Materials Literature
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A new gas injection/specimen heating holder is developed for the purpose of in situ observation of gas reaction of materials at high temperatures in a transmission electron microscope at near-atomic resolution. A fine tungsten wire is employed as a heating element of the holder and a battery is used as the power sourc…
We report the adsorption isotherms and the isosteric heats of adsorption of pure methane, ethane, and CO2 and a mixture of methane and CO2 in the periodic mesoporous silica MCM-41 using a multicomponent adsorption calorimeter of the Tian-Calvet type, looking in particular at the degree of heterogeneity in the adsorpti…
Single walled carbon nanotubes (SWNTs) have been functionalized in a mixture of 96% sulfuric acid and ammonium persulfate, using sodium nitrite to produce intermediate diazonium salts from substituted anilines. These afford unbundled functionalized SWNTs from bulk bundled SWNTs. This new process eliminates the need fo…
A novel ultrathin enzymatically degradable multilayered film using DNA as building blocks was fabricated by the layer-by-layer (LbL) technique. The UV-vis spectrometry and AFM experiments showed that the buildup of DNA and poly-L-lysine (PLL) was a kind of "exponentially growing films". The dye adsorption experiment s…
The origin of a recently reported peculiar phenomenon---polarization reversal against the applied electric field in ferroelectric thin films [M. Aplanalp and P. G\"unter, Ferroelectrics 258, 3 (2001), T. Morita and Y. Cho, Appl. Phys. Lett. 84, 257 (2004)]---has been identified. The phenomenon is observed when poling…
Abstract Summary: Ultrasonic irradiation was employed to prepare polypyrrole (PPY)/Fe 3 O 4 magnetic nanocomposite by chemical oxidative polymerization of pyrrole in the presence of Fe 3 O 4 nanoparticles. This approach can solve the problem in the dispersion and stabilization of inorganic nanoparticles in polymer. Th…
A new beamline, fully dedicated to X-ray powder diffraction (XPD) measurements, has been installed after the exit port B of the bending magnet D10 at the Brazilian Synchrotron Light Laboratory (LNLS) and commissioned. The technical characteristics of the beamline are described and some performance indicators are liste…
Abstract Hybrid thin films of conjugated polymers and CdSe nanoparticles have been fabricated by using a layer‐by‐layer (LbL) approach driven by covalent coupling reactions. This method permits facile covalent crosslinking of the polymer/nanoparticle interlayers in common organic solvents, which provides a general rou…
We extensively study the phase diagram of a diblock copolymer melt confined in a cylindrical nanopore using real-space self-consistent mean-field theory. We discover a rich variety of new two-dimensional structures that have no analogue in the unconfined system. These include nonhexagonally coordinated cylinder phases…
A recently proposed microscopic activated barrier hopping theory [K. S. Schweizer and E. J. Saltzman, J. Chem. Phys. 119, 1181 (2003)] of slow single-particle dynamics in glassy liquids, suspensions, and gels is derived using nonequilibrium statistical mechanics. Fundamental elements underlying the stochastic nonlinea…
[reaction: see text] Oxidation of alkynes to alpha-dicarbonyl derivatives through a convenient one-pot procedure via a Brønsted acid-promoted "hydration" and a DMSO-based oxidation sequence has been achieved in high yields. The scope and limitations of the reaction have also been investigated.
The 19ID undulator beamline of the Structure Biology Center has been designed and built to take full advantage of the high flux, brilliance and quality of X-ray beams delivered by the Advanced Photon Source. The beamline optics are capable of delivering monochromatic X-rays with photon energies from 3.5 to 20 keV (3.5…
At low pressure, free surfaces play a crucial role in the melting transition. Under pressure, the surface of the sample is acted upon by some pressure transmitting medium. To examine the effect of this medium on melting, we performed Monte Carlo simulations of a system of argon atoms in the form of a slab with two bou…
Based on experimental 59Co-NMR data in the temperature range between 0.1 and 300 K, we address the problem of the character of the Co 3d-electron based magnetism in Na0.7CoO2. Temperature dependent 59Co-NMR spectra reveal different Co environments below 300 K and their differentiation increases with decreasing tempera…
The Thomas-Fermi (TF) approximation for the static dielectric constant of a three-dimensional electron liquid can be derived from minimizing the TF local-density approximation for the kinetic-energy functional. Here we show that this connection between energy functionals and model dielectric constants is not an artifa…
We study solid surface morphology created by off-normal ion-beam sputtering with an atomistic, solid-on-solid model of sputter erosion. With respect to an earlier version of the model, we extend this model with the inclusion of lateral erosion. Using the 2-dimensional structure factor, we found an upper bound $μ\simeq…
The work describes the capabilities of Laser Scanning Microscopy (LSM) as a spatially resolved method of testing high_Tc materials and devices. The earlier results obtained by the authors are briefly reviewed. Some novel applications of the LSM are illustrated, including imaging the HTS responses in rf mode, probing t…
We propose and demonstrate a spatial partition method for the high-frequency photo-response of superconducting devices correlated with inductive and resistive changes in microwave impedance. Using a laser scanning microscope, we show that resistive losses are mainly produced by local defects at microstrip edges and by…
The flow anisotropy of a concentrated colloidal suspension at the jamming transition is studied. It is shown that the use of rough spherical particles reduces the hydrodynamic lubrication forces between adjacent colloids and makes possible the study of the stress tensor anisotropy. At low shear rates, the suspension e…
The work in this paper analyses the applicability of carbon nanotube (CNT) bundles as interconnects for VLSI circuits, while taking into account the practical limitations in this technology. A model is developed to calculate equivalent circuit parameters for a CNT-bundle interconnect based on interconnect geometry. Us…