气相色谱正构烷烃和直链脂肪酸甲酯两种线性保留指数之间的转换方法

保留指数是气相色谱中用于化合物结构鉴定的重要工具。本研究对基于正构烷烃和直链脂肪酸甲酯的线性保留指数进行线性拟合,发现在所设定的4种不同的升温条件下两种保留指数之间呈现较为固定的线性关系：在弱极性柱（固定液为5%苯基和95%的甲基聚硅氧烷）和极性柱（固定液为聚乙二醇）条件下,正构烷烃保留指数（y）与脂肪酸甲酯保留指数（x）之间的关系分别为y=1.0051x+318.51（r²=1）和y=1.0362x+562.519（r²=1）。采用文献保留指数对所建立的线性关系进行验证,发现通过公式换算得到的保留指数均在其对应文献值的均值加减方差范围内,说明换算公式真实有效。两种保留指数之间关系的建立对于化合物结构鉴定时扩大保留指数搜索范围、减少保留指数测定实验具有重要意义。     

In situ Carbon Modification of g-C3N4 from Urea co-Crystal with Enhanced Photocatalytic Activity Towards Degradation of Organic Dyes Under Visible Light

An in situ strategy was introduced for synthesizing carbon modified graphitic carbon nitride(g-C₃N₄) by using urea/4-aminobenzoic acid(PABA) co-crystal(PABA@Urea) as precursor materials. Via co-calcination of the PABA co-former and the urea in PABA@Urea co-crystals, C guest species were generated and compounded into g-C₃N₄ matrix in situ by replacing the lattice N of the carbon nitride and forming carbon dots onto its layer surface. The carbon modification dramatically enhanced visible-light harvesting and charge carrier separation. Therefore, visible light photo-catalytic oxidation of methylene blue(MB) pollution in water over the carbon modified g-C₃N₄(C/g-C₃N₄) was notably improved. Up to 99% of methylene blue(MB) was eliminated within 60 min by the optimal sample prepared from the PABA@Urea co-crystal with a PABA content of 0.1%(mass ratio), faster than the degradation rate over bare g-C₃N₄. The present study demonstrates a new way to boost up the photocatalysis performance of g-C₃N₄, which holds great potential concerning the degradation of organic dyes from water.     

Meta-DNA Strategy to Assemble DNA Structures in Submicrometre and Micrometre Scale

To break through the size limitation in DNA structure assembly and to achieve the construction of DNA structures with submicrometre and micrometre scale, Fan and Yan et al. proposed a versatile DNA structure assembly strategy, named as meta-DNA(M-DNA) strategy. Submicrometre-sized M-DNA, which has a six-helix bundle DNA origami nanostructure, is used as building block to precisely assemble a series of submicrometre-to-micrometre-sized DNA architectures with customed shapes, including meta-multi-arm junctions, polyhedrons and closely packed lattices. Besides static assembly, the proposed M-DNA strategy was also demonstrated to work well for the programmed dynamic rearrangement of DNA structures. This work has been published online in the Nature Chemistry on September 7, 2020.     

银杏叶化学组分群动态FTIR指纹图谱研究

比较了相同产地不同月份与相同月份不同产地银杏叶的FTIR图谱,研究了银杏叶化学组分群随气候、季节、地域等的差异而呈现出的动态分布规律。结果表明,从4月份到10月份,银杏叶内化学组分群呈现动态分布与变化,其变化在6月16日,9月1日,10月4日3个时段。5月份所采集的不同产地银杏叶的化学组分群分布基本一致。这在银杏叶药材种植质量管理规范(GAP)基地的建设、确保银杏叶原料的稳定性以及其后各类相关指纹图谱的研究及制定等方面具有重要意义。     

Coumarin-glycoside and Ferulate from Peucedanum decursivum

The root of Peucedanum decursivum (Miq.) Maxim (umbelliferae) is known as a famoustraditional Chinese medicine. In our Studies on the chemical constituents, compounds Iand 2 were isolated from the extract of the roots by combination of silica gel columnchromatography and preparative HPLC.Compound l, yellow powder, C,.H,,O., (HRFAB-MS (M-H) - m/z. cafed. 475. 1604.ohs. 475.1594), UV spectrum (X max 334 and 203 "m), IH and 13C NMR spectra werequite similar to those of furocoumarin gl…     

单一多体不可逆聚集方程的解

本文研究的是单一多体不可逆聚集方程的解,从广义Smoluchovski方程出发,分别讨论凝结核为K(i₁,i₂,…,i_n)=const和凝结核为K(i₁,i₂,…,i_n)=sumfrom i=1 to n(i_l)的精确解,求出集团的体积分布C_m(t)。并且还讨论它们的长时行为。 关键词：     

用反差确定电子束曝光剂量与刻蚀深度的关系

 为了精确地确定电子束曝光剂量与刻蚀深度间的关系，根据抗蚀剂的灵敏度曲线，采用反差经验公式来确定剂量与刻蚀深度间的关系。选用正性抗蚀剂PMMA进行曝光实验，将计算值进行曲线拟合，得到的关系曲线与实验结果基本相符。当剂量在20~35 μC/cm²间时，实验值与计算值间的差值最小，说明当剂量在此范围内时该方法能够更加精确地确定剂量与刻蚀深度间的关系。采用该方法节省了实验时间，提高了刻蚀效率。     

超视力人眼模型的研究

超视力人眼模型对充分发掘人眼视力达到“鹰视”具有重要意义。用Zernike多项式描述角膜前表面，用渐变折射率描述晶状体的折射率分布，同时考虑人眼视轴和光轴的夹角对成像的影响，利用光学设计软件Zemax建立了人眼超视力模型。将Zernike条纹矢高面应用到人眼模型中，能有效改变视轴方向(即5°视场)的成像质量，提高点扩散函数（PSF）值。采用晶状体渐变折射率符合人眼的实际解剖结构，可有效减小人眼像差。通过分析人眼极限分辨能力和人眼模型波像差，得出当空间频率为60周期/度时，该模型对目标高频细节感知的调制度可达到0.55。     

Pr^3＋或Sm^3＋掺杂YAG∶Ce的发光特性及其荧光寿命

研究了Pr3 ,Sm3 掺杂对YAG∶Ce发射光谱及其荧光寿命的影响。观察到当掺杂Pr3 时,在609nm处出现Pr3 的发射峰,而掺杂Sm3 时,在616nm处呈现Sm3 的发射峰。掺杂Pr3 或Sm3 增加红光区的发射峰将有利于提高YAG∶Ce荧光粉的显色性。实验中测定了(Y0.95Sm0.01Ce0.04)3Al5O12、(Y0.95Pr0.01Ce0.04)3Al5O12、(Y0.96Ce0.04)3Al5O12的荧光寿命(τ),观察到在YAG∶Ce中掺入Pr3 或Sm3 使Ce3 的荧光寿命减小。实验结果表明,少量掺杂Pr3 或Sm3 并未引起基质的结构的变化。