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Compressed hydrogen tanks are now widely used for onboard hydrogen storage in fuel cell vehicles (FCVs). However, because of the high storage pressure and the low thermal conductivity of carbon fibre reinforced polymer (CFRP), the emptying of such tanks during driving or emergency release can cause a significant temperature decrease and result in an in-tank gas temperature below the low safety temperature limit of −40 °C even in warm weather. Once the gas temperature within the tank is lower than −40 °C, the sealing elements at the boss of the tank may fail, and glass transition of the polymer liner of the type IV tank may occur; both can cause hydrogen leakage and severe safety problems. In this paper, the heat transfer correlations, thermodynamic analyses, computational fluid dynamics (CFD) simulations, experimental studies, and thermal management methods associated with the emptying process of compressed hydrogen tanks are comprehensively reviewed. Future research directions on this topic are suggested.

Analysis of the intermolecular vibrational modes in a fingerprint region is always difficult. It is particularly hard to figure out the normal modes, especially in the far-infrared (IR) region, whi...

Microporous polymer membranes hold great promise in carbon capture. However, engineering a continuous CO2-selective microporous network to achieve ultrahigh gas permeance and desirable selectivity remains a grand challenge. Aiming to manipulate the pore architecture and pore chemistry to implement efficient separation, knitted microporous polymer membranes are fabricated by in situ knitting composite membranes comprised of polyphenylene oxide (PPO) polymer and benzyl alcohol (BnOH). Specifically, the crosslinkers, formaldehyde dimethylacetal, bridge the neighboring aromatic backbones of PPO chains and BnOH to construct a highly crosslinked network with microporosity. By increasing the structural bridge density, the BET surface area of membranes increases from 4 to 538 m2 g−1. The formation of a highly interconnected microporous network provides remarkably increased permeability. Meanwhile, BnOH as a hydroxyl-containing functional building unit is knitted into micropore skeletons, which can directly tune the pore size and improve the CO2-philicity for enhanced selectivity. The resulting membrane displays an ultrahigh permeability of 4651.2 barrer with a CO2/CH4 selectivity of 27, and demonstrated good resistance to plasticization (up to 30 bar) and aging (for 190 days). This knitting strategy enabling versatile combination of building units with different structures and special functionalities may set up an innovative platform for fabricating a broad range of advanced membranes.

A vapor–liquid–solid horizontal circulating fluidized bed evaporation setup was constructed to study the thermal-exchange properties and pressure change. The influences of the operating variables, including the amount of added particles, heat flux, and circulating flow velocity, were systematically inspected using resistance temperature detectors and pressure sensors. The results showed that the heat transfer effect was improved with the increase in the amount of added particles, circulating flow velocity, and particle diameter, but decreased with increasing heat flux. The pressure drop fluctuated with the increase in operating parameters, except circulating flow velocity. The enhancing factor reached up to 71.5%. The enhancing factor initially increased and then decreased with the increase in the amount of added particles and circulating flow velocity, fluctuated with increasing particle diameter, and decreased with increasing heat flux. Phase diagrams showing the variation ranges of the operation variables for the enhancing factor were constructed.

A comprehensive design methodology is required to maximize the power capacity, the efficiency, and the power density of medium-frequency transformer (MFT), while complying with material, insulation, leakage inductance, and temperature limits. Different from the previous work, an analytical expression for the optimum conductor size of rectangular litz-wire conducting harmonic currents, which ensures best use of the available copper is proposed. A method to tune the leakage inductance with different winding configurations is presented. An insulation design scheme considering the influence of short-term power frequency sinusoidal wave and long-term square wave voltage excitations is put forward. Method to acquire the optimal dimension of fin array heat exchanger under forced air-cooling condition is presented. On this basis, the design methodology is established using the multiobjective nondominated sorting genetic algorithm II. A 1 kV, 200 kVA, 10 kHz nanocrystalline core MFT is designed and prototyped for a 10 kV, 2.5 MW solid-state transformer. The optimal design achieves an efficiency of 99.45%, a power density of 8 MW/m3, and a forced air-cooling temperature of 62 °C.

Flexible and wearable energy storage microdevice systems with high performance and safety are promising candidates for the electronics of on-chip integration. Herein, we demonstrate inkjet-printed ...

This paper carries out the transient behaviors of a thin rectangular plate considering different boundary conditions, Pasternak foundation, and thermal environment simultaneously. The governing differential equations of the system are derived by employing the Kirchhoff’s classical plate theory and Hamilton’s principle. This paper proposes a novel semi-analytical methodology, which integrates Laplace transform, the one-dimensional differential quadrature method, Fourier series expansion technique, and Laplace numerical inversion to analyze plates’ transient response. The proposed method can obtain dynamic response of the rectangular efficiently and accurately, which fills the gap of transient behaviors in semi-analytical method. A comparison between semi-analytical results and numerical solutions from the publication on this subject is presented to verify the method. Specifically, the results also agree well with the data generated by the Navier’s method. The convergence tests indicate that the semi-analytical algorithm is a quick convergence method. The effects of various variables, such as geometry, boundary conditions, temperature, and the coefficients of the Pasternak foundation, are further studied. The parametric studies show that geometry and temperature change are significant factors that affect the dynamic response of the plate.

The effect of evaporation section setting on the thermal performance of a closed thermosyphon combined with the fluidized bed heat transfer technology is experimentally investigated by varying the solid holdup (10–20%) and input power (50–300 W). Pure water and glass beads are chosen as the working media in a smooth copper tube. The results show that the particle addition may enhance the heat transfer of the thermosyphons under different evaporation section settings. The maximum reduction rate of the overall thermal resistance is 23.5% with a evaporation section length of 200 mm at solid holdup of 15% and input power of 300 W. The overall thermal resistances of the two-phase and three-phase thermosyphons decrease with the increase in evaporation section length. The upward movement of the evaporation section is beneficial to the heat transfer of the two-phase closed thermosyphon, but is not conducive to that of the three-phase closed thermosyphon.

