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| 2. |
- Louis, B., et al.
(author)
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Fast-tracking of single emitters in large volumes with nanometer precision
- 2020
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In: Optics Express. - : Optica Publishing Group. - 1094-4087. ; 28:19, s. 28656-28671
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Journal article (peer-reviewed)abstract
- Multifocal plane microscopy allows for capturing images at different focal planes simultaneously. Using a proprietary prism which splits the emitted light into paths of different lengths, images at 8 different focal depths were obtained, covering a volume of 50x50x4 mu m(3). The position of single emitters was retrieved using a phasor-based approach across the different imaging planes, with better than 10 nm precision in the axial direction. We validated the accuracy of this approach by tracking fluorescent beads in 3D to calculate water viscosity. The fast acquisition rate (>100 fps) also enabled us to follow the capturing of 0.2 mu m fluorescent beads into an optical trap. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
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| 4. |
- Vandaele, Ann Carine, et al.
(author)
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Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter
- 2019
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In: Nature. - : Springer. - 1476-4687 .- 1476-4687 .- 0028-0836. ; 568:7753, s. 521-525
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Journal article (other academic/artistic)abstract
- Global dust storms on Mars are rare1,2 but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere3, primarily owing to solar heating of the dust3. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars4. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes5,6, as well as a decrease in the water column at low latitudes7,8. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H2O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals3. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere.
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| 5. |
- Noelle, Andreas, et al.
(author)
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UV/Vis+ photochemistry database : Structure, content and applications
- 2020
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In: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier. - 0022-4073 .- 1879-1352. ; 253
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Journal article (peer-reviewed)abstract
- The “science-softCon UV/Vis+ Photochemistry Database” (www.photochemistry.org) is a large and comprehensive collection of EUV-VUV-UV–Vis-NIR spectral data and other photochemical information assembled from published peer-reviewed papers. The database contains photochemical data including absorption, fluorescence, photoelectron, and circular and linear dichroism spectra, as well as quantum yields and photolysis related data that are critically needed in many scientific disciplines.This manuscript gives an outline regarding the structure and content of the “science-softCon UV/Vis+ Photochemistry Database”. The accurate and reliable molecular level information provided in this database is fundamental in nature and helps in proceeding further to understand photon, electron and ion induced chemistry of molecules of interest not only in spectroscopy, astrochemistry, astrophysics, Earth and planetary sciences, environmental chemistry, plasma physics, combustion chemistry but also in applied fields such as medical diagnostics, pharmaceutical sciences, biochemistry, agriculture, and catalysis. In order to illustrate this, we illustrate the use of the UV/Vis+ Photochemistry Database in four different fields of scientific endeavor.
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| 6. |
- Thys, M., et al.
(author)
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In vitro Fertilizing Capacity of Frozen-thawed Bull Spermatozoa Selected by Single-layer (Glycidoxypropyltrimethoxysilane) Silane-coated Silica Colloidal Centrifugation
- 2009
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In: Reproduction in domestic animals. - : Wiley-Blackwell. - 0936-6768 .- 1439-0531. ; 44:3, s. 390-394
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Journal article (peer-reviewed)abstract
- Barriers to the use of density gradient centrifugation for preparing animal spermatozoa for artificial insemination (AI) include the scarcity of animal-specific formulations and the daunting prospect of processing large volumes of ejaculate in small aliquots (1.5 ml extended semen). Recently, new colloid formulations have been tested in vitro in a modified procedure, centrifugation on a single layer of colloid. The present study investigated the fertilizing ability during in vitro fertilization (IVF) of frozen-thawed bovine spermatozoa following centrifugation through a single layer of glycerolpropylsilane (GS)-coated silica colloid with a species-specific formulation (patent applied for; treatment, T). Controls (C) included centrifugation through gradients of either the same colloid (C1) or Percoll (TM) (C2). Sperm recovery surpassed 50% for both C1-C2 and T (n.s.). Mean values of various parameters of computerized analysis of sperm motility did not differ between T and C1 (n.s.), and only the proportions of path straightness and linearity were lower in T vs C2 (p less than 0.05). In T, the mean (+/- SD) percentages of fertilization rate, blastocyst development rate and the total number of blastomeres were 58.1 +/- 23.3%, 24.5 +/- 14.3% and 94.6 +/- 23.4%, respectively. The proportions did not differ significantly from controls (C1/C2). Therefore, centrifugation through a single layer of colloid offers an alternative method to density gradient centrifugation for selection of viable, potentially fertile frozen-thawed bull spermatozoa. This single-layer technique is gentle, versatile and convenient because it facilitates scaling-up the process of sperm preparation to allow larger numbers of spermatozoa (for instance, whole ejaculates) to be processed for AI.
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| 7. |
- Vandaele, Johannes, et al.
(author)
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Structural characterization of fibrous synthetic hydrogels using fluorescence microscopy
- 2020
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In: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 16:17, s. 4210-4219
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Journal article (peer-reviewed)abstract
- The structural features of the matrix surrounding the cells play a crucial role in regulating their behavior. Here, we used fluorescence microscopy and customized analysis algorithms to characterize the architecture of fibrous hydrogel networks. As a model system, we investigated a new class of synthetic biomimetic material, hydrogels prepared from polyisocyanides. Our results show that these synthetic gels present a highly heterogeneous fibrous network, with pores reaching a few micrometers in diameter. By encapsulating HeLa cells in different hydrogels, we show that a more porous structure is linked to a higher proliferation rate. The approach described here, for the characterization of the network of fibrous hydrogels, can be easily applied to other polymer-based materials and provide new insights into the influence of structural features in cell behavior. This knowledge is crucial to develop the next generation of biomimetic materials for 3D cell models and tissue engineering applications.
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| 8. |
- Yuan, Hongbo, et al.
(author)
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Synthetic fibrous hydrogels as a platform to decipher cell–matrix mechanical interactions
- 2023
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In: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424. ; 120:15
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Journal article (peer-reviewed)abstract
- Cells continuously sense external forces from their microenvironment, the extracellular matrix (ECM). In turn, they generate contractile forces, which stiffen and remodel this matrix. Although this bidirectional mechanical exchange is crucial for many cell functions, it remains poorly understood. Key challenges are that the majority of available matrices for such studies, either natural or synthetic, are difficult to control or lack biological relevance. Here, we use a synthetic, yet highly biomimetic hydrogel based on polyisocyanide (PIC) polymers to investigate the effects of the fibrous architecture and the nonlinear mechanics on cell–matrix interactions. Live-cell rheology was combined with advanced microscopy-based approaches to understand the mechanisms behind cell-induced matrix stiffening and plastic remodeling. We demonstrate how cell-mediated fiber remodeling and the propagation of fiber displacements are modulated by adjusting the biological and mechanical properties of this material. Moreover, we validate the biological relevance of our results by demonstrating that cellular tractions in PIC gels develop analogously to those in the natural ECM. This study highlights the potential of PIC gels to disentangle complex bidirectional cell–matrix interactions and to improve the design of materials for mechanobiology studies.
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