Tungsten isotope evidence from similar to 3.8-Gyr metamorphosed sediments for early meteorite bombardment of the Earth

The 'Late Heavy Bombardment' was a phase in the impact history of the Moon that occurred 3.8-4.0 Gyr ago, when the lunar basins with known dates were formed(1,2). But no record of this event has yet been reported from the few surviving rocks of this age on the Earth. Here we report tungsten isotope anomalies, based on the Hf-182-W-182 system (half-life of 9 Myr), in metamorphosed sedimentary rocks from the 3.7-3.8-Gyr-old Isua greenstone belt of West Greenland and closely related rocks from northern Labrador, Canada. As it is difficult to conceive of a mechanism by which tungsten isotope heterogeneities could have been preserved in the Earth's dynamic crust-mantle environment from a time when short-lived Hf-182 was still present, we conclude that the metamorphosed sediments contain a component derived from meteorites.

4,6,8,10,16-penta- and 4,6,8,10,16,18-hexamethyldocosanes from the cane beetle Antitrogus parvulus - Cuticular hydrocarbons with unprecedented structure and stereochemistry

[GRAPHICS] The major cuticular hydrocarbons from the cane beetle species Antitrogus parvulus were deduced to be 4,6,8,10,16,18-hexa- and 4,6,8,10,16-pentamethyldocosanes 2 and 3, respectively. Isomers of 2,4,6,8-tetramethylundecanal 27, 36, and 37, derived from 2,4,6-trimethylphenol, were coupled with the phosphoranes 28 and 29 to furnish alkenes and, by reduction, diastereomers of 2 and 3. Chromatographic and spectroscopic comparisons confirmed 2 as either 6a or 6b and 3 as either 34a or 34b.

Cross-border insolvency: Adoption of CLERP 8 as an evolution of Australian insolvency law

In 1997 the United Nations adopted the UNCITRAL Model Law on Cross-Border Insolvency and recommended that member states adopt it as part of domestic legislation. In 2002 Australia, an active participant in UNCITRAL's Working Group on Insolvency Law, announced that the next phase of the Commonwealth Government's Corporate Law Economic Reform Program would be a review of cross-border insolvency law. CLERP 8 seeks feedback on the proposed enactment of the Model Law by a separate Commonwealth statute. This article places such a development within the context of Australian cross-border insolvency law as it has evolved from early English bankruptcy legislation through case law arising from the banking collapses of the late 19th century to the more recent jurisprudence produced by corporate collapses of the late 1980s to early 1990s and current high-profile insolvencies.

A longitudinal analysis of sex differences in bone mineral accrual in healthy 8-19-year-old boys and girls

Background: Although early in life there is little discernible difference in bone mass between boys and girls, at puberty sex differences are observed. It is uncertain if these differences represent differences in bone mass or just differences in anthropometric dimensions. Aim: The study aimed to identify whether sex independently affects bone mineral content (BMC) accrual in growing boys and girls. Three sites are investigated: total body (TB), femoral neck (FN) and lumbar spine (LS). Subjects and methods: 85 boys and 67 girls were assessed annually for seven consecutive years. BMC was assessed by dual energy X-ray absorptiometry (DXA). Biological age was defined as years from age at peak height velocity (PHV). Data were analysed using a hierarchical (random effects) modelling approach. Results: When biological age, body size and body composition were controlled, boys had statistically significantly higher TB and FN BMC at all maturity levels (p < 0.05). No independent sex differences were found at the LS (p > 0.05). Conclusion: Although a statistical significant sex effect is observed, it is less than the error of the measurement, and thus sex difference are debatable. In general, sex difference are explained by anthropometric difference

Geometric isomers of chloro(6-methyl-1,4,8,11-tetraazacyclotetradecane-6-amine)cobalt(III) tetrachlorozincate(II)

The crystal structures of a pair of cis and trans isomers of the macrocyclic chloropentaamine title complex, as their tetrachlorozincate(II) salts, [CoCl(C11H27N5)][ZnCl4], are reported. The two distinct isomeric forms lead to significant variations in the Co-N bond lengths and, furthermore, hydrogen bonding between the complex ions is influenced by the folded (cis) or planar (trans) conformations of the coordinated ligand.

Isomers of 1,4,8,11-tetraazacyclotetradecane-6,13-dicarboxylate characterized as cobalt(III) complexes

The major trans (1) and minor cis (2) isomers of 1,4,8,11-tetraazacyclotetradecane-6,13-dicarboxylate have been characterized as the complexes [Co(1)](ClO4) and [Co(H-2)(OH2)]Cl(ClO4).H2O. The former crystallized in the C-2/c space group and the latter in the P2(1)/c space group, with cell parameters a 16.258(7), b 9.050(3), c 15.413(6) Angstrom, beta133.29(3)degrees, and a 9.694(4), b 16.135(1), c 12.973(5) Angstrom, beta 93.00(2)degrees, respectively. Their characterization completes identification of the respective trans and cis isomers for the series of C-pendant macrocycles also including 1,4,8,11-tetraazacyclotetradecane-6-amine-13-carboxylate ((3), (4)) and 1,4,8,11-tetraazacyclotetradecane-6,13-diamine ((5), (6)). The complexes show limited distortion from octahedral geometry with the strain in the presence of the coordinated C-pendant carboxylate significantly reduced compared with that for the C-pendant amine in analogues, a consequence mainly of six-membered as opposed to five-membered chelate rings involving the pendant donor. A comparison of the physical properties for the trans isomers of the octahedral complexes of (1), (3), and (5), which reflect progressively increasing strain, is presented.