| 1. |
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| 2. |
- Babushkin, Oleg, et al.
(författare)
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Thermal expansion of hot isostatically pressed hydroxyapatite
- 1994
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Ingår i: Journal of Materials Chemistry. - 0959-9428 .- 1364-5501. ; 4:3, s. 413-415
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Tidskriftsartikel (refereegranskat)abstract
- A dense and transparent hydroxyapatite produced by hot isostatic pressing was investigated with respect to its stability and thermal expansion behaviour in the range 20–1150 °C. The evaluation was made by high-temperature X-ray diffraction in a reconstructed test chamber with a BN sample holder and Pt as an internal (in situ) reference. No degradation of the hydroxyapatite was detected in the range investigated. The lattice parameters, a and c, were determined as a function of temperature. The linear thermal expansion coefficient, determined by dilatometry, was 17.1 × 10–6°C–1, which agreed well with the value 17.3 × 10–6°C–1 obtained by X-ray diffraction.
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| 3. |
- Christakopoulos, Paul, et al.
(författare)
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Direct conversion of sorghum carbohydrates to ethanol by a mixed microbial culture
- 1993
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Ingår i: Bioresource Technology. - 0960-8524 .- 1873-2976. ; 45:2, s. 89-92
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Tidskriftsartikel (refereegranskat)abstract
- The carbohydrates of sweet sorghum were directly converted to ethanol by a mixed culture of Fusarium oxysporum F3 and Saccharomyces cerevisiae 2541. A number of factors affecting this bioconversion was studied. Optimum ethanol yields of 33·2 g/100 g of total sorghum carbohydrates, corresponding to 10·3 g/100 g of fresh stalks, were obtained. These values represented 68·6% of the theoretical yield based on total polysaccharides and exceeded that based on oligosaccharides of sorghum by 53·7%. The results demonstrated that more than half of the sorghum polysaccharides were directly fermented to ethanol, thus making the process worthy of further investigation.
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| 4. |
- Kim, Y J, et al.
(författare)
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A multiprotein mediator of transcriptional activation and its interaction with the C-terminal repeat domain of RNA polymerase II.
- 1994
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Ingår i: Cell. - 0092-8674 .- 1097-4172. ; 77:4, s. 599-608
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Tidskriftsartikel (refereegranskat)abstract
- A mediator was isolated from yeast that enabled a response to the activator proteins GAL4-VP16 and GCN4 in a transcription system reconstituted with essentially homogeneous basal factors and RNA polymerase II. The mediator comprised some 20 polypeptides, including the three subunits of TFIIF and other polypeptides cross-reactive with antisera against GAL11, SUG1, SRB2, SRB4, SRB5, and SRB6 proteins. Mediator not only enabled activated transcription but also conferred 8-fold greater activity in basal transcription and 12-fold greater efficiency of phosphorylation of RNA polymerase II by the TFIIH-associated C-terminal repeat domain (CTD) kinase, indicative of mediator-CTD interaction. A holoenzyme form of RNA polymerase II was independently isolated that supported a response to activator proteins with purified basal factors. The holoenzyme proved to consist of mediator associated with core 12-subunit RNA polymerase II.
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| 5. |
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| 6. |
- Li., J., et al.
(författare)
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Boundary Larmor Radius Effect on Electrostatic Waves
- 1991
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Ingår i: Physics of fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; B3, s. 3013-
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Tidskriftsartikel (refereegranskat)abstract
- The linearized Vlasov–Poisson equations, which combine to an integrodifferential equation for the perturbed electric potential, are used to investigate the effect of finite plasma size on the stability of electrostatic waves in a homogeneous plasma slab. The distortion of the gyromotion of the particles at the plasma boundary influences wave stability, a phenomenon termed the boundary Larmor radius (BLR) effect. The integrodifferential equation, treated as an eigenvalue problem, is discretized into a matrix dispersion equation by use of the Galerkin method and is then solved numerically. It is found that the ion Bernstein wave,which is undamped in an infinite homogeneous plasma, now becomes damped with a maximum damping rate of 0.35 ωci at rG/L (ion Larmor radius over wall distance)≊0.15. In general, the damping is less pronounced at shorter perpendicular wavelengths. It implies a necessity to take into account the BLR effect in the kinetic stability studies for sufficiently large ion Larmor radius in comparison to the characteristic dimension.
