學(xué)習(xí)和工作經(jīng)歷
1989.9 u2013 1993.7,廈門大學(xué)化學(xué)系,學(xué)士學(xué)位 物理化學(xué)專業(yè);
1993.9 u2013 1995.7,廈門大學(xué)化學(xué)系,碩士學(xué)位,物理化學(xué)專業(yè);
1995.9 u2013 1998.10,廈門大學(xué)化學(xué)系,博士學(xué)位,物理化學(xué)專業(yè);
1998.11 u2013 1999.2,廈大化學(xué)系,科研助手,物理化學(xué)專業(yè);
1999.3 u2013 2000.12,德國杜塞爾多夫大學(xué)表面和凝固態(tài)材料研究所(A. Otto教授),洪堡獎學(xué)金,博士后,利用衰減全內(nèi)反射拉曼光譜研究單晶銅表面物種的吸附,了解表面增強(qiáng)拉曼效應(yīng)和金屬表面粗糙度的關(guān)系;
2001.1 u2013 2001.12,慕尼黑工業(yè)大學(xué)物理系界面和能量轉(zhuǎn)換研究所(U. Stimming教授),博士后,開發(fā)、表征優(yōu)化氫氧燃料電池、直接甲醇燃料電池的膜電極列陣(Membrane Electrode Assemblies),以降低催化劑用量同時(shí)提高電池的效率,延長電池的壽命;
2002.1 u2013 2002.3,日本北海道大學(xué)催化研究中心界面和光譜電化學(xué)實(shí)驗(yàn)室(M. Osawa教授),日本北海道大學(xué)文部省中核機(jī)構(gòu)COE研究員,主要任務(wù):利用表面增強(qiáng)紅外光譜研究甲醇在鉑電極上的陽極氧化;
2002.4 u2013 2006.12,德國烏爾姆大學(xué)表面化學(xué)和催化研究所 (R. J. Behm教授) 博士后,電化學(xué)原位紅外光譜和電化學(xué)在線質(zhì)譜研究燃料電池相關(guān)的電催化反應(yīng);
2007.1 u2013 至今,中國科技大學(xué)化學(xué)物理系,合肥微尺度物質(zhì)科學(xué)國家實(shí)室,教授,博士生導(dǎo)師,譜學(xué)電化學(xué)在電催化中的應(yīng)用。
研究方向
表面電化學(xué)、光譜電化學(xué)和電催化,著重于電化學(xué)界面結(jié)構(gòu)、燃料電池以及生物電化學(xué)相關(guān)的電催化反應(yīng)機(jī)理和動力學(xué)的基礎(chǔ)研究以及相關(guān)研究技術(shù)的開發(fā)。
在研項(xiàng)目
1.面向車用燃料電池的納米-介觀-宏觀多級結(jié)構(gòu)的電催化體系的研究, 973 重大科學(xué)研究計(jì)劃子課題: 結(jié)構(gòu)明確的高活性電催化劑納米結(jié)構(gòu)基元的合成(編號2015CB932300,2014-2019)
2.Pt系單晶電極上氧還原反應(yīng)超電勢的起源研究, 國家自然基金面上項(xiàng)目 (編號:21473175, 2015-2018)
3. 等離子基元增強(qiáng)拉曼光譜儀器的研發(fā)與應(yīng)用子課題,PERS在電化學(xué)基礎(chǔ)研究中的應(yīng)用,國家重大科學(xué)儀器設(shè)備開發(fā)專項(xiàng)(編號:2011YQ03012416 2012-2016)
4. 電化學(xué)微分質(zhì)譜與紅外光譜聯(lián)用技術(shù)及其在燃料電池電催化中的應(yīng)用, 國家自然基金面上項(xiàng)目 (編號:21273215, 2013-2016)
已完成項(xiàng)目
1. 基于分子和分子體系的量子調(diào)控子課題,電極過程的量子調(diào)控, 973 重大科學(xué)研究計(jì)劃 (編號2010CB923302,2009-2014)
2.中國科技大學(xué)海外優(yōu)秀留學(xué)人才啟動基金(2007-2009)
3. 在可控的溫度及傳質(zhì)下甲醇氧化的電化學(xué)原位紅外光譜研究, 國家自然科學(xué)基金委面上項(xiàng)目(項(xiàng)目批準(zhǔn)號:20773116, 2008-2010)
4. 低鉑擔(dān)載甲醇氧化電催化劑結(jié)構(gòu)-性能關(guān)系研究, 德國洪堡基金會回國后續(xù)支持項(xiàng)目(2007-2009)
5. 用于甲醇陽極氧化的低維納米復(fù)合電催化劑的制備及性能表征, 廈門大學(xué)固體表面物理國家重點(diǎn)實(shí)驗(yàn)室開放課題 (2008-2009)
6. 中國科院百人計(jì)劃(2009-2011)
7. 石墨烯上金屬鈉米粒子的構(gòu)筑及其電催化活性研究, 廈門大學(xué)固體表面物理國家重點(diǎn)實(shí)驗(yàn)室開放課題(2010-2011)
8. 譜學(xué)電化學(xué)在電催化中的應(yīng)用, 教育部留學(xué)回國人員啟動基金(2010-2012)
9. 鉑基氧還原催化劑性能改善機(jī)理研究, 國家自然科學(xué)基金委面上項(xiàng)目(項(xiàng)目批準(zhǔn)號:21073176,2011-2013).
