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Power-assisted lower limb exoskeleton robot is a wearable intelligent robot system involving mechanics, materials, electronics, control, robotics, and many other fields. The system can use external energy to provide additional power to humans, enhance the function of the human body, and help the wearer to bear weight that is previously unbearable. At the same time, employing reasonable structure design and passive energy storage can also assist in specific actions. First, this paper introduces the research status of power-assisted lower limb exoskeleton robots at home and abroad, and analyzes several typical prototypes in detail. Then, the key technologies such as structure design, driving mode, sensing technology, control method, energy management, and human-machine coupling are summarized, and some common design methods of the exoskeleton robot are summarized and compared. Finally, the existing problems and possible solutions in the research of power-assisted lower limb exoskeleton robots are summarized, and the prospect of future development trend has been analyzed. [ABSTRACT FROM AUTHOR]

The utilization of isolation systems employing Magnetorheological Elastomer (MRE) devices holds significant promise for structural vibration applications due to their customizable stiffness and damping characteristics. However, the nonlinear dynamics inherent in MRE isolators present formidable obstacles for the establishment of accurate models and development of effective control strategies for practical implementation. In this work, the dynamic properties of a self-made MRE isolator under different loading conditions are tested and analyzed. Then the nonparametric forward model and inverse model of MRE isolator based on BPNN (back propagation neural network) are established respectively, and the GA (genetic algorithm) is used to optimize the neural structure of BPNN. The precision and accuracy of the forward and inverse model is verified by comparing the predicted and experimental data. Simulation and experimental results show that the BPNN optimized by GA can efficiently and accurately model the nonlinear behavior of MRE isolators. Based on this, we take an eight-story shear frame building based on the proposed MRE vibration isolator model as the research object and numerically studied the vibration suppression effect under the control of three typical control algorithms, that is, LQR, FC, and FC-PID. In the process of evaluating the effect of vibration isolation control, in addition to utilizing the traditional displacement amplitude, layer distance and acceleration as evaluation indexes, we also propose a new comprehensive evaluation index which has weighting coefficients and considers the input cost. It is shown that the newly proposed comprehensive index can more conveniently compare the advantages and disadvantages of different control algorithms, and the fuzzy PID is the most suitable among the three control algorithms. [ABSTRACT FROM AUTHOR]

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In order to investigate the influence of sepiolite minerals on the normal force of magnetorheological grease (MRG), a mixed sample (ALCH) on the basis of preparing an aluminum–lithium-based magnetorheological grease (base sample ALC), containing sepiolite was further prepared. The field-dependent normal force of the two samples was tested using a rotational rheometer, considering conditions such as magnetic field, time, strain amplitude, frequency, and temperature, and the results were compared. The results indicate that sepiolite limits the field dependent normal force of the magnetorheological grease under steady state shear, and is unaffected by magnetic field, time, temperature, and shear rate. Sepiolite has minimal impact on the transient response of the magnetorheological grease. Under oscillatory shear, the magnetic field is an important factor influencing the field-dependent normal force response of the sepiolite-magnetorheological grease (ALCH). At low magnetic fields, the field-dependent normal force of the sepiolite-containing sample (ALCH) is greater than that of the base sample (ALC), while this relationship is reversed at high magnetic fields, unaffected by other factors. Under long-term shear conditions, both samples exhibit good shear stability, as well as consistency at different frequencies and strain amplitudes. However, an increase in shear rate reduces the normal force, and temperature also affects the field-dependent normal force. The patterns of variation in steady-state and oscillatory shear modes are not entirely the same, but both exhibit a characteristic decrease with increasing temperature under high magnetic field intensities. Sepiolite can reduce the temperature sensitivity of the normal force of the magnetorheological grease. In conclusion, the introduction of sepiolite is beneficial for the application of magnetorheology in high-precision devices. [ABSTRACT FROM AUTHOR]

As a biomarker, alpha-fetoprotein (AFP) is valuable for detecting some tumors in men, non-pregnant women, and children. However, the detection sensitivity in some methods needs to be improved. Therefore, developing a simple, reliable, and sensitive detection method for AFP is important for non-malignant diseases. An aptamer binding was developed based on aggregation-induced emission luminogen (AIEgen) nanosphere labeled with Fe3O4@MPTMS@AuNPs. AFP was detected with a sandwich structure of AuNPs magnetic composite particles. An aggregation-induced emission (AIE) molecule and polystyrene (PS) nanosphere complex were assembled, enhancing the fluorescence and improving the sensitivity of detection. The limit of detection (LOD) was at a given level of 1.429 pg/mL, which can best be achieved in serum samples. Finally, the results obtained showed the complex to be promising in practical applications. [ABSTRACT FROM AUTHOR]

