Cracks in cement concrete composites, whether autogenous or loading-initiated, are almost inevitable and often difficult to detect and repair, posing a threat to safety and durability of concrete infrastructures, especially for those with strict sealing requirements. The sustainable development of infrastructures calls for the birth of self-healing concrete composites, which has the built-in ability to autonomously repair narrow cracks. This paper reviews the fabrication, characterization, mechanisms and performances of autogenous and autonomous healing concretes. Autogenous healing materials such as mineral admixtures, fibers, nanofillers and curing agents, as well as autonomous healing methods such as electrodeposition, shape memory alloys, capsules, vascular and microbial technologies, have been proven to be effective to partially or even fully repair small cracks. As a result, the mechanical properties and durability of concrete infrastructure can be restored to some extent. However, autonomous healing techniques have shown a better performance in healing cracks than most of autogenous healing methods that are limited to healing of cracks having a width narrower than 150 μm. Self-healing concrete with biomimetic features, such as self-healing concrete based on shape memory alloys, capsules, vascular networks or bacteria, is a frontier subject in the field of material science. Self-healing technology provides concrete infrastructures with the ability to adapt and respond to the environment, exhibiting a great potential to facilitate the creation of a wide variety of resilient materials and infrastructures.

Self-healing cement concrete composites for resilient infrastructures: A review

Synthetic materials used in a wide range of applications are prone to damage in the form of cracking/microcracking Catastrophic failure of the materials may occur due to the growth and merging of the microcracks, which results in the reduction of the service life of the materials To avoid these problems and increase the service life, early detection and mending of the microcracks are extremely important Self-healing materials can be utilized in these cases, which have the capability not only to detect cracks early but also to repair cracks automatically These materials will also have the potential to improve material reliability, extend the service life, reduce replacement costs, and improve product safety Due to these attractive features, numerous research studies are conducted every year on the development of self-healing systems This paper summarizes the latest progress in the design and fabrication techniques of self-healing materials through a wide range of materials, including metals, ceramics, concrete, and polymer composites Based on recent research, this article provides an overview of different chemistries and approaches involved in preparing self-healing composites Comparative healing efficiency and related fabrication methods are tabulated Finally, existing problems, gaps, and challenges, and future research directions and opportunities for commercial applications are highlighted

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Progress and challenges in self-healing composite materials

Application of microbial precipitation in self-healing concrete: A review on the protection strategies for bacteria

A novel capsule by poly (ethylene glycol) granulation for self-healing concrete

The brittleness of microcapsule shell greatly restricts its self-healing performance since it is easily ruptured during the mixing process. Based on the heat releasing nature during cement hydration, a novel concept of temperature-adaptive microcapsule (TAM) was proposed, which can exhibit a switchable mechanical property with temperature. In this paper, a series of TAM with polymethylmethacrylate-methacrylate shell and magnesium oxide core was prepared with four designed transition temperature, and were characterised by Fourier transform infrared spectroscopy, nano-indentation tests, scanning electron microscopy, thermalgravity analysis and particle size analysis, which confirmed the success in preparing the TAM. Moreover, the performance of proposed microcapsules in cement was investigated by determining the breakage rate of microcapsule and recovery rate of cement paste under different mixing temperature. The results illustrated that compared to lower mixing temperature, a 75% reduction in breakage rate and a 5% increment in recovery rate was observed in TAM embedded cementitious paste at an elevated mixing temperature. This work should provide a promising approach to improve the performance of microcapsules for self-healing cementitious materials.

