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A UV-curable high refractive index resist (nD = 1.7063) for UV-nanoimprint lithography is synthesized and the refractive index can be further improved to 1.7327 after baking. 50 nm resolution patterns are faithfully imprinted into the resist film.

A three-dimensional (3-D) model for multispecies vacuum arc considering ionization and recombination process has been built in this article. With the model, the arc behaviors and species characteristics subjected to actual spatial magnetic fields of cup-shaped axial magnetic field (AMF) contact and transverse magnetic field-axial magnetic field (TMF-AMF) contact are investigated and compared. Furthermore, the validity of the model is verified by comparing with the experiments. Simulation results show that contact structures affect the species distributions of the arc by changing magnetic field and current density distributions. More triple charged ions are generated through ionization under higher electron temperature so that the triple charged ions gather where current constricts. The heat flux density is large in the current contraction region, where the contribution from triple charged ions is large as well. Spatial magnetic field distribution affects the Lorentz force acting on ion components. The force distribution is relatively uniform and the species are subject to inward force on the arc edge under cup-shaped AMF contact. For TMF-AMF contact, the double charged ions are subject to the force pointing to the TMF contact arms, whereas the triple charged ions are subject to the force pointing to the arc center. In addition, the consideration of arc species can improve the accuracy of the simulation results of the heat flux distribution, leading to a good agreement of the erosion condition between experiments and simulation.

Machined surface roughness will affect parts’ service performance. Thus, predicting it in the machining is important to avoid rejects. Surface roughness will be affected by system position dependent vibration even under constant parameter with certain toolpath processing in the finishing. Aiming at surface roughness prediction in the machining process, this paper proposes a position-varying surface roughness prediction method based on compensated acceleration by using regression analysis. To reduce the stochastic error of measuring the machined surface profile height, the surface area is repeatedly measured three times, and Pauta criterion is adopted to eliminate abnormal points. The actual vibration state at any processing position is obtained through the single-point monitoring acceleration compensation model. Seven acceleration features are extracted, and valley, which has the highest R-square proving the effectiveness of the filtering features, is selected as the input of the prediction model by mutual information coefficients. Finally, by comparing the measured and predicted surface roughness curves, they have the same trends, with the average error of 16.28% and the minimum error of 0.16%. Moreover, the prediction curve matches and agrees well with the actual surface state, which verifies the accuracy and reliability of the model.

In the chemical looping with oxygen uncoupling (CLOU) process, CuO is a promising material due to the high oxygen carrier capacity and exothermic reaction in fuel reactor but limited by the low melting point. The combustion rate of carbon is faster than the decoupling rate of oxygen carrier (OC). Hence, high temperature tolerance and rapid oxygen release rate of CuO modified by three different ores were investigated in this study. The kinetics analysis of oxygen decoupling with Cu-based oxygen carriers was also evaluated. Results showed that CuO modified by chrysolite had faster oxygen release rate than that of CuO. Limestone showed obvious positive effect on the oxidization process. The selected OCs could keep stable in at least 20 cycles, for about 1200 min. Shrinking core model (SCM) fitted well for the decoupling process in the temperature range of 1123–1223 K. Reduction rate kinetic information may aid in the development of chemical looping with oxygen uncoupling (CLOU) technologies during reactor design and process modeling. Ternary doped copper oxide with chrysolite and limestone could improve the reactivity of CuO in decoupling and coupling process and also improve the high temperature tolerance.

Block polymers (BPs) potentially can be used to template large arrays of nanopatterns for advanced nanotechnologies. However, the practical utilization of directed BP self-assembly typically requires guide patterns of relatively small size scales. In this work, the macroscopic alignment of block polymer cylinders on a template-free substrate is achieved through raster solvent vapor annealing combined with soft shear (RSVA-SS). Spatial control over nanoscale structures is realized by using a solvent vapor delivery nozzle, poly(dimethylsiloxane) shearing pad, and motorized stage. Complex patterns including dashes, crossed lines, and curves are demonstrated, along with the ability for large area alignment and scale-up for industry applications. The unique ability to directly write macroscopic patterns with microscopically aligned BP nanostructures will open new avenues of applied research in nanotechnology.

It is of a great challenge to apply nonmetal fractions (NMFs) of waste printed circuit boards (WPCBs) as reinforcing fillers in rubbers. In this paper, a typical amorphous synthetic rubber, ethylene propylene terpolymer (EPDM), is used as the model material to investigate the mechanical properties of EPDM/NMFs composites. A multifunctional grafting monomer containing two thiol groups and two carboxyl groups is designed and synthesized. The monomer is used to synthesize highly grafted EPDM-g-AA via melt grafting. Tensile strength of EPDM/NMFs composite sharply increases to 18 MPa when 10phr of EPDM-g-AA is used. The grafted polymer also significantly improves the thermal oxidation resistance. It can be expected that the strategy is able to be expanded to other rubber systems and opens the door to application of NMFs in rubber industry.

To obtain the lightweight, high strength, and high damping capacity porous NiTi alloys, the microwave sintering coupled with the Mg space holder technique was employed to prepare the porous NiTi alloys. The microstructure, mechanical properties, phase transformation behavior, superelasticity, and damping capacity of the porous NiTi alloys were investigated. The results show that the porous NiTi alloys are mainly composed of the B2 NiTi phase with a few B19′ NiTi phase as the sintering temperature is lower than or equal to 900 °C. With increasing the sintering temperature, the porosities of the porous NiTi alloys gradually decrease and the compressive strength increases first, reaching the maximum value at 900 °C, and then decreases. With increasing the Mg content from 1 wt.% to 7 wt.%, the porosities of the porous NiTi alloys increase from 37.8% to 47.1%, while the compressive strength decreases from 2058 to 1146 MPa. Compared with the NH4HCO3 space holder, the phase transformation behavior of the porous NiTi alloys prepared with Mg space holder changes, and all of the compressive strength, superelasticity, shape memory effect and damping capacity are greatly improved.

