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Radiation efficiency and energy distribution from a borehole dipole source in the vertical transverse isotropic formation

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Petroleum Science 2024年第6期21卷 4034-4051页

作者： Xi-Hao Gu Fan-Tong Kong Yuan-Da Su xiao-ming tang School of Geosciences China University of Petroleum(East China) Centre for Exploration Geophysics Curtin University Ocean College Jiangsu University of Science and Technology Laoshan Laboratory

Dipole Shear-Wave Reflection Survey(DSRS) has gained wide application in identifying unconventional reservoirs in anisotropic formations. Previous investigations have illuminated how boreholes complicate the distribution of acoustic energy. However, these models have not accounted for the anisotropic context, rendering them insufficient for analyzing acoustic energy distribution and radiation efficiency in anisotropic formations. We derive expressions for energy flux and radiation efficiency from a borehole dipole source in the vertical-transverse isotropic(VTI) media using the Umov-Poynting vector and steepest-descent solution. Utilizing this approach, we systematically evaluate the sensitivity of anisotropic parameters to energy flux and radiation efficiency, unveiling intricate variations of these properties across frequency and anisotropic parameters. Our findings emphasize the substantial influence of formation anisotropy on energy distribution from a dipole source inside the borehole. Due to energy conversion between wave modes, five radiation wave modes are elicited by the dipole source, with the SH wave retaining its status as the prime candidate for DSRS in fast formations owing to its elevated radiation efficiency. Conversely, the qP-qP wave exhibits advantages over S waves in unconsolidated formations. A key distinction between isotropic and anisotropic media is the presence of dominant excitation frequencies in the low-frequency domain. The significance of dominant excitation-frequency bands is validated by field data, emphasizing their pivotal role. These results offer valuable insights for designing DSRS measurement strategies, which have broad application expectations for unconventional oil and gas exploration.

关键词： Dipole source Shear-wave reflection survey Anisotropic formation Energy flux Radiation efficiency

Preparation of the Phosphors BaAl_2O_4:Eu, RE (RE=Dy, Ho) by Microwave Heating Technique and Observation of Long Phosphorescence

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Chinese Chemical Letters 1999年第8期10卷 709-712页

作者： Ying Liang LIU xiao ming tang Xi De CHEN Bing Fu LEI De Xiong FENG (Department of Chcmistry. Jinan University. Guangzhou 510632) Jinan Univ Dept Chem Guangzhou 510632 Peoples R China

The phosphors BaAl2O4: Eu2+. RE (RE=Dy. Ho) have been prepared by the microwave heating technique. The long-lasting phosphorescence in the phosphors of the barium aluminate activated with europium and other rare ear... 详细信息

关键词： Barium aluminate microwave heating technique europium(Ⅱ) Phosphorescence

P-and SV-wave dispersion and attenuation in saturated microcracked porous rock with aligned penny-shaped fractures

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Petroleum Science 2024年第1期21卷 143-161页

作者： Sheng-Qing Li Wen-Hao Wang Yuan-Da Su Jun-Xin Guo xiao-ming tang School of Geosciences China University of Petroleum(East China)Qingdao 266580ShandongChina Laoshan National Laboratory Qingdao 266071ShangdongChina Guangdong Provincial Key Laboratory of Geophysical High-resolution Imaging Technology Southern University of Science and TechnologyShenzhen 518055GuangdongChina Department of Earth and Space Sciences Southern University of Science and TechnologyShenzhen 518055GuangdongChina

P-and SV-wave dispersion and attenuation have been extensively investigated in saturated poroelastic media with aligned ***,there are few existing models that incorporate the multiple wave attenuation mechanisms from the microscopic scale to the macroscopic ***,in this work,we developed a unified model to incorporate the wave attenuation mechanisms at different scales,which includes the microscopic squirt flow between the microcracks and pores,the mesoscopic wave-induced fluid flow between fractures and background(FB-WIFF),and the macroscopic Biot's global flow and elastic scattering(ES)from the *** tang's modified Biot's theory and the mixed-boundary conditions,we derived the exact frequency-dependent solutions of the scattering problem for a single penny-shaped fracture with oblique incident P-and *** then developed theoretical models for a set of aligned fractures and randomly oriented fractures using the Foldy *** results indicated that microcrack squirt flow considerably influences the dispersion and attenuation of P-and SV-wave *** coupling effects of microcrack squirt flow with the FB-WIFF and ES of fractures cause much higher velocity dispersion and attenuation for P waves than for SV *** oriented fractures substantially reduce the attenuation caused by the FB-WIFF and ES,particularly for the ES attenuation of SV *** a comparison with existing models in the limiting cases and previous experimental measurements,we validated our model.

