Hydration Activity Research Articles

Carbonic Anhydrase 3 is required for cardiac repair post myocardial infarction via Smad7-Smad2/3 signaling pathway.

Appropriate fibrosis is required to prevent subsequent adverse remodeling and heart failure post myocardial infarction (MI), and cardiac fibroblasts (CFs) play a critical role during the process. Carbonic anhydrase 3 (CAR3) is an important mediator in multiple biological processes besides its CO2 hydration activity; however, the role and underlying mechanism of CAR3 on cardiac repair post MI injury remains unknown. Here, we found that CAR3 expression was up-regulated in cardiac tissue in infarct area at the reparative phase of MI, with a peak at 7 days post MI. The upregulation was detected mainly on fibroblast instead of cardiomyocyte, and primary cardiac fibroblasts treated with TGF-β1 recaptured our observation. While CAR3 deficiency leads to weakened collagen density, enlarged infarct size and aggravated cardiac dysfunction post-MI. In fibroblast, we observed that CAR3 deficiency restrains collagen synthesis, cell migration and gel contraction of cardiac fibroblasts, whereas overexpression of CAR3 in CFs improves wound healing and cardiac fibroblast activation. Mechanistically, CAR3 stabilizes Smad7 protein via modulating its acetylation, which dampens phosphorylation of Smad2 and Smad3, thus inhibiting fibroblast transformation. In contrast, inhibition of Smad7 acetylation with C646 blunts CAR3 deficiency induced suppression of fibroblast activation and impaired cardiac healing. Our data demonstrate a protective role of CAR3 in cardiac wound repair post MI via promoting fibroblasts activation through Smad7-TGF-β/Smad2/3 signaling pathway.

Stopped-flow measurement of CO2 hydration activity by catalytic amyloids.

With the ever-increasing rates of catalysis shown by catalytic amyloids, the use of faster characterization techniques is required for proper kinetic studies. The same is true for inherently fast chemical reactions. Carbon dioxide hydration is of significant interest to the field of enzyme design, given both carbonic anhydrases' status as a "perfect enzyme" and the central role carbonic anhydrase plays in the respiration and existence of all carbon-based life. Carbon dioxide is an underexplored hydrolysis substrate within the literature, and a lack of a direct spectroscopic marker for reaction monitoring can make studies more complex and require specialist equipment. Within this article we present a method for measuring the carbon dioxide hydration activity of amyloid fibrils.

Identification and evolution of non-traditional nitrilase from Spirosoma linguale DSM 74 with high hydration activity

Hydration, a secondary activity mediated by nitrilase, is a promising new pathway for amide production. However, low hydration activity of nitrilase or trade-off between hydration and catalytic activity hinders its application in the production of amides. Here, natural C-terminal-truncated wild-type nitrilase, mined from a public database, obtained a high-hydration activity nitrilase as a novel evolutionary starting point for further protein engineering. The nitrilase Nit-74 from Spirosoma linguale DSM 74 was successfully obtained and exhibited the highest hydration activity level, performing 50.7 % nicotinamide formation and 87.6 % conversion to 2 mM substrate 3-cyanopyridine. Steric hindrance of the catalytic activity center and the N-terminus of the catalytic cysteine residue helped us identify three key residues: I166, W168, and T191. Saturation mutations resulted in three single mutants that further improved the hydration activity of N-heterocyclic nitriles. Among them, the mutant T191S performed 72.7 % nicotinamide formation, which was much higher than the previously reported highest level of 18.7 %. Additionally, mutants I166N and W168Y exhibited a 97.5 % 2-picolinamide ratio and 97.7 % isonicotinamide ratio without any loss of catalytic activity, which did not indicate a trade-off effect. Our results expand the screening and evolution library of promiscuous nitrilases with high hydration activity for amide formation.

