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Stading, M., Waqas, M. Q., Holmberg, F., Wiklund, J., Kotze, R. & Ekberg, O. (2019). A Device that Models Human Swallowing. Dysphagia (New York. Print)
Open this publication in new window or tab >>A Device that Models Human Swallowing
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2019 (English)In: Dysphagia (New York. Print), ISSN 0179-051X, E-ISSN 1432-0460Article in journal (Refereed) Epub ahead of print
Abstract [en]

The pharynx is critical for correct swallowing, facilitating the transport of both air and food transport in a highly coordinated manner, and aberrant co-ordination causes swallowing disorders (dysphagia). In this work, an in vitro model of swallowing was designed to investigate the role of rheology in swallowing and for use as a pre-clinical tool for simulation of different routes to dysphagia. The model is based on the geometry of the human pharynx. Manometry is used for pressure measurements and ultrasonic analysis is performed to analyze the flow profiles and determine shear rate in the bolus, the latter being vital information largely missing in literature. In the fully automated model, bolus injection, epiglottis/nasopharynx movement, and ultrasound transducer positioning can be controlled. Simulation of closing of the airways and nasal cavity is modulated by the software, as is a clamping valve that simulates the upper esophageal sphincter. The actions can be timed and valves opened to different degrees, resembling pathologic swallowing conditions. To validate measurements of the velocity profile and manometry, continuous and bolus flow was performed. The respective velocity profiles demonstrated the accuracy and validity of the flow characterization necessary for determining bolus flow. A maximum bolus shear rate of 80 s−1 was noted for syrup-consistency fluids. Similarly, the manometry data acquired compared very well with clinical studies. © 2019, The Author(s).

Keywords
Deglutition, Deglutition disorders, In vitro, Manometry, Pharynx, Rheology, Shear rate
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-37754 (URN)10.1007/s00455-018-09969-2 (DOI)2-s2.0-85060660119 (Scopus ID)
Available from: 2019-02-11 Created: 2019-02-11 Last updated: 2019-02-11Bibliographically approved
Qazi, W., Ekberg, O., Wiklund, J., Kotze, R. & Stading, M. (2019). Assessment of the Food-Swallowing Process Using Bolus Visualisation and Manometry Simultaneously in a Device that Models Human Swallowing. Dysphagia (New York. Print)
Open this publication in new window or tab >>Assessment of the Food-Swallowing Process Using Bolus Visualisation and Manometry Simultaneously in a Device that Models Human Swallowing
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2019 (English)In: Dysphagia (New York. Print), ISSN 0179-051X, E-ISSN 1432-0460Article in journal (Refereed) Epub ahead of print
Abstract [en]

The characteristics of the flows of boluses with different consistencies, i.e. different rheological properties, through the pharynx have not been fully elucidated. The results obtained using a novel in vitro device, the Gothenburg Throat, which allows simultaneous bolus flow visualisation and manometry assessments in the pharynx geometry, are presented, to explain the dependence of bolus flow on bolus consistency. Four different bolus consistencies of a commercial food thickener, 0.5, 1, 1.5 and 2 Pa s (at a shear rate of 50 s −1 )—corresponding to a range from low honey-thick to pudding-thick consistencies on the National Dysphagia Diet (NDD) scale—were examined in the in vitro pharynx. The bolus velocities recorded in the simulator pharynx were in the range of 0.046–0.48 m/s, which is within the range reported in clinical studies. The corresponding wall shear rates associated with these velocities ranged from 13 s −1 (pudding consistency) to 209 s −1 (honey-thick consistency). The results of the in vitro manometry tests using different consistencies and bolus volumes were rather similar to those obtained in clinical studies. The in vitro device used in this study appears to be a valuable tool for pre-clinical analyses of thickened fluids. Furthermore, the results show that it is desirable to consider a broad range of shear rates when assessing the suitability of a certain consistency for swallowing. © 2019, The Author(s).

