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This paper investigates the well-posedness, the existence and the regularity of the time-dependent global attractor for a viscoelastic equation in Ω ⊂ R 3 : | ∂ t u | ρ ∂ t t u − ∂ t t Δ u − h t (0) Δ u − ∫ 0 ∞ ∂ s h t (s) Δ u (t − s) d s + f (u) = h with time-dependent memory kernel which is used to model aging phenomena of the material. By using the novel theory framework recently developed in literature (Conti et al., 2018 [12,13]) and establishing some delicate integration estimates along the trajectory of the solutions in the time-dependent phase space, we show that when ρ ∈ (1 , 4 ] , the growth exponent p of f (u) is up to the critical range 1 ≤ p ≤ 5 , and the time-dependent memory kernel satisfies the same conditions as in Conti et al., (2018) [12,13], the model is well-posed. Especially, when ρ ∈ (1 , 4) and 1 ≤ p < 5 , the related process has an invariant time-dependent global attractor which has optimal regularity. [ABSTRACT FROM AUTHOR]

This paper investigates the stability of strong exponential attractors with respect to dissipative index θ ∈ [ 1 / 2 , 1) for the Kirchhoff wave model with structural nonlinear damping: u t t − ϕ (‖ ∇ u ‖ 2) Δ u + σ (‖ ∇ u ‖ 2) (− Δ) θ u t + f (u) = g (x). It proves that for each θ 0 ∈ [ 1 / 2 , 1) , there exists a family of strong bi-space exponential attractors, which are also the standard exponential attractors of optimal regularity and are Hölder continuous at the point θ 0 in the topology of the strong solution space provided that the nonlinearity f (u) is of the optimal subcritical growth. The method used here allows to overcome the difficulties in literatures before to get the Lipschitz continuity and quasi-stability of the evolution semigroup S θ (t) to obtain the desired result. [ABSTRACT FROM AUTHOR]

• Development of SCFST stub column internally reinforced by CFRP profile. • Axial compression tests on 10 SCFST-CFRP columns and 2 SCFST columns. • Study of mechanical properties of SCFST-CFRP column with varying parameters. • Evaluation of existing design codes of AIJ, EC4, AISC-LRFD, and GB50936. • Development of empirical equations for column axial load capacity. This paper presents experimental and numerical investigations of an innovative composite column, which is formed using a square concrete filled steel tubular (SCFST) column internally reinforced by a carbon fiber reinforced polymer (CFRP) profile (referred to as SCFST-CFRP column), under axial compression. Full-scale axial compression tests were conducted on ten SCFST-CFRP columns with different steel ratios and steel grades and two traditional SCFST columns. The test results, including failure mode, axial load–displacement response, and strain development, were analyzed to examine the column behavior under axial compression. Numerical models of SCFST-CFRP columns were developed and validated to further investigate the stress distribution and load-bearing contribution of each column component. The validated models were then used for parametric studies that evaluated the effects of material and structural parameters on column behavior and axial load capacity. Besides, design rules, as suggested in the codes of AIJ, EC4, AISC-LRFD, and GB50936, were evaluated using experimental and numerical data for axially loaded SCFST-CFRP columns. In addition, empirical equations were developed through unified criteria to predict the SCFST-CFRP column capacity under axial compression. [ABSTRACT FROM AUTHOR]

• Conducted eccentric compression tests on 18 CFSST-CFRP long column. • Investigated eccentrically loaded behavior and resistance of CFSST-CFRP column. • Evaluated effects of slenderness ratios and load eccentricity ratio. • Analyzed load bearing capacity and load-transferring mechanism. • Performed parametric studies on column bearing capacity. • Developed design equations to predict ultimate eccentric load capacity. This study investigated behavior of concrete filled square steel tubular (CFSST) columns encased with I-shaped CFPR under eccentric compression. Full-scale eccentric compression tests were conducted on eighteen column specimens consisting of square steel tube, concrete, and an I-shaped CFRP profile. The test program considered effects of load eccentricity ratio and column slenderness ratio. The eccentrically loaded column behavior was investigated with respect to the mid-height deflection, load, and failure modes. The development and distribution of longitudinal strain and neural axis for the column were also studied. Finite element models were developed and validated against tested results to further analyze the load-transferring mechanism of the composite column and perform detailed parametric studies. The results indicated that the CFSST column encased with I-shaped CFRP behaved in a ductile manner with the improved capacity and increased stability. Finally, design equations were developed using tested and simulated data to estimate ultimate bearing capacity of the CFSST column encased with I-shaped CFRP when subjected to eccentric compression. The predicted column capacities using the design equations matched well with the tested and simulated capacities. [ABSTRACT FROM AUTHOR]

