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Tuning white-light emission via free radicals is still a challenge in molecular-based functional materials. Herein, a new photoactive Zn2+ oxalate-based chain containing a polypyridine ligand was designed and synthesized with remarkably bifunctional photochromism and photo-actuated greenish white-light emission after UV, sunlight or Xe lamp light irradiation at room temperature. The photo-actuated coloration process was induced by the photogeneration of stable radicals originated from intermolecular electron transfers from oxalate components to the protonated polypyridine units, as demonstrated by UV-vis, IR, electron spin resonance and X-ray photoelectron spectra and magnetic measurements. Importantly, the on/off greenish white light emission (WLE) could be reversibly switched by generation and elimination of radicals via light irradiation and heat treatment, providing a feasible strategy for designing photoswitchable light emission diodes materials.

The growing demand for brilliant smile and tooth whitening has led to the increasing significance of tooth whitening methods. However, the development of tooth whitening materials with high efficiency and safety has been considered to be an urgent challenge. Here, we report a novel tooth whitening strategy, which overcomes the limitation of conventional methods, shows excellent tooth whitening efficiency and safety, and even exhibits outstanding antibacterial activity. Inspired by stomata and chloroplasts in green leaves, we have developed an integrated two-phase free radical hydrogel (TP-GEL), which integrates solid-phase and liquid-phase free radical functional components fabricated by cold plasma technology. TP-GEL demonstrated safe and ultrafast tooth-whitening effect with or without visible light, which can be more significant than that of 30% H2O2, the commonly whitening material in dental clinical practice. More importantly, we also avoid the damage to enamel, such as microhardness, roughness, surface morphology. Benefiting from free radicals, much higher antibacterial properties than commercial products (Chlorhexidine) was obtained. This research provides fundamental design criteria for the development of dual functional oral health care materials with advanced tooth whitening and antibacterial activity.

Gelatin methacrylate (GelMA) hydrogels are a promising material for use in a variety of tissue engineering applications. Herein, we focused on identifying the optimal irradiation time necessary to photopolymerize GelMA hydrogels with visible blue light in a manner that did not adversely impact the biophysical properties of these cell-containing gels. We assessed the toxic effects of different irradiation times (3, 5, 10, 20 and 40 seconds) on BMMSCs encapsulated in a GelMA hydrogel using lithium phenyl-2,4,6 trimethylbenzoylphosphinate (LAP) as a photoinitiator. Both CCK-8 assays and Live-Dead staining were used to measure BMMSCs viability. We observed increasing compression strength as a function of increased irradiation time, although this corresponded to a reduction in swelling ratio and pore sizes. We ultimately found that when using LAP as a photoinitiator, the optimal irradiation time was 5–10 seconds, which was suitable for bone tissue engineering application. Ultimately we determined that a 5 second irradiation time was optimal for studies of encapsulated stem cells.

This study investigates complex acoustical intensity using a polyvinylidene fluoride (PVDF) bimorph. Analytical models of the open-circuit voltage outputs of an infinite-strip-shaped PVDF bimorph cantilever in an underwater sound field are developed. Results show that the sound pressure generates the sum of the outputs, while the particle velocity normal to the PVDF surface generates the difference. The sensitivities of the pressure- and velocity-generated voltage responses with respect to an incident plane sound field demonstrate uniform directivity in a low-frequency range, which is suitable for acoustical intensity determination. The higher velocity sensitivity confirms the advantage of using a PVDF bimorph as a velocity sensor, owing to its light weight and flexibility. An algorithm for determining the complex acoustical intensity normal to the surface is proposed by utilizing those voltage responses and the probe gain calibrated with a given angle of incident sound. This algorithm allows accurate determination of sound intensity of a plane wave field, where the reactive part of intensity is absent. However, a small error may exist when the reactive intensity is large and active intensity is small. This small discrepancy arises from the inherent variation in the phase directivity of the gains, which decrease with frequency.

The sensitivity of an infinite-strip-shaped polyvinylidene fluoride (PVDF) film in an underwater plane sound field is analyzed in this paper. The high-frequency sensitivity is characterized by the resonances of the symmetrical in-plane stress modes with traction-free boundary conditions at the ends of the film and by the anti-resonances due to the superposition of the stress components. The low-frequency sensitivity exhibits a simple hydrostatic response. The directional property of the in-plane stress component, generated by the incident sound across the thickness, has two contributions. The first is from the aperture and dipolar functions of the incident sound pressure over the PVDF surfaces and at the two ends of the film. The second is from an amplitude modulation by an angle-dependent gain. The directional property of the in-plane stress component by the sound pressure at the two ends of the film is only controlled by the dipolar function, and that of the stress component in the thickness direction is only determined by the aperture function. The illustration of the frequency and directional features of the PVDF film may advance understanding of the mechanisms involved in generating the voltage output of PVDF by an incident sound field.

The development of new hybrid photochromic materials (HPMs) systems received huge interest of chemists because of their potentialities in many domains and feasibilities of obtaining other photomodu...

