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Glucose, a widely distributed biomaterial in nature, is presented as a new cathode interfacial material for highly efficient inverted organic solar cells. The interactions between glucose and the indium tin oxide (ITO) substrate as well as the formation mechanisms of the glucose interlayer were investigated by molecular dynamics simulation and relevant experimental tests. The results revealed that the In-OH coordination between the oxygen atom of glucose and the indium of ITO is the key factor for the formation of interfacial dipoles, thereby reducing the work function of the ITO cathode for efficient charge transfer. With PM6:Y6 as the active layer, the power conversion efficiency (PCE) of the organic solar cells was significantly increased from 1.99 to 15.42% after ITO was modified by a glucose interlayer through the traditional spin-coating method. More importantly, glucose can be adsorbed on the ITO surface by a simple immersion process, and the devices based on the modified ITO by immersed glucose achieved a PCE of 14.48%, which is comparable to that of the traditional spin-coating method. Furthermore, we found that the OSCs with the ITO cathodes modified with glucose derivatives including sorbitol and sodium gluconate by different preparation methods also exhibited high performance. The overall performance of the devices with ITO modified by a simple and low-cost immersion method can be maintained at more than 93% of that prepared with the traditional spin-coating method. The results demonstrated that low-price glucose and its derivatives are good candidates as ITO interlayer materials for OSCs, and the effectiveness of the immersion process paves a way for simplifying the manufacture of low-cost and large-area organic solar cells.

Organic memristors are considered to be the next-generation storage element due to their unique advantages of flexibility, transparency, and good solution processability. In this Letter, a Zn-porphyrin based small-molecular organic memristor is prepared by spin-coating with an ultralow resistive switching set voltage of 0.38 V. It is found that the zinc atom in the porphyrin molecule plays a very important role in improving the resistance switching characteristics of organic memristors. By tracking the change in oxygen valence in the vertical dimension, we demonstrate that Zn atom located in the core of porphyrin helps to enhance the oxygen ion migration across the active layer, clearly revealing the memory mechanism of low-cost solution-processed Zn-porphyrin based small-molecular organic memristors. This organic memristor shows excellent memristive performance resulting from rational material design and appropriate device structure engineering.

Browning of white adipose tissue (WAT) is becoming an attractive therapeutic target for obesity. Great efforts have been made to develop effective approaches to induce browning. Unfortunately, the current methods suffer from a series of disadvantages, such as low efficiency, unsatisfactory stability, and side effects. Herein, we report a new approach to induce browning of 3T3-L1 white adipocytes based on electromagnetic induction heating (EIH) hyperthermia. In particular, adipocyte-targeting aptamer modified gold nanoclusters (Apt-AuNCs) were employed as the mediators of EIH. Apt-AuNCs had good biocompatibility and excellent targeting performance with white adipocytes. After Apt-AuNCs/EIH treatment, adipocytes with characteristic multilocular and small lipid droplets increased, and the content of triglycerides reduced effectively. Apt-AuNCs/EIH treatment also significantly increased the mitochondrial activity in adipocytes. Meanwhile, the mRNA levels of key genes that are involved in browning, for example UCP1, PRDM16, PPARγ, and PGC-1α, were upregulated. Finally, the induction mechanism of Apt-AuNCs/EIH on browning of white adipocytes was explained by the synergistic effects of EIH hyperthermia and pharmacological action of AuNCs. To the best of our knowledge, this is the first attempt on induction of browning by metal nanocluster-mediated EIH hyperthermia, thus providing an interesting and efficient channel for obesity treatment.

Aptamer-functionalized AuNCs nanogel as the targeted delivery vehicle of docosahexaenoic acid to induce browning of white adipocytes.

