ZnO/Al2O3 core-shell nanorod arrays: growth, structural characterization, and luminescent properties.

We report an aqueous chemical method to fabricate well-aligned ZnO/Al(2)O(3) nanocrystal (NC) core-shell nanorod arrays (NRAs). Structural characterization showed that the shell layers are composed of alpha-Al(2)O(3) nanocrystals. Photoluminescence measurements showed the enhancement of near-band-edge (NBE) emission of ZnO NRAs due to the presence of Al(2)O(3) NC shells. The Al(2)O(3) NC shell layer resulting in the flat-band effect near the ZnO surface leads to a stronger overlap of the wavefunctions of electrons and holes in the ZnO core, further enhancing the NBE emission. This approach should be very useful in designing many other core-shell NRAs for creating varieties of high-efficiency optoelectronic devices.

Equivalent-Time Electro-Optic Sampling by use of a Picosecond Laser with a Voltage-Controlled Optoelectronic Pulse-Delay Tuning Circuit.

We demonstrate a delay-line-free electro-optic sampling (EOS) system by using a novel ultrafast laser with a voltage-controlled pulse-delay tuning circuit (PDTC). The digital PDTC was designed as a substitute for a conventional optomechanical delay line in the EOS system, which facilitates the theoretical phase-tuning range of 4pi. The maximum delay time, tuning gain, and resolution of the PDTC are 3.6 ns (1.8 periods), 0.54 ns/V, and 0.2 ps, respectively. Arbitrary waveforms generated from microwave synthesizers, electrical pulse generators, and frequency prescalars are successfully sampled by use of this system, with a less than 8% deviation in the results.

Optoelectronic delay-time controller for laser pulses.

A dc-voltage-controlled optoelectronic delay line for continuous tuning of the relative delay time of an optical pulse train generated from a gain-switched laser diode is demonstrated. A maximum tunable range delay time of 3.9 ns ( approximately 2 periods) for optical pulses at a 500-MHz repetition rate is reported, which corresponds to a phase shift of as much as 4pi. The tuning responsivity and resolution of the current apparatus are 0.54 ps/mV and <0.2 ps, respectively. The measured timing fluctuation and long-term drift at any delay time are 0.13 ps and 20 fs/min, respectively. This scheme further permits the simultaneous phase tracking of the laser pulse train to unknown signals generated from the device under test.

Effects of cortisol on ion regulation in developing tilapia (Oreochromis mossambicus) larvae on seawater adaptation.

The yolk diameter of cortisol-treated tilapia (Oreochromis mossambicus) larvae, immersed in freshwater (FW) containing 10 mg L-1 cortisol from 48 h postfertilization to 12 d posthatching, was significantly larger than that of control larvae after 8 d of treatment, suggesting that inhibition on larval growth occurred only after a long-term treatment with cortisol. Tilapia embryos or larvae treated with 1-10 mg L-1 cortisol for 1-2 d and then transferred to 20-30 g L-1 seawater (SW) showed reduced cumulative larval mortality in SW compared with controls. Moreover, 4-5 d of cortisol treatments significantly diminished the degree of increase in larval body Na content after the transfer to SW. Significant effect of cortisol on body Na content of larvae occurred as early as 4-8 h after the transfer to SW, while no significant difference was found in the ouabain binding of yolk-sac epithelia between control and cortisol-treated larvae even 12 h after the transfer. Cortisol may be involved in the early phase of SW adaptation in developing larvae, and this mechanism may be achieved by other means than increasing the Na-K-ATPase of yolk-sac epithelia.

Role of specific acidic lipids on the reconstitution of Na(+)-dependent amino acid transport in proteoliposomes derived from Ehrlich cell plasma membranes.

The effect of acidic phospholipids on the activity of a Na(+)-dependent amino acid transporter (A system) from Ehrlich ascites cell plasma membranes was examined. Plasma membranes were solubilized in cholate/urea and reconstituted with Ba2(+)-precipitated asolectin (soybean phospholipid free of anionic phospholipids) replenished with different acidic phospholipids. In the absence of added acidic phospholipids, transport activity was very low. However, three acidic lipids [cardiolipin greater than phosphatidic acid (PA) greater than phosphatidylinositol] were capable of restoring transport activity (in the order given) to proteoliposomes made from Ba2(+)-precipitated asolectin, while other acidic phospholipids (phosphatidylserine and phosphatidylglycerol) were much less active in this respect. For restoration of optimal activity, PA containing at least one unsaturated fatty acyl moiety, particularly in the beta position, was required. PA containing only saturated fatty acids in the beta and gamma positions was largely inactive. No difference in restoration of function was observed on varying the saturated fatty acyl chain length in PA from 10 carbons to 18 carbons. The specific effects of PA on the A-system transporter were not shared by the Na(+)-independent amino acid exchange system (L system) or the glucose transport system. Treatment with poly(ethylene glycol) 8000 was shown to reduce the nonspecific permeability of the reconstituted proteoliposomes and to enhance Na(+)-dependent amino acid transport.

[Studies on ecology of Fasciolopsis buski and control strategy of fasciolopsiasis].

The development of eggs of Fasciolopsis buski requires oxygen and the eggs cannot survive anaerobic conditions. The eggs have some resistance to low temperature and can be maintained at 4 degrees C for 3 to 4 months; however, the eggs are killed at 50 degrees C in four hours. The presence of salts can influence the development time of the eggs and reduce their hatching rate. Encysted cercariae exist not only on aquatic plants, but also on the surface of the water. The number of encysted cercariae floating on the water surface is about 3.6% of that of the total encysted cercariae. By inquiring into the case history we found that 10.3-12.8% of the patients and 35.1-40% of the infested pigs were possibly infected by drinking water contaminated with encysted cercariae. The authors suggest the use of fermented silage to feed pigs instead of fresh aquatic green fodders to prevent infection in the animals. In addition, aquatic plants such as water chestnut should be boiled for 1 to 2 minutes before eating to kill the encysted cercariae on the plants.