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The present work pertains to experimental studies on the unsteady phenomena in the saturated flow boiling of R407C stemming from the oscillatory refrigerant flow rate with the triangle shape in the horizontal slender annular channel. Attention is mainly paid to examine the effects of different parameters, including mean mass flux, amplitude and period of the oscillating mass flux, saturation temperature of R407C, input thermal flux, and gap size on the boiling diagrams and heat transfer coefficients. Firstly, the steady-state saturated flow boiling is studied as baseline cases. It was concluded that beyond the onset of nucleate boiling region, the mass flux of refrigerant has little influences on the boiling diagrams, which indicates that the fully developed nucleate boiling is the major mechanism. The saturated flow boiling heat transfer coefficient is enhanced as the gap size is reduced. Then, the experiment focuses on the temporal changes in the wall temperature Tw and the heat transfer coefficient hr stemming from oscillatory flow conditions. When the mass flux is oscillated periodically with the triangle shape, the Tw and hr are also oscillated temporally and enhanced with increasing in either the amplitude or frequency of oscillating mass flux. At higher input thermal flux, Tw decreases with the decreasing mass flux, which has opposite tendency compared to the single-phase convection with lower thermal flux. For intermediate exerted thermal flux, there is a negligible oscillation in the Tw and hr for most cases; the amplitudes of oscillations are lower than 0.2 °C. Besides, the significant oscillations in the wall temperature and heat transfer coefficient are noted the case with large period of the oscillating mass flux.

The recombination of charge carriers arriving from the random charge movement in semiconductor photocatalysts greatly limits the practical application of solar-driven H2 evolution. The design of photocatalytic systems with spatially oriented charge-transfer is a promising route to achieve high charge-separation efficiency for photocatalysts. Herein, novel sea-urchin-like ReS2 nanosheet/TiO2 nanoparticle heterojunctions (SURTHs) are constructed. The unique sea-urchin-like structure endows the ReS2 cocatalyst with an unusual charge edge-collection effect, which leads to a significant acceleration of charge separation and transfer, as evidenced by the well-designed selective photodeposition of Pt quantum dots in SURTHs. The markedly improved charge transfer capacity contributes to a high photocatalytic H2 evolution rate of 3.71 mmol h−1 g−1 for SURTHs (an apparent quantum efficiency (AQE) of 16.09%), up to 231.9 times by contrast with that of P25 TiO2. This work would provide a new platform for designing the high-efficiency cocatalyst/photocatalyst system with excellent charge transfer capacity. This work was funded by the China Postdoctoral Science Foundation (pre-station, No. 2019TQ0050), Applied Basic Research Program of Sichuan Province (No. 2020YJ0068), the China Postdoctoral Science Foundation (No. 2020M673186), National Natural Science Foundation of China (No. 22002014), the Applied Basic Research Program of Sichuan Province (No. 2020ZYD014). Thanks for the technical help from Sichuan Province Key Laboratory of Display Science and Technology, State Key Laboratory of Electronic Thin Films and Integrated Devices. Dr. Xiao Luo acknowledges financial support from the National Natural Science Foundation of China (No. 21903084) and Applied Basic Research Program of Sichuan Province (No. 2021YJ0408). Dr. Qing Liu acknowledges financial support from the National Natural Science Foundation of China (No. 52002051) and the Fundamental Research Funds for the Central Universities, SCUT (No. ZYGX2020J009).

Low-efficiency charge transfer is a critical factor to limit the photocatalytic H2 evolution activity of semiconductor photocatalysts. The interface design is a promising approach to achieve high charge-transfer efficiency for photocatalysts. Herein, a new 2D/2D atomic double-layer WS2/Nb2O5 shell/core photocatalyst (DLWS/Nb2O5) is designed. The atom-resolved HAADF-STEM results unravel the presence of an unusual 2D/2D shell/core interface in DLWS/Nb2O5. Taking advantage of the advanced femtosecond-resolved ultrafast TAS spectra, the average lifetime of charge carriers for DLWS/Nb2O5 (180.97 ps) is considerably shortened as compared to that of Nb2O5 (230.50 ps), strongly indicating that the 2D/2D shell/core interface enables DLWS/Nb2O5 to achieve ultrafast charge transfer from Nb2O5 to atomic double-layer WS2, thus yielding a high photocatalytic H2 evolution rate of 237.6 μmol/h, up to 10.8 times higher than that of pure Nb2O5 nanosheet. This study will open a new window for the development of high-efficient photocatalytic systems through the interface design.

The differences in the microstructure and elevated temperature tensile properties of gravity die cast, squeeze cast, and semi-solid thixoformed Al–Si–Cu–Mn–Fe alloys after thermal exposure at 300 °C were discussed. The results demonstrate that the elevated temperature tensile properties of semi-solid thixoformed alloys were significantly higher than those of gravity die cast and squeeze cast alloys, especially after thermal exposure for 100 h. The ultimate tensile strength (UTS) of semi-solid thixoformed alloys after thermal exposure at 300 °C for 0.5, 10 and 100 h were 181, 122 and 110 MPa, respectively. The UTS values of semi-solid thixoformed alloys were higher than those of heat resistant aluminum alloys used in commercial applications. The enhanced elevated temperature tensile properties of semi-solid thixoformed experimental alloys after thermal exposure can be attributed to the combined reinforcement of precipitation strengthening and grain boundary strengthening due to thermally stable intermetallic phases as well as suitable grain size.

