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The engineering of switchable materials with controllable stimuli-responsive multistability remains challenging in materials science. Herein, we present syntheses and structural and magnetic studie...

Mg-6Gd-3Y-0.5Zr (VW63K) alloy is widely used in the aerospace field because of its excellent mechanical properties not only at room temperature but also under high service temperature. In this study, the effect of minor changes to the Y alloying levels on the hot tearing behavior of VW63K alloys was researched by using a "T" mold, with pouring temperature of 720 °C and mold temperature of 150 °C. The results show that the hot tearing susceptibility of the alloy decreases gradually with the increase of Y content from 2.8 to 3.4 wt%. The reason for this phenomenon is that high content of Y element narrows the susceptible freezing range and increases the eutectic liquid fraction of the alloy, which is helpful for the alloy to have a better compensation at the late stage of solidification and, thereby decreasing the hot tearing susceptibility.

We propose a method to quantitatively characterize the fine phase transition processes of Li+/Er3+:BaTiO3 (BLET) ferroelectric materials by observing fluorescence wavelength shift. A lithium and erbium co-doped barium titanate ferroelectric ceramic was fabricated and the down-conversion infrared fluorescence spectra of the transition 4I13/2 → 4I15/2 were measured as a function of temperature. The three structural phase transition processes, namely rhombohedral–orthorhombic, orthorhombic–tetragonal, and tetragonal–cubic transformations, determined by X-ray diffraction results are accompanied by corresponding changes in the position of the fluorescence peaks, yielding an exact consistency. This contactless, non-destructive and spatially-resolved fluorescence method provides a localized quantitative analysis for the phase transition processes of BLET ceramics. As this method is based on the fluorescence peak wavelength dependence on the crystal environment, it may potentially be used to characterize the phase transitions in other ferroelectric materials.

The behavior of room temperature phosphorescence quenching and fluorescence enhancing of gadolinium labeled sinoporphyrin sodium (Gd-DVDMS) in the aqueous solution were studied. Gd-DVDMS was characterized by various techniques including mass spectra, Fourier transform infrared spectra and transmission electron microscopy. The optical behavior was monitored through UV–vis absorption spectra and photoluminescence spectra. The result shows that the phosphorescence intensity gradually quenches, almost disappears after dissolved 120 min, meanwhile the fluorescence intensity enhances 5 times. The above behavior is attributed to the decreased population of Gd-DVDMS as first excited triplet state (T1). Based on the time-invariant of both absorption spectra and phosphorescence decay curves at 710 nm of Gd-DVDMS in different dissolution time, the reason for the decreased population of Gd-DVDMS in T1 state is that the intersystem crossing from first excited state (S1) to T1 is prevented. In addition, the fluorescent decay curves of Gd-DVDMS initially dissolved in the aqueous solution and dissolved for 120 min were also measured for comparison. The big change in fluorescent lifetime further proves the conclusion that intersystem crossing is prevented, meanwhile, the increase in fluorescence intensity is demonstrated. In this work, the possibility of decomposition of Gd-DVDMS is excluded because the phosphorescence decay curve in Gd-DVDMS aqueous solution is sensible to DVDMS.

Developing hard carbon with a high initial Coulombic efficiency (ICE) and very good cycling stability is of great importance for practical sodium-ion batteries (SIBs). Defects and oxygen-containing groups grown along either the carbon edges or the layers, however, are inevitable in hard carbon and can cause a tremendous density of irreversible Na+ sites, decreasing the efficiency and therefore causing failure of the battery. Thus, eliminating these unexpected defect structures is significant for enhancing the battery performance. Herein, we develop a strategy of applying a soft-carbon coating onto free-standing hard-carbon electrodes, which greatly hinders the formation of defects and oxygen-containing groups on hard carbon. The electrochemical results show that the soft-carbon-coated, free-standing hard-carbon electrodes can achieve an ultrahigh ICE of 94.1% and long cycling performance (99% capacity retention after 100 cycles at a current density of 20 mA g-1), demonstrating their great potential in practical sodium storage systems. The sodium storage mechanism was also investigated by operando Raman spectroscopy. Our sodium storage mechanism extends the "adsorption-intercalation-pore filling-deposition" model. We propose that the pore filling in the plateau area might be divided into two parts: (1) sodium could fill in the pores near the inner wall of the carbon layer; (2) when the sodium in the inner wall pores is close to saturation, the sodium could be further deposited onto the existing sodium.

The service performance of magnesium alloy wheel hub was simulated by studying the effect of surface defect size on the corrosion resistance of a calcium phosphate conversion coated AZ80 magnesium alloy. The surface defects were produced with different sizes using a Film Impactor. The corrosion behaviour was studied using electrochemical, hydrogen evolution and immersion tests. The microstructures were characterized using a scanning electron microscope and a laser confocal microscope. Phases and the corrosion products were analyzed using XRD and XPS. The size of the surface defects influenced the corrosion resistance of the coating and the corrosion initiation area. The coating provided no protection for an indentation larger than 2.7 mm. The corrosion mechanism of the coating was also clarified.

