| 1. |
- Nguyen, Tho D. K., et al.
(författare)
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Quantitative Nanoscale Secondary Ion Mass Spectrometry (NanoSIMS) Imaging of Individual Vesicles to Investigate the Relation between Fraction of Chemical Release and Vesicle Size
- 2023
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Ingår i: Angewandte Chemie. - 0044-8249 .- 1521-3757. ; 62:28
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Tidskriftsartikel (refereegranskat)abstract
- We used correlative transmission electron microscopy (TEM) and nanoscale secondary ion mass spectrometry (NanoSIMS) imaging to quantify the contents of subvesicular compartments, and to measure the partial release fraction of C-13-dopamine in cellular nanovesicles as a function of size. Three modes of exocytosis comprise full release, kiss-and-run, and partial release. The latter has been subject to scientific debate, despite a growing amount of supporting literature. We tailored culturing procedures to alter vesicle size and definitively show no size correlation with the fraction of partial release. In NanoSIMS images, vesicle content was indicated by the presence of isotopic dopamine, while vesicles which underwent partial release were identified by the presence of an I-127-labelled drug, to which they were exposed during exocytosis allowing entry into the open vesicle prior to its closing again. Demonstration of similar partial release fractions indicates that this mode of exocytosis is predominant across a wide range of vesicle sizes.
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| 2. |
- Cousins, David L., et al.
(författare)
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Pyrimidin-6-yl Trifluoroborate Salts as Versatile Templates for Heterocycle Synthesis
- 2021
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 133:17, s. 9498-9501
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Tidskriftsartikel (refereegranskat)abstract
- We report a novel and general method to access a highly under‐studied privileged scaffold – pyrimidines bearing a trifluoroborate at C4, and highlight the broad utility of these intermediates in a rich array of downstream functionalization reactions. This chemistry is underpinned by the unique features of the trifluoroborate group; its robustness provides an opportunity to carry out chemoselective reactions at other positions on the pyrimidine while providing a pathway for elaboration at the C‐B bond when suitably activated.
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| 3. |
- Kao, Kun‐Che, et al.
(författare)
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A General Approach for Monolayer Adsorption of High Weight Loadings of Uniform Nanocrystals on Oxide Supports
- 2021
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Ingår i: Angewandte Chemie. - : Wiley-Blackwell Publishing Inc.. - 0044-8249 .- 1521-3757. ; 133:14, s. 8050-8058
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Tidskriftsartikel (refereegranskat)abstract
- Monodispersed metal and semiconductor nanocrystals have attracted great attention in fundamental and applied research due to their tunable size, morphology, and well-defined chemical composition. Utilizing these nanocrystals in a controllable way is highly desirable especially when using them as building blocks for the preparation of nanostructured materials. Their deposition onto oxide materials provide them with wide applicability in many areas, including catalysis. However, so far deposition methods are limited and do not provide control to achieve high particle loadings. This study demonstrates a general approach for the deposition of hydrophobic ligand-stabilized nanocrystals on hydrophilic oxide supports without ligand-exchange. Surface functionalization of the supports with primary amine groups either using an organosilane ((3-aminopropyl)trimethoxysilane) or bonding with aminoalcohols (3-amino-1,2-propanediol) were found to significantly improve the interaction between nanocrystals and supports achieving high loadings (>10 wt. %). The bonding method with aminoalcohols guarantees the opportunity to remove the binding molecules thus allowing clean metal/oxide materials to be obtained, which is of great importance in the preparation of supported nanocrystals for heterogeneous catalysis.
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| 4. |
- Karlsmo, Martin, 1995, et al.
(författare)
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High‐performant all‐organic aqueous sodium‐ion batteries enabled by PTCDA electrodes and a hybrid Na/Mg electrolyte
- 2021
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Ingår i: Angewandte Chemie - International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 60:46, s. 24709-24715
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous sodium-ion batteries (ASIBs) are aspiring candidates for low environmental impact energy storage, especially when using organic electrodes. In this respect, perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) is a promising anode active material, but it suffers from extensive dissolution in conventional aqueous electrolytes. As a remedy, we here present a novel aqueous electrolyte, which inhibits the PTCDA dissolution and enables their use as all-organic ASIB anodes with high capacity retention and Coulombic efficiencies. Furthermore, the electrolyte is based on two, hence “hybrid”, inexpensive and non-fluorinated Na/Mg-salts, it displays favourable physico-chemical properties and an electrochemical stability window >3 V without resorting to the extreme salt concentrations of water-in-salt electrolytes. Altogether, this paves the way for ASIBs with both relatively high energy densities, inexpensive total cell chemistries, long-term sustainability, and improved safety.
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| 5. |
- Ma, Le Anh, 1992-, et al.
