| 1. |
- Berggren, Lars, et al.
(författare)
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Förord
- 2010
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Ingår i: Samhällshistoria i fokus. En festskrift till Lars Olsson om arbete, migration och kultur. - 9789197898003 ; , s. 11-15
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 2. |
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| 3. |
- Yu, Xingang, et al.
(författare)
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Single-mode InGaAs/GaAs 1.3-mu m VCSELs Based on a Shallow Intracavity Patterning
- 2010
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Ingår i: SEMICONDUCTOR LASERS AND LASER DYNAMICS IV. - : SPIE. - 9780819481931 ; , s. 772021-
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Konferensbidrag (refereegranskat)abstract
- A high-power single-mode 1.3-mu m InGaAs/GaAs vertical-cavity surface-emitting laser (VCSEL) structure employing a novel concept of engineering the optical mode profile to match the gain profile is suggested and demonstrated experimentally and theoretically. In contrast to various singlemode VCSEL approaches reported in the literature so far, based on selective loss or anti-resonant effects to suppress higher order modes, it is due to a novel design to increase the active region size while maintaining single mode emission. The shape of the fundamental mode profile is engineered to be similar to the gain profile which resembles a doughnut shape especially in intra-cavity contacted devices. In this way, the fundamental mode with the best fit to the gain profile can reach the lasing condition earliest and consume all the optical gain, leading to a suppression of higher order modes. Notably, despite this engineered shape of the mode profile, the far field shape remains close to Gaussian. The mode shaping can be achieved by introducing a shallow intracavity patterning before depositing the top mirror. Fabricated device structures consist of a A-Si/SiN/SiO(2) top mirror, modulation-doped current spreading layers, re-grown current confinement layers, three InGaAs/GaAs quantum wells, and a GaAs/AlGaAs bottom mirror. Single mode operation is demonstrated even for devices with active region as large as 10 mu m.
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| 4. |
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| 5. |
- Akram, Nadeem, et al.
(författare)
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Design optimization of InGaAsP-InGaAlAs 1.55 mu;m strain-compensated MQW lasers for direct modulation applications
- 2004
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Ingår i: Indium Phosphide and Related Materials, 2004. 16th IPRM. 2004 International Conference on. - : IEEE. - 0780385950 ; , s. 418-421
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Konferensbidrag (refereegranskat)abstract
- A comprehensive simulation study of InGaAsP (well)/InGaAlAs(barrier) 1.55 mu;m strain-compensated MQW lasers is presented. For MQWs, a uniform vertical distribution of holes is achieved due to a reduced effective hole confinement energy by optimizing the bandgap and strain of the barriers and p-doping in the active region. Some preliminary results are also presented for the manufactured lasers using these QWs indicating a good material platform.
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| 6. |
- Akram, Nadeem, 1971-, et al.
(författare)
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Experimental characterization of high-speed 1.55 mu m buried heterostructure InGaAsP/InGaAlAs quantum-well lasers
- 2009
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Ingår i: Journal of the Optical Society of America. B, Optical physics. - 0740-3224 .- 1520-8540. ; 26:2, s. 318-327
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Tidskriftsartikel (refereegranskat)abstract
- Detailed experimental characterization is performed for 1550 nm semi-insulating regrown buried heterostructure Fabry-Perot (FP) lasers having 20 InGaAsP/InGaAlAs strain-balanced quantum wells (QWs) in the active region. Light-current-voltage performance, electrical impedance, small-signal response below and above threshold, amplified spontaneous emission spectrum below threshold and relative intensity noise spectrum are measured. Different laser parameters such as external differential quantum efficiency eta(d), background optical loss alpha(i), K-factor, D-factor, characteristic temperature T-0, differential gain dg/dn, gain-compression factor epsilon, carrier density versus current, differential carrier lifetime tau(d), optical gain spectrum below threshold, and chirp parameter alpha are extracted from these measurements. The FP lasers exhibited a high T-0 (78-86.5 degrees C) and very high-resonance frequency (23.7 GHz). The results indicate that appropriately designed lasers having a large number of InGaAsP well/InGaAlAs barrier QWs with shallow valence-band discontinuity can be useful for un-cooled high-speed direct-modulated laser applications.
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| 7. |
- Akram, Nadeem, 1971-, et al.
(författare)
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High-Speed Performance of 1.55 µm Buried Hetero-Structure Lasers with 20 InGaAsP/InGaAlAs Quantum-Wells
- 2006
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Ingår i: 2006 European Conference on Optical Communications Proceedings, ECOC 2006. - : IEEE. - 9782912328397 ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- 1550 nm re-grown FP lasers having 20 InGaAsP/InGaAlAs strain-balanced QWs exhibit low threshold current density, high T0 (78.0 #x000B0;C) and high resonance frequency (24 GHz) indicating that a large number of shallow barrier QWs are attractive for un-cooled high-speed direct-modulation applications.
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| 8. |
- Akram, Nadeem, et al.
(författare)
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The effect of barrier composition on the vertical carrier transport and lasing properties of 1.55-mu m multiple quantum-well structures
- 2006
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Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 42:7, s. 713-714
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the effect of barrier bandgap and composition on the optical performance of 1.55-mu m InGaAsP/In-GaAsP and InGaAsP/InGaAlAs multiple quantum-well structures and Fabry-Perot lasers is evaluated experimentally. Direct vertical carrier transport measurements were performed through strain-compensated multiple quantum-well (MQW) test structures using femto-second laser pulse excitation and time-resolved photoluminescence up-conversion method. MQW test structures were grown with different barrier composition (InGaAsP and InGaAlAs) and barrier bandgap (varied from lambda(g) = 1440 to 1260 nm) having different conduction band Delta E-c and valence band discontinuity Delta E-v, while keeping the same InGaAsP well composition for all the structures. The ambipolar carrier transport was found to be faster in the structures with lower valence band discontinuity Delta E-v. Regrown semi-insulating buried heterostructure Fabry-Perot (SIBH-FP) lasers were fabricated from similar QWs and their static light-current-voltage characteristics (including optical gain and chirp spectra below threshold) and thermal characteristics were measured. Lasers with InGaAlAs barrier showed improved high-temperature operation, higher optical gain, higher differential gain, and lower chirp, making them suitable candidates for high-bandwidth directly modulated uncooled laser applications.