The impacts of ammonia gas (NH3) plasma treatment on the performance and positive gate bias stress (PGBS) of polycrystalline-silicon (poly-Si) junctionless thin-film transistor (JL-TFT) are studied. A −0.785-V threshold voltage ( $V_{\mathrm {TH}}$ ) shift of JL-TFT due to the NH3 plasma treatment is observed, which is attributed to the fixed oxide charge effect of the plasma-induced interfacial layer (PIL). In addition, the transconductance of JL-TFT with the NH3 plasma treatment is enhanced by ~2.73 times due to the trap state passivation of grain boundaries in the poly-Si, and the ON-state current ( $I_{\mathrm {ON}}$ ) is enhanced by ~2.91 times. In addition to the performance enhancement of JL-TFT by the plasma process, the $V_{\mathrm {TH}}$ shift of poly-Si JL-TFT under PGBS is suppressed from −0.240 to −0.063 V after the plasma treatment. It is attributed to the less degradation of insulator/channel interface due to the growth of PIL by the plasma process. Moreover, the $I_{\mathrm {ON}}$ degradation of JL-TFT after PGBS is also improved from −19% to −16% after the plasma treatment. As the carrier transport of JL-TFT is the bulk conduction rather than the surface conduction of conventional inversion-mode TFT, the degradation of insulator/channel interface would exhibit less impacts on the $I_{\mathrm {ON}}$ . The improvement of performance and PGBS of JL-TFT by the NH3 plasma treatment would be beneficial to the application of 3-D integrated circuits.

Over the past decade, two typical device architectures of perovskite solar cells (PSCs) have been developed as n–i–p regular devices (r-PSCs) and p–i–n inverted cells (i-PSCs). Hole-transporting materials (HTMs) play a vital role in facilitating hole extraction and transport in PSCs. However, a large number of reported HTMs are only applicable for either r-PSCs or i-PSCs owing to the quite different design strategies of the corresponding HTMs. Herein, a spiro-structured configuration was employed to construct lower symmetry molecules. Planar electron-rich carbazole and twisted triphenylamine units as electron donors were incorporated into the spiro-core and denoted as spiro-CZ and spiro-TPA, respectively. The decreased symmetrical conformation contributes to high glass transition temperatures and supports thermally stable amorphous HTM films. Compared with spiro-TPA, spiro-CZ featuring carbazole donors realized more effective capability of hole extraction. As a result, a high power conversion efficiency (PCE) of 16.52% was achieved by n–i–p structured PSCs with spiro-CZ, significantly exceeding that of the reference spiro-TPA (8.47%). However, contrary to expectations, p–i–n structured PSCs with undoped spiro-CZ and spiro-TPA obtained a comparable PCE of 16.06% and 15.79%, respectively. Note that these PCEs were shown to outperform that of commercial dopant-free spiro-OMeTAD (10.48%) and PEDOT:PSS (13.74%) under the same conditions. Moreover, the doped spiro-CZ-based r-PSCs delivered a good long-term device stability under ambient conditions. Overall, seeking lower symmetry molecules endowed with planar electron-rich units is a promising method to support the development of efficient universal HTMs toward i-PSCs and r-PSCs.

The explored p–i–n inverted architecture perovskite solar cells (i-PSCs) show promising application in flexible, large-scale and laminated photovoltaic technology. Polymeric HTMs for i-PSCs have been rarely reported. Thus far, only a commercial hole-transporting material, polytriarylamine (PTAA), has achieved a significant PCE of over 23% in i-PSCs. However, a perovskite precursor exhibits poor wettability on the PTAA films, thereby reducing their reproducibility and causing uncontrollable device instability. In this study, a type of binaphthyl-ether based polymer Z13 was developed through radical polymerization to replace the palladium catalyzed coupling reaction. A small molecule (Z5) and commercial PTAA were classified as the control. The comparatively flexible ether bond (–O–) of the backbone in Z13 improved the solubility and film forming properties of the material, thereby contributing to a superior morphology uniformity of the deposited perovskite. Consequently, promising device performance was achieved for i-PSCs endowed with Z13. The maximum power conversion efficiency of 18.80% obtained for Z13 was comparable with that of PTAA (19.02%), exceeding that with Z5 (18.48%). More importantly, Z13 films ensured a significantly optimized device thermal-durability as opposed to references PTAA and Z5. This study proposed a promising design for novel polymeric materials with low costs, high production reproducibility, favorable solubility and excellent optoelectronic properties.

In this article, the model including cathode spot process and deuterium desorption process on zirconium deuterium cathode is developed. Five kinds of particle fluxes on cathode surface and three mechanisms affecting deuterium diffusion in cathode are considered. The model not only describes the deformation of cathode metal, but also describes the variation of deuterium concentration with time. On pure zirconium cathode, the mean charge state is larger but on zirconium deuterium cathode, the total ion number density is larger since there are additional deuterium ions, and simulation results show the discharge currents are very close on the two cathodes, the energy flux density on ZrD0.66 cathode is larger so cathode spot crater develops faster on ZrD0.66 cathode. Ablation rates caused by different mechanisms are calculated and the results show in cathode spot development process, mass loss caused by evaporation is ignored, most of the liquid metal will resolidify on cathode surface, and droplets are the main reason for cathode ablation. The ablation rates due to the ejection of droplets are close to experimental results. The ratios of deuterium ion from different mechanisms in this process are also calculated and it is 93.5% in simulation. Simulation results are in agreement with the other researchers’ works.

Temperature showed obvious effect on the reaction rate and conversion when CuO was used as an oxygen carrier (OC), in which in situ gasification chemical-looping combustion (iG-CLC) occurred at low...

