A study of the transition of liquid-crystal alignment from homeotropic to planar on a polyimide layer

The alignment of nematic liquid crystals by rubbed polyimide surfaces has been well-studied and developed. A novel polyimide film which induced a homeotropic alignment of the nematic liquid crystal without rubbing or with weak rubbing strength was presented. However, there was a transition from homeotropic to planar alignment of the nematic liquid crystal after strong rubbing. In order to study the transition, the polyimide surface was investigated by atomic force microscopy, surface free energy measurement and angle-resolved analysis X-ray photo-electron spectroscopy before and after rubbing with a velvet fabric. It was found that both the change of surface polarity and surface morphology were not the reasons for the transition. The droop of the side chain on the polyimide surface after the rubbing treatment was detected by angle-resolved analysis X-ray photo-electron spectroscopy. Owing to the special structure of the novel polyimide, the X-ray photo-electron spectroscopy was successfully used for the first time to analyse the conformational change of the side chain of a polymer. In conclusion, the transition of nematic liquid crystal alignment from homeotropic to planar after rubbing was influenced by the side chain conformation of the polyimide.     

In situ self-assembly synthesis of gold nanoparticle arrays on polystyrene microspheres and their surface plasmon resonance

Gold (Au) nanoparticle arrays with tunable morphology and optical characteristics were synthesized by in-situ self-assembly process that occurred on the surface of aniline-modified polystyrene (PS) microspheres. The method can be used to control the growth of both single and aggregated Au nanoparticle arrays on PS microsphere surface. This method could also be adapted for synthesis of other noble metals hybrid materials, which opens exciting opportunities for their practical applications.     

Simultaneous extraction and determination of fluoroquinolones,tetracyclines and sulfonamides antibiotics in soils using optimised solid phase extraction chromatography-tandem mass spectrometry

An analytical method was developed for the simultaneous extraction and determination of 18 fluoroquinolones (FQs), tetracyclines (TCs) and sulfonamides (SAs) antibiotics from soils using solid phase extraction and liquid chromatography-tandem mass spectrometry. The soils were extracted by different solvents with the help of mechanical shaking and ultrasonic treatment at 59?kHz, followed by a strong anion exchange (SAX) cartridge to clean up soil samples and a hydrophilic lipophilic balance (HLB) cartridge as enrichment. The method was evaluated by testing the following variables: extraction solvents, the type of SPE cartridges, solvent volumes, initial spiking levels and soil types (silty clay loam and clay loam soils). The soil extraction method was validated using these two types of soils, representing two typical agricultural soils in northern China. For 2?g soil, the extraction steps with the mixture of potassium phosphate buffer and acetonitrile (ACN) (1/1, v/v, pH 3.2) provided satisfactory recoveries. In the clay loam soil, the recoveries of all the compounds were from 56% to 89% at the spiking level of 50?µg?kg^?1 soil, and from 69% to 97% at the spiking level of 200?µg?kg^?1 soil, respectively. Recoveries in silty clay loam soil were similar to that in clay loam. The method was successfully employed using soil samples collected from a farmland and afforestion area irrigated with sewage in northern China. The result indicates that trace antibiotics in sewage may accumulate in soil irrigated by river water containing sewage.     

固定床煤贫氧燃烧有机气体排放特性的GC-MS研究

在设计的可移动式固定床上对神木煤在煤颗粒尺寸为3～5mm、烟气在炉膛内的停留时间为1.76s、过量空气系数为0.4和燃烧温度分别为1100、1400和1600 K条件下进行了燃烧实验。采用气相色谱质谱联用仪(GC-MS)测试分析了烟气中有机气体的排放特性。结果显示,随着炉膛温度的升高,烟气中饱和脂肪烃的含量减少了42.98%,芳香烃含量增加了50.84%。这是由于存在的氧或含氧基团与部分饱和脂肪烃反应生成了二氧化碳和水,而芳香烃由于其氧化能力较差,在氧量不足时不容易发生氧化反应所致。     

