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Ultrasmall nitrogen-doped carbon-coated CoSe2/ZnSe nanospheres (CoSe2/ZnSe@C nanospheres) are fabricated by direct selenization of a delicately designed Co1.6Zn0.4-(benzimidazole)4 metal–organic framework (MOF) nanosheet precursor and used as the anode materials in sodium-ion batteries (SIBs). The fabricated CoSe2/ZnSe@C nanospheres deliver a remarkable rate performance (395 mAh g−1 at 0.1 A g−1 and 341 mAh g−1 at 5.0 A g−1) and excellent long-term durability (346 mAh g−1 after 2500 cycle at 2.0 A g−1). The superior Na storage performance of the fabricated CoSe2/ZnSe@C nanospheres could be mainly attributed to their ultrasmall particle sizes and the phase boundaries between CoSe2 and ZnSe, which improve the kinetics of the electrode, relieve the volume change during the charge/discharge process, and provide extra Na+ storage sites. This work opens up possibilities to fabricate metal selenide–based hybrid materials with desired nanostructures and compositions from rationally designed multimetal MOF precursors for high-performance anode materials in SIBs.

Application of nitrogen-doped carbon for electroreduction of CO2 to CO receives increasing attentions, and improving the CO selectivity of carbon-based materials is prominent. Here we introduce a halogen-assisted calcination strategy for constructing two-dimensional (2D) nitrogen-doped carbon from ZIF-8 precursor. Benefitting from the abundant graphitic-N (G-N) and the enlargement of electrochemical surface area (ECSA), 2D nitrogen-doped carbon presents excellent catalytic activity with the high faradaic efficiency (FE) of CO reaching 99.5% and current density of −2.6 mA cm−2 at a low potential of −0.5 V (vs. RHE) in H-type cell, with the long-term stability up to more than 20 h. A positive correlation between FECO and the ratio of G-N (the ratio of graphitic-N content to total N content.) is revealed. The halogen-assisted calcination can effectively increase the G-N ratio and enlarge ECSA, thereby increasing FECO, which is a promising strategy for improving CO selectivity of carbonaceous materials.

Sliding wear-induced nanolayering and its positive impact on wear resistance have been observed in conventional binary alloys with a matrix of high stacking fault energy (SFE), but this concept has never been reported in high-entropy alloys (HEAs) with low SFE. Here, we design and fabricate a (CoCrFeNi)90Ag10 HEA, consisting of a face-center-cubic (fcc) CoCrFeNi HEA matrix with low SFE and uniformly dispersed Ag precipitates. In comparison with CoCrFeNi, a significant reduction in friction and wear was found in (CoCrFeNi)90Ag10 HEA through the spontaneous formation of nanolayered subsurface microstructure during wear. The finding suggests a novel approach for designing HEAs that can achieve low friction and wear.

Public smog reduction behavior is vital for controlling smog pollution. The study investigates the factors that influence individuals’ willingness to enact smog reduction behavior. The hypothetical...

The development of organic nanoparticles that fluoresce in the near-infrared, especially in the second near-infrared (NIR-II) window, improves in vivo fluorescence imaging due to deeper penetration and higher spatiotemporal resolution. We report two kinds of NIR-II fluorescent molecules with twisted intramolecular charge-transfer (TICT) and aggregation-induced emission (AIE) characteristics. The virus-like particles (VLPs) of simian virus 40 (SV40) were used as templates to encapsulate the molecules in a well-defined structure (referred to as CH1-SV40 and CH2-SV40). The CH1-SV40 dots exhibited a highly uniform size of 21.5 nm, strong fluorescence, high photostability, and good biocompatibility in vitro and in vivo. Their fluorescence spectrum exhibited a peak at 955 nm, with a tail extending to 1200 nm. Moreover, the CH1-SV40 dots, with a quantum yield of 13.03%, enabled blood vessel imaging and image-guided surgery with a high signal-to-background ratio. Overall, the hybrid nanoparticles represent a new kind of NIR-II AIE nanoprobes for biomedical imaging.

The creep behavior of Fe–17Cr–1.2Cu–0.5Nb–0.01C ferritic heat-resistant stainless steel was investigated at temperatures ranging from 973 to 1123 K and stresses from 15 to 90 MPa. The evolution of precipitates after creep deformation was analyzed by scanning electron microscopy, energy dispersion spectrum, and transmission electron microscopy. The minimum creep rate decreased with the decrease in the applied load and temperature, thereby extending the rupture life. Cu-rich phase and Nb-rich Laves particles were generated in dominant quantities during the creep process, and the co-growth relationship between them could be detected. Creep rupture was featured by ductile fracture with considerable necking. As increasing the temperature and decreasing the stress, the softening of the metal matrix was accelerated, showing more obvious plastic flow. The true stress exponent and activation energy were 4.9 and 375.5 kJ/mol, respectively, indicating that the creep deformation was dominated by the diffusion-controlled dislocation creep mechanism involving precipitate-dislocation interactions. Based on the creep rupture data obtained, the Monkman–Grant relation and Larson-Miller parameter were established, which described the creep rupture life for the studied steel well.

Elevated levels of reactive oxygen species (ROS) are implicated in the onset and progression of many diseases, e.g., virus infection, ischemic stroke and neurodegenerative diseases. ROS-scavenging nanomaterials have attracted particular interest. Here, we report the development of a natural protein nanocage named Dps for in vitro and in vivo antioxidant treatment by inhibiting the Fenton reaction, a critical step in ROS generation and interconversion. Systematic surface engineering enabled cell penetration, good colloidal stability, and facile purification of Dps. With its intrinsic ferroxidase activity consuming both H2O2 and Fe2+, Dps not only protects human cells from oxidative stress but also effectively alleviates ROS-induced inflammation in a mouse dermatitis model. The protection is triggered by elevated H2O2 and thereby, in principle, avoids ROS imbalances. Thus, Dps has potential as a new bionano platform for different purposes, such as antiaging, anti-inflammation and cosmetics.

