| 1. |
- Martínez, Claudia, et al.
(författare)
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Extraction Kinetics of Neem Seed Flakes
- 1998
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Ingår i: IACChE'98. - Mayagüez, Puerto Rico : University of Puerto Rico at Mayagüez (UPRM).
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Konferensbidrag (refereegranskat)
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| 2. |
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| 3. |
- Laihonen, Sari J., et al.
(författare)
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Crystal structure and morphology of melt-crystallized poly(propylene-stat-ethylene) fractions.
- 1997
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Ingår i: Polymer. - 0032-3861 .- 1873-2291. ; 38:2, s. 371-377
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Tidskriftsartikel (refereegranskat)abstract
- Crystallinity, crystal structure and lamellar thickness in melt-crystallized samples of poly(propylene-stat-ethylene) fractions with 2.7–11.0 mol% ethylene comonomer and of approximately constant tacticity were assessed by wide- and small-angle X-ray scattering, differential scanning calorimetry and infra-red spectroscopy. Most of the samples were crystallized under isothermal conditions at 373 K. In comparison with an isotactic homopolymer of polypropylene, the copolymers showed lower crystallinity, melting enthalpy and average length of 3/1 helices, a slightly larger unit cell, a longer long period and an invariant lamellar thickness. The X-ray crystallinity of the copolymers remained approximately constant with increasing ethylene content, whereas the γ-crystallinity increased and the heat of fusion decreased moderately. It is suggested that the ethylene units are partially included in the crystals, and that this causes the invariance in crystallinity and crystal thickness. The observed gradual decrease in average 3/1 helix length with increasing ethylene content as assessed by infra-red spectroscopy is in accordance with this suggestion.
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| 5. |
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| 6. |
- Rönnow, Daniel, et al.
(författare)
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Piezo-optical coefficients of ZnSe and ZnTe above the fundamental gap
- 1999
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 59:8, s. 5581-5590
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Tidskriftsartikel (refereegranskat)abstract
- The piezo-optical coefficients P11-P12 and P44 have been measured for ZnSe and ZnTe above the fundamental gap (in the energy ranges 2.6-5.5 eV and 2.0-5.5 eV, respectively) by using reflectance difference spectroscopy. The measured spectra of P11-P12 and P44 show good Kramers-Kronig consistency between their real and imaginary parts. Values for the deformation potentials D1 5, D3 3, and D3 5 for the E1 and E1 + Δ1 transitions were estimated by fitting the spectral dependence of P11-P12 and P44 to analytical line shapes based on a one-electron approximation.
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| 7. |
- Tórrez, Norvin, et al.
(författare)
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Modelling and Simulation of Crossflow Moving Bed Grain Dryers
- 1998
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Ingår i: Drying Technology. - : Informa UK Limited. - 0737-3937 .- 1532-2300. ; 16:9-10, s. 1999-2015
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Tidskriftsartikel (refereegranskat)abstract
- The drying of grain in dryers of a crossflow moving bed type was theoretically and experimentally studied. Two different dryer configurations were analyzed, a dryer with central air distribution and another with multiple air duels. Experimental information was obtained in pilot-size dryers. A mathematical model to simulate the process was developed. Hindered drying was accounted for by using the concept of relative drying rate. An adjustable factor, specific to the dryers, was used to account for the uncertainties of the contact area and the transfer coefficients encountered in the literature. Agreement between experimental results and simulations was fairly good. Simulations showed that distance between inlet air and outlet devices, air to solid flow ratio and dryer height to cross section ratio have great influence on the process. The mathematical model may be a useful tool for process exploration and optimization of this type of dryers.
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| 8. |
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| 9. |
- Casas, Jesús M., et al.
(författare)
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Bioleaching model of a copper-sulfide ore bed in heap and dump configurations
- 1998
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer Science and Business Media LLC. - 1073-5615 .- 1543-1916. ; 29:4, s. 899-909
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Tidskriftsartikel (refereegranskat)abstract
- A two-dimensional (2-D) model for a heap or dump bioleaching of a copper ore containing mainly chalcocite and pyrite has been developed. The rate of the mineral sulfide dissolution was related to the rate of oxidation by bacteria attached onto the ore surface. The latter was calculated using the model of Michaelis-Menten, where both temperature and dissolved oxygen in the leach solution were taken into account by the kinetic equation. Oxygen transport through the ore bed was associated with natural air convection originating from the decrease in gas density inside the ore bed, which was attributable not only to heating, but also to humidification and decrease in the oxygen concentration. The model was used to estimate air-velocity fields and profiles of temperature and oxygen concentrations as well as mineral conversions during the bioleaching operation for ore beds with different pyrite contents, bacterial populations, widths, heights, and permeabilities. The model provides a useful tool for the design, improvement, and optimization of industrial operating conditions.
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