1. |
- Adloff, C, et al.
(författare)
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Energy flow and rapidity gaps between jets in photoproduction at HERA
- 2002
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 24:4, s. 517-527
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Tidskriftsartikel (refereegranskat)abstract
- Dijet events in photon-proton collisions in which there is a large pseudorapidity separation, Deltaeta > 2.5 between the two highest E-T jets are studied with the H1 detector at HERA. The inclusive dijet cross sections are measured as functions of the longitudinal momentum fractions of the proton and photon which participate in the production of the jets, x(p)(jets) and x(gamma)(jets) respectively, Deltaeta, the pseudorapidity P separation between the two highest E-T jets, and E-T(gap), the total summed transverse energy between the jets. Rapidity gap events are defined as events in which E-T(gap) is less than E-T(cut), for E-T(cut) varied between jets 0.5 and 2.0 GeV. The fraction of dijet events with a rapidity gap is measured differentially in Deltaeta, x(p)(jets) and x(gamma)(jets). An excess of events with rapidity gaps at low values of E-T(cut) is observed above the expectation from standard photoproduction processes. This excess can be explained by the exchange of a strongly interacting colour singlet object between the jets.
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2. |
- Aidas, Kestutis, et al.
(författare)
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The Dalton quantum chemistry program system
- 2014
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Ingår i: WIREs Computational Molecular Science. - : Wiley. - 1759-0876 .- 1759-0884. ; 4:3, s. 269-284
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Tidskriftsartikel (refereegranskat)abstract
- Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, MOller-Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantum-mechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from for a number of UNIX platforms.
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3. |
- Brooke, Robert, et al.
(författare)
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Infrared electrochromic conducting polymer devices
- 2017
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Ingår i: Journal of Materials Chemistry C. - : The Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 5:23, s. 5824-5830
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Tidskriftsartikel (refereegranskat)abstract
- The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is well known for its electrochromic properties in the visible region. Less focus has been devoted to the infrared (IR) wavelength range, although tunable IR properties could enable a wide range of novel applications. As an example, modern day vehicles have thermal cameras to identify pedestrians and animals in total darkness, but road and speed signs cannot be easily visualized by these imaging systems. IR electrochromism could enable a new generation of dynamic road signs that are compatible with thermal imaging, while simultaneously providing contrast also in the visible region. Here, we present the first metal-free flexible IR electrochromic devices, based on PEDOT:Tosylate as both the electrochromic material and electrodes. Lateral electrochromic devices enabled a detailed investigation of the IR electrochromism of thin PEDOT:Tosylate films, revealing large changes in their thermal signature, with effective temperature changes up to 10 [degree]C between the oxidized (1.5 V) and reduced (-1.5 V) states of the polymer. Larger scale (7 [times] 7 cm) vertical electrochromic devices demonstrate practical suitability and showed effective temperature changes of approximately 7 [degree]C, with good optical memory and fast switching (1.9 s from the oxidized state to the reduced state and 3.3 s for the reversed switching). The results are highly encouraging for using PEDOT:Tosylate for IR electrochromic applications.
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4. |
- Brooke, Robert, 1989-, et al.
(författare)
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Infrared electrochromic conducting polymer devices
- 2017
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 5:23, s. 5824-5830
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Tidskriftsartikel (refereegranskat)abstract
- The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is well known for its electrochromic properties in the visible region. Less focus has been devoted to the infrared (IR) wavelength range, although tunable IR properties could enable a wide range of novel applications. As an example, modern day vehicles have thermal cameras to identify pedestrians and animals in total darkness, but road and speed signs cannot be easily visualized by these imaging systems. IR electrochromism could enable a new generation of dynamic road signs that are compatible with thermal imaging, while simultaneously providing contrast also in the visible region. Here, we present the first metal-free flexible IR electrochromic devices, based on PEDOT:Tosylate as both the electrochromic material and electrodes. Lateral electrochromic devices enabled a detailed investigation of the IR electrochromism of thin PEDOT:Tosylate films, revealing large changes in their thermal signature, with effective temperature changes up to 10 °C between the oxidized (1.5 V) and reduced (-1.5 V) states of the polymer. Larger scale (7 × 7 cm) vertical electrochromic devices demonstrate practical suitability and showed effective temperature changes of approximately 7 °C, with good optical memory and fast switching (1.9 s from the oxidized state to the reduced state and 3.3 s for the reversed switching). The results are highly encouraging for using PEDOT:Tosylate for IR electrochromic applications.
