Microporosity Development of Herringbone Carbon Nanofibers by RbOH Chemical Activation

The influence of different activation conditions, including activating agent/CNFs ratio, activation temperature, and He flow rate, on the pore structure development of herringbone carbon nanofibers (CNFs) was studied. The best results of activated CNFs with larger specific surface area can be achieved using the following optimized factors: RbOH/CNFs ratio = 4/1, activation temperature = ,and a He flow rate = 850 ml/min. The optimization of these three factors leads to high CNFs micropore volume, being the surface area increased by a factor of 3 compared to the raw CNFs. It is important to note that only the creation of micropores (ultramicropores principally) took place, and mesopores were not generated if compared with raw CNFs.

Development of SBR-Nanoclay Composites with Epoxidized Natural Rubber as Compatibilizer

The significant factor that determines the improvement of properties in rubber by the incorporation of nanoclay is its distribution in the rubber matrix. The simple mixing of nonpolar rubber and organically modified nanoclay will not contribute for the good dispersion of nanofiller in the rubbery matrix. Hence a polar rubber like epoxidized natural rubber (ENR) can be used as a compatibilizer in order to obtain a better dispersion of the nanoclay in the matrix polymer. Epoxidized natural rubber and organically modified nanoclay composites (EC) were prepared by solution mixing. The nanoclay employed in this study is Cloisite 20A. The obtained nanocomposites were incorporated in styrene butadiene-rubber (SBR) compounds with sulphur as a curing agent. The morphology observed through X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) shows that the nanoclay is highly intercalated in ENR, and further incorporation of EC in SBR matrix leads to partial exfoliation of the nanoclay. Dynamic mechanical thermal analysis showed an increase in storage modulus and lesser damping characteristics for the compounds containing EC loading in SBR matrix. In addition, these compounds showed improvement in the mechanical properties.

Effect of Premelting on Conductivity of DNA-Lipid Films

We have measured temperature-dependent (between 20 and80∘C) electrical conductivity and molecular structure (Raman spectroscopy) of DNA-lipid cast film. Our findings show that the conductivity is strongly influenced by premelting effects in the molecular structure starting near physiological temperatures (∼40∘C), prior to the global DNA denaturation.

Protein Fibrillar Hydrogels for three-Dimensional Tissue Engineering

Protein self-assembly into highly ordered fibrillar aggregates has attracted increasing attention over recent years, due primarily to its association with disease states such as Alzheimer's. More recently, however, research has focused on understanding the generic behavior of protein self-assembly where fibrillation is typically induced under harsh conditions of low pH and/or high temperature. Moreover the inherent properties of these fibrils, including their nanoscale dimension, environmental responsiveness, and biological compatibility, are attracting substantial interest for exploiting these fibrils for the creation of new materials. Here we will show how protein fibrils can be formed under physiological conditions and their subsequent gelation driven using the ionic strength of cell culture media while simultaneously incorporating cells homogeneously throughout the gel network. The fibrillar and elastic nature of the gel have been confirmed using cryo-transmission electron microscopy and oscillatory rheology, respectively; while cell culture work shows that our hydrogels promote cell spreading, attachment, and proliferation in three dimensions.

Processing and Electrochemical Property Characterization of Nanoporous Electrodes for Sustainable Energy Applications

Preparation and electrocatalytic reactions of nanoporous materials in biodegradable fluids were studied. Electrochemical etching was conducted to selectively extract metallic elements from alloys to form porous structures. Electrocatalytic properties of the porous electrodes were characterized. Comparative studies on the electrochemical activities of the nanoporous metallic electrodes with bulk metallic wire catalysts were performed. It is found that the current density at the nanoporous electrode is three times higher than that of the bulk electrode.

Nanostructural Formation of Pd-Co Bimetallic Complex on HOPG Surfaces: XPS and AFM Studies

A new single source approach was developed to synthesize Pd-Co nanoparticles using a bimetallic compound,[Et3NH]2[CoPd2(μ-4-I-3,5-Me2pz)4Cl4] (CoPd2), as a molecular precursor to obtain dispersed catalyst on highly ordered pyrolytic graphite (HOPG) surface, in view of preparing oxygen reduction catalysts for low temperature fuel cells. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) techniques were employed to characterize the nanostructure formations and to determine the composition and morphology of the complex on the HOPG. Results of high resolution XPS analysis (HR-XPS) revealed the binding energies corresponding to the atomic constituents of the precursor. When the precursor solution was placed on the surface of the HOPG, the bimetallic complex assumes a tubular structure and it appears that the surface of the HOPG offers a ground for the self-organization of nanostructural formations.

Nucleation and Growth of Crystalline Grains in RF-Sputtered TiO2Films

AmorphousTiO2thin films were radio frequency sputtered onto siliconmonoxide and carbon support films on molybdenum transmission electron microscope (TEM) grids and observed during in situ annealing in a TEM heating stage at250∘C. The evolution of crystallization is consistent with a classical model of homogeneous nucleation and isotropic grain growth. The two-dimensional grain morphology of the TEM foil allowed straightforward recognition of amorphous and crystallized regions of the films, for measurement of crystalline volume fraction and grain number density. By assuming that the kinetic parameters remain constant beyond the onset of crystallization, the final average grain size was computed, using an analytical extrapolation to the fully crystallized state. Electron diffraction reveals a predominance of the anatase crystallographic phase.

A Method for Fabricating Arrays of Nanopatterns with the Feature Size beyond Diffraction Limit

A convenient lithographic technique is proposed in this paper, which can be used to produce subdiffraction-limit arrays of nanopatterns over large areas (about several square centimeters). An array of polystyrene spheres (PS) is arranged on the surface of a layer of silver which has a thickness of about tens of nanometers. With the normal illumination light of wavelength 365 nm perpendicular to the substrate, PS can generate an array of optical patterns with high intensity at their contact points with silver. By designing the silver slab, the evanescent waves that carry subwavelength information about the optical patterns are substantially enhanced, while propagating components are restrained. In the photoresist which is on the other side of silver, the optical intensity is redistributed and subdiffraction-limit patterns are obtained after exposure and development. Simulation by finite-difference time-domain (FDTD) and experiments were carried out to verify the technique. The results show that by using PS with diameter of 600 nm, nanopatterns with dimension of less than 80 nm can be obtained.

Effect of Ammonium Nitrate on Nanoparticle Size Reduction

Ammonium nitrate was added to the spraying solution as a foaming agent to reduce the particle size of nanoparticles synthesized in the spray-pyrolysis process. Ammonium nitrate was effective in breaking the aerosol droplet size and generating nanoparticles that were of approximately one order-of-magnitude (from 200 to 20 nm) smaller diameter than those created in the absence of ammonium nitrate in the feed solution. This technique makes it possible to control the particle diameter of metallic nanoparticles below 20 nm.

Angular Dependence of Fluorescence Emission from Quantum Dots inside a Photonic Crystal

The fluorescence of emitters embedded in a photonic crystal is known to be inhibited by the presence of an incomplete photonic band gap or pseudogap acting in their emission range. Here, we present a study of the angular dependence of the fluorescence emission of emitters embedded in a photonic crystal. Our results clearly show an angular dependence of the fluorescence emission, which is caused by the presence of an incomplete 3D band gap.