Sodium alginate/sodium lignosulfonate hydrogel based on inert Ca2+ activation for water conservation and growth promotion.

Soil degradation has become a major global problem owing to the rapid development of agriculture. The problems of soil drought and decreased soil fertility caused by soil degradation severely affect the development of the agricultural and forestry industries. In this study, we designed sodium alginate (SA)/sodium lignosulfonate (SLS) hydrogel based on the activation and crosslinking of inert Ca2+. CaCO3 and SA were mixed, and then, inert Ca2+ was activated to prepare a gel with a stable structure and a uniform interior and exterior. The crosslinking activated by inert Ca2+ enhanced the stability of the hydrogel, and the optimal swelling rate of the hydrogel reached 28.91 g/g, thereby effectively improving the water-holding capacity of the soil (77.6-108.83 g/kg). SLS was degraded into humic acid (HA) and gradually released, demonstrating a positive growth-promoting effect in plant growth experiments. The SA/SLS hydrogel can be used for soil water retention and mitigation to significantly decrease the water loss rate of soil. This study will assist in addressing soil drought and fertility loss.

RGO-Induced Flower-like Ni-MOF In Situ Self-Assembled Electrodes for High-Performance Hybrid Supercapacitors.

Currently, the primary bottlenecks that hinder the widespread application of supercapacitors are low energy density and narrow potential windows. Herein, the hybrid supercapacitor with high energy density and wide potential window is constructed via an in situ self-assembly method employing RGO-induced flower-like MOF(Ni). Benefiting from the synergistic effect between RGO and MOF(Ni), the interfacial interactions are effectively improved, and the contact area with the electrolyte is enhanced, which increases the ion transfer kinetics and overall electrochemical performance. The MOF(Ni)@RGO electrode exhibits a specific capacitance of 1267.73 F g-1 at a current density of 1 A g-1. Crucially, the assembled MOF(Ni)@RGO//BC with a broad potential window and good stability employing a MOF(Ni)@RGO anode and biomass carbon cathode, combined with a 2 M PVA-KOH gel-electrolyte, achieves a maximum energy density of 70.16 Wh kg-1 at a power density of 2200.09 W kg-1, outperforming most reported supercapacitors. This hybrid supercapacitor exhibits excellent stability and high energy density, providing a novel strategy for further large-scale applications.

Digital twin rehabilitation system based on self-balancing lower limb exoskeleton.

BACKGROUND: The digital twin concept is the virtual model based on entity design measures, which is used in many enterprises' virtual workshop design models for workshop production scheduling and optimization. However, in the field of medical rehabilitation, the integration of digital twin technology started late compared to traditional industrial manufacturing. Many current digital models are not well suited for information interaction between patients and devices. OBJECTIVE: In order to address the lack of interaction between patients and devices in the field of medical rehabilitation, this paper proposes an automatic gait data control system (AGDCS) for fully actuated lower limb exoskeleton digital twinning. This system improves the integration of digital twinning system with the medical rehabilitation field and analyzes the patient's gait data through simulation experiments. METHODS: The digital twin system was designed in several steps. Firstly, the upper computer function module was designed and developed according to the rehabilitation treatment needs. After that, the combination of exoskeleton robot and software was carried out, and finally the real rehabilitation treatment environment of patients was simulated through experiments. RESULTS: The proposed system was very reliable in the experimental tests of the host computer and exoskeleton robot. In the upper computer test, the patient specific gait can be generated, and the motion of the exoskeleton robot can be observed in real-time. During the walking test of the exoskeleton robot, the exoskeleton robot completed the specified gait. The result verified the superiority and effectiveness of the digital twin system AGDCS in the field of rehabilitation. CONCLUSIONS: The digital twin system proposed in this paper improves the interaction between self-balancing exoskeleton robot and patients, and improves the autonomy and safety of patients in rehabilitation treatment.

Design and analysis of a lightweight lower extremity exoskeleton with novel compliant ankle joints.

BACKGROUND: The exoskeleton for lower limb rehabilitation is an uprising field of robot technology. However, since it is difficult to achieve all the optimal design values at the same time, each lower extremity exoskeleton has its own focus. OBJECTIVE: This study aims to develop a modular lightweight lower extremity exoskeleton (MOLLEE) with novel compliant ankle joints, and evaluate the movement performance through kinematics analysis. METHODS: The overall structure of the exoskeleton was proposed and the adjustable frames, active joint modules, and compliant ankle joints were designed. The forward and inverse kinematics models were established based on the geometric method. The theoretical models were validated by numerical simulations in ADAMS, and the kinematic performance was demonstrated through walking experiments. RESULTS: The proposed lower extremity offers six degrees of freedom (DoF). The exoskeleton frame was designed adjustable to fit wearers with a height between 1.55 m and 1.80 m, and waist width from 37 cm to 45 cm. The joint modules can provide maximum torque at 107 Nm for adequate knee and hip joint motion forces. The compliant ankle can bear large flexible deformation, and the relationship between its angular deformation and the contact force can be fitted with a quadratic polynomial function. The kinematics models were established and verified through numerical simulations, and the walking experiments in different action states have shown the expected kinematic characteristics of the designed exoskeleton. CONCLUSIONS: The proposed MOLLEE exoskeleton is adjustable, modular, and compliant. The designed adjustable frame and compliant ankle can ensure comfort and safety for different wearers. In addition, the kinematics characteristics of the exoskeleton can meet the needs of daily rehabilitation activities.

Kinematics study of a 10 degrees-of-freedom lower extremity exoskeleton for crutch-less walking rehabilitation.

BACKGROUND: Wearable lower extremity exoskeletons can provide walking assistance for the physical rehabilitation of paralyzed individuals. However, most of the existing exoskeletons require crutches to maintain balance, thus a self-balancing type is needed to improve applicability. OBJECTIVE: The purpose of this work is to study the kinematic characteristics of a novel lower extremity exoskeleton for crutch-less walking rehabilitation, and evaluate the movement performance through practical experiments. METHODS: Based on the human lower limb structure and movement characteristics, a fully actuated 10 degrees-of-freedom (DoF) lower extremity exoskeleton was proposed. The kinematic characteristics of the exoskeleton were analyzed by the D-H method and geometric method, and the model validity was verified through simulations and experiments. RESULTS: The closed-form solutions for both forward and inverse kinematics models were obtained. The consistent results of theoretical calculation and numerical simulation have shown the accuracy of the established models. The practical experiments regarding six trials have demonstrated the movement performance of the proposed exoskeleton, including sit, stance, leg extension/flexion, and left/right swing. CONCLUSIONS: The kinematic characteristics of the proposed 10-DoF lower extremity exoskeleton are similar to the human lower limb, and it could meet the motion demands of crutch-less walking rehabilitation.