Object in-hand reorientation is widely known to be crucial for robotic dexterous manipulation, and the stable reorientation of the in-hand object with the two-fingered gripper is challenging. In this paper, the object reorientation is completed using a commercial two-fingered gripper with integrated force/torque sensors. The identification models for the object in-hand status (slipping status and pivoting status) are built based on the friction theory. In-hand status identification provides an important guarantee for the object in-hand reorientation. Moreover, we propose a control framework for the object in-hand reorientation under the action of gravity. This framework is to make the object slip or pivot by continuously controlling the gripping force. The force control law is related to the object’s kinematics parameters, and the gripping force is modified according to the object in-hand status and kinematics parameters. Finally, the effectiveness of the proposed method is validated by testing object slipping and object pivoting in experiments. Results show that the gripping point and pose of the in-hand object are adjusted through object slipping and object pivoting.

Fast pyrolysis has been recognized as an efficient and feasible way to produce liquid fuels from biomass. For the aim to upgrade the products from fast pyrolysis of hemicellulose, reduced graphene oxide supported Pt nanoparticles (Pt/RGO) was adopted as catalyst for in situ catalytic fast pyrolysis (CFP). Pt/RGO was prepared by one-step thermal reduction method, and further employed as catalyst for in situ CFP of xylan. Online single-photon ionization time-of-flight mass spectrometry was employed to detect the volatile products, and furans were chosen as the model compounds. The experimental results showed that Pt/RGO distinctly increased the intensity of furans products from xylan pyrolysis, as the increase rates were respectively 80.5%, 64.4% and 50.2% in 400 °C, 500 °C and 600 °C. Furthermore, Pt/RGO can accelerate the process of xylan pyrolysis and be effective in eliminating oxygen for furans products. With addition of Pt/RGO, O/C ratio for furans products decreased from 0.38 to 0.32 in 400 °C, 0.37 to 0.32 in 500 °C, and 0.35 to 0.32 in 600 °C, respectively. This work proved that Pt/RGO had the potential to be a highly efficient catalyst for upgrading of the volatile products from in situ CFP of biomass.

Here, high performance polymers bearing photo-crosslinkable function are developed for all-PSCs to achieve both high efficiency and stability. Then, a series of novel -(D-A)a-(D-D1)b-type photo-crosslinkable bromine (Br)-functionalized polymer donors PBDT(T)FTAZ-BX were synthesized, in which typical benzodithiophene (BDT) derivative was as first component (D), thiophene-difluro-benzotriazole (FTAZ) derivative was as second component (A), new simple BDT-based functionality appended Br-unit synthesized in this study was as third component (D1). The effects of Br-functionalized component on the photoelectric properties of the polymers were investigated. Moreover, UV-mediated photo-crosslinking effects on performance and thermal stability were thoroughly explored. All-PSCs based on these photo-crosslinkable polymers and N2200, but without photo-crosslinking, displayed a highest PCE of 7.21%, which was achieved by an optimized PBDT(T)FTAZ-B5-based device. As results, photo-crosslinked PBDT(T)FTAZ-B5 + UV5min-based devices afford extraordinarily excellent thermal stability, in which high retention rate of 91.8% of the maximum PCEavg and the intrinsic performance (PCEmax: 6.12%) are maintained even after 72 h 150 °C annealing. For comparison, reference PBDT(T)FTAZ-based devices only display PCEmax value of 5.13% and retain 84.2% of their maximum PCEavg under same aging. This contrasting result indicates that developing photo-crosslinkable Br-functionalized polymers is an effective strategy to further advance in both stability and efficiency of all-PSCs.

We propose a nonlinear acoustic metasurface concept by exploiting the nonlinearity of locally resonant unit cells formed by curved beams. The analytical model is established to explore the nonlinear phenomenon, specifically the second-harmonic generation (SHG) of the nonlinear unit cell, and validated through numerical and experimental studies. By tailoring the phase gradient of the unit cells, nonlinear acoustic metasurfaces are developed to demultiplex different frequency components and achieve anomalous wavefront control of SHG in the transmitted region. To this end, we numerically demonstrate wave steering, wave focusing, and self-bending propagation. Our results show that the proposed nonlinear metasurface provides an effective and efficient platform to achieve significant SHG and separate different harmonic components for wavefront control of individual harmonics. Overall, this study offers an outlook to harness nonlinear effects for acoustic wavefront tailoring and develops potential toward advanced technologies to manipulate acoustic waves.

