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Corrosion tests of 316 stainless steel (316SS) in NaCl–KCl–NaF reciprocal salts were conducted at different temperatures. Results showed that the reciprocal salts had perfect compatibility with 316SS even without special treatment, and a stable Cr–O enriched layer was first observed. The stabilization mechanism of chromium oxides in molten salts was explored, where the low oxoacidity was conducive to from the stable chromium oxides. These findings can provide a new direction for the design and corrosion control of molten salts. • Corrosion behavior of 316SS in NaCl-KCl-NaF salts was studied at high temperature. • NaCl-KCl-NaF salts had perfect compatibility with 316SS without special treatment. • Corrosion zone of three-layer structure and stable protective layer were observed. • Stabilization mechanism of Cr oxides protective layer in molten salts was explored. [ABSTRACT FROM AUTHOR]

The extreme chemical inertness of high-modulus carbon fiber (HMCF) makes its functionalization quite difficult. In this work, a new method was explored to grafted glycidyl methacrylate (GMA) onto the surface of HMCF combined acid activation with co-radiation grafting. Structural changes and surface morphologies were investigated in detail. GMA was successfully grafted on to HMCF after acid activation synergized with ionization radiation, and the grafting degree was calculated to be 22%. The O/C atom ratio, content of the oxygen-containing functional groups on the surface. After acid activation and grafting, the hydrophilicity is effectively improved, and it can be wetted by water with good dispersibility in water. The surface structure of the fiber became highly disordered after grafting GMA. Finally, the grafting mechanism was discussed. The carboxyl groups introduced by the acid activation should be responsible for the successful grafting of the HMCF. This work provides a new pathway to fulfill the modification of HMCF and will be beneficial for obtaining high performance HMCF composites. [Display omitted] • Hydrophilicity of HMCF was efficiently enhanced after acid activation and grafting. • The surface structure of the HMCF became highly disordered after grafting GMA. • A novel method was explored to fulfill the surface functionalization of HMCF. [ABSTRACT FROM AUTHOR]

• Microstructural evolution of XPTFE were firstly studied using in-situ USAXS. • The size and spacing of scatterers are more unequal in XPTFE. • Lamellae crystals in XPTFE are elongated and thinned along the tension direction. • Broken crystals and voids in irradiated XPTFE are oriented with stretching. Cross-linked polytetrafluoroethylene (XPTFE) with excellent wear and radiation resistant is expected to be applied in strong radiation fields. In this study, synchrotron ultra-small angle X-ray scattering (USAXS) techniques combined with in-situ uniaxial stretching were firstly used to study the mechanical property degradation mechanism of XPTFE in terms of micro-structural evolution in real time. As the increase of cross-linking degree, the size and spacing of the scatterers for XPTFE were more unequal. When XPTFE was uniaxially stretched at room temperature, its molecular chains were tilted, and lamellae crystals were elongated and thinned along the stretching direction. When XPTFE was irradiated by γ-rays under air, with increasing absorbed doses, the long period decreased first and then increased, while the gyration radius was reversed. After high-dose irradiation, the mechanical properties of XPTFE were lost, making their stretching processes were dominated by the orientation of some small broken crystals along the stretching direction and accompanied by the formation of voids. But for XPTFE under constant stress uniaxial stretching at variable temperature, its chain segments and molecular chains cannot be oriented even at elevated temperatures, maintaining a degree of thermal stability. [ABSTRACT FROM AUTHOR]

• Local structures and thermophysical properties of molten NaF-BeF 2 are simulated by FPMD. • FPMD simulations without dispersion corrections give satisfactory densities of molten NaF-BeF 2. • 4-fold and 6-fold coordination structures are dominated for Be-F and Na-F between 673 and 1073 K. • The stability of Be-F bond determines to the heat capacity of molten NaF-BeF 2. • The strength of Na-F bond plays a key role on reducing viscosity of molten NaF-BeF 2. Molten NaF-BeF 2 has been proposed as one of the potential solvents and coolants for the Generation IV nuclear reactor, due to the lower price and satisfactory neutron capture cross-section. To gain comprehensive information on the structures and thermophysical properties of molten NaF-BeF 2 , FPMD simulations are applied to study its bond lengths, bond angles, and polyhedrons as well as the densities, specific heat capacity, thermal conductivities, and viscosities in the temperature range of 673–1073 K. These results show that 4- and 6-fold coordination structures of Be-F and Na-F are dominant in molten NaF-BeF 2 , respectively, and the diversity of Na-F polyhedral clusters originates from the inferior strength and stability of Na-F bonds. Besides, the Be-F bond is 6 times more stable than Na-F, whose strong stability leads to the large specific heat capacity (>1.5 J g−1 K−1) of NaF-BeF 2 , thereby the high ability of heat storage. Furthermore, the mapping relationship between the viscosity and structure of molten NaF-BeF 2 are revealed, where the Na-F bond plays a key role on reducing viscosity (<5 cP above 873 K) that makes its use as an industrial coolant possible. [ABSTRACT FROM AUTHOR]

Electrochemical corrosion of alloy materials is one of the biggest challenges in the development of heat transfer and storage technology by molten salt. Here, the thermodynamic and kinetic properties as well as microstructural characteristics of divalent alloying elements (M = Ni, Co, Fe, Mn, Cr, and Ti) in molten MgCl 2 –NaCl (MN) eutectic are analyzed based on first principles molecular dynamics (FPMD) simulations and electrochemical experiments, aiming to reveal corrosion rules of alloy and explain corrosion phenomenon. First, special thermodynamic cycles are designed to calculate the redox potentials of M 2+| M couples in molten MN, which are corrected by the experimental potential of Ni2+|Ni reference electrode. Then, ionic/atomic self-diffusion coefficients of molten salt mixtures are evaluated from FPMD simulations, whose credibility is verified by the results from cyclic voltammetry and chronopotentiometry. Studies have shown that the oxidation reaction of Ti are both thermodynamically and kinetically favorable, while the reactions of Fe and Cr are advantageous in thermodynamics and kinetics, respectively. Furthermore, the Ni enrichment on the alloy surface is explained by the larger diffusivity of Ni2+ than Ni in molten MN, thereby the deposition order of Ni > Mn > Co is deduced. Last, the dynamic coordination numbers and cage volumes of cation-Cl clusters are captured, where the delayed shuttle of Cl− in molten FeCl 2 -MN verifies the strongest stability of [FeCl 6 ]4− octahedral structure and the short activation time of Cl− in molten CrCl 2 -MN results in the fast corrosion rate of Cr. [Display omitted] • Redox potentials of divalent metals in molten MN were studied by FPMD and experiments. • Oxidation reactions of Fe and Cr are separately thermodynamically and kinetically favorable. • Metal deposition or dissolution depends on the ratio of diffusion coefficients of M 2+ and M. • Shuttle intensity of Cl− in M -centered coordination cages determines the corrosion rate of M. [ABSTRACT FROM AUTHOR]

