Browsing by Author "Kumar, B."

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A Mechanistic Study on the Structure Formation of NiCo2O4 Nanofibers Decorated with In Situ Formed Graphene-Like Structures
(Springer New York LLC barbara.b.bertram@gsk.com, 2018) Kumar, B.; Gudla, V.C.; Ambat, R.; Kalpathy, S.K.; Anandhan, S.
Nickel cobaltite (NCO) nanofibers were synthesized using poly(styrene-co-acrylonitrile) (SAN) as the polymeric binder through sol–gel assisted electrospinning. Defect-free precursor nanofiber mats were pyrolyzed at 773 K at three different pyrolysis soaking times t = 2, 4, and 6 h. The SAN present in the precursor nanofibers caused morphological changes in the NCO nanofibers during their thermochemical degradation. Consequently, fractal aggregates of NCO nanoparticles were formed along the length of the nanofibers. X-ray photoelectron spectroscopy (XPS) revealed both + 2 and + 3 oxidation states for Ni and Co, with spinel crystal defects due to oxygen rich atmosphere. XPS, high-resolution transmission microscopy, and optical analysis showed graphene-like structures embedded within the NCO nanofibers. With increase in pyrolysis soaking time, the morphology of the NCO particles markedly changed from spherical to rod-like. We propose a mechanism for the morphological change of NCO nanoparticles on the basis of crystallite splitting accompanied by particle splitting and reordering. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.
An optimization study of microwave assisted extraction of oil from oily sludge using response surface methodology
(CAFET INNOVA Technical Society cafetinnova@gmail.com 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2014) Kumar, B.; Raj Mohan, B.
Petroleum oily sludge, a hazardous waste, generated by the refineries and at the production sites in huge quantities comprises of a mixture of petroleum hydrocarbons, asphaltenes, long chain paraffinic wax, waste water, sediments and metals. The present study is aimed to recover oil from the petroleum oily sludge using n-heptane as the solvent in microwave assisted solvent extraction process and to optimize the process variables for the recovery of oil from the oily sludge. The simultaneous effects of process variables such as irradiation time (2 - 10 minutes), solvent to sludge ratio (40 – 80 wt %), reactant volume (100 – 300 ml) and microwave power (80 – 400 W) on the recovery of oil were evaluated. A central composite design (CCD) and response surface methodology (RSM) were used for the optimization of the extraction process. Based on the CCD, quadratic model was developed to correlate the extraction process variables with the responses and the model was analysed using appropriate statistical method (ANOVA). Optimization of process variables shows that the maximum recovery of oil was about 88.6% at 100 ml of reactant volume with microwave power output of 351 W at 6.5 minutes of irradiation time with 58.99% of nheptane to sludge ratio. © 2014 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
Durability studies on ferrochrome slag as coarse aggregate in sustainable alkali activated slag/fly ash based concretes
(Elsevier B.V., 2020) Yaragal, S.C.; Kumar, B.; Jitin, C.
Utilization of industrial byproducts in concrete reduces carbon footprint, associated with production of ordinary Portland cement (OPC), and also indirectly controls rapid depletion of natural resources in the form of natural coarse aggregate (NCA). This study reports the durability effect of alkali activated slag/fly ash concretes (AASFC) with ferrochrome slag (FCS) as coarse aggregate. Different AASFC mixtures were prepared with two control factors i.e., fly ash (FA) content (0, 25, and 50% by weight as a replacement to Ground granulated blast furnace slag (GGBS)), and FCS content (0, 50, and 100% by volume as a replacement to NCA). Total nine mixtures were examined for three different durability tests i.e., volume of permeable voids (VPV), acid resistant test, and sulphate resistant test. Further, embodied energy (EE), and Embodied carbon dioxide emission (ECO2e) were also utilized to optimize the AASFC mixtures by grey relational analysis (GRA). Analysis of variance (ANOVA) is used as a statistical tool to investigate the effect of FA, and FCS content on the overall durability and ecological performance of AASFC mixtures. Results show that, addition of FA increases the durability performance (in % age), and addition of FCS decreases the durability performance (in % age) in AASFC mixtures. AASFC mixture with composition of 50% GGBS, 50% FA, and 100% FCS is considered as most suitable mixture. © 2019 Elsevier B.V.
