Improvement in flow-sheet of extraction chromatography for trivalent minor actinides recovery

Journal of Radioanalytical and Nuclear Chemistry - Extraction chromatography flow-sheet employing octyl(phenyl)-N,N-diisobutylcarbonoylmethylphosphine oxide and bis(2-ethylhexyl) hydrogen phosphate...     

D3h‐Symmetric Porphyrin‐Based Rigid Macrocyclic Ligands for Multicofacial Multinuclear Complexes in a One‐Nanometer‐Sized Cavity

The one‐step synthesis of D_3h‐symmetric cyclic porphyrin trimers 1 composed of three 2,2′‐[4,4′‐bis(methoxycarbonyl)]bipyridyl moieties and three porphyrinatozinc moieties was achieved from a nickel‐mediated reductive coupling of meso‐5,15‐bis(6‐chloro‐4‐methoxycarbonylpyrid‐2‐yl)porphyrinatozinc. Although cyclic trimers 1 were obtained as a mixture that included other cyclic and acyclic porphyrin oligomers, an extremely specific separation was observed only for cyclic trimers 1 when using columns of silica gel modified with pyrenylethyl, cyanopropyl, and other groups. Structural analysis of cyclic trimers 1 was carried out by means of NMR spectroscopy and X‐ray crystallography. Treatment of an η³‐allylpalladium complex with a cyclic trimer gave a tris(palladium) complex containing three η³‐allylpalladium groups inside the space, which indicated that the bipyridyl moieties inside the ring could work as bidentate metalloligands.     

Novel and stereocontrolled asymmetric synthesis of a new naturally occurring styryllactone, (+)-cardiobutanolide

An efficient and stereodefined strategy is described for the asymmetric synthesis of a new styryllactone from the stem bark of Goniothalamus cardiopetalus, cardiobutanolide. The synthetic process is based on requisite manipulation of the functionalized bicyclic lactol-lactone intermediate incorporating the glucuronolactone-derived skeleton in a complete stereoselective manner.     

Rugged distal tips for CO2 laser medicine

Low-loss and rugged distal tips for CO₂ laser have been proposed and fabricated based on a commercially available stainless steel (St) pipe. A method of smoothening the inner surface of the St pipe with a rough inner surface is put forward. Fabrication parameters, transmission properties, and mechanical strength of the cyclic olefin polymer-coated silver hollow St distal tip are experimentally discussed.     

Calculation of heat transfer and uniformity of chemical amplification during post-exposure bake

Heat transfer in a resist-coated silicon wafer using a bake process is theoretically evaluated by modeling the three-dimensional diffusion process, focusing on the controllability of the lithographic performance of chemically amplified resists. Six models of various ambient conditions are used. The proximity gap between the hotplate and the wafer is found to have a dominant influence on the heat transfer process for the whole system. Because the atmosphere near the wafer acts as a thermal diffusion buffer layer, no temperature gradient occurs in the resist, even when it is subjected to convective heat transfer from the resist surface. Experimental results obtained by X-ray lithography confirm the calculation results.     

A SAXS study of the nanometer scale hybrid structure of Si---Ti---C---O amorphous fibers

A small-angle X-ray scattering (SAXS) study was performed to reveal the nanometer scale hybrid structure of Si---Ti---C---O fibers prepared by the pyrolysis of polytitanocarbosilane. The SAXS profile for Si---Ti---C---O fibers is attributed to two different types of scattering entities: an anisotropic contribution from long filaments with diameters hundreds to thousands of Ångströms and an isotropic contribution from β-SiC fine clusters of about a nanometer in diameter. A drastic degradation in the tensile strength of the fibers is correlated to the characteristic variations in their long-and medium-range structure.     

Major-to-ultratrace elements in bone-marrow fluid as determined by ICP-AES and ICP-MS.

The major-to-ultratrace elements in human bone-marrow fluid were determined by ICP-AES (inductively coupled plasma atomic emission spectrometry), and ICP-MS (inductively coupled plasma mass spectrometry). The bone-marrow fluid sample was centrifuged prior to acid digestion to exclude the bone piece from bone marrow, and then digested with nitric acid. As a result, 20 elements could be determined over the concentration range from 1610 microg g(-1) for Na to 0.00043 microg g(-1) for W. It was found that Fe, Zn and Sb were enriched by ca. 264-, 7- and 15-fold, respectively, in bone-marrow fluid, compared to those in human blood serum. Alkali metals (K, Rb, Cs), except for Na, were also significantly enriched in bone-marrow fluid. Furthermore, the concentrations of various elements, such as Fe, P, Al, Zn, Cu, Se, Zr, Sn, Ag and W, were significantly higher than those in open seawater.     

Macromolecular synthesis from saccharic lactones. Ring-opening polyaddition of D-glucaro- and D-mannaro-1,4:6,3-dilactones with alkylenediamines

Ring-opening polyaddition of a saccharic acid dilactone prepared from D-glucose, D-glucaro-1,4 : 6,3-dilactone, with several alkylenediamines proceeded at room temperature with no catalyst. The resulting new polyamides carrying many pendant hydroxyl groups, poly(alkylene D-glucaramide)s, were more amorphous and hydrophilic than the corresponding nylons having no hydroxyl groups, and were hydrolyzed more easily than the latter in an acidic condition. The ring-opening ability of D-mannaro-1,4:6,3-dilactone, which was another saccharic acid dilactone obtained from D-mannitol, was found to be lower than that of the D-glucaric analogue. © 1993 John Wiley & Sons, Inc.