SAM JOHN
@sbcollege.ac.in
ASSISTANT PROFESSOR , DEPARTMENT OF CHEMISTRY
UNIVERSITY OF CALICUT.st berchmans college kerala, INDIA
Scopus Publications
Scopus Publications
Sam John, Zachariah Pulluparampil Mathew, Cyril Augustine, James Baben George, Bincy Joseph, and M.K. Sarath Josh
Elsevier BV
K. P. Greeshma, R. Thamizselvi, S. Muthulingam, Sam John, and Dhanya B. Sen
Informatics Publishing Limited
Nowadays, most antiviral drugs are plant-based due to their low toxicity and high resistance. Morinda citrifolia (Noni) is such a perennial shrub a popular plant based medicine due to its wide therapeutic applications. The phytochemicals present in its fruit as well as its leaf have many antiviral properties and can enhance the human immune system. Herein, we report the identification of bioactive components present in the Morinda citrifolia (Noni) ethanolic leaf extract by GC-MS analysis and their biological interaction with human parallel-stranded 7-mer g-quadruplex DNA of MCF-7 using Biovia Discovery Studio software. In vitro analysis by MTT assay of the same extract reported a living cells of 59.74% at 100 µg/ml. The GC-MS analysis of ethanolic leaf extract revealed the presence of 27 bioactive components, and out of these, six major components were interacted with cancer DNA. The molecular docking interaction identified the most active bio component Phytol, with a binding energy of -27.0796 Kcal/mol. this value is much better than the commercially available doxorubicin. This novel study will provide insight into the development of bioactive components from Morinda citrifolia leaf extract against human breast cancer with minimal side effects.
Sreelakshmi Rajeevan, Sam John, Deepalekshmi Ponnamma, and Soney C. George
Elsevier BV
G. K. Shamnamol, Sam John, and Jaya Mary Jacob
Springer Science and Business Media LLC
Zachariah Pulluparampil Mathew, G.K. Shamnamol, K.P. Greeshma, and Sam John
Elsevier BV
G K Shamnamol, Sam John, and Jaya Mary Jacob
IOP Publishing
Abstract Owing to the high economic and environmental concerns, nowadays scientists have taken much attention to mitigate corrosion. The effectiveness of Garcinia gummi-gutta leaf extract (GGLE) at inhibiting corrosion on mild steel in 1 M HCl was examined in the current study using a weight loss strategy. The GGLE concentration was changed from 100 to 6000 ppm, and the results show that expanding the inhibitor concentration increased the efficacy of corrosion inhibition. At 6000 ppm concentration and 30°C, the maximum inhibitory efficiency was 82.2%; this efficiency decreases as temperature increases. The mechanism of sorption was deliberated by means of different adsorption isotherm and Langmuir adsorption isotherm model holds good for elucidating the adsorption mechanism. The thermodynamic and kinetic parameters were estimated to depict the corrosion process. X-ray photoelectron spectroscopy (XPS) was also used to confirm the development of a coating of inhibitor fragments that protect the metal surface.
Sam John, Sreelakshmi Rajeevan, K.P. Greeshma, and Soney C. George
Elsevier
G.K. Shamnamol, P. Rugma, Sam John, and Jaya Mary Jacob
Elsevier BV
Sreelakshmi Rajeevan, Sam John, Deepalekshmi Ponnamma, and Soney C. George
Elsevier BV
Sajini T, Sam John, and Beena Mathew
Springer Science and Business Media LLC
Shamnamol G.K., Sam John, and Jaya Mary Jacob
Emerald
Purpose Surface pretreatment of iron and its alloys to remove stains and inorganic contaminants on the metal surface undergoes dissolution by virtue of the strong acidic media thereby increasing its susceptibility to corrosion. The purpose of this study is to explore the corrosion mitigation prospects of green corrosion inhibitors on mild steel surface. Design/methodology/approach Corrosion inhibition performance of Garcinia gummi-gutta leaf extract (GGLE) was explored against mild steel in 1 M HCl solution using the weight-loss method, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. Surface characterization was carried out to study the mechanism of inhibitor action. Findings The concentration of GGLE varied from 100 to 6,000 ppm and the result indicates that corrosion inhibition efficiency was amplified by raising the inhibitor concentration. The maximum inhibition efficiency was 82.2% at 6,000 ppm concentration. EIS results show the development of a protective layer of inhibitor molecule over the metal surface and PDP demonstrates that the inhibitor operates as a mixed-type inhibitor. Scanning electron microscopy and atomic force microscopy were executed to assess the surface morphology and roughness, respectively. Originality/value To the best of the authors’ knowledge, so far, no studies have been reported on the corrosion inhibition performance of GGLE which is rich in many bioactive components especially hydroxyl citric acid. This work encompasses the corrosion inhibition capability of GGLE against mild steel in an acidic medium.
