Abstract: By establishing a boron nitride-doped graphene system and using molecular dynamics simulation to measure and characterize its frictional behavior, it was found that the doping of boron nitride significantly affects the friction behavior of graphene. this study focuses on the outer layer of pinned atoms on the indenter that have a decisive influence on the friction performance and calculates the resistance of such atoms during the sliding process of the indenter. In addition to the van der Waals cohesive energy, the deformation of the 2D film near the pinned atoms is also studied. The results show that boron nitride doping not only reduces the friction resistance of graphene, but also changes the friction peak value from a basically constant state to a large amplitude and long-period oscillation. Here, changes in the frictional properties and behavior of the doped graphene can be attributed to higher cohesive energy between boron nitride and the indenter, lower adhesion/frictional resistance, and lower strain of the doped graphene around the pinned atoms. Read More

Abstract: Red mud is an industrial solid waste produced during alumina extraction from bauxite. This study aims to enhance red mud's reactivity and develop a composite cementitious material to increase its utilization rate. The methods used include individual red mud calcination and co-calcination with calcium carbide slag (RM-CS). The physical and chemical properties of red mud were assessed using X-ray diffraction (XRD) and thermogravimetric-differential scanning calorimetry (TG-DSC) analyses. Results show that dolomite (CaMg (CO3)2) in red mud starts to decompose at 500°C and is nearly fully decomposed by 900°C. The physical and chemical properties of the composite cementitious material were analyzed via XRD and compressive strength tests. The findings indicate that the 28-day compressive strength of the red mud composite material reaches 60 MPa, while the RM-CS composite material reaches 64 MPa. Toxicity leaching results indicate that the heavy metal ion content in the composite material complies with standard requirements, suggesting that the composite cementitious material is environmentally friendly. Read More

Abstract: In order to realize the resource utilization of fluoropygite, the gelling material was prepared by using fluoropygite, fly ash and calcium carbide slag as composite raw materials. The optimal ratio was optimized by single factor test and orthogonal test, and the hydration mechanism and curing effect of fluoride ion were studied. The results show that the optimal ratio of strength for 3 days is fly ash: fluoropyssum: calcium carbide slag = 50:30:20,7 days the optimal ratio of strength is fly ash: fluoropyssum: calcium carbide slag = 50:25:15,28 days the optimal ratio of strength is fly ash: fluoropyssum: calcium carbide slag =60:30:15. By XRD and SEM analysis, the addition of calcium carbide slag has a certain curing effect on fluorine ions in fluoropogon. Read More

Abstract: Pursuing low-carbon development in green mining requires improving the efficiency of solid waste utilization. This study developed a high-strength green cement-based composite grouting material using silicate cement and fly ash as the primary cementitious materials, with its toughness enhanced by the incorporation of nano-silica (NS). Various testing methods, including slurry property and mechanical strength tests, as well as advanced techniques such as XRD and SEM, were employed to comprehensively analyze the effects of NS dosage on hydration products, working properties, setting time, and mechanical strength. The results demonstrate that adding NS effectively reduces the initial setting time of the fly ash-cement composite slurry. Moreover, as the NS dosage increases, the fluidity, hydration rate, and compressive strength of the composite slurry initially increase and subsequently decrease. At an NS dosage of 1%, the composite slurry achieves optimal performance, with a 1% increase in fluidity, a 5.9% reduction in initial setting time, and compressive strength improvements of 12.6% and 37.8% at 3 and 90 days, respectively. Microscopic characterization indicates that the addition of an appropriate amount of NS significantly enhances the volcanic ash effect, consuming substantial amounts of Ca(OH)2 and generating abundant hydrated calcium silicate products. In addition, the unhydrated NS can also play a filling effect, significantly improving the matrix's densification. These findings provide new insights into the development of cost-effective, high-performance green grouting materials for deep coal mine engineering, offering both theoretical and practical significance. Read More