Heterogeneous nanostructured metals are emerging strategies for achieving both high strength and ductility, which are particularly attractive for high entropy alloys (HEAs) to combine the synergistic enhancements from multielement composition, grain boundaries, and heterogeneity effects. However, the construction of heterogeneous nanostructured HEAs remains elusive and can involve delicate processes that are not practically scalable. Herein we report using composition design (i.e., enthalpy engineering) to create hierarchical, nanostructured HEAs as demonstrated by adding Ni into FeCrCoAlTi0.5 HEA. The strong enthalpic interaction between (Ni,Co) and (Al,Ti) pairs in FeCrCoAlTi0.5Nix (x = 0.5–1.5) induced phase partitions into B2 (ordered phase, hard) matrix and A2 (disordered phase, soft) precipitates, resulting in a hierarchical structure of B2 grains and sub-grains of near-coherent A2 nanodomains (∼ 12.5 nm) divided by A2 interdendritic regions. As a result, the FeCrCoAlTi0.5Ni1.5 HEA with this unique hierarchical nanostructure exhibits the best combination of strength and plasticity, i.e., a 2-fold increase in compressive strength (2.60 GPa) and significant enhancement of plastic strain (15.8%) as compared with the original FeCrCoAlTi0.5 HEA. Enthalpy analysis and simulation study reveal the phase partition process during cooling induced by an enthalpy-driven order-disorder transition while the order parameters illustrate the strong ordering in (Ni,Co)(Al,Ti)-rich B2 phase and high entropy mixing in less interactive FeCrCo-rich A2 phase. Our work therefore provides a strategy for hierarchical nanostructured HEA formation by composition design considering enthalpy and entropy interplay.

Based on the assumption of gas-liquid stratified flow pattern in inclined gas wells, considering the influence of wettability and surface tension on the circumferential distribution of liquid film along the wellbore wall, the influence of the change of the gas-liquid interface configuration on the potential energy, kinetic energy and surface free energy of the two-phase system per unit length of the tube is investigated, and a new model for calculating the gas-liquid distribution at critical conditions is developed by using the principle of minimum energy. Considering the influence of the inclination angle, the calculation model of interfacial friction factor is established, and finally closed the governing equations. The interface shape is more vulnerable to wettability and surface tension at a low liquid holdup, resulting in a curved interface configuration. The interface is more curved when the smaller is the pipe diameter, or the smaller the liquid holdup, or the smaller the deviation angle, or the greater gas velocity, or the greater the gas density. The critical liquid-carrying velocity increases nonlinearly and then decreases with the increase of inclination angle. The inclination corresponding to the maximum critical liquid-carrying velocity increases with the increase of the diameter of the wellbore, and it is also affected by the fluid properties of the gas phase and liquid phase. The mean relative errors for critical liquid-carrying velocity and critical pressure gradient are 1.19% and 3.02%, respectively, and the misclassification rate is 2.38% in the field trial, implying the new model can provide a valid judgement on the liquid loading in inclined gas wells.

Plasma-assisted ignition and combustion are promising approaches for controlling ignition enhancement and flame stabilization. The global loosely coupled plasma-assisted combustion kinetic model has been established by combining the ZDPlasKin and ChemKin codes, which is employed to numerically investigate the effects of the inert gas-diluted methane-air nanosecond repetitively pulsed (NRP) plasma on the ignition process. The results indicate that addition of the inert gas is conducive to increasing the chemical reactive species densities in the methane-air NRP discharge plasma. The addition of inert gases affects the generation pathways of plasma species and their corresponding contribution rates. Compared with the methane-air plasma, the dilution of inert gases shows obvious effects on reducing ignition delays, and the dilution of He and Ar decreases the ignition delays by 58.0 and 84.0%, respectively. CH3 + O2 = CH3O + O and H + O2 = O + OH are the dominant conducive reactions in the methane-air ignition chemistry. Moreover, the dilution of inert gases has considerable influences on the normalization sensitivity coefficients, especially for the reaction of H + O2 = O + OH.

Electron leakage through the solid-state electrolyte interphase (SEI) in Li-ion batteries causes the reduction of the electrolyte and the consumption of Li-ions, decreasing the battery capacity and...

Crystalline complexes that exhibited light switchable proton conductivity are of great interest but still a challenge in material science. Herein, a terbium phosphonate chain complex was synthesized through assembly of electron-rich phosphonate units, electron-deficient polypyridine components and paramagnetic Tb3+ ions. Via light irradiation and heat treatment, the photogenerated radicals could simultaneously and reversibly tune the photochromic, luminescent and magnetic properties. Originated from the abundant hydrogen bonding networks formed between PO3 groups and lattice water molecules, proton conductive behaviour was explored with high proton conductivity of (1.74±0.19)×10−3 S cm−1 at 80 °C and 100% relative humidity. Importantly, accompanied with the colorless sample changed to blue, the proton conductivity increased about 20% after room temperature light illumination, implying that light irradiation could act as an external stimulus to enhance the conductive properties of original material. This work innovatively realized the light responsive conductive property in the electron transfer photochromic materials, providing a novel strategy for the construction of smart materials.

Using a pyridine-derived molecule 1,3,5-tris(4-pyridyl)benzene (TPB) and a polycarboxylate linker 1,3-benzenedicarboxylic acid (H2BDC), a Co(II)-based coordination polymer {[Co(TPB)(BDC)]·0.5H2O} (...

In this study, the effect of axial heat conduction on thermal performance in a zigzag channel printed circuit heat exchanger (PCHE) with supercritical liquefied natural gas as the working fluid is studied by a numerical method under different conditions. The influence factors include Reynolds number, operating pressure, inlet temperatures of the cold side, and wall thermal conductivity. The results indicate that the axial heat conduction can greatly affect the thermal performance of the PCHE at low Reynolds numbers but decrease it at high Reynolds numbers for different working conditions. At the same average Reynolds number, the thermal performance of the PCHE decreases as the pressure increases, and the inlet temperature of 195 K provides the best thermal performance while the inlet temperature of 220 K is the worst among the three different inlet temperatures of the cold side. Furthermore, the reduction of wall thermal conductivity can improve the thermal performance of the PCHE due to the influence of axial heat conduction in the separation wall.

