Krishnan Group
Publications
Peer-reviewed Publications
82) (Cover) S. Bhandari, R. Ramanathan, and S. Krishnan, Electron Transfer and Oxygen Reduction Kinetics of a Beef Sarcoplasm Film on a Polyion-Coated Electrode, 2025, ACS Electrochemistry, Oct. 2025, [PDF].
81) (Cover) S. Bhandari, S. A. Devage, R. Kumar, R. Ramanathan, and S. Krishnan, Electroanalysis of Meat Discoloration: Beef Sarcoplasm Extract with Storage Time, Analyst, The Royal Society of Chemistry,2025, 150, 3289 - 3297. [PDF]
80) (Cover) S. Bhandari, S. A. Devage, R. Kumar, R. Ramanathan, and S. Krishnan, Electrochemical Measurement of Freeze-Thaw Cycle Impact on Sarcoplasmic Oxidation in Beef, ACS Measurement Science Au,2025, 5, 3, 277–286. [PDF]
79) S. Bhandari, M. Dixon, C. Walgama, R. Nerimetla, and S. Krishnan, Linking Nanoscale Film Properties to Electrochemical Response in Cytochrome P450 Membrane Enzyme Films, ACS Measurement Science Au, 2025, [PDF].
78) G. Premaratne, S. Bhandari, C. Walgama, B.V. Chikkaveeraiah, A. Jin, and S. Krishnan, Size-Dependent Electrochemical and Morphological Properties of Magnetite Nanoparticles Adsorbed on Electrodes, ACS Measurement Science Au,2025, 5, 3, 325–331. [PDF]
77) V. Chandra, J. Garland, R. Rai, D. Zhou, C. Walgama, S. Krishnan, A. T. Long, T. Liu, L. Adhikari, and D. M. Benbrook, Mortalin and PINK1/Parkin‐Mediated Mitophagy Represent Ovarian Cancer‐Selective Targets for Drug Development, Advanced Science, 2025, http://doi.org/10.1002/advs.202505592
76) A. Sharma, R. Li, S. Bhandari, S. P. Suman, S. Krishnan, M. Pfeiffer, G. Mafi, and R. Ramanathan, Protein structure influences redox stability, oxygen affinity, and heat-induced denaturation properties of bovine myoglobin, hemoglobin, and cytochrome c, ACS Food Science & Technology, 2025, https://doi.org/10.1021/acsfoodscitech.5c00391.
75) S. B. K. Dias, S. Bhandari, S. A. Devage, J. A. Avery, R. Kumar, R. Ramanathan, and S. Krishnan, Discovery of Electrochemical Indicators Upon Sarcoplasmic Meat Discoloration, J. Am. Chem. Soc., 2024,146, 30728–30732. [PDF]
74) (Cover) Z.Syed, S.Samaraweera, Z. Wang, J. K. Schrader, C. Scott, J. Schut, D. J. Smith, J. D. Ramsey, and S. Krishnan, Colorimetric Hybridization Sensor for DNA Mimic of a SARS-CoV-2 RNA Marker: Direct and Inverse Bioanalysis, ACS Measurement Science Au, 2024, 4(6), 689–694. [PDF]
73) (Cover) Z. Syed, S. Samaraweera, Z. Wang, and S. Krishnan, Colorimetric Nano-Biosensor for Low-Resource Settings: Insulin as a Model Biomarker, Sensors & Diagnostics, The Royal Society of Chemistry, 2024, 3, 1659–1671. [PDF]
72) (Cover) G. Premaratne, J. Niroula, T. Moulton, and S. Krishnan, Nano-bio-electrocatalysis using Human Liver Microsomes and Cytochrome P450 Bactosomes: Pyrenyl-Nanocarbon Electrodes, ACS Applied Bio Materials, 2024,7(4), 2197–2204. [PDF]
71) Z. Wang, Z. Syed, Z. H. Al Mubarak, L. Lehoczky, C. Rodenbaugh, R. A. Bunce, and S. Krishnan, Integrating Colorimetry with Surface Sensitive Transducers: Advancing Molecular Diagnostics in Biofluids, Sensors and Actuators B: Chemical, 2024, 419, 136361. [PDF]
70) P. K. Rahul, Shekher Kummari, and S. Krishnan, Chapter 5, Signal Amplification Strategies for Biosensing of Clinically Important Analytes, Book Title: Biosensors for Personalized Healthcare, ISBN: 978-981-97-5472-4, Springer Nature Publisher, 2024. [PDF]
69) M. A. Scott, M. L. Denzer, R. Kumar, G. G. Mafi, M. Pfeiffer, S. Krishnan, and R. Ramanathan, Effects of Light and Oxygen Conditions on Nonenzymatic Metmyoglobin Reduction In Vitro, Meat and Muscle Biology, 2023, 7(1):16760, 1–6.
