JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2014
·Vol. 117
·期 2
·603-610
·
IF 2.206
Liu Jialin,Li Jingrui,Fan Mengjin,Zhang Junying,Cheng Jue
Aromatic amine curing agent with flexible unit in backbone, 1,4-bis (4-diaminobenzene-1-oxygen) n -butane (DDBE), was synthesized, and the structure was confirmed by FT-IR and 1 H NMR. The curing kinetics of tetraglycidyl methylene dianiline (TGDDM, or AG80) using DDBE and 4,4′-bis-(diaminodiphenyl) methane (DDM) as curing agents, respectively, were comparatively studied by non-isothermal DSC with a model-fitting Málek approach and a model-free advanced isoconversional method of Vyazovkin. The dynamic mechanical properties and thermal stabilities of the cured materials were investigated by DMTA and TG, respectively. The results showed that the activation energy of AG80/DDBE system was slightly higher than that of AG80/DDM system. Šesták-Berggren model can generally simulate well the reaction rates of these two systems. DMTA measurements showed that the storage modulus of cured AG80/DDBE is similar to that of cured AG80/DDM at the temperature below glass transition temperature ( T
g ) and lower than that of cured AG80/DDM at the temperature above glass transition temperature, while T
g of cured AG80/DDBE is lower than that of cured AG80/DDM. TG showed that the thermal stabilities of these two cured systems are similar.
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MICROCHIMICA ACTA
·
2014
·Vol. 181
·期 11
·1223-1230
·
IF 3.719
Wang Ke,Wei Xiuhua,Tu Yifeng
This paper reports on the synthesis of AuAg and PtAg alloy nanoclusters (NCs) and their enhancement effect on the electrochemiluminescence (ECL) of luminol. The conditions of synthesis were optimized, and the structure and properties of the NCs were characterized by X-ray diffraction, transmission electron microscopy, electrochemistry, and optical spectroscopy. The NCs are found to intensify (by up to 20 times) the ECL of luminol in solution of pH 8.5. This finding can largely extend the useful pH range of the ECL of luminol. The enhanced ECL is strongly affected by oxygen and hydrogen peroxide, and the mechanism of enhancement is attributed to the accelerated production of reactive oxygen species. The enhanced ECL is also affected by phenolic artificial estrogens, and this was used for their determination with detection limits as low as 700 pg L− 1 (with AuAg) and 1.6 ng L− 1 (with PtAg). The method was applied to the determination of such estrogens in egg samples using diethylstilbestrol as a reference substance.
The alloy nanoclusters (AuAg/PtAg) have been synthesized. They enhance the electrochemiluminescence of luminal for about 20 times in pH 8.5 solution. It extended the practicable pH range of ECL and can be employed for detecting the oxygen matters and other related trace compounds.
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RESEARCH ON CHEMICAL INTERMEDIATES
·
2014
·Vol. 41
·期 8
·5059-5069
·
IF 1.54
Zhang Datong,Ma Yuntong,An Ruibing
A rhodamine-based chemosensor for naked-eye detection of Cu 2+ has been designed and synthesized, which exhibited excellent selectivity and high sensitivity for Cu 2+ in CH 3 CN and CH 3 CN/H 2 O mixed solutions. When Cu 2+ was added to the solution of sensor 1 , a dramatic color change from colorless to bluish violet was observed, while the cations K + , Ca 2+ , Na + , Hg 2+ , Zn 2+ , Co 2+ , Ni 2+ , Fe 3+ , Al 3+ , Pb 2+ , Ag + , and Cd 2+ did not interfere with the recognition process for Cu 2+ . The pH effect investigations indicated that it can be applied to analysis of samples over a wide pH range.
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JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2014
·Vol. 18
·期 7
·2013-2018
·
IF 2.234
Zheng Jinyun,Li Xiao,Yu Yujian,Zhen Xiaomin,Song Yanyao,Feng Xiangming,Zhao Yufen
The cross-linking gel copolymer electrolytes containing alkyl acrylates, triethylene glycol dimethacrylate, and liquid electrolyte were prepared by in situ thermal polymerization. The gel polymer electrolytes containing 15 wt% polymer content and 85 wt% liquid electrolyte content with sufficient mechanical strength showed the high ionic conductivity around 5 × 10 −3 Scm −1 at room temperature. The gel electrolytes containing different polymer matrices were prepared, and their physical observation and conductivity were discussed carefully. The cross-linking copolymer gel electrolytes of alkyl acrylates with other monomers were designed and synthesized. The results showed that copolymerization can improve the mechanical properties and ionic conductivities of the gel electrolytes. The polymer matrices of gels had excellent thermal stability and electrochemical stability. The scanning electron microscope analysis showed the gel electrolyte was the homogeneous structure, and the cross-linking polymer host was the porous three-dimensional network structure, which demonstrated the high conductivity of the gel electrolytes. The gel polymer Li-ion battery was prepared by this in situ thermal polymerization. The cell exhibited high charge-discharge efficiency at 0.1 C. The results of LiFePO4-PEA-Li cell and graphite-PEA-Li cell showed that gel polymer electrolytes have good compatibility with the battery electrodes materials.
