Comparison of the Thermal Degradation of Heavily Nb-Doped and Normal PZT Thin Films.

The degradation of niobium-doped lead zirconate titanate (PZT) and two types of PZT thin films were investigated. Undoped PZT, two-step PZT, and heavily Nb-doped PZT (PNZT) around the morphotropic phase boundary were in situ deposited under optimum condition by RF-magnetron sputtering. All 2- [Formula: see text]-thick films had dense perovskite columnar grain structure and self-polarized (100) dominant orientation. PZT thin films were deposited on Pt/TiOx bottom electrode on Si wafer, and PNZT thin film was on Ir/TiW electrode with the help of orientation control. Sputtered PZT films formed on microelectromechanical system (MEMS) gyroscope and the degradation rates were compared at different temperatures. PNZT showed the best resistance to the thermal degradation, followed by two-step PZT. To clarify the effect of oxygen vacancies on the degradation of the film at high temperature, photoluminescence measurement was conducted, which confirmed that oxygen vacancy rate was the lowest in heavy PNZT. Nb-doping PZT thin films suppressed the oxygen deficit and made high imprint with self-polarization. This defect distribution and high internal field allowed PNZT thin film to make the piezoelectric sensors more stable and reliable at high temperature, such as reflow process of MEMS packaging.

Prevalent genotypes of methylenetetrahydrofolate reductase (MTHFR C677T and A1298C) in spontaneously aborted embryos.

OBJECTIVE: To assess prevalent 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphisms in spontaneously aborted embryos. DESIGN: A retrospectively analyzed, prospectively obtained database. SETTING: Bundang CHA General Hospital and Kangnam CHA Hospital. PATIENT(S): Ninety-four spontaneously aborted embryos at <20 weeks of gestational age. INTERVENTION(S): None. MAIN OUTCOME MEASURE: Genotype frequency of MTHFR C677T and A1298C polymorphisms in spontaneously aborted embryos. RESULT(S): The aborted embryos exhibited both a significantly high frequency of the MTHFR 677CC genotype and a low frequency of the MTHFR 677CT genotype, compared to both the child and the adult control groups, respectively, whereas no significant change in the fetal MTHFR A1298C genotype frequency was observed. The combinative genotype of MTHFR 677CC/1298AC from the abortus had a high prevalence compared to the child controls. Further, the chromosomal integrity of the abortus did not affect the frequency of the MTHFR 677CC and 1298AC genotypes. CONCLUSION: Spontaneously aborted embryos have a unique distribution of MTHFR C677T and A1289C polymorphisms, regardless of their chromosomal integrity.