Materials Literature
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ABSTRACT The Greater Yellowstone Area ecosystem experienced major wildfires in 1988, resulting in a substantial number of catchments being burned. We studied diatom assemblage structure at 14 sites over 5 years in catchments ranging from 0 to over 90% burned. Coefficients of variation for selected physical measures pr…
Abstract The sequential reaction of selected polycyclic aromatic hydrocarbons with butyllithium/TMEDA/hexane and sulfur allows preparation of ring‐fused dithiins, dithioles, and thiophenes. In this manner, phenanthrene has been converted to phenanthro[4,5‐cde][1,2]dithiin and phenanthro[1,10cd]‐1,2‐dithiole. Yellow cr…
The geometric moisture diffusivity model developed by this research indicates that fiber volume fraction and shape coefficient are the most important structural parameters affecting water vapor diffusivity through nonhydrophilic nonwoven fabrics. Water vapor diffusivity decreases with increasing fiber volume fraction…
Abstract The thermal degradation processes which occur in poly(ether‐sulfone) (PES) and poly(phenylene oxide) (PPO) have been studied by Direct Pyrolysis‐Mass Spectrometry (DPMS). The pyrolysis mass spectra of PES and PPO contain molecular ions up to m/z 700, corresponding to pyrolysis compounds of sufficient size to…
Abstract The reaction between 4,5( E )‐epoxy‐2( E )‐heptenal (EH) and l ‐lysine was studied to characterize some of the compounds that may be produced when proteins react with peroxidizing lipids. A mixture of EH and lysine was incubated overnight at room temperature and then fractionated by high‐performance liquid ch…
Results of X-ray and ellipsometric studies on self-assembled monolayer films of three fluorinated chlorosilanes are presented. By inferring an index of refraction, the monolayer thicknesses obtained from both these types of studies are self-consistent. The tilt of the molecules with respect to the layer normal is foun…
The gas phase thermal decomposition rates of the C1 and C2-substituted peroxyacyl nitrates (RC(O)OONO2), PAN (R = CH3), PPN (R = C2H5) and vinyl-PAN (R = CH2 = CH-) have been measured at ambient temperature (288 - 299 K) and 1 atm. of air. Our results for PAN (k = A exp (-Ea/RT), log10 (A, s-1) = 16.2 ± 1.6, Ea = 26.9…
The morphology of the polished surfaces of semiconducting diamonds has been examined by scanning tunnelling microscopy. The faces polished along a direction of difficult abrasion show a rough structure which indicates that material was removed by fracture and chipping on a nanometre scale. The faces polished along a d…
Single crystals of the linear chain phase ${\mathrm{Nd}}_{2}$${\mathrm{BaNiO}}_{5+\mathrm{\ensuremath{\delta}}}$ [\ensuremath{\delta}=0.005(1)] have been prepared and the magnetism studied by neutron scattering. The Ni-O chain direction is along the short axis a. Long-range antiferromagnetic order sets in below ${\mat…
The oxidation behavior of a sintered aluminum nitride containing 3 wt% Y 2 O 3 as a sintering aid was investigated. Samples were exposed to air at elevated temperatures for times up to 100 h. The weights of the samples were continuously monitored during exposure at various temperatures and humidity levels. The effects…
Abstract In studies on the fate of aluminium in the environment, nontronite and saponite have been obtained by synthesis in reducing alkaline conditions close to those prevailing in poorly drained soils developed from limestones. The two minerals obtained have different structures and organizations corresponding to tw…
Microscopic studies at different scales have shown that in biological tissues the three-dimensional arrangement of chitin-protein or of collagen fibrillar networks can follow the same spatial distributions as those described in certain liquid crystals. The present work reviews the structural analogies established betw…
Electrochromic tungsten trioxide thin films were prepared by chemical vapor deposition. The source material was tungsten carbonyl. Amorphous tungsten trioxide thin films were obtained at a substrate temperature of 300°C. Reduction and oxidation of the films in a 0.3 M propylene carbonate solution resulted in desirable…
Polyaniline, poly(ethylene oxide), poly(propylene glycol), poly-(vinylpyrrolidinone), methyl cellulose, polyethylenimine, polyethylene, and Nylon-6, were encapsulated into MoS2. Electrical conductivity and thermoelectric power measurements of pressed pellets of (PEO)0.92MoS2 and (Polyaniline)0.35MoS2 show p-type metal…
Mixtures of alumina and silica react with SiF 4 above 600°C to form fluorotopaz. Pyrolysis of fluorotopaz gives a stoichiometric yield of interlocked whiskers of mullite and SiF 4 , which is recovered for reuse. The diameter of whiskers (aspect ratio ∼15) can be controlled from a maximum of ∼100 μm to less than 1 μm.
We studied the electrodynamic response of α-(BEDT-TTF)2I3 in a wide range of frequency, covering microwave and millimeter wave frequencies as well as the optical spectral range, and found a frequency dependent conductivity up to 1000 cm-1 in the low temperature phase. This is accompanied be a non-linear transport with…
The solid-phase chemical synthesis of ubiquitin produced a molecule with physicochemical properties similar to those of the natural protein. We have grown crystals of this synthetic ubiquitin and performed an X-ray analysis at 1.8 A resolution in order to compare the synthetic protein with the known natural structure.…
Nickel-catalyzed polymerization which employs the coupling of isomeric dichlorobenzophenones is described. The polymerization utilizes inexpensive readily available monomers, 4,4'-dichlorobenzophenone (4,4'-DCBP) and 2,5-dichlorobenzophenone (2,5-DCBP). The poly(4,4'-benzophenone) can be derivatized to be soluble duri…
The decomposition of a duplex stainless steel during aging at 600°C has been investigated using analytical transmission electron microscopy with the intention of elucidating the nucleation sites of the new phases arising from ferrite decomposition. The first transformation product to be formed is M23C6. This carbide,…
Three-dimensional electron diffraction intensity data from form (III) of isotactic poly(1-butene) have been collected by tilting solution- and epitaxially grown thin microcrystals. The orthorhombic space group is P2 1 2 1 2 1 with cell constants a= 12.38, b= 8.88 and c= 7.56 A, the latter being the chain repeat. The c…