液相色谱/四极杆-飞行时间质谱法筛查奶酪中29种禁用和限用合成色素

建立了奶酪样品中29种禁用和限用合成色素的液相色谱/四极杆-飞行时间质谱(LC/Q-TOF MS)筛查方法。样品经正己烷-水(3:1, v/v)振荡提取,得到正己烷层、水层和残渣3部分。正己烷层经旋转蒸发浓缩后,用乙酸乙酯-环己烷(1:1, v/v)溶解,经过凝胶渗透色谱(GPC)净化去除油脂。水层经乙腈振荡提取,得到乙腈-水提取液。残渣经氨水-甲醇(1:99, v/v)溶液振荡提取,得到氨水-甲醇提取液。乙腈-水提取液和氨水-甲醇提取液不需净化直接分析。结果表明: 29种不同极性范围的合成色素化合物分别得到了有效的提取,提取回收率为70%～95%。而Q-TOF MS提供的精确质量数定性功能可以将不同种类的合成色素化合物筛查出来,各化合物与精确质量质谱库中化合物的匹配度为59.66～99.47。通过Target MS/MS扫描方式进行定量,得到8种苏丹类化合物的方法检出限为0.4～2.5 μg/kg, 21种水溶性合成色素及染料化合物的检出限为20～80 μg/kg。该方法对禁用和限用合成色素的筛查范围广泛,对含有蛋白质、脂肪等基质的食品具有较好的适用性。     

物理专业普通化学课程教学改革初探

结合物理专业特点,从确立课程主线入手进行普通化学教学内容和教学方式改革,使教师授课和学生学习的重点更为突出,内容更加新颖丰富。     

耐辐照玻璃成分分析标准物质的研制

采用高温熔融方法制备了玻璃成分分析标准物质.对标准物质的制备技术、均匀性检验、稳定性考察及定值不确定度进行了分析.研制的耐辐照成分分析标准物质具有良好的均匀性和稳定性,各组分不确定度均小于5％.     

DNA-templated ensemble for label-free and real-time fluorescence turn-on detection of enzymatic/oxidative cleavage of single-stranded DNA

We have demonstrated a DNA-templated small molecule ensemble that allows the label-free fluorescence turn-on detection of enzymatic or oxidative cleavage of single-stranded DNA with high sensitivity and selectivity.     

A label-free fluorescent turn-on enzymatic amplification assay for DNA detection using ligand-responsive G-quadruplex formation

A facile and general label-free assay for sensitive and selective DNA detection has been developed based on enzyme amplification and ligand-responsive quadruplex formation.     

Numerical scheme for solving system of fractional partial differential equations with Volterra‐type integral term through two‐dimensional block‐pulse functions

In the current study, an approximate scheme is established for solving the fractional partial differential equations (FPDEs) with Volterra integral terms via two‐dimensional block‐pulse functions (2D‐BPFs). According to the definitions and properties of 2D‐BPFs, the original problem is transformed into a system of linear algebra equations. By dispersing the unknown variables for these algebraic equations, the numerical solutions can be obtained. Besides, the proof of the convergence of this system is given. Finally, several numerical experiments are presented to test the feasibility and effectiveness of the proposed method.     

Propagation of a Hermite–Laguerre–Gaussian beam in a turbulent atmosphere

The propagation and spreading of a Hermite–Laguerre–Gaussian (HLG) beam in a turbulent atmosphere has been investigated. Based on the extended Huygens–Fresnel integral and some mathematical techniques, analytical expressions for the average intensity, the effective beam size, and the kurtosis parameter of an HLG beam in a turbulent atmosphere are derived, respectively. The average intensity distribution and the spreading properties of HLG beams in a turbulent atmosphere are numerically demonstrated. Upon propagation in a turbulent atmosphere, the central lobes in the beam spot of the HLG beam will evolve into the dominant lobes, and the peripheral lobes around the central lobes will evolve into the subdominant lobes. The influences of the additional angle parameter and the transversal mode numbers on the propagation of HLG beams in a turbulent atmosphere are also discussed. As the coherence length of the turbulence is determined by the propagation distance, the effect of the additional angle parameter on the effective beam size is related to the propagation distance. The kurtosis parameter generally increases with increasing the additional angle parameter. The influence of the transversal mode numbers on the kurtosis parameter is related to the additional angle parameter and the propagation distance. According to the practical need of free-space optical communications and remote sensing, the HLG beam in a turbulent atmosphere can be controlled by choice of the additional angle parameter and the transversal mode numbers.     

2×40 Gb/s OCDM using superstructure fiber Bragg gratings en/decoder

A 7-chip, 280 Gb/s optical code-division multiplexing (OCDM) system incorporating quaternary phase coding and decoding superstructured fiber Bragg gratings (SSFBGs) is experimentally demonstrated. Only ordinary phase masks and sub-micrometer precision are needed to fabricate the encoding and decoding SSFBGs. Interchannel interference noise is also considered and evaluated, 2-channel 40 (Gb/s)/channel(2×40 Gb/s) signal transmission is demonstrated.     

Preconcentration of rare earth elements on silica gel loaded with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one prior to their determination by ICP-AES.

A new chelating resin, silica gel loaded with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (PMBP), was prepared and used for the preconcentration of trace amounts of rare earth elements (REEs) in water samples prior to their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). REEs (La, Eu, Yb and Y) were quantitatively retained on the column packed with modified silica gel in the pH range 5 - 8 and separated from the matrix, and then recovered by eluting with 2.0 mol L(-1) HNO3. The adsorption capacity of modified silica gel for La, Eu, Yb and Y was 0.208, 0.249, 0.239 and 0.224 mmol g(-1), respectively. The method has been successfully applied for the determination of La, Eu, Yb and Y in geological and environmental samples with satisfactory results.