2024
76. K. Satake, K. Narazaki, H. Abe, K. Yanagihashi, M. Mizukami, Y.i Suzuri, T. Chiba*, J. Kido, Low-Temperature Annealing of Inkjet-Printed CsPbBr3 Perovskite Nanocrystal Film for Light-Emitting Diodes, ACS Appl. Nano Mater. 2024, Accepted.
75. K. Nagasawa, T. Sano*, V. C. NGUYEN, Y. Okuyama, Y. Sayama, R. Oikawa, K. Hoshi, T. Chiba, J. Kido*, Improvement of film quality and solar cell properties of perovskite by the addition of N-benzylhydroxylamine, Applied Physics Express, 2024, 17, 034001.
74. K. Yoshida, N. Oshita, T. Kimura, M. Goto, R. Oikawa, M Uwano, S. Asakura, T. Chiba, A. Masuhara*, Synthetic method of pure-red emissive CsPbI3 under ambient conditions for quantum dots light-emitting diode application, Applied Physics Express, 2024, 17, 025002.
73. K. Morii, H. Nabeta, T. Yanbe, K. Watanabe, S. Sumikoshi, T. Chiba, R. Yamakado*, S. Okada, Synthesis and Optical Properties of Anion-Responsive X-shaped π-Electronic System, ChemistrySelect 2024,9, e20230500
2023
72. K. Nagasawa, T. Sano*, V. N. Chau, K. Enomoto, Y. Okuyama, Y. Sayama, R. Oikawa, T. Chiba, J. Kido*, Improving the Photovoltaic Properties and Stability of Inverted Perovskite Solar Cells with Hydroxylamine-Based Additives, Adv. Mater. Interfaces 2023, 2300449
71. H. Ebe*, R. Suzuki, S. Sumikoshi, M. Uwano, R. Moriyama, D. Yokota, M. Otaki, K. Enomoto, T. Oto, T. Chiba*, and J. Kido*, Guanidium Iodide Treatment of Size-controlled CsPbI3 Quantum Dots for Stable Crystal Phase and Highly Efficient Red LEDs, Chem. Eng. J. 471, 144578, (2023).
70. F.-C. Liang, F.-C. Jhuang, Y.-H. Fang, J.-S. Benas, W.-C. Chen, Z.-L. Yan, W.-C. Lin, C.-J. Su, Y. Sato, T. Chiba*, J. Kido*, C.-C. Kuo*, Synergistic Effect of Cation Composition Engineering of Hybrid Cs1−xFAxPbBr3 Nanocrystals for Self-Healing Electronics Application, Adv. Mater. 35, 2207617, (2023).
69. K. Satake, Y. Sato, K. Narazaki, T. Chiba*, S. Sumikoshi, R. Moriyama, R. Suzuki, Y.-H. Cheng, K. Tamura, and J. Kido*, Fabrication of perovskite nanocrystal light-emitting diodes via inkjet printing with high-temperature annealing, ACS Appl. Opt. Mater. 1, 282–288, (2023).
2022
68. T. Chiba*, Recent advances in solution-processed organic and perovskite nanocrystal light-emitting devices, Polym. J, 54, 969-976 (2022).
67. O. J. G. L. Chevalier, T. Nakamuro*, W. Sato, S. Miyashita, T. Chiba, J. Kido, R. Shang*, E. Nakamura*, Precision Synthesis and Atomistic Analysis of Deep-Blue Cubic Quantum Dots Made via Self-Organization, J. Am. Chem. Soc. 144, 21146–21156 (2022).
66. S. Kuroyanagi, S. Kikuchi, M. Uwano, S. Sumikoshi, T. Chiba, R. Yamakado*, and S. Okada, Synthesis of 3-(Phenylcarbonyl)-1H-indazole Derivatives via Intramolecular Cyclization under Mild Conditions, Asian J. Org. Chem. 11, e202200423 (2022).
65. N. Oshita, K. Umemoto, R. Sato, T. Kimura, T. Chiba, S Asakura, H. Uji-i, Hiroshi*, A. Masuhara*, A facile reprecipitation method of Quantum-confined CsPbBr3 perovskite quantum dots for narrow-band deep-blue emission, Appl. Phys. Express 15, 065002 (2022).
