Dendritic mesoporous silica nanoparticles are one of silicon-based mesoporous materials. This material is widely used in various fields due to the special central radial mesoporous channel structure. This review represented recent development on dendritic mesoporous silica nanoparticles, and described the dendritic mesoporous silica nanoparticles from chemical composition and morphology structure. The existing synthetic methods of dendritic mesoporous silica nanoparticles were introduced. The major factors of influencing the structure of dendritic mesoporous silica nanoparticles were mainly discussed. In addition, the future development on dendritic mesoporous silica nanoparticles was also prospected.

M'-type Nd³⁺:GdTaO₄ microcrystals, synthetized by a molten salt synthesis method, were investigated via temperature-/pressure-dependent photoluminescence measurement. In the test temperature range 293-373 K, the spectral positions of emissions from ³F_3/2→⁴I_9/2 transition exhibit high thermal stabilities. The temperature coefficient of ³F_3/2(R₂)→⁴I_9/2(Z₅) transition is only 0.003 9 cm^-1·K^-1. The intensity ratio between transitions of ³F_3/2(R₂)→⁴I_9/2(Z₂) and ³F_3/2(R₁)→⁴I_9/2(Z₂) has a large temperature dependence, and its relative sensitivity in the physiological temperature range is (0.60-0.52)(%·K^-1). In the test pressure range 10⁵ Pa-11.39 GPa, all the transitions linearly shift with pressure. The spectral position of ³F_3/2(R₂)→⁴I_9/2(Z₅) transition is very sensitive to pressure, with a sensitivity of 15.18 cm^-1·GPa^-1. The intensities and spectral widths of the transitions in the heating and compression processes were also analyzed. Compared with the other optical sensors in the near-infrared wavelength range, the good performance of M'-type Nd³⁺:GdTaO₄ in temperature and pressure sensing was revealed.

A series of Sr₂GdNbO₆:xEu³⁺ (x=0.04-0.12) red phosphors were prepared by a high-temperature solid-phase method, and the target products were characterized by X-ray diffraction, UV-Vis spectrophotometry and fluorescence spectroscopy. The results show that the synthesized phosphor has a monoclinic crystal structure with the space group P2₁/c. The structural analysis indicates that doped europium replaces Gd³⁺ ion in the matrix Sr₂GdNbO₆ with the chemical state of Eu³⁺ ion, thus forming a single crystal structure phosphor. Sr₂GdNbO₆:Eu³⁺ phosphor exhibits a red-orange emission under dual-wavelength excitation of blue light λ_ex of 468 nm and near-ultraviolet light λ_ex of 395 nm, and the main emission peaks are centered at wavelengths of 622 nm and 593 nm, which belong to the ⁵D₀→⁷F₂ and ⁵D₀→⁷F₁ energy level transitions of Eu³⁺, respectively. When the doping amount (x) of Eu³⁺ is 8%, its luminescence quantum efficiency for blue light excitation reaches the maximum value of 16%. Based on the analysis and comparison of the temperature (295-568 K) effect on the emission intensity and quantum efficiency under dual-wavelength excitation, the phosphor has a high luminescence quantum efficiency under the excitation of blue light λ_ex of 468 nm and a higher thermal stability. Under the excitation of blue light, the average fluorescence decay lifetime of the sample Sr₂GdNbO₆: 0.08Eu³⁺ is 0.841 ms, the color coordinates are (0.648, 0.368), and the luminescence purity reaches 93%. This phosphor is a kind of red fluorescent material with the dual-wavelength response for a promising potential application.

To address the technical challenge of the slow repair rate of microbial-based exo-remediation materials, microbial-sodium alginate exo-remediation materials were prepared by adding different concentrations (0.0%, 0.5%, 1.0%, 1.5% and 2.0%) of sodium alginate to the existing microbial exo-remediation material, and analyzed their properties and synergistic exo-remediation effect. The results show that the viscosity of the microbial-sodium alginate exo-remediation materials increases, while the flow rate decreases as sodium alginate concentration increases; the repair product formed by the microbial-sodium alginate external repair material is white in color and has a certain elasticity, and the composition of the repair product is mainly calcium carbonate, while the calcium alginate gel formed is filled in the gaps between calcium carbonate particles; and for different crack widths, the microbial calcium alginate hydrogel formed by microbial-sodium alginate external repair material can achieve instant plugging, resulting in a lower water penetration coefficient and a higher compressive strength. In particular, the optimum repair effect for 1.0 mm cracks can be achieved at a sodium alginate concentration of 0.5%, which reduces the water penetration coefficient from 9.76 to 0 under a maintained water pressure of 1 kPa, and achieves a strength recovery rate at 7 d of 22.7%.

The interface bonding quality is critical to the repair effect of repaired cementitious materials. In present, there is no proper method to accurately evaluate whether the interface can establish the effective mechanical connection. This work proposed a method to visualize the interface bonding effect of cementitious materials repaired zone. The volume images on three repaired mortars with different bonding areas during loading process were obtained via in-situ X-ray computed tomography. The digital volume correlation (DVC) was employed to analyze the volumetric strain distribution of samples based on the obtained images. As there is no constraining in de-bonding area, a greater deformation occurs in the loading process than in the bonded area. Therefore, the area without a mechanical bond in the repaired mortar can be visualized through the strain mutation in the DVC strain contour. The results show that the strain mutation area detected in the DVC results corresponds well with the artificial de-bonding area, indicating that this method can detect the de-bonding area in the repaired mortar.

