| 1. |
- Taherzadeh Esfahani, Mohammad, 1965, et al.
(författare)
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Continuous Cultivation of Dilute-Acid Hydrolysates to Ethanol by Immobilized Saccharomyces cerevisiae
- 2001
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Ingår i: Applied Biochemistry and Biotechnology. - 0273-2289 .- 1559-0291. ; 95:1, s. 45-57
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Tidskriftsartikel (refereegranskat)abstract
- The continuous cultivation of immobilized Saccharomyces cerevisiae CBS 8066 on dilute-acid hydrolysates of forest residuals was investigated. The yeast cells were immobilized in 2–4% Ca-alginate beads. The 2% beads were not stable. However, the 3 and 4% beads were stable for at least 3 wk when an extra resource of calcium ions was available in the medium. The continuous cultivation of a dilute-acid hydrolysate by the immobilized cells at dilution rates of 0.3, 0.5, and 0.6 h−1 resulted in 86, 83, and 79% sugar consumption, respectively, and an ethanol yield between 0.45 and 0.48 g/g. The hydrolysate was fermentable at a dilution rate of 0.1 h−1 in a free-cell system but washed out at a dilution rate of 0.2 h−1. The continuous cultivation of a more inhibiting hydrolysate was not successful by either free- or immobilized-cell systems even at a low dilution rate of 0.07 h−1. However, when the hydrolysate was overlimed, it was fermentable by the immobilized cells at a dilution rate of 0.2 h−1.
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| 2. |
- Jagers, Peter, 1941, et al.
(författare)
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Branching processes in near-critical random environments
- 2004
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Ingår i: Journal of Applied Probability. - : Cambridge University Press (CUP). - 0021-9002 .- 1475-6072. ; 41A, s. 17-23
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Tidskriftsartikel (refereegranskat)abstract
- Branching processes are studied in random environments that are influenced by the population size and approach criticality as the population gets large. Results are applied to the polymerase chain reaction (PCR), which is empirically known to exhibit first exponential and then linear growth of molecule numbers.
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| 3. |
- Navrátil, Marián, et al.
(författare)
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On-line multisensor monitoring of yogurt and Filmjolk fermentations on production scale
- 2004
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 52:3, s. 415-420
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Tidskriftsartikel (refereegranskat)abstract
- Near-infrared (NIR) spectrometry and electronic nose (EN) data were used for on-line monitoring of yogurt and filmjölk (a Swedish yogurt-like sour milk) fermentations under industrial conditions. The NIR and EN signals were selected by evaluation of principal component analysis loading vectors and further analyzed by studying the variability of the selected principal components. First principal components for the NIR and the EN signals were used for on-line generation of a process trajectory plot visualizing the actual state of fermentation. The NIR signals were also used to set up empirical partial least-squares (PLS) models for prediction of the cultures' pH and titratable acidity (expressed as Thorner degrees, °T). By using five or six PLS factors the models yielded acceptable predictions that could be further improved by increasing the number of reliable and precise calibration data. The presented results demonstrate that the fusion of the NIR and EN signals has a potential for rapid on-line monitoring and assessment of process quality of yogurt fermentation.
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| 4. |
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| 5. |
- Agarwal, Parminder, et al.
(författare)
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Effect of polymeric additives on calcium carbonate crystallization as monitored by nephelometry
- 2004
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 4:3, s. 479-483
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Tidskriftsartikel (refereegranskat)abstract
- The effect of polymaleimide polymers on calcium carbonate crystallization was studied using nephelometry. Induction time and percent growth inhibition were determined for polymeric additives from the nephelometric data. The polymaleimide synthesized by KOH-initiated polymerization exhibited the greatest growth inhibition and longest nucleation time among the polymers investigated. Raman spectroscopy was used to determine the calcium carbonate polymorph formed in the presence of these polymeric additives.
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| 6. |
- Agarwal, Parminder, et al.
(författare)
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In situ monitoring of calcium carbonate polymorphs during batch crystallization in the presence of polymeric additives using Raman spectroscopy
- 2003
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 3:6, s. 941-946
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Tidskriftsartikel (refereegranskat)abstract
- Polycarboxylic acids are well-known to affect calcium carbonate crystallization. Agarwal et al. (Ind. Eng. Chem. Res. 2003, in press) reported previously the synthesis of polymaleimide by a variety of techniques and initiators. In the present work, the effect of these polymers on calcium carbonate crystallization was studied by a variety of techniques. Crystallization experiments were carried out in a 1-L LABMAX automated batch reactor, and the concentration of calcium in solution was determined in real time. Raman spectroscopy was used to determine the relative amount of various calcium carbonate polymorphs as the crystallization occurred. However, Raman spectroscopy is a scattering technique, which may make it surface selective, and therefore results from solids may not be representative of bulk of sample. X-ray diffraction (XRD) was used to compare the results obtained by Raman spectroscopy. Peak intensity ratios were used for both Raman spectroscopy and XRD for calibration and measurement purposes. The results obtained by these two techniques for final percent vaterite for calcium carbonate crystallization in the presence of polymeric additives were in agreement within 2%. Therefore, use of Raman spectroscopy for in situ measurement of polymorph composition during calcium carbonate crystallization appears accurate. Scanning electron microscopy (SEM) data were useful in understanding the crystal morphology and to determine crystal size.
