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In this article, a global finite-time active disturbance rejection control (ADRC) scheme is proposed for tracking control of redundant parallel manipulators with unknown bounded uncertainties. This approach combines an ADRC and a global finite-time control for high accuracy trajectory tracking control. Based on the nonsingular fast terminal sliding mode control, the proposed approach can remove the condition in the original ADRC that the derivative of the uncertainties is required to be bounded. The extended state observer is employed to handle the real-time estimation of the total uncertainty. It can be found that the proposed scheme not only can converge fast to the semi-global finite-time stable equilibrium but also can have superior tracking control performance. In summary, compared to existing approaches, the proposed scheme can have several advantages, such as uncertainty rejection, easy implementation, robustness, chattering-free, high precision, and no need for prior knowledge of bounded uncertainties. The simulation results validate the effectiveness of the proposed method.

The widespread applications of aggregation-induced emission luminogens (AIEgens) inspire the creation of AIEgens with novel structures and functionalities. In this work, we focused on the direct and efficient synthesis of a new type of AIEgens, imidazo[1,5-a]pyridicne derivatives, via iodine mediated cascade oxidative Csp2–H or Csp–H amination route from phenylacetylene or styrenes under mild conditions. The resulted compounds showed excellent AIE characteristics with tunable maximum emissions, attractive bioimaging performance, and potential anti-inflammatory activity, which exert broad application prospects in material, biology, medicine, and other relevant areas.

Despite the intriguing merits of lithium-sulfur (Li-S) systems, they still suffer from the notorious “shuttling-effect” of polysulfides. Herein, carbon materials with rational tailoring of morphology and pores were designed for strong loading/adsorption with the controlling of energy-storage ability. Through rational tailoring, it is strongly verified that such engineering of evolutions result in variational of sulfur immobilization in the obtained carbon. As expected, the targeted sample delivers a stable capacity of 925 mAh g−1 after 100 loops. Supporting by the “cutting-off” manners, it is disclosed that mesopores in carbon possess more fascinated traits than micro/macropores in improving the utilization of sulfur and restraining Li2Sx (4 ≤ x ≤ 8). Moreover, the long-chain polysulfide could be further consolidated by auto-doping oxygen groups. Supported by in-depth kinetic analysis, it is confirmed that the kinetics of ion/e- transfer during charging and discharging could be accelerated by mesopores, especially in stages of the formation of solid S8 and Li2S, further improving the capacity of ion-storage in Li-S battery. Given this, the elaborate study provide significant insights into the effect of pore structure on kinetic performance about Li-storage behaviors in Li-S battery, and give guidance for improving sulfur immobilization.

Ultra-high temperature ceramic-modified C/C composites (C/C-UHTCs) were prepared by the reactive infiltration of K2MeF6 (Me = Zr, Ti) mixed with Si and Zr-Si powders. Molten salt infiltration can be divided into two stages: salt ion melt and Me-Si alloy melt. In the temperature range below 1400 °C, Zr and Si dissolve in the molten salt, are carried by the ion melt, and precipitate at the PyC interface to form carbides. Above 1400 °C, a large amount of molten salt volatilises and thermally decomposes. The Me-Si alloy forms a melt and infiltrates the C/C matrix, and finally forms C/C-ZrC-SiC, C/C-Ti3SiC2-SiC, and C/C-ZrC-TiC-SiC composites. The C/C-ZrC-SiC composite with the highest ZrC content exhibited the lowest mass rate (2.6 ± 0.02 mg/s) and linear ablation rate (0.82 ± 0.04 μm/s), which were reduced by 43.5 and 50.8 %, respectively, compared to the unmodified C/C-ZrC-SiC composite.

Carbon species incorporation and carbon deposits are common in the manufacture process and application of yttria-stabilized zirconia (YSZ) ceramics, while the potential corrosion induced by the resultant carburization is unclear. The 3YSZ hollow fiber membranes were prepared by wet spinning method. A sintering procedure at 1300–1450 °C under 0.02 MPa oxygen partial pressure, and thereafter an oxidation treatment at 800 °C were applied to investigate the carbothermal reaction and carburization corrosion mechanism. It was found that the trace carbon species of 1.0–2.2 mol% derived from polymeric precursors triggered the carburizing strengthening of porous YSZ membranes without sacrificing porosity and deformability. However, the carburization corrosion also occurred at the mild oxidation treatment, resulting in deterioration in bending strength and integrated structure converting into fine grains. Raman spectra, XPS bands and HR-TEM images confirmed that the in-situ synthesized ZrCxOy oxidized into monoclinic ZrO2, and micro-cracking formed along grain boundaries, which led to substantial mechanical strength loss.

NbB2-NbC composite coatings were fabricated on the surface of TC4 by plasma spraying NbB2-NbC and Nb-B4C composite powders. The microstructure and properties of the as-prepared coatings were investigated, and the reaction mechanism of the Nb-B4C composite powder in the plasma jet and the formation mechanism of the NbB2-NbC coatings were revealed. During the plasma spraying process, NbB2-NbC composite powder underwent melting-depositing and no phase transformation occurred. The formation mechanism of the coating by plasma spraying Nb-B4C composite powder was solid phase diffusion-reaction-melting-deposition, and NbB2 and NbC were formed in situ by the solid phase diffusion reaction between Nb and B4C in the plasma jet. The coating obtained by reactive plasma spraying Nb-B4C composite powder has obvious lamellar structure, low porosity, high density, higher microhardness, good toughness, and better wear resistance compared with the coating prepared by NbB2-NbC composite powder, which is attributed to the exothermic reaction between Nb and B4C.

PurposeThe primary purpose of this paper is to identify the antecedent (i.e. leader's self-transcendent value) and outcomes (i.e. follower's environmental commitment and behavior) of transformational leadership. The second purpose is to examine the mediating role of transformational leadership plays in the relationship between leader's self-transcendent value and follower's environmental commitment and behavior.Design/methodology/approachMulti-source data were collected at multiple times in China. A total of 262 employees and their 64 supervisors completed the survey. The authors conducted a series of confirmatory factor analyses (CFAs) to verify the validity of the constructs and adopted the SPSS PROCESS macro with bootstrapping techniques to test the hypotheses.FindingsThe authors find that leader's self-transcendent value is an important antecedent of transformational leadership, and transformational leadership can enhance followers' environmental commitment and foster their environmental behavior. Besides, transformational leadership plays a significant mediating role between leader's self-transcendent value and follower's environmental commitment and behavior.Originality/valueThis study has developed an integrated model of the antecedents and outcomes of transformational leadership in the Chinese context. It also confirmed that transformational leadership mediates the process through which leader's self-transcendent value has a positive impact on follower's environmental commitment and behavior.

