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As an ideal energy source, hydrogen is highly susceptible to spontaneous ignition once leaked, which is an urgent issue that needs to be addressed. Based on the shock tube model, this paper investigates flame propagation under various pressures, tube lengths, and diameters by employing the LES approach and a detailed hydrogen/air combustion mechanism. The results indicate that within the tube, the ignition kernels gradually evolve into tulip flames when specific conditions are satisfied. As pressure and tube length increase, the likelihood of forming a complete flame rises significantly; with the increase of tube diameter, the flame front is flatter and the flame intensity is more uniformly distributed. Furthermore, this paper develops a model to predict the formation of a complete flame: Pb/Pa=570.64(L/D)−0.6. Outside the tube, once the intact flame passes out of the tube and evolves into a jet flame, structures such as flame envelopes and jet vortices will appear. Higher release pressures make it more difficult for the flame to propagate steadily, whereas increasing tube length and diameter promotes combustion and sustains the flame outside the tube.

Experimental tests and molecular dynamics simulations were employed to investigate the effect of Ni concentration on the toughness and hydrogen embrittlement resistance of pipeline steel. A slow strain rate test (SSRT) was conducted under both air and electrochemical hydrogen charging conditions. The results indicate that the tensile toughness, impact toughness, and hydrogen embrittlement resistance of steel increase when Ni concentration is less than 1 %, followed by a decrease when Ni concentration exceeds 1 %. Additionally, an increase in Ni concentration leads to a reduction in both the free surface energy and stacking fault energy of Fe-Ni alloys. Since Ni has a greater influence on the stacking fault energy, dislocation emission is facilitated, which aids in releasing strain energy. However, when the Ni concentration surpasses 1 %, the formation of carbides, which are sensitive to hydrogen embrittlement, occurs. Consequently, when the Ni concentration is higher than 1 %, the toughness and hydrogen embrittlement resistance of steel decrease.

Abstract Superhydrophobic coatings show great application potential in many fields, but they have not been widely used due to poor stability. A Ni-PTFE-SiC composite coating was proposed in this paper. Firstly, the Ni-PTFE-SiC coating structure was designed by molecular dynamics simulations. The feasibility of superhydrophobic effect of this structure and the adsorption stability of the composite coatings were proved. This approach can also be used to avoid trial and errors when selecting other similar candidate substances. Then, the Ni-PTFE-SiC superhydrophobic coatings were successfully prepared by composite electrodeposition, with the water contact angle of more than 155° and the sliding angle of close to 0°. The effects of current density, deposition time and nanoparticle concentration on the wettability and morphology of the coatings were also investigated. Through comparative experiments, the best preparation parameters were: PTFE 14 g L−1, SiC 6 g L−1, primary current density 7 A dm−² (10 min) and secondary current density 15 A dm−² (5 min). This preparation method doesn’t need additional modification with low surface energy substances like the traditional preparation process, and greatly improves the corrosion resistance, wear resistance and durability of the coatings.

Superamphiphobic coatings have shown great potential in many fields such as with their anti-corrosion, high-temperature resistance, self-cleaning, and drag reduction properties. However, due to the poor stability of their coatings, it is difficult to apply them on a large scale. In this paper, two kinds of SiO2 particles and nickel were co-deposited on the surface of steel to construct a micro/nano dual-scale structure by composite electrodeposition. The surface of the coating was then fluorinated with the low-surface-energy material 1H,1H,2H,2H-Perfluorodecyltriethoxysilane (AC-FAS) to prepare a Ni-SiO2 superamphiphobic coating. The coating has a water contact angle of 159° and an oil contact angle of 151°. The effect of nanoparticle concentration on the wettability and surface morphology of the coating was systematically studied. Comparative experiments revealed that the optimal micro/nanoparticle concentrations were 8 g/L of 20 nm SiO2 and 2 g/L of 1 μm SiO2. This preparation method greatly improves the corrosion resistance, wear resistance, chemical stability, and high-temperature resistance of the coating.

As a paradigm of clean energy, hydrogen is gradually attracting global attention. However, its unique characteristics of leakage and autoignition pose significant challenges to the development of high-pressure hydrogen storage technologies. In recent years, numerous scholars have made significant progress in the field of high-pressure hydrogen leakage autoignition. This paper, based on diffusion ignition theory, thoroughly explores the mechanism of high-pressure hydrogen leakage autoignition. It reviews the effects of various factors such as gas properties, burst disc rupture conditions, tube geometric structure, obstacles, etc., on shock wave growth patterns and autoignition characteristics. Additionally, the development of internal flames and propagation characteristics of external flames after ignition kernels generation are summarized. Finally, to promote future development in the field of high-pressure hydrogen energy storage and transportation, this paper identifies deficiencies in the current research and proposes key directions for future research.

