Accelerated Screening of Ternary Chalcogenides for Potential Photovoltaic Applications.

Chalcogenides, which refer to chalcogen anions, have attracted considerable attention in multiple fields of applications, such as optoelectronics, thermoelectrics, transparent contacts, and thin-film transistors. In comparison to oxide counterparts, chalcogenides have demonstrated higher mobility and p-type dopability, owing to larger orbital overlaps between metal-X covalent chemical bondings and higher-energy valence bands derived by p-orbitals. Despite the potential of chalcogenides, the number of successfully synthesized compounds remains relatively low compared to that of oxides, suggesting the presence of numerous unexplored chalcogenides with fascinating physical characteristics. In this study, we implemented a systematic high-throughput screening process combined with first-principles calculations on ternary chalcogenides using 34 crystal structure prototypes. We generated a computational material database containing over 400,000 compounds by exploiting the ion-substitution approach at different atomic sites with elements in the periodic table. The thermodynamic stabilities of the candidates were validated using the chalcogenides included in the Open Quantum Materials Database. Moreover, we trained a model based on crystal graph convolutional neural networks to predict the thermodynamic stability of novel materials. Furthermore, we theoretically evaluated the electronic structures of the stable candidates using accurate hybrid functionals. A series of in-depth characteristics, including the carrier effective masses, electronic configuration, and photovoltaic conversion efficiency, was also investigated. Our work provides useful guidance for further experimental research in the synthesis and characterization of such chalcogenides as promising candidates, as well as charting the stability and optoelectronic performance of ternary chalcogenides.

Element-Specific Study of Magnetic Anisotropy and Hardening in SmCo5-xCux Thin Films.

This work investigates the effect of copper substitution on the magnetic properties of SmCo5 thin films synthesized by molecular beam epitaxy. A series of thin films with varying concentrations of Cu were grown under otherwise identical conditions to disentangle structural and compositional effects on the magnetic behavior. The combined experimental and theoretical studies show that Cu substitution at the Co3g sites not only stabilizes the formation of the SmCo5 structure but also enhances magnetic anisotropy and coercivity. Density functional theory calculations indicate that Sm(Co4Cu3g)5 possesses a higher single-ion anisotropy as compared to pure SmCo5. In addition, X-ray magnetic circular dichroism reveals that Cu substitution causes an increasing decoupling of the Sm 4f and Co 3d moments. Scanning transmission electron microscopy confirms predominantly SmCo5 phase formation and reveals nanoscale inhomogeneities in the Cu and Co distribution. Our study based on thin film model systems and advanced characterization as well as modeling reveals novel aspects of the complex interplay of intrinsic and extrinsic contributions to magnetic hysteresis in rare-earth-based magnets, i.e., the combination of increased intrinsic anisotropy due to Cu substitution and the extrinsic effect of inhomogeneous elemental distribution of Cu and Co.

Subxiphoid and subcostal arch versus unilateral video-assisted thoracic surgery approaches to thymectomy for myasthenia gravis.

PURPOSE: Thymectomy is an important treatment for myasthenia gravis (MG). We conducted this study to compare the clinical outcomes of the recently introduced subxiphoid and subcostal arch thymectomy (SASAT) approach with those of the standard unilateral video-assisted thoracoscopic surgery (VATS). METHODS: We analyzed, retrospectively, the perioperative, and long-term outcomes of 179 consecutive MG patients (age 18-65 years), who underwent SASAT or unilateral VATS-extended thymectomy between July, 2012 and May, 2019. RESULTS: All demographic and clinical characteristics were comparable in the two groups. The median surgical time, estimated blood loss, thoracotomy conversion rate, total and chest drainage, and complications did not differ significantly between the groups. The visual analog scale (VAS) score was significantly lower in the SASAT group. Complete stable remission (CSR) was achieved in a significantly larger proportion of the SASAT group patients and was significantly higher in women than in men. The Quantitative MG score was significantly lower in the SASAT group. Patients in the MG Foundation of America Clinical Classification groups I and II achieved better remission rates than those in groups III-V. CONCLUSIONS: SASAT is a safe and feasible MG treatment, which may yield better outcomes than unilateral VATS and improve the quality of treatment.

Tailoring Optical Properties in Transparent Highly Conducting Perovskites by Cationic Substitution.