Low-temperature synthesis of large-area graphene films by chemical vapor deposition (CVD) method has attracted extensive research interests owing to their extraordinary potential applications. Current reports on the low-temperature graphene growth usually involve catalytic metal substrates, which exceedingly impedes the direct use of graphene in nanoelectronic fabrications. In this project, we design a space-confined growth chamber utilizing two SiO2/Si chips. The bottom chip loading pre-transferred graphene flakes accommodates the growth of second monolayer graphene, with a tellurium (Te) vapor assisted growth process. Polymethylmethacrylate (PMMA) residues introduced from the transferred graphene substrate is employed as the solid carbon source. Further, the numerical simulation results prove that the high concentration of active carbons in the confined space plays a vital role in this growth process. Density functional theory (DFT) calculations reveal that, Te atoms prefer to bond with the edge carbons of small graphene flakes and serve as an effective catalyst, which helps to grow small graphene flakes by reducing their energy of formation. The successful growth can provide the high-quality monolayer graphene grains at the low temperature (∼350 °C). This facile strategy promises the mass production of graphene at mild conditions and low costs, which contributes to the green chemistry in future.

In this work, highly hydrophobic carbon sponges with large specific surface area were successfully prepared (denoted as HHCS-1, HHCS-2 and HHCS-3). By simply increasing temperature and decreasing heating rate, the carbon sponge showed unique sphere structures at the points of each connection. Moreover, the unique sphere structure changes from no obvious fold to obvious fold. HHCS-3 with the largest surface area of 2926.2 m2 g−1 exhibited superior adsorption performance for methanol, acetone and toluene, and the largest saturated adsorption capacity reached as high as 172, 365 and 429 mg g−1. The ultralow water vapor absorption rate indicates that HHCSs have excellent hydrophobicity and water vapor uptakes are only 7.62%, 6.71% and 6.25% at the relative humidity of 50%. When water vapor was introduced into toluene gas (RH = 50%), the toluene-saturated adsorption capacities are only reduced by 7.2−8.6% compared with under dry conditions. The adsorption capacity of toluene on the HHCSs is higher than that of methanol and acetone. Kinetic adsorption models show that the adsorption of methanol, acetone and toluene onto HHCSs mainly depends on surface adsorption.

We report the observation of Peierls-type metal-insulator transition in carbon nanostructures formed by chemical vapor deposition inside the pore network of the ZSM-5 zeolite. The Raman spectrum of this nanocarbon@ZSM-5 indicates a clear signature of the radial breathing mode (RBM) for (3,0) carbon nanotubes that can constitute the carbon network segments. Electrical transport measurements on multiple few-micron-sized nanocarbon@ZSM-5 crystals showed metallic temperature of resistance dependence down to 30 K, at which point the resistance exhibited a sharp upturn that is accompanied by the opening of a quasigap at the Fermi level as indicated by the differential resistance measurements. Further Hall measurements have yielded both the sign of the charge carrier and its density. The latter demonstrated excellent consistency with the quasigap data. We employed first-principles calculations to verify that there can indeed be softening of the phonon modes in the (3,0) carbon nanotubes., 17 pages, 6 figures in main text, 2 figures in Supplemental Materials. To be published

By employing a triazole–pyridine-containing ligand, two novel coordination polymers with Ag(I) clusters exhibiting different architectures have been successfully constructed. Structural analysis indicates that diverse coordination modes of the N-donor linker are responsible for the network difference for these two compounds, affording an isolated cluster for 1 and a 2D framework for 2, respectively. Compound 1 features a butterfly-shaped [Ag8(bptp)4(H2O)2] cluster wherein strong argentophilic interactions could be observed. The linkage of Ag(I) with N and I centers gives rise to a tetranuclear building unit [Ag4(bptp)3I] in 2, which is further extended to a 2D network with the assistance of the N-donor linkers. The syntheses and crystal structures have been investigated. Solid-state photoluminescence emissions as well as luminescence lifetimes of 1 and 2 have also been studied. Moreover, temperature-dependent luminescence tests show that an excellent linear relationship between temperature and emission intensity in the ranges of 77–298 K and 77–200 K could be observed for compounds 1 and 2, respectively. The wide temperature sensing range especially for 1 implies that they could act as promising ratiometric fluorescence molecular thermometers.

Metal–organic complexes (MOCs) derived porous carbon have attracted considerable attention due to easy functionalization with metal/metal oxides or other heteroatoms and hierarchical porosity. Herein, four g-C3N4/TiO2/CNOT photocatalyst structures were prepared via a reasonable design and control of the amount of MOC crystal materials. g-C3N4/TiO2/CNOT photocatalysts have a 3D porous structure, high surface area and heterojunction interface between g-C3N4 and TiO2, which together enhance the adsorption and photocatalytic performance. The 3D porous structure of g-C3N4/TiO2/CNOT supplied multidimensional adsorption-enrichment sites, and the heterojunction promoted the separation of the photogenerated electrons and holes. The g-C3N4/TiO2/CNOT-15 photocatalyst with the highest surface area reached up to 1644.1 m2 g−1. Heterojunctions promoted the separation and migration of the photogenerated electrons and holes. Benefiting from the above-mentioned excellent characteristics, g-C3N4/TiO2/CNOT exhibits efficient synergistic adsorption–photocatalysis performance for the removal of chlortetracycline hydrochloride (CTC-HCl). Apparently, g-C3N4/TiO2/CNOT-15 shows the highest CTC-HCl photocatalytic efficiency up to 97.8% after 60 min in the static system. In the dynamic system, the maximum CTC-HCl removal rate reached 35.5% and equilibrium removal rate was 19.9%. Free radical trapping experiments demonstrated that ˙O2− radical, ˙OH radical and holes serving as active species work together to promote photocatalytic reactions. This study provides a clear direction for the preparation of a 3D porous heterojunction for the efficient removal of antibiotics via synergy adsorption and photocatalysis.

