聚甲基乙撑碳酸酯/天然高分子复合材料研究进展

聚甲基乙撑碳酸酯(PPC)是一种新型热塑性脂肪族聚碳酸酯,具有良好的生物降解性、高阻隔性和生物相容性等优点,但其热性能和力学性能较差,通过物理和化学方法改性是提高其性能的重要研究方向之一。本文综述了近年来采用淀粉、纤维素和甲壳素等天然高分子对PPC的改性研究,尤其是天然高分子含量和预处理方法等对复合材料性能的影响,并对PPC/天然高分子复合材料的发展作了总结和展望。     

HPLC-ESI/MS分析对苯二甲酸和1,3-丙二醇酯化反应产物(英文)

报道了对苯二甲酸(TPA)与1,3-丙二醇(PDO)在SO42-/6TiO2-ZrO2催化剂作用下发生的酯化反应。使用高效液相色谱-电喷雾电离质谱对酯化反应产物的成份进行了分析。分析结果表明:主要的物质是对苯二甲酸-1,3-丙二醇单酯(HPCBA)形成的二聚体和环状二聚体,也有较多的HPCBA形成的三聚体。有少量的可能没有端羟基和端羧基的未知结构物质。本文章研究结果对于TPA和PDO缩聚获得高分量的聚对苯二甲酸-1,3-丙二醇酯(PTT)具有指导作用。     

凹凸棒土应用于水样中铜和铅测定的研究

本文以凹凸棒土为固相萃取剂,与火焰原子吸收光谱(FAAS)法联用,富集并检测样品中的痕量金属离子。研究了凹凸棒土对痕量Cu(Ⅱ)和Pb(Ⅱ)的吸附作用,考察了吸附时间、凹凸棒土加入量等影响其吸附和解吸的主要因素、并考察了静态饱和吸附容量,及共存离子的影响。结果表明,当pH 6.0、凹凸棒土用量为0.25 g时,凹凸棒土对Cu(Ⅱ)和Pb(Ⅱ)的吸附率达到90.3%和92.1%;用20 mL 0.1 mol.L-1的HNO3可将吸附在凹凸棒土上的Cu(Ⅱ)和Pb(Ⅱ)定量洗脱。凹凸棒土对Cu(Ⅱ)和Pb(Ⅱ)的静态饱和吸附容量分别为15.8 mg.g-1、23.7 mg.g-1;本法对Cu(Ⅱ)和Pb(Ⅱ)的检出限分别为2.80μg.L-1、0.25μg.L-1;相对标准偏差分别为1.9%和2.1%(Cu(Ⅱ)、Pb(Ⅱ):0.40μg.mL-1,n=5)。在优化的实验条件下,实测了水样中Cu(Ⅱ)和Pb(Ⅱ)的含量,加标回收率均在96%～105%之间,结果令人满意。     

A DFT study of cage compounds: 3, 5, 8, 10, 11, 12-hexanitro-3, 5, 8, 10, 11, 12-hexaazatetracyclo [5.5.1.12,6.04,9] dodecane and its derivatives as high energetic materials

A new cage compound, 3, 5, 8, 10, 11, 12-hexanitro-3, 5, 8, 10, 11, 12-hexaazatetracyclo [5.5.1.1^2,6.0^4,9] dodecane (HNHATCD, I) as well as its –ONO₂ (II) and –N₃ (III) derivatives were proposed in the present work. Their molecular structures were optimized at the B3LYP/6-31G(d,p) level of density functional theory. Heat of formation, strain energy, detonation performance, and thermal stability were studied. Results show that the –N₃ group greatly increases the heat of formation, but decreases the strain energy and density, and it is much more helpful for enhancing the detonation energy than the –NO₂ and –ONO₂ groups. An analysis of bond dissociation energies (BDEs) of the weakest bonds implies that the BDE of –N₃ derivatives is the smallest but it is still larger than 120 kJ mol^?1, revealing that these designed compounds have a high thermal stability. Considering the detonation performance and thermal stability, I and II may be potential candidates of high energy density materials.     

Modified capillary electrophoresis based measurement of the binding between DNA aptamers and an unknown concentration target

The recognition of targets such as biomacromolecules, viruses and cells by their aptamers is crucial in aptamer-based biosensor platforms and research into protein function. However, it is difficult to evaluate the binding constant of aptamers and their targets that are hard to purify and quantify, especially when the targets are undefined. Therefore, we aimed to develop a modified capillary electrophoresis based method to determine the dissociation constant of aptamers whose targets are hard to quantify. A protein target, human thrombin, and one of its aptamers were used to validate our modified method. We demonstrated that the result calculated by our method, only depending on the aptamer’s concentrations, was consistent with the classical method, which depended on the concentrations of both the aptamers and the targets. Furthermore, a series of DNA aptamers binding with avian influenza virus H9N2 were confirmed by a four-round selection of capillary electrophoresis–systematic evolution of ligands by exponential enrichment, and we identified the binding constant of these aptamers by directly using the whole virus as the target with the modified method. In conclusion, our modified method was validated to study the interaction between the aptamer and its target, and it may also advance the evaluation of other receptor–ligand interactions.     

