Chemoselective photorearrangements of diazinobarrelenes. Deuterium labeling study.

Chemoselective photorearrangements of pyrazino-, quinoxalino-, and benzoquinoxalinobarrelenes were investigated by deuterium-labeling experiment. Photolysis of pyrazinobarrelene 4 and quinoxalinobarrelene 5 with 300 nm region light under either direct or sensitized conditions afforded semibullvalenes 7 and 8, respectively; benzoquinoxalinobarrelene 6 was inert to both reaction conditions. Irradiation of deuterated pyrazinobarrelene 4-d4 and quinoxalinobarrelene 5-d4 afforded deuterated semibullvalenes 7-d4-A-7-d4-F and 8-d4-A-8-d4-F, respectively.

Molecular detection and direct enumeration of methanogenic Archaea and methanotrophic Bacteria in domestic solid waste landfill soils.

Methane oxidizing and producing activities of cover soil (10, 30 cm depth) and burial waste (1, 3 m depth) were evaluated: top cover soil (10 cm) had the highest methane oxidizing activity, while 1 m depth buried waste showed the highest methane producing potential. All the sequences of the 1 m sample were found to be closely related to 16S rDNAs of mainly hydrogenotrophic methanogens known, such as genera Methanosarcina, Methanoculleus, and Methanobacterium. We developed a modified fluorescence in situ hybridization (FISH) direct counting method for landfill samples, resulting in the detection of approx.

Archaeal community compositions at different depths (up to 30 m) of a municipal solid waste landfill in Taiwan as revealed by 16S rDNA cloning analyses.

Archaeal 16S rDNA clone libraries were constructed for samples taken at 10, 20 and 30 m depth in a landfill, which corresponded approximately 3, 6 and 9 years operation, respectively. Sequencing and phylogenetic analyses of representative clones showed that all of the rDNAs were closely related to typical methanogens. The distributions of phylotypes in clone libraries were similar to each other.