| 1. |
- Arbring Sjöström, Theresia, 1987-, et al.
(författare)
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Design and Operation of Hybrid Microfluidic Iontronic Probes for Regulated Drug Delivery
- 2021
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Ingår i: Advanced Materials Technologies. - Hoboken, New Jersey : John Wiley & Sons. - 2365-709X. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- Highly controlled drug delivery devices play an increasingly important role in the development of new neuroengineering tools. Stringent - and sometimes contradicting - demands are placed on such devices, ranging from robustness in freestanding devices, to overall device miniaturization, while maintaining precise spatiotemporal control of delivery with high chemical specificity and high on/off ratio. Here, design principles of a hybrid microfluidic iontronic probe that uses flow for long-range pressure-driven transport in combination with an iontronic tip that provides electronically fine-tuned pressure-free delivery are explored. Employing a computational model, the effects of decoupling the drug reservoir by exchanging a large passive reservoir with a smaller microfluidic system are reported. The transition at the microfluidic-iontronic interface is found to require an expanded ion exchange membrane inlet in combination with a constant fluidic flow, to allow a broad range of device operation, including low source concentrations and high delivery currents. Complementary to these findings, the free-standing hybrid probe monitored in real time by an external sensor is demonstrated. From these computational and experimental results, key design principles for iontronic devices are outlined that seek to use the efficient transport enabled by microfluidics, and further, key observations of hybrid microfluidic iontronic probes are explained.
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| 2. |
- Berggren, Karl-Fredrik, et al.
(författare)
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Crossover from regular to irregular behavior in current flow through open billiards
- 2002
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Ingår i: Physical Review E - Statistical, Nonlinear, and Soft Matter Physics. - 1539-3755. ; 66:1
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Tidskriftsartikel (refereegranskat)abstract
- We discuss signatures of quantum chaos in terms of distributions of nodal points, saddle points, and streamlines for coherent electron transport through two-dimensional billiards, which are either nominally integrable or chaotic. As typical examples of the two cases we select rectangular and Sinai billiards. We have numerically evaluted distribution functions for nearest distances between nodal points and found that there is a generic form for open chaotic billiards through which a net current is passed. We have also evaluated the distribution functions for nodal points with specific vorticity (winding number) as well as for saddle points. The distributions may be used as signatures of quantum chaos in open systems. All distributions are well reproduced using random complex linear combinations of nearly monochromatic states in nominally closed billiards. In the case of rectangular billiards with simple sharp-cornered leads the distributions have characteristic features related to order among the nodal points. A flaring or rounding of the contact regions may, however, induce a crossover to nodal point distributions and current flow typical for quantum chaos. For an irregular arrangement of nodal points, as for example in the Sinai billiard, the quantum flow lines become very complex and volatile, recalling chaos among classical trajectories. Similarities with percolation are pointed out. ©2002 The American Physical Society.
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| 3. |
- Berggren, Karl-Fredrik, et al.
(författare)
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Quantum chaos among nodal points and streamlines at ballistic electron transport through open quantum dots
- 2001
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 12:4, s. 562-565
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We trace signatures of quantum chaos in the distribution of nodal points and streamlines for coherent electron transport through different types of quantum dots (chaotic and regular). We have calculated normalized distribution functions for the nearest distances between nodal points and found that this distribution may be used as a signature of quantum chaos for electron transport in open systems. Different chaotic billiards show the same characteristic distribution function for nodal points. This signature of quantum chaos is well reproduced using well known approaches for chaotic wavefunctions. We have also investigated the quantum flows which display some remarkable features.
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| 4. |
- Björnqvist, Anton, 1995-, et al.
(författare)
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An Analysis of a Swedish Medical Command and Control System’s Situation Reports from the COVID-19 Pandemic
- 2022
-
Ingår i: ISCRAM 2022 Conference Proceedings – 19th International Conference on Information Systems for Crisis Response and Management. - 9788284270999 ; , s. 334-348
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Konferensbidrag (refereegranskat)abstract
- This paper presents an analysis of situation reports used and created by a crisis management team within the Swedish healthcare sector during the early phase of the COVID-19 pandemic. The analysis was conducted through a deductive content analysis, where categories were identified based on the concepts of common operational pictures, sensemaking, and situation awareness. In the analysis, support for all identified categories was found. Based on the analysis and the concepts, future recommendations regarding what type of information that ought to be included in situation reports were created. These recommendations include, amongst others, the categories of consequences, how it is perceived by the public, objectives, status and implications of information, future scenarios, actions, resources, and work procedures.
