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Gråsjö, Johan
Publications (10 of 24) Show all publications
Edueng, K., Bergström, C., Gråsjö, J. & Mahlin, D. (2019). Long-term physical (in)stability of spray-dried amorphous drugs: relationship with glass-forming ability and physicochemical properties. Pharmaceutics, 11(9), Article ID 425.
Open this publication in new window or tab >>Long-term physical (in)stability of spray-dried amorphous drugs: relationship with glass-forming ability and physicochemical properties
2019 (English)In: Pharmaceutics, ISSN 1999-4923, E-ISSN 1999-4923, Vol. 11, no 9, article id 425Article in journal (Other academic) Published
National Category
Social and Clinical Pharmacy
Research subject
Pharmaceutical Science
Identifiers
urn:nbn:se:uu:diva-390255 (URN)10.3390/pharmaceutics11090425 (DOI)000489151700053 ()31438566 (PubMedID)
Funder
Swedish Research Council, 621-2011-2445Swedish Research Council, 621-2014-3309
Available from: 2019-08-07 Created: 2019-08-07 Last updated: 2019-11-08Bibliographically approved
Chatzigeorgiou, E., Århammar, C., Gråsjö, J., Strömme, M. & Rubensson, J.-E. (2019). Resonant Inelastic X-ray Scattering on Mesoporous Magnesium Carbonate. In: The 40th International Conference on Vacuum Ultraviolet and X-ray Physics: . Paper presented at The 40th International Conference on Vacuum Ultraviolet and X-ray Physics, San Fransisco 2019. San Fransisco
Open this publication in new window or tab >>Resonant Inelastic X-ray Scattering on Mesoporous Magnesium Carbonate
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2019 (English)In: The 40th International Conference on Vacuum Ultraviolet and X-ray Physics, San Fransisco, 2019Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
San Fransisco: , 2019
Series
Boreas. Uppsala Studies in Ancient Mediterranean and Near Eastern Civilizations, ISSN 0346-6442
Series
VUVX
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-389518 (URN)
Conference
The 40th International Conference on Vacuum Ultraviolet and X-ray Physics, San Fransisco 2019
Available from: 2019-07-16 Created: 2019-07-16 Last updated: 2019-07-16
Chatzigeorgiou, E., Århammar, C., Gråsjö, J., Ekholm, V., Såthe, C., Olovsson, W., . . . Rubensson, J.-E. (2019). Soft X-ray Spectroscopy on  amorphous and crystalline magnesium carbonate. In: EUROMAT 2019: . Paper presented at EUROMAT 2019, 1-5 September 2019, Stockholm,. , Article ID 14135.
Open this publication in new window or tab >>Soft X-ray Spectroscopy on  amorphous and crystalline magnesium carbonate
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2019 (English)In: EUROMAT 2019, 2019, article id 14135Conference paper, Oral presentation with published abstract (Refereed)
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-395335 (URN)
Conference
EUROMAT 2019, 1-5 September 2019, Stockholm,
Available from: 2019-10-17 Created: 2019-10-17 Last updated: 2019-10-17
Edueng, K., Mahlin, D., Gråsjö, J., Nylander, O., Thakrani, M. & Bergström, C. (2019). Supersaturation Potential of Amorphous Active Pharmaceutical Ingredients after Long-Term Storage. Molecules, 24(15), Article ID 2731.
Open this publication in new window or tab >>Supersaturation Potential of Amorphous Active Pharmaceutical Ingredients after Long-Term Storage
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2019 (English)In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 24, no 15, article id 2731Article in journal (Refereed) Published
Abstract [en]

