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.
•An anticorrosive coating with underwater self-repairing and anti-fouling performance has been prepared.•The repairing efficiency of microcapsule with the content of 8 wt% in the composite coating reached 81.6%.•The protein inhibition rate of the composite coating detected by bovine hemoglobin reached 87%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Improving the application of nanomaterials has always been a research hotspot in the field of energetic materials (EMs) due to their obvious catalytic effect on the EMs, especially the uniformly ...dispersed nanomaterials. However, few studies have reported the dispersion of nanomaterials. In this study, the dispersity and mixing uniformity of nano-CuCr2O4 was evaluated based on the difference of solid UV light absorption between the nano-catalytic materials and EMs. The nano-CuCr2O4/ultrafine AP composites with different dispersity of nano-CuCr2O4 were prepared by manual grinding and mechanical grinding with different grinding strength and griding time. And then, the absorbance of different samples at 212 nm was obtained by solid UV testing due to the high repeatability of the absorbance at 210–214 nm for three parallel experiments, and the dispersity of different samples was calculated through the established difference equation. Furthermore, the samples were characterized by XRD, IR, SEM, EDS, DSC and TG-MS, which confirmed that different mixing methods did not change the structure of the samples (XRD and IR), and the mixing uniformity improved with the increase of grinding strength and grinding time (SEM and EDS). The scientificity and feasibility of the difference equation were further verified by DSC. The dispersity of nano-CuCr2O4 exhibits a positive intrinsic relationship with its catalytic performance, and the uniformly dispersed nano-CuCr2O4 significantly reduces the thermal decomposition temperature of ultrafine AP from 367.7 to 338.8 °C. The TG-MS patterns show that the dispersed nano-CuCr2O4 advanced the thermal decomposition process of ultrafine AP by about 700 s, especially in the high temperature decomposition stage, and the more concentrated energy release characteristic is beneficial to further enhance the energy performance of AP-based propellants. The above conclusions show that the evaluation method of dispersity based on solid UV curves could provide new ideas for the dispersity characterization of nano-catalytic materials in EMs, which is expected to be widely used in the field of EMs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
During the operation of the natural gas longdistance pipeline, the impact of various factors will inevitably lead to corrosion problems, which will cause serious environmental pollution. It can be ...seen that accurate prediction of the corrosion rate of the pipeline is very important to ensure the safety of the pipeline. In this study, a new gray correlation analysis method was introduced to deeply analyze the influencing factors of the corrosion rate in the natural gas long-distance pipeline. The corrosion rate and related influencing factors in the natural gas pipeline were used as training data sets, and an improved pigeon group algorithm (PIO) was used. The parameters of the support vector machine (SVM) algorithm are optimized to establish an intelligent model for predicting the corrosion rate in the natural gas pipeline, which lays the foundation for the safe operation of the natural gas pipeline. Research shows that although there are relatively many factors affecting the corrosion rate in natural gas long-distance pipelines, the CO2 content, H2S content, and temperature in natural gas are the three important factors that affect the corrosion rate in natural gas pipelines. The maximum error of the RBF- PIO-SVM combined model to predict the internal corrosion rate of natural gas long-distance transmission is 5.36%, and the average relative error is 1.08%. The prediction result is relatively high, which proves that the prediction model of the internal corrosion rate of the natural gas pipeline proposed in this research has a strong advanced nature. This study proves that using the RBF-PIO-SVM model to predict the internal corrosion rate of natural gas long-distance pipelines has relatively small errors and is highly feasible. It can effectively guide countermeasures to prevent pipeline corrosion and protect the environment.
5-Demethylnobiletin (5-DMN), a hydroxylated polymethoxyflavone (OH-PMF) identified in aged citrus peels, has demonstrated health benefiting effects in previous studies. 5-DMN undergoes ...biotransformation in vivo, yielding 5,3'-didemethylnobiletin (5,3'-DDMN), 5,4'-didemethylnobiletin (5,4'-DDMN) and 5,3',4'-tridemethylnobiletin (5,3',4'-TDMN). However, the anti-cancer effects of 5-DMN and its in vivo metabolites against HepG2 cells remain unclear. In this study, an efficient chemical synthetic method was developed to obtain 5-DMN and its 3 metabolites, and their molecular structures were confirmed by 1H NMR and LC-MS. Cytotoxicity, cell cycle arrestment, apoptosis and caspase-3 expression were investigated to evaluate the anti-liver cancer effects of these OH-PMFs on HepG2 cells. The results showed that all 4 compounds inhibited the proliferation of HepG2 cells in a concentration-dependent manner. Their anti-proliferative activity was exerted through inducing G2/M phase arrestment, cell apoptosis and promoting expression of a key apoptotic protein called cleaved caspase-3. Our results indicated that 5,3'-DDMN and 5,3',4'-TDMN showed a stronger inhibitory activity on cell proliferation than 5-DMN, followed by 5,4'-DDMN. The expression of cleaved caspase-3 was the highest in cells treated with 5,4'-DDMN, implying that the apoptosis induced by other OH-PMFs might be mediated by other apoptotic execution proteins. Our research reveals the application potential and scientific evidence for the production and functionality of OH-PMFs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Alteration in the environmental conditions will cause a reversed reaction between o/w emulsion and w/o emulsion that has similar advantages of different liquids form on the reversible invert ...emulsion. The reversible phase inversion of the emulsion has a benefit of dealing with drilling cutting, so the reversible invert emulsion also can be thought used as a drilling fluid. The phase inversion from w/o emulsion to o/w emulsion can be divided into three stages. They are w/o emulsion, w/o/w emulsion, and o/w emulsion. In the w/o emulsion stage, the structure appeared among water droplets when the percentage of the HCl solution (5%) was less than 0.375%. In the w/o/w emulsion stage, the structure among water droplets existed at the beginning of this stage; however, the internal phase and the external phase can interchange their positions during the process. In the third stage, the structures among droplets of the emulsion would be broken and the degree of the dispersion of the oil droplet in the emulsion would increase. The changes in the microstructure, conductivity, electrical stability, standing stability, and the viscosity of the emulsion, which have edified among droplets in the process from w/o emulsion to o/w emulsion, were studied. The result of the microstructure microscopic observation agrees with the result of the electrical stability and viscosity experiments. Moreover, the internal phase and the external phase can interchange positions during the process.
