The development of prefabricated buildings increases the demand for using early strong agents in the production of prefabrication. As a new type of crystal early strength agent, synthetic calcium silicate hydrate (C-S-H) can significantly enhance the early strength of cement-based materials, but its poor dispersibility limits its application. In this paper, the polycarboxylate superplasticizers (PCE) with different side chain density were used as a dispersant to synthesis a series of C-S-H/PCE by means of co-precipitation method. The influence of C-S-H/PCE on the structure of C-S-H was studied with XRD, FT-IR, DLC. Moreover, its influence on the cement hydration behavior, hardened body strength and composition structure was investigated. The results show that the smaller the side chain density of PCE, the better the dispersion of C-S-H seeds and the smaller the particle size; the median particle size can reach 339.5 nm; the increase of the number of seed particles can provide more nucleation sites. The incorporation of C-S-H/PCE can significantly accelerate cement hydration, advance the exothermic peak of hydration acceleration by 1.3 h, and increase the heat release by 10.8% at 8 h. After the incorporation of C-S-H/PCE, the porosity of the hardenite of the cement slurry decreases at 8 h and 1 d and the compressive strength increases by 13% and 15%, respectively.

Suitable scaffold material is one of the keys to the successful construction of small caliber tissue engineering blood vessels in vitro. Fibrin gel with natural protein composition is an ideal source of scaffold materials. In this study, fibrinogen was used as raw material and mixed with a certain proportion of thrombin and calcium chloride, and the gel material was obtained through technical steps such as temperature control. Then, the clotting time, water absorption, degradation time and mechanical properties were tested. The microstructure of the material was observed by scanning electron microscope. Secondly, the hydrogel tubular scaffold was made by using a specific tubular mold. By loading human fibroblasts in the scaffold, the effect of fibrin gel scaffold on the growth of human fibroblasts was studied and its cytocompatibility was judged. The results show that the overall appearance of the fibrin gel obtained by this method is milky white, smooth and uniform in thickness; the average gel forming time is (172.0±4.7) s; the water absorption rate is 34.50%±1.87%; the complete degradation time is 7 days and the Young's modulus is (2624±295) Pa; the overall structure of the gel has certain stability; the microstructure of the gel is presented as porous mesh fibers, and the fiber diameter is (0.41±0.03) μm with average pore size of reticular fiber of (47.87±9.60) μm². After embedding human fibroblasts, the cells are morphologically intact and evenly distributed in the gel, and the cells survived well. This study provides a reference for the further study of in vitro construction of small caliber tissue engineering vascular graft.

As a kind of bionic material, honeycomb structure has remarkable advantages in many fields, such as impact energy absorption, lightweight and so on. Among them, the plateau stress and energy absorption of double-arrow honeycomb (DAH) are higher than that of hexagonal honeycomb under compression load. In order to further improve the specific energy absorption (SEA) of DAH, this paper proposed a circular double-arrow honeycomb (CDAH) by introducing double arc edges to replace the original straight edges of DAH, and the CDAH samples were prepared by 3D printing and quasi-static compression tests were carried. At the same time, the numerical simulation model of CDAH was established based on finite element software, and the accuracy of the model was verified by comparing with the experimental results. The critical impact velocity of CDAH was derived by using the impact wave theory, and the dynamic response of CDAH under different impact velocities in the plane was studied with the verified numerical model. The experimental and simulation results show that, as compared with DAH, both the plateau stress and the energy absorption of CDAH are higher. When the strain reaches 0.6, the SEA of CDAH is 71% higher than that of DAH. And there are obvious inverted “V” and inverted “U” shaped deformation bands under medium and high speed impact, showing good characteristics of negative Poisson's ratio. With the increase of impact speed, the plateau stress and specific energy absorption of CDAH are significantly increased, and the plateau stress under 100 m/s impact is 3 times higher than that under 5 m/s impact, which is helpful to the application in high speed impact protection.

