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  • 151.
    Lindblom, Magnus
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Tuohimaa, Tomi
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Holmberg, Anders
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Wilhein, Thomas
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Ulrich
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    High-resolution differential-interference-contrast x-ray zone plates: Design and Fabrication2007Ingår i: Spectrochimica Acta Part B - Atomic Spectroscopy, ISSN 0584-8547, E-ISSN 1873-3565, Vol. 62, nr 6-7, s. 539-543Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Differential interference contrast is a potentially powerful technique for contrast enhancement in soft X-ray microscopy. We describe the design and fabrication of single-element diffractive optical elements suitable as objectives for high-resolution differential interference contrast microscopy in the water-window spectral range. A one-dimensional pattern calculation followed by an extension to two dimensions results in a pattern resolution of 1 nm, which is well below fabrication accuracy. The same fabrication process as for normal zone plates is applicable, but special care must be taken when converting the calculated pattern to a code for e-beam lithography.

  • 152. Lindskoog Pettersson, Anna
    et al.
    Jarkö, Caroline
    Alvin, Åsa
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Brautaset, Rune
    Spherical aberration in contact lens wear2008Ingår i: Contact lens & anterior eye, ISSN 1367-0484, E-ISSN 1476-5411, Vol. 31, nr 4, s. 189-193Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Introduction: The aim of the present studies was to investigate the effect on spherical aberration of different non custom-made contact lenses, both with and without aberration control. Methods: A wavefront analyser (Zywave™, Bausch & Lomb) was used to measure the aberrations in each subject's right eye uncorrected and with the different contact lenses. The first study evaluated residual spherical aberration with a standard lens (Focus Dailies Disposable, Ciba Vision) and with an aberration controlled contact lens (ACCL) (Definition AC, Optical Connection Inc.). The second study evaluated the residual spherical aberrations with a monthly disposable silicone hydrogel lens with aberration reduction (PureVision, Bausch & Lomb). Results: Uncorrected spherical aberration was positive for all pupil sizes in both studies. In the first study, residual spherical aberration was close to zero with the standard lens for all pupil sizes whereas the ACCL over-corrected spherical aberration. The results of the second study showed that the monthly disposable lens also over-corrected the aberration making it negative. The changes in aberration were statistically significant (p < 0.05) with all lenses. Conclusion: Since the amount of aberration varies individually we suggest that aberrations should be measured with lenses on the eye if the aim is to change spherical aberration in a certain direction.

  • 153.
    Lobov, G. S.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Marinins, A.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Etcheverry, S.
    Zhao, Yichen
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Vasileva, Elena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Sugunan, A.
    Laurell, F.
    Thylén, Lars
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Wosinski, L.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Toprak, M. S.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Direct birefringence and transmission modulation via dynamic alignment of P3HT nanofibers in an advanced opto-fluidic component2017Ingår i: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 7, nr 1, s. 52-61Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly-3-hexylthiophene (P3HT) nanofibers are semiconducting high-aspect ratio nanostructures with anisotropic absorption and birefringence properties found at different regions of the optical spectrum. In addition, P3HT nanofibers possess an ability to be aligned by an external electric field, while being dispersed in a liquid. In this manuscript we show that such collective ordering of nanofibers, similar to liquid crystal material, significantly changes the properties of transmitted light. With a specially fabricated opto-fluidic component, we monitored the phase and transmission modulation of light propagating through the solution of P3HT nanofibers, being placed in the electric field with strength up to 0.1 V/μm. This report describes a technique for light modulation, which can be implemented in optical fiber-based devices or on-chip integrated components.

  • 154.
    Lundholm, Ida V.
    et al.
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Sellberg, Jonas A.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Ekeberg, Tomas
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Hantke, Max F.
    Univ Oxford, Oxford, England..
    Okamoto, Kenta
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    van der Schot, Gijs
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Andreasson, Jakob
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden.;Czech Acad Sci, Inst Phys, ELI Beamlines, Slovance 2, CZ-18221 Prague, Czech Republic.;Chalmers Univ Technol, Dept Phys, Condensed Matter Phys, Gothenburg, Sweden..
    Barty, Anton
    DESY, Ctr Free Electron Laser Sci, Notkestr 85, D-22607 Hamburg, Germany..
    Bielecki, Johan
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden.;European XFEL GmbH, Holzkoppel 4, D-22869 Schenefeld, Germany..
    Bruza, Petr
    Chalmers Univ Technol, Dept Phys, Condensed Matter Phys, Gothenburg, Sweden..
    Bucher, Max
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Stanford, CA 94309 USA.;Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany.;Argonne Natl Lab, Chem Sci & Engn Div, 9700 South Cass Ave, Lemont, IL 60439 USA..
    Carron, Sebastian
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Stanford, CA 94309 USA..
    Daurer, Benedikt J.
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Ferguson, Ken
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Stanford, CA 94309 USA.;PULSE Inst, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.;SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA..
    Hasse, Dirk
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Krzywinski, Jacek
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Stanford, CA 94309 USA..
    Larsson, Daniel S. D.
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Morgan, Andrew
    DESY, Ctr Free Electron Laser Sci, Notkestr 85, D-22607 Hamburg, Germany..
    Muhlig, Kerstin
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Mueller, Maria
    Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany..
    Nettelblad, Carl
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden.;Uppsala Univ, Dept Informat Technol, Sci Life Lab, Div Sci Comp, Lagerhyddsvagen 2,Box 337, SE-75105 Uppsala, Sweden..
    Pietrini, Alberto
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Reddy, Hemanth K. N.
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Rupp, Daniela
    Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany..
    Sauppe, Mario
    Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany..
    Seibert, Marvin
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Svenda, Martin
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Swiggers, Michelle
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Stanford, CA 94309 USA..
    Timneanu, Nicusor
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden.;Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden..
    Ulmer, Anatoli
    Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany..
    Westphal, Daniel
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Williams, Garth
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Stanford, CA 94309 USA.;Brookhaven Natl Lab, NSLS 2, POB 5000, Upton, NY 11973 USA..
    Zani, Alessandro
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden..
    Faigel, Gyula
    Res Inst Solid State Phys & Opt, H-1525 Budapest, Hungary..
    Chapman, Henry N.
    DESY, Ctr Free Electron Laser Sci, Notkestr 85, D-22607 Hamburg, Germany..
    Moeller, Thomas
    Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany..
    Bostedt, Christoph
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Stanford, CA 94309 USA.;Argonne Natl Lab, Chem Sci & Engn Div, 9700 South Cass Ave, Lemont, IL 60439 USA.;PULSE Inst, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.;SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.;Northwestern Univ, Dept Phys, 2145 Sheridan Rd, Evanston, IL 60208 USA..
    Hajdu, Janos
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden.;Czech Acad Sci, Inst Phys, ELI Beamlines, Slovance 2, CZ-18221 Prague, Czech Republic..
    Gorkhover, Tais
    Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany.;PULSE Inst, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA.;SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA..
    Maia, Filipe R. N. C.
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden.;Lawrence Berkeley Natl Lab, NERSC, 1 Cyclotron Rd, Berkeley, CA 94720 USA..
    Considerations for three-dimensional image reconstruction from experimental data in coherent diffractive imaging2018Ingår i: IUCrJ, ISSN 0972-6918, E-ISSN 2052-2525, Vol. 5, s. 531-541Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Diffraction before destruction using X-ray free-electron lasers (XFELs) has the potential to determine radiation-damage-free structures without the need for crystallization. This article presents the three-dimensional reconstruction of the Melbournevirus from single-particle X-ray diffraction patterns collected at the LINAC Coherent Light Source (LCLS) as well as reconstructions from simulated data exploring the consequences of different kinds of experimental sources of noise. The reconstruction from experimental data suffers from a strong artifact in the center of the particle. This could be reproduced with simulated data by adding experimental background to the diffraction patterns. In those simulations, the relative density of the artifact increases linearly with background strength. This suggests that the artifact originates from the Fourier transform of the relatively flat background, concentrating all power in a central feature of limited extent. We support these findings by significantly reducing the artifact through background removal before the phase-retrieval step. Large amounts of blurring in the diffraction patterns were also found to introduce diffuse artifacts, which could easily be mistaken as biologically relevant features. Other sources of noise such as sample heterogeneity and variation of pulse energy did not significantly degrade the quality of the reconstructions. Larger data volumes, made possible by the recent inauguration of high repetition-rate XFELs, allow for increased signal-to-background ratio and provide a way to minimize these artifacts. The anticipated development of three-dimensional Fourier-volume-assembly algorithms which are background aware is an alternative and complementary solution, which maximizes the use of data.