This paper investigates the vibration and sound radiation of porous functionally graded material (FGM) plates with temperature gradient along the thickness. The even and uneven porosity distributions are taken into consideration in the present study. The formulation of the FGM plate is based on the first-order shear deformation theory (FSDT) with the temperature dependence of material properties considered. Each displacement component of the FGM plate is expanded as the Fourier cosine series combined with auxiliary functions in order to satisfy the general boundary conditions. A substantial number of numerical examples concerning the vibration and sound radiation responses of the heated plate are carried out to validate the convergence and accuracy of the proposed method. Finally, the effects of key parameters including the boundary condition, volume fraction index, thermal environment, temperature dependence of material properties and porosity volume fraction on the structural and acoustic responses of the FGM plate are discussed in detail.

Benzyl butyl phthalate (BBP) is a widely used plasticizer and has raised public health concerns. Here, we report the effects of BBP on the testis development during rat puberty. BBP (0, 10, 100 or 1000 mg/kg) was gavaged to 35-day-old male Sprague Dawley rats for 21 days. The serum testosterone levels, Leydig cell number, the expressions of Leydig and Sertoli cell genes and proteins were measured. The in vitro effects on steroidogenesis and gene expression in immature Leydig cells were observed. BBP significantly increased serum testosterone level at 10 mg/kg but lowered its level at 1000 mg/kg without affecting serum luteinizing hormone and follicle-stimulating hormone levels. BBP increased Leydig cell number at all doses but inhibited steroidogenic capacity per Leydig cell at 1000 mg/kg. BBP significantly increased the ratio of phosphos-AKT2 (pAKT2)/AKT2, and phosphos-ERK1/2 (pERK1/2)/ERK1/2 in the testis. Mono-benzyl phthalate (the metabolite of BBP) inhibited steroidogenesis but BBP did not affect androgen production in immature Leydig cells in vitro. In conclusion, BBP non-linearly regulates Leydig cell development by increasing Leydig cell number but inhibiting steroidogenesis.

Luminescent metal nanoclusters (NCs) have recently emerged as a novel class of luminescent nanomaterials and hold significant potential in biomedicine owing to their ultrasmall (< 2 nm) size, excellent photostability, and good biocompatibility. The recent rapid advances in the synthesis and functionalization of luminescent metal NCs have enabled scientists to develop colorful nanomaterials and nanodevices for a wide range of biomedical applications. In this review, we summarize the characteristics and advantages of luminescence from metal NCs, and highlight their applications in biomedicine. We focus on the research in biomedical detection, bio-imaging, drug delivery, and therapy, especially for the advances in the last five years. Luminescent metal NCs display a series of unique superiorities in biomedical applications, and the recent achievements have brought a lot of benefits to the diagnosis and treatment of clinical diseases, especially for tumors and cancers. Finally, we put forward the main challenges that currently still hinder the basic science studies and the practical development of luminescent metal NCs in biomedical applications. Overall, we expect that luminescent metal NCs will play a much more important role in future biomedicine and clinical applications.

Controlling elastic/acoustic wave-front via compact designs has attracted increasing research interest in past decades. The emerging of metasurface concept provides an unconventional and attractive approach in this filed. A metasurface generally consists of a single array of subwavelength-scaled patterns in the host medium, introducing an abrupt phase shift in the wave propagation path. In this paper, we explored an elastic metasurface concept to control the propagation of low-frequency flexural Lamb waves. The phase modulation based on the Snell’s law was achieved by tailoring the thickness of thin beam resonators connecting two elastic host medium. Depending on the design of the phase-modulated structure (a.k.a. metasurface), elastic waves could be steered or focused which was verified through analytical and numerical models.

Stability and energy efficiency are the main focuses in the bipedal robot field. In this paper, we apply a multiphase gait, which is different from the widely used two-phase gait, to improve the stability at the moment, when a biped robot transfers from the double support phase to the single support phase. Then, we create dynamic equations with contact forces in each phase using Lagrangian formulation. Furthermore, the direct collocation method is utilized to generate the optimal trajectory toward both stability and energy efficiency. Finally, the comparison between multiphase gait and two-phase gait is performed with numerical simulations. The results prove that multiphase gait increases the stability margin in the cost of slightly decreasing energy efficiency. Besides, both gaits show a similar human-like characteristic in hip height variation during walking.

