Search

High-performance stretchable strain sensors are highly desirable for various scenarios, such as health monitoring and human-robot interfaces. Here, we propose a universal strain engineering strategy that introduces an inhomogeneous spatial distribution of stress and promotes crack propagation behavior leading to a critical state between network and channel morphologies, achieving stretchable strain sensors with high sensitivity, a wide working range and good linearity. Approaches for introducing soft-rigid interfaces, enlarging elastic modulus mismatches and matching dimensions have been employed to execute the strategy for network-crack strain sensors with collapsed nanocone cluster structures as representatives. The strain sensors can be tuned to realize a gauge factor of 690.95 in a linear working range of 0–40% (R 2 = 0.993) or a gauge factor of 113.70 in a larger linear working range of 0–120% (R 2 = 0.999). Intraocular pressure monitoring and dynamic facial asymmetry assessment have been demonstrated based on these sensors to show their great application potential. [Display omitted] • A critical state between network and channel morphologies was achieved for crack-based sensors via strain engineering. • Sensitivity, stretchability, and linearity are co-optimized in strain sensors. • A GF of 690.95 in a linear working range of 0–40% can be realized with adjustability. • The highest sensitivity for intraocular pressure monitoring was achieved. • Dynamic facial asymmetry assessment was demonstrated for the first time. [ABSTRACT FROM AUTHOR]

Sign language recognition is of great significance to connect the hearing/speech impaired and non-sign language communities. Compared to isolated word recognition, sentence recognition is more practical in real-world scenarios, but is also more complicated because continuous, high-quality sign data with distinct features must be collected and isolated signs must be identified with high accuracy. Here, we propose a wearable sign language recognition system enabled by a convolutional neural network (CNN) that integrates stretchable strain sensors and inertial measurement units attached to the body to perceive hand postures and movement trajectories. Forty-eight Chinese sign language words commonly used in daily life were collected and used to train the CNN model, and an isolated sign language word recognition accuracy of 95.85% was achieved. For sentence-level sign language recognition, we proposed a method that combines multiple sliding windows and uses correlation analysis to improve the CNN recognition performance, achieving a correct rate of 84% for 50 sign language sentence samples, showing good extendibility. [Display omitted] • A wearable system that attached to the body to perceive hand postures and movement trajectories was demonstrated. • A high accuracy of 95.85% was achieved in isolated sign language word recognition for Chinese sign language. • Combining multiple sliding windows and correlation analysis, a correct rate of 84% for sign language sentence was achieved. [ABSTRACT FROM AUTHOR]

To compare the effect of audio-guided mental practice (MP) and video-guided MP on impairment and functional abilities of upper extremity (UE) hemiparesis following stroke. Randomized controlled trial. Participants were randomly assigned: audio-guided MP, video-guided MP, repetitive task practice (RTP), or traditional therapy (control) groups. Baseline and post-intervention scores from outcome measures were compared. Inpatient Rehabilitation Hospital. Inclusion Criteria: ages 18-80, less than one month post stroke, moderate UE hemiparesis. Exclusion: history of prior stroke, severe pain, comorbidities, spasticity, aphasia or cognitive impairments, inability to perform MP, non-english speaking.18 participants completed the study, two participants were eligible and refused. MP groups performed MP five days a week (via video or audio guidance), of the following tasks: wiping a table, picking up a cup, brushing hair, and turning the pages of a book. The RTP group physically performed the same tasks. The control group received traditional stroke rehabilitation. Wolf Motor Function Test (WMFT) and Fugl Meyer Assessment- Upper Extremity (FM). Wilcoxon signed-rank test demonstrated that audio MP increased FM scores from pre-test (Mdn = 34.0, Mean = 34.0, SD =9.56) to post-test (Mdn = 49.0, Mean = 49.6, SD =7.5), n= 5, Z= 2.03, p=.042, r=.91). Similar improvement in FM scores was found with traditional therapy. Audio MP also decreased WMFT time, pre-test (Mdn = 10.5, Mean = 49.9, SD= 59.1) to post-test (Mdn = 4.1, Mean 3.5, SD = 1.4), Z=2.02, p=.043, r=.90. Audio MP and traditional therapy appear to decrease impairment and increase the functional abilities of the UE following stroke. Video MP and RTP did not have this effect. These preliminary findings expand therapeutic options to existing occupational therapy practice in stroke rehabilitation. No conflict of interest. [ABSTRACT FROM AUTHOR]

