| 1. |
- Alvebratt, Caroline, et al.
(författare)
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In Vitro Performance and Chemical Stability of Lipid-Based Formulations Encapsulated in a Mesoporous Magnesium Carbonate Carrier
- 2020
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Ingår i: Pharmaceutics. - : MDPI AG. - 1999-4923. ; 12:5
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Tidskriftsartikel (refereegranskat)abstract
- Lipid-based formulations can circumvent the low aqueous solubility of problematic drug compounds and increase their oral absorption. As these formulations are often physically unstable and costly to manufacture, solidification has been suggested as a way to minimize these issues. This study evaluated the physicochemical stability and in vitro performance of lipid-loaded mesoporous magnesium carbonate (MMC) particles with an average pore size of 20 nm. A medium chain lipid was loaded onto the MMC carrier via physical adsorption. A modified in vitro lipolysis setup was then used to study lipid release and digestion with 1H nuclear magnetic resonance spectroscopy. The lipid loading efficiency with different solidification techniques was also evaluated. The MMC, unlike more commonly used porous silicate carriers, dissolved during the lipolysis assay, providing a rapid release of encapsulated lipids into solution. The digestion of the dispersed lipid-loaded MMC therefore resembled that of a coarse dispersion of the lipid. The stability data demonstrated minor degradation of the lipid within the pores of the MMC particles, but storage for three months did not reveal extensive degradation. To conclude, lipids can be adsorbed onto MMC, creating a solid powder from which the lipid is readily released into the solution during in vitro digestion. The chemical stability of the formulation does however merit further attention.
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| 2. |
- Amombo Noa, Francoise M., et al.
(författare)
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A Hexagon Based Mn(II) Rod Metal-Organic Framework – Structure, SF6 Gas Sorption, Magnetism and Electrochemistry
- 2023
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Ingår i: Chemical Communications. - : Royal Society of Chemistry. - 1359-7345 .- 1364-548X.
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Tidskriftsartikel (refereegranskat)abstract
- A manganese(II) metal-organic framework based on the hexatopic hexakis(4-carboxyphenyl)benzene, cpb6-: [Mn3(cpb)(dmf)3], was solvothermally prepared showing a Langmuir area of 438 m2/g, rapid uptake of sulfur hexafluoride (SF6) as well as electrochemical and magnetic properties, while single crystal diffraction reveals an unusual rod-MOF topology.
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| 3. |
- Amombo Noa, Francoise Mystere, 1988, et al.
(författare)
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A hexagon based Mn(ii) rod metal-organic framework - structure, SF 6 gas sorption, magnetism and electrochemistry
- 2023
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X .- 1359-7345. ; 59:15, s. 2106-2109
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Tidskriftsartikel (refereegranskat)abstract
- A manganese(ii) metal-organic framework based on the hexatopic hexakis(4-carboxyphenyl)benzene, cpb6−: [Mn3(cpb)(dmf)3], was solvothermally prepared showing a Langmuir area of 438 m2 g−1, rapid uptake of sulfur hexafluoride (SF6) as well as electrochemical and magnetic properties, while single crystal diffraction reveals an unusual rod-MOF topology.
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| 4. |
- Chang, Ribooga, et al.
(författare)
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Achieving Molecular Sieving of CO2 from CH4 by Controlled Dynamical Movement and Host–Guest Interactions in Ultramicroporous VOFFIVE-1-Ni by Pillar Substitution
- 2024
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Ingår i: Nano Letters. - 1530-6984 .- 1530-6992. ; 24:25, s. 7616-
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Tidskriftsartikel (refereegranskat)abstract
- Engineering the building blocks in metal–organic materials is an effective strategy for tuning their dynamical properties and can affect their response to external guest molecules. Tailoring the interaction and diffusion of molecules into these structures is highly important, particularly for applications related to gas separation. Herein, we report a vanadium-based hybrid ultramicroporous material, VOFFIVE-1-Ni, with temperature-dependent dynamical properties and a strong affinity to effectively capture and separate carbon dioxide (CO2) from methane (CH4). VOFFIVE-1-Ni exhibits a CO2 uptake of 12.08 wt% (2.75 mmol g–1), a negligible CH4 uptake at 293 K (0.5 bar), and an excellent CO2-over-CH4 uptake ratio of 2280, far exceeding that of similar materials. The material also exhibits a favorable CO2 enthalpy of adsorption below −50 kJ mol–1, as well as fast CO2 adsorption rates (90% uptake reached within 20 s) that render the hydrolytically stable VOFFIVE-1-Ni a promising sorbent for applications such as biogas upgrading.
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| 5. |
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| 6. |
- Chang, Ribooga, et al.
(författare)
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Structural tuning of fluorinated hybrid ultramicroporous materials (HUMs) for low-concentration CO2 capture
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Hybrid ultramicroprous materials (HUMs) with a number of different variations of the inorganic pillars as well as surface functional groups have been tested as CO2 sorbent for low-concentration CO2 capture. Specifically well-known HUM NbOFFIVE-1-Ni (NbOFFIVE=(NbOF5)2-, 1=pyz, Ni=nickel(II)) like HUMs were synthesized in this study by replaces Nb with V and Ta. Replacing the metal center from Nb to V or Ta showed that the CO2 adsorption isotherm, in particular at low partial pressures, adopted different shapes and gradient. This study shows that the CO2 adsorption properties at low partial pressures on HUMs can be affected by the metal present in the inorganic pillars.
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| 7. |
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| 8. |
- Cheung, Ocean, et al.