Effect of Cryogenics-Assisted Low-Plasticity Burnishing on Laser-Clad Stellite 6 over SS420 Substrate
(Springer, 2020) Anirudh, P.V.; Kumar, B.; Girish, G.; Shailesh, S.; Oyyaravelu, R.; Kannan, C.; Balan, A.S.S.
The influence of modern additive manufacturing methods, especially from the direct energy deposition (DED) processes to the coat-like finished components, is crucial under present industrial circumstances. DED induces several traits like enhanced mechanical, thermal properties in shorter lead time, which extend their adaptation for diverse applications including aerospace and automobile industries. Among the several DED processes, laser cladding has been a prospect that explores various capabilities of improving the wear resistance of cobalt-chromium (Co-Cr)-based alloys. Rather than fabricating the complete component using expensive alloys, laser cladding has paved an approach to deposit particles possessing superior qualities over the conventional material. This research work attempts to evaluate the surface integrity of SS420 when cladded with Stellite 6. The vertical face milling is executed on the cladded component surface to facilitate either low-plasticity burnishing (LPB) or cryogenic burnishing (CB) as sequential post-treatment processes. The effects of these post-treatments on the surface and subsurface microhardness, surface topography and residual stress profiles are elaborated. Increased surface and subsurface microhardness, as well as improved residual stress profiles, are observed with CB over LPB-processed specimen samples. © 2020, ASM International.
Effect of elevated temperatures on ferrochrome ash based mortars
(Associated Cement Companies Ltd., 2019) Kumar, B.; Yaragal, S.C.; Das, B.B.
Due to boom in construction sector, large amount of Ordinary Portland Cement (OPC) is being consumed. Cement production is energy intensive and releases large amount of CO2 into atmosphere. Efforts are on to bring down cement consumption by the use of secondary cementitious materials. An attempt is made to study the influence of combined effect of various levels of ferrochrome ash (FCA) and lime, as replacement to OPC for different cement mortar mixtures at elevated temperatures. FCA replacement considered is in the range of 0% to 20% and along with 7% lime as replacement to cement. Compressive strength of cementitious materials is being an important parameter in the design of structures. The main objective of this work is to assess the residual compressive strengths at different levels of temperatures (200, 400, 600, and 800ºC) for a retention period of half an hour. Residual strengths of mortar mixtures produced, using FCA, have shown a good performance. Upto 20% FCA and 7% lime, mixture turns out to be a good elevated temperatures enduring material. This would increase the suggested application for environmental friendly materials. Important differences were seen in microstructural observations with scanning electron microscope (SEM) for various levels of FCA and lime incorporated mortars. © 2019, Associated Cement Companies Ltd. All rights reserved.
Effect of multidirectional forging on grain structure and mechanical properties of hypereutectic Al–20%Si alloys with added refiners and modifiers; Effet du forgeage multidirectionnel sur la structure des grains et les propriétés mécaniques des alliages hypereutectiques Al-20%Si avec des agents d’affinage et modificateurs ajoutés
(Taylor and Francis Ltd., 2025) Nagaraj, C.; Dutt, K.M.; Manjunath, G.K.; Sharath, P.C.; Sollapur, S.B.; B R, B.K.; Kumar, B.; Arunkumar, D.T.
