Physics in Zhejiang University

(Published in AAPPS 2002, revised 2003)

I. Zhejiang University

     Hangzhou, a beautiful and prosperous city honored as “paradise on earth”, is located in China’s east coast. As a city with world fame, Hangzhou enjoys a mild climate throughout the year, trees making a pleasant shade and green hills embracing the city. West Lake is known as the symbol of Hangzhou, and the humanistic and historic sites all around add strong cultural color to the city.
      Zhejiang University sits beside West Lake. Founded in 1897 and grew out of the Qiu-shi School, it is one of the several universities with a history of more than 100 years in China. It’s the long history and rigorous scholarship that cultivate 76 academicians of Chinese Academy of Sciences and Academy of Engineering within its graduates. What’s more, there have been 138 academicians among the alumnae and alumni of Zhejiang University.
     Many notable scholars like Ke-zheng Zhu (Ko-chen Chu), Yin-chu Ma, Jia-xi Lu, Bu-qing Shu, Shan-qiang Qian, Gang-chang Wang, Shi-zhang Bei, Jian-gong Chen, Ling-xi Qian, Jia-zhen Tan, Hao-chao Gu, Xiao-cang Zheng, Shou-pan Liang, Chen-tao Xia, Liang-fu Jiang, Zheng-dao Li (T.D. Lee), Jian-xiong Wu, Xian-tu He and Yong-xiang Lu all have been teaching and studying in Zhejiang University. Zhejiang University is a cradle of science masters.
     Ko-chen Chu, a famous scientist and educationist who had contributed greatly to meteorology, geography, agricultural development and resource utility, assumed the office of the president of Zhejiang University from 1936 to 1949. He advocated democracy and the academic style of pursing the truth, and significantly developed Zhejiang University from a small local university to a national one with world fame. When the well-known British scholar, Prof. Joseph Lee, visited China, he was surprised by the rapid progress of Zhejiang University, praising it as “Cambridge University in the East”.
     In 1952, Zhejiang University shrank to a university majoring in technology due to the reconstruction of universities in China. Yong-xiang Lu, the present Chairman of Chinese Academy of Science, had been the president of Zhejiang University from 1988 to 1995. During that period of time, he had been keen on education reforms, innovated the new system of management, and greatly promoted the development of all subjects and enhanced the comprehensive strength of Zhejiang University. In 1998, Zhejiang University took the lead in universities and colleges re-combination in China and turned itself into a comprehensive research university with the widest range of subjects. Zhejiang University is among the first-class in China’s Universities and gains its reputation in the world. 
     In Zhejiang University are there now 24 national key subjects, 11 national key labs, 2 national engineering research centers, 3 national engineering and technology research centers, 1000 professors and 2400 associate professors, 20 Guangbiao distinguished professors, 25 distinguished professors, more than 40,000 students, among whom are over 11,000 graduate students as well as more than 480 foreign ones. Besides, the number of the academicians of Chinese Academy of Sciences and Academy of Engineering has increased to 17 compared with none in 1990. In the recent years, comprehensive strength, research funds and the scientific publications of Zhejiang University rank stably in the top five among China’s universities.