Keywords
Bolus manometry, Deglutition and deglutition disorders, Rheology, Shear rate, Ultrasound velocimetry
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-38233 (URN)10.1007/s00455-019-09995-8 (DOI)2-s2.0-85062735394 (Scopus ID)
Available from: 2019-03-27 Created: 2019-03-27 Last updated: 2019-03-27Bibliographically approved
Berta, M., Koelewijn, I., Öhgren, C. & Stading, M. (2019). Effect of zein protein and hydroxypropyl methylcellulose on the texture of model gluten-free bread. Journal of texture studies
Open this publication in new window or tab >>Effect of zein protein and hydroxypropyl methylcellulose on the texture of model gluten-free bread
2019 (English)In: Journal of texture studies, ISSN 0022-4901, E-ISSN 1745-4603Article in journal (Refereed) Epub ahead of print
Abstract [en]

The influence of zein protein and hydroxypropyl methylcellulose (HPMC) on the texture and volume of gluten-free bread was investigated. The addition of HPMC to starch affected the dough viscoelasticity and it improved the bread volume during baking since it acts as an emulsifier. The addition of zein protein to gluten-free bread increased the crumb firmness and reduced the crust hardness within the range of concentrations investigated. No zein protein network could be observed in the bread crumb. The zein protein, cold mixed at low concentration, did not enhance the dough elasticity. Due to the lack of a protein network noncovalent interactions may stabilize the bubble structure stabilization within the crumb, rather than covalent links of the protein chain. With an optimized amount of zein protein and HPMC hydrocolloid, the gluten-free bread showed similar texture and staling behavior to that of model wheat bread. The optimized recipe, compiled into a spreadsheet, is available in the supporting information. The microstructural observations suggest that zein could be replaced with another protein for this recipe resulting in a similar bread texture.

Place, publisher, year, edition, pages
Blackwell Publishing Ltd, 2019
Keywords
bread, gluten-free, HPMC, texture, zein, Emulsification, Ions, Proteins, Textures, Bubble structures, Hydroxypropyl methylcellulose, Low concentrations, Micro-structural observations, Non-covalent interaction, Food products
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-38503 (URN)10.1111/jtxs.12394 (DOI)2-s2.0-85064475849 (Scopus ID)
Available from: 2019-05-03 Created: 2019-05-03 Last updated: 2019-05-03Bibliographically approved
Karlsson, K., Larsson, E., Loren, N., Stading, M. & Rigdahl, M. (2019). Extrusion Parameters for Foaming of a β-Glucan Concentrate. Journal of polymers and the environment, 27(6), 1167-1177
Open this publication in new window or tab >>Extrusion Parameters for Foaming of a β-Glucan Concentrate
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2019 (English)In: Journal of polymers and the environment, ISSN 1566-2543, E-ISSN 1572-8919, Vol. 27, no 6, p. 1167-1177Article in journal (Refereed) Published
Abstract [en]

Plastics is a group of materials commonly encountered on a daily basis by many people. They have enabled rapid, low-cost manufacturing of products with complicated geometries and have contributed to the weight reduction of heavy components, especially when produced into a foamed structure. Despite the many advantages of plastics, some drawbacks such as the often fossil-based raw-material and the extensive littering of the material in nature, where it is not degraded for a very long time, needs to be dealt with. One way to address at least one of the issues could be to use polymers from nature instead of fossil-based ones. Here, a β-glucan concentrate originating from barley was investigated. The concentrate was processed into a foam by hot-melt extrusion, and the processing window was established. The effect of different blowing agents was also investigated. Water or a combination of water and sodium bicarbonate were used as blowing agents, the latter apparently giving a more uniform pore structure. The porous structure of the foamed materials was characterized mainly by using a combination of confocal laser scanning microscope and image analysis. The density of the samples was estimated and found to be in a similar range as some polyurethane foams. A set of 3D parameters were also quantified on two selected samples using X-ray microtomography in combination with image analysis, where it was indicated that the porous structure had a pre-determined direction, which followed the direction of the extrusion process. © 2019, The Author(s).