关键词： Aligned fractures P-and SV-wave Dispersion and attenuation Microcracked porous background FB-WIFF Elastic scattering Squirt flow

Activation of peroxymonosulfate by sustainable biomass-based carbon nanotubes for controlling the spread of plant viruses in water environments

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Journal of Environmental Sciences 2025年第3期149卷 99-112页

作者： Jian tang Yujie Wang JunMa Yujie Chen ming Chen College of Resources and Environment Yangtze UniversityWuhan 430100China Key Laboratory of Reservoir Aquatic Environment Chongqing Institute of Green and Intelligent TechnologyChinese Academy of SciencesChongqing 400714China Chongqing School University of Chinese Academy of SciencesChongqing 400714China School of Geography and Tourism Chongqing Normal UniversityChongqing 400714China

With the increasing demand for water in hydroponic systems and agricultural irrigation,viral diseases have seriously affected the yield and quality of *** removing plant viruses in water environments,virus transmission can be prevented and agricultural production and ecosystems can be *** so far,there have been few reports on the removal of plant viruses in water ***,in this study,easily recyclable biomass-based carbon nanotubes catalysts were synthesized with varying metal activities to activate peroxymonosulfate(PMS).Among them,the magnetic 0.125Fe@NCNTs-1/PMS system showed the best overall removal performance against pepper mild mottle virus,with a 5.9 log_(10)removal within 1 ***,the key reactive species in the 0.125Fe@NCNTs-1/PMS system is^(1)O_(2),which can maintain good removal effect in real water matrices(river water and tap water).Through RNA fragment analyses and label free analysis,it was found that this system could effectively cleave virus particles,destroy viral proteins and expose their *** capsid protein of pepper mild mottle virus was effectively decomposed where serine may be the main attacking sites by^(1)O_(2).Long viral RNA fragments(3349 and 1642 nt)were cut into smaller fragments(∼160 nt)and caused their *** summary,this study contributes to controlling the spread of plant viruses in real water environment,which will potentially help protect agricultural production and food safety,and improve the health and sustainability of ecosystems.

关键词： Pepper mild mottle virus Removal Plant virus spread Biomass-based carbon nanotubes Water environments

Low-profile,low sidelobe array antenna with ultrawide beam coverage for UAV communication

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Chinese Journal of Aeronautics 2025年第1期38卷 444-454页

作者： Mei LI Zhiliang SHANG Lin PU ming-Chun tang Lei ZHU School of Microelectronics and Communication Engineering Chongqing UniversityChongqing 400044China Department of Electrical and Computer Engineering University of MacaoMacao SAR 999078China

This paper presents a design method to implement an antenna array characterized by ultra-wide beam coverage,low profile,and low Sidelobe Level(SLL)for the application of Unmanned Aerial Vehicle(UAV)air-to-ground *** array consists of ten broadside-radiating,ultrawide-beamwidth elements that are cascaded by a central-symmetry series-fed network with tapered currents following Dolph-Chebyshev distribution to provide low ***,an innovative design of end-fire Huygens source antenna that is compatible with metal ground is presented.A low-profile,half-mode Microstrip Patch Antenna(MPA)is utilized to serve as the magnetic dipole and a monopole is utilized to serves as the electric dipole,constructing the compact,end-fire,grounded Huygens source ***,two opposite-oriented end-fire Huygens source antennas are seamlessly integrated into a single antenna element in the form of monopole-loaded MPA to accomplish the ultrawide,broadside-radiating *** consideration has been applied into the design of series-fed network as well as antenna element to compensate the adverse coupling effects between elements on the radiation *** indicates an ultrawide Half-Power Beamwidth(HPBW)of 161°and a low SLL of-25 dB with a high gain of 12 d Bi under a single-layer *** concurrent ultrawide beamwidth and low SLL make it particularly attractive for applications of UAV air-to-ground communication.

