| 1. |
- Carmona, Pierre, 1995, et al.
(author)
-
Controlling the structure of spin-coated multilayer ethylcellulose/ hydroxypropylcellulose films for drug release
- 2023
-
In: International Journal of Pharmaceutics. - 0378-5173 .- 1873-3476. ; 644
-
Journal article (peer-reviewed)abstract
- Porous phase-separated ethylcellulose/hydroxypropylcellulose (EC/HPC) films are used to control drug transport out of pharmaceutical pellets. Water-soluble HPC leaches out and forms a porous structure that controls the drug transport. Industrially, the pellets are coated using a fluidized bed spraying device, and a layered film exhibiting varying porosity and structure after leaching is obtained. A detailed understanding of the formation of the multilayered, phase-separated structure during production is lacking. Here, we have investigated multilayered EC/HPC films produced by sequential spin-coating, which was used to mimic the industrial process. The effects of EC/HPC ratio and spin speed on the multilayer film formation and structure were investigated using advanced microscopy techniques and image analysis. Cahn-Hilliard simulations were performed to analyze the mixing behavior. A gradient with larger structures close to the substrate surface and smaller structures close to the air surface was formed due to coarsening of the layers already coated during successive deposition cycles. The porosity of the multilayer film was found to vary with both EC/HPC ratio and spin speed. Simulation of the mixing behavior and in situ characterization of the structure evolution showed that the origin of the discontinuities and multilayer structure can be explained by the non-mixing of the layers.
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| 2. |
- Carmona, Pierre, 1995, et al.
(author)
-
Cross-sectional structure evolution of phase-separated spin-coated ethylcellulose/hydroxypropylcellulose films during solvent quenching
- 2022
-
In: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 12:40, s. 26078-26089
-
Journal article (peer-reviewed)abstract
- Porous phase-separated ethylcellulose/hydroxypropylcellulose (EC/HPC) films are used to control drug transport out of pharmaceutical pellets. The films are applied on the pellets using fluidized bed spraying. The drug transport rate is determined by the structure of the porous films that are formed as the water-soluble HPC leaches out. However, a detailed understanding of the evolution of the phase-separated structure during production is lacking. Here, we have investigated EC/HPC films produced by spin-coating, which mimics the industrial manufacturing process. This work aimed to understand the structure formation and film shrinkage during solvent evaporation. The cross-sectional structure evolution was characterized using confocal laser scanning microscopy (CLSM), profilometry and image analysis. The effect of the EC/HPC ratio on the cross-sectional structure evolution was investigated. During shrinkage of the film, the phase-separated structure undergoes a transition from 3D to nearly 2D structure evolution along the surface. This transition appears when the typical length scale of the phase-separated structure is on the order of the thickness of the film. This was particularly pronounced for the bicontinuous systems. The shrinkage rate was found to be independent of the EC/HPC ratio, while the initial and final film thickness increased with increasing HPC fraction. A new method to estimate part of the binodal curve in the ternary phase diagram for EC/HPC in ethanol has been developed. The findings of this work provide a good understanding of the mechanisms responsible for the morphology development and allow tailoring of thin EC/HPC films structure for controlled drug release.
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| 3. |
- Carmona, Pierre, 1995, et al.