The synchrotron radiation X-ray was used both as the irradiation source and testing tool for the PVDF membranes in-situ. The structural evolution of the PVDF membranes irradiated by the synchrotron radiation X-ray was analyzed by in-situ small angle X-ray scattering (SAXS)/wide angle X-ray scattering (WAXS) and ex-situ (ESR, FTIR and XRD) characterization methods. The alkyl radicals and carbon-carbon double bonds appeared in the irradiated PVDF membranes due to the irradiation effect, which confirmed that PVDF membranes first cracked, followed by cross-linked, during irradiation. The disappearance of the scattering peak at q = 0.05 Å−1 indicated that the synchrotron radiation X-ray destroyed the long periodic structure. The X-ray irradiation destroyed the crystalline region of the irradiated PVDF membranes, thus, leading to a decline in the crystallinity. Thus, overall, the in-situ irradiation and analysis could effectively monitor the structural evolution of the PVDF membranes during the radiation process and reduce the influence of time intervals between irradiation and measurement. • Synchrotron radiation X-ray is used as the radiation source and detection method. • 2.SAXS/WAXD were firstly monitored the internal structure evolution of PVDF in situ. • 3.Synchrotron radiation X-ray destroyed the long periodic structure of irradiated PVDF. • 4.In-situ radiation and analysis could effectively monitor structure evolution real time. [ABSTRACT FROM AUTHOR]

• Pyrolysis mechanism and products of bischofite was firstly obtained. • Pyrolysis temperature and heating rate will greatly affect the pyrolysis product. • High purity MgO was obtained after secondary calcination. • Mixture of MgO and Mg(OH)Cl coexisted at 550 and 600 °C. The thermal behavior of bischofite waste and MgCl 2 •6H 2 O was investigated by thermogravimetric analysis–derivative thermogravimetry (TGA-DTG) and X-ray diffraction (XRD). TGA-DTG results showed that the pyrolysis behavior and weight loss of bischofite were different from those of MgCl 2 •6H 2 O due to large number of impurities. The effects of temperature, atmosphere, and heating rate on the pyrolysis mechanism and products of bischofite were studied in detail by using XRD. The pyrolysis temperature remarkably affected the pyrolysis products. The mixture of MgO and Mg(OH)Cl coexisted at high temperatures of 550 and 600 °C. However, the presence of MgCl 2 was confirmed by calcination at 650 and 700 °C for 0.5 h except MgO. Through calcination at 700 °C for up to 2.0 h, the pyrolysis products of bischofite and MgCl 2 •6H 2 O were predominantly MgO, and the atmosphere had no effect on the content of MgO. Low heating rate was favorable for pyrolyzing bischofite into MgO, and the content of MgO reached 94.1% at the heating rate of 5.0 °C/min. After further purification by washing, the content of MgO in the final product increased to 99.0%. This study provided an effective route for the comprehensive utilization of bischofite resources in salt lakes. [ABSTRACT FROM AUTHOR]

NaCl–KCl–CaCl 2 eutectic salt was developed using the thermodynamic calculation and experimental validation for the ultra-high-temperature thermal storage. Substitutional solution model (SSM) was used to describe the liquid phase and solid solution phase, and stoichiometric compound was applied to depict the intermediate phase. The predicted eutectic temperature (481.3 °C) of NaCl–KCl–CaCl 2 eutectic salt agrees well with experimental value (496.3 °C). The actual eutectic point of NaCl–KCl–CaCl 2 system is placed at T = 496.3 °C, X NaCl = 0.408 mol, X KCl = 0.075 mol and X CaCl2 = 0.517 mol. The fusion enthalpy is 171.5 J/g. The weight loss is only 1.7 wt% even at 900.0 °C and 939.0 °C is determined to be the upper limit of working temperature. The average liquid specific heat capacity is 0.80 ± 0.15 (J/g⋅oC). The cost of NaCl–KCl–CaCl 2 eutectic salt is only 51.6% of solar salt and 54.3% of NaCl–KCl–MgCl 2 salt. SSM of thermodynamic calculation can be used as a reasonable model to optimize the chlorides salts in future. The developed NaCl–KCl–CaCl 2 eutectic salts have relatively better thermo-physical properties particularly excellent ultra-high-temperature thermal stability and lower cost, and can be considered as the ultra-high-temperature thermal energy storage materials. ∙NaCl–KCl–CaCl 2 salts were developed by thermodynamic calculation and experiment. ∙The calculated eutectic point agrees well with the experimental result. ∙The decomposition temperature of NaCl–KCl–CaCl 2 salt is 939.0 °C. ∙NaCl–KCl–CaCl 2 salts have better thermo-physical properties and lower cost. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phase transition behavior of MgCl 2 -KCl is revealed from thermophysical properties. • Microstructural and kinetic characteristics are studied by FPMD and experiments. • 5- and 4-fold coordination dominate the K-Cl and Mg-Cl coordinated structures. • Pre-peak of static structural factor is primarily attributed to Mg-Mg across networks. First principle molecular dynamics (FPMD) simulations coupled with experimental measurements are used to investigate the thermophysical parameters, microstructures, and thermal transport properties of the MgCl 2 -KCl (32:68 mol%) eutectic salt. The phase transition behaviors are charactered by the thermal expansion coefficient, density, enthalpy of fusion, and specific heat capacity through FPMD simulations, and the simulated results cohesive well with those of our experiments. From the temperature dependences of radial distribution functions g (r) and coordination numbers, the mutations of peak heights of g K - Cl (r) and g Mg - Cl (r) near the melting point are related to the phase change, and the coordination structure of K-Cl is significantly changed from 6-fold to 5-fold with increasing temperature. Moreover, the prominent peaks in static structural factors are attributed to charge alternation structures of cation-Cl clusters, while pre-peaks are dominated by the Mg-Mg correlation. Based on ionic self-diffusion coefficients, the calculated thermal conductivity and shear viscosity of molten MgCl 2 -KCl are slightly lower than our experimental values. Nevertheless, the FPMD simulations provide an appropriate approach to evaluate the thermodynamic and kinetic properties of MgCl 2 -KCl eutectic, which contributes essential data for designing the heat transfer and storage system. [ABSTRACT FROM AUTHOR]

