| 1. |
- Paul, Jan, et al.
(författare)
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The vibrational bands of carbon monoxide bound to hemes or metal surfaces
- 1985
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Ingår i: Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology. - : Elsevier BV. - 0167-4838 .- 1879-2588. ; 832:3, s. 257-264
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Tidskriftsartikel (refereegranskat)abstract
- Infrared spectra of imidazole carbonyl complexes of 2,4-substituted hemes are presented. An increased CO stretch frequency is accompanied by a lowered FeC vibrational energy. Hartree-Fock-Slater electron structure calculations discern π and σ contributions to the observed shifts of vibrational energies. We conclude that an enhanced electron availability manifests itself as (i) a lowered ferric/ferrous reduction potential, (ii) increased filling of the 2π orbital of liganded CO which in turn reduces νCO and increases νFec, and (iii) increased basicity of the liganded CO. Analogies between CO liganded to heme and CO adsorbed onto metal surfaces are discussed.
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| 2. |
- Petfordlong, Amanda K., et al.
(författare)
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On the growth of small crystals of Cd, Zn, Pt and Rh during electron microscope observations
- 1987
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 80:2, s. 218-224
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Tidskriftsartikel (refereegranskat)abstract
- The growth of small supported metal crystals under the influence of an electron beam has been studied in real-time using a 400 keV ultra-high-resolution electron microscope. Samples of Pt, Rh, Cd and Zn supported on amorphous C or Si films were prepared ex situ and crystal growth in situ was recorded directly using a TV imaging/video system attached to the microscope. The different types of observed crystal growth are reported: the fcc metals (Pt and Rh) grow by coalescence, or by the addition of atoms along the particle surface followed by structural rearrangements which result in approximately spherical particles. The hcp metals (Cd and Zn) grow in the form of long rafts along the surface of the substrate film.
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| 3. |
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| 4. |
- Smith, Henrik G., et al.
(författare)
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Feeding freqency and parental division of Labour in the double-brooded great tit Parus major
- 1988
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Ingår i: Behavioral Ecology and Sociobiology. - 1432-0762. ; 22, s. 447-453
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Tidskriftsartikel (refereegranskat)abstract
- We studied the relative contribution of each sex and total effort expended in feeding nestlings in the great tit Parus major in relation to artificially altered brood size. A recent model suggests that feeding frequency should reflect the optimal trade-off between parental and fledgling survival, the former being negatively, the latter positively, influenced by high feeding frequencies. In both sexes weight loss was linearly related to feeding frequency. Since fledgling survival increases with nestling weight, the conditions of this model are fulfilled. However, in contrast to the predictions of the model, the total feeding frequency for both sexes combined did not differ between control and enlarged broods, but was lower for reduced ones. This outcome was not the result of a physiologically related inability of the parents to increase their delivery rate. Instead, we suggest that parents with enlarged broods could not find sufficient amounts of prey large enough to be economically worth transporting to the nest. Differences in brood-provisioning rates between the sexes may arise because costs and benefits of feeding nestlings may differ. Females lost more weight than males during the nesting period, but maintained a relatively higher weight during the incubation period. The relationship between weight loss and feeding frequency was similar for both sexes. Male and female brood-feeding frequency was related to brood size in a similar way. This is discussed in light of the great tit's mating system and the fact that the great tit is facultatively double-brooded.
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| 5. |
- Smith, S M, et al.
(författare)
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Role of neutrophils in hemorrhagic shock-induced gastric mucosal injury in the rat
- 1987
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Ingår i: Gastroenterology. - 0016-5085 .- 1528-0012. ; 93:3, s. 466-471
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Tidskriftsartikel (refereegranskat)abstract
- Gastric mucosal clearance of 51Cr-labeled red blood cells (51Cr-RBC) was measured in rats during a 30-min control period, a 30-min ischemic period (hemorrhage to 27 mmHg arterial pressure), and a 60-min reperfusion period (reinfusion of shed blood). In untreated (control) rats, a dramatic rise in the leakage of 51Cr-labeled red blood cells into the gastric lumen was observed during the reperfusion period. Treatment with neutrophil antiserum attenuated 51Cr-labeled red blood cell flux into the gastric lumen. Using the radioactive microsphere technique, neutrophil-depleted animals were shown to have higher blood flows in the ischemic period than the untreated rats. Bleeding of untreated rats to a mean arterial pressure of 40 mmHg resulted in blood flows that were not different from those in antiserum-treated rats bled to 27 mmHg and leakage of 51Cr-labeled red blood cells similar to that measured in antiserum-treated rats. The results of this study indicate that neutrophils play an important role in hemorrhagic shock-induced gastric bleeding.
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| 6. |
- Wallenberg, LR, et al.
(författare)
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Atomic-resolution study of structural rearrangements in small platinum crystals
- 1986
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Ingår i: Ultramicroscopy. - : Elsevier BV. - 0304-3991. ; 20:1-2, s. 71-75
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Tidskriftsartikel (refereegranskat)abstract
- Structural rearrangements in small Pt crystals, which were initiated by the incident electron beam, have been studied in real time with a 400 kV high-resolution electron microscope equipped with TV image viewing and videorecording facilities. The phenomena of crystal growth, particle coalescence and atomic clouds above particular surfaces were recorded at the atomic level and have been analysed using frame-by-frame playback facilities.
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