橄榄醇分子印迹聚合物的制备及评价(英文)

以橄榄醇为模板分子,α-甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酸酯(EDMA)为交联剂,甲苯和十二醇为溶剂,通过本体聚合法制备了橄榄醇分子印迹聚合物。利用平衡结合实验、扫描电镜(SEM)及红外光谱(FTIR)对分子印迹聚合物(MIP)进行了表征,并用该聚合物进行了加标麦麸中橄榄醇的固相萃取(SPE)研究。平衡结合实验表明MIP对模板分子具有更好的识别性。Scatchard分析表明对橄榄醇分子的吸附存在2类不同结合位点,其中高亲和力结合位点和低亲和力结合位点的解离常数分别为0.021和1.002 mmol/L,相应的最大表观结合量分别为18.74和135.9 μmol/g。在优化的固相萃取条件下,MIP固相萃取柱对加标麦麸中橄榄醇的回收率达到97.8%~98.8%,相对标准偏差为2.8%~4.2%(n=5),线性范围为0.1~100 mg/L,检出限(S/N=3)为0.062 mg/L。与非印迹聚合物(NIP)柱及市售聚苯乙烯/二乙烯基苯(PLS)柱相比,MIP柱的选择性更强,回收率更高,纯化效果更好。     

Ni(II) ion-imprinted solid-phase extraction and preconcentration in aqueous solutions by packed-bed columns

Solid-phase extraction (SPE) columns packed with materials based on molecularly imprinted polymers (MIPs) were used to develop selective separation and preconcentration for Ni(II) ion from aqueous solutions. SPE is more rapid, simple and economical method than the traditional liquid-liquid extraction. MIPs were used as column sorbent to increase the grade of selectivity in SPE columns. In this study, we have developed a polymer obtained by imprinting with Ni(II) ion as a ion-imprinted SPE sorbent. For this purpose, NI(II)-methacryloylhistidinedihydrate (MAH/Ni(II)) complex monomer was synthesized and polymerized with cross-linking ethyleneglycoldimethacrylate to obtain [poly(EGDMA-MAH/Ni(II))]. Then, Ni(II) ions were removed from the polymer getting Ni(II) ion-imprinted sorbent. The MIP-SPE preconcentration procedure showed a linear calibration curve within concentration range from 0.3 to 25 ng/ml and the detection limit was 0.3 ng/ml (3 s) for flame atomic absorption spectrometry (FAAS). Ni(II) ion-imprinted microbeads can be used several times without considerable loss of adsorption capacity. When the adsorption capacity of nickel imprinted microbeads were compared with non-imprinted microbeads, nickel imprinted microbeads have higher adsorption capacity. The K_d (distribution coefficient) values for the Ni(II)-imprinted microbeads show increase in K_d for Ni(II) with respect to both K_d values of Zn(II), Cu(II) and Co(II) ions and non-imprinted polymer. During that time K_d decreases for Zn(II), Cu(II) and Co(II) ions and the k′ (relative selectivity coefficient) values which are greater than 1 for imprinted microbeads of Ni(II)/Cu(II), Ni(II)/Zn(II) and Ni(II)/Co(II) are 57.3, 53.9, and 17.3, respectively. Determination of Ni(II) ion in sea water showed that the interfering matrix had been almost removed during preconcentration. The column was good enough for Ni determination in matrixes containing similar ionic radii ions such as Cu(II), Zn(II) and Co(II).     

Molecularly Imprinted Polymer with Calix[4]arene Derivative for the Recognition of Acetanilide

Two molecularly imprinted polymers binding to analgesic acetanilide were prepared using either dual functional monomers of calix[4]arene derivative and acrylamide or single monomer acrylamide, respectively. The polymers were ground, sieved and investigated by equilibrium binding experiment to evaluate their recognition properties for the template and other substrates. Scatchard analysis showed that homogeneous recognition sites were formed in the imprinted polymer matrix. Our results demonstrated that the polymer using two functional monomers exhibited better selectivity for the template. This study may open new frontiers for the development and application of imprinted polymers, such as drug separation and purification.     

替代模板分子印迹聚合物的制备及其用于人尿、牛血清和啤酒中7种双酚类物质的选择性固相萃取

以酚酞(PP)为替代模板,采用本体聚合法制备了选择性识别7种双酚类物质(BPs)的分子印迹聚合物(MIP)。将制备的PP-MIP用作固相萃取(SPE)填料,成功应用于人尿、牛血清和啤酒样品中7种BPs的分离净化。建立了同时测定人尿、牛血清和啤酒样品中的7种BPs的MIP-SPE-HPLC分析方法。3种样品中7种BPs的方法检出限范围均为1.2~2.0 μg/L。结果表明,7种BPs在0.02~2 mg/L范围内线性关系良好,相关系数(r)大于0.9998;空白样品中加标水平为100和500 μg/L的回收率范围为90.1%~107.1%,相对标准偏差(RSD)不高于8.1%。该方法简便、准确、灵敏、可靠,可用于人尿、牛血清和啤酒中7种BPs的快速检测。     

Analysis of ochratoxin A in grapes,musts and wines by LC–MS/MS: First comparison of stable isotope dilution assay and diastereomeric dilution assay methods