Peptides, such as soybean peptide (SPE), play an important part in drugs targeted therapy and diagnosis. However, their intolerance for the extremely low pH and ionic barriers of the stomach makes them hard to be delivered orally. Transdermal delivery system can deliver drugs to the blood avoiding the obstacles of the gastric. In this paper, carboxymethyl cellulose/cationic starch/Ca²⁺ (CMC/CS/Ca²⁺) composite hydrogel was successfully prepared by freeze-thaw cycle, and it can overcome the barrier of penetration of water-soluble SPE in the stratum corneum during transdermal delivery. The results of particle charge detector (PCD), Fourier transform infrared spectroscopy (FT-IR) and rheology show that chemical and physical cross-linking occurs among CMC, CS and Ca²⁺, forming a stable hydrogel. Moreover, the interaction among SPE, CS and Ca²⁺ makes its mechanical properties meet the requirements of transdermal delivery. The results of scanning electron microscope (SEM) and specific surface area measurement (BET) illustrate that there is a porous 3D network structure in those composite hydrogels. The moisture content of the composite hydrogel is higher than 95.63% and remains above 97.34% after 25 min at 25 ℃. All composite hydrogels swell rapidly within 120 min, and the equilibrium swelling fraction can reach up to 636.23% at 720 min. Moreover, it is also indicated that the composite hydrogels have high affinity for water, which is the fundamental reason for improving the transdermal delivery efficiency of SPE. The results of in vitro release show that the release type of SPE releasing from hydrogel belongs to swelling controlled release type, and the maximum scavenging rates of DPPH radical and ABTS radical are 47.07% and 72.16%, respectively. The cumulative permeation per unit area of SPE is 0.55, 0.70 and 0.60 mg/cm², separately, and the cumulative penetration percentage is 84.13%, 92.93% and 92.57%, respectively. The appearance and pH value, thermostability and cold endurance of the hydrogel all meet the standards of QB/T 2872—2017. Therefore, these composite hydrogels are expected to be applied not only in transdermal delivery of peptides and protein drugs, but also in skin antioxidant care.

Modified asphalt sealant has excellent repair effect and low production cost, and has been widely used in crack repair, but there are still problems such as insufficient adhesion, low flexibility and low durability. Thermoplastic vulcanized silicone (TPSiV) has the advantages of silicone rubber such as stable structure, good weather resistance, high strength and high elasticity of thermoplastic polyurethane, showing excellent adhesion, durability, flexibility and high and low-temperature stability. In this study, 90# matrix asphalt was used as the main raw material. Firstly, furfural extraction oil (FEO) was used to pre-swelling TPSiV, and then high-speed shear method was used to prepare a series of high efficiency composite modified asphalt sealant by adding styrene-butadiene-styrene (SBS), waste rubber powder (CR), CaCO₃ and other modifiers. The effects of SBS, TPSiV, CR content and CR particle size on the properties of modified asphalt sealant were systematically studied. Finally, the formula was verified through the indicators of the whole set of sealant. The thermal storage stability of the sealant was characterized by softening point difference method. The microstructure of TPSiV and TPSiV modified asphalt was observed by fluorescence microscope and scanning electron microscope. The IR spectra of asphalt before and after modification were characterized by Fourier infrared spectroscopy (FTIR).The results show that the increase of SBS content significantly improves its high temperature performance, and the best dosage is 3%. TPSiV improves the flexibility and cohesiveness of sealant, and the best dosage is 3%. With the decrease of CR particle size, the high-temperature performance is improved, while the low-temperature performance is decreased. The optimal particle size is 40 mesh. With the increase of CR content, the high-temperature performance of modified asphalt is improved, and the best dosage is 22%. The best sealant formula SBS∶TPSiV∶CR∶CaCO₃∶FEO mass ratio is 5∶3∶22∶5∶3, which meets the requirements of storage stability. TPSiV has a rough surface structure and the surface attached with silicone rubber particles is conducive to its adhesion to asphalt, and TPSiV disperses evenly in the composite modified asphalt. Chemical modification and physical modification of TPSiV compound modified asphalt exist simultaneously.

