kth.sePublications
Change search
Refine search result
1234567 1 - 50 of 4487
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abdel-Rehim, Mohamed
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet.
    Pedersen-Bjergaard, S.
    Abdel-Rehim, A.
    Lucena, R.
    Moein, M. M.
    Cárdenas, S.
    Miró, M.
    Microextraction approaches for bioanalytical applications: An overview2020In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1616, article id 460790Article in journal (Refereed)
    Abstract [en]

    Biological samples are usually complex matrices due to the presence of proteins, salts and a variety of organic compounds with chemical properties similar to those of the target analytes. Therefore, sample preparation is often mandatory in order to isolate the analytes from troublesome matrices before instrumental analysis. Because the number of samples in drug development, doping analysis, forensic science, toxicological analysis, and preclinical and clinical assays is steadily increasing, novel high throughput sample preparation approaches are calling for. The key factors in this development are the miniaturization and the automation of the sample preparation approaches so as to cope with most of the twelve principles of green chemistry. In this review, recent trends in sample preparation and novel strategies will be discussed in detail with particular focus on sorptive and liquid-phase microextraction in bioanalysis. The actual applicability of selective sorbents is also considered. Additionally, the role of 3D printing in microextraction for bioanalytical methods will be pinpointed.

  • 2.
    Abdollahi, Farnoosh
    et al.
    Department of Dentistry, Kashan University of Medical Science, Kashan, Iran.
    Saghatchi, Mahshid
    School of Metallurgy & Materials Engineering, Iran University of Science and Technology, Tehran, Iran.
    Paryab, Amirhosein
    Department of Materials Science & Engineering, Sharif University of Technology, Tehran, Iran.
    Malek Khachatourian, Adrine
    Department of Materials Science & Engineering, Sharif University of Technology, Tehran, Iran.
    Stephens, Emma D.
    Department of Biomedical Engineering, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada, 2500 University Drive NW.
    Toprak, Muhammet
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Badv, Maryam
    Department of Biomedical Engineering, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada, 2500 University Drive NW; Libin Cardiovascular Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada, 3330 Hospital Drive NW.
    Angiogenesis in bone tissue engineering via ceramic scaffolds: A review of concepts and recent advancements2024In: Biomaterials Advances, E-ISSN 2772-9508, Vol. 159, article id 213828Article, review/survey (Refereed)
    Abstract [en]

    Due to organ donor shortages, long transplant waitlists, and the complications/limitations associated with auto and allotransplantation, biomaterials and tissue-engineered models are gaining attention as feasible alternatives for replacing and reconstructing damaged organs and tissues. Among various tissue engineering applications, bone tissue engineering has become a promising strategy to replace or repair damaged bone. We aimed to provide an overview of bioactive ceramic scaffolds in bone tissue engineering, focusing on angiogenesis and the effect of different biofunctionalization strategies. Different routes to angiogenesis, including chemical induction through signaling molecules immobilized covalently or non-covalently, in situ secretion of angiogenic growth factors, and the degradation of inorganic scaffolds, are described. Physical induction mechanisms are also discussed, followed by a review of methods for fabricating bioactive ceramic scaffolds via microfabrication methods, such as photolithography and 3D printing. Finally, the strengths and weaknesses of the commonly used methodologies and future directions are discussed.

  • 3.
    Abduljabar, Haya Amer
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Sample Preparation Optimization for Laboratory Soft X-Ray Microscopy2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the introduction of nanoparticles in health care and daily products, the interaction between cells and nanoparticles is of great interest. There are many ways to examine these interactions, one of them being soft X-ray microscopy. It is a technique utilizing the water window to image biological samples, its greatest benefit being the non-invasive sample preparation, keeping the cell in a near-native state.

    The Stockholm Laboratory Soft X-ray Microscopy is a compact soft X-ray microscope that is currently being used to examine cell interactions. However, the sample preparations have been inconsistent and have yielded few useful and reproducible results. The purpose of this project is to optimize the cell preparation for better imaging using the Stockholm Laboratory Soft X-ray Microscope. 

    To reach the project goal to enable imaging of the nucleus and organelles in macrophages, this thesis will present a sample preparation protocol for macrophages where the concentration, blotting and cryo-fixation of the samples have been improved. The macrophage preparation was also tried on two other types of cells, amoeba and HEK 293 cells, to see if this preparation is universal for all cell lines. The results indicated that the most difficult and crucial step is the blotting, as too dry samples destroy the cells and too wet samples will yield almost no transmission in the microscope, making it impossible to image.

    Download full text (pdf)
    fulltext
  • 4.
    Aboode, Adam
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Utvärdering av prestanda hos ultraljudsmaskin2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The goal of this report is to try to evaluate the performance of an ultrasound scanner, which was bought by the applied physics department in 2014 for a relatively low price. By performing this evaluation we wish to answer the question if a scanner like this can be used to perform simple ultrasound examinations. Seeing that performance is such a broad concept we choose to limit ourselves in this report by focusing on the spatial resolution. The evaluation of spatial resolution was done experimentally by constructing multiple tissue-like phantoms and examining them. The results tell us that the scanner could probably be used on humans for simpler examinations such as estimation of the gestational age given that the scanner fulfils the safety requirements, something we do not investigate in this report.

  • 5. Abrahamsson, S.
    et al.
    Blom, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Agostinho, A.
    Jans, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Jost, A.
    Müller, M.
    Nilsson, Linnea
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Bernhem, K.
    Lambert, T. J.
    Heintzmann, R.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Multifocus structured illumination microscopy for fast volumetric super-resolution imaging2017In: Biomedical Optics Express, E-ISSN 2156-7085, Vol. 8, no 9, p. 4135-4140, article id #294866Article in journal (Refereed)
    Abstract [en]

    We here report for the first time the synergistic implementation of structured illumination microscopy (SIM) and multifocus microscopy (MFM). This imaging modality is designed to alleviate the problem of insufficient volumetric acquisition speed in superresolution biological imaging. SIM is a wide-field super-resolution technique that allows imaging with visible light beyond the classical diffraction limit. Employing multifocus diffractive optics we obtain simultaneous wide-field 3D imaging capability in the SIM acquisition sequence, improving volumetric acquisition speed by an order of magnitude. Imaging performance is demonstrated on biological specimens.

  • 6.
    Abrami, Laurence
    et al.
    Ecole Polytech Fed Lausanne, Global Hlth Inst, Sch Life Sci, Lausanne, Switzerland..
    Audagnotto, Martina
    Ecole Polytech Fed Lausanne, Inst Bioengn, Sch Life Sci, Lausanne, Switzerland..
    Ho, Sylvia
    Ecole Polytech Fed Lausanne, Global Hlth Inst, Sch Life Sci, Lausanne, Switzerland..
    Marcaida, Maria Jose
    Ecole Polytech Fed Lausanne, Inst Bioengn, Sch Life Sci, Lausanne, Switzerland..
    Mesquita, Francisco S.
    Ecole Polytech Fed Lausanne, Global Hlth Inst, Sch Life Sci, Lausanne, Switzerland..
    Anwar, Muhammad U.
    Ecole Polytech Fed Lausanne, Global Hlth Inst, Sch Life Sci, Lausanne, Switzerland..
    Sandoz, Patrick
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab. Ecole Polytech Fed Lausanne, Global Hlth Inst, Sch Life Sci, Lausanne, Switzerland..
    Fonti, Giulia
    Ecole Polytech Fed Lausanne, Inst Bioengn, Sch Life Sci, Lausanne, Switzerland..
    Pojer, Florence
    Ecole Polytech Fed Lausanne, Sch Life Sci, Prot Prod & Struct Core Facil, Lausanne, Switzerland..
    Dal Peraro, Matteo
    Ecole Polytech Fed Lausanne, Inst Bioengn, Sch Life Sci, Lausanne, Switzerland..
    van der Goot, F. Gisou
    Ecole Polytech Fed Lausanne, Global Hlth Inst, Sch Life Sci, Lausanne, Switzerland..
    Palmitoylated acyl protein thioesterase APT2 deforms membranes to extract substrate acyl chains2021In: Nature Chemical Biology, ISSN 1552-4450, E-ISSN 1552-4469, Vol. 17, no 4, p. 438-U173Article in journal (Refereed)
    Abstract [en]

    Acyl protein thioesterase APT2 interacts with membranes via its charged beta-tongue, becomes palmitoylated by ZDHHC3/7 and deforms the bilayer to extract substrate acyl chains. APT2 deacylation leads to its membrane release and degradation. Many biochemical reactions require controlled recruitment of proteins to membranes. This is largely regulated by posttranslational modifications. A frequent one is S-acylation, which consists of the addition of acyl chains and can be reversed by poorly understood acyl protein thioesterases (APTs). Using a panel of computational and experimental approaches, we dissect the mode of action of the major cellular thioesterase APT2 (LYPLA2). We show that soluble APT2 is vulnerable to proteasomal degradation, from which membrane binding protects it. Interaction with membranes requires three consecutive steps: electrostatic attraction, insertion of a hydrophobic loop and S-acylation by the palmitoyltransferases ZDHHC3 or ZDHHC7. Once bound, APT2 is predicted to deform the lipid bilayer to extract the acyl chain bound to its substrate and capture it in a hydrophobic pocket to allow hydrolysis. This molecular understanding of APT2 paves the way to understand the dynamics of APT2-mediated deacylation of substrates throughout the endomembrane system.

