A First Approach to White Organic Electroluminescence Device from a Single Rod‐Coil Poly[thiophene‐block‐(N‐vinylcarbazole)] Diblock Copolymer

A rod‐coil block copolymer consisting of poly(3‐hexylthiophene) (P3HT) and poly(N‐vinylcarbazole) (PVK) ( P3HT‐ b ‐PVK ) in a single molecular architecture is prepared as the first example for WOLEDs. By obtaining the phase separated domains in thin film of the resulting block copolymer, it is possible to suppress energy transfer from PVK as wide bandgap units to P3HT as low bandgap blocks, yielding dual emissions for white electroluminescence with CIE coordination of (0.34, 0.33).

     

A novel power spectrum calculation method using phase-compensation and weighted averaging for the estimation of ultrasound attenuation

An estimation of ultrasound attenuation in soft tissues is critical in the quantitative ultrasound analysis since it is not only related to the estimations of other ultrasound parameters, such as speed of sound, integrated scatterers, or scatterer size, but also provides pathological information of the scanned tissue. However, estimation performances of ultrasound attenuation are intimately tied to the accurate extraction of spectral information from the backscattered radiofrequency (RF) signals. In this paper, we propose two novel techniques for calculating a block power spectrum from the backscattered ultrasound signals. These are based on the phase-compensation of each RF segment using the normalized cross-correlation to minimize estimation errors due to phase variations, and the weighted averaging technique to maximize the signal-to-noise ratio (SNR). The simulation results with uniform numerical phantoms demonstrate that the proposed method estimates local attenuation coefficients within 1.57% of the actual values while the conventional methods estimate those within 2.96%. The proposed method is especially effective when we deal with the signal reflected from the deeper depth where the SNR level is lower or when the gated window contains a small number of signal samples. Experimental results, performed at 5 MHz, were obtained with a one-dimensional 128 elements array, using the tissue-mimicking phantoms also show that the proposed method provides better estimation results (within 3.04% of the actual value) with smaller estimation variances compared to the conventional methods (within 5.93%) for all cases considered.     

Structure and composition of secondary phase particles in cobalt-doped TiO2 films

The microstructural properties of secondary phase particles formed in epitaxial Co_xTi_1−xO₂ anatase thin films grown on (0 0 1)LaAlO₃ by a reactive RF magnetron co-sputter deposition are examined. These films exhibit ferromagnetic behavior in magnetization measurements, showing a M–H loop at room temperature with a saturation magnetization on the order of 0.7 μ_B /Co. X-ray photoemission spectrometry indicates that the Co cations are in the Co²⁺ valence state. Cross-section electron microscopy reveals that a significant fraction of the cobalt segregates into Co–Ti–O secondary phase particles. Selected area electron diffraction shows that the secondary phase particles are cobalt-rich anatase. While the cobalt is concentrated in the segregated particles, local energy dispersive spectrometry indicates some Co throughout the film.     

Antioxidant and binding properties of methanol extracts from indigo plant leaves

This study was conducted to clarify the effect of ultra-pressure treatment on the extraction of bioactive compounds from indigo plant leaves (Polygonum tinctorium Lour.) and on their properties. Leaves were harvested the in mid-August, 2013, from Naju City (Korea), and treated using two methods: ultra-pressure (550 MPa, 3 min) and hot-air (70°C, 24 h). Then, the leaves were ultrasonically extracted with methanol. The content of indirubin in leaves treated with ultra pressure and hot air was (535.55 ± 26.14) mg kg^?1 and (52.63 ± 6.45) mg kg^?1, respectively, and that of tryptanthrin was (165.55 ± 8.74) mg kg^?1 and (153.00 ± 7.62) mg kg^?1, respectively. Polyphenolic content in the leaves extract was (127.24 ± 13.67) mg kg^?1 after the ultrapressure and (88.22 ± 5.33) mg kg^?1 after the hot-air treatment. The content of flavonoids was (2298.67 ± 83.27) mg kg^?1 after the ultra-pressure and (3224.00 ± 21.45) mg kg^?1 after the hotair treatment. Di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH) radical scavenging activities of the indigo extract obtained by ultra-pressure and hot-air treatment methods at the concentration of 1 mg mL^?1 were (80.25 ± 0.73) % and (66.54 ± 2.35) %, respectively, and 2,2′-azinobis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging activities were estimated as (90.14 ± 0.79) % and (64.45 ± 8.97) %, respectively. The methanol leaf extract after ultra-pressure treatment exhibited higher binding properties to human serum albumin in comparison with catechin and conventional treatments. Consequently, it was assumed that the ultra-pressure treatment is an effective method for the extraction of bioactive compounds from indigo leaves.     

Development of new reference materials for the determination of cadmium,chromium, mercury and lead in polycarbonate

Reference materials for quantitative determination of Cd, Cr, Hg and Pb in polycarbonate were developed. Reference materials with two concentration level of elements were prepared by adding appropriate amounts of chemicals to a blank polycarbonate base material. It was shown that ten bottles with triplicate analysis are enough to demonstrate the homogeneity of these candidate reference materials. The statistical results also showed no significant trends in both short-term stability test for four weeks and long-term stability test for twelve months. The certification of the four elements was carried out by isotope-dilution-inductively coupled plasma mass spectrometry (ID-ICP-MS) with microwave-assisted digestion. Certification of candidate reference materials in a single laboratory was confirmed with interlaboratory comparison participated by a certain number of well-recognized testing laboratories in Korea. The certified values and expanded uncertainties (k = 2) for the candidate reference material with low level and the one with high level were (51.7 ± 2.1) mg kg⁻¹ Cd, (103.8 ± 2.9) mg kg⁻¹ Cd, (98.8 ± 4.5) mg kg⁻¹ Cr, (1004 ± 49.8) mg kg⁻¹ Cr, (107.4 ± 4.6) mg kg⁻¹ Hg, (1133 ± 50.7) mg kg⁻¹ Hg, (94.8 ± 3.7) mg kg⁻¹ Pb and (988.4 ± 53.6) mg kg⁻¹ Pb, respectively. The reference materials developed in this study demonstrated their suitability for the quality assurance in Cd, Cr, Hg and Pb analysis for the implementation of RoHS Directive.