In this paper, a novel Dy2O3-Al2O3-SiO2 (DAS) glass ceramic was designed and prepared for joining zirconia toughened alumina (ZTA) ceramic. The crystallization, thermal expansion behavior and wetting behavior of the DAS glass filler were studied. The effect of cooling rate and joining temperature on the microstructure and flexural strength of joints was investigated. The results show that slow cooling rate (15 °C/min) leads to crystallization of brazing seam, which causes the formation of pores in the joints due to the large density difference between the glass and the crystalline phases. The dissolution of ZrO2 from ZTA substrate into the filler during joining process improves the mismatch of the coefficient of thermal expansion (CTE) between the brazing seam and substrate. The maximum flexural strength of 535 MPa is obtained when the joining temperature and cooling rate are 1475 °C and 50 °C/min, respectively.

PV power production is highly dependent on environmental and weather conditions, such as solar irradiance and ambient temperature. Because of the single control condition and any change in the external environment, the first step response of the converter duty cycle of the traditional MPPT incremental conductance algorithm is not accurate, resulting in misjudgment. To improve the efficiency and economy of PV systems, an improved incremental conductance algorithm of MPPT control strategy is proposed. From the traditional incremental conductance algorithm, this algorithm is simple in structure and can discriminate the instantaneous increment of current, voltage and power when the external environment changes, and so can improve tracking efficiency. MATLAB simulations are carried out under rapidly changing solar radiation level, and the results of the improved and conventional incremental conductance algorithm are compared. The results show that the proposed algorithm can effectively identify the misjudgment and avoid its occurrence. It not only optimizes the system, but also improves the efficiency, response speed and tracking efficiency of the PV system, thus ensuring the stable operation of the power grid.

The face-centered-cubic (fcc) CoCrFeMnNi high-entropy alloy suffers from low strength and wear resistance at ambient temperature. Herein, we developed a strategy to overcome the strength/ductility trade-off and simultaneously increase the wear resistance via the in situ formation of uniformly dispersed Mn3O4 nanoparticles in an ultrafine-grained fcc FeMnNi matrix. The obtained equiatomic FeMnNi alloy exhibited a high yield strength of up to 912 MPa and an elongation of 19 pct. Grain boundary and oxide-dispersion-strengthened were found to be the main strengthening mechanisms. Ball-on-disk wear tests showed that the FeMnNi alloy had low wear rates in the order of 10−4-10−5 mm3/(N m) upon sliding against an alumina ball, and the wear mechanism changed from abrasive wear to oxidation and fatigue wear at high loads and sliding velocities. The presence of Mn3O4 nanoparticles hindered the severe plastic flow of the fcc matrix during sliding. The excellent combination of strength, ductility, and tribological performance of the present alloy renders it as a promising candidate for structural applications.

Titanium alloys have been widely used for medical devices and structural applications. However, conventional titanium alloys often suffer from low resistance to wear, particularly at elevated temperatures. Herein, an equiatomic TiMoNb compositionally complex alloy (CCA) is shown to exhibit wear resistance comparable to alumina at room temperature (RT). Even at 600 °C, the alloy still shows an extremely low wear rate of the order of 10−6 mm3/(N·m). The remarkable wear resistance is achieved via tuning the interfacial structure and chemistry in TiMoNb CCA, including nanostructuring, titanium segregation at the grain boundaries, and the formation of a high density of nanoscale coherent Ti-rich precipitates with cube-on-cube orientation relationship with the ultrafine-grained matrix. The present results provide significant insights into the design of novel alloys for service in harsh environments.

For drivers, traffic congestion causes enormous delays and increases energy consumption. For a city’s traffic management team, traffic congestion challenges economic growth and increases pollution....

It is becoming more crucial nowadays for researchers to objectively utilize reasonable and effective methods to choose a key customer index and analyze a wealth of data, with the aim of setting up ...

Two-dimensional (2D) metal–organic frameworks (MOFs) and their derivatives with excellent dimension-related properties, e.g. high surface areas, abundantly accessible metal nodes, and tailorable structures, have attracted intensive attention as energy storage materials and electrocatalysts. A major challenge on the road toward the commercialization of 2D MOFs and their derivatives is to achieve the facile and controllable synthesis of 2D MOFs with high quality and at low cost. Significant developments have been made in the synthesis and applications of 2D MOFs and their derivatives in recent years. In this review, we first discuss the state-of-the-art synthetic strategies (including both top-down and bottom-up approaches) for 2D MOFs. Subsequently, we review the most recent application progress of 2D MOFs and their derivatives in the fields of electrochemical energy storage (e.g., batteries and supercapacitors) and electrocatalysis (of classical reactions such as the HER, OER, ORR, and CO2RR). Finally, the challenges and promising strategies for the synthesis and applications of 2D MOFs and their derivatives are addressed for future development.

