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Effect of Si/Si_(1-y)C_(y)/Si Barriers on the Characteristics of Sil-xGex/Si Resonant Tunneling Structures

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Chinese Physics Letters 2000年第11期17卷 844-846页

作者： HAN Ping cheng Xue-mei Department of Physics Nanjing UniversityNanjing 210093 Masao SakurabaYoung-Cheon JeongTakashi MatsuuraJunichi Murota Research Institute of Electrical CommunicationTohoku University 2-1-1 KatahiraAoba-kuSendai 980-8577Japan

P-type double barrier resonant tunneling diodes (RTD) with the single Si0.6Ge0.4 quantum well and double Si0.6Ge0.4spacer have been realized by using an ultra clean low-pressure chemical vapor deposition system. The effect of Si_(1-y)C_(y) layer on the characteristics of the devices was shown by comparing the current-voltage (I-V) characteristics of RTD’s of the barriers of Si layers with that of Si/ Si_(1-y)C_(y)/Si structures. The peak voltage was gradually increased and the resonant current decreased obviously with increasing C content in the Si/ Si_(1-y)C_(y)/Si barriers. The origin of the phenomena above can be attributed to the C related deep acceptor levels in the Si/ Si_(1-y)C_(y)/Si barriers. The possible mechanism for the observed I- V characteristics was shown more clearly by increasing C content to 3% and changing the thicknesses of Si and Si_(1-y)C_(y) layers in the Si/Si_(1-y)C_(y)/Si barriers.

关键词： Si/Si resonant Tunnel

Fluorescence Microscopic Image Analysis of Nucleic Acids Based on The Capillary Flow Directed Assembly Ring of Neutral Red-nucleic Acid Supramolecular Complexes

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Chemical Research in Chinese Universities 2003年第3期19卷 275-279页

作者： LI Yuan fang HUANG cheng zhi Laboratory of Supramolecular Chemistry and Biomedical Analysis College of Chemistry and Chemical EngineeringSouthwest Normal UniversityChongqing 400715P.R.China

It is critical to establish a direct and precise method with a high sensitivity and selectivity in analytical chemistry. In this research, making use of a well known phenomenon of capillary flow, we have proposed an image analysis method of nucleic acids at the price of a small amount of sample. When a droplet of the supramolecular complex solution, formed by neutral red and nucleic acids(NA) under an approximate neutral condition, was placed on the hydrophobic surface of dimethyl dichlorosilane pretreated glass slides, and it was evaporated, the supramolecular complex exhibited the periphery of the droplet due to the capillary effect, and accumulated there to form a red capillary flow directed assembly ring(CFDAR). A typical CFDAR has an outer diameter of (2 r ) about 1.18 mm and a ring width(2 δ ) of about 41 μm. Depending on the experimental conditions, a variety of CFDAR can be assembled. The experimental results are in agreement with our former theoretical discussion. It was found that when a droplet volume is 0.1 μL, the fluorescence intensity of the CFDAR formed by the NR NA is in proportion to the content of calf thymus DNA in the range of 0-0.28 ng, fish sperm DNA of 0-0.24 ng and yeast RNA of 0-0.16 ng with the limit of detection(3 σ ) of 1 7, 1.4 and 0.9 pg, respectively for the three nucleic acids.

关键词： Nuclei acids(NA) Neutral red(NR) Ring assembly Solid support surface Fluorescence imaging analysis

Host-Guest Chemistry and Nonlinear Optical Behaviors of Aluminum Molecular Rings

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Chinese Journal of Chemistry 2024年第21期42卷 2581-2588页

作者： Yi-Bo Chen cheng-Yang Zhang Dan Luo Ran-Qi Chen Jian Zhang Shu-mei Chen Wei-Hui fang College of Chemistry Fuzhou UniversityFuzhouFujian350108 China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002 China Fujian College University of Chinese Academy of SciencesNo.155 Yangqiao West RoadFuzhouFujian350002 China