Semiconductor materials for energy storage are the core and foundation of modern information society and play important roles in photovoltaic system, integrated circuit, spacecraft technology, lighting applications, and other fields. Unfortunately, due to the long experiment period and high calculation cost, the high-precision band gap (the basic characteristic parameter) of semiconductor is difficult to obtain, which hinders the development of new semiconductor materials. Since the traditional Perdew–Burke–Ernzerhof (PBE) functional not only requires a long calculation time, but also significantly underestimates the band gap, we developed a deep learning model that can predict the more precise Heyd–Scuseria–Ernzerhof (HSE06) band gaps in milliseconds for 1,503 binary metallic oxides, nitrides, and sulfides, with a mean absolute error (MAE) of 0.35 eV, a mean squared error (MSE) of 0.21 eV, and a coefficient of determination (R2) of 0.98. Based on transfer learning, only 106 crystals), which is of great significance for the screening and discovery of new semiconductor energy storage materials.

Herein, the Cu target is prepared by combining different pieces, with a large variation in grain size, and installed in a UDP-650 closed-field unbalanced ion coating machine for sputtering experiments. The influence of grain size on surface morphology and sputtering performance of Cu targets is studied under the same process conditions. In the constant current mode, the sputtering voltage of target continues to decrease during the target lifetime, which is consistent with the increase of magnetic field intensity on the target surface due to the decrease of target thickness. During the first 7.5 h of sputtering erosion, the sputtering yield of Cu target slightly increases with sputtering time, followed by a gradual decrease. The results reveal that the grain size renders a significant effect on surface morphology of the Cu target after sputtering. The Cu target with small grain size renders high particle density in the edge area of sputter erosion groove, however, the particle-like morphology size is not influenced by the grain size. In the deepest region of sputtering erosion, the Cu target with two distinct grain sizes presents a flat morphology and the smaller grain size results in more flat morphology. At each stage of the life cycle of target material, the Cu target sputtering voltage initially decreases and, then, gradually becomes stable, while the cavity pressure initially increases and gradually becomes stable. The sputtering yield of the samples, with the grain size of 10–20 μm, is found to be greater than the samples with the grain size of 120–150 μm during each stage. Therefore, the Cu target with a small grain size should be selected to ensure the desired film deposition rate and stability of the sputtering process.

The hot tearing susceptibility of Mg-1Ca-xSr (x=0, 0.2, 0.4, 0.6, wt.%) alloys was investigated by CRC mold with a contraction force measurement system with a load cell and a temperature monitor. The results showed that the hot tearing susceptibility of Mg-1Ca-xSr alloys significantly improved with increasing of Sr content. Especially in Mg-1Ca-0.6Sr alloy, no visible tear was found on the casting sample. The force dropped and the final force value from the time-force-temperature curve derived from the hot tearing instruments could reflect the hot tearing susceptibility of different alloys. The mechanism of improved hot tearing resistance of Mg-1Ca-xSr alloys was clarified. In addition to susceptible temperature range and eutectic liquid fraction, it is found that the formation tendency of divorced eutectic also plays an important role on the hot tearing behavior of Mg-1Ca-xSr alloys.

Two unprecedented and stable metal-organic frameworks, {[Co2(H2O)2(L)(OH)]·2.5H2O·0.5DMF} n (1) and {[Ni2(H2O)2(L)(OH)]·1.75H2O} n (2), have been synthesized (H3L = 5-(5-carboxy-pyridin-3-yloxy)-isophthalic acid, DMF = N,N-dimethylformamide). Structural analysis shows that 1 and 2 are heteronuclear isomorphous, possessing a three-dimensional (3D) (4,8)-connected flu/fluorite topological framework formed through the interconnection of tetranuclear butterfly {M4(COO)6(OH)2} clusters and the ligands. Although the frameworks of these two compounds are similar, their magnetic properties are different. Compound 1 exhibits an antiferromagnetic interaction in the high-temperature region, while 2 shows a weak ferromagnetic interaction in the whole-temperature region. Furthermore, considering the presence of hydroxyl groups and water molecules in the frameworks, we tested their proton conductivity. The efficient proton transfer pathway in the framework endowed 1 and 2 with excellent proton conductivities of 9.07 × 10-5 and 1.29 × 10-4 S·cm-1 at 363 K and 98% relative humidity (RH), respectively.

As an important functional thin-film material in the field of electronic information, high-purity titanium (Ti) is widely used in different industries, such as integrated circuits, flat-panel displays and solar energy, indicating the importance of further research on Ti targets. Herein, a titanium target is placed in a UDP-650 closed-field nonequilibrium magnetron sputtering ion coating machine for deep etching to form racetrack grooves, and different positions of etching grooves are analyzed to understand the target etched behavior. The sputtering-induced etching of the Ti target, from shallow to deep regions, changes from the preferential sputtering of scratches and other defects in the edge area to the surface sputtering pits, with discontinuous distribution and uneven size, to grain boundary sputtering and, finally, to closely packed grain surface sputtering. The etching behavior of different regions exhibits different characteristics, mainly showing selective sputtering. The surface roughness of the sputtered area initially increases with the increase of sputtering depth and plasma density, followed by a slight decrease. Moreover, different degrees of incomplete recrystallization occur in different sputtering areas due to the uneven distribution of plasma on the target surface. The grain size increased from the transition area between sputtering and non-sputtering (112 μm) to the deepest sputtering area (139 μm). Moreover, the relationship between the cross-sectional grain size and sputter surface roughness renders a correlation coefficient of 0.802, indicating a strong influence of grain size on surface roughness. Therefore, it is of utmost importance to refine grains and increase the sputtering yield of the target as well as reduce the surface roughness of the target after etching to obtain a high-quality thin film.

