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39篇 您的检索式:作者名="Pengxiang Xu"
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1Optically pumped terahertz sources显示文摘High-power terahertz(THz) generation in the frequency range of 0.1-10 THz has been a fast-developing research area ever since the beginning of the THz boom two decades ago, enabling new technological breakthroughs in spectroscopy, communication, imaging,etc. By using optical(laser) pumping methods with near-or mid-infrared(IR) lasers, flexible and practical THz sources covering the whole THz range can be realized to overcome the shortage of electronic THz sources and now they are playing important roles in THz science and technology. This paper overviews various optically pumped THz sources, including femtosecond laser based ultrafast broadband THz generation, monochromatic widely tunable THz generation, single-mode on-chip THz source from photomixing, and the traditional powerful THz gas lasers. Full descriptions from basic principles to the latest progress are presented and their advantages and disadvantages are discussed as well. It is expected that this review gives a comprehensive reference to researchers in this area and additionally helps newcomers to quickly gain understanding of optically pumped THz sources.ZHONG Kai SHI Wei XU DeGang LIU PengXiang WANG YuYe MEI JiaLin YAN Chao FU ShiJie YAO JianQuan 2017Science China(Technological Sciences)2017,60,12:9
2High-average-power, high-repetition-rate tunable terahertz difference frequency generation with GaSe crystal pumped by 2 μm dual-wavelength intracavity KTP optical parametric oscillator显示文摘We have demonstrated a high-average-power,high-repetition-rate optical terahertz(THz)source based on difference frequency generation(DFG)in the GaSe crystal by using a near-degenerate 2μm intracavity KTP optical parametric oscillator as the pump source.The power of the 2μm dual-wavelength laser was up to 12.33 W with continuous tuning ranges of 1988.0–2196.2 nm/2278.4–2065.6 nm for two waves.Different GaSe cystal lengths have been experimentally investigated for the DFG THz source in order to optimize the THz output power,which was in good agreement with the theoretical analysis.Based on an 8 mm long GaSe crystal,the THz wave was continuously tuned from 0.21 to 3 THz.The maximum THz average power of 1.66μW was obtained at repetition rate of 10 kHz under 1.48 THz.The single pulse energy amounted to 166 pJ and the conversion efficiency from 2 μm laser to THz output was 1.68×10^(-6).The signal-to-noise ratio of the detected THz voltage was 23 dB.The acceptance angle of DFG in the GaSe crystal was measured to be 0.16°.DEXIAN YAN YUYE WANG DEGANG XU PENGXIANG LIU CHAO YAN JIA SHI HONGXIANG LIU YIXIN HE LONGHUANG TANG JIANCHEN FENG JIANQIN GUO WEI SHI KAI ZHONG YUEN H.TSANG JIANQUAN YAO 2017Photonics Research2017,5,2:5
3Apple SERRATE negatively mediates drought resistance by regulating MdMYB88 and MdMYB124 and microRNA biogenesis显示文摘The function of serrate(SE)in miRNA biogenesis in Arabidopsis is well elucidated,whereas its role in plant drought resistance is largely unknown.In this study,we report that MdSE acts as a negative regulator of apple(Malus×domestica)drought resistance by regulating the expression levels of MdMYB88 and MdMYB124 and miRNAs,including mdm-miR156,mdm-miR166,mdm-miR172,mdm-miR319,and mdm-miR399.MdSE interacts with MdMYB88 and MdMYB124,two positive regulators of apple drought resistance.MdSE decreases the transcript and protein levels of MdMYB88 and MdMYB124,which directly regulate the expression of MdNCED3,a key enzyme in abscisic acid(ABA)biosynthesis.Furthermore,MdSE is enriched in the same region of the MdNECD3 promoter where MdMYB88/MdMYB124 binds.Consistently,MdSE RNAi transgenic plants are more sensitive to ABA-induced stomatal closure,whereas MdSE OE plants are less