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In this paper, the experimental performance of a small hexapod robot driven by C-shaped legs has primarily been analyzed, based on its vertical and horizontal acceleration, for a chosen set of triangle gait phase angles. Firstly, a kinematic model was established for the hexapod robot designed by the Institute of Robotics and Intelligent Systems at Xi'an Jiaotong University. The triangle gait experiments were conducted on this robot, including straight line motion, turning motion, motion on a rugged terrain, climbing over an obstacle, and walking down a step. The acceleration during the course was plotted for each of the mentioned scenarios and the patterns were analyzed by relating to different experimental aspects. The robot achieved a maximum angular velocity of about 0.65 rad/s, crossed an obstacle of 4.5cm height and descended down a 13.5 cm high step. The analysis provides the ground towards the optimization of the triangular gait of the hexapod robot driven by C-shaped legs for robust movement.

The hexapod robot simulates the movement mode of many kinds of insects and mammals through bionics, it has a high performance in complex environment. In this paper, a bidirectional deformable foot for hexapod robot was designed, and the influence of deformable foot pitch on the maximum stress of a spring steel with deformable angle is analyzed by finite element simulation, and a prototype was designed. Finally, the motion performance of the hexapod robot was verified by using C-legged, and the synchronized gait on flat ground, triangle gait on flat ground, jumping experiment of the hexapod robot was designed, which proved that the hexapod robot could reach the expected design goal.

Generating natural language descriptions for knowledge graph (KG) is an important category for intelligent writing. Recent models on this task substitute the sequence encoder in a commonly used encoder-decoder framework with a graph encoder. However, these models suffer from entity missing and repetition. In this paper, we propose a novel end-to-end generation model named G2T, which integrates a novel Graph Structure Enhanced Mechanism (GSEM) and a Copy Coverage Loss (CCL). Instead of just considering graph structure in the encoding phase in most existing methods, our GSEM fully utilizes graph structure in the decoding phase and helps to mitigate entity missing problem. Moreover, our CCL can further improve performance by avoiding generating repeated entities. With their help, our model is capable of generating fluent description for KG. The results of automatic and human evaluations show that our model outperforms the state-of-the-art models.

Interferon-γ (IFN-γ) is a critical cytokine in the defense against viral and bacterial infection. It is mainly produced by natural killer cells and activated T cells. Given its regulatory role in coordinating cellular and humoral immune responses, IFN-γ is considered to be an effective therapeutic agent in the treatment of viral infection. Here we established a fluorescence-based high-content screening model to find small molecules that can stimulate the production of IFN-γ in human Jurkat cells. After a primary screening of 267 natural products, two hits, Astragalus polyphenols and 6-shogaol, were identified to promote the activity of the IFN-γ promoter and subsequently validated by the flow cytometry assay. Obviously, both Astragalus polyphenols and 6-shogaol exhibited potential to induce the transcription and expression of IFN-γ in a dose-dependent manner. These results indicated that our high-content screening model could be a credible and useful platform to contribute to the discovery of novel molecules to promote the expression of IFN-γ and provide leading compounds for the treatment of viral infectious diseases.

Background Studies have reported the impact of chronic childhood and adolescent tic disorder (TD) on families. However, few researches focused on the relationship between family environment and diagnosis of TD. We aim to assess the influence of couple relationship and family structure on the onset of TD. Methods A total of 660 parents of patients with TD (aged 6–12 years) and 641 parents of controls completed questionnaires. Couple relationship and family structure were selected by regression of binary logistic analysis as the risk factors. Couple relationship was divided into the harmonious, common, hostile, and divorced. Family structure included unconventional family, nuclear family, and unite family. Multivariate correspondence analysis was designed to explore relationships among categorical variables of couple relationship and family structure. Results There were significant associations between TD and couple relationship (Exp B = 1.310, p = .006, 95% CI = 1.080–1.590), family structure (Exp B = 0.668, p = .001, 95% CI = 0.526 ~ 0.847), gender (Exp B = 0.194, p, Flow diagram of data analysis.

This paper studies transceiver design for a large-scale distributed antenna system (L-DAS) with network assisted full duplexing (NAFD), where all the users and remote antenna units (RAUs) operate in either half-duplex (HD) or full-duplex (FD) mode. In the considered network, transmitting-RAUs (TRAUs) transmit information to downlink users (DUs) while receiving-RAUs (R-RAUs) receive signal from uplink users (UUs). All the T-RAUs and R-RAUs are connected to the central processor (CP) via high-speed backhaul links. T-RAUs obtain DUs’ data from the CP via downlink backhaul (D-backhaul), and forward the data to DUs by sparse beamforming. Meanwhile, R-RAUs detect the signal transmited by UUs, and forward the signal to the CP via uplink backhaul (U-backhaul). We aim to maximize the the spectral efficiency subject to quality of service (QoS) constraints and backhaul constraints. Since various design parameters, such as the downlink sparse beamformers, the uplink transmit power, and the receiver, are tightly coupled together in both the subject function and the constraints, the solution of the problem is challenging. By converting the object function to the difference between two convex functions (D.C.) structure with semi definite relax (SDR), an iterative SDR-block coordinate descent (SDR-BCD) method is proposed. Simulation results show that the proposed algorithm yield a higher spectral efficiency (SE) gain compared with the traditional time-division duple (TDD) scheme.

