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  • 1.
    Flores, Eibar
    et al.
    Paul Scherrer Inst, Electrochem Lab, Energy & Environm Res Div, Villigen, Switzerland.
    Novak, Petr
    Paul Scherrer Inst, Electrochem Lab, Energy & Environm Res Div, Villigen, Switzerland.
    Jämstorp, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Paul Scherrer Inst, Electrochem Lab, Energy & Environm Res Div, Villigen, Switzerland.
    In situ and Operando Raman Spectroscopy of Layered Transition Metal Oxides for Li-ion Battery Cathodes2018In: FRONTIERS IN ENERGY RESEARCH, ISSN 2296-598X, Vol. 6, article id 82Article in journal (Refereed)
    Abstract [en]

    In situ and operando Raman spectroscopy is proposed to provide unique means for deeper fundamental understanding and further development of layered transition metal LiMO2 (M = Ni, Co, Mn) oxides suitable for Li-ion battery applications. We compare several spectro-electrochemical cell designs and suggest key experimental parameters for obtaining optimum electrochemical performance and spectral quality. Studies of the most practically relevant LiMO2 compositions are exemplified with particular focus on two experimental approaches: (1) lateral and axial Raman mapping of the electrode's (near-) surface to monitor inhomogeneous electrode reactions and (2) time-dependent single-particle spectra during cycling to analyze the LixMO2 lattice dynamics as a function of lithium content. Raman Spectroscopy is claimed to provide a unique real-time probe of the M-O bonds, which are at the heart of the electrochemistry of LiMO2 oxides and govern their stability. We highlight the need for further fundamental understanding of the relationships between the spectroscopic response and oxide lattice structure with particular emphasis on the development of a theoretical framework linking the position and intensity of the Raman bands to the local LixMO2 lattice con figuration. The use of complementary experimental techniques and model systems for validation also deserve further attention. Several novel LiMO2 compositions are currently being explored, especially containing dopings and coatings, and Raman spectroscopy could offer a highly dynamic and convenient tool to guide the formulation of high specific charge and long cycle life LiMO2 oxides for next-generation Li-ion battery cathodes.

  • 2.
    Flores, Eibar
    et al.
    Paul Scherrer Inst, Electrochem Lab, Villigen, Switzerland.
    Vonrüti, Nathalie
    Univ Bern, Dept Chem & Biochem, Bern, Switzerland.
    Novák, Petr
    Paul Scherrer Inst, Electrochem Lab, Villigen, Switzerland.
    Aschauer, Ulrich
    Univ Bern, Dept Chem & Biochem, Bern, Switzerland.
    Berg, Erik Jämstorp
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Paul Scherrer Inst, Electrochem Lab, Villigen, Switzerland.
    Elucidation of LixNi0.8Co0.15Al0.05O2 Redox Chemistry by Operando Raman Spectroscopy2018In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 30, no 14, p. 4694-4703Article in journal (Refereed)
    Abstract [en]

    The local structure evolution of LixNi0.8Co0.15Al0.05O2 (NCA) is linked to its electrochemical response during cycling (and overcharge) by operando Raman spectroscopy with findings supported by complementary techniques, such as online electrochemical mass spectrometry (OEMS) and density functional theory (DFT) phonon calculations. The vibrational motion of lattice oxygens is observed to be highly dependent on the local LixMO2 lattice environment, e.g. M—O bonding strength/length and state of lithiation x. All vibrational modes generally harden upon delithiation due to M—O bond character (ionic → covalent) evolution (disregarding an early bond softening due to Li+ vacancy formation) and evidence the important influence of the local structural lattice configuration on the electrochemical response of NCA. Although the intensities of all Raman active bands generally increase upon delithiation, a major inflection point at x = 0.2 marks the onset of a partly irreversible fundamental transition within NCA that is most likely related to electron removal from MO bonding states and partial oxidation of oxygen sublattice, which is also indicated by the observed concomitant O2 release from the particle surface. Operando Raman spectroscopy with higher time resolution provides unique possibilities for detailed studies of how chemical parameters (Li+ vacancy formation, transition metal cation concentration, and lattice doping, etc.) may govern the onset and nature of processes (such as bond character evolution and stability) that define the performance of the LixMO2 class of oxides. The further insights thus gained can be exploited to guide the development of next-generation layered cathodes for Li-ion batteries operating stably at higher voltages and capacities.