  • 7. Ackermann, M.
    et al.
    Albert, A.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Bissaldi, E.
    Bloom, E. D.
    Bonino, R.
    Brandt, T. J.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Caliandro, G. A.
    Cameron, R. A.
    Caragiulo, M.
    Caraveo, P. A.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Cohen-Tanugi, J.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Desiante, R.
    Digel, S. W.
    Drell, P. S.
    Favuzzi, C.
    Ferrara, E. C.
    Focke, W. B.
    Franckowiak, A.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giordano, F.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M. -H
    Guillemot, L.
    Guiriec, S.
    Harding, A. K.
    Hill, A. B.
    Horan, D.
    Johannesson, G.
    Knoedlseder, J.
    Kuss, M.
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Applied Physics. Oskar Klein Centre for Cosmoparticle Physics, Alba Nova, Sweden.
    Latronico, L.
    Li, J.
    Li, Liang
    KTH, School of Engineering Sciences (SCI), Applied Physics. Oskar Klein Centre for Cosmoparticle Physics, Alba Nova, Sweden.
    Longo, F.
    Loparco, F.
    Lubrano, P.
    Maldera, S.
    Martin, P.
    Mayer, M.
    Mazziotta, M. N.
    Michelson, P. F.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Murgia, S.
    Nuss, E.
    Ohsugi, T.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Romani, R. W.
    Sanchez-Conde, M.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Takahashi, H.
    Thayer, J. B.
    Tibaldo, L.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Vianello, G.
    Wood, M.
    Zimmer, S.
    Deep view of the Large Magellanic Cloud with six years of Fermi-LAT observations2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 586, article id A71Article in journal (Refereed)
    Abstract [en]

    Context. The nearby Large Magellanic Cloud (LMC) provides a rare opportunity of a spatially resolved view of an external star-forming galaxy in gamma-rays. The LMC was detected at 0.1-100 GeV as an extended source with CGRO/EGRET and using early observations with the Fermi-LAT. The emission was found to correlate with massive star-forming regions and to be particularly bright towards 30 Doradus. Aims. Studies of the origin and transport of cosmic rays (CRs) in the Milky Way are frequently hampered by line-of-sight confusion and poor distance determination. The LMC offers a complementary way to address these questions by revealing whether and how the gamma-ray emission is connected to specific objects, populations of objects, and structures in the galaxy. Methods. We revisited the gamma-ray emission from the LMC using about 73 months of Fermi-LAT P7REP data in the 0.2-100 GeV range. We developed a complete spatial and spectral model of the LMC emission, for which we tested several approaches: a simple geometrical description, template-fitting, and a physically driven model for CR-induced interstellar emission. Results. In addition to identifying PSR J0540-6919 through its pulsations, we find two hard sources positionally coincident with plerion N 157B and supernova remnant N 132D, which were also detected at TeV energies with H.E.S.S. We detect an additional soft source that is currently unidentified. Extended emission dominates the total flux from the LMC. It consists of an extended component of about the size of the galaxy and additional emission from three to four regions with degree-scale sizes. If it is interpreted as CRs interacting with interstellar gas, the large-scale emission implies a large-scale population of similar to 1-100 GeV CRs with a density of similar to 30% of the local Galactic value. On top of that, the three to four small-scale emission regions would correspond to enhancements of the CR density by factors 2 to 6 or higher, possibly more energetic and younger populations of CRs compared to the large-scale population. An alternative explanation is that this is emission from an unresolved population of at least two dozen objects, such as pulsars and their nebulae or supernova remnants. This small-scale extended emission has a spatial distribution that does not clearly correlate with known components of the LMC, except for a possible relation to cavities and supergiant shells. Conclusions. The Fermi-LAT GeV observations allowed us to detect individual sources in the LMC. Three of the newly discovered sources are associated with rare and extreme objects. The 30 Doradus region is prominent in GeV gamma-rays because PSR J0540-6919 and N 157B are strong emitters. The extended emission from the galaxy has an unexpected spatial distribution, and observations at higher energies and in radio may help to clarify its origin.

  • 8.
    Adshead, Mason
    et al.
    Photon Science Institute, Department of Electrical and Electronic Engineering, University of Manchester, Manchester, M13 9PL, UK.
    Sanaee, Maryam
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Blight, Daniel
    Photon Science Institute, Department of Electrical and Electronic Engineering, University of Manchester, Manchester, M13 9PL, UK.
    Prencipe, Alessandro
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Curry, Richard J.
    Photon Science Institute, Department of Electrical and Electronic Engineering, University of Manchester, Manchester, M13 9PL, UK.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Erbium implantation in thin film Lithium Niobate2023In: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023Conference paper (Refereed)
    Abstract [en]

    Lithium niobate on insulator (LNOI), thanks to its electro-optic properties and second order nonlinearity, is one of the most promising photonic materials for on-chip implementation of a complex photonic integrated circuit (PIC) [1]. Integration of rare earth ion emitters (RIE), characterized by high coherent transitions in both optical and microwave domains, into LNOI is a very attractive perspective to fully exploit the potential of this material in quantum optics applications and for on chip light generation and amplification. By choosing Erbium ions these functionalities can be implemented at telecom wavelengths (~1550 nm). Erbium integration in LNOI can be achieved using the smart cut technique [2]. However, this approach implies heating the material up to ~1100 ºC, approaching the Curie temperature of lithium niobate (~1200 ºC). Ion implantation also permits the incorporation of RIE into the lithium niobate (LN) crystal structure, operating at lower temperature with high spatial precision of the doped region in a complex PIC.

  • 9.
    Aghajafari, Elaheh
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Fabrication and characterization of GaAsxP1-x single junction solar cell on Si for III-V/Si tandem solar cell2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Silicon based solar cells have been used as photovoltaic devices for decades due to reasonable cost and environment- friendly nature of silicon. But the conversion efficiency of silicon solar cell is limited; for instance, the maximum conversion efficiency of a crystalline silicon solar cell available in the market developed by Kaneka Corporation is 26 % [1]. In comparison, III-V compound semiconductor multi-junction solar cells are the most efficient solar cells with efficiency of 47.1% [2]. However, due to high-cost substrate materials, III-V solar cells are not the best option for large scale production in real life. Therefore, integration of III-V compound semiconductors on silicon substrate has been studied to obtain III-V/Si multi junction solar cells with high conversion efficiency with reasonable price. To this end, we studied epitaxial growth of on GaAs deposited on Si.This thesis presents the characterization results of the above epitaxial layer and fabrication of a single junction solar cell on GaAs coated Si substrate and its performance.In the first part of the project, epitaxial layer grown by Hydride Vapor Phase Epitaxy (HVPE) on different kinds of substrates at different growth conditions are characterized to identify the optimized growth conditions and a suitable substrate. Samples are characterized by High Resolution X-ray Diffraction (HRXRD) and photoluminescence (PL) to determine the composition of and its crystalline quality and by optical microscope to assess the surface morphology. Scanning Electron Microscope (SEM) is used to study the depth of the dry etched structures.The second part of the project deals with the fabrication process consisting of 21 steps to obtain a single junction solar cell structure on GaAs/Si. This process flow will be explained in some detail along with a brief description of several tools in cleanroom that have been used for this purpose.Finally, in the third part, devices are characterized to investigate their performance. Transmission Line Method (TLM) is used to obtain important parameters such as specific contact resistance. Current- voltage (I-V) relation of solar cell is investigated to acquire its efficiency. The lowest specific contact resistance measured in this project is for p-contact (for 4041DV- cell 8) and the highest efficiency measured is 1.64% (for 4041DV- cell 6).In conclusion, although the results obtained are far from the state-of-the art results, this work has laid the foundation for future work that can lead to a breakthrough in fabricating multi-junction tandem solar cell on silicon.

    Download full text (pdf)
    fulltext
  • 10. Agostinho, A.
    et al.
    Kouznetsova, A.
    Hernández-Hernández, A.
    Bernhem, Kristoffer
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Blom, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Höög, C.
    Sexual dimorphism in the width of the mouse synaptonemal complex2018In: Journal of Cell Science, ISSN 0021-9533, E-ISSN 1477-9137, Vol. 131, no 5, article id jcs212548Article in journal (Refereed)
    Abstract [en]

    Sexual dimorphism has been used to describe morphological differences between the sexes, but can be extended to any biologically related process that varies between males and females. The synaptonemal complex (SC) is a tripartite structure that connects homologous chromosomes in meiosis. Here, aided by superresolution microscopy techniques, we show that the SC is subject to sexual dimorphism, in mouse germ cells. We have identified a significantly narrower SC in oocytes and have established that this difference does not arise from a different organization of the lateral elements nor from a different isoform of transverse filament protein SYCP1. Instead, we provide evidence for the existence of a narrower central element and a different integration site for the C-termini of SYCP1, in females. In addition to these female-specific features, we speculate that post-translation modifications affecting the SYCP1 coiled-coil region could render a more compact conformation, thus contributing to the narrower SC observed in females.

