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A flowing afterglow−tandem mass spectrometer has been used to determine 0 K bond strengths in three hypervalent polyhalide ions: D (Cl 2 −Cl - ) = 99 ± 5 kJ/mol, D (Br 2 −Br - ) = 127 ± 7 kJ/mol, and D (Br 2 −Br 3 - ) = 40 ± 7 kJ/mol. These bond strengths are close to the previously measured values D (I 2 −I - ) = 126…
Neutron scattering, ac susceptibility, and NMR measurements have been made on isotopically enriched ${}^{154}{\mathrm{SmMn}}_{2}{\mathrm{Ge}}_{2}.$ All the magnetic states are characterized from much clearer neutron-diffraction spectra than in previous works, in which natural abundance Sm was used. A temperature versu…
The adsorption and reaction of CO on Rh particles supported on oxidized and partially reduced epitaxial ceria films on yttria-stabilized cubic zirconia (YSZ) (100), (110), and (111) single crystals was studied using temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). The ceria films on…
The effects of solution variations during growth on the perfection of tetragonal lysozyme crystals have been characterized using X-ray topography and high angular and wavevector resolution reciprocal-space scans. X-ray images of crystals grown under nearly uniform conditions show little contrast or evidence of defects…
The interactions of water with H−ZSM-5, Cu−ZSM-5, and Co−ZSM-5 have been investigated by density functional theory (DFT). Calculations were also performed to determine the thermodynamics of metal removal from the zeolite. For all three forms of ZSM-5, water adsorbs by direct interaction of the O atom with the cation a…
Biodegradable poly(lactic acid)-grafted amylose was synthesized using a trimethylsilyl (TMS) protection method. Tetrahydrofuran soluble, mostly trimethylsilyl protected amylose was prepared and reacted with potassium tert-butoxide to give the corresponding alkoxide. Poly(lactic acid)-grafted amyloses were obtained by…
It was shown that in the polymerization of 2-methyl-2-oxazoline initiated with benzyl bromide in nitrobenzene the equilibrium constant of the interconversion of cationic and covalent active centers could be measured over a wide range of temperatures, thus making the thermodynamic parameters of this reaction available.…
The expanded Hansen method was tested for determination of the solubility parameters of two non-steroidal anti-inflammatory drugs, naproxen and sodium diclofenac. This work describes for the first time the application of the method to the sodium salt of a drug. The original dependent variable of the expanded Hansen me…
Coprecipitates, Ni(OH)2 + 2Fe(OH3, were milled in a planetary mill, using an agate bowl and balls (99.9% SiO2), and then heated at a maximum temperature of 573 or 773 K. The Mossbauer spectra at 298 K of the ball-milled samples (not heated) showed the superposition of two quadrupole doublets. After heating at 573 K, t…
Using the Gibbs description of an interphase, the necessary conditions for equilibrium of a closed, two-phase fluid system in the presence of gravity are the Laplace and Young equations and a condition on the chemical potentials. The last condition has been neglected in all previous examinations of contact angles in a…
Supramolecular multilayered ferromagnets in which metal layers are interleaved with iminonitroxide benzoate radical anions have been synthesized and characterized by the authors. The structure of these novel compounds (see cover) consists of stacks of alternating organic–inorganic layers. Long-range ferromagnetism is…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Chemistry behind Carbonless Copy PaperMary Anne White View Author Information Dalhousie University, Department of Chemistry, Halifax, Nova Scotia B3H 4J3, CANADACite this: J. Chem. Educ. 1998, 75, 9, 1119Publication Date (Web):September 1, 1998Publication History Receive…
ESR measurements have been carried out on Mn ions in PbTiO 3 ceramics. Mn ions in the PbTiO 3 ceramics are incorporated at Ti 4+ sites with mixed valence states of Mn 2+ and Mn 4+ . The proportion of Mn 2+ ions is the highest for the calcined powder and changes during the firing process. After the firing it decreases…
The effect of OH bonds on the optical absorption and persistent spectral hole burning (PSHB) properties was quantitatively analyzed in ${\mathrm{Eu}}^{3+}$-doped $\mathrm{BaO}\ensuremath{-}{\mathrm{P}}_{2}{\mathrm{O}}_{5}$ glasses. Glasses were prepared by melting the raw material at 600--$800\ifmmode^\circ\else\textd…
We present an experimental investigation of the influence of interfacial anisotropy on the cellular growth patterns observed in directional solidification of the ${\mathrm{CBr}}_{4}\ensuremath{-}8\mathrm{}\mathrm{mol}%$ ${\mathrm{C}}_{2}{\mathrm{Cl}}_{6}$ alloy at pulling velocities less than twice the cellular-thresh…
Conductivity measurements were performed on bundles of single-walled carbon nanotubes with the aid of a scanning tunneling microscope (STM). Semimetallic current-voltage (I-V) characteristics generally indicated the bundles to be electronically similar to graphite. However, by moving the STM tip along the length of th…
Ab initio molecular orbital calculations on clusters of atoms consisting of various types of silica rings (3-, 4-, 5-, and/or 6-membered rings) that can be found in vitreous silica are performed at the Hartree-Fock (HF) level. We optimized the geometries of the clusters at the HF/6--31 G $(d)$ level; the average Si-O,…
A novel Brownian dynamics method has been developed to simulate the properties of polymer brushes under shear. Simulations of 100 chains with a chain length of 100 segments have been carried out for a range of shear rates. Compared to previous methods there is a substantial saving in computational time as the self-con…
New photolabile protecting groups have been found in the 2-(2-nitrophenyl)ethoxycarbonyl and the 2-(2-nitrophenyl)ethylsulfonyl group, respectively. The influence of substituents at the phenyl ring as well as the side-chain has been investigated regarding the photolysis rates on irradiation at 365 mn. β-Branching in t…
Abstract To explain the crystallization behaviour and phase relationships of precursor derived Si‐B‐C‐N ceramics, In ( p N 2 )‐ T diagrams were calculated. The results can be used to optimize the chemical composition and the physico‐chemical conditions for heat treatment. Stabilization of specific phase assemblages re…