| 1. |
- Esmaeili, M, et al.
(författare)
-
EFFECT OF THE EXTRINSIC AND TEMPORAL CARRIERS ON RADIATIVE RECOMBINATION OF III-NITRIDE NANOSTRUCTURES
- 2008
-
Ingår i: IRANIAN JOURNAL OF SCIENCE AND TECHNOLOGY TRANSACTION A-SCIENCE. - 1028-6276. ; 32:A3, s. 207-213
-
Tidskriftsartikel (refereegranskat)abstract
- Due to many important applications, the group III-Nitride semiconductors have recently attracted remarkable attention among semiconductor researchers and engineers. In this paper, we report on the impact of extrinsic and temporal carriers on the screening of polarization internal fields. The optical efficiency of GaN/AlGaN multiple quantum well (MQW) nanostructures were studied by means of photoluminescence (PL) and time-resolved PL measurements. Extrinsic carriers come from Si doping in the barriers, while temporal carriers originate when the samples are excited by laser beam. The emission peaks of MQWs in PL spectra of the undoped and low-doped samples show a shift towards higher energy levels as excitation intensity increases, while the other samples do not exhibit such a phenomenon due to the dominance of the extrinsic carriers. The transient data confirm the results of the PL measurements.
|
|
| 2. |
- Momeni, H. R., et al.
(författare)
-
Apoptosis in cultured spinal cord slices of neonatal mouse
- 2008
-
Ingår i: Iranian Journal of Science and Technology Transaction A: Science. - 1028-6276. ; 32:A2, s. 109-116
-
Tidskriftsartikel (refereegranskat)abstract
- Organotypic spinal cord slices from neonatal mammals could be a powerful model for evaluation of cell survival but also cell death mechanisms. The aim of this study was to establish an in vitro model for investigating cell survival and mechanism involved in cell death in neonatal spinal cord slices. The spinal cord was sliced and incubated into culture medium. The MTT assay was carried out to assess the viability of the slices and fluorescent staining was used to study morphological features of apoptosis, where as nucleosomal DNA fragmentation was detected using agarose gel electrophoresis. The results of the present study demonstrated that the slices could be maintained in culture up to 14 days. Both neurons and glial cells died by apoptosis and application of a general caspase inhibitor neither affected slice survival nor nucleosomal DNA fragmentation after 24 h in culture. In addition, the inhibitor failed to block apoptosis in neurons and glial cells in the cultured slices. Our results suggest that in the cultured slices, apoptosis is the main reason for neuron and glial cell death, which occurs by a caspase-independent mechanism.
|
|