This study explores the effect of physical aging and/or crystallization on the supersaturation potential and crystallization kinetics of amorphous active pharmaceutical ingredients (APIs). Spray-dried, fully amorphous indapamide, metolazone, glibenclamide, hydrocortisone, hydrochlorothiazide, ketoconazole, and sulfathiazole were used as model APIs. The parameters used to assess the supersaturation potential and crystallization kinetics were the maximum supersaturation concentration (Cmax,app), the area under the curve (AUC), and the crystallization rate constant (k). These were compared for freshly spray-dried and aged/crystallized samples. Aged samples were stored at 75% relative humidity for 168 days (6 months) or until they were completely crystallized, whichever came first. The solid-state changes were monitored with differential scanning calorimetry, Raman spectroscopy, and powder X-ray diffraction. Supersaturation potential and crystallization kinetics were investigated using a tenfold supersaturation ratio compared to the thermodynamic solubility using the µDISS Profiler. The physically aged indapamide and metolazone and the minimally crystallized glibenclamide and hydrocortisone did not show significant differences in their Cmax,app and AUC when compared to the freshly spray-dried samples. Ketoconazole, with a crystalline content of 23%, reduced its Cmax,app and AUC by 50%, with Cmax,app being the same as the crystalline solubility. The AUC of aged metolazone, one of the two compounds that remained completely amorphous after storage, significantly improved as the crystallization kinetics significantly decreased. Glibenclamide improved the most in its supersaturation potential from amorphization. The study also revealed that, besides solid-state crystallization during storage, crystallization during dissolution and its corresponding pathway may significantly compromise the supersaturation potential of fully amorphous APIs.

Keywords
physical aging, crystallization, amorphous, supersaturation potential, crystallization kinetics, nucleation pathway, crystal growth, dissolution, solvent shift, spray-drying
National Category
Pharmaceutical Sciences
Research subject
Pharmaceutical Science
Identifiers
urn:nbn:se:uu:diva-389887 (URN)10.3390/molecules24152731 (DOI)000482441100054 ()31357587 (PubMedID)
Funder
EU, European Research Council, 63896Swedish Research Council, 621-2014-330Swedish Research Council, 621-2011-2445
Available from: 2019-07-30 Created: 2019-07-30 Last updated: 2019-10-02Bibliographically approved
Pazesh, S., Gråsjö, J., Berggren, J. & Alderborn, G. (2017). Comminution-amorphisation relationships during ball milling of lactose at different milling conditions. International Journal of Pharmaceutics, 528(1-2), 215-227
Open this publication in new window or tab >>Comminution-amorphisation relationships during ball milling of lactose at different milling conditions
2017 (English)In: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 528, no 1-2, p. 215-227Article in journal (Refereed) Published
Abstract [en]

The purpose of the study was to investigate the relationship between comminution and amorphisation of alpha-lactose monohydrate particles during ball milling under different milling conditions, including ball-to-powder mass ratio, milling time and ball diameter. The results revealed that at a constant ball filling ratio, ball-to-powder mass ratio of 25:1 resulted in the lowest minimum particle diameter of similar to 5 mu m and the highest degree of apparent amorphous content of 82%. The rate of comminution was high during early stage of milling whereas the degree of apparent amorphous content increased gradually at a slow rate. An increased ball-to-powder mass ratio during milling increased both the rate of comminution and the rate of amorphisation. Using a given ball-to-powder mass ratio, the ball diameter affected the degree of apparent amorphous content of the particles while the particle diameter remained unchanged. The relationship between comminution and amorphisation could be described as consisting of two stages, i.e. comminution dominated and amorphisation dominated stage. It was proposed that the rate constant of comminution and amorphisation are controlled by stress energy distribution in the milling jar and the stress energy distribution is regulated by the ball motion pattern that can be affected by the process parameter used.