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| 9. |
- Arnrup, K, et al.
(författare)
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Classification of dental behavior management problems among children.
- 2007
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Ingår i: Poster presentation at the 85th General Session & Exhibition of the IADR, New Orleans, LA, USA, March 21-24, 2007..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Objectives: This study aimed to further investigate the heterogeneity within the group of children referred for specialist treatment because of dental behavior management problems (DBMP). A specific aim was to evaluate the validity of a previously reported cluster structure in another DBMP study group. Methods: 177 child dental patients, aged 4 to 12 at referral to a specialist pediatric dental clinic in Göteborg, Sweden, were classified into subgroups according to their personal characteristics. Cluster structure was described and compared to previously reported findings in a DBMP study group of same-aged child dental patients in Örebro, Sweden (n=74). Parental assessments of children's dental and general fear, temperament and behavior were made pre-treatment. The children also performed a vocabulary test. Data were analyzed mainly with a person-based approach using sequences of cluster analyses. Results: Classification into five different subgroups was judged the best representation of the Göteborg study group data, while four groups had been defined in Örebro. The new clusters partly paralleled the previous and were labeled (I) Extrovert, outgoing, (II) Highly fearful, multiple problems, (III) Highly fearful, (IV) Moderately fearful, externalizing, impulsive and (V) Moderately fearful, inhibited. Cluster profile II describes severe dental fear and general temperamental and behavioral problems of internalizing as well as externalizing character. Such combined problems were not clearly revealed in the Örebro cluster structure. Conclusion: The contention that children with dental behavior management problems (DBMP) comprise a heterogeneous group was strengthened. Similar, although not identical, clusters of children showing DBMP were identified in this replication study. Apart from different levels of dental fear, varying temperamental and behavioral characteristics need to be taken into consideration to better match treatment for these patients
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| 10. |
- Belaineh Yilma, Dagmawi, et al.
(författare)
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Printable carbon-based supercapacitors reinforced with cellulose and conductive polymers
- 2022
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Ingår i: Journal of Energy Storage. - : Elsevier Ltd. - 2352-152X .- 2352-1538. ; 50
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Tidskriftsartikel (refereegranskat)abstract
- Sustainable electrical energy storage is one of the most important scientific endeavors of this century. Battery and supercapacitor technologies are here crucial, but typically the current state of the art suffers from either lack of large-scale production possibilities, sustainability or insufficient performance and hence cannot match growing demands in society. Paper and cellulosic materials are mature scalable templates for industrial roll-to-roll production. Organic materials, such as conducting polymers, and carbon derivatives are materials that can be synthesized or derived from abundant sources. Here, we report the combination of cellulose, PEDOT:PSS and carbon derivatives for bulk supercapacitor electrodes adapted for printed electronics. Cellulose provides a mesoscopic mesh for the organization of the active ingredients. Furthermore, the PEDOT:PSS in combination with carbon provides superior device characteristics when comparing to the previously standard combination of activated carbon and carbon black. PEDOT:PSS acts as a mixed ion-electron conducting glue, which physically binds activated carbon particles together, while at the same time facilitating swift transport of both electrons and ions. A surprisingly small amount (10%) of PEDOT:PSS is needed to achieve an optimal performance. This work shows that cellulose added to PEDOT:PSS-carbon enables high-performing, mechanically stable, printed supercapacitor electrodes using a combination of printing methods.
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| 11. |
- Berggren, David, et al.
(författare)
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Förnyelselagen - möjlighet eller hot?
- 2018
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Ingår i: Samhällsbyggaren. - Stockholm : Samhällsbyggarna Sverige AB. - 2000-2408. ; 27 maj:2, s. 38-39
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Riksdagen har beslutat att avtalsrättigheter som skrivits in i det statliga Lantmäteriets fastighetsregister före den 1 juli 1968 kommer att tas bort ur registret om inte rättighetshavaren senast den 31 december 2018 anmäler till Lantmäteriet att den ska finnas kvar. Hur arbetar rättighetshavare med förnyelsekravet och vad kan förnyelsekravet väntas få för konsekvenser?
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| 12. |
- Berggren, Lars, et al.
(författare)
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Electrical Conductivity as a Function of Temperature in Amorphous Lithium Tungsten Oxide
- 2004
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 84:1, s. 329-336
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Tidskriftsartikel (refereegranskat)abstract
- Tungsten oxide is a widely used electrochromic material for smart windows. In order to study the charge carriers involved in the electrochromic process, it is important to characterize the electrical transport in tungsten oxide. Substoichiometric amorphous tungsten oxide films were prepared by DC-magnetron sputtering. The films were electrochemically intercalated with lithium. The Li/W intercalation ratios for the tungsten oxide films were in the range 0.15–0.53. Temperature dependent resistivity measurements were performed in the temperature range 77–300 K for samples at different lithium intercalation levels. It was found that the data are consistent with the variable range hopping model.
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| 13. |
- Berggren, Lars, et al.
(författare)
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Trade Unions, the Social Democratic Party and Labor Market Conflicts in Malmö, 1890–1910
- 2023
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Ingår i: Trade Union Activism in the Nordic Countries since 1900. - Cham : Springer International Publishing. - 2634-6567 .- 2634-6559. - 9783031089879 - 9783031089862 ; , s. 93-109
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Bokkapitel (refereegranskat)abstract
- According to labor movement historian Axel Uhlén, two local conflicts in Malmö have created a huge interest all around Sweden (Uhlén, A. (1949) Facklig kamp i Malmö under sju decennier (Malmö: Framtiden), p. 259). The first labor dispute is the woodworker’s strike in 1890, called the Malmö revolt when thousands of people demonstrated in the streets and squares in the city center. Both local police and military forces encountered the demonstrators. The other one is a strike among municipal workers in 1908.
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| 14. |
- Berggren, Mats, et al.