  • 11. Agostinho, Ana
    et al.
    Manneberg, Otto
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    van Schendel, Robin
    Hernandez-Hernandez, Abrahan
    Kouznetsova, Anna
    Blom, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Höög, Christer
    High density of REC8 constrains sister chromatid axes and prevents illegitimate synaptonemal complex formation2016In: EMBO Reports, ISSN 1469-221X, E-ISSN 1469-3178, Vol. 17, no 6, p. 901-913Article in journal (Refereed)
    Abstract [en]

    During meiosis, cohesin complexes mediate sister chromatid cohesion (SCC), synaptonemal complex (SC) assembly and synapsis. Here, using super-resolution microscopy, we imaged sister chromatid axes in mouse meiocytes that have normal or reduced levels of cohesin complexes, assessing the relationship between localization of cohesin complexes, SCC and SC formation. We show that REC8 foci are separated from each other by a distance smaller than 15% of the total chromosome axis length in wild-type meiocytes. Reduced levels of cohesin complexes result in a local separation of sister chromatid axial elements (LSAEs), as well as illegitimate SC formation at these sites. REC8 but not RAD21 or RAD21L cohesin complexes flank sites of LSAEs, whereas RAD21 and RAD21L appear predominantly along the separated sister-chromatid axes. Based on these observations and a quantitative distribution analysis of REC8 along sister chromatid axes, we propose that the high density of randomly distributed REC8 cohesin complexes promotes SCC and prevents illegitimate SC formation.

  • 12.
    Ahlberg, Martina
    et al.
    Univ Gothenburg, Dept Phys, S-41296 Gothenburg, Sweden..
    Chung, Sunjae
    Univ Gothenburg, Dept Phys, S-41296 Gothenburg, Sweden.;Korea Natl Univ Educ, Dept Phys Educ, Cheongju 28173, South Korea..
    Jiang, Sheng
    KTH, School of Engineering Sciences (SCI), Applied Physics. Univ Gothenburg, Dept Phys.
    Frisk, Andreas
    Univ Gothenburg, Dept Phys, S-41296 Gothenburg, Sweden..
    Khademi, Maha
    Shahid Beheshti Univ, Dept Phys, Tehran 1983969411, Iran..
    Khymyn, Roman
    Univ Gothenburg, Dept Phys, S-41296 Gothenburg, Sweden..
    Awad, Ahmad A.
    Univ Gothenburg, Dept Phys, S-41296 Gothenburg, Sweden..
    Le, Quang Tuan
    KTH, School of Engineering Sciences (SCI), Applied Physics. Univ Gothenburg, Dept Phys.
    Mazraati, Hamid
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics. NanOsc AB, S-16440 Kista, Sweden..
    Mohseni, Majid
    KTH, School of Engineering Sciences (SCI), Applied Physics. Shahid Beheshti Univ, Dept Phys, Tehran 1983969411, Iran..
    Weigand, Markus
    Max Planck Inst Intelligent Syst, Stuttgart, Germany..
    Bykova, Iuliia
    Max Planck Inst Intelligent Syst, Stuttgart, Germany..
    Gross, Felix
    Max Planck Inst Intelligent Syst, Stuttgart, Germany..
    Goering, Eberhard
    Max Planck Inst Intelligent Syst, Stuttgart, Germany..
    Schutz, Gisela
    Max Planck Inst Intelligent Syst, Stuttgart, Germany..
    Grafe, Joachim
    Max Planck Inst Intelligent Syst, Stuttgart, Germany..
    Åkerman, Johan
    KTH, School of Engineering Sciences (SCI), Applied Physics. Univ Gothenburg, Dept Phys.
    Freezing and thawing magnetic droplet solitons2022In: Nature Communications, E-ISSN 2041-1723, Vol. 13, no 1, article id 2462Article in journal (Refereed)
    Abstract [en]

    Magnetic droplets are a type of non-topological magnetic soliton, which are stabilised and sustained by spin-transfer torques for instance. Without this, they would collapse. Here Ahlberg et al show that by decreasing the applied magnetic field, droplets can be frozen, forming a static nanobubble Magnetic droplets are non-topological magnetodynamical solitons displaying a wide range of complex dynamic phenomena with potential for microwave signal generation. Bubbles, on the other hand, are internally static cylindrical magnetic domains, stabilized by external fields and magnetostatic interactions. In its original theory, the droplet was described as an imminently collapsing bubble stabilized by spin transfer torque and, in its zero-frequency limit, as equivalent to a bubble. Without nanoscale lateral confinement, pinning, or an external applied field, such a nanobubble is unstable, and should collapse. Here, we show that we can freeze dynamic droplets into static nanobubbles by decreasing the magnetic field. While the bubble has virtually the same resistance as the droplet, all signs of low-frequency microwave noise disappear. The transition is fully reversible and the bubble can be thawed back into a droplet if the magnetic field is increased under current. Whereas the droplet collapses without a sustaining current, the bubble is highly stable and remains intact for days without external drive. Electrical measurements are complemented by direct observation using scanning transmission x-ray microscopy, which corroborates the analysis and confirms that the bubble is stabilized by pinning.

  • 13.
    Ahmadi, Khadijeh
    et al.
    Shahid Beheshti Univ, Dept Phys, Tehran 19839, Iran.;Univ Tehran, Coll Engn, Adv Magnet Mat Res Ctr, Sch Met & Mat, Tehran 111554563, Iran..
    Mahfouzi, Farzad
    Calif State Univ Northridge, Dept Phys & Astron, Northridge, CA 91330 USA..
    Jamilpanah, Loghman
    Shahid Beheshti Univ, Dept Phys, Tehran 19839, Iran..
    Mohseni, Morteza
    Tech Univ Kaiserslautern, Fachbereich Phys & Landesforschungszentrum OPTIMA, D-67663 Kaiserslautern, Germany..
    Boettcher, Tobias
    Tech Univ Kaiserslautern, Fachbereich Phys & Landesforschungszentrum OPTIMA, D-67663 Kaiserslautern, Germany..
    Pirro, Philipp
    Tech Univ Kaiserslautern, Fachbereich Phys & Landesforschungszentrum OPTIMA, D-67663 Kaiserslautern, Germany..
    Kioussis, Nicholas
    Calif State Univ Northridge, Dept Phys & Astron, Northridge, CA 91330 USA..
    Åkerman, Johan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics. ;Univ Gothenburg, Dept Phys, S-41296 Gothenburg, Sweden..
    Ebrahimi, S. A. Seyyed
    Univ Tehran, Coll Engn, Adv Magnet Mat Res Ctr, Sch Met & Mat, Tehran 111554563, Iran..
    Mohseni, Seyed Majid
    Shahid Beheshti Univ, Dept Phys, Tehran 19839, Iran..
    Inducing Dzyaloshinskii-Moriya interaction in symmetrical multilayers using post annealing2022In: Scientific Reports, E-ISSN 2045-2322, Vol. 12, no 1, article id 11877Article in journal (Refereed)
    Abstract [en]

    The interfacial Dzyaloshinskii-Moriya Interaction (iDMI) is an antisymmetric exchange interaction that is induced by the broken inversion symmetry at the interface of, e.g., a ferromagnet/heavy metal. Thus, the presence of iDMI is not expected in symmetrical multilayer stacks of such structures. Here, we use thermal annealing to induce the iDMI in a [Py/Pt](x10) symmetrical multilayer stack. Brillouin light scattering spectroscopy is used to directly evidence the iDMI induction in the annealed sample. Structural characterizations highlight the modified crystallinity as well as a higher surface roughness of the sample after annealing. First principles electronic structure calculations demonstrate a monotonic increase of the iDMI with the interfacial disorder due to the interdiffusion of atoms, depicting the possible origin of the induced iDMI. The presented method can be used to tune the iDMI strength in symmetric multilayers, which are the integral part of racetrack memories, magnonic devices as well as spin-orbitronic elements.

