Browsing by Author "Bhat, R.S."

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An improved bound on weak independence number of a graph
(2013) Bhat, R.S.; Kamath, S.S.; Surekha
A vertex v in a graph G=(V,X) is said to be weak if d(v)â‰¤d(u) for every u adjacent to v in G. A set S âŠ† V is said to be weak if every vertex in S is a weak vertex in G. A weak set which is independent is called a weak independent set (WIS). The weak independence number wÎ²0(G) is the maximum cardinality of a WIS. We proved that wÎ²0(G)â‰¤ p-Î´. This bound is further refined in this paper and we characterize the graphs for which the new bound is attained.
Bio-inspired helicoidal hemp/basalt/polyurethane rubber bio-composites: Experimental, numerical and analytical ballistic impact study with residual velocity prediction using artificial neural network
(Elsevier B.V., 2024) Gowda, D.; Bhat, R.S.
Recent body armour trends emphasize mobility, flexibility, and cost reduction while maintaining ballistic effectiveness through the use of natural fiber composite. This study evaluates the ballistic impact performance of soft and hard armor using experimental, analytical, numerical, and machine learning methods. We developed a soft armor bio-composite using monolithic, hybrid, and helicoidal structured Hemp (H)/Basalt (B)/Polyurethane (PU) rubber and tested its V50 ballistic limit according to Millitary-Standred-662 F. For hard armour, a multi-layer armor system (MAS) consisting of Al2O3/SiC ceramic, intermediate soft armour bio-composites, and an Aluminum (Al)-5052 plate backing was tested with armour-piercing bullets as per National Institute of Justice (NIJ)-0101.06 standards (Level IV). Soft armor performance was evaluated using macro-homogeneous finite element (FE), the Ipson-Retch analytical, and an Artificial Neural Network (ANN) regression model. Results showed minimal discrepancies from experimental data, with differences of 13.33 %, 12.08 %, and 8.08 % in V50 ballistic limit. The mechanical and thermal behaviors of bio-composites were assessed using un-notched Charpy, FTIR, and TGA methods. Helicoidal laminates improved Charpy toughness by 9.44 %, 19.30 %, and 40.28 % compared to hybrid and monolithic ([H]15 and [H]10) laminates, and exhibited lower weight reduction at high degradation temperature of 395.76 ?. Helicoidal laminates increased V50 ballistic performance by 155.80 %, 76.22 %, and 16.61 % compared to [H]10, [H]15, and hybrid laminates, respectively. Due to spiral load distribution reduces stress concentration and enhanced the damage resistance of the laminate. Stand-alone soft armor demonstrates crater formation and radial cracks (petaling) due to fiber wedging and the shearing effect of a bullet. In conclusion, MAS revels a maximum back face deformation (BFD) of 18.06 mm. Al2O3/Helicoidal/Al-plate MAS reduced weight and cost by 69.21 %, and 233.72 % compared to Kevlar™-based MAS, promoting sustainable, lightweight, economical designs. Due to its higher fracture toughness and lower density, SiC ceramic in MAS provides lower trauma and further reduced weight compared to Al2O3 ceramic. © 2024 Elsevier B.V.
Compositionally Modulated Multilayered Zn-Co Deposits for Better Corrosion Resistance
(Springer, 2020) Bhat, R.S.; Venkatakrishna, K.; Nayak, J.; Hegde, A.C.
