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The energetics of nickel clusters over a broad size range are explored within the context of the many-body potentials obtained via the embedded atom method. Unconstrained local minimum energy configurations are found for single crystal clusters consisting of various truncations of the cube or octahedron, with and with…
The glass-transition temperatures, Tg, of organic liquids confined to small pores were studied by differential scanning calorimetry (DSC). The Tg was measured as a function of pore size in controlled pore glasses (CPG) having pore diameters in the range of 40–730 Å. The surface of the glass was treated with hexamethyl…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOne-step synthesis of hyperbranched dendritic polyestersC. J. Hawker, R. Lee, and J. M. J. FrechetCite this: J. Am. Chem. Soc. 1991, 113, 12, 4583–4588Publication Date (Print):June 1, 1991Publication History Published online1 May 2002Published inissue 1 June 1991https://pubs…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHydrophobic effects on simple organic reactions in waterRonald BreslowCite this: Acc. Chem. Res. 1991, 24, 6, 159–164Publication Date (Print):June 1, 1991Publication History Published online1 May 2002Published inissue 1 June 1991https://pubs.acs.org/doi/10.1021/ar00006a001ht…
The storage of electrochemical energy in battery, "supercapacitor," and double‐layer capacitor devices is considered. A comparison of the mechanisms and performance of such systems enables their essential features to be recognized and distinguished, and the conditions for transition between supercapacitor and "battery…
Stereochemical studies of three pyridoxal phosphate dependent decarboxylases and serine hydroxymethyltransferase have allowed the dispositions of conjugate acids that operate at the C alpha and C-4' positions of intermediate quinoids to be determined. Kinetic work with the decarboxylase group has determined that two d…
Analysis of the mechanism and structure of lactate dehydrogenases is summarized in a map of the catalytic pathway. Chemical probes, single tryptophan residues inserted at specific sites and a crystal structure reveal slow movements of the protein framework that discriminate between closely related small substrates. On…
The determination of three separate gamma-chymotrypsin structures at different temperatures and resolutions confirmed the presence of electron density in the active site, which could be interpreted as an oligopeptide as had previously been suggested by Dixon and Matthews [(1989) Biochemistry 28, 7033-7038]. HPLC analy…
Low-temperature phase transitions and twin-domain structure of (NH4)3H(SeO4)2 studied by the electron paramagnetic resonance of Cu2+, VO2+ and SeO3-, Wu Ching-Jiun, Yu Jiang-Tsu, Tsai Mei-Na, Lou Ssu-Hao
Raman scattering was used to study optical phonons in a Si12Ge4 strained-layer superlattice on c-Si(001) that was subjected to hydrostatic pressure at room temperature. The change of phonon frequency with pressure, dω/dP, for the principal quasi-confined LO mode in the Ge layers, is found to be significantly smaller t…
The anisotropic thermal conductivity of ${\mathrm{Al}}_{65}$${\mathrm{Ni}}_{20}$${\mathrm{Co}}_{15}$ and ${\mathrm{Al}}_{62}$${\mathrm{Si}}_{3}$${\mathrm{Cu}}_{20}$${\mathrm{Co}}_{15}$ single quasicrystals has been measured. While a nearly isotropic phonon contribution was observed, the electronic thermal conductivity…
For pt. I see ibid., vol.3, p.1915 (1991). The paper reports spectroscopic studies of Cr 3+ ions in fluorozirconate. fluoride, borate and telluride glasses in which the average strength of the octahedral crystal field Dq/B varies from 1.6 to 2.4. The emission spectra are shown to be inhomogeneously broadened by disord…
We present molecular-dynamics computer-simulation studies of 25-keV displacement cascades in Cu at low temperature. We observe the splitting of a cascade into subcascades and for the first time show by molecular dynamics that cascades in metals may lead to the formation of both vacancy and interstitial dislocation loo…
Ultrathin films of simple nonpolar molecular fluids (3--8 segmental dimensions thick) show a strikingly long relaxation time in response to oscillatory shear when confined between mica plates at 27 \ifmmode^\circ\else\textdegree\fi{}C. When the shear rate exceeds this inverse time, the effective viscosity decays as an…
We report the first application of valence-band photoemission to a quantum-dot system. Photoemission spectra of cadmium sulfide quantum dots, ranging in size from 12 to 35 \AA{} radius, were obtained using photon energies of 20 to 70 eV. The spectra are qualitatively similar to those obtained for bulk cadmium sulfide,…
Enormous impact pressures can develop when a vapor cavity collapses in a liquid, and it is generally held that these pressures are the underlying cause of cavitation damage of surfaces. The rapid growth and disappearance of vapor cavities have been viewed with a surface forces apparatus in liquids, and their effects o…
Studies of the chemistry that occurs on the nanosurfaces of size-selected silicon clusters reveal a number of fascinating qualitative similarities to the behavior of bulk surfaces. However, silicon clusters containing up to 70 atoms appear to be much less reactive than bulk silicon surfaces. This unexpected result sug…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIn situ quantitation of protein adsorption density by integrated optical waveguide attenuated total reflection spectrometryS. S. Saavedra and W. M. ReichertCite this: Langmuir 1991, 7, 5, 995–999Publication Date (Print):May 22, 1991Publication History Published online1 May 2…
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Abstract Tetrafluoroethylene (TFE) was copolymerized with 1‐fluorosulfonyl‐difluoroacetylfluoride (FSDFAF) in both the bulk and solution by using a free radical initiator at temperature 50°C. The presence of sulfonyl fluoride (SO 2 F) functional groups in the copolymers was proved by infrared (IR) spectroscopy. The c…