68) S. Krishnan, and Z. Syed, Colorimetric Visual Sensors for Point-of-needs Testing, Sensors and Actuators Reports, 2022, 4, 100078. [PDF]
67) J. Niroula, G. Premaratne, and S. Krishnan, Lab-on-Paper Aptasensor for Label-free Picomolar Detection of a Pancreatic Hormone in Serum, Biosensors and Bioelectronics: X, 2022, 10, 100114. [PDF]
66) Z. H. Al Mubarak,† G. Premaratne,† A. C. Dharmaratne, F. Mohammadparast, M. Andiappan, and S. Krishnan, Plasmonic Nucleotide Hybridization Chip for Attomolar Detection: Localized Gold and Tagged Core/Shell Nanomaterials, Lab on a Chip, 2020, 20, 717-721. [PDF] († These authors contributed equally)
65) S. Krishnan, Electrochemical Sensors for Large and Small Molecules in Biofluids, Journal of The Electrochemical Society, 2020, 167, 167505. [PDF]
64) E. Vargas, E. Povedano, S. Krishnan, H. Teymourian, F. Tehrani, S. Campuzano, E. Dassau, and J. Wang, Simultaneous Cortisol/Insulin Microchip Detection using Dual Enzyme Tagging, Biosensors and Bioelectronics, 2020, 167, 112512.[PDF]
63) J. R. Sempionatto, I. Jeerapan, S. Krishnan, and J. Wang, Wearable Chemical Sensors: Emerging Systems for On-body Analytical Chemistry, Analytical Chemistry, 2020, 92, 1, 378-396.[PDF]
62) S. Krishnan, Bioelectrodes for Evaluating Molecular Therapeutic and Toxicity Properties, Current Opinion in Electrochemistry, 2020, 19, 20-26. https://doi.org/10.1016/j.coelec.2019.09.004
61) A. Walker, C. Walgama, R. Nerimetla, S. H. Alavi, E. Echeverria, S. P. Harimkar, D. N. McIlroy, and S. Krishnan, Roughened Graphite Biointerfaced with Human Liver Microsomes: Surface and Electrochemical Characterizations, Colloids and Surfaces B: Biointerfaces,2020, 189, 110790. [Link]
60) A. C. Dharmaratne, J. T. Moulton, J. Niroula, C. Walgama, S. Mazumder, S. Mohanty, and S. Krishnan, Pyrenyl Carbon Nanotubes for Covalent Bilirubin Oxidase Biocathode Design: Should the Nanotubes be Carboxylated? Electroanalysis, 2020, https://doi.org/10.1002/elan.201900564.
