Cyanogel-Induced Facile Synthesis of Palladium Hydride for Electrocatalytic Oxygen Reduction.

Palladium hydride (PdHx) is one of the well-known electrocatalytic materials, yet its synthesis is still a challenge through an energy-efficient and straightforward method. Herein, we propose a new and facile cyanogel-assisted synthesis strategy for the preparation of PdH0.649 at a mild environment with NaBH4 as the hydrogen source. Unlike traditional inorganic Pd precursors, the unique Pd-CN-Pd bridge in Pdx[Pd(CN)4]y ⋅ aH2O cyanogel offers more favourable spatial sites for insertion of H atoms. The characteristic three-dimensional backbone of cyanogel also acts as a support scaffold resulting in the interconnected network structure of PdH0.649. Due to the incorporation of H atoms and interconnected network structure, the PdH0.649 achieves a high half-wave potential of 0.932 V, a high onset potential of 1.062 V, and a low activation energy, as well as a long-term lifetime for oxygen reduction reaction. Theoretical calculation demonstrates a downshift of the d-band centre of Pd in PdH0.649 owing to the dominant Pd-H incorporation that weakens the binding energies of the *OH intermediate species. Zn-air batteries (ZAB) based on PdH0.649 exhibits high power density, competitive open circuit voltage, and good stability, exceeding that of commercial Pt black. This work not only opens up a new avenue for the development of high-efficiency Pt-free catalysts but also provides an original approach and insight into the synthesis of PdHx.

Low-loaded Ru on hollow SnO2 for enhanced electrocatalytic hydrogen evolution.

In response to the challenges of intermediate poisoning and the high cost of noble metal catalysts in the hydrogen evolution reaction (HER), we develop a Ru-doped SnO2 catalyst. This Ru-SnO2 catalyst has the characteristics of low Ru loading and a hollow structure, which endow it with good electrocatalytic activity and stability for the HER.

Research on the synergistic modification effect and the interface mechanism of GO/SBS compound-modified asphalt based on experiments and molecular simulations.

Although there have been reports showing the modification effect of carbon nanomaterials on asphalt, there are few studies on whether carbon nanomaterials and polymers can have synergistic modification effects on asphalt. At the same time, the complex composition of asphalt makes it difficult to determine the interface mechanism between the modifier and the asphalt. In this study, graphene oxide (GO) and styrene-butadiene-styrene block copolymer (SBS) were selected as modifiers. A combined experimental and molecular simulation research method was used to study the synergistic modification effect and the interface mechanism between the modifier and the asphalt. The results show that the modification effect of GO/SBS incorporated into asphalt is significantly superior to that of GO or SBS incorporated individually and GO/SBS has a synergistic modification effect. Although the binding strength between SBS and asphalt is weak, the GO surface (GO (0 0 1)) can simultaneously bind with SBS and asphalt, increasing the binding strength of SBS and asphalt as well as promoting the dispersion of SBS in asphalt, so that GO/SBS shows a synergistic modification effect and improves properties such as low-temperature ductility, rheology and storage stability at macroscopic level. Intercalated and exfoliated structure can be formed between GO side (GO (0 1 0)) and asphalt, which improves the anti-aging properties of the asphalt. Physical bonding is the main interface binding for GO/SBS compound-modified asphalt. GO bonds to asphalt or SBS by hydrogen bonds and there are only dispersion forces between SBS and asphalt, resulting in a higher binding strength between GO and asphalt or SBS than between SBS and asphalt.

Competitive Adsorption: Reducing the Poisoning Effect of Adsorbed Hydroxyl on Ru Single-Atom Site with SnO2 for Efficient Hydrogen Evolution.

Ruthenium (Ru) has been theoretically considered a viable alkaline hydrogen evolution reaction electrocatalyst due to its fast water dissociation kinetics. However, its strong affinity to the adsorbed hydroxyl (OHad ) blocks the active sites, resulting in unsatisfactory performance during the practical HER process. Here, we first reported a competitive adsorption strategy for the construction of SnO2 nanoparticles doped with Ru single-atoms supported on carbon (Ru SAs-SnO2 /C) via atomic galvanic replacement. SnO2 was introduced to regulate the strong interaction between Ru and OHad by the competitive adsorption of OHad between Ru and SnO2 , which alleviated the poisoning of Ru sites. As a consequence, the Ru SAs-SnO2 /C exhibited a low overpotential at 10 mA cm-2 (10 mV) and a low Tafel slope of 25 mV dec-1 . This approach provides a new avenue to modulate the adsorption strength of active sites and intermediates, which paves the way for the development of highly active electrocatalysts.