(author)
-
Structure evolution during phase separation in spin-coated ethylcellulose/hydroxypropylcellulose films
- 2021
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In: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 17:14, s. 3913-3922
-
Journal article (peer-reviewed)abstract
- Porous phase-separated films made of ethylcellulose (EC) and hydroxypropylcellulose (HPC) are commonly used for controlled drug release. The structure of these thin films is controlling the drug transport from the core to the surrounding liquids in the stomach or intestine. However, detailed understanding of the time evolution of these porous structures as they are formed remains elusive. In this work, spin-coating, a widely applied technique for making thin uniform polymer films, was used to mimic the industrial manufacturing process. The focus of this work was on understanding the structure evolution of phase-separated spin-coated EC/HPC films. The structure evolution was determined using confocal laser scanning microscopy (CLSM) and image analysis. In particular, we determined the influence of spin-coating parameters and EC : HPC ratio on the final phase-separated structure and the film thickness. The film thickness was determined by profilometry and it influences the ethanol solvent evaporation rate and thereby the phase separation kinetics. The spin speed was varied between 1000 and 10 000 rpm and the ratio of EC : HPC in the polymer blend was varied between 78 : 22 wt% and 40 : 60 wt%. The obtained CLSM micrographs showed phase separated structures, typical for the spinodal decomposition phase separation mechanism. By using confocal laser scanning microscopy combined with Fourier image analysis, we could extract the characteristic length scale of the phase-separated final structure. Varying spin speed and EC : HPC ratio gave us precise control over the characteristic length scale and the thickness of the film. The results showed that the characteristic length scale increases with decreasing spin speed and with increasing HPC ratio. The thickness of the spin-coated film decreases with increasing spin speed. It was found that the relation between film thickness and spin speed followed the Meyerhofer equation with an exponent close to 0.5. Furthermore, good correlations between thickness and spin speed were found for the compositions 22 wt% HPC, 30 wt% HPC and 45 wt% HPC. These findings give a good basis for understanding the mechanisms responsible for the morphology development and increase the possibilities to tailor thin EC/HPC film structures.
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| 4. |
- Carmona, Pierre, 1995, et al.
(author)
-
Structure formation and coarsening kinetics of phase-separated spin-coated ethylcellulose/hydroxypropylcellulose films
- 2022
-
In: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 18:16, s. 3206-3217
-
Journal article (peer-reviewed)abstract
- Porous phase-separated ethylcellulose/hydroxypropylcellulose (EC/HPC) films are used to control drug transport from pharmaceutical pellets. The drug transport rate is determined by the structure of the porous films that are formed as water-soluble HPC leaches out. However, a detailed understanding of the evolution of the phase-separated structure in the films is lacking. In this work, we have investigated EC/HPC films produced by spin-coating, mimicking the industrial fluidized bed spraying. The aim was to investigate film structure evolution and coarsening kinetics during solvent evaporation. The structure evolution was characterized using confocal laser scanning microscopy and image analysis. The effect of the EC:HPC ratio (15 to 85 wt% HPC) on the structure evolution was determined. Bicontinuous structures were found for 30 to 40 wt% HPC. The growth of the characteristic length scale followed a power law, L(t) ∼ t(n), with n ∼ 1 for bicontinuous structures, and n ∼ 0.45-0.75 for discontinuous structures. The characteristic length scale after kinetic trapping ranged between 3.0 and 6.0 μm for bicontinuous and between 0.6 and 1.6 μm for discontinuous structures. Two main coarsening mechanisms could be identified: interfacial tension-driven hydrodynamic growth for bicontinuous structures and diffusion-driven coalescence for discontinuous structures. The 2D in-plane interface curvature analysis showed that the mean curvature decreased as a function of time for bicontinuous structures, confirming that interfacial tension is driving the growth. The findings of this work provide a good understanding of the mechanisms responsible for morphology development and open for further tailoring of thin EC/HPC film structures for controlled drug release. © 2022 The Royal Society of Chemistry
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| 5. |
- Eriksson Barman, Sandra, 1985, et al.
(author)
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New characterization measures of pore shape and connectivity applied to coatings used for controlled drug release
- 2021
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In: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 1520-6017 .- 0022-3549. ; 110:7, s. 2753-2764
-
Journal article (peer-reviewed)abstract
- Pore geometry characterization-methods are important tools for understanding how pore structure influences properties such as transport through a porous material. Bottlenecks can have a large influence on transport and related properties. However, existing methods only catch certain types of bottleneck effects caused by variations in pore size. We here introduce a new measure, geodesic channel strength, which captures a different type of bottleneck effect caused by many paths coinciding in the same pore. We further develop new variants of pore size measures and propose a new way of visualizing 3-D characterization results using layered images. The new measures together with existing measures were used to characterize and visualize properties of 3-D FIB-SEM images of three leached ethyl-cellulose/hydroxypropyl-cellulose films. All films were shown to be anisotropic, and the strongest anisotropy was found in the film with lowest porosity. This film had very tortuous paths and strong geodesic channel-bottlenecks, while the paths through the other two films were relatively straight with well-connected pore networks. The geodesic channel strength was shown to give important new visual and quantitative insights about connectivity, and the new pore size measures provided useful information about anisotropies and inhomogeneities in the pore structures. The methods have been implemented in the freely available software MIST.