Enhancing CO2-Cured cementitious binder with Mg-doped γ-C2S from high-Mg limestone

This study explores the use of Mg-doped γ-C2S, an alternative to conventional Portland cement, to address the environmental impact of the cement industry. γ-C2S, known for low hydration activity, shows promise as a CO2-cured binder. The research investigates Mg substitution in γ-C2S synthesis, utilizing high-Mg limestone resources. Varying Mg/Ca ratios in γ-C2S synthesis promoted bredigite and merwinite phases during calcination, enhancing specific surface area by over 40%. Optimal Mg doping significantly increased carbonation reactivity, resulting in a 20% strength boost (115 MPa) after 24h of CO2 curing. This improvement is attributed to enhanced crystallinity in carbonation products, namely hydromagnesite, nesquehonite, aragonite, and magnesite, leading to microstructure densification. The findings highlight Mg-doping as a promising strategy to enhance the carbonation performance of γ-C2S from high-Mg limestone, offering prospects for sustainable construction materials with reduced CO2 emissions.

Expanded titanium-bearing blast furnace slag phase change aggregate: Preparation, performance and phase change energy storage mortar application

Expanded titanium-bearing blast furnace slag (ETS), containing rich connected pores, largely accumulated, due to low hydration activity and particle strength. In this study, the pore system of ETS was fully utilized to load paraffin for fabrication of phase change aggregate (PCA), and then the PCA was used to prepare phase change energy storage mortar (PCEM) and mechanical properties, thermal performances and energy-saving efficiency were subsequently evaluated. The results indicated that the 28-day and 56-day compressive strength of mortar containing 100 % PCA reached to 7.8 MPa and 8.6 MPa. The energy saving efficiency of building reached to 8.1 %, the peak indoor temperature of building decreased by 1.2 °C and 2.3 °C in spring and summer, respectively. These facts give confidence of ETS consumption in building energy-saving materials.

Hydration Activity and Carbonation of the Solid Solution of MgO-FeO-MnO-CaO System in Steel Slag

Hydration Activity and Carbonation of the Solid Solution of MgO-FeO-MnO-CaO System in Steel Slag

Preparation technology and microstructural changes of low-activity magnesium oxide based on salt lake bischofite

In response to the high cost of magnesium phosphate cement (MPC), due to the high production energy consumption of raw material MgO (sintering at 1600 °C for 5 h), and the requirement of adding retarders during the preparation process, we proposed using common elements B, Li, Na, K, and Cl in salt lakes to promote the sintering performance of MgO. We subsequently studied the preparation technology of low-activity MgO obtained from the pyrolysis of bischofite in salt lakes and low-temperature sintering (≤ 1200 °C). The migration law of coexisting elements and low-temperature sintering mechanism of salt lake bischofite was revealed during pyrolysis and low-temperature sintering, expanding the utilization path of salt lake bischofite and promoting resource recycling. We simultaneously developed a preparation technology for low-activity MgO used as raw MPC material, avoiding the use of retarders and reducing the raw material costs in the preparation of MPC. The results showed that coexisting elements migration was present in four different types of processes during the sintering process. Octahedral particles with a preferred orientation and exposed MgO (111) crystal face were obtained. With increased sintering temperature and time, the content and particle size of MgO increased and the specific surface area and porosity decreased, which led to the prolonged neutralization reaction time, as well as increased sintering degree and decrease in hydration activity. The formation of the liquid phase by bischofite and its coexisting elements was the key to MgO sintered at 1000 °C.

Synergistic preparation of high-performance composite blast furnace slag powder from multiple industrial solid wastes: Performance regulation and optimization

Blast furnace slag (BFS) is commonly used as a substitute for cement clinker due to its hydration properties. However, the demand for BFS is outpacing the supply, and its price is rising steadily. Moreover, the significant accumulation of industrial waste with potential hydration properties poses a severe environmental threat. To address these challenges, this paper aimed to prepare high-performance composite blast furnace slag powder (CBFS) by incorporating red mud (RM), fly ash (FA), desulfurization gypsum (DG) and BFS, guided by the synergistic effects and the theory of medium-calcium systems. This paper reveals that the primary activation methods of the amorphous silicon-aluminum mineral phases in CBFS are alkali activation and sulfate activation. The optimal results demonstrate that the compressive strength of CBFS-cementitious material (50% CBFS + 50% cement) can reach 52.8 MPa, meeting the standards of Portland Cement PO 42.5. Additionally, RM, FA and DG account for 66% of CBFS and the hydration activity of CBFS is better than that of S95-grade BFS. Furthermore, the CBFS-cementitious material effectively immobilizes hazardous elements of the raw materials, and the leachate meets drinking water standards. The application of CBFS facilitates the recycling of industrial solid wastes, improves the quality of construction materials and reduces the construction industry's dependence on BFS.

