可见光条件下光敏剂引发的Aza-Henry反应

合成了3-甲氧基噻吨酮,并通过核磁共振、红外光谱、高分辨质谱对其结构进行表征。3-甲氧基噻吨酮紫外-可见光谱表明,其在可见光范围内的紫色光(380 nm)附近有吸收,是一种可见光光敏剂。将该光敏剂应用于2-苯基-1,2,3,4-四氢异喹啉和硝基甲烷的Aza-Henry反应中,在紫色LED光照射的条件下,摩尔分数为5%的光敏剂使反应在6 h内产物的分离产率为84%。根据实验结果,提出了光催化的Aza-Henry反应机理,光敏剂在光照条件下进行能量转移产生单线态氧,单线态氧促进Aza-Henry反应的进行。     

化学镀Ni-Fe-P工艺的研究

考察了镀液中FeSO4的质量浓度对合金镀层沉积速率的影响,并通过金相显微镜对镀层表面形貌进行观察;采用硬度计和实验室浸泡方法分别考察了镀层的显微硬度和耐蚀性.结果表明:当镀液中FeSO4的质量浓度小于2.0 g/L时,镀层的沉积速率虽然降低,但镀层的表面更加均匀、致密,表面质量更好,镀层的显微硬度和耐蚀性也得到提高;当...     

T-2毒素对不同生长期对虾的急性毒性及其分析方法的比较研究

比较T-2毒素对不同生长期凡纳滨对虾(Litopenaeus vannamei)的急性毒性及其分析方法,明确对虾作为T-2毒素毒性评价的生物标记物的最佳时期,建立T-2毒素对对虾的急性毒性互补评价方法。通过对不同生长期凡纳滨对虾的急性毒性试验,采用寇氏法和概率单位法,计算得到T-2毒素对不同生长期凡纳滨对虾的LD50,并通过u检验对两种方法求得的LD50值进行分析比较。结果得到T-2毒素对虾卵、幼虾和成虾的LD50值分别为2.33、1.79和3.34 mg/kg·bw,且经检验两种方法求得的LD50并无显著性差异。研究表明,T-2毒素对成虾的毒害作用最小急性毒性最弱,对幼虾的毒害作用最大急性毒性最强,即该生长期的凡纳滨对虾更适宜做评价T-2毒素急性毒性的生物标志物,同时采用寇氏法和概率单位法相结合的方法得到的LD50值更具准确。     

Effects of Sr2+ on structure and luminescent properties of BaAl12O19:Eu phosphors

Ba_0.9-ySr_yAl₁₂O₁₉:Eu_0.1 phosphors were prepared by sol-gel technique, the crystalline structures of samples characterized by XRD, and the luminescence properties were investigated. The influence of crystallographic positions on the luminescent properties of Sr²⁺-doped BaAl₁₂O₁₉:Eu was investigated in detail. The results indicated that the crystal lattice of BaAl₁₂O₁₉:Eu was not influenced by the Sr²⁺ and doping Sr²⁺ in BaAl₁₂O₁₉:Eu enhanced the luminescent properties of the phosphors at the proper concentration of Sr²⁺. With the increasing of concentration of Sr²⁺ doped in BaAl₁₂O₁₉:Eu, the relative luminescent intensity of Ba_0.9-ySr_yAl₁₂O₁₉:Eu_0.1 strengthened and blue-shifted.     

Luminescence properties of BaAl12O19:Tb,Ce and energy transfer between Ce3+, Tb3+

BaAl₁₂O₁₉:Tb,Ce phosphors were prepared by sol-gel technique, the crystalline structures of samples characterized by XRD, and the luminescence properties and energy transfer between Ce³⁺ and Tb³⁺ were investigated. The results indicated that the emission intensity and the excitation wavelength range of Tb³⁺ increased when Ce³⁺ was doped. It demonstrated that the Ce³⁺ added in the BaAl₁₂O₁₉:Tb could deliver energy to Tb³⁺, and Ce³⁺ was not luminous by itself. The relative emission intensity of Tb³⁺ at wavelength of 548 nm was the strongest by Tb³⁺/Ce³⁺ ratio of 2:1, when excited at 310 nm, which was the characteristic adsorption wavelength of Ce³⁺.     

Effects of Sr²⁺ on structure and luminescent properties of BaAl₁₂O₁₉:Eu phosphors

Ba0.9-ySryAl12O19:Eu0.1 phosphors were prepared by sol-gel technique,the crystalline structures of samples characterized by XRD,and the luminescence properties were investigated.The influence of crystallographic positions on the luminescent properties of Sr2+-doped BaAl12O19:Eu was investigated in detail.The results indicated that the crystal lattice of BaAl12O19:Eu was not influenced by the Sr2+ and doping Sr2+ in BaAl12O19:Eu enhanced the luminescent properties of the phosphors at the proper concentration of Sr2+.With the increasing of concentration of Sr2+ doped in BaAl12O19:Eu,the relative luminescent intensity of Ba0.9-ySryAl12O19:Eu0.1 strengthened and blue-shifted.     

高效液相色谱-质谱联用法测定豆芽中恩诺沙星含量

采用高效液相色谱-质谱联用法测定豆芽中恩诺沙星的含量。样品经0.1mol/L NaOH溶液提取后,经WatersOasis MAX阴离子交换柱净化,以双氟沙星为内标,采用反相高效液相色谱分离,以乙腈-水(含0.1%甲酸)为流动相进行梯度洗脱,通过带有电喷雾离子化源的串联质谱仪,应用正离子扫描,在多反应监测模式下进行定性与定量分析。本法线性范围为1～100μg/kg,平均回收率为91.6%～94.0%,相对标准偏差不大于6.6%,方法的检出限为0.3μg/kg。     

Luminescence properties of BaAl₁₂O₁₉:Tb,Ce and energy transfer between Ce³⁺,Tb³⁺

BaAl12O19:Tb,Ce phosphors were prepared by sol-gel technique,the crystalline structures of samples characterized by XRD,and the luminescence properties and energy transfer between Ce3+ and Tb3+ were investigated.The results indicated that the emission intensity and the excitation wavelength range of Tb3+ increased when Ce3+ was doped.It demonstrated that the Ce3+ added in the BaAl12O19:Tb could deliver energy to Tb3+,and Ce3+ was not luminous by itself.The relative emission intensity of Tb3+ at wavelength of 548 nm was the strongest by Tb3+/Ce3+ ratio of 2:1,when excited at 310 nm,which was the characteristic adsorption wavelength of Ce3+.     

我国食品质量与安全现状及对策

从宏观角度论述了目前我国食品质量与安全现状,并结合现状提出加强食品科学领域的基础研究,增强消费者、食品从业与监管人员的质量与安全意识以及建立多元化的监管体系将是进一步提高我国食品质量与安全水平的重要举措。     

Electrochemical performance and thermal property of electrospun PPESK/PVDF/PPESK composite separator for lithium-ion battery

In this study, PPESK/PVDF/PPESK tri-layer composite separators for lithium-ion batteries were prepared by electrospinning technique. The physical properties, electrochemical performances and thermal properties of composite separators were investigated. Results indicate that PPESK/PVDF/PPESK separator displays good wettability in liquid electrolyte. The electrolyte uptake of PPESK/PVDF/PPESK separator is much higher than that of electrospun PVDF, which leads to higher ionic conductivity of PPESK/PVDF/PPESK separator than PVDF separator. Discharge capacity of the cell assembled with PPESK/PVDF/PPESK separator is increased by 50 % than that with PVDF separator. Initial charge–discharge efficiency and capacity retention property of the cell with PPESK/PVDF/PPESK are better than those with PVDF separator or PPESK separator. In addition, when the mass ratio between PPESK and PVDF resins is increased to 4:3, PPESK/PVDF/PPESK separators show good thermal dimensional stability even thermally treated at 180 °C for 1 h.