Effects of roasting,powdering and storing irradiated soybeans on hydrocarbon detection for identifying post-irradiation of soybeans

Hydrocarbons, which are produced by irradiation of lipid-containing foods, were analyzed in irradiated soybeans, which were roasted, powdered and stored, to determine whether these treatments affect hydrocarbon detection for identifying post-irradiation of soybeans. Soybeans were irradiated (Irr), irradiated and roasted (Irr–Rst), roasted and irradiated (Rst–Irr), irradiated, roasted and powdered (Irr–Rst–Pwd), and roasted, powdered and irradiated (Rst–Pwd–Irr). They were stored at refrigerated or room temperature for 30 weeks. Oils were extracted using hexane and Na₂SO₄. Hydrocarbon fraction was separated through a Florisil column and analyzed using GC. Hydrocarbons 17:2, 16:3, 17:1 and 16:2 were not detected in non-irradiated soybeans and soybean powder, but they were detected in those irradiated at 0.5 kGy or higher. The levels of the hydrocarbons increased with dose. The hydrocarbon levels in the Irr–Rst, Rst–Irr, and Irr–Rst–Pwd soybeans were little different from those in the Irr soybeans. Hydrocarbon detection in the Rst–Pwd–Irr soybean powder showed a slightly different pattern from those in the other treatments. Hydrocarbon levels in the soybean and soybean powder samples stored at refrigerated temperature for 30 weeks changed little, compared to initial samples. The hydrocarbon detection patterns in the samples stored at room temperature for 30 weeks were similar to the initial and refrigerated samples with slightly lower detection levels in the room-stored samples.     

Correlation of measured excess enthalpies of binary systems composed of n-alkane+1-alkanol

The excess enthalpies of the binary mixture composed of n-alkane (n-octane, n-nonane, n-decane) and 1-alkanol (ethanol, 1-propanol, 1-butanol) have been measured by using a flow-type isothermal microcalorimeter (model CSC 4400, Calorimetry Science Corp., USA) at 313.15 K under atmospheric pressure. The measured excess enthalpy data were correlated by the Redlich-Kister equation and the nonrandom lattice fluid with hydrogen bonding (NLFHB) equation of state. Hydrogen bonding type specific parameters were introduced in the NLF-HB equation of state framework, and the effects of those parameters were investigated for excess enthalpy calculations. With two adjustable temperature-dependent interaction parameters, the NLF-HB equation represents the excess enthalpies for nine binary systems qualitatively. This article is dedicated to Professor Chul Soo Lee in commemoration of his retirement from Department of Chemical and Biological Engineering of Korea University.     

Correlative High‐Resolution Mapping of Strain and Charge Density in a Strained Piezoelectric Multilayer

A key to strain engineering of piezoelectric semiconductor devices is the quantitative assessment of the strain‐charge relationship. This is particularly demanding in current InGaN/GaN‐based light‐emitting diode (LED) designs as piezoelectric effects are known to degrade the device performance. Using the state‐of‐the‐art inline electron holography, we have obtained fully quantitative maps of the two‐dimensional strain tensor and total charge density in conventional blue LEDs and correlated these with sub‐nanometer spatial resolution. We show that the In_0.15Ga_0.85N quantum wells are compressively strained and elongated along the polar growth direction, exerting compressive stress/strain on the GaN quantum barriers. Interface sheet charges arising from a polarization gradient are obtained directly from the strain data and compared with the total charge density map, quantitatively verifying only 60% of the polarization charges are screened by electrons, leaving a substantial piezoelectric field in each In_0.15Ga_0.85N quantum well. The demonstrated capability of inline electron holography provides a technical breakthrough for future strain engineering of piezoelectric optoelectronic devices.     

Formation of self-organized Zircaloy-4 oxide nanotubes in organic viscous electrolyte via anodization

This work reports the formation of self-organized Zircaloy-4 (Zr-4) oxide nanotubes in viscous organic ethylene glycol (EG) electrolyte containing a small amount of fluoride salt and deionized (DI) water via an electrochemical anodization. The structure, morphology, and composition of the Zr-4 oxide nanotubes were studied using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), EDX, and XPS. SEM results showed that the length of the nanotubes is approximately 13 μm, and TEM results showed that the inner diameter of the Zr-4 oxide nanotubes is approximately 20 nm with average wall thickness of approximately 7 nm. XRD and selected area electron diffraction pattern (SAED) results confirmed that the as-anodized Zr-4 oxide nanotubes have cubic crystalline structure. Both cubic and monoclinic phases were found after annealing of Zr-4 oxide nanotubes. The tubular structure morphology of Zr-4 oxide nanotubes did not remain intact after annealing which is attributed to the elimination of F species from the annealed nanotubes.     

Efficient white organic light-emitting diodes with mixed electron transporting layers

The authors demonstrated phosphorescent white organic light-emitting diodes (PHWOLED) with mixed electron transporting layers (M-ETL) using 4,7-diphenyl-1,10-phenanthroline (BPhen)/4,4′-bis (carbazol-9-yl)biphenyl (CBP). The M-ETL PHWOLED exhibited the optimum balance of holes and electrons, owing to the low electron mobility of the CBP M-ETL. The optimized PHWOLED showed a peak current efficiency of 16.85 cd/A and a peak external quantum efficiency of 7.32%.     

Directed self-assembly of organic semiconductors via confined evaporative capillary flows for use in organic field-effect transistors

We fabricated well-defined 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-PEN) crystal arrays for use in electronic applications via a simple but effective method, the confined evaporative capillary flow (CEC) method. This has been accomplished by systematically controlling the contact line pinning at the edge of glass stylus and the outward hydrodynamic flow within the drying droplet with various processing solvents and surface properties of the substrate during solidification. We found that after CEC coating of TIPS-PEN solution dissolved into toluene onto SiO₂ surface, ribbon-shaped TIPS-PEN crystals were well developed with a width of 20–100 μm and length of 300 μm – 2 mm, which is presumably owing to optimized capillary evaporation. Specifically, TIPS-PEN crystals present highly preferred crystal orientation along the (l 0 0) axis, which can lead to efficient charge transport in a lateral direction. Thus, TIPS-PEN field-effect transistors (FETs) exhibited a good hole mobility of 0.72 cm²/Vs.