Keywords
Extrusion, Hemicellulose, Image analysis, Starch, X-ray microtomography, Elastomers, Foamed products, Melt spinning, Pore structure, Porosity, Sodium bicarbonate, Tomography, X rays, Complicated geometry, Confocal laser scanning microscope, Extrusion parameter, Hot melt extrusion, Low cost manufacturing, Uniform pore structures, X ray microtomography, Blowing agents
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-38229 (URN)10.1007/s10924-019-01412-3 (DOI)2-s2.0-85062840732 (Scopus ID)
Available from: 2019-03-27 Created: 2019-03-27 Last updated: 2019-06-28Bibliographically approved
Karlsson, K., Nylander, F., Lundman, M., Berta, M., Stading, M., Westman, G. & Rigdahl, M. (2019). Hot-mould foaming of modified hemicelluloses and hydroxypropyl methylcellulose. Journal of polymer research, 26(8)
Open this publication in new window or tab >>Hot-mould foaming of modified hemicelluloses and hydroxypropyl methylcellulose
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2019 (English)In: Journal of polymer research, ISSN 1022-9760, E-ISSN 1572-8935, Vol. 26, no 8Article in journal (Refereed) Published
Abstract [en]

Plastics are a material group which have revolutionized the materials industry during the past century. However, the often fossil origin and littering of the material is problematic. Therefore, this study aims at exploring natural polymers, such as cellulose derivatives and hemicelluloses from different botanical origins, and demonstrate the possibility to use these polymers in a foaming application. The hemicelluloses were chemically treated in order to enhance their performance and foams with ratios as high as 4:1 of hemicellulose and the cellulose derivative, respectively, were successfully produced by a hot-mould foaming technique. The foams were found to be thermally stable up to about 280 °C. The chemical modifications were confirmed by Fourier transform infrared (FTIR) spectra and the foams were evaluated with regard to their liquid absorption capacity as well as their density. After 1 min the best foam absorbed 12.5 g/g of liquid and after 30 min soak time and centrifugation the foams had absorption capacities between 2 and 5 g/g. All foams exhibited densities below 0.1 g/cm3. In both the absorption test and density evaluation, the foams produced from mainly hemicellulose performed in a similar way as the reference foams based only on the cellulose derivative, which is considered an impressive result since cellulose is often reported to have superior properties to hemicelluloses.

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39833 (URN)10.1007/s10965-019-1867-5 (DOI)
Available from: 2019-08-22 Created: 2019-08-22 Last updated: 2019-08-22Bibliographically approved
Qazi, W. & Stading, M. (2019). In vitro models for simulating swallowing. In: Dysphagia: Diagnosis and Treatment (pp. 549-562).
Open this publication in new window or tab >>In vitro models for simulating swallowing
2019 (English)In: Dysphagia: Diagnosis and Treatment, 2019, p. 549-562Chapter in book (Other academic)
Abstract [en]

This chapter gives an overview of the in vitro models that are currently used for studying swallowing. The focus is on the construction, geometry, and performance of mechanical models. Swallowing simulations and mathematical modeling are also considered. The in vitro models that are concerned with the oral, pharyngeal, and esophageal phases of swallowing linked to bolus properties are discussed. The pharyngeal phase is given special consideration, as it is involved in both food transport to the stomach and air transport to the lungs, and therefore constitutes the most critical phase of swallowing.

Keywords
disease simulation, geometry, in vitro study, lung, physical model, stomach, swallowing
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36564 (URN)10.1007/174_2017_116 (DOI)2-s2.0-85052396650 (Scopus ID)
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2018-12-17Bibliographically approved
Sriviriyakul, T., Bogren, S., Schaller, V., Jonasson, C., Blomgren, J., Ahrentorp, F., . . . Johansson, C. (2019). Nanorheological studies of xanthan/water solutions using magnetic nanoparticles. Journal of Magnetism and Magnetic Materials, 473, 268-271
Open this publication in new window or tab >>Nanorheological studies of xanthan/water solutions using magnetic nanoparticles
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2019 (English)In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 473, p. 268-271Article in journal (Refereed) Published
Abstract [en]

We show results of nanorheological studies of different concentrations of xanthan (non-Newtonian fluid) in water using magnetic nanoparticles (MNPs) together with the AC susceptibility (ACS) vs frequency method. For comparison we also show the ACS response for different concentrations of glycerol in water (Newtonian fluid). The ACS response is measured, and the data is modelled using dynamic magnetic models and different viscoelastic models. We study the ACS response (in-phase and out-of-phase ACS components) at different concentrations of xanthan in water (up to 1 wt% xanthan) and with a constant concentration of MNPs. We use MNP systems that show Brownian relaxation (sensitive to changes in the environmental properties around the MNPs). ACS measurements are performed using the DynoMag system. The Brownian relaxation of the MNP system peak is shifting down in frequency and the ACS response is broadening and decreases due to changes in the viscoelastic properties around the MNPs in the xanthan solution. The viscosity and the storage moduli are determined at each excitation frequency and compared with traditional macroscopic small amplitude oscillatory shear rheological measurements. The results from the traditional rheological and nanorheological measurements correlate well at higher xanthan concentration.