  • 14.
    Ahmadi, Mazaher
    et al.
    Bu Ali Sina Univ, Fac Chem, Hamadan, Iran..
    Moein, Mohammad Mahdi
    Karolinska Inst, Ctr Psychiat Res, Dept Clin Neurosci, SE-17176 Stockholm, Sweden.;Stockholm Cty Council, SE-17176 Stockholm, Sweden..
    Madrakian, Tayyebeh
    Bu Ali Sina Univ, Fac Chem, Hamadan, Iran..
    Afkhami, Abbas
    Bu Ali Sina Univ, Fac Chem, Hamadan, Iran..
    Bahar, Soleiman
    Univ Kurdistan, Fac Sci, Dept Chem, Sanandaj, Iran..
    Abdel-Rehim, Mohamed
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics. Karolinska Inst, Ctr Psychiat Res, Dept Clin Neurosci, SE-17176 Stockholm, Sweden.;Stockholm Cty Council, SE-17176 Stockholm, Sweden..
    Reduced graphene oxide as an efficient sorbent in microextraction by packed sorbent: Determination of local anesthetics in human plasma and saliva samples utilizing liquid chromatography-tandem mass spectrometry2018In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1095, p. 177-182Article in journal (Refereed)
    Abstract [en]

    Herein, reduced graphene oxide (RGO) has been utilized as an efficient sorbent in microextraction by packed sorbent (MEPS). The combination of MEPS and liquid chromatography-tandem mass spectrometry has been used to develop a method for the extraction and determination of three local anesthetics (i.e. lidocaine, prilocaine, and ropivacaine) in human plasma and saliva samples. The results showed that the utilization of RGO in MEPS could minimize the matrix effect so that no interfering peaks at the retention times of the analytes or internal standard was observed. The high extraction efficiency of this method was approved by mean recoveries of 97.26-106.83% and 95.21-105.83% for the studied analytes in plasma and saliva samples, respectively. Intra- and inter-day accuracies and precisions for all analytes were in good accordance with the international regulations. The accuracy values (as percentage deviation from the nominal value) of the quality control samples were between - 2.1 to 13.9 for lidocaine, - 4.2 to 11.0 for prilocaine and between - 4.5 to - 2.4 for ropivacaine in plasma samples while the values were ranged from - 4.6 to 1.6 for lidocaine, from - 4.2 to 15.5 for prilocaine and from - 3.3 to - 2.3 for ropivacaine in human saliva samples. Lower and upper limit of quantification (LLOQ, ULOQ) were set at 5 and 2000 nmol L-1 for all of the studied drugs. The correlation coefficients values were >= 0.995. The limit of detection values were obtained 4 nmol L-1 for lidocaine and prilocaine, and 2 nmol L-1 for ropivacaine.

  • 15.
    Aho, Noora
    et al.
    Nanoscience Center and Department of Chemistry, University of Jyväskylä, 40014Jyväskylä, Finland.
    Buslaev, Pavel
    Nanoscience Center and Department of Chemistry, University of Jyväskylä, 40014Jyväskylä, Finland.
    Jansen, Anton
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Bauer, Paul
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Groenhof, Gerrit
    Nanoscience Center and Department of Chemistry, University of Jyväskylä, 40014Jyväskylä, Finland.
    Hess, Berk
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Scalable Constant pH Molecular Dynamics in GROMACS2022In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 18, no 10, p. 6148-6160Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics (MD) computer simulations are used routinely to compute atomistic trajectories of complex systems. Systems are simulated in various ensembles, depending on the experimental conditions one aims to mimic. While constant energy, temperature, volume, and pressure are rather straightforward to model, pH, which is an equally important parameter in experiments, is more difficult to account for in simulations. Although a constant pH algorithm based on the λ-dynamics approach by Brooks and co-workers [Kong, X.; Brooks III, C. L. J. Chem. Phys.1996, 105, 2414–2423] was implemented in a fork of the GROMACS molecular dynamics program, uptake has been rather limited, presumably due to the poor scaling of that code with respect to the number of titratable sites. To overcome this limitation, we implemented an alternative scheme for interpolating the Hamiltonians of the protonation states that makes the constant pH molecular dynamics simulations almost as fast as a normal MD simulation with GROMACS. In addition, we implemented a simpler scheme, called multisite representation, for modeling side chains with multiple titratable sites, such as imidazole rings. This scheme, which is based on constraining the sum of the λ-coordinates, not only reduces the complexity associated with parametrizing the intramolecular interactions between the sites but also is easily extendable to other molecules with multiple titratable sites. With the combination of a more efficient interpolation scheme and multisite representation of titratable groups, we anticipate a rapid uptake of constant pH molecular dynamics simulations within the GROMACS user community.

  • 16.
    Ait Abdelkader, Nazim
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Design of III-V hybrid membrane laser2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 17.
    Ajello, M.
    et al.
    Clemson Univ, Dept Phys & Astron, Kinard Lab Phys, Clemson, SC 29634 USA..
    Jóhannesson, Gudlaugur
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Univ Iceland, Sci Inst, IS-107 Reykjavik, Iceland.;NORDITA, Royal Inst Technol, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden.;Stockholm Univ, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden..
    Kerr, M.
    Naval Res Lab, Space Sci Div, Washington, DC 20375 USA..
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Applied Physics. Oskar Klein Ctr Cosmoparticle Phys, AlbaNova, SE-10691 Stockholm, Sweden.;Dalarna Univ, Sch Educ Hlth & Social Studies, Nat Sci, SE-79188 Falun, Sweden..
    Parthasarathy, A.
    Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany..
    Zaharijas, G.
    Univ Nova Gorica, Ctr Astrophys & Cosmol, Nova Gorica, Slovenia..
    A gamma-ray pulsar timing array constrains the nanohertz gravitational wave background2022In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 376, no 6592, p. 521-523Article in journal (Refereed)
    Abstract [en]

    After large galaxies merge, their central supermassive black holes are expected to form binary systems. Their orbital motion should generate a gravitational wave background (GWB) at nanohertz frequencies. Searches for this background use pulsar timing arrays, which perform long-term monitoring of millisecond pulsars at radio wavelengths. We used 12.5 years of Fermi Large Area Telescope data to form a gamma-ray pulsar timing array. Results from 35 bright gamma-ray pulsars place a 95% credible limit on the GWB characteristic strain of 1.0 x 10(-14) at a frequency of 1 year(-1). The sensitivity is expected to scale with t(obs), the observing time span, as t(obs)(-13/6). This direct measurement provides an independent probe of the GWB while offering a check on radio noise models.

  • 18.
    Akan, Rabia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Metal-assisted chemical etching for nanofabrication of hard X-ray zone plates2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Hard X-ray scanning microscopes, or nanoprobes, make it possible to image samples and probe their chemical, elemental and structural properties at nanoscale resolution. This is enabled by the use of nanofocusing optics. Commonly used optics in nanoprobes for high resolution X-ray experiments are zone plates. Zone plates are circular diffraction optics with radially decreasing grating periods. Their performance depends on their geometrical properties and material. The width of the outermost zone, which today is in the order of a few tens of nanometers, defines the zone plate resolution, while the zone thickness and the material define the X-ray focusing efficiency. For hard X-ray zone plates, the required zone thickness is several micrometers. Therefore, high-aspect ratio nanostructures are a prerequisite for high-resolution, high-efficiency zone plates. The very small structures together with the high-aspect ratios make zone plates one of the most challenging devices to fabricate. A wet-chemical nanofabrication process that has proved its capability of providing silicon nanostructures with ultra-high aspect ratios is metal-assisted chemical etching (MACE). MACE is an electroless, autocatalytic pattern transfer method that uses an etching solution to selectively etch a predefined noble metal pattern into silicon. In this thesis, MACE is optimized specifically for zone plate nanostructures and used in the development of a new zone plate device nanofabrication process. The MACE optimization for silicon zone plate nanostructures involved a systematic investigation of a wide parameter space. The preferable etching solution composition, process temperature, zone plate catalyst design and silicon type were identified. Parameter dependencies were characterized with respect to etching depth and verticality, mechanical stability of zones and silicon surface roughness. Zone plate molds with aspect ratios of 30:1 at 30 nm zone widths were nanofabricated using the optimized MACE process. For use with hard X-rays, the silicon molds were metallized with palladium using electroless deposition (ELD). The first order diffraction efficiency of such a palladium/silicon zone plate was characterized as 1.9 %. Both MACE for the zone plate pattern transfer and ELD for the silicon mold metalization are conceptually simple, relatively low-cost and accessible methods, which opens up for further developments of zone plate device nanofabrication processes.

    Download full text (pdf)
    fulltext
  • 19.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Frisk, Thomas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundberg, Fabian
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Ohlin, Hanna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Johansson, Ulf
    Lund Univ, MAX IV Lab, S-22100 Lund, Sweden..
    Li, Kenan
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA..
    Sakdinawat, Anne
    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA..
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Metal-Assisted Chemical Etching and Electroless Deposition for Fabrication of Hard X-ray Pd/Si Zone Plates2020In: Micromachines, E-ISSN 2072-666X, Vol. 11, no 3, article id 301Article in journal (Refereed)
    Abstract [en]

    Zone plates are diffractive optics commonly used in X-ray microscopes. Here, we present a wet-chemical approach for fabricating high aspect ratio Pd/Si zone plate optics aimed at the hard X-ray regime. A Si zone plate mold is fabricated via metal-assisted chemical etching (MACE) and further metalized with Pd via electroless deposition (ELD). MACE results in vertical Si zones with high aspect ratios. The observed MACE rate with our zone plate design is 700 nm/min. The ELD metallization yields a Pd density of 10.7 g/cm3, a value slightly lower than the theoretical density of 12 g/cm3. Fabricated zone plates have a grid design, 1:1 line-to-space-ratio, 30 nm outermost zone width, and an aspect ratio of 30:1. At 9 keV X-ray energy, the zone plate device shows a first order diffraction efficiency of 1.9%, measured at the MAX IV NanoMAX beamline. With this work, the possibility is opened to fabricate X-ray zone plates with low-cost etching and metallization methods.

