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Oxide-dispersion-strengthened CoCrNi alloys were fabricated via in situ oxidation by adding Ti and Y, and non-in-situ oxidation by direct addition of Ti and Y2O3, referring to as Y-ODS and Y2O3-ODS alloys, respectively. Transmission electron microscopy (TEM) and atom probe tomography (APT) characterizations reveal that both alloys consist of an ultrafine-grained face-centered-cubic (fcc) matrix, a high number density of nanoscale Y-Ti-O precipitates and a small number of (Cr0.75Ti0.25)2O3 oxides. However, the nanoscale Y-Ti-O precipitates in the two alloys show distinct phase and microstructure. The Y2O3-ODS alloy contains only incoherent orthorhombic Y2TiO5 nanoprecipitates, but the Y-ODS alloy also contains a high density of fully coherent pyrochlore Y2Ti2O7 nanoprecipitates. The Y-ODS alloy achieves an ultrahigh yield strength of 1660 MPa, which is 320 MPa higher than that of the Y2O3-ODS one, but maintains the same ductility. Quantitative analysis of the strengthening mechanism indicates that such large difference in strength is mainly attributed to the presence of coherent Y2Ti2O7 nanoprecipitates in Y-ODS alloy. This study should provide significant insight into the design of ODS high/medium-entropy alloys via in situ oxidation during mechanical alloying and consolidation.

Compounds displaying aggregation-induced emission behavior may have application in the preparation of smart materials. Here, the authors report a luminogen-containing metal-organic framework for which luminescence intensity changes are observed in response to gas pressure.

Abstract Trivalent lanthanide (Ln3+)‐doped hollow upconversion nanocrystals (UCNCs) usually exhibit unique optical performance that cannot be realized in their solid counterparts, and thus have been receiving tremendous interest from their fundamentals to diverse applications. However, all currently available Ln3+‐doped UCNCs are solid in appearance, the preparation of hollow UCNCs remains nearly untouched hitherto. Herein, a class of UCNCs based on Yb3+/Er3+‐doped tetralithium zirconium octafluoride (Li4ZrF8:Yb/Er) featuring 2D layered crystal lattice is reported, which makes the fabrication of hollow UCNCs with a peasecod‐like shape possible after Ln3+ doping. By employing the first‐principle calculations, the unique peasecod‐like hollow nanoarchitecture primarily associated with the hetero‐valence Yb3+/Er3+ doping into the 2D layered crystal lattice of Li4ZrF8 matrix is revealed. Benefiting from this hollow nanoarchitecture, the resulting Li4ZrF8:Yb/Er UCNCs exhibit an abnormal green upconversion luminescence in terms of the population ratio between two thermally coupled states (2H11/2 and 4S3/2) of Er3+ relative to their solid Li2ZrF6:Yb/Er counterparts, thereby allowing to prepare the first family of hollow Ln3+‐doped UCNCs as supersensitive luminescent nanothermometer with almost the widest temperature sensing range (123–800 K). These findings described here unambiguously pave a new way to fabricate hollow Ln3+‐doped UCNCs for numerous applications.

Increasing CO2 emissions pose serious environmental issues. Here, the authors report the synthesis of a robust metal-organic framework which displays high volumetric uptake of post-combustion CO2 under ambient conditions and can catalyze CO2 fixation into cyclic carbonates.

A Co–30 at.% Cr–5 at.% Ag alloy was fabricated using a combination of mechanical alloying and spark plasma sintering. The microstructure of the alloy consisted of an ultrafine-grained ε-Co solid solution matrix with an average grain size of 167 nm and uniformly dispersed Ag particles with an average size of 72 nm and a minor amount of nanoscale σ-precipitates with size of 23 nm. Such particular microstructure enabled high hardness of 650 HV and compressive strength of up to 2.3 GPa. Pin-on-disk dry sliding wear tests show that the present alloy exhibited superior wear resistance, with wear rate in the order of 10−5 mm3/(N·m) upon sliding against alumina. The wear-induced microstructure extended only ~500 nm from the sliding surface, with elongated Ag particles. The alloy also demonstrated high resistance to corrosion in artificial saliva solution, due to the formation of a protective passive film. Moreover, the addition of Ag also significantly enhanced the antibacterial activity of Co–Cr alloys, with antibacterial rates against E. coli and S. aureus of 90.5% and 72.6%, respectively. The present alloy with a combination of high strength, superior wear- and corrosion-resistance, and excellent antibacterial activity offers a promising candidate for medical implants. Keywords: Co-Cr-Ag alloy, Spark plasma sintering, Sliding wear, Corrosion, Antibacterial

Four lanthanide metal-organic frameworks (Ln-MOFs), namely {[Me2NH2][LnL]·2H2O}n (Ln = Eu 1, Tb 2, Dy 3, Gd 4), have been constructed from a new tetradentate ligand 1-(3,5-dicarboxylatobenzyl)-3,5-pyrazole dicarboxylic acid (H4L). These isostructural Ln-MOFs, crystallizing in the monoclinic P21/c space group, feature a 3D structure with 7.5 Å × 9.8 Å channels along the b axis and the point symbol of {410.614.84} {45.6}2. The framework shows high air and hydrolytic stability, which can keep stable after exposed to humid air for 30 days or immersed in water for seven days. Four MOFs with different lanthanide ions (Eu3+, Tb3+, Dy3+, and Gd3+) ions exhibit red, green, yellow, and blue emissions, respectively. The Tb-MOF emitting bright green luminescence can selectively and rapidly (3+ in aqueous media via a fluorescence quenching effect. The detection shows excellent anti-inference ability toward many other cations and can be easily recognized by naked eyes. In addition, it can also be utilized as a rapid fluorescent sensor to detect acetone solvent as well as acetone vapor. Similar results of sensing experiments were observed from Eu-MOF. The sensing mechanism are further discussed.

Most robots that are actuated by antagonistic pneumatic artificial muscles are controlled by various control algorithms that cannot adequately imitate the actual muscle distribution of human limbs. Other robots in which the distribution of pneumatic artificial muscle is similar to that of human limbs can only analyze the position of the robot using perceptual data instead of rational knowledge. In order to better imitate the movement of a human limb, the article proposes a humanoid lower limb in the form of a parallel mechanism where muscle is unevenly distributed. Next, the kinematic and dynamic movements of bionic hip joint are analyzed, where the joint movement is controlled by an observer-based fuzzy adaptive control algorithm as a whole rather than each individual pneumatic artificial muscle and parameters that are optimized by a neural network. Finally, experimental results are provided to confirm the effectiveness of the proposed method. We also document the role of muscle in trajectory tracking for the piriformis and musculi obturator internus in isobaric processes.