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Purpose: The purpose of this study is to characterize the effect of sex and the influence of oral contraception usage on musculotendinous injury (MTI). Current literature suggests a disparity in the incidence of MTI between males and females. This may be attributed to inherent biological differences between the sexes, such as in the sex hormonal milieu. There is a lack of information associating sex hormone milieu and MTI. Methods: We searched the PearlDiver database (a for-fee healthcare database) for males, females taking oral contraceptives (OC), and eumenorrheic females not taking any form of hormonal contraceptives (non-OC) 18–39 yr old. The three populations were matched by age and body mass index. We queried the database for lower-extremity skeletal MTI diagnoses in these groups. Results: Each group contained 42,267 patients with orthopedic injuries. There were a total of 1476 (3.49%) skeletal MTI in the male group, 1078 (2.55%) in non-OC females, and 231 (0.55%) in OC females. Both the non-OC and the OC groups had a significantly smaller proportion of MTI than males (P < 0.0001), and therefore these groups were less likely (adjusted odds ratios, 0.72 and 0.15, respectively) to experience MTI when controlled for potential covariates. Conclusions: In this study, we show that females are less likely to develop MTI to total injuries, when compared with males, with OC using females being least likely followed by non-OC females. These results are consistent with other epidemiological studies; however, overall results in the literature are variable. This study adds to the emerging body of literature on sex hormone–influenced musculoskeletal injury but, more specifically, MTI, which have not been rigorously investigated. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to improve the corrosion resistance of the 6061-Al alloy as the battery pack material for electric vehicles, and the nano-SiC/MAO composite coating was prepared. Design/methodology/approach: The corrosion resistance of coatings was evaluated by the global electrochemical test, and the local electrochemical impedance spectroscopy (LEIS) was used to study the local corrosion mechanism. The laser confocal microscope, scanning electron microscope and X-ray diffractometer (XRD) were used to characterise coatings. Findings: Results showed that the impedance of nano-SiC/MAO coating was 1–2 times higher than MAO coating, and the main corrosion product was Al(OH)3. LEIS results showed that the impedance of the nano-SiC/MAO coating was two times higher than the MAO coating. The defective SiC/Micro-arc oxidation coating still had high corrosion resistance compared to the MAO coating. Originality/value: The physical model of the local corrosion mechanism for SiC/MAO composite coating in "cavity-fracture collapse" mode was proposed. [ABSTRACT FROM AUTHOR]

With the increasing development of infrared (IR) detection technologies for both military and civil applications, IR anti‐detection technologies, also known as thermal camouflage technologies, have attracted great attention in recent years. Decreasing the surface emissivity may be effective for high‐temperature targets, but fails for adaptive thermal camouflage in dynamic scenes where the background temperature varies. In this work, we demonstrate a flexible Janus functional film (JFF) for adaptive thermal camouflage. The JFF consists of a low emissivity (low‐ε) layer and a high heat capacity (high‐C) layer. The low‐ε layer can effectively suppress the IR radiation of the objects, thus reducing the temperature of the objects in IR camera, while the high‐C layer can make similar thermal response as the background. According to different environmental conditions, different surfaces of JFF can be selected as camouflage surface to achieve static or dynamic thermal camouflage effect. What's more, the substrate materials of JFF (i.e., high‐density polyethylene (HDPE), silica gel (SG)) enable the film with good flexibility and realize the encapsulation of the functional filler, thus improving its reliability of resisting water and oxygen. Such flexible JFF with high reliability, easy scalability, and low cost may hold great promise for broad applications in adaptive thermal camouflage. [ABSTRACT FROM AUTHOR]