  • 20.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Parfeniukas, Karolis
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Toprak, M. S.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructures2018In: RSC Advances, E-ISSN 2046-2069, Vol. 8, no 23, p. 12628-12634Article in journal (Refereed)
    Abstract [en]

    Metal-assisted chemical etching (MACE) reaction parameters were investigated for the fabrication of specially designed silicon-based X-ray zone plate nanostructures using a gold catalyst pattern and etching solutions composed of HF and H2O2. Etching depth, zone verticality and zone roughness were studied as a function of etching solution composition, temperature and processing time. Homogeneous, vertical etching with increasing depth is observed at increasing H2O2 concentrations and elevated processing temperatures, implying a balance in the hole injection and silica dissolution kinetics at the gold-silicon interface. The etching depth decreases and zone roughness increases at the highest investigated H2O2 concentration and temperature. Possible reasons for these observations are discussed based on reaction chemistry and zone plate design. Optimum MACE conditions are found at HFH2O2 concentrations of 4.7 M:0.68 M and room temperature with an etching rate of ≈0.7 μm min-1, which is about an order of magnitude higher than previous reports. Moreover, our results show that a grid catalyst design is important for successful fabrication of vertical high aspect ratio silicon nanostructures. 

  • 21.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Parfeniukas, Karolis
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Toprak, Muhammet S.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructuresManuscript (preprint) (Other academic)
    Abstract [en]

    Metal-assisted chemical etching (MACE) reaction parameters were investigated for the fabrication of specially designed silicon-based x-ray zone plate nanostructures using a gold catalyst pattern and etching solutions composed of HF and H2O2. Etching depth, zone verticality and zone roughness were studied as a function of etching solution composition, temperature and processing time. Homogeneous, vertical etching with increasing depth is observed at increasing H2O2 concentrations and elevated processing temperatures, implying a balance in the hole injection and silica dissolution kinetics at the gold-silicon interface. The etching depth decreases and zone roughness increases at the highest investigated H2O2 concentration and temperature. Possible reasons for these observations are discussed based on reaction chemistry and zone plate design. Optimum MACE conditions are found at HF:H2O2 concentrations of 4.7 M:0.68 M and room temperature with an etching rate of 0.7 micrometers per minute, which is about an order of magnitude higher than previous reports. Moreover, our results show that a grid catalyst design is important for successful fabrication of vertical high aspect ratio silicon nanostructures.

  • 22.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Parfeniukas, Karolis
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Toprak, Muhammet
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Investigation of Metal-Assisted Chemical Etching for Fabrication of Silicon-Based X-Ray Zone Plates2018In: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115Article in journal (Refereed)
    Download full text (pdf)
    fulltext
  • 23.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Optimization of metal-assisted chemical etching for deep silicon nanostructuresManuscript (preprint) (Other academic)
  • 24.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Optimization of Metal-Assisted Chemical Etching for Deep Silicon Nanostructures2021In: Nanomaterials, E-ISSN 2079-4991, Vol. 11, no 11, article id 2806Article in journal (Refereed)
    Abstract [en]

    High-aspect ratio silicon (Si) nanostructures are important for many applications. Metal-assisted chemical etching (MACE) is a wet-chemical method used for the fabrication of nanostructured Si. Two main challenges exist with etching Si structures in the nanometer range with MACE: keeping mechanical stability at high aspect ratios and maintaining a vertical etching profile. In this work, we investigated the etching behavior of two zone plate catalyst designs in a systematic manner at four different MACE conditions as a function of mechanical stability and etching verticality. The zone plate catalyst designs served as models for Si nanostructures over a wide range of feature sizes ranging from 850 nm to 30 nm at 1:1 line-to-space ratio. The first design was a grid-like, interconnected catalyst (brick wall) and the second design was a hybrid catalyst that was partly isolated, partly interconnected (fishbone). Results showed that the brick wall design was mechanically stable up to an aspect ratio of 30:1 with vertical Si structures at most investigated conditions. The fishbone design showed higher mechanical stability thanks to the Si backbone in the design, but on the other hand required careful control of the reaction kinetics for etching verticality. The influence of MACE reaction kinetics was identified by lowering the oxidant concentration, lowering the processing temperature and by isopropanol addition. We report an optimized MACE condition to achieve an aspect ratio of at least 100:1 at room temperature processing by incorporating isopropanol in the etching solution.

  • 25.
    Akhtar, Moeen
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Characterization of industrial foulants and designing antifouling surfaces2021Independent thesis Advanced level (degree of Master of Fine Arts (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Industries (food, beverage, petrochemical, etc.) normally use various gravitational separation echniques in their processes. Such separation processes often suffer from the deposition of undesirable material on the active surfaces of the process equipment, e.g. a high-speed separator or decanter, causing a slew of problems with the process or product quality. To restore operational efficiencies, additional cleaning steps using both water and chemicals are required, making the process more expensive and less environmentally friendly. Other than operating time and concentration of the process fluid there are several factors such as surface nature, surface roughness, type of material, surface charge, etc which influence the fouling deposition of surfaces. Fouling on the surfaces can grow following different mechanisms. The goal of this research work is to learn more about the nature of foulant interactions with stainless steel surfaces and eventually design some antifouling methodology. It is too difficult to study foulingfor all kinds of solutions and industries, so we tried to investigate the organic deposition in dairy and brewery industries by using lab-scale synthesized milk and beer solutions, For quantitative and statistical examination of these characteristics, several experimental approaches (FTIR, percent weight change, surface roughness, surface energy) were used. It was confirmed that fouling grows on the surfaces in a non-linear fashion irrespective of the time and concentration of the solution. The fouling of surfaces can be improved by producing more hydrophilic surfaces or by reducing surface roughness. Steric hindrance, electrostatic charge, and water barrier or hydration layer theories can be used to modify the surface nature and hence the fouling deposition. For antifouling purposes, PMMA (organic) and tungsten oxide (inorganic) coatings were employed. The PMMA was deposited using a dip-coating technique using (6%,10%, and 12%) PMMA solution, and the tungsten oxide coating was carried out by using a standard two electrode electrochemical system under different voltage (3.5V and 4.5V) and time (5min, 10 min, and 20 min) conditions. The coatings were characterized by using different techniques and their antifouling effects were studied in model milk and model beer solutions

    Download full text (pdf)
    fulltext
  • 26.
    Akkuratov, Evgeny E.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    The Biophysics of Na+,K+-ATPase in neuronal health and disease2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Na+,K+-ATPase is one of the most important proteins in the mammalian cell. It creates sodium and potassium gradients which are fundamental for the membrane potential and sodium-dependent secondary active transport. It has a second role in the cell as a receptor that by binding chemicals from the cardiotonic steroids family, the most knowledgeable of them is ouabain, triggers various signaling pathways in the cell which regulate gene activation, proliferation, apoptosis, etc. It has been shown that several severe neurological diseases are associated with mutations in the Na+,K+-ATPase encoding genes. Although Na+,K+-ATPase was discovered already in 1957 by the Danish scientist Jens Skou, the knowledge about the function of this enzyme  is still not complete.

     

    In the studies included in the thesis, we have learned more about the function of Na+,K+-ATPase in different aspects of health and disease. In study I we showed a mechanism of ouabain-dependent regulation of the NMDA receptor, one of the most important receptors in the nervous system, via binding with Na+,K+-ATPase. This allows us to look at the Na+,K+-ATPase as regulator via protein-protein interaction. In study II we investigated a different aspect of Na+,K+-ATPase functioning – to look at how binding of ouabain to Na+,K+-ATPase activates a number of signaling cascades by looking at the phosphoproteome status of the cells. This allows us to see the whole picture of ouabain-mediated cascades and further characterize them. In study III we focused on the role of Na+,K+-ATPase in severe epileptic encephalopathy caused by a mutation in the ATP1A1 gene. We performed a molecular and cellular study to describe how mutations affects protein structure and function and found that this mutation converts the ion pump to a nonspecific leak channel. In study IV we performed a translational study of the most common mutation for rapid-onset dystonia-parkinsonism. We studied how this mutation affects the nervous system on the protein-, cellular-, and organism level and found that the complete absence of ultraslow afterhyperpolarization (usAHP) could explain gait disturbances found in patients. In the on-going study we showed that Na+,K+-ATPase can oligomerize and that this effect is triggered by ouabain binding to the Na+,K+-ATPase. In this study, we utilized a novel fluorescence labelling approach and used biophysical techniques with single molecule sensitivity to track Na+,K+-ATPase interactions.

     

    In summary, we applied biophysical and molecular methods to study different aspects of the function of Na+,K+-ATPase, and gained insights that could be helpful not only for answering fundamental questions about Na+,K+-ATPase but also to find a treatment for patients with diseases associated with mutations in this protein.