The present work is focused on the multidirectional forging (MDF) of Al–20 wt-% Si alloys with the addition of refiners and modifiers. The MDF process was performed at 200°C with a cumulative strain of 0.63. Microstructural characterization and mechanical performance were evaluated on the Al–20Si, Al–20Si–4.5Cu, Al–20Si–4.5Cu–1(Al–Ti–B), Al–20Si–4.5Cu–1(Al–Ti–B)–10(Al–Sr). The microstructure analysis revealed significant changes in the eutectic and primary phase refinement. The micro-Vickers hardness confirmed that the MDF process resulted in increased hardness (125 ± 1.9 VHN) compared to the homogenized samples (96 ± 2.7 VHN). Tensile test results showed that with the accumulation of strain, ultimate tensile strength increased to 435 MPa from 302 MPa with reduction in the percentage of elongation from 7.8 to 5.6. The grains were more uniformly distributed with addition of modifiers, and refiners further reduced the nucleation number of eutectic grains. The wear study demonstrated that the wear resistance is more in the Al–Si-Cu-Sr sample due to the increased level of hardness. The combination of multidirectional forging techniques with judicious incorporation of refiners and modifiers engenders a synergistic enhancement of microstructural integrity, hardness profiles, and wear-resistant properties in hypereutectic Al-20Si alloys. © 2024 Canadian Institute of Mining, Metallurgy and Petroleum.
Experimental and computational investigation of solid suspension and gas dispersion in a stirred vessel
(American Institute of Physics Inc., 2022) Ali, A.A.; Kumar, B.; Madana, V.S.T.
Hydrodynamics and residence time distribution (RTD) of fluid elements are key parameters to characterize the performance of stirred vessel. They are governed by geometric and operating parameters of the stirred vessel (SV). In the present work, the performance of the stirred vessel is studied using computational fluid dynamics (CFD) with realizable k-ϵ turbulence model. The multiple reference frame and sliding mesh approach are used for impeller motion. The solid-liquid flow and associated solid suspension characteristics are predicted using the two-fluid model (Euler-Granular). The performance of the stirred vessel is characterized by analyzing predicted velocity magnitude, solid concentration (suspension quality), and solid sedimentation. This is compared with the stirred vessel with draft tube baffle configuration (three inner baffles and six outer baffles). The recirculatory flow in draft tube SV helps to achieve uniform suspension and less sedimentation. Further, CFD simulations are carried out in Lagrangian way to analyze chaotic mixing among fluid elements. This is qualitatively analyzed using Poincaré map and quantitatively evaluated using Shannon entropy. The extent of chaotic mixing in draft tube SV is found to be high. The performance of the stirred vessel is further investigated through stimulus-response tracer techniques (RTD) to detect design flaws such as bypass and dead zones. This is analyzed for a wide range of operating parameters and identified optimum conditions (flow rate, impeller speed) for the operation of SV. The four different outlet pipe locations are chosen in SV. The bypass and dead volume are analyzed accordingly, and an optimum outlet pipe location is found. To reduce the extent of non-ideal parameters, three different gas source locations are considered and gases are dispersed in the form of bubbles. The gas dispersion at optimum gas injection point is found to reduce non-ideal parameters and improve the design of stirred vessel. © 2022 Author(s).
Magnetic behavior of polymorph composite nickel titanate nanofibers
(Royal Society of Chemistry, 2021) Kumar, B.; Dhanasekhar, C.; Anandhan, S.; Kalpathy, S.K.
Polymorph (spinel/ilmenite) composite nanofibers of nickel titanate (NTO) were prepared by a sol-gel assisted electrospinning process followed by pyrolysis using the styrene-acrylonitrile copolymer as a precursor at three different pyrolysis soaking temperatures (i.e. T= 773, 973, and 1173 K). The magnetic behavior of these composite NTO nanofibers was studied under isothermal and non-isothermal conditions in the temperature range of 20-300 K. The magnetic parameters such as coercivity (Hc), remanence (Mr), and saturation magnetisation (Ms) were found to be strongly dependent onT. The highestHcandMrwere observed for NTO nanofibers developed at 973 K, which have a mosaic structured morphology with spinel and ilmenite NTO crystallite sizes of ~39 nm and ~24 nm, respectively. On the other hand, the highestMsand switching field distribution were observed for mosaic structured NTO nanofibers having smaller crystallites (~13 nm and 24 nm for spinel and ilmenite NTO, respectively, with high inter-particle distance and high porosity) developed at 773 K, which are also rich in spinel NTO content. The correlation between the variation in magnetic behavior and structural/morphological features of NTO nanofibers is useful for NTO-based soft magnetic and multiferroic applications. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021.
