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Atomic force microscopy studies of SrTiO_(3.(001)substrates treated by chemical etching and annealing in oxygen

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Science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 459-468页

作者： WANG Xu1, FEI Yiyan1, LU Huibin1, JIN Kui-juan1, ZHU Xiangdong1,3. CHEN Zhenghao1, ZHOU Yueliang1 & YANG Guozhen1 1. beijing National Laboratory for condensed {2. Physics,{3. of Physics,Chinese academy of sciences,beijing 100080,china 2. Department of Physics,University of California, Davis,California,USA beijing National Laboratory for condensed {2. Physics Institute of Physics Chinese Academy of Sciences Beijing China Department of Physics University of California Davis USA

The SrTiO3.(001) substrates treated by chemical etching in NH4F-buffered HF solution and annealing in oxygen ambient have been studied by an atomic force microscopy (AFM). The SrTiO3.substrates with TiO2.termineted and atomically smooth surfaces and single unit cell steps have been obtained. The surface morphologies of SrTiO3.substrates strongly depend on the treated conditions and the quality of the substrates.

关键词： SrTiO3. AFM, surface morphology, surface defects.

Pressure-induced crystallite breaking in La_(0.7)Sr_(0.3.Mn_(0.9)Fe_(0.1)O_3.nanosolids

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Chinese Science Bulletin 1998年第6期43卷 458-461页

作者： ZHENG Fanlei 1, 2. SUI Yu 1, 3. XU Dapeng 1 and SU Wenhui 1, 4 1. Department of Physics, Jilin University, Changchun 13.02., china 2. Changchun institute of Physics, Chinese {2. of sciences, Changchun 13.02., china 3. institute of Metal R Department of Physics Jilin University Changchun Chinas Changchun institute of Physics Chinese Academy of Sciences Changchun China institute of Metal Research Chinese Academy of Sciences Shenyang China International center for Materials Physics Chinese Academy of Sceinces Shenyang China center for condensed {2. and Radiation Physics CCAST (World Lab.) Beijing China

In the compacting process of the La 0.7Sr 0.3.n 0.9Fe 0.1O 3.nanosolids under the pressure range of 0.0-4.5 GPa, the apparent pressure-induced crystallite breaking phenomenon in these nanosolids was observed. With increasing pressure up to 4.5 GPa, the average grain size decreases by 46% while the magnetization of nanosolids decrease by 40% and their coercive increases by 3.%. This kind of breaking has a close relation to the existence of oxygen deficiency in La 0.7Sr 0.3.n 0.9Fe 0.1O 3.nanoparticles. A simple and convenient method for preparing the bulk nanosolids with a large number of clean interfaces has been suggested.

关键词： nanosolid pressure-induced breaking high pressure.

Temporal-spatial variations of euphotic depth of typical lake regions in Lake Taihu and its ecological environmental significance

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Science china Earth sciences 2006年第4期49卷 431-442页

作者： ZHANG Yunlin1, 2. QIN Boqiang1, HU Weiping1, WANG Sumin1, CHEN Yuwei1 & CHEN Weimin1 1. Nanjing institute of Geography & Limnology, Chinese academy of {2., Nanjing 2.0008, china 2. Graduate School of the Chinese academy of {2., beijing 10003., china Nanjing institute of Geography & Limnology Chinese Academy of Sciences Nanjing China Graduate School of the Chinese academy of sciences Beijing China

