1,316 results on '"Toppari J"'
Search Results
2. Thermal disorder prevents the suppression of ultra-fast photochemistry in the strong light-matter coupling regime
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Dutta, Arpan, Tiainen, Ville, Sokolovskii, Ilia, Duarte, Luís, Markešević, Nemanja, Morozov, Dmitry, Qureshi, Hassan A., Pikker, Siim, Groenhof, Gerrit, and Toppari, J. Jussi
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- 2024
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3. Polariton response in the presence of Brownian dissipation from molecular vibrations
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Kansanen, Kalle S. U., Toppari, J. Jussi, and Heikkilä, Tero T.
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Quantum Physics ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We study the elastic response of a stationarily driven system of a cavity field strongly coupled with molecular excitons, taking into account the main dissipation channels due to the finite cavity linewidth and molecular vibrations. We show that the frequently used coupled oscillator model fails in describing this response especially due to the non-Lorentzian dissipation of the molecules to their vibrations. Signatures of this failure are the temperature dependent minimum point of the polariton peak splitting, uneven polariton peak height at the minimum splitting, and the asymmetric shape of the polariton peaks even at the experimentally accessed "zero-detuning" point. Using a rather generic yet representative model of molecular vibrations, we predict the polariton response in various conditions, depending on the temperature, molecular Stokes shift and vibration frequencies, and the size of the Rabi splitting. Our results can be used as a sanity check of the experiments trying to "prove" results originating from strong coupling, such as vacuum-enhanced chemical reaction rate., Comment: 11 pages, 7 figures
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- 2020
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4. Theory for the stationary polariton response in the presence of vibrations
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Kansanen, K. S. U., Asikainen, A., Toppari, J. J., Groenhof, G., and Heikkilä, T. T.
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Quantum Physics ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We construct a model describing the response of a hybrid system where the electromagnetic field - in particular, surface plasmon polaritons - couples strongly with electronic excitations of atoms or molecules. Our approach is based on the input-output theory of quantum optics, and in particular it takes into account the thermal and quantum vibrations of the molecules. The latter is described within the $P(E)$ theory analogous to that used in the theory of dynamical Coulomb blockade. As a result, we are able to include the effect of the molecular Stokes shift on the strongly coupled response of the system. Our model then accounts for the asymmetric emission from upper and lower polariton modes. It also allows for an accurate description of the partial decoherence of the light emission from the strongly coupled system. Our results can be readily used to connect the response of the hybrid modes to the emission and fluorescence properties of the individual molecules, and thus are relevant in understanding any utilization of such systems, like coherent light harvesting., Comment: 13 pages, 6 figures; included comparison between theory and experiment
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- 2019
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5. Ultra-fast photochemistry in the strong light-matter coupling regime
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Dutta, Arpan, primary, Tiainen, Ville, additional, Duarte, Luis, additional, Markesevic, Nemanja, additional, Sokolovskii, Ilia, additional, Morozov, Dmitry, additional, Qureshi, Hassan A., additional, Pikker, Siim, additional, Groenhof, Gerrit, additional, and Toppari, J. Jussi, additional
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- 2024
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6. Antiviral action of a functionalized plastic surface against human coronaviruses
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Shroff, Sailee, Haapakoski, Marjo, Tapio, Kosti, Laajala, Mira, Leppanen, Miika, Plavec, Zlatka, Haapala, Antti, Butcher, Sarah J., Ihalainen, Janne A., Toppari, J. Jussi, Marjomaki, Varpu, Shroff, Sailee, Haapakoski, Marjo, Tapio, Kosti, Laajala, Mira, Leppanen, Miika, Plavec, Zlatka, Haapala, Antti, Butcher, Sarah J., Ihalainen, Janne A., Toppari, J. Jussi, and Marjomaki, Varpu
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Viruses may persist on solid surfaces for long periods, which may contribute to indirect transmission. Thus, it is imperative to develop functionalized surfaces that will lower the infectious viral load in everyday life. Here, we have tested a plastic surface functionalized with tall oil rosin against the seasonal human coronavirus OC43 as well as severe acute respiratory syndrome coronavirus 2. All tested non-functionalized plastic surfaces showed virus persistence up to 48 h. In contrast, the functionalized plastic showed good antiviral action already within 15 min of contact and excellent efficacy after 30 min over 90% humidity. Excellent antiviral effects were also observed at lower humidities of 20% and 40%. Despite the hydrophilic nature of the functionalized plastic, viruses did not adhere strongly to it. According to helium ion microscopy, viruses appeared flatter on the rosin-functionalized surface, but after flushing away from the rosin-functionalized surface, they showed no apparent structural changes when imaged by transmission electron microscopy of cryogenic or negatively stained specimens or by atomic force microscopy. Flushed viruses were able to bind to their host cell surface and enter endosomes, suggesting that the fusion with the endosomal membrane was halted. The eluted rosin from the functionalized surface demonstrated its ability to inactivate viruses, indicating that the antiviral efficacy relied on the active leaching of the antiviral substances, which acted on the viruses coming into contact. The rosin-functionalized plastic thus serves as a promising candidate as an antiviral surface for enveloped viruses.IMPORTANCEDuring seasonal and viral outbreaks, the implementation of antiviral plastics can serve as a proactive strategy to limit the spread of viruses from contaminated surfaces, complementing existing hygiene practices. In this study, we show the efficacy of a rosin-functionalized plastic surface that kills the viral infectivity of hum
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- 2024
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7. Antiviral action of a functionalized plastic surface against human coronaviruses
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Shroff, Sailee, primary, Haapakoski, Marjo, additional, Tapio, Kosti, additional, Laajala, Mira, additional, Leppänen, Miika, additional, Plavec, Zlatka, additional, Haapala, Antti, additional, Butcher, Sarah J., additional, Ihalainen, Janne A., additional, Toppari, J. Jussi, additional, and Marjomäki, Varpu, additional
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- 2024
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8. Manufacturing doubt about endocrine disrupter science - A rebuttal of industry-sponsored critical comments on the UNEP/WHO report "State of the Science of Endocrine Disrupting Chemicals 2012"
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Bergman, Å, Becher, G, Blumberg, B, Bjerregaard, P, Bornman, R, Brandt, I, Casey, SC, Frouin, H, Giudice, LC, Heindel, JJ, Iguchi, T, Jobling, S, Kidd, KA, Kortenkamp, A, Lind, PM, Muir, D, Ochieng, R, Ropstad, E, Ross, PS, Skakkebaek, NE, Toppari, J, Vandenberg, LN, Woodruff, TJ, and Zoeller, RT
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Toxicology ,Pharmacology and Pharmaceutical Sciences - Abstract
We present a detailed response to the critique of "State of the Science of Endocrine Disrupting Chemicals 2012" (UNEP/WHO, 2013) by financial stakeholders, authored by Lamb et al. (2014). Lamb et al.'s claim that UNEP/WHO (2013) does not provide a balanced perspective on endocrine disruption is based on incomplete and misleading quoting of the report through omission of qualifying statements and inaccurate description of study objectives, results and conclusions. Lamb et al. define extremely narrow standards for synthesizing evidence which are then used to dismiss the UNEP/WHO 2013 report as flawed. We show that Lamb et al. misuse conceptual frameworks for assessing causality, especially the Bradford-Hill criteria, by ignoring the fundamental problems that exist with inferring causality from empirical observations. We conclude that Lamb et al.'s attempt of deconstructing the UNEP/WHO (2013) report is not particularly erudite and that their critique is not intended to be convincing to the scientific community, but to confuse the scientific data. Consequently, it promotes misinterpretation of the UNEP/WHO (2013) report by non-specialists, bureaucrats, politicians and other decision makers not intimately familiar with the topic of endocrine disruption and therefore susceptible to false generalizations of bias and subjectivity.