Network embedding has recently emerged as a promising technique to embed nodes of a network into low-dimensional vectors. While fairly successful, most existing works focus on the embedding techniques for static networks. But in practice, there are many networks that are evolving over time and hence are dynamic, e.g., the social networks. To address this issue, a high-order spatio-temporal embedding model is developed to track the evolutions of dynamic networks. Specifically, an activeness-aware neighborhood embedding method is first proposed to extract the high-order neighborhood information at each given timestamp. Then, an embedding prediction framework is further developed to capture the temporal correlations, in which the attention mechanism is employed instead of recurrent neural networks (RNNs) for its efficiency in computing and flexibility in modeling. Extensive experiments are conducted on four real-world datasets from three different areas. It is shown that the proposed method outperforms all the baselines by a substantial margin for the tasks of dynamic link prediction and node classification, which demonstrates the effectiveness of the proposed methods on tracking the evolutions of dynamic networks., Accepted by COLING 2020 : The 28th International Conference on Computational Linguistics

Background Biped robot locomotion is an active topic of research, and the walking stability is one of the research objectives. Objective This paper discusses the variable stiffness ankle joint and the walking control of a biped robot. Methods A design is introduced that achieves the ankle joint variable stiffness by using a pneumatic unit. The actuation system of the biped robot is based on the hybrid use of electric and pneumatic. The locomotion control architecture has been proposed to exploit natural leg dynamics in order to improve the biped robot walking stability. We also present a dynamic simulation which matches the biped robot and experiments with the real biped robot. Results The simulation and experiments result that introducing the variable stiffness ankle joint and the controller achieve a significant improvement in foot-ground impact and walking stability of the biped robot. Conclusion The biped robot with variable stiffness ankle joints has a better walking performance under the control method.

Multiscale array (MSA) structures are present to reduce the front-side surface reflection loss of solar cells, which consists of nanostructure patterns spanned across the curved surface of micrometer-sized plano-concave cylindrical arrays. The MSAs are fabricated using flexible polydimethylsiloxane (PDMS) polymer by simple template replication together with surface modification technique and characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Optical characterization shows the MSA structure can reduce 3.85% integrated reflectivity of multicrystalline silicon solar cell encapsulated by the flat epoxy resin polymer (ERP) coating. Importantly, the MSA antireflective coating can improve the photovoltaic conversion efficiency of the ERP-encapsulated solar cell from 17.50% to 18.34% and can increase the contact angle of a 2 μL water droplet on the solar cell surface from 110.5° to 153.1°. These improvements have great significance for commercial Si solar cell devices.

One-monomer molecularly imprinted magnetic nanoparticles were prepared as adsorbents for selective extraction of bisphenol A from water in this study. A single bi-functional monomer was adopted for preparation of the molecularly imprinted polymer, avoiding the tedious trial-and-error optimizations as traditional strategy. Moreover, bisphenol F was used as the dummy template for bisphenol A to avoid the interference from residual template molecules. These nanoparticles showed not only large adsorption capacity and good selectivity to the bisphenol A but also outstanding magnetic response performance. Furthermore, they were successfully used as magnetic solid-phase extraction adsorbents of bisphenol A from various water samples, including tap water, river water, and seawater. The developed method was found to be much more efficient, convenient, and economical for selective extraction of bisphenol A compared with the traditional solid-phase extraction. Separation of these nanoparticles can be easily achieved with an external magnetic field, and the optimized adsorption time was only 15 min. The recoveries of bisphenol A in different water samples ranged from 85.38 to 93.75%, with relative standard deviation lower than 7.47%. These results showed that one-monomer molecularly imprinted magnetic nanoparticles had the potential to be popular adsorbents for selective extraction of pollutants from water.