Plate-like Fe-rich intermetallic phases directly influence the mechanical properties of recycled Al alloys; thus, many attempts have been made to modify the morphology of these phases. Through synchrotron X-ray imaging and electron microscopy, the underlying nucleation and growth mechanisms of Fe-rich phases during the solidification of Al-5Ti-1B-modified Al-2Fe alloys were revealed in this study. The results showed that the Al-5Ti-1B grain refiner as well as the applied pressure both resulted in reduction of the size and number of primary Al3Fe phases and promoted the formation of eutectic Al6Fe phases. The tomography results demonstrated that Al-5Ti-1B changed the three-dimensional (3D) morphology of primary Fe-rich phases from rod-like to branched plate-like, while a reduction in their thickness and size was also observed. This was attributed to the fact that Ti-containing solutes in the melts inhibit the diffusion of Fe atoms and the Al3Fe twins produce re-entrant corner on the twin boundaries along the growth direction. Moreover, the TiB2 provides possible nucleation sites for Al6Fe phases. The nucleation mechanism of Fe-rich phases is discussed in terms of experimental observations and crystallography calculations. The decrease in the lattice mismatch between TiB2 and Al6Fe phases was suggested, which promoted the transformation of Al3Fe to Al6Fe phases.

The nacre-inspired Al-Si/TiB2 composites were successfully prepared by freeze casting and pressure infiltration. The microstructures and mechanical properties of nacre-inspired Al-Si/TiB2 composites were studied by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and mechanical testing. The results show that the high performance of Al-Si/TiB2 composites can be attributed to the clean interfaces between TiB2 and Al and several toughening mechanisms, such as crack blunting, crack branching, crack deflection, plastic deformation of Al layer, and bridging of the uncracked fracture process zone. Specifically, the compressive strength, three-point bending strength and KIC of composites corresponding to LS were 640–710 MPa, 629 MPa, and 16.4 MPa m1/2, respectively. The fracture behaviors of the Al-Si/TiB2 composites have been discussed in detail in this work. It was found that single cracks were accompanied by the propagation of multiple micro-cracks in the layered composites. The precipitation of Si particles at the TiB2/α-Al interface and the Al phases infiltrated in the TiB2 layers play a great role in the formation of single crack fractures and multiple micro-cracks fractures, respectively, in the nacre-inspired Al-Si/TiB2 composites.

The motion of organic cations and its possible correlation with excited state photodynamics are important to the fundamental understanding of the superior performances of 2D and 3D hybrid lead-halide perovskites (LHPs) in optoelectronic applications. Herein, variable-temperature (VT) solid-state 1H and 13C CP (Cross Polarization) NMR spectroscopy without isotope enrichments, combined with VT powder XRD, differential scanning calorimetry (DSC) and time-resolved photoluminescence (TRPL), was employed to study the phase transition, local structure, motion dynamics and photodynamic behaviors of organic cations in hybrid 2D Ruddlesden-Popper perovskites (BA)2(MA)n-1PbnI3n+1 (BA denotes butylammonium and MA denotes methylammonium). Two types of BA conformations in various crystalline phases of 2D RPPs and conformational transition associated with phase transition were clearly revealed. Quantitative NMR analyses suggest that the rotation dynamics of MA in 2D RPPs is comparable to that of MA in 3D MAPbI3. A surprising linear relationship was discovered between the estimated activation energy of the MA rotation and logarithm of photoluminescence (PL) lifetimes (τ) of 2D RPPs and MAPbI3, strongly supporting the presence of coupling between the cation spatial dynamics and the excited state photodynamic behavious.

Recent discoveries of two-dimensional transitional metal based materials have emerged as an excellent candidate for fabricating nanostructured flame-retardants. Herein, we report an eco-friendly flame-retardant for flexible polyurethane foam (PUF), which is synthesised by hybridising MXene (Ti$$_3\hbox {C}_2$$ 3 C 2 ) with biomass materials including phytic acid (PA), casein, pectin, and chitosan (CH). Results show that coating PUFs with 3 layers of CH/PA/Ti$$_3\hbox {C}_2$$ 3 C 2 via layer-by-layer approach reduces the peak heat release and total smoke release by 51.1% and 84.8%, respectively. These exceptional improvements exceed those achieved by a CH/Ti$$_3\hbox {C}_2$$ 3 C 2 coating. To further understand the fundamental flame and smoke reduction phenomena, a pyrolysis model with surface regression was developed to simulate the flame propagation and char layer. A genetic algorithm was utilised to determine optimum parameters describing the thermal degradation rate. The superior flame-retardancy of CH/PA/Ti$$_3\hbox {C}_2$$ 3 C 2 was originated from the shielding and charring effects of the hybrid MXene with biomass materials containing aromatic rings, phenolic and phosphorous compounds.

The n-octadecyltrichlorosilane (OTS) had been coated onto the layered double hydroxides (LDH), and the resultant composite of OTS-LDH was further loaded on the surface of melamine sponge by a soaking method to obtain the OTS-LDH/melamine sponge for efficient oil adsorption in this work. The surface chemical compositions of the OTS-LDH/sponge and its precursors were characterized by EDS, XPS, and FTIR. The results from EDS, XPS, and FTIR showed that the OTS had been successfully coated on LDH. The surface morphologies from SEM for the melamine sponge before and after modification illuminated that the surface skeleton of the OTS-LDH/sponge took a rough micro-nanostructure, and the surface had been loaded with the low surface energy material of OTS, which made the OTS-LDH/sponge display the superhydrophobic properties. The experiments of oil–water separation proved that the OTS-LDH/sponge took an excellent oil–water efficiency, and the modified sponge still took the better oil–water separation performance with an oil adsorption capacity of 13.7–21.1 times of the mass of the pristine sponge even after undergoing repeated extrusion for 60 times during the repeated cycle test.

