| 1. |
- Achtziger, N, et al.
(författare)
-
Hydrogen passivation of silicon carbide by low-energy ion implantation
- 1998
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 73, s. 945-947
-
Tidskriftsartikel (refereegranskat)abstract
- implantation of deuterium is performed to investigate the mobility and passivating effect of hydrogen in epitaxial alpha-SiC (polytypes 4H and 6H). To avoid excessive damage and the resulting trapping of hydrogen, the implantation is performed with low energy (600 eV H-2(2)+). The H-2 depth profile is analyzed by secondary ion mass spectrometry. Electrical properties are measured by capacitance-voltage profiling and admittance spectroscopy. In p-type SIG, hydrogen diffuses on a mu m scale even at room temperature and effectively passivates accepters. In n-type SiC, the incorporation of H is suppressed and no passivation is detected. (C) 1998 American Institute of Physics.
|
|
| 2. |
- Achtziger, N, et al.
(författare)
-
Mobility passivating effect and thermal stability of hydrogen in silicon carbide
- 1998
-
Ingår i: Physica status solidi. B, Basic research. - 0370-1972 .- 1521-3951. ; 210, s. 395-399
-
Tidskriftsartikel (refereegranskat)abstract
- The diffusion and passivating effect of hydrogen (isotope H-2) in epitaxial p-type SiC is studied by secondary ion mass spectrometry and capacitance-voltage profiling on Schottky diodes. The incorporation of hydrogen is achieved by low-energy ion implantation. The influence of implantation energy, temperature and subsequent annealing is presented. Annealing experiments with an electric field applied reveal a reactivation of passivated accepters and a H+ ion drift at a surprisingly low temperature of 530 K.
|
|
| 3. |
- Janson, M., et al.
(författare)
-
Dissociation of deuterium-defect complexes in ion-implanted epitaxial 4H-SiC
- 1998
-
Ingår i: Materials Research Society Symposium - Proceedings. - San Francisco, CA, USA. ; , s. 439-444
-
Konferensbidrag (refereegranskat)abstract
- Epitaxial layers of low doped 4H-SiC are implanted with 20 keV 2H+ ions to a dose of 1×1015 cm-2. The samples are subsequently annealed at temperatures ranging from 1040 to 1135 °C. Secondary ion mass spectrometry is used to obtain the concentration versus depth profiles of the atomic deuterium in the samples. It is found that the concentration of implanted deuterium decreases rapidly in the samples as a function of anneal time. The experimental data are explained by a model where the deuterium migrates rapidly and becomes trapped and de-trapped at implantation-induced defects which exhibit a slightly shallower depth distribution than the implanted deuterium ions. Computer simulations using this model, in which the damage profile is taken from Monte Carlo simulations and the surface is treated as a perfect sink for the diffusing deuterium atoms, are performed with good results compared to the experimental data. The complexes are tentatively identified as carbon-deuterium at a Si-vacancy and a dissociation energy (ED) of approximately 4.9 eV is extracted for the deuterium-vacancy complexes.
|
|
| 4. |
|
|
| 5. |
- Linnarsson, M K, et al.
(författare)
-
Deuterium incorporation in acceptor doped epitaxial layers of 6H-SiC
- 1998
-
Ingår i: SILICON CARBIDE, III-NITRIDES AND RELATED MATERIALS, PTS 1 AND 2. ; , s. 761-764
-
Konferensbidrag (refereegranskat)abstract
- Deuterium is introduced in boron doped epitaxial layers of 6H-SiC by implantation of 30 keV H-2(+) ions in order to form a diffusion source. The samples were subsequently annealed in vacuum at 700 degrees C/16h, 800 degrees C/4h and 900 degrees C/4h. Using depth profiling by secondary ion mass spectrometry (SIMS), the distributions of deuterium at different levels of boron doping are studied. The deuterium concentration correlates with the boron concentration and at a level of similar to 10(18) cm(-3) a ratio H-2/B-11 larger than 0.5 is obtained. From capacitance-voltage (CV) measurements a decrease in the electrical carrier concentration by 50% is revealed after deuterium diffusion at 800 degrees C/4h. At 900 degrees C passivation of the boron accepters ceases but the H-2 atoms are still confined to the boron-doped regions and display no long range migration.
|
|
| 6. |
- Linnarsson, M K, et al.