Evaluation of the Composite Mechanism of Nano-Fe2O3/Asphalt Based on Molecular Simulation and Experiments.

Asphalt, as an indispensable binder in road paving, plays an important role in transportation development. However, the mechanism of action between the modifier and asphalt cannot be fully explained by the existing test methods. This paper combines molecular simulations with experiments to provide a research and analysis tool to evaluate the "structure-performance" relationship of asphalt. From the trend of experimental results, the optimal content of Nano-Fe2O3 is 1% to 3%. The AFM micrograph of the asphalt material shows that at 3%, the Nano-Fe2O3 can be effectively dispersed in the asphalt and the unique " bee structures " of the asphalt can be adsorbed around the modifier. Molecular dynamics studies and results show that when Nano-Fe2O3 are incorporated into the asphalt and have a strong adsorption force on the colloidal structure of asphalt, the " bee structures " can be adsorbed around the Nano-Fe2O3. In the range of 208-543 K, the sol-gel structure of asphalt in the Nano-Fe2O3/asphalt composite system is gradually disrupted.

Computational and Experimental Insights into the Role of Acidic Molecules on the Corrosion Behavior on 7A46 Aluminum Alloy.

The corrosion mechanisms for different corrosive media on the aged 7A46 aluminum alloy were systematically investigated at nanoscale level. The combination of empirical intergranular and exfoliation corrosion behavior was employed, and coupled with first-principles calculations. Results revealed that the dispersed distribution of matrix precipitates (MPs) leads to the enhancement of the corrosion resistance pre-ageing (PA) followed by double-ageing (PA-DA) alloy. The deepest corrosion depth of PA-DA alloy was in hydrochloric acid, and the calculation result demonstrates that the passivation effect in combination with the accumulation of corrosion products in nitric acid protect the PA-DA alloy from further corrosion.

Research on the Mechanism of Interaction between Styrene-Butadiene-Styrene (SBS) and Asphalt Based on Molecular Vibration Frequency.

Based on the four-component theory of asphalt, molecular models of the saturate, aromatic, resin, and asphaltene were constructed, respectively. The styrene-butadiene-styrene (SBS) polymer was used as the modifier. Using density functional theory (DFT) to study the effect of SBS on the molecular vibration of each component of asphalt, the vibration spectrums and binding energy of the systems composed of SBS and each component molecule of asphalt were calculated. Prepared SBS modified asphalt and measured Fourier transform infrared spectroscopy (FTIR) before and after the experiment. The results show that after SBS was added to asphalt, no chemical reaction occurred, and the system was mainly physical blending. The vibrational peak intensity of SBS and the light components of asphalt (saturate and aromatic) is stronger than that of SBS and the heavy components of asphalt (resin and asphaltene). The interaction strengths of asphalt components and polybutadiene (PB) blocks, polystyrene (PS) blocks of SBS are different. The binding energy of SBS and the saturate is the lowest and the bonding of the system is weakest. The bonding of the systems of SBS and the aromatic, resin, asphaltene is stable, and the stability of these systems are all stronger than that of SBS and the saturate.

Rolling membrane powered by low-temperature steam as a new approach to generate mechanical energy.

How to convert heat energy into other forms of usable energy more efficiently is always crucial for our human society. In traditional heat engines, such as the steam engine and the internal combustion engine, high-grade heat energy can be easily converted into mechanical energy, while a large amount of low-grade heat energy is usually wasted owing to its disadvantage in the temperature level. In this work, for the first time, the generation of mechanical energy from both high- and low-temperature steam is implemented by a hydrophilic polymer membrane. When exposed to water vapor with a temperature ranging from 50 to 100 °C, the membrane repeats rolling from one side to another. In nature, this continuously rolling of membrane is powered by the steam, like a miniaturized "steam engine". The differential concentration of water vapor (steam) on the two sides of the membrane generates the asymmetric swelling, the curve, and the rolling of the membrane. In particular, results suggest that this membrane based "steam engine" can be powered by the steam with a relatively very low temperature of 50 °C, which indicates a new approach to make use of both the high- and low-temperature heat energy.

Multi-Walled Carbon Nanotubes Enhanced the Performance of Epoxy Asphalt Pavement Binder.