Cocatalyst design is a key approach to acquire high solar-energy conversion efficiency for photocatalytic hydrogen evolution. Here a new in situ vapor-phase (ISVP) growth method is developed to construct the cocatalyst of 2D PtS nanorectangles (a length of ∼7 nm, a width of ∼5 nm) on the surface of g-C3N4 nanosheets. The 2D PtS nanorectangles/g-C3N4 nanosheets (PtS/CN) show an unusual metal sulfide–support interaction (MSSI), which is evidenced by atomic resolution HAADF-STEM, synchrotron-based GIXRD, XPS and DFT calculations. The effect of MSSI contributes to the optimization of geometrical structure and energy-band structure, acceleration of charge transfer, and reduction of hydrogen adsorption free energy of PtS/CN, thus yielding excellent stability and an ultrahigh photocatalytic H2 evolution rate of 1072.6 μmol h−1 (an apparent quantum efficiency of 45.7% at 420 nm), up to 13.3 and 1532.3 times by contrast with that of Pt nanoparticles/g-C3N4 nanosheets and g-C3N4 nanosheets, respectively. This work will provide a new platform for designing high-efficiency photocatalysts for sunlight-driven hydrogen generation.

A superoleophilic polyurethane sponge had been constructed by means of an immersion method in an ethanol solution of n-octadecyltrichlorosilane. SEM, FTIR, TGA, and XPS unanimously confirmed that PODS had been successfully coated onto the skeleton of polyurethane sponge. The PODS-modified sponge displayed both excellent hydrophobicity with high water contact angle of 152° and good oil affinity. The PODS-modified sponge took the high adsorptive capabilities for the silicone oil, toluene, and peanut oil with 62.1, 73.7, and 98.2 g · g–1 after 50 cycles of extrusion-release, respectively. The superoleophilic sponge in this work exhibited promising opportunities on the oil/water separation and the oil spill remediation.

The modifications of impeller may show diverse impact on centrifugal pump operating in pump and turbine modes. To clarify this problem, the hydraulic performance of a low specific speed centrifugal pump operating in both modes was firstly obtained by CFD method and verified by experiment. Then, based on the single-factor design method, a series of calculations have been conducted to identify the effects of impeller geometry parameters on the hydraulic performance in different modes. The variations of head, shaft power and hydraulic efficiency curves with different impeller parameters were explored. It is found that compared with turbine, the pump shows a more obvious variation of head. The outlet angle has positive impact both on the head consumed by pump or generated by turbine. The change of turbine shaft power is apparently smaller than that of pump for different impeller geometry parameters. Only the outlet width somewhat changes the turbine shaft power. The hydraulic efficiency in both modes shows different variation under different impeller geometric parameters, while the hydraulic efficiency of both modes is reduced with the outlet angle increasing. Meanwhile, the response amount of hydraulic efficiency caused by certain change of impeller parameters was estimated by sensitivity analysis method. It is found that only the appropriate blade number and outlet width can improve the hydraulic performance both in pump and turbine modes. Eventually, the hydraulic loss, skin friction loss and theoretical analysis were performed to explore the reason of hydraulic performance variation due to different impeller parameters. The change of slip factor, impeller inlet area, impeller outlet area or hydraulic loss results in the change of hydraulic performance in both modes. The results can be useful for hydraulic performance improvement for both pump and turbine modes through impeller geometry modification.

Fiber-reinforced polymer composite laminate is weak in the Z-direction, which limits its application. Herein, short carbon fiber (SCF) was decorated with graphene oxide (GO) to form GO@SCF, which was used to improve epoxy matrix and thereby the interlaminar shear strength (ILSS) of carbon fiber fabric (CFF)-reinforced epoxy composites. The effect of GO@SCF on the ILSS of the composite has been examined. It showed that the optimal content of GO@SCF was 0.1 wt%, and the maximum value of ILSS reached 59.4 MPa, which was 14.7% higher than the pure CFF/epoxy composite. The neat SCF was also employed to enhance the ILSS for the purpose of comparison. The results indicate that GO@SCF has better effect on reinforcing the ILSS than the neat SCF. This study provides an effective approach for the reinforcement of the ILSS of CFF-reinforced epoxy composites.

The effect of surface tensile strain on the photocatalysis is an open question. In this work, strain engineering has been demonstrated to promote the performance of photocatalysis by curved 2D mate...

A N-doped rice husk-based porous carbon (N-RHPC) was cost-effectively prepared by simply treating RHPC at high temperature in an ammonia atmosphere. Results show that the mesopore volume and degree of graphitization of N-RHPC are significantly increased by the treatment. N atoms are doped in the RHPC structure in the form of pyridinic N (398.5 ± 0.1 eV), pyridonic N (399.3 ± 0.1 eV), and graphitic N groups (401.1 ± 0.1 eV) and N-oxide (401.8 ± 0.1 eV). Compared with a commercial Pt/C catalyst, the N-RHPC as an oxygen reduction electrocatalyst has a similar electrocatalytic activity, and better sTableility and methanol toxicity resistance. This excellent performance is ascribed to the increased number of catalytic sites afforded by the nitrogen species, the improved degree of graphitization that increases electron transfer, and the unique pore structure with macropores, mesopores and micropores for fast ion transport.