64. H. Ebe, Y.-K. Wang, N. Shinotsuka, Y.-H. Cheng, M. Uwano, R. Suzuki, Y. Dong, D. Ma, S. Lee, T. Chiba*, E. H. Sargent, Junji Kido*, Energy Transfer between Size-Controlled CsPbI3 Quantum Dots for light-Emitting Diode Application. ACS Appl. Mater. Interfaces, 14, 17691–17697 (2022).
63. Y.-H. Cheng, R. Suzuki, N. Shinotsuka, H. Ebe, N. Oshita, R. Yamakado, T. Chiba*, A. Masuhara, J Kido*, Gel Permeation Chromatography Process For Highly Oriented Cs3Cu2I5 Nanocrystal Film, Sci. Rep. 12, 4620 (2022).
62. Y.-H. Cheng, R. Moriyama, H. Ebe, K. Mizuguchi, R. Yamakado, S. Nishitsuji, T. Chiba*, J. Kido, Two-Step Crystallization for Low-Oxidation Tin-Based Perovskite Light-Emitting Diodes, ACS Appl. Mater. Interfaces, 14, 22941–22949 (2022).
2021
61. Y.-H. Cheng, H. Ebe, T. Chiba*, J. Kido, Post-Synthetic Surface Treatment of Perovskite Nanocrystals for Highly Efficient Light-Emitting Diodes, Journal of the Imaging Society of Japan, 60, 606-614 (2021).
60. K. Enomoto, R. Oizumi, N. Aizawa, T. Chiba, Y.-J. Pu*, Energy Transfer from Blue-Emitting CsPbBr3 Perovskite Nanocrystals to Green-Emitting CsPbBr3 Perovskite Nanocrystals, J. Phys. Chem. C, 125, 19368-19373 (2021).
59. W.-C. Chen, Y.-H. Fang, L.-G. Chen, F.-C. Liang, Z.-L. Yan, H. Ebe, Y. Takahashi, T. Chiba*, J. Kido*, C.-C. Kuo*, High luminescence and external quantum efficiency in perovskite quantum-dots light-emitting diodes featuring bilateral affinity to silver and short alkyl ligands, Chem. Eng. J. 414, 128866 (2021).
58. Z.-L. Yan, J.-S. Benas, C.-C. Chueh, W.-C. Chen, F.-C. Liang, Z.-X. Zhang, B.-H. Lin, C.-J. Su, T. Chiba*, J. Kido*, C.-C. Kuo*, Stable blue perovskite light-emitting diodes achieved by optimization of crystal dimension through zinc bromide addition, Chem. Eng. J. 414, 128774 (2021).
2020
57. T. Chiba*, J. Sato, S. Ishikawa, Y. Takahashi, H. Ebe, S. Sumikoshi, S. Ohisa, J. Kido*, Neodymium Chloride-Doped Perovskite Nanocrystals for Efficient Blue Light-Emitting Devices, ACS Appl. Mater. Interfaces 12, 53891 (2020).
56. K. Umemoto, H. Ebe, R. Sato, J. Enomoto, N. Oshita, T. Kimura, T. Inose, T. Nakamura, T. Chiba, S. Asakura, H. Uji-I*, A. Masuhara*, Simple Production of Highly Luminescent Organometal Halide Perovskite Nanocrystals Using Ultrasound-Assisted Bead Milling, ACS Sustain. Chem. Eng. 8, 16469 (2020).
55. T. Chiba*, Y. Takahashi, J. Sato, S. Ishikawa, H. Ebe, K. Tamura, S. Ohisa, J. Kido*, Crystal Growth of Perovskite Nanocrystals via Postsynthetic Lead(II) Bromide Treatment to Increase the Colloidal Stability and Efficiency of Light-Emitting Devices, ACS Appl. Mater. Interfaces 12, 45574 (2020).
54. J. Kosai, Y. Masuda, Y. Chikayasu, Y. Takahashi, H. Hisahiro, T. Chiba, J. Kido, H. Mori, S-Vinyl Sulfide-Derived Pendant-Type Sulfone/Phenoxazine-Based Polymers Exhibiting Thermally Activated Delayed Fluorescence: Synthesis and Photophysical Property Characterization, ACS Appl. Polym. Mater. 2, 3310-3318 (2020).
