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Theoretical framework and experimental solution for the air-water interface adsorption problem in cryoEM

Biophysics Reports 2023年第4期9卷 215-229页

作者： joon s.kang Xueting Zhou Yun-Tao Liu Kaituo Wang Z.Hong Zhou Department of Microbiology Immunology & Molecular Genetics University of California Los Angeles (UCLA) Molecular Biology Institute UCLA California Nano systems Institute UCLA

As cryogenic electron microscopy(cryoEM) gains traction in the structural biology community as a method of choice for determining atomic structures of biological complexes, it has been increasingly recognized that many complexes that behave well under conventional negative-stain electron microscopy tend to have preferential orientation, aggregate or simply mysteriously “disappear” on cryoEM grids. However, the reasons for such misbehavior are not well understood, which limits systematic approaches to solving the problem. Here, we have developed a theoretical formulation that explains these observations. Our formulation predicts that all particles migrate to the air–water interface(AWI)to lower the total potential surface energy-rationalizing the use of surfactant, which is a direct solution to reduce the surface tension of the aqueous solution. By performing cryogenic electron tomography(cryo ET) on the widely-tested sample, Gro EL, we demonstrate that, in a standard buffer solution, nearly all particles migrate to the AWI. Gradually reducing the surface tension by introducing surfactants decreased the percentage of particles exposed to the surface. By conducting single-particle cryoEM, we confirm that suitable surfactants do not damage the biological complex, thus suggesting that they might provide a practical, simple, and general solution to the problem for high-resolution cryoEM. Applying this solution to a real-world AWI adsorption problem involving a more challenging membrane protein,namely, the Cl C-1 channel, has resulted in its near-atomic structure determination using cryoEM.

关键词： surface energy surfactant sample preparation CryoEM CryoET Air–water interface adsorption

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Emission wavelength selection via anomalous polarized fluorescence in ZnO-C nanowires

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Nano Research 2024年第5期17卷 4489-4497页

作者： joon Kiat kang Kim Yong Lim Chorng Haur sow Department of Physics National University of SingaporeSingapore 117542Singapore

Defect fluorescence from high aspect ratio semiconductor nanowires typically displays a weak polarization parallel to the nanowire’s long axis due to dielectric mismatch in high aspect ratio ***,anomalous 2.2 eV defect fluorescence distinctly polarized perpendicular to the nanowire is observed and measured from carbon-incorporated zinc oxide *** observations are significant because polarized defect emissions with consistent polarization on a mesoscopic scale are *** a systematic study and comparison of experimental results with density functional theory calculations,an oriented defect complex comprising carbon substituting on an oxygen site and an oxygen vacancy(CO-VO)is deduced to be responsible for the anomalous yellow fluorescence,demonstrating a method for relating atomic-scale defect geometry to mesoscopic *** anomalous emission can appear in both green-and red-fluorescing nanowires grown with different carbon concentrations,verifying the independence and uniqueness of the 2.2 eV *** allows for polarization-dependent emission wavelength selection from a single nanowire.

关键词： anomalous polarization defects fluorescence zinc oxide carbon

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An Elliptic Nonlinear system of Two Functions with Application

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Journal of Partial Differential Equations 2023年第2期36卷 122-146页

作者： kang joon Hyuk ROBERTsON Timothy Department of Mathematics Andrews UniversityBerrien Springs MI.49104-0350U.S.A Department of Mathematics University of TennesseeKnoxville TN.37996-1320U.S.A

The purpose of this paper is to give a sufficient conditions for the existence and uniqueness of positive solutions to a rather general type of elliptic system of the Dirichlet problem on a bounded domain Ω in R^(n).Also considered are the effects of perturbations on the coexistence state and *** techniques used in this paper are super-sub solutions method,eigenvalues of operators,maximum principles,spectrum estimates,inverse function theory,and general elliptic *** arguments also rely on some detailed properties for the solution of logistic *** results yield an algebraically computable criterion for the positive coexistence of competing species of animals in many biological models.