In this study, the phase change paraffin and metal powder were mixed to form the composite phase change energy-storing material. This composite material was then injected into metal coil tubings at different coil spacings to form a composite phase change energy storage tubing system, which was then embedded in a wall. The thermal performance of the embedded phase change energy storage wall was investigated at various temperatures. The results showed that among the four types of aforementioned walls, the energy storage tubes at a spacing of 20 mm exhibited the smallest heat transfer and the largest surface heat storage coefficients. Therefore, this wall can block heat flow and temperature propagation effectively, and it exhibits excellent thermal insulating and heat storage performances and increased resistance to temperature fluctuations.

Laser surface melting (LSM) were successfully applied in in-situ 10 vol% ZrB2(np)/6061Al composites. Formation of nano-sized ZrB2 phase is confirmed by FESEM, EDS and HRTEM. Due to the minimization of porosity defects, one-way laser scanning is evaluated as optimum scan route strategy. After LSM, nanoparticle aggregations in composites are largely eliminated by melt vortex and matrix grain growth pushing force. Nanoparticles are uniformly dispersed near matrix grain boundaries and agglomerations showed an explosive orientation dispersion. After LSM, the average matrix grain size decreased by 87.5% to 3.4 μm. Nanoparticle dispersion uniformity and toughness of composites are proportional to laser power density. Both strength and elongation are enhanced as the matrix grain refinement and better uniformity of the nanoparticle dispersion after LSM. When LSM for 420 NW/mm2 was performed, the optimal improvements of tensile strength and elongation are 33.54% and 72.51% respectively.

In order to study the dynamic characteristics of an innovative underwater structure, Submerged Floating Tunnel (SFT), a model test study was carried out in a calibrated experimental tank based on the Qiongzhou Strait cross-sea passage project and considering the effects of wave and current loads. The size of the test tank is 36m (length) x 31m (width) x 3m (depth), which can simulate the effect of wave and current simultaneously. Under the conditions of pure current, pure wave and wave-current coupling, the pressure change of the test pipe is monitored, and the influence of the wave-current load on the surface pressure of the test pipe is analyzed. The experimental results show that the pressure at the inlet side of the test pipe increases with the increase of the current velocity, the wave height and period, regardless of whether the test pipe section is subjected to pure current, pure wave or wave-current coupling.

The effect of Cu and Ti contents and thermal exposure on the elevated temperature mechanical properties of T6-treated Al-Si-Cu-Mn-Fe alloys was investigated via optical microscopy (OM), scanning electron microscope (SEM), transmission electron microscopy (TEM), and elevated temperature tensile tests. The mechanical properties at elevated temperature increased with the increase in Ti and Cu contents. These results can be attributed to the increased amounts of precipitated particles. Thermal exposure at 300 °C for 10 h had a deleterious effect on the elevated temperature tensile properties due to the coarsening of the strengthening precipitates. Further thermal exposure up to 100 h only resulted in a little reduction in the strength. After thermal exposure at elevated temperature of 300 °C, the 4Cu-0.5Ti demonstrated best mechanical properties and Quality Index (QI). The ultimate tensile strength (UTS) at elevated-temperature of 300 °C were 170 MPa, 92 MPa, and 88 MPa for 0.5 h, 10 h, and 100 h after thermal exposure, respectively, which are superior to those for the commercial aluminum alloys. Keywords: Al-Si-Cu-Mn-Fe alloys, Heat resistant intermetallics, Elevated temperature mechanical properties, Thermal exposure

Artificial photosynthetic systems store solar energy in chemical fuels via CO2 reduction or renewable hydrogen evolution from water splitting. But only relatively moderate CO2-reducing solar-to-fuel efficiency (ηSTF < ca. 18%) was achieved previously even using the most active gold-based electrocatalyst for the CO2 reduction reaction (CO2RR), which is much lower than the current highest solar-to-hydrogen efficiency (ηSTH = 30%). Here, we report a strategy based on a monolithic nanoporous silver-based membrane electrocatalyst (npm-Ag) to increase the density of active sites while breaking the three-phase diffusion-limit length of previous membrane electrodes, improving the effective thickness of the catalyst layer from tens of nanometers to several micrometers without any polymer additive. The npm-Ag showed exceptionally selective reduction of CO2 to CO at low overpotentials (ca. 80%@40 millivolts, ca. 100%@90–290 millivolts). The catalyst also allowed a nearly full use of the photocurrent of the state-of-the-art solar cells and gave a projected maximum ηSTF of ca. 25%. Combined with a NiFe-based O2-evolving anode, a stable CO2-reducing photosynthetic system with an ηSTF of ca. 20.1% was demonstrated experimentally for 28 hours in the absence of a DC/DC converter.

The phase morphologies and phase transitions of dendrimer block copolymer thin films confined between two homogeneous, planar hard substrates had been investigated by a three-dimensional real space self-consistent field theory (SCFT). From the perspectives of property and strength of the preferential substrate, when the film system confined within neutral substrates, the thinner film was easier to take the undulated and perpendicular cylinder phases. For the attractive preference of the substrate on block segment A, the polymer films tended to take the surface-wetting structures that was composed by block segment A. On the contrary, for the repulsive preference of the substrate on block segment A, a phase transition of cylinder-lamellae could be observed increasing with the relative surface strength of the preferential substrate.