獲獎情況
1. 電化學(xué)青年獎, 中國電化學(xué)會,2011.10
2. 青年研究獎學(xué)金,德國洪堡基金會, 1999. 7- 2000.12, 2002.7-2002.9
3. 日本文部省COE獎學(xué)金
4. 中科院”百人計(jì)劃”擇優(yōu)支持
5. 日本北海道大學(xué)訪問教授
發(fā)表的學(xué)術(shù)論文及專著
Papers published in 2014
1.The Effect of Alcohol Concentration on the Mass Signal of CO2 Detected by Differential Mass Spectrometry
Wei Chen; Qian Tao; Jun Cai; Yan Xia Chen
Electrochemistry Communications, 2014,48,10.
2.On the Origin of the Errors of ik as Estimated from K-L Equation in Rotating Disk Electrode System
Wei Chen; Lingwen Liao; Zhengda He; Yanxia Chen
Journal of Electrochemistry
3.The Preparation of Surfactant-free Pt and PtRu Nanoparticles with high Activity for Methanol Oxidation
Yao Yao, Jun Cai, Yong Li Zheng, Yan-Xia Chen
Chinese Journal Of Chemical Physics, 2014
4.Methanol Oxidation at Pt and PtRu Electrodes, a Study by Combined in-situ Infrared Spectroscopy and Differential Electrochemical Mass Spectrometry (Acceped)
Qian Tao, Wei Chen, Yao Yao, Ammar Bin Yousaf ,Yan-Xia Chen
Chinese Journal Of Chemical Physics, 2014
5.A Kinetics Study on O2 Adsorption and OHad Desorption at Pt(111), Its Implication to Oxygen Reduction Reaction Kinetics (Acceped)
Fan Yang,Ling Wen Liao,Ming Fang Li,Dong Mei,Yan-Xia Chen
Chinese Journal Of Chemical Physics, 2014
6.Mechanistic and Kinetic Implications on ORR at Au(100) Electrode, pH, Temperature and H-D kinetic Isotope effects
D. Mei, Z. D. He, Y. L. Zheng, D. C. Jiang, Y.-X. Chen
Phys. Chem. Chem. Phys, DOI:10.1039/C4CP00257A
7.Redox Reaction of Hydrogen Peroxide at Au(100) Electrode, Its Implication to Oxygen Reduction Kinetics
Zheng, Y; Mei, D; Chen, Y; Ye, S.
Electrochem. Commun,2014, 39,19.
8.Interaction of C1 Molecules with a Pt Electrode at Open Circuit Potential: A Combined Infrared and Mass Spectroscopic Study
Q. Tao, Y.-L. Zheng, D.-C. Jiang, Y.-X. Chen,Z. Jusys and R. J. Behm
J. Phys. Chem. C, 2014, 118, 6799
9.Electrodeposition of silver on stepped platinum electrode surfaces with (100)-oriented terraces: Generation of confined reaction sites
J. Xu, A.-E.-Aziz, A. A.-E.l-Latif, Y.-X. Chen, H. Baltruschat
J. Electroanal. Chem.,2014, 716, 93
10.Modeling of the Potential Oscillation during Galvanostatic Electrooxidation of Formic Acid at Platinum Electrode