A new type of magnetic nanoparticles (MNPs), as the absorbents of bisphenol A (BPA), was prepared by functionalization of Fe3O4@SiO2 with BPA-specific aptamer in this work. ssDNA aptamer was immobilized on the Fe3O4@SiO2 surface through biotin-avidin interactions, playing a role of the specific probe for BPA. The resultant materials (Apt-MNPs) exhibited outstanding magnetic responsibility and can be separated efficiently by the magnetic field. Experimental results also showed that Apt-MNPs had large adsorption capacity and high competitive selectivity for the targeted compound BPA. Furthermore, Apt-MNPs were adopted as the specific absorbents to extract and enrich BPA from human serum and urine samples. Therefore, an efficient detection method of BPA was developed in combination with high-performance liquid chromatography (HPLC). The linearity of the method was over a range of 5–10,000 ng mL−1 with a correlation coefficient of 0.99997, and the limit of detections (LODs) for serum and urine were 2.0 and 1.0 ng mL−1, respectively. The recoveries of BPA in the spiked human serum and urine samples were 90.8 ± 7.3% (RSD) and 92.3 ± 1.5%, respectively. Our results demonstrated that Apt-MNPs were high-performance adsorbents for extracting and enriching BPA, resulting in fast and efficient detection of BPA in serum and urine samples.

Aptamers have recently been widely employed as recognition elements for the discovery and detection of protein biomarkers. Therefore a comprehensive and in-depth understanding of the interaction between aptamers and their target proteins is especially important. Herein we report a real-time and label-free strategy to detect the interaction between alpha-fetoprotein (AFP), a specific biomarker of hepatocellular carcinoma, and its specific ssDNA aptamer based on dual polarization interferometry (DPI). The ssDNA aptamer was immobilized on the surface of a sensor chip followed by AFP injection, while the changes of mass, thickness and density on the AFP–aptamer interface were monitored and recorded online by DPI. The experimental results showed that there were two different interaction patterns between AFP and the aptamer, which were specific binding and unspecific binding, and the former was found to be the dominant one. AFP binding makes the conformation of the aptamer change, resulting in an increase of mass/thickness and a decrease of density. The concentration of AFP is very important for the AFP–aptamer interaction, as a high AFP concentration will lead to a high probability of the aptamer capturing AFP and therefore a large binding amount and a high mass loading rate. The developed detection method proved effective to study the interaction behavior and mechanism between AFP and its aptamer, and will find wide applications in the detection and understanding of protein–aptamer interaction.

A real-time and label-free strategy for bisphenol A (BPA) detection was developed using an ssDNA aptamer modified sensor combined with dual polarization interferometry (DPI). The BPA-specific aptamer, which played the role of a specific probe for recognizing and binding the target BPA, was immobilized on the surface of a sensor chip through biotin–avidin interactions. Conformational changes on the sensor surface when binding the target were monitored in real time by DPI, so that data on mass, thickness and density were obtained. Our results verified that the developed sensor had good specificity for the target, as the changes in mass, thickness and density induced by BPA were much more significant than those induced by an analogue. It was found that, with the increase of BPA concentration, the mass and thickness on the sensor surface increased while the density decreased. Both mass and thickness changes on the sensor surface showed good linearity with the BPA concentration in the range of 1–20 μM, with correlation coefficients (R2) of 0.9946 and 0.9950, respectively. This work provides a demonstration for the first time that DPI is a reliable and efficient platform for real-time and label-free detection of organic pollutants and toxicants.

We report on a novel scissor-like electromechanical metamaterial (SEMM) with enhanced and tunable damping properties, stemming from its electromechanical resonant effects. The displacement amplification mechanism of the scissor-like structure in SEMM is exploited to amplify the damping ratio for stronger vibration mitigation through the enhanced electrical dissipation of the amplified voltage of the piezoelectric element. The relative dissipation performance, termed as metadamping, is quantified based on complex band structures, which allow frequencies to be complex valued. Using different shunting circuits, the overall damping performance of SEMM is demonstrated to be higher than a statically equivalent traditional systems, such as acoustic metamaterials and monatomic lattices. The dissipation performance of SEMM is numerically verified via finite structure analysis and found to be in an excellent agreement with Bloch’s wave analysis. Furthermore, the electromechanical nature of the piezoelectric material in SEMM provides a convenient way to tune the metadamping by adjusting the piezoelectric shunting circuit.

