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Selenium-induced Changes in Activities of Antioxidant Enzymes and Content of Photosynthetic Pigments in Spirulina platensis

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Journal of Integrative Plant Biology 2008年第1期50卷 40-48页

作者： tian-feng chen Wen-Jie Zheng Yum-Shing Wong Fang Yang Department of Biology The Chinese University of Hong Kong Hong Kong SAR China Department of Chemistry Jinan University Guangzhou 510632 China

Spirulina platensis exposed to various selenium （Se） concentrations （0, 10, 20, 40, 80, 150, 175, 200, 250 mg/L） accumulated high amounts of Se in a dose- and time-dependent manner. Under low Se concentrations （〈150 mg/L）, Se induced increases in biomass concentration, content of photosynthetic pigments, and activities of glutathione peroxidase （GPX）, superoxide dismutase （SOD）, catalase （CAT） and Gua-dep peroxidases （POD）, which indicates that antioxidant enzymes play an important role in protecting cells from Se stress. Higher Se concentrations （≥175 mg/L） led to higher Se accumulation and increases in activities of GPX, SOD, CAT and POD, but also induced lipid peroxidation （LPO） coupled with potassium leakage and decreases in biomass concentration and contents of photosynthetic pigment. The results indicate that increases in activities of the antioxidant enzymes were not sufficient to protect cell membranes against Se stress. Time-dependent variations in the activities of antioxidant enzymes, contents of chlorophyll a and carotenoid and the LPO level were also investigated under representative Se concentrations of 40 and 200mg/L. Opposite variation trends between SOD-CAT activities, and GPX-POD-APX activities were observed during the growth cycles. The results showed that the prevention of damage to cell membranes of S. platensis cells could be achieved by cooperative effects of SOD-CAT and GPX-POD-APX enzymes. This study concludes that S. platensis possessed tolerance to Se and could protect itself from phytotoxicity induced by Se by altering various metabolic processes.

关键词： accumulation antioxidant enzymes photosynthetic pigments selenium Spirulina platensis.

Short-time maritime target detection based on polarization scattering characteristics

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Journal of Systems Engineering and Electronics 2024年第1期35卷 55-64页

作者： chen Shichao LUO feng tian Min LYU Wanghan College of Computer and Information Engineering(College of Artificial Intelligence) Nanjing Tech UniversityNanjing 211816China Hangzhou Institute of Technology Xidian UniversityHangzhou 311200China

In this paper,a detection method combining Cameron decomposition based on polarization scattering characteristics in sea clutter background is ***,the Cameron decomposition is exploited to fuse the radar echoes of full polarization channels at the data *** to the artificial material structure on the surface of the target,it can be shown that the non-reciprocity of the target cell is stronger than that of the clutter ***,based on the analysis of the decomposition results,a new feature with scattering geometry characteristics in polarization domain,denoted as Cameron polarization decomposition scattering weight(CPD-SW),is extracted as the test statistic,which can achieve more detailed descriptions of the clutter scattering characteristics utilizing the difference between their scattering ***,the superiority of the proposed CPD-SW detector over traditional detectors in improving detection performance is verified by the IPIX measured dataset,which has strong stability under short-time observation in threshold detection and can also improve the separability of feature space zin anomaly detection.

关键词： sea clutter small target radar detection Cameron decomposition characteristics analysis

Intracoronary adenosine improves myocardial perfusion in late reperfused myocardial infarction

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Chinese Medical Journal 2008年第3期121卷 195-199页

作者： tian feng chen Yun-dai LUE Shu-zheng SONG Xian-tao YUAN Fei FANG Fang LI Zhi-an Department of Cardiology Beijing Anzhen Hospital of CapitalUniversity Medical Science Beijing 100029 China