Hybrid photochromic materias (HPMs), especially crystalline HPMs (CHPMs), have been widely investigated due to their feasibility in maintaining the advantages of each constituent and genearating captivating photomodulated functionality. Metal-organic complexes (MOCs), as promising candidates for fabricating CHPMs, have attracted the interest of researchers. The molecular predesign of ligands plays a crucial role in yielding MOC-based CHPMs with tunable photochromic functionality. Hitherto, a great majority of CHPMs are driven by photosensitive ligands. However, the complicated synthesis and high cost of photosensitive ligands obviously prevent the macro-synthesis and future application of these CHPMs. Thus, it is indispensable to explore novel branches of CHPMs. Herein, we report a series of photochromic solid materials bearing modulated photochromic properties by hybridizing metal chlorides with a nonphotosensitive coplanar dipyridine unit 1,10-phenanthroline (phen) and its derivative 5-chloro-1,10-phenanthroline (5-Cl-phen). The resulting hybrids, [ZnCl2(phen)] (1), [CdCl2(phen)] (2), [PbCl2(phen)] (3), [ZnCl(H2O)(5-Cl-phen)2]Cl·2H2O (4), [Cd2Cl4(5-Cl-phen)2] (5) and [Pb2Cl4(5-Cl-phen)2] (6), exhibit distinct structures from the isolated molecular complexes (1 and 4) to the hybrid chain (2, 3, 5 and 6) because of the distinct coordination mode of central metal ions and chloride ions. After photo-irradiation with a Xe-lamp, all complexes, as expected, exhibited apparent color change because of the photoinduced electron transfer (ET) between coordinated chloride ions (Cl-) as electron donors (EDs) and the coordinated coplanar phen and 5-Cl-phen species as electron acceptors (EAs). More importantly, the photochromic performance of the title complexes could be modulated by phen and 5-Cl-phen. This study provides a general and facile way for modulating the structure and photochromic performance of hybrid metal chlorides with phen or phen-based derivatives under the synergy of crystalline engineering strategy and ET mechanism.

Currently, about 90% of methane (CH4) is used in various combustion processes, releasing carbon dioxide into the atmosphere. In order to optimize the use of fossil-fuel energy and reduce greenhouse gas emissions, finding effective ways to convert CH4 into fuels and chemicals has become a research focus in academic circles and industry. Activating the strong C(sp3)–H bond (434 kJ mol−1) in CH4 under mild conditions is one of the most rigorous challenges. The use of a plasma for dissociating CH4 to CH3 free radicals has advantages over conventional pyrolysis approaches. This work aims to increase the CH3 production rate at low temperature by use of a nanosecond repetitively pulsed dielectric barrier discharge plasma with optimization of several parameters, including pulse rise time, pulse width and pulse repetition frequency. The maximum CH4 conversion reaches 31.9% when the pulse repetition frequency is increased to 9 kHz, while the dominant C2 hydrocarbon is always C2H6 (from CH3 coupling reaction). A chemical kinetic model confirms that H and CH3 are the critical radicals produced from electron-impact CH4 dissociation, with their peak densities of the order of 1015 cm−3 and 1014 cm−3, respectively. The results indicate that the improved plasma technology can continuously produce abundant H and CH3 radicals, which would enhance the surface reactions on the catalyst in the plasma-catalytic CH4 conversion process.

The combination of a conjugated coplanar dipyridine moiety 1,10-phenanthroline (1,10-phen) with a metal carboxylate system produces two isostructural supramolecular chains [M(HBTA)(1,10-phen)2] (M = Zn for 1, M = Cd for 2) (H3BTA = benzene-1,2,3-tricarboxylic acid). Both 1 and 2 feature monomeric units as molecular building blocks (MBBs), which further connect with each other to form a supramolecular chain via forming hydrogen bonds with adjacent units. The coordinate linkage of 1,10-phen as π-electron acceptors (π-EAs) and tricarboxylate as electron donors (EDs) results in the electron transfer (ET)-induced photochromic functionality of 1 and 2 in response to Xe-lamp irradiation under ambient conditions. Distinct from the plenty of previous photochromic compounds derived from photosensitive moieties such as pyridinium-derivatives and photodeformable molecules, the photochromism in 1 and 2 is driven by the photoinduced ET between tricarboxylate and non-photochromic 1,10-phen units. Because of the coplanar characteristics of 1,10-phen, the photoactivated samples feature good stability under ambient conditions. More importantly, the resulting photochromism of isostructural 1 and 2 could be modulated by the category of metal ions, which is totally different from the previous works with focus on the design of organic ligands. Considering the great varieties of carboxylate ligands, this work offers a general method for the construction of photochromic complexes via integrating coplanar 1,10-phen units with metal-carboxylate systems under the guidance of the ET mechanism and MBB assembly strategy and modulating the photochromism of the resultant isostructural products via tuning the category of metal ions.

