• Muhammad Thalhah Zainal High Speed Reacting Flow (HiREF) Laboratory, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia
  • Mohd Fairus Mohd Yasin High Speed Reacting Flow (HiREF) Laboratory, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia
  • Mazlan Abdul Wahid High Speed Reacting Flow (HiREF) Laboratory, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia




Carbon nanotube, flame synthesis, modeling


Synthesis of carbon nanotubes in flames has become highly attractive due to its rapid, inexpensive, and simple method of production. The study of flame synthesis of carbon nanotubes revolves around the control of flame and catalyst parameters to increase the synthesis efficiency and to produce high quality nanotubes. The control parameters include flame temperature, concentration of carbon source species, catalyst type, equivalence ratio, and fuel type. Carbon nanotubes which are produced with rapid growth rate and possess high degree of purity and alignment are often desired. The present study reviews various optimization techniques from the advanced studies of chemical vapour deposition which are applicable for the synthesis of nanotubes in flames. The water-assisted and catalyst free synthesis are seen as possible candidates to improve the growth rate, alignment, and purity of the synthesized nanotubes. The state-of-the-art of the flame synthesis modelling at particle and flame scales are reviewed. Based on the thorough review of the recent experimental findings related to the catalytic growth of nanotube, possible refinement of the existing particle scale model is discussed. The possibility of two-way coupling between the two scales in computational fluid dynamics may be a major contribution towards the optimization of the flame synthesis.


Iijima, S. 1991. Helical microtubules of graphitic carbon. Nature. 354 (6348): 56–58.

Wood, J. 2007. Putting the heat on nanotubes. Nano Today. 2 (6): 8.

Zakaria, M.R., H.M. Akil, M.H.A. Kudus, and S.S.M. Saleh. 2014. Enhancement of tensile and thermal properties of epoxy nanocomposites through chemical hybridization of carbon nanotubes and alumina. Compos. Part A Appl. Sci. Manuf. 66: 109–116.

Spitalsky, Z., D. Tasis, K. Papagelis, and C. Galiotis. 2010. Carbon nanotube–polymer composites: Chemistry, processing, mechanical and electrical properties. Prog. Polym. Sci. 35 (3): 357–401.

Hu, Z. and X. Lu. 2014. Carbon Nanotubes and Graphene, 2nd ed. Elsevier Ltd. 165–200.

Wang, A., Y. Cheng, H. Zhang, Y. Hou, Y. Wang, and J. Liu. 2014. Effect of Multi-Walled Carbon Nanotubes and Conducting Polymer on Capacitance of Mesoporous Carbon Electrode. J. Nanosci. Nanotechnol. 14 (9): 7015–7021.

Srivastava, A., A.K. Srivastava, and O.N. Srivastava. 2001. Curious aligned growth of carbon nanotubes under applied electric field. Carbon. 39 (2) 201–206.

Sealy, C. 2007. Carbon nanotubes offer a crack cure. Nano Today. 2 (6): 10.

Sandler, J.K., S. Pegel, M. Cadek, F. Gojny, M. van Es, J. Lohmar, W.J. Blau, K. Schulte, A.H. Windle, and M.S.P. Shaffle. 2004. A comparative study of melt spun polyamide-12 fibres reinforced with carbon nanotubes and nanofibres. Polymer. 45 (6): 2001–2015.

Coleman, J.N., U. Khan, W.J. Blau, and Y.K. Gun’ko. 2006. Small but strong: A review of the mechanical properties of carbon nanotube-polymer composites. Carbon. 44 (9): 1624–1652.

Sealy, C. 2013. Carbon nanotubes target tumors in two steps. Nano Today. 8 (6): 557.

Liu, Z., X. Sun, N. Nakayama-Ratchford, and H. Dai. 2007. Supramolecular chemistry on water-soluble carbon nanotubes for drug loading and delivery. ACS Nano. 1 (1): 50–56.

Kam, N.W.S., M. O’Connell, J.A. Wisdom, and H. Dai. 2005. Carbon nanotubes as multifunctional biological transporters and near-infrared agents for selective cancer cell destruction. Proc. Natl. Acad. Sci. U. S. A. 102 (33): 11600–11605.