Carbon materials have appealing potential as anode for Potassium ion batteries (KIBs), but achieving low-potential plateau curve and high energy density for anode materials is a primary challenge. Herein, a 3D holey reduced graphene oxide/ carbon nanotubes (L-HRGO/CNT) film was constructed via chemical etching and low- temperature drying method. The micro/mesoporous in graphene oxide (GO) sheets are created by chemical etching, which shorts ion transfer distance, and thus increases the K+ intercalation/deintercalation rate. During low-temperature drying process, the water molecules inside the GO interlayer serve as self-sacrificial spacers for extending the stacked structure and maintaining integrity, increasing capacity contributed from K+ intercalation for a low discharge voltage. And the CNTs introduced into the film via vacuum co-filtration can enhance the conductivity and mechanical strength of the film. The optimized L-HRGO/CNT film delivered a high K+ storage capacity of 307.0 mA h g−1, high-rate capability, and the capacity retention reaches 72.6% at 200 mA g−1 for 200 cycles. When assembled with the KVPO 4 F cathode, the reversible capacity remains 93.8 mAh g−1 after 100 cycles, and 473.0 Wh kg−1(776.9 Wh L−1) of the energy density is achieved. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermophysical properties and microstructures of molten NaCl-KCl-NaF are simulated by FPMD. • Excellent thermal energy storage and conductivity are explained from local structures. • FPMD with DFT-D3 dispersion correction is prominent in evaluating energy storage density. • Radial and angular distributions involving K and F are extremely susceptible to temperature. • Mean viscosity of molten NaCl-KCl-NaF from 923 to 1123 K is predicated as 1.308 cP. Ternary NaCl-KCl-NaF eutectic salt is a promising thermal storage and heat transfer medium for the application of high-temperature concentrated solar power due to the high energy density and thermal conductivity. However, the relationships between these properties and structures of NaCl-KCl-NaF eutectic cannot be well explained by experiments, and thus the first principles molecular dynamics (FPMD) simulations technique stands out. In the work, the initial models of molten NaCl-KCl-NaF are constructed based on experimental densities, the energy storage density and thermal conductivity are evaluated via FPMD simulations, and the origins of the two properties are explained from the microstructures of radial and angular distribution functions. It is concluded that the strong coordinated solvation shell of Na-F results in the high energy storage density. And the orientations of Cl-Cl-Cl bond angle are enlarged by addition of F anions, thereby enhancing the thermal diffusion coefficient. Finally, the viscosities of molten NaCl-KCl-NaF from 923 to 1323 K are predicted by FPMD based on the diffusion coefficient and solvodynamic mean radius, suggesting that some anions of KCl and NaF are exchanged with each other above 1123 K. Overall, these simulation results are helpful to understand the performance improvement of molten alkali halides, and to replenish and modify the molten salt database. [ABSTRACT FROM AUTHOR]

The corrosion behaviour of 316 stainless steel in NaCl-KCl-MgCl 2 salt vapour at 700 °C under static conditions was investigated in this experiment. Easy-to-peel oxide layers were formed on the surface, and their composition and structure changed as exposure continued. The initially formed oxide monolayer was gradually transformed into oxide multilayers, and the outermost layer changed from Cr-Fe oxide to Mg-Cr oxide. The evolution of surface oxide layers was due to the varying diffusion rates of elements in 316 stainless steel as well as to the differing reaction rate of MgCl 2 in the salt vapour. • Corrosion process of 316 SS in NaCl-KCl-MgCl 2 salt vapor was investigated at 700 °C. • Loose oxides layers were formed on 316 SS surface in the molten salt vapor. • Composition and structure of oxides layers evolved with vapour exposing time. • Oxide layer evolution reveals the corrosion mechanism of 316 SS in salt vapor. [ABSTRACT FROM AUTHOR]

A purification protocol of molten MgCl 2 -NaCl-KCl (MNK) by adding active metals has been proposed to reduce the corrosion of alloy materials in the application of generation III concentrating solar power plants. In this work, the ionic transport properties and micro structural characteristics of metals (Mg, Na, and K) and molten MNK mixtures (metal -MNK) are investigated at 723 K by first principles molecular dynamics (FPMD) simulations. According to the evolution of total energy, the Mg -MNK is the most stable mixture, while the Na -MNK mixture has larger energy fluctuations resulting in a higher specific heat capacity. Studies have shown that the small amount of metal existing in the molten MNK has almost no effect on the ionic diffusion order, but total diffusion coefficients and thermal conductivities of metal -MNK mixtures are improved. Meanwhile, the intensity of diffracted light of molten MNK is weakened by metals, and the microstructures of molten MNK added with alkali metals are more susceptible than that with metallic Mg by analyzing the total and partial static structure factors. Furthermore, the intermediate range orders of metal- MNK are demonstrated, especially for Mg-Mg pairs hinting the formation of the Mg2+-void-Mg2+ structure or Mg2+-centered clusters. Overall, the FPMD results deeply elaborate the dynamic interactions of molten MNK and metallic particles, which give insights for the development of salt purification and corrosion inhibition technology. • Dynamic interactions between molten MNK and active metals were simulated by FPMD. • Time evolutions of density and total energy of molten metal -MNK mixtures were depicted. • Ionic diffusion coefficients and thermal conductivities of molten metal -MNK were evaluated. • Effects of Mg, Na, and K metals on microstructures of molten MNK were elaborated. [ABSTRACT FROM AUTHOR]

