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Orbiting nanosectors inside carbon nanotori

MIcRO & NANO LETTERS 2007年第3期2卷 50-53页

作者： Hilder, T. A. Hill, J. M. Univ Wollongong Sch Math & Stat Nanomech Grp Wollongong NSW 2522 Australia

The notion of nanotransport or nanomotion is presently a theoretical concept only, in that no one has actually observed the phenomena in an experimental context. For example, the oscillatory motion of one carbon nanotube sliding inside another is predicted on the basis of molecular dynamics studies, and the authors have provided some elementary modelling of the phenonmena. More recently, the authors have modelled a c-60 fullerene orbiting inside a nanotori. The related problem of a carbon nanotorus-nanosector oscillator or orbiter is examined, in which a small sector of a nanotorus orbits inside a second seamless nanotorus of larger radius. Using elementary mechanical principles and applied mathematical modelling techniques, we determine the equilibrium configuration for a number of carbon nanotorus-nanosector oscillators and subsequently investigate their operating frequencies. In line with carbon nanotube oscillators, the proposed analysis predicts orbiting frequencies in the gigahertz range.

关键词： nanotransport oscillations c Modelling and computer simulation of solid structure carbon nanotubes carbon nanotori fullerenes nanomotion molecular dynamics carbon nanotube molecular dynamics method oscillatory motion nanosectors Structure of fullerenes and fullerene-related materials fullerene

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Influence of total gas flow on carbon nanotube forests synthesised by water-assisted chemical vapour deposition

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MIcRO & NANO LETTERS 2013年第11期8卷 779-782页

作者： Liang, Youxuan Jiang, chuan Zhao, Bin Yang, Junhe Shanghai Univ Sci & Technol Sch Mat Sci & Engn Shanghai 200093 Peoples R China Shanghai Univ Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China

The influence of total gas flow on the growth of carbon nanotube (cNT) forests in water-assisted chemical vapour deposition has been investigated. It was found that the average height of the cNT forests decreased gradually from 996.53 to 696.8 m, and the growth yield decreased notably from 2.91 to 1.98 mg/cm(2) as the total flow increased, but the crystallinity and thermostability of cNT forests increased with increasing total flow. Investigation on cNT growth kinetics suggested that increasing the total flow could decrease the growth rate and shorten catalyst lifetime because of decreased gas dwell time and enhanced subsurface diffusion of Fe catalyst.

关键词： carbon nanotubes catalysts chemical vapour deposition iron nanofabrication surface diffusion thermal stability total gas flow Fe c subsurface diffusion gas dwell time catalyst lifetime growth kinetics thermostability crystallinity growth yield average height water-assisted chemical vapour deposition carbon nanotube forests

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Gate dielectric material dependence of current-voltage characteristics of ballistic Schottky barrier graphene nanoribbon field-effect transistor and carbon nanotube field-effect transistor for different channel lengths

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Micro & Nano Letters 2015年第10期10卷 523-527页

作者： Ahmed, Sheikh Shawkat, Mashiyat chowdhury, Md. Iramul Mominuzzaman, Sharif BRAC Univ Dept Elect & Elect Engn Dhaka 1212 Bangladesh Bangladesh Univ Engn & Technol Dept Elect & Elect Engn Dhaka 1000 Bangladesh

currently, the advancement of silicon transistor technology is being hindered by different issues such as scaling limits. It has become imperative to replace existing silicon technology with new technology to continue the scaling of MOSFETs. Thus, new materials and new production techniques are being studied laboriously to continue the trend set by Moore's Law. The graphene nanoribbon (GNR) and the carbon nanotube (cNT) are two such promising materials that can replace silicon in future MOSFETs. A study has been conducted of the effect of the relative dielectric constant on the device performances of a ballistic Schottky barrier GNR field-effect transistor (GNRFET) and a cNT field-effect transistor (cNTFET) for two different channel lengths and a comparative analysis between the two transistors is provided. When a gate material with a high relative dielectric constant is used in FETs, it has been observed that both the transistors show higher on-state drain currents for the different channel lengths. Moreover, the on and off-state current ratios and transconductance for the GNRFET and the cNTFET are calculated and plotted for further differentiation between the performances of the GNRFET and the cNTFET.

关键词： ballistic transport nanoribbons graphene graphene devices carbon nanotube field effect transistors carbon nanotubes nanoelectronics Schottky barriers Schottky gate field effect transistors permittivity electrical conductivity gate dielectric material dependence current-voltage characteristics ballistic Schottky barrier graphene nanoribbon field-effect transistor carbon nanotube field-effect transistor channel lengths Moore law dielectric constant on-state drain currents off-state current ratios transconductance c

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Molecular motion, morphology and properties of 3-isocyanato-propyltriethoxysilane-modified multi-walled carbon nanotube/epoxy composites

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MIcRO & NANO LETTERS 2011年第6期6卷 463-467页

作者： Wu, Sheng-Yen Yuen, Siu-Ming Ma, chen-chi M. Huang, Yuan-Li Teng, chih-chun Natl Tsing Hua Univ Dept Chem Engn Hsinchu 30043 Taiwan

In this study, both epoxy resin and multi-wall carbon nanotubes (MWcNTs) were modified with 3-isocyanato-propyltriethoxysilane (IPTES). Scanning electron microscopy and transmission electron microscopy microphotographs show that the MWcNTs dispersed well in the epoxy matrix. The molecular motion of silane-modified MWcNT/epoxy composites was studied using high-resolution solid-state (13)c NMR. Results show that 1 wt% silane-modified MWcNT/epoxy composite exhibits less molecular motion than composite with a lower silane-modified MWcNT content. The glass transition temperature (T(g)) of the neat epoxy is 192.6 degrees c and increases to 212.5 degrees c with 1 wt% IPTES-MWcNT content. Dynamic mechanical analysis data of the MWcNT/epoxy composites show the storage modulus at 50 degrees c and the T(g) of the IPTES-modified epoxy increased with IPTES-MWcNT content.

关键词： resins nanocomposites high-resolution solid-state 13c NMR Elasticity, elastic constants storage modulus Structure of solid clusters, nanoparticles, nanotubes and nanostructured materials c transmission electron microscopy elastic moduli scanning electron microscopy Nuclear magnetic resonance and relaxation (condensed matter) Glass transitions molecular motion glass transition temperature Elasticity and anelasticity dynamic mechanical analysis nuclear magnetic resonance carbon nanotubes glass transition 3-isocyanato-propyltriethoxysilane-modified multi-walled carbon nanotube-epoxy composites temperature 50 degc Methods of nanofabrication and processing

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cONFORMATION OF INSULIN AND ITS FRAGMENTS IN SURFAcTANT SOLUTIONS

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BIOcHIMIcA ET BIOPHYSIcA AcTA 1981年第2期667卷 285-293页

作者： WU, cSc YANG, JT UNIV CALIF SAN FRANCISCO CARDIOVASC RES INSTSAN FRANCISCOCA 94143 UNIV CALIF SAN FRANCISCO DEPT BIOCHEM & BIOPHYSSAN FRANCISCOCA 94143

The conformation of insulin, A and B chains and des(B23–30)octapeptide insulin (DOI) in surfactant solutions was studied by circular dichroism (cD). Addition of sodium dodecyl sulfate (NaDodSO 4 ), dodecylammonium chloride (DodNH 3 cl) or dodecyltrimethylammonium chloride (Dod(cH 3 ) 3 Ncl) slightly alters the cD spectrum of insulin, but not DOI. The cD of insulin in NaDodSO 4 solution resembles that of DOI without the surfactant, suggesting the dissociation of the cOOH-terminal antiparallel β-form of insulin oligomers (DOI lacks B23–30 and exists as monomers). Reduced insulin and DOI lose their ordered structure in water, but their helical conformation is restored in surfactant solutions. Reduced DOI in NaDodSO 4 solution appears to be more helical than DOI with the disulfide bonds intact as judged from their ellipti cities. Oxidized A and B chains of insulin are unordered in aqueous solution. A chain that lacks cationic side groups remains unordered in a NaDodSO 4 solution. It shows a small amount of helix in a Dod(cH 3 ) 3 Ncl solution and forms the interchain β-form in a DodNH 3 cl solution. In contrast, B chain becomes partially helical in all three surfactant solutions.

关键词： Insulin conformation Des(B23–30)octapeptide insulin Somatostatin Surfactant circular dichroism DOI, des(B23–30)octapeptide insulin NaDodSO 4 , sodium dodecyl sulfate (usually abbreviated as SDS) DodNH 3 cl, dodecylammonium chloride Dod(cH 3 ) 3 Ncl, dodecyltrimethylammonium chloride c 12 E 7 , dodecylheptaoxyethylene ether cD, circular dichroism

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contribution of cmeG to antibiotic and oxidative stress resistance in campylobacter jejuni

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JOURNAL OF ANTIMIcROBIAL cHEMOTHERAPY 2011年第1期66卷 79-85页

作者： Jeon, Byeonghwa Wang, Yang Hao, Haihong Barton, Yi-Wen Zhang, Qijing Iowa State Univ Dept Vet Microbiol & Prevent Med Coll Vet Med Ames IA 50011 USA China Agr Univ Dept Pharmacol & Toxicol Coll Vet Med Beijing 100094 Peoples R China Huazhong Agr Univ Natl Reference Lab Vet Drug Residues HZAU MOA Key Lab Food Safety Evaluat Wuhan Peoples R China

campylobacter jejuni is a leading foodborne pathogen worldwide and its resistance to antimicrobials is a major concern for public health. The cmeG (cj1375) gene in c. jejuni encodes a putative efflux transporter of the major facilitator family, but its function in antimicrobial resistance has not been determined. This study aimed to characterize the function of cmeG in conferring resistance to antibiotics and oxidative stress. The cmeG gene (cj1375) in c. jejuni was inactivated by insertional mutagenesis and overexpressed by cloning with a shuttle vector. These constructs were compared with the wild-type strain using antimicrobial susceptibility tests and drug accumulation assays. The cmeG mutation reduced bacterial growth and rendered c. jejuni more susceptible to ciprofloxacin, erythromycin, gentamicin, tetracycline, rifampicin, ethidium bromide and cholic acid as well as hydrogen peroxide, and in trans complementation restored the susceptibility to near wild-type level. RT-PcR showed that cmeG is co-transcribed with its downstream gene cmeH (cj1376) encoding a putative periplasmic protein, but mutation of cmeH alone did not affect the susceptibility to antibiotics. Notably, overexpression of the cmeGH operon in c. jejuni NcTc 11168 significantly increased its resistance to fluoroquinolones. In addition, the cmeG mutant accumulated more EtBr and ciprofloxacin than the wild-type strain. These results indicate that cmeG functions as a multidrug efflux transporter contributing to antibiotic resistance and oxidative defence in campylobacter.

关键词： antibiotic resistance efflux pumps c jejuni

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Gain characteristics of 6cm-long Er-doped bismuthate waveguide

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ELEcTRONIcS LETTERS 2005年第6期41卷 317-318页

作者： Kondo, Y Ono, M Kageyama, J Hayashi, H Reyes, M Sugimoto, N Asahi Glass Co Ltd Res Ctr Kanagawa Ku Yokohama Kanagawa 2218755 Japan

Er-doped muliticomponent bismuthate channel waveguides have been fabricated. Dependence of emission lifetime of Er3+ ions on the concentration of Er3+ ions is investigated and compared with the other silicate material... 详细信息

关键词： erbium optical communication equipment optical waveguides solid lasers waveguide lasers wavelength division multiplexing Er-doped bismuthate waveguide Er-doped multicomponent bismuthate channel waveguides Er-doped planar waveguide amplifier WDM network c Erbium Optical communication equipment Optical waveguides channel waveguide gain characteristic waveguide lasers solid state lasers wavelength division multiplexing network Silicate materials Wavelength division multiplexing

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Inhibitory effects of caffeine on gustatory plasticity in the nematode caenorhabditis elegans

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BIOScIENcE BIOTEcHNOLOGY AND BIOcHEMISTRY 2016年第10期80卷 1990-1994页

作者： Urushihata, Takuya Takuwa, Hiroyuki Higuchi, Yukako Sakata, Kazumi Wakabayashi, Tokumitsu Nishino, Asuka Matsuura, Tetsuya Iwate Univ United Grad Sch Agr Sci Div Thermobiosyst Relat Morioka Iwate Japan Natl Inst Radiol Sci Dept Biophys Mol Imaging Ctr Chiba Japan Iwate Univ Dept Chem & Biosci Fac Engn Morioka Iwate Japan

The effects of caffeine on salt chemotaxis learning were investigated using the nematode caenorhabditis elegans. To estimate the degree of salt chemotaxis learning, nematodes were placed in a mixed solution of Nacl and caffeine, and then the chemotaxis index of Nacl was obtained from the nematodes placed on agar medium after pre-exposure to caffeine concentrations of 0.01, 0.1, 0.3, and 1.0%. Locomotor activity and preference behavior for caffeine were also estimated under these caffeine conditions. Nematodes pre-exposed to 0.3% caffeine showed inhibition of salt chemotaxis learning. Additional experiments indicated that nematodes showed a preference response to the middle concentration of caffeine (0.1%), with preference behavior declining in the 0.3% caffeine condition. Stable locomotor activity was observed under 0.01-0.3% caffeine conditions. These results suggest that salt chemotaxis learning with 0.3% caffeine is useful for investigating the effects of caffeine on learning in nematodes.

关键词： c elegans learning function caffeine chemotaxis

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Growth of nanocarbons by catalysis and their applications

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MRS BULLETIN 2017年第11期42卷 790-793页

作者： Thrower, Peter A. cheng, Hui-Ming Penn State Univ Dept Mat Sci & Engn University Pk PA 16802 USA Chinese Acad Sci Inst Met Res Shenyang Natl Lab Mat Sci Beijing Peoples R China Tsinghua Univ Tsinghua Berkeley Shenzhen Inst Beijing Peoples R China

Nanocarbons, such as carbon nanotubes and graphene, have had a remarkable history and impact on current applications. We briefly review the genesis and development of nanocarbons over the last 50 years, referencing key articles, including the role of catalysts in their formation. This issue focuses on the formation mechanisms and controlled growth of carbon nanotubes and graphene on substrates through catalytic processes. The five contributions in this issue review the mechanisms and theory of catalytic growth of nanocarbons (carbon nanotube forests, superaligned arrays, single-wall carbon nanotubes), the growth of large-quantity, high-quality graphene on metal substrates, and the unique and excellent properties for current and potential commercial applications.

关键词： c catalytic nanoscale

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Microstructures of carbon nanofilaments growing on graphite nanosheets

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MIcRO & NANO LETTERS 2010年第6期5卷 386-388页

作者： Lu, H. F. Kuo, W. S. Feng Chia Univ Dept Aerosp & Syst Engn Taichung 407 Taiwan

This study examines microstructures of a special three-dimensional nanocarbon composed of carbon nanotubes (cNTs) and graphite nanosheets (GNSs). The GNSs were made by exfoliating natural graphite flakes, and cNTs were grown on the GNSs by chemical vapour deposition. Nickel nanoparticles were deposited on the GNSs and employed as the catalyst for cNT growth. The micrographs show that initial deposition of carbon atoms results in structures different from the hollow, multi-walled cNTs. This initial portion forms the root of the cNT and becomes the link between the GNS and the cNT. The root is a form of carbon nanofibres (cNFs) with relatively random graphitic structures. After the cNF, cNT and amorphous carbon are followed. The focus here is how the graphitic structure changes from a disordered cNF to a regularly multi-walled cNT.

关键词： Low-dimensional structures: growth, structure and nonelectronic properties nickel nanoparticles constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder catalysis amorphous carbon 3D carbon nanofilaments microstructure catalyst Structure of solid clusters, nanoparticles, nanotubes and nanostructured materials Solid-solid transitions c graphite nanofibres graphite nanosheets chemical vapour deposition structural transformation Heterogeneous catalysis at surfaces and other surface reactions micrographs Microstructure carbon nanofibers exfoliation Structure of fullerenes and fullerene-related materials natural graphite flakes chemical vapour deposition multiwalled carbon nanotubes Preparation of fullerenes and fullerene-related materials, intercalation compounds, and diamond carbon nanotubes solid-state phase transformations nanofabrication Methods of nanofabrication and processing

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