| 1. |
- Arsana, Komang G.Y., et al.
(författare)
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Laboratory Liquid-Jet X-ray Microscopy and X-ray Fluorescence Imaging for Biomedical Applications
- 2024
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 25:2
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Tidskriftsartikel (refereegranskat)abstract
- Diffraction-limited resolution and low penetration depth are fundamental constraints in optical microscopy and in vivo imaging. Recently, liquid-jet X-ray technology has enabled the generation of X-rays with high-power intensities in laboratory settings. By allowing the observation of cellular processes in their natural state, liquid-jet soft X-ray microscopy (SXM) can provide morphological information on living cells without staining. Furthermore, X-ray fluorescence imaging (XFI) permits the tracking of contrast agents in vivo with high elemental specificity, going beyond attenuation contrast. In this study, we established a methodology to investigate nanoparticle (NP) interactions in vitro and in vivo, solely based on X-ray imaging. We employed soft (0.5 keV) and hard (24 keV) X-rays for cellular studies and preclinical evaluations, respectively. Our results demonstrated the possibility of localizing NPs in the intracellular environment via SXM and evaluating their biodistribution with in vivo multiplexed XFI. We envisage that laboratory liquid-jet X-ray technology will significantly contribute to advancing our understanding of biological systems in the field of nanomedical research.
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| 2. |
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| 3. |
- Berglund, M., et al.
(författare)
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Compact water-window transmission X-ray microscopy
- 2000
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Ingår i: Journal of Microscopy. - : Wiley. - 0022-2720 .- 1365-2818. ; 197, s. 268-273
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate sub-100 nm resolution water-window soft X-ray full-field transmission microscopy with a compact system. The microscope operates at lambda = 3.37 nm and is based on a 100 Hz table-top regenerative debris-free droplet-target laser-plasma X-ray source in combination with normal-incidence multilayer condenser optics for sample illumination. High-spatial-resolution imaging is performed with a 7.3% efficiency nickel zone plate and a 1024 x 1024 pixel CCD detector. Images of dry test samples are recorded with exposure times of a few minutes and show features smaller than 60 nm.
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| 4. |
- Bertilson, Michael C., et al.
(författare)
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Zone plate efficiency measurements with a laser-plasma source
- 2007
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Ingår i: Advances in X-Ray/EUV Optics and Components II. - : SPIE. - 9780819468536 ; , s. F7050-F7050
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a compact instrument for rapid and accurate measurements of the absolute and local efficiency of soft x-ray zone plates in the water window [M. Bertilson, et al, Rev. Sci. Instrum 78, 026103 (2007)]. The arrangement is based on a new single-line lambda = 2.88 nm liquid-nitrogen-jet laser-plasma source. The versatility of the instrument enables micro and condenser zone plates with focal lengths in the range from similar to 200 mu m to similar to 100 mm to be measured. We demonstrate an accurate local efficiency map of a in-house fabricated micro zone plate. Furthermore, we show how this compact instrument allows rapid feedback to the fabrication process which is important for future improvements.
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| 5. |
- Bertilson, Michael, et al.
(författare)
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Compact high-resolution differential interference contrast soft x-ray microscopy
- 2008
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 92:064104
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate high-resolution x-ray differential interference contrast (DIC) in a compact soft x-ray microscope. Phase contrast imaging is enabled by the use of a diffractive optical element objective which is matched to the coherence conditions in the microscope setup. The performance of the diffractive optical element objective is evaluated in comparison with a normal zone plate by imaging of a nickel siemens star pattern and linear grating test objects. Images obtained with the DIC optic exhibit typical DIC enhancement in addition to the normal absorption contrast. Contrast transfer functions based on modulation measurements in the obtained images show that the DIC optic gives a significant increase in contrast without reducing the spatial resolution. The phase contrast operation mode now available for our compact soft x-ray microscope will be a useful tool for future studies of samples with low absorption contrast.
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| 6. |
- Bertilson, Michael, et al.
(författare)
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First application experiments with the Stockholm compact soft x-ray microscope
- 2009
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 186
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Tidskriftsartikel (refereegranskat)abstract
- Most soft x-ray microscopes operating in the water window (lambda = 2.3 - 4.4 nm) rely on synchrotron radiation sources. In the future we believe scientists will use soft x-ray microscopes as one imaging tool among others in their own laboratory. For this purpose we have developed a full field soft x-ray microscope with a laser-plasma source compact enough to fit on an optical table. In this contribution we describe the current status of this microscope now featuring stable operation at lambda = 3.37 nm or lambda = 2.48 nm. In-house fabricated single element zone plates offering the possibility to perform phase contrast imaging have been implemented. We also report on the first application experiments for compact soft x-ray microscopy, including results from studies of clay minerals and colloids existing in nature and results from phase optics experiments. Planned upgrades of the microscope include increasing the source brightness, implementing more efficient condenser optics, and installing a cryo sample stage for tomography. These improvements will open up for further applications, especially in the field of biological imaging.
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| 7. |
- Bertilson, Michael, et al.
(författare)
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High-resolution computed tomography with a compact soft x-ray microscope
- 2009
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Ingår i: Optics Express. - 1094-4087. ; 17:13, s. 11057-11065
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Tidskriftsartikel (refereegranskat)abstract
- Computed tomography based on high-resolution soft x-ray microscopy utilizes the natural contrast for biological specimens provided by the water window (lambda = 2.4 - 4.4 nm) and the high resolving power of zone plate objectives. It is capable of revealing the 3D structure of biological specimens at sub-visible-microscopic resolution. To date, the technique has only been available at synchrotron-based microscopes, which limits the researchers access. In the present paper we demonstrate high-resolution soft x-ray tomography with a laboratory zone-plate-based soft x-ray microscope. The specimen, a diatom mounted on a glass capillary, was reconstructed from a tilt series of 53 images covering 180 using a filtered back projection algorithm. The resolution of the tomogram was estimated to a half period of 140 nm using a differential-phase-residual method. Cryo-fixation, increased source brightness and extended-depth-of-focus objectives are important for pushing the resolution of compact systems for biological samples.
