A polypyrrolic macrocycle with naphthalenyl linkers between the N(4)-donor compartments (L(2)) was designed theoretically according to its experimentally-known analogues with phenylenyl (L(1)) and anthracenyl (L(3)) linkers. The uranyl and bis(uranyl) complexes formed by this L(2) ligand have been examined using scalar-relativistic density functional theory. The calculated structural properties...

Nano-resolution fluorescence electron microscopy (nano-fEM) pinpoints the location of individual proteins in electron micrographs. Plastic sections are first imaged using a super-resolution fluorescence microscope and then imaged on an electron microscope. The two images are superimposed to correlate the position of labeled proteins relative to subcellular structures. Here, we describe the meth...

Spinach chloroplast lamellae were stained with aqueous uranyl acetate immediately after glutaraldehyde-osmium fixation but before dehydration and embedding. Under these conditions, the lamellae are shown in thin sections to have 95-A x 115-A coupling factor particles on their surfaces. The particles can be seen only on the matrix side of nonopposed thylakoids, and are shown to occur on both str...

In the elastogenesis in the periodontal tissue, microfibrils in the bundle are linked to one another through delicate filaments found as the deposition of high electron-density. The elastic fiber system in the periodontal ligament is characterized by the presence of only oxytalan fibers composed of numerous microfibrils without the central core. In contrast, elaunin fibers are distinguished fro...

A novel dry synthesis for the uranium(VI) dioxodiacetohydroxamate (UAHA) complex has been developed. The complex was generated in > 80% yield by mechanically grinding solid uranyl acetate dihydrate (UAc) with solid acetohydroxamic acid in stoichiometric amounts. The resulting UO2(AHA)2 ·4H2O solid is purified by washing with acetone. The stoichiometry was confirmed via colorimetric assays for U...

Nucleic acids in young leaves of Swiss chard have been studied by light and electron microscope techniques. Leaf DNA has also been characterized by density gradient centrifugation and shown to contain a minor band of higher guanine plus cytosine (GC) content, presumably attributable to chloroplasts. The chloroplasts were faintly stained by the Feulgen reaction; radioautography demonstrated the ...

In view of the increasing importance of acid-base equilibrium and of the r81e of the inorganic elements in the body economy, the accurate determination of sodium in the blood and body fluids becomes of increasing importance. Barber and Kolthoff (1) in 1928 were the first to employ the triple salt, uranyl zinc sodium acetate, for the quantitative determination of sodium. They ascribed to t,his s...

In order to evaluate uranyl photocleavage as a tool to identify and characterize structural and dynamic properties in RNA, we compared uranyl cleavage sites in five RNA molecules with known X-ray structures, namely the hammerhead and hepatitis delta virus ribozymes, the P4-P6 domain of the Tetrahymena group I intron, as well as tRNA(Phe) and tRNA(Asp) from yeast. Uranyl photocleavage was observ...

Uranyl-carboxyl-ate hybrid materials dominate the catalog of uranyl compounds owing in part to the affinity between COO(-) functional groups and UO2 (2+). Polycarboxyl-ate organic ligands may present a degree of steric hindrance and could thus influence the resulting uranyl topology. Single crystals of the title compound, {(NH4)2[(UO2)2(C12O12)(H2O)2]} n , were synthesized hydro-thermally as a ...

The title compound, [(UO(2))(2)Cl(2)(OH)(2)(H(2)O)(4)], was obtained unintentionally as the product of an attempted reaction between uranium(VI) oxide dihydrate, UO(3)·2H(2)O, and hydrogen bis-(trifluoro-methyl-sulfon-yl)imide (HTf(2)N), in an experiment to obtain crystals of uranyl bis-(trifluoro-methyl-sulfon-yl)imide, UO(2)(Tf(2)N)(2)·xH(2)O. The structure consists of neutral dimers of urany...