Search

AbstractFunctionally graded shape memory alloy (FG-SMA) hold considerable promise for diverse applications in aerospace and micro electro mechanical system (MEMS) fields, owing to their elevated ceramic hardness and distinctive phase transition characteristics. To investigate the mechanical properties and phase transition behaviors of FG-SMA, an FG-SMA specimen was fabricated for the first time using the spark plasma sintering and ball-mill mixing method. Subsequently, microstructure, phase transformation, hardness, compression fracture and shape memory effect testing experiments were carried out. The results revealed a microstructure of the FG-SMA without noticeable pores in the alumina content range of 0.1% to 0.6%. Alumina particles were effectively integrated into the NiTi matrix, enhancing the FG-SMA’s compressive strength. Varied alumina gradients in the FG-SMA cross-section led to distinct phase transitions. The addition of alumina increased the hardness of the NiTi matrix, resulting in higher fracture stress and strain in the FG-SMA. The elastic recovery strain of FG-SMA augmented with increasing alumina content, although the recoverable strain associated with the shape memory effect gradually decreased. This study provides valuable insights for the preparation, optimization, and practical applications of FG-SMAs. At the same time, the research in this article can lay an experimental foundation for the application of FG-SMA in the field of aerospace and MEMS. [ABSTRACT FROM AUTHOR]

Addressing the challenges of limited passability and adaptability encountered by existing pipe robots in navigating through tee and four-way junction pipes, This article designs a pipe robot based on the principle of metamorphism. This robot is designed with a variable number of linkages, constituting the core of its system structure. Through this innovative approach, it achieves movement in diverse types of pipelines by altering its own structural configuration. Kinematic analysis is conducted using both the Denavit-Hartenberg (D-H) method and screw theory, providing expressions for the forward kinematics in terms of the robot's positional and attitudinal states, as well as geometric solutions for the inverse kinematics. Simulations conducted in MATLAB and ADAMS software demonstrate consistent postural changes of the robot, validating its design and capabilities. Prototype experiments in a 500 mm diameter pipeline further confirm the robot's structural design rationality and its ability to navigate through tee and four-way junction pipes by altering its posture. The results indicate that this pipe robot effectively navigates through straight, vertical tee, and horizontal four-way junction pipes, offering a viable solution for efficiently maneuvering through complex pipeline junctions. [ABSTRACT FROM AUTHOR]

With the rapid development of the flexible electronics field, flexible pressure sensors are widely used inwearable devices, medical monitoring and other fields. However, it is still a huge challenge to design a sensor with highsensitivity, low cost and a simple manufacturing process. In this work, we report a flexible strain sensor based on discarded mask straps (MS) with a unique three-dimensional (3D) twist-like network structure. Multi-walled carbon nanotubes (MWCNTs)/carbon nanoparticles (CN)/MS composites were prepared by a simple dip-drying method and encapsulated using a medical Polyurethane (PU) film. It is founded that the fabricated MWCNTs/CN/MS/PU flexible strain sensor (MCMP-FSS) exhibits a high gauge factor (GF) of 13,928 and advanced performance with a large sensing range of 0%–72%. Moreover, good water-repellent harmony and various types of stimuli over 1000 cycles were obtained for the MCMP-FSS. Benefiting from the unique 3D twist-like network structure and the MWCNTs/CN synergistic conductive network, MCMP-FSS also has broad application prospects in the fields of human motion detection, encrypted communication, and natural human-robot interaction. [ABSTRACT FROM AUTHOR]

Advancing catalyst design requires meticulous control of nanocatalyst selectivity at the atomic level. Here, we synthesized two Pd1Ag14 nanoclusters: Pd1Ag14(PPh3)8(SPh(CF3)2)6 and Pd1Ag14(P(Ph-p-OMe)3)7(SPh)6, each with well-defined structures. Notably, in Pd1Ag14(P(Ph-p-OMe)3)7(SPh)6, the detachment of a phosphine ligand from the top silver atom facilitates the exposure of singular active sites. This exposure significantly enhances its selectivity for the electrocatalytic reduction of CO2 to CO, achieving a Faraday efficiency of 83.3% at −1.3 V, markedly surpassing the 28.1% performance at −1.2 V of Pd1Ag14(PPh3)8(SPh(CF3)2)6. This work underscores the impact of atomic-level structural manipulation on enhancing nanocatalyst performance. [ABSTRACT FROM AUTHOR]

