cyanobacteria were collected and identified in five paddy fields with different soil textures of golestan province in iran. it was determined that nostoc ellipsosporum and nostoc muscorum were dominant in all sites among 20 species. to assess the ability of atmospheric nitrogen fixation by the species, their pure cultures were provided by growing on bg-11 solid culture medium. subsequently, eac...

salinity is among important soil stresses adversely affecting the process of nitrogen (n) fixation in leguminous plants in different parts of the world. it has been indicated that salinity can inhibit the early stages of nodulation process between bacterium and the host plant including the exchange of signal molecules (nod gene inducers). there has not been any research regarding the effects of...

  Background: Ligament reconstruction is a common procedure in orthopedic surgery. Although several popular techniques are currently in use, new methods are proposed for secure fixation of the tendon graft into the bone tunnel. Purposes: We sought to introduce our new technique of Bashti bone plug for fixation of soft tissue graft in anterior cruciate ligament (ACL) reconstruction and to compar...

background: ligament reconstruction is a common procedure in orthopedic surgery. although several popular techniques are currently in use, new methods are proposed for secure fixation of the tendon graft into the bone tunnel. purposes: we sought to introduce our new technique of bashti bone plug for fixation of soft tissue graft in anterior cruciate ligament (acl) reconstruction and to compare ...

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 ...

conclusions closed reduction and hybrid external fixation can be used as a definitive treatment for severe comminuted fractures of the distal femur and proximal tibia, when the concomitant contusion of the skin and soft tissue damage prohibits safe open reduction and internal fixation. patients and methods in a prospective study, 44 patients with comminuted fractures of the distal femur or prox...

Biological nitrogen (N) fixation is the primary source of “new” N to unmanaged ecosys­ tems, and recent analyses suggest that terrestrial N inputs via free-living N fixation may be more impor­ tant than previously assumed. This may be particularly true in some tropical rain forests, where free-living fixation could outpace symbiotic N fixation to repre­ sent the dominant source of new N inputs....

Symbiotic nitrogen (N) fixing trees are absent from old-growth temperate and boreal ecosystems, even though many of these are N-limited. To explore mechanisms that could select against N fixation in N-limited, old-growth ecosystems, we developed a simple resource-based evolutionary model of N fixation. When there are no costs of N fixation, increasing amounts of N fixation will be selected for ...

Biological nitrogen fixation (BNF) is the major natural process of nitrogen (N) input to ecosystems. To understand how plant invasion and N enrichment affect BNF, we compared soil N-fixation rates and N-fixing microbes (NFM) of an invasive Spartina alterniflora community and a native Phragmites australis community in the Yangtze River estuary, with and without N addition. Our results indicated ...