Materials Literature
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The adsorption behavior of a low charge density cationic polyelectrolyte to cellulosic fibers has been studied. Cationic dextran served as a model polyelectrolyte, as it can be prepared over a range in molecular mass and charge density. The adsorption behavior of the cationic dextran was measured in electrolyte-free c…
The ultimate goal of nanotechnology is the design and fabrication of nanosize building blocks with multiple functionalities and their assembly into large-scale functional structures that can be controllably manipulated. Here we show that hybrid inorganic multisegmented nanowires, with hydrophobic carbon nanotube tails…
We first summarize the classical arguments that the vast majority of glass-forming liquids require more than one ‘order’ parameter for their description. Critiques against this conventional wisdom are then presented, and it is argued that the matter deserves to be reconsidered in the light of recent experimental devel…
We study current-voltages and low-frequency noise characteristics of the metal-porous silicon-silicon single crystal-metal structure with 50% and 73% porosity of porous silicon. The study is performed in dry air and in a mix of dry air with carbon monoxide of different concentrations. The Hooge noise parameter and the…
An introduction is given to structure factor determination by means of neutron diffraction. The method of isotopic substitution, which allows us to separate the partial correlation functions, is also presented. Suitable instruments, the experimental procedures, and corrections are described. Other less-conventional te…
This paper deals with the sensorless characterization of magnetic materials under nonperiodic conditions. A volt-amperometric method based on general physical principles has been adopted to do the measurements. Starting from the concept of magnetic hysteresis as a multibranch nonlinearity with nonlocal memory, we prov…
Multiwalled carbon nanotubes (MWNTs) have a very high absorbance in the near-infrared (NIR) region of the electromagnetic spectrum. It is demonstrated that the temperature of MWNTs, measured using infrared thermography during NIR laser irradiation, is much higher than that of other carbonaceous materials such as graph…
A pressure counterpart of the Vogel–Fulcher–Tammann (VFT) equation for representing the evolution of dielectric relaxation times or related dynamic properties is discussed: τ( P ) = τ 0 P exp[ D P Δ P ( P 0 −Δ P )], where Δ P = P − P SL , P 0 is the ideal glass pressure estimation, D P is the pressure fragility streng…
We present the phase diagram of a colloid-polymer mixture in which the radius a of the colloidal spheres is approximately the same as the radius R of a polymer coil ( q = R / a ≈1). A three-phase coexistence region is experimentally observed, previously only reported for colloid-polymer mixtures with smaller polymer c…
A new colloidal stabilization mechanism, known as nanoparticle "haloing" (Tohver, V.; Smay, J. E.; Braem, A.; Braun, P. V.; Lewis, J. A. Proc. Natl. Acad. Sci. U.S.A. 2001, 98, (16), 8950-8954), has been predicted theoretically and inferred experimentally in microsphere-nanoparticle mixtures that possess high charge a…
Nanotechnology based detection of threat agents, such as explosives and biological agents, has been a top research priority at the Center for Chemical Sensors Development at the Department of Chemistry of the University of Puerto Rico-Mayaguez (UPRM). Nanoparticles are of fundamental interest since they possess unique…
A simple wide-view and broadband circular polarizer comprising of a linear polarizer and two uniaxial films is proposed to enhance the viewing angle of transflective liquid crystal displays (LCDs). For the transmissive mode, over the entire 90deg viewing cone, the normalized light leakage from two stacked circular pol…
Dispersions of carbon nanotubes (CNTs) in liquid crystals (LCs) have attracted attention due to their unique properties and possible applications in photonics and electronics. However, these are hard to stabilize, and the loading level in the equilibrium state in LC hosts is small. A practical way to monitor the quali…
On decreasing the temperature T , the correlation time τ of supercooled water displays a dynamic crossover from non-Arrhenius dynamics (with T -dependent activation energy) at high T to Arrhenius dynamics (with constant activation energy) at low T . Simulations for water models show that this crossover occurs at the l…
The dielectric properties of the low and high density amorphous ices are discussed in terms of those for supercooled water and crystalline ices, and also used to evaluate the transitionbehaviour up ...
Mesostructured microspheres formed by aerosol-assisted self-assembly of a gelable block copolymer, poly(3-(triethoxysilyl)propyl methacrylate)- block-polystyrene (PTEPM -b-PS), were studied by a combination of small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). When the copolymer compositio…
Ni 1− x Co x alloy nanoparticles ( x = 0.25, 0.50, 0.75), with diameters in the range 8–18 nm were uniformly attached on the surface of multi-walled carbon nanotubes (MWNTs) by electroless plating, and were characterized by transmission electron microscopy, energy-dispersive x-ray spectrometry, x-ray diffraction analy…
A two-beam second-harmonic generation technique is developed to calibrate the magnitude of the second-order nonlinear optical susceptibility components of surface and bulk (multipolar origin) of isotropic materials. The values obtained for fused silica calibrated against ChiXXX of crystalline quartz are chi parallel p…
Chemical sputtering of amorphous hydrogenated carbon films by exposure to nitrogen molecular ions and combined exposure to nitrogen molecular ions and atomic hydrogen was studied as a function of ion energy in the range 30-900 eV and as a function of temperature between 110 and 350 K.The yield for nitrogen ions alone…
Copper sulfide-core/carbon-shell cables and spheres have been prepared by a simple hydrothermal method. The obtained CuS/C cables and spheres were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman, Fourier transform infrared spectroscopy, photoluminescence, and U…