The reinforcing effect of graphene oxide (GO) in enhancing the flexural strength and flexural modulus of aramid fiber (AF)/epoxy composites were investigated with GO-AFs at a weight fraction of 0.1-0.7%. The flexural strength and flexural modulus of the composite reached 87.16 MPa and 1054.7 MPa, respectively, which were about 21.19% and 40.86% higher than those of the pure epoxy resin, respectively. In addition, the flexural properties and interfacial shear strength (IFSS) of composite reinforced by GO-AFs were much higher than the composites reinforced by AFs due to GO improved the interfacial bonding between the reinforcement material and matrix.

The effect of Ti content on the microstructure and mechanical properties of heat-treated Al–Si–Cu–Mn–Fe alloys was investigated. It was found that the mechanical properties increased with the incre...

Room temperature Na-ion batteries (SIBs) show great potential for use as renewable energy storage systems. However, the large-scale application of SIBs has been hindered by the lack of an ideal SIBs anode material. We synthesized MoS2 on carbonized graphene-chitosan (G-C) using the hydrothermal method. The strong interaction between the MoS2 and the G-C greatly improved the electron transport rate and maintained the structural stability of the electrode, which lead to both an excellent rate capability and long cycle stability. The G-C monolith was proven to enhance the electrical conductivity of the composites and served as a matrix for uniformly dispersing active MoS2 nanosheets (NSs), as well as being a buffer material to adapt to changes in volume during the cycle. Serving as an anode material for SIBs, the MoS2-G-C electrode showed good cycling stability (527.3 mAh g−1 at 100 mA g−1 after 200 cycles), excellent rate capability, and a long cycle life (439.1 mAh g−1 at 1A g−1 after 200 cycles). Keywords: Na-ion batteries, Carbon-based materials, MoS2, Long cycle life

Graphene is well known for its extraordinary mechanical properties combining brittleness and ductility. While most mechanical studies of graphene focused on the strength and brittle fracture behavior, its ductility, plastic deformation, and the possible brittle-to-ductile transition, which are important for high-temperature mechanical performance and applications, still remain much less understood. Here the mechanical response and deformation dynamics of graphene grain boundaries are investigated through a phase field crystal modeling, showing the pivotal effects of temperature and local dislocation structure. Our results indicate that even at relatively high temperature (around 3350 K), the system is still governed by a brittle fracture and cracking dynamics as found in previous low-temperature experimental and atomistic studies. We also identify another type of failure dynamics with low-angle grain boundary disintegration. When temperature increases a transition to plastic deformation is predicted. The appearance of plastic flow at ultrahigh temperature, particularly the phenomenon of jerky plasticity, is attributed to the stick and climb-glide motion of dislocations around the grain boundary. The corresponding mechanism is intrinsic to two-dimensional systems, and governed by the competition between the driving force of accumulated local stress and the defect pinning effect, without the traditional pathways of dislocation generation needed in three-dimensional materials., 39 pages, 15 figures

A low-cost polyethylene terephthalate fluidic sensor (PET-FS) is demonstrated for the concentration variation measurement on fluidic solutions. The PET-FS consisted of a triangular fluidic container attached with a birefringent PET thin layer. The PET-FS was injected with the test liquid solution that was placed in a common path polarization interferometer by utilizing a heterodyne scheme. The measured phase variation of probe light was used to obtain the information regarding the concentration change in the fluidic liquids. The sensor was experimentally tested using different concentrations of sodium chloride solution showing a sensitivity of 3.52 ×104 deg./refractive index unit (RIU) and a detection resolution of 6.25 × 10−6 RIU. The estimated sensitivity and detection resolutions were 5.62 × 104 (deg./RIU) and 6.94 × 10−6 RIU, respectively, for the hydrochloric acid. The relationship between the measured phase and the concentration is linear with an R-squared value reaching above 0.995.

With the recent developments of composite polymer materials, the usage of synthetic materials in interior furnishing has rapidly increased. Polymeric foams such as polyurethane (PU) and polyethylene (PE) are widely applied as upholstered furniture and wall insulations. Nevertheless, the occurrence of fire in a confined environment surrounded by combustible polymeric materials can lead to disastrous consequences. This is because the toxic emission of polymers, specifically carbon monoxide (CO), is responsible for most deaths and injuries in building fires. Thus, it is essential to gain an in-depth understanding of material flammability and gaseous product emissions, as well as the correlation against various radiant heat fluxes, temperatures and ventilation conditions. In this study, cone calorimeter with Fourier Transform Infrared Spectroscopy (FT-IR) was performed on PU, PE and Ethylene–vinyl acetate (EVA) foam to (i) characterise the critical combustion performances; and (ii) obtain real-time emission profiles of asphyxiant gases such as hydrogen cyanide (HCN), formaldehyde (HCHO), and acrolein, under flaming conditions. Furthermore, a fire dynamics simulator (FDS) model was constructed to study the burning characteristics of the selected materials numerically. Furthermore, the in-depth heat and mass transfer involved during the various development stages of the fire are studied via simulation results.

