Ultrasonic extraction and determination of cyanuric acid in pet food

Cyanuric acid is attracting more attention due to its potential toxicity. In the present work, an ultrasonic extraction method in combining with high-performance liquid chromatography (HPLC) was proposed for the determination of cyanuric acid in pet food. Among different solvents, methanol was found to be the best one as the extractant due to the strong polarity of cyanuric acid and the interferences in the pet food. The ultrasonic energy permitted an extraction time as less as 30 min, which was much shorter than 240 min required in the magnetic-stirring extraction. Under the selected HPLC conditions, the HPLC method could respond linearly with cyanuric acid at concentrations from 0.008 to 4.0 mg mL^?1 with a detection limit of 0.002 mg mL^?1. In the analysis of practical spiked pet food samples, the new method yielded satisfactory results.     

Studies on silicon-on-insulator-multilayer structures prepared by epitaxial layer transfer

The silicon-on-insulator-multilayer (SOIM) structures were proposed and successfully fabricated by epitaxial layer transfer technology. The properties of the structures were investigated using cross-sectional transmission electron microscopy (XTEM) and spreading resistance profiling. Experimental results show that the buried Si₃N₄ layer is amorphous and the new SOIM sample has good structural and electrical properties. The new SOIM device has been verified in two-dimensional device simulation and indicated that the new structures reduce device self-heating and increase the drain of the SOI MOSFET.     

Microstructure and broadband dielectric properties of Zn2SiO4 ceramics with nano-sized TiO2 addition

Zn₂SiO₄ ceramics with nano-sized TiO₂ addition (ZST) were synthesized by conventional solid state method. The association between the new composite's microstructures and dielectric properties reveals that reduced pores, increased density and average grain sizes with increasing sintering temperatures, have contributed to the increased permittivities at kHz and microwave bands; the decrease of the permittivities at 1275 °C is due to the form of twin planes. At the terahertz band, the competition of generating oxygen vacancies and forming them into twin crystallographic shear planes dominates the change of permittivities: the crystallographic shear planes decrease the permittivity at the sintering temperature 1225 °C and 1250 °C, and the high-rate generation of oxygen vacancies at 1275 °C increases the permittivities. The ZST ceramics demonstrate stable permittivity and low dielectric losses (<10^–3 from 10 kHz to microwave band; and <10^–2 at THz range); and the temperature coefficient of resonant frequency is optimized to close zero. These advanced dielectric properties and low sintering temperature (<1300 °C) provide the ZST ceramics great potential in designing microwave and THz devices.     

Highly sensitive C2H2 gas sensor based on Ag modified ZnO nanorods

The sliver (Ag) modified zinc oxide (ZnO) nanorods were successfully obtained with a simplified and environmentally friendly solvothermal method. Materials characterization indicated that the metallic Ag was located on the outside of ZnO nanorods after annealing. In comparison with ZnO nanorods, Ag modified ZnO (Ag–ZnO) nanorods exhibited a considerably enhanced response to C₂H₂. The response of the 3 at% Ag–ZnO based sensor operating at 175 °C is 539 (R_a/R_g), which is the highest value among all the sensors in detecting 100 ppm C₂H₂. The Ag–ZnO based sensors exhibited fast response speed, lower operation temperature and higher selectivity.     

Sn-containing Si3N4-based composites for adaptive excellent friction and wear in a wide temperature range

Ceramic design based on reducing friction and wear-related failures in moving mechanical systems has gained tremendous attention due to increased demands for durability, reliability and energy conservation. However, only few materials can meet these requirements at high temperatures. Here, we designed and prepared a Sn-containing Si₃N₄-based composite, which displayed excellent tribological properties at high temperatures. The results showed that the friction coefficient and wear rate of the composites were reduced to 0.27 and 4.88 × 10^?6 mm³ N^?1 m^?1 in air at 800 °C. The wear mechanism of the sliding pairs at different temperatures was revealed via detailed analyses of the worn surfaces. In addition, the tribo-driven graphitization was detected on the wear surfaces and in the wear debris, and the carbon phase was identified by SEM, TEM, and Raman spectrum.     

Cold sintering assisted CaF2 microwave dielectric ceramics for C-band antenna applications

A cold sintering process is adopted to pre-densify CaF₂ ceramics from 85.7% at 300 MPa to 91.7% at 750 MPa. Subsequent post-annealings at 1000–1150 °C lead to further improvements in densification, where great enhancements of grain size and crystallinity are also observed from the scanning and transmission electron micrographs. Significant advances in Qf values are achieved in the post-annealed CaF₂ ceramics. The optimum Qf value (80,522 GHz) is achieved after cold sintering at 750 MPa and post-annealing at 1000 °C, which is three times higher than the conventional sintered one at 1000 °C (26,448 GHz). Moreover, the obtained low-ε_r (5.9–6.5) of CaF₂ ceramics suggests broad application prospects in the high-band microwave communications. A microstrip patch antenna is fabricated using the CaF₂ ceramics as the substrate, which operates at 7.89 GHz in the C-band, with an S₁₁ of ?13.4 dB, simulated high gain and efficiency of 6.41 dBi and ?0.56 dB, respectively.     

Construction of self-sensitized LiErF4: 0.5% Tm3+@LiYF4 upconversion nanoprobe for trace water sensing

Nano Research - LiErF4 was commonly used as a dipolar-coupled antiferromagnet, and was rarely considered as a luminescent material. Herein, we achieved the strong red upconversion emission of...     

Synthesis and enhanced gas sensing properties of flower-like ZnO/α-Fe2O3 core-shell nanorods

This paper reports a facile two-step synthesis route for the preparation of flower-like ZnO/α-Fe₂O₃ nanorods (NRs). Flower-like ZnO NRs with the average diameter about 810 nm and length about 4.5 µm were firstly synthesized via a chemical solution method, and then ZnO NRs was coated with a continuous α-Fe₂O₃ layer to form ZnO/α-Fe₂O₃ core-shell structure through an ionic-layer adsorption and reaction method. The gas-sensing results show that the ZnO/α-Fe₂O₃ NRs exhibit excellent sensitivity, selectivity, and response-recovery capacity to ethanol vapor at a low optimum temperature of 240 °C. In particular, compared with pure ZnO NRs and α-Fe₂O₃ nanoparticles (NPs), the ZnO/α-Fe₂O₃ NRs show an obvious improvement in gas sensing properties. The substantial improvement of sensing properties may be attributed to the unique microstructure and heterojunction formed between ZnO and α-Fe₂O₃.     

Two-dimensional-growth small molecular hole-transporting layer by ultrasonic spray coating for organic light-emitting devices

Two-dimensional-growth small molecular organic thin film with high quality is fabricated by ultrasonic spray coating technology (USC) from the toluene solution of 4,4′,4″-tris (carbazol-9-yl) triphenylamine (TCTA). In comparison to the vacuum thermal evaporation (VTE) TCTA film, the USC-TCTA film obtained from liquid-phase solution possesses more uniform surface topography. The differences between the USC-TCTA and the VTE-TCTA in optical property, electrical property and formation mechanism are also studied in detail. Besides, to evaluate the hole transport and electron blocking ability of USC-TCTA film, the organic light-emitting devices (OLEDs) employing USC-TCTA film as hole transport layer are fabricated successfully. Additionally, the green OLEDs based on USC-TCTA film perform as well as the ones with VTE-TCTA film in current density, luminance, efficiency and color stability, and show even better tolerance to high bias voltage.