By using the data of underwater irradiance measured in the different lakeregions of Lake Taihu during 1998—2.04 and total suspended solids (TSS), wind speeds of the total13.stations in typical lake regions during 1993.2.03. this paper analyzes the factors ofinfluencing on PAR (pho-tosynthetically available radiation) attenuation, euphotic depth, andpresents the temporal and spatial variations of euphotic depth of typical lake regions in LakeTaihu, and the spectral distributions of euphotic depth at station 2. The results show that theconcentration of TSS is the most important factor impacting PAR attenuation, followed by chlorophylla; chromophoric dissolved organic {3. (CDOM) has little impact on the PAR euphotic depth. During1993.2.03. the mean yearly PAR euphotic depths of the typical lake regions ranged from 1.04 to1.95 m with a mean value of 1.3.±0.2. m. The PAR euphotic depth fell into 3.spatial zone types:Type Ⅰ, the lowest, including the lake center and the inflows of rivers; Type Ⅱ, intermediate,including Meiliang Bay, Wulihu Lake and Gonghu Bay; Type Ⅲ, the greatest, including the East LakeTaihu; corresponding mean depths were approximately 1.1, 1.4, 2.0 m, respectively. The seasonalvariations of euphotic depths were not quite the same in different lake regions. In the lake center,the mean values of PAR euphotic depth in summer and autumn were significantly greater than those inwinter and spring; in the Meiliang Bay, winter means were significantly greater than in the otherthree seasons; in the East Lake Taihu, winter means were significantly less than in the other threeseasons. However, no distinct seasonal change was recorded in the Wulihu Lake, Gonghu Bay and theinflows of rivers. The spectral distributions of euphotic depth present a minimal value at the bluelight wave band of 400 nm, and a peak at the green light wave band of around 580 nm. In 1998 and1999, based on the seasonal many-day continuous measurements, the PAR euphotic depths at station 2.

关键词： lake taihu euphotic depth diffuse attenuation coefficient total suspendedsolid ecological

Magnetic Field Effects on Quantum-Dot Spin Valves

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Communications in Theoretical Physics 2009年第3期51卷 555-562页

作者： GAO Jin-Hua,~1 SUN Qing-Feng,~1 and XIE Xin-Cheng~(1,2.1 beijing National Lab for condensed {2. Physics and institute of Physics, Chinese academy of sciences,beijing 100080, china2.Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, USA beijing National Lab for condensed {2. Physics and {3. of Physics Chinese Academy of Sciences Beijing 100080 China Department of Physics Oklahoma State University Stillwater Oklahoma 74078 USA

We study the magnetic field effects on the spin-polarized transport of the quantum dot (QD) spin valve inthe sequential tunneling regime. A set of generalized master equation is derived. Based on that, we discuss the collinearand noncollinear magnetic field effects, respectively. In the collinear magnetic field case, we find that the Zeeman splittingcan induce a negative differential conductance (NDC), which is quite different from the one found in previous *** has a critical polarization in the parallel arrangement and will disappear in the antiparallel configuration. In thenoncollinear magnetic field case, the current shows two plateaus and their angular dependence is analyzed. Althoughsometimes the two current plateaus have similar angular dependence, their mechanisms are different. Our formalism isalso suitable for calculating the transport in magnetic molecules, in which the spin splitting is induced not by a magneticGeld but by the intrinsic magnetization.

关键词： spin value spintronics quantum dot

Single-molecule studies of DNA by molecular combing

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Progress in Natural Science:Materials International 2007年第5期17卷 493-499页

作者： Liu Yuying, Wang Pengye and Dou Shuoxing (College of Science, china Agricultural University, beijing 100083. china Laboratory of Soft {3. Physics, beijing National Laboratory for condensed {3. Physics, institute of Physics, Chinese academy of sciences, beijing 100080, china) College of sciences China Agricultural University Beijing 100083 China Laboratory of Soft matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China beijing National Laboratory for condensed {2. Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China

Molecular combing is a powerful method for aligning a large array of DMA molecules onto a surface. It is a process whereby DNA molecules are stretched and aligned on a glass surface by the force via fluid flow. The ability to comb up to several hundred DNAs on a single cover slip allows for a statistically significant number of measurements to be made. These features make molecular combing an attractive tool for genomic studies, such as DNA replication, DNA transcription, DNA-protein interaction and so on. In this review article, we discuss the molecular combing principle, method and its applications.

关键词： DNA molecule molecular combing DNA-protein interaction.

New quantum tunneling steps in Mn_(11)Cr/Mn_(12. mixed crystal

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Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1769-1771页

作者： ZHOU YuRong1,LI YanRong1,FAN ZhenJun2.& WANG YunPing1 1beijing National Laboratory for condensed {2. Physics,institute of Physics,Chinese academy of sciences,beijing 100190,china 2.chool of Materials sciences and Technology,china University of Geosciences,beijing 43.074,china beijing National Laboratory for condensed {2. Physics Institute of Physics Chinese Academy of Sciences Beijing China School of Materials sciences and Technology China University of Geosciences Beijing China

Magnetic properties of Mn11Cr and Mn12.mixed crystal at low temperature are studied.A new set of quantum tunneling steps discovered in magnetization curves suggests that there may exist another kind of single molecula... 详细信息