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| 8. |
- Bertilson, Michael, et al.
(författare)
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Laboratory Soft X-Ray Cryo Tomography
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- X-rays allow quantitative high-spatial-resolution three-dimensional (3D) imaging of intact unstained cells. Such 3D imaging is provided by soft x-ray lens-based methods (water-window cryo tomography) and hard x-ray lens-less methods (coherent diffraction imaging) are emerging. However, both methods rely on high-brightness synchrotron-radiation sources, which limit the accessibility of a wider scientific community. Here we show 3D water-window cryo tomography with a laboratory-source-based microscope arrangement. The system relies on a λ=2.48-nm liquid-jet laser-plasma source, normal- incidence multilayer condenser optics, 30-nm zone-plate optics, and a cryo sample chamber. We demonstrate imaging of intact unstained yeast, protozoan parasites and mammalian cells. 3D images show noise-limited features close to ~100 nm and intra-cellular structure is classified based on the local absorption coefficient. A comprehensive theoretical model of the tomographic imaging system allows optimization of system parameters and a quantitative estimate of the 3D imaging accuracy. The model includes issues such as non-geometric projections of the thick samples and stray light, and is applicable to laboratory as well as synchrotron-based x-ray microscopes. The model shows that laboratory x-ray cryo tomography will allow quantitative 3D imaging with ~30-nm (half-period) resolution over a full 5 µm object.
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| 9. |
- Bertilson, Michael, et al.
(författare)
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Laboratory soft-x-ray microscope for cryotomography of biological specimens
- 2011
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 36:14, s. 2728-2730
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Tidskriftsartikel (refereegranskat)abstract
- Soft-x-ray cryotomography allows quantitative and high-resolution three-dimensional imaging of intact unstained cells. To date, the method relies on synchrotron-radiation sources, which limits accessibility for researchers. Here we present a laboratory water-window microscope for cryotomography. It is based on a lambda = 2.48nm liquid-jet laser-plasma source, a normal-incidence multilayer condenser, a 30nm zone-plate objective, and a cryotilt sample holder. We demonstrate high-resolution imaging, as well as quantitative tomographic imaging, of frozen intact cells. The reconstructed tomogram of the intracellular local absorption coefficient shows details down to similar to 100nm.
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| 10. |
- Bertilson, Michael, 1979-
(författare)
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Laboratory soft x-ray microscopy and tomography
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Soft x-ray microscopy in the water-window (λ = 2.28 nm – 4.36 nm) is based on zone-plate optics and allows high-resolution imaging of, e.g., cells and soils in their natural or near-natural environment. Three-dimensional imaging is provided via tomographic techniques, soft x-ray cryo tomography. However, soft x-ray microscopes with such capabilities have been based on large-scale synchrotron x‑ray facilities, thereby limiting their accessibility for a wider scientific community. This Thesis describes the development of the Stockholm laboratory soft x-ray microscope to three-dimensional cryo tomography and to new optics-based contrast mechanisms. The microscope relies on a methanol or nitrogen liquid-jet laser-plasma source, normal-incidence multilayer or zone-plate condenser optics, in-house fabricated zone-plate objectives, and allows operation at two wavelengths in the water-window, λ = 2.48 nm and λ = 2.48 nm. With the implementation of a new state-of-the-art normal-incidence multilayer condenser for operation at λ = 2.48 nm and a tiltable cryogenic sample stage the microscope now allows imaging of dry, wet or cryo-fixed samples. This arrangement was used for the first demonstration of laboratory soft x-ray cryo microscopy and tomography. The performance of the microscope has been demonstrated in a number of experiments described in this Thesis, including, tomographic imaging with a resolution of 140 nm, cryo microscopy and tomography of various cells and parasites, and for studies of aqueous soils and clays. The Thesis also describes the development and implementation of single-element differential-interference and Zernike phase-contrast zone-plate objectives. The enhanced contrast provided by these optics reduce exposure times or lowers the dose in samples and are of major importance for harder x-ray microscopy. The implementation of a high-resolution 50 nm compound zone-plate objective for sub-25-nm resolution imaging is also described. All experiments are supported by extensive numerical modelling for improved understanding of partially coherent image formation and stray light in soft x-ray microscopes. The models are useful tools for studying effects of zone plate optics or optical design of the microscope on image formation and quantitative accuracy in soft x-ray tomography.
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| 11. |
- Bertilson, Michael, et al.
(författare)
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Numerical model for tomographic image formation in transmission x-ray microscopy
- 2011
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Ingår i: Optics Express. - 1094-4087. ; 19:12, s. 11578-11583
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Tidskriftsartikel (refereegranskat)abstract
- We present a numerical image-formation model for investigating the influence of partial coherence, sample thickness and depth-of-focus on the accuracy of tomographic reconstructions in transmission x-ray microscopes. The model combines wave propagation through the object by finite difference techniques with Fourier methods. We include a ray-tracing model to analyse the origin of detrimental stray light in zone plate-based x-ray microscopes. These models allow optimization of x-ray microscopy systems for quantitative tomographic imaging of thick objects. Results show that both the depth-of-focus and the reconstructed local absorption coefficient are highly dependent on the degree of coherence of the optical system.
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| 12. |
- Bertilsson, Michael, et al.
