Iodinated contrast

As was the case for the monofluoro series, halogens attached directly to the CF2 carbon deshield the fluorine nuclei (Tables 4.2 and 4.3). Iodine has the greatest deshielding effect on fluorine chemical shifts I > Br > Cl > F. In contrast, iodine has its usual shielding effect upon carbon chemical shifts. When considering proton chemical shifts for the fluoromethanes, again one must keep in mind the significant solvent effects observed for all di- and trihalomethanes. 

In contrast, iodine is readily lost from PbXI-cement (see Figure 6). When the concrete was prepared, the cement mixture turned purple suggesting release of elemental iodine, which in the alkaline environment of the cement, disproportionates to iodide and iodate. 

Suprisingly, the use of iodine in an attempted iodocarbamoylation of a DHP led instead to the benzimidazolium salt 279 in contrast, iodine monochloride (ICl)... 

Two derivatization methods for AAs based on the halogenation of the aromatic ring are presented. Bromination yields brominated anilines, in which all hydrogens in ortho- and para-positions are replaced by bromine via an electrophilic substimtion. In contrast, iodination yields the corresponding iodobenzenes, in which all amino groups are substimted by iodine. Derivatization is... 

Studies using synthetic peptides show that iodine atoms on the primary hormonogenic sites are secondary to the influence of amino acid composition in inducing EAT. In contrast, iodine added to tyrosyls on other Tg peptides may have enhancing, neutral, or suppressive effects on their EAT-inducing capacity. 

Americium-241 is used in smoke detectors. It has a first order rate constant for radioactive decay of k = 1.6 X 10" yr . By contrast, iodine-125, which is used to test for thyroid functioning, has a rate constant for radioactive decay otk = 0.011 day", (a) What are the half-lives of these two isotopes (b) Which one decays at a faster rate (c) How much of a 1.00-mg sample of each isotope remains after 3 half-lives (d) How much of a 1.00-mg sample of each isotope remains after 4 days ... 

Iodine excretion in non-pregnant control women was 73.3 ig/g in summer and 98.2 ig/g in winter. In contrast iodine excretion in antibody -ve postpartum women ranged between 50 and 70 ig/g - bordering on values seen in iodine deficiency (6). 

Polyether compounds form stable adducts with iodine, a property which has led to their use as iodophores for bactericides on human and animal skin. For medical applications, iodide concentration is kept low, since the triiodide ion has little disinfecting activity compared to iodine. By contrast, iodine-based analytical methods for surfactant determination are usually conducted in the presence of a large excess of pxjtassium iodide. The likely mechanism consists of the K" -p)olyether complex associating with the large, lipophilic, triiodide anion. The absorbance maximum of the complex is shifted from that of triiodide... 

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