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Streptococcus mutans (S. mutans) is the most common cariogenic bacteria and causes caries by forming biofilms. A novel gradient Cu-bearing titanium alloy (TC4-5Cu/TC4) was manufactured using selective laser melting (SLM) technology for dental applications, which is anticipated to inhibit the formation of biofilm. In this study, the released concentration of copper ions in both minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) was tested in order to assess the antibacterial property of the alloy against planktonic S. mutans, and the antibacterial and antibiofilm efficiencies of TC4-5Cu/TC4 alloy against sessile S. mutans were evaluated via quantitative antibacterial tests and biofilm determination. Reverse transcription polymerase chain reaction (RT-PCR) was performed to analyze the expression of biofilm-related genes (gtfB, gtfC, gtfD, ftf and gbpB) and acid production-related gene (ldh). The results suggested that the MIC and MBC of Cu2+ were much higher than the release concentration of copper ions of the alloy, which was consistent with the lack of antibacterial effect against planktonic bacteria. On the contrary, TC4-5Cu/TC4 alloy exhibited significant bactericidal property against the sessile bacteria and efficient biofilm-restrained ability, and all genes detected in this research were down-regulated. The results indicated that the TC4-5Cu/TC4 alloy suppressed biofilm formation and the sessile bacterial viability by down-regulating biofilm-related genes.

Inspired by increasing demand of advanced pulsed power capacitors, the development of lead-free dielectric ceramic capacitors with high energy storage density and temperature-insensitive performance are extremely crucial. Herein, the lead-free relaxor ferroelectric ceramics based on (1-x) (Na0.5Bi0.5)0.6Sr0.4TiO3- xSr0.7La0.2ZrO3 [abbreviated as (1-x)NBST-xSLZ] are prepared by the solid-state reaction route. The large recoverable energy density (Wrec) of 3.45 J/cm3 and efficiency (η) of 90.1% are simultaneously realized in 0.86NBST-0.14SLZ ceramic due to increased breakdown strength. Furthermore, both the Wrec and η of 0.86NBST-0.14SLZ ceramic display superior of thermal stability (20–180 °C), frequency stability (1–1000 Hz), and cycle stability (104) within a satisfactory range of variation. In addition, the 0.86NBST-0.14SLZ ceramic can also achieve a large current density (CD) of 625 A/cm2, an ultrahigh power density (PD) of 50 MW/cm3 and a fast discharge rate (τ0.90) of 160.8 ns at 160 kV/cm. These results demonstrate that the 0.86NBST-0.14SLZ ceramic could be a highly competitive and eco-friendly relaxor ferroelectric material for next-generation pulsed power capacitors.

In this work, the +3-valent P-doped SrTiO3 has been shown for the first time to be theoretically achievable and to improve the photocatalytic performance of SrTiO3 in co-doping with metal ions. The effects of P and V doping on the electronic structure, optical properties and photocatalytic activity of the SrTiO3 system were systematically investigated using a first-principles calculation method. The results show that when V is singly doped with SrTiO3, although the band gap width is greatly reduced and the optical absorption performance is significantly enhanced, it is difficult to photocatalytic split water for hydrogen production due to the high VBM. When one electron provided by +3-valent P as a donor is transferred near +5-valent V, the orbital hybridization between V-3d and O-2p will lead to a suitable reduction in the band gap width of SrTiO3. The band edge alignment respect to water redox potentials proves that its band edges match well with the redox potentials of water. It was also found that P and V co-doping could reduce the complexation of photogenerated carriers and create a new optical absorption peak in the visible range. The calculated results imply that the P and V co-doping could improve the visible light photocatalytic activity of perovskite SrTiO3.

In this paper, the ion substitution mechanism of CsPbIBr2 films prepared by a drop-coating method is studied. CsI/CsBr methanol solution is drop-coated on a CsPbIBr2 precursor film to prepare the C...

Photothermal reverse water gas shift (RWGS) catalysis holds promise for efficient conversions of greenhouse gas CO2 and renewable H2, powered solely by sunlight, into CO, an important feedstock for the chemical industry. However, the performance of photothermal RWGS catalysis over existing supported catalysts is limited by the balance between the catalyst loading and dispersity, as well as stability against sintering. Herein, we report a core-shell strategy for the design of photothermal catalysts, by using Ni12P5 as an example, with simultaneously strong light absorption ability, high dispersity and stability. The core-shell structured Ni12P5@SiO2 catalyst with a relatively small Ni12P5 particle size of 15 nm at a high Ni12P5 loading of 30 wt% exhibits improved activity, nearly 100% CO selectivity, and superior stability in photothermal RWGS catalysis, particularly under intense illuminations. Our study clearly reveals the effectiveness of the core-shell strategy in breaking the limitation of supported catalysts and boosting the performance of photothermal CO2 catalysis.