The development of nonprecious metal-nitrogen-carbon (M-N-C) materials with efficient metal utilization and abundant active sites for the oxygen reduction reaction (ORR) is of great significance for fuel cells and metal-air batteries. Ultrasmall 2 D Cox Zn2-x (benzimidazole)4 [Cox Zn2-x (bim)4 ] bimetallic metal-organic framework (MOF) nanosheets (≈2 nm thick) are synthesized by a novel bottom-up strategy and then thermally converted into a core-shell structure of sub-5 nm Co nanodots (NDs) wrapped with 2 to 5 layers of Co,N-codoped graphene (Co@FLG). The size of the Co NDs in Co@FLG could be precisely controlled by the Co/Zn ratio in the Cox Zn2-x (bim)4 nanosheet. As an ORR electrocatalyst, the optimized Co@FLG exhibits an excellent half-wave potential of 0.841 V (vs. RHE), a high limiting current density of 6.42 mA cm-2 , and great stability in alkaline electrolyte. Co@FLG also has great ORR performance in neutral electrolyte, as well as in Mg-air batteries. The experimental studies and DFT calculations reveal that the high performance of Co@FLG is mainly attributed to its great O2 absorptivity, which is endowed by the abundant Co-Nx and pyridinic-N in the FLG shell and the strong electron-donating ability from the Co ND core to the FLG shell. This elevates the eg orbital energy of CoII and lowers the activation energy for breaking the O=O/O-O bonds. This work sheds light on the design and fabrication of 2 D MOFs and MOF-derived M-N-C materials for energy storage and conversion applications.

CaO–Al2O3–SiO2–TiO2 glass ceramic filler with high crystallinity was used for joining alumina ceramic. The influence of joining temperature and crystallization treatment on the microstructure and flexural strength of joints was studied. The results demonstrated that a joining temperature higher than the melting temperature of crystals was essential to obtain dense joints. Furthermore, the formation of CaAl2Si2O8 at the alumina/glass filler interface decreased the flexural strength of joints due to the mismatch of coefficient of thermal expansion (CTE) between CaAl2Si2O8 and substrate. The maximum flexural strength of 256 MPa at room temperature was achieved when the joining temperature was 1260 °C. After crystallization treatment, a large number of fine CaTiSiO5 was precipitated in the brazing seam. The flexural strength of joints after crystallization at room temperature was 221 MPa, and increased to 242 MPa at 800 °C. These results can be attributed to the change of CTE value of the brazing seam.

Global climate change and human activities have resulted in immense changes in the Earth’s ecosystem, and the interaction between the land surface and the atmosphere is one of the most important processes. Wind is a reference for studying atmospheric dynamics and climate change, analyzing the wind speed change characteristics in historical periods, and studying the influence of wind on the Earth-atmosphere interaction, additionally, studying the wind, contributes to analyzing and alleviating a series of problems, such as the energy crisis, environmental pollution, and ecological deterioration facing human beings. In this study, data from 697 meteorological stations in China from 2000 to 2019 were used to study the distribution and trend of wind speed over the past two decades. The relationships between wind speed and climate factors were explored using statistical methods, furthermore, combined with terrain, climate change, and human activities, we quantified the contribution of environmental factors to wind speed. The results show that a downward trend was recorded before 2011, but overall, there was an increasing trend that was not significant, moreover, the wind speed changes showed obvious seasonality and were more complicated on the monthly scale. The wind speed trend mainly increased in the western region, decreased in the eastern region, was higher in the northeastern, northwestern, and coastal areas, and was lower in the central area. Temperature, bright sunshine duration, evaporation, and precipitation had a strong influence, in which wind speed showed a significant negative correlation with temperature and precipitation and vice versa for sunshine and evapotranspiration. The influence of environmental factors is diverse, and these results could help to develop environmental management strategies across ecologically fragile areas and improve the design of wind power plants to make better use of wind energy.

Tumor targeting with nanoparticles is a promising strategy for cancer diagnosis and treatment, especially for drug delivery to solid tumors. Previous studies mainly focused on nanoparticle design to improve their targeting efficiency, but few have investigated the impact of tumor progression stages on the targeting efficiency. Here, we used PEGylated viral nanoparticles (VNPs) of bacteriophage P22 to explore the relationship between targeting efficiency and tumor progression stages using a colorectal cancer model. We found an 8.1-fold increase in the accumulation of P22 VNPs systematically injected 7 days after tumor inoculation compared with those injected 21 days after tumor inoculation. Most tumor-targeted P22 VNPs were concentrated in tumor-associated macrophages in the tumor blood vessels, the density of which decreased with the progression of tumors. These results reveal that the tumor targeting efficiency of P22 VNPs decreased with tumor progression. These findings provide valuable information for not only the understanding of controversial observations regarding targeted cancer therapy in experimental and clinical studies but also the design of nanoparticle-based tumor targeting probes or therapeutics.

The effects of polycarboxylate superplasticizers (PCEs) on the dispersing properties and initial hydration of cement particles with various water-to-cement (w/c) ratios was investigated, including the water film thickness (WFT), rheology, fluidity, adsorption of PCEs, zeta potential, degree of hydration, hydration products. The experimental results demonstrate that the initial rheological and fluidity parameters were more sensitive to the PCE dosage at a lower w/c because the WFT and the zeta potential on cement particles change more significantly. Moreover, the higher adsorption amounts of the PCEs at a lower w/c lead to a stronger inhibition of the initial hydration, whilst, at the same PCE dosage, the cement pastes have a more rapid fluidity loss and quicker hydration reactions at a higher w/c due to a lower adsorption amount of the PCE on cement particles.