53. T. Kamata, H. Sasabe, N. Ito, Y. Sukegawa, A. Arai, T. Chiba, D. Yokoyama, J. Kido, Simultaneous realization of high-efficiency, low-drive voltage, and long lifetime TADF OLEDs by multifunctional hole-transporters, J. Mater. Chem. C 8, 7200-7210 (2020).
52. M. Takeda, M. Yamamoto, K. Umemoto, B. Lyu, Y. Takahashi, S. Rodbuntum, J. Enomoto, K. Tozawa, T. Nohara, K. Tabata, R. Sato, T. Chiba, S. Asakura, M.-I. Furis, T. Yoshida, H. Uji-I, A. Masuhara, Synthesis of highly luminescent CH3NH3PbBr3 perovskite nanocrystals via a forced thin film reactor, Jpn. J. Appl. Phys. 59, SIIG02 (2020).
51. T. Chiba*, S. Ishikawa, J. Sato, Y. Takahashi, H. Ebe, S. Ohisa, J. Kido*, Blue perovskite nanocrystal light-emitting devices via the ligand exchange with adamantane diamine, Adv. Opt. Mater. 8, 2000289 (2020).
50. H. Ebe, T. Chiba*, S. Ohisa, J. Kido*, Gel Permeation Chromatography Purification Process for Highly Efficient Perovskite Nanocrystal Light-Emitting Devices, J. Photopolym. Sci. Tec. 33, 393-397 (2020)
49. Y. Tezuka, K. Umemoto, M. Takeda, Y. Takahashi, H. Ebe, J. Enomoto, S. Rodbuntum, T. Nohara, D. Fontecha, S. Asakura, T. Chiba, M.-I. Furis, T. Yoshida, H. Uji-I*, A. Masuhara*, Effects of alkylamine chain length on perovskite nanocrystals after washing and perovskite light-emitting diodes, Jpn. J. Appl. Phys. 59, SDDC04 (2020).
2019
48. S. Ohisa*, M. Suzuki, T. Chiba, J. Kido*, Doping of Tetraalkylammonium Salts in Polyethylenimine Ethoxylated for Efficient Electron Injection Layers in Solution-Processed Organic Light-Emitting Devices, ACS Appl. Mater. Interfaces 11, 25351-25357, (2019).
47. S. Ohisa*, D. Takashima, T. Chiba, J. Kido*, Low-temperature cross-linking of polyethyleneimine ethoxylated using silane coupling agents to obtain stable electron injection layers in solution-processed organic light-emitting devices, J. Mater. Chem. C, 7, 6759-6766, (2019).
46. Y. Watanabe, D. Yokoyama*, T. Koganezawa, H. Katagiri, T. Ito, S. Ohisa, T. Chiba H. Sasabe*, and J. Kido*, Control of Molecular Orientation in Organic Semiconductor Films using Weak Hydrogen Bonds, Adv. Mater. 31, 1808300, (2019).
45. S. Ohisa*, T. Takahashi, M. Igarashi, H. Fukuda, T. Hikichi, R. Komatsu, E. Ueki, Y.-J. Pu, T. Chiba, J. Kido*, An Indolocarbazole-Based Thermally Activated Delayed Fluorescence Host for Solution‐Processed Phosphorescent Tandem Organic Light-Emitting Devices Exhibiting Extremely Small Efficiency Roll-Off, Adv. Funct. Mater. 29, 1808022. (2019).
44. Y. Chikayasu, S. Ohisa*, T. Takahashi, T. Chiba, J. Kido*, ZnO/Polyethyleneimine Ethoxylated/Lithium Bis(trifluoromethanesulfonyl)imide for Solution-Processed Electron Injection Layers in Organic Light-Emitting Devices, J. Photopolym. Sci. Tec. 32, 577 (2019).
2018
43. T. Chiba*, Y. Hayashi, H. Ebe, K. Hoshi, J. Sato, S. Sato, Y.-J. Pu, S. Ohisa, J. Kido*, Anion-exchange red perovskite quantum dots with ammonium-iodine salts for highly efficient light-emitting devices, Nat. Photon. 12, 681–687 (2018). [Top 1% as a highly cited paper]
42. T. Chiba*, D. Kumagai, K. Udagawa, Y. Watanabe, J. Kido*, Dual mode OPV-OLED device with photovoltaic and light-emitting functionalities, Sci. Rep. 8. 11472 (2018). [Top 100 in Physics 2018]
41. K. Hoshi, T. Chiba*, J. Sato, Y. Hayashi, Y. Takahashi, H. Ebe, S. Ohisa, J. Kido*, Purification of Perovskite Quantum Dots Using Low-Dielectric-Constant Washing Solvent “Diglyme” for Highly Efficient Light-Emitting Devices, ACS Appl. Mater. Interfaces 10, 24607-24612 (2018).