Benzoxazine resin exhibits excellent properties and is widely used in many fields. Herein, the synthesis of a novel compound, the bis(2,4-dihydro-2 H-3-(4- N-maleimido)phenyl-1,3-benzoxazinyl)biphenyl (BMIPBB), has been reported, which was synthesized by reacting N-(4-aminophenyl)maleimide (APMI), formaldehyde, and 4,4’-dihydroxybiphenyl. 1,3,5-three(4-(maleimido)phenyl)-1,3,5-triazine (TMIPT) was formed as an intermediate during the reaction. The proton nuclear magnetic resonance (1H-NMR) and Fourier transform-infrared (FTIR) spectroscopy experiments were conducted to determine the structure of BMIPBB. BMIPBB was obtained as a reddish-brown solid in 40.1% yield. The thermal properties of BMIPBB were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Analysis of the DSC curves revealed that the broad peak representing the release of curing reaction heat appeared in the temperature range of 140–330°C. The peak temperature was 242.59°C and the heat of the reaction was 393.82 J/g, indicating that the rate of the curing reaction was low and the heat of the reaction was high. Analysis of the TGA results revealed that the weight loss rate was 5% at 110°C. The monomer exhibited a significant weight loss in the range of 320–500°C. The compound lost 50% of its weight at a temperature of 427°C.

The mechanical behavior of polyethylene (PE) co-polymerized with polyhedral oligomeric silsesquioxane (POSS) was studied by using molecular simulations. Simulation configurations consisted of aligned PE chains with POSS attached to the central chain and amorphous PE chains with different content POSS. From the simulations with aligned PE chains with POSS, it was found that the method for reinforcement was due to dislocation pile-up at POSS, and above a critical stress the dislocations traverse the POSS causing a sawtooth variation in the load-displacement curve. The stress-strain curves for amorphous PE-POSS bulk showed distinct elastic and plastic straining stages. Plastic straining consisted of hardening and slipping segments attributed to dislocation pile-up and chain sliding. Computational results were used to develop a reinforcement model to describe the mechanical response of PE-POSS bulk under uniaxial tension.

The Ti-based metal-organic framework (Ti-MOF) MIL-125 with tunable crystalline size in the range of ca. 50 nm to 1500 nm was synthesized by the coordination modulation method using trans-cinnamic acid (CA) as a modulator. The coordination modulation also induced hierarchical porosity and structure defects on the nanocrystals. A significant size-dependent catalytic activity towards the oxidative desulfurization (ODS) reaction was observed for these MIL-125 nanocrystals. In particular, the MIL-125 nanocrystals with a mean size of ca. 50 nm exhibit dramatically enhanced catalytic performance for the bulky sulfur compound 4,6-dimethyldibenzothiophene (4,6-DMDBT) compared to the microcrystals. It is demonstrated that the size modulation of MIL-125 is an effective approach to promote its performance for the catalysis of bulky molecules.

First-principle calculations, especially by the density functional theory (DFT), is used to study the structure and properties of oxygen/metal interfaces. Adsorption of oxygen molecules or atoms on metal surfaces plays a key role in surface science and technology. This review is dedicated to the adsorption of oxygen molecules or atoms on metal surfaces and diffusion behavior from first-principle investigation. We hope that this review can provide some useful contributions to understand the study of adsorption properties and diffusion behavior on a metal surface at an atomic-scale, especially for those interested in catalytic oxidation and application of corrosion.

Biochar was prepared by dry torrefaction of wood meal in a batch reactor under pressurized conditions. The biochar prepared at 340 °C (WMB-340) showed a higher heating value (HHV) of 30.5 MJ/kg, and it was employed to co-combust with anthracite coal (AC) with the HHV of 28 MJ/kg. The WMB-340 underwent two combustion stages, while the AC only showed one combustion stage. The combustion of AC was promoted by WMB-340 at temperatures higher than 490 °C, indicating the existence of a synergetic effect during co-combustion. Blending AC with 10% WMB-340 had no obvious effect on the combustion stage of AC. However, three combustion stages existed when blending more than 10% WMB-340 with AC. The activation energy of AC blended with 10% WMB-340 was 84.5 kJ mol-1, much lower than that of AC (179.3 kJ mol-1), indicating a lower energy for initialization of the blend. Therefore, AC blended with 10% WMB-340 was the optimal ratio for co-combustion in this study.

