3-Amino-2-methylpyrrolidines were prepared via a novel protocol, involving the reductive ring closure and O-deprotection of gamma-acetoxy-alpha-chloroketimines towards 2-(2-hydroxyethyl)-3-methylaziridines, followed by ring expansion of the latter into 3-bromopyrrolidines via intermediate bicyclic aziridinium salts and consecutive nucleophilic displacement of the bromo atom by azide towards 3-a...

we introduce center-like subsets z*(r,f), z**(r,f) and z1(r,f), where r is a ring and f is a map from r to r. for f a derivation or a non-identity epimorphism and r a suitably-chosen prime or semiprime ring, we prove that these sets coincide with the center of r.

let r be a prime ring with extended centroid c, h a generalized derivation of r and n ⩾ 1 a xed integer. in this paper we study the situations: (1) if (h(xy))n = (h(x))n(h(y))n for all x; y 2 r; (2) obtain some related result in case r is a noncommutative banach algebra and h is continuous or spectrally bounded.

Ríos et al. (2004) report in this issue that the Golgi protein GMAP-210 is sufficient to confer pericentrosomal positioning and recruits gamma-tubulin and associated microtubule-nucleating ring complex proteins to Golgi membranes. The results raise the possibility that short microtubules emanate from the Golgi to mediate its organization and positioning.

The asymmetric synthesis of gamma-azido trans-cyclopropyl ketones is accomplished via a short, simple and efficient sequence. The cyclopropanation step is achieved by an intramolecular nucleophilic ring closure, with a diphenylphosphinate leaving group, to give trans-cyclopropane exclusively. beta-Keto-diphenylphosphine oxides cyclise to form optically active dihydrofurans. All possible diaster...

Optical images of SN 1987A show a triple ring structure. The inner (dust) ring has recently increased in brightness and in the number of hot spots suggesting that the supernova shock wave has collided with the dense pre-existing circumstellar medium, a scenario supported by radio and X-ray observations. Such a shocked environment is widely expected to result in the acceleration of charged parti...

The structure of a new antitumor antibiotic, myrocin C, from a strain of Myrothecium verrucaria was characterized as a pentacyclic pimarane diterpene composed of a gamma-lactol group and a unique cyclopropane ring on the basis of its physico-chemical properties and spectroscopic data as well as a single-crystal X-ray diffraction analysis of its monoacetyl derivative.

Based on a sample of (10.09$\pm$0.04)$\times$10$^{9}$ $J/\psi$ events collected with the BESIII detector operating at BEPCII storage ring, partial wave analysis decay $J/\psi \rightarrow \gamma\eta\eta'$ is performed. An isoscalar state exotic quantum numbers $J^{PC}=1^{-+}$, denoted as $\eta_1(1855)$, has been observed for first time statistical significance larger than 19$\sigma$. Its mass an...

a ring $r$ is a strongly clean ring if every element in $r$ is the sum of an idempotent and a unit that commutate. we construct some classes of strongly clean rings which have stable range one. it is shown that such cleanness of $2 imes 2$ matrices over commutative local rings is completely determined in terms of solvability of quadratic equations.

Microtubules polymerise from nucleation templates containing gamma tubulin. These templates are generally concentrated in discrete structures called microtubule organising centres (MTOCs). In Schizosaccharomyces pombe, an equatorial MTOC (EMTOC) forms mid-way through anaphase B and then disassembles during the final stages of cell separation. We show that the EMTOC was generated by recruiting g...