sensitive.In addition,under drought stress,MdSE is responsible for the biogenesis of mdm-miR399,a negative regulator of drought resistance,and negatively regulates miRNAs,including mdm-miR156,mdm-miR166,mdm-miR172,and mdm-miR319,which are positive regulators of drought resistance.Taken together,by revealing the negative role of MdSE,our results broaden our understanding of the apple drought response and provide a candidate gene for apple drought improvement through molecular breeding.Xuewei Li Pengxiang Chen Yinpeng Xie Yan Yan Liping Wang Huan Dang Jing Zhang Lingfei Xu Fengwang Ma Qingmei Guan 2020Horticulture Research2020,7,1:4
4N-phosphoryl amino acid models for P–N bonds in prebiotic chemical evolution显示文摘Post-translational modification of proteins by N-phosphorylation of the basic amino acid residues plays important roles in biological processes. The high-energy P–N bond might have contributed to the evolution of prebiotic chemistry. N-phosphoryl amino acids(PAAs) can serve as interesting small molecular models for the study of P–N bonds in prebiotic chemical evolution. PAAs are capable of simultaneously producing several important biomolecules such as polypeptides and oligonucleotides under mild reaction conditions. In this review, we describe the chemistry of PAAs, discusse their likely prebiotic origins and their reactivity and how they relate to biological P–N bond species. We also depict a possible prebiotic scenario mediated by PAAs in which PAAs may have acted as one of the essential forces driving prebiotic biomolecules to the first protocell.Feng Ni Chuan Fu Xiang Gao Yan Liu Pengxiang Xu Liu Liu Ye Lv Songsen Fu Ying Sun Daxiong Han Yan-Mei Li Yufen Zhao 2015Science China Chemistry2015,58,3:3
5Investigation and analysis of the linkage mechanism and whole process cost of livestock manure organic fertilizer显示文摘In recent years,the utilization of manure resources for livestock and poultry farming has attracted a widespread attention,and manure resources utilization models suitable for different regional characteristics have formed gradually.Among them,the production of organic fertilizer from animal manure is a vital utilization method.However,there are still some problems such as high production costs,difficult sales,and the unwillingness of farmers to use organic fertilizers which have affected the breeding cycle and the sustainability of manure treatment in livestock and poultry breeding.This article selected 371 organic fertilizer plants,related farms and farmers in China,focusing on the main links of the entire process of livestock manure-organic fertilizer-farm application,and studied the mode of animal manure collection by organic fertilizer plants.The costs of organic fertilizer production and farmland application were discussed.Moreover,suggestions were made for the promotion and implementation of large-scale organic fertilizers to make good utilization of manure resources in livestock and poultry farming.Shanshan Dong Bin Sui Yujun Shen Haibo Meng Lixin Zhao Jingtao Ding Haibin Zhou Xi Zhang Hongsheng Cheng Jian Wang Ran Li Liqiu Song Pengxiang Xu Ji Li 2020International Journal of Agricultural and Biological Engineering2020,13,2:2
6Seismogenic Structures of the 2006 ML4.0 Dangan Island Earthquake Offshore Hong Kong显示文摘The northern margin of the South China Sea, as a typical extensional continental margin, has relatively strong intraplate seismicity. Compared with the active zones of Nanao Island, Yangjiang, and Heyuan, seismicity in the Pearl River Estuary is relatively low. However, a ML4.0 earthquake in 2006 occurred near Dangan Island(DI) offshore Hong Kong, and this site was adjacent to the source of the historical M5.8 earthquake in 1874. To reveal the seismogenic mechanism of intraplate earthquakes in DI, we systematically analyzed the structural characteristics in the source