Converting carbon dioxide photocatalytically into fuels using solar energy is an attractive route to move away from a reliance on fossil fuels. Photothermal CO2 catalysis is one approach to achieve this, but improved materials that can more efficiently harvest and use solar energy are needed. Here, we report a supra-photothermal catalyst architecture—inspired by the greenhouse effect—that boosts the performance of a catalyst for CO2 hydrogenation compared to traditional photothermal catalyst designs. The catalyst consists of a nanoporous-silica-encapsulated nickel nanocrystal (Ni@p-SiO2), which is active for methanation and reverse water–gas shift reactions. Under illumination, the local temperatures achieved by Ni@p-SiO2 exceed those of Ni-based catalysts without the SiO2 shell. We suggest that the heat insulation and infrared shielding effects of the SiO2 sheath confine the photothermal energy of the nickel core, enabling a supra-photothermal effect. Catalyst sintering and coking is also lessened in Ni@p-SiO2, which may be due to spatial confinement effects. Light-driven catalytic conversion of CO2 to fuels and chemicals presents a way to reduce reliance on fossil fuels, but new strategies are needed to improve performance. Here the authors find that greenhouse effects can be exploited in photothermal catalysts to enhance their ability to produce methane and carbon monoxide.

The compression strength and breakage mechanism of a hierarchical porous sphere in hundred-micron size were investigated in the present work. 3 mol% yttria-stabilized zirconia (YSZ) microspheres were prepared by electro-spraying associated with phase inversion (ES-PI) technique. The characteristic compression strengths of the ES-PI microspheres were measured by quasi-static uniaxial compression test, which increased from 19 MPa to 155 MPa as the sintering temperature increased from 1100 °C to 1400 °C. With the similar porosity, the compression strength of the hierarchical structure microsphere was almost three times higher than that of the hollow microsphere. Further, the breakage mechanism of the ES-PI microspheres was proposed by the honeycomb model of cellular materials, which suggested that the breakage of the ES-PI microsphere initiated from the elastic instability of the walls around the finger-like pores. These findings can help the mechanical performance optimization for ceramic microspheres with lightweight structure.

Inherent drawbacks associated with drug-eluting stents have prompted the development of bioresorbable cardiovascular stents. Additive manufacturing (3-dimentional (3D) printing) has been widely applied in medical devices. In this study, we develop a novel screw extrusion-based 3D printing system with a new designed mini-screw extruder to fabricate stents. A stent with a zero Poisson’s ratio (ZPR) structure is designed, and a preliminary monofilament test is conducted to investigate appropriate fabrication parameters. 3D-printed stents with different geometric structures are fabricated and analyzed by observation of the surface morphology. An evaluation of the mechanical properties and a preliminary biological evaluation of 3D-printed stents with different parameters are carried out. In conclusion, the screw extrusion-based 3D printing system shows potential for customizable stent fabrication.

Alloyed green-emitting CdZnSeS/ZnS quantum dots (QDs) demonstrate potential applications in solid-state lighting and displays owing to their various advantages, such as high color purity, light conversion efficiency, and color rendering index. However, their applications in white light-emitting diodes (WLEDs) are limited by their poor photostabilities on blue-emitting gallium nitride (GaN) LED chips. In this study, the effect of the specific surface area (SSA) in the coating layers on the photostabilities of QDs was investigated. SSA was adjusted by controlling the proportions of dense aluminum oxide (AlOX) layers and porous silica dioxide (SiO2) layers to fabricate QD protective layers via a catalyst-free sol-gel method. The results showed that the synthesized AlOX possessing the lowest SSA among the synthesis protective layers presented the best QD photostabilities on the LED chips. Moreover, they exhibited a 9.9-fold increase in the operational lifetime (T80) compared to that of pristine QDs. In addition, the QD-based WLED achieved an excellent display performance with a wide color gamut (115%) of the National Television System Committee (NTSC) color gamut standard. This approach offers a promising strategy for enhancing the QD photostabilities for applications in solid-state lighting and displays by coating the protective layers on the QD surface.

RFID techniques have been extensively used in sensing systems due to their low cost. However, limited by the structural simplicity, collision is one key issue which is inevitable in RFID systems, thus limiting the accuracy and scalability of such sensing systems. Existing anti-collision techniques try to enable parallel decoding without sensing based applications in mind, which can not operate on COTS RFID systems. To address the issue, we propose COFFEE, which enables parallel channel estimation of COTS passive tags by harnessing the collision. We revisit the physical layer design of current standard. By exploiting the characteristics of low sampling rate and channel diversity of RFID tags, we separate the collided data and extract the channels of the collided tags. We also propose a tag identification algorithm which explores history channel information and identify the tags without decoding. COFFEE is compatible with current COTS RFID standards which can be applied to all RFID-based sensing systems without any modification on tag side. To evaluate the real world performance of our system, we build a prototype and conduct extensive experiments. The experimental results show that we can achieve up to 7.33x median time resolution gain for the best case and 3.42x median gain on average.