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5. |
- Che, Canyan, 1988-, et al.
(författare)
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Twinning Lignosulfonate with a Conducting Polymer via Counter-Ion Exchange for Large-Scale Electrical Storage
- 2019
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Ingår i: Advanced Sustainable Systems. - : Wiley-VCH Verlag. - 2366-7486. ; 3:9
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Tidskriftsartikel (refereegranskat)abstract
- Lignosulfonate (LS) is a large-scale surplus product of the forest and paper industries, and has primarily been utilized as a low-cost plasticizer in making concrete for the construction industry. LS is an anionic redox-active polyelectrolyte and is a promising candidate to boost the charge capacity of the positive electrode (positrode) in redox-supercapacitors. Here, the physical-chemical investigation of how this biopolymer incorporates into the conducting polymer PEDOT matrix, of the positrode, by means of counter-ion exchange is reported. Upon successful incorporation, an optimal access to redox moieties is achieved, which provides a 63% increase of the resulting stored electrical charge by reversible redox interconversion. The effects of pH, ionic strength, and concentrations, of included components, on the polymer–polymer interactions are optimized to exploit the biopolymer-associated redox currents. Further, the explored LS-conducting polymer incorporation strategy, via aqueous synthesis, is evaluated in an up-scaling effort toward large-scale electrical energy storage technology. By using an up-scaled production protocol, integration of the biopolymer within the conducting polymer matrix by counter-ion exchange is confirmed and the PEDOT-LS synthesized through optimized strategy reaches an improved charge capacity of 44.6 mAh g−1.
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6. |
- Gisladottir, Rosa S, et al.
(författare)
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Sequence Variants in TAAR5 and Other Loci Affect Human Odor Perception and Naming.
- 2020
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Ingår i: Current biology : CB. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 30:23
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Tidskriftsartikel (refereegranskat)abstract
- Olfactory receptor (OR) genes in humans form a special class characterized by unusually high DNA sequence diversity, which should give rise to differences in perception and behavior. In the largest genome-wide association study to date based on olfactory testing, we investigated odor perception and naming with smell tasks performed by 9,122 Icelanders, with replication in a separate sample of 2,204 individuals. We discovered an association between a low-frequency missense variant in TAAR5 and reduced intensity rating of fish odor containing trimethylamine (p.Ser95Pro, pcombined= 5.6× 10-15). We demonstrate that TAAR5 genotype affects aversion to fish odor, reflected by linguistic descriptions of the odor and pleasantness ratings. We also discovered common sequence variants in two canonical olfactory receptor loci that associate with increased intensity and naming of licorice odor (trans-anethole: lead variant p.Lys233Asn in OR6C70, pcombined= 8.8× 10-16 and pcombined= 1.4× 10-9) and enhanced naming of cinnamon (trans-cinnamaldehyde; intergenic variant rs317787-T, pcombined= 5.0× 10-17). Together, our results show that TAAR5 genotype variation influences human odor responses and highlight that sequence diversity in canonical OR genes can lead to enhanced olfactory ability, in contrast to the view that greater tolerance for mutations in the human OR repertoire leads to diminished function.
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7. |
- Håkansson, H., et al.
