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Functionalisation of aligned carbon nanotubes with nitric acid vapour

MIcRO & NANO LETTERS 2011年第8期6卷 704-708页

作者： Shulga, E. Pohako, K. Treshchalov, A. Joost, U. Kisand, V. Kink, I. Univ Tartu Inst Phys EE-51014 Tartu Estonia Univ Tartu Inst Chem EE-50411 Tartu Estonia Estonian Nanotechnol Competence Ctr EE-51014 Tartu Estonia

Millimetre high aligned carbon nanotubes (AcNTs) were functionalised by nitric acid vapour at low temperature with the formation of carbonyl and carboxyl functional groups. Samples were analysed using a scanning electron microscope (SEM), EDX, Fourier transformed infrared (FTIR), Raman and X-ray photoelectron spectroscopy (XPS). Depending on the temperature and reaction time, the treatment can lead to uniform sidewall functionalisation preserving the alignment of the AcNT 'forest', to random destruction, leading to significant modification of the morphology of the AcNT 'forest', or in some cases to cutting off the AcNTs from the substrate. Influence of the treatment duration and temperature on samples morphology and oxygen-to-carbon ratio are discussed.

关键词： crystal growth from vapour infrared spectra c surface morphology vapour deposition Raman spectroscopy treatment duration scanning electron microscopy FTIR millimetre high aligned carbon nanotubes XPS Raman spectra EDX SEM reaction time X-ray photoelectron spectra Infrared and Raman spectra in inorganic crystals oxygen-to-carbon ratio Solid surface structure Photoelectron spectra of semiconductors and insulators carboxyl functional group formation AcNT forest morphology carbon nanotubes scanning electron microscope carbonyl formation Fourier transform spectra Fourier transformed infrared spectroscopy nanofabrication X-ray photoelectron spectroscopy Electron spectroscopy for chemical analysis (photoelectron, Auger spectroscopy, etc.) sidewall functionalisation Methods of nanofabrication and processing

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Equivalent mechanical boundary conditions for single layer graphene sheets

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MIcRO & NANO LETTERS 2016年第5期11卷 248-252页

作者： Sadeghzadeh, Sadegh Iran Univ Sci & Technol Sch New Technol Tehran Iran

To describe and analyse mechanical structures due to external loads, equation of motion must be supplemented with appropriate boundary conditions. When nanomechanical structures (especially layered systems) are considered, satisfying the boundaries is more challenging. It may be essential to develop a specific methodology for any system in such scale and configuration. This work introduces a general approach for boundary conditions of monolayer graphene sheets as the most important part of future sensors and resonators in nanoelectromechanical systems. comparing with the experiments, it has been demonstrated that the graphene sheets on the adhesive surfaces should be assumed as a hinged edge condition and not as a clamped one. As a result, inaccuracy of the commonly used rigid base as a clamped condition is proven due to comparison with a reported experiment. It is suggested that a flexible substrate can be replaced to have better accordance. A flexible silicon base with equilibrium distance equal to s = 2.5 angstrom and depth of potential well equal to epsilon = 0.02 eV is obtained as the best substrate for a square graphene sheet under doubly clamped edge conditions.

关键词： graphene nanomechanics nanoelectromechanical devices monolayers equivalent mechanical boundary conditions external loads equation of motion nanomechanical structures nanoelectromechanical systems adhesive surfaces hinged edge condition flexible silicon base doubly clamped edge conditions monolayer graphene sheets distance 2 5 angstrom c Si

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On the axial vibration of carbon nanotubes with different boundary conditions

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MIcRO & NANO LETTERS 2014年第11期9卷 807-811页

作者： Yayli, Mustafa Ozgur Bilecik Seyh Edebali Univ Dept Civil Engn TR-11210 Bilecik Turkey

In this reported work, the free axial vibration response of carbon nanotubes (cNTs) with arbitrary boundary conditions is studied based on the non-local elasticity theory. Using Fourier sine series together with Stokes'transformation, the general frequency determinant of cNTs is obtained. The main advantage of this method is its capability of dealing with rigid or restrained boundary conditions. comparisons between the results of the presented method and previous works in the literature have been performed. Good agreement is obtained when enough terms are included in the Fourier series expansion. The effects of spring parameters on the vibration frequencies are discussed in detail. The proposed analytical method can be utilised for dynamic analyses of nanorods (cNTs) with arbitrary boundary conditions.