In this decade, the demands of energy saving and diverse personal thermoregulation requirements along with the emergence of wearable electronics and smart textiles give rise to the resurgence of personal thermal management (PTM) technologies. PTM, including personal cooling, heating, insulation, and thermoregulation, are far more flexible and extensive than the traditional air/liquid cooling garments for the human body. Concomitantly, many new advanced materials and strategies have emerged in this decade, promoting the thermoregulation performance and the wearing comfort of PTM simultaneously. In this review, an overview is presented of the state‐of‐the‐art and the prospects in this burgeoning field. The emerging materials and strategies of PTM are introduced, and classed by their thermal functions. The concept of infrared‐transparent visible‐opaque fabric (ITVOF) is first highlighted, as it triggers the work on advanced PTM by combining it with radiative cooling, and the corresponding implementations and realizations are subsequently introduced, followed by wearable heaters, flexible thermoelectric devices, and sweat‐management Janus textiles. Finally, critical considerations on the challenges and opportunities of PTM are presented and future directions are identified, including thermally conductive polymers and fibers, physiological/psychological statistical analysis, and smart PTM strategies. [ABSTRACT FROM AUTHOR]

Reactive graphene oxide (GO) with multiple carboxyls or hydroxyls was well dispersed in a liquid silicon‐containing cycloaliphatic diepoxide. Upon heating the mixture gradually to 180°C, GO was in situ copolymerized with diepoxide to produce novel graphene/epoxy nanocomposites with the GO contents varied from 0 to 5 wt%. Fourier transform infrared spectra demonstrate that the reactive groups of GO have participated in the polymerization reaction. The composites thus obtained have similar amorphous wide‐angle X‐ray diffraction patterns to the pure epoxy resin, whereas the peak at 9.54° corresponding to GO aggregations is absent, indicating a homogeneous dispersion of GO within epoxy matrix, which is consistent with the scanning electron microscopy and transmission electron microscopy observations. The influence of the GO incorporation on dielectric properties, viscoelastic behaviors, glass transition temperatures, and thermal stability of GO/epoxy nanocomposites is systematically investigated by means of impedance analyzer, dynamic mechanical analysis, and thermal gravimetric analysis. The results show that the dielectric permittivities (k) of the samples significantly increase from 5.0 to 55 with the GO contents, and the k values are stable in the frequency range up to 1 MHz. The high dielectric permittivity and excellent dielectric stability are extremely important for the fabrication of high‐performance electronic devices. [ABSTRACT FROM AUTHOR]

The effect of the addition of different concentrations of Cu2+, Fe2+, and Fe3+ on the micromorphology and crystalline structure of CaCO3 fouling was studied using the VHX-500FE digital microscope and X-ray diffraction. Results indicate that the fouling morphology becomes stubby and forms a cluster and the fouling color deepens with the increase in the concentration of metal ions. Furthermore, the relative content of aragonite increases and that of calcite decreases. Fe2+ plays a more important role in the inhibition of calcite than Fe3+ when scaling occurs in the boiling system under the condition of atmospheric environment. The reason may be that O2 participates in the inhibition process. Fe2+ and Fe3+ promote atomic transition and crystal defects, and this condition changes the absorption wavelength of fouling. Carbon steel and copper samples were immersed in test solution for 28 h as a comparative experiment. This experiment indicates that corrosion may release metal ions, which further affect the fouling morphology and phase component content in the long-term fouling process. In conclusion, fouling weight method for measuring anti-fouling property can only be used to compare materials with similar anti-corrosion property. [ABSTRACT FROM AUTHOR]

Background: Early dislocation following primary total hip arthroplasty (THA) is a rare but devastating complication and represents a source of patient morbidity and financial burden to the healthcare system. The objective of this study was to identify patient characteristics and comorbidities that are associated with increased early in-hospital dislocation rates following primary THA. Methods: A retrospective cohort study was conducted using patient data from the Nationwide Inpatient Sample (NIS) database; we identified patients who had undergone THA from 2016 to 2019 and compared those with an early periprosthetic dislocation prior to discharge to those without. The patient characteristics and comorbidities were compared using univariate analysis with a subsequent investigation of statistically significant variables using multivariate analysis. The variables were compared using chi square, Fisher's exact test, and independent sample t-tests with data assessed using odds ratio with 95% confidence intervals. Results: A total of 5151 patients sustained an early dislocation compared to 362,743 who did not. Those who sustained an in-hospital dislocation were more likely to share the following characteristics: female sex (OR 1.21, p < 0.01), age > 70 (OR 1.45, p < 0.01), Caucasian ethnicity (OR 1.22, p < 0.01), SLE (OR 1.87, p < 0.01), and Parkinson's disease (OR 1.93, p < 0.01). Certain characteristics were also associated with decreased odds of having an in-hospital dislocation including elective surgery (OR 0.14, p < 0.01), tobacco use (OR 0.8, p < 0.01), diabetes without complications (OR 0.87, p < 0.01), and a history of heart valve replacement (OR 0.81, p < 0.01). The length of stay was significantly longer (4.7 days vs. 2.3 days) as was the total hospital charges (USD $101,517 vs. USD $66,388) for the early in-hospital dislocation group. Conclusions: Several patient characteristics and comorbidities are associated with early in-hospital dislocation episodes following total hip arthroplasty including female sex, age > 70, non-elective surgery, SLE, and Parkinson's. This information may be useful to help guide intraoperative implant selection and/or postoperative protocol in select patient populations to limit early instability as well as decrease the financial burden associated with this postoperative complication. [ABSTRACT FROM AUTHOR]

With the advent of thermal metamaterials, many new thermal functionalities have been proposed, like thermal cloaking, concentrating, etc. However, these thermal functionalities are based on the transformation thermotics or scattering cancellation technique, which, derived from Fourier's law, cannot apply to the micro-/nanoscale counterparts. In this paper, we design a nanoscale thermal cloak based on a crystalline silicon (Si) membrane and investigate the in-plane phonon transport via non-equilibrium molecular dynamics (NEMD) simulation by in-situ tuning the thermal conductivity of the thermal cloak from crystalline Si to amorphous Si. The two-dimensional temperature profile is obtained, and the thermal cloaking effect is evaluated by the ratio of heat flux. By analyzing the phonon density of state (PDOS) and the mode participation ratio (MPR), the mechanism can be attributed to the phonon localization in the annealed cloaking region. The proposed nanoscale thermal cloak by in-situ tuned thermal conductivity, may trigger the development of nanoscale thermal functionalities and open avenues for and thermal management for nano-photonics and nano-electronics. • We design a nanoscale thermal cloak with in-site tuned thermal conductivity. • Thermal cloaking effect is positively proportional to the width of the cloak ring. • Phonon localization and non-propagating diffusive mode are attributed. [ABSTRACT FROM AUTHOR]

WNT/β-catenin signaling is crucial to all stages of life. It controls early morphogenetic events in embryos, maintains stem cell niches in adults, and is dysregulated in many types of cancer. Despite its ubiquity, little is known about the dynamics of signal transduction or whether it varies across contexts. Here we probe the dynamics of signaling by monitoring nuclear accumulation of β-catenin, the primary transducer of canonical WNT signals, using quantitative live cell imaging. We show that β-catenin signaling responds adaptively to constant WNT signaling in pluripotent stem cells, and that these dynamics become sustained on differentiation. Varying dynamics were also observed in the response to WNT in commonly used mammalian cell lines. Signal attenuation in pluripotent cells is observed even at saturating doses, where ligand stability does not affect the dynamics. TGFβ superfamily ligands Activin and BMP, which coordinate with WNT signaling to pattern the gastrula, increase the β-catenin response in a manner independent of their ability to induce new WNT ligand production. Our results reveal how variables external to the pathway, including differentiation status and cross-talk with other pathways, dramatically alter WNT/β-catenin dynamics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simple surface treatment by steam improves adhesive bonding of aluminum remarkably. • High-resolution 3D imaging of the interfaces by STEM-tomography and STEM-EELS were performed for elucidate the mechanism. • Chemical interactions at aluminum/adhesive interfaces was proposed. A simple surface treatment by steam on aluminum substrate can enhance the bonding strength with epoxy adhesives. We studied the mechanism of the effect of steam on adhesive bonding by using scanning transmission electron microscopy coupled with electron energy loss spectroscopy (STEM-EELS). The observed increase of adhesion strength was achieved by diffusion of the adhesive molecules into the nanopores of the aluminum surface, which switched the failure mode from interfacial failure to cohesive failure. Investigation of electron energy loss near edge fine structure (ELNES) in EELS allows us to find chemical bonding that form via acid–base interactions between the amino moiety of the adhesive and the hydroxyl groups on the aluminum surface. This weak bonding may not contribute directly to the increase of adhesion strength, but it induces spontaneous diffusion of the adhesion molecules into the pores via thermodynamically favored acid–base interfacial interactions. [ABSTRACT FROM AUTHOR]