  • 3.
    Forsgren, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Jämstorp, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Bredenberg, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    A ceramic drug delivery vehicle for oral administration of highly potent opioids2010In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 99, no 1, p. 219-226Article in journal (Refereed)
    Abstract [en]

    Pellets composed of the ceramic material Halloysite and microcrystalline cellulose were synthesized with the aim of producing a drug delivery vehicle for sustained release of the opioid Fentanyl with low risk for dose dumping at oral intake of the highly potent drug. Drug release profiles of intact and crushed pellets, to simulate swallowing without or with chewing, in pH 6.8, pH 1, and in 48% ethanol were recorded in order to replicate the conditions in the small intestines, in the stomach, as well as cointake of the drug with alcohol. The drug release was analyzed by employing the Weibull equation, which showed that the release profiles were either governed by fickian diffusion (intact pellets in pH 6.8 and in ethanol) or by diffusion in a fractal or disordered pore network (intact pellets in pH 1 and crushed pellets in all solutions). A sustained release for approximately 3-4 h was obtained in all studied solutions from intact pellets, whereas crushed pellets released the drug content during approximately 2-3 h. The finding that a sustained release profile could be obtained both in alcohol and after crushing of the pellets, shows that the ceramic carrier under investigation, at least to some extent, hampers dose dumping, and may thus be a promising material in future developments of new opioid containing oral dosage forms.

  • 4. He, Minglong
    et al.
    Fic, Krzysztof
    Poznan Univ Tech, Inst Chem & Tech Electrochem, PL-60695 Poznan, Poland.
    Frackowiak, Elzbieta
    Poznan Univ Tech, Inst Chem & Tech Electrochem, PL-60695 Poznan, Poland.
    Novak, Petr
    Paul Scherrer Inst, Electrochem Lab, CH-5232 Villigen, Switzerland.
    Jämstorp, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Paul Scherrer Inst, Electrochem Lab, CH-5232 Villigen, Switzerland.
    Towards more Durable Electrochemical Capacitors by Elucidating the Ageing Mechanisms under Different Testing Procedures2019In: CHEMELECTROCHEM, ISSN 2196-0216, Vol. 6, no 2, p. 566-573Article in journal (Refereed)
    Abstract [en]

    Electrical double-layer capacitors (EDLCs) commonly denoted supercapacitors are rechargeable energy storage devices with excellent power and energy delivery metrics intermediate to conventional capacitors and batteries. High-voltage aqueous electrolyte based EDLCs are particularly attractive due to their high-power capability, facile production, and environmental advantages. EDLCs should last for thousands of cycles and evaluation of future cell chemistries require long-term and costly galvanostatic cycling. Voltage holding tests have been proposed to shorten evaluation time by accelerating cell degradation processes. Whether voltage holding can replace cycling completely remains undemonstrated. In this work, a systematic investigation of the influence of testing procedure on cell performance is presented. The state-of-the-art post-mortem and operando experimental techniques are implemented to elucidate ageing mechanisms and kinetics inside EDLC cells under different testing procedures. Carbon corrosion occurring on the positively polarized electrode leads to the lower active surface area and higher oxygen content. On the contrary, an increase of surface area and micropore volume are observed on the negatively polarized electrode. Repeated galvanostatic cycles at U<1.6 V appears to facilitate the depletion of oxygen species on the positively polarized electrode in comparison with voltage holding, which indicates a more complex degradation mechanism during cycling. Caution is advised when comparing results from different test procedures.