The non-Hermitian skin effect (NHSE) in non-Hermitian lattice systems depicts the exponential localization of eigenstates at system's boundaries. It has led to a number of counter-intuitive phenomena and challenged our understanding of bulk-boundary correspondence in topological systems. This work aims to investigate how the NHSE localization and topological localization of in-gap edge states compete with each other, with several representative static and periodically driven 1D models, whose topological properties are protected by different symmetries. The emerging insight is that at critical system parameters, even topologically protected edge states can be perfectly delocalized. In particular, it is discovered that this intriguing delocalization occurs if the real spectrum of the system's edge states falls on the same system's complex spectral loop obtained under the periodic boundary condition. We have also performed sample numerical simulation to show that such delocalized topological edge states can be safely reconstructed from time-evolving states. Possible applications of delocalized topological edge states are also briefly discussed., Comment: 9 pages, 8 figures, comments are welcome

Direct electrochemical reduction of CO2 to multicarbon products is highly desirable, yet challenging. Here, we present a potentiostatic pulse-electrodeposition of high-aspect-ratio CuxAuy nanowire arrays (NWAs) as high-performance electrocatalysts for the CO2 reduction reaction (CO2RR). The surface electronic structure related to the Cu:Au ratio in the CuxAuy NWAs could be facilely modulated by controlling the electrodeposition potential and the as-fabricated CuxAuy NWAs could be directly used as the catalytic electrode for the CO2RR. The morphology of the high-aspect-ratio nanowire array significantly lowers the onset potential of the alcohol formation due to the diffusion-induced enhancement of the local pH and CO concentration near the nanowire surface. Besides, the properly adjusted surface electronic structure of the CuxAuy NWA enables the adsorption of CO and facilitates the subsequent CO reduction to ethanol via the C-C coupling pathway. Owing to the synergistic effect of morphology and electronic structure, the optimized CuxAuy NWA selectively reduces CO2 to ethanol at low potentials of −0.5–−0.7 V vs. RHE with a highest Faradaic efficiency of 48%. This work demonstrates the feasibility to optimize the activity and selectivity of the Cu-based electrocatalysts toward multicarbon alcohols for the CO2RR via simultaneous adjustment of the electronic structure and morphology of the catalysts.

Lead halide perovskite quantum dots (PQDs) have recently been proposed as scalable and color-tunable single emitters, but their slow spontaneous emission (1–10 ns) creates a mismatch with high-spee...

In the present work, wetting behaviour of Ag–Cu eutectic filler on high nitrogen austenitic stainless steel (HNS) and 316L austenitic stainless steel (316L) base metals was firstly studied using a sessile drop method in high vacuum. The Ag–Cu eutectic filler exhibits completely different dynamic wetting process on the surface of HNS and 316L. The equilibrium contact angle of Ag–Cu/HNS system is lower and its wetting time is shorter than that of Ag–Cu/316L system. Subsequently, brazing experiments were carried out for HNS and 316L base metals using the same filler at 840 °C for a holding period of 5–30 min under high vacuum. Microstructural analysis shows that the 316L/316L joints are composed of α-Cu and fine Ag–Cu eutectic. The HNS/HNS joints consist of β-Ag and coarse Ag–Cu eutectic. The optimal shear strength of HNS/HNS joints (290 MPa) is significantly higher than that of 316L/316L joints (175 MPa) because of the formation of diffusion layer. Therefore, HNS has tremendous potential to take the place of the traditional austenitic stainless steels for industry application.

Purpose The purpose of this paper is to frame an empirical model with the priority of implementing soft critical successful factors (CSFs) of total quality management (TQM) in Chinese manufacturing companies. Design/methodology/approach In total, 23 hypotheses regarding the relationships among TQM factors and business results have been developed through literature review and are tested using the structural equation modelling (SEM). The data used in this study are collected from 228 manufacturing companies in the central area of China. Findings Of the 23 hypotheses, 11 were statistically significant, and according to the empirical results a conceptual framework complying to Chinese condition is constructed and discussed in the finding parts to group soft CSFs of TQM into different levels of importance. Research limitations/implications Researchers can use the framework to further study soft CSFs of TQM in detail, and extend it to explore their impact mechanism for a clearer and deeper understanding of the TQM. Practical implications The empirical framework for soft CSFs of TQM provides a new perspective for managers to implement the soft CSFs and optimise the quality management system of their manufacturing companies. Originality/value This research uses multiple, distinct indicators for each soft factor to test an elaborate SEM model of the relationships among them, according to the empirical results constructs a holistic framework classifying the importance level of soft CSFs of TQM, which is novel and subjected with Chinese condition and manufacturing characteristics.

Although dilute Cu-Cr alloys are frequently used for applications involving sliding contacts, their wear mechanism at elevated temperatures has rarely been explored. We fabricated a bulk Cu-6 wt pct Cr alloy using high-energy ball milling and spark plasma sintering, and systematically investigated its dry sliding wear behavior against 440C stainless steel at room temperature and 300 °C. The alloy had a heterogeneous microstructure consisting of coarse-grained Cu (average grain size: 1.5 µm) distributed into a nanocrystalline Cu-Cr matrix (average Cu grain size: 77 nm; Cr-rich precipitate size: 18 nm), which gave high strength and plasticity (ultimate compressive strength: 1020 MPa; strain-to-failure: 26.0 pct) at room temperature. At 300 °C, the strength was significantly reduced, the coefficient of friction and wear rate increased, and the dominant wear mode switched from adhesive wear to oxidative/abrasive wear. Uniformly distributed nanoscale Cr-rich and Cr oxide precipitates hindered severe plastic deformation near the sliding surface during wear at room temperature; at 300 °C, severe plastic deformation was observed, with elongated Cu grains and uniformly dispersed Cr-rich and Cr oxide nanoparticles. Formation of a discontinuous glaze layer consisting of equiaxed nanograins of Cu, Cu oxides, and Cr oxides resulted in severe abrasion-assisted wear, and reduced the wear resistance at 300 °C.