Synthesis of high refractive index nanocomposite by solution blending method can control the particle size distribution and surface properties of nanoparticles, and improve the dispersion of nanoparticles in organic matrices. TiO₂ nanoparticles are widely used in areas such as optical devices, sensors and photocatalysis because of their excellent photoelectric performance. The homogeneous dispersion of TiO₂ nanoparticles in the organic solvent is an important prerequisite for preparing high refractive index nanocomposites by solution blending method. In this paper, three kinds of silane coupling agents (SCAs) with different carbon functionalities were used to modify the surface of TiO₂ nanoparticles, which can be dispersed in three organic solvents with different polarities to obtain a transparent and stable dispersion. Results indicate that the median particle size (D₅₀) of TiO₂ nanoparticles in heptane, butyl acetate and 1-butanol are 13.5, 19.6 and 22.1 nm, respectively, and the distribution coefficients (PDI) are 0.038, 0.231 and 0.171, respectively. Dynamic laser scattering (DLS) measurements and transmission electron microscopical (TEM) observation indicate that the TiO₂ nanoparticles are dispersed on a primary particle size level. Turbiscan stability analyzer analysis demonstrates that TiO₂ dispersions with the same mass fraction of TiO₂ nanoparticles have different dispersion stability, indicating that the best compatibility is hexadecyltrimethoxysilane and heptane, and the dispersion has high dispersibility and good stability, followed by 3-(methacryloyloxy)propyltrimethylsilane with butyl acetate. This study indicates that the properties of the carbon functionalities of the SCAs are vital to the dispersion state of TiO₂ nanoparticles in organic solvents, and provides a new idea for the preparation of dispersion with high dispersibility and stability.

In order to solve the shortcomings of low hardness and poor wear resistance of TC4 titanium alloy, this study prepared titanium-based hard coatings reinforced by HfC, TaC and ZrC ternary ceramic phases (0%, 5%, 10%, 15%, respectively ) on TC4 surface by 4 kW high-power Laser4000 semiconductor laser with laser cladding technology. After the cladding, the cladding parts were cut, polished and corroded to prepare metallographic samples. The macroscopic morphology, microstructure and properties of the cladding coatings with different material components were compared and analyzed by EM electron microscope, SEM scanning electron microscope, EDS energy spectrometer and XRD diffractometer. The macro hardness value of the cladding layer was measured by TH120 A Leeb hardness tester, and the micro hardness change rule of the cladding sample section was analyzed by Qness type Vickers microhardness tester. The results show that the addition of ternary ceramic phase makes the cladding layer and the substrate form a good metallurgical bonding, and the substrate and the cladding layer have a clear smooth boundary. The cladding layer is mainly composed of α+β acicular martensite matrix and precipitated rod-like and block-like α phases. The cladding layer of the ternary ceramic reinforcement phase with a mass fraction of 15% is composed of block-like crystals, and the grains are the most coarse. For the coating of the ternary ceramic reinforcement phase with a mass fraction of 5% and 10%, the size of the rod-like and block-like α phases is significantly reduced, the grains are obviously refined, and the structure is more uniform and dense. The main components of the columnar and massive α phases in the cladding layer are Ti and trace Al, Zr, Hf and V elements. The acicular martensite of the coating contains high Al, Zr, Ta and V elements, and the black β phase between the crystals contains trace Zr and Ta elements. It is found that Hf and Ta elements usually exist in different phases. The hardness of the specimens is improved after laser cladding. When the mass fraction of the ternary ceramic addition is 10%, the grain of the cladding layer is the smallest, the distribution is uniform, and the hardness is the highest, reaching 715 HV, which is 2.31 times that of TC4 substrate.