埃罗替尼的合成

以N,N-二甲基甲酰胺和硫酸二甲酯反应生成的亚胺盐与3-乙炔基苯胺进行亲核反应及甲醇的消去,获得了制备埃罗替尼所需的重要中间体N’-(3-乙炔基苯基)-N,N-二甲基甲脒,收率为75.8%。再以此中间体与2-氨基-4,5-二(2-甲氧基乙氧基)苯甲腈通过Dimroth重排反应方便地制得了抗肿瘤药物埃罗替尼,总收率(以3-乙炔基苯胺计)为56.5%。与以往合成埃罗替尼的方法相比,该方法更经济、更绿色。     

双功能配体促进的钯催化不对称醚化和胺化反应（英文）

研究双亚砜膦配体(BiSO-P)亚砜基团的Bronsted碱性在协同催化反应中的作用.1H NMR研究表明双亚砜膦与醇和胺等质子试剂形成氢键;并将此类配体应用于钯催化的不对称醚化和胺化反应,最高获得99%ee.研究发现氢键的存在能有效提高反应的ee值,配体亚砜基团在反应过程中同时起着Lewis和Bronsted碱的作用.     

Synthesis of high molecular weight and narrow molecular weight distribution poly(acrylonitrile) via RAFT polymerization

Well‐defined polyacrylonitrile (PAN) of high viscosity‐average molecular weight (M_η = 405,100 g/mol) was successfully synthesized using reversible addition‐fragmentation chain transfer polymerization. The polymerization exhibits controlled characters: molecular weights of the resultant PANs increasing approximately linearly with monomer conversion and keeping narrow molecular weight distributions. The addition of 0.01 equiv (relative to monomer acrylonitrile) of Lewis acid AlCl₃ in the polymerization system afforded the obtained PAN with an improved isotacticity (by 8%). In addition, the influence of molecular weights and molecular weight distributions of PANs on the morphology of the electrospun fibers was investigated. The results showed that, under the same conditions of electrospinning, average diameter (247–1094 nm) of fibers increased with molecular weights of PANs, and it was much easier to get “uniform” diameter fibers while using PANs with narrow molecular weight distributions as the precursor of electrospinning. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Studies on the Synthesis and Antiproliferative Activities of 13‐cis‐Retinoyl Sugar Derivatives

New retinoyl sugar derivatives of 13‐cis‐retinoic acid were synthesized in three ways in this paper in order to enhance pharmacal effects, especially antiproliferative activities of 13‐cis‐retinoic acid. Their structures were confirmed by IR, ¹H‐NMR, ¹³C‐NMR, and MS spectra and their antiproliferative activities were determined in vitro using human cancer lines. Results showed that some compounds possessed potential antitumor activities.     

Terbinafine hydrochloride intercalated in montmorillonite: synthesis and characterization

The novel antifungal hybrid of terbinafine hydrochloride (TER-HCl)/montmorillonite was synthesized by the intercalation method under mechanical stirring. Intercalation of TER-HCl in the MMT galleries was characterized by X-ray diffraction (XRD), Fourier transform infrared spectra, elemental analysis (EA). and thermogravimetric analysis (TGA). The results from IR, TGA, and EA showed a difference in chemical composition of the MMT and the TER-HCl/MMT. XRD analysis showed that the basal spacing of montmorillonite significantly expanded from 1.53 to 2.79 nm. TER-HCl was successfully intercalated into the interlayer of MMT, and 28 % of TER-HCl was released after 48 h in 0.9 % (w/v) NaCl aqueous solution (pH 7) at 37 ± 0.5 °C. The antifungal activity of the hybrid against Candida albicans was evaluated using the inhibitory zone method and the minimum inhibitory concentration. The TER-HCl/MMT strongly inhibited C. albicans. These results show that TER-HCl/MMT can be useful in biomedical applications.     

Excellent degradation performance of azo dye by metallic glass/titanium dioxide composite powders

The metallic glass/titanium dioxide powders (MG/TiO₂) with enhanced photocatalytic oxidation activity were synthesized, which exhibit a higher efficiency in decolorizing methylene blue solutions (MB). Compared with the pure TiO₂ and crystalline alloy/TiO₂ (CA/TiO₂) under the same circumstances, its degradation rate was 60 % and 30 % higher, respectively. Furthermore, compared with the CA/TiO₂, the MG/TiO₂ photocatalytic rate was three times faster when decolorizing MB. Considering the excellent intrinsic high-performance photocatalytic degradation under visible light irradiation, these novel powders were proven to have potential applications in water purification industry.