A kind of n–p (SnO2)1.3/(α ∼ Bi2O3)x/(β ∼ Bi2O3)1−x nanocomposite (SB-15) was synthesized with polyvinyl alcohol (PVA) as a template by solid state synthesis. XRD and HR-TEM confirmed the formation of n–p (SnO2)1.3/(α ∼ Bi2O3)x/(β ∼ Bi2O3)1−x. Particle size is found to be about 18 nm from HR-TEM images. FE-SEM clearly detected the boundary between SnO2 nanoparticles and Bi2O3 polyhedron particles. The special morphology and coexisting of α-Bi2O3 and β-Bi2O3 in SB-15 make it have a stronger visible light absorption range as far as 725 nm. PL and photocurrent test shows that the SB-15 has the best photocarriers separation capability. About 99% decolorization ratio of Rh.B was achieved in only 5 min. About 70% Cr6+ was degraded within 20 min and it is about 60% for tetracycline in the coexisting system (Te with Cr6+ solution), introducing it as a promising photocatalytic material. This work has addressed the method of phase-selective synthesis of n–p SnO2/α ∼ Bi2O3/β ∼ Bi2O3 by convenient solid state synthesis, which should be useful for the studies of other composites.

It is important to evaluate the utilization pathways of biomasses as there are different multiple choices for various types of biomasses. A method using the functional exergy efficiency as a unified protocol is proposed to evaluate the effectiveness of energy utilization in three utilization pathways of biomasses: pyrolysis, oxygen gasification and anaerobic digestion. The results show that straws are more suitable than manures used in the pyrolysis process. Functional exergy efficiencies of the oxygen gasification process of six biomasses are all higher than those of the pyrolysis process. The functional exergy efficiencies of the manures have increased, becoming close to those of straws. For the anaerobic digestion process, the functional exergy efficiencies of straws are generally lower than that of manures. Manures with low lignin content (chicken manure in this study) are more suitable as the feedstock of anaerobic digestion process. The functional exergy efficiencies of anaerobic digestion are lower than those of the pyrolysis and gasification processes while the temperature exceeds 850 °C.

The shrinkage of inland lakes has become a major problem in arid region. Human activities are competing for water resources with sustainable lake ecosystem. Considering improving irrigation efficiency does not help on water saving at basin scale and reducing ET through mulching, zero tillage and deficit irrigation will lead to crop yield loss, this study proposed an alternative way that returning cropland to lake to achieve the balance between endorheic lake restoration and human water consumption. The approach consists of four procedures: (1) identifying the target annual inflow (Qtar) of endorheic lake; (2) calculating available consumable water (ACW) in the upstream based on Qtar; (3) setting ET deduction goals using water consumption balance approach; (4) estimating crop area to be deducted. This approach is implemented at Ebinur Lake of China under two restoration scenarios (lake area restored to 522 km2 and 800 km2). The results indicate that to restore the Ebinur Lake to 522 km2, the annual inflow should be increased to 602.6 × 106 m³, and human water consumption should be reduced by 320.3 × 106 m³. If the restoration goal of Ebinur Lake is set to 800 km2, an annual inflow of 876.6 × 106 m³ is required, and the human water consumption should be reduced by 594.2 × 106 m³. The over-expansion of cropland and artificial forest is found to be the main reasons for the shrinkage of Ebinur Lake. Finally, the feasible solutions for ecosystem restoration of Lake Ebinur are provided for both scenarios. The methodology adopted in this research can be applied to the restoration of other inland lakes in arid regions.

The existing approaches that deal with undesirable outputs tend to either increase the efficiency scores of DMUs or keep the efficiency scores constant and do not allow undesirable outputs to achie...

This study establishes a dynamic model of a new brake system with two-layer structure to explore the mechanism of vibration and noise reduction of a brake pad with new structure. The model is used to analyze the effects of parameters of the double-layer pad on the stability and stick-slip vibration characteristics of the brake system. The stability of the brake system is optimized by brake parameters with respect to the stability diagram of brake pressure under a relatively wide range. System vibration modes can be changed from period-doubling bifurcation to chaos based on the variation of brake pressure and the parameters of double-layer pad via numerical analysis. The chaotic vibration region is optimized in this study using the correlation coefficient, which consists of friction-layer pad mass mb2 and connection stiffness k2. Results show that the range of chaotic vibration region can be reduced when the friction-layer pad mass and connection stiffness are large.

Low-frequency/resonance magnetoelectric interactions and power conversion efficiency of magnetoelectric gyrators consisting of compositionally-graded nickel zinc ferrites and lead zirconate titanate with a coil wound around it were proposed and systematically characterized. Grading-induced differences of magnetic moment and remnant magnetization in ferrites with composition of Ni1−xZnxFe2O4 (0 ≤ x ≤ 0.3) can create the desired built-in field to decrease the required bias. The samples were characterized in terms of magnetostriction, low-frequency/resonance and power conversion efficiency with varieties of Zn concentrations, reversal sequence and volume ratio. A maximum PE of 62.9% was achieved in the composite of PZT-NiFe2O4-Ni0.9Zn0.1Fe2O4 at H = 10 Oe with volume ratio n = 0.5 under load RL = 700 Ω. With contribution of the desired built-in field, maximum PE of 60% under zero bias was also achieved in similar conditions. These favorable features open up the possibilities of ME gyrators with grading for promising applications in power electronics, converters and wireless energy harvesters without a sacrifice in device volume and modest rise in magnetomechanical efficiency.

Herein, we report an ethanothermal synthesis of multicolor fluorescent carbon dots (CDs) by using a series of phenols and oxidants as the precursors. The emission colors of CDs are well-controlled at blue, green, yellow or red wavelengths by adjusting the combination of a phenol and an oxidant. And the naphthalenediol with highly reactivity and the oxidant with heavy halogen atom result in CDs exhibiting long wavelength emission. The resulting nanodots are characterized as amorphous aggregates with abundant oxygen species. The phenol-derived CDs can be used as highly processible fillers to fabricate epoxy composites, and a white light-emitting diode (LED) employing the multicolor CDs/epoxy composite as the light converter is also demonstrated.