With the advancement of urbanization and the transformation of the old city, the production and stock of construction waste in China are ever increasing, with waste clay bricks accounting for 50%~70%. It has been found that recycled brick powder has the potential as a supplementary cementitious material, but it can lead to a significant reduction in the mechanical properties of cement-based materials. In order to explore the effect of particle size on the activity of recycled brick powder and the hydration kinetics of cement, this study prepared recycled brick powder with different particle sizes by high-energy ball milling. The physical and chemical properties and hydration activity of recycled brick powder were characterized. The effect of particle size of recycled brick powder on the hydration process, microstructure and mechanical properties of recycled brick powder-silicate cement system was analyzed. Based on the Krstulovic-Dabic model, the hydration kinetic parameters of the system were obtained to realize the quantitative evaluation of the hydration process. The results show that with the decrease of the particle size of the recycled brick powder, the lattice distortion of the silicon-aluminum mineral becomes larger and the surface binding energy decreases, resulting in an increase in its hydration activity. The early hydration of recycled brick powder mainly plays a physical filling role, which can accelerate the early hydration of recycled brick powder-cement system and improve the hydration degree of crystallization nucleation and crystal growth→phase boundary reaction→diffusion process. With the decrease of particle size of recycled brick powder, the starting time of pozzolanic reaction is advanced and the degree of pozzolanic reaction is higher. Finally, the later strength of cement mixed with 30% fine-grained recycled brick powder exceeds that of pure cement. This paper lays a foundation for the efficient application of recycled brick powder in cement-based materials.

Fatigue failure is the main failure mode of mechanical structure, and the premise of the fatigue life prediction on mechanical structure is to obtain S-N curves of high precision based on test data. However, the fatigue test data often show large dispersion, so it is more appropriate to use probabilistic fatigue life curve (P-S-N) to describe the stress cycle relationship. To overcomes the limitations of the existing classical machine learning model which can only give the determined value of fatigue life but cannot quantify its dispersion in the analysis of material fatigue data, this study proposed a P-S-N curve estimation method for metal materials based on Bayesian neural network (BNN) model. Firstly, the weight parameters of the traditional neural network model were regarded as random variables, and the posterior distribution of the weight parameters was estimated by the BNN model according to the training samples. Then, considering that the existing posterior distribution estimation methods are easy to underestimate the uncertainty of weight parameters, this paper introduced a black-box alpha (BB-α) algorithm based on α divergence to estimate the posterior distribution of the weight parameters. Finally, the BNN model was used to analyze the fatigue data of 2524-T3 aluminum alloy, 2024-T4 aluminum alloy and S420MC steel. The results show that BNN can be used as an effective and robust model for fatigue data fitting and uncertainty quantification. Meanwhile, the BNN model based on BB-α algorithm can give a more accurate uncertainty quantification results of fatigue data.

The cement industry is a high energy consuming industry, and the use of mineralizers in the calcination process of cement clinker is an effective energy-saving method. Using solid waste as a mineralizer can also turn waste into treasure and achieve its resource utilization. With pyrite tailings as mineralizer, this study prepared Portland cement clinker with 0, 1.5%, 2.0% and 2.5% SO₃ at calcination temperature of 1 350 ℃, 1 400 ℃ and 1 450 ℃. Thermal analysis, X-ray diffraction (XRD), polarizing microscope, and other methods were used to analyze the effects of SO₃ addition on the calcination process, mineral composition, petrographic structure, and physical properties of the clinker. The results show that the best effect is achieved when the content of SO₃ is 2.0%. Under this proportion, the content of f-CaO in cement clinker decreases from 1.84% to 1.18%, which can significantly improve the burnability of raw meal. The addition of pyrite tailings can reduce the initial and peak temperatures of CaCO₃ decomposition in raw meal, and form two transition phases of calcium sulphosilicate (2C₂S·CaSO₄) and calcium sulphoaluminate (4CaO·3Al₂O₃·SO₃) at low temperature. This reduces the temperature of liquid phase by 35 ℃, promoting the formation and development of clinker minerals, and has a significant mineralization effect. The cement clinker obtained by calcination with pyrite tailings has good performance, and its compressive strength after curing for 3 days and 28 days is 33.1 and 61.8 MPa, respectively.