59) G. Premaratne, A. C. Dharmaratne, Z. H. Al Mubarak, F. Mohammadparast, M. Andiappan, and S. Krishnan, Multiplexed Surface Plasmon Imaging of Serum Biomolecules: Fe3O4@Au Core/shell Nanoparticles with Plasmonic Simulation Insights, Sensors and Actuators B: Chemical, 2019, 299,126956. https://doi.org/10.1016/j.snb.2019.126956
58) S. Krishnan, and K. Y. Goud, Magnetic Particle Bioconjugates: A Versatile Sensor Approach, Magnetochemistry, 2019, 5(4), 64. https://doi.org/10.3390/magnetochemistry5040064
57) C. Walgama, A. Pathiranage, M. Akinwale, R. Montealegre, J. Niroula, E. Echeverria, D. N. McIlroy, T. A. Harriman, D. A. Lucca, and S. Krishnan, Buckypaper-Bilirubin Oxidase Biointerface for Electrocatalytic Applications: Buckypaper Thickness,ACS Applied Bio Materials,2019, 2, 5, 2229–2236. [PDF]
56) G. Premaratne,† J. Niroula,† M. K. Patel, W. Zhong, S. L. Suib, A. K. Kalkan, and S. Krishnan, Electrochemical and Surface Plasmon Correlation of Serum Autoantibody Immunoassay with Binding Insights: Graphenyl Surface vs. Mercapto-Monolayer Surface, Analytical Chemistry, 2018,90, 12456–12463. († These authors contributed equally) [PDF]
55) S. Krishnan, M. Frazis, G. Premaratne, J. Niroula, E. Echeverria, and D. N. McIlroy, Pyrenyl–Carbon Nanostructures for Scalable Enzyme Electrocatalysis and Biological Fuel Cells, Analyst,2018, 143, 2876–2882. [PDF]
54) R. Nerimetla, G. Premaratne, H. Liu, and S. Krishnan, Improved Electrocatalytic Metabolite Production and Drug Biosensing by Human Liver Microsomes Immobilized on Amine-Functionalized Magnetic Nanoparticles, ElectrochimicaActa, 2018, 280, 101–107. [PDF]
53) V. Singh and S. Krishnan, Electrochemical and Surface Plasmon Insulin Assays on Clinical Samples, Analyst (Critical Review),2018, 143, 1544–1555. [PDF]
52) R. Nerimetla, C. Walgama, V. Singh, S. Hartson, and S. Krishnan, Mechanistic Insights into Voltage-Driven Biocatalysis of a Cytochrome P450 Bactosomal Film on a Self-assembled Monolayer, ACS Catalysis, 2017, 7, 3446–3453. [PDF]
51) G. Premaratne, S. Farias, and S. Krishnan, Pyrenyl Carbon Nanostructures for Ultrasensitive Measurements of Formaldehyde in Urine, Analytica Chimica Acta, 2017, 970, 23–29. [PDF]
50) G. Premaratne, Z. Al Mubarak, L. Senavirathna, L. Liu, and S. Krishnan, Measuring Ultra-low Levels of Nucleotide Biomarkers Using Quartz Crystal Microbalance and SPR Microarray Imaging Methods: A Comparative Analysis, Sensors & Actuators: B. Chemical, 2017, 253,368–375. [PDF]
49) V. Singh, R. Nerimetla, M. Yang, and S. Krishnan, Magnetite-Quantum Dot Immunoarray for Plasmon-coupled-Fluorescence Imaging of Blood Insulin and Glycated Hemoglobin, ACS Sensors, 2017, 2, 909–915. [PDF]
48) R. Nerimetla, S. Krishnan, S. Mazumder, S. Mohanty, G. G. Mafi, D. L. VanOverbeke, R. Ramanathan, Species-specificity in myoglobin oxygenation and reduction potential properties, Meat and Muscle Biology, 2017, 1, 1-7. [PDF]
47) (Invited) G. Premaratne, L. Coats, and S. Krishnan, NanoArmoring of Enzymes by Polymer-Functionalized Iron Oxide Nanoparticles. In C. Vijay Kumar, editor: NanoArmoring of Enzymes: Rational Design of Polymer-Wrapped Enzymes, Vol 590, MIE, UK: Academic Press, 2017, pp. 225-257.