Myocardial infarction is one of the common types of coronary heart disease in the clinic. Its morbidity, lethality and disability are high, and it has become a serious threat to human health. At present, it is shown that in the early stage of acute myocardial infarction, myocardial cells are mainly apoptotic, suggesting that effectively blocking myocardial apoptosis in the early stage of myocardial infarction is of great significance for reducing tissue necrosis in the infarcted area. Recent studies have shown that NG nano-protein complexes have a better therapeutic effect on acute myocardial infarction and can inhibit left ventricular remodeling in patients with acute myocardial infarction. However, there are few studies on the effect of NG nano-protein complexes on myocardial cell apoptosis after ischemia. This study used a rat model of acute myocardial infarction to analyze its effect on apoptotic proteins of myocardial cells in rats with acute myocardial infarction in order to provide a certain theoretical basis for its clinical application. In this study, 45 SD rats were randomly divided into a sham operation group, a myocardial infarction group, and a NG nano-protein complex group, with 15 in each group. The sham operation group only underwent thoracotomy, and received normal saline gavage postoperatively; the myocardial infarction group and the NG nano-protein complex group were ligated to the left anterior descending coronary artery of the rat to establish an acute myocardial infarction model, and were performed separately treatment with saline and NG nanoprotein complexes. Finally, we conclude that this nano-protein complex can significantly reduce the expression level of myocardial apoptosis-related proteins in rats with acute myocardial infarction, and is of great significance in inhibiting the apoptosis of acute myocardial infarction cells.

Laminates of carbon fibre reinforced polymer (CFRP) and titanium (Ti) alloy are used in aerospace applications and require holes for joining to other components, which can weaken them. In this study, to determine the influences of drilling and helical milling on the geometric accuracy of holes, holes were made in a CFRP/Ti-laminated structure by these two techniques, and variations in aperture and roundness at different positions were investigated. In two processes, apertures are larger in the middle and smaller at the ends, and most are larger than the apertures of standard holes (6 mm). With drilling, roundness is relatively high at hole entrances and exits. In helical milling, the maximum roundness occurs just underneath the hole entrance, while the minimum occurs at the exit. In the drilling of Ti alloy, the maximum aperture occurs at the entrance; however, with helical milling, the hole entrance aperture is smaller. The aperture at other positions is relatively small. During drilling, the maximum roundness occurs at hole entrances, while the minimum occurs just underneath and then increases with depth. Helical milling produces a relatively large roundness at hole entrances, with consistent variation in other positions. Generally, helical milling of a laminated structure produces better geometric accuracy in holes in the Ti alloy layer, better hole roundness in the CFRP layer, and smaller roundness in the transition zone. However, drilling achieves better aperture accuracy in CFRP and smaller aperture errors in the transition zone. These results will help to produce stronger CFRP/Ti-laminated structures.

An on-going challenge with Gasoline direct injection (GDI) engines is achieving rapid activation of the exhaust catalyst during cold starts, in order to reduce the Nitrogen Oxide (NOx) emissions. Injecting late in the compression stroke, in the efforts to form a stratified mixture, provides the fuel insufficient time to be entrained with the surrounding charge. This results in locally fuel rich diffusion combustion and the formation of high levels of particulate matter. Employing a split injection strategy can help tackle these issues. The current study examines the effects of a split injection strategy on the spray characteristics. Varying pulse width (PW) combinations, split ratios and dwell times are investigated using a Solenoid actuated high pressure injector. The injected quantity and the droplet characteristics of a target plume are investigated. The experiments were performed in a constant volume spray chamber. The droplet velocities and sizes were measured using Phase Doppler Particle Anemometry (PDA). Short and large PWs, in the range of 0.3–0.8 ms, were investigated. The results revealed that the highest injected quantity of fuel was measured with the shortest dwell time of 2 ms, owing to increased interactions between the injection events, which led to larger Sauter mean diameters (SMDs) measured. The SMDs for the shorter PW of 0.4 ms were generally larger than 0.8 ms PW. The droplets in this case were affected by the closely spaced opening and closing events of the Solenoid valve.