Dong Mei, Zheng-Da He, Dao Chuan Jiang, Jun Cai and Yan-Xia Chen
J. Phys. Chem. C, 2014,118,6335.
11.甲醇及甲酸在模型單晶鉑電極上電催化氧化機(jī)理及動力學(xué)的研究
徐杰, 江道傳,梅東, 何政達(dá),陳艷霞
電化學(xué)
Papers published in 2013
1.Kinetic Implication from Temperature effect on Hydrogen Evolution Reaction at Ag Electrode
Jing Kang, Chu-Hong Lin, Yao Yao and Yan-Xia Chen
Chinese Journal Of Chemical Physics, 2013.27.63
2.鉑基催化劑上的氧還原
李明芳, 廖鈴文, 楊帆, 姚瑤, 陳艷霞
電催化, 化工出版社, 第7章, 2013
3.Potential Dependence of Cyanide Adsorption at Pt Electrode in Acidic Solution: An Electrochemical in-situ Infrared Spectroscopic Study
Shao Xiong Liu, Yong Li Zheng, Jie Xu, Jun Cai, Wen Hua Zhang, Jin Long Yang, Yan Xia Chen*
J. Physical Chemistry C, 2013, 117, 15562.
4.pH Effect on Oxygen Reduction Reaction at Pt(111) Electrode
Ming Fang Li, Ling Wen Liao,Dao Fu Yuan, Dong Mei, Yan-Xia Chen*
Electrochim. Acta, 2013,110,780.
5.On the Mechanism of the Direct Pathway for Formic Acid Oxidation at Pt(111) Electrode
J. Xu, D.F. Yuan, F.Yang, D. Mei, Z. B. Zhang and Y. X. Chen
Phys. Chem. Chem. Phys., 2013, 15 (12), 4367.
6.Density functional theory study on the adsorption and decomposition of the formic acid catalyzed by highly active mushroom-like Au@Pd@Pt tri-metallic nanoparticles
S. Duan,Y.-F. Ji,P.-P. Fang,Y. X. Chen,X. Xu,Y. Luoand Z.-Q. Tian
Phys. Chem. Chem. Phys., 2013, 15 (13), 4625.
7.Electrode Reaction Induced pH change at the Pt Electrode/Electrolyte Interface and its Impact on Electrode Processes
L. W. Liao, M. F. Li, J. Kang, D. Chen, Y. X. Chen and S. Ye
J. Electroanal. Chem. 2013, 688, 207.
8.The Effect of Catalyst Loading on the Evaluation of Kinetic Parameters of Gas Electrode Reactions using Thin Film Rotating Disk Electrode Method
L. W. Liao, D. Chen, M. F. Li, Y. L. Zheng, J. Kang, Y. X. Chen,
SCIENTIA SINICA Chimica, 2013,43,178.
9.A Revisit to the Role of Bridge-adsorbed Formate in the Electrocatalytic Oxidation of Formic Acid at Pt Electrodes
J. Xu; D. Mei; D. F. Yuan; Z. B. Zhang; S. X. Liu; Y. X. Chen
Chinese Journal Of Chemical Physics, 2013, 26(3), 321.
10.The Role of Bridge-bonded Formate in Formic acid Dehydration to CO at Pt Electrode: An Electrochemial in situ Infrared Spectroscopic Study
Z. B. Zhang, J.Xu, J. Kang and Y. X. Chen,
Chinese Journal Of Chemical Physics, 2013, 26(4),471.
11.Oxygen Reduction Reaction on Glycin Modified Pt(111) Electrode
M. F. Li, J. Kang, L. W. Liao, Y. X. Chen and S. Ye
Journal of Electrochemistry, 2013, 19, 1.
12.Determination of the Isotherm for Acetate and Formate Adsorption at Pt(111) Electrode by Fast Scan Voltammetry
J. Xu, C.H. Lin, D. Mei, Z. B. Zhang, D. F. Yuan and Y. X. Chen
Chinese Journal Of Chemical Physics, 2013,26(2),191.
Papers published in 2012
1.Temperature Effect on Hydrogen Evolution Reaction at Au Electrode
Z. Q. Tang; L. W. Liao; Y. L. Zheng; J. Kang; Y. X. Chen
Chinese Journal Of Chemical Physics, 2012, 25,469.
