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The heterogeneous magnesium (Mg) matrix nanocomposite with dispersed soft phase exhibits high strength and toughness. Herein, the deformation behavior and failure process were investigated to reveal the unique mechanical behavior of the heterogeneous microstructure under compression. The extensive plastic deformation is accompanied by the flattening and tilting of the soft phase, inhibiting strain localization and leading to strain hardening. Moreover, a stable crack multiplication process is activated, which endows high damage tolerance to the heterogeneous Mg matrix nanocomposites. The final failure of the composite is caused by crack coalescence in the shear plane along a tortuous path. The presence of dispersed soft phases within the hard matrix induces a noticeable change in mechanical response. Especially, the malleability of the heterogeneous Mg matrix nanocomposite is two and ten times higher than that of pure Mg and the homogeneous Mg matrix nanocomposite, respectively. The current study provides a novel strategy to break the trade-off between strength and toughness in metal matrix nanocomposites.

The valence-combination strategy was applied to design B-site substitution non-equimolar stoichiometric high-entropy perovskite oxides (HEPOs). 29, 56 and 29 valence combinations with the maximum configurational entropy higher than 1.5R for five-component HEPOs were identified when the average valence of B-site is 3, 4 and 5, respectively. Synthesis experiment was performed on 8 valence combinations with the average valence of B-site equal to 4. Single-phase HEPOs were obtained from 6 of them. It was also found that most of HEPOs have ordered structures. The formation of single-phase HEPO and ordered structure was discussed in terms of structural tolerance factor and valence-difference factor.

The effect of oscillatory pressure on the sintering behavior and mechanical properties of alumina ceramics was studied at different stages of sintering. Compared to ceramics prepared via conventional hot pressing, samples consolidated by hot oscillatory pressing exhibit the higher density and smaller grain size along with superior hardness and fracture strength. The oscillatory pressure was beneficial to improve the sintering behavior of alumina ceramics, which was independently of the step of sintering. Furthermore, the higher was the temperature at which the oscillatory pressure was applied, the better were the mechanical properties and, consequently, the performance of ceramics.

SiCw-Al2O3-YAG ceramic composites were prepared by hot oscillatory pressing (HOP) and traditional hot pressing (HP). The results showed that compared with static pressure, the oscillatory pressure could effectively promote densification and mechanical properties of the composites. The sample prepared by HOP exhibited higher hardness (15.72 ± 0.20 GPa) and fracture toughness (7.13 ± 0.19 MPa m1/2). The current work suggests that HOP could be an effective technique for the preparation of whisker reinforced ceramic composites.

The microstructural evolution of dense Al2O3–Y3Al5O12 (YAG) composites exposed to an electric field treatment has been investigated. In particular, the transformation of the initially homogenous composite structure into three different regions has been observed, including (1) the composite structure region, (2) the eutectic region, and (3) the segregation region. In addition, pores and holes have been introduced into a dense structure of the sample after the electric field treatment. The observed phenomena have been interpreted in terms of the electromigration mechanism induced by the high electric field, rather than the melting caused by the Joule heating of the composites. The results indicate the potential of electric field treatment as a new post-processing method to optimize microstructure and properties during ceramic manufacturing.

In this paper, we explored the possibility of forming single-phase high-entropy fluorite oxides (HEFOs) in the (Ce0.2Zr0.2Ti0.2Sn0.2M0.2)O2-δ (M = Mg, Y, Yb, and Ca) system. The result showed that single-phase high-entropy fluorite can only be obtained from (Ce0.2Zr0.2Ti0.2Sn0.2Ca0.2)O2-δ. Compared with other reported anion-deficient HEFOs, this material has the lowest rare earth element content, the smallest average cationic radius and the lowest theoretical density. The effects of cation radius and starting materials on the formation of single-phase HEFOs are discussed.

Background In brown algae, dioicy is the prevalent sexual system, and phenotypic differences between male and female gametophytes have been found in many dioicous species. Saccharina japonica show remarkable sexual dimorphism in gametophytes before gametogenesis. A higher level of phenotypic differentiation was also found in female and male gametes after gametogenesis. However, the patterns of differential gene expression throughout gametophyte development and how these changes might relate to sex-specific fitness at the gamete stage in S. japonica are not well known. Results In this study, differences in gene expression between male and female gametophytes in different developmental stages were investigated using comparative transcriptome analysis. Among the 20,151 genes expressed in the haploid gametophyte generation, 37.53% were sex-biased. The abundance of sex-biased genes in mature gametophytes was much higher than that in immature gametophytes, and more male-biased than female-biased genes were observed in the mature stage. The predicted functions of most sex-biased genes were closely related to the sex-specific characteristics of gametes, including cell wall biosynthesis, sperm motility, and sperm and egg recognition. In addition, 51 genes were specifically expressed in males in both stages, showing great potential as candidate male sex-determining region (SDR) genes. Conclusions This study describes a thorough investigation into differential gene expression between male and female gametophytes in the dioicous kelp S. japonica. A large number of sex-biased genes in mature gametophytes may be associated with the divergence of phenotypic traits and physiological functions between female gametes (eggs) and male gametes (sperm) during sexual differentiation. These genes may mainly come from new sex-biased genes that have recently evolved in the S. japonica lineage. The duplication of sex-biased genes was detected, which may increase the number of sex-biased genes after gametogenesis in S. japonica to some extent. The excess of male-biased genes over female-biased genes in the mature stage may reflect the different levels of sexual selection across sexes. This study deepens our understanding of the regulation of sex development and differentiation in the dioicous kelp S. japonica.