Hot-carrier stress (HCS) characteristics of polycrystalline-silicon (poly-Si) tunnel field-effect thin-film transistors are investigated and compared with the conventional poly-Si thin-film transistors (TFTs). After HCS with ${V}_{{\text {DS}}} = {2}{V}_{{\text {GS}}} = {20}$ V for 1000 s, poly-Si TFT exhibits significant ON-state current ( ${I}_{{\text {on}}}{)}$ degradation ~85% and two-step subthreshold swing (SS) behavior due to the serious lattice damage between the pinch-off point and the drain. For the poly-Si tunnel field-effect transistor (TFET), less ${I}_{{\text {on}}}$ degradation ~70% is observed. In addition, the stress drain voltage ( ${V}_{{\text {DS}}}$ ) effect of the HCS is also studied. When the stress ${V}_{{\text {DS}}}$ is increased from 10 to 15 V, the poly-Si TFETs exhibit more obvious stressed ${I}_{{\text {on}}}$ degradation (~24.4%) than that of poly-Si TFTs (~6.5%). When the stress ${V}_{{\text {DS}}}$ is further increased from 15 to 20 V, the poly-Si TFETs exhibit less stressed ${I}_{{\text {on}}}$ degradation (~62.4%) than that of poly-Si TFTs (~85%). Because the increase in the stress drain voltage is dropped in the pinch-off region of the poly-Si TFETs after the pinch-off phenomenon occurs, resulting in less impact on the stress field at the tunnel junction. When the channel length is decreased, the results show that the HCS effect of poly-Si TFETs is insensitive to the channel length, and the poly-Si TFTs show more serious electrical degradation and breakdown behavior with the scaling down of the channel length. The stronger HCS immunity of poly-Si TFETs would be an important advantage to replacing poly-Si TFTs for applications of 3-D integrated circuits.

It is usually deformed severely for thin-walled workpiece when the fixture is removed after machining, which is mainly caused by the redistribution of internal stress and machining induced residual stress (MIRS). Previous works have tried to relax the fixture in-processes to release the residual stresses (i.e. internal stress and MIRS), and perform the following machining operation after re-fasten the workpiece at its totally relaxed state. However, the totally relaxed state is only an equilibrium of residual stresses and the MIRS on the top layer of the workpiece will be changed after the following machining process. The residual stresses of the workpiece become imbalance again and thus will lead to the deformation of final component. In this paper, a novel research work of actively controlling the in-processes deformation of thin-walled part is presented, which is aimed at balancing the internal stress/MIRS and preventing the redistribution of residual stresses after last machining step. Firstly, the variations of internal stress, MIRS and clamping force during machining are analyzed through a simplified in-process model of blade. An equilibrium equation is established by taking the residual stresses as the equivalent loads of clamping point. Next, to achieve the proposed in-processes active control method, a mathematical model of how to actively adjust the fixture between machining operations is established. And then, the finite element method (FEM) is used to calculate the MIRS induced deformation, in which the MIRS is measured through experiment. A prototype of active control fixture for blade part is developed to adjust the in-process deformation. Finally, three groups of machining experiments on a simplified blade with three different treatments on the fixture after the rough machining – no relaxing the fixture at all, totally relaxing the fixture in-process, and actively controlling the deformation in-process– are carried out. The validation demonstrates that the proposed in-process active control method could decrease machining deformation significantly. The maximum deformation reduced to 18.3 % and 42.9 % compare to the no relaxing and totally relaxing the fixture after rough milling.

In this paper, the performance degradation of reinforced-concrete (RC) columns with corroded longitudinal steel bars was experimentally investigated. Ten large-scale RC column specimens were constructed, and the longitudinal steel bars were corroded, to simulate the real severe environmental condition that concrete structures may encounter during their long-term service life, using a hybrid method. All specimens were tested under lateral cyclic loadings up to failure with the aim of revealing the effects of rebar corrosion level and axial compression ratio on the seismic behaviour of corroded RC columns. Test results indicate that an increase in the rebar corrosion level and axial compression ratio causes a marked degradation in the seismic performance of corroded RC columns, especially a reduction in the strength, ductility and energy dissipation capacity. To study the effect of the rebar corrosion level, the seismic damage indices of the corroded RC columns were also assessed using the damage model proposed by Park–Ang. In addition, a strength prediction method for corroded RC columns was proposed based on the modified compression field theory coupled with the conventional sectional analysis method. The proposed prediction method was then verified with the experimental results.

Regenerative chatter can easily occur in the milling process of thin-walled workpiece due to the inherently low stiffness. This article aims to predict the stability of thin-walled workpiece in the milling process with a complete dynamic model. First, multiple structural modes of thin-walled workpiece are taken into consideration, and a complete dynamic model of thin-walled workpiece milling system is developed. Then, a numerical integration method is used to achieve the stability lobe diagrams of the milling system and identify the chatter frequency. Besides, the major structural mode, which is responsible for the occurrence of thin-walled workpiece chatter in the milling process, is predicted. A series of milling tests concerning a general cantilever plate are conducted, and the test results agree well with the predicted results, which shows the effectiveness of the proposed method. Finally, the effects of milling tool and structural modes on milling stability are discussed separately, which could provide theoretical basis for the dynamic modeling of thin-walled workpiece in milling process.

This effort is to improve CuO’s chemical-looping characteristics by introducing iron ore, chrysolite and limestone to obtain high power efficiency in chemical looping combustion (CLC) power plants. The reactivity and oxygen uncoupling behavior were evaluated by thermogravimetric analysis (TGA) in N2 and CO2 atmosphere under different heating rate. CuO modified by chrysolite and limestone showed better performance than iron ore-added CuO oxygen carrier (OC) in a CLC system. CO2 could play an important role in the gasification of char only when the temperature is above 800 °C. Two peaks were found in the Differential thermal gravity (DTG) curve when modified CuO reacted with char. That could be the solid-solid reaction turned into gas-solid reaction with temperature increasing. Scanning electron microscopy (SEM)/energy-dispersive X-ray (EDX) technique analysis indicated an enhancement of high temperature tolerance of Cu-based OCs, while CuO occurred sever sinter and agglomeration. Higher temperature tolerance means higher temperature off-gas from the fuel reactor entering the heat utilization power generation system, which could obtain higher efficiency in CLC power plants.

