Cyclopolymerization. VII. The 13C NMR Spectra of Cyclopolymers Obtained from N,N-Diallyamines

Pulsed Fourier transform ¹³C natural abundance nuclear magnetic resonance spectroscopy has been used to determine the structures of the polymers formed by the radical-induced cyclopolymerization of N-substituted-N, N-diallylamines and N-methyl-N, N-bls(2-alkylallyl)-amines. The polymers of N, N-diallylamines all contain cis-and trans-substituted pyrrolidine rings in the ratio 5:1. The polymers of N-methyl-N, N-bis(2-alkylallyl)amines give complex spectra due to the presence of both cis-and trans-pyrrolidine and -piperidine rings, but the difference in chemical shifts of the N-methyl signals from the different structural types allows the spectra to be analyzed.     

2p-1h states in 17N

States populated in the ¹⁵N(t,p)¹⁷N reaction at 15 MeV are compared with those in the ¹⁶O(t,p)¹⁸O reaction at the same energy. On the basis of this comparison several spins and parities are assigned. Cross-section ratios are in rough agreement with a weak-coupling model.     

Elucidation of the structure of a highly efficient blue electroluminescent material

We determined that the structure of the previously published highly efficient blue electroluminescent borate complex, lithium tetra(2-methyl-8-hydroxyquinolato) boron, does not contain boron. Rather, it is the lithium salt of 2-methyl-8-hydroxyquinoline.     

Nuclear magnetic resonance on the 10−, 0.88 ms state in 206Bi

Alpha-particle reduced widths for the 8⁺ state at 11.95 MeV, obtained from analysis of both ¹⁶O + α resonant scattering data and ¹⁶O(⁶Li, d)²⁰Ne reaction data are consistent with expectation for the 8⁺ member of the ground-state rotational band.     

Cathodic voltammetric determination of gold

Cathodic voltammetry at a carbon paste electrode has been evaluated as a technique for the analysis of gold. In the absence of interfering elements the technique is suitable for determinations at concentrations down to 10^?6M. Differentiation of the reduction peak current increases the sensitivity, permitting the determination of gold at concentrations of 10^?7M.     

Cyclopolymerisation. 7. Mitt. Die13C-NMR-Spektren von Cyclopolymeren aus N,N-Diallylaminen

Ohne Zusammenfassung     

Elementary and middle grade students’ constructions of typicality

This study addresses the measures chosen by students when selecting or constructing indices to properties of distributions of data. A series of individual teaching experiments were conducted to provide insight into the development of five 4th to 8th grade students’ conceptualizations of distribution over the course of 8 weeks of instruction. During the course of the teaching experiment (emergent) statistical tasks and analogous teacher activities were created and refined in an effort to support the development of understanding. In the process of development, attempts were made by students to coordinate center and variability when constructing measures to index properties of distributions. The results indicate that consideration of representativeness was a major factor that motivated modification of approaches to constructing indices of distributions, and subsequent coordination of indices of variation and center. In particular, the defining features of student's self-constructed “typical” values and notions of spread were examined, resulting in a model of development constituting eight “categories” ranging from the construction of values that did not reflect properties of the data (Category 1) to measures employing conceptual use of the mean in combination with other indices of center and spread (Category 8).     

Practical synthetic routes to carbon-substituted nucleosides

Robust practical routes to three different carbon-substituted nucleosides are described. Short synthetic procedures for preparing 1′-homonucleosides, 2′-C-methyl-carbanucleosides and 2′-C-methyl-cyclopropyl/cyclopentyl fused bicyclic ribose analogues are described starting from readily available building blocks.