  • 155.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Gustafsson, Jörgen
    Rehabilitation Engineering Research, Department of Design Science, Lund University.
    Svensson, Ingrid
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Assessment of objective and subjective eccentric refraction2005Ingår i: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 82, nr 4, s. 298-306Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose. When performing perimetry, refracting subjects with central visual field loss, and in emmetropization studies, it is important to accurately measure peripheral refractive errors. Traditional methods for foveal refraction often give uncertain results in eccentric angles as a result of the large aberrations and the reduced retinal function. The aim of this study is therefore to compare and evaluate four methods for eccentric refraction. Methods. Four eccentric methods were tested on 50 healthy subjects: one novel subjective procedure, optimizing the detection contrast sensitivity with different trial lenses, and three objective ones: photorefraction with a PowerRefractor, wavefront measurements with a Hartmann-Shack sensor, and retinoscopy. The peripheral refractive error in the horizontal nasal visual field of the right eye was measured in 20 degrees and 30 degrees. Results. In general, the eccentric refraction methods compared reasonably well. However, the following differences were noted. Retinoscopy showed a significant difference from the other methods in the axis of astigmatism. In 300 eccentric angle, it was not possible to measure 15 of the subjects with the PowerRefractor and the instrument also tended to underestimate high myopia (<-6 D). The Hartmann-Shack sensor showed a myopic shift of approximately 0.5 D in both eccentricities. The subjective method had a relatively larger spread. Conclusions. This study indicates that it is possible to assess the eccentric refraction with all methods. However, the Hartmann-Shack technique was found to be the most useful method. The agreement between the objective methods and the subjective eccentric refraction shows that detection contrast sensitivity in the periphery is affected by relatively small amounts of defocus.

  • 156.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Gustafsson, Jörgen
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Population distribution of wavefront aberrations in the peripheral human eye2009Ingår i: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 26, nr 10, s. 2192-2198Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a population study of peripheral wavefront aberrations in large off-axis angles in terms of Zernike coefficients. A laboratory Hartmann-Shack sensor was used to assess the aberrations in 0 degrees, 20 degrees, and 30 degrees in the nasal visual field of 43 normal eyes. The elliptical pupil meant that the quantification could be done in different ways. The three approaches used were (1) over a circular aperture encircling the pupil, (2) over a stretched version of the elliptical pupil, and (3) over a circular aperture within the pupil (MATLAB conversion code given). Astigmatism (c(2)(2)) increased quadratically and coma (c(3)(1)) linearly with the horizontal viewing angle, whereas spherical aberration (c(4)(0)) decreased slightly toward the periphery. There was no correlation between defocus and angle, although some trends were found when the subjects were divided into groups depending on refractive error. When comparing results of different studies it has to be kept in mind that the coefficients differ depending on how the elliptical pupil is taken into consideration.

  • 157.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Gustafsson, Jörgen
    Vision Enabling Laboratory, School of Optometry, Kalmar University.
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vision evaluation of eccentric refractive correction2007Ingår i: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 84, nr 11, s. 1046-1052Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose. This study investigates the benefits of eccentric refractive correction to resolution and detection thresholds in different contrasts for seven subjects with central visual field loss (CFL) and for four healthy control subjects with normal vision.

    Methods. Refractive correction in eccentric viewing angles, i.e., the preferred retinal location for the CFL subjects and 20 degrees off-axis for the control subjects, was assessed by photorefraction with the PowerRefractor instrument and by wavefront analysis using the Hartmann-Shack principle. The visual function with both eccentric and central corrections was evaluated using number identification and grating detection.

    Results. For the CFL subjects, the resolution and detection thresholds varied between individuals because of different preferred retinal locations and cause of visual field loss. However, all seven CFL subjects showed improved visual function for resolution and detection tasks with eccentric correction compared with central correction. No improvements in high-contrast resolution were found for the control subjects.

    Conclusions. These results imply that optical eccentric correction can improve the resolution acuity for subjects with CFL in situations where healthy eyes do not show any improvements.

  • 158.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Manzanera, Silvestre
    Laboratorio de Optica, Universidad de Murcia.
    Prieto, Pedro
    Laboratorio de Optica, Universidad de Murcia.
    Ayala, Diego
    Laboratorio de Optica, Universidad de Murcia.
    Gorceix, Nicolas
    Laboratorio de Optica, Universidad de Murcia.
    Gustafsson, Jörgen
    School of Optometry, Kalmar University.
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Artal, Pablo
    Laboratorio de Optica, Universidad de Murcia.
    Effect of optical correction and remaining aberrations on peripheral resolution acuity in the human eye2007Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 15, nr 20, s. 12654-12661Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Retinal sampling poses a fundamental limit to resolution acuity in the periphery. However, reduced image quality from optical aberrations may also influence peripheral resolution. In this study, we investigate the impact of different degrees of optical correction on acuity in the periphery. We used an adaptive optics system to measure and modify the off-axis aberrations of the right eye of six normal subjects at 20 degrees eccentricity. The system consists of a Hartmann-Shack sensor, a deformable mirror, and a channel for visual testing. Four different optical corrections were tested, ranging from foveal sphero-cylindrical correction to full correction of eccentric low- and high-order monochromatic aberrations. High-contrast visual acuity was measured in green light using a forced choice procedure with Landolt C's, viewed via the deformable mirror through a 4.8-mm artificial pupil. The Zernike terms mainly induced by eccentricity were defocus and with- and against-the-rule astigmatism and each correction condition was successfully implemented. On average, resolution decimal visual acuity improved from 0.057 to 0.061 as the total root-mean-square wavefront error changed from 1.01 mu m to 0.05 mu m. However, this small tendency of improvement in visual acuity with correction was not significant. The results suggest that for our experimental conditions and subjects, the resolution acuity in the periphery cannot be improved with optical correction.

  • 159.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Rosen, Robert
    Abbott Med Opt Groningen BV, Appl Res, Groningen, Netherlands..
    Van der Mooren, Marrie
    Abbott Med Opt Groningen BV, Appl Res, Groningen, Netherlands..
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Piers, Patricia A.
    Abbott Med Opt Groningen BV, Appl Res, Groningen, Netherlands..
    Low Amounts of Scattering Reduce Central as well as Peripheral Contrast Sensitivity2014Ingår i: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 55, nr 13Artikel i tidskrift (Övrigt vetenskapligt)
  • 160.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Rosén, R.
    Peripheral aberrations2017Ingår i: Handbook of Visual Optics, Volume One: Fundamentals and Eye Optics, CRC Press , 2017, s. 313-335Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    The schematic of Figure 21.1 is highly simplified, assuming spherical and aligned surfaces. Nevertheless, it demonstrates two important facts regarding the optical errors of the human eye: that the blur increases with the off-axis angle to the object and that it depends on the size of the pupil. For instance, spherical aberration has a cubic dependence on pupil size and coma has a quadratic dependence, whereas TCA is independent. To exemplify, Figure 21.2 shows the variation in monochromatic image quality over the visual field measured for one subject. The following paragraphs will briefly explain the origin of the four largest peripheral aberrations, namely, astigmatism, field curvature, coma, and TCA. © 2017 by Taylor & Francis Group, LLC.

