| 1. |
|
|
| 2. |
- Buyanova, Irina, 1960-, et al.
(författare)
-
Electronic structure of the 0.88-eV luminescence center in electron-irradiated gallium nitride
- 1999
-
Ingår i: Physical review. B, Condensed matter and materials physics. ; 60:3, s. 1746-1751
-
Tidskriftsartikel (refereegranskat)abstract
- Photoluminescence (PL) spectroscopy is employed to determine the nature of a near-infrared PL emission with a no-phonon line at ∼0.88 eV, commonly present in electron-irradiated GaN. This PL emission is suggested to originate from an internal transition between a moderately shallow excited state (with an ionization energy ∼21 meV) and the deep ground state (with an ionization energy ∼900 meV) of a deep defect. The existence of a higher-lying second excited state related to the 0.88-eV PL center is also shown from temperature-dependent studies. A different electronic character of the wave functions related to the first and second excited states has been revealed by PL polarization measurements. Since the PL emission has been observed with comparable intensity in all electron-irradiated GaN samples independent of doping on the starting material, it is proposed that either native defects, or common residual contaminants or their complexes are involved. The substitutional ON donor (or related complex) is considered as the most probable candidate, based on the observed striking similarity in the local vibrational properties between the 0.88-eV PL centers and the substitutional OP donor in GaP.
|
|
| 3. |
- Edwards, A V, et al.
(författare)
-
Nitric oxide and release of the peptide VIP from parasympathetic terminals in the submandibular gland of the anaesthetized cat.
- 1996
-
Ingår i: Experimental physiology. - 0958-0670. ; 81:3, s. 349-59
-
Tidskriftsartikel (refereegranskat)abstract
- The role of nitric oxide (NO) in mediating various submandibular responses to stimulation of the parasympathetic innervation has been investigated in anaesthetized cats, in which N omega-nitro-L-arginine methyl ester (L-NAME; 30 mg kg-1 I.A.) was used to block the synthesis of NO. L-NAME significantly reduced the vasodilator response and the flow of saliva, together with the output of salivary protein that occurred during stimulation of the chorda lingual nerve (20 Hz for 1 s at 10 s intervals), without significantly reducing the output of vasoactive intestinal peptide (VIP) from the gland. The results show that NO is implicated not only in the release of VIP, as established previously, but also in mediating its actions following release in the submandibular gland of the cat.
|
|
| 4. |
|
|
| 5. |
- Kipling, D, et al.
(författare)
-
Telomere-dependent senescence
- 1999
-
Ingår i: NATURE BIOTECHNOLOGY. - : NATURE AMERICA INC. ; 17:4
-
Annan publikation (övrigt vetenskapligt/konstnärligt)
|
|
| 6. |
- López-Puertas, M., et al.
(författare)
-
Non-local thermodynamic equilibrium limb radiances for the mipas instrument on Envisat-1
- 1998
-
Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - 0022-4073 .- 1879-1352. ; 59:3-5, s. 377-403
-
Tidskriftsartikel (refereegranskat)abstract
- An evaluation of the effects that the assumption of local thermodynamic equilibrium (LTE) has on the retrieval of pressure, temperature and the five primary target gases (O3, H2O, CH4, N2O, and HNO3) from spectra to be taken by Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on the Envisat-1 platform has been conducted. For doing so, non-LTE and LTE limb radiances in the spectral range of 680–2275 cm−1 (4.15–14.6 μm) with a resolution of 0.05 cm−1 at tangent heights from 10 to 70 km have been computed. These calculations included the most updated non-LTE populations of a large number of vibrational levels of the CO2, O3, H2O, CH4, N2O and HNO3 molecules which cause the most prominent atmospheric infrared emissions. A discussion of the most important non-LTE effects on the limb radiances as well as on the retrievals of pressure-temperature and volume mixing ratios of O3, H2O, CH4, N2O, and HNO3 is presented, together with the most important non-LTE issues that could be studied with the future coming of MIPAS data.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Tobin, Gunnar, 1954, et al.
(författare)
-
Nitric oxide in the control of submandibular gland function in the anaesthetized ferret.
- 1997
-
Ingår i: Experimental physiology. - 0958-0670. ; 82:5, s. 825-36
-
Tidskriftsartikel (refereegranskat)abstract
- Stimulation of parasympathetic innervation of the submandibular gland (2 or 20 Hz continuously or 20 Hz for 1 s at 10 s intervals), in the ferret, produced secretion of fluid and protein and a fall in vascular resistance. The responses following the administration of N omega-nitro-L-arginine methyl ester (L-NAME; 2 mmol kg-1 i.a.) to block the synthesis of nitric oxide (NO) were reduced, and the persisting responses were abolished (at 2 Hz continuously and 20 Hz intermittently) or further reduced (at 20 Hz continuously) by the additional administration of atropine. The output of vasoactive intestinal peptide (VIP) from the gland was not affected. Neither the secretory nor the vascular response to intra-arterial infusions of acetylcholine (1.25 nmol kg-1) was affected by L-NAME, whereas the vascular responses to both VIP (10 pmol kg-1) and pituitary adenylate cyclase-activating peptide (1-38) (PACAP) (0.5 pmol kg-1) were reduced thereby. Neither peptide evoked a fluid secretion per se. However, when infused during parasympathetic stimulation of saliva secretion, VIP increased both flow rate and the output of protein. These effects of VIP were abolished by L-NAME. The experiments were performed in the presence of sodium nitroprusside at doses (4-8 nmol min-1 kg-1 i.v.) aimed to counterbalance the systemic effects of L-NAME. The results show that, in the ferret, parasympathetic nerve activity increases submandibular blood flow, and elicits the flow of saliva and output of protein by mechanisms that involve in situ generation of NO, upon which the effects of VIP and PACAP but not acetylcholine are largely dependent.
|
|