(författare)
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Laboratory arrangement for soft x-ray zone-plate efficiency measurements
- 2007
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 78:2, s. 026103-
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a laboratory-scale arrangement for rapid and accurate measurements of the absolute and local efficiency of soft x-ray micro zone plates in the water window. This in-house instrument is based on a single-line lambda=2.88 nm liquid-jet laser-plasma source. Measurements are performed by a simultaneous comparison of first diffraction-order photon flux with the flux in a calibrated reference signal. This arrangement eliminates existing source emission fluctuations. The performance of the method is demonstrated by the result from measurements of two similar to 55 mu m diameter nickel micro zone plates, showing a groove efficiency of 12.9%+/- 1.1% and 11.7%+/- 1.0%. Furthermore, we show that spatially resolved efficiency mapping is an effective tool for a detailed characterization of local zone plate properties. Thus, this laboratory-scale instrument allows rapid feedback to the fabrication process which is important for future improvements.
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| 13. |
- Birch, Jens, et al.
(författare)
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Recent advances in ion-assisted growth of Cr/Sc multilayer X-ray mirrors for the water window
- 2002
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Ingår i: Vacuum. - 0042-207X .- 1879-2715. ; 68:3, s. 275-282
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Tidskriftsartikel (refereegranskat)abstract
- Cr/Sc multilayer X-ray mirrors intended for normal incidence reflection in the water window wavelength range, lambda=[2.4-4.4 nm], have been grown by ion-assisted sputter deposition and characterized using soft and hard X-ray reflectivity. By extracting low-energy ions, with energies, E-ion, ranging from 9 to 113 eV and with ion-to-metal flux ratios, Phi, between 0.76 and 23.1, from the sputtering plasma to the growing film, the nano-structure of the multilayer interfaces could be modified. A significantly increased soft X-ray reflectivity, using lambda = 3.374 nm, for Cr/Sc multilayers with layer thicknesses in the range 0.4-2.8 nm, was obtained when high ion-to-metal flux ratios, Phi(Cr) = 7.1 and Phi(Sc) = 23.1, and low energy ions, E-ion = 9eV, were used. An experimental reflectivity of 5.5% was obtained at 76degrees for a multilayer with 400 bi-layers. Simulations of the reflectivity data showed that the interface widths are < 0.425 nm. It could be concluded that roughness of low spatial frequency is reduced at lower ion energies than the high spatial frequency which was eliminated at the expense of intermixing at the interfaces at higher ion energies. The predicted performance of normal incidence multilayer mirrors grown at optimum conditions and designed for lambda = 3.374 and 3.115 nm indicates possible reflectivities of 6.5% and 14%, respectively.
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| 14. |
- Burvall, Anna, et al.
(författare)
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Phase retrieval in X-ray phase-contrast imaging suitable for tomography
- 2011
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Ingår i: Optics Express. - 1094-4087. ; 19:11, s. 10359-10376
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Tidskriftsartikel (refereegranskat)abstract
- In-line phase-contrast X-ray imaging provides images where both absorption and refraction contribute. For quantitative analysis of these images, the phase needs to be retrieved numerically. There are many phase-retrieval methods available. Those suitable for phase-contrast tomography, i.e., non-iterative phase-retrieval methods that use only one image at each projection angle, all follow the same pattern though derived in different ways. We outline this pattern and use it to compare the methods to each other, considering only phase-retrieval performance and not the additional effects of tomographic reconstruction. We also outline derivations, approximations and assumptions, and show which methods are similar or identical and how they relate to each other. A simple scheme for choosing reconstruction method is presented, and numerical phase-retrieval performed for all methods.
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| 15. |
- Burvall, Anna, et al.
(författare)
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Phase-retrieval methods with applications in composite-material tomography
- 2013
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Ingår i: 11th International Conference On X-Ray Microscopy (XRM2012). - : Institute of Physics Publishing (IOPP). ; , s. 012015-
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Konferensbidrag (refereegranskat)abstract
- In-line phase-contrast x-ray imaging is emerging as a method for observing small details when the contrast in absorption x-ray imaging is low. It gives images with strong edge enhancement, and phase retrieval is necessary to obtain quantitative thickness information. In particular for tomography, clarity can be enhanced by phase retrieval, as here demonstrated on a 3D-weave reinforced composite material. Seven suitable phase-retrieval methods are identified and integrated into a single method, where each version is marked by variations in particular steps. The general method and its variations are outlined and a comparison shows which methods are most suitable in different situations.
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| 16. |
- Burvall, Anna, et al.
(författare)
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X-ray in-line phase retrieval for tomography
- 2012
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE - International Society for Optical Engineering. - 9780819489623 ; , s. 83136A-
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Konferensbidrag (refereegranskat)abstract
- Phase contrast in X-ray imaging offers imaging of fine features at lower doses than absorption. Of the phasecontrast methods in use in-line phase contrast is interesting due to its experimental simplicity, but to extract information on absorption and phase distributions from the resulting images, phase retrieval is needed. Many phase-retrieval methods suitable for different situations have been developed, but few comparisons of those methods done. We consider a sub-group of phase-retrieval methods that are suitable for tomography, i.e., that use only one exposure (for practical experimental reasons) and are non-iterative (for speed). In total we have found seven suitable methods in the literature. All, though derived in different ways under different assumptions, follow the same pattern and can be outlined as a single method where each specific version is marked by variations in particular steps. We summarize this unified approach, and give the variations of the individual methods. In addition, we outline approximations and assumptions of each method. Using this approach it is possible to conclude which specific algorithms are most suitable in specific situations and to test this based on simulated and experimental data. Ultimately, this leads to conclusions on which methods are the most suitable in different situations.
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| 17. |
- Chubarova, Elena, et al.
(författare)
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Platinum zone plates for hard X-ray applications
- 2011
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 88:10, s. 3123-3126
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Tidskriftsartikel (refereegranskat)abstract
- We describe the fabrication and evaluation of platinum zone plates for 5–12 kV X-ray imaging and focusing. These nano-scale circular periodic structures are fabricated by filling an e-beam generated mold with Pt in an electroplating process. The plating recipe is described. The resulting zone plates, having outer zone widths of 100 and 50 nm, show good uniformity and high aspect ratio. Their diffraction efficiencies are 50–70% of the theoretical, as measured at the European Synchrotron Radiation Facility. Platinum shows promise to become an attractive alternative to present hard X-ray zone plate materials due to its nano-structuring properties and the potential for zone-plate operation at higher temperatures.