  • 161.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Rosén, Robert
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Baskaran, K.
    Jaeken, B.
    Gustafsson, J.
    Artal, P.
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Symmetries in peripheral ocular aberrations2011Ingår i: Journal of Modern Optics, ISSN 0950-0340, E-ISSN 1362-3044, Vol. 58, nr 19-20, s. 1690-1695Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A mirror symmetry in the aberrations between the left and right eyes has previously been found foveally, but while a similar symmetry for the peripheral visual field is likely, it has not been investigated. Nevertheless, the peripheral optical quality is often evaluated in only one eye, because it is more time efficient than analyzing the whole visual field of both eyes. This study investigates the correctness of such an approach by measuring the peripheral wavefront aberrations in both eyes of 22 subjects out to +/- 40 degrees horizontally. The largest aberrations (defocus, astigmatism, and coma) were found to be significantly correlated between the left and right eyes when comparing the same temporal or nasal angle. The slope of the regression line was close to +/- 1 (within 0.05) for these aberrations, with a negative slope for the horizontally odd aberrations, i.e. the left and right eyes are mirror symmetric. These findings justify that the average result, sampled in one of the two eyes of many subjects, can be generalized to the other eye as well.

  • 162.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Transformation of Zernike coefficients: scaled, translated, and rotated wavefronts with circular and elliptical pupils2007Ingår i: Journal of the Optical Society of America A, ISSN 0740-3232, Vol. 24, nr 3, s. 569-577Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Zernike polynomials and their associated coefficients are commonly used to quantify the wavefront aberrations of the eye. When the aberrations of different eyes, pupil sizes, or corrections are compared or averaged, it is important that the Zernike coefficients have been calculated for the correct size, position, orientation, and shape of the pupil. We present the first complete theory to transform Zernike coefficients analytically with regard to concentric scaling, translation of pupil center, and rotation. The transformations are described both for circular and elliptical pupils. The algorithm has been implemented in MATLAB, for which the code is given in an appendix.

  • 163.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Unwrapping Hartmann-Shack images from highly aberrated eyes using an iterative B-spline based extrapolation method2004Ingår i: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 81, nr 5, s. 383-388Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose. When the wavefront aberrations of the eye are measured with a Hartmann-Shack (HS) sensor, the resulting spot pattern must be unwrapped, that is, for each lenslet the corresponding spot must be identified. This puts a limitation on the measurable amount of aberrations. To extend the range of an HS sensor, a powerful unwrapping algorithm has been developed. Methods. The unwrapping algorithm starts by connecting the central HS spots to the central lenslets. It then fits a B-spline function through a least squares estimate to the deviations of the central HS spots. This function is then extrapolated to find the expected locations of HS spots for the unconnected lenslets. The extrapolation is performed gradually in an iterative manner; the closest unconnected lenslets are extrapolated and connected, and then the B-spline function is least squares fitted to all connected HS spots and extrapolated again. Results. Wavefront aberrations from eyes with high aberrations can be successfully unwrapped with the developed algorithm. The dynamic range of a typical HS sensor increases 3.5 to 13 times compared with a simple unwrapping algorithm. Conclusions. The implemented algorithm is an efficient unwrapping tool and allows the use of lenslets with a low numerical aperture and thus gives a relatively higher accuracy of measurements of the ocular aberrations.

  • 164.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Unsbo, Peter
    KTH, Tidigare Institutioner, Fysik. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Gustafsson, J
    Measuring peripheral wavefront aberrations in subjects with large central visual field loss2004Ingår i: OPHTHALMIC TECHNOLOGIES XIV / [ed] Manns, F; Soderberg, PG; Ho, A, BELLINGHAM: SPIE-INT SOC OPTICAL ENGINEERING , 2004, Vol. 5314, s. 209-219Konferensbidrag (Refereegranskat)
    Abstract [en]

    In a previous study we have shown that correction of peripheral refractive errors can improve the remaining vision in the preferred retinal location (PRL) of subjects with large central visual field loss (CFL). Measuring peripheral refractive errors with traditional methods is often difficult due to the low visual acuity and large aberrations. Therefore a Hartmann-Shack (HS) sensor has been designed to measure peripheral wavefront aberrations in CFL subjects. Method: The HS sensor incorporates an eyetracker and analyzing software designed to handle large wavefront aberrations. To ensure that the measurement axis is aligned with the subject's PRL, a special fixation target has been developed. It consists of concentric rings surrounding the aperture of the HS together with a central fixation mark along the measurement axis. Results: Some initial measurements on subjects with CFL have been performed successfully. As a first step in improving the peripheral optics of the eye, the wavefront data have been used to calculate the subject's optimal eccentric refraction. Conclusion: Measuring the wavefront aberrations is a fast and easy way to assess the details of the optics in subjects with CFL. The wavefront data can then be used to better understand the problems of eccentric correction.

  • 165.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Gustafsson, Jörgen
    Lund University, Certec, Rehabilitation Engineering Research, Department of Design Sciences, Lund.
    Off-axis wave front measurements for optical correction in eccentric viewing2005Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 10, nr 3, s. 034002-1-034002-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a previous study we have shown that correction of peripheral refractive errors can improve the remaining vision of subjects with large central visual field loss. Measuring peripheral refractive errors with traditional methods is often difficult due to low visual acuity and large aberrations. Therefore a Hartmann-Shack sensor has been designed to measure peripheral wave front aberrations in subjects using eccentric viewing. The sensor incorporates an eye tracker and analyzing software designed to handle large wave front aberrations and elliptic pupils. To ensure that the measurement axis is aligned with the direction of the subject's preferred retinal location, a special fixation target has been developed. It consists of concentric rings surrounding the aperture of the sensor together with a central fixation mark along the measurement axis. Some initial measurements on subjects using eccentric viewing have been performed successfully. As a first step in improving the peripheral optics of the eye, the wave front has been used to calculate the eccentric refraction. This refraction has been compared to the refraction found with the Power-Refractor instrument. Measuring the off-axis wave front is a fast way to assess the optical errors in the subject's eccentric viewing angle and to better understand the problems of eccentric correction.

  • 166.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Venkataraman, Abinaya Priya
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Lewis, Peter R.
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Spatiotemporal contrast sensitivity in the 10 degrees visual field2016Ingår i: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 57, nr 12Artikel i tidskrift (Refereegranskat)
  • 167.
    Lundström, Ulf
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Phase-Contrast X-Ray Carbon Dioxide Angiography2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Faskontrastavbildning med röntgenstrålning är en relativt ny teknik som gör det möjligt att avbilda mindre detaljer än vanlig absorptionsbaserad röntgen, med lägre stråldos. Där normalt dämpningen av strålningen registreras, används istället det fasskift som strålningen får då den går genom ett objekt. Detta fasskift kan få röntgenstrålarna att ändra riktning, vilket kan mätas på olika sätt. Propagationsbaserad faskontrast, som har använts mest i denna avhandling, detekterar avvikelserna i fasen med hjälp av en röntgenkamera med hög upplösning en bit bakom objektet. Denna avhandling beskriver hur faskontrast kan användas för att avbilda inre strukturer i små djur som möss och råttor. En teknik för avbildning av mycket små blodkärl har utvecklats och analyserats. Genom att injicera en gas, såsom koldioxid, in i kärlsystemet har blodkärl ner till 8 µm i diameter visualiserats. Detta är betydligt mindre än de 50 µm-kärl som kan avbildas med jodbaserade kontrastmedel vid stråldoser som går att använda på levande försöksdjur. En nyligen uppfunnen typ av röntgenkälla, som skjuter elektroner på en stråle av flytande metall, har använts och utvecklats för avbildningen i denna avhandling. Dessa metallstrålekällor ger mycket röntgenstrålning för den lilla källpunkt de har, något som varit avgörande för kvaliteten på faskontrastbilderna i denna avhandling.

