Core Electron Count as a Versatile and Accurate New Descriptor for Sorting Mechanical Properties of Diverse Transition Metal Compounds.

Transition-metal light-element compounds show superb mechanical, chemical, and thermal properties, and accurate descriptors are important to sorting targeted properties among this vast class of materials. Valence electron concentration (VEC) can track broad trends of mechanical properties, but this widely used descriptor suffers low accuracy with sorted data strongly scattered along trendlines, necessitating an improved sorting strategy. Here, elastic parameters from first-principles calculations are examined for 81 ternary transition-metal nitrides (TMN) in cubic structure and 81 ternary transition-metal diborides (TMB2 ) in hexagonal structure and identify core electron count (CEC) of the solvent atoms as a new descriptor. Combined with VEC, the composite VEC-CEC descriptor exhibits greatly improved ability to sort elastic parameters of distinct TMN and TMB2 compounds. Unregulated property variations under the VEC description are well-captured by CEC, which tends to enhance ductility and reduce strength at fixed VEC and rising CEC. By invoking a full-electron consideration, the VEC-CEC descriptor accounts for the impact on bonding behaviors by both core and valence electrons with much-improved accuracy and versatility in sorting mechanical properties of diverse TM compounds compared to many other commonly used descriptors, opening a fresh path for rational design and optimization of TM compounds with tailored performance benchmarks.

Solving Strength-Toughness Dilemma in Superhard Transition-Metal Diborides via a Distinct Chemically Tuned Solid Solution Approach.

Solid solution strengthening enhances hardness of metals by introducing solute atoms to create local distortions in base crystal lattice, which impedes dislocation motion and plastic deformation, leading to increased strength but reduced ductility and toughness. In sharp contrast, superhard materials comprising covalent bonds exhibit high strength but low toughness via a distinct mechanism dictated by brittle bond deformation, showcasing another prominent scenario of classic strength-toughness tradeoff dilemma. Solving this less explored and understood problem presents a formidable challenge that requires a viable strategy of tuning main load-bearing bonds in these strong but brittle materials to achieve concurrent enhancement of the peak stress and related strain range. Here, we demonstrate a chemically tuned solid solution approach that simultaneously enhances hardness and toughness of superhard transition-metal diboride Ta1-x Zr x B2. This striking phenomenon is achieved by introducing solute atom Zr that has lower electronegativity than solvent atom Ta to reduce the charge depletion on the main load-bearing B-B bonds during indentation, leading to prolonged deformation that gives rise to notably higher strain range and the corresponding peak stress. This finding highlights the crucial role of properly matched contrasting relative electronegativity of solute and solvent atoms in creating concurrent strengthening and toughening and opens a promising avenue for rational design of enhanced mechanical properties in a large class of transition-metal borides. This strategy of concurrent strength-toughness optimization via solute-atom-induced chemical tuning of the main load-bearing bonding charge is expected to work in broader classes of materials, such as nitrides and carbides.

Pt-induced atomic-level tailoring towards paracrystalline high-entropy alloy.

Paracrystalline state achieved in the diamond system guides a direction to explore the missing link between amorphous and crystalline states. However, such a state is still challenging to reach in alloy systems in a controlled manner. Here, based on the vast composition space and the complex atomic interactions in the high-entropy alloys (HEAs), we present an "atomic-level tailoring" strategy to create the paracrystalline HEA. The addition of atomic-level Pt with the large and negative mixing enthalpy induces the local atomic reshuffling around Pt atoms for the well-targeted local amorphization, which separates severe-distorted crystalline Zr-Nb-Hf-Ta-Mo HEA into the high-density crystalline MRO motifs on atomic-level. The paracrystalline HEA exhibits high hardness (16.6 GPa) and high yield strength (8.37 GPa) and deforms by nanoscale shear-banding and nanocrystallization modes. Such an enthalpy-guided strategy in HEAs can provide the atomic-level tailoring ability to purposefully regulate structural characteristics and desirable properties.

Clinicopathological characteristics of peripheral clinical stage IA lung adenocarcinoma with high Ki-67 expression.

