Search Results (401)

Although not expected to be used due to restrictions raised on their usage, Persisted Organic Pollutants (POP) such as organochlorinated pesticides (OCPs) can be found in several matrices, even nowadays. The lack of biodegradation and, furthermore, their persistence in the environment result in the possible occurrence of these lipophilic toxins in several matrices, from environmental samples and foods to human milk. The current review focuses on the usage of hyphenated techniques for the determination and monitoring of OCPs in several matrices, such as milk—both animal and human milk. The lipid matrix of milk and dairy products favors the possible bioaccumulation of the above pollutants, and the complex matrix of the dairy products is a challenge for method development. Additionally, spectroscopic methods—mainly Nuclear Magnetic Resonance (NMR)-based metabolomics—for biomonitoring of OCPs persistence, bioaccumulation, and effect of possible exposure, along with NMR usage in several methods developed, are also presented and discussed. Finally, we introduce and present the metabolomic approach for OCPs and other POPs in lipid matrices. Full article

Aiming at the problem of multiple constraints and low solving efficiency in the process of vehicle path tracking, an improved hp-adaptive Radau pseudospectral method (I-hp-ARPM) which uses a double-layer optimization iteration strategy and the residual of differential algebraic constraints at sampling points with a Gaussian distribution as the error evaluation criterion is proposed. Firstly, a four-DOF vehicle motion model is established. Secondly, on the basis of establishing algebraic differential constraints and path constraints and satisfying the optimization objective function, the I-hp-ARPM is used to transform the optimal control problem (OCP) into a general nonlinear programming problem for solution. Finally, the effectiveness of the proposed method is verified compared with the traditional hp-adaptive pseudospectral method. The simulation results and the virtual test show that there are peak values at 3.5 s and 4.8 s, as well as 6 s, for both the steering wheel angle and the sideslip angle with the condition of $\mu$ = 0.8. And also, there are peak values at the times of 3.5 s and 5.5 s, as well as 7.5 s, with the condition of $\mu$ = 0.4. This indicates the vehicle can track the reference path well with the control of the proposed algorithm. Both the initial and final constraints, as well as the path constraint, meet the requirements. The proposed method can generate the optimal trajectory that meets various constraint requirements. This method provides a design basis for path tracking of autonomous vehicles and has significance in engineering. Full article

Electroless ZnO (≈900 nm) was deposited on the surface of an Mg-Al alloy (AM60) to reduce its degradation in the marine environment. Uncoated and coated ZnO samples were exposed to an SME simulated marine solution for up to 30 days. The AFM and optical images revealed that the corrosion attack on the ZnO-AM60 surface was reduced due to an increase in the surface hydrophobicity of the ZnO coating (contact angle of ≈91.6°). The change in pH to more alkaline values over time was less pronounced for ZnO-AM60 (by ≈13%), whereas the release of ${\mathrm{Mg}}^{2+}$ ions was reduced by 34 times, attributed to the decrease in active sites on the Mg-matrix provided by the electroless ZnO coating. The OCP (free corrosion potential) of ZnO-AM60 shifted towards less negative values of ≈100 mV, indicating that electroless ZnO may serve as a good barrier for AM60 in a marine environment. The calculated polarization resistance (${\mathrm{R}}_{\mathrm{p}}$), based on EIS data, was ≈3 times greater for ZnO-AM60 than that of the uncoated substrate. Full article

Abradable seal coatings represent a critical technology within the realm of advanced power systems, designed to minimize airflow channel leakage, thereby reducing energy consumption and enhancing overall efficiency. In the present study, CuAl/BN, CuAlLaF₃/BN, and CuAlY/BN abradable seal coatings were prepared using plasma spraying technology. Both the as-deposited coatings and high-temperature oxidation-treated coatings were comprehensively investigated by means of scanning electron microscopy (SEM), open-circuit potentials (OCP), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), salt-spray corrosion testing, and bond strength evaluations. The results show that the addition of rare earth elements to the CuAl/BN coatings does not enhance the corrosion resistance of the coatings and even leads to a decrease in the corrosion resistance of the coatings. In contrast, the CuAlY/BN coatings exhibited a significant improvement in corrosion resistance following an oxidation treatment at 550 °C. This enhancement is attributed to the yttrium (Y) element, which facilitates the formation of passivation films and confers a resistance effect, thereby bolstering the coatings’ resistance to corrosion. The bond strength of the high-temperature oxidation-treated CuAlY/BN coating was improved by about 30% after 960 h of salt-spray corrosion. Full article