关键词： vibrations carbon nanotubes elasticity Fourier series carbon nanotubes free axial vibration response arbitrary boundary conditions nonlocal elasticity theory Fourier sine series Stokes transformation general frequency determinant rigid boundary conditions Fourier series expansion spring parameters vibration frequencies dynamic analyses nanorods restrained boundary conditions c

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Highly compression-tolerant folded carbon nanotube/paper as solid-state supercapacitor electrode

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MIcRO & NANO LETTERS 2016年第10期11卷 586-590页

作者： Song, Yu cheng, Xiaoliang chen, Haotian Han, Mengdi chen, Xuexian Huang, Jiahuan Su, Zongming Zhang, Haixia Peking Univ Inst Microelect Natl Key Lab Sci & Technol Micro Nano Fabricat Beijing 100871 Peoples R China Peking Univ Acad Adv Interdisciplinary Studies Beijing 100871 Peoples R China

An original highly compression-tolerant folded carbon nanotube (cNT)/paper electrode, which could be assembled into compressible solid-state supercapacitor with polyvinyl alcohol/phosphoric acid gel electrolyte, is designed. It is worth mentioning that both the compression-tolerant ability of the folded structure and the strain ability of the cNT electrode are conducive to achieving the compressible supercapacitor. Such device could withstand pressure and shape-changing, which has great potential to be used in various environments. This compressible solid-state supercapacitor also owns the maximum specific capacitance of 11.07 mF/cm(2), and capacitance retention retains more than 90% after 100 cycling times. Furthermore, the stability performance of the device is also discussed which is almost steady under 50% strain state. When two devices are connected in serial and fully charged, this power unit could light up a red light emitting diode continuously even under the compression state. Therefore, this device performs as a promising candidate to be compatible with other compression-tolerant electronics and enlightens a broad field of compressible energy storage and self-powered systems.

关键词： carbon nanotubes supercapacitors electrochemical electrodes electrolytes capacitance highly compression-tolerant folded carbon nanotube-paper solid-state supercapacitor electrode compressible solid-state supercapacitor polyvinyl alcohol-phosphoric acid gel electrolyte strain ability maximum specific capacitance capacitance retention stability performance power unit red light emitting diode compression-tolerant electronics compressible energy storage self-powered systems c

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Analysis of nonlinear dynamic stability of single-walled carbon nanotubes in thermal environments

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MIcRO & NANO LETTERS 2014年第3期9卷 175-179页

作者： Fu, Yiming Zhong, Jun Hunan Univ Coll Mech & Vehicle Engn Changsha 410082 Hunan Peoples R China

Based on the non-local Euler beam theory, the nonlinear dynamic stability of single-walled carbon nanotubes (SWcNTs) embedded in an elastic medium including the thermal effects is presented. The nonlinear dynamic equations and the boundary conditions of the SWcNTs are obtained by using the Hamilton variation principle. By adopting the Galerkin procedure, the governing nonlinear partial differential equation is converted into a nonlinear ordinary differential equation, and then the incremental harmonic balance method is applied to obtain the principal unstable regions of the SWcNTs. In the numerical examples, the effects of the thermal loads, the non-local parameters and the elastic medium on the nonlinear dynamic stability, respectively, are discussed.

关键词： carbon nanotubes elasticity Galerkin method partial differential equations nonlinear dynamic stability single-walled carbon nanotubes thermal environments nonlocal Euler beam theory embedded SWcNT elastic medium nonlinear dynamic equations boundary conditions Hamilton variation principle Galerkin procedure governing nonlinear partial differential equation nonlinear ordinary differential equation incremental harmonic balance method principal unstable regions thermal loads nonlocal parameters c

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Low-frequency noise and hysteresis in graphene field-effect transistors on oxide

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MIcRO & NANO LETTERS 2010年第1期5卷 37-41页

作者： Imam, S. A. Sabri, S. Szkopek, T. McGill Univ Montreal PQ H3A 2A7 Canada

The authors report measurements of low-frequency noise and hysteresis in graphene monolayer and bilayer field-effect transistors (FETs) fabricated on 90 and 290 nm oxidised silicon substrates. The authors observe hysteresis induced by stressing the oxide up to fields of 2 MV/cm and have characterised the hysteresis against stress time and sample temperature. Low-frequency current noise with a 1/f(2) spectral density arises from the drift of neutrality point voltage, and subsequent drift of graphene FET channel current. A simple model of charge trapping at the graphene-oxide interface and thermally activated ion motion accounts for the temperature dependence of the observed hysteresis.

