单纤维实验技术的现状和展望

本文综述了目前流行的测量纤维／树脂界面力学性能的单纤维实验技术。重点介绍了三种单纤维实验技术——单纤维拔出法、单纤维段埋入法和单纤维压出法的基本原理。讨论了三种单纤维实验技术在理论和应用上的发展重点     

氮气中六氟化硫气体标准物质的研制

建立了制备氮气中六氟化硫气体标准物质的方法。以称量法制备气体标准物质并计算定值,采用气相色谱法对制备的气体标准物质的均匀性和稳定性进行考察。将所制备的标准物质与中国计量院提供的氮气中六氟化硫气体标准物质进行比对分析验证,确保了气体标准物质量值的准确可靠。结果表明,所研制的浓度为10μL/L的氮气中六氟化硫气体标准物质定值的扩展不确定度为2%,贮存有效期为1年,完全能够满足电力部门仪表的检定与校准要求。     

隐身材料微波隐身特性评估方法

列举了隐身材料微波电磁参数、反射率、目标雷达散射截面(RCS)的测试方法和相关标准,重点介绍了探头法、谐振腔法、传输反射法、自由空间等电磁参数测量方法及弓形法、远场法等反射率测试方法的基本原理和测试装置,分析了各种方法的特点和适用范围。     

Enzymatic‐catalyzed polymerization of water‐soluble electrically conductive polymer PEDOT:PSS

Water‐soluble electrically conductive polymer poly(3,4‐ethylenedioxythiophene) (PEDOT) was synthesized by the enzymatic‐catalyzed method using 3,4‐ethylenedioxythiophene (EDOT) as monomer, poly(styrenesulfonate) (PSS) as water‐soluble polyelectrolyte, horseradish peroxidase enzyme as catalyst, and hydrogen peroxide (H₂O₂) as oxidant. Fourier transform infrared spectra and UV–vis absorption spectra confirm the successful enzymatic‐catalyzed polymerization of PEDOT. Dynamic light scattering data confirm the formation of a stable PEDOT:PSS aqueous dispersion. The thermo gravimetric data show that the obtained PEDOT is stable over a fairly high range of temperatures. The atomic force microscopy height images show that the PEDOT:PSS aqueous dispersion can form excellent homogeneous and smooth films on various substrates by conventional solution processing techniques, which renders this PEDOT:PSS aqueous dispersion a very promising candidate for various application in electronic devices. This enzymatic polymerization is a new approach for the synthesis of optical and electrical active PEDOT polymer, which benefits simple setting, high yields, and environmental friendly route. Copyright © 2014 John Wiley & Sons, Ltd.     

Improvement of the chromatographic separation performance of an imidazolium ionic liquid functionalized silica column by in situ anion‐exchange with dodecyl sulfonate and dodecylbenzene sulfonate anions

The anionic part of ionic liquids can provide additional interactions during chromatographic separations. In this work, the chromatographic separation performance of a silica column functionalized with 1‐propyl‐3‐methylimidazolium chloride ionic liquid was improved by in situ anion‐exchange from chloride anions to dodecyl sulfonate anions and dodecylbenzene sulfonate anions. The separation performances of these ionic liquid functionalized phases were investigated and compared with each other using polycyclic aromatic hydrocarbons, phthalates, parabens, and phenols as model compounds. Results indicated that the new columns presented a better chromatographic separation than the original one. This was ascribed retention mechanism from organic anions. The introduction of dodecyl sulfonate anions increased the hydrophobicity of stationary phase. Furthermore, the phenyl groups of dodecylbenzene sulfonate anions could provide an enhanced selectivity to aromatic compounds such as polycyclic aromatic hydrocarbons by π–π interactions. Analysis repeatability of the new columns was satisfactory (RSD of retention time, 0.10–0.40%; RSD of peak area, 0.66–0.84%).     

