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To promote the resource utilization of steel slag and improve the production process of steel slag in steelmaking plants, this research studied the characteristics of three different processed steel slags from four steelmaking plants. The physical and mechanical characteristics and volume stability of steel slags were analyzed through density, water absorption, and expansion tests. The main mineral phases, morphological characteristics, and thermal stability of the original steel slag and the steel slag after the expansion test are analyzed with X-ray diffractometer (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TG) tests. The results show that the composition of steel slag produced by different processes is similar. The main active substances of other processed steel slags are dicalcium silicate (C2S), tricalcium silicate (C3S), CaO, and MgO. After the expansion test, the main chemical products of steel slag are CaCO3, MgCO3, and calcium silicate hydrate (C-S-H). Noticeable mineral crystals appeared on the surface of the steel slag after the expansion test, presenting tetrahedral or cigar-like protrusions. The drum slag had the highest density and water stability. The drum slag had the lowest porosity and the densest microstructure surface, compared with steel slags that other methods produce. The thermal stability of steel slag treated by the hot splashing method was relatively higher than that of steel slag treated by the other two methods.

Bronze artifacts unearthed by archaeologists are affected by underground burial environment and other factors, and most of them have different degrees of corrosion. Bronze artifacts unearthed by archaeologists have different degrees of mineralization. Establishing a data analysis database for basic structure and disease analysis of mineralized bronze artifacts is a necessary prerequisite for developing targeted reinforcement materials and realizing accurate protection. Based on the characteristic analysis of the mineralized bronzes, this paper systematically analyzed the mineralization and disease characteristics of the mineralized bronzes by Confocal Super Depth-of-Field Microscope(CSDTM), scanning electron microscopy (SEM), energy spectrum analysis(EDS) and XRD, and compared and analyzed the microscopic morphology, composition and phase structure of the bronzes under the same burial environment, so as to provide support for subsequent targeted protection and reinforcement.

To investigate the behaviors and processes of aluminum agglomeration, a study was conducted on the ignition, combustion and agglomeration properties of fuel-rich propellant containing Al/Mg particles additives. This research employed scanning electron microscopy along with optical visualization experimental technique within a small-scale sealed laser ignition apparatus. The results indicate that the agglomeration of aluminum particles occurs not only on the burning surface of the composite propellant but also following detachment from it. Upon detachment, these agglomerates undergo various processes, including coalescence, expansion, ejection, and fragmentation. It is found that the content of metal particles significantly affects both combustion and agglomeration properties. Under the condition of constant total metal content of 40%, the burning rate increases by 7.7% on average when the aluminum particle content increases from 20 to 35%. A novel model for predicting agglomeration size has been developed, clearly illustrating the influence of composition and burning rate on the agglomeration size after detachment from the burning surface.

Gestational diabetes mellitus (GDM) influences adverse maternal and fetal outcomes. Nutritional therapy and exercise are the first steps to maintain normal glucose levels. During pregnancy, metabolic status influences placental development. This systematic review focused only on the morphology of the placenta and its microscopic changes in GMD under dietary therapy. A systematic search was performed on the main databases from inception to September 2024 (PROSPERO ID: CRD42024581621). Only original articles on GDM in diet and exercise treatment that reported at least one outcome of interest (microscopic features and macroscopic morphology of the placenta) were included. A total of 716 studies were identified, and nine met the inclusion criteria. The analysis confirmed that despite dietary control, some morphological changes in the placenta, including villus immaturity, chorangiosis, and fibrinoid necrosis, occurred at a different rate. In addition, the included studies reported an increase in placental weight in the diet-controlled GDM group. Therefore, the results of the present qualitative analysis show that pregnant women with diet-controlled GDM, despite adequate glycemic control, abnormal placental development may persist. Our findings remark on the importance of the correct diet-managed GDM pregnancy monitoring due to the placental morphology abnormalities related to GMD.

Aiming at the problem that ordinary cement concrete is subjected to damage in heavy saline soil areas in China, a new type of magnesium oxychloride cement concrete is prepared by using the gelling properties of magnesium oxychloride cement in this study, and the erosion resistance of the synthesized magnesium oxychloride cement concrete in concentrated brine of salt lakes is studied through the full immersion test. The effects of concentrated brine of salt lakes on the macroscopic, microscopic morphology, phase composition and mechanical properties of magnesium oxychloride cement concrete are investigated by means of macro-morphology, erosion depth, SEM, XRD and strength changes. The salt erosion resistance mechanism of magnesium oxychloride cement concrete is revealed. The results demonstrate that under the environment of full immersion in concentrated brine of salt lakes, there is no macroscopic phenomenon of concrete damage due to salt crystallization, and the main phase composition is basically unchanged. The microscopic morphology mostly changes from needle-rod-like to gel-like. Due to the formation of a new 5·1·8 phase on the surface layer and the increase in compactness, its compressive strength has a gradual increase trend. Based on the engineering application of magnesium oxychloride cement concrete, it is further confirmed that magnesium oxychloride cement concrete has excellent salt erosion resistance and good weather resistance, which provides theoretical support for future popularization and application.

