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  • 101.
    Iranmanesh, Ida Sadat
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    On-chip Ultrasonic Sample Preparation2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Acoustofluidics has become a well-established technology in the lab-on-a-chip scientific community. The technology involves primarily the manipulation of fluids and/or particles in microfluidic systems. It is used today for variety of applications such as handling, sorting, washing and separation of cells or micro-particles, and for mixing and pumping of fluids. When such manipulation functions are integrated in micro-devices, the technology has been used for clinical sample preparation as well as for studying various fundamental bio-related questions.

    In this doctoral thesis, we have developed different acoustic methods and micro-devices with the aim to create a multi-functional sample preparation platform. We introduced a simple method for in-situ measurements of acoustic energy densities inside a microfluidic channel, from which acoustic pressure amplitudes can be extracted. The method has been used for determining the magnitude of acoustic radiation forces acting on suspended particles and cells inside an acoustofluidic system. For optimization of acoustophoresis (i.e. manipulation of particles into the nodes of standing waves), we have investigated different designs of ultrasonic transducers based on tunable-angle wedges and backing layers attached to glass-silicon microfluidic chips. Furthermore, we have investigated the implementation of frequency-modulated actuation methodology combined with broadbanded ultrasonic transducers, and the implementation of multiple ultrasonic manipulation functions localized to spatially separated zones in a complex microchannel network. We demonstrate two different bio-applications useful for multi-step and multi-functional sample preparation. First, we demonstrate a micro-device for size-based separation, isolation and up-concentration of cells, followed by microscopy-based dynamic monitoring of individual cell properties when introducing different reagents. This holds great promise for use in cellular and molecular diagnostics. Second, we demonstrate an acoustic method for micro-vortexing in µL-volume reaction chambers in disposable polymer chips. The method is used for fast mixing of fluids, for disaggregating and re-suspending magnetically trapped and clumped micro-beads, and for cell lysis followed by DNA extraction. Finally, we demonstrate a temperature-controlled device compatible with high-acoustic-pressure (1 MPa) ultrasonic manipulation of cells, and we demonstrate that cells can be exposed to standing-wave ultrasound at 1 MPa for one hour without compromising the cell viability.

    Ladda ner fulltext (pdf)
    Thesis
  • 102.
    Iranmanesh, Ida Sadat
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Barnkob, R.
    Bruus, H.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Tunable-angle wedge transducer for improved acoustophoretic control in a microfluidic chip2013Ingår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, nr 10, s. 105002-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a tunable-angle wedge ultrasound transducer for improved control of microparticle acoustophoresis in a microfluidic chip. The transducer is investigated by analyzing the pattern of aligned particles and induced acoustic energy density while varying the transducer geometry, transducer coupling angle, and transducer actuation method (single-frequency actuation or frequency-modulation actuation). The energy-density analysis is based on measuring the transmitted light intensity through a microfluidic channel filled with a suspension of 5 mu m diameter beads and the results with the tunable-angle transducer are compared with the results from actuation by a standard planar transducer in order to decouple the influence from change in coupling angle and change in transducer geometry. We find in this work that the transducer coupling angle is the more important parameter compared to the concomitant change in geometry and that the coupling angle may be used as an additional tuning parameter for improved acoustophoretic control with single-frequency actuation. Further, we find that frequency-modulation actuation is suitable for diminishing such tuning effects and that it is a robust method to produce uniform particle patterns with average acoustic energy densities comparable to those obtained using single-frequency actuation.

  • 103.
    Iranmanesh, Ida Sadat
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Ohlin, Mathias
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Ramachandraiah, Harisha
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Russom, Aman
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Acoustic micro-vortexing of fluids, beads and cells in disposable microfluidic chipsManuskript (preprint) (Övrigt vetenskapligt)
  • 104. Jaeken, Bart
    et al.
    Lundström, Linda
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Artal, Pablo
    Fast scanning peripheral wave-front sensor for the human eye2011Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 19, nr 8, s. 7903-7913Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We designed and built a fast scanning peripheral Hartmann-Shack (HS) wave-front sensor to measure the off-axis wave-front aberrations in the human eye. The new instrument is capable of measuring the optical quality over the central 80 degrees horizontal visual field in 1.8 seconds with an angular resolution of 1 degrees. The subject has an open field of view without any moving elements in the line-of-sight and the head is kept in place by a head-chin rest. The same efficiency, reliability and measurement quality as the current static HS sensor were found but with much higher acquisition speed and comfort for the patients. This instrument has the potential to facilitate and improve future research on the peripheral optical quality of the eye in large groups of subjects.

  • 105. Jaeken, Bart
    et al.
    Lundström, Linda
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Artal, Pablo
    Peripheral aberrations in the human eye for different wavelengths: off-axis chromatic aberration2011Ingår i: Optical Society of America. Journal A: Optics, Image Science, and Vision, ISSN 1084-7529, E-ISSN 1520-8532, Vol. 28, nr 9, s. 1871-1879Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The interest in the eye's off-axis aberrations has increased strongly. On-axis the conversion of the aberration magnitude between different wavelengths is well known. We verified if this compensation is correct also for off-axis measurements by building a wavelength tunable peripheral Hartmann-Shack sensor and measuring 11 subjects out to +/- 30 degrees in the horizontal visual field. At the fovea, an average longitudinal chromatic aberration of 1D between red (671 nm) and blue (473 nm) light was found, and it increased slightly with eccentricity (up to 1.2D). A similar trend was measured for astigmatism as a function of wavelength (increase similar to 0.15D). Computational ray tracing in model eyes showed that the origin of the small increase of chromatic aberrations with eccentricity is the change of the oblique power of the refractive surfaces in the eye. Factors related to increase of axial length and refractive index of the eye were found to have a very small influence.

  • 106.
    Jansson, Per
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Ultich
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Liquid-nitrogen-jet laser-plasma source for compact soft x-ray microscopy2005Ingår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 76, nr 4, s. 043503-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We describe a liquid-nitrogen-jet laser-plasma source with sufficient brightness, uniformity, stability, and reliability to be suitable for compact water-window soft x-ray transmission microscopy. A cooled capillary nozzle arrangement allows long-term operation and avoids previously reported jet instabilities. The source is quantitatively characterized by calibrated slit-grating spectroscopy and zone-plate imaging. The absolute photon number in the major spectral lines (lambda=2.48 nm and lambda=2.88 nm) is 1.0x10(12) photons/(pulsexsrxline). The source diameter is similar to 20 mu m (full width at half maximum) and the spatial stability is better than +/- 2 mu m. Within an area with uniformity of 20%, the average source brightness is 4x10(8) photons/(pulsexsrx mu m(2)xline), which allows operation of a compact soft x-ray transmission microscope with exposure times of a few minutes.

  • 107. Johannsen, Gunnar
    et al.
    Tellefsen, Georg
    Johannsen, Annsofi
    Liljeborg, Anders
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    The importance of measuring toothpaste abrasivity in both a quantitative and qualitative way2013Ingår i: Acta Odontologica Scandinavica, ISSN 0001-6357, E-ISSN 1502-3850, Vol. 71, nr 3-4, s. 508-517Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objective. To evaluate the relative abrasivity of different toothpastes and polishing pastes both qualitatively and quantitatively. Materials and methods. Acrylic plates were exposed to brushing in a brushing machine with a toothpaste/water slurry for 1 and 6 h. Twelve different toothpastes were used and also four different polishing pastes. The results were evaluated using a profilometer after 1 and 6 h of brushing (corresponding to 2000 and 12 000 double strokes, respectively). A surface roughness value (Ra-value) and also a volume loss value were calculated from the profilometer measurements. These values were then correlated to each other. An unpaired t-test for the difference in the abrasion values between the toothpastes and the abrasion values over time was used. Results. The polishing paste RDA (R) 170 yielded higher Ra-values than RDA 250 (R), both after 1 and 6 h of brushing (1.01 +/- 0.22 and 8.99 +/- 1.55 compared to 0.63 +/- 0.26 and 7.83 +/- 5.89, respectively) as well as volume loss values (3.71 +/- 0.17 and 20.20 +/- 2.41 compared to 2.15 +/- 1.41 and 14.79 +/- 11.76, respectively), thus poor correlations between the RDA and Ra and Volume loss values were shown. Among the toothpastes, Apotekets (R) showed the highest Ra value after 1 h of brushing and Pepsodent (R) whitening after 6 h of brushing. Pepsodent (R) whitening also showed the highest volume loss values, both after 1 and 6 h of brushing. Conclusion. This study emphasizes the importance of not only considering the RDA value, but also a roughness value, when describing the abrasivity of a toothpaste. Furthermore, it can be concluded that so called 'whitening' toothpastes do not necessarily have a higher abrasive effect than other toothpastes.