(författare)
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Flue gas CO2 capture with hybrid ultramicroporous materials (HUMs)
- 2023
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Ingår i: Energy transition towards carbon neutrality: 15th International Conference on Applied Energy (ICAE2023). - Doha.
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Konferensbidrag (refereegranskat)abstract
- One of the biggest drawbacks of solid physisorbents for CO2 is their poor performance at high temperatures. This is due to their relatively low heat of CO2 sorption, which drives the adsorption/desorption equilibrium to favor desorption at above ambient temperatures. We show here that Hybrid Ultramicroporous Materials (HUMs), comprised of metals coordinated to organic ligands, and inorganic pillars, are highly effective physisorbents for capture CO2 in particular at very low partial pressure and even at moderate temperatures. We fine-tuned the HUM structure using various inorganic pillars and metal centers and produced a HUM NbOFFIVE-1-Cu that can effectively physisorb CO2 at 100 °C with CO2 uptake capacity comparable to at that 30 °C. NbOFFIVE-1-Cu is also highly stable even after 45 sorption cycles with no change in its CO2 capture properties.
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| 9. |
- Cheung, Ocean, et al.
(författare)
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Visible light-triggered desorption of CO2 in green coordination polymers
- 2023
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Ingår i: Energy transistion towards carbon neutrality: 15th International Conference on Applied Energy (ICAE2023).. - Doha : ICAE.
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Konferensbidrag (refereegranskat)abstract
- Efficient, facile, and energy-efficient desorption processes are highly sought after in industrial processes. Visible light exists all around us and can be considered a ubiquitous energy source that can be used to drive photothermal processes such as the release of guest molecules from porous sorbents. Herein, we present four sustainably synthesized porous coordination polymers, M(dhbq)(H2O)2 (where dhbq = 2,5-dihydroxy-1,4-benzoquinone, and M = Fe, Mg, Mn, or Zn) with visible light photoresponsive properties. Efficient desorption of CO2 corresponding to up to 47.6 % of the total uptake capacity was achieved upon visible light irradiation for 10 min. A negligible decrease (< 97 %) in CO2 uptake was observed for up to 10 light-swing adsorption cycles and working capacities of up to 37.5 g kg- were obtained in Fe(dhbq). M(dhbq) possess highly desirable properties that make them interesting for applications related to cost-effective and energy-efficient desorption processes.
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| 10. |
- Croket, Eveline, et al.
(författare)
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Amorphous mesoporous calcium carbonate and magnesium carbonate as effective sorbents for the removal of phosphate in aqueous solutions
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this work, highly porous amorphous calcium carbonate (HPACC) and mesoporous magnesium carbonate (MMC) were tested as potential phosphate (PO43-) sorbents in water. The performance of these sorbents at a PO43- initial concentration between 0–1000 mg/L was evaluated. These highly porous materials were found to have enhanced PO43- uptake at low concentrations (<100 mg/L) when compared with commercial CaCO3 and MgCO3. The enhanced uptake on HPACC and MMC at low concentrations was due to the high surface area and the porosity of these sorbents. The presence of NaCl salt of up to 1000 mg/L had very little effect on the performance of HPACC (<10% decreased uptake capacity), but the PO43- uptake on MMC reduced to close to zero. HPACC with its high PO43- uptake at low concentration could be relevant for real-life application of PO43- ions removal from water.
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| 11. |
- Günther, Tyran, et al.
(författare)
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Redox-site accessibility of composites containing a 2D redox-active covalent organic framework : from optimization to application
- 2023
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 11:26, s. 13923-13931
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Tidskriftsartikel (refereegranskat)abstract
- Redox-active covalent organic frameworks (RACOFs) can be employed in various functional materials and enesrgy applications. A crucial performance or efficiency indicator is the percentage of redox centres that can be utilised. Herein, the term redox-site accessibility (RSA) is defined and shown to be an effective metric for developing and optimising a 2D RACOF (viz., TpOMe-DAQ made from 2,4,6-trimethoxy-1,3,5-benzenetricarbaldehyde [TpOMe] and 2,6-diaminoanthraquinone [DAQ]) as an anode material for potential organic-battery applications. Pristine TpOMe-DAQ utilises only 0.76% of its redox sites, necessitating the use of conductivity-enhancement strategies such as blending it with different conductive carbons, or performing in situ polymerisation with EDOT (3,4-ethylenedioxythiophene) to form a conductive polymer. While conductive carbon-RACOF composites showed a modest RSA improvement of 4.0%, conductive polymer-RACOF composites boosted the redox-site usage (RSA) to 90% at low mass loadings. The material and electrochemical characteristics of the conductive polymer-RACOF composite containing more-than-necessary conductive polymer showed a reduced surface area but almost identical electrochemical behaviour, compared to the optimal ratio. The high RSA of the optimally loaded composite was replicated in a RACOF-air battery with over 90% active redox sites. We believe that the reported approach and methods, which can be employed on a milligram scale, could serve as a general guide for the electrification and characterisation of RACOFs, as well as for other redox-active porous polymers.
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| 12. |
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| 13. |
- Hedbom, Daniel, 1983-, et al.
(författare)
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Influences of secondary building unit and linker functionalization on the surface properties of metal-organic framework materials: Gas sorption of SF6
- 2024
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Ingår i: ACS Spring 2024New Orleans, Louisiana & HybridMarch 17 - 21, 2024. - New Orleans, La : American Chemical Society (ACS).
