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Abstract Modular reconfigurable robots exhibit prominent advantages in the reconnaissance and exploration tasks within unstructured environments for their characteristics of high adaptability and high robustness. However, due to the limitations in locomotion mechanism and integration requirements, the modular design of miniature robots in the aquatic environment encounters significant challenges. Here, a modular strategy based on the synthetic jet principle is proposed, and a modular reconfigurable robot system is developed. Specialized bottom and side jet actuators are designed with vibration motors as excitation sources, and a motion module is developed incorporating the jet actuators to realize three‐dimensional agile motion. Its linear, rotational, and ascending motion speeds reach 70.7 mm s−1, 3.3 rad s−1, and 28.7 mm s−1, respectively. The module integrates the power supply, communication, and control system with a small size of 48 mm × 38 mm × 38 mm, which ensures a wireless controllable motion. Then, various configurations of the multi‐module robot system are established with corresponding motion schemes, and the experiments with replaceable intermediate modules are further conducted to verify the transportation and image‐capturing functions. This work demonstrates the effectiveness of synthetic jet propulsion for aquatic modular reconfigurable robot systems, and it exhibits profound potential in future underwater applications.

Abstract Miniature resonant piezoelectric robots have the advantages of compact structure, fast response, high speed, and easy control, which have attracted the interest of many scholars in recent years. However, piezoelectric robots usually suffer from the problem of poor adaptability due to the micron‐level amplitude at the feet. Inspired by the fact that earthworms have actuation trajectories all around their bodies to move flexibly under the ground, a miniature piezoelectric robot with circumferentially arranged driving feet to improve adaptability is proposed. Notably, a longitudinal‐vibration‐compound actuation principle with multilegged collaboration is designed to achieve the actuation trajectories around the robot, similar to the earthworms. The structure and operating principle are simulated by the finite element method, and the prototype is fabricated. The robot weighs 22.7 g and has dimensions of 35.5 × 36.5 × 47 mm3. The robot is tethered to an ultrasonic power supply, and the experimental results show that the speed reaches 179.35 mm s−1 under an exciting signal with a frequency of 58.5 kHz and a voltage of 200 Vp‐p. High adaptability is achieved by the proposed robot, it can move on flat, fold, concave, and convex surfaces, and even in an inclined or rotating tube.

Introduction: Dexmedetomidine (DEX), a highly selective α2-adrenergic receptor agonist, is widely used for sedation and anesthesia in patients undergoing hepatectomy. However, the effect of DEX on autophagic flux and liver regeneration remains unclear. Objectives: This study aimed to determine the role of DEX in hepatocyte autophagic flux and liver regeneration after PHx. Methods: In mice, DEX was intraperitoneally injected 5 min before and 6 h after PHx. In vitro, DEX was co-incubated with culture medium for 24 h. Autophagic flux was detected by LC3-II and SQSTM1 expression levels in primary mouse hepatocytes and the proportion of red puncta in AML-12 cells transfected with FUGW-PK-hLC3 plasmid. Liver regeneration was assessed by cyclinD1 expression, Edu incorporation, H&E staining, ki67 immunostaining and liver/body ratios. Bafilomycin A1, si-GSK3β and Flag-tagged GSK3β, α2-ADR antagonist, GSK3β inhibitor, AKT inhibitor were used to identify the role of GSK3β in DEX-mediated autophagic flux and hepatocyte proliferation. Results: Pre- and post-operative DEX treatment promoted liver regeneration after PHx, showing 12 h earlier than in DEX-untreated mice, accompanied by facilitated autophagic flux, which was completely abolished by bafilomycin A1 or α2-ADR antagonist. The suppression of GSK3β activity by SB216763 and si-GSK3β enhanced the effect of DEX on autophagic flux and liver regeneration, which was abolished by AKT inhibitor. Conclusion: Pre- and post-operative administration of DEX facilitates autophagic flux, leading to enhanced liver regeneration after partial hepatectomy through suppression of GSK3β activity in an α2-ADR-dependent manner.

Piezoelectric actuation technology has been widely used in various precise‐oriented fields. Its notable advantages include high resolution, rapid response speed, output force with high density, and immunity to electromagnetic interference. Characteristics of cross‐scale and multiple‐degree‐of‐freedom (multi‐DOF) output motions are of utmost importance in the context of micro‐/nanopositioning technology. For decades, researchers have been working to develop various piezoelectric devices that exploit these important properties. In this review, a comprehensive review of recent research efforts in the field of cross‐scale multi‐DOF piezoelectric drive technology is provided. To commence, it provides an in‐depth exploration of the unique advantages associated with piezoelectric actuation, demonstrating them through comparative analyses with alternative actuation methods. Subsequently, the complexity of piezoelectric cross‐scale motion is introduced, and the multi‐DOF piezoelectric motion is classified in detail. Furthermore, the practical applications of multi‐DOF cross‐scale piezoelectric actuation technology are systematically elucidated, highlighting its versatility and suitability in real‐world environments. Finally, an in‐depth discussion that addresses the challenges encountered in the field is provided, and the prospective directions for further developments in piezoelectric actuation technology are outlined. This scholarly contribution plays an important role in guiding future research and innovative initiatives.

