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A discussion is given of the structure of a physical theory and an "ideal form" for such a theory is proposed. The essential feature is that all concepts should be defined in operational terms. Quantum (and classical) mechanics is then formulated in this way (the formulation being, however, restricted to the kinematical theory). This requires the introduction of the concept of a mixed test, related to a pure test (or "question") just as a mixed state is related to a pure state. In the new formulation, the primitive concepts are not states and observables but certain operationally accessible mixed states and tests called physical. The notion of a C·-system is introduced; each such system is characterized by a certain C*-algebra. The structure of a general C*-system is then studied, all concepts being dei1.ned in terms of physical states and tests. It is shown first how pure states and tests can be so defined. The quantum analog 'of the phase space of classical mechanics is then constructed and on it is built a mathematical structure, called a q-topology, which is a quantum analog of the topology of classical phase space. Mathematically, a q-topology is related to a noncommutative C·-algebra as an ordinary topology is related to a commutative C*-algebra. Some properties of the q-topology of a C*-system are given. An appendix contains some physically motivated examples illustrating the theory.

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Trihydroxamate siderophores were isolated from iron-def icient cultures of three strains of Rhilobiurn legurninorarum biovar wiciae, two from Japan (WSM709, WSM710) and one from the Mediterranean (WU235), and from a Tn5-induced mutant of WSM710 (MNF7101). The first three all produced the same compound (vicibactin), which was uncharged and could be purified by solvent extraction into benzyl alcohol. The gallium and ferric complexes of vicibactin were extractable into benzyl alcohol at pH 59, while metal-free vicibactin could be extracted with good yield at pH 89. The trihydroxamate from MNF7101 (vicibactin 7101) could not be extracted into benzyl alcohol, but its cationic nature permitted purification by chromatography on Sephadex CM-25 (NHt form). Relative molecular masses and empirical formulae were obtained from fast-atom-bombardment MS. The structures were derived from one-and two-dimensional IH and I3C NMR spectroscopy, using DQF-COSY, NOESY, HMQC and HMBC techniques on the compounds dissolved in methanol-d, and DMSOd6. Vicibactin proves to be a cyclic molecule containing three residues each of (R)-2,5-diamino-N2-acetyl-N5-hydroxypentanoic acid (W-acetyl-M-hydroxy-Dornithine) and (R)-3-hydroxybutanoic acid, arranged alternately, with alternating ester and peptide bonds. Vicibactin 7101 differed only in lacking the acetyl substitution on the N2 of the W-hydroxyornithine, resulting in net positive charge; it was still functional as a siderophore and promoted 55Fe uptake by iron-starved cells of WSM710 in the presence of an excess of phosphate. The rate of vicibactin biosynthesis by iron-def icient cells of WSM710 was essentially constant between pH 5.5 and 79, but much decreased at pH 59. When iron-starved cultures were supplemented with potential precursors for vicibactin, the rates of i t s synthesis were consistent with both fi hydroxybutyrate and ornithine being precursors. At least three genes seem likely to be involved in synthesis of vicibactin from ornithine and fi hydroxybutyrate : a hydroxylase adding the -OH group to the N5 of ornithine, an acetylase adding the acetyl group to the N2 of ornithine, and a peptide synthetase system.

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Abstract. The strict topology ß on the space C(X) of bounded real-valued continuous functions on a topological space X was defined, for locally compact X, by Buck (Michigan Math. J. 5 (1958), 95-104). Among other things he showed that (a) C(X) is /3-complete, (b) the dual of C(X) under the strict topology is the space of all finite signed regular Borel measures on X, and (c) a Stone-Weierstrass theorem holds for /¡-closed subalgebras of C(X). In this paper the definition of the strict topology is generalized to cover the case of an arbitrary topological space and these results are established under the following conditions on X: for (a) X is a Ar-space; for (b) X is completely regular; for (c) Ais unrestricted.

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