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| 18. |
- de Groot, J., et al.
(författare)
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Capillary nozzles for liquid-jet laser-plasma x-ray sources
- 2003
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 74:8, s. 3881-3882
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Tidskriftsartikel (refereegranskat)abstract
- We describe a method to fabricate tapered glass nozzles suitable for liquid-jet-target generation in laser-plasma soft x-ray and extreme ultraviolet sources. In the method, a tapered nozzle is formed as an integral part of a flexible capillary glass tubing. The method makes use of inert materials, extending the possible choice of target liquids compared to current nozzles. It also provides flexibility as regards nozzle diameter and pressure, thereby allowing optimization of the target size and extending the range of applicability for the liquid-jet-target laser plasmas.
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| 19. |
- de Groot, J., et al.
(författare)
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Improved liquid-jet laser-plasma source for X-ray microscopy
- 2003
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Ingår i: Journal de Physique IV. - : EDP Sciences. - 1155-4339 .- 1764-7177. ; 104, s. 121-122
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Tidskriftsartikel (refereegranskat)abstract
- We increase the x-ray flux from a liquid-jet laser-plasma x-ray source by optimizing the target geometry. A new nozzle fabrication method allows us to produce stable microscopic liquid jets with a wide range of diameters. The improved x-ray flux is demonstrated by optimizing the diameter of an ethanol liquid-jet for our 3 ns, square=532 nm Nd:YAG laser and measuring the flux at the square=3.37 rim C VI emission line. Preliminary data suggest that the x-ray flux can be increased by more than a factor of 4 compared to previous experiments. The goal is to significantly reduce the exposure time of our laser-plasma-based compact x-ray microscope by improving the source.
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| 20. |
- de Groot, J., et al.
(författare)
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Target optimization of a water-window liquid-jet laser-plasma source
- 2003
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 94:6, s. 3717-3721
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Tidskriftsartikel (refereegranskat)abstract
- We optimize the water-window x-ray flux and debris deposition for a liquid-jet laser plasma source by varying both the target diameter and the jet material. For two target liquids, methanol and ethanol, measurements of the lambda = 3.37 nm C vi x-ray flux and the debris deposition rates are presented as function of the jet diameter. It is shown that the effective carbon debris deposition is more than I order of magnitude smaller for methanol, while the x-ray flux is reduced only similar to40%. The reduction in carbon debris deposition may be explained by reactive ion etching by oxygen from the plasma. Thus, the methanol water-window source may be operated at a 5-10X higher flux without increasing the debris deposition. The optimization potentially allows a reduction of the exposure time of compact soft x-ray microscopy or other water-window applications based on such sources without increasing damage to sensitive x-ray optics.
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| 21. |
- Eriksson, Fredrik, et al.
(författare)
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14.5% near-normal incidence reflectance of Cr/Sc x-ray multilayer mirrors for the water window
- 2003
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 28:24, s. 2494-2496
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Tidskriftsartikel (refereegranskat)abstract
- Cr/Sc multilayer mirrors, synthesized by ion-assisted magnetron sputter deposition, are proved to have a high near-normal reflectivity of R = 14.5% at a grazing angle of 87.5degrees measured at the wavelength A = 3.11 nm, which is an improvement of more than 31% compared with previously published results. Elastic recoil detection analyses show that the mirrors contained as much as 15 at. % of N and traces of C and O. Soft x-ray reflectivity simulations reveal interface widths of sigma = 0.34 nm and an exceptionally small layer thickness drift of similar to1.6 X 10(-5) nm/multilayer period throughout the stack. Simulations show that a reflectivity of R = 25.6% is attainable if impurities and layer thickness drift can be eliminated. The abrupt interfaces are achieved with ion assistance with a low ion energy of 24 eV and high ion-to-metal flux ratios of 7.1 and 23.1 during Cr and Se sputter deposition, respectively. In addition, a near-normal incidence reflectivity of 5.5% for the C VI emission line (lambda = 3.374 nm) from a laser plasma source was verified.
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| 22. |
- Eriksson, Fredrik, et al.
(författare)
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Enhanced soft x-ray reflectivity of Cr/Sc multilayers by ion-assisted sputter deposition
- 2002
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Ingår i: Optical Engineering. - : SPIE-Intl Soc Optical Eng. - 0091-3286 .- 1560-2303. ; 41:11, s. 2903-2909
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Tidskriftsartikel (refereegranskat)abstract
- Cr/Sc multilayers have been grown on Si substrates using dc magnetron sputtering. The multilayers are intended as condenser mirrors in a soft x-ray microscope operating at the wavelength 3.374 nm. They were designed for normal reflection of the first and second orders, with multilayer periods of 1.692 and 3.381 nm, and layer thickness ratios of 0,471 and 0.237, respectively. At-wavelength soft-x-ray reflectivity measurements were carried out using a reflectometer with a compact soft-x-ray laser-plasma source. The multilayers were irradiated during growth with Ar ions, varying both in energy (9 to 113 eV) and flux, in order to stimulate the adatom mobility and improve the interface flatness. It was found that to obtain a maximum soft x-ray reflectivity with a low flux (Cr=0.76, Sc=2.5) of Ar ions a rather high energy of 53 eV was required, Such energy also caused intermixing of the layers. By the use of a solenoid surrounding the substrate, the arriving ion-to-metal flux ratio could be increased 10 times and the required ion energy could be decreased. A high flux (Cr=7.1, Sc=23.1) of low-energy (9 eV) Ar ions yielded the most favorable growth condition, limiting the intermixing with a subsistent good surface flatness.