Background Myocardial perfusion associates with clinical syndromes and prognosis. Adenosine could improve myocardial perfusion of acute myocardial infarction within 6 hours, but few data are available on late perfusion of myocardial infarction （MI）. This study aimed at quantitatively evaluating the value of intracoronary adenosine improving myocardial perfusion in late reperfused MI with myocardial contrast echocardiography （MCE）. Methods Twenty-six patients with anterior wall infarcts were divided randomly into 2 groups： adenosine group （n=12） and normal saline group （n=-14）. Their history of myocardial infarction was about 3-12 weeks. Adenosine or normal saline was given when the guiding wire crossed the lesion through percutaneous coronary intervention （PCI）, then the balloon was dilated and stent （Cypher/Cypher select） was implanted at the lesion. Contrast pulse sequencing MCE with Sonovue contrast via the coronary route was done before PCI and 30 minutes after PCI. Video densitometry and contrast filled-blank area were calculated with the CUSQ off-line software. Heart function and cardiac events were followed up within 30 days. Results Perfusion in the segments of the criminal occlusive coronary artery in the adenosine group was better than that in the saline group （5.71：L-0.29 VS 4.95±1.22, P〈0.05）. Ischemic myocardial segment was deminished significantly after PCI, but the meliorated area was bigger in the adenosine group than in the saline group （（1.56±0.60） cm^2 vs （1.02±0.56） cm^2, P〈0.05）. The video densitometry in cntical segments was also improved significantly in the adenosine group （5.53±0.36 VS 5.26±0.35, P〈0.05）. Left ventricular ejection fraction （LVEF） was improved in all patients after PCI, but EF was not significant between the two groups （（67±6）% vs （62±7）%, P〉0.05）. There was no in-hospital or 30-day major adverse cardiac event （MACE） in the adenosine group but 3 MACE in the saline group in 30 days after PCI. Conclusions Adenosine could

关键词： adenosine myocardial contrast echocardiography myocardial reperfusion myocardial infarction

Automatic SOC Equalization Strategy of Energy Storage Units with DC Microgrid Bus Voltage Support

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Energy Engineering 2024年第2期121卷 439-459页

作者： Jingjing tian Shenglin Mo feng Zhao Xiaoqiang chen School of Automation&Electrical Engineering Lanzhou Jiaotong UniversityLanzhou730070China Key Laboratory of Opto-Technology and Intelligent Control(Lanzhou Jiaotong University) Ministry of EducationLanzhou730070China

In this paper,an improved sag control strategy based on automatic SOC equalization is proposed to solve the problems of slow SOC equalization and excessive bus voltage fluctuation amplitude and offset caused by load and PV power variations in a stand-alone DC *** strategy includes primary and secondary *** them,the primary control suppresses the DC microgrid voltage fluctuation through the I and II section control,and the secondary control aims to correct the P-U curve of the energy storage system and the PV system,thus reducing the steady-state bus voltage *** simulation results demonstrate that the proposed control strategy effectively achieves SOC balancing and enhances the immunity of bus *** proposed strategy improves the voltage fluctuation suppression ability by approximately 39.4%and 43.1%under the PV power and load power fluctuation conditions,***,the steady-state deviation of the bus voltage,△U_(dc) is only 0.01–0.1 V,ensuring stable operation of the DC microgrid in fluctuating power environments.

关键词： Automatic equalization independent DC microgrid improve droop control secondary control state of charge

Frequency Domain Fatigue Evaluation on SCR Girth-Weld Based on Structural Stress

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China Ocean Engineering 2024年第2期38卷 255-270页

作者： ZHANG Long ZHAO tian-feng College of Safety and Ocean Engineering China University of Petroleum(Beijing)Beijing 102249China

The Steel Catenary Riser(SCR)is a vital component for transporting oil and gas from the seabed to the floating *** harsh environmental conditions and complex platform motion make the SCR’s girth-weld prone to fatigue *** structural stress fatigue theory and Master S-N curve method provide accurate predictions for the fatigue damage on the welded joints,which demonstrate significant potential and compatibility in multi-axial and random fatigue ***,we propose a new frequency fatigue model subjected to welded joints of SCR under multiaxial stress,which fully integrates the mesh-insensitive structural stress and frequency domain random process and transforms the conventional welding fatigue technique of SCR into a spectrum analysis technique utilizing structural ***,a full-scale FE model of SCR with welds is established to obtain the modal structural stress of the girth weld and the frequency response function(FRF)of modal coordinate,and a biaxial fatigue evaluation about the girth weld of the SCR can be achieved by taking the effects of multi-load correlation and pipe-soil interaction into *** research results indicate that the frequency-domain fatigue results are aligned with the time-domain results,meeting the fatigue evaluation requirements of the SCR.

