| 1. |
- Haralson, Erik, et al.
(författare)
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Influence of self heating in a BiCMOS on SOI technology
- 2004
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Ingår i: ESSCIRC 2004. - NEW YORK : IEEE. - 0780384784 ; , s. 337-340
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Konferensbidrag (refereegranskat)abstract
- Self heating in a 0.25mum BiCMOS technology with different isolation structures is characterized. Thermal resistance values for single- and multiple-emitter devices are extracted and reported. The dependence of the thermal resistance on the emitter aspect ratio is critical to take into consideration when determining the isolation scheme for devices. 2-D electro-thermal simulations are performed and compared to experimental results. The impact of metallization on the self-heating in the device is examined through simulations.
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| 2. |
- Håkansson, Pär, et al.
(författare)
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Extended Förster theory for determining intraprotein distances : 1. The K2-dynamics and fluorophore reorientation
- 2004
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 108:44, s. 17243-17250
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Tidskriftsartikel (refereegranskat)abstract
- A detailed analysis of the previously developed (J. Chem. Phys. 1996, 105, 10896) extended Förster theory (EFT) is presented for analyzing electronic energy migration within pairs of donors (D). Synthetic data that mimics experimental time-correlated single photon counting data were generated and re-analyzed. To cover a wide dynamic range and various orientational restrictions, the rates of reorientation, as well as the orientational configurations of the interacting D-groups were varied. In general DD distances are recovered within an error limit of 5%, while the errors in orientational configurations are usually larger. The Maier−Saupe and cone potentials were used to generate an immense variety of orientational trajectories. The results obtained exhibit no significant dependence on the choice of potential function used for generating EFT data. Present work demonstrates how to overcome the classical “κ2-problem” and the frequently applied approximation of κ2 = 2/3 in the data analyses. This study also outlines the procedure for analyzing fluorescence depolarization data obtained for proteins, which are specifically labeled with D-groups. The EFT presented here brings the analyses of DDEM data to the same level of molecular detail as in ESR- and NMR-spectroscopy.
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| 3. |
- Isaksson, Mikael, et al.
(författare)
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An environmental-sensitive BODIPY®-derivative with bioapplication : spectral and photophysical properties
- 2003
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Ingår i: Journal of Fluorescence. - 1053-0509 .- 1573-4994. ; 13:5, s. 379-84
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Tidskriftsartikel (refereegranskat)abstract
- A previously synthesised derivative of BODIPY aimed for sulfhydryl specific labelling of cysteine residues in proteins was studied. The spectral and photophysical properties of this derivative, N-(4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene-2-yl) iodoacetamide (NBDY) were characterised, and found to be considerably different from those of commonly used derivatives of BODIPY, e.g. N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-yl)methyl iodoacetamide. The absorption and fluorescence spectra, as well as fluorescence lifetimes and quantum yields of NBDY are quite sensitive to solvent properties. The fluorescence is effectively quenched by I– when NBDY is free in water or attached to Cys in different mutants of plasminogen activator inhibitor type 2 (PAI-2). A ground-state dimer forms when two NBDY groups are closely spaced in plasminogen activator inhibitor type 1 (PAI-1).
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| 4. |
- Isaksson, Mikael, et al.
(författare)
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Partial donor-donor energy migration (PDDEM) : a novel fluorescence method for internal protein distance measurements
- 2004
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 6:11, s. 3001-3008
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Tidskriftsartikel (refereegranskat)abstract
- We show that the photophysics of chemically identical but photophysically non-identical fluorescent pairs can be used for measuring distances within proteins. For this purpose, the theory of partial donor-donor energy migration (PDDEM, S. Kalinin, J. G. Molotkovsky and L. B.-Angstrom. Johansson, Spectrochim. Acta, Part A, 2002, 58, 1057-1097) was applied for distance measurements between BODIPY groups covalently linked to cystein residues in plasminogen activator inhibitor of type 2 (PAI-2). Two sulfhydryl specific derivatives of BODIPY were used namely: N-(4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene-2-yl) iodoacetamide and N-(4.4-difluoro-5.7-ditriethyl-4-bona-3a,4a-diaza-s-indacene-3-yl) methyl iodoacetamide. To determine distances, the time-resolved fluorescence relaxation for two singly labelled forms of PAI-2, as well as the corresponding doubly labelled protein were combined and analysed in a global manner. Fluorescence depolarisation experiments on the labelled mutants were also analysed. The distances determined by PDDEM were in good agreement to those obtained from donor-donor energy migration (DDEM) experiments and structural data on PAI-2. The PDDEM approach allows for the use of very different fluorescent probes, which enables wide range of distances to be measured. The PDDEM model also provides a rational explanation to why previous observations of polyfluorophore-labelled proteins exhibit a shorter average fluorescence lifetime compared to the arithmetic average of lifetimes obtained for the corresponding single labelled proteins.
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| 5. |
- Malm, B. Gunnar, et al.