(författare)
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Kärnkraftsdebatt ger möjlighet till kritiskt tänkande i högstadiefysiken
- 2019
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Ingår i: Naturvetenskapernas och teknikens didaktik. - Linköping : LiU-Tryck. - 9789176850442 ; , s. 39-48
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- I skolans styrdokument betonas vikten av att elever ges möjlighet att utveckla sitt kritiska tänkande. Detta är inte minst angeläget i dessa tider av tillgång till sociala medier och spridande av så kallade alternativa fakta. Trots sin positiva klang finns det dock ingen etablerad konsensus kring vad kritiskt tänkande egentligen är. Inom ramen för ett skolutvecklingsprojekt i samverkan mellan Uppsala universitet och Tiundaskolan, en 4-9-skola i Uppsala, utforskar vi hur kritiskt tänkande kan uttryckas i undervisningspraktiken i ämnena svenska, historia, matematik och fysik. Som exempel har vi i fysikämnet designat, genomfört och analyserat en undervisningssekvens utifrån kärnkraft som tema, där elever i årskurs 9 gavs möjlighet att anamma olika åsikter och argument i frågan genom rollspel. Eleverna genomförde en debatt, där de representerade olika parter: boende nära Forsmark, miljöorganisationen Grön Fred, och företag som utvecklar kärnkraft, respektive vindkraft. Före och efter debatten skrev eleverna individuella texter där de argumenterade för sin personliga åsikt i frågan: Ska kärnkraften bevaras som den är, läggas ner, eller utvecklas? Vi fann att de genom debatten fick goda möjligheter att utveckla och visa kunskaper motsvarande flera kunskapskrav i kursplanen i fysik som annars sällan berörs i fysikklassrummet, såsom, för betyg A: ”Eleven kan samtala om och diskutera frågor som rör energi, teknik, miljö och samhälle och skiljer då fakta från värderingar och formulerar ställningstaganden med välutvecklade motiveringar samt beskriver några tänkbara konsekvenser.” Som exempel på naturvetenskapligt förankrade argument utnyttjade eleverna genererad energi per utsläppt mängd koldioxid som ett mått vid jämförelser mellan kärnkraft och andra energikällor. I de individuella texterna höll de flesta eleverna fast vid sina åsikter från innan de arbetade med temat även efteråt, men nu med fler och mer nyanserade argument.
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| 15. |
- Bernabé, S., et al.
(författare)
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Highly integrated VCSEL-based 10Gb/s miniature optical sub-assembly
- 2005
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Ingår i: Proceedings - Electronic Components and Technology Conference. - Lake Buena Vista, FL : IEEE. ; , s. 1333-1338
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Konferensbidrag (refereegranskat)abstract
- In order to fit with the present and future needs of the Datacom transceiver market, newly designed high rate transmitter optical subassemblies (TOSAs) have to be compact, low cost and compatible with mass production. We propose here an innovative design strategy that reaches all these targets by integrating a 10Gbps 850nmVCSEL laser diode and its laser driver with other functionalities (e.g. power monitoring and thermal monitoring) in a small form factor package. Taking advantages of the optical properties of the VCSEL and using flip-chip techniques, the transmitter exhibits excellent hyperfrequency performances and compatibility with mass production due to the use of collective manufacturing technologies and passive optical alignment. This versatile approach is also applicable to high rate receivers, parallel optics emitters, and singlemode low cost transmitter integrating long wavelength VCSELs.
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| 16. |
- Brooke, Robert, et al.
(författare)
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Controlling the electrochromic properties of conductive polymers using UV-light
- 2018
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 6:17, s. 4663-4670
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Tidskriftsartikel (refereegranskat)abstract
- The phenomenon of electrochromism in conductive polymers is well known and has been exploited in many scientific reports. Using a newly developed patterning technique for conductive polymers, we manufactured high-resolution electrochromic devices from the complementary polymers PEDOT and polypyrrole. The technique, which combines UV-light exposure with vapor phase polymerization, has previously only been demonstrated with the conductive polymer PEDOT. We further demonstrated how the same technique can be used to control the optical properties and the electrochromic contrast in these polymers. Oxidant exposure to UV-light prior to vapor phase polymerization showed a reduction in polymer electrochromic contrast allowing high-resolution (100 mu m) patterns to completely disappear while applying a voltage bias due to their optical similarity in one redox state and dissimilarity in the other. This unique electrochromic property enabled us to construct devices displaying images that appear and disappear with the change in applied voltage. Finally, a modification of the electrochromic device architecture permitted a dual image electrochromic device incorporating patterned PEDOT and patterned polypyrrole on the same electrode, allowing the switching between two different images.
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| 17. |
- Brooke, Robert, 1989-, et al.
(författare)
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Greyscale and paper electrochromic polymer displays by UV patterning
- 2019
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 11:2
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Tidskriftsartikel (refereegranskat)abstract
- Electrochromic devices have important implications as smart windows for energy efficient buildings, internet of things devices, and in low-cost advertising applications. While inorganics have so far dominated the market, organic conductive polymers possess certain advantages such as high throughput and low temperature processing, faster switching, and superior optical memory. Here, we present organic electrochromic devices that can switch between two high-resolution images, based on UV-patterning and vapor phase polymerization of poly(3,4- ethylenedioxythiophene) films. We demonstrate that this technique can provide switchable greyscale images through the spatial control of a UV-light dose. The color space was able to be further altered via optimization of the oxidant concentration. Finally, we utilized a UV-patterning technique to produce functional paper with electrochromic patterns deposited on porous paper, allowing for environmentally friendly electrochromic displays.
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| 18. |
- Brooke, Robert, 1989-, et al.
(författare)
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Nanocellulose and PEDOT:PSS composites and their applications
- 2023
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Ingår i: Polymer Reviews. - : Taylor and Francis Ltd.. - 1558-3724 .- 1558-3716. ; :2, s. 437-
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Tidskriftsartikel (refereegranskat)abstract
- The need for achieving sustainable technologies has encouraged research on renewable and biodegradable materials for novel products that are clean, green, and environmentally friendly. Nanocellulose (NC) has many attractive properties such as high mechanical strength and flexibility, large specific surface area, in addition to possessing good wet stability and resistance to tough chemical environments. NC has also been shown to easily integrate with other materials to form composites. By combining it with conductive and electroactive materials, many of the advantageous properties of NC can be transferred to the resulting composites. Conductive polymers, in particular poly(3,4-ethylenedioxythiophene:poly(styrene sulfonate) (PEDOT:PSS), have been successfully combined with cellulose derivatives where suspensions of NC particles and colloids of PEDOT:PSS are made to interact at a molecular level. Alternatively, different polymerization techniques have been used to coat the cellulose fibrils. When processed in liquid form, the resulting mixture can be used as a conductive ink. This review outlines the preparation of NC/PEDOT:PSS composites and their fabrication in the form of electronic nanopapers, filaments, and conductive aerogels. We also discuss the molecular interaction between NC and PEDOT:PSS and the factors that affect the bonding properties. Finally, we address their potential applications in energy storage and harvesting, sensors, actuators, and bioelectronics. © 2022 The Author(s).