Macrocyclic compounds are of great interest for their ability to capture guest molecules into their *** particular,host-guest interaction plays a crucial role in the formation of supramolecular ***,two host-guest supramolecular compounds,[Al_(8)(OH)_(8)(L)_(16)]·2HL(HL@AlOC-166,HL=4-Iodobenzoic acid)and[Al_(8)(OH)_(8)(L)_(8)(L1)_(8)]·2DMF(DMF@AlOC-166,HL1=isoamyl alcohol),are acquired by introducing different types of guest components based on the internal pore cavities of the aluminum molecular ring[Al_(8)(OH)_(8)(L)_(16)](AlOC-166).The inclusion of these guests is attributed to the presence of abundant hydrophilic OH serving as the hydrogen bond donors inward the ring ***-guest compounds usually exhibit superior nonlinear optical(NLO)response due to the existence of guest molecules that could change symmetry,dipole moments,charge distributions,***,the AlOC-166 achieved the best NLO results,although it had no guest molecules inside its molecular ring,which breaks the traditional *** reason for this trend can be explained by the difference in intermolecular force rather than intramolecular interaction,mainly related to the amount and strength ofπ···πand C—I···πinteractions in different *** work investigates the effect of host-guest interaction on NLO,representing a new perspective for designing optical limiting materials.

关键词： Host-guest chemistry Noncovalent interaction Nonlinear optical Aluminum molecular ring

Single neuron network PI control of high reliability linear induction motor for Maglev

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第3期8卷 408-411页

作者： fang You-tong FAN cheng-zhi College of Electrical Engineering Zhejiang University Hangzhou 310027 China

The paper deals with a new model of linear induction motor (LIM) to improve the reliability of the system. Based on the normal equation circuit of LIM considering the dynamic end effect, an equivalent circuit model with compensation of large end effect is constructed when the end effect force at synchronism is of braking character. The equivalent circuit model is used for secondary-flux oriented control of LIM. Single neuron network PI unit for LIM servo-drive is also discussed. The effectiveness of mathematical model for drive control is verified by simulations.

关键词： Linear induction motor (LIM) Field-oriented control End effect

Electrochemical Studies of Eight New Divalent Transition Metal Benzenesulphonate Ternary Complexes with 1,10-Phenanthroline

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Chemical Research in Chinese Universities 2004年第6期20卷 694-697页

作者： LUYao GUOLi-ping MAJian-fang YANGJin WUDong-mei FacultyofChemistry NortheastNormalUniversityChangchun130024China CollegeofChemistry＆Pharmocology JiamusiUniversityJiamusi154002China

The electrochemical properties of eight new divalent transition metal benzenesulphonate complexes with 1,10-phenanthroline in different solvents and supporting electrolytes were investigated by means of cyclic voltammetry(CV). Based on the CV data the influences of various coordination modes on the electrochemical behavior of the complexes were discussed. The diffusion coefficient D c and rate constant k s of those complexes in DMF systems were estimated according to CV and the results show that these processes were all quasi-reversible.

关键词： Benzenesulphonate 1,10-Phenanthroline Transition metal complex Cyclic voltammetry

Nickel oxide for perovskite tandem solar cells

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Journal of Semiconductors 2024年第11期45卷 1-7页

作者： Ting Nie Yuanhang cheng Zhimin fang Institute of Technology for Carbon Neutralization Yangzhou UniversityYangzhou 225127China School of New Energy Nanjing University of Science and TechnologyJiangyin 214443China School of Materials Science and Engineering Shaanxi Normal UniversityXi’an 710119China National Laboratory of Solid State Microstructures Nanjing UniversityNanjing 210093China

Perovskite tandem solar cells(TSCs)are popular for their ability to surpass the Shockley-Queisser(S-Q)limit of singlejunction solar cells[1-9].Currently,there are mainly four types of perovskite TSCs,including perovsk... 详细信息

关键词： perovskite limit copper

Developing chemical signatures of particulate air pollution in the Pearl River Delta region, China

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Journal of Environmental Sciences 2011年第7期23卷 1143-1149页

作者： mei Zheng Yuan cheng Limin Zeng Yuanhang Zhang College of Environmental Sciences and Engineering Peking University Beijing 100871 China School of Earth and Atmospheric Sciences Georgia Institute of Technology Atlanta GA 30332 USA