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Konferensbidrag (refereegranskat)abstract
- Anthropogenic greenhouse gas emissions pose a serious threat to our environment. Therefore, the development of efficient systems to mitigate these issues is of utmost importance. In recent years, Sulphur hexafluoride (SF ) has garnered increasing attention due to its global warming potential, which greatly exceeds that of CO2 on a 100-year scale.These studies were undertaken to investigate SF6 sorption in novel metal-organic framework materials (MOFs)and how their components affect their function. First, the influence of secondary building units on coordination and sorption properties (SBUs) of SF6 on Ytterbium, Thulium, Cerium and Hafnium 1,3,6,8-tetrakis(4-carboxyphenyl) pyrene-based (TBAPy4−) MOFs was investigated. Secondly, the possibility of altering surface-chemical properties by pre-synthesis fluorination/amination of UIO-67/68 isostructures was studied.In the first case, the SF6 sorption properties of four novel, highly porous 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene-based (TBAPy4−) MOFs containing either Ytterbium, Thulium or Cerium all in the +3-oxidation state, orHafnium (+4) was studied. Pore size effects, coordination-effects on structure, and gas sportive propertieswere investigated and found to change and in some cases improve in the case of SF6 adsorbate.In the second case, the structures remain the same throughout these different changes, maintaining the Fmmcrystallographic space group characteristic for UIO-MOFs, enabling investigation of the effect of fluorination in isolation from other possible changes. While adding one more novel material. These changes in turn cause changes in SF6 working capacity, uptake, selectivity in simulated binary mixtures and isothermal enthalpy of adsorption. The influence of specific surface area on the isosteric enthalpy of adsorption revealed differences between functionalities.There is a multi-faceted purpose in these studies. The creation of novel structures contributes to the basic science and understanding of MOFs in general. There is the proposed use of MOFs as swing adsorption adsorbents and in CCUS or more specifically, SF6 sorption. In addition to these purposes, the insight into these material properties can pave the road to more advanced interactions downstream, such as direct air capture of water, in-site catalysis or similar applications. These diverse applications each have intricacies that can be addressed within MOFs and the scientific groundwork surrounding them.
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| 14. |
- Hedbom, Daniel, 1983-, et al.
(författare)
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Linker substitution in ZIF-8 and its effect on the selective uptake of the greenhouse gases CH4, CO2 and SF6
- 2021
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Ingår i: 2nd International School on Porous Materials, 21-25 June 2021.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Attempts were made to synthesize, pore size tailor, and characterize ZIF-8 and several mixed-linker ZIF structures to improve capture of the greenhouse gasses CH4, CO2, and SF6. Three experimental linkers, 2-methylbenzimidazole, 2-aminobenzimidazole, and 5-nitrobenzimidazole were chosen to gradually substitute 2-methylimidazole as the linker in ZIF-8. This substitution was intended to gradually reduce pore sizes and possibly add functionality to the apertures present in ZIF-8. ZIF-hybrids were synthesized and characterized using PXRD, FTIR, 1HNMR, SEM, sorption measurements, and subsequent IAST modeling to evaluate these changes. Hybrid ZIFs were mostly XRD-crystalline. Linker incorporation was found to be incomplete, but increasing with added linker. Sodalite topology was confirmed in ZIF-8 samples and confirmed as modified in hybrid ZIFs. The hybrid ZIFs did indeed show altered sorption results and gas selectivity.
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| 15. |
- Hendry, Abbie, et al.
(författare)
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Catalytic cracking of Etek lignin with zirconia supported metal-oxides for alkyl and alkoxy phenols recovery
- 2020
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Ingår i: Bioresource Technology. - : ELSEVIER SCI LTD. - 0960-8524 .- 1873-2976. ; 317
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Tidskriftsartikel (refereegranskat)abstract
- Alkyl and alkoxy phenols are desirable products from the catalytic depolymerisation of lignin. In this work, ex-situ catalytic pyrolysis of Etek lignin in presence of Na, Ce, NiCe, MgCe, Fe and FePd on ZrO2 was studied. The largest combined yield of monomeric phenolics and alkylphenols was produced by Na/ZrO2 catalysts. A parametric study of the most promising Na/ZrO2 then resulted in using a catalyst:lignin ratio of 3:1 at 500 degrees C as the best option, enhancing at 17.5 wt% the recovery of total phenolics including 6 wt% alkyl phenols, which is equivalent to 27.8 wt% and 9.5 wt% of the starting lignin in Etek lignin waste. The study of the catalyst basicity indicates that the mild basicity of Na/ZrO2 was mostly responsible for the enhanced mono phenols recovery. Due to formation of thermally stable Na2CO3 during pyrolysis, successful Na/ZrO2 regeneration requires temperature of 900 degrees C or higher.
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| 16. |
- Katsiotis, Christos S., et al.
(författare)
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3D-Printed Mesoporous Carrier System for Delivery of Poorly Soluble Drugs
- 2021
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Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 13:7
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Tidskriftsartikel (refereegranskat)abstract
- Fused deposition modelling (FDM) is the most extensively employed 3D-printing technique used in pharmaceutical applications, and offers fast and facile formulation development of personalized dosage forms. In the present study, mesoporous materials were incorporated into a thermoplastic filament produced via hot-melt extrusion and used to produce oral dosage forms via FDM. Mesoporous materials are known to be highly effective for the amorphization and stabilization of poorly soluble drugs, and were therefore studied in order to determine their ability to enhance the drug-release properties in 3D-printed tablets. Celecoxib was selected as the model poorly soluble drug, and was loaded into mesoporous silica (MCM-41) or mesoporous magnesium carbonate. In vitro drug release tests showed that the printed tablets produced up to 3.6 and 1.5 times higher drug concentrations, and up to 4.4 and 1.9 times higher release percentages, compared to the crystalline drug or the corresponding plain drug-loaded mesoporous materials, respectively. This novel approach utilizing drug-loaded mesoporous materials in a printed tablet via FDM shows great promise in achieving personalized oral dosage forms for poorly soluble drugs.
