Search Results (58)

Concrete-filled multi-cell pultruded tubular columns reinforced with lattice-webs (MCPLs) have shown delayed local buckling and a greater confinement effectiveness than concrete-filled pultruded columns (CPCs). However, the anomalous load reduction observed with thicker face sheets highlights the complex influence of fibre layups, while the influence of concrete strength has remained ignored. Therefore, a total of six specimens in three groups were examined in this study to investigate the influence of fibre layup (including pultruded tube thickness and fibre orientation) and concrete strength on the axial compressive behaviour of MCPLs. It was found that all specimens showed a pseudo-ductile behaviour, and the failure modes were significantly affected by the fibre orientations. In addition, MCPLs confirmed a significant confinement, achieving a 76.74% concrete strength enhancement. While improved interface bonding was observed, increasing concrete strength or decreasing tube thickness resulted in lower strength enhancements of 34.65% and 68.60%, respectively. The application of uniaxial hoop fibres improved the confinement effectiveness greatly, showing the highest 81.17% strength enhancement but a lower load-bearing capacity. Furthermore, it was found that the ultimate axial strain of MCPLs was controlled by the related hollow multi-cell composite tubes. Thus, an optimized design-oriented model using the analysis of experimental data was introduced for predicting the compressive behaviour of the filled concrete in MCPLs. The predictions aligned well with the experimental results, offering practical guidance for engineering design. Full article

Cholesterol (Chol) plays a crucial role in regulating membrane properties and biological processes such as membrane fusion, yet the molecular mechanisms underlying its function remain incompletely understood. In order to elucidate how sterol structure influences phospholipid organization relevant to membrane fusion, we compared the effects of Chol and its biosynthetic precursor lanosterol (Lan) on hydrated phosphatidylethanolamine (PE) assemblies using X-ray diffraction, the neutral flotation method, and osmotic stress measurements. Volumetric analyses revealed that Lan has a larger occupied molecular volume than Chol in the bilayers. These values were largely independent of differences between phospholipids (phosphatidylcholine and PE), indicating that sterols are deeply embedded within the bilayer. In palmitoyl-oleoyl-PE lamellar membranes, both sterols increased bilayer thickness. They both enhanced short-range repulsive hydration forces, but Chol suppressed fluctuation-induced repulsion more effectively, reflecting its greater stiffening effect. In bacterial PE systems forming the inverted hexagonal (H_II) phase, increasing sterol concentration decreased the lattice constant, with a more substantial effect for Lan, which also induced greater curvature of the water columns. These results suggest that while Chol enhances mechanical rigidity and membrane cohesion, Lan promotes molecular flexibility and curvature, properties associated with fusion intermediates. Full article

Carbon emission reduction strategies are crucial for addressing global climate change, with chemical absorption-based carbon capture technology being one of the core methods for achieving large-scale CO₂ mitigation. The current research focus in chemical absorption lies in selecting blended amine–catalyst systems and applying efficient absorption–desorption equipment. This study employs the Lattice Boltzmann Method (LBM) to simulate the catalytic CO₂ absorption process within an absorption column, obtaining data such as solution flow velocity, CO₂ absorption rate, and temperature distribution. The simulation results align well with experimental data from a continuous pilot-scale setup. Furthermore, the effects of different operating parameters and catalyst conditions on the absorption process were investigated. The findings indicate that higher catalyst volume fractions and smaller catalyst particle sizes enhance CO₂ absorption but may also lead to significant temperature rises across the column. Additionally, an optimized ternary amine–catalyst combination should be selected over a single amine to achieve superior CO₂ absorption capacity. Provided that the cyclic loading capacity is maintained, the absorbent solution flow rate should be minimized to ensure optimal absorption efficiency. Full article

As with wind turbines, marine tidal turbines are expected to be deployed in arrays of multiple turbines. To optimize these arrays, a more profound understanding of the interactions between turbines is necessary. This paper employs the Actuator Line Method alongside the Lattice Boltzmann Method and Large Eddy Simulation to develop a numerical model of tidal turbine arrays. It studies a vertical-axis turbine manufactured by HydroQuest/CMN that is equipped with two counter-rotating columns, each comprising two rotors. The ambient turbulence and upstream velocity profiles correspond to the characteristics of a tidal site such as the Alderney Race. Six turbine layouts are modeled: three aligned layouts with three turbines and three staggered layouts with four turbines. The spacing between turbines varies depending on the layout. This study yields several observations regarding array configuration. A minimum distance of 300 m, or $12D_{eq}$, between aligned turbines is necessary for full wake recovery. At shorter distances, the accumulation of velocity deficits significantly decreases the efficiency of the third turbine in the array. Pairs of counter-rotating vortices are observed in the wake of turbines. The evolution of these vortices and their influence on the wake depend greatly on the array configuration. An optimal configuration is observed in which the overall averaged power is not impaired by the interactions. Full article