Zn-Co compositionally modulated multilayer alloy (CMMA) deposits have been developed onto mild steel using single bath technique. Multilayer alloy coatings have been galvanostatically produced using square current pulses. The switched cathode current density and number of layers have been designed for improved corrosion resistance. Experimental data revealed that multilayer coating with 120 layers at 10/30 mA/cm2 demonstrated ~ 125 times higher resistance to corrosion than monolayer alloy coating of the same thickness. The improved corrosion resistance of multilayer coatings is due to small changes in the wt.% cobalt, leading to change in the phase structure of deposit in alternate layers. The defects and failures occurring in a single layer in the deposition process are covered by the alternatively deposited coating layers. Therefore, the direction of the corrosive agent is extended or blocked. Further, the better corrosion resistances afforded by Zn-Co CMMA coatings were explained through changes in electronic properties at the interface, supported by Mott-Schottky’s plot. However, the decrease of corrosion resistance at a high degree of layering is attributed to the less relaxation time for redistribution of solutes in the diffusion layer, during plating. Potentiodynamic polarization and electrochemical impedance data showed its good protection ability. The enhanced corrosion resistance of multilayered deposits is due to small change in cobalt content, leading to alter the phase structure of the alternate-layers of the deposits. The structural morphology and the topographical structure of the coating were analyzed by scanning electron microscopy and atomic force microscopy. Evaluation of the chemical composition of the alloy coatings was carried out by x-ray photoelectron spectroscopy. © 2020, ASM International.
Corrosion behavior of electrodeposited Zn-Ni, Zn-Co and Zn-Ni-Co alloys
(2011) Bhat, R.S.; Bhat, U.; Hegde, A.C.
Zn-Ni, Zn-Co and Zn-Ni-Co alloy coatings were electrodeposited galvanostatically using sulphate bath, having THC as additive. The bath composition and operating parameters have been optimized by standard Hull cell method. The effects of current density (c.d.), pH on composition, thickness, hardness of the deposit were studied. Under all conditions of deposition, the bath followed anomalous type of codeposition with preferential deposition of less noble metal. Corrosion resistances of the coatings were measured by potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) method showed that under optimal conditions, the corrosion resistance of Zn-Ni-Co alloy coatings is approximately 20 times and 18 times better than Zn-Ni and Zn-Co alloys of same thickness. The Zn-Ni-Co coating under optimal c.d. (3.0 A dm-2) was found due to its inherent high dielectric barrier, evidenced impedance signals. High partial c.d. for zinc in Zn-Ni-Co alloy system supports the possibility of a synergistic catalytic effect of Co on Fe and vice versa. X-ray diffraction study clearly indicates that improved corrosion resistance of ternary alloy is due to the change in the phase structure of the coatings, compared to binary alloys. Surface morphology and composition of the coatings were examined by using Scanning Electron Microscopy (SEM), interfaced with EDX facility, respectively. The ternary Zn-Ni-Co coating may thus replace the conventional Zn-Ni and Zn-Co coatings in a variety of applications. © 2011 by CEE.
Corrosion behavior of Zn-Co alloy coating from acid sulphate bath
(Center of Excellence in Electrochemistry, Univ. of Tehran, 2014) Bhat, R.S.; Hegde, A.C.
Optimization of sulphate bath for deposition of a smooth and uniform Zn-Co alloy over mild steel is discussed in the present work. Electrodeposition was done using Thiaminehydrochloride (THC) and citric acid (CA) as additives in combination. The bath followed anomalous codeposition with preferential deposition of Zn over noble Co. The experimental results reveal that a bright Zn-Co alloy having ~1.06 wt. %Co was showing peak performance against corrosion in compliance with other physical properties like reflectance, hardness, thickness and adhesion. The dependency of bath composition, current density, partial current density, pH and temperature on deposit properties like reflectivity, corrosion resistance were discussed. Deposition was carried out under different condition of c.d.’s and molar ratio of [Co+2]/[Zn+2]. No transition c.d.’s at which codeposition behavior changed from anomalous to normal type was observed. Cyclic polarization measurement was performed to study the nature of corrosion taking place in the corrosion cell. An electrochemical behavior of Zn-Co alloy electrodeposition in alkaline solutions was studied using cyclic voltammetry technique. The increase in the corrosion resistance of coatings attributed to the formation of n-type semiconductor film at the interface was confirmed by Mott-Schottky (M-S) plot with straight line having positive slope. The composition of deposits were determined by colorimetric method and confirmed by EDX analysis. Surface morphology of the deposits was examined using scanning electron microscopy (SEM). The phase content was examined by XRD analysis at different current densities. A stable acid sulphate bath has been proposed for bright and uniform deposit of Zn-Co over mild steel and discussed. © 2014 by CEE.