  • 5. Jämstorp Berg, Erik
    Diffusion Controlled Drug Release from Slurry Formed, Porous, Organic and Clay-derived Pellets2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Coronary artery disease and chronic pain are serious health issues that cause severe discomfort and suffering in society today. Antithrombotic agents and highly potent analgesics play a critical role in improving the recovery process for patients being treated for these diseases. This thesis focuses on the design and study of pellet-based drug dosage forms which allow diffusion-controlled delivery of drugs with the aim of achieving optimal therapeutic outcomes.

    A wet slurry process was used to mix the drug and the polymer and/or clay precursor excipients into a paste. The pellets were then shaped via ionotropic gelation (alginate hydrogel beads/pellets), extrusion/spheronization (halloysite clay pellets) or geopolymerization.

    The decrease in the drug diffusion rate in the alginate beads was affected by the drug's molecular size and charge and the characteristics (such as concentration and chemical structure) of the surrounding alginate gel.

    The halloysite clay pellets provided sustained release of the highly potent drug fentanyl at both gastric pH 1 and intestinal pH 6.8. As expected, crushing the pellets reduced the diffusion barrier, resulting in more rapid release (dose dumping).

    The use of mechanically strong geopolymer gels was investigated as a potential means of preventing dose dumping as a result of crushing of the dosage form. Variations in the synthesis composition resulted in drastic changes in the microstructure morphology, the porosity, the mechanical stability and the drug release rate. Pore network modeling and finite element simulations were employed to theoretically evaluate the effects of porosity and drug solubility in the geopolymer structure on the drug release process. Fitting the model parameters to experimental data showed that increased average pore connectivity, a greater pore size distribution, and increased drug solubility in the pellet resulted in an increased drug release rate. Furthermore, incorporation of pH-sensitive organic polymers in the geopolymer structure reduced the high drug release rate from the pellets at gastric pH. These results indicate that geopolymers have potential for use in pellet form; both the release rate of the drug and the mechanical stability of the pellets can be optimized to prevent dose dumping.

    List of papers
    1. Release of antithrombotic drugs from alginate gel beads
    Open this publication in new window or tab >>Release of antithrombotic drugs from alginate gel beads
    Show others...
    2010 (English)In: Current drug delivery, ISSN 1875-5704, Vol. 7, no 4, p. 297-302Article in journal (Refereed) Published
    Abstract [en]

    The aim of the present work was to evaluate alginate hydrogels in the form of spherical beads as carrier for antithrombotic drugs for future use in artificial grafts. The ionotropic gelation technique was employed to prepare beads from the L. hyperborea stipe of alginate with two different alginate concentrations and two different guluronic to manuronic acid ratios. The beads were loaded, via soaking, with three different types of low molecular weight model molecules representing drugs with antithrombotic action and their release characteristics were subsequently evaluated. The entire release process of the negatively charged model drugs under study (Salicylic acid and Hirudin), was found to be governed by diffusion, while additional electrostatic interactions between drug molecule and alginate matrix was indicated to influence the release rate of the analyzed positively charged drug molecule (Dipyridamole). It was found that the alginate hydrogel matrix imposed a decrease of the drug diffusion rate on the molecules under study as compared to the corresponding diffusion rates in water. All diffusion coefficients decreased slightly with increasing concentration of alginate and with increasing guluronic to manuronic acid ratio. The results show on the potential use of alginate gel beads when developing vehicles for release of low molecular weight antithrombotic drugs.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-130060 (URN)20695840 (PubMedID)
    Available from: 2010-08-30 Created: 2010-08-30 Last updated: 2018-11-05Bibliographically approved
    2. A ceramic drug delivery vehicle for oral administration of highly potent opioids
    Open this publication in new window or tab >>A ceramic drug delivery vehicle for oral administration of highly potent opioids
    Show others...
    2010 (English)In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 99, no 1, p. 219-226Article in journal (Refereed) Published
    Abstract [en]

