Synthesis of sterically hindered antipyrines for intramolecular charge transfer facilitated sensing

A new series of sterically hindered antipyrine derivatives have been synthesized by Schiff base condensation for potential fluorescence sensing applications. Their optical, thermal, and electrochemical properties were fully characterized. Broad absorption spectra were observed as a result of the strong intramolecular charge transfer between antipyrine and sterically hindered conjugated moiety. Reversible one electron oxidation couple was observed for most compounds, with carbazole, phenothiazine, and bithiophene functionalized derivatives exhibiting extra reversible one one‐electron oxidation process at higher positive potentials. Cabazole functionalized antipyrine derivative APCZ presents good fluorescence sensing for Co²⁺ and Cu²⁺, with 3.41‐fold enhancement in fluorescence intensity and 2‐fold enhancement in fluorescence quantum yield observed. Copyright © 2012 John Wiley & Sons, Ltd.     

支链醇对Gemini表面活性剂表面活性和胶束化行为的影响

Gemini表面活性剂是一类高效的新型表面活性剂,而醇是工业界和日化领域最常采用的表面活性剂助剂,因此研究不同结构的醇对Gemini表面活性剂表面活性和胶束化行为的影响规律和机理对于促进Gemini表面活性剂的发展和实际应用具有重要意义.利用表面张力、电导、等温滴定微量热,低温透射电镜和核磁共振研究了直链醇1-戊醇和具有相同主链的支链醇2-己醇与3-庚醇对具有不同长度连接基团阳离子季铵盐型Gemini表面活性剂C₁₂C_SC₁₂Br₂ （S=2,4,6,8,10,12）的表面活性和胶束化行为的影响,结果发现,支链醇能够显著影响表面活性剂在气/液界面的排布,使得C₂₀ （使溶剂的表面张力降低20 mN/m所需的表面活性剂浓度）和γ_CMC （CMC时表面张力值）随醇支化度的增加而显著降低,而支链醇对表面活性剂在溶液中的临界胶束浓度以及胶束的尺寸和形貌均没有明显影响,同时这些醇对Gemini表面活性剂的影响与连接基团的长度相关.阐述了上述结果产生的机理,将有助于指导如何选择合适结构的醇助剂去调控Gemini表面活性剂的表面和溶液性质.     

Phase relations of the (Pr1−xSmx)2Fe14B system

The phase relations in the (Pr_1?xSm_x)₂Fe₁₄B system in a whole concentration range have been studied by means of X-ray powder diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). The XRD patterns of the (Pr_1?xSm_x)₂Fe₁₄B samples have been refined by Rietveld method. These results reveal that all the alloys (Pr_1?xSm_x)₂Fe₁₄B are similar to the end member of the investigated system Pr₂Fe₁₄B with tetragonal structure (space group P4₂/mnm). The continuous solid solutions were formed in this system. The normalized lattice parameters and unit cell volumes of (Pr_1?xSm_x)₂Fe₁₄B solid solutions decrease linearly with x ranging from 0 to 1.0. The DTA measurements show that the peritectic temperature of (Pr_1?xSm_x)₂Fe₁₄B increases with increasing Sm content and no metastable phases are detected. Based on the DTA data, SEM–EDS and XRD results, the vertical section of Pr₂Fe₁₄B–Sm₂Fe₁₄B in the Pr–Sm–Fe–B system has been constructed.     

Cyclopentadithiophene based branched polymer electrets synthesized by friedel–crafts polymerization

In this report, the BF₃·Et₂O catalyzed Friedel–Crafts polymerization of cyclopentadithiophene monomers for branched conjugation‐interrupted polymer electrets with the potential application in OFET memories were demonstrated. Branched polycyclopentadithiophenes with controlled molecular weights (M_n) of approximately 8800 g/mol and narrow polydispersity index (PDI = 1.08–1.49) were obtained through the optimized polymerization temperature and time, and monomer addition strategy. OFET memories by using the synthesized polymers as the electret layers were fabricated and exhibited multilevel flash memory behaviors, wide memory windows, high on/off ratios, and long retention lifetime. Impressively, due to the strong hydrophobic, extended pi‐conjugation and electron‐donating properties, the branched polycyclopentadithiophene based OFET memory exhibited much lower programming voltage than other branched polymer electrets based devices. It is expected that the branched polycyclopentadithiophenes probably have potential application in other organic electronic devices. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3140–3150     

Dual-bioactivity-based liquid chromatography-coupled quadrupole time-of-flight mass spectrometry for NF-κB inhibitors and β2AR agonists identification in Chinese Medicinal Preparation Qingfei Xiaoyan Wan

