邻二氮菲双波长分光光度法测定牙膏中微量铁

用邻二氮菲作显色剂光度法测定铁(Ⅱ)早有报导。但由于牙膏成分复杂,试样直接用酸分解所得溶液往往带有浑浊,给光度测定造成困难。对此,一般采用两种方法处理:(1)高温灼烧试样,所得灰份溶解于酸中,然后显色、测量;(2)直接用酸分解试样,所得浑浊液用标准加入法抵消基体的影响,手续繁杂、费时。我们采用邻二氮菲简易双波长分光光度测定铁,得到了满意结果。     

一种基于碳酸锶纳米材料的催化发光乙醛气体传感器研究

研制了一种使用碳酸锶纳米材料作为敏感材料,用来检测空气中痕量乙醛气体的催化发光传感器。该传感器在342℃对乙醛有高灵敏度和选择性,在波长425nm处进行定量分析,催化发光强度与乙醛浓度的线性范围为6～6000mL／m^3(r=0．9995,n=8);检出限为2mL／m^3(信噪比=3)。外来物质如环己烷、四氯化碳、氨、苯、氯仿、甲苯、甲醇、乙醇及甲醛气体通过传感器时,除了乙醇和甲醛分别引起42．5％和12．5％的干扰外,其它气体不干扰测定。20000mL／m^3的水蒸气不干扰200mL／m^3乙醛气体的测定。连续1130h通过乙醛气体测试了传感器的稳定性。对含有乙醛、甲醛和苯的人工合成样品进行了分析。     

Probing the improved stability for high nickel cathode via dual-element modification in lithium-ion

One of the major hurdles of nickel-rich cathode materials for lithium-ion batteries is the low cycling stability, especially at high temperature and high voltage, originating from severe structural degradation, which makes this class of cathode less practical. Herein, we compared the effect of single and dual ions on electrochemical performance of high nickel (LiNi_0.88Mn_0.03Co_0.09O₂, NMC) cathode material in different temperatures and voltage ranges. The addition of a few amounts of tantalum (0.2 wt%) and boron (0.05 wt%) lead to improved electrochemical performance. The co-modified LiNi_0.88Mn_0.03Co_0.09O₂ displays an initial discharge capacity of 234.9 mAh/g at 0.1 C and retained 208 mAh/g at 1 C after 100 cycles at 45 ℃, which corresponds to a capacity retention of 88.5%, compared to the initial discharge capacity of 234.1 mAh/g and retained capacity of 200.5 mAh/g (85.6%). The enhanced capacity retention is attributed to the synergetic effect of foreign elements by acting as a surface structural stabilizer without sacrificing specific capacity.     

Finite-Width Correction to Form Factors of γγ^＊→ π^0 Transition

Instead of the usual zero-width approximation for one resonance, we use the finite-width approximation for the two low resonances, i.e. the ρ- ω mesons, to investigate the light-cone local QCD sum rules for the form factor of the transition γγ^＊→ π^0 ,According to the method of the analytic continuation by duality, the weight function, the polynomial of a low order N, is added to the dispersion integral to annihilate the integrand in the region where both resonance saturation and the QCD asymptotic expression are least reliable. The resultant form factor in the cases for the zero- and finite-widths are almost the same, both agree well with the experimental measurements. A comparison with the result from the Laplacian transformed light-cone sum rules and a brief discussion are given.     

蓝色圆珠笔油墨紫外光照射变化的研究

在紫外光照射下，通过对蓝色圆珠笔字迹色痕ＦＴ－ＩＲ显微光谱的研究。发现溶剂挥发迅速。其次是环氧树脂的聚合、交联；三苯甲烷染料的分解比较缓慢；而醇酸树脂相对稳定。该研究为字迹色痕的进一步分辨提供了新方法，同时为字迹色痕的“年龄”推断奠定了基础。选用相关峰的相对峰高比来描述这一变化，并进行曲线拟合，消除了因笔力不同而引起的油墨流出量不同造成的误差，这在实际工作中是很有意义的。     

基于DNA的比色分析法快速测定尿液中的Hg2+

以琼脂糖珠作为固定DNA的载体,建立了可视化的快速检测尿液中Hg2+的方法。DNA对Hg2+特异性识别后,其构象发生变化,启动相邻序列DNA酶的类过氧化物酶催化活性,进而催化氧化双氧水介导的ABTS(2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸))体系,溶液显绿色。考察了各种物质用量对检测体系的影响。在最优实验条件下,体系在420 nm处的吸光度与Hg2+浓度呈良好线性关系,线性范围为5~200 nmol/L,检出限为2 nmol/L。应用于真实尿样中Hg2+检测,加标回收率为95.1%~99.8%,相对标准偏差(n=5)为1.5%~3.1%。本方法对Hg2+具有良好的选择性,且检测不受其它金属离子干扰。另外,以琼脂糖珠为固相载体,能实现高效快速分离,有效排除尿液中其它物质对显色的影响,提高了检测的准确度和灵敏度。     

Proximity effects in topological insulator heterostructures

Topological insulators （Tls） are bulk insulators that possess robust helical conducting states along their interfaces with conventional insulators. A tremendous research effort has recently been devoted to TI-based heterostructures, in which con- ventional proximity effects give rise to a series of exotic physical phenomena. This paper reviews our recent studies on the potential existence of topological proximity effects at the interface between a topological insulator and a normal insu- lator or other topologically trivial systems. Using first-principles approaches, we have realized the tunability of the vertical location of the topological helical state via intriguing dual-proximity effects. To further elucidate the control parameters of this effect, we have used the graphene-based heterostructures as prototypical systems to reveal a more complete phase diagram. On the application side of the topological helical states, we have presented a catalysis example, where the topo- logical helical state plays an essential role in facilitating surface reactions by serving as an effective electron bath, These discoveries lay the foundation for accurate manipulation of the real space properties of the topological helical state in TI- based heterostructures and pave the way for realization of the salient functionality of topological insulators in future device applications.     

PBX-9404炸药高压反应速率方程的研究

研究了ＰＢＸ ９４０４ 炸药在高幅值冲击波加载下的化学反应速率方程。将所得高压反应速率方程与Ｊｏｈｎｓｏｎ 等的经验热点模型的低压项结合,得到ＰＢＸ ９４０４ 炸药的冲击波起爆反应速率模型。利用一维特征线程序模拟该炸药的冲击波起爆过程和爆轰波传播过程。     

伊红探针可视化检测牛奶中环丙沙星残留

基于伊红和环丙沙星离子缔合形成二元复合物后,溶液颜色由琥珀色转变成玫红色,构建了以伊红为探针的环丙沙星定量可视化检测体系。对缔合物的组成比进行了确认,对溶液pH、伊红用量进行了优化。在最优实验条件下,体系在540 nm,环丙沙星浓度在5～17μmol/L范围内与吸光度呈良好线性关系,检出限为3.57μmol/L,裸眼观察的检出限为2μmol/L。方法应用于实际样品牛奶中环丙沙星检测时,回收率在91.5%～97.0%之间,相对标准偏差(RSD)小于5.4%。方法适用于动物源性食品中环丙沙星的快速筛查。