The surface reconstruction of iridium-based derivatives (AxIryOz) was extensively demonstrated to have an excellent oxygen evolution reaction (OER) performance in an acidic medium. It is urgent to use various spectroscopy and computational methods to explore the electronic state changes in the surface reconstruction process. Herein, the underestimated Lu2Ir2O7 was synthesized and investigated. Four typical forms of electrochemistry impedance spectra involved in the reconstruction process revealed three dominating forms of reconstructed pyrochlore in the OER stage, including the inner intact pyrochlore, mid metastable [IrO6]-[IrO6] framework, and the outer collapse amorphous layer. The enhancing electron transport efficiency of the corner-shared [IrO6]-[IrO6] framework was revealed as a critical role in acidic systems. The density of state (DOS) for the constructed [IrO6]-[IrO6] framework corroborated the enhancement of Ir-O hybridization and the downshift of the d-band center. Additionally, we contrast the pristine and reconstruction properties of the Pr2Ir2O7, Eu2Ir2O7, and Lu2Ir2O7 in alkaline and acidic media. The DOS and the XANES results reveal the scale relationship between the O 2p band center and the intrinsic activity for bulk pyrochlore in alkaline media. The highest O 2p center and the highest Ir-O hybridization of Lu2Ir2O7 exhibited the best OER performance among the Ir-based pyrochlore, up to a ninefold improvement in Ir-mass activity compared to IrO2. Our findings emphasize the electrochemical behavior of the reconstruction process for activated water-splitting performance.

The recovery of carbon emissions in the past 2 years has alerted us that carbon emissions are a long-term process, and setting short-term emission reduction targets can more effectively curb the rising trend of carbon emissions. Therefore, the research on short-term prediction of carbon emissions is particularly important. In this paper, the idea of “decomposition-prediction” is put forward in the short-term prediction of carbon emissions, and the combined model of “decomposition-prediction” is constructed. The model is composed of ensemble empirical mode decomposition (EEMD) and the backpropagation neural network based on particle swarm optimization (PSOBP). It is also the first time that EEMD has been applied to the field of carbon emission prediction. Firstly, EEMD is used to decompose the daily carbon emission monitoring data into 6 modal functions and one residual sequence, and the partial autocorrelation function (PACF) is used to determine the input of each modal function. Then, PSOBP was used to predict. Finally, adding the prediction results of each sequence to get the final prediction results. To verify the effectiveness and superiority of the EEMD-PSOBP model, 14 comparative models were constructed, and the prediction effect of the models was evaluated by R2, RMSE, and MAPE. All the prediction results show that the proposed model has the best prediction performance (R2=0.9507, RMSE=0.3431, MAPE=0.093). Compared with PSOBP, the R2 of EEMD-PSOBP was increased by 63.58%, and RMSE and MAPE were decreased by 65.18% and 64.23%, respectively. The accuracy of prediction can be improved significantly by decomposing before predicting. It was also found that EEMD had the highest predictive performance improvement. Therefore, this model will have broad development prospects in the field of short-term carbon emission prediction in the future.

The organotypic human air‐liquid‐interface (ALI) airway tissue model has been used as an in vitro cell culture system for evaluating the toxicity of inhaled substances. ALI airway cultures are highly differentiated, which has made it challenging to evaluate genetic toxicology endpoints. In the current study, we assayed DNA damage with the high‐throughput CometChip assay and quantified mutagenesis with Duplex Sequencing, an error‐corrected next‐generation sequencing method capable of detecting a single mutation per 107 base pairs. Fully differentiated human ALI airway cultures were treated from the basolateral side with 6.25 to 100 μg/mL ethyl methanesulfonate (EMS) over a period of 28 days. CometChip assays were conducted after 3 and 28 days of treatment, and Duplex Sequencing after 28 days of treatment. Treating the airway cultures with EMS resulted in time‐ and concentration‐dependent increases in DNA damage and a concentration‐dependent increase in mutant frequency. The mutations observed in the EMS‐treated cultures were predominantly C → T transitions and exhibited a unique trinucleotide signature relative to the negative control. Measurement of physiological endpoints indicated that the EMS treatments had no effect on anti‐p63‐positive basal cell frequency, but produced concentration‐responsive increases in cytotoxicity and perturbations in cell morphology, along with concentration‐responsive decreases in culture viability, goblet cell and anti‐Ki67‐positive proliferating cell frequency, cilia beating frequency, and mucin secretion. The results indicate that a unified 28‐day study can be used to measure several important safety endpoints in physiologically relevant human in vitro ALI airway cultures, including DNA damage, mutagenicity, and tissue‐specific general toxicity.

Covering with plastic film in fall and planting through the film in spring is an effective drought-resistance, potato-cultivation method. To achieve proper under-plastic-film, hill-drop potato seeding, the geometry of an existing five-link planter mechanism that is driven synchronously by two cranks rotating in the same direction has been refined through bivariate plots and numerical optimization. For this purpose, novel quantitative measures of the geometry of the crunode portion of the dibber-tip path have been introduced. The prototype planter mechanism described in detail elsewhere has then been configured according to the three optimum kinematic solutions obtained, and field tests have been carried out. All three configurations satisfied the imposed agronomic requirements of potato planting through the plastic film, with one setup performing better than the other two, and then a previously reported solution obtained through manually conducted optimization.

We investigate periodic solutions of regime-switching jump diffusions. We first show the well-posedness of solutions to stochastic differential equations corresponding to the hybrid system. Then, we derive the strong Feller property and irreducibility of the associated time-inhomogeneous semigroups. Finally, we establish the existence and uniqueness of periodic solutions. Concrete examples are presented to illustrate the results.

The influences of extracellular polymeric substances (EPS) on heavy metal ions biosorption by acidophilic microorganisms have not been systematically reported previously. In this study, three acidophilic strains were chosen as model microbes to evaluate the effect of EPS on the adsorption of heavy metal ions (Cu2+, Ni2+, Cd2+, Zn2+) from aqueous solutions. The results indicated that buffering capacities and protonation/deprotonation abilities of these acidophiles were enhanced in the presence of EPS. Acid–base titration and FTIR analysis revealed the carboxyl, phosphoryl, amino and hydroxyl groups have provided EPS binding sites for heavy metal ions via deprotonation. The extreme thermophilic archaea had the highest total site concentration of 7.93 ± 0.52 × 10−4 mol/g on the cell surface. Meanwhile, cells with EPS had better performance in adsorption when compared with cells without EPS. The biosorption abilities of the extreme thermophilic archaea with EPS toward Cu2+, Ni2+, Cd2+ and Zn2+ were 48 μmol/g, 37.5 μmol/g, 32.5 μmol/g and 28 μmol/g, respectively. This study could provide theoretical support for the treatment of heavy metal ions in acid mine drainage by acidophiles.

