ABSTRACT
We present novel means to hyperpolarize deuterium nuclei in 13CD2 groups at cryogenic temperatures. The method is based on cross-polarization from 1H to 13C and does not require any radio-frequency fields applied to the deuterium nuclei. After rapid dissolution, a new class of long-lived spin states can be detected indirectly by 13C NMR in solution. These long-lived states result from a sextet-triplet imbalance (STI) that involves the two equivalent deuterons with spin I = 1. An STI has similar properties as a triplet-singlet imbalance that can occur in systems with two equivalent I = 12 spins. Although the lifetimes TSTI are shorter than T1(Cz), they can exceed the life-time T1(Dz) of deuterium Zeeman magnetization by a factor of more than 20.
ABSTRACT
The intensity of construction of foraging access holes by two leaf-litter feeding, soil- inhabiting termite species, Syntermes molestus and Syntermes spinosus, in a Central Amazonian rain forest, was observed on consecutive nights for two weeks. Between 11 and 48 nest entrances per m2 were counted. Interaction between the two species was intense; some entrance holes were overtaken by the larger species during the observations; however, both species coexist in the area. A calculated minimum of 35 entrances/m2 is built every year by both species, emphasizing the importance of soil-burrowing termites for soil structure, aeration and water regime.
A intensidade de construções de saídas de forrageamento em duas espécies de cupins subterrâneos que se alimentam de serrapilheira, Syntermes molestus e S. spinosus, numa floresta tropical úmida da Amazônia Central, foi observada em noites consecutivas durante duas semanas. Foram contadas entre 11 e 48 entradas de ninho por m2. A interação entre as duas espécies foi intensa; alguns dos olheiros foram conquistados pela espécie maior durante as observações; mesmo assim, ambas espécies coexistem na área. Um mínimo calculado de 35 entradas/m2 é construído cada ano por ambas as espécies, o que enfatiza a importância de cupins de solo para a estrutura, aeração e regime hídrico do solo.