40. T. Chiba* J. Kido*, Lead halide perovskite quantum dots for light-emitting devices, J. Mater. Chem. C 6, 11868-11877 (2018).
39. H. Ebe, Y. Takahashi, J. Sato, T. Chiba*, S. Ohisa, J. Kido*, Interfacial Engineering of Perovskite Quantum-Dot Light-Emitting Devices Using Alkyl Ammonium Salt Layer. J. Photopolym. Sci. Tec. 31, 329 (2018).
38. T. Iino, S. Mori, K. Shito, A. Kimura, Y. Morishita, T. Chiba, H. Katagiri, S. Okada, A. Masuhara, Fabrication and characterization of dichroic fine crystals by the reprecipitation method, Appl. Phys. Express 11, 065001, (2018).
37. S. Ohisa, T. Kato, T. Takahashi, M. Suzuki, Y. Hayashi, T. Koganezawa, C. R. McNeill, T. Chiba, Y. J. Pu, J. Kido, Conjugated Polyelectrolyte Blend with Polyethyleneimine Ethoxylated for Thickness-Insensitive Electron Injection Layers in Organic Light-Emitting Devices, ACS Appl. Mater. Interfaces 10, 17318-17326, (2018).
36. S. Sato, S. Ohisa*, Y. Hayashi, R. Sato, D. Yokoyama, T. Kato, M. Suzuki, T. Chiba, Y. J. Pu, J. Kido*, Air-Stable and High-Performance Solution-Processed Organic Light-Emitting Devices Based on Hydrophobic Polymeric Ionic Liquid Carrier-Injection Layers. Adv. Mater. 30, 1705915, (2018).
35. S. Ohisa, K. Endo, K. Kasuga, M. Suzuki, T. Chiba, Y. J. Pu, J. Kido, Post-Treatment-Free Solution-Processed Reduced Phosphomolybdic Acid Containing Molybdenum Oxide Units for Efficient Hole-Injection Layers in Organic Light-Emitting Devices, Inorg. Chem. 57, 1950 (2018).
34. S. Ohisa, K. Kasuga, K. Endo, Y.-J. Pu, T. Chiba J. Kido, Operation behaviors of interconnecting-layers in solution-processed tandem organic light-emitting devices, Org. Electron. 63, 98-103 (2018).
33. S. Ohisa, T. Hikichi, Y.-J. Pu, T. Chiba, J. Kido, Two-Dimensional Ca2Nb3O10 Perovskite Nanosheets for Electron Injection Layers in Organic Light-Emitting Devices, ACS Appl. Mater. Interfaces 10, 27885-27893 (2018).
32. K. Umemoto, M Takeda, Y. Tezuka, T. Chiba, M. S.White, T. Inose, T. Yoshida, S. Asakura, S. Toyouchi, H. Uji-I, A. Masuhara, Separation of mono-dispersed CH3NH3PbBr3 perovskite quantum dots via dissolution of nanocrystals, Cryst. Eng. Comm. 20, 7053-7057 (2018).
2017
31. T. Chiba, Y.-J. Pu*, T. Ide, S. Ohisa, H. Fukuda, T. Hikichi, D. Takashima, T. Takahashi, S. Kawata, J. Kido*, Addition of Lithium 8-Quinolate into Polyethylenimine Electron-Injection Layer in OLEDs: Not Only Reducing Driving Voltage but Also Improving Device Lifetime, ACS Appl. Mater. Interfaces 9, 10, 17318-17326 (2017).
30. T. Chiba*, K. Hoshi, Y.-J. Pu, Y. Takeda, Y. Hayashi, S. Ohisa, S. Kawata, J. Kido*, High-Efficiency Perovskite Quantum-Dot Light-Emitting Devices by Effective Washing Process and Interfacial Energy Level Alignment, ACS Appl. Mater. Interfaces 9, 18054-18060 (2017).