Alpha-fetoprotein (AFP) is widely-known as the most commonly used protein biomarker for liver cancer diagnosis at the early stage. Therefore, developing the highly sensitive and reliable method of AFP detection is of essential demand for practical applications. Herein, two types of aptamer-based AFP detection methods, i.e., optical and electrochemical biosensors, are reviewed in detail. The optical biosensors include Raman spectroscopy, dual-polarization interferometry, resonance light-scattering, fluorescence, and chemiluminescence. The electrochemical biosensors include cyclic voltammetry, electrochemical impedance spectroscopy, and giant magnetic impedance. Looking into the future, methods for AFP detection that are high sensitivity, long-term stability, low cost, and operation convenience will continue to be developed. [ABSTRACT FROM AUTHOR]

Background: To investigate the expression of elastin in the conjoint facial sheath (CFS) in patients with severe unilateral congenital blepharoptosis in different age groups.Methods: Twenty-seven cases of severe unilateral congenital blepharoptosis (27 eyes) were treated with CFS + LM complex suspension from January 2020 to July 2020. Within that sample, 9 patients were over 18 years old, 9 patients were 13 to 17 years old and 9 patients were 5 to 12 years old. CFS and LM specimens were collected during CFS + LM complex suspension surgery. In the CFS specimens, the elastic fibers were observed by Victoria Blue staining. The elastin expression levels of the three groups of specimens were determined and analyzed by immunofluorescent staining and Western blotting.Results: Victoria Blue staining showed that elastic fibers were abundant in CFS tissue. Moreover, immunofluorescent staining showed strong positive expression of elastin in the CFS and LM. Furthermore, in the child group, the Western blot results demonstrated that the expression of elastin was higher in the CFS than in the LM (P < 0.05). Additionally, the expression of elastin was significantly higher in the CFS of children than in that of adults or adolescents (P < 0.001).Conclusions: The CFS and LM are rich in elastic fibers and elastin, although elastin expression in the CFS decreases with age. Thus, it is feasible to apply CFS + LM complex suspension to cure severe unilateral congenital blepharoptosis. [ABSTRACT FROM AUTHOR]

Elastin expression in the conjoint facial sheath (CFS) of patients of different ages with severe ptosis has been extensively studied, but its expression in the CFS of pediatric patients with severe ptosis with different muscle strengths remains poorly understood. The aim of the present study was to investigate the expression of elastin in the CFS and levator palpebrae superioris muscle (LM) of children with severe congenital ptosis with different LM strengths. In total, 20 pediatric patients with unilateral severe congenital ptosis (20 eyes) were included, who underwent CFS + LM complex suspension surgery from June 2020 to February 2022. Among these patients, the LM strength was 0-1 mm in 10 patients and 2-3 mm in the other 10 patients. Excess CFS and LM tissue samples were obtained from the patients during surgery, before the protein expression levels of elastin in the specimens were measured by western blotting. During the 6-month postoperative follow-up period, the good correction rate, the degree of incomplete eyelid closure and the incidence of complications were observed. Western blotting results showed that, compared with that in the 0-1 mm group, elastin expression was not significantly different in the CFS, whereas it was significantly increased (P=0.021) in the LM of the 2-3 mm group. In addition, elastin expression in the CFS was markedly higher compared with that in the LM in both groups (in the 0-1 mm group, P=0.005; in the 2-3 mm group, P=0.009). Additionally, the curative effect evaluation revealed that the good correction rates in the 0-1 and 2-3 mm groups were 90 and 100%, respectively. In total, 3 patients experienced conjunctival prolapse during the follow-up period, including 2 patients in the 0-1 mm group and 1 patient in the 2-3 mm group, but there were no other complications. To conclude, elastin expression in the CFS was found to be higher compared with that in the LM of children with severe congenital ptosis. Although elastin expression in the LM was positively associated with LM strength, its expression in the CFS displayed no clear association with LM function. Therefore, these observations suggested that CFS + LM complex suspension surgery is viable to correct severe congenital ptosis in pediatric patients. [ABSTRACT FROM AUTHOR]

