STW-MD: a novel spatio-temporal weighting and multi-step decision tree method for considering spatial heterogeneity in brain gene expression data.

Gene expression during brain development or abnormal development is a biological process that is highly dynamic in spatio and temporal. Previous studies have mainly focused on individual brain regions or a certain developmental stage. Our motivation is to address this gap by incorporating spatio-temporal information to gain a more complete understanding of brain development or abnormal brain development, such as Alzheimer's disease (AD), and to identify potential determinants of response. In this study, we propose a novel two-step framework based on spatial-temporal information weighting and multi-step decision trees. This framework can effectively exploit the spatial similarity and temporal dependence between different stages and different brain regions, and facilitate differential gene analysis in brain regions with high heterogeneity. We focus on two datasets: the AD dataset, which includes gene expression data from early, middle and late stages, and the brain development dataset, spanning fetal development to adulthood. Our findings highlight the advantages of the proposed framework in discovering gene classes and elucidating their impact on brain development and AD progression across diverse brain regions and stages. These findings align with existing studies and provide insights into the processes of normal and abnormal brain development.

PAFAH2 suppresses synchronized ferroptosis to ameliorate acute kidney injury.

Synchronized ferroptosis contributes to nephron loss in acute kidney injury (AKI). However, the propagation signals and the underlying mechanisms of the synchronized ferroptosis for renal tubular injury remain unresolved. Here we report that platelet-activating factor (PAF) and PAF-like phospholipids (PAF-LPLs) mediated synchronized ferroptosis and contributed to AKI. The emergence of PAF and PAF-LPLs in ferroptosis caused the instability of biomembranes and signaled the cell death of neighboring cells. This cascade could be suppressed by PAF-acetylhydrolase (II) (PAFAH2) or by addition of antibodies against PAF. Genetic knockout or pharmacological inhibition of PAFAH2 increased PAF production, augmented synchronized ferroptosis and exacerbated ischemia/reperfusion (I/R)-induced AKI. Notably, intravenous administration of wild-type PAFAH2 protein, but not its enzymatically inactive mutants, prevented synchronized tubular cell death, nephron loss and AKI. Our findings offer an insight into the mechanisms of synchronized ferroptosis and suggest a possibility for the preventive intervention of AKI.

In vivo tracking of mesenchymal stem cell dynamics and therapeutics in LPS-induced acute lung injury models.

Mesenchymal stem cells (MSCs) have been widely used to treat various inflammatory and immune-related diseases in preclinical and clinical settings. Intravital microscopy (IVM) is considered the gold standard for investigating pathophysiological conditions in living animals. However, the potential for real-time monitoring of MSCs in the pulmonary microenvironment remains underexplored. In this study, we first constructed a lung window and captured changes in the lung at the cellular level under both inflammatory and noninflammatory conditions with a microscope. We further investigated the dynamics and effects of MSCs under two different conditions. Meanwhile, we assessed the alterations in the adhesive capacity of vascular endothelial cells in vitro to investigate the underlying mechanisms of MSC retention in an inflammatory environment. This study emphasizes the importance of the "lung window" for live imaging of the cellular behavior of MSCs by vein injection. Moreover, our results revealed that the upregulation of vascular cell adhesion molecule 1 (VCAM1) in endothelial cells post-inflammatory injury could enhance MSC retention in the lung, further ameliorating acute lung injury. In summary, intravital microscopy imaging provides a practical method to investigate the therapeutic effects of MSCs in acute lung injury.

Critical Review of Emerging Pre-metallization Technologies for Rechargeable Metal-Ion Batteries.

Low Coulombic efficiency, low-capacity retention, and short cycle life are the primary challenges faced by various metal-ion batteries due to the loss of corresponding active metal. Practically, these issues can be significantly ameliorated by compensating for the loss of active metals using pre-metallization techniques. Herein, the state-of-the-art development in various pr-emetallization techniques is summarized. First, the origin of pre-metallization is elaborated and the Coulombic efficiency of different battery materials is compared. Second, different pre-metallization strategies, including direct physical contact, chemical strategies, electrochemical method, overmetallized approach, and the use of electrode additives are summarized. Third, the impact of pre-metallization on batteries, along with its role in improving Coulombic efficiency is discussed. Fourth, the various characterization techniques required for mechanistic studies in this field are outlined, from laboratory-level experiments to large scientific device. Finally, the current challenges and future opportunities of pre-metallization technology in improving Coulombic efficiency and cycle stability for various metal-ion batteries are discussed. In particular, the positive influence of pre-metallization reagents is emphasized in the anode-free battery systems. It is envisioned that this review will inspire the development of high-performance energy storage systems via the effective pre-metallization technologies.

