The sensitivities of oligosaccharide derivatives in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) were compared using two matrixes, 2,5-dihydroxybenzoic acid (DHBA) and alpha-cyano-4-hydroxycinnamic acid (CHCA). For this purpose, maltopentaose was tagged with 2-aminopyridine (PA), 4-aminobenzoic acid ethyl ester (ABEE), and trimethyl-(p-aminophenyl)ammonium chloride (TMAPA). DHBA was more advantageous for enhancement than CHCA. Among the derivatives, the sensitivity with the PA-tagged maltopentaose showed a 100-fold improvement over the native one with DHBA as a matrix, while the oligesaccharide derivatized with ABEE and TMAPA gave 30- and 10-fold increases in sensitivity over the underivatized one. To obtain structural information from these derivatized oligosaccharides, postsource decay (PSD) during flight in the field-free drift in MALDI-TOFMS was measured. Predictable and reproducible fragmentation patterns could be obtained in all cases. Furthermore, we found matrix-dependence fragmentation with the PA-labeled oligosaccharide. With CHCA, a simple spectrum ascribable to Y series ions was obtained. On the other hand, both B and Y series ions were clearly observed in the DHBA case. The results demonstrate the usefulness of derivatives for sensitive analysis of oligosaccharides with MALDI.

Mass spectrometric methodologies which use electrospray ionization (ESI) for oligosaccharide structural determination and which are linked to classical procedures, such as reductive amination, have been established. Several derivatives of a model oligosaccharide were prepared and their ionization efficiencies in electrospray ionization (ESI) and fast-atom bombardment (FAB) mass spectrometry were investigated. The trimethyl-(p-aminophenyl)ammonium (TMAPA) derivatives showed extremely high sensitivity in positive-ion ESI-MS and gave Y- and Z-series sequence ions by ESI tandem mass spectromety (MS/MS). This study suggests that TMAPA-derivatized oligosaccharides used in ESI-MS and ESI-MS/MS would be effective for structural characterization of oligosaccharides that are available only in limited quantities.

Synthesis. -Air-stable, solid, and polyfunctional aryl and heteroarylzinc pivalates are efficiently prepared by either magnesium insertion or Hal/Mg exchange followed by transmetalation with Zn(OPiv) 2. Alternative routes are the directed magnesiation using TMP-MgCl·LiCl followed by transmetalation with Zn(OPiv) 2 or, for very sensitive substrates, direct zincation by using TMP-ZnOPiv. These zinc reagents not only show excellent stability towards air, but they also undergo a broad range of reactions with electrophiles. -(MANOLIKAKES, S. M.; ELLWART, M.; STATHAKIS, C. I.; KNOCHEL*, P.; Chem. -Eur.

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The influence of thin carbonate-containing apatite (CA) coating on trabecular bone response to cylindrical titanium fiber mesh (porosity of 85%, pore size of 200-300 microm, 2.8 mm diameter x 6 mm length) implants was investigated. Thin CA coatings were deposited by the so-called molecular precursor method. Molecular precursor solution was obtained by adding dibutylammonium diphosphate salt to Ca-EDTA/amine ethanol solution by adjusting Ca/P = 1.67. Sintered cylindrical titanium fiber mesh was immersed into molecular precursor solution and then tempered at 600 degrees C for 2 h. The immersion and tempering process was repeated three times. An adherent thin CA film could be deposited on the inside of titanium fiber mesh. After the immersion of a CA-coated titanium fiber mesh in simulated body fluid, apatite crystals precipitated on the titanium fiber mesh. Uncoated and CA-coated titanium fiber mesh was inserted into the trabecular bone of the left and right femoral condyles of rabbits. Histological and histomorphometrical evaluation revealed a significantly greater amount of bone formation inside the porous area of the CA-coated titanium fiber mesh after 12 weeks of implantation. The present results suggested that a thin CA-coated titanium mesh has better osteoconductivity and will be useful for a three-dimensional scaffold.

We examine the superconducting anisotropy γc = (mc/m ab ) 1/2 of a metallic high-Tc superconductor MgB2 by measuring the magnetic torque of a single crystal. The anisotropy γc does not depend sensitively on the applied magnetic field at 10 K. We obtain the anisotropy parameter γc = 4.31 ± 0.14. The torque curve shows the sharp hysteresis peak when the field is applied parallel to the boron layers. This comes from the intrinsic pinning and is experimental evidence for the occurrence of superconductivity in the boron layers. \pacs{74.25. Ha,

Most solid rockets are powered by ammonium perchlorate (AP) composite propellant including aluminum particles. As aluminized composite propellant burns, aluminum particles agglomerate as large as above 100 μm diameter on the burning surface, which in turn affects propellant combustion characteristics. The development of composite propellants has a long history. Many studies of aluminum particle combustion have been conducted. Optical observations indicate that aluminum particles form agglomerates on the burning surface of aluminized composite propellant. They ignite on leaving the burning surface. Because the temperature gradient in the reaction zone near a burning surface influences the burning rate of a composite propellant, details of aluminum particle agglomeration, agglomerate ignition, and their effects on the temperature gradient must be investigated. In our previous studies, we measured the aluminum particle agglomerate diameter by optical observation and collecting particles. We observed particles on the burning surface, the reaction zone, and the luminous flame zone of an ammonium perchlorate (AP)/ammonium nitrate (AN) composite propellant. We confirmed that agglomeration occurred in the reaction zone and that the agglomerate diameter decreased with increasing the burning rate. In this study, observing aluminum particles in the reaction zone near the burning surface, we investigated the relation between the agglomerates and the burning rate. A decreased burning rate and increased added amount of aluminum particles caused a larger agglomerate diameter. Defining the extent of the distributed aluminum particles before they agglomerate as an agglomerate range, we found that the agglomerate range was constant irrespective of the added amount of aluminum particles. Furthermore, the agglomerate diameter was ascertained from the density of the added amount of aluminum particles in the agglomerate range. We concluded from the heat balance around the burning surface that the product of the agglomerate range and the burning rate was nearly constant irrespective of the added amount of aluminum particles. Moreover, the reduced burning rate increased the agglomerate range.

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