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| 6. |
- Fager, Cecilia, 1990, et al.
(author)
-
3D high spatial resolution visualisation and quantification of interconnectivity in polymer films
- 2020
-
In: International Journal of Pharmaceutics. - : Elsevier B.V.. - 0378-5173 .- 1873-3476. ; 587
-
Journal article (peer-reviewed)abstract
- A porous network acts as transport paths for drugs through films for controlled drug release. The interconnectivity of the network strongly influences the transport properties. It is therefore important to quantify the interconnectivity and correlate it to transport properties for control and design of new films. This work presents a novel method for 3D visualisation and analysis of interconnectivity. High spatial resolution 3D data on porous polymer films for controlled drug release has been acquired using a focused ion beam (FIB) combined with a scanning electron microscope (SEM). The data analysis method enables visualisation of pore paths starting at a chosen inlet pore, dividing them into groups by length, enabling a more detailed quantification and visualisation. The method also enables identification of central features of the porous network by quantification of channels where pore paths coincide. The method was applied to FIB-SEM data of three leached ethyl cellulose (EC)/hydroxypropyl cellulose (HPC) films with different weight percentages. The results from the analysis were consistent with the experimentally measured release properties of the films. The interconnectivity and porosity increase with increasing amount of HPC. The bottleneck effect was strong in the leached film with lowest porosity.
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| 7. |
- Fager, Cecilia, 1990, et al.
(author)
-
Correlating 3D porous structure in polymer films with mass transport properties using FIB-SEM tomography
- 2021
-
In: Chemical Engineering Science: X. - : Elsevier BV. - 2590-1400. ; 12
-
Journal article (peer-reviewed)abstract
- Porous polymer coatings are used to control drug release from pharmaceutical products. The coating covers a drug core and depending on the porous structure, different drug release rates are obtained. This work presents mass transport simulations performed on porous ethyl cellulose films with different porosities. The simulations were performed on high spatial resolution 3D data obtained using a focused ion beam scanning electron microscope. The effective diffusion coefficient of water was determined using a diffusion chamber. Lattice Boltzmann simulations were used to simulate water diffusion in the 3D data. The simulated coefficient was in good agreement with the measured coefficient. From the results it was concluded that the tortuosity and constrictivity of the porous network increase with decreasing amount of added hydroxypropyl cellulose, resulting in a sharp decrease in effective diffusion. This work shows that high spatial resolution 3D data is necessary, and that 2D data is insufficient, in order to predict diffusion through the porous structure with high accuracy.
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| 8. |
- Fager, Cecilia, 1990, et al.
(author)
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Optimization of FIB-SEM Tomography and Reconstruction for Soft, Porous, and Poorly Conducting Materials
- 2020
-
In: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 26:4, s. 837-845
-
Journal article (peer-reviewed)abstract
- Tomography using a focused ion beam (FIB) combined with a scanning electron microscope (SEM) is well-established for a wide range of conducting materials. However, performing FIB-SEM tomography on ion- and electron-beam-sensitive materials as well as poorly conducting soft materials remains challenging. Some common challenges include cross-sectioning artifacts, shadowing effects, and charging. Fully dense materials provide a planar cross section, whereas pores also expose subsurface areas of the planar cross-section surface. The image intensity of the subsurface areas gives rise to overlap between the grayscale intensity levels of the solid and pore areas, which complicates image processing and segmentation for three-dimensional (3D) reconstruction. To avoid the introduction of artifacts, the goal is to examine porous and poorly conducting soft materials as close as possible to their original state. This work presents a protocol for the optimization of FIB-SEM tomography parameters for porous and poorly conducting soft materials. The protocol reduces cross-sectioning artifacts, charging, and eliminates shadowing effects. In addition, it handles the subsurface and grayscale intensity overlap problems in image segmentation. The protocol was evaluated on porous polymer films which have both poor conductivity and pores. 3D reconstructions, with automated data segmentation, from three films with different porosities were successfully obtained.