The objective of this research work is the study of the inhibitory effect of Warionia saharea essential oil (WSEO) on the corrosion of mild steel (MS) in molar HCl solution, employing both experimental and theoretical methods. This inhibitory effect (IE) has been evaluated by using a combination of weight loss measurements (LW) and various electrochemical methods, such as open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) experiments. The LW results indicated that IE increased with inhibitor concentration, reaching 83.34% at 3.00 g/L. The PDP analysis suggested that WSEO functions as a mixed inhibitor, while in the EIS results the R_ct values increased with inhibitor concentration to reach 165.8 Ω cm² at 2.00 g/L, suggesting a defensive film formation by WSEO molecules over the metallic surface. The thermodynamic study demonstrated that the WSEO molecules adsorption on the MS surface followed a Langmuir isotherm, involving mixed physical and chemical (physicochemical) adsorption on the MS surface. Theoretical methods, including density functional theory (DFT) and molecular dynamics (MD) simulations, were employed to elucidate the inhibition mechanisms of the three main components of WSEO. The quantum chemical analysis, using density functional theory (DFT) and molecular dynamics (MD) simulations, showed a low ΔE_gap value of 6.30 eV and a low adsorption energy (E_ads) value on an Fe (110) substrate of −258 Kcal/mol for (E)-Nerolidol, indicating the significant contribution of this molecule to the overall corrosion inhibition effect of WSEO. The scanning electron microscope (SEM) analysis verified the presence of a protective film formed by the inhibitor on the MS surface. This study highlights the potential of WSEO as a sustainable and green corrosion inhibitor in acidic environments. Full article

As the world transitions towards a more sustainable future, it is imperative to develop innovative solutions that address the pressing issue of plastic pollution. Microplastics, in particular, have become a significant concern due to their widespread presence in the environment and potential to interact with toxic pollutants. Organic compounds, which include a variety of harmful chemicals, such as pesticides and other industrial chemicals, are often released into the environment and can readily bind to microplastics. In this context, understanding the adsorption of organic compounds on microplastics is crucial for designing effective strategies to mitigate their environmental impacts. This study investigates the adsorption dynamics of organochlorine pesticides (OCPs) on polystyrene microplastics, exploring the influence of pH and contact time, as well as utilizing kinetic models and isothermal equations to elucidate the adsorption mechanism. The results suggest that the pH level has a negligible impact on the adsorption capacity of PS for OCPs. In contrast, the contact time plays a significant role in the amount of OCPs adsorbed onto the PS surface. Interestingly, a relatively short time of up to 6 h was sufficient to reach equilibrium. The adsorption of OCPs on PS follows a uniform pattern consistent with the Freundlich isotherm model, indicating a multilayer adsorption process. The use of kinetic models to describe the adsorption process was also found to be useful in understanding its mechanism. Specifically, the pseudo-second-order kinetic model proved to be a suitable descriptor for the adsorption process of organochlorine pesticides on PS. This study highlights the importance of understanding the interactions between microplastics and organic pollutants, which is crucial for developing sustainable solutions to mitigate the environmental impacts of plastic pollution, ultimately contributing to a more environmentally conscious future. Full article

In this work, heat treatment of three different temperatures (600 °C, 800 °C, and 1000 °C) was applied to as-cast Al_0.75CoCr_1.25FeNi high-entropy alloys (HEAs) to investigate the influence of heat treatment on their corrosion properties. Open circuit potential (OCP) and cyclic polarization tests reveal that the 1000 °C heat-treated HEA possesses excellent corrosion resistance, as indicated by the low corrosion tendency and corrosion current density. Electrochemical impedance spectroscopy (EIS) and potentiostatic polarization analyses imply the presence of a superior passive film on the 1000 °C heat-treated HEA. X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the passive film formed on the 1000 °C heat-treated HEA during potentiostatic polarization tests is most corrosion-resistant since it possesses the highest ratio of Al₂O₃/Al(OH)₃ and Cr₂O₃/Cr(OH)₃. Full article

Machine learning has gained significant recognition as a powerful approach for medical diagnosis using medical images. Among various medical imaging modalities, contrast-enhanced CT (CECT) is utilized to obtain additional diagnostic information that improves visualization and evaluation of certain abnormalities in the human body, as well as to observe temporal changes in lesions and tumors across different time phases. However, developing such medical diagnostic systems presents two significant challenges: high technical complexity and substantial development effort. This paper presents a software platform that effectively addresses these challenges. Specifically, we propose a unified software process that fully automates contrast-enhanced CT (CECT)-specific disease diagnosis, with key tasks performed by leveraging task-specific machine learning models to enhance accuracy. The platform incorporates a suite of specialized machine learning models into the diagnostic process, enabling precise diagnosis of lesions, malignancies, tumors, tumor characteristics, and temporal changes over phases. Moreover, the platform has been designed according to the Open–Closed Principle, allowing it to be applicable to a wide range of CECT-based diagnostic systems. The platform has been implemented in Python using the Scikit-learn and TensorFlow libraries. To validate its applicability and reusability, a hepatocellular carcinoma (HCC) diagnosis system has been implemented. Full article