The development of techniques for monitoring the gasotransmitter carbon monoxide (CO) at the subcellular level is significant for elucidating its diverse cellular functions. Herein, a mitochondria-targetable, colorimetric and far-red fluorescent probe FR-CO is presented for tracking CO levels in the mitochondria of living cells. The FR-CO probe can sensitively detect CO using a turn-on fluorescence spectroscopic method, with a detection limit of around 38.9 nM. Additionally, the FR-CO probe exhibits outstanding selectivity towards CO over other various bioactive molecules. Moreover, the obvious color change (from colorless to pink) of the probe makes it possible to visually detect CO in aqueous solution. Most importantly, the excellent response properties of the FR-CO probe enable its application in the tracking of fluctuations in the CO levels of mitochondria in living cells, and it is thus anticipated that this probe will be a novel tool for further investigating the biological functions of CO in subcellular mitochondria.

In this study, eight 1-alkyl-2,3-dimethylimidazolium ionic liquids are analysed by X-ray photoelectron spectroscopy. The effect of both the anion and the cation on the electronic environment of cationic nitrogen regions is explored. It concludes that the cationic N 1s binding energy shifts to the lower value when the basicity of the anion increases or the acidity of the cation decreases. The impact of the cation acidity on the cation-anion interactions is demonstrated systematically by carefully comparing the binding energies of anion-based components for each anion. It is found that for more basic anions, the charge-transfer effect between counterions can be effectively shielded; for less basic anions, such an effect is negligible. The charge shielding effect of the alkyl substituent is also studied by using dodecyl-based ionic liquids, compared to 1-alkyl-3-methylimidazolium analogues. It suggests that long alkyl substituents can have a significant electron donating effect to the cation headgroup and thus effectively shield the charge-transfer effect between cations and anions.

Gate-induced ion flow through 2D layered graphene oxide membranes has been reported. The applied isolated gate voltage allows for notable control over sub-nanometer confined ionic current as a function of gate polarity and gate electrode location.

This empirical study evaluated the public acceptance of nuclear-power plants in China. A conceptual framework was proposed to explain the factors affecting nuclear-power acceptance based on anteced...

Photon enhanced thermionic emission (PETE) is a new concept in solar energy conversion, combining thermal and photovoltaic carrier excitations with thermionic emission. A solar-power-driven thermionic energy converter operates by illuminating the solar light condensed by a large-scale Fresnel lens to convert heat energy into electrical energy. By enhancing the efficiency of converting solar radiation into the emitter internal energy, the output power and efficiency of the thermionic energy converter can be greatly improved. In this study, using numerical simulations, the effects of emitter temperature and output characteristics on a thermionic energy converter were investigated. The results showed that the higher rate of the heating power represented the higher temperature of an emitter, as well as output current density, and efficiency. In addition, by reducing the diameter of a collector and thermal conductivity of insulation materials, or increasing the diameter of emitter, the temperature of emitter, output current density, and efficiency could be notably improved. It is also worth mentioning that the main factor that affected the emitter temperature in the process of heat transfer was heat conduction between solids. In conclusion, adequate illumination, reasonable size of collector and emitter, as well as appropriate insulation measurements could efficiently improve the output characteristics of thermionic energy converter.

To ensure the photovoltaic (PV) system can still output maximum power under changing environmental conditions, a modified hill climbing algorithm is proposed. The algorithm uses a variable step-size strategy to reduce the steady-state oscillations and prevent operating point from diverging away from the maximum power point by introducing boundary conditions. To verify its effectiveness, the proposed algorithm is compared with the conventional and adaptive hill climbing method under the environmental condition of irradiance step change and gradual change. The simulation results show that the proposed algorithm can increase the dynamic response speed of the PV system by 75% under varying irradiance, and can achieve a steady-state tracking accuracy of 99.8%. Besides, the proposed algorithm only needs to embed several lines of additional programs in the conventional hill climbing maximum power point tracking (MPPT) control program and does not require additional hardware components, which reduces the cost of PV power generation.

A thermal network model is developed to study the performance of a solar thermal-powered heating, cooling and hot water system comprised of evacuated tube collectors, a latent heat thermal energy storage unit and related heat exchangers, and an absorption chiller/heat pump. The system performance is studied for a residential building in a hot climate zone (Phoenix, Arizona) on two typical solar days representative of a relatively cold day and a relatively hot day. A systematic sizing methodology is presented to minimize the phase change material mass and the output temperature fluctuations. An exergy analysis is also performed to quantify the second law efficiency of the system. Analysis of the energy performance of the system shows that more than 80% annual energy saving can be achieved by using a solar collector area of 10 m2 coupled with a 29 kWh latent heat thermal energy storage system. The effect of the heat transfer design of the thermal energy storage system, in particular the number of condenser pipes of the input heat pipe and evaporator sections of the output heat pipes embedded within the phase change material, on the thermal and exergetic performance of the system is also investigated. It is shown that increasing the number of pipes decreases the temperature fluctuations and increases the exergy efficiency due to minimized temperature drops. Quantitatively, increasing the number of pipes from 60 to 112, decreases the maximum temperature drops across the latent heat thermal energy storage system from about 30 °C to 15 °C, and increases the exergy efficiency from about 75% to 90%. This study demonstrates the capability of a solar thermal-powered heating, cooling and hot water system integrated with latent heat thermal energy storage to significantly reduce the auxiliary energy input needed to meet the demands of a residential building located in a hot climate zone.

