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Reservoir operation strategies with low cost and high efficiency have been proposed to control algal blooms. However, the key hydrodynamic principle for performing reservoir operation strategies is still unknown, posing an obstacle to practical applications. To address this challenge, we proposed short-term emergency reservoir operation strategies (EROSs), established a three-dimensional (3D) eutrophication model of the Zipingpu Reservoir, and designed six 14-day reservoir operation cases to explore the mechanism of EROSs in controlling algal blooms. Large outflows with rapid water exchange should be adopted early in EROSs to control algal blooms in the reservoir. Small variations in the surface water temperature or the mixed layer depth/euphotic layer depth (Z

River ice in the upper Yarlung Zangbo River is characterized by seasonal freezing-thawing cycles (SFTC). It is important to explore the effects of SFTC on phosphorus release and transformation from upstream surface sediments to protect the ecosystem of the Yarlung Zangbo River. The process and mechanism of phosphorus release and transformation in sediments following SFTC were investigated in a laboratory simulation experiment. The results showed that after freezing, sediment particles were broken, the specific surface area was increased by 14%, and the particle size was decreased by 43%, which resulted in weakened adsorption of phosphorus by sediments. Moreover, the destruction of organic matter (OM) on the sediment surface will release more ion adsorption sites and promote the release of phosphorus. The bioavailabilities of exchangeable phosphorus (Ex-P), aluminum phosphorus (Al-P) and iron phosphorus (Fe-P) increased by 60.09%, 86.86% and 31.86%, respectively, after freezing. Organic phosphorus (O-P) is used indirectly by organisms, and O-P content showed a significant correlation with OM content. Water affected the oxygen content in sediments during the freezing period, and continuous hypoxia promoted the release and transformation of Fe-P and Al-P.

Effects of different retarders (gypsum, sodium citrate, sodium gluconate and borax) on setting and hardening behaviors of dehydrated cement paste (DCP) composite reactivated cementitious materials (DCRCM) are studied through determinations of setting time and mechanical properties. Mechanism of Early hydration and hardening is also studied based on hydration kinetics and SEM analysis. The results indicate that sodium citrate and gypsum are of poor retarding effect on DCRCM. Proper amount of borax will effectively retard the setting process. Sodium gluconate is of best retarding effect, whereas it will result in low early strength of DCRCM. When used as a retarder, borax is of obvious retarding effect. It can not only effectively restrain initial hydration process of DCRCM, but also accelerate early hardening process of DCRCM, promoting the establishment and development of mechanics strength. When the mixing amount of borax is 2%, both early and late strengths of DCRCM can reach to the maximum. SEM analysis shows that the hardening paste of DCRCM with borax is characterized by dense microstructure and less defects, greatly improving the mechanical properties of DCRCM.

The influence of borax on the early hydration and rheological properties of dehydrated cement paste (DCP) composite reactivated cementitious materials (DCRCM) is investigated through analysis of the hydration kinetics and measurement of rheological parameters. Results show that the presence of borax can effectively restrain the early hydration rate of DCRCM, and this leads to reductions in both the hydration products and the flocculent structure in the paste. Obvious shear thinning occurs in the fresh DCRCM paste with the increase of shear rate, followed by gradually stabilised viscosity. As the amount of borax is increased, the yield stress and plastic viscosity of DCRCM paste decrease and the rheological properties are significantly improved. However, when the amount of borax is 4%, the rheological type of DCRCM paste changes to shear thickening at a high shear rate, which is unfavourable in terms of the improvement of rheological properties.

This study explored the strength limitations of municipal solid waste incineration (MSWI) bottom ash-based geopolymer, which can limit its use in building materials. The calcium content in MSWI bottom ash was increased by the addition of varying amounts of granulated blast furnace slag (GBFS) and calcium-containing chemicals. The results showed that the low calcium content of MSWI bottom ash in geopolymer was the main cause of insufficient polymerisation. Both GBFS and calcium-containing chemicals improved geopolymer microstructure and enhanced the degree of polymerisation, which clearly improved the compressive strength. However, further increases in geopolymer compressive strength were not significant when the GBFS content was greater than 40%, and the compressive strength decreased sharply when hydrated Ca(OH)2 content was greater than 5%.

This study investigated the effect of activated silica on both the polymerization mechanism and strength development of municipal solid waste incineration (MSWI) bottom ash alkali-activated mortars, with a specific focus on increasing the silica content by adding either solid or liquid sodium silicate. The results show that such additives increase the content of active silicon and improve the resulting compressive strength of mortars, which is more effectively enhanced by liquid solid sodium silicate addition. However, a significant decline of these effects was found with increased addition of sodium silicate. Solid sodium silicate is difficult to dissolve; therefore, increasing its content not only fails to improve the content of active silicon but also causes precipitation. Using liquid sodium silicate could further improve the content of active silicon; however, excessive addition will result in a large surplus of activated silicon and thus, causing sodium and magadiite precipitation.