The dynamic recrystallization behaviors of 6082 aluminum alloy in the temperature range of 623–773 K and strain rate range of 0.01–5 s−1 were studied by electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM). According to the experimental results, dynamic recrystallization occurs during hot deformation of 6082 aluminum alloy, although the true stress-strain curve has no obvious single peak characteristic, and the degree of dynamic recrystallization is closely related to the Z parameter. Hot compression with lnZ = 24.9014 (723 K, 0.1 s−1) gives rise to the highest recrystallization fraction of 38.6%. The initial critical strain of dynamic recrystallization was determined by the work hardening rate. The quantitative relationship between the critical strain and Z parameters was established: [Formula: see text]. Based on the EBSD analysis and measurement results, dynamic recrystallization kinetics models of 6082 aluminum alloy during hot deformation were deduced. Microstructure analysis showed that the subgrain structure formed in the original grain is coarsened by grain boundary migration, and the orientation difference increases continuously until a large-angle grain boundary forms, resulting in dynamic recrystallization of grains. The likely mechanism is continuous dynamic recrystallization.

The existence of photonic band gap (PBG) in amorphous networks has been associated with structural short-range order and internal similarity. In this study we present amorphous networks that possess low degrees of orderness and similarity, yet still exhibit decent PBG forming ability. The robustness of PBG is found to be related to less-deviated ring distributions. We develop regional ring disorder to quantify variations of rings, revealing the complementary roles of regional ring uniformity and local similarity in PBG formation. The evolution of PBG with respect to structural deformation is also presented to elucidate the effect of regional characters on PBG formation. Our study brings new insights towards the understanding of PBG formation in amorphous structures, paving the way for novel design and manipulation of amorphous PBG materials.

A secondary master batch process had been applied to design a polyolefin encapsulant material for photovoltaic modules, in which the polymer blend was composed of polyolefin elastomer (POE) and linear low-density polyethylene (LLDPE) with the addition of the cross-linking agent of tert-butylperoxy 2-ethylhexyl carbonate (TBEC) and silane coupling agent of γ-methacryloxypropyl trimethoxy silane (KH570). The rheological property from Haake torque rheometer illuminated that the chemical cross-linking reaction could take place between the POE and TBEC. The LLDPE was added for further increasing the cohesion of polymer blend by obtaining much more physical cross-linking points from the physical entanglement between the flexible chains of LLDPE and the amorphous zone of POE. However, the transmittance of polymer blend ran down with the rise of LLDPE content within the polymer blend. The number and site of melting points of polymer blend by the DSC analysis show that there was compatibility between the POE and LLDPE within the polymer blend; meanwhile, the resultant molecular structures of the polymer blend also had been explained by the FTIR spectra. These results unanimously illuminated that it was a feasible solution for fabricating the polyolefin encapsulant material for photovoltaic modules.

Machine tools may be affected by room temperature, the heat generated by the process, and many other factors. These cause the temperature of the spindle, motor, lead screw, and other parts to rise, and this causes thermal deformation. The main purpose of this study was an exploration of the relationship between the temperature of the spindle and thermal deformation. Measurements were made of the increases in temperature of a CNC lathe spindle, and the related axial displacements involved, at spindle speeds of 1000, 2000, and 3000 rpm. Multiple regression analysis and a general regression neural network were used to establish the relationship between thermal deformation and temperature change individually. The results showed the coefficient of determination of the multiple regression analysis to be 0.9275, while the general regression determined by the neural network was 1. The fitting result of the regression neural network was better than that of multiple regression analysis, and the maximum error was less than 0.1 μm. In addition, this study also used COMSOL simulation analysis software to analyze features of the thermal behavior generated by the spindle structure. A trial and error method was used to adjust the boundary conditions. Results showed that the maximum error in temperature rise determination of simulation and experiment was less than 1 °C.

A novel nerve conductor made out of polypyrrole (PPY), collagen (Coll) and nano-strontium substituted bioactive glass (n-Sr@BG) (PPY/Coll/n-Sr@BG) was fabricated by electrospinning. SEM demonstrated that the mean distances across of the pores in the nerve channels were under 15 mm and more prominent than 2 mm. These biocomposite films had biomimetic morphology, bigger porosity and moderately higher surface territory than customary nerve channels, consequently not just allowing the transportation of nerve development factor and glucose yet, in addition, hindering the section of lymphatic tissue and fibroblasts. The consistent filaments of the nerve can copy the characteristic ECM, which is valuable to cell bond, cell multiplication, and cell movement. PPY/Coll/n-Sr@BG demonstrated great cell fondness rate, which is useful for neurilemma cell cells bond, relocation and expansion. Its great viability empowers its wellbeing animal models. Sciatic nerve deformity was crossed over an animal model with PPY/Coll/n-Sr@BG in rodents. PPY/Coll and autotransplants were utilized as control gatherings. Contrasted with PPY/Coll and PPY/Coll/n-Sr@BG accomplished fundamentally increasingly viable recovery of sciatic nerve wounds following 24 weeks implantation and the mean distance across of muscle fibres occasions bigger than that in PPY/Coll/n-Sr@BG, and it was nearer to that in control. The rejuvenated nerve filaments in PPY/Coll/n-Sr@BG had an increasingly standard round shape, the thickness of neuro-filaments in c was more than those in PPY/Coll, and was near that in control.

