Determination of 107 Pesticide Residues in Wolfberry with Acetate-buffered Salt Extraction and Sin-QuEChERS Nano Column Purification Coupled with Ultra Performance Liquid Chromatography Tandem Mass Spectrometry.

A multi-residue method for the determination of 107 pesticide residues in wolfberry has been developed and validated. Similar pretreatment approaches were compared, and the linearity, matrix effect, analysis limits, precision, stability and accuracy were validated, which verifies the satisfactory performance of this new method. The LODs and LOQs were in the range of 0.14-1.91 µg/kg and 0.46-6.37 µg/kg, respectively. The recovery of analytes at three fortification levels (10 µg/kg, 50 µg/kg, 100 µg/kg) ranged from 63.3-123.0%, 72.0-118.6% and 67.0-118.3%, respectively, with relative standard deviations (RSDs) below 15.0%. The proposed method was applied to the analysis of fifty wolfberry samples collected from supermarkets, pharmacies and farmers' markets in different cities of Shandong Province. One hundred percent of the samples analyzed included at least one pesticide, and a total of 26 pesticide residues was detected in fifty samples, which mainly were insecticides and bactericide. Several pesticides with higher detection rates were 96% for acetamiprid, 82% for imidacloprid, 54% for thiophanate-methyl, 50% for blasticidin-S, 42% for carbendazim, 42% for tebuconazole and 36% for difenoconazole in wolfberry samples. This study proved the adaptability of the developed method to the detection of multiple pesticide residues in wolfberry and provided basis for the research on the risks to wolfberry health.

High response organic deep ultraviolet photodetector with PEDOT:PSS anode.

We have fabricated an organic deep ultraviolet photodetector (PD) using PEDOT:PSS (PH 1000) as a transparent anode. NPB and PBD were employed as electron donor and acceptor, respectively. The PD exhibits a dark current of 0.0829 µA/cm(2) and a photocurrent of 85.3 µA/cm(2) at -12 V under 280 nm light illumination with an intensity of 0.488 mW/cm(2). A high response at 248-370 nm with its peak of 0.18 A/W at 280 nm and a detectivity of 1.1×10(12) cm Hz(1/2) W(-1) were achieved. The more detailed mechanism of harvesting high performance and the dependence of photocurrent density on illumination intensity are also discussed.

[Structural and optical characterization of ZnO thin films grown by plasma-assisted molecular beam epitaxy].

High-quality ZnO thin films were grown by plasma-assisted molecular beam epitaxy (P-MBE) on Al2 O3 (0001) substrate with a low temperature ZnO buffer layer. Structural and optical characterization were studied for ZnO thin films. Only a peak at (0002) were observed in the X-ray reflectivity (XRD) spectra with the full-width at half maximum (FWHM) value 0.18 degrees, and two peaks 1LO (579 cm(-1)) and 2LO (1 152 cm(-1)) were detected in the resonance Raman scattering spectra at room temperature. These results indicated that ZnO thin films had single orientation of c axis and high-quality of crystal wurtzite structure. The absorption of free-exciton and exciton-LO phonon appeared in the absorption spectra, which confirmed that the exciton state in the ZnO thin films were stable even at room temperature. And the energy spacing between these two peaks is 71.2 meV, corresponds to the longitudinal optical phonon energy of 71 meV of ZnO. Besides, from the photoluminescence spectra, no defect-related deep emission were observed, but just a remarkable free-exciton emission located at 376nm were obtained at room temperature, it proved that the ZnO thin films had high-quality but low density of defect.

[Effects of preparation parameters on the long lasting luminescence of ZnGa2O4].

Using high temperature solid state reaction method, ZnO and Ga2O3 with high purity as raw materials, different ZnGa2O4 samples were prepared at different molar ratios of raw materials and different temperatures. After excitation of the ZnGa2O4 samples by 254 nm UV lamps, obvious long lasting luminescence was detected for the first time, which showed two new long lasting luminescence peaks at 505 nm and 690 nm, respectively. And the relative intensity of the two peaks was effected by the preparation conditions such as molar ratio of the two raw materials and the sintering temperature. Less ZnO or higher temperature will strengthen the relative intensity of the 505 nm peak, while more ZnO or lower temperature will strengthen the relative intensity of the 690 nm peak. The origin of the two peaks was discussed based on some corresponding documents, and the conclusion is that the 505 nm peak comes from the 2E(A)-->4A2 transition of Ga3+ in a relatively distorted octahedral after some Zn2+ are substituted by Ga3+; and the 690 nm peak comes from the V0*--O2- transition after the singly charged ion oxygen vacancies appeare in the octahedral structure. The reasons why the preparing conditions can affect the relative peak intensity of the two peaks were also discussed. Less ZnO will cause Zn2O vacancies in the structure and more Ga3+ will occupy the Zn2+ positions, then will form distorted octahedral, and then the transition from energy level 2E(A) to (4)A2 of Ga3+ will cause the 505 nm peak to be dominant. On the other hand. too much ZnO will form oxygen vacancies, which will cause the 690 nm peak to be dominant. Higher temperature will cause more evaporation of ZnO and then relative less ZnO, and lower temperature will cause less evaporation of ZnO and then more oxygen vacancies. These conclusions are corresponding with the origin of the two peaks discussed before.

[Study on the property of CBD-CdS thin films].