46) J. Niroula, G. Premaratne, S. A. Shojaee, D. A. Lucca, and S.Krishnan, Combined Covalent and Noncovalent Carboxylation of Carbon Nanotubes for Sensitivity Enhancement of Clinical Immunosensors, Chem. Commun.2016, 52,13039-13042. [PDF]
45) V. Singh, C. Rodenbaugh, and S. Krishnan, Magnetic Optical Microarray Imager for Diagnosing Type of Diabetes in Clinical Blood Serum Samples, ACS Sensors2016, 1, 437-443. [PDF]
44) N. Lalaoui, N. Means, A. Le Goff, M. Holzinger, C. Walgama, S. Krishnan, and S. Cosnier, Enzymatic versus electrocatalytic oxidation of NADH at carbon-nanotube electrodes modified with glucose dehydrogenases. Application to bucky-paper-based glucose enzymatic fuel cells, ChemElectroChem 2016, 3, 2058-2062. [PDF]
43) G. Premaratne, R. Nerimetla, R. Matlock, L. Sunday, R. S. Hikkaduwa Koralege, J. D. Ramsey, and S. Krishnan, Stability, Scalability, and Reusability of a Volume Efficient Biocatalytic System Constructed on Magnetic Nanoparticles, Catal. Sci. Technol. 2016, 6,2361–2369. [PDF]
42) (Invited) C. Walgama, M. Gallman, and S. Krishnan, Single Drop Electroanalysis and Interfacial Interactions: Sensitivity versus Limit of Detection, Electroanalysis2016, 28, 2791-2796. (Special Issue:Professor Petr Zuman's 90th Birthday Issue). [PDF]
41) C. Walgama, Z. H. Al Mubarak, B. Zhang, M. Akinwale, A. Pathiranage, J. Deng, K. D. Berlin, D. M. Benbrook, and S. Krishnan, Label-free Real-time Microarray Imaging of Cancer Protein-Protein Interactions and Their Inhibition by Small Molecules, Anal. Chem. 2016,88, 3130–3135. [PDF]
40) S. Varghese, C. Walgama, M. Wilkins, S. Krishnan, and K. Kalkan, Surface-Charge-Enabled Photolytic Hydrogen Generation in V2O5·H2O/Au Nanoconjugates, MRS Advances, Available on CJO 2016, 1, Issue 46 (Energy and Environment), 3121-3126. doi:10.1557/adv.2016.273
39) L. C. Kasi Viswanath, J. Bernhardt, K. Gnanasekaran, C. Want, J. Frank, J. Faulkner, and S. Krishnan, Alkyl- and aryl-substituted Benzo[ghi]perylenetriimides: Synthesis, characterization and comparison of electrochemical and spectroscopic properties, Dyes and Pigments 2016, 134, 453-458. [PDF]
38) (Invited Book Chapter) S. Krishnan, and J. F. Rusling, Electrochemically Activated Catalytic Pathways of Human Metabolic Cytochrome P450s in Ultrathin Films, In: J. H. Zagal and F. Bedioui (eds.), Electrochemistry of N4 Macrocyclic Metal Complexes, 2nd Ed., Springer International Publishing, Switzerland, 2016, pp. 83-105, DOI: 10.1007/978-3-319-31332-0_2
37) Z. H. Al Mubarak, R. Ramesh, L. Liu, and S. Krishnan, Surface Plasmon Resonance Imaging of Gold-Small Molecule Interactions Is Influenced by Refractive Index and Chemical Structures, J. Colloid Interface Sci. 2015, 460, 209–213. [PDF]
36) R. Nerimetla, and S. Krishnan, Electrocatalysis by Subcellular Liver Fractions Bound to Carbon Nanostructures for Stereoselective Green Drug Metabolite Synthesis, Chem. Commun.2015, 51, 11681-11684. [PDF]
35) C. Walgama, R. Nerimetla, N. F. Materer, D. Schildkraut, J. F. Elman and S. Krishnan, A Simple Construction of Electrochemical Liver Microsomal Bioreactor for Rapid Drug Metabolism and Inhibition Assays,Anal. Chem. 2015, 87, 4712-4718. [PDF]
34) V. Singh, and S. Krishnan, Voltammetric Immunosensor Assembled on Carbon-Pyrenyl Nanostructures for Clinical Diagnosis of Type of Diabetes, Anal. Chem.2015, 87,2648-2654. [PDF]
33) C. Walgama, N. Means, N. F. Materer, and S. Krishnan, Edge-to-edge Interaction between Carbon Nanotube-Pyrene Complexes and Electrodes for Biosensing and Electrocatalytic Applications, Phys. Chem. Chem. Phys.2015,17, 4025-4028. [PDF]
32) K. S. Prasad, C. Walgama, and S. Krishnan, Enhanced Electroactivity and Substrate Affinity of Microperoxidase-11 Attached to Pyrene-linkers π-π Stacked on Carbon Nanostructure Electrodes, RSC Adv. 2015,5, 11845-11849. [PDF]