Sreelakshmi Rajeevan, Sam John, and Soney C. George
Elsevier BV
M. Manuja, Tintu Thomas, Sam John, Joshy Jose, and Gijo Jose
Elsevier BV
Abstract 2D nanoflake structures of orthorhombic WO30.33H2O are prepared using the hydrothermal procedure and subjected to conductivity and electrochemical studies. Permittivity measurements from ac conductivity study and I-V characteristics from DC conductivity measurements point toward the energy storage efficiency of the material. Cyclic voltametry measurements support the observations and demonstrate the dominant battery like behavior with 93.99% diffusion controlled and 6.01% surface controlled process occurring in the sample. Chronoamperometry explains the fastest coloration and bleaching time (tc=0.46 s and tb=0.98 s) ever reported. Finally, WO30.33H2O is proved to be a good cathode material in the assembly of WO30.33H2O/KCl/Mg as a solid state battery.
Sreelakshmi Rajeevan, Sam John, and Soney C George
Elsevier BV
S. Muthulingam, K.P. Greeshma, K. Poornima, R. Tamizselvi, Sam John, and A.P. Uthirakumar
Elsevier BV
Zachariah Pulluparampil Mathew, Keerthi Rajan, Cyril Augustine, Bincy Joseph, and Sam John
Elsevier BV
Effective inhibition of metallic corrosion to prevent its consequent loss is one of the serious apprehensions for industries in the modern world. This paper analyses the application of poly(2-ethyl-2-oxazoline) (PEOX) as an effective inhibitor of corrosion, when it is made to be in contact with the surfaces of mild steel (MS). The sustainability of MS against corrosion in 0.1 M Hydrochloric acid solution in the presence of known concentration of PEOX is assessed by potentiodynamic polarization (PDP) measurements, linear polarization studies (LPR), and electrochemical impedance spectroscopy (EIS). It was observed that PEOX behaves as better inhibitor for mild steel corrosion in 0.1 M HCl solution and it show enhanced inhibition efficiency (IE%) 79% at a concentration of 50 ppm. The polarization experiments indicated that addition of PEOX in concentrations varies from 25 ppm to 50 ppm induces a decrease of both cathodic and anodic currents densities. Also, the micrographs recorded by the Scanning Electron Microscopy confirm that molecules of PEOX act as corrosion inhibitors for the surfaces of MS in 0.1 M HCl. The stability of the MS surface in a corrosion-prone environment is traced by measuring the contact angles of water droplets placed on the MS surface, to quantify the extent of deterioration, if any, due to corrosion. The results presented here show that the compound PEOX performs as a mixed-type inhibitor against corrosion at the MS surface in acidic medium. Theoretical studies based on the electronic structure of PEOX in aqueous medium also support its performance as a successful corrosion-inhibitor.
T. Sajini, Sam John, and Beena Mathew
Royal Society of Chemistry (RSC)
Attempts have been made to investigate the feasibility of fabricating an enantiomeric sensor for the specific detection of d-mandelic acid layered on vinyl-MWCNT using molecular imprinting technology.