    Pellets composed of the ceramic material Halloysite and microcrystalline cellulose were synthesized with the aim of producing a drug delivery vehicle for sustained release of the opioid Fentanyl with low risk for dose dumping at oral intake of the highly potent drug. Drug release profiles of intact and crushed pellets, to simulate swallowing without or with chewing, in pH 6.8, pH 1, and in 48% ethanol were recorded in order to replicate the conditions in the small intestines, in the stomach, as well as cointake of the drug with alcohol. The drug release was analyzed by employing the Weibull equation, which showed that the release profiles were either governed by fickian diffusion (intact pellets in pH 6.8 and in ethanol) or by diffusion in a fractal or disordered pore network (intact pellets in pH 1 and crushed pellets in all solutions). A sustained release for approximately 3-4 h was obtained in all studied solutions from intact pellets, whereas crushed pellets released the drug content during approximately 2-3 h. The finding that a sustained release profile could be obtained both in alcohol and after crushing of the pellets, shows that the ceramic carrier under investigation, at least to some extent, hampers dose dumping, and may thus be a promising material in future developments of new opioid containing oral dosage forms.

    National Category
    Other Materials Engineering
    Research subject
    Engineering Science with specialization in Nanotechnology and Functional Materials
    Identifiers
    urn:nbn:se:uu:diva-111786 (URN)10.1002/jps.21814 (DOI)000273151500016 ()19492338 (PubMedID)
    Available from: 2009-12-21 Created: 2009-12-21 Last updated: 2018-11-05Bibliographically approved
    3. Mechanically strong geopolymers offer new possibilities in treatment of chronic pain
    Open this publication in new window or tab >>Mechanically strong geopolymers offer new possibilities in treatment of chronic pain
    Show others...
    2010 (English)In: Journal of Controlled Release, ISSN 0168-3659, E-ISSN 1873-4995, Vol. 146, no 3, p. 370-377Article in journal (Refereed) Published
    Abstract [en]

    We propose that a clay derived class of materials, known as geopolymers, may solve the problem of finding materials for controlled release with the right combination of properties necessary for a safe and sustained oral delivery of highly potent opioids. We show that the opioid Fentanyl, and its structurally similar sedative Zolpidem, can be embedded into metakaolin based geopolymer pellets to provide prolonged release dosage forms with mechanical strengths of the same order of magnitude as that of human teeth. The results presented in the current work may open up new opportunities for future development of drug delivery for high potency drugs employing high-strength and variable-pore-structure geopolymers and materials alike.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-131243 (URN)10.1016/j.jconrel.2010.05.029 (DOI)000282398100014 ()20685295 (PubMedID)
    Available from: 2010-09-28 Created: 2010-09-28 Last updated: 2018-11-05Bibliographically approved
    4. Modeling structure-function relationships for diffusive drug transport in inert porous geopolymer matrices
    Open this publication in new window or tab >>Modeling structure-function relationships for diffusive drug transport in inert porous geopolymer matrices
    2011 (English)In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 100, no 10, p. 4338-4348Article in journal (Refereed) Published
    Abstract [en]

    A unique structure-function relationship investigation of mechanically strong geopolymer drug delivery vehicles for sustained release of potent substances is presented. The effect of in-synthesis water content on geopolymer pore structure and diffusive drug transport is investigated. Scanning electron microscopy, N(2) gas adsorption, mercury intrusion porosimetry, compression strength test, drug permeation, and release experiments are performed. Effective diffusion coefficients are measured and compared with corresponding theoretical values as derived from pore size distribution and connectivity via pore-network modeling. By solely varying the in-synthesis water content, mesoporous and mechanically strong geopolymers with porosities of 8%-45% are obtained. Effective diffusion coefficients of the model drugs Saccharin and Zolpidem are observed to span two orders of magnitude (∼1.6-120 × 10(-8) cm(2) /s), comparing very well to theoretical estimations. The ability to predict drug permeation and release from geopolymers, and materials alike, allows future formulations to be tailored on a structural and chemical level for specific applications such as controlled drug delivery of highly potent substances.

    National Category
    Pharmaceutical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-158928 (URN)10.1002/jps.22636 (DOI)000295733800024 ()21656516 (PubMedID)
    Available from: 2011-09-22 Created: 2011-09-19 Last updated: 2018-11-05Bibliographically approved
    5. Influence of drug distribution and solubility on release from geopolymer pellets: A finite element method study
    Open this publication in new window or tab >>Influence of drug distribution and solubility on release from geopolymer pellets: A finite element method study
    2012 (English)In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 101, no 5, p. 1803-1810Article in journal (Refereed) Published
    Abstract [en]

    This study investigates the influence of drug solubility and distribution on its release from inert geopolymer pellets of three different sizes (1.5 × 1.5, 3 × 6, and 6 × 6 mm), having the same geopolymer composition and containing highly potent opioid fentanyl, sumatriptan, theophylline, or saccharin. Scanning electron microscopy, nitrogen sorption, drug solubility, permeation, and release experiments were performed, and estimates of the drug diffusion coefficients and solubilities in the geopolymer matrix were derived with the aid of finite element method (FEM). FEM was further employed to investigate the effect of a nonuniform drug distribution on the drug release profile. When inspecting the release profiles for each drug, it was observed that their solubilities in the geopolymer matrix imposed a much greater influence on the drug release rate than their diffusion coefficients. Concentrating the initial drug load in FEM into nonuniformly distributed drug regions inside the matrix created drug release profiles that more closely resembled experimental data than an FEM-simulated uniform drug distribution did. The presented FEM simulations and visualization of drug release from geopolymers under varying initial and dynamic conditions should open up for more systematic studies of additional factors that influence the drug release profile from porous delivery vehicles.

    Keywords
    controlled release, solubility, diffusion, dissolution, materials science, oral drug delivery
    National Category
    Nano Technology
    Research subject
    Engineering Science with specialization in Nanotechnology and Functional Materials; Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-161810 (URN)10.1002/jps.23071 (DOI)000302800100016 ()
    Available from: 2011-11-17 Created: 2011-11-17 Last updated: 2018-11-05Bibliographically approved
    6. Polymer excipients enable sustained drug release in low pH from mechanically strong inorganic geopolymers
    Open this publication in new window or tab >>Polymer excipients enable sustained drug release in low pH from mechanically strong inorganic geopolymers
    Show others...
    2012 (English)In: Results in Pharma Sciences, ISSN 2211-2863, Vol. 2, p. 23-28Article in journal (Refereed) Published
    Place, publisher, year, edition, pages
    Elsevier, 2012
    National Category
    Pharmaceutical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-161811 (URN)10.1016/j.rinphs.2012.02.001 (DOI)
    Available from: 2011-11-17 Created: 2011-11-17 Last updated: 2018-11-05
  • 6.
    Jämstorp, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Bodin, Aase
    Gatenholm, Paul
    Jeppsson, Anders
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Release of antithrombotic drugs from alginate gel beads2010In: Current drug delivery, ISSN 1875-5704, Vol. 7, no 4, p. 297-302Article in journal (Refereed)
    Abstract [en]

    The aim of the present work was to evaluate alginate hydrogels in the form of spherical beads as carrier for antithrombotic drugs for future use in artificial grafts. The ionotropic gelation technique was employed to prepare beads from the L. hyperborea stipe of alginate with two different alginate concentrations and two different guluronic to manuronic acid ratios. The beads were loaded, via soaking, with three different types of low molecular weight model molecules representing drugs with antithrombotic action and their release characteristics were subsequently evaluated. The entire release process of the negatively charged model drugs under study (Salicylic acid and Hirudin), was found to be governed by diffusion, while additional electrostatic interactions between drug molecule and alginate matrix was indicated to influence the release rate of the analyzed positively charged drug molecule (Dipyridamole). It was found that the alginate hydrogel matrix imposed a decrease of the drug diffusion rate on the molecules under study as compared to the corresponding diffusion rates in water. All diffusion coefficients decreased slightly with increasing concentration of alginate and with increasing guluronic to manuronic acid ratio. The results show on the potential use of alginate gel beads when developing vehicles for release of low molecular weight antithrombotic drugs.

