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11.
G. Baud J.P. Besse R. Chevalier B.L. Chamberland 《Journal of solid state chemistry》1979,28(2):157-162
The compound SrxReO3(0,4 ? X ? 0,5) has been prepared under high-pressure and high-temperature conditions (50 kbar, 900°C). Its structure (cubic KSbO3 type, a = 9.192Å, space group Im3) was solved using conventional methods from 819 unique reflections collected on an automatic four-circle diffractometer. The framework formed by ReO6 octahedra pairs definites, along (111) axis, tunnels occupied by Sr2+ ions. These strontium atoms are randomly distributed (occupancy factor = 0.30) on the 16f positions of the Im3 space group. 相似文献
12.
Stowers MA van Wuijckhuijse AL Marijnissen JC Scarlett B van Baar BL Kientz CE 《Rapid communications in mass spectrometry : RCM》2000,14(10):829-833
Matrix-assisted laser desorption/ionization (MALDI) mass spectra were obtained from single biological aerosol particles using an aerosol time-of-flight mass spectrometer (ATOFMS). The inlet to the ATOFMS was coupled with an evaporation/condensation flow cell that allowed the aerosol to be coated with matrix material as the sampled stream entered the spectrometer. Mass spectra were generated from aerosol composed either of gramicidin-S or erythromycin, two small biological molecules, or from aerosolised spores of Bacillus subtilis var niger. Three different matrices were used: 3-nitrobenzyl alcohol, picolinic acid and sinapinic acid. A spectrum of gramicidin-S was generated from approximately 250 attomoles of material using a molar ratio of 3-nitrobenzyl alcohol to analyte of approximately 20:1. A single peak, located at 1224 Da, was obtained from the bacterial spores. The washing liquid and extract solution from the spores were analyzed using electrospray mass spectrometry and subsequent MS/MS product ion experiments. This independent analysis suggests that the measured species represents part of the B. subtilis peptidoglycan. The on-line addition of matrix allows quasi-real-time chemical analysis of individual, aerodynamically sized particles, with an overall system residence time of less than 5 seconds. These results suggest that a MALDI-ATOFMS can provide nearly real-time identification of biological aerosols. Copyright 2000 John Wiley & Sons, Ltd. 相似文献
13.
B.L. Chamberland 《Journal of solid state chemistry》1973,7(4):377-384
Two new monoclinic V2O4 phases were prepared at high pressure from the regular monoclinic (M1) form of V2O4. The unit cell dimensions for the unmodified monoclinic (M2) phase are: a = 9.083, b = 5.763, c = 4.532 Å, and β = 91.30°. The space group is consistent with the crystallographic data. The new vanadium dioxide exhibited a structural transition and an abrupt, reversible change in resistivity (approx. 4 orders of magnitude) at 66°C similar to that observed in M1-type V2O4. This new form of V2O4 is believed to be stabilized by chemical and structural defects. Controlled substitution of V5+ for V4+ in the structure led to yet another monoclinic (M3) phase. This phase is closely related to the M2 phase. The M3 unit cell dimensions are: a = 4.506, b = 2.899, c = 4.617 Å, and β = 91.79°, having the space group . The substitution of V3+ yielded only monoclinic (M1) derivatives. The modified products have varied semiconductor to metal transition temperatures which depend on the type and amount of substitution and defect structure. 相似文献
14.
Consider the problem of heat flow in a convex domain in ℝn with Dirichlet boundary condition and constant initial temperature. We show that the solution has a fixed hot spot if the domain is invariant under the action of an essential symmetry group. © 1997 by B. G. Teubner Stuttgart–John Wiley & Sons Ltd. 相似文献
15.