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| 5. |
- Björnqvist, Anton, 1995-, et al.
(författare)
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Identifying Teamwork Processes in a Medical Command and Control Team During the COVID-19 Pandemic
- 2023
-
Ingår i: Proceedings of the 20th International ISCRAM Conference. - Omaha, USA. ; , s. 711-720
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Konferensbidrag (refereegranskat)abstract
- This paper presents an ethnographic study consisting of non-participatory observations of a Swedish regional medical command and control team during their crisis response to the COVID-19 pandemic. The field-notes from the observations were analyzed using a deductive content analysis with categories representing teamwork processes. The content analysis showed that the studied regional medical command and control team was engaged in all but one of the predefined teamwork processes. Furthermore, the content analysis also added to the understanding of the regional medical command and control teamÂ’s work procedures by emphasizing how the team was engaged in the different processes. Lastly, the content analysis also made it possible to identify potential developmental needs of the studied regional medical command and control team.
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| 6. |
- Erdmann, Tim, et al.
(författare)
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Naphthalenediimide Polymers with Finely Tuned In-Chain pi-Conjugation: Electronic Structure, Film Microstructure, and Charge Transport Properties
- 2016
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Ingår i: ADVANCED MATERIALS. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 28:41, s. 9169-
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Tidskriftsartikel (refereegranskat)abstract
- Naphthalenediimide-based random copolymers (PNDI-TVTx) with different p-conjugated dithienylvinylene (TVT) versus p-nonconjugated dithienylethane (TET) unit ratios (x = 100 -amp;gt; 0%) are investigated. The PNDI-TVTx-transistor electron/hole mobilities are affected differently, a result rationalized by molecular orbital topologies and energies, with hole mobility vanishing but electron mobility decreasing only by approximate to 2.5 times when going from x = 100% to 40%.
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| 7. |
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| 8. |
- Lindhagen, Alva, et al.
(författare)
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Supporting Instructors in Conducting Exercises
- 2023
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Ingår i: Proceedings of the 20th International ISCRAM Conference. - Omaha, USA. ; , s. 721-731
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Konferensbidrag (refereegranskat)abstract
- Planning, designing, facilitating, and evaluating are central activities for instructors when conducting exercises.When conducting these activities, instructors usually rely on past experiences since structured educations orguides for instructors do not exist. It is therefore evident that there is a need for such educations or guides.In this study, the contents of a guide for instructors are proposed. The contents are based on seven semi-structuredinterviews with novel and experienced instructors, where they were asked to map their procedures for conductingexercises through a journey map. The interviews resulted in material which was transcribed and analysed using athematic analysis. The thematic analysis emphasized five themes to consider when acting as an instructor, namelyroles, realism, defining purpose and goals, learning, and planning and acting.The results from the interviews, combined with past literature, resulted in proposed contents for an instructor’sguide which is currently being developed.
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| 9. |
- Linhagen, Alva, et al.
(författare)
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A Meta-evaluation of Swedish Evaluations of COVID-19 Pandemic Management
- 2022
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Ingår i: ISCRAM 2022 Conference Proceedings – 19th International Conference on Information Systems for Crisis Response and Management. - 9788284270999 ; , s. 349-361
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Konferensbidrag (refereegranskat)abstract
- The COVID-19 pandemic has had a global impact om society. Different countries and organizations have chosen different approaches to manage this crisis. This paper aims to describes how public Swedish actors (county administrative boards, municipalities, and regional councils) evaluated their management of the COVID-19 pandemic. Also, the paper aims to suggest improvements for crisis management strategies. Applying a meta-evaluation approach to open reports from the public organizations means collecting evaluation reports, determining if they fit the inclusion criteria, and if so, include them in the analysis. Included reports were categorized and given points indicating different types of merits. In addition, a thematic analysis of conclusions was conducted. 110 evaluation reports from 98 different organizations are included in the analysis. The importance of evaluating, having a structure for data collection, analysis, and reporting is reflected in the quality of the reports. Four identified themes offer an understanding of areas in need for development among Swedish regional councils, municipalities, and county administrative boards.