Vibration is a common strategy for aquatic organisms to achieve their life activities, especially at the air–water interface. For the locomotion of small creatures, the organs with plate features are often used on water surfaces, which inspires relevant studies about using thin plates for robot propulsions. However, the influence of the general deformations of thin plates on the generated flow fields has not been considered. Here, a comprehensive investigation is conducted about the flow fields that arose by vibrations of thin plates and the potential as locomotion strategies are explored. It is discovered that as thin plates are subjected to vibration excitations on the water surface, the produced flow fields are mainly determined by the vibration shapes, and the influence rules of plate deformations on the flow fields are identified. The main factors producing asymmetric flow fields are analyzed to realize the morphology control of the flow fields. Then, to determine effective locomotion strategies on the water surface, the flow fields stimulated by integrated vibration exciters are explored, and 2 water surface robots are developed consequentially, which exhibit superior motion performance. This work reveals the basic rules of the vibration-induced-flow mechanism by thin plates and establishes new locomotion strategies for aquatic robots.

Abstract Miniature robots have been widely studied and applied in the fields of search and rescue, reconnaissance, micromanipulation, and even the interior of the human body benefiting from their highlight features of small size, light weight, and agile movement. With the development of new smart materials, many functional actuating elements have been proposed to construct miniature robots. Compared with other actuating elements, piezoelectric actuating elements have the advantages of compact structure, high power density, fast response, high resolution, and no electromagnetic interference, which make them greatly suitable for actuating miniature robots, and capture the attentions and favor of numerous scholars. In this paper, a comprehensive review of recent developments in miniature piezoelectric robots (MPRs) is provided. The MPRs are classified and summarized in detail from three aspects of operating environment, structure of piezoelectric actuating element, and working principle. In addition, new manufacturing methods and piezoelectric materials in MPRs, as well as the application situations, are sorted out and outlined. Finally, the challenges and future trends of MPRs are evaluated and discussed. It is hoped that this review will be of great assistance for determining appropriate designs and guiding future developments of MPRs, and provide a destination board to the researchers interested in MPRs.

Abstract Arachidonic acid (AA), an n‐6 essential fatty acid, is a major component of mammalian cells and can be released by phospholipase A2. Accumulating evidence indicates that AA plays essential biochemical roles, as it is the direct precursor of bioactive lipid metabolites of eicosanoids such as prostaglandins, leukotrienes, and epoxyeicosatrienoic acid obtained from three distinct enzymatic metabolic pathways: the cyclooxygenase pathway, lipoxygenase pathway, and cytochrome P450 pathway. AA metabolism is involved not only in cell differentiation, tissue development, and organ function but also in the progression of diseases, such as hepatic fibrosis, neurodegeneration, obesity, diabetes, and cancers. These eicosanoids are generally considered proinflammatory molecules, as they can trigger oxidative stress and stimulate the immune response. Therefore, interventions in AA metabolic pathways are effective ways to manage inflammatory‐related diseases in the clinic. Currently, inhibitors targeting enzymes related to AA metabolic pathways are an important area of drug discovery. Moreover, many advances have also been made in clinical studies of AA metabolic inhibitors in combination with chemotherapy and immunotherapy. Herein, we review the discovery of AA and focus on AA metabolism in relation to health and diseases. Furthermore, inhibitors targeting AA metabolism are summarized, and potential clinical applications are discussed.

Traditional robotic hands are facing several issues due to limitations in structures, principles and transmissions. Here, the authors develop a rigid robotic hand with 4 piezo fingers and 12 DOFs to implement high adaptability multi-DOF motion manipulation from micro to macro, as well as micro grasping operation.