In this study, a near-infrared light-responsive shape memory self-healing coating was prepared using epoxy resin (EP) and GO-PCL/PPy polymer composite as the shape memory matrix and photothermal conversion polymer agent, respectively. Special attention was paid to self-healing performance and corrosion resistance of the coating. The results indicated that the optimal performance of polypyrrole was achieved at the surfactant-pyrrole ratio of 2:1 and the polymerization time of 5 h. The incorporation of GO-PCL/PPy polymer into epoxy composite led to an increase in thermal conductivity of the whole coating. Additionally, the best photothermal conversion effect on epoxy resin was observed at the polymer content of 7 wt%, resulting in a shape recovery rate of 66.67% for the composite material. Moreover, the coating demonstrated the outstanding self-healing performance with a scratch-healing efficiency of up to 80%. Finally, the corrosion resistance of the coating was significantly improved compared to pure epoxy coatings.

Microcrack damage repair and microbial contamination prevention are two major challenges for anti-corrosion coatings on the surfaces of underwater installations. In this study, water-triggered self-healing microcapsules were combined with low-surface-energy fluoropolymers to prepare a bifunctional anti-corrosion coating with underwater self-healing and bio-fouling properties. The results showed that the prepared microcapsules had good mechanical, thermal, and environmental stability, with an average diameter of 153 μm and an encapsulation rate of 66.7%. When the microcapsule content in the coating was 8 wt%, the microcapsule dispersion performance and healing barrier effect of the composite coating were optimal, and the repair efficiency reached 81.6%. Furthermore, compared with the coating without microcapsules or graft fluoropolymers (PFG), the sample denoted as PFG18/4/IPDI-MC/ER showed the largest surface water contact angle and had the best protein inhibition rate of 87% when using bovine hemoglobin to detect the protein adsorption concentration on the coating surface.

FPSO is the main development model of deepwater oil field in South China Sea, and it has high requirements for the reliability of single-point mooring system. Therefore, the design investigation of inverse catenary of deepwater FPSO mooring suction pile was conducted. Meanwhile, a complete mathematical model for inverse catenary of suction pile was established based on the characteristics and mechanics of seabed soil, and a calculation method for the slack of inverse catenary was proposed. Besides, taking a deepwater FPSO project in the South China Sea as the research object, analysis on mooring under the designed survival condition (1 000-yr-RP) and the designed extreme condition (100-yr-RP) was performed based on the mooring load conditions required by classification societies to obtain the seabed mooring load. As shown by the evaluation results on design of embedded chain inverse catenary and its slack, the tension range of the embedded chain inverse catenary for suction pile of this FPSO mooring is 10 254 kN to14 075 kN, the load angle range is 16.2° to 30.1°, and the horizontal projection distance of the embedded chain is 47.33 m to 80.30 m. Further, the results based on different rules are close to each other for mutual verification. The final results of analysis and design could provide experience for similar FPSO projects.

In this paper, four lithological parameters, that is, thermal conductivity, particle size, porosity, and saturation, are investigated by combining experimental observations with numerical simulations to study the influence laws and mechanisms of action on the combustion process of methane hydrate sediments. The variations in combustion characteristics parameters such as flame height, effective combustion ratio, and dimensionless discharge water mass with the lithological parameters are studied. In addition, the combustion mechanism of lithologic parameters on methane hydrate deposits is revealed. Combining the experimental results and simulation calculations to optimize the combustion of methane hydrate sediments, it is recommended to use methane hydrate sediment samples with high saturation and low thermal conductivity, while the oxidant concentration and porosity of methane hydrate sediment samples should be increased.

X80 steel is extensively used in hydrogen environments and is susceptible to hydrogen embrittlement (HE). This paper studied the hydrogen-induced cracking (HIC) behavior in the coarse-grained heat-affected zone (CGHAZ) of X80 steel welds, through applying in situ hydrogen-charging tensile experiments, hydrogen permeation experiments, and various surface analysis techniques. It is shown that a few hydrogen atoms can significantly decrease a material’s elongation and reduction of area. When the heat input (HI) was 29.2 kJ/cm, the material had minor sensitivity to hydrogen embrittlement. The tensile fractures were ductile without hydrogen. However, the fracture surface exhibited brittle fracture with hydrogen. With increased HI, the HE fracture showed a transition of intergranular fracture→intergranular and transgranular mixed fracture→transgranular fracture. In the presence of hydrogen, the grain boundaries of elongated strips were prone to the formation of intergranular cracks under a tension load, and the hydrogen embrittlement resistance of the bulk lath bainite (LB) was weak. The hydrogen embrittlement susceptibility of pure granular bainite (GB) was lower. Fine LB and GB composite structures could remarkably inhibit intergranular cracks, giving the steel a superior resistance to hydrogen embrittlement.

