Submicroscopic structure of the egg shell of helminth II. A study on Trichuris vulpis

Electron microscopic structures of the egg shell and the plug of the ova of Trichuris vulpis have been demonstrated. The shell is of one thick membrane of about 4 microns in thickness and consisted of several opaque and less opaque layers arranged in parallel and alternatively. The plug is of transparent substance having opaque limiting membrance on the surface and being consisted of meshwork of microfibrils.</p

A Study on the Structure of Egg Shell of Enterobius Vermicularis (Linnaeus, 1758) Leach, 1853, with the Electron Microscope

1. The shell of the ova of Enterobius vermicularis is composed of two chitinous layers, a compact outer layer and a looser inner layer. Both surfaces of the two layers have a dense border. 2. The outer layer has innumerable tubules about 0.2 micron in diameter, and only those tubules found in the thinner part of the layer open to the outside and inside. 3. The outer layer of mature eggs is about 0.45 micron and the inner layer about 2 to 6 microns, in thickness. 4. The chitinous microfibrils in both layers form a rcticular structure which contains very fine granules in the mesh.</p

Use of a process-based model for assessing the methane budgets of global terrestrial ecosystems and evaluation of uncertainty

We assessed the global terrestrial budget of methane (CH&lt;sub&gt;4&lt;/sub&gt;) by using a process-based biogeochemical model (VISIT) and inventory data for components of the budget that were not included in the model. Emissions from wetlands, paddy fields, biomass burning, and plants, as well as oxidative consumption by upland soils, were simulated by the model. Emissions from ruminant livestock and termites were evaluated by using an inventory approach. These CH&lt;sub&gt;4&lt;/sub&gt; flows were estimated for each of the model's 0.5&amp;deg; &amp;times; 0.5&amp;deg; grid cells from 1901 to 2009, while accounting for atmospheric composition, meteorological factors, and land-use changes. Estimation uncertainties were examined through ensemble simulations using different parameterization schemes and input data (e.g., different wetland maps and emission factors). From 1996 to 2005, the average global terrestrial CH&lt;sub&gt;4&lt;/sub&gt; budget was estimated on the basis of 1152 simulations, and terrestrial ecosystems were found to be a net source of 308.3 &amp;plusmn; 20.7 Tg CH&lt;sub&gt;4&lt;/sub&gt; yr&lt;sup&gt;−1&lt;/sup&gt;. Wetland and livestock ruminant emissions were the primary sources. The results of our simulations indicate that sources and sinks are distributed highly heterogeneously over the Earth's land surface. Seasonal and interannual variability in the terrestrial budget was also assessed. The trend of increasing net emission from terrestrial sources and its relationship with temperature variability imply that terrestrial CH&lt;sub&gt;4&lt;/sub&gt; feedbacks will play an increasingly important role as a result of future climatic change

Pure iron grains are rare in the universe

The abundant forms in which the major elements in the universe exist have been determined from numerous astronomical observations and meteoritic analyses. Iron (Fe) is an exception, in that only depletion of gaseous Fe has been detected in the interstellar medium, suggesting that Fe is condensed into a solid, possibly the astronomically invisible metal. To determine the primary form of Fe, we replicated the formation of Fe grains in gaseous ejecta of evolved stars by means of microgravity experiments. We found that the sticking probability for formation of Fe grains is extremely small; only several atoms will stick per hundred thousand collisions, so that homogeneous nucleation of metallic Fe grains is highly ineffective, even in the Fe-rich ejecta of Type Ia supernovae. This implies that most Fe is locked up as grains of Fe compounds or as impurities accreted onto other grains in the interstellar medium