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| 9. |
- Loren, Niklas, et al.
(author)
-
Sodium reduction in foods : Challenges and strategies for technical solutions
- 2023
-
In: Journal of Food Science. - : John Wiley and Sons Inc. - 0022-1147 .- 1750-3841. ; 88:3, s. 885-
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Journal article (peer-reviewed)abstract
- In many parts of the world, sodium consumption is higher than recommended levels, representing one of the most important food-related health challenges and leading to considerable economical costs for society. Therefore, there is a need to find technical solutions for sodium reduction that can be implemented by food producers and within food services. The aims of this review are to discuss the barriers related to sodium reduction and to highlight a variety of technical solutions. The barriers relate to consumer perception, microbiology, processing, and physicochemistry. Existing technical solutions include inhomogeneous salt distribution, coated salt particles, changing particle sizes and forms, surface coating, multisensory combinations, sodium replacements, double emulsions, adapted serum release by microstructure design, and adapted brittleness by microstructure design. These solutions, their implementation and the associated challenges, and applicable product categories are described. Some of these solutions are ready for use or are in their early development stages. Many solutions are promising, but in most cases, some form of adaptation or optimization is needed before application in specific products, and care must always be taken to ensure food safety. For instance, further research and innovation are required in the dynamic evolution of saltiness perception, consumer acceptance, the binding and migration of sodium, juiciness, microbiological safety, and the timing of salt addition during processing. Once implemented, these solutions will undoubtedly support food producers and food services in reducing sodium content and extend the application of the solutions to different foods. © 2022 Research Institutes of Sweden, Swedish Food Federation and Lyckeby Culinar AB.
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| 10. |
- Niimi, Jun, et al.
(author)
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Saltiness enhancement : Impact of acid added to bread with heterogeneously distributed sodium chloride
- 2023
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In: Lebensmittel-Wissenschaft + Technologie. - : Academic Press. - 0023-6438 .- 1096-1127. ; 176
-
Journal article (peer-reviewed)abstract
- The current global sodium consumption exceeds recommended daily intakes and there is a great need to reduce the sodium content in foods for a healthier society. The current study investigated the effect of combining sensory interaction principles and heterogeneous distribution of NaCl in bread on sensory properties, structure, and NaCl distribution. Breads were prepared in three different arrangements of NaCl distribution: homogenous, layered, and layered with lactic acid. Within each arrangement, four NaCl levels were tested. The breads were evaluated by a sensory panel for perceived saltiness, sourness, and qualitative texture, measured for stiffness, and the NaCl distribution was determined by X-ray fluorescence microscopy (XFM). Perceived saltiness was significantly enhanced in breads beyond heterogeneous NaCl distribution when lactic acid was added. Stiffness measurements were affected by layering of bread, the layers without NaCl were stiffer with an increase in overall salt concentration. The heterogeneous distribution of NaCl in layered breads could be visualised by XFM and textural consequences of layering bread are discussed. The current study demonstrates the potential of combining principles of pulsation of taste and sensory interactions together to enhance salt perception, and hence suggesting the approach as a possible further strategy for NaCl reduction in bread.
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| 11. |
- Ohgren, C., et al.
(author)
-
Chapter 12: Food Structure Analysis Using Light and Confocal Microscopy
- 2020
-
In: Food Chemistry, Function and Analysis. - : The Royal Society of Chemistry. - 2398-0664 .- 2398-0656. ; 2020-January, s. 287-308
-
Book chapter (other academic/artistic)abstract
- Microstructure codes for the properties of food. Processing enables the microstructure. Food microstructures are in most cases hierarchical, heterogeneous, multiphase, and complex. A full understanding of the food microstructure requires the characterization at many different length scales. Light microscopy and confocal laser scanning microscopy are powerful tools to image food microstructures at the micrometer level. In this chapter, the principles and use of these microscopy techniques are described. Examples of the use of light microscopy and confocal laser scanning microscopy to characterize and understand the microstructures in bread and dough, fibrous vegetable protein structures, plant cell walls, fat-rich food, and mayonnaise are discussed. In the end, an outlook on the use of light microscopy and confocal laser scanning microscopy in foods is given.