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| 23. |
- Esmaeildoost, Niloofar
(författare)
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Optical and x-ray studies of ice growth in water
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The key purpose of this thesis is to study the structure of metastable water and its transformation into ice upon deep supercooling using x-ray scattering as well as optical microscopy. In all experiments, micrometer-sized water droplets were evaporatively cooled in vacuum and probed either by x-rays or optical illumination. In addition to these, an infrared (IR) heating pulse was employed in one of the experiments to introduce a temperature jump in water droplets and achieve ultrafast calorimetry, which can measure specific heat capacity upon supercooling. The second peak of the structure factor presented a maximum at 236 K. The anomalous decrease in peak positions below 236 K was related to a repeat spacing in the tetrahedral network, associated with the intermediaterange correlations in water. The decrease in temperature makes the paircorrelation function change in a similar manner to that of low-density amorphous ice (LDA), meaning that the structure moves towards a less dense local ordering. This is in consistency with a low-density pentamer-bonded tetrahedral network that shifts continuously towards an LDA structure as it cools down. The x-ray scattering data showed that there is a maximum in the specific heat capacity of water at about 229 K and it increases from 88 J/mol/K at 244 K to 218 J/mol/K at 229 K upon cooling. Homogeneous ice nucleation showed that there is a mechanism of freezing based on the rates at which different frozen stages, i.e., partially frozen, liquid extrusion and fractured droplets, are seen in the microscopic images. Experimental nucleation data at temperatures as low as ∼230 K resulted in a nucleation fitting curve that shows a slower nucleation rate increase upon supercooling. Using self-diffusion data that was experimentally measured through wide-angle x-ray scattering and ultrafast calorimetry, we can assess the interfacial energy as a function of temperature. This resulted in a minimum in interfacial energy at around 236 K. Moreover, within the droplet, ice tends to form different structures after it has nucleated based on where in the droplet it is growing. It was observed that for crystals inside the bulk and close to the center of the droplets, ice crystallizes with hexagonal structure whereas on the surface it crystallizes with stacking-disorder containing a considerable amount of cubic structure. This can come from the fact that planar growth of crystals at the surface breaks down into a faulty structure that needs to accommodate the curvature of the droplet’s surface.
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| 24. |
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| 25. |
- Fogelqvist, Emelie, et al.
(författare)
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Laboratory cryo x-ray microscopy for 3D cell imaging
- 2017
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Water-window x-ray microscopy allows two-and three-dimensional (2D and 3D) imaging of intact unstained cells in their cryofixed near-native state with unique contrast and high resolution. Present operational biological water-window microscopes are based at synchrotron facilities, which limits their accessibility and integration with complementary methods. Laboratory-source microscopes have had difficulty addressing relevant biological tasks with proper resolution and contrast due to long exposure times and limited up-time. Here we report on laboratory cryo x-ray microscopy with the exposure time, contrast, and reliability to allow for routine high-spatial resolution 3D imaging of intact cells and cell-cell interactions. Stabilization of the laser-plasma source combined with new optics and sample preparation provide high-resolution cell imaging, both in 2D with ten-second exposures and in 3D with twenty-minute tomography. Examples include monitoring of the distribution of carbon-dense vesicles in starving HEK293T cells and imaging the interaction between natural killer cells and target cells.
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| 26. |
- Fogelqvist, Emelie, 1988-
(författare)
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Laboratory Soft X-Ray Cryo Microscopy: Source, System and Bio Applications
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Soft x-ray microscopes routinely perform high-resolution 3D imaging of biological cells in their near-native environment with short exposure times at synchrotron radiation facilities. Some laboratory-sized microscopes are aiming to make this imaging technique more accessible to a wider scientific community. However, these systems have been hampered by source instabilities hindering routine imaging of biological samples with short exposure times.This Thesis presents work performed on the Stockholm laboratory x-ray microscope. A novel heat control system has been implemented, improving the stability of the laser-produced plasma source. In combination with recent upgrades to the imaging system and an improved cryofixation method, the microscope now has the capability to routinely produce images with 10-second exposure time of cryofixed biological samples. This has allowed for tomographic imaging of cell autophagy and cell-cell interactions. Furthermore, a numerical 3D image formation model is presented as well as a novel reconstruction approach dealing with the limited depth of focus in x-ray microscopes.
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| 27. |
- Fogelqvist, Emelie, et al.
(författare)
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Stability of liquid-nitrogen-jet laser-plasma targets
- 2015
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 118:17
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Tidskriftsartikel (refereegranskat)abstract
- Microscopic jets of cryogenic substances such as liquid nitrogen are important regenerative high-density targets for high-repetition rate, high-brightness laser-plasma soft x-ray sources. When operated in vacuum such liquid jets exhibit several non-classical instabilities that negatively influence the x-ray source's spatial and temporal stability, yield, and brightness, parameters that all are important for applications such as water-window microscopy. In the present paper, we investigate liquid-nitrogen jets with a flash-illumination imaging system that allows for a quantitative stability analysis with high spatial and temporal resolution. Direct and indirect consequences of evaporation are identified as the key reasons for the observed instabilities. Operating the jets in an approximately 100 mbar ambient atmosphere counteracts the effects of evaporation and produces highly stable liquid nitrogen jets. For operation in vacuum, which is necessary for the laser plasmas, we improve the stability by introducing an external radiative heating element. The method significantly extends the distance from the nozzle that can be used for liquid-jet laser plasmas, which is of importance for high-average-power applications. Finally, we show that laser-plasma operation with the heating-element-stabilized jet shows improved short-term and long-term temporal stability in its water-window x-ray emission.
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| 28. |
- Fogelqvist, Emelie, et al.
