Strongly baryon-dominated disk galaxies at the peak of galaxy formation ten billion years ago.

In the cold dark matter cosmology, the baryonic components of galaxies-stars and gas-are thought to be mixed with and embedded in non-baryonic and non-relativistic dark matter, which dominates the total mass of the galaxy and its dark-matter halo. In the local (low-redshift) Universe, the mass of dark matter within a galactic disk increases with disk radius, becoming appreciable and then dominant in the outer, baryonic regions of the disks of star-forming galaxies. This results in rotation velocities of the visible matter within the disk that are constant or increasing with disk radius-a hallmark of the dark-matter model.

1-(p-carbamoylphenyl)-3,3-dimethyl-triazene, an antitumour agent.

In the crystal structure of the title compound, 4-(3,3-dimethyl-1-triazeno)benzamide, C9H12N4O, (2), the N = N double bond [1.282 (8) A] is 0.030 A shorter than the N--N single bond [1.

Application of 15N nuclear magnetic resonance spectroscopy to the determination of the stability of aryl nitrogen mustards.

An excellent correlation has been shown to exist between the 15N NMR chemical shifts of a series of aryl nitrogen mustards and the Hammett constant, sigma, which is much improved by the use of sigma-. These chemical shifts also correlate well with the hydrolysis rates of the compounds in 50% aqueous acetone at 66 degrees C and their alkylation of 4-(4'-nitrobenzyl)pyridine under similar conditions. Thus 15N NMR is a straightforward and material-conserving method for estimating the relative stabilities of aryl nitrogen mustards.

Alkylation of DNA by the nitrogen mustard bis(2-chloroethyl)methylamine.

Alkylation of DNA by the nitrogen mustard bis(2-chloroethyl)methylamine (mechlorethamine; HN2) gave four principal products, derived by mono-alkylation of guanine at N-7 and adenine at N-3 and by cross-linking of guanine to guanine or guanine to adenine at these positions. These products were isolated by hydrolysis from DNA at neutral pH, followed by ion-exchange chromatography on SP-Sephadex and reversed phase chromatography on ODS. They were characterized by identification with products from the reaction of nitrogen mustard with adenine or deoxyguanylic acid, and by their UV, mass, and proton magnetic resonance spectra.

Synthesis and cytotoxicity of potential tumor-inhibitory analogues of trimelamol (2,4,6-tris[(hydroxymethyl)methylamino]-1,3,5-triazine) having electron-withdrawing groups in place of methyl.

In exploring the structural features which determine the antitumor activity of 2,4,6-tris-[(hydroxymethyl)methylamino]-1,3,5-triazine (trimelamol, 1), we have synthesized analogues in which the methyl groups have been replaced by the electron-withdrawing substituents 2,2,2-trifluoroethyl (5), propargyl (13), and cyanomethyl (15) via the respective tris(alkylamino)triazines 3, 12, and 14. Three mono[(hydroxymethyl)amino]triazines (4, 7, and 10) were also prepared. All the new tris(hydroxymethyl) derivatives showed cytotoxicities toward a variety of experimental rodent and human ovarian tumor cell lines similar to those shown by 1, the cyanomethyl analogue (15) having the most favorable profile.