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In order to study the electromagnetic wave transmission characteristics in seawater under external physical effects, we present a study of seawater ionic solution and perform a theoretical basis of magnetic field on water molecules and ionic motion to investigate the variation of dielectric properties with frequency under static magnetic field (0.38 T). Seawater is a naturally multi-component electrolyte solution, the main ingredients in seawater are inorganic salts, such as NaCl, MgSO₄, MgCl₂, CaCl₂, KCl, NaHCO₃, etc. The dielectric properties of these electrolyte solutions with different salinity values (0.01–5%) were measured in frequencies ranging from 40 to 5 MHz at 12${}^{\circ }$C. The results show that the dielectric constant decreases with increasing frequencies no matter with magnetic field or without it. Frequency dependence of the dielectric constant of NaCl solution increases under magnetic field at measure concentrations. In a solution of MgCl₂ ⋅ 6H₂O, KCl and NaHCO₃ are consistent with NaCl solution, while CaCl₂ ⋅ 2H₂O solution is in contrast with it. We also find that dielectric loss plays a major role in complex permittivity. With the effect of magnetic field, the proportion of dielectric loss is reducing in complex permittivity. On this basis it was concluded that the magnetic field influences the orientation of dipoles and the variation is different in salt aqueous solution.

To determine the optical parameters of crude oil and seawater systems, we carried out spectral investigations using the ellipsometry method, which is a highly sensitive and accurate optical method for studying the surfaces and interfaces of various media. This method is based on studying the change in the polarization state of reflected light after its interaction with the surface of interfaces of these media. Crude oil and seawater from different regions of Caspian Sea were accessed by spectroscopic ellipsometry over the 200–1700 nm spectral range at room-temperature. Optical constants and dielectric function were obtained for massive samples of each substance, as well as for ultrathin layers of the oil spilled over the sea surface. Dielectric function, when completely determined in the frequency regions corresponding to electronic transitions and excitation of atomic or molecular vibrations in the object, is a unique dielectric fingerprint of this object. Oils with even miserable difference in type and concentration of biomarkers and heterocomponents will have different dielectric functions. The possibility to use dielectric function as a unique optical fingerprint for oil identification is figured out.

A method has been proposed to reason the choice among the known optimized models for methods for estimating chlorophyll (Chl) concentration in the seawater according to the information-logarithmic criterion, which provides a comparison of theoretical models by the SeaWiFS data. It has been shown that the most appropriate means is to determine the Chl concentration, since the concentration of Chl in seawater is systematically investigated by marine ships or remote sensing. All optimized models of the optical properties of seawater can be verified by checking the simulated and measured Chl concentration data.

In this work, a sensitive fluorescent sensor for the detection of ciprofloxacin (CIP) was developed by wrapping the surface of CdTe quantum dots (QDs) with molecularly imprinted polymers (MIPs). The MIP@QDs were synthesized via a simple sol–gel method using 3-aminopropyltriethoxysilane (APTES) as the functional monomer and tetraethoxysilane (TEOS) as the crosslinker. The fluorescence emission of the probe was at 643 nm. Linear calibration curves were obtained in the range of 0.5–24 $\mu$M for CIP with the detection limit of 0.23 $\mu$M (S/N$=$3). The fluorescent probe was successfully applied to the determination of CIP in seawater samples with the spiked recoveries ranging from 98.2% to 110.6% and the relative standard deviation (RSD) was less than 10.7%. It is the first time that QDs with molecularly imprinted polymers (MIP@QDs) were introduced for separation and detection of CIP in seawater and obtained good specific identification ability and potential practical value.

In this study, the influences of electrolytic gas generation on the surface of aluminum as a cushioning media against cavitation bubbles were experimentally investigated. The electrolytic gas evolution was controlled by applying electric current to the metal with different polarity and current densities. The surface of the metal specimen was either polarized anodically or cathodically while simultaneously being subject to vibratory cavitation. It was revealed that the surface damage behavior was mainly dependent on the current densities applied to the metal. It was apparent that a moderate current density range of between $-1\times 10^{-3}$ and $-7.5\times 10^{-3}$ A/cm² applied cathodically can produce electrolytic gas evolution to cushion the cavitation bubbles sufficiently. However, application of a too a high current density (greater than $-1\times 10^{-3}$ A/cm${}^2)$ may lead to cathodic corrosion of Al alloys.

This paper aims to provide a method for improving the tribological properties of 316L stainless steels in seawater. During the experimental process, laser texturing technology was used to create biomimetic micro-textures inspired by turtle shell patterns on the 316L stainless steel surfaces. Then, CrAlSiN coating was deposited on the textured surface using the physical vapor deposition (PVD) technique, allowing us to study the frictional properties of the samples in both atmospheric and seawater environments. The results showed that, compared to polished 316L stainless steel, the specimens treated with micro-texture and CrAlSiN coating exhibited a reduction in wear rate by 52.1% and 71.8% under atmospheric and seawater friction conditions, respectively. Under atmospheric friction conditions, the micro-textures had a limited effect on reducing the friction of the 316L stainless steel substrate. However, the CrAlSiN coating, due to its excellent mechanical properties, significantly improved the wear resistance of the 316L stainless steel. Under seawater friction conditions, the continuous CrAlSiN coating played a role in reducing 316L stainless steel wear and seawater corrosion. At the same time, the micro-textures acted as reservoirs for wear debris and seawater, forming a more stable seawater lubricating film and reducing the friction coefficient. Therefore, the synergistic effect of the CrAlSiN coating and biomimetic micro-textures demonstrated remarkable improvement in the tribological performance of 316L stainless steel in seawater environments.