Microwave-Assisted Extraction of Wax from Oily Sludge: An Experimental Study and its Process Variables Optimization Using Response Surface Methodology
(2015) Kumar, B.; Raj Mohan, Balakrishnan
The wax present in petroleum sludge, generated by refineries and at crude production sites, consists of paraffin hydrocarbons (C18 C36) known as paraffin wax and naphthenic hydrocarbons (C30 C60). The present study is aimed at the recovery of wax from petroleum oily sludge by microwave-assisted solvent extraction using a Toluene/MEK mixture and subsequently de-crystallizing the wax. The process variables affecting the microwave-assisted solvent extraction are optimized for recovery of wax. The simultaneous effects of process variables such as irradiation time (2 10 minutes), solvent to sludge ratio (40 80 wt%), reactant volume (100 300 ml), and microwave power (80 400 W) on the recovery of wax were evaluated. A central composite design and response surface methodology were used for the optimization of the extraction process. Based on the central composite design, quadratic models were developed to correlate the extraction process variables with the responses and the models were analyzed using appropriate statistical methods for analysis of variance. Optimization of process variables shows the maximum recovery of wax was about 79.57% at 300 ml of reactant volume with microwave power output of 400 W at 7.6 minutes of retention time with 56.56% of Toluene/MEK to sludge ratio. 2015, Taylor & Francis Group, LLC.
Microwave-Assisted Extraction of Wax from Oily Sludge: An Experimental Study and its Process Variables Optimization Using Response Surface Methodology
(Bellwether Publishing, Ltd., 2015) Kumar, B.; Raj Mohan, B.
The wax present in petroleum sludge, generated by refineries and at crude production sites, consists of paraffin hydrocarbons (C18–C36) known as paraffin wax and naphthenic hydrocarbons (C30–C60). The present study is aimed at the recovery of wax from petroleum oily sludge by microwave-assisted solvent extraction using a Toluene/MEK mixture and subsequently de-crystallizing the wax. The process variables affecting the microwave-assisted solvent extraction are optimized for recovery of wax. The simultaneous effects of process variables such as irradiation time (2–10 minutes), solvent to sludge ratio (40–80 wt%), reactant volume (100–300 ml), and microwave power (80–400 W) on the recovery of wax were evaluated. A central composite design and response surface methodology were used for the optimization of the extraction process. Based on the central composite design, quadratic models were developed to correlate the extraction process variables with the responses and the models were analyzed using appropriate statistical methods for analysis of variance. Optimization of process variables shows the maximum recovery of wax was about 79.57% at 300 ml of reactant volume with microwave power output of 400 W at 7.6 minutes of retention time with 56.56% of Toluene/MEK to sludge ratio. © 2015, Taylor & Francis Group, LLC.
Multi-criteria optimization of fly ash and iron ore tailing based concretes subjected to elevated temperatures
(Associated Cement Companies Ltd., 2019) Yaragal, S.C.; Babu Narayan, K.S.; Kumar, B.; Francis, J.G.