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- 2015
9. Identifying yeasts using surface enhanced Raman spectroscopy
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Lemma, Tibebe, Wang, Jin, Arstila, Kai, Hytönen, Vesa P., and Toppari, J. Jussi
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- 2019
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10. Direct optical measurement of light coupling into planar waveguide by plasmonic nanoparticles
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Pennanen, Antti M. and Toppari, J. Jussi
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Physics - Optics - Abstract
Coupling of light into a thin layer of high refractive index material by plasmonic nanoparticles has been widely studied for application in photovoltaic devices, such as thin-film solar cells. In numerous studies this coupling has been investigated through measurement of e.g. quantum efficiency or photocurrent enhancement. Here we present a direct optical measurement of light coupling into a waveguide by plasmonic nanoparticles. We investigate the coupling efficiency into the guided modes within the waveguide by illuminating the surface of a sample, consisting of a glass slide coated with a high refractive index planar waveguide and plasmonic nanoparticles, while directly measuring the intensity of the light emitted out of the waveguide edge. These experiments were complemented by transmittance and reflectance measurements. We show that the light coupling is strongly affected by thin-film interference, localized surface plasmon resonances of the nanoparticles and the illumination direction (front or rear)., Comment: 13 pages, 7 figures. This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: [http://dx.doi.org/10.1364/OE.21.000A23] Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject
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- 2012
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11. Growth of immobilized DNA by polymerase: bridging nanoelectrodes with individual dsDNA molecules
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Linko, Veikko, Leppiniemi, Jenni, Shen, Boxuan, Niskanen, Einari, Hytönen, Vesa P., and Toppari, J. Jussi
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Physics - Biological Physics ,Condensed Matter - Other Condensed Matter ,Condensed Matter - Soft Condensed Matter - Abstract
We present a method for controlled connection of gold electrodes with dsDNA molecules (locally on a chip) by utilizing polymerase to elongate single-stranded DNA primers attached to the electrodes. Thiol-modified oligonucleotides are directed and immobilized to nanoscale electrodes by means of dielectrophoretic trapping, and extended in a procedure mimicking PCR, finally forming a complete dsDNA molecule bridging the gap between the electrodes. The technique opens up opportunities for building from the bottom-up, for detection and sensing applications, and also for molecular electronics., Comment: 5 pages, 3 figures; Nanoscale (2011)
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- 2011
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12. Vacuum Rabi splitting and strong coupling dynamics for surface plasmon polaritons and Rhodamine 6G molecules
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Hakala, T. K., Toppari, J. J., Kuzyk, A., Pettersson, M., Tikkanen, H., Kunttu, H., and Törmä, P.
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Physics - Optics - Abstract
We report on strong coupling between surface plasmon polaritons (SPP) and Rhodamine 6G (R6G) molecules, with double vacuum Rabi splitting energies up to 230 and 110 meV. In addition, we demonstrate the emission of all three energy branches of the strongly coupled SPP-exciton hybrid system, revealing features of system dynamics that are not visible in conventional reflectometry. Finally, in analogy to tunable-Q microcavities, we show that the Rabi splitting can be controlled by adjusting the interaction time between waveguided SPPs and R6G deposited on top of the waveguide. The interaction time can be controlled with sub-fs precision by adjusting the length of the R6G area with standard lithography methods., Comment: 4 pages, 4 figures
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- 2009
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13. P08-07: Imatinib Decreases DNA synthesis, germ cell survival, and stem cell proliferation and differentiation in rodent testis
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Eggert, A., primary, Mäkelä, J.-A., additional, Nurmio, M., additional, Leskinen, S., additional, Wahlgren, A., additional, Jahnukainen, K., additional, Kotaja, N., additional, and Toppari, J., additional
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- 2023
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14. Method for finding the critical temperature of the island in a SET structure
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Toppari, J. J., Kühn, T., Halvari, A. P., and Paraoanu, G. S.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Physics - Instrumentation and Detectors - Abstract
We present a method to measure the critical temperature of the island of a superconducting single electron transistor. The method is based on a sharp change in the slope of the zero-bias conductance as a function of temperature. We have used this method to determine the superconducting phase transition temperature of the Nb island of an superconducting single electron transistor with Al leads. We obtain $T_\mathrm{c}^\mathrm{Nb}$ as high as 8.5 K and gap energies up to $\Delta_\mathrm{Nb}\simeq 1.45$ meV. By looking at the zero bias conductance as a function of magnetic field instead of temperature, also the critical field of the island can be determined. Using the orthodox theory, we have performed extensive numerical simulations of charge transport properties in the SET at temperatures comparable to the gap, which match very well the data, therefore providing a solid theoretical basis for our method., Comment: 4 pages, 2 figures
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- 2008
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15. High-Yield of Memory Elements from Carbon Nanotube Field-Effect Transistors with Atomic Layer Deposited Gate Dielectric
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Rinkiö, Marcus, Johansson, Andreas, Zavodchikova, Marina Y., Toppari, J. Jussi, Nasibulin, Albert G., Kauppinen, Esko I., and Törmä, Päivi
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science - Abstract
Carbon nanotube field-effect transistors (CNT FETs) have been proposed as possible building blocks for future nano-electronics. But a challenge with CNT FETs is that they appear to randomly display varying amounts of hysteresis in their transfer characteristics. The hysteresis is often attributed to charge trapping in the dielectric layer between the nanotube and the gate. This study includes 94 CNT FET samples, providing an unprecedented basis for statistics on the hysteresis seen in five different CNT-gate configurations. We find that the memory effect can be controlled by carefully designing the gate dielectric in nm-thin layers. By using atomic layer depositions (ALD) of HfO$_{2}$ and TiO$_{2}$ in a triple-layer configuration, we achieve the first CNT FETs with consistent and narrowly distributed memory effects in their transfer characteristics., Comment: 6 pages, 3 figures; added one reference, text reformatted with smaller additions
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- 2008
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16. Molecular coupling of light with plasmonic waveguides
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Kuzyk, Anton, Pettersson, Mika, Toppari, J. Jussi, Hakala, Tommi K., Tikkanen, Hanna, Kunttu, Henrik, and Torma, Paivi
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Physics - Optics ,Physics - Chemical Physics - Abstract
We use molecules to couple light into and out of microscale plasmonic waveguides. Energy transfer, mediated by surface plasmons, from donor molecules to acceptor molecules over ten micrometer distances is demonstrated. Also surface plasmon coupled emission from the donor molecules is observed at similar distances away from the excitation spot. The lithographic fabrication method we use for positioning the dye molecules allows scaling to nanometer dimensions. The use of molecules as couplers between far-field and near-field light offers the advantages that no special excitation geometry is needed, any light source can be used to excite plasmons and the excitation can be localized below the diffraction limit. Moreover, the use of molecules has the potential for integration with molecular electronics and for the use of molecular self-assembly in fabrication. Our results constitute a proof-of-principle demonstration of a plasmonic waveguide where signal in- and outcoupling is done by molecules., Comment: 9 pages, 5 figures
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- 2007
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17. A hybrid method for calorimetry with subnanolitre samples using Schottky junctions
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Hakala, T. K., Toppari, J. J., and Torma, P.