Han, Z.J., A.E. Rider, C. Fisher, T. van der Laan, S. Kumar, I. Levchenko, and K. Ostrikov. 2014. Carbon Nanotubes and Graphene. 2nd ed. Elsevier Ltd. 279–312.

Eatemadi, A., H.D.H.K.M. Kouhi, N. Zarghami, A. Akbarzadeh, M. Abasi, Y. Hanifehpour, and S.W. Joo. 2014. Carbon nanotubes: properties, synthesis, purification, and medical applications. Nanoscale Res. Lett. 9 (393): 1–13.

Gore, J.P and A. Sane. 2011. Synthesis. Characterization, Applications. InTech. 121–146.

Merchan-Merchan, W., A. V. Saveliev, L. Kennedy, and W.C. Jimenez. 2010. Combustion synthesis of carbon nanotubes and related nanostructures. Prog. Energy Combust. Sci. 36 (6): 696–727.

Naha, S., S. Sen, A.K. De, and I.K. Puri. 2007. A detailed model for the flame synthesis of carbon nanotubes and nanofibers. Proc. Combust. Inst. 31 (2): 1821–1829.

Mittal, G., V. Dhand, K.Y. Rhee, H.J. Kim, and D.H. Jung. 2015. Carbon nanotubes synthesis using diffusion and premixed flame methods: a review. Carbon Lett. 16 (1:) 1–10.

Seah, C.M., S.P. Chai, and A.R. Mohamed. 2011. Synthesis of aligned carbon nanotubes. Carbon. 49 (14): 4613–4635.

Unrau, C.J., R.L. Axelbaum, P. Biswas, and P. Fraundorf. 2007. Synthesis of single-walled carbon nanotubes in oxy-fuel inverse diffusion flames with online diagnostics. Proc. Combust. Inst. 31: 1865–1872.

Nakazawa, S., T. Yokomori, and M. Mizomoto. 2005. Flame synthesis of carbon nanotubes in a wall stagnation flow. Chem. Phys. Lett. 403 (1-3): 158–162.

Woo, S.K., Y.T. Hong, and O.C. Kwon. 2009. Flame-synthesis limits and self-catalytic behavior of carbon nanotubes using a double-faced wall stagnation flow burner. Combust. Flame. 156 (10): 1983–1992.

Vander Wal, R.L., and L.J. Hall. 2002. Ferrocene as a precursor reagent for metal-catalyzed carbon nanotubes: Competing effects. Combust. Flame. 130 (1-2): 27–36.

Hou, S.S., D.H. Chung, and T.H. Lin. 2009. High-yield synthesis of carbon nano-onions in counterflow diffusion flames. Carbon. 47 (7): 938–947.

Hu, W.C., S.S. Hou, and T.H. Lin. 2014. Analysis on Controlling Factors for the Synthesis of Carbon Nanotubes and Nano-Onions in Counterflow Diffusion Flames. J. Nanosci. Nanotechnol. 14 (7): 5363–5369.

Hall, B., C. Zhuo, Y.A. Levendis, and H. Richter. 2011. Influence of the fuel structure on the flame synthesis of carbon nanomaterials. Carbon. 49 (11): 3412–3423.

Vander Wal, R.L., T.M. Ticich, and V.E. Curtis. 2000. Diffusion flame synthesis of single-walled carbon nanotubes. Chem. Phys. Lett. 323 (3-4): 217–223.

Vander Wal, R.L. and T.M. Ticich. 2001. Comparative Flame and Furnace Synthesis of Single-Walled Carbon Nanotubes. Chem. Phys. Lett. 336 (1-2): 24–32.

Unrau, C.J. and R.L. Axelbaum. 2010. Gas-phase synthesis of single-walled carbon nanotubes on catalysts producing high yield. Carbon 48 (5): 1418–1424.

Vander Wal, R.L. 2002. Flame synthesis of Ni-catalyzed nanofibers. Carbon. 40 (12): 2101–2107.

Gopinath, P. and J. Gore. 2007. Chemical kinetic considerations for postflame synthesis of carbon nanotubes in premixed flames using a support catalyst. Combust. Flame. 151 (3): 542–550.

Zhuo, C., B. Hall, H. Richter, and Y. Levendis. 2010. Synthesis of carbon nanotubes by sequential pyrolysis and combustion of polyethylene. Carbon. 48 (14): 4024–4034.