SrMoO3 , SrNbO3 , and SrVO3 are remarkable highly conducting d1 (V, Nb) or d2 (Mo) perovskite metals with an intrinsically high transparency in the visible. A key scientific question is how the optical properties of these materials can be manipulated to make them suitable for applications as transparent electrodes and in plasmonics. Here, it is shown how 3d/4d cationic substitution in perovskites tailors the relevant materials parameters, i.e., optical transition energy and plasma frequency. With the example of the solid-state solution SrV1- x Mox O3 , it is shown that the absorption and reflection edges can be shifted to the edges of the visible light spectrum, resulting in a material that has the potential to outperform indium tin oxide (ITO) due to its extremely low sheet resistance. An optimum for x = 0.5, where a resistivity of 32 µΩ cm (≈12 Ω sq-1 ) is paired with a transmittance above 84% in the whole visible spectrum is found. Quantitative comparison between experiments and electronic structure calculations show that the shift of the plasma frequency is governed by the interplay of d-band filling and electronic correlations. This study advances the knowledge about the peculiar class of highly conducting perovskites toward sustainable transparent conductors and emergent plasmonics.

Machine learning-enabled high-entropy alloy discovery.

High-entropy alloys are solid solutions of multiple principal elements that are capable of reaching composition and property regimes inaccessible for dilute materials. Discovering those with valuable properties, however, too often relies on serendipity, because thermodynamic alloy design rules alone often fail in high-dimensional composition spaces. We propose an active learning strategy to accelerate the design of high-entropy Invar alloys in a practically infinite compositional space based on very sparse data. Our approach works as a closed-loop, integrating machine learning with density-functional theory, thermodynamic calculations, and experiments. After processing and characterizing 17 new alloys out of millions of possible compositions, we identified two high-entropy Invar alloys with extremely low thermal expansion coefficients around 2 × 10-6 per degree kelvin at 300 kelvin. We believe this to be a suitable pathway for the fast and automated discovery of high-entropy alloys with optimal thermal, magnetic, and electrical properties.

Construction of a prognostic model for lung squamous cell carcinoma based on seven N6-methylandenosine-related autophagy genes.

OBJECTIVE: We aimed to construct a novel prognostic model based on N6-methyladenosine (m6A)-related autophagy genes for predicting the prognosis of lung squamous cell carcinoma (LUSC). METHODS: Gene expression profiles and clinical information of Patients with LUSC were downloaded from The Cancer Genome Atlas (TCGA) database. In addition, m6A- and autophagy-related gene profiles were obtained from TCGA and Human Autophagy Database, respectively. Pearson correlation analysis was performed to identify the m6A-related autophagy genes, and univariate Cox regression analysis was conducted to screen for genes associated with prognosis. Based on these genes, LASSO Cox regression analysis was used to construct a prognostic model. The corresponding prognostic score (PS) was calculated, and patients with LUSC were assigned to low- and high-risk groups according to the median PS value. An independent dataset (GSE37745) was used to validate the prognostic ability of the model. CIBERSORT was used to calculate the differences in immune cell infiltration between the high- and low-risk groups. RESULTS: Seven m6A-related autophagy genes were screened to construct a prognostic model: CASP4, CDKN1A, DLC1, ITGB1, PINK1, TP63, and EIF4EBP1. In the training and validation sets, patients in the high-risk group had worse survival times than those in the low-risk group; the areas under the receiver operating characteristic curves were 0.958 and 0.759, respectively. There were differences in m6A levels and immune cell infiltration between the high- and low-risk groups. CONCLUSIONS: Our prognostic model of the seven m6A-related autophagy genes had significant predictive value for LUSC; thus, these genes may serve as autophagy-related therapeutic targets in clinical practice.

Effects of Doping Ni on the Microstructures and Thermoelectric Properties of Co-Excessive NbCoSn Half-Heusler Compounds.

The half-Heusler (HH) compound NbCoSn with 18 valence electrons is a promising thermoelectric (TE) material due to its appropriate electrical properties as well as its suitable thermal and chemical stability. Nowadays, doping/substitution and tailoring of microstructures are common experimental approaches to enhance the TE performance of HH compounds. However, detailed theoretical insights into the effects of doping on the microstructures and TE properties are still missing. In this work, the microstructure of NbCoSn was tailored through precipitating the full-Heusler phases in the matrix by changing the nominal ratio of Co and Ni on the Co sites, focusing on the resulting TE properties. Further, first-principles calculations were employed to understand the relationship between the microstructure and the TE properties from the thermodynamic point of view. Detailed analysis of the electronic structure reveals that the presence of excess Co/Ni contributes to the increasing carrier concentration. Through an increase in the electrical conductivity and a reduction in the thermal conductivity, the TE performance is improved. Therefore, the present work offers a new pathway and insights to enhance the TE properties by modifying the microstructure of HH compounds via tailoring the chemical compositions.