2.Control over the branched structures of platinum nanocrystals for electrocatalytic applications
L. Ma,C. M. Wang,M. Gong, L. W. Liao, R. Long, J. G. Wang, D. Wu, W. Zhong, M. J. Kim, Y. X. Chen,Y. Xie, and Y. J. Xiong,
ACS Nano, 2012, 69797.
3.Polyoxometalates Immobilized in Ordered Mesoporous Carbon Nitride as Highly Efficient Water Oxidation Catalysts
J. Wu, L. W. Liao, W. S. Yan, Y. Xue, Y. F. Sun, X. Yan, Y. X. Chen, and Y. Xie,
ChemSusChem,2012, 5,1207.
Papers published in 2011
1.The Kinetics of CO Pathway in Methanol Oxidation at Pt Electrodes, a Quantitative Study by ATR-FTIR Spectroscopy
L.W. Liao, S. X. Liu, Q. Tiao, B. Geng,P. Zhang, C. M. Wang, Y.-X. Chen and S. Ye,
Phys.Chem. Chem. Phys., 2011, 13, 9725.
2.A method for kinetic study of methanol oxidation at Pt electrodes by electrochemical in situ infrared spectroscopy
L.W. Liao, S. X. Liu, Q. Tiao, B. Geng,P. Zhang, C. M. Wang, Y.-X. Chen and S. Ye,
J. Electroanal. Chem., 2011, 650, 233.
3.Determining the Active Surface Area of Various Pt Electrodes with Different Roughness and Dispersion
Dong Chen, Qian Tao, Ling Wen Liao, Shao Xiong Liu, Yan-Xia Chen and Shen Ye,
Electrocatalysis, 2011.2.207
4.室溫下Pt電極上CO的脫附機(jī)理研究
劉少雄, 康婧, 耿斌, 陶騫, 陳艷霞
中國科學(xué),化學(xué),2011, 41, 1582.
5.不同pH值下多晶Au電極上的氧還原反應(yīng)
中國科學(xué),化學(xué), 2011,41, 1777.
6.Pd/Pt二元合金電極的制備及其氧還原性能研究
方蘭蘭,廖玲文, 劉少雄, 蔡俊, 李明芳, 陳艷霞
高等學(xué);瘜W(xué)學(xué)報(bào), 2011,32, 1144.
7.Electrochemistry of ABTS at Glassy Carbon Electrodes
Han Zeng, Zhi-qiang Tang, Ling-wen Liao, Jing Kang, Yan-xia Chen
Chinese J. Chemical Physics, 2011, 24, 653.
Papers published before 2011
1. Temperature effects on CO Adsorption/Desorption at Pt Film Electrodes: An Electrochemical in-situ Infrared Spectroscopic Study
B. Geng, J. Cai, S. Liang, S. X. Liu, M.F. Li and Y.-X. Chen,
Phys. Chem. Chem. Phys., 2010, 12, 10888 - 10895
2. Potential-Dependent Chemisorption of Carbon Monoxide at a Gold Core―Platinum Shell Nanoparticle Electrode: A Combined Study by Electrochemical in situ Surface-Enhanced Raman Spectroscopy and Density Functional Theory
Pu Zhang, Jun Cai, Yan-Xia Chen, Zhi-Qiang Tang, Dong Chen, JinLong Yang,De-Yin Wu, Bin Ren and Zhong-Qun Tian,
J. Phys. Chem. C, 2010, 114, 403u2013411
3. Oxidation of Carbon Supports at Fuel Cell Cathodes: Differential Electrochemical Mass Spectrometric Study
M.F. Li, Q. Tao, L. W. Liao, J. Xu, J. Cai and Y. X. Chen,
Chinese J. Chemical Physics, 2010, 4, 442-446
4. Determination of the Real Surface Area of Palladium Electrode
L.-L. Fang, Q. Tao, M.-F. Li, L.-W. Liao, D. Chen and Y.-X. Chen,
Chinese J. Chemical Physics, 2010, 5, 543.
