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- Hirschauer, B, et al.
(författare)
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CeO2 on Si(111) 7 X 7 and Si(111)-H 1 X 1, an interface study by high-resolution photoelectron spectroscopy
- 1999
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 148:3-4, s. 164-170
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Tidskriftsartikel (refereegranskat)abstract
- The formation of the CeO2-Si(111) interface was studied by high-resolution photoelectron spectroscopy. It is shown that CeO2 and Si(111) forms a highly reactive: interface with a strong interdiffusion of Si into the CeO2. A passive silicon surface formed by saturating the Si dangling bonds with hydrogen is considerably less reactive. Defects on the surface, however, act as nucleations centres for reactions of a Si:Ce:O matrix. Oxygen leaves the surface at about 800 degrees C and at 1000 degrees C a surface reconstruction of Si(111)-Ce 2 X 2/root 3 X root 3 is formed. (C) 1999 Elsevier Science B.V. All rights reserved.
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- Jacobson, GB, et al.
(författare)
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Supercritical fluid extraction of C-11-labeled metabolites in tissue using supercritical ammonia
- 1997
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Ingår i: ANALYTICAL CHEMISTRY. - : AMER CHEMICAL SOC. - 0003-2700. ; 69:3, s. 275-280
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Tidskriftsartikel (refereegranskat)abstract
- Supercritical fluid extraction (SFE) of C-11-labeled tracer compounds and their metabolites from biological tissue was performed using supercritical ammonia in an attempt to develop a rapid extraction procedure that allowed subsequent analysis of the lab
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- Stolte, W.C., et al.
(författare)
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The K-shell Auger decay of atomic oxygen
- 1997
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - 0953-4075. ; 30:20, s. 4489-4497
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Tidskriftsartikel (refereegranskat)abstract
- Relative photoionization cross sections for O+ and O2+ produced by the Auger decay of a 1s hole in atomic oxygen were measured by using synchrotron radiation between 525 and 553 eV. Energies and quantum defects of the members of the two Rydberg series converging to [1s]2s22p4(4P) and [1s]2s22p4(2P) ionization thresholds were determined. In addition, the 2P and 4P ionization thresholds were calculated from the two Rydberg series. The 182 meV resolution of the monochromator allowed a detailed study over both thresholds revealing evidence for post-collision interaction and allowing a comparison of the ionization continuum above both 2P and 4P thresholds with that of the ionization continuum above the Ar L2 and L3 edges. This comparison indicates that the lifetimes of the Ar(2p) and O(1s) hole states are approximately the same.
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- Wang, G.X., et al.
(författare)
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Oxidation mechanism of Si3N4-bonded SiC ceramics by CO, CO2 and steam
- 1998
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 33:5, s. 1309-1317
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a theoretical and experimental investigation into the oxidation reactions of Si3N4-bonded SiC ceramics. Such ceramics which contain a small amount of silicon offer increased oxidation and wear resistance and are widely used as lining refractories in blast furnaces. The thermodynamics of oxidation reactions were studied using the JANAF tables. The weight gain was measured using a thermogravimetric analysis technique to study the kinetics. The temperature range of oxidation measurements is from 1073 to 1573 K and the oxidation atmosphere is water vapour, pure CO and CO-CO2 gas mixtures with various CO-to-CO2 ratios. Thermodynamic simulations showed that the oxidation mechanism of Si3N4-bonded SiC ceramics is passive oxidation and all components contribute to the formation of a silica film. The activated energies of the reactions follow the sequence Si3N4 > SiC > Si. The kinetic study revealed that the oxidation of Si3N4-bonded SiC ceramics occurred in a mixed regime controlled by both interface reaction and diffusion through the silica film. Under the atmosphere conditions prevailing in the blast furnace, this ceramic is predicted to be passively oxidized with the chemical reaction rate becoming more dominant as the CO concentration increases
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- Yuan, XiMing, et al.
(författare)
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The establishment of two cell lines from a mouse uterine cervical carcinoma (U14) and their metastatic phenotype changes
- 1995
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Ingår i: Clinical and Experimental Metastasis. - 0262-0898 .- 1573-7276. ; 13:6, s. 463-73
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies the heterogeneity of metastatic potential of murine cervical carcinoma (U14). Two cell lines, P11-90 and L10-90, were established from a pulmonary metastatic substrain (U14AP11) and a lymphatic metastatic substrain (U14AL10), which were selected from U14 in vivo after 11 and 10 passages, respectively. The biologic differences between the two cell lines are as follows. (1) The cells of the P11-90 line grow more rapidly compared with the L10-90 line. From the 40th passage the medium pH was different. (2) The median number of chromosomes in P11-90 and L10-90 was 72 and 64, respectively; the rates of gap aberration were 88% and 78%, respectively. (3) The number of T lymphocytes and T helper lymphocytes in the peripheral blood from hosts with P11-90 were higher than that of hosts transplanted with L10-90, but the number of B lymphocytes in the latter was larger than that in the former. (4) The metastatic potential of each cell line partially decreased compared to the relative tumor substrain, but their organ preference still remained and the transplant locations, axillary or footpad, had a prominent influence on their metastatic behavior. To observe the effects of metastatic target organs on the metastatic phenotypes of tumor cells, as well as to explore a method for the establishment and maintenance of the metastatic organ preference of tumor cells, conditioned medium (CM) from pulmonary or lymphatic node diploid cells was added to the culture medium of P11-90 and L10-90. Two sublines, P + P11-90 and Ln + L10-90, were thus established. Using stereological methods we found that the majority of P + P11-90 cells became larger and their nuclei also increased in size compared with their parental lines, but the majority of Ln + L10-90 cells became smaller in size, though the nuclei were enlarged. The pulmonary metastatic rate and lymphatic metastatic rate of P + P11-90, as well as the lymphatic metastatic rate of Ln + L10-90, were restored dramatically. The results suggest that by taking advantage of the interaction between tumor cells and the CM of host cells the metastatic potential of tumor cell lines can be maintained in vitro. Our work may offer an experimental model for the manipulation of metastasis of cell lines coming from the same parent strain but with different metastatic potentials.(ABSTRACT TRUNCATED AT 400 WORDS)
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