Background High-performance position control of pneumatic artificial muscles is limited by their inherent nonlinearity and hysteresis. Objective This study aims to model the length/pressure hysteresis of a single pneumatic artificial muscle and to realize its accurate position tracking control with forward hysteresis compensation. Methods The classical Prandtl-Ishlinskii model is widely used in hysteresis modelling and compensation. But it is only effective for symmetric hysteresis. Therefore, a modified Prandtl-Ishlinskii model is built to characterize the asymmetric length/pressure hysteresis of a single pneumatic artificial muscle, by replacing the classical play operators with two more flexible elementary operators to independently describe the ascending branch and descending branch of hysteresis loops. On the basis, a position tracking controller, which is composed of cascade forward hysteresis compensation and simple proportional pressure controller, is designed for the pneumatic artificial muscle. Results Experiment results show that the MPI model can reproduce the length/pressure hysteresis of the pneumatic artificial muscle, and the proposed controller for the pneumatic artificial muscle can track the reference position signals with high accuracy. Conclusion By modelling the length/pressure hysteresis with the modified Prandtl-Ishlinskii model and using its inversion for compensation, precise position control of a single pneumatic artificial muscle is achieved.

To explore the roles of mitochondrial Uncoupling Protein 2 (UCP2) in cumulus cells (CCs), human CCs were cultured in vitro, and the UCP2 was inhibited by treatment with Genipin, a special UCP inhibitor, or by RNA interference targeting UCP2. No significant differences in adenosine triphosphate levels and the ratio of ADP/ATP were observed after UCP2 inhibition. UCP2 inhibition caused a significant increase in cellular oxidative damage, which was reflected in alterations to several key parameters, including reactive oxygen species (ROS) and lipid peroxidation levels and the ratio of reduced GSH to GSSG. UCP2 blocking resulted in an obvious increase in active Caspase-3, accompanied by the decline of proactive Caspase-3 and a significant increase in the LC3-II/LC3-I ratio, suggesting that UCP2 inhibition triggered cellular apoptosis and autophagy. The mRNA and protein expression of connexin 43 (Cx43), a gap junction channel protein, were significantly reduced after treatment with Genipin or siRNA. The progesterone level in the culture medium was also significantly decreased after UCP2 inhibition. Our data indicated that UCP2 plays highly important roles in mediating ROS production and regulating apoptosis and autophagy, as well as maintaining gap junction integrity and progesterone synthesis, which suggests that UCP2 is involved in the regulation of follicle development and early embryo implantation and implies that it might serve as a potential biomarker for oocyte quality and competency.

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the clinic, with the characteristics of occult onset, rapid progression, and high degree of malignancy. Alpha fetoprotein (AFP) is the most important biomarker of HCC, which is widely used in early screening, diagnosis, and prognosis observation. A series of immunoassays have been developed and frequently used in the detection of AFP based on antibodies. Unfortunately, the shortcomings of antibodies, such as thermal unstable and fluctuant activity by batches, lead to the inaccuracy in the detection of AFP. In this study, aptamers instead of antibodies were adopted as the specific recognition element for AFP, aiming to seek an alternative strategy to immunoassays. An AFP-specific ssDNA aptamer was grafted to magnetic nanoparticles (Fe3O4@SiO2) via avidin-biotin interaction, and the resultant aptamer functionalized magnetic nanoparticles (Ap-MNPs) were adequately characterized and tested. The Ap-MNPs in solution exhibited a fast response to the outer magnetic field, and can be completely separated in several minutes. It was found that Ap-MNPs have good specificity to the target AFP, as the recovery of AFP (87.0%) was much higher than the competitive proteins IgG (38.9%), HSA (18.5%), and FIB (11.4%). A convenient and efficient label-free detection method of AFP in serum was developed based on Ap-MNPs in combination with high-performance liquid chromatography. The linearity of this method was over a range of 1-50 μg ml-1 with a correlation coefficient of 0.9999, and the limit of detection was 0.27 μg ml-1. This study indicated that aptamers are an ideal tool for the recognition and detection of biomarkers, and thus will find wide applications in clinical practice.