In recent years, Internet of things (IoT) devices are playing an important role in business, education, medical as well as in other fields. Devices connected to the Internet is much more than the number of world population. However, it may face all kinds of attacks from the Internet easily for its accessibility. As we all know, most attacks against IoT devices are based on Web applications. So protecting the security of Web services can effectively improve the situation of IoT ecosystem. Conventional Web attack detection methods highly rely on samples, and artificial intelligence detection results are uninterpretable. Hence, this article introduced a supervised detection algorithm based on benign samples. Seq2Seq algorithm is been chosen and applied to detect malicious web requests. Meanwhile, the attention mechanism is introduced to label the attack payload and highlight labeling abnormal characters. The results of experiments show that on the premise of training a benign sample, the precision of proposed model is 97.02%, and the recall is 97.60%. It explains that the model can detect Web attack requests effectively. Simultaneously, the model can label attack payload visually and make the model “interpretable.”

Air pollution has become one of the major environmental problems around the world. It is particularly serious in China due to the rapid development of the economy and industrialization. Four ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) were performed in four metropolises of China during 2019. Beijing, Nanjing, Guangzhou and Chongqing are central cities of Beijing-Tianjin-Hebei region, Yangtze River Delta, Pearl River Delta and Sichuan basin, four major polluted areas of China, respectively. In this study, vertical profiles of aerosol extinction coefficient, nitrogen dioxide (NO2) in these four cities were retrieved from MAX-DOAS. In order to understand the pollution characteristics in four major polluted areas during 2019, the averaged diurnal variation and seasonal variation of aerosol and NO2 in above four cities were performed. On the other hand, the differences of vertical structure of aerosol and NO2 in four cities were analyzed. In addition, the variation of PM2.5, PM10 and PM2.5/PM10 in above four cities during 2019 were analyzed, and it is helpful to understand the formation and source of haze occurred in the four major polluted areas. PM2.5/PM10 increasing when PM2.5 pollution became worse indicates that regional transport is the major pathway for haze. PM2.5/PM10 decreasing when PM2.5 pollution became worse indicates that primary emission and secondary chemistry are the major pathways for haze.

In wireless sensor networks (WSNs), the limited battery capacity restricts the lifetime of the sensor nodes and thus degrades the system performance. The energy harvesting and cooperation techniques are promising solutions to prolonging the battery life, by collecting energy from ambient environment and exchanging energy among sensor nodes. This paper studies the joint utility maximization problem for WSNs in consideration of energy harvesting and cooperation. We first derive an upper bound on the Lyapunov drift for the network stability, and then formulate the optimization as a stochastic optimization problem. Furthermore, we propose an energy harvesting and energy transfer, data transmission, power control, routing and scheduling (EDPR) online algorithm by combining Lyapunov optimization technique with drift-plus-penalty method and perturbation technique. It contributes to optimal utility in a distributed manner along with a balanced trade-off between network utility and queue backlog, with no need for any statistical information about dynamic systems and no concern of curse of dimensionality under large queue backlog. Simulation results also show the practicality of the proposed algorithm in real implementation since data transmission has a linear relationship with battery life.

We examine the effectiveness of corporate governance in monitoring private in-house meetings between management and investors. Consistent with better corporate governance curbing the opportunistic corporate disclosure and insider trading behavior, we find a negative association between governance quality and (i) private in-house meeting frequency, (ii) reduced insider trading frequency and value around private in-house meetings, and (iii) reduced insider trading profitability around these meetings. We document a potential channel that may explain these findings. Particularly, we find that firms with better corporate governance tend to reduce leakage of price-sensitive information during private in-house meetings, which limits the opportunity to make profitable insider trades. Our results are robust using instrumental variable and propensity score matching approaches to address endogeneity. We argue that improving corporate governance quality may be a partial substitute for costly government regulation designed to curb negative consequences of private in-house meetings.

The Shenzhen Stock Exchange (SZSE) in China is unique worldwide in requiring disclosure of the timing, participants and selected content of private in-house meetings between firm managers and outside investors. We investigate whether these private meetings benefit hosting-firms and their major outside institutional investors, mutual funds. Using a large hand-collected dataset of SZSE firms, we find that mutual funds with relatively large ownership in the hosting firm (i) have more access to private in-house meetings, particularly those meetings that reveal negative information, (ii) interact more often with top management, (iii) attend more exclusive meetings, and (iv) have longer meetings with hosting firms. When mutual funds with relatively large ownership attend negative news meetings, firms tend to experience lower post-meeting stock return volatility. This finding suggests that allowing managers and select institutional investors to discuss negative developments in a private setting – possibly to provide elaboration and manage the news – helps minimize stock sell-offs and mitigate stock return volatility.