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| 19. |
- Brooke, Robert, 1989-, et al.
(författare)
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Supercapacitors on demand : All-printed energy storage devices with adaptable design
- 2019
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Ingår i: Flexible and Printed Electronics. - : Institute of Physics Publishing. - 2058-8585. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Demands on the storage of energy have increased for many reasons, in part driven by household photovoltaics, electric grid balancing, along with portable and wearable electronics. These are fast-growing and differentiated applications that need large volume and/or highly distributed electrical energy storage, which then requires environmentally friendly, scalable and flexible materials and manufacturing techniques. However, the limitations on current inorganic technologies have driven research efforts to explore organic and carbon-based alternatives. Here, we report a conducting polymer:cellulose composite that serves as the active material in supercapacitors which has been incorporated into all-printed energy storage devices. These devices exhibit a specific capacitance of ≈90 F g -1 and an excellent cyclability (>10 000 cycles). Further, a design concept coined 'supercapacitors on demand' is presented, which is based on a printing-cutting-folding procedure, that provides us with a flexible production protocol to manufacture supercapacitors with adaptable configuration and electrical characteristics.
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| 20. |
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| 21. |
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| 22. |
- Chacinski, Marek, et al.
(författare)
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Dynamic properties of electrically p-n confined, epitaxially regrown 1.27 μm InGaAs single-mode vertical-cavity surface-emitting lasers
- 2009
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Ingår i: IET optoelectronics. - : Institution of Engineering and Technology (IET). - 1751-8768 .- 1751-8776. ; 3:3, s. 163-167
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic performance including chirp measurements of 1.27 mu m single-mode InGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) with a large gain-cavity offset is presented. The VCSELs are based on a novel p-n confinement structure with selective area epitaxial regrowth. A resonance frequency of 9.11 GHz, a slope efficiency of 0.25 W/A and an alpha-factor of 5.7 were measured. The modulation bandwidth is limited by electrical parasitics. Eye diagrams at 5 Gb/s with 7 dB extinction ratio and Q-factor around 5 were obtained. The results are compared with the performance of oxide-confined VCSELs with similar active layer and negative gain-cavity detuning.
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| 23. |
- Chacinski, Marek, et al.
(författare)
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Single-mode 1.27 μm InGaAs vertical cavity surface-emitting lasers with temperature-tolerant modulation characteristics
- 2005
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:21, s. 211109-1-211109-3
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic performance of InGaAs/GaAs 1.27 μ m single-mode vertical cavity surface emitting lasers (VCSELs) is presented. In order to reach such a long wavelength, the devices utilize highly strained double-quantum wells and a large detuning between the material gain peak and cavity resonance. It is found that the large detuning improves the temperature stability of both static and modulation characteristics. A resonance frequency of 7.8-9.5 GHz and optical power of 0.30 mW in fiber was maintained throughout the investigated temperature range of 20-90 ° C. The intrinsic response of the device suggests that long-wavelength InGaAs/GaAs VCSELs have the potential to be used as low cost uncooled optical transmitters at 10 Gbit/s. © 2005 American Institute of Physics. © 2005 American Institute of Physics.
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| 24. |
- Chang, Tzu-Hsuan, et al.
(författare)
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Selective release of InP heterostructures from InP substrates
- 2016
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Ingår i: Journal of Vacuum Science & Technology B. - : American Institute of Physics (AIP). - 1071-1023 .- 1520-8567. ; 34:4
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Tidskriftsartikel (refereegranskat)abstract
- The authors report here a method of protecting the sidewall for the selective release of InGaAsP quantum-well (QW) heterostructure from InP substrates. An intact sidewall secured by SiO2 was demonstrated during the sacrificial layer selective etching, resulting in the suspended InGaAsP QW membranes which were later transferred to the Si substrate with polydimethylsiloxane stamp. The quality of the transferred InGaAsP QW membranes has been validated through photoluminescence and EL measurements. This approach could extend to arbitrary targeting substrate in numerous photonics and electronics applications.
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| 25. |
- Chen, Shangzhi, et al.
(författare)
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Redox-tunable structural colour images by UV-patterned conducting polymer nanofilms on metal surfaces
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Precise manipulation of light-matter interaction has enabled a wide variety of approaches to create bright and vivid structural colours. Techniques utilizing photonic crystals, Fabry-Pérot cavities, plasmonics, or high-refractive index dielectric metasurfaces have been studied for applications ranging from optical coatings to reflective displays. However, complicated fabrication procedures for sub-wavelength nanostructures, limited active areas, and inherent absence of tunability of these approaches significantly impede their further development towards flexible, large-scale, and switchable devices compatible with facile and cost-effective production. Herein, we present a simple and efficient method to generate structural colours based on nanoscale conducting polymer films prepared on metallic surfaces via vapour phase polymerization and ultraviolet (UV) light patterning. Varying the UV dose enables synergistic control of both nanoscale film thickness and polymer permittivity, which generates controllable colours from violet to red. Together with greyscale photomasks this enables fabrication of high-resolution colour images using single exposure steps. We further demonstrate spatiotemporal tuning of the structurally coloured surfaces and images via electrochemical modulation of the polymer redox state. The simple structure, facile fabrication, wide colour gamut, and dynamic colour tuning make this concept competitive for future multi-functional and smart displays.
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| 26. |
- Chen, Shangzhi, et al.
(författare)
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Tunable Structural Color Images by UV-Patterned Conducting Polymer Nanofilms on Metal Surfaces.