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JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2013
·Vol. 18
·期 3
·621-628
·
IF 2.279
Ma Xinying,Chao Mingyong
A novel poly(methylene blue)/graphene composite glassy carbon electrode was fabricated and the electrochemical behavior of maltol at the modified electrode was studied by cyclic voltammetry. In phosphate-buffered solution, the modified electrode exhibited excellent electrocatalytic activity towards the electrochemical oxidation of maltol. Under optimized conditions, the oxidation peak current showed a linear relationship with the concentrations of maltol in the ranges of 8.00 × 10 −7 to 4.00 × 10 −5 and 4.00 × 10 −5 to 5.40 × 10 −4 mol L −1 , with a detection limit of 6.50 × 10 −8 mol L −1 . The performance of the developed method was validated in terms of linearity ( r = 0.9981 and 0.9955), recovery (97.0−99.3 %), reproducibility (relative standard deviations ≤ 3.1 %, n = 6), and robustness. The method shows excellent sensitivity, selectivity, and reproducibility and has been successfully applied to analyzing maltol in a wide variety of food products.
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MICROCHIMICA ACTA
·
2013
·Vol. 181
·期 1
·105-110
·
IF 3.434
Wang Xiaokun,Chen Ling,Chen Lingxin
We have developed a method for the colorimetric determination of copper ions (Cu 2+ ) that is based on the use of silver-coated gold nanorods (Au@Ag NRs). Its outstanding selectivity and sensitivity result from the catalytic leaching process that occurs between Cu 2+ , thiosulfate (S 2 O 3
2− ), and the surface of the Au@Ag NRs. The intrinsic color of the Au@Ag NRs changes from bright red to bluish green with decreasing thickness of the silver coating. The addition of Cu 2+ accelerates the leaching of silver from the shell caused in the presence of S 2 O 3
2− . This result in a decrease in the thickness of the silver shell which is accompanied a change in color and absorption spectra of the colloidal solution. The shifts in the absorption maxima are linearly related to the concentrations of Cu 2+ over the 3–1,000 nM concentration range ( R = 0.996). The method is cost effective and was applied to the determination of Cu 2+ in real water samples.
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Chemistry Central Journal
·
2013
·Vol. 7
·期 1
·1-5
·
IF 1.312
Liu Run-Qiang,Bai Lian-yang,Zhang Yi-Jun,Zhang Yu-Ping
Background At present, the study on the homogeneous-phase derivatization of cellulose in ionic liquid is mainly focused on its acetylation. To the best of our knowledge, there has been no such report on the preparation of cellulose-tris(3,5-dimethylphenylcarbamate) (CDMPC) with ionic liquid 1-allyl-3-methyl-imidazolium chloride (AmimCl) so far.Results With ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) as a reaction solvent, cellulose-tris(3,5-dimethylphenylcarbamate) (CDMPC) was synthesized by the reaction of 3,5-dimethylphenyl isocyanate and soluble microcrystalline cellulose in a homogeneous phase. The synthesized CDMPC was then coated onto the surfaces of aminopropyl silica gel to prepare a chiral stationary phase (CSP). The prepared CSP was successfully used in chiral separation of seven racemic pesticides by high performance liquid chromatography (HPLC). Good chiral separation was obtained using n-hexane and different modifiers as the mobile phases under the optimal percentage and column temperature, with the resolution of metalaxyl, diniconazole, flutriafol, paclobutrazol, hexaconazole, myclobutanil and hexythiazox of 1.73, 1.56, 1.26, 1.00, 1.18, 1.14 and 1.51, respectively. The experimental results suggested it was a good choice using a green solvent of AmimCl for cellulose functionalization.Conclusion CDMPC was successfully synthesized as the chiral selector by reacting 3, 5-dimethylphenyl isocyanate with dissolved microcrystalline cellulose in a green ionic liquid of AmimCl.
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高影响因子
Chemistry Central Journal
·
2013
·Vol. 7
·期 1
·1-9
·
IF 1.312
Chen Feng,Li Hai-long,Li Yong-Hui,Tan Yin-Feng,Zhang Jun-Qing
Background The SuoQuan formulae containing Fructus Alpiniae Oxyphyllae has been used to combat the urinary incontinence symptoms including frequency, urgency and nocturia for hundreds of years in China. However, the chemical information was not well characterized. The quality control marker constituent only focused on one single compound in the current Chinese Pharmacopeia. Hence it is prudent to identify and quantify the main constituents in this herbal product. This study aimed to analyze the main constituents using ultra-fast performance liquid chromatography coupled to tandem mass spectrometry (UFLC-MS/MS). Results Fourteen phytochemicals originated from five chemical classes constituents were identified by comparing the molecular mass, fragmentation pattern and retention time with those of the reference standards. A newly developed UFLC-MS/MS was validated demonstrating that the new assay was valid, reproducible and reliable. This method was successfully applied to simultaneously quantify the fourteen phytochemicals. Notably, the content of these constituents showed significant differences in three pharmaceutical preparations. The major constituent originated from each of chemical class was isolinderalactone, norisoboldine, