Inspired by the aseismic structure of skyscrapers, Ti6Al4V frames with tubular structure were designed, 3D printed and thermoplastic formed with Zr₃₅Ti₃₀Be_26.75Cu_8.25 bulk metallic glass matrix under ultrasonic vibration, forming sandwich-structured bulk metallic glass composites. The interface characterization between matrix and frame reveals a typical metallurgical bonding. By tuning the geometry of Ti6Al4V frame, the composites manifest an enhanced fracture toughness of 213 MPa m^1/2, 2.3 times higher than that of the monolithic bulk metallic glass. Our findings provide a promising route for the development of metallic composites. Highlights GRAPHICAL ABSTRACT IMPACT STATEMENT A promising route for the design and fabrication of bulk metallic glass composites with tailored mechanical properties was developed by combing ultrasonic vibration-assisted thermoplastic forming and 3D printing.

Bulbus of Fritillaria pallidiflora, the dried bulb of F. pallidiflora, is widely used in Chinese folk medicine due to its powerful biological activities. The aim of this study was to investigate in vitro and in vivo antitumor activity of different fractions and isosteroidal alkaloids from bulbus of F. pallidiflora and clarify its putative mechanism of antitumor activity. Firstly, we assayed in vitro antitumor effects of different fractions from bulbus of F. pallidiflora and found that chloroform extracts and purified total alkaloids of bulbus of F. pallidiflora showed higher cytotoxic activity than other tested extracts. We further isolated four main alkaloids, chuanbeinone, imperialine-β-N-oxide, isoverticine and isoverticine-β-N-oxide, from the total alkaloids of bulbus of F. pallidiflora and found that they display significant cytotoxicity, whereby chuanbeinone showed the highest activity against Lewis lung carcinoma cells. Moreover, we found that chuanbeinone induced S phase arrest and further increased apoptosis of Lewis lung carcinoma cells. The results of Western blotting experiments showed that the expression of the antiapoptotic Bcl-2 was reduced by chuanbeinone treatment, while the proapoptotic protein Bax and caspase-3 were increased. Moreover, we investigated the in vivo antitumor activity of chuanbeinone and characterized its putative antitumor mechanism of action by the TUNEL assay and by histological and immunohistochemical analyses. Our results showed that chuanbeinone exhibited significant antitumor activity in vivo, while notably inhibiting tumor angiogenesis and inducing apoptosis characterized by an increased expression of caspase-3. Our findings show that chuanbeinone exhibits significant antitumor activity in vitro and in vivo, and points to possible therapeutic potential for this compound as well as for its natural source, bulbus of F. pallidiflora.

Under the background of the rapid development of today’s aerospace industry, the bearing characteristics of planetary roller screw drive under high overload conditions are studied. Designing a high-load, high-performance precision planetary roller screw drive is of practical and significant. An axially spaced RV type planetary roller screw with a single nut is designed under aerospace conditions. Under the conditions of the aerospace working load and efficiency, the parameters and structures of the planetary roller screw are completed. Based on this, the bearing characteristics of the planetary roller screw are studied and the equivalent finite element model of the planetary roller screw is analyzed. Those analyses include stress and strain, elastic–plastic properties, transmission efficiency, and dynamic load capacity. The results show that the design of planetary roller screw meets the design requirements for aerospace conditions. And the results can provide a basis for the design and manufacture of planetary roller screws under high loads.

The planetary roller screw mechanism, a novel high-performance electromechanical servo drive component, holds a central position in leading-edge equipment, attracting significant attention within the engineering community. This paper conducts a comprehensive review of current research and recent breakthroughs in the analysis of errors and transmission characteristics associated with the planetary roller screw mechanism. Drawing on the unique attributes of this mechanism, the analysis of errors is undertaken from two distinct angles: motion errors and machining errors. A foundational examination of the bearing characteristics of this mechanism serves as the cornerstone for assessing its transmission properties. The report delves into the impact on transmission performance from the perspectives of both accuracy and efficiency. In this study, each model and related literature are exhaustively described and examined in detail. Furthermore, we critically evaluate the key discoveries emanating from various models and numerical simulations, shedding light on potential future directions in the realm of errors and transmission characteristics of the planetary roller screw mechanism.

Ball screw is a mechanical device widely used in mechanical field. The reverse clearance of ball screw will reduce its precision. In order to eliminate the reverse clearance, it is necessary to apply preload to the ball screw. It is very difficult to measure the preload in real time, and the data are large and time-consuming. By using machine learning method to predict and supervise preload, the changing trend of working condition of ball screw can be evaluated in advance, and the working precision of screw is controlled, which has important engineering significance. In this article, the relationship between the preload and the friction torque is obtained through theoretical derivation and experimental verification. Then, the support vector machine is used as a tool to model the friction torque of ball screw with the parameters of material, lubrication, and revolution, and predict the value and trend of preload to complete the supervision and prediction of the preload of the ball screw. By comparing the experimental results, it is proved that the support vector machine is feasible in predicting and supervising the attenuation of the preload of ball screw.

The eccentric errors of planetary roller screw mechanism (PRSM) affect the contact kinematic characteristics and exacerbate the cumulative wear of thread pairs, which will reduce its transmission accuracy and reliability. Hence, it is significant to investigate the cumulative wear of PRSM with the eccentric errors. In this work, based on the conjugate surface contact condition and Archard wear theory, the sliding speed and cumulative wear depth of PRSM with eccentricity errors are modeled, respectively. The effects of eccentric errors on the sliding velocities and cumulative wear depth of PRSM are investigated. It has been determined that the eccentric errors of the screw and nut do not cause the sliding motion in the nut–roller contact region (NRCR). However, there are noticeable variations in sliding velocity and cumulative wear depth in the screw–roller contact region (SRCR). The eccentric errors of the screw and nut have a combined effect on the sliding velocity and wear between the screw and roller. This investigation and finding can provide a valuable reference for the processing and assembly of PRSM.