This study investigated the influence of different curing methods on the strength development of municipal solid waste incinerator bottom ash alkali-activated mortars. The results showed that standard room curing is not suitable for alkali-activated materials. The main reason for this is the humidity > 95% in the curing room, which causes wet sample surfaces. This leads to OH− and free alkali leaching, which severely affects strength development. Soaking curing further aggravates this effect. However, seal curing effectively prevents the leaching of OH− and free alkali and thus maintains high alkalinity, which benefits the strength development. Therefore, the method of seal curing is more suitable for alkali-activated materials.

This study investigated the carbonation resistance of municipal solid waste incinerator (MSWI) bottom ash alkali-activated concrete (BA) and Portland cement concrete (CC) through the accelerated carbonation test. The results show that BA has lower resistance against carbonation compared to CC under the conditions of the accelerated carbonation experiment. However, BA displayed a unique anti-diffusion behavior under natural conditions which significantly reinforced its carbonation resistance. The anti-diffusion behavior was closely related to the amount of liquid sodium silicate in the activator. Moreover, the pH value in complete carbonation zone of BA was much higher compared to that of CC. The main reason is that liquid sodium silicate turned into magadiite in BA and then the magadiite turned back to liquid sodium silicate to release a large amount of OH− under low concentrations of CO2. This resulted in a rapid increase in pH value of the pore fluid and generation of the anti-diffusion behavior.

When ordinary Portland cementitious concrete is subjected to elevated temperatures, lots of pores and cracks are produced in the cement matrix. In order to solve the problem of pore and crack repairing, a phase change material (PCM) with a melting temperature of 450 °C was prepared in the laboratory. Ordinary Portland cement with addition of the PCM is termed as phase change cementitious material (PCCM). High temperature resistance of PCCM was investigated according to changes in surface morphology, mechanical strength and mass, as well as micro and meso structures of the PCCM matrix at high temperatures of 500 °C,600 °C,700 °C,800 °C and 900 °C. The results show that the compressive strength of PCCM mortar specimens is increased with temperature lower than 600 °C compared with that at room temperature, and that compressive strength loss of PCCM mortar specimens after exposed to 900 °C can be reduced to 48.5%. The PCM in PCCM matrix experience phase changes from solid to liquid phase at elevated temperatures. The melted PCM is able to fill pores and cracks in PCCM matrix. Once the temperature decreases to room temperature, the melted PCM becomes in solid phase again. Pores and cracks in PCCM matrix are thus repaired, resulting in improved microstructure of PCCM compared with that of ordinary Portland cement. Therefore, high temperature resistance of PCCM is much better than that of ordinary Portland cement.

The disposal of cement-based construction waste and the reduction in cement consumption are two bottlenecks for the cement and concrete industry. However, these two issues can be tackled simultaneously through reactivating hydrated cement paste (HCP) to be used as new cementitious materials. Moreover, the reactivated HCP can be used together with other solids waste, such as coal gangue (CG), to improve the grinding effect and reactivity. This study aims to investigate the co-utilization of HCP and CG with special focus on its flowability, mechanical properties, phase composition and hydration mechanism. It has been found that the addition of CG could increase the grinding time before agglomeration happened (from 6 min at 0% CG to 15 min at 15% CG and 35 min at 30% CG). Therefore, the final grain size of solid particles was decreased after CG addition. Partial replacement of ordinary Portland cement with HCP and CG could lead to a decrease in the flowability (between 2.3% and 7.1% depending on the HCP to CG proportion). The flowability was further decreased after the calcination. The strength of the mortar was also decreased after HCP + CG replacement (between 21.6% and 36.6%). However, the calcination activation promoted strength development. XRD and FT-IR results indicate the HCP calcination led to the generation of lime and β-C2S, the content of which had a positive correlation with the calcination temperature. The addition of CG resulted in a decrease of the lime content and the generation of new mineralogical phases, including quartz and mayenite.

To clarify the corrosion mechanism of steel induced by transverse crack, a study on the influence of crack widths and epoxy coating on corrosion of steel bars in cracked concrete is presented here. Microcell and macrocell corrosions of bars were investigated on single crack specimens with crack widths of 0.08, 0.26, 0.38 and 0.94 mm. The entire study was carried out in an artificially created chloride ion-induced corrosion environment. The results show that the steel in cracks was activated once the transverse crack occurred on concrete element, and the macrocell corrosion must co-exist with microcell corrosion of reinforcements in test specimens with transverse crack. The macrocell current of steel elements were separated from the crack width, and the wider the transverse crack is, the higher corroded area and the greater microcell current of the rebar is. Oxygen and water go into concrete through crack instead of through concrete cover. The epoxy coating cannot prevent the occurrence and propagation of crack, so it was not effective to prevent corrosion of steel bars in cracked concrete.

