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electrostatic attraction caused by triboelectrification in climbing geckos

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Friction 2022年第1期10卷 44-53页

作者： Yi SONG Zhouyi WANG Yang LI Zhendong DAI College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Adhesion achieved through feet setae is fundamental for gecko agilely *** diverse hypotheses have been proposed,none of them thoroughly explains the setae function,implying a kind of hybrid-mechanism-based adhesion in *** addition to van der Waals interactions and capillary force,the electrostatic attraction that emerges from triboelectrification was suggested as a component of setae ***,the contribution by electrostatic attraction to the total setae attachment is still *** this study,we analyzed the occurrence of electrostatic attraction at gecko setae through experiments and model *** touching the substrates with only~1/70th of the foot area,freely wall-climbing geckos developed tribocharge at their feet setae with a density of~277 pC/mm^(2),generating electrostatic attractions with a strength of~4.4 mN/mm^(2).From this perspective,the adhesion driven by triboelectrification could account for about 1%of total *** analyses at spatula level indicated a similar result showing that the electrostatic force might account for~3%of the adhesion that facilitates wall-climbing in *** low contribution of the electrostatic force partly explains why geckos always face difficulty in maneuvering onto those substrates(e.g.,teflon)where they could easily develop tribocharge but difficultly generate van der Waals ***,long-range electrostatic forces may play other roles in a distance range where the van der Waals interaction cannot *** findings not only add to our understanding of the mechanism of gecko adhesion,but also will help us advance gecko-inspired fibular adhesives.

关键词： gecko attraction electrostatic

electrostatic Surface Trap for Cold Polar Molecules with a Charged Circular Wire

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Chinese Physics Letters 2007年第5期24卷 1228-1230页

作者：马慧周蓓廖斌印建平 Key Laboratory for Optical and Magnetic Resonance Spectroscopy (Ministry of Education) Department of Physics East China Normal University Shanghai 200062

We propose a novel scheme to trap cold polar molecules on the surface of an insulating substrate （i.e. a chip） by using an inhomogeneous electrostatic field, which is generated by the combination of a circular charged wire （a ring electrode） and a grounded metal plate. The spatial distributions of the electrostatic field from the above charged wire layout and its Stark potentials for CO molecules are calculated. Our study shows that when the voltage applied to the wire is U = 15 kV, a ring radius is R = 5 mm, the thickness of the insulating substrate is b = 5 mm, and a wire radius is r = 1mm, the maximum efficient trapping potential （i.e., as equivalent temperature） for CO molecules is greater than 141.7mK, which is high enough to trap cold polar molecules with a temperature of 50 mK in the low-field-seeking states.

关键词： electrostatic Molecules Circular

electrostatic Levitation of Plant Seeds and Flower Buds

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Chinese Physics Letters 2012年第6期29卷 125-128页

作者： HU Liang WANG Hai-Peng LI Liu-Hui WEI Bing-Bo Department of Applied Physics Northwestern Polytechnical UniversityXi’an 710072

We report the electrostatic levitation of various kinds of seeds and flower *** berry and pepper near a spherical shape show a stable levitation *** prolate ellipsoid soybeau and flower buds are always “standing” in the free space with satisfactory levitation *** the irregular mushroom and wheat grain,the levitation state is characterized as a “top-heavy” *** special stable equilibrium states are proved by the analysis of surface charge *** obtained saturation polarization charge of samples presents a good accordance with experimental *** levitation ability is weighed by thefactor m(ε_(r) + 2) / (εrD^(2)).