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| 12. |
- Röding, Magnus, et al.
(author)
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Inverse design of anisotropic spinodoid materials with prescribed diffusivity
- 2022
-
In: Scientific Reports. - : Nature Research. - 2045-2322. ; 12:1
-
Journal article (peer-reviewed)abstract
- The three-dimensional microstructure of functional materials determines its effective properties, like the mass transport properties of a porous material. Hence, it is desirable to be able to tune the properties by tuning the microstructure accordingly. In this work, we study a class of spinodoid i.e. spinodal decomposition-like structures with tunable anisotropy, based on Gaussian random fields. These are realistic yet computationally efficient models for bicontinuous porous materials. We use a convolutional neural network for predicting effective diffusivity in all three directions. We demonstrate that by incorporating the predictions of the neural network in an approximate Bayesian computation framework for inverse problems, we can in a computationally efficient manner design microstructures with prescribed diffusivity in all three directions. © 2022, The Author(s).
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| 13. |
- Röding, Magnus, 1984, et al.
(author)
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Three-dimensional reconstruction of porous polymer films from FIB-SEM nanotomography data using random forests
- 2021
-
In: Journal of Microscopy. - : Wiley. - 1365-2818 .- 0022-2720. ; 281:1, s. 76-86
-
Journal article (peer-reviewed)abstract
- Combined focused ion beam and scanning electron microscope (FIB-SEM) tomography is a well-established technique for high resolution imaging and reconstruction of the microstructure of a wide range of materials. Segmentation of FIB-SEM data is complicated due to a number of factors; the most prominent is that for porous materials, the scanning electron microscope image slices contain information not only from the planar cross-section of the material but also from underlying, exposed subsurface pores. In this work, we develop a segmentation method for FIB-SEM data from ethyl cellulose porous films made from ethyl cellulose and hydroxypropyl cellulose (EC/HPC) polymer blends. These materials are used for coating pharmaceutical oral dosage forms (tablets or pellets) to control drug release. We study three samples of ethyl cellulose and hydroxypropyl cellulose with different volume fractions where the hydroxypropyl cellulose phase has been leached out, resulting in a porous material. The data are segmented using scale-space features and a random forest classifier. We demonstrate good agreement with manual segmentations. The method enables quantitative characterization and subsequent optimization of material structure for controlled release applications. Although the methodology is demonstrated on porous polymer films, it is applicable to other soft porous materials imaged by FIB-SEM. We make the data and software used publicly available to facilitate further development of FIB-SEM segmentation methods. Lay Description For imaging of very fine structures in materials, the resolution limits of, e.g. X-ray computed tomography quickly become a bottleneck. Scanning electron microscopy (SEM) provides a way out, but it is essentially a two-dimensional imaging technique. One manner in which to extend it to three dimensions is to use a focused ion beam (FIB) combined with a scanning electron microscopy and acquire tomography data. In FIB-SEM tomography, ions are used to perform serial sectioning and the electron beam is used to image the cross section surface. This is a well-established method for a wide range of materials. However, image analysis of FIB-SEM data is complicated for a variety of reasons, in particular for porous media. In this work, we analyse FIB-SEM data from ethyl cellulose porous films made from ethyl cellulose and hydroxypropyl cellulose (EC/HPC) polymer blends. These films are used as coatings for controlled drug release. The aim is to perform image segmentation, i.e. to identify which parts of the image data constitute the pores and the solid, respectively. Manual segmentation, i.e. when a trained operator manually identifies areas constituting pores and solid, is too time-consuming to do in full for our very large data sets. However, by performing manual segmentation on a set of small, random regions of the data, we can train a machine learning algorithm to perform automatic segmentation on the entire data sets. The method yields good agreement with the manual segmentations and yields porosities of the entire data sets in very good agreement with expected values. The method facilitates understanding and quantitative characterization of the geometrical structure of the materials, and ultimately understanding of how to tailor the drug release.