关键词： nanoelectronics channel current neutrality point voltage graphene monolayer c thermally activated ion motion field effect transistors stress time oxidised silicon substrates charge trapping Fullerene, nanotube and related devices low-frequency current noise size 290 nm size 90 nm monolayers FET graphene 1-f 2 spectral density hysteresis field-effect transistors graphene bilayer

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Field emission of self-assembled carbon nanotubes on triode structure

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ELEcTRONIcS LETTERS 2002年第12期38卷 602-603页

作者： Lee, JH Heo, JN Yi, WK Yu, SG Jeong, TW Lee, cS Han, IT Kim, HJ Yoo, JB Kim, JM Samsung Adv Inst Technol Display Lab Suwon 440600 South Korea Samsung Adv Inst Technol Natl Creat Res Initiat Ctr Electron Emiss Source Suwon 440600 South Korea Sungkyunkwan Univ Ctr Nanotubes & Nanostructured Composites Jangan Gu Suwon 440746 South Korea

A triode structure of field emission display was prepared by self-assembly of thiol-treated carbon nanotubes on a cathode plate of the device. The self-assembly process was easily carried out by overnight immersion of the triode structure in the thiol-treated carbon nanotube solution. The current-voltage measurement exhibited triode-type field emission characteristics depending on the gate voltage modulation.

关键词： carbon nanotube thiol-treated solution field emission displays triodes field emission display carbon nanotubes triode structure self-assembly c Vacuum microelectronics Display materials current-voltage characteristics Fullerene, nanotube and related devices

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cONTRIBUTION OF NIcOTINIc AND MUScARINIc REcEPTORS IN THE SEcRETION OF cATEcHOLAMINES EVOKED BY ENDOGENOUS AND EXOGENOUS AcETYLcHOLINE

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NEUROScIENcE 1983年第3期10卷 973-978页

作者： WAKADE, AR WAKADE, TD Department of Pharmacology State University of New York Downstate Medical Center 450 Clarkson Avenue Brooklyn NY 11203 U.S.A.

The functional contribution of nicotinic and muscarinic receptors of the rat adrenal medullary cells to the secretion of catecholamines evoked by exogenous and endogenous acetylcholine [Ach] was evaluated. The ratio of epinephrine to norepinephrine in the perfusate of the adrenal gland stimulated with various agents was compared to that in the adrenal medulla. The effect of tetrodotoxin on the secretion of catecholamine evoked by nicotine and muscarine was studied. Nicotine and muscarine agonists, and hexamethonium and atropine antagonists, showed that the adrenal gland of the rat contains nicotinic and muscarinic receptors, and that both are linked to the secretion of catecholamines. These receptors were activated in a different manner by endogenous and exogenous Ach. Secretion evoked by injected Ach was barely blocked by either hexamethonium or atropine, but their combination produced a block. Secretion evoked by endogenous Ach (splanchnic nerve stimulation) was largely reduced (75%) by hexamethonium alone. The ratios of epinephrine to norepinephrine in the perfusate were comparable before and after stimulation of the adrenal gland with nicotine, Ach, or K+;the ratio was slightly higher for muscarine. Tetrodotoxin blocked the nicotine-evoked secretion by .apprx. 75% but had very little effect on the secretion evoked by muscarine. Nicotinic receptors were primarily concentrated in the synaptic zones and were involved in the physiological stimulation of the adrenal medulla, whereas extrasynaptic regions contained a mixture of nicotinic and muscarinic receptors, activated by injected Ach. The tetrodotoxin experiments indicated that physiologically released Ach generated action potentials through synaptic nicotinic receptors to initiate increase in ca influx and subsequent secretion of catecholamines.