Synthetic phenolic antioxidants (SPAs) are widely used as food additives to delay the oxidation rate of oils and oil products. The concentrations and compositions of SPAs in Chinese residents' most popular daily foods and the resulting exposure risk of SPAs are not clear. Therefore, this study collected food samples in 13 food categories (n = 289) from 10 provinces in China. At least one of the SPAs was detected in approximately 99.7% of foodstuffs, and the concentration of ∑SPAs ranged from not detected to 7830 (geometric mean (GM): 296 ng/g wet weight). 2,6-2 tert butyl p-1,4-benzoquinone (BHT-Q) was the main transformation product, but SPAs in food tend to exist in the parent form. A significant difference between food categories was analyzed. The highest GM of ΣSPAs occurred in cereals and cereal products, which was approximately 8 times higher than that in beverages. The estimated daily intakes of ΣSPAs in Chinese preschoolers, school-age children, adults and elderly individuals were 22200, 9970, 7540 and 7700 ng/kg bw/day, respectively. The exposure risks of SPAs decreased with age. This is the first simultaneous analysis of SPAs in multiple provinces and multiple categories of foodstuffs. [Display omitted] • SPAs were measured in 289 food samples in 13 categories from 10 provinces in China. • The concentrations of ∑ 9 SPAs in foods were of n.d.-7830 ng/g wet weight. • The highest GM concentrations of ∑ 9 SPAs were found in cereals and cereal products. • The preschoolers are at the highest risk of exposure to SPAs through food intake. • The first simultaneous analysis of SPAs in multiprovince and multicategory of foods in China. [ABSTRACT FROM AUTHOR]

Abstract: We show that a class of regular self-adjoint fourth order boundary value problems (BVPs) is equivalent to a certain class of matrix problems. Conversely, for any given matrix problem in this class, there exist fourth order self-adjoint BVPs which are equivalent to the given matrix problem. Equivalent here means that they have exactly the same eigenvalues. Such an equivalence is considered with the special coupled boundary conditions, i.e. periodic boundary conditions. [Copyright &y& Elsevier]

Abstract: In this paper, we consider the dependence of eigenvalues of a class of fourth-order Sturm–Liouville problems on the boundary. We show that the eigenvalues depend not only continuously but smoothly on boundary points, and that the derivative of the nth eigenvalue as a function of an endpoint satisfies a first order differential equation. In addition, we prove that as the length of the interval shrinks to zero all higher fourth-order Dirichlet eigenvalues march off to plus infinity, this is also true for the first (i.e., lowest) eigenvalue. [Copyright &y& Elsevier]

Abstract: The eigenvalues of a regular fourth-order Sturm–Liouville (SL) problems depend not only continuously but smoothly on the problem. An expression for the derivative of the eigenvalues with respect to a given parameter: an endpoint, a boundary condition, a coefficient, or the weight function, are found. [Copyright &y& Elsevier]

Spatiotemporal recognition of multiple mechanical stimuli is essential for electronic skin (e-skin), which can provide more complete and accurate interaction information to enable elaborated functions, such as gesture recognition, object manipulation, and fine tactile discrimination. However, nonspecific sensor response and performance sacrifice for integration limit the perceptual capability of the current systems. Here, we report a bioinspired e-skin that can measure strain, shear and pressure independently with direction information using three-dimensional integrated, mechanically isolated multiple sensors. Novel microstructures of collapsed nanocone clusters, hemi-ellipsoids, and wrinkles are introduced in different sensors to achieve a gauge factor of 6 with a linear working range of 80% (linearity > 0.99) for strain, a sensitivity of 0.1 N−1 for shear force, and a sensitivity of 3.78 kPa−1 for pressure, and all of these sensors possess short response times on the order of 100 ms. The independent, highly sensitive, and fast response of these sensors makes real-time recording and mapping of multiple mechanical stimuli to be achieved. Multi-touch gesture recognition and perception of a red bean (0.065 g) in the hand are demonstrated to illustrate the potential applications in wearables, robotics and bionic prostheses. A bioinspired e-skin that discriminates strain, shear and pressure is developed through a three-dimensional mechanical design cooperated with sophisticated microstructures. Isolated responses of different sensors that possessing excellent performance enabled spatiotemporal recognition of multiple mechanical stimuli toward advanced wearable clinical/biological technologies. [Display omitted] • Collapsed nanocone clusters are newly developed to maintain high electrical conductivity of the coated metal film even stretched up to 95% strain. • Simultaneously -identifying strain, shear and pressure with direction information was realized for the first time. • Spatiotemporal recognition of multiple mechanical stimuli was demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we discuss the maximal number of limit cycles which appear under perturbations in Hopf bifurcations by using degenerate first-order Melnikov function with multiple parameters. [Copyright &y& Elsevier]

