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- Andersson, C B M, et al.
(författare)
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Bulk and surface electronic structure of InAs(110)
- 1998
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 398:3, s. 395-
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Tidskriftsartikel (refereegranskat)abstract
- The InAs(110) cleavage surface has been investigated by angle-resolved photoelectron spectroscopy. A separation between the In 4d(5/2) bulk component and the valence band maximum of 16.8 eV is found to be consistent with normal emission spectra. Experimental energy band dispersions, E-i(k), for the four bulk valence bands are established along the Sigma-line of the bulk Brillouin zone. A bulk band structure calculation utilizing the augmented plane-wave method is made. The experimental and calculated E-i(k) dispersions are found to be in good agreement with each other. E-i(k(parallel to)) dispersions for two surface-related structures are established along the lines <(Gamma)over bar>-(M) over bar and (Y) over bar-(M) over bar of the surface Brillouin zone. (C) 1998 Elsevier Science B.V.
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| 3. |
- Anell, Anders, et al.
(författare)
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Läkemedelskostnaderna
- 1999
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Ingår i: Svensk farmaci under 1900-talet Bd 3 Ekonomi, dokumentation, tillsyn.
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Bokkapitel (populärvet., debatt m.m.)
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| 4. |
- Austrell, Per Erik, et al.
(författare)
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Survey of Design Methods and Material Characteristics in Rubber Engineering
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The unique properties of elastomeric materials are taken advantage of in many engineering applications. Elastomeric units are used as couplings or mountings between stiff structures. Examples of these are shock absorbers, vibration insulators, flexible joints, seals and suspensions.The development of computers and of analysis programs in this area has given engineers a new tool for the design of elastomeric components. Computer simulation by finite element analysis has become increasingly important, allowing the mechanical behavior of products with for complex geometries, as well as loading cases of different kinds to be evaluated. Computer simulations enable both static and dynamic aspects to be analyzed. These matters have been recognized by the manufacturers of rubber products and by their customers. The benefits are shorter time for product development and also quality improvements.However, the possibilities available for finding less complicated technical solutions at lower cost with the use of elastomers, has not been fully utilized. Rubber components could be employed more frequently in design if engineers were more familiar with materials of this sort.Part of the problem lies in education and in the dissemination of information. Engineers working in the design area tend to not be very familiar with elastomeric materials and their properties. The offerings of courses on the mechanics of polymers at schools and universities are very limited. Skillful engineers in this field have usually acquired their knowledge through many years of experience and not formal education.Moreover, the complicated nature of the material behavior involved makes it difficult to devise general design rules and design tools. Only recently have computers and analysis programs become powerful enough for the analysis of nonlinear elastic problems involving large strains.It is essential, if one is to become competitive in high-tech applications, to possess a thorough knowledge of computer methods, material models and test methods available.There has likewise been a lack of relevant data for the computer analysis of elastomeric materials. The design tools employed rely on the material models available and on the test data required for the calibration of these models. In many cases, the only information available for analysis is a value for the hardness of the rubber in question. The wide variety of rubber compounds is also a problem. The characterization of different materials is costly and time-consuming. There is thus a need for simple and reliable methods to characterize the different vulcanizates.
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| 5. |
- Bergsten, Peter, et al.
(författare)
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Appearance of glucose-induced insulin release in fetal rat β-cells
- 1998
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Ingår i: Journal of Endocrinology. - : Society for Endocrinology. - 0022-0795 .- 1479-6805. ; 158:1, s. 115-120
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Tidskriftsartikel (refereegranskat)abstract
- Fetal rat pancreatic cells were isolated from pancreatic primordia on days 12-14 of pregnancy and cultured for 48 h in the presence of 5 mmol/l glucose. Insulin accumulation in the medium over the next 24 h was measured. Cultured cells from day 12 fetuses secreted about 1 fmol insulin per pancreas in response to 5 or 15 mmol/l glucose irrespective of whether 1 mmol/l tolbutamide, 400 mumol/l diazoxide, 5 mmol/l theophylline or 10 mmol/l mannoheptulose was present. In contrast, insulin released from day 13 cultured cells increased significantly from 3.0 +/- 0.6 to 6.2 +/- 2.2 fmol per pancreas, when the glucose concentration was raised. Tolbutamide increased, diazoxide and mannoheptulose decreased and theophylline had no effect on insulin release. Even more pronounced effects were found on insulin release from day 14 cultured cells, in which theophylline also increased the release. In addition, insulin release from cells from pregnancy day 14 was 75 +/- 16 amol/min per pancreas when the cells were perifused for 15-20 min in the presence of 5 mmol/l glucose within 3 h of isolation. Increasing the glucose concentration to 15 mmol/l or adding tolbutamide increased, whereas diazoxide decreased, insulin release in the freshly isolated cells. The insulin content of rat pancreata from pregnancy day 13 was 0.06 +/- 0.01 pmol per pancreas and increased approximately 10-fold every second day up to 6.7 +/- 0.9 pmol on day 17 of pregnancy. Between day 17 and 19 the pancreatic insulin content increased about fivefold to 39 +/- 2 pmol. The present data suggest that critical components of the insulin-secretory machinery, including ATP-regulated K+ channels, glucokinase and adenylate cyclase activities, are present in the developing beta-cell earlier than hitherto thought.
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