关键词： Competition system coexistence state

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Comprehensive analysis of two-dimensional charge transport mechanism in thin-film transistors based on random networks of single-wall carbon nanotubes using transient measurements

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Nano Research 2022年第2期15卷 1524-1531页

作者： Hyeonwoo shin sang-joon Park Byeong-Cheol kang Tae-Jun Ha Department of Electrical Engineering and Computer science Inter-university Semiconductor Research CenterSeoul National UniversitySeoul 08826Korea Department of Electronic Materials Engineering Kwangwoon UniversitySeoul 01897Korea

Understanding charge transport mechanisms in thin-film transistors based on random networks of single-wall carbon nanotubes(sWCNT-TFTs)is essential for further advances to improve the potential for various nanoelectronic ***,a comprehensive investigation of the two-dimensional(2D)charge transport mechanism in sWCNT-TFTs is reported by analyzing the temperature-dependent electrical characteristics determined from the direct-current and non-quasi-static transient measurements at 80-300 *** elucidate the time-domain charge transport characteristics of the random networks in the sWCNTs,an empirical equation was derived from a theoretical trapping model,and a carrier velocity distribution was determined from the differentiation of the transient ***,charge trapping and de-trapping in shallow-and deep-traps in sWCNT-TFTs were analyzed by investigating charge transport based on their trapping/de-trapping *** comprehensive analysis of this study provides fundamental insights into the 2D charge transport mechanism in TFTs based on random networks of nanomaterial channels.

关键词： single-wall carbon nanotube random networks two-dimensional(2D)charge transport time-domain transient measurements charge trapping/de-trapping shallow-/deep-traps

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A metallic anti-biofouling surface with a hierarchical topography containing nanostructures on curved micro-riblets

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Microsystems & Nanoengineering 2022年第1期8卷 83-96页

作者： Taekyung Kim sunmok Kwon Jeehyeon Lee joon sang Lee shinill kang National Center for Optically-assisted high precision Mechanical systems Yonsei UniversitySeoul 03722Korea school of Mechanical Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul 03722Korea

Metallic surface finishes have been used in the anti-biofouling,but it is very difficult to produce surfaces with hierarchically ordered *** the present study,anti-biofouling metallic surfaces with nanostructures superimposed on curved micro-riblets were produced via top-down *** to the attachment theory,these surfaces feature few attachment points for organisms,the nanostructures prevent the attachment of bacteria and algal zoospores,while the micro-riblets prohibit the settlement of *** oxidation was performed to induce *** forms a hydration layer on the surface,which physically blocks foulant adsorption along with the anti-biofouling *** characterized the surfaces via scanning electron and atomic force microscopy,contact-angle measurement,and wear-resistance *** contact angle of the hierarchical structures was less than 1°.Laboratory settlement assays verified that bacterial attachment was dramatically reduced by the nanostructures and/or the hydration layer,attributable to *** micro-riblets prohibited the settlement of *** 77 days of static immersion in the sea during summer,the metallic surface showed significantly less biofouling compared to a surface painted with an anticorrosive coating.

关键词： Anti-biofouling superhydrophilic Hierarchical topography Metallic engineered surface Nanoimprinting,static immersion test,field trials

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Low-Programmable-Voltage Nonvolatile Memory Devices Based on Omega-shaped Gate Organic Ferroelectric P(VDF-TrFE) Field Effect Transistors Using p-type silicon Nanowire Channels

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Nano-Micro Letters 2015年第1期7卷 35-41页

作者： Ngoc Huynh Van Jae-Hyun Lee Dongmok Whang Dae joon kang Department of Physics Institute of Basic SciencesSungkyunkwan University school of Advanced Materials science and Engineering SKKU Advanced Institute of Nanotechnology Sungkyunkwan University

A facile approach was demonstrated for fabricating high-performance nonvolatile memory devices based on ferroelectric-gate field effect transistors using a p-type si nanowire coated with omega-shaped gate organic ferroelectric poly(vinylidene fluoride-trifluoroethylene)(P(VDF-Tr FE)). We overcame the interfacial layer problem by incorporating P(VDF-Tr FE) as a ferroelectric gate using a low-temperature fabrication process. Our memory devices exhibited excellent memory characteristics with a low programming voltage of ±5 V, a large modulation in channel conductance between ON and OFF states exceeding 105, a long retention time greater than 3 9 104 s, and a high endurance of over 105 programming cycles while maintaining an ION/IOFFratio higher than 102.

关键词： si nanowires Field effect transistor Ferroelectric memory

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Electrophoretic Deposition of Oxide Nanoparticles for Electron Emission Enhancement

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Journal of Materials science & Technology 2010年第11期26卷 1032-1036页

作者： Jong Rok Ahn Gil seon kang Hwack Joo Lee Chang joon Park Korea Research Institute of standards and science

Four oxide nanoparticles,such as yttrium oxide,lanthanum oxide,cerium oxide and zirconium oxide were coated on rhenium filaments by an electrophoretic deposition *** oxide coatings were examined by scanning electron microscopy,and electron emission characteristics of the oxide-coated rhenium were studied to find alternative oxide materials for replacing the hazardous thorium *** four oxides tested in this work,yttrium oxide and lanthanum oxide coated rhenium showed enhanced electron emission compared with an uncoated ***,lanthanum oxide coating evaporated too quickly in a vacuum chamber,and hence yttrium oxide was found to be the only alternative material for use in a routine mass *** optimum coating thickness of the yttrium oxide and lanthanum oxide was around 20 μm.

