Sulfur in a Fossil Wood from the Pleistocene Marine Clay

In anoxic marine sediments sulfur is considered to be essential to the formation of humic substances. It is also estimated that sulfur may play a crucial role in the degradation of wood buried in marine sediments. In order to confirm this prediction, we observed the tissue of fossil wood from the marine clay aged 1.1 million years by polarizing microscopy and SEM before the determination of its sulfur content by PIXE and EXDA, and its distribution by mu-PIXE. Results show that the sample contained about 6000 mug/g of total sulfur and tracheid cells with birefringence, which have probably preserved the original wood components contain less sulfur compared to those without birefringence, which are heavily degraded. This might suggest the participation of sulfur in the degradation or the formation of humic substances occurred in wood tissue during diagenesis

Elemental analysis of Worker Mandibles of Coptotermes formosanus (Isoptera: Rhinotermitidae)

Mandibles of workers of Coptotermes formosanus Shiraki were subjected to normal- and micro- PIXE analyses to obtain their elemental profiles. Among 14 elements, Mn and Fe were evidenced to accumulate in mandibles by normal-PIXE analysis. By micro-PIXE analysis, Mn was found to preferentially distribute in the cutting edges (teeth) where the pigmentation is also strongest. This may suggest that Mn deposition contributes to the hardening of the exoskeleton, and that the deposition is closely related to pigmentation pattern

Mandibles of Japanese subterranean termites, Coptotermes formosanus Shiraki and Reticulitermes speratus (Kolbe)

Worker mandibles of two economically important subterranean pest termites, Coptotermes formosanus Shiraki and Reticulitermes speratus (Kolbe), were investigated for their chemical properties and arrangement with special reference to the pigmentation and the particle-removing capacity. Both species deposited Mn in cutting edges of mandibles, and the deposition seemed to be closely related to the pigmentation and the hardening of the mandibles.The maximum openings of mandibles and maxillaes of C.formosanus workers were 0.45mm and 0.88mm, respectively, and the minimum gap between mandibles and maxillaes was 0.07mm.This theoretically results in that C.formosanus workers can remove particles with less than 1.9mm diameters if the particle is spherical in shape, coinciding well with the laboratory test results that 1.7-2.4mm sized particles were effective to prevent the invasion of workers of C.formosanus. In addition, workers of C.formosanus showed the maximum head width of approximately 1.2mm, indicating the particles with less than 2.9mm diameters are small enough to prevent the invasion of workers of C.formosanus. This also has no contradiction with the laboratory test results. These results strongly suggest that basic researches on termite mandibles can be the breakthrough to develop not only new termite control measures but also new biomimetic composite materials