The effects of SiC on microstructure and properties of plasma sprayed ZrB2–ZrC composite coating were investigated. Plasma sprayed ZrB2–ZrC and ZrB2–ZrC–SiC composite coatings were prepared and compared. The addition of SiC could improve the density of the ZrB2–ZrC–SiC coating that lead to better mechanical properties. The reason was that SiC improved the melting state of powder feedstocks during plasma spraying process and refined grains in ZrB2–ZrC–SiC composite coating.

Steam reforming (SR) of bio-oil has been considered as one of the promising methods for hydrogen production. In this paper, cerium modified Ni/Attapulgite (ATP) catalysts were successfully synthesized by traditional chemical precipitation method and utilized for SR of various bio-oil derived oxygenated model compounds. The effect of Ce content on the structural properties of Ni/ATP was investigated by ICP-OES, N2 adsorption–desorption, XRD, H2-TPR and HRTEM characterizations. The results exhibited that 10Ce–Ni/ATP catalyst had the strongest metal-support interaction and highly dispersion of Ni species with smallest particle size of 6.21 nm. Therefore, it presented the maximum ethanol conversion of 97.21% and H2 yield of 83.15% at relative lower reaction temperature 500 °C during 4 h of SR of ethanol (SRE). In addition, it unfolded promising performance for SR of acetic acid (SRAA) and acetone (SRA). Furthermore, the influence of different oxygenates on the amount and nature of carbon deposits in used 10Ce–Ni/ATP catalyst was revealed by TG and Raman analyses. It found that the types of feedstock significantly affected the carbon species and amount and the formation of graphic layers around the Ni metal sites was the mainly factor for rapid deactivation of 10Ce–Ni/ATP during 4 h of SRA reaction.

The W18O49 nanoparticles were synthesized by solvothermal method with tungsten chloride as raw material and n-propanol as solvent. Polyethylene glycol 400 (PEG-400) was modified for W18O49 nanoparticles (W18O49@PEG). The structure and morphology of W18O49 and W18O49@PEG were characterized by XRD and SEM. Methylene blue aqueous solution was used as wastewater adsorption model. And the comparative experiments with other absorbent materials, such as artificial zeolite and activated carbon were also conducted. The results revealed that after modifying by PEG-400, W18O49 has a better adsorption performance than other materials due to its large specific surface area and high surface energy. Finally adsorption circulation experiment was performed，the results indicate that the W18O49@PEG nanoparticles show great potential in the treatment of colored wastewater.

Granular friction behaviors are crucial for understanding the ubiquitous packing and flow phenomena in nature and industrial production. In this study, a customized experimental apparatus that can simultaneously measure the time history of normal and tangential forces on the inside-shearing unit is employed to investigate the granular friction behaviors during a linear reciprocating sliding process. It is observed that the evolution behaviors of two normal forces distributed separately on the shearing unit can qualitatively reflect the effects of the force chain network. During the half-loop of the reciprocating sliding, the total normal force, which indicates the load-bearing capacity of the granular system, experiences the following typical stages: decreases abruptly and stabilizes momentarily, further decreases significantly to the minimum, gradually increases to the maximum, and then remains stable. These stages are associated closely with the relaxation, collapse, reconstruction, and stabilization of the force chain, respectively. Interestingly, the coefficient of friction (COF) can reach a stable value rapidly within the initial sliding stage and subsequently remain constant. The average COF within stable ranges decreases significantly with the external load G in the power-function form, G−0.5. Meanwhile, the COF increases slightly with the sliding velocity. Finally, a complete illustration of the dependences of the granular COF on the external load and sliding velocity is provided. Our study contributes to granular friction research by providing an innovative experimental approach for directly measuring the COF and implicitly correlating the evolution of the force chain network.

The traditional acid leaching method for recycling valuable metals from the cathode material of spent lithium-ion batteries (LIBs) has encountered the problems of high consumption of H₂SO₄ and reducing agents. In this study, a novel process has been developed to strengthen valuable metal recovery from spent lithium-ion batteries by reductive thermal treatment and electrochemical leaching. With the help of reductive thermal treatment under the conditions of R = 1600 °C and 120 min, the layered structure of the cathode material LiNi₁/₃Co₁/₃Mn₁/₃O₂ is reduced to a mixture of Li₂CO₃, NiO, Co₃O₄, Mn₂O₃, and MnO₂ due to the oxygen releasing from the framework. The destruction of the layered crystal structure reduces the difficulty of leaching valuable metals. 90.59% Ni, 90.53% Co, 66.40% Mn, and 100% Li were leached under the optimal conditions of 20 mL/g liquid–solid ratio, 1.5 M H₂SO₄, 0.8 A, and 150 min at room temperature. Comparing the processes of reductive thermal treatment with acid leaching and direct electrochemical leaching of spent cathode material under the same leaching conditions, the proposed approach can achieve the highest metal recovery and economic benefits. It can be implemented at room temperature, decreases the application of reducing agent and sulfuric acid, and makes full use of spent graphite, resulting in a greener recycling process for recovering valuable metals from spent LIBs.

The increasing excess electromagnetic wave (EMW) energies causes potential electromagnetic radiation pollution. It gives rise to more and more attention on designing environmentally friendly, efficient and suitable for large-scale industrial production of daily EMW absorbers. Carbon matrix composites modified with magnetic particles occupy the majority of these candidate absorbers. However, the preparation is still in its infancy. Here, we creatively mixed Fe(acac)3 with polyacrylonitrile (PAN) spinning solution, and then prepared magnetic carbon-based composites by in-situ pyrolysis of the obtained electrospun fibers (Fe(acac)3/PAN) at different temperatures. The SEM images display a fractured fibrous material with porous structure and uniform distribution of magnetic particles on the outer surface and inside. The XRD and XPS results indicate the composites consist of Fe3O4, Fe3C and carbon matrix. Besides, the thermal phase transition occurs with the pyrolysis temperature increasing from 300 to 1000 °C, and the formed Fe3O4 reacts with the carbon matrix to form Fe3C. As a result, the corresponding magnetic properties and electromagnetic properties improve. MCF-1000 exhibits enhanced EMW absorption performance with a minimum RL ( $${RL}_{\mathrm{min}}$$ ) value of − 29.27 dB at a matching frequency ( $${f}_{m}$$ ) of 11.68 GHz, a matching thickness ( $${t}_{m}$$ ) as low as 1.50 mm, and an effective frequency bandwidth as broad as 4.50 GHz from 13.50 to 18.00 GHz at a fixed thickness as thin as 1.13 mm. Further investigations indicate that such good EMW absorption behavior is attributed to the optimal impedance matching and the weakened eddy current effect which are both benefited by the thermal phase transition effect. The results provide theoretical and practical experience for the industrial large-scale preparation of a kind of EMW absorbers.