29. S. Ohisa, Y.-J. Pu, S. Takahashi, T. Chiba, J. Kido, Inhibition of solution-processed 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile crystallization by mixing additives for hole injection layers in organic light-emitting devices, Polymer J. 49, 149-154, (2017)
28. S. Ohisa, T. Hikichi, Y. J. Pu, T. Kato, T. Takahashi, T. Chiba, J. Kido, Surface-Modified Zinc Oxide Nanoparticles for Electron Injection Layers in Organic Light-Emitting Devices. J. Photopolym. Sci. Tec. 30, 483 (2017).
2016
27. S. Ohisa, S. Kagami, Y.-J. Pu, T. Chiba J. Kido, A Solution-Processed Heteropoly Acid Containing MoO3 Units as a Hole-Injection Material for Highly Stable Organic Light-Emitting Devices, ACS Appl. Mater. Interfaces 8, 20946–20954, (2016).
26. T. Chiba*, Solution-Processed Tandem Organic Light-Emitting Devices, Kobunshi Ronbunshu, 73, 464-474, (2016).
25. T. Chiba, A. Fukada, M. Igarashi, S. Ohisa, Y.-J. Pu*, J. Kido*, A Solution-Processable Small-Molecule Host for Phosphorescent Organic Light-Emitting Devices, J. Photopolym. Sci. Tec. 29, 317-321, (2016).
24. T. Chiba, Y.-J. Pu*, J. Kido*, Organic Light-Emitting Devices with Tandem Structure, Top. Curr, Chem. 374(3), 1-17, (2016)
2015
23. T. Chiba, Y.-J. Pu, J. Kido, Solution-Processed White Phosphorescent Tandem Organic Light-Emitting Devices, Adv. Mater. 27, 4681-4687, (2015).
22. Y.-J. Pu, T. Chiba K. Ideta, S. Takahashi, N. Aizawa, T. Hikichi, J. Kido, Fabrication of Organic Light‐Emitting Devices Comprising Stacked Light‐Emitting Units by Solution‐Based Processes, Adv. Mater. 27, 1327-1332, (2015).
21. T. Chiba, Y.-J. Pu*, J. Kido*, Solution-Processable Electron Injection Materials for Organic Light-Emitting Devices, J. Mater. Chem. C 3, 11567-11576 (2015).
20. Y.-J. Pu, N. Morishita, T. Chiba, S. Ohisa, M. Igarashi, A. Masuhara, J. Kido, Efficient Electron Injection by Size- and Shape-Controlled Zinc Oxide Nanoparticles in Organic Light Emitting Devices, ACS Appl. Mater. Interfaces 7, 25373-26377, (2015).
19. C. H. Jun, S. Ohisa, Y.-J. Pu, T. Chiba J. Kido, Comparison of Spin and Blade Coating Methods in Solution-process for Organic Light-emitting Devices, J. Photopolym. Sci. Tec. 28, 343-347, (2015).
2014
18. T. Chiba, Y.-J. Pu, S. Takahashi, H. Sasabe, J. Kido, Lithium Phenolate Complexes with a Pyridine-Containing Polymer for Solution-Processable Electron Injection Layers in PLEDs, Adv. Funct. Mater. 24, 6038-6045, (2014).
17. N. Aizawa, Y.-J. Pu, M. Watanabe, T. Chiba, K. Ideta, N. Toyota, M. Igarashi, Y. Suzuri, H. Sasabe, J. Kido, Solution-processed multilayer small-molecule light-emitting devices with high-efficiency white-light emission, Nat. Commun. 5, 5756, (2014).
16. N. Aizawa, Y.-J. Pu, T. Chiba, S. Kawata, H. Sasabe, J. Kido, Instant Low-Temperature Cross-Linking of Poly(N-vinylcarbazole) for Solution-Processed Multilayer Blue Phosphorescent Organic Light-Emitting Devices, Adv. Mater. 26, 7543-7546, (2014).
15. C. H. Jun, Y.-J. Pu, M. Igarashi, T. Chiba, H. Sasabe, J. Kido, A Donor–Acceptor-type Host Material for Solution-processed Phosphorescent Organic Light-emitting Devices Showing High Efficiency, Chem. Lett. 43, 1935-1936, (2014).