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    Lundström thesis
  • 168.
    Lundström, Ulf
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Larsson, Daniel H.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Burvall, Anna
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Scott, L.
    Westermark, U. K.
    Wilhelm, M.
    Henriksson, M. Arsenian
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    X-ray phase-contrast CO2 angiography for sub-10 mu m vessel imaging2012Ingår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 57, nr 22, s. 7431-7441Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    X-ray in-line phase contrast has recently been combined with CO2 angiography for high-resolution small-animal vascular imaging at low radiation dose. In this paper we further investigate the potential and limitations of this method and demonstrate observation of vessels down to 8 mu m in diameter, considerably smaller than the 60 mu m previously reported. Our in-line phase-contrast imaging system is based on a liquid-metal-jet-anode x-ray source and utilizes free-space propagation to convert phase shifts, caused by refractive index variations, into intensity differences. Enhanced refractive index variations are obtained through injection of CO2 gas into the vascular system to replace the blood. We show rat-kidney images with blood vessels down to 27 mu m in diameter and mouse-ear images with vessels down to 8 mu m. The minimum size of observable blood vessels is found to be limited by the penetration of gas into the vascular system and the signal-to-noise ratio, i.e. the allowed dose. The diameters of vessels being gas-filled depend on the gas pressure and follow a simple model based on surface tension. A theoretical signal-to-noise comparison shows that this method requires 1000 times less radiation dose than conventional iodine-based absorption contrast for observing sub-50 mu m vessels.

  • 169.
    Lundström, Ulf
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Larsson, Daniel H.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Burvall, Anna
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Takman, Per A. C.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Scott, L.
    Brismar, H.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    X-ray phase contrast for CO2 microangiography2012Ingår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 57, nr 9, s. 2603-2617Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate a laboratory method for imaging small blood vessels using x-ray propagation-based phase-contrast imaging and carbon dioxide (CO2) gas as a contrast agent. The limited radiation dose in combination with CO2 being clinically acceptable makes the method promising for small-diameter vascular visualization. We investigate the possibilities and limitations of the method for small-animal angiography and compare it with conventional absorption-based x-ray angiography. Photon noise in absorption-contrast imaging prevents visualization of blood vessels narrower than 50 mu m at the highest radiation doses compatible with living animals, whereas our simulations and experiments indicate the possibility of visualizing 20 mu m vessels at radiation doses as low as 100 mGy. Experimental computed tomography of excised rat kidney shows blood vessels of diameters down to 60 mu m with improved image quality compared to absorption-based methods. With our present prototype x-ray source, the acquisition time for a tomographic dataset is approximately 1 h, which is long compared to the 1-20 min common for absorption-contrast micro-CT systems. Further development of the liquid-metal-jet microfocus x-ray sources used here and high-resolution x-ray detectors shows promise to reduce exposure times and make this high-resolution method practical for imaging of living animals.

  • 170.
    Lundström, Ulf
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Larsson, Daniel H.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Takman, Per
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Scott, L.
    Burvall, Anna
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    X-ray phase contrast angiography using CO 2 as contrast agent2012Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2012, Vol. 8313, s. 83135J-Konferensbidrag (Refereegranskat)
    Abstract [en]

    We investigate the possibility of using x-ray in-line phase-contrast imaging with gaseous carbon dioxide as contrast agent to visualize small blood vessels. These are difficult to image at reasonable radiation doses using the absorption of conventional iodinated contrast agents. In-line phase contrast is a method for retrieving information on the electron density of the sample as well as the absorption, by moving the detector away from the sample to let phase variations in the transmitted x-rays develop into intensity variations at the detector. Blood vessels are normally difficult to observe in phase contrast even with iodinated contrast agents as the density difference compared to most tissues is small. Carbon dioxide is a clinically accepted x-ray contrast agent. The gas is injected into the blood stream of patients to temporarily displace the blood in a region and thereby reduce the x-ray absorption in the blood vessels. This gives a large density difference which is ideal for phase-contrast imaging. We demonstrate the possibilities of the method by imaging the arterial system of a rat kidney injected with carbon dioxide. Vessels down to 23 ÎŒm in diameter are shown. The method shows potential for live small-animal imaging.

  • 171.
    Lundström, Ulf
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Larsson, Daniel H.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Westermark, U. K.
    Burvall, Anna
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Small-Animal microangiography using phase-contrast X-ray imaging and gas as contrast agent2014Ingår i: Medical Imaging 2014: Physics of Medical Imaging, SPIE - International Society for Optical Engineering, 2014, s. 90331L-Konferensbidrag (Refereegranskat)
    Abstract [en]

    We use propagation-based phase-contrast X-ray imaging with gas as contrast agent To visualize The microvasculature in small animals like mice and rats. The radiation dose required for absorption X-ray imaging is proportional To The minus fourth power of The structure size To be detected. This makes small vessels impossible To image at reasonable radiation doses using The absorption of conventional iodinated contrast agents. Propagation-based phase contrast gives enhanced contrast for high spatial frequencies by moving The detector away from The sample To let phase variations in The Transmitted X-rays develop into intensity variations at The detector. Blood vessels are normally difficult To observe in phase contrast even with iodinated contrast agents as The density difference between blood and most Tissues is relatively small. By injecting gas into The blood stream This density difference can be greatly enhanced giving strong phase contrast. One possible gas To use is carbon dioxide, which is a clinically accepted X-ray contrast agent. The gas is injected into The blood stream of patients To Temporarily displace The blood in a region and Thereby reduce The X-ray absorption in The blood vessels. We have shown That This method can be used To image blood vessels down To 8 μm in diameter in mouse ears. The low dose requirements of This method indicate a potential for live small-Animal imaging and longitudinal studies of angiogenesis.

  • 172.
    Lundström, Ulf
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Westermark, Ulrica K.
    Larsson, Daniel H.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Burvall, Anna
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Arsenian Henriksson, Marie
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    X-ray phase contrast with injected gas for tumor microangiography2014Ingår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 59, nr 11, s. 2801-2811Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We show that the microvasculature of mouse tumors can be visualized using propagation-based phase-contrast x-ray imaging with gas as the contrast agent. The large density difference over the gas-tissue interface provides high contrast, allowing the imaging of small-diameter blood vessels with relatively short exposure times and low dose using a compact liquid-metal-jet x-ray source. The method investigated is applied to tumors (E1A/Ras-transformed mouse embryonic fibroblasts) grown in mouse ears, demonstrating sub-15-mu m-diameter imaging of their blood vessels. The exposure time for a 2D projection image is a few seconds and a full tomographic 3D map takes some minutes. The method relies on the strength of the vasculature to withstand the gas pressure. Given that tumor vessels are known to be more fragile than normal vessels, we investigate the tolerance of the vasculature of 12 tumors to gas injection and find that a majority withstand 200 mbar pressures, enough to fill 12-mu m-diameter vessels with gas. A comparison of the elasticity of tumorous and non-tumorous vessels supports the assumption of tumor vessels being more fragile. Finally, we conclude that the method has the potential to be extended to the imaging of 15 mu m vessels in thick tissue, including mouse imaging, making it of interest for, e.g., angiogenesis research.

  • 173.
    Makita, M.
    et al.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Vartiainen, I.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Mohacsi, I.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland.;LOrme Merisiers, Synchrotron SOLEIL, F-91190 Saint Aubin, France..
    Caleman, C.
    Deutsch Elektronen Synchrotron DESY, CFEL, D-22667 Hamburg, Germany.;Uppsala Univ, Dept Phys & Astron, SE-751 Uppsala, Sweden..
    Diaz, A.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Jönsson, Henrik Olof
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik. Department of Physics and Astronomy, Uppsala University, SE-751 24, Uppsala, Sweden.
    Juranic, P.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Medvedev, N.
    Czech Acad Sci, Inst Phys, Prague 18221 8, Czech Republic.;Czech Acad Sci, Inst Plasma Phys, Prague 18200 8, Czech Republic..
    Meents, A.
    Deutsch Elektronen Synchrotron DESY, CFEL, D-22667 Hamburg, Germany..
    Mozzanica, A.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Opara, N. L.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland.;Univ Basel, C CINA Biozentrum, CH-4058 Basel, Switzerland..
    Padeste, C.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Panneels, V.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Saxena, V.
    Deutsch Elektronen Synchrotron DESY, CFEL, D-22667 Hamburg, Germany.;Bhat, Inst Plasma Res, Gandhinagar 382428, India..
    Sikorski, M.
    SLAC Natl Accelerator Lab, Linac Coherent Light Source, Menlo Pk, CA 94025 USA..
    Song, S.
    Vera, L.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Willmott, P. R.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Beaud, P.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Milne, C. J.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Ziaja-Motyka, B.
    Deutsch Elektronen Synchrotron DESY, CFEL, D-22667 Hamburg, Germany.;Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    David, C.
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Femtosecond phase-transition in hard x-ray excited bismuth2019Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikel-id 602Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The evolution of bismuth crystal structure upon excitation of its A(1g) phonon has been intensely studied with short pulse optical lasers. Here we present the first-time observation of a hard x-ray induced ultrafast phase transition in a bismuth single crystal at high intensities (similar to 10(14) W/cm(2)). The lattice evolution was followed using a recently demonstrated x-ray single-shot probing setup. The time evolution of the (111) Bragg peak intensity showed strong dependence on the excitation fluence. After exposure to a sufficiently intense x-ray pulse, the peak intensity dropped to zero within 300 fs, i.e. faster than one oscillation period of the A(1g) mode at room temperature. Our analysis indicates a nonthermal origin of a lattice disordering process, and excludes interpretations based on electron-ion equilibration process, or on thermodynamic heating process leading to plasma formation.