    Download full text (pdf)
    fulltext
    Download full text (pdf)
    media agreement
  • 27.
    Akkuratov, Evgeny E.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics.
    Sorrell, Frankie
    Souza, Vasco
    Paukar, Martin
    Picton, Laurence
    Jans, Daniel
    Andersson, Magnus
    Fritz, Nicolas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics.
    Zhang, Xiaoqun
    Liebmann, Thomas
    KTH.
    Lindskog, Maria
    KTH.
    Svenningsson, Per
    Miles, Gareth
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics.
    Aperia, Anita
    KTH.
    Mechanisms by which the T613M mutation causes mobility and gait disturbances in Rapid-Onset Dystonia-ParkinsonismManuscript (preprint) (Other academic)
  • 28.
    Akkuratov, Evgeny E.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Westin, Linda
    Vazquez-Juarez, Erika
    de Marothy, Minttu
    Melnikova, Aleksandra K
    Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia, 119234.
    Blom, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Lindskog, Maria
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Aperia, Anita
    Ouabain Modulates the Functional Interaction Between Na,K-ATPase and NMDA Receptor.2020In: Molecular Neurobiology, ISSN 0893-7648, E-ISSN 1559-1182, Vol. 57, no 10, p. 4018-4030Article in journal (Refereed)
    Abstract [en]

    The N-methyl-D-aspartate (NMDA) receptor plays an essential role in glutamatergic transmission and synaptic plasticity and researchers are seeking for different modulators of NMDA receptor function. One possible mechanism for its regulation could be through adjacent membrane proteins. NMDA receptors coprecipitate with Na,K-ATPase, indicating a potential interaction of these two proteins. Ouabain, a mammalian cardiotonic steroid that specifically binds to Na,K-ATPase and affects its conformation, can protect from some toxic effects of NMDA receptor activation. Here we have examined whether NMDA receptor activity and downstream effects can be modulated by physiological ouabain concentrations. The spatial colocalization between NMDA receptors and the Na,K-ATPase catalytic subunits on dendrites of cultured rat hippocampal neurons was analyzed with super-resolution dSTORM microscopy. The functional interaction was analyzed with calcium imaging of single hippocampal neurons exposed to 10 μM NMDA in presence and absence of ouabain and by determination of the ouabain effect on NMDA receptor-dependent long-term potentiation. We show that NMDA receptors and the Na,K-ATPase catalytic subunits alpha1 and alpha3 exist in same protein complex and that ouabain in nanomolar concentration consistently reduces the calcium response to NMDA. Downregulation of the NMDA response is not associated with internalization of the receptor or with alterations in its state of Src phosphorylation. Ouabain in nanomolar concentration elicits a long-term potentiation response. Our findings suggest that ouabain binding to a fraction of Na,K-ATPase molecules that cluster with the NMDA receptors will, via a conformational effect on the NMDA receptors, cause moderate but consistent reduction of NMDA receptor response at synaptic activation.

    Download full text (pdf)
    fulltext
  • 29.
    Akpe, Victor
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Photophysical and Chemical Approaches to Cellular Biophysics2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The central theme in this thesis is reversibility. Two main attempts has been made to approach reversibility in cellular systems from both chemical and physical points of view. Reversibility of immunolabeling of proteins on the cell surface has been adressed by development of new fluorescent substances optimized for CALI (Chromophore-Assisted Laser Inactivation of protein). Aluminum phthalocyanine (AlPc) is here identified to be a good candidate for a new generation of fluorophores for efficient hydroxyl radical generation. It is shown that cells can be reversibly labeled with antibody-AlPc conjugates. In experiments on living cells the AlPcs were not only active as classic fluorophores but also as photocatalytic substances with destaining properties. Reversibility of cell immobilization is also reported, where cells cultured in microstructures were immobilized and 3D supported using hydrogels. Hydrogel formulation and application was optimized to achieve a system where both viability and ease of use was satisfied. Gel reversibility was actualized with pH and enzyme treatment. The developped method offers the possibility of stop flow culturing cells in controlled and reusable 3D environments.

    Download full text (pdf)
    FULLTEXT01
  • 30.
    Akpe, Victor
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Nyokong, Tebello
    Osadebe, P. O.
    Photophysical and photochemical parameters of octakis (benzylthio) phthalocyaninato zinc, aluminium and tin: Red shift index concept in solvent effect on the ground state absorption of zinc phthalocyanine derivatives2010In: Journal of Molecular Structure, ISSN 0022-2860, E-ISSN 1872-8014, Vol. 984, no 1-3, p. 1-14Article in journal (Refereed)
    Abstract [en]

    This paper addresses the synthesis of octa-substituted benzylthio metallophthalocyanines (OBTMPcs) that contain the central metal ions of Zn2+, Al3+ and Sn4+. The ground state absorption of ZnPc(SR)(8) (OBTZnPc) along with the ZnPc derivatives, well documented in literature were used to study a new concept called the red shift index (RsI). The concept is based on the empirical values of RsI of the different complexes in solvent media. Unequivocally, parameters used in this paper show strong correlations that are consistent with the results obtained. For instance, 12,1 of the complexes tend to increase as the refractive index, n(D), and solvent donor, DN, of solvent increases. Photodegradation (photobleaching) quantum yield, phi(d) measurements of these compounds show that they are highly photostable, phi(d) (0.03-0.33 x 10(-5)). The triplet quantum yield, phi(T) (0.40-0.53) and the triplet lifetime, tau(T) (610-810 mu s) are within the typical range for metallophthalocyanines in DMSO. The photosensitisation efficiency. S-Delta, is relatively high for all the molecules (0.74-0.90). (C) 2010 Elsevier B.V. All rights reserved.

  • 31.
    Akpe, Victor
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Nyokong, Tebello
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Photophysics and photochemistry of zinc, aluminium and tin octakis (benzylthio) phthalocyanines2008Report (Other academic)
  • 32.
    Akpe, Victor
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Ogunsipe, Abimbola
    Madu, Christian
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Red-Shift Index Concept in Solvent Effects of Chromophore-Substituted Metallophthalocyanines: A Look at the Empirical Relationship of the Macroscopic Properties of the Solute-Solvent Interactions2015In: Journal of Solution Chemistry, ISSN 0095-9782, E-ISSN 1572-8927, Vol. 44, no 2, p. 307-326Article in journal (Refereed)
    Abstract [en]

    Solvent effects on the UV/vis spectra of metallopthalocyanines (MPcs) have been interpreted using the red-shift index concept (R (s) I). The concept connects empirically, direct, experimental, easily accessible optical spectral data, which are explained by considering the differential behavior of the solute-solvent interactions at the ground state and excited state using the spectral values of MPcs along with the derived concept, called the associated solvation energy (ASE). R (s) I is formulated from three fundamental parameters, which are: ground state electronic absorption spectrum, polarization red-shift and a scaling factor of MPc (N (dye)) in the respective solvents. The R (s) I is a reflection of the index value of the chromophore substituent of MPc in the solvent; thus, the concept can be used as a solvatochromic parameter to study a wide range of supramolecular and heterocyclic compounds that can be modified at their periphery or 'handles'. Particularly, in this study, the concept has been used to rank MPc candidates by using the statistical mean performance of the solvatochromic parameters, which are red shift index, polarizability efficiency and ASE. We hereby review the solvent effects on the UV/vis spectra of substituted and unsubstituted MPcs.

  • 33.
    Akpe, Victor
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Vernet, Erik
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Characterization studies of aluminum phthalocyanine binding to antibodies from SKBR 3 cell line2008Report (Other academic)
  • 34.
    Akpe, Victor
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Vernet, Erik
    KTH, School of Biotechnology (BIO), Protein Technology.
    Madu, Christian
    Obirai, Joseph C.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Understanding the Photochemical Pathway of In Vitro Target Delivery of Aluminium Phthalocyanine: A Mechanistic Approach Using Radical Reaction Chemistry2014In: ChemPlusChem, E-ISSN 2192-6506, Vol. 79, no 5, p. 671-679Article in journal (Refereed)
    Abstract [en]

    A classical dye, aluminium phthalocyanine (AlPc), is used to study the photochemical processes involved in the chromophore-assisted laser inactivation technique. Both cell-free and cell-based systems are investigated by novel methods and radical reaction chemistry. Findings on the photochemical pathways in two models representing cell-free and a cell-based systems are reported. In the cell-free system, the unsubstituted, free, fluorescence-active photosensitiser AlPc recovers its fluorescence signal by means of phosphorescence through a reversible photobleaching process. In the cell-based system, photoactivation of substituted AlPc conjugated to an antibody results in the loss of fluorescence signal at the area examined. Reinjection of the AlPc-conjugated antibodies restores the fluorescence signal.

  • 35. Aktas, Ozan
    et al.
    Ren, H.
    Runge, A. F. J.
    Peacock, A. C.
    Hawkins, T.
    Ballato, J.
    Gibson, Ursula J.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Interfacing telecom fibers and silicon core fibers with nano-spikes for in-fiber silicon devices2018In: 2018 Optical Fiber Communications Conference and Exposition, OFC 2018 - Proceedings, Institute of Electrical and Electronics Engineers Inc. (IEEE) , 2018, p. 1-3Conference paper (Refereed)
    Abstract [en]

    We report fabrication of tapered silicon core fibers with nano-spikes enabling efficient optical coupling into the core, as well as their seamless integration with single mode fibers. A proof-of-concept integrated in-fiber silicon device is demonstrated.