area of the 2006 DI earthquake using integrated 24-channel seismic profiles, onshore–offshore wide-angle seismic tomography, and natural earthquake parameters. We ascertained the locations of NW-and NE-trending faults in the DI sea and found that the NE-trending DI fault mainly dipped southeast at a high angle and cut through the crust with an obvious low-velocity anomaly. The NW-trending fault dipped southwest with a similar high angle. The 2006 DI earthquake was adjacent to the intersection of the NE-and NW-trending faults, which suggested that the intersection of the two faults with different strikes could provide a favorable condition for the generation and triggering of intraplate earthquakes. Crustal velocity model showed that the high-velocity anomaly was imaged in the west of DI, but a distinct entity with low-velocity anomaly in the upper crust and high-velocity anomaly in the lower crust was found in the south of DI. Both the 1874 and 2006 DI earthquakes occurred along the edge of the distinct entity. Two vertical cross-sections nearly perpendicular to the strikes of the intersecting faults revealed good spatial correlations between the 2006 DI earthquake and the low to high speed transition in the distinct entity. This result indicated that the transitional zone might be a weakly structural body that can store strain energy and release it as a brittle failure, resulting in an earthquake-prone area.XIA Shaohong CAO Jinghe SUN Jinlong LV Jinshui XU Huilong ZHANG Xiang WAN Kuiyuan FAN Chaoyan ZHOU Pengxiang 2018Journal of Ocean University of China2018,17,1:2
7Vertex-distinguishing total colorings of graphs显示文摘ZHANG Zhongfu QIU Pengxiang XU Baogen 2008Ars Combinatoria2008,87,:1
8Vertex-distinguishing total coloring of graphs 显示文摘Zhang Zhongfu Qiu Pengxiang Xu Baogen 2008Ars Combinatoria2008,87,:1
9Vertexdistinguishing total coloring of graphs 显示文摘ZHANG Zhongfu QIU Pengxiang XU Baogen 2008Ars Combinatoria2008,87,:1
10vertex-distinguishing total colorings of graphs 显示文摘ZHANG Zhongfu QIU Pengxiang XU Baogen 2008Ars Combinatoria2008,87,:1
11verter - dis- tinguishing total colourings of graphs 显示文摘ZHANG zhongfu QIU Pengxiang XU Baogen 2008Ars Combinatoria2008,87,:1
12Vertex-distinguishing total colorings of graphs 显示文摘ZHANG Zhongfu QIU Pengxiang XU Baogen 2008Ars Combinatoria2008,87,:1
13Vertex-distinguishing total colorings of graphs 显示文摘ZHANG Zhongfu QIU Pengxiang XU Baogen 2008Ars Combinatoria2008,87,:1
14An invasive zone in human liver cancer identified by Stereo-seq promotes hepatocyte–tumor cell crosstalk,local immunosuppression and tumor progression显示文摘Dissecting and understanding the cancer ecosystem,especially that around the tumor margins,which have strong implications for tumor cell infiltration and invasion,are essential for exploring the mechanisms of tumor metastasis and developing effective new treatments.Using a novel tumor border scanning and digitization model enabled by nanoscale resolution-SpaTial Enhanced REsolution Omics-sequencing(Stereo-seq),we identified a 500µm-wide zone centered around the tumor border in patients with liver cancer,referred to as“the invasive zone”.We detected strong immunosuppression,metabolic reprogramming,and severely damaged hepatocytes in this zone.We also identified a subpopulation of damaged hepatocytes with increased expression of serum amyloid A1 and A2(referred to collectively as SAAs)located close to the border on the paratumor side.Overexpression of CXCL6 in adjacent malignant cells could induce activation of the JAK-STAT3 pathway in nearby hepatocytes,which subsequently caused SAAs’overexpression in these hepatocytes.Furthermore,overexpression and secretion of SAAs by hepatocytes in the invasive zone could lead to the recruitment of macrophages and M2 polarization,further promoting local immunosuppression,potentially resulting in tumor progression.Clinical