To improve the mechanical properties of conventional sticky rice-lime mortar, high strength pregelatinized sticky rice-lime mortar (HPR-LM) was modified with a pregelatinized sticky rice via accelerated carbonation. The effects of mass fraction of pregelatinized sticky rice and water-solid ratio on the carbonation properties of HPR-LM were investigated. The results show that the maximum carbonation reaction degree of HPR-LM with sufficient water and larger porosity can be obtained at a water-solid ratio of 0.3. The change of conductivity and pH value of saturated Ca(OH)₂ solution slows down, and the temperature increase of HPR-LM reduces due to the action of pregelatinized sticky rice, thus retarding the carbonation of HPR-LM. CaCO₃ precipitation forms fusiform calcite on the template of molecular chain of pregelatinized sticky rice. The compressive strength of HPR-LM with 3% pregelatinized sticky rice is 56.8% higher than that of pure lime mortar, and calcite grain reaches the minimum size and the density of HPR-LM becomes the maximum value.

Alkali-activated binder is considered as one of green environmental low-carbon cementitious materials. However, this binder has not been produced commercially and used widely in civil engineering so far. Based on the analysis on the keynote reports on alkali-activated binder in International Conferences on Cement Chemistry, recent work on alkali-activated binder focus on its composition, microstructure of hardened paste and properties. There is a lack of work on building elements and structure made with this binder. This issue hinders the establishment of technical standard system of alkali-activated binder and related design norm of building structure. This could result in a great barrier of the commercial production of alkali-activated binder. As a result, it is rather difficult to enhance the application of alkali-activated binder.

Si₃N₄-SiC ceramics were prepared via reaction sintering with SiC, silicon powder and SiO₂ as main raw materials, and the ceramics were oxidized at a high temperature. The structure and properties of ceramics before and after high-temperature oxidation were investigated. The results show that the main crystalline phases of the samples before high-temperature oxidation are SiC, α-Si₃N₄/β-Si₃N₄ and a small amount of silicon powder, Si₂N₂O and triclinic-SiO₂, while the silicon powder disappears after high-temperature oxidation and forms tetragonal-SiO₂. The mass fraction of β-Si₃N₄ remains constant, and the mass fraction of α-Si₃N₄ decreases from 11.3% before high-temperature oxidation to 6.8% after high-temperature oxidation, while the mass fraction of Si₂N₂O and SiO₂ increases, indicating that α-Si₃N₄ can be decomposed into Si₂N₂O and SiO₂ more easily than β-Si₃N₄. After high-temperature oxidation, the flexural strength of samples decreases from (68.55±6.36) MPa to (49.80±4.96) MPa mainly due to the decomposition of α-Si₃N₄ into Si₂N₂O and SiO₂.

Until now, many studies have been carried out to investigate the effect of reinforcement corrosion on concrete cracking due to chloride attack, but they mainly focus on monolithic reinforced concrete structures, and few studies on the durability of new and old concrete structures. Eight integral casting and secondary casting concrete specimens with different water-cement ratios (i.e., 0.60 and 0.53) were fabricated, and the semi-immersion accelerated corrosion was examined. The development law of rust expansion cracks on the concrete surface and the changes in the mechanical properties of the rusted steel bars for the secondary-casting specimens were investigated and compared with the integral-casting specimens at different theoretical corrosion rates of steel bars of 4%, 6% and 8%, respectively. The results show that the integrally poured concrete specimens only produce longitudinal cracks along the reinforcement, while the secondary-casting concrete specimens firstly produce interfacial transverse cracks and then produces longitudinal cracks. The steel bar in the integral-casting specimen is uniformly corroded, while the steel bars in the secondary pouring specimens are non-uniformly corroded, and the steel corrosion at the interface between unused and used concrete occurs most serious. The mechanical properties of the steel bars are reduced in the secondary-pouring specimens compared to the integral-pouring specimens due to the serious loss of the steel bar section at the interface between unused and used concrete. The influence of concrete strength on the mechanical properties of steel bars in the integral-casting specimens can be ignored, but it has an influence on the mechanical properties of steel bars in the secondary-casting specimens.

The hydration activity of ternesite-dicalcium silicate composite minerals in deionized water, NaAlO₂, Li₂CO₃ and MgSO₄ was investigated. The results show that the presence of 1 mol/L [Al(OH)₄]^- ions in liquid significantly improves the hydration activity and accelerates the hydration of ternesite-dicalcium silicate composite minerals due to the formation of ettringite, and enhances the strength of ternesite. The strength of hydration products is 44% higher than that in deionized water. However, the presence of 0.1 mol/L Li⁺ ions in liquid inhibits the hydration, and the strength of hydration product is only 26% of that in deionized water. The presence of 1 mol/L Mg²⁺ ions in liquid improves the hydration activity of ternesite-dicalcium silicate composite minerals from 28 d to 56 d, but it inhibits the hydration activity after 56 d.