An efficient green ionic liquid for the corrosion inhibition of reinforcement steel in neutral and alkaline highly saline simulated concrete pore solutions

The effect of the green ionic liquid compound, Quaternium-32 (Q-32), on the corrosion inhibition performance of reinforcement steel, in a simulated concrete pore solution, was investigated at different temperatures and pH values, using electrochemical impedance spectroscopy (EIS). The inhibition efficiency was improved as the concentration of Q-32 and pH values were increased. However, it decreased as the temperature was raised. A Q-32 concentration of 20 µmol L–1 exhibited a 94% inhibition efficiency at 20 °C. The adsorption isotherm was evaluated using EIS measurements, and it was found to obey the Langmuir isotherm. The surface topography was examined using an atomic force microscope and scanning electron microscope. The effect of the Q-32 concentration with the highest corrosion efficiency on the mechanical properties of the mortars was also explained by flexure and compression techniques.The authors express their gratitude to the Center for Advanced Materials at Qatar University for technical support. Additionally, the authors are grateful to Qatar University for funding this work through the QUCG-CAM-20/21-2 Grant. The publication of this article was funded by the Qatar National Library

NAFLD and nutraceuticals: a review of completed phase III and IV clinical trials

BackgroundNonalcoholic Fatty Liver Disease (NAFLD) has become a significant public health concern, affecting approximately one-fourth of the population. Despite its prevalence, no FDA-approved drug treatments specifically target NAFLD.AimTo provide a review of clinical trials investigating the use of herbal remedies and dietary supplements in NAFLD management, utilizing the ClinicalTrials.gov database.MethodsThis review evaluates the current evidence by examining completed phase III and IV clinical trials registered on ClinicalTrials.gov. An exhaustive search was performed on April 17, 2023, using the terms “Nonalcoholic Fatty Liver Disease” and “NAFLD.” Two independent reviewers appraised eligible trials based on pre-defined inclusion and exclusion criteria.ResultsAn initial search yielded 1,226 clinical trials, with 12 meeting the inclusion criteria after filtration. The majority of trials focused on Omega-3 fatty acids (20.0%) and vitamin D (26.7%), followed by caffeine, chlorogenic acid, ginger, phosphatidylcholine, Trigonella Foenum-graecum seed extract, vitamin C, and vitamin E (each 6.7%). Most studies were Phase 3 (75.0%) and used a parallel assignment model (91.7%). Quadruple masking was the most prevalent technique (58.3%), and Iran was the leading country in terms of trial locations (25.0%). These interventions constitute two herbal interventions and nine supplement interventions.ConclusionThis reveals a diverse range of nutraceuticals, with Omega-3 fatty acids and vitamin D being predominant in the management of NAFLD. The global distribution of trials highlights the widespread interest in these therapeutics. However, more rigorous, large-scale trials are needed to establish safety, efficacy, and optimal dosages

DPSM technique for ultrasonic field modelling near fluid–solid interface

Distributed point source method (DPSM) is gradually gaining popularity in the field of non-destructive evaluation (NDE). DPSM is a semi-analytical technique that can be used to calculate the ultrasonic fields produced by transducers of finite dimension placed in homogeneous or non-homogeneous media. This technique has been already used to model ultrasonic fields in homogeneous and multi-layered fluid structures. In this paper the method is extended to model the ultrasonic fields generated in both fluid and solid media near a fluid–solid interface when the transducer is placed in the fluid half-space near the interface. Most results in this paper are generated by the newly developed DPSM technique that requires matrix inversion. This technique is identified as the matrix inversion based DPSM technique. Some of these results are compared with the results produced by the Rayleigh–Sommerfield integral based DPSM technique. Theory behind both matrix inversion based and Rayleigh–Sommerfield integral based DPSM techniques is presented in this paper. The matrix inversion based DPSM technique is found to be very efficient for computing the ultrasonic field in non-homogeneous materials. One objective of this study is to model ultrasonic fields in both solids and fluids generated by the leaky Rayleigh wave when finite size transducers are inclined at Rayleigh critical angles. This phenomenon has been correctly modelled by the technique. It should be mentioned here that techniques based on paraxial assumptions fail to model the critical reflection phenomenon. Other advantages of the DPSM technique compared to the currently available techniques for transducer radiation modelling are discussed in the paper under Introduction

Electrochemical behavior of mild and corrosion resistant concrete reinforcing steels

An experimental study is carried out in this paper to evaluate the corrosion performance of mild steel reinforcing bars (MS), high strength steel reinforcing bars (HS), epoxy-coated steel reinforcing bars (EC), and high-chromium steel reinforcing bars (HC) under harsh environmental conditions. Reinforcing bars (rebar) of 16 mm diameter and 310 mm length were embedded in cylindrical concrete samples of 60 mm diameter and 350 mm length, and subjected to a Southern Exposure test for sixteen months. The open circuit potential (OCP) was monitored during the exposure period until corrosion initiation. The linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), and Tafel plot techniques were employed to assess the corrosion rates on the rebar surfaces. The macrocell corrosion current was monitored by connecting the corroding rebar with an external stainless steel bar of the same size. The polarization resistance of the HC was found to be 1.5 times higher than that of the MS. The EIS technique showed that EC, even with damaged epoxy coating, has the highest resistance to chloride attack. The macrocell current of HC rebar was 48% less than that of MS during the active corrosion state. The LPR, EIS and Tafel plots analysis provided the current densities, which were close to each other; indicating the validity of these techniques to study the problem at hand. The corrosion rates from electrochemical methods were compared against the ones calculated by gravimetric methods. The quantitative results from this research may be used in service life prediction of concrete structures with different types of rebar. Extensive analysis of the results indicates that the corrosion resistance of the evaluated steels was in the following decreasing order: EC, HC, MS, and HS.The funding for this research was provided by the National Priorities Research Program of the Qatar National Research Fund (a member of the Qatar Foundation) under the award no. NPRP 7-410-2-169. The statements made herein are solely the responsibility of the authors and do not necessarily reflect the opinions of the Sponsor. Authors are also thankful to the Qatar Steel Company, Qatar Metals Coating Company, Mesaieed, Qatar, for providing the materials.Scopu

Enhancing the corrosion resistance of reinforcing steel under aggressive operational conditions using behentrimonium chloride

Aggressive operational conditions e.g. saline media and acidic gases, e.g., CO2 can increase the corrosion rate of reinforcing steel. Accordingly, the necessity to protect the steel under the above conditions without affecting the mechanical properties of the concrete is growing. Herein, the inhibition efficiency of a new corrosion inhibitor, behentrimonium chloride (BTC, C25H54ClN), is explored in a simulated-concrete pore solution (SCP) with 3.5 wt.% NaCl at different pH using electrochemical impedance spectroscopy (EIS) and polarization methods. Using only a 50 μmol L−1 of BTC, we are able to measure an inhibition efficiency of 91, 79, and 71% in SCP solution with 3.5% NaCl at pH of 12.5, 10 and 7, respectively without showing any effect on the mechanical properties on the cured mortars. Temkin isotherm is used to describe the physisorption of BTC inhibitor on the steel surface. Also, the adsorption and influence of the inhibitor on the metal surface are characterized using the scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. In conclusion, this new inhibitor shows high corrosion inhibition efficiencies under different aggressive conditions and can be used in concrete to reduce the corrosion rate of reinforcing steel without decreasing the mechanical properties of the concrete.Other Information Published in: Scientific Reports License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1038/s41598-019-54669-y</p