In this paper, a new type of heavy-duty magnetorheological fluid (MRF) mount is proposed and experimentally investigated. The MRF mount with both annular and radial channels are based on two operating modes: flow mode and squeeze mode. The combined paths can lengthen the MRF valve and hence maximize the MR effect in flow mode. A mechanical model is established to institutively predict the maximum damping force that the device can achieve. Magnetic field distribution of the MRF mount is then evaluated based on finite element analysis. Both squeeze and flow regions can obtain magnetic field intensities up to 0.742 T and 0.7 T under 1 A current, respectively. Finally, the quasi-static and dynamic tests of MRF mount under different loading conditions (frequency, amplitude, current) are performed and the results showed that the proposed MRF mount can provide large damping force up to 18.843 kN and wide tunable range (719% increase on damping force at 0.1 Hz with 2 mm amplitude). [ABSTRACT FROM AUTHOR]

Neuropathic pain (NP) is chronic, intractable, and typically not alleviated using analgesics. Ferroptosis is a new type of cell death characterized by mitochondrial damage, oxidative stress, and mitochondrial dysfunction, affecting specific types of synaptic plasticity in the spinal cord. Here, we evaluated the role of ferroptosis in NP using chronic contractile injury (CCI) in rats. The CCI and control groups were subjected to sciatic nerve ligation. The mechanical withdrawal threshold and thermal withdrawal reflex latency were used to detect changes in mechanical pain threshold and thermal pain threshold in rats, respectively. Notably, CCI caused mechanical and thermal stimulation of the injured hind paw, reduced levels of glutathione peroxidase 4 (GPX4), and increased acyl-CoA synthetase long-chain family member 4 (ACSL4). Treatment with the ferroptosis inhibitor ferrostatin-1 (10 mg/kg) 1 h after surgery upregulated GPX4 expression and downregulated ACSL4 expression, whereas the ferroptosis inducer, erastin (10 mg/kg), exerted opposite effects. Treatment with ferrostatin-1 upregulated NeuN expression and downregulated GPX4 expression, whereas erastin reversed these effects. CCI increased the number of damaged mitochondria and decreased the mean planar mitochondrial area, and treatment with erastin further exacerbated these effects. The iron ion content in the spinal cords of CCI-induced rats increased. Treatment with ferrostatin-1 decreased, whereas treatment with erastin increased iron ion content in the CCI-induced rat model. Taken together, our results showed that ferroptosis is involved in the development of NP in male rats by blocking neuron and astrocyte activation in the spinal dorsal horn. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) grease, which is a type of magneto-sensitive smart material, exhibits complex viscoelastic behavior under different magnetic fields. Storage and loss moduli from oscillatory test are commonly used to characterize such field-dependent viscoelastic behavior. However, they are not able to represent the higher harmonic nonlinearity appeared in oscillatory responses under large amplitude oscillatory (LAOS) shear. In this paper, an investigation is conducted on the characterization of the filed-dependent nonlinearity of MR grease under LAOS by utilizing of Fourier transform (FT)-Chebyshev analysis. To capture the higher harmonic nonlinearity for the modeling and analysis, a comprehensive test program has been conducted. Firstly, MR grease with 70% weight percentage of carbonyl iron particles (MRG-70) is prepared and the stress response of MRG-70 under the oscillatory shear from small to large strain amplitudes with different magnetic field are measured. Then the higher harmonics in stress response signal are used to detect the intercycle nonlinearity of MRG-70 and compare with the traditional analysis method of dynamic modulus. Further, the elastic and viscous measures from FT-Chebyshev analysis are obtained to capture the inter-/intracycle nonlinear behaviors, that is, strain stiffening/softening, shear thickening/thinning, of MRG-70 under LAOS. It is found that, in the presence of magnetic fields, the onset of the intercycle nonlinearities of MRG-70 is originated from shear thickening of MR grease. With the further increase of the shear strain, MRG-70 exhibits the nonlinearities with different combinations of strain stiffening/softening and shear thickening/thinning. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) gel is a novel generation of smart MR material, which has the inherent hysteretic properties and strain stiffening behaviors that are dependent on applied excitation, i.e. magnetic field. The main challenge for the application of the MR gel is the accurate reproduction of the above characteristics by a computationally efficient model that can predict the dynamic stress-strain/rate responses. In this work, parametric modeling on the non-linear rheological behavior of MR gel is conducted. Firstly, a composite MR gel sample was developed by dispersing carbon iron particles into the polyurethane matrix. The dynamic stress-strain/rate responses of the MR gel are obtained using a commercial rheometer with strain-controlled mode under harmonic excitation with frequencies of 0.1 Hz, 5 Hz and 15 Hz and current levels of 1 A and 2 A at a fixed amplitude of 10%. Following a mini-review on the available mathematical models, the experimental data is utilized to fit into the models to find the best candidate utilizing a genetic algorithm. Then, a statistical analysis is conducted to evaluate the model's performance. The non-symmetrical Bouc–Wen model outperforms all other models in reproducing the non-linear behavior of MR gel. Finally, the parameter sensitivity analysis is employed to simplify the non-symmetrical Bouc–Wen model and then the parameter generalization is conducted and verified for the modified non-symmetrical Bouc–Wen model. [ABSTRACT FROM AUTHOR]