An arcuate multi–orifice distributor is designed and fixed in the front shell cover of a horizontal liquid–solid circulating fluidized bed heat exchanger to inhibit the particle deposition in the front shell cover and improve the particle distribution in the tube bundle. Polyformaldehyde (POM) particles and water are selected as the working mediums. The influence of the inclination angle of the distributor (−34–42°) and the operating parameters such as the amount of added particles (0.5%–2.0%), circulation flow rate (7.9–19.9 m3/h), and particle diameter (3.15–5.5 mm) on the effect of the distributor is investigated by a charge–coupled device (CCD) system. The results show that the distributor can improve the particle distribution by 41%–90% at the optimal inclination angle of 27°, with a small increment in pressure drop. The findings are beneficial to the application of the fluidized bed heat transfer technology to the heat exchanger with horizontal tube bundle.

Thermal degradation of the composite constituted by high density polyethylene (HDPE) and microencapsulated red phosphorus (MRP) were studied using thermogravimetric (TG) data obtained at different heating rates. The kinetic models and parameters of the thermal degradation of MRP/HDPE composite were evaluated by FWO, KAS and IKP method. It indicates that the activation energy E of 4 % MRP/HDPE composite is higher than HDPE for three methods. MRP could improve the thermal stability and slow down the thermal degradation of HDPE. With adding MRP, the degradation mechanism of HDPE is changed and the degradation rate decreases.

Diamond particle with tungsten boride (WB) coating was synthesized by the molten salt method. Three different diamond/Fe-Ni composites made from pristine diamond, B4C coated diamond and WB coated diamond with Fe-Ni powders were prepared by powder metallurgy. The composition and microstructure of the tungsten boride coating were investigated. Both bending strength and cutting performance of the composites were investigated. Addition of the WB coating provided an increased bending strength (871.2 MPa) and relative density (93.54%), compared with the composites consist of uncoated diamond and Fe-Ni (746.8 MPa, 92.81%). Three different Fe-Ni-based impregnated diamond drill bits contained 20 vol.% pristine diamond, B4C coated diamond and WB coated diamond were manufactured by powder metallurgy, respectively. Drilling rate of bits was measured by XY-4 geological core drill on granite. The test results show that the drilling rate of bits with WB coated diamond (2.42 m/h) was 40% higher than that with pristine uncoated diamond (1.72 m/h).

A facile and eco-friendly way for fabrication of CuO is developed based on an one-step chemical precipitation route without calcination procedure or use of surfactant. The structure features of as-prepared CuO are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N2 adsorption-desorption experiment. X-ray diffraction analysis shows that CuO with particle size of 13.5–19.2 nm and crystallinity of 67.0–72.9% can be fabricated by the transformation of Cu(OH)2 precursor at bath temperature above 50 °C. By adjusting the oil bath temperature and the content of ammonium hydroxide, we demonstrate a formation mechanism to control CuO to be 2D leaf-like structure with large specific surface area of 33.4 m2/g and pore volume of 0.226 cm3/g, or 3D flower-like ones with specific surface area of 7.45–18.7 m2/g and pore volume of 0.0249–0.0850 cm3/g. The catalytic performances of as-prepared CuO are evaluated by monitoring degradation of methylene blue in the presence of hydrogen peroxide. Almost 100% methylene blue degradation rate can be reached after reaction for 210 min on 3D flower-like CuO synthesized with 10 mL ammonia content in oil bath of 50 °C. The high activity can be correlated with the morphology and pore volume of CuO. The present synthetic strategy is an inexpensive and convenient way suitable for large-scale fabrication of copper oxides, which are potential catalysts for organic compounds degradation.

Given the increasing concern regarding the global decline in rare earth reserves and the environmental burden from current wet-process recycling techniques, it is urgent to develop an efficient recycling technique for leftover sludge from the manufacturing process of neodymium–iron–boron (Nd–Fe–B) sintered magnets. In the present study, centerless grinding sludge from the Nd–Fe–B sintered magnet machining process was selected as the starting material. The sludge was subjected to a reduction–diffusion (RD) process in order to synthesize recycled neodymium magnet (Nd2Fe14B) powder; during this process, most of the valuable elements, including neodymium (Nd), praseodymium (Pr), gadolinium (Gd), dysprosium (Dy), holmium (Ho), and cobalt (Co), were recovered simultaneously. Calcium chloride (CaCl2) powder with a lower melting point was introduced into the RD process to reduce recycling cost and improve recycling efficiency. The mechanism of the reactions was investigated systematically by adjusting the reaction temperature and calcium/sludge weight ratio. It was found that single-phase Nd2Fe14B particles with good crystallinity were obtained when the calcium weight ratio (calcium/sludge) and reaction temperature were 40 wt% and 1050 °C, respectively. The recovered Nd2Fe14B particles were blended with 37.7 wt% Nd4Fe14B powder to fabricate Nd–Fe–B sintered magnets with a remanence of 12.1 kG (1 G = 1 × 10−4 T), and a coercivity of 14.6 kOe (1 Oe = 79.6 A·m−1), resulting in an energy product of 34.5 MGOe. This recycling route promises a great advantage in recycling efficiency as well as in cost. Keywords: Nd–Fe–B grinding sludge, Recycled sintered magnets, Calcium reduction–diffusion, Rare-earth-rich alloy doping

For liquid water in the far-infrared spectrum, phonons of molecular vibrations constitute two bands with a narrow gap at around 30 meV. Interestingly, there are two distinct peaks for ice in this g...

