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| 2. |
- Bergstrom, H, et al.
(författare)
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Investigations of radiative lifetimes in the 3p 5p configuration of neutral silicon
- 1989
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Ingår i: Zeitschrift für Physik D Atoms, Molecules and Clusters. - 0178-7683. ; 13:1, s. 29-31
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Tidskriftsartikel (refereegranskat)abstract
- Lifetimes for the3S1,3P0, 1, 2 and3D1, 2, 3 states in the 3s23p5p configuration of silicon have been determined using stepwise dye laser excitation and time resolved detection. A comparison is made with theoretical values, calculated using multi-configuration Hartree-Fock wavefunctions. Laser-evaporation was used to produce free silicon atoms by focusing a Nd: YAG laser on a rotating silicon target.
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| 3. |
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| 4. |
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| 5. |
- Gerdin, Bengt, 1947-, et al.
(författare)
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Permeability-increasing ability of PAF-acether in rat skin.
- 1985
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Ingår i: Inflammation. - 0360-3997 .- 1573-2576. ; 9:1, s. 107-12
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Tidskriftsartikel (refereegranskat)abstract
- Platelet-activating factor (PAF-acether), a phospholipid compound with effects on several cells, e.g., platelets and polymorphonuclear leukocytes (PMNs), was examined for its effect on microvascular permeability in rat skin. It was found to increase microvascular permeability, measured as exudation of [125I]human serum albumin, in amounts exceeding 1 pmol, and was more than 1000 times as potent as histamine. The effect was independent of cell infiltration, as no accumulation of PMNs, measured as the amount of myeloperoxidase in the skin, occurred and as the response was unaltered in animals rendered neutropenic due to treatment with an antiserum against PMNs.
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| 6. |
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| 7. |
- Grafström, Peter, et al.
(författare)
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Hyperfine structure and isotope shift of highly excited barium-I states
- 1982
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Ingår i: Zeitschrift für Physik A Hadrons and Nuclei. - 0939-7922. ; 306:4, s. 281-284
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution laser-spectroscopy measurements of hyperfine structure and isotope shifts were performed for the 6snd 1 D 2 sequence of Ba-I in the regionn=12–24. Stepwise laser excitations of a collimated atomic beam were used. A strong influence on the hyperfine structure is observed at the perturbation atn=14, caused by interaction with the 5d7d configuration. Whereas the isotope shift for the even isotopes stays essentially constant with increasingn, the odd isotopes exhibit a strong change, indicating hyperfine-induced shifts. Interesting discussions with Prof. E. Matthias in the final stage of this work are gratefully acknowledged. This work was supported by the Swedish Natural Science Research Council.
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| 8. |
- Grundevik, P, et al.
(författare)
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Hyperfine structure in the 6p5d configuration and isotope shifts in transitions between the 6s5d and the 6p5d configurations in Ba I
- 1982
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Ingår i: Zeitschrift für Physik A Hadrons and Nuclei. - 0939-7922. ; 306:3, s. 195-209
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution laser fluorescence spectroscopy, using a single-mode dye laser acting on a collimated atomic beam, has been performed to determine the hyperfine-structure (hfs) constants in six states of the 6p 5d configuration of135Ba and137Ba. Isotope shifts (IS) for eleven transitions between the 6s 5d and the 6p 5d configurations have also been measured. From an analysis of the energy levels, intermediate angular wavefunctions have been deduced. The wavefunctions are used to evaluate experimental hyperfine parameters from the experimental hfs constants. The parameters are, for the magnetic-dipole interaction compared with theoretical values, and for the electricquadrupole interaction used to estimate the nuclear quadrupole moments for the odd isotopes.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Jonsson, G, et al.
(författare)
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Hyperfine structure and radiative lifetimes in the 3s2n p2P3/2 sequence of Al-27 using time resolved laser spectroscopy
- 1984
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Ingår i: Zeitschrift für Physik A Hadrons and Nuclei. - 0939-7922. ; 316:3, s. 259-263
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Tidskriftsartikel (refereegranskat)abstract
- Using time-resolved laser spectroscopy we have determined the hyperfine structure in the 3s2n p2P3/2 sequence of27Al (I=5/2). The magnetic-dipole interaction constants were found to scale withn*-2.85 (n* is the effective principal quantum number) in the investigated regionn=6–12. Significant quadrupole interaction constants were obtained forn=6–9. The measured radiative lifetimes forn=6–12 scale withn*2.
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| 13. |
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| 14. |
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| 15. |
- Karlsson, Lars G., et al.
(författare)
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Experimental study of a percussive process for rock fragmentation
- 1989
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Ingår i: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts. - 0148-9062 .- 1879-2073. ; 26:1, s. 45-50
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of a percussive process for fragmentation of rock and similar materials has been studied experimentally. The percussive system comprised a cylindrical hammer and a cylindrical bit with the same characteristic impedance. The bit was terminated with a wedge. In front of the wedge there was a heavy block of concrete. The length of the bit and the initial gap between bit and concrete were varied systematically. The force versus penetration relationship and the work of fragmentation were determined in each test using a new technique based on measurement of strains at two cross-sections of the bit. Each test was simulated individually using a previously developed one-dimensional model. The results of simulations and experimental tests were found to agree well.