5. 聚芳酰胺-多壁碳納米管混合物固定漆酶電極的電化學(xué)行為
曾涵,廖鈴文,李明芳,陶騫,康婧,陳艷霞,
物理化學(xué)學(xué)報(bào),2010, 26, 3217。
6. Pt電極上CO的同位素取代吸附機(jī)理研究
梁桑梓,劉少雄,廖玲文,陶騫,康婧,陳艷霞,
電化學(xué),2010,16,324
7. Temperature Programmed Desorption u2013 An Application to Kinetic Studies of CO Desorption at Electrochemical Interfaces
Bin Geng, Jun Cai, Shao-Xiong Liu, Pu Zhang, Zhi-Qiang Tang, Dong Chen, Qian Tao,Yan-Xia Chen and Shou-Zhong Zou,
J. Phys. Chem. C, 2009, 113, 20152u201320155.
8. An Electrochemical in Situ Surface-Enhanced Raman Spectroscopic Study of Carbon Monoxide Chemisorption at a Gold Core-Platinum Shell Nanoparticle Electrode with a Flow Cell
Pu Zhang, Yan-Xia Chen, Jun Cai, Sang-Zi Liang, Jian-Feng Li, An Wang, Bin Ren and Zhong-Qun Tian
J. Phys. Chem. C, 2009,113(40): 17518-17526.
9. The Mechanism and Kinetics of Cyanide-Assisted CO Desorption from Pt Electrodes: an Infrared Spectroscopic Study
Bin Geng, Shaoxiong Liu, Jun Cai, Sangzi Liang, and Yan-Xia Chen,
J. Phys. Chem. C, 2009, 113, 10326.
10. A Thermostatic Cell with Gas Diffusion Electrode for Oxygen Reduction Reaction under Fuel Cell Relevant Conditions
Yan-Xia Chen, Ming-Fang Li, Ling-Wen Liao, Jie Xu, Shen Ye,
Electrochem. Commun., 2009,11,1434
11. Potential-Induced COad Island Formation on a Platinum Thin-Film Electrode in the H-upd Potential Region
Yan-Xia Chen, Martin Heinen, Zenonas Jusys, and Rolf Juergen Behm,
J. Phys. Chem. C, 2007, 111, 435.
12. Kinetic Isotope Effects in Complex Reaction Networks: Formic Acid Electro-Oxidation
Yan-Xia Chen, Martin Heinen, Zenonas Jusys, and Rolf Juergen Behm,
ChemPhysChem, 2007, 8, 380 u2013 385.
13. Room Temperature COad Desorption/Exchange Kinetics on Pt Electrodes—A Combined In Situ IR and Mass Spectrometry Study
Martin Heinen, Yan-Xia Chen, Zenonas Jusys, and Rolf Juergen Behm,
ChemPhysChem, 2007, 8, 2484 u2013 2489.
14. CO adsorption kinetics and adlayer build-up studied by combined ATR-FTIR spectroscopy and on-line DEMS under continuous flow conditions
Martin Heinen, Yan-Xia Chen, Zenonas Jusys, and Rolf Juergen Behm,
Electrochmica Acta, 2007, 53,1279.
15. In situ ATR-FTIRS coupled with on-line DEMS under controlled mass transport conditions—A novel tool for electrocatalytic reaction studies
Martin Heinen, Yan-Xia Chen, Zenonas Jusys, and Rolf Juergen Behm,
Electrochmica Acta, 2007, 52,5634
16. Kinetics and Mechanism of Formic Acid Electrooxidation u2013 Spectro-Electrochemical Studies in a Novel Flow Cell Configuration,
Yan-Xia Chen, Martin Heinen, Zenonas Jusys, and Rolf Juergen Behm,
Angewandte Chemie, Int. Edition, 2006, 45, 981.
17. Bridge-Bonded Formate: Activeintermediate or Spectator Species in Formic Acid Oxidation on a Pt Film Electrode
Yan-Xia Chen, Martin Heinen, Zenonas Jusys, and Rolf Juergen Behm,
Langmuir, 2006, 22, 10399.
18. Application of in-situ Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy for the Understanding of Complex Reaction Mechanism and Kinetics: Formic Acid Oxidation on a Pt Film Electrode at Elevated Temperatures,
Yan-Xia Chen, Martin Heinen, Zenonas Jusys, and Rolf Juergen Behm,
J. Phys. Chem. B, 2006 110(19): 9534-9544.
19. Electronic effects in SERS by liquid water
Yan-Xia Chen and Andreas Otto,
J. Raman Spectrosc., 2005, 36, 736.
20. CO2 reduction on Pt electrocatalysts and its impact on H2 oxidation in CO2 containing fuel cell feed gas - A combined in-situ infrared spectroscopy, mass spectrometry and fuel cell performance study
Smolinka T., Heinen M., Chen Y.X., Jusys Z., Lehnert W., and Behm R.J.,
Electrochimica Acta, 2005, 50, 5189.