All-polymer solar cells (all-PSCs) can offer unique merits of high morphological stability to thermal and mechanical stress. To realize their full potential as flexible or wearable devices, it is highly desirable that the all-PSCs can be fabricated from a green solvent with simple post-treatment to avoid thermal annealing on the flexible substrate. This posed a severe challenge on material design to tune their properties with suitable solubility, aggregation, and morphology. To address this challenge, here, a simple bicomponent random approach on a D-A-type polymer donor was developed by just varying the D-A molar ratio. Under this approach, a series of new random polymers PBDT

Desorption electrospray ionization (DESI) mass spectrometry imaging (MSI) can simultaneously record the 2D distribution of polar biomolecules in tissue slices at ambient conditions. However, sensitivity of DESI-MSI for nonpolar compounds is restricted by low ionization efficiency and strong ion suppression. In this study, a compact postphotoionization assembly combined with DESI (DESI/PI) was developed for imaging polar and nonpolar molecules in tissue sections by switching off/on a portable krypton lamp. Compared with DESI, higher signal intensities of nonpolar compounds could be detected with DESI/PI. To further increase the ionization efficiency and transport of charged ions of DESI/PI, the desorption solvent composition and gas flow in the ionization tube were optimized. In mouse brain tissue, more than 2 orders of magnitude higher signal intensities for certain neutral biomolecules like creatine, cholesterol, and GalCer lipids were obtained by DESI/PI in the positive ion mode, compared with that of DESI. In the negative ion mode, ion yields of DESI/PI for glutamine and some lipids (HexCer, PE, and PE-O) were also increased by several-fold. Moreover, nonpolar constituents in plant tissue, such as catechins in leaf shoots of tea, could also be visualized by DESI/PI. Our results indicate that DESI/PI can expand the application field of DESI to nonpolar molecules, which is important for comprehensive imaging of biomolecules in biological tissues with moderate spatial resolution at ambient conditions.

In this paper, we explore an electromechanical metastructure consisting of a periodic array of piezoelectric bimorphs with resistive-inductive loads for simultaneous harvesting and attenuation of traveling wave energy. We develop fully coupled analytical models, i.e., an electroelastic transfer matrix method, and exploit both locally-resonant and Bragg band gaps to achieve a multifunctional metastructure which is capable for maximum energy conversion and vibration mitigation in a broadband fashion. Our analytical and numerical results show that the proposed metastructure can achieve energy harvesting efficiency up to 95% at the local resonance frequency of 3.18 kHz, while reaching about 51% at 5.8 kHz near the upper limit of the Bragg band gap. The broadband vibration mitigation performance based on 50% power attenuation is predicted as 1.8 kHz and 1.1 kHz in the vicinity of the band gaps. The theoretical frameworks and the applicability of the proposed metastructure are validated using a full-scale experimental setup.

In this paper, aiming at the problem of sports injury in squatting, the development of squatting training assistant system based on MPU9250 is proposed and designed. The system uses embedded technology, through the cloud architecture of recurrent neural network to analyze data, realize the monitoring of squat training, return the results to the mobile APP end, realize the correction and guidance of each action, and display the user’s rehabilitation in real time. Through the system test, the results show that the system has the characteristics of stable performance, accurate detection, convenient and portable.