(författare)
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In vivo and in vitro toxicity of fractionated fish lipids, with particular regard to their content of chlorinated organic compounds
- 1991
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Ingår i: Pharmacology and Toxicology. - : Wiley. - 0901-9928 .- 1600-0773. ; 69:6, s. 459-471
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Tidskriftsartikel (refereegranskat)abstract
- Six different lipid matrices (the intact lipid (IL), four lipid fractions with different polarity, and the free fatty acids (FFAs) obtained by hydrolysis of the triacylglycerol (TAG) containing fraction) were obtained from salmon (Salmo salar) and eel (Anguilla anguilla), each collected at a contaminated and a comparatively uncontaminated catch site along the coast of Scandinavia. The lipid matrices were studied in toxicological test systems representing various biological functions of different organ systems from several species and trophic levels. The results were evaluated with particular respect to the concentrations of extractable organically bound chlorine (EOCl) in the matrices tested. In some test systems, the specimens with a higher EOCl concentration appeared to be more toxic. For example, the TAG containing fraction (F2) from Idefjord eel, having a higher EOCl content than F2 from Oslofjord eel, reduced the number and hatchability of eggs laid by zebrafish. Both IL and F2 of Idefjord eel increased mortality and reduced the oxygen/nitrogen-ratio in blue mussels. Non-polar compounds (F1) from Bothnian Sea salmon induced 7-ethoxyresurofin O-deethylase (EROD) activity in rainbow trout hepatocytes, whereas F1 from Senja salmon did not. F1 from Bothnian Sea salmon also reduced the number of T-cells in foetal mouse thymus anlagen in vitro compared with the cell number in anlagen exposed to F1 from Senja salmon. A positive correlation between EOCl concentration and test response was found for EROD activity in rainbow trout hepatocytes and for ATP-leakage in Erlich ascites tumour cells when testing the phospolipid containing fraction (F4). However, in most test systems the fish oils, irrespective of EOCl content, were of low toxicity, and the observed effects need to be verified in future studies.
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8. |
- Jonsson, Magnus P., et al.
(författare)
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Simultaneous Nanoplasmonic and Quartz Crystal Microbalance Sensing: Analysis of Biomolecular Conformational Changes and Quantification of the Bound Molecular Mass
- 2008
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Ingår i: Analytical Chemistry. - : American Chemical Society. - 0003-2700 .- 1520-6882. ; 80:21, s. 7988-7995
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a study of supported lipid bilayer (SIB) formation and subsequent protein binding using a sensor that combines localized surface plasmon resonance (LSPR) and quartz crystal microbalance with dissipation (QCM-D) monitoring. The LSPR activity arises from silicon oxide (SiOx) coated nanometric apertures in a thin gold film, which also serves as the active electrode of a QCM-D crystal. Both transducer principles provide signatures for the formation of a SLB upon adsorption and subsequent rupture of adsorbed lipid vesicles. However, the two techniques are sensitive over different regions of the sample: LSPR primarily inside and on the rim of the holes and QCM-D primarily on the planar areas between the holes. Although the dimension of the lipid vesicles is on the same order as the dimension of the nanoholes, it is concluded from the response of the combined system that vesicle rupture in the nanoholes and on the planar region between the holes is synchronized. Furthermore, by determining the thickness of the SLB from the QCM-D response, the characteristic decay length of the LSPR field intensity could be determined. This made it possible not only to determine the mass and refractive index of the homogeneous SLB but also to postulate a generic means to quantify the LSPR response in terms of mass-uptake also for nonhomogeneous films. This is exemplified by measuring the adsorbed lipid mass during vesicle adsorption, yielding the critical lipid vesicle coverage at which spontaneous rupture into a planar bilayer occurs. The generic applicability and versatility of the method is demonstrated from specific protein binding to a functionalized SLB. From the absolute refractive index of the protein, provided from the LSPR data alone, it was possible to determine both the effective thickness of the protein film and the molecular mass (or number) of bound protein.
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9. |
- Kristiansson, M., et al.