Corrosion stability of electrodeposited cyclic multilayer Zn-Ni alloy coatings
(2011) Bhat, R.S.; Udupa, K.R.; Hegde, A.C.
This paper reports on a study of electrodeposition and characterisation of cyclic multilayer coatings of Zn-Ni alloy from a sulphate bath. Cyclic multilayer alloy coatings were deposited on mild steel through the single bath technique by appropriate manipulation of cathode current densities. The thickness and composition of the individual layers of the CMA deposits were altered precisely and conveniently by cyclic modulation of the cathode current during electrodeposition. Multilayer deposits with sharp change in composition were developed using square current pulses, using thiamine hydrochloride and citric acid as additives. Laminar deposits with different configurations were produced and their corrosion behaviours were studied by AC and DC methods in 5%NaCl solution. It was observed that the corrosion resistance of the CMA coating increased progressively with the number of layers (up to certain optimal numbers) and then decreased. The decrease in corrosion resistance at high degree of layering was attributed to interlayer diffusion due to less relaxation time for redistribution of metal ions at cathode during deposition. The coating configurations have been optimised for peak performance of the coatings against corrosion. It was found that CMA coating developed at cyclic cathode current densities of 3.0/5.0 A dm-2 with 300 layers showed the lowest corrosion rate (0.112×10-2 mm/year) which is ?54 times better than that of monolithic Zn-Ni alloy, deposited from the same bath. The protection efficacy of CMA coatings is attributed to the difference in phase structure of the alloys in successive layers, deposited at different current densities, evidenced by X-ray diffraction analysis. The formation of multilayers and corrosion mechanism were examined by scanning electron microscopy. © 2011 Institute of Metal Finishing.
Development of nano-structured cyclic multilayer Zn-Ni alloy coatings using triangular current pulses
(2011) Bhat, R.S.; Hegde, A.C.
Cyclic multilayer alloy (CMA) deposits of Zn-Ni were developed on mild steel from sulphate bath having thiamine hydrochloride (THC) and citric acid (CA) as additives. CMA coatings were developed galvanostatically using triangular current pulses, under different conditions of cyclic cathode current density (CCCD's) and number of layers. The corrosion behaviors of the coatings were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy methods, and were compared with that of monolayer Zn-Ni alloy of same thickness. At optimal configuration, CMA coating represented as, (Zn-Ni)2.0/5.0/300 was found to exhibit ?40 times better corrosion resistance compared to monolayer alloy, (Zn-Ni)3.0. Cyclic voltammetry study demonstrated that THC and CA have improved the appearance of the deposit by complexation with metal ions. The corrosion protection efficacy of CMA coatings was attributed to the difference in phase structure of the alloy in successive layers, evidenced by XRD analysis. The formation of multilayer and corrosion mechanism was analyzed by Scanning Electron Microscopy (SEM) study. © 2011 Allerton Press, Inc.
Development of nano-structured Zn-Ni multilayers and their corrosion behaviors
(2011) Yogesha, S.; Bhat, R.S.; Venkatakrishna, K.; Pavithra, G.P.; Ullal, Y.; Hegde, A.C.
Composition modulated multilayer alloy (CMMA) coatings of Zn-Ni was developed using single bath technique (SBT). CMMA coatings were developed galvanostatically using square current pulses. The cyclic cathode current densities (CCCDs) and number of layers were optimized for highest corrosion resistance. Experimental results showed that CMMA coating, developed at 2.0/5.0 A/dm2, having 300 layers is ?29 times higher corrosion resistant than monolithic alloy of same thickness. Tafel and impedance data revealed its good protection ability. The improved corrosion behavior exhibited by multilayers was explained using dielectric spectroscopy. The formation of multilayer and corrosion mechanism was analyzed using scanning electron microscopy (SEM). Copyright © Taylor & Francis Group, LLC.