Poor osteogenesis and implant-associated infection are the two leading causes of failure for dental and orthopedic implants. Surface design with enhanced osteogenesis often fails in antibacterial activity, or vice versa. Herein, a surface design strategy, which overcomes this trade-off via the synergistic effects of topographical micropatterning and a bilayered nanostructured metallic thin film is presented. A specific microgrooved pattern is fabricated on the titanium surface, followed by sequential deposition of a nanostructured copper (Cu)-containing tantalum (Ta) (TaCu) layer and a pure Ta cap layer. The microgrooved patterns coupled with the nanorough Ta cap layer shows strong contact guidance to preosteoblasts and significantly enhances the osteogenic differentiation in vitro, while the controlled local sustained release of Cu ions is responsible for high antibacterial activity. Importantly, rat calvarial defect models in vivo further confirm that the synergy of microgrooved patterns and the Ta|TaCu bilayered thin film on titanium surface could effectively promote bone regeneration. The present effective and versatile surface design strategy provides significant insight into intelligent surface engineering that can control biological response at the site of healing in dental and orthopedic implants.

Floquet higher order topological insulators (FHOTIs) are a novel topological phase that can occur in periodically driven lattices. An appropriate experimental platform to realize FHOTIs has not yet been identified. We introduce a periodically-driven bipartite (two-band) system that hosts FHOTI phases, and predict that this lattice can be realized in experimentally-realistic optical waveguide arrays, similar to those previously used to study anomalous Floquet insulators. The model exhibits interesting phase transitions from first-order to second-order topological matter by tuning a coupling strength parameter, without breaking lattice symmetry. In the FHOTI phase, the lattice hosts corner modes at eigenphase $0$ or $\pi$, which are robust against disorder in the individual couplings., Comment: 5+ pages for the main text, plus 7 pages for the Supplementary Materials, to be submitted to Phys. Rev. B

This research paper presents recent work exploring the power of natural language processing (NLP) methods applied to qualitative engineering education data. As NLP and other machine learning methods are developed for qualitative data, it is important to prioritize the role that theory plays in rigorous qualitative research, where the selection of a theoretical framework serves as the lens by which the research project is framed, results are analyzed, and findings are brought to light. Indeed, the view from a different theoretical lens can highlight novel or new findings. In this work, we seek to explore the viability of NLP methods for helping researchers select appropriate frameworks. In this work, we present our method to train a Python-based NLP algorithm to analyze an existing data set of interview data using one theoretical lens: Community of Practice theory, an oft-used theory in graduate education literature, which is the topic of the interview corpus to investigate. We present and test two methods for developing dictionaries by which to train the algorithm: An expert-curated dictionary and a machine-generated dictionary compiled by mining the theoretical framework sections of published literature employing Community of Practice theory. We apply these two dictionaries to analyze a corpus of 54 interview transcripts investigating graduate engineering attrition. The high dimensional data from NLP can be compared using Principal Component Analysis (PCA) visualization and pairwise distance plots to determine which method results in the most well-defined structure indicating agreement between the dictionary and the corpus of interview transcripts. In the discussion, we highlight opportunities for using these automated methods to help researchers with qualitative data analysis and warn against potential dangers and ethical ramifications for using machine learning and NLP for social science data. This work will have impact on the disciplinary communities working to embed computational language-based methods into engineering education research, and for the qualitative methods communities across social science and education disciplines.

Self-assembled virus-like particles (VLPs) hold great potential as natural nanomaterials for applications in many fields. For such purposes, monodisperse size distribution is a desirable property. However, the VLPs of simian virus 40 (SV40), a representative VLP platform, are characterized by polymorphism. In an attempt to eliminate the polymorphism, 15 mutants of the VLP subunit (VP1) are constructed through the substitution of double cysteines at the VP1 pentamer interfaces, generating a group of VLPs with altered size distributions. One of the mutants, SS2 (L102C/P300C), specifically forms homogenous T = 1-like tiny VLPs of 24 ± 3 nm in diameter. Moreover, the stability of the SS2 VLPs is markedly enhanced compared with that of wild-type VLPs. The homogeneous self-assembly and stability enhancement of SS2 VLPs can be attributed to the new disulfide bonds contributed by Cys102 and Cys300, which are identified by mass spectrometry and explored by molecular dynamics simulations. Endocytosis inhibition assays indicate that SS2 VLPs, like the polymorphic wild-type VLPs, preserve the multipathway feature of cellular uptake. SS2 VLPs may serve as an evolved version of SV40 VLPs in future studies and applications. The findings of this work would be useful for the design and fabrication of VLP-based materials and devices.

The exotic topological states have advanced the exploration for topological characteristics, such as invariant topological orders and band inversion. Here, we experimentally construct photonic dimer chains composed of split-ring resonators to exhibit interesting topological properties with different orientation angles. By using the method of near-field detection, we measure the dispersion relation and sublattice pseudospin vectors of different orientated configurations, which immediately determines the associated winding number of bulk bands as the topological invariant. Moreover, the sublattice pseudospin vector inversion observed at band edges indicates the band inversion and the associated topological phase transition, which is reconfirmed by measuring the band-edge mode parity and symmetry of the split-ring resonator cell. Our results not only directly show the topological winding number, band inversion, pseudospin, and the symmetries of band-edge states in experiments, but also reveal the great potential of the split-ring resonator platform to experimentally explore the advanced topological characteristics, such as higher winding numbers or higher Chern numbers in more complex setups.

Topological corner modes (TCMs) can exist in two-dimensional square lattices with either quantized dipole moments or a quantized bulk quadrupole moment. In both cases, four TCMs, each localized at one corner, can be found degenerate at zero energy. Here, we analytically show that in finite-sized systems, adjacent TCMs can couple, with hopping strength and sign determined by the edge configuration, which is directly associated with the magnetic flux of the unit cell. Consequently, we found that the response functions of the coupled corner modes of different origins, i.e., quantized edge dipoles and a quantized bulk quadrupole, possess distinctive line shapes. The response functions can therefore be used as a hallmark to determine the corner modes' nature. We verify our findings in simulations using phononic crystals.

