柠檬果茶中游离态和键合态挥发性成分分析

以柠檬果茶为研究对象,建立了顶空固相微萃取前处理结合气相色谱质谱联用技术测定其中挥发性化合物的分析方法。采用开水冲泡对样品进行提取,通过Amberlite XAD-2大孔吸附树脂对柠檬果茶中的糖苷类挥发性组分键合,分离游离态和键合态化合物,甲醇溶剂作为洗脱剂对键合态化合物进行洗脱,Almondsβ-D-葡萄糖苷酶对其酶解。使用气质联用对样品中游离态和键合态挥发性成分进行检测,其结果根据数据库匹配和对比文献保留时间定性,内标法进行定量。结果表明,柠檬果茶中含有游离态物质24种,键合态物质16种,主要为(+)-柠檬烯、1-辛醇、橙花醇、(-)-4-萜品醇、alpha-松油醇等。方法为花果茶干燥工艺提供参考。     

甲烷-二氧化碳重整制合成气与现代分析技术应用于探究性化工专业实验的设计与探索

以甲烷-二氧化碳重整制合成气为实例，设计探究性实验，将合成气的制备和现代分析技术应用于化工专业实验的教学实践中以提高学生的创新和实践能力。实验包括催化剂的制备，催化剂的性能评价和催化剂的表征等3大部分。采用工业最常用的浸渍法制备含有不同助剂的Ni/X/γ-Al2O3（X为Co，Fe，MgO，CeO2）催化剂，以甲烷-二氧化碳重整反应评价其催化性能，并采用XRD、H2-TPR、BET和TG对催化剂的微观结构进行表征。结合催化剂的性能评价结果和表征结果，探讨不同助剂对镍基催化剂性能的改善效果及机制。通过开设该实验，可以让学生了解化工学科的前沿知识以及现代分析技术的基本原理和用途，掌握专业的实验操作、数据处理和谱图绘制方法，提高学生的专业素养和综合能力。     

磷酸化调控泛素单体与Rad23A/Ubiquilin-1中泛素结合域互作的检测

泛素（ubiquitin，Ub）是一种广泛存在、高度保守的信号蛋白质，它能够特异性识别成千上万种靶蛋白，以非共价方式行使不同的功能，其中包含蛋白质降解．Ubiquilin-1（Ubql-1）和Rad23A作为两种蛋白降解的转运因子，都包含有与泛素结合的结构域，被称为泛素结合域（ubiquitin-associated domain，UBA）．2014年，泛素S65位磷酸化修饰的特异性激酶PINK1被发现，磷酸化使泛素在溶液中呈现舒展态与收缩态两种互相转换的构象．本文通过核磁共振（nuclear magnetic resonance，NMR）技术对UBA和磷酸化泛素之间的相互作用进行检测，观测磷酸化对UBA和泛素结合的影响．实验结果表明Rad23A-UBA2与Ubql-1 UBA都特异性的与磷酸化泛素的舒展态相互作用，但是磷酸化未改变泛素与UBA之间的亲和力．值得注意的是与Ubql-1 UBA相互作用时，磷酸化促进了泛素收缩态向舒展态的转换．     

Research Progress and Application of Ion Funnel Technique

Ion funnel is a new-style ion guider which can reduce spatial divergence and energy dispersity of the transmission ions by using radio frequency (RF) electric field to confine the ions radially and the direct current (DC) axial electric field to move the ions toward the exit, and thus it can greatly increase the ion transmission efficiency and improve the sensitivity of the mass spectrometry. Since ion funnel was invented in 1997, it has attracted a close attention of mass spectrometry scientists all over the world. Ion funnel has been used in various kinds of mass spectrometry, and built a bridge with high efficiency ion transmission between low vacuum ionization source and high vacuum mass analyzer. In this paper, the principle, technology development, and application progress of ion funnel are reviewed, and the future prospects are prospected.     

熵的一种通俗教法

熵如力、能量和动量一样是物理学中一个重要概念,若能用一种通俗易懂的方法设计熵的教学,对文科物理的教学有重要意义.为此本文提出了一种通俗的熵的教法,这一教法不需要学生学习热力学第二定律也可以建立熵的概念.具体教学设计如下:通过日常生活例子引入熵的概念(也就是玻尔兹曼熵),设计两个例子让学生会计算熵,通过具体问题的讨论让学生充分理解熵的意义,通过一个实例由玻尔兹曼熵引入克劳修斯熵公式,设计一个演示实验强化教学效果,将熵与环境保护联系起来融入人文情怀,最后还强调了熵计算的不同层次.教学设计完全采用基于问题学习(PBL)的教学模式.     

Cephalotanins A–D,Four Norditerpenoids Represent Three Highly Rigid Carbon Skeletons from Cephalotaxus sinensis

Four polycyclic norditerpenoids, cephalotanins A–D ( 1 – 4 ) representing three unprecedented carbon skeletons with highly rigid ring systems, were isolated from Cephalotaxus sinensis and structurally characterized by a combination of various methods. Compounds 1 and 2 are new skeletal norditerpenoid trilactones, while 3 and 4 are two norditerpenoids featuring different new carbon skeletons. Biosynthetic pathways for 1 – 4 were proposed by involving diverse and very fascinating chemical events with the coexisting cephalotane troponoids as the precursors. Compound 1 exhibited good NF‐κB inhibition with an IC₅₀ value of 4.12±0.61 μΜ.     

配位化学课程中研究型教学模式探讨

In this paper, the implementation of research-oriented teaching mode in coordination chemistry was introduced, including the strategies, main contents and evaluation.     

The Effect of the Spacer of Bis(biurea) Ligands on the Structure of A2L3‐type (A=anion) Phosphate Complexes

By tuning the length and rigidity of the spacer of bis(biurea) ligands L, three structural motifs of the A₂L₃ complexes (A represents anion, here orthophosphate PO₄^3?), namely helicate, mesocate, and mono‐bridged motif, have been assembled by coordination of the ligand to phosphate anion. Crystal structure analysis indicated that in the three complexes, each of the phosphate ions is coordinated by twelve hydrogen bonds from six surrounding urea groups. The anion coordination properties in solution have also been studied. The results further demonstrate the coordination behavior of phosphate ion, which shows strong tendency for coordination saturation and geometrical preference, thus allowing for the assembly of novel anion coordination‐based structures as in transition‐metal complexes.     

不同变质程度煤的高分辨率透射电镜分析

利用高分辨率透射电子显微镜(HRTEM)分析了三种不同变质程度煤样的结构特征。基于傅里叶-反傅里叶变换方法,并结合Matlab、Arcgis和Auto CAD软件,通过图像分析技术,获得了HRTEM照片的晶格条纹参数。结果表明,三种煤样的晶格条纹呈现不同特征,按条纹长度分别归属于1×1-8×8共计八个类型。以3×3为临界点,在1×1和2×2中,ML-8中芳香层片的比例高于DP-4和XM-3;在3×3-8×8中,ML-8中芳香层片的比例低于DP-4和XM-3。对比HRTEM和XRD参数d002发现,随着镜质组反射率的增加d002都呈现递减趋势。