bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relaxation of Aggregates in a Jamming Colloidal Suspension After Shear Cessation
Authors: Ianni Francesca , Lasne David , Sarcia Regis , Hebraud Pascal 
Published: April 2011

ABSTRACTThe reversible formation of aggregates in a shear thickening, concentrated colloidal suspension is investigated through speckle visibility spectroscopy, a dynamic light scattering technique recently introduced [1]. Formation of particle aggregates is observed in the jamming regime, and their relaxation after shear cessation is monitored as a function of the applied shear stress. The aggregate relaxation time increases when a larger stress is applied. Several phenomena have been proposed to interpret this behavior: an increase of the aggregate size, or a closer packing of the particles in the aggregates.1. P.K. Dixon, D.J. Durian, Phys. Rev. Lett. 90, 184302 (2003).
Polydiacetylene Liposomes Attached to Glass Fibers for Fluorescent Bioassays
Authors: Reppy Mary A , Pindzola Bradford A 
Published: April 2011

ABSTRACTPolydiacetylene (PDA) is a conjugated polymer that changes its fluorescent state in response to environmental changes and can act as a transducer to convert molecular interactions into a discernable output measurable in the macroscopic world. Energy transfer to fluorophores can further enhance the fluorescent signal. Diacetylene liposomes can be prepared with phospholipids and other cell membrane components in the liposomes, and photopolymerized. PDA liposomes have been used for absorbance based detection of biological targets; however, moving to fluorescence detection gives increased sensitivity and also allows sensing from PDA structures deposited on opaque membranes. Unfortunately, PDA liposomes are prone to aggregation, particularly in the presence of divalent cations. Many enzymes require divalent cations such as Mg2+, Mn2+, Ca2+, etc., as co-factors; the tendency of PDA liposomes to aggregate in the presence of these cations limits their use as a platform for detection of enzymatic activity. We have developed methods for attaching PDA liposomes to glass fiber membranes, via thiol-epoxide coupling chemistry, for use in bio-assays and have seen that these materials can be used in place of PDA liposome solutions. We present here the attachment of PDA liposomes to glass fiber membranes in 96-well format, cryogenic TEM scans of the attached liposomes and the use of these materials in fluorescence assays to detect the activity and inhibition of phospholipase A2.
AC Loss Characteristics of Stacks of YBCO Coated Conductors
Authors: Grilli Francesco , Ashworth Stephen P. , Stavrev Svetlomir 
Published: April 2011

ABSTRACTPractical applications of YBCO coated conductors (CC) involving superconducting coils will utilize tapes packed together in an arrangement resembling a vertical stack. In such configuration there is an important electromagnetic interaction between the tapes, which strongly influences the loss characteristic of the device.In the presence of an external magnetic field, the losses are reduced compared to an isolated tape because of the reduced aspect ratio of the conductor and, at least for low fields, because of an effective screening of the central part of the stack. On the contrary, in the case of AC transport current, the losses tend to increase due to the enhancement of the local field caused by the interaction of the self-field produced by neighboring tapes. In practical situations the conductor is usually subjected to both transport current and magnetic field, so that there is a trade-off between the two effects.In this paper we investigate, both experimentally and by means of finite-element method calculations, the ac loss behavior of a stack composed by a finite number of tapes in different working conditions, and we compare the AC losses to the ones of non-interacting tapes in order to determine if the use of stacked tapes is advantageous from the point of view of power dissipation.
Stretched Polymer Nanohairs by Tailored Capillarity and Adhesive Force
Authors: Jeong Hoon Eui , Lee Sung Hoon , Kim Pilnam , Suh Kahp Y. 
Published: April 2011

ABSTRACTWe present a simple method for fabricating high aspect-ratio polymer nanostructures on a solid substrate by sequential application of molding and drawing of a thin polymer film. In this method, a thin polymer film is prepared by spin coating on a solid substrate and the temperature is raised above the polymer¡¯s glass transition while in conformal contact with a poly(urethane acrylate) (PUA) mold having nano-cavities. Consequently, capillary forces induces deformation of the polymer melt into the void spaces of the mold and the filled nanostructure was further elongated upon removal of the mold due to tailored adhesive force at the mold/polymer interface. The optimum value of the work of adhesion at the mold/polymer interface ranged from 0.9 to 1.1 times that at the substrate/polymer interface. Below or above this range, a simple molding or detachment occurred, corresponding to earlier findings.
Coaxial Electrospinning for Nanostructured Advanced Materials
Authors: Loscertales Ignacio G. , Díaz Gómez Juan E. , Lallave M. , Rosas J. M. , Bedia Jorge , Rodríguez-Mirasol J. , Cordero T. , Marquez M. , Shenoy S. , Wnek G. E. , Thorsen T. , Fernández-Nieves A. , Barrero A. 
Published: April 2011