Keywords
Ball milling, process-induced disordering, amorphisation, comminution, comminution rate constant, α-lactose monohydrate, stress energy distribution
National Category
Chemical Sciences
Research subject
Pharmaceutical Science
Identifiers
urn:nbn:se:uu:diva-317797 (URN)10.1016/j.ijpharm.2017.05.043 (DOI)000408007600020 ()28546073 (PubMedID)
Note

Title in dissertation list of articles: "Comminution-amorphisation relationships during ball milling of lactose at different stress energies"

Available from: 2017-03-19 Created: 2017-03-19 Last updated: 2017-11-27Bibliographically approved
Jonsson, H., Gråsjö, J. & Frenning, G. (2017). Mechanical behaviour of ideal elastic-plastic particles subjected to different triaxial loading conditions. Powder Technology, 315, 347-355
Open this publication in new window or tab >>Mechanical behaviour of ideal elastic-plastic particles subjected to different triaxial loading conditions
2017 (English)In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 315, p. 347-355Article in journal (Refereed) Published
Abstract [en]

The contact force development for two types of polymeric elastoplastic particles subjected to different triaxial loading conditions was studied experimentally utilising a unique triaxial testing apparatus. In order to evaluate the experimental results, a finite element analysis was performed. The experimental findings highlighted the importance of contact dependence, which manifested itself in two principally different ways. Firstly, a reduced stiffness was observed when plastic deformation ceased to be fully contained, which, depending on the loading conditions, occurred at an engineering strain of about 5-10%. Secondly, a markedly increased stiffness was observed when particle confinement inhibited further plastic deformation, making elastic volume reduction the predominant deformation mode. The experimental results could be well reproduced by the numerical simulations, provided that isotropic hardening was included in the elastoplastic model. In an attempt to invariantly describe the data, a nominal contact pressure was determined as a function of the volumetric constraint of the particle. This resulted in an adequate collapse of results obtained for different loading conditions onto a single master curve at large volumetric constraint. In summary, this paper should be considered as a step along the pathway towards our long term goal of introducing novel and improved contact models.

Keywords
Particle mechanics, Triaxial, Compression, Spatial confinement, Contact dependence
National Category
Applied Mechanics
Identifiers
urn:nbn:se:uu:diva-323755 (URN)10.1016/j.powtec.2017.04.005 (DOI)000401593600041 ()
Funder
Swedish Research Council, 621-2011-4049
Available from: 2017-06-13 Created: 2017-06-13 Last updated: 2018-04-12Bibliographically approved
Jonsson, H., Gråsjö, J., Nordström, J., Johansson, N. & Frenning, G. (2015). An apparatus for confined triaxial testing of single particles. Powder Technology, 270, 121-127
Open this publication in new window or tab >>An apparatus for confined triaxial testing of single particles
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2015 (English)In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 270, p. 121-127Article in journal (Refereed) Published
Abstract [en]

A novel triaxial apparatus employing overlapping rigid boundaries has been designed and constructed for experimental measurement of contact forces under confined compression of single granules in the mm-scale. The performance of the apparatus was evaluated by performing uniaxial and triaxial compression experiments on ideal elastic-plastic materials. Compression curves were compared with the fully plastic Abbott-Firestone contact model and with results from FEM simulations. The increase in contact force associated with confined conditions was observed in the compression curves from triaxial compression experiments, as supported by predictions from simulations using single particle contact models. Hence, a new method for the assessment of mechanical behaviour of single particles under confined compression can be considered as established.

Keywords
Compression, Triaxial, Single particles, Confined conditions, Apparatus design, Contact mechanics
National Category
Pharmaceutical Sciences
Identifiers
urn:nbn:se:uu:diva-239203 (URN)10.1016/j.powtec.2014.10.016 (DOI)000347579300014 ()
Funder
Swedish Research Council, 621-2011-4049
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2018-04-12Bibliographically approved
Pietzsch, A., Nisar, J., Jamstorp, E., Gråsjö, J., Kennedy, B., Hennies, F., . . . Rubensson, J.-E. (2015). Kaolinite: defect states define material properties-a soft x-ray and first principles study of the band gap. Journal of Electron Spectroscopy and Related Phenomena, 202, 11-15
Open this publication in new window or tab >>Kaolinite: defect states define material properties-a soft x-ray and first principles study of the band gap
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2015 (English)In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 202, p. 11-15Article in journal (Refereed) Published
National Category
Condensed Matter Physics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-179354 (URN)10.1016/j.elspec.2015.02.003 (DOI)000357904600003 ()
Funder
Swedish Research Council
Note

