The role of root-specific clavata1 homologues in regulation of cell differentiation within the arabidopsis root meristem

Ziel

Research objectives and content

mechanisms of chlorine atoms, hydroxyl radical and nitrogen trioxide with a variety of fluorinetd ethers, which may be used as potential alternatives of fully halogenated hydrocarbons. Under tropospheric conditions, fluorinated ethers will react with hydroxyl radicals, mainly via the abstraction of a hydrogen atom. Preliminary investigations have also indicated that chlorine atoms are probably significant in the degradation of partially halogenated ethers, and proceed with a greater or even comparable rate than hydroxyl radicals. Therefore, the values of their rate constants have to be determined in order to evaluate the importance of these compounds with respect to ozone depletion and greenhouse warming effect. We propose to study the gas phase reactions of chlorine atoms, hydroxyl radicals and nitrogen trioxide with partially fluorinated ethers, CF2HOOCHF2, CF30CHF2, CF3CH20CH3, CF3CH20CHF2, CF3CF3CH20CH2CF3 and CHF2CF20CH=CH2, which are commercially available. They do not contain chlorine or bromine which could be released and enter the ozone destruction cycle. The degree of fluorination in these modules is expected to affect the rate and temperature dependence of their reactions with halogen atoms. The main concerns of the proposed study are the reaction rate with halogen atoms and its temperature dependence at ordinary temperatures (-20 - +100
c). The specific reactivity of substituted alkyl groups towards halogen atoms and its relationship with molecular structure will also be evaluated. The main objectives concerning the oxidation processes of partially fluorinated ethers are: 1. Determination of the reaction rate constants of Cl, OH, and NO3 with a series of fluorinated ethers in the gas phase over the temperature range 273-400 K. This will provide information about the initial steps in the oxidation pathway. 2. Information about primary reaction channels and the position of the initial attack on ethers by the radicals. 3. Evaluation of the degradation mechanisms of fluorinated ethers under atmospheric conditions.

Wissenschaftliches Gebiet

Programm/Programme

FP4-TMR - Specific research and technological development programme in the field of the training and mobility of researchers, 1994-1998

Thema/Themen

0301 - Post-graduate research training grants

Aufforderung zur Vorschlagseinreichung

Data not available

Finanzierungsplan

Data not available

Koordinator

Rijksuniversiteit Utrecht

EU-Beitrag

Keine Daten

Adresse

1,Yalelaan
3508 TD Utrecht
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