关键词： SCR girth weld random vibration self(cross)power spectrum structural stress method biaxial fatigue damage

Evaluation of neointimal coverage in patients with coronary artery aneurysm formation after drug-eluting stent implantation by optical coherence tomography

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Chinese Medical Journal 2013年第11期126卷 2092-2097页

作者： tian feng chen Yun-dai chen Lian SUN Zhi-jun GUO Jun JIN Qin-hua LIU Chang-N WANG Jin-da LIU Hong-bin Department of Cardiology Chinese People's Liberation ArmyGeneral Hospital Beijing 100853 China

Background The vessel healing in patients with coronary artery aneurysms （CAA） that form after drug-eluting stent （DES） implantation is not clear. This study aims to assess the vessel healing in patients with CAA formation after DES implanation. Methods From June 2008 to August 2011, follow-up coronary angiography was conducted on 1160 patients who underwent percutaneous coronary intervention （PCI）. The average period of follow-up was about （18.95±13.05） months. A total of 175 patients who underwent DES implantation into de novo lesions and who underwent coronary angiography and optical coherence tomography （OCT） examination during follow-up were identified. Patients were divided into the CAA group （n=31） and non-CAA group （n=144） based on the results of the coronary angiography. The cardiac events including angina and acute myocardial infarction were noted; in addition, the neointimal thickness and the frequency of strut malapposition and strut uncoverage were also noted. Results A greater proportion of incomplete neointimal coverage （17.17% vs. 1.90%, P 〈0.001） and strut malapposition （18.20% vs. 1.38%, P 〈0.001） were observed in the CAA group. The neointimal thickness in the CAA group was significantly thinner than that in the non-CAA group （（146.6±94.8） μm vs. （192.5＋97.1）μm, P 〈0.001）, as detected via OCT. Patients with CAA formation had a higher frequency of cardiac events including angina pectoris （25.81% vs. 6.25%, P=0.001） and acute myocardial infarction （9.68% vs. 0.13%, P=0.002） and thrombosis （16.13% vs. 0.69%, P 〈0.001）. The longitudinal length of the CAA in the cardiac event group was significantly longer than in the no cardiac event group （（20.0±9.07） mm vs. （12.05±5.38） ram, P=0.005）. Conclusion CAA formation after DES implantation is frequently associated with cardiac events as a result of stent malapposition and incomplete neointimal coverage.

关键词： optical coherence tomography coronary artery aneurysms drug-eluting stent neointimal coverage

Iterative Signal Detection Based Soft Interference Cancellation for Satellite-Terrestrial Downlink NOMA Systems

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China Communications 2024年第8期21卷 249-263页

作者： Sun Meng Zhang Qi Yao Haipeng Gao Ran Xin Xiangjun tian feng feng Weiying chen Dong School of Electronic Engineering Beijing University of Posts and Telecommunications(BUPT)Beijing 100876China Beijing Key Laboratory of Space-Ground Interconnection and Convergence State Key Laboratory of Information Photonics and Optical CommunicationsSchool of Electronic EngineeringBeijing University of Posts and Telecommunications(BUPT)Beijing 100876China School of Information and Communication Engineering Beijing University of Posts and Telecommunications(BUPT)Beijing 100876China Beijing Institute of Technology Beijing 100081China Beihang University Beijing 100191China China Academy of Space Technology(CAST) Beijing 100094China

To improve the bit error rate(BER)performance of multi-user signal detection in satelliteterrestrial downlink non-orthogonal multiple access(NOMA)systems,an iterative signal detection algorithm based on soft interference cancellation with optimal power allocation is *** that power allocation has a significant impact on BER performance,the optimal power allocation is obtained by minimizing the average BER of NOMA *** to the allocated powers,successive interference cancellation(SIC)between NOMA users is performed in descending power *** each user,an iterative soft interference cancellation is performed,and soft symbol probabilities are calculated for soft *** improve detection accuracy and without increasing the complexity,the aforementioned algorithm is optimized by adding minimum mean square error(MMSE)signal estimation before detection,and in each iteration soft symbol probabilities are utilized for soft-decision of the current user and also for the update of soft interference of the previous *** results illustrate that the optimized algorithm ***-IDBSIC significantly outperforms joint multi-user detection and SIC detection by 7.57dB and 8.03dB in terms of BER performance.