A heat transfer model of a single U-shaped vertical buried pipe similar to an actual scenario is established, and the accuracy of the model is verified by experiments. The model is used to analyze ...the heat transfer performance of vertical buried pipe heat exchangers with well depths of 200, 160, 120, and 80 m. This includes the heat transfer per unit well depth, temperature change of the well wall and fluid along the pipe length, heat transfer coefficient, and section heat transfer validity. With the increase in well depth, the heat exchange per unit well depth decreases, and the proportion of heat exchange in the inlet section to the total heat exchange increases. When the well depths are 200, 160, 120, and 80 m, the last 10 m pipe sections have 30, 40.3, 53.7, and 66.4% of the heat exchange efficiencies of the initial 10 m pipe section, respectively. To obtain a reasonably effective well depth of a single U-shaped vertical buried pipe, it is necessary to comprehensively consider the heat exchange per unit well depth, the temperature difference between the well wall and the fluid, and the energy efficiency of the buried pipe section. Moreover, it should be analyzed in combination with economic factors.
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IJS, KILJ, NUK, PNG, UL, UM, UPUK
The oil and gas gathering and transportation system is an important link in the safe production and application of oil and gas. The gathering and transportation pipelines are prone to corrosion and ...damage, which leads to oil and gas leakage and serious environmental pollution. Experimental simulation study is performed on the under-scale corrosion of metal pipelines and equipment in oil and gas gathering and transportation system. Simulation of under- scale corrosion behavior through dynamic voltage polarization experiments is carried out, by using time-domain analysis and frequency-domain analysis of electrochemical noise spectrum, to study the inducing factors of under-scale corrosion. Then, through the fitting the noise power spectral density by fast Fourier transformation of the noise spectrum (SPD) curve and corrosion characteristic parameters, we study the internal relationship between the subfouling local corrosion characteristic parameters and corrosion. The results show that both high salinity and high Cl- in the corrosive medium will catalyze the under-scale corrosion. After the under-scale corrosion is formed, the potential noise will slowly increase, and the current noise will slowly decrease. With the increase of the concentration of Cl-, the noise resistance of carbon steel decreases, the current standard deviation Sx becomes larger, the transient peak of the noise spectrum increases significantly, the local corrosion index is closer to 1, the slope k of the high-frequency linear part becomes larger, and the corrosion is intensified. Therefore, the on-site in situ monitoring of local corrosion under the scale can be achieved by detecting the local corrosion characteristics of the metal, which is of great significance for the research on the mechanism of the under-scale corrosion behavior of the metal, corrosion protection, environmental protection, and safety warning.
The coupling of solid-phase extraction (SPE) using bamboo charcoal (BC) as an adsorbent with a monolithic column-high performance liquid chromatography (MC-HPLC) method was developed for the ...high-efficiency enrichment and rapid determination of 16 polycyclic aromatic hydrocarbons (PAHs) in water. Key influence factors, such as the type and the volume of the elution solvent, and the flow rate and the volume of the sample loading, were optimized to obtain a high SPE recovery and extraction efficiency. BC as an SPE adsorbent presented a high extraction efficiency due to its large specific surface area and high adsorption capacity; MC as an HPLC column accelerated the separation within 8 min because of its high porosity, fast mass transfer, and low-pressure resistance. The calibration curves for the PAHs extracted were linear in the range of 0.2-15 µg/L, with the correlation coefficients (r2) between 0.9970-0.9999. This method attained good precisions (relative standard deviation, RSD) from 3.5 to 10.9% for the standard PAHs I aqueous solutions at 5 µg/L; the method recoveries ranged in 52.6-121.6% for real spiked river water samples with 0.4 and 4 µg/L. The limits of detection (LODs, S/N = 3) of the method were determined from 11 and 87 ng/L. The developed method was demonstrated to be applicable for the rapid and sensitive determination of 16 PAHs in real environmental water samples.
Recently, the widespread use of nanocatalytic materials has contributed to an enormous improvement in the performance of energetic materials, especially, highly dispersed nanomaterials. However, the ...lack of quantitative methods for analyzing the dispersion of nanomaterials limits their further widespread use. Although various techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), etc. are used to analyze the relative dispersion of nanomaterials, it is not possible to quantitatively analyze their dispersion. Therefore, there has been an effort to develop new methods for the quantitative analysis of nanocatalytic materials. Fortunately, we were able to analyze the dispersion of nanocatalytic materials using the difference in their UV absorbance. More importantly, we established the corresponding difference equation to quantify the dispersion of nanocatalytic materials, which is capable of quantifying the dispersion of nano-Fe2O3 in nano-Fe2O3–ultrafine AP composites. The accuracy of the difference equation was verified using a variety of techniques and the desired results were obtained. Based on the above conclusions, the quantitative analysis method for the dispersion of nanomaterials that we established is expected to be widely used and promote the development of energetic materials.