The study of combustion in the plateau environment has gradually aroused the interest of scholars. Due to the particularity of the plateau environment, these plateau combustion experiments are usually carried out in artificial low-pressure chambers. The image processing of continuous flames has recently been widely used in scientific research and detection applications for various thermal and power devices. In this paper, three methods for selecting the optimal threshold for flame binarization images were investigated by using a flame video of horizontal diesel spray combustion in a low-pressure chamber. The results show that the binarization image with the threshold value selected by the two-peak method came closer to the actual flame's morphology. The maximum class difference method greatly increases the binarization area at the bottom of the flame, while the minimum error method significantly reduce the binarization area of the flame, especially with regard to the flame length. Finally, the mechanism of influence of the threshold selection method was analyzed from the perspective of the flame luminance and buoyancy of the horizontal jet flame. This work provides a better method of threshold selection for scientific research into simulating plateau combustion flames in low-pressure chambers, which has important engineering value and significance.

For the long-term service of X65/Incoloy 825 bimetallic composite pipe girth welds in the H2S environment, the corrosion damage behavior was investigated. Characterizations of welded joints were conducted by OM, SEM, XRD, and EDS. The pitting corrosion’s 3D surface morphology of welded joints in NACE-B solution saturated with H2S was investigated. The results show that composition segregation occurs in the welding process, and the Laves phase appears between dendrites, which lead to the decrease in corrosion resistance. The maximum depth of the corrosion pit is 2.46 μm after 30 days, 4.54 μm after 60 days, and 10.94 μm after 180 days. The cell automata (CA) model of corrosion damage was established based on the MATLAB program, and the basic elements of the cell automata model were determined. Through the simulation of the electrochemical reaction and diffusion process, the influence of different parameters of the pitting corrosion morphology was determined. The simulation results were compared with experimental data, which are available for the prediction of the morphology and size of the corrosion pits on the sample surface after 300 days. The results will be beneficial for the long-term service of the bimetallic composite pipe.

Developing powerful immunoassays for sensitive and real-time detection of targets has always been a challenging task. Due to their advantages of direct readout, controllable sensing, and low background interference, photothermal immunoassays have become a type of new technology that can be used for various applications such as disease diagnosis, environmental monitoring, and food safety. By modification with antibodies, photothermal materials can induce temperature changes by converting light energy into heat, thereby reporting specific target recognition events. This article reviews the design and application of photothermal immunoassays based on different photothermal materials, including noble metal nanomaterials, carbon-based nanomaterials, two-dimensional nanomaterials, metal oxide and sulfide nanomaterials, Prussian blue nanoparticles, small organic molecules, polymers, etc. It pays special attention to the role of photothermal materials and the working principle of various immunoassays. Additionally, the challenges and prospects for future development of photothermal immunoassays are briefly discussed. [ABSTRACT FROM AUTHOR]

Lead is one of the heavy metals that is toxic and widely distributed in the environment, and children are more sensitive to the toxic effects of lead because the blood–brain barrier and immune system are not yet well developed. The objective of the study was to investigate the clinical characteristics of lead poisoning in children aged 0∼6 years in a hospital in Guangxi, and to provide scientific basis for the prevention and treatment of lead poisoning. We collected and analyzed the clinical data of 32 children with lead poisoning admitted to a hospital in Guangxi from 2010 to 2018. The results showed that most of the 32 cases presented with hyperactivity, irritability, poor appetite, abdominal pain, diarrhea, or constipation. The hemoglobin (HGB), mean corpusular volume (MCV), mean corpuscular hemoglobin (MCH), and hematocrit (HCT) of the lead-poisoned children were all decreased to different degrees and were below normal acceptable levels. Urinary β2-microglobulin was increased. Blood lead levels (BLL) decreased significantly after intravenous injection of the lead chelator, calcium disodium edetate (CaNa2-EDTA). In addition, HGB returned to normal levels, while MCV, MCH, and HCT increased but remained below normal levels. Urinary β2-microglobulin was reduced to normal levels. Therefore, in this cohort of children, the high-risk factors for lead poisoning are mainly Chinese medicines, such as baby powder. In conclusion, lead poisoning caused neurological damage and behavioral changes in children and decreased erythrocyte parameters, leading to digestive symptoms and renal impairment, which can be attenuated by CaNa2-EDTA treatment. [ABSTRACT FROM AUTHOR]