| 1. |
- Alemrajabi, Mahmood, 1989-, et al.
(författare)
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Separation of Rare-Earth Elements Using Supported Liquid Membrane Extraction in Pilot Scale
- 2022
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045.
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Tidskriftsartikel (refereegranskat)abstract
- The use of supported liquid membrane extraction for recovery and separation of rare-earth elements (REEs) has been investigated. Experiments have been carried out using the different configurations: (1) standard hollow fiber supported liquid membrane operation (HFSLM), (2) renewal liquid membrane operation (HFRLM), and (3) emulsion pertraction technology (EPT). The experiments were performed in pilot scale using a hollow fiber module with a mass transfer surface area of 8 m2. Synthetic feed solution was used with compositions based on a process for recovery of REE from an apatite concentrate. The total concentration of REE in the feed was varied from 1 to 22 mM REE and the pH was varied in the range 1.5–3.2. Di(2-ethylhexyl) phosphoric acid (D2HEPA) diluted in kerosene, 10% (v/v), was used as the organic membrane solution, and 3 M HCl was used as stripping solution. In supported liquid membrane extraction, the extraction performance is governed by both the kinetics of REE transport through the membrane and by thermodynamics. The effect of feed composition on the selectivity and transport of REE through the liquid membrane have been investigated. The results show that the liquid membrane is more selective toward the heavy REE at lower pH values and higher REE concentration. HFRLM shows a higher transport rate than HFSLM, while the HFSLM configuration gives a higher selectivity toward individual REE. The membrane performance in HFSLM configuration rapidly decays with time, while in the HFRLM and EPT configurations, the performance is much more stable. Possible mechanisms for decaying membrane performance are discussed, and gel formation is identified as being of significant importance. Gel formation is observed at an organic loading above ∼46% for Nd, 38% for Y, 46% for Dy, and 65% for Er. The work performed in this study serves as an initial step to demonstrate that HFRLM and EPT can provide stable operation and be feasible options for processing of REE liquors. A process flow diagram for the recovery of the REE, present in the apatite concentrate, in three fractions is proposed based on the results from this study.
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| 2. |
- Knævelsrud, Helene, et al.
(författare)
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Membrane remodeling by the PX-BAR protein SNX18 promotes autophagosome formation
- 2013
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Ingår i: Journal of Cell Biology. - : Rockefeller University Press. - 0021-9525 .- 1540-8140. ; 202:2, s. 331-349
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Tidskriftsartikel (refereegranskat)abstract
- The membrane remodeling events required for autophagosome biogenesis are still poorly understood. Because PX domain proteins mediate membrane remodeling and trafficking, we conducted an imaging-based siRNA screen for autophagosome formation targeting human PX proteins. The PX-BAR protein SNX18 was identified as a positive regulator of autophagosome formation, and its Drosophila melanogaster homologue SH3PX1 was found to be required for efficient autophagosome formation in the larval fat body. We show that SNX18 is required for recruitment of Atg16L1-positive recycling endosomes to a perinuclear area and for delivery of Atg16L1- and LC3-positive membranes to autophagosome precursors. We identify a direct interaction of SNX18 with LC3 and show that the pro-autophagic activity of SNX18 depends on its membrane binding and tubulation capacity. We also show that the function of SNX18 in membrane tubulation and autophagy is negatively regulated by phosphorylation of S233. We conclude that SNX18 promotes autophagosome formation by virtue of its ability to remodel membranes and provide membrane to forming autophagosomes.
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| 3. |
- Knævelsrud, Helene, et al.
(författare)
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The membrane-remodeling PX-BAR protein SNX18 is required for autophagy
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Autophagy is a catabolic pathway targeting cytoplasmic material for lysosomal degradation,thereby protecting cells from accumulation of toxic components and enabling cells to survivescarce nutrient supplies. Macroautophagy is characterized by the sequestration of cytoplasmicmaterial into double-membrane vesicles, but the membrane remodeling events required forformation of autophagic vesicles are still not completely understood. However, the class IIIphosphatidylinositol 3-kinase (PI3K)/Vps34 complex and phosphatidylinositol-3-phosphate(PI3P) are of core importance to induction of autophagy. Since PX domain containingproteins are known to bind PI3P and other phosphoinositides and mediate membraneremodeling and trafficking events, we performed an imaging-based siRNA screen targetingPX domain proteins using formation of GFP-LC3 positive autophagosomes as a read-out.The PX-BAR protein SNX18 was found to strongly inhibit autophagosome formation. In linewith this, overexpression of SNX18 increased LC3 lipidation and GFP-LC3 spot formationand we demonstrate that membrane binding of SNX18 is required for efficientautophagosome formation. Moreover, SNX18 colocalizes and interacts with the autophagyassociatedproteins LC3 and TBK1. Our study identified the PX-BAR protein SNX18 to beinvolved in membrane events required for autophagosome formation.