(författare)
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Strategies for Mitigating Dissolution of Solid Electrolyte Interphases in Sodium-Ion Batteries
- 2021
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Ingår i: Angewandte Chemie International Edition. - : John Wiley & Sons. - 1433-7851 .- 1521-3773. ; 60:9, s. 4855-4863
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Tidskriftsartikel (refereegranskat)abstract
- The interfacial reactions in sodium-ion batteries (SIBs) are not well understood yet. The formation of a stable solid electrolyte interphase (SEI) in SIBs is still challenging due to the higher solubility of the SEI components compared to lithium analogues. This study therefore aims to shed light on the dissolution of SEI influenced by the electrolyte chemistry. By conducting electrochemical tests with extended open circuit pauses, and using surface spectroscopy, we determine the extent of self-discharge due to SEI dissolution. Instead of using a conventional separator, beta-alumina was used as sodium-conductive membrane to avoid crosstalk between the working and sodium-metal counter electrode. The relative capacity loss after a pause of 50 hours in the tested electrolyte systems ranges up to 30 %. The solubility of typical inorganic SEI species like NaF and Na2CO3 was determined. The electrolytes were then saturated by those SEI species in order to oppose ageing due to the dissolution of the SEI.
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| 6. |
- Zhang, Qing, et al.
(författare)
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Electron Microscopy Studies of Local Structural Modulations in Zeolite Crystals
- 2020
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Ingår i: Angewandte Chemie. - : Wiley. - 0044-8249 .- 1521-3757. ; 132:44, s. 19571-19581
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Forskningsöversikt (refereegranskat)abstract
- Zeolites are widely used in catalysis, gas separation, ion exchange, etc. due to their superior physicochemical properties, which are closely related to specific features of their framework structures. Although more than two hundred different framework types have been recognized, it is of great interest to explore from a crystallographic perspective, the atomic positions, surface terminations, pore connectivity and structural defects that deviate from the ideal framework structures, namely local structural modulation. In this article, we review different types of local modulations in zeolite frameworks using various techniques, especially electron microscopy (EM). The most recent advances in resolving structural information at the atomic level with aberration corrected EM are also presented, commencing a new era of gaining atomic structural information, not only for all tetrahedral atoms including point vacancies in framework but also for extra-framework cations and surface terminations.
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| 7. |
- Goesten, Maarten, et al.
(författare)
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Cesium's off-the-map valence orbital
- 2017
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Ingår i: Angewandte Chemie. - : Wiley. - 1521-3773 .- 1433-7851 .- 0044-8249 .- 1521-3757.
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Tidskriftsartikel (refereegranskat)abstract
- The Td-symmetric [CsO4]+ ion, featuring Cs in an oxidation state of 9, is computed to be a minimum. Cs uses outer core 5s and 5p orbitals to bind the oxygens. The valence Cs 6s orbital lies too high to be involved in bonding, and contributes to Rydberg levels only. From a Molecular Orbital perspective, the bonding scheme reminds of XeO4: an octet of electrons to bind electronegative ligands, and no low-lying acceptor orbitals on the central atom. In this sense, Cs+ resembles hypervalent Xe.
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| 8. |
- Koponen, Vera, 1968-
(författare)
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Homogeneous 1-based structures and interpretability in random structures
- 2017
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Ingår i: Mathematical logic quarterly. - : Wiley-VCH Verlagsgesellschaft. - 0942-5616 .- 1521-3870. ; 63:1-2, s. 6-18
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Tidskriftsartikel (refereegranskat)abstract
- Let V be a finite relational vocabulary in which no symbol has arity greater than 2. Let math formula be countable V-structure which is homogeneous, simple and 1-based. The first main result says that if math formula is, in addition, primitive, then it is strongly interpretable in a random structure. The second main result, which generalizes the first, implies (without the assumption on primitivity) that if math formula is “coordinatized” by a set with SU-rank 1 and there is no definable (without parameters) nontrivial equivalence relation on M with only finite classes, then math formula is strongly interpretable in a random structure.
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| 9. |
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| 10. |
- Lendel, Christofer, et al.
(författare)
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A Hexameric Peptide Barrel as Building Block of Amyloid-β Protofibrils
- 2014
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Ingår i: Angewandte Chemie. - : Wiley. - 0044-8249 .- 1521-3757. ; 126:47, s. 12970-12974
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Tidskriftsartikel (refereegranskat)abstract
- Oligomeric and protofibrillar aggregates formed by the amyloid-β peptide (Aβ) are believed to be involved in the pathology of Alzheimer’s disease. Central to Alzheimer pathology is also the fact that the longer Aβ42 peptide is more prone to aggregation than the more prevalent Aβ40. Detailed structural studies of Aβ oligomers and protofibrils have been impeded by aggregate heterogeneity and instability. We previously engineered a variant of Aβ that forms stable protofibrils and here we use solid-state NMR spectroscopy and molecular modeling to derive a structural model of these. NMR data are consistent with packing of residues 16 to 42 of Aβ protomers into hexameric barrel-like oligomers within the protofibril. The core of the oligomers consists of all residues of the central and C-terminal hydrophobic regions of Aβ, and hairpin loops extend from the core. The model accounts for why Aβ42 forms oligomers and protofibrils more easily than Aβ40.
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