  • 36. Aktas, Ozan
    et al.
    Ren, H.
    Runge, A. F. J.
    Peacock, A. C.
    Hawkins, T.
    Ballato, J.
    Gibson, Ursula J.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Interfacing telecom fibers and silicon core fibers with nano-spikes for in-fiber silicon devices2018In: Optics InfoBase Conference Papers, Optics Info Base, Optical Society of America, 2018, article id u12d3i3mConference paper (Refereed)
    Abstract [en]

    We report fabrication of tapered silicon core fibers with nano-spikes enabling efficient optical coupling into the core, as well as their seamless integration with single mode fibers. A proof-of-concept integrated in-fiber silicon device is demonstrated. 

  • 37.
    Al Khabouri, Saja
    et al.
    Sultan Qaboos Univ, Dept Phys, POB 36, Muscat 123, Oman..
    Al Harthi, Salim
    Sultan Qaboos Univ, Dept Phys, POB 36, Muscat 123, Oman..
    Maekawa, Toru
    Toyo Univ, Bionano Elect Res Ctr, 2100 Kujirai, Kawagoe, Saitama 3508585, Japan..
    Elzain, Mohamed E.
    Sultan Qaboos Univ, Dept Phys, POB 36, Muscat 123, Oman..
    Kyaw, Htet Htet
    Sultan Qaboos Univ, Nanotechnol Res Ctr, POB 33, Muscat 123, Oman..
    Myint, Myo Tay Zar
    Sultan Qaboos Univ, Dept Phys, POB 36, Muscat 123, Oman..
    Laxman, Karthik
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Structure, composition and enhanced magnetic properties of novel ternary multicore-shell Ni-Co-Cr nanoclusters prepared by one-step inert gas condensation method2021In: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 271, article id 124858Article in journal (Refereed)
    Abstract [en]

    We have synthesized ternary Ni-Co-Cr nanoclusters using one step method by simultaneous sputtering of metallic targets through inert gas condensation (IGC) deposition process. The difference in surface energy between the component atoms creates a preferential surface phase leading to the formation of multi core/shell structures. Surface structure and composition analysis reveal metallic and oxide phases characterized by extraordinary 1.43 mu m periodicity strong magnetic stripe domains with weak magnetic force microscopy signal attenuation up to a lift height value of 2.5 mu m. In addition, the ternary nanoclusters exhibit strong ferromagnetic behavior below the blocking temperature of 139 K with coercivity of 700 Oe at 4 K. The enhanced magnetic properties are attributed to Volmer-Weber growth mechanism and pave a facile way for preparing ternary core/ shell magnetic structures needed for applications which require strong magnetic anisotropy along their growth direction.

  • 38.
    Al Soubaihi, Rola Mohammad
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Saoud, Khaled Mohammad
    Virginia Commonwealth Univ Qatar, Liberal Arts & Sci Program, POB 8095, Doha, Qatar..
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Critical Review of Low-Temperature CO Oxidation and Hysteresis Phenomenon on Heterogeneous Catalysts2018In: Catalysts, E-ISSN 2073-4344, Vol. 8, no 12, article id 660Article, review/survey (Refereed)
    Abstract [en]

    There is a growing demand for new heterogeneous catalysts for cost-effective catalysis. Currently, the hysteresis phenomenon during low-temperature CO oxidation is an important topic in heterogeneous catalysis. Hysteresis provides important information about fluctuating reaction conditions that affect the regeneration of active sites and indicate the restoration of catalyst activity. Understanding its dynamic behavior, such as hysteresis and self-sustained kinetic oscillations, during CO oxidation, is crucial for the development of cost-effective, stable and long-lasting catalysts. Hysteresis during CO oxidation has a direct influence on many industrial processes and its understanding can be beneficial to a broad range of applications, including long-life CO2 lasers, gas masks, catalytic converters, sensors, indoor air quality, etc. This review considers the most recent reported advancements in the field of hysteresis behavior during CO oxidation which shed light on the origin of this phenomenon and the parameters that influence the type, shape, and width of the conversion of the hysteresis curves.

  • 39.
    Al Soubaihi, Rola Mohammad
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Saoud, Khaled Mohammad
    Virginia Commonwealth Univ Qatar, Liberal Arts & Sci Program, Doha, Qatar..
    Myint, Myo Tay Zar
    Sultan Qaboos Univ, Coll Sci, Dept Phys, POB 36, Muscat 123, Oman..
    Göthelid, Mats A.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst2021In: Catalysts, E-ISSN 2073-4344, Vol. 11, no 1, article id 131Article in journal (Refereed)
    Abstract [en]

    Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (T-ig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than T-ig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at T-ig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.

  • 40. Al-Abri, M.
    et al.
    Al-Ghafri, B.
    Bora, T.
    Dobretsov, S.
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Castelletto, S.
    Rosa, L.
    Boretti, A.
    Chlorination disadvantages and alternative routes for biofouling control in reverse osmosis desalination2019In: npj Clean Water, ISSN 2059-7037, Vol. 2, no 1, article id 2Article in journal (Refereed)
    Abstract [en]

    With an ever-increasing human population, access to clean water for human use is a growing concern across the world. Seawater desalination to produce usable water is essential to meet future clean water demand. Desalination processes, such as reverse osmosis and multi-stage flash have been implemented worldwide. Reverse osmosis is the most effective technology, which uses a semipermeable membrane to produce clean water under an applied pressure. However, membrane biofouling is the main issue faced by such plants, which requires continuous cleaning or regular replacement of the membranes. Chlorination is the most commonly used disinfection process to pretreat the water to reduce biofouling. Although chlorination is widely used, it has several disadvantages, such as formation of disinfection by-products and being ineffective against some types of microbes. This review aims to discuss the adverse effect of chlorination on reverse osmosis membranes and to identify other possible alternatives of chlorination to reduce biofouling of the membranes. Reverse osmosis membrane degradation and mitigation of chlorines effects, along with newly emerging disinfection technologies, are discussed, providing insight to both academic institutions and industries for the design of improved reverse osmosis systems. 

  • 41.
    Al-Abri, Mohammed
    et al.
    Sultan Qaboos Univ, Dept Chem & Petr Engn, Coll Engn, POB 33, Al Khoud 123, Oman.;Sultan Qaboos Univ, Nanotechnol Res Ctr, POB 17, Al Khoud 123, Oman..
    Al-Ghafri, Buthayna
    Sultan Qaboos Univ, Nanotechnol Res Ctr, POB 17, Al Khoud 123, Oman..
    Bora, Tanujjal
    Asian Inst Technol, Ctr Excellence Nanotechnol, POB 4, Klong Luangpathumthani 12120, Thailand..
    Dobretsov, Sergey
    Sultan Qaboos Univ, Dept Marine Sci & Fisheries, Coll Agr & Marine Sci, POB 34, Al Khoud 123, Oman.;Sultan Qaboos Univ, Ctr Excellence Marine Biotechnol, POB 50, Muscat 123, Oman..
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Castelletto, Stefania
    RMIT Univ, Sch Engn, Bundoora, Vic 3083, Australia..
    Rosa, Lorenzo
    Univ Modena & Reggio Emilia, Dept Engn Enzo Ferrari, Via Vivarelli 10, I-41125 Modena, Italy..
    Boretti, Albert
    14 Chancellor Ave, Bundoora, Vic 3083, Australia..
    Chlorination disadvantages and alternative routes for biofouling control in reverse osmosis desalination (vol 2, 2, 2019)2019In: NPJ CLEAN WATER, ISSN 2059-7037, Vol. 2, article id 8Article in journal (Refereed)
  • 42. Alaghmandfard, A.
    et al.
    Sedighi, O.
    Tabatabaei Rezaei, N.
    Abedini, A. A.
    Malek Khachatourian, A.
    Toprak, Muhammet
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Seifalian, A.
    Recent advances in the modification of carbon-based quantum dots for biomedical applications2021In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 120, article id 111756Article, review/survey (Refereed)
    Abstract [en]

    Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface functionalization, polymer capping, nano-composite and core-shell structures, and the drawbacks and challenges in each of these methods are discussed.

