亲水作用色谱-串联质谱法测定动物源运动食品中3种氨基糖苷类抗生素的残留量

该研究建立了一种亲水交互作用色谱-串联质谱（HILIC-MS/MS）法测定动物源运动食品中潮霉素B、新霉素、安普霉素3种氨基糖苷类抗生素残留量的方法。结果表明，样品经Sielc Obelisc R柱分离，采用0.1%甲酸水溶液-乙腈梯度洗脱，可以实现3种目标物组分的分离。在此条件下，3种氨基糖苷类抗生素在5～500 ng/mL的质量浓度范围内线性关系良好，相关系数R2为0.999 5～0.999 9，检出限均为15 μg/kg，定量限均为50 μg/kg，保留时间的日间和日内相对标准偏差（RSD）分别为3.5%～7.9%和3.5%～4.1%，峰面积的日间和日内RSD分别为3.6%～7.4%和3.2%～3.9%，加标回收率为85.7%～93.6%，回收率试验结果的RSD为3.1%～5.2%。该方法可以满足动物源运动食品中3种氨基糖苷类抗生素的检测需求。     

Rapid screening of DON contamination in whole wheat meals by Vis/NIR spectroscopy and computer vision coupling technology

This work intends to develop an online experimental system for screening of deoxynivalenol (DON) contamination in whole wheat meals by visible/near-infrared (Vis/NIR) spectroscopy and computer vision coupling technology. Spectral and image information of samples with various DON levels was collected at speed of 0.15 m s⁻¹ on a conveyor belt. The two-type data were then integrated and subjected to chemometric analysis. Discriminant analysis showed that samples could be classified by setting 1000 μg kg⁻¹ as the cut-off value. The best correct classified rate obtained in prediction was 93.55% based on fusion of spectral and image features, with reduced prediction uncertainty as compared to single feature. However, quantification of DON by quantitative analysis was not successful due to poor model performance. These results indicate that, although not accurate enough to provide conclusive result, this coupling technology could be adopted for rapid screening of DON contamination in cereals and feeds during processing.     

Combustion synthesis of AlN doped with carbon and oxygen

Carbon-and-oxygen-doped AlN specimens were prepared by combustion synthesis using Al, graphite, and AlN. Graphite addition changed the product color from white to blue. By XRD, the lattice constant increased slightly with increasing carbon content. Blue AlN powder was synthesized with a molar ratio of the diluent AlN of 0.2-0.5 with a fixed graphite content of 0.05. At an AlN molar ratio exceeding 0.6, carbon was not successfully incorporated due to the lower reaction temperature. Calcination at 800°C in air removed residual graphite without changing the crystal structure or product color. Oxygen, nitrogen, and carbon analyses revealed that blue AlN powders contained 0.45-0.54 mass% carbon and 1.4-1.6 mass% oxygen, while the undoped AlN contained 0.021 mass% carbon and 0.94 mass% oxygen. The origin of the white-to-blue color change was investigated via reflection measurements. Blue AlN exhibits an absorption peak at 634 nm (1.96 eV). From first-principles electronic structure calculations, the C-doped AlN and carbon-and-oxygen-doped AlN with a 1:1 ratio could be classified as p-type, whereas the O-doped AlN and 1:3 carbon-and-oxygen-doped AlN were n-type. One reason for the absorption peak at 634 nm may be a transition from the conduction band to an upper unoccupied state. These results suggest the possible control of optical and electronic properties of AlN via carbon-and-oxygen doping.     

DC conductivity and AC impedance of Mn doped magnesia alumina spinel (MgAl2-2xMn2xO4) over a large temperature range

MgAl_2-2xMn_2xO₄ (MAMO) with x = 0-0.12 was synthesized in a single-phase form by solid-state reaction. XRD analysis showed that the samples had the cubic center structure of the Fd-3 m space group. Electrical properties of the samples were studied over the temperature range of 300 K∼1073 K. The results showed that the DC conductivity (σ_DC) increased from 10⁻¹¹S/cm at 300 K (MAMO, x = 0) to 10^-3S/cm at 1073 K (MAMO, x = 0.12). The equivalent circuit of the complex impedance spectra suggested that the relaxation of charge carriers was of non-Debye type. The conduction was mainly caused by grain boundaries and the capacitance was mainly attributed to polarization. The complex permittivity values (ε’ and ε’’) were increased by two orders of magnitude with the increase in Mn content and temperature over the measured frequency range (1 Hz-1 MHz). Therefore, doping with Mn could be applied to modify the electrical properties of MAMO at high temperature.     