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| 16. |
- Lundberg, Bengt, et al.
(författare)
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Influence of geometrical design on the efficiency of a simple down-the-hole percussive drill
- 1986
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Ingår i: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts. - : Elsevier BV. - 0148-9062 .- 1879-2073. ; 23:3, s. 281-287
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Tidskriftsartikel (refereegranskat)abstract
- In the present investigation, the simulation program DTH-SIM is used to determine the efficiency of a simple down-the-hole percussive drill, which has the main features of a practical design. The efficiency is obtained as a function of the same dimensionless parameters as in a preceding study of two additional parameters which represent the characteristic impedance and the length of the head of the bit. Several results obtained here for non-uniform bits differ considerably from those established previously for uniform bits
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| 17. |
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| 18. |
- Lundberg, Peter, et al.
(författare)
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Phosphorus-31 and Nitrogen- 14 NMR Studies of the Uptake of Phosphorus and Nitrogen Compounds in the Marine Macroalgae Ulva lactuca
- 1989
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 89:4, s. 1380-1387
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Tidskriftsartikel (refereegranskat)abstract
- Cytoplasmic phosphomonoesters and inorganic phosphate, as well as vacuolar inorganic phosphate and polyphosphates, gave rise to the major peaks in (31)P nuclear magnetic resonance (NMR) spectra of the marine macroalgae Enteromorpha sp., Ceramium sp., and Ulva lactuca which were collected from the sea. In contrast, NMR-visible polyphosphates were lacking in Pylaiella sp. and intracellular vacuolar phosphate seemed to act as the main phosphorus store in this organism. In laboratory experiments, polyphosphates decreased in growing U. lactuca which was cultivated in continuous light under phosphate-deficient conditions. In contrast, the same organism cultivated in seawater with added phosphate and ammonium, accumulated phosphate mainly in the form of polyphosphates. When nitrate was provided as the only nitrogen source, accumulation of polyphosphates in the algae decreased with increasing external nitrate concentration. From the chemical shift of the cytoplasmic Pi peak, the cytoplasmic pH of superfused preparations of Ulva was estimated at 7.2. The vacuolar pH, determined from the chemical shifts of the vacuolar Pi and the terminal polyphosphate peaks, was between 5.5 and 6.0. The intracellular nitrate and ammonium levels in U. lactuca were determined by (14)N NMR. Both nitrogen sources were taken up and stored intracellularly; however, the uptake of ammonium was much faster than that of nitrate.
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| 19. |
- Schoenberg, M H, et al.
(författare)
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Hemorrhagic shock in the dog. II. Studies on central hemodynamics and regional blood flow.
- 1985
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Ingår i: Research in experimental medicine. - 0300-9130 .- 1433-8580. ; 185:6, s. 469-82
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen consumption, hemodynamics, and regional blood flow (with the radioactive microspheres technique) were determined in 12 anesthetized dogs subjected to hemorrhagic shock. The animals were kept in hypotension at 40 mmHg, until 15% of the maximum shed blood had been infused to keep arterial pressure stable, whereafter all the shed blood was retransfused. Cardiac output (CO) decreased to 33% and 25% of preshock values in survivors (S) and nonsurvivors (NS), respectively, and after retransfusion it was significantly higher in S. After retransfusion, NS showed a higher arterial pCO2 than S adding a respiratory component to the metabolic acidosis that occurred during and after hemorrhage. Blood flow to the brain was not impeded during shock, but as CO decreased the fraction delivered to the brain was increased 2.6-3.3-fold. Myocardial blood flow decreased to about 28% of preshock values immediately after hemorrhage, and increased to about 54% at the end of hemorrhage. After retransfusion S had a higher myocardial flow than NS. The flow to the gut paralleled the decrease in CO during hemorrhage and immediately after retransfusion NS exhibited an overperfusion in ileum and colon compared to the preshock values. Kidney blood flow fell progressively during the course of hypotension, similarly in S and NS. After retransfusion it was normalized in S but not in NS. The preshock flow to pancreas was significantly higher in S than in NS, but during and after shock the blood flow did not differ between S and NS.
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| 20. |
- Weich, Rainer G., et al.
(författare)
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Phosphorus-31 NMR studies of cell wall-associated calcium-phosphates in Ulva lactuca
- 1989
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 90:1, s. 230-236
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Tidskriftsartikel (refereegranskat)abstract
- Phosphate concentrations in the range 0.1 to 2.0 millimolar induced the formation of extracellular amorphous calcium-phosphates in the cell wall of the marine macro algae Ulva lactuca when they were cultivated in light in seawater at 20°C. A broad resonance representing these compounds as well as resonances for extracellular orthophosphate and polyphosphates could be followed by 31P-nuclear magnetic resonance spectroscopy. The presence of the calcium-phosphate made the cells brittle and it inhibited the growth of the macro algae and caused mortality within 1 week. The formation of the calcium-phosphates was influenced by the external phosphate concentration, the extracellular pH and the nature and concentration of the external nitrogen source. Furthermore, no formation of these compounds was observed when Ulva lactuca was cultivated in the dark, at low temperatures (5°C) or in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. The complex could be removed through washes with ethylenediaminetetraacetate; this treatment did not alter the intracellular pH or the orthophosphate and polyphosphate pools and it restored growth.
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