A Miniaturized and Highly Sensitive "Windmill" Three-Channel Fluorescence Detector for Simultaneous Detection of Various Mycotoxins.

A novel "windmill" three-channel light-emitting diode induced fluorescence detector (LED-IF) was proposed to maximize the excitation efficiency and fluorescence collection efficiency. Compared with the typical collinear arrangement, the fluorescence intensity of the three channels was increased by 7.85, 3.88, and 2.94 times, respectively. The compact shaping optical path was designed to obtain higher excitation efficiency and a lower background stray light effect caused by high divergence angle high-power ultraviolet (UV)-LEDs simultaneously, which increased the sensitivity of three channels by 4.6 to 5.7 times. It was found that using a photodiode (PD) with a flat window and a larger photosensitive surface can collect the Lambertian emission fluorescence in the flow cell more efficiently, increasing the signal-to-noise ratio of each channel 1.3 to 1.8 times. The limits of detection (LODs, 3 times peak-peak noise) of aflatoxin B2 (AFB2), ochratoxin (OTA), and zearalenone (ZEN) were 0.33, 1.80, and 28.2 ng/L, respectively. Finally, six mycotoxins were analyzed simultaneously by the detector coupling with HPLC. The results showed that the sensitivity of the detector was at the best level to date, which was better than that of the top commercial fluorescence detectors (FLDs). The developed detector has the advantages of having small volume, low cost, and long lifetime and being robust, which has wide application and market prospects.

Facile fluorescence detection of malachite green in fish using molecularly imprinted polymers doped CdTe quantum dots based system.

Malachite green (MG) possesses high toxicity, therefore, the detection of MG in fish tissues is of vital importance. A novel core-shell MIPs doped CdTe quantum dots coated silica nanoparticles (CdTe-MIP/SiO2 NPs) were synthesized via a simple one-pot strategy. The materials were characterized carefully. The resulting CdTe-MIP/SiO2 NPs were coated on the thin layer chromatography plate, and coupled with miniaturized fluorimeter for fluorescence detection of MG in fish samples. The resulting CdTe-MIP/SiO2 NPs based system possessed good linearity (0.01 âˆ¼ 20 µmol/L), high recoveries (98.36 %∼101.45 %) and low detection limit (3.7 nmol/L) for MG. Furthermore, CdTe-MIP/SiO2 NPs based system were employed to measure fish samples spiked with MG, meanwhile, HPLC was utilized to evaluate the accuracy and reliability. And the paired t-test was conducted to evaluate differences between fluorescence method and HPLC, P > 0.05 means no significant difference was observed, the results demonstrated that both fluorescence method and HPLC are suitable for MG analysis.

A 96-well plate UV fluorometer based on micro fluorescence detector array and dynamic zero correction algorithm.

A 96-well plate UV fluorometer was developed and evaluated. Eight micro fluorescence detectors close to each other were used as detector array for 8 channels. Each detector employed an UV light emitting diode (LED) as light source and a photodiode (PD) with an amplifier circuit as optoelectronic detector. The optical paths of the detectors were designed by ray tracing method to avoid crosstalk between wells. Simultaneously scanning and detecting of 8 channels saves scanning time and improves detection efficiency. The scanning time of the 96-well plate was about 80 s. A dynamic zero correction algorithm was proposed to solve the problem of measurement accuracy reduction caused by the background fluorescence differences between plates and wells under irradiation of UV light. The measurement repeatability (RSD) for 1 µg/L 7-Diethylamino-4-methylcoumarin sample was 2.25%. Compared with the fixed zero correction method, the limit of detection (LOD), measurement repeatability, and average relative error were improved by 3.3, 2.7, and 4.5 times, respectively. The proposed method is robust and can be applied to different analysis systems. The developed fluorometer has great potential in high-throughput rapid detection of food safety and life sciences.

On the legal status of marine fishery resources: From the perspectives of international fishery law.

The legal status of marine fishery resources is analyzed from a spatial perspective: States have the right for their nationals to engage in fishing activities in the corresponding maritime areas based on the sovereignty, sovereign rights, the principle of freedom of the high seas as well as the principle of the common heritage of mankind of the Area under the 1982 United Nations Convention on the Law of the Sea (UNCLOS). Meanwhile, the legal status of marine fishery resources is analyzed from two aspects in terms of contents: the legal regime of exploitation and utilization of marine fishery resources and the legal regime of conservation and management of marine fishery resources. The transformation of marine fishery resources from natural resources to individual catches involves the regime of ownership. There is no specific regime of ownership regarding marine fishery resources under UNCLOS or other international legal instruments, which should be stipulated by domestic laws.

Elliptical polarization favors long quantum orbits in high-order above-threshold ionization of noble gases.

We demonstrate the significant role of long quantum orbits in strong-field atomic processes by investigating experimentally and theoretically the above-threshold ionization spectra of noble gases in intense elliptically polarized laser pulses. With increasing laser ellipticity, the yields of different energy regions of the measured electron spectrum in high-order above-threshold ionization drop at different rates. The experimental features can be reproduced by a theoretical simulation based on quantum-orbit theory, revealing that increasing ellipticity favors the contributions of the long quantum orbits in the high-order above-threshold ionization process.

Ionization suppression of diatomic molecules in an intense midinfrared laser field.

Diatomic molecules (e.g., O(2)) in an intense laser field exhibit a peculiar suppressed ionization behavior compared to their companion atoms. Several physical models have been proposed to account for this suppression, while no consensus has been achieved. In this Letter, we aim to clarify the underlying mechanisms behind this molecular ionization suppression. Experimental data recorded at midinfrared laser wavelength and its comparison with that at near-infrared wavelength revealed a peculiar wavelength and intensity dependence of the suppressed ionization of O(2) with respect to its companion atom of Xe, while N(2) behaves like a structureless atom. It is found that the S-matrix theory calculation can reproduce well the experimental observations and unambiguously identifies the significant role of two-center interference effect in the ionization suppression of O(2).

[Serum antibody response and Hantavirus RNA sequencing in patients with hemorrhagic fever renal syndrome in Yantai areas].

OBJECTIVE: To understand antibody responses to and RNA sequences of Hantavirus in patients with hemorrhagic fever renal syndrome (HFRS) in Yantai areas and to demonstrate the type of the prevalent viruses caused HFRS. METHODS: Serum specimens collected at acute and convalescent stages from 90 patients with HFRS and IgM and IgG antibodies against Hantavirus were detected with ELISA, and cross plaque reduction neutralizing tests were performed to detect neutralizing antibody. Viral RNA was extracted from the patients? sera by using Trizol method and nested PCR was utilized to amplify the specific segments of the viral cDNA and the products of the PCR were TA cloned and then the nucleotide sequences were determined. RESULTS: The IgM antibody was positive in 82.2% (88/107) of the patients while the IgG antibody was positive in 85.7% (66/77) of the patients. Both the serologic and sequence analyses demonstrated that the epidemic of HFRS in Yantai areas was caused by mixed types of Hantavirus. The prevalent strains of Hantavirus had higher homology with the strains isolated in Korea than with those isolated previously in China. CONCLUSIONS: The serologic and sequencing analyses indicated that the epidemic of HFRS in Yantai areas was caused by mixed types of Hantavirus dominated by type SEO.