•FRP bars are applied in seawater coral aggregate concrete.•Hoop effect is weaker for coral concrete in compression compared to normal concrete.•Bond performance between FRP bars and seawater coral ...aggregate concrete is clarified.•A four-linear bond stress-slip model is proposed to describe the local bond behavior.•Local bond parameters are determined analytically based on fracture mechanics.
Application of FRP (fiber reinforced polymer) and SCAC (seawater coral aggregate concrete) in island construction can overcome the shortcomings in conventional steel and concrete. This paper is concerned with the bond performance between FRP bars and SCAC by pullout tests. The effect of fiber type, diameter and bond length of FRP bar and curing condition on the bond behavior is analyzed. It is found that the maximum average bond stress decreases with the increasing of the bond length and the bar diameter. The bond strength is slightly reduced for the specimens immersed in seawater compared to those cured in standard condition for FRP bars bonded to SCAC. Moreover, a four-linear model for local bond stress-slip relationship is proposed with four characteristic parameters, and an analytical approach is then presented to predict the maximum pullout load based on the model. The analytical results show good agreement with the experimental ones, and the proposed four-linear model with four characteristic parameters proves to be reasonable in the present study.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
The use of seawater sea sand concrete (SSSC) and fiber-reinforced polymer (FRP) has broad application prospect in island and coastal areas. However, the elastic modulus of FRP reinforcement is ...obviously lower than that of ordinary steel reinforcement, and the properties of SSSC are different from that of ordinary concrete, which results in a limit in the bearing capacity and stiffness of structures. In order to improve the flexural performance of FRP-reinforced SSSC beams, a novel SSSC beam with built-in glass FRP (GFRP) tubes was proposed in this study. Referring to many large-scale beam experiments, one specimen was used for one situation to illustrate the study considering costs and feasibility. Firstly, flexural performance tests of SSSC beams with GFRP tubes were conducted. Then, the effects of the GFRP tubes’ height, the strength grades of concrete inside and outside the GFRP tubes, and the GFRP reinforcement ratio on the flexural behaviors of the beams were investigated. In addition, the concept of capacity reserve was proposed to assess the ductility of the beams, and the interaction between the concrete outside the GFRP tube, the GFRP tube and concrete inside the tube was discussed. Finally, the formulas for the normal section bearing capacity of beams with built-in GFRP tubes were derived and verified. Compared to the beam without GFRP tubes, under the same conditions, the ultimate bearing capacities of the SSSC beam with 80 mm, 100, and 200 mm height GFRP tubes were increased by 17.67 kN, 24.52 kN, and 144.42 kN, respectively.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Particle tuned mass damper has received considerable attention on mitigating structural seismic responses recently. However, soil-structure interaction effects have not been considered for the ...optimization design of particle tuned mass damper in the previous studies yet, which may play significant roles in particle tuned mass damper’s effectiveness. This paper investigates the seismic control performance of particle tuned mass damper for tall buildings considering SSI effects. A 40-story benchmark structure is adopted as the primary structure, and different soil conditions including soft, medium, dense soil, and the fixed-base case are considered. Based on the Cuckoo Search algorithm, an optimum design approach for the particle tuned mass damper implemented in SSI system under earthquake excitations is proposed, and the optimum parameters of particle tuned mass damper are obtained from the optimum design process. The optimum results indicate that the optimized particle tuned mass damper can effectively decrease the displacement response without the increase of peak acceleration, and the reduction rates could exceed 30% in some cases. Compared with other soil type cases, under soft soil condition, the optimum parameters of particle tuned mass damper are especially different, and the mitigation effects of the optimized particle tuned mass damper on maximum displacement weaken. Hence, it is necessary to consider the SSI effects for particle tuned mass damper’s seismic design. Furthermore, the interaction effects between the primary structure and particle tuned mass damper in SSI system are also evaluated through energy analysis. The results show that considering SSI effects, the optimized particle tuned mass damper device dissipates the overwhelming majority of the input energy, and it greatly decreases the structural energy, displaying excellent energy dissipation performance on seismic vibration control of structure.
