Rotationally resolved absorption spectra of the e A 1 P u — e X 1 R þ g origin band of the tricarbon molecule (C 3) are reported for 12 C 3 and its 13 C-substitued isotopologues. The 4051 Å electronic transition, also identified in cometary tails and in translucent interstellar clouds, has been measured using cavity ring-down spec-troscopy and a supersonically expanding planar plasma. Previous ...

The ligand 4,4'-bipyrimidine combines a chelating bipyridine group and two terminal donor atoms into a single molecule; chelation to a single Ag(I) centre forms a square planar complex which can then form an extended planar ladder-type polymer by linking through linear Ag(I) centres whereas bis-coordination to an octahedral Co(II) centre yields a building block with four external donor nitrogen...

A graph G is almost 4-connected if it is simple, 3-connected, has at least five vertices, and V (G) cannot be partitioned into three sets A,B,C in such a way that |C| = 3, |A| ≥ 2, |B| ≥ 2, and no edge of G has one end in A and the other end in B. A graph K is a subdivision of a graph G if K is obtained from G by replacing its edges by internally disjoint nonzero length paths with the same ends...

This article contains a mathematical analysis of strategies for determining topological consistency of vector map simplifications. Such techniques exploit assumptions that can be made regarding the similarity of corresponding objects in successive simplifications. We propose that all topological relationships may be classified as planar or non-planar. A formal analysis of techniques for determi...

We introduce a new approach for drawing diagrams. Our approach is to use a technique we call confluent drawing for visualizing non-planar graphs in a planar way. This approach allows us to draw, in a crossing-free manner, graphs—such as software interaction diagrams—that would normally have many crossings. The main idea of this approach is quite simple: we allow groups of edges to be merged tog...

Tutte founded the theory of enumeration of planar maps in a series of papers in the 1960s. Rooted non-separable planar maps have connections, for example, to pattern-avoiding permutations, and they are in one-to-one correspondence with the β(1, 0)-trees introduced by Cori, Jacquard and Schaeffer in 1997. In this paper we enumerate 2-face-free rooted non-separable planar maps and obtain restrict...

In the planar title mol-ecule, C(16)H(16)N(2)O(4)·C(2)H(6)O, the planar Schiff base molecule is linked to the ethanol solvent mol-ecule by a hydr-oxy-amide hydrogen bond. The hydr-oxy group of the ethanol mol-ecule is a hydrogen-bond donor to the double-bonded N atom of an adjacent Sciff base, pairs of interactions taking place across a center of symmetry and giving rise to a hydrogen-bonded di...

Maximum capacities were determined for adsorption of six polycyclic aromatic hydrocarbons, seven polychlorinated biphenyls, and five chlorobenzenes in both the slowly desorbing domain and the very slowly desorbing domain of a sediment. For separate compound classes in the two desorption domains, log-transformed maximum adsorption capacities were linearly related to the relative magnitude of the...

Problems of elastic wave scattering by surface-breaking and near-surface cracks are of considerable current interest for ultrasonic nondestructive evaluation. Ultrasonic scattering by planar cracks near or at the free surface of a semi-infinite elastic homogeneous medium has been studied theoretically by many authors. References to recent papers on this subejct can be found in [1], [2] and [3]....