Ultrasonic-assisted metal droplet deposition (UAMDD) is currently considered a promising technology in droplet-based 3D printing due to its capability to change the wetting and spreading behaviors at the droplet-substrate interface. However, the involved contact dynamics during impacting droplet deposition, particularly the complex physical interaction and metallurgical reaction of induced wetting-spreading-solidification by the external energy, remain unclear to date, which hinders the quantitative prediction and regulation of the microstructures and bonding property of the UAMDD bumps. Here, the wettability of the impacting metal droplet ejected by a piezoelectric micro-jet device (PMJD) on non-wetting and wetting ultrasonic vibration substrates is studied, and the corresponding spreading diameter, contact angle, and bonding strength are also discussed. For the non-wetting substrate, the wettability of the droplet can be significantly increased due to the extrusion of the vibration substrate and the momentum transfer layer at the droplet-substrate interface. And the wettability of the droplet on a wetting substrate is increased at a lower vibration amplitude, which is driven by the momentum transfer layer and the capillary waves at the liquid–vapor interface. Moreover, the effects of the ultrasonic amplitude on the droplet spreading are studied under the resonant frequency of 18.2–18.4 kHz. Compared to deposit droplets on a static substrate, such UAMDD has 31% and 2.1% increments in the spreading diameters for the non-wetting and wetting systems, and the corresponding adhesion tangential forces are increased by 3.85 and 5.59 times.

Existing miniature underwater robots, which use electromagnetic actuators or soft actuators, function in shallow waters. However, in the deep sea, the robots face challenges, such as the miniaturization of the pressure protection unit and the driving method for rapid and agile motions. Herein, a jet‐driven method for a high‐pressure underwater environment is proposed by utilizing the high‐frequency vibration of a piezoelectric vibrator. Thereafter, an antihydropressure miniature robot with a body length of less than 5 cm is designed, which can perform the highly agile actions of floating, sinking, hovering, straight driving, and turning under a water pressure of 20 MPa (equal to the pressure under a water depth of 2000 m). A vertical velocity of 2.95 BH/s and a horizontal velocity of 3.22 BL/s are realized by the prototype, and it achieves faster motions than existing miniature underwater robots. Some potential applications have been realized, including small multicorner pipe exploration by carrying a camera, seaweed epidermal cell sampling in designated areas, and large object transportation by swarming, which proves the high maneuverability and agility of the developed robot. These merits make the robot ideal for multitasking operations in narrow environments with high water pressure, such as multiobstacle seabed.

ABSTRACTMulti-motor configuration of multi-DOF (degree of freedom) optical system is a major source of redundant structure, putting a limitation on the simple and miniaturized design. Thus, a novel two-DOF ultrasonic motor (USM) is proposed to provide a feasible method of application in the lens autofocus of the optical system. The proposed USM operates by one longitudinal mode and two orthogonal bending modes, which is inspired by the bionic motion principle of the earthworms. The frequency degeneration among the three working modes is performed, and the working principle of the USM is verified via the FEM simulation. A prototype of the two-DOF USM is fabricated, and its mechanical output characteristics are tested. The experimental results indicate that the prototype achieves the maximum rotary and linear speeds of 3319.6 rpm and 57.6 mm/s, respectively. Furthermore, we demonstrate the result of a simple focusing experiment using the prototype and obtain a series of clear pictures, which verifies the feasibility of application in the optical focusing system.

The distribution of elite soybean (Glycine max) cultivars is limited due to their highly sensitive to photoperiod, which affects the flowering time and plant architecture. The recent emergence of CRISPR/Cas9 technology has uncovered new opportunities for genetic manipulation of soybean. The major maturity gene E1 of soybean plays a critical role in soybean photoperiod response. Here, we performed CRISPR/Cas9-mediated targeted mutation of E1 gene in soybean cultivar Tianlong1 carrying the dominant E1 to investigate its precise function in photoperiod regulation, especially in plant architecture regulation. Four types of mutations in the E1 coding region were generated. No off-target effects were observed, and homozygous trans-clean mutants without T-DNA were obtained. The photoperiod sensitivity of e1 mutants decreased relative to the wild type plants; however, e1 mutants still responded to photoperiod. Further analysis revealed that the homologs of E1, E1-La, and E1-Lb, were up-regulated in the e1 mutants, indicating a genetic compensation response of E1 and its homologs. The e1 mutants exhibited significant changes in the architecture, including initiation of terminal flowering, formation of determinate stems, and decreased branch numbers. To identify E1-regulated genes related to plant architecture, transcriptome deep sequencing (RNA-seq) was used to compare the gene expression profiles in the stem tip of the wild-type soybean cultivar and the e1 mutants. The expression of shoot identity gene Dt1 was significantly decreased, while Dt2 was significantly upregulated. Also, a set of MADS-box genes was up-regulated in the stem tip of e1 mutants which might contribute to the determinate stem growth habit.