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| 14. |
- Schott, Florian, et al.
(author)
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Structural formation during bread baking in a combined microwave-convective oven determined by sub-second in-situ synchrotron X-ray microtomography
- 2023
-
In: Food Research International. - : Elsevier Ltd. - 0963-9969 .- 1873-7145. ; 173
-
Journal article (peer-reviewed)abstract
- A new concept has been developed for characterizing the real-time evolution of the three-dimensional pore and lamella microstructure of bread during baking using synchrotron X-ray microtomography (SRµCT). A commercial, combined microwave-convective oven was modified and installed at the TOMCAT synchrotron tomography beamline at the Swiss Light Source (SLS), to capture the 3D dough-to-bread structural development in-situ at the micrometer scale with an acquisition time of 400 ms. This allowed characterization and quantitative comparison of three baking technologies: (1) convective heating, (2) microwave heating, and (3) a combination of convective and microwave heating. A workflow for automatic batchwise image processing and analysis of 3D bread structures (1530 analyzed volumes in total) was established for porosity, individual pore volume, elongation, coordination number and local wall thickness, which allowed for evaluation of the impact of baking technology on the bread structure evolution. The results showed that the porosity, mean pore volume and mean coordination number increase with time and that the mean local cell wall thickness decreases with time. Small and more isolated pores are connecting with larger and already more connected pores as function of time. Clear dependencies are established during the whole baking process between the mean pore volume and porosity, and between the mean local wall thickness and the mean coordination number. This technique opens new opportunities for understanding the mechanisms governing the structural changes during baking and discern the parameters controlling the final bread quality. © 2023 The Author(s)
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| 15. |
- Skarstrom, V. W., et al.
(author)
-
DeepFRAP: Fast fluorescence recovery after photobleaching data analysis using deep neural networks
- 2021
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In: Journal of Microscopy. - : Wiley. - 0022-2720 .- 1365-2818. ; 282:2, s. 146-161
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Journal article (peer-reviewed)abstract
- Conventional analysis of fluorescence recovery after photobleaching (FRAP) data for diffusion coefficient estimation typically involves fitting an analytical or numerical FRAP model to the recovery curve data using non-linear least squares. Depending on the model, this can be time consuming, especially for batch analysis of large numbers of data sets and if multiple initial guesses for the parameter vector are used to ensure convergence. In this work, we develop a completely new approach, DeepFRAP, utilizing machine learning for parameter estimation in FRAP. From a numerical FRAP model developed in previous work, we generate a very large set of simulated recovery curve data with realistic noise levels. The data are used for training different deep neural network regression models for prediction of several parameters, most importantly the diffusion coefficient. The neural networks are extremely fast and can estimate the parameters orders of magnitude faster than least squares. The performance of the neural network estimation framework is compared to conventional least squares estimation on simulated data, and found to be strikingly similar. Also, a simple experimental validation is performed, demonstrating excellent agreement between the two methods. We make the data and code used publicly available to facilitate further development of machine learning-based estimation in FRAP.
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| 16. |
- Skärberg, F., et al.