The WC-6Co cemented carbides were sintered using hot oscillating pressing (HOP) method. The interplay of sintering parameters between microstructure and mechanical properties were systematically investigated. Results revealed that HOP could enhance the densification, restrain grain growth, shorten Co matrix average free path, and accelerate Co distribution in WC-6Co cemented carbides, which improved the combined performance for hardness of 25.22 Gpa and fracture toughness of 12.89 MPa m1/2 after sintering at 1400 °C. It is worth emphasizing that these mechanical properties are better than similar cemented carbides prepared by conventional methods, indicating the promise of utilizing HOP for high-performance cemented carbides.

Charge transport in a single-molecule junction is extraordinarily sensitive to both the internal electronic structure of a molecule and its microscopic environment. Two distinct conductance states of a prototype terphenyl molecule are observed, which correspond to the bistability of outer phenyl rings at each end. An azobenzene unit is intentionally introduced through atomically precise side-functionalization at the central ring of the terphenyl, which is reversibly isomerized between trans and cis forms by either electric or optical stimuli. Both experiment and theory demonstrate that the azobenzene side-group delicately modulates charge transport in the backbone via a single-molecule stereoelectronic effect. We reveal that the dihedral angle between the central and outer phenyl ring, as well as the corresponding rotation barrier, is subtly controlled by isomerization, while the behaviors of the phenyl ring away from the azobenzene are hardly affected. This tunability offers a new route to precisely engineer multiconfigurational single-molecule memories, switches, and sensors.

Medium-entropy oxides, ((Mg1/3Co1/3Ni1/3)1-xZnx)O with x between 0.292 and 0.388, were synthesized by sintering the corresponding powder mixtures and proven to be entropy stabilized. The enthalpy of mixing of these oxides was estimated from their critical formation temperatures. The result showed that the enthalpy of mixing was linearly related to the ZnO concentration. The critical temperature for other compositions in the system was estimated using the extrapolated mixing enthalpy. It is found that the predicted Tc is consistent with experimental results.

Chemodynamic therapy is an emerging tumor therapeutic strategy. However, the anticancer effects are greatly limited by the strong acidity requirements for effective Fenton-like reaction, and the inevitably "off-target" toxicity. Herein, we develop an acidity-unlocked nanoplatform (FePt@FeOx @TAM-PEG) that can accurately perform the high-efficient and tumor-specific catalysis for anticancer treatment, through dual pathway of cyclic amplification strategy. Notably, the pH-responsive peculiarity of tamoxifen (TAM) drug allows for the catalytic activity of FePt@FeOx to be "turn-on" in acidic tumor microenvironments, while keeping silence in neutral condition. Importantly, the released TAM within cancer cells is able to inhibit mitochondrial complex I, leading to the upregulated lactate content and thereby the accumulated intracellular H+ , which can overcome the intrinsically insufficient acidity of tumor. Through the positive feedback loop, large amount of active FePt@FeOx nanocatalyzers are released and able to access to the endogenous H2 O2 , exerting the improved Fenton-like reaction within the more acidic condition. Finally, such smart nanoplatform enables self-boosting generation of reactive oxygen species (ROS) and induces strong intracellular oxidative stress, leading to the substantial anticancer outcomes in vivo, which may provide a new insight for tumor-specific cascade catalytic therapy and reducing the "off-target" toxicity to surrounding normal tissues.

As a unique natural satellite of the Earth, the Moon has always attracted much attention, and one subject of interest is the establishment of an Earth observation platform on the Moon. Compared with the existing spaceborne and airborne observation platforms, a Moon-based Earth observation platform would have the unique advantage of the ability to obtain global and large-scale observation data. At present, the study on Moon-based Earth observations is in theory, so it is necessary to use simulation methods to understand the observation performance of a Moon-based Earth observation platform. In this study, a method for Moon-based Earth observation imaging simulation in the thermal infrared band is developed to study the Moon-based thermal infrared imaging process. The method comprises three parts, including the estimation of Moon-based imaging coverage, the acquisition of the radiation intensity at the entrance pupil, and the simulated image output from the Moon-based thermal infrared sensor. Then, the simulated results are validated with the existing spaceborne observation data. Results show that the absolute error of Moon-based thermal infrared simulations is between 1.3–5.7 K, the RMSE is between 1.38 – 3.12 K, and the relative error is between 0.44% – 2.12%, indicating that the thermal infrared imaging model can more realistically simulate the true conditions of ground surface and that a Moon-based Earth observation platform could observe the Earth in the thermal infrared band.

Resonance of both subthreshold and suprathreshold membrane potentials has been found in brain or motor neurons involving in the information processing or locomotion control via frequency response, which is mainly related to the hyperpolarization-activated cation current ( $$I_{{\text {h}}}$$ ). In the present paper, the modulations of $$I_{{\text {h}}}$$ current on resonance are acquired in a bursting neuron model, which closely match experimental observations. Firstly, the increase of $$I_{{\text {h}}}$$ current induces stable node changed to stable focus related to Hopf bifurcation, and to bursting via complex bifurcations including the big homoclinic orbit related to type I excitability. Secondly, the subthreshold resonance can be evoked by small stimulation from focus instead of node, resembling the experimental observation that subthreshold resonance appears at strong ( $$I_{{\text {h}}}$$ ) current. Thirdly, the modulation regularity of $$I_{{\text {h}}}$$ current on frequency and amplitude of resonance is simulated, closely matching the experimental observations, which can be well explained with the changing trends of imaginary and real part of eigenvalues of the focus. Last, the suprathreshold bursting is induced by strong stimulation from the stable focus near big homoclinic orbit, resembling that observed in the experiment. The bursting exhibits “suprathreshold resonance” similar to those evoked near Hopf bifurcation corresponding to type II excitability. A novel condition for “suprathreshold resonance” and the underlying codimension-2 bifurcations are acquired. The results present the comprehensive viewpoints on the subthreshold resonance and extend the condition for the “suprathreshold resonance”, which are helpful for deep understanding resonance in the brain or motor neurons with $$I_{{\text {h}}}$$ current.

