| 1. |
- Borisova, Anna, et al.
(författare)
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The method of integrated kinetics and its applicability to the exo-glycosidase-catalyzed hydrolyses of p-nitrophenyl glycosides.
- 2015
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 1873-426X .- 0008-6215. ; 412, s. 43-49
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Tidskriftsartikel (refereegranskat)abstract
- In the present work we suggest an efficient method, using the whole time course of the reaction, whereby parameters kcat, Km and product KI for the hydrolysis of a p-nitrophenyl glycoside by an exo-acting glycoside hydrolase can be estimated in a single experiment. Its applicability was demonstrated for three retaining exo-glycoside hydrolases, β-xylosidase from Aspergillus awamori, β-galactosidase from Penicillium sp. and α-galactosidase from Thermotoga maritima (TmGalA). During the analysis of the reaction course catalyzed by the TmGalA enzyme we had observed that a non-enzymatic process, mutarotation of the liberated α-d-galactose, affected the reaction significantly.
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| 2. |
- Borisova, Elena, et al.
(författare)
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Micrometer-resolution X-ray tomographic full-volume reconstruction of an intact post-mortem juvenile rat lung
- 2021
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Ingår i: Histochemistry and Cell Biology. - : Springer. - 0948-6143 .- 1432-119X. ; 155, s. 215-226
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we present an X-ray tomographic imaging method that is well suited for pulmonary disease studies in animal models to resolve the full pathway from gas intake to gas exchange. Current state-of-the-art synchrotron-based tomographic phase-contrast imaging methods allow for three-dimensional microscopic imaging data to be acquired non-destructively in scan times of the order of seconds with good soft tissue contrast. However, when studying multi-scale hierarchically structured objects, such as the mammalian lung, the overall sample size typically exceeds the field of view illuminated by the X-rays in a single scan and the necessity for achieving a high spatial resolution conflicts with the need to image the whole sample. Several image stitching and calibration techniques to achieve extended high-resolution fields of view have been reported, but those approaches tend to fail when imaging non-stable samples, thus precluding tomographic measurements of large biological samples, which are prone to degradation and motion during extended scan times. In this work, we demonstrate a full-volume three-dimensional reconstruction of an intact rat lung under immediate post-mortem conditions and at an isotropic voxel size of (2.75 mu m)(3). We present the methodology for collecting multiple local tomographies with 360 degrees extended field of view scans followed by locally non-rigid volumetric stitching. Applied to the lung, it allows to resolve the entire pulmonary structure from the trachea down to the parenchyma in a single dataset. The complete dataset is available online ().
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| 3. |
- Pearce, Elena A., et al.
(författare)
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Substantial light woodland and open vegetation characterized the temperate forest biome before Homo sapiens
- 2023
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Ingår i: Science Advances. - 2375-2548. ; 9:45
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Tidskriftsartikel (refereegranskat)abstract
- The extent of vegetation openness in past European landscapes is widely debated. In particular, the temperate forest biome has traditionally been defined as dense, closed-canopy forest; however, some argue that large herbivores maintained greater openness or even wood-pasture conditions. Here, we address this question for the Last Interglacial period (129,000–116,000 years ago), before Homo sapiens–linked megafauna declines and anthropogenic landscape transformation. We applied the vegetation reconstruction method REVEALS to 96 Last Interglacial pollen records. We found that light woodland and open vegetation represented, on average, more than 50% cover during this period. The degree of openness was highly variable and only partially linked to climatic factors, indicating the importance of natural disturbance regimes. Our results show that the temperate forest biome was historically heterogeneous rather than uniformly dense, which is consistent with the dependency of much of contemporary European biodiversity on open vegetation and light woodland.
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| 4. |
- Sadd, Matthew, 1994, et al.
(författare)
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Visualization of Dissolution‐Precipitation Processes in Lithium–Sulfur Batteries
- 2022
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Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6840 .- 1614-6832. ; 12:10
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Tidskriftsartikel (refereegranskat)abstract
- In this work, light is shed on the dissolution and precipitation processes S8 and Li2S, and their role in the utilization of active material in Li-S batteries. Combining operando X-ray Tomographic Microscopy and optical image analysis, in real-time; sulfur conversion/dissolution in the cathode, the diffusion of polysulfides in the bulk electrolyte, and the redeposition of the product of the electrochemical reaction, Li2S, on the cathode are followed. Using a custom-designed capillary cell, positioning the entire cathode volume within the field of view, the conversion of elemental sulfur to soluble polysulfides during discharge is quantitatively followed. The results show the full utilization of elemental sulfur in the cathode in the initial stage of discharge, with all solid sulfur converted to soluble polysulfide species. Optical image analysis shows a rapid diffusion of polysulfides as they migrate from the cathode to the bulk electrolyte at the start of discharge and back to the cathode in the later stages of discharge, with the formation and precipitation of Li2S. The results point to the redeposition of Li2S on all available surfaces in the cathode forming a continuous insulating layer, leaving polysulfide species remaining in the electrolyte, and this is the process limiting the cell's specific capacity.
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