Comparative structural study of the lipopolysaccharides of Y. enterocolitica serovars 0:7.8 and 0:19.8

The lipopolysaccharides ofYersinia enterocolitica, serovars 0:7.8 (strain 106) and 0:19.8 (strain 842), isolated from the microbial mass by phenol-water extraction, contained residues of L-fucose, 6-deoxy-D-gulose, D-mannose, D-galactose, D-glucose, D- and L-glycero-D-mannoheptoses, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, and 2-keto-3-deoxyoctonic acid (KDO). The polysaccharides obtained by mild acid hydrolysis of the lipopolysaccharides followed by gel filtration on Sephadex G-50 were a mixture of the O-specific polysaccharide and the core, which could not be separated even by repeated rechromatography because of the comparability of their molecular masses. On the basis of the results of monosaccharide analysis, methylation, Smith degradation, and partial hydrolysis, a structure has been suggested for the repeating unit of the O-specific polysaccharides of the lipopolysaccharides ofY. enterocolitica of the serovars studied. Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, USSR Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 763–770, November–December, 1989.     

Chemical and immunochemical characterization of the lipopolysaccharides of Yersinia kristensenii serovars 0:12,25; 0:12,26; and 0:25,35

A comparative and immunochemical characterization of the lipopolysaccharides of three serovars ofY. kristensenii has been performed and the ratios of the monosaccharides have been established. The results of the immunochemical investigations confirmed the serotyping of the microorganisms.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 335–338, May–June, 1988.     

Structural investigation of the lipopolysaccharide ofYersinia enterocolitica serovar 0:8

The lipopolysaccharide ofYersinia enterocolitica serovar 0:8 (strain 161) isolated from the microbial mass by aqueous-phenol extraction contains residues of L-fucose-6-deoxy-D-gulose, D-mannose, D-galactose, D-glucose, D- and L-glycero-D-mannoheptoses, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, and 2-keto-3-deoxyoctonic acid (KDO). The polysaccharide was obtained by mild acid hydrolysis of the lipopolysaccharide followed by gel filtration on Sephadex G-50. On the basis of the results of monosaccharide analysis, methylation, Smith degradation, and partial hydrolysis the following structure is suggested for the repeating unit of the O-specific polysaccharide of the LPS ofYersinia enterocolitica, serovar 0:8:     

Comparative study of imidazole hydration: Ab initio and electrostatic calculations vs. Cambridge structural database analysis

We studied geometries and energies of complexes between water and neutral or protonated imidazole by ab initio molecular orbital calculations using the 4-31G basis set with and without the counterpoise correction. Positions of hydration sites and relative binding energies could be also estimated by using the electrostatic field map of imidazole as calculated by our bond increment method. The reliability of the calculations is confirmed by comparing the geometries of the imidazole-water complex to the experimental ones from the Cambridge Structural Database. These were obtained by X-ray diffraction studies on crystals with water bound to a molecule containing the imidazole fragment.     

Electronic properties and 13C NMR structural study of Y3N@C88

In this paper, we report the synthesis, purification, (13)C NMR, and other characterization studies of Y(3)N@C(88). The (13)C NMR, UV-vis, and chromatographic data suggest an Y(3)N@C(88) having an IPR-allowed cage with D(2)(35)-C(88) symmetry. In earlier density functional theory (DFT) computational and X-ray crystallographic studies, it was reported that lanthanide (A(3)N)(6+) clusters are stabilized in D(2)(35)-C(88) symmetry cages and have reduced HOMO-LUMO gaps relative to other trimetallic nitride endohedral metallofullerene cage systems, for example, A(3)N@C(80). In this paper, we report that the nonlanthanide (Y(3)N)(6+) cluster in the D(2)(35)-C(88) cage exhibits a HOMO-LUMO gap consistent with other lanthanide A(3)N@C(88) molecules based on electrochemical measurements and DFT computational studies. These results suggest that the reduced HOMO-LUMO gap of A(3)N@C(88) systems is a property dominated by the D(2)(35)-C(88) carbon cage and not f-orbital lanthanide electronic metal cluster (A(3)N)(6+) orbital participation.     

