Numerical Simulation of Compressive Mechanical Properties of 3D Printed Lattice-Reinforced Cement-Based Composites Based on ABAQUS.

Research has established that the incorporation of 3D-printed lattice structures in cement substrates enhances the mechanical properties of cementitious materials. However, given that 3D-printing materials, notably polymers, exhibit varying degrees of mechanical performance under high-temperature conditions, their efficacy is compromised. Notably, at temperatures reaching 150 °C, these materials soften and lose their load-bearing capacity, necessitating further investigation into their compressive mechanical behavior in such environments. This study evaluates the compressibility of cement materials reinforced with lattice structures made from polyamide 6 (PA6) across different structural configurations and ambient temperatures, employing ABAQUS for simulation. Six distinct 3D-printed lattice designs with equivalent volume but varying configurations were tested under ambient temperatures of 20 °C, 50 °C, and 100 °C to assess their impact on compressive properties. The findings indicate that heightened ambient temperatures significantly diminish the reinforcing effect of 3D-printed materials on the properties of cement-based composites.

Compressive properties of self-healing microcapsule-based cementitious composites subjected to freeze-thaw cycles using acoustic emission.

Microcapsule self-healing technology is an effective scheme to improve the durability of cementitious composites. In this paper, the compressive properties of microcapsule-based self-healing cementitious composites after freeze-thaw cycles were studied using acoustic emission (AE), and the changes in AE characteristics, compressive strength, mass loss rate, and electric flux of microcapsule-based self-healing cementitious composites with different microcapsule contents and freeze-thaw cycles were studied. The results show that if the content of the microcapsule is appropriate, with the increase in the number of freeze-thaw cycles, the AE hits will generally increase first and then decrease, and the early AE events will also decrease. Because of the different contents of microcapsules, the improvement effect and defect effect change dynamically with the number of freeze-thaw cycles, which is also reflected in the dynamic process of compressive strength. After 100 freeze-thaw cycles, the compressive strength of self-healing cementitious composite samples with 5% content of microcapsules and 3% content of microcapsules is the highest. The changes in mass loss rate and electric flux are similar to the AE characteristic parameters, which further verifies the results of AE. The research results of this paper provide experimental data and experimental methods for the engineering application of microcapsule self-healing cement-based composites in cold areas.

Exploration of ecological restoration of saline-alkali land based on NbS--Study on the salt resistance and desalination performance of three cash crops.

Soil salinization is one of the current global environmental problems. Current research on crops in saline-alkali land focuses on salt tolerance, but less on its ecological benefits. However, plants and the environment can interact and influence each other, which is the theory used to carry out Nature-based Solutions (NbS). Therefore, the research on crop plants with both ecological and economic benefits is novel and valuable work. Then three widely planted cash crops (Solanum melongena, Momordica charantia, Capsicum annuum) were selected for salt stress treatment (NaCl, 150mmol/L), some physiological indicators (chlorophyll, soluble protein, Proline (Pro), malondialdehyde (MDA)) of plant and the soil properties (electrical conductivity, pH, the soil salt content) were measured. The results showed that the salinity content of the three plant cultivation soils was significantly different (P<0.05) after the salt stress; all three crops had some desalination capacity, but Capsicum annuum had the strongest salt resistance and desalination capacity.

Efficacy and Safety of Ganduqing Granules in Treating the Common Cold: A Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial.

Background: There is no clear evidence-based medicine that points to the most effective drug treatments for the common cold. In view of its ability to relieve symptoms and shorten the disease course, as well as its minimal side effects, traditional Chinese medicine (TCM) has been widely used to treat the common cold. However, there is a lack of strong evidence to support the clinical efficacy of TCM. This study aimed to evaluate the efficacy and safety of Ganduqing granules in the treatment of the common cold based on the network pharmacology analysis. Methods: In this multicenter, randomized, double-blind, placebo-controlled trial, 60 eligible subjects will be randomly assigned to either the intervention group or the placebo group. The intervention group will be treated with Ganduqing granules, while the placebo group will be treated with placebo. After 5 days of intervention, the efficacy and safety of Ganduqing granules in the treatment of the common cold will be observed. The primary outcome is the time to clearance of all symptoms. The secondary outcomes included the levels of IL-6, TNF-α, SOD, and MDA in the peripheral blood, time to disappearance of primary symptoms and secondary symptoms, clinical symptom remission rate, and change in TCM syndrome score. Results: Sixty participants completed the study. Ganduqing granules showed a greater effect on the time to clearance of all symptoms (P < 0.0001), nasal discharge (P=0.0124), fatigue and lack of strength (P=0.0138), dryness of the pharynx (P < 0.0001), pharyngalgia or dysphagia (P < 0.0001), and expectoration (P < 0.0431) compared with the placebo group. Participants in the intervention group had a greater decrease of IL-6 levels compared with the placebo group (P < 0.007); similar results were observed for the SOD (P < 0.033). However, the change in TNF-α and MDA levels in the intervention group was not significantly different from the placebo group. In addition, participants in the intervention group had a greater decrease of TCM syndrome score compared with the placebo group (P < 0.040). Conclusion: Ganduqing granules could improve common cold symptoms, shorten the disease course, attenuated inflammation and oxidative stress, and provided objective evidence for the efficacy and safety of a Chinese herbal medicine in treating the common cold.

