NMR structure elucidation of cyclic sialyl 6-sulfo Lewis x, a biologically dormant form of L-selectin ligand

The structure of cyclic sialyl 6-sulfo Lewis x, a new biologically dormant form of L-selectin ligand, was determined unambiguously by the accurate NMR analysis to have the lactamized ^{[5.], (a), (b), [2.], (a) and (b)}B conformation of its sialic acid. For the NMR structure elucidation were used various informations, such as chemical shifts values, appearance of amide proton, and NOE.     

Study on the constituents of Desmodium styracifolium

Two triterpenoid saponins (1 and 2) were isolated from Desmodii Herba [the dried whole plants of Desmodium styracifolium (Osbeck) Merr. (Leguminosae)] and their chemical structures were characterized as soyasaponin I and a new saponin, 3-O-[alpha-L-rhamnopyranosyl-(1----2)-beta-D-galactopyranosyl- (1----2)-beta-D-glucuronopyranosyl]soyasapogenol E, respectively, by chemical and spectroscopic means.     

Occurrence of the cis-peptide in gaseous N-methylformamide as revealed by rotational structure in its infrared spectrum

In the 0.12 cm^?1 resolution infrared absorption spectrum of gaseous N-methylformamide, a progression of peaks with a spacing of about 2.6 cm^?1 has been found in the 610-540 cm^?1 region. This is assignable to a conformer with the CO and NH bonds cis to each other.     

Phase relationships and thermodynamic interactions in linear polyethylene–diluent systems

Phase equilibria between linear polyethylene and a number of organic diluents of varying type have been investigated. The diluents include aliphatic alcohols, alkyl phenols, aryl phenols, diphenyl derivatives, alkyl aryl ethers, esters, and ketones. It is found that n-octyl alcohol, n-decyl alcohol, n-lauryl alcohol, p-tert-amyl alcohol, p-octyl phenol, p-nonyl, phenol, diphenyl, diphenylmethane, diphenyl ether, benzyl phenyl ether, and anisole are Θ-solvents for linear polyethylene at temperatures between 120 and 200°C. Thermodynamic interactions are discussed in relation to the type of diluent.     

Dynamic kinetic resolution catalyzed by Ir axially chiral phosphine catalyst: asymmetric synthesis of anti aromatic beta-hydroxy-alpha-amino acid esters

The anti selective hydrogenation of alpha-amino-beta-keto esters via dynamic kinetic resolution was achieved for the first time by using the iridium-MeOBIPHEP catalyst in asymmetric synthesis of anti aromatic beta-hydroxy-alpha-amino acid esters with excellent diastereo- and enantioslectivities. Acetic acid as a solvent and sodium acetate as an additive affected dramatically the yield and the enantioselectivity, respectively. The product anti aromatic beta-hydroxy-alpha-amino acid esters are useful for synthesis of pharmaceuticals and natural products.     

Preparation of uniform spherical aluminum hydrous oxide particles from acetylacetonato-aluminum solutions

Uniform spherical particles of amorphous aluminum hydrous oxide (0.45 m in diameter with a relative standard deviation of 0.09) were produced under a limited set of conditions in an aluminum sulfate/acetylacetone system at 100°C aged for 24 h. Grain-like crystalline -AlOOH particles (2.6 m in length with a relative standard deviation of 0.10) were also prepared in the absence of sulfate ions at 100°C for 42 h. Their morphology and size were sensitive to the total aluminum concentration, even though the initial pH was kept the same. The temperature dependence of the absorption spectra of acetylacetonato-aluminum complexes indicated their exothermic formation. These complexes release free aluminum ions at elevated temperatures, which subsequently hydrolyzed. The resulting polymerized hydroxo-aluminum species complexes with the sulfate ion act as precursors to particle formation.     

Antibody-scanning and epitope-tagging methods; molecular mapping of proteins using antibodies

Because synthetic short peptides bearing critical binding residues, can chemically mimic the folded antigenic determinants on proteins, short synthetic peptides can generate antibodies that react with cognate sequences in intact folded proteins. According to this mimotope theory, we produced site-specific antibodies by immunization with short peptides which overlapped each other and covered the entire protein, and used them for domain mapping of influenza virus RNA polymerase (antibody-scanning method). We also used a tagged-epitope and its monoclonal antibodies for topology mapping of clathrin light chains in clathrin triskelions by electron microscopy. Both methods using specific epitopes in combination with their antibodies enable us to determine the domains of interesting proteins systematically without the need to generate monoclonal antibodies or mutant proteins.     

Strong binding between acidic guests and fluorescein modified -γ-Cyclodextrin via hydrogen bonding

-Cyclodextrin with appended fluorescein (1) has been prepared as a sensor and a charge-changeable receptor for detecting organic compounds including terpenoids, carboxylic acids and bile acids. Compound1 has cationic, neutral and anionic forms depending on the pH of the solutions. The anionic form of1 at about neutral pH exhibits the highest sensing ability for carboxylic acids and bile acids, while at alkaline pH it detects hardly any of the guests examined. The high sensitivity and selectivity of the anionic form of1 at around neutral pH for acidic guests seems to be caused by the hydrogen bond between the phenoxide anion moiety of fluorescein and acidic guests. The neutral form of1 exhibits little sensing ability for all the guests, but the cationic form shows comparatively higher sensing ability for the guests examined.     

Spectroscopic Characterization and Catalytic Activity of Some Cu(II)-thiosemicarbazide Complexes

The complexes of thiosemicarbazide (HTS) have been prepared and characterized by spectral, thermal and magnetic studies. The deprotonation constant of HTS and the formation constants of its complexes were evaluated pH-metrically. The Cu(II) acetate-HTS system gave high stability. The catalytic activity of Co(II), Ni(II) and Cu(II) complexes was tested to decompose H₂O₂. The Co(II) complex has no activity whereas the Cu(II) complex was found to be more active than Ni(II). The different Cu(II) complexes were tested; [Cu₂(TS)(OH)₂(OAc)] was highly active. All parameters affecting the reaction rate (concentration of H₂O₂, weight of catalyst, temperature and pH) were studied and the optimum conditions were evaluated. Attempts to increase the activity of [Cu₂(TS)(HO)₂(OAc)] by mixing with superconducting cuprate sample, Nd_0.1Y_0.9Ba₂Cu₃O_7-δ, will be the subject of further studies.     

Effect of molding parameters on the properties of PP/PP sandwich injection moldings

The basic characteristics of a sandwich injection molded product depend on the properties of the respective resins that comprise the skin and core layers, and the skin/core resin volume ratio. The characteristics of the core layer resin and the skin/core ratio in particular may vary depending on the injection molding conditions. This report considers the influences that the molding conditions such as injection speed, cylinder temperature, and mold temperature confer on the mechanical properties of the sandwich moldings. The study employed, skin/core resin combinations involving similar and dissimilar materials i.e. homopolymer PP/homopolymer PP and homopolymer PP/copolymer PP, respectively. It was demonstrated that core cylinder temperature and mold temperature could be used to adjust the mechanical properties of sandwich injection moldings. In the case of single material sandwich moldings, injection speed seemed to play no significant role, even though it was clearly demonstrated that core volume increases with injection speed. However, core injection speed plays a significant role in the dual material system by lowering or increasing the mechanical strength of moldings as the case may be. Thus, the dormant or active role of injection speed depending on the material system has been highlighted.