  • 174.
    Malek Khachatourian, Adrine
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM. Iran University of Science and Technology, Iran .
    Golestani-Fard, Farhad
    Sarpoolaky, Hossein
    Vogt, Carmen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Microwave assisted synthesis of monodispersed Y2O3 and Y2O3:Eu3+ particles2015Ingår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 41, nr 2, s. 2006-2014Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Monodisperse spherical Y2O3 and Y2O3:Eu3+ nanocrystalline particles with particle size between 100 nm and 350 nm were successfully prepared by microwave assisted urea precipitation method followed by a thermochemical treatment. Fast microwave heating, controlled decomposition of urea and burst nucleation of metal ions in aqueous solution led to the formation of non-aggregated spherical particles with narrow size dispersion. The particle size and size dispersion was controlled by adjusting the urea/metal ions ratio, the metal ions concentration, the reaction time and the temperature. X-ray diffraction (XRD) analysis indicated that the as prepared particles have Y(OH)CO3 composition, which converted to highly crystalline cubic Y2O3 after calcination at temperatures above 600 degrees C. The calcined Y2O3 particles preserved the spherical morphology of the as prepared particles and exhibited polycrystalline structure. The size of the crystallites increased from similar to 8 nm to similar to 37 nm with the increase of the calcination temperature from 500 degrees C to 900 degrees C. In order to transform these nanostructures to luminescent composition, Eu3+ doping has been performed. Y2O3:Eu3+ particles inherited the morphology and polycrystalline structure of the host Y2O3 particles. Photoluminescence (PL) analysis of Y2O3:Eu3+ particles showed a strong red emission peak at 613 nm corresponding to D-5(0)-F-7(2) forced electric dipole transition of Eu3+ ions under UV excitation. All these critical characteristics, and being heavy-metal free, make these particles useful for bioimaging, and display devices.

  • 175. Malmqvist, S.
    et al.
    Liljeborg, Anders V. G.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Qadri, T.
    Johannsen, G.
    Johannsen, A.
    Using 445 nm and 970 nm lasers on dental implants-an in vitro study on change in temperature and surface alterations2019Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, nr 23, artikel-id 3934Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study was to evaluate the safety of using a 445 nm laser on dental implants by comparing it with a laser with 970 nm wavelength. Two models, a pig mandible and glass ionomer cement, were used to evaluate the temperature increase in dental implants during laser irradiation with both wavelengths. Temperature was measured every second at four different places on the dental implants. Different power settings, effects of water cooling, distance of the laser fibre to the dental implant and continuous comparison to a pulsed laser beam were tested. Surface alterations on titanium discs after laser irradiation for 4 min at 2.0 W, were analysed in a scanning electron microscope (SEM). The maximum temperature and time to reach each of the thresholds were comparable between the 445 nm and 970 nm lasers. Neither the 445 nm nor the 970 nm wavelength showed any signs of surface alterations on the titanium discs. Using a 445 nm laser on dental implants is as safe as using a 970 nm laser, in terms of temperature increase and surface alterations. Applying a generous amount of cooling water and irradiating in short intervals is important when using lasers on dental implants.

  • 176.
    Malmqvist, Sebastian
    et al.
    Karolinska Inst, Div Oral Dis, Dept Dent Med, S-14152 Huddinge, Sweden..
    Liljeborg, Anders V. G.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Qadri, Talat
    Karolinska Inst, Div Oral Dis, Dept Dent Med, S-14152 Huddinge, Sweden..
    Johannsen, Gunnar
    Karolinska Inst, Div Oral Dis, Dept Dent Med, S-14152 Huddinge, Sweden.;Praktikertjanst AB, Danakliniken Specialisttandvard, S-18231 Danderyd, Sweden..
    Johannsen, Annsofi
    Karolinska Inst, Div Oral Dis, Dept Dent Med, S-14152 Huddinge, Sweden..
    Using 445 nm and 970 nm Lasers on Dental Implants-An In Vitro Study on Change in Temperature and Surface Alterations2019Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, nr 23, artikel-id 3934Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study was to evaluate the safety of using a 445 nm laser on dental implants by comparing it with a laser with 970 nm wavelength. Two models, a pig mandible and glass ionomer cement, were used to evaluate the temperature increase in dental implants during laser irradiation with both wavelengths. Temperature was measured every second at four different places on the dental implants. Different power settings, effects of water cooling, distance of the laser fibre to the dental implant and continuous comparison to a pulsed laser beam were tested. Surface alterations on titanium discs after laser irradiation for 4 min at 2.0 W, were analysed in a scanning electron microscope (SEM). The maximum temperature and time to reach each of the thresholds were comparable between the 445 nm and 970 nm lasers. Neither the 445 nm nor the 970 nm wavelength showed any signs of surface alterations on the titanium discs. Using a 445 nm laser on dental implants is as safe as using a 970 nm laser, in terms of temperature increase and surface alterations. Applying a generous amount of cooling water and irradiating in short intervals is important when using lasers on dental implants.

  • 177.
    Manneberg, Otto
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Multidimensional Ultrasonic Standing Wave Manipulation in Microfluidic Chips2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The use of ultrasonic standing waves for contactless manipulation of microparticles in microfluidic systems is a field with potential to become a new standard tool in lab-on-chip systems. Compared to other contactless manipulation methods ultrasonic standing wave manipulation shows promises of gentle cell handling, low cost, and precise temperature control. The technology can be used both for batch handling, such as sorting and aggregation, and handling of single particles.

    This doctoral Thesis presents multi-dimensional ultrasonic manipulation, i.e., manipulation in both two and three spatial dimensions as well as time-dependent manipulation of living cells and microbeads in microfluidic systems. The lab-on-chip structures used allow for high-quality optical microscopy, which is central to many bio-applications. It is demonstrated how the ultrasonic force fields can be spatially confined to predefined regions in the system, enabling sequential manipulation functions. Furthermore, it is shown how frequency-modulated signals can be used both for spatial stabilization of the force fields as well as for flow-free transport of particles in a microchannel. Design parameters of the chip-transducer systems employed are investigated experimentally as well as by numerical simulations. It is shown that three-dimensional resonances in the solid structure of the chip strongly influences the resonance shaping in the channel.

