Skip to content
Research Article Open access CC BY 4.0

Engineering Nascent Disentangled Ultra-High-Molecular-Weight Polyethylene Based on Heterogeneous Catalytic Polymerization

Lei Li

Organics · pp. 32–32 · Published 21 Jul 2025

10.3390/org6030032

Abstract

Ultra-high-molecular-weight polyethylene (UHMWPE) is a pivotal material in engineering and biomedical applications due to its exceptional mechanical strength, wear resistance, and impact performance. However, its extreme melt viscosity, caused by extensive chain entanglements, severely limits processability via conventional melt-processing techniques. Recent advances in catalytic synthesis have enabled the production of disentangled UHMWPE (dis-UHMWPE), which exhibits enhanced processability while retaining superior mechanical properties. Notably, heterogeneous catalytic systems, utilizing supported fluorinated bis (phenoxy-imine) titanium (FI) catalysts, polyhedral oligomeric silsesquioxanes (POSS)-modified Z-N catalysts, and other novel catalysts, have emerged as promising solutions, combining structural control with industrial feasibility. Moreover, optimizing polymerization conditions further enhances chain disentanglement while maintaining ultra-high molecular weights. These systems utilize nanoscale supports and ligand engineering to spatially isolate active sites, tailor the chain propagation/crystallization kinetics, and suppress interchain entanglement during polymerization. Furthermore, characterization techniques such as melt rheology and differential scanning calorimetry (DSC) provide critical insights into chain entanglement, revealing distinct reorganization kinetics and bimodal melting behavior in dis-UHMWPE. This development of hybrid catalytic systems opens up new avenues for solid-state processing and industrial-scale production. This review highlights recent advances concerning interaction between catalyst design, polymerization control, and material performance, ultimately unlocking the full potential of UHMWPE for next-generation applications.

Polyethylene Polymerization Ultra-high-molecular-weight polyethylene Catalysis Materials science Chemical engineering Polymer chemistry Chemistry

References (133)

