Materials Literature
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The Raman spectrum of dihydrofolate (H 2 folate) complexed with dihydrofolate reductase (DHFR) and NADP +, believed to be an accurate mimic of the productive DHFR/NADPH/H 2 folate complex involved in the reaction catalyzed by DHFR, contains bands associated with stretch motions of N5 C6 of bound substrate. However, th…
The mechanism of poly( p -phenylenebenzoxazole) formation from terephthalic acid (TA) and diaminodihydroxybenzene dihydrochloride (DADHB) in polyphosphoric acid (PPA) was studied. The solubility of TA in PPA with 86% P 2 O 5 content was determined to be 0.02% at 100 °C and 0.06% at 140 °C. Dissolved TA existed as thre…
The sequential reaction of (OEP)Os(CO) with NOPF 6 (in CH 2 Cl 2 ) followed by RMgX (in THF) gives variable isolated yields of the new (OEP)Os(NO)R (5−44%), (OEP)Os(R) 2 (1−10%), (OEP)Os(NO)X (14−19%), and [(OEP)Os(NO)] 2 (μ-O) (up to 24%) compounds, depending on the reaction conditions and the nature of R and X (OEP…
This paper reports a systematic experimental and theoretical study of the second-order nonlinear optical properties of multichromophoric molecules that range from dipolar symmetry to three-dimensional octupolar symmetry. The four possible conformers of tetranitrotetrapropoxycalix[4]arene ( cone, paco, 1,2-alt, 1,3-alt…
The degree of polymerization (DP n ) of poly( p -phenylene) (PPP) 3 with appendant third-generation, Fréchet-type dendrons was determined as 110 after a chemical modification. This DP n is extraordinarily high and shows that the mechanistically complex Suzuki polycondensation can thus be employed even in the case of s…
The effects of a metal ion-bound carboxylate group on the acidity of a water molecule bound to the same cation have been assessed by ab initio molecular orbital calculations. In the hexahydrate Mg[H 2 O] 6 2+ the free energy required to deprotonate one coordinated water molecule is only 40% of that required to deproto…
Forced Rayleigh scattering (FRS) and pulsed-field-gradient NMR have been used to measure the self-diffusion coefficient, D, of a poly(ethylene oxide)−poly(ethylethylene) diblock copolymer in the molten state. The copolymer contains 42% PEO by volume and has a total molecular weight of 4100 g/mol. Upon heating from roo…
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…