Vander Wal, R.L., L.J. Hall, and G.M. Berger. 2002. The chemistry of premixed flame synthesis of carbon nanotubes using supported catalysts. Proc. Combust. Inst. 29 (1): 1079–1085.

Xu, F., X. Liu, and S.D. Tse. 2006. Synthesis of carbon nanotubes on metal alloy substrates with voltage bias in methane inverse diffusion flames. Carbon. 44 (3): 570–577.

Arana, C.P., I.K. Puri, and S. Sen. 2005. Catalyst influence on the flame synthesis of aligned carbon nanotubes and nanofibers. Proc. Combust. Inst. 30 (2): 2553–2560.

Merchan-Merchan, W., A. V. Saveliev, and L.A. Kennedy. 2004. High-rate flame synthesis of vertically aligned carbon nanotubes using electric field control. Carbon. 42 (3): 599–608.

Merchan-Merchan, W., A. V. Saveliev, and L.A. Kennedy. 2006. Flame nanotube synthesis in moderate electric fields: From alignment and growth rate effects to structural variations and branching phenomena. Carbon. 44 (15): 3308–3314.

Memon, N.K., F. Xu, G. Sun, S.J.B. Dunham, B.H. Kear, and S.D. Tse. 2013. Flame synthesis of carbon nanotubes and few-layer graphene on metal-oxide spinel powders. Carbon. 63: 478–486.

Memon, N.K., Multiple Inverse-Diffusion Flame Synthesis of Carbon Nanomaterials, PhD Thesis, Rutgers State University of New Jersey, 2012.

Unrau, C.J., R.L. Axelbaum, and P. Fraundorf. 2010. Single-walled carbon nanotube formation on iron oxide catalysts in diffusion flames. J. Nanoparticle Res. 12 (6): 2125–2133.

Lee, G.W., J. Jurng, and J. Hwang. 2004. Formation of Ni-catalyzed multiwalled carbon nanotubes and nanofibers on a substrate using an ethylene inverse diffusion flame. Combust. Flame. 139 (1-2): 167–175.

Lee, G.J., J. Jurng, and J. Hwang. 2004. Synthesis of carbon nanotubes on a catalytic metal substrate by using an ethylene inverse diffusion flame. Carbon. 42 (3): 682–685.

Li, T.X., K. Kuwana, K. Saito, H. Zhang, and Z. Chen. 2009. Temperature and carbon source effects on methane-air flame synthesis of CNTs. Proc. Combust. Inst. 32 (2): 1855–1861.

Wen, J.Z., M. Celnik, H. Richter, M. Treska, J.B. Vander Sande, and M. Kraft. 2008. Modelling study of single walled carbon nanotube formation in a premixed flame. J. Mater. Chem. 18 (13): 1582.

Moisala, A., A.G. Nasibulin, D.P. Brown, H. Jiang, L. Khriachtchev, and E.I. Kauppinen. 2006. Single-walled carbon nanotube synthesis using ferrocene and iron pentacarbonyl in a laminar flow reactor. Chem. Eng. Sci. 61 (13): 4393–4402.

Singer, J.M. and J. Grumer. 1958. Carbon Formation in Very Rich Hydrocarbon-Air Flames-I. Studies of Chemical Content, Temperature, Ionization and Particulate Matter. Symp. Combust. 7 (1): 559–569.

Vander Wal, R.L. 2002. Fe-catalyzed single-walled carbon nanotube synthesis within a flame environment. Combust. Flame. 130 (1-2): 37–47.

Yuan, L., T. Li, and K. Saito. 2003. Growth mechanism of carbon nanotubes in methane diffusion flames. Carbon. 41 (10): 1889–1896.

Zhu, L., Y. Xiu, D.W. Hess, and C.P. Wong. 2005. Aligned carbon nanotube stacks by water-assisted selective etching. Nano Lett. 5 (12): 2641–2645.

Unrau, C.J., V.R. Katta, and R.L. Axelbaum. 2010. Characterization of diffusion flames for synthesis of single-walled carbon nanotubes. Combust. Flame. 157 (9): 1643–1648.

Chun Zeng, H. 2007. Ostwald Ripening: A Synthetic Approach for Hollow Nanomaterials. Curr. Nanosci. 3 (2): 177–181.