  • 108.
    Johansson, Arvid
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Johansson, David
    Inledande studie inför utveckling av ett virtuellt mikroskop för utbildning inom livsvetenskaperna2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Forskning med hjälp av mikroskopi har med tiden ställt mer

    specialicerade krav på utrustning som används. Utrustningen

    har blivit mer bättre men samtidigt också dyrare. En

    hög kostnad innebär att avancerad mikroskopi inte kan användas

    som ett utbildningsverktyg inom grundutbildning.

    Dagens studenter tvingas på så sätt förberedas för framtidens

    forskning genom att använda gårdagens utrustning.

    I detta arbete visar vi hur virtuell mikroskopi kan användas

    för utbildning och forskning. Virtuell mikroskopi kan

    användas som komplement, eller möjligtvis ersättning, för

    befintlig undervisning. Vi har demonstrerat detta genom

    att utveckla en pilotapplikation som simulerar de två metoderna

    FLIP och FRAP. Applikationen har utvärderats

    med hjälp av erfarna mikroskopianvändare på

     

    som har kommit med åsikter och förslag. Det har

    visat sig att virtuell mikroskopi kan användas i flera olika

    syften. Som ett pedagogiskt verktyg kan det användas som

    ett träningsredskap både för mikroskophandhavande och

    för att lära sig plattformen Endrov. För att utveckla en

    tillfredsställande simulation av ett prov, så väl som abberationer

    i det optiska systemet, är det viktigt att skapa en

    god balans mellan ett trovärdigt visuellt uppträdande och

    en hög nivå av interaktion med systemet. Därav nödvändigheten

    att implementera optimerade algoritmer. Särskilt

    diffusionen av proteiner i en cell kräver beräkningskraft.

    ”Ni har övertygat mig om användbarheten med

    detta virtuella mikroskop. Jag hoppas att det

    kommer att användas i utbildningssyfte.”

    Kommentar från deltagare

    i mikroskopienkät

     

    Karolinska

     

     

    institutet

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 109. Johansson, Arvid
    et al.
    Johansson, David
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Inledande studie inför utveckling av ett virtuelltmikroskop för utbildning inom livsvetenskaperna2010Självständigt arbete på avancerad nivå (yrkesexamen), 30 poäng / 45 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Forskning med hjälp av mikroskopi har med tiden ställt mer

    specialicerade krav på utrustning som används. Utrustningen

    har blivit mer bättre men samtidigt också dyrare. En

    hög kostnad innebär att avancerad mikroskopi inte kan användas

    som ett utbildningsverktyg inom grundutbildning.

    Dagens studenter tvingas på så sätt förberedas för framtidens

    forskning genom att använda gårdagens utrustning.

    I detta arbete visar vi hur virtuell mikroskopi kan användas

    för utbildning och forskning. Virtuell mikroskopi kan

    användas som komplement, eller möjligtvis ersättning, för

    befintlig undervisning. Vi har demonstrerat detta genom

    att utveckla en pilotapplikation som simulerar de två metoderna

    FLIP och FRAP. Applikationen har utvärderats

    med hjälp av erfarna mikroskopianvändare på

     

    som har kommit med åsikter och förslag. Det har

    visat sig att virtuell mikroskopi kan användas i flera olika

    syften. Som ett pedagogiskt verktyg kan det användas som

    ett träningsredskap både för mikroskophandhavande och

    för att lära sig plattformen Endrov. För att utveckla en

    tillfredsställande simulation av ett prov, så väl som abberationer

    i det optiska systemet, är det viktigt att skapa en

    god balans mellan ett trovärdigt visuellt uppträdande och

    en hög nivå av interaktion med systemet. Därav nödvändigheten

    att implementera optimerade algoritmer. Särskilt

    diffusionen av proteiner i en cell kräver beräkningskraft.

    ”Ni har övertygat mig om användbarheten med

    detta virtuella mikroskop. Jag hoppas att det

    kommer att användas i utbildningssyfte.”

    Kommentar från deltagare

    i mikroskopienkät

     

    Karolinska

     

     

    institutet

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 110. Johansson, Bjoern
    et al.
    Sundelin, Staffan
    Wikberg-Matsson, Anna
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Behndig, Anders
    Visual and optical performance of the akreos adapt advanced optics and tecnis Z9000 intraocular lenses - Swedish multicenter study2007Ingår i: Journal of cataract and refractive surgery, ISSN 0886-3350, E-ISSN 1873-4502, Vol. 33, nr 9, s. 1565-1572Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE: To compare the subjective visual and objective optical performance of 2 aspherical intraocular lenses (IOLs), the Akreos Adapt Advanced Optics (AO) (Bausch & Lomb, Inc.) and the Tecnis Z9000 (Advanced Medical Optics, Inc.). SETTING: Four university hospitals in Sweden. METHODS: This study comprised 80 patients, 20 each from 4 university hospital centers in Sweden. All patients had bilateral clear corneal phacoemulsification with implantation of an Akreos Adapt AO IOL in 1 eye and Tecnis Z9000 IOL in the other eye according to a randomization protocol. Preoperatively, 90% contrast Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity was measured and the mesopic pupil sizes were determined. Ten to 12 weeks postoperatively, 12.5% and 90% contrast ETDRS visual acuities and photopic and mesopic Functional Acuity Contrast Test chart contrast sensitivities were determined. Wavefront analysis was performed with the Zywave 11 aberrometer (Bausch & Lomb, Inc.), and a questionnaire on the subjective quality of vision was completed by each patient. RESULTS: The Akreos AD IOL and Tecnis Z9000 IOL produced similar high- and low-contrast visual acuities as well as photopic and mesopic contrast sensitivities. The Tecnis Z9000 IOL resulted in lower spherical aberrations of the eye (mean 0.05 +/- 0.13 pm versus 0.35 +/- 0.13 mu m root mean square, 6.0 mm pupil) (P<.001); however, the Akreos AO IOL provided a larger depth of field (mean 1.22 diopter [D] +/- 0.48 [SD] versus 0.86 +/- 0.50 D, 6.0 mm pupil) (P<.001). Patient satisfaction was generally high, although 68.8% of the patients reported some type of visual disturbance postoperatively. Twenty-eight percent of patients reported better subjective visual quality in the Akreos AD eye and 14%, in the Tecnis Z9000 eye (P<.0001). Accordingly, 33% perceived more visual disturbances in the Tecnis Z9000 eye and 11%, in the Akreos AID eye (P<.0001). CONCLUSIONS: Maximum reduction of spherical aberration did not maximize subjective visual quality. The higher perceived quality of vision with the Akreos AD IOL could be because of differences in depth of field, IOL material, or IOL design.

  • 111.
    Johansson, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Enlund, J.
    Johansson, S.
    Katardjiev, I.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Yantchev, V.
    Surface acoustic wave-induced precise particle manipulation in a trapezoidal glass microfluidic channel2012Ingår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, nr 2, s. 025018-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface acoustic wave (SAW) excitation of an acoustic field in a trapezoidal glass microfluidic channel for particle manipulation in continuous flow has been demonstrated. A unidirectional interdigital transducer (IDT) on a Y-cut Z-propagation lithium niobate (LiNbO3) substrate was used to excite a surface acoustic wave at approximately 35 MHz. An SU8 layer was used for adhesive bonding of the superstrate glass layer and the substrate piezoelectric layer. This work extends the use of SAWs for acoustic manipulation to also include glass channels in addition to prior work with mainly poly-di-methyl-siloxane channels. Efficient alignment of 1.9 mu m polystyrene particles to narrow nodal regions was successfully demonstrated. In addition, particle alignment with only one IDT active was realized. A finite element method simulation was used to visualize the acoustic field generated in the channel and the possibility of 2D alignment into small nodal regions was demonstrated.

  • 112. Johansson, Ulf
    et al.
    Vogt, Ulrich
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Mikkelsen, Anders
    NanoMAX: a hard x-ray nanoprobe beamline at MAX IV2013Ingår i: SPIE Optical Engineering+ Applications, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    We describe the design of the NanoMAX beamline to be built among the first phase beamlines of the MAX IV facility inLund, Sweden. NanoMAX will be a hard X-ray imaging beamline providing down to 10 nm in direct spatial resolution,enabling investigations of very small heterogeneous samples exploring methods of diffraction, scattering, absorption,phase contrast and fluorescence. The beamline will have two experimental stations using Fresnel zone plates andKirkpatrick-Baez mirror optics for beam focusing, respectively. This paper focuses on the optical design of the beamlineexcluding the experimental stations but also describes general ideas about the endstations and the nano-focusing optics tobe used. The NanoMAX beamline is planned to be operational late 2016.