As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of water hammer effect and the theory of multiphase flow. With this model, the transient flow of gas well can be simulated by segmenting the curved part of tubing and calculating numerical solution with the method of characteristic curve. The results show that the higher the opening coefficient of the valve when closed, the larger the peak value of the wellhead pressure, the more gentle the pressure fluctuation, and the less obvious the pressure mutation area will be. On the premise of not exceeding the maximum shut-in pressure of the tubing, adopting large opening coefficient can reduce the impact of the pressure wave. The higher the cross-section liquid holdup, the greater the pressure wave speed, and the shorter the propagation period will be. The larger the liquid holdup, the larger the variation range of pressure, and the greater the pressure will be. In actual production, the production parameters can be adjusted to get the appropriate liquid holdup, control the magnitude and range of fluctuation pressure, and reduce the impact of water hammer effect. When the valve closing time increases, the maximum fluctuating pressure value of the wellhead decreases, the time of pressure peak delays, and the pressure mutation area gradually disappears. The shorter the valve closing time, the faster the pressure wave propagates. Case simulation proves that the transient flow model of gas well can optimize the reasonable valve opening coefficient and valve closing time, reduce the harm of water hammer impact on the wellhead device and tubing, and ensure the integrity of the wellbore.

Synthesis of cyclic, semicrystalline, and recyclable polythiourethanes was realized via the catalyst-free zwitterionic alternating copolymerization of N-alkyl aziridines with carbonyl sulfide (COS)...

The effects of rolling deformation on the interface bonding strength and microstructure of bimetallic clad plates were simulated. The composition and sub-structure of the interface were analyzed by electron probe micro-analyzer (EPMA) and transmission electron microscope (TEM). The results showed that the interfacial bonding strength of clad plates was significantly depend on the deformation process, and the bonding time was also a significant factor on bonding effect apart from total strain in the two-stage rolling. Chromium, nickel and other alloying elements have a significant diffusion zone at the bonding interface with a diffusion width of about 10µm. High resolution TEM analysis confirmed that there was an sound metallurgical bonding at the interface, and the structure of martensite in transition zone and matrix approximately meet the coherent relationship of(200) Ferrite // (111) Martensite and [020] Ferrite // [211]Martensite.

Polythiourethane is a promising heteroatom-containing polymeric material possessing outstanding properties such as high refractive index, biocompatibility, and good coordinating ability to heavy me...

In milling of thin-walled structures such as impellers or blisks, critical workpiece vibrations occur due to the excitation by the cutting forces and the dynamic interface between the workpiece and the fixture. Vibrations may cause instable state of the milling process, thus decreasing the production outcome by causing rejects. In respect to the milling process of thin-walled workpiece, a challenging task is to monitor the critical vibrations occurred in the workpiece itself or the contact surface between the workpiece and the clamping system. Vibrations can be reflected in the clamping system, and thus the clamping force variation monitoring is a potential scenario or solution to the challenging task. This article introduces a measurement prototype for the real-time dynamic clamping force monitoring. With respect to the measurement of clamping force, two case studies are carried out by a direct sensing method with PVDF thin-film sensors. In the first study, the measurement prototype with embedded PVDF sensors is located on the dynamometer, and an additional eddy-current transducer is applied for monitoring the workpiece deflection during the milling process. Deflection signals and cutting force signals from dynamometer are used as two referential signals to demonstrate the reliability of the prototype with embedded PVDF sensors. In the second study, milling test with the same tool and workpiece is implemented with only PVDF sensors monitoring. Dynamic clamping signal varying with different cutting durations in time, frequency, and time-frequency domain and different milling surface results is performed. Relationship between the collected signals and machining results is preliminarily analyzed. Case studies with thin-walled workpiece show the performance of the measurement prototype.

To improve the mechanical property of 2, 4-dinitroanisole (DNAN)/1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) melt-cast explosives, the effects of additives, N-methyl-4-nitroaniline(MNA), polyethyl...

Lanthanide (Ln) high-nuclearity clusters express charming structures and extensive potential applications; nevertheless, the progress of successfully obtaining Ln clusters is still untoward. Herein, two fascinating and classical 60-metal configurations were obtained based on mixed-lanthanide and solvothermal conditions, namely [Ln60(CO3)8(μ3-OH)96(H2dmp)24(Hdmp)12] Br12(NO3)8(CH3OH)x(H2O)y (abbreviated as mixed-Ln60; for compound 1, Ln60 = Eu52.7Gd7.3, x = 8, y = 43; for compound 2, Ln60 = Eu52.2Tb7.8, x = 15, y = 30; H2dmp− or Hdmp2− = 2,2-dimethylol propionic acid = L). The crystallographic study showed that the 60-metal core of compounds 1 and 2 are protected by a single type of organic ligand without any extra auxiliary ligand to complete the coordination sphere, which are the first to be reported in the containing Ln high-nuclearity clusters. Besides, the synthesis of 1 and 2 provides a practical way to obtain more analogues of Ln high-nuclearity clusters, featuring the original structure of the metal frame, which is expected to break the ionic radius limitation in the synthesis.

Pd-based nanocatalyst is a potential oxygen reduction oxidation (ORR) catalyst because of its high activity in alkaline medium and low cost. In this work, bimetallic PdAu nanocatalysts are prepared by one-pot hydrothermal method using triblock pluronic copolymers, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO19-PPO69-PEO19)(P123) as reducer and stabilizer, and heat-treatment method is applied to regulate catalyst structure and improve catalyst activity. The results show that the heat treatment can agglomerate the catalyst to a certain extent, but effectively improve the crystallinity and alloying degree of the catalyst. The ORR performance of the PdAu nanocatalysts obtained under different heat treatment conditions is systematically investigated. Compared with commercial Pd black and PdAu catalyst before heat treatment, the ORR performance of AuPd nanocatalyst obtained after heat treatment for one hour at 500 °C has been enhanced. The PdAu nanocatalysts after heat treatment also display enhanced anti-methanol toxicity ability in acidic medium.

We investigate the photogalvanic effect in nitrogen-doped monolayer molybdenum disulfide (MoS2) under the perpendicular irradiation, using first-principles calculations combined with non-equilibrium Green function formalism. We provide a detailed analysis on the behavior of photoresponse based on the band structure and in particular the joint density of states. We thereby identify different mechanisms leading to the existence of zero points, where the photocurrent vanishes. In particular, while the zero point in the linear photovoltaic effect is due to forbidden transition, their appearance in the circular photovoltaic effect results from the identical intensity splitting of the valance band and the conduction band in the presence of Rashba and Dresslhaus spin-orbit coupling. Furthermore, our results reveal a strong circular photogalvanic effect of nitrogen-doped monolayer MoS2, which is two orders of magnitude larger than that induced by the linearly polarized light.

