| 1. |
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| 2. |
- Knudsen, Jan, et al.
(författare)
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Stroboscopic operando spectroscopy of the dynamics in heterogeneous catalysis by event-averaging
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Heterogeneous catalyst surfaces are dynamic entities that respond rapidly to changes in their local gas environment, and the dynamics of the response is a decisive factor for the catalysts’ action and activity. Few probes are able to map catalyst structure and local gas environment simultaneously under reaction conditions at the timescales of the dynamic changes. Here we use the CO oxidation reaction and a Pd(100) model catalyst to demonstrate how such studies can be performed by time-resolved ambient pressure photoelectron spectroscopy. Central elements of the method are cyclic gas pulsing and software-based event-averaging by image recognition of spectral features. A key finding is that at 3.2 mbar total pressure a metallic, predominantly CO-covered metallic surface turns highly active for a few seconds once the O2:CO ratio becomes high enough to lift the CO poisoning effect before mass transport limitations triggers formation of a √5 oxide.
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| 3. |
- Sotres, Javier, et al.
(författare)
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NanoWear of Salivary Films vs. Substratum Wettability
- 2012
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Ingår i: Journal of Dental Research. - : SAGE Publications. - 0022-0345 .- 1544-0591. ; 91:10, s. 973-978
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Tidskriftsartikel (refereegranskat)abstract
- The pellicle serves as a multifunctional protective layer, providing, e.g., lubrication and remineralization and also acting as a diffusion barrier. In addition, since the formation of the pellicle precedes the adhesion of micro-organisms, it is also important as a conditioning film. We present a novel approach to study the influence of the water wettability of solid surfaces on the strength of adsorbed salivary films. It is based on studying the wear resistance of the films with an atomic force microscope operated in the friction force spectroscopy mode. This methodology provides the strength of the films in terms of the forces needed for breaking and removing them. Our results indicate that these forces are highly dependent on the water wettability of the underlying substrata, decreasing with increasing hydrophobicity. Thus, this study provides valuable information for the design of materials exposed in the oral cavity, i.e., materials that will minimize plaque formation and be easy to clean.
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| 4. |
- Dahm, Åsa, et al.
(författare)
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Ultra-stable zeolites - a tool for in-cell chemistry
- 2004
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Ingår i: Journal of Biotechnology. - : Elsevier. - 0168-1656 .- 1873-4863. ; 111:3, s. 279-290
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Tidskriftsartikel (refereegranskat)abstract
- Ultrastable zeolite particles were used as vehicles to carry low molecular bio-active substances and macromolecules as proteins into viable cells. Zeolite particles that can be used for internalisation by phagocytosis were obtained from the non-sedimenting fraction of a commercially available zeolite preparation after 1 × g sedimentation. Protein adsorbed on the zeolite surface was shown to enter the endosomal pathway after phagocytosis and could be cleaved by the endosomal proteases. As a model of a low molecular weight bio-active molecule, the inhibitor of the cellular synthesis of nitrogen oxide, N-nitro-l-arginine methyl ester (L-NAME), was used. A partial inhibition of the cellular NO production was shown after utilizing zeolites as vehicles to introduce the inhibitor into the cells. A targeting of the intra-cellular enzymes that was at least 10 times more efficient was obtained by the use of zeolites as a carrier of the inhibitor, as opposed to addition of the inhibitor to the culture medium.
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| 5. |
- Isaksson, Simon, 1988, et al.
(författare)
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Protein-Containing Lipid Bilayers Intercalated with Size-Matched Mesoporous Silica Thin Films
- 2017
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 17:1, s. 476-485
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Tidskriftsartikel (refereegranskat)abstract
- Proteins are key components in a multitude of biological processes, of which the functions carried out by transmembrane (membrane-spanning) proteins are especially demanding for investigations. This is because this class of protein needs to be incorporated into a lipid bilayer representing its native environment, and in addition, many experimental conditions also require a solid support for stabilization and analytical purposes. The solid support substrate may, however, limit the protein functionality due to protein material interactions and a lack of physical space. We have in this work tailored the pore size and pore ordering of a mesoporous silica thin film to match the native cell-membrane arrangement of the transmembrane protein human aquaporin 4 (hAQP4). Using neutron reflectivity (NR), we provide evidence of how substrate pores host the bulky water-soluble domain of hAQP4, which is shown to extend 7.2 nm into the pores of the substrate. Complementary surface analytical tools, including quartz crystal microbalance with dissipation monitoring (QCM-D) and fluorescence microscopy, revealed successful protein-containing supported lipid bilayer (pSLB) formation on mesoporous silica substrates, whereas pSLB formation was hampered on nonporous silica. Additionally, electron microscopy (TEM and SEM), light scattering (DLS and stopped-flow), and small-angle X-ray scattering (SAXS) were employed to provide a comprehensive characterization of this novel hybrid organic-inorganic interface, the tailoring of which is likely to be generally applicable to improve the function and stability of a broad range of membrane proteins containing water-soluble domains.
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| 6. |
- Sjöström, Jesper
(författare)
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Kemicentrum vid Lunds universitet - Perspektiv på organisation och forskning vid Sveriges första storinstitution
- 2007
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Det är nu 40 år sedan Sveriges första storinstitution, Kemicentrum vid Lunds universitet, bildades 1967. Kemiämnena vid Lunds universitet, kemisektionen vid Lunds Tekniska Högskola och Alnarpsinstitutets mejeriforskning sammanfördes i ett gemensamt byggnadskomplex i norra Lund. Tidigare självständiga institutioner med lång historia och nybildade forskningsinriktningar vid LTH blev nu alla forskningsavdelningar vid en gemensam storinstitution. Denna bok ger en mångsidig beskrivning av Kemicentrum. Bland annat diskuteras vilka faktorer som kan förklara storinstitutionens tillkomst och omvandling över tid. Bokens huvudsakliga fokus ligger på Kemicentrums organisation och forskning.
