| 1. |
- Grama, D, et al.
(author)
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Clinical characteristics, treatment and survival of pancreatic tumors causing hormonal syndromes
- 1992
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In: World Journal of Surgery. - 0364-2313 .- 1432-2323. ; 16:4, s. 632-639
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Journal article (peer-reviewed)abstract
- Eighty-five patients with endocrine pancreatic tumors associated with clinical syndromes of hormone excess were retrospectively analyzed regarding symptomatology, means of diagnosis, and results of surgical and medical treatment during follow-up of 3-18 years (median 8 years). The combination of angiography and computed tomography was most successful in pre-operative localization of both primary tumors and metastases. Surgery provided long term cure in 39 of 44 patients with benign islet cell lesions, the majority having insulinomas. Forty-one patients had malignant tumors, which at the time of diagnosis or operation were associated with liver and/or regional lymph gland metastases in 56% and 24%, respectively. Sixteen patients with metastatic disease and/or very large tumors were considered inoperable, 5 patients underwent palliative resection of their malignant tumors, while grossly radical tumor removal was accomplished in 20 patients. Long-term cure was achieved in 5 patients by excision of primary tumors and localized liver or lymph gland metastases. Half of the patients, particularly those with insulinoma, gastrinoma, or vipoma, showed response to streptozotocin, in combination with other cytostatics, for a median of 24 months or a response to interferon for a median of 10 months. The overall 5-year and 10-year survival among the patients with malignant islet cells tumors was 54% and 28%, respectively. Absence of liver metastases at time of operation/diagnosis, smaller size of the primary tumor, grossly radical tumor resection as well as response to medical therapy predicted the more favorable survival.
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| 2. |
- Grama, D, et al.
(author)
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Pancreatic tumors in multiple endocrine neoplasia type 1 : clinical presentation and surgical treatment
- 1992
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In: World Journal of Surgery. - 0364-2313 .- 1432-2323. ; 16:4, s. 611-618
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Journal article (peer-reviewed)abstract
- Among 33 patients with endocrine pancreatic tumors due to multiple endocrine neoplasia type 1 (MEN-1), 19 (58%) patients had hypergastrinemia, 7 (21%) patients had hyperinsulinism, and 7 (21%) patients had clinically non-functioning lesions. At least one gross tumor was found in all patients undergoing pancreatic surgery, including those with negative localization studies prior to operation. The patients also had additional macroscopic tumors as well as numerous microadenomas, and the lesions frequently were positive for immunostaining with multiple hormones, mainly pancreatic polypeptide, insulin, glucagon, and somatostatin. Duodenal endocrine lesions were found in 4 of 5 investigated patients and stained with gastrin and somatostatin antibodies. Distal, mainly subtotal pancreatic resection, was performed in 18 patients, eventually combined with caput tumor enucleation or duodenotomy, while a few patients underwent only tumor enucleation or a Whipple procedure. The long-term outcome of operation was most favorable in patients with hyperinsulinism; only 1 patient had clinical recurrence. Patients with hypergastrinemia experienced only transitory lowering of serum gastrin values after pancreatic surgery and 47% of them had or developed metastases. Such tumor spread was seen in 57% of the patients with non-functioning lesions. Nine patients died from progressive tumor disease during follow-up. Consistent with previous studies, we found that surgery is indicated in MEN-1 patients with hyperinsulinism even if a lesion is not visualized by radiology. In addition, these indications should be extended to also include patients with only biochemical markers of disease, including elevations of gastrin, as these indicate the presence of gross tumors.
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| 3. |
- Rahbi, R., et al.
(author)
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Neutralisation of group vi donors by hydrogen in gallium arsenide
- 1994
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In: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 91:3, s. 187-190
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Journal article (peer-reviewed)abstract
- The infrared absorption of GaAs:S and GaAs:Te samples partially neutralised by hydrogen show two local modes with very similar frequencies. These modes are comparable to the ones already reported in GaAs:Se. These results are interpreted by assuming that neutralisation takes place by the formation of a bond between a Ga atom first neighbour of the chalcogen and a H atom in an antibonding location. This assumption is strengthened by ab initio calculations that provide also frequencies of the right order of magnitude.
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| 4. |
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| 5. |
- Holbech, J. D., et al.
(author)
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H2* defect in crystalline silicon
- 1993
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 71:6, s. 875-878
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Journal article (peer-reviewed)abstract
- Detailed infrared studies have been carried out on proton- and deuteron-implanted Si. A dominant trigonal defect involving a pair of inequivalent hydrogen atoms has been identified, with local modes at 2061.5, 1838.3, 1599.1, and 817.2 cm-1. The structure, the local modes, and the isotopic shifts of the H2* defect have been calculated using ab initio pseudopotential cluster theory. The structure is consistent with channeling and uniaxial stress experiments. The calculated frequencies and isotopic shifts are in close agreement with those observed.
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| 6. |
- Jones, R, et al.
(author)
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Ab initio calculations of the structure and dynamics of C60 and C3- 60
- 1992
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In: Philosophical Magazine Letters. - : Informa UK Limited. - 0950-0839 .- 1362-3036. ; 65:6, s. 291-298
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Journal article (peer-reviewed)abstract
- A local-density-functional cluster method is used to calculate the structure and vibrational modes of C60. We find C–C lengths in good agreement with observed values. The effect of doping the molecule with three extra electrons is investigated and shown to result in a surprising shortening of the longer bonds. The second derivatives of the energy are evaluated and have enabled, for the first time, all the normal modes of the molecule to be found. We find these to be in fair agreement with the available experimental results.
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| 7. |
- Jones, R, et al.
(author)
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Identification of the dominant nitrogen defect in silicon
- 1994
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 72:12, s. 1882-1885
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Journal article (peer-reviewed)abstract
- The structure of the dominant N pair defect in Si is determined from channeling, infrared local vibrational mode spectroscopy, and ab initio local density functional theory. Channeling experiments show that the N atoms are displaced by 1.1±0.1 Å from lattice sites along 〈100〉. Annealing experiments reveal that this N site is associated with two N-related local vibrational modes originating from the N pair. The ab initio calculations demonstrate that the pair consists of two neighboring 〈100〉 oriented N-Si split interstitials, arranged in an antiparallel configuration, and with four N-Si bonds forming a square lying on {011}.
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| 8. |
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| 9. |
- Nielsen, B. Bech, et al.
(author)
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Observation and theory of the H2* defect in silicon
- 1994
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In: Proceedings of the 17th International Conference on Defects in Semiconductors. - : Trans Tech Publications Inc.. ; , s. 845-852
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Conference paper (peer-reviewed)
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| 10. |
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