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| 17. |
- Lau, Elizabeth C. H. T., et al.
(författare)
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Gold-iron oxide (Au/Fe3O4) magnetic nanoparticles as the nanoplatform for binding of bioactive molecules through self-assembly
- 2023
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Ingår i: Frontiers in Molecular Biosciences. - : Frontiers Media S.A.. - 2296-889X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Nanomedicine plays a crucial role in the development of next-generation therapies. The use of nanoparticles as drug delivery platforms has become a major area of research in nanotechnology. To be effective, these nanoparticles must interact with desired drug molecules and release them at targeted sites. The design of these "nanoplatforms" typically includes a functional core, an organic coating with functional groups for drug binding, and the drugs or bioactive molecules themselves. However, by exploiting the coordination chemistry between organic molecules and transition metal centers, the self-assembly of drugs onto the nanoplatform surfaces can bypass the need for an organic coating, simplifying the materials synthesis process. In this perspective, we use gold-iron oxide nanoplatforms as examples and outline the prospects and challenges of using self-assembly to prepare drug-nanoparticle constructs. Through a case study on the binding of insulin on Au-dotted Fe3O4 nanoparticles, we demonstrate how a self-assembly system can be developed. This method can also be adapted to other combinations of transition metals, with the potential for scaling up. Furthermore, the self-assembly method can also be considered as a greener alternative to traditional methods, reducing the use of chemicals and solvents. In light of the current climate of environmental awareness, this shift towards sustainability in the pharmaceutical industry would be welcomed.
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| 18. |
- Munro, S., et al.
(författare)
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Tuning Na2ZrO3 for fast and stable CO2 adsorption by solid state synthesis
- 2020
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Ingår i: Chemical Engineering Journal. - : ELSEVIER SCIENCE SA. - 1385-8947 .- 1873-3212. ; 388
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Tidskriftsartikel (refereegranskat)abstract
- This work assessed the possibility to tune the CO2 capture performance of Na2ZrO3 with respect to CO2 uptake and CO2 sorption rate by varying the conditions used in the solid-state synthesis. The resulting Na2ZrO3 were characterized by XRD, SEM-EDS, XPS and TGA. A structural, chemical, microstructural and kinetic analysis of the Na2ZrO3-CO2 system over one cycle was performed to identify the correlation with the sorbent performance. The heating rate, the molar ratio of the Na2CO3 and ZrO2 used in the synthesis of Na2ZrO3, as well as additional powder processing steps of the reactants, all had a major impact on the sorbent's CO2 capture performance. The best performing sorbent with the highest CO2 uptake capacity (4.83 mmol CO2/g) and absorption rate (30. 5 nmmol/s) at 700 degrees C was obtained when the Na2CO3 and ZrO2 reactants were processed by ball milling varying the molar ratio of 1:1 and a synthesis heating rate of 1 degrees C/min. Under these conditions, the optimised Na2ZrO3 exhibited 86.5% conversion in 10 min with respect to the theoretical value. Na2ZrO3 synthesised using the optimised conditions as listed above were constructed with nanocrystals of similar to 20 nm in average diameter as observed using XRD (Sherrer's formula). The Na2ZrO3 synthesised in this study favoured the ionic solid-state diffusion of Na and O from the core to the surface of the material to readily react with CO2. Moreover, an excellent cyclic stability of the sorbent over 70 sorption/desorption cycles was noted after an initial decay when the CO2 cycles were shortened to 5 min.
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| 19. |
- Sun, Rui, et al.
(författare)
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Highly Porous Amorphous Calcium Phosphate for Drug Delivery and Bio-Medical Applications
- 2020
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Amorphous calcium phosphate (ACP) has shown significant effects on the biomineralization and promising applications in bio-medicine. However, the limited stability and porosity of ACP material restrict its practical applications. A storage stable highly porous ACP with Brunauer–Emmett–Teller surface area of over 400 m2/g was synthesized by introducing phosphoric acid to a methanol suspension containing amorphous calcium carbonate nanoparticles. Electron microscopy revealed that the porous ACP was constructed with aggregated ACP nanoparticles with dimensions of several nanometers. Large angle X-ray scattering revealed a short-range atomic order of <20 Å in the ACP nanoparticles. The synthesized ACP demonstrated long-term stability and did not crystallize even after storage for over 14 months in air. The stability of the ACP in water and an α-MEM cell culture medium were also examined. The stability of ACP could be tuned by adjusting its chemical composition. The ACP synthesized in this work was cytocompatible and acted as drug carriers for the bisphosphonate drug alendronate (AL) in vitro. AL-loaded ACP released 25% of the loaded AL in the first 22 days. These properties make ACP a promising candidate material for potential application in biomedical fields such as drug delivery and bone healing.
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| 20. |
- Svensson Grape, Erik, et al.
(författare)
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Efficient removal of aqueous pharmaceutical pollutants by a robust anionic zirconium ellagate framework
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Emerging organic contaminants (EOCs) in water, such as pharmaceutical compounds, are of growing environmental concern and there is a need to develop new materials and technologies for their efficient removal. A highly porous and exceptionally stable anionic zirconium ellagate metal-organic framework (MOF), denoted SU-102, was developed and utilized to remove EOCs from water, including real municipal wastewater treatment plant (WWTP) effluent. SU-102 adsorbs cationic EOCs with particularly high efficiencies and of the 17 pharmaceutical EOCs detected in WWTP effluent all 9 cationic species were removed with efficiencies of at least 79.0-99.6%, emphasizing the significance of framework charge on selectivity. As a second mechanism of EOC removal, SU-102 photodegraded the antibiotic sulfamethazine under visible light. SU-102 is synthesized from ellagic acid, an edible polyphenol building unit, highlighting the possibility of creating stable high-performance multifunctional materials from sustainably sourced plant-based components.
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| 21. |
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| 22. |
- Tikhomirov, Evgenii, et al.
(författare)
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Impact of polymer chemistry on critical quality attributes of selective laser sintering 3D printed solid oral dosage forms
- 2023
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Ingår i: International Journal of Pharmaceutics. - : Elsevier. - 2590-1567. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to investigate the influence of polymer chemistry on the properties of oral dosage forms produced using selective laser sintering (SLS). The dosage forms were printed using different grades of polyvinyl alcohol or copovidone in combination with indomethacin as the active pharmaceutical ingredient. The properties of the printed structures were assessed according to European Pharmacopoeia guidelines at different printing temperatures and laser scanning speeds in order to determine the suitable printing parameters.The results of the study indicate that the chemical properties of the polymers, such as dynamic viscosity, degree of hydrolyzation, and molecular weight, have significant impact on drug release and kinetics. Drug release rate and supersaturation can be modulated by selecting the appropriate polymer type. Furthermore, the physical properties of the dosage forms printed under the same settings are influenced by the selected polymer type, which determines the ideal manufacturing settings.This study demonstrates how the chemical properties of the polymer can determine the appropriate choice of manufacturing settings and the final properties of oral dosage forms produced using SLS.
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| 23. |
- Tikhomirov, Evgenii, et al.
(författare)
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In situ thermal image analysis of selective laser sintering for oral dosage form manufacturing
- 2023
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier. - 0731-7085 .- 1873-264X. ; 231
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Tidskriftsartikel (refereegranskat)abstract
- Additive Manufacturing (AM) is a fast-growing approach to produce personalized oral dosage forms. Even though some AM technologies are promising as alternative to conventional compounding with resulting dosage manipulation, they still suffer from a lack of quality control. Due to the high regulatory demands and standards applied to dosage forms in the case of dose accuracy and tablet properties such as friability, effective quality control is a key feature in promoting AM as a valid technology for patient-tailored medications. One of the AM techniques used is selective laser sintering, which allows for capturing the surface state layer-by-layer during the printing process. It provides the opportunity to apply non-destructive quality control based on image analysis extracting essential data at each layer of the sintering process. This work is devoted to establishing the value of data gathered via thermal image analysis for the subsequent quality control.
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| 24. |
- Tikhomirov, Evgenii, et al.
(författare)
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Selective laser sintering additive manufacturing of dosage forms : Effect of powder formulation and process parameters on the physical properties of printed tablets
- 2023
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Ingår i: International Journal of Pharmaceutics. - : Elsevier. - 0378-5173 .- 1873-3476. ; 635
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Tidskriftsartikel (refereegranskat)abstract
- Large batches of placebo and drug-loaded solid dosage forms were successfully fabricated using selective laser sintering (SLS) 3D printing in this study. The tablet batches were prepared using either copovidone (N-vinyl-2-pyrrolidone and vinyl acetate, PVP/VA) or polyvinyl alcohol (PVA) and activated carbon (AC) as radiation absorbent, which was added to improve the sintering of the polymer. The physical properties of the dosage forms were evaluated at different pigment concentrations (i.e., 0.5 and 1.0 wt%) and at different laser energy inputs. The mass, hardness, and friability of the tablets were found to be tunable and structures with greater mass and mechanical strength were obtained with increasing carbon concentration and energy input. Amorphization of the active pharmaceutical ingredient in the drug-loaded batches, containing 10 wt% naproxen and 1 wt% AC, was achieved in-situ during printing. Thus, amorphous solid dispersions were prepared in a single-step process and produced tablets with mass losses below 1 wt%. These findings show how the properties of dosage forms can be tuned by careful selection of the process parameters and the powder formulation. SLS 3D printing can therefore be considered to be an interesting and promising technique for the fabrication of personalized medicines.
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| 25. |
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| 26. |
- Tobias, Mariano Marco, et al.
(författare)
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Plasma degradation of contaminated PPE : an energy-efficient method to treat contaminated plastic waste
- 2023
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Ingår i: NPJ MATERIALS DEGRADATION. - : Springer Nature. - 2397-2106. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The use of PPE has drastically increased because of the SARS-CoV-2 (COVID-19) pandemic as disposable surgical face masks made from non-biodegradable polypropylene (PP) polymers have generated a significant amount of waste. In this work, a low-power plasma method has been used to degrade surgical masks. Several analytical techniques (gravimetric analysis, scanning electron microscopy (SEM), attenuated total reflection-infra-red spectroscopy (ATR-IR), x-ray photoelectron spectroscopy (XPS), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and wide-angle x-ray scattering (WAXS)) were used to evaluate the effects of plasma irradiation on mask samples. After 4 h of irradiation, an overall mass loss of 63 +/- 8%, through oxidation followed by fragmentation, was observed on the non-woven 3-ply surgical mask, which is 20 times faster than degrading a bulk PP sample. Individual components of the mask also showed different degradation rates. Air plasma clearly represents an energy-efficient tool for treating contaminated PPE in an environmentally friendly approach.
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| 27. |
- Wu, Xianyue, et al.
(författare)
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An investigation of the Ni/carbonate interfaces on dual function materials in integrated CO2 capture and utilisation cycles
- 2023
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Ingår i: Applied Catalysis B. - : Elsevier. - 0926-3373 .- 1873-3883. ; 338
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Tidskriftsartikel (refereegranskat)abstract
- CO2 capture and utilisation (CCU) is a promising strategy to effectively mitigate the adverse greenhouse effects caused by CO2 emissions at an industrial scale. Through a process intensification strategy known as integrated CO2 capture and utilisation (ICCU), CO2 capture and catalytic CO2 conversion can be achieved in a single process with the use of dual function materials (DFMs), which are both CO2 sorbents and CO2 conversion catalysts. Given the significantly different operating conditions of ICCU from conventional catalytic CO2 hydrogenation, the catalytic mechanism of DFMs, especially during CO2 hydrogenation, needs to be thoroughly investigated. In this study, the relationship between the nature of the Ni/carbonate interfaces and the performance of Ni-based DFMs over ICCU cycles is systematically investigated. A series of Ni/alkaline earth carbonate DFMs were synthesised with varying Ca:Mg ratios to simulate different metal-carbonate model interfaces. At 400 °C, CH4 formation with nearly 100% CH4 selectivity was achieved on Ni/CaCO3 over 15 ICCU cycles. In general, Ni/CaCO3 interfaces correspond to higher CO2 conversion and higher CH4 selectivity than Ni/MgCO3 interfaces. Such trend may be attributed to the higher surface basicity of CaO and the higher thermal stability of CaCO3. As a consequence, the hydrogenation of the Ni/CaCO3 interface proceed via the formate pathway, in which carbonates are consecutively converted to surface formates, methoxyl, methyl species and eventually desorb as methane. This reaction model is applicable to the hydrogenation of both surface carbonate and bulk carbonates, although the former proceeds with much faster kinetics. On the weakly alkaline Ni/MgCO3 interface, MgCO3 preferentially decomposes to form gaseous CO2, which is subsequently hydrogenated via the reverse-water-gas-shift pathway, with CO as the key reaction intermediate. Interestingly, in situ infrared spectroscopy shows similar surface significant species during the direct hydrogenation of DFMs and during the conventional catalytic hydrogenation of molecular CO2, suggesting that the catalytic mechanisms during the two operating regimes are highly correlated.
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| 28. |
- Åhlén, Michelle, et al.
(författare)
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CO2 and SF6 adsorption on mixed-linker ZIF-7-8s: The effect of linker substitution on gas uptake and selectivity
- 2021
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Ingår i: 8th Conference of the Federation of European Zeolite Associations (FEZA 2021), Virtual Event, July 5-9, 2021.
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Konferensbidrag (refereegranskat)abstract
- A series of mixed-linker Zeolitic Imidazolate Framework(ZIF)-7–8s constructed from varying amounts of benzimidazolate (bIm) and 2-methylimidazolate (mIm) linkers are reported in this study. We demonstrate that the particle morphology and pore size of ZIF-7–8 can be tailored by carefully adjusting the ratios between bIm and mIm linkers in the frameworks resulting in a significantly enhanced CO2 or SF6 uptake capacity and selectivity. ZIF-7–8 containing 90% bIm and 10% mIm linkers were shown to have a CO2 uptake capacity of 1.44 mmol g−1 at 293 K (1 bar) and a CO2/N2 selectivity of over 30. While ZIF-7–8 with 26% bIm and 74% mIm linkers had a SF6 uptake of 2.08 mmol g−1 at 293 K (1 bar) and a high SF6/N2 selectivity of over 40. Isosteric enthalpy of adsorption calculations and cyclic pressure-swing adsorption experiments showed that both CO2 and SF6 were physisorbed on ZIF-7–8. The adsorption of CO2 was also found to occur rapidly on all samples, with over 80% of the total uptake capacity being reached within 30 s. Detailed kinetics analysis concluded that the diffusion of CO2 and SF6 in the mixed-linker ZIF-7–8s were governed by a mixture of different mechanisms, including intracrystalline diffusion. The highly tunable sorption properties, uptake capacities and high gas selectivities of ZIF-7–8 render them as interesting candidate sorbents for certain greenhouse gases.
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| 29. |
- Åhlén, Michelle, et al.
(författare)
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Efficient SF6 capture and separation in robust gallium- and vanadium-based metal–organic frameworks
- 2023
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 11:48, s. 26435-26441
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Tidskriftsartikel (refereegranskat)abstract
- Sulfur hexafluoride (SF6) is a highly potent greenhouse gas (GHG) that is mainly emitted from high-voltage electrical applications. The global warming potential (GWP) of the gas is almost 23 000 times that of CO2 and therefore, controlling its emission and recovery is of great importance from both an environmental and economic perspective. Solid adsorbents and adsorption-based technology is a cost-effective and energy-efficient pathway to recapture SF6 from its sources, which usually consist of dilute SF6 in N2. Here, we present a group of four highly porous and robust gallium- or vanadium-based metal–organic frameworks (MOFs) with exceptional SF6 uptake and selectivity. In particular, the novel gallium 1,2,4,5-tetrakis(4-carboxlatephenyl)benzene (TCPB4−) MOF (Ga-TBAPy) possesses 1-dimensional channels of suitable size (5.2 × 8.4 Å and 5.3 × 10 Å) to adsorb up to 2.25 mmol g−1 of SF6 at 10 kPa with an excellent SF6-over-N2 selectivity of 418. Ga-TCPB also exhibits high chemical stability in aqueous and acidic media as well as in organic solvents. 3D electron diffraction (3D ED) patterns combined with high-resolution electron microscopy images were employed to investigate the structure of these water-stable and cyclable MOF SF6 adsorbents. Furthermore, this study demonstrates the possibility of using these highly stable MOFs to capture SF6 from a gas mixture as well as how MOFs can offer an alternative and efficient way to mitigate the global warming contributions from the emission of SF6.
