Development of a Variable-Configuration Bionic Robotic Fish.

Bionic robotic fish have advantages over traditional underwater propulsion. Most of the existing studies have been conducted with only one type of fish as a bionic object, but a single propulsion mode may not be able to achieve the different needs of underwater operations. In this paper, we designed a pneumatic variable-configuration soft bionic fish and completed the overall structure design. It was built with a cownose ray as the main-configuration bionic object and a Caranx melampygus as the secondary-configuration bionic object. The base structure, actuators, and variable-configuration modules of the robot were made using flexible materials. After completing the design of the structure and control system of the robot, the prototype was manufactured and an underwater test was completed. The tests results indicated that the robot fish could achieve underwater linear propulsion and turning movements in both configurations. The maximum propulsion speed of the main configuration was 38.24 mm/s and the turning angle speed was 5.6°/s, and the maximum propulsion speed of its secondary configuration was 43.05 mm/s and the turning angle speed was 30°/s. The feasibility of the machine fish structure and control scheme were verified.

Design of an Ankle Exoskeleton That Recycles Energy to Assist Propulsion During Human Walking.

OBJECTIVE: Active exoskeletons can handle different walking conditions, but require bulky components (e.g., motors) that need a significant source of power to do so. Purely passive exoskeletons are lightweight and energy-neutral, containing energy-recycling mechanisms that capture energy loss during negative power phases and return it as walking assistance. However, they are usually designed for stereotyped gaits (e.g., walking at fixed speed) and thus show poor adaptivity for variable conditions. This study is aimed to overcome these issues. METHODS: A quasi-passive ankle exoskeleton is designed to integrate the merits of both active and passive exoskeletons, which captures the heel-strike energy loss and recycles it into propulsion. A novel, lightweight, energy-saving clutch and a heel-strike energy-storage mechanism are developed. They are coupled by a series spring that assists user's calf muscles. Six healthy subjects walked with the device on level ground and inclined surfaces to validate its functionality. RESULTS: Level ground studies indicate that the energy-storage mechanism enhances the assistance by increasing the output torque of the exoskeleton. Reductions in metabolic cost (6.4 ± 1.3%, p < 0.05) were observed. During uphill walking, the assistance torque decreased compared with that on level ground, but it still reduced overall metabolic cost compared with baseline walking. During downhill walking, the assistance torque increased, but metabolic cost also slightly increased. CONCLUSION: These results demonstrate the functionality of the prototype on level ground and its limitations on inclined surfaces. SIGNIFICANCE: The proposed device highlights the possibility of widening the potential applications of exoskeletons.

A lariat-based dilatation device for hysteroscopy: an in vitro study.

BACKGROUND: Hysteroscopy is regarded as the golden standard for the therapeutic and diagnostic methods of many uterine diseases. Carbon dioxide, normal saline and pharmaceuticals are generally used to dilate the uterus to obtain enough operating space and clear vision during the surgery. However, these methods often cause various syndromes. METHODS: In this study, we designed a novel mechanical dilator and operating system. The dilator contains a structure with a diameter of 9 mm in its initial status to pass through the narrow cervix after initial cervical dilation by cervical dilator and then its diameter can be expanded up to 60 mm in the working status to achieve a favorable operating space. The operating system is composed of an endoscope and the surgical instrument driving tube. The endoscope was motioned by pre-bent hyperelastic wires and the surgical instrument was driven by a pre-bent driving tube. To obtain the parameters for successful expansion and operation, the relationships between the tension, the diameter of the dilator and the visual and operating space of the operating system were analyzed in detail. On the basis of the obtained parameters, the surgical experiment was performed and the experimental results demonstrated the ability of this dilator to expand and the ability of the operator to operate in small spaces for hysteroscopy. RESULTS: According to the achieved results, the dilator could support the inner wall of the simulated organ to act like a cage, so that the space in the cage was large enough. The operating system can thrust into the intracavity of the simulated uterus through the channel (with a diameter of 6 mm) of the dilator to search for and excise the raised polyp. CONCLUSIONS: It can be concluded that the proposed dilator and operating system can be efficiently applied in organ expansion and operation in hysteroscopy.

Reduced expression of circRNA hsa_circ_0003159 in gastric cancer and its clinical significance.

BACKGROUND: Circular RNAs (circRNAs) play a crucial role in the occurrence of several diseases including cancers. However, little is known about circRNAs' diagnostic values for gastric cancer, one of the worldwide most common diseases of mortality. METHODS: The hsa_circ_0003159 levels in 108 paired gastric cancer tissues and adjacent non-tumorous tissues from surgical patients with gastric cancer were first detected by real-time quantitative reverse transcription-polymerase chain reaction. Then, the relationships between hsa_circ_0003159 expression levels in gastric cancer tissues and the clinicopathological factors of patients with gastric cancer were analyzed. Finally, its diagnostic value was evaluated through the receiver operating characteristic curve. RESULTS: Compared with paired adjacent non-tumorous tissues, hsa_circ_0003159 expression was significantly down-regulated in gastric cancer tissues. What is more, we found that hsa_circ_0003159 expression levels were significantly negatively associated with gender, distal metastasis, and tumor-node-metastasis stage. CONCLUSIONS: All of the results suggest that hsa_circ_0003159 may be a potential cancer marker of patients with gastric cancer.