Aluminum/polytetrafluoroethylene (Al/PTFE) is a revolutionary type of impact initiation materials, and is extensively utilized in military and civilian applications. In this research, three types of additives (W, Fe and TiH2 particles) were added into Al/PTFE, and their effects on the compressive strength and impacting reactive characteristics were investigated. The addition of W particles into Al/PTFE had the highest mechanical strengthening effect compared to the other two types of additives. The compressive strength reached 178.7 MPa, 169.2 MPa and 154.7 MPa under the strain rate of 3000 s−1 of Al/PTFE/W, Al/PTFE/Fe and Al/PTFE/TiH2 specimens, increased by 54.6%, 46.4% and 33.8% compared to Al/PTFE (115.6 MPa), respectively. The formation of elastic PTFE nano-fibers inhibited the extension of micro-cracks was the main strengthening mechanism. The composites reacted violently under high-speed impacts, and the energy release efficiency was quantitatively calculated. Al/PTFE/TiH2 specimen had the highest reaction heat and energy release efficiency (8.15%) compared to the other three types of composites. Addition of Fe powder into Al/PTFE decreased the impact sensitivity but slightly increased the reaction intensity. However, the addition of W decreased both impact sensitivity and reactivity. The impact reaction proceeded in a mechano-chemical manner, and the reactivity arose from multiple factors.
Traffic accidents involving pedestrians and drivers pose significant public health and safety concerns. Understanding the differential influences of road physical design attributes on crash frequencies for these two groups is critical for developing targeted safety interventions. Considering that the zero-truncated characteristic of the data is uncertain, the results of the zero-truncated negative binomial models and traditional negative binomial models are calculated to seek the better model. The result revealed that the road surface conditions and vertical and horizontal curvature have greater influence on both pedestrian and driver compared to number of lanes and speed limit. And speed limits were more pronounced for pedestrian crash frequency than driver group. Conversely, the effect of different types of intersections was stronger for driver crash frequency. The differential influences of road physical design attributes on traffic crash frequencies for pedestrians versus drivers highlight the importance of adopting a user-centric approach to transportation safety planning and infrastructure design. Tailoring interventions to address the unique needs and vulnerabilities of different road user groups can lead to more effective safety improvements and better overall traffic safety outcomes.
Coal waste (CW) could be used for soil stabilization due to the pozzolanic elements it contains. There hasn’t been much investigation into how different fibers affect the mechanical qualities of stabilized sand, although adding fibers of any kind to soils may improve the soil because of fiber characteristics like rigidity. For this reason, several tests were carried out on sand that contained 6% cement (by dry weight of used sand), 5 wt% CW, 0, 0.25 wt%, and 0.50 wt% fiber, as well as the unconfined compressive strength (UCS) test, indirect tensile strength (ITS) test, unconsolidated undrained triaxial test (UU), scanning electron microscope (SEM) test and ultrasonic pulse velocity (UPV) test. The results showed that in comparison to other fiber reinforced mix designs, the specimen reinforced with 0.5% fibers and the mix design of 0.25 wt% glass and 0.25 wt% polypropylene (PP) fibers exhibited the maximum strength. Examining the impact of fiber type found that glass fibers influence PP strength more favorably than other fiber types. The use of PP fibers is an excellent solution for the problem of large strains in design processes, while adding glass fibers is considered a suitable treatment for issues related to small strains.
Narrow backfill earth pressure estimation is applied to study the stability of supporting structures in the vicinity of existing buildings. Previous narrow backfill earth pressure studies have neglected seismic-unsaturated seepage multi-field coupling, resulting in inaccurate estimates. To address these deficiencies, this paper proposed a calculation method for seismic passive earth pressure in unsaturated narrow backfill, based on inclined thin-layer units. It considers the interlayer shear stress, arching effect, and the multi-field coupling of seismic-unsaturated seepage. Additionally, this paper includes a parametric sensitivity analysis. The outcomes indicate that the earthquake passive ground pressure of unsaturated narrow backfill can be reduced by increasing the aspect ratio, seismic acceleration coefficient, and unsaturation parameter α. It can also be reduced by decreasing the effective interior friction angle, soil cohesion, wallearth friction angle, and vertical discharge. Furthermore, for any width soil, lowering the elevation of the action point of passive thrust can be attained by raising the effective interior friction angle, wall-earth friction angle, and unsaturation parameter α. Reducing soil cohesion, seismic acceleration coefficient, and vertical discharge can also lower the height of the application point of passive thrust.