Electrochemical Detection of Catechol using Synthesized Titanium Oxide Nanoparticles
(Center of Excellence in Electrochemistry, Univ. of Tehran, 2025) Bindu, A.G.; Bhat, R.S.; Shivani; Hegde, A.
The fabrication of advanced electrodes has garnered significant attention due to their exceptional sensitivity and selectivity for detecting catechol samples. Titanium dioxide nanoparticles (TiO2 NPs) have emerged as highly effective modifiers for carbon paste electrodes (CPEs), attributed to their unique electrochemical characteristics and enhanced conductivity. In this study, TiO2 NPs are prepared via the combustion method (CM), offering a reliable strategy for boosting electrode performance. This work aims to synthesize the TiO2 NPs by using Titanium (III) sulfate as precursor materials, and citric acid as fuel to get the desired TiO2 NPs. The confirmation of NPs is done through various techniques such as field emission scanning microscopy (FESEM), microstructure analysis by XRD, elemental composition by EDS, and absorption vibration levels by Raman spectroscopy. TiO2 NPs are used for the development of electrode applications to determine catechol (CC) using carbon paste electrodes (CPE). The electrode surface is modified into a TiO2 composite carbon paste electrode (TiCCPE). The electrochemical techniques are performed using a phosphate buffer solution (BS) of 0.1 M at a pH range of 7.0 of a two-electron transfer system with scan rates variation from 0.50-0.400 V/s signifies reaction of absorption-controlled process, and concentration studies from 0.2 µM to 1.6 µM with detection and quantification limit of 0.21 µM and 0.71 µM and was found using Linear sweep voltammetry technique (LSV). The electrode modification associated with synthesized TiO2 NPs assists in an outstanding way to sense the CC, as good sensitivity, stability, selectivity, and reproducibility of catechol detection were assessed using electrochemical techniques throughout the studies. © 2025, Center of Excellence in Electrochemistry, Univ. of Tehran. All rights reserved.
Electrochemical determination of ascorbic acid using carbon paste electrode modified with cobalt oxide nanoparticles
(Elsevier Ltd, 2025) G, B.A.; Bhat, R.S.; Hegde, S.S.; Badekai Ramachandra, B.R.
The present work introduces a cobalt oxide nanoparticle-modified carbon paste electrode (Co2O3/CPE) as a simple, low-cost, and efficient platform for the electrochemical determination of ascorbic acid. This study shows the excellent selectivity of the electrode against common interferents, linear detection range, low detection limit, and reproducibility, making it a promising substitute to expensive noble-metal-based sensors for real-sample ascorbic acid analysis. An eco-friendly novel electrochemical study is carried out to detect ascorbic acid (ACA) using a Congo red (CR) modified cobalt oxide nanoparticle (Co3O4) composite carbon paste electrode (CRMCCCPE). This CRMCCCPE significantly enhanced the electrochemical performance for the selective and sensitive analysis of ACA. The elemental analysis of the synthesised Co3O4 by EDX (energy-dispersive X-ray spectroscopy), the phase structure through XRD (X-ray diffraction), and the absorbance peaks by Raman spectrometry with 37.41 nm. The surface topography by FESEM (field emission scanning electron microscopy). Voltammetric techniques and EIS (electrochemical impedance spectroscopy) are investigated for the electrochemical redox response of ACA in phosphate buffer (PB) of 0.1 M concentration across the various ranges of pH at a 0.1 V/s scan rate. The ACA detection through the impact of pH, impact of scan rate, concentration, interference, simultaneous detection, and real sample analysis, indicating CV at 0.2 ?M to 2.4?M, DPV at 0.2 ?M to 2.6?M and LSV at 0.2 ?M to 2.4?M, with a lower limit of detection (LOD) were CV is 1.4 ??, DPV is 0.7 ?M, and LSV is 1.5 µ? and quantification (LOQ) was CV is 4.8 ?M, DPV is 2.6 µM, and LSV is 5.0 ?M. The fabricated CRMCCCPE exhibits the novelty of excellent stability, reproducibility, and repeatability, suggesting its potential application for the electrochemical recognition of ACA in complex matrices. The results indicate that CRMCCCPE is a reliable and effective platform for voltammetric sensing of ACA, offering promising applications in food quality control and medicinal diagnostics. © 2025 Elsevier Ltd.
