Fast-Swimming Soft Robotic Fish Actuated by Bionic Muscle.

Soft underwater swimming robots actuated by smart materials have unique advantages in exploring the ocean, such as low noise, high flexibility, and friendly environment interaction ability. However, most of them typically exhibit limited swimming speed and flexibility due to the inherent characteristics of soft actuation materials. The actuation method and structural design of soft robots are key elements to improve their motion performance. Inspired by the muscle actuation and swimming mechanism of natural fish, a fast-swimming soft robotic fish actuated by a bionic muscle actuator made of dielectric elastomer is presented. The results show that by controlling the two independent actuating units of a biomimetic actuator, the robotic fish can not only achieve continuous C-shaped body motion similar to natural fish but also have a large bending angle (maximum unidirectional angle is about 40°) and thrust force (peak thrust is about 14 mN). In addition, the coupling relationship between the swimming speed and actuating parameters of the robotic fish is established through experiments and theoretical analysis. By optimizing the control strategy, the robotic fish can demonstrate a fast swimming speed of 76 mm/s (0.76 body length/s), which is much faster than most of the reported soft robotic fish driven by nonbiological soft materials that swim in body and/or caudal fin propulsion mode. What's more, by applying programmed voltage excitation to the actuating units of the bionic muscle, the robotic fish can be steered along specific trajectories, such as continuous turning motions and an S-shaped routine. This study is beneficial for promoting the design and development of high-performance soft underwater robots, and the adopted biomimetic mechanisms, as well as actuating methods, can be extended to other various flexible devices and soft robots.

Steering Muscle-Based Bio-Syncretic Robot Through Bionic Optimized Biped Mechanical Design.

Bio-syncretic robots consisting of artificial structures and living muscle cells have attracted much attention owing to their potential advantages, such as high drive efficiency, miniaturization, and compatibility. Motion controllability, as an important factor related to the main performance of bio-syncretic robots, has been explored in numerous studies. However, most of the existing bio-syncretic robots still face challenges related to the further development of steerable kinematic dexterity. In this study, a bionic optimized biped fully soft bio-syncretic robot actuated by two muscle tissues and steered with a direction-controllable electric field generated by external circularly distributed multiple electrodes has been developed. The developed bio-syncretic robot could realize wirelessly steerable motion and effective transportation of microparticle cargo on artificial polystyrene and biological pork tripe surfaces. This study may provide an effective strategy for the development of bio-syncretic robots and other related studies, such as nonliving soft robot design and muscle tissue engineering.

[Relationship Between Maternal Negative Emotions and Feeding Patterns of Infants Aged 0-6 Months in Remote Rural Areas of Sichuan Province].

Objective To investigate the status of exclusive breastfeeding and bottle feeding in remote rural areas of Sichuan province and explore the relationship between negative emotions of mothers and feeding patterns of infants.Methods Multistage cluster sampling was employed to select the infants aged 0-6 months and their mothers in remote rural areas of Sichuan province.A self-designed questionnaire was used to collect the demographic characteristics of mothers and infants and the basic family information.The Chinese version of Depression Anxiety Stress scale was used to evaluate mothers' negative emotions,and the Breastfeeding Self-efficacy scale to assess the confidence level of mothers' behavior of adhering to exclusive breastfeeding.Results Totally 723 pairs of infants and their mothers were included.The exclusive breastfeeding and bottle feeding rates were 34.16% (247/723) and 57.54% (416/723),respectively.Mothers with depression tendency were less likely to adopt exclusive breastfeeding (OR=0.532,95%CI=0.291-0.974,P=0.041) and more likely to adopt bottle feeding (OR=1.877,95%CI=1.054-3.344,P=0.033).Further subgroup analysis of breastfeeding self-efficacy showed that in the group of low self-efficacy,the mothers with depression tendency were less likely to adopt exclusive breastfeeding (OR=0.461,95%CI=0.236-0.902,P=0.024) and more likely to adopt bottle feeding (OR=1.968,95%CI=1.047-3.701,P=0.036) than the mothers without depression tendency.In the group of high self-efficacy,mothers' depression,anxiety,and stress tendency had no significant correlation with infant feeding patterns (all P>0.05).Conclusions The mothers in the remote rural areas of Sichuan province are more likely to employ bottle feeding than exclusive breastfeeding.The mothers with stronger depression tendency demonstrate lower possibility of exclusive breastfeeding and higher possibility of bottle feeding.Breastfeeding self-efficacy may affect the association between maternal depression and infant feeding patterns.

Uncover rock-climbing fish's secret of balancing tight adhesion and fast sliding for bioinspired robots.