Pneumatic artificial muscles have been widely used in various fields owing to their inherent compliance and high power-to-weight ratio. However, the natural hysteresis nonlinearity including length/pressure hysteresis and force/pressure hysteresis degrades their performance in precise tracking control, making it necessary to build a mathematical hysteresis model for hysteresis compensation. This paper deals with the modelling of length/pressure hysteresis of pneumatic artificial muscles. The length/pressure hysteresis loops measured by the isotonic test are found to be asymmetric and independent of the external load when the load is small. Considering that the classical Prandtl-Ishlinskii model is only effective for symmetric hysteresis, a modified Prandtl-Ishlinskii model is proposed to describe the length/pressure hysteresis behaviour. The developed model utilizes two asymmetric operators with simple mathematical forms to independently model the ascending branch and descending branch of hysteresis loops. The model parameters are identified using the recursive least square algorithm. Comparisons between simulation results and experimental measurements demonstrate that the proposed model can characterize the asymmetric major hysteresis loop and minor hysteresis loops with high accuracy. Pnevmatične umetne mišice (PAM) so razmeroma nova vrsta elastičnih pnevmatičnih izvršnih členov. Zaradi svoje netogosti ter velikega razmerja med močjo in maso so se uveljavile na različnih področjih uporabe. Njihova naravna nelinearnost, ki vključuje histerezo dolžine/tlaka in histerezo sile/tlaka, pa povečuje sistemsko nelinearnost ter zmanjšuje sposobnost natančnega sledenja. Ena od rešitev za premostitev te težave je postavitev matematičnega modela histereze ter uporaba njegovega inverza za kompenzacijo histereze in doseganje približno linearnega odziva PAM. Članek obravnava modeliranje histereze dolžine/tlaka pri PAM. Histereza dolžine/tlaka se meri z izotoničnim testom ob predpostavki kvazistatičnosti procesa, meritve pa nakazujejo obstoj večje in manjše histerezne zanke med hitrostjo krčenja in notranjm tlakom PAM. Te histerezne zanke so asimetrične ter niso odvisne od manjših zunanjih obremenitev.

The radiated noise induced by the unsteady propeller forces is an important part of the vessel's total acoustic radiation. Therefore, understanding the role of propeller-shafting system in force transmission characteristics is necessary investigate the underwater vibro-acoustic responses of a vessel. This study compared the contribution of hull and propeller-shafting system to the radiated sound power under the propeller forces in different directions. First, a finite element/boundary element (FE/BE) model of a hull with relatively detailed substructures was developed to study the system's vibro-acoustic characteristics, in which the pulsating pressure at the propeller blade was transmitted to the hull through the propulsion system. The accuracy of the model was validated by experimental results. Second, finite element/boundary element method (FEM/BEM) was used to study the vibro-acoustic characteristics of the submerged system and the amplification effects of the propeller-shafting system. Finally, the radiated sound power of the propeller and the hull were compared, considering the flow-induced noise generated by the water surrounding the propeller. Results show that while it is reasonable to ignore the sound power generated by the elastic propeller structure, the flow-induced noise still needs to be considered, especially when the forces are applied to the propeller in the transverse and vertical directions.

Testicular dysgenesis syndrome might be due to the fetal testis defects caused by endocrine disruptors. Here, we report the combined effects of in utero exposure to cadmium (CdCl2, Cd) and di-n-butyl phthalate (DBP) on fetal testis development in rats. Pregnant Sprague-Dawley rats were randomly divided into four groups: control, Cd, DBP (250 mg/kg/day), and Cd + DBP. Cd (0.25 mg/kg/once) was intraperitoneally injected to the dam on gestational day 12 and DBP (250 mg/kg) was daily gavaged to the dam on gestational day 12 for 10 days. Cd, DBP, and Cd + DBP lowered serum testosterone levels in male fetuses. Cd and DBP did not alter fetal Leydig cell (FLC) number, but the combined exposure led to decreased FLC number. Cd did not affect FLC aggregation while DBP caused FLC aggregation and the combined exposure worsened FLC aggregation. Cd lowered FLC mRNA (Lhcgr, Star, Cyp11a1, and Insl3) levels and DBP lowered Lhcgr, Star, Insl3, and Nr5a1 levels. DBP up-regulated Scarb1 expression without affecting Cyp11a1 while the combined exposure antagonized DBP. These two chemicals and its combination did not affect Sertoli cell number and gene (Amh, Fshr, and Sox9) expression at current doses. In conclusion, the combined exposure of Cd and DBP exerts synergically antiandrogenic effects via targeting FLC development.