关键词： Array antenna Broad beam Fan beam Low sidelobe level Chebyshev synthesis UAV communication

Effects of bamboo invasion on forest structures and diameter-height allometries

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FOREST ECOSYSTEMS 2025年第1期12卷 38-45页

作者： Ouyang, ming Eziz, Anwar xiao, Shuli Fang, Wenjing Cai, Qiong Ma, Suhui Zhu, Jiangling Yang, Qingpei Hu, Jinming tang, Zhiyao Fang, Jingyun Yunnan Univ Sch Ecol & Environm Sci Kunming Peoples R China Yunnan Univ Key Lab Transboundary Ecosecur Southwest Minist Educ Kunming Peoples R China Peking Univ Inst Ecol Coll Urban & Environm Sci Beijing Peoples R China Peking Univ Key Lab Earth Surface Proc Minist Educ Beijing Peoples R China Chinese Acad Sci Xinjiang Inst Ecol & Geog State Key Lab Desert & Oasis Ecol Key Lab Ecol Safety & Sustainable Dev Arid Lands Urumqi Peoples R China Jiangxi Agr Univ Jiangxi Prov Key Lab Bamboo Germplasm Resources & Nanchang Peoples R China Jiangxi Agr Univ Coll Forestry Nanchang Peoples R China

Forest structure is fundamental in determining ecosystem function, yet the impact of bamboo invasion on these structural characteristics remains unclear. We investigated 219 invasion transects at 41 sites across the distribution areas of Moso bamboo (Phyllostachys edulis) in China to explore the effects of bamboo invasion on forest structural attributes and diameter-height allometries by comparing paired plots of bamboo, mixed bamboo-tree, and non-bamboo forests along the transects. We found that bamboo invasion decreased the mean and maximum diameter at breast height, maximum height, and total basal area, but increased the mean height, stem density, and scaling exponent for stands. Bamboo also had a higher scaling exponent than tree, particularly in mixed forests, suggesting a greater allocation of biomass to height growth. As invasion intensity increased, bamboo allometry became more plastic and decreased significantly, whereas tree allometry was indirectly promoted by increasing stem density. Additionally, a humid climate may favour the scaling exponents for both bamboo and tree, with only minor contributions from topsoil moisture and nitrogen content. The inherent superiority of diameter-height allometry allows bamboo to outcompete tree and contributes to its invasive success. Our findings provide a theoretical basis for understanding the causes and consequences of bamboo invasion.

关键词： Moso bamboo Forest structure Stand density DBH-Height allometry Scaling exponent Wetness index

Deciphering fungal metabolon coupling tandem inverse-electrondemand Diels-Alder reaction and semipinacol rearrangement for the biosynthesis of spiro polycyclic alkaloids

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Science China Chemistry 2025年第1期68卷 288-296页

作者： Shuai Liu Wen-Qiang Xu Ying-Tong Di Man-Cheng tang Ding-Kang Chen ming-ming Cao Yao-Wen Chang Hong-Yu tang Chun-Mao Yuan Jun-Bo Yang Zhi-Li Zuo Han Guo Zi-Fei Xu Ying Zeng Yun-Dong Wu xiao-Jiang Hao Key Laboratory of Phytochemistry and Natural Medicines(Chinese Academy of Sciences) Kunming Institute of BotanyChinese Academy of SciencesKunming 650201China Lab of Computational Chemistry and Drug Design State Key Laboratory of Chemical OncogenomicsPeking University Shenzhen Graduate SchoolShenzhen 518055China Shenzhen Bay Laboratory Shenzhen 518055China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Microbial Metabolism School of Life Sciences&BiotechnologyShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Functions and Applications of Medicinal Plants Guizhou Medical UniversityGuiyang 550014China Molecular Biology Experimental Center Germplasm Bank of Wild Species in Southwest ChinaKunming Institute of BotanyChinese Academy of SciencesKunming 650201China Yunnan Key Laboratory for Wild Plant Resources Kunming Institute of BotanyChinese Academy of SciencesKunming 650201China Research Unit of Chemical Biology of Natural Anti-Virus Products Chinese Academy of Medical SciencesBeijing 100730China