  1. 1 Drakopoulos, S.X., Tarallo, O., Guan, L., Martin-Fabiani, I., and Ronca, S. (2020). Nanocomposites of Au/Disentangled UHMWPE: A Combined Optical and Structural Study. Molecules, 25. [DOI]
  2. 2 Kim, 2022, Origin of high thermal conductivity in disentangled ultra-high molecular weight polyethylene films: Ballistic phonons within enlarged crystals [DOI]
  3. 3 Ma, 2024, Preparation of Toughened Bimodal Ultrahigh-Molecular-Weight Polyethylene by a Coanchoring Strategy [DOI]
  4. 4 Zhang, 2020, The chain dis-entanglement effect of polyhedral oligomeric silsesquioxanes (POSS) on ultra-high molecular weight polyethylene (UHMWPE) [DOI]
  5. 5 Forster, 2015, Long-term stability of UHMWPE fibers [DOI]
  6. 6 Huang, J., Zhang, X., Gu, T., Zhang, F., Niu, Y., and Liu, S. (2024). Effect of Hot-Pressing Process on Mechanical Properties of UHMWPE Fiber Non-Woven Fabrics. Materials, 17. [DOI]
  7. 7 Hussain, M., Naqvi, R.A., Abbas, N., Khan, S.M., Nawaz, S., Hussain, A., Zahra, N., and Khalid, M.W. (2020). Ultra-High-Molecular-Weight-Polyethylene (UHMWPE) as a Promising Polymer Material for Biomedical Applications: A Concise Review. Polymers, 12. [DOI]
  8. 8 Kamal, 2016, Optical properties of ultra-high molecular weight polyethylene (UHMWPE): A material of choice for total joint applications [DOI]
  9. 9 Tang, 2022, Metallocene Polyolefins Reinforced by Low-Entanglement UHMWPE through Interfacial Entanglements [DOI]
  10. 10 Tao, 2021, Exploring the entangled state and molecular weight of UHMWPE on the microstructure and mechanical properties of HDPE/UHMWPE blends [DOI]
  11. 11 Li, 2024, Current research status of high-performance UHMWPE fiber: A review [DOI]
  12. 12 Mohammed, 2016, Improving the friction and wear of poly-ether-etherketone (PEEK) by using thin nano-composite coatings [DOI]
  13. 13 Panin, S.V., Kornienko, L.A., Alexenko, V.O., Buslovich, D.G., Bochkareva, S.A., and Lyukshin, B.A. (2020). Increasing Wear Resistance of UHMWPE by Loading Enforcing Carbon Fibers: Effect of Irreversible and Elastic Deformation, Friction Heating, and Filler Size. Materials, 13. [DOI]
  14. 14 Minn, 2008, DLC and UHMWPE as hard/soft composite film on Si for improved tribological performance [DOI]
  15. 15 Li, 2023, The influence of penetration angle on anti-penetration performance and reverse penetration ricochet phenomenon of UHMWPE laminates [DOI]
  16. 16 Wang, 2023, Ballistic impact response of flexible and rigid UHMWPE textile composites: Experiments and simulations [DOI]
  17. 17 Zhang, 2024, Ballistic performance of UHMWPE fiber laminates with pre-formed holes [DOI]
  18. 18 Gao, 2024, Structural evolution of low-entangled UHMWPE films with reserved shish crystals and different molecular weights during hot stretching [DOI]
  19. 19 Lame, 2007, Microstructural origin of physical and mechanical properties of ultra high molecular weight polyethylene processed by high velocity compaction [DOI]
  20. 20 Xing, 2024, Structural evolution of low-entangled UHMWPE gel films with reserved shish crystals and different entanglement degrees during stretching [DOI]
  21. 21 Zhang, D. (2014). 5—Gel spinning of synthetic polymer fibres. Advances in Filament Yarn Spinning of Textiles and Polymers, Woodhead Publishing.
  22. 22 Wang, 2018, Study on structures and properties of ultra-hot drawing UHMWPE fibers fabricated via dry spinning method [DOI]
  23. 23 Wang, 2024, Structure Formation and Unexpected Ultrafast Re-entanglement Dynamics of Disentangled Ultrahigh Molecular Weight Polyethylene [DOI]
  24. 24 Khalil, Y., Hopkinson, N., Kowalski, A., and Fairclough, J.P. (2019). Characterisation of UHMWPE Polymer Powder for Laser Sintering. Materials, 12. [DOI]
  25. 25 Wu, 2023, Nascent disentangled UHMWPE: Origin, synthesis, processing, performances and applications [DOI]
  26. 26 Yilmaz, 2023, A new approach for high-quality production of UHMWPE by applying powder vibration densification before sintering [DOI]
  27. 27 Zhang, 2023, Access to Disentangled Ultrahigh Molecular Weight Polyethylene via a Binuclear Synergic Effect [DOI]