Electrochemical Studies of Zn-Ni-Fe Alloy Coatings for Better Corrosion Resistance Applications
(Springer, 2022) Bhat, R.S.; Munjunatha, K.B.; Bhat, S.I.; Venkatakrishna, K.; Hegde, A.C.
Anti-corrosive alloy coatings are a valuable solution to the protection of low carbon steel structures/equipment against corrosion. The Zn-Ni-Fe coatings have been deposited galvanostatically on low carbon steel from an acid chloride bath. Sulfanilic acid and gelatin were used as additives for the homogeneity of the deposit. The Hull cell method has been used to optimize both bath constituents and plating conditions. The corrosion behavior of the coating films was examined with potentiodynamic polarization and the electrochemical impedance spectroscopy methods. The effects of current density, pH, and temperature on deposit properties like hardness, thickness, and corrosion rates were examined. The electrochemical characteristics of the Zn-Ni-Fe have been studied by the cyclic voltammetry technique. The morphology of the deposit was investigated with scanning electron microscopy and the surface roughness of the coating film was analyzed by atomic force microscopy. The Ni and Fe contents in the deposit were analyzed by colorimetric technique and cross-checked with energy-dispersive x-ray analysis. The capacitive reactance at the interface is attributed to the excellent corrosion resistance at optimal current density (40 mA cm−2) as indicated by the Nyquist plot with large polarization resistance. Furthermore, the positive slope of Mott-Schottky revealed that the semiconductor film at the interface is n-type. The results show that a new Zn-Ni-Fe alloy coating film exhibits better corrosion resistance properties and can be executed in industrial applications such as machine tools, bolts, and nuts in the automobile for corrosion protection, etc. © 2022, ASM International.
Electrochemical studies on the corrosion resistance of Zn–Ni–Co coating from acid chloride bath
(Springer, 2020) Bhat, R.S.; Manjunatha, K.B.; Prasanna Shankara, R.; Venkatakrishna, K.; Hegde, A.C.
Anticorrosive deposits are a valuable approach to defending against corrosion from mild steel structures/machinery equipment. The Zn–Ni–Co coating has been deposited on low carbon steel surfaces using environment friendly optimized acidic chloride bath with ZnCl2·6H2O, NiCl2·6H2O, CoCl2·6H2O, sulphanilic acid (C6H7NO3S) and gelatin (C6H8O6). The standard Hull cell technique has been adopted for the optimization of bath components and experimental conditions, for the superior corrosion resistant coating. The corrosion test with potentiodynamic polarization method was performed to investigate the role of pH on the film quality and corrosion performances of the films. Further, the effect of current densities on corrosion resistance, thickness and hardness, have been investigated. Cyclic voltammetry technique has been used to test the electrochemical properties of the Zn–Ni–Co coating in acidic solutions. The results revealed that the increase in the current density favoured the increase in Ni and Co content in the deposit, showed higher corrosion resistance and higher cathodic current efficiency. The structural and morphological characteristics of the alloy coating have been obtained through scanning electron microscopy and X-ray diffraction techniques. The atomic force microscope was used to examine the topographic structure of the coating. X-ray Photoelectron spectroscopy was used to determine the chemical composition of alloy coatings and verified by energy dispersive X-ray analysis. The results indicate that a new and low-cost chloride bath for Zn–Ni–Co coating exhibit superior corrosion resistance properties and can be implement in various industrial applications such as automobiles, machine tools etc.[Figure not available: see fulltext.]. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
Electrochemical study of Zn-Fe alloy coatings on mild steel for automotive applications
(Chulalognkorn University, 2025) Bhat, R.S.; Hegde, A.
This study investigates the electrochemical behavior of Zn-Fe alloy deposited on mild steel (MS) substrates for automotive applications. The electrodeposition of a Zn-Fe alloy onto MS using an acid chloride bath, with 1,2,4-Triazole as an additive to enhance the uniformity of the deposit. The hull cell method was used to optimize the bath composition and operating conditions. The coatings were produced using electrodeposition at varying current densities, with 3 A?dm?2 identified as the optimal current density (CD) for achieving uniform coatings. The microstructural properties, including crystallite size and micro-strain, were analyzed using X-ray diffraction (XRD) and Williamson-Hall (W-H) analysis, revealing a homogenous distribution of crystallite size and strain. The impact of CD on coating features such as hardness, cathode current efficiency (CCE), thickness, and the weight % of metal contents was investigated. The corrosion resistance of the deposit was estimated using the potentiodynamic polarization and electrochemical impedance spectroscopy methods, and the results have been discussed. The structural and morphological properties of the deposit were investigated by Scanning electron microscopy (SEM). The roughness of the deposit was studied by Atomic force microscopy (AFM). The deposits containing Zn and Fe contents were confirmed by Energy-dispersive spectroscopy (EDS). The results suggest that Zn-Fe alloy coatings can provide superior protection for automotive components. © (c) 2025 Journal of Metals, Materials and Minerals. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Electrodeposition of Zn–Co Coating and its Electrochemical Performance
(Pleiades journals, 2022) Bhat, R.S.; Manjunatha, K.B.; Venkatakrishna, K.; Hegde, A.C.
Abstract: We report the acid chloride bath based electroplating of Zn–Co alloy on low carbon steel (LCS). As additives, the sulphanilic acid (SA) and gelatin were used for electroplating. The bath exhibited an anomalous co-deposition with a higher deposition of Zn over nobler Co. The role of bath composition, current density, partial current density, pH, and temperature on thickness, hardness, and corrosion resistance of deposit was studied. The corrosion behavior in 3.5 wt % sodium chloride solution and electrochemical behavior in acid chloride solutions of Zn–Co alloy coatings were studied using the potentiodynamic polarization method and cyclic voltammetry technique respectively. Mott–Schottky plot with positive slope confirms the development of n-type semiconductor layer at the interface of substrate and coating, which results in superior corrosion resistance of coatings. The colorimetric method has been used to estimate the composition of the deposit and further verified by energy dispersive X-ray spectroscopy (EDX) technique. The surface features and the topographical structure of the alloy film were obtained by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The results indicate that the Zn–Co alloy films exhibited superior corrosion resistance with the lowest corrosion rate (138 µm y–1). Hence this alloy coating will find suitable applications in automobile and aerospace industries. © 2022, Pleiades Publishing, Ltd.
Electroplating and corrosion study of Zn-Co, Zn-Fe and Zn-Co-Fe alloys
(2012) Bhat, R.S.; Chitaranjan Hegde, A.
Zn-Co, Zn-Fe and Zn-Co-Fe coatings were electrodeposited on mild steel from an acid sulphate bath, using thiamine hydrochloride (THC) and citric acid (CA) as additives. Bath constituents and operating parameters were optimized by standard Hull cell method, for peak performance of the coatings against corrosion. The effect of current density (c.d.), pH on the deposit characters, such as corrosion resistance, hardness, thickness, partial current density and CCE were studied and discussed. Corrosion resistances were evaluated by Potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) method. Corrosion resistance of the Zn-Co-Fe coating under optimal c.d. (3.0 A dm-2) was found due to its inherent high dielectric barrier, evidenced impedance signals. High partial current density for zinc in Zn-Co-Fe alloy coating supports the possibility of a synergistic catalytic effect of Co on Fe and vice versa. X-ray diffraction study clearly indicates that a drastic change in corrosion resistance of ternary alloy is due to the change in the phase structure of the coatings, compared to binary alloys. Surface morphology and composition of the coatings were examined by using Scanning Electron Microscopy (SEM), interfaced with Energy Dispersive X-ray Analysis (EDXA) facility, respectively. © 2012 by CEE.
