Development, Characterization and Modeling of Self-healing Cementitious Materials

Cracking is known as the main challenge for the life-cycle performance of concrete. However, the difficulty and cost of repair and maintenance would significantly increase when the cracks are invisible to the raw eyes or inaccessible for human. Therefore, utilizing a self-healing system seems to be an innovative and promising alternative. This work studied the healing performances and influences of two types of abiotic self-healing systems, i.e. urea-formaldehyde (UF) microcapsules and encapsulated impregnated lightweight aggregates (LWAs).We hypothesized that UF microcapsules should have the potential of mitigating the early-age shrinkage and enhancing the freeze-thaw resistance of cement mortar and cement concrete, respectively. Moreover, the LWAs impregnated with saturated Ca(OH)2 solution should be capable of healing the cracks of cement mortar due to bending. Thus, we conducted a series of tests and characterizations to validate our hypotheses and realize the potential of these two self-healing systems.The UF microcapsules exhibit good performance in mitigating the total shrinkage of cement mortar during the 35-day curing period. With the aid of polyvinyl alcohol (PVA) microfibers, the mitigating performance could be further improved. Moreover, this self-healing system could reduce the gas permeability of cement mortar. The scanning electron microscopic observation confirms the healing behavior and validates the chemical composition of healing products. Besides, the UF microcapsules could significantly enhance the durability of cement concrete subjected to freeze-thaw cycles. The 3-D X-ray microcomputed tomography (CT) reveals the enhancing mechanism. We developed a probabilistic damage model based on Weibull distribution and the predicted service life of such self-healing concrete is extended 10 times.Based on the response surface method, the LWAs impregnated with saturated Ca(OH)2 solution are encapsulated by modified PVA films with the optimal designs. The mechanical regain of cement mortar with/without LWAs is determined through three-point bending test. According to the experimental results, the relationship between the mechanical regain and healing period is proposed based on fracture mechanics.To fully validate these models, the test of relative dynamic modulus of elasticity till the failure of concrete and mechanical regain after a longer healing period will be conducted in the future

Obesity contributes to hepatocellular carcinoma development via immunosuppressive microenvironment remodeling

It is generally recognized that the initiation of obesity-related hepatocellular carcinoma (HCC) is closely associated with hepatic inflammation. However, the paradoxical role of inflammation in the initiation and progression of HCC is highlighted by the fact that the inflammatory HCC is accompanied by significant immune effector cells infiltration compared to non-inflammatory HCC and HCC with enhanced immune response exhibits better survival. Importantly, the cancer progression has been primarily attributed to the immunosuppression, which can also be induced by obesity. Furthermore, the increased risk of viral infection and thus viral-HCC in obese individuals supports the view that obesity contributes to HCC via immunosuppression. Here, we have reviewed the various mechanisms responsible for obesity-induced tumor immune microenvironment and immunosuppression in obesity-related HCC. We highlight that the obesity-induced immunosuppression originates from lipid disorder as well as metabolic reprogramming and propose potential therapeutic strategy for HCC based on the current success of immunotherapy

Accelerated Laboratory Assessment of Discrete Sacrificial Anodes for Rehabilitation of Salt-Contaminated Reinforced Concrete

For patch repairs of chloride contaminated RC structures, the use of discrete sacrificial anodes (DSAs) is indispensable. Without DSAs embedded, due to the ring effect, the failure of the RC around the patch area is accelerated. DSAs are increasingly being used, but few studies have evaluated the effectiveness of different DSAs and effects of the surrounding environment on the performance of different DSAs. This study employed four electrical parameters and electrochemical impedance spectroscopy (EIS) to evaluate three types of DSAs embedded in chloride-contaminated concrete through wet–dry and freeze–thaw cycles. The corrosion of the reinforcements is a stochastic process and the bound chloride ions play an important role in determining the corrosion state of the reinforcement. Most of the DSAs provided effective cathodic protection, but the effectiveness of DSAs could be influenced by the corrosion state of the reinforcement. The wet–dry and freeze–thaw cycles had significant influence on the performance of two types of the DSAs. Current DSA designs do not fully utilize the embedded Zn alloy

Preparation process optimization and evaluation of bioactive peptides from Carya cathayensis Sarg meal

Carya cathayensis Sarg meal (CM) is a by-product of the edible kernel during oil manufacture. In order to improve wastes utilization, the CM derived peptides (CMPs) that showed an in vitro radical scavenging ability were firstly prepared by five different hydrolases. Alcalase treatment revealed the highest yield and the optimal conditions were further determined by response surface methodology (RSM), under which the yield reached 35.84%. Simulated gastrointestinal digestion led to an enrichment of low molecular weight (MW) peptides (<3 kDa), which was beneficial for protecting hepatocyte damaged by hydrogen peroxide (H2O2). Furthermore, generated hydrolysates exhibited protective effects on paraquat-induced Caenorhabditis elegans via enhancing expressions of Skinhead-1 (SKN-1) and its downstream target including glutathione S-transferase (GST)-4 and superoxide dismutase (SOD)-3 to diminish oxidative stress. Taken together, our results demonstrated that simple enzymatic hydrolysis of crude protein powder from CM represents an efficient, eco-friendly and economical strategy for producing bioactive peptides, which can be supplemented in nutraceutical products and food preservation

A review of WAAM for steel construction – Manufacturing, material and geometric properties, design, and future directions

This paper provides a review of the capabilities of WAAM for manufacturing steel components for use in the construction industry, with a focus on the structural stability and design of WAAM builds. Manufacturing techniques that can be used for WAAM construction are first discussed. This is followed by a detailed review of the material and geometric properties, and the resulting structural stability performance of WAAM steel structures to date. To exploit the advantage of WAAM in building free-form shapes, structural optimisation techniques suitable for WAAM construction are discussed. Lastly, conclusions and future research directions are provided

Catalytic condensation of phenol with formaldehyde into BPF on recyclable anchoring sulfuric acid

A novel solid-acid catalyst (PVC-EDA-SO4H) based on polyvinyl chloride (PVC) were prepared after amination of Ethylenediamine (EDA) and anchorage of sulfuric acid. The as-prepared catalyst was characterized by FT-IR, Element analysis, Chemical titration and Thermal analysis, the results indicated that the sulfuric acid was successfully anchored on PVC. The PVC-EDA-SO4H showed excellent catalytic performance for the synthesis of bisphenol F, and achieved almost high yield and selectivity (94%) of BPF under the mind reaction conditions. Meanwhile, exhibited excellent reusability without the significant loss after six cycles via simple filtration