G B Ouellette R P Baayen H Chamberland M Simard D Rioux P M Charest 《Microscopy and microanalysis》2004,10(4):449-461
Antibodies to detect pectin in present investigations attached to distinct fibrils in vessel lumina. In carnation infected with an isolate of Fusarium oxysporum f.sp., labeling of pathogen cells also occurred; in a resistant cultivar (cv.), it was coincident with proximate pectin fibrils and linked to altered fungal walls, which was the opposite in the susceptible cv., indicating that hindrance of pathogen ability to degrade pectin may be related to resistance. Labeling of the fungus in culture was nil, except in media containing pectin, showing that pectin is not native to the pathogen. Labeling of fungal walls for cellulose in elm (inoculated with Ophiostoma novo-ulmi) and carnation also occurred, linked to adsorbed host wall components. The chitin probe often attached to dispersed matter, in vessel lumina, traceable to irregularly labeled fungal cells and host wall degradation products. With an anti-horseradish peroxidase probe, host and fungal walls were equally labeled, and with a glucosidase, differences of labeling between these walls were observed, depending on pH of the test solution. Fungal extracellular matter and filamentous structures, present in fungal walls, predominantly in another elm isolate (Phaeotheca dimorphospora), did not label with any of the probes used. However, in cultures of this fungus, extracellular material labeled, even at a distance from the colony margin, with an anti-fimbriae probe. 相似文献
16.
CdIr(OH)6 and ZnIr(OH)6 were isolated and characterized in the process of synthesizing new ternary oxides of the platinum-group metals by means of thermal decomposition of hydroxide intermediates. Both compounds crystallize with an ordered ReO3-type structure. CdIr(OH)6 is tetragonal with a = 7.86 Å and c = 7.91 Å. It is a magnetically dilute insulator. ZnIr(OH)6 is cubic with a = 7.64 Å. It is an insulator with anomalous magnetic behavior. The cadmium and zinc iridium hexahydroxides decompose at 180 and 170°C, respectively. 相似文献
17.
The solid state reaction of VO2 and CdO yielded a phase of unknown structure, which transforms to CdVO3(I) after treatment under 60–65 kbar pressure at 1200°C. The high-pressure product was characterized by crystallographic, electrical and magnetic properties. CdVO3(I) is an orthorhombic perovskite-type compound and a metallic conductor, exhibiting Pauli paramagnetic behavior. In contrast, the ambient pressure phase displays Curie-Weiss magnetic behavior above 77°K. 相似文献
18.
Stereochemical elucidation and total synthesis of dihydropacidamycin D, a semisynthetic pacidamycin.
C G Boojamra R C Lemoine J C Lee R Léger K A Stein N G Vernier A Magon O Lomovskaya P K Martin S Chamberland M D Lee S J Hecker V J Lee 《Journal of the American Chemical Society》2001,123(5):870-874
Hydrogenation of the C(4') exocyclic olefin of the pacidamycins has been shown to produce a series of semisynthetic compounds, the dihydropacidamycins, with antimicrobial activity similar to that of the natural products. Elucidation of stereochemistry in the pacidamycins has been completed through a campaign of natural product degradation experiments in combination with the total synthesis of the lowest-molecular weight dihydropacidamycin, dihydropacidamycin D. The stereochemical identities of the tryptophan and two alanine residues contained in pacidamycin D have been shown to be of the natural (S) configuration, and the unique 3-methylamino-2-aminobutyric acid contained in this series of antibiotics has been shown to be of the (2S,3S) configuration. Finally, the stereochemistry obtained by hydrogenation of the C(4')-C(5') exocyclic olefin has been shown to be (R) at the C(4') nucleoside site. 相似文献
19.
As is well known, the stability of a dynamical system in two dimensions may be demonstrated in a very intuitive fashion from the existence of a suitable positive-definite Liapunov function, providing the contours of this function in a neighborhood of the stable point are Jordan curves. It is shown that the Liapunov function will certainly have this property if the stable point is an isolated stationary point in the sense of the Clarke calculus, but a counterexample is given if this assumption is weakened to the stable point being an isolated local extremum.This work was carried out with the support of the Natural Sciences and Engineering Council of Canada, which is gratefully acknowledged. 相似文献
20.