(författare)
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Drones can be used to provide dispatch centres with on-site photos before arrival of EMS in time critical incidents
- 2024
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Ingår i: Resuscitation. - 0300-9572 .- 1873-1570. ; , s. 110312-110312
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundDrones are able to deliver automated external defibrillators in cases of out-of-hospital cardiac arrest (OHCA) but can be deployed for other purposes. Our aim was to evaluate the feasibility of sending live photos to dispatch centres before arrival of other units during time-critical incidents.MethodsIn this retrospective observational study, the regional dispatch centre implemented a new service using five existing AED-drone systems covering an estimated 200 000 inhabitants in Sweden. Drones were deployed automatically over a 4-month study period (December 2022–April 2023) in emergency calls involving suspected OHCAs, traffic accidents and fires in buildings. Upon arrival at the scene, an overhead photo was taken and transmitted to the dispatch centre. Feasibility of providing photos in real time, and time delays intervals were examined.ResultsOverall, drones were deployed in 59/440 (13%) of all emergency calls: 26/59 (44%) of suspected OHCAs, 20/59 (34%) of traffic accidents, and 13/59 (22%) of fires in buildings.The main reasons for non-deployment were closed airspace and unfavourable weather conditions (68%). Drones arrived safely at the exact location in 58/59 cases (98%). Their overall median response time was 3:49 min, (IQR 3:18–4:26) vs. emergency medical services (EMS), 05:51 (IQR: 04:29–08:04) p-value for time difference between drone and EMS = 0,05. Drones arrived first on scene in 47/52 cases (90%) and the largest median time difference was found in suspected OHCAs 4:10 min, (IQR: 02:57–05:28). The time difference in the 5/52 (10%) cases when EMS arrived first the time difference was 5:18 min (IQR 2:19–7:38), p = NA. Photos were transmitted correctly in all 59 alerts. No adverse events occurred.ConclusionIn a newly implemented drone dispatch service, drones were dispatched to 13% of relevant EMS calls. When drones were dispatched, they arrived at scene earlier than EMS services in 90% of cases. Drones were able to relay photos to the dispatch centre in all cases.Although severely affected by closed airspace and weather conditions, this novel method may facilitate additional decision-making information during time-critical incidents.
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10. |
- Sandberg, Mats, et al.
(författare)
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Photoconductive zinc oxide-composite paper by pilot paper machine manufacturing
- 2016
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Ingår i: Flexible and Printed Electronics. - : IOP Publishing. - 2058-8585. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- Smartmaterials can be used for awide variety of applications, including sensing and energy harvesting.Implementation of smartmaterials in large area devices requires scalablemanufacturing. The use ofpaper-making techniques would offer an enormous production capacity, allowing for low-cost andlarge-scalemanufacturing. In thisworkwe present a successful pilot scale papermachinemanufacturingof functional composite papers(100mmin−1 with aweb width of 30 cm) based on cellulose fibres andcommercial tetrapodal zinc oxidemicrowhiskers(ZnO-Ts).Carbon electrodes could successfully beprinted on the paper to form complete electronic devices where the paper itself is the active material.Thisenabled development of aZnO-composite paper photosensor,where we characterized its stability,sensitivity and speed. The devices show excellent photosensing properties over awide range of lightirradiances(0.01–1Sun), including short response times (∼10 s) and long-term stability. Under simulatedsunlight and a bias voltage of 1 V, small(0.5 cm2) two-probe interdigitated photosensor devices provided12μAphotocurrent.Under the same conditions, four-probe measurements of the composite papershowed a sheet resistance of 6.9·107Ω/sq. Four-probe measurements also demonstrated that the paperconductivity varies linearlywith light irradiance. To the best of ourknowledge, this is thefirst example ofpilot paper machine production of an optoelectronic paper, demonstrating the potential for large-scalepapermanufacturing of active smart paper from low-cost industrial bulk materials.
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11. |
- Stavrinidou, Eleni, et al.
