Hydrogen concentration determination

The hydrogen concentration determines the competition between this so-called halorespiration and methanogenesis. Acetotrophic bacteria such as Desulfitobacterium sp. are associated with incomplete dechlorination to cis-DCE while Dehalococcoides sp., which are hydrogenotrophic, are associated with complete dechlorination to ethene (Yang et al., 2005). 

Figure 14. Comparison of hydrogen concentrations determined chemically with those determined by FTIR. Key 0 subbituminous coals, lignites, and products and X> bituminous coals and products.

Hydrogen concentration determination 98 3. Second generation switchable mirrors 226... 

Conditions of hydrogenation also determine the composition of the product. The rate of reaction is increased by increases in temperature, pressure, agitation, and catalyst concentration. Selectivity is increased by increasing temperature and negatively affected by increases in pressure, agitation, and catalyst. Double-bond isomerization is enhanced by a temperature increase but decreased with increasing pressure, agitation, and catalyst. Trans isomers may also be favored by use of reused (deactivated) catalyst or sulfur-poisoned catalyst. 

Only acids are sour. Sourness is not identical to chemical acidity or pH, which is a function of the hydrogen ion concentration, but also appears to be a function of the entire acid molecule. A combination of pH and acid concentration determines the actual degree of the sour taste. At the same pH, any organic acid, eg, citric acid, exhibits a far greater sourness than a mineral acid, eg, hydrochloric acid (27,28). 

Fig. 20.6 Electrocapillary curves for HCI at various concentrations determined using a reversible hydrogen electrode (R.H.E.) immersed in the same concentration of HCI as that used for the determination (after Bockris and Reddy )...

The gamma ray yield is proportional to the local hydrogen content, which can therefore be determined. The hydrogen concentration is given by... 

Figure 18. Depth profiles of hydrogen from polyimide (PI) implanted with 100 keV Kr ions to the fluences indicated. The horizontal line shows the hydrogen concentration in pristine PI. The profiles were determined from ERDA measurement performed with 2 MeV alpha particles [122]. The depth resolution was about 50 nm. It is seen that significant H depletion starts at the fluence of about IxlO " cm. ...

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