Galvanostatic optimization of polyaniline coating on mild steel in tartrate medium for corrosion protection

82-87Optimization of polyaniline (PANI) coating on mild steel (MS) surface has been studied in 0.3 M aniline + 0.2 M sodium potassium tartrate (Na-K Tartrate) by galvanostatic polarization. The current densities of 0.5, 0.75. 1 and 2 mA cm-2 are used for the electrodeposition of PANI on MS. The obtained PANI coatings have been characterized for its morphology using an optical microscope and corrosion performance by using potentiodynamic polarization in 0.4 M Na2SO3 solution simulating an industrial environment. The results reveal a sequential process of dissolution of MS, passivation of MS by forming tartrate salt followed by oxidation of aniline monomer and subsequential nucleation and growth of PANI coating. It is found that the PANI coating obtained at 0.5 mA cm-2 results in better coating producing corrosion inhibition efficiency (IE) of approximately 90% compared to IE of about 75% for coating obtained at 2 mA cm-2

Bark Extract of Lantana camara in 1M HCl as Green Corrosion Inhibitor for Mild Steel

Lantana camara, an invasive species that adversely affects habitant, bioregions and environment has been studied as corrosion inhibitor. Methanolic extract of barks of Lantana camara in 1 M hydrochloric acid was tested as corrosion inhibitor on mild steel using potentiodynamic polarization technique. The corrosion inhibition efficiency of extract varied with concentration of extract and immersion of time. The inhibition was found to increase with increase in concentration of the extract. The polarization behavior of mild steel revealed that maximum inhibition efficiency is 97.33 % and 89.93 % respectively in the 1000 and 200 ppm concentration of the inhibitor respectively. The results showed that the extract of the barks of Lantana camara served as a mixed type inhibitor

Gut Microbiota, Probiotics and Diabetes

Diabetes is a condition of multifactorial origin, involving several molecular mechanisms related to the intestinal microbiota for its development. In type 2 diabetes, receptor activation and recognition by microorganisms from the intestinal lumen may trigger inflammatory responses, inducing the phosphorylation of serine residues in insulin receptor substrate-1, reducing insulin sensitivity. In type 1 diabetes, the lowered expression of adhesion proteins within the intestinal epithelium favours a greater immune response that may result in destruction of pancreatic β cells by CD8+ T-lymphocytes, and increased expression of interleukin-17, related to autoimmunity. Research in animal models and humans has hypothesized whether the administration of probiotics may improve the prognosis of diabetes through modulation of gut microbiota. We have shown in this review that a large body of evidence suggests probiotics reduce the inflammatory response and oxidative stress, as well as increase the expression of adhesion proteins within the intestinal epithelium, reducing intestinal permeability. Such effects increase insulin sensitivity and reduce autoimmune response. However, further investigations are required to clarify whether the administration of probiotics can be efficiently used for the prevention and management of diabetes

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Electrochemical Impedance Response of Zn and Galvanized Steel Corroding under Marine Atmospheric Environments

Impedance response of zinc and galvanized steel samples exposed in wet-dry cyclic condition using 0.05 M NaCl solution has been analyzed in order to evaluate their corrosion behavior. The wet-dry cyclic test was performed by exposing sample to alternate conditions of 1 h immersion in 0.05 M NaCl solution and 7 h drying at 298 K with relative humidity (RH) of 60 % for 10 days consisting of 30 cycles. After initial exposure to corrosion test, samples showed the evolution of two capacitive loops. However, a sharp decrease of characteristic frequency, characterized by an increase of double layer capacitance in the rage of several mF/cm 2, with the progress of corrosion was observed. This was explained by taking into account the coupling of characteristic frequencies of the two capacitive loops due to deposition of thick layer of porous rust. The parameters of diffusion impedance for the cathodic process were estimated from the low frequency capacitive loops attributed to finite Warburg diffusion impedance. A sharp increase of impedance after several days of corrosion in the case of galvanized steel was attributed to the dissolution of Fe-Zn alloy layer that is formed during galvanizing process

Comparative Study of Corrosion Inhibition Efficacy of Alkaloid Extract of <i>Artemesia vulgaris</i> and <i>Solanum tuberosum</i> in Mild Steel Samples in 1 M Sulphuric Acid

