Materials Literature
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The Raman spectra of carbon nanotubes prepared by catalytic (C-CNT) and d.c. arc discharge (D-CNT) methods are reported. A previously unnoticed third-order Raman peak at ca. 4248 cm-1 was observed in the Raman spectrum of D-CNT. The Raman features of D-CNT and C-CNT are similar to those of highly oriented pyrolytic gr…
UDP-galactose 4-epimerase from Escherichia coli catalyzes the interconversion of UDP-galactose and UDP-glucose through the transient reduction of the tightly bound cofactor NAD+. The enzyme is unique among the NAD+-dependent enzymes in that it promotes stereospecific reduction of the cofactor but nonstereospecific hyd…
Adsorption of water on M41s systems has been studied by means of microcalorimetry and IR spectroscopy. After thermal treatment at only 423 K, the samples show two types of surface patches, one hydrophobic (characterized by isolated silanols not interacting with water) and the other highly hydrophilic (showing the high…
Abstract It is known that PO 4 is retained by soils through ligand exchange, i.e., inner sphere complexation, but the mechanism for SO 4 adsorption at the mineral‐water interface has been in debate. By studying the effects of ionic strength on ion adsorption, it is possible to distinguish between inner and outer spher…
The electronic structure of a cobalt iron cyanide thin film, Na 0.4 Co 1.3 [Fe(CN) 6 ]5H 2 O, was switched from Fe III (low spin)−CN−Co II (high spin) to Fe II (low spin)−CN−Co III (low spin) by exchanging cations in interstitial sites from Na + to K + . The reverse process was also induced by replacing Na + with K +…
Dendritic mesogens—dendrimers that form mesophases —are the third group of liquid crystalline polymers (LCPs), following main‐chain and side‐chain LCPs. The synthesis of a series of different generations of dendromesogens (see Figure) is reported and their thermal behavior, molecular shape, and the textures observed b…
The ionic current‐overpotential characteristics of cathodes on ceria‐based electrolytes have been evaluated by galvanostatic current‐interrupt measurements. The measurements were carried out on mixed conducting ceria electrolytes under fuel cell operating conditions. The effect on the oxygen reduction kinetics of the…
It is the objective of this series of articles, beginning in this issue, to review for users the benefits of polymer insulating materials. Material science, design, and processing conditions all influence performance and must be considered. Using silicone as an example, we will discuss performance considerations and p…
The effect of molecular water on proton conduction was quantitatively analyzed from conductivity measurements of silica glasses with and without water molecules. The activation energy for conduction linearly decreased with increasing logarithm of proton concentration for glasses containing only protons as charge carri…
In industrial applications, a steady-state glow discharge capable of operating at one atmosphere would allow many plasma-related surface modification processes to be done on the production line, rather than in expensive vacuum systems that force batch processing. In this paper, we report some encouraging results from…
This paper describes the use of surface plasmon resonance (SPR) spectroscopy to measure the rates and extents of association of four detergents sodium dodecyl sulfate (SDS), β-octyl glucoside, Triton X-100, and Tween 20 to self-assembled monolayers (SAMs) of alkanethiolates on gold. SAMs presenting hexaethylene glycol…
A series of novel polymers have been prepared by free radical solution polymerization of a variety of hydrocarbon monomers with the (perfluoroalkyl)ethyl methacrylate monomer H 2 C C(CH 3 )CO 2 (CH 2 ) 2 (CF 2 ) n F, 1 ( n̄ ≈ 7.7). Polymers prepared using two different methods of feeding 1 into the reaction mass are d…
We discuss examples of designs for all-dielectric reflection gratings that tolerate high intensity and are potentially capable of placing up to 99% of the incident light into a single diffraction order, such as are needed for contemporary high-power lasers utilizing chirped-pulse amplification. The designs are based o…
(111) textured Au films were oxidized under UHV conditions by exposing them to UV radiation and ozone. The Au films were characterized by x-ray photoelectron spectroscopy. The gold surface becomes heterogeneous upon oxidation: approximately 0.8 monolayer (ML) of the adsorbed oxygen is present as chemisorbed species. T…
We examine the shear flow of hexadecane confined between plates with separation of 1–10 nm using molecular dynamics simulations. We also performed non-equilibrium molecular dynamics (NEMD) simulations of bulk hexadecane to compare with the simulations in the confined geometry. The stiffness of hexadecane and its high…
We consider the effects of Coulomb interactions on single-wall carbon nanotubes using an on-site Hubbard interaction, u. For the (N,N) armchair tubes the low-energy theory is shown to be identical to a two-chain Hubbard model at half-filling, with an effective interaction ${\mathrm{u}}_{\mathrm{N}}$=u/N. Umklapp scatt…
Thermoplastic poly(ester−urethanes) were polymerized in a two-step process: a condensation copolymerization of lactic acid (LA) and ε-caprolactone (CL), using stannous octoate as catalyst, followed by an increase in the molecular weight through urethane linking. The use of 1,4-butanediol results in oligomer molecules…
Transparent unplasticized zein films were prepared in aqueous ethanol or acetone. Tensile properties indicated that films prepared in acetone were stronger but less flexible than those prepared in ethanol. Both types of films, however, were too brittle for most applications. Films containing a glycerol:poly(propylene…
High-frequency planar magnetic components, employing thin film and thick film technology, have become important components in applications, such as filters and switching converters, due to their ease of manufacture and reliability. In a previous paper, the authors established a frequency dependent impedance formula fo…
Using a two-dimensional Scheutjens and Fleer self-consistent field calculation, we determine the equilibrium morphology of thin films of symmetric AB diblock copolymers confined between hard, smooth plates. A lamellar phase is established with the stripes either perpendicular or parallel to the walls. With neutral wal…