In this paper, an investigation into the effect of explicit non-linear turbulence modelling on anisotropic turbulence flows is presented. Such anisotropic turbulence flows are typified in the corner separations in turbomachinery. The commonly used Reynolds-Averaged Navier-Stokes (RANS) turbulence closures, in which the Reynolds stress tensor is modelled by the Boussinesq (linear) constitutive relation with the mean strain-rate tensor, often struggle to predict corner separation with reasonable accuracy. The physical reason for this modelling deficiency is partially attributable to the Boussinesq hypothesis which does not count for the turbulence anisotropy, whilst in a corner separation, the flow is subject to three-dimensional (3D) shear and the effects due to turbulence anisotropy may not be ignored. In light of this, an explicit non-linear Reynolds stress-strain constitutive relation developed by Menter et al. is adopted as a modification of the Reynolds-stress anisotropy. Coupled with the Menter’s hybrid "k-ω" ⁄"k-ε" turbulence model, this non-linear constitutive relation gives significantly improved predictions for the corner separation flows within a compressor cascade, at both the design and off-design flow conditions. The mean vorticity field are studied to further investigate the physical reasons for these improvements, highlighting its potential for the widespread applications in the corner separation prediction.

In this paper we consider the problem of stochastic H 2 / H ∞ control for Poisson jump-diffusion system driven by Brownian motion and Poisson process. Firstly, a mean-field stochastic bounded real lemma(SBRL) is derived in this paper. Secondly, a sufficient condition for the solvability of Poisson jump-diffusion linear quadratic (LQ) optimal control of discrete-time mean-field type is presented. Thirdly, based on the results of SBRL and LQ control, the sufficient conditions for the existence of mean-field stochastic H 2 / H ∞ control of Poisson jump-diffusion system are established by the solvability of the coupled matrix value equation. Finally, an example of recursive algorithm is presented to demonstrate the effectiveness of the proposed theory.

The consumption of rechargeable batteries has been increasing rapidly. High demand on specific metals for battery manufacturing and environmental impacts from battery disposal make it essential to recycle and retrieve materials from the spent batteries. There have been some review articles on battery recycling, mostly on the technologies for the materials recovery and some on life cycle assessment (LCA). To develop a truly sustainable battery industry, however, battery recycling must be commercially viable. Yet, very limited information on the economics of battery recycling is available. This paper examines technologies and research efforts in battery recycling from the perspective of economic viability and life cycle inventory. With the support of up-to-date statistics, the paper also comments on the challenges facing battery recycling, and the role of battery design and circular economy in the sustainable development of battery industry where governments, manufacturers and consumers all play a part.

The emergence of optical Internet of Things (optical-IoT) for sixth-generation (6G) networks has been envisaged to relieve the bandwidth congestion in the conventional radio frequency (RF) channel, and to support the ever-increasing number of smart devices. Among the plethora of device innovations deemed essential for fortifying the development, herein we report on the visible-to-near-infrared color-conversion luminescent-dyes based on lead sulphide quantum dots (PbS QDs), so as to achieve an eye-safe high-speed optical link. The solution-processed PbS QDs exhibited strong absorption in the visible range, radiative recombination lifetime of 6.4 $\mu$s, as well as high photoluminescence quantum yield of up to 88%. Our proof-of-principle demonstration based on an orthogonal frequency-division multiplexing (OFDM) modulation scheme established an infrared data transmission of 0.27 Mbit/s, readily supporting an indoor optical-IoT system, and shed light on the possibility for PbS-integrated transceivers in supporting remote access control of multiple nodes. We further envisaged that our investigations could find applications in future development of solution-processable PbS-integrated luminescent fibers, concentrators, and waveguides for high-speed optical receivers.

It is well-known that effective charge transfer within the catalyst structure is critical to the improvement of the performance of catalytic reaction. Herein, we reported three functionalized polyo...

Vanadium nitride (VN)-based materials have been investigated as negative electrode materials for supercapacitors (SCs) owing to their high theoretical capacitances and suitable negative potential windows. However, viable VN-based negative electrode materials suffer from irreversible electrochemical oxidation of the soluble vanadium species, leading to rapid capacitance fading when operated in aqueous electrolytes. Developing a versatile approach to enhance the stability of VN in aqueous electrolytes is still a challenge. Here, an interface engineering strategy is developed to intentionally introduce surface nanolayers of vanadium oxides (VOX) as a reactive template on the VN surface to formulate well-designed polypyrrole@VNO (Ppy@VNO) core-shell nanowires (NWs) incorporated into a 3D porous N-doped graphene (NG) hybrid aerogel as a durable negative electrode for SCs. Experimental and theoretical investigations reveal that the in-situ constructed Ppy@VNO core-shell host can offer more efficient pathways for rapid electron/ion transport and accessible electroactive sites. Most importantly, a reversible surface redox reaction is realized through the transformation of the valence state of V, and a long cyclic stability is achieved. The Ppy@VNO/NG hybrid aerogel can deliver a high specific capacitance of 650 F g−1 at 1 A g−1 with approximately 70.7% capacitance retention (up to the twenty fold current density), and an excellent cycling stability without any capacitance de cay after 10,000 cycles at both low and high current densities (1 and 10 A g−1, respectively). This work paves the way for the development of advanced electrode materials for SCs.