The mechanical strength, microstructure, and transport properties of steel slag reinforced loess soil system

Steel slag, as an industrial byproduct obtained from the steel manufacturing industry, may cause land occupation, resource waste, and environmental pollution. The application of steel slag as a material for soil reinforcement in road engineering is very popular due to its potential hydration activity. The unconfined compression strength, microstructure, and transport properties of loess soil with cement, lime and steel slag were investigated. The results show that the loess soil can be reinforced by cement, lime, and steel slag to varying degrees. The reinforcement mechanism of cement for loess soil is realized by pore filling by cement hydration products such as CH, C-S-H and AFt, and their unconfined compression strength is improved by reducing the porosity. The reinforcement mechanism of lime for loess soil is achieved by pore filling by hydration products such as CH and CaCO3, and their strength is improved by a refined pore structure where the porosity has not been significantly reduced. The reinforcement mechanism of steel slag for loess soil is a combined mechanism of cement and lime, including pore filling and refined pores. The pore structure of reinforced soil can be studied at different scales by the MIP, LF NMR, and X-CT test methods. The transport properties including diffusivity and permeability of reinforcing soil can be well explored by Avizo software based on the microstructure obtained from X-CT.

Increasing the Hydration Activity of Tricalcium Silicate by Adding Microdispersed Ettringite as a Nucleating Agent.

Tricalcium silicate (C3S) as a binder material has a decisive influence on the processes of hardening and strength gain of cements and concretes. One of the promising directions is the introduction of dispersed additives into cement mixtures, which allow micro-level control of the composition of hydration products and change the dynamics of the structure formation of cement stone. In this paper, the effect of a microdisperse ettringite additive on the kinetics of the hydration and hardening process of tricalcium silicate was studied. It was shown that ettringite crystals selectively adsorb Ca2+ and OH- ions from a saturated solution of calcium hydroxide, which contributes to the formation of hydrosilicate nuclei on their surface during cement hydration. Hydration of C3S in the presence of ettringite proceeds more intensively; the addition of ettringite contributes to an increase in the content of calcium hydrosilicates in hydration products at the initial stage of the process. Addition of 10 wt.% ettringite to C3S reduces the induction period of the beginning of the main phase of heat release by around two times and increases the amount of heat released on the 1st day of hydration by 15% compared to the control sample. According to electron microscopy data, it was found that during the first hours of hydration of modified C3S, a significant number of nuclei of fibrous particles of calcium hydrosilicates with sizes of 0.2-2 microns were formed on the surface of ettringite crystals. According to the results of kinetic modeling of the setting process of cement pastes using the Avrami-Erofeyev model, it was shown that in the presence of the addition of microcrystals of ettringite, the setting rate is characterized by a slowdown in nucleation, whereas for a sample without an additive, this process proceeds with an acceleration of the formation of solid-phase nuclei. Based on the comparison of kinetic results and mechanical measurements, it is concluded that needle crystals of ettringite during C3S hydration and cement stone hardening are preformed centers for the growth of hydrosilicate nuclei, and they also act as a reinforcing filler, increasing the bending strength of modified samples. The results of the work can be used in practice in the development of methods for controlling the processes of hydration and hardening of cements, as well as for controllable structure formation of cement stone which is important in particular for 3D printing of building products and constructions.