Subconjunctival Administration of Mesenchymal Stem Cells Alleviates Ocular Inflammation in a Murine Model of Corneal Alkali Burn.

Corneal alkali burns cause extensive damage not only to the cornea but also to the intraocular tissues. As an anti-inflammatory therapy, subconjunctival administration of mesenchymal stem cells (MSCs) for corneal protection after corneal alkali burn has been explored. Little evidence demonstrates the potential of subconjunctival MSCs delivery in protecting the post-burn intraocular tissues. This study aimed to evaluate the therapeutic efficacy of subconjunctival injection of human placental (hP)-MSCs in protecting against ocular destruction after the burn. hP-MSCs were subconjunctivally administered to C57/BL mice after corneal alkali burn. Western blot of iNOS and CD206 was performed to determine the M1 and M2 macrophage infiltration in the cornea. Infiltration of inflammatory cells in the anterior uvea and retina was analyzed by flow cytometry. The TUNEL assay or Western blot of Bax and Bcl2 was used to evaluate the anti-apoptotic effects of MSCs. MSCs could effectively facilitate cornea repair by suppressing inflammatory cytokines IL-1ß, MCP-1, and MMP9, and polarizing CD206 positive M2 macrophages. Anterior uveal and retinal inflammatory cytokines expression and inflammatory cell infiltration were inhibited in the MSC-treated group. Reduced TUNEL positive staining and Bax/Bcl2 ratio indicated the anti-apoptosis of MSCs. MSC-conditioned medium promoted human corneal epithelial cell proliferation and regulated LPS-stimulated inflammation in RAW 264.7 macrophages, confirming the trophic and immunoregulatory effects of MSCs. Our findings demonstrate that subconjunctival administration of MSCs exerted anti-inflammatory and anti-apoptotic effects in the cornea, anterior uvea, and retina after corneal alkali burn. This strategy may provide a new direction for preventing post-event complications after corneal alkali burn.

Ferroptosis: a promising candidate for exosome-mediated regulation in different diseases.

Ferroptosis is a newly discovered form of cell death that is featured in a wide range of diseases. Exosome therapy is a promising therapeutic option that has attracted much attention due to its low immunogenicity, low toxicity, and ability to penetrate biological barriers. In addition, emerging evidence indicates that exosomes possess the ability to modulate the progression of diverse diseases by regulating ferroptosis in damaged cells. Hence, the mechanism by which cell-derived and noncellular-derived exosomes target ferroptosis in different diseases through the system Xc-/GSH/GPX4 axis, NAD(P)H/FSP1/CoQ10 axis, iron metabolism pathway and lipid metabolism pathway associated with ferroptosis, as well as its applications in liver disease, neurological diseases, lung injury, heart injury, cancer and other diseases, are summarized here. Additionally, the role of exosome-regulated ferroptosis as an emerging repair mechanism for damaged tissues and cells is also discussed, and this is expected to be a promising treatment direction for various diseases in the future. Video Abstract.

Surface Engineering of Migratory Corrosion Inhibitors: Controlling the Wettability of Calcium Silicate Hydrate in the Nanoscale.

Migratory corrosion inhibitors (MCIs) are regarded as effective additives to prevent harmful ion transmission and improve concrete durability, but their behavior in the porosity of concrete is still unclarified. This paper proposes a unique perspective to evaluate the effects of surfactant-like MCIs in calcium silicate hydrate (C-S-H) nanoporosity through molecular and electronic structural information. Advanced enhanced sampling methods and perturbation theory methods were applied to evaluate the role of different MCIs. The reduced density gradient of MCI molecules was obtained by using quantum chemical calculations. This calculation is instrumental in elucidating the intensity of interactions among distinct MCI molecule head groups and the C-S-H matrix. It is found that MCIs can effectively improve the interfacial tension (IFT) between C-S-H and water, which corresponds to the inhibitory ability of transmission. Free energy indicates that the MCI has the properties of strong adsorption and weak dissolution, facilitating the improvement of IFT. The relationship between the MCI functional group and the ability of adsorption and dissolution is revealed. This study suggests that MCIs work as surface controllers of C-S-H pores and that their properties can be assessed on the nanoscale.

