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 $\{10\bar{1}1\}$ twins, respectively. Then, these two kinds of plates are subjected to isothermal annealing to reveal the effect of shear bands and $\{10\bar{1}1\}$ twins on recrystallization behavior. During annealing, static recrystallization occurs firstly in shear band zones and $\{10\bar{1}1\}$ twin zones, which has different effect on texture and mechanical properties. With the increase of annealing temperature, strong basal texture remains in annealed SG-17% while the basal texture is weakened gradually in annealed LG-15%. Recrystallized grains from twin zones have a random orientation which is responsible for the weakened basal texture in annealed LG-15%. In addition, micro-hardness decreases gradually with the prolonged annealing time due to static recrystallization. LG-15% has a lower recrystallization activation energy because $\{10\bar{1}1\}$ twins are benefit for the nucleation and growth of recrystallization grains. After 500 °C annealing, the yield strength decreases significantly with a significant improvement in failure strain. The annealed LG-15% has a much higher compressive strain than annealed SG-17% due to texture weakening effect.
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.
Ferrite-rich calcium sulfoaluminate (FCSA) cement is often used in special projects such as marine engineering due to its excellent resistance of seawater attack although the cost is a little high. Ground granulated blast furnace slag (GGBS), a byproduct of industrial production, is used as a mineral admixture to reduce concrete costs and provide excellent performance. This study aimed to investigate the impact of GGBS on the hydration properties of FCSA cement in seawater. Tests were conducted on heat of hydration, compressive strength, mass change, and pH value of pore solution of FCSA cement paste with a water-to-binder ratio of 0.45. X-ray diffraction (XRD) analysis and thermogravimetric analysis were used to determine the hydration products, while mercury intrusion porosimetry (MIP) was used to measure pore structure. The results indicated that the FCSA cement hydration showed a concentrated heat release at early age. The compressive strength of specimens consistently increased over time, where seawater curing enhanced the compressive strength of control samples. The pH value of pore solution decreased to 10.7–10.9 at 90 d when cured in seawater. The primary hydration products of FCSA cement included ettringite, iron hydroxide gel (FH3), and aluminum hydroxide gel (AH3). Moreover, when cured in seawater, Friedel’s salt was formed, which enhanced the compressive strength of the specimen and increased its coefficient of corrosion. Seawater curing gradually increased sample mass, and GGBS refined pore structure while reducing harmful pore proportions. These results suggest that while GGBS can refine pore structure and improve certain aspects of performance, its inclusion may also reduce compressive strength, highlighting the need for a balanced approach in its use for marine applications.
It is still challenging for exploring high-active photocatalysts to efficiently remove Levofloxacin (LFX) by activating peroxymonosulfate (PMS). Herein, we constructed a novel Z scheme ZnFe2O4/g-C3N4/CQDs (ZCC) heterojunction by anchoring ZnFe2O4 on tubular-like g-C3N4 induced by CQDs (denoted as CNC) using microwave-assisted thermal methods. The ZCC exhibits the highest photocatalytic activity in activating PMS for LFX degradation, endowing a removal rate ∼95.3%, which is 4.8 and 7.3 times higher than that of pure ZnFe2O4 (19.8%) and g-C3N4 (13.1%), separately. The enhanced photocatalytic activity of ZCC can be attributed to the distinctive morphology of CNC, enhanced light response, increased specific surface area and abundant pore structure. Besides, the formed Z scheme heterojunction and CQDs acting as a transmission bridge of the photogenerated charges (e− and h+) can accelerate transfer and inhibit recombination of e− and h+. Radical capture experiments and electron spin resonance (ESR) measurements revealed that SO4 •− and O2 •− play a predominant role in degradation process of LFX. Liquid chromatography-mass spectrometry (LC-MS) was applied to identify intermediates and propose feasible degradation pathways of LFX. In conclusion, this study presents a promising strategy for regulating the photocatalytic activity of g-C3N4 by simultaneously integrating CQDs induction and Z scheme heterojunction construction.
The significance of breakable particle corners is often overlooked in slope foundation research, resulting in an unclear understanding of the specific behaviors of coastal coral sand slope foundations. Compared with the results in model tests, the discrete element method (DEM) was employed to examine the effect of breakable particle corners on the performance of coral sand slope foundations under a strip footing, from macro to micro scales. The results demonstrate that the bearing characteristics of coral sand slope foundations can be successfully modeled by utilizing breakable corner particles in simulations. The dual effects of interlocking and breakage of corners well explained the specific shallower load transmission and narrower shear stress zones in breakable corner particle slopes. Additionally, the study revealed the significant influence of breakable corners on soil behaviors on slopes. Furthermore, progressive corner breakage within slip bands was successfully identified as the underling mechanism in determining the unique bearing characteristics and the distinct failure patterns of breakable corner particle slopes. This study provides a new perspective to clarify the behaviors of slope foundations composed of breakable corner particle materials.