开放骨架磷酸铝AlPO4-12的晶化过程

以乙二胺为结构导向剂,在200℃加热物质的量组成为nAl₂O₃:nP₂O₅:n_en:nH₂O=1:1:2:226的初始混合物(en=乙二胺),合成了三维开放骨架磷酸铝化合物AlPO₄-12。用X-射线衍射、元素分析、pH测量、液体核磁共振以及电喷雾质谱研究了其晶化过程。依据质谱数据,开发了一个系统枚举在晶化过程中可能生成的小结构单元分子式的方法。研究发现在AlPO₄-12的晶化过程中经历了层状磷酸铝UiO-15和UiO-13中间相,液相中Al物种的浓度极低,在晶化过程中生成的小结构单元中P-OH逐渐增多,乙二胺分子逐渐质子化,在晶化过程中生成了磷酸铝的4元环和6元环。用电喷雾质谱研究晶化过程中的液相可以获得小结构单元的结构和组成信息。     

Controlling the optimum surfactants concentrations for dispersing carbon nanofibers in aqueous solution

As a new nano-scale functional material, it is necessary to achieve a uniform distribution in the composites for gaining the CNFs’ excellent reinforcing effect. In this paper, CNFs were purified by the method of high temperature annealing treatment. Six surfactants, methylcellulose (MC), hydroxypropyl methylcellulose (HPMC), sodium dodecyl sulfate (SDS), dodecylamine (DDA), N, N-dimethyl formamide (DMF) and cetyltrimethyl ammonium bromide (CTAB) were used individually and combinatorially in a certain concentration to disperse the CNFs in aqueous solution. To achieve a good dispersion of the CNFs, a method utilizing ultrasonic processing was employed. The CNFs treated by the method of high temperature annealing treatment were characterized by differential thermal analysis (DTA) and thermogravimetry analysis (TGA), and the ultrasonication-driven dispersion of CNFs in aqueous solutions were monitored by UVvis spectroscopy and transmission electron microscopy (TEM). The experiments reveal that the method of high temperature annealing treatment purified the CNFs and the maximum achievable dispersion of CNFs corresponds to the maximum UV absorbance of the solution. All results show that the surfactants mixture of MC and SDS in a certain concentration of 0.4 and 2.0 g/L has the maximum dispersion effect on CNFs in aqueous solution, the optimum concentration ratio of MC, SDS, and CNFs was 2: 10: 1.     

Copper-catalyzed dehydrogenative cross-coupling reaction between unactivated ethers and simple ketones mediated by pyrrolidine

A copper-catalyzed dehydrogenative cross-coupling reaction between unactivated ethers and simple ketones mediated by pyrrolidine has been developed. Under the catalysis of CuBr₂ and in the presence of pyrrolidine, either tetrahydrofuran 2a or tetrahydropyran 2b can react smoothly with a series of methyl aryl ketones 1a–m to give desired coupling products 3aa–mb using TBHP as an oxidant. The advantages of the dehydrogenative cross-coupling reaction are adoption of unmodified ethers as substrates, good tolerance of many functional groups and use of cheap copper salt as a catalyst. A plausible radical mechanism through enamine attack is proposed.     

表面解吸常压化学电离质谱快速鉴别樟木制品

采用自行研制的表面解吸常压化学电离质谱(SDAPCI-MS),在无需样品预处理的情况下,对樟木制品及普通木材进行检测,在正离子模式及m/z 90～400范围内获得其化学指纹图谱,并通过主成分分析(PCA)方法对所获指纹谱图信息进行分析,进而对不同样品进行鉴别。结果表明,SDAPCI-MS能够对樟木表面多种特征化学成分(樟脑,香叶醇等)进行解吸电离,快速获得樟木的化学指纹谱图,并能够对目标组分做多级串联质谱鉴定。结合PCA方法,可对不同品质、不同种类的木材样品进行区分。结果表明,本方法灵敏度高,分析速度快(单个样品分析时间小于3 min),可望应用于珍贵木材快速无损分析及品质鉴定。     

A Highly Selective and Sensitive Turn-On Fluorescent Chemosensor Based on Rhodamine 6G for Iron(III)

Recently, more and more rhodamine derivatives have been used as fluorophores to construct sensors due to their excellent spectroscopic properties. A rhodamine-based fluorescent and colorimetric Fe³⁺ chemosensor 3’,6’-bis(ethylamino)-2-acetoxyl-2’,7’-dimethyl-spiro[1H-isoindole-1,9’-[9H]xanthen]-3(2H)-one (RAE) was designed and synthesized. Upon the addition of Fe³⁺, the dramatic enhancement of both fluorescence and absorbance intensity, as well as the color change of the solution, could be observed. The detection limit of RAE for Fe³⁺ was around 7.98 ppb. Common coexistent metal ions showed little or no interference in the detection of Fe³⁺. Moreover, the addition of CN⁻ could quench the fluorescence of the acetonitrile solution of RAE and Fe³⁺, indicating the regeneration of the chemosensor RAE. The robust nature of the sensor was shown by the detection of Fe³⁺ even after repeated rounds of quenching. As iron is a ubiquitous metal in cells and plays vital roles in many biological processes, this chemosensor could be developed to have applications in biological studies.     