This study presents an innovative solution to improve the mechanical performance of traditional cemented tailings backfill (CTB) by incorporating 3D-printed polymer lattice (3DPPL) reinforcements. We systematically investigated three distinct 3DPPL configurations (four-column FC, six-column SC, and cross-shaped CO) through comprehensive experimental methods including Brazilian splitting tests, digital image correlation (DIC), and scanning electron microscopy (SEM). The results show that the 3DPPL reinforcement significantly enhances the CTB’s tensile properties, with the CO structure demonstrating the most substantial improvement—increasing the tensile strength by 85.6% (to 0.386 MPa) at a cement-to-tailings ratio of 1:8. The 3DPPL-modified CTB exhibited superior ductility and progressive failure characteristics, as evidenced by multi-stage load-deflection behavior and a significantly higher strain capacity (41.698–51.765%) compared to unreinforced specimens (2.504–4.841%). The reinforcement mechanism involved synergistic effects of macroscopic truss behavior and microscopic interfacial bonding, which effectively redistributed the stress and dissipated energy. This multi-scale approach successfully transforms CTB’s failure mode from brittle to progressive while optimizing both strength and toughness, providing a promising advancement for mine backfill material design. Full article

This study established a numerical model for a foundation pit at the Zhongyilu Station of the Wuhan Metro Line 12, using Plaxis3D version 2021 finite element software to examine the horizontal displacement of the diaphragm wall, ground surface settlement, and differential settlement between the diaphragm wall and the lattice columns across various construction stages. A comparison with the cut-and-cover method prompted the adoption of a strategy that integrates segmental pouring of the main structure and the installation of internal supports to optimize the original scheme. The results indicated that as the foundation pit was excavated, both the horizontal displacement of diaphragm wall and the ground surface settlement gradually increased, while the differential settlement between the diaphragm wall and the lattice columns shows exhibited an initial decrease followed by an increase. In comparison to the cut-and-cover method, the cover-and-cut method demonstrated greater efficacy in controlling foundation pit deformation and minimizing disturbances to surrounding environment. As the number of segmental pouring layers and support levels increased, the overall deformation of the foundation pit showed a gradual decreasing trend, and the differential settlement between the diaphragm wall and the lattice columns continued to fluctuate. When each floor slab was poured in three layers with two supports placed in the middle, the maximum horizontal displacement of the diaphragm wall could be reduced by 22.47%, and the maximum ground surface settlement could be decreased by 19.01%. The findings in this research can provide valuable basis and reference for the design and construction of similar projects. Full article

This paper presents a numerical simulation and theoretical analysis of the eccentric compressive performance of a novel composite concrete-filled steel tube (CFST) latticed column with corrugated steel plates for industrial buildings. The influence of multiple parameters was systematically examined, encompassing the eccentricity ratio, material strengths (steel tube and concrete), corrugated steel plate waveform, and steel lacing tube strength. The results show that eccentric loading causes typical bending failure, with corrugated steel plates providing significant restraining effects, and diagonal lacing tubes optimizing load distribution and bending resistance. Increased eccentricity reduces the load capacity by up to 41.8% but improves the ductility by 50.6%, with benefits ceasing beyond 350 mm of eccentricity. A higher steel strength enhances the load capacity (28.6%) and ductility (14.5%), while a higher concrete strength improves the capacity but reduces the ductility. Longer waveforms in corrugated steel plates improve the stress redistribution, enhancing both capacity (19.1%) and ductility (9.7%). The eccentric compression modification formulas proposed in this study for the latticed column show a reliable calculation accuracy within 11% of simulations. Full article

Concrete-filled steel tube (CFST) columns reinforced with latticed steel angles (LSA), referred to as CFST-LSA columns, have been widely adopted in practical engineering. Understanding their mechanical behavior under eccentric loading is crucial for ensuring structural safety and performance in engineering applications. Previous experimental studies have demonstrated that the incorporation of steel angles substantially improves both the axial capacity and ductility of CFST-LSA columns. Existing methods for determining the eccentric bearing capacity of CFST-LSA columns primarily rely on the normalized N/N_u-M/M_u interaction curve. However, this approach involves a complex calculation procedure for evaluating the eccentric bearing capacity. To address this limitation, this study proposes a theoretical model based on the limit equilibrium method to predict the eccentric bearing capacity of CFST-LSA columns. The proposed model explicitly integrates fundamental geometric and material parameters, thereby enabling a more efficient and programmable calculation of the eccentric bearing capacity. Comparisons between the proposed model and experimental results show good agreement, with a tested-to-predicted eccentric resistance ratio of 1.085 and a coefficient of variation (COV) of 0.022. The proposed model can serve as a practical calculation method for eccentric loading of CFST-LSA columns, facilitating their application in high-rise buildings and long-span bridges. Full article