Gasoline spark ignition (SI) – Controlled auto-ignition (CAI) hybrid combustion had previously been shown to expanding the operational range of high-efficiency low-temperature combustion and reducing fuel consumption. However, the spark ignition became ineffective when the mixture became highly diluted and the large cyclic variation and even misfire would occur. To achieve high-efficiency combustion in extended engine operational range and overcome the limitation of SI-CAI hybrid combustion, Micro Flame Ignition (MFI) was proposed and researched as a mean to providing multiple auto-ignition sites to initiate the combustion process of the diluted mixture. In this research, both engine experiments and Computational Fluid Dynamics (CFD) simulations were carried out to study the MFI combustion and SI-CAI hybrid combustion in a single-cylinder optical engine. Compared to the SI-CAI hybrid combustion, the flame propagation in MFI hybrid combustion was initiated by a large number of reaction fronts produced by the DME auto-ignition at multiple sites. MFI was found to deliver substantially more heat and ignition energy to the premixed mixture than the single spark ignition, enabling much faster initial heat release. However, the flame front expansion speed of MFI hybrid combustion dropped significantly to a similar value to that of the SI-CAI case because of the slower flame speed of diluted gasoline mixture. The MFI combustion exhibited three phases of autoignition stage, flame propagation stage and fast heat release stage. It is characterized by a higher peak heat release rate and shorter duration of the main combustion than those of the SI-CAI combustion. Besides, the use of spark ignition in the MFI operation promoted the autoignition of DME, leading to a shorter combustion duration and faster combustion than the MFI combustion without spark ignition. As a result, the spark assisted MFI strategy could be used to control the combustion phasing and optimize the MFI combustion process.

Two cyanide-bridged V-shaped isostructural trinuclear complexes [{(Tp*)FeIII(CN)3}2MII(bztpen)]·Sol (M = Fe, Sol = CH3OH·3H2O, 1; M = Co, Sol = 2CH3OH·2H2O, 2; bztpen = N-benzyl-N,N′,N′-tris(2-methylpyridyl)ethylenediamine; Tp* = hydrotris(3,5-dimethylpyrazolyl)borate) were synthesized and characterized. The bztpen ligand serves as a tetradentate capping ligand around the inner metal ion, leaving one pyridyl group intact. Complex 1 exhibits a spin crossover (SCO) behavior between the {FeIIILSFeIIHSFeIIILS} and {FeIIILSFeIILSFeIIILS} spin isomers, while 2 shows both thermally- and photo-induced electron-transfer coupled spin transition (ETCST) property between the {FeIIILSCoIIHSFeIIILS} and {FeIIILSCoIIILSFeIILS} valence isomers. The total entropy changes for 1 and 2 between their corresponding two electronic states were found to be very close with the values of 87.46 and 84.49 J mol−1 K−1, respectively, indicating the comparable thermal energy barriers necessary for either an SCO or ETCST event for such a given system. Furthermore, both complexes undergo desolvation-induced irreversible and sharp magnetic change at high temperatures.

Here, we report an improved tandem catalytic mechanism for electroreduction of CO2 to C2H4. Cu(111) nanoparticles with an average size of 5.5 ± 0.9 nm were anchored on a conductive Cu-based metal–organic framework (Cu-THQ) by in situ electrochemical synthesis. Compared to Cu(111) nanoparticles, the C2H4 faradaic efficiency of the tandem catalyst Cu(111)@Cu-THQ was increased doubly.

Hydrogenation reactions are an important process in today's chemical industry. Typically, hydrogenation reactions involve the removal of an unsaturated bond in olefins or other polyenes via thermal catalysis using hydrogen. As hydrogenation reactions are often carried out at temperatures up to several hundred degrees, they require significant energy input which typically comes from burning fossil fuels. In order to conserve fossil fuels and reduce CO2 emissions, researchers are now developing photothermal catalysts for hydrogenation reactions, which harness concentrated sunlight to achieve the required reaction temperatures or introduce sunlight into thermal-driven reaction systems to reduce the reaction temperatures. Photothermal catalysts thus need to be able to efficiently absorb sunlight, whilst also being able to drive the desired hydrogenation reaction with high activity and selectivity. In this review, we summarize recent research aimed at the development of photothermal catalysts for CO2/CO hydrogenation and alkene/alkyne/aromatic hydrogenation. Particular emphasis is placed on uncovering the reaction mechanisms at the molecular level, which in turn guides the rational design of photothermal catalysts with better performance.

Herein, we report the synthesis of a new diiron azadithiolate compound {(μ-SCH2)2N(C6H4CH2CH2OH-4)}Fe2(CO)6 (1) and especially its covalent attachment onto benzoxy-functionalized single-walled carbon nanotubes (f-SWCNTs) to construct the first example of diiron azadithiolate clusters supported on carbon nanotubes (1-f-SWCNTs) for efficient electrocatalytic proton reduction to H2 in an aqueous medium. The structure and morphology of the as-prepared hybrid 1-f-SWCNTs have been well characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Notably, the 1-f-SWCNT hybrid absorbed on the cheap glassy carbon electrode exhibits a much more positive reduction potential (Epc) in pure water relative to an organic solvent (MeCN) and an outstanding turnover frequency (TOF) of 9444 s−1 for H2 production in the presence of 0.2 N aqueous H2SO4 as a proton source under electrochemical conditions.