Place, publisher, year, edition, pages
Elsevier B.V., 2019
Keywords
AC susceptibility, Brownian relaxation, Glycerol, Magnetic multi-core nanoparticles, Nanorheological measurements, Xanthan, Brownian movement, Digital storage, Magnetic susceptibility, Nanoparticles, Non Newtonian flow, Non Newtonian liquids, Rheology, Viscoelasticity, Ac susceptibility (ACS), Brownian relaxations, Magnetic nano-particles, Magnetic nanoparti cles (MNPs), Multi core, Viscoelastic properties, Nanomagnetics
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-35560 (URN)10.1016/j.jmmm.2018.09.103 (DOI)2-s2.0-85055085870 (Scopus ID)
Note

The authors acknowledge Josefine Mosser for assistance with experimental work. This project receives funding from The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning ( FORMAS ) under grant number 2016-00253 .

Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2019-10-17Bibliographically approved
Karlsson, K., Carrillo Aguilera, M., Karlson, L., Stading, M. & Rigdahl, M. (2018). Chain-Length Shortening of Methyl Ethyl Hydroxyethyl Cellulose: An Evaluation of the Material Properties and Effect on Foaming Ability. Journal of polymers and the environment, 26(11), 4211-4220
Open this publication in new window or tab >>Chain-Length Shortening of Methyl Ethyl Hydroxyethyl Cellulose: An Evaluation of the Material Properties and Effect on Foaming Ability
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2018 (English)In: Journal of polymers and the environment, ISSN 1566-2543, E-ISSN 1572-8919, Vol. 26, no 11, p. 4211-4220Article in journal (Refereed) Published
Abstract [en]

During the past century, plastics have become a natural element in our every-day life. Lately however, an awareness about the fossil origin and often non-degradable nature of many plastics is rising. This has resulted in the emergence of some bio-based and/or biodegradable plastics, often produced from renewable resources. One possible candidate for bioplastics production could be found in cellulose. This paper aims at contributing information regarding a cellulose derivative, which could possibly be used in foamed plastics applications. Therefore, the reduction of the chain-length of a methyl ethyl hydroxyethyl cellulose (MEHEC), assessed by size exclusion chromatography, and the effect of chain-length on the foaming behaviour were studied. The foaming was accomplished with a hot-mould technique using aqueous polymer solutions. The generated steam was here used as the blowing agent and important parameters were polymer concentration and solution viscosity. The density of the produced foams was assessed and was in some cases comparable to that of commodity foams. It was found that reducing the chain-length enabled an increase of the initial polymer concentration for the foaming process. This is believed to be beneficial for creating more structurally stable foams of this type.

Keywords
Cellulose derivatives, Chain-length shortening, Foaming, Methyl ethyl hydroxyethyl cellulose (MEHEC), Rheology, Biodegradable polymers, Blowing agents, Cellulose, Chains, Elastomers, Foamed plastics, Plastics applications, Runway foaming, Size exclusion chromatography, Aqueous polymer solutions, Biodegradable plastics, Bioplastics production, Hydroxyethyl cellulose, Natural elements, Polymer concentrations, Renewable resource, Solution viscosity, Chain length
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-35595 (URN)10.1007/s10924-018-1290-8 (DOI)2-s2.0-85051843231 (Scopus ID)
Note

; Funding details: VR, Vetenskapsrådet; Funding text: Acknowledgements The funding from the Swedish Research Council

Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-06Bibliographically approved
Karlsson, K., Berta, M., Öhgren, C., Stading, M. & Rigdahl, M. (2018). Flow Behaviour and Microstructure of a β-Glucan Concentrate. Journal of polymers and the environment, 26(8), 3352-3361
Open this publication in new window or tab >>Flow Behaviour and Microstructure of a β-Glucan Concentrate
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2018 (English)In: Journal of polymers and the environment, ISSN 1566-2543, E-ISSN 1572-8919, Vol. 26, no 8, p. 3352-3361Article in journal (Refereed) Published
Abstract [en]