Enhancement of hair growth through stimulation of hair follicle stem cells by prostaglandin E2 collagen matrix.

Prostaglandin metabolism is involved in the regulation of the periodic process of hair follicles. Preliminary research data reported that prostaglandin E2 (PGE2) exhibits potential in hair growth. However, the relevant evidence is still insufficient. Herein, we prepared a PGE2 matrix by conjugating PGE2 with collagen via crosslinkers to avoid rapid degradation of PGE2 molecules in vivo. First, we measured the physical properties of the PGE2 matrix. A mouse model of hair loss was established, and PGE2 matrix subcutaneous injection was applied to evaluate hair growth. Under different treatments with the PGE2 matrix, the morphology of hair follicles, the dynamic expression of hair follicle stem cell markers and key regulators in the hair growth cycle were explored. Our data revealed that the PGE2 matrix increased the proportion of developing hair follicles at the early growth stage. Improvements in hair follicle stem cells, such as Sox9+ and Lgr5+ cells, have also been confirmed as therapeutic effects of PGE2 to stimulate hair follicle growth. Our study indicated that PGE2 exhibits effective roles in hair development during anagen. Furthermore, the results also highlight the potential of the PGE2 delivery system as a novel therapeutic strategy for the treatment of hair disorders in the future.

The sustained PGE2 release matrix improves neovascularization and skeletal muscle regeneration in a hindlimb ischemia model.

BACKGROUND: The promising therapeutic strategy for the treatment of peripheral artery disease (PAD) is to restore blood supply and promote regeneration of skeletal muscle regeneration. Increasing evidence revealed that prostaglandin E2 (PGE2), a lipid signaling molecule, has significant therapeutic potential for tissue repair and regeneration. Though PGE2 has been well reported in tissue regeneration, the application of PGE2 is hampered by its short half-life in vivo and the lack of a viable system for sustained release of PGE2. RESULTS: In this study, we designed and synthesized a new PGE2 release matrix by chemically bonding PGE2 to collagen. Our results revealed that the PGE2 matrix effectively extends the half-life of PGE2 in vitro and in vivo. Moreover, the PGE2 matrix markedly improved neovascularization by increasing angiogenesis, as confirmed by bioluminescence imaging (BLI). Furthermore, the PGE2 matrix exhibits superior therapeutic efficacy in the hindlimb ischemia model through the activation of MyoD1-mediated muscle stem cells, which is consistent with accelerated structural recovery of skeletal muscle, as evidenced by histological analysis. CONCLUSIONS: Our findings highlight the chemical bonding strategy of chemical bonding PGE2 to collagen for sustained release and may facilitate the development of PGE2-based therapies to significantly improve tissue regeneration.

In vivo two-photon microscopy reveals the contribution of Sox9+ cell to kidney regeneration in a mouse model with extracellular vesicle treatment.

Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) have been shown to stimulate regeneration in the treatment of kidney injury. Renal regeneration is also thought to be stimulated by the activation of Sox9+ cells. However, whether and how the activation mechanisms underlying EV treatment and Sox9+ cell-dependent regeneration intersect is unclear. We reasoned that a high-resolution imaging platform in living animals could help to untangle this system. To test this idea, we first applied EVs derived from human placenta-derived MSCs (hP-MSCs) to a Sox9-CreERT2; R26mTmG transgenic mouse model of acute kidney injury (AKI). Then, we developed an abdominal imaging window in the mouse and tracked the Sox9+ cells in the inducible Sox9-Cre transgenic mice via in vivo lineage tracing with two-photon intravital microscopy. Our results demonstrated that EVs can travel to the injured kidneys post intravenous injection as visualized by Gaussia luciferase imaging and markedly increase the activation of Sox9+ cells. Moreover, the two-photon living imaging of lineage-labeled Sox9+ cells showed that the EVs promoted the expansion of Sox9+ cells in kidneys post AKI. Histological staining results confirmed that the descendants of Sox9+ cells contributed to nephric tubule regeneration which significantly ameliorated the renal function after AKI. In summary, intravital lineage tracing with two-photon microscopy through an embedded abdominal imaging window provides a practical strategy to investigate the beneficial functions and to clarify the mechanisms of regenerative therapies in AKI.