Covalently linked π-stacked dimers represent the most significant platform for elucidating the relationship between molecular alignments and their properties. Here, we present the one-pot synthesis of two intramolecularly π-stacked dimers and disclose how intramolecular stacking modes dictate photoswitching properties. The dimer, which features cofacially stacked chromophores and geometrically favours intramolecular photochemical [2 + 2] cycloadditions, displays a nearly irreversible photoswitching behaviour. By contrast, the dimer, bearing crosswise stacked chromophores, is geometrically unfavourable for the cycloaddition and exhibits a highly reversible photoswitching process, in which the homolysis and reformation of carbon−carbon single bonds are involved. Moreover, the chiral carbon centres of both dimers endow these photoswitches with chirality and the separated enantiomers exhibit tuneable chiroptical properties by photoswitching. This work reveals that intramolecular stacking modes significantly influence the photochemical properties of π-stacked dimers and offers a design strategy toward chiral photoswitchable materials., Covalently bridged π-stacked dimers are excellent molecular platforms for understanding the relationship between stacking orientation and properties. Here, the authors synthesize a pair of π-stacked dimers that are aligned either cofacially or crosswise, allowing them to compare how the intramolecular stacking mode affects each dimer’s photoswitching properties.

As typical of sulfur-containing polymers, polythiourea is a promising polymeric material because of its outstanding properties such as self-healing, high refractive index, high dielectric constant,...

Beam-steering devices, which are at the heart of optical wireless broadcasting communication links, play an important role in data allocation and exchange. An ideal beam-steering device features large steering angles, arbitrary channel numbers, reconfigurability, and ultra-compactness. However, these criteria have been achieved only partially with conventional beam-steering devices based on waveguides, micro-electrical mechanical systems, spatial light modulators, and gratings, which would substantially limit the application of optical wireless broadcasting communication techniques. In this study, we designed and experimentally demonstrated an ultra-compact full-duplex meta-broadcasting communication system, which exhibits beam steering angles up to ±40°, 14 broadcasting channels with capacity for downstream and upstream links up to 100 and 10 Gbps for each user channel, three operating modes for flexible signal switching, and meta-device dimensions as small as 2 mm × 2 mm. In particular, the beam-steering meta-devices are mass-manufactured by a complementary metal-oxide-semiconductor processing platform, which shows their potential for large-scale commercial applications. The demonstrated meta-broadcasting communication system merges optical wireless broadcasting communications and metasurfaces, which reduces the complexity of beam-steering devices while significantly increasing their performance, opening up a new avenue for high-quality optical wireless broadcasting communications. This article is protected by copyright. All rights reserved.

This work investigates the transient arc behavior during the anode spot mode with CuCr25 electrodes theoretically and experimentally. In the simulation, a 2D transient magneto-hydro-dynamic (MHD) model considering multi-component plasma is used to calculate the arc parameters. Then, the energy flux is obtained to calculate the anode temperature in next time step. Simulation results show that when the anode temperature is high enough, the anode vapor density increases significantly. Therefore, ions from the cathode are decelerated by the anode vapor when arriving at the ionization layer, leading to changes in the ion temperature. Then, the arc current is more likely to flow to the edge of the atom vapor area instead of the anode center. Thus, the energy flux to the anode begins to heat the area around the anode spot, leading to a more uniform anode temperature distribution and a larger anode spot. The maximum anode temperature occurs after the peak current due to the thermal inertia. Experiments using optical methods for anode temperature determination are also conducted to verify the simulation results.

It is of great significance to study DC vacuum arc (DCVA) characteristics and anode thermal process in DC interruption based on artificial current zero method, which have great influence on the breaking performance of DC vacuum circuit breaker (DCVCB). In this paper, with the consideration of the effect of realistic magnetic field and hysteresis during the DC breaking process, the dynamic characteristics of DCVA and anode thermal process were simulated and analyzed. Firstly, a DCVA dynamic model is established under the commercial cup-shaped electrodes. The DCVA characteristics at seven different moments during the DC breaking process with a current falling frequency of 1kHz were simulated, which were combined to describe the dynamic characteristics of DCVA. The distribution of arc plasma’s parameters at seven different times, such as ion pressure and axial current density, was obtained by the simulation. Furthermore, a 2-D transient axisymmetric model of anode thermal process in DCVA is established. Through the numerical simulation, anode temperature distribution along radial and axial directions during the DC breaking process can be obtained.

Lead halide perovskite quantum dots have drawn worldwide attention due to their quantum confinement effect and excellent optical gain properties. It is worth noting that due to the toxicity of lead ions and the inherent instability of organic groups, research on all-inorganic lead-free metal halide perovskite quantum dots (ILFHPQDs) has become a hot spot in recent years. This paper summarizes the latest research progress of ILFHPQDs, analyzes the sources and limitations affecting the performance of ILFHPQDs, and provides the improvement methods. Firstly, the typical synthesis strategies of ILFHPQDs are discussed, followed by a focus on the structural characteristics, optoelectronic properties and stability of each type of ILFHPQD. Next, the applications of ILFHPQDs in devices are investigated. Finally, the challenges, solutions and future application directions of ILFHPQDs are prospected.

The structure-activity relationship between the morphology and composition of Pd-based nanocatalysts is an important fundamental issue in direct methanol fuel cells (DMFC). Three dimensional (3D) netlike Pd–Rh bimetallic catalysts with different atomic ratios (Pd1Rh3, PdRh, Pd3Rh1) are synthesized through a simple wet chemical way using P123 as a reducing agent and KBr as morphological regulator. The morphology, structure and composition of the catalysts are proved by a series of physicochemical test technology. It is shown that the 3D-netlike structure is composed of short self-assembly nanochains. Electrochemical results display that their application towards methanol oxidation reaction (MOR) in alkaline solution. The MOR activity of the optimized Pd3Rh1 nanocatalyst is improved to about 4.0 mA cm−2, which is much higher than that of the commercial Pd/C catalyst.

