Carbon fourteen

There are 19 S-compounds which have been identified in Shiitake mushrooms (Table II), and Figure 2 shows the structures of these compounds. These S-compounds can be classified into 4 major groups, containing 1, 2, 3 and 6 carbons. Fourteen out of the 19... 

Atoms of a given element that differ in the number of neutrons, and consequently in mass, are called isotopes. The symbol C or simply (read "carbon twelve," carbon-12) represents the carbon atom with six protons and six neutrons. The number of protons, which is called the atomic number, is shown by Ihe subscript. The atomic number of each element is listed witii the name and symbol of Ihe element on the front inside cover of tire text. Because all atoms of a given element have the same atomic number, tire subscript is redundant and hence is usually omitted. The superscript is called tire mass number it is Ihe total number of protons plus neutrons in the atom. Some carbon atoms, for example, contain six protons and eight neutrons and are consequently represented as (read "carbon fourteen"). Several isotopes of carbon are listed in Table 2.2 T. 

Though these substances are not monocyclic like benzene—and Hiickel s rule should not, strictly, apply to them—the introduction of the transannular bond, that makes them bi- and tricyclic, respectively, seems to cause relatively little perturbation, so far as delocalisation of the n electrons over the cyclic group of ten or fourteen carbon atoms is concerned. 

Fall has studied the capability of fourteen species of microorganisms to grow on methoprene as sole carbon source. One of these organisms, Cladosporium resinae, was able to utilize methoprene as sole carbon source, while another. Pseudomonas citronellolis, was similarly able to utilize 7-methoxycitronellic acid. (41). 

Although no adverse effects have been reported in the literature among workers exposed to calcium carbonate, high concentrations of the dust would be expected to act as a physical irritant to the eyes and skin. Fourteen British workers exposed to heavy calcium carbonate concentrations for 12-35 years showed no trace abnormalities due to dust or any clinical sign of pneumoconiosis or chronic bronchitis on X ray. Long exposure to high dust concentrations of pure calcium carbonate (quartz content less than 1.1%) did not result in lung fibrosis. 

The new product, which they named radionitrogen, was a hitherto unknown radioactive isotope of ordinary nitrogen. It disintegrates with a half period of fourteen minutes and expulsion of positrons, forming a stable, inactive isotope of carbon ... 

These products, prepared from highly paraffinic fractions averaging about fourteen carbon atoms per molecule, are synthesized according to the reactions ... 

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