We investigate the impact of political connection on corporate risk-taking by connected firms, their industry counterparts, as well as non-rival firms from 48 countries. We find that political connection induces higher risk taking by connected firms. By contrast, we do not find evidence that political connection, with the attendant potential competitive distortions in the industry, induces higher risk taking by competitors. We focus on non-financial industries. Our results are consistent with the hypothesis that the inability to avail themselves of political rents compels the non-connected rivals to adopt more conservative strategies. However, large rival firms, generally considered to be too-important-to-fail, exhibit evidence of higher risk taking. The top size quartile industry rivals take as much risk as the politically connected firms. The higher risk exhibited by large rivals of politically connected firms suggests that our baseline regression results of lower risk-taking among rivals of politically connected firms are biased upward by firms that would be considered too-big-to-fail. This finding also suggests that the too-big-to fail phenomenon is not unique to banks. Our results are robust to the use of alternative measures of risk, to the exclusion of privatized and state-owned firms, and to controlling for the effects of financial crisis.

Estimations of bulk hardness from nanoindentation are frequently subject to considerable uncertainties due to indentation size effects (ISE), pileup effects, and potential influence of surface quality or test methods. This study examined materials science principles of nanoindentation test methods to enable accurate prediction of bulk hardness for a series of high purity Fe and Fe-(3–25 wt%) Cr alloys. These materials were tested in as-annealed and thermally aged (100–900 h at 475 ℃ to produce Cr-rich α’ precipitates) conditions. Nanoindentation with a Berkovich indenter at constant strain rate (0.05–0.5 /s) and constant loading rate conditions provided comparable bulk equivalent hardness (H0) extracted by Nix-Gao model, indicating a weak strain rate sensitivity at room temperature. Results from electropolished and fine mechanically polished samples gave comparable measured hardness. Pileup corrections produced a 5–14% correction to H0 which agreed with the experimental bulk Vickers hardness within ∼10% for most tested materials. The microstructural model-predicted and measured strength values agreed for aged samples. A derived analytic expression demonstrates that an ISE error, associated with inappropriate methods such as hardness ratios or changes at a reference depth, would be as large as 60% in estimated bulk hardness for the investigated Fe-Cr alloys.

Adhesion plays a critical role in the reliability of the micro devices in MEMS. However, the quality of the micro devices fabricated by electroforming technology is influenced by the poor a...

This study examines whether financial dependence upon a few customers is negatively related to the allocation of innovation resources of supplier firms. Furthermore, this study investigates whether these negative effects of supplier dependence on research and development (R&D) intensity are reduced when the supplier leverages social capital conceptualized in terms of eigenvector centrality and interconnectedness. Using panel data, we find that a supplier firm's dependence upon major customers has a negative relationship with the supplier firm's R&D intensity. Our results, however, reveal that a dependent supplier having high eigenvector centrality or working with other companies that are densely connected to each other mitigates the negative effects of supplier dependence on R&D intensity. These findings highlight the importance of external information or resources being available in supply networks when suppliers that are dependent upon major customers explore and exploit opportunities for new product development.

Overcoming multidrug resistance has always been a major challenge in cancer treatment. Recent evidence suggested epithelial-mesenchymal transition plays a role in MDR, but the mechanism behind this link remains unclear. We found that the expression of multiple ABC transporters was elevated in concordance with an increased drug efflux in cancer cells during EMT. The metastasis-related angiopoietin-like 4 (ANGPTL4) elevates cellular ATP to transcriptionally upregulate ABC transporters expression via the Myc and NF-κB signaling pathways. ANGPTL4 deficiency reduced IC50 of anti-tumor drugs and enhanced apoptosis of cancer cells. In vivo suppression of ANGPTL4 led to higher accumulation of cisplatin-DNA adducts in primary and metastasized tumors, and a reduced metastatic tumor load. ANGPTL4 empowered cancer cells metabolic flexibility during EMT, securing ample cellular energy that fuels multiple ABC transporters to confer EMT-mediated chemoresistance. It suggests that metabolic strategies aimed at suppressing ABC transporters along with energy deprivation of EMT cancer cells may overcome drug resistance. Electronic supplementary material The online version of this article (10.1186/s12943-018-0904-z) contains supplementary material, which is available to authorized users.

To investigate the contribution of de novo variants to Tourette disorder (TD) probands in China. Whole-exome sequencing (WES) conducted on 15 child-parent trios (45 samples) detected 25 coding de n...

Compared to conventional speech synthesis, end-to-end speech synthesis has achieved much better naturalness with more simplified system building pipeline. End-to-end framework can generate natural speech directly from characters for English. But for other languages like Chinese, recent studies have indicated that extra engineering features are still needed for model robustness and naturalness, e.g, word boundaries and prosody boundaries, which makes the front-end pipeline as complicated as the traditional approach. To maintain the naturalness of generated speech and discard language-specific expertise as much as possible, in Mandarin TTS, we introduce a novel self-attention based encoder with learnable Gaussian bias in Tacotron. We evaluate different systems with and without complex prosody information and results show that the proposed approach has the ability to generate stable and natural speech with minimum language-dependent front-end modules.

In this paper, delay and energy efficiency (EE) are investigated in three-tier fog radio access networks (F-RANs) with hybrid caching. By using tools from stochastic geometry, we firstly derive tractable expressions of delay for coded cached, non-partitioned cached and uncached files. Then, we derive tractable expressions of EE by jointly considering power consumed in circuits, transmissions and backhaul links. To balance delay and EE, the corresponding multi-objective optimization problem is formulated to obtain the optimal hybrid caching strategy. Numerical results show the flexibility of the proposed optimal hybrid caching strategy in delay-sensitive and EE-sensitive scenarios, and that fog access point (F-AP) density has a more significant impact on delay-sensitive scenarios than EE-sensitive scenarios.