The mesophase pitch derived graphite foams with low bulk density (L-GF) and high bulk density (H-GF) were spontaneously infiltrated by erythritol to prepare graphite foam/erythritol (GF/erythritol) phase change materials (PCMs) with ultrahigh thermal conductivity for medium temperature thermal energy storage applications. Results of thermophysical properties indicated that thermal diffusivity of the GF/erythritol PCMs can be enhanced by 66 and 117 times as compared with that of pristine erythritol in solid (0.36 mm2/s). This enhancement resulting from three-dimensional ordered network of graphite foam can significantly reduce the charging and discharging time of the PCM storage system. Although H-GF as a matrix can obtain a higher thermal conductivity (68.71 W/(m·K)) than L-GF (40.52 W/(m·K)), the smaller porosity cannot allow more erythritol to be absorbed, and its melting enthalpy (178.4 J/g) is lower than L-GF (266.6 J/g). In addition, the enhancement of thermal conductivity and the increase of interfacial surface area caused by graphite foam structure strongly suppresses the supercooling of erythritol, which can be reduced from 86.0 °C to 53.2 °C. The obtained results demonstrated that the GF/erythritol PCM as a stable PCM is a promising material for medium temperature thermal energy storage applications. • The phase change material with ultrahigh thermal conductivity was obtained. • The supercooling of erythritol can be effectively suppressed. • The graphite foam forms supply a path for heat transferring rapidly. • Increasing grain size of erythritol also contributes to the heat transfer rapidly. [ABSTRACT FROM AUTHOR]

PAN fibers were irradiated by electron-beam at room temperature in air. The micro-void structure transformation and properties of irradiated PAN fibers were characterized using gel permeation chromatograph, small angle X-ray scattering, differential scanning calorimetry, thermogravimetric analysis and tensile strength. The cross-linking occurred dominantly, and the stable polymer network formed. The gel fraction got saturated at 200 kGy and did not further increase due to the oxidation degradation. The lateral size of micro-voids and the dose were negatively correlated while the length and misorientation of micro-voids expanded with dose increased (61.73 nm–201.06 nm, 7.79°–11.86°). The intense heat release of cyclization reaction was efficiently relieved by irradiation. Meanwhile, carbon yield at 800 °C also increased from 43% to 55% after irradiation at 200 kGy, which increased by 25% compared with original PAN fibers. This study can prefer irradiation conditions to improve PAN based carbon fiber property. • SAXS was firstly used to study the micro-voids structure of irradiated PAN fibers. • Transformation of micro-voids led to a decline in mechanical properties. • Crosslinking caused a reduction in the lateral size of micro-voids for PAN fibers. • Carbon yield at 800 °C increased to 54.9% after irradiation. [ABSTRACT FROM AUTHOR]

• Free radicals of PAN nano-fibers were stable in vacuum but decayed fast in air. • The polyimine radicals show higher stability at room and elevated temperatures. • Radiation oxidation occurred throughout PAN nano-fibers due to smaller diameter. • Radiation oxidation facilitated dehydrogenation to drive the stabilization process. Radiation technique was found to accelerate the stabilization process of PAN nano-fibers in the production of carbon nano-fibers. The evolution and decay of the free radicals of electrospun PAN nano-fibers induced by gamma-rays irradiation were investigated using electron spin resonance. Mainly alkyl and polyimine radicals were formed and the total free radical concentration reached saturation of 1.3×1019spins/g at the dose of 200 kGy in vacuum. The free radicals were very stable with a half-life period longer than 40 days in vacuum but rapidly decayed in air. PAN nano-fibers were subject to radiation oxidation due to their small diameter when irradiated in air. The polyimine radicals were found to be more stable than alkyl radicals at room and elevated temperatures. Mainly polyene radicals were formed resulting from dehydrogenation during the stabilization process and the irradiated sample always contained higher radical concentration. The radiation oxidation facilitated the dehydrogenation to drive the thermal stabilization process. [ABSTRACT FROM AUTHOR]

Efficient preparation of microwave absorbers with thin thickness, strong absorbance, broad bandwidth and low filler loading remains a significant challenge. In this study, copper ferrite/reduced graphene oxide composites were synthesized by a one-pot hydrothermal method. The chemical composition, phase structure and micromorphology were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscope, scanning electron microscope and transmission electron microscope. The characteristics of electromagnetic were assessed on a vector network analyzer. Results show that the content of graphene oxide greatly influences the microwave absorption properties of copper ferrite/reduced graphene oxide composites. The maximum reflection loss value of composites was −58.7 ​dB ​at 9.2 ​GHz with a thickness of 2.56 ​mm, when the primitive amount of graphene oxide was 20 ​mg. At the same time, the effective bandwidth can reach 5.2 ​GHz under merely 1.85 ​mm. The brilliant performance of microwave absorption is usually ascribed to multi-dipole polarization and outstanding impedance matching. This work supplies guidance for designing absorbers that are lightweight, wideband, and strong absorption ability. Fig. 9. Electromagnetic parameters (a), (b), (c) and (d); dielectric loss (e), magnetic loss (f). [Display omitted] • CuFe 2 O 4 /RGO composites were synthesized via a simple hydrothermal method. • The maximum reflection loss was -58.7 ​dB ​at 9.2 ​GHz with a thickness of 2.56 ​mm. • The effective absorption band was 5.2 ​GHz under merely 1.85 ​mm. • Good microwave absorption owe to multi-dipole polarization and impedance matching. [ABSTRACT FROM AUTHOR]

