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31.
Takegawa Y Deguchi K Ito S Yoshioka S Nakagawa H Nishimura S 《Rapid communications in mass spectrometry : RCM》2005,19(7):937-946
To investigate the possibility of structural assignment based on negative-ion MS2 spectral matching, three isomeric pairs of 2-aminopyridine (PA)-derivatized non-fucosylated, fucosylated, and sialylated oligosaccharides (complex type N-glycans) were analyzed using high-performance liquid chromatography/ion trap mass spectrometry (HPLC/ITMS) with a sonic-spray ionization (SSI) source. In the SSI negative-ion mode the deprotonated molecule [M-2H]2- becomes prominent. Negative-ion MS2 spectra derived from such ions contain many fragment types (B and Y, C and Z, A, and D) and therefore are more informative than the positive-ion MS2 spectra derived from [M+H+Na]2+ ions, which usually consist mainly of B and Y fragment ions. In particular the internal ions (D- and E-type ions) provided useful information about the alpha1-6 branching patterns and the bisecting GlcNAc residue. Spectral matching based on the correlation coefficients between negative-ion MS2 spectra was performed in a manner similar to the positive-ion MS2 spectral matching previously reported. It was demonstrated that negative-ion MS2 spectral matching is as useful and applicable to the structural assignment of relatively large non-fucosylated, fucosylated, and sialylated PA-oligosaccharide isomers as its positive-ion counterpart. 相似文献
32.
Yuichi Michiue 《Journal of solid state chemistry》2006,179(8):2578-2583
Phase relations of rutile, freudenbergite, and hollandite structures were examined in the pseudobinary system NaCrO2-TiO2 (i.e., NaxCrxTi8−xO16) at 1350 °C. The hollandite structure was obtained in the composition range 1.7?x?2.0. The symmetry of the samples at room temperature was tetragonal for x=1.7 and 1.75, and monoclinic for x=1.8 and above. Single crystals of monoclinic hollandite Na2Cr2Ti6O16 were grown and the structure refinement has been carried out using an X-ray diffraction technique. The space group was I2/m and cell parameters were a=10.2385(11), b=2.9559(9), c=9.9097(11)Å, and β=90.545(9)° with Z=1. The Na ion distribution in the tunnel was markedly deformed from that in the tetragonal form. It was suggested that Cr/Ti ratios were different between the two framework metal sites. 相似文献
33.
Keishi Nishio Yuichi Watanabe Toshio Tsuchiya 《Journal of Sol-Gel Science and Technology》2003,26(1-3):245-250
In this study, we prepared Sr
x
Ba1 – x
Nb2O6 (x = 0.3, 0.5 and 0.7) thin film on 0.75 wt% La doped SrTiO3 (100) and (110) single crystal substrates. A homogeneous coating solution was prepared with Sr and Ba acetates and Nb(OEt)5 as raw materials, and acetic acid and diethlene glycol monomethyl ether as solvents. The substrates were coated with the solution by spin coating method. As-coated thin films were heated from 973 to 1273 K in air. The grains of the thin film on La doped SrTiO3 (100) were pillar shaped and arranged in right angle to each other. On the other hand, the grains of these thin films on La doped SrTiO3 were pillar shape and arranged in one direction. The crystallographic relationship of the thin film between Sr
x
Ba1 – x
Nb2O6 and substrate that the 130 and 310 direction of the thin film on the substrate were oriented with c-axis in parallel to the substrate surface. On the other hand, (hk0) phase diffractions of Sr
x
Ba1 – x
Nb2O6 thin film on the substrate (110) were investigated in the XRD theta-2theta measurement. It is expected that the Sr
x
Ba1 – x
Nb2O6 (x = 0.3, 0.5 and 0.7) were highly oriented or epitaxial growing on La doped SrTiO3 (110) single crystal substrate. 相似文献
34.
Alkylation of cyclohexenyl monoacetate 1 with R2Cu(CN)(MgCl)2 or RMgBr/CuCN (cat.) in Et2O produced trans 1,2-isomers 4, while arylation and alkenylation of 1 was accomplished with lithium borates 5 and a nickel cat. to afford trans 1,4-isomers 3 selectively. Furthermore, several transformations of the products were carried out to demonstrate synthetic advantages of the present reactions. 相似文献
35.
Shimazawa R Sano H Tanatani A Miyachi H Hashimoto Y 《Chemical & pharmaceutical bulletin》2004,52(4):498-499
Thalidomide has been found to exhibit weak nitric oxide synthase (NOS)-inhibitory activity. Structural development studies of thalidomide showed that some N-2,6-dimethylphenylhomophthalimide analogs possess NOS-inhibiting activity. 相似文献
36.
Du YZ Hiratsuka Y Taira S Eguchi M Uyeda TQ Yumoto N Kodaka M 《Chemical communications (Cambridge, England)》2005,(16):2080-2082
A new nano-biomachine has been created from microtubules (MTs) and hetero-bifunctional polymer particles bearing pyruvate kinase, which is propelled on glass surfaces coated with kinesin by use of self-supplying ATP. 相似文献
37.
Fukushima S Miyata K Nishiyama N Kanayama N Yamasaki Y Kataoka K 《Journal of the American Chemical Society》2005,127(9):2810-2811
An A-B-C type triblock copolymer, tandemly aligning two types of polycations with different pKa values in a single polymer strand, was developed for the construction of novel polyplex micelles, satisfying a high DNA condensing ability as well as a proton buffering activity directed to elevating gene transfection. The micelle might feature the distinctive three-layered structure, where an inner polyplex layer of condensed pDNA with poly(l-lysine) (pKa approximately 9.4) as the C segment is successively wrapped with an intermediate layer of poly[(3-morpholinopropyl)aspartamide] (B segment) with a comparatively low pKa of approximately 6.2, to provide a buffering effect, and an outer PEG layer (A segment) as a biocompatible palisade. 相似文献
38.
Adachi K Sugiyama Y Yoneda K Yamada K Nozaki K Fuyuhiro A Kawata S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(22):6616-6628
Novel triply hydrogen bonded suprastructures based on [M(tdpd)2(L)2]2- (H2tdpd=1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile, L=solvent) and melamine-analogous cations have been synthesized and characterized. The use of anions containing two AAA sets from [M(tdpd)2(L)2]2- together with cations containing one DDD set (A=hydrogen-bond acceptor, D=hydrogen-bond donor) leads to the formation of complementary triply hydrogen bonded modules in the solid state. In all cases, the building module is further extended via additional hydrogen-bonding interactions to produce a tape, and tapes are assembled into sheets. These results show that a hydrogen-bonded module consisting of different kinds of building blocks, one of which is a metal complex that includes hydrogen-bond acceptor sites and the other is a hydrogen-bond donor molecule, will be attractive for constructing metal-containing supramolecular systems by the self-assembly technique. 相似文献
39.
When tert-alcohols were treated with (COOH)2 and NaSCN in the presence of iodine, tertiary alkyl isothiocyanates were obtained in good yield, whereas the corresponding thiocyanates were obtained in low yield in the absence of iodine. 相似文献
40.
Ptilomycalin A and crambescidins, novel marine guanidine alkaloids, have a unique pentacyclic guanidine structure, and exhibit a considerable array of biological activities. The first method developed for the synthesis of the pentacyclic guanidine core structure involved successive 1,3-dipolar cycloaddition reactions and resulted in the first total synthesis of crambescidin 359. The synthesis of other pentacyclic guanidine derivatives has been based on this methodology and applied as tools for studying biological activities, and as chemical reaction catalysts. 相似文献