A highly solvatochromic fluorophore naphthalimide bearing malononitrile (MN) was designed and synthesized. The fluorescence emissions and absorption of MN showed a large bathochromic shift from 380/325 nm to 620/520 nm with increasing solvent polarity. The solvatochromism was attributed to solvent-controlled tautomerism of MN. The intramolecular proton transfer reaction paly important role in isomer formation. The isomers of MN were characterized by 1HNMR and Dept135. The solvatochromism was further studied by calculated molecular orbital energy and dipole moment vectors.

Approximately 30% of human cancers are associated with RAS mutation. Ras proteins on the plasma membrane regulate a plenty of important cellular processes. The post-translational modifications (PTMs) of Ras proteins like lipidation and methylation are crucial for their correct cellular localization and biological function. Hence, obtaining Ras proteins with different kinds of modifications is the necessary prerequisite to investigate their biological properties at molecular level. In this review, we mainly summarize the developed strategies including chemical total synthesis, biosynthesis and semi-synthesis for producing Ras proteins with modifications and their application in biological studies.

Pre-stressed carbon fiber reinforced polymer (CFRP) tendon system is developed. Extrusion method guarantees the strength of the CFRP tendon could be fully used in strengthening. The pre-stressed CFRP tendons are applied to strengthen aluminum beams and portable aluminum bridge to improve the flexural rigidity and load carrying capacity of these structures and the improvements are revealed by the experiments. Applying extruded CFRP tendon-anchor system, the load carrying ability of the pre-stressed aluminum bridge has an improvement of 25%. Structural models are proposed to investigate the pre-stressing effects, including the deflection and the load capacity under different design criteria. Finite element method (FEM) is applied to analyze the nonlinear behavior of the pre-stressed beam and reveal the plastic torsional buckling failure style. All these analyses agree well with the experiments and suggest accurate methods to design pre-stressed aluminum/CFRP structures.

CO2-responsive and photopolymerizable prepolymers are designed and synthesized. Their good photopolymerization kinetics and reversible CO2 and N2 responses to a bulk state and in a solution are reported. Stepwise modulation is verified in template imprinting. Results reveal that stable and high-resolution patterns can be produced by imprinting liquid prepolymers in CO2 atmosphere, erased by warm heating, or retained permanently by chemical cross-linking through photopolymerization with the aid of a photoinitiator. By contrast, only blurry patterns are obtained in air.

We examine information content and related insider trading around private in-house meetings between corporate insiders and investors and analysts. We use a hand-collected dataset of approximately 17,000 private meeting summary reports of Shenzhen Stock Exchange firms over 2012–2014. We find that these private meetings are informative and corporate insiders conducted over one-half of their stock sales (totaling $8.7 billion) around these meetings. Some insiders time their transactions and earn substantial gains by selling (purchasing) relatively more shares before bad (good) news disclosures while postponing selling (purchasing) when good (bad) news is to be disclosed in the meeting. Finally, we conduct a content analysis of published meeting summary reports and find that the tone in these reports is associated with stock market reactions around (1) private meetings themselves, (2) subsequent public release of private meeting details, (3) subsequent earnings announcements and (4) future stock performance.

Research into the preparation and application of metal/graphene nanocomposite materials is an important issue in the field of graphene applications. Metal nanomaterials and graphene materials have many excellent properties and have been perfectly combined into metal/graphene nanocomposite materials. These offer the high catalytic activity of metal nanomaterials and the high specific surface area and favorable electrical conductivity of graphene. The unique advantages can produce synergistic effects and can significantly improve the overall performance of the composite materials. This gives the metal/graphene nanocomposite materials excellent application prospects for hydrogen evolution. Here, we report the preparation of yttrium-doped palladium/iron on graphene (Pd/YFeO3/GC) using a simple and efficient method. The catalytic performance of the Pd/YFeO3/GC nanocomposites for water electrolysis and hydrogen production was evaluated. The results show that the overpotential for the hydrogen evolution reaction at −10 mA cm−2 is only 15 mV, which is competitive with Pt/C catalysts. The Pd/YFeO3/GC is highly active for hydrogen evolution with an onset potential of −8 mV in 0.5 M H2SO4 solution and a Tafel slope of 37 mV dec−1 with a Pd loading of only 20 μgPd cm−2. These results clearly demonstrated that Pd/YFeO3/GC is an excellent catalyst for hydrogen evolution.

To cope with the exploding demand for higher data rate and the heavier asymmetry of downlink (DL) and uplink (UL) traffic, dynamic time-division duplex (DTDD) has been proposed, where the time resources can be adjusted dynamically between DL and UL transmission. However, the strict synchronization requirements in DTDD bring extra overhead. In this paper, a bidirectional dynamic network (BDN) with massive multiple input multiple output is studied, in which DL and UL transmission can occur simultaneously. Under imperfect channel-state information, the closed-form expressions for the UL achievable rates with maximum ratio combination (MRC) and zero-forcing (ZF) receivers as well as the DL achievable rates with maximum ratio transmission (MRT) and ZF beamforming are derived in both BDN and DTDD systems. Based on these expressions, we compare the spectral efficiency of BDN and DTDD systems. Numerical results show that the simulation results match well with the closed-form expressions in both BDN and DTDD systems. Furthermore, BDN is more spectral efficient than DTDD. ZF achieves better performance in spectral efficiency than MRC and MRT.