II. Physics Department


    Physics Department in Zhejiang University was founded in 1929. Having experienced several years’ frustration, however, by the end of 1930’s, compared with the other universities in China, the Physics Department in Zhejiang University had had a strong faculty consisting of scholars like Gang-fu Hu, Shao-zhong Zhang, Zen-lu He, Xing-bei Shu and Gang-chang Wang. Meanwhile, its labs were well equipped and it preserved American journals like “Physical Review”, “Review of Modern Physics” as well as important German and British physics journals. All these above had created favorable ambience and provided the basis for physics research.
    From 1933 to 1935, Prof. Jian-xiong Wu held teaching post in Zhejiang University, while T.D. Lee spent 4 years studying in Zhejiang University from 1943 to 1946. By the end of 1950’s, 13 academicians of Chinese Academy of Science had been teaching or studying in the Physics Department of Zhejiang University successively like Gang-chang Wang, Gong-xu Gu, Kai-jia Cheng, Ji-ming Hu, Ning Nu, Ming Lu, Zhi-jian Li and Xian-tu He.
     Prof. Gang-chang Wang, a famous physicist, had been working in Zhejiang University for 14 years from 1936 to 1950. At the beginning of 1940’s, Prof. Wang put forward that it is feasible to prove the existence of neutrino in the process that by capturing a k-th shell electron, Beryllium nucleon decays to Lithium and a neutrino. The article was published on “Physical Review” in 1942, and the result was confirmed by experiment several months later. This conclusion provided a solid basis for the Fermi theory and was considered as a significant progress of physics in the world in 1942. In the 1950’s, Prof. Wang went to Dubna Nuclear Center in Soviet Union for scientific research. In 1960, his discovery of the particle  made him a physics master.
    The Physics Department was disbanded in the reconstruction of China’s universities in the summer of 1952, when Prof. Gang-chang Wang was assigned to Beijing, and it was reestablished in 1957.
  In 1981, Profs. Wen-zhu Li and Rong Wang were approved by the State Education Commission to be in the first list of thesis advisors of doctoral students in China. In the following ten years, quite some excellent doctorial students graduated and made progress in lattice gauge theory and mathematical physics. In 1982, the second national annual meeting of Chinese high energy physics was held in Zhejiang University.
    In 1988, Prof. Qi-rui Zhang joined the Physics Department in Zhejiang University. He was accomplished in the research like the substitution effect and flux pinning in type-II superconductors, and had played a substantial role in the establishment of the Institute for Condensed Matter Physics.
    In 1991, in order to promote the development of physics in Zhejiang University, Zhejiang Institute of Modern Physics was established under the support of Profs. T.D. Lee and Yong-xiang Lu, who was the president of the University then. Prof. T.D. Lee took the chair of the Institute. The Institute has been attracting many excellent doctors to do their postdoctoral research there. The young researchers assembled in the Institute are active in the frontier of theoretical physics, and form a strong research team in Physics Department.
    The past ten years are the decade of expansion and development for Physics Department.