Funding: HEC of Pakistan, Sandvik AB 

Available from: 2012-08-13 Created: 2012-08-13 Last updated: 2017-12-07Bibliographically approved
Rubensson, J.-E., Söderström, J., Binggeli, C., Gråsjö, J., Andersson, J., Sathe, C., . . . Pietzsch, A. (2015). Rydberg-Resolved Resonant Inelastic Soft X-Ray Scattering: Dynamics at Core Ionization Thresholds. Physical Review Letters, 114(13), Article ID 133001.
Open this publication in new window or tab >>Rydberg-Resolved Resonant Inelastic Soft X-Ray Scattering: Dynamics at Core Ionization Thresholds
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2015 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 114, no 13, article id 133001Article in journal (Refereed) Published
Abstract [en]

Resonant inelastic x-ray scattering spectra excited in the immediate vicinity of the core-level ionization thresholds of N-2 have been recorded. Final states of well-resolved symmetry-selected Rydberg series converging to valence-level ionization thresholds with vibrational excitations are observed. The results are well described by a quasi-two-step model which assumes that the excited electron is unaffected by the radiative decay. This threshold dynamics simplifies the interpretation of resonant inelastic x-ray scattering spectra considerably and facilitates characterization of low-energy excited final states in molecular systems.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-251994 (URN)10.1103/PhysRevLett.114.133001 (DOI)000352073600001 ()25884123 (PubMedID)
Available from: 2015-05-11 Created: 2015-04-28 Last updated: 2017-12-04Bibliographically approved
Gråsjö, J. (2013). Molecular Arrangement, Electronic Structure and Transport Properties in Surfactant Gel- and Related Systems Studied by Soft X-ray and Dielectric Spectroscopy. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Molecular Arrangement, Electronic Structure and Transport Properties in Surfactant Gel- and Related Systems Studied by Soft X-ray and Dielectric Spectroscopy
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis concerns studies of aqueous soft matter systems, especially surfactant micelle systems.

The aim has been to study the molecular arrangement and electronic structure of the constituents of, as well as transport properties in such a system. The molecular arrangement and electronic structure has been studied by means of X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray spectroscopy (RIXS). The transport properties have been investigated by low-frequency dielectric spectroscopy (LFDS) and small angle X-ray scattering (SAXS) as well as a theoretical modelling. The latter was based on Fick’s laws of the release from binary surfactant system and was validated by experiments.

The RIXS and XAS measurements show the electronic structure in bulk water and the influence of the chemical surrounding of the water molecule in bulk water and of the water molecules confined in a micelle lattice. The spectra are highly dependent on the molecular arrangement in such systems. For glycine and sodium polyacrylate RIXS and XAS spectra show features which are unique for carboxyl and carboxylate groups and such measurements can thus be used for fingerprinting.

The LFDS and SAXS measurements show a strong correlation between structure in a surfactant/poly-ion system and apparent mobility of surfactants. This conclusion is in line with earlier observations.

By the theoretical modelling a predictive model for the surfactant release from a binary surfactant micelle system has been obtained and the importance of different factors for surfactant release has been further clarified.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. p. 77
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1060
Keywords
surfactants, surfactant/poly-ion gel, water, confined water, XAS, RIXS, dielectric spectroscopy, SAXS, pKa, transport, Fick’s law
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-205072 (URN)978-91-554-8721-8 (ISBN)
Public defence
2013-09-27, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:30 (Swedish)
Opponent
Supervisors
Available from: 2013-09-04 Created: 2013-08-13 Last updated: 2014-01-08
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