Cold-rolling was conducted on AZ31 magnesium alloy with fine and coarse grains to produce plates with high density of shear bands and
A pre-reduction sintering process with flue gas recirculation (PSPfsg-FGR) was developed to mitigate alkalis harm to the blast furnace and reduce the flue gas emission in the whole ironmaking process. The results indicated that the pre-reduction sintering process (PSP) can effectively remove 58.02% of K and 30.68% of Na from raw mixtures and improve yield and tumbler index to 74.40% and 68.69%, respectively. Moreover, PSP was conducive to reducing NO x and SO2 emissions and simultaneously increasing CO content in flue gas. Circulating CO-containing flue gas to sintering bed effectively recycled CO and further improved K and Na removal ratio to 74.11% and 32.92%, respectively. Microstructural analysis revealed that the pre-reduced sinter mainly consisted of magnetite, wustite and a small quantity of metallic iron, and very few silicate glass phase was also formed. This process can simultaneously realize alkali metal elements removal as well as flue gas emission reduction from the integrated ironmaking process.
Selective laser melting (SLM) is a cost-effective 3D metal additive manufacturing (AM) process. However, AM 316L SS has different surface and microstructure properties as compared to conventional ones. Boriding process is one of the ways to modify and increase the surface properties. The aim of this study is to predict and understand the growth kinetic of iron boride layers on AM 316L SS. In this study, for the first time, the growth kinetic mechanism was evaluated for AM 316L SS. Pack boriding was applied at 850, 900 and 950 °C, each for 2, 4 and 6 h. The thickness of the boride layers ranged from (1.8±0.3) µm to (27.7±2.2) µm. A diffusion model based on error function solutions in Fick’s second law was proposed to quantitatively predict and elucidate the growth rate of FeB and Fe2B phase layers. The activation energy (Q) values for boron diffusion in FeB layer, Fe2B layer, and dual FeB+Fe2B layer were found to be 256.56, 161.61 and 209.014 kJ/mol, respectively, which was higher than the conventional 316L SS. The findings might provide and open new directions and approaches for applications of additively manufactured steels.
Limited charge carrier lifetime (τ) leads to the short charge carrier diffusion length (L D) and thus impedes the improvement of power conversion efficiencies (PCEs) of organic solar cells (OSCs). Herein, anthracene (AN) as the additive is introduced into classical donor: acceptor pairs to increase the τ. Introducing AN efficiently enhances the crystallinity of the PM6:BTP-eC9+ blend film to reduce the trap density and increase the τ to 1.48 µs, achieving the prolonged L D. The prolonged L D enables the PM6:BTP-eC9+ blend film to gain weaker charge carrier recombination, reduced leakage current, and shorter charge carrier extraction time in devices, compared with PM6: BTP-eC9 counterparts. Therefore, PM6:BTP-eC9+ based OSCs achieve higher PCEs of 18.41%±0.16% than PM6:BTP-eC9 based ones (17.08%±0.11%). Moreover, the PM6:L8-BO+ based OSC presents an impressive PCE of 19.14%. It demonstrates that introducing AN is an efficient method to increase the τ for prolonged L D, boosting PCEs of OSCs.
In this study, Schwertmannite, Akaganéite and Ammoniojarosite were biosynthesized by different bacteria and characterized. Our results showed that bacteria are critical in mediating the mineral formation process: the morphology, crystallinity, grain size and specific surface area of each mineral varied upon different bacteria and culturing conditions. In addition, the formed minerals’ elemental composition and group disparity lead to different morphology, crystallinity and subsequent adsorption performance. In particular, adsorption difference existed in iron minerals biosynthesized by different bacteria. The maximal adsorption capacity of Akaganéite, Schwertmannite and Ammoniojarosite were 26.6 mg/g, 17.5 mg/g and 3.90 mg/g respectively. Our results also suggest that Cr(VI) adsorption on iron-minerals involves hydrogen bonding, electrostatic interaction, and ligand exchange. The adsorption only occurred on the surface of Ammoniojarosite, while for Akaganéite and Schwertmannite, the tunnel structure greatly facilitated the adsorption process and improved adsorption capacity. Thus, we conclude that the molecular structure is the primary determining factor for adsorption performance. Collectively, our results can provide useful information in selecting suitable bacteria for synthesizing heavy-metal scavenging minerals according to different environmental conditions.
Superhydrophobic glass has inspiring development prospects in endoscopes, solar panels and other engineering and medical fields. However, the surface topography required to achieve superhydrophobicity will inevitably affect the surface transparency and limit the application of glass materials. To resolve the contradiction between the surface transparency and the robust superhydrophobicity, an efficient and low-cost laser-chemical surface functionalization process was utilized to fabricate superhydrophobic glass surface. The results show that the air can be effectively trapped in surface micro/nanostructure induced by laser texturing, thus reducing the solid-liquid contact area and interfacial tension. The deposition of hydrophobic carbon-containing groups on the surface can be accelerated by chemical treatment, and the surface energy is significantly reduced. The glass surface exhibits marvelous robust superhydrophobicity with a contact angle of 155.8° and a roll-off angle of 7.2° under the combination of hierarchical micro/nanostructure and low surface energy. Moreover, the surface transparency of the prepared superhydrophobic glass was only 5.42% lower than that of the untreated surface. This superhydrophobic glass with high transparency still maintains excellent superhydrophobicity after durability and stability tests. The facile fabrication of superhydrophobic glass with high transparency and robustness provides a strong reference for further expanding the application value of glass materials.