  28. 28 Li, 2025, Catalytic strategies for synthesizing disentangled ultrahigh molecular weight polyethylene via homogeneous FI catalyst-based polymerization [DOI]
  29. 29 Liang, 2020, Efficient Synthesis of Low-Polydispersity UHMWPE by Elevating Active Sites on Anchored POSS Molecules [DOI]
  30. 30 Yue, 2020, Reduced Entanglement Density of Ultrahigh-Molecular-Weight Polyethylene Favored by the Isolated Immobilization on the MgCl2 (110) Plane [DOI]
  31. 31 Drakopoulos, 2018, Entanglement dynamics in ultra-high molecular weight polyethylene as revealed by dielectric spectroscopy [DOI]
  32. 32 Li, 2018, Heterogeneous distribution of chain mobility in nascent UHMWPE in the less entangled state [DOI]
  33. 33 Vittoria, 2017, Demystifying Ziegler–Natta Catalysts: The Origin of Stereoselectivity [DOI]
  34. 34 Hedlund, 2022, Local structure mapping of gel-spun ultrahigh-molecular-weight polyethylene fibers [DOI]
  35. 35 Ivan’kova, E., Egorov, V., Marikhin, V., Myasnikova, L., Boiko, Y., and Radovanova, E. (2022). Fundamental Structural and Kinetic Principals of High Strength UHMWPE Fibers Production by Gel-Technology. Polymers, 14. [DOI]
  36. 36 Shen, 2018, Drawing behavior and mechanical properties of ultra-high molecular weight polyethylene blends with a linear polyethylene wax [DOI]
  37. 37 Yu, 2021, Structure and properties of gel-spun ultra-high molecular weight polyethylene fibers obtained from industrial production line [DOI]
  38. 38 Bodkhe, 2023, Ti-iminocarboxylate catalyzed polymerization of ethylene to highly crystalline, disentangled, ultrahigh molecular weight polyethylene [DOI]
  39. 39 Forte, 2017, Synthesis of Disentangled Ultra-High Molecular Weight Polyethylene: Influence of Reaction Medium on Material Properties [DOI]
  40. 40 Tuskaev, 2019, Binuclear and Hexanuclear Ti(IV) Complexes Supported by [OOOO]4–-type Ligand for Preparing Disentangled UHMWPE [DOI]
  41. 41 Bally, 2010, Homogeneous Polymerization: Benefits Brought by Microprocess Technologies to the Synthesis and Production of Polymers [DOI]
  42. 42 Rahimpour, 2025, Chapter 2—Ethylene polymerization with homogeneous catalysts
  43. 43 Chen, J., Qu, S., Li, X., Wei, Y., Li, Q., Wen, Z., and Guo, Z. (2025). Single-Site Catalyst for the Synthesis of Disentangled Ultra-High-Molecular-Weight Polyethylene. Polymers, 17. [DOI]
  44. 44 Rahimpour, 2025, Chapter 4—Homogeneous polymerization with metallocene catalysts
  45. 45 Johannsmann, 2023, Particle fouling at hot reactor walls monitored In situ with a QCM-D and modeled with the frequency-domain lattice Boltzmann method [DOI]
  46. 46 Bajya, 2023, Exploration of disentangled UHMWPE tape as a soft body armour material [DOI]
  47. 47 Wencke, 2022, Disentangled UHMWPE@silica powders for potential use in power bed fusion based additive manufacturing [DOI]
  48. 48 Antonov, 2021, Post-metallocene catalysts for the synthesis of ultrahigh molecular weight polyethylene: Recent advances [DOI]
  49. 49 Birajdar, 2023, Emerging trends in olefin polymerization: A perspective [DOI]
  50. 50 Patel, 2020, Ultrahigh molecular weight polyethylene: Catalysis, structure, properties, processing and applications [DOI]
  51. 51 Li, K.-T., and Wu, L.-H. (2017). Constrained Geometry Organotitanium Catalysts Supported on Nanosized Silica for Ethylene (co)Polymerization. Molecules, 22. [DOI]
  52. 52 Shukla, 2022, Disentangled ultrahigh molecular weight polyethylene thin film as a transparent substrate for flexible flat panel display [DOI]
  53. 53 Dordinejad, 2018, Time-sweep rheometry for evaluating polyethylene degradation behavior: Effect of formulation and process conditions [DOI]
  54. 54 Salehiyan, 2024, A review on rheological approaches as a perfect tool to monitor thermal degradation of biodegradable polymers [DOI]
  55. 55 Hawke, 2019, Nonequilibrium Melt State of Ultra-High-Molecular-Weight Polyethylene: A Theoretical Approach on the Equilibrium Process [DOI]
  56. 56 Gote, 2025, Solid-State Processing of In Situ Blended Prepolymer with Z–N Synthesized UHMWPE: Role of the Prepolymer [DOI]