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| 30. |
- Åhlén, Michelle, et al.
(författare)
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Gas sorption properties and kinetics of porous bismuth-based metal-organic frameworks and the selective CO2 and SF6 sorption on a new bismuth trimesate-based structure UU-200
- 2022
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Ingår i: Microporous and Mesoporous Materials. - : Elsevier. - 1387-1811 .- 1873-3093. ; 329
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Tidskriftsartikel (refereegranskat)abstract
- Bismuth-based metal-organic frameworks (Bi-MOFs) such as bismuth subgallate are important for applications ranging from medicine to gas separation and catalysis. Due to the porous nature of such Bi-MOFs, it would be valuable to understand their gas sorption and separation properties. Here, we present the gas sorption properties of three microporous Bi-MOFs, namely, CAU-17, CAU-33, and SU-101, along with a new trimesate-based structure, UU-200. We perform a detailed analysis of the sorption properties and kinetics of these Bi-MOFs. UU-200 shows good uptake capacities for CO2 (45.81 cm3 g-1 STP) and SF6 (24.69 cm3 g-1 STP) with CO2/N2 and SF6/N2 selectivities over 35 and 44, respectively at 293 K, 100 kPa. The structure of UU-200 is investigated using continuous rotation electron diffraction, and is found to be constructed with a 3D porous framework containing pores with diameters of 3.4-3.5 Å. Bi-MOFs as a group of relatively under-investigated type of MOFs, have interesting sorption properties that render them promising for greenhouse gas adsorbents with good gas uptake capacities and high selectivities.
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| 31. |
- Åhlén, Michelle, et al.
(författare)
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Low-concentration CO2 capture using metal–organic frameworks : current status and future perspectives
- 2023
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry. - 1477-9226 .- 1477-9234. ; 52:7, s. 1841-1856
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Tidskriftsartikel (refereegranskat)abstract
- The ever-increasing atmospheric CO2 level is considered to be the major cause of climate change. Although the move away from fossil fuel-based energy generation to sustainable energy sources would significantly reduce the release of CO2 into the atmosphere, it will most probably take time to be fully implemented on a global scale. On the other hand, capturing CO2 from emission sources or directly from the atmosphere are robust approaches that can reduce the atmospheric CO2 concentration in a relatively short time. Here, we provide a perspective on the recent development of metal–organic framework (MOF)-based solid sorbents that have been investigated for application in CO2 capture from low-concentration (<10 000 ppm) CO2 sources. We summarized the different sorbent engineering approaches adopted by researchers, both from the sorbent development and processing viewpoints. We also discuss the immediate challenges of using MOF-based CO2 sorbents for low-concentration CO2 capture. MOF-based materials, with tuneable pore properties and tailorable surface chemistry, and ease of handling, certainly deserve continued development into low-cost, efficient CO2 sorbents for low-concentration CO2 capture.
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| 32. |
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| 33. |
- Åhlén, Michelle, et al.
(författare)
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Pore size effect of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene-based metal-organic frameworks for enhanced SF 6 adsorption with high selectivity
- 2022
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Ingår i: Microporous and Mesoporous Materials. - : Elsevier BV. - 1387-1811 .- 1873-3093. ; 343
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic greenhouse gas emission poses as serious threat to our environment and it is therefore of utmost importance that efficient systems are developed to mitigate these issues. SF6, in particular, has attracted more attention in recent years due to its global warming potential which severely exceeds that of CO2. In this study we present the SF6 sorption properties of four highly porous 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene-based (TBAPy4−) metal-organic frameworks containing either ytterbium(III), thulium(III), cerium(III), or hafnium(IV). These MOFs can be synthesized with high crystallinity in as little as 5 h and were found to have good SF6 uptakes due to their suitable pore size. The SF6 uptake of the Yb-TBAPy MOF reached 2.33 mmol g−1 with high Henry's law SF6-over-N2 selectivity of ∼80 at 1 bar and 293 K. The TBAPy-MOFs were also found to have good chemical stability and good cyclic SF6 sorption stability with fast SF6 uptake. These TBAPy-MOFs possesses many of the properties desired for an efficient SF6 sorbent and may be suitable sorbents for further development, including sorbent processing for industrial applications.