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| 10. |
- Munch, Marie W., et al.
(författare)
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Effect of 12 mg vs 6 mg of Dexamethasone on the Number of Days Alive Without Life Support in Adults With COVID-19 and Severe Hypoxemia The COVID STEROID 2 Randomized Trial
- 2021
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Ingår i: Journal of the American Medical Association (JAMA). - : AMER MEDICAL ASSOC. - 0098-7484 .- 1538-3598. ; 326:18, s. 1807-1817
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Tidskriftsartikel (refereegranskat)abstract
- Question What is the effect of 12 mg vs 6 mg of dexamethasone on the number of days alive without life support at 28 days in patients with COVID-19 and severe hypoxemia? Findings In this randomized trial that included 1000 patients with COVID-19 and severe hypoxemia, treatment with 12 mg/d of dexamethasone resulted in 22.0 days alive without life support at 28 days compared with 20.5 days in those receiving 6 mg/d of dexamethasone. This difference was not statistically significant. Meaning Compared with 6 mg of dexamethasone, 12 mg of dexamethasone did not statistically significantly reduce the number of days alive without life support at 28 days. This multicenter randomized clinical trial compares the effects of 12 mg/d vs 6 mg/d of dexamethasone in patients with COVID-19 and severe hypoxemia. IMPORTANCE A daily dose with 6 mg of dexamethasone is recommended for up to 10 days in patients with severe and critical COVID-19, but a higher dose may benefit those with more severe disease. OBJECTIVE To assess the effects of 12 mg/d vs 6 mg/d of dexamethasone in patients with COVID-19 and severe hypoxemia. DESIGN, SETTING, AND PARTICIPANTS A multicenter, randomized clinical trial was conducted between August 2020 and May 2021 at 26 hospitals in Europe and India and included 1000 adults with confirmed COVID-19 requiring at least 10 L/min of oxygen or mechanical ventilation. End of 90-day follow-up was on August 19, 2021. INTERVENTIONS Patients were randomized 1:1 to 12 mg/d of intravenous dexamethasone (n = 503) or 6 mg/d of intravenous dexamethasone (n = 497) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was the number of days alive without life support (invasive mechanical ventilation, circulatory support, or kidney replacement therapy) at 28 days and was adjusted for stratification variables. Of the 8 prespecified secondary outcomes, 5 are included in this analysis (the number of days alive without life support at 90 days, the number of days alive out of the hospital at 90 days, mortality at 28 days and at 90 days, and >= 1 serious adverse reactions at 28 days). RESULTS Of the 1000 randomized patients, 982 were included (median age, 65 [IQR, 55-73] years; 305 [31%] women) and primary outcome data were available for 971 (491 in the 12 mg of dexamethasone group and 480 in the 6 mg of dexamethasone group). The median number of days alive without life support was 22.0 days (IQR, 6.0-28.0 days) in the 12 mg of dexamethasone group and 20.5 days (IQR, 4.0-28.0 days) in the 6 mg of dexamethasone group (adjusted mean difference, 1.3 days [95% CI, 0-2.6 days]; P = .07). Mortality at 28 days was 27.1% in the 12 mg of dexamethasone group vs 32.3% in the 6 mg of dexamethasone group (adjusted relative risk, 0.86 [99% CI, 0.68-1.08]). Mortality at 90 days was 32.0% in the 12 mg of dexamethasone group vs 37.7% in the 6 mg of dexamethasone group (adjusted relative risk, 0.87 [99% CI, 0.70-1.07]). Serious adverse reactions, including septic shock and invasive fungal infections, occurred in 11.3% in the 12 mg of dexamethasone group vs 13.4% in the 6 mg of dexamethasone group (adjusted relative risk, 0.83 [99% CI, 0.54-1.29]). CONCLUSIONS AND RELEVANCE Among patients with COVID-19 and severe hypoxemia, 12 mg/d of dexamethasone compared with 6 mg/d of dexamethasone did not result in statistically significantly more days alive without life support at 28 days. However, the trial may have been underpowered to identify a significant difference.
