bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cellular Response to Nanoparticles
Authors: Shortkroff Sonya , Turell Mary Beth , Rice Karen , Thornhill Thomas S. 
Published: April 2011

AbstractParticles of BaSO4 with sizes in nano-scale and micro-scale ranges were investigated for their interactions with fibroblasts in order to determine the biocompatibility of nano-sized particles. Cells were incubated in the presence of particles at 1, 10 and 100 times the particle to cell surface area ratio and at a single concentration of 0.138 mg/ml. Production by the fibroblasts of an inflammatory cytokine in response to the particles was measured and the effect of particle size and volume on cell viability was examined. All particles were cell associated and some agglomeration was visible at all size ranges. Release of interleukin-6 by cells subjected to the same concentration of Ba SO4was similar to control levels, while addition of 1x surface area ratio (SAR) of particles to cells resulted in an increase in IL-6 from 94 pg/ml for 100 nm particles to 218 pg/ml with 2 μm particle diameter. By increasing particle to cell surface area ratios from 1× to 100x, cell viability was compromised for the 2μm particles but was not affected by the nanometer sized BaSO4 particles.
Application of Dispersed Nano Particles
Authors: Oda Masaaki , Abe Tomoyuki , Suzuki Toshihiro , Saito Norimich , Iwashige Hisashi , Kutluk Ghalip 
Published: April 2011

AbstractNano-particles can become one of the best materials for forming thin and fine pitch films at low temperature, if particles are individually dispersed densely in a solvent. Individually dispersed metal(gold, silver, copper) nano-particle(d-nano particle) are formed at a state of suspension in an organic solvent by the modified gas evaporation method where formed particles are covered with an organic surfactant just after their formation. The particle formed by the gas evaporation method are metal impurity free and have a narrow size distribution. This suspension is condensed and used as a formed of solution or paste. D-nano particle solution or paste can be baked at 200-300C to form metal thin films. These has been applied to PDP electrode repairing, coloring of car window glass, a filler of electric conductive resin paste and ULSI interconnection formation.
Effect of Particle Size on the Luminescent Properties of Europium Doped Yttrium Oxide Nano-Phosphors
Authors: Copeland Thomas S. , Lee Burtrand I. , Elrod Amanda K. 
Published: April 2011

AbstractRed light emitting Eu3+ doped Y2O3 phosphor nano-particles were synthesized by a solgel method combined with a furnace firing. The particle size, measured using dynamic light scattering (DLS), was between36nm and 1 micron depending on the conditions. Final dopant concentrations were measured through inductively coupled plasma (ICP). The ICP results show a dopant loss of 58% during the processing for the europium doped yttria. Red photoluminescence (PL) and cathodoluminescence (CL), at 614nm was observed from the phosphor particles under UV excitation and electron bombardment. Results show that the samples with a mean diameter of 30nm displayed a significant increase in PL brightness over the samples whose mean diameter was 215nm. The lag in PL, and CL intensity behind the commercial reference samples is attributed to the significantly lower dopant levels present in the experimental phosphors. Results also indicate that these processing methods and nanophosphors may be a useful alternative to current materials and methods.
In-situ Gold Coating of Superparamagnetic Nanoparticles by Microemulsion Method
Authors: Kim D. K. , Mikhailova M. , Toprak M. , Zhang Y. , Bjelke B. , Kehr J. , Muhammed M. 
Published: April 2011

AbstractMonodispersed gold coated Superparamagnetic Iron Oxide Nanoparticles (SPION) were prepared in water-in-oil reverse microemulsion (μE) of CTAB (cetyltrimethyl -ammonium bromide)/octane/butanol/water and Brij@97/cyclohexane/water. Gold coated SPION were obtained in the μE system by coprecipitation of magnetite and subsequent reduction of Au on the surface of the magnetite using NaBH4. The SPION were characterized by TEM with EDX, AFM, TGA, ESA, UV-Vis spectroscopy, and SQUID at intermediate and final stages.
Synthesis and ROMP of Metal Nanocluster Containing Norbornene Derivatives
Authors: Wynne James H. , Lloyd Christopher T. , Bullock Steven E. , Cozzens Robert F. 
Published: April 2011