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Physics - Instrumentation and Detectors - Abstract
A micrometer scale calorimeter realized by using Schottky junctions as a thermometer is presented. Combined with a hybrid experimental method, it enables simultaneous time-resolved measurements of variations in both the energy and the heat capacity of subnanolitre samples., Comment: 6 pages, 6 figures
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- 2007
18. Trapping of 27 bp - 8 kbp DNA and immobilization of thiol-modified DNA using dielectrophoresis
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Tuukkanen, Sampo, Kuzyk, Anton, Toppari, J. Jussi, Hakkinen, Hannu, Hytonen, Vesa P., Niskanen, Einari, Rinkio, Marcus, and Torma, Paivi
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Condensed Matter - Other Condensed Matter ,Condensed Matter - Soft Condensed Matter ,Physics - Biological Physics ,Quantitative Biology - Biomolecules - Abstract
Dielectrophoretic trapping of six different DNA fragments, sizes varying from the 27 to 8416 bp, has been studied using confocal microscopy. The effect of the DNA length and the size of the constriction between nanoscale fingertip electrodes on the trapping efficiency have been investigated. Using finite element method simulations in conjunction with the analysis of the experimental data, the polarizabilities of the different size DNA fragments have been calculated for different frequencies. Also the immobilization of trapped hexanethiol- and DTPA-modified 140 nm long DNA to the end of gold nanoelectrodes was experimentally quantified and the observations were supported by density functional theory calculations., Comment: 17 pages (1 column version), 8 figures
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- 2006
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19. Carbon Nanotubes as Electrodes for Dielectrophoresis of DNA
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Tuukkanen, Sampo, Toppari, J. Jussi, Kuzyk, Anton, Hirviniemi, Lasse, Hytonen, Vesa P., Ihalainen, Teemu, and Torma, Paivi
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Condensed Matter - Soft Condensed Matter ,Physics - Biological Physics ,Quantitative Biology - Biomolecules - Abstract
Dielectrophoresis can potentially be used as an efficient trapping tool in the fabrication of molecular devices. For nanoscale objects, however, the Brownian motion poses a challenge. We show that the use of carbon nanotube electrodes makes it possible to apply relatively low trapping voltages and still achieve high enough field gradients for trapping nanoscale objects, e.g., single molecules. We compare the efficiency and other characteristics of dielectrophoresis between carbon nanotube electrodes and lithographically fabricated metallic electrodes, in the case of trapping nanoscale DNA molecules. The results are analyzed using finite element method simulations and reveal information about the frequency dependent polarizability of DNA., Comment: 5 pages with 6 figures
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- 2006
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20. Dielectrophoresis of nanoscale dsDNA and humidity effects on its electrical conductivity
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Tuukkanen, S., Kuzyk, A., Toppari, J. J., Hytonen, V. P., Ihalainen, T., and Torma, P.
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Condensed Matter - Soft Condensed Matter ,Condensed Matter - Other Condensed Matter ,Physics - Biological Physics ,Quantitative Biology - Biomolecules ,Quantitative Biology - Other Quantitative Biology - Abstract
The dielectrophoresis method for trapping and attaching nanoscale double-stranded DNA between nanoelectrodes was developed. The method gives a high yield of trapping single or a few molecules only which enables transport measurements at the single molecule level. Electrical conductivity of individual 140-nm-long DNA molecules was measured, showing insulating behavior in dry conditions. In contrast, clear enhancement of conductivity was observed in moist conditions, relating to the interplay between the conformation of DNA molecules and their conductivity., Comment: 4 pages, 2 figures
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- 2005
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21. Cooper-pair resonances and subgap Coulomb blockade in a superconducting single-electron transistor
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Toppari, J. J., Kuhn, T., Halvari, A. P., Kinnunen, J., Leskinen, M., and Paraoanu, G. S.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Superconductivity - Abstract
We have fabricated and measured superconducting single-electron transistors with Al leads and Nb islands. At bias voltages below the gap of Nb we observe clear signatures of resonant tunneling of Cooper pairs, and of Coulomb blockade of the subgap currents due to linewidth broadening of the energy levels in the superconducting density of states of Nb. The experimental results are in good agreement with numerical simulations., Comment: 4 pages, 3 figures
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- 2003
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22. Turnstile behaviour of the Cooper-pair pump
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Toppari, J. J., Kivioja, J. M., Pekola, J. P., and Savolainen, M. T.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Superconductivity - Abstract
We have experimentally studied the behaviour of the so-called Cooper pair pump (CPP) with three Josephson junctions, in the limit of small Josephson coupling EJ < EC. These experiments show that the CPP can be operated as a traditional turnstile device yielding a gate-induced current 2ef in the direction of the bias voltage, by applying an RF-signal with frequency f to the two gates in phase, while residing at the degeneracy node of the gate plane. Accuracy of the CPP during this kind of operation was about 3% and the fundamental Landau-Zener limit was observed to lie above 20 MHz. We have also measured the current pumped through the array by rotating around the degeneracy node in the gate plane. We show that this reproduces the turnstile-kind of behavior. To overcome the contradiction between the obtained e-periodic DC-modulation and a pure 2e-behaviour in the RF-measurements, we base our observations on a general principle that the system always minimises its energy. It suggests that if the excess quasiparticles in the system have a freedom to tunnel, they will organize themselves to the configuration yielding the highest current., Comment: 29 pages, 16 figures, uses REVTeX and graphicx-package
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- 2003
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23. Connecting Berry's phase and the pumped charge in a Cooper pair pump
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Aunola, M. and Toppari, J. J.