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| 11. |
- Obst, Matthias, 1974, et al.
(författare)
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Marine long-term biodiversity assessment suggests loss of rare species in the Skagerrak and Kattegat region
- 2018
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Ingår i: Marine Biodiversity. - : Springer Science and Business Media LLC. - 1867-1616 .- 1867-1624. ; 48:4, s. 2165-2176
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 The Author(s) Studies of cumulative and long-term effects of human activities in the ocean are essential for developing realistic conservation targets. Here, we report the results of a recent national marine biodiversity inventory along the Swedish West coast between 2004 and 2009. The expedition revisited many historical localities that have been sampled with the same methods in the early twentieth century. We generated comparable datasets from our own investigation and the historical data to compare species richness, abundance, and geographic distribution of diversity. Our analysis indicates that the benthic ecosystems in the region have lost a large part of its original species richness over the last seven decades. We find evidence that especially rare species have disappeared. This process has caused a more homogenized community structure in the region and diminished historical biodiversity hotspots. We argue that the contemporary lack of rare species in the benthic ecosystems of the Kattegat and Skagerrak offers less opportunity to respond to environmental perturbations in the future and suggest improving the poor representation of rare species in the region. The study shows the value of biodiversity inventories as well as natural history collections in investigations of accumulated effects of anthropogenic activities and for re-establishing species-rich, productive, and resilient ecosystems.
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| 12. |
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| 13. |
- Saghaleyni, Rasool, 1987, et al.
(författare)
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Enhanced metabolism and negative regulation of ER stress support higher erythropoietin production in HEK293 cells
- 2022
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 39:11
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Tidskriftsartikel (refereegranskat)abstract
- Recombinant protein production can cause severe stress on cellular metabolism, resulting in limited titer and product quality. To investigate cellular and metabolic characteristics associated with these limitations, we compare HEK293 clones producing either erythropoietin (EPO) (secretory) or GFP (non-secretory) protein at different rates. Transcriptomic and functional analyses indicate significantly higher metabolism and oxidative phosphorylation in EPO producers compared with parental and GFP cells. In addition, ribosomal genes exhibit specific expression patterns depending on the recombinant protein and the production rate. In a clone displaying a dramatically increased EPO secretion, we detect higher gene expression related to negative regulation of endoplasmic reticulum (ER) stress, including upregulation of ATF6B, which aids EPO production in a subset of clones by overexpression or small interfering RNA (siRNA) knockdown. Our results offer potential target pathways and genes for further development of the secretory power in mammalian cell factories.
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| 14. |
- Starikov, Anton, et al.
(författare)
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Effects of accidental microconstriction on the quantized conductance in long wires
- 2003
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5023, s. 267-270
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have investigated the conductance of long quantum wires formed in GaAs/ AlxGa1-x As heterostructures. Using realistic fluctuation potentials from donor layers we have simulated numerically the conductance of four different kinds of wires. While ideal wires show perfect quantization, potential fluctuations from random donors may give rise to strong conductance oscillations and degradation of the quantization plateaux. Statistically there is always the possibility of having large fluctuations in a sample that may effectively act as a microconstriction. We therefore introduce microconstrictions in the wires by occasional clustering of donors. These microconstrictions are found to restore the quantized plateaux. A similar effect is found for accidental lithographic inaccuracies.
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| 15. |
- Starikov, Anton, et al.
(författare)
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Scenario for the 0.7-conductance anomaly in quantum point contacts
- 2003
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 67:23
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Tidskriftsartikel (refereegranskat)abstract
- Effects of spontaneous spin polarization in quantum point contacts (QPC's) are investigated for a realistic semiconductor device structure using the Kohn-Sham local spin-density formalism. At maximal polarization in the contact area, there is a bifurcation into ground-state and metastable solutions. The conduction associated with the metastability is lower than for the normal state. With increasing temperature, the conductance should therefore show an anomalous behavior as observed. For the present device we do not recover resonance or quasibound states.