(författare)
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The Stockholm laboratory cryo x-ray microscope : towards cell-cell interaction studies
- 2013
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Ingår i: 11th International Conference On X-Ray Microscopy (XRM2012). - : Institute of Physics (IOP). ; , s. 012054-
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Konferensbidrag (refereegranskat)abstract
- We describe recent improvements in the Stockholm laboratory x-ray microscope and the first experiments aiming towards studies of cell-cell interaction. The shorter exposure time due to a higher brightness laser-plasma source will become of large importance for tomography while the reproducible cryo preparation of few-cell samples is essential for the interaction studies.
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| 29. |
- Gleber, S. -C, et al.
(författare)
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X-ray stereo microscopy for investigation of dynamics in soils
- 2009
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 186, s. 012104-
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Tidskriftsartikel (refereegranskat)abstract
- The here presented combination of stereo imaging and elemental mapping with soft X-ray microscopy reveals the spatial arrangement of naturally aqueous colloidal systems, e.g. iron oxides in soil colloid clusters. Changes in the spatial arrangement can be induced by manipulating the sample in-situ and thus be investigated directly and as a function of time.
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| 30. |
- Granholm, Anders, et al.
(författare)
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Empirical meropenem versus piperacillin/tazobactam for adult patients with sepsis (EMPRESS) trial : Protocol
-
Ingår i: Acta Anaesthesiologica Scandinavica. - 0001-5172.
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Piperacillin/tazobactam may be associated with less favourable outcomes than carbapenems in patients with severe bacterial infections, but the certainty of evidence is low. Methods: The Empirical Meropenem versus Piperacillin/Tazobactam for Adult Patients with Sepsis (EMPRESS) trial is an investigator-initiated, international, parallel-group, randomised, open-label, adaptive clinical trial with an integrated feasibility phase. We will randomise adult, critically ill patients with sepsis to empirical treatment with meropenem or piperacillin/tazobactam for up to 30 days. The primary outcome is 30-day all-cause mortality. The secondary outcomes are serious adverse reactions within 30 days; isolation precautions due to resistant bacteria within 30 days; days alive without life support and days alive and out of hospital within 30 and 90 days; 90- and 180-day all-cause mortality and 180-day health-related quality of life. EMPRESS will use Bayesian statistical models with weak to somewhat sceptical neutral priors. Adaptive analyses will be conducted after follow-up of the primary outcome for the first 400 participants concludes and after every 300 subsequent participants, with adaptive stopping for superiority/inferiority and practical equivalence (absolute risk difference <2.5%-points) and response-adaptive randomisation. The expected sample sizes in scenarios with no, small or large differences are 5189, 5859 and 2570 participants, with maximum 14,000 participants and ≥99% probability of conclusiveness across all scenarios. Conclusions: EMPRESS will compare the effects of empirical meropenem against piperacillin/tazobactam in adult, critically ill patients with sepsis. Due to the pragmatic, adaptive design with high probability of conclusiveness, the trial results are expected to directly inform clinical practice.
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| 31. |
- Hansson, B. A. M., et al.
(författare)
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A liquid-xenon-jet laser-plasma X-ray and EUV source
- 2000
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Ingår i: Microelectronic Engineering. - 0167-9317 .- 1873-5568. ; 53:04-jan, s. 667-670
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Tidskriftsartikel (refereegranskat)abstract
- We describe a laser-plasma soft-x-ray source based on a cryogenic-xenon liquid-jet target. The source is suitable for extreme ultraviolet (EUV) projection lithography and proximity x-ray lithography (PXL). Absolute calibrated spectra in the 1-2 nm range and uncalibrated spectra in the 9-15 nm range are obtained using a free-standing transmission grating and a CCD-detector.
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| 32. |
- Hansson, B. A. M., et al.
(författare)
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Characterisation of a liquid-xenon jet laser-plasma extreme-ultraviolet source
- 2004
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 75:6, s. 2122-2129
-
Tidskriftsartikel (refereegranskat)abstract
- A liquid-xenon-jet laser-plasma source for extreme-ultraviolet (EUV) and soft-x-ray generation has been characterized. Being a source candidate for EUV lithography (EUVL), we especially focus on parameters important for the integration of the source in EUVL systems. The deep-ultraviolet (DUV) out-of-band radiation (=120–400 nm) was quantified, to within a factor of two, using a flying-circus tool together with a transmission-grating spectrograph resulting in a total DUV conversion efficiency (CE) of ~0.33%/2sr. The size and the shape of the xenon plasma was investigated using an in-band-only EUV microscope, based on a spherical Mo/Si multilayer mirror and a charge-coupled device detector. Scalability of the source size from 20–270 µm full width at half maximum was shown. The maximum repetition-rate sustainable by the liquid-xenon-jet target was simulated by a double-pulse experiment indicating feasibility of >17 kHz operation. The xenon-ion energy distribution from the plasma was determined in a time-of-flight experiment with a Faraday-cup detector showing the presence of multi-kilo-electron-volt ions. Sputtering of silicon witness plates exposed to the plasma was observed, while a xenon background of >1 mbar was shown to eliminate the sputtering. It is concluded that the source has potential to meet the requirements of future EUVL systems.
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| 33. |
- Hansson, Björn A. M., et al.
(författare)
-
Improved emission uniformity from a liquid-jet laser-plasma extreme-ultraviolet source
- 2004
-
Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 43:29, s. 5452-5457
-
Tidskriftsartikel (refereegranskat)abstract
- Many modern compact soft-x-ray and extreme-ultraviolet (EUV) imaging systems operate with small fields of view and therefore benefit from the use of small high-brightness sources. Such systems include water-window microscopes and ELTV lithography tools. We show that the photon losses in such systems can be minimized while uniformity of object-plane illumination is maintained by controlled scanning of the source. The improved collection efficiency is demonstrated both theoretically and experimentally for a scanned laser-plasma source compared with static sources. A prospective aerial image microscope and a liquid-xenon-jet laser-plasma source are offered as examples of modem imaging tools that may benefit from such scanning of the source.
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| 34. |
- Hansson, B. A. M., et al.