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Condensed Matter - Superconductivity - Abstract
The properties of the tunnelling-charging Hamiltonian of a Cooper pair pump are well understood in the regime of weak and intermediate Josephson coupling, i.e. when $E_{\mathrm{J}}\lesssim E_{\mathrm{C}}$. It is also known that Berry's phase is related to the pumped charge induced by the adiabatical variation of the eigenstates. We show explicitly that pumped charge in Cooper pair pump can be understood as a partial derivative of Berry's phase with respect to the phase difference $\phi$ across the array. The phase fluctuations always present in real experiments can also be taken into account, although only approximately. Thus the measurement of the pumped current gives reliable, yet indirect, information on Berry's phase. As closing remarks, we give the differential relation between Berry's phase and the pumped charge, and state that the mathematical results are valid for any observable expressible as a partial derivative of the Hamiltonian., Comment: 5 pages, 5 figures, RevTeX, Presentation has been clarified
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- 2003
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24. Science and policy on endocrine disrupters must not be mixed: A reply to a "common sense" intervention by toxicology journal editors
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Bergman, A, Andersson, AM, Becher, G, Van Den Berg, M, Blumberg, B, Bjerregaard, P, Bornehag, CG, Bornman, R, Brandt, I, Brian, JV, Casey, SC, Fowler, PA, Frouin, H, Giudice, LC, Iguchi, T, Hass, U, Jobling, S, Juul, A, Kidd, KA, Kortenkamp, A, Lind, M, Martin, OV, Muir, D, Ochieng, R, Olea, N, Norrgren, L, Ropstad, E, Ross, PS, Rudén, C, Scheringer, M, Skakkebaek, NE, Söder, O, Sonnenschein, C, Soto, A, Swan, S, Toppari, J, Tyler, CR, Vandenberg, LN, Vinggaard, AM, Wiberg, K, and Zoeller, RT
- Abstract
The "common sense" intervention by toxicology journal editors regarding proposed European Union endocrine disrupter regulations ignores scientific evidence and well-established principles of chemical risk assessment. In this commentary, endocrine disrupter experts express their concerns about a recently published, and is in our considered opinion inaccurate and factually incorrect, editorial that has appeared in several journals in toxicology. Some of the shortcomings of the editorial are discussed in detail. We call for a better founded scientific debate which may help to overcome a polarisation of views detrimental to reaching a consensus about scientific foundations for endocrine disrupter regulation in the EU. © 2013 Bergman et al.; licensee BioMed Central Ltd.
- Published
- 2013
25. Decoherence in circuits of small Josephson junctions
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Pekola, J. P. and Toppari, J. J.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Superconductivity - Abstract
We discuss dephasing by the dissipative electromagnetic environment and by measurement in circuits consisting of small Josephson junctions. We present quantitative estimates and determine in which case the circuit might qualify as a quantum bit. Specifically, we analyse a three junction Cooper pair pump and propose a measurement to determine the decoherence time $\tau_\phi$., Comment: 4 pages, 4 figures
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- 2001
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26. Arrays of Josephson junctions in an environment with vanishing impedance
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Aunola, M., Toppari, J. J., and Pekola, J. P.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Superconductivity - Abstract
The Hamiltonian operator for an unbiased array of Josephson junctions with gate voltages is constructed when only Cooper pair tunnelling and charging effects are taken into account. The supercurrent through the system and the pumped current induced by changing the gate voltages periodically are discussed with an emphasis on the inaccuracies in the Cooper pair pumping. Renormalisation of the Hamiltonian operator is used in order to reliably parametrise the effects due to inhomogeneity in the array and non-ideal gating sequences. The relatively simple model yields an explicit, testable prediction based on three experimentally motivated and determinable parameters., Comment: 13 pages, 9 figures, uses RevTeX and epsfig, Revised version, Better readability and some new results
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- 1999
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27. Adiabatic transport of Cooper pairs in arrays of Josephson junctions
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Pekola, J. P., Toppari, J. J., Aunola, M., Savolainen, M. T., and Averin, D. V.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Superconductivity - Abstract
We have developed a quantitative theory of Cooper pair pumping in gated one-dimensional arrays of Josephson junctions. The pumping accuracy is limited by quantum tunneling of Cooper pairs out of the propagating potential well and by direct supercurrent flow through the array. Both corrections decrease exponentially with the number N of junctions in the array, but give a serious limitation of accuracy for any practical array. The supercurrent at resonant gate voltages decreases with N only as sin(v/N)/N, where v is the Josephson phase difference across the array., Comment: 5 pages, 2 figures, LaTex2e, Uses Graphicx.sty, Some minor changes made
- Published
- 1999
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28. Ultra-fast photochemistry in the strong light-matter coupling regime
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Dutta, Arpan, primary, Tiainen, Ville, additional, Duarte, Luis, additional, Markesevic, Nemanja, additional, Morozov, Dmitry, additional, Qureshi, Hassan A., additional, Groenhof, Gerrit, additional, and Toppari, J. Jussi, additional
- Published
- 2023
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29. Effect of molecular concentration on excitonic nanostructure based refractive index sensing and near-field enhanced spectroscopy
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Dutta, Arpan, primary and Toppari, J. Jussi, additional
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- 2023
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30. Fabrication-friendly polarization-sensitive plasmonic grating for optimal surface-enhanced Raman spectroscopy
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Dutta, Arpan, Nuutinen, Tarmo, Alam, Khairul, Matikainen, Antti, Li, Peng, Hulkko, Eero, Toppari, J. Jussi, Lipsanen, Harri, and Kang, Guoguo
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- 2020
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31. Conjugation with carbon nanotubes improves the performance of mesoporous silicon as Li-ion battery anode
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Ikonen, Timo, Kalidas, Nathiya, Lahtinen, Katja, Isoniemi, Tommi, Toppari, J. Jussi, Vázquez, Ester, Herrero-Chamorro, M. Antonia, Fierro, José Luis G., Kallio, Tanja, and Lehto, Vesa-Pekka
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- 2020
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32. HLA‐DQ‐conferred risk for type 1 diabetes does not alter neutralizing antibody response to a widely used enterovirus vaccine, the poliovirus vaccine
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Sioofy‐Khojine, A. (Amir‐Babak), Lehtonen, J. P. (Jussi P.), Nurminen, N. (Noora), Laiho, J. E. (Jutta E.), Toppari, J. (Jorma), Veijola, R. (Riitta), Lempainen, J. (Johanna), Ilonen, J. (Jorma), Knip, M. (Mikael), Hyöty, H. (Heikki), Sioofy‐Khojine, A. (Amir‐Babak), Lehtonen, J. P. (Jussi P.), Nurminen, N. (Noora), Laiho, J. E. (Jutta E.), Toppari, J. (Jorma), Veijola, R. (Riitta), Lempainen, J. (Johanna), Ilonen, J. (Jorma), Knip, M. (Mikael), and Hyöty, H. (Heikki)
- Abstract
This study investigated whether children with HLA-DQ-conferred risk for type 1 diabetes (T1D) have an altered immune response to the widely-used enterovirus vaccine, namely poliovirus vaccine, and whether initiation of autoimmunity to pancreatic islets modulates this response. Neutralizing antibodies induced by the inactivated poliovirus vaccine against poliovirus type 1 (Salk) were analysed as a marker of protective immunity at the age of 18 months in a prospective birth cohort. No differences were observed in antibody titers between children with and without genetic risk for T1D (odds ratio [OR] = 0.90 [0.83, 1.06], p = 0.30). In the presence of the genetic risk, no difference was observed between children with and without islet autoimmunity (OR = 1.00 [0.78, 1.28], p = 1.00). This did not change when only children with the autoimmunity before 18 months of age were included in the analyses (OR = 1.00 [0.85, 1.18], p = 1.00). No effect was observed when groups were stratified based on autoantigen specificity of the first-appearing autoantibody (IAA or GADA). The children in each comparison group were matched for sex, calendar year and month of birth, and municipality. Accordingly, we found no indication that children who are at risk to develop islet autoimmunity would have a compromised humoral immune response which could have increased their susceptibility for enterovirus infections. In addition, the proper immune response supports the idea of testing novel enterovirus vaccines for the prevention of T1D among these individuals.