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| 16. |
- 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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| 17. |
- Volkov, Anton, 1989-
(författare)
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Ionic and electronic transport in electrochemical and polymer based systems
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Electrochemical systems, which rely on coupled phenomena of the chemical change and electricity, have been utilized for development an interface between biological systems and conventional electronics. The development and detailed understanding of the operation mechanism of such interfaces have a great importance to many fields within life science and conventional electronics. Conducting polymer materials are extensively used as a building block in various applications due to their ability to transduce chemical signal to electrical one and vice versa. The mechanism of the coupling between the mass and charge transfer in electrochemical systems, and particularly in conductive polymer based system, is highly complex and depends on various physical and chemical properties of the materials composing the system of interest.The aims of this thesis have been to study electrochemical systems including conductive polymer based systems and provide knowledge for future development of the devices, which can operate with both chemical and electrical signals. Within the thesis, we studied the operation mechanism of ion bipolar junction transistor (IBJT), which have been previously utilized to modulate delivery of charged molecules. We analysed the different operation modes of IBJT and transition between them on the basis of detailed concentration and potential profiles provided by the model.We also performed investigation of capacitive charging in conductive PEDOT:PSS polymer electrode. We demonstrated that capacitive charging of PEDOT:PSS electrode at the cyclic voltammetry, can be understood within a modified Nernst-Planck-Poisson formalism for two phase system in terms of the coupled ion-electron diffusion and migration without invoking the assumption of any redox reactions.Further, we studied electronic structure and optical properties of a self-doped p-type conducting polymer, which can polymerize itself along the stem of the plants. We performed ab initio calculations for this system in undoped, polaron and bipolaron electronic states. Comparison with experimental data confirmed the formation of undoped or bipolaron states in polymer film depending on applied biases.Finally, we performed simulation of the reduction-oxidation reaction at microband array electrodes. We showed that faradaic current density at microband array electrodes increases due to non-linear mass transport on the microscale compared to the corresponding macroscale systems. The studied microband array electrode was used for developing a laccase-based microband biosensor. The biosensor revealed improved analytical performance, and was utilized for in situ phenol detection.
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| 18. |
- Volkov, Anton, et al.
(författare)
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Modeling of Charge Transport in Ion Bipolar Junction Transistors
- 2014
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 30:23, s. 6999-7005
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Tidskriftsartikel (refereegranskat)abstract
- Spatiotemporal control of the complex chemical microenvironment is of great importance to many fields within life science. One way to facilitate such control is to construct delivery circuits, comprising arrays of dispensing outlets, for ions and charged biomolecules based on ionic transistors. This allows for addressability of ionic signals, which opens up for spatiotemporally controlled delivery in a highly complex manner. One class of ionic transistors, the ion bipolar junction transistors (IBJTs), is especially attractive for these applications because these transistors are functional at physiological conditions and have been employed to modulate the delivery of neurotransmitters to regulate signaling in neuronal cells. Further, the first integrated complementary ionic circuits were recently developed on the basis of these ionic transistors. However, a detailed understanding of the device physics of these transistors is still lacking and hampers further development of components and circuits. Here, we report on the modeling of IBJTs using Poissons and Nernst-Planck equations and the finite element method. A two-dimensional model of the device is employed that successfully reproduces the main characteristics of the measurement data. On the basis of the detailed concentration and potential profiles provided by the model, the different modes of operation of the transistor are analyzed as well as the transitions between the different modes. The model correctly predicts the measured threshold voltage, which is explained in terms of membrane potentials. All in all, the results provide the basis for a detailed understanding of IBJT operation. This new knowledge is employed to discuss potential improvements of ion bipolar junction transistors in terms of miniaturization and device parameters.
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| 19. |
- Volkov, Anton, et al.