Flexible thermoelectric materials and devices have gained wide attention due to their capability to stably and directly convert body heat or industrial waste heat into electric energy. Many research and synthetic methods of flexible high-performance p-type thermoelectric materials have made great progress. However, their counterpart flexible n-type organic thermoelectric materials are seldom studied due to the complex synthesis of conductive polymer and poor stability of n-type materials. In this work, bismuth tellurium (Bi2Te3) nanosheets are in situ grown on single-walled carbon nanotubes (SWCNTs) assisted by poly(vinylpyrrolidone) (PVP). A series of flexible SWCNTs@Bi2Te3 composite films on poly(vinylidene fluoride) (PVDF) membranes are obtained by vacuum-assisted filtration. The high electrical conductivity of 253.9 S/cm, and a corresponding power factor (PF) of 57.8 μW/m·K2 is obtained at 386 K for SWCNTs@Bi2Te3-0.8 film. Moreover, high electrical conductivity retention of 90% can be maintained after a 300-cycle bending test and no obvious attenuation can be detected after being stored in an Ar atmosphere for 9 months, which exhibits good flexibility and excellent stability of the SWCNTs@Bi2Te3 composite films. This work shows a convenient method to fabricate n-type and flexible thermoelectric composite film and further promotes the practical application of n-type flexible thermoelectric materials.

High-entropy oxides (HEOs) are a new class of materials that are promising for a wide range of applications. Designing HEOs needs to consider both geometric compatibility and electrical equilibrium. However, there is currently no available method to systematically consider these two factors when selecting constituent materials for making HEOs. Here we propose a two-step strategy, where a HEO system to be explored is first partitioned into multiple subsystems based on the valence combinations of substituted cations; the geometric compatibility is then considered in selecting suitable substituted cations. We demonstrate this strategy by using A(5B0.2)O3 perovskite as a model system. We show that the system can be partitioned into 12 subsystems. Ten of the subsystems have formed a single-phase cubic perovskite, while two have partially ordering structure. The formation of single phases is correlated to Goldschmidt's tolerance factor, while the formation of the ordering structure is mainly correlated to cation-valence difference. We anticipate that this strategy is applicable to exploring HEOs in other systems.

The fixation of the catalyst interface is an important consideration for the design of practical applications. However, the electronic structure of MoS2 is sensitive to its embedding environment, and the catalytic performance of MoS2 catalysts may be altered significantly by the type of binding agents and interfacial structure. Interfacial engineering is an effective method for designing efficient catalysts, arising from the close contact between different components, which facilitates charge transfer and strong electronic interactions. Here, we have developed a layer-by-layer (LbL) strategy for the preparation of interfacial MoS2-based catalyst structures with two types of conducting polymers on various substrates. We demonstrate how the assembled partners in the LbL structure can significantly impact the electronic structures in MoS2. As the number of bilayers grows, using polypyrrole as a binder remarkably increases the catalytic efficacy as compared to using polyaniline. On the one hand, the ratio of S22- (or S2-), which is related to the remaining active hydrogen evolution reaction (HER) species, is further increased. On the other hand, density functional theory calculations indicate that the interfacial charge transport from the conducting polymers to MoS2 may boost the HER activity of the interfacial structure of the conducting polymer/MoS2 by decreasing the adsorption free energy of the intermediate H* at the S sites in the basal plane of MoS2. The optimized catalytic efficacy of the (conducting polymer/MoS2)n assembly peaks is obtained with 16 assembly cycles. In preparing interfacial catalytic structures, the LbL-based strategy exhibits several key advantages, including the flexibility of choosing assembly partners, the ability to fine-tune the structures with precision at the nanometer scale, and planar homogeneity at the centimeter scale. We expect that this LbL-based catalyst immobilization strategy will contribute to the fundamental understanding of the scalability and control of highly efficient electrocatalysts at the interface for practical applications.

We report the first example of in situ polymer brush growth on the surface of upconversion nanoparticles (UCNPs) in a one-pot near-infrared (NIR) light mediated reversible addition–fragmentation chain transfer (RAFT) polymerization. In the process of polymerization, the surface growth of polymer brushes was realized through an efficient in situ ligand exchange between a photo-activated chain transfer agent (CTA) and the ligand groups on the surface of UCNPs. BF4− was found to be the most efficient ligand in comparison with oleic acid and pyridine. The 980 nm NIR-mediated RAFT polymerization exhibits good temporal control with a low dispersity (Mw/Mn < 1.30), and the thickness of the polymer brushes can be easily adjusted by changing the polymer molecular weight and light exposure time. Moreover, the growth of polymer brushes can proceed even if there is a barrier (e.g. chicken skin) outside the reactor due to the excellent penetration ability of the NIR light.

A new multi-objective optimized bacterial foraging algorithm - Hybrid Multi-Objective Optimized Bacterial Foraging Algorithm (HMOBFA) is presented in this article. The proposed algorithm combines the crossover-archives strategy and the life-cycle optimization strategy, look for the best method through research area. The crossover-archive strategy with an external archive and internal archive is assigned to different selection principles to focus on diversity and convergence separately. Additionally, according to the local landscape to satisfy population diversity and variability as well as avoiding redundant local searches, individuals can switch their states periodically throughout the colony lifecycle with the life-cycle optimization strategy. all of which may perform significantly well. The performance of the algorithm was examined with several standard criterion functions and compared with other classical multi-objective majorization methods. The examiner results show that the HMOBFA algorithm can achieve a significant enhancement in performance compare with other method and handles many-objective issues with solid complexity, convergence as well as diversity. The HMOBFA algorithm has been proven to be an excellent alternative to past methods for solving the improvement of many-objective problems.