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Mitochondrial stress releases mitochondrial DNA (mtDNA) into the cytosol, thereby triggering the type Ι interferon (IFN) response. Mitochondrial outer membrane permeabilization, which is required for ...mtDNA release, has been extensively studied in apoptotic cells, but little is known about its role in live cells. We found that oxidatively stressed mitochondria release short mtDNA fragments via pores formed by the voltage-dependent anion channel (VDAC) oligomers in the mitochondrial outer membrane. Furthermore, the positively charged residues in the N-terminal domain of VDAC1 interact with mtDNA, promoting VDAC1 oligomerization. The VDAC oligomerization inhibitor VBIT-4 decreases mtDNA release, IFN signaling, neutrophil extracellular traps, and disease severity in a mouse model of systemic lupus erythematosus. Thus, inhibiting VDAC oligomerization is a potential therapeutic approach for diseases associated with mtDNA release.
The intention of this paper is to analyze the properties of coral aggregate concrete (CAC) that is reinforced by alkali-resistant glass fibers (ARGF) and the bond performance with BFRP (basalt fiber ...reinforced polymer) bars. Two types of ARGF, denoted by Type A and Type B with different manufacturing technologies and fiber lengths, are used in the test. Tests of compressive strength, splitting tensile strength, and flexural performance were performed on ARGF-CAC with four different contents for the two types of ARGF. It is found that the cubic compressive strength is slightly reduced when the fiber volume fraction exceeds 0.5%, but almost keeps invariable if the fiber content further increases. However, the tensile strength, residual strength retention and flexural toughness are improved as more ARGFs are added into CAC, and even higher with Type B ARGF addition. The optimized volume fraction is 1.5% for both the two types of ARGF based on the evaluation of the workability and mechanical performance. Moreover, central pull-out test was performed to study the bond properties of ARGF-CAC with BFRP bars. It is found that both the maximum average bond stress and residual frictional stress are generally reduced as the bond length is longer. The addition of Type B ARGFs can significantly improve the bond strength; however, the Type A ARGFs seem to have marginal effect.
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A slab laser based on Nd:CTGS crystal was reported for the first time. With a quasi-continuous wave semiconductor laser as the pump source, the maximum average output power reached 7.01 W, with a ...wavelength of 1064.5 nm, a single-pulse energy of 35 mJ, and a slope efficiency of 31%. Using a Cr 4+ :YAG crystal as the saturable absorber, the maximum average output power was 2.52 W, corresponding to a single-pulse energy of 1.26 mJ, a pulse duration of 37.2 ns, and a peak power reaches 33.9 kW. This work provides a good way to obtain pulsed slab lasers with simple structure and excellent performance, which are expected to be utilized in many fields like the photovoltaic industry, glass processing, tool manufacturing, mechanical engineering, and scientific research.
Resveratrol, a natural polyphenolic compound that is found in grapes and red wine, increases metabolic rate, insulin sensitivity, mitochondrial biogenesis, and physical endurance and reduces fat ...accumulation in mice. Although it is thought that resveratrol targets Sirt1, this is controversial because resveratrol also activates 5' AMP-activated protein kinase (AMPK), which also regulates insulin sensitivity and mitochondrial biogenesis. Here, we use mice deficient in AMPKalpha1 or -alpha2 to determine whether the metabolic effects of resveratrol are mediated by AMPK.
Mice deficient in the catalytic subunit of AMPK (alpha1 or alpha2) and wild-type mice were fed a high-fat diet or high-fat diet supplemented with resveratrol for 13 weeks. Body weight was recorded biweekly and metabolic parameters were measured. We also used mouse embryonic fibroblasts deficient in AMPK to study the role of AMPK in resveratrol-mediated effects in vitro.
Resveratrol increased the metabolic rate and reduced fat mass in wild-type mice but not in AMPKalpha1(-/-) mice. In the absence of either AMPKalpha1 or -alpha2, resveratrol failed to increase insulin sensitivity, glucose tolerance, mitochondrial biogenesis, and physical endurance. Consistent with this, the expression of genes important for mitochondrial biogenesis was not induced by resveratrol in AMPK-deficient mice. In addition, resveratrol increased the NAD-to-NADH ratio in an AMPK-dependent manner, which may explain how resveratrol may activate Sirt1 indirectly.
We conclude that AMPK, which was thought to be an off-target hit of resveratrol, is the central target for the metabolic effects of resveratrol.
Amino acid-based hydrogels have received widespread attention because of their wide range of sources, biodegradability, and biocompatibility. Despite considerable progress, the development of such ...hydrogels has been limited by critical problems such as bacterial infection and complex preparation. Herein, by using the non-toxic gluconolactone (GDL) to adjust the pH of the solution to induce the rapid self-assembly of N-(benzyloxy)carbonyl-L-tryptophan (ZW) to form a three-dimensional (3D) gel network, we developed a stable and effective self-assembled small-molecule hydrogel. Characterization assays and molecular dynamics studies indicate that π-π stacking and hydrogen bonding are the main drivers of self-assembly between ZW molecules. In vitro experiments further confirmed this material's sustained release properties, low cytotoxicity, and excellent antibacterial activity, particularly against Gram-negative
and Gram-positive
. This study provides a different and innovative perspective for the further development of antibacterial materials based on amino acid derivatives.
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The reuse of construction and demolition waste as a substitute for natural coarse aggregate in the production of recycled concrete has been widely used. In order to study the capillary water ...absorption performance of waterborne-polyurethane-modified recycled aggregate concrete (WPUMRC), the effects of different curing systems, polymer-cement ratios, and waterborne polyurethane addition methods on the cumulative water absorption and the rate of capillary water absorption of WPUMRC were analyzed, and through MIP tests, the micro modification mechanism of waterborne polyurethane in recycled concrete was analyzed. The results indicate that the optimal curing system for both DC (waterborne polyurethane is added separately from water) and HC (waterborne polyurethane is mixed with some effective water and then added) is the 14 d standard curing—14 d indoor natural drying curing system. Waterborne polyurethane can fill the pores and micro-cracks inside WPUMRC or interweave with the hydration products of cement to form a spatial network structure, reducing the porosity, and thereby improving the capillary water absorption performance of WPUMRC. Based on the MIP test results, the grey correlation method was used to establish the relationship between capillary water absorption and the pore structure of WPUMRC under the optimal curing system. In addition, the prediction model of capillary water absorption in recycled concrete was established according to the test results, which can be used to predict WPUMRC’s capillary water absorption performance.
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Ultrahigh-performance concrete (UHPC) has been applied in practical engineering owing to its good workability and high crack resistance. Rational design for UHPC is necessary for optimizing its ...performance. Thus, in the present study, a multi-factor interaction analysis was conducted to identify the optimal mix proportion of UHPC according to an orthogonal design, and then the properties of the optimized UHPC were evaluated. Multi-performance and multi-levels were introduced in the orthogonal design, and the optimization level range of each factor was determined by combining a range and variance analysis with a multi-factor interaction analysis. The mix proportion for the test was determined within the optimized variation range of each factor following the requirements of performance. Subsequently, the workability, mechanical properties, durability, and microstructure of the optimized UHPC were investigated. The results indicated that the fluidity, compressive strength, and flexural strength of the UHPC based on the optimized mix proportion were significantly improved. The optimized UHPC had higher resistances to chloride ion penetration and long-term drying shrinkage than ordinary concrete. Moreover, hot water curing significantly accelerated the hydration process of UHPC. As the curing age increases, hydration products fill the internal pores, and the UHPC paste becomes denser. The pores distributed in the interfacial transition zone between the steel fibers and paste are gradually filled by the hydration products. Thus, the bond performance between the steel fibers and paste is improved.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
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