关键词： grain charge electrostatic

electrostatic-lenses position-sensitive TOF MCP detector for beam diagnostics and new scheme for mass measurements at HIAF

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Nuclear Science and Techniques 2019年第10期30卷 63-73页

作者： Jun-Hao Liu Zhuang Ge Qian Wang Geng Wang Li-Na Sheng Wen-Wen Ge Xing Xu Peng Shuai Qi Zeng Bo Wu University of Chinese Academy of Sciences Beijing 100049China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear Science and Engineering East China University of TechnologyNanchang 330013China

A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in *** by low energy loss and good performances of timing and position measurements,it would be located at focal planes in fragment separator HFRS for position monitoring,beam turning,Bq measurement,and trajectory ***,it will benefit the building-up of a magnetic-rigidity–energy-loss–time-offlight(BqDETOF)method at HFRS for high-precision in-flight particle identification of radioactive isotope beams on an event-by-event *** importantly,the detector can be utilized for in-ring TOF and position measurements,beam-line TOF measurements at two achromatic foci,and position measurements at a dispersive focus of HFRS,thus making it possible to use two complementary mass measurement methods[isochronous mass spectrometry at the storage ring SRing and magnetic-rigidity–time-of-flight(BqTOF)at the beam-line HFRS]in one single experimental run.

关键词： Microchannel plate electrostatic lenses Detector Position-sensitive Time-of-flight Mass measurements HIAF

electrostatic interaction mechanism on the separation of phenols by non-aqueous capillary electrophoresis

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Science China Chemistry 2007年第1期50卷 47-53页

作者： WEI WeiLi YIN YongGuang XIA ZhiNing CHEN ZhiTao LIU WeiQi Department of Pharmaceutics College of Chemistry and Chemical EngineeringChongqing UniversityChongqing 400044China Research Center for Eco-Environmental Science Chinese Academy of SciencesBeijing 100081China Key Laboratory for Biomechanics&Tissue Engineering of Ministry of Education Chongqing UniversityChongqing 400044China

The electrostatic interaction between additive and analyte is of great importance to non-aqueous cap- illary electrophoresis(NACE)*** tetraalkylammonium bromides and acetonitrile were applied as additives and running solvent *** effect of alkyl chain length and concentra- tion of additive on electrostatic interactions was investigated by the separation of *** sepa- ration ability was found to increase with decreasing alkyl chain length of the additive,and the resolu- tion values were increased with increasing additive *** separation was seriously dete- riorated after a little amount of water was added in the running ***,the electrostatic interaction is strong under the conditions of low electron cloud density,weak steric hindrance and multi-interaction ***,the separation result can be predicted by theoretical analysis,which is helpful for the separation of other substances in NACE based on electrostatic interaction.

关键词： non-aqueous capillary electrophoresis electrostatic interaction tetraalkylammoniums phenol compounds

Two types of highly efficient electrostatic traps for single loading or multi-loading of polar molecules

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Chinese Physics B 2020年第4期29卷 284-291页

作者： Bin Wei Hengjiao Guo Yabing Ji Shunyong Hou Jianping Yin State Key Laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200062China

Two novel electrostatic traps named octopole-based disk electrostatic trap(ODET)and tubular-based disk electrostatic trap(TDET)are proposed for trapping cold polar molecules in low-field-seeking *** MgF as the target molecule,single loading and multi-loading methods are numerically simulated with varied incident velocities of slow molecular beams in the two types of traps,*** ODET,with an incident velocity of 10 m/s,a highest loading efficiency of 78.4% or 99.9% has been achieved under the single loading or multi-loading operation *** TDET,with an incident velocity of 11 m/s,a highest loading efficiency of 81.6% or 106.5% has been achieved using the two loading methods,*** such high loading efficiencies,the trapped cold molecules can be applied in the researches of cold collisions,high precision spectroscopy,and precision ***,together with a blue-detuned hollow beam,the new electrostatic traps proposed here offer a new platform for the following gradient-intensity cooling of MgF molecules,which may provide a new way to produce high density ultracold molecules.