Techno-economic analysis of hydrogen energy for renewable energy power smoothing

With the increasing proportion of renewable energy (mainly wind power and photovoltaic) connected to the grid, the fluctuation of renewable energy power brings great challenges to the safe and reliable operation of power grid. As a clean, low-carbon secondary energy, hydrogen energy is applied in renewable energy (mainly wind power and photovoltaic) grid-connected power smoothing, which opens up a new way of coupling hydrogen storage energy with renewable energy. This paper focuses on the optimization of capacity of electrolyzers and fuel cells and the analysis of system economy in the process of power output smoothing of wind/photovoltaic coupled hydrogen energy grid-connected system. Based on the complementary characteristics of particle swarm optimization (PSO) and chemical reaction optimization algorithm (CROA), a particle swarm optimization-chemical reaction optimization algorithm (PSO-CROA) are proposed. Aiming at maximizing system profit, the capacity of electrolyzers and fuel cells are constrained by wind power fluctuation, and considering environmental benefits, government subsidies and time value of funds, the objective function and its constraints are established. According to the simulation analysis, by comparing the calculated results with PSO and CROA, it shows that PSO-CROA effectively evaluates the economy of the system, and optimizes the optimal capacity of the electrolyzers and fuel cells. The conclusion of this paper is of great significance for the application of hydrogen energy storage in the evaluation of power smoothness and economy of renewable energy grid connection and the calculation of economic allocation of hydrogen energy storage capacity.     

碘化多壁碳纳米管制备含有Ag/MWCNTs复合材料的银-环氧树脂浆料

提出一种将多壁碳纳米管碘化后制备银/多壁碳纳米管（Ag/MWCNTs）复合材料的方法。通过球磨对碘化多壁碳纳米管进行了功能化，并通过透射电子显微镜（TEM）、X射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、拉曼光谱和热重分析（TG）对其进行了表征。结果表明，经碘化处理后，银纳米粒子（Ag-NPs）能更好地粘附在碳纳米管表面，改善了银纳米粒子与碳纳米管之间的连接。羟基（-OH）基团的伸缩振动明显增强，激活了碳纳米管的表面，增加了碳纳米管表面Ag⁺形核的数量。在260 ℃以下，Ag/MWCNTs复合材料的质量损失小于MWCNTs的质量损失。最后，制备了银-环氧树脂浆料，发现使用Ag/MWCNTs复合物制备的浆料具有最低的电阻率和最高的热导率。     

Surface structure and quenching effects in BiFeO3-BaTiO3 ceramics

The structure and properties of Mn-doped 0.67BiFeO₃-0.33BaTiO₃ ceramics are systematically investigated with respect to the effects of annealing prior to rapid cooling by quenching in air. Air-quenching induces a change in crystal structure from pseudo-cubic to rhombohedral, with higher quenching temperatures leading to an increased rhombohedral distortion. These structural changes are correlated with the appearance of more well-defined ferroelectric domain configurations. It is shown that the surface preparation procedures for XRD measurements can induce significant changes in the peak profiles, indicating differences in crystal structure between the surface and bulk regions. Frequency dispersion in the temperature-dependent relative permittivity for the as-sintered sample is significantly reduced after quenching, accompanied by enhancement of the Curie point and improved temperature-stability of piezoelectric properties. It is proposed that the formation of defect clusters by A-site cation diffusion during cooling is circumvented by quenching, leading to the observed modification of structural distortion and ferroelectric properties.     