Comparative study of the textural and structural properties of the aerogel and xerogel sulphated zirconia

Aerogel and xerogel sulphated zirconia with defined atomic ratio S/Zr = 0.5 and molar hydrolysis ratio h = nH₂O/nZrO₂ = 3 show different textural and structural properties after calcination at high temperatures. The aerogel obtained just after solvent evacuation develops only the tetragonal phase, whereas the xerogel dried in an oven is amorphous. Heating to a temperature above 833 K, leads to transition of the tetragonal phase to the monoclinic one for the two solids, due to sulphur loss but the tetragonal phase remains stable for the aerogel . Raman, Infrared and XPS spectroscopies show that the loss of the sulphur at high temperatures seems to be easier for the xerogel than for the aerogel.     

Comparative first-principles study of structural and optical properties of alkali metal azides

A comparative first-principles study of the structural and optical properties of the alkali metal azides has been performed with density functional theory within the generalized gradient approximation. The crystal structures of the alkali azides compare well with experimental data. Their ionic character is manifested by the closeness of their internitrogen distances to the calculated N-N bond length for the free azide ion. An analysis of electronic structure, charge transfer, and bond order shows that the alkali azides are all wide-gap insulators and ionic compounds. The energy band and density of states for lithium azide and alpha-sodium azide are very similar, while these for potassium azide, alpha-rubidium azide, and alpha-cesium azide are alike, but some modifications are observed with the increment of alkali metals' electropositivity. These changes are closely related to the differences of the crystal structures. The general shapes of the real and imaginary parts of the dielectric function, adsorption coefficient, and electron energy-loss spectra are quite similar. The peaks originate from the electron transitions from the alkali metal s and p states to the conduction band. Our calculated optical properties for the alkali azides are found to be in good agreement with available experimental data. The absorption spectra of the alkali azides show a number of absorption peaks, which are believed to be associated with different exciton states, in the fundamental absorption region. In general, the electron energy-loss spectra have two plasma frequencies.     

Comparative study on the thermal behavior of structural concretes of sodium-cooled fast reactor

Journal of Thermal Analysis and Calorimetry - Thermal behaviors of two different siliceous concretes used in a sodium-cooled fast reactor were comparatively investigated in a temperature range from...     

Theoretical study of tetrahydrofuran: Comparative investigation of spectroscopic and structural properties between gas and liquid phases

Rovibrational spectroscopic constant of tetrahydrofuran (THF) dimer have been calculated starting from three potential energy curves, each one obtained in a different way: (i) by ab initio calculations at MP2/aug‐cc‐pVDZ level; (ii) using Lennard‐Jones liquid parameters available in the literature, and (iii) from the pair obtained through Monte Carlo Simulation of liquid THF. The comparison among these results allowed the characterization of many solvent effect contributions. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

BaCe_(0.8)Y_(0.2)O_(3-α)固体电解质的离子导电性及其燃料电池性能

用高温固相反应合成了BaCe0.8Y0.2O3-α固体电解质用氢浓差电池和氧浓差电池方法研究了它的离子导电特性。以该氧化物为固体电解质多孔性Pt为电极材料组成氢空气燃料电池测定了该燃料电池的电流电压特性。研究发现BaCe0.8Y0.2O3-α在氢气中几乎是一个纯的质子导体在氧气中是一个氧离子和电子空穴的混合导体其燃料电池的开路电压OCV接近于理论值最大输出电流密度约为820mA·cm-21000℃最大输出功率密度约为200mW·cm-21000℃放电性能稳定具有良好的电池性能。     

Lipids and lipopolysaccharides of the genusFlavobacterium

The fatty acid compositions of the free lipids of three strains and the monosaccharide compositions of the lipopolysaccharides of four strains of new species of microorganisms of the genusFlavobacterium have been studied. The acidic nature of the polysaccharides of the LPSs of the microorganisms studied has been shown.     

Comparative semiempirical and ab initio study of the structural and chemical properties of uric acid and its anions

Semiempirical, density functional theory (DFT), and ab initio calculations have been performed to assess the relative stabilities of 15 possible tautomer forms of neutral uric acid, and of the different urate mono‐ and dianion forms. These methods have also been used to compute ionization potentials (IPs) for uric acid and its derived anions. Overall, we have found that semiempirical calculations, in particular PM3, perform well as compared with B3LYP or MP2 computations toward these different structural and chemical properties of uric acid: the triketo form of uric acid is the most stable tautomer form of neutral uric acid. Three other tautomer forms are relatively close in energy, within the range 2–6 kcal/mol above the triketo form, with a mean energy deviation of only 1.3 kcal/mol between PM3 and DFT or ab initio results; the monoanion form of uric acid obtained by abstracting one proton in position 3 (denoted UAN) is the most stable form among all four possible urate monoanions both in gas phase and in solution; the dianion form of uric acid obtained by abstracting two protons, respectively, in positions 3 and 9 of uric acid (denoted UANN) is the most stable urate dianion form both in gas phase and in solution. However, these two most stable species do not have the lowest IPs in solution: among monoanions and dianions, respectively, the species with the lowest IPs are UAN and UANN. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Comparative study on the structural, optical, and electrochemical properties of bithiophene-fused benzo[c]phospholes

Three types of bithiophene-fused benzo[c]phospholes were successfully prepared by Ti(II)-mediated cyclization of the corresponding dialkynylated bithiophene derivatives as a key step. Each sigma(3)-phosphorus center of the benzo[c]phosphole subunits was readily transformed into sigma(4)-phosphorus center by Au coordination or oxygenation. In addition, the bithiophene subunit was functionalized at the alpha,alpha'-carbon atoms by Pd-catalyzed cross-coupling reactions with heteroarylmetals and by an S(N)Ar reaction with hexafluorobenzene. The experimentally observed results (NMR spectroscopy, X-ray analysis, UV/Vis absorption/fluorescence spectroscopy, and cyclic/differential-pulse voltammetry) have revealed that the structural, optical, and electrochemical properties of the bithiophene-fused benzo[c]phospholes vary considerably depending on the pi-conjugation modes at the bithiophene subunits and the substituents of the heterocyclopentadiene components. The appropriately ring-annulated sigma(3)-P derivatives and sigma(4)-P-AuCl complexes were found to emit fluorescence in the orange-red region, and the sigma(4)-P-oxo derivatives proved to undergo reversible one-electron reduction at -1.4 to -1.8 V (vs ferrocene/ferrocenium). These results indicate that the bithiophene-fused benzo[c]phospholes possess narrow HOMO-LUMO gaps and low-lying LUMOs, which was confirmed by density functional theory calculations of their model compounds. The time-of-flight measurement of an ITO/benzo[c]phosphole/Al device showed that the electron mobility in the P-oxo derivative is one-order higher than that in Alq(3) at low electric fields. The present study demonstrates that the arene-fused benzo[c]phosphole skeleton could be a highly promising platform for the construction of a new class of phosphole-based optoelectrochemical materials.     

Fluoro aromatic imine nickel(0) complexes: Synthesis and structural studies

The reaction of [Ni(dippe)]₂(μ-H)₂ with a series of fluoroaromatic imines affords nickel(0) complexes of the type [(dippe)Ni(η²-C,N)-PhHCNR′Ph], dippe = 1,2-bis(diisopropylphosphine)ethane. Solution NMR experiments as well as X-ray diffraction studies confirmed the π-coordination of the ligand through the CN moiety; the resulting complex found to adopt a distorted tetrahedral geometry around the nickel center. The compounds are thermally stable and decomposition is only observed after long periods of heating above 150 °C.     

Lipids and lipopolysaccharides of the genusFlavobacterium

The fatty acid compositions of the free lipids of three strains and the monosaccharide compositions of the lipopolysaccharides of four strains of new species of microorganisms of the genusFlavobacterium have been studied. The acidic nature of the polysaccharides of the LPSs of the microorganisms studied has been shown.Pacific Ocean Institute of Bioorganic Chemistry of the Far Eastern Scientific Center of the USSR Academy of Sciences, Vladivostok, and Institute of Microbiology of the USSR Academy of Sciences, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 564–567, September–October, 1986.     

Spectroscopic and structural study of the ambazone hydrochloride

Ambazone, a well-known antimicrobial compound, presents also oncostatic properties. The solid form, obtained by using solvent-drop grinding procedure, was characterized by using several physical techniques such as FTIR, X-ray photoelectron spectroscopy, ¹³C NMR and ¹⁵N NMR spectroscopies, thermal analysis, X-ray powder diffraction and mass spectrometry. Based on these data, it was demonstrated that an ambazone–hydrochloride was obtained: new vibrations corresponding to NH₂ ⁺ were identified. DTA–TG–DSC and MS data revealed that a new crystal type has been obtained. X-ray diffraction data allowed the determination of the lattice parameters and the most probable space group P _21/c was established also with only one molecule per asymmetric unit.