The coercivity, microstructure, and magnetic domain structure of Nd–Fe–B sintered magnets by grain boundary diffusion process (GBDP) with TbH3 nanoparticles were systematically investigated. Compared to the original magnet, the coercivity (Hci) of the GBDP magnets improved from 1702 to 2374 kA·m−1 with few remanence reduced from 1.338 to 1.281 T. Electron probe micro-analysis (EPMA) analysis showed that Tb diffused along grain boundary, mainly concentrated in the boundary layer of the main phase, and formed a core–shell structure. Magneto-optical Kerr optical microscope (MOKE) analysis showed that there were two types of magnetic domain reversal in one grain: gradual reversal (GR) and abrupt reversal (AR). When the applied field decreased from saturated magnetic field, the reversal magnetic domain nucleated and then spread over the whole grain gradually, which was called GR. However, some grains kept the single domain state until Hh which was a value of reverse direction applied field in second quadrant in hysteresis loops. When the applied field increased above Hh, reversed magnetic domain would suddenly appear and occupy most of the area of the grain, which was called AR. That is because AR grains have higher reversed magnetic domain nucleation field (HRN2) than GR grains (HRN1). After GBDP, the area of AR region increased obviously and GR region decreased accordingly, indicating that the core–shell structure could change GR grain into AR grain. The core–shell structure could suppress flipping of the magnetization of the grains due to the large magnetic anisotropy of Tb-rich shell. Therefore, large AR area led to high coercivity.

The hydrogen-disordered structure of ice, Ic, makes it difficult to analyze the vibrational normal modes in the far-infrared region (i.e., the molecular translation band). To clarify the origin of the energy-splitting of hydrogen bond vibrations in this area, a 64-molecule supercell was constructed and calculated using first-principles density functional theory. The results were in good agreement with inelastic neutron scattering experiments and our previous study of a hydrogen-ordered ice Ic model. Assisted by analytic equations, we concluded that the origin of the two hydrogen bond peaks in real ice Ic is consistent with that of hydrogen-ordered ice Ic: the peaks originate from two kinds of normal mode vibration. We categorize the four peaks in the far-infrared region recorded from inelastic neutron scattering experiments as the acoustic peak, the superposition peak, the two-hydrogen bond peak and the four-hydrogen bond peak. We conclude that the existence of two intrinsic hydrogen bond vibration modes represents a general rule among the ice family, except ice X.

In this study, an experimental device is designed and built to investigate the heat transfer characteristics in a downflow circulating fluidized bed evaporator. The tested downer has a length of 1200 mm and a dimension of Ф38 mm × 3 mm. Polyformaldehyde (POM), SiC and glass bead particles are used as the inert solid particles. A range of experimental investigations are performed by varying the amount of added particles (0.5–2.0%), heat flux (8–16 kW·m−2) and circulation flow velocity (0.56–1.78 m/s). Results show that as the addition of the particles destroys the laminar sublayer and increases nucleate sites, the boiling heat transfer coefficient of the three-phase flow is higher than that of the two-phase flow. All three kinds of particles added can enhance the heat transfer. The maximum enhancing factors are 78.5%, 68.8%, and 72.1% within the range of experiments for POM, glass bead and SiC particles, respectively. The flow boiling heat transfer coefficient initially increases and then decreases or fluctuates with the increase in the amount of added particles. The circulation flow velocity has two aspects of influence on the flow boiling heat transfer. The enhancing factor increases with the increase in circulation flow velocity at low heat flux, but initially increases and then decreases at high heat flux. The enhancing factor decreases with the increase in heat flux because of the generation of vapor film on the heating wall. Three dimensional diagrams are established to determine the optimum particles. The results can provide some references for the industrial application of the circulating fluidized bed heat transfer technology.

According to a report, the existence of two characteristic hydrogen bond (H-bond) peaks in the translational band of ice does not occur in high-pressure ice VIII. To test this, a comparative analys...

In this paper, a direct co-precipitation method was used to prepare antimony-doped calcium fluoride nanopowders (NPs). The effects of reaction concentration, reaction medium and lanthanum doping on the properties of calcium fluoride NPs were investigatedviaa control variable method and the best preparation conditions was identified. The structural analysis of the powder materials prepared in this work were carried out by XRD, SEM, ICP and other test methods. By analyzing the experimental data, we found that the best performance of Eu-doped CaF2NPs can be acquired under the reaction concentration of 1 mol/L in aqueous solution. In the same time, the NPs possess a high degree of dispersion with an average diameter of 22 nm, which is beneficial to the preparation of transparent Eu3+: CaF2ceramics with excellent up-conversion luminescence. The results show that the grain size, the crystallinity of the NPs and the amount of Eu infiltration have a decreasing tendency with the increasing reaction concentration, while the degree of agglomeration of the NPs can be enhanced by increasing the reaction concentration.

Surface-controlled CuOx/rGO nanocomposite has been successfully fabricated in this study using a simple hydrothermal method. In addition to the characterization by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2 adsorption/desorption, the catalytic conversions of 4-nitrophenol (4-NP), methylene blue (MB) or rhodamine B by the CuOx/rGO nanocomposite in the presence of NaBH4 were carried out. The results demonstrate that all the selected probe reactants show no adsorption on the as-prepared CuOx/rGO nanocomposite, however, their conversions are close to 100% and can be carried out within several minutes. The excellent catalytic activities may be associated with the multi-valenced copper species and the controlled surface of the CuOx/rGO nanocomposite. In the meantime, the CuOx/rGO nanocomposite has a better stability and can be reused for many times without obvious decrease in activity, suggesting a great potential of the as-prepared CuOx/rGO nanocomposite for catalytic degradation of organic pollutants.

