease as the Sm content increases at both room temperature and high temperatures. The highest yield strength was obtained to be ∼495 MPa and ∼512 MPa under tension and compression, respectively, at room temperature with the Sm concentration of 1 wt% while those were to be 384 MPa and 248 MPa at 250 °C and 300 °C, respectively, with the Sm content of 0.5 wt%. Electron backscatter diffraction mappings reveal that Sm addition significantly promotes dynamic recrystallization, resulted in much more fine recrystallized grains and lower texture intensity. Furthermore, transmission electron microscopy observations show that Sm addition increases dynamic precipitates particularly in non-recrystallized regions, leading to relatively less aging precipitates during artificial peak-aging. Finally, discussion based on grain boundary strengthening and dispersion strengthening suggests that Sm addition improving the yield strength of the extruded Mg–14Gd−0.5Zr alloy is mainly attributed to more grain boundaries and dynamic precipitates at room temperature and high temperatures, respectively. [ABSTRACT FROM AUTHOR]

Abstract: We report a synthesis of two types of CeO2 nano-rods via the facile and efficient hydrothermal process free from any surfactant and template. The synthesized nano-rods are chemically identified as CeO2 with the standard fluorite structure but their morphologies are different. The nano-rods prepared with cerium nitrate hexahydrate and sodium phosphate are thicker and shorter with diameter of ∼30nm and length of ∼100nm, and those prepared with cerium acetate hydrate and dibasic sodium phosphate are thinner and longer with ∼10nm in diameter and ∼400nm in length. Microstructural analyses reveal that the two species of nano-rods have low-energy {111} surfaces and grow along the 〈112〉 direction. As a consequence of their morphologies, the two types of synthesized nano-rods exhibit excellent UV-absorption ability in comparison to the irregular CeO2 nanoparticles. [Copyright &y& Elsevier]

• MoSe 2 monolayer can tolerate a large range of elastic strain. • Strain engineering is an effective approach to modulate the band structure of MoSe 2 monolayer. • The strained MoSe 2 monolayer still maintains the semiconductor property. First-principles calculations were carried out to study the influence of strain on the electronic structure of MoSe 2 monolayer. Both uniaxial and biaxial strain were taken into consideration, and our calculations reveal that MoSe 2 monolayer can tolerate a large range of elastic strain. More importantly, the electronic structure of MoSe 2 monolayer can be significantly tuned by strain, which is attributed to the redistribution of Mo 4d and Se 4p orbitals. However, the strained MoSe 2 monolayer still maintains the semiconductor properties, although its bandgap undergoes a transition from direct to indirect over a certain amount of strain. [ABSTRACT FROM AUTHOR]

We have systematically investigated the electronic and magnetic properties of hypothesized A-site-ordered perovskite YMn₃Sc₄O₁₂ using first-principle calculation based on the density functional theory. Our calculated results predict that YMn₃Sc₄O₁₂ is both thermodynamically and mechanically stable and its ground state is antiferromagnetic insulator. The Mn(3+) is in the high-spin state. More importantly, by comparison to YMn₃Sc₄O₁₂, we point out that the empty Sc 3d orbital provides the Mn--O--Sc--O--Mn superexchange interaction, which is similar to its isostructural perovskite CaCu₃Ti₄O₁₂, and enhances the antiferromagnetic interaction between Mn ions. From these calculations, we can clearly see that the empty 3d orbital plays an important role to realize superexchange interaction., (2011 Wiley Periodicals, Inc.)