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| 34. |
- Åhlén, Michelle, 1992-
(författare)
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Porous Sorbents for Environmental Applications and Selective Laser Sintering 3D Printing of Dosage Forms
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The rising levels of greenhouse gas emissions from vehicular and industrial pollution constitute a serious concern not only for the environment but for our entire society. Traditional gas capture and separation techniques, such as amine scrubbing for CO2 gas separation, have been commonly used at a commercial scale, however issues relating to high costs and high energy requirements for sorbent regeneration have limited the efficiency of many of these techniques. The use of porous sorbents, such as metal-organic frameworks (MOFs), has garnered significant attention as an alternative method for the capture and separation of greenhouse gases in recent years, particularly due to their structural and functional tunability. Thus, part of this thesis explores the selective capture of CO2 and SF6 in five new MOFs and mixed-linker zeolitic imidazolate frameworks (ZIFs). The CO2 and SF6 adsorption in microporous bismuth-based MOFs containing narrow ultramicro-pores (e.g. UU-200) was not found to be correlated to the N2-accessible surface area of the framework but was related to pore size effects and possibly framework flexibility. Similar mechanisms for SF6 capture were observed in vanadium- and gallium-based MOFs (UU-201-4) in which an enhanced van der Waals interaction between the gas molecules and the pore surface was obtained due to the pore size of the materials coinciding with the kinetic diameter of SF6 (5.5 Å). This further resulted in good uptake capacities as well as SF6-over-N2 selectivites above 2.75 mmol g-1 and 43, respectively. Furthermore, the selective uptake of CO2 and SF6 could be modified in mixed-linker ZIF-7-8s by tuning of the pore aperture size through a controlled incorporation of the bulkier benzimidazolate linker in the frameworks.The removal of other environmental pollutants (e.g. phosphates) in porous materials such as amorphous mesoporous magnesium carbonate (MMC) was also investigated and showed that the material had superior sorption capacities as compared to its crystalline, non-porous counterpart. MMC was also found to be a capable functional support for other materials such as semiconducting TiO2 and ZnO nanoparticles. The TiO2/ZnO-composite was observed to retain the porosity as well as UV-blocking properties of the respective pristine materials.A part of this thesis was also devoted to the fabrication of personalized solid dosage forms for pharmaceutical applications. To achieve this, 3-dimensional selective laser sintering (SLS) printing was utilized to print both purely polymeric and drug-loaded tablets (containing 10 wt.% naproxen). The subsequent weight and mechanical strength of the obtained tablets could be tuned by either modifying the NIR-active pigment concentration in the powder formulation or by changing the laser energy input that is used during the printing process. Amorphization of the crystalline drug was also achieved in-situ during printing thus showing that the SLS 3D printing may be a promising technique for the manufacturing of solid amorphous dispersions with tailorable properties.
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| 35. |
- Åhlén, Michelle, et al.
(författare)
-
Printing for medication
- 2021
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Ingår i: Additive Manufacturing for the Life Sciences Competence Centre. Consortium Meeting Spring 2021.. - Uppsala.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 36. |
- Åhlén, Michelle, et al.
(författare)
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Selective adsorption of CO2 and SF6 on mixed-linker ZIF-7–8s : The effect of linker substitution on uptake capacity and kinetics
- 2021
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 422:15
-
Tidskriftsartikel (refereegranskat)abstract
- A series of mixed-linker Zeolitic Imidazolate Framework(ZIF)-7–8s constructed from different amounts of benzimidazolate (bIm) and 2-methylimidazolate (mIm) linkers were synthesized in this study. We demonstrated that by carefully controlling the ratios between bIm and mIm linkers, the particle morphology and pore size of ZIF-7–8 can be tailored to selectively adsorb CO2 or SF6 with significantly enhanced uptake capacity. ZIF-7–8 with 90% bIm and 10% mIm linkers showed a CO2 uptake of 1.44 mmol g−1 at 293 K (1 bar) and a CO2/N2 selectivity of over 30. On the other hand, ZIF-7–8 with 26% bIm and 74% mIm linkers had a high SF6 uptake of 2.08 mmol g−1 at 293 K (1 bar) as well as a high SF6/N2 selectivity of over 40. Isosteric enthalpy of adsorption calculations and cyclic adsorption experiments confirmed that both CO2 and SF6 were physisorbed on ZIF-7–8. CO2 was found to adsorb rapidly on ZIF-7–8, with over 80% of the total uptake capacity reached within 30 s. Detailed kinetics analysis concluded that the adsorption of CO2 and SF6 on these ZIF-7–8s could be described by pseudo-second order kinetics and the diffusion was found to be governed by a mixture of different mechanisms. The highly tunable sorption properties, high uptake capacity and high selectivity of ZIF-7–8 render them as interesting candidate sorbents for different greenhouse gases.
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| 37. |
- Åhlén, Michelle, et al.
(författare)
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Selective capture and separation of potent greenhouse gases with gallium- and vanadium-based metal-organic frameworks
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Four novel metal-organic frameworks (MOFs) composed of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene (TBAPy4-) or 1,2,4,5-tetrakis(4-carboxlatephenyl)benzene (TCPB4-) linkers with gallium (Ga) or vanadium (V) were synthesized in this work. 3D electron diffraction patterns combined with high-resolution electron microscopy images were employed to investigate the structure of these MOFs. All four MOFs were highly porous with specific Langmuir surface area ranging from ~900 to over ~1800 m2 g-1. The MOFs also showed high uptake of greenhouse gas and especially selective towards SF6 (110 cm3 cm-3, 293 K 1 bar) and CO2 over N2 (or CH4). Sorption kinetics were investigated in detail and the MOF with the highest gas uptake had pore channels with diameters of approx. 9.1 13.6 and 6.5 13.7 in dimension. These Ga- and V-MOFs are potentially interesting candidate sorbents for greenhouse gas capture and separation applications, especially for the separation of SF6 and CO2 from N2, which are relevant in the electronics and chemical industry, respectively.
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| 38. |
- Åhlén, Michelle, et al.
(författare)
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Selective SF₆ adsorption and separation in pyrene-based metal-organic frameworks
- 2022
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Ingår i: Functions. - Dresden.
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Konferensbidrag (refereegranskat)abstract
- Anthropogenic greenhouse gas emission poses a serious threat to our environment and it is therefore of utmost importance that efficient systems are developed to mitigate these issues. SF6, in particular, has attracted more attention in recent years due to its global warming potential which severely exceeds that of CO2. In this study we present the SF6 sorption properties of four highly porous 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene-based (TBAPy4-) metal-organic frameworks containing either ytterbium(III), thulium(III), cerium(III), vanadium(IV), gallium(III), or hafnium(IV). These MOFs can be synthesized with high crystallinity within 24 h and were found to have good SF6 uptakes due to their suitable pore size.
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| 39. |
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