Plasma-assisted combustion is a promising approach to achieve fast ignition and highly efficient combustion. In this work, methane–air nanosecond pulsed dielectric barrier discharge plasma-assisted combustion is numerically investigated by combining a homemade plasma model with the combustion model of software CHEMKIN-PRO. Effects of varying applied voltage amplitudes on the characteristic parameters of the plasma-assisted planar shear flow combustion as well as the reaction pathway maps of not only the nanosecond pulsed dielectric barrier discharge plasma but also the combustions without and with plasma assistance are systematically illustrated and analyzed. The simulation results indicate that under the combined action of increasing electric field intensity and increasing charged particle densities, the peak value of the discharge current density increases, and the peak time of the discharge current density is brought forward with the increase of the applied voltage amplitude. The temperature reaches its peak value earlier in the methane–air combustion with plasma assistance than without plasma assistance. The maximum temperature reduces to around 1900 K when the applied voltage amplitude is higher than 11 kV. There are emerging pathways to generate hydrocarbons C2H4 and C2H2 in the plasma-assisted combustion, the reactions of CH4 on CH and C2H on H2, respectively. The reactions involving active species such as H play a significant role in the plasma-assisted combustion, which causes an obvious decrease in the densities of these active species with plasma assistance.

Metal–organic frameworks (MOFs), as an emerging hybrid material, have been well explored in numerous areas such as adsorption, separation, catalysis, magnetism, photoluminescence, etc. Recently, th...

Wet gas can form liquid loading at the lower line pipe sections, so the transportation efficiency will be impacted and the line pipes will be corroded and even blocked. Therefore, to accurately predict the critical liquid-carrying velocity of gas is of great significance to preventing the liquid loading in wet gas line pipes. In view of the gas–liquid two-phase stratified flow in micro-tilting line pipes with low liquid content, this paper newly established a critical liquid-carrying velocity prediction model considering droplet entrainment according to the momentum balance equation of a gas–liquid two-phase flow and the closure relationship of a new gas–liquid interface shape. Then, based on the experimental data, the new model, FLAT model, ARS model, double-circle model and MARS model were verified and their prediction results were compared. Finally, the new model was applied to analyze the effects of pipe dip, operational pressure, liquid density and gas component on the critical liquid-carrying velocity and critical liquid content of natural gas–water and natural gas–60% glycerine with water stratified flow in a micro-tilting line pipe. And the following research results were obtained. First, with the increase of pipe dip and liquid density, the critical liquid-carrying velocity increases continuously and the critical liquid content decreases gradually. Second, with the increase of operational pressure and heavy component content, the critical liquid-carrying velocity decreases continuously and the critical liquid content increases gradually. In conclusion, the new model is higher in prediction accuracy and its prediction result is better accordant with the experimental value, so it can be used to predict the critical liquid-carrying velocity in wet gas line pipes.

We present a new solid-state material phase which is a disordered solid solution but offers many ordered line-compound features. The emergent physical phenomena are rooted in the perfect short-range order which conserves the local octet rule. We model the dual-sublattice-mixed semiconductor alloy $${\mathrm{(ZnSnN}}_{\mathrm{2}}{\mathrm{)}}_{1 - x}{\mathrm{(ZnO)}}_{2x}$$ (ZnSnN 2 ) 1 − x (ZnO) 2 x using first-principles calculations, Monte-Carlo simulations with a model Hamiltonian, and an extension of the regular solution model by incorporating short-range order. We demonstrate that this unique solid solution, occurring at a “magic” composition, can provide an electronically pristine character without disorder-induced charge localization and, therefore, a superior carrier transport similar to ordered phases. Interestingly, this phase shows singularities that are absent in the conventional solid-solution models, such as the regular solution and band-gap bowing model. Thermodynamically, this alloy phase has a sharply reduced enthalpy at its composition (like a line compound), but it still requires the entropy from long-range disorder to be stabilized at experimentally accessible temperatures.

In this study, the thermal and hydraulic performances of six different printed circuit heat exchanger (PCHE) configurations with supercritical liquefied natural gas as the working fluid are studied...

This work outlines an experimental investigation of grain-size-dependent structure evolution under tension in nickel with a grain size gradient. Two opposite and competing processes, grain refinement and coarsening, were examined within one specimen, due to the widely ranging grain size in gradient-structured (GS) Ni. A tension-induced minimum grain size of approximately 280 nm was determined in GS Ni, which is comparable to those obtained by severe plastic deformation processes. The minimum grain size was phenomenologically explained using a dislocation model. Below the minimum grain size, the Ni's grain coarsening ability peaked at approximately 50 nm and progressively decreased with decreasing grain size, showing an inverse grain-size-dependent coarsening tendency. Moreover, this inverse grain coarsening behavior was related to a transition in the deformation mechanism, through which the deformation process was accommodated more by partial dislocation than by full dislocation below a critical grain size. This was confirmed by observation of the microstructure and low temperature tensile testing results. This work demonstrates a high-throughput strategy for exploring the minimum grain size and grain-size-dependent coarsening in metals.

A numerical model is established to simulate the thermal performance of supercritical LNG (SLNG) at different arrangement orientations in submerged combustion vaporizer (SCV). The SST k-ω turbulent...

The realization of high strength and toughness for self-healing polymeric materials is vital for practical applications in many fields. However, the development of tough self-healing materials rema...

Guided by diverse solvated metal cations, three novel iodoargentates with various architectures ranging from a one-dimensional chain to a two-dimensional layered-network have been successfully cons...

