The biomechanics of amnion rupture: an X-ray diffraction study

Pre-term birth is the leading cause of perinatal and neonatal mortality, 40% of which are attributed to the pre-term premature rupture of amnion. Rupture of amnion is thought to be associated with a corresponding decrease in the extracellular collagen content and/or increase in collagenase activity. However, there is very little information concerning the detailed organisation of fibrillar collagen in amnion and how this might influence rupture. Here we identify a loss of lattice like arrangement in collagen organisation from areas near to the rupture site, and present a 9% increase in fibril spacing and a 50% decrease in fibrillar organisation using quantitative measurements gained by transmission electron microscopy and the novel application of synchrotron X-ray diffraction. These data provide an accurate insight into the biomechanical process of amnion rupture and highlight X-ray diffraction as a new and powerful tool in our understanding of this process

Oxidation of Reduced Sulfur Species: Carbon Disulfide

Article on the oxidation of reduced sulfur species and carbon disulfide

Characterization of extractives from biomasses of the alpine forests and their antioxidative efficacy

Tree species typical of the alpine forests can be valued not only as sources of timber, but also as raw tissues for the recovering of extractives with significant antioxidant activity (AA). To improve knowledge about the ex- tractive content in these trees and to investigate whether there is a correlation between extract composition and AA, heartwoods, sapwoods, barks, knotwoods, twigs and needles of seven of the most common tree species from the alpine region were extracted with different solvents by Accelerated Solvent Extraction (ASE). The extracts were characterized by GC–MS for fatty and resin acids, TD-GC/MS for terpenes, HPLC-UV for phenolic mono- mers and condensed tannins (CT), and GC-FID for mono- and polysaccharides. The AA of the extracts were thereafter estimated using the DPPH assay. The exact composition of extractives derived was highly characteristic of each specific plant tissue, and some general trends were observed. The richest tissues in extractives (18.6–39.0% on dry tissue) were barks and needles. However, sapwoods showed a very low presence of extractives (5.2–7.5%). The main extractable compounds from bark were CT and polysaccharides, while phenolic monomers and monosaccharides re- presented the majority of needle extractives. Terpenes were mostly detected in twigs. The composition of ex- tractives for heartwoods and knotwoods were more scattered and closely associated to the tissues. A significant correlation between the extract composition and their AA was demonstrated by a multiple linear regression analysis (p-value<0.001). The most effective compounds contributing to the high AA of the extracts were CT. Plant tissue rich in condensed tannins like European oak heartwood, Scots pine bark and Norway spruce bark, should therefore be considered as the most suitable sources for natural antioxidants from the alpine region. However, the findings need to be validated with further antioxidant assays. 1

Oxidation of Reduced Sulfur Species: Carbon Disulfide

Article on the oxidation of reduced sulfur species and carbon disulfide

Oxidation of Reduced Sulfur Species: Carbon Disulfide

A detailed chemical kinetic model for oxidation of CS₂ has been developed, on the basis of ab initio calculations for key reactions, including CS₂ + O₂ and CS + O₂, and data from literature. The mechanism has been evaluated against experimental results from static reactors, flow reactors, and shock tubes. The CS₂ + O₂ reaction forms OCS + SO, with the lowest energy path involving crossing from the triplet to the singlet surface. For CS + O₂, which yields OCS + O, we found a high barrier to reaction, causing this step to be important only at elevated temperatures. The model predicts low temperature ignition delays and explosion limits accurately, whereas at higher temperatures it appears to overpredict both the induction time for CS₂ oxidation and the formation rate of [O] upon ignition. The predictive capability of the model depends on the accuracy of the rate constant for the initiation step CS₂ + O₂, which is difficult to calculate due to the intersystem crossing, and the branching fraction for CS₂ + O, which is measured only at low temperatures. The governing reaction mechanisms are outlined on the basis of calculations with the kinetic model