Journal Articles
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Item Study on the strength parameters of high volume fly ash concrete and geopolymer concrete(2011) Shetty, A.; Anand, V.R.; Hegde, P.Concrete has been the most preferred construction material. It is being increasingly used day by day all over the world due to its versatility, mould ability and high compressive strength. But the large-scale production of cement is causing environmental problems on one hand and the unrestricted depletion of natural resources on the other. So the issue of sustainable development in concrete construction is addressed in this paper through development of concrete mixes by replacing certain percentage of cement with fly ash. Trials on concrete mixes with replacement of 40%, 50%, 60% and 70% of cement with fly ash are carried out and the results depict that at the replacement level of 40% cement by fly ash, the required strength is achieved. It is also observed that the rate of early strength gain is retarded as the percentage replacement of cement increases. But in case of Geopolymer concrete (100% replacement of cement by fly ash) under a curing temperature around 600C and above, the strength gain rate is very high in initial stages. It is observed that design strength is achieved within 28 hours of oven curing. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Synthesis, Characterization, Thermal and Antimicrobial studies of N-substituted Sulfanilamide derivatives(2014) Lahtinen, M.; Kudva, J.; Hegde, P.; Bhat, K.; Kolehmainen, E.; Nonappa, N.; Venkatesh; Naral, D.Four sulfanilamide derivatives N-[4-(phenylsulfamoyl)phenyl]acetamide (1), 4-amino-N-phenylbenzenesulfonamide (2), N-[4-(phenylsulfamoyl)phenyl]benzamide (3) and N-{4-[(3-chlorophenyl)sulfamoyl]phenylbenzamide (4) were synthesized and characterized by Infra-Red (IR), Nuclear Magnetic Resonance (NMR) and UV-visible (UV-Vis) spectra. Also Liquid Chromatographic (LCMS) and High Resolution Mass Spectrometric (HRMS) methods were used. Crystal structures of 1-4 were determined by single crystal X-ray diffraction (XRD) and their conformational and hydrogen bond (HB) network properties were examined with survey of the literature data. Compounds 1 and 2 crystallize in the same orthorhombic Pbca symmetry with equivalent molecular conformation (tilted V-shape) but showed distinct packing and hydrogen bonding models. Compounds 3 and 4 crystallize in monoclinic and triclinic crystal systems, albeit exhibiting identical molecular conformation (L-shaped). Same donor acceptor pairs both on 3 and 4 result to different kind of HB network. Thermogravimetric (TG) and differential scanning calorimetric (DSC) methods were used to evaluate thermal properties of the substances. All sulfanilamide derivatives have melting points between195-227 C, initiation of thermal decomposition between 259-271 C and enthalpies of fusion ?HfusT = 38.96, 36.60, 46.23 and 44.81 kJ mol -1 were determined for 1-4, respectively. The derivatives were screened for their antibacterial and antifungal activities against various bacterial and fungal strains. It is observed that there is no significant antibacterial activity with the introduction of the benzene ring to CO-NH group or SO2-NH moiety, and none of the compounds exhibited antifungal activity. © 2013 Elsevier B.V. All rights reserved.Item Evaluation of implant properties, safety profile and clinical efficacy of patient-specific acrylic prosthesis in cranioplasty using 3D binderjet printed cranium model: A pilot study(Churchill Livingstone, 2021) Basu, B.; Bhaskar, N.; Barui, S.; Sharma, V.; Das, S.; Govindarajan, N.; Hegde, P.; Perikal, P.J.; Antharasanahalli Shivakumar, M.; Khanapure, K.; Jagannatha, A.There exists a significant demand to develop patient-specific prosthesis in reconstruction of cranial vaults after decompressive craniectomy. we report here, the outcomes of an unicentric pilot study on acrylic cranial prosthesis fabricated using a 3D printed cranium model with its clinically relevant mechanical properties. Methods: The semi-crystalline polymethyl methacrylate (PMMA) implants, shaped to the cranial defects of 3D printed cranium model, were implanted in 10 patients (mean age, 40.8 ± 14.8 years). A binderjet 3D printer was used to create patient-specific mould and PMMA was casted to fabricate prosthesis which was analyzed for microstructure and properties. Patients were followed up for allergy, infection and cosmesis for a period of 6 months. Results: As-cast PMMA flap exhibited hardness of 15.8 ± 0.24Hv, tensile strength of 30.7 ± 3.9 MPa and elastic modulus of 1.5 ± 0.1 GPa. 3D microstructure of the semi-crystalline acrylic implant revealed 2.5–15 µm spherical isolated pores. The mean area of the calvarial defect in craniectomy patients was 94.7 ± 17.4 cm2. We achieved a cranial index of symmetry (CIS -%) of 94.5 ± 3.9, while the average post-operative Glasgow outcome scale (GOS) score recorded was 4.2 ± 0.9. Conclusions: 3D printing based patient-specific design and fabrication of acrylic cranioplasty implant is safe and achieves acceptable cosmetic and clinical outcomes in patients with decompressive craniectomy. Our study ensured clinically acceptable structural and mechanical properties of implanted PMMA, suggesting that a low cost 3D printer based PMMA flap is an affordable option for cranioplasty in resource constrained settings. © 2021 Elsevier LtdItem Efficient Lubricity Improvers Derived from Methyl Oleate for Ultra Low Sulphur Diesel (ULSD)(Pleiades Publishing, 2022) Sruthi, H.; Udayakumar, D.U.; Hegde, P.; Manjunatha, M.G.; Nandakumar, V.Abstract: A new series of lubricity improvers for ultra-low sulphur diesel (ULSD) was synthesized starting from methyl oleate through simple chemical reactions. In the first step methyl oleate was epoxidized