Cation-disordered ZnGeN2 shows promise for application as a blue-green emitter in light-emitting devices, but more foundational work is necessary to understand structure–property relationships. In this work, we present a combinatorial exploration of the experimental phase space of wurtzite (cation-disordered) ZnGeN2 using high-throughput co-sputtering. Structure, morphology and optical properties are explored as a function of cation composition and synthesis temperature. ZnGeN2 is found to crystallize in the wurtzite structure ranging from Zn-rich to Ge-rich compositions. X-ray diffraction refinements reveal a continuous shift in cell volume with off-stoichiometry, indicating alloy-like structural behavior. The optical absorption of all films examined is lower in energy than the value predicted for cation-ordered ZnGeN2, suggesting that cation disorder is decreasing the bandgap. Additionally, the absorption threshold shifts continuously to higher energy for Ge-rich samples, consistent with bandgap shifts due to alloy-like structural behavior. Defect formation energy diagrams are calculated to help guide understanding of off-stoichiometry from a defect complex perspective. This work paves the way toward use of ZnGeN2 as a bandgap-tunable optoelectronic semiconductor.

Unique Fe and N co-doped multi-walled carbon nanotubes are designed to efficiently catalyze the oxygen reduction reaction (ORR). The preparation processes involve surface functionalization, subsequent wet impregnation and final thermal fixation of Fe-Nx species. The catalyst achieved outstanding alkaline ORR performance with a very positive half-wave potential (∼0.91 V). Theoretical calculations show that the carbon layer below the active Fe-Nx sites is beneficial to the ORR.

The blue thermally activated delay fluorescence (TADF) emitters are highly attractive in the fields of constructing hybrid white organic light-emitting diodes (WOLEDs) due to its high efficiency and color stability. However, few blue TADF emitters can withstand sequential orthogonal solvents, making it impossible to fabricate the fully solution-processed hybrid WOLEDs. Here, two TADF materials, PCz-4CzCN and TPA-4CzCN, were designed and synthesized by equipping the emissive core with nonconjugated bulky units, which can effectively enhance the solvent resistance ability without disturbing the TADF feature. The photophysical investigation indicates that phenylcarbazole unit can efficiently block the electromer formation to enhance the energy transfer and exciton utilization of the emitter. Accordingly, the blue OLEDs of PCz-4CzCN shows higher external quantum efficiency (EQE) of 22.6%, which is the best performance recorded among the fully solution-processed blue OLEDs. Upon further doping, the yellow phosphor PO-01, the fully solution-processed TADF-phosphor (T-P) hybrid WOLEDs was successfully obtained with high performance for the first time. Thanks to the efficient exciplex formation, the turn-on voltage of the white device is only 2.8 V, and the maximum brightness and power efficiency are as high as 53 300 cd m

Despite major advancement in coating graphene layers at material surfaces, challenges still exist towards achieving rapid heating and cooling under low energy consumption. Herein, atmospheric pressure chemical vapor deposition (APCVD) method was adopted to coat carbide-bonded graphene at the surface of zirconia substrate with a 2.7 cm diameter and a 1 cm thickness. The graphene coated zirconia substrate can achieve rapid thermal cycling with as high as approximately 50 °C/s of average heating rate at 150–320 °C temperature range using a low input voltage (12 V) and power (48 W). That is mainly due to the formation of highly qualified graphene and single-wall carbon nanotubes at the carburization layer, which is confirmed by the Raman spectra. The excellent electrothermal response characteristics is expectantly useful for rapid thermal cycling in injection molding thin-wall parts with high processing temperature (higher than 250 °C) under operation safety and low energy consumption, which is obviously absent in this emerging research area.

In this paper, argon was used in radio frequency (13.56 MHz) dielectric barrier discharge (rf-DBD) at atmospheric pressure. The IV curve was recorded after gas breakdown, and discharge photos were captured by ICCD camera. Discharges of α mode and γ mode were observed based on IV curve and ICCD photos. As the existence of negative glow in γ mode, the luminescence intensity of different position of the discharge gap was analyzed. It was found that in the α mode, the electron avalanche occurs from negative to positive and negative glow appeared after the discharge changed into γ mode. In every half cycle, the peak position of negative glow is 13 ± 1 ns later than that of electron avalanche on cathode surface.

In this study, effects of various geometrical parameters of a new winglet longitudinal vortex generator (LVG) on heat transfer and flow characteristics in a rectangular channel were investigated by a numerical method, and the influence of various parameters was analyzed. A comparative study of effects of elliptical pole parameters, the thickness, the length, the height, the attack angle, the transverse pitch and the longitudinal pitch of LVGs on heat transfer and pressure loss performance was conducted. The results showed that the intensity of heat transfer could be greatly increased by the increase of the length, the height, the attack angle and the transverse pitch of LVGs, accompanied with an increase of pressure drop. The Nusselt number decreased by increasing the longitudinal pitch of LVGs. The short axis and major axis of the elliptical poles and the thickness of LVGs had a small influence on the average heat transfer coefficient and average friction factor at the present condition. The design parameters of this configuration were optimized by the Taguchi method. Sixteen kinds of models were made by compounding levels on each factor, and heat transfer and flow characteristics of each model were analyzed. The results allowed us to quantitatively estimate the various parameters affecting heat transfer performance, and the main factors for optimal design of a rectangular channel with LVGs were selected. The optimal condition was also acquired by two analytical results. (Less)

Aiming at the application problem of non-uniform heating on the supercritical boiler, a numerical investigation of non-uniform heating upward circular tube is presented in this paper. The turbulent model k-e (RNG) with enhanced wall treatment is employed after validating against the classic experimental results. Afterwards, the non-uniform heat transfer characteristics and mechanism, the influence factors and the criteria for onset of buoyancy effect on heat transfer of semi-heated tube are analyzed. The simulation results indicate that: (1) for non-uniform heating tube, the temperature distribution of cross section shows a great non-uniformity along the circumference, the heat transfer enhancement only appears in part area of cross section; (2) the key factors such as heated mode, heat flux, constant G/q and pressure are all influential on the thermal performance of non-uniform heating tube; and (3) investigate a good criterion standing out from three criterions to describe the onset of the secondary flow in non-uniform heating tube.

