2 research outputs found
Acetylation in Ionic Liquids Dramatically Increases Yield in the Glycosyl Composition and Linkage Analysis of Insoluble and Acidic Polysaccharides
Glycosyl composition and linkage analyses are important
first steps
toward understanding the structural diversity and biological importance
of polysaccharides. Failure to fully solubilize samples prior to analysis
results in the generation of incomplete and poor-quality composition
and linkage data by gas chromatography–mass spectrometry (GC-MS).
Acidic polysaccharides also do not give accurate linkage results,
because they are poorly soluble in DMSO and tend to undergo β-elimination
during permethylation. Ionic liquids can solubilize polysaccharides,
improving their derivatization and extraction for analysis. We show
that water-insoluble polysaccharides become much more amenable to
chemical analysis by first acetylating them in an ionic liquid. Once
acetylated, these polysaccharides, having been deprived of their intermolecular
hydrogen bonds, are hydrolyzed more readily for glycosyl composition
analysis or methylated more efficiently for glycosyl linkage analysis.
Acetylation in an ionic liquid greatly improves composition analysis
of insoluble polysaccharides when compared to analysis without acetylation,
enabling complete composition determination of normally recalcitrant
polysaccharides. We also present a protocol for uronic acid linkage
analysis that incorporates this preacetylation step. This protocol
produces partially methylated alditol acetate derivatives in high
yield with minimal β-elimination and gives sensitive linkage
results for acidic polysaccharides that more accurately reflect the
structures being analyzed. We use important plant polysaccharides
to show that the preacetylation step leads to superior results compared
to traditional methodologies
BVRI photometric observations and light-curve analysis of GEO objects
BVRI photometric observations of Geosynchronous Earth Orbit (GEO) objects were conducted with the 1.5 m Cassini Telescope
located in Loiano, Italy. The observatory is operated by the INAF (National Institute for Astrophysics) Astronomical Observatory
of Bologna, Italy. The Ritchey–Chre´tien optical system is equipped with the BFOSC (Bologna Faint Object Spectrograph and Camera),
a multipurpose instrument for imaging and spectroscopy, with an EEV CCD (13401300 pixel).
This paper deals with the results of the photometric observations of several targets from the SSN (Space Surveillance Network) catalog that were acquired in May and December 2013