Earthworm-Collembola interactions affecting water-soluble nutrients, fauna and physiochemistry in a mesocosm manure-straw composting experiment.

A mesocosm fermentation experiment was undertaken to investigate interactions between Eisenia fetida and Collembola affecting composting processes. Earthworms, Collembola, respiration, water soluble nutrients and compost characteristics (near infrared spectra - NIRS) were monitored on four occasions over 136 days. Earthworms were the main drivers of early changes in composts, increasing the general abundance of Collembola, although responses varied with species. Earthworms accelerated substrate mineralisation and release of soluble nutrients whilst also changing compost characteristics. Collembola alone had little direct effect on soluble nutrient concentrations or respiration; they did however alter compost characteristics (NIR spectra). Earthworm-Collembola interactions affecting respiration and soluble nutrients were mainly antagonistic in the early stages of composting but synergistic in later stages. In the later stages of composting, the higher abundance of Collembola when combined with earthworms resulted in greater concentrations of soluble nitrate and phosphate. These findings emphasise the importance in vermicomposting practice of different invertebrate groups having access to feedstock at appropriate stages of the process. The high concentrations of soluble nutrients released during vermicomposting indicate the need for control measures to avoid off-site pollution and loss of this resource.

Characterization of Si nanocrystals by different TEM-based techniques.

Silicon nanocrystals (Si-nc) embedded in SiO(2) matrix and obtained by ion implantation (50keV, 1.0x10(17)Si/cm(2)) were characterized by means of three different transmission electron microscopy (TEM) techniques: Dark Field (DF), Scanning TEM Annular Dark Field (STEM-ADF) and Z contrast. The strengths and weaknesses of each technique for the characterization of the Si-nc were evaluated and discussed. DF imaging, which has the best contrast, was chosen to give the average Si-nc size evaluated to 5.6nm. On the other hand, STEM-ADF, which is only sensitive to the crystalline phase, provided an evaluation of the Si-nc density of 3.27x10(17)nc/cm(3). Finally, comparison between the STEM-ADF and Z contrast imaging permitted to evaluate the amorphous phase remaining after the annealing to around 12%.

Systematic procedure for indexing HOLZ lines in convergent beam electron diffraction patterns of cubic crystal.

This article has been written for experimenters who are beginning to work with convergent beam electron diffraction patterns (CBED). The indexing of the higher-order Laue zone (HOLZ) lines inside the central spot of a CBED pattern is the first step towards studying variations in lattice parameter and three-dimensional (3D) symmetry. To index the HOLZ lines one must construct and index the HOLZ, find its interplanar spacing and the location of its projection on the zero order Laüe zone (ZOLZ) for a given zone axis, and finally find the radius of the HOLZ ring. A computer program has been developed to perform all these tasks for cubic crystals and is very useful, especially when one varies parameters such as operating voltage, zone axis, lattice parameter, and crystalline structure.