The underlying principle of the unique dynamic adaptive adhesion capability of a rock-climbing fish (Beaufortia kweichowensis) that can resist a pull-off force of 1000 times its weight while achieving simultaneous fast sliding (7.83 body lengths per second (BL/S)) remains a mystery in the literature. This adhesion-sliding ability has long been sought for underwater robots. However, strong surface adhesion and fast sliding appear to contradict each other due to the need for high surface contact stress. The skillfully balanced mechanism of the tight surface adhesion and fast sliding of the rock-climbing fish is disclosed in this work. The Stefan force (0.1 mN/mm2) generated by micro-setae on pectoral fins and ventral fins leads to a 70 N/m2 adhesion force by conforming the overall body of the fish to a surface to form a sealing chamber. The pull-off force is neutralized simultaneously due to the negative pressure caused by the volumetric change of the chamber. The rock-climbing fish's micro-setae hydrodynamic interaction and sealing suction cup work cohesively to contribute to low friction and high pull-off-force resistance and can therefore slide rapidly while clinging to the surface. Inspired by this unique mechanism, an underwater robot is developed with incorporated structures that mimic the functionality of the rock-climbing fish via a micro-setae array attached to a soft self-adaptive chamber, a setup which demonstrates superiority over conventional structures in terms of balancing tight underwater adhesion and fast sliding.

[Current Situation and Influencing Factors of Delay in Seeking Medical Treatment Among Residents in Rural Areas of Sichuan Province].

Objective To understand the current situation and explore the influencing factors of delay in seeking medical treatment for common symptoms of residents in the rural areas of Sichuan province. Methods In July 2019,multi-stage random sampling was carried out in Zigong city,Sichuan province,and the data were collected by face-to-face questionnaire interview.The residents who had lived at hometown for more than half a year in the past year and had seen a doctor in the most recent month were surveyed.Logistic regression was adopted to predict the influencing factors of delay in seeking medical treatment. Results A total of 342 subjects were enrolled,and the incidence of delay in seeking medical treatment was 13.45%(46/342).Compared with the young and middle-aged(<65 years)people,the elderly(≥65 years)people were more likely to have delay in seeking medical treatment (OR=2.187,95%CI=1.074-4.457,P=0.031).The rural residents who gave higher score of the overall quality of township health centers were less likely to have delay in seeking medical treatment (OR=0.854,95%CI=0.735-0.992,P=0.039). Conclusions The occurrence of delay in seeking medical treatment for common symptoms of rural residents in Sichuan province is low.Age and the overall quality evaluation of township health centers affect the occurrence of delay in medical treatment among the rural residents in Sichuan province.Efforts should be made to improve the awareness of disease prevention among the elderly in rural areas.The investment in health resources in township health centers should be increased to strengthen the introduction and training of talents.These measures can improve the health services in township health centers,guide residents to make timely use of health resources,and reduce the occurrence of delay in seeking medical treatment.

Effect of the Laying Order of Core Layer Materials on the Sound-Insulation Performance of High-Speed Train Carbody.

The design of sound-insulation schemes requires the development of new materials and structures while also paying attention to their laying order. If the sound-insulation performance of the whole structure can be improved by simply changing the laying order of materials or structures, it will bring great advantages to the implementation of the scheme and cost control. This paper studies this problem. First, taking a simple sandwich composite plate as an example, a sound-insulation prediction model for composite structures was established. The influence of different material laying schemes on the overall sound-insulation characteristics was calculated and analyzed. Then, sound-insulation tests were conducted on different samples in the acoustic laboratory. The accuracy of the simulation model was verified through a comparative analysis of experimental results. Finally, based on the sound-insulation influence law of the sandwich panel core layer materials obtained from simulation analysis, the sound-insulation optimization design of the composite floor of a high-speed train was carried out. The results show that when the sound absorption material is concentrated in the middle, and the sound-insulation material is sandwiched from both sides of the laying scheme, it represents a better effect on medium-frequency sound-insulation performance. When this method is applied to the sound-insulation optimization of a high-speed train carbody, the sound-insulation performance of the middle and low-frequency band of 125-315 Hz can be improved by 1-3 dB, and the overall weighted sound reduction index can be improved by 0.9 dB without changing the type, thickness or weight of the core layer materials.

Restoring Voluntary Bimanual Activities of Patients with Chronic Hemiparesis through a Foot-Controlled Hand/Forearm Exoskeleton.

