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| 1 | Commissioning progress of the FAST显示文摘The Five-hundred-meter Aperture Spherical radio Telescope(FAST) was completed with its main structure installed on September 25, 2016, after which it entered the commissioning phase. This paper aims to introduce the commissioning progress of the FAST over the past two years. To improve its operational reliability and ensure effective observation time, FAST has been equipped with a real-time information system for the active reflector system and hierarchical commissioning scheme for the feed support system, which ultimately achieves safe operation of the two systems. For meeting the high-performance indices, a highprecision measurement system was set up based on the effective control methods that were implemented for the active reflector system and feed support system. Since the commissioning of the FAST, a low-frequency ultra-wideband receiver and 19-beam1.05-1.45 GHz receiver have been mainly used. Telescope efficiency, pointing accuracy, and system noise temperature were completely tested and ultimately achieved the acceptance indices of the telescope. The FAST has been in the process of national acceptance preparations and has begun to search for pulsars. In the future, it will still strive to improve its capabilities and expand its application prospects. | Peng Jiang YouLing Yue HengQian Gan Rui Yao Hui Li GaoFeng Pan JingHai Sun DongJun Yu HongFei Liu NingYu Tang Lei Qian JiGuang Lu Jun Yan Bo Peng ShuXin Zhang QiMing Wang Qi Li Di Li | 2019 | Science China(Physics,Mechanics & Astronomy)2019，62，5： | 11 |
| 2 | Concurrent catalytic removal of typical volatile organic compound mixtures over Au-Pd/α-MnO2 nanotubes显示文摘α-MnO_2 nanotubes and their supported Au-Pd alloy nanocatalysts were prepared using hydrothermal and polyvinyl alcohol-protected reduction methods, respectively. Their catalytic activity for the oxidation of toluene/m-xylene, acetone/ethyl acetate, acetone/m-xylene and ethyl acetate/m-xylene mixtures was evaluated. It was found that the interaction between Au-Pd alloy nanoparticles and α-MnO_2 nanotubes significantly improved the reactivity of lattice oxygen, and the 0.91 wt.% Au0.48 Pd/α-MnO_2 nanotube catalyst outperformed the α-MnO_2 nanotube catalyst in the oxidation of toluene, m-xylene, ethyl acetate and acetone. Over the0.91 wt.% Au0.48 Pd/α-MnO_2 nanotube catalyst,(i) toluene oxidation was greatly inhibited in the toluene/m-xylene mixture, while m-xylene oxidation was not influenced;(ii) acetone and ethyl acetate oxidation suffered a minor impact in the acetone/ethyl acetate mixture; and(iii) m-xylene oxidation was enhanced whereas the oxidation of the oxygenated VOCs(volatile organic compounds) was suppressed in the acetone/m-xylene or ethyl acetate/m-xylene mixtures. The competitive adsorption of these typical VOCs on the catalyst surface induced an inhibitive effect on their oxidation, and increasing the temperature favored the oxidation of the VOCs. The mixed VOCs could be completely oxidized into CO_2 and H_2 O below 320°C at a space velocity of 40,000 m L/(g·hr). The 0.91 wt.% Au0.48 Pd/α-MnO_2 nanotube catalyst exhibited high catalytic stability as well as good tolerance to water vapor and CO_2 in the oxidation of the VOC mixtures. Thus, the α-MnO_2 nanotube-supported noble metal alloy catalysts hold promise for the efficient elimination of VOC mixtures. | Yunsheng Xia Lu Xia Yuxi Liu Tao Yang Jiguang Deng Hongxing Dai | 2018 | Journal of Environmental Sciences2018，30，2： | 7 |
| 3 | Long-term variations of X-ray pulse profiles for the Crab pulsar:data analysis and modeling显示文摘The pulse profiles of the Crab pulsar(as well as some other pulsars)vary with time.They can lead to a major source of intrinsic timing noise,which lacks a detailed physical model.The phase separation?between the first left peak(P1)and the second right peak(P2)is a key parameter that shows the variations of pulse profiles for the Crab pulsar.It was found that the evolution of?has a tendency with increasing rates of 0.82?±0.25?,0.80?±0.54?,and 0.77?