Latest ArticlesWhispering gallery mode (WGM) microcavity is an efficient laser resonator, which can trap light in a rather small space, achieve a high light energy density and greatly enhance a light-matter interaction. Among numerous materials, rare-earth (RE) element ions doped nanocrystals-in-glass composite (NGC) can be used as an ideal candidate for WGM microcavity lasers due to its superior optical properties of crystals and outstanding mechanical processing properties of glasses. However, a few works on WGM microcavity lasers based on RE-doped NGC are reported. In this review, the basic principle and characteristic parameters of WGM microcavity were briefly described, and recent development on the WGM microcavity lasers made of RE-doped NGC was summarized. In addition, the corresponding future development was also forecasted.
Glass is widely used in sealing and connection of various optoelectronic devices due to its favorable heat resistance, excellent electrical insulation, and adjustable expansion coefficient. This review briefly represented the interaction mechanism between sealing glass and substrate materials, such as glass, ceramics, metal, silicon wafer, etc.. Besides, recent development on sealing glass in new energy devices, photoelectronics and other applications, such as silicon solar cell electrode, organic light-emitting diode, solid oxide fuel cell, was described. In addition, the critical research and key issues of sealing glass were also discussed. The related applications and future development of sealing glass were summarized and prospected.
This review represented recent development on Li/Na chalcogenide glassy/glass-ceramic electrolytes, i.e., the interface stability, solid-solid interface contact and lithium penetration between the chalcogenide electrolytes and electrodes. In addition, the corresponding future development was also prospected.
Chalcogenide (ChG) fibers become the only nonlinear fibers for midwave- and longwave-infrared supercontinuum (SC) generation due to the high transmittance in infrared region and high nonlinearity. The results of work on mid-infrared SC in the last five years were reported. This review represented recent development on ChG fibers, including experimental SC generation of step-index, micro-structured & multi-clad chalcogenide fibers and all-fiberized SC sources.
Effect of temperature rising inhibitor (TRI) on the hydration process of cementitious materials containing fly ash and the performance of concrete was investigated. The hydration process of cementitious materials was examined as a function of the contents of fly ash and TRI. The adiabatic temperature rise, mechanical properties and drying shrinkage of concrete derived from the cementitious materials and TRI were also evaluated. According to the hydration heat of the binder pastes, it was revealed that the addition of TRI lowers and delays the exothermic peaks more significantly in the presence of fly ash. The phase composition and microstructure of the hardened paste indicate that TRI mainly inhibits the hydration degree of the cementitious materials in the first 7 days. The presence of TRI slows down the adiabatic temperature rising rate, reduces the early strength of the concrete and increases drying shrinkage of the concrete.
A self-healing agent that can bind aggressive seawater ions and accelerate the healing process was developed, which was encapsulated as artificial aggregates. The closure ratio of a 400-μm-wide crack is 80% after self-healing for 24 h in seawater by using the self-healing agent, which is 4 times greater than that in referenced specimens. The reaction products formed at the crack mouth are mainly brucite and calcite, while in the aggregates intersected by the crack there are portlandite, calcite, Friedel's salt, ettringite and hydrotalcite, indicating that the aggressive ions can be bound by the self-healing agent. The mineralogy and distribution characteristic of the reaction products are dependent on the diffusion of the ions dissolving from the agents and the thermodynamic equilibrium constants of the reaction products.
Macrocell corrosion occurs in concrete structures universally, which accelerates the deterioration of concrete structures, when combined with microcell corrosion. In recent years, the durability problem caused by macrocell corrosion becomes more prominent with the advancement of engineering construction in China, thus demanding the corresponding protection. Nevertheless, there are many factors influencing the corrosion of microcell and their causes are relatively complicated, thus becoming a great challenge in the field of corrosion science and technology. This review offered an overview on the progress and prospects of macrocell corrosion of steel bars in concrete, including theory of the mechanism and influencing factors. In addition, the future research direction of macrocell corrosion was also discussed.
The corrosion state of composite binder mortar with metakaolin (MK) in chloride environment was investigated by measuring corrosion potential, linear polarization and cyclic potentiodynamic polarization. The relationships among different electrochemical parameters were analyzed. In chloride environment, the corrosion potential of the reinforcing steel in the composite binder mortar increases, the corrosion rate decreases and the pitting corrosion resistance enhances with increasing the MK content as the MK content is < 30% (accounting for total mass of MK and cement). The corrosion current density and corrosion potential are correlated to composite binder mortar. The degree of pitting corrosion of the reinforcing steel in the composite binder mortar is well reflected by main electrochemical parameters of cyclic potentiodynamic polarization. The presence of MK modifies the pore structure and reduces the permeability coefficient of the chloride in the composite binder mortar. The depassivation time of the reinforcing steel and the expected cracking time of reinforcing steel cover both are prolonged when the composite binder mortar is added.
Sulfur oxidation characteristics of sulfur oxidizing bacteria under different substrates and the mechanical properties and microstructure of mortar samples were investigated. The growth concentrations of sulfur oxidizing bacteria are different under different substrates, i.e., the corresponding growth concentration decreases from high to low in an order of Na2S2O3, Na2SO3 and Na2S. The natural oxidation and biological oxidation both occur in the transformation of SO42- by the sulfur oxidizing bacteria under different substrates. S2O32- can be transformed to SO32- through SseA enzyme and then to SO42- through Soe enzyme. The swelling gypsum content of mortar sample under Na2S2O3 substrate is lower than that under Na2SO3 substrate. This is because SO42- concentration of natural oxidation of Na2SO3 is greater than that of the biological oxidation, thus leading to a higher reaction rate and a stronger corrosion effect. The compressive strength and mass change rate of the mortar samples under Na2S2O3 substrate are 10.4% and 1.04%, respectively. The change rate of compressive strength and mass of the mortar samples under Na2SO3 substrate are -12.9% and 1.44%, respectively. Combined with the mineral composition analysis results, it is indicated that the gypsum content of the samples under Na2S2O3 substrate is lower than that of the samples under Na2SO3 substrate, while the mortar samples are eventually deteriorated, due to the expansive force of a large amount of gypsum after 75 d and 45 d.
1H low-field nuclear magnetic resonance instrument was used to continuously monitor the changes in the transverse relaxation time of white cement with silica nanoparticles with different sizes (i.e., 15 nm, 50 nm and 100 nm) from adding water to hydration for 72 h. The effect of silica nanoparticles with different sizes on the hydration process of cement was investigated. The setting time of cement paste was measured using the Vicat apparatus. The results show that the crystal nucleation of silica nanoparticles can affect the early hydration process of cement, thus breaking the flocculation structure of cement paste due to the physical adsorption and pozzolanic reaction, reducing the number of macropores, and improving the uniformity of cement paste. In addition, the smaller the silica nano particles is, the less the free water content in hydration process and the shorter the setting time will be.
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