• Corrosion behaviour of Ni-Mo-Cr alloy in NaCl-KCl-MgCl 2 salt vapour was investigated at 700 °C. • Oxidation and further reaction in NaCl-KCl-MgCl 2 salt vapour accelerate the alloy corrosion. • A loose double layer of Cr, Mo and Mg oxide was formed in the molten salt vapour. • The corrosion of molten salt vapour to alloy is serious in practical application. The corrosion behaviours of Ni-Mo-Cr alloy samples immersed in NaCl-KCl-MgCl 2 salt and vapour were investigated at 700.0 °C for 100 h. The surface layer of the corroded alloy in liquid molten salt exhibited slight Cr depletion. The alloy formed a loose double layer of Cr, Mo and Mg oxide in the vapour. The oxidation with Mg chloride in the salt vapour accelerated corrosion of the sample, and its Cr-depleted depth was nearly twice that of a sample immersed in liquid molten salt. The corrosion of an alloy by salt vapour must not be neglected in practical applications. [ABSTRACT FROM AUTHOR]

The NaCl–KCl–NaF eutectic salt was designed and developed by Pandat software and experiment. Thermal transport and storage performances were determined by experimental measurements. The melting point of the NaCl–KCl–NaF eutectic salt is 604.1 °C and the fusion enthalpy is up to 398.4 J/g. The thermal conductivity average value was 1.037 ± 0.074 W/m−1·°C−1. The weight loss of NaCl–KCl–NaF eutectic salt is still less than 6.0% even up to 900 °C and the eutectic salt have very excellent thermal stability. The NaCl–KCl–NaF eutectic salt with high latent and suitable temperature have good economy performance even with expensive individual salt of NaF. The NaCl–KCl–NaF eutectic salt with suitable phase change temperature, low cost, high latent heat, excellent stability and good economy performance can be a candidate phase change material for next generation concentrated solar power with supercritical CO 2 cycles. • NaCl–KCl–NaF eutectic salts were designed and developed by Pandat and experiment. • T m of the eutectic salts is 604.1 °C and the fusion enthalpy is up to 398.4 J/g. • The eutectic salts have very excellent thermal stability. • The eutectic salts with high latent & suitable temperature have good economy performance. [ABSTRACT FROM AUTHOR]

Running condition fretting map has long been recognized as a useful tool for investigating fretting wear. It illustrates the fretting condition for a fretting couple under different displacement amplitudes and loads, which is of great significance for the fretting research. However, it requires a large amount of data to draw running condition fretting map for only one fretting couple, therefore, it is urgent to find a simple method to illustrate the fretting condition. In this paper, the cross-linked polytetrafluoroethylene (XPTFE) with excellent mechanical properties was fabricated by electron beam irradiation. Based on the tribological behavior of XPTFE and PTFE under different displacement amplitudes, it was found that the ratio of static friction force to deformation (F s / Δ d) can be further used to analyze the fretting behavior of fretting couple under specific running conditions. In addition, the F s / Δ d value is closely related to the mechanical properties of the fretting couples. This study provides a new solution for exploring the mechanical properties and running conditions for fretting couples. • The cross-linked PTFE (XPTFE) with branched 3D network structure is fabricated by electron beam irradiation. • The XPTFE obtains a high hardness and low elastic modulus, and displays a higher wear resistance than PTFE. • XPTFE with low ratio of static friction force to deformation F s / Δ d is prone to be in the partial slip regime. • The fretting running status can be inferred by the mechanical properties of tribo-pairs and certain running conditions. [ABSTRACT FROM AUTHOR]

• A simple pretreatment method to improve the yield and stability of the free radicals was reported. • Crystalline transformation, compacted spatial structure are responsible for high concentration and stability. • Radical concentration increased 10 times at 25 kGy. The half-life time of free radicals is 10 times. Silk fibroin determines the perseverance of silk-based materials. The samples of silk fibroin were pretreated combined alkali/urea system with rapid freezing in liquid nitrogen. The structural changes of unpretreated and pretreated silk fibroins were investigated by XRD, SAXS and FTIR. The results indicate that part of the amorphous region was transformed into silk-II crystalline structure, and the radius of gyration decreased due to the folding of molecular chains by hydrogen bonds. The free radicals of unpretreated and pretreated silk fibroin induced by electron beam irradiation were studied by electron spin resonance (ESR). The results indicate that the radical concentration increased by 10 times at 25 kGy and attained 8.04*1019 spins·g−1 at 50 kGy after pretreatment, which is comparable to the saturated radical concentration of unpretreated silk fibroin above 200 kGy. And the half-life time of free radicals is 10 times longer than that of the unpretreated samples. The higher stability of the free radicals is considered to be related to the protein structure changes induced by pretreatment and this can provide convenience for silk irradiation grafting. The new pretreatment method may provide inspiration for designing protein structures to regulate free radical formation. [ABSTRACT FROM AUTHOR]

The first principle molecular dynamics (FPMD) simulations in combination with experimental measurements are applied to investigate the thermophysical properties and structural evolution of MgCl 2 –NaCl–KCl (MNK) eutectic. The densities, melting point, and enthalpy of fusion simulated by FPMD within NPT ensemble are consistent with experimental results. Besides, the thermal conductivity of molten MNK eutectic evaluated from FPMD simulations with NVT ensemble gives satisfactory result. Furthermore, the shear viscosities of MNK eutectic are deduced based on ion self-diffusion coefficients and solvodynamic radius, similar to the data estimated by additive contribution method. Eventually, the change rules of radial and angular distribution functions and structural factor of MNK eutectic during melting are revealed, and the melting mechanism is proposed from the evolution of polyhedral coordination structures. These results are heuristic in structure-activity relationship of MNK eutectic, which sheds insight for further development of efficient heat transfer and storage media through microstructure engineering. • Thermophysical properties of MgCl 2 –NaCl–KCl (MNK) eutectic were simulated by FPMD. • Density and thermal diffusivity of molten MNK were first determined experimentally. • Microstructural evolution of MNK eutectic during melting was elaborated. • Relationship of structure and viscosity of MNK eutectic was revealed. [ABSTRACT FROM AUTHOR]

