A spatial-temporal approach for corrosion prediction in time-varying marine environment

Exploration of Sargassum wightii: Extraction, Phytochemical Analysis, and Antioxidant Potential of Polyphenol

Background The marine environment, with its rich biodiversity and nutrient-dense ecosystems, offers immense potential for discovering novel pharmaceutical products. Sargassum wightii is a type of brown seaweed that is particularly abundant in sulfated polysaccharides and polyphenolic compounds. These compounds are renowned for their wide range of biological activities. The exploration of such marine resources is crucial for identifying new compounds that can be harnessed for pharmaceutical and nutraceutical applications. Aims and objectives The primary aim of this study is to explore the bioactive compounds present in S. wightii, with a specific focus on its polyphenolic content. Additionally, the study seeks to evaluate the antioxidant properties of the compound. By doing so, the research aims to contribute to the growing body of knowledge on marine bioresources and their potential health benefits. Methods S. wightii samples were collected from the Mandapam coastal region in Rameshwaram, India. The cleaned seaweed was transported to the laboratory, where it was further washed, shade-dried, and ground into a fine powder. The powdered seaweed was then subjected to extraction using four different solvents: n-hexane, dichloromethane, ethyl acetate, and methanol. Phytochemical analyses were conducted on these extracts to identify the presence of various bioactive compounds. The total phenolic content of the extracts was determined, and antioxidant activity was assessed using the phosphomolybdenum method. Functional groups present in the extracts were identified using Fourier Transform Infrared (FT-IR) spectroscopy. Results Among the solvents used, the methanol extract yielded the highest amount of crude extract. Phytochemical analysis revealed a variety of bioactive compounds, with the methanol extract showing a notable presence of polyphenols. The total phenolic content was measured at 1.25 ± 0.6 mg gallic acid equivalence (GAE)/g of extract. The antioxidant activity, assessed through the phosphomolybdenum method, demonstrated significant free radical scavenging capabilities with an IC50 (half maximal inhibitory concentration) value of 68.23 ± 3.5 μg/mL. FT-IR spectroscopy confirmed the presence of functional groups characteristic of polyphenols and other bioactive compounds. Conclusion The study highlights the significant potential of S. wightii as a source of bioactive compounds with substantial antioxidant properties. These findings emphasize the importance of marine algae in the development of pharmaceutical and nutraceutical products, showcasing S. wightii's promising role in health-related applications.

Corrosion Behavior and Mechanical Properties of 30CrMnSiA High-Strength Steel under an Indoor Accelerated Harsh Marine Atmospheric Environment

In this work, the corrosion behavior and mechanical properties of 30CrMnSiA high-strength steel under a harsh marine atmosphere environment were systematically studied using accelerated test technology, along with corrosion kinetic analysis, microstructure and phase composition analysis, electrochemical measurements, and mechanical property tests. The influence of corrosion time on corrosion kinetics was characterized by the weight loss method. The corrosion layer and its product evolution were analyzed by SEM, EDS, XRD, and XPS. The corrosion behavior of steel was studied by a potentiodynamic polarization curve and EIS. Finally, the influence of corrosion on mechanical properties was studied by tensile and fatigue tests. The results show that 30CrMnSiA high strength steel has good corrosion resistance in a harsh marine atmosphere environment. Its corrosion behavior is cyclical: the outer rust layer exfoliated, the inner rust layer became the outer rust layer, and the matrix became inner rust due to the attack by the corrosive medium. The rust layer had a great protective effect on the matrix. The mechanical properties of 30CrMnSiA high-strength steel were reduced under the corrosive environment, and corrosion had a significant effect on its fatigue resistance.

Quantitative Understanding of the Environmental Effect on B10 Copper Alloy Corrosion in Seawater

Corrosion in natural seawater is difficult to simulate in a laboratory due to the slow rate and complexity of the corrosion process which involves multiple influential factors. This paper aims to explore the quantitative effect of environmental factors on corrosion process and find the best experimental conditions which represent the actual environment and have the best acceleration effect. A new framework is followed in this paper which consists of three parts: design of experiments, outdoor and laboratory corrosion tests, and corrosion mechanism consistency confirmation. A L6(31 × 22) orthogonal experiment is designed in laboratory to study the effect of temperature, salinity, and dissolved oxygen on marine corrosion behavior of B10 copper alloy. In each test, H2O2 is added in seawater to accelerate the corrosion process. Outdoor exposure tests are also conducted in natural seawater. Results show that the corrosion process in laboratory and outdoor follows the same mechanism, in view of corrosion product and morphology, corrosion kinetics, as well as mechanical properties. With the help of quantitative analysis of the test results, a better acceleration condition can be designed.

Phytochemical screening and anti-oxidant activity of Sargassum wightii enhances the anti-bacterial activity against Pseudomonas aeruginosa

In this study, the phytochemical, phenolic, flavonoid and bioactive compounds were successfully screened from crude extract of Sargassum wightii by LC-MS analysis after NIST interpretation. Bacterial growth inhibition study result was shown with 24 mm zone inhibition at 200 µg/mL concentration against P. aeruginosa. The increased phenolic content was much closed to gallic acid and the range was observed at 250 μg/mL concentration. In addition, flavonoid contents of the algae extract was indicated more significant with rutin at 200 μg/mL. In result, both the phenolic and flavonoid contents of the extract were more correlated with gallic acid and rutin. Further, the total anti-oxidant and DPPH radical scavenging activities were shown increased activity at 200 μg/mL concentrations. Furthermore, the excellent anti-bacterial alteration result was observed at 200 μg/mL concentration by minimum inhibition concentration. Therefore, the result was revealed that the marine algae Sargassum wightii has excellent phytochemical and anti-oxidant activities, and it has improved anti-bacterial activity against P. aeruginosa.