Lithium–sulfur (Li–S) batteries are clean energy conversion devices with high theoretical energy densities and specific capacities. However, Li–S batteries exhibit poor cycling stability during the...

Excellent thermal insulating materials are highly demanded in various applications including buildings, aerospace and sport equipment. However, in practical applications, the performance of thermal insulating materials usually deteriorates under diverse temperature and humidity conditions. Therefore, it is highly essential to construct a bulk material that exhibits outstanding thermal insulation performance under extremely humid and hot environment. In this work, we have conceived a green and effective strategy to fabricate a superhydrophobic and compressible polyvinylidene fluoride/polyimide (PVDF/PI) nanofiber composite aerogel via electrospinning and freeze-drying technique. Interestingly, the PVDF nanofibers and PI nanofibers function as the hydrophobic fibrous framework and mechanical support skeleton, respectively, forming a robust three-dimensional framework with good mechanical flexibility. The PVDF/PI aerogel possesses outstanding superhydrophobic feature (water contact angle of 152°) and low thermal conductivity (31.0 mW m−1 K−1) at room temperature. Significantly, even at 100% relative humidity (80°C), the PVDF/PI aerogel still exhibits a low thermal conductivity of only 48.6 mW m−1 K−1, which outperforms the majority of commercial thermal insulating materials. Therefore, the novel PVDF/PI aerogel is promising as an excellent thermal insulating material for the applications in high-temperature and humid environment.

In this study, the effect of Y2O3 addition on the quality, microstructure, and microhardness of multi-track laser-cladded Ti-6Al-4V coating using coaxial powder feeding was investigated. These parameters were characterised via dye penetration, x-ray diffractometry, scanning electron microscopy, energy dispersive spectrometry, electron probe microanalysis, microhardness measurements, and ball-on-disc tribometer. It is observed that Y2O3 addition improved the coating quality by completely eliminating the formation of pores in multi-tracked Ti-6Al-4V coatings. The microstructure of the coating without and with Y2O3 primarily consists of acicular martensite (α′-Ti). Furthermore, the continuity of original β-Ti grain boundary is broken by the introduction of Y2O3. In addition, the Y2O3 is adsorbed and pinned at the original β-Ti grain boundaries resulting in the refinement of the β-Ti grains. It is believed that the refinement in the original β-Ti grains occurs via inhibition of the movement of the grain solid–liquid interface through dragging action. This phenomenon hinders grain growth by acting as a heterogeneous nucleus rather than increasing nucleation rate because it exhibits high lattice misfit degree. Compared with the coating without the Y2O3, the microhardness and wear stability of the Y2O3-supplemented coating was improved because of grain boundary strengthening, fine-grained strengthening, addition of high hardness Y2O3, and elimination of pores.

The fatigue crack growth behavior of medium-density polyethylene (MDPE) under constant amplitude load was experimented on plate specimens. The effect of additional imposed single overload was also researched. An optimized crack front marking method was developed to obtain the actual crack front shape of polymer materials in fatigue crack growth, which was successfully applied to the studied MDPE. The results showed that the retardation of fatigue crack growth evidently appeared after the tensile overload was applied, which was similar to metallic materials. The passivation of the wedge-shaped plastic zone was a primary cause to crack retardation. The theory based on residual stress was introduced to describe the retardation effect, and the plastic zone size of crack tip was calculated by the Dugdale model. The Wheeler model was successfully used to fit the decreased crack growth rate.

The performances of electron-transport-layer (ETL)-free perovskite solar cells (PSCs) are still inferior to ETL-containing devices. This is mainly due to severe interfacial charge recombination occurring at the transparent conducting oxide (TCO)/perovskite interface, where the photo-injected electrons in the TCO can travel back to recombine with holes in the perovskite layer. Herein, we demonstrate for the first time that a non-annealed, insulating, amorphous metal oxyhydroxide, atomic-scale thin interlayer (ca. 3 nm) between the TCO and perovskite facilitates electron tunneling and suppresses the interfacial charge recombination. This largely reduced the interfacial charge recombination loss and achieved a record efficiency of 21.1 % forn-i-pstructured ETL-free PSCs, outperforming their ETL-containing metal oxide counterparts (18.7 %), as well as narrowing the efficiency gap with high-efficiency PSCs employing highly crystalline TiO(2)ETLs.

