During the last decade of a 37-year study of Downy Rattlesnake-plaintain (Goodyera pubescens (Willdenow) R. Brown) major herbivory by White-tailed Deer (Odocoileus virginianus) caused marked decreases in the sizes of two previously expanding populations. The 2012 drought resulted in an additional decline of one population. Because population growth depends on large flowerings, which occur only every four to eight years, recovery to 2002 levels would take several decades under favourable conditions.
Raman measurements of intermolecular vibrational frequencies, differential scanning calorimetry, and ESR measurements of triplet excitons are reported for crystalline anthracene–tracyanobenzene and various deuterated analogs. Deuteration of all the α- or all β-anthracene positions lowers the temperature of the order–disorder transition by 10–12 K. Perdeuteration lowers it by 17 K. The effect may result from decreased repulsive interactions when the CH bond is replaced by the shorter CD bond. High excitation light intensities can change the apparent transition temperatures and expand the measured coexistence range of the high- and low-temperature phases. (AIP)
The electron paramagnetic resonance of ${\mathrm{Mn}}^{2+}$ ions in powders and single crystals of PbTe and gadolinium-doped PbTe is reported. Resolved hyperfine and superhyperfine lines were measured from 4.2 to 120 K. The superhyperfine structure is attributed to the interaction between manganese ions and the tellurium ligands. At 4.2 K and 3330 G we obtain $g=1.994\ifmmode\pm\else\textpm\fi{}0.001$, ${a}_{\mathrm{Mn}}=65.7\ifmmode\pm\else\textpm\fi{}0.1 \mathrm{G} or (61.4\ifmmode\pm\else\textpm\fi{}0.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4} {\mathrm{cm}}^{\ensuremath{-}1}$ and ${a}_{\mathrm{Te}}=15.5\ifmmode\pm\else\textpm\fi{}1.0 or (14.5\ifmmode\pm\else\textpm\fi{}0.9)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4} {\mathrm{cm}}^{\ensuremath{-}1}$. The superhyperfine constant is temperature independent within experimental error.
Nitrogen-centered radicals produced by the action of Ag(0) or Ag(I)-amine systems on N-chloroazacyclononane, N-chloropiperidine, and N-chlorosuccinimide have been trapped using 2-methyl-2-nitrosopropane. The resulting nitroxides exhibited e.p.r. spectra consistent with structures 1, 2, and 3. Hydrogen gas evolved during reaction of the chloramines with Ag(0) was shown to arise completely from the amine derivatives.Excess Ag(0) reduced the succinamidyl radical to give the silver salt of succinimide.
William George Schneider OC FRS FRSC was an eminent Canadian chemist and science administrator. At the National Research Council of Canada (NRC) in Ottawa, he made high-precision measurements relating to the gas laws, to phase changes and to critical phenomena. He showed experimentally the need to reduce the gravitational density gradient in measurements of the critical point and used ultrasonic studies to support the concept of dynamic cluster formation. After a decade, he switched to nuclear magnetic resonance. He did pioneering work on the analysis of high-resolution spectra of protons in organic compounds and on the information that can be derived about intramolecular and intermolecular interactions. These studies were the basis for an influential book, High-resolution nuclear magnetic resonance , written with Harold Bernstein and John Pople. Concurrently, he investigated the photoconductivity and semiconductivity of insulating organic crystals, in particular anthracene. He explored the conditions necessary to make accurate measurements and then studied the electronic processes in anthracene. The advent of lasers allowed him, with Boris Stoicheff, to probe more deeply into these processes. This work was of considerable interest to major high-technology companies. Bill rose rapidly through the managerial structure of the NRC and became its president in 1967, serving for 13 years, the longest of any president. After retiring, Bill served for several years with the International Union of Pure and Applied Chemistry, two of them as its president, and remained active as a chemical consultant, advising small start-up companies. He died at the age of 97 years in Ottawa.