It is still very challenging to obtain mechanochromic luminescence (MCL) systems that combine high-contrast photoluminescence colour change together with high quantum yields in any morphological state. In this paper, we have disclosed the reversible and high-contrast MCL properties from a triarylborane-based [2.2]paracyclophane, g-BPhNMe2-Cp, which contains 2-(dimesityboryl)phenyl and dimethylamino groups at pseudo-gem positions. With mechanical grinding, this compound exhibits a remarkable fluorescence change from blue fluorescence of the crystalline pristine powder to the green fluorescence of the amorphous ground powder with high fluorescence quantum yields of 0.58 and 0.73, respectively. In addition, the blue fluorescence can be reversibly restored upon fuming the ground powder with solvents. The structural analyses revealed that this compound is featured by a rigid and congested structure, which is helpful to suppress the intermolecular interactions, such as π–π stacking, aggregation, and excimer formation, and consequently enables the intense fluorescence in both morphological phases. The theoretical calculations suggested the remarkable two-colour fluorescence switching of g-BPhNMe2-Cp arising from the alternating excited state conformations formed in the crystalline and amorphous phases due to the different degrees of structural relaxation in the excited state.

With the rapid development of industrial production and aerospace, how to measure the plasma density has also developed rapidly. So a radio-frequency plasma transducer based on a three-layer dielec...

Temperature-dependent dual fluorescence and switchable circularly polarized luminescence (CPL) are two highly pursued but challenging properties for small organic molecules (SOMs). We herein disclose a triarylborane π-system based on a 2,2'-diamino-6,6'-diboryl-1,1'-binaphthyl scaffold that can serve as a versatile building block for achieving these two properties by simply choosing different amino groups. BNMe2 -BNaph with less bulky dimethylamino groups displays temperature-dependent dual fluorescence, and can thus be used as a highly sensitive ratiometric fluorescence thermometer. On the other hand, BNPh2 -BNaph with bulky diphenylamino groups exhibits intense fluorescence in both solution and in the solid state. A change of solvent from nonpolar cyclohexane to highly polar MeCN not only shifts the CPL position to much longer wavelength but also inverts the CPL sign. In addition, the complexation of BNPh2 -BNaph with fluoride greatly enhances the CPL intensity.

On-line heating rolling mill which could efficiently preheat sheet and apply tensile force on both ends of the sheet along rolling direction (RD) was used to investigate the effect of tension on mechanical behavior and shape quality of magnesium sheets. For revealing the influence mechanism, many analysis techniques including optical microscope, electron backscattered diffraction, macrotexture and transmission electron microscope were performed. The shape defect, edge wave, could be eliminated under higher tension along RD, which was attributed to more uniform distribution of microstructure and microstrain. Nevertheless, it is undesirable that the forward tensile force exceeds 3 kN in present work because the strength decreased for high recrystallization level when the tensile force is beyond this value. Furthermore, the main deformation mode was still slip during rolling process despite of accompanying twining, e.g., double twins, but more prismatic slip activated when tensile force exceeds 3 kN. The distribution of shear bands was affected by the applied tensile force that they appear as “V” shape along RD at a low forward or backward tensile force, while they appear as reticulate shape under applied tensile force of 5 kN.

A new method for mould filling calculation of lost foam casting (LFC) was developed based on the main hypothesis, which assumes that every point on the melt-pattern interface moves in the radial di...

The edge quality of AZ31 sheets prepared by online heating rolling (O-LHR) technique under different rolling temperatures has been investigated. The AZ31 sheets are rolled from 3 mm to around 1 mm via four passes under three different temperatures. Each pass reduction keeps a constant about 25%. For comparison, a series of sheets are also rolled by conventional rolling (CR) under the same condition. The macroscopic observation for sheets rolled by both processes and microstructure examination for the rolled sheets via O-LHR are performed to characterize the edge cracking behavior. The results reveal that the edge quality of sheets after O-LHR is better than that through CR and remarkably improves with the increase in temperature. No obvious edge crack appears in AZ31 sheet rolled by O-LHR at a rolling temperature of 250 °C. This can be attributed to the enhanced dynamic recrystallization and the activation of non-basal slip, which results in a homogeneous microstructure at the edge.

Co3O4 octahedrons enclosed by {111} facets were synthesized using Cl− ions as a crystal facet control agent. The Co3O4 octahedrons show higher responses than Co3O4 commercial particles to ethanol, methanol, acetone and triethylamine, and the responses are further enhanced by increasing the numbers of 3-coordinated Co atoms (Co3c) with one dangling bond at Co–Co3O4 (111) plane by eliminating surface Cl− ions and OH groups. Accordingly, we deem that the Co3c atom at (111) plane acts as an active center for sensing reaction and present an atomic and molecular level sensing mechanism. The Co3c atoms can produce free electrons, absorb O2 molecules and catalyze the gas-sensing reactions. The surface engineering may be used to bolster gas-sensing properties of other metallic oxides. The concept of Co3c atom as an active center will contribute to understand the true nature of the gas sensing and provide guidance on designing highly performance sensing materials.

The hollow microspheres assembled with ZnO nanoflakes exposing {001} facets have been successfully synthesized by annealing ZnS nanospheres at 550 °C for 2 h. Response of the hollow microspheres assembled from ZnO nanoflakes for ethanol, acetone, or triethylamine is significantly higher than hollow microspheres assembled from ZnO nanorod with dominant {100} facets. The exposed Zn-terminated (001) face is considered to be an active surface for gas sensing. Threefold coordinated Zn (Zn3c) atom with a dangling bond on the Zn-terminated (001) surface serves as a gas-sensing active atom, and thus a gas-sensing mechanism at atomic and molecular level is proposed. The concept of unsaturated Zn3c atoms as a gas-sensing active atoms will be useful for designing of high-performance sensing materials.