31) A. Singh, K. Teegardin, M. Kelly, K. S. Prasad, S. Krishnan, and J. D. Weaver, Facile Synthesis and Complete Characterization of Homoleptic and Heteroleptic Cyclometalated Iridium(III) Complexes for Photocatalysis, J. Organomet. Chem.2015, 776, 51-59. [PDF]
30) L. C. Kasi Viswanath, L. D. Shirtcliff, S. Krishnan, and K. D. Berlin, SubPc-ZnPorphyrin Conjugates - Synthesis, characterization and properties, Dyes Pigments2015, 112, 283-289. [PDF]
29) M. K. Patel, M. A. Ali, S. Krishnan, V. V. Agrawal, A. A. A. Al Kheraif, H. Fouad, Z. A. Ansari, S. G. Ansari, and B. D. Malhotra, A Label-Free Photoluminescence Genosensor Using Nanostructured Magnesium Oxide for Cholera Detection, Sci. Rep.2015, 5, 17384; doi: 10.1038/srep17384
28) R. Nerimetla, C. Walgama, R. Ramanathan, and S. Krishnan, Correlating the Electrochemical Kinetics of Myoglobin-films to pH Dependent Meat Color, Electroanalysis2014, 26, 675-678. [PDF]
27) L. C. Kasi Viswanath, L. D. Shirtcliff, S. Krishnan, N. V. Handa, and K. D. Berlin, Synthesis, photophysical and electrochemical properties of bay-axial perylene diimide–subphthalocyanine dyads, Tetrahedron Lett.2014, 55, 4199-4202. [PDF]
26) V. Singh, and S. Krishnan, Electrochemical Mass Sensor for Diagnosing Diabetes in Human Serum, Analyst 2014, 139, 724 – 728. [PDF]
25) C. Walgama, and S. Krishnan, Tuning the electrocatalytic efficiency of heme-protein films by controlled immobilization on pyrene-functionalized nanostructure electrodes, J. Electrochem. Soc. 2014, 161, H47-H52. [PDF]
24) S. Krishnan, and C. Walgama, Electrocatalytic Features of a Heme-Protein Attached to Polymer Functionalized Magnetic Nanoparticles, Anal. Chem.2013, 85, 11420−11426. [PDF]
23) (Invited Book Chapter) S. Krishnan* and J. F. Rusling, Thin Iron Heme Enzyme Films on Electrodes and Nanoparticles for Biocatalysis, Chapter 5, In: New and Future Developments in Catalysis, Elsevier Publishers, 2013, pp.125-147.
Publications prior to joining OSU
22) S. Krishnan and F. A. Armstrong, Order-of-Magnitude Enhancement of an Enzymatic Hydrogen-Air Fuel Cell based On Pyrenyl Carbon Nanostructures, Chem. Sci.2012, 3,1015-1023.
21) Bioanalysis Young Investigator: Sadagopan Krishnan, Bioanalysis, 2011, 3(9), 949-50. http://www.future-science.com/doi/pdf/10.4155/bio.11.89
20) S. Krishnan, V. Mani, D. Wasalathanthri, C. V. Kumar, and J. F. Rusling, Attomolar Detection of a Protein Biomarker in Serum by Surface Plasmon Resonance Using Superparamagnetic Particle Labels, Angew. Chem. Int. Ed.2011, 50, 1175 –1178.
19) S. Krishnan, D. Wasalathanthri, L. Zhao, J. B. Schenkman, and J. F. Rusling, Efficient Bioelectronic Actuation of The Natural Catalytic Pathway of Human Metabolic Cytochrome P450s, J. Am. Chem. Soc.2011, 133, 1459–1465.
18) S. Krishnan, J. B. Schenkman, and J. F. Rusling, Bioelectronic Delivery of Electrons to Cytochrome P450 Enzymes, J. Phys. Chem. B2011, 115, 8371–8380 (Cover, feature article).
17) S. Krishnan, A.Abeykoon, J. B. Schenkman, and J. F. Rusling, Control of Electrochemical and Ferryloxy Formation Kinetics of Cyt P450s in Polyion Films by Iron Heme Spin State and Secondary Structure, J. Am. Chem. Soc.2009, 131, 16215-16224.
16) S. Krishnan, B.Bajrami, V.Mani, S.Pan, and J.F. Rusling, Comparison of DNA- Reactive Metabolites from Nitrosamine and Styrene using Voltammetric DNA/Microsomes Sensors, Electroanalysis2009, 21, 1005-1013.
15) S. Krishnan, E. G. Hvastkovs, B. Bajrami, J. B. Schenkman, and J. F. Rusling, Human Cyt P450 Mediated Metabolic Toxicity of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) evaluated using Electrochemiluminescent Arrays, Mol. Biosyst.2009, 5, 163-169.
