| 1. |
- Bryllert, Tomas, et al.
(författare)
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Vertical high-mobility wrap-gated InAs nanowire transistor
- 2006
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 27:5, s. 323-325
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, the authors demonstrate a vertical wrap-gated field-effect transistor based on InAs nanowires [Proc. DRC, 2005, p. 157]. The nanowires have a diameter of 80 nm and are grown using selective epitaxy; a matrix of typically 10 x 10 vertically standing wires is used as channel in the transistor. The authors measure current saturation at V-ds = 0.15 V (V-g = 0 V), and a high mobility, compared to the previous nanowire transistors, is deduced.
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| 2. |
- Bryllert, Tomas, et al.
(författare)
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Vertical wrap-gated nanowire transistors
- 2006
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Ingår i: Nanotechnology. - 0957-4484. ; 17:11, s. 227-230
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Tidskriftsartikel (refereegranskat)abstract
- We present a process for fabricating a field-effect transistor based on vertically standing InAs nanowires and demonstrate initial device characteristics. The wires are grown by chemical beam epitaxy at lithographically defined locations. Wrap gates are formed around the base of the wires through a number of deposition and etch steps. The fabrication is based on standard III - V processing and includes no random elements or single nanowire manipulation.
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| 3. |
- Pettersson, Håkan, et al.
(författare)
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Photocurrent spectroscopy on self-assembled InAs quantum dots embedded in InP
- 2005
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Ingår i: Microelectronics Journal. - Amsterdam : Elsevier. - 0026-2692. ; 36:3-6, s. 227-230
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we report on an overview of recent results from Fourier transform photocurrent (FTPC) measurements in the infrared spectral region on ensembles of self-assembled InAs quantum dots embedded in a matrix of InP. In interband PC, clear signals related to the dots are observed. Comparing the PC- and PL spectra, we observe that the fundamental transition is absent in the PC spectra, which we interpret in terms of Pauliblocking due to a filled electron ground state of the dots. Our results furthermore suggest that an Auger process is involved in forming the interband PC signal. In intersubband PC, peaks related to transitions from the dots' ground- and first excited states to the conduction band of the matrix are observed. Using a novel approach of combining FTPC with illumination from an additional external non-modulated light source, we have measured the spectral distribution of photoionization of excitons in quantum dots and found an exciton binding energy in good agreement with theoretical calculations.
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| 4. |
- Gaines, Hans, et al.
(författare)
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Six-week follow-up after HIV-1 exposure: a position statement from the Public Health Agency of Sweden and the Swedish Reference Group for Antiviral Therapy
- 2016
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Ingår i: Infectious Diseases. - : Informa UK Limited. - 2374-4235 .- 2374-4243. ; 48:2, s. 93-98
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Forskningsöversikt (refereegranskat)abstract
- In 2014 the Public Health Agency of Sweden and the Swedish Reference Group for Antiviral Therapy (RAV) conducted a review and analysis of the state of knowledge on the duration of follow-up after exposure to human immunodeficiency virus (HIV). Up until then a follow-up of 12 weeks after exposure had been recommended, but improved tests and new information on early diagnosis motivated a re-evaluation of the national recommendations by experts representing infectious diseases and microbiology, county medical officers, the RAV, the Public Health Agency, and other national authorities. Based on the current state of knowledge the Public Health Agency of Sweden and the RAV recommend, starting in April 2015, a follow-up period of 6 weeks after possible HIV-1 exposure, if HIV testing is performed using laboratory-based combination tests detecting both HIV antibody and antigen. If point-of-care rapid HIV tests are used, a follow-up period of 8 weeks is recommended, because currently available rapid tests have insufficient sensitivity for detection of HIV-1 antigen. A follow-up period of 12 weeks is recommended after a possible exposure for HIV-2, since presently used assays do not include HIV-2 antigens and only limited information is available on the development of HIV antibodies during early HIV-2 infection. If pre- or post-exposure prophylaxis is administered, the follow-up period is recommended to begin after completion of prophylaxis. Even if infection cannot be reliably excluded before the end of the recommended follow-up period, HIV testing should be performed at first contact for persons who seek such testing.
