135 research outputs found
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The non-enzymatic formation of nitric oxide from soil and clay systems
Prevailing concepts relating to the non-enzymatic gaseous
loss of nitrite from soil are thought to be inadequate as regards
to the mechanisms involved. The conventional explanation for
nitric oxide formation i.e., the acid decomposition of nitrite,
is held to be insufficient in substrates of only mild or slight
acidity. A criticism is presented wherein it is maintained that
certain past practices in methodology have created rather than
eliminated confusion. Positive suggestions are proposed which
may help to eliminate confusion in future experiments.
Evidence was obtained from soil and clay systems which attest
to a mechanism of loss whereby nitrite may react with certain
metals to yield nitric oxide as a primary gaseous product. A
conventional half-cell reaction is presented wherein a transition-like metal is oxidized and nitrite is reduced to nitric oxide
with the formation of water. It is implied that hydrogen ions
may be necessary--acid conditions favor the reduced state of the
metals which is a more active state with respect to the formation of nitric oxide--for such reactions, but that they are not sufficient
in substrates of only mild acidity.
An apparent corollary to this study is that the very conditions
which favor classical denitrification from nitrate also favor
metal-nitrite reactions. Under such conditions both nitrate and
the metals involved would be expected to undergo reduction resulting
in an increased possibility for nitric oxide formation. This
possibility places in question the status of nitric oxide as a
direct biochemical intermediate in the microbial formation of
nitrogen gas.
It is suggested that a mechanism involving transition -like
metals may account for significant losses of mineral nitrogen
from field soils capable of accumulating nitrite under conditions
of moderate or slight acidity
Bologna guidelines for diagnosis and management of adhesive small bowel obstruction (ASBO) : 2017 update of the evidence-based guidelines from the world society of emergency surgery ASBO working group
Background: Adhesive small bowel obstruction (ASBO) is a common surgical emergency, causing high morbidity and even some mortality. The adhesions causing such bowel obstructions are typically the footprints of previous abdominal surgical procedures. The present paper presents a revised version of the Bologna guidelines to evidence-based diagnosis and treatment of ASBO. The working group has added paragraphs on prevention of ASBO and special patient groups. Methods: The guideline was written under the auspices of the World Society of Emergency Surgery by the ASBO working group. A systematic literature search was performed prior to the update of the guidelines to identify relevant new papers on epidemiology, diagnosis, and treatment of ASBO. Literature was critically appraised according to an evidence-based guideline development method. Final recommendations were approved by the workgroup, taking into account the level of evidence of the conclusion. Recommendations: Adhesion formation might be reduced by minimally invasive surgical techniques and the use of adhesion barriers. Non-operative treatment is effective in most patients with ASBO. Contraindications for non-operative treatment include peritonitis, strangulation, and ischemia. When the adhesive etiology of obstruction is unsure, or when contraindications for non-operative management might be present, CT is the diagnostic technique of choice. The principles of non-operative treatment are nil per os, naso-gastric, or long-tube decompression, and intravenous supplementation with fluids and electrolytes. When operative treatment is required, a laparoscopic approach may be beneficial for selected cases of simple ASBO. Younger patients have a higher lifetime risk for recurrent ASBO and might therefore benefit from application of adhesion barriers as both primary and secondary prevention. Discussion: This guideline presents recommendations that can be used by surgeons who treat patients with ASBO. Scientific evidence for some aspects of ASBO management is scarce, in particular aspects relating to special patient groups. Results of a randomized trial of laparoscopic versus open surgery for ASBO are awaited.Peer reviewe
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Nitrogen Fixation (Acetylene Reduction) Associated with Rhizosheaths of Indian Ricegrass Used in Stabilization of the Slick Rock, Colorado Tailings Pile
Indian ricegrass sown on a sandy soil covering a uranium mine tailings exhibited associative nitrogen fixation (acetylene reduction). Acetylene reduction rates for whole plants varied from 2,100 to 19,500 nm/4 days. Nitrogen fixation was associated with the rhizosheaths. It is suggested that the reclamation of mine tailings in arid climates may be facilitated by stabilizing sandy textured coverings with rhizosheath-forming grasses.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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