Amama, P.B., C.L. Pint, L. McJilton, S.M. Kim, E. A. Stach, P.T. Murray, R.H. Hauge, and B. Maruyama. 2009. Role of water in super growth of single-walled carbon nanotube carpets. Nano Lett. 9 (1): 44–49.

Yamada, T., A. Maigne, M. Yudasaka, K. Mizuno, D.N. Futaba, M. Yumura, S. Iijima, and K. Hata. 2008. Revealing the secret of water-assisted carbon nanotube synthesis by microscopic observation of the interaction of water on the catalysts. Nano Lett. 8 (12): 4288–4292.

Liu, H., Y. Zhang, R. Li, X. Sun, F. Wang, Z. Ding, P. Merel, and S. Desilets. 2010. Aligned synthesis of multi-walled carbon nanotubes with high purity by aerosol assisted chemical vapor deposition: Effect of water vapor. Appl. Surf. Sci. 256 (14): 4692–4696.

Li, X., A. Westwood, A. Brown, R. Brydson, and B. Rand. 2008. Water assisted synthesis of clean single-walled carbon nanotubes over a Fe2O3/Al2O3 binary aerogel catalyst. New Carbon Mater. 23 (4): 351–355.

Futaba, D.N., K. Hata, T. Yamada, K. Mizuno, M. Yumura, and S. Iijima. 2005. Kinetics of Water-Assisted Single-Walled Carbon Nanotube Synthesis Revealed by a Time-Evolution Analysis. Phys. Rev. Lett. 95 (5:) 056104.

Hata, K., D.N. Futaba, K. Mizuno, T. Namai, M. Yumura, and S. Iijima. 2004. Water-assisted highly efficient synthesis of impurity-free single-walled carbon nanotubes. Science. 306 (5700): 1362–1364.

Yoshida, A., T. Udagawa, Y. Momomoto, H. Naito, and Y. Saso. 2013. Experimental study of suppressing effect of fine water droplets on propane/air premixed flames stabilized in the stagnation flowfield. Fire Saf. J. 58: 84–91.

Zhu, Z., Y. Lu, D. Qiao, S. Bai, T. Hu, L. Li, and J. Zheng. 2005. Self-catalytic behavior of carbon nanotubes. J. Am. Chem. Soc. 127 (45): 15698–156989.

Romero, P., R. Oro, M. Campos, J.M. Torralba, and R. Guzman de Villoria. 2015. Simultaneous synthesis of vertically aligned carbon nanotubes and amorphous carbon thin films on stainless steel. Carbon. 82: 31–38.

Merchan-Merchan, W., A. Saveliev, L. A. Kennedy, and A. Fridman. 2002. Formation of carbon nanotubes in counter-flow, oxy-methane diffusion flames without catalysts. Chem. Phys. Lett. 354 (1-2): 20–24..

Martin. I, G. Rius, P. Atienzar, L. Teruel, N. Mestres, F. Perez-Murano, H. Garcia, P. Godignon, A. Corma, and E. Lora-Tamayo. 2008. CVD oriented growth of carbon nanotubes using AlPO4-5 and L type zeolites. Microelectron. Eng. 85 (5-6): 1202–1205.

Yuan, D., L. Ding, H. Chu, Y. Feng, T.P. McNicholas, and J. Liu. 2008. Horizontally aligned single-walled carbon nanotube on quartz from a large variety of metal catalysts. Nano Lett. 8 (8): 2576-2579.

Liu, B., W. Ren, L. Gao, S. Li, S. Pei, C. Liu, C. Jiang, and H.M. Cheng. 2009. Metal-catalyst-free growth of single-walled carbon nanotubes. J. Am. Chem. Soc. 131 (6): 2082–2083.

Simon, A., M. Seyring, S. Kamnitz, H. Richter, I. Voigt, M. Rettenmayr, and U. Ritter. 2015. Carbon nanotubes and carbon nanofibers fabricated on tubular porous Al2O3 substrates. Carbon. 90: 25–33.

Baker, R.T.K., M.A. Barber, P.S. Harris, F.S. Feates, and R.J. Waite. 1972. Nucleation and Growth of Carbon Deposits from the Nickel Catalyzed Decomposition of Acetylene. J. Catal. 26 (1): 51–62.

