| 11. |
|
|
| 12. |
|
|
| 13. |
- Johansson, B, et al.
(författare)
-
Responses of smooth muscle to quick load change studied at high time resolution
- 1978
-
Ingår i: Blood Vessels. - 0303-6847. ; 15:1-3, s. 65-82
-
Tidskriftsartikel (refereegranskat)abstract
- Quick-release and quick-stretch experiments have been performed on preparations of smooth muscle from rat portal vein and rabbit urinary bladder. The low equivalent mass of the isotonic lever (8 mg) implied that inertial oscillations were limited to the first 5-10 msec after the load step. The high time resolution achieved in this way enabled us to separate three components in the length response to a step change in force: (1) an immediate passive elastic recoil, (2) an isotonic velocity transient lasting 50-75 msec and (3) shortening of the contractile element after its full adjustment to the new load. The maximal series elastic recoil was about 10% of the total muscle length in portal vein but only some 3% in urinary bladder. Stiffness of series elasticity increased in proportion to force and was about 3 times higher in bladder than in portal vein at any force level. Force-velocity relations for loads less than Po could be fitted to Hill's equation; Vmax in 4 AC-stimulated portal veins was 0.53 +/- 0.03 muscle lengths/sec and in 8 K+-activated bladder preparations 0.18 +/- 0.01 muscle lengths/sec. Application of loads greater than Po produced rates of lengthening greater than expected from an extrapolation of Hill's hyperbola. The nature of the transient component is discussed in the light of recent studies of force and velocity transients in skeletal muscle.
|
|
| 14. |
- Johansson, L. B. A., et al.
(författare)
-
Micelle studies by high-sensitivity linear dichroism. Benzene solubilization in rod-shaped micelles of cetyltrimethylammoniumbromide in water
- 1976
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 39:1, s. 128-133
-
Tidskriftsartikel (refereegranskat)abstract
- A high-sensitivity linear dichroism (LD) technique has been employed in studying the indirect orientation of benzene by solubilization in rod-shaped micelles in a system of cetyltrimethylammoniumbromide (CTAB): water, oriented by flow in a couvette device. The dependence of the LD signal due to the π-π* transitions in the benzene plane on the temperature, on the shear gradient and on the benzene concentration, has been investigated. The net positive LD, observed from the benzene chromophore, derives from benzene orientation at the surface of the rod-shaped micelles. The orientation of the micelle rods is very high and the system is suggested for use as a standard matrix for studying solubilized molecules in polarized spectroscopy.
|
|
| 15. |
|
|
| 16. |
|
|
| 17. |
|
|
| 18. |
- Nelander, B., et al.
(författare)
-
Optically active low-temperature inversion stabilised 1,2-dithiane by photolysis with circularly polarised light
- 1974
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 28:3, s. 384-386
-
Tidskriftsartikel (refereegranskat)abstract
- Optically active 1,2-dithiane has been produced in a hydrocarbon g ass at 77 K by photolysis with circularly polarised light. Its CD spectrum (above 270 nm) consists of a single symmetric component coinciding with the position of the low energy absorption band. The possibility of using the method to study any per se chiral but at room temperature statistically optically inactive molecule is stressed. A relation yielding Δϵ is presented.
|
|
| 19. |
|
|
| 20. |
- Nordén, Bengt, 1945, et al.
(författare)
-
The magnetic circular dichroism of five-membered ring heterocycles
- 1978
-
Ingår i: Chemical Physics. - : Elsevier BV. - 0301-0104. ; 33:3, s. 355-366
-
Tidskriftsartikel (refereegranskat)abstract
- The MCD spectra of pyrrole, furan, thiophene, selenophene and teburophene and some of their derivatives are reported and the corresponding energies, oscillator strengths, transition moment directions, and MCD terms are calculated from semi-empirical quantum mechanical calculations hi the π-electron approximation. The MCD spectrum of thiophene is only slightly perturbed by substituents, and this is also expected to be true of the quite similar MCD spectra of selenophene and tellurophene. These molecules can then be classified as “hard” chromophores. On the other hand, pyrrole and furan have different and much weaker MCD spectra which change shape considerably when substituents are introduced. The implications of these observations are further discussed.
|
|