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- 2023
33. Quantifying the utility of islet autoantibody levels in the prediction of type 1 diabetes in children
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Ng, K. (Kenney), Anand, V. (Vibha), Stavropoulos, H. (Harry), Veijola, R. (Riitta), Toppari, J. (Jorma), Maziarz, M. (Marlena), Lundgren, M. (Markus), Waugh, K. (Kathy), Frohnert, B. I. (Brigitte I.), Martin, F. (Frank), Lou, O. (Olivia), Hagopian, W. (William), Achenbach, P. (Peter), f. t. (for the T1DI Study Group), Ng, K. (Kenney), Anand, V. (Vibha), Stavropoulos, H. (Harry), Veijola, R. (Riitta), Toppari, J. (Jorma), Maziarz, M. (Marlena), Lundgren, M. (Markus), Waugh, K. (Kathy), Frohnert, B. I. (Brigitte I.), Martin, F. (Frank), Lou, O. (Olivia), Hagopian, W. (William), Achenbach, P. (Peter), and f. t. (for the T1DI Study Group)
- Abstract
Aims/hypothesis: The aim of this study was to explore the utility of islet autoantibody (IAb) levels for the prediction of type 1 diabetes in autoantibody-positive children. Methods: Prospective cohort studies in Finland, Germany, Sweden and the USA followed 24,662 children at increased genetic or familial risk of developing islet autoimmunity and diabetes. For the 1403 who developed IAbs (523 of whom developed diabetes), levels of autoantibodies against insulin (IAA), glutamic acid decarboxylase (GADA) and insulinoma-associated antigen-2 (IA-2A) were harmonised for analysis. Diabetes prediction models using multivariate logistic regression with inverse probability censored weighting (IPCW) were trained using 10-fold cross-validation. Discriminative power for disease was estimated using the IPCW concordance index (C index) with 95% CI estimated via bootstrap. Results: A baseline model with covariates for data source, sex, diabetes family history, HLA risk group and age at seroconversion with a 10-year follow-up period yielded a C index of 0.61 (95% CI 0.58, 0.63). The performance improved after adding the IAb positivity status for IAA, GADA and IA-2A at seroconversion: C index 0.72 (95% CI 0.71, 0.74). Using the IAb levels instead of positivity indicators resulted in even better performance: C index 0.76 (95% CI 0.74, 0.77). The predictive power was maintained when using the IAb levels alone: C index 0.76 (95% CI 0.75, 0.76). The prediction was better for shorter follow-up periods, with a C index of 0.82 (95% CI 0.81, 0.83) at 2 years, and remained reasonable for longer follow-up periods, with a C index of 0.76 (95% CI 0.75, 0.76) at 11 years. Inclusion of the results of a third IAb test added to the predictive power, and a suitable interval between seroconversion and the third test was approximately 1.5 years, with a C index of 0.78 (95% CI 0.77, 0.78) at 10 years follow-up. Conclusions/interpretation: Consideration of quantitative patterns of IAb levels i
- Published
- 2023
34. Dietary fatty acid intake in childhood and the risk of islet autoimmunity and type 1 diabetes:the DIPP birth cohort study
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Hakola, L. (Leena), Vuorinen, A.-L. (Anna-Leena), Hanna‑Mari, H. (Hanna‑Mari), Niinistö, S. (Sari), Ahonen, S. (Suvi), Rautanen, J. (Jenna), Peltonen, E. J. (Essi J.), Nevalainen, J. (Jaakko), Ilonen, J. (Jorma), Toppari, J. (Jorma), Veijola, R. (Riitta), Knip, M. (Mikael), Virtanen, S. M. (Suvi M.), Hakola, L. (Leena), Vuorinen, A.-L. (Anna-Leena), Hanna‑Mari, H. (Hanna‑Mari), Niinistö, S. (Sari), Ahonen, S. (Suvi), Rautanen, J. (Jenna), Peltonen, E. J. (Essi J.), Nevalainen, J. (Jaakko), Ilonen, J. (Jorma), Toppari, J. (Jorma), Veijola, R. (Riitta), Knip, M. (Mikael), and Virtanen, S. M. (Suvi M.)
- Abstract
Purpose: The aim was to study the associations between dietary intake of fatty acids in childhood and the risk of islet autoimmunity and type 1 diabetes (T1D). Methods: The prospective Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Study included children with genetic susceptibility to T1D born between 1996 and 2004. Participants were followed up every 3 to 12 months up to 6 years for diet, islet autoantibodies, and T1D. Dietary intake of several fatty acids at the age of 3 months to 6 years was assessed 1–8 times per participant with a 3-day food record. Joint models adjusted for energy intake, sex, HLA genotype and familial diabetes were used to investigate the associations of longitudinal intake of fatty acids and the development of islet autoimmunity and T1D. Results: During the 6-year follow-up, 247 (4.4%) children of 5626 developed islet autoimmunity and 94 (1.7%) children of 5674 developed T1D. Higher intake of monounsaturated fatty acids (HR 0.63; 95% CI 0.47, 0.82), arachidonic acid (0.69; 0.50, 0.94), total n-3 fatty acids (0.64; 0.48, 0.84), and long-chain n-3 fatty acids (0.14; 0.04, 0.43), was associated with a decreased risk of islet autoimmunity with and without energy adjustment. Higher intake of total fat (0.73; 0.53, 0.98), and saturated fatty acids (0.55; 0.33, 0.90) was associated with a decreased risk of T1D only when energy adjusted. Conclusion: Intake of several fatty acids was associated with a decreased risk of islet autoimmunity or T1D among high-risk children. Our findings support the idea that dietary factors, including n-3 fatty acids, may play a role in the disease process of T1D.
