No abstract

Dense Cu-doped CaBi4Ti4O15 ferroelectric ceramics have been fabricated by a conventional ceramic technique. After doping by Cu, the ceramics become denser, and their electrical, piezoelectric and pyroelectric properties are improved. At the optimum doping level of 0.5 mol%, the ceramic exhibits a high density (6940 kg m−3), a low dielectric constant (145), a low dielectric loss (0.12%), a high resistivity (2.5 × 1013 Ω cm), a large piezoelectric coefficient (12.4 pC N−1) and a large pyroelectric coefficient (86 µC K−1 m−2). Unlike the piezoelectric properties, the pyroelectric properties, in particular those relating to the pyroelectric detection, of the ceramics are good and comparable to those of the lead-based ferroelectric ceramics. For the ceramic doped with 0.5 mol% Cu, the voltage and detectivity figures of merit for pyroelectric detection have large values of 2.6 × 10−2 m2 C−1 and 2.7 × 10−5 Pa−1/2, respectively, indicating that it is a promising candidate for pyroelectric applications.

To evaluate compatibility of commonly used colorimetric protein assays for 2-DE experiments, we investigated the interfering mechanisms of major 2-DE component(s) in the Lowry-based assay, the Bradford assay and the bicinchoninic acid (BCA) assay. It was found that some 2-DE components did not directly interfere with the assays' color development reaction, but possibly influenced the quantitation results by interacting with proteins. Generally, simultaneous presence of 2-DE components in the samples demonstrated a cooperative rather than additive interference. Interference by reductants in the Lowry-based assay and the BCA assay were too prominent and could not be completely eliminated by either the reported alkylation procedure or the water dilution procedure. The Bradford assay however, presented a more suitable method for quantitating 2-DE samples because it was less interfered by most 2-DE components. Furthermore, despite slightly compromising protein solubility, utilization of reductant free 2-DE sample buffers conferred application of the Lowry-based and BCA assays in the 2-DE experiments.

Tungsten oxide (WO x ) films were fabricated by (i) reactive thermal evaporation (RTE) at room temperature with oxygen ambient pressure P O 2 as a parameter, and (ii) reactive magnetron sputtering (RMS) with substrate temperature T s as a parameter. The film structure revealed by x-ray photoelectron spectroscopy, x-ray diffraction, density measurements, infrared absorption, and atomic force microscopy was correlated with the nanoindentation hardness H. The RTE WO x films deposited at high P O 2 were amorphous and porous, while H depended appreciably on normalized penetration depth h D (indentation depth/film thickness) due to the closing of the pores at the point of indentation. Decrease in P O 2 from 10 to 2 × 10 −3 mtorr led to smaller porosity, weaker h D dependence of H, and higher average H (measured at h D ≈ 0.2 to 0.3, for example). The RMS WO x film deposited at room temperature was amorphous and denser than all RTE films. The rise in substrate temperature T s first densified the film structure (up to 110°C) and then induced crystallization with larger grain size for T s ജ 300°C. Correspondingly, the h D dependence of H became weaker. In particular, H of the RMS sample deposited at 110°C showed a peak at h D slightly above 1 owing to pileup at the contact point of indentation. For higher T s , pileup occurred at shallower h D and the average H (measured at h D ≈ 0.2 to 0.3, for example) rose, accompanied by the increase of grain size.