Temperature-dependent photoluminescence of a wurtzite GaN epilayer was measured in the range of 4 to 300 K. At low temperature, the neutral-donor bound exciton emission dominates the spectra, while with increasing temperature, free exciton emissions grow rapidly and finally become the dominant lines. The contribution of the exciton-phonon interaction to the exciton linewidth was studied. Beside the exciton emissions, LO-phonon-assisted photoluminescence associated with both the bound exciton and the free exciton was observed. The temperature dependence of LO-phonon-assisted emissions can be well explained by the phonon-assisted free exciton emission theory established for II-VI compound semiconductors by Permogorov. In particular, the study of the 2LO phonon replica can provide information on the temperature dependence of the concentration and recombination lifetime of free excitons in GaN.

The vp28 gene encoding an envelope protein (28 kDa) of white spot syndrome virus (WSSV) was amplified from WSSV-infected tiger shrimp that originated from Malaysia. Recombinant VP28 protein (r-28) was expressed in Escherichia coli and used as an antigen for preparation of monoclonal antibodies (MAbs). Three murine MAbs (6F6, 6H4 and 9C10) that were screened by r-28 antigen-based enzyme-linked immunosorbent assay (ELISA) were also able to recognize viral VP28 protein as well as r-28 on Western blot. Three non-overlapping epitopes of VP28 protein were determined using the MAbs in competitive ELISA; thus, an antigen-capture ELISA (Ac-ELISA) was developed by virtue of these MAbs. Ac-ELISA can differentiate WSSV-infected shrimp from uninfected shrimp and was further confirmed by a polymerase chain reaction (PCR) and Western blot. Approximately 400 pg of purified WSSV sample and 20 pg of r-28 could be detected by Ac-ELISA, which is comparable in sensitivity to PCR assay but more sensitive than Western blot in the detection of purified virus. Hemolymph and tissue homogenate samples collected from a shrimp farm in Malaysia during December 2000 and July 2001 were also detected by Ac-ELISA and PCR with corroborating results.

The MCPB system is not associated with a lower incidence of AKI in Asian patients undergoing CABG. Risk factors for AKI differed between patients using the MCPB and CCPB systems.

Inductively coupled plasma (ICP) etching of GaN is investigated using BCl 3 /Cl 2 chemistry. The maximum etch rate is observed when the percentage of Cl 2 in the BCl 3 /Cl 2 gas mixture is about 80-100%. From photoluminescence (PL) study of the etched GaN samples, we found that the ICP etching creates non-radiative surface recombination states and it has been observed that the creation of surface states is a minimum when the Cl 2 in the BCl 3 /Cl 2 mixture is about 90-100%. The atomic force microscope (AFM) study shows that the etching does not make the surface rough and the root mean square (rms) roughness of the etched surface is about 3-5 nm.

Optical absorption and photoluminescence (PL) measurements have been made on the quantum dots (QDs) of CdS grown in a borosilicate glass matrix using a two-step annealing technique. The absorption measurements, made in the energy range of 1.3-3.2 eV, indicate the presence of nonradiative trap centers located in the forbidden gap at an energy level near 1.5 eV. The origin of these traps is attributed to the impurities present in the glass matrix. The PL measurements have been made at an excitation energy of 2.75 eV and it is concluded that the origin of PL is not due to either direct recombination of electrons and holes or deep traps, but that it is the shallow traps which are responsible for the observed PL. The shallow traps are attributed to sulfur vacancies formed at the glass-QD interface. The reason for the observed decrease in PL peak intensity with the increase of annealing time is due to the decrease of surface to volume ratio for QDs of higher size.