Due to the rapid increase in concrete utilization all over the world, there is increased consumption of Ordinary Portland Cement (OPC), natural fine aggregate (NFA), and natural coarse aggregates. Increased use of OPC, is posing a serious threat due to excess CO2 emissions, and its production is highly energy intensive. On the other hand, extraction and processing stone-based fine and coarse aggregates too, is energy intensive, and the virgin resources are fast depleting. Therefore, for sustainable development, efforts are on all over the world to look for alternative materials in place of conventional ones. In this study, it is attempted to partly replace OPC with fly ash (FA) and partly replace NFA by iron ore tailings (IOT) in concretes. The performance of such concretes at ambient and elevated temperatures is also presented. Full factorial design of experiments was adopted with two control factors under three levels of replacement, i.e., FA (0, 15, and 30% by weight of OPC) and IOT (0, 50, and 100% by volume of NFA). Total nine concrete mixes were prepared and tested for their compressive strengths at room temperature, and residual compressive strengths when subjected to various levels of elevated temperatures (200, 400, 600, and 800°C), and cost of these concretes has also been analyzed. Further, three traditional multi–criteria optimization methods, i.e., grey relational analysis (GRA), technique for order of preference by similarity to ideal solution (TOPSIS), and desirability function approach (DFA) were used to optimize concrete mixes. Results showed that TOPSIS based optimization method is more significant when compared to other two methods. Further, FA-based concrete mixes showed improved performance under multi-criteria optimization. © 2019, Associated Cement Companies Ltd. All rights reserved.
Numerical and experimental studies on sustainable alkali activated concretes at elevated temperatures
(Emerald Publishing, 2023) Yaragal, S.C.; Kumar, B.; Abhinav, M.U.
Purpose: To reduce environmental impact caused by excessive use of ordinary Portland cement (OPC) and to mitigate scarcity of base materials such as natural coarse aggregate (NCA), industrial by-products can be carefully used as alternatives to OPC and NCA, in production of concrete. This paper aims to describe the performance of using ground granulated blast furnace slag (GGBS), fly ash (FA) as a complete replacement to OPC and ferrochrome slag (FCS) as replacement to NCA in production of novel FCS based alkali activated slag/fly ash concretes (AASFC) and evaluate their performance at elevated temperatures. Design/methodology/approach: Two control factors with three levels each i.e. FA (0, 25 and 50 per cent by weight) and FCS (0, 50 and 100 per cent by volume) as a GGBS and NCA replacement, respectively, were adopted in AASFC mixtures. Further, AASFC mixture specimens were subjected to different levels of elevated temperature, i.e. 200°C, 400°C, 600°C and 800°C. Compressive strength and residual compressive strength were considered as responses. Three different optimization techniques i.e. gray relational analysis, technique for order preference by similarity to ideal solution and Desirability function approach were used to optimize AASFC mixtures subjected to elevated temperatures. Findings: As FA replacement increases in FCS based AASFC mixtures, workability increases and compressive strength decreases. The introduction of FCS as replacement to NCA in AASFC mixture did not show any significant change in compressive strength under ambient condition. AASFC produced with 75 per cent GGBS, 25 per cent FA and 100 per cent FCS was found to have excellent elevated temperature enduring properties among all other AASFC mixtures studied. Originality/value: Although several studies are available on using GGBS, FA and FCS in production of OPC-based concretes, present study reports the performance of novel FCS based AASFC mixtures subjected to elevated temperatures. Further, GGBS, FA and FCS used in the present investigation significantly reduces CO2 emission and environmental degradation associated with OPC production and NCA extraction, respectively. © 2019, Emerald Publishing Limited.
An optimization study of microwave assisted extraction of oil from oily sludge using response surface methodology
(2014) Kumar, B.; Raj Mohan, Balakrishnan
Petroleum oily sludge, a hazardous waste, generated by the refineries and at the production sites in huge quantities comprises of a mixture of petroleum hydrocarbons, asphaltenes, long chain paraffinic wax, waste water, sediments and metals. The present study is aimed to recover oil from the petroleum oily sludge using n-heptane as the solvent in microwave assisted solvent extraction process and to optimize the process variables for the recovery of oil from the oily sludge. The simultaneous effects of process variables such as irradiation time (2 - 10 minutes), solvent to sludge ratio (40 80 wt %), reactant volume (100 300 ml) and microwave power (80 400 W) on the recovery of oil were evaluated. A central composite design (CCD) and response surface methodology (RSM) were used for the optimization of the extraction process. Based on the CCD, quadratic model was developed to correlate the extraction process variables with the responses and the model was analysed using appropriate statistical method (ANOVA). Optimization of process variables shows that the maximum recovery of oil was about 88.6% at 100 ml of reactant volume with microwave power output of 351 W at 6.5 minutes of irradiation time with 58.99% of nheptane to sludge ratio. 2014 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
Organoclay enabled nanofiber formation from a polyolefin elastomer
(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2018) Kumar, B.; Prakrthi, A.N.; Senthil, T.; Bhat, K.; Anandhan, S.