In this paper, the low-cycle reciprocating load test was carried out on four-limb concrete-filled steel tubular (CFST) lattice columns with different slenderness ratios and axial compression ratios, and the seismic performance was studied. Two performance indicators, namely damage and hysteretic energy dissipation, were defined as the objective functions, and the axial compression ratio was used as an optimization variable to perform the multi-objective optimization analysis of four-limb CFST lattice columns. Optimization using the max–min problem approach aims to optimize the axial compression ratio to minimize damage and maximize the dissipation of hysteresis energy. The seismic performances before and after optimization were determined using a restoring force model and were evaluated by the finite element method under different axial compression ratios. The results show that, under low-cycle reciprocating loads, the load–displacement hysteresis curve is a bow shape (Members 1 and 2), inverse S-shape (Member 3), and approximate shuttle shape (Member 4). Through multi-objective optimization, the optimized axial compression ratio is 0.25 and the finite element analysis indicates that the optimal seismic performance is at an axial compression ratio of 0.25. Through the optimized design, the maximum horizontal load of lattice columns, the elastic stiffness, the dissipation capacity, and the seismic performance are all improved, under the premise of satisfying the structural safety. Full article

A Scanning Photoelectron Microscopy (SPEM) experiment has been applied to ZnO:N films deposited by Atomic Layer Deposition (ALD) under O-rich conditions and post-growth annealed in oxygen at 800 °C. State-of-the-Art spatial resolution (130 nm) allows for probing the electronic structure of single column of growth. The samples were cleaved under ultra-high vacuum (UHV) conditions to open atomically clean cross-sectional areas for SPEM experiment. It has been shown that different columns reveal considerably different shape of the valence band (VB) photoemission spectra and that some of them are shifted towards the bandgap. The shift of the VB maximum, which is associated with hybridization with acceptor states, was found to be correlated with carbon content measured as a relative intensity of the $C1s$ and $Zn3d$ core levels. Generalized Gradient Approximation (GGA) supplemented by +U correction was applied to both $Zn3d$ and $O2p$ orbitals for calculation of the $V_{\mathrm{Zn}}$ migration properties by the Nudged Elastic Band (NEB) method. The results suggest that interstitial -${\mathrm{CH}}_x$ groups facilitate the formation of acceptor complexes due to additional lattice perturbation. Full article

Metallurgical industrial buildings, particularly those over 10 years old, frequently experience increased vibrations in their latticed columns due to prolonged dynamic loads from cranes, affecting both structural safety and usability. To enhance the strength and stiffness of these structures in a cost-effective way, a novel composite latticed column made from concrete-filled steel tubes and corrugated steel plates is proposed. An analytical study on its axial compression behavior has also been conducted. The analytical parameters included the yield strength of steel tube and compressive strength of concrete, the waveform of corrugated steel plate, as well as the thickness, yield strength, and configuration of steel lacing tubes. Results show that compared to specimens with C30 concrete, the bearing capacity and initial axial stiffness of specimens with C50 concrete can increase by 35% and 33%, respectively. Compared with the steel specimen with yield strength of 235 MPa, the peak bearing capacity of the steel specimen with yield strength of 400 MPa can be increased by 28%. Additionally, increasing the wave height reduces the concrete cross section, resulting in a decrease in axial stiffness and ductility. Compared to specimens with horizontal lacing tubes, those with diagonal lacing tubes exhibit increases in ductility and axial stiffness of 33% and 12%, respectively. Therefore, diagonal lacing tubes should be considered for the optimal axial compression behavior of latticed columns. Furthermore, a model for predicting the axial compression bearing capacity of latticed columns with CFST tubes and corrugated steel plates was proposed. Full article

Seismic metamaterials are an emerging vibration-damping technology, yet concentrating the bandgap in the low-frequency range remains challenging due to the constraints imposed by lattice size. In this study, we numerically investigated seismic metamaterials connected by auxetic (negative Poisson’s ratio) slender strips, which exhibit an exceptionally wide low-frequency band gap for vibration isolation. Using a finite element method, we first performed a comparative analysis of several representative seismic metamaterial configurations. The results showed that the auxetic thin strip-connected steel column structure demonstrated outstanding performance, with the first complete band gap starting at 1.61 Hz, ending at 80.40 Hz, spanning a width of 78.79 Hz, and achieving a relative bandwidth of 192.15%. Notably, while most existing designs feature lattice constants in the ten-meter range (with the smallest around two meters), our proposed structure achieves these results with a lattice constant of only one meter. We further analyzed the transmission characteristics of the steel column structure, both with and without concrete filling. Interestingly, significant vibration attenuation, approaching 70 dB, was observed below the first complete band gap (approximately 0.22–1.17 Hz), even without the use of concrete. By comparing the flexural wave band gap with the transmission spectrum, we attributed this attenuation primarily to the presence of the band gap, a phenomenon often overlooked in previous studies. This attenuation at lower frequencies highlights the potential for effectively reducing low-frequency vibration energy. To further enhance the attenuation, the number of periods in the propagation direction can be increased. Additionally, we systematically explored the influence of geometric parameters on the first complete band gap. We found that optimal results were achieved with a slender strip length of 0.05 m, its width between 0.05 and 0.1 m, and a steel structure width of 0.1 m. Our findings underscore the critical role of auxetic thin strips in achieving broadband low-frequency vibration isolation. The approach presented in this study, along with the discovery of low-frequency flexural wave band gaps, provides valuable insights for seismic engineering and other applications requiring effective vibration reduction strategies. Full article

