The conversion technique enables the immediate loading of implants using an existing or a new complete denture. Acrylic resin is generally used directly intraorally when the conventional conversion technique is used. The technique described suggests picking-up the interim copings and capturing the soft tissue contour with the conversion prosthesis with a polyether impression material when 4 imp...

The absolute configuration of gymnocin-B has been determined to be (S)-10 and (S)-37. Three challenges toward the configurational assignment of this largest of the polyether marine toxin include (i) introduction of p-(meso-triphenylporphyrin)-cinnamate group (TPPcinnamate) on sterically hindered 10-, 37-hydroxyls under mild conditions, (ii) conformational analysis in the presence of TPPcinnamat...

The discovery of the crown ethers stemmed from efforts to control the catalytic activity of vanadium and copper by complexation with multidentate ligands. The first crown ether, 2,3,11,12-dibenzo-1,4,7,10,13,16-hexaoxacyclo-octadeca-2,11-diene, was obtained in 0.4% yield during an attempt to prepare a phenolic ligand from catechol and bis(2-chloroethyl)ether. This compound, which complexed with...

The structural features of polycyclic polyether natural products can, in some cases, be traced to their biosynthetic origin. However in case that are less well understood, only biosynthetic pathways that feature dramatic, yet speculative, epoxide-opening cascades are proposed. We summarize how such epoxide-opening cascade reactions have been used in the synthesis of polycyclic polyethers (see s...

In addition to the 5'-phosphate ester on its flavin mononucleotide (FMN) moiety, flavodoxin from Azotobacter vinelandii contains 2 moles of tightly bound phosphate. One non-coenzyme phosphate group is covalently bound to the protein, as it remains with the protein on acid precipitation, whereas the other phosphate is released. The invariance of the (31)P nuclear magnetic resonance chemical shif...

Glutathione monoesters in which the carboxyl group of the glycine residue is esterified were previously found, in contrast to glutathione itself, to be effectively transported into various types of cells and to be converted intracellularly into glutathione. Glutathione monoesters are thus useful for prevention of oxidative stress, certain toxicities, and for treatment of glutathione deficiency....

BACKGROUND The introduction of different interocclusal recording materials has put clinicians in dilemma that which material should be used in routine clinical practice for precise recording and transferring of accurate existing occlusal records for articulation of patient's diagnostic or working casts in the fabrication of good satisfactory prosthesis. In the era of developing world of dentist...

Desorption or evaporation is one of the mechanisms for loss of perfluoropolyalkylether (PFPE) lubricants from the surfaces of data storage media. One approach to minimizing PFPE loss to desorption is the use of lubricants with increasing molecular weight or increasing average chain length. In order to understand the effects of chain length on the lubricant evaporation kinetics we have studied t...

A new polyether antibiotic, lonomycin, was isolated from the culture of Streptomyces ribosidifcus strain TM-481. The antibiotic obtained as a sodium salt is a colorless prism having a molecular formula of C44H75O14Na(M.W. 850), m.p. 188 approximately 189 degrees C, and has no absorption maxima in the ultraviolet region. The infrared and NMR spectra of the antibiotic suggest the presence of a ca...