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The significant effect of desert sand on cement-based composites was observed in the previous investigation. However, how the composition of fine aggregate affects the formation of air void structure remains to be investigated. In this paper, mortars composed of five different sand mixtures were prepared, and the specific surface area (SSA) of the sand mixture with different content of fine aggregate was calculated. It was observed that the air void content decreased as the SSA value of the sand mixture increased. A negative-slope linear relation was observed between the SSA values and air void content in the composite construction sand fiber reinforced mortar system. With the increase of SSA, the air void number of every high-strength fiber reinforced mortar decreased from 12,446 to 6652. With the gradual increase of desert sand content, the count of air void number decreased. When the fine aggregate was completely desert sand, the air void content of the fiber-reinforced mortar dropped from 1.21% to 0.98%. Through the analysis of the 3D air void system, it can be concluded that the mixture of fine aggregate with different particle size distributions plays a positive role in optimizing the air void characteristics. Reasonable utilization of desert sand can significantly improve the pore structure characteristics and compressive strength of cement-based composites, which provides an effective theoretical basis for the development and utilization of desert sand resources. The function of different kinds of construction sand in the formation of air-void structure was investigated by X-CT technology. A negative-slope linear relationship was discovered between specific surface area (SSA) values and the entire air void content in the composite construction sand fiber reinforced mortar system. The mixture of river sand and desert sand plays a positive role in optimizing the air void characteristics and compressive strength. [ABSTRACT FROM AUTHOR]

High-efficiency warmth retention materials are urgently needed by human living in extremely cold environment to maintain their health and physical function. However, most existing fibrous warmth retention materials suffer from large weight, inefficient warm retention performance, and poor antibacterial ability. Here, we propose an innovative strategy to construct ultrafine fibrous sponges with interlaced crimped-fiber architecture by direct electrospinning technology. The stable three-dimensional (3D) network structures assemble from tangly curled ultrafine fibers, endowing the obtained sponges with ultralight characteristics (4.5 mg cm−3), robust elastic resilience (nearly full recovery from 100-cycle compressive deformations), and low thermal conductivity (24.1 mW m−1 K−1). Moreover, the in situ doping of chlorhexidine and fluoropolymer enables the sponges with efficient and durable antibacterial performance after washing processes (antibacterial rate up to 95.6% after 10 recycle washing experiments). This work opens a new way for the design of 3D fibrous materials with remarkable antibacterial performance for various fields. [ABSTRACT FROM AUTHOR]

Traffic noise does great harm to the physical and mental health of humans, which has become the main source of noise pollution, making sound absorption materials highly in demand. Fibrous sound-absorbing materials are widely used in controlling traffic noise pollution; nevertheless, due to the monotonic internal structure and large fiber diameter, they suffer poor mechanical properties and sound absorption performance. Herein, we develop a credible way to create flame-retardant fibrous sound absorption sponges by humidity-assisted electrospinning and an in-situ crosslinking approach. The obtained fibrous sponges possess outstanding superelastic and hydrophobic properties. Most importantly, fluffy fiber networks endow sponges with good low-frequency sound-absorbing properties (noise reduction coefficient or NRC of 0.51) and lightweight features (density of 9 mg cm−3) compared with commercial and reported sound-absorbing materials. This work will shed light on future research in developing excellent sound-absorbing materials. [ABSTRACT FROM AUTHOR]

AbstractThe study of emulsion stabilization mechanisms is of great importance in the field of crude oil extraction, transportation and processing. In order to further investigate the roles of asphaltenes and surfactants in the emulsion stabilization process, the adsorption mechanisms of asphaltenes and surfactants at the oil-water interface were investigated using dissipative particle dynamics. The results show that: the asphaltene interfacial film gradually becomes thicker before the saturation adsorption of asphaltene molecules at the oil-water interface, and the interfacial tension decreases with the increase of the number of molecules until it reaches the equilibrium state; different surfactant molecules have different influences on the interface, and the calculations of the radial distribution function and the interfacial tension show that H2T4 molecules have a stronger effect than H4T4 at the oil-water interface and have stronger surface activity. H2T4 reaches saturation adsorption capacity faster than H4T4 and has higher interfacial efficiency. The asphaltene-surfactant composite system can stabilize the oil-water interface more effectively. Competitive and synergistic effects of asphaltene and surfactant in the process of interfacial adsorption. When the concentration of surfactant in the composite system is low, there is a synergistic effect between the two in the interfacial adsorption process; when the concentration of surfactant is high, there is a competitive effect between the two in the synergistic adsorption process. The surfactant H4T4 has both interfacial adsorption and self-aggregation in the competitive adsorption process. This paper provides ideas for exploring the kinematic laws of molecular behavior in the stabilization mechanism of crude oil emulsions. [ABSTRACT FROM AUTHOR]