The counter-gravity casting methods have been developed to remove the casting defects of Mg based alloys. However, the effects of different counter-gravity casting methods on the microstructure and mechanical properties have not been studied in detail. ZM5 alloys were prepared by gravity casting, low-pressure casting and counter-pressure casting, respectively. The mechanical properties, microstructure and fracture morphologies were examined and compared by means of optical microscopy, scanning electron microscopy methods and tensile testing. Results show that casting defects such as gas pore, shrinkage porosity and cavity can be eliminated by counter-pressure casting. The grain size of α-Mg is decreased signifi cantly by counterpressure casting. Moreover, the precipitated particles are more uniform and fi ner in the counter-pressure casting sample. As a result, the mechanical properties of the alloys are greatly improved. The tensile strength and elongation of the samples by counter-pressure casting are 285 MPa and 13.9%, respectively, which are much higher than those of the low pressure casting and gravity casting.

Summary Interfacial polymerization (IP) is a platform technology for ultrathin membranes. However, most efforts in regulating the IP process have been focused on short-range H-bond interaction, often leading to low-permselective membranes. Herein, we report an electrostatic-modulated interfacial polymerization (eIP) via supercharged phosphate-rich substrates toward ultra-permselective polyamide membranes. Phytate, a natural strongly charged organophosphate, confers high-density long-range electrostatic attraction to aqueous monomers and affords tunable charge density by flexible metal-organophosphate coordination. The electrostatic attraction spatially enriches amine monomers and temporally decelerates their diffusion into organic phase to be polymerized with acyl chloride monomers, triggering membrane sealing and inhibiting membrane growth, thus generating polyamide membranes with reduced thickness and enhanced cross-linking. The optimized nearly 10-nm-thick and highly cross-linked polyamide membrane displays superior water permeance and ionic selectivity. This eIP approach is applicable to the majority of conventional IP processes and can be extended to fabricate a variety of advanced membranes from polymers, supermolecules, and organic framework materials., Graphical abstract, Highlights • Electrostatic-modulated interfacial polymerization is proposed for the first time • Electrostatic attraction regulates the spatial-temporal distribution of amine monomers • Monomer regulation leads to reduced thickness and enhanced cross-linking of membrane • Ultrathin and highly cross-linked polyamide membrane displays superior permselectivity, Supramolecular Materials; Materials Science; Materials Chemistry; Materials Synthesis; Polymers

The growth in aerosol particles caused by water uptake during increasing ambient relative humidity alters the physical and chemical properties of aerosols, which then affects public health, atmospheric chemistry, and the Earth’s climate. The temporal resolution and sensitivity of current techniques are not sufficient to measure the growth dynamics of single aerosol nanoparticles. Additionally, the specific time required for phase transition from solid to aqueous has not been measured. Here, we describe a label-free photonic microscope that uses the Bloch surface waves as the illumination source for imaging and sensing to provide real-time measurements of the hygroscopic growth dynamics of a single aerosol (diameter

Efficient olefin/paraffin separation is a grand challenge because of their similar molecular sizes and physical properties, and is also a priority in the modern chemical industry. Membrane separation technology has been demonstrated as a promising technology owing to its low energy consumption, mild operation conditions, tunability of membrane materials, as well as the integration of physical and chemical mechanisms. In this work, inspired by the physical mechanism of mass transport in channel proteins and the chemical mechanism of mass transport in carrier proteins, recent progress in channel‐based and carrier‐based membranes toward olefin/paraffin separations is summarized. Further, channel‐based membranes are categorized into membranes with network structures and with framework structures according to the morphology of channels. The separation mechanisms, separation performance, and membrane stability in channel‐based and carrier‐based membranes are elaborated. Future perspectives toward membrane‐based olefin/paraffin separation are proposed., Recent progress in channel‐based and carrier‐based membranes toward olefin/paraffin separations is summarized. Further, channel‐based membranes are categorized into membranes with network structures and with framework structures according to the morphology of channels. The separation mechanisms, separation performance, and membrane stability in channel‐based and carrier‐based membranes are elaborated. Future perspectives toward membrane‐based olefin/paraffin separation are proposed.

We report on the design and implementation of an integrated dual-color stimulated emission depletion (STED) microscopy and fluorescence emission difference (FED) microscopy. This highly integrated system combines the respective advantages of STED and FED microscopies, enabling acquisition of super-resolution STED images with specific fluorophores and high laser power, or resolution-enhanced FED imaging for ordinary fluorescent dyes and other materials with moderate demand for laser power. The functional integration enables researchers to select the more appropriate microscopy according to practical scenario and requirements, giving full play to their respective strengths and satisfying the imaging demands maximally. The system’s resolution is characterized by dual-color imaging of fluorescent particles. Its practical applicability is verified through imaging various kinds of samples, including several fixed cells stained with different organic dyes and a given organic material—organometallic halide perovskite.

In this work, an Au-Ag alloy nanourchin (Au-Ag alloy NU) based electrochemiluminescent (ECL) sensor for the measurement of cardiac troponin I (cTnI) was developed. The as-prepared Au-Ag alloy NUs exhibited higher specific surface area and better conductivity owing to their unique urchin-like morphology, which resulted in excellent electrocatalytic activity towards H2O2 in the luminol-H2O2 ECL system. We have found that the Au-Ag alloy NUs could enhance the ECL signal in the luminol-H2O2 solution. Based on these facts, a facile and label-free ECL immunosensor has been constructed for the analysis of cTnI, a cardiac biomarker, with a wide linear range of 3.5 pg mL-1-350 μg mL-1. This novel ECL immunosensor has good stability and reproducibility, showing potential application in clinical diagnostics. In addition, a non-enzymatic electrochemical sensor for H2O2 was also fabricated, with a wide linear detection range of 100 nM-200 μM, a low limit of detection of 45 nM and a fast response time (less than 2 s).