Ochratoxin A (OTA) exhibits potent nephrotoxic, carcinogenic and teratogenic effects and its maximum level in wines has been set to 2 μg L⁻¹ by regulation. Consequently, the analytical procedures for OTA determination in wines have to be both very sensitive and reliable. In this paper, we compared two quantification methods: the stable isotope dilution assay (SIDA) and the diastereomeric dilution assay (DIDA). For this purpose, non-natural analogues of OTA were synthesized: the labeled OTA (OTA-d₄) as a diastereomeric mixture for the SIDA and one non-natural OTA’s diastereomer (OTA-dia) for the DIDA. To quantify OTA in red grapes, musts or wines, the sample preparation was optimized using immunoaffinity column extraction and the analysis was performed by LC–MS/MS in Multiple Reaction Monitoring mode. A validation procedure in agreement with the International Organization of Vine and Wine recommendations was conducted. It appeared that SIDA quantification exhibited excellent sensitivity (LOD < 1 ng L⁻¹), accuracy (recovery = 98%), repeatability (RSD < 3%) and intermediate reproducibility (RSD < 4%) compared to quantification by DIDA. Indeed, DIDA method did not provide satisfactory results demonstrating that immunoaffinity extraction is exclusively selective for the natural OTA and not for its diastereomer, which therefore cannot be considered as a good internal standard for this particular method.     

Ni/MWCNT及镧改性Ni/MWCNT催化CO2甲烷化反应的性能

以多壁碳纳米管(MWCNT)为载体, 通过浸渍法制备了负载型镍催化剂和稀土镧改性的镍催化剂, 并对其二氧化碳甲烷化的催化性能进行了研究. 借助比表面积测试、程序升温还原(TPR)、X射线衍射(XRD)和X射线光电子能谱(XPS)等表征手段研究了稀土镧的添加对Ni/MWCNT催化剂结构和表面组成、催化剂还原性能以及CO₂甲烷化反应性能的影响. 结果表明: 稀土镧改性的Ni/MWCNT较Ni/MWCNT催化剂具有更好的CO₂甲烷化活性, 镧组分的加入提高了催化剂表面的镍物种浓度和分散度, 弱化了氧化镍与载体MWCNT之间的相互作用, 促进了氧化镍的还原, 同时提高了表面镍物种的电子密度, 增加了对反应物的吸附能力, 从而提高了其CO₂甲烷化活性. 制备过程中稀土镧的添加次序对催化性能有较明显的影响, 其活性顺序为先浸渍镧后浸渍镍制备的催化剂活性明显好于先浸渍镍后浸渍镧制备的催化剂.     

Electron energy loss spectroscopy of Pd and Pd–Au catalysts supported on multiwall carbon nanotubes

The X-ray PhotoElectron Energy Loss Spectroscopy (XP-EELS) and Reflection Electron Energy Loss Spectroscopy (REELS) were used for analysing surface layers of “as-received” and functionalised multiwall carbon nanotubes (MWCNT), and MWCNT decorated with Pd and Pd–Au particles after calcination/reduction. The decorated MWCNT were previously applied as catalysts in a reaction of formic acid electrooxidation. These spectroscopies, used as complementary methods of structural surface analysis, provide information on the energy position, intensity and full width at half maximum of the quasi-elastic peak and inelastic π and π + σ energy loss peaks. Analysing the π + σ energy loss peak, the bulk and surface C sp²/sp³ components can be separated. Functionalisation of MWCNT, catalyst reduction and Ar⁺ ion sputtering increase the C sp³ content in comparison to the “as-received” MWCNT and calcined catalysts. The intensity ratios of surface and bulk C sp³ and sp² components evaluated from the REELS π + σ energy loss peak indicate: (i) functionalisation leads to attachment of functional groups to the MWCNT surface, (ii) calcined catalysts show an amorphous carbon overlayer at the surface and (iii) reduction of calcined catalysts leads to increasing C sp³ hybridisations.     

How to select a small set of diverse solutions to mixed integer programming problems

Given an oracle that generates a large number of solutions to mixed integer programs, we present exact and heuristic approaches to select a small subset of solutions that maximizes solution diversity. We obtain good results on binary variables, but report scaling problems when considering general integer and continuous variables.     

两类赋予w~＊-可分对偶的空间的BCP

在对偶w~＊-可分的情况下,证明了两类Banach空间具有球覆盖性质,即：它们是1）光滑空间;2）具有MIP的空间.     

Electro-optical and dielectric study of multi-walled carbon nanotube doped polymer dispersed liquid crystal films

The self-organising property of nematic liquid crystals (LCs) was used to align multi-walled carbon nanotubes (MWCNT) dispersed in them. MWCNT not only well integrate in the matrix but also, even at very low concentration, have a detectable effect on the LC properties that can be very attractive for display applications. In the present work, MWCNT were doped (0–0.5% wt/wt) in two different types of LCs. These MWCNT doped polymer dispersed LC (CPDLC) films were studied comprehensively using fundamental techniques. Polarising optical microscope (POM) and scanning electron microscope (SEM) techniques used for morphological study reveal that the LC droplet size remains unchanged with increase in MWCNT concentration. The electro-optical (EO) study performed by increasing voltage in steps of 10 V up to 100 V at an optimised frequency of 200 Hz and at temperature 25°C shows that the low MWCNT concentration films show good optical response than the higher one. The dielectric behaviour of CPDLC films in the frequency range 20 Hz to 20 MHz was investigated using precision impedance analyser. The obtained data were modelled with Debye and Cole-Cole methods to calculate relaxation time and distribution parameter (α). The zero value of α indicates Debye type relaxation processes.