Electrospun poly(vinylidene fluoride) (PVDF) nanofiber web has been widely utilized as a functional material in various flexible sensors and generators due to its high piezoelectricity, ease processability, and low cost. Among all the crystalline phases of PVDF, β-phase is a key property for PVDF nanofiber web, because the content of β-phase is directly proportional to piezoelectric performance of PVDF nanofiber web. Herein, the impact of graphene content (GC), tip-to-collector distance (TCD), and rotational speed of collector (RSC), as well as their interactions on the β-phase formation of PVDF nanofiber web is systematically investigated via design of experimental method. The fraction of each crystalline phase of PVDF nanofiber web is calculated by FTIR spectra, and the crystallinity is determined by XRD patterns. The influences of GC, TCD, and RSC on both β-phase fraction and crystallinity of PVDF nanofiber are analyzed using Minitab program. The results show that GC, TCD, and RSC all have significant effect on the β-phase content of PVDF nanofiber web, and GC is the most significant one. In addition, an optimal electrospinning condition (GC = 1 wt%, TCD = 4 cm, and RSC = 2000 r·min–1) to fabricate high β-phase crystallinity of PVDF nanofiber web is drawn, under which the crystallinity can reach 41.7%. The contributions in this study could provide guidance for future research on fabricating high performance PVDF nanofiber web based sensors or generators.

Cenospheres are the main component of industrial waste of fly ash and taking full advantage of them has good economic and environmental values. In this paper, cenospheres sensitized emulsion explos...

In order to obtain the effect of second phases on Charpy impact energy and crack propagation behavior of Hastelloy N sheet, Charpy notched impact toughness test have been accomplished with different directions (RD, ND) of V-notch after solution treatment. The fracture morphology and microstructure are observed by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). It is shown that the dominant second phases in Hastelloy N after solution treatment includes molybdenum-riched Ni-Mo phase, which dissolve some elements such as chromium, silicon and ferrum, and a few carbides. The Charpy impact energy of sample 2# (RD) is 225J, almost twice as much as sample 1# (ND). Based on the reconstruction of morphology and distribution of second phases, the mechanism for effect of second phases on crack propagation behavior is discussed. The islands of second phase particles modify the stress triaxiality state, resulting in the propagation path of crack in 2# is totally different from that in 1#.

Nanostructured forms of stoichiometric In2O3 are proving to be efficacious catalysts for the gas-phase hydrogenation of CO2. These conversions can be facilitated using either heat or light; however, until now, the limited optical absorption intensity evidenced by the pale-yellow color of In2O3 has prevented the use of both together. To take advantage of the heat and light content of solar energy, it would be advantageous to make indium oxide black. Herein, we present a synthetic route to tune the color of In2O3 to pitch black by controlling its degree of non-stoichiometry. Black indium oxide comprises amorphous non-stoichiometric domains of In2O3-x on a core of crystalline stoichiometric In2O3, and has 100% selectivity towards the hydrogenation of CO2 to CO with a turnover frequency of 2.44 s−1., The utilization of white-colored, wide-bandgap CO2 hydrogenation photocatalysts has been hindered by their limited light-harvesting ability. By making stoichiometric white indium oxide non-stoichiometric and black, it is transformed from a highly inactive to a highly active photothermal catalyst.

The principle and design of high-resolution sensors are of great significance in the development of fiber-optic sensors. In this article, a general method based on intracavity sensing of fiber ring laser (FRL) is proposed for high-resolution measurement, and a high-resolution temperature sensing system is experimentally demonstrated. The theoretical model for intracavity sensing of FRL is presented. In the sensing system, a fiber-optic Sagnac loop is inserted into an FRL for temperature measurement, which performs as the filter and sensing head simultaneously. Because the filter characteristics of the Sagnac loop is modulated by temperature, the intracavity intensity-modulated sensing is induced for the output power of the FRL. With the method based on intracavity sensing, the temperature resolution level of the sensing system has been improved from 10−3 °C–10−6 °C. The stability and measurement errors are also measured. The proposed method can be extensible to similar fiber-optic sensors to improve measurement resolution.

The effects of rare-earth yttrium (Y) element on the microstructure, mechanical properties and corrosion properties of 20Cr13 martensitic stainless steel were investigated by optical microscopy, scanning electron microscopy and tensile test. Electrochemical experiments were carried out to study the effect of rare-earth element Y addition on corrosion resistance. The results showed that the addition of 0.02 wt.% rare-earth yttrium to martensitic stainless steel could affect the microstructure transformation, and Ac3 temperature was obviously increased. In the stainless steel after heat treatment, there were more pro-eutectoid ferrite in the steel with 0.02 wt.% yttrium. The mechanical test results showed that the addition of 0.02 wt.% yttrium could significantly improve the tensile strength and elongation of the steel, which was related to the influence of yttrium element on inclusions in the test steel. With the quenching temperature of 0.02 wt.% yttrium steel increasing, the content of the ferrite in steel was affected and the corrosion resistance was remarkably improved.