This paper investigates the joint beamforming and power splitting factor optimization in distributed multiple input single output systems with power-splitting simultaneous wireless information and power transfer (SWIPT). We assume that all the user equipment (UEs) perform data transmission, whereas only UEs with sufficient large scale fading, defined as SWIPT UEs, also conduct energy harvesting. System total power consumption minimization problem is formulated with per-UE quality of service (QoS) constraints and minimal harvesting power constraints for SWIPT UEs with the consideration of RAU selection. First, we classify the UEs into two groups according to the large scale fading criterion. Then for perfect channel state information (CSI), the optimal problem is formulated and approximated by transforming RAU mode indicator function into reweighted ℓ0-norm. Semi-definite relaxed method is used and an iterative algorithm is proposed. Furthermore, we consider the optimization with imperfect CSI and change the constraints to the worst case. To guarantee the rank-one constraint, an iterative function based on penalty function is proposed. Simulations show that the proposed algorithms with RAU selection can significantly reduce system total power consumption and also reveal that the RAU closest to SWIPT UEs tends to be active.

In this paper, we study the energy-efficiency (EE) maximization problem for a multiple-input multiple-output distributed antenna system (DAS) with pilot contamination. With per-user quality of service constraints and per remote antenna unit (RAU) power requirements, we formulate the EE maximization problem as a joint optimization of sparse transmit beamforming, RAU selection, and RAU clustering. The considered problem is a non-convex multivariate optimization problem. To solve the problem, we transform it to an equivalent parametric programming problem (PPP) with a given EE parameter and design a two-layer optimization scheme to solve the original problem. The outer layer involves two kinds of algorithms to iteratively update the EE parameter based on Dinkelbach’s algorithm and bi-section search, respectively. The more challenging issue lies in the inner loop, where a non-convex multivariate PPP needs to be tackled. A series of techniques, including the reweighted $\ell_\mathbf {1}$ -norm, D.C. function, and semidefinite relaxation (SDR), is adopted to approximate the non-convex multivariate PPP with a convex SDR problem. Furthermore, a heuristic algorithm is proposed to reduce the complexity of a two-layer scheme. Simulation results show that the proposed algorithms significantly improve the EE and demonstrate that RAU selection and RAU clustering contribute to a higher EE.

The downlink training yields rather modest performance gains due to the high degree of channel hardening effect in co-located large-scale multi-input multi-output (MIMO) systems. However, in distributed large-scale MIMO systems, the potential benefits of the downlink training become larger, since there is a high probability that each user is very close to only a part of remote antenna units and is effectively served by them which results in less channel hardening effect. In this paper, we study the benefits of the beamforming training (BT) scheme (users estimate the channel state information by using the received training symbols, which are processed by linear beamforming in advance) in distributed large-scale MIMO systems. We derive accurate and tractable closed-form analytical expressions for the spectral efficiency (SE) of the BT scheme in distributed large-scale MIMO systems with maximum ratio transmission and zero-forcing (ZF) beamforming. Based on these expressions, we analyze the benefits of the BT scheme and investigate how the number of transmit antennas and the length of coherence interval affect the SE of the BT scheme in the co-located and distributed large-scale MIMO systems. The analytical results show that the BT scheme is more suitable for distributed large-scale MIMO systems with ZF beamforming, and a less number of transmit antennas and longer coherence interval can improve the performance gain of BT scheme.

We test news media's disciplining by dissemination role and predictive power in insider trading related issues with a large and novel dataset on Chinese firms between 2008 and 2017. We find that more media coverage is associated with significantly lower level of insider trading profitability, which confirms the disciplining by dissemination role of media documented in the developed market. However, as a new evidence to the media and insider trading literature, we also find that media's negative tone has a positive correlation with future insider trading profitability, which is consistent with the media predictive power argument. In addition, we find that media's predictive power is amplified by a firm's good governance structure and low level of information asymmetry. Our study shows news media's effectiveness in predicting opportunistic insider trading in China.

Two-dimensional transition metal disulfides are considered a great candidate for non-noble metal catalyst because of their abundant reserves and excellent electrochemical activity in hydrogen evolution reaction (HER). Herein, two-dimensional (2D) few-layer WS2 nanosheets were synthesized via a facile liquid phase stripping technique. The piezoelectricity of the synthesized WS2 nanosheets was verified by piezoelectric force microscope (PFM) and used to promote the piezo-catalytic hydrogen generation, where the piezoelectric charges generated under ultrasound vibration are utilized for hydrogen evolution. Moreover, the effect of various mechanical vibration conditions on the piezo-catalytic HER of WS2 was also discussed. The results show that under the same overpotential, the hydrogen production rate with ultrasound vibration (40 kHz, 40 W) is 6 times higher and the impedance is 4 times lower than that without ultrasound. The catalytic efficiency of WS2 can be significantly increased through this method, which paves the way towards non-noble metal HER catalysts to produce hydrogen with aid of piezoelectricity.

