The kinetically effective stoichiometry of reactions in the carbon-sulphur dioxide system

1973 ◽  
Vol 26 (4) ◽  
pp. 723 ◽  
Author(s):  
JD Blackwood ◽  
DJ McCarthy

The kinetically effective stoichiometry of reactions resulting from contacting carbon and sulphur dioxide at elevated temperatures involves the five overall reactions: 2C + 2SO2 → 2CO2 + S2 C+ S2 + CO2 → 2COS C+ 2COS → CS2 + 2CO C+ COz -, 2C0 C+S, -+ CS, The rates of the two reactions forming carbon disulphide are shown to have similar temperature dependence in the range 800-950�C, while the carbon-carbon dioxide reaction is shown to be more temperature sensitive than the carbon-carbonyl sulphide reaction in the same temperature range. The existence of parallel routes for carbon disulphide formation was detected by using a mechanistic argument to remove the redundancy in the system where carbon disulphide was concerned.

Development ◽  
1992 ◽  
Vol 114 (3) ◽  
pp. 787-796 ◽  
Author(s):  
H.J. Bellen ◽  
D. D'Evelyn ◽  
M. Harvey ◽  
S.J. Elledge

We have isolated temperature-sensitive diphtheria toxins (DT-A(ts)) to develop a method that allows temporal impedement of cellular functions. Four DT-A(ts) genes were isolated in a mutagenesis screen using the yeast, Saccharomyces cerevisiae. When expressed in yeast, these DT-A(ts) arrest growth at 18 degrees C but not at 30 degrees C. Three DT-A(ts) were subsequently tested in the R1-R6 photoreceptor cells of transgenic fruit flies, Drosophila melanogaster. The toxins show similar temperature dependence in both organisms, suggesting that they may be useful in a wide range of non-homeothermic species. DNA sequence analysis revealed that three of the four DT-A(ts) mutations are novel. Interestingly, the fourth DT-A(ts) carries the same point mutation as the extensively characterized CRM197, an ADP ribosyltransferase-defective form of diphtheria toxin.


The symmetrical linear structure of both carbon dioxide and carbon disulphide is now well established. Recent developments in theory make it highly probable that a complete explanation of the Raman and infra-red spectra of these substances, with the concomitant selection rules, will shortly be available. It is in the meantime of consequence to examine the absorption spectrum of carbonyl sulphide, since the chemical and external physical properties of this molecule are intermediate to those of the other two, though the lack of symmetry in its structure predicts more complex intramolecular relationships. No previous determination of this spectrum appears to have been made. Experimental . Carbonyl sulphide was prepared by dropping sulphuric acid (5 parts of acid to 4 of water by volume) on to potassium thiocyanate in a flask maintained at 21° C. by means of a water bath. The chief impurities generated in the reaction are carbon disulphide, carbon dioxide, and carbon monoxide* ; the gaseous product was led firstly through a trap immersed in a freezing mixture of salt and ice, secondly through a bubbler containing a 33 per cent, solution of potassium hydroxide, thirdly through a tube of active charcoal, fourthly through calcium chloride, and finally, through a trap immersed in a saturated solution of carbon dioxide snow in acetone, to the fume cupboard v en t; glass to glass seals were used throughout. The traps and tubes removed in succession the major portion of the carbon disulphide, the carbon dioxide, the remaining carbon disulphide, and the water vapour ; carbonyl sulphide boils at —50° C. and was condensed in the last trap at a temperature of —78°, any carbon monoxide passing on unabsorbed. When sufficient of the required substance had been collected, the trap was disconnected from the generating apparatus and connected to the absorption tube system, where the gas was transferred to an evacuated aspirator and stored over phosphoric oxide. The aspirator was totally enclosed to obviate possible decomposition of the carbonyl sulphide by light.


1990 ◽  
Vol 64 ◽  
pp. 143-159 ◽  
Author(s):  
L. Nemeth ◽  
G. Gati ◽  
A. Gervasini ◽  
A. Auroux ◽  
G. Mink ◽  
...  

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