Present state

    Physics Department now has a teaching and administrative staff of more than 140, among whom are 3 academicians of Chinese Academy of Sciences (2 of them are adjunct professors),
5 Guangbiao distinguished professors, 2 distinguished professors, about 40 professors, 40 associate professors, 9 senior engineers and senior laboratory technicians.
    The Physics Department consists of four research institutions, Zhejiang Institute of Modern Physics, Institute for Condensed Matter Physics, Institute of Optics and Institute of Applied Physics, and two teaching Institutions like College Physics Teaching Section and Experimental Physics Center. Authorized by the State Education Commission, 9 second-level subjects for Master degree, 8 for doctors and postdoctoral research are established. Theoretical physics and condensed matter physics, the 2 second-level subjects, are the key laboratories of Zhejiang Province.
    In the Physics Department, field theory and particle physics, condensed matter physics theory, computational physics and statistical physics, plasma physics, surface physics, low temperature physics, superconductors and superconductivity, optics in solids, nano-structure materials, soft condensed matter physics, atom and molecular physics, laser physics, quantum optics, atomic spectra, and the cross disciplines of science like bio- and medical physics, are the main research directions, and the research is among the lead in China, some fields are even advanced in the world. More than 250 articles are published every year, especially 2 and 17 articles have been in Nature and Physics Review Letter respectively in the past years. The total of publications in authoritative international journals is among the top in China. The fund for natural science has been rising steadily, and surpassed 4.5 million yuan last year. Many research projects have received national or provincial awards.
    The Physics Department now has altogether 550 students, including 120 Master degree candidates and 50 doctorial students. The undergraduate study lasts four years.
    The students in Zhejiang University pursue a good academic style and are very active in thoughts. A complete range of subjects and a detailed arrangement of courses in Zhejiang University, allow students great freedom to choose the lectures and to make them comprehensive and specialized talents. In addition, the regular scientific seminars, colloquia and other academic activities provide the students with the latest progress of the subject. Especially, Zhejiang University has a systematic training plan for undergraduates’ scientific research, such as SRTP and the Challenge Cup, which plays a decisive role in the combination of teaching and scientific research, and stimulates the students’ creativity. A variety of scholarships are founded for various majors and subjects. Those excellent students may receive special financial aids and awards. As for the graduates, besides the basic scholarship for every student, an abundance of research assistant positions, fellowships founded by schools, foundations and all circles in society are available.
   The tutorial system is adopted to foster the students’ ability both theoretically and experimentally in higher grades, hunting the talents who can further their study in physics or new branches of science as well as cross disciplines of sciences, or those who can work for scientific research and teaching, technology and management. The employment rate of the undergraduates in Physics Department reaches nearly 100% in their graduating year. Among them, the proportion of entering the graduate school is on the increase every year, and reaches 40% this year. Either those who become graduates or those who work in companies all show their outstanding flexibility and their great potential for development in cross disciplines. The students from the Physics Department of Zhejiang University are greatly welcome by the society.
    The duration for studying for the Master degree and the Doctorial degree is 2.5 and 3 years respectively, and for the Master and Doctor degrees together 5 years. The cultivation of the postgraduates is closely associated to the scientific research of the superadvisors. Currently, most of the professors in Physics Department are aged about 40, and have the research experience of at least one or two years abroad and are well-informed with the recent development of modern physics. Compared with other universities in China, the abundant directions of theoretical physics are another feature of the Physics Department in Zhejiang University.
    In 2001, authorized by the State Education Commission, Prof. You-quan Li and Prof. Bo Zheng, coming back from Germany, were invited as distinguished professors. It strengthens the research of theoretical physics and computational physics, and greatly facilitates national and international academic cooperation and exchanges. Profs. Li and Zheng set up and organize the colloquia recently. The colloquia introduce the latest advancement of the subject and activate the academic atmosphere. The colloquia are appreciated highly by teachers and students.
    Prof. Xiao-wei Tang, an academician of Chinese Academy of Science, moved in Physics Department in 2000. Based on his experience of scientific research of many years, he founded a research center for cross disciplines of science. His research promotes the cross-field research of physics, nonlinear science, biology and medicine, and gains him much reputation among the students. The adjunct Prof. Yu-zhu Wang, an academician, has established the lab of quantum optics, tackling the hot topics like supercooling atomic physics and Bose-Einstein condensation.
    In 1998, the academician Xian-tu He, a well-known theoretical physicist, an atomic scientist, took the chair of the School of Science and the director of Zhejiang Institute of Modern Physics. As the head of the physics subject in Zhejiang University, he apperceives the modern trends of physics, guides the research directions and explores the research area unceasingly. As the leader of the School of Science, he is fair and square with everyone. He reforms the management system steadily and puts efficient mechanism into effect for talents to grow up. As a senior scientist, he cares the young physicists without reservation, spares no effort to enroll both domestic and foreign outstanding young researchers to bring up a new generation of academic leaders. Prof. Xian-tu He has been exerting his utmost effort for Physics Department.

 A brief summary

    East China has been the cultural center over the past more than 1000 years, abounding with gifted scholars as well as famous poets and writers. It is undoubtedly the nice environment for study and scientific research. Physics in Zhejiang University is bound to hold a very promising future.



III. Professors in Physics Department


l        You-quan Li was born in 1963, received his Ph.D. degree in Department of Physics, Lanzhou University in 1989. Li was employed by Zhejiang University as a faculty member in Zhejiang Institute of Modern Physics in 1993, and was promoted to the full professor position in 1996. He was awarded the Alexander von Humboldt fellowship in 1998. In the past years, Prof. Li has ever worked as a guest professor in University of Cincinnati, Chinese University of Hong Kong, ETH-Lausanne and Augsburg University. After productive research on symmetries of quantum field theory and front topics in mathematical physics, he has been involved in theoretical condensed matter physics in recent years.
    A recent representative work of Prof. Li is on the orbital degrees of freedom of 3d electrons. Li together with Ma, Shi and Zhang indicated that the isotropic Hamiltonian expected to describe a variety of transitional metal oxides which has an enhanced symmetry from SU(2)×SU(2) to SU(4) [Li , Ma , Shi and Zhang, Phys. Rev. Lett. 81(1998) 3527; Li , Phys. Rev. Lett. 87(2001) 7208]. At this SU(4)-symmetric point, the quantum fluctuations of both the spin and orbital are enhanced and the “SU(4) singlet” is more stable in comparison to the conventional “spin SU(2) singlet.” Therefore, the orbital degrees of freedom help the realization of the resonating valence bond spin liquid, which has been looked for with great interest but has not yet been found in quantum magnets without orbital degeneracy (e.g., La2CuO4). As the basic unit of the SU(4) singlet is the plaquette, Li et. al. conjectured it might be realized in LiNiO2, and it was confirmed in experiment later on.
    Li’s work on spin systems with orbital degeneracy was granted the first prize by China Education Ministry, and a fund for distinguished young researchers by National Natural Science Foundation.
    In 2001, Prof. Li was honored as a distinguished professor by the Cheung Kong project of China Education Ministry. Now he has been establishing and leading a research team for theoretical studies on strongly correlated system and mesoscopic physics. Currently, the research interest includes non-perturbation approach to spin systems and strongly correlated systems, quantum phase transition, as well as spin involved transport in mesoscopic systems.


