Continuous non-destructive determination of nitrogenase activity in microbial cultures

1975 ◽  
Vol 21 (7) ◽  
pp. 980-983 ◽  
Author(s):  
T. A. Larue ◽  
W. G. W. Kurz ◽  
C. Mallard
Keyword(s):  
Gas Chromatography ◽  
Gas Flow ◽  
Nitrogenase Activity ◽  
Microbial Cultures ◽  
Non Destructive

The dinitrogen fixing enzyme nitrogenase (nitrogen:(acceptor) oxidoreductase) (EC 1.7.99.2) is monitored by its ability to reduce acetylene to ethylene. Low, non-inhibitory concentrations of acetylene (~10−7 mol/litre) are mixed with the gas flow aerating microbial cultures, and acetylene and ethylene in the effluent gas are determined by gas chromatography. The procedure is safe, simple and is carried out in situ without disturbing the growing culture. Transient changes in nitrogenase activity are easily detected. The technique may be automated.

Bohrwiderstandsmessungen, eine neue und standardisierbare Methode zur Bestimmung der Kohäsion von Naturstein: Entwicklung eines Prototypes und dessen Erprobung / Drilling force measurement system, a new standardisa i methodology to determine the stone cohesion: Prototype design and validation

2000 ◽  
Vol 6 (2) ◽  
pp. 115-132 ◽  
Author(s):  
P. Tiano ◽  
C. Filareto ◽  
S. Ponticelli ◽  
M. Ferrari ◽  
E. Valentini
Keyword(s):  
Force Measurement ◽  
Direct Determination ◽  
Drilling Force ◽  
System A ◽  
Stone Materials ◽  
Force Measurement System ◽  
Drilling Resistance ◽  
Non Destructive

Abstract In the field of conservation of monumental buildings actually a standard methodology is lacking, with which it is possible to determine with the same sensitivity and reliability the "stone hardness" both at the superficial surface and at larger depths (few centimetres), both in laboratory and in situ. The use of the drilling resistance to determine the stone hardness is a very recent application and few working outdoor devices exist. The objective of this work is to validate a new and improved system to assess the drilling resistance of stones. The DFMS is portable and a quasi non-destructive device for direct determination of the "cohesion" of stone materials through the determination of their drilling resistance. The best operational features of the prototype have been established together with the assessment of the sensitivity and reliability of the system.

Rapid determination of emerging contaminants in water and herbal infusions by in situ derivatization and gas chromatography-tandem mass spectrometry

2015 ◽  
Vol 7 (7) ◽  
pp. 3006-3014 ◽  
Author(s):  
Beatriz Albero ◽  
Consuelo Sánchez-Brunete ◽  
Esther Miguel ◽  
José L. Tadeo
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Emerging Contaminants ◽  
Rapid Determination ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Herbal Infusions ◽  
In Situ Derivatization

A simple and rapid method is proposed for the determination of fourteen emerging contaminants in water and different herbal infusions (tea, chamomile, linden-blossom and pennyroyal).

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