关键词： cold molecules electrostatic trapping Monte Carlo simulations

Harnessing electrostatic Interactions for Enhanced Conductivity in Metal-Organic Frameworks

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Research 2021年第1期2021卷 1543-1553页

作者： An-An Zhang Xiyue Cheng Xu He Wei Liu Shuiquan Deng Rong Cao Tian-Fu Liu Department of Chemistry School of Chemistry and Materials ScienceUniversity of Science and Technology of ChinaHefeiAnhui 230026China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian 350002China University of the Chinese Academy of Sciences Beijing 100049China

The poor electrical conductivity of metal-organic frameworks(MOFs)has been a stumbling block for its applications in many important ***,exploring a simple and effective strategy to regulate the conductivity of MOFs is highly ***,anionic guest molecules are incorporated inside the pores of a cationic MOF(PFC-8),which increases its conductivity by five orders of magnitude while maintaining the original *** contrast,the same operation in an isoreticular neutral framework(PFC-9)does not bring such a significant *** studies reveal that the guest molecules,stabilized inside pores through electrostatic interaction,play the role of electron donors as do in semiconductors,bringing in an analogous n-type semiconductor mechanism for electron ***,we demonstrate that harnessing electrostatic interaction provides a new way to regulate the conductivity of MOFs without necessarily altering the original porous *** strategy would greatly broaden MOFs’application potential in electronic and optoelectronic technologies.

关键词： structure conductivity electrostatic

Unraveling the nature of sensing in electrostatic MEMS gas sensors

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Microsystems & Nanoengineering 2024年第3期10卷 109-117页

作者： Yasser S.Shama Sasan Rahmanian Hamza Mouharrar Rana Abdelrahman Alaaeldin Elhady Eihab M.Abdel-Rahman Systems Design Engineering University of Waterloo200 University Ave WWaterloo N2L 3G1 ONCanada Mechanical Engineering Benha Faculty of EngineeringBenha UniversityBenha 13511Egypt

This paper investigates the fundamental sensing mechanism of electrostatic MEMS gas *** compares among the responsivities of a set of MEMS isopropanol sensors before and after functionalization,and in the presence and absence of electrostatic fields when operated in static and dynamic detection *** the static mode,we found that the sensors do not exhibit a measurable change in displacement due to added *** the other hand,bare sensors showed a clear change in displacement in response to isopropanol *** the dynamic mode,functionalized sensors showed a measurable frequency shift due to the added mass of isopropanol *** the presence of strong electrostatic fields,the measured frequency shift was found to be threefold larger than that in their absence in response to the same concentration of isopropanol *** enhanced responsivity of dynamic detection allows the sensors to measure the vapor mass captured by the functional material,which is not the case for static *** detection of isopropanol by bare sensors in static mode shows that change in the medium permittivity is the primary sensing *** enhanced responsivity of dynamic mode sensors when operated in strong electrostatic fields shows that their sensing mechanism is a combination of a weaker added mass effect and a stronger permittivity *** findings show that electrostatic MEMS gas sensors are independent of the direction of the gravitational field and are,thus,robust to changes in *** is erroneous to refer to them as‘gravimetric’sensors.

关键词： mechanism electrostatic measurable

Dynamic characteristics of charged droplets in an electrostatic spraying process with twin capillaries

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Chinese Journal of Chemical Engineering 2018年第12期26卷 2403-2411页

作者： Jun Zhang Hongzhou He Guanxing Huang Cleaning Combustion and Energy Utilization Research Center of Fujian Province School of Mechanical Engineering Jimei University Engineering training Centre Jimei University

The experimental and simulated investigations on electrostatic spraying with twin capillaries are carried out. The starting electric voltage required for the cone-jet and the deposition characteristics of the droplets are *** whole spraying process, which includes jet and droplet motions, is simulated and the simulated results on the motions of jet and droplet are basically consistent with the experiments. According to the simulated results,the contributions of various electric forces to droplet movement are quantitatively analyzed and the droplet dynamic characteristics, especially the interaction mechanism between two sprays, are revealed. The test results on the droplet deposition characteristics partially support the simulated results on the droplet motion. The present work is useful for a better understanding on the interaction between sprays in double or multi-capillary system.

关键词： electrostatic spray Twin capillaries Simulation Interaction