  • 113. Kang, G.
    et al.
    Rahomäki, Jussi
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Dong, J.
    Honkanen, S.
    Turunen, J.
    Enhanced deep ultraviolet inverse polarization transmission through hybrid Al-SiO2 gratings2013Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, nr 13, s. 131110-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on the enhancement of inverse polarization transmission of deep ultraviolet light, with the TE transmittance ηTE largely exceeding the TM transmittance ηTM, through a hybrid Al-SiO 2 grating: The grating slits are conformally filled with SiO 2. Strong coupling of the incident wave to surface plasmon polaritons greatly reduces the TM transmittance, whereas the coupling to the low-loss TE mode, with its effective refractive index approaching that of the substrate, leads to the enhanced TE transmittance. At resonance, a pronounced inverse polarization extinction ratio of 35 dB was obtained in our experiment, much higher than any previously reported values.

  • 114. Kertmen, Ahmet
    et al.
    Torruella, Pau
    Coy, Emerson
    Yate, Luis
    Nowaczyk, Grzegorz
    Gapinski, Jacek
    Vogt, Carmen
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Toprak, Muhammet
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Estrade, Sonia
    Peiro, Francesca
    Milewski, Slawomir
    Jurga, Stefan
    Andruszkiewicz, Ryszard
    Acetate-Induced Disassembly of Spherical Iron Oxide Nanoparticle Clusters into Monodispersed Core-Shell Structures upon Nanoemulsion Fusion2017Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 33, nr 39, s. 10351-10365Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It has been long known that the physical encapsulation of oleic acid-capped iron oxide nanoparticles (OA-IONPs) with the cetyltrimethylammonium (CTA(+)) surfactant induces the formation of spherical iron oxide nanoparticle clusters (IONPCs). However, the behavior and functional properties of IONPCs in chemical reactions have been largely neglected and are still not well-understood. Herein, we report an unconventional ligand-exchange function of IONPCs activated when dispersed in an ethyl acetate/acetate buffer system. The ligand exchange can successfully transform hydrophobic OA-IONP building blocks of IONPCs into highly hydrophilic, acetate-capped iron oxide nanoparticles (Ac-IONPs). More importantly, we demonstrate that the addition of silica precursors (tetraethyl orthosilicate and 3-aminopropyltriethoxysilane) to the acetate/oleate ligand-exchange reaction of the IONPs induces the disassembly of the IONPCs into monodispersed iron oxide-acetate-silica core-shell-shell (IONPs@acetate@SiO2) nanoparticles. Our observations evidence that the formation of IONPs@acetate@SiO2 nanoparticles is initiated by a unique micellar fusion mechanism between the Pickering-type emulsions of IONPCs and nanoemulsions of silica precursors formed under ethyl acetate buffered conditions. A dynamic rearrangement of the CTA(+)-oleate bilayer on the IONPC surfaces is proposed to be responsible for the templating process of the silica shells around the individual IONPs. In comparison to previously reported methods in the literature, our work provides a much more detailed experimental evidence of the silica-coating mechanism in a nanoemulsion system. Overall, ethyl acetate is proven to be a very efficient agent for an effortless preparation of monodispersed IONPs@acetate@SiO2 and hydrophilic Ac-IONPs from IONPCs.

  • 115.
    Khachatourian, Malek Adrine
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik. Iran University of Science and Technology, Iran.
    Golestani-Fard, F.
    Sarpoolaky, H.
    Vogt, Carmen
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vasileva, Elena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Mensi, Mounir
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Microwave synthesis of Y2O3:Eu3+ nanophosphors: A study on the influence of dopant concentration and calcination temperature on structural and photoluminescence properties2016Ingår i: Journal of Luminescence, ISSN 0022-2313, E-ISSN 1872-7883, Vol. 169, s. 1-8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Red fluorescent emitting monodispersed spherical Y<inf>2</inf>O<inf>3</inf> nanophosphors with different Eu3+ doping concentrations (0-13 mol%) are synthesized by a novel microwave assisted urea precipitation, which is recognized as a green, fast and reproducible synthesis method. The effect of Eu3+ doping and calcination temperature on the structural characteristics and luminescence properties of particles is investigated in detail. The as prepared powders have (Y,Eu)(OH)(CO<inf>3</inf>) structure which converts to Y<inf>2</inf>O<inf>3</inf>:Eu3+ from 500 °C and become crystalline at higher temperatures. The crystallite size of nanophosphors increased from 15 nm to 25 nm as the calcination temperature increased from 700 °C to 1050 °C. The efficient incorporation of Eu3+ ions in cubic Y<inf>2</inf>O<inf>3</inf> host matrix is confirmed by the calculated X-ray Powder diffraction (XRPD) structural parameters. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs show that the as obtained and calcined particles are spherical, monodispersed and non-agglomerated. The overall size of particles increases from 61±8 nm to 86±9 nm by increasing Eu3+ concentration from 0 mol% to 13 mol%. High resolution TEM revealed polycrystalline nature of calcined particles. The particles exhibit a strong red emission under ultraviolet (UV) excitation. The photoluminescence (PL) intensity of the peaks increases proportionally with Eu3+ concentration and the calcination temperature with no luminescence quenching phenomenon observed even for Y<inf>2</inf>O<inf>3</inf>:13%Eu3+. The fluorescent emission properties combined with the monodispersity and narrow size distribution characteristics make the Y<inf>2</inf>O<inf>3</inf>:Eu3+ heavy metal free nanophosphors applicable in fluorescence cell imaging and as fluorescence biolabels.

  • 116.
    Khachatourian, Malek Adrine
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik. IUST-Iran University of Science and Technology, Iran.
    Golestani-Fard, F.
    Sarpoolaky, H.
    Vogt, Carmen
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Zhao, Yichen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Green synthesis of Y2O3:Eu3+ nanocrystals for bioimaging2015Ingår i: Materials Research Society Symposium Proceedings, Materials Research Society, 2015, Vol. 1720, s. 59-64Konferensbidrag (Refereegranskat)
    Abstract [en]

    Rare earth (e.g., Eu, Er, Yb, Tm) doped Y<inf>2</inf>O<inf>3</inf> nanocrystals are promising fluorescent bioimaging agents which can overcome well known problems of currently used organic dyes like photobleaching, phototoxicity, and light scattering. Furthermore, the alternative quantum dots (QDs) composed of heavy metals (e.g., CdSe) possess inherently low biocompatibility due to the heavy metal content. In the present work, monodisperse spherical Y<inf>2</inf>O<inf>3</inf>:Eu3+ nanocrystals were successfully synthesized by microwave assisted urea precipitation method followed by thermochemical treatment. This is a green, fast and reproducible synthesis method, which is surfactant and hazardous precursors free. The as prepared particles were non-aggregated, spherical particles with a narrow size distribution. The calcined particles have a polycrystalline structure preserving the monodispersity and the spherical morphology of the as prepared particles. After calcination of Y(OH)CO<inf>3</inf>:Eu3+ precursors at 900°C for 2 hours, a highly crystalline cubic Y<inf>2</inf>O<inf>3</inf> structure was obtained. The Y<inf>2</inf>O<inf>3</inf>:Eu3+ spherical particles showed a strong red emission peak at 613nm due to the 5D<inf>0</inf>-7F<inf>2</inf> forced electric dipole transition of Eu3+ ions under UV excitation (235 nm) as revealed by the photoluminescence analysis (PL). The effect of reaction time on size and photoluminescence properties of calcined particles and also the effect of reaction temperature and pressure on the size and the yield of the precipitation process have been studied. The intense red fluorescent emission, excellent stability and potential low toxicity make these QDs promising for applications in bio-related areas such as fluorescence cell imaging or fluorescence bio labels.

  • 117.
    Khalil, Alaa
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Mechanical Engineering Department, Canadian International College, Fifth Settlement, New Cairo, Egypt.
    Nasser, W. S.
    Osman, T. A.
    Toprak, Muhammet Sadaka
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Muhammed, Mamoun
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Uheida, Abdusalam
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Surface modified of polyacrylonitrile nanofibers by TiO2/MWCNT for photodegradation of organic dyes and pharmaceutical drugs under visible light irradiation2019Ingår i: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 179, artikel-id 108788Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work describes the fabrication of two composite nanofibers systems containing polyacrylonitrile polymer (PAN), Multiwall carbon nanotubes (MWCNT) and Titania (TiO2) nanoparticles. Photodegradation experiments were performed to study the effect of various parameters including pH, catalyst dose, pollutant concentration and reaction time for three model compounds, methylene blue (MB), indigo carmine (IC), and ibuprofen (IBU) under visible light. Morphology and structure of the modified composite nanofibers were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA), Photoluminescence (PL) spectroscopy, Raman spectra, and X-ray Photoelectron Spectra (XPS) analyses. The photocatalytic performance was achieved in a rather short time visible light (&lt;30 min) and under low power intensity (125 W) compared to earlier reports. Kinetics data fitted well using pseudo-first order model to describe the mechanism of photocatalytic degradation processes. The stability and flexibility of the fabricated composite nanofibers allow their application in a continuous flow system and their re-use after several cycles.