(författare)
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Implanted collector profile optimization in a SiGeHBT process
- 2001
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Ingår i: Solid-State Electronics. - 0038-1101 .- 1879-2405. ; 45:3, s. 399-404
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Tidskriftsartikel (refereegranskat)abstract
- Optimization of implanted collector doping profiles for a high-speed, low-voltage SiGe HBT process has been investigated experimentally and by device simulations. A low-energy antimony implantation has been combined with a standard selectively implanted collector using phosphorous, to achieve improved control of the collector doping profile. The simulations indicate that the narrow n-type doping peak formed by the antimony implantation allows the cut-off frequency f(T) to be increased without degrading the collector emitter breakdown voltage BVCEO. The fabricated devices demonstrate a highest f(T) of 60 GHz. Depending on the collector profile BVCEO values between 1.5 and 2 V were obtained.
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| 6. |
- Reikeras, O., et al.
(författare)
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Hydroxyapatite and carbon coatings for fixation of unloaded titanium implants
- 2004
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Ingår i: Journal of Long-Term Effects of Medical Implants. - 1050-6934 .- 1940-4379. ; 14:6, s. 443-454
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the interaction between bone and pure titanium, titanium coated with hydroxyapatite (HA), and titanium coated with carbon in a rat femur model. In 25 rats, the medullary cavity of both femurs was entered by an awl from the trochanteric area. With steel burrs it was successively reamed to a diameter of 2.0 mm. Nails with a diameter of 2.0 mm and with a length of 34 mm were inserted in a random manner; either a pure titanium nail, a titanium nail entirely plasma-sprayed with a 75-100-microm layer of HA or a titanium nail coated with 2-10-microm carbon. The surface roughness of the pure titanium was characterized by Ra 2.6 microm and Rt 22 microm. Ra of HA was 7.5 microm and Rt 52 microm, and of carbon Ra was 0.4 microm and Rt 4.0 microm. Twelve rats were randomized to a follow up of 8 weeks, and the remaining 13 rats were followed for 16 weeks. At sacrifice both femora were dissected free from soft tissues and then immersed in fixative. A specimen slice of about 5 mm thickness was prepared from the subtrochanteric region with a water-cooled band-saw. Sample preparation for un-decalcified tissue followed the internal guidelines at the laboratories of Biomaterials/Handicap Research. At 8 weeks the median bone bonding contact of the implants was 43% (range 0-74) in the titanium group, 39% (0-75) in the HA group, and 3% (0-59) in the carbon group. At 16 weeks the corresponding figures were 58% (0-78) in the titanium group, 51% (15-75) in the HA group, and 8% (0-79) in the carbon group. In conclusion, we found great variability in bone bonding contact. In general, carbon-coated nails had reduced bone bonding contact both at 8 and at 16 weeks as compared to pure titanium or titanium coated with hydroxyapatite.
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| 7. |
- Sundfeldt, Mikael, et al.
(författare)
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Long-term results of a cementless knee prosthesis with a metal-backed patellar component : clinical and radiological follow-up with histology from retrieved components
- 2003
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Ingår i: Journal of long-term effects of medical implants. - 1050-6934 .- 1940-4379. ; 13:4, s. 341-354
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Tidskriftsartikel (refereegranskat)abstract
- Aseptic loosening of cemented knee arthroplasties has encouraged development of uncemented fixation. The Miller-Galante I (MG I) prosthesis was designed to achieve permanent stability through ingrowth into a titanium fiber mesh. Thirty-five knees in 30 patients with MG I knee replacements have been followed clinically and radiologically with a mean follow-up of 12 years. Twenty knees were revised with a mean follow-up of 5 years. Patellofemoral problems, especially avulsion of the polyethylene from the metal-backed patella and in some cases severe metallosis, have been the main reason for revision. Metal-backed patellar component should be avoided. In addition, instability has been a problem. However, the fixation of the components has been excellent, with a high degree of osseous ingrowth displayed at histological analysis of retrieved components. The clinical and radiological results after revision are in most cases good, despite the femoral component having been left in situ.
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| 8. |
- Vestergren, Marcus, et al.
(författare)
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Synthesis, crystal structure, and chirality of divalent lanthanide reagents containing tri- and tetraglyme
- 2004
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Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 689:10, s. 1723-1733
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Tidskriftsartikel (refereegranskat)abstract
- Six new divalent lanthanide complexes using triglyme (trigly) and tetraglyme (tetgly) as achiral ligands have been prepared, using a facile synthetic method, in search for enantioselective solid-state reagents. The crystal structures of cis-[SmI2(trigly)thfl] (1), trans[YbI2(trigly)thf] (2), trans-[SMI2(trigly)dme] (3), trans-[YbI2(tetgly)] (4), trans-[EuI2(tetgly)thfl] (5), and [SM(tetgly)2][SMI3(tetgly)]I (6) have been determined. All complexes, except 5, are chiral. The 10-coordinate cation in 6 displays a helical chirality since the two tetraglyme ligands are wrapped around the samarium ion. Since trans-[YbI2(tetgly)] (4), which has a chiral arrangement of terminal methyl groups, crystallizes as a conglomerate, preferential crystallization and consequent enantioselective reduction of acetophenone was attempted, but resulted in racemic products, possibly on account of racemic twinning in 4. (C) 2004 Elsevier B.V. All rights reserved.
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