- 2021
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 33:33
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Tidskriftsartikel (refereegranskat)abstract
- Precise manipulation of light-matter interactions has enabled a wide variety of approaches to create bright and vivid structural colors. Techniques utilizing photonic crystals, Fabry-Pérot cavities, plasmonics, or high-refractive-index dielectric metasurfaces have been studied for applications ranging from optical coatings to reflective displays. However, complicated fabrication procedures for sub-wavelength nanostructures, limited active areas, and inherent absence of tunability of these approaches impede their further development toward flexible, large-scale, and switchable devices compatible with facile and cost-effective production. Here, a novel method is presented to generate structural color images based on monochromic conducting polymer films prepared on metallic surfaces via vapor phase polymerization and ultraviolet (UV) light patterning. Varying the UV dose enables synergistic control of both nanoscale film thickness and polymer permittivity, which generates controllable structural colors from violet to red. Together with grayscale photomasks this enables facile fabrication of high-resolution structural color images. Dynamic tuning of colored surfaces and images via electrochemical modulation of the polymer redox state is further demonstrated. The simple structure, facile fabrication, wide color gamut, and dynamic color tuning make this concept competitive for applications like multifunctional displays.
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| 27. |
- Chuwongin, S., et al.
(författare)
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Nanomembrane transfer printing for MR-VCSELs on silicon
- 2012
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Ingår i: 2012 IEEE Photonics Conference, IPC 2012. - : IEEE. - 9781457707315 ; , s. 951-952
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Konferensbidrag (refereegranskat)abstract
- The creation of silicon based light sources has been a major research and development effort world-wide. Among various approaches to silicon based light sources reported thus far, the hybrid gain-medium approach (especially integrated with group III-V materials) seems to be the most promising one due to its higher efficiencies than any others. [1-3]
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| 28. |
- Dahl-Jensen, D., et al.
(författare)
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Eemian interglacial reconstructed from a Greenland folded ice core
- 2013
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 493:7433, s. 489-494
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Tidskriftsartikel (refereegranskat)abstract
- Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 +/- 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 +/- 250 metres, reaching surface elevations 122,000 years ago of 130 +/- 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.
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| 29. |
- Edberg, Jesper, et al.
(författare)
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Boosting the capacity of all-organic paper supercapacitors using wood derivatives
- 2018
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 6:1, s. 145-152
-
Tidskriftsartikel (refereegranskat)abstract
- Printed and flexible organic electronics is a steadily expanding field of research and applications. One of the most attractive features of this technology is the possibility of large area and high throughput production to form low-cost electronics on different flexible substrates. With an increasing demand for sustainable energy production, low-cost and large volume technologies to store high-quality energy become equally important. These devices should be environmentally friendly with respect to their entire life cycle. Supercapacitors and batteries based on paper hold great promise for such applications due to the low cost and abundance of cellulose and other forest-derived components. We report a thick-film paper-supercapacitor system based on cellulose nanofibrils, the mixed ion-electron conducting polymer PEDOT: PSS and sulfonated lignin. We demonstrate that the introduction of sulfonated lignin into the cellulose-conducting polymer system increases the specific capacitance from 110 to 230 F g(-1) and the areal capacitance from 160 mF cm(-2) to 1 F cm(-2). By introducing lignosulfonate also into the electrolyte solution, equilibrium, with respect to the concentration of the redox molecule, was established between the electrode and the electrolyte, thus allowing us to perform beyond 700 charge/discharge cycles with no observed decrease in performance.
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| 30. |
- Edberg, Jesper, et al.
(författare)
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Electrochemical circuits from 'cut and stick' PEDOT : PSS-nanocellulose composite
- 2017
-
Ingår i: Flexible and Printed Electronics. - : Institute of Physics Publishing (IOPP). - 2058-8585. ; 2:4
-
Tidskriftsartikel (refereegranskat)abstract
- We report a flexible self-standing adhesive composite made from PEDOT:PSS and nanofibrillated cellulose. The material exhibits good combined mechanical and electrical characteristics (an elastic modulus of 4.4 MPa, and an electrical conductivity of 30 S cm(-1)). The inherent self-adhesiveness of the material enables it to be laminated and delaminated repeatedly to form and reconfigure devices and circuits. This modular property opens the door for a plethora of applications where reconfigurability and ease-of-manufacturing are of prime importance. We also demonstrate a paper composite with ionic conductivity and combine the two materials to construct electrochemical devices, namely transistors, capacitors and diodes with high values of transconductance, charge storage capacity and current rectification. We have further used these devices to construct digital circuits such as NOT, NAND and NORlogic.
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| 31. |
- Edberg, Jesper, 1988-
(författare)
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Flexible and Cellulose-based Organic Electronics
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organic electronics is the study of organic materials with electronic functionality and the applications of such materials. In the 1970s, the discovery that polymers can be made electrically conductive led to an explosion within this field which has continued to grow year by year. One of the attractive features of organic electronic materials is their inherent mechanical flexibility, which has led to the development of numerous flexible electronics technologies such as organic light emitting diodes and solar cells on flexible substrates. The possibility to produce electronics on flexible substrates like plastic or paper has also had a large impact on the field of printed, electronics where inks with electronic functionality are used for large area fabrication of electronic devices using classical printing methods, such as screen printing, inkjet printing and flexography.Recently, there has been a growing interest in the use of cellulose in organic and printed electronics, not only as a paper substrate but also as a component in composite materials where the cellulose provides mechanical strength and favorable 3D-microstructures. Nanofibrillated cellulose is composed of cellulose fibers with high aspect-ratio and diameters in the nanometer range. Due to its remarkable mechanical strength, large area-to-volume ratio, optical transparency and solution processability it has been widely used as a scaffold or binder for electronically active materials in applications such as batteries, supercapacitors and optoelectronics.The focus of this thesis is on flexible devices based on conductive polymers and can be divided into two parts: (1) Composite materials of nanofibrillated cellulose and the conductive polymer PEDOT:PSS and (2) patterning of vapor phase polymerized conductive polymers. In the first part, it is demonstrated how the combination of cellulose and conductive polymers can be used to make electronic materials of various form factors and functionality. Thick, freestanding and flexible “papers” are used to realize electrochemical devices such as transistors and supercapacitors while lightweight, porous and elastic aerogels are used for sensor applications. The second focus of the thesis is on a novel method of patterning conductive polymers produced by vapor phase polymerization using UV-light. This method is used to realize flexible electrochromic smart windows with high-resolution images and tunable optical contrast.
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| 32. |
- Edberg, Jesper, et al.