ABSTRACTElectro-hydro-dynamic (EHD) compound jets, with diameters in the micro and nanometric size range, from conical menisci of two co-flowing liquids, is a consolidated platform for the production of nanofibers with inner structure, in a process so-called coaxial electrospinning or co-electrospinning. In contrast to other multi-step template based procedures, the EHD methodology is much more simple and general since, firstly, a solid template is needless and, secondly, the process is seldom affected by the chemistry of the liquids. This gentle process allows selecting the liquid precursors depending on the application sought for the nanofibers. Here, we review different products obtained by this EHD technique: (1) solid and hollow carbon nanofibers from different precursors (polyacrylonitrile, polyvinylpyrrolidone and lignin), (2) nanofibers of biocompatible polymers encapsulating liquids in the form of beads, (3) spinning nanofibers of alginate and (4) in-fiber encapsulation of active microgels.
Effect of Strain Rate on the Mechanical Behavior of 10-micron Long Polymeric Nanofibers
Authors: Naraghi Mohammad , Chasiotis Ioannis , Dzenis Yuris , Wen Y. , Kahn Hal 
Published: April 2011

ABSTRACTThe strain rate mechanical behavior of 12-micron long polymeric nanofibers was investigated. Experiments were carried out by a novel method that employs a MEMS-based leaf spring load cell attached to a polymeric nanofiber that is drawn with an external PZT actuator. The elongation of the fiber and the deflection of the load cell were calculated from optical microscopy images by using Digital Image Correlation (DIC) and with 65 nm resolution in fiber extension. The nanofibers were fabricated from electrospun polyacrylonitrile (PAN) with MW = 150,000 and diameters between 300-600 nm. At strain rates between 0.00025 s−1 to 0.025 s−1 the fiber ductility scaled directly with the rate of loading while the tensile strength was found to vary non-monotonically: At 0.00025 s−1 material relaxations allowed for near-uniform fiber drawing with up to 120% ductility and 120 MPa maximum tensile strength. At the two faster rates the tensile strength scaled with the rate of loading but the fiber ductility was the result of a cascade of localized deformations at nanoscale necks with relatively constant wavelength for all fiber diameters.
Polarized Luminescence from Single Polymer Nanowires and Aligned Nanowire Arrays
Authors: O'Carroll Deirdre , O'Riordan Alan , Redmond Gareth 
Published: April 2011

ABSTRACTThe synthesis of poly(9,9-dioctylfluorene) conjugated polymer nanowires using the method of solution assisted wetting of nanoporous alumina membrane templates is reported. Polymer nanowires (approx. 109 per template) with a diameter of approx. 200 nm are obtained. Photoluminescence from isolated nanowires fluidically-aligned at glass substrates is found to be dominated by emission from the planar beta-phase of the polymer. The wires also exhibit polarized light emission suggestive of axial alignment of beta-phase segments within the nanowires. Dense arrays of aligned nanowires exhibiting anisotropic emission are also demonstrated.
Influence of Particle Size and Thickness of Material on Anti-voltage Strength of Energy-storage Composite
Authors: Luo Dabing , Guo Yan , Hua Hao , Liu Hanxing , Ouyang Shixi 
Published: April 2011

ABSTRACTAfter combining the PVDF and BST powders with different particle sizes, the anti-voltage strengths of composites was tested. Although the concentrates of ceramic were all the same, their anti-voltage strengths were distinguished. The results showed that the bigger particles or less thickness of material could benefit to the anti-voltage strength and ultimately enhanced the energy storage density of composites. Moreover, the distribution of particle dimension also influenced the strengths of materials. Composite with homogeneous particles performed higher strength than that of composites with inhomogeneous particles.
Influence of the Crystallisation Kinetics on the Microstructural Properties of α-PVDF
Authors: Silva Marco Pinto , Sencadas Vitor , Rolo Anabela G , Botelho Gabriela , Machado Ana Vera , Lanceros-Mendez Senentxu 
Published: April 2011