(författare)
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In vivo polymerization and manufacturing of wires and supercapacitors in plants
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 114:11, s. 2807-2812
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Tidskriftsartikel (refereegranskat)abstract
- Electronic plants, e-Plants, are an organic bioelectronic platform that allows electronic interfacing with plants. Recently we have demonstrated plants with augmented electronic functionality. Using the vascular system and organs of a plant, we manufactured organic electronic devices and circuits in vivo, leveraging the internal structure and physiology of the plant as the template, and an integral part of the devices. However, this electronic functionality was only achieved in localized regions, whereas new electronic materials that could be distributed to every part of the plant would provide versatility in device and circuit fabrication and create possibilities for new device concepts. Here we report the synthesis of such a conjugated oligomer that can be distributed and form longer oligomers and polymer in every part of the xylem vascular tissue of a Rosa floribunda cutting, forming long-range conducting wires. The plant’s structure acts as a physical template, whereas the plant’s biochemical response mechanism acts as the catalyst for polymerization. In addition, the oligomer can cross through the veins and enter the apoplastic space in the leaves. Finally, using the plant’s natural architecture we manufacture supercapacitors along the stem. Our results are preludes to autonomous energy systems integrated within plants and distribute interconnected sensor-actuator systems for plant control and optimization
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12. |
- Xiong, Kunli, 1987, et al.
(författare)
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Switchable Plasmonic Metasurfaces with High Chromaticity Containing only Abundant Metals
- 2017
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 17:11, s. 7033-7039
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Tidskriftsartikel (refereegranskat)abstract
- Plasmonic color generation offers several advantages but is also limited by the cost and availability of noble metals like gold. In this work, we present color-tunable metasurfaces with high chromaticity and reflectivity consisting of an aluminum mirror, a dielectric spacer, and a plasmonic nanohole array in copper. Copper is shown to be an excellent alternative to gold when properly protected from oxidation and makes it possible to generate a wide RGB gamut covering 27% of the standard RGB. By patterning the metasurfaces into microscale pixel triplets, color photos can be well reproduced with high resolution over wafer-sized areas. Further, we demonstrate active modulation of the reflected intensity using an electrochromic conductive polymer deposited on top of the nanostructures by screen printing. This technology opens up for ultrathin and flexible reflective displays in full color, that is, plasmonic electronic paper, compatible with large-scale sustainable production.
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13. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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14. |
- Bergström, Lars Magnus, et al.
(författare)
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A model-independent evaluation of experimental data, and comparison with theory, of synergistic effects in mixtures of an ionic and a nonionic surfactant
- 2003
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 19:26, s. 10719-10725
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Tidskriftsartikel (refereegranskat)abstract
- Critical micelle concentrations for mixtures of an anionic (sodium dodecyl sulfate) and a nonionic (decyl beta-glucoside) surfactant was obtained from surface tension measurements at different concentrations of added NaCl. The observed synergistic effects were analyzed by means of introducing a novel model-independent synergy parameter. The model-independent evaluation has enabled the comparison of experimental results with a theoretical model based on the Poisson-Boltzmann (PB) mean field theory for spherical, cylindrical, and planar geometries, respectively. We found that best agreement with experimental data was obtained for largely curved structures (spherical and cylindrical micelles) at all [NaCl], which is consistent with the fact that rather small micelles, as a rule, form at the critical micelle concentration. Moreover, the PB theory was found to better describe synergistic behavior of the experimental data than the more conventional regular mixture theory, in particular at low electrolyte concentrations. The magnitude of the observed synergistic effects was found to increase as a small amount of NaCl was added and reach a maximum at [NaCl] = 10 mM, in agreement with the PB theory. As expected, synergism was observed to decrease in magnitude upon further addition of NaCl.
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15. |
- Dahlin, Andreas, 1980, et al.