BACKGROUND: High Ki-67 expression is associated with poor prognosis in early-stage lung adenocarcinoma (LUAD). However, there are few studies on the associations between clinicopathological features and Ki-67 proliferation index (PI). The study aimed to explore the clinicopathological characteristics of peripheral clinical stage IA LUAD with high Ki-67 expression. METHODS: A case-control study was carried out in China-Japan Friendship Hospital from January 2017 to December 2018. The clinicopathological features of patients were reviewed. Univariate and multivariate analyses were used to analyze the association between clinicopathological characteristics and high Ki-67 expression. RESULTS: Three hundred and seventy-six patients were finally enrolled in the study. Univariate and multivariate analyses showed that males sex (OR =2.23, 95% CI: 1.30-3.83, P=0.004), carcinoembryonic antigen (CEA) positivity (OR =3.25, 95% CI: 1.44-7.33, P=0.005), several imaging features such as notch positivity (OR =2.55, 95% CI: 1.18-5.51, P=0.017), vascular convergence (OR =3.04, 95% CI: 1.03-8.95, P=0.044), and consolidation/tumor ratio (CTR) (OR =1.03, 95% CI: 1.02-1.04, P<0.001) were significantly associated with high Ki-67 expression. The area under curve of receiver operating characteristic (ROC) curve for CTR was 0.813 (95% CI: 0.768-0.858, P<0.001). When cutoff value was 72.5%, the sensitivity and specificity were 80.5% and 76.3%, respectively. CONCLUSIONS: Male sex, CEA positivity, notch positivity, vascular convergence, and CTR were significantly associated with high Ki-67 expression in patients with peripheral clinical stage IA LUAD. These findings could be used to assist clinical decision-making and prognostic evaluation.

Predictive value of radiological features on spread through air space in stage cIA lung adenocarcinoma.

BACKGROUND: Spread through air space (STAS) is a risk factor for disease recurrence in patients with stage IA lung adenocarcinoma (LUAD) who undergo limited resection. Preoperative prediction of STAS could help intraoperative surgical decision-making in small LUAD patients. The aim of the study was to evaluate the predictive value of radiological features on STAS in stage cIA LUAD. METHODS: A case-control study was designed through retrospective analysis of the radiological features of patients who underwent curative surgery for LUAD with a clinical tumor size ≤3 cm. Univariable and multivariable analyses were used to identify the independent risk factors for STAS. The predicted probability of STAS was calculated by a specific formula. Receiver operating characteristic (ROC) curves were used to determine a cut-off value with appropriate specificity while maintaining high sensitivity for STAS positivity. RESULTS: STAS was frequently observed in acinar predominant (P<0.001), micropapillary predominant (P<0.001) and solid predominant (P<0.001) tumors and was significantly associated with larger pT size (P<0.001), presence of micropapillary component (P<0.001), lymphovascular invasion (LVI) (P<0.001), visceral pleura invasion (VPI) (P<0.001), both N1 and N2 lymph node metastasis (P<0.001) and ALK rearrangement (P<0.001). STAS-positivity was significantly associated with the presence of cavitation (P=0.047), lobulation (P=0.009), air bronchogram (P<0.001), and vascular convergence (P=0.016) and was also associated with greater maximum tumor diameter (P<0.001), maximum solid component diameter (P<0.001), maximum tumor area (P<0.001), consolidation/tumor ratio (CTR) (P<0.001), tumor disappearance ratio (TDR) (P<0.001) and computed tomography (CT) value (P<0.001). Multivariable analysis showed that STAS was associated with air bronchogram (P=0.042), maximum tumor diameter (P=0.015), maximum solid component diameter (P=0.022) and CTR (P<0.001). The ROC curve showed that the area under the curve (AUC) was 0.726 in the model for predicting STAS, with a sensitivity and specificity of 95.2% and 36.8%, respectively. CONCLUSIONS: STAS-positive LUAD was associated with air bronchogram, maximum tumor diameter, maximum solid component diameter and CTR. These radiological features could predict STAS with excellent sensitivity but inferior specificity.

Ultralow-Friction and Ultralow-Wear TiN-Ag Solid Solution Coating in Base Oil.

Lubrication plays a pivotal role in reducing energy consumption and machinery wear, profoundly impacting technological and economic development and the environment. A recent study (Erdemir, A., et al. Nature 2016, 536, 67) reported the effective extraction of carbon-based tribofilms from lubricating oil by catalytic activation of the coating material, opening new possibilities for innovative lubrication material research and development. Here, we showcase a solute-atom-strengthened and catalytically functionalized coating design and demonstrate its implementation in a TiN-Ag solid solution film that exhibits concurrent ultralow friction and ultralow wear. Indentation tests and Raman and X-ray photoelectron spectroscopy combined with quantum mechanical simulations uncover the rare superhard nature of the TiN-Ag film along with a solute-Ag-atom-induced self-oxidation mechanism for its outstanding catalytic capacity. These findings identify an outstanding type of mechanically strong and catalytically active coating material with simultaneous superior protective and lubricating functionality, holding great promise for applications ranging from microdevices to large-scale industrial equipment.