ABSTRACTThe kinetics of the isothermal crystallization from the melt at different crystallisation temperatures and the melting behaviour of Poly(vinylidene fluoride) (PVDF) in the alpha phase has been investigated. The variation of the microstructure of the samples crystallized at different temperatures was monitored with time by Optical Microscopy. The correlation between microstructure and kinetic parameters allows the tailoring of the microstructure by choosing the crystallisation conditions of the samples. Raman and Infrared Transmission Spectroscopy also show the appearance of the γ-phase for higher crystallisation temperatures. The influence of the crystallisation kinetics on the degree of crystallinity of the samples will be also presented and discussed.
Sensitive Impurity Detection and Recognition in Inert Gaseous Media with SnO2 Based Gas Sensor Microarray
Authors: Goschnick Joachim , Schneider Thomas 
Published: April 2011

ABSTRACTContrary to the conventional use of semi-conductive metal oxides as gas detectors for components in air the analytical performance of segmented SnO2-layers were investigated to detect and discriminate impurities in inert gases such as nitrogen or helium. A broad variety of technical processes require high purity inert gases which have to be kept under permanent surveillance to detect leaks to the atmosphere, a gas release of contaminated fittings or other contaminations. The unique gradient gas sensor microarray of the Karlsruhe micronose (KAMINA) was equipped with segmented layers of either nanoparticle or sputtered SnO2 layers and exposed to a high purity nitrogen flow of 1lit/min into which temporarily model impurities have been admitted with a variety of concentrations. Pulsed exposures were performed to nitrogen containing oxygen (0.2 to 10 vol %), water vapour (5 to 15 % relative humidity) and 2-propanol as well as tetrachloromethane in the ppm range. For all model contaminations a fast and sensitive response has been found. The measured concentration dependence revealed a detection limit of about 0.01 vol% for oxygen and 0.03% of relative humidity for an operating temperature of the KAMINA chip at 325..273 °C. The detection limits for the organic compounds were even found to be in the lower ppb range. The conductivity patterns obtained from the simple segmentation microstructure of the KAMINA SnO2 layers operated with a temperature gradient were evaluated by a Principal Component Analysis (PCA) which proved an appropriate gas discrimination power to distinguish pure nitrogen and the different kinds of contaminations for both types of SnO2 layers. However, the sputtered layer showed better detection limits while the nanoparticle layers offered a better sensitivity, i.e. a higher slope of the concentration dependence.
Synthesis and Characterization of Tunable and Highly Transparent Thick Layers of Nanocomposites Based on Methacrylates and Silica Nanoparticles
Authors: Simone Giuseppina , Perozziello Gerardo , Tagliaferri Vincenzo , Szita Nicolas 
Published: April 2011

ABSTRACTWe present a nanocomposite material based on functionalized silica nanoparticles in a methacrylate matrix. The nanocomposite material is synthesized without addition of a co-solvent, which enables the spin-coating of thick and defect-free layers of several tens of micrometers with smooth surfaces. SEM analysis indicates uniform distribution of the nanoparticles in the methacrylate matrix, and pinhole-free surfaces suitable for applications in optics. For optical characterization, the refractive index of the material for different silica concentrations is reported, and propagation losses in the UV/VIS range discussed. The tuning of the refractive indices can be applied towards the realization of low-loss passive optical waveguides. As a first step towards this goal, the processibility of the nanocomposite material for microfluidic applications, and the realization of a planar optical waveguide are demonstrated.
Laser Deposited Ag3SbS3 and Tl3SbS3 Nanoscale Thin Films as Potential Electric Field Sensors
Authors: Khlyap Halyna , Panchenko Lyudmila , Laptev Victor , Shkumbatiuk Petro , Bilozertseva Violetta 
Published: April 2011

ABSTRACTPhase composition and electrical properties of Ag(Tl)SbS amorphous films obtained by pulse laser deposition technology are investigated. The films deposited on crystalline NaCl and Kcl substrates are amorphous with crystalline phase inclusions. Room-temperature current voltage characteristics showed a good electro-sensitivity of the films under applied bias up to 10 V and a space-charge-limited current was registered as a principal component of the charge carrier transport.
Effects of Post Calcination Treatment on Photoluminescence and Structural Properties of Scheelite-type LiEuW2O8Nanocrystals Synthesized by Glycothermal Reaction
Authors: Kasuya Ryo , Isobe Tetsuhiko , Yamao Shinobu , Sfihi Hocine 
Published: April 2011