Phosphorus is an important limiting biogenic material. The special topography and climate of the Yarlung Zangbo River Basin generate unique distribution and transport characteristics of total phosphorus (TP). A survey of TP concentration, precipitation, runoff, sediment content, suspended load discharge, and relevant data was carried out for the Yarlung Zangbo River Basin in the last ten years. In combination with the regional geography and social economies, the basic spatial-temporal characteristics of P-water-sediment were analyzed by using the correlation and time series analysis methods. Furthermore, the transport characteristics of P and the main control factors were also studied. The results show that the TP concentration in this basin displays the characteristics of interannual cyclical variation and annual phasic variation, and the peak value appears in the wet season. Among the Yarlung Zangbo River, Nyangqu River, Lhasa River, and Nyang River, the TP concentration is the highest in the Nyangqu River, exceeding 0.4 mg/L several times in the wet season. In this basin, the distribution patterns of the TP concentration are similar to those of the rainfall, runoff, suspended load discharge, and sediment concentration. The coupling property of the TP concentration is the strongest with the suspended load discharge among the meteorological and hydrological parameters. The spatial variation of dissolved P in the wet and dry seasons in 2016 responded to the distribution patterns of the population density, environmental factors, farming, and animal husbandry. This indicates that the TP in the water is mainly from non-point sources and is affected by agricultural, geographical, and ecological factors. The transport of TP is mainly controlled by the suspended load discharge due to precipitation.

This study investigates the resistance of an uncoated magnesium phosphate cement (MPC) protective layer to sulfate attacks through changes in its compressive strength and appearance. X-ray Diffraction (XRD) and scanning electron microscopy (SEM) microanalyses are conducted on the MPC layer concrete both before and after etching, where changes in the microstructure of the magnesium phosphate protective layer are analyzed during the corrosion process. In addition, this study also explores the intrinsic mechanisms of the MPC protective layer in terms of the resistance of concrete to sulfate. The results showed that the erosion resistance of the concrete to sulfate can be dramatically improved by the MPC protective layer. The structure and composition of the MPC protective layer are different in the sulfate erosion environment compared with those exposed to other environments: the protective layer is more closely bonded to the concrete and has a more compact structure. Therefore, the MPC protective layer is verified to have a significant protective effect on concrete against sulfate corrosion.

Astrocytes play a pivotal role in neuronal survival in the setting of post-ischemic brain inflammation, but the astrocyte-derived mediators of ischemic brain injury remain to be defined. 2-(2-Benzofu-ranyl)-2-imidazoline (2-BFI) is a newly discovered ligand for high-affinity imidazoline I2 receptors (I2Rs) mainly located on the mitochondrial outer membrane in astrocytes. We previously reported that in a rat model of cerebral ischemia-reperfusion injury, 2-BFI limits infarct volume, reduces neurological impairment scores, and inhibits neuronal apoptosis in the ischemic penumbra. This study was performed to clarify the underlying mechanism in an astrocyte oxygen-glucose deprivation (OGD) model. The results show that 2-BFI reduces lipid peroxidation and inhibits mitochondria apoptotic pathways.

Aiming at the achievement of sustainable development of drinking water source areas in Tibet, the key elements of the ecological compensation for drinking water source areas are discussed by means of theoretical analysis, investigation and model calculation, which include the subject and object, the standards, the patterns and the capital sources. And corresponding ecological compensation mechanism accord with the actual situation of Tibet urban drinking water sources areas is established. This study, which specially pays more attention to how to promote the marketization and the diversification of compensation channels, provides new perspective and scientific reference for the construction and management of drinking water source areas in Tibet.

As the largest wetland with the highest elevation located in urban region, the Lhasa Lhalu wetland is chosen as a typical area in this research. The wetland is regarded as “The Lung of Lhasa City” due to its outstanding ecological benefits. It will become more efficient and reasonable for the protection of wetland eco-environment by applying the principle and method of ecohydrology to set a series of ecological restoration thresholds of the Lhalu wetland. After analysis on ecohydrological changing process and characteristics of the Lhalu wetland in recent twenty years, a new coupled model is developed on the basis of groundwater flow model, soil water movement model, water sucking model of plant roots and plant evapotranspiration model. This coupled model can be applied to describe the eco-hydrological process of the Lhalu wetland and focuses on how plant biomasses react to various ground water levels and annual precipitation levels, based on which, we bring forward the restoration threshold value which provides scientific strategic base for ecological construction and management of the Lhalu wetland.