(författare)
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High-Resolution Microspectroscopy of Plasmonic Nanostructures for Miniaturized Biosensing
- 2009
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Ingår i: Analytical Chemistry. - : American Chemical Society. - 0003-2700 .- 1520-6882. ; 81:16, s. 6572-6580
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we demonstrate how to perform microscale spectroscopy of plasmonic nanostructures in order to minimize the noise when determining the resonance peak wavelength. This is accomplished using an experimental setup containing standard optical components mounted on an ordinary light microscope. We present a detailed comparison between extinction spectroscopy in transmission mode and scattering spectroscopy under dark field illumination, which shows that extinction measurements provide higher signal-to-noise in almost all situations. Furthermore, it is shown that rational selection of nanostructure, hardware components, and data analysis algorithms enables tracking of the particle plasmon resonance wavelength from a 10 mu m x 50 mu m area with a resolution of 10(-3) nm in transmission mode. We investigate how the temporal resolution, which can be improved down to 17 Ins, affects, the noise characteristics. In addition, we show how data can be acquired from an area as small as 2 mu m x 10 mu m (similar to 240 particles) at the expense of higher noise on longer time scales. In comparison with previous work on macroscopic sensor designs, this represents a sensor miniaturization of 5 orders of magnitude, without any loss in signal-to-noise performance. As a model system, we illustrate biomolecular detection using gold nanodisks prepared by colloidal lithography. The microextinction measurements of nanodisks described here provide detection of protein surface coverages as low as 40 pg/cm(2) (less than0.1% of saturated binding). In fact, the miniaturized system provides a detection limit in terms of surface coverage comparable to state of the art macroscopic sensors, while simultaneously being as close to single protein molecule detection as sensors based on a single nanoparticle.
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16. |
- Forsberg, Karin, et al.
(författare)
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Novel antibodies reveal inclusions containing non-native SOD1 in sporadic ALS patients
- 2010
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Ingår i: PLOS ONE. - : Public library of science. - 1932-6203. ; 5:7, s. e11552-
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Tidskriftsartikel (refereegranskat)abstract
- Mutations in CuZn-superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS) and are found in 6% of ALS patients. Non-native and aggregation-prone forms of mutant SOD1s are thought to trigger the disease. Two sets of novel antibodies, raised in rabbits and chicken, against peptides spaced along the human SOD1 sequence, were by enzyme-linked immunosorbent assay and an immunocapture method shown to be specific for denatured SOD1. These were used to examine SOD1 in spinal cords of ALS patients lacking mutations in the enzyme. Small granular SOD1-immunoreactive inclusions were found in spinal motoneurons of all 37 sporadic and familial ALS patients studied, but only sparsely in 3 of 28 neurodegenerative and 2 of 19 non-neurological control patients. The granular inclusions were by confocal microscopy found to partly colocalize with markers for lysosomes but not with inclusions containing TAR DNA binding protein-43, ubiquitin or markers for endoplasmic reticulum, autophagosomes or mitochondria. Granular inclusions were also found in carriers of SOD1 mutations and in spinobulbar muscular atrophy (SBMA) patients and they were the major type of inclusion detected in ALS patients homozygous for the wild type-like D90A mutation. The findings suggest that SOD1 may be involved in ALS pathogenesis in patients lacking mutations in the enzyme.
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17. |
- Janssen, Xander J. A., et al.
(författare)
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Rapid manufacturing of low-noise membranes for nanopore sensors by trans-chip illumination lithography
- 2012
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Ingår i: Nanotechnology. - : IOP Publishing: Hybrid Open Access. - 0957-4484 .- 1361-6528. ; 23:47
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, the concept of nanopore sensing has matured from a proof-of-principle method to a widespread, versatile technique for the study of biomolecular properties and interactions. While traditional nanopore devices based on a nanopore in a single layer membrane supported on a silicon chip can be rapidly fabricated using standard microfabrication methods, chips with additional insulating layers beyond the membrane region can provide significantly lower noise levels, but at the expense of requiring more costly and time-consuming fabrication steps. Here we present a novel fabrication protocol that overcomes this issue by enabling rapid and reproducible manufacturing of low-noise membranes for nanopore experiments. The fabrication protocol, termed trans-chip illumination lithography, is based on illuminating a membrane-containing wafer from its backside such that a photoresist (applied on the wafers top side) is exposed exclusively in the membrane regions. Trans-chip illumination lithography permits the local modification of membrane regions and hence the fabrication of nanopore chips containing locally patterned insulating layers. This is achieved while maintaining a well-defined area containing a single thin membrane for nanopore drilling. The trans-chip illumination lithography method achieves this without relying on separate masks, thereby eliminating time-consuming alignment steps as well as the need for a mask aligner. Using the presented approach, we demonstrate rapid and reproducible fabrication of nanopore chips that contain small (12 mu m x 12 mu m) free-standing silicon nitride membranes surrounded by insulating layers. The electrical noise characteristics of these nanopore chips are shown to be superior to those of simpler designs without insulating layers and comparable in quality to more complex designs that are more challenging to fabricate.