Aiming at the problem of negative segregation under a bloom surface, a coupling macrosegregation model considering electromagnetic field, flow, heat, and solute transport was established based on the volume average method to study the effect of in-mold electromagnetic stirring (M-EMS) on the negative segregation under the bloom surface. In the model, the influence of dendrite structure on the flow and solute transport was described by the change of permeability. The model was validated by the magnetic induction intensity of M-EMS and carbon segregation experiment. The results show that the solute C in the solidified shell in the turbulent zone of the bloom undergoes two negative segregations, whereby the first is caused by nozzle jet, and the second by the M-EMS. The severities of the negative segregation caused by M-EMS at different currents and frequencies are also different, and the larger the current is, or the smaller the frequency is, the more serious will be the negative segregation. With the M-EMS, the solute C distribution in the liquid phase of the bloom is more uniform, but the mass fraction of C in the liquid phase is higher than that without M-EMS.

A novel method enabling to produce a flat-top band-rejection filter is firstly proposed and experimentally demonstrated, which is achieved by using a phase-modulated helical long-period fiber grating (HLPG). Unlike most of the long-period fiber grating (LPG)-based and the HLPG-based band-rejection filters reported so far, the proposed band-rejection filter is inherently polarization-independent. Moreover, the proposed HLPG does not need a complex apodization in the grating’s profile, which considerably facilitates the fabrication processes and makes the designed HLPG particularly suitable for fabrication with using the CO2 laser-writing platform. As a typical example, a polarization-independent band-rejection filter with a bandwidth of ~10 nm@-20dB and a rejection depth of ~28 dB has been successfully achieved.

Char-pellet combustion is studied with the lattice Boltzmann method (LBM) including sodium release and the ash inhibition effect on oxygen diffusion in the porous char. The sodium release and the shrinking of the char pellet are simulated by accounting for the reactions occurring both in the solid and gas phases. The combustion of a single char pellet is considered first, and the results are compared against measurements. The simulation of the pellet mass, pellet temperature and sodium release agreed well with in-house optical measurements. The validated lattice Boltzmann approach is then extended to investigate the combustion of porous char and sodium release inside the porous medium. The pore-structure evolution and the flow path variation are simulated as combustion proceeds. The simulations reproduce the expected different behaviors between the combustion products (CO and CO2) and the released volatile, here the sodium vapor. The combustion products are mostly generated at the flame front and then transported by the flow and molecular diffusion inside the complex porous char structure. However, the volatile sodium vapor forms in the entire porous char and tends to accumulate in regions where the flow motion stays weak, as in internal flow microchannels, or blocked, as in closed pores. These results confirm the potential of the LBM formalism to tackle char-pellet combustion accounting for the topology of the porous medium. National Natural Science Foundation of China; China Postdoctoral Science Foundation; Royal Society and the Engineering and Physical Sciences Research Council (EPSRC) (UK)

In order to solve the problem of packer rubber failure at variable temperature and explore the effect of temperature on constitutive model of hydrogenated nitrile butadiene rubber (HNBR) for packer,this paper concludes that the Yeoh model is the most suitable for HNBR by comparing the experimental data at room temperature with the several common classical hyperelastic models. And it also concludes with a modified Yeoh model for different temperatures by modifing the material parameters as the temperature functions. And the stress-strain relationship of HNBR at different temperature is obtained,which can be used to prove the correctness of the model. Finally, the conclusion that the contact stress between packer rubber and casing increases with the increase of temperature is obtained through the case analysis of HNBR cylinder. The HNBR constitutive model obtained in this paper can provide theoretical basis for the engineering application of HNBR materials. It also extends the field that temperature affects on the HNBR constitutive model.

A series of isomorphic lanthanide coordination polymers with 2,6-dimethylpyridine-3,5-dicarboxylic acid (H2mpda), formulated as [Ln(Hmpda)3(H2mpda)] [Ln = Tb (1), Eu (2), Gd (3) and Ln = mixed lanthanide (4)], have been synthesized and structurally characterized. Single-crystal X-ray diffraction reveals that they are isomorphic and each displays a 1D chain-based structure, which can be expanded by hydrogen bond interactions into a 3D supramolecular architecture. In addition, they are thermally stable up to 350 °C and unusually chemically stable in a wide pH range of 2–13, which was confirmed by variable temperature XRD and pH dependent XRD. Meanwhile, the luminescence properties of compounds 1–4 are investigated. Of these, compound 1 acts as a luminescent probe for the sensing of temperature and pH, and compound 4 shows white light emission. Moreover, compounds 1, 2 and 4 were encapsulated in LED devices, with compound 4 exhibiting warm white light emission with excellent color rendering index (CRI) and correlated color temperature (CCT).

Recently, 2D electron gases (2DEGs) formed at oxide interfaces are drawing increasing attention as they cause a myriad of intriguing phenomena. As ideal platforms in supporting surface plasmon polaritons (SPPs) without metallic constituents, such 2DEGs are favorable in non-linear plasmonics for ultra-low total Joule dissipation. Convincingly, an increase in the interfacial electron density (IIED) formed at the interface of indium-tin-oxide and LiNbO3 composite slab is responsible for a number of interesting phenomena, which are hardly explained with the conventional photorefractive theoretical framework but can be satisfactorily elucidated via SPP excitation and resultant colossal non-linear effects. Since the polar-catastrophe-led IIED is universal to all combinations of highly polar ferroelectric oxides (FOs) and less polar transparent conducting oxides (TCOs), a systematic theoretical treatment of an FO/TCO system is pivotal to a variety of promising applications. In this study, the nanometer scale 2DEG at the FO/TCO interface is illustrated theoretically with the Thomas-Fermi screening picture, by taking into account the spontaneous polarization, along with related boundary conditions. The local plasma frequency of 2DEGs can be increased up to the UV regime for the composite slabs discussed, which are suitable for highly desirable visible applications. The SPP dispersion relationship was given for the 2DEG layer sandwiched between the FO slab and the unmodified TCO layer. To further take the non-uniform nature of IIED into account, dramatic dispersions of dielectric permittivity and index of refraction were simulated with a very broad range, hinting at different ways for meeting phase matching conditions and slowing the light for non-linear plasmonic applications, which are confirmed experimentally.

The surfaces of some IIB-VI semiconductors (ZnX, X = O, S, Se) are metallized by neighboring highly polar and atomically vertically aligned (VA) liquid crystal (LC) molecules. Owing to polar catastrophe, the charge carriers swarm in an extremely thin layer and the density can achieve 4.86 × 1028 m-3 close to the LC layer, which can be regarded as a 2-dimensional electron gas (2DEG). Using density functional theory (DFT), it was found that the dielectric functions of the modified layer become negative in the visible region. This indicates the semiconductor/LC platform is an ideal active plasmonic candidate, apart from the lossy metal constituents. Experimentally, after mediation with phase gratings written in the LC system, surface plasmon polaritons (SPPs) can be excited at the semiconductor surface and localized charges are gathered in an adjacent LC layer. With the help of the enhanced static electric field from the metallic surface, significantly more 2D diffraction orders in many rows and columns and a huge energy transfer between the laser beams and SPPs was observed, which is consistent with the metallization results and the bidirectional coupling between the SPPs and incident lights. The generalization of the II-VI semiconductors means the system has great promise for use in practical applications owing to the ultra-low loss. The novel insights regarding this combination with liquid crystals will be beneficial for real-time holographic displays and the study of tunable epsilon near zero points.

The effect of asymmetry deformation on microstructure and mechanical properties of AZ31 sheet was investigated in the present paper. Two AZ31 sheets were rolled together with an on-line heating rolling mill and separated from each other afterwards. For each sheet, the strain on both surface during rolling was asymmetry and this rolling method is called asymmetry rolling (AR) in present work. For comparison, symmetry rolling (SR) was also carried out on the same rolling mill that only one sheet was rolled in one pass. The sheets deformed by AR showed more homogeneous microstructure with higher recrystallization level and symmetry distributional basal texture. Moreover, SR sheets showed many narrow shear bands which distributed as “V” shape along rolling direction, while less shear bands with wider size are observed in AR sheet. The shear bands in AR sheet distributed as a line and across the entire thickness of the sheet, resulting in layered bimodal structure. Based on the unique microstructure and texture characteristics, AR sheet has lowest mechanical property anisotropy and a good balance of strength and elongation.

Dowelled joints loaded at an angle to the grain can fail in either a ductile or brittle way. In European design standard for timber structures, the load-carrying capacity of dowelled timber joints perpendicular to the grain is determined by the lower value of the ultimate yield load-carrying capacity of the joint with ductile failure mode based on the European Yield Model and the splitting capacity with brittle failure mode based on the fracture mechanics. However, a mixed failure mode can occur with a combination of the splitting of the timber and the plastic deformation of the fasteners. The available empirical formulae for the splitting capacity are mainly derived from the experimental results of the joints with rigid fasteners. This paper presents the tests on the dowelled joints with slotted-in steel plate under tensile loadings at different orientations with regard to the grain (90° and 45°) by yielding fasteners to validate the empirical formulae of the splitting capacity. In order to explicitly determine the failure mechanism of dowelled joints loaded perpendicular to the grain based on load-carrying capacity, the initial yield load-carrying capacity of the joint based on the European Yield Model (EYM) is proposed, from which the plastic deformation begins to occur in the embedded zone of the timber and steel fasteners. In practice design, through comparison of the initial yield capacities of the joints proposed in this study, the ultimate yield capacity based on the EYM according to EC5 and the splitting capacity according to DIN 1052, the failure modes can be accurately predicted and the ductility can be qualitatively estimated. The present experimental results together with those from literatures were used to validate the proposed design method.