Room-temperature (RT) sodium-sulfur (Na/S) battery has been considered as a promising energy storage system due to suitable operating temperature, high theoretical energy density, and low cost. However, it has a poor cycle life and low reversible capacity. In this work, we report a long-life RT-Na/S battery with the help of amorphous porous silica as a sulfur host. The sulfur is loaded into amorphous silica by a facile dipping method, and the optimal sulfur loading can be as high as 73.48 wt.%. The molecular dynamics simulation and first-principles calculations suggest that the complex pores, acting as micro-containers and the formation of Na-O chemical bonds between amorphous silica and sodium polysulfide, give the electrodes a strong ability to inhibit sodium polysulfide shuttle. This would give rise to effectively avoiding the loss of active sulfur, corresponding to a superior capacity (i.e., average discharge capacities of 1106, 1074, 1060, 1036, and 1000 mAh·g -1 at 1, 2, 3, 5, and 10 A·g -1 , respectively.) and an excellent cyclability even at 10 A·g -1 (nearly 100% coulomb efficiency and high reversible capacity of 955.8 mAh·g -1 after 1460 cycles). The present results introduce new insights into the inhibition of "shuttle effect" of sodium polysulfide and develop a promising sulfur electrode for advanced RT sodium-sulfur batteries.

Surface coordination chemistry is important in areas such as adsorption, separation, and catalysts. In this work, surface coordination interactions of benzohydroxamic acid (BHA) with the lead ion [Pb(II)] adsorbed on the cassiterite surface have been investigated by first-principles calculations due to its great significance in froth flotation. Cluster calculations show that BHA possesses the weakest chelation with Pb(II) due to the electron withdrawal ability of the benzyl ring in comparison with other hydroxamic acids. Pb(II) thermodynamically prefers to react with the cassiterite surface rather than BHA. On the other hand, the partial density of states and the atomic overlap populations have consistently verified that the adsorption of BHA results in a better symmetry in electron densities than the hydrated Pb(II). The electron density maps and the electronic localization functions have further visualized the rearrangement of the 6s2 lone pair around the lead atom. It can be concluded that the surface coordination mechanisms of Pb(II) on oxide minerals can be attributed to the coordination ability of BHA and the unique electronic structure of Pb(II), which accounts for the reported better flotation performance of the pre-assemble strategy than the pre-activating approach. This work sheds some new light on the unique coordination activation mechanism of metal ions on oxide mineral surfaces. It should be instructive to design and screen new environment-friendly flotation reagents and flotation flowsheets.

The outbreak of coronavirus disease 2019 (COVID-19) caused by SARS CoV-2 is ongoing and a serious threat to global public health. It is essential to detect the disease quickly and immediately to isolate the infected individuals. Nevertheless, the current widely used PCR and immunoassay-based methods suffer from false negative results and delays in diagnosis. Herein, a high-throughput serum peptidome profiling method based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is developed for efficient detection of COVID-19. We analyzed the serum samples from 146 COVID-19 patients and 152 control cases (including 73 non-COVID-19 patients with similar clinical symptoms, 33 tuberculosis patients, and 46 healthy individuals). After MS data processing and feature selection, eight machine learning methods were used to build classification models. A logistic regression machine learning model with 25 feature peaks achieved the highest accuracy (99%), with sensitivity of 98% and specificity of 100%, for the detection of COVID-19. This result demonstrated a great potential of the method for screening, routine surveillance, and diagnosis of COVID-19 in large populations, which is an important part of the pandemic control.

We consider fast solving a class of spatial fractional diffusion equations where the fractional differential operators are comprised of Riemann–Liouville and Caputo fractional derivatives. A circulant-based approximate inverse preconditioner is established for the discrete linear systems resulted from the finite difference discretization of this kind of fractional diffusion equations. By sufficiently exploring the Toeplitz-like structure and the rapid decay properties of the internal sub-matrices in the coefficient matrix, we show that the spectrum of the preconditioned matrix is clustered around one. Numerical experiments are performed to demonstrate the effectiveness of the proposed preconditioner.

We obtain $q$-analogues of several series for powers of $\pi$. For example, the identity $$\sum_{k=0}^\infty\frac{(-1)^k}{(2k+1)^3}=\frac{\pi^3}{32}$$ has the following $q$-analogue: \begin{equation*} \sum_{k=0}^\infty(-1)^k\frac{q^{2k}(1+q^{2k+1})}{(1-q^{2k+1})^3}=\frac{(q^2;q^4)_{\infty}^2(q^4;q^4)_{\infty}^6} {(q;q^2)_{\infty}^4}, \end{equation*} where $q$ is any complex number with $|q, Comment: 10 pages. Add Theorem 1.2

Mono-functional chelating collectors exhibit limited selectivity in the flotation of minerals. In particular, the selective separation of calcium minerals presents a significant challenge because mono-functional chelating collectors, such as fatty acid, indistinguishably adsorb onto mineral surfaces by coordinating with the same metal cation (Ca2+). Thus, there is an urgent need to develop new-mode-functional collectors to separate calcium minerals and a need to understand the underlying chemoselectivity. Given the difference of the hydrogen bonding ability of anions with fluorite, calcite and scheelite surfaces, the introduction of additional hydrogen bonding functional groups into collector molecules is a novel strategy to improve selectivity. In this study, a hydrogen and coordination bonding (bi-functional) collector, 2-cyano-N-ethylcarbamoyl acetamide (CEA) was developed, which could form coordination bonds with the Ca2+ ions (by carbonyl groups) and hydrogen bonds with the anions (by amino groups) on calcium mineral surfaces. The results of flotation tests showed that CEA can selectively separate fluorite and calcite from scheelite at pH 7. The promising selectivity of CEA lies in both the electrical properties and the anions' hydrogen bonding ability with the three calcium minerals. The negatively charged scheelite surfaces are not conducive to coordination bonding with CEA while the positively charged fluorite and calcite surfaces are. Besides, the hydrogen bonding ability of fluorite (F-) and calcite (CO32-) with carbamido in CEA is higher than that of scheelite (WO42-), and this also plays an essential role. This coordination and hydrogen bonding based surfactant design protocol has a great potential in the development of tail-made collectors/depressants for the separation of other oxidized minerals.