Energetic hollow microcapsules (EHMs) were designed as dual-functional sensitizers for emulsion explosive with pentane/TiH2 and poly(methyl methacrylate) (PMMA) as core and shell, respectively. SEM...

The photocatalytic reduction of CO2 into chemical fuels is one of the most important artificial photosynthesis processes, which can simulate the natural photosynthesis in green plants, and it will be a crucial procedure in the carbon neutral economy. In the current study, we report that inorganic CsPbBr3 perovskite submicron single crystals can exhibit photocatalytic reduction of CO2 directly on their surface with high stability and selectivity in several nonaqueous solvents. The solvent effects have been well studied, which finally leads to an approximately 25-fold enhancement in the photocatalytic reaction rate by substituting toluene with ethyl acetate. The loading of a Pt co-catalyst via a photochemical deposition process further doubled the electron yield rate, which finally reached 5.6 μmol g−1 h−1, thereby implying that the optimization of the reaction media and surface catalytic activity are of key importance for the superior photocatalytic performance of halide perovskite materials.

In this paper, an experimental study on the near detonation limits for propane-hydrogen-oxygen is performed. Three mixtures (i.e., 8H2–C3H8–9O2, 4H2–C3H8–7O2 and 12H2–C3H8–11O2) are tested in a rectangular tube (52 mm × 32 mm). Photodiodes with regular intervals are mounted on the tube wall to measure the time of arrival of detonation waves, from which the detonation velocity is determined. Smoked foils are inserted into the tube to obtain the detonation cell pattern. The results indicate that well within the detonation limits, the detonation can propagate at a steady velocity. By reducing the initial pressure, the detonation velocity decreases gradually. Subsequently, the detonation fails as the initial pressure is below a critical pressure. The critical pressures for 8H2–C3H8–9O2, 4H2–C3H8–7O2 and 12H2–C3H8–11O2 mixtures are 4 kPa, 5 kPa and 6 kPa, and the corresponding detonation velocity deficits are 10%, 9%, 10%, respectively. The cellular detonation structures show that the cell size decreases with the decrease of the hydrogen concentration, and the cell structures are very irregular near the detonation limits.

This paper proposes a nonlinear electromagnetic-thermal-velocity coupling model to study the insulation performance of converter transformer, in which the saddle-like electric-stress dependence is considered under compound alternating current-direct current (AC-DC) voltage situation. Firstly, the conductance of transformer oil and oil-immersed pressboard have been measured through constructed three-electrode experimental system. An interesting electric-stress characteristic, which is saddle-like electric-stress dependence is obtained and counted in the thermal-insulation analysis in the proposed model. Then, the high-order harmonics of compound AC-DC voltage have been considered in the built electromagnetic-thermal-velocity coupling model. Additionally, the impact of non-uniform temperature result has been mapped to the electric field domain through interpolation method, due to different meshes between the flow-thermal and electric fields in accordance with distinct computational characteristics. Finally, the performance of nonlinear thermal-electric coupling properties, including saddle-like electric-stress dependence, have been considered in the proposed coupling model. Results determine that saddle-like thermal-electric dependent properties would considerably change insulation capability, compared with results from the traditional method. Even intensity field of some sampling points could jump more than 1.6 kV/mm. Therefore, it is essential to evaluate the insulation design by practical saddle-like electric-dependent properties.

Tailoring the performance of a photocatalyst by design is challenge in the field of renewable synthetic fuels. Herein, polymorphic heterostructures comprised of two indium oxide based photocatalysts, with distinct structures yet continuously adjustable fractions of the same composition, enable optimization of the activity and selectivity of CO2 hydrogenation to CO and CH3OH. The strategy rests on the cubic (c-) to rhombohedral (rh-) indium oxide hydroxide In2O3−x(OH)y phase transition, in which the fraction of the cubic phase that nucleates and grows within the rhombohedral phase is under precise structural and compositional control. Interfaces so-formed between cubic and rhombohedral polymorphs with distinct electronic band structures as well as separate locations of electron trapping oxygen vacancies and hole trapping hydroxyl defects in individual In2O3−x(OH)y components, enable charge generation, separation and lifetimes of photogenerated electron–hole pairs to be finely tuned. This facilitates command over H2 and CO2 surface chemical reactions that are responsible for the activity and selectivity towards products CO and CH3OH. The control over the performance metrics of a CO2 hydrogenation photocatalyst provided by tuneable rh/c-In2O3−x(OH)y polymorphic heterostructures, affords promising opportunities for the future development of renewable synthetic fuels.