(author)
-
Convolutional neural networks for segmentation of FIB-SEM nanotomography data from porous polymer films for controlled drug release
- 2021
-
In: Journal of Microscopy. - : John Wiley and Sons Inc. - 0022-2720 .- 1365-2818. ; 283:1, s. 51-63
-
Journal article (peer-reviewed)abstract
- Phase-separated polymer films are commonly used as coatings around pharmaceutical oral dosage forms (tablets or pellets) to facilitate controlled drug release. A typical choice is to use ethyl cellulose and hydroxypropyl cellulose (EC/HPC) polymer blends. When an EC/HPC film is in contact with water, the leaching out of the water-soluble HPC phase produces an EC film with a porous network through which the drug is transported. The drug release can be tailored by controlling the structure of this porous network. Imaging and characterization of such EC porous films facilitates understanding of how to control and tailor film formation and ultimately drug release. Combined focused ion beam and scanning electron microscope (FIB-SEM) tomography is a well-established technique for high-resolution imaging, and suitable for this application. However, for segmenting image data, in this case to correctly identify the porous network, FIB-SEM is a challenging technique to work with. In this work, we implement convolutional neural networks for segmentation of FIB-SEM image data. The data are acquired from three EC porous films where the HPC phases have been leached out. The three data sets have varying porosities in a range of interest for controlled drug release applications. We demonstrate very good agreement with manual segmentations. In particular, we demonstrate an improvement in comparison to previous work on the same data sets that utilized a random forest classifier trained on Gaussian scale-space features. Finally, we facilitate further development of FIB-SEM segmentation methods by making the data and software used open access.
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| 17. |
- Townsend, Philip, 1991, et al.
(author)
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Stochastic modelling of 3D fiber structures imaged with X-ray microtomography
- 2021
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In: Computational materials science. - : Elsevier B.V.. - 0927-0256 .- 1879-0801. ; 194
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Journal article (peer-reviewed)abstract
- Many products incorporate into their design fibrous material with particular levels of permeability as a way to control the retention and flow of liquid. The production and experimental testing of these materials can be expensive and time consuming, particularly if it needs to be optimised to a desired level of absorbency. We consider a parametric virtual fiber model as a replacement for the real material to facilitate studying the relationship between structure and properties in a cheaper and more convenient manner. 3D image data sets of a sample fibrous material are obtained using X-ray microtomography and the individual fibers isolated. The segmented fibers are used to estimate the parameters of a 3D stochastic model for generating softcore virtual fiber structures. We use several spatial measures to show the consistency between the real and virtual structures, and demonstrate with lattice Boltzmann simulations that our virtual structure has good agreement with respect to the permeability of the physical material. © 2021 The Author(s)
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| 18. |
- Townsend, Philip, 1991, et al.
(author)
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Tessellation-based stochastic modelling of 3D coating structures imaged with FIB-SEM tomography
- 2021
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In: Computational Materials Science. - : Elsevier BV. - 0927-0256 .- 1879-0801. ; 197
-
Journal article (peer-reviewed)abstract
- To facilitate printing, coatings are typically applied to paperboard used for packaging to provide a good surface for application. To optimise the performance of the coating, it is important to understand the relationship between the microstructure of the material and its mass transport properties. In this work, three samples of paperboard coating are imaged using combined focused ion beam and scanning electron microscope (FIB-SEM) tomography data appropriately segmented to characterise the internal microstructure. These images are used to inform a parametric, tessellation-based stochastic three-dimensional model intended to mimic the irregular geometry of the particles that can be seen in the coating. Parameters for the model are estimated from the FIBSEM image data, and we demonstrate good agreement between the real and virtual structures both in terms of geometrical measures and mass transport properties. The development of this model facilitates exploration of the relationship between the structure and its properties.
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| 19. |
- Öhgren, Camilla, et al.
(author)
-
Food Structure Analysis Using Light and Confocal Microscopy : Chapter 12
- 2020
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In: Handbook of Food Structure Development. - : Royal Society of Chemistry. - 9781782629221 - 9781788011273 - 9781788011785 - 9781788012164 ; , s. 287-308
-
Book chapter (peer-reviewed)abstract
- Microstructure codes for the properties of food. Processing enables the microstructure. Food microstructures are in most cases hierarchical, heterogeneous, multiphase, and complex. A full understanding of the food microstructure requires the characterization at many different length scales. Light microscopy and confocal laser scanning microscopy are powerful tools to image food microstructures at the micrometer level. In this chapter, the principles and use of these microscopy techniques are described. Examples of the use of light microscopy and confocal laser scanning microscopy to characterize and understand the microstructures in bread and dough, fibrous vegetable protein structures, plant cell walls, fat-rich food, and mayonnaise are discussed. In the end, an outlook on the use of light microscopy and confocal laser scanning microscopy in foods is given..
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