In this paper, an energy balance-based model considering icing effects was established for estimating the heat transfer of submerged combustion vaporizer (SCV) under supercritical LNG pressure, where introduces some empirical correlations to evaluate the convection heat transfer of water bath-side and LNG-side. Based on this model, the thermal performance of a typical SCV was predicted numerically, and good agreement between the predicted and actual water bath temperatures indicates that the model is reliable. The results indicated that the operation parameters, such as LNG pressure, operating load, inlet LNG temperature, have significantly different influences on the thermal performance of SCV, including required minimum water bath temperature and flue gas flow rate, and the length and average thickness of ice layer outside the LNG tube bundle. The heat transfer enhancement techniques can improve the heat transfer efficiency markedly, although they also cause an increase in flow resistance. The wire coil insert with a helix angle of 75° is a better choice than the twisted tape insert with a helix angle of 45° and the wire coil insert with a helix angle of 45° considering its effects on both heat transfer and flow resistance.

In this paper, we employ transmission electron microscopy coupled with energy-dispersive X-ray spectrometry (EDS) to study the structure and chemistry of cadmium telluride (CdTe) thin-film solar cells with different extents of degradation. The studied regions originate from the same photovoltaic mini-module, which was subjected to one-sun light exposure at a temperature of 100 °C for 400 h to induce light and heat degradation. EDS maps reveal a discontinuous CdS layer and particles rich in O and S but Te-depleted within the CdTe absorber layer after the light and heat stress. These features could act as enhanced recombination centers, resulting in decreased photovoltaic conversion efficiency. Additionally, the most degraded CdTe sample shows a strong accumulation of Na precisely localized in the discontinuous part of the CdS layer. The local Na concentration is determined to be ∼16 at.%. In addition, appreciable Na accumulation is observed at the soda-lime glass/transparent conductive oxide interface in both degraded CdTe solar cells. The microstructure of the baseline CdTe mini-module with no stress was also investigated to demonstrate that the structure difference was caused by the light- and heat-induced degradation, instead of module fabrication. These results highlight the need to control the distribution of Na in fielded CdTe modules to sustain long-term high-power output.

The three-dimensional vibration of circular rings coupled by elastic elements is investigated in this paper. The vibration characteristics of a single circular ring are examined first analytically and experimentally and then used as building blocks for a stack of concentric rings connected by elastic insulators, which is used as an approximate-model of a disk-type transformer winding. The key outcomes of this research are a more realistic model for transformer winding vibration and determining its three-dimensional vibration characteristics. The model is also verified experimentally. An experimental-based numerical method is also developed for identifying the stiffness and damping properties of the elastic elements.

Two series of lanthanide phosphonates, [H4BAPEN]1.5·[Ln2(HEDP)3]·5H2O [Ln = Gd3+ (1-Gd), Tb3+ (1-Tb), Dy3+ (1-Dy)] and [H4BAPEN]0.5·[LnLi(HHEDP)2(H2O)2]·2H2O [Ln = Gd3+ (2-Gd), Tb3+ (2-Tb), Dy3+ (2...

A series of CaZnOS: Bi3+, Sm3+, Li+ phosphors are prepared by solid-state reaction method at high temperature in H2/N2 atmosphere. The site occupation of activators and luminescence properties, as well as energy transfer mechanism were investigated in detail. The Ca2+ positions are occupied by the Bi3+ and Sm3+ ions according to the XRD Rietveld refinement. Under the excitation at 366 nm, the CaZnOS: Bi3+, Sm3+, Li+ phosphors show an intense broad emitting band peaking at 490 nm owing to the 3P1,0→1S0 transition of Bi3+, and four red emitting bands within the wavelength range of 550–750 nm which can be assigned to the 4G5/2→6HJ (J = 5/2, 7/2, 9/2 and 11/2) transition of Sm3+. The emission color changes from blue-green to orange-red, and the decay time drastically decreased with increasing Sm3+ concentration, attributing to the energy transfer from Bi3+ to Sm3+. In addition, the co-doped phosphor exhibits better thermal quenching property compared with single activated samples. A cold-white LED was fabricated by using single CaZnOS: Bi3+, Sm3+, Li+ as the wavelength conversion phosphor combined with a UV LED chip, and the obtained LED exhibits the high Ra (88.9) and CCT (8836 K).

Solvated lanthanide (Ln) cations as templates were employed to assist the fabrication of a series of iodocuprates {[Ln(DMSO)7(CH3OH)][Cu5I7]·I}n [Ln = Eu3+ (1), Tb3+ (2), Dy3+ (3)] (DMSO = dimethyl sulfoxide) and {[Ln(DMF)8][Cu8I11]}n [Ln = Eu3+ (4), Tb3+ (5), Dy3+ (6)] (DMF = N,N-dimethylformamide). The obtained materials are equipped with good photoluminescence and magnetic properties by virtue of the functional Ln3+ ions. The synthetic strategy, structural analysis, and properties for these multifunctional materials are discussed in detail. Notably, based on 4 and 5, a Ln-doped iodocuprate {[Eu0.37Tb0.31Tm0.32(DMF)8][Cu8I11]}n (7) was successfully constructed, exhibiting white-light emission at room temperature when excited by UV light, which offers a novel strategy to obtain promising optical function materials. Moreover, the combination of Ln3+ and iodocuprates in this work provides a new way to construct multifunctional molecular materials.