Despite the extensive use of graphene-based materials in K-ion batteries, the effects of various edge morphologies of graphene on K atom adsorption and diffusion are unclear. In this study, the effects of K atom adsorption and diffusion on zigzag graphene nanoribbons (ZGNRs) with hydrogen (−H), ketone (=O), hydroxyl (−OH), and carboxyl (−COOH) terminal groups were investigated by density functional theory calculations. ZGNRs terminating with −H, =O and −COOH promote K atom adsorption, whereas those terminating with −OH suppress it. The −H, =O, −OH and −COOH terminations have a negligible effect on K atom diffusion in the inner region of ZGNRs. In the edge region, the diffusion barriers are nearly unchanged for −H and −OH terminations; however, they are increased for =O and −COOH terminations in the edge region compared to those in the inner region. All the terminal groups hinder K atom diffusion from the edge region toward the inner region. Our results suggest that −H termination enhances K atom adsorption and has a negligible effect on the diffusion barrier of K atom in the edge region. Therefore, the ZGNR with −H termination could be a promising candidate for K-ion batteries.

Remarkable spots and lines were clearly observed at the two interfaces of indium-tin-oxide coated Z-cut Fe-doped lithium noibate plates under illumination by milliwatt continuous-wave laser light; this occurred because of the visible surface plasmons (SPs) supported by the promising non-metal plasmonic system. The intriguing observations are here explained via the SP-strengthened nonlinear effect, through consideration of the electrostatic field (which is comparable to the atomic field) and its large gradient; this hints at a promising, highly sensitive plasmonic system. The gigantic nonlinear effect discussed in this paper should be ubiquitously existed in many oxide ferroelectric/semiconductor combinations and is promising for visible plasmonic applications.

Circularly polarized luminescence (CPL) has shown promising application potentials in 3D display, optical data storage, smart sensors/probers, CPL lasers, and light source for asymmetric photosynthesis. In the last decade, the CPL-active small organic molecules (CPL-SOMs) have attracted rapidly increasing research interest owing to the great advantages of SOMs, such as high luminescence efficiency, facile modification of chemical structure, fine emission wavelength tuning, precise relationships between structure and properties, and as well as easy fabrication. Promoted by the unique effects of boryl group, such as strong electron-accepting ability, great steric effect, and Lewis acidity to bind with Lewis bases, we herein summarized our recent research results about the creation of CPL-SOMs by modification of chiral scaffolds, such as [2.2]paracyclophane, [5]/[7]helicene, and binaphthyl, with boryl group. The preliminary results have well demonstrated that the chiral triarylborane-based SOMs exhibit promising CPL properties, such as intense CPL in combination of high luminescence dissymmetry factor (|glum |) with high fluorescence efficiency, solvent-induced sign inversion, facile emission wavelength tuning, high fluorescence efficiency in the solid, and substituent-induced sign inversion.

The data of this paper can be accessed from the Brunel University London data archive, figshare at https://doi.org/10.17633/rd.brunel.14797920. Paper 134 Section: Fuel sprays & Combustion Copyright © 2021 The Authors. The outward-opening piezoelectric injectors are capable to achieve precise and flexible controls of the fuel injection rate and duration with rapid opening and closing for split or multiple injections, which can minimise wall wetting and deposit formation in Gasoline Direct Injection (GDI) engines. However, experimental studies have shown that narrowly spaced split injections with short dwell time can increase cycle-to-cycle variation and emissions. In this study, large eddy simulations (LES) of an outward-opening piezoelectric gasoline injector were performed to understand the interactions between split injections and their impact on the flow fields, fuel/air mixing and transportation. The simulations were performed in a constant volume vessel and validated with experimental data. The results at both 1 bar and 10 bar backpressures showed that the droplets, fuel vapor and flow fields distributions were significantly affected by split injections when short dwells (0.6 ms and 1 ms) were applied. In particular, the fuel vapor distribution at recirculation zones of the spray where the spark plug is normally positioned was significantly changed after the second injection, compared to that of single injection, implying potential impact on the ignition stability. UKRI Future Leaders Fellowship (MR/T042915/1).

Materials innovation calls for an integrated framework combining physics-based modelling and data-driven informatics. A dislocation-based constitutive model accounting for both transformation-induced plasticity (TRIP) and twinning-induced plasticity (TWIP) was built to interpret the mechanical characteristics of metastable titanium alloys. Particular attention was placed on quantitatively understanding the composition-sensitive phase stability and its influence on the underlying deformation mechanism. For this purpose, a pseudoelastic force balance incorporating thermodynamics and micromechanics was applied to calculate the energy landscapes of β → α″ martensitic transformation, {332}〈113〉 twinning and dislocation slip. Extensive material data were probed, computed and fed to the model. Our results revealed that TRIP and TWIP may operate simultaneously because of the presence of a noticeably overlapped energy domain, and confirmed {332}〈113〉 twinning is an energetically favourable deformation mechanism. The model validation further unveiled that the activation of β → α″ transition remarkably enhances the strain-hardening and plasticity, even though the dynamically formed α″ volume fraction is much less than that of deformation twinning. Our work suggests that the synchronised physical metallurgy and data-driven strategy allows to identify the compositional scenarios for developing high-performance engineering alloys.