A significant number of stroke patients are permanently left with a hemiparetic upper limb after the poststroke six-month golden recovery period, resulting in a drastic decline in their quality of life. This study develops a novel foot-controlled hand/forearm exoskeleton that enables patients with hemiparetic hands and forearms to restore their voluntary activities of daily living. Patients can accomplish dexterous hand/arm manipulation on their own with the assistance of a foot-controlled hand/forearm exoskeleton by utilizing foot movements on the unaffected side as command signals. The proposed foot-controlled exoskeleton was first tested on a stroke patient with a chronic hemiparetic upper limb. The testing results showed that the forearm exoskeleton can assist the patient in achieving approximately 107°of voluntary forearm rotation with a static control error less than 1.7°, whereas the hand exoskeleton can assist the patient in realizing at least six different voluntary hand gestures with a success rate of 100%. Further experiments involving more patients demonstrated that the foot-controlled hand/forearm exoskeleton can help patients in restoring some of the voluntary activities of daily living with their paretic upper limb, such as picking up food to eat and opening water bottles to drink, and etc. This research implies that the foot-controlled hand/forearm exoskeleton is a viable way to restore the upper limb activities of stroke patients with chronic hemiparesis.

Electroactive Polymer-Based Soft Actuator with Integrated Functions of Multi-Degree-of-Freedom Motion and Perception.

Soft actuators have received extensive attention in the fields of soft robotics, biomedicine, and intelligence systems owing to their advantages of pliancy, silence, and essential safety. However, most existing soft actuators have only single actuation elements and lack sensing. Therefore, it is difficult for them to perform complex motions with multiple degrees of freedom (multi-DOFs) and high precision. This article reports a miniature columnar dielectric elastomer actuator (DEA) with multi-DOF actuation and sensing, which was fabricated with an electroactive polymer acrylic film (Very High Bond [VHB] acrylic film by 3M Company) and carbon black grease electrodes. The arrangement of the simulation electrodes on the VHB was optimized to realize multi-DOF actuation, and the sensing electrodes were configured on the outer part of the DEA to realize real-time sensing. The results showed that the soft actuator can achieve all-round actuation through the selective power of the stimulation electrodes with a controllable voltage. The maximum bending angle and axial strain of the actuator reached 50° and 13%, respectively. Moreover, the deformation modes, direction, and quantity could be precisely measured using the integrative sensing function. In addition, to demonstrate the advantages of the proposed actuator, a manipulator with multiple actuators was designed and controlled to realize different actions of screwing and grasping with sensing. This research is useful not only for the design of multifunctional soft actuators but also for the development of soft robots with flexible, complex, and precisely controllable motions.

Diagnosis after zooming in: A multilabel classification model by imitating doctor reading habits to diagnose brain diseases.

PURPOSE: Computed tomography (CT) has the advantages of being low cost and noninvasive and is a primary diagnostic method for brain diseases. However, it is a challenge for junior radiologists to diagnose CT images accurately and comprehensively. It is necessary to build a system that can help doctors diagnose and provide an explanation of the predictions. Despite the success of deep learning algorithms in the field of medical image analysis, the task of brain disease classification still faces challenges: Researchers lack attention to complex manual labeling requirements and the incompleteness of prediction explanations. More importantly, most studies only measure the performance of the algorithm, but do not measure the effectiveness of the algorithm in the actual diagnosis of doctors. METHODS: In this paper, we propose a model called DrCT2 that can detect brain diseases without using image-level labels and provide a more comprehensive explanation at both the slice and sequence levels. This model achieves reliable performance by imitating human expert reading habits: targeted scaling of primary images from the full slice scans and observation of suspicious lesions for diagnosis. We evaluated our model on two open-access data sets: CQ500 and the RSNA Intracranial Hemorrhage Detection Challenge. In addition, we defined three tasks to comprehensively evaluate model interpretability by measuring whether the algorithm can select key images with lesions. To verify the algorithm from the perspective of practical application, three junior radiologists were invited to participate in the experiments, comparing the effects before and after human-computer cooperation in different aspects. RESULTS: The method achieved F1-scores of 0.9370 on CQ500 and 0.8700 on the RSNA data set. The results show that our model has good interpretability under the premise of good performance. Human radiologist evaluation experiments have proven that our model can effectively improve the accuracy of the diagnosis and improve efficiency. CONCLUSIONS: We proposed a model that can simultaneously detect multiple brain diseases. The report generated by the model can assist doctors in avoiding missed diagnoses, and it has good clinical application value.

Development and challenges of smart actuators based on water-responsive materials.