(författare)
-
Improving the Performance of Paper Supercapacitors Using Redox Molecules from Plants
- 2019
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Ingår i: ADVANCED SUSTAINABLE SYSTEMS. - : WILEY-V C H VERLAG GMBH. - 2366-7486. ; 3:8
-
Tidskriftsartikel (refereegranskat)abstract
- A supercapacitor made from organic and nature-based materials, such as conductive polymers (PEDOT:PSS), nanocellulose, and an the organic dye molecule (alizarin), is demonstrated. The dye molecule, which historically was extracted from the roots of the plant rubia tinctorum, is here responsible for the improvement in energy storage capacity, while the conductive polymer provides bulk charge transport within the composite electrode. The forest-based nanocellulose component provides a mechanically strong and nonporous network onto which the conductive polymer self-organizes. The electrical and electrochemical properties of the material composition are investigated and prototype redox-enhanced supercapacitor devices with excellent specific capacitance exceeding 400 F g(-1) and an operational stability over >1000 cycles are demonstrated. This new class of supercapacitors, which in part are based on organic materials from plants, represents an important step toward a green and sustainable energy technology.
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| 33. |
- Edberg, Jesper, et al.
(författare)
-
Patterning and Conductivity Modulation of Conductive Polymers by UV Light Exposure
- 2016
-
Ingår i: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-301X .- 1616-3028. ; 26:38, s. 6950-6960
-
Tidskriftsartikel (refereegranskat)abstract
- A novel patterning technique of conductive polymers produced by vapor phase polymerization is demonstrated. The method involves exposing an oxidant film to UV light which changes the local chemical environment of the oxidant and subsequently the polymerization kinetics. This procedure is used to control the conductivity in the conjugated polymer poly(3,4-ethylenedioxythiophene): tosylate by more than six orders of magnitude in addition to producing high-resolution patterns and optical gradients. The mechanism behind the modulation in the polymerization kinetics by UV light irradiation as well as the properties of the resulting polymer are investigated.
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| 34. |
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| 35. |
- Elfström, Magnus, 1971-, et al.
(författare)
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Temperamental and behavioural characteristics of adults seeking treatment for severe dental fear
- 2009
-
Ingår i: Psychology and Health. - : Informa UK Limited. - 0887-0446 .- 1476-8321. ; 24:sup. 1, s. 162-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Other psychological/behavioral factors in addition to fear and traditional measures of psychopathology should possibly be considered in the assessment and treatment of dental fear. The present study investigated fear and personality profiles among severely fearful adult patients. Participants were 230 consecutive adults applying for treatment of severe dental anxiety at a specialized clinic. Background data included dental treatment and dental fear history, general anxiety and depression assessments. Cluster analyses were performed. Four different fear and personality subgroups were judged to best represent data: (I) Fearful, extrovert, outgoing, (II) Highly fearful, extrovert, outgoing, (III) Fearful, inhibited, and (IV) Highly fearful, multiple problems. The view that adults with dental fear comprise a heterogeneous group was strengthened. Apart from different levels of dental fear, there seems to be varying temperamental and behavioral characteristics that need to be further studied and that may lead to a better match of treatment for these patients.
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| 36. |
- Eliasson, Lena, et al.
(författare)
-
PKC-dependent stimulation of exocytosis by sulfonylureas in pancreatic beta cells
- 1996
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 271:5250, s. 813-815
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Tidskriftsartikel (refereegranskat)abstract
- Hypoglycemic sulfonylureas represent a group of clinically useful antidiabetic compounds that stimulate insulin secretion from pancreatic beta cells. The molecular mechanisms involved are not fully understood but are believed to involve inhibition of potassium channels sensitive to adenosine triphosphate (KATP channels) in the beta cell membrane, causing membrane depolarization, calcium influx, and activation of the secretory machinery. In addition to these effects, sulfonylureas also promoted exocytosis by direct interaction with the secretory machinery not involving closure of the plasma membrane KATP channels. This effect was dependent on protein kinase C (PKC) and was observed at therapeutic concentrations of sulfonylureas, which suggests that it contributes to their hypoglycemic action in diabetics.
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| 37. |
- Eliasson, Lena, et al.
(författare)
-
SUR1 Regulates PKA-independent cAMP-induced Granule Priming in Mouse Pancreatic B-cells.
- 2003
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Ingår i: Journal of General Physiology. - : Rockefeller University Press. - 0022-1295 .- 1540-7748. ; 121:3, s. 181-197
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of membrane capacitance were applied to dissect the cellular mechanisms underlying PKA-dependent and -independent stimulation of insulin secretion by cyclic AMP. Whereas the PKA-independent (Rp-cAMPS–insensitive) component correlated with a rapid increase in membrane capacitance of ~80 fF that plateaued within ~200 ms, the PKA-dependent component became prominent during depolarizations >450 ms. The PKA-dependent and -independent components of cAMP-stimulated exocytosis differed with regard to cAMP concentration dependence; the Kd values were 6 and 29 µM for the PKA-dependent and -independent mechanisms, respectively. The ability of cAMP to elicit exocytosis independently of PKA activation was mimicked by the selective cAMP-GEFII agonist 8CPT-2Me-cAMP. Moreover, treatment of B-cells with antisense oligodeoxynucleotides against cAMP-GEFII resulted in partial (50%) suppression of PKA-independent exocytosis. Surprisingly, B-cells in islets isolated from SUR1-deficient mice (SUR1-/- mice) lacked the PKA-independent component of exocytosis. Measurements of insulin release in response to GLP-1 stimulation in isolated islets from SUR1-/- mice confirmed the complete loss of the PKA-independent component. This was not attributable to a reduced capacity of GLP-1 to elevate intracellular cAMP but instead associated with the inability of cAMP to stimulate influx of Cl- into the granules, a step important for granule priming. We conclude that the role of SUR1 in the B cell extends beyond being a subunit of the plasma membrane KATP-channel and that it also plays an unexpected but important role in the cAMP-dependent regulation of Ca2+-induced exocytosis.
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| 38. |
- Fan, W., et al.
(författare)
-
Electrically-pumped membrane-reflector surface-emitters on silicon
- 2013
-
Ingår i: 2013 IEEE Photonics Society Summer Topical Meeting Series, PSSTMS 2013. - : IEEE. - 9781467350600 ; , s. 19-20
-
Konferensbidrag (refereegranskat)abstract
- We report here electrically-pumped membrane reflector surface-emitters on silicon based on transferred InGaAsP QW structures sandwiched in between two single-layer Fano resonance photonic crystal membrane reflectors on silicon substrate.