Background: Extensive studies revealed that long non-coding RNAs (lncRNAs) could act as a regulator in tumors, including lung adenocarcinoma (LUAD). LncRNA FTX transcript, XIST regulator (FTX) has been reported to regulate the biological behaviors of some cancers. Nevertheless, its functional role and molecular mechanism remain obscure in LUAD. Our current study concentrates on exploring the biological function of FTX in LUAD. Methods: RT-qPCR was used to test the expression of FTX, miR-335-5p or NUCB2 in LUAD cells. The effect of FTX on LUAD progression was investigated by colony formation, EdU, flow cytometry, TUNEL, transwell and western blot assays. The interaction between microRNA-335-5p (miR-335-5p) and FTX or nucleobindin 2 (NUCB2) was confirmed by luciferase reporter assay. Results: RT-qPCR showed that FTX expression was up-regulated in LUAD cell lines. Loss-of-function assay indicated that FTX accelerated cell proliferation, migration and invasion, while inhibited cell apoptosis in LUAD. Besides, miR-335-5p, lowly expressed in LUAD cells, was discovered to be sponged by FTX. Subsequently, NUCB2 was identified as a target gene of miR-335-5p. Additionally, it was confirmed that NUCB2 functioned as an oncogene in LUAD. Rescue assays indicated that LUAD progression inhibited by FTX knockdown could be restored by NUCB2 up-regulation. Conclusion: FTX played an oncogenic role in LUAD and contributed to cancer development via targeting miR-335-5p/NUCB2 axis. [ABSTRACT FROM AUTHOR]

Aim: The current work highlighted a novel colorimetric sensor based on aptamer and molybdenum disulfide (MoS2)-gold nanoparticles (AuNPs) that was developed for cocaine detection with high sensitivity. Materials & methods: Due to the presence of the plasmon resonance band on the surface of AuNPs, AuNPs aggregated and the color was changed from red to blue after adding a certain concentration of NaCl. We used MoS2 to optimize the sensing system of AuNPs. The folded conformation of the aptamer in combination with cocaine enhanced the salt tolerance of the MoS2-AuNPs, effectively preventing their aggregation. Results & conclusion: The detection limit of cocaine was 7.49 nM with good selectivity. The method based on MoS2-AuNPs colorimetry sensor is simple, quick, label-free and low cost. [ABSTRACT FROM AUTHOR]

In this study, a thiol-modified aptamer was immobilized on a gold nanoparticle-modified molybdenum disulfide composite material (MoS2@AuNPs), which could remove the interference of physical adsorption and reduce false positive signals. Furthermore, a non-fluorescent dual-thiol aptamer was immobilized on the surface of MoS2@AuNPs with a low background signal. After attaching the cocaine using a dual-thiol aptamer immobilized on the surface of MoS2@AuNPs, cocaine could be detected using a cocaine aptamer with 5-carboxyfluorescein (FAM). The aptamer–cocaine–aptamer complex was used to form a fluorescence signal, which made the signal noise (S/N) relatively high and sensitive to cocaine detection with 0.54 pM. Under optimal conditions, the change in the fluorescence intensity of the sensor was proportional to the concentration of cocaine in the range of 0–0.1 nM. This experiment was carried out in a human serum sample, and results showed that the analysis of cocaine using this sensor was promising. [ABSTRACT FROM AUTHOR]

In order to investigate the multiphysics in the recoil process of magnetorheological damper, independent three-stage magnetorheological damper of double rod has been designed. The magnetorheological gel with carbonyl iron powder mass fraction of 70% (MRG-70) has been prepared and the steady-state shear test was carried out for obtaining the consistency coefficient k and the non-Newtonian index n of the Herschel–Bulkley model. MRG-70 has been applied to the damper and the motion analysis of the recoil part has been carried out by combining the law of chancing of the bore resultant force of a certain type of fixed artillery. Results of the theoretical analysis and numerical calculation of multiple physical fields for damper showed: (1) there was a scattered magnetic flux inside the damper. The magnetic field was generated by the combined coil with a high degree of nonlinearity and time variability; (2) the internal energy dissipation of damper comprises five parts, in which Poiseuille pressure flow loss and Couette viscous flow loss were the primary and controllable part of the damper. The temperature of each pole reaches a peak value, and it is different at different times; the pressure drop at the magnetic pole was less than the pressure drop at the coil; (3) the dynamic viscosity of the central axial surface of the effective damping channel shows obvious nonlinearity and time variability from the spatial and time dimension, and varies very sharply at each pole, and the peak value fluctuates with the position. [ABSTRACT FROM AUTHOR]