l        Bo Zheng was born in 1961, received his Ph.D. degree in Department of Physics, Zhongshan University in 1988. After the scientific visits in ICTP, Graz University and Free University in 1990, Zheng worked as a research associate and a senior research associate in Siegen University and Martin-Luther Halle University till 2001.10. Dr. Zheng was honored as a distinguished professor in Zhejiang Institute of Modern Physics by the Cheung Kong project of China Education Ministry in 2001.
Since 1994, Dr. Zheng has been engaged in the numerical study of nonequilibrium dynamic systems. Especially, Zheng together with his cooperators has systematically investigated the universal dynamic scaling behavior of critical dynamics far from equilibrium
[Zheng, Int.J.Mod.Phys.B12(1998)1419, review article]. Based on the short-time dynamic scaling form, a new method for numerical measurements of both static and dynamic critical exponents has been developed [Li, Schülke and Zheng, Phys.Rev.Lett.74(1995)3396; Zheng, Schulz and Trimper, Phys.Rev.Lett.82(1999) 1891]. The method does not suffer from critical slowing down. Compared with the non-local cluster algorithms, it can be applied to study local dynamics. The total SCI citation of the publications on this work reaches about 600 to date.

        Zheng’s work on numerical simulations of critical dynamics far from equilibrium was granted a fund for distinguished young researchers by National Natural Science Foundation.
    Prof. Zheng is now constructing and leading a research group in computational physics, statistical physics and soft condensed matter physics. Current research interest includes dynamic systems far from equilibrium, financial dynamics and other complex systems in bio- and medical physics. 

l        Ming-xing Luo was born in 1963, received his Ph.D. degree in Department of Physics, University of  Pennsylvania in 1990. After the postdoctoral research in Washington University from 1991 to 1993, Luo was employed by Zhejiang University as a faculty member in Zhejiang Institute of Modern Physics in 1994, and was promoted to the full professor position in 1997.
    Luo has been working in particle physics since his study for the doctoral degree. In a classical paper [Langacker and Luo, Phys.Rev.D44(1991)817], Luo and Langacker determined the , and b
y analyzing all existing experiments, and observed that the gauge coupling constants unify within the minimal supersymmetric standard model. It can be interpreted as an indirect support for both supersymmetry and grand unification theories. The SCI citation of this paper reaches nearly 600 now. In another seminal paper [Langacker, Luo and Mann, Rev.Mod. Phys.64(1992)87.], Luo and collaborators provided a theoretical framework for the high precision electroweak experiments, by introducing a systematic prescription for the analysis of experiments and the means of delineating the nature of new physics beyond the Standard Model. Recently, Luo and Xiao re-calculated the two-loop renormalization group equations in the standard model [hep-ph/0207271] and modified the long standing expressions of beta-functions.
    Prof. Luo is leading the research direction of particle physics and field theory in Physics Department. Current interest are applications of quantum field theories, precision tests of the standard model, supersymmetry and grand unification theories; phenomenologies of gravitation and string theories. 

l        Zhu-an Xu was born in 1966, received his Ph.D. degree in Department of Physics, Zhejiang University in 1994. From 1997.8 to 2000.2, Xu was working as a guest scientist in Princeton University. Xu was promoted to the full professor position in the Institute for Condensed Matter Physics in 2000.
    Prof. Xu has been active in experimental study of high-Tc superconductors in the last years. Unlike the low-Tc superconductors, the fluctuation superconductivity above Tc may extend to very high temperatures in the cuprate. In a recent article [Xu et al., Nature 406(2000)486], the Nernst effect and vortex-like excitations in high-Tc cuprates were investigated in an experiment with La2-xSrxCuO4. Xu et al. found a surprising enhanced Nernst signal in pseudogap regime (T>Tc). This indicates that vortices may exist at temperatures as high as 150 K in a series of crystals in which Tc ranges from below 4 K to 35 K. A possible scenario is that the condensate forms above 150 K in these materials. Why is the observed Tc strongly suppressed to 30 K? Because the condensate wavefunction is complex, the phase angle fluctuates strongly in space and time. This destroys the Meissner signal while leaving the condensate magnitude undiminished.  
    Xu has been granted a fund for distinguished young researchers by National Natural Science Foundation.