Borowiak-Palen, E., A. Bachmatiuk, M.H. Rümmeli, T. Gemming, M. Kruszynska, and R.J. Kalenczuk. 2008. Modifying CVD synthesised carbon nanotubes via the carbon feed rate. Phys. E Low-Dimensional Syst. Nanostructures. 40 (7): 2227–2230.

Park, S., W. Song, Y. Kim, I. Song, S.H. Kim, S. Il Lee, S.W. Jang, and C.Y. Parkl. 2014. Effect of growth pressure on the synthesis of vertically aligned carbon nanotubes and their growth termination. J. Nanosci. Nanotechnol. 14 (7): 5216–20.

Maruyama, S., R. Kojima, Y. Miyauchi, S. Chiashi, and M. Kohno. 2002. Low-temperature synthesis of high-purity single-walled carbon nanotubes from alcohol. Chem. Phys. Lett. 360 (3-4): 229–234. 2.

Qian, W., H. Yu, F. Wei, Q. Zhang, and Z. Wang. 2002. Synthesis of carbon nanotubes from liquefied petroleum gas containing sulfur. Carbon. 40 (15): 2968–2970.

Huang, J., Q. Zhang, F. Wei, W. Qian, D. Wang, and L. Hu. 2008. Liquefied petroleum gas containing sulfur as the carbon source for carbon nanotube forests. Carbon. 46 (2): 291–296.

Zhao, J., X. Guo, Q. Guo, L. Gu, Y. Guo, and F. Feng. 2011. Growth of carbon nanotubes on natural organic precursors by chemical vapor deposition. Carbon. 49 (6): 2155–2158.

Deep, A. and N. Arya. 2012. Optimization of Flame Synthesis of CNT Structures using Statistical Design of Experiments ( SDOE ). Int. J. Sci. Eng. Res. 3 (11): 305–312.

Pan, C. and X. Xu. 2002. Synthesis of carbon nanotubes from ethanol flame. J. Mater. Sci. Lett. 21 (15): 1207–1209.

Bajad, G.S., S.K. Tiwari, and R.P. Vijayakumar. 2015. Synthesis and characterization of CNTs using polypropylene waste as precursor. Mater. Sci. Eng. B. 194: 68–77.

Tsai, S.H., C.T. Shiu, S.H. Lai, and H.C. Shih. 2002. Tubes on tube—a novel form of aligned carbon nanotubes. Carbon. 40 (9): 1597–1600.

Santini, C.A., P.M. Vereecken, and C. Van Haesendonck. 2012. Growth of carbon nanotube branches by electrochemical decoration of carbon nanotubes. Mater. Lett. 88: 33–35.

Ngo, Q., A.M. Cassell, V. Radmilovic, J. Li, S. Krishnan, M. Meyyappan, andn C.Y. Yang. 2007. Palladium catalyzed formation of carbon nanofibers by plasma enhanced chemical vapor deposition. Carbon. 45 (2): 424–428.

Liu, H. and D.S. Dandy. 1996. Nucleation Kinetics Of Diamond On Carbide-Forming Substrates During Cvd — I . Transient Nucleation Stage. J. Electrochem. Soc. 143 (3): 1104–1109.

Zhang, Y. and K. Smith. 2005. A kinetic model of CH4 decomposition and filamentous carbon formation on supported Co catalysts. J. Catal. 231 (2): 354–364.

Yun, J. and D.S. Dandy. 2005. A kinetic model of diamond nucleation and silicon carbide interlayer formation during chemical vapor deposition. Diam. Relat. Mater. 14 (8): 1377–1388.

Naha, S. and I.K. Puri. 2008. A model for catalytic growth of carbon nanotubes. J. Phys. D. Appl. Phys. 41 (6): 065304.

Hou, S.S., W.C. Huang, and T.H. Lin. 2012. Flame synthesis of carbon nanostructures using mixed fuel in oxygen-enriched environment. J. Nanoparticle Res. 14 (11): 1–11.

Dai, H., A.G. Rinzler, P. Nikolaev, A. Thess, D.T. Colbert, and R.E. Smalley. 1996. Single-wall nanotubes produced by metal-catalyzed disproportionation of carbon monoxide. Chem. Phys. Lett. 260 (3-4): 471–475.