The study of natural gas accumulation process in tight formation has become the focus of the petroleum industry. One of the priorities is the effects of interactions in natural gas/water/rock system on hydrocarbon migration and accumulation process. On the macroscopic scale, we investigate the interactions in natural gas/water/rock system by formation fluorescence test and production data analysis. One the microscopic scale, the mechanisms are revealed by mathematical analysis and experimental methods considering the variation of geological temperature and pressure. The effects of interactions in natural gas/water/rock system are also simulated by numerical simulation. The results are visualized and quantified. A novel semi-analytical method based on a physical experiment is proposed to calculate the temperature- and pressure-dependent contact angle and interface tension which reflect the interactions in the natural gas–water–rock system. This semi-analytical is embedded in the numerical simulation during the simulation of the natural gas charging process. The results indicate that with the increase of geological temperature and pressure, the contact angle will increase and the interface tension between natural gas and water will decrease. The capillary resistance in the formation will be reduced. Since the decrease of capillary resistance, the natural gas can be charged into smaller pores, so that the actual charging threshold is lower than the one originally obtained under present reservoir conditions. After considering the temperature and pressure during the accumulation process, some sand bodies that were thought not to be charged may have natural gas accumulate.

The ZnO/Ni2S3 composite has been designed and in situ synthesized on Ni foam substrate by two steps of electrodeposition. ZnO was achieved on Ni foam by a traditional potentiostatic deposition, followed by cyclic voltammetric (CV) electrodeposition, to generate Ni2S3, where the introduction of ZnO provides abundant active sites for the subsequent Ni2S3 electrodeposition. The amount of deposit during CV electrodeposition can be adjusted by setting the number of sweep segment and scan rate, and the electrochemical characteristics of the products can be readily optimized. The synergistic effect between the ZnO as backbones and the deposited Ni2S3 as the shell enhances the electrochemical properties of the sample significantly, including a highly specific capacitance of 2.19 F cm−2 at 2 mA cm−2, good coulombic efficiency of 98%, and long-term cyclic stability at 82.35% (4000 cycles).

Efficient and economical separation of 1,3-butadiene (C4H6) from C4 hydrocarbons is imperative yet challenging in industrial separation processes. Herein, a guest-induced flexible Mn-bpdc MOF has been employed to separate C4H6 from C4 hydrocarbons, including n-butene (n-C4H8), iso-butene (iso-C4H8), n-butane (n-C4H10) and iso-butane (iso-C4H10). Significantly, C4H6 can instantaneously induce gate-opening of Mn-bpdc MOF at 0.13 bar and 298 K, thus significant amounts of C4H6 can be adsorbed, while other C4 hydrocarbons cannot induce the gate-opening even at 1 bar. The uptake selectivities of Mn-bpdc MOF for C4H6/n-C4H8 and C4H6/iso-C4H8 are up to 40.0 and 45.0 at 298 K and 1 bar, respectively, both surpassing all the reported adsorbents. In addition, breakthrough experiments verified that C4H6/n-C4H8, C4H6/iso-C4H8, C4H6/n-C4H10 and C4H6/iso-C4H10 mixture can be efficiently separated. More importantly, Mn-bpdc possesses excellent water stability and outstanding regeneration ability for C4H6 separation, making it a new benchmark for C4H6 purification.

Endovascular repair of the thoracic aorta with self-expanding stent-grafts has been emerging as a less invasive alternative treatment compared with conventional open surgeries. Despite the promising efficacy and safety of endovascular stent grafting, the stent-graft failure remains a major concern in terms of stent migration, device fatigue, and the risk of endoleaks. Challenges associated with the stent-grafts involve optimized geometrical structure, lifetime fatigue resistance, and adequate radial support. In this work, a novel endovascular stent-graft system is developed specially for the treatment of Stanford type B thoracic aortic dissections (TAD). Numerical study with finite element analysis (FEA) was utilized to evaluate the mechanical behaviors of the individual stent component. Results of the simulation were validated by experimental tests. Based on the systematic analysis of the parametric variations, a final stent-graft system was developed by the selection and arrangement of the individual stent components, targeting an optimal performance for treatment of TAD. The optimized solution of the stent-graft system was tested in clinical trials, showing advantageous therapeutic efficacy.