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| 5. |
- Hjort, Filip, 1991, et al.
(författare)
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Optical microprism cavities based on dislocation-free GaN
- 2020
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 117:23
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Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional growth of nanostructures can be used to reduce the threading dislocation density that degrades III-nitride laser performance. Here, nanowire-based hexagonal GaN microprisms with flat top and bottom c-facets are embedded between two dielectric distributed Bragg reflectors to create dislocation-free vertical optical cavities. The cavities are electron beam pumped, and the quality (Q) factor is deduced from the cavity-filtered yellow luminescence. The Q factor is similar to 500 for a 1000nm wide prism cavity and only similar to 60 for a 600nm wide cavity, showing the strong decrease in Q factor when diffraction losses become dominant. Measured Q factors are in good agreement with those obtained from quasi-3D finite element frequency-domain method and 3D beam propagation method simulations. Simulations further predict that a prism cavity with a 1000nm width will have a Q factor of around 2000 in the blue spectral regime, which would be the target regime for real devices. These results demonstrate the potential of GaN prisms as a scalable platform for realizing small footprint lasers with low threshold currents.
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| 6. |
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| 7. |
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| 8. |
- Löwendahl, Lars, 1940, et al.
(författare)
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Dicarboxylic acids produced by oxygen-alkali treatment of birch xylan
- 1975
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Ingår i: Acta Chem. Scand. B. ; 29:4, s. 526-527
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Tidskriftsartikel (refereegranskat)abstract
- C-(2-Hydroxyethyl)tartronic acid is predominant among the dicarboxylic acids and its formation in 12 % yield makes it a major product from xylan. The structure indicates that it is formed from terminal, oxidized xylose units by beta-elimination at C-4 and subsequent benzilic acid rearrangement. It is proposed that 2-ulosonic acid end-groups or ulosono-1,5-lactone end-groups, related in structure to ascorbic acid, are formed as precursors.
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| 9. |
- Löwendahl, Lars, 1940, et al.
(författare)
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Oxygen-alkali treatment of cellobiose
- 1975
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Ingår i: Acta Chem. Scand. B. ; 29:9, s. 975-980
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Tidskriftsartikel (refereegranskat)abstract
- C-(2,3-Dihydroxypropyl)tartronic acid is a major dicarboxylic acid formed during O2-NaOH and O2-NaHCO3 treatment of cellobiose. The observation that this acid is the main reaction product after alkali treatment ofascorbic acid in O2-free medium supports the conclusion that it is formed via an aglycon moiety related to ascorbic acid. Other dicarboxylic acids from cellobiose are oxalic, tartronic, deoxytetraric, C-(hydroxymethyl)tartronic, and succinic acids.The temperature, pH and additions of iron and cobalt salts strongly influence the product composition. The formation of aldobionic acids from cellobiose parallels the formationof aldonic acid end groups during oxygen bleaching of cellulose.
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| 10. |
- Löwendahl, Lars, 1940, et al.
(författare)
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Phenolic compounds in kraft black liquor
- 1978
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Ingår i: Svensk Papperstidning. ; 81:12, s. 392-396
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Tidskriftsartikel (refereegranskat)abstract
- The prominent phenolic compounds with one aromatic ring in kraft black liquor were analysed by a combination of liquid chromatography, gas chromatography and mass spectrometry. Extracted spruce meal was cooked both under mild, conventional conditions and under extremely severe conditions. In all, the analyzed phenolic compounds amounted to 0.6 kg per 100 kg of dry wood under conventional conditions. In addition to 2-methoxyphenol, vanillin and 4-hydroxy-3-methoxyacetophenone, several phenolic alcohols and carboxylic acids with the same aromatic substitution were isolated and identified. The yield of related 3,4- dihydroxyphenylsubstituted compounds increased under severe conditions.
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