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18. |
- Jonsson, Magnus P., et al.
(författare)
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Plasmonic Nanopore for Electrical Profiling of Optical Intensity Landscapes
- 2013
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Ingår i: Nano letters (Print). - : American Chemical Society. - 1530-6984 .- 1530-6992. ; 13:3, s. 1029-1033
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel method for sensitive mapping of optical intensity distributions at subdiffraction-limited resolution. This is achieved with a novel device, a plasmonic nanopore, which combines a plasmonic bowtie nanoantenna with a 10 nm-in-diameter solid-state nanopore. Variations in the local optical intensity modulate the plasmonic heating, which we measure electrically through changes in the ionic conductance of the nanopore. We demonstrate the method by profiling the focal volume of a 10 mW laser beam that is tightly focused by a high-numerical-aperture microscope objective. The results show a complex three-dimensional intensity distribution that closely matches predictions obtained by theoretical calculations of the optical system. In addition to laser profiling, the ionic conductance of a nanopore is also shown to provide quantitative estimates of the temperature in the proximity of single plasmonic nanostructures.
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19. |
- Jönsson, Peter, et al.
(författare)
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A Method Improving the Accuracy of Fluorescence Recovery after Photobleaching Analysis
- 2008
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Ingår i: Biophysical Journal. - : Biophysical Society. - 0006-3495 .- 1542-0086. ; 95:11, s. 5334-5348
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescence recovery after photobleaching has been an established technique of quantifying the mobility of molecular species in cells and cell membranes for more than 30 years. However, under nonideal experimental conditions, the current methods of analysis still suffer from occasional problems; for example, when the signal/noise ratio is low, when there are temporal fluctuations in the illumination, or when there is bleaching during the recovery process. We here present a method of analysis that overcomes these problems, yielding accurate results even under nonideal experimental conditions. The method is based on circular averaging of each image, followed by spatial frequency analysis of the averaged radial data, and requires no prior knowledge of the shape of the bleached area. The method was validated using both simulated and experimental fluorescence recovery after photobleaching data, illustrating that the diffusion coefficient of a single diffusing component can be determined to within similar to 1%, even for small signal levels (100 photon counts), and that at typical signal levels (5000 photon counts) a system with two diffusion coefficients can be analyzed with less than 10% error.
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20. |
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21. |
- Li, Yi, et al.
(författare)
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Photoresistance Switching of Plasmonic Nanopores
- 2015
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Ingår i: Nano letters (Print). - : American Chemical Society. - 1530-6984 .- 1530-6992. ; 15:1, s. 776-782
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Tidskriftsartikel (refereegranskat)abstract
- Fast and reversible modulation of ion flow through nanosized apertures is important for many nanofluidic applications, including sensing and separation systems. Here, we present the first demonstration of a reversible plasmon-controlled nanofluidic valve. We show that plasmonic nanopores (solid-state nanopores integrated with metal nanocavities) can be used as a fluidic switch upon optical excitation. We systematically investigate the effects of laser illumination of single plasmonic nanopores and experimentally demonstrate photoresistance switching where fluidic transport and ion flow are switched on or off. This is manifested as a large (similar to 12 orders of magnitude) increase in the ionic nanopore resistance and an accompanying current rectification upon illumination at high laser powers (tens of milliwatts). At lower laser powers, the resistance decreases monotonically with increasing power, followed by an abrupt transition to high resistances at a certain threshold power. A similar rapid transition, although at a lower threshold power, is observed when the power is instead swept from high to low power. This hysteretic behavior is found to be dependent on the rate of the power sweep. The photoresistance switching effect is attributed to plasmon-induced formation and growth of nanobubbles that reversibly block the ionic current through the nanopore from one side of the membrane. This explanation is corroborated by finite-element simulations of a nanobubble in the nanopore that show the switching and the rectification.