  • 7.
    Jämstorp, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Forsgren, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Bredenberg, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mechanically strong geopolymers offer new possibilities in treatment of chronic pain2010In: Journal of Controlled Release, ISSN 0168-3659, E-ISSN 1873-4995, Vol. 146, no 3, p. 370-377Article in journal (Refereed)
    Abstract [en]

    We propose that a clay derived class of materials, known as geopolymers, may solve the problem of finding materials for controlled release with the right combination of properties necessary for a safe and sustained oral delivery of highly potent opioids. We show that the opioid Fentanyl, and its structurally similar sedative Zolpidem, can be embedded into metakaolin based geopolymer pellets to provide prolonged release dosage forms with mechanical strengths of the same order of magnitude as that of human teeth. The results presented in the current work may open up new opportunities for future development of drug delivery for high potency drugs employing high-strength and variable-pore-structure geopolymers and materials alike.

  • 8.
    Jämstorp, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyström, Gustav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    On the self-discharge and degradation of polypyrrole electrodes for energy storage2011In: MRS Spring conference, San Francisco, 2011Conference paper (Refereed)
  • 9.
    Jämstorp, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Bredenberg, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influence of drug distribution and solubility on release from geopolymer pellets: A finite element method study2012In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 101, no 5, p. 1803-1810Article in journal (Refereed)
    Abstract [en]

    This study investigates the influence of drug solubility and distribution on its release from inert geopolymer pellets of three different sizes (1.5 × 1.5, 3 × 6, and 6 × 6 mm), having the same geopolymer composition and containing highly potent opioid fentanyl, sumatriptan, theophylline, or saccharin. Scanning electron microscopy, nitrogen sorption, drug solubility, permeation, and release experiments were performed, and estimates of the drug diffusion coefficients and solubilities in the geopolymer matrix were derived with the aid of finite element method (FEM). FEM was further employed to investigate the effect of a nonuniform drug distribution on the drug release profile. When inspecting the release profiles for each drug, it was observed that their solubilities in the geopolymer matrix imposed a much greater influence on the drug release rate than their diffusion coefficients. Concentrating the initial drug load in FEM into nonuniformly distributed drug regions inside the matrix created drug release profiles that more closely resembled experimental data than an FEM-simulated uniform drug distribution did. The presented FEM simulations and visualization of drug release from geopolymers under varying initial and dynamic conditions should open up for more systematic studies of additional factors that influence the drug release profile from porous delivery vehicles.

  • 10.
    Jämstorp, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Frenning, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Modeling structure-function relationships for diffusive drug transport in inert porous geopolymer matrices2011In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 100, no 10, p. 4338-4348Article in journal (Refereed)
    Abstract [en]

    A unique structure-function relationship investigation of mechanically strong geopolymer drug delivery vehicles for sustained release of potent substances is presented. The effect of in-synthesis water content on geopolymer pore structure and diffusive drug transport is investigated. Scanning electron microscopy, N(2) gas adsorption, mercury intrusion porosimetry, compression strength test, drug permeation, and release experiments are performed. Effective diffusion coefficients are measured and compared with corresponding theoretical values as derived from pore size distribution and connectivity via pore-network modeling. By solely varying the in-synthesis water content, mesoporous and mechanically strong geopolymers with porosities of 8%-45% are obtained. Effective diffusion coefficients of the model drugs Saccharin and Zolpidem are observed to span two orders of magnitude (∼1.6-120 × 10(-8) cm(2) /s), comparing very well to theoretical estimations. The ability to predict drug permeation and release from geopolymers, and materials alike, allows future formulations to be tailored on a structural and chemical level for specific applications such as controlled drug delivery of highly potent substances.