Temperature adaptive microcapsules for self-healing cementitious materials

In marine environments, once concrete cracks aggressive ions immediately migrate into the cracks together with sea water and can cause durability problems. In this study, an innovative self-healing agent that can bind the aggressive ions from marine environments and simultaneously promote the self-healing efficiency was designed and encapsulated as artificial aggregates. As the bulk matrix cracks, the artificial aggregates were intersected. The self-healing agent was exposed to the crack surfaces and reacted with synthetic sea water to heal the crack. Experimental results show that the reaction of the healing agent with synthetic sea water and consequently the formation of Friedel's salt, ettringite, and hydrotalcite in cracks leaded to an efficient chemical binding of Cl−, SO42−, and Mg2+ ions in the synthetic sea water. Meanwhile, for cracks with an initial width of 350–450 μm, the closure ratio due to self-healing by the healing agent was approximately 45% during the first 12 h, about 3 times that in the referenced specimens without the healing agent. Therefore, not only the aggressive ions entering into cracks can be chemically bound, but also the further ingress of aggressive ions from synthetic sea water can be hindered by the rapid crack closure due to self-healing.

Artificial aggregates for self-healing of cement paste and chemical binding of aggressive ions from sea water

Oxygen vacancy-rich flower-like nickel cobalt layered double hydroxides for supercapacitors with ultrahigh capacity

Background Hypertensive patients have a younger trend, and studies on the role of genetic factors in hypertension susceptibility have been inconsistent. Aldehyde dehydrogenases 2 (ALDH2) and apolipoprotein E (APOE) are involved in the pathophysiological processes of hypertension. To investigate the relationship of ALDH2 and APOE polymorphisms with hypertension in middle-aged (30–59 years old) and elderly (≥60 years old) persons. Methods Two thousand six hundred and ten hypertensive patients and 1921 controls were included (between 30 and 100 years old). The genotypes of common polymorphisms in APOE and ALDH2 genes (APOE rs429358, rs7412, and ALDH2 rs671) of the subjects were analyzed by polymerase-chain reaction (PCR)-microarray. Statistical analyses (Student’s t-test, Mann–Whitney U-test, χ2 test, and logistic regression analysis) were performed with SPSS v21.0. Results There were 4531 participants (66.60 ± 12.10 years old) in this study, including 3057 (67.5%) males and 1474 (32.5%) females. There were no significant differences in distributions of ALDH2 rs671, APOE rs429358/rs7412 genotypes and alleles between hypertensive patients and controls. Persons with ALDH2 rs671 G/A or A/A genotype were less likely to have hypertension (G/A+A/A vs G/G: gender-, age-, smoking-, and drinking-adjusted OR 0.885, 95% CI 0.785–0.997, P=0.045), while ALDH2 rs671 A/A+APOE rs429358 or rs7412 wild-type genotype may decrease the risk of hypertension. In middle-aged group, ALDH2 rs671 G/A+APOE rs429358 T/C carriers (adjusted OR 0.547, 95% CI 0.350–0.856, P=0.008), and ALDH2 rs671 A/A+APOE rs7412 C/C genotypes (adjusted OR 0.567, 95% CI 0.361–0.891, P=0.014) were less likely to have hypertension. In elderly group, APOE rs7412 T/T carriers were more likely to have hypertension (rs671 T/T vs C/C: adjusted OR 4.755, 95% CI 1.075–21.027, P=0.040; rs671 T/T vs C/C or C/T: adjusted OR 4.734, 95% CI 1.071–20.928, P=0.040). Conclusion Polymorphism–polymorphism interactions of ALDH2 rs671 and APOE rs429358/rs7412 may effect on hypertension susceptibility. Different genotypes comparison shows different roles in middle-aged and elderly people, respectively.