关键词： non-orthogonal multiple access(NOMA) resource allocation satellite-terrestrial communication signal detection soft interference cancellation

Coronary plaque response after drug eluting stent implantation assessed by serial optical coherence tomography analysis

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Chinese Medical Journal 2011年第22期124卷 3752-3756页

作者： tian feng chen Yun-dai chen Lian SUN Zhi-jun LIU Chang-fu GUO Jun JIN Qin-hua WANG Jin-da GAI Lu-yue Department of Cardiology Chinese People＇s Liberation Army General Hospital Beijing 100853 China

Background In general, percutaneous coronary intervention （PCI） relieves vessel stenosis by implantation of a stent, however, the relationship between plaque characteristics and response after stenting is not clear. Methods We enrolled 68 patients （68 vessels） with diagnosed unstable angina pectoris that prospectively underwent PCI and an optical coherence tomography （OCT） examination was done before and after stenting. Coronary plaques were classified as fibrous, lipid-rich and calcified plaque according to OCT examination, and fibrous cap thickness, lumen eccentricity, stent expansion, stent malapposition, tissue prolapse, thrombosis, dissection and stent symmetry were noted. Results The frequency of prolapse was higher in lipid-rich plaques than fibrous plaques （85% vs. 40%, P 〈0.001）. Dissection most often occurred in fibrous plaque compared with lipid-rich and calcified plaques （60% vs. 32% vs. 29%, P 〈0.001）. The frequency of stent strut malapposition in calcified plaques was higher than firous and lipid-rich plaques （71% vs. 40% vs. 5%, P 〈0.001）. In-stent micro-thrombosis was detected only in lipid-rich plaques, with a frequency of 37% （15/41）. The risk factors of micro-thrombosis after PCI were cap thickness （OR 0.903, 95% CI 0.829-0.985）, lumen eccentricity （OR 1.147, 95% CI 1.012-1.30）, and stent length （OR 1.495, 95% CI 1.032-2.166）. Conclusion Plaque response after PCI is associated with its characteristics, and of those, micro-thrombosis after stenting in lipid-rich plaques was the most significant finding and can be predicted.

关键词： coronary heart disease, optical coherence tomography plaque, stent

Tunable topological polaritons by dispersion tailoring of an active metasurface

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Advanced Photonics 2024年第4期6卷 59-69页

作者： Shaojie Wang Ke chen Shufang Dong tian Jiang Junming Zhao Yijun feng Nanjing University School of Electronic Science and Engineering

Hyperbolic polaritons are known to exist in materials with extreme anisotropy, exhibiting exotic optical properties that enable a plethora of unusual phenomena in the fields of polaritonics and ***, achieving simultaneous low-dimensionality, high-speed controllability, and on-demand reconfigurability of the polaritons remains unexplored despite their excellent potential in light–matter interactions, photonic integrated circuits, and optoelectronic devices. Here, we propose a metasurface approach to integrating artificially engineered electromagnetic anisotropy with fast-controllable electronic elements, offering a new route to realize active topological polaritons. Experiments showcase the proposed reconfigurable metasurface can support real-time transitions of designer polaritons from elliptical to flat, and then to hyperbolic and circular isofrequency contours. Correspondingly, the in-plane surface wavefront undergoes the transitions from convex to collimating, concave, and eventually back to convex. By exploiting the topological variations in polariton dispersions, we observe intriguing phenomena of controllable field canalization and tunable planar focusing. Furthermore, we report the concept of a planar reconfigurable integrated polariton circuit by spatially tailoring the distributions of polariton isofrequency contours, unveiling rich dispersion engineering possibilities and active control capabilities. We may provide an inspiring platform for developing planar active plasmonic devices with potential applications in subdiffraction-resolution imaging,sensing, and information processing.

关键词： active tuning anisotropic polaritons dispersion engineering hyperbolic metasurface topological transitions