  • 11.
    Jämstorp, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Yarra, Tejaswi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Cai, Bing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Bredenberg, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Polymer excipients enable sustained drug release in low pH from mechanically strong inorganic geopolymers2012In: Results in Pharma Sciences, ISSN 2211-2863, Vol. 2, p. 23-28Article in journal (Refereed)
  • 12.
    Karlsson, Christoffer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Jämstorp, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Computational Electrochemistry Study of 16 Isoindole-4,7-diones as Candidates for Organic Cathode Materials2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 5, p. 3793-3801Article in journal (Refereed)
    Abstract [en]

    Prediction of the redox behavior of electroactive molecules enables screening of a variety of compounds and can serve as a guideline in the search for organic molecules for use as cathode materials in, for example, Li ion batteries. In this study, we present a computational strategy, based on density functional theory, to calculate redox potentials and acid dissociation constants for a series of 16 isoindole-4,7-dione (IID) derivatives. The calculations take all possible electron and proton transfers into account, and the results were found to correlate very well with electrochemical and spectroscopic measurements. The possibility of polymerizing the IID derivatives was also assessed computationally, as polymerization serves as a straightforward route to immobilize the active material. Three of the considered IIDs (5,6-dicyano-2-methyl-isoindole-4,7-dione, 5,6-dihydroxy-2-methyl-isoindole-4,7-dione, and 2-methyl-5-(trifluoromethyl)-isoindole-4,7-dione) are predicted to be particularly interesting for making polymers for organic cathodes because these are calculated to have high redox potentials and high specific capacities and to be readily polymerizable. The presented strategy is general and can be applied in the prediction of the electrochemical behavior of quinones as well as other systems involving proton and electron transfers.

  • 13.
    Karlsson, Christoffer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Jämstorp, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Isoindole-4,7-diones as Candidates for Organic Lithium Ion Battery Polymer Cathodes2012In: GRADuate School in Advanced Materials for the 21st century: Workshop 2012, February 8, 2012, Uppsala, 2012Conference paper (Refereed)
  • 14.
    Kitz, Paul G.
    et al.
    Paul Scherrer Inst, Electrochem Lab, CH-5232 Villigen, Switzerland.
    Lacey, Matthew
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Novak, Petr
    Paul Scherrer Inst, Electrochem Lab, CH-5232 Villigen, Switzerland.
    Berg, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Paul Scherrer Inst, Electrochem Lab, CH-5232 Villigen, Switzerland.
    Operando EQCM-D with Simultaneous in Situ EIS: New Insights into Interphase Formation in Li Ion Batteries2019In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 91, no 3, p. 2296-2303Article in journal (Refereed)
    Abstract [en]

    An operando electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) with simultaneous in situ electrochemical impedance spectroscopy (EIS) has been developed and applied to study the solid electrolyte interphase (SEI) formation on copper current collectors in Li-ion batteries. The findings are backed by EIS simulations and complementary analytical techniques, such as online electrochemical mass spectrometry (OEMS) and X-ray photoelectron spectroscopy (XPS). The evolution of mass and the mechanical properties of the SEI are directly correlated to the electrode impedance. Electrolyte reduction at the anode carbon active material initiates dissolution, diffusion, and deposition of reaction side products throughout the cell and increases electrolyte viscosity and the ohmic cell resistance as a result. On Cu the reduction of CuOx and HF occurs at >1.5 V and forms an initial LiF-rich interphase while electrolyte solvent reduction at <0.8 V vs Li+/Li adds a second, less rigid layer on top. Both the shear storage modulus and viscosity of the SEI generally increase upon cycling but-along with the SEI Li+ diffusion coefficient-also respond reversibly to electrode potential, likely as a result of Li+/EC interfacial concentration changes. Combined EIS-EQCM-D provides unique prospects for further studies of the highly dynamic structure-function relationships of electrode interphases in Li ion batteries.