(författare)
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Spectroelectrochemistry and Nature of Charge Carriers in Self-Doped Conducting Polymer
- 2017
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Ingår i: Advanced Electronic Materials. - : Wiley-VCH Verlagsgesellschaft. - 2199-160X. ; 3:8
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Tidskriftsartikel (refereegranskat)abstract
- A recently developed water-soluble self-doped sodium salt of bis[3,4-ethylenedioxythiophene] 3thiophene butyric acid (ETE-S) is electropolymerized and characterized by means of spectroelectrochemistry, electron paramagnetic resonance spectroscopy, and cyclic voltammetry, combined with the density functional theory (DFT) and time-dependent DFT calculations. The focus of the studies is to underline the nature of the charge carriers when the electrochemically polymerized ETE-S films undergo a reversible transition from reduced to electrically conductive oxidized states. Spectroelectrochemistry shows clear distinctions between absorption features from reduced and charged species. In the reduced state, the absorption spectrum of ETE-S electropolymerized film shows a peak that is attributed to HOMO. LUMO transition. As the oxidation level increases, this peak diminishes and the absorption of the film is dominated by spinless bipolaronic states with some admixture of polaronic states possessing a magnetic momentum. For fully oxidized samples, the bipolaronic states fully dominate, and the features in the absorption spectra are related to the drastic changes of the band structure, exhibiting a strong decrease of the band gap when a polymeric film undergoes oxidation.
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| 20. |
- Volkov, Anton, et al.
(författare)
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Understanding the Capacitance of PEDOT:PSS
- 2017
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Ingår i: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-301X .- 1616-3028. ; 27:28
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Tidskriftsartikel (refereegranskat)abstract
- Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is the most studied and explored mixed ion-electron conducting polymer system. PEDOT: PSS is commonly included as an electroactive conductor in various organic devices, e.g., supercapacitors, displays, transistors, and energy-converters. In spite of its long-term use as a material for storage and transport of charges, the fundamentals of its bulk capacitance remain poorly understood. Generally, charge storage in supercapacitors is due to formation of electrical double layers or redox reactions, and it is widely accepted that PEDOT: PSS belongs to the latter category. Herein, experimental evidence and theoretical modeling results are reported that significantly depart from this commonly accepted picture. By applying a two-phase, 2D modeling approach it is demonstrated that the major contribution to the capacitance of the two-phase PEDOT: PSS originates from electrical double layers formed along the interfaces between nanoscaled PEDOT-rich and PSS-rich interconnected grains that comprises two phases of the bulk of PEDOT: PSS. This new insight paves a way for designing materials and devices, based on mixed ion-electron conductors, with improved performance.
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| 21. |
- Wang, Suhao, et al.
(författare)
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A Chemically Doped Naphthalenediimide-Bithiazole Polymer for n-Type Organic Thermoelectrics
- 2018
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 30:31
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of a novel naphthalenediimide (NDI)-bithiazole (Tz2)-based polymer [P(NDI2OD-Tz2)] is reported, and structural, thin-film morphological, as well as charge transport and thermoelectric properties are compared to the parent and widely investigated NDI-bithiophene (T2) polymer [P(NDI2OD-T2)]. Since the steric repulsions in Tz2 are far lower than in T2, P(NDI2OD-Tz2) exhibits a more planar and rigid backbone, enhancing p-p chain stacking and intermolecular interactions. In addition, the electron-deficient nature of Tz2 enhances the polymer electron affinity, thus reducing the polymer donor-acceptor character. When n-doped with amines, P(NDI2OD-Tz2) achieves electrical conductivity (approximate to 0.1 S cm(-1)) and a power factor (1.5 mu W m(-1) K-2) far greater than those of P(NDI2OD-T2) (0.003 S cm(-1) and 0.012 mu W m(-1) K-2, respectively). These results demonstrate that planarized NDI-based polymers with reduced donor-acceptor character can achieve substantial electrical conductivity and thermoelectric response.
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| 22. |
- Westman, Anton, 1972-, et al.