The nano-scale failure behaviors of joint interfaces were investigated by in-situ straining technique to observe the crack propagations in a transmission electron microscope (TEM). The thin sections of bonded interfaces were subjected to tensile loading by using a specially designed specimen holder. The deformation at the crack tip before the initiation of crack and the initiation of the crack were observed in the nanometer level. The experiments with identical and dissimilar polymer/polymer welded specimens allowed us to see the plastic deformation ahead of the crack tip and the creation of craze, which is the typical failure mode of polymers. The failure of the interfaces between aluminum alloy (Al5052) and epoxy adhesive and between Al5052 and thermoplastic directly bonded by injection molding were investigated to visualize the failure behaviors in small scale before the macroscopic fracture of the interfaces. The in-situ straining technique under a high-resolution scanning transmission electron microscopy (STEM) mode enables the observation of micro deformation ahead of the crack, microvoids produced prior to the crack progression and the failure of the surface modified layer on Al surface. [ABSTRACT FROM AUTHOR]

Abstract: Liquid cycloaliphatic diepoxide containing sulfite group (Epoxide-S) was designed and synthesized through the two-step reactions: the nucleophilic substitution between thionyl chloride and cyclohex-3-1-methanol, and the subsequent epoxidation. The chemical structures of the epoxidized product and its olefin precursor were confirmed by FTIR and 1H NMR spectra. Different from conventional thermosetting epoxy resins, the cured Epoxide-S started to decompose at 185 °C. The apparently lower degradable temperature is desirable for reworkable electronic packaging materials because the dismantlement of waste electronic products or the replacement and repair of faulty chips become convenient. Moreover, after co-curing between Epoxide-S and the commercial cycloaliphatic diepoxide ERL-4221, the thermal degradation temperatures of the copolymers were tunable in the range from 185 to 323 °C by varying the ratio of two monomers. The unique degradation behaviors were investigated by means of computer calculation, thermogravimetric analysis, and FTIR spectra. [Copyright &y& Elsevier]

Abstract: Fouling adhering experiments on AISI 304 stainless steel surfaces with different roughness had been performed in boiling supersaturated calcium bicarbonate solution. The effect of surface roughness on adhesion of fouling is limited, and the adhesion of fouling does not have a simple linear relationship with the surface roughness of samples. The surface with roughness in middle is more easily induced to form “transitional interface” which connects the fouling and matrix surface. It is also found that the crystalline types of fouling are changed in the fouling process due to the variation of metallic ions in reaction solution. [Copyright &y& Elsevier]

Radiative cooling, which aims at cooling objects by radiating heat into the outer space through the atmosphere window, has garnered wide interests since it is a passive refrigeration mode without extra energy consumption. However, most of the proposed structures, to maximize the cooling performance, are in white color, which may limit their practical applications due to some aesthetic consideration. To reveal the competing role between color display and radiative cooling performance, we take a metal-dielectric-metal (MDM) colored radiative cooler structure as representative to explore how the structure parameters influence the cooling performance and color display respectively, and clarify the key parameters for the desired performance. Moreover, the reflectance of the colored radiative cooler is identified as peak- and valley-types to clarify the color display performance. The Spearman rank order correlation coefficients between radiative cooling performance and the CIE-LCH color space parameters (lightness, chroma, and hue) are calculated, revealing that the lightness plays a dominant role. The present study is expected to reveal the competing role of radiative cooling power and color display, and trigger the practical applications of radiative cooling technologies. • A colored radiative cooler with a metal-dielectric-metal structure is proposed. • The competing role between color display and radiative cooling power is revealed. • Lightness plays a more dominant role than chroma and hue for colored radiative cooling. [ABSTRACT FROM AUTHOR]