熔盐电化学还原二氧化碳制备碳材料研究进展北大核心CSCD

二氧化碳浓度持续升高导致的温室效应已在全球范围内引发极端天气、冰川融化等一系列生态环境问题。为降低二氧化碳含量,改善气候变暖带来的恶劣影响,研发高效、绿色、安全的二氧化碳处理技术,促进碳资源循环可持续发展刻不容缓。熔盐离子液体作为一种良好的电化学转化介质,为二氧化碳还原提供了一条极具应用前景的技术路线。综述了国内外近几年高温熔盐中二氧化碳的捕获与电化学还原的研究,简述了熔盐电沉积碳的电化学机理和热力学机制,对不同形貌高附加值碳材料:无定形碳、碳球和碳纳米管的制备进行了总结,最后对未来发展方向做出展望。     

Synthesis and properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/chitin nanocrystals composite scaffolds for tissue engineering

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/chitin nanocrystals (CNC) composite scaffolds were synthesized by the salt leaching and thermally induced phase separation (TIPS) technique. The scaffolds have porous structures with macro-pores (100-300 mm in diameters) and micro-pores (10 mm). The surface characteristics of the scaffolds were characterized by X-ray photoelectron spectroscopy (XPS) and static water contact angle measurement, and the mechanical properties were investigated by a compression test. Human adipose-derived stem cells (hADSCs) were seeded onto the PHBV/CNC scaffolds and in vitro cell culture results showed that the composite scaffolds enhanced the hADSCs adhesion, which implies that the material may have potential application in tissue engineering.     

Structure,Antibacterial Activity and Theoretical Study of the Forming Mechanism of Compound [(5-Methyl-3-oxo-2-phenyl-1H-pyrazol-4-yl)-thiophen-2-yl-methylene] Thiosemicarbazide

A new thiosemicarbazone compound derived from 1-phenyl-3-methyl-4-(2-thenoyl) pyrazolone-5(HPMTP) and thiosemicarbazide has been synthesized and characterized by IR, HNMR, MS, elemental analysis, UV and single-crystal X-ray diffraction. The compound crystallizes in monoclinic system, Cc space group with a = 7.5925(8), b = 20.263(2), c = 11.4669(13) ,  = 107.825(8)°, V = 1679.5(3) 3, Z = 4, R = 0.0316 and wR = 0.0687. The results of antibacterial activity test against Escherichia coli and Bacillus subtilis indicate that the compound possesses the same antibacterial activity as the contrast(Norfloxacin). Theoretical study of the forming mechanism to the title compound at the RHF/6-31G(d) level shows that there are two steps. The distal amino group of thiosemicarbazide is added to the 4-carbonyl group of HPMTP which forms TM. Then a dehydration reaction occurs in TM and generates a stable product PC.     

Biotransformation of iminodiacetonitrile to iminodiacetic acid by Alcaligenes faecalis cells immobilized in ACA-membrane liquid-core capsules

Biotransformation of iminodiacetonitrile (IDAN) to iminodiacetic acid (IDA) was investigated with a newly isolated Alcaligenes faecalis ZJUTBX11 strain showing nitrilase activity in the immobilized form. To reduce the mass transfer resistance and to increase the toleration ability of the microorganisms to the toxic substrate as well as to enhance their ability to be reused, encapsulation of the whole cells in alginate-chitosan-alginate (ACA) membrane liquid-core capsules was attempted in the present study. The optimal pH and temperature for nitrilase activity of encapsulated A. faecalis ZJUTBX11 cells were 7.5°C and 35°C, respectively, which is consistent with free cells. Based on the Michaelis-Menten model, kinetic parameters of the conversion reaction with IDAN as the substrate were: K _m = (17.6 ± 0.3) mmol L^?1 and V _max = (97.6 ± 1.2) μmol min^?1 g^?1 of dry cell mass for encapsulated cells and (16.8 ± 0.4) mmol L^?1 and (108.0 ± 2.7) μmol min^?1 g^?1 of dry cell mass for free cells, respectively. After being recycled ten times, the whole cells encapsulated in ACA capsules still retained 90 % of the initial nitrilase activity while only 35 % were retained by free cells. Lab scale production of IDA using encapsulated cells in a bubble column reactor and a packed bed reactor were performed respectively.