Dicationic imidazolium ionic liquid modified silica as a novel reversed‐phase/anion‐exchange mixed‐mode stationary phase for high‐performance liquid chromatography

A dicationic imidazolium ionic liquid modified silica stationary phase was prepared and evaluated by reversed‐phase/anion‐exchange mixed‐mode chromatography. Model compounds (polycyclic aromatic hydrocarbons and anilines) were separated well on the column by reversed‐phase chromatography; inorganic anions (bromate, bromide, nitrate, iodide, and thiocyanate), and organic anions (p‐aminobenzoic acid, p‐anilinesulfonic acid, sodium benzoate, pathalic acid, and salicylic acid) were also separated individually by anion‐exchange chromatography. Based on the multiple sites of the stationary phase, the column could separate 14 solutes containing the above series of analytes in one run. The dicationic imidazolium ionic liquid modified silica can interact with hydrophobic analytes by the hydrophobic C₆ chain; it can enhance selectivity to aromatic compounds by imidazolium groups; and it also provided anion‐exchange and electrostatic interactions with ionic solutes. Compared with a monocationic ionic liquid functionalized stationary phase, the new stationary phase represented enhanced selectivity owing to more interaction sites.     

Lipidomic profiling of plasma in patients with chronic hepatitis C infection

Chronic hepatitis C virus (HCV) infection is a global health issue. Although its progression is reported to be closely associated with lipids, the way in which the plasma lipidome changes during the development of chronic HCV infection in humans is currently unknown. Using an improved quantitative high-throughput lipidomic platform, we profiled 284 lipids in human plasma samples obtained from healthy controls (n?=?11) and patients with chronic HCV infection (n?=?113). The intrahepatic inflammation grade (IG) of liver tissue was determined by biopsy. Two types of mass spectrometers were integrated into a single lipidomic platform with a wide dynamic range. Compared with previous methods, the performance of this method was significantly improved in terms of both the number of target sphingolipids identified and the specificity of the high-resolution mass spectrometer. As a result, 44 sphingolipids, one diacylglycerol, 43 triglycerides, 24 glycerophosphocholines, and 5 glycerophospho-ethanolamines were successfully identified and quantified. The lipid profiles of individuals with chronic HCV infection were significantly different from those of healthy individuals. Several lipids showed significant differences between mild and severe intrahepatic inflammation grades, indicating that they could be utilized as novel noninvasive indicators of intrahepatic IG. Using multivariate analysis, healthy controls could be discriminated from HCV patients based on their plasma lipidome; however, patients with different IGs were not well discriminated. Based on these results, we speculate that variations in lipid composition arise as a result of HCV infection, and are caused by HCV-related digestive system disorders rather than progression of the disease.

High-sensitivity PCR method for detecting BRAF V600Emutations in metastatic colorectal cancer using LNA/DNA chimeras to block wild-type alleles

The response to epidermal growth factor receptor (EGFR)-targeted therapy in metastatic colorectal cancer (mCRC) is variable because of intra-tumor heterogeneity at the genetic level, and consequently, it is important to develop sensitive and selective assays to predict patient responses to therapy. Low-abundance BRAF V600E mutations are associated with poor response to treatment with EGFR inhibitors. We developed a method for the detection of BRAF V600E mutations in mCRC using real-time wild-type blocking PCR (WTB-PCR), in which a chimera composed of locked nucleic acids and DNA is incorporated to amplify the mutant allele at high efficiency while simultaneously inhibiting the amplification of wild-type alleles. Mixing experiments showed that this method is exquisitely sensitive, with detection of the mutated allele at a mutant/wild-type ratio of 1:10,000. To demonstrate the applicability of this approach for mCRC patients, we assessed the V600E mutations in 50 clinical cases of mCRC by real-time WTB-PCR. The percentage of patients with V600E mutation as determined by WTB-PCR (16 %, 8/50) was higher than by traditional PCR (10 %, 5/50), suggesting an increased sensitivity for WTB-PCR. By calculating the ΔC _q for real-time traditional PCR, which amplifies all BRAF alleles, versus WTB-PCR, which selectively amplifies mutant BRAF, we demonstrated that among the V600E-positive mCRC patient samples, the percentage of BRAF DNA with the V600E mutation ranged from 0.05 to 52.32 %. In conclusion, WTB-PCR provides a rapid, simple, and low-cost method to detect trace amounts of mutated BRAF V600E gene.     

Biocatalytic desymmetrization of 3-substituted glutaronitriles by nitrilases. A convenient chemoenzymatic access to optically active (S)-Pregabalin and (R)-Baclofen

<正>1 General procedure for the preparation of 3-substituted glutaronitriles To a 100 mL flask containing aldehyde(30 mmol) and cyanoacetic acid(10.20 g, 120 mmol) was added 4-methylpiperidine(0.4 mL) and 23 mL N-methylmorpholine. The reaction mixture was warmed to mild reflux for 24 h and then cooled to room temperature and concentrated on a rotary evaporator. The resulting mixture was dissolved in 100