Dendrimer as nanocarrier for drug delivery

Dendrimers are novel three dimensional, hyperbranched globular nanopolymeric architectures. Attractive features like nanoscopic size, narrow polydispersity index, excellent control over molecular structure, availability of multiple functional groups at the periphery and cavities in the interior distinguish them amongst the available polymers. Applications of dendrimers in a large variety of fields have been explored. Drug delivery scientists are especially enthusiastic about possible utility of dendrimers as drug delivery tool. Terminal functionalities provide a platform for conjugation of the drug and targeting moieties. In addition, these peripheral functional groups can be employed to tailor-make the properties of dendrimers, enhancing their versatility. The present review highlights the contribution of dendrimers in the field of nanotechnology with intent to aid the researchers in exploring dendrimers in the field of drug delivery.     

基于傅里叶变换-离子回旋共振质谱的离子碰撞截面测量方法及应用

傅里叶变换-离子回旋共振质谱（FT-ICR MS）具有较高的分辨率和串联质谱分析能力。离子在分析池中做回旋运动时,镜像电流会因离子与中性分子发生碰撞而逐渐衰减。基于此,通过选择合适的理论模型,并结合相应的算法,可推算出离子的碰撞截面（CCS）。该方法无需增加仪器硬件成本,可通过直接分析高分辨质谱数据获取离子结构信息。近年来,随着FT ICR MS仪器的发展和推广,该方法得到快速发展。本文综述了此类方法使用的碰撞模型、利用时域和频域信号进行数据分析的不同方法及特点,虽然提供的离子CCS数据的可靠性和准确度有待进一步提高,但在离子的动态CCS测量以及离子异构化的研究中表现出独特优势。该方法可进一步与离子淌度技术相结合,借助FT ICR MS较高的质量分辨能力和离子操控能力,提供多维度的离子结构信息。     

Molecular composition of in-situ combustion and steam assisted gravity drainage crude oils

This study investigated the property and composition of crude oils from in-situ combustion (ISC) and steam assisted gravity drainage (SAGD). We made comparison of the elemental composition and molecular weight distribution of the two crude oils. It was overserved that ISC crude oil has significant higher oxygen content. The ultra-high resolution mass spectrometry was applied to investigate the molecular composition of acidic compounds in two crude oils. The acidic compounds in ISC crude oil have higher carbon numbers than that of SAGD crude oils.     

傅立叶变换离子回旋共振质谱仪在石油组成分析中的应用

傅立叶变换离子回旋共振质谱仪(FT-ICR MS)是一种具有超高质量分辨能力的质谱仪,在石油组分相对分子质量范围(200～1 000 u)内,其分辨率能够达到几十万甚至上百万,这种分辨能力可以精确地确定由C、H、S、N、O以及它们主要同位素所组成的各种元素组合,真正从分子元素组成层次上研究石油组成。电喷雾(ESI)电离源可以从高浓度复杂烃类基质中选择性地电离石油组分中微量的杂原子极性化合物,ESI与FT-ICR MS相结合已经成为重质油非烃化合物分析的一种重要手段。本文介绍了FT-ICR MS的基本原理及近年来的发展趋势,石油组分的电离化方法及数据处理技术,综述了近期利用FT-ICR MS对石油组成取得的新认识,以及该仪器手段在石油有机地球化学、油田化学、炼油化工等领域的应用情况。尽管在重质油组成定量分析方面还存在一些技术问题,FT-ICR MS无疑将成为石油化学研究和石油工业生产过程的重要检测工具。     

反应条件对渣油加氢产物中碱性氮化物的影响

利用间歇式固定床反应器对大连混合渣油进行催化加氢反应,研究氢分压和剂油比对加氢液体产物中碱性氮化物分布及类型的影响;利用电喷雾傅里叶变换离子回旋共振质谱（ESI FT-ICR MS）对原料油及产物中的碱性氮化物进行表征。结果表明：反应前后渣油中N1（含1个N原子）类的碱性化合物占绝大比例,N1S1（含1个N、1个S原子）和O1（含1个O原子）类化合物的比例次之,其它类型的相对丰度均较低;随氢分压的增大,产物中大部分碱性氮化物类别的丰度有所下降,同时发生了加氢断侧链致使N1类化合物分子的碳数减少,分子尺寸变小;随剂油质量比的增大,杂原子的相对丰度减弱,分子饱和度减小,N1类化合物的等效双键数（DBE）分布没有显著变化（DBE为9~18）;但加氢反应的断链使得分子碳数明显变小为C20~C34;反应后产物中杂原子明显减少。     