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    FULLTEXT02
  • 178.
    Manneberg, Otto
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hultström, Jessica
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Dynamics of ultrasonic standing wave nodal patterns in a microfluidic chip by acoustic streaming and coupling effects2007Ingår i: Proc. 1st International Congress on Ultrasonics, 2007Konferensbidrag (Refereegranskat)
  • 179.
    Manneberg, Otto
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hultström, Jessica
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Elementary manipulation functions for gentle and long-term handling of cells in micro-channels by ultrasonic standing waves2006Ingår i: Proc. 10th Annual European Conference on Micro & Nanoscale Technologies for the Biosciences, 2006Konferensbidrag (Refereegranskat)
  • 180.
    Manneberg, Otto
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hultström, Jessica
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Proliferation of adherent cells manipulated by standing wave ultrasound in a microfluidic chip2006Konferensbidrag (Övrigt vetenskapligt)
  • 181.
    Manneberg, Otto
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Rosén, Robert
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Högfeldt, Anna-Karin
    KTH, Skolan för teknikvetenskaplig kommunikation och lärande (ECE), Lärande.
    Manneberg, Göran
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Edström, Kristina
    KTH, Skolan för teknikvetenskaplig kommunikation och lärande (ECE), Lärande. KTH, Skolan för industriell teknik och management (ITM), Lärande.
    En struktur för ökad funktionell kunskap hos studenten från räkneövningar2008Konferensbidrag (Refereegranskat)
    Abstract [sv]

    En struktur för räkneövningar med syftet att ge studenten ökade funktionella kunskaper och färdigheter i ämnet presenteras. Strukturen är avsedd att aktivera studenten både innan och under en räkneövning. Genom kamraträttning av frivilliga hemuppgifter frikopplade från bonussystem, student-student-diskussioner samt diskussion i helklass antas studenten uppmuntras till djupare lärstrategier och nå en högre taxonominivå inom ämnet.Strukturen utprovas på två studentgrupper; andraårsstudenter på ett civilingenjörsprogram på KTH, samt förstårsstudenter på optikerutbildningen på Karolinska Institutet som läser optikkurser vid KTH. Utvärdering sker under pågående kurs genom enkäter till alla studenterna samt intervjuer av optikerstudenter, samt efter fullgången kurs genom intervjuer av assistenter och ingenjörsstudenter. Resultaten visar att studenterna ställer sig positiva till det nya systemet och anser att det ger dem en djupare nivå av förståelse, att det skapar en mer transparent bild av rättningsprocessen, samt att det ökar interaktionen mellan studenter och skapar en bättre klassrumsmiljö. Deltagandet är stort bland optikerstudenterna, medan ingenjörsstudenterna anser att de har betydligt svårare att hitta tid till hemuppgifterna.

  • 182.
    Manneberg, Otto
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Strååt, Johan
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Multidimensional ultrasonic manipulation stabilized by frequency modulation2008Konferensbidrag (Övrigt vetenskapligt)
  • 183.
    Manneberg, Otto
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Svennebring, Jessica
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Towards spatially confined ultrasonic standing wave fields in a microfluidic chip by microchannel design2007Konferensbidrag (Refereegranskat)
  • 184.
    Manneberg, Otto
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Svennebring, Jessica
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Ultrasonic micro-cages: A new approach for manipulation and monitoring of individual cells and for fluid mixing2008Ingår i: 12th International Conference on Miniaturized Systems for Chemistry and Life Sciences - The Proceedings of MicroTAS 2008 Conference, Chemical and Biological Microsystems Society , 2008, s. 1495-1497Konferensbidrag (Refereegranskat)
    Abstract [en]

    Four designs of ultrasonic microcages are presented together with force field simulations and experimental verification. The microcages enable three-dimensional ultrasonic manipulation of individual microparticles combined with on-line monitoring using high-resolution optical microscopy. The microcages can also be employed as acoustic-streaming-based micromixers. We investigate and compare the force field distributions and streaming patterns in the cages, and we demonstrate concentration, aggregation and positioning of individual particles. The cages can be used for, e.g., studies of interactions between single cells and functionalized particles or pairs of cells in contact only with each other.

  • 185.
    Manneberg, Otto
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Svennebring, Jessica
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Wedge transducer design for two-dimensional ultrasonic manipulation in a microfluidic chip2008Ingår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 18, s. 095025-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We analyze and optimize the design of wedge transducers used for the excitation of resonances in the channel of a microfluidic chip in order to efficiently manipulate particles or cells in more than one dimension. The design procedure is based on (1) theoretical modeling of acoustic resonances in the transducer-chip system and calculation of the force fields in the fluid channel, (2) full-system resonance characterization by impedance spectroscopy and (3) image analysis of the particle distribution after ultrasonic manipulation. We optimize the transducer design in terms of actuation frequency, wedge angle and placement on top of the chip, and we characterize and compare the coupling effects in orthogonal directions between single- and dual-frequency ultrasonic actuation. The design results are verified by demonstrating arraying and alignment of particles in two dimensions. Since the device is compatible with high-resolution optical microscopy, the target application is dynamic cell characterization combined with improved microfluidic sample transport.

  • 186.
    Manneberg, Otto
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vanherberghen, Bruno
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik.
    Svennebring, Jessica
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Önfelt, Björn
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    A three-dimensional ultrasonic cage for characterization of individual cells2008Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 93, s. 063901-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate enrichment, controlled aggregation, and manipulation of microparticles and cells by an ultrasonic cage integrated in a microfluidic chip compatible with high-resolution optical microscopy. The cage is designed as a dual-frequency resonant filleted square box integrated in the fluid channel. Individual particles may be trapped three dimensionally, and the dimensionality of one-dimensional to three-dimensional aggregates can be controlled. We investigate the dependence of the shape and position of a microparticle aggregate on the actuation voltages and aggregate size, and demonstrate optical monitoring of individually trapped live cells with submicrometer resolution.

  • 187.
    Manneberg, Otto
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vanherberghen, Bruno
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik.
    Svennebring, Jessica
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Önfelt, Björn
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Ultrasonic microcages for high-resolution characterization of individual cells2008Konferensbidrag (Refereegranskat)
  • 188. Marcos, S.
    et al.
    Werner, J. S.
    Burns, S. A.
    Merigan, W. H.
    Artal, P.
    Atchison, D. A.
    Hampson, K. M.
    Legras, R.
    Lundström, Linda
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Yoon, G.
    Carroll, J.
    Choi, S. S.
    Doble, N.
    Dubis, A. M.
    Dubra, A.
    Elsner, A.
    Jonnal, R.
    Miller, D. T.
    Paques, M.
    Smithson, H. E.
    Young, L. K.
    Zhang, Y.
    Campbell, M.
    Hunter, J.
    Metha, A.
    Palczewska, G.
    Schallek, J.
    Sincich, L. C.
    Vision science and adaptive optics, the state of the field2017Ingår i: Vision Research, ISSN 0042-6989, E-ISSN 1878-5646, Vol. 132, s. 3-33Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Adaptive optics is a relatively new field, yet it is spreading rapidly and allows new questions to be asked about how the visual system is organized. The editors of this feature issue have posed a series of question to scientists involved in using adaptive optics in vision science. The questions are focused on three main areas. In the first we investigate the use of adaptive optics for psychophysical measurements of visual system function and for improving the optics of the eye. In the second, we look at the applications and impact of adaptive optics on retinal imaging and its promise for basic and applied research. In the third, we explore how adaptive optics is being used to improve our understanding of the neurophysiology of the visual system.

  • 189.
    Martz, Dale H.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Selin, Mårten
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    von Hofsten, Olov
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Fogelqvist, Emelie
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Holmberg, Anders
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Ulrich
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Legall, H.
    Blobel, G.
    Seim, C.
    Stiel, H.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    High average brightness water window source for short-exposure cryomicroscopy2012Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, nr 21, s. 4425-4427Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laboratory water window cryomicroscopy has recently demonstrated similar image quality as synchrotron-based microscopy but still with much longer exposure times, prohibiting the spread to a wider scientific community. Here we demonstrate high-resolution laboratory water window imaging of cryofrozen cells with 10 s range exposure times. The major improvement is the operation of a lambda = 2.48 nm, 2 kHz liquid nitrogen jet laser plasma source with high spatial and temporal stability at high average brightness >1.5 x 10(12) ph/(s x sr x mu m(2) x line), i.e., close to that of early synchrotrons. Thus, this source enables not only biological x-ray microscopy in the home laboratory but potentially other applications previously only accessible at synchrotron facilities.