(författare)
-
Liquid-jet laser-plasma extreme ultraviolet sources : from droplets to filaments
- 2004
-
Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 37:23, s. 3233-3243
-
Tidskriftsartikel (refereegranskat)abstract
- The laser plasma is one of the major contenders as a high-power source for future high-volume-manufacturing extreme ultraviolet lithography systems. Such laser-plasma sources require a target system that allows high-repetition-rate operation with low debris and manageable thermal load at the required high laser power. In this paper, we review the development of the liquid-jet target laser plasmas, from droplets to filaments, with special emphasis on its applicability for high-power extreme ultraviolet generation. We focus on two target systems, the liquid-xenon-jet and the liquid-tin-jet.
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| 35. |
- Hansson, B. A. M., et al.
(författare)
-
Liquid-xenon-jet LPP source
- 2006
-
Ingår i: EUV Sources for Lithography. - : SPIE - International Society for Optical Engineering. - 9780819480712 ; , s. 619-647
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 36. |
- Hansson, Björn, et al.
(författare)
-
Stabilization of liquified-inert-gas jets for laser-plasma generation
- 2004
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 95:8, s. 4432-4437
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the hydrodynamic properties of liquified-inert-gas jets in a vacuum with a special emphasis on their stability. Such jets have applications as targets for laser-plasma generation of soft-x-ray and extreme-ultraviolet (EUV) radiation. An important example is the liquid-xenon-jet laser-plasma source, one of the source candidates for EUV lithography. A simple hydrodynamic model in not sufficient to explain experimental observations of jet stability. Evaporation-induced cooling explains observed in-flight freezing of the jet and may be a key factor influencing jet stability. It is shown how the jet stability, and, thus, the stability of the laser-plasma x-ray and EUV emission, are improved by applying localized heating to the tip of the jet-generating nozzle.
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| 37. |
- Hemberg, Oskar, et al.
(författare)
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A Liquid-Metal-Jet Anode X-Ray Tube
- 2004
-
Ingår i: Optical Engineering. - : SPIE-Intl Soc Optical Eng. - 0091-3286 .- 1560-2303. ; 43:7, s. 1682-1688
-
Tidskriftsartikel (refereegranskat)abstract
- We describe a novel electron-impact x-ray source based on a high-speed liquid-metal-jet anode. Thermal power load calculations indicate that this new anode concept potentially could increase the achievable brightness in compact electron-impact x-ray sources by more than a factor 100 compared to current state-of-the-art rotating-anode or microfocus sources. A first, successful, low-power proof-of-principle experiment is described and the feasibility of scaling to high-brightness and high-power operation is discussed. Some possible applications that would benefit from such an increase in brightness are also briefly
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| 38. |
- Hemberg, Oscar, et al.
(författare)
-
High-brightness liquid-metal-jet x-ray tube
- 2011
-
Ingår i: Acta Crystallographica Section A. - : International Union of Crystallography. - 2053-2733. ; 67, s. C257-C257
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 39. |
- Hemberg, Oscar, et al.
(författare)
-
Liquid-Metal-Jet Anode Electron-Impact X-Ray Source
- 2003
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 83, s. 1483-1485
-
Tidskriftsartikel (refereegranskat)abstract
- A liquid-metal-jet anode for improved brightness in compact electron-impact x-ray source was investigated. The generated x-ray flux and brightness was quantitatively measured in the 7-50 keV spectral region and found to agree with the theory. Applications such as mammography, angiography, and diffraction would benefit from a compact high-brightness source.
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| 40. |
- Hemberg, O., et al.
(författare)
-
Stability of droplet-target laser-plasma soft x-ray sources
- 2000
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 88:9, s. 5421-5425
-
Tidskriftsartikel (refereegranskat)abstract
- The spatial stability of microscopic target droplets used for laser-plasma soft x-ray generation in vacuum is investigated. A long-term drift in drop position is characterized with an ultrafast laser-diode imaging system. The drift is experimentally and theoretically shown to be due to a temperature-induced increase in target-liquid viscosity as a result of evaporation. Finally, the drift is compensated for and stable, long-term unattended operation of the source is demonstrated with an automatic phase-delay drop-to-laser synchronizing system. This is important for future compact lithography and microscopy systems.
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| 41. |
- Hemberg, Oscar, et al.
(författare)
-
The liquid-metal-jet anode x-ray source
- 2004
-
Ingår i: Proceedings of The International Society for Optical Engineering. - : SPIE. ; , s. 421-431
-
Konferensbidrag (refereegranskat)abstract
- We introduce a novel electron-impact x-ray source based on a high-speed liquid-metal-jet anode. Basic thermal power load calculations indicate that this new anode concept potentially could increase the achievable brightness in compact electron-impact x-ray sources by more than a factor 100 compared to current state-of-the-art rotating-anode or microfocus sources. A first, successful, low-power proof-of-principle experiment is described and the feasibility of scaling to high-brightness and high-power operation is discussed. Some possible applications that would benefit from such an increase in brightness are also briefly described.
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| 42. |
- Hertz, Birgit, et al.
(författare)
-
Nematophagous Fungi
- 2000
-
Ingår i: Encyclopedia of Life Science (ELS). - 047001590X
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Abstract is not available
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| 43. |
|
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| 44. |
- Hertz, Hans, et al.