关键词： quantum tunneling molecular magnet magnetization curve

Electric-stimulus rate encoding algorithm of Mandarin tonal information in cochlear implant

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Progress in Natural Science:Materials International 2006年第12期16卷 1315-1321页

作者： GUAN Tian~1, GONG Qin~1 and YE Datian~2.*(1. Department of Biomedical Engineering, Tsinghua University, beijing 100084, china 2. Research {2. of Biomedical Engineering, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, china) Department of Biomedical Engineering Tsinghua University Beijing 100084 China Research center of Biomedical Engineering Graduate School Shenzhen Tsinghua University Shenzhen 518055 China

The modern multi-channel cochlear implants usually extract and encode the temporal envelope cues. This kind of algorithms can hardly satisfy the users who speak tonal languages, such as Mandarin. Many studies have tried to enhance the recognition ability of Mandarin through encoding tonal information and made suggestions to frequency-modulate the fixed pulse-rate carrier with the extracted tonal information based on the rate-pitch theory in electric hearing. However, how to encode and deliver the tonal information such as F_0by changing electric-stimulus rate has not got further study in clinical electric-stimulus mode. The present paper focuses on this matter by piecewise calculating the appreciable electric-stimulus rates. Then an electric-stimulus encoding algorithm of Mandarin tone is brought forward and testified through acoustic simulations. Such conclusion can be drawn that this algorithm of electric-stimulus rate could convey tonal information well and help to enhance the Mandarin speech recognition ability.

关键词： cochlear implant tone fundamental frequency electric-stimulus rate.

High-sensitivity photovoltage based on the interfacial photoelectric effect in the SrTiO_(3.δ)/Si heterojunction

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Science china(Physics,Mechanics & Astronomy) 2010年第11期53卷 2080-2083页

作者： WEN Juan 1,GUO HaiZhong 1,XING Jie 2.Lü HuiBin 1,JIN Kui-Juan 1,HE Meng 1 & YANG GuoZhen 1 1 beijing National Laboratory for condensed {2. Physics,institute of Physics,Chinese academy of sciences,beijing 100190,china 2.School of Materials sciences and Technology,china University of Geosciences,beijing 100083.china beijing National Laboratory for condensed {2. Physics Institute of Physics Chinese Academy of Sciences Beijing China School of Materials sciences and Technology China University of Geosciences Beijing China

A high sensitivity photovoltaic effect has been observed in a heterojunction composed of n-type wide bandgap oxide SrTiO 3.δ and p-type Si fabricated by laser molecular beam *** responsivity of open-circuit photovoltage can reach 10 4 V/W without any amplification under zero bias for the wavelength range from visible to near infrared light in nW-μW *** attribute the high performance of the photovoltage responsivity to the interfacial photoelectric effects in the SrTiO 3.δ /Si *** the experimental results,some ideas can be generalized to improve photovoltaic efficiency and develop high sensitivity photodetectors with wide bandgap oxide materials and Si.

关键词： SrTiO 3.δ/Si heterojunction interfacial photoelectric effect photovoltage

Recent progress in single chip white light-emitting diodes with the InGaN underlying layer

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Science china(Physics,Mechanics & Astronomy) 2010年第3期53卷 445-448页

作者： WANG XiaoLi, WANG XiaoHui, JIA HaiQiang, XING ZhiGang & CHEN Hong beijing National Laboratory of condensed {2., {3. of Physics, Chinese academy of sciences, beijing 100080, china beijing National Laboratory of condensed {2. Institute of Physics Chinese Academy of Sciences Beijing China

Tremendous progress has been achieved in white light-emitting diodes (LEDs). To further improve the quality of white light and simplify the fabrication process, a single chip white-light LED with the InGaN underlying layer (UL) was studied and fabricated. The turn-on voltage of this type of LED was 2.7 V, and the spectrum at a forward bias current of 2. mA was comprised of blue (443.nm) and yellow (563.nm) lights. The intensity ratio of blue to yellow light was almost constant with the in- creasing injection current in a certain scope, most important for the solid state illumination. The useful life test showed the light output level remained at a 90% light output level at the driving current of 40 mA after 3.0 h, meanwhile, the UV and blue LEDs combined with phosphor reached a 2.% value after 144 h within 3.0 h.

关键词： GaN InGaN white light LED MOCVD