CdS thin films were prepared by chemical bath deposition (CBD) at 90 'C. The influence of annealing and CdCl2 treatment on CBD-CdS thin film was studied. XRD and SEM were used to study the crystal structure and surface morphology ofthe films. The untreated CBD-CdS films had poor crystallinity; the CdS thin film made with annealing treatment had cubic crystallinity but small grain size. After the CdCl2 treatment, these films recrystallized to the hexagonal phase, resulting in a better crystallinity, and smooth surface morphology. Optical properties were studied by absorption spectrum. The energy gap of the films was found to decrease by annealing, and the CBD-CdS made with CdCl2 treatment had a lower density of planar defects. In conclusion, the CdCl2 treatment can improve the properties of the CdS thin films.

[Study of luminescence properties of nano-size ZnO embedded in SiO2 layer grown by radio-frequency magnetron sputtering].

Nano-size ZnO embedded in SiO2 layers were grown by radio-frequency magnetron sputtering. Absorption spectra and PL spectra were employed to study the optical character of the samples at room temperature. Absorption spectra blue-shifted when the size of nano-meter ZnO decreased, which indicated that quantum size effect became stronger with decreasing the size of ZnO. PL spectra show two peaks at about 387 and 441 nm, respectively. It was concluded that the UV emission originates from the radiative recombination of free-exciton, and the blue emission is due to the electron transition from donor levels of oxygen vacancies to the top of valence band. The origin of the two peaks is demonstrated by time-resolved spectra and luminescence decay curve.

[Influence of novel surface treatment of ITO anodes on the performance of OLED].

The influences of surface treatments of indium-tin-oxide (ITO) anodes on the performance of OLED devices were investigated. This surface treatment is mechanical processes using a novel nanometer powder. Their surface morphology was measured by scanning using an AFM (atomic force microscope). The number and size of spike was reduced and regulation of ITO was enhanced; brightness and efficiency of devices were obviously increased. This novel way for ITO surface treatment by mechanical processes was proven to be effective.

[Luminescence properties of rare earth complexes Tb(BSA)4].

A new rare earth complex Tb(BSA)4 was synthesized and studied. Pure green and narrow band emission was generated from the device with structure ITO/PVK:Tb(BSA)4 /Alq3 /LiF/Al, where PVK was used to improve the film-formation and hole-transport property of the Tb(BSA)4. The absorption mechanism, and the photoluminescence and electroluminescence mechanisms are discussed. It has been proved that there exists energy transfer from PVK to Tb(BSA)4 and the mechanisms of photoluminescence and electroluminescence are different. The effect of different ratios of PVK on the device characteristics is also studied.

[Preparation of anodic Al2O3 films on SiO2 substrate and their photoluminescence properties].

300 nm thick aluminum films were deposited on SiO2 substrates by heat evaporation. At 0 degrees C, 40 V DC voltage, the authors successfully prepared high density Al2O3 films by anodic oxidation on SiO2 substrates with 15 wt% H2SO4 as electrolyte, and AFM was employed to study the film surface morphology. At room temperature the authors measured the photoluminescence spectrum of Al2O3 films prepared at different anodic voltages excited by Xe lamp. In addition, the authors monitored their excitation spectra of different emission peaks, and the authors found that the relative emission intensity gets weaker and shifts to lower energy at higher anodic voltage. At 40 V anodic voltage the authors observed new 356 nm ultraviolet emission, which has the same 210 nm excitation emission. Based on the discussion of the relative intensity of the PL spectra of anodic alumina at different voltages, the authors suggest that F and F+ oxygen vacancy defects were responsible for the observed 356 and 386 nm ultraviolet photoluminescence from Al2O3 anodic film at 40 V voltage.

[Photovoltaic character of organic EL devices MEH-PPV/Alq3].

An organic photovoltaic(PV) cell, ITO/MEH-PPV/Alq3/LiF/Al, was fabricated. The MEH-PPV and Alq3 are the electron-acceptor and donor in the cell, respectively. The respond region matchs the adsorption of Alq3 film. Under UV light with 0.5 mW x cm(-2), the cell shows a short-circuit current of 2.4 microA x cm(-2), open-circuit voltage of 2.6 V, a fill factor of 0.71, and a power conversion efficiency of 0.9%. It was found that the PV cell indicates electroluminescence (EL) performance and could emit orange light at DC voltage. The maximum luminance is about 1 000 cd x cm(-2) at 15 V.

[Photoluminescent and electroluminescent properties of a new rare earth terbium complex].

Pure green and narrowbandwidth emission from an organic electroluminescent device was presented by using arare earth terbium (III) complex as the emissive layer. The structure of the device was ITO/PVK/Tb/PBD/LiF/Al. It was proved that this new kind of rare earth complex has excellent photoluminescent and electroluminescent properties. The electroluminescent spectrum of the device was very similar to that of the terbium (III) complex film. The electroluminescent mechanism of the device was proposed by measuring and analyzing the spectra and electroluminescent property of the device. It is proposed that the excited carriers of PVK and PBD were captured by Tb3+ and light was emitted when the electrons and holes recombined at Tb3+.

[Properties of the stimulated emission in the ZnO thin film].

ZnO thin film is a promising material for short-wave laser and LED etc, due to its high excition binding energy, intense stimulated emission, low lasing threshold, and high working temperature. ZnO thin films were prepared by laser molecular beam epitaxy (L-MBE) in our work. At room-temperature we reported the measurements of absorption spectra and emission spectra of ZnO thin films excited by various optical pumping intensities. High structural perfection of our sample was shown in these figures. We studied the properties and mechanism of stimulated emission in ZnO thin films. The relation between emission intensity and pumping intensity was obtained. Time behaviors of the stimulated emission under relatively high pumping intensity, spontaneous emission, and laser pulses were compared, and hence the stimulated emission of ZnO thin films was proved.