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| 4. |
- Malafronte, Loredana, et al.
(författare)
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Coalescence and agglomeration of individual particles of skim milk during convective drying
- 2016
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Ingår i: Journal of Food Engineering. - : Elsevier. - 0260-8774 .- 1873-5770. ; 175, s. 15-23
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Tidskriftsartikel (refereegranskat)abstract
- This work presents a methodology, which combines experiments and modelling, for investigating the coalescence and agglomeration ability of a product and to support the modelling of product properties during spray drying. Two particles were dried simultaneously and contact tests were performed along the drying time. A validated mathematical model describing the drying kinetics of milk particles was used to predict surface conditions during contact tests. Three major mechanisms were observed, coalescence, stickiness, and non-stickiness, which were related to adhesion and cohesion forces. The simulation model allowed evaluation of the surface Ohnesorge dimensionless number and surface glass transition temperature, which showed to be good parameters for predicting contact mechanisms. The model was also used to predict shell formation in drying particles. Wet and dry shell formation was simulated over the drying time, to improve understanding of observed contact behaviour.
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| 5. |
- Malafronte, Loredana, et al.
(författare)
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Estimation of the effective diffusion coefficient of water in skim milk during single-drop drying
- 2015
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Ingår i: Journal of Food Engineering. - : Elsevier Ltd. - 0260-8774 .- 1873-5770. ; 147:C, s. 111-119
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new approach combining experimental methodology and modelling, developed to evaluate the effective diffusivity of water in skim milk during drying over a full range of water contents and temperatures. This parameter is important to support modelling of spray-drying processes and designing of equipment. The effective diffusion coefficient is evaluated using a combination of nuclear magnetic resonance (NMR) and parameter estimation. NMR is used to determine the temperature dependence and parameter estimation is used to estimate the water concentration dependence of the effective diffusivity of water in skim milk (0.90 on total weight basis) during drying by comparing the experimental data obtained using a suspended-drop method, which allows the recording of weight and temperature changes during drying, with the results of a distributed heat and mass transport model. The results indicate that the free-volume theory best predicts the dependence of the effective diffusion coefficient of water in skim milk. A mathematical correlation of effective diffusivity over a full range of water contents and temperatures (from 50 to 90 °C) was obtained and experimentally successfully validated for concentrated skim milk (0.70 on total weight basis).
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| 6. |
- Nordström, Fredrik, et al.
(författare)
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Analysis of solution nonideality of a pseudomorphic drug system through a comprehensive thermodynamic framework for the design of a crystallization process
- 2004
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Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0022-3549 .- 1520-6017. ; 93:4, s. 995-1004
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Tidskriftsartikel (refereegranskat)abstract
- Solutions of a semipolar drug belonging to the alpha(v) beta(iii) integrin antagonist class of compounds were studied in a comprehensive thermodynamic framework. The solubility of two pseudomorphic forms (an anhydrate and a monohydrate) was measured at several temperatures and various solvent mixtures of acetonitrile and water. Both forms displayed a bell-shaped solubility behavior as a function of cosolvent composition. Thermodynamic framework used to analyze the data comprised van't Hoff and enthalpy-entropy compensation analyses. The two pseudomorphs exhibited linear temperature dependence from 25 to 65degreesC at all solvent compositions (i.e., ideal behavior with temperature for fixed solvent composition). Plots of enthalpy of solublization and Gibbs free energy showed two distinct regions with contrasting thermodynamic, and consequently, underlying structural properties (indicating non-deal behavior with solvent composition for a fixed temperature). Solubility increased due to entropy effects in the acetonitrile rich region, whereas enthalpy effects dominated solublization in the water-rich region. Quantification of this phenomenon by plotting DeltaH versus DeltaG showed considerable nonlinearity, and that the two regions were separated by a significant discontinuity-a trend rarely seen before in the literature. The reason behind this behavior is believed to be due to the complex interactions in the solution of the drug in water acetonitrile solvent system. A very significant aspect of the comprehensive thermodynamic analysis is that it helped explain the puzzling feature of the data, which showed that the free energy of phase transformation between the two pseudomorphic forms for a given temperature was not independent of the solvent composition. The resulting explanation has major consequences for crystallization process development.
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| 7. |
- Nordström, Fredrik, et al.