Identification of urinary metabolites of imperatorin with a single run on an LC/Triple TOF system based on multiple mass defect filter data acquisition and multiple data mining techniques

The detection of drug metabolites, especially for minor metabolites, continues to be a challenge because of the complexity of biological samples. Imperatorin (IMP) is an active natural furocoumarin component originating from many traditional Chinese herbal medicines and is expected to be pursued as a new vasorelaxant agent. In the present study, a generic and efficient approach was developed for the in vivo screening and identification of IMP metabolites using liquid chromatography-Triple TOF mass spectrometry. In this approach, a novel on-line data acquisition method mutiple mass defect filter (MMDF) combined with dynamic background subtraction was developed to trace all probable urinary metabolites of IMP. Comparing with the traditionally intensity-dependent data acquisition method, MMDF method could give the information of low-level metabolites masked by background noise and endogenous components. Thus, the minor metabolites in complex biological matrices could be detected. Then, the sensitive and specific multiple data-mining techniques extracted ion chromatography, mass defect filter, product ion filter, and neutral loss filter were used for the discovery of IMP metabolites. Based on the proposed strategy, 44 phase I and 7 phase II metabolites were identified in rat urine after oral administration of IMP. The results indicated that oxidization was the main metabolic pathway and that different oxidized substituent positions had a significant influence on the fragmentation of the metabolites. Two types of characteristic ions at m/z 203 and 219 can be observed in the MS/MS spectra. This is the first study of IMP metabolism in vivo. The interpretation of the MS/MS spectra of these metabolites and the proposed metabolite pathway provide essential data for further pharmacological studies of other linear-type furocoumarins.     

Magnetic separation of heavy metal ions and evaluation based on surface‐enhanced Raman spectroscopy: Copper(II) ions as a case study

A new approach was developed for the magnetic separation of copper(II) ions with easy operation and high efficiency. p‐Mercaptobenzoic acid served as the modified tag of Fe₂O₃@Au nanoparticles both for the chelation ligand and Raman reporter. Through the chelation between the copper(II) ions and carboxyl groups on the gold shell, the Fe₂O₃@Au nanoparticles aggregated to form networks that were enriched and separated from the solution by a magnet. A significant decrease in the concentration of copper(II) ions in the supernatant solution was observed. An extremely sensitive method based on surface‐enhanced Raman spectroscopy was employed to detect free copper(II) ions that remained after the magnetic separation, and thus to evaluate the separation efficiency. The results indicated the intensities of the surface‐enhanced Raman spectroscopy bands from p‐mercaptobenzoic acid were dependent on the concentration of copper(II) ions, and the concentration was decreased by several orders of magnitude after the magnetic separation. The present protocol effectively decreased the total amount of heavy metal ions in the solution. This approach opens a potential application in the magnetic separation and highly sensitive detection of heavy metal ions.     

Separation,interconversion, and insecticidal activity of the cis‐ and trans‐isomers of novel hydrazone derivatives

A series of cis‐ and trans‐isomers of hydrazone derivatives were separated and analyzed through HPLC with diode‐array detection and HPLC‐MS/MS using ESI and ion trap MS. Two single crystals (A‐5‐1 and C‐2‐1) of the trans‐isomers were obtained and determined using X‐ray crystallography data, and the cis‐ to trans‐isomerization under different conditions was discussed. Both of the cis‐ and trans‐isomers of A‐4 and A‐5 exhibited good insecticidal activities against Plutella xylostella.     

Simultaneous determination of 11 related impurities in propofol by gas chromatography/tandem mass spectrometry coupled with pulsed splitless injection technique

A variety of related impurities, including starting materials, process impurities, and degradation products, can be detected in propofol. In this article, a sensitive and selective GC‐MS/MS method using pulsed splitless injection technique for the determination of 11 main related impurities in propofol in one chromatogram is investigated. This method is extensively validated for its linearity, recovery, precision, LOD, and LOQ, and is able to detect trace‐level related impurities (LOD = 0.2–5.6 μg/g) in propofol bulk drug. Stressed tests proposed that oxidative degradation, photolytic degradation, and heat are the main causes for the formation of degradation products in propofol.