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| 39. |
- Fan, W., et al.
(författare)
-
Fabrication of electrically-pumped resonance-cavity membrane-reflector surface-emitters on silicon
- 2013
-
Ingår i: 2013 IEEE Photonics Conference (IPC). - 9781457715075 ; , s. 643-644
-
Konferensbidrag (refereegranskat)abstract
- Various lasers and light sources on Si via heterogeneous integration of Si/III-V have been reported based on direct growth on Si [1] or wafer bonding technology [2-4]. We reported earlier optically-pumped Si membrane-reflector vertical-cavity surface-emitting lasers (MRVCSELs) fabricated by low-temperature membrane transfer printing processes [5, 6]. Here we report electrically-pumped devices based on an intra-cavity contact configuration.
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| 40. |
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| 41. |
- Gamage, Sampath, et al.
(författare)
-
Transparent nanocellulose metamaterial enables controlled optical diffusion and radiative cooling
- 2020
-
Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 8:34, s. 11687-11694
-
Tidskriftsartikel (refereegranskat)abstract
- Materials that provide independent control of infrared thermal radiation and haze in the visible could benefit many areas and applications, including clothing, packaging and photovoltaics. Here, we study this possibility for a metamaterial composite paper based on cellulose nanofibrils (CNF) and silicon dioxide (SiO2) microparticles with infrared (IR) Fröhlich phonon resonances. This CNF-SiO2composite shows outstanding transparency in the visible wavelength range, with the option of controlling light diffusion and haze from almost zero to 90% by varying the SiO2microparticle concentration. We further show that the transparent metamaterial paper could maintain high thermal emissivity in the atmospheric IR window, as attributed to strong IR absorption of both the nanocellulose and the resonant SiO2microparticles. The high IR emissivity and low visible absorption make the paper suitable for passive radiative cooling and we demonstrate cooling of the paper to around 3 °C below ambient air temperature by exposing it to the sky.
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| 42. |
- Gilet, Ph., et al.
(författare)
-
1.3 μm VCSELs : InGaAs/GaAs, GaInNAs/GaAs multiple quantum wells and InAs/GaAs quantum dots- Three candidates as active material
- 2007
-
Ingår i: Vertical - Cavity Surface - Emitting Lasers XI. - San Jose, CA : SPIE. ; , s. F4840-F4840
-
Konferensbidrag (refereegranskat)abstract
- In this article, we report our results on 1.3ÎŒm VCSELs for optical interconnection applications. Room temperature continuous-wave lasing operation is demonstrated for top emitting oxide-confined devices with three different active materials, highly strained InGaAs/GaAs(A) and GalnNAs/GaAs (B) multiple quantum wells (MQW) or InAs/GaAs (C) quantum dots (QD). Conventional epitaxial structures grown respectively by Metal Organic Vapour Phase Epitaxy (MOVPE), Molecular Beam Epitaxy (MBE) and MBE, contain rully doped GaAs/AlGaAs DBRs. All three epilayers are processed in the same way. Current and optical confinement are realized by selective wet oxidation. Circular apertures from 2 ÎŒm to 16 ÎŒm diameters are defined. At room temperature and in continuous wave operation, all three systems exhibit lasing operation at wavelengths above 1 275nm and reached 1 300nm for material (A). Typical threshold currents are in the range [1-10]mA and are strongly dependent firstly on oxide diameter and secondly on temperature. Room temperature cw maximum output power corresponds respectively to 1.77mW, 0.5mW and 0.6mW. By increasing driving current, multimode operation occurs at different level depending on the oxide diameter. In case (A), non conventional modal behaviors will be presented and explained by the presence of specific oxide modes. Thermal behaviors of the different devices have been compared. In case (A) and (C) we obtain a negative T0. We will conclude on the different active materials in terms of performances with respect to 1300nm VCSEL applications.
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| 43. |
-
Glänta
- 2021
-
Samlingsverk (redaktörskap) (populärvet., debatt m.m.)
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| 44. |
- Gromada, Jesper, et al.
(författare)
-
Neuronal calcium sensor-1 potentiates glucose-dependent exocytosis in pancreatic beta cells through activation of phosphatidylinositol 4-kinase beta
- 2005
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 102:29, s. 10303-8
-
Tidskriftsartikel (refereegranskat)abstract
- Cytosolic free Ca2+ plays an important role in the molecular mechanisms leading to regulated insulin secretion by the pancreatic beta cell. A number of Ca2+-binding proteins have been implicated in this process. Here, we define the role of the Ca2+-binding protein neuronal Ca2+ sensor-1 (NCS-1) in insulin secretion. In pancreatic beta cells, NCS-1 increases exocytosis by promoting the priming of secretory granules for release and increasing the number of granules residing in the readily releasable pool. The effect of NCS-1 on exocytosis is mediated through an increase in phosphatidylinositol (PI) 4-kinase beta activity and the generation of phosphoinositides, specifically PI 4-phosphate and PI 4,5-bisphosphate. In turn, PI 4,5-bisphosphate controls exocytosis through the Ca2+-dependent activator protein for secretion present in beta cells. Our results provide evidence for an essential role of phosphoinositide synthesis in the regulation of glucose-induced insulin secretion by the pancreatic beta cell. We also demonstrate that NCS-1 and its downstream target, PI 4-kinase beta, are critical players in this process by virtue of their capacity to regulate the release competence of the secretory granules.
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| 45. |
- Gustafsson, Oscar, et al.
(författare)
-
Long-wavelength infrared photoluminescence from InGaSb/InAs quantum dots
- 2013
-
Ingår i: Infrared physics & technology. - : Elsevier BV. - 1350-4495 .- 1879-0275. ; 59, s. 89-92
-
Tidskriftsartikel (refereegranskat)abstract
- We study the growth of self-assembled InGaSb/InAs quantum dots (QDs) and investigate how gallium can be used to reduce the optical transition energy in the InSb QD system. InGaSb QDs were grown on InAs (0 0 1) substrates by metal-organic vapor-phase epitaxy (MOVPE) and the material was characterized by photoluminescence (PL) measurements. A PL peak wavelength is demonstrated beyond 8 μm at 77 K, which is significantly longer than what has been reported for InSb QDs. The results suggest that InGaSb QDs can be grown at a larger size than InSb QDs leading to reduced confinement in the QDs.