The qualitative relationship between hydrogen concentration and notch tensile strength has been investigated for 5Ni-16Cr-Mo steel with different strength. The notch tensile strength was determined by means of slow strain rate test (SSRT) on circumferentially notched round bar specimens with the notch root radius of 0.15 mm after hydrogen charging. Meanwhile, the hydrogen diffusion behaviors of various strength steel were studied by thermal desorption spectroscopy (TDS) analysis. The SSRT results show that the T460 steel has higher susceptibility of hydrogen embrittlement in contrast with T520 steel. The activation energies and microstructure indicate that the dislocations and interfaces of martensitic laths are hydrogen traps in 5Ni-16Cr-Mo steel. By SSRT, the elastic limit of charged specimen loaded in air is higher than the flow stress without hydrogen charging before unloading, while the difference is defined as hydrogen-induced stress. The value of hydrogen-induced stress σ* increases linearly with hydrogen concentration: σ*=−0.622+2.015C0. The finite element analysis results of stress distributions near the notch tip have shown that the maximum principal stress increases with the notch root radius decreasing.

The dynamics of micro-/nanoscale plates are extremely sensitive to external conditions. Here, the vibration of a submicron-thick circular plate exposed to its ambient environment was investigated. The obtained results indicate that the vibration behavior of circular plates shows a strong dependence on the surrounding conditions. Mode pair splitting was observed in a vibration experiment. One crucial influence factor is the asymmetry due to exposure to an ambient environment. Therefore, numerical analyses were performed to identify the vibration of a circular plate due to symmetry breaking. A detailed finite element analysis revealed that symmetry breaking can lead not only to the splitting of some pairs of modes but also to shifts in natural frequencies. In addition, the relationships between the asymmetry and the frequency shift were identified together with the differences in the mode pairs for the circular plates. This study should be of great help for understanding the vibration of submicron plates and the design of submicron-scale resonators and biological sensors.

Adverse drug reactions of Traditional Chinese medicine injection mainly manifested as pseudo-allergic reactions. In the present study, ginsenoside Rd, Ro and Rg3 were identified as pseudo-allergic components in Shengmai Injection by a high-expression Mas-related G protein coupled receptor X2 cell membrane chromatography coupled online with high-performance liquid chromatography and mass spectrometry. Their pseudo-allergic activities were evaluated by in vitro and in vivo assay. The three compounds were further found to induce pseudo-allergic reaction through Mas-related G protein coupled receptor X2. Therefore, we concluded that ginsenoside Rd, Ro and Rg3 may be potential allergens cause pseudo-allergic reactions. This study might be helpful for the safe use of Shengmai Injection. This article is protected by copyright. All rights reserved.

Background Residual stress plays a fundamental role in maintaining the homeostatic state of the aortic wall. Since residual stress was discovered via the opening angle experiment, a large body of literature has been dedicated to this topic of research. However, current analytical approaches estimating the residual stress of the aorta still suffer from a number of limitations. In this study, we improved the current approaches by addressing the following limitations: 1) the variations in the residual deformations are not incorporated, 2) the load-free condition along the axis of the aorta is not properly accounted for, and 3) the obtained axial residual stretch of the media mismatches with the experimental data. Method In our newly-proposed analytical method, the load-free condition was imposed at the end cross-section of the residually-stressed aorta. The solution procedure was also modified to ensure that the experimentally measured residual stretches were properly specified. Moreover, the opening angles of the media and the adventitia were incorporated as variables so that their influences on the residual stress field can be investigated. Results Compared with other methods, this method resulted in a similar pattern of residual stress distribution in the intima and adventitia. In the media, however, this method showed that the residual stresses were tensile in both circumferential and axial directions, in contrast to other methods with the pattern of half compressive and half tensile in the circumferential direction and totally compressive in the axial direction. The axial residual stretch of the media, the opening angle of the media and the opening angle of the adventitia had significant influence on the residual stress and in vivo stress distribution. The inter-layer in vivo stress difference was evaluated to support future finite element simulation of residual stress using the tissue growth method. Moreover, the influence of the residual stress on the pressure–radius response was quantified, and the residual stress led to more than 360% increase in distensibility. Conclusions The proposed method alleviated some limitations of previous analytical methods and would facilitate the accurate stress analysis and more accurate material parameter identification of the aortic wall.

A novel Fe-enriched lamella sandwich phase (χ-phase) has been found to precipitate along the basal (0001)Mg planes in the heat-treated Mg-Gd-Fe alloy and its structure is clearly revealed by means of atomic-resolution transmission electron microscopy. The layered χ-phase only has a thickness of mono-unit-cell and consists invariably of ten atomic layers stacking along the [0001]Mg direction, of which the outermost atomic layers had larger in-plane atom-pillar spacing than the inner layers. Fe/Gd atoms are mainly enriched in the outer four atomic layers in the χ-phase, forming two structurally unsymmetrical four-layer shells to sandwich the middle two Mg layers. An atomic model has been proposed for this layered sandwich-structured χ-phase.

The goal of this paper is threefold. First, we survey the existing results on Hunt’s hypothesis (H) for Markov processes and Getoor’s conjecture for Levy processes. Second, we investigate (H) for multidimensional Levy processes from the viewpoint of projections. Third, we present a few open questions for further study.

Context Naoxintong (NXT), a prescribed traditional Chinese medicine, widely used in cerebrovascular and cardiovascular diseases, could be effective in diabetic wounds. Objective This study evaluates the wound healing activity of NXT by employing an excisional wound splinting model. Materials and methods NXT was dissolved in saline and given daily by gavage. Wounds were induced at the dorsum of non-diabetic (db/+) and diabetic (db/db) mice and treated with saline or 700 mg/kg/d NXT for 16 days. Wound closure was measured every four days. Extracellular matrix (ECM) remodelling, collagen deposition, leukocyte infiltration and expression of Col-3, CK14, CXCL1, CXCL2, MPO, Ly6G, CD68, CCR7, CD206, p-JAK1, p-STAT3 and p-STAT6 was analysed. Results NXT significantly accelerated rate of wound closure increased from 70% to 84%, accompanied by up-regulation of collagen deposition and ECM at days 16 post-injury. Moreover, NXT alleviated neutrophil infiltration, accompanied by down-regulation of CXCL1 and CXCL2 mRNA expression. In addition, NXT markedly augmented neutrophil efferocytosis. In diabetic wounds, the levels of M1 marker gene (CCR7) increased, while M2 marker gene (CD206) decreased, demonstrating a pro-inflammatory shift. Application of NXT increased M2 macrophage phenotype in db/db mice. Mechanistically, NXT treatment increased expression level of p-STAT3 and p-STAT6 at days 3 post-injury, indicating NXT mediated macrophages towards M2 phenotype and alleviated inflammation in diabetic wounds by activation of STAT3 and STAT6. Conclusions Our study provides evidence that NXT accelerates diabetic wound healing by attenuating inflammatory response, which provides an important basis for use of NXT in the treatment of chronic diabetic wound healing.