±0.28?per century for the 2-6,6-15,and15-60 ke V bands,respectively.Furthermore,the flux ratios(P2/P1)of X-ray pulse profiles in the three bands were calculated,and the derived flux ratios were consistent with the radio and X-ray measurements of the Insight-HXMT.In addition to discovering the physical origin of the pulse changes,the high-SNR X-ray pulse profiles were simulated in the annular gap model,and two model parameters(e.g.,the maximum emission heights of the two peaks)were observed to slightly affect the variations of peak separation.We fitted the long-term variations of emission heights of the two peaks and discovered that the emission heights showed increasing tendencies with time.Variations of these emission heights induced a characteristic period derivative,and a complete formula for both the magnetic dipole radiation and wind-particle-induced variations of the moment of inertia was used for the pulsar’s spin-down to obtain the variation rate˙αof the magnetic inclination angle,which was-1.60?per century.Intrinsic timing noise is observed to be mainly induced by the variations of pulse profiles,which might correlate with a characteristic spin period derivative arising from the fluctuations of the emission regions.This work will lay a foundation for understanding the origin of intrinsic timing noise and making high-precision timing models in the future. | LunHua Shang YuanJie Du XiangQun Cui ShiJun Dang JiGuang Lu JunTao Bai QiJun Zhi YouLi Tuo LinLi Yan LiangWei Huang XinYuan Zhang XiaoMin Bei QingQing Lin GuoJun Qiao Hua Shen RiHong Zhu | 2020 | Science China(Physics,Mechanics & Astronomy)2020，63，10： | 2 |
| 4 | A wet adhesion inspired biomimetic pad with direction dependence and adaptability显示文摘A novel adhesive pad for a climbing robot, inspired by a stick insect's smooth pad, is proposed. The micro structure pattern and inclined fiber of a stick insect's pad are mimicked, and an adhesion force is produced based on its wet adhesion mechanism. Firstly, the wet adhesion model is discussed and the pad is designed; secondly, the adhesion characteristics, adhesion direction dependence and adaptability are analyzed; finally, the proposed pad is fabricated using a thermoplastic elastomer, which is a hydrophilic and viscoelastic material. Experimental results show that the adhesion performance of the pad is good, and normal adhesion and friction can reach to 0.65 N and 3 N. Furthermore, the adhesion of the pad is direction dependent and self-adaptive. | LI MingHe HE Bin QIN HaiYan ZHOU YanMin LU HanXiong YUE JiGuang | 2011 | Chinese Science Bulletin2011，56，18： | 2 |
| 5 | Causal propagation of signals in strangeon matter显示文摘The state equation for strangeon matter is very stiff due to the non-relativistic nature of its particles and their repulsive interaction,such that pulsar masses as high as~3 M_⊙ would be expected. However, an adiabatic sound speed, c_s=(?P/?ρ)~(1/2), is usually superluminal in strangeon matter, and the dynamic response of a strangeon star(e.g., binary merger) is not tractable in numerical simulations. In this study, we examined signal propagation in strangeon matter and calculate the actual propagation speed, c_(signal).We found that the causality condition, c_(signal)< c, is satisfied and the signal speed is presented as a function of stellar radius. | JiGuang Lu EnPing Zhou XiaoYu Lai RenXin Xu | 2018 | Science China(Physics,Mechanics & Astronomy)2018，61，8： | 1 |
| 6 | A novel electrochemical method to evaluate the cytotoxicity of heavy metals显示文摘 | Xiaolin Zhu Hongwei Qin JiGuang Liu Zeshi Zhang Ying Lu Xing Yuan Dongmei Wu | 2014 | Journal of Hazardous Materials2014，，： | 1 |
| 7 | Repeating fast radio bursts: Coherent circular polarization by bunches显示文摘Fast radio bursts(FRBs) are millisecond-duration signals that are highly dispersed at distant galaxies. However, the physical origin of FRBs is still unknown. Coherent curvature emission by bunches, e.g., powered by starquakes, has already been proposed for repeating FRBs. It has the nature of understanding narrowband radiation exhibiting time-frequency drifting. Recently, a highly active FRB source, i.e., FRB 20201124A, was reported to enter a newly active episode and emit at least some highly circular-polarized bursts. In this study, we revisit the polarized FRB emission, particularly investigating the production mechanisms of a highly circular polarization(CP) by deriving the intrinsic mechanism and propagative effect. The intrinsic mechanisms of invoking charged bunches are approached with radiative coherence. Consequently, a highly CP could naturally be explained by the coherent summation of outcome waves, generated or scattered by bunches, with different phases and electric vectors. Different kinds of evolutionary trajectories are found on