T. Sajini, Sam John, and Beena Mathew
Elsevier BV
Abstract The present work is aimed to the fabrication of enantioselective sorbent and sensor for the selective and specific recognition of L-phenylalanine benzyl ester (L-PABE) template molecule in photo-responsive molecularly imprinted polymer (PR-MIP). Here a photo-switchable azo-benzene derivative, 4-[(4-methacryloyloxy)phenylazo]benzoic acid (MPABA) is synthesised and used as the functional monomer. Composites of multiwalled carbon nanotubes (MWCNTs) and imprinted polymer were prepared using 1:4 mol imprinting ratio of L-PABE and MPABA and N,N-ethylene bismethacrylamide (EBMAA) as the crosslinking agent. Conventional bulk MIP and their respective non-imprinted polymers were also synthesised and characterized to investigate the influence of pre-organization of binding sites on the selectivity of L-PABE. The enantioselective sensor is fabricated on platinum working electrode using imprinted and non-imprinted polymers and their electrochemical measurements are investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and elctrochemical impendence spectroscopy (EIS). The platinum modified sensors possess a limit of detection and limit of quantification as 0.2086 μmol L−1 and 0.6953 μmol L−1 respectively. MWCNT-MIPs and MIPs exhibit the largest adsorption capacity towards L-PABE. The synthesised polymers reveal characteristic adsorption features and selectivity towards L-PABE in comparison with its enantiomer analogues. Photo-regulated uptake and release studies of MWCNT-MIP and MIP on L-PABE were also done to determine the photoswitching reversibility of functional monomer.
Sam John, Alfeena Salam, Anju Maria Baby, and Abraham Joseph
Elsevier BV
Abstract Coatings tailored to corrosion protection of metallic substrates are of utmost relevance to ensure reliability and long-term performance of coated parts as well as the product value of the coated materials. Presently, there is a strong emphasis on the development of advanced functional and smart coatings for corrosion protection in different technological applications. This work aimed to develop a novel coating based on Chitosan Titanium dioxide (CS/TiO2) nanocomposite to evaluate its corrosion inhibition effect on mild steel. Chitosan Titanium dioxide (CS/TiO2) nanocomposite films were coated on mild steel by sol–gel process, dip coating technique. Sol–gel protective coatings have shown excellent chemical stability, oxidation control and enhanced corrosion resistance for metal substrates. Further, the sol–gel method is an environment friendly technique of surface protection which has traditionally been used for increasing corrosion resistance of metals. For this project, Chitosan Titanium dioxide (CS/TiO2) nanocomposite membranes were prepared using Tetrabutyl Titanate (TBT) as precursor and acetyl acetone as chelating agent by solution casting process. The prepared nanocomposite membranes were coated on a polished metal surface, dried and annealed at 120 °C for two hours. Corrosion protection behavior of these coated mild steel substrates in 0.1 N HCl solutions was evaluated by potentiodynamic polarization studies (Tafel), linear polarization studies (LPR), electrochemical impedance spectroscopy studies (EIS).
Rugmini Ammal P, Anupama R Prasad, Ramya K, Sam John, and Abraham Joseph
Informa UK Limited
Abstract The corrosion protection efficiency of MBIMOT, 5-((2-methyl-1H-benzo[d]imidazol-1-yl) methyl)-1, 3, 4 oxadiazole-2-thiol towards mild steel (MS) in HCl and its variation with inhibitor concentration, acid concentration and temperature were assessed by weight loss and electrochemical methods. Corrosion rate found to decrease with increasing the concentration of MBIMOT and increase with temperature and acid concentration. Electrochemical impedance spectroscopy studies revealed that the adsorption of MBIMOT on MS surface follow Langmuir isotherm. The mixed type behavior of MBIMOT is evidenced from the polarization curves. Various kinetic and thermodynamic parameters were calculated. The molecular level understanding of corrosion inhibition done by DFT approach revealed a preferential adsorption of thione form of MBIMOT over thiol form on MS surface.
Sam John, James Baben George, and Abraham Joseph
Author(s)
The optical properties of the semiconducting nanomaterials has a wide variety of applications in the biological and industrial fields, which include the synthesis of UV laser, light emitting diodes, solar cells, gas sensors, piezoelectric transducers etc. Among the various types of optical properties, luminescence especially photoluminescence (PL) of metal oxides are more prominently studied. This is because PL spectrum is an effective way to investigate the electronic structure, optical and photochemical properties of semiconductor materials which deciphers information such as surface oxygen vacancies, defects, efficiency of charge carrier trapping, immigration, transfer etc. To overcome the drawbacks in luminescence studies of metal oxide nanomaterials, polymer technology has also been incorporated. The scientists found that the doping of some elements into the polymer capped ZnO nanocomposites enhanced the luminescence properties of the compound. In the current study, we are investigating the photoluminescence properties of ZnO nanocomposites capped with a biodegradable polymer poly (2-ethyl 2-oxazoline) and doped with the elements Cobalt and Zirconium. We obtained many strong fluorescence peaks in the visible and UV regions in the PL spectrum and UV absorption spectroscopy.The optical properties of the semiconducting nanomaterials has a wide variety of applications in the biological and industrial fields, which include the synthesis of UV laser, light emitting diodes, solar cells, gas sensors, piezoelectric transducers etc. Among the various types of optical properties, luminescence especially photoluminescence (PL) of metal oxides are more prominently studied. This is because PL spectrum is an effective way to investigate the electronic structure, optical and photochemical properties of semiconductor materials which deciphers information such as surface oxygen vacancies, defects, efficiency of charge carrier trapping, immigration, transfer etc. To overcome the drawbacks in luminescence studies of metal oxide nanomaterials, polymer technology has also been incorporated. The scientists found that the doping of some elements into the polymer capped ZnO nanocomposites enhanced the luminescence properties of the compound. In the current study, we are investigating the photolumi...
