Preparing super-hydrophobic surfaces with additive manufacturing (AM) and multi-step processes improves corrosion resistance of Al alloys. But the incorporation of dissimilar metals accelerates ...matrix corrosion, additive polymers cannot offer a long-term structural stability, and multi-step methods are complicated and costly. Hereon, stable micro-craters and nano-terraces on AA5052 sheet with enhanced water repellence and durable corrosion resistance are fabricated via low-cost subtractive manufacturing (SM) strategy. After fluoridation process, as-fabricated hierarchical structures possess highlighted self-cleaning and anti-adhesion capabilities. The following electrochemical test shows that the resultant surface effectively acts as a barrier against seawater infiltration suggesting superior anti-corrosion capacity. Meanwhile, the bacterial colony count test shows that the surface also possesses excellent resistance to microbiological adhesion. Such economic, efficient and environmental SM process is of great potential in fabricating multifunctional Al alloys with durable anti-corrosion, super-hydrophobic and bacteriostatic behaviors.
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•One-step electron discharge machining of stable hierarchical micro-nano structures is achieved.•The machined surface shows enhanced water-repellent, self-cleaning and anti-adhesion behaviors.•The surface acts as a durable barrier against seawater corrosion and bacteria adhesion.•Anti-corrosion mechanisms of various wetting states are systematically investigated.
Buckling and vibration analysis of functionally graded magneto-electro-thermo-elastic (FGMETE) circular cylindrical shell are carried out in the present work. The Hamilton principle, higher order ...shear deformation theory, constitutive equation considering coupling effect between mechanical, electric, magnetic, thermal are considered to derive the equations of motion and distribution of electrical potential, magnetic potential along the thickness direction of FGMETE circular cylindrical shell. The influences of various external loads, such as axis force, temperature difference between the bottom and top surface of shell, surface electric voltage and magnetic voltage, on the buckling response of FGMETE circular cylindrical shell are investigated. The natural frequency obtained by present method is compared with results in open literature and a good agreement is obtained.
nMg-xZn-Zr-SiC alloys are designed and fabricated with casting process.nAlloys display floccules, matrixes and second phases with discontinuous reticular structures.nMaterials guarantee fast ...decomposition of fracturing parts in chloride environment.nAlloys achieve excellent stability and pressure maintenance when decomposing.nCorrosion decomposition mechanism is also systematically investigated.
New-type magnesium alloy with prominent solubility and mechanical property lays foundation for preparing fracturing part in petroleum extraction. Herein, Mg-xZn-Zr-SiC alloy is prepared with casting strategy. Electrochemical and compression tests are conducted to assess the feasibility as decomposable material. Morphology, composition, phase and distribution are characterized to investigate decomposition mechanism. Results indicate that floccule, substrate component and reticulate secondary phase are formed on as-prepared surface. Sample also acts out enhanced compression strength to maintain pressure and guarantee stability in dissolution process. Furthermore, as decomposition time and zinc content increase, couple corrosion intensifies, resulting in gradually enhanced decomposition rate. Rapid sample decomposition is mainly due to basal anode dissolution, micro particle exfoliation and poor decomposition resistance of corroding product. Such work shows profound significance in preparing new-type accessible alloy to ensure rapid dissolution of fracturing part and guarantee stable compression strength in oil-gas reservoir exploitation.
Soil microorganisms play crucial roles in maintaining material circulation and energy flow in desert ecosystems. However, the structure and function of soil microorganisms in different forestlands ...are currently unclear, restricting the use of sand-fixing plants and the understanding of forest ecosystem functions. In this study, Artemisia ordosica, Caragana korshinskii, and Salix psammophila, three types of sand-fixing forests widely distributed in the Mu Us Sandy Land, were used to explore the effects of sand-fixing forests on soil physicochemical properties, soil enzyme activity, soil microbial biomass, microbial community structure, and inter-microbial species relationships. Soils of forestlands showed higher soil organic carbon (SOC), total phosphorus (TP), and total nitrogen (TN) contents than bare sandy land. The SOC in bare sandy soil was only 0.84 g kg−1, while it remained 1.55–3.46 g kg−1 in forestland soils. The TN in bare sandy land soil was 0.07 g kg−1, which was significantly lower than that in forestland soils (0.35–0.51 g kg−1). The TP in bare sandy soil was 0.18 g kg−1, significantly lower than that in forestland soils (0.46–0.69 g kg−1). Afforestation of bare sandy land improved soil microbial carbon and nitrogen contents and increased microbial enzyme activities of acid phosphatase and N-acetyl-β-D-glucosaminidase. Significant differences were observed between the three forestlands and bare sandy land in terms of soil microorganisms and community composition. With the establishment of a sand-fixing forest, the alpha diversity of soil bacteria significantly improved, whereas that of soil fungi remained stable. The bacterial community comprised 33 phyla, 106 classes, 273 orders, 453 families, and 842 genera. While five fungal phyla were detected by OTUs at a similarity of 97%, bacterial and fungal community structures were affected by the organic carbon content, sand particle content, soil pH, total nitrogen, and total phosphorus contents of soils. This study is helpful for vegetation construction and protection on sandy lands from the perspective of plant-microbe interactions.
A multifunctional aviation aluminum alloy with good superhydrophobicity and corrosion resistance was prepared by a two-step process of etching followed by polymer modification. Meanwhile, micro- and ...nanostructures formed on the processed sample. Compared with bare sample, the static liquid contact angle on the as-prepared sample was increased by 100.8°. Further polarization tests showed that the corrosion potential of such a sample increased, and the corrosion current density decreased obviously, thus suggesting that the corrosion resistance of the modified sample was significantly improved. The same conclusion was confirmed by subsequent impedance testing. The work is of great economic value and practical significance to enhance the corrosion resistance of aviation actuator materials and also lays a foundation for future hydrophobic application research in aeronautical engineering.