A highly efficient solution-processible TADF blue host is developed by molecular encapsulation. Due to the steric shield effect of the peripheral units, the triplet–triplet and triplet–polaron quenching of the TADF blue host are restricted., Developing a solution-processible blue thermally activated delayed fluorescence (TADF) emitter for hybrid white organic light emitting diodes (WOLEDs) is still a challenge. In this work, two TADF blue emitters are designed and synthesized to explore a common strategy to qualify the small molecular TADF material as a solution-processible blue host. Systematic studies find that the molecular encapsulation by introducing unconjugated carbazoles as steric shields not only keeps the intrinsic TADF feature unchanged, but also effectively suppress the intermolecular interaction induced exciton quenching, which makes the material more efficient for solution-processing. The optimized solution-processed hybrid WOLEDs based on the encapsulated TADF blue host realized a highly efficient device performance with a maximum current efficiency (CE), power efficiency (PE) and external quantum efficiency (EQE) of 45.6 cd A–1, 40.9 lm W–1 and 17.0%, respectively, which are three times higher in device efficiency and twenty times higher in device lifetime than the corresponding device with an unencapsulated TADF blue host. Furthermore, the obtained device exhibits a high electroluminescence (EL) above 20 000 cd m–2 and a stable EL spectrum with nearly unchanged Commission International de L’Eclairage (CIE) coordinate at a wide range of applied voltages. These results clearly demonstrate that the molecular encapsulation of the TADF blue host is a superior and promising strategy to achieve high performance and color stable solution-processed hybrid WOLEDs.

In this communication, we report a new-phase 2M WSe2 with a monoclinic space group C2/m. 2M WSe2 presents a metallic behavior under ambient pressure and shows a superconducting transition with a maximum Tc of 7.3 K at 10.7 GPa, which arises from the enhanced density of states near the Fermi surface upon pressurization.

A pillared-layer strategy is employed to assist the construction of two water-stable Zn-based metal–organic frameworks (MOFs) in this work, [ZnL(Bipy)]·0.5H2O (1) and [ZnL(Bpyb)]·1.5H2O (2) (H2L = 5-(pyridine-4-yl)isophthalic acid, Bipy = 4,4′-bipyridine, and Bpyb = 1,4-bis(pyrid-4-yl)benzene). The linkage of Zn centers and L2− ligands affords the layer structures, which are further pillared by the linear N-donor ligands to the three-dimensional architectures. The “pillars” with diverse molecular lengths lead to different pore sizes in 1 and 2, which show different sorption behaviors for iodine capture. Additionally, the photoluminescence properties of compounds 1 and 2 were investigated. Moreover, the photoluminescence sensing experiment indicates that compound 1 can be considered to be a promising selective sensor for Fe3+.

${\mathrm{ZnGeN}}_{2}$ is sought as a semiconductor with comparable lattice constant to GaN and tunable band gap for integration in optoelectronic devices. Configurational disorder on the cation sublattice of ${\mathrm{ZnGeN}}_{2}$ can strongly modify the electronic structure compared to the ordered material, and both ordered and disordered forms of ${\mathrm{ZnGeN}}_{2}$ are candidates for light-emitting diodes and other emitters. The nonisovalent character of the disordered species (${\mathrm{Zn}}^{2+}$ and ${\mathrm{Ge}}^{4+}$) subjects the cation ordering to strong short-range order effects. To model these effects, we use Monte Carlo (MC) simulations utilizing a cluster expansion to approximate formation enthalpy. Representative disordered configurations in 1024-atom supercells are relaxed in density functional theory calculations. From the MC structures, we extract a short-range order parameter (the N-cation coordination motif), and two long-range order parameters (Bragg-Williams and stretching parameters), and examine their correlations. We perform a thermodynamic integration to determine the mixing entropy and free energy. ${\mathrm{ZnGeN}}_{2}$ exhibits a first-order phase transition with pronounced discontinuities in enthalpy and entropy, as well as in the structural order parameters. We discuss the relationship between the effective temperature used in the MC simulation and the growth temperatures in experiment in relation to the crossover from the nonequilibrium to the equilibrium growth regime. This work expands on current models of site disorder in ${\mathrm{ZnGeN}}_{2}$ and provides atomic structure models with a systematic variation of the degree of cation disorder.

Tunable full-color room temperature phosphorescence (RTP) is charming due to its potentials in multiple anti-counterfeitings, all-color displays, and multichannel biomarkers. However, it is a huge challenge to acquire excitation-dependent continuously adjustable full-color RTP from a single-component compound. Herein, we report two Zn(II)−based organic complexes, which are the first examples that present blue, cyan, green, yellow, orange, and red continuously tunable phosphorescence with decent quantum efficiency in response to variation of excitation energy at ambient conditions. The unique photoluminescence property is induced by multiple triplet decay pathways, i.e. 3ligand-centered* and 3charge transfer*. The population and stabilization of the triplet excitons benefit from heavy atom effect of Br ions and restriction of molecular motion due to crystallization. This work contributes an insight for the construction of full-color RTP materials and endows Zn(II)−based organic complexes with fresh features for extensive applications.

In order to realize the rapid preparation of large-area photonic crystals on the paper surface, this paper combines the coating method and the self-assembly technology of colloidal microspheres to prepare photonic crystals on the paper surface. At the same time, the assembly conditions such as the concentration of colloidal microspheres and black dye are optimized, so that the colloidal microspheres are regularly arranged on the paper substrate, and the color rendering performance of the photonic crystal is improved. The digital cameras and the scanning electron microscope were used to measure the color appearance and micro-morphology of the samples. The X-Rite MA68II multi-angle spectrophotometer was used to measure the reflection spectrum. The rapid coating method overcame the long preparation cycle of the traditional way.