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| 7. |
- Li, J., et al.
(författare)
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Boundary Larmor Radius Effects
- 1990
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Ingår i: XVII European Conference on Controlled Fusion and Plasma Heating, Amsterdam, Netherlands, June 25-29, 1990. ; , s. 1836-
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Konferensbidrag (refereegranskat)
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| 8. |
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| 9. |
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| 10. |
- Li, J., et al.
(författare)
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Kinetic High-beta Equilibria and Stability in a Plasma Slab
- 1991
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Ingår i: Physics of fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; B3, s. 2506-
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Tidskriftsartikel (refereegranskat)abstract
- Self‐consistent, high‐beta kinetic equilibria are derived from the Vlasov equation for a plasma slab in a nonzero magnetic field with a density gradient and a gravitational field. It is shown that a magnetic field inhomogeneity and an electric field arise as necessary consequences of the high‐beta state. Hence the corresponding equilibrium forces should not be neglected in calculations of individual particle motion. Explicit expressions are derived for equilibrium quantities, useful, e.g., for large Larmor radius (LLR) studies of the Rayleigh–Taylor instability.
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| 11. |
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| 12. |
- Li, W.B., et al.
(författare)
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Mechanisms of indentation creep
- 1991
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Ingår i: Acta Metallurgica et Materialia. - 0956-7151. ; 39:12, s. 3099-3110
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Tidskriftsartikel (refereegranskat)abstract
- A physically-based theoretical model is developed for describing the phenomenon of indentation creep over the whole temperature range, from 300 K to melting. In agreement with experimental data collected, the model predicts that most materials, including ceramics, exhibit indentation creep at temperatures down to 300 K. It is established that the principal mechanism causing indentation creep is dislocation glide plasticity. The dominance of this mechanism over the whole temperature range is due to the very high stresses involved in indentation creep. If, however, the grain size is small (typically less than 0.3-0.4 μm) indentation creep may be dominated by grain boundary (Coble) diffusive creep instead. The implications of these results in terms of the design, forming and application of the so-called "hard materials" is discussed.
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| 13. |
- Li, Zheng, et al.
(författare)
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Minimum Variance Prediction for Linear Time-Varying Systems
- 1994
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Ingår i: IFAC Proceedings Volumes. ; 27:8
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Konferensbidrag (refereegranskat)abstract
- In this paper we study the problem of minimum variance prediction for linear time-varying systems. We consider the standard time-varying autoregression moving average (ARMA) model and develop a predictor which guarantees minimum variance prediction for a large class of linear time-varying systems. The predictor is developed based on a pseudocommutation technique for dealing with noncommutativity of linear time-varying operators in a transfer operator framework. We also show connections between this input-output predictor and the Kalman predictor via an example.
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| 14. |
- Navara, E., et al.
(författare)
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Investigation of microstructural changes occurring during warm working of manganese partitioned dual phase steel
- 1990
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Ingår i: Materials Science and Technology. - : Informa UK Limited. - 0267-0836 .- 1743-2847. ; 6:2, s. 151-155
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents results from studies using transmission and high resolution electron microscopy of as-received and warm worked manganese partitioned dual phase steel. A growing manganese enriched austenite grain shares two different boundaries with ferrite: (a) a stationary coherent boundary, replacing a stretch of the original ferrite/ferrite boundary, and (b) a migrating non-coherent boundary. This finding gives support to a previously described mechanism of the nucleation and growth of the manganese enriched austenite. The structure of the warm worked steel consists of recovered ferrite strengthened by substructure, and fine martensitic lathes separated by low angle boundaries which resulted from the transformation of deformed non-recrystallised austenite grains
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| 15. |
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