Identification of Hub Genes Associated with Hypertension and Their Interaction with miRNA Based on Weighted Gene Coexpression Network Analysis (WGCNA) Analysis.

BACKGROUND Hypertension is one of the most widespread health conditions in the world, and the molecular mechanism of it is still unclear. In this study, we identified the hub genes (hub miRNA genes) associated with hypertension and explored the relationship between hypertension miRNA-gene by constructing a mRNA co-expression network and a miRNA co-expression network, which can help to reveal the mechanism and predict the prognosis of hypertension progression. MATERIAL AND METHODS Based on gene expression profile data of hypertensive samples from the Gene Expression Omnibus database, WGCNA was used to detect hypertension-related biomarkers and key mRNA and miRNA modules. Then, DAVID was used to perform gene-annotation enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) and miRPath were used for pathway analysis of mRNA and miRNAs genes. RESULTS We identified 3 key modules relating to hypertension, 2 mRNA modules named Msaddlebrown and Mgreenyellow and 1 miRNA module named Msalmon. In addition, 12 hub genes (RPL21, RPS28, LOC442727/PTGAP10, LOC100129599/RPS29P14, TBXAS1, FCER1G, CFP, FURIN, PECAM1, IGSF6, NCF1C, and LOC285296/UNC93B3) and 7 hub miRNAs (hsa-miR-1268a/b, hsa-miR-513c-3p, hsa-miR-4799-5p, hsa-miR-296-3p, hsa-miR-5195-5p, hsa-miR-219-2-3p, and hsa-miR-548d-5p) relating to hypertension were identified. HIF-1 signaling pathway and insulin signaling pathway were closely related to the 3 key modules. We also discovered 4 miRNAs (hsa-miR-548am-3p, hsa-miR-513c-3p, hsa-miR-182-5p, and hsa-miR-548d-5p) and 6 genes (IGF1R, GSK3B, FOXO1, PRKAR2B, HIF1A, and PIK3R1) were the core nodes in the hypertension-related miRNA-gene network, and hsa-miR-548am-3p was at the center of the network. CONCLUSIONS These findings will help improve the understanding of the pathogenesis of hypertension, and the discovered genes can serve as signatures for early diagnosis of hypertension.

Stat3 activation is critical for pluripotency maintenance.

Signal transducer and activator of transcription 3 (Stat3) is a cytoplasmic transcription with many important functions, including regulation of cell proliferation, differentiation, survival, angiogenesis, and immune response. Besides, it plays critical roles in regulating the pluripotency. With the ability of self-renewal and differentiation, embryonic stem (ES) cells provide an unlimited source for cell transplantation. ES cells can maintain its undifferentiated state with leukemia inhibitory factor, the role which is achieved by the activation of the Stat3 pathway. Moreover, Stat3 activation is necessary for the naïve state maintenance of the ES cells and somatic stem cells reprogramming. This study presents an overview of the critical roles of Stat3 activation in the pluripotency maintenance of ES cells, somatic cell reprogramming, and naïve-primed pluripotent states conversion of ES cells.

Dppa3 in pluripotency maintenance of ES cells and early embryogenesis.

Embryonic development is precisely regulated by a network of signal pathways and specific genes. Dppa3 (also known as Pgc7 or Stella) plays an important role in early embryonic development during the cleavage stage as a maternal effect gene. Dppa3 expresses in many species, and its homologous gene in human and rat genomes is located at the same chromosomal regions and have the same exon-intron structure. However, unlike mouse embryonic stem (ES) cells, in which the Dppa3 promoter maintains hypomethylation that allows a high transcription level, the DPPA3 promoter region in human ES cells is methylated, much like that of mouse epiblast stem cell. Dppa3 is essential for early embryogenesis and pluripotency maintenance; however, the precise mechanism and downstream passage remains unknown. In this review, we will summarize some important functions of Dppa3 in early embryogenesis and pluripotency maintenance of mouse ES cells.

Exosomes from mesenchymal stromal cells enhance imatinib-induced apoptosis in human leukemia cells via activation of caspase signaling pathway.

