Intensified continental chemical weathering and carbon-cycle perturbations linked to volcanism during the Triassic-Jurassic transition.

Direct evidence of intense chemical weathering induced by volcanism is rare in sedimentary successions. Here, we undertake a multiproxy analysis (including organic carbon isotopes, mercury (Hg) concentrations and isotopes, chemical index of alteration (CIA), and clay minerals) of two well-dated Triassic-Jurassic (T-J) boundary sections representing high- and low/middle-paleolatitude sites. Both sections show increasing CIA in association with Hg peaks near the T-J boundary.

The largest negative carbon isotope excursions in Neoproterozoic carbonates caused by recycled carbonatite volcanic ash.

The late Ediacaran Shuram Excursion (SE) records the most prominent negative δC excursions (δC = -12‰) during Earth's history. It has been hypothesized to have resulted from oxidation of dissolved organic matter, diagenetic or authigenic precipitates. However, the origin of the SE remains enigmatic; current models face challenges regarding the significant amount of atmospheric oxygen needed to balance such extensive oxidation and sustained inputs of light carbon with extremely negative C isotope compositions.

Evidence for a prolonged Permian-Triassic extinction interval from global marine mercury records.

The latest Permian mass extinction, the most devastating biocrisis of the Phanerozoic, has been widely attributed to eruptions of the Siberian Traps Large Igneous Province, although evidence of a direct link has been scant to date. Here, we measure mercury (Hg), assumed to reflect shifts in volcanic activity, across the Permian-Triassic boundary in ten marine sections across the Northern Hemisphere. Hg concentration peaks close to the Permian-Triassic boundary suggest coupling of biotic extinction and increased volcanic activity.

Time-calibrated Milankovitch cycles for the late Permian.

An important innovation in the geosciences is the astronomical time scale. The astronomical time scale is based on the Milankovitch-forced stratigraphy that has been calibrated to astronomical models of paleoclimate forcing; it is defined for much of Cenozoic-Mesozoic. For the Palaeozoic era, however, astronomical forcing has not been widely explored because of lack of high-precision geochronology or astronomical modelling.

Expression of e-cadherin and beta-catenin in human esophageal squamous cell carcinoma: relationships with prognosis.

Aim: To elucidate the expression of E-cadherin and beta-catenin correlating with its clinical outcome in patients with esophageal squamous cell carcinoma (ESCC), by analyzing their interrelationship with clinicopathological variables and their effects on progress and prognosis.

Methods: Expression of E-cadherin and beta-catenin was determined by SP immunohistochemical technique in patients with ESCC consecutively, their correlation with clinical characteristics was evaluated and analyzed by multivariate analysis.

Results: The rate of expression of E-cadherin decreased to 66.