Conjugate heat transfer of air and steam in a rectangular channel with 90° ribs along two opposite walls was investigated experimentally and numerically. The stainless steel test section was 80 mm × 40 mm × 2.5 mm and the ribs were 80 mm × 2.5 mm × 2.5 mm with 25 mm between ribs. The tests investigated the effects of coolant mass flow rate (the corresponding Reynolds numbers in the range of 10,000-50,000) on the conjugate heat transfer enhancement with the ribs. Two conjugate heat transfer calculation methods with different models were developed. For the first model (CHT-Q model) solid domain was viewed as a uniform internal heat source with the adiabatic exterior surfaces, while for the second model (CHT-T model) the outwall temperature was specified by the fitting polynomials of measured data with the zero internal heat. Comparisons between the experimental and numerical results showed that the SST k–ω turbulence model was more suitable for the conjugate heat transfer in such channels. Regardless of numerical error, an approximation of heat loss was specified by the successive trial calculations of the CHT-Q model, while a relatively accurate heat loss was evaluated by the post-processing of the CHT-T calculation. Local heat transfer coefficient can be determined accurately by the quantified heat loss of test system. The critical impact of conjugate heat transfer was demonstrated. Furthermore, the steam coolant compared to air exhibited a higher heat transfer performance by 12–25% for both the ribbed and smooth walls at the same Reynolds number.

Flexible power packs combining a flexible photovoltaic part with a wearable all-solid-state supercapacitor as the self-sustaining energy system to power wearable device have attracted great interest due to the increasing demands for green energy and the tendency for multi-functionalization in electronics industry. To meet this energy requirement, we report an asymmetric all-solid-state supercapacitor, then integrate with commercial flexible solar cells to develop a self-sustaining power pack. In view of comfort for wearable electronics, cotton-textile radiation-proof clothes commonly used for pregnant woman cloth (PWC) are selected as the flexible substrate to construct wearable energy storage devices, which have the properties of flexible, green, renewable, breathable and excellent conductivity. Experimental tests demonstrate that the wearable asymmetric supercapacitors with high power density and relatively large energy density, fast charge/discharge capability, light-weight, excellent reliability and flexibility can enable the solar energy captured from the environment to afford a continuous and stable output of electric power and diminish the solar energy fluctuations. The supercapacitor is assembled with the Co–Ni layered double hydroxides (Co-Ni LDH) nanosheets as the positive electrode and the FeOOH as the negative electrode. Furthermore, the fabricated self-sustaining power pack as the energy source can continuously power the press sensor for monitoring the human physiological signals regardless of the sunlight fluctuation, demonstrating its potential usage in future wearable and portable electronic devices.

We propose a novel parallelized fluorescence lifetime imaging microscopy (FLIM) method based on photon reassignment with a detector array and time-correlated single photon counting (TCSPC) array. The detector array composed of seven avalanche photon diodes (APDs) substitutes for original pinhole and detector to constitute an imaging scanning microscopy (ISM) system. The introduction of parallel detection can solve the pile-up effect caused by the dead-time in TCSPC measurement, which can enhance the effective photon detection efficiency and notably increase the fluorescence lifetime imaging speed. More importantly, the resolution and signal–noise ratio (SNR) can be enhanced based on photon reassignment. The simulation results embody the superiority of our FLIM system, and the experiments with different samples validate the improvement of the resolution and speed of fluorescence lifetime imaging. The experiment results show that the resolution of our method is enhanced by a factor of 1.5 and the imaging speed can be at least increased by a factor of 2.5 compared with conventional confocal TCSPC FLIM system. We envision that the proposed FLIM method based on parallel detection will allow for super-resolution fluorescence lifetime real-time imaging of live cell.

Recently, interest in the use of carbonaceous materials derived from sustainable biomass wastes for supercapacitors (SCs) has grown. The sustainable sunflower stalk is selected as the raw material for preparing activated carbon (AC), using a simple hydrothermal carbonization (HTC) combining an effective activation method. The as-prepared AC sample possesses a unique mesoporous layer-stacking structure which has an unexpected surface area up to 1505 m2 g–1 as well as a pore size of 3.6 nm on average. As an electrode material for SCs, the AC demonstrates high electrochemical storage capacity, with the excellent capacitances of 365 and 263 F g–1 measured by three-electrode and symmetrical SCs systems, respectively. An outstanding capacitance retention rate and a good stability value maintained after 15 000 cycles are close to 81 and 95%, respectively, which are obtained at a current density of 20 A g–1. Further, the symmetrical SCs exhibits an energy density as high as 35.7 Wh kg–1 under the condition of a p...

Nowadays, intelligent piezoelectric materials are widely used in transducer devices and aerospace structures. To investigate the dynamic behaviour of a functionally graded piezoelectric material (FGPM) cylindrical panel, a semi-analytical approach by introducing the Laplace transform, differential quadrature method, state space approach and Durbin’s numerical inversion of Laplace transform is presented. The accuracy of this method is validated by comparing the results with the published literature and by ANSYS under various boundary conditions. Convergence studies showed the proposed approach has a quick convergence rate with growing sample point numbers and increasing layer numbers. The analysis of initial electric potential on the outer surface and bottom surface indicated that when the plus and minus signs of two sides are opposite, the value of central electric potential will decrease. Under simply supported condition, if FG index γ increases, the deflection amplitude of the panel will increase, while the electric potential amplitude decreases. Moreover, the amplitude of displacements along the radial direction becomes larger when the central angle increases, but the period time decreases at the same time. The proposed method fills a gap of 3-D semi-analytical investigations for the dynamic behaviour of FGPM cylindrical panels in different boundary conditions.

