Pressure-assisted field-amplified sample injection with reverse migrating micelles for analyzing trace steroids in MEKC

This paper describes a novel method that applies pressure-assisted field-amplified sample injection with reverse migrating micelles (PA-FASI-RMM) for the online concentration of neutral analytes in MEKC with a low-pH BGE. After injection of a plug of water into the separation capillary, negative voltage and positive pressure were simultaneously applied to initialize PA-FASI-RMM injection. The hydrodynamic flow generated by the positive pressure compensated the reverse EOF in the water plug and allowed the water plug to remain in the capillary during FASI with reverse migrating micelles (FASI-RMM) to obtain a much longer injection time than usual, which improved stacking efficiency greatly. Equations describing this injection mode were introduced and were supported by experimental results. For a 450-s online PA-FASI-RMM injection, three orders of magnitude sample enhancement in terms of peak area could be observed for the steroids and an achievement of detection limits was between 1 and 10 ng/mL.

Hematological and plasma biochemical responses of crucian carp (Carassius auratus) to intraperitoneal injection of extracted microcystins with the possible mechanisms of anemia

Alterations in hematological indices such as decreases in blood cell counts (RBC), hematocrit (Ht) and hemoglobin (Hb) concentrations are key symptoms of anemia. However, few experiments were conducted to examine changes in hematological indices of fish exposed to microcystins that are believed to be fatal to circulatory systems of vertebrates. An acute toxicological experiment was designed to study hematological changes of crucian carp injected intraperitoneally (i.p.) with extracted microcystins at two doses, 50 and 200 mu g MC-LReqkg(-1) body weight. After being i.p. injected with microcystins, the fish exhibited behavioral abnormity. There were significant decreases in RBC in the high-dose group, and in Ht and Hb concentrations in both dose groups, while erythrocte sedimentation rate (ESR) significantly increased, indicating the appearance of normocytic anemia. There were no prominent changes in the three red cell indices, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH,), and mean corpuscular hemoglobin concentration (MCHC). Increases in blood urea nitrogen (BUN) and creatinine (CR) in both dose groups suggest the occurrence of kidney impairment. Alteration in blood indices was reversible at the low dose group. Conclusively, anemia induced by kidney impairment was a key factor to cause abnormity of swimming behaviors and high mortality of crucian carp. (c) 2007 Elsevier Ltd. All rights reserved.

An improved method for the extraction of low molecular weight organic acids in variable charge soils

Due to specific adsorption to variable charge soils, low molecular weight organic acids (LMWOAs) have not been sufficiently extracted, even if common extractants, such as water and 0.1 M sodium hydroxide (NaOH), were employed. In this work, the method for extracting LMWOAs in soils with 0.1 M NaOH was improved for variable charge soils; e.g. 1.0 M potassium fluoride (KF) with pH 4.0 was applied as an extractant jointed with 0.1 M NaOH based on its stronger ability to change the electrochemical properties of variable charge soils by specific adsorption. With the proposed method, the recoveries of oxalic, tartaric, malic, citric and fumaric acids were increased from 83 4, 93 1, 22 2, 63 +/- 5 and 84 +/- 3% to 98 +/- 2, 100 +/- 2, 85 +/- 2, 90 +/- 2 and 89 +/- 2%, respectively, compared with NaOH alone. Simultaneously, the LMWOAs in Agri-Udic Ferrosol with field moisture were measured with a satisfactory result.

Simultaneous determination of chromium(VI) and chromium(III) of bioavailable fraction in bottom mud by flow injection-atomic absorption spectroscopy

A rapid and sensitive method for separation and determination of Cr(VI) and Cr(III) in bottom mud of lake by flow injection on-line preconcentrtion system and GFAAS was developed. The available Cr(VI) and Cr(III) were extracted by HOAc or EDTA + NH4 NO3 and adsorbed simultaneously by an anion and a cation resin microclummn and then eluted simultaneously by 2 mol/L NH4 NO3 + 0.05 mol/L ascorbate and 2 mol/L H2SO4, respectively. The elution was performed for 50 s after adsorption for 2 min, and the efficiencies of elution were 85.4% - 94.8% and 96.7% - 106% for Cr(VI) and Cr(M) respectively. The detection limits of the method were 0.9 mu g/L and 2.7 mu g/L with relative standard deviations of 3.5% and 6.4% for the determination of Cr(VI) and Cr(III) in sample, respectively.