Abstract Amphibious robots can undertake various tasks in terrestrial and aquatic environments for their superior environmental compatibility. However, the existing amphibious robots usually utilize multi‐locomotion systems with transmission mechanisms, leading to complex and bulky structures. Here, a miniature amphibious robot based on vibration‐driven locomotion mechanism is developed. The robot has two unique rigid‐flexible hybrid modules (RFH‐modules), in which a soft foot and a flexible fin are arranged on a rigid leg to conduct vibrations from an eccentric motor to the environment. Then, it can run on ground with the soft foot adopting the friction locomotion mechanism and swim on water with the flexible fin utilizing the vibration‐induced flow mechanism. The robot is untethered with a compact size of 75 × 95 × 21 mm3 and a small weight of 35 g owing to no transmission mechanism or joints. It realizes the maximum speed of 815 mm s–1 on ground and 171 mm s–1 on water. The robot, actuated by the RFH‐modules based on vibration‐driven locomotion mechanism, exhibits the merits of miniature structure and fast movements, indicating its great potential for applications in narrow amphibious environments.

Micromanipulation robots are powerful tools to explore and reform the microscope world, but it is difficult to integrate high precision, long stroke, strong carrying capability, and multi‐degree of freedom (DOF) motions in a single robot. To address this challenge, herein a bioinspired hexapod piezoelectric robot (PER‐hexapod) aiming at high‐performance micromanipulation is presented. Specifically, two piezoelectric elements are integrated in a functional module to provide 3‐DOF precise motions, the collaboration of six functional modules generates the multi‐DOF motions, and the multimode fusion of three gaits facilitates the cross‐scale motion. The robot outputs 6‐DOF motions with resolutions higher than 4 nm or 0.2 μrad, and unlimited traveling ranges of in‐plane motions are accomplished. PER‐hexapod, whose weight is 0.45 kg, can stably drive a carrying load of 10 kg. In addition, PER‐hexapod realizes the accurate positioning with the root‐mean‐square error less than 5 nm. Thus, it has potential applications in the precise positioning in a large range, such as the batch injection of multiple cells and micromachining on large surfaces. Not only PER‐hexapod, but many other robots can be also designed with the same philosophy to construct micromanipulation systems for various requirements.

DNA methylation is an epigenetic modification that plays a vital role in a variety of biological processes, including the regulation of gene expression, cell differentiation, early embryonic development, genomic imprinting, and X chromosome inactivation. PGC7 is a maternal factor that maintains DNA methylation during early embryonic development. One mechanism of action has been identified by analyzing the interactions between PGC7 and UHRF1, H3K9 me2, or TET2/TET3, which reveals how PGC7 regulates DNA methylation in oocytes or fertilized embryos. However, the mechanism by which PGC7 regulates the post-translational modification of methylation-related enzymes remains to be elucidated. This study focused on F9 cells (embryonic cancer cells), which display high levels of PGC7 expression. We found that both knockdown of Pgc7 and inhibition of ERK activity resulted in increased genome-wide DNA methylation levels. Mechanistic experiments confirmed that inhibition of ERK activity led to the accumulation of DNMT1 in the nucleus, ERK phosphorylated DNMT1 at ser717, and DNMT1 Ser717-Ala mutation promoted the nuclear localization of DNMT1. Moreover, knockdown of Pgc7 also caused downregulation of ERK phosphorylation and promoted the accumulation of DNMT1 in the nucleus. In conclusion, we reveal a new mechanism by which PGC7 regulates genome-wide DNA methylation via phosphorylation of DNMT1 at ser717 by ERK. These findings may provide new insights into treatments for DNA methylation-related diseases.

Miniaturization, fast motion, high resolution, high agility, and good adaptability are relatively contradictory characteristics in mobile robot design. It is indeed a challenge to satisfy these performances at the same time. Inspired by the arthropod metamerism in nature, herein, a millirobot composed of three piezoelectric segments is proposed. The millirobot is tethered for power, and the whole size of the millirobot is 58 × 44 × 12 mm; it uses several principles of arthropod locomotion, can carry loads and cross obstacles, and also has the rapidity and agility like a centipede through the coordination of multiple piezoelectric segments. Fast motion with a maximum speed of 516 mm s−1 is realized by operating at resonant mode, and stepping motion with a resolution of 0.44 μm is achieved by the pulsed sinusoidal mode. The widest speed range among published reports of millirobots is achieved (from 4.5e−3 to 9 BL s−1). Its agility surpasses other piezoelectric millirobots; the linear, steering, and rotational motions are performed and switched flexibly. The results show that fast motion, high resolution, wide speed range, high agility, large load capacity, good adaptability, and miniaturization are successfully achieved by the millirobot.

This paper presents a latent-space dynamic neural network (LSDNN) model for the multi-step-ahead prediction and fault detection of a geothermal power plant’s operation. The model was trained to learn the dynamics of the power generation process from multivariate time-series data and the effects of exogenous variables, such as control adjustment and ambient temperature. In the LSDNN model, an encoder–decoder architecture was designed to capture cross-correlation among different measured variables. In addition, a latent space dynamic structure was proposed to propagate the dynamics in the latent space to enable prediction. The prediction power of the LSDNN was utilized for monitoring a geothermal power plant and detecting abnormal events. The model was integrated with principal component analysis (PCA)-based process monitoring techniques to develop a fault-detection procedure. The performance of the proposed LSDNN model and fault detection approach was demonstrated using field data collected from a geothermal power plant.