BACKGROUND AIMS: Imatinib (IM), a tyrosine kinase inhibitor targeting the BCR-ABL oncoprotein, remains a major therapeutic strategy for patients with chronic myelogenous leukemia (CML). However, IM resistance is still a challenge in the treatment of CML. Recently, it was reported that exosomes (Exo) were involved in drug resistance. Therefore, the present study investigated whether Exo secreted by human umbilical cord mesenchymal stromal cells (hUC-MSC-Exo) affected the sensitivity of K562 cells to IM. METHODS: hUC-MSC-Exo were isolated and identified. K562 cells were then treated or not with IM (1 µmol/L) in combination with hUC-MSC-Exo (50 µg/mL). Cell viability and apoptosis were determined by cell counting kit 8 (CCK-8) and annexin V/propidium iodide (PI) double staining, respectively. Apoptotic proteins, caspase and their cleaved forms were detected by Western blot. RESULTS: It was shown that hUC-MSC-Exo alone had no effect on cell viability and apoptosis of K562 cells. However, hUC-MSC-Exo promoted IM-induced cell viability inhibition and apoptosis. Moreover, hUC-MSC-Exo enhanced the increased Bax expression and the decreased Bcl-2 expression that were induced by IM. Compared with IM alone, caspase-9 and caspase-3 were further activated by combination of hUC-MSC-Exo with IM. Finally, the effects of hUC-MSC-Exo on K562 cells could be reversed by pretreatment of K562 cells with caspase inhibitor Z-VAD-FMK (30 µmol/L) DISCUSSION: These results indicate that hUC-MSC-Exo enhanced the sensitivity of K562 cells to IM via activation of caspase signaling pathway. Therefore, combining IM with hUC-MSC-Exo could be a promising approach to improve the efficacy of CML treatment.

Molecular Imaging of Inducible VEGF Expression and Tumor Progression in a Breast Cancer Model.

BACKGROUND: Tumor derived vascular endothelial growth factor (VEGF) can stimulate proliferation and migration of endothelial cells and recruit endothelial progenitor cells into tumors for vascular formation via a paracrine manner. Now increasing evidence suggests that VEGF also serves as an autocrine factor promoting cell survival and tumor angiogenesis. Real time visualization of VEGF activity in the early stages of tumor formation using molecular imaging will provide unprecedented insight into the biological processes of cancer. METHODS: The mouse breast cancer cell line 4T1 was transfected with an inducible, bidirectional tetracycline (Bi-Tet) promoter driving VEGF and renilla luciferase (Rluc). This was used to quantitatively image conditional switching of VEGF by bioluminescence imaging (BLI) under the control of systemic administration of doxycycline. Simultaneously, 4T1 cells were labelled with the double fusion reporter gene (Fluc-eGFP) to establish a breast cancer model. RESULTS: We found that inducible VEGF could promote proliferation and attenuate apoptosis due to oxidative stress in an autocrine manner in vitro. In vivo studies revealed that induction of VEGF expression during early tumor development not only dramatically enhanced tumor growth but also increased tumor angiogenesis as visualized by BLI. Finally, immunohistochemistry staining confirmed that inducing VEGF expression promoted cell survival and tumor neovascularization. CONCLUSION: Together the inducible bidirectional tetracycline (Bi-Tet) co-expression system combined with the dual bioluminescence imaging (BLI) system provides a platform to investigate a target gene's role in the pathologic process of cancer and facilitates noninvasive monitoring of biological responses in real time.

Molecular Simulation of the Ions Ultraconfined in the Nanometer-Channel of Calcium Silicate Hydrate: Hydration Mechanism, Dynamic Properties, and Influence on the Cohesive Strength.

Reactive force field molecular dynamics was utilized to investigate the structure, dynamics, and mechanical nature of different cations solvated in the nanometer-channel of highly disordered calcium silicate hydrate. The local structures of different cations bonded with hydroxyl groups are characterized by the long spatial correlation, bond angel distribution preference, and featured coordinated number, resembling those of the tetra-/penta-/octahedron for cation-oxygen structure in the defective region of the silicate glass. Al atoms in the interlayer region play a role in bridging the defective silicate chains and enhance the connectivity of the silicate skeleton. Dynamically, the mobility of ultraconfined water molecules and cations is significantly influenced by the ionic chemistry: the residence time for water molecules in the hydration shell of Al and Mg ions is longer than that in the environment of Na and Ca ions. Furthermore, uniaxial tension simulation provides insight that while both the stiffness and cohesive strength of the C-S-H gels are significantly improved due to the silicate-aluminate branch structure formation, sodium ions with unstable Na-O connection weaken the loading resistance of the C-S-H gels. During the tensile process, the hydrolytic reaction is also affected by the cationic type: water molecules coordinated with Al and Mg cations at high stress state are likely to decompose, but those aggregated with sodium ions are hard to be stretched broken due to the low failure stress.