All-d metallic Heusler compounds are promising materials for nanoelectronic applications. Such materials combining 3d, 4d, and 5d atoms have not yet been studied. In this respect, we perform ab initio electronic structure calculations and focus on ${\mathrm{Co}}_2$MnZ, ${\mathrm{Rh}}_2$MnZ, and ${\mathrm{Ru}}_2$MnZ compounds, where Z represents transition metal atoms from groups 3B, 4B, 5B, and 6B of the periodic table. Our results demonstrate that most of these compounds exhibit a distinctive region of very low minority-spin state density at the Fermi level when crystallized in the $L{2}_1$ lattice structure. The Co-based compounds follow a Slater–Pauling behavior for their total spin magnetic moments, while the Ru-based compounds consistently deviate from the predicted Slater–Pauling values. Rh-based compounds show similarities to Co-based compounds for lighter Z atoms and to Ru-based compounds for heavier Z atoms. We find that the choice of the Z element within the same periodic table column has only a minor effect on the results, except for the ${\mathrm{Rh}}_2$Mn(Cr, Mo, W) compounds. Our findings suggest that these compounds hold significant promise for applications in spintronics and magnetoelectronics. Full article

This study investigates the flexural behavior of 3D-printed multi-topology lattice beams, with a specific emphasis on octet and cube lattice geometries created through fused deposition modeling (FDM). The mechanical properties of these beams were evaluated through quasi-static three-point bending tests. A comparative analysis of load-carrying capacity, energy absorption, and specific energy absorption (SEA) indicates that octet lattice beams exhibit superior performance to cube lattice beams. The octet lattice beam in the triple-layer double-column (TL-DC) arrangement absorbed 14.99 J of energy, representing a 38% increase compared to the 10.86 J absorbed by the cube lattice beam in the same design. The specific energy absorption (SEA) of the octet beam was measured at 0.39 J/g, which exceeds the 0.29 J/g recorded for the cube beam. Two distinct types of deformations were identified for the struts and the beam layers. Octet struts exhibit enhanced performance in stretch-dominated zones, whereas the cube system demonstrates superior efficacy in compressive-dominated regions. The results highlight the enhanced efficacy of octet lattice structures in energy absorption and mechanical stability maintenance. The investigation of sandwich lattice topologies integrating octet and cube structures indicates that while hybrid designs may exhibit efficiency, uniform octet structures yield superior performance. This study provides valuable insights into the structural design and optimization of lattice systems for applications requiring high-energy absorption and mechanical robustness. Full article

Tyramine (TRM) is a biogenic catecholamine neurotransmitter, which can trigger migraines and hypertension. TRM accumulated in foods is reduced and detected using additive cyclodextrins (CDs) while their association characteristics remain unclear. Here, single-crystal X-ray diffraction and density functional theory (DFT) calculation have been performed, demonstrating the elusive pseudopolymorphs in β-CD inclusion complexes with TRM base/HCl, β-CD·0.5TRM·7.6H₂O (1) and β-CD·TRM HCl·4H₂O (2) and the rare α-CD·0.5(TRM HCl)·10H₂O (3) exclusion complex. Both 1 and 2 share the common inclusion mode with similar TRM structures in the round and elliptical β-CD cavities, belong to the monoclinic space group P2₁, and have similar herringbone packing structures. Furthermore, 3 differs from 2, as the smaller twofold symmetry-related, round α-CD prefers an exclusion complex with the twofold disordered TRM–H⁺ sites. In the orthorhombic P2₁2₁2 lattice, α-CDs are packed in a channel-type structure, where the column-like cavity is occupied by disordered water sites. DFT results indicate that β-CD remains elliptical to suitably accommodate TRM, yielding an energetically favorable inclusion complex, which is significantly contributed by the β-CD deformation, and the inclusion complex of α-CD with the TRM aminoethyl side chain is also energetically favorable compared to the exclusion mode. This study suggests the CD implications for food safety and drug/bioactive formulation and delivery. Full article