A rotatable and deployable sleeve mechanism using a longitudinal-bending composite piezoelectric actuator was designed, fabricated, and tested. A two-DOF piezoelectric actuator with single driving foot was designed to work as the driver of the deployable sleeve mechanism: it could push the inner sleeve with linear, rotary, or spiral stretching motions, which was controlled easily by applying different exciting signals. The stretching principles of the proposed deployable sleeve mechanism were illustrated in detail and verified by means of the finite element method. A prototype of the two-DOF piezoelectric actuator was fabricated and the deployable sleeve mechanism was assembled. The mechanical output characteristics of the inner sleeve were tested and discussed. The proposed deployable sleeve mechanism achieved the maximum linear and rotary stretching speeds of 530 mm/s and 240 °/s when the voltage amplitudes and exciting frequencies were 300 Vp-p and 22.35 kHz. The spiral stretching ability of the deployable sleeve mechanism was validated experimentally. The linear and rotary stretching displacement resolutions of the inner sleeve were tested to be about 2 μm and 0.0014°, respectively. The proposed deployable sleeve mechanism obtained quick transient response characteristics with a starting time of 28 ms and a stopping time of 20 ms.

Multi-degree-of-freedom (multi-DOF) piezoelectric motion stage is an important part of modern manufacturing industry. In order to perform high precision outputs in a large travel range, various multi-DOF piezoelectric motion stages have been proposed and applied for decades. This paper is concentrated on reviewing the research on a piezoelectric motion stage. It involves the major components, operating principles of different actuation modes, design schemes, and structures of the multi-DOF piezoelectric motion stages. In this paper, the summary and classification of the actuation modes used in the multi-DOF piezoelectric motion stages are presented, mainly including the resonance actuation mode, inertial actuation mode, clamping and feeding actuation mode, and direct actuation mode; the multi-DOF piezoelectric motion stage is divided into multi-actuator type and single-actuator type according to the number of actuators used in the motion stage, in which the multi-actuator type includes series, parallel, and series-parallel types from the viewpoint of structure mechanism; in addition, the output performances of the stages are compared, and the state of the arts of the stages are discussed and summarized; the further efforts and future research perspectives are highlighted.

A stepper piezoelectric actuator, in which two bending transducers were used to push a runner step-by-step alternatively, was proposed and tested in this paper. Each bending transducer can bend in horizontal ( $X$ ) direction and vertical ( $Y$ ) direction, independently. The bending motion of the transducer in the vertical direction was used to control the contact state between the driving tip and the runner; the linear stepper movement of the runner was accomplished by the horizontal bending motion of the transducer when the driving tips is contacting with the runner. The piezoelectric actuator can realize linear stepper motion by designing the sequences of the bending motions of the two transducers. The operating principle of the stepper driving was illustrated and discussed in detail. A finite-element method was used to simulate the motion trajectories of the driving tips. A prototype was fabricated to verify the operating principle, and the mechanical output characteristics were measured. The runner was pushed linearly step-by-step under four square wave signals with temporal shifts, a maximum no-load speed of $227.3~\mu \text{m}$ /s was achieved, and the maximum output thrust force was tested to be about 14 N. The proposed piezoelectric actuator achieves long stroke, large output force, and precision driving by using two non-resonant bending transducers.

Background/Aims: Self-renewal is one of the most important features of embryonic stem (ES) cells. SC1 is a small molecule modulator that effectively maintains the self-renewal of mouse ES cells in the absence of leukemia inhibitory factor (LIF), serum and feeder cells. However, the mechanism by which SC1 maintains the undifferentiated state of mouse ES cells remains unclear. Methods: In this study, microarray and small RNA deep-sequencing experiments were performed on mouse ES cells treated with or without SC1 to identify the key genes and microRNAs that contributed to self-renewal. Results: SC1 regulates the expressions of pluripotency and differentiation factors, and antagonizes the retinoic acid (RA)-induced differentiation in the presence or absence of LIF. SC1 inhibits the MEK/ERK pathway through Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and pathway reporting experiments. Small RNA deep-sequencing revealed that SC1 significantly modulates the expression of multiple microRNAs with crucial functions in ES cells. The expression of miR124-3p is upregulated in SC1-treated ES cells, which significantly inhibits the MEK/ERK pathway by targeting Grb2, Sos2 and Egr1. Conclusion: SC1 enhances the self-renewal capacity of mouse ES cells by modulating the expression of key regulatory genes and pluripotency-associated microRNAs. SC1 significantly upregulates miR124-3p expression to further inhibit the MEK/ ERK pathway by targeting Grb2, Sos2 and Egr1.