MoO3–Al composite powders were used for preparing in situ composite coatings. Effects of the composition of MoO3–Al composite powder on the microstructure and properties of the as-prepared coatings were investigated. The results show that the main phases of the as-prepared coatings were γ-Al2O3 and Mo. An optimal composition (63 wt%) of MoO3 in MoO3–Al composite powder was demonstrated. The porosity of the as-prepared composite coatings decreased first and then increased with the increase of MoO3. This is attributed to the fact that the melting state of the powder during plasma spraying is closely involved in the content of MoO3. The coating prepared by composite powder with 63 wt% MoO3 had the most Al2O3 and the highest microhardness. The wear resistance of 63 wt% MoO3 composite coating was the best among four coatings with different content of MoO3, which is attributed to its high hardness and good toughness.

This study aims to investigate the correlation between flow velocity and cavitation erosion (CE) characteristics of high-velocity oxygen-fuel (HVOF) sprayed Cr3C2-NiCr (CN) and WC-Cr3C2-Ni (WCN) coatings in 3.5 wt% NaCl medium, except for the microstructures, mechanical properties and electrochemical behaviors. In comparison with the CN coating, the WCN coating shows higher values of elastic modulus (E), hardness (H), H/E and H3/E2 as well as lower porosity, resulting in lower volume loss rate (VLR) and enhanced CE resistance in NaCl medium at each value of flow velocity. The VLR values of both coatings increase as the flow velocity increases. The change of the CE progresses in NaCl medium of the CN coating is the formation of cavitation pinholes, pits, craters and oxidation films coupled with the exfoliation of chromium carbide particles when the flow velocity is 23.4 and 33.5 m s−1 as well as the brittle fracture structure with layers delamination accompanied by the oxidation films when the flow velocity is 41.9 m s−1. In a wide flow velocity range, the formation of cavitation pinholes, pits and micro-cracks along with the oxidation films are addressed as the dominant CE mechanism in NaCl medium of the WCN coating.

Chemotherapy and surgery are commonly used clinical treatments for breast cancer. However, unsatisfactory therapeutic effects, unavoidable side effects, and the removal of breast tissue during surgery are still major obstacles to be overcome during breast-cancer treatment. To overcome the aforementioned issues, a biomimetic and thermosensitive hydrogel encapsulating reactive oxygen species (ROS)-sensitive tegafur (TF)-protoporphyrin IX (PpIX) heterodimers (TTP) was prepared aimed at the strategy of synergizing chemotherapy and photodynamic therapy. TF was grafted onto the photosensitizer PpIX through ROS-sensitive thioether bonds. Under 630 nm laser irradiation, the ROS concentration in tumors was increased to help drug release. The "on-demand" drug release maximized the therapeutic effects of TF and effectively reduced its toxicity. Particularly, the ROS concentration was increased, and it was expected that the tumor-cell-killing abilities of ROS could be exploited. A hydrogel formed from temperature-sensitive chitosan and silk sericin was selected as a drug carrier, which formed a drug reservoir intratumorally after intratumoral injection. Intratumoral injection gave the drug precise and long-term release behavior, which allowed for the clever avoidance of various physical and biological barriers in vivo. In vivo and in vitro studies prove that the use of this TTP hydrogel provides a new attempt to overcome the many difficulties related to breast-cancer treatment simultaneously, and this study opens up new paths for breast-cancer treatment.

To improve the ablation performance of carbon/carbon (C/C) composite materials, a WSi2–ZrSi2 composite-reinforced ZrxHf1–xC/SiC coating was prepared on the substrate surface via patterning strengthening method. The results show that this coating can protect the substrate from failure for 300 s under an oxyacetylene flame at 2600 °C. Owing to the presence of W, an extremely dense oxide layer was formed on the surface of the coating during initial ablation, which progressively led to the expulsion of the product of oxidation (WO3) from the inner layer, as well as to holes and cracks on healing the coating surface, thereby significantly improving the ablation performance of the C/C composites. In addition, the excellent ablative performance and mechanism of the coating were analysed using volatility diagrams.

Introducing a metal sulfide-based co-catalyst is an effective strategy to substantially enhance the Fenton reaction. Manipulation of the co-catalyst's structure is expected to further boost the co-catalytic capability. Herein, we demonstrate that the intrinsic high-defect surface of a natural molybdenite material contributes to the enhancement of catalytic performance of the Fenton reaction. The defective surface not only exposes more Mo(IV) active sites for rapid Fe3+/Fe2+ conversion but also promotes cooperation with H2O2 molecules for reactivation. This synergistic effect brings about enhanced reaction kinetics and boosts the decomposition of H2O2, which causes the molybdenite co-catalytic system to display an efficient removal rate for various organic pollutants. This work unveils the defects’ contribution for catalyzing the Fenton reaction and sheds light on the potential large-scale water treatment use cases for abundant high-defect molybdenite materials.

Severe conditions involved in hydrogen storage and transportation limit the practical applications of hydrogen denitration reaction. In this paper, we developed a new process that consists of methanol steam reforming inline hydrogen production coupled with denitration, which reduces the threshold use of hydrogen. The bifunctional CuZnOx–X–MnPdOz@Ni catalyst prepared in this paper could achieve inline hydrogen production through the CuOx center and reduce NOx by the MnPdOz center. The optimal CuZnOx–CeZrOy–MnPdOz@Ni candidate catalyst could maintain over 90% denitration efficiency under conditions: GHSV = 22 000 h−1 + nmethanol : nwater = 1 : 1.3 + 800 ppm NO at 150 °C. We conducted various characterization methods to reveal the valence state distribution of the promising catalyst. The experimental results indicated that the inline hydrogen selective catalytic reduction of NO is a promising strategy for green, efficient, and sustainable NOx control technology.