• The effect of graphite particles in molten FLiNaK salt on the corrosion behavior of GH3535 alloy was investigated. • Graphite particles in molten salt barely affect the corrosion rate of chromium in GH3535 alloy. • Graphite particles promote carbonization and corrosion of Mo, which is originally stable in the molten fluorine salt. The corrosion behaviours of GH3535 alloy in molten FLiNaK eutectic salt (LiF-NaF-KF: 46.5–11.5–42.0 mol.%) were investigated in the presence and absence of graphite particles by using a static immersion corrosion technique. Results indicated that graphite particles barely affected the corrosion rate of chromium in the subsurface and increased the corrosion loss of GH3535 alloy in molten salt. These seemingly contradictory results were obtained because the introduction of graphite particles into the molten FLiNaK eutectic salt carbonized and corroded molybdenum, which is one of the most stable elements in the Ni-Mo-Cr alloy in molten FLiNaK salt. [ABSTRACT FROM AUTHOR]

Layered nickel-rich cathode materials such as LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) possess huge potential in developing high-performance secondary batteries. However, the micron-sized particles of NCM523 in electrode laminates produce spacious interparticle voids (electronically dead zones) which dampen the charge transference and cause bulk material degradation after interaction with the excessive liquid electrolyte within the voids, thus alarming their safe and confident use in batteries. In this context, we hereby ex-situ synthesize a highly electro-ionically conductive pure La 4 NiLiO 8 for potential use as a voids-filling agent in enhancing the electrochemical performance and durability of the layered energy storage NCM523. The morphological and crystallinity analyses in conjunction with the thermal treatments confirm high stability of La 4 NiLiO 8 up to 1150 °C, exceptionally low resistances, and fast charge conduction (335 mS cm−1). A simplistic but scientifically important filling of the inter-particle voids with only 6% of La 4 NiLiO 8 decreases the charge transfer resistance from 103.2 to 19 Ω cm2, increases the discharge capacity from 185 mAh g−1 to 214 mAh g−1 at 0.2C, and enhances the capacity retention from 58.9 to 81.5% (after 500 cycles at 1C). Thus, the excellent physico-thermo-electrochemical characteristics and stability of La 4 NiLiO 8 as a voids-filling agent are highly beneficial for developing high-performance safe secondary batteries. Image 1 • Bacillus-shaped pure La 4 NiLiO 8 of high conductivity and thermal stability is synthesized. • Detailed electrochemical analysis infers extremely low resistances and fast charge conduction. • The La 4 NiLiO 8 showed highly beneficial role as a voids-filling agent in Nickel-rich materials. • The La 4 NiLiO 8 has remarkably improved the stability and electrochemical performance of NCM523. [ABSTRACT FROM AUTHOR]

• Corrosion behaviors of 316SS were studied in purified NaCl-MgCl 2 eutectic salt. • Good corrosion resistance of 316SS was found in purified NaCl-MgCl 2 at 600°C. • 316SS corrosion rate in purified NaCl-MgCl 2 was very low even at 700 °C. • Corrosion mechanisms of 316SS in purified NaCl-MgCl 2 were obtained. The effects of temperature on the corrosion of 316 stainless steel (316SS) in purified NaCl-MgCl 2 eutectic salt under Ar were investigated through immersion test. The corrosion of samples accelerated and intergranular corrosion became obvious with increased temperature. The corrosion of 316SS was attributed to the selective dissolution of Cr, and corrosion had strong temperature dependence. The corrosion mechanism under the NaCl-MgCl 2 eutectic salt was the combined effect of a dissolution mechanism with matrix metal element, which was attributed to the accelerating effect of surface chromium-dissolution and intergranular-diffusion rates with increased molten salt temperature. [ABSTRACT FROM AUTHOR]

• The Effect of graphite particles in molten FLiNaK salt on the corrosion behavior of 316H stainless steel was studied. • Carbon from the graphite particles in the molten FLiNaK eutectic salt diffused into the 316H stainless steel. • The rate of carbide formation on the 316H stainless steel surface was lower than the Cr corrosion rate. • Higher graphite particle concentration in molten FLiNaK eutectic salt caused server corrosion of 316H stainless steel. The effect of various concentrations of graphite particles in molten FLiNaK eutectic salt (LiF-NaF-KF: 46.5-11.5–42.0 mol.%) on the corrosion behaviour of 316H stainless steel was investigated using a static immersion corrosion technique. Higher graphite particle concentration caused severer corrosion. Weight loss, Cr depletion distance, and surface Cr carbide concentration were positively correlated with graphite particle concentration in molten FLiNaK eutectic salt. Carbon from the graphite particles in the molten FLiNaK salt diffused into the 316H stainless steel and formed Cr carbides. The rate of carbide formation on the 316H stainless steel surface was much lower than the Cr corrosion rate. [ABSTRACT FROM AUTHOR]

MgO has broad application potential in CO 2 capture at intermedium temperatures. In this paper, the effects of NaNO 3 doping on the properties of MgO prepared by using waste bischofite as the raw material were investigated to improve the performance of the CO 2 capture. MgO-doped NaNO 3 exhibited excellent CO 2 capture performance at 320 °C with a maximum adsorption capacity of 36.62 wt %. MgO-doped NaNO 3 has good cycling stability after 10 adsorption-desorption cycle experiments. In addition, CO 2 adsorption on pure MgO and MgO-NaNO 3 surfaces was investigated in accordance with density functional theory. Calculation results show that doping with NaNO 3 allows more electrons to be transferred from the MgO substrate to the CO 2 molecule. MgO-doped NaNO 3 can lead to an increase in adsorption energy, resulting in a more stable structure after adsorption and thereby promoting adsorption. The result of this study provides an effective method for the comprehensive utilization of salt lake resources.

Molten MgCl 2 -based chlorides have emerged as potential thermal storage and heat transfer materials due to high thermal stabilities and lower costs. In this work, deep potential molecular dynamics (DPMD) simulations by a method combination of the first principle, classical molecular dynamics, and machine learning are performed to systemically study the relationships of structures and thermophysical properties of molten MgCl 2 -NaCl (MN) and MgCl 2 -KCl (MK) eutectic salts at the temperature range of 800-1000 K. The densities, radial distribution functions, coordination numbers, potential mean forces, specific heat capacities, viscosities, and thermal conductivities of these two chlorides are successfully reproduced under extended temperatures by DPMD with a larger size (5.2 nm) and longer timescale (5 ns). It is concluded that the higher specific heat capacity of molten MK is originated from the strong potential mean force of Mg-Cl bonds, whereas the molten MN performs better in heat transfer due to the larger thermal conductivity and lower viscosity, attributed to the weak interaction between Mg and Cl ions. Innovatively, the plausibility and reliability of microscopic structures and macroscopic properties for molten MN and MK verify the extensibilities of these two deep potentials in temperatures, and these DPMD results also provide detailed technical parameters to the simulations of other formulated MN and MK salts.