Aluminum to germanium inversion in mullite-type RAlGeO5: Characterization of a rare phenomenon for R = Y,Sm–Lu

Mullite-type RMn₂O₅ (R = Y, rare-earth element) ceramics are of ongoing research attentions because of their interesting crystal-chemical, physical, and thermal properties. We report a detailed structural, spectroscopic and thermal analysis of the series of mullite-type RAlGeO₅ (R = Y, Sm-Lu) phases. Polycrystalline samples are prepared by solid-state synthesis methods. Each sample is characterized by X-ray powder diffraction followed by Rietveld refinements, showing that they are isotypic and crystallize in the space group Pbam. The change of the metric parameters is explained in term of the lanthanide contraction effect. A rare inversion of Al/Ge between octahedral and pyramidal sites have been observed for these mullite-type so called O10 compounds, and the inversion parameter found to be between 0.22(1) and 0.30(1) for different R-cations. The <Al/Ge–O> bond distances and their bond valence sums (BVSs) support the respective inversions. Density functional theory (DFT) calculated phonon density of states (PDOS) and electronic band structures are compared for the vibrational and electronic band gap features respectively. Analysis of UV/Vis absorption spectra using both derivation of absorption spectra fitting (DASF) and Tauc's methods demonstrates that each of the RAlGeO₅ O10 compounds is high bandgap semiconductor, possessing direct transition between 4.1(1) and 5.4(1) eV. Both Raman and Fourier transform infrared spectra show clear red shift (quasi-harmonic) of the vibrational wavenumbers with respect to the ionic radii of the R-cations. Selective Raman bands at higher wavenumber region further complement the inversion of Al/Ge between two coordination sites. The higher decomposition temperature of the RAlGeO₅ compounds, compared to those of RMn₂O₅ phases, is explained in terms of higher bond strength of Al/Ge-O than those of Mn-O. Irrespective to the inversion between Al- and Ge-sites, the decomposition temperature also depends on the type of R-cation in RAlGeO₅.     

Unique CNTs-chained Li4Ti5O12 nanoparticles as excellent high rate anode materials for Li-ion capacitors

Composite anode materials with a unique architecture of carbon nanotubes (CNTs)-chained spinel lithium titanate (Li₄Ti₅O₁₂, LTO) nanoparticles are prepared for lithium ion capacitors (LICs). The CNTs networks derived from commercial conductive slurry not only bring out a steric hindrance effect to restrict the growth of Li₄Ti₅O₁₂ particles but greatly enhance the electronic conductivity of the CNTs/LTO composites, both have contributed to the excellent rate capability and cycle stability. The capacity retention at 30 C (1 C = 175 mA g^?1) is as high as 89.7% of that at 0.2 C with a CNTs content of 11 wt%. Meanwhile, there is not any capacity degradation after 500 cycles at 5 C. The LIC assembled with activated carbon (AC) cathode and such a CNTs/LTO composite anode displays excellent energy storage properties, including a high energy density of 35 Wh kg^?1 at 7434 W kg^?1, and a high capacity retention of 87.8% after 2200 cycles at 1 A g^?1. These electrochemical performances outperform the reported data achieved on other LTO anode-based LICs. Considering the facile and scalable preparation process proposed herein, the CNTs/LTO composites can be very potential anode materials for hybrid capacitors towards high power-energy outputs.     

Joining zirconia with nickel-based superalloys for extreme applications by using a pressure-free high-temperature resistant adhesive

In order to meet the high demand for joining ceramic/superalloy composite structure in extreme environments, a novel high-temperature resistant adhesion technique was developed for joining ZrO₂ and Inconel 625 by applying an aluminum phosphate emulsion/zirconium sol based adhesive. With increasing temperature, a series of reactions occurred in adhesive, and its high-temperature bonding was attributed to the formation of a composite structure containing various ceramics and intermetallics. The adhesive after RT curing could find direct applications in extreme environments, and provide bonding strength no less than 2.5 MPa in the temperature range of RT-1100 °C. The bonding strength was higher than 4 MPa in the temperature range of 800–1000 °C, which was further attributed to the formation of an effective CTE-gradient relationship among ZrO₂, adhesive and Inconel 625, as well as the interfacial reactions between the two substrates. The work broadened the application of adhesion technique and brought new ideas for joining dissimilar engineering materials.