l        Xiao-wei Tang, an academician of Chinese Academy of Science, joined in the Physics Department in 2000.
  Prof. Tang is a nuclear physicist and high energy physicist. In the 70’s and 80’s, his research group joined the Mark-J collaboration at DESY in Hamburg, which discovered the gluon jet, and the L3 collaboration at CERN in Geneva, which determines the three generations of neutrino in nature. In 90’s, Tang was also in the Alpha Magnetic Spectrometer collaboration, which searches for anti-matter and dark matter in space. Then his research interest turned to the fields of life science and brain science. He pioneered the functional brain imaging studies in China and organized the neuroinformatics research in China. He was also the chief scientist of the National Research Project “Basic research in nuclear medicine and radiation therapy”. 

    Now Prof. Tang is leading a laboratory of cross disciplines and directing his energy to the bio-X, med-X and psycho-X studies.

l       Institute for Condensed Matter Physics consists of experimental and theoretical divisions. Besides the experimentalists Tang and Xu above, Profs. Shi-ning Bao, Gao-xiang Ye and Pi-mo He are leading strong groups on experimental study of solid, surface and interface. Prof. Ye has been active and creative on the experimental study of thin film growth on liquid surfaces since 1996 [Ye, Michely, Weidenhof et al., Phys.Rev.Lett. 81(1998)622]. In recent years, Prof. Bao and He et al. have had success on the growth and characteristics of C60 single crystal and related topics, such as K3C60 crystal in gas phase and growth of carbon nanotubes by chemical vapor deposition. Prof. He’s recent work on formation, electronic structures and interfaces in organic light-emitting diodes is also interesting and important [He, Au, Wang et al., Appl.Phys.Lett.76(2000)1422; He, Wang, Wong et al., Appl.Phys.Lett.79 (2001) 1561]. 

             Prof. Zheng-kuan Jiao has been fruitful in both experimental and theoretical study of high-Tc superconductors and superconductivity, and has published more than 300 scientific research papers. Dr. Qing-hu Chen is one of the youngest professors in the Physics Department, and productive in theoretical condensed matter physics. In a recent article [Chen, Tang and Tong, Phys.Rev.Lett.87(2001)067001], a long-standing dispute in current-voltage characteristic of KT systems is reconciled with extensive numerical simulations of superconducting Josephson junction arrays. 

           Prof. Pei-lin Cao is a reputated senior professor in the Department. An important work of Prof. Cao is on the Monte Carlo simulations of the microscopic processes of surface diffusion [Cao, Phys.Rev.Lett.73(1994)2595]. Cao proposed a transition type dependent method, obtained a new formula of calculating the Monte-Carlo time, and a relation between the surface diffusion coefficients and the surface order. The method has been applied to typical surfactant-mediated homoepitaxial systems. A new growth model, named the repulsive center network, is developed. This model is in good agreement with the experiments. 

l        Shao-min Wang is an expert in Matrix Optics, which is efficient in studying propagation and transformation of light. Prof. Wang and his cooperators specialize especially in the application: dam deformation measured by laser and by means of Fresnel lenses in vacuum line has been considered and established. It is a misaligned optical system and it is also a diffractive optical system. The ABCD matrix is thus augmented as a  matrix. Just at the time, novel phenomena of optical array were observed in the United States, which could be treated conveniently by means of a  matrix, and as a result, a new branch of optics is thus established [PROGRESS INOPTICS, 1988, Amsterdan]. On the other hand, new laser beams are discovered based on the concept of the nature of diffraction. The research projects “Array Optics”, “A CO2 Laser with New Beam” and “Dam Deformation Measured by Laser” have received the fourth prize of National Natural Science, the third prize of National Technical Invention and the second prize of National Scientific & Technical Progress Encouragements of China respectively. In 2000, a book named Matrix Optics by Wang and Zhao was formed and published by CHEP-Springer.