• Nanogel particles are deposited onto carbon paper by a spray coating method. • CO 2 adsorption-desorption experiments are performed in a milli-channel reactor. • The adsorbent exhibits fast CO 2 adsorption rate and desorption rate. • The adsorbent presents good stability under wet conditions. In this work, we report a proof-of-concept study on CO 2 adsorbents synthesized by a thermally initiated free-radical copolymerization and then coated onto carbon paper and poly tetra fluoroethylene via a spray coating approach. A milli-channel reactor was employed to support the obtained materials for efficient CO 2 capture with wet conditions, short cooling and heating cycles (303–348 K). CO 2 uptake and release performance of the materials were measured and compared with that of the polyamine-based materials prepared by other methods. CO 2 adsorption and desorption kinetics can be greatly enhanced when using the spray coating approach, especially for carbon paper as supporter. The CO 2 adsorption capacity of the spray-coated carbon paper reaches 80% of its maximum value in only 4.37 ± 0.7 min. Moreover, its adsorption rate (114.6 mg/(g∙min) at 303 K) and desorption rate (239.9 mg/(g∙min) at 348 K) were 81.2% and 81.5% higher than those of the polyamine-impregnated carbon paper, respectively (12% CO 2 at atmospheric pressure). Their largest increases of 71% and 67% were achieved by adjusting the concentration of polyamine nanogel particles deposited on the carbon paper surface. The prepared material also presents stable recyclability over 10 wet adsorption–desorption cycles and the aging experiments. The results obtained in this study indicate that the synthesized materials can serve as promising energy-efficient solid adsorbents for CO 2 capture. [ABSTRACT FROM AUTHOR]

• Nanogel particles for CO 2 capture with lower cycles (303–348 K) are developed. • Carbon paper as supporter shows higher CO 2 capacity, adsorption and desorption rate. • Avrami's fractional order model accurately predicts the CO 2 uptake behaviors. • The CO 2 capture process is governed by film and intraparticle diffusion resistance. • Carbon paper as supporter shows lower sensible heat and desorption activation energy. Amine-containing nanogel particles with a lower cooling and heating cycles (303–348 K), which is beneficial to limit the degradation and volatile of amine, has been developed as promising absorbents for CO 2 capture. It is extremely important to understand the CO 2 capture kinetics and mechanisms for design and operation of corresponding processes. In present work, poly tetra fluoroethylene and carbon paper were used to support the GPs by filtering and loading method. The CO 2 uptake and release performance of poly tetra fluoroethylene and carbon paper supported nanogel particles was measured. It was found that carbon paper as supporter shows higher CO 2 capacity and desorption rate. A comparison of three different kinetic models shows that carbon paper as supporter gives a more enhanced kinetic behavior. Avrami's fractional order model presents the best fit to experimental data. To further investigate the mechanism of CO 2 uptake on absorbents, interparticle diffusion model, intraparticle diffusion model and Boyd's film diffusion model were also applied. Film diffusion resistance governed the mass transfer rate of CO 2 uptake on studied absorbents at the initial CO 2 uptake stages. In the following stages, intra-particle diffusion resistance plays a major role until the equilibrium is reached. The sensible heat of carbon paper as supporter is about 25% lower than that of poly tetra fluoroethylene as supporter. The desorption activation energy obtained from the Arrhenius equation is 18 kJ/mol for carbon paper as supporter, which is 84% lower than that of the typical aqueous MEA solvent. [ABSTRACT FROM AUTHOR]

[Display omitted] Thermal camouflage technologies, which aim at blending the infrared (IR) signature of targets into the background to counter the IR detection, have witnessed increasing development. To achieve thermal camouflage, the rule of thumb is to balance the thermal radiation between the target and the background, and the corresponding conductive strategy is to tune the local temperature field while the radiative strategy is to tune the local emissivity. Following these two basic strategies, the thermal metamaterials and wavelength-selective emissivity engineering to achieve thermal camouflage are first introduced. Then the more advanced dynamic strategies are reviewed that can adapt to the varying environment under the external stimuli, like electricity, light, strain, chemical, wetting, temperature, etc. Particularly the phase-changing and bioinspired materials are presented and reviewed. Finally, critical considerations on the challenges and opportunities of next-generation thermal camouflage technologies are elaborated and four future directions are cast, including temperature-responsive emissivity engineering, soft materials, multispectral camouflage, and detection-feedback system. Overall, a detailed introduction to the working principle, the state-of-the-art progress, and the critical thinking on the future development on thermal camouflage technologies are presented. [ABSTRACT FROM AUTHOR]