IGF-1 C Domain-Modified Hydrogel Enhances Cell Therapy for AKI.

Low cell retention and engraftment after transplantation limit the successful application of stem cell therapy for AKI. Engineered microenvironments consisting of a hydrogel matrix and growth factors have been increasingly successful in controlling stem cell fate by mimicking native stem cell niche components. Here, we synthesized a bioactive hydrogel by immobilizing the C domain peptide of IGF-1 (IGF-1C) on chitosan, and we hypothesized that this hydrogel could provide a favorable niche for adipose-derived mesenchymal stem cells (ADSCs) and thereby enhance cell survival in an AKI model. In vitro studies demonstrated that compared with no hydrogel or chitosan hydrogel only, the chitosan-IGF-1C hydrogel increased cell viability through paracrine effects. In vivo, cotransplantation of the chitosan-IGF-1C hydrogel and ADSCs in ischemic kidneys ameliorated renal function, likely by the observed promotion of stem cell survival and angiogenesis, as visualized by bioluminescence imaging and attenuation of fibrosis. In conclusion, IGF-1C immobilized on a chitosan hydrogel provides an artificial microenvironment for ADSCs and may be a promising therapeutic approach for AKI.

The role of Hath6, a newly identified shear-stress-responsive transcription factor, in endothelial cell differentiation and function.

The key regulators of endothelial differentiation that is induced by shear stress are mostly unclear. Human atonal homolog 6 (Hath6 or ATOH8) is an endothelial-selective and shear-stress-responsive transcription factor. In this study, we sought to elucidate the role of Hath6 in the endothelial specification of embryonic stem cells. In a stepwise human embryonic stem cell to endothelial cell (hESC-EC) induction system, Hath6 mRNA was upregulated synchronously with endothelial determination. Subsequently, gain-of-function and loss-of-function studies of Hath6 were performed using the hESC-EC induction model and endothelial cell lines. The overexpression of Hath6, which mimics shear stress treatment, resulted in an increased CD45(-)CD31(+)KDR(+) population, a higher tubular-structure-formation capacity and increased endothelial-specific gene expression. By contrast, the knockdown of Hath6 mRNA markedly decreased endothelial differentiation. Hath6 also facilitated the maturation of endothelial cells in terms of endothelial gene expression, tubular-structure formation and cell migration. We further demonstrated that the gene encoding eNOS is a direct target of Hath6 through a reporter system assay and western blot analysis, and that the inhibition of eNOS diminishes hESC-EC differentiation. These results suggest that eNOS plays a key role in linking Hath6 to the endothelial phenotype. Further in situ hybridization studies in zebrafish and mouse embryos indicated that homologs of Hath6 are involved in vasculogenesis and angiogenesis. This study provides the first confirmation of the positive impact of Hath6 on human embryonic endothelial differentiation and function. Moreover, we present a potential signaling pathway through which shear stress stimulates endothelial differentiation.

Confined Water Dissociation in Disordered Silicate Nanometer-Channels at Elevated Temperatures: Mechanism, Dynamics and Impact on Substrates.

The effects of elevated temperature on the physical and chemical properties of water molecules filled in the nanometer-channels of calcium silicate hydrate have been investigated by performing reactive molecular dynamics simulation on C-S-H gel subjected to high temperature from 500 to 1500 K. The mobility of interlayer water molecules is temperature-dependent: with the elevation of temperature, the self-diffusivity of water molecules increases, and the glassy dynamic nature of interlayer water at low temperature transforms to bulk water characteristic at high temperature. In addition, the high temperature contributes to the water dissociation and hydroxyl group formation, and proton exchange between neighboring water molecules and calcium silicate substrate frequently happens. The hydrolytic reaction of water molecules results in breakage of the silicate chains and weakens the connectivity of the ionic-covalent bonds in the C-S-H skeleton. However, the broken silicate chains can repolymerize together to form branch structures to resist thermal attacking.