The solution electrospinning of polyolefins has not been deeply studied mainly due to the difficulty in dissolving these polymers in appropriate solvents. In this study, composite nanofibers of organically modified montmorillonite/ethylene-octene random copolymer were produced for the first time with a mixture of cyclohexane and xylene as a solvent by solution electrospinning. Montmorillonite was used as an additive to increase the electrical charge density of the polymer solution. The influence of solution and process parameters on the electrospun ethylene-octene copolymer fibers' morphology and diameter was investigated using the design of experiment. Multiple regression analysis was used for the optimization of the electrospinning parameters. Ultrafine fibers, with diameters in the range of 150–350 nm were obtained; these nanofibers exhibited an excellent hydrophobicity over a period of 10 min as revealed by contact angle measurements. © 2016 Wiley Periodicals, Inc.
Performance evaluation of cement mortar compositions at elevated temperatures
(Associated Cement Companies Ltd., 2019) Yaragal, S.C.; Vivek, S.; Kumar, B.
Natural river sand is becoming scarce day by day due to rapid growth in construction sector. There is need for alternatives to be used in place of river sand. The performance of alternatives to river sand at elevated temperatures is also important in the likely event of fire accidents. In this study, the effect of elevated temperatures on the compressive strength of mortars containing Crushed Rock Fines (CRF) and Lateritic Sand (LS) is investigated. Cement mortar cubes were cast for varied proportion of lateritic soil and quarry dust as fine aggregate. Lateritic content was varied from 25%-100%, and 50% quarry dust was adopted. After 28 days of water curing, specimens were exposed to temperatures of 200, 400, 600, and 800°C. At room temperature, the compressive strength decreases with increase in level of lateritic fine aggregate. The lateritic mortar mixes (50, 75, and 100%) have exhibited superior elevated temperature endurance characteristics at 400, 600, and 800°C when compared to control mix. Even the 25% laterized mortar has performed equally well as that of control mix. At elevated temperatures, CRF blended mix has performed very poorly. Mortar containing lateritic sand has potential for utilization in buildings and other structures, for better fire endurance in the likely event of fire accidents. © 2019 Associated Cement Companies Ltd.. All rights reserved.
Phonon dynamics with collective spin excitations and orbital ordering in quasi-two-dimensional La1.4Sr1.6Mn2 O7
(American Physical Society, 2025) Mekap, S.; Kumar, B.; Ananthram, K.S.; Tarafder, K.; Ghosh, S.; Roy, A.
This paper discusses the coupling between spin-wave-mediated magnetic interactions and lattice degrees of freedom in bilayer La1.4Sr1.6Mn2O7 (BL-LSMO-0.3). The thermal evolution of the Raman shift, as obtained from micro-Raman spectroscopic measurements over a wide temperature range, reveals the evolution of phonon dynamics while the system undergoes a balance between double and superexchange spin-spin interactions through spin-wave modulation in different magnetic phases. The evolution of relative magnetoelastic coupling strengths for nearest-neighbor ferromagnetic and next-nearest-neighbor antiferromagnetic superexchange interactions in the high-temperature canted antiferromagnetic phases are estimated. We have also demonstrated the existence of orbital ordering and its correlation with spin-phonon dynamics in the canted antiferromagnetic phases of BL-LSMO-0.3 from the detailed analysis of the high-wave-number orbiton-related phonon modes. Our study further reveals the absence of charge ordering in the compound. The complex coupling of lattice distortion, orbital ordering, the nearest- and next-nearest-neighbor spin-spin interactions in determining the canted spin states of the system is discussed. © 2025 American Physical Society.