Using a novel text-based measure of financial constraints and primarily employing firm fixed-effect model, we find that financial constraints have a significantly negative association with cash conversion cycle (CCC), implying that financially constrained firms have a higher level of working capital management efficiency. In order to get a deeper insight, we consider two distinct dimensions, − ‘growth oriented’ and ‘contractual-obligation oriented’ financial constraints - and re-examine the relationship with CCC and its components. We find that firms facing growth oriented (contractual-obligation oriented) financial constraints have shorter (longer) CCC. It appears that compared to contractual-obligation oriented financially constrained firms, growth-oriented constrained firms receive more favorable treatments from their suppliers (longer payable period) as well as from their customers (shorter receivable period) - leading to a lower CCC. On the other hand, contractual-obligation oriented financially constrained firms have a longer inventory period, resulting in a longer CCC.

The pursuit of better electrochemical sensors highlights the requirements for new sensor designs and electrode materials. The concept of ‘limiting current sensor’ has been validated but confined in gas detection. Herein, we applied the concept of ‘limiting current sensor’ to ions detection in aqueous solutions. A limiting current sensor prototype has been developed for the detection of two potentially hazardous ions, ferricyanide and ferrocyanide, which are widely used in nuclear wastewater treatment, food production and energy generation. The limiting current sensor consists of a three-electrode electrochemical cell equipped with a porous Ni working electrode and a pumping system. The pumping system forces the solution containing ferricyanide/ferrocyanide to flow through the porous Ni electrode, markedly increasing the mass transfer rate. The enhanced mass transfer rate, together with the high surface area of the porous Ni working electrode, increases the reaction rate and in turn improves the detection performance. The limiting current sensor shows two orders of magnitude higher sensitivity and one order of magnitude lower limit of detection than previously reported sensors and exhibits excellent thermal stability, long-term stability and selectivity. The limiting current sensor design can be extended to the detection of other ions or molecules.

In this paper, the closed-form parameterizations to the Pareto boundary for the two-user multiple-input single-output interference channel are studied. Firstly, for the equivalent channel model with each transmitter having only two antennas, the weighted sum-rate maximization (WSRMax) problem is reformulated with newly defined angle variables. Then, a centralized weighted leakage-plus-noise-to-signal ratio minimization (WLNSRMin) algorithm is proposed to find a locally optimal weighted sum-rate point. Each step of the algorithm is solved by evaluating closed-form expressions. A distributed algorithm is also given to avoid the exchange of the channel state information (CSI) between transmitters. Numerical results show that the centralized WLNSRMin algorithm converges to a local optimum of the WSRMax problem after a few iterations and the distributed algorithm achieves a performance very close to that of the centralized algorithm with only local CSI.

This study examines how extraversion, a personality trait that signifies more or less positive affect, assertive behavior, decisive thinking, and desires for social engagement, influences Chief Executive Officer (CEO) decisions, and ensuing strategic behavior of firms. Using a nov-el linguistic technique to assess personality from unscripted text spoken by 2,381 CEOs of S&P 1500-listed firms during quarterly earnings conference calls over a ten-year timespan, we show that CEO extraversion has an important bearing on the M&A behavior of firms above and be-yond other well-established personality traits. Specifically, we find that extraverted CEOs are more likely to engage in acquisitions, and conduct larger ones, and that these effects are par-tially explained by their higher representation on boards of other firms. Moreover, we find that the acquisitive nature of extraverted CEOs reveals itself particularly under so-called “weaker” situations, when CEOs enjoy considerable discretion to behave in manners that are akin to their personality traits. Subsequent analyses also show that extraverted CEOs are more likely to suc-ceed in M&As, as reflected in stronger abnormal returns following acquisition announcements.

In this paper, considering the practical channel impairments known as pilot contamination and channel aging induced by both Doppler shift and phase noise, we analyze the uplink spectral efficiency of multi-cell multi-user distributed massive multi-input multi-output (MIMO) systems with linear receivers. A joint channel model is first provided, which allows studying the impacts of these impairments on the achievable rate performance of distributed massive MIMO systems simultaneously. Based on this model, using the properties of Gamma distributions together with the approximate methods for non-isotropic vectors, we derive tractable but accurate closed-form expressions for the uplink achievable rate with maximum ratio combining (MRC) and zero-forcing (ZF) receivers in distributed massive MIMO systems. User ultimate achievable rate is also given when the ratio of total number of transmit antennas to the number of users is very large. It is shown that MRC and ZF receivers achieve the same ultimate achievable rate in the presence of the practical channel impairments. Numerical results show that channel aging has a greater impact on ZF receiver and the impact of the Doppler shift is more detrimental than that of the phase noise.