(författare)
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Parachuting from fixed objects : descriptive study of 106 fatal events in BASE jumping 1981-2006
- 2008
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Ingår i: British Journal of Sports Medicine. - Loughborough : British Assoc. of Sport and Medicine. - 0306-3674 .- 1473-0480. ; 42:6, s. 431-436
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To analyse the characteristics of fatal incidents in fixed object sport parachuting (building, antenna, span, earth (BASE) jumping) and create a basis for prevention.Design: Descriptive epidemiological study.Participants: Data on reported fatal injury events (n = 106) worldwide in 1981–2006 retrieved from the BASE fatality list.Assessment of risk factors: Human, equipment and environmental factors.Main outcome measurements: Identification of typical fatal incident and injury mechanisms for each of the four fixed object types of BASE jumping (building, antenna, span, earth).Results: Human factors included parachutist free fall instability (loss of body control before parachute deployment), free fall acrobatics and deployment failure by the parachutist. Equipment factors included pilot chute malfunction and parachute malfunction. In cliff jumping (BASE object type E), parachute opening towards the object jumped was the most frequent equipment factor. Environmental factors included poor visibility, strong or turbulent winds, cold and water. The overall annual fatality risk for all object types during the year 2002 was estimated at about one fatality per 60 participants.Conclusions: Participants in BASE jumping should target risk factors with training and technical interventions. The mechanisms described in this study should be used by rescue units to improve the management of incidents.
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| 23. |
- Williamson, Adam, et al.
(författare)
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Controlling Epileptiform Activity with Organic Electronic Ion Pumps
- 2015
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Ingår i: Advanced Materials. - : Wiley-VCH Verlag. - 0935-9648 .- 1521-4095. ; 27:20, s. 3138-3144
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Tidskriftsartikel (refereegranskat)abstract
- In treating epilepsy, the ideal solution is to act at a seizure's onset, but only in the affected regions of the brain. Here, an organic electronic ion pump is demonstrated, which directly delivers on-demand pure molecules to specific brain regions. State-of-the-art organic devices and classical pharmacology are combined to control pathological activity in vitro, and the results are verified with electrophysiological recordings.
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| 24. |
- Yedeg, Esubalewe Lakie, 1983-
(författare)
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Analysis, Control, and Design Optimization of Engineering Mechanics Systems
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis considers applications of gradient-based optimization algorithms to the design and control of some mechanics systems. The material distribution approach to topology optimization is applied to design two different acoustic devices, a reactive muffler and an acoustic horn, and optimization is used to control a ball pitching robot.Reactive mufflers are widely used to attenuate the exhaust noise of internal combustion engines by reflecting the acoustic energy back to the source. A material distribution optimization method is developed to design the layout of sound-hard material inside the expansion chamber of a reactive muffler. The objective is to minimize the acoustic energy at the muffler outlet. The presence or absence of material is represented by design variables that are mapped to varying coefficients in the governing equation. An anisotropic design filter is used to control the minimum thickness of materials separately in different directions. Numerical results demonstrate that the approach can produce mufflers with high transmission loss for a broad range of frequencies.For acoustic devices, it is possible to improve their performance, without adding extended volumes of materials, by an appropriate placement of thin structures with suitable material properties. We apply layout optimization of thin sound-hard material in the interior of an acoustic horn to improve its far-field directivity properties. Absence or presence of thin sound-hard material is modeled by a surface transmission impedance, and the optimization determines the distribution of materials along a “ground structure” in the form of a grid inside the horn. Horns provided with the optimized scatterers show a much improved angular coverage, compared to the initial configuration.The surface impedance is handled by a new finite element method developed for Helmholtz equation in the situation where an interface is embedded in the computational domain. A Nitschetype method, different from the standard one, weakly enforces the impedance conditions for transmission through the interface. As opposed to a standard finite-element discretization of the problem, our method seamlessly handles both vanishing and non-vanishing interface conditions. We show the stability of the method for a quite general class of surface impedance functions, provided that possible surface waves are sufficiently resolved by the mesh.The thesis also presents a method for optimal control of a two-link ball pitching robot with the aim of throwing a ball as far as possible. The pitching robot is connected to a motor via a non-linear torsional spring at the shoulder joint. Constraints on the motor torque, power, and angular velocity of the motor shaft are included in the model. The control problem is solved by an interior point method to determine the optimal motor torque profile and release position. Numerical experiments show the effectiveness of the method and the effect of the constraints on the performance.
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