Water-responsive (WR) materials, due to their controllable mechanical response to humidity without energy actuation, have attracted lots of attention to the development of smart actuators. WR material-based smart actuators can transform natural humidity to a required mechanical motion and have been widely used in various fields, such as soft robots, micro-generators, smart building materials, and textiles. In this paper, the development of smart actuators based on different WR materials has been reviewed systematically. First, the properties of different biological WR materials and the corresponding actuators are summarized, including plant materials, animal materials, and microorganism materials. Additionally, various synthetic WR materials and their related applications in smart actuators have also been introduced in detail, including hydrophilic polymers, graphene oxide, carbon nanotubes, and other synthetic materials. Finally, the challenges of the WR actuator are analyzed from the three perspectives of actuator design, control methods, and compatibility, and the potential solutions are also discussed. This paper may be useful for the development of not only soft actuators that are based on WR materials, but also smart materials applied to renewable energy.

[Association of Dietary Diversity with Growth and Development of Children in Multi-ethnic Rural Areas of Sichuan Province].

Objective To understand the growth and dietary diversity status of children in multi-ethnic areas of Sichuan province,and to explore the associations of dietary diversity with growth and development indicators. Methods Children of 18-36 months old and their primary caregivers were selected with multi-stage cluster random sampling method from rural areas of Han,Tibetan,and Yi ethnic groups in Sichuan province. The sociodemographic information of children and their caregivers was collected using self-designed questionnaire.The dietary diversity score(DDS)was calculated according to the criteria in the Guidelines for Measuring Household and Individual Dietary Diversity released by the Food and Agriculture Organization of the United Nations.The body height(length)and body weight of each child were measured by standard equipment for anthropological measurement,and the height for age Z score(HAZ),weight for age Z score(WAZ),and weight for height Z score(WHZ) were calculated.Multivariate linear regression was performed to analyze the relationship between dietary diversity and growth indicators of children. Results A total of 1092 children were enrolled in this study,and the prevalence of stunting(HAZ<-2),underweight(WAZ<-2),and wasting(WHZ<-2)was 21.1%,4.9%,and 2.5%,respectively.The children had the mean DDS of 4.8±1.7,and 45.3% of children had poor dietary diversity(DDS≤4).The children of Han ethnic group(5.8±1.4)had higher DDS than those of Tibetan ethnic group(4.9±1.6)and Yi ethnic group(3.9±1.6)(P<0.001).The results of multivariate linear regression indicated that DDS was positively correlated with HAZ(ß=0.206,95%CI=0.158-0.254,P<0.001)after adjustment of sex,age,birth weight,preterm birth,and parental body height.After further adjustment of family fixed assets,ethnic group,caregiver's type,and caregiver's education background,the correlation between DDS and HAZ remained significant(ß=0.077,95%CI=0.026-0.128, P=0.003). Conclusions The children in the multi-ethnic rural areas of Sichuan province showed troublesome growth and development status and low dietary diversity,which were conspicuously different between ethnic groups,especially in the rural areas of Yi ethnic group.The dietary diversity was positively associated with HAZ.It is recommended to carry out nutrition and health education according to the local dietary characteristics and thus improve the growth and development of children in multi-ethnic rural areas in Sichuan.

Correction: Distant Supervision for Mental Health Management in Social Media: Suicide Risk Classification System Development Study.

[This corrects the article DOI: 10.2196/26119.].

Distant Supervision for Mental Health Management in Social Media: Suicide Risk Classification System Development Study.

BACKGROUND: Web-based social media provides common people with a platform to express their emotions conveniently and anonymously. There have been nearly 2 million messages in a particular Chinese social media data source, and several thousands more are generated each day. Therefore, it has become impossible to analyze these messages manually. However, these messages have been identified as an important data source for the prevention of suicide related to depression disorder. OBJECTIVE: We proposed in this paper a distant supervision approach to developing a system that can automatically identify textual comments that are indicative of a high suicide risk. METHODS: To avoid expensive manual data annotations, we used a knowledge graph method to produce approximate annotations for distant supervision, which provided a basis for a deep learning architecture that was built and refined by interactions with psychology experts. There were three annotation levels, as follows: free annotations (zero cost), easy annotations (by psychology students), and hard annotations (by psychology experts). RESULTS: Our system was evaluated accordingly and showed that its performance at each level was promising. By combining our system with several important psychology features from user blogs, we obtained a precision of 80.75%, a recall of 75.41%, and an F1 score of 77.98% for the hardest test data. CONCLUSIONS: In this paper, we proposed a distant supervision approach to develop an automatic system that can classify high and low suicide risk based on social media comments. The model can therefore provide volunteers with early warnings to prevent social media users from committing suicide.