(författare)
-
Diffusion of light elements in 4H-and 6H-SiC
- 1999
-
Ingår i: Materials Science & Engineering. - 0921-5107 .- 1873-4944. ; 61-2, s. 275-280
-
Tidskriftsartikel (refereegranskat)abstract
- Deuterium and lithium were introduced in p-type SiC by implantation of 20 keV H-2(+) or 30 keV Li-7(+) ions in order to form a diffusion source. The samples were subsequently annealed in vacuum in the temperature range 400-700 degrees C for 0.25 to 16 h. Secondary ion mass spectrometry (SIMS) was used to measure the deuterium and the lithium distribution after heat treatments. Both deuterium and lithium readily decorate the bombardment-induced defects in the vicinity of the ion implantation profile and they are also trapped, most likely by residual boron impurities, during diffusion into the bulk. An effective diffusion coefficient, reflecting the dissociation of trapped lithium, with an activation energy of 2.1 eV is extracted for lithium diffusion in p-type 6H SIG. Furthermore, a capture radius for trapping (most likely by boron) of deuterium is estimated as 10 Angstrom. (C) 1999 Elsevier Science S.A. All rights reserved.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
- Ivarsson, Karin, 1970, et al.
(författare)
-
The chemotactic cytokine interleukin-8--a cyst fluid marker for malignant epithelial ovarian cancer?
- 1998
-
Ingår i: Gynecologic oncology. - : Elsevier BV. - 0090-8258. ; 71:3, s. 420-3
-
Tidskriftsartikel (refereegranskat)abstract
- Due to the difficulties in separating malignant and benign ovarian cysts by transvaginal ultrasound and other techniques, there is a need for biochemical markers in serum or cyst fluids. In the present study we have evaluated the levels of the chemokine interleukin-8 (IL-8) in ovarian cysts. IL-8 is known to be expressed in the normal ovary and to influence proliferation and angiogenesis of several nonovarian types of tumors. Cyst fluids from benign (n = 15) and malignant (n = 13) ovarian tumors were analyzed. The levels of IL-8 were found to be significantly (13-fold) higher in cyst fluids from malignant tumors (18.1 +/- 7.5 ng/ml; mean +/- SE) compared to benign cysts (1.3 +/- 0.7 ng/ml). The plasma levels of IL-8 were considerably lower (2.9 and 0.3% of levels in benign and malignant cyst fluids, respectively) than in cyst fluids. No difference in the plasma levels of patients with benign or malignant tumor could be detected. In contrast, the levels of CA 125 were significantly higher in plasma of patients with malignant disease with the inverse relation in cyst fluids. In conclusion, the levels of IL-8 are markedly elevated in cyst fluid from malignant tumors compared to benign. This specific increase indicates a role for this cytokine in ovarian tumor biology.
|
|
| 14. |
- J. Carlsson, J.-C. Janson and M. Sparrman
(författare)
-
Affinity Chromatography
- 1998
-
Ingår i: J.-C. Janson and L. Rydén, (eds.), Protein Purification, Principles, High Resolution Methods and Applications. - : John Wiley & Sons Inc., New York. ; , s. 375-443
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
| 15. |
|
|
| 16. |
|
|
| 17. |
- Janson, Per-Olof, 1940, et al.
(författare)
-
Acromegaly and Cushing's syndrome due to ectopic production of GHRH and ACTH by a thymic carcinoid tumour: in vitro responses to GHRH and GHRP-6.
- 1998
-
Ingår i: Clinical endocrinology. - 0300-0664. ; 48:2, s. 243-50
-
Tidskriftsartikel (refereegranskat)abstract
- A 50-year-old male presented with diabetes mellitus and Cushing's syndrome associated with a large mediastinal mass. The levels of serum cortisol were high (1500-1800 nmol/l) without diurnal variation. Plasma ACTH levels (200-250 ng/l) and urinary excretion of cortisol were also increased. The levels of these hormones did not change in response to stimulation with corticotrophin releasing hormone (CRH) or suppression with high doses of dexamethasone. The patient had an elevated baseline GH level (7.3 mU/l), and the levels of immunoreactive GH-releasing hormone (GHRH) in eight plasma samples were markedly increased (600-1500 ng/l). Circulating levels of IGF-1, chromogranin A and neuropeptide Y (NPY) were also increased. Computer-assisted tomography and octreotide scintigraphy revealed a large mediastinal tumour and metastases in the left supraclavicular fossa. During treatment with octreotide, the baseline GH level was decreased (to 4.4 mU/l), while the GH pulse height was unchanged. Surgical removal of most of the tumour tissue resulted in a further decrease in the baseline serum GH level to a value (1.6 mU/l) about 20% of that before treatment, while the pulse height and mean GH were affected to a lesser extent. Postoperatively, circulating levels of cortisol and IGF-1 decreased, and the patient exhibited clinical improvement. Histological examination showed a neuroendocrine tumour with characteristics consistent with a foregut carcinoid of thymic origin. Immunoreactive GHRH, ACTH and NPY, but not immunoreactive GH, were detected in 80-90% of the tumour cells and the three peptides appeared to be co-localized. In primary culture, cells from this tumour displayed calcium influx in response to GHRH or GH releasing peptide-6 (GHRP-6), while there were not such responses by cells from another carcinoid not producing GHRH, ACTH or NPY. These results demonstrate a rare case of ectopic production of GHRH, ACTH and NPY, and indicate that the tumour cells were responsive to GHRH and GHRP-6 as well as octreotide.