Simultaneous measurement of the substrate/film thickness and film conductivity in a thin metal film/substrate structure is still challenging. In this article, we propose a method for the measurement based on a terahertz time-domain spectroscopy system by combining time-domain and frequency-domain analysis, in which an error function is established, whereas quasi-Newton algorithm is employed. The advantage of the proposed method is that neither the substrate thickness nor the terahertz transmission of the bare substrate is prerequisite before the measurement. The feasibility of the method is validated by our experimental conclusion that agrees well with the theoretical model.

Carbon surfaces become significantly activated with plasma treatment enhancing the surface energy, wettability, and bio-conjugation. However, the activated surfaces are influenced by aging effect or reorientation phenomenon, a rarely reported occurrence, that refers to the loss of surface activity with time. Generated plasma-activated surface functional groups suffer from a brief shelf life as they reorient themselves to occupy lower states of energy. This study thoroughly assesses plasma-treated pyrolyzed carbon platforms with O2, N2, and Ar plasma radiations over 3 weeks. Pristine, immediately treated, and aged carbon samples were analyzed by SEM, AFM, WCA, and XPS to observe physical and chemical changes of the surfaces. Moreover, the electrochemical analyses demonstrated radical alterations of the surface characteristics immediately after the treatment; an activation which did not last long regardless of the plasma choice. With time, clear signs of surface inactivation were recorded manifesting in the form of decreased roughness, increased water contact angle, and major alterations of surface chemical composition, capacitance, and resistance. Our observations confirm that the plasma-treated carbon samples return to the pristine surface characteristics within a brief period of time thus demonstrating the loss of surface activity irrespective of the treatment choice.

Significance Donald Trump's 2016 victory in the Electoral College without leading in the popular vote has led to speculation of a repeat in 2020. If the Democrats were to win the popular vote but by less than a landslide, could they be thwarted from stopping Trump once again? We examine how Electoral College outcomes are conditioned by how states had voted in previous elections. Our simulations suggest that in 2020, the Electoral College bias is likely to again favor the Republicans. However, the expectation is less distortion of the popular will than in 2016. There is even the possibility that if Trump was to win the 2020 popular vote by a slim margin, it could be he who loses the Electoral College., Donald Trump’s 2016 win despite failing to carry the popular vote has raised concern that 2020 would also see a mismatch between the winner of the popular vote and the winner of the Electoral College. This paper shows how to forecast the electoral vote in 2020 taking into account the unknown popular vote and the configuration of state voting in 2016. We note that 2016 was a statistical outlier. The potential Electoral College bias was slimmer in the past and not always favoring the Republican candidate. We show that in past presidential elections, difference among states in their presidential voting is solely a function of the states’ most recent presidential voting (plus new shocks); earlier history does not matter. Based on thousands of simulations, our research suggests that the bias in 2020 probably will favor Trump again but to a lesser degree than in 2016. The range of possible outcomes is sufficiently wide, however, to even include some possibility that Joseph Biden could win in the Electoral College while barely losing the popular vote.

Bisimulation is a concept that captures behavioural equivalence of states in a transition system. In [Linan Chen, Florence Clerc, and Prakash Panangaden, Bisimulation for feller-dynkin processes, in: Proceedings of the Thirty-Fifth Conference on the Mathematical Foundations of Programming Semantics, Electronic Notes in Theoretical Computer Science 347 (2019) 45–63.], we proposed two equivalent definitions of bisimulation on continuous-time stochastic processes where the evolution is a flow through time. In the present paper, we develop the theory further: we introduce different concepts that correspond to different behavioural equivalences and compare them to bisimulation. In particular, we study the relation between bisimulation and symmetry groups of the dynamics. We also provide a game interpretation for two of the behavioural equivalences. We then compare those notions to their discrete-time analogues.

Abiotic stresses affect the plant growth in different ways and at different developmental stages that reduce the crop yields. The increasing world population continually demands more crop yields; therefore it is important to use low-cost technologies against abiotic stresses to increase crop productivity. Soil microorganisms survive in the soil associated with plants in extreme condition. It was demonstrated that these beneficial microorganisms promote plant growth and development under various stresses. The soil microbes interact with the plant through rhizospheric or endophytic association and promote the plant growth through different processes such as nutrients mobilization, disease suppression, and hormone secretions. The microorganisms colonized in the rhizospheric region and imparted the abiotic stress tolerance by producing 1-aminocyclopropane-1- carboxylate (ACC) deaminase, antioxidant, and volatile compounds, inducing the accumulation of osmolytes, production of exopolysaccharide, upregulation or downregulation of stress genes, phytohormones and change the root morphology. A large number of these rhizosphere microorganisms are now patented. In the present review, an attempt was made to throw light on the mechanism of micro-organism that operates during abiotic stresses and promotes plant survival and productivity.

Aiming at the control problem for the speed regulation system of permanent magnet synchronous motor (PMSM), an integral fixed-time sliding mode control algorithm with the disturbance estimation compensation is designed to improve PMSM system’s disturbance rejection ability in this paper. First of all, the integral fixed-time sliding mode surface is selected according to the error dynamical equation. Then an integral fixed-time sliding mode control algorithm is proposed and rigorous analysis method of the Lyapunov function is provided to demonstrate the speed tracking error will converge to zero in a fixed time. Besides, considering the effect of disturbance load torque, an integral fixed-time sliding mode control algorithm with disturbance estimation compensation is proposed. Through disturbance feedforward compensation, the integral fixed-time sliding mode control law can offer a better dynamical performance with smaller value for the speed chattering. Finally, comparison results of numerical experiments are provided to verify the effectiveness and superiority of the integral fixed-time sliding mode control method.