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| 7. |
- Wolff, Max, et al.
(författare)
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Grazing incidence neutron scattering for the study of solid–liquid interfaces
- 2023
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Ingår i: Reference Module in Chemistry, Molecular Sciences and Chemical Engineering. - : Elsevier.
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Bokkapitel (refereegranskat)abstract
- Neutrons are characterized by a low absorption in many engineering materials. At the same time the scattering cross section of light elements, such as hydrogen and deuterium, may be large. These properties make neutron scattering experiments performed under grazing incidence geometry an excellent tool for the study of solid–liquid interfaces. In this review we describe the basic concepts of neutron reflection and grazing incidence scattering experiments as well as experimental procedures and sample cells. The full power of the method is exemplified on a range of science areas, including polymers, bio- and ionic liquid lubricants, electrolytes as well as bio-membranes or magnetic liquids.
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| 8. |
- Kroon, Martin, et al.
(författare)
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Experimental and numerical assessment of the work of fracture in injection-moulded low-density polyethylene
- 2018
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Ingår i: Engineering Fracture Mechanics. - : Elsevier BV. - 1873-7315 .- 0013-7944. ; 192, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- The fracture mechanics properties of injection-moulded low-density polyethylene (LDPE) sheets were investigated both experimentally and numerically. The total work of fracture was determined experimentally, by means of fracture mechanics testing of sheets of injection-moulded LDPE with side cracks of different lengths. A multi-specimen method, proposed by Kim and Joe (1987), was employed. The total work of fracture was estimated to 13 kJ/m2. The experiments were simulated numerically using the finite element method. Crack growth was enabled by inclusion of a cohesive zone, and the constitutive response of this zone was governed by a traction-separation law. The local (or essential) work of fracture was estimated through numerical analyses, where the initiation of crack growth was simulated and the outcome was compared to the experimental results. The local (i.e. essential) work of fracture was estimated to 1.7 kJ/m2, which is consistent with previous experimental measurements for the material in question. The total work of fracture, retrieved from the present experiments, agreed well with the far field values of the J-integral in the numerical analyses.
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| 9. |
- Liu, Mingquan, et al.
(författare)
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Molecularly Imprinted Porous Monolithic Materials from Melamine-Formaldehyde for Selective Trapping of Phosphopeptides
- 2017
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 89:17, s. 9491-9501
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Tidskriftsartikel (refereegranskat)abstract
- Thirty-five melamine-formaldehyde (MF) monolithic materials with bimodal pore distributions were synthesized in fused silica capillaries by catalyst-free polycondensation, starting with an aqueous MF precondensate, using acetonitrile as macroporogen and a variety of aliphatic polyethers and triblock copolymeric surfactants as porogens and mesoporogens, respectively. By varying the prepolymer composition and the type and molecular weights of the polymeric porogen components, a library of porous monolithic materials were produced, covering a range of meso- and macroporous properties. A multivariate evaluation revealed that the amount of surfactant was the strongest contributor to specific surface area and pore volume, and to the inversely related mesopore size, whereas the macropore dimension was mainly controlled by the amount of aliphatic polyether porogen. One of these capillary monoliths, chosen based on the combination of meso- and macropores providing optimal percolative flow and accessible surface area, was synthesiz¬ed in the presence of N-Fmoc and O-Et protected phosphoserine and phosphotyrosine, in order to prepare molecularly imprinted monoliths with surface layers selective for phosphopeptides. These imprinted monoliths were characterized alongside non-imprinted monoliths by a variety of techniques and finally evaluated by liquid chromatography-mass spectrometry in the capillary format to assess their abilities to trap and release phosphorylated amino acids and peptides from partly aqueous media. Selective enrichment of phosphorylated targets was demonstrated, suggesting that these materials could be useful as trapping media in affinity-based phosphoproteomics.
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| 10. |
- Magnani, Chiara, et al.
(författare)
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Green Topochemical Esterification Effects on the Supramolecular Structure of Chitin Nanocrystals: Implications for Highly Stable Pickering Emulsions
- 2022
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 5:4, s. 4731-4743
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Tidskriftsartikel (refereegranskat)abstract
- In nature, chitin is organized in hierarchical structures composed of nanoscale building blocks that show outstanding mechanical and optical properties attractive for nanomaterial design. For applications that benefit from a maximized interface such as nanocomposites and Pickering emulsions, individualized chitin nanocrystals (ChNCs) are of interest. However, when extracted in water suspension, their individualization is affected by ChNC self-assembly, requiring a large amount of water (above 90%) for ChNC transport and stock, which limits their widespread use. To master their individualization upon drying and after regeneration, we herein report a waterborne topochemical one-pot acid hydrolysis/Fischer esterification to extract ChNCs from chitin and simultaneously decorate their surface with lactate or butyrate moieties. Controlled reaction conditions were designed to obtain nanocrystals of a comparable aspect ratio of about 30 and a degree of modification of about 30% of the ChNC surface, under the rationale to assess the only effect of the topochemistry on ChNC supramolecular organization. The rheological analysis coupled with polarized light imaging shows how the nematic structuring is hindered by both surface ester moieties. The increased viscosity and elasticity of the modified ChNC colloids indicate a gel-like phase, where typical ChNC clusters of liquid crystalline phases are disrupted. Pickering emulsions have been prepared from lyophilized nanocrystals as a proof of concept. Our results demonstrate that only the emulsions stabilized by the modified ChNCs have excellent stability over time, highlighting that their individualization can be regenerated from the dry state.
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