A new driving method for small size legged robots was proposed and tested in this paper, in which the resonant vibrations of four flexible cantilever beams were used to generate the driving forces. The driving principle was elaborated as two sub principles, based on vertical bending vibrations and horizontal bending vibrations, respectively. According to the mode analysis and the harmonic analysis by the finite-element method, a prototype named Resbot was designed and fabricated. Experiments were carried out on two kinds of surfaces. The size of the Resbot was 99 mm × 148 mm × 28 mm, and its maximum speed was measured to be about 17.2 cm/s, which proved the feasibility of the proposed driving method for small legged robots. The relationship between the frequency of the driving force and the velocity of the Resbot demonstrated the availabilities of the two different driving sub-principles. The advantages of the proposed Resbot were that it was not only simple in structure for no intermediate transmission system, but also easy to be miniaturized, since there was no need to design the gaits; furthermore, it used an extremely simple control system.

Machining of hard and brittle materials is usually troublesome due to their high stiffness. In order to improve the processing speed of hard and brittle materials, ultrasonic assisted processing was developed. This paper reports a novel ultrasonic drill method, where longitudinal-bending hybrid ultrasonic vibration is used instead of single longitudinal or bending vibration. The cutting tool in this process is a core drill attached to an ultrasonic transducer, which generates longitudinal and bending vibrations. Thus an elliptical movement with ultrasonic frequency that is vertical to the working surface is formed at the cutting edge. The longitudinal vibration can help the cutting edge impact the workpiece and thus crush it. With the rotation of the cutting tool, the cutting edge scratches a groove on the working surface. While the bending vibration speeds up the movement of the cutting edge toward the workpiece in the working surface so as to amplify the fracture region. Moreover, a radial clearance assisting chip removal is made by the bending vibration. Merits of this machining method, including improved processing speed and avoidance of jamming are verified by experiment.

A four feet driving-type linear piezoelectric actuator, which achieves linear driving motion with step displacement of several microns by the alternating longitudinal motions of three bolt-clamped transducers, is designed and tested. The three transducers are located in I-shape, and the four end tips of the two horizontal transducers are used to drive the runner step-by-step. The horizontal displacements of the driving tips are used to lock the runner, whereas their vertical displacements push the runner linearly. The kinematics of the linear piezoelectric actuator is analyzed and discussed, and the deformations of the transducers are calculated. A prototype is fabricated and tested by an experimental platform. The output displacement has approximately a linear relationship with the amplitude of the voltage, and their ratio is tested to be about 0.01 μm/V. The steady displacement of the driving tip is tested to be about 1.85 μm for one step under voltage of 200 V, and a maximum speed of 141.2 μm/s is achieved under a frequency of 70 Hz.

A sandwich-type multi-degree-of-freedom (MDOF) ultrasonic motor with hybrid excitation is proposed in this paper. The motor adopts pair combination of three resonance modes to drive the sphere rotations around three coordinate axes. When the sphere rotates around any axis, all piezoelectric ceramics of the proposed motor are excited for the vibration of the motor. The final structure parameters of the motor are confirmed by way of finite element method, and the elliptical motion trajectories of the driving areas are verified. At last, the prototype is fabricated and tested. The prototype achieves no-load speeds of 109.8 r/min, 107.9 r/min, and 290.8 r/min in the YOZ, XOZ, and XOY driving modes, respectively. The proposed motor employs only four pieces of lead zirconate titanate ceramics to achieve the MDOF rotations of a spherical rotor.

This paper proposed a new crossbeam ultrasonic motor, which was made of a cross-shaped metal frame and eight pieces of lead zirconate titanate ceramic plates with a size of 10 mm × 3 mm × 1 mm. Two cross-cone-shaped horns were machined at two ends of the crossbeam, and the tips of the horns served as the driving feet. Ellipse trajectories of the two driving feet were generated by superimposing two orthogonal first bending vibrations with the same resonance frequency but a temporal shift of 90°. A Symmetric structure of the proposed ultrasonic motor solved the problem of mode frequencies degeneracy. A new method to excite these two bending vibrations was proposed. Finite-element method simulation was developed to obtain the vibration characteristics of the crossbeam motor. The new excitation method was compared with the traditional one, and it was found that the vibration amplitudes of the driving feet under the new excitation method were about three times that of the traditional one. At last, experiments were accomplished on a fabricated prototype. The two tested first bending resonance frequencies agreed well with each other at ~ 40.5 kHz. Mechanical output performance of the prototype was tested; the maximum speed was ~ 64 r/min, and the maximum output torque was ~ 10.4 mN · m. This paper provides a new idea for an ultrasonic motor with a miniature structure and also a new excitation method for bending vibration.

