Rotary piezoelectric actuators (RPAs) are widely used in various precise applications. But given the rotary axis offset caused by the single off-center driving force or the discrepancy of multiple piezoelectric elements, most previous works present rotary roundness loss. Besides, there is a contradiction between the motion range of RPA and its response speed. For solving these problems, an RPA based on the spatial screw compliant mechanism (SSCM) is hereby proposed; a theoretical model and an finite element (FE) model are built to verify the actuation principle and guide the structural design; and a prototype is fabricated and tested. The experimental results indicate that the static rotary angle changes from 0 to 4.935 mrad as the voltage changes from 0 to 100 V with a high resolution of 45.53 nrad. The first resonant and −3 dB cutoff frequencies are measured as 1361.5 and 2040.1 Hz, respectively. With the application of the SSCM, the RPA is proven capable of avoiding the rotary roundness loss in theory, and it can balance the milliradian-level rotary range with millisecond-level response speed driving by one lead zirconium titanate (PZT) stack under a small size of Φ32 × 68 mm².

Corn bran is a major agro-industrial byproduct from corn starch processing. The bran is particularly rich in highly substituted feruloylated glucuronoarabinoxylan (FGAX). Yet, due to its recalcitrance to biocatalytic degradation, corn bran FGAX is currently not utilized in biorefinery processes. Here, we report selective enzymatic extraction of both single, and double-stranded high-molecular-weight FGAX molecules from corn bran using a bacterial, glucuronoyl-specific glycoside hydrolase family 30 endo-1,4-β-xylanase (EC 3.2.1.8) from Dickeya chrysanthemi (DcXyn30). The enzymatic extraction using DcXyn30 was optimized with respect to temperature, pH, and time to maximize yields of high-molecular-weight polysaccharides. Examination of the enzymatically extracted FGAX using SEC, HPAEC, LC-MS, and NMR analysis (after acid or alkaline hydrolysis) revealed that both single-stranded and double-stranded FGAX were extracted, since diferulate-linkages were present in the extracted FGAX. Furthermore, the NMR-analysis indicated presence of 1,5-linked arabinan dimers suggesting that some of the xylopyranosyl residues in the extracted FGAX contained arabinofuranosyl-arabinofuranosyl substitutions in addition to a significant amount of classical doubly-arabinose substitutions. Laccase treatment of the extracted FGAX produced strong hydrogels via oxidative, covalent feruloyl-cross-linking. At pH 6.5 the Myceliophthora thermophila derived laccase produced significantly faster cross-linking kinetics than the laccase from Pleurotus ostreatus as measured rheologically. The data reveal novel insight into corn bran FGAX chemistry and provide a new direction for enzyme-assisted upgrading of corn bran for valuable functional hydrogel applications.

A piezoelectric microjet, which can achieve lubrication on demand, is designed to realize the trace redundant lubrication for bearings. The volume of the ejected oil droplet can reach 0.0147 μ L with the velocity of the droplet as 0.91 m/s. A coupling analysis method is proposed to analyze the influences of excitation and oil properties on the dynamic characteristics of droplets. Based on the theory of central oil film thickness, an oil volume prediction model for the trace redundant lubrication of deep groove ball bearings is given. Experiments are carried out, the proposed coupling analysis method is verified by comparing the analysis results with experimental data, and the relative errors are given. The designed microjet is proved to be effective for redundant lubrication by testing its actual lubricating performance. The numbers of voltage pulses, which are required to achieve trace redundant lubrication under different excitations and operating conditions, are given. The validity of the proposed oil volume prediction model is proved by comparing results obtained from experiments and theoretical calculations, and the relative errors are given.