关键词： Electrophoretic deposition Oxide nanoparticles scanning electron microscopy (sEM) Electron emission

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Olfactory Response of Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) to Volatiles Emitted by Mungbean Plants

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Agricultural sciences in China 2011年第4期10卷 560-565页

作者： BAI shu-xiong WANG Zhen-ying HE kang-lai Im Dae-joon state Key Laboratory of Plant Diseases and Insect Pests Institute of Plant Protection Chinese Academy of Agricultural Sciences Beijing 100193 P.R.China National Crop Experiment station Rural Development Administration Suwon 441-100 Republic of Korea

Intercropping maize with the prostrate variety of mungbean, Vigna radiata （L.） Wilczek which grows flat along the ground can increase parasitism of the eggs of the Asian corn borer, Ostrinia furnacalis （Guenée）, a crucial insect pest of maize in China, by Trichogramma ostriniae Pang Chen. This study investigated the behavioural responses of T. ostriniae to plant volatiles emitted from whole plants, leaves, and flowers of prostrate and erect varieties of mungbean in a 4-armed olfactometer. Female parasitiods were significantly attracted to the odours from some varieties of prostrate mungbean when the visit duration and the number of visits were considered, but were not attracted to the odours from any erect varieties. The attractive odours were shown to emanate from the leaves, rather than from the flowers of prostrate mungbean plants. These results have implications for the augmentation of Trichogramma parasitoids in bio-control of O. furnacalis and other crop pests.

关键词： Trichogramma ostriniae olfactory response Vigna radiata plant volatile

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Modeling and Design of H-Infinity Controller for Piezoelectric Actuator LIPCA

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Journal of Bionic Engineering 2010年第2期7卷 168-174页

作者： Gigun Lee Kwanwoo You Taesam kang Kwang joon Yoon Jeong Oog Lee Jung Keun Park Department of Aerospace Information Engineering Konkuk University

We proposed a dynamic model identification and design of an H-Infinity （i.e.H） controller using a LightweightPiezo-Composite Actuator （LIPCA）.A second-order dynamic model was obtained by using input and output data, and applyingan identification *** identified model coincides well with the real *** reduce the resonating mode that istypical of piezoelectric actuators, a notch filter was used.A feedback controller using the Hcontrol scheme was designed basedon the identified dynamic model; thus, the LIPCA can be easily used as an actuator for biomemetic applications such as artificialmuscles or macro/micro positioning in *** control algorithm was implemented using a microprocessor, analogfilters, and power amplifying *** simulation and experimental results demonstrate that the proposed control algorithmworks well in real environment, providing robust performance and stability with uncertain disturbances.

关键词： piezoelectric actuator model identification H-infinity controller biomimetic artificial muscle LIPCA

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A new species of Zanclognatha Lederer and three new records of the families Erebidae and Noctuidae(Lepidoptera,Noctuoidea)from Korea,with notes on larval feeding habits

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Journal of Forestry Research 2021年第3期32卷 1235-1240页

作者： kang-Won Lee joon-Mo Koo Jae-Dong Kim Hui-Lin Han Kyu-Tek Park Holoce Ecosystem Conservation Research Institution HoengseongGangweon Province 225-841Republic of Korea Department of Plant Medicine Chungbuk National UniversityCheongju28644Republic of Korea Department of Applied Biology College of Agriculture and Life ScienceChungnam National UniversityDaejeon 34134Republic of Korea school of Forestry Northeast Forestry UniversityHarbin 150040China Key Laboratory of sustainable Forest Ecosystem Management-Ministry of Education Northeast Forestry UniversityHarbin 150040People’s Republic of China Bioresource and Environmental Center Incheon National UniversityIncheon 22012Republic of Korea

A new species of Zanclognatha Lederer,1857 of the family Erebidae,*** sp.n.,one species of Family Erebidea,Asota egens(Walker,1854)and two species of Family Noctuidae:Meganephria retinea Gyulai and Ronkay,1999 and Amphipyra subrigua Bremer and Grey,1853,are reported for the first time from *** addition,larval feeding habits with their host plants for three species are newly recognized from *** of adults,larvae for Zanclognatha querciella and Meganephria retinea,and the genitalia of male or female for all species are provided.

关键词： Host plants New species New records Korean peninsula Taxonomy

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