  • 190.
    Meszaros, Johan
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Large area zone plate exposure by fixed beam moving stage lithography2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this diploma project the so-called fixed beam moving stage (FBMS) module in the Raith 150 electron beam lithography system has been evaluated for making large area zone plate exposures. The project goal, besides the evaluation of the module, has been to find an exposure recipe for exposing zone plates with diameter up to 500 μm. The zone plates fabricated with this method will be used for synchrotron and x-ray free electron laser applications.

    The thesis starts with a short introduction to zone plate properties and fabrication procedures. Then the work where FBMS exposed zone plates are compared with normal write field exposures of 75 μm diameter zone plates is described. The conclusion is that for these small diameters, major problems with wobbly zones occur for the FBMS patterns. However, for larger diameters the pattern typically looks better. The final result with large area exposures are excellent zone plate patterns with 500 μm diameter and 100 nm outermost zone width. The total exposure time was 2 h 15 min. This relatively short time indicate that it will be practically possible to use the Raith system for these large area exposures.

    Ladda ner fulltext (pdf)
    fulltext
  • 191.
    Mi, Wujun
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Karlsson, Staffan
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Holmberg, Anders
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Danielsson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Nillius, Peter
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik.
    Fabrication of circular sawtooth gratings using focused UV lithography2016Ingår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 26, nr 3, artikel-id 035001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    AbstractThis paper presents a novel micro-fabrication method using focused ultraviolet (UV) light to manufacture three-dimensional sawtooth structures in ultra-thick negative photoresist to fabricate a novel multi-prism x-ray lens. The method uses a lens to shape the UV beam instead of the photomask conventionally used in UV lithography. Benefits of this method include the ability to manufacture sawtooth structures in free form, for example in circular shapes as well as arrays of these shapes, and in resist that is up to 76 μm thick.To verify the method, initially a simple simulation based on Fourier optics was done to predict the exposure energy distribution in the photoresist. Furthermore, circular sawtooth gratings were manufactured in a 76 μm SU-8 resist. The UV lens was fabricated using electron beam lithography and then used to expose the SU-8 with UV light. This paper details the complete developed process, including pre-exposure with an e-beam and cold development, which creates stable sawtooth structures. The measured profile was compared to the ideal sawtooth and the simulation. The main discrepancy was in the smallest feature size, the sawtooth tips, which were wider than the desired structures, as would be expected by simulation.

  • 192.
    Mohamed, Alaa
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Cairo University, Egypt.
    Nasser, W. S.
    Osman, T. A.
    Toprak, Muhammet
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Muhammed, Mamoun
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Alexandria University, Egypt.
    Uheida, Abdusalam
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Removal of chromium (VI) from aqueous solutions using surface modified composite nanofibers2017Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 505, s. 682-691Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel material composite nanofibers (PAN-CNT/TiO2-NH2) based on adsorption of Cr(VI) ions, was applied. Polyacrylonitrile (PAN) and carbon nanotube (CNTs)/titanium dioxide nanoparticles (TiO2) functionalized with amine groups (TiO2-NH2) composite nanofibers have been fabricated by electrospinning. The nanostructures and the formation process mechanism of the obtained PAN-CNT/TiO2-NH2 composite nanofibers are investigated using FTIR, XRD, XPS, SEM, and TEM. The composite nanofibers were used as a novel adsorbent for removing toxic chromium Cr(VI) in aqueous solution. The kinetic study, adsorption isotherm, pH effect, initial concentration, and thermodynamic study were investigated in batch experiments. The composite nanofibers had a positive effect on the absorption of Cr(VI) ions under neutral and acidic conditions, and the saturated adsorption reached the highest when pH was 2. The adsorption equilibrium reached within 30 and 180 min with an initial solution concentration increasing from 10 to 300 mg/L, and the process can be better described using nonlinear pseudo first than nonlinear pseudo second order model and Intra-particle diffusion. Isotherm data fitted well using linear and nonlinear Langmuir, Freundlich, Redlich-Peterson, and Temkin isotherm adsorption model. Thermodynamic study showed that the adsorption process is exothermic. The adsorption capacity can remain up to 80% after 5 times usage, which show good durability performance. The adsorption mechanism was also studied by UV-vis and XPS.

  • 193. Mukherjee, S. P.
    et al.
    Gliga, A. R.
    Lazzaretto, B.
    Brandner, B.
    Fielden, Matthew
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Vogt, Carmen
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Newman, L.
    Rodrigues, A. F.
    Shao, W.
    Fournier, P. M.
    Toprak, Muhammet Sadaka
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Star, A.
    Kostarelos, K.
    Bhattacharya, K.
    Fadeel, B.
    Graphene oxide is degraded by neutrophils and the degradation products are non-genotoxic2018Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, nr 3, s. 1180-1188Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Neutrophils were previously shown to digest oxidized carbon nanotubes through a myeloperoxidase (MPO)-dependent mechanism, and graphene oxide (GO) was found to undergo degradation when incubated with purified MPO, but there are no studies to date showing degradation of GO by neutrophils. Here we produced endotoxin-free GO by a modified Hummers' method and asked whether primary human neutrophils stimulated to produce neutrophil extracellular traps or activated to undergo degranulation are capable of digesting GO. Biodegradation was assessed using a range of techniques including Raman spectroscopy, transmission electron microscopy, atomic force microscopy, and mass spectrometry. GO sheets of differing lateral dimensions were effectively degraded by neutrophils. As the degradation products could have toxicological implications, we also evaluated the impact of degraded GO on the bronchial epithelial cell line BEAS-2B. MPO-degraded GO was found to be non-cytotoxic and did not elicit any DNA damage. Taken together, these studies have shown that neutrophils can digest GO and that the biodegraded GO is non-toxic for human lung cells.

  • 194. Munke, Anna
    et al.
    Andreasson, Jakob
    Aquila, Andrew
    Awel, Salah
    Ayyer, Kartik
    Barty, Anton
    Bean, Richard J.
    Berntsen, Peter
    Bielecki, Johan
    Boutet, Sebastien
    Bucher, Maximilian
    Chapman, Henry N.
    Daurer, Benedikt J.
    DeMirci, Hasan
    Elser, Veit
    Fromme, Petra
    Hajdu, Janos
    Hantke, Max F.
    Higashiura, Akifumi
    Hogue, Brenda G.
    Hosseinizadeh, Ahmad
    Kim, Yoonhee
    Kirian, Richard A.
    Reddy, Hemanth K. N.
    Lan, Ti-Yen
    Larsson, Daniel S. D.
    Liu, Haiguang
    Loh, N. Duane
    Maia, Filipe R. N. C.
    Mancuso, Adrian P.
    Muhlig, Kerstin
    Nakagawa, Atsushi
    Nam, Daewoong
    Nelson, Garrett
    Nettelblad, Carl
    Okamoto, Kenta
    Ourmazd, Abbas
    Rose, Max
    van der Schot, Gijs
    Schwander, Peter
    Seibert, M. Marvin
    Sellberg, Jonas A.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Sierra, Raymond G.
    Song, Changyong
    Svenda, Martin
    Timneanu, Nicusor
    Vartanyants, Ivan A.
    Westphal, Daniel
    Wiedorn, Max O.
    Williams, Garth J.
    Xavier, Paulraj Lourdu
    Yoon, Chun Hong
    Zook, James
    Data Descriptor: Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source2016Ingår i: Scientific Data, E-ISSN 2052-4463, Vol. 3, artikel-id UNSP 160064Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a wellcharacterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 mu m diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 angstrom ngstrom were recorded. The diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here.

  • 195.
    Mühlig, Kerstin
    et al.
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden. .
    Gañán-Calvo, Alfonso M.
    Andreasson, Jakob
    Larsson, Daniel S. D.
    Hajdu, Janos
    Svenda, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik. Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, Husargatan 3,Box 596, SE-75124 Uppsala, Sweden.
    Nanometre-sized droplets from a gas dynamic virtual nozzle2019Ingår i: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 52, s. 800-808Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports on improved techniques to create and characterize nometre-sized droplets from dilute aqueous solutions by using a gas namic virtual nozzle (GDVN). It describes a method to measure the size stribution of uncharged droplets, using an environmental scanning ectron microscope, and provides theoretical models for the droplet zes created. The results show that droplet sizes can be tuned by justing the gas and liquid flow rates in the GDVN, and at the lowest quid flow rates, the size of the water droplets peaks at about 120nm. is droplet size is similar to droplet sizes produced by electrospray nization but requires neither electrolytes nor charging of the lution. The results presented here identify a new operational regime r GDVNs and show that predictable droplet sizes, comparable to those tained by electrospray ionization, can be produced by purely chanical means in GDVNs.