Effects of intraperitoneal injection of cortisol on nonspecific immune functions of Ctenopharyngodon idella

After grass carps Ctenopharyngodon idellus were injected with cortisol, with (CBC) and without (C) a cocoa butter carrier, the effects of both slowly and rapidly acting exogenous cortisol oil their non-specific immune functions were investigated. On the one hand, after injection with CBC, the cortisol concentration and lysozyme activity in fish serum were enhanced and were sustained at high levels for a long period (30 days). The killing activity in the serum declined with time, and phagocytosis of head kidney macrophages diminished significantly (P < 0.05 or P < 0.01). The leukocrit values in the high dose group (31-8 mg cortisol fish(-1)) increased over time, however, with the maximum average being 5.6% at day 30. The spleen mass index in the high dose group was 0.93 x 10(-3) after 30 days, notably lower (P < 0.05) than that in the control group. In addition, a decrease in resistance to Aeronionas hydrophilo infection in cortisol-treated fish was shown, with the final cumulative mortalities being 54.5 and 66.7% in the low and high dose groups, respectively. On the other hand, there was a decrease in both serum cortisol concentration and lysozyme activity of the experimental fish within 2 weeks after injection with C, where plasma bactericidal activities in the high dose group (31-8 mg cortisol fish(-1)) were remarkably lower (P < 0.01) than those in the control group at each sampling, but were increased slightly over time. The results of which were different from those in the CBC trial. Phagocytic activity of head kidney macrophages and spleen mass index decreased significantly (P < 0.05), while there were increases in leukocrit value and cumulative mortality due to A. hydrophila. The results of which were similar to those in the CBC trial. This study indicated that the injection of cortisol depressed the non-specific immune functions of the grass carp and increased its susceptibility to disease. (c) 2005 The Fisheries Society of the British Isles.

Spin injection in the multiple quantum-well LED structure with the Fe/AlO (x) injector

A spin-injection/-detection device has been fabricated based on the multiple quantum well light emitting diode (LED) structure. It is found that only a broad electroluminescence (EL) peak of a full width at half maximum of 8.6 nm appears at the wavelength of 801 nm in EL spectra with a circular luminescence polarization degree of 18%, despite PL spectra always show three well resolved peaks. The kinetic energy gained by injected electrons and holes in their drift along opposite directions broadens the EL peak, and makes three EL peaks converge together. The same process also destroys the injected spin polarization of electrons mainly dominated by the Bir-Aronov-Pikus spin relaxing mechanism.

Theoretical analysis and experimental study of the space-charge-screening effect in uni-traveling-carrier photodiode

A new optimized structure of an UTC (uni-traveling-carrier) photodiode is developed and epitaxied by metal-organic chemical vapor deposition. We fabricated a UTC photodiode of 30 mu m in diameter. Theoretical simulation based on drift-diffusion model was used to analyze the space-charge-screening effect in UTC photodiode primarily in two aspects: the carrier concentrations and the space electric field. The simulation results were generally in agreement with the experimental data.

The performance enhancement in organic light-emitting diode using a semicrystalline composite for hole injection

A semicrystalline composite, 3, 4, 9, 10 perylenetetracarboxylic dianhydride (PTCDA) doped N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (NPB), has been fabricated and characterized. An organic light-emitting diode using such a composite in hole injection exhibits the improved performance as compared with the reference device using neat NPB in hole injection. For example, at a luminance of 2000 cd/m(2), the former device gives a current efficiency of 2.0cd/A, higher than 1.6cd/A obtained from the latter device. Furthermore, the semicrystalline composite has been shown thermally to be more stable than the neat NPB thin film, which is useful for making organic light emitting diodes with a prolonged lifetime.