association analysis in additional five independent cohorts of patients with primary and secondary liver cancer(n=423)showed that patients with overexpression of SAAs in the invasive zone had a worse prognosis.Further in vivo experiments using mouse liver tumor models in situ confirmed that the knockdown of genes encoding SAAs in hepatocytes decreased macrophage accumulation around the tumor border and delayed tumor growth.The identification and characterization of a novel invasive zone in human cancer patients not only add an important layer of understanding regarding the mechanisms of tumor invasion and metastasis,but may also pave the way for developing novel therapeutic strategies for advanced liver cancer and other solid tumors.Liang Wu Jiayan Yan Yinqi Bai Feiyu Chen Xuanxuan Zou Jiangshan Xu Ao Huang Liangzhen Hou Yu Zhong Zehua Jing Qichao Yu Xiaorui Zhou Zhifeng Jiang Chunqing Wang Mengnan Cheng Yuan Ji Yingyong Hou Rongkui Luo Qinqin Li Liang Wu Jianwen Cheng Pengxiang Wang Dezhen Guo Waidong Huang Junjie Lei Shang Liu Yizhen Yan Yiling Chen Sha Liao Yuxiang Li Haixiang Sun Na Yao Xiangyu Zhang Shiyu Zhang Xi Chen Yang Yu Yao Li Fengming Liu Zheng Wang Shaolai Zhou Huanming Yang Shuang Yang Xun Xu Longqi Liu Qiang Gao Zhaoyou Tang Xiangdong Wang Jian Wang Jia Fan Shiping Liu Xinrong Yang Ao Chen Jian Zhou 2023Cell Research2023,33,8:1
15Spatial Variations of b-Values in the Coastal Area of Guangdong显示文摘We used earthquake catalogs recorded by Guangdong Seismological Network from 2008 to 2014 to resolve the spatial variations of b-values in the coastal area of Guangdong, particularly in three key research areas(Yangjiang, Heyuan, and offshore Nanao Island) with strong seismicity. Our results revealed that b-values exhibited significant spatial variations, and zones with low b-values could indicate the most likely seismogenic area of large earthquakes. We observed three clear low b-value patches in the offshore Nanao Island. We found a distinct high b-value peak at the depth of 11 km and two minimum peaks at about 14 and 7–8 km in the Yangjiang area. The overall b-values generally decrease with depth in the Heyuan area. The spatial variations of b-values reflect tectonic anomalies; that is, the ‘low-high-low' distribution of b-values in the offshore Nanao Island and the Yangjiang area may indicate the anomaly of the crustal structure with a weak layer. The b-values of reservoir-induced seismicity are obviously lower than that induced by tectonism. This finding indicates that the reservoir area is generally at high stress state under the condition of high pore pressure. We inferred that large earthquakes might be prone to occur at 10–12 km depth in the offshore Nanao Island, at 12–15 km depth in the Yangjiang area, and at the lower part of the seismic activity zone in the Heyuan area. Moreover, the upstream area of the Xinfengjiang reservoir is the most likely area of future large earthquakes in the Heyuan area.ZHOU Pengxiang XIA Shaohong SUN Jinlong CAO Jinghe XU Huilong ZHAO Fang CHEN Chuanxu 2018Journal of Ocean University of China2018,17,1:1
16Vertex distinguishing total coloring of graphs显示文摘Zhang Zhongfu Qiu Pengxiang Xu Baogen 2008Ars Combina- toria2008,87,:1
17Vertex Distinguishing Total Coloring of Graphs显示文摘Zhang Zhongfu Qiu Pengxiang Xu Baoen 2008Ars Combinatoria2008,87,:1
18Widely tunable and monochromatic terahertz difference frequency generation with organic crystal DSTMS显示文摘Pengxiang Liu Degang Xu Yin Li Xinyuan Zhang Yuye Wang Jianquan Yao Yicheng Wu 2014EPL (Europhysics Letters)2014,,6:1
19Ver- tex- diainguishing total coloring of graphs 显示文摘Zhang Zhongfu Qiu Pengxiang Xu Baogen 2008Ars Comb2008,87,:1
20Vertex-distinguishing total coloring of graphs显示文摘Zhang Zhongfu Qiu Pengxiang Xu Baogen etal 2008Ars Combinatoria2008,87,:1
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