Eosin reagent

Abe R, Hara K, Sayama K, Domen K, Arakawa H (2000) Steady hydrogen evolution from water on Eosin-Y-fixed Ti02 photocatalyst using a silane coupling reagent under visible light irradiation. J Photochem Photobiol A Chem 137 63-69... 

Parenchymal cells (PC), or hepatocytes, originate from epithelial cells and represent most of the total number of liver cells (65%). Because of their relatively large size, hepatocytes are microscopically clearly visible after staining liver sections with hematoxylin and eosin (HE). Also, the hepatocytes store glycogen, which can be identified histochemically with periodic acid-Schiff (PAS) reagent. The hepatocytes are primarily responsible for the uptake of endogenous products and xenobiotics at the sinusoidal membrane of the cell and their subsequent metabolism and excretion into bile by means of the canalicular membrane. 

For light microscopy, tissues are fixed and embedded in paraffin. Sections are stained with hematoxylin and eosin, and periodic acid Schiff s reagent. Twenty glomeruli are examined per rat and number of glomeruli with injury (crescent formation) are determined. 

Fluorescein test Free bromine converts the yellow dyestuff fluorescein(I) into the red tetrabromofluorescein or eosin(II). Filter paper impregnated with fluorescein solution is therefore a valuable reagent for bromine vapour since the paper acquires a red colour. 

Chlorine tends to bleach the reagent. Iodine forms the red-violet coloured iodo-eosin and hence must be absent. If the bromide is oxidized to free bromine by heating with lead dioxide and acetic acid, practically no chlorine is simultaneously evolved from chlorides, and hence the test may be conducted in the presence of chlorides. 

It was originally thought that lead azide existed in two allotropic forms a and 0 (VoL 111, p. 169). Now it is accepted that tlie substance is polymorphic and exists in four forms o, 0, y and 6. The a-orthorhombic is the only one acceptable for technical application. It is the main product of precipitation with traces of the other forms present [89]. The monoclinic jS-fomi is stable when dr>. but recrystallizes as the a-form. Tlie presence of some organic dyes (e.g. eosin) enhances the fomiation of form and hydrophile colloids inhibit its formation. Breaking a needle of Torm may produce an explosion (contrary to the views of some authors Vol. Ill, p. 173). The monoclinic y-form is less stable than a and jS [90]. It can be obtained from pure reagents at pll 3.5—7.0 or in the presence of vinyl alcohol. The triclinic 6-form precipitates from pure reagents at pH values of between 3.5 and 5.5 [90]. Both forms yand 6 are usually precipitated simultaneously and can be separated (with care ) by hand. 

The acid xanthene dyes comprise Eosin (tetrabromofluorescein, formula 4.34) [79,80], Erythrosin (tetraiodofluorescein) and Rose Bengal B (formula 4.35) [79]. All these reagents are available as sodium salts. 

Lead azide exists as four polymorphic forms [287] of which the orthorhombic oc-lead azide is the most stable [276]. In fact, a-lead azide is the only acceptable form for technological applications. Presently, the state of the art of making the polymorphs can be summarized as follows a-lead azide is the main product of precipitation, with traces of the other forms present [288]. The monoclinic [276] /3-form is stable when dry, but re crystallizes as the a-form [276,289]. The presence of organic dyes (eosin, neutral red) at the precipitation enhances formation of /3-lead azide [276] the presence of hydrophile colloids inhibits it [276,287]. The monoclinic [287] 7-form, apparently less stable than a and /3 [289], is obtained from pure reagents at a pH of 3.5-7 [287] or in the presence of polyvinyl alcohol [289]. The triclinic 6-form precipitates from pure reagents between pH 3.5 and 5.5 [287]. No method is presently available to yield a single polymorph exclusively, but the crystals differ sufficiently in shape to allow hand selection under the microscope [287,288]. 

Disulfides play a prominent role in pharmaceuticals, pesticides, and rubber vulcanization reagents. In biological systems, disulfide bonding is essential for peptides and proteins to fold into their active conformation. Noel et al. reported a mild batch and continuous-flow method to access disulfides by the aerobic oxidation of thiols [48]. Initially, an open flask batch procedure with Eosin Y (1 mol%) as catalyst resulted in near quantitative yields for a variety of thiophenols and heteroaromatic and aliphatic thiols, within 16 h. Moreover, it was found that the... 

It is known, however, that isothiocyanates on their own can form stable self-assembled monolayers on gold (Section V.E), and amine-terminated monolayers were reported to show unusually low reactivity towards electrophilic reagents . It is therefore possible that the observed immobihzation of eosin is due not to reaction with amino groups, but to either insertion of the eosin isothiocyanate into a disordered layer of cysteamine, or even replacement of cysteamine monolayer with the molecules of S=C=N—eosin. Because the experimental data on reactions in gold-thiol monolayers are scarce, chemical transformations described in this section should be interpreted with some caution. 

There are some liquid-phase CL methods using dye compounds as a reagent. Ozone can be measured either by passing sample air into an ethanolic solution of rhodamine B and gallic acid or using a rhodamine B impregnated silica disk. CL methods with eosin Y and with coumarin 47 are also reported for rapid... 

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