The lack of suitable cathode materials with a high capacity and good stability is a crucial problem affecting the development of aqueous Zn-ion batteries. Herein, a novel strategy for the modification of V 2 CT x through molten salt thermal treatment is proposed. In the novel route, S heteroatoms were introduced into V 2 CT x through a substitution reaction during the dissolution of Li 2 S in LiCl-KCl molten salts. Then, surface V 2 O 5 was obtained through the in situ electrochemical charging/discharging of the S-doped V 2 CT x (MS-S-V 2 CT x ) cathode. The assembled Zn/MS-S-V 2 CT x battery showed a high reversible discharge capacity of 411.3 mAh g -1 at a current density of 0.5 A g -1 , an 80% capacitance retention after long cycle stability tests at 10 A g -1 for 3000 cycles, and a high energy density of 375.5 Wh kg -1 in 2M ZnSO 4 . Density functional theory calculations demonstrate that the improved electrochemical performance of the cathode can be attributed to the introduced S heteroatoms, which considerably reduced the ion diffusion energy barrier for Zn 2+ ions and improved the stability of V 2 O 5 . This work provides a novel method to produce highly active and stable vanadium-based cathodes for aqueous Zn-ion batteries.

Corrosion behavior of 304 stainless steel in molten NaNO 3 -NaCl-NaF salt and NaNO 3 -NaCl-NaF vapor has been studied at 450 °C. The results showed that the samples suffered weight loss, and surface oxides, i.e. Fe 2 O 3 and FeCr 2 O 4 characterized by XRD, were formed after corrosion. The surface oxide layer was about 1.1 μm in thickness after corrosion in molten NaNO 3 -NaCl-NaF salt, which was relatively homogeneous and dense. Whereas, the distribution of surface oxides was not even, and a shedding phenomenon was observed after corrosion molten NaNO 3 -NaCl-NaF vapor. This is mainly attributed to the existence of NO 2 and NO in the molten NaNO 3 -NaCl-NaF vapor determined by thermogravimetric infrared spectroscopy, which affected the adherence between oxides and the matrix. Additionally, the corrosion rate of 304 stainless steel in molten NaNO 3 -NaCl-NaF salt is almost close to that in solar salt, which demonstrates that the synergy influence of Cl - and F - on the rate of 304 stainless steel is not significant. This work not only enriches the database of molten salt corrosion, but provides references for the selection of alloy and molten salt in the CSP., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

Silicate-carbonate mixtures as new CO2 capture agents have the latent application potential. CO2 sorption or desorption processes using the Na4SiO4-Na2CO3 mixture sorbent in air were analyzed by in situ Raman spectroscopy and X-ray diffraction from 25 °C to 900 °C. The results show that the Na4SiO4-Na2CO3 mixture sorbent could continuously absorb and strip CO2 by thermal swinging. The CO2 sorption was produced via a two-step process depending on the temperature range. Initially, CO2 dissolved in carbonate to produce pyrocarbonate (C2O52-) ions, which subsequently reacted with SiO44- anion to produce the polymer silicates and CO32- anion. The C2O52- anion on the surface of the silicates promoted CO2 transformation to CO32- anion through the reaction with SiO44- anions. The CO32- anion decomposed the polymer silicates to produce orthosilicates and CO2 gas again at high temperature. By this circulation, CO2 could dissolve in carbonate more easily and be absorbed and stripped continuously by thermal swinging in the mixture sorbent than the pure carbonate. The processes of recovering heat and separating CO2 from flue gas simultaneously without decreasing the temperature is an economical and attractive method for energy conservation. It offers the theoretical basis for developing new heat-storage and CO2-capture technology.

Background: Infection is a serious potential consequence of surgery to complete a spontaneous abortion. Antibiotic prophylaxis before some operations has been shown to reduce the risk of postoperative infections. However, for miscarriage surgery, evidence is lacking to show effectiveness., Methods: In this systematic review, the electronic databases of Cochrane Central Register of Controlled Trials, EMBASE, and PUBMED will be searched from inception to May 1, 2020. Randomized controlled trials that assessed the effectiveness and safety of antibiotic prophylaxis for preventing infection for patients undergoing miscarriage surgery will be included. All process of the study selection, data extraction, and methodology evaluation will be carried out by two authors independently. RevMan 5.3 software will be utilized for statistical analysis., Results: This study will provide a detailed summary of latest evidence related to the effectiveness and safety of antibiotic prophylaxis for preventing infection for patients undergoing miscarriage surgery., Conclusion: The findings of this study may provide possible guidance for the use of antibiotic prophylaxis for preventing infection for patients undergoing miscarriage surgery., Dissemination and Ethics: Ethical approval is not required in this study, because it will not collect the original data from individual patient. The results are expected to publish through a peer-reviewed journal., Systematic Review Registration: PROSPERO CRD CRD42020155643.

Intermediate temperature NaCl-AlCl 3 -based Al-ion batteries are considered as a promising stationary energy storage system due to their low cost, high safety, etc. However, such a cheap electrolyte has a critical feature, i.e., strong corrosion, which results in the short cycle life of the conventional Al-metal anode and also limits the development of the NaCl-AlCl 3 -based Al-ion batteries. A noncorrosive electrolyte may be a good choice for addressing the above challenge, while it is difficult to obtain the electrolyte that has advantages of both noncorrosion and low cost. Therefore, here, we report a Ga-metal anode in the affordable NaCl-AlCl 3 electrolyte for constructing a long-life stationary Al-ion energy storage system. This featured liquid metal anode shows good alloying and dealloying processes between metallic Ga and Al, as well as renders superior stability of the interface between the electrolyte and the anode (e.g., smoothly running for over 580 h at 2 mA cm -2 ). No-corrosion and no-pulverization problems appear in this novel liquid/liquid interface. Those advantages demonstrate that the liquid Ga-metal anode has a great promise for the improvement of the NaCl-AlCl 3 -based Al-ion batteries for large-scale stationary energy storage applications.