To obtain highly effective antifouling coatings, a series of functional ternary copolymers grafted with short fluoroalkyl or perfluoropolyether modified fluorinated aromatic side chains and cross-linkable functional groups were prepared via radical polymerization. Nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) were used to characterize the fluoropolymers. The surface properties of the fluoropolymer coatings on cotton fabric, aluminum plates and glass slides were studied. The results indicate that the fluoropolymers show good thermal stabilities (Td > 303 °C), and the hydrophobicity of the fluoropolymer coatings was increased with the increase of fluorinated monomer content (water contact angle on cotton fabric was up to 144°). The antifouling characteristics were investigated by Escherichia coli and Staphylococcus aureus attachment studies. The fluoropolymers exhibited excellent antibacterial activity against E. coli and S. Aureus. The fluoropolymers might be used as promising environmentally benign marine antifouling coating materials due to their high thermal stability, hydrophobicity and antifouling effect.

Wireless energy transfer is a promising solution to provide convenient and steady energy supplies for low-power relays. This paper investigates the simultaneous information and energy transfer in fading relay channels, where the relay has no fixed energy supply and replenishes energy from radio frequency signals transmitted by the source. Assume that the relay can switch among energy harvesting, information decoding, and information retransmission in each channel fading state. Our objective is to maximize the ergodic throughput by optimizing the mode switching rule and transmit power jointly under the data and energy causality constraints. When the source knows channel state information (CSI) of all links, to make the problem tractable, for the relay, we neglect the causality constraints during the transmission, and only consider the total data and energy constraints. We thus obtain an upper bound on the ergodic throughput by solving a convex optimization problem. Numerical results show that the achievable rate is very close to the upper bound when we apply the optimized parameters to a practical system. When the source only knows CSI of partial links, the whole transmission process is divided into two phases: the source transmits in the first phase and the relay decodes and forwards received bits using the harvested energy in the second phase. The throughput maximization problem is solved by combing convex optimization, fractional programming, and linear search. We also consider the simplified network topology when a direct link between the source and destination is unavailable. In this network, we propose algorithms based on bisection method to obtain the optimal parameters in information/energy transfer scheduling and power control when the source knows full or partial CSI. The simulation results reveal that the throughput gain brought by wireless powered relaying in different system configurations when the source knows full or partial CSI. Moreover, the effect of the relay position is discussed.

To improve the power factor and reliability for medium/high-power supply, a three-phase single-stage ac–dc converter based on magnetic-combination transformer with power factor correction (PFC) function is presented in this paper. According to the three-phase instantaneous power balance principle and the concept of the magnetic-flux superposition, a novel magnetic-combination transformer is proposed, which can make three-phase symmetrically and sinusoidally fluctuant power add to be constant. Therefore, the induced voltage of the secondary winding is constant. To realize sinusoidally fluctuant power in the input stage, dc-link filter capacitance can be reduced to a several-microfarad level. Single-stage PFC function, no electrolytic capacitor, and constant output voltage can be realized in the converter. The principle and the structure of the novel magnetic-combination transformer are analyzed in detail in this paper. Simulation and experimental results are presented to verify the feasibility of the proposed converter.

Owing to multiple antibiotic resistance

A novel class of solid-emissive boron-difluoride derivatives, using phenanthrenequinone hydrazone as ligands, were designed and efficiently synthesized. These dyes exhibit weak fluorescence in dilute solutions, but much higher fluorescence efficiency in aggregate states with a large stokes shift (over 70 nm) due to the their aggregation-induced emission enhancement (AIEE) characteristics. According to their photophysical properties and X-ray single crystal structure analysis, the AIEE was ascribed to the H(J)-aggregate formation aided by multiple intermolecular interactions to restrict intramolecular motion in the solid state. Moreover, their solid emissions could be reversibly tuned between “on” and “off” by mechanical grinding and recrystallization, due to the stacking model transition between H(J)-aggregation with loose molecular packing and J-aggregation with intense intermolecular interactions.

Lung cancer remains the leading cancer killer worldwide. Early diagnosis can effectively increase the patient cure rate but existing diagnostic methods limit early lung cancer diagnosis. Therefore, development of a simple but efficient lung cancer screening method is important to improvement of both the diagnosis rate and the survival rate of lung cancer patients. In this study, ten photosensitive materials with high sensitivity and high specificity were screened accurately to construct a microarray sensor that can rapidly identify six types of lung cancer biomarkers in exhaled breath. Results from hierarchical cluster analysis (HCA), principal component analysis (PCA) and difference maps showed that the classification of the analytes agreed with structure similarity laws. The detection results from parallel experiments and structurally similar analytes, in turn, cluster into a group; the fingerprints of the different analytes have specific response regions. The well-screened sensor chip fabrication workload and cost were both reduced by approximately two thirds, while the microfluidic device sensitivity and stability increased by approximately 1.3 times their corresponding values before optimization. The dual-channel device also offers real-time contrast detection and synchronous parallel detection functions and has potential application prospects for use in extensive screening of high-risk populations for lung cancer.