• High-strength CFSST stub column with an encased I-shaped CFRP profile was proposed. • Axial compression test was performed on HCFHSST-CFRP stub column. • Investigated effects of material strengths and steel ratio on column behavior. • The combinations of high-strength materials and CFRP improved column resistance. • Formulas were proposed to predict ultimate axial load capacity. A new composite column that consists of high-strength square steel tube, high-strength concrete, and carbon fiber reinforced polymer (CFRP) profile with a I-shaped cross section was developed and investigated in this study. This paper experimentally and numerically investigated axially loaded behavior of high-strength concrete filled high-strength steel tubular (HCFHSST) stub column with an encased I-shaped CFRP profile. In the experimental study, axial compression tests were completed on eight specimens to examine the axial load response of the composite column, including the load–displacement curves, failure mode, and strain distribution. Finite element models of the composite column were developed using ABAQUS and validated by comparing numerical results with experimental data. The validated models were used to further investigate the load sharing and transferring mechanism for each component of the composite column. Results showed that the composite column comprehensively used the advantageous merits of concrete, steel tube, and CFRP as a unit to share the applied load at different loading stages: linearly elastic, elastic–plastic, hardening, post-peak descending, and residual plateau stage. Parametric studies were performed that assessed influences of critical design parameters on the axially loaded behavior of the stub column. The examined parameters included the compressive strength of high-strength concrete, yield strength of high-strength steel, and steel ratio. Finally, empirical equations were proposed to determine the ultimate vertical strain and the ultimate axial load capacity of the HCFHSST stub column encased with a I-shaped CFRP profile. [ABSTRACT FROM AUTHOR]

• Fly ash and costless seawater are used to sequester CO 2 at ambient conditions. • High carbonation efficiency of up to 94.8% is obtained. • The carbonation efficiency increased with the solid/liquid and the CO 2 flow rate. • The absorbed CO 2 is converted to aragonite. • The low pH range of 8.2 ∼ 10.4 may be the key to the high carbonation efficiency. Direct CO 2 mineralization using fly ash is a promising technology to achieve CO 2 sequestration. Seawater's abundance and calcium-rich composition make it an attractive substitute solution for CO 2 sequestration. However, there have been limited studies conducted so far, and the mineralization mechanism remains unclear, which has constrained its industrial application potential. Here we utilized low CaO-content fly ash in combination with seawater to perform direct CO 2 mineralization under ambient conditions, achieving a remarkable carbonation efficiency of 94.8 %. Upon scrutinizing the carbonate parameter evolution, we identify a crucial pH range (8.2 ∼ 10.4) that enhances calcium elution efficiency, leading to heightened carbonation efficiency. The involvement of Mg(OH) 2 within this pH range influences CaCO 3 precipitation kinetics and crystalline phase. This innovative approach holds promise for carbon sequestration and presents a valuable contribution to sustainable CO 2 utilization strategies. [ABSTRACT FROM AUTHOR]

Dislocation climb plays an important role in understanding plastic deformation of metallic materials at high temperature. In this paper, we present a continuum formulation for dislocation climb velocity based on densities of dislocations. The obtained continuum formulation is an accurate approximation of the Green's function-based discrete dislocation dynamics method (Gu et al., 2015). The continuum dislocation climb formulation has the advantage of accounting for both the long-range effect of vacancy bulk diffusion and that of the Peach–Koehler climb force, and the two long-range effects are canceled into a short-range effect (integral with fast-decaying kernel) and in some special cases, a completely local effect. This significantly simplifies the calculation in the Green's function-based discrete dislocation dynamics method, in which a linear system has to be solved over the entire system for the long-range effect of vacancy diffusion and the long-range Peach–Koehler climb force has to be calculated. This obtained continuum dislocation climb velocity can be applied in any available continuum dislocation dynamics frameworks. We also present numerical validations for this continuum climb velocity and simulation examples for implementation in continuum dislocation dynamics frameworks. • We developed a continuum formulation based on dislocation densities, as an accurate approximation of the Green's function-based discrete dislocation dynamics method. • The continuum formulation accounts for both the long-range effect of vacancy bulk diffusion and that of the Peach–Koehler climb force, and the two long-range effects are canceled into a short-range effect (integral with fast-decaying kernel) and in some special cases, a completely local effect. • The continuum formulation has also been generalized to include the pipe diffusion-assisted self-climb based on the discrete self-climb dislocation dynamics model. • The obtained continuum dislocation climb velocity formulation can be applied in any available continuum dislocation dynamics frameworks. [ABSTRACT FROM AUTHOR]