Two different types of alkaloids are successfully extracted from two plants Artemisia vulgaris (AV) and Solanum tuberosum (ST) in the laboratory and used as corrosion inhibitors for mild steel samples. The corrosion inhibition potential of these alkaloids is determined by weight loss and potentiodynamic polarization measurement methods. Based on the weight loss measurement study of a sample immersed for 6 h in 1000 ppm inhibitor solution of AV and ST alkaloids, the corrosion inhibition efficiency is found to be 92.58% and 90.79%, respectively. The potentiodynamic polarization measurement shows 88.06% and 83.22% corrosion inhibition efficiency for AV and ST alkaloids, respectively, for the sample immersed for 1 h in 1000 ppm inhibitor solution. These promising efficiency and suitable immersion time effect can lead to the development of good green inhibitors

Comparative Study of Corrosion Inhibition Efficacy of Alkaloid Extract of Artemesia vulgaris and Solanum tuberosum in Mild Steel Samples in 1 M Sulphuric Acid

Two different types of alkaloids are successfully extracted from two plants Artemisia vulgaris (AV) and Solanum tuberosum (ST) in the laboratory and used as corrosion inhibitors for mild steel samples. The corrosion inhibition potential of these alkaloids is determined by weight loss and potentiodynamic polarization measurement methods. Based on the weight loss measurement study of a sample immersed for 6 h in 1000 ppm inhibitor solution of AV and ST alkaloids, the corrosion inhibition efficiency is found to be 92.58% and 90.79%, respectively. The potentiodynamic polarization measurement shows 88.06% and 83.22% corrosion inhibition efficiency for AV and ST alkaloids, respectively, for the sample immersed for 1 h in 1000 ppm inhibitor solution. These promising efficiency and suitable immersion time effect can lead to the development of good green inhibitors

Preparation of an Amperometric Glucose Biosensor on Polyaniline-Coated Graphite

Control of glucose concentration has tremendous significance in medical diagnosis, pharmaceuticals, food, and fermentation industries. Herein, we report on the fabrication of a facile, low-cost, and sensitive enzyme-based amperometric sensor using the electrochemically deposited polyaniline (PANI) film on a graphite electrode. PANI was deposited from an aqueous solution of 0.2 M aniline in 1.0 M hydrocholoric acid (HCl) by cyclic voltammetry (CV). Surface morphology and composition characterization of the PANI film were carried out by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared (FTIR) spectroscopy. Potentiostatic immobilization of glucose oxidase (GOX) enzyme in the PANI film was carried out at 0.75 V to fabricate an amperometric glucose biosensor (GOx/PANI/graphite biosensor). The glucose concentration response of the prepared sensor was studied amperometrically by detecting hydrogen peroxide (H2O2). The detection of H2O2 was optimized by calibrating the effects of pH, reduction potential, and background current. A reduction potential of -0.4 V at pH 6 was the best combination to get a maximum amperometric response of the GOx/PANI/graphite biosensor. A stable current response was obtained in 4 min with a high reproducibility in linearity within the concentration range of 0.01 M-0.1 M D-glucose. Therefore, the fabricated GOx/PANI/graphite biosensor could be a promising candidate for glucose sensing

Alkaloid of <i>Rhynchostylis retusa</i> as Green Inhibitor for Mild Steel Corrosion in 1 M H₂SO₄ Solution

Alkaloids are aromatic hydrocarbons with nitrogen as heteroelements in the ring structure that are responsible for bonding with the metal surface and help to reduce corrosion of metals such as mild steel (MS) in an acidic medium. In this study, the alkaloid of Rhynchostylis retusa (RR) was extracted by solvent extraction method and confirmed by chemical test as well as FTIR spectroscopic test. Extracted alkaloids were tested as green inhibitors for the MS corrosion in a 1.0 M H2SO4 solution. The inhibition efficiency (IE) of alkaloid extracts of RR was studied by the weight loss measurement method and electrochemical polarization method. Results showed that the maximum IE in the gravimetric method was 87.51% in 1000 ppm solution at 6 h immersion time. Open circuit potential (OCP) and potentiodynamic polarization results indicated that the extracted alkaloids acted as a mixed type of inhibitor. IE by polarization method was found to be 93.24% for the sample immersed for 6 h. The temperature effect study reveals that inhibitors can work only below 35 °C. Alkaloids of RR can be successfully extracted and used as corrosion inhibitors for MS in an acidic medium below 35 °C