The shape of a plasmonic nanoparticle strongly controls its light-matter interaction, which in turn affects how specific morphologies may be used in applications such as sensing, photodetection, and active pixel displays. Here, we show that particle shape also controls plasmonic photocatalytic activity. Three different Al nanocrystal morphologies, octopods, nanocubes, and nanocrystals, all with very similar plasmon resonance frequencies, were used as photocatalysts for the H

In this study, powder mixtures at atomic ratios suitable for formation of Sr(Ti0.2Y0.2Zr0.2Sn0.2Hf0.2)O3-x were flash sintered at 1000 °C and 40 mA/mm2. X-ray diffraction and energy-dispersive spectroscopy analyses revealed the formation of single-phase oxides after sintering for 1 min. This rapid formation of single-phase oxide was attributed to flash sintering characteristics, which not only enhanced the diffusion rate, but also softened the lattice. Compared to conventional heat treatment sintering, the sintering time was shortened to 1 min from 10 h, while the sample temperature was reduced to 1314 from 1500 °C. Therefore, flash sintering is a promising technique for rapid synthesis of high-entropy oxides.

Saccharina japonica is a brown macroalga that has been commercially cultivated in China for almost a century. As a natural raw material, it is widely used in the food and pharmaceutical industries, and it may potentially be useful for biofuel production. However, little is known about the genes involved in carbohydrate biosynthesis, and their regulation is less understood. In this study, the analysis of growth traits and alginate and mannitol contents suggested that sporophyte development could be divided into four stages. Accordingly, we performed transcriptome analysis of the S. japonica sporophyte. In total, 589 million clean reads were generated, and 4,514 novel genes were identified. Gene expression analysis revealed that 2,542 genes were differentially expressed. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that these genes were significantly enriched in "Carbon metabolism," "Photosynthesis," and "Photosynthesis-antenna proteins" pathways, which are important for metabolism of various carbohydrates during sporophyte development. Systematic analysis identified the genes encoding enzymes for the biosynthesis of cell wall carbohydrates (including alginate, fucoidan, and cellulose) and cytoplasm storage carbohydrates (mannitol, laminarin, and trehalose). Among them, some key genes associated with carbohydrate content were further identified based on detailed expression profiling, representing good candidates for further functional studies. This study provides a global view of the carbohydrate metabolism process and an important resource for functional genomics studies in S. japonica. The results obtained lay the basis for elucidating the molecular mechanism of carbohydrate biosynthesis and for genetic breeding of carbohydrates-related traits in kelp.

Coherence resonance (CR), which is typical nonlinear phenomenon that noise plays construct roles, has been widely investigated in single neurons at resting state instead of bursting behavior when noise free. In the present paper, multiple CRs evoked from bursting instead of resting state and the underlying bifurcation mechanism are studied in a theoretical neuron model composed of fast subsystem and slow variable, which is very important for the bursting neurons receiving strong synaptic noise in the central nervous system. With increasing noise intensity within a range, the bursting period decreases to induce the burst number increases firstly and then becomes irregular, which results in the increase firstly and then decrease in the corresponding peak of the power spectrum of membrane potentials, i.e., CR is evoked from bursting instead of resting state. With further increasing noise intensity, two other peaks exhibit CR phenomenon, one at middle frequency and middle noise intensity and the other at large frequency and strong noise intensity, which shows that multiple CRs are evoked from bursting. Furthermore, the bifurcation mechanism of the latter two resonant peaks is acquired with fast–slow variable dissection method. With increasing the value of slow variable, the fast subsystem exhibits a fold bifurcation of limit cycle and a subcritical Hopf bifurcation to a stable focus, and the imaginary part of the characteristic value of the focus increases, which implies that spikes evoked from the focus exhibit increasing frequency. The trajectory of the deterministic bursting in phase space locates between the two bifurcations and alternates between the coexisting limit cycle and focus of the fast subsystem. With increasing noise intensity, the value of slow variable of the stochastic bursting increases and moves to a range of the focus of the fast subsystem, and the spikes of the stochastic bursting are evoked from the focus by noise. Therefore, the stronger the noise intensity, the larger the value of slow variable, and the higher frequency the spikes, due to the changes of characteristic values, which is the cause that the peaks with middle and high frequency appear at middle and strong noise intensity, respectively. The results of the present paper extend the concept of CR to multiple CRs evoked from bursting, provide the bifurcation mechanism underlying the multiple CRs, and imply multiple chances to utilize noise to enhance information of bursting neurons.

We consider the Voronoi diagram generated by $n$ i.i.d. $\mathbb{R}^{d}$-valued random variables with an arbitrary underlying probability density function $f$ on $\mathbb{R}^{d}$, and analyse the asymptotic behaviours of certain geometric properties, such as the measure, of the Voronoi cells as $n$ tends to infinity. We adapt the methods used by Devroye et al (2017) to conduct a study of the asymptotic properties of two types of Voronoi cells: 1, Voronoi cells that have a fixed nucleus; 2, Voronoi cells that contain a fixed point. For the first type of Voronoi cells, we show that their geometric properties resemble those in the case when the Voronoi diagram is generated by a homogeneous Poisson point process. For the second type of Voronoi cells, we determine the limiting distribution, which is universal in all choices of $f$, of the rescaled measure of the cells. For both types, we establish the asymptotic independence of measures of disjoint cells., Comment: 31 papges, 4 figures

Zirconia ceramics were prepared by oscillatory pressure sintering (OPS) and hot pressing (HP). The result revealed that OPS could enhance densification compared to HP when sintering temperature was higher than a critical value. The onset temperature for rapid grain growth was found to be same for both techniques. However, rate of grain growth in OPS was lower than that in HP. Furthermore, the result also showed that samples prepared by OPS exhibited higher hardness than those prepared by HP when sintering temperature was higher than the critical value. The improved hardness was solely due to the higher density of the samples prepared by OPS.