IV Research directions in Physics Department


l        Zhejiang Institute of Modern Physics


He, Xian-tu:    Nonlinear science, nonequilibrium statistical physics, nonlinear plasma physics, nuclear fusion science.

Chen, Yi-xin:   String theory, non-perturbative quantum field theory, quantum information and quantum computing.

Dai, Jian-Hui:  New physics in correlated electron systems, including quasi-1D organic conductors, quantum dots, heavy fermion alloys, 2D metals and high Tc cuprates.

Gao, Xiao-chun: Quantum field theory, systems with time-dependent Hamiltonians, integrable models and related topics.

Jin, Hong-ying:  Heavy flavor physics, exotic hadron physics, non-perturbative QCD.

Li, Kang:      Field theories, integrable systems, quantum group and field theory method in strong correlated system in condensed matter physics.

Li, You-quan:   Strongly correlated systems, quantum phase transition, mesoscopic physics

Lu, Ding-Hui:  Particle physics and nuclear physics, particularly in hadronic physics and nuclear matter under extreme conditions.

Luo, Ming-xin:  Quantum field theory and particle physics

Sheng, Zheng-mao:  Quantum field theory, string theory, integrable systems, condensed matter theory, nonlinear physics, molecular dynamics simulations.

Xu, Jing-bo:    Advanced topics in quantum theory, including time-dependent quantum systems, geometrical phase factor, field theory and algebraic methods in quantum optics, quantum computing and quantum information.

Ying, He-ping:  Lattice gauge theory, quantum phase transition and strongly correlated electron systems and cluster Monte Carlo simulations.

Zheng, Bo:     Computational physics, equilibrium and nonequilibrium statistical physics and related cross disciplines


l        Institute for Condensed Matter Physics


Tang, Xiao-wei:  High energy physics and nuclear physics, cross disciplines of physics, biology and medicine

Bao, Shi-ning Surface and interface physics, adsorbed layers on metal surfaces, materials physics of carbon clusters

Cao, Pei-lin:    Surface physics, cluster structure

Chen, Qing-hu:  Condensed Matter Physics, superconductivity, vortex dynamics

Fang, Ming-hu:  Superconductors, strongly correlated electron systems, transition metal oxides 

He, Pi-mo:     Surface, interface and thin film Physics, atomic and electronic structure on surface, growth and characters of low dimensional systems

Jiao, Zheng-kuan: High Tc superconductivity, low temperature physics, Colossal magneto-resistance, physics of nano-materials

Li, Hai-yang:   Surface and interface physics, synchrontron radiation

Sha, Jian:      Structure of nano-materials

Tan, Ming-qiu:  Density functional theory, strong correlated electron systems   

Tang, Jing-chang: Theory of surface structure and electrons, X-ray absorption spectra of solids

Xia, A-gen:     Polymer physics, thin film physics

Xu, Zhu-an:     High Tc superconductors, dynamics of charge-density-wave, CMR in perovskite manganites

Ye, Gao-xiang   Thin film physics, surface physics, nano-scale physics

Zhang, Lin-xi:   Polymer physics

Zhang, Xun-sheng: study of surface and interface structure with synchrotron radiation


l        Institute of Optics


Dai, Chang-jian:  Modern optical spectrumlaser physics and its applications, atomic


Lin, Qiang:     Laser physics, transformation of light, quantum optics

Liu, Zheng-dong: Quatum optics

Lu, Xuan-hui:   Transformation of light, solid-state laser, diffraction optics, laser technology and its application

Shen, Yong-hang: Optical fibre sensor, micro-solid-state laser, nonlinear optics

Wang, Shao-min: Matrix optics, nature of diffraction, subwavelength optics, properties of photons.

Wu, Hui-zhen   Optoelectronic materials and device, crystal film epitaxy, optical properties of solids  

Yao, Zhi-xin  Laser physics, metallic vapor laser


l        Institute of Applied Physics


Cao, Zhi-tong:   Chaos, neural network, wavelet analysis



Acknowledgement: Work supported in part by research funds of National Education Ministry. The author thanks deeply many helpful discussions with X.Y. Cai and Y.Q. Li .


B. Zheng 
Physics Department
Zhejiang University
Hangzhou 310027

P. R. China