ABSTRACTThe scheelite-type LiEuW2O8(LEW) nanoparticles of ∼50 nm in diameter were synthesized from lithium acetate, europium (III) acetate and phosphotungstic acid in 1,4-butylene glycol at 300°C for 2h by autoclave treatment. Post calcination treatment at 600°C for 2 h enhanced the photoluminescence at 465 nm due to the 4f - 4f transition excitation of Eu3+by a factor of 24.4, and due to charge transfer (CT) excitation from either O2−or WO42−to Eu3+by a factor of 5.8. Convergent beam electron diffractmetry and the compositional analysis revealed the non-stoichiometric structure of the scheelite-type LEW nanocrystals. Raman spectroscopy also detected the WO4vibrational modes due to the tetragonal scheelite-type LEW. Solid-state7Li single pulse excitation MAS NMR indicated the existence of at least three Li sites in the samples. We conclude that the following three factors are improved by calcination to increase the f-f transition probability of Eu3+: (i) a distribution of the Eu3+– Eu3+distance, (ii) the symmetry of Eu3+polyhedra, (iii) the symmetry of tetrahedral WO4units in the vicinity of Eu3+polyhedra. Furthermore, oxygen is provided for non-stoichiometric LEW during calcination to enhance the CT probability.
Interactions of Carbon Nanomaterials With Mammalian Cells
Authors: Raja Pavan M. V. , Connolley Jennifer , Ci Lijie , Ganesan Gopal P. , Ajayan Pulickel M. , Nalamasu Omkaram , Thompson Deanna M. 
Published: April 2011

ABSTRACTDespite their diverse application potential, carbon nanotubes (CNT) have adverse effects in vitro, and in vivo. Previous research has focused on the in vitro cytotoxic impact of CNT aggregates and associated nanoparticulate impurities. In this study, we compared the single-walled carbon nanotube (SWNT) aggregates, and their associated finely dispersed, non-aggregated carbon nanomaterials on rat aortic smooth muscle cells (SMC), through filtration of the aggregates from the CNT-treated cell culture media. In general, our research shows that the removal of single-walled carbon nanotube (SWNT) aggregates from cell culture test media inhibited the growth in SMC to a lower extent than the corresponding unfiltered media at pre-filtered SWNT dosages below 0.10 mg/ml. We also found suspended nanoparticles (likely amorphous and graphitic carbon associated with the SWNT) and a small quantity of SWNT in the filtered media may have contributed to the observed cell growth inhibition by the filtered media. In addition, we compared the effect of SWNT, a nano-sized material, with activated carbon (AC), a nanoporous, microparticulate material, on SMC growth. AC (0.1 mg/ml) was found to be less inhibitory to SMC growth than the SWNT aggregates and suspended matter (0.1 mg/ml), potentially implying an inverse proportionality between carbon nanomaterial size regimes and cell growth inhibition.
Spherical Carbon Nanostructures - A Versatile Material for Sensing and Energy Storage
Authors: Friedel Bettina , Greulich-Weber Siegmund 
Published: April 2011

ABSTRACTMonodisperse smooth carbon nanospheres were synthesized via preparation and complex subsequent multistage pyrolysis of spherical melamine formaldehyde copolymer microparticles. The diameters of optained carbon spheres were located between several tens to several hundreds nanometers depending on the size of used initial copolymer particles. During the conversion of copolymer to carbon, the spheres pass strong shrinking of more than 80 % without any deformation. They meet the high quality standards of common prepared and used polymer and silica spheres and are therefore a promising material with great potential. Carbon nanoparticles could be used in a wide range of applications, such as for gas storage, fuel cells, sensing, catalyst support, separation and purification, supercapacitors or lithium-ion batteries, and photonic bandgap materials. Especially for the last mentioned usage monodispersity and a perfect spherical shape are very important. So-called synthetic opals from carbon spheres have been grown by sonic-supported sedimentation and a photonic bandgap in the infrared region has been found. Due to their high thermal resistance under non-oxidizing conditions carbon opals are also suitable as template for inverse opals. The structure of the spheres has been studied during different stages of carbonization by scanning electron microscopy, nuclear magnetic resonance and fourier transform infrared spectroscopy.
Highly Sensitive Surface Plasmon Resonance Sensor on Nanoscale Bioactive Surfaces for Specific Detection of Tri-Nitro Toluene
Authors: Singh Praveen , Onodera Takeshi , Matsumoto Kiyoshi , Miura Norio , Toko Kiyoshi 
Published: April 2011

ABSTRACTA nano-scale biosensor chip surface was fabricated using dinitro-phenylated key hole limpet (DNP-KLH) protein conjugate as ligand supported by underlying 11-amino 1-undecanethiol hydrochloride(AUT) self assembled monolayer (SAM) and bis sulfosuccinimidyl suberate(BS3) as crosslinker. Bioactive thin films were fabricated over gold chip via layer-by-layer self assembly methods. Biomolecular interaction between substrate specific anti-TNT antibody and DNP-KLH conjugate surface was monitored through surface plasmon resonance based optical sensor. The quantitation of tri-nitro toluene(TNT) on this bioactive surface was done using the solution based competitive inhibition assay. The DNP-KLH surface biosensor has shown a detection limit of 0.14 ng/ml(140 ppt) for TNT molecule. The detection limit of surface plasmon resonance(SPR) biosensor was further enhanced by using goat anti mouse antibody to the 0.002 ng/ml for TNT analyte. This TNT specific biosensor holds the promise to be one of most sensitive sensor surface under indirect competitive assay format. A short injection (12 sec) of 10 mM Glycine-HCl solution was found adequate for regeneration of DNP-KLH surface for repeated use.
Electrochemical synthesis of a ZnO nanowire field-effect transistor
Authors: Wade Travis Lee 
Published: April 2011

ABSTRACTAluminum wires are electrochemically sculptured into bi-directional templates for the growth and contacting of nanowires as three terminal devices. The utility of this nanostructured micro-template is demonstrated by a ZnO nanowire surrounding gate field-effect transistor. This bottom-up approach to a 3-D nanowire transistor is unique in that it can be almost entirely fabricated in a beaker using aqueous, room-temperature electrochemistry.
Cytotoxicity of the Functionalized Gold and Silver Nanorods
Authors: Kuo Chiung-Wen , Lai Jun-Jung Lai , Chen Peilin 
Published: April 2011

ABSTRACTThe cytotoxicity of various surface functionalized gold and silver nanords was measured by MTT assays for two cell lines, fibroblast and HeLa. It was found that the functionalized nanorods with 200 nm diameter and length up to a few micrometer can be readily internalized by both types of cells regardless of the surface functionalization. However, the cytotoxicity of the nanorods was found to depend on the polarity of the surface charge. The positively charged amino end group on the nanorod surface was found to be the least toxic whereas the negatively charged carboxylic acid end group on the nanorod surface caused lots of cell death. In general, the functionalized nanorods were found to be more toxic than the serum coated nanorods.
Functional Patternings Fabricated using Molecularly Imprinted Polymer; Molecular Recognitions for Chemical Detection
Authors: Choi Kyung 
Published: April 2011

ABSTRACTWe present functional patterns fabricated using functional polymers. The functional polymer is MIP (molecularly imprinted polymer) system, which can be produced through “molecular imprinting” to create “synthetic receptor or binding sites” for bio/chemical detection technology. Those binding sites have specific molecular recognition functions for targeting organic or bio molecules. MIP's patterns in the micro-scale were fabricated for chemical sensors, diagonostic bio-sensors, and for drug delivery systems. We also obtained homogeneous MIP's micro-particles, which have high affinity receptor sites only using a microfluidic reactor.
Detection of Cell Surface Protein with Surface Enhanced Raman Spectroscopy
Authors: Tay Li-Lin , Hu Qingyan , Noestheden Matthew , Pezacki John 
Published: April 2011

ABSTRACTIn this study, HeLa cells were transfected to express a recombinant transmembrane domain of the platelet-derived growth factor receptor. Silver nanoparticle (Ag-NP) functionalized with terminal hydrazide was employed to specifically target the ketone-conjugated cell surface proteins. In addition, a nitrile functional group was incorporated onto the Ag nanoprobe to provide unique vibrational signature (∼ 2230 cm−1) in a window which is free from other cellular components. The designed Ag nanoprobe functions as both recognition and transduction elements in the detection of the expressed cell surface protein. Scanning electron microscopy and surface enhanced Raman spectroscopy (SERS) imaging of the nanoparticle (NP) labeled HeLa cells revealed that all the observed intense SERS signals originated from aggregated NPs. Although isolated Ag-NPs is capable of SERS enhancement, its enhancement factor is beyond the detestability of such imaging experiments. The results have implication in the future design of SERS nanosensors for in vivo detection application.