  • 118. Kim, Kyung Hwan
    et al.
    Pathak, Harshad
    Spah, Alexander
    Perakis, Fivos
    Mariedahl, Daniel
    Sellberg, Jonas A.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Katayama, Tetsuo
    Harada, Yoshihisa
    Ogasawara, Hirohito
    Pettersson, Lars G. M.
    Nilsson, Anders
    Temperature-Independent Nuclear Quantum Effects on the Structure of Water2017Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 119, nr 7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nuclear quantum effects (NQEs) have a significant influence on the hydrogen bonds in water and aqueous solutions and have thus been the topic of extensive studies. However, the microscopic origin and the corresponding temperature dependence of NQEs have been elusive and still remain the subject of ongoing discussion. Previous x-ray scattering investigations indicate that NQEs on the structure of water exhibit significant temperature dependence [Phys. Rev. Lett. 94, 047801 (2005)]. Here, by performing wide-angle x-ray scattering of H2O and D2O droplets at temperatures from 275 K down to 240 K, we determine the temperature dependence of NQEs on the structure of water down to the deeply supercooled regime. The data reveal that the magnitude of NQEs on the structure of water is temperature independent, as the structure factor of D2O is similar to H2O if the temperature is shifted by a constant 5 K, valid from ambient conditions to the deeply supercooled regime. Analysis of the accelerated growth of tetrahedral structures in supercooled H2O and D2O also shows similar behavior with a clear 5 K shift. The results indicate a constant compensation between NQEs delocalizing the proton in the librational motion away from the bond and in the OH stretch vibrational modes along the bond. This is consistent with the fact that only the vibrational ground state is populated at ambient and supercooled conditions.

  • 119. Kim, Kyung Hwan
    et al.
    Spah, Alexander
    Pathak, Harshad
    Perakis, Fivos
    Mariedahl, Daniel
    Amann-Winkel, Katrin
    Sellberg, Jonas A.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Lee, Jae Hyuk
    Kim, Sangsoo
    Park, Jaehyun
    Nam, Ki Hyun
    Katayama, Tetsuo
    Nilsson, Anders
    Maxima in the thermodynamic response and correlation functions of deeply supercooled water2017Ingår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 358, nr 6370Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Femtosecond x-ray laser pulses were used to probe micrometer-sized water droplets that were cooled down to 227 kelvin in vacuum. Isothermal compressibility and correlation length were extracted from x-ray scattering at the low-momentum transfer region. The temperature dependence of these thermodynamic response and correlation functions shows maxima at 229 kelvin for water and 233 kelvin for heavy water. In addition, we observed that the liquids undergo the fastest growth of tetrahedral structures at similar temperatures. These observations point to the existence of a Widom line, defined as the locus of maximum correlation length emanating from a critical point at positive pressures in the deeply supercooled regime. The difference in the maximum value of the isothermal compressibility between the two isotopes shows the importance of nuclear quantum effects.

  • 120.
    Kim, Kyung Hwan
    et al.
    Stockholm Univ, Albanova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Spah, Alexander
    Stockholm Univ, Albanova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Pathak, Harshad
    Stockholm Univ, Albanova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Perakis, Fivos
    Stockholm Univ, Albanova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Mariedahl, Daniel
    Stockholm Univ, Albanova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Amann-Winkel, Katrin
    Stockholm Univ, Albanova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Sellberg, Jonas A.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Lee, Jae Hyuk
    Pohang Accelerator Lab, Pohang 37673, Gyeongbuk, South Korea..
    Kim, Sangsoo
    Pohang Accelerator Lab, Pohang 37673, Gyeongbuk, South Korea..
    Park, Jaehyun
    Pohang Accelerator Lab, Pohang 37673, Gyeongbuk, South Korea..
    Nam, Ki Hyun
    Pohang Accelerator Lab, Pohang 37673, Gyeongbuk, South Korea..
    Katayama, Tetsuo
    Japan Synchrotron Radiat Res Inst, Kouto 1-1-1, Sayo, Hyogo 6795198, Japan..
    Nilsson, Anders
    Stockholm Univ, Albanova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Response to Comment on "Maxima in the thermodynamic response and correlation functions of deeply supercooled water"2018Ingår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 360, nr 6390, artikel-id eaat1729Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Caupin et al. have raised several issues regarding our recent paper on maxima in thermodynamic response and correlation functions in deeply supercooled water. We show that these issues can be addressed without affecting the conclusion of the paper.

  • 121.
    Kothapalli, Satya V. V. N.
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Janerot-Sjöberg, Birgitta
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik. Karolinska Institute, Sweden; Karolinska University Hospital, Sweden.
    Paradossi, Gaio
    Grishenkov, Dmitry
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik. Karolinska Institute, Sweden; Karolinska University Hospital, Sweden.
    Investigation of polymer-shelled microbubble motions in acoustophoresis2016Ingår i: Ultrasonics, ISSN 0041-624X, E-ISSN 1874-9968, Vol. 70, s. 275-283Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of this paper is to explore the trajectory motion of microsize (typically smaller than a red blood cell) encapsulated polymer-shelled gas bubbles propelled by radiation force in an acoustic standing-wave field and to compare the corresponding movements of solid polymer microbeads. The experimental setup consists of a microfluidic chip coupled to a piezoelectric crystal (PZT) with a resonance frequency of about 2.8 MHz. The microfluidic channel consists of a rectangular chamber with a width, w, corresponding to one wavelength of the ultrasound standing wave. It creates one full wave ultrasound of a standing-wave pattern with two pressure nodes at w/4 and 3w/4 and three antinodes at 0, w/2, and w. The peak-to-peak amplitude of the electrical potential over the PZT was varied between 1 and 10 V. The study is limited to no-flow condition. From Gor'kov's potential equation, the acoustic contrast factor, Phi, for the polymer-shelled microbubbles was calculated to about -60.7. Experimental results demonstrate that the polymer-shelled microbubbles are translated and accumulated at the pressure antinode planes. This trajectory motion of polymer-shelled microbubbles toward the pressure antinode plane is similar to what has been described for other acoustic contrast particles with a negative Phi. First, primary radiation forces dragged the polymer-shelled microbubbles into proximity with each other at the pressure antinode planes. Then, primary and secondary radiation forces caused them to quickly aggregate at different spots along the channel. The relocation time for polymer-shelled microbubbles was 40 times shorter than that for polymer microbeads, and in contrast to polymer microbeads, the polymer-shelled microbubbles were actuated even at driving voltages (proportional to radiation forces) as low as 1 V. In short, the polymer-shelled microbubbles demonstrate the behavior attributed to the negative acoustic contrast factor particles and thus can be trapped at the antinode plane and thereby separated from particles having a positive acoustic contrast factor, such as for example solid particles and cells. This phenomenon could be utilized in exploring future applications, such as bioassay, bioaffinity, and cell interaction studies in vitro in a well-controlled environment.

  • 122. Kurta, Ruslan P.
    et al.
    Donatelli, Jeffrey J.
    Yoon, Chun Hong
    Berntsen, Peter
    Bielecki, Johan
    Daurer, Benedikt J.
    DeMirci, Hasan
    Fromme, Petra
    Hantke, Max Felix
    Maia, Filipe R. N. C.
    Munke, Anna
    Nettelblad, Carl
    Pande, Kanupriya
    Reddy, Hemanth K. N.
    Sellberg, Jonas A.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Sierra, Raymond G.
    Svenda, Martin
    van der Schot, Gijs
    Vartanyants, Ivan A.
    Williams, Garth J.
    Xavier, P. Lourdu
    Aquila, Andrew
    Zwart, Peter H.
    Mancuso, Adrian P.
    Correlations in Scattered X-Ray Laser Pulses Reveal Nanoscale Structural Features of Viruses2017Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 119, nr 15, artikel-id 158102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use extremely bright and ultrashort pulses from an x-ray free-electron laser (XFEL) to measure correlations in x rays scattered from individual bioparticles. This allows us to go beyond the traditional crystallography and single-particle imaging approaches for structure investigations. We employ angular correlations to recover the three-dimensional (3D) structure of nanoscale viruses from x-ray diffraction data measured at the Linac Coherent Light Source. Correlations provide us with a comprehensive structural fingerprint of a 3D virus, which we use both for model-based and ab initio structure recovery. The analyses reveal a clear indication that the structure of the viruses deviates from the expected perfect icosahedral symmetry. Our results anticipate exciting opportunities for XFEL studies of the structure and dynamics of nanoscale objects by means of angular correlations.

  • 123.
    Kördel, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Biological Laboratory X-Ray Microscopy2020Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Röntgenmikroskopi i vattenfönstret (𝜆 ≈ 2.3−4.3 nm) är en kraftfull metodför högupplöst biologisk avbildning. Den naturligt höga kontrasten mellankolbaserade strukturer och vatten möjliggör visualisering av prover i ettnästintill opåverkat tillstånd, och ger samtidigt tillräcklig transmission genomupp till ∼ 10 μm organisk materia. Teknikens fulla potential utnyttjasvidare genom datortomografi, vilket resulterar i en fullständig 3D-bild avobjektet.Röntgenmikroskopi i vattenfönstret, av celler och vävnad och med kortexponeringstid, utförs rutinmässigt vid synkrotronljuskällor runt om i världen,men med begränsad tillgänglighet för forskarsamfundet. Av den anledningenhar laboratoriebaserade system utvecklats, vilka nu börjar nåmognad. Fördelarna jämfört med synkrotronbaserade instrument består avenklare integrering av komplementära laboratoriemetoder, utöver den utökadetillgängligheten som tillåter tidskrävande optimering av experimentellaparametrar såväl som longitudinella studier.Denna avhandling beskriver nyligen utfört arbete för att förbättra detkompakta mjukröntgenmikroskopet i Stockholm, samt flera biologiskatillämpningar. Arbete har gjorts för att förbättra mikroskopets mekaniskaoch termiska stabilitet, vilket har resulterat i 25 nm upplösning (halvperiod) i bilder av teststrukturer. De biologiska tillämpningarna harmöjliggjorts av en markant ökad röntgenintensitet vid provet, såväl somförbättrad driftsstabilitet. Resultaten som presenteras består, bland annat,av avbildning av kryofixerade hela celler med 10-sekundersexponeringar,avbildning av virusinfektioner i celler och kryotomografi med 20 minuterstotal exponeringtid.

    Ladda ner fulltext (pdf)
    Kördel_thesis_2020
  • 124.
    Kördel, Mikael
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Arsana, Komang Gede Yudi
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Ulrich
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Stability investigation of a cryo soft x-ray microscope by fiber interferometry2020Ingår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 91, nr 2, artikel-id 023701Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a stability investigation of the Stockholm laboratory cryo soft x-ray microscope. The microscope operates at a wavelength of 2.48 nm and can image biological samples at liquid-nitrogen temperatures in order to mitigate radiation damage. We measured the stability of the two most critical components, sample holder and optics holder, in vacuo and at cryo temperatures at both short and long time scales with a fiber interferometer. Results revealed vibrations in the kHz range, originating mainly from a turbo pump, as well as long term drifts in connection with temperature fluctuations. With improvements in the microscope, earlier stability issues vanished and close-to diffraction-limited imaging could be achieved. Moreover, our investigation shows that fiber interferometers are a powerful tool in order to investigate position-sensitive setups at the nanometer level.

  • 125.
    Kördel, Mikael
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Dehlinger, Aurelie
    Technische Universität Berlin.
    Seim, Christian
    Technische Universität Berlin.
    Vogt, Ulrich
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Fogelqvist, Emelie
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Sellberg, Jonas A.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Stiel, Holger
    Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Berlin.
    Hertz, Hans
    KTH, Tidigare Institutioner (före 2005), Fysik. KTH, Skolan för teknikvetenskap (SCI), Fysik. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Laboratory water-window x-ray microscopyManuskript (preprint) (Övrigt vetenskapligt)
  • 126.
    Kördel, Mikael
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Fogelqvist, Emelie
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Carannante, Valentina
    Department of Microbiology, Karolinska Institutet.
    Önfelt, Björn
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Reddy, Hemanth K. N.
    Department of Cell and Molecular Biology, Uppsala University.
    Okamoto, Kenta
    Department of Cell and Molecular Biology, Uppsala University.
    Svenda, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Sellberg, Jonas A.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans
    KTH, Tidigare Institutioner (före 2005), Fysik. KTH, Skolan för teknikvetenskap (SCI), Fysik. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Biological Laboratory X-ray Microscopy2018Ingår i: Microscopy and Microanalysis, Vol. 24, nr S2, s. 346-347Artikel i tidskrift (Refereegranskat)
  • 127.
    Kördel, Mikael
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Fogelqvist, Emelie
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Carannante, Valentina
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, S-17177 Solna, Sweden..
    Önfelt, Björn
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Reddy, Hemanth K. N.
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, S-75124 Uppsala, Sweden..
    Svenda, Martin
    Uppsala Univ, Dept Cell & Mol Biol, Lab Mol Biophys, S-75124 Uppsala, Sweden..
    Sellberg, Jonas A.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Arsana, Komang G.Y.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Ulrich
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Biological Laboratory X-Ray Microscopy2019Ingår i: X-Ray Nanoimaging: Instruments and Methods IV / [ed] Lai, B Somogyi, A, SPIE - International Society for Optical Engineering, 2019, Vol. 11112, artikel-id 111120TKonferensbidrag (Refereegranskat)
    Abstract [en]

    Zone-plate-based soft x-ray microscopes operating in the water window allow high-resolution and high-contrast imaging of intact cells in their near-native state. Laboratory-source-based x-ray microscopes are an important complement to the accelerator-based instruments, providing high accessibility and allowing close integration with other cell-biological techniques. Here we present recent biological applications using the Stockholm laboratory water-window x-ray microscope, which is based on a liquid-nitrogen-jet laser-plasma source. Technical improvements to the microscope in the last few years have resulted in increased x-ray flux at the sample and significantly improved stability and reliability. In addition to this, vibrations in key components have been measured, analyzed and reduced to improve the resolution to 25 nm half-period. The biological applications include monitoring the development of carbon-dense vesicles in starving human embryonic kidney cells (HEK293T), imaging the interaction between natural killer (NK) cells and HEK293T target cells, and most recently studying a newly discovered giant DNA virus and the process of viral replication inside a host amoeba. All biological imaging was done on cryo-frozen hydrated samples in 2D and in some cases 3D.

  • 128.
    Kördel, Mikael
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Svenda, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Reddy, Hemanth K. N.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik. Department of Cell and Molecular Biology, Uppsala University.
    Fogelqvist, Emelie
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hamawandi, Bejan
    KTH.
    Toprak, Muhammet
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. KTH, Tidigare Institutioner (före 2005), Materialvetenskap. KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik. KTH, Tidigare Institutioner (före 2005), Fysik. KTH, Skolan för teknikvetenskap (SCI), Fysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Sellberg, Jonas A.
    KTH, Tidigare Institutioner (före 2005), Fysik. KTH, Skolan för teknikvetenskap (SCI), Fysik. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Quantitative bioconversion in giant DNA virus infectionManuskript (preprint) (Övrigt vetenskapligt)
  • 129. Lakshminarayanan, Vasudevan
    et al.
    Varadharajan, L. Srinivasa
    Diaz-Santana, Luis
    Lundström, Linda
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vision Science and Ophthalmic Optics2011Ingår i: Journal of Modern Optics, ISSN 0950-0340, E-ISSN 1362-3044, Vol. 58, nr 19-20, s. 1679-1680Artikel i tidskrift (Övrigt vetenskapligt)
  • 130.
    Larsson, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Small-Animal Imaging with Liquid-Metal-Jet X-Ray Sources2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Röntgenavbildning av små försöksdjur är en viktig metod inom medicinsk forskning. Röntgenstrålar penetrerar material, vilket gör det möjligt att undersöka 3D-strukturen hos försöksdjur och andra tjocka biologiska prov med hjälp av datortomografi (CT). Tyvärr kräver smådjursavbildning ofta dels hög upplösning, eftersom de relevanta strukturerna är små, dels korta exponeringstider, eftersom objektet tenderar att röra sig. Detta är en utmaning, då båda egenskaperna kräver kompakta röntgenkällor med speciella egenskaper som inte är brett tillgängliga.

    I denna avhandling visar vi den första användningen av metallstråleröntgenkällor för avbildning av hela smådjur. Den här typen av röntgenkälla uppfanns vid KTH för drygt tio år sedan. Genom att låta elektronerna träffa en stråle av flytande metall, istället för en solid metallanod, kan vi generera mer röntgenstrålning men samtidigt behålla en liten källpunkt, vilket behövs för avbildning med hög upplösning. En ny metallstrålekälla utvecklades som en del av denna avhandling. Den ger ett röntgenspektrum med högre energier, vilket gör källan mer lämpad än tidigare källor för avbildning av små försöksdjur och andra centimetertjocka biologiska objekt.