The advent of hydrogel-based flexible strain sensors has generated enormous research interest due to their outstanding biocompatibility. However, developing hydrogel-based strain sensors with high gauge factor, wide detection range and multifunctional integration is still challenging. Here, a novel multifunctional hydrogel-based strain sensor is composed of two-dimensional transition metal carbides/nitrides (Ti 3 C 2 Tx MXene) and Polyacrylamide- co -Poly- N -hydroxyethylene acrylamide/Carboxy Methyl Cellulose-Fe3+ dual network structure (PAAm-PHEMAA/CMC-Fe3+) with multiple hydrogen bonds and coordination interactions. The dual network design endowed the hydrogel-based human motion sensor with fast rebound and high tensile properties, enabling it to exhibit high sensitivity (response time ∼120 ms and gauge factor ∼1.62), and a wide detection range (0–700%), including joint movements as well as more subtle human motions (facial micro-expression changes and speech). More importantly, the hydrogel-based strain sensor exhibited excellent EMI (41 dB, X-band) and UV shielding properties (365 nm, 100%, 0.5 mm) due to the synergy of porous structure, moderate conductivity, and ionic solution environment. Moreover, it demonstrated robust adhesion (29 kPa), high shape adaptability, and self-healing capability. This innovative multi-functional flexible sensor design provides guidance for the development, research and application of high-performance flexible wearable materials. A novel multifunctional hydrogel-based strain sensor consisted of MXene, dual-network structure (PAAm-PHEMAA/CMC-Fe3+) with multiple hydrogen bonds and coordination interactions, which demonstrated a high sensitivity and a wide detection range, conductive, EMI shielding, UV protection, self-adhesive, and healing properties. [Display omitted] • The MXene-based dual network hydrogel is comprised of PAAm-PHEMAA and CMC-Fe3+. • Hydrogels contain multiple hydrogen bonds and coordination interactions. • Hydrogels exhibit excellent ductility, stimulation sensitivity and self-adhesion. • As a strain sensor, hydrogels can precisely monitor human movement and vital signs. • The sensor can efficiently shield electromagnetic wave and UV light. [ABSTRACT FROM AUTHOR]

The interfacial interaction and the microstructure evolution play a vital role in the mechanical properties of thermoplastic polyurethane (TPU) based energetic composites. In this work, inspired by the strong adhesion of mussels, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) energetic crystals were coated with polydopamine (PDA) via in-situ polymerization of dopamine and then dispersed in TPU matrix. The core-shell structure of CL-20@PDA was confirmed by in-depth structural characterizations. The uniform and compact PDA shell gave rise to a high thermal stability with phase transition temperature of CL-20 crystals increased by 11.5 °C. Moreover, the PDA modification endowed the TPU based composites with excellent mechanical properties. A striking increase in mechanical properties and creep resistance was achieved with 6 h polymerization time of PDA. Compared with the PBX-Raw with untreated CL-20 crystals, the compressive and tensile strength after PDA coating increased by 115% and 57%, and the compressive and tensile fracture energy increased by 148% and 68%. The storage modulus at 25 °C was 40% higher than PBX-Raw. The enhancement effectivity could be ascribed to both interfacial interaction and the microstructure evolution of TPU binder. The theoretical simulations by molecular dynamics demonstrated the strong interfacial interaction mechanism between CL-20 and PDA. Moreover, the abundant hydrogen bonds between the hard segments of TPU and functional groups of PDA facilitated the formation of more hard microdomains which acted as physical crosslinking points to promote the phase separation. This work provides a potential method for the mechanical and thermal enhancement for TPU based energetic materials based on dopamine chemistry. Inspired by the strong chemical adhesion of mussels, the polymerization of dopamine was introduced to coat energetic crystals, which play a vital role in the interfacial interaction and the microstructure evolution of thermoplastic polyurethane (TPU) binder, resulted in mechanical and thermal enhancement for TPU based energetic materials. [Display omitted] • Core-shell structure was constructed through a novel, facile and general route via self-polymerization of dopamine. • CL-20@PDA composites exhibited 11.5 °C higher phase transition (ε.→γ) temperature than that of pure CL-20. • The mechanical enhancement was disclosed based on interfacial interaction and the microstructure evolution of TPU binder. • Theoretical simulations for the interfacial interaction showed good accordance with the experimental observations. [ABSTRACT FROM AUTHOR]