• Ginger extract was innovatively used as a corrosion inhibitor for reinforced concrete. • QM/MD methods were used to simulate the adsorption processes of inhibition molecules. • The passive films for systems with/without ginger extract were analyzed by XPS. • Three possible adsorption mechanisms for ginger corrosion inhibitors were proposed. In our recent work, the inhibition effect of ginger extract was preliminarily studied in simulated concrete pore solutions. Now it was applied in cementitious materials to augment the reinforcement corrosion resistance. The inhibition effects of ginger extract and three other commonly used corrosion inhibitors were studied and compared by means of open circuit potential, linear polarization resistance and electrochemical impedance spectroscopy. X-ray photoelectron spectroscopy was used to analyze the chemical compositions of the film formed on the steel bar embedded in the cement mortars. For further understanding the insight of inhibition mechanisms, molecular dynamics and quantum mechanics methods were used to simulate the adsorption processes of the major inhibition molecules onto the surface of steel reinforcement. In addition, the effects of the ginger extract on the flowability and strength of fresh and hardened cement mortars were also examined. The results showed that the ginger extract acting as an effective corrosion inhibitor can lower the corrosion risk of steel bars embedded in cement mortars. The ginger extract's effective corrosion inhibition was mainly attributed to the formation of a carbonaceous organic film on the steel surface. According to the experimental and simulation results, three potential mechanisms of adsorption were proposed. Plus, it was found that the addition of the ginger corrosion inhibitor in cement mortars had a positive effect on the flowability and a negligible negative effect on the strength. The overall findings demonstrated that this ginger extract holds great potential for broader applications in practical engineering. [ABSTRACT FROM AUTHOR]

Abstract. In this study, we tried to employ the ginger extract as an environmentally friendly inhibitor to improve chloride-induced corrosion resistance of reinforcing steel in simulated concrete pore solutions. The inhibiting performances of ginger extract as well as three other inhibiting systems were studied by stereo-microscope and various electrochemical measures. The main phenolic compounds of ginger extract were confirmed by liquid chromatography-mass spectrometry. Meanwhile, the elements and chemical bonds existed in the surface passive film of the steel bar immersed in the ginger inhibiting system were characterized via attenuated total reflection Fourier transform infrared spectroscope (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Electrochemical results indicated that the ginger extract was an efficient corrosion inhibitor in reducing the chloride-induced corrosion and at the optimal dosage (2%) it could improve the chloride threshold values of steel electrodes from 0.02 mol/L to 0.08 mol/L. From the results of potentiodynamic polarization, ATR-FTIR and XPS, it was found that the ginger extract was a mixed type corrosion inhibitor that improved the corrosion resistant performance of carbon steel mainly by forming a carbonaceous organic film to restrain both the cathodic and the anodic corrosion reaction. Highlights • We innovatively employed ginger extract as an environmentally friendly inhibitor in SCP solutions. • Ginger extract has been confirmed as an effective mixed-type corrosion inhibitor by various electrochemical measures. • Results from ATR-FTIR and XPS confirmed the formation of the carbonaceous organic film on the steel bar. [ABSTRACT FROM AUTHOR]

• Online disinhibition positively associated with cyberbullying activities. • Online disinhibition functioned through moral disengagement and low self-control to influence cyberbullying. • Most studies focused on the effects of anonymity on cyberbullying, and the results were inconsistent. • Online invisibility had no effect on cyberbullying. • Asynchrony influenced cyberbullying directly and indirectly through moral disengagement. There has been a growing focus on researching adolescent cyberbullying in recent years. Increasing studies highlight the role of online risk factors—online disinhibition and its specific characteristics—in cyberbullying among adolescents. Systematic searches were performed in MEDLINE, PubMed, PsycArticles, PsycINFO, Scopus, and Web of Science. There were 837 papers in total, 410 of which were non-duplicated, and 15 were ultimately included. Based on the current empirical findings, it has been observed that a heightened perception of online disinhibition corresponds with an increased likelihood of engaging in cyberbullying activities. In addition to the direct effect of online disinhibition on cyberbullying, research also found that online disinhibition functioned through moral disengagement and low self-control to influence cyberbullying. Furthermore, the effects of specific characteristics of online disinhibition on cyberbullying were also investigated. However, most studies (six out of seven) merely focused on the effects of anonymity on cyberbullying, and the results were inconsistent. Additionally, the effects of perception of invisibility and asynchrony on cyberbullying were also examined in limited research. The results showed that online invisibility had no effect on cyberbullying. Asynchrony contributed to cyberbullying directly and indirectly through moral disengagement. Further research is required to investigate the impacts of solipsistic introjection, dissociative imagination, and minimizing authority on the occurrence of cyberbullying. These findings are discussed, and practical as well as policy implications and guidelines for future studies are proposed. [ABSTRACT FROM AUTHOR]

Highlights • Electrochemical impedance spectroscopy is applied to evaluate the leaching behavior. • A new electrical equivalent circuit is proposed to extract parameters from impedance spectra. • A linear relationship between x L and R′ CCP is suggested to quantify the leaching depth. Abstract This study employed EIS (electrochemical impedance spectroscopy) as a non-destructive method to study the leaching behavior of the cementitious materials subjected to aggressive environments. A novel electrical equivalent circuit was established based on a microstructure assumption concerning the leaching-induced degradation. Electrochemical parameters were extracted from the impedance spectra by fitting the established equivalent circuit. On the basis of the understanding of the physical meanings, a proper equivalent-circuit parameter was defined as the indicator of leaching depth. Then the relationship between the leaching depth and the indicator was estimated. As a result, leaching depths can be quantitatively estimated using EIS method. [ABSTRACT FROM AUTHOR]

Highlights: [•] Bisphenol A and genistein were classified as weakly and strongly embryotoxic respectively in embryonic stem cell test. [•] The combined exposure effects of BPA and GEN were evaluated using a 4×4 full factorial design. [•] BPA and GEN have a synergistic effect on embryonic stem cells differentiation at lower dosages. [ABSTRACT FROM AUTHOR]

• A novel green corrosion inhibitor was prepared from the waste PAL. • The PAL extract was conformed as an efficient mixed type corrosion inhibitor. • QM/MD simulations based on UPLC-MS supported the donor–acceptor adsorption and inhibition mechanism for PAL extract. • XPS provided the formation evidence of the carbonaceous/nitrogenous film on steel surface. In this study, an environmentally friendly corrosion inhibitor was prepared from waste Platanus acerifolia leaves (PAL) for reducing the chloride-induced reinforcement corrosion. Four extraction methods were employed in the preparation work. The inhibiting performances of the four types of PAL extracts and two benchmark inhibitors were studied by various electrochemical measures. After that, the optimal group was obtained (extract #4, prepared by an ultrasonic-assisted alkali-pretreated ethyl extraction method) and analyzed with ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) to determine its main chemical constituents. The inhibition/adsorption mechanism was analyzed via X-ray photoelectron spectroscopy (XPS) as well as the quantum mechanics and molecular dynamics simulations. According to the results of electrochemical experiments, the PAL extract is an excellent mixed type inhibitor that restrains both the cathodic and anodic reactions. UPLC-MS results provided the existence evidence of more than ten kinds of flavonoids or oligopeptides in the PAL extract. XPS and simulation results indicated that these flavonoids/oligopeptides exerted their inhibition effect by generating a nitrogen-carbon film on the steel substrate via the donor–acceptor interactions of reactive sites. [ABSTRACT FROM AUTHOR]