Ultrahigh-Sensitivity Molecular Sensing with Carbon Nanotube Terahertz Metamaterials.

Terahertz (THz) electromagnetic waves strongly interact with complex molecules, making THz spectroscopy a promising tool for high-sensitivity molecular detection, especially for biomedical applications. Metamaterials are typically used for enhancing THz-molecule interactions to achieve higher sensitivities. However, a primary challenge in THz molecular sensing based on metallic metamaterials is the limited tunability of optical constants of metals. Here, we present an ultrahigh-sensitivity molecular sensor based on carbon nanotube (CNT) THz metamaterials. The sensor, consisting of a CNT cut-wire array on a Si substrate prepared by a novel two-step method, exhibits a reflectance resonance whose frequency strongly varies with the substrate composition, geometries of periodic arrays, and analyte composition. We used this sensor to detect glucose, lactose, and chlorpyrifos-methyl molecules, achieving limit-of-detection values of 30, 40, and 10 ng/mL (S/N = 3), respectively, higher than that of metallic metamaterials by 2 orders of magnitude. We attribute this ultrahigh sensitivity to the high conductivity of CNTs and the efficient adsorption of the target analyte by CNTs through van der Waals forces and π-π stacking. These easy-to-fabricate CNT-based THz metamaterials pave the way for versatile and reliable ultrahigh-sensitivity THz molecular detection.

Recent Advances in Applications of Carbon Nanotubes for Desalination: A Review.

As a sustainable, cost-effective and energy-efficient method, membranes are becoming a progressively vital technique to solve the problem of the scarcity of freshwater resources. With these critical advantages, carbon nanotubes (CNTs) have great potential for membrane desalination given their high aspect ratio, large surface area, high mechanical strength and chemical robustness. In recent years, the CNT membrane field has progressed enormously with applications in water desalination. The latest theoretical and experimental developments on the desalination of CNT membranes, including vertically aligned CNT (VACNT) membranes, composited CNT membranes, and their applications are timely and comprehensively reviewed in this manuscript. The mechanisms and effects of CNT membranes used in water desalination where they offer the advantages are also examined. Finally, a summary and outlook are further put forward on the scientific opportunities and major technological challenges in this field.

Metallic mesh devices-based terahertz parallel-plate resonators: characteristics and applications.

The capability to design, fabricate, and optimize metamaterials based on various structures and material platforms has been crucial for the rapid development of modern terahertz (THz) technology. While the detailed structures of artificial unit cells within a metamaterial is certainly worth investigating, there has been increasing demand to integrate novel metamaterials with a traditional functional photonic device to form a hybrid device, whose performance is so significantly improved as to be promising for real-world applications. In this study, we proposed, for the first time, a THz parallel-plate resonator based on metallic mesh devices (MMDs) for chemical sensing applications. We studied the influences of various structural parameters through simulations, fabricated MMD-based resonator devices, and fully characterized the device performance through THz spectroscopy experiments. Furthermore, we experimentally demonstrated that our device can detect a doxycycline hydrochloride aqueous solution whose concentrations is as low as 1 mg L-1 through resonance frequency shifts, evidencing the device sensitivity capable of delicate chemical sensing tasks. Our work presents a practical and low cost architecture for chemical sensing using THz radiation, which opens new avenues for numerous useful THz devices based on metamaterials.

Mislocalization of Runt-related transcription factor 3 results in airway inflammation and airway hyper-responsiveness in a murine asthma model.

The Runt-related transcription factor (RUNX) gene family consists of three members, RUNX1, -2 and -3, which heterodimerize with a common protein, core-binding factor ß, and contain the highly conserved Runt-homology domain. RUNX1 and -2 have essential roles in hematopoiesis and osteogenesis. Runx3 protein regulates cell lineage decisions in neurogenesis and thymopoiesis. The aim of the present study was to determine the expression features of the Runx3 protein in a murine asthma model. In vivo, Runx3 protein and mRNA were found to be almost equivalently expressed in the murine lung tissue of the control, ovalbumin (OVA) and genistein groups; however, the nuclear Runx3 protein was abated in lung tissue in OVA-immunized and challenged mice. Following treatment with genistein, which is a flavonoid previously demonstrated to decrease airway inflammation in asthma, the allergic airway inflammation and airway hyper-responsiveness were attenuated and the Runx3 protein tended to augment in the nucleus. These results were further determined in vitro. These results indicated that the mislocalization of Runx3 protein is a molecular mechanism of allergic inflammation and airway hyper-responsiveness in a murine asthma model.