the Poincaré sphere for the bunch-coherent polarization, and this behavior could be tested through future observations. Cyclotron resonance can result in the absorption of R-mode photons at a low altitude region of the magnetosphere, and an FRB should then be emitted from a high-altitude region if the waves have strong linear polarization. Circularly polarized components could be produced from Faraday conversion exhibiting a λ-oscillation, but the average CP fraction depends only on the income wave, indicating a possibility of a highly circular-polarized income wave. The analysis could be welcome if extremely high(e.g., almost 100%) CP from repeating FRBs is detected in the future. Finally, the production of a bulk of energetic bunches in the pulsar-like magnetosphere is discussed, which is relevant to the nature of the FRB central engine. | Wei-Yang Wang Jin-Chen Jiang Jiguang Lu Heng Xu Jiangwei Xu Kejia Lee Jifeng Liu Renxin Xu | 2022 | Science China(Physics,Mechanics & Astronomy)2022，65，8： | 0 |
| 8 | Was Wuhan the early epicenter of the COVID-19 pandemic?——a critique显示文摘Recently, Worobey et al.(2022) published a report entitled ‘The Huanan Seafood Wholesale Market in Wuhan was the early epicenter of the COVID-19 pandemic' that succinctly summarizes their study [1]. A pre-print version of this study had earlier elicited a series of highprofile media coverages [2,3]. All these reports deliver a social-political message that the Huanan market is the epicenter of COVID-19. | Yanan Cao Lingling Chen Hua Chen Yupeng Cun Xiaofeng Dai Hongli Du Feng Gao Fengbiao Guo Yalong Guo Pei Hao Shunmin He Shunping He XiongLei He Zheng Hu Boon-Peng Hoh Xin Jin Qian Jiang Qinghua Jiang Asifullah Khan Hong-Zhi Kong Jinchen Li Shuai Cheng Li Ying Li Qiang Lin Jianquan Liu Qi Liu Jian Lu Xuemei Lu Shujin Luo Qinghua Nie Zilong Qiu Tieliu Shi Xiaofeng Song Jianzhong Su Sheng-ce Tao Chaolong Wang Chuan-Chao Wang Guo-Dong Wang Jiguang Wang Qi Wu Shaoyuan Wu Shuhua Xu Yu Xue Wenjun Yang Zhaohui Yang Kai Ye Yuan-Nong Ye Li Yu Fangqing Zhao Yiqiang Zhao Weiwei Zhai Dandan Zhang Liye Zhang Houfeng Zheng Qi Zhou Tianqi Zhu Ya-ping Zhang | 2023 | National Science Review2023，10，4： | 0 |
| 9 | Periodic interstellar scintillation variations of PSRs J0613-0200 and J0636+5128 associated with the Local Bubble shell显示文摘Annual variations of interstellar scintillation can be modelled to constrain parameters of the ionized interstellar medium.If a pulsar is in a binary system,then investigating the orbital parameters is possible through analysis of the orbital variation of scintillation.In observations carried out from 2011 to 2020 by the European Pulsar Timing Array radio telescopes,PSRs J0613-0200and J0636+5128 show strong annual variations in their scintillation velocity,while the former additionally exhibits an orbital fluctuation.Bayesian theory and Markov-chain-Monte-Carlo methods are used to interpret these periodic variations.We assume a thin and anisotropic scattering screen model,and discuss the mildly and extremely anisotropic scattering cases.PSR J0613-0200is best described by mildly anisotropic scattering,while PSR J0636+5128 exhibits extremely anisotropic scattering.We measure the distance,velocity,and degree of anisotropy of the scattering screen for our two pulsars,finding that scattering screen distances from Earth for PSRs J0613-0200 and J0636+5128 are 316_(-20)^(+28)pc and 262_(-38)^(+96)pc,respectively.The positions of these scattering screens are coincident with the shell of the Local Bubble towards both pulsars.These associations add to the growing evidence of the Local Bubble shell as a dominant region of scattering along many sightlines. | Yulan Liu Robert A.Main Joris P.W.Verbiest Ziwei Wu Krishnakumar M.Ambalappat Jiguang Lu David J.Champion Ismael Cognard Lucas Guillemot Kuo Liu James W.Mc Kee Nataliya Porayko Golam.M.Shaifullah Gilles Theureau | 2023 | Science China(Physics,Mechanics & Astronomy)2023，66，11： | 0 |
| 10 | Estimation of Solar Observations with the Five-hundred-meter Aperture Spherical Radio Telescope(FAST)显示文摘We present the estimation of solar observation with the Five-hundred-meter Aperture Spherical radio Telescope(FAST).For both the quiet Sun and the Sun with radio bursts,when pointing directly to the Sun,the total power received by FAST would be out of the safe operational range of the signal chain,even resulting in damage to the receiver.As a conclusion,the Sun should be kept at least~2°away from the main beam during observations at~1.25 GHz.The separation for lower frequency should be larger.For simplicity,the angular separation between the FAST beam and the Sun is suggested to be~5°for observations at 200 MHz or higher bands. | Lei Qian Zhichen Pan Hongfei Liu Hengqian Gan Jinglong Yu Lei Zhao Jiguang Lu Cun Sun Jingye Yan Peng Jiang | 2023 | Research in Astronomy and Astrophysics2023，23，1： | 0 |
| 11 | Pulsar giant pulse: Coherent instability near light cylinder显示文摘Giant pulses(GPs) are extremely bright individual pulses of radio pulsar. In microbursts of Crab pulsar, which is an active GP emitter, zebra-pattern-like spectral structures are observed, which are reminiscent of the 'zebra bands' that are observed in type Ⅳ solar radio flares. However, band spacing linearly increases with the band center frequency of ~5-30 GHz. In this study, we propose that the Crab pulsar GP can originate from the coherent instability of plasma near a light cylinder. Further, the growth of coherent instability can be attributed to the resonance observed between the cyclotron-resonant-excited wave and the background plasma oscillation. The particles can be injected into the closed-field line regions owing to magnetic reconnection near a light cylinder. These particles introduce a large amount of free energy that further causes cyclotron-resonant instability, which grows and amplifies radiative waves at frequencies close to the electron cyclotron harmonics that exhibit zebra-pattern-like spectral band structures. Further, these structures can be modulated by the resonance between the cyclotron-resonant-excited wave and the background plasma oscillation. In this scenario, the band structures of the Crab pulsar can be well fitted by a coherent instability model, where the plasma density of a light cylinder should be ~10^(13-15) cm^(-3), with an estimated gradient of >5.5 × 10~5 cm^(-4). This process may be accompanied by high-energy emissions. Similar phenomena are expected to be detected in other types of GP sources that have magnetic fields of ? 106 G in a light cylinder. | WeiYang Wang JiGuang Lu SongBo Zhang XueLei Chen Rui Luo RenXin Xu | 2019 | Science China(Physics,Mechanics & Astronomy)2019，62，7： | 0 |
| 12 | Advancing pulsar science with the FAST显示文摘As the rump left behind after an extremely gravity-induced supernova of an evolved massive star,a pulsar is made of cool CBM(i.e.,compressed baryonic matter at a low temperature).Pulsars are not only testbeds for fundamental interactions(e.g.,the nature of gravity[1]and of the strong force at low energies[2]),but also essential tools for detecting nanoHz gravitational waves[3].The pulsar science,whatever,usually depends on the measurement of pulsar radiation,e.g.,pulsar monitoring and timing.Additionally,searching new pulsars for further investigation is also an important focus of this research field.Pulsars have a very good showing,and have never stopped presenting surprises since the first discovery in 1967,because of the continuing development of advanced facilities. | JiGuang Lu KeJia Lee RenXin Xu | 2020 | Science China(Physics,Mechanics & Astronomy)2020，63，2： | 0 |
| 13 | FAST:The Five-Hundred-Meter Aperture Spherical Radio Telescope显示文摘In the 90 years since its inception,radio astronomy has become the setting of almost all major astronomical discoveries and a hothouse for Nobel Prizes in Physics.As a result,countries all over the world have actively explored new engineering concepts to build large-aperture radio telescopes.Limited by their self-weight and wind load,100 m radio telescopes are regarded as the maximum limit of traditional radio telescopes.This perspective allowed the Arecibo 305 m telescope—built by Cornell University in the United States in 1963—to dominate the field for more than half a century.During this period,scholars have been exploring how to further expand their horizons in order to make a breakthrough in the problem of the universe. | Peng Jiang Hengqian Gan Rui Yao Jinghai Sun Jiguang Lu Dongjun Yu Hui Li Jinglong Yu Bin Dong Xiaoming Chai Jianing Yin | 2023 | Engineering2023，，9： | 0 |