    Vi har använt metallstrålekällor för att avbilda intakta, avlivade möss och zebrafiskar. Med högupplöst absorptions-CT har vi detekterat små bendetaljer inuti möss. Vi har även använt faskontrastavbildning, en ny metod som avsevärt kan förbättra avbildning av mjukvävnad, till att demarkera millimeterstora tumörer inuti en hel mus, samt för avbildning av brosk i leder hos möss. Faskontrast ger en kraftig förstärkning av kontrasten i bilden, vilket även har använts för att för första gången detektera individuella muskelfibrer (och eventuellt även myofibriller) inuti zebrafiskar med en kompakt röntgenkälla. Muskelstrukturerna har diametrar på 5-7 μm och låg kontrast, vilket gör dem svåra att observera.

    Med hjälp av faskontrast har vi utvecklat en metod för att avbilda blodkärl med diametrar under 10 μm inuti organ och vävnader från möss och råttor ex vivo, med stråldoser som är kompatibla med studier av levande smådjur. Detta är inte möjligt med konventionell absorptionskontrast och jod-baserade kontrastmedel. Vi har dessutom avbildat nyformade blodkärl kring tumörer i musöron och observerat kärlens kaotiska struktur.

    Slutligen presenterar vi de första resultaten från en prototyp av en ny högeffektskälla. Källan har tio gånger högre effekt än tidigare metallstrålekällor, men bibehåller samma storlek på källpunkten. Den här högeffektskällan är ett viktigt steg mot framtida laboratoriebaserad avbildning av levande små försöksdjur med hög upplösning.

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    Thesis
  • 131.
    Larsson, Daniel H.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Lundström, Ulf
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Westermark, U.
    Takman, Per
    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, M.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Small-animal tomography with a liquid-metal-jet x-ray source2012Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2012, Vol. 8313, s. 83130N-Konferensbidrag (Refereegranskat)
    Abstract [en]

    X-ray tomography of small animals is an important tool for medical research. For high-resolution x-ray imaging of few-cm-thick samples such as, e.g., mice, high-brightness x-ray sources with energies in the few-10-keV range are required. In this paper we perform the first small-animal imaging and tomography experiments using liquid-metal-jet-anode x-ray sources. This type of source shows promise to increase the brightness of microfocus x-ray systems, but present sources are typically optimized for an energy of 9 keV. Here we describe the details of a high-brightness 24-keV electron-impact laboratory microfocus x-ray source based on continuous operation of a heated liquid-In/Ga-jet anode. The source normally operates with 40 W of electron-beam power focused onto the metal jet, producing a 7×7 μm 2 FWHM x-ray spot. The peak spectral brightness is 4 × 10 9 photons/( s × mm 2 × mrad 2 × 0.1%BW) at the 24.2 keV In K α line. We use the new In/Ga source and an existing Ga/In/Sn source for high-resolution imaging and tomography of mice.

  • 132.
    Larsson, Daniel H.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Lundström, Ulf
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Westermark, Ulrica K.
    Arsenian Henriksson, Marie
    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.
    First application of liquid-metal-jet sources for small-animal imaging: High-resolution CT and phase-contrast tumor demarcation2013Ingår i: Medical physics (Lancaster), ISSN 0094-2405, Vol. 40, nr 2, s. 021909-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: Small-animal studies require images with high spatial resolution and high contrast due to the small scale of the structures. X-ray imaging systems for small animals are often limited by the microfocus source. Here, the authors investigate the applicability of liquid-metal-jet x-ray sources for such high-resolution small-animal imaging, both in tomography based on absorption and in soft-tissue tumor imaging based on in-line phase contrast. Methods: The experimental arrangement consists of a liquid-metal-jet x-ray source, the small-animal object on a rotating stage, and an imaging detector. The source-to-object and object-to-detector distances are adjusted for the preferred contrast mechanism. Two different liquid-metal-jet sources are used, one circulating a Ga/In/Sn alloy and the other an In/Ga alloy for higher penetration through thick tissue. Both sources are operated at 40-50 W electron-beam power with similar to 7 mu m x-ray spots, providing high spatial resolution in absorption imaging and high spatial coherence for the phase-contrast imaging. Results: High-resolution absorption imaging is demonstrated on mice with CT, showing 50 mu m bone details in the reconstructed slices. High-resolution phase-contrast soft-tissue imaging shows clear demarcation of mm-sized tumors at much lower dose than is required in absorption. Conclusions: This is the first application of liquid-metal-jet x-ray sources for whole-body small-animal x-ray imaging. In absorption, the method allows high-resolution tomographic skeletal imaging with potential for significantly shorter exposure times due to the power scalability of liquid-metal-jet sources. In phase contrast, the authors use a simple in-line arrangement to show distinct tumor demarcation of few-mm-sized tumors. This is, to their knowledge, the first small-animal tumor visualization with a laboratory phase-contrast system.

  • 133.
    Larsson, Daniel H.
    et al.
    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.
    Lundström, Ulf
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Burvall, Anna
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    A 24 keV liquid-metal-jet x-ray source for biomedical applications2011Ingår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 82, nr 12, s. 123701-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a high-brightness 24-keV electron-impact microfocus x-ray source based on continuous operation of a heated liquid-indium/gallium-jet anode. The 30–70 W electron beam is magnetically focused onto the jet, producing a circular 7–13 μm full width half maximum x-ray spot. The measured spectral brightness at the 24.2 keV In Kα line is 3 × 109 photons/(s × mm2 × mrad2 × 0.1% BW) at 30 W electron-beam power. The high photon energy compared to existing liquid-metal-jet sources increases the penetration depth and allows imaging of thicker samples. The applicability of the source in the biomedical field is demonstrated by high-resolution imaging of a mammography phantom and a phase-contrast angiography phantom.

  • 134.
    Larsson, Daniel H.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Stanford University, United States.
    Vågberg, William
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Yaroshenko, Andre
    Yildirim, Ali Oender
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    High-resolution short- exposure small-animal laboratory x-ray phase-contrast tomography2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikel-id 39074Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    X-ray computed tomography of small animals and their organs is an essential tool in basic and preclinical biomedical research. In both phase-contrast and absorption tomography high spatial resolution and short exposure times are of key importance. However, the observable spatial resolutions and achievable exposure times are presently limited by system parameters rather than more fundamental constraints like, e.g., dose. Here we demonstrate laboratory tomography with few-ten mu m spatial resolution and few-minute exposure time at an acceptable dose for small-animal imaging, both with absorption contrast and phase contrast. The method relies on a magnifying imaging scheme in combination with a high-power small-spot liquid-metal-jet electron-impact source. The tomographic imaging is demonstrated on intact mouse, phantoms and excised lungs, both healthy and with pulmonary emphysema.

  • 135.
    Larsson, Jakob C.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Laboratory x-ray fluorescence tomography2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Röntgenfluorescenstomografi (RFT) är en framväxande avbildningsteknik med potential för högupplöst molekylär avbildning i 3D. Den här tekniken mäter fluorescenssignalen från nanopartiklar vilket ger information om både nanopartiklarnas distribution och koncentration inuti objektet. Nuvarande kompakta system har begränsad upplösning (>1 mm), långa mättider och hög stråldos även vid höga koncentrationer av nanopartiklar, främst på grund av låg effektivitet och dåligt signal-brus-förhållande. Andra makroskopiska avbildningsmetoder ger antingen morfologisk information med hög upplösning (e.g., datortomografi) eller funktionell/molekylär information med lägre upplösning (e.g., positronemissionstomografi).

    I denna avhandling presenterar vi ett kompakt RFT-system med hög upplösning (200 μm), låg nanopartikelkoncentration och drastiskt reducerade mättider och dos, vilket öppnar upp möjligheter för in vivo-forskning på smådjur. Systemet består av en metallstrålekälla, röntgenoptik och två fotonräknande detektorer. Genom att använda källans karakteristiska emissionslinje vid 24 keV tillsammans med spektralt matchade molybden-nanopartiklar minskar bakgrunden från Comptonspridning drastiskt, vilket ökar signal-brus-förhållandet. Varje mätning ger både information om nanopartiklarnas distribution och koncentration, samt om objektets absorption. En iterativ metod används för att ge en kvantitativ rekonstruktion av röntgenfluorescensbilden. De rekonstruerade röntgenfluorescens- och absorptionsbilderna kombineras slutligen till en enda 3D-bild.