Abstract: The emerging cellulose acetate film is also a composite material with excellent cooling properties due to its excellent flexibility and good film-forming properties, and nowadays it has become a key material used for radiation cooling. Since the cross-section of the columnar skeleton of cellulose acetate film is irregular and heterogeneous, which is not the traditional circular shape, at present, domestic and foreign research mainly analyses the circular shape, and does not explore the influence of the heterogeneous shape on the scattering effect of cellulose acetate film in depth. Therefore, in this paper, through the Mie scattering formula, the complex refractive index of cellulose acetate film in actual measurement is substituted into the formula for the simulation of scattering efficiency, extinction efficiency, absorption efficiency and backward scattering efficiency factor of the particles, and on the basis of this, different size parameters of the particles are simulated to obtain the relationship between the scattering direction of the particles and the size parameters. After that, the heteromorphic shape was modelled and simulated based on the Fourier formula in polar coordinates, which was substituted into the simulation software for comparing the light scattering cross section of the heteromorphic shape with that of the traditional circular shape, and then the heteromorphic shape was adjusted and optimized on the basis of the same cellulose acetate film. It is found that the heteromorphic shape has a larger surface area than a circle, and its special shape can form an asymmetric radiation route, which can scatter the light emitted from the side better, thus providing a feasible graphical solution for the preparation of cellulose acetate radiation-cooled films. Read More

Abstract: Decreasing the surface friction coefficient of medical catheters is important especially in interventional treatment, but the current solution involves high cost or cumbersome manufacturing processes. In order to effectively solve the problem of high friction coefficient of the inner and outer layers in the use of medical catheters and simplify the manufacturing process, we use polytetrafluoroethylene (PTFE) as a catheter material to graft directly with PAAm hydrogel. In order to overcome the high chemical inertness and low surface energy of PTFE, nitrogen ion injection is used to modify the surface of PTFE. The resulting porous PTFE surface is loaded with initiators and the hydrogel monomers polymerize in situ to form a lubricating layer. The hydrogel coating is strongly bonding on PTFE substrate, the maximum 180° peel strength between PAAm hydrogel and PTFE substrate reaches at 222 N/m. The hydrogel lubricating layer provide a friction coefficient of 0.04. In addition, in comparison to silicone rubber, the surface biofilm adhesion is diminished by 350%, demonstrating exceptional anti-fouling characteristics. This study provides a new idea and method for the surface low friction design of implantable medical devices. Read More

Abstract: In order to study the influence of environmental temperature and humidity changes on the creep effect of large-span concrete cable-stayed bridges, taking the Mysterious Valley Lancang River Bridge as the background, combined with the measured data of environmental temperature and humidity at the bridge site, and based on the standard model, a creep correction model considering the time-varying of temperature and humidity was established, and compared with the standard model with constant temperature and humidity. The research results indicate that after considering the time-varying effects of temperature and humidity, the displacement and internal forces of the main beam, the displacement and internal forces of the bridge tower, and the cable forces of the inclined cables caused by creep effects will continue to increase. Neglecting the changes in environmental temperature and humidity will underestimate the impact of creep effects. Adopting a modified model that considers the time-varying effects of temperature and humidity can improve the prediction accuracy of long-term creep effects in large-span concrete cable-stayed bridges, which is beneficial for bridge design, construction process monitoring, and later operation and maintenance. Read More

Abstract: In the field of plastic color matching, the accuracy of color prediction directly affects the precise control of attributes such as hue, brightness, and saturation, thereby influencing the coloring effect of pigments. This paper conducts an in-depth study based on many-flux method and finite difference analysis, dividing the scattering medium into multiple light transmission channels according to the angle of light incidence. We investigate the flux transfer relationships between the channels to address the shortcomings of the Kubelka-Munk(K-M) theory in achieving satisfactory coloring effects in non-diffuse environments with weak scattering or thin media. Using polypropylene as the substrate, we analyze the optical properties of pigments under D65 light sources with a 10nm interval. Under conditions of higher transparency and lower scattering coefficients, we establish the relationship between the absorption coefficient K, scattering coefficient S, and reflectance R. Finally, we compare the experimental results with the reflectance errors of actual samples to optimize the theoretical model, thereby improving the coloring performance, by analyzing the K-M theory model and the multichannel model for high-concentration red pigment (DPP P.R.254) and high-concentration green pigment (Copper Phthalocyanine P.G.7). Read More