Cap carbonate

Mixtures of liquid oxygen with dichloromethane, 1,1,1-trichloroethane, trichloroethylene and chlorinated dye penetrants 1 and T exploded violently when initiated with a blasting cap. Carbon tetrachloride exploded only mildly, and a partly fluorinated chloroalkane not at all. Trichloroethylene has been used for degreasing metallic parts before use with liquid oxygen, but is not safe. 

Stationary phase End-capping Carbon content % Surface area3 m2/g PEOb 104 cm2 V... 

Open a bottle and cover it with a balloon. Put this bottle in the refrigerator. Open a second bottle and put it in a pan of hot water. The balloon on the bottle in the refrigerator should not get as large as the balloon on the bottle in the hot water. The cold temperature makes the molecules move slower and they are less likely to leave the liquid. We cap carbonated drinks and then put them in the refrigerator to keep them from losing carbon dioxide gas. 

In our model, cap carbonates are explained as a result of high carbonate alkalinity in an ice-covered ocean, regardless of the specific mechanism for melting the snowball Earth. Ice could melt for a variety of reasons (e.g., greenhouse gases, a positive perturbation in solar forcing, a decrease in planetary albedo), but cap carbonates are expected to be produced as a result of the transition from high to low oceanic carbonate alkalinity. 

Jiang G, Kennedy MJ, Christie-Blick N (2003) Stable isotopic evidence for methane seeps in Neoproterozoic postglacial cap carbonates. Nature 426 822-826... 

Porter SM, Knoll AH, Affaton P (2004) Chemostratigraphy of Neoprotero-zoic cap carbonates from the Volta Basin, West Africa. Precambrian Res 130 99-112... 

Sankaran AV (2003) Neoproterozoic snowball earth and the cap carbonate controversy. Curr Sci 84 871-873... 

Metal-capped carbon chains can exist in several forms (A-D Chart 1), with uneven-numbered chains only as cumulenic or alkynyl-carbynic tautomers and to date, up to 20 carbon atoms have been used to join two... 

Kennedy M. J., Christie-Blick N., and Sohl L. E. (2001) Are Proterozoic cap carbonates and isotopic excursions a record of gas hydrate destabilization following Earth s coldest intervals Geology 29, 443-446. 

Fig. 6.17 Carbonate isotopic excursions during Neoproterozoic glaciations predicted by the Snowball Earth and gas-hydrate models (after Jacobsen 2001). Zero on the time scale corresponds to onset of cap-carbonate deposition.

This stimulates the precipitation of the cap carbonates. Assuming the DIC (mainly bicarbonate) reservoir was c. 10 Tt (as at present) with a 513C value of 0%o, and that the methane had a mean 813C value of—60%o, the minimum amount of methane required to achieve the required isotopic excursion is c.5 Tt, which is about the estimated quantity of the cap carbonates. There also seem to be sedimentary structures consistent with methane venting (Kennedy et al. 2001). 

Another series of tetranuclear compounds has been basically obtained by adding a ferrocenyl moiety to the tricobalt methylidyne cluster Co3(p3-CHXCO)9 [79, 80]. Fig. 31, which refers to Co3(C (C5H4)-Fe(C5H5) (CO)9, illustrates the main structural features of this class of compounds [80]. With respect to the symmetrical assembly of Co3(CH)(CO)9 [81], the presence of the sterically encumbering ferrocenyl substituent induces deformation from C3v symmetry displacing the capping-carbon atom towards one cobalt vertex. 

A simple macrobicycle can be considered to arise by addition of another chain or strap of atoms to a macromonocycle, to provide three chains joined at two capping carbon atoms (top), effectively two fused macromonocycles. This example offers six donor groups to a metal ion, as exemplified with ball and stick and space-filling models the latter shows the small central cavity able to accommodate only a single cation. These readily form very stable octahedral complexes with a range of metal ions the best-known example has L = NH (called sarcophagine ). 

The carbon onions present a Unk between the fullerenes and the multiwalled nanotubes. From one point of view, they may be considered fullerene cages concentrically contained one inside another and constantly increasing in size toward the outside. On the other hand, they might just as weU be interpreted as multiwalled nanotubes with length zero so only the caps of the constituent tubes remain. With irregular caps, carbon nanoparticles of uneven shape result. 

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