    Med det här systemet har vi demonstrerat högupplöst avbildning av både fantomer och möss vid stråldoser som är kompatibla med in vivo-avbildning av smådjur.

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    fulltext
  • 136.
    Larsson, Jakob C.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Lundström, Ulf
    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.
    Characterization of scintillator-based detectors for few-ten-keV high-spatial-resolution x-ray imaging2016Ingår i: Medical physics (Lancaster), ISSN 0094-2405, Vol. 43, nr 6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: High-spatial-resolution x-ray imaging in the few-ten-keV range is becoming increasingly important in several applications, such as small-animal imaging and phase-contrast imaging. The detector properties critically influence the quality of such imaging. Here the authors present a quantitative comparison of scintillator-based detectors for this energy range and at high spatial frequencies. Methods: The authors determine the modulation transfer function, noise power spectrum (NPS), and detective quantum efficiency for Gadox, needle CsI, and structured CsI scintillators of different thicknesses and at different photon energies. An extended analysis of the NPS allows for direct measurements of the scintillator effective absorption efficiency and effective light yield as well as providing an alternative method to assess the underlying factors behind the detector properties. Results: There is a substantial difference in performance between the scintillators depending on the imaging task but in general, the CsI based scintillators perform better than the Gadox scintillators. At low energies (16 keV), a thin needle CsI scintillator has the best performance at all frequencies. At higher energies (28-38 keV), the thicker needle CsI scintillators and the structured CsI scintillator all have very good performance. The needle CsI scintillators have higher absorption efficiencies but the structured CsI scintillator has higher resolution. Conclusions: The choice of scintillator is greatly dependent on the imaging task. The presented comparison and methodology will assist the imaging scientist in optimizing their high-resolution few-ten-keV imaging system for best performance.

  • 137.
    Larsson, Jakob C.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Shaker, Kian
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Focused anti-scatter grid for background reduction in x-ray fluorescence tomography2018Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 43, nr 11, s. 2591-2594Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    X-ray fluorescence (XRF) tomography is an emerging imaging technology with the potential for high spatial resolution molecular imaging. One of the key limitations is the background noise due to Compton scattering since it degrades the signal and limits the sensitivity. In this Letter, we present a linear focused anti-scatter grid that reduces the Compton scattering background. An anti-scatter grid was manufactured and evaluated both experimentally and theoretically with Monte Carlo simulations. The measurements showed a 31% increase in signal-to-background ratio, and simulations of an improved grid showed that this can easily be extended up to > 75%. Simulated tomographies using the improved grid show a large improvement in reconstruction quality. The anti-scatter grid will be important for in vivo XRF tomography since the background reduction allows for faster scan times, lower doses, and lower nanoparticle concentrations.

  • 138.
    Larsson, Jakob C.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Carmen
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vågberg, William
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Toprak, Muhammet
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Dzieran, Johanna
    Arsenian-Henriksson, Marie
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    High-spatial-resolution x-ray fluorescence tomography with spectrally matched nanoparticles2018Ingår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 63, s. 164001-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Present macroscopic biomedical imaging methods provide either morphology with high spatial resolution (e.g. CT) or functional/molecular information with lower resolution (e.g. PET). X-ray fluorescence (XRF) from targeted nanoparticles allows molecular or functional imaging but sensitivity has so far been insufficient resulting in low spatial resolution, despite long exposure times and high dose. In the present paper, we show that laboratory XRF tomography with metal-core nanoparticles (NPs) provides a path to functional/molecular biomedical imaging with ~100 µm resolution in living rodents. The high sensitivity and resolution rely on the combination of a high-brightness liquid-metal-jet x-ray source, pencil-beam optics, photon-counting energy-dispersive detection, and spectrally matched NPs. The method is demonstrated on mice for 3D tumor imaging via passive targeting of in-house-fabricated molybdenum NPs. Exposure times, nanoparticle dose, and radiation dose agree well with in vivo imaging.

  • 139.
    Larsson, Jakob C.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vågberg, William
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Carmen
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Lundström, Ulf
    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.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    High-spatial-resolution nanoparticle X-ray fluorescence tomography2016Ingår i: MEDICAL IMAGING 2016: PHYSICS OF MEDICAL IMAGING, 2016, artikel-id 97831VKonferensbidrag (Refereegranskat)
    Abstract [en]

    X-ray fluorescence tomography (XFCT) has potential for high-resolution 3D molecular x-ray bio-imaging. In this technique the fluorescence signal from targeted nanoparticles (NPs) is measured, providing information about the spatial distribution and concentration of the NPs inside the object. However, present laboratory XFCT systems typically have limited spatial resolution (>1 mm) and suffer from long scan times and high radiation dose even at high NP concentrations, mainly due to low efficiency and poor signal-to-noise ratio. We have developed a laboratory XFCT system with high spatial resolution (sub-100 mu m), low NP concentration and vastly decreased scan times and dose, opening up the possibilities for in-vivo small-animal imaging research. The system consists of a high-brightness liquid-metal-jet microfocus x-ray source, x-ray focusing optics and an energy-resolving photon-counting detector. By using the source's characteristic 24 keV line-emission together with carefully matched molybdenum nanoparticles the Compton background is greatly reduced, increasing the SNR. Each measurement provides information about the spatial distribution and concentration of the Mo nanoparticles. A filtered back-projection method is used to produce the final XFCT image.

  • 140. Legall, H.
    et al.
    Blobel, G.
    Stiel, H.
    Sandner, W.
    Seim, C.
    Takman, Per
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Martz, Dale H.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Selin, Mårten
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Ulrich
    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.
    Esser, D.
    Sipma, H.
    Luttmann, J.
    Höfffer, M.
    Hoffmann, H. D.
    Yulin, S.
    Feigl, T.
    Rehbein, S.
    Guttmann, P.
    Schneider, G.
    Wiesemann, U.
    Wirtz, M.
    Diete, W.
    Compact X-ray microscope for the water window based on a high brightness laser plasma source2012Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, nr 16, s. 18362-18369Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a laser plasma based x-ray microscope for the water window employing a high-average power laser system for plasma generation. At 90 W laser power a brightness of 7.4 x 10(11) photons/(s x sr x mu m(2)) was measured for the nitrogen Ly alpha line emission at 2.478 nm. Using a multilayer condenser mirror with 0.3 % reflectivity 10(6) photons/(mu m(2) x s) were obtained in the object plane. Microscopy performed at a laser power of 60 W resolves 40 nm lines with an exposure time of 60 s. The exposure time can be further reduced to 20 s by the use of new multilayer condenser optics and operating the laser at its full power of 130 W.

  • 141. Legall, H.
    et al.
    Stiel, H.
    Blobel, G.
    Seim, C.
    Baumann, J.
    Yulin, S.
    Esser, D.
    Hoefer, M.
    Wiesemann, U.
    Wirtz, M.
    Schneider, G.
    Rehbein, S.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    A compact laboratory transmission X-ray microscope for the water window2013Ingår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 463, nr 1, s. 012013-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the water window (2.2-4.4 nm) the attenuation of radiation in water is significantly smaller than in organic material. Therefore, intact biological specimen (e.g. cells) can be investigated in their natural environment. In order to make this technique accessible to users in a laboratory environment a Full-Field Laboratory Transmission X-ray Microscope (L-TXM) has been developed. The L-TXM is operated with a nitrogen laser plasma source employing an InnoSlab high power laser system for plasma generation. For microscopy the Ly α emission of highly ionized nitrogen at 2.48 nm is used. A laser plasma brightness of 5 × 1011 photons/(s × sr × μm2 in line at 2.48 nm) at a laser power of 70 W is demonstrated. In combination with a state-of-the-art Cr/V multilayer condenser mirror the sample is illuminated with 106 photons/(μm2 × s). Using objective zone plates 35-40 nm lines can be resolved with exposure times &lt; 60 s. The exposure time can be further reduced to 20 s by the use of new multilayer condenser optics and operating the laser at its full power of 130 W. These exposure times enable cryo tomography in a laboratory environment.

