Two pools of plant-derived C31 n-alkane occurring respectively as free and humin-bound forms in the same soil have been distinguished by C/C analyses. The results show that the humin-bound molecule is on the average 7 years older than the free molecule. These findings indicate that apolar organic substances can be trapped temporarily into the soil matrix by weak forces. Dans un même sol, la ten...

Chemistry of Dufour glands associated with the venom complex in Bracon cephi (Gahan) and Bracon lissogaster Muesebeck (Hymenoptera; Braconidae), two parasitoids of the wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), was examined by solid phase micro-extraction (SPME) and gas chromatography/mass spectrometry. Homologous series of five chemical classes were detected in individua...

A convergent synthesis of the C31-C52 bis-tetrahydropyran core of the natural product amphidinol 3 is reported. A common intermediate was synthesized from d-tartaric acid utilizing an asymmetric glycolate alkylation/ring-closing metathesis sequence to construct the THP rings. Differential elaboration of the common intermediate allowed the synthesis of two distinct coupling partners which were j...

Abstract. Plant wax n-alkane chain length distribution and isotopes have been studied in modern ecosystems as proxies to reconstruct vegetation climate of the past. However, most paleo-proxies focus on either concentrations or isotopes, whereas both carry complementary information mixing sources. We propose a multi-source model Bayesian framework that evaluates distributions simultaneously. The...