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22. |
- Melby, V, et al.
(författare)
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Patient comfort in pre-hospital emergency care : A challenge to clinicians.
- 2012
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Ingår i: Journal of Paramedic Practice. - : M A Healthcare Ltd.. - 1759-1376. ; 4:7, s. 389-399
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The aim of this paper is to report on a study that compared ambulance clinicians' views of two different types of patient coverings, focusing on core caring concepts such as comfort, dignity, and safety. Design: Ambulance clinicians' views were gathered in respect of two types of patient coverings, and 128 ambulance patients were randomly distributed into a control or experimental group receiving respectively either the traditional cotton blanket or a multi-layered TelesPro rescue covering. Views were gathered using a short questionnaire developed by the authors. Findings: Ambulance clinicians, in their own view, maintained the core caring concepts no matter which type of covering was used. Findings suggest strongly that the rescue covering provided for a superior patient experience in respect of all core concepts and one functional aspect. Conclusions: Ambulance clinicians undertake caring that encompasses the core caring concepts of comfort, safety, and dignity, while remaining vigilant to threats to these constituents of caring.
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23. |
- Nordlander, Johan, et al.
(författare)
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Programming with time-constrained reactions
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we argue that a programming language for real-time systems should support the declaration of time-constraints, and that those constraints should attach to a welldeveloped notion of reactions. To make our claims more precise, we introduce Timber, which is a concurrent programming language based on a model of non-blocking, reactive objects. Timber supports both upper and lower time constraints on a reaction, where upper constraints correspond to classical deadlines, and lower constraints constitute the systematic capturing of well-defined points in the future as events in their own right. A series of programming examples illustrates how these mechanisms can be used to express simple solutions to common problems in practical real-time programming, and the relation between Timber and deadline-based scheduling theory is explored.
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24. |
- Persson, C. M., et al.
(författare)
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Testing the Gouy-Chapman theory by means of surface tension measurements for SDS-NaCl-H2O mixtures
- 2003
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 267:1, s. 151-154
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Tidskriftsartikel (refereegranskat)abstract
- Surface tension isotherms were measured for sodium dodecyl sulfate (SDS) at different concentrations of added salt (NaCl). The free energy of the surfactant monolayer was assessed by invoking the Gouy-Chapman theory for the charged head groups, the hydrophobic (Tanford) free energy of transfer of the hydrocarbon chain, and the hydrocarbon chain configurational free energy according to Gruen's calculations and finally macroscopic contact terms. In particular, the effect of an increased salt concentration in bulk was examined. Theoretical predictions compare well with the experimental findings, and good agreement was found with respect to both the variation of free energy of the monolayer and the surface pressure behavior. Thus, at least for a liquid-expanded monolayer of SDS, the Gouy-Chapman model yields a satisfactory account of the electrostatic contribution to the thermodynamic properties at different salt concentrations of NaCl.
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25. |
- Pud, Sergii, et al.
(författare)
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Self-Aligned Plasmonic Nanopores by Optically Controlled Dielectric Breakdown
- 2015
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 15:10, s. 7112-7117
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel cost-efficient method for the fabrication of high-quality self-aligned plasmonic nanopores by means of an optically controlled dielectric breakdown. Excitation of a plasmonic bowtie nanoantenna on a dielectric membrane localizes the high-voltage-driven breakdown of the membrane to the hotspot of the enhanced optical field, creating a nanopore that is automatically self-aligned to the plasmonic hotspot of the bowtie. We show that the approach provides precise control over the nanopore size and that these plasmonic nanopores can be used as single molecule DNA sensors with a performance matching that of TEM-drilled nanopores. The principle of optically controlled breakdown can also be used to fabricate nonplasmonic nanopores at a controlled position. Our novel fabrication process guarantees alignment of the nanopore with the optical hotspot of the nanoantenna, thus ensuring that pore-translocating biomolecules interact with the concentrated optical field that can be used for detection and manipulation of analytes.
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