In order to explore the antimicrobic materials, new strategies for synthesis of particles were paid more and more attention as it was crucial to the advancement of material technology and environmental. In this work, we provided a strategy for construction of novel hollow-carved microspheres (HCMs) by a simple method of emulsion interfacial polymerization (EIP). Firstly, using sodium p-styrene sulfonate (SSS) and styrene (St) as hydrophilic/hydrophobic and rigid comonomers, diallyl dimethylammonium chloride (DMA) as cationic cross-linking monomer, azobisisobutyronitrile (AIBN) as initiator, hexane as a pore-forming agent, the HCMs were synthesized by EIP. Then, the quaternized HCMs (QHCMs) was prepared by quaternization of hydrophilic sodium sulfonate groups ( SO 3 Na). The composition and micromorphology of the obtained microspheres were characterized by FT-IR, XPS, EDS, DLS, SEM, and TEM. The antibacterial properties of QHCMs were tested against Escherichia coli and Staphylococcus aureus. At a concentration of 320 μg/ml QHCMs, the bacteriostatic activities of S. aureus and E. coli decreased by more than 91.7% and 86.4%, respectively, which was confirmed by the colony forming units and regeneration curves. In summary, a novel antibacterial polymer material was successfully synthesized by EIP and quaternization, which could be widely used in coating materials to reduce bacterial infection.
Large-scale inverted siphon is a key hydraulic structure for building a national water network and realizing the spatial balance of water resources, and its safety under the action of earthquakes has become the focus of trans-basin water transfer projects. In this paper, Xiazhuang inverted siphon of water diversion in Central Yunnan is taken as the research object. Viscoelastic artificial boundary was used to simulate seismic waves spread in the soil, which include the natural site seismic waves and the waves fitted manually according to the site conditions. A three-dimensional finite element model of soil-structure-fluid interaction was established by software of ABAQUS, in which the fluid-structure interaction was simulated by user-defined element (UEL) built on additional Mass Method. Seismic response and damage analysis of large inverted siphon structure are carried out by the model. The results show that the dynamic displacement of the inverted siphon pipe is mainly horizontal sloshing, and the dynamic response of the pipe increases due to the water in the pipe; even the dynamic stress value in some areas is close to the design value of the concrete tensile strength. The damage analysis of inverted siphon pipe shows that the plastic deformation and the damage area develop rapidly with the increase of the peak ground acceleration (PGA), and the tensile damage area is generally larger than the compression damage area. The damage factor of the pipe under the working condition of the water is obviously larger relative to the working condition of no water. Therefore, it is suggested that the damage effect of earthquake should be considered in the design of large inverted siphon in high-intensity area.
The creep behavior of rock has received much attention for analyzing the long-term response and stability of underground rock engineering structures. Numerous studies have been carried out on the creep properties of various rocks under pure compression conditions. However, little attention has been paid to the creep behavior of rocks in a combined compression-shear loading state. In this work, a novel combined compression and shear test (C-CAST) system was used to carry out inclined uniaxial compression tests and creep tests for various inclination angles (0°, 5°, 10°, and 15°). The results revealed that the peak strength of the coal decreased with the inclination angle of the specimen, which could provide the basis for setting up a creep test scheme. Multistage compression-shear creep tests were carried out on specimens with different inclination angles. Based on the analysis of the creep test data, the creep behavior of the coal in a combined compression-shear state was studied. It was found that the specimen inclination affected the time-dependent deformation, long-term strength (LTS), and time to failure. Compared with the specimen under pure compression, the inclination specimens tend to produce large shear strain with time, while they were more prone to shear failure. The reduction of the long-term strength was closely associated with the increase of the specimen inclination angle when the angle was more than 5°. Moreover, the ratio of the peak strength to the LTS was not affected by the specimen inclination, which is considered an inherent characteristic. We anticipate that the results obtained will assist in pillar design and long-term stability analysis.
Being the critical hydraulic structure in the construction of national water diversion projects, the large-scale aqueduct is one of the indispensable buildings in the rational allocation of water resources. Moreover, its safe operation during an earthquake is related to the success of the national water network’s construction. In this paper, HDRBs (high damping rubber bearings) have been used as the seismic isolation device for the large aqueduct, considering the FSI (fluid solid interaction) between the water and the walls of the aqueduct, and the mechanical model of HDRBs has been constructed by the bilinear model. The dynamic responses of the large aqueduct under different ground motion excitations, including different peak ground accelerations (PGAs) and operating conditions, have been calculated using the precise integration method. At the same time, the influence of RB (rubber bearings) and HDRBs, two kinds of bearings, on the seismic response of the large aqueduct is compared and analyzed. The maximum reduction in natural frequency with HRDB is about 72%, compared with the use of RB under different working conditions. When there is substitution of HDRB for RB, the stresses in the concrete at the corresponding positions decrease from 1.87 MPa to about 0.71 MPa. The analysis shows that HDRBs are equipped with well seismic isolation and energy dissipation performance, which can effectively reduce the seismic responses and improve the seismic performance of the large aqueduct. In addition, it shows that HDRBs have well adaptability to different operating conditions, ground motion excitation, and PGA, which can be extended to the constructions of aqueduct projects with high seismic intensity and complex geological conditions.
The cotton fabrics (CF) with durable and stable antibacterial function is very important in the field of medicine and public health, and it is still a challenge to explore highly efficient antibacterial materials. Herein, by using one‐pot method of soap‐free emulsion polymerization, a kind of polymer cationic broccolo‐shaped nanoparticles (PCBsNPs) with antibacterial activities was synthesized, and applied to coating CF, which afforded PCBsNPs coating CF (PCBsNPs@CF). It was characterized by Fourier transform infrared microspectroscopy, scanning electron microscopy, dynamic light scattering, X‐ray photoelectron spectroscopy and contact angle test. Their antibacterial efficiency against gram‐positive and gram‐negative bacteria was studied. It indicated PCBsNPs@CF presented efficient and long‐lasting antibacterial activities, and could effectively restrain bacterial adhesion. Its antibacterial and bacterial anti‐ adhesion mechanism was illustrated. Hence, PCBsNPs@CF had great application potential as clothing, medical dressings and home textiles.
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