This study proposes an CIP (Constraint Interpolation Profile) viscous flow model that couples the Finite Element Method for structural deformation, to investigate the wave interaction with a fluid-filled membrane submerged breakwater. A modified ghost-cell immersed boundary method is adopted to achieve an accurate simulation of the fluid-structure interaction. After validation by published experimental data, the model is used to study the interaction between regular waves and a fluid-filled membrane submerged breakwater. The excess internal pressure, vorticity field, elastic modulus and structural responses are analyzed. The results show that, in lower excess internal pressure, the wave reflection, vortex shedding and energy dissipation are more significant. Besides, through the analysis of displacement and velocity distribution, three different vibration modes of the membrane structure are identified at different wave frequencies. • An FDM-FEM viscous flow model is proposed for wave and membrane breakwater interaction. • Internal pressure, vorticity field, elastic modulus and structural responses of a membrane breakwater is investigated. • The wave reflection, vortex shedding and energy dissipation are found to be more significant in lower internal pressures. • Three different vibration response modes of the membrane structure are found at different wave frequencies. [ABSTRACT FROM AUTHOR]

The effect of abrasive grain size on the material removal performances of the grinding surface was studied by theoretical modeling and grinding experiments. The results indicted that a smaller abrasive grain size of the abrasive belts led to smaller microscopic contour height and surface roughness of the ground surfaces, fewer curl chips, and more spherical chips. The smaller grain size also led to smaller macroscopic grinding depth and material removal rate. There was an approximately linear relationship between the macroscopic grinding depth and material removal rate during plane grinding. The slope was related to the abrasive grain size. Grinding force, vibration, vision, and sound signals could distinguish the macroscopic material removal changes caused by abrasive belt particle sizes. [ABSTRACT FROM AUTHOR]

The diabetic wound is easily to develop into a chronic wound because of the extremely serious and complex inflammatory microenvironment including biofilm formation, over-expressed reactive oxygen species (ROS), hypoxia and insufficiency of nitric oxide (NO) synthesis. In this work, a multifunctional hydrogel was designed and prepared by crosslinking hydrophilic poly(PEGMA- co -GMA- co -AAm) (PPGA) polymers with hyperbranched poly-L-lysine (HBPL)-modified manganese dioxide (MnO 2) nanozymes. Pravastatin sodium, which is supposed to participate in the synthesis of NO, was further loaded to obtain the HMP hydrogel. The capabilities of this hydrogel in scavenging different types of ROS, generating O 2 , killing broad spectrum bacteria, and protecting cells against oxidative stress were confirmed in vitro. The transcriptome analysis revealed that HBPL inhibited bacterial quorum sensing (QS) system, downregulated virulent genes, and interfered bacterial metabolism. The HBPL-crosslinked hydrogels killed up to 94.1%–99.5% of methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli (E. coli) and Pseudomonas aeruginosa even at 109 CFU/mL. HBPL modification greatly increased the stability of MnO 2 nanosheets in physiological environment. The MRSA-caused infection was effectively treated by the HBPL-crosslinked HMP hydrogel in vivo , and thereby the wound closure at inflammatory phase was promoted significantly. The treatment of HMP hydrogel reduced the ROS degree and relieved the inflammatory level significantly, accompanied by the decreased neutrophil infiltration and enhanced M2-type macrophage polarization in vivo. Significantly lower levels of inflammatory factors such as interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α) and chemokines-1 (CXCL-1), and higher levels of anti-inflammatory cytokines such as IL-4 and IL-10 were also confirmed. Moreover, the HMP hydrogel could promote the secretion of transforming growth factor-β (TGF-β) and stimulate neovascularization, and deposition of collagen with a thicker skin and epithelium structure. [ABSTRACT FROM AUTHOR]