Five-component entropy-stabilized oxide ceramic (Mg0.2Ni0.2Co0.2Cu0.2Zn0.2O) has been successfully synthesized by reaction assisted flash sintering at room temperature. Compared to the conventional sintering technique, the starting materials have been completely transformed to a single rocksalt phase in just a few seconds. Analysis suggests that the electric field significantly accelerated the rate of phase transition. These results clearly demonstrate the feasibility of employing the reaction assisted flash sintering technique to fabricate entropy-stabilized oxides with new chemistries and attractive properties.

WC-Fe-Ni cemented carbide was prepared by oscillatory pressure sintering (OPS) technique for the first time. Compared to HP, OPS can significantly improve densification and suppress grain growth of the material. The samples prepared by OPS exhibited higher hardness. The highest hardness obtained is > 19 GPa, much higher than those ever reported for the similar materials. The improvements in sintering and mechanical properties are likely due to that the oscillatory pressure enhanced particle rearrangement and plastic flow of the liquid binder phase, as well as generated defects. The results suggest that OPS is a very promising technique for preparing high performance cemented carbides.

Over the recent 20 years, numerous researches have focused on the lithium-ion batteries anodes of MOx 3d-metal oxides which have a high specific capacity. For example, the specific capacity of CuO material as an anode is ∼670 mAh g−1. Unfortunately, serious capacity degradation limits their promising applicability. To improve cyclic stability, PPy is covered on CuO surface to prepare CuO@PPy core–shell hybrid materials by chemical polymerisation. Pyrrole amount plays an important role on control the PPy shell thickness. After PPy coating, the lithium-ion battery cycling stability and coulombic efficiency have been improved greatly, and CP-5 sample has the best cyclic stability and coulombic efficiency. The capacity retention of bare CuO is only 27.9% after 200 cycles. By contrast, the capacity retention of CP-5 sample is ∼100%. The flexible conducting polymers shell (PPy) lead to improved cyclic stability. These results give a strategy to solve MOx 3d-metal oxide capacity degradation as Lithium-ion batteries anode.

Heterogeneous magnesium matrix nanocomposites (Hetero-Mg-NCs) exhibited excellent strength-toughness synergy, but their damage behavior and toughness mechanism lacked of investigation. Here, atomic force microscopy was first employed to characterize the microstructure evolution and damage behavior of the Hetero-Mg-NCs after indentation. The heterogeneous structure comprised of pure Mg areas (soft phase) and Mg nanocomposite areas (hard phase) was revealed by the electrostatic force microscopy. Furthermore, the surface morphology and cracks of the deformed area were investigated with high resolution. The results indicated the soft phase undertook most of the deformation and played an important role in capturing and blunting the crack.

Carbon nanotubes (CNTs) as superior support materials for functional nanoparticles (NPs) have been widely demonstrated. Nevertheless, the homogeneous loading of these NPs is still frustrated due to the inert surface of CNTs. In this work, a facile gas-phase pyrolysis strategy that the mixture of ferrocene and CNTs are confined in an isolated reactor with rising temperature is developed to fabricate a carbon-coated Fe3O4 nanoparticle/carbon nanotube (Fe3O4@C/CNT) composite. It is found the ultra-small Fe3O4 NPs (

Pseudo-reservoir stimulation in horizontal well is an effective technique for indirectly extracting coalbed methane (CBM) in soft coal from the surrounding rocks (pseudo-reservoir). However, systematic studies of the theory and on-site application of this technique are still lacking, which severely hinders its application. In this paper, the technical principles of pseudo-reservoir stimulation are analyzed firstly, and then, the technical advantages are demonstrated by experimental tests and theoretical analysis. The results show that the pseudo-reservoir generally possesses considerable gas adsorption capacity, with the gas content of 1.56–4.22 cm3/g (avg. 2.51 cm3/g) in Well XC-01, which can be extracted as supplementary resources. The fracability of the pseudo-reservoirs is 0.73–0.92, which is much higher than that of the coal seam, i.e., 0.03–0.43. Meanwhile, the compressive and tensile strength and cohesion of the pseudo-reservoir are higher than those of the coal seam, indicating pseudo-reservoir stimulation is more conducive to forming fracture network, and maintaining wellbore stability and fracture conductivity. The technical feasibility of pseudo-reservoir stimulation is determined by the regional geological conditions, showing simple tectonic conditions and well-developed surrounding rocks with high fracability and mechanical strength but low permeability, water sensitivity and water content are beneficial for the technique application. Note that the fracture conductivity in pseudo-reservoir is more stable and higher than that in coal seam, pseudo-reservoir stimulation is beneficial for the CBM extraction from both hard and soft coal seams. By minimizing the gas diffusion distance, this technique overcomes the technical obstacles to the CBM commercialized production in soft coal.

Bubbles are ubiquitous in the natural environment, where different substances and phases of the same substance forms globules due to differences in pressure and surface tension. Total internal reflection occurs at the interface of a bubble, where light travels from the higher refractive index material outside a bubble to the lower index material inside a bubble at appropriate angles of incidence, which can lead to a phase shift in the reflected light. Linearly polarized skylight can be converted to elliptically polarized light with efficiency up to 53% by single scattering from the water-air interface. Total internal reflection from air bubble in water is one of the few sources of elliptical polarization in the natural world. Stationary and dynamic scenes of air bubbles in water in both indoor and outdoor settings are studied using an imaging polarimeter. Our results are important for studies in fluid dynamics, remote sensing, and polarimetry.

For organnoboron compounds, the substituents on boron atoms are very important because they not only impact on the molecular stability but also significantly modulate the electronic structures and properties. In this manuscript, we synthesized two new B⟵N-containing azaacenes with propynyl groups on boron atoms through one-step Grignard reaction. Replacing fluorine atoms by propynyl groups greatly impacts on the electronic energy levels, especially enhancing the HOMO levels, thus leading to the narrowed HOMO-LUMO bandgaps. These B⟵N-containing azaacenes exhibit the NIR light-absorption (λabs = 706 nm for 2a and 762 nm for 2b) and fluorescence properties (λem = 740 nm for 2a and 802 nm for 2b), as well as multiple reversible redox behaviors, which are significantly different from the analogs with fluorine atoms. This study thus provides a functional substituent of boron atom, which may lead to new organoboron materials with fascinating properties.

