Bismuth telluride‐based materials are already being commercially developed for thermoelectric (TE) cooling devices and power generators. However, the relatively low efficiency, which is characterized by a TE figure of merit, zT, is the main obstacle to more widespread application. Significant advances in the TE performance have been made through boundary engineering via embedding nanoinclusions or nanoscale grains. Herein, an effective approach to greatly enhance the TE performance of p‐type BiSbTe material by incorporating carbon microfibers is reported. A high zT of 1.4 at 375 K and high average zT of 1.25 for temperatures in the range of 300 to 500 K is achieved in the BiSbTe/carbon microfiber (BST/CF) composite materials. Their superior TE performance originates from the low thermal conductivity and the relatively high power factor. A TE unicouple device based on the p‐type BST/CF composite material and the commercially available n‐type bismuth telluride‐based material shows a huge cooling temperature drop in the operating temperature range of 299–375 K, and is greatly superior to the unicouple device made of both commercial p‐type and n‐type bismuth telluride‐based material. The materials demonstrate a high average zT and excellent mechanical properties and are strong candidates for practical applications.

Due to the severe mechano-biochemical conditions in the oral cavity, many dental restorations will degrade and eventually fail. For teeth restored with resin composite, the major modes of failure are secondary caries and fracture of the tooth or restoration. While clinical studies can answer some of the more practical questions, such as the rate of failure, fundamental understanding on the failure mechanism can be obtained from laboratory studies using simplified models more effectively. Reviewed in this article are the 4 main types of models used to study the degradation of resin–composite restorations, namely, animal, human in vivo or in situ, in vitro biofilm, and in vitro chemical models. The characteristics, advantages, and disadvantages of these models are discussed and compared. The tooth–restoration interface is widely considered the weakest link in a resin composite restoration. To account for the different types of degradation that can occur (i.e., demineralization, resin hydrolysis, and collagen degradation), enzymes such as esterase and collagenase found in the oral environment are used, in addition to acids, to form biochemical models to test resin–composite restorations in conjunction with mechanical loading. Furthermore, laboratory tests are usually performed in an accelerated manner to save time. It is argued that, for an accelerated multicomponent model to be representative and predictive in terms of both the mode and the speed of degradation, the individual components must be synchronized in their rates of action and be calibrated with clinical data. The process of calibrating the in vitro models against clinical data is briefly described. To achieve representative and predictive in vitro models, more comparative studies of in vivo and in vitro models are required to calibrate the laboratory studies.

In article number 2000757, Xiaolin Wang and co‐workers make a breakthrough in the performance of ultra‐high thermoelectrics in p‐type bulk BiSbTe/Boron nanocomposite materials, which has great potential for wide application in solid‐state refrigeration and power generation.

In this paper, a lightweight high-payload cable-driven serial-parallel manipulator is proposed. The manipulator comprises one 3-degree-of-freedom (3-DOF) shoulder joint and one single-DOF elbow joint. Using a special tension-amplifying principle, which is an ingenious two-stage deceleration method, the proposed manipulator has a higher load/mass ratio than those of conventional manipulators. In this paper, the special tension-amplifying principle is discussed in detail. The shoulder and elbow joints of the proposed manipulator are driven by cables. The design of this cable-driven mechanism and the mobility of the joints are analyzed, and the structural parameters of the joints are optimized to improve the payload capacity. The size of the manipulator is close to that of a human arm because the actuators of the cable-driven mechanism can be rear-mounted. Because the elbow joint is located at the end of the shoulder joint and the driven cables of the elbow joint are coupled with the rotation of the shoulder joint, the manipulator is designed with decoupled cable routing. The overall configuration and cable routing of the manipulator are presented, and then, kinematics, joint stiffness, strength, and workspace of the manipulator are analyzed. Finally, we report on the fabrication of a physical prototype and testing of its joint stiffness, payload capacity, workspace, speed, and repeatability to verify the feasibility of our proposed manipulator.

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Variable stiffness actuators (VSAs) are widely explored as they could improve the safe performance for human-robot interaction and make the system torque controllable based on the internal compliance. This paper presents a novel VSA based on the cam-based relocation mechanism (CRM-VSA), which is utilized to change the locations of pivot and spring of a lever mechanism simultaneously. Consequently, such structure makes the actuator compacted and the stiffness regulation designable which could help engineers to pursue different demands of stiffness regulation. The simultaneous relocations of the pivot and spring also permit a wide range of adjustable stiffness. By introducing linear guide pairs, the internal friction of the relocations of pivot and spring could be greatly reduced, thus enhancing the energy efficiency. To evaluate the performance of the proposed CRM-VSA, the point-to-point control strategy is developed which contributes to a higher tracking accuracy and oscillation attenuation at both the start and end points of the trajectory. Additionally, the performance of torque controllability is also verified through experiments. These excellent capabilities enable the proposed CRM-VSA to be qualified for constructing a robotic arm towards service applications.