Traditional Chinese medicine (TCM) preparations have been used as an effective multitarget strategy for the treatment of complex diseases; however, their bioactive constituents are undefined and difficult to identify. In this study, a simple and dual-target method based on ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry combined with dual-bioactive (NF-κB and β₂-adrenergic receptor) luciferase reporter assay systems was developed for the rapid determination of various bioactive compounds of TCM preparations. Qingfei Xiaoyan Wan, a TCM preparation used for the clinical therapy of asthma, was analyzed with this method. Potential anti-inflammatory and spasmolytic constituents were screened using NF-κB and β₂-adrenergic receptor activity luciferase reporter assay systems and simultaneously identified according to the time-of-flight mass spectrometry data. One β₂-adrenergic receptor agonist (ephedrine) and four structural types of NF-κB inhibitors (arctigenin derivatives, cholic acid derivatives, chlorogenic acid, and sinapic acid) were characterized. Tracheloside was considered a new NF-κB inhibitor. Further cytokine and chemokine detection confirmed the anti-inflammatory effects of the potential NF-κB inhibitors. The integration of ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry and dual-bioactive human cell functional evaluation systems proved to be a simple and effective strategy for the rapid screening of various bioactive compounds in TCM preparations used to treat complex diseases.     

Two new C-glucoside oxanthrones from Rumex gmelini

Two new C-glucoside oxanthrones,6-methoxyl-10-hydroxyaloin A(1) and 6-methoxyl-10-hydroxyaloin B(2),were isolated from the roots of Rumex gmelini Turcz.Their structures were elucidated on the basis of spectroscopic techniques and chemical means.     

2-硫代巴比妥酸修饰金纳米探针高灵敏比色检测三聚氰胺

以2-硫代巴比妥酸(TBA)修饰金纳米粒子为探针,TBA与三聚氰胺通过氢键作用诱导金纳米探针团聚,进而使金纳米胶体颜色由酒红色变为蓝色。 实验优化得最佳反应条件为在乙酸缓冲溶液（pH=7.0）介质中,室温反应15 min。 对不同浓度三聚氰胺进行检测时发现,在0.062~0.18 μmol/L和0.18~6.0 μmol/L之间,A660/A520吸收比率与三聚氰胺浓度呈现良好的线性关系,检出限为0.043 μmol/L。 该方法用于检测牛奶样品中的三聚氰胺的加标回收率为102.8%～105.3%。     

Reconstruction of Covalent Organic Frameworks by Dynamic Equilibrium

Covalent organic frameworks (COFs) are periodic two‐ or three‐dimensional polymeric networks with high surface areas, low density, and designed structures. Because COFs are normally prepared based on reversible formation of covalent bonds with relatively weak stability, their structures can be easily broken or damaged due to changes in the surrounding environment. Thus, developing strategies to realize the reconstruction of COFs in order to extend their usage lifetime is crucial for practical applications. In addition, exploring the kinetics of COF growth under varied reaction conditions is important for better understanding the nucleation and growth processes of COFs. In this work, the reformation mechanism of an imine‐based COF using an ex situ characterization method was investigated, disclosing an interesting COF reconstruction progress from disorder to order. The present study shows the regeneration ability of COFs, and the developed method could be generalized for broader use in the field.     

我国大病保险最优补偿分段方式与区间数量研究

我国大病保险补偿方案制定中,分段的方式以及区间的数量尤为重要.本文在区间等分、等比递增和等比递减三种分段方式下,分别建立以区间数量为自变量,以大病保险补偿额度为因变量的理论模型.以期望补偿比例作为衡量大病保险补偿水平的标准,在不低于95%的期望补偿比例下,理论结果显示:(i)区间等分、等比递增和等比递减三种分段方式对应的最佳区间数量分别为3个、3个和5个;(ii)在设定前述最优区间数量时,区间等比递增模式的补偿水平最高,其次为区间等比递减模式,区间等分模式的补偿水平最低,但是三者相差不大.接着,基于2015年的CHARLS数据为实证,计算三种区间分段方式下,家庭灾难性医疗支出发生率依次为7.13%、7.26%和7.69%,与理论的结果一致.     

Recent Progress of the Beijing FEL──Realized Saturated Oscillation

Beijing FEL facility has been built in IHEP,the saturated oscillation has been obtained at a wavelength of 10.68μm,on Dec.28,1993.The average output energy and the pulse width were measured respectively to be 3mJ,2μs.The corresponding osillation power is greater than 210kW,peak power is about 20MW, which is about 10⁸ times higher than that of spontaneous emission. The FWHM of the FEL spectracal bandwidth is less than 2%.The small signal net gain is 24% per pass.The extraction efficiency is 0.45%.In the present experimental resules,BFEL can be saturated by changing electron energy at the wavelength range from 9-10μm,the maxmium average output energy and extraction efficiency are 10mJ,0.52% respectively,the minimum spectral bandwidth of 0.3% has achieved by shorting cavity length.