A new non-resonant-type piezoelectric actuator with unlimited stroke was proposed, in which two transducers operated in hybrid bending modes were used to generate the desired displacements with micrometer scale. Compared with the PZT stack, both positive and negative dc voltages can be applied on the PZT elements to achieve large displacement. The vertical bending movement was used to control the contact state between the foot and the runner, whereas the runner was pushed by the horizontal bending movement. The operating principle of the stepping-wriggle driving was discussed. The motion planning of the bending transducers with eight steps was developed. The duty ratios and the phase difference of the two signals applied on the vertical PZT elements were 1/3 and 180°, respectively, which insured the reliable positioning of the runner. Excitation voltages with different rise times were applied on the PZT elements to discover its effects on the responses of the bending movements by a transient analysis. It was found that the transducer cost about 2 ms to reach the steady state, in spite of the difference of the rise times, but the rise time showed a significant effect on the oscillation amplitude of the bending motion. The motion trajectories of the driving tip were nearly rectangles with horizontal and vertical steady displacements of $\sim 6.10$ and 5.52 $\mu \text{m}$ , respectively. This paper can provide the guidance for the design of non-resonant-type piezoelectric actuator by bending modes.

We report a novel rotary piezoelectric motor using bending transducers in this work. Three transducers are used to drive a disk-shaped rotor together by the elliptical movements of their driving tips; these motions are produced by the hybrid of two first bending vibration modes. The proposed piezoelectric transducer has a simple structure as it only contains an aluminum alloy beam and four pieces of PZT plates. Symmetrical structure is the only necessary condition in the design process as it will ensure the resonance frequencies of the two orthogonal first bending modes are equal. Transducers with first bending resonance frequency of about 53 kHz were fabricated and assembled into a rotary motor. The proposed motor exhibits good performance on speed and torque control. Under a working frequency of 53.2 kHz, the maximum no-load speed and the maximum torque of the prototype are tested to be 53.3 rpm and of 27 mN·m.

Retinoic acid (RA) plays a key role in pluripotent cell differentiation. In F9 embryonic carcinoma cells, RA can induce differentiation towards somatic lineages via the Ras-extracellular signal-regulated kinase (Ras/Erk) pathway, but the mechanism through which it induces the Erk1/2 phosphorylation is unclear. Here, we show that miR-485 is a positive regulator that targets α/β-hydrolase domain-containing protein 2 (Abhd2), which can result in Erk1/2 phosphorylation and triggers differentiation. RA up-regulates miR-485 and concurrently down-regulates Abhd2. We verified that Abhd2 is targeted by miR-485 and they both can influence the phosphorylation of Erk1/2. In summary, RA can mediate cell differentiation by phosphorylating Erk1/2 via miR-485 and Abhd2.

A four-feet walking-type rotary piezoelectric actuator with minute step motion was proposed. The proposed actuator used the rectangular motions of four driving feet to push the rotor step-by-step; this operating principle was different with the previous non-resonant actuators using direct-driving, inertial-driving, and inchworm-type mechanisms. The mechanism of the proposed actuator was discussed in detail. Transient analyses were accomplished by ANSYS software to simulate the motion trajectory of the driving foot and to find the response characteristics. A prototype was manufactured to verify the mechanism and to test the mechanical characteristics. A minimum resolution of 0.095 μrad and a maximum torque of 49 N·mm were achieved by the prototype, and the output speed was varied by changing the driving voltage and working frequency. This work provides a new mechanism for the design of a rotary piezoelectric actuator with minute step motion.

It is important for companies to increase the efficiency of drilling as well as prolong the lifetime of the drilling tool. Since some previous investigations indicated that a superposition of well drilling with an additional vibration increases the drilling efficiency, this paper introduces a novel well drill which is assisted with additional vibrations by means of piezoelectric sandwich bending vibration transducer. The proposed drill uses bending vibrations in two different directions to from an elliptical trajectory movement, which can help the drill to break the surface of hard material more efficiently and clean away the lithic fragments more easily. The proposed well drill with bending vibration transducer is designed to have a resonance frequency of the first bending vibration mode of about 1779 Hz. The motion equation of the particle on the edge of the drill bit is developed and analyzed. The vibration trajectory of the particle on the edge of the drill bit is calculated by using finite element method. A prototype of the proposed drill using bending vibrations is fabricated and tested to verify the aim of drilling efficiency increase. The feed speed of the vibration assisted drilling is tested to be about 0.296 mm/s when the excitation voltage of the transducer is 300 V, while this speed decreases to about 0.195 mm/s when no vibration is added. This comparison shows that the feed speed of the vibration assisted drilling is about 52% higher than that of the normal drilling, which means the proposed drill has a better efficiency and it is important to consider vibration superimposition in well drilling. In addition, the surface of the drill hole gained by the vibration assisted drilling is smoother than that of the normal drilling, which makes the clearance easier.