  • 196. Nachtrab, F.
    et al.
    Firsching, M.
    Speier, C.
    Uhlmann, N.
    Takman, P.
    Tuohimaa, T.
    Heinzl, C.
    Kastner, J.
    Larsson, Daniel
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinsk bildteknik.
    Holmberg, Anders
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Berti, G.
    Krumm, M.
    Sauerwein, C.
    NanoXCT: Development of a laboratory nano-CT system2014Ingår i: Proceedings of SPIE - The International Society for Optical Engineering, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The NanoXCT project aims at developing a laboratory nano-CT system for non-destructive testing applications in the micro- and nano-technology sector. The system concept omits the use of X-ray optics, to be able to provide up to 1 mm FOV (at 285 nm voxel size) and down to 50 nm voxel size (at 0.175 mm FOV) while preserving the flexibility of state-of-the-art micro-CT systems. Within the project a suitable X-ray source, detector and manipulation system are being developed. To cover the demand for elemental analysis, the project will additionally include X-ray spectroscopic techniques. These will be reported elsewhere while this paper is focused on the imaging part of the project. We introduce the system concept including design goals and constraints, and the individual components. We present the current state of the prototype development including first results.

  • 197. Nachtrab, F.
    et al.
    Hofmann, T.
    Speier, C.
    Lucic, J.
    Firsching, M.
    Uhlmann, N.
    Takman, P.
    Heinzl, C.
    Holmberg, Anders
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Krumm, M.
    Sauerwein, C.
    Development of a Timepix based detector for the NanoXCT project2015Ingår i: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 10, artikel-id C11009Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The NanoXCT EU FP7 project [1] aims at developing a laboratory, i.e. bench top sized X-ray nano-CT system with a large field-of-view (FOV) for non-destructive testing needs in the micro- and nano-technology sector. The targeted voxel size is 50 nm at 0.175 mm FOV, the maximum FOV is 1 mm at 285 nm voxel size. Within the project a suitable X-ray source, detector and manipulation system have been developed. The system concept [2] omits the use of X-ray optics, to be able to provide a large FOV of up to 1 mm and to preserve the flexibility of state-of-the-art micro-CT systems. The targeted resolution will be reached via direct geometric magnification made possible by the development of a specialized high-flux nano-focus transmission X-ray tube. The end-user's demand for elemental analysis will be covered by energy-resolved measurement techniques, in particular a K-edge imaging method. Timepix [3] modules were chosen as the basis for the detector system, since a photon counting detector is advantageous for the long exposure times that come with very small focal spot sizes. Additional advantages are the small pixel size and adjustable energy threshold. To fulfill the requirements on field-of-view, a detector width > 3000 pixels was needed. The NanoXCT detector consists of four Hexa modules with 500 mu m silicon sensors supplied by X-ray Imaging Europe. An adapter board was developed to connect all four modules to one Fitpix3 readout. The final detector has an active area of 3072 x 512 pixels or approximately 17 x 3 cm(2). In this contribution we present the development of the Timepix based NanoXCT detector, it's application in the NanoXCT project for CT and material specific measurements and the current status of results.

  • 198.
    Nigicser, David
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Valerio, Turri
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Mårtensson, Jonas
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik. KTH, Skolan för industriell teknik och management (ITM), Centra, Integrated Transport Research Lab, ITRL.
    Arat, Mustafa Ali
    The Goodyear Rubber & Tire Company.
    Lima Simões da Silva, Eduardo
    DTU Space.
    Predictive Vehicle Motion Control for Post-Crash Scenarios2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an active safety system for passenger vehicles designed to mitigate secondary collisions after an initial impact. Thecontrol objective is to minimize lateral deviation from the known original path while achieving a safe heading angle after the initialcollision. A hierarchical controller architecture is proposed: the higher layer is formulated as a linear time-varying model predictivecontroller that defines the virtual control moment input; the lower layer deploys a rule-based controller that realizes the requestedmoment. The designed control system is tested and validated on a high-fidelity vehicle dynamics simulator.

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  • 199. Nikkam, N.
    et al.
    Ghanbarpour, Morteza
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Khodabandeh, Rahmatollah
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Toprak, Muhammet S.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    The effect of particle size and base liquid on thermo-physical properties of ethylene and diethylene glycol based copper micro- and nanofluids2017Ingår i: International Communications in Heat and Mass Transfer, ISSN 0735-1933, E-ISSN 1879-0178, Vol. 86, s. 143-149Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanofluid (NF) is a fluid containing nanometer-sized particles. The present work investigates, experimentally and theoretically, on fabrication and thermo-physical properties evaluation of ethylene glycol and diethylene glycol (EG/DEG) based nanofluids/microfluids (NFs/MFs) containing copper nanoparticles/microparticles (NPs/MPs) with focus on the effect of the particle size and the base liquid. A series of stable Cu NFs and MFs with various NP/MP concentration (1, 2 and 3 wt%) were fabricated by dispersing Cu NPs and Cu MPs in EG and DEG as the base liquids. The physicochemical properties of Cu NFs and MFs were analyzed by various techniques including X-Ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Dynamic Light Scattering (DLS). The thermo-physical properties including thermal conductivity (TC) and viscosity of EG/DEG based Cu NFs/MFs were measured at 20 to 40 °C. The results for TC and viscosity of EG based Cu NF/MFs were compared to the same NFs/MFs with DEG base liquid with focus on the impact of the particle size as well as the base liquid. The experiments showed that EG based NFs/MFs exhibit more favorable characteristics than that of DEG based ones. Moreover, NFs with Cu NPs revealed higher TC than those MFs containing Cu MPs at the same particle concentration and temperature (effect of NP size). As the best result, a TC enhancement of ~ 4.7% was achieved for EG based NF with 3 wt% Cu NP while maximum increase in viscosity of ~ 1.8% was observed for the same NF at 20 °C. To compare the experimental results with the estimated values, Maxwell predictive correlation and Corcione model were employed while Einstein equations as well as Kriger-Dougherty correlation were applied for TC and viscosity of NFs/MFs, respectively.

  • 200. Nikkam, N.
    et al.
    Toprak, Muhammet Sadaka
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Fabrication and thermo-physical characterization of silver nanofluids: An experimental investigation on the effect of base liquid2018Ingår i: International Communications in Heat and Mass Transfer, ISSN 0735-1933, E-ISSN 1879-0178, Vol. 91, s. 196-200Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanofluids (NFs) are solid-liquid composites prepared by stabilizing nanoparticles (NPs) in a base liquid, which is selected based on the technological area of application. For heat exchange applications the base liquid can be specified as water, ethylene glycol (EG), or their mixture. NFs have exhibited some potential to replace conventional heat transfer fluids due to enhancement of their thermal characteristics. The thermo-physical properties of NFs including thermal conductivity (TC) and viscosity may be affected by several factors including the base liquid, which is not well studied in the literature. Focus of the present work is to study the impact of base liquid by comparing the TC and viscosity of a commercial silver (Ag) NFs with lab-made water, EG and water/ethylene glycol (W/EG) mixture (50:50 by wt%) at different Ag NP loadings (1, 1.5 and 2 wt%). For this purpose, commercial water based Ag suspension (containing 1 wt% Ag NP) was acquired, which is used for the preparation of Ag NFs with different base liquids and NP loadings. Finally, the thermo-physical properties of NFs including TC and viscosity were measured and analyzed at 20 °C. The results revealed that W/EG based NFs containing 2 wt% Ag NP showed best performance with the highest TC enhancement of 12.4% and only 6.1% increase in viscosity, revealing that among different base liquids, W/EG based NFs are the most beneficial for heat transfer applications.

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