The presence of anthropogenic compounds, including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), was studied in three salt marshes within the Tagus estuary, Portugal, along an anthropogenic pressure gradient. Results revealed differences in OCPs and PCBs among the marshes, with differing concentration levels. Specifically, one marsh, with surrounding agricultural activity, showed the highest OCP concentrations, while another, with a historical industrial past, exhibited elevated PCB levels. In contrast, a third marsh, part of a natural reserve, displayed comparatively lower concentrations of both substances. Sediment concentrations, likely influenced by agricultural practices, were found to be comparable to or higher than those observed in other Portuguese estuaries. The halophyte Spartina maritima was found to absorb OCPs, particularly in its aboveground tissues, suggesting bioaccumulation within the plant. Additionally, PCB levels appeared to be influenced by industrial history, with one marsh displaying notably higher concentrations. In conclusion, the persistence of organochlorine compounds in the salt marsh ecosystems notwithstanding the regulatory prohibitions implemented in the 1990s highlights the need for continuous monitoring and study of such sites and the necessity of remediation practices, which are imperative to mitigate ecological and health risks in these polluted salt marshes. Full article

Two-month experiments were carried out with carbon steel electrodes buried in an artificial sand wetted at 50–55% of saturation with a 0.07 mol L⁻¹ Na₂SO₄·10H₂O solution. Various protection potentials (corrected from the ohmic drop) were applied from −0.60 to −1.13 V/Cu-CuSO₄. In each case, the behavior of the electrode protected by cathodic polarization was compared with that of an unprotected electrode. The electrochemical study was performed using voltammetry, linear polarization resistance measurements, and EIS. Surface characterization of the coupons was carried out using optical microscopy and X-ray diffraction. First, cathodic protection was observed to induce a spreading of the electrolyte on the metal surface because of electrocapillary effects. The active area, or more precisely the wet area, of the electrode increased, leading to a decrease in soil electrolyte resistance R_s measured using EIS. This phenomenon was experimentally confirmed via visual observations of the surface of the coupons at the end of the experiments. Secondly, cathodic protection induced a passivation of the steel surface. The passive state persisted for 35 to 85 h after cathodic protection was stopped and could be studied during various periods of interruption of the protection. In each case, the OCP of the previously polarized coupons reached high values, actually 200–250 mV higher than those measured for the unprotected coupons, and was associated with high polarization resistance R_p values (~40 kΩ cm²). Depassivation of the metal finally occurred, a phenomenon revealed by simultaneous important drops of both OCP and R_p. Full article

The temperature response of pavement is not only crucial for assessing the internal stresses within pavement structures but is also an essential parameter in pavement design. Investigating the temperature response of rubberized concrete pavements (RCP) can support the construction of large-scale rubber concrete pavements. This study constructed a pavement monitoring system based on fiber Bragg grating technology to investigate the temperature distribution, temperature strain, temperature effects, and temperature stress of RCP. The results show that the daily temperature–time history curves of concrete pavement exhibit a significant asymmetry, with the heating phase accounting for only one-third of the curve. The temperature at the middle of RCP is 1.8 °C higher than that of ordinary concrete pavement (OCP). The temperature distribution along the thickness of the pavement follows a “spindle-shaped” pattern, with higher temperatures in the center and lower temperatures at the ends. Additionally, the addition of rubber aggregates increases the temperature strain in the pavements, makes the temperature–strain hysteresis effect more pronounced, and increases the curvature of the pavement slab. However, the daily stress range at the bottom of RCP is approximately 0.7 times that of OCP. Full article

Bone grafting is crucial for bone regeneration. Recent studies have proposed the use of calcium citrate (CC) as a potential graft material. Notably, citrate does not inhibit hydroxyapatite (HAp) formation at specific calcium-to-citrate molar ratios. Octacalcium phosphate (OCP)/gelatine (Gel) composites, which are commonly produced from porcine Gel, are valued for their biodegradability and bone replacement capability. This study introduces fish Gel as an alternative to porcine Gel because of its wide acceptance and eco-friendliness. This is the first study to examine the interaction effects between two osteogenic materials, OCP/CC, and the influence of different gelatine matrix components on HAp formation in an SBF. Samples with varying CC contents were immersed in an SBF for 7 d and analysed using various techniques, confirming that high CC doses prevent HAp formation, whereas lower doses facilitate it. Notably, small-sized OCP/CC/porcine Gel composites exhibit a high HAp generation rate. Porcine Gel composites form denser HAp clusters, whereas fish Gel composites form larger spherical HAps. This suggests that lower CC doses not only avoid inhibiting HAp formation but also enhance it with the OCP/Gel composite. Compared with porcine Gel, fish Gel composites show less nucleation but an increased crystal growth for HAp. Full article