The extensional viscosity is an important rheological characteristic of polymer melts. It is however not as frequently reported on as the shear viscosity. The extensional viscosity is of special interest when considering polymeric materials for foaming and film blowing processes. Here, the extensional (and shear) viscosity along with the melt strength and the tensile properties of the corresponding solid film of a β-glucan concentrate are reported on. A capillary viscometer equipped with a hyperbolic die, yielding a contraction flow, was used to assess the extensional viscosity of the aqueous β-glucan compound at room temperature and at elevated temperatures (110 and 130 °C). In general, the extensional viscosity as well as the shear viscosity decreased with increasing deformation rate. The influence of two different amounts of added water (40 and 50%) was also examined. As expected, both types of viscosities decreased with increasing temperature. It is suggested that gelatinization of the starch fraction in the concentrate at 110 and 130 °C contributes to temperature dependence of the viscosity. To some extent, this is supported by light microscopy and confocal scanning laser microscopy studies of the microstructure of the materials. The results reported here indicate that the β-glucan concentrate might, after some modifications, be used as a complement to fossil-based polymers and processed by conventional manufacturing techniques. 

Keywords
Extensional viscosity, Hemicellulose, Mechanical properties, Rheology, Starch, Gelation, Polymer melts, Shear viscosity, Temperature distribution, Capillary viscometers, Confocal scanning laser microscopy, Conventional manufacturing, Increasing temperatures, Rheological characteristics, Temperature dependence, Microstructure
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33509 (URN)10.1007/s10924-018-1207-6 (DOI)2-s2.0-85043363659 (Scopus ID)
Available from: 2018-03-23 Created: 2018-03-23 Last updated: 2018-12-12Bibliographically approved
Moore, H. A., Marucci, M., Härdelin, L., Hjärtstam, J., Stading, M., von Corswant, C. & Larsson, A. (2018). New insights on the influence of manufacturing conditions and molecular weight on phase-separated films intended for controlled release. International Journal of Pharmaceutics, 536(1), 261-271
Open this publication in new window or tab >>New insights on the influence of manufacturing conditions and molecular weight on phase-separated films intended for controlled release
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2018 (English)In: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 536, no 1, p. 261-271Article in journal (Refereed) Published
Abstract [en]

The aim of this work was to investigate how manufacturing conditions influence phase-separated films of ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) with different molecular weights of HPC. Two HPC grades, SSL and M, with weight average molecular weights (Mw) of 30 × 103 g/mol and 365 × 103 g/mol, respectively, were combined with EC 10 cps (70:30 w/w EC/HPC) and spray-coated from ethanol solutions onto a rotating drum under well-controlled process conditions. Generally, a low spray rate resulted in a more rapid film drying process and, consequently, in smaller HPC-rich domains in the phase-separated film structure. For EC/HPC films with the low Mw HPC (SSL) the most rapid drying process resulted in a shift from a HPC-discontinuous to a partly bicontinuous structure and an increase in the permeability for water. In contrast, films containing the high Mw HPC (M) all showed bicontinuous structures, which resulted in overall higher water permeabilities and polymer release compared to the low Mw films. Interestingly, a maximum in permeability was observed for the high Mw films at intermediate spray rates. Below this spray rate the permeability decreased due to a lower amount of polymer released and at higher spray rates, the permeability decreased due to a loss of pore connectivity (or increased tortuosity). To conclude, this study shows that different Mw systems of EC/HPC can respond differently to variations in manufacturing conditions.

Keywords
Controlled release, Ethyl cellulose, Film coating, Hydroxypropyl cellulose, Manufacturing conditions, Molecular weight, Phase separation, Polymer blend, alcohol, hydroxypropylcellulose, polymer, water, Article, chemical structure, controlled drug release, controlled study, priority journal, water permeability
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33245 (URN)10.1016/j.ijpharm.2017.10.012 (DOI)2-s2.0-85035785089 (Scopus ID)
Note

 Funding text: This work was part of the VINN Excellence Centre SuMo Biomaterials.

Available from: 2018-02-13 Created: 2018-02-13 Last updated: 2018-08-20Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0310-4465

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