  57. 57 Lai, 2025, State-of-the-art heterogeneous polymerization kinetic modelling processes and their applications [DOI]
  58. 58 Liu, 2019, 100th Anniversary of Macromolecular Science Viewpoint: Heterogenous Reversible Deactivation Radical Polymerization at Room Temperature. Recent Advances and Future Opportunities [DOI]
  59. 59 Ribeiro, 2025, Introduction to Polymerization and Depolymerization
  60. 60 Shi, 2025, Heterogeneously catalyzed supramolecular polymerization: Essential roles of nucleation and fragmentation-induced autocatalysis in chiral transfer [DOI]
  61. 61 Romano, 2014, Influence of Polymerization Conditions on Melting Kinetics of Low Entangled UHMWPE and Its Implications on Mechanical Properties [DOI]
  62. 62 Chen, 2015, Phase structure and mechanical properties of disentangled ultra-high molecular weight polyethylene/polyhedral oligomeric silsesquioxane nanocomposites in a solid state [DOI]
  63. 63 Li, 2015, Influence of Polyhedral Oligomeric Silsesquioxane Structure on the Disentangled State of Ultrahigh Molecular Weight Polyethylene Nanocomposites during Ethylene in Situ Polymerization [DOI]
  64. 64 Romano, 2015, Aluminoxane co-catalysts for the activation of a bis phenoxyimine titanium (IV) catalyst in the synthesis of disentangled ultra-high molecular weight polyethylene [DOI]
  65. 65 Romano, 2015, A Hemi-metallocene Chromium Catalyst with Trimethylaluminum-Free Methylaluminoxane for the Synthesis of Disentangled Ultra-High Molecular Weight Polyethylene [DOI]
  66. 66 Bravaya, 2011, Effect of trimethylaluminum on the polymerization of ethylene with the catalytic system Bis[N-(3,5-di-tert-butylsalicylidene)-2,3,5,6-tetrafluoroanilinato]titanium(IV) dichloride-methylaluminoxane [DOI]
  67. 67 Li, 2014, Disentangled UHMWPE/POSS nanocomposites prepared by ethylene in situ polymerization [DOI]
  68. 68 Makio, 2002, FI Catalysts: A New Family of High Performance Catalysts for Olefin Polymerization [DOI]
  69. 69 Matsui, 2001, FI Catalysts: Super active new ethylene polymerization catalysts [DOI]
  70. 70 Rastogi, 2011, Unprecedented High-Modulus High-Strength Tapes and Films of Ultrahigh Molecular Weight Polyethylene via Solvent-Free Route [DOI]
  71. 71 Ronca, 2012, Improving the performance of a catalytic system for the synthesis of ultra high molecular weight polyethylene with a reduced number of entanglements [DOI]
  72. 72 De Souza Gomes, A. (2012). FI Catalyst for Polymerization of Olefin. Polymerization, IntechOpen. [DOI]
  73. 73 Talebi, 2010, Molar Mass and Molecular Weight Distribution Determination Of UHMWPE Synthesized Using a Living Homogeneous Catalyst [DOI]
  74. 74 Chai, 2019, Ultrasmall Nanoparticles Diluted Chain Entanglement in Polymer Nanocomposites [DOI]
  75. 75 Lichtenhan, 2019, Chain Disentanglements and Oxygen Transmission Reduction in LDPE/POSS Nanocomposites. Influence of POSS Size [DOI]
  76. 76 Lichtenhan, 2019, POSS driven chain disentanglements, decreased the melt viscosity and reduced O2 transmission in polyethylene [DOI]
  77. 77 Spronck, 2018, Synthesis of Disentangled Ultra-High Molecular Weight Polyethylene using Vanadium(V)-Based Catalysts [DOI]
  78. 78 Kenyon, 2018, Controlled Polymerization in Polar Solvents to Ultrahigh Molecular Weight Polyethylene [DOI]
  79. 79 Hu, 2018, Effect of short-chain branching on the tie chains and dynamics of bimodal polyethylene: Molecular dynamics simulation [DOI]
  80. 80 AlSalem, 2024, Melt blending of commercial linear polyethylene with low-entangled ultra-high molecular weight polyethylene: From dispersion compatibility to viscoelastic scaling laws [DOI]
  81. 81 Orupattur, 2020, Catalytic materials and chemistry development using a synergistic combination of machine learning and ab initio methods [DOI]
  82. 82 Abedi, 2014, A review of clay-supported Ziegler–Natta catalysts for production of polyolefin/clay nanocomposites through in situ polymerization [DOI]
  83. 83 Wang, 2020, Functionalized Phenoxy-Imine Catalyst for Synthesizing Highly Crystalline Nascent UHMWPEs. 1. Molecular Weight Characteristics and Polymer Morphologies [DOI]