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- 2023
35. Intake and sources of dietary fibre and dietary fibre fractions in Finnish children
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Salo, T. E. (Tuuli E. I.), Niinistö, S. (Sari), Korhonen, T. E. (Tuuli E.), Pastell, H. (Helena), Reinivuo, H. (Heli), Takkinen, H.-M. (Hanna-Mari), Ilonen, J. (Jorma), Toppari, J. (Jorma), Knip, M. (Mikael), Veijola, R. (Riitta), Virtanen, S. M. (Suvi M.), Salo, T. E. (Tuuli E. I.), Niinistö, S. (Sari), Korhonen, T. E. (Tuuli E.), Pastell, H. (Helena), Reinivuo, H. (Heli), Takkinen, H.-M. (Hanna-Mari), Ilonen, J. (Jorma), Toppari, J. (Jorma), Knip, M. (Mikael), Veijola, R. (Riitta), and Virtanen, S. M. (Suvi M.)
- Abstract
The current definition of dietary fibre was adopted by the Codex Alimentarius Commission in 2009, but implementation requires updating food composition databases with values based on appropriate analysis methods. Previous data on population intakes of dietary fibre fractions are sparse. We studied the intake and sources of total dietary fibre (TDF) and dietary fibre fractions insoluble dietary fibre (IDF), dietary fibre soluble in water but insoluble in 76 % aqueous ethanol (SDFP) and dietary fibre soluble in water and soluble in 76 % aqueous ethanol (SDFS) in Finnish children based on new CODEX-compliant values of the Finnish National Food Composition Database Fineli. Our sample included 5193 children at increased genetic risk of type 1 diabetes from the Type 1 Diabetes Prediction and Prevention birth cohort, born between 1996 and 2004. We assessed the intake and sources based on 3-day food records collected at the ages of 6 months, 1, 3 and 6 years. Both absolute and energy-adjusted intakes of TDF were associated with age, sex and breast-feeding status of the child. Children of older parents, parents with a higher level of education, non-smoking mothers and children with no older siblings had higher energy-adjusted TDF intake. IDF was the major dietary fibre fraction in non-breastfed children, followed by SDFP and SDFS. Cereal products, fruits and berries, potatoes and vegetables were major food sources of dietary fibre. Breast milk was a major source of dietary fibre in 6-month-olds due to its human milk oligosaccharide content and resulted in high SDFS intakes in breastfed children.
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- 2023
36. What is the role of puberty in the development of islet autoimmunity and progression to type 1 diabetes?
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Peltonen, E. J. (Essi J.), Veijola, R. (Riitta), Ilonen, J. (Jorma), Knip, M. (Mikael), Niinikoski, H. (Harri), Toppari, J. (Jorma), Virtanen, H. E. (Helena E.), Virtanen, S. M. (Suvi M.), Peltonen, J. (Jaakko), Nevalainen, J. (Jaakko), Peltonen, E. J. (Essi J.), Veijola, R. (Riitta), Ilonen, J. (Jorma), Knip, M. (Mikael), Niinikoski, H. (Harri), Toppari, J. (Jorma), Virtanen, H. E. (Helena E.), Virtanen, S. M. (Suvi M.), Peltonen, J. (Jaakko), and Nevalainen, J. (Jaakko)
- Abstract
In many populations, the peak period of incidence of type 1 diabetes (T1D) has been observed to be around 10–14 years of age, coinciding with puberty, but direct evidence of the role of puberty in the development of T1D is limited. We therefore aimed to investigate whether puberty and the timing of its onset are associated with the development of islet autoimmunity (IA) and subsequent progression to T1D. A Finnish population-based cohort of children with HLA-DQB1-conferred susceptibility to T1D was followed from 7 years of age until 15 years of age or until a diagnosis of T1D (n = 6920). T1D-associated autoantibodies and growth were measured at 3- to 12-month intervals, and pubertal onset timing was assessed based on growth. The analyses used a three-state survival model. IA was defined as being either positive for islet cell antibodies plus at least one biochemical autoantibody (ICA + 1) or as being repeatedly positive for at least one biochemical autoantibody (BC1). Depending on the IA definition, either 303 (4.4%, ICA + 1) or 435 (6.3%, BC1) children tested positive for IA by the age of 7 years, and 211 (3.2%, ICA + 1)) or 198 (5.3%, BC1) developed IA during follow-up. A total of 172 (2.5%) individuals developed T1D during follow-up, of whom 169 were positive for IA prior to the clinical diagnosis. Puberty was associated with an increase in the risk of progression to T1D, but only from ICA + 1-defined IA (hazard ratio 1.57; 95% confidence interval 1.14, 2.16), and the timing of pubertal onset did not affect the association. No association between puberty and the risk of IA was detected. In conclusion, puberty may affect the risk of progression but is not a risk factor for IA.
- Published
- 2023
37. DNA methylation differences within INS, PTPN22 and IL2RA promoters in lymphocyte subsets in children with type 1 diabetes and controls
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Pahkuri, S. (Sirpa), Ekman, I. (Ilse), Vandamme, C. (Céline), Näntö-Salonen, K. (Kirsti), Toppari, J. (Jorma), Veijola, R. (Riitta), Knip, M. (Mikael), Kinnunen, T. (Tuure), Ilonen, J. (Jorma), Lempainen, J. (Johanna), Pahkuri, S. (Sirpa), Ekman, I. (Ilse), Vandamme, C. (Céline), Näntö-Salonen, K. (Kirsti), Toppari, J. (Jorma), Veijola, R. (Riitta), Knip, M. (Mikael), Kinnunen, T. (Tuure), Ilonen, J. (Jorma), and Lempainen, J. (Johanna)
- Abstract
We elucidated the effect of four known T1D-susceptibility associated single nucleotide polymorphism (SNP) markers in three genes (rs12722495 and rs2104286 in IL2RA, rs689 in INS and rs2476601 in PTPN22) on CpG site methylation of their proximal promoters in different lymphocyte subsets using pyrosequencing. The study cohort comprised 25 children with newly diagnosed T1D and 25 matched healthy controls. The rs689 SNP was associated with methylation at four CpG sites in INS promoter: −234, −206, −102 and −69. At all four CpG sites, the susceptibility genotype AA was associated with a higher methylation level compared to the other genotypes. We also found an association between rs12722495 and methylation at CpG sites −373 and −356 in IL2RA promoter in B cells, where the risk genotype AA was associated with lower methylation level compared to the AG genotype. The other SNPs analyzed did not demonstrate significant associations with CpG site methylation in the examined genes. Additionally, we compared the methylation between children with T1D and controls, and found statistically significant methylation differences at CpG −135 in INS in CD8+ T cells (p = 0.034), where T1D patients had a slightly higher methylation compared to controls (87.3 ± 7.2 vs. 78.8 ± 8.9). At the other CpG sites analyzed, the methylation was similar. Our results not only confirm the association between INS methylation and rs689 discovered in earlier studies but also report this association in sorted immune cells. We also report an association between rs12722495 and IL2RA promoter methylation in B cells. These results suggest that at least part of the genetic effect of rs689 and rs12722495 on T1D pathogenesis may be conveyed by DNA methylation.