Effects of Strength and Distribution of SiC on the Mechanical Properties of SiCp/Al Composites.

In this paper, considering the strength and geometric discrete distribution characteristics of composite reinforcement, by introducing the discrete distribution function of reinforcement, the secondary development of ABAQUS is realized by using the Python language, the parametric automatic generation method of representative volume elements of particle-reinforced composites is established, and the tensile properties of silicon carbide particle-reinforced aluminum matrix composites are analyzed. The effects of particle strength, particle volume fraction, and particle random distribution on the mechanical properties of SiCp/Al composites are studied. The results show that the random distribution of particles and the change in particle strength have no obvious influence on the stress-strain relationship before the beginning of material damage, but have a great influence on the damage stage, maximum strength, and corresponding failure strain. With the increase in particle volume fraction, the damage intensity of the model increases, and the random distribution of particles has a great influence on the model with a large particle volume fraction. The results can provide a reference for the design, preparation, and characterization of particle-reinforced metal matrix composites.

Preparation and Mechanical Properties of Microcapsule-Based Self-Healing Cementitious Composites.

Self-healing concrete designs can protect against deterioration and improve durability. However, there is no unified conclusion regarding the effective preparation and mechanical properties of self-healing concrete. In this paper, microcapsules are used in cement-based materials, the reasonable dosage of microcapsules is determined, and the self-healing performance of the microcapsule self-healing system under different curing agents is explored. The microcapsules and curing agent are shown to enhance the flexural and compressive strength of mortar specimens at relatively low contents. The optimal microcapsule content in terms of compressive strength is 1-3%. When the content of the microcapsule reaches 7%, the strength of the specimen decreases by approximately 30%. Sodium fluorosilicate is better-suited to the microcapsule self-healing cement-based system than the other two fluorosilicates, potassium fluorosilicate and magnesium, which have similarly poor healing performance as curing agents. Healing time also appears to significantly influence the microcapsule self-healing system; mortar specimens that healed for 28 days are significantly higher than those that healed for 7 days. This work may provide a valuable reference for the design and preparation of self-healing cementitious composite structures.

Influencing Factors on the Healing Performance of Microcapsule Self-Healing Concrete.

The amounts of the components in a microcapsule self-healing system significantly impact the basic performance and self-healing performance of concrete. In this paper, an orthogonal experimental design is used to investigate the healing performance of microcapsule self-healing concrete under different pre-damage loads. The strength recovery performance and sound speed recovery performance under extensive damage are analyzed. The optimum factor combination of the microcapsule self-healing concrete is obtained. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) are carried out on the concrete samples before and after healing to determine the healing mechanism. The results show that the healing effect of self-healing concrete decreases with an increase in the pre-damage load, and the sound speed recovery rate increases with an increase in the damage degree. The influence of the sodium silicate content on the compressive strength and compressive strength recovery rate of the self-healing concrete increases, followed by a decrease. The optimum combination of factors of the microcapsule self-healing system is 3% microcapsules, 30% sodium silicate, and 15% sodium fluosilicate. The results can be used for the design and preparation of self-healing concrete.

Study of matrix crack-tilted fiber bundle interaction using caustics and finite element method.

In this work, the interaction between the matrix crack and a tilted fiber bundle was investigated via caustics and the finite element method (FEM). First, the caustic patterns at the crack tip with different distances from the tilted fiber were obtained and the stress intensity factors were extracted from the geometry of the caustic patterns. Subsequently, the shielding effect of the fiber bundle in front of the crack tip was analyzed. Furthermore, the interaction between the matrix crack and the broken fiber bundle was discussed. Finally, a finite element simulation was carried out using ABAQUS to verify the experimental results. The results demonstrate that the stress intensity factors extracted from caustic experiments are in excellent agreement with the data calculated by FEM.