Enhanced modulation bandwidth of a Fabry-Perot semiconductor laser subject to light injection from another Fabry-Perot laser

Variations in optical spectrum and modulation band-width of a modulated Fabry-Perot (FP) semiconductor laser subject to the external light injection from another FP Laser is investigated in this paper. Optimal wavelength matching conditions for two FP lasers are discussed. A series of experiments show that two FP lasers should have a central wavelength overlapping and a mode spacing difference of several gigahertz. Under these conditions both the magnitude and phase frequency responses can be improved significantly.

Organic light emitting diodes using magnesium doped organic acceptor as electron injection layer and silver as cathode

Organic light emitting diodes employing magnesium doped electron acceptor 3, 4, 9, 10 perylenetetracarboxylic dianhydride (Mg: PTCDA) as electron injection layer and silver as cathode were demonstrated. As compared to Mg: Ag cathode, the combination of the Mg: PTCDA layer and silver provided enhanced electron injection into tris (8-quinolinolato) aluminium. The device with 1: 2 Mg: PTCDA and Ag showed an increase of about 12% in the maximum current efficiency, mainly due to the improved hole-electron balance, and an increase of about 28% in the maximum power efficiency, as compared to the control device using Mg: Ag cathode. The properties of Mg: PTCDA composites were studied as well.

Organic light-emitting diodes with magnesium doped CuPc as an efficient electron injection layer

Bright organic electroluminescent devices are developed using a metal-doped organic layer intervening between the cathode and the emitting layer. The typical device structure is a glass substrate/indium-tin oxide (ITO)/copper phthalocyanine (CuPc)/NN'-bis-(1-naphthl)-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB)/Tris(8-quinolinolato) aluminum(Alq(3))/Mg-doped CuPc/Ag. At a driving voltage of 11 V, the device with a layer of Mg-doped CuPc (1:2 in weight) shows a brightness of 4312 cd/m(2) and a current efficiency of 2.52 cd/A, while the reference device exhibits 514 cd/m(2) and 1.25 cd/A.

Reduced dynamics with renormalization in solid-state charge qubit measurement

Quantum measurement will inevitably cause backaction on the measured system, resulting in the well-known dephasing and relaxation. In this paper, in the context of solid-state qubit measurement by a mesoscopic detector, we show that an alternative backaction known as renormalization is important under some circumstances. This effect is largely overlooked in the theory of quantum measurement.

Injection locked Fabry-Perot laser diodes for WDM passive optical network spare function

In this paper, a protection scheme for transmitters in wavelength-division-multiplexing passive optical network (WDM-PON) has been proposed and demonstrated. If any downstream transmitter encounters problems at the central office (CO), the interrupted communication can be restored immediately by injecting a Fabry-Perot laser diode (FP-LD) with the upstream lightwave corresponding to the failure transmitter. Compared with the conventional methods, this proposed architecture provides a cost-effective and reliable protection scheme employing a common FP-LD. In the experiment, a 1 36 protection capability was implemented with a 2.5 Gbit/s downstream transmission capability. (C) 2009 Elsevier B.V. All rights reserved.

Crystallographic plane tuning of charge and spin transport in semiconductor quantum wires

We investigate theoretically the charge and spin transport in quantum wires grown along different crystallographic planes in the presence of the Rashba spin-orbit interaction (RSOI) and the Dresselhaus spin-orbit interaction (DSOI). We find that changing the crystallographic planes leads to a variation of the anisotropy of the conductance due to a different interplay between the RSOI and DSOI, since the DSOI is induced by bulk inversion asymmetry, which is determined by crystallographic plane. This interplay depends sensitively on the crystallographic planes, and consequently leads to the anisotropic charge and spin transport in quantum wires embedded in different crystallographic planes.