Modifying epoxy asphalt with nanomaterials is an effective method to enhance the performance of epoxy asphalt binder. The carbon nanotubes were modified and carbon nanotubes/epoxy asphalt (CNTs-EA) was fabricated by mechanical stirring. The performanceof CNTs-EA pavement binder (CNTs-EAPB) was analyzed by immersion marshall's, freeze-thaw splitting and dynamic stability tests. Experimental results showed that the dynamic stability and freeze-thaw splitting intensity of matrix asphalt binder (MAB) were improved by 118.6% and 85%, respectively. While the dynamic stability of CNTs-EAPB remained 90.8% under soaking water which was more than 77.44% of matrix asphalt and reached 5801 times per mm. This enhancement is mainly attributed to excellent characteristics of CNTs as well as the effective synergistic effect between CNTs and epoxy resin.

Cathepsin C promotes the progression of periapical periodontitis.

Although the role of cathepsin C (Cat C) in inflammation is gradually being elucidated, its function in periapical periodontitis, which is one of the most common infectious diseases worldwide, has not been studied. This study evaluated a surgically-induced model of periapical periodontitis in cathepsin C (Cat C) knock-down (KD) mice, which was constructed with a tetracycline operator, to evaluate the role of Cat C in the pathogenesis and progression of periapical periodontitis. Our results showed, for the first time, that there was a statistically significant increase in the expression of Cat C as periapical periodontitis progressed; this increase started from 1 week after surgery and reached a peak at 3 weeks after surgery, before gradually decreasing. The volume of periapical bone resorption in Cat C KD mice was significantly smaller than that in wild-type mice at 3 and 4 weeks after surgery (P<0.05). Inflammatory cell infiltration into the apical tissues of wild-type mice was also significantly higher than that of Cat C KD mice. The expression of receptor activator of nuclear factor-κB ligand (RANKL) in wild-type mice was also higher than that in Cat C KD mice. The difference in the number of osteoclasts in the apical area between the two groups was statistically significant after 2 weeks. Correlation analysis showed that there was a significant correlation between Cat C and RANKL expression (r= 0.835). Therefore, our data indicated that Cat C promoted the apical inflammation and bone destruction in mice.

A New NLRP3 Inflammasome Inhibitor, Dioscin, Promotes Osteogenesis.

Refractory periapical periodontitis, which is a persistent infection after root canal treatment, still has no effective treatment. Its most common pathogen is Enterococcus faecalis. Here, the precursor of phytosteroids, dioscin, is introduced to fight against the inflammation induced by Enterococcus faecalis. The findings suggest that dioscin inhibits the nuclear transport of NF-κB and the expression of reactive oxygen species (ROS) induced by lipoteichoic acid from the Enterococcus faecalis. The decrease in mRNA and protein levels of NLRP3, Caspase-1, and IL-1ß is observed in dioscin treated mouse macrophages. In the MC3T3-E1 cells, dioscin also promotes the expression of osteogenic-related factors, ALP, Runx2, and OCN. The increased formation of mineralized nodules after the application of dioscin further indicates that dioscin has the potential to promote osteogenesis. The above results suggest dioscin can be a potential root canal irrigation or root canal sealant for the treatment of refractory apical periodontitis.

Free volume, gas permeation, and proton conductivity in MIL-101-SO3H/Nafion composite membranes.

A series of MIL-101-SO3H/Nafion composite membranes was synthesized. They show an improved proton conductivity, due to the abundance of SO3H groups, which fosters proton conduction by binding the water molecules and enabling a larger number of conducting sites. Gas (including water vapor, hydrogen, and oxygen) permeability, crystallinity, and free volumes of the MIL-101-SO3H/Nafion composite membranes were investigated, as well as their correlation. By increasing the MIL-101-SO3H content, the gas permeability of the membranes significantly decreases, since the crystalline region is larger and the water-bearing MIL-101-SO3H particles are efficient barriers for the gas molecules. The gas permeation in the composite membranes is a very complex process and the results indicate no simple linear relation between the gas permeability and the free volume size (VFV), or between the gas permeability and the crystallinity. Moreover, it is very interesting to observe that the influence of VFV on the gas permeability is closely related to the size of the particular gas molecules: the larger the size of the gas molecules, the larger the free volume needed to achieve their rapid diffusion in the membrane. The results suggest the presence of a threshold value for VFV, which depends on the size of the gas molecules: when VFV is lower than this value, the gas molecules cannot easily jump through neighboring free volumes to a neighboring site, and, as a result, the permeability drops quickly.