Polymer Nanocomposites for Food Packaging Applications
(CRC Press, 2016) George, G.; Kumar, B.; Srinivasan, A.
Polymers are widely used in packaging of food, chemicals, medicines, industrial components, agriculture, and household items as listed in Table 26.1. Polymer consumption has an average growth rate of 5% and it will touch a gure of 227 million metric tons in 2015. Criteria for selection of a particular polymer for packaging is its biodegradability, migration of hazardous compounds, barrier properties, processability, strength, and inertness. Polymers are made to order in a variety of fashions using additives, functionalization, crosslinking, and so on for a particular application. A successful packaging material should be able to maintain the quality of the packed commodities to meet the customers’ expectation as it moves from manufacturer to customer. © 2017 by Taylor and Francis Group, LLC.
Polymorph nickel titanate nanofibers as bifunctional electrocatalysts towards hydrogen and oxygen evolution reactions
(Royal Society of Chemistry, 2019) Kumar, B.; Tarafder, K.; Shetty, A.R.; Hegde, A.C.; Gudla, V.C.; Ambat, R.; Kalpathy, S.K.; Anandhan, S.
Producing pure H2 and O2 to sustain the renewable energy sources with minimal environmental damage is a key objective of photo/electrochemical water-splitting research. Metallic Ni-based electrocatalysts are expensive and eco-hazardous. This has rendered the replacement or reduction of Ni content in Ni-based electrocatalysts a decisive criterion in the development of bifunctional electrocatalytic materials. In the current study, spinel/ilmenite composite nickel titanate (NTO) nanofibers were synthesised using sol-gel assisted electrospinning followed by pyrolysis at different soaking temperatures (viz., 773, 973, and 1173 K). The presence of a defective spinel NTO phase (SNTO) distributed uniformly along the nanofibers was confirmed by X-ray photoelectron and Raman spectroscopy. The electron micrographs revealed the morphological change of NTO nanofibers from a mosaic to bamboo structure with an increase in pyrolysis soaking temperature. The electrocatalytic activity of NTO nanofibers obtained at different pyrolysis soaking temperatures for alkaline water-splitting was studied. The highly defective SNTO manifests properties similar to metallic Ni and favours H2 evolution through the hydrogen evolution reaction (HER) by adsorbing more H+ ions on active sites. In contrast, the ilmenite NTO favours O2 discharge. These results are explained based on the morphology of the NTO nanofibers. The mosaic structure which has higher porosity and greater SNTO content shows excellent HER performance. In contrast, the large bamboo structured NTO nanofibers which have lesser porosity and SNTO content cage the bigger (OH)ads ions at their catalytic sites to facilitate OER performance. 2019 © The Royal Society of Chemistry.
Seismic base isolation for structures using river sand
(2016) Patil, S.J.; Reddy, G.R.; Shivshankar, R.; Babu, R.; Jayalekshmi, B.R.; Kumar, B.
Generally seismic isolation is achieved by supporting the structure on laminated rubber bearings, friction pendulum bearings, roller bearings etc. Very little work has been performed using soil as a base isolation media. Experiments and analytical work has been performed on a structural model with isolated footing and found encouraging results. Details of this work are presented in this paper. 2016 Techno-Press, Ltd.
Seismic base isolation for structures using river sand
(Techno Press technop2@chollian.net, 2016) Patil, S.J.; Reddy, G.R.; Shivshankar, R.; Ramesh Babu, R.; Jayalekshmi, B.R.; Kumar, B.
Generally seismic isolation is achieved by supporting the structure on laminated rubber bearings, friction pendulum bearings, roller bearings etc. Very little work has been performed using soil as a base isolation media. Experiments and analytical work has been performed on a structural model with isolated footing and found encouraging results. Details of this work are presented in this paper. © 2016 Techno-Press, Ltd.