| 41. |
- Westin, K. J., et al.
(författare)
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Nucleation of calcium carbonate in presence of citric acid, DTPA, EDTA and pyromellitic acid
- 2005
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 282:2, s. 370-379
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Tidskriftsartikel (refereegranskat)abstract
- The influence of four calcium complexing additives, i.e., citric acid (CIT), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA) and pyromellitic acid (PMA), and their concentration on the induction time of calcium carbonate nucleation has been studied. The experiments were performed by rapidly mixing a sodium carbonate solution and a calcium chloride solution of various concentrations. The induction time was obtained by recording the white light absorption of the solution. Chemical speciation was used to estimate the initial thermodynamic driving force of each experiment. The induction time was found to increase with additive concentration. The effect varies from one additive to another. CIT causes the greatest increase in induction time and PMA the least. Using classical nucleation theory the experimental data were evaluated in terms of the interfacial energy. fit pure water a value of 37.8 mJ m(-2) was obtained, showing good agreement with other works. CIT DTPA and EDTA caused a notable increase of the interfacial energy at a concentration of 0.5 mmol l(-1). PMA does not appear to have any effect at all on the interfacial energy. Different mechanisms for the influence of the additives on the measured induction time and on the estimated interfacial energy are discussed.
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| 42. |
- Westin, K. J., et al.
(författare)
-
Precipitation of calcium carbonate in the presence of citrate and EDTA
- 2003
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Ingår i: Desalination. - 0011-9164 .- 1873-4464. ; 159:2, s. 107-118
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Tidskriftsartikel (refereegranskat)abstract
- The influence of process conditions such as feed rate, calcium/carbonate ratio, pH, complexing agents [ethylenediaminetetraacetic acid (EDTA), citrate (CIT)] and their concentration on the average particle size and shape of precipitated calcium carbonate was studied. The precipitation was performed in a semi-batch operated agitated vessel at constant pH by adding sodium hydrogen carbonate to a solution containing calcium chloride. In the absence of a complexing agent, agglomerates of needle-shaped crystals, probably aragonite, are obtained. Increasing feed time and the calcium/carbonate ratio increases the average particle size, whereas the opposite effect is observed for increasing pH. The observations can be related to the level of supersaturation. In the presence of complexing agents and at a concentration ratio of calcium vs. a complexing agent of 6, differently shaped and smaller particles were obtained. Furthermore, the effect of the other parameters on particle size becomes much weaker in the presence of complexing agents. In the presence of EDTA mostly spherical particles were obtained, and in the presence of citrate mainly rhombic particles corresponding to calcite were obtained. The effect on particle shape and size is attributed to interactions of the complexing agents with the faces of the crystalline calcium carbonate.
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| 43. |
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| 44. |
- Worku, Z. A., et al.
(författare)
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Modelling and understanding powder flow properties and compactability of selected active pharmaceutical ingredients, excipients and physical mixtures from critical material properties
- 2017
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Ingår i: International Journal of Pharmaceutics. - : Elsevier. - 0378-5173 .- 1873-3476. ; 531:1, s. 191-204
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Tidskriftsartikel (refereegranskat)abstract
- The development of solid dosage forms and manufacturing processes are governed by complex physical properties of the powder and the type of pharmaceutical unit operation the manufacturing processes employs. Suitable powder flow properties and compactability are crucial bulk level properties for tablet manufacturing by direct compression. It is also generally agreed that small scale powder flow measurements can be useful to predict large scale production failure. In this study, predictive multilinear regression models were effectively developed from critical material properties to estimate static powder flow parameters from particle size distribution data for a single component and for binary systems. A multilinear regression model, which was successfully developed for ibuprofen, also efficiently predicted the powder flow properties for a range of batches of two other active pharmaceutical ingredients processed by the same manufacturing route. The particle size distribution also affected the compactability of ibuprofen, and the scope of this work will be extended to the development of predictive multivariate models for compactability, in a similar manner to the approach successfully applied to flow properties.
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| 45. |
- Yu, X., et al.
(författare)
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A compartmental CFD-PBM model of high shear wet granulation
- 2017
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Ingår i: AICHE Journal. - : Wiley. - 1547-5905 .- 0001-1541. ; 63:2, s. 438-458
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Tidskriftsartikel (refereegranskat)abstract
- © 2016 American Institute of Chemical EngineersThe conventional, geometrically lumped description of the physical processes inside a high shear granulator is not reliable for process design and scale-up. In this study, a compartmental Population Balance Model (PBM) with spatial dependence is developed and validated in two lab-scale high shear granulation processes using a 1.9L MiPro granulator and 4L DIOSNA granulator. The compartmental structure is built using a heuristic approach based on computational fluid dynamics (CFD) analysis, which includes the overall flow pattern, velocity and solids concentration. The constant volume Monte Carlo approach is implemented to solve the multi-compartment population balance equations. Different spatial dependent mechanisms are included in the compartmental PBM to describe granule growth. It is concluded that for both cases (low and high liquid content), the adjustment of parameters (e.g. layering, coalescence and breakage rate) can provide a quantitative prediction of the granulation process. © 2016 American Institute of Chemical Engineers AIChE J, 63: 438–458, 2017.
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| 46. |
- Zhou, Guang-Qian, et al.
(författare)
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The Drosophila ortholog of the endolysosomal membrane protein, endolyn, regulates cell proliferation.
- 2006
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Ingår i: J Cell Biochem. - 0730-2312. ; 99:5, s. 1380-96
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Tidskriftsartikel (refereegranskat)abstract
- Endolyn (CD164) is a sialomucin that regulates the proliferation, adhesion, and migration of human haematopoietic stem and progenitor cells. This molecule is predominately localized in endocytotic compartments, where it may contribute to endolysosomal biogenesis and trafficking. In order to more closely define the function of endolyn from an evolutionary view-point, we first analyzed endolyn orthologs in species ranging from insects, fish, and birds to mammals. The predicted molecular structures of the endolyn orthologs from these species are well conserved, particularly with respect to significant O-linked glycosylation of the extracellular domain, and the high degree of amino acid similarities within their transmembrane and cytoplasmic domains, with the latter possessing the lysosomal target signal, YXXphi. Focusing on Drosophila, our studies showed that the subcellular distribution of endolyn in non-polarized Drosophila S2 cells resembles that of its human counterpart in hematopoietic cells, with its predominant localization being within intracellular vesicles, while a small fraction occurs on the cell surface. Both Y --> A and L --> A mutations in the YHTL motif perturbed the normal subcellular distribution of Drosophila endolyn. Interestingly, embryonic and early larval development was often arrested in endolyn-deficient Drosophila mutants. This may partly be due to the role of endolyn in regulating cell proliferation, since knock-down of endolyn expression in S2 cells resulted in up to 50% inhibition of cell growth, with a proportion of cells undergoing apoptosis. Taken together, these results demonstrate that endolyn is an evolutionarily conserved sialomucin fundamentally involved in cell proliferation in both the human and Drosophila melanogaster. 2006 Wiley-Liss, Inc.
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