(författare)
-
Laboratory cryo soft X-ray microscopy
- 2012
-
Ingår i: Journal of Structural Biology. - : Elsevier. - 1047-8477 .- 1095-8657. ; 177:2, s. 267-272
-
Tidskriftsartikel (refereegranskat)abstract
- Lens-based water-window X-ray microscopy allows two- and three-dimensional (2D and 3D) imaging of intact unstained cells in their near-native state with unprecedented contrast and resolution. Cryofixation is essential to avoid radiation damage to the sample. Present cryo X-ray microscopes rely on synchrotron radiation sources, thereby limiting the accessibility for a wider community of biologists. In the present paper we demonstrate water-window cryo X-ray microscopy with a laboratory-source-based arrangement. The microscope relies on a lambda = 2.48-nm liquid-jet high-brightness laser-plasma source, normal-incidence multilayer condenser optics, 30-nm zone-plate optics, and a cryo sample chamber. We demonstrate 2D imaging of test patterns, and intact unstained yeast, protozoan parasites and mammalian cells. Overview 3D information is obtained by stereo imaging while complete 3D microscopy is provided by full tomographic reconstruction. The laboratory microscope image quality approaches that of the synchrotron microscopes, but with longer exposure times. The experimental image quality is analyzed from a numerical wave-propagation model of the imaging system and a path to reach synchrotron-like exposure times in laboratory microscopy is outlined.
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| 45. |
- Hertz, Hans, et al.
(författare)
-
Laboratory Water-Window X-Ray Microscopy
- 2009
-
Ingår i: 2009 IEEE LEOS ANNUAL MEETING CONFERENCE PROCEEDINGS. - 9781424436804 ; , s. 48-48
-
Konferensbidrag (refereegranskat)abstract
- We review recent progress in laboratory water-window microscopy including 250 W/0.8 ns/2 kHz laser-plasma liquid-jet sources, 13-nm zone width diffractive optics, diffractive optical elements for phase-contrast microscopy, <25-nm resolution microscopy using compound zone plates, tomography and applications in soil science.
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| 46. |
- Hertz, Hans M., et al.
(författare)
-
Electron-Impact Liquid-Metal-Jet Hard x-Ray Sources
- 2014
-
Ingår i: Comprehensive Biomedical Physics. - : Elsevier. - 9780444536327 ; , s. 91-109
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The power and brightness of electron-impact microfocus x-ray sources have long been limited by thermal damage in the target. This is a major constraint for a wide range of biomedical applications, from imaging to diffraction. Here, we describe the development of an x-ray microfocus source based on a new target concept, the liquid-metal jet (LMJ). The regenerative nature of this target allows for significantly higher e-beam power density than on conventional targets, resulting in this source showing promise for >. 100. × higher brightness than state-of-the-art sources. We first discuss the basic physics of the two important subsystems of the source, LMJ in vacuum and focused electron-beam systems, and then describe the properties of several versions of the source, from early prototypes to the first LMJ sources now reaching the market. Finally, we review some early applications of the source for biomedical imaging and diffraction.
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| 47. |
- Hertz, Hans M., et al.
(författare)
-
Laboratory x-ray fluorescence tomography for high-resolution nanoparticle bio-imaging
- 2014
-
Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 39:9, s. 2790-2793
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that nanoparticle x-ray fluorescence computed tomography in mouse-sized objects can be performed with very high spatial resolution at acceptable dose and exposure times with a compact laboratory system. The method relies on the combination of the 24 keV line-emission from a high-brightness liquid-metal-jet x-ray source, pencil-beam-forming x-ray optics, photon-counting energy-dispersive detection, and carefully matched (Mo) nanoparticles. Phantom experiments and simulations show that the arrangement significantly reduces Compton background and allows 100 mu m detail imaging at dose and exposure times compatible with small-animal experiments. The method provides a possible path to in vivo molecular x-ray imaging at sub-100 mu m resolution in mice.
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| 48. |
- Hertz, Hans M., et al.
(författare)
-
Laboratory X-ray micro- and nano-imaging
- 2009
-
Ingår i: Frontiers in Optics (FiO) 2009. - Washington, D.C. : Optical Society of America. - 9781557528780
-
Konferensbidrag (refereegranskat)abstract
- We summarize recent progress in laboratory x-ray imaging systems based on compact high-brightness liquid-jet sources, including <25 nm soft x-ray zone-plate microscopy and <10 μm (lens-free) hard x-ray phase-contrast imaging.
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| 49. |
- Hertz, Hans M., et al.
(författare)
-
Laboratory x-ray micro imaging : Sources, optics, systems and applications
- 2009
-
Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 186
-
Tidskriftsartikel (refereegranskat)abstract
- We summarize the recent progress in laboratory-scale soft and hard x-ray micro imaging in Stockholm. Our soft x-ray work is based on liquid-jet laser-plasma sources which are combined with diffractive and multilayer optics to form laboratory x-ray microscopes. In the hard x-ray regime the imaging is based on a liquid-metal-jet electron-impact source which provides the necessary coherence to allow phase-contrast imaging with high fidelity.
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| 50. |
- Hertz, Hans M., et al.
(författare)
-
Laboratory X-ray microscopy for high-resolution imaging of environmental colloid structure
- 2012
-
Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 329:SI, s. 26-31
-
Tidskriftsartikel (refereegranskat)abstract
- Transmission X-ray microscopy is a uniquely suited technique for studies of environmental colloids since it allows imaging in aqueous media with high spatial resolution, presently down to the 20 nm range. Such nanoscale morphological description of these high-specific-surface-area compounds show promise for improved understanding of soils, sediments or groundwater aquifers. However, present high-quality X-ray microscopes are located at synchrotron radiation facilities resulting in limited applicability and accessibility for colloid scientists. Here we investigate the applicability of a laboratory-scale transmission X-ray microscope for studies of colloids of the environment. The microscope is based on a laser-plasma source in combination with multilayer and zone plate optics. Samples are held at atmospheric pressure in their natural wet state. We show images revealing the nano-scale morphology of the clay nontronite, soils such as chernozem and luvisol, and the mineral hematite, an iron oxide. Comparative studies of dried substances clearly show the need for imaging in the wet state. The image quality approaches that of synchrotron-based microscopes, albeit at longer exposure times. Stereo imaging is investigated as a means for giving 3D information with shorter exposure times than tomography requires. Finally the future development of the laboratory X-ray microscope is discussed, especially with regard to the reduction of exposure times.
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