  • 142. Lemor, Robert
    et al.
    Günther, Christian
    Fuhr, Günther
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Metod och anordning för akustisk manipulering av partiklar, celler och virus2005Patent (Övrig (populärvetenskap, debatt, mm))
  • 143.
    Lewis, P. R.
    et al.
    Linnaeus Univ, Sch Optometry, Kalmar, Sweden..
    Rosén, Robert
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Gustafsson, J.
    Linnaeus Univ, Sch Optometry, Kalmar, Sweden..
    Carius, S.
    Linnaeus Univ, Sch Optometry, Kalmar, Sweden..
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Dynamic Visual Acuity in the Peripheral Visual Field Using Gabor Patches2010Ingår i: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 51, nr 13Artikel i tidskrift (Övrigt vetenskapligt)
  • 144. Lewis, Peter
    et al.
    Baskaran, Karthikeyan
    Rosén, Robert
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Lundström, Linda
    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
    Objectively Determined Refraction Improves Peripheral Vision2014Ingår i: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 91, nr 7, s. 740-746Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose. The purpose of this study was twofold: to verify a fast, clinically applicable method for determining off-axis refraction and to assess the impact of objectively obtained off-axis refractive correction on peripheral low-contrast visual acuity. Methods. We measured peripheral low-contrast resolution acuity with Gabor patches both with and without off-axis correction at 20 degrees in the nasal visual field of 10 emmetropic subjects; the correction was obtained using a commercial open-field Hartmann-Shack wavefront sensor, the COAS-HD VR aberrometer. Off-axis refractive errors were calculated for a 5-mm circular pupil inscribed within the elliptical wavefront by COAS using the instruments' inbuilt "Seidel sphere" method. Results. Most of the subjects had simple myopic astigmatism, at 20 degrees in the nasal visual field ranging from -1.00 to -2.00 DC, with axis orientations generally near 90 degrees. The mean uncorrected and corrected low-contrast resolution acuities for all subjects were 0.92 and 0.86 logMAR, respectively (an improvement of 0.06 logMAR). For subjects with a scalar power refractive error of 1.00 diopters or more, the average improvement was 0.1 logMAR. The observed changes in low-contrast resolution acuity were strongly correlated with off-axis astigmatism (Pearson r = 0.95; p < 0.0001), the J(180) cross-cylinder component (Pearson r = 0.82; p = 0.0034), and power scalar (Pearson r = -0.75; p = 0.0126). Conclusions. The results suggest that there are definite benefits in correcting even moderate amounts of off-axis refractive errors; in this study, as little as -1.50 DC of off-axis astigmatism gave improvements of up to a line in visual acuity. It may be even more pertinent for people who rely on optimal peripheral visual function, specifically those with central visual field loss; the use of open-field aberrometers could be clinically useful in rapidly determining off-axis refractive errors specifically for this patient group who are generally more challenging to refract.

  • 145. Lewis, Peter
    et al.
    Rosén, Robert
    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
    Resolution of static and dynamic stimuli in the peripheral visual field2011Ingår i: Vision Research, ISSN 0042-6989, E-ISSN 1878-5646, Vol. 51, nr 16, s. 1829-1834Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a clinical setting, emphasis is given to foveal visual function, and tests generally only utilize static stimuli. In this study, we measured static (SVA) and dynamic visual acuity (DVA) in the central and peripheral visual field on healthy, young emmetropic subjects using stationary and drifting Gabor patches. There were no differences between SVA and DVA in the peripheral visual field; however, SVA was superior to DVA in the fovea for both velocities tested. In addition, there was a clear naso-temporal asymmetry for both SVA and DVA for isoeccentric locations in the visual field beyond 10 degrees eccentricity. The lack of difference in visual acuity between static and dynamic stimuli found in this study may reflect the use of drift-motion as opposed to displacement motion used in previous studies.

  • 146. Lewis, Peter
    et al.
    Venkataraman, Abinaya Priya
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Lundström, Linda
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Optical correction and stimulus motion improve peripheral vision in eyes with central scotomaManuskript (preprint) (Övrigt vetenskapligt)
  • 147.
    Li, Yuyang
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Shaker, Kian
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Larsson, Jakob C.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Carmen
    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.
    Toprak, Muhammet S.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    A Library of Potential Nanoparticle Contrast Agents for X-Ray Fluorescence Tomography Bioimaging2018Ingår i: Contrast Media & Molecular Imaging, ISSN 1555-4309, E-ISSN 1555-4317, artikel-id UNSP 8174820Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanoparticles (NPs) have been used as contrast agents for several bioimaging modalities. X-ray fluorescence (XRF) tomography can provide sensitive and quantitative 3D detection of NPs. With spectrally matched NPs as contrast agents, we demonstrated earlier in a laboratory system that XRF tomography could achieve high-spatial-resolution tumor imaging in mice. Here, we present the synthesis, characterization, and evaluation of a library of NPs containing Y, Zr, Nb, Rh, and Ru that have spectrally matched K-shell absorption for the laboratory scale X-ray source. The K-shell emissions of these NPs are spectrally well separated from the X-ray probe and the Compton background, making them suitable for the lab-scale XRF tomography system. Their potential as XRF contrast agents is demonstrated successfully in a small-animal equivalent phantom, confirming the simulation results. The diversity in the NP composition provides a flexible platform for a better design and biological optimization of XRF tomography nanoprobes.

  • 148.
    Liljeborg, Anders V. G.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Tellefsen, G.
    Johannsen, G.
    The use of a profilometer for both quantitative and qualitative measurements of toothpaste abrasivity2010Ingår i: International Journal of Dental Hygiene, ISSN 1601-5029, E-ISSN 1601-5037, Vol. 8, nr 3, s. 237-243Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aim: To evaluate the abrasivity of different toothpastes both quantitatively and qualitatively with a profilometer technique and to correlate these findings to the radioactive dentin abrasivity (RDA) value. Materials and methods: Acrylic plates were exposed to brushing in a brushing machine with 11 different toothpastes. The results were evaluated using a profilometer. A surface roughness value (Ra-value), that is, a qualitative measurement, and also a volume value, that is, a quantitative measurement, were calculated from the profilometer results. These values were then correlated to each other and to the RDA-value. A comparison between RDA, Ra and volume measurements was performed using linear fitting procedure. Results: The results showed that the correlation between RDA and Ra measurements was low (R-2 = 0.04) and also that the correlation between RDA and volume measurements was low (R-2 = 0.00002). Correlation between Ra and abraded volume was high (R-2 = 0.87). Conclusions: It is important to consider not only the RDA-value when evaluating toothpaste abrasivity. From the profilometer results both a quantitative (volume) and qualitative (roughness) measurement of the abrasivity of a toothpaste can be obtained.

  • 149.
    Lindblom, Magnus
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Nanofabrication of Diffractive Soft X-ray Optics2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis summarizes the present status of the nanofabrication of diffractive optics, i.e. zone plates, and test objects for soft x-ray microscopy at KTH. The emphasis is on new and improved fabrication processes for nickel and germanium zone plates. A new concept in which nickel and germanium are combined in a zone plate is also presented. The main techniques used in the fabrication are electron beam lithography for the patterning, followed by plasma etching and electroplating for the structuring of the optical materials. The process for fabricating nickel zone plates has been significantly improved. The reproducibility of the electroplating step has been increased by the implementation of an in-situ rate measurement and an end-point detection method. We have also shown that pulse plating can be used to obtain zone plates with a uniform height profile. New plating mold materials have been introduced and electron-beam curing of the molds has been investigated and implemented to increase their mechanical stability so that pattern collapse in the electroplating step can be avoided. The introduction of cold development has improved the achievable resolution of the process. This has enabled the fabrication of zone plates with outermost zone widths down to 16 nm. The nickel process has also recently been adapted to fabrication of gold structures intended for test objects and hard x-ray zone plates. For the fabrication of germanium zone plates we developed a highly anisotropic plasma-etch process using Cl2 feed and sidewall passivation. Germanium zone plates have been fabricated with zone widths down to 30 nm. The diffraction efficiency is comparable to that of nickel zone plates, but the process does not involve electroplating and thus has for potential for highyield fabrication. The combination of nickel and germanium is a new fabrication concept that provides a means to achieve high diffraction efficiency even for thin nickel. The idea is to fabricate a nickel zone plate on a germanium film. The nickel zone plate itself is then used as etch mask for a highly selective CHF3- plasma etch into the germanium layer. Proof of principle experiments showed an efficiency increase of about a factor of two for nickel zone plates with a 50- nm nickel thickness.

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  • 150.
    Lindblom, Magnus
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Reinspach, Julia
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Bertilson, Michael
    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.
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Holmberg, Anders
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Nickel-germanium soft x-ray zone plates2009Ingår i: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 27, nr 3, s. L5-L7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents a fabrication process for soft x-ray zone plates in which nickel and germanium are combined to achieve high diffraction efficiency. A nickel zone plate is first fabricated on a germanium film and then used as a hardmask for a CHF3-plasma etch into the germanium. Zone plates with 50-60 nm nickel and 110-150 nm of germanium are presented. The measured diffraction efficiencies were 10%-11% at lambda=2.88 nm, which shows that high efficiency is possible even with thin nickel. Thus, the method has a potential for improving the efficiency of high-resolution zone plates for which the high-aspect-ratio structuring of nickel is difficult.

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