A series of novel carbohydrate chains all possessing a hitherto unknown trisaccharide unit, Ga1NAc beta 1 leads to 4-(NeuGc2 leads to 3)Ga1NAc beta 1 leads to, have been isolated from trout egg polysialoglycoproteins, a new class of glycoproteins, on alkali-borohydride treatment. On the basis of chemical (methylation, Smith degradation, and hydrazinolysis-nitrous deamination) and direct-probe mass spectrometric methods. deamination) and direct-probe mass spectrometric methods, the structures of a series of the first major type of oligosaccharide alditols having a sialidase-resistant N-glycolyneuraminic acid residue in each molecule were determined. The structures thus determined are novel and all possess a unique carbohydrate sequence (sialidase-resistant unsubstituted sialyl group italicized): Ga1NAc beta 1 leads to 4(NeuGc2 leads to 3)Ga1NAc beta 1 leads to 3Gal beta 1 leads to-4Gal beta 1 leads to 3[(leads to 8NeuGc alpha 2)n leads to 6]Ga1NAcol (n = 0 through 3).
The occurrence of the α2→8-linked oligomeric form of N-glycolylneuraminic acid (oligo-Neu5Gc) residues in mammalian glycoproteins was unequivocally demonstrated using a newly developed anti-oligo/poly-Neu5Gc monoclonal antibody as well as by chemical and biochemical methods. First, the antibody, designated mAb.2–4B, which specifically recognized oligo/poly-Neu5Gc with a degree of polymerization of >2, was developed by establishing a hybridoma cell line from P3U1 myeloma cells fused with splenocytes from an MRL autoimmune mouse immunized with dipalmitoylphosphatidylethanolamine-conjugated oligo/poly-Neu5Gc. Second, oligo-Neu5Gc was shown to occur in glycoproteins derived from pig spleen by Western blot analysis using mAb.2–4B, which was also confirmed by fluorometric high performance liquid chromatographic analysis of the product of periodate oxidation/reduction/acid hydrolysis of the purified glycopeptide fractions and by TLC and 600-MHz 1H NMR spectroscopic analysis of their mild acid hydrolysates. Finally, the ubiquitous occurrence of oligo-Neu5Gc chains as glycoproteinaceous components in Wistar rat tissue was immunochemically indicated. This is the first example demonstrating the diversity in oligo/poly-Sia structure in mammalian glycoproteins, where only poly-N-acetylneuraminic acid is known to occur. Such diversity in oligo/poly-Sia structure also implicates a diverged array of biological functions of this glycan unit in glycoproteins.
An AC8A aluminum alloy matrix composite reinforced with highly crystallized potassium titanate whisker having a crystallite size of 76 nm was fabricated by squeeze casting. Heat hardening behavior and mechanical properties were examined on the obtained composites whose Mg contents in the matrix were from 0.7 to 1.9 mass%.The Mg content and hardness of the composite were uniform at any locations. The composite whose Mg content in the matrix were 1.7 mass% solutionized at 803 K showed the highest strength value at room temperature and 573 K, respectively. And the Young’s modulus was as high as 138 GPa. The decrease in strength during exposure at up to 573 K was not observed. In particular, the properties of the obtained composite were found to be useful for the elevated temperature materials.
The chemical shifts of all the ring protons of the three Man residues in a pentaantennary glycan chain have been unambiguously assigned by two-dimensional proton nuclear magnetic resonance (1H-NMR) spectroscopic methods. The study, using chemical shift and J values on the conformation of the trimannosyl unit, revealed that the rotamer about the C5-C6 bond of the α16 linkage in the sequence of Manα16Manβ1 is predominantly confined to a gauche-gauche rotamer (ω= 180°, ω= O6-C6-C5-H5) and not to a gauche-trans rotamer (ω=–60°). We do not know of any previous demonstration that the dihedral angle ω (O6-C6-C5-H5) in Manα16Manβ1 is preferentially 180° in complex-type N-linked glycans having no bisecting GlcNAc residue.
The breakdown test under DC-Impulse and DC-AC superposed voltage, of an oil impregnated capacitor dielectric is carried out to study the influence of a DC superposed voltage on the breakdown characteristics.The insulation configuration of the dielectric includes three types-oil-impregnated paper, paperfilm (polypropylene), and all-film, each of which uses alkyl-naphthalene as the insulating oil in making a sample capacitor. From the DC-Impulse superposition test, it is found that the breakdown of each capacitor is determined by a certain algebraic sum of the DC and Impulse electric fields regardless of the polarity (forward or reverse polarity) and ratio of DC to Impulse.From repetitive service-life test, it is found that the service life is inversely proportional to approx. the 13th power of the pulse electric field in the reverse-polarity pulse area of a paper capacitor and to approx. 55th power of it in the short-term area and short-time and sustained use areas of the foward-polarity pulse. For all-film and paper-film samples, it is found that the service life is inversely proportional to approx. the 55th power of the puls electric field in the sustained use area (several thousands of times) or both the foward and reverse polarities.From the result of the DC-AC superposed voltage test, several facts can be obtained namely that the influence of the DC superposed voltage on the shortterm breakdown voltage is large for any dielectric configuration but, is small in the sustained use area.
The chapter contains sections titled: Introduction N-Glycosylatiod/De-N-glycosylation Occurrence of PNGases: The Discovery of Animal PNGases PNGases in Fish PNGase in Mouse-Derived Cultured Cells: L-929 PNGase Neutral, Soluble PNGases are Widely Distributed in Mouse Organs Possible Biological Function of Neutral PNGase in “Non-Lysosomal” Degradation Plant PNGases: Possible Regulator Molecules in Cellular Processes Concluding Remarks
The hole-initiated impact-ionization rate in α-quartz was investigated using both an energy band structure and the corresponding pseudowave functions, which are derived from a self-consistent nonlocal pseudopotential method. The ionization probability is calculated formally from Fermi’s golden rule in a straightforward way. The matrix elements for the ionization transition were evaluated from the band structure and the corresponding pseudowave functions. The matrix elements include both direct and the exchange terms with umklapp terms associated with the periodic part of the Bloch function. The hole-initiated impact-ionization rate is discussed with emphasis on both the anisotropy (wave-vector dependence of the primary hole) associated with the band structure and the contribution of the umklapp process to the impact-ionization rate. In contrast to the Keldysh formula, which has a power exponent of 2, the computed impact-ionization rates are fitted to an analytical formula that has a power exponent of 6.7, which originates from the complexity of the α-quartz band structure. We have found that primary holes that exist in the eighth and ninth valence bands labeled from the lowest valence band in ascending order especially contribute to the subthreshold region of ionization. In addition, we show the average energies of the secondary holes and electrons generated at the moment of transition as a function of the initial hole energy.