In this investigation, to reach a widely wavelength-selectable and stable single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser, the unpumped EDF-based saturable absorber (SA) and dual-ring structure are used simultaneously for thickly multi-longitudinal-mode (MLM) suppression. The dual-ring scheme can spread the operation range of gain medium from 1520.0 to 1580.0 nm only by using a C-band erbium-doped fiber amplifier (EDFA). Moreover, the dual-ring scheme and EDF-based SA also could suppress the MLM noise for SLM oscillation. In the tuning range, the Lorentzian 3 dB linewidth is also obtained between 15 and 22 kHz in the wavelength range.

Two novel dibenzothiophene-S,S-dioxide-based iridium complexes with yellow emission were fully synthesized and characterized. The photophysical, electrochemical and thermal properties, as well as electroluminescent properties of the resulting iridium complexes were discussed. Both the iridium complexes possess good thermal stability and high photoluminescence quantum yields. Also, we have successfully fabricated singly doped emissive layer (SDEL) hybrid white organic light-emitting devices (WOLEDs) using (3-PyFSO)2IrPic or (2-PyFSO)2IrPic as yellow-emitting phosphors and 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA) as host and blue-emitting fluorophor. The WOLEDs with (3-PyFSO)2IrPic show a maximal power efficiency (PE) of 4.28 lm/W at a brightness of 3.7 cd/m2 and a Commission Internationale de L'Eclairage (CIE) coordinates of (0.227, 0.260). Compared to (3-PyFSO)2IrPic, the WOLEDs based on (2-PyFSO)2IrPic exhibit a little better device's performances with a maximum PE of 4.70 lm/W at a brightness of 2.6 cd/m2 and a CIE coordinates of (0.244, 0.243).

Two kinds of ternary cobalt gold palladium (CoAuPd) and three kinds of binary AuPd alloy nanocatalysts are synthesized by co-reduction and successive reduction method. The CoAuPd nanocatalysts obtained by the successive reduction method possess a hollow structure with some solid nanospheres, nanodendrites and show much better catalytic activity for methanol oxidation reaction (MOR) (1.26 mA cm−2) than another CoAuPd NCs (1.14 mA cm−2) and binary AuPd nanocatalysts (0.85 mA cm−2). CO adsorption and electrochemical dealloying method can restructure nanocatalyst surface and improve MOR and oxygen reduction reaction (ORR) activities. Electrochemical dealloying reconstructs the hollow CoAuPd alloy to a CoAuPd@AuPd core-shell structure with pinholes and the dealloyed NCs exhibits better MOR (1.92 mA cm−2) and ORR (6.3 mA cmGEO−2) catalytic activities than the initial CoAuPd nanocatalysts (1.26 mA cm−2 for MOR and 3.4 mAcmGEO−2 for ORR). Accelerated durability tests (ADT) quantify the changes of stability before and after the surface reconstruction. The ternary CoAuPd nanocatalysts have excellent durability before and after surface reconstruction (current density decrease 14.04% for MOR and 0.3 mA cmGEO−2 for ORR) in alkaline medium.

To achieve wavelength-selectable and stable erbium-doped fiber (EDF) laser, a dual-Sagnac-ring configuration is designed to reach single-longitudinal-mode (SLM) oscillation and power-flattened output simultaneously. The presented and experimentally demonstrated EDF laser can also obtain the output power of 7.5 to 11.8 dBm in the continuous-wave (CW) tunability of 1523.0 to 1571.0 nm. Here, the power variation of lasing wavelength can be below than 1.0 dB over a wide working range of 1525.0-1565.0 nm for power-flattened output. Moreover, the 3-dB spectrum linewidth of presented EDF-based laser is measured in the range of 16.4-22.2 kHz via the Lorentzian fitting.

Storage technology of electrical energy with ultrafast charge/discharge rates is in high demand for future electronics and electric vehicles. Among them, sodium ion batteries (SIBs) have received much attention, however, the exploration of electrode materials with a high rate capacity and long cycle life still faces great challenges. In this work, we have fabricated coralloid NixCo1−xSe2 with a hierarchical architecture for the first time, and it presents specific capacities of 321 mA h g−1 after 2000 cycles at 2 A g−1, corresponding to a capacity decay rate of 0.011% per-cycle, and 277 mA h g−1 even at the high rate of 15 A g−1, which could be attributed to the enhanced conductivity by Co-doping, the hierarchical architecture preventing the structure from collapsing or crushing, the accelerated electron transmission and the shortened diffusion distance of Na+. The extremely fast electron and Na ion transfer kinetics could be associated with the capacitive contribution. We further reveal the ultrastable and ultrahigh rate Na-ion storage mechanism through systematic analysis including compositional/structure evolution studies and comprehensive electrochemical characterizations. The presented strategy for the design and synthesis of coralloid, Co doped NiSe2 with a hierarchical architecture could enlighten researchers on the development of electrodes with an ultralong cycle life and ultrahigh rate capability.

Here we report a facile synthesis of Pd@Rh core–shell nanocrystals with octahedral and cubic shapes. Under optimized conditions, Rh atoms can be deposited on Pd octahedral or cubic seeds in a layer-by-layer fashion to generate core–shell nanocrystals with a well-controlled shape. We then use CO oxidation as a probe to evaluate the catalytic performance of the core–shell nanocrystals with reference to a number of commercial catalysts. When supported on mesoporous silica, both the octahedral and cubic Pd@Rh nanocrystals show CO to CO2 conversion levels similar to that of a commercial Pt/Al2O3 catalyst while the two catalysts based on pure Rh (commercial Rh/C and Rh nanocubes/silica) needed much higher temperatures to reach the same level of conversion. In terms of ignition temperature, the Rh nanocubes show a value of 260 °C while those of the octahedral and cubic Pd@Rh nanocrystals are as low as 140 and 150 °C, respectively. Our results suggest that there is no significant difference between the octahedral and cubic Pd@Rh nanocrystals in terms of performance towards CO oxidation while both of them are advantageous over Rh nanocubes or Rh/C.

