Structural Phase Transition and a Mutation of Electron Mobility in Zn_xCd_(1-x)O Alloys

We investigate the electronic structures and phase stability of ZnO, CdO and the related alloys in rocksalt（B1）and wurzite（B4） crystal, using the first-principle density functional theory within the hybrid functional approximation. By varying the concentration of Zn components from 0% to 100%, we find that the Zn_xCd（1-x）O alloy undergoes a phase transition from octahedron to tetrahedron at x = 0.32, in agreement with the recent experimental findings. The phase transition leads to a mutation of the electron mobility originated from the changes of the effective mass. Our results qualify Zn O/Cd O alloy as an attractive candidate for photo-electrochemical and solar cell power applications.

A sensitive method to detect the hepatitis B virus mutations by using solid phase PCR on oligonucleotide array

A sensitive method based on solid phase PCR on oligonucleotide array was established to detect two point mutations 1896G-A and 1901G-A in hepatitis B virus (HBV) DNA, in which 6 probes including these two point mutations were immobilized on modified glass slides through 5' terminal linker, while the 3' terminal was made to be free. The mutated loci were designed to locate on the last nucleotides of 3' terminal respectively, and the positive control probes lacked the last nucleotide of 3' terminal in comparison with the probes used for detection. Probes fixed on oligonucleotide array were also the solid phase amplification primers. One pair of liquid primers was used to amplify the short template product from whole HBV DNA. Using target DNA as template, the solid primers were extended under the action of Taq DNA polymerase and incorporated with Cy-3dCTP as marker. During the thermal cycling reaction, probes served as solid phase amplification primers and amplification products bound to the oligonucleotide array, which could be visualized by incorporation with fluorescent dyes. After amplification, the oligonucleotide array was washed, performed with laser scanning, and then used for quantitative analysis to obtain the information for mutations. The hybridization results were compared with DNA sequencing. It was demonstrated that in case of sample A, the ratios of fluorescence intensities in wide type and in the mutated types of 1896G-A and 1901G-A mutations in HBV were 3.81:1 and 1:3.79 respectively, while, in case of sample B, those were 1:2.89 and 1:3.03 respectively, indicating the presence of point mutations in these two loci. These results correlated to those obtained from DNA sequencing analysis in which the fluorescence intensity ratios in wide type and in the mutated types of 1996G-A and 1901D-A mutations in HBV were 1.26:1 and 1.67:1 respectively. From the above observations, it is evident that the method using solid phase PCR based on oligonucleotide array appears to be a sensitive and promising way to detect mutations with low-density.