Metallurgical Waste as a Raw Material Reserve for Achieving Carbon Neutrality of the Construction Industry. Part 1. Ability of Metallurgical Waste to Bind CO2

The solution to global environmental problems is to reduce the anthropogenic impact on the environment through the utilization of carbon dioxide emissions and the use of industrial waste to produce new materials and products. Technogenic wastes of the metallurgical industry are considered as raw materials for the production of building materials and products with the ability to bind gaseous CO2. The analysis and selection of waste from metallurgical enterprises located in the Central and North-Western Federal Districts of the Russian Federation is carried out. The results of studies of environmental friendliness, chemical, material and phase-mineralogical compositions of technogenic metallurgy waste, their hydration activity and ability to bind carbon dioxide are presented. It is shown that the most promising raw materials for the production of building materials and products are steelmaking slags and nepheline sludge from the processing of alumina raw materials. The greatest ability to absorb and bind CO2 is distinguished by nepheline sludge (up to 12% CO2 by weight of sludge), steelmaking (converter and electric steelmaking) slags (up to 8.8 and 9.2% CO2 by weight of slag, respectively). The compressive strength of the prototypes on these types of slags depends on the degree of their carbonation and reaches values of 100 MPa or more after 6 hours of forced carbonation. It is concluded that the material obtained from man-made metallurgical waste by carbonation hardening technology can be used as a matrix substance for various building materials and products.

Preparation and reaction mechanism of low environmental load mud solidification agent from multivariate solid waste

Utilizing various industrial solid waste to replace cement to prepare mud solidification materials could achieve energy conservation, carbon reduction and sustainable development. This research conducted solidification mud (SM) experiments using solidification agent (SA) compounded by mixing five types of solid waste. The focus was on studying the performance of SA and SM in the presence of different activators, as well as the influence of different activators on the SA curing mechanism. The results indicate that the SA and SM specimens with 3.0% Na2SiO3 addition had the highest compressive strength values at 1 d and 28 d, respectively. In addition, the microscopic test analysis showed that when 3.0% Na2SiO3 was added, the hydration activity of SA was relatively high, and the continuous distribution of cluster gel in the hydration product made its overall structure more compact.

Effect of MgO on microstructure evolution and exothermic characteristics of tricalcium aluminate during hydration

The phase composition, microstructure, and hydration process of C3A with different MgO content were compared to elucidate the mechanism of hydration resistance of CaO improved by MgO–C3A solid solution. The process of hydration heat release was detected by isothermal calorimetry and the hydration products were analyzed by X-ray diffraction and scanning electron microscope. The results showed that the addition of MgO resulted in lattice distortion of C3A. In the middle and late stages of the hydration process, Mg(OH)2 and amorphous gel-like substances covered the surface of the unreacted C3A and reduced the hydration reaction rate. The addition of MgO effectively reduced the hydration activity of the MgO–C3A solid solution that indicated the addition of MgO can improve the hydration resistance of CaO materials.

Enhancement of Hydration Activity and Microstructure Analysis of γ-C2S.

This paper investigated the combined effect of chemical activators and nano-SiO2 on the hydration reaction and the microstructure of γ-C2S. The hydration reaction of γ-C2S slurry activated with chemical activators (NaHCO3, NaOH, K2CO3, and KOH at 1 mol/L) was enhanced by 1% nano-SiO2. The hydrate reaction rate was determined by isothermal calorimetry, and the hydrated samples were characterized by XRD, TGA/DTG, SEM-EDS, and 29Si MAS/NMR. The results revealed a substantial enhancement in the hydration activity of γ-C2S due to the presence of the alkaline activator. Furthermore, nano-SiO2 did not alter the composition of γ-C2S hydration products, instead providing nucleation sites for the growth of hydration products. Incorporating nano-SiO2 promoted the formation of C-(R)-S-H gel with a low calcium-to-silica ratio and increased its polymerization levels, resulting in more favorable structures. Among all the activators used in this study, potassium salts had a better activation effect than sodium salts. After 28 days of curing, the degree of hydration reaction in the KC+Si group was 48% and about 37% for the NHC+Si group. Whereas, the KH+Si and NH+Si groups only reached approximately 20% after the same hydration duration.

Cooperation of an external carbonic anhydrase and HCO3- transporter supports underwater photosynthesis in submerged leaves of the amphibious plant Hygrophila difformis.

