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Abstract If the collagen triple helix is so built as to have one set of NH ⃛ O hydrogen bonds of the type N 3 H 3 (A) ⃛ O 2 (B), then it is possible to have a linkage between N 1 H 1 (B) and O 1 (A) through the intermediary of a water molecule with an oxygen O leading to the formation of the hydrogen bonds N 1 (B) ⃛ O…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRaman spectroscopy of sulfur, sulfur-selenium, and sulfur-arsenic mixturesAnthony T. WardCite this: J. Phys. Chem. 1968, 72, 12, 4133–4139Publication Date (Print):November 1, 1968Publication History Published online1 May 2002Published inissue 1 November 1968https://pubs.acs.…
Abstract By making use of the vapor-condensation type calorimeter, the heat capacity measurements of amorphous, cubic and hexagonal ices were made between 20°K and 250°K. The glass transition phenomenon was found near 135°K with the sudden change of the heat capacity amounting to 35 J/(mol°K). The drastic crystallizat…
Anomalies found in the intensity of $p$-polarized light from concave diffraction gratings have been analyzed in terms of an interaction between the incoming photon and a surface-plasmon resonance in the grating surface. There is clear evidence for zone gaps in the dispersion curves which we have constructed for surfac…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReaction of hydrogen with alloys of magnesium and nickel and the formation of Mg2NiH4James J. Reilly Jr. and Richard H. Wiswall Jr.Cite this: Inorg. Chem. 1968, 7, 11, 2254–2256Publication Date (Print):November 1, 1968Publication History Published online1 May 2002Published i…
An optical emission process is observed in which a ${\mathrm{Cr}}^{3+}$ ion, initially in the $^{2}E_{\mathrm{g}}$ excited state, simultaneously emits a photon and excites a neighboring ${\mathrm{Eu}}^{3+}$ ion to an excited $^{7}F_{J}$ level. Transitions terminating on $J=1$ through 5 have been found.
The Brillouin-scattering spectrum of K${\mathrm{H}}_{2}$P${\mathrm{O}}_{4}$ has been studied over the temperature range $118\ifmmode^\circ\else\textdegree\fi{}\mathrm{K}<T<300\ifmmode^\circ\else\textdegree\fi{}\mathrm{K}$ with particular emphasis on the region close to the ferroelectric transition at 122\ifmmode…
We introduce a simple model Hamiltonian for the study of phase transitions in perovskite compounds $\mathrm{AB}{\mathrm{O}}_{3}$ involving rotations of $B{\mathrm{O}}_{6}$ octahedra. Depending on the relative magnitude of the anharmonic coefficients, we find a transition to the tetragonal or to the trigonal phase. We…
The electrical resistivity was determined for polycrystalline and single-crystal BeO between 1200°–1700°C. Analysis was made of the effects of oxygen partial pressure, aliovalent impurities, and microstructure. Conductivity and relevant diffusion coefficients were calculated with these data. The results show the BeO s…
The heat capacity of a single crystal of CaWO4 was determined by adiabatic calorimetry from 5° to 350°K and found to be without transitions or thermal anomalies. Deviation of the curve from normal sigmate shape is shown to be due to internal vibrations of the WO4= ions. Apparent Debye θ's for the lattice-only heat cap…
Abstract Single, double and multi-layered dislocation loops have been observed in thin foils of quenched magnesium, and the structure of the loops established by contrast analysis. On annealing in the temperature range 150 to 200°C the loops are observed to grow as a result of the production of vacancies by surface ox…
A series of Ni(II) complexes with methyl-, ethyl-, and sym-dimethyl-, sym-diethyl-, and sym-di-n-butyl- thioureas and halide, perchlorate, and thiocyanate anions have been prepared and characterized. Spectral and magnetic studies show that compounds NiL 4 X 2 (L = N,N′-dimethyl and N,N′-diethylthiourea, X = halide) ar…
The viscosity measurements on 1,3,5-tri-α-naphthylbenzene have been extended to 407°C, in order to establish the limiting high-temperature Arrhenius activation energy. Diverse functions have been used to fit the viscosity results on this material which range over 15 orders of magnitude. From the temperature dependence…
The structure of thiourea nitrate has been determined by three-dimensional X-ray methods. Both Cu Ke and Mo K~ data were obtained with a single-crystal diffractometer and the final R values are 4.9% and 5.5% respectively. The space group is P211m and there are two molecules in the unit cell. All atoms, including hydro…
The ${F}^{\ensuremath{'}}$ band has been produced and measured in the following alkali halides: NaCl, KCl, KBr, KI, RbCl, RbI, CsBr, and CsI. Additively colored samples were optically bleached in the $F$ band at an optimum temperature to produce a maximum $F$-to-${F}^{\ensuremath{'}}$ conversion. The observed spectra…
Polarized far-infrared spectra of aliphatic polyesters [–(CH2)z–CO–O–O]n with z = 1, 2, and 5 (z = 4, nonpolarized) and α-polyamide (nylon 6 and its N-deuteroderivative) have been measured in the region up to 80 cm−1. All these polymers have essentially planar zigzag conformations. The normal vibrations of these polym…
Measurements of the 57Fe Mössbauer spectrum of phthalocyanine iron(II) made at 4.2° and 100°K, with the sample in applied magnetic fields of 30 kOe, show that the electric field gradient at the iron nucleus is of positive sign and that there is no large asymmetry in the electric-field-gradient tensor. The major axis o…
The reflectivity of single-crystal sodium nitrite has been measured as a function of temperature and crystallographic orientation over a wavelength region which spans all the eight infrared-active normal modes. The temperature-dependent dielectric response functions and oscillator parameters have been obtained both by…
Photoluminescence studies were made at liquid-helium temperatures of epitaxial GaAs with ionized-impurity concentrations \ensuremath{\lesssim}${10}^{15}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. Narrow linewidths at half-height were achieved by using material of high purity and perfection, by using low intensities of illumi…
Crystals of ${\mathrm{Ti}}_{2}$${\mathrm{O}}_{3}$ of relatively high purity or doped with various impurities have been grown by the Czochralski method. The semiconductor-metal transition commenced at 435\ifmmode^\circ\else\textdegree\fi{}K with a change of resistivity from 9\ifmmode\times\else\texttimes\fi{}${10}^{\en…