The effects of (NH4)2SO4 concentration (c((NH4)2SO4)) on hydrogen evolution and Mn electrodeposition on stainless steel (SS) in different potential ranges were investigated by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), potentiostatic polarization, chronoamperometry, scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques. The results show that the NH4+ discharge reaction (NDR) intensifies the overall hydrogen evolution kinetics, and the NDR is catalyzed by increasing c((NH4)2SO4) and over-potential. The electro-crystallization of Mn on SS follows a three-dimensional progressive nucleation and diffusion-limited growth mechanism. Increasing the over-potential could accelerate the nucleation rate and also cause the decline of the nucleation density. The absorbed Mn2+ preferably discharges at low over-potential. Increasing c((NH4)2SO4) at medium over-potential could improve the current efficiency and produce more block-like grains. The nucleation process is suppressed by increasing c((NH4)2SO4) at high over-potential, at which the formation of columnar grains with higher hydrogen contents becomes prevailing.

Adopting effective strategies to control the solidification structure of Ni-based superalloys is a very interesting subject for metallurgists. Despite the achievement of developing and applying the continuous unidirectional solidification process in simple alloys, the utilization of this process for K418 alloys has been ignored. The microstructure and mechanical properties of a K418 alloy ingot produced by the continuous unidirectional solidification process were investigated. We found that the γ dendrites were typically cross-shaped in the transverse section. The orientation of surviving grains along the casting direction was during competitive growth. The secondary dendrite arm spacing was 32.3 ± 2.5 μm at a cooling rate of 1.75 ± 0.35 °C/s from the surface to the center of the K418 alloy ingot. Due to the higher cooling rate than that of the conventional casting process, a more uniform microstructure and finer γ′ precipitation were obtained in the ingot. Thus, compared with the conventional casting, the tensile strength and the elongation are increased by 8.4 and 21.3%, respectively, at 25 °C. The tensile strength and elongation increased by 15.2 and 49.3%, respectively, at 800 °C. In addition, the fracture surfaces exhibited numerous typical dimples and dendritic fracture characteristics.

In order to investigate the effects of the specific heat, thermal conductivity and heat of pyrolysis reaction on the temperature distribution and temperature variation of a single printed circuit board (PCB) particle during the pyrolysis process, a mathematical model is established and the heat transfer process is simulated. The results show that the effects of the specific heat on the temperature distribution and temperature variation are different for different parts of the PCB particle. The effect on the center part is very obvious. The biggest temperature deviation is 12% when considering and ignoring the variation of specific heat with temperature. The anisotropy of the thermal conductivity has a certain impact on the variation of the temperature. The PCB particle begins to decompose at about 300 °C. The pyrolysis reaction needs to absorb much heat to break the chemical bonds, which will delay the temperature rise. In addition, the thermogravimetric (TG) experiment is carried out to verify the rationality of the model. By comparing the TG and differential thermogravimetric (DTG) curves between the experiment and the simulation, there is a 9.08% difference at the final pyrolysis temperature between the two mass losses, which means the mathematical model is reasonable.

Although great advancements have been successfully achieved in ligand-assisted reprecipitation strategy (LARP) towards lead halide perovskite nanocrystals (NCs) synthesis, it still remains challenging to develop bright and stable iodide-based perovskite NC via facile LARP. Herein, strikingly bright MAPbI3 NCs with photoluminescence quantum yield (PLQY) as high as 79% are synthesized via replacing the raw material (MAI and PbI2) with MAPbI3 crystal powder during LARP procedure. It has been found that crystal powder derived MAPbI3 NCs are more iodide-rich compared with that based on raw material, which is favorable to passivate the surface trap state. Accordingly, femtosecond transient absorption spectroscopies and space charge limited current measurements have corroborated that the trap density is much less in crystal powder resulted MAPbI3 NCs. Further analyses indicate stronger solvation with reduced precursor colloid size has been observed in crystal powder derived precursor solution probably due to the formation of MAPbI3·DMF. This work has provided a facile but valid method to enhance the photoluminescence of perovskite NC via modulating the beginning precursor solution.

Recent years have witnessed an explosive interest in branched TiO2 nanostructures (BTNs) due to their promising applications in a wide range of energy-related fields. As anode materials for solar cells (dye- or quantum dot-sensitized solar cells and perovskite solar cells), photoelectrochemical synthetic cells and energy storage devices (e.g., Li-ion batteries), BTNs with inherent nature of structural hierarchy and porosity, provide fascinating optical, electrical and electrochemical properties such as high surface area, superior light scattering and confinement, and fast electron transport. This review summarizes the recent advances in the preparation of BTNs with tailored host-guest morphologies, branches compositions and structural complexity. Their promising progress achieved in the field of energy conversion and storage is discussed. Two blossoming representatives, including the tree-like branched TiO2 nanoarrays and urchin-like branched TiO2 spheres, are highlighted to shed light on the effect of smart surface branched modification on improving the solar-to-electricity or solar-to-fuel conversion efficiencies, and increasing energy (power) densities. In addition, we also provide perspective on the new trend and future directions of novel multifunctional BTNs for next-generation energy conversion and storage devices.

As a unique kind of artificial periodic composite materials, phononic crystals have attracted the wide attention in recent years. Unremitting efforts have been made to investigate the potential existence of phononic bandgaps, which can be used to manipulate the propagation of acoustic/elastic waves. This paper proposes a new topology optimization algorithm to achieve the optimised bandgap structures of 3D phononic crystals based on fixed-grid finite element method (FEM) and evolutionary procedure. The maximum normalised gap ratio obtained is as large as 97% between the 12th and 13th order of bands, with the optimised structure of tungsten carbide spheres embraced in epoxy matrix. Symmetric unit cells for simple cubic (SC) lattice are presented for the specified bandgaps to validate the effectiveness of the proposed optimization algorithm for designing 3D phononic bandgap crystals. Meanwhile, the proposed topology optimization represents structures with clear topologies and smooth boundaries.

Low initial strength, slow strength increase, slow curing, high temperature susceptibility, poor water damage resistance, and poor storage stability are the major shortcomings of traditional cold mix asphalt (CMA). Unlike the traditional CMA, reactive liquid asphalt (RLA) was produced to overcome the weaknesses in this study. Its optimal ingredient mix, which includes silane coupling agents (SCA), asphalt modifiers, reactive solvents (RS), and curing agents (CA) was determined according to the single factor and orthogonal experimental results in the laboratory. The performance of the resulting RLA was systematically evaluated. The fundamental properties proved favorable, which were characterized by penetration of 5 mm, ductility of 49 cm and softening point of 70 °C, the dynamical shear rheology (DSR) and bending beam rheology (BBR) results showed that its performance grading could reach PG70-22, indicating satisfactory for most regions in the world. The adhesion between RLA and coarse aggregate results suggested that the stripping risk was significantly reduced. In addition, the satisfied compatibility and performance of RLA were revealed by analyzing scanning electron microscopy (SEM) and infrared spectral analysis (IR) results.

The viscoelasticity of constituent materials has a significant effect on the dispersion relation of waves in viscoelastic phononic crystals (PCs). This paper extends the bi-directional evolutionary structure optimization (BESO) method to the design of viscoelastic PCs with the maximum attenuation and stiffness. The attenuation factor is calculated by the k(ω)-method, and the effective elasticity matrix of composite PCs is extracted by the homogenization theory. The inverse design of viscoelastic PCs is formulated with a topology optimization problem, which is then solved by the proposed BESO method. Generally, BESO re-distributes the material phases of viscoelastic PCs within the primitive unit cell step by step based on sensitivity analysis. The optimization process is stopped until the optimized viscoelastic PC with the maximum attenuation factor and the desirable bulk modulus is achieved. Numerical examples are systematically presented for the propagation of out-of-plane or in-plane waves, and combined out-of-plane and in-plane waves at various frequencies. Novel topological patterns of the optimized viscoelastic PCs are obtained and discussed.

A novel energetic microsphere with multicore hollow structure and uniform particle size is prepared by an improved suspension polymerization-thermal expansion method with methyl methacrylate, azodicarbonamide (AC) and TiH2 powder as monomer, blowing agent and core material, respectively. The energetic hollow microspheres (EHMs) can play double roles as sensitizers and energetic additives in emulsion explosive, and experimental results show that the EHMs could increase the power of emulsion explosive without affecting its safety. This method provides a completely new idea for the development of high energy emulsion explosive.

To investigate unsteady interaction mechanism between the rim seal flow in turbine stator-rotor cavity and main flow, detailed unsteady numerical simulations of the flow field and unsteady characteristic of the vane were conducted under different rim seal mass flow rate. The results show the blockage effect resulting from the egress flow leads to the pressure to increase and static entropy to reduce on the latter half of suction side near the hub. From the case without a cavity to RI=1.7%, at 5% span, the maximum pressure coefficient increase on the suction side reaches 6%. Moreover, the blockage effect causes the velocity to decrease at vane exit. Furthermore, the rim seal flow results in the decrease in lateral pressure gradient, causing the strength of hub passage vortex and hub trailing shedding vortex to reduce. Without rim seal flow, the ingress flow contributes to decreasing unsteady fluctuation from the hub to 10% span. When there is rim seal flow, unsteady fluctuation continues to reduce due to coupling effects of the egress flow from the ingress and the egress flow form the cavity inlet.