反相高效液相色谱法同时测定果汁中8种添加剂

建立了反相高效液相色谱法（ＲＰ－ＨＰＬＣ）同时直接测定进口果汁中柠檬黄和苋菜红等８种添加剂含量的方法。色谱柱为Ｈｙｐｅｒｓｉｌ　ＢＤＳ　Ｃ１８柱（２５０ｍｍ×４．０ｍｍｉ．ｄ,５μｍ）,流动相为甲醇／０．０１ｍｏｌ／Ｌ乙酸铵,梯度洗脱,流速为 １．０ ｍＬ／ｍｉｎ,柱温为 ４０℃,ＤＡＤ紫外检测器波长为 ２３０ ｎｍ。在此色谱条件下,各组分在１０ ｍｉｎ内均得到良好分离。平均回收率为 ９０％～１１４％,相对标准偏差 １．３％～８．０％。     

Suitability of Different 13C Solid-state NMR Techniques in the Characterization of Humic Acids

Qualitative and quantitative analyses of humic acids (HAs) with five different ¹³C solid-state NMR techniques were assessed using HAs of various origins and locations. The NMR techniques compared are: (1) direct polarization/magic angle spinning (DP/MAS) at 13 kHz, (2) conventional cross polarization (CP)/MAS at 5 kHz, (3) ramp-CP/MAS at 8 kHz, (4) CP/total sideband suppression (TOSS) at 4.5 kHz, and (5) DP/MAS corrected by CP/spin-lattice relaxation with TOSS. The spectra from the five techniques were first compared qualitatively. Then, each spectrum was divided into eight regions for quantitative evaluation. DP/MAS spectra were used as quantitative references. Ramp-CP/MAS and CP/TOSS spectra gave consistently better results than those of the conventional CP/MAS spectra at a ¹³C frequency of 75 MHz, which were incorrect due to spinning sidebands. CP/MAS at low magnetic fields (22.6 and 50.6 MHz ¹³C frequency) indicated improved integration results but lower resolution. Correction factors calculated by comparison with DP/MAS will be useful to convert the non-quantitative peak areas in the CP/TOSS and ramp-CP/MAS spectra into more quantitative results.     

Effective in-device r33 of 735 pm/V on electro-optic polymer infiltrated silicon photonic crystal slot waveguides

We design and fabricate a 320?nm slot for an electro-optic (E-O) polymer infiltrated silicon photonic crystal waveguide. Because of the large slot width, the poling efficiency of the infiltrated E-O polymer (AJCKL1/amorphous polycarbonate) is significantly improved. When coupled with the slow light effect from the silicon photonic crystal waveguide, an effective in-device r(33) of 735?pm/V, which to our knowledge is a record high, is demonstrated, which is ten times higher than the E-O coefficient achieved in thin film material. Because of this ultrahigh E-O efficiency, the V(π)L of the device is only 0.44?V?mm, which is to our knowledge the best result of all E-O polymer modulators.     

An n-channel two-dimensional covalent organic framework

Co-condensation of metallophthalocyanine with an electron-deficient benzothiadiazole (BTDA) block leads to the formation of a two-dimensional covalent organic framework (2D-NiPc-BTDA COF) that assumes a belt shape and consists of AA stacking of 2D polymer sheets. Integration of BTDA blocks at the edges of a tetragonal metallophthalocyanine COF causes drastic changes in the carrier-transport mode and a switch from a hole-transporting skeleton to an electron-transporting framework. 2D-NiPc-BTDA COF exhibits broad and enhanced absorbance up to 1000 nm, shows panchromatic photoconductivity, is highly sensitive to near-infrared photons, and has excellent electron mobility as high as 0.6 cm(2) V(-1) s(-1).     

Accurate Monte Carlo tests of the stochastic Ginzburg-Landau model with multiplicative colored noise

A accurate and fast Monte Carlo algorithm is proposed for solving the Ginzburg-Landau equation with multiplicative colored noise. The stable cases of solution for choosing time steps and trajectory numbers are discussed.     

不同幅值过电流下的高温超导线材失超发展过程

对高温超导材料的失超特性的研究是超导电力科学技术中的重要课题 ,为此 ,本实验室进行了大量的实验工作。在此基础上 ,文中整理了部分高温超导实验数据 ,对其进行分析和归纳总结 ,提出了高温超导线材失超三阶段理论     

Evaluation of a rapid method for the quantitative analysis of fatty acids in various matrices

A simplified method for quantitative analysis of fatty acids in various matrices by gas chromatography is proposed as an alternative to the conventional method and the variables of the protocol examined to optimize the processing conditions. The modified method involves direct methylation of fatty acids in homogenized samples with boron trihalide (BF(3) or BCl(3) in methanol) followed by extraction with hexane. The addition of hexane to the reaction mixture after the methylation process can enhance the efficiency of fatty acid methylation and is critical for those samples that contain high levels of triglycerides. A mechanism underlying this effect is proposed.     

Phenyltetraene-based nonlinear optical chromophores with enhanced chemical stability and electrooptic activity

"Push-pull" phenyltetraene-based chromophores are too sensitive to be incorporated into Diels-Alder-type cross-linkable polymers due to the reactivity of its diene segment with maleimides. A facile synthetic route has been explored to incorporate a methoxy group into the R position of such chromophores, which reduces their diene reactivity during the poling and lattice hardening process. The poled polymers with one of such chromophores doped in a cross-linked polymer lattice showed ultrahigh electro-optic activities, up to 306 pm/V at 1310 nm.     

高温超导变压器在电网中的应用

随着高温超导带材性能的不断提高,高温超导变压器在电力系统中的应用可以有效提高系统效率。在广泛调研的基础上,分析了高温超导变压器的关键技术以及目前的技术瓶颈。在此基础上,结合近几年来国内外对高温超导变压器的研究进展,对高温超导变压器的应用前景进行了分析,并给出了高温超导变压器的发展路线。