| 14 | Study of three rotating radio transients with FAST显示文摘Rotating radio transients(RRATs) are peculiar astronomical objects whose emission mechanism remains under investigation.In this paper, we present observations of three RRATs, J1538+2345, J1854+0306 and J1913+1330, carried out with the Fivehundred-meter Aperture Spherical radio Telescope(FAST). Specifically, we analyze the mean pulse profiles and temporal flux density evolutions of the RRATs. Owing to the high sensitivity of FAST, the derived burst rates of the three RRATs are higher than those in previous reports. RRAT J1854+0306 exhibited a time-dynamic mean pulse profile, whereas RRAT J1913+1330 showed distinct radiation and nulling segments on its pulse intensity trains. The mean pulse profile variation with frequency is also studied for RRAT J1538+2345 and RRAT J1913+1330, and the profiles at different frequencies could be well fitted with a cone-core model and a conal-beam model, respectively. | JiGuang Lu Bo Peng Kuo Liu Peng Jiang YouLing Yue Meng Yu Ye-Zhao Yu FeiFei Kou Lin Wang FAST Collaboration | 2019 | Science China(Physics,Mechanics & Astronomy)2019，62，5： | 0 |
| 15 | FAST ultra-wideband observation of abnormal emission-shift events of PSR B0919+06显示文摘PSR B0919+06 is known for its abnormal emission phenomenon, where the pulse emission window occasionally shifts progressively in longitude and returns afterwards. The physical mechanism behind this phenomenon is still under investigation. In this paper, we present our ultra-wideband observation of this pulsar using the Five-hundred-meter Aperture Spherical radio Telescope(FAST), with simultaneous measurements in the frequency ranges 280-780 and 1250-1550 MHz. We have identified three abnormal events, each of which becomes less apparent as the frequency decreases. At 1400 MHz, the averaged profile slightly shifted after the first and third abnormal events, implying a relationship between abnormal event and profile variation. We also found a linear trend in the left-edge position of the averaged profiles between the first and third events as well as after the third event, suggesting the existence of a slow-drifting mode between the two major events. The second event has a comparatively small shift in phase and is thus categorized as a 'small flare state'. During the third event, a sequence of approximately nine pulses was seen to significantly weaken in all frequency bands, likely associated with the pseudo-nulling observed at 150 MHz.A three-component de-composition analysis of the normal averaged profiles shows that the trailing component is dominant at our observing frequencies, while the centre component has a comparatively steeper spectrum. We found the overall flux density in an abnormal event to slightly differ from that in an ordinary state, and the difference shows a frequency dependence. A comparison of the normal, abnormal and dimmed averaged profile indicates that the leading component is likely to be stable in all states. | Ye-Zhao Yu Bo Peng Kuo Liu ChengMin Zhang Lin Wang FeiFei Kou JiGuang Lu Meng Yu FAST Collaboration | 2019 | Science China(Physics,Mechanics & Astronomy)2019，62，5： | 0 |
| 16 | The radiation structure of PSR B2016+28 observed with FAST显示文摘With the largest dish Five-hundred-meter Aperture Spherical radio Telescope(FAST), both the mean and single pulses of PSR B2016+28, especially including the single-pulse structure, are investigated in detail in this study. The mean pulse profiles at different frequencies can be well fitted in a conal model, and the peak separation of intensity-dependent pulse profiles increases with intensity. The integrated pulses are obviously frequency dependent(pulse width decreases by ~20% as frequency increases from 300 to 750 MHz), but the structure of single pulses changes slightly(the corresponding correlation scale decreases by only~1%). This disparity between mean and single pulses provides independent evidence for the existence of the RS-type vacuum inner gap, indicating a strong bond between particles on the pulsar surface. Diffused drifting sub-pulses are analyzed. The results show that the modulation period along pulse series(P_3) is positively correlated to the separation between two adjacent sub-pulses(P_2). This correlation may hint a rough surface on the pulsar, eventually resulting in the irregular drift of sparks. All the observational results may have significant implications in the dynamics of pulsar magnetosphere and are discussed extensively in this paper. | JiGuang Lu Bo Peng RenXin Xu Meng Yu Shi Dai WeiWei Zhu Ye-Zhao Yu Peng Jiang YouLing Yue Lin Wang FAST Collaboration | 2019 | Science China(Physics,Mechanics & Astronomy)2019，62，5： | 0 |
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