Treating water that has been polluted with chemical dyes is an important task related to water resources. Advanced oxidation processes are highly efficient for the destruction of organic contaminants. In this study, a Co 3 O 4 /graphene oxide (GO)/polyacrylonitrile (PAN) filter membrane was prepared through hydrothermal synthesis followed by vacuum filtration. The samples were characterised using different methods. The results showed that the Co 3 O 4 /GO sheets securely entered the voids of the PAN nanofibres. The Co 3 O 4 /GO/PAN filter membrane demonstrated the effective degradation of the organic dye Orange II, with a degradation rate of 93.5949%. The degradation rate remained at a high level after five cycles. The Co 3 O 4 /GO/PAN filter membrane has huge potential for application in industrial dye wastewater treatment., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

This data article includes the supplementary database material for the manuscript "Thermodynamic description for the NaF-KF-RbF-ZnF 2 system", (Tang et al., 2018). We present all the thermodynamic parameters used and optimized model parameters of the thermodynamic database of the NaF-KF-RbF-ZnF 2 quaternary system, by which researchers can obtain the calculated phase diagrams. What׳s more, the comparison of calculations with experimental lattice constants of all compounds and relative deviations of unit cell parameters between before and after structure optimization for the NaF-KF-RbF-ZnF 2 system are demonstrated in this work. Meanwhile, we provide the calculated mixing enthalpy in the binary AF-ZnF 2 (A=Na, K and Rb) and AF-RbF (A=Na and K) system, which are helpful for researchers to better understand the system. These supplementary databases are most useful in understanding the manuscript (Tang et al., 2018).

Background: Studies on environmental exposures during pregnancy commonly use maternal residence at time of delivery, which may result in exposure misclassification and biased estimates of exposure and disease association. Studies on residential mobility during pregnancy are needed in various populations to aid studies of the environmental exposure and birth outcomes. However, there is still a lack of studies investigating residential mobility patterns in Asian populations., Methods: We analyzed data from 10,542 pregnant women enrolled in a birth cohort study in Lanzhou, China (2010-2012), a major industrial city. Multivariate logistic regression was used to evaluate residential mobility patterns in relation to maternal complications and birth outcomes., Results: Of the participants, 546 (5.2%) moved during pregnancy; among those who moved, 40.5%, 34.8%, and 24.7% moved during the first, second, and third trimester, respectively. Most movers (97.3%) moved once with a mean distance of 3.75 km (range: 1-109 km). More than half (66.1%) of the movers moved within 3 km, 13.9% moved 3-10 km, and 20.0% moved > 10 km. Pregnant women who were > 30 years or multiparous, or who had maternal complications were less likely to have moved during pregnancy. In addition, movers were less likely to deliver infants with birth defects, preterm births, and low birth weight., Conclusions: Residential mobility was significantly associated with several maternal characteristics and complications during pregnancy. The study also showed a lower likelihood of adverse birth outcomes among movers than non-movers, suggesting that moving might be related to reduce exposure to environmental hazards. These results confirm the hypothesis that residential mobility may be important with respect to exposure misclassification and that this misclassification may vary by subpopulations., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A complete and ordered layered structure on the surface of LiNi 0.815 Co 0.15 Al 0.035 O 2 (NCA) has been achieved via a facile surface-oxidation method with Na 2 S 2 O 8 . The field-emission transmission electron microscopy images clearly show that preoxidation of the hydroxide precursor can eliminate the crystal defects and convert Ni(OH) 2 into layered β-NiOOH, which leads to a highly ordered crystalline NCA, with its (006) planes perpendicular to the surface in the sintering process. X-ray photoelectron spectroscopy and Raman shift results demonstrate that the contents of Ni 2+ and Co 2+ ions are reduced with preoxidization on the surface of the hydroxide precursor. The level of Li + /Ni 2+ disordering in the modified NCA determined by the peak intensity ratio I (003) /I (104) in X-ray diffraction patterns decreases. Thanks to the complete and ordered layered structure on the surface of secondary particles, lithium ions can easily intercalate/extract in the discharging-charging process, leading to greatly improved electrochemical properties.

Importance: Exposure to ambient particulate matter during pregnancy has been suggested as a risk factor for preterm birth. However results from limited epidemiologic studies have been inconclusive. Very few studies have been conducted in areas with high air pollution levels., Objective: We investigated the hypothesis that high level exposure to particulate matter with aerodynamic diameter no larger than 10μm (PM10) during pregnancy increases the risk of preterm birth., Methods: A birth cohort study was carried out between 2010 and 2012 in Lanzhou, China, including 8969 singleton live births with available information on daily PM10 levels from four monitoring stations, individual exposures during pregnancy were calculated using inverse-distance weighting based on both home and work addresses. Unconditional logistic regression modeling was used to examine the associations between PM10 exposure and risk of preterm birth and its clinical subtypes., Results: Increased risk of very preterm birth was associated with exposure to PM10 during the last two months of pregnancy (OR, 1.07; 95%CI, 1.02-1.13 per 10μg/m(3) increase for last four weeks before delivery; 1.09; 1.02-1.15 for last six weeks before delivery; 1.10; 1.03-1.17 for last eight weeks before delivery). Compared to the U.S. National Ambient Air Quality Standard (150μg/m(3)), higher exposure level (≥150μg/m(3)) of PM10 during entire pregnancy was associated with an increased risk of preterm birth (1.48; 1.22-1.81) and the association was higher for medically indicated preterm birth (1.80, 1.24-2.62) during entire pregnancy and for very preterm during last 6weeks before delivery (2.03, 1.11-3.72)., Conclusions and Relevance: Our study supports the hypothesis that exposure to high levels of ambient PM10 increases the risk of preterm birth. Our study also suggests that the risk may vary by clinical subtypes of preterm birth and exposure time windows. Our findings are relevant for health policy makers from China and other regions with high levels of air pollution to facilitate the efforts of reducing air pollution level in order to protect public health., (Copyright © 2014 Elsevier Ltd. All rights reserved.)