A novel exciting method for a sandwich type piezoelectric transducer operating in longitudinal-bending hybrid vibration modes is proposed and discussed, in which the piezoelectric elements for the excitations of the longitudinal and bending vibrations share the same axial location, but correspond to different partitions. Whole-piece type piezoelectric plates with three separated partitions are used, in which the center partitions generate the first longitudinal vibration, while the upper and lower partitions produce the second bending vibration. Detailed comparisons between the proposed exciting method and the traditional one were accomplished by finite element method (FEM) calculations, which were further verified by experiments. Compared with the traditional exciting method using independent longitudinal ceramics and bending ceramics, the proposed method achieves higher electromechanical coupling factors and larger vibration amplitudes, especially for the bending vibration mode. This novel exciting method for longitudinal-bending hybrid vibrations has not changed the structural dimensions of the sandwich transducer, but markedly improves the mechanical output ability, which makes it very helpful and meaningful in designing new piezoelectric actuators operated in longitudinal-bending hybrid vibration modes.

A rotary piezoelectric actuator using bolt-clamped type transducer with double driving feet is proposed in this study. The first-order longitudinal and fourth-order bending vibration modes are superimposed in the actuator to produce elliptical movements on the driving tips. Longitudinal PZT and bending PZT are clamped between the exponential shape horns and the flange by bolts. The vibration shape changes of the actuator are presented to give a clear explanation of its working principle. Several structural parameters of the exponential shape horn are selected and adjusted to accomplish the tuning process of the longitudinal and bending resonance frequencies. The input impedance and vibration characteristics are calculated by using FEM method; the gained results verify the feasibility of the proposed actuator. After the fabrication of a prototype, its vibration characteristics are measured by using a scanning laser Doppler vibrometer; the tested results are in good agreement with the FEM calculated results. The mechanical output performance experiments state that the prototype achieves a maximum speed of 129 r/min and a maximum torque of 1.5 Nm.

A modified large thrust ultrasonic linear motor using a T-shape configuration composed of two orthogonal sandwich-type transducers has been proposed in this paper. It is an improved version of a previous T-shape motor. The vertical transducer is used to generate the normal force between the driving foot and slider, while the other push-pull–type horizontal transducer is applied to generate driving force to push the working platform. By superimposing the two longitudinal vibrations, the proposed motor generates an elliptical movement on the driving foot. In order to improve the vibration characteristics and amplify the driving vibration amplitude, the shape of the driving foot and horn have been redesigned and optimized. The finite element method (FEM) is used to adjust the structural parameters to degenerate the two working mode frequencies. The prototype has been fabricated and its mechanical output ability has been measured. The output characteristics of the modified motor, compared with the previous T-shape motor, achieve a relatively high level. The typical no-load speed and maximum output thrust of the prototype are 0.83 m/s and 56 N under an exciting voltage of 150 Vrms.

BACKGROUND: Ultrasonic motors (USM) are based on the concept of driving the rotor by a mechanical vibration excited on the stator via piezoelectric effect. USM exhibit merits such as simple structure, quick response, quiet operation, self-locking when power off, nonelectromagnetic radiation and higher position accuracy. PRINCIPAL FINDINGS: A cylindrical type traveling wave ultrasonic motor using cantilever type composite transducer was proposed in this paper. There are two cantilevers on the outside surface of cylinder, four longitudinal PZT ceramics are set between the cantilevers, and four bending PZT ceramics are set on each outside surface of cantilevers. Two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the cylinder are excited by the composite transducer. In this new design, a single transducer can excite a flexural traveling wave in the cylinder. Thus, elliptical motions are achieved on the teeth. The actuating mechanism of proposed motor was analyzed. The stator was designed with FEM. The two vibration modes of stator were degenerated. Transient analysis was developed to gain the vibration characteristic of stator, and results indicate the motion trajectories of nodes on the teeth are nearly ellipses. CONCLUSIONS: The study results verify the feasibility of the proposed design. The wave excited in the cylinder isn't an ideal traveling wave, and the vibration amplitudes are inconsistent. The distortion of traveling wave is generated by the deformation of bending vibration mode of cylinder, which is caused by the coupling effect between the cylinder and transducer. Analysis results also prove that the objective motions of nodes on the teeth are three-dimensional vibrations. But, the vibration in axial direction is minute compared with the vibrations in circumferential and radial direction. The results of this paper can guide the development of this new type of motor.