(författare)
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Determination of the activity of a molecular solute in saturated solution
- 2008
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 40:12, s. 1684-1692
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Tidskriftsartikel (refereegranskat)abstract
- Prediction of the solubility of a solid molecular compound in a solvent, as well as, estimation of the solution activity coefficient from experimental solubility data both require estimation of the activity of the solute in the saturated solution. The activity of the solute in the saturated Solution is often defined using the pure melt at the same temperature as the thermodynamic reference. In chemical engineering literature also the activity of the solid is usually defined on the same reference state. However, far below the melting temperature, the properties of this reference state cannot be determined experimentally, and different simplifications and approximations are normally adopted. In the present work, a novel method is presented to determine the activity of the solute in the saturated solution (=ideal solubility) and the heat capacity difference between the pure supercooled melt and solid. The approach is based on rigorous thermodynamics, using standard experimental thermodynamic data at the melting temperature of the pure compound and solubility measurements in different solvents at various temperatures. The method is illustrated using data for ortho-, meta, and para-hydroxybenzoic acid, salicylamide and paracetamol. The results show that complete neglect of the heat capacity terms may lead to estimations of the activity that are incorrect by a factor of 12. Other commonly used simplifications may lead to estimations that are only one-third of the correct value.
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| 8. |
- Nordström, Fredrik, et al.
(författare)
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Determination of the Activity of the Solid phase of Molecular Compounds
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The activity of the solid phase of an organic molecular compound is often defined using the melt at the same temperature as the thermodynamic reference. However, far below the melting temperature, the properties of this reference state cannot be determined experimentally, and different simplifications and approximations are normally adopted. In the present work, a novel method is presented to determine the activity of the solid phase (= ideal solubility) and the heat capacity difference between the supercooled melt and solid. The approach is based on rigorous thermodynamics, using standard experimental thermodynamic data at the melting temperature of the pure compound and solubility measurements in different solvents at various temperatures. The method is illustrated using data for ortho-, meta-, and para-hydroxybenzoic acid, salicylamide and paracetamol. The results show that complete neglect of the heat capacity terms may lead to estimations of the activity that are incorrect by a factor of 12. Other commonly used simplifications may lead to estimations that are only one third of the correct value.
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| 9. |
- Nordström, Fredrik L, et al.
(författare)
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Influence of Solution Thermal and Structural History on the Nucleation of m-Hydroxybenzoic Acid Polymorphs
- 2012
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 12:9, s. 4340-4348
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Tidskriftsartikel (refereegranskat)abstract
- The influence of solution pretreatment on primary nucleation of m-hydroxybenzoic acid has been investigated through 550 cooling crystallization experiments. The metastable zone width has been determined at constant cooling rate, and the time and temperature of the preceding superheating step have been varied. m-Hydroxybenzoic acid has two polymorphs, and the influence of the polymorph used to prepare the solutions has also been investigated. There is an overall tendency in the experiments for the solution to exhibit a larger metastable zone width if it is superheated for a longer time and at a higher temperature, but under the investigated conditions this tendency is not very strong. The results show that the metastable form II preferentially crystallizes in all experiments and in particular when the solution has been more strongly superheated for several hours. However, when the time and/or the temperature of superheating is reduced, there is an increasing tendency to obtain the stable form I. This is most clearly found for solutions prepared by dissolving form I. When the solutions are prepared by dissolution of form II, this tendency is weaker in what appears to be a systematic way. It is hypothesized that, unless the solution is strongly superheated for several hours, it will contain for a significant period of time clusters of solute molecules that can retain some degree of structure from the dissolved crystal. This leads to "memory" effects in the solution, which may influence subsequent nucleation. The work includes a comprehensive review of previous published work on the influence of thermal history on nucleation in solutions and melts.
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| 10. |
- Nordström, Fredrik L., et al.
(författare)
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Primary nucleation of salicylamide : the influence of process conditions and solvent on the metastable zone width
- 2013
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Ingår i: CrystEngComm. - : Royal Society of Chemistry. - 1466-8033. ; 15:36, s. 7285-7297
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Tidskriftsartikel (refereegranskat)abstract
- The onset of nucleation of salicylamide in organic solvents has been measured for a total of 2911 nucleation experiments at a constant cooling rate. The experiments are divided into series of different experimental conditions and for each series, the mean values and distributions of the nucleation events have been recorded. Generally, a significant spread in the onset of nucleation among identical repeated experiments was observed. The solvent and the cooling rate were found to be the factors exerting the greatest influence on the onset of nucleation, whereas the expected effects of the solution volume and the saturation temperature were largely absent. A correlation is observed between the supersaturation ratio at the average onset of nucleation and a group of parameters extracted from the pre-exponential factor in the classical nucleation rate equation, which is in agreement with the concept that a higher attachment frequency facilitates nucleation. It is also found that there can be a profound difference in the metastable zone width between experiments in open and closed crystallizers.
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