Materials Literature
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Abstract Ultradrawing of films of high‐molecular‐weight polyethylene (M̄ w = 1.5 × 10 6 ) produced by gelation crystallization from solution is discussed. The influence of the initial polymer volume fraction (ϕ) on the maximum draw ratio (λ max ) of the dried films is examined in the temperature region from 90–130°C.…
Two-dimensional NMR techniques which sep. the chem. shift and heteronuclear dipolar interactions were applied to samples spinning at the magic angle. Because of the inhomogeneous nature of the 2 interactions, rotational echoes were obsd. in the time domain of each dimension. The corresponding Fourier transforms yield…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDegree of charge transfer in organic conductors by infrared absorption spectroscopyJ. S. Chappell, A. N. Bloch, W. A. Bryden, M. Maxfield, T. O. Poehler, and D. O. CowanCite this: J. Am. Chem. Soc. 1981, 103, 9, 2442–2443Publication Date (Print):May 1, 1981Publication Histor…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHigh-valent iron-porphyrin complexes related to peroxidase and cytochrome P-450John T. Groves, Robert C. Haushalter, Mikio Nakamura, Thomas E. Nemo, and B. J. EvansCite this: J. Am. Chem. Soc. 1981, 103, 10, 2884–2886Publication Date (Print):May 1, 1981Publication History Pu…
The satellite structure of core photoelectron and Auger lines of the copper dihalides are explained in terms of final-state energies diminished by Coulomb interactions between the valence electrons and the created core hole or holes. The satellite structure in the $3p$ and valence-band photoelectron spectra are shown…
A noncytotoxic dose of verapamil, a coronary vasodilator, enhances the cytotoxicity of vincristine (VCR) and vinblastine in P388 leukemia and its VCR-resistant subline, P388/VCR. When 2.2 to 6.6 microM verapamil was added along the VCR to the P388/VCR culture in vitro, VCR resistance was completely overcome. Verapamil…
An experiment is described in which a synthetic diamond containing a high concentration of dispersed nitrogen atoms was heated at 2400 degrees C and 2500 degrees C under a stabilising pressure of about 9.5 GPa. The nitrogen atoms aggregated to form the types of nitrogen centres which are found in natural type 1a diamo…
The thermal conductivity and specific heat of epoxy-resin samples made from Epikote 828 resin wth Epikure NMA hardener has been measured from 0.1 to 80K. The samples were produced under various curing conditions. Normally-cured samples (Cure N)-2 h at 100 degrees C followed by 4 h at 200 degrees C; cure A-36 h at 66 d…
For pt.I see ibid., vol.12, p.5393 (1979). A programme of elastic neutron-diffraction experiments has been undertaken to derive (and compare) atomic distribution functions, with high spatial resolution, for the ABX 3 antiferroelectric perovskites SrTiO 3 , KMnF 3 , RbCaF 3 and CsPbCl 3 in their cubic phase. The backgr…
The model of human Fc fragment was refined at 2.9-A resolution. Two different automated procedures for crystallographic refinement were used [Deisenhofer, J., & Steigemann, W. (1975) Acta Crystallogr., Sec. B B31, 238; Jack, A., & Levitt, M. (1978) Acta Crystallogr., Sect. A A34, 931]. The final R value is 0.22. The d…
Polarized reflectance measurements from the far infrared to the visible are reported for ${(\mathrm{TMTSF})}_{2}$P${\mathrm{F}}_{6}$. At low temperatures, both parallel and perpendicular polarizations show plasma edges in the infrared with metallic reflection below these edges, indicating two- or three-dimensional beh…
Structural phase transitions in K 2 CO 3 have been investigated using light scattering techniques. The Raman spectrum of the high-temperature hexagonal phase consists of a very broad structureless band which suggests that the system is highly anharmonic. Below the hexagonal-monoclinic transition at T cl =693K the auth…
Powdered and single crystal specimens of dysprosium manganate, DyMn 2 O 5 , have been studied by neutron diffraction at temperatures between ambient and 4.2K. Magnetic transitions are observed at 44K, 18K and 8.4K. Both manganese and dysprosium moments are ordered below 8.4K, where the magnetic structure has been refi…
Standard x-ray diffraction in which a reflection goemetry is used is shown to have a simple interpretation and adequate sensitivity for determining the structure of monolayers. It has been utilized to verify that subsurface strain occurs in Ge(001)-(2\ifmmode\times\else\texttimes\fi{}1) reconstruction.
The luminescence properties of yttrium niobate are reported. Two emission bands are observed, one in the blue and the other in the yellow spectral region. Decay measurements on the blue emission, which is the intrinsic niobate luminescence, provide evidence that this luminescence cannot be described with a tetrahedral…
The refractive index of pure and GeO2-doped silica glasses was measured at wavelengths from 0.4 μm to 2.1 μm, over a temperature range from 20°C to 540°C. Values for the thermal coefficient of the refractive index (about 1.2×10−5/°C at 1.3 μm) were almost identical for both glasses. The data showed that material dispe…
The production of significant concentrations of O(3P) in the gas phase reaction of hydrogen atoms with ozone in a fast flow discharge system at 1.1±0.1 Torr total pressure in Ar and at room temperature has been reported earlier. These yields were observed to be independent of the concentration of known deactivators of…
Ground state oxygen atoms, generated by visible photolysis of ozone, have been reacted with CH3SCH3 and CH3SH in argon matrices. For CH3SCH3, a stepwise addition to form DMSO and dimethylsulfone was observed. Methanethiol reactions with O atoms were more complex, leading to production of CH3SOH, CH3OSH, CH3S(O)H, and…
$3d$ core-level x-ray photoelectron spectrum (XPS) of Eu in Eu${\mathrm{Cu}}_{2}$${\mathrm{Si}}_{2}$ exhibits two sets of simple spin-orbit split structures. We have assigned these structures to two different valence states of Eu (${\mathrm{Eu}}^{2+}$ and ${\mathrm{Eu}}^{3+}$) in Eu${\mathrm{Cu}}_{2}$${\mathrm{Si}}_{2…
The elastic structure factor of an unpinned charge-density wave (CDW) is derived. Both phase and amplitude excitations are studied. Phase modes cause a reduction of the intensity of CDW satellite peaks of any order. Amplitude modes, however, do not alter appreciably the intensity of the first-order CDW satellite. In f…