基于分子组成的减压渣油聚类分析

基于减压渣油的结焦性能受化合物的类型分布的影响,将高分辨质谱分析得到的数据按照芳烃（HC）、含1个硫原子的硫化物(S1)、含2个硫原子的硫化物(S2)、含1个氮原子的氮化物(N1),按碳数的分布分成10类,并从分子组成上对71种减压渣油进行了聚类分析。结果表明：聚类分析将71种减压渣油按分子组成特点分为Ⅰ类、Ⅱ类和Ⅲ类减压渣油;为验证聚类的准确性,以减压渣油的残炭值作为聚类分析结果合理性判断的依据,发现Ⅰ类减压渣油残炭值最低,属于不易结焦的减压渣油;Ⅲ类减压渣油残炭值最大,属于最易结焦的减压渣油;Ⅱ类减压渣油残炭值高于Ⅰ类减压渣油,低于Ⅲ类减压渣油,结焦倾向居中。本研究利用聚类分析对多个减压渣油样本按分子组成进行分类,实现了FT-ICR MS数据的有效管理,为减压渣油的加工提供指导。     

碰撞诱导解离技术研究减压渣油四组分中芳环结构的连接方式

The linkage of aromatic ring structures in vacuum residues was important for the refining process. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) combined with collision-induced dissociation (CID) was a powerful method to characterize the molecular structures. In this work, model compounds with different aromatic ring structures were measured by CID FT-ICR MS. The cracking of the parent ions and the generated fragment ions were able to distinguish different linkage of the model compounds. Then, vacuum residues were separated into saturates, aromatics, resins and asphaltenes fractions (SARA), and each fraction was characterized by CID technology. According to the experiment results, the aromatic rings in saturates and aromatics fractions were mainly island-type structures, while the aromatic rings in resins and asphaltenes fractions had a significant amount of archipelago-type structures.     

减压馏分油（VGO）中噻吩类硫化物的沸点分布

将噻吩类硫化物母环已有的沸点数据与经验公式相结合,得到减压馏分油（VGO）中各类硫化物在不同碳数下的沸点数据,经验公式计算得到的沸点数据与已知的沸点数据基本吻合。采用傅里叶变换离子回旋共振质谱(FT ICR MS)测得了大庆、胜利、辽河、塔河4种原油的直馏VGO馏分中噻吩类硫化物的详细碳数和类型分布。结合FT ICR MS质谱数据和各类硫化物的沸点数据,可以得到硫化物的沸点分布。使用气相色谱 硫化学发光检测器(GC SCD)对FT ICR MS所得到的硫化物沸点分布结果进行校正,得到了与实际蒸馏温度相一致的硫化物沸点分布。由于FT ICR MS可以区分不同类型的硫化物,因此进一步给出了这4种VGO中噻吩类、苯并噻吩类、二苯并噻吩类以及苯并萘并噻吩类硫化物的沸点分布,可以为重油脱硫工艺的开发和改进提供依据。     

Origin of the unusually high dibenzothiophene concentrations in Lower Ordovician oils from the Tazhong Uplift, Tarim Basin, China

The origin of the unusually high dibenzothiophene (DBT) concentrations in Lower Ordovician oils from the Tazhong Uplift,Tarim Basin was studied by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS).The most abundant sulfur compounds in the oils are S 1 species with doublebond equivalent (DBE) values of 1-19 and 11-48 carbon atoms.The range of the number of carbon atoms in the sulfur compounds detected by the FT-ICR MS (S 1 species with DBE=9) is about ten times larger than that for sulfur compounds detected by GC/MS (DBTs).This suggests that FT-ICR MS is a much better approach than GC/MS for characterization of DBTs in crude oils.The abundance of S 1 species with DBE=1-8 decreased with increasing thermal maturity,while the abundance of S 1 species with DBE=9 (primarily DBTs) increased.Therefore,thermal maturity is an important factor in the formation of oils with high DBT concentrations.Unusually high abundances of S 1 species with low DBE values (1-8),which include sulfide,thiophene and benzothiophene,were observed in several oils,especially the TZ83 (O 1) oil with high or very high thermal maturity.Thermochemical sulfate reduction (TSR) was thought to be the reason for the high abundance of these low DBE compounds in deep reservoirs,and thermochemical sulfate reduction could affect the distribution and composition of DBTs in the oils.According to the results of FT-ICR MS analysis,there are no signs that TSR is occurring or has occurred recently for most of the Lower Ordovician oils.     

A Study on the Distribution of Nitrogen-containing Compounds From Liaohe Atmospheric Residue

The distribution of nitrogen (N)-containing compounds of Liaohe Atmospheric Residue (LHAR) was investigated. The compounds were analyzed by GC-MS and ESI FT-ICR MS. It is demonstrated that the basic nitrogen compounds in LHAR consist mainly of quinoline compounds and a part of pyridine and acridine compounds, while the main nonbasic nitrogen compounds are carbazole and indole compounds. And the major N-compounds are N₁ compounds with unsaturation between 7 and 15 and carbon numbers between 25 and 35. With the rising of boiling point, the carbon numbers and unsaturation increase, meanwhile, N₁O₂ and N₁O₁ heteroatomic compounds gradually appear. For the vacuum fractions of LHAR, as the boiling point rises, the content of basic nitrogen compounds reduces and none-basic nitrogen compounds increases gradually.