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| 7. |
- Agarwal, Parminder, et al.
(författare)
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Synthesis and characterization of polymaleimide
- 2003
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 42:13, s. 2881-2884
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Tidskriftsartikel (refereegranskat)abstract
- Simplified syntheses of polymaleimide employing anionic polymerization (from the melt and from solution) and metal compound-alcohol initiators such as PbO, SnO, tin bis(2-ethyl hexanoate) in the presence of tert-butyl benzyl alcohol are presented. The resulting polymers contain a combination of C-N- and C-C-connected monomers. Preliminary structures of the polymers were determined using NMR spectroscopy. The ratio of C-N- and C-C-connected monomers was determined, and the percentage of C-N-connected monomer units was found to vary from 40 to 80%, with the higher percentage resulting from anionic polymerization. The molecular weights of the polymers, as determined by gel permeation chromatography (GPC) with aqueous mobile phase and sodium polyacrylates standards, ranged between 1100 and 4200 for anionic polymerization and were about 11 500 for metal oxide-alcohol initiated polymerization. Solution-phase properties of the polymaleimides were evaluated by calcium chelation and precipitation inhibition studies. On the basis of the measured properties of these polymers, they are proposed as biodegradable, low-impact detergent additives to substitute currently used compounds.
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| 8. |
- Andraous, Johnny I., et al.
(författare)
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Effect of liquefaction enzymes on methanol concentration of distilled fruit spirits
- 2004
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Ingår i: American Journal of Enology and Viticulture. - 0002-9254 .- 1943-7749. ; 55:2, s. 199-201
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Tidskriftsartikel (refereegranskat)abstract
- Liquefaction enzymes are often used during fermentation of fruit mashes to improve the yield of ethanol and the ability to pump the mash. The liquefaction enzymes hydrolyze pectin, but in addition to the desired pectin hydrolysis activity, the enzymes also have pectinesterase activity which hydrolyzes the methyl ester in pectin resulting in methanol formation. Fermentations of various apple varieties and Bartlett pears were conducted using liquefaction enzymes. The resulting distilled products contained concentrations of methanol above the legal limit of 280 mg/100 mL of 40% ethanol, with the observed methanol concentrations in a range between 320 and 656 mg/100 mL of 40% ethanol. In contrast to the undesired increase in methanol concentration, the enzymes provide only a marginal increase in ethanol yield. The results indicate that liquefaction enzymes should be used with caution for pomace fruit and that methanol monitoring should be implemented if these enzymes are used for commercial products.
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| 9. |
- Falcon, Javier A., et al.
(författare)
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In situ monitoring of antisolvent addition crystallization with principal components analysis of Raman spectra
- 2004
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 4:3, s. 457-463
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Tidskriftsartikel (refereegranskat)abstract
- Fiber optic Raman spectroscopy was used for in situ monitoring of antisolvent addition crystallization of progesterone. Raman spectral features of the solute and the antisolvent were subjected to principal components analysis (PCA) to attempt to obtain information that is not readily apparent from the raw spectral data. For the system utilized, PCA was able to distinguish spectral features from the solute in solution, the solute crystals, and the antisolvent. Furthermore, PCA was capable of detecting subtle changes in the spectral data (as the addition of antisolvent progressed) that could be used as a warning for the onset of crystallization. The current study demonstrates the advantages that can be gained by combining PCA with Raman spectroscopy for monitoring crystallizations in situ.
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| 10. |
- Falcon, Javier A., et al.
(författare)
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Monitoring of antisolvent addition crystallization with Raman spectroscopy
- 2003
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 3:6, s. 947-952
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Tidskriftsartikel (refereegranskat)abstract
- Fiber optic Raman spectroscopy was used for in situ monitoring of antisolvent addition crystallization of cortisone acetate. Raman spectral features of the solvent, the antisolvent, and the solute were monitored to measure the relative concentration of the components. Different rates of antisolvent addition were monitored and the resulting solid-state form was characterized using Raman spectroscopy and DSC. Raman spectroscopy was used to monitor dehydration during storage of the product crystals. The current study demonstrates the advantages of using Raman spectroscopy to monitor the solution phase during crystallization and simultaneously monitoring the solid-state form.
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