Fe-mediated biological nitrogen fixation is thought to proceed via either a sequence of proton and electron transfer steps, concerted H atom transfer steps, or some combination thereof. Regardless of the specifics and whether the intimate mechanism for N2-to-NH3 conversion involves a distal pathway, an alternating pathway, or some hybrid of these limiting scenarios, Fe-NxHy intermediates are im...

background: the accuracy of pedicle screw placement is essential for lumbar and thoracolumbar spine fracture fixation. purpose: the aim of the present study was to assess the accuracy of the pedicle screw placement with conventional c-arm fuoroscopy-guided in these patients. methods: a retrospective review identified patients who underwent operative management with thoracolumbar instruments at ...

N limitation to primary production and other ecosystem processes is widespread. To understand the causes and distribution of N limitation, we must understand the controls of biological N fixation. The physiology of this process is reasonably well characterized, but our understanding of ecological controls is sparse, except in a few cultivated ecosystems. We review information on the ecological ...

Global com parisons suggest that rates o f N fixation in tropical rain forests m ay be am ong the highest on earth. However, data supporting this contention are rare, and the factors th a t regulate N hxation w ithin the biom e rem ain largely unknow n. W e conducted a full-factorial (N X P) fertilization experim ent in two lowland tropical rain forests in C osta Rica to explore the effects o f...

in order to study the effect of salinity stress and nitrogen forms on nitrogen remobilization from root to shoot following defoliation and shoot dry matter production, a research in the form of factorial experiment based on randomized block, was designed in three replications. treatments include: 1) nitrogen forms containing a) biological n fixation (n1), b) 6mm nh4no3(n2), c) biological n fixa...

Rising atmospheric carbon dioxide (Ca), a product of fossil fuel burning, land-use change, and cement manufacture, is expected to cause a large carbon sink in land ecosystems, partly mitigating human-driven climate change (1). Increasing biological nitrogen fixation with rising Ca has been invoked as a means to provide the N necessary to support C accumulation (2). As in many short-term experim...

Soil carbon (C), nitrogen (N), and phosphorus (P) are three important elements. The study of stoichiometric relationships soil C, N, P in tropical forests on Hainan Island, China could improve our understanding nutrient cycling provide valuable information for forest management. samples were collected at five different depths from 0 to 100 cm sites among four types total concentrations measured...

We measured N2 fixation rates from oceanic zones that have traditionally been ignored as sources of biological N2 fixation; the aphotic, fully oxygenated, nitrate (NO(-) 3)-rich, waters of the oligotrophic Levantine Basin (LB) and the Gulf of Aqaba (GA). N2 fixation rates measured from pelagic aphotic waters to depths up to 720 m, during the mixed and stratified periods, ranged from 0.01 nmol N...

Abstract. Biogeochemical cycling of carbon (C) and nitrogen (N) in the ocean depends on both composition activity underlying biological communities abiotic factors. The Southern Ocean is encircled by a series strong currents fronts, providing barrier to microbial dispersion into adjacent oligotrophic gyres. Our study region straddles boundary between nutrient-rich gyre southern Indian Ocean, an...