An improved bound on weak independence number of a graph
(2013) Bhat, R.S.; Sowmya, Kamath S.; Surekha
A vertex v in a graph G=(V,X) is said to be weak if d(v)?d(u) for every u adjacent to v in G. A set S ? V is said to be weak if every vertex in S is a weak vertex in G. A weak set which is independent is called a weak independent set (WIS). The weak independence number w?0(G) is the maximum cardinality of a WIS. We proved that w?0(G)? p-?. This bound is further refined in this paper and we characterize the graphs for which the new bound is attained.
Magnesium doped silver ferrite nanohybrid for identification of dihydroxybenzene isomers
(Elsevier Inc., 2025) Shivani; Bhat, R.S.; Sajankila, S.P.; Badekai Ramachandra, B.R.
The electrochemical identification of dihydroxybenzene isomers (DHBIs) using the magnetic transition metal oxide (TMO) nanohybrid is one of the best approaches for the study of electrochemical sensors. The DHBIs mainly include the catechol (CL), hydroquinone (HE), and resorcinol (RL). From this point of view, the ternary magnesium-doped silver ferrite (Mg-AgFe2O3) nanohybrid is prepared via the combustion approach, utilizing transition metal salts. The phase structure of the prepared nanohybrid is evaluated by X-ray diffraction (XRD). The surface characteristics were analyzed through Field emission scanning electron microscopy (FESEM). The elemental composition is confirmed by Energy dispersive X-ray (EDX) spectroscopy. The soft magnetic nature of the nanohybrid is evaluated by a Vibrating sample magnetometer (VSM). The prepared Mg-AgFe2O3 nanohybrid is fabricated on the glassy carbon electrode (GCE). The electrode surface is electro-polymerized with glycine, which forms the poly-glycine-reduced graphene oxide-Mg-AgFe2O3-GCE (PG-rGO-Mg-AgFe2O3-GCE). The enhanced electrochemical activity of the prepared electrode for DHBI detection is attributed to the synergistic interaction among the magnetic Mg–AgFe2O3 nanohybrid, reduced graphene oxide (rGO), and the PG diffusion layer. The electrode fabrication is examined through Electrochemical impedance spectroscopy (EIS). The fabricated GCE surface is studied for the electrochemical redox identification of DHBIs by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and differential pulse voltammetry (DPV) techniques. At the optimized pH, the modified electrode surface detects CL, HE, and RL at a limit of detection (LOD) and in the linear range of 0.039 µM (0.4–5.0 µM), 0.036 µM (0.3–3.5 µM), and 0.0086 µM (0.2–3.4 µM), respectively. The fabricated electrode simultaneously detects CL and RL is analyzed using the DPV method. The PG-rGO-Mg-AgFe2O3-GCE surface electrochemically identifies the CL, HE, and RL even in the presence of organic and inorganic interferents. Therefore, the modified electrode surface exhibits high specificity, sensitivity, repeatability, and reproducibility factors for electrochemical identification of the DHBIs. © 2025 Elsevier B.V.
On strong (weak) independent sets and vertex coverings of a graph
(2007) Kamath, S.S.; Bhat, R.S.