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| 46. |
- Gustafsson, Oscar, et al.
(författare)
-
Long-wavelength infrared quantum-dot based interband photodetectors
- 2011
-
Ingår i: Infrared physics & technology. - : Elsevier BV. - 1350-4495 .- 1879-0275. ; 54:3, s. 287-291
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the design and fabrication of (Al)GaAs(Sb)/InAs tensile strained quantum-dot (QD) based detector material for thermal infrared imaging applications in the long-wavelength infrared (LWIR) regime. The detection is based on transitions between confined dot states and continuum states in a type-II band lineup, and we therefore refer to it as a dot-to-bulk (D2B) infrared photodetector with expected benefits including long carrier lifetime due to the type-II band alignment, suppressed Shockley-Read-Hall generation-recombination due to the relatively large-bandgap matrix material, inhibited Auger recombination processes due to the tensile strain and epitaxial simplicity. Metal-organic vapor-phase epitaxy was used to grow multiple (Al)GaAs(Sb) QD layers on InAs substrates at different QD nominal thicknesses, compositions, doping conditions and multilayer periods, and the material was characterized using atomic force and transmission electron microscopy, and Fourier-transform infrared absorption spectroscopy. Dot densities up to 1 x 10(11) cm(-2), 1 x 10(12) cm(-2) and 3 x 10(10) cm(-2) were measured for GaAs, AlGaAs and GaAsSb QDs, respectively. Strong absorption in GaAs, AlGaAs and GaAsSb multilayer QD samples was observed in the wavelength range 6-12 mu m. From the wavelength shift in the spectral absorption for samples with varying QD thickness and composition it is believed that the absorption is due to an intra- valance band transition. From this it is possible to estimate the type-II inter-band transition wavelength, thereby suggesting that (Al)GaAs(Sb) QD/InAs heterostructures are suitable candidates for LWIR detection and imaging.
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| 47. |
- Gustafsson, Oscar, et al.
(författare)
-
Photoluminescence photoresponse from InSb/InAs-based quantum dot structures
- 2012
-
Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 20:19, s. 21264-71
-
Tidskriftsartikel (refereegranskat)abstract
- InSb-based quantum dots grown by metal-organic vapor-phase epitaxy (MOVPE) on InAs substrates are studied for use as the active material in interband photon detectors. Long-wavelength infrared (LWIR) photoluminescence is demonstrated with peak emission at 8.5 μm and photoresponse, interpreted to originate from type-II interband transitions in a p-i-n photodiode, was measured up to 6 μm, both at 80 K. The possibilities and benefits of operation in the LWIR range (8-12 μm) are discussed and the results suggest that InSb-based quantum dot structures can be suitable candidates for photon detection in the LWIR regime.
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| 48. |
- Hammar, Mattias, et al.
(författare)
-
1.3-mu m InGaAs vertical-cavity surface-emitting lasers
- 2005
-
Ingår i: 2005 IEEE LEOS Annual Meeting Conference Proceedings (LEOS). - 0780392175 ; , s. 396-397
-
Konferensbidrag (refereegranskat)abstract
- We report on the fabrication and performance of N-free InGaAs/GaAs 1.3-mu m range vertical-cavity surface-emitting lasers (VCSELs). Using optimized quantum-well (QW) growth conditions in combination with negative gain-cavity tuning, high-performance VCSELs with emission wavelength up to 1300 nm are realized. The performance figures include mA-range threshold currents, mW-range singlemode output power, continuous-wave operation up to 140 degrees C and 10 Gbit/s data transmission.
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| 49. |
- Hammar, Mattias, et al.
(författare)
-
Room-temperature operation of 980-nm transistor-vertical-cavity surface-emitting lasers
- 2013
-
Ingår i: 2013 IEEE 6th International Conference on Advanced Infocomm Technology, ICAIT 2013. - : IEEE. - 9781479904655 ; , s. 141-142
-
Konferensbidrag (refereegranskat)abstract
- We report on the design, fabrication and characterization of pnp-type 980-nm transistor-vertical-cavity surface-emitting lasers (T-VCSELs). Using an epitaxial regrowth process and a triple-intracavity current injection scheme we demonstrate static performance levels quite comparable to those of conventional VCSELs, including sub-mA threshold base current, mW-range output power and continuous-wave operation at least up to 50°C.
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| 50. |
- Hägglin, Catharina, 1955, et al.
(författare)
-
A Swedish version of the GOHAI index. Psychometric properties and validation.
- 2005
-
Ingår i: Swedish dental journal. - 0347-9994. ; 29:3, s. 113-24
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigated a Swedish version of the 12 item General Oral Health Assessment Index (GOHAI). The aim was to validate the translated instrument, and to investigate factors that may influence the GOHAI score. Consecutive samples at eight dental clinics in Göteborg, Sweden were asked to answer the GOHAI, the short form of Oral Health Impact Profile (OHIP-14) and a questionnaire including socio-demographic, general health and oral health questions. 153 patients (50-89 yrs old) out of 237 (65%) returned the questionnaires. The most commonly reported problem (GOHAI) was 'worried or concerned' due to problems related to oral health (48%), followed by 'unhappy with the appearance of teeth, gums, or dentures' (36%) and 'teeth sensitive to hot, cold, or sweets' (33%). The Cronbach's Alpha (0.86) indicated a high degree of internal consistency and homogeneity between items. Item-scale correlations varied between 0.50 and 0.83. Strong relations were found between depressed GOHAI-scores and dental problems (mobile teeth, number of teeth, dentures). The correlation between the GOHAI score and the OHIP-14 was high (-0.83) indicating good construct validity. Also 'perceived general health' and 'satisfaction with life-situation' and dental status were significantly, but less strongly, correlated with the patient's GOHAI score. In a linear regression analysis, age,'perceived general health' and dental status (number of teeth in lower jaw and mobile teeth) were found to have a significant effect on the GOHAI score. Factor analysis of GOHAI indicated a two-factor solution and did not support the theoretical construction reported of the index. The test-re-test reliability was assessed in a separate sample (members of a physical handicap organization, n = 47) and the correlation coefficient for the GOHAI was 0.64. For individual items, the weighted kappa coefficient varied between 0.25 and 0.80. In conclusion, the Swedish version of the GOHAI showed acceptable reliability and validity.
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