  84. 84 Yao, 2014, 13C Solid State NMR Characterization of Structure and Orientation Development in the Narrow and Broad Molar Mass Disentangled UHMWPE [DOI]
  85. 85 Zhao, Y., Liang, Y., Yao, Y., Wang, H., Lin, T., Gao, Y., Wang, X., and Xue, G. (2023). Chain Dynamics of Partially Disentangled UHMWPE around Melting Point Characterized by 1H Low-Field Solid-State NMR. Polymers, 15. [DOI]
  86. 86 Liu, 2016, Heterogeneous Distribution of Entanglements in a Nonequilibrium Polymer Melt of UHMWPE: Influence on Crystallization without and with Graphene Oxide [DOI]
  87. 87 Pandey, 2011, Heterogeneity in the Distribution of Entanglement Density during Polymerization in Disentangled Ultrahigh Molecular Weight Polyethylene [DOI]
  88. 88 Rastogi, 2007, The role of the amorphous phase in melting of linear UHMW-PE; implications for chain dynamics [DOI]
  89. 89 Ye, 2023, Novel determining technique for the entanglement degree of ultra-high molecular weight polyethylene [DOI]
  90. 90 Zhong, 2024, Structural Evolution of High-Entanglement Ultrahigh Molecular Weight Polyethylene Films with Reserved Shish Crystals during the Hot Stretching Process [DOI]
  91. 91 Chen, 2022, Structural evolution of UHMWPE gel fibers as high degree plasticized system during stretching: An in-situ wide and small angle X-ray scattering study [DOI]
  92. 92 Welzel, 2024, Fouling During Polymerization in Different Continuous Reactor Setups [DOI]
  93. 93 Mao, 2024, Mitigation of fouling problem and optimization of treatment effect in the polyvinylidene fluoride (PVDF) based electrochemical membrane bioreactor (EMBR) [DOI]
  94. 94 Rohman, 2022, Nonlinear Control of Fouling in Polyethylene Reactors [DOI]
  95. 95 Rust, S., Osenberg, M., Musch, T., and Pauer, W. (2024). Ultrasonic and conversion-based inline fouling measurements for continuous emulsion copolymerisation of vinyl acetate in a tubular reactor. Sci. Rep., 14. [DOI]
  96. 96 Evans, 2025, Strategies for enhancing the processability of UHMWPE [DOI]
  97. 97 Fedorenko, E., and Luinstra, G.A. (2025). In Situ Polymerization and Synthesis of UHMWPE/Carbon Fiber Composites. Polymers, 17. [DOI]
  98. 98 Wang, 2024, Research on Chain Diffusion and Entanglement via Controlling the Sintering Process of Nascent UHMWPE [DOI]
  99. 99 Heidari, 2018, In Situ Synthesis of Ultrahigh Molecular Weight Polyethylene/Graphene Oxide Nanocomposite Using the Immobilized Single-site Catalyst [DOI]
  100. 100 Oleynik, 2020, Highly active titanium(IV) dichloride FI catalysts bearing a diallylamino group for the synthesis of disentangled UHMWPE [DOI]
  101. 101 Hui, 2018, Influence of the Fragmentation of POSS-Modified Heterogeneous Catalyst on the Formation of Chain Entanglements [DOI]
  102. 102 Yang, 2024, Silica-supported catalyst for the synthesis of low entangled UHMWPE suitable for solid-state processing
  103. 103 Gote, 2023, Unprecedented Mechanical Properties in Linear UHMWPE Using a Heterogeneous Catalytic System [DOI]
  104. 104 Gote, 2023, Influence of diverse MgClx/R’nClmAly(OR)z activators/supports in tailoring of entangled state of UHMWPE
  105. 105 Li, 2016, Immobilization of isolated FI catalyst on polyhedral oligomeric silsesquioxane-functionalized silica for the synthesis of weakly entangled polyethylene [DOI]
  106. 106 Zhou, 2022, Chain disentanglement in POSS/UHMWPE composites prepared via in-situ polymerization [DOI]
  107. 107 Zhou, 2022, Study on the effects of soluble POSS on chain disentanglement in UHMWPE polymerization [DOI]
  108. 108 Chen, 2021, Synthesis of Weakly Entangled Ultra-High-Molecular-Weight Polyethylene with a Fine Particle Size [DOI]
  109. 109 Chen, 2019, Entanglement Formation Mechanism in the POSS Modified Heterogeneous Ziegler–Natta Catalysts [DOI]
  110. 110 Li, 2018, Facile high-temperature synthesis of weakly entangled polyethylene using a highly activated Ziegler-Natta catalyst [DOI]
  111. 111 Guo, 2022, Preparation of Weakly Entangled and Fine-sized Ultra-High-Molecular Weight Polyethylene by a MgCl2-Based Ziegler–Natta Catalyst [DOI]