With the continuous development of China’s economy and society, people and the government have higher and higher requirements for food safety. Testing for food dopants and toxins can prevent the ...occurrence of various adverse health phenomena in the world’s population. By deploying new and powerful sensors that enable rapid sensing processes, the food industry can help detect trace adulteration and toxic substances. At present, as a common food safety detection method, lateral flow immunochromatography (LFI) is widely used in food safety testing, environmental testing and clinical medical treatment because of its advantages of simplicity, speed, specificity and low cost, and plays a pivotal role in ensuring food safety. This paper mainly focuses on the application of lateral flow immunochromatography and new technologies combined with test strips in food safety detection, such as aptamers, surface-enhanced Raman spectroscopy, quantum dots, electrochemical test strip detection technology, biosensor test strip detection, etc. In addition, sensing principles such as fluorescence resonance energy transfer can also more effective. Different methods have different characteristics. The following is a review of the application of these technologies in food safety detection.
In order to detect the QRS complexes locally in the microcontroller-based embedded system, a novel algorithm with lower computation burden is proposed by phase space reconstruction and box-scoring ...calculation. The method depends on the geometrical property of the ECG signal phase portraits. According to the time-delay method, one segment of the sampled 1-D ECG signal is embedded into a 2-D phase space. The phase space is divided into 2 M × 2 M grids, and each grid is called a box. The box gridding is implemented by numerically truncating the high M-bits from the digital data. The phase portraits of the sampled ECG signal in the phase space are therefore divided by these boxes. Since the trajectory points corresponding to the R-waves are located relatively far away from the diagonal line, boxes that crossed by the trajectory are flagged and valued according to its distance to the diagonal line. Correspondingly, the box-scoring of the ECG segment is obtained by summarizing the values of the flagged boxes. The location of the R-waves can then be found by finding peak values in the box-scoring time series. The proposed algorithm is suitable for real-time QRS complex detection in microcontroller-based wearable ECG acquisition devices.
In this paper, we designed and fabricated a liquid-repellent coating that features both superhydrophobicity and superoleophobicity, viz. Superamphiphobic properties, based on dual adhesive tape ...binding layer and 1H,1H,2H,2H-perfluorodecyltriethoxysilane modified aluminum oxide nanoparticles (Al2O3@PDFTES NPs). The constructed superamphiphobic coating presented non-wetting, high contact angles (CA), and low sliding angles (SA) towards various liquids with different surface tensions including water (CA = 167.6 ± 3.5°, SA = 2.9 ± 0.6°), glycerol (CA = 154.2 ± 2.7°, SA = 4.7 ± 0.4°), ethylene glycol (CA = 156.1 ± 2.4°, SA = 5.8 ± 0.2°), and peanut oil (CA = 155.2 ± 2.8°, SA = 6.5 ± 0.7°). The dynamic self-cleaning behaviors driven by water-, oil-, and hot water droplets verified the super-repellency, ultra-low surface energy, and interfacial adhesion force. The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements showed >250 mV positive shifting of Ecorr, 4 orders of magnitude lower Icorr, 7 orders of magnitude higher Rct and |Z| modulus values, demonstrating a significantly improved corrosion resistance of the superamphiphobic coating. The synergistic effect of the Al2O3@PDFTES NPs with low surface energy and the adhesive tape layer with interfacial binding force contribute to the development of stably self-cleaning and anti-corrosion superamphiphobic coating, which will be a potential candidate for protective interfacial materials for marine and industrial applications.
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During the co-evolution of viruses and their hosts, viruses have developed various strategies for overcoming host immunological defenses so that they can proliferate efficiently. Porcine reproductive ...and respiratory syndrome virus (PRRSV), a significant virus to the swine industry across the world, typically establishes prolonged infection
diverse and complicated mechanisms, which is one of the biggest obstacles for controlling the associated disease, porcine reproductive and respiratory syndrome (PRRS). In this review, we summarize the latest research on how PRRSV circumvents host antiviral responses from both the innate and adaptive immune systems and how this virus utilizes other evasion mechanisms, such as the manipulation of host apoptosis and microRNA. A thorough understanding of the exact mechanisms of PRRSV immune evasion will help with the development of novel antiviral strategies against PRRSV.
Three-phase, three-level Vienna rectifiers are widely used in power supplies for the advantages of high power density, low switching voltage stress and low grid side current harmonics. However, due ...to the presence of positive and negative sequence components under the unbalanced weak power grid, the control structure using the traditional proportional integral (PI) control is complicated and requires decoupling and multiple coordinate transformations, and it has longer dynamic response time. This paper presents an unbalanced current control strategy that combines improved sliding mode control (SMC) with new reaching law and multi proportional resonance (MPR) control of Vienna rectifier under unbalanced weak power grid. This paper establishes the mathematical model of Vienna rectifier under unbalanced weak current network. In the <inline-formula> <tex-math notation="LaTeX">\alpha \beta </tex-math></inline-formula> coordinate system, dual second-order generalized integrator (DSOGI) is used to separate the positive and negative sequence components of the voltage. Suitable sliding mode surfaces and sliding mode convergence laws were designed. Finally, the results of simulations and experiments were used to verify the effectiveness of the proposed method.
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