PM 2.5 samples were collected in a regional sampling network with three sites in Hong Kong and four sites in the adjacent inland Pearl River Delta （PRD） or Guangdong Province during four months/seasons from 2002–2003. Trans-boundary transport between Hong Kong and the inland PRD is inevitable under the influence of Asian monsoon. In summer, Hong Kong serves as the upwind site of the inland PRD while during other seasons it is under the influence of continental emissions. Previous studies have recognized the importance of using chemical signatures to differentiate local vs. regional contributions to air pollutants in Hong Kong such as the CO/NOx ratio, ratios of different VOC species. In this study, detailed chemical speciation by gas chromatography-mass spectrometry was performed with PM 2.5 samples to identify new chemical signatures to distinguish aerosols in Hong Kong from those from the inland PRD. Since Hong Kong is not influenced by the continental emissions from the inland PRD during summer, comparison focused on chemical data obtained from this season for chemical signatures. The new ratios developed from the current study include LCPI/HCPI ratio of alkanes （0.39 ± 0.02 in Hong Kong vs. 0.78 ± 0.08 in the inland PRD）, pyrene to benzo[ghi]perylene ratio （0.97 ± 0.21 in Hong Kong compared to 0.20 ± 0.06 in the inland PRD）, and the ratio of 1,2-benzenedioic acid to 1,4-benzenedioic acid （1.8 ± 0.1 in Hong Kong vs. 0.6 ± 0.05 in the inland PRD）. Results from this study also revealed that Hong Kong was impacted by ship emissions as reflected by substantially high V/Ni ratio （9 ± 2） while this ratio was about 1–2 at all sites in the inland PRD, which is very close to typical ratios from residual oil combustion.

关键词： PM 2.5 chemical signature local and regional air pollution Hong Kong Pearl River Delta

A maximum a posteriori super resolution algorithm based on multidimensional Lorentzian distribution

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第12期10卷 1705-1713页

作者： Wen CHEN Xiang-zhong fang Yan cheng Shanghai Key Lab of Digital Media Processing and Transmissions Institute of Image Communication and Information Processing Shanghai Jiao Tong University Shanghai 200240 China College of Information Technology East China University of Political Science and Law Shanghai 201620 China

This paper presents a threshold-free maximum a posteriori (MAP) super resolution (SR) algorithm to reconstruct high resolution (HR) images with sharp edges. The joint distribution of directional edge images is modeled as a multidimensional Lorentzian (MDL) function and regarded as a new image prior. This model makes full use of gradient information to restrict the solution space and yields an edge-preserving SR algorithm. The Lorentzian parameters in the cost function are replaced with a tunable variable, and graduated nonconvexity (GNC) optimization is used to guarantee that the proposed multidimensional Lorentzian SR (MDLSR) algorithm converges to the global minimum. Simulation results show the effectiveness of the MDLSR algorithm as well as its superiority over conventional SR methods.

关键词： Edge preservation Multidimensional Lorentzian distribution (MDL) Super resolution Threshold

Manufacturing Error Effects on Mechanical Properties and Dynamic Characteristics of Rotor Parts under High Acceleration

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Chinese Journal of Mechanical Engineering 2017年第4期30卷 920-932页

作者： mei-Hui Jia cheng-Lin Wang Bin Ren School of Logistics Beijing Wuzi UniversityBeijing 101149China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Stress, strain and vibration characteristics of rotor parts should be changed significantly under high acceleration, manufacturing error is one of the most important reason. However, current research on this prob- lem has not been carried out. A rotor with an acceleration of 150,000 g is considered as the objective, the effects of manufacturing errors on rotor mechanical properties and dynamic characteristics are executed by the selection of the key affecting factors. Through the force balance equation of the rotor infinitesimal unit establishment, a theoretical model of stress calculation based on slice method is pro- posed and established, a formula for the rotor stress at any point derives. A finite element model （FEM） of rotor with holes is established with manufacturing errors. The chan- ges of the stresses and strains of a rotor in parallelism and symmetry errors are analyzed, which verify the validity of the theoretical model. The pre-stressing modal analysis is performed based on the aforementioned static analysis. The key dynamic characteristics are analyzed. The results demonstrated that, as the parallelism and symmetry errors increase, the equivalent stresses and strains of the rotor slowly increase linearly, the highest growth rate does not exceed 4%, the maximum change rate of natural frequency is 0.1%. The rotor vibration mode is not significantlyaffected. The FEM construction method of the rotor with manufacturing errors can be utilized for the quantitative research on rotor characteristics, which will assist in the active control of rotor component reliability under high acceleration.

关键词： High acceleration Rotor Manufacturingerror Stress and strain Dynamic characteristics