In the intricate process of natural product biosynthesis,a metabolon can enhance metabolic flux by associating sequential enzymes.A fungal metabolon,comprising of flavin-dependent monooxygenase Spe F and P450 monooxygenase Spe G,is identified in the biosynthesis of spiro polycyclic alkaloids(+)-notoamide B and its diastereomer(+)-versicolamide *** notoamide E as a substance,Spe F/Spe G metabolon can control the stereoselectivity of its 2,3-epoxidation,followed by hydrogen atom ion at C-17 to generate reactive epoxide tau-m A with dienyl iminium ***,(+)-notoamide B and(+)-versicolamide B are produced via tandem nonenzymatic inverse-electron-demand Diels-Alder reaction and semipinacol *** provides the first example of metabolon in the biosynthesis of spiro-prenylated indole alkaloids.

关键词： metabolon Diels-Alder reaction semipinacol rearrangement biosynthesis notoamides spiro polycyclic alkaloids

A quantum-chemical study on the Mannich reaction with polynitromethanes

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Acta Chimica Sinica English Edition 1989年第4期7卷 289-294页

作者： xiao He-ming tang Ze-Hua East China Institute of Technology Nanjing East China Institute of Technology Nanjing

According to the results of SCF-CNDO/2 computation, we propose employing the'ladder weighting summation' to define a G_e index which is used to measure the relative magnitudeof the nucleophilicity of the relevant amine and pseudo acid components in a Mannich reaction. Wealso put forward an A_e index to measure the relative magnitude of the electrophilicity of methylene-amine cationic species in the same reaction. A combined use of both G_e and A_e indices is suggestedto evaluate the feasibility of a Mannich reaction for the polynitromethanes and the stability of theproducts. These results are consistent with those conclusions drawn from 'soft-hard acid-basetheory'.

关键词： A quantum-chemical study on the Mannich reaction with polynitromethanes CNDO

Highly efficient catalytic transfer hydrogenation for the conversion of nitrobenzene to aniline over PdO/TiO_(2):The key role of in situ switching from PdO to Pd

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Journal of Environmental Sciences 2025年第2期148卷 515-528页

作者： Anqi Lu xiaokang Xiang ming Lei Shuangshuang Huang Bingbing Liang Siyu Zhao Lihua Zhu Heqing tang College of Resources and Environmental Science South-Central Minzu UniversityWuhan 430074China School of Chemistry and Chemical Engineering Huazhong University of Science and TechnologyWuhan 430074China School of Physics and Technology Center for Electron MicroscopyMOE Key Laboratory of Artificial Micro-and Nano-Structuresand Institute for Advance StudiesWuhan UniversityWuhan 430072China

The reduction of nitrobenzene to aniline is very important for both pollution control and chemical ***,difficulties still remain in developing a catalytic system having high efficiency and selectivity for the production of ***,it was found that PdO nanoparticles highly dispersed on TiO_(2)support(PdO/TiO_(2))functioned as a highly efficient catalyst for the reduction of nitrobenzene in the presence of *** favorable conditions,95%of the added nitrobenzene(1 mmol/L)was reduced within 1 min with an ultra-low apparent activation energy of 10.8 kJ/mol by using 0.5%PdO/TiO_(2)as catalysts and 2 mmol/L of NaBH4 as reductants,and the selectivity to aniline even reached up to 98%.The active hydrogen specieswere perceived as dominant species during the hydrogenation of nitrobenzene by the results of isotope labeling experiments and ESR spectroscopic.A mechanismwas proposed as follows:PdO activates the nitro groups and leads to in-situ generation of Pd,and the generated Pd acts as the reduction sites to produce active hydrogen *** this catalytic system,nitrobenzene prefers to be adsorbed on the PdO nanoparticles of the PdO/TiO_(2)***,the addition of NaBH4 results in in-situ generation of a Pd/PdO/TiO_(2)composite from the PdO/TiO_(2)composite,and the Pd nanoclusters would activate NaBH4 to generate active hydrogen species to attack the adsorbed nitro *** work will open up a new approach for the catalytic transfer hydrogenation of nitrobenzene to aniline in green chemistry.

关键词： Catalytic transfer hydrogenation Reduction Pd Nitrobenzene Aniline