  • 43.
    Alarcon, Aixa
    et al.
    Johnson Johnson Surg Vision Inc, Groningen, Netherlands..
    Canovas, Carmen
    Johnson Johnson Surg Vision Inc, Groningen, Netherlands..
    Van der Mooren, Marrie
    Johnson Johnson Surg Vision Inc, Groningen, Netherlands..
    Janakiraman, Priya
    Johnson Johnson Surg Vision Inc, Groningen, Netherlands..
    Rosen, Robert
    Johnson Johnson Surg Vision Inc, Groningen, Netherlands..
    Lundström, Linda
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Chang, Daniel H.
    Empire Eye Laser Ctr, Bakersfield, CA USA..
    Clinical measurements of peripheral contrast sensitivity in elderly phakic and pseudophakic eyes2022In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 63, no 7Article in journal (Other academic)
  • 44.
    Alattar, Ahmad
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Photo-Fenton Activity of a Prussian Blue Analogue Nanocomposite for Biomass Reforming2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the wake of an escalating environmental crisis, underscored by global warming and its profound impacts on our planet, the quest for innovative solutions has never been more critical. This urgency propels the exploration of new materials and sustainable innovations to revolutionize energy and environmental remediation technologies. This study delves into the performance of Zinc Oxide (ZnO) and Titanium Dioxide (TiO2) nanorods, alongside a Co-Fe Prussian Blue Analogue (PBA) nanocomposite, within photofenton-like reactors aimed at wastewater treatment and hydrogen gas production from cellulose. Through a detailed literature review and subsequent experiments, it becomes evident that ZnO nanorods, with their approximate length of 800 nm, and TiO2 nanorods, measuring around 1 µm, exhibit photocatalytic degradation capabilities in a near-neutral environment (pH = 6). Specifically, 1 mg/ml of TiO2-PBA was capable of decomposing 92% of 10 ppm of Rhodamine B in 40 minutes with the aid of just 0.5 mM of persulfate (Peroxydisulfate, PDS), while the photoreforming of rapeseed cellulose with 4 mM of persulfate results in the production of 90 mmol/gh of hydrogen. Furthermore, the study illuminates the distinctive Fenton-like behavior and proton conductivity of Co-Fe PBA nanocubes without the aid of noble metals like Platinum (Pt), underlining their critical role in advanced oxidation processes. This study reveals how semiconductor materials interact with reactive oxidative species to efficiently degrade pollutants and produce hydrogen, highlighting significant advancements in water purification and sustainable energy solutions. By advancing our understanding of these photocatalytic systems, this research contributes significantly to the global efforts aimed at environmental preservation and energy sustainability, marking a pivotal step towards mitigating the adverse effects of climate change through innovative technological advancements.

  • 45.
    Al-attar, Nebras
    et al.
    School of biosystems and food Engineering, University of Technology, Baghdad, 10066, Iraq; Laser and Optoelectronics Engineering Department, University of Technology, Baghdad, 10066, Iraq.
    Al-Shammari, Rusul M.
    School of Physics, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland; Conway Institute of Biomolecular and Biomedical Research, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rodriguez, Brian J.
    School of Physics, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland; Conway Institute of Biomolecular and Biomedical Research, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland.
    Rice, James H.
    School of Physics, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland.
    Wide-field surface-enhanced Raman scattering from ferroelectrically defined Au nanoparticle microarrays for optical sensing2018In: Proceedings CLEO: Applications and Technology 2018, Optica Publishing Group , 2018Conference paper (Refereed)
    Abstract [en]

    The acquisition-time in optical sensors using SERS is vital value. Wide-field SERS is used to perform high-density of hot-spots of GNPs photodeposition on a periodically-protonexchanged- LiNbO3 which, leads to increase the sensitivity at ultralow probe concentrations.

  • 46.
    Albertsson, Dagur Ingi
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electronics and Embedded systems, Integrated devices and circuits.
    Zahedinejad, Mohammad
    Department of Physics, University of Gothenburg.
    Åkerman, Johan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics. Department of Physics, University of Gothenburg.
    Rodriguez, Saul
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electronics and Embedded systems, Integrated devices and circuits.
    Rusu, Ana
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electronics and Embedded systems, Integrated devices and circuits.
    Compact Macrospin-Based Model of Three-Terminal Spin-Hall Nano Oscillators2019In: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 55, no 10, article id 4003808Article in journal (Refereed)
    Abstract [en]

    Emerging spin-torque nano oscillators (STNOs) and spin-Hall nano oscillators (SHNOs) are potential candidates for microwave applications. Recent advances in three-terminal magnetic tunnel junction (MTJ)-based SHNOs opened the possibility to develop more reliable and well-controlled oscillators, thanks to individual spin Hall-driven precession excitation and read-out paths. To develop hybrid systems by integrating three-terminal SHNOs and CMOS circuits, an electrical model able to capture the analog characteristics of three-terminal SHNOs is needed. This model needs to be compatible with current electric design automation (EDA) tools. This work presents a comprehensive macrospin-based model of three-terminal SHNOs able to describe the dc operating point, frequency modulation, phase noise, and output power. Moreover, the effect of voltage-controlled magnetic anisotropy (VCMA) is included. The model shows good agreement with experimental measurements and could be used in developing hybrid three-terminal SHNO/CMOS systems.

    Download full text (pdf)
    fulltext
  • 47.
    Albertsson, Ingrid
    et al.
    Stockholm Univ, Dept Biochem & Biophys, Svante Arrhenius Vag 16C, SE-10691 Stockholm, Sweden..
    Sjöholm, Johannes
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    ter Beek, Josy
    Stockholm Univ, Dept Biochem & Biophys, Svante Arrhenius Vag 16C, SE-10691 Stockholm, Sweden.;Umea Univ, Dept Med Biochem & Biophys, SE-90187 Umea, Sweden..
    Watmough, Nicholas J.
    Univ East Anglia, Sch Biol Sci, Norwich Res Pk, Norwich NR4 7TJ, Norfolk, England..
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Adelroth, Pia
    Stockholm Univ, Dept Biochem & Biophys, Svante Arrhenius Vag 16C, SE-10691 Stockholm, Sweden..
    Functional interactions between nitrite reductase and nitric oxide reductase from Paracoccus denitrificans2019In: Scientific Reports, E-ISSN 2045-2322, Vol. 9, article id 17234Article in journal (Refereed)
    Abstract [en]

    Denitrification is a microbial pathway that constitutes an important part of the nitrogen cycle on earth. Denitrifying organisms use nitrate as a terminal electron acceptor and reduce it stepwise to nitrogen gas, a process that produces the toxic nitric oxide (NO) molecule as an intermediate. In this work, we have investigated the possible functional interaction between the enzyme that produces NO; the cd(1) nitrite reductase (cd(1)NiR) and the enzyme that reduces NO; the c-type nitric oxide reductase (cNOR), from the model soil bacterium P. denitrificans. Such an interaction was observed previously between purified components from P. aeruginosa and could help channeling the NO (directly from the site of formation to the side of reduction), in order to protect the cell from this toxic intermediate. We find that electron donation to cNOR is inhibited in the presence of cd(1)NiR, presumably because cd(1)NiR binds cNOR at the same location as the electron donor. We further find that the presence of cNOR influences the dimerization of cd(1)NiR. Overall, although we find no evidence for a high-affinity, constant interaction between the two enzymes, our data supports transient interactions between cd(1)NiR and cNOR that influence enzymatic properties of cNOR and oligomerization properties of cd(1)NiR. We speculate that this could be of particular importance in vivo during metabolic switches between aerobic and denitrifying conditions.

  • 48.
    Alcusa-Saez, E. P.
    et al.
    ICMUV, Dept Fis Aplicada & Electromagnetismo, Dr Moliner 50, Burjassot 46100, Spain..
    Diez, A.
    ICMUV, Dept Fis Aplicada & Electromagnetismo, Dr Moliner 50, Burjassot 46100, Spain..
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics. Acreo AB, Dept Fiber Photon, Elect 236, S-16440 Kista, Sweden..
    Norin, Lars
    KTH, School of Engineering Sciences (SCI), Applied Physics. Acreo AB, Dept Fiber Photon, Elect 236, S-16440 Kista, Sweden..
    Andres, M. V.
    ICMUV, Dept Fis Aplicada & Electromagnetismo, Dr Moliner 50, Burjassot 46100, Spain..
    Acousto-optic interaction in polyimide coated optical fibers2017In: 2017 CONFERENCE ON LASERS AND ELECTRO-OPTICS EUROPE & EUROPEAN QUANTUM ELECTRONICS CONFERENCE (CLEO/EUROPE-EQEC), IEEE , 2017Conference paper (Refereed)
  • 49. Alcusa-Saez, E. P.
    et al.
    Diez, A.
    Rivera-Perez, E.
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Norin, Lars
    ACREO.
    Andres, M. V.
    Acousto-optic interaction in polyimide coated optical fibers with flexural waves2017In: Optics Express, E-ISSN 1094-4087, Vol. 25, no 15, p. 17167-17173Article in journal (Refereed)
    Abstract [en]

    Acousto-optic coupling in polyimide-coated single-mode optical fibers using flexural elastic waves is demonstrated. The effect of the polyimide coating on the acoustooptic interaction process is analyzed in detailed. Theoretical and experimental results are in good agreement. Although the elastic attenuation is significant, we show that acousto-optic coupling can be produced with a reasonably good efficiency. To our knowledge, it is the first experimental demonstration of acousto-optic coupling in optical fibers with robust protective coating.

  • 50. Alcusa-Saez, E. P.
    et al.
    Diez, A.
    Rivera-Perez, E.
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Norin, Lars
    Andres, M. V.
    All-fiber acousto-optic tunable filter in polyimide coated optical fibers2017In: 2017 19th International Conference on Transparent Optical Networks (ICTON), IEEE Computer Society, 2017, article id 8025093Conference paper (Refereed)
    Abstract [en]

    We present the experimental demonstration of in-fiber acousto-optic coupling in a polyimide-coated optical fiber. Although the presence of the polyimide coating increases is significantly the attenuation of the acoustic wave, we show that acousto-optic interaction can still be produced with reasonable efficiency. The effect of the polyimide coating on the acousto-optic interaction process is analyzed in detailed. Theoretical and experimental results are in good agreement. To our knowledge, this is the first experimental demonstration of acousto-optic coupling in optical fibers with robust protective coating.

1234567 1 - 50 of 4487
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf