Materials Literature
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Poly(vinyl alcohol)- (PVA) and Cu(OH) 2 −PVA-intercalated graphite oxide (GO) were prepared and characterized in detail. The I c values of PVA-intercalated GO varied widely in the range 1.32−2.24 nm. In the case of PVA-intercalated GO, a stepwise increase of the I c value of ∼0.5 nm was observed along with the increas…
Argon plasma treatment and subsequent atmospheric exposure have been used to incorporate new oxygen functionalities at the surface of polystyrene (PS) and polypropylene (PP). High-energy resolution X-ray photoelectron spectroscopy (XPS) has yielded molecular information regarding the site of modification in both polym…
In tetragonal zirconia, the cation is coordinated by two interpenetrating tetrahedra of oxygen ions, implying two different cation-oxygen bond lengths. Neutron powder diffraction was used to study tetragonal ZrO2–2 mol% Y2O3 incorporating various amounts of the different tetravalent ions Ge, Ti, Sn and Ce. Precise and…
This paper discusses the design and performance of a 256 X 256 bolometer-type uncooled infrared detector. First, model calculations are carried out to clarify the relations of the noise equivalent temperature difference (NETD) to the electrical properties of the bolometer material. The properties are mainly resistivit…
Measurement of second-order nonlinear optical response of molecules by hyper-Rayleigh scattering (HRS) is often affected by the presence of two-photon excited fluorescence. For crystal violet we found experimentally that both HRS and two-photon absorption induced fluorescence give the same depolarization ratio for the…
Raytheon Sensors and Communications Systems has developed a prototype infrared imaging rifle-sight using an uncooled, microbolometer FPA. The Longwavelength Staring Sensor (LWSS) has been characterized by NVESD, where it demonstrated NETD and MRT values that are unsurpassed for uncooled FPA technology. The NVESD-measu…
A density functional theory for bulk and surface elastic constants of biaxial nematic liquid crystals is developed. It is based on a functional Taylor expansion of the free energy of a distorted biaxial nematic with respect to the one-particle distribution function. Detailed microscopic expressions for the biaxial ela…
Rate constants and activation parameters for water exchange on the Rh(III) hydrolytic dimer [(H(2)O)(4)Rh(&mgr;-OH)(2)Rh(H(2)O)(4)](4+) were determined using (17)O NMR spectroscopy as a function of temperature (308-323 K) and pressure (0.1-150 MPa). This represents the first variable-pressure (17)O NMR study conducted…
Hydrotalcite-like compound (HTlc) of Mg 0.3 Co II 0.6 Co III 0.2 (OH) 2 (NO 3 ) 0.2 ·H 2 O has been synthesized for the first-time by coprecipitation in an ammoniacal solution and hydrothermal treatments under various O 2:N 2 atmospheres. Using elemental analysis and redox titration, it is found that about 23% of the…
Today, a large number of uncooled infrared detector developments are under progress due to the availability of silicon technology that enables realization of low cost 2D IR arrays. LETI/LIR, which has been involved in this field for a few years, has chosen resistive amorphous silicon as thermometer for its uncooled mi…
We present results of Brownian dynamics simulations of polymer brushes under steady and oscillatory shear. The brush is sheared by a bare surface and the resulting solvent velocity and polymer dynamics are solved self-consistently. Under steady shear the deformation of the brush proceeds in two steps: chains tilt in t…
The synthesis, crystal structures, and magnetic properties of linear pentanuclear complexes, [Ni(5)(&mgr;(5)-tpda)(4)X(2)](n)()(+) [tpdaH(2) = tripyridyldiamine, with different axial ligands X = Cl(-) (1), CN(-) (2), N(3)(-) (3), and NCS(-) (4) (n = 0) and CH(3)CN (5) (n = 2)], are reported. All of the [Ni(5)(tpda)(4)…
We report the synthesis of high molecular weight triblock copolymers of the type ABA and BAB, where A is polyisoprene (PI) and B is poly(pentamethyldisilylstyrene) (P(PMDSS)), respectively. The volume fraction of the minority component (PI) for the ABA copolymer was 0.33, while that for the BAB copolymer was 0.23. The…
The results of a recent neutron diffraction experiment on water confined in Vycor glass, reported in the preceding paper [F. Bruni, M. A. Ricci, and A. K. Soper, J. Chem. Phys. 109, 1478 (1998)], are analyzed by attempting to correct for the distortions brought into the site–site radial distribution functions by the p…
The synthesis of zirconium oxide with a mesostructured framework (Zr-TMS) has been achieved through the use of amphiphilic compounds with a variety of headgroups (anionic and nonionic) and tail group chain lengths (1−18 carbons). Anionic surfactants with phosphate, carboxylate, sulfate, and sulfonate headgroups led to…
Polarized laser Raman microscopy was employed in order to investigate the effects of side chain length on the orientability of uniaxially drawn films of a model hairy-rod polymer, as a function of draw ratio; an aromatic polyester containing terphenyl units in the main chain and aliphatic side chains (hexyl and dodecy…
We examined polymer conformations at a strongly adsorbing solid surface and their evolution with elapsed time during the adsorption process. Poly(dimethylsiloxane) (PDMS: M w = 118 000; M w / M n = 1.16) was allowed to adsorb onto oxidized germanium from dilute carbon tetrachloride solutions. The mean backbone orienta…
The properties of elastomeric polypropylene synthesized from an unbridged metallocene catalyst are investigated by mechanical rheometry, differential scanning calorimetry, and optical depolarization. The material is compositionally heterogeneous in tacticity, and its behavior is compared to that of its solvent fractio…
Free-standing polyaniline films are studied as pervaporation membranes for separating carboxylic acid/water mixtures. Changing polyaniline membranes from an undoped to a fully doped state has a dramatic effect on their selectivity. For example, with a 52 wt % acetic acid/48 wt % water feed, the undoped, base form of p…
Contrast in MRI relies on differences in the local environment of water and is often enhanced by using contrast agents. We present a simple model for evaluating the minimal contrast agent concentration required to produce "satisfactory" contrast enhancement in magnetic resonance images. Previous strategies have been b…