We synthesized polycyclosiloxanes with varying catechol substitution ratios (CFPSs) and investigated silver nanoparticles (AgNPs) adsorption ability on their self-assembled nanofilm. The nanoparticle adsorption ability as a function of the catechol substitution ratio was examined using SEM and a tape peeling test. It was evidenced that the substitution ratio of the catechol units was directly proportional to the surface density of AgNPs adsorbed on CFPS nanofilms. [ABSTRACT FROM AUTHOR]

To improve the corrosion resistance of 6061 Al in electric vehicle battery packs, a composite coating of nano-SiO2/Micro-Arc oxidation (MAO) ceramic structure was prepared on its surface. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves (PDP) were used to evaluate the corrosion resistance of the specimens after 7 days immersion in a 3.5% NaCl solution. The corrosion resistance of the prefabricated coatings was measured via local electrochemical impedance spectroscopy (LEIS). Confocal microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to characterize the microstructure and phase composition of the specimens. An energy dispersive spectrometer (EDS) was used to detect the elemental composition of the surface of the specimen. The results showed that the specimen with nano-SiO2/MAO composite coating had the least amount of micropores and superior corrosion resistance. The global electrochemical impedance of nano-SiO2/MAO composite coating was 1.1 times higher than that of the MAO coating and 8.4 times higher than that of the 6061 Al. When the coating was defective, the local electrochemical impedance of the nano-SiO2/MAO composite coating was still two times higher than that of the MAO coating. In the presence of scratches, the nano-SiO2/MAO composite coating still showed high corrosion resistance. The collapse corrosion mechanism of the nano-SiO2/MAO composite coating was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • 15 cm circular BiOI/In 2 O 3 thin film is grown by a gas–liquid interfacial process. • The grown film transferred on tape assembles a lightweight and twistable assembly. • The assembly can preserve its most photocatalytic activity after 10,000 times twist. • Integrating functional substrate with the assembly can deliver multi-functionalities. Mimicking the movement of leaves in response to external stimulations is inspiring for designing photocatalyst system applicable in space- and weight-sensitive scenarios. Here, we demonstrate that by combining a novel gas–liquid film growth process with a tape assisted film transfer procedure driven by capillary force, a lightweight and twistable photocatalyst assembly can be easily constructed. Taking the gas–liquid interface as a solute transfer boundary to selectively trigger the film growth at the interface, BiOI and BiOI/In 2 O 3 thin films up to 15 cm in diameter can be grown at a solution surface. Thanks to the capillary force present at the dynamic contact front during the film pick-up procedure, the grown film can be peeled off from the solution surface with tape so that a lightweight BiOI/In 2 O 3 /tape assembly can be easily constructed. Due to its low density and the BiOI/In 2 O 3 heterojunction formed, the resulting BiOI/In 2 O 3 /tape assembly exhibits superior photocatalytic activity per gram towards NO removal. Furthermore, the capillary force driven film pick-up process also induces a tight contact between the film and the tape, which makes the assembly highly twistable: its structural integrity and photocatalytic activity are largely preserved after 10,000 twists. Utilizing the film's flexibility and twistability, we assemble a temperature-, auto-folding/unfolding photocatalyst system by transferring the film onto a memory-alloy-based structure, which mimics the movement of leaves in response to external stimulations and makes the gas–liquid interface-derived BiOI/In 2 O 3 /tape assembly suitable for use in space- and weight-limited environments. [ABSTRACT FROM AUTHOR]