Atomic force microscope (AFM) is a high-precision instrument to research surface topography of various samples. Nevertheless, the standard AFM procedure takes excessively long time to acquire high-resolution images. Moreover, too much interaction between a probe tip and a specimen potentially leads to tip abrasion and sample damage. Compressive sensing (CS) has been employed to realize high-speed AFM (HS-AFM). However, a considerably large-sized image may be hard to be reconstructed through the common CS method with some ordinary algorithms, due to the high computational complexity and hardware costs. Thus, block-based compressive sensing (BCS) is adopted as an alternative means. In our work, three scanning patterns were utilized to generate undersampled AFM images at various sampling rates for five samples with different surface appearance. Each image block was reconstructed through one of six representative algorithms. Finally, an optimal measurement scheme for BCS-HS-AFM was put forward based on the analysis of experimental results, which consisted of sampling rate, scanning pattern, block mode and reconstruction algorithm. BCS was compared with other CS methods in terms of the computational complexity and image reconstruction effect to reveal its superior performance. In brief, BCS can be applied to effectively realize the high-resolution and low-damage HS-AFM imaging.

The effect of Si content on the microstructures and mechanical properties of the heat-treated Al–6.5Cu–0.6Mn–0.5Fe alloy was investigated using image analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile testing. The results show that the mechanical properties of Al–6.5Cu–0.6Mn–0.5Fe alloys decrease slightly when the Si content is below 1.0%. This can be attributed to the comprehensive effect of microstructure evolution, including the increase of nano-sized α-Fe, the coarsened grain size, and an increase in Al2Cu content at the grain boundary. When the Si content is 1.5%, the mechanical properties of the Al–6.5Cu–0.6Mn–0.5Fe alloys decrease significantly, and this can be attributed to the agglomerated second intermetallics, which is resulted from the formation of excess Si particles.

In order to make better use of the low ash fusion temperature semi-coke, increasing the coal’s ash fusion temperature is the key to improving the coal gasification process. In this paper, through c...

A remarkable recent advancement has been the successful synthesis of two-dimensional boron monolayers on metal substrates. However, although up to 16 possible bulk allotropes of boron have been reported, none of them possess van der Waals (vdW) layered structures. In this work, starting from the experimentally synthesized monolayer boron sheet (β12 borophene), we explored the possibility for forming vdW layered bulk boron. We found that two β12 borophene sheets cannot form a stable vdW bilayer structure, as covalent-like B–B bonds are formed between them because of the peculiar bonding. Interestingly, when the covalently bonded bilayer borophene sheets are stacked on top of each other, three-dimensional (3D) layered structures are constructed via vdW interlayer interactions, rather than covalent. The 3D vdW layered structures were found to be dynamically stable. The interlayer binding energy is about 20 meV/Å2, which is close to the weakly bound graphene layers in graphite (∼16 meV/Å2). Furthermore, the density functional theory predicted electronic band structure testifies that these vdW bulk boron crystals can behave as good conductors. The insights obtained from this work suggest an opportunity to discover new vdW layered structures of bulk boron, which is expected to be crucial to numerous applications ranging from microelectronic devices to energy storage devices.

In a “thermally decoupled” PV/T system, photovoltaic and thermal absorbers are allowed to operate at different temperatures to utilize full-spectrum sunlight. In this study, a two-axis tracking PV/T system with a SiO2/TiO2 interference thin film (irradiated by natural sunlight) was designed and fabricated initially. The SiO2/TiO2 interference thin film designed by the authors achieved a high average reflectance (R ≥ 96.8%) for PV bands, with a high average transmittance (T ≥ 85%) at 1100–2500 nm. The photoelectric, photothermal, and overall efficiencies were tested and analyzed theoretically using the first and second laws of thermodynamics. Outdoor testing indicated that PV cells with SiO2/TiO2 interference thin film can decrease by 3.0 K, and that the power generation and efficiency of the PV cells can be improved by 10% and 0.65%, respectively. The overall energy and exergy efficiency of the PV/T system based on SiO2/TiO2 interference thin film can reach 22.72% and 18.81%, i.e., 4.94% and 1.03% higher than those without a SiO2/TiO2 interference thin film, respectively. The calculated payback time was 17 years for this PV/T system.

Ti−47Al−2Nb−2Cr−0.15B (mole fraction, %) alloy was vacuum brazed with amorphous and crystalline Ti−25Zr− 12.5Cu−12.5Ni−3.0Co−2.0Mo (mass fraction, %) filler alloys, and the melting, spreading and gap filling behaviors of the amorphous and crystalline filler alloys as well as the joints brazed with them were investigated in details. Results showed that the amorphous filler alloy possessed narrower melting temperature interval, lower liquidus temperature and melting active energy compared with the crystalline filler alloy, and it also exhibited better brazeability on the surface of the Ti−47Al−2Nb−2Cr−0.15B alloy. The TiAl joints brazed with crystalline and amorphous filler alloys were composed of two interfacial reaction layers and a central brazed layer. Under the same conditions, the tensile strength of the joint brazed with the amorphous filler alloy was always higher than that with the crystalline filler alloy. The maxmium tensile strength of the joint brazed at 1273 K with the amorphous filler alloy reached 254 MPa.

The relatively low charge transfer efficiency remains the critical limiting factor for the practical application of solar-driven water splitting. In this work, a promising photocatalyst intensified by dual cocatalysts was developed via separately loading Au nanoparticles and CoP nanosheets onto the inside and outside surface of three dimensionally ordered macroporous (3DOM) g-C3N4 framework to significantly facilitate the ordered transfer of charges. The spatial positioning of dual cocatalysts and average wall thickness of 3DOM g-C3N4 framework were precisely controlled to reveal the optimal distribution position of Au and CoP as well as the most appropriate transfer distance for charges (from 3DOM g-C3N4 walls to the surface of cocatalysts), respectively. The results show that the spatial positioning effect of dual cocatalysts and optimization of charge transfer distance can endow the CoP/3DOM g-C3N4/Au photocatalyst with an excellent charge transfer efficiency, thereby contributing to high apparent quantum efficiency (AQE, 27.6% at 435 nm and 29.9% at 550 nm) and photocatalytic H2 evolution activity of 11,820.1 μmol h−1 g−1, which is up to 619.9, 6.5 and 5.6 times than that of 3DOM g-C3N4, CoP/3DOM g-C3N4 and 3DOM g-C3N4/Au, respectively. This work would provide a new platform to design high-performance artificial photocatalysts with superior charge transfer capacity.