This study investigates how poly (vinyl alcohol) (PVA) influences melamine–urea–formaldehyde (MUF) resin, particularly regarding tensile properties, bonding strength, water resistance, curing temperature, chemical structure, and microscopic morphology. By altering the PVA content, we observed changes in the tensile strength and elongation of MUF resin. The tensile strength peaked at a 2% PVA addition. PVA significantly enhanced the dry, cold water, and boiling water bonding strengths of MUF resin, with the most notable effect at a 10% addition. A low PVA addition (2%) notably improved the water resistance of glued wood. Differential scanning calorimetry revealed that PVA increased the curing temperature of MUF resin, though excessive PVA led to a decrease. Nuclear magnetic resonance analysis showed changes in chemical bonds after PVA modification, indicating increased polymerization. X-ray diffraction and scanning electron microscopy analyses further confirmed the effects of PVA on the crystal structure and microscopic morphology of MUF resin, with modified resins exhibiting higher toughness fracture characteristics. These findings suggest that PVA can effectively enhance the overall performance of MUF resin, making it more suitable for applications of glued wood.

In order to solve issues related to bridge girders, expansion devices and road surfaces, as well as other structures that are prone to fatigue failure, a kind of fatigue-resistant elastic polyurethane concrete (EPUC) was obtained by adding waste rubber particles (40 mesh with 10% fine aggregate volume replacement rate) to conventional engineering polyurethane concrete (PUC). Based on the preparation and properties of EPUC, its constitutive relation was proposed through compression and tensile tests; then, a scanning electron microscope (SEM), an atomic force microscope (AFM) and a 3D non-contact surface profilometer were used to study the failure morphology and micromechanisms of EPUC. On this basis, four-point bending fatigue tests of EPUC were carried out at different temperature levels (−20 °C, 0 °C, 20 °C) and different strain levels (400 με~1200 με). These were used to analyze the stiffness modulus, hysteresis angle and dissipated energy of EPUC, and our results outline the fatigue life prediction models of EPUC at different temperatures. The results show that the addition of rubber particles fills the interior of EPUC with tiny elastic structures and effectively optimizes the interface bonding between aggregate and polyurethane. In addition, EPUC has good mechanical properties and excellent fatigue resistance; the fatigue life of EPUC at a room temperature of 600 με can grow by more than two million times, and it also has a longer service life and reduced disease frequency, as well as fewer maintenance requirements. This paper will provide a theoretical and design basis for the fatigue resistance design and engineering application of building materials. Meanwhile, the new EPUC material has broad application potential in terms of roads, bridges and green buildings.

Apart from the widely discussed pineapple leaf fibers, normally referred to as PALF, fibers from other parts of the plant also exist, particularly those in the fruit crown, which are known as pineapple crown leaf fibers (PCLF). In this work, PCLF were characterized using thermogravimetric analysis (TGA), Fourier transform IR spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results indicated that the properties of PCLF do not greatly differ from those observed for PALF. In particular, a cellulose content of over 67% was observed, with approximately 76% crystallinity. The main degradation phenomena of the fibers took place between 230 and 380 °C, peaking at 324 °C, which is in line with observations in other fibers which have similar cellulose and crystalline contents. There was 13.4% residue at 680 °C. Bare mechanical retting of PCLF, although not allowing a full and thorough degumming, which would only be achieved through more aggressive chemical treatment, enabled aspect ratios of over 103 to be obtained. This indicates some potential for their application as short fibers in composites. In this respect, the considerable roughness of PCLF when compared to other leaf-extracted fibers, and in particular when compared to PALF, could suggest an ability to obtain a sufficiently sound fiber–matrix interface.

Liquid metal embrittlement is a phenomenon in which the mechanical properties of a metallic material are significantly reduced after contact with liquid metal, and the microscopic mechanism of this phenomenon is still controversial. The grain boundary penetration mechanism has recently been widely recognized, but the theory is still deficient. To refine the theory of grain boundary penetration, in this paper, the liquid metal embrittlement mechanism of aluminum by gallium is obtained by in situ EBSD, combining it with the fracture morphology features and comparing the differences of the microscopic feature changes and the crack evolution process during the in situ tensile process of embrittled and untreated aluminum specimens. The results show that the fracture elongation of aluminum decreased by 60% after being embrittled by liquid gallium at 80 °C for 40 min, and the gallium atoms entering the aluminum interior decreased the grain boundary cohesion while promoting dislocation emission. Combining the experimental results and previous studies, we divide the fracture of aluminum after liquid metal embrittlement into three stages, namely, the grain boundary penetration stage, the local fracture stage, and the integral failure stage.

As a common building insulation material, foamed concrete has been widely used in engineering practice. However, the contradiction between compressive strength and thermal conductivity has become the main problem limiting the development and application of foamed concrete. Therefore, high-performance foam concrete (HPFC) with high compressive strength and low thermal conductivity was prepared by using graphene oxide (GO), fly ash, and polypropylene (PP) fiber as the main admixtures, and taking compressive strength, thermal conductivity, and microstructure as the main indices. Scanning electron microscopy, X-ray diffraction (XRD), and thermogravimetry–differential scanning calorimetry (TG-DSC) were employed to examine the mechanisms of HPFC. The results showed that when the content of fly ash was 25–35 wt%, PP fiber was 0.2–0.4 wt%, and GO was 0.02–0.03 wt%, the FC’s compressive strength increased by up to 38%, and its thermal conductivity reduced by up to 3.4%. Fly ash improved the FC’s performance mainly through filling, pozzolanic activity, and slurry fluidity. PP fiber enhanced the performance of FC mainly through bridging cracks and skeletal effects. The addition of GO had no significant impact on the type, quantity, or hydration reaction rate of the hydration products in these cement-based materials, and mainly improved the FC’s microstructural compactness through template action and crack resistance, thereby improving its performance.