Banerjee, S., S. Naha, and I.K. Puri. 2008. Molecular simulation of the carbon nanotube growth mode during catalytic synthesis. Appl. Phys. Lett. 92 (23): 2006–2009.

Lander, J.J., H.E. Kern, and A.L. Beach. 1952. Solubility and Diffusion Coefficient of Carbon in Nickel: Reaction Rates of Nickel-Carbon Alloys with Barium Oxide. J. Appl. Phys. 23 (12): 1305.

Xu, F., H. Zhao, and S.D. Tse. 2007. Carbon nanotube synthesis on catalytic metal alloys in methane/air counterflow diffusion flames. Proc. Combust. Inst. 31 (2): 1839–1847.

Cheung, C.L., A. Kurtz, H. Park, and C.M. Lieber. 2002. Diameter-controlled synthesis of carbon nanotubes. J. Phys. Chem. B. 106 (10): 2429–2433.

Michalkiewicz, B. and J. Majewska. 2014. Diameter-controlled carbon nanotubes and hydrogen production. Int. J. Hydrogen Energy. 39 (9): 4691–4697.

Kuwana, K. and K. Saito. 2005. Modeling CVD synthesis of carbon nanotubes: Nanoparticle formation from ferrocene. Carbon. 43 (10): 2088–2095.

Hou, S.S., D.H. Chung, and T.H. Lin. 2009. Flame synthesis of carbon nanotubes in a rotating counterflow. J. Nanosci. Nanotechnol. 9 (8): 4826–4833.

Manciu, F.S., J. Camacho, and A.R. Choudhuri. 2008. Flame synthesis of multi-walled carbon nanotubes using CH4-H2 fuel blends. Fullerenes, Nanotub. Carbon Nanostructures. 16 (4): 231–246.

Nasibulin, A.G., P. V. Pikhitsa, H. Jiang, and E.I. Kauppinen. 2005. Correlation between catalyst particle and single-walled carbon nanotube diameters. Carbon. 43 (11): 2251–2257.

Chen, L.C., C.Y. Wen, C.H. Liang, W.K. Hong, K.J. Chen, H.C. Cheng, C.S. Shen, C.T. Wu, and K.H. Chen. 2002. Controlling Steps During Early Stages of the Aligned Growth of Carbon Nanotubes Using Microwave Plasma Enhanced Chemical Vapor Deposition. Adv. Funct. Mater. 12 (10): 687–692.

Yu, Q., G. Qin, H. Li, Z. Xia, Y. Nian, and S.S. Pei. 2006. Mechanism of horizontally aligned growth of single-wall carbon nanotubes on R-plane sapphire. J. Phys. Chem. B. 110 (45): 22676–22680.

Pope, C.J. and J.B. Howard. 1997. Simultaneous Particle and Molecule Modeling (SPAMM): An Approach for Combining Sectional Aerosol Equations and Elementary Gas-Phase Reactions. Aerosol Sci. Technol. 27 (1): 73–94.

Ramponi, R. and B. Blocken. 2012. CFD simulation of cross-ventilation flow for different isolated building configurations: Validation with wind tunnel measurements and analysis of physical and numerical diffusion effects. J. Wind Eng. Ind. Aerodyn. 104-106: 408–418.

Mitrakos, D., E. Hinis, and C. Housiadas. 2007. Sectional Modeling of Aerosol Dynamics in Multi-Dimensional Flows. Aerosol Sci. Technol. 41 (12): 1076–1088.

Endo, H., K. Kuwana, K. Saito, D. Qian, R. Andrews, and E.A. Grulke. 2004. CFD prediction of carbon nanotube production rate in a CVD reactor. Chem. Phys. Lett. 387 (4-6): 307–311.

Celnik, M., R. West, N. Morgan, M. Kraft, A. Moisala, J. Wen, W. Green, and H. Richter. 2008. Modelling gas-phase synthesis of single-walled carbon nanotubes on iron catalyst particles. Carbon. 46 (3): 422–433.






Science and Engineering

How to Cite

OPTIMIZING FLAME SYNTHESIS OF CARBON NANOTUBES: EXPERIMENTAL AND MODELLING PERSPECTIVES. (2016). Jurnal Teknologi, 78(8-4). https://doi.org/10.11113/jt.v78.9595