Background. Neuropathic pain is a chronic and intractable pain, with very few effective analgesics. It involves an impaired cell autophagy process. Hydrogen-rich saline (HRS) reportedly reduces allodynia and hyperalgesia in a neuropathic pain model; however, it is unknown whether these effects involve autophagy induction. Methods. We investigated the relationship between HRS and cell autophagy in a neuropathic pain model generated by chronic constriction injury (CCI) in Sprague–Dawley rats. Rats received an intraperitoneal injection of HRS (10 mL/kg daily, from 1 day before until 14 days after CCI), 3MA (autophagy inhibitor), 2ME2 (HIF-1α inhibitor), or EDHB (HIF-1α agonist). The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were tested 1 day before and 1, 3, 7, 10, and 14 days after the operation. HIF-1α and cell autophagy markers in the spinal cord were evaluated by western blotting and real-time PCR assays at 14 days after CCI. Autophagosomes with double membranes were identified by transmission electron microscopy. Results. CCI caused behavioral hypersensitivity to mechanical and thermal stimulation in the hind-paw of the injured side. HRS improved MWT and TWL, activated autophagy, and increased autophagosomes and autolysosomes in CCI rats. 3-MA aggravated hyperalgesia and allodynia and suppressed autophagy, while EDHB attenuated hyperalgesia and activated the autophagy procedure and the HIF-1α downstream target gene BNIP3. HIF-1α inhibitors reversed the regulatory effects of HRS on autophagy in CCI rats at 14 days after spinal cord injury. Conclusion. HRS reduced mechanical hyperalgesia and activation of cell autophagy in neuropathic pain through a HIF1-dependent pathway. [ABSTRACT FROM AUTHOR]

This paper investigates the quasi-static rheological properties of lithium-based magnetorheological (MR) grease under large deformation. Three types of lithium-based MR grease comprising different mass ratios of carbonyl iron (CI) particles and lithium-based grease were prepared. The dependence of the magneto-induced stress–strain curves for MR grease on CI particles content, shear rate, and shear deformation under quasi-static monotonic shear conditions were tested and discussed. The results demonstrate that the shear rate dependence of the maximum yield stress is significantly weakened by the magnetic field, and this weakening is further enhanced as the CI particles content of MR grease increases. In addition, to evaluate and characterize the behavior of the cyclic shear–stress curves of MR grease under quasi-static condition, cyclic shear tests under different controlled conditions, i.e., CI particles content, shear rate, shear strain amplitude, and magnetic field strength, were conduct and analyzed. The magneto-induced shear stress of MR grease with higher CI particles content shows a sharp decrease during the transition from loading to unloading. Moreover, the experiment results also show that the damping characteristics of MR grease are highly correlated with CI particles content, shear strain, and magnetic field strength. [ABSTRACT FROM AUTHOR]

As a kind of new MR material, MR gel (MRG) can be regard as the analog of MRF, which can overcome the iron particles sedimentation and unstable application of MRF especially in recoil of gun. However, some major parameter of this kind of MRG, such as the initial modulus, magneto-induced shear storage modulus and relative MR effect are relatively small, which cannot meet the need the application in recoil of gun. In this work, an MRG with high magneto-induced shear storage modulus, relative MR effect and suitable initial modulus has been fabricated by controlling the mass fraction of carbonyl iron powder (CIP) under specific crosslinking degree of polyurethane (PU) matrix. And several PU-based MRG composites with the CIP mass fraction of 40, 60, 80% were prepared. The dynamic mechanical property of those MRG samples ware researched through an advanced commercial rheometer. The experimental results indicated that magneto-induced modulus and relative MR effect in sample 2 (containing 60 wt% of CIP) were approximately 2.87 and 2.32 times than sample 1 (containing 40 wt% of CIP), 1.67 and 2.97 times than sample 3 (containing 80 wt% of CIP). Moreover, the samples have good consistency in transient response under the step magnetic field. The high magneto-induced modulus of sample 2 can be mainly attributed to the following point. Appropriate amount of PU polymer chain can reinforce the binding force between CIPs in the chain and better constrained particle motion under magnetic field. It is concluded that this study provides a meaningful way to improve the mechanical properties of MRG and expected to promote the application of MRG in recoil of gun. [ABSTRACT FROM AUTHOR]