AbstractWe report the synthesis of a series of highly functional metal chelated silyl- and tert-butyl-protected 2, 3-diaminomethyl norbornene derivatives. Subsequent alterations to the previously synthesized norbornene adducts afford many other derivatives containing such functionalities as alkyl, cyano, esters, and ethers. These derivatives are then subjected to ring-opening metathesis polymerization (ROMP) employing a ruthenium homogeneous catalyst to afford phase separated block polymers. The block polymers formed serve as unique templates for the formation of size controlled metal nanoclusters having a narrow dispersion. These metal nanoclusters containing diblock polymers are evaluated as unique electrical and optical materials.
Electrical Characterization of Nanostructured Carbon Films Produced by Supersonic Cluster Beam Deposition
Authors: Piseri Paolo , Barborini Emanuele , Bruzzi Mara , Miglio Stefania , Bongiorno Gero , Milani Paolo 
Published: April 2011

AbstractElectrical conduction in nanostructured carbon (ns-C) films produced by deposition of a supersonic beam of neutral carbon clusters has been studied. The d.c. conduction properties of these films have been measured in-situ during the deposition process and ex-situ as a function of the temperature in vacuum and in ambient of different gases (H2, N2, CH4, He). The ns-C films exhibit an ohmic behavior with a room temperature resistivity in the range 10MΩcm-1GΩcm depending on the growth and storage conditions. Conductivity vs. temperature measured in vacuum in the range 300-400K is characterized by activation energies in the range 0.3-0.7eV, the current response does not differ significantly in gas atmosphere.
Structural and Spectroscopic Study of Manganese Silicide Islands on Silicon
Authors: Tanaka Miyoko , Zhang Qi , Takeguchi Masaki , Furuya Kazuo 
Published: April 2011

AbstractThe Mn deposited clean Si (111) substrates were examined with UHV-TEM and STM that are part of an UHV-TEM/STM integrated characterization system. The Mn deposition with coverages of 5-20 ML followed by annealing at 673 K formed MnSi islands with Moire fringes. They showed metallic character. Subsequent annealing at 873 K dissipated the islands instead of transforming them into MnSi1.7. The re-deposition of Mn and re-annealing at 473 K succeeded to transform MnSi islands into MnSi1.7. The islands had several orientation relationships with substrate Si, and were semiconducting. The growth mechanism of MnSi1.7 is inferred.
Micropatterned Vertically Aligned Carbon Nanotube Growth on a Si Surface or inside Trenches for field-emission devices
Authors: Sohn Jung Inn , Lee Seonghoon , Song Yoon-Ho , Choi Sung-Yool , Lee Jin Ho , Kang Young-Il 
Published: April 2011

AbstractThe good field-emission properties of carbon nanotubes coupled with their high mechanical strength, chemical stability, and high aspect ratio, make them ideal candidates for the construction of efficient and inexpensive field-emission electronic devices. The fabrication process reported here has considerable potential for use in the development of integrated radio frequency amplifiers or field emission-controllable cold electron guns for field emission displays. This fabrication process is compatible with currently used semiconductor processing technologies. Micropatterned vertically aligned carbon nanotubes were grown on planar Si surface or inside the trenches, using chemical vapor deposition, photolithography, pulsed-laser deposition, reactive ion etching, and the lift-off method. To control the field-emission current by a 3rd electrode, the gate electrode, we grew carbon nanotubes inside the trenches. This triode-type structure is the best to realize the gray-scale carbon nanotube field emission. This carbon nanotube fabrication process can be widely applied for the development of electronic devices using carbon nanotube field emitters as cold cathodes and could revolutionize the area of field-emitting electronic devices such as RF amplifiers and field emission displays.
Structure of Frilled Carbon Nanowires Synthesized by Sulfur-assisted Chemical Vapor Deposition
Authors: Mitsui Tadashi , Sekiguchi Takashi , Nishitani-Gamo Mikka , Zhang Yafei , Ando Toshihiro 
Published: April 2011

AbstractEffects of hydrogen sulfide on the structure of carbon nanotubes (CNTs) were studied using high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS). The CNTs were synthesized with an iron thin-film catalyst by microwave plasma-assisted CVD on the diamond substrate. The HRTEM images revealed that essentially all of the CNTs obtained in this study were multiwall (MWCNT). The addition of H2S resulted in nanotubes with split skins as cornhusks and/or frills. Electron energy loss spectra of the cornhusks indicated that they consist of sp2, sp3 and amorphous carbon phase. The spectra revealed that the sp3 to sp2 ratio at the points where cornhusks divide from the main stem was more than that at the edge of the cornhusks. No evidence of sulfur incorporation into the MWCNTs grown with the H2S addition was found. We speculate that the chemical nature of sulfur on the CNT growth yields such anomalous structure.
Controlling the Aligned Growth of Carbon Nanotubes by Substrate Selection and Patterning
Authors: Jung Y. , Wei B. Q. , Vajtai R. , Ward J. , Zhang R. , Ramanath G. , Ajayan P. M. 
Published: April 2011