The isothermal oxidation behavior of 17Cr-0.85Si-0.5Nb-1.2Cu ferritic stainless steel in air was studied from 850°C to 1050°C by analyzing its weight gain after oxidation. The kinetic curves were plotted using the oxidation weight-gain data, and the structure, surface morphology, and element distribution of the oxide films were analyzed by XRD, SEM, and EDS. The results showed that the oxidation kinetics curves at 850°C and 950°C followed a parabolic law, and a continuous and dense oxide film composed of Cr2O3 and MnCr2O4, FeCr2O4, and Cu-Cr rich spinel was formed, which reveals that the steel displayed good oxidation resistance. When the temperature was increased to 1050°C, the oxidation kinetics curves gradually changed from parabolic to linear after 40 h exposure, which indicated that the oxidation resistance significantly worsened. A lower oxidation resistance was observed at 1050°C due to the formation of a large amount of Fe2O3 on the surface and the volatilization of the inner Cr2O3 layer.

To investigate the use of saliency-map analysis to aid in searches for transient signals, such as fast radio bursts and individual pulses from radio pulsars. We aim to demonstrate that saliency maps provide the means to understand predictions from machine learning algorithms and can be implemented in piplines used to search for transient events. We have implemented a new deep learning methodology to predict whether or not any segment of the data contains a transient event. The algorithm has been trained using real and simulated data sets. We demonstrate that the algorithm is able to identify such events. The output results are visually analysed via the use of saliency maps. We find that saliency maps can produce an enhanced image of any transient feature without the need for de-dispersion or removal of radio frequency interference. Such maps can be used to understand which features in the image were used in making the machine learning decision and to visualise the transient event. Even though the algorithm reported here was developed to demonstrate saliency-map analysis, we have detected, in archival data, a single burst event with dispersion measure of $41$\,cm$^{-3}$pc that is not associated with any currently known pulsar., Comment: 16 pages, 6 figures, accepted for publication in A&A

Ti-Cu alloys have attracted significant interests for use in dental and orthopedic implants because of excellent antibacterial activity. However, limited research efforts have been devoted to their sliding wear behavior. Herein, we have fabricated nearly fully dense ultra-fine-grained Ti-Cu alloys with the Cu contents of 5 and 25 at. pct using a combination of high energy ball milling and spark plasma sintering (SPS) and systematically investigated their microstructure, mechanical properties, and sliding wear behavior. The results show that the Ti95Cu5 alloy consists of Ti2Cu precipitates uniformly distributed in an α-Ti matrix. This particular microstructure results in excellent mechanical properties, including a compressive yield strength of up to 1593 MPa, compressive strength of over 2400 MPa, and fracture strain of up to 26.8 pct. Conversely, the bulk Ti75Cu25 alloy consists mainly of Ti2Cu with a small amount of α-Ti and exhibited a slightly higher yield strength but reduced compressive strength and fracture strain. The hardness and yield strength of the Ti-Cu alloys were approximately three times and one order of magnitude higher, respectively, than those of commercially pure Ti. Sliding wear tests reveal that the wear mechanism of the ultra-fine-grained Ti-Cu alloys is distinct from that of CP-Ti and that the wear resistance is enhanced with increasing Ti2Cu content.

The influence of fillers composition on microstructure, the physical and chemical properties of joints is studied. Thermal mismatch between fillers and Al2O3 liners during laser joining process could be effectively reduced with the increase of MgO content. The mutual diffusion and the substitution reaction lead to the formation of the eutectic spinel phase (Mg, Fe)Al2O4. The interfacial atomic diffusion is enhanced by the addition of MgO. The joints corresponding to fillers composed of 70 wt.% Al2O3-15 wt.% MgO-15 wt.% SiO2 have the optimal mechanical performance. The average flexural strength of joints reaches 168 Mpa which is 80% of the Al2O3 liner (200Mpa). The weight loss of the joint interlayer in 10 wt.% HCl (pH = 0.45) for 24 h is 0.62 mg/cm2 which is 0.16 mg/cm2 lower than that of the liner. The softening temperature of joint interlayer exceeds 1500 °C. The reliability of Al2O3-lined joints could be maintained during the sequential process of arc welding for outer steel pipe layers. The corrosion of pipe layers could be effectively avoided.

Sunshine duration is an important indicator of the amount of solar radiation received in a region and an important input parameter for the study of atmospheric energy balance, climate change, ecosystem evolution, and social sustainability. Currently, extrapolation and interpolation of data from meteorological stations are the most common methods used to calculate sunshine duration on a regional scale. However, it is difficult to obtain high precision sunshine duration in areas lacking ground observation or where sunshine duration is highly heterogeneous on the ground. In this paper, a new method is proposed to estimate sunshine duration with hourly total cloud amount (CTA) data from sunrise to sunset derived from the Fengyun-2G geostationary meteorological satellite (FY-2G). This method constructs a new index known as daytime mean total cloud coverage amount and provides quadratic equations relating daytime mean total cloud coverage amount to relative sunshine duration in different seasons. The method was validated with ground observation data for 2016 from 18 meteorological stations in the Three-River Headwaters Region of Qinghai Province, China. For individual stations, the coefficient of determination (R2) between estimated and measured sunshine was at least 0.894, the RMSE (root mean square error) was 0.977 h/day or less, the MAE (mean absolute error) was 0.824 h/day or less, the RE (relative error) was 0.150 or lower, and the value of d was 0.963 or greater, which validated that the proposed method can effectively predict daily sunshine duration. These equations can also provide higher precision estimates of regional-scale sunshine duration. This was demonstrated by comparing, for the entire study region, the spatial distribution of sunshine duration estimated from season-based equations with results from three different interpolation methods based on ground observations. Overall, the study confirms that total cloud amount measures from a geostationary satellite can be used to successfully estimate sunshine duration.