关键词： Ach acetylcholine cA catecholamines c 6 hexamethonium TTX tetrodotoxin

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cYTOcHROMES FUNcTIONALLY ASSOcIATED TO PHOTOcHEMIcAL-REAcTION cENTERS IN RHODOPSEUDOMONAS-PALUSTRIS AND RHODOPSEUDOMONAS-AcIDOPHILA

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BIOcHIMIcA ET BIOPHYSIcA AcTA 1986年第1期852卷 9-18页

作者： MATSUURA, K SHIMADA, K Department of Biology Faculty of Science Tokyo Metropolitan University Fukazawa 2-1-1 Setagaya-ku Tokyo 158 Japan

Electron donors to photo-oxidized reaction centers were studied in Rhodopseudomonas palustris and R. acidophila using whole cells, membrane preparations and reaction center-B880 complexes. In Rps. palustris, no hemes were tightly bound to the reaction center complex and cytochrome c2 was presumed to be the direct electron donor to the photo-oxidized bacteriochlorophyll dimer in whole cells. cytochrome c2 was lost in the membrane preparation obtained after a French press disruption of cells and mammalian cytochrome c added externally was oxidized by illumination. On the other hand, in Rps. acidophila, the reaction center complex was tightly associated with four cytochrome hemes, two of which were identified as cytochrome c-553 (Em7 = 110 mV) and the other two as cytochrome c-555 (Em7 = 110 mV) and the other two as cytochrome c-555 (Em7 = 360 mV). When both cytochromes were reduced prior to illumination, cytochrome c-553 was rapidly oxidized by a flash. cytochrome c-555 was the one oxidized by a flash when cytochrome c-553 was already oxidized before activation. cytochrome c2 was presumed to be the electron donor to the photo-oxidized cytochrome c-555 in whole cells. In the membrane preparation, a rapid electron transfer was observed from externally added mammalian cytochrome c to photooxidized cytochrome c-555. A possible phylogenetic correlation between the absence of the tightly bound cytochromes and a long class of cytochrome c2 (Dickerson, R.E. (1980) Nature 283, 210-212) is discussed.

关键词： Bacterial photosynthesis Electron transfer cytochrome c Reaction center ( Rps. palustris, Rps. acidophila ) Bchl bacteriochlorophyll (Bchl) + 2 oxidized bacteriochlorophyll dimer in reaction centers B-880 light-harvesting pigment-protein complex with an absorption peak of bacteriochlorophyll around 880 nm Rc reaction center Q A primary quinone acceptor of reaction centers cccP carbonyl cyanide m -chlorophenylhydrazone DAD 2,3,5,6-tetramethyl- p -phenylenediamine HNQ 2-hydroxynaphthoquinone PMS N -methylphenazonium methosulfate Mops 4-morpholinepropanesulfonic acid

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cHANGES IN INTRAcELLULAR PH IN FRENcH-BEAN NODULES INDUcED BY SENEScENcE AND NITRATE TREATMENT

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PLANT ScIENcE 1988年第2期56卷 99-106页

作者： PLADYS, D BARTHE, P RIGAUD, J Laboratoire de Biologie Végétale UA CNRS 1114 Faculté des Sciences et des Techniques 06034 Nice Cedex France

Intracellular pH of Phaseolus nodules was determined by using radioactive 5,5-dimethyloxazolidine-2,4-dione (DMO) as a probe. A continuous decline in the intracellular pH was observed when nodule age increased. The extracellular volume of nodules, required for the pH calculation, was the lowest in mature nodules and increased in senescing nodules. Low concentrations of nitrate in the culture medium induced a drop in nitrogen fixation associated with a decrease in the intracellular pH. Acidic proteolysis measured by in vitro hydrolysis of leghemoglobin was strongly stimulated under these conditions. In Phaseolus nodules, senescence and nitrate treatment were similarly characterized by a lower intracellular pH and an active proteolysis which both contributed to a decline in nitrogen fixation capacities.

关键词： c 2 H 2 reduction intracellular pH nitrate proteolysis root nodule senescence c i intracellular concentration c e extracellular concentration DMO, 5,5-dimethyloxazolidine-2,4-dione pH e extracellular pH pH i intracellular pH

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