Faculty Publications

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Publications by NITK Faculty

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Author: search.filters.author.Hegde, G.Has files: No

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    Photoalignment of nematic liquid crystal by thin films of bishydrazones derived from 3,4 dipropyloxythiophene
    (2010) Alla, R.A.; Hegde, G.; Ravi, K.; Vasudeva Adhikari, A.V.; Vishnumurthy, K.A.; Komitov, L.
    Photoalignment of nematic liquid crystals (LC) promoted by thin films of bishydrazone derived from 3, 4 dipropyloxythiophene is studied. Experimental results show that bishydrazone without methyl group in their structure is promoting planar alignment parallel to the polarization direction of the actinic light whereas the ones with methyl group in the structure are promoting planar alignment perpendicular to light polarization direction. © 2010 ITE and SID.
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    Investigation of the photoalignment effect of 1, 3, 4-oxadiazoles bearing 2-fluoro-4-methoxy phenyl moiety
    (2010) Alla, R.A.; Hegde, G.; Isloor, A.M.; Chandrakantha, B.; Shetty, P.; Komitov, L.
    A new series of 1,3,4-oxadiazole derivatives containing 2-fluoro-4-methoxy moiety were synthesized by refluxing mixture of acid hydrazide 3 with different aromatic carboxylic acid in phosphorous oxychloride. Photoalignment studies were performed on these materials indicating that the position of fluorine plays vital role in promoting planar alignment either parallel or perpendicular to the light polarization direction. © 2010 ITE and SID.
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    Recent developments in photoalignment technology: Alignment properties of a thiophene based bis-hydrazone derivative
    (2012) Hegde, G.; Srivastava, A.K.; Vasudeva Adhikari, A.V.; Vishnumurthy, K.A.; Mohd Yusoff, M.M.; Chigrinov, V.G.; Kwok, H.S.
    Liquid crystal photoalignment on bis-hydrazones derived from thiophene derivatives is reviewed. Proposed material shows excellent alignment properties which is highly promisable for future applications. This photoalignment is based on reorientation phenomena attributed to thiophenes.
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    Urban land cover classification using hyperspectral data
    (International Society for Photogrammetry and Remote Sensing, 2014) Hegde, G.; Mohammed Ahamed, J.M.; Hebbar, R.; Raj, U.
    Urban land cover classification using remote sensing data is quite challenging due to spectrally and spatially complex urban features. The present study describes the potential use of hyperspectral data for urban land cover classification and its comparison with multispectral data. EO-1 Hyperion data of October 05, 2012 covering parts of Bengaluru city was analyzed for land cover classification. The hyperspectral data was initially corrected for atmospheric effects using MODTRAN based FLAASH module and Minimum Noise Fraction (MNF) transformation was applied to reduce data dimensionality. The threshold Eigen value of 1.76 in VNIR region and 1.68 in the SWIR region was used for selection of 145 stable bands. Advanced per pixel classifiers viz., Spectral Angle Mapper (SAM) and Support Vector Machine (SVM) were used for general urban land cover classification. Accuracy assessment of the classified data revealed that SVM was quite superior (82.4 per cent) for urban land cover classification as compared to SAM (67.1 per cent). Selecting training samples using end members significantly improved the classification accuracy by 20.1 per cent in SVM. The land cover classification using multispectral LISS-III data using SVM showed lower accuracy mainly due to limitation of spectral resolution. The study indicated the requirement of additional narrow bands for achieving reasonable classification accuracy of urban land cover. Future research is focused on generating hyperspectral library for different urban features.
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    Design, fabrication and characterization of 5 μm ring resonator
    (Optica Publishing Group (formerly OSA), 2016) Kollia, V.R.; Yadunath, T.R.; Resmi, R.K.; Hegde, G.; Badrinarayana, T.; Das, P.P.; Srinivas, T.
    We present the design, simulation, fabrication and characterization of microring resonator on SOI platform. Proposed feature size device resonates at a wavelength of 1565.92 nm. The fabricated device has potential applications in communication and sensing. © OSA 2016.