We developed a series of Fe doping in Co-based perovskites SrTi0.1CoxFe0.9-xO3-δ (x = 0.5, 0.6, 0.7, 0.9) to investigate their OER activity and stability in alkaline media. Among all the samples, SrTi0·1Co0·5Fe0·4O3-δ (donated as STCF-154) shows wonderful OER activity with an overpotential of 0.37 V, a current density of 33.65 mA cm−2 at 1.71 V, and a Tafel slope of 94.82 mV dec−1. Besides, the potential of STCF-154 remained nearly unchanged for at least 8 h at a fixed current density of 10 mA cm−2disk on GC electrode. The improved activity and stability are likely originating from the highly oxidative oxygen species O22−/O− formed in STCf-154, which can easily migrate from bulk STCF-154 and “spillover” to the surface of the catalyst during OER process. The Fe doping in Co-based perovskites had synergetically enhanced activity and can be considered as a good candidate for the OER in alkaline solution.

The electric conductivity of zirconia in the steady stage of flash sintering is measured under various current densities. We find that the steady stage conductivity ( σ s ) is higher than the normal conductivity ( σ n ) measured at non-flashing conditions, even Joule heat is considered. The higher conductivity is ascribed to the increase in charge carrier concentration. The difference between σ s and σ n is then used to estimate the oxygen vacancy concentration. It is found that the concentration increases with increasing current density at beginning and then decreases with further increasing current density. A speculative explanation is proposed to account for this phenomenon.

Assessment of groundwater vulnerability to contamination plays a vital role in the utilization and protection of groundwater resource. In this study, a vulnerability map for Boracay Island, Philippines was developed using a modified self-organizing map algorithm to determine groundwater vulnerability in light of massive tourism developments in the island. Self-organizing map using the Nguyen-Widrow initialization algorithm was used to cluster DRASTIC data which were pre-processed using data cleaning normalization schemes. The vulnerability map developed showed that groundwater resource in the island is susceptible to contamination as confirmed by groundwater quality analysis. The result of the study demonstrates the effectiveness of the improved SOM algorithm as a tool for assessment of groundwater vulnerability and is comparable with the traditional DRASTIC method. The developed methodology allows grouping of datasets into clusters that represent the level of vulnerability to contamination of the groundwater. Further, this approach can be applied to other islands to ensure the balance between tourism developments and ecological integrity of the scarce groundwater resource.

Nanosheet-constructed porous CoMoS4 arrays are grown on 3D self-supported Ni foam by a simple solvothermal strategy. The resulting sample can be immediately served as an adhesive-free electrode of supercapacitors. Surprisingly, the obtained CoMoS4/Ni foam with high chemical activity and unique structure exhibits excellent performance including the high specific capacity of 276 mAh/g at 0.25 A/g. Moreover, the prepared CoMoS4/Ni foam and commercial activated carbon (AC) are specified as the positive/negative electrodes of a hybrid supercapacitor. The assembled CoMoS4/Ni foam//AC hybrid device outputs a high specific energy of 58 Wh/kg at a specific power of 328 W/kg, and 95% of initial capacity after 10,000 charge-discharge cycles. These conditions are favorable for the practical application of the prepared CoMoS4/Ni foam. Therefore, the nanosheet-constructed porous CoMoS4 arrays on Ni foam can be considered as a hopeful electrode for energy storage devices.

Gallium oxide (Ga2O3) films have been deposited on SrTiO3 (100) substrates by using the metal-organic chemical vapor deposition (MOCVD) method. Post-deposition annealing was performed at different temperatures. XRD θ-2θ scans displayed that the annealing at 1000 °C leaded to β phase Ga2O3 film with the best crystalline quality. Microstructural and chemical composition analyses revealed that this film was single crystal β-Ga2O3 with stoichiometric ratio. The epitaxial relationships were clearly determined as β-Ga2O3 (100) || SrTiO3 (100) with β-Ga2O3 [001] || SrTiO3 . All of the prepared Ga2O3 samples have average transmittances in the visible range of more than 70%.

International audience; The aim of molecular electronics is to miniaturize active electronic devices and ultimately construct single-molecule nanocircuits using molecules with diverse structures featuring various functions, which is extremely challenging. Here, we realize a gate-controlled rectifying function (the on/off ratio reaches ∼60) and a high-performance field effect (maximum on/off ratio >100) simultaneously in an initially symmetric single-molecule photoswitch comprising a dinuclear ruthenium-diarylethene (Ru-DAE) complex sandwiched covalently between graphene electrodes. Both experimental and theoretical results consistently demonstrate that the initially degenerated frontier molecular orbitals localized at each Ru fragment in the open-ring Ru-DAE molecule can be tuned separately and shift asymmetrically under gate electric fields. This symmetric orbital shifting (AOS) lifts the degeneracy and breaks the molecular symmetry, which is not only essential to achieve a diode-like behavior with tunable rectification ratio and controlled polarity, but also enhances the field-effect on/off ratio at the rectification direction. In addition, this gate-controlled symmetry-breaking effect can be switched on/off by isomerizing the DAE unit between its open-ring and closed-ring forms with light stimulus. This new scheme offers a general and efficient strategy to build high-performance multifunctional molecular nanocircuits.