Epitaxy Induced Highly Ordered Sm2Co17-SmCo5 Nanoscale Thin-Film Magnets.

Utilizing the molecular beam epitaxy technique, a nanoscale thin-film magnet of c-axis-oriented Sm2Co17 and SmCo5 phases is stabilized. While typically in the prototype Sm(Co, Fe, Cu, Zr)7.5-8 pinning-type magnets, an ordered nanocomposite is formed by complex thermal treatments, here, a one-step approach to induce controlled phase separation in a binary Sm-Co system is shown. A detailed analysis of the extended X-ray absorption fine structure confirmed the coexistence of Sm2Co17 and SmCo5 phases with 65% Sm2Co17 and 35% SmCo5. The SmCo5 phase is stabilized directly on an Al2O3 substrate up to a thickness of 4 nm followed by a matrix of Sm2Co17 intermixed with SmCo5. This structural transition takes place through coherent atomic layers, as revealed by scanning transmission electron microscopy. Highly crystalline growth of well-aligned Sm2Co17 and SmCo5 phases with coherent interfaces result in strong exchange interaction, leading to enhanced magnetization and magnetic coupling. The arrangement of Sm2Co17 and SmCo5 phases at the nanoscale is reflected in the observed magnetocrystalline anisotropy and coercivity. As next-generation permanent magnets require designing of materials at an atomic level, this work enhances our understanding of self-assembling and functioning of nanophased magnets and contributes to establishing new concepts to engineer the microstructure for beyond state-of-the-art magnets.

Generalized stacking fault energy of carbon-alloyed paramagnetic [Formula: see text]-Fe.

Generalized stacking fault energy (GSFE) is an important parameter for understanding the underlying physics governing the deformation mechanisms in face-centred cubic (fcc) materials. In the present work, we study the long-standing question regarding the influence of C on the GSFE in austenitic steels at paramagnetic state. We calculate the GSFE in both [Formula: see text]-Fe and Fe-C alloys using the exact muffin-tin orbitals method and the Vienna Ab initio Simulation Package. Our results show that the GSFE is increased by the presence of interstitial C, and the universal scaling law is used to verify the accuracy of the obtained stacking fault energies. The C-driven change of the GSFE is discussed considering the magnetic contributions. The effective energy barriers for stacking fault, twinning and slip formation are employed to disclose the C effect on the deformation modes, and we also demonstrate that the magnetic structures as a function of volume explain the effect of paramagnetism on the C-driven changes of the stacking fault energies as compared to the hypothetical non-magnetic case.

[Primary cultured neonate rat sinus node cells: morphology and expression of kir2.1 protein].

OBJECTIVE: To investigate the expression of kir2.1 protein in primary cultured sinus node cells and establish a reliable technique to locate, culture and characterize neonatal rat sinus node cells. METHODS: In paraffin sections, the location and morphology of the neonatal rat sinus node cells were observed by HE staining, silver nitrate staining, myelin staining and phosphotungstic acid-hematoxylin (PTAH) staining. Primary cell culture from the neonatal rat sinus node was conducted to observe the spontaneous contraction frequency, cell morphology and kir2.1 protein expression. RESULTS: Combination of the 3 staining methods allowed accurate localization of the sino-atrial nodal (SAN) tissue, and among the cultured cells in the SAN, at least 3 distinct types of cells with spontaneous contraction were observed. The majority of the contracting cells were spindle cells and their construction and impulse frequency indicated their identity as pacemaker cells, while the triangular and irregular cells resembled the atrial muscle cells. A lower expression level of kir2.1 protein was detected in SAN cells than in the atrial and ventricular myocytes of the neonatal rats. CONCLUSION: Combination of silver nitrate staining, myelin staining and PTAH staining identifies the exact location of the sinus node tissue, and cultured sinus node cells have lower expression of kir2.1 protein than the atrial and ventricular myocytes of neonatal rats.