AbstractTo build nanotube based nanodevices, controlling the growth of aligned carbon nanotubes will be essential. Our group reported a method for growing aligned nanotube selectively on SiO2 surfaces by thermal chemical vapor deposition (CVD) method from xylene-metallocene mixtures. Here we will describe further studies on the roles of shape and thickness of patterned oxide structures for the controlled growth of aligned carbon nanotubes. By designing the shapes and the thickness of silicon oxide patterns with conventional micro fabrication techniques like lithography and dry & wet etching we could control the growth position as well as orientation of aligned carbon nanotubes precisely.
Dependence of the Second-order G'-band Profile on the Electronic Structure of Single-wal Nanotubes
Authors: Filho A. G. Souza , Joribo A. , Dresselhaus G. , Dresselhaus M. S. , Swan A. K. , Ünlü M. S. , Goldberg B. B. , Hafner J. H. , Lieber C. M. , Pimenta M. A. , Saito R. 
Published: April 2011

AbstractWe analyze the dependence of the second-order G'-band profile in terms of their (n,m) indices by measuring the resonance Raman spectra of several semiconducting and metalic isolated single wal carbon nanotubes. We show that this profile is very sensitive to the electronic structure, thus making it possible to get structural (n,m) information and to probe the splitting of the van Hove singularities in the electronic density of states due to the trigona warping effect.
Injection of Polarized Spins and Anti-Localization Caused by Slight Doping of Heavy Impurities into One End of Carbon Nanotubes
Authors: Haruyama Junji , Takesue Izumi , Hasegawa Tetsuro 
Published: April 2011

AbstractElectrode atoms are slightly diffused, with only about 5% volume-ratio, into the top end of multi-walled carbon nanotubes (MWNTs), standing in nano-pores of porous Alumina membranes. Diffusion of light-mass materials (carbon and aluminum) leads to weak localization in the Altshuler-Aronov-Spivak (AAS) oscillations, which is qualitatively consistent with previous works on MWNTs. In contrast, we find that diffusion of heavy materials (gold and platinum) changes this weak localization into an anti-localization in the MWNT bulk. This effect is only observable when electrons are injected through the diffusion region, and undergo a φ-phase shift in their electron waves, caused by polarized injection of spin-flipped electrons due to spin-orbit interaction in the diffusion-region of the MWNT bulk.
Production and Characterization of MoSe2 Nanotubes by Electron Irradiation
Authors: Galván D. H. , Rangel R. , Adem E. 
Published: April 2011

AbstractIn this work, we report the production of MoSe2 (molybdenum diselenide) nanotubes formed by irradiating the samples with high doses of electron irradiation. The irradiation was performed on a 2 MeV Van de Graaff accelerator at the following conditions: voltage 1.3 MeV, current 5μA current, dose rate 25 kGy/min, and total dosage 1 MGy. We observed well-defined nanotubes of several nm long and few nm wide, which suppose to be hollow and capped at one end. As the level of irradiation was increased to 1 MGy, elongated onion-like structures were observed.
Interactions in Carbon Nanotubes and Polymer/Nanotubes Composites as Evidenced by Raman Spectroscopy (Invited)
Authors: Lefrant Serge , Buisson Jean-Pierre , Chauvet Olivier , Benoit Jean-Michel , Baibarac M. , Baltog I. , Bernier P. 
Published: April 2011

AbstractCarbon nanotubes systems have revealed large potentialities in terms of applications, especially at a nanometric scale. As a consequence, the different interactions which can take place can be of primary importance. In this paper, we report studies carried out on different carbon systems such as single-walled or multi-walled nanotubes and polymer/nanotubes composites. By using Raman spectroscopy, apart from the expected interactions between tubes in bundles which have initiated experiments on individual entities, we put in evidence strong chemical reactions at the interface metal/nanotubes when Ag or Au surfaces are used to carry out Surface Enhanced Raman Scattering experiments. We show in particular that a different behavior is observed for metallic and semiconducting tubes. Also, a high state of disorder is observed, together with the transformation of nanotubes to other carbon compounds. In the case of multi-walled nanotubes, theoretical calculations allow us to interpret the low frequency Raman modes by introducing interactions in concentric tubes, in rather good agreement with experiments. Finally, in polymer/nanotubes composites, an upshift of the radial breathing mode is observed and we show in this case that it originates from the dynamical stress applied by the polymer on the bundles in response to the breathing vibration.
Study in the Dispersion of Carbon Nanotubes
Authors: Bratcher Matthew , Gersten Bonnie , Ji Helen , Mays Jimmy 
Published: April 2011

AbstractIn the past, the dispersion of carbon nanotubes (CNTs) in both liquids and solids has been difficult due to the high surface interactions between the tubes. Dispersion of polymer CNT composites is important for such benefits as structural reinforcement of composites, the percolation threshold of CNT based conducting materials, and the thermal properties with the exploitation of the high surface area of CNTs. Here we discuss two approaches towards addressing dispersion of multiwalled nanotubes (MWNTs). One approach is the use of surfactant chemicals selected on the basis that they interact with CNT chemical groups. The second approach is the functionalization through covalent bonding of the CNTs with various polymers including polyethylenimine (PEI), and poly(methyl methacrylate) (PMMA). The two approaches were evaluated to determine whether covalent functionalization was more beneficial than the use of surfactants. Characterization of the dispersion was performed using various microscopy techniques.
Structural Characterization of Segmented Polyurethanes by Small Angle Neutron Scattering
Authors: Espada Loren I. , Mang Joseph T. , Orler E. Bruce , Wrobleski Debra A. , Langlois David A. , Hjelm Rex P. 
Published: April 2011

ABSTRACTThe beneficial mechanical properties of segmented polyurethanes derive from microphase separation of immiscible hard and soft segment-rich domains at room temperature. We are interested in the structure of the domains, how these are affected by hydrolytic aging, and how the structure is modified by low molecular weight plasticizers. To assessed the distribution of the plasticizer in polyurethane, we did small-angle neutron scattering measurements on mixtures of 23% hard segment poly(esterurethane) with different amounts of either non-deuterated or deuterated plasticizer. We analyzed the results using a simple model in which the contrast, Δ=H-, between the hard and soft segment-rich domains is varied by the amount of deuterated or hydrogenated plasticizer, using the fact that I(Q) ∼ Δ2. The result demonstrated that the plasticizer is largely associated with the soft segment rich domains. The structure of PESU with the chain extender of the hard segment was assessed after aging under hydrolytic conditions. The results show that the microphase structure coarsens and segregates and that the hard and soft segments segregated as a result of the loss of constraints from hydrolytic soft segment chain scission. The results on plasticizer distribution and the effects of hydrolytic aging give insight on the loss of mechanical properties that occur in each case.
Electrochemical Self-Assembled of Copper/Copper Oxide Nanowires
Authors: Kenane S. , Piraux L. 
Published: April 2011

ABSTRACTArrays of Cu/Cu 2 O nanowires are electrodeposited at room temperature from alkaline solutions of copper lactate in the nanopores of track-etched polymer membranes. Using the appropriate solution, the electrode potential spontaneously oscillates during the application of a constant cathodic current. Both the period of the oscillations and the composition of the nanowires can be controlled by varying the applied current density. A nanocomposite of copper and cuprous oxide is deposited at an applied current over which oscillations occur. In contrast, pure Cu or Cu 2O nanowires are obtained at deposition current out of the range of oscillation.
Formation of Supramolecular Assemblies by Modulating Self-Assembling Properties of Diacetylenic Phosphocholines
Authors: Singh Alok , Wong Eva M. , Spector Mark S. , Schnur Joel M. 
Published: April 2011

ABSTRACTDiacetylenic phospholipid dispersions in water produce tubules (500 nm diameter) and helices from their initial vesicular morphology as a function of temperature and concentration. A binary mixture consisting of diacetylenic phospholipid, 1,2 bis (tricosa-10, 12-diynoyl)-sn-glycero-3-phosphocholine and a short chain phospholipid, 1,2-dinonanoyl –sn-glycero-3-phosphocholine was studied to explore the morphological transformation of lipids into tubules to develop an approach to control and produce tubules of different diameters. Circular dichroic spectra not only indicated the chiral nature of these tubules, but also provided distinct spectral signatures differentiating micro- and nanotubules. The effects of temperature and lipid concentration on the formation and stability of tubules were also explored. An equimolar lipid mixture provided structures with uniform morphology, which were stable for several hours up to 36°C. The thermal stability of nanotubules makes them an attractive candidate for many practical applications including controlled release technology.
Shape Transition in Self-Organized InAs/InP Nanostructures
Authors: Gutiérrez H.R. , Cotta M.A. , de Carvalho M.M.G. 
Published: April 2011

ABSTRACTIn this letter we report the transition from self-assembled InAs quantum-wires to quantum-dots grown on (100) InP substrates. This transition is obtained when the wires are annealed at the growth temperature. Our results suggest that the quantum-wires are a metastable shape originated from the anisotropic diffusion over the InP buffer layer during the formation of the first InAs monolayer. The wires evolve to a more stable shape (dot) during the annealing. The driving force for the transition is associated with variations in the elastic energy and hence in the chemical potential produced by height fluctuations along the wire. The regions along the wires with no height variations are more stable allowing the formation of complex, self-assembled nanostructures such as dots interconnected by wires.
Imprinting the Quasi Bookshelf Texture of a Ferroelectric Liquid Crystal into Nano-scaled Polymer Fibrils
Authors: Kim S. H. , Suresh S. , Chien L.-C. 
Published: April 2011

ABSTRACTPolymer-stabilized ferroelectric liquid crystals (PSFLCs) are made by photopolymerizing 3% reactive mesogenic monomer on a quasi bookshelf texture of a ferroelectric liquid crystal (FLC). We observe the formation of nano-scaled polymer fibrils templated by the two dimensionally ordered host. The polymer fibrils capture the orientation of the host with thin polymer fibrils interweaving the smectic layers. The SEM study highlights the difference in morphology of the polymer fibrils depending on polymerization conditions; that is, polymerizing with or without the presence of an electric field. The polymer networks suppress the cone of rotation of FLC and thus, facilitate the switching and shorten the response time of the PSFLCs. We observed the threshold-less switching behavior in PSFLCs from samples polymerized with and without the field.
Carrier Transport Properties in Crosslinked Polymer / Liquid Crystalline Semiconductor Composite
Authors: Yoshimoto Naoki , Funahashi Masahiro , Hanna Jun-ichi 
Published: April 2011

ABSTRACTA novel composite system containing of liquid crystalline semiconductor and crosslinked polymer exhibited high hole mobilities with comparison of that of pure liquid crystalline molecules. The carrier transport properties were influenced by the polymerized conditions. The mobilities were independent on temperature and electric field in the case of mesophases polymerized samples. These carrier transport properties were essentially different of those of well-known molecularly doped polymers.
Synthesis, characterisation and liquid-crystalline phase transition studies on two higher homologues of 4O.m (m=14 and 16) series
Authors: Prabhu C. Rama Chandra , Pisipati V.G.K.M. 
Published: April 2011

ABSTRACTThe synthesis, characterization and phase transition studies of higher homologues of N(p-nbutoxybenzylidene)p-n-alkylanilines, Viz., 4O.m series (m=14 and 16) are carried out by thermal microscopy, differential scanning calorimetry and density. The compounds exhibit a phase variant of nematic and smectic-A. Density studies reveal a first order nature of IN transitions and a weak first order NA transitions. An estimate of pressure dependence of the phase transition temperatures using the volume and enthalpy data are presented. A comparison of these results with other reported results in nO.m and other compounds are presented.
Molecular Design Strategies for High Birefringence Liquid Crystals
Authors: Wu Shin-Tson 
Published: April 2011

ABSTRACTSome linearly conjugated liquid crystals with birefringence greater than 0.4 are discussed. UV stability of these high birefringence liquid crystals was systematically investigated. Both electronic conjugation and molecular structure make essential contributions to the observed degradation phenomena. Guidelines for designing stable high birefringence liquid crystals for displays and optical communications are discussed.
Multipodal Liquid-Crystalline Materials based on Ferrocene Cores
Authors: Meyer T. , Elsäßer R. , Shepperson K. J. , Vos D. , Donnio B. , Guillon D. , Goodby J. W. , Jutzi P. , Mehl G. H. 
Published: April 2011

ABSTRACTThe synthesis of multipodes based on substituted ferrocene groups and the results of the investigations of the liquid-crystalline phase properties of these materials, determined by optical polarising microscopy DSC and X-ray diffraction studies as central cores is reported.