The stick-slip type actuator based on the stick-slip driving principle has the characteristics of simple structure, high precision, large travel and no electromagnetic interference. However, the stick-slip driving principle leads to the existence of the displacement backward phenomenon when it is driving in a single direction, which reduces the output performance of the driver. In order to solve the above problem, a stick-slip separated piezoelectric actuator with separable stator and actuator is designed by combining the advantages of lever mechanism and triangle mechanism in this paper, and theoretical calculations and simulations on the flexible hinged amplification mechanism are carried out. The prototype of the stick-slip separable piezoelectric actuator is made, and the output characteristics and speed characteristics of the actuator are experimentally tested to determine the optimum voltage and frequency values for practical operation. [ABSTRACT FROM AUTHOR]

Novel donor–acceptor blends composed of black phosphorus (BP) as an electron donor and C60 as an electron acceptor have been prepared and successfully embedded into a non-optically active poly(methylmethacrylate) (PMMA) matrix producing a BP:C60/PMMA film. In contrast to C60, BP and non-annealed BP:C60 blends, annealed BP:C60 blends show a significantly enhanced optical limiting response due to the thermal-induced intermolecular charge transfer effect between BP and C60. [ABSTRACT FROM AUTHOR]

ABSTRACT pH- and temperature-responsive semi-interpenetrating nanocomposite hydrogels (NC hydrogels) were prepared with surface-functionalized graphene oxide (GO) as the crosslinker, N-isopropylacrylamide (NIPAM) as the monomer, and chitosan (CS) as an additive. The effects of 3-(trimethoxysilyl)propylmethacrylate-modified GO sheets and CS content on various physical properties were investigated. Results show that PNIPAM/CS/GO hydrogels undergo a large volumetric change in response to temperature. Swelling ratios of PNIPAM/CS/GO hydrogels are much larger than those of the conventional organically crosslinked PNIPAM hydrogels. The deswelling test indicates that the deswelling rate was greatly enhanced by incorporating CS into the hydrogel network and using the surface-functionalized GO as the crosslinker. The pH-sensitivity of PNIPAM/CS/GO hydrogels is evident below their volume phase transition temperature. Moreover, the PNIPAM/CS/GO hydrogels have a much better mechanical property compared with traditional hydrogels even in a high water content of 90%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41530. [ABSTRACT FROM AUTHOR]

Advancing catalyst design requires meticulous control of nanocatalyst selectivity at the atomic level. Here, we synthesized two Pd 1 Ag 14 nanoclusters: Pd 1 Ag 14 (PPh 3 ) 8 (SPh(CF 3 ) 2 ) 6 and Pd 1 Ag 14 (P(Ph- p -OMe) 3 ) 7 (SPh) 6 , each with well-defined structures. Notably, in Pd 1 Ag 14 (P(Ph- p -OMe) 3 ) 7 (SPh) 6 , the detachment of a phosphine ligand from the top silver atom facilitates the exposure of singular active sites. This exposure significantly enhances its selectivity for the electrocatalytic reduction of CO 2 to CO, achieving a Faraday efficiency of 83.3% at -1.3 V, markedly surpassing the 28.1% performance at -1.2 V of Pd 1 Ag 14 (PPh 3 ) 8 (SPh(CF 3 ) 2 ) 6 . This work underscores the impact of atomic-level structural manipulation on enhancing nanocatalyst performance.

Novel donor-acceptor blends composed of black phosphorus (BP) as an electron donor and C 60 as an electron acceptor have been prepared and successfully embedded into a non-optically active poly(methylmethacrylate) (PMMA) matrix producing a BP:C 60 /PMMA film. In contrast to C 60 , BP and non-annealed BP:C 60 blends, annealed BP:C 60 blends show a significantly enhanced optical limiting response due to the thermal-induced intermolecular charge transfer effect between BP and C 60 .