Despite extensive global efforts, secondary bacterial pneumonia still represents a major cause of death in developing countries and is an important cause of long-term functional disability arising from lung tissue damage. Newer approaches to improving treatment outcomes are needed to reduce the significant morbidity and mortality caused by infectious diseases. Our study, using an experimental mouse model of secondary S. pneumoniae infection, shows that a multimodal treatment that concurrently targets host and pathogen factors improved lung tissue integrity and extended the median survival time of infected mice. The immunoneutralization of host protein cANGPTL4 reduced the severity of pulmonary edema and damage. We show that host-directed therapeutic strategies as well as neutralizing antibodies against pathogen virulence factors are viable adjuncts to standard antimicrobial treatments such as antibiotics. In view of their different modes of action compared to antibiotics, concurrent immunotherapies using antibodies are potentially efficacious against secondary pneumococcal pneumonia caused by antibiotic-resistant pathogens., Secondary bacterial lung infection by Streptococcus pneumoniae (S. pneumoniae) poses a serious health concern, especially in developing countries. We posit that the emergence of multiantibiotic-resistant strains will jeopardize current treatments in these regions. Deaths arising from secondary infections are more often associated with acute lung injury, a common consequence of hypercytokinemia, than with the infection per se. Given that secondary bacterial pneumonia often has a poor prognosis, newer approaches to improve treatment outcomes are urgently needed to reduce the high levels of morbidity and mortality. Using a sequential dual-infection mouse model of secondary bacterial lung infection, we show that host-directed therapy via immunoneutralization of the angiopoietin-like 4 c-isoform (cANGPTL4) reduced pulmonary edema and damage in infected mice. RNA sequencing analysis revealed that anti-cANGPTL4 treatment improved immune and coagulation functions and reduced internal bleeding and edema. Importantly, anti-cANGPTL4 antibody, when used concurrently with either conventional antibiotics or antipneumolysin antibody, prolonged the median survival of mice compared to monotherapy. Anti-cANGPTL4 treatment enhanced immune cell phagocytosis of bacteria while restricting excessive inflammation. This modification of immune responses improved the disease outcomes of secondary pneumococcal pneumonia. Taken together, our study emphasizes that host-directed therapeutic strategies are viable adjuncts to standard antimicrobial treatments.

Exoskeleton robot is a system with human-machine interaction and could help human to carry heavy load. Series elastic actuators (SEAs) in force-controlled robots can achieve compliant interactions with humans. In order to get flexible position and force control, this paper introduced impedance control into exoskeleton robot and use a recurrent neural network to improve the adaptive ability of the system. Finally, simulation results of force tracking and trajectory tracking are presented. By setting virtual impedance parameters, this controller can achieve stable track tracking and force tracking. Recurrent neural network can improve the performance of adaptability and robustness.

Aiming at the existing problems of high-voltage transmission line inspection robot, such as large size, low obstacle crossing efficiency, and inability to cross over obstacles such as diversion lines and insulators, this paper presents a two-arm swinging inspection robot based on primates by observing the movement characteristics of gibbons and combining with the principle of bionics. The robot can swing cantilever on the high-voltage line to achieve obstacle crossing. After kinematics analysis of the bionic model of the inspection robot, the 3d model of the robot is established in SolidWorks. Simulation analysis of the robot is carried out through the built-in motion plug-in to ensure that the robot can achieve the desired motion effect, which verifies the stability and rationality of the mechanism design.

In view of the difficulties in modeling, large external interference, weak adaptability and other problems in the control strategy adopted by the lower limb exoskeleton robot for medical rehabilitation at the present stage. This paper applies the bionic control method based on CPG to the exoskeleton control of lower limb rehabilitation. By adopting Dynamic Hebbian learning algorithm to improve the Hopf oscillator. And build a CPG oscillator network, realize the gait signal study, and eventually to improve lower limb exoskeleton robot movement performance and enhance its adaptability. Through the patient's wear-wearing test. It is proved that CPG bionic control exoskeleton can be matched with the control signal of the limb produced by the human body in the case of the human body motion cycle, and it can effectively control the exoskeleton of the lower extremity and to perform rehabilitation exercises.

Network assisted full-duplex (NAFD) is a spatial-division duplex technique for future wireless networks with cell-free massive multiple-input multiple-output (CF massive MIMO) network, where a large number of remote antenna units (RAUs), either using half-duplex or full-duplex, jointly support truly flexible duplex including time-division duplex, frequency-division duplex and full duplex on demand of uplink and downlink traffic by using network MIMO methods. With NAFD, bi-directional data rates of the wireless network could be increased and end-to-end delay could be reduced. In this paper, the spectral efficiency of NAFD communications in CF massive MIMO network with imperfect channel state information (CSI) is investigated under spatial correlated channels. Based on large dimensional random matrix theory, the deterministic equivalents for the uplink sum-rate with minimum-mean-square-error (MMSE) receiver as well as the downlink sum-rate with zero-forcing (ZF) and regularized zero-forcing (RZF) beamforming are derived. Numerical results show that under various environmental settings, the deterministic equivalents are accurate in both a large-scale system and system with a finite number of antennas. It is also shown that with the downlink-to-uplink interference cancellation, the uplink spectral efficiency of CF massive MIMO with NAFD could be improved. The spectral efficiencies of NAFD with different duplex configurations such as in-band full-duplex, and half-duplex are compared. With the same total numbers of transmit and receive antennas, NAFD with half-duplex RAUs offers a higher spectral efficiency. To alleviate the uplink-to-downlink interference, a novel genetic algorithm based user scheduling strategy (GAS) is proposed. Simulation results show that the achievable downlink sum-rate by using the GAS is greatly improved compared to that by using the random user scheduling.