In the present work, the surface-modified graphene (SMG)/poly(vinylidene fluoride) (PVDF) fibrous membranes obtained from the electrospinning were treated by the hot pressing in the laminating mode to form the SMG/PVDF composites. The SMG was prepared by subjecting the graphene oxide to silane modification, NaBH4 reduction, and PVDF grafting in sequence. The successful surface modification of graphene was confirmed by TEM, XPS, Raman spectroscopy, FTIR, WAXD, and TGA. Furthermore, the structures of SMG/PVDF composites fabricated by the electrospinning-hot pressing method were studied by SEM, FTIR, and WAXD, which exhibited the well dispersion of SMG in the PVDF matrix. Finally, the investigation showed that the dielectric permittivities of SMG/PVDF composites increased with the SMG content, which were significantly higher than that of pristine PVDF. The dielectric permittivity of SMG (16 wt%)/PVDF composite (83.8) at 1000 Hz was found to be ten-fold that of the corresponding value of pristine PVDF (8.3) with a relatively low dielectric loss factor (0.34) and a relatively high thermal conductivity (0.679 W/mK).

For the purpose of oil-water separation, the magnetic superhydrophobic melamine (MA) sponge was coated with the fluoroalkylsilane-modified Fe3O4 nanoparticles by a drop-coating method, in which the silicone adhesive was utilized to strengthen the binding effect between the Fe3O4 nanoparticles and the MA sponge. The successful preparation of fluoroalkylsilane-modified Fe3O4 nanoparticles and magnetic superhydrophobic MA sponge were confirmed by SEM, TEM, two dimensional EDS mapping, TGA, FTIR, XPS, WAXD, VSM, and contact angle measurement. The as-prepared surface-modified MA sponge could effectively absorb different oils including pump oil, peanut oil, silicone oil, kerosene, and gasoline with the maximum absorption capacities ranging from 59 g/g to 77 g/g. Moreover, it was demonstrated that the surface-modified MA sponge had an excellent ability to separate oil and organic solvent from water by direct absorption under magnetic control or gravity-driving filtration.

Water adsorption capacity is a key factor to influence the photocatalytic H2 evolution activity of polymeric g-C3 N4 . Herein, we report the synthesis of 3D ordered close-packed g-C3 N4 nanosphere arrays (CNAs) that significantly enhance the water adsorption capacity. Through precisely controlling the average stacking-layer number (ASLN) of the nanospheres in CNAs, we reveal an interesting stacking-layer-number dependence of water adsorption in the newly designed CNAs for accelerating the H2 evolution reaction, which can be attributed to the differences in adsorption surface areas and adsorption sites endowed by the point-defect cavities in sample CNAs.

The electrochemical reduction of carbon dioxide can convert the greenhouse gas into value-added chemical products or fuels, which provides a promising strategy to address current energy and environmental issues. Increasing the selectivity for C2&C2+ products, particularly ethylene, remains an important goal in this field. We chose cuprous chloride as the catalyst precursor for electrochemical reduction of CO2 , which efficiently converted carbon dioxide to ethylene. CuCl powder exhibited a maximum ethylene faradaic efficiency (FE) of 37%, ethylene partial current density of 14.8 mA/cm(2), and selectivity of 57.5% for C2&C2+ products at -1.06V (vs. reversible hydrogen electrode, RHE). Electron microcopy (TEM, SEM) and time-resolved ex situ X-ray diffraction (XRD) demonstrated that the catalyst was transformed gradually into a mixed phase of copper and cuprous oxide, with the morphological change into a cubic structure during reduction process. The presence of Cu1+ and the unique electrode morphology may simultaneously lead to the enhanced electrochemical activity. (C) 2018 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.

In this work, the fluoroalkylsilane-modified SiO2 nanoparticles (NPs) were immobilized on the polyurethane sponges by a highly efficient drop-coating method using different polymers including poly(vinylidene fluoride), poly(vinylidene fluoride-ter-trifluoroethylene-ter-chlorotrifluoroethylene), polystyrene, and polyurethane as the adhesives to achieve the superhydrophobic modification of the polyurethane sponges for oil-water separation. The successful fluoroalkylsilane modification for the SiO2 NPs was confirmed by TEM, SEM, FITR, XPS, and TGA. Furthermore, the surface-modified polyurethane sponges were investigated by SEM and two-dimensional EDS mapping. The contact angles of the surface-modified polyurethane sponges were in the range of 151.6°–154.3°, which confirmed the realization of the superhydrophobic modification for the polyurethane sponges. The demonstration experiments showed that the resulting surface-modified polyurethane sponge could effectively remove oil from the oil-water mixture by direct absorption or gravity-driven filtration. Moreover, the surface-modified polyurethane sponges possessed not only high absorption capability for different oils including peanut oil, pump oil, and silicone oil but also good reusability. We believe that such novel surface-modified polyurethane sponges might be potential candidates for the oil-water separation.