Sam John, R. Jeevana, K.K. Aravindakshan, and Abraham Joseph
Elsevier BV
Abstract Two N(4)-substituted thiosemicarbazones, anisoin- and furoin N(4)-methyl(phenyl) thiosemicarbazone (AMPTSC and FMPTSC, respectively) have been tested as inhibitors on the corrosion of mild steel in 1 M HCl solution using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) methods, adsorption studies and surface morphological studies. Polarization measurements revealed the mixed type inhibitor character. The inhibiting action of these molecules is discussed in terms of blocking the electrode surface by the adsorption of inhibitor molecules obeying Langmuir isotherm. The lowest corrosion rate was obtained with FMPTSC. Surface morphological studies also gave unfailing results.
Mathew Kuruvilla, Anupama R. Prasad, Sam John, and Abraham Joseph
Springer Science and Business Media LLC
Amino acids have been categorized as green corrosion inhibitors due to their unique properties such as non-toxic and biodegradable nature. Considering its great importance in corrosion chemistry, studies were undertaken with an objective to find out the interaction behaviour of amino acids such as cysteine and alanine on corrosion inhibition of copper in 1 M sulfuric acid at varying temperatures such as 303, 308 and 313 K. Various techniques such as weight loss method, electrochemical impedance spectroscopy, potentiodynamic polarization (Tafel), basic computational calculations and adsorption studies were employed in the present investigations. Results revealed the synergic interaction of amino acids cysteine and alanine with attractive corrosion inhibition efficiency in 1 M concentration of sulfuric acid. The inhibition effect of amino acid cluster advanced with the increased concentration of the inhibitor. However, with the increase in temperature, the inhibition efficiency showed a declining trend. Such behaviour of the amino acids on copper in sulfuric acid medium may be due to surface adsorption of the inhibitor molecules on the metal which contributes to decrease in the double layer capacitance and increase in the polarization resistance.
Sam John, Abraham Joseph, Mathew Kuruvilla, and Sajini T
Springer Science and Business Media LLC
Coatings tailored to corrosion protection of metallic substrates are of the utmost relevance to ensure reliability and long-term performance of coated parts as well as the product value of the coated materials. Presently, there is a strong emphasis on the development of advanced functional and smart coatings for corrosion protection in different technological applications. This work aimed to develop a novel coating based on chitosan and PVA to evaluate its corrosion inhibition effect on mild steel. Chitosan/PVA films were coated on mild steel by dip coating technique. Sol–gel protective coatings have shown excellent chemical stability, oxidation control and enhanced corrosion resistance for metal substrates. Further, the sol–gel method is an environmentally friendly technique of surface protection which has traditionally been used for increasing corrosion resistance of metals. Films so formed were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), the thermal property of the chitosan–PVA film was examined by differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Corrosion protection behavior of these coated mild steel substrates in 0.1 N HCl solutions was evaluated by potentiodynamic polarization studies (Tafel), linear polarization studies (LPR), and electrochemical impedance spectroscopy studies (EIS). The experimental results showed that the chitosan/PVA composite coatings were superior to pure chitosan in corrosion protection. EIS measurements and Tafel polarization method have proven that corrosion resistance of mild steel in 0.1 N HCl solutions, increases with increasing the number of layers of chitosan/PVA films. The results indicated that the polymer film adhered to the mild steel surface and inhibited the mild steel corrosion in 0.1 N HCl.