Dimethyl carbonate (DMC) was synthesized from methanol and ethylene carbonate (EC) in a reactive distillation column by transesterification using different composite oxide catalysts. The catalysts were characterized by XRD, N2 adsorption‐ desorption, CO2‐TPD, and NH3‐TPD. The results show that the Zr−Al catalyst has the most strong base sites and weak acid sites compared with other catalysts. The synergistic effect of acid‐base sites makes it show excellent catalytic performance for DMC synthesis. The operation parameters including reflux ratio, feed molar ratio, liquid hourly space velocity (LHSV) and catalyst dosage were optimized by factorial design based on response surface methodology (RSM). The best optimization conditions was: reflux ratio=5.23 : 1, feed molar ratio=6.05 : 1, LHSV=0.48 h−1, catalyst dosage=119.04 ml, the relative error between measured value and predicted value is small, which indicated that the reliability of the optimized process is high. [ABSTRACT FROM AUTHOR]

Walking on different terrains leads to different biomechanics, which motivates the development of exoskeletons for assisting on walking according to the type of a terrain. The design of a lightweight soft exoskeleton that simultaneously assists multiple joints in the lower limb is presented in this paper. It is used to assist both hip and knee joints in a single system, the assistance force is directly applied to the hip joint flexion and the knee joint extension, while indirectly to the hip extension also. Based on the biological torque of human walking at three different slopes, a novel strategy is developed to improve the performance of assistance. A parameter optimal iterative learning control (POILC) method is introduced to reduce the error generated due to the difference between the wearing position and the biological features of the different wearers. In order to obtain the metabolic rate, three subjects walked on a treadmill, for 10 min on each terrain, at a speed of 4 km/h under both conditions of wearing and not wearing the soft exoskeleton. Results showed that the metabolic rate was decreased with the increasing slope of the terrain. The reductions in the net metabolic rate in the experiments on the downhill, flat ground, and uphill were, respectively, 9.86 % , 12.48 % , and 22.08 % compared to the condition of not wearing the soft exoskeleton, where their corresponding absolute values were 0.28 W/kg, 0.72 W/kg, and 1.60 W/kg. [ABSTRACT FROM AUTHOR]

With the rapid development of microelectronic technology, increasing wearable devices are available for us in daily lives. These wearable devices are usually powered by batteries, so the endurance of wearable devices is limited by battery capacity. Biomechanical energy harvesting (EH) is a promising approach to extend the endurance or replace batteries to power microelectronic devices. In this paper, we would first review the different types of EH devices and analyze the key technologies. Secondly, to compare the advantages and disadvantages of different EH devices, the design guidelines of the EH device is proposed. According to the design guidelines, an EH device with a weight of only 110 g is designed, which is lighter than the suspended-load backpack (38 kg) and the knee harvester (1.6 kg). Our EH device is able to convert the vibrations energy generated by the motion of lower limbs into electrical energy. Finally, to verify whether our EH device meets the design guidelines, three sets of experiment are conducted to evaluate the performance of the EH device. Experiment A is used to monitor the metabolic energy and electricity energy. According to experiment data, we calculate the COH and TCOH of EH device. The lowest COH and TCOH are 58 and 59, respectively. The TCOH of our EH device is higher than suspended-load backpack (30.7) and the knee harvester (13.6). Experiment B is used to test the adaptability of the EH device under the different conditions of terrains and walking speeds. The EH device is able to harvest energy in different terrains (up and down stair, at the treadmill with a slope of 0 ° , 5 ° and 10 ° ) and at different speeds(4 km/h~8 km/h). The converted electrical power is up to 7.71 mW during walking at the speed of 8 km/h and is up to 5.28 mW when going up stairs. Experiment C is conducted to investigate the influence of the EH device on human motion by measuring the torque of the ankle, knee, and hip joints. When comparing the curves of torque, the EH device does not influence the biological moment of joints, indicating the EH device does not interfere with the movement. At the same time, another method to calculate the TCOH by calculating the net work done by the muscle in a gait cycle is proposed. When comparing the TCOH calculated by the metabolic energy with the TCOH calculated by the additional work done by the muscle, the results are basically the same. Meanwhile, the variation of the latter calculation result is smaller, indicating the method proposed by us is more precise. [ABSTRACT FROM AUTHOR]