Lithium-ion batteries are superior energy storage devices that are widely utilized in various fields, from electric cars to small portable electric devices. However, their susceptibility to thermal runaway necessitates improvements in battery case materials to improve their safety. This study used electrochemical analyses, including open-circuit potential (OCP), potentiodynamic polarization, and critical pitting temperature (CPT) analyses, to investigate the corrosion resistance of super duplex stainless steel (SAF 2507) applied to battery cases in relation to post-weld heat treatment (PWHT) time. The microstructure during the manufacture, laser welding, and PWHT was analyzed using field-emission scanning electron microscopy, X-ray diffraction, and electron backscatter diffraction, and the chemical composition was analyzed using dispersive X-ray spectroscopy and electron probe micro-analysis. The PWHT increased the volume fraction of austenite from 5% to 50% over 3 min at 1200 °C; this increased the OCP from −0.21 V to +0.03 V, and increased the CPT from 56 °C to 73 °C. The PWHT effectively improved the corrosion resistance, laying the groundwork for utilizing SAF 2507 in battery case materials. But the alloy segregation and heterogeneous grain morphology after PWHT needs improvement. Full article

In order to improve fuel economy to meet the standard for passenger car oil, a new formulation with good viscosity–temperature performance for gasoline engine oil is required. In this study, coal-to-liquid (CTL) base oil, with a high viscosity index and good low-temperature performance, was selected as the base oil to develop the gasoline engine oil. A systematic study on the molecular interaction between the CTL base oil and the viscosity index improver (VII), including three kinds of hydrogenated styrene diene copolymers (HSD-type) and four kinds of ethylene propylene copolymers (OCP-type), was conducted. It was found that in general, in CTL base oil, the HSD-type VII exhibited a much higher viscosity index, a significantly lower shear stability index, a higher thickening ability, and a lower cold-cranking simulator (CCS) viscosity than that of OCP-type VII. Moreover, when comparing CTL base oil with mineral oil 150N, the combination of CTL base oil and the VII displayed a lower CCS viscosity than that of mineral oil, suggesting it had better low-temperature performance and was able to quickly form a protective oil film on the surface, which was beneficial for the cold start. The functional group distribution state of the VII in base oil was analyzed using synchrotron radiation micro-infrared microscope (SR Micro-IR) technology, which revealed that HSD-1 had a better molecular interaction with CTL6 than 150N because of the better uniformity of the C=C group distribution. Based on this, a SP 0W-20 gasoline engine oil was developed by the combination of CTL base oil and the HSD-1 viscosity index improver, together with an additive package, a polymethacrylate pour point depressant, and a non-silicone defoamer, which showed excellent low-temperature performance, thermal oxidation stability, and detergency performance compared to the reference oil. Full article

The objective of this study was to evaluate the coating integrity performance and corrosion protection property of trimethylsilane (TMS) plasma nanocoatings that were directly deposited onto cobalt chromium (CoCr) L605 cardiovascular stents. Hydrophilic surfaces were achieved for the TMS plasma nanocoatings that were deposited onto the coronary stents through NH₃/O₂ (2:1 molar ratio) plasma post-treatment. With a coating thickness of approximately 20–25 nm, the TMS plasma nanocoatings were highly durable and able to resist delamination and cracking from crimping and expansion by a Model CX with a J-Crimp Station. The stent surface that was evaluated by Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) showed no indications of pitting, corrosion, or adsorption products on either the luminal or abluminal surfaces of the stents, in contrast to the uncoated stent surface. The TMS plasma nanocoatings significantly enhanced the stent’s corrosion resistance in immersion experiments that followed the ASTM F2129-15 corrosion protocol, evident in the increase of the open circuit potential (OCP) from 0.01 V for the uncoated L605 stent to 0.18 V for the plasma-nanocoated L605 stent, reducing potential cytotoxic metal ion release. Cyclic polarization (CP) curves show that the corrosion rate (density level) observed in plasma-nanocoated L605 stents was approximately half an order of magnitude lower than that of the uncoated stents, indicating improved corrosion protection of the stents. CP curves of the TMS plasma-nanocoated stents with different coating thicknesses show that, in the range of 20–65 nm, the coating thickness does not result in any difference in the corrosion resistance of the stents. Full article