A vertex v in a graph G = (V, E) is strong (weak) if deg (v) ? deg (u)(deg (v) ? deg (u)) for every u adjacent to v in G. A set S ? V is said to be strong (weak) if every vertex in S is a strong (weak) vertex in G. A strong (weak) set which is independent is called a strong independent set [SIS] (weak independent set [WIS]). The strong (weak) independence numbers ? = s ? (G) (w ? = w ? (G)) is the maximum cardinality of an SIS (WIS). For an edge x = uv, v strongly covers the edge x if deg (v) ? deg (u) in G. Then u weakly covers x. A set S ? V is a strong vertex cover [SVC] (weak vertex cover [WVC]) if every edge in G is strongly (weakly) covered by some vertex in S. The strong (weak) vertex covering numbers ? = s ? (G)(w ? = w ? (G)) is the minimum cardinality of an SVC (WVC). In this paper, we investigate some relationships among these four new parameters. For any graph G without isolated vertices, we show that the following inequality chains hold: s ? ? ? ? s ? ? w ? and s ? ? w ? ? ? ? w ?. Analogous to Gallai's theorem, we prove s ? + w ? = p and w ? + s ? = p. Further, we show that s ? ? p - ? and w ? ? p - ? and find a necessary and sufficient condition to attain the upper bound, characterizing the graphs which attain these bounds. Several Nordhaus-Gaddum-type results and a Vizing-type result are also established. © 2006.
Optimization of bright Zn-Co-Ni alloy coatings and its characterization
(2013) Bhat, R.S.; Hegde, A.C.
Acidic sulphate bath having ZnSO4.7H2O, CoSO4.7H2O, NiSO4.7H2O and thiamine hydrochloride (THC) and citric acid (CA) in combination, was optimized for deposition of bright Zn-Co-Ni alloy coating on mild steel. Bath constituents and operating parameters were optimized by Hull cell method, for highest performance of the coating against corrosion. The effect of current density (c.d.), on deposit characters, such as corrosion resistance and hardness, thickness were studied and discussed. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods were used to assess the corrosion behaviors. The composition of deposits were determined by spectrophotometeric method and confirmed by EDX analysis. Surface morphology of the deposits was examined using scanning electron microscopy (SEM). The Zn-Co-Ni alloy, with intense peaks corresponding to Zn (100) and Zn (101) and Zn (110) phases, showed highest corrosion resistance, evidenced by X-ray diffraction (XRD) study. A new and cheap sulphate bath, for bright Zn-Co-Ni alloy coating on mild steel has been proposed, and results are discussed. © 2013 by CEE.
Production of layer by layer Zn-Fe compositional multilayer alloy coatings using triangular current pulses for better corrosion protection
(Maney Publishing, 2015) Bhat, R.S.; Hegde, A.
Multiple-layer coatings of Zn-Fe alloy having alternatively the same compositions have been developed galvanostatically on mild steel (MS) from a single plating bath using triangular current pulses. Thiamine hydrochloride (THC) and citric acid (CA) were used as additives. Multiple-layer coatings were developed under different conditions of cyclic cathode current density (CCCD) and number of layers. Cyclic voltammetry demonstrated that the addition of THC and CA improves the deposit character by increasing the Ni content (through suppressing the deposition of Zn) via preferential adsorption on the cathode surface. The corrosion behaviours of the coatings were evaluated by electrochemical AC and DC methods. The optimum multiple-layer coating, represented as (Zn-Fe)3.0/5.0/300, was found to exhibit about four to five times better corrosion resistance when compared with monolayer (Zn-Fe)3.0 alloy, developed from the same bath for the same duration. Distinct phase structures responsible for interface formation between successive layers (which changes alternatively) were confirmed by X-ray diffraction analysis. Better corrosion resistance afforded by multiple-layer coating was attributed to the increased specific surface area of the coating because of layering. A synergistic effect of both structural difference between layers and individual layer thickness is responsible for enhanced corrosion resistance of the multiple-layer coatings. The formation of multiple layers and corrosion mechanism were analysed by scanning electron microscopy. © 2015 Institute of Materials Finishing.