using formic acid and hydrogen peroxide mixture. Then the epoxide was subjected to esterification using different long chain (C4–C18 alkyl groups) organic acids to get the final diesters. The lubricating property of the newly synthesized diesters was studied by dosing them to ULSD at 300 ppm (wt/vol) concentration. Amongst them, diester LAMOSA derived from stearic acid showed the best lubrication enhancing property at 300 ppm dosage level. The SEM and EDS spectra of the HFRR (high frequency reciprocating rig) specimen also confirms the formation of metal-oxygen interaction supporting the friction reducing properties of LAMOSA. The study reveals that the newly synthesized methyl oleate derived diesters are promising materials as lubricity additives for ULSD. [Figure not available: see fulltext.] © 2022, Pleiades Publishing, Ltd.Item Transformation of refinery cracked naphtha stream into efficient lubricity improvers for ULSD(Springer, 2022) Sruthi, H.; Udayakumar, D.U.; Hegde, P.; Manjunatha, M.G.; Karthick, R.; Nandakumar, V.A new route for the conversion of refinery light cracked naphtha (LCN) stream into lubricity improvers for ultra-low sulphur diesel (ULSD) was developed through a simple chemical process involving olefin epoxidation and esterification reactions. Two different methods viz., H2O2/glacial acetic acid and m-chloroperbenzoic acid (m-CPBA), were found to be suitable for the epoxidation of LCN. The LCN epoxide was subjected to an esterification reaction via epoxide ring opening using different long chain (C4 - C18 alkyl groups) organic acids to get the hydroxy ester derivatives of LCN. The lubricating property of the newly synthesized hydroxy esters was studied by dosing them with ULSD at 300 and 150 ppm (wt/vol) concentrations. Amongst them, LCN hydroxy ester derived from stearic acid showed the best lubrication-enhancing property at both dosage levels. The scanning electron microscope (SEM) image and energy dispersive spectra (EDS) of the high-frequency reciprocating rig (HFRR) specimen support the lubricating action of the LCN esters through the formation of a protective layer between the metallic surfaces. The synergy of simple chemical processes and efficient lubricity action makes these LCN esters as promising materials for low-cost and scalable additives for ULSD. Graphical abstract: The olefin-rich light cracked naphtha obtained from the fluidized catalytic cracker unit of the oil refinery was converted into hydroxy esters through an epoxidation reaction followed by the esterification with different carboxylic acids. The hydroxy esters at low dosage levels (150/300 ppm) enhance the lubricating property of ultra-low sulfur diesel. [Figure not available: see fulltext.]. © 2022, Indian Academy of Sciences.Item Fatty acid, fatty alcohol and acrylate derivatives as friction depressive additives for ultra-low sulphur diesel(Elsevier Ltd, 2023) Sruthi, H.; Udayakumar, D.; Hegde, P.; Manjunatha, M.G.Herein we report the synthesis of some fatty acid, fatty alcohol and acrylate derivatives as friction depressive additives for ultra-low sulphur diesel (ULSD). The high frequency reciprocating rig (HFRR) was employed to measure the wear scar diameter (WSD) of the samples. The lubricating property of the newly synthesized samples [2a, (4a-c) and (5a-c)] was studied by dosing them to ULSD at 200 ppm (wt/vol) concentrations. Amongst them, ester derived from OLA/Polyol (4c) showed the best lubrication enhancing property (WSD 328 µm) at 200 ppm(wt/vol) dosage level. Interestingly, it maintains lubricity characteristics even at a lower blending concentration of 100 ppm with a WSD value (446 µm) lower than the than the accepted value (460 µm). Notably, additives containing polar functional groups and long non-polar carbon backbone exhibited significant lubricity properties with low WSD values. Moreover, it possesses long term antiwear stability when blended with the diesel fuel and do not alter or negatively influence the physical and chemical parameters of the diesel. The FESEM and EDS analysis revealed the formation of thin defensive layer of the additive between the moving metal surfaces supporting the friction reducing properties of the additives. © 2023Item Perspective analysis of assistive robots for elderly in India(Taylor and Francis Ltd., 2024) Hegde, P.; Gadag, A.; Sontakke, S.; Kumar, M.; Kholia, A.; Patel, J.; Khan, A.; Jahnavi, E.; Nabala, R.; Thotappa, D.Purpose: Assistive technology for elderly are advancing, and this study aimed to analyse the Indian perspective on utilising assistive robot technology for aiding elderly individuals. Materials and Methods: A population-based survey was undertaken to collect data from three perspectives: Relatives of the elderly, Healthcare professionals and Elderly individuals. The survey gathered 389 responses. The responses are statistically analysed, and data is visualised with different plots for better understanding. Results: It is observed that the older people rate with less conviction on the use of technology when compared to the relatives and healthcare professionals. Out of the three target groups, the elderly individuals had the most correlating attributes to purchasing the robot. Also, healthcare personnel, relatives, and older people gave 82%, 63% and 55% affirmatives to the question on purchasing the robot, respectively. And the cost of the robot is preferred to be under 6 lakh rupees. Conclusions: Though the younger generation has more orientation towards technology, older people are skeptical about handling computer gadgets or robots. However, there are significant expectations and concerns expressed by three target groups such as conversational, navigational, reminder features, security and malfunction concerns. © 2024 Informa UK Limited, trading as Taylor & Francis Group.