The Full Structure of the Carbohydrate Chain of the Lipopolysaccharide of Providencia alcalifaciens O19

An oligosaccharide isolated from the lipopolysaccharide of Providencia alcalifaciens O19 was found to consist of a single O‐antigen repeating unit linked to the core. The full oligosaccharide structure was elucidated by 2D ¹H, ¹³C, and ³¹P NMR spectroscopy. It was shown that the inner core region has the same structure as in other Providencia strains studied, whereas the outer core is structurally diverse between Providencia strains. A pyruvic acid acetal was found in the isolated oligosaccharide and in the long‐chain O‐antigen, whose structure has been established earlier. The biological O‐unit structure was elucidated in the short‐chain lipopolysaccharide.     

Elucidation of the Lipopolysaccharide Core Structures of Bacteria of the Genus Providencia

Enterobacteria of the genus Providencia are opportunistic pathogens causing diarrhea in travelers and children. Lipopolysaccharide (LPS) is the major surface antigen of Providencia and the major target of the immune response. O‐polysaccharide structures have been elucidated in several Providencia O‐serogroups, but little is known about the LPS core structure. We isolated core oligosaccharides from the R‐type LPS of a number of Providencia O‐serogroups and studied them by high‐resolution mass spectrometry, including capillary skimmer dissociation technique; three selected oligosaccharides were analyzed also by NMR spectroscopy. The conserved inner core and variable outer core regions were distinguished and the full core oligosaccharide structures established in Providencia O8, O35, and O49. Providencia LPSs were found to share some structural features with Proteus LPSs.     

A Novel Divalent Ytterbium Complex Supported by a Bridged Diamide Ligand： Synthesis and Structure of [{Me2Si（NPh ）2Yb（THF）2}（μ3-CI）（μ4-CI）{Li（TH F） }2]2·2THF

The reaction of anhydrous YbCl3 with 1 equiv, of Li2Me2Si（NPh）2 in THF, after workup, yielded a ytterbium（Ⅲ） chloride [{Me2Si（NPh）2Yb}（μ2-CI）（TMEDA）]2·3PhMe （1） （TMEDA=tetramethylethanediamine）. The same reaction followed by treatment with Na-K alloy afforded a new ytterbium（H） complex supported by a bridged diamide with four coordinated LiC1 molecules, [{Me2Si（NPh）2Yb（THF）2}（μ3-CI）（μ4-CI）{Li（THF）}2]2·2THF （2） in high yield. Both complexes were structurally characterized by X-ray analysis to be dimers. Complex 1 was a chlorine-bridged dimer with ytterbium in a distorted octahedral geometry. In complex 2 two [Me2Si（NPh）2Yb（THF）2]- （μ3-CI）[Li（THF）]2 moieties were connected with each other by two μ4-CI bridges to form a ＂chair-form＂ framework.     

New synthesis of 4-O (β-D-galactopyranosyl)-2-acetamido-2-desoxy-d-glucose (N-acetyllactosamine)

Conclusions The addition of nitrosyl chloride to hexaacetyllactal, followed by reduction of the formed lactose chloronitroso derivative, gave N-acetyllactosamine octaacetate, the de-O-acetylation of which leads to the crystalline N-acetyllactosamine.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2365–2366, October, 1973.     

星形聚合物结构的统计分析

本文用概率统计方法对偶联型星形聚合物的结构进行了系统理论分析,得到了偶联产物的分子量分布、平均分子量、平均支化度等重要结构参数与偶联剂官能度、偶联度以及起始活性聚合物分布的定量关系式。同时,文中还讨论了多官能度引发聚合反应的情况,结果表明,这类反应产物的分子量分布,可作为偶联星形聚合物分子量分布一般关系式的特例处理。     

Oxoalkoxides—True precursors of complex oxides

X-ray structural analysis of crystalline alkoxides in many cases reveals that along with OR-groups their molecules also contain oxo-ligands. The following possible reactions leading to formation of oxoalkoxides have been discussed: hydrolysis, pyrolysis (frequently uncontrollable), ether elimination, oxidation of OR-groups (which exist in solutions of alkali, alkaline-earth and rare earth elements), or alkoxides of the lower oxidation states (which are formed by reduction of M(OR) _n on cathode during electrolysis or by hydrogen in statu nascendi). Oligomeric oxoalkoxides differ from the polymeric alkoxides M(OR) _n in considerably higher solubility and reactivity. The most important role of oxoalkoxides in the processes of formation of oxides has been demonstrated using as an example preparation of BaTiO₃ from alkoxides.     

Effect of substituent in para-substituted anilines on the isomerization rate of 5-vinylbicyclo[2,2,1]hept-2-ene catalyzed by anilinepentacarbonyliron complexes

The isomerization kinetics of 5-vinylbicyclo [2,2,1]-hept-1ene to 5-enthylidenbicyclo [2,2,1] hept-2-ene in the presence of iron pentacarbonyl and parasubstituted anilines has been investigated. The kinetic data correlate with -constants of the substitutes according to Jaffe.

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5- [2,2,1]-2- 5- [2,2,1] -2- - . - .

     

Full structure of the carbohydrate chain of the lipopolysaccharide of Providencia rustigianii O34

A lipopolysaccharide isolated from an opportunistic pathogen of the Enterobacteriaceae family Providencia rustigianii O34 was found to be a mixture of R-, SR-, and S-forms consisting of a lipid moiety (lipid A) that bears a core oligosaccharide, a core with one O-polysaccharide repeating unit attached, and a long-chain O-polysaccharide, respectively. The corresponding carbohydrate moieties were released from the lipopolysaccharide by mild acid hydrolysis and studied by sugar and methylation analyses along with one- and two-dimensional NMR spectroscopy and high-resolution electrospray ionization mass spectrometry. As a result, the structures of the core and the O-polysaccharide were established, including the structure of the biological repeating unit (an oligosaccharide that is preassembled and polymerized in biosynthesis of the O-polysaccharide), as well as the mode of the linkage between the O-polysaccharide and the core. Combining the structure of the carbohydrate moiety thus determined and the known structure of lipid A enabled determination of the full lipopolysaccharide structure of P. rustigianii O34.     

Analyzing dynamic interaction of impulse-loaded strips

The paper considers the dynamic process of contact interaction of infinite impulse-loaded strips arranged with a gap. The behavior of the strips is described by linear elastic dynamics equations. The contact problem is solved by the collocation method. The process of impact of two and three strips is analyzed. The calculation results are compared with data obtained by using the finite-element method.     

回归正交试验设计在水飞蓟素提取工艺中的应用

本文针对水飞蓟素提取工艺利用二次回归正交设计 ,进行了五个变量的正交回归设计 ,获得了最佳的试验工艺参数值以及相应的数学模型