Syngas, an extremely important chemical feedstock composed of carbon monoxide and hydrogen, can be generated through methane (CH4) dry reforming with CO2. However, traditional thermocatalytic processes require high temperatures and suffer from coke-induced instability. Here, we report a plasmonic photocatalyst consisting of a Cu nanoparticle ‘antenna’ with single-Ru atomic ‘reactor’ sites on the nanoparticle surface, ideal for low-temperature, light-driven methane dry reforming. This catalyst provides high light energy efficiency when illuminated at room temperature. In contrast to thermocatalysis, long-term stability (50 h) and high selectivity (>99%) were achieved in photocatalysis. We propose that light-excited hot carriers, together with single-atom active sites, cause the observed performance. Quantum mechanical modelling suggests that single-atom doping of Ru on the Cu(111) surface, coupled with excited-state activation, results in a substantial reduction in the barrier for CH4 activation. This photocatalyst design could be relevant for future energy-efficient industrial processes. Syngas is a mixture of CO and H2 that can be converted into a variety of fuels. Syngas can be produced thermocatalytically from CH4 and CO2, but this requires high temperatures and coke formation can be a problem. Here the authors demonstrate lower temperature, light-driven production of syngas using a coke-resistant plasmonic photocatalyst.

A three-dimensional model for fabrication process of Ag2Ga nanoneedle based on phase field model has been performed. With the development of model, the fabrication of Ag2Ga nanoneedle which...

Cloud Manufacturing Service Composition (CMSC) is the key issue and taking an important role in solving the interconnection and interoperability of resources and services for Cloud Manufacturing (CMfg). CMSC is a typical kind of NP-hard problems with the characteristics of dynamic and uncertainty. Solving large scale CMSC problem by using the traditional methods might be not efficient because of the massive complex resources and large-scale searching space. To overcome this shortcoming, a novel artificial bee colony algorithm named Multiple Improvement Strategies based Artificial Bee Colony algorithm (MISABC) is proposed. MISABC improves the performance of classical ABC algorithm through several strategies such as (a) differential evolution strategy (DES), (b) oscillation strategy with classical trigonometric factor (TFOS), (c) different dimensional variation learning strategy (DDVLS), (d) Gaussian distribution strategy (GDS). Meanwhile, to address the CMfg scenario, we also propose a manufacturing service composition scheme named as Multi-Module Subtasks Collaborative Execution for Cloud Manufacturing Service Composition (MMSCE-CMSC). Eight benchmark functions with different characteristics, a comparison study with existed improved ABC algorithms and a case study are used to validate the performance of the algorithm. The results demonstrate the effectiveness of the proposed method for addressing complex CMSC problem in CMfg.

Lake ice phenology is a sensitive indicator reflecting global warming. In this article, the long-term changes in lake ice phenology of the second-largest lake at Tibetan Plateau (i.e., the Nam Co) in response to climate change are investigated based on mathematical modeling. The model has been testified capable of reproducing daily surface temperature of the lake in both frozen and unfrozen seasons. The lake ice phenology determined according to the simulated lake surface temperature is found consistent with that derived from satellite observations. For the Nam Co during the period 1978–2017, the freezing date has been delayed (reached up to 0.57 days/year), whereas the thawing date became earlier (−0.23 days/year). The trend of lake ice phenology is significantly correlated to the annual minimal lake surface and air temperature. Modeling experiment suggests that lake ice phenology of the Nam Co is very sensitive to a warmer climate. Under warmer future, much later freezing date and earlier thawing date are expected; hence the ice-covering duration would be significantly shortened.

Land surface temperature (LST) is a key parameter and plays an important role in hydrology, ecology, environment, and biogeochemistry. It is difficult for the existing satellites to acquire global LST with spatial and temporal consistency. The Moon-based Earth observation platform with a long life, large coverage can observe continuously the Earth, and obtain the global-scale LST. At present, various approaches for retrieving LST from passive microwave remote sensing data have been developed for the satellite remote sensing data with small and constant viewing zenith angle, however, the Moon-based Earth observation platform located outside the Earth's ionosphere has the viewing zenith angle of 0-90°. In this study, a modified physical-based method of LST retrieval from passive microwave data was developed for wide viewing zenith angles, and the LST and emissivity can be simultaneously estimated through the analysis of various atmospheric and ionosphere parameters. Three types of data, including the FengYun-3B satellite microwave radiation imager data, the multichannel Advanced Microwave Scanning Radiometer data, and Moon-based microwave radiation simulation data with the viewing zenith angles of 52-53°, 55°, and 0-90°, respectively, were used to retrieve LST. Results show that the estimation accuracy of LST decreases with the increase of viewing zenith angle. The 23.8 and 36.5 GHz brightness temperature is optimum for the LST estimation under a large-scale viewing zenith angle, and the root mean square errors of the LST are 5.18, 5.44, and 4.79 K, respectively.

Excitonic states of a many-electron system in phosphorene quantum dots (PQDs) are investigated theoretically by using a configuration interaction approach. For a triangular PQD in various dielectric environments, its exciton is found to obey two distinct scaling rules. When there is a strong screening effect present in the nanodot, the exciton binding energy (Δex) is shown to be around -150 meV as the long-range Coulomb interactions are totally suppressed and it increases to about 100 meV when the effective dielectric constant (εr) decreases to 12.5. Over this range of εr, Δex is found to be well fitted into a quadratic form of εr-1, which scales neither linearly with εr-2 like the case of bulk three-dimensional semiconductors nor linearly with εr-1 like the case previously reported for graphene nanostructures. When εr is reduced below 10.0, however, Δex is shown to exhibit a perfect linear relationship with εr-1, which behaves just like that of a two-dimensional graphene sheet. On the other hand, with the reduced εr, the quasiparticle gap is found to decrease instead of increasing like in most of the semiconductor nanostructures. As a result, it is revealed that the relationship of Δex with the quasi-particle gap deviates largely from the linear one previously reported for graphene and many other two-dimensional materials.