• We propose a novel multi-scale semi-supervised clustering method, termed MAGIC, to disentangle the heterogeneity of brain diseases. • We perform extensive semi-simulated experiments on large control samples (UK Biobank, N = 4403) to precisely quantify performance under various conditions, including varying degrees of brain atrophy, different levels of heterogeneity, overlapping disease subtypes, class imbalance, and varying sample sizes. • We apply MAGIC to MCI and Alzheimer's disease (ADNI, N = 1728) and schizophrenia (PHENOM, N = 1166) patients to dissect their neuroanatomical heterogeneity, providing guidance regarding the use of the semi-simulated experiments to validate the subtypes found in actual clinical applications. Disease heterogeneity is a significant obstacle to understanding pathological processes and delivering precision diagnostics and treatment. Clustering methods have gained popularity for stratifying patients into subpopulations (i.e., subtypes) of brain diseases using imaging data. However, unsupervised clustering approaches are often confounded by anatomical and functional variations not related to a disease or pathology of interest. Semi-supervised clustering techniques have been proposed to overcome this and, therefore, capture disease-specific patterns more effectively. An additional limitation of both unsupervised and semi-supervised conventional machine learning methods is that they typically model, learn and infer from data using a basis of feature sets pre-defined at a fixed anatomical or functional scale (e.g., atlas-based regions of interest). Herein we propose a novel method, "Multi-scAle heteroGeneity analysIs and Clustering" (MAGIC), to depict the multi-scale presentation of disease heterogeneity, which builds on a previously proposed semi-supervised clustering method, HYDRA. It derives multi-scale and clinically interpretable feature representations and exploits a double-cyclic optimization procedure to effectively drive identification of inter-scale-consistent disease subtypes. More importantly, to understand the conditions under which the clustering model can estimate true heterogeneity related to diseases, we conducted extensive and systematic semi-simulated experiments to evaluate the proposed method on a sizeable healthy control sample from the UK Biobank (N = 4403). We then applied MAGIC to imaging data from Alzheimer's disease (ADNI, N = 1728) and schizophrenia (PHENOM, N = 1166) patients to demonstrate its potential and challenges in dissecting the neuroanatomical heterogeneity of common brain diseases. Taken together, we aim to provide guidance regarding when such analyses can succeed or should be taken with caution. The code of the proposed method is publicly available at https://github.com/anbai106/MAGIC. [Display omitted] [ABSTRACT FROM AUTHOR]

Polytetrafluoroethylene/Aluminum (PTFE/Al) composite with high energy density and combustion reaction performance has received widespread attention in the field of propellants, explosives, and pyrotechnics. In order to precisely control combustion reaction and energy output performance, gradient structured PTFE/Al composite (mass and diameter gradient) has been designed and constructed through 3D printing technology. PTFE/Al ink is prepared by acoustic resonance mixing to control rheological properties (viscosity and modulus) for 3D printing technology. The largest reaction heat (7749.95 J/g) and burning rate (~130 mm/s) are achieved for gradient lines with diameter of 2.42 mm and mass ratio of 60:40 (PTFE/Al). Moreover, the progressive change from steady combustion to deflagration containing three stages of pressure output is observed for gradient structured PTFE/Al cylinder. This work reveals that gradient structure could provide new strategy to tune energy output and combustion performances, which can promote the practical application of PTFE/Al reactive materials. [ABSTRACT FROM AUTHOR]

Polymer bonded explosives (PBXs) have weak strength and toughness, as well as they are prone to fracture under stress. To overcome these disadvantages, inspired by the strong adhesion of mussels and the hierarchical structure of nacre, we designed and fabricated novel PBX composites by coating three explosive crystals (2,6-diamino-3,5-dinitropyrazine-1-oxide, LLM-105; 1,3,5-triamino-2,4,6-trinitrobenzene, TATB; and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane, HMX) with polydopamine (PDA), respectively. The results of mechanical analysis and in situ small angle neutron scattering measurements showed that these novel PBX composites exhibited higher strength, stronger toughness, and higher creep resistance, and higher microstructural thermal stability simultaneously, compared to PBXs without multiple bio-inspired designs. Contact angles measurements indicated that the interfacial interaction intensities between energetic crystals and polymer binder could be largely enhanced by PDA coating on energetic crystals. Theoretical calculations revealed that PDA-modified PBX-LLM-105 achieved the most increment in mechanical strength, which were well consistent with the experiments. An enhancement mechanism combining the van der Waals forces, π–π interaction, and hydrogen bonds, as well as surface roughness was proposed to account for the variety of mechanical properties and microstructural thermal stability of PDA-modified PBXs. The results revealed in this study are commonly significant to interfacial modification and performance enhancement of materials. [Display omitted] • Multiple bio-inspired designs were applied successfully to balance the strength and toughness ofPBXs. • The bio-inspired designs have significantly enhanced the mechanical strength, creep resistance, and thermal stability of PBXs. • The molecular structures and surface roughness of energetic materials have great effect on the interfacial interaction. • The inter-facial interaction enhancement mechanism of polydopamine on different explosive crystals were detailedly revealed. [ABSTRACT FROM AUTHOR]