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    Multiple Order and Broadband Optical Orbital Angular Momentum Source using a Single Photonic Crystal Device
    (Institute of Electrical and Electronics Engineers Inc., 2020) Yadunath, T.R.; Ravindran, R.; Hegde, G.; Das, P.P.; Srinivas, S.
    A promising optical integrated circuit device design for the generation of broadband, low order OAM modes with topological charges of +1 and +2 is successfully conceptualized using a combination of ring and point defect in thin photonic crystal slab structure with circular array of holes. © 2020 IEEE.
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    Ethyl 1-(2,4-dichlorobenzyl)-4-oxo-7-trifluoromethyl-1,4-dihydroquinoline- 3-carboxyl-ate
    (2012) Fun, H.-K.; Ooi, C.W.; Garudachari, B.; Isloor, A.M.; Hegde, G.
    In the title compound, C 20H 14Cl 2F 3NO 3, the trifluromethyl group is disordered over two sets of sites in a 0.784 (10):0.216 (10) ratio. The quinoline ring system is essentially planar with a maximum deviation of 0.058 (2) Å for the N atom and forms dihedral angles of 89.23 (11) and 8.13 (17)°, respectively with the mean planes of the benzene ring and the carboxylate group. In the crystal, pairs of weak C - H?O and C - H?F hydrogen bonds link molecules into centrosymmetric dimers. The crystal structure is further stabilized by weak ?-? [centroid-centroid distance = 3.624 (2) Å] interactions.
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    2-(8-Bromoimidazo[1,2-a]pyridin-2-yl)-N?-[(E)-4-diethylamino-2- hydroxybenzyl-idene]acetohydrazide dihydrate
    (2012) Fun, H.-K.; Loh, W.-S.; Shenvi, S.S.; Isloor, A.M.; Hegde, G.
    In the title compound, C 20H 22BrN 5O 2·2H 2O, the Schiff base mol-ecule exists in an E conformation with respect to the acyclic C=N bond. An S(6) ring motif is formed via an intra-molecular O - H?N hydrogen bond. The dihedral angle between the imidazo[1,2-a]pyridine system and the benzene ring is 84.62 (5)°. In the crystal, N - H?O, O - H?O, O - H?N, C - H?O and C - H?Br hydrogen bonds link the mol-ecules into a three-dimensional network. The crystal packing is further stabilized by C - H?? and ?-? inter-actions [centroid-centroid distance = 3.5365 (7) Å].
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    Synthesis, characterization and antimicrobial studies of some new quinoline incorporated benzimidazole derivatives
    (2012) Garudachari, B.; Satyanarayana, M.N.; Thippeswamy, B.; Shivakumar, C.K.; Shivananda, K.N.; Hegde, G.; Isloor, A.M.
    Two new series of quinoline incorporated benzimidazole derivatives (4a-i and 8a-f) were synthesized from substituted aniline and isatin through multi-step reaction. 6-substituted-4-carboxyquinolines (3a,b and 7) were synthesized by multi component one pot reactions (via Doebner reaction and Pfitzinger reaction respectively) and the targeted benzimidazole derivatives were obtained by the reaction of 6-substituted-4-carboxyquinolines (3a,b and 7) with substituted aromatic diamines in acidic media. All the newly synthesized compounds were characterized by IR, NMR mass spectral study and also by C, H, N analyses. The final compounds were screened for their in-vitro antibacterial and antifungal activity by well plate method (zone of inhibition). The results revealed that, compounds 4c, 4d, 8c and 8d showed significant antibacterial activity. The compound 8b was found to be potent antifungal agent. 4a, 8a and 8f showed moderate to good antimicrobial activity as compared to the standard drugs against all tested microbial strains. © 2012 Elsevier Masson SAS. All rights reserved.
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    Synthesis and biological evaluation of novel substituted 1,3,4-thiadiazole and 2,6-di aryl substituted imidazo [2,1-b] [1,3,4] thiadiazole derivatives
    (Elsevier Masson s.r.l., 2014) Chandrakantha, B.; Isloor, A.M.; Shetty, P.; Fun, H.-K.; Hegde, G.
    A new series of N-[5-(4-(alkyl/aryl)-3-nitro-phenyl)-[1,3,4-thiadiazol-2- yl]-2,2-dimethyl-propionamide 4 (a-l) and 6-(4-Methoxy-phenyl)-2-(4-alkyl/aryl)- 3-nitro-phenyl)-Imidazo [2,1-b] [1,3,4] thiadiazole 6 (a-l) were synthesized starting from 5-(4-Fluoro-3-nitro-phenyl)-[1,3,4] thiadiazole-2-ylamine. The synthesized compounds were characterized by IR, NMR, mass spectral and elemental analysis. All the compounds were tested for antibacterial and antifungal activities. The antimicrobial activities of the compounds were assessed by well plate method (zone of inhibition). Compounds 4a, 4c and 6e, 6g displayed appreciable activity at the concentration 0.5-1.0 mg/mL.© 2013 Elsevier Masson SAS. All rights reserved.