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
- Stener-Victorin, Elisabet, 1964, et al.
(författare)
-
A prospective randomized study of electro-acupuncture versus alfentanil as anaesthesia during oocyte aspiration in in-vitro fertilization.
- 1999
-
Ingår i: Human reproduction (Oxford, England). - 0268-1161. ; 14:10, s. 2480-4
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to evaluate the anaesthetic effect during oocyte aspiration of a paracervical block (PCB) in combination with either electro-acupuncture (EA) or intravenous alfentanil. In all, 150 women undergoing in-vitro fertilization (IVF) and embryo transfer were randomized to receive either EA plus PCB or alfentanil plus PCB. Visual analogue scales (VAS) were used to evaluate subjective experiences during oocyte aspiration, and IVF outcome parameters were recorded. No differences in pain directly related to oocyte aspiration, adequacy of anaesthesia during oocyte aspiration, abdominal pain, or degree of nausea were found between the two groups in the VAS ratings. Before oocyte aspiration, the level of stress was significantly higher in the EA group than in the alfentanil group (P < 0.05), and the EA group experienced discomfort for a significantly longer period during oocyte aspiration (P < 0. 01). Compared with the alfentanil group, the EA group had a significantly higher implantation rate (P < 0.05), pregnancy rate (P < 0.05), and take home baby rate (P < 0.05) per embryo transfer. In conclusion, EA has been shown to be as good an anaesthetic method as alfentanil during oocyte aspiration, and we suggest that EA may be a good alternative to conventional anaesthesia during oocyte aspiration.
|
|
| 25. |
|
|
| 26. |
|
|
| 27. |
|
|
| 28. |
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
- von Euler, Mia, 1967-, et al.
(författare)
-
Quantitative study of neurofilament-positive fiber length in rat spinal cord lesions using isotropic virtual planes
- 1998
-
Ingår i: Journal of Comparative Neurology. - Philadelphia : John Wiley & Sons. - 0021-9967 .- 1096-9861. ; 400:4, s. 441-448
-
Tidskriftsartikel (refereegranskat)abstract
- Spontaneous reocurrence of neurofilament (NF)-positive fibers has been described after spinal cord lesions in rats. However, previously introduced methods to evaluate the lesion and the regenerative fiber outgrowth suffer from several biases, why a new concept of quantitative, morphological analysis after spinal cord injury is needed. Length quantification of the putatively spontaneously regenerating fibers has been difficult until recently, when two length estimators based on sampling with isotropic virtual planes within thick physical sections were introduced. The applicability of these techniques to estimate the total length of NF-positive fibers was evaluated in photochemically induced ischemic lesions of thoracic spinal cords in young rats 6 weeks postlesion. Fiber length was found to be the most consistent measure with a mean of 3.71 m (coefficient of variation, CV = 0.16) in the 0.90 mm3 (CV = 0.26) large lesions. Whether or not the NF-positive fibers observed inside the lesion represent spontaneously regenerating axons needs to be confirmed in longitudinal, functional, and ultrastructural studies.
|
|
| 32. |
- Zhao, Q, et al.
(författare)
-
Conjugate chemistry, iodination and cellular binding of mEGF-dextran-tyrosine: preclinical tests in preparation for clinicaltrials
- 1998
-
Ingår i: International Journal of Molecular Medicine. - : Spandidos Publications. - 1107-3756 .- 1791-244X. ; 1:4, s. 693-702
-
Tidskriftsartikel (refereegranskat)abstract
- A conjugate with specific binding to the epidermal growth factor receptor, EGFR, and of interest for clinical tests was prepared using mouse epidermal growth factor, mEGF, and dextran. The mEGF was first coupled to dextran by reductive amination in which the free amino group on the N-terminal of mEGF was reacted with the aldehyde group on the reductive end of the dextran chain. The end-end coupled intermediate was further activated by the cyanopyridinium agent CDAP and tyrosines introduced to the dextran part of the conjugate. The mEGF-dextran-tyrosine conjugate was, with high efficiency, iodinated with the chloramine-T method. Approximately 25-35% of the radioactivity could be removed from the conjugate after exposure to protease K while 65-75% of the radioactivity could be removed after exposure to dextranase. Thus, the largest amount of the iodine was on the dextran part of the conjugate. The iodinated mEGF-dextran-tyrosine had EGFR specific binding since the binding to an EGFR rich human glioma cell line could be displaced by an excess of non-radioactive mEGF. The conjugate was to a large extent internalized in these cells and the administrated radioactivity was thereby retained inside the cells for at least up to 50 h.
|
|
| 33. |
|
|