Association of Different Combinations of ALDH2 rs671, APOE rs429358, rs7412 Polymorphisms with Hypertension in Middle-Aged and Elderly People: A Case–Control Study

As atrial fibrosis is the main feature of atrial structural remodeling, inhibiting atrial fibrosis is crucial to the prevention of atrial fibrillation (AF) progression. Research has shown the correlation between abnormal lipid metabolism and AF progression. However, the effect of specific lipids on atrial fibrosis remains unclear. In the present study, we applied ultra-high-performance lipidomics to analyze the lipid profiles in patients with AF and identify phosphatidylethanolamine (PE) as the differential lipid associated with AF. To detect the effect of the differential lipid on atrial fibrosis, we performed the intraperitoneal injection of Angiotensin II (Ang II) to mice to induce atrial fibrosis and supplemented PE in diets. We also treated atrial cells with PE to evaluate the cellular effect of PE. We found that PE supplementation aggravated atrial fibrosis and increased the expression of the fibrosis-related protein in vitro and in vivo. Moreover, we detected the effect of PE on the atrium. We found that PE increased oxidation products and regulated the expression of ferroptosis-related proteins, which could be alleviated by a ferroptosis inhibitor. PE increased peroxidation and mitochondrial damage in vitro, which promoted cardiomyocyte death induced by Ang II. Examination of protein expression in cardiomyocytes indicated that PE triggered ferroptosis and caused cell death to participate in myocardium fibrosis. In summary, our findings demonstrated the differential lipid profiles of AF patients and revealed the potential effect of PE on atrial remodelling, suggesting that inhibition of PE and ferroptosis might serve as a potential therapy to prevent AF progression.

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Phosphatidylethanolamine aggravates Angiotensin II-induced atrial fibrosis by triggering ferroptosis in mice

Background The utilization of donation after circulatory death (DCD) hearts can enlarge the donor pool. However, DCD hearts suffer from serious ischemia/reperfusion injury (IRI). Recent studies found that the activation of NLRP3 inflammasome could play a significant role in organ IRI. Mcc950, which is a novel inhibitor of the NLRP3 inflammasome, can be applied to treat various kinds of cardiovascular diseases. Therefore, we hypothesized that the treatment of mcc950 could protect DCD hearts preserved with normothermic ex vivo heart perfusion (EVHP) against myocardial IRI via inhibiting NLRP3 inflammasome in a rat heart transplantation model of DCD. Methods Donor-heart rats were randomly divided into four groups: Control group; Vehicle group; MP-mcc950 group; and MP + PO-mcc950 group. Mcc950 was added into the perfusate of normothermic EVHP in the MP-mcc950 and MP + PO-mcc950 groups, and was injected into the left external jugular vein after heart transplantation in the MP + PO-mcc950 group. Cardiac functional assessment was performed. The level of oxidative stress, inflammatory response, apoptosis, and NLRP3 inflammasome-associated protein of donor hearts were evaluated. Results The treatment with mcc950 significantly increased the developed pressure (DP), dP/dtmax, and dP/dtmin of the left ventricular of DCD hearts at 90 min after heart transplantation in both MP-mcc950 and MP + PO-mcc950 groups. Furthermore, mcc950 added into perfusate and injected after transplantation in both MP-mcc950 and MP + PO-mcc950 groups significantly attenuated the level of oxidative stress, inflammatory response, apoptosis, and NLRP3 inflammasome compared with the vehicle group. Conclusions Normothermic EVHP combined with mcc950 treatment can be a promising and novel DCD heart preservation strategy, which can alleviate myocardial IRI via inhibiting NLRP3 inflammasome.

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Normothermic ex vivo heart perfusion with NLRP3 inflammasome inhibitor Mcc950 treatment improves cardiac function of circulatory death hearts after transplantation

Zifeng Zeng

Papers

Artificial aggregates for self-healing of cement paste and chemical binding of aggressive ions from sea water

Oxygen vacancy-rich flower-like nickel cobalt layered double hydroxides for supercapacitors with ultrahigh capacity

Association of Different Combinations of ALDH2 rs671, APOE rs429358, rs7412 Polymorphisms with Hypertension in Middle-Aged and Elderly People: A Case–Control Study

Phosphatidylethanolamine aggravates Angiotensin II-induced atrial fibrosis by triggering ferroptosis in mice

Normothermic ex vivo heart perfusion with NLRP3 inflammasome inhibitor Mcc950 treatment improves cardiac function of circulatory death hearts after transplantation