Recently, recycling of severely contaminated Nd–Fe–B sintered magnets sludge had drawn considerable attention due to the concern of environmental burden and high cost of traditional wet process rec...

The exploration of energy conversion and storage devices for wide-temperature operation is presently a grand challenge. Herein, the single-crystalline integrated energy-storage units based on highly-oriented 4H-SiC nanochannel arrays (NCAs) were fabricated via an improved electrochemical anodic oxidation technique from 4H-SiC wafers. The as-prepared SiC NCAs electrode exhibits an areal capacitance of 14.8 mF cm−2 at 10 mV s−1, which is the highest for SiC electrodes ever reported and also 6-fold higher in comparison to that of SiC nanowire array electrode (NWAs, 2.32 mF cm−2). Moreover, the resultant 4H-SiC NCAs exhibit an extremely stable cycling performance in aqueous electrolytes, with higher than 95% retention of initial capacitance regardless of being serviced under low, high or cross-fade temperatures for 11 000 charge–discharge cycles, demonstrating that they are nearly full-featured for robust wide-temperature operation.

Reduced graphene oxide (Ni/rGO) decorated by metallic Ni nanoparticles (NPs) was firstly fabricated through in situ thermal decomposition and subsequent reduction in 5% H2/N2 gas at 600 °C, and then Au NPs were loaded on the surface of the as-prepared Ni/rGO. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM) were used to characterize the Ni-decorated rGO and Ni/rGO@Au nanocomposites. The results show that both Ni and Au NPs are highly dispersed on rGO, and Ni/rGO@Au possesses excellent activity toward the conversion of 4-nitrophenol into 4-aminophenol in the presence of NaBH4, showing almost four orders of magnitude higher activity parameter κ (9.7 × 10−2 s−1mg−1) than Ni/rGO (1.1 × 10−5 s−1mg−1), though Ni/rGO has a better performance in the catalytic conversion of 4-NP. In the meantime, the Ni/rGO@Au can be easily recycled by an external magnetic field and the conversion of 4-nitrophenol at the 8th cycle is still close to 95%.

Flexoelectricity becomes remarkable in nanoscale dielectrics where strong strain gradients are expected. The effect of flexoelectricity on elastic plane waves propagating in nanoscale layered phononic crystals is discussed in the current work. The fundamental governing equations and boundary conditions are derived from the virtual work principle. Detailed calculations are performed for nanoscale two-layered and three-layered phononic crystals using the transfer matrix method. Numerical results indicate that phononic crystals possess frequency pass bands and stop bands. For nanoscale layered phononic crystals, flexoelectricity increases the middle frequency regardless of the thickness ratio, whereas the flexoelectric effect on the bandwidth depends on the thickness ratio, which implies that there is an optimal thickness ratio to maximize the bandwidth. In addition, the middle frequency and bandwidth decrease with an increase in the unit cell thickness if the thickness ratio is fixed. Hence, considering the flexoelectric effect on band structures of nanoscale phononic crystals may provide guidance in manipulating elastic wave propagation and facilitate potential applications in phononic crystal devices.

High-performance conjugated microporous polymer (CMP)/TiO2 photocatalytic antibacterial nanocomposites were successfully synthesized by in situ Sonogashira polymerization. TiO2 was uniformly dispersed onto the surface and within the CMP which show the microporous nature with narrow pore size distribution. The high crystallinity and thermal stability of the CMP/TiO2 nanocomposites are attractive for use as antibacterial materials. The composites we prepared showed excellent photocatalytic antibacterial properties for the inactivation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under visible light irradiation. The photocatalytic antibacterial rates of nanocomposites against E. coli and S. aureus after 120 min of visible light irradiation were 98.14% and 100%, respectively. The superoxide anion ( O2−) was confirmed to be an important substance in the antibacterial process above. The cytocompatibility of the antibacterial agents was studied in terms of cytotoxicity against NIH 3T3 fibroblasts. More than 95% of the cells were still alive in the presence of the nanocomposites, both without and with light irradiation, indicating the good cytocompatibility of the nanocomposites. Judging from the excellent photocatalytic antibacterial properties and ultralow toxicity of nanocomposites, these materials can be used in many fields such as medical treatment, transportation and construction.

It was reported that a scanning tunneling microscopy (STM) study observed the adsorption geometry of a water monomer and a tetramer on NaCl(100) film. Based on first-principles density functional theory (DFT), the adsorption behavior of water on the NaCl surface was simulated with CASTEP code. The results showed that the water monomer almost lay on the NaCl(001) surface with one O–H bond tilted slightly downward. This was quite different from the STM observations. In fact, the experimental observation was influenced by the Au(111) substrate, which showed an upright form. A recent report on observations of two-dimensional ice structure on Au(111) substrate verified our simulations. However, the water tetramer formed a stable quadrate structure on the surface, which was consistent with observation. The intermolecular hydrogen bonds present more strength than surface adsorption. The simulations presented a clearer picture than experimental observations.

Superhydrophobic conjugated microporous polymer-coated sponges (CMP@sponges) have been synthesized by the in-situ Sonogashira polymerization of monomers with multiple carboxyl or hydroxy functional groups in the presence of melamine sponges in a one-pot synthesis. The water contact angles of CMP@sponges are 150.38 and 153.92°, respectively. Unsupported CMP nanowires with diameters of 50–150 nm are synthesized successfully. CMP@sponges show excellent separation efficiency not only for oil/water mixtures including low-density oils that float and high-density oils that sink (such as gasoline, diesel and common organic solvents) but also for emulsified oils, which are much more difficult to separate with high efficiency (up to 99.81% for a toluene-water emulsion). The absorption capacities of CMP@sponges for oils are exceptionally high (55–122 and 38–94 g/g) and stable after 10 cycles. Judging from the excellent performance of CMP@sponges on oil/water separation, an ultrafast oil-removal setup has been designed that can be used to continuously collect floating oil at high speed and with a high separation efficiency (up to 10.2–16.3 mL/s). In addition, the recovery of palladium ions (Pd(II)) from organic palladium waste solutions by using CMP@sponges has been achieved, and 297 mg/g Pd(II) ions can be adsorbed. This is the first example of a CMP@sponges setup, which can continuously recover oils from oil/water mixtures with high efficiency and can also be used for recovering Pd(II) from organic solvents. The novel CMP@sponges show great application prospects for treating oil spills and heavy metal pollution.

There is increasing concern that the locally resonant phononic crystals (LRPCs) are used to reduce low-frequency noise and vibration in ship and ocean engineering. In this work, the vertical velocity amplitude spectrums in “ChangJing 9″ are measured following the ISO international standards. According to the low-frequency mechanical vibration generated by the power systems on the ship, a single-phase spiral-shaped phononic crystal is designed and analyzed based on the locally resonant modes. The vibration characteristics of the phononic crystal plates with different boundary conditions and loads are numerically simulated, and groups of experimental tests are conducted to verify the abilities of vibration isolation for three kinds of phononic crystals. Furthermore, a vibration isolation platform installed on a steel plate is also studied by numerical simulations and experiments. The results show that the spiral phononic crystal has good adaptability for a wide range of low-frequency band, around 15–45 Hz, by altering the cylinders conveniently. The LRPC has a potential application to isolate vibration for protecting electronic devices and precision instruments despite the complex vibration sources and boundaries on the ship. In short, this work is an active exploration of putting the LRPCs into the field of ship vibration and noise control.

In this paper, the flexoelectric effect on Love waves propagating in a structure with a nanoscale piezoelectric guiding layer deposited on an isotropic elastic substrate is analytically investigated. Transcendental complex dispersion equations are obtained and solved numerically which are corresponding to the electrically open and short conditions at the free surface. A detailed discussion about the dispersion relations of the fundamental mode is subsequently presented. The results indicate that flexoelectricity has a substantial effect on Love wave propagation. The presence of flexoelectricity leads to a complex phase velocity with a negative/positive imaginary part, which means Love waves attenuate/grow over time. In addition, the phase velocity dispersion relations depend greatly on the thickness and flexoelectric coefficients of the guiding layer. The current work is the first attempt to explore the flexoelectric effect on the propagation characteristics of surface acoustic waves (SAWs). And t...

The biomedical co-continuous (β-TCP+MgO)/Zn-Mg composite was fabricated by infiltrating Zn-Mg alloy into porous β-TCP+MgO using suction exsorption technique. The microstructure, mechanical properties and corrosion behaviors of the composite were evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical testing, electrochemical and immersion test. It was found that the molten Zn-Mg alloy had infiltrated not only into the pores but also into the struts of the porous β-TCP+MgO scaffold to form a compact composite. The Zn-Mg alloy contacted to the β-TCP+MgO scaffold closely, and no reaction layer can be found between the alloy and the scaffold. The compressive strength of the composite was as high as 244 MPa, which was about 1000 times higher than that of the original porous β-TCP+MgO scaffold and 2/3 of the strength of the Zn-Mg bulk alloy. The electrochemical and immersion tests in simulated body fluid (SBF) solution indicated that the corrosion resistance of the composite was better than that of the Zn-Mg bulk alloy. The corrosion products on the composite surface were mainly Zn(OH) 2 . Appropriate mechanical and corrosion properties indicated that the (β-TCP+MgO)/Zn-Mg composite fabricated by suction exsorption would be a very promising candidate for bone substitute.

Substrate, a typical ultra-slender aluminum alloy structural components with a large aspect ratio and complex internal structure, was traditionally manufactured by re-assembly and sub-welding. In order to realize the monoblock casting of the substrate, the Pro/E software was utilized to carry out three-dimensional (3D) modeling of the substrate casting, and the filling and solidification processes were calculated, as well as the location and types of casting defects were predicted by the casting simulation software Anycasting. Results of the filling process simulation show that the metal liquid is distributed into each gap runner evenly and smoothly. There is no serious vortex phenomenon in the mold cavity, and the trajectory of the virtual particles is clear. Results of the solidification process simulation show that shrinkage cavities mainly appear at the junction of gap runners and the rail surface of the substrate. The average deformation is 0.6 mm in X direction, 3.8 mm in Y direction, and 8.2 mm in Z direction. Based on the simulation results, the casting process of the substrate was optimized, and qualified castings were successfully produced, which will provide a reference for the casting process design of other ultra-slender aluminum alloy structural components.

The uniform monodispersed vanadium-doped three-dimensional dendritic mesoporous silica nanospheres (nV-MSNSs) were successfully synthesized in a heterogeneous oil–water biphase stratification reaction system and characterized by several state-of-the-art methods. The synthesized nV-MSNSs were applied to the oxidative dehydrogenation of the propane (ODHP) reaction with the presence of CO2 and exhibited excellent catalytic performances. The results show that the vanadium loading (1.3–8.0 wt %) evidently influences the textural properties, oxidation state, and polymerization degree of vanadium species of nV-MSNSs. The specific surface area (SBET), pore diameter (Dp), and pore volume (Vp) of nV-MSNSs decrease with the loading of vanadium species. The excessively high vanadium loading leads to the slight connection of nanospheres, but does not affect the assembly and growth of the three-dimensional (3D) dendritic channels. The percentage of highly dispersed vanadium VV species gradually increases and attains th...

Transition metal coordinated porphyins generally exhibit effective carbon-chloride bond cleavage of environmentally harmful organochlorides through electrochemical reductive catalysis in non-aquaous media, but the recyclable use of the catalyst remains a challenge. In this manuscirpt, a new strategy of an efficient and recyclable C−Cl bond cleavage is described, and the structural characterization, electrochemical behaviour and electrochemical catalysis were illustrated by various techniques. It is demonstrated that the Fe3O4@SiO2@Co(II)porphyrin magnetic materials can be effectively used for at least 30 cycles.

Different from piezoelectricity which is restricted to certain materials, flexoelectricity is a universal electromechanical coupling in all dielectrics. In this work, mechanical energy harvester models were developed based on Timoshenko laminated beam theory, in which the flexoelectric and piezoelectric mechanisms were discussed. For a three-layered energy harvester in parallel configuration, the mechanical vibration energy can be converted into electrical energy due to flexoelectricity, and for the three-layered energy harvester in series configuration, the energy conversion is enhanced by the flexoelectricity. Resonance frequency shifts were observed in the calculations due to flexoelectricity and external circuit resistance. It is found that the electromechanical coupling displayed from the electrical responses versus resonance frequency and resistance. The energy conversion for the three-layered energy harvester system was found to be increased with the decrease in the laminated beam thickness. The energy conversion calculated for different numbers of layers also indicates that laminated energy harvester systems excel single-layered energy harvesters. This work therefore might help in designing flexoelectricity-based energy harvesters.

Imaging and tracking three-dimensional (3D) nanoscale organizations and functions of live cells is essential for biological research but it remains challenging. Among different 3D super-resolution techniques, 3D structured illumination microscopy (SIM) has the intrinsic advantages for live-cell studies; it is based on wide-field imaging and does not require high light intensities or special fluorescent dyes to double 3D resolution. However, the 3D SIM system has developed relatively slowly, especially in live imaging. Here, we report a more flexible 3D SIM system based on two galvanometer sets conveniently controlling the structured illumination pattern's period and orientation, which is able to study dynamics of live whole cells with high speed. We demonstrate our microscope's capabilities with strong optical sectioning and lateral, axial, and volume temporal resolution of 104 nm, 320 nm and 4 s, respectively. We do this by imaging nanoparticle and microtubule organizations and mitochondria evolution. These characteristics enable our galvanometer-based 3D SIM system to broaden the accessible imaging content of SIM-family microscopes and further facilitate their applications in life sciences.

Natural gas hydrates are ice-like crystalline materials formed from natural gas and clathrate ice under high pressure and low temperature. Ice XVI, the first S-II type clathrate ice produced in the lab, was simulated by first-principles density functional theory with the CASTEP code. A 34-molecule supercell was built to mimic the hydrogen-disordered structure. The vibrational spectra were calculated as a reference for inelastic neutron scattering (INS), infrared (IR) absorption, and Raman scattering experiments. Two kinds of H-bond vibration modes corresponding to two different bond strengths were found in our previous studies. In this paper, the statistics of distribution calculated by integrating these two kinds of modes was found to match the phonon density of states (PDOS) very well. We confirmed that the two basic types of H-bonds also appeared in clathrate ice XVI. The typical normal modes were analyzed to illustrate the dynamic process of lattice vibrations.

An analytical method and a semi-analytical method are proposed to analyze the dynamic thermo-elastic behavior of structures resting on a Pasternak foundation. The analytical method employs a finite Fourier integral transform and its inversion, as well as a Laplace transform and its numerical inversion. The semi-analytical method employs the state space method, the differential quadrature method (DQM), and the numerical inversion of the Laplace transform. To demonstrate the two methods, a simply supported Euler–Bernoulli beam of variable length is considered. The governing equations of the beam are derived using Hamilton's principle. A comparison between the results of analytical method and the results of semi-analytical method is carried out, and it is shown that the results of the two methods generally agree with each other, sometimes almost perfectly. A comparison of natural frequencies between the semi-analytical method and the experimental data from relevant literature shows good agreements between the two kinds of results, and the semi-analytical method is validated. Different numbers of sampling points along the axial direction are used to carry out convergence study. It is found that the semi-analytical method converges rapidly. The effects of different beam lengths and heights, thermal stress, and the spring and shear coefficients of the Pasternak medium are also investigated. The results obtained in this paper can serve as benchmark in further research.

A typical vibrational spectrum in the ice phase has four separate bands: Translation, libration, bending, and stretching. Ice X, the final ice phase under high pressure, shows an exotic vibrational spectrum. Based on harmonic approximation, an ideal crystal of ice X has one peak, at 998 cm&minus, 1, for Raman scattering and two peaks, at 450 cm&minus, 1 and 1507 cm&minus, 1, for infrared absorption in this work. These three characteristic peaks are indicators of the phase transition between ice VII and VIII and ice X. Despite many experimental and theoretical works on ice X, only this study has clearly indicated these characteristic peaks in the region of the IR band. The phonon density of states shows quite different features than ice VIII, which could be verified by inelastic neutron scattering in the future. The dynamic processes of 15 vibrational normal modes are discussed and the typical hydrogen bonds are missing.

A series of five C2 Symmetric A2B2 type borneol-porphyrin hybrids have been synthesized and characterized. Moreover, a detailed analysis of their optical and redox properties was carried out by comparing the results obtained via optical spectroscopy and electrochemistry. The current results demonstrated that the meso borneol-substitutions excitation coupled strongly with porphyrin core that leads to significant CD signals in the Soret band region, and molecular anti-cancer behaviors were also investigated.