Carbon/Carbon (C/C) composite is a kind of material that has good mechanical property in environment with high temperature above 2000°C. Due to its low density, high specific modulus, high specific strength, high temperature resistance, ablation resistance and corrosion resistance, it has been successfully used for manufacturing parts used in the aero-engine or rocket parts. While fabricating this kind of composite material with the carbonization and graphitization process, porousness with different sizes will be left inside the material. These porousness will affect the milling process, which is a commonly used method for manufacturing the C/C composite parts. To address this problem, a mathematical model is developed to describe the distribution of the porousness inside the 2.5D C/C composite. Firstly, the machined section of the specimen is scanned with the high resolution optical scanning instrument and then transformed to an image. Secondly, the porousness inside the specimen is extracted to calculate their distribution and proportion. Finally, an exponential distribution model is found to be suitable for distribution of porousness inside the material and an algorithm for simulating the pore distribution is established. It is found that the simulated surface is in a good agreement with the measured surface, yielding a relative difference in predicted porosity of 19.6%. The pore distribution of simulated surface also conforms the exponential function distribution. Its coefficients are within the range of the real surface, which verifies the feasibility of the algorithm.

Four gneiss boulders on Holocene glaciofluvial fans offset by the Kongur normal fault in the Chinese Pamir Plateau were sampled to test the reliability and applicability of rock surface luminescence dating. The 10 Be ages of the boulders ranged from 2.1 to 7.5 ka. Depth profiles of luminescence intensity were measured using a modified multi-elevated-temperature post-infrared infrared stimulated luminescence (MET-pIRIR) protocol, in which two consecutive stimulations with different power, 15 and 131 mW/cm 2 , were performed for each temperature. The decay rate of the trapped charge at the surface σ φ 0 ¯ were calibrated using the 10 Be age for each boulder sample. The resulting values for the parameter σ φ 0 ¯ were utilized to estimate the exposure time of other samples. The shielding effect of rock varnish was examined in relation to the attenuation coefficient μ and the wavelength of the sunlight that penetrates a rock surface. Uncertainties in μ derived from fitting each MET-pIRIR signal depth profile, corresponding the parameter σ φ 0 t ¯ , and calculated ages were too large to allow precise comparisons to be made between vanished and unvarnished rock surfaces. The μ was assumed to be the same for all MET-pIRIR signals, and so was fitted simultaneously to all profiles derived from a single sample; this significantly reduces the fitting uncertainties in the parameters μ and σ φ 0 t ¯ . The long-term relative bleaching rate of the IR 50 , MET-pIRIR 110 , MET-pIRIR 170 and MET-pIRIR 225 signals were evaluated by comparing the ratios of σ φ 0 t ¯ derived from fitting of luminescence-depth profile. The IR 50 signal, MET-pIRIR 110 and MET-pIRIR 170 bleached tens, ∼5, and 2 times faster than the MET-pIRIR 225 signals, respectively. These results highlight the potential and challenges in using rock surface luminescence methods as a viable dating tool for exposure ages.

We have designed and synthesized two novel yellow phosphorescent iridium complexes using dibenzothiophene-S,S-dioxide-based cyclometalated ligand for the first time, which are capable of producing highly efficient yellow and white polymer light-emitting devices (PLEDs). The resulted iridium complexes display good thermal stability and high photoluminescence quantum yields. Both yellow and white PLEDs are fabricated with an identical single-emission-layer configuration of ITO/PEDOT:PSS/emission layer (EML)/CsF/Al. For the yellow phosphorescent PLEDs based on (p-CzFSOPy)2IrPic, the best device performances with a peak luminous efficiency (LE) of 13.3 cd/A and a peak external quantum efficiency (EQE) of 5.3% are achieved. More importantly, the two-element WPLEDs containing iridium (III)bis (2-(4,6-difluorophenyl)-pyridinato-N,C2′) picolinate (FIrpic) as blue and (p-CzFSOPy)2IrPic as yellow phosphors doped into a PVK:OXD-7 matrix at an appropriate ratio exhibited a maximum LE of 19.2 cd/A, a maximum EQE of 9.6%, an extremely high luminance of 18717 cd/m2 and Commission Internationale de L'Eclairage (CIE) coordinate of (0.317, 0.448). Moreover, at a luminance for practical application of 1000 cd/m2, the LE still remains as high as 19.0 cd/A, with a very slight decrease.

The effect of synergistic action of ultrasonic vibration and solidifi cation pressure on tensile properties of vacuum counter-pressure casting ZL114A alloys was studied systemically through testing and analyzing the tensile strength and elongation subjected to different ultrasonic powers and solidifi cation pressures. The results indicate that the synergistic action of ultrasonic vibration and solidifi cation pressure can result in the refi nement of grains and improvement of tensile properties. Both the highest tensile strength and elongation of aluminum alloy were obtained under synergistic action of 600 W ultrasonic power and 350 kPa solidifi cation pressure. Moreover, the tensile fracture morphology shows obvious ductile fracture characteristics. When the solidifi cation pressure is lower than 300 kPa, the effect of ultrasonic power on tensile strength and elongation is more obvious, but when the solidifi cation pressure is higher than 300 kPa, the effect of solidifi cation pressure on tensile strength and elongation is greater. Meanwhile, the size and morphology of the eutectic silicon were improved signifi cantly by the ultrasonic vibration and pressurized solidifi cation. The strip and massive eutectic silicon phase are completely converted into small short rod-like and evenly distributed Si phases at the grain boundary of primary α-Al.

In this paper, short carbon fiber-reinforced nylon (SCFRN) composites were fabricated using the fused deposition modeling (FDM) technology. In particular, different surface textures, namely convex squares and triangles, were created by using the printing method. It was found that fiber reinforcements could effectively enhance the load-carry capacity of the printed polymeric materials. Moreover, the tribological performance of SCFRN can be further improved with the surface textures. Microscopy observations revealed that the surface textures are particularly beneficial for the wear reduction by collecting hard wear debris such as broken fibers. The work has demonstrated that 3D printing technology has great potential for developing new wear-resistant engineering materials by controlling and creating desirable compositions and geometric structures/textures simultaneously.