2013
14. Y.-J. Pu, T. Chiba, N. Aizawa, H. Sasabe, J. Kido, Multilayered Organic Light-Emitting Devices by Solution-Process, J. Photopolym. Sci. Tec. 26, 403-410, (2013).
2012
13. T. Chiba, Y.-J. Pu, H. Sasabe, J. Kido, Y. Yang, Solution-processed organic light-emitting devices with two polymer light-emitting units connected in series by a charge-generation layer, J. Mater. Chem. 22, 22769-22773, (2012).
12. T. Chiba, Y.-J. Pu, M. Hirasawa, A. Masuhara, H. Sasabe, J. Kido, Solution-Processed Inorganic-Organic Hybrid Electron Injection Layer for Polymer Light-Emitting Devices, ACS Appl. Mater. Interfaces 4, 6104-6108, (2012).
11. 61 S. Inayama, N. Takahashi, Y.-J. Pu, T. Chiba, H. Sasabe, J. Kido, Syntheses of Solution-Processable Arylamine Derivatives and Their Application to Organic Light Emitting Devices, J. Photopolym. Sci. Tec. 25, 335-339, (2012).
2011
10. T. Chiba, Y.-J. Pu, R. Miyazaki, K. Nakayama, H. Sasabe, J. Kido, Ultrahigh efficiency by multiple emission from stacked organic light-emitting devices, Org. Electron. 12, 710-715, (2011).
9. T. Chiba, K. Nakayama, Y.-J. Pu, T. Nishina, M. Yokoyama, J. Kido, Hole mobility measurement of 4,4’Bis[N-(1-naphthyl)-N-phenylamino]-biphenyl by dark injection method, Chem. Phys. Lett. 502, 118-120, (2011).
8. H. Sasabe, D. Tanaka, D. Yokoyama, T. Chiba, Y.-J. Pu, K. Nakayama, M. Yokoyama, J. Kido, Influence of Substituted Pyridine Rings on Physical Properties and Electron Mobilities of 2-Methylpyrimidine Skeleton-Based Electron Transporters, Adv. Funct. Mater. 21, 336-342, (2011).
7. C. Cai, S. J. Su, T. Chiba, H. Sasabe, Y.-J. Pu, K. Nakayama, J. Kido, High-efficiency red, green and blue phosphorescent homojunction organic light-emitting diodes based on bipolar host materials, Org. Electron. 12, 843-850, (2011).
6. C. Cai, S. J. Su, T. Chiba, H. Sasabe, Y.-J. Pu, K. Nakayama, J. Kido, Efficient Low-Driving-Voltage Blue Phosphorescent Homojunction Organic Light-Emitting Devices, Jpn. J. Appl. Phys. 50, 040204, (2011).
2009
5. S. J. Su, Y. Takahashi, T. Chiba, T. Takeda, J. Kido, Structure–Property Relationship of Pyridine-Containing Triphenyl Benzene Electron-Transport Materials for Highly Efficient Blue Phosphorescent OLEDs, Adv. Funct, Mater. 19, 1260-1267, (2009).
2008
4. S. J. Su, T. Chiba, T. Takeda, J. Kido, Pyridine‐Containing Triphenylbenzene Derivatives with High Electron Mobility for Highly Efficient Phosphorescent OLEDs, Adv. Mater. 20, 2125-2130 (2008).
3. H. Sasabe, T. Chiba, S. J. Su, Y.-J. Pu, K. I. Nakayama, J. Kido, 2-Phenylpyrimidine skeleton-based electron-transport materials for extremely efficient green organic light-emitting devices, Chem. Commun. 44, 5821-5823 (2008).
2. H. Sasabe, E. Gonmori, T. Chiba, Y. J. Li, D. Tanaka, S. J. Su, T. Takeda, Y.-J. Pu, K. I. Nakayama, J. Kido, Wide-Energy-Gap Electron-Transport Materials Containing 3,5-Dipyridylphenyl Moieties for an Ultra High Efficiency Blue Organic Light-Emitting Device, Chem. Mater. 20, 5951-5953, (2008).
2007
1. D. Tanaka, T. Takeda, T. Chiba, S. Watanabe, J. Kido, Novel Electron-transport Material Containing Boron Atom with a High Triplet Excited Energy Level, Chem. Lett. 36, 262-263 (2007).