  • 15.
    Nisar, Jawad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Århammar, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Jämstorp, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Optical gap and native point defects in kaolinite studied by the GGA-PBE, HSE functional, and GW approaches2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, no 7, p. 075120-Article in journal (Refereed)
    Abstract [en]

    The electronic structure of kaolinite with and without intrinsic defects has been studied by the Perdew-Burke-Ernzerhof (PBE) and Heyd-Scuseria-Ernzerhof (HSE) functionals and by the G(0)W(0) approach. The band gap of defect-free kaolinite was estimated to between 6.2 and 8.2 eV. Analysis of the formation energy of native point defects in kaolinite was carried out under different growth conditions. When the PBE defect formation energy as a function of temperature is considered, the hydroxyl vacancy is compensated by a hydrogen vacancy at a formation energy of 0.45 eV at oxygen-rich and hydrogen-poor conditions. The hydroxyl vacancy acts as a donor whereas the hydrogen vacancy acts as an acceptor, both inducing states in the band gap. The HSE06 hybrid functional increases the defect formation energy and tends to localize and move these states away from the band edges, as compared to the other two methods. Our results imply that intrinsic defects will tune the band gap of kaolinite and influence properties related to its band structure such as the cation retention capability and drug release.

  • 16.
    Olsson, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Berg, Erik Jämstorp
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Self-discharge in positively charged polypyrrole-cellulose composite electrodes2015In: Electrochemistry communications, ISSN 1388-2481, E-ISSN 1873-1902, Vol. 50, p. 43-46Article in journal (Refereed)
    Abstract [en]

    Self-discharge is one of the most critical issues to address to allow for industrialization of conducting polymer (CP) based electric energy storage devices. The present work investigates the underlying cause of self-discharge in positively charged polypyrrole (PPy), which is one of the most frequently studied CPs for such devices. The analyzed material is a composite of PPy and cellulose from Cladophora sp. algae forming a free standing paper-like material. From the time dependence of the potential decay as well as from independent spectroelectrochemical investigations the decay was attributed to a kinetically limiting Faradaic reaction, intrinsic to the polymer, forming a reactive intermediate that irreversibly reacts with its surroundings in a kinetically non-limiting following reaction. As such, nucleophilic addition of electrolyte nudeophiles is not found to be rate-determining. These results provide insight into the self-discharge phenomenon in p-doped CPs, and information regarding the potential range in which CPs can operate with insignificant self-discharge.

  • 17. Olsson, Henrik
    et al.
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Jämstorp Berg, Erik
    Strømme, Maria
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Self-discharge Reactions in Energy Storage Devices Based on Polypyrrole-cellulose Composite Electrodes2014In: Green, ISSN 1869-8778, Vol. 4, no 1-6, p. 27-39Article in journal (Refereed)
  • 18. Schneider, Simon F.
    et al.
    Bauer, Christian
    Novák, Petr
    Berg, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    A modeling framework to assess specific energy, costs and environmental impacts of Li-ion and Na-ion batteries2019In: Sustainable Energy & FuelsArticle in journal (Refereed)
    Abstract [en]

    Li-ion batteries (LIBs) are among the most advanced technologies for energy storage. Due to the potential criticality of lithium raw materials, Na-ion batteries (NIBs) are frequently suggested as a low-cost, environmentally benign alternative to eventually complement or even replace LIBs. Herein, we present a holistic modeling framework to assess the potential of NIB cells from a performance, cost, and environmental impact perspective. To this end, we employ a physics-based battery cell model to project practical specific energies of LIB and NIB cells subjected to varying discharge rates. The derived performance metrics are subsequently used to parameterize a bottom-up battery cell cost model and to assess life cycle greenhouse gas (GHG) emission. Benchmarking model results obtained for NIBs (NaNi1/3Co1/3Mn1/3O2 vs. hard carbon) against state-of-the-art LIBs (LiNi1/3Co1/3Mn1/3O2 vs. graphite), we find that NIBs made from currently available active materials cannot compete with LIBs in terms of performance, costs, and environmental impact. Identifying battery performance as a key parameter driving manufacturing costs and GHG emissions, we argue that in order to make NIBs competitive to LIBs, one of the main priorities of NIB research should be the development of anode and cathode materials offering specific charges, voltages, and cycle life times comparable to or higher than for LIB active materials.

1 - 18 of 18
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