In this study, using molybdenum sulfide (MoS2) as laser-sensitive particles and poly(propylene) (PP) as the matrix resin, laser-markable PP/MoS2 composite materials with different MoS2 contents ranging from 0.005 to 0.2% were prepared by melt-blending. A comprehensive analysis of the laser marking performance of PP/MoS2 composites was carried out by controlling the content of laser additives, laser current intensity, and the scanning speed of laser marking. The color difference test shows that the best laser marking performance of the composite can be obtained at the MoS2 content of 0.02 wt %. The surface morphology of the PP/MoS2 composite material was observed after laser marking using a metallographic microscope, an optical microscope, and a scanning electron microscope (SEM). During the laser marking process, the laser energy was absorbed and converted into heat energy to cause high-temperature melting, pyrolysis, and carbonization of PP on the surface of the PP/MoS2 composite material. The black marking from carbonized materials was formed in contrast to the white matrix. Using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and Raman spectroscopy, the composite materials before and after laser marking were tested and characterized. The PP/MoS2 composite material was pyrolyzed to form amorphous carbonized materials. The effect of the laser-sensitive MoS2 additive on the mechanical properties of composite materials was investigated. The results show that the PP/MoS2 composite has the best laser marking property when the MoS2 loading content is 0.02 wt %, the laser marking current intensity is 11 A, and the laser marking speed is 800 mm/s, leading to a clear and high-contrast marking pattern.

In practical applications, thin-walled parts require very precise assembly and positioning references, which means that high manufacturing accuracy is required. CNC machining is the main manufacturing technology for thin-walled aviation parts, and it is one of the key factors that determine the quality and efficiency of machining. Thin-walled parts have a complex structure, thin walls, weak rigidity and uneven distribution, making it very difficult to process.

In this study, the size of the titanium organic cage was controlled to achieve the restricted growth from a single Ag(I) atom (Ag@Ti5) to rare all-carboxylate-protected superatomic Ag cluster (Ag6@Ti6). The classical octahedral Ag64+ cluster with two delocalized electrons (2e) has been encapsulated in a Ti6 organic cage, which shows high stability in air and dimethyformamide (DMF). Furthermore, larger 2e nested double-tetrahedra Ag clusters (Ag86+ and Ag97+) protected using a tetrahedral hollow metalloligand framework (Ag8@Ti4 and Ag9@Ti4) were obtained. Electrospray ionization mass spectrometry (ESI-MS) and density functional theory (DFT) calculations confirmed that there are two delocalized electrons on these small Ag clusters. This study provides a new form of protection for superatomic Ag clusters and provides a feasible strategy for the development of stable Ag clusters.

As the main source of the vacuum arc plasma, cathode spots (CSs) play an important role on the behaviors of the vacuum arc. Their characteristics are affected by many factors, especially by the magnetic field. In this paper, the characteristics of the plasma jet from a single CS in vacuum arc under external axial magnetic field (AMF) are studied. A multi-species magneto-hydro-dynamic (MHD) model is established to describe the vacuum arc. The anode temperature is calculated by the anode activity model based on the energy flux obtained from the MHD model. The simulation results indicate that the external AMF has a significant effect on the characteristic of the plasma jet. When the external AMF is high enough, a bright spot appears on the anode surface. This is because with a higher AMF, the contraction of the diffused arc becomes more obvious, leading to a higher energy flux to the anode and thus a higher anode temperature. Then more secondary plasma can be generated near the anode, and the brightness of the ‘anode spot’ increases. During this process, the arc appearance gradually changes from a cone to a dumbbell shape. In this condition, the arc is in the diffuse mode. The appearance of the plasma jet calculated in the model is consistent with the experimental results.

The workpiece dynamics are an important factor in the planning of machining strategy. Usually, the structural dynamic parameters of workpiece are obtained by experimental modal analysis (EMA). However, the dynamics of thin-walled workpiece are varying due to material removal and tool-workpiece coupling. Operational modal analysis (OMA) provides a route to estimate the structural dynamic parameters during operation, but the input excitation of milling system is mainly periodic milling force, which violates the premise of OMA. In this paper, an output-only modal identification method for the dynamic parameters of thin-walled workpiece is proposed. The milling force is analyzed and the analysis results show the milling force contains white noise for OMA. However, strong harmonic components in milling force seriously interfere the identification of dynamic parameters. To remove the harmonic components in response signal, a revised least-squares (LS) method is proposed to fit harmonics with multiple fundamental frequencies. After the harmonic removal, OMA is conducted in frequency domain using the poly-reference least squares complex frequency (p-LSCF) method based on positive power spectral density (PSD). To verify the feasibility of the proposed method, the simulation case is conducted by exciting a 3-degree of freedom structure using measured milling force signal, and the results show a good agreement with the theoretical values both in frequencies and damping ratios. Furthermore, a series of milling tests under different cutting parameters are conducted on a thin-walled workpiece, where thin-film sensors are adopted to measure the structural response. The results show the method can be successfully applied to extract the workpiece dynamic parameters. Compared with results of EMA, the structural frequencies increase slightly, while the damping ratios show a large promotion due to the process damping.

The chemical looping co-gasification (CLCG) of rice husk and coal using iron ore as an oxygen carrier was carried out in a fixed bed reactor. The effects of different parameters including oxygen/carbon ratio, reaction temperature, steam flow rate, and rice husk blending ratio on the gasification performance were studied. Based on the carbon conversion efficiency, gasification efficiency, and gas yield, the optimal conditions of the CLCG of rice husk and coal were determined. Moreover, the synergistic effect in carbon conversion and syngas production between those two fuels was also analyzed. The results showed that the carbon conversion efficiency, gasification efficiency, and gas yield reached 88.16%, 49.23%, 1.14 Nm3/kg, respectively at the oxygen/carbon ratio of 0.2, the reactor temperature of 900 °C, the steam flow rate of 0.125 g/min, and the rice husk blending ratio of 50%. At this condition, there were significant synergistic effects between rice husk and coal during the CLCG process, and the synergistic rate for carbon conversion efficiency and gasification efficiency reached 21.54% and 3.62%, respectively. The SEM-EDX analysis showed that adding coal to rice husk could alleviate the ash deposition phenomenon on the surfaces of iron ore during the CLCG process.