HCO3- can be a major carbon resource for photosynthesis in underwater environments. Here we investigate the underlying mechanism of uptake and membrane transport of HCO3- in submerged leaves of Hygrophila difformis, a heterophyllous amphibious plant. To characterize these mechanisms, we evaluated the sensitivity of underwater photosynthesis to an external carbonic anhydrase (CA) inhibitor and an anion exchanger protein inhibitor, and we attempted to identify components of the mechanism of HCO3- utilization. We evaluated the effects of the external CA inhibitor and anion exchanger protein inhibitor on the NaHCO3 response of photosynthetic O2 evolution in submerged leaves of H. difformis. Furthermore, we performed a comparative transcriptomic analysis between terrestrial and submerged leaves. Photosynthesis in the submerged leaves was decreased by both the external CA inhibitor and anion exchanger protein inhibitor, but no additive effect was observed. Among upregulated genes in submerged leaves, two α-CAs, Hdα-CA1 and Hdα-CA2, and one β-carbonic anhydrase, Hdβ-CA1, were detected. Based on their putative amino acid sequences, the α-CAs are predicted to be localized in the apoplastic region. Recombinant Hdα-CA1 and Hdβ-CA1 showed dominant CO2 hydration activity over HCO3- dehydration activity. We propose that the use of HCO3- for photosynthesis in submerged leaves of H. difformis is driven by the cooperation between an external CA, Hdα-CA1, and an unidentified HCO3- transporter.

Kill two birds with one stone: Contribution of steel slag on enhancing the performance of coal gangue-based cementitious materials and simultaneous sulfur fixation

The thermal activation of coal gangue (CG) is essential for its application in cement system; however, controlling the sulfur emission and improving the hydration activity to CG during activation are considerably challenging. Steel slag (SS), a potential additive, can simultaneously enhance cementitious material strength while attaining sulfur fixation. This research tries to introduce SS to solve CG dual puzzle and reached “kill two birds with one stone”. The results indicate that the calcination behavior of CG can be divided into three stages, with most calcination occurring in the second stage and calcination inhibited during the main weight loss stage. CG primarily releases sulfur in the form of SO2 and H2S during the combustion. Sample G2S1(CG:SS = 2:1) showed the highest sulfur fixation efficiency, with 67.87% for total sulfur gas, 94.73% for H2S and 66.91% for SO2. SS reduced the required average activation energy by nearly half, indicating that SS has a significant impact on lowering the energy barrier and enhancing the overall activity. Together with sulfur fixation, G2S1 calcined at 600 °C considerably improved the performance of cementitious materials, with the compressive strength reaching 82.67 MPa. The mechanism of achieving the "kill two birds with one stone" objective can be attributed to the introduction of SS, which provides an abundant supply of calcium. On the one hand, it facilitates the sulfur fixation process by forming CaSO4. On the other hand, it contributes to the availability of CaO in the cementitious material, accelerating the formation of C–S–H gel.

Utilization of Coal gasification fine ash for construction material: From physical and chemical properties to the hydration activity of thermally modified CGFA

Coal gasification technology is the core of clean and efficient utilization of coal, while coal gasification fine ash (CGFA) is the solid waste inevitably produced in the coal gasification process. Due to the high residual carbon content and water retention of CGFA, the solubility of its silica-aluminium-calcium-containing minerals is poor, which affects its potential cementing properties in construction materials. In this paper, the basic physicochemical properties were investigated, and it was found that small particles of CGFA (CGFA-S) had more active mineral components, lower residual carbon content (17.17%) and weaker water retention (6.91%), which facilitated the removal of impurities and water. In addition, the best effects were achieved at a heat treatment temperature of 650 °C, which exposed the minerals and increased the solution solubility, and the leaching concentrations of Si4+, Al3+, and Ca2+ increased by 21.2%, 44.6%, and 97.8%, respectively. However, when the temperature was too high (815 °C), the minerals recrystallized, leading to structural instability and dissolution difficulties, and the concentrations of the three major ions were reduced by 84.4%, 82.0%, and 42.2%, respectively, compared with the control.Finally, the optimal heat treatment temperature was 650 °C, with the highest exothermic hydration rate (11.92 mW/g) and the highest cumulative exothermic heat (199.81 J/g). The hydration products were tightly bound, and the cement mortar specimens had the highest compressive strength, with a 28d strength of 45.4 MPa.

Effect of direct electric curing on the mechanical properties, hydration process, and environmental benefits of cement-steel slag composite

Steel slag (SS) is a solid waste produced from the steelmaking process. The weak early hydration activity of steel slag limits its application in cementitious materials. This study attempts to improve the early-age performance of cement-SS composite by direct electric curing (DEC) to broaden the application of SS in cementitious materials. Specifically, The study involves continuous monitoring of performance changes of the specimens over time, with a particular focus on early-age characteristics. The change in strength and capillary water absorption of the hardened paste are evaluated. The pore size distribution and content are investigated by BET, and the effects of DEC on the hydration process of cement-SS composite are determined by XRD, TG, and BSE. The results demonstrate that DEC effectively improves the early-age strength of specimens. The 1d strength of the specimens increased by more than 50% at 50% steel slag dosage. Additionally, DEC effectively reduces the pore size. DEC does not change the type of hydration products of the paste but effectively accelerates the hydration process of the cement-SS composite. This accelerated reaction leads to a notable increase in calcium hydroxide and bound water content at an early age, consequently improving the degree of hydration reaction in steel slag. SEM-BSE analysis revealed changes in the atomic composition of the C-S-H gel near the SS, accompanied by blurred boundaries in the morphology of SS particles. Moreover, this study analyzes the economic and environmental benefits of using cement-steel slag composite with DEC. Considering the strength factor, the cost required to obtain a unit strength by DEC is only 55.88%-71.28% of that required with standard curing method. Simultaneously, carbon emission is reduced by 28.79%-44.16%. Thus, DEC is a sustainable and practical method for promoting the utilization of steel slag in cementitious materials, offering both economic and environmental benefits.

The role of P2O5 on the stability of β-C2S in AOD slag based on the improvement of hydration activity

The original AOD slag in the cold state contained more than 50 wt% low-hydration activity γ-C2S, which significantly affects the hydration activity. Therefore, the effect of the typical crystal stabilizer P2O5 on the formation of a new phase and the enhancement in the mass fraction of high hydration activity β-C2S in AOD slag were studied, and the internal factors that controlled the doping preference and influenced the hydration activity of the crystal stabilizer P2O5 were revealed. When the addition of P2O5 was 0.6 wt%, the mass fraction of β-C2S in AOD slag was increased by 50.8 wt%. The P5+ and its oxide P2O5 entered the lattice of C2S in solid solution, causing lattice distortion. After P doping, the charge energies of the Ca, Si and O atoms shifted toward the low energy direction by approximately 5 eV, which increased the stability of the electronic structure. In addition, P doping changed the delocalization of the CBM in the pure phase, partially located the LDOS of the VBM and CBM, and increased the numbers of nucleophilic and electrophilic attack sites, thus improving the hydration activity of β-C2S.

Effect of Hydroxypropyl methyl cellulose (HPMC) on rheology and printability of the first printed layer of cement activated slag-based 3D printing concrete

Nowadays, Ground Granulated Blast Furnace Slag (GGBFS) is generally used to replace cement for reducing carbon emissions, but due to its low hydration activity and unstable working performance in the early stage, it is difficult to apply in 3D printed concrete (3DPC) as the main binder. In this study, a combination of ordinary Portland cement and calcium sulfoaluminate cement was used to activate GGBFS. In the presence of 0.2 wt% polycarboxylate superplasticizer (PCE), in order to achieve high-precision printing, hydroxypropyl methyl cellulose (HPMC) was used. The rheological properties of mortar were evaluated by the slugs-test and a rotational rheometer. The results show that the yield stress and thixotropy of slag cement-based 3D printing concrete are significantly increased, with addition of HPMC. The slugs-test shows its advantages in measuring rheological properties, such as superior repeatability of rheological data and a better association with 3D printing performance. Pumpability, extrudability, and buildability of the first printed layer of slag cement-based 3DPC were evaluated using pumping pressure, horizontal printing, and vertical printing. The results show that, with a 0.15 wt% HPMC, the 3D printing properties of the first layer are greatly improved, a stable and high-precision slag cement-based 3DPC can be developed, and the relationship between rheological properties and 3D printing performance can be established.