Materials Literature
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During rapid growth, the excretion of pyrimidines, predominantly uracil, is a common phenomenon in procaryotes and eucaryotes. In Escherichia coli, some K-12 strains excrete orotic acid and not uracil. This is caused by a mutation in the pyrF gene.
The infrared absorption and laser Raman spectra of BaCl 2 ·2H 2 O powder and single crystals as well as BaCl 2 ·2D 2 O, partially deuterated, and isotopically dilute samples have been analyzed in the range from 30 to 4000 cm −1 . A revised interpretation of the observed water bands is given. The influence of the bond…
Ordinarily one expects the structural and magnetic properties of a given substance to be intimately related, with the dimensionality of the magnetic or electrical interactions that are present reflecting the lattice dimensionality. For example, a cluster of two interacting magnetic ions should obey a theoretical model…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrgano-substituted phosphazenes. 10. Reactions of hexafluorocyclotriphosphazene with propenyllithium reagentsJohn G. DuPont and Christopher W. AllenCite this: Inorg. Chem. 1978, 17, 11, 3093–3096Publication Date (Print):November 1, 1978Publication History Published online1 M…
Raman spectroscopy has been applied to the study of the pH-dependent decomposition of 12-molybdophosphoric acid, H 3 (PMo 12 O 40 ), and 12-molybdosilicic acid, H 4 (SiMo 12 O 40 ), in aqueous solution. The decomposition schemes involving several smaller polymeric molybdate species, proposed from indirect techniques s…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLanthanide photochemistry initiated in f-f transitionsTerence DonohueCite this: J. Am. Chem. Soc. 1978, 100, 23, 7411–7413Publication Date (Print):November 1, 1978Publication History Published online1 May 2002Published inissue 1 November 1978https://pubs.acs.org/doi/10.1021/…
Marine atmosphere and synthetic sea water stress corrosion tests on smooth and precracked specimens from 7075, 7050, and 7049 alloy plates (32 and 76 mm thick) show that for a given strength level, alloys 7050-T7X and 7049-T7X have superior short-transverse stress corrosion resistance (SCR) to 7075-T7X. At typical str…
Abstract An effective vulcanization recipe for tetrafluoroethylene-propylene elastomer was searched for and the following results were obtained: (1) The C 2 F 4 -C 3 H 6 copolymer is susceptible only to peroxide and is not crosslinked at all by other reagents. (2) The peroxide vulcanization is greatly accelerated by s…
Measurements are reported to determine the average energy W expended to form an ion pair in air for incident electrons in the energy range from 30 eV to 5 keV. For energies T greater than or equal to 60 eV the standard deviations are lower than 1%. In addition, backscatter coefficients R/sub i/ with respect to the spa…
Flashovers have occurred in Europe on quite lightly polluted insulators, both under heavy rain and during the operation of live-washing systems. To avoid such flashovers a new device, the booster shed, has been developed.
Abstract The chemorheology of polymers prepared by peroxide curing terpolymers of ethylene propylene and diene monomer (EPDM) was studied at 375°F in air. Measurements were conducted on terpolymers containing dicyclopentadiene (DCPD), ethylidene norbornene (ENB) or 1,4‐hexadiene (HD) and also on copolymers. Effects of…
A Fourier-transform method is used to obtain the displacement field for an edge dislocation. The method reproduces known results and produces new solutions that can be compared with those from atomistic models of edge dislocations.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotophysical studies on benzil. Time resolution of the prompt and delayed emissions and a photokinetic study indicating deactivation of the triplet by reversible exciplex formationTai-Shan Fang, Ronald E. Brown, Chi Lup Kwan, and Lawrence A. SingerCite this: J. Phys. Chem.…
Abstract PVC made by suspension and anionic polymerization was partially dehydrochlorinated by three different methods. In the first one, a solution in THF and in the second one, particles swollen by dioxane were treated with alcoholic KOH at low temperatures. In the third method, a solution of PVC in DMF was heated t…
Kinetic theories of crystallization of polymers do not apply to high supercooling. The thickness of the crystalline lamellae becomes independent of the crystallization temperature and is a characteristic parameter of the polymer. We relate this limiting thickness to the flexibility of the polymer chain in the pure liq…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal and molecular structure of trimeric bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)dioxouranium(VI)J. C. Taylor, A. Ekstrom, and C. H. RandallCite this: Inorg. Chem. 1978, 17, 11, 3285–3289Publication Date (Print):November 1, 1978Publication History Published online1…
Of the two formulas previously reported for the compound on the alumina‐rich side of the system La 2 O 3 ‐Al 2 O 3 , present experimental results indicate that LaAl 11 O 18 is correct. This compound melts congruently at ∼2000°C and has a hexagonal structure with lattice parameters of a 0 = 5.561± 0.007 Å and c 0 =22.0…
The line groups are the symmetry groups of stereoregular polymer molecules. For quantum mechanical applications one needs their unitary irreducible representations (reps). All the reps of the line groups whose isogonal point groups are C n , C nv , C nh , S 2n , and D n are constructed. For some line groups the reps a…
High-resolution ac microcalorimetry studies of octyloxycyanobiphenyl, 80CB, reveal a nematic-smetic-$A$ transition consistent with the superfluid analogy as regards the specific-heat exponents, namely $\ensuremath{\alpha}={\ensuremath{\alpha}}^{\ensuremath{'}}\ensuremath{\lesssim}O(log)$. However, the amplitude ratio,…
Stress intensity factors are estimated for three‐dimensional defects which occur in ceramic bodies. The two idealized cases considered are a spherical void with a circumferential crack at its equator stressed by uniaxial tension at infinity and a hemispherical pit at a free surface of a semi‐infinite body also stresse…