  112. 112 Zhou, 2022, Influence of Modified Ziegler–Natta Catalyst on the Entanglement Behavior and Properties of Ultrahigh-Molecular-Weight Polyethylene (UHMWPE) [DOI]
  113. 113 Chen, 2023, In Situ Synthesized Self-Reinforced HDPE/UHMWPE Composites with High Content of Less Entangled UHMWPE and High Gradient-Distributed Oriented Structures [DOI]
  114. 114 Buffet, 2021, Supported permethylindenyl titanium catalysts for the synthesis of disentangled ultra-high molecular weight polyethylene (disUHMWPE) [DOI]
  115. 115 Gote, 2018, Judicious Reduction of Supported Ti Catalyst Enables Access to Disentangled Ultrahigh Molecular Weight Polyethylene [DOI]
  116. 116 Cao, 2022, Long-term efficiency for reducing entanglements of nascent polyethylene by a polystyrene-modified Ziegler-Natta catalyst [DOI]
  117. 117 Christakopoulos, 2023, Gas-phase polymerization of ultra-high molecular weight polyethylene with decreased entanglement density [DOI]
  118. 118 Chammingkwan, 2021, Less Entangled Ultrahigh-Molecular-Weight Polyethylene Produced by Nano-Dispersed Ziegler–Natta Catalyst [DOI]
  119. 119 Wang, 2022, Contribution of the Initially Entangled State and Particle Size to the Sintering Kinetics of UHMWPE [DOI]
  120. 120 Barrera, 2017, Designing polyethylene characteristics by modification of the support for FI catalyst
  121. 121 Gagieva, S.C., Magomedov, K.F., Tuskaev, V.A., Bogdanov, V.S., Kurmaev, D.A., Golubev, E.K., Denisov, G.L., Nikiforova, G.G., Evseeva, M.D., and Saracheno, D. (2022). Effect of Activator and Outgoing Ligand Nature on the Catalytic Behavior of Bis(phenoxy-imine) Ti(IV) Complexes in the Polymerization of Ethylene and Its Copolymerization with Higher Olefins. Polymers, 14. [DOI]
  122. 122 Gagieva, 2022, Immobilized on MgCl2 bis(phenoxy-imine) complexes of Ti and Zr as catalysts for preparing UHMWPE and ethylene/higher α-olefin copolymers [DOI]
  123. 123 Li, 2011, Effect of cocatalysts on ethylene polymerization with fluorinated bisphenoxyimine titanium as a catalyst [DOI]
  124. 124 Liu, 2022, Ultra-high molecular weight polyethylene: Preparation and applications [DOI]
  125. 125 March, S., Hand, M., Morrissey, L., and Kelsey, D. (2025). Thermal buffering-controlled temperature variation between Mg–Al-rich rocks and migmatites. Sci. Rep., 15. [DOI]
  126. 126 Hao, 2020, Study on thermal buffering effect of phase change material on press- pack IGBT [DOI]
  127. 127 Yang, 2020, Structural modification of phenoxyimine titanium complexes and activation studies with alkylaluminum compounds [DOI]
  128. 128 Sellinger, 1996, Silsesquioxanes as Synthetic Platforms. Thermally Curable and Photocurable Inorganic/Organic Hybrids [DOI]
  129. 129 Ayandele, 2012, Polyhedral Oligomeric Silsesquioxane (POSS)-Containing Polymer Nanocomposites [DOI]
  130. 130 Guo, 2017, Polyethylene/polyhedral oligomeric silsesquioxanes composites: Dielectric, thermal and rheological properties [DOI]
  131. 131 Raftopoulos, 2016, Segmental dynamics in hybrid polymer/POSS nanomaterials [DOI]
  132. 132 Huang, 2017, Melt processing and structural manipulation of highly linear disentangled ultrahigh molecular weight polyethylene [DOI]
  133. 133 Heidari, 2018, A disentangled state using TiCl4/MgCl2 catalyst: A case study of polyethylene [DOI]

Cited by 5

Showing 1 of 5 known citations — external sources report more than can currently be individually listed.

Article metrics

Real usage data collected on this platform.

0

Page views

0

PDF downloads

0

Outbound clicks

5

Citations

Views by country

Approximate, from request IP at view time — not citizenship or institution. Countries with fewer than 5 views are grouped as "Other".

No views recorded yet.

Traffic sources

Referring site, by host.

No traffic recorded yet.

Views and downloads exclude known bots/crawlers. Citations combines this platform's own DOI-resolved index with each external source's own reported total — see Cited by above for individually listed citing works. Last refreshed 0 seconds ago.