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- 2023
38. Circulating metabolic signatures of rapid and slow progression to type 1 diabetes in islet autoantibody-positive children
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Lamichhane, S. (Santosh), Sen, P. (Partho), Dickens, A. M. (Alex M.), Kråkström, M. (Matilda), Ilonen, J. (Jorma), Lempainen, J. (Johanna), Hyöty, H. (Heikki), Lahesmaa, R. (Riitta), Veijola, R. (Riitta), Toppari, J. (Jorma), Hyötyläinen, T. (Tuulia), Knip, M. (Mikael), Orešič, M. (Matej), Lamichhane, S. (Santosh), Sen, P. (Partho), Dickens, A. M. (Alex M.), Kråkström, M. (Matilda), Ilonen, J. (Jorma), Lempainen, J. (Johanna), Hyöty, H. (Heikki), Lahesmaa, R. (Riitta), Veijola, R. (Riitta), Toppari, J. (Jorma), Hyötyläinen, T. (Tuulia), Knip, M. (Mikael), and Orešič, M. (Matej)
- Abstract
Aims/hypothesis: Appearance of multiple islet cell autoantibodies in early life is indicative of future progression to overt type 1 diabetes, however, at varying rates. Here, we aimed to study whether distinct metabolic patterns could be identified in rapid progressors (RP, disease manifestation within 18 months after the initial seroconversion to autoantibody positivity) vs. slow progressors (SP, disease manifestation at 60 months or later from the appearance of the first autoantibody). Methods: Longitudinal samples were collected from RP (n=25) and SP (n=41) groups at the ages of 3, 6, 12, 18, 24, or ≥ 36 months. We performed a comprehensive metabolomics study, analyzing both polar metabolites and lipids. The sample series included a total of 239 samples for lipidomics and 213 for polar metabolites. Results: We observed that metabolites mediated by gut microbiome, such as those involved in tryptophan metabolism, were the main discriminators between RP and SP. The study identified specific circulating molecules and pathways, including amino acid (threonine), sugar derivatives (hexose), and quinic acid that may define rapid vs. slow progression to type 1 diabetes. However, the circulating lipidome did not appear to play a major role in differentiating between RP and SP. Conclusion/interpretation: Our study suggests that a distinct metabolic profile is linked with the type 1 diabetes progression. The identification of specific metabolites and pathways that differentiate RP from SP may have implications for early intervention strategies to delay the development of type 1 diabetes.
- Published
- 2023
39. Serum APOC1 levels are decreased in young autoantibody positive children who rapidly progress to type 1 diabetes
- Author
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Hirvonen, M. K. (M. Karoliina), Lietzén, N. (Niina), Moulder, R. (Robert), Bhosale, S. D. (Santosh D.), Koskenniemi, J. (Jaakko), Vähä-Mäkilä, M. (Mari), Nurmio, M. (Mirja), Orešič, M. (Matej), Ilonen, J. (Jorma), Toppari, J. (Jorma), Veijola, R. (Riitta), Hyöty, H. (Heikki), Lähdesmäki, H. (Harri), Knip, M. (Mikael), Cheng, L. (Lu), Lahesmaa, R. (Riitta), Hirvonen, M. K. (M. Karoliina), Lietzén, N. (Niina), Moulder, R. (Robert), Bhosale, S. D. (Santosh D.), Koskenniemi, J. (Jaakko), Vähä-Mäkilä, M. (Mari), Nurmio, M. (Mirja), Orešič, M. (Matej), Ilonen, J. (Jorma), Toppari, J. (Jorma), Veijola, R. (Riitta), Hyöty, H. (Heikki), Lähdesmäki, H. (Harri), Knip, M. (Mikael), Cheng, L. (Lu), and Lahesmaa, R. (Riitta)
- Abstract
Better understanding of the early events in the development of type 1 diabetes is needed to improve prediction and monitoring of the disease progression during the substantially heterogeneous presymptomatic period of the beta cell damaging process. To address this concern, we used mass spectrometry-based proteomics to analyse longitudinal pre-onset plasma sample series from children positive for multiple islet autoantibodies who had rapidly progressed to type 1 diabetes before 4 years of age (n = 10) and compared these with similar measurements from matched children who were either positive for a single autoantibody (n = 10) or autoantibody negative (n = 10). Following statistical analysis of the longitudinal data, targeted serum proteomics was used to verify 11 proteins putatively associated with the disease development in a similar yet independent and larger cohort of children who progressed to the disease within 5 years of age (n = 31) and matched autoantibody negative children (n = 31). These data reiterated extensive age-related trends for protein levels in young children. Further, these analyses demonstrated that the serum levels of two peptides unique for apolipoprotein C1 (APOC1) were decreased after the appearance of the first islet autoantibody and remained relatively less abundant in children who progressed to type 1 diabetes, in comparison to autoantibody negative children.
- Published
- 2023
40. Large-Scale Formation of DNA Origami Lattices on Silicon
- Author
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(0000-0001-6932-9742) Tapio, K., (0000-0002-3002-6098) Kielar, C., (0000-0003-0897-1461) Parikka, J. M., (0000-0001-7139-3110) Keller, A., (0009-0000-8672-3645) Järvinen, H., (0000-0002-8752-5824) Fahmy, K., (0000-0002-1698-5591) Jussi Toppari, J., (0000-0001-6932-9742) Tapio, K., (0000-0002-3002-6098) Kielar, C., (0000-0003-0897-1461) Parikka, J. M., (0000-0001-7139-3110) Keller, A., (0009-0000-8672-3645) Järvinen, H., (0000-0002-8752-5824) Fahmy, K., and (0000-0002-1698-5591) Jussi Toppari, J.