14) L. Zhao, S. Krishnan, Y. Zhang, J. B. Schenkman, and J. F. Rusling, Differences in Metabolite-mediated Toxicity of Tamoxifen in Rodent vs. Human Using Electrochemiluminescent Arrays and DNA/microsome Nanoreactors, Chem. Res. Toxicol. 2009, 22, 341–347.
13) S. Krishnan, E.G. Hvastkovs, B.Bajrami, D. Choudhary, J.B. Schenkman, and J.F. Rusling, Synergistic Metabolic Toxicity Screening Using Microsome/DNA Electrochemiluminescent Arrays and Nanoreactors, Anal.Chem.2008, 80, 5279–5285 (Cover Article).
12) B.Bajrami,S. Krishnan, and J.F. Rusling, Microsome biocolloids for rapid drug metabolism and inhibition assessment by LC-MS, Drug Metab.Lett.2008, 2, 158-162.
11) J. D. Fair, A. L. Bartelson, B. Bajrami, C. M. Cardillo, M. L. Dean, S. Krishnan, N. Sardesai, and T. A. Miller, Graduate Student Symposium Planning Committee Experiences, J. Chem. Ed.2008, 85, 1609.
10) S. Krishnan and J. F. Rusling, Evaluation of Liver Microsomes for Genotoxicity Sensors: Voltammetry of the Microsomes, Electrochem. Soc. Interface2007, 16 (4), 59-60.
9) S. Krishnan and J. F. Rusling, Thin film voltammetry of metabolic enzymes in Rat liver microsomes, Electrochem. Commun.2007, 9, 2359-2363.
8) S. Krishnan, E. G. Hvastkovs, B. Bajrami,I. Jansson, J. B. Schenkman, and J. F. Rusling, Genotoxicity screening For N-nitroso compounds by electrochemical and electrochemiluminescent detection of human enzyme-generated DNA damage, Chem.Commun.2007, 1713-1715.
7) E. G. Hvastkovs, M. So, S. Krishnan, B. Bajrami,M. Tarun,I. Jansson, J. B. Schenkman, and J. F. Rusling, Electrochemiluminescent Arrays for Cytochrome P450-activated Genotoxicity Screening. DNA Damage from Benzo[a]pyrene Metabolites, Anal. Chem.2007, 79, 1897-1906.
6) I. P. Bhowmick, S. Krishnan, and G. K. Jarori, Differential susceptibility of Plasmodium falciparum versus yeast and mammalian enolases to dissociation into active monomers, FEBS journal, 2007, 274, 1932-1945.
5) (Book Chapter) H. Vekaria, K.Sadagopan, J. Adamec, G.K. Jarori and C.R. Prabha, Thiol stress induces catalaseA in Streptomyces coelicolor(in: Communicating Current Research and Educational Topics and Trends in Applied Microbiology, Microbiology Book series, Formatex, Spain, 2007).
4) K. Sadagopan, A. S. Rekha, D. Ratna, and A. B. Samui, Synthesis and Characterization of Azo-based Methacrylate polymers with methoxy and nitro end groups for non-linear Optical applications, J. Appl. Polym. Sci. 2007, 104 (6), 3497-3504.
3) K. Sadagopan, S. Sawant, S. K. Kulshreshtha, and G. K. Jarori, Physical and Chemical Characterization of Enolase Immobilized polydiacetylene Langmuir Blodgett Film, Sensors and Actuators B, 2006,115, 526–533.
2) I. P. Bhowmick, K. Sadagopan, H. K. Vora, A. Sehgal, S. Sharma, and G. K. Jarori, Cloning, Over Expression, Purification and characterization of enolase from Plasmodium falciparum, European Journal of Biochemistry2004, 271, 4845-4854.
1) K. Sadagopan, D. Ratna, and A. B. Samui, Synthesis and Characterization of Liquid-Crystalline Epoxy and its Blend With conventional epoxy, J. Poly. Sci Part A: Poly. Chem.2003, 41, 3375-3383.
Patents
S. Krishnan, C. Walgama, and R. Nerimetla, Microsomal Bioreactor for Synthesis of Drug Metabolites, United States Patent Application, Pub. No.: US 2018/0044657, Pub. Date: Feb. 15, 2018.