21. Formate, an Active Intermediate for Direct Oxidation of Methanol on Pt Electrode.
Chen Y. X., Miki A., Ye S.,Sakai H. and Osawa M.:
Journal of American Chemical Society, 125 (2003), 3680.
22. On the "chloride activation" in SERS and single molecule SERS.
Otto A., Bruckbauer A., Chen Y. X.,
Journal of Molecular Structure, 2003, 662, 501.
23. The charge transfer effect of SERS induced by the electrochemical hydrogen evolution reaction.
F. M. Liu; Q. Han; Y. X. Chen; Q. L. Zhong; B. Ren; Z. Q. Tian,
Electrochemistry, 2001, 7(1), 74-77.
24. SERS studies of Electrode/electrolyte interfacial water II. Librations of water and electrochemical hydrogen evolution reaction
Chen Y. X., Zou S. Z., Huang K. Q. and Tian Z. Q.,
Journal of Raman Spectroscopy, 1998,249,749.
25. In Situ Raman Spectroscopic Study of the Oxidation and Reduction of Ag Electrode in Na2SO4 solution.
Chen Y. X., Huang K. Q. and Tian Z. Q.:
Electrochemistry,1998,4(2) 135.
26. SERS studies on electrode/electrolyte interfacial water---I. Ion effects in the negative potential region
Zou S. Z., Chen Y. X., Mao B.W., Ren B. and Tian Z. Q.:
Journal of Electroanalytical Chemistry,1997,24, 19-25.
27. Extending ECSTM Studies to Polycrystalline Electrode Surfaces with Atomic Resolution.
Shi C. H., Cai X. W., Chen Y. X., Tian Z. Q. and Mao B. W.:
Acta Physico-Chimica Sinica, 1997,13(12) 1061-1064
28. SERS Studies of Electrode/Electrolyte Interfaces I. Cu/1.0 M Na2SO4 and NaCl solution.
Chen Y. X., Huang K. Q. and Tian Z. Q.:
Chinese Journal of Light Scattering,1997,9(2-3), 289-291.
29. SERS Studies of Electrode/Electrolyte Interfaces II. Ag/MgSO4 System? A Possible Method Measuring Interfacial pH.
Chen Y. X., Huang K. Q. and Tian Z. Q.:
Chinese Journal of Light Scattering,1997,9(2-3), 292-294
30. Dependence of Surface-enhanced Raman scattering of water on the hydrogen evolution reaction,
Chen Y. X. and Tian Z. Q.:
Chemical Physical Letters, 1997,281,379.
31. Raman spectroscopic studies of water in different electrolyte solutions.
Zou S. Z., Chen Y. X., Zhang Y. H., , Tian Z. Q. :
Acta Physico-Chimica Sinica 1996,12 (2) 130-135.
32. Probing electrode/electrolyte interfacial structure in the potential region of hydrogen evolution by Raman spectroscopy.
Tian Z. Q., Ren B., Chen Y. X., Zou S. Z. and Mao B. W.:
Journal of Chemistry Society, Faraday Transactions ,1996,92(20) 3829-3838.
33. SERS studies of the structure and orientation of water over Ag electrode---the effects of electrode potentials and electrolyte concentration.
Zou S. Z., Zhang Y. H., Chen Y. X., Tian Z. Q.:
Chemical Journal of Chinese Universities 1995,16 (2), 245-251.
34. SERS effect induced from conducting Polymer/Solution Interfaces.
Gao J. S., Chen Y. X., Tian Z. Q., Li C. Z., Liu Z. F. and Cai S. M.:
Electrochemistry 1995, 1(2), 237-247.
35. Extending surface-enhanced Raman spectroscopic studies on water at gold electrodes.
Tian Z. Q., Chen Y. X., Mao B. W., Li C. Z., Wang J. and Liu Z. F.
Chemical Physical Letters, 1995, 240, 224-229.