- Abstract
In recent years, hierarchical nanostructures have found applications in fields like diagnostics, medicine, nano-optics, and nanoelectronics, especially in challenging applications like the creation of metasurfaces with unique optical properties. One of the promising materials to fabricate such nanostructures has been DNA due to its robust self-assembly properties and plethora of different functionalization schemes. Here, we demonstrate the assembly of a two-dimensional fishnet-type lattice on a silicon substrate using cross-shaped DNA origami as the building block, i.e., tile. The effects of different environmental and structural factors are investigated under liquid atomic force microscopy (AFM) to optimize the lattice assembly. Furthermore, the arm-to-arm binding affinity of the tiles is analyzed, revealing preferential orientations. From the liquid AFM results, we develop a methodology to produce closely-spaced DNA origami lattices on silicon substrate, which allows further nanofabrication process steps, such as metallization. This formed polycrystalline lattice has high surface coverage and is extendable to the wafer scale with an average domain size of about a micrometer. Further studies are needed to increase the domain size toward a single-crystalline large-scale lattice.
- Published
- 2023
41. SERS detection of cell surface and intracellular components of microorganisms using nano-aggregated Ag substrate
- Author
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Lemma, Tibebe, Saliniemi, Alex, Hynninen, Ville, Hytönen, Vesa P., and Toppari, J. Jussi
- Published
- 2016
- Full Text
- View/download PDF
42. DNA-Assisted Molecular Lithography
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Shen, Boxuan, primary, Linko, Veikko, additional, and Toppari, J. Jussi, additional
- Published
- 2018
- Full Text
- View/download PDF
43. Large-Scale Formation of DNA Origami Lattices on Silicon
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Tapio, Kosti, primary, Kielar, Charlotte, additional, Parikka, Johannes M., additional, Keller, Adrian, additional, Järvinen, Heini, additional, Fahmy, Karim, additional, and Toppari, J. Jussi, additional
- Published
- 2023
- Full Text
- View/download PDF
44. Elongation and plasmonic activity of embedded metal nanoparticles following heavy ion irradiation
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Korkos, Spyridon, primary, Arstila, Kai, additional, Tapio, Kosti, additional, Kinnunen, Sami, additional, Toppari, J. Jussi, additional, and Sajavaara, Timo, additional
- Published
- 2023
- Full Text
- View/download PDF
45. Creation of ordered 3D tubes out of DNA origami lattices
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Parikka, Johannes M., primary, Järvinen, Heini, additional, Sokołowska, Karolina, additional, Ruokolainen, Visa, additional, Markešević, Nemanja, additional, Natarajan, Ashwin K., additional, Vihinen-Ranta, Maija, additional, Kuzyk, Anton, additional, Tapio, Kosti, additional, and Toppari, J. Jussi, additional
- Published
- 2023
- Full Text
- View/download PDF
46. Measuring optical anisotropy in poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) films with added graphene
- Author
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Isoniemi, Tommi, Tuukkanen, Sampo, Cameron, David C., Simonen, Janne, and Toppari, J. Jussi
- Published
- 2015
- Full Text
- View/download PDF
47. Effect of molecular Stokes shift on polariton dynamics.
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Hulkko, E., Pikker, S., Tiainen, V., Tichauer, R. H., Groenhof, G., and Toppari, J. J.
- Subjects
STOKES shift ,POLARITONS ,FORCE & energy ,MOLECULAR dynamics ,ELECTROMAGNETIC fields ,BAND gaps - Abstract
When the enhanced electromagnetic field of a confined light mode interacts with photoactive molecules, the system can be driven into the regime of strong coupling, where new hybrid light–matter states, polaritons, are formed. Polaritons, manifested by the Rabi split in the dispersion, have shown potential for controlling the chemistry of the coupled molecules. Here, we show by angle-resolved steady-state experiments accompanied by multi-scale molecular dynamics simulations that the molecular Stokes shift plays a significant role in the relaxation of polaritons formed by organic molecules embedded in a polymer matrix within metallic Fabry–Pérot cavities. Our results suggest that in the case of Rhodamine 6G, a dye with a significant Stokes shift, excitation of the upper polariton leads to a rapid localization of the energy into the fluorescing state of one of the molecules, from where the energy scatters into the lower polariton (radiative pumping), which then emits. In contrast, for excitonic J-aggregates with a negligible Stokes shift, the fluorescing state does not provide an efficient relaxation gateway. Instead, the relaxation is mediated by exchanging energy quanta matching the energy gap between the dark states and lower polariton into vibrational modes (vibrationally assisted scattering). To understand better how the fluorescing state of a molecule that is not strongly coupled to the cavity can transfer its excitation energy to the lower polariton in the radiative pumping mechanism, we performed multi-scale molecular dynamics simulations. The results of these simulations suggest that non-adiabatic couplings between uncoupled molecules and the polaritons are the driving force for this energy transfer process. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
48. Polariton response in the presence of Brownian dissipation from molecular vibrations.
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Kansanen, Kalle S. U., Toppari, J. Jussi, and Heikkilä, Tero T.
- Subjects
- *
MOLECULAR vibration , *CHEMICAL kinetics , *FREQUENCIES of oscillating systems , *POLARITONS , *STOKES shift , *NONLINEAR oscillators , *CONDITIONED response - Abstract
We study the elastic response of a stationarily driven system of a cavity field strongly coupled with molecular excitons, taking into account the main dissipation channels due to the finite cavity linewidth and molecular vibrations. We show that the frequently used coupled oscillator model fails in describing this response especially due to the non-Lorentzian dissipation of the molecules to their vibrations. Signatures of this failure are the temperature dependent minimum point of the polariton peak splitting, the uneven polariton peak height at the minimum splitting, and the asymmetric shape of the polariton peaks even at the experimentally accessed "zero-detuning" point. Using a rather generic yet representative model of molecular vibrations, we predict the polariton response in various conditions, depending on the temperature, molecular Stokes shift and vibration frequencies, and the size of the Rabi splitting. Our results can be used as a sanity check of the experiments trying to "prove" results originating from strong coupling, such as vacuum-enhanced chemical reaction rate. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
49. Serum testosterone levels in 3-month-old boys predict their semen quality as young adults
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L Scheutz Henriksen, J Holm Petersen, Skakkebaek NE, Jorgensen N, Virtanen HE, Priskorn L, Juul A, Toppari J, and Main KM
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General Economics, Econometrics and Finance - Published
- 2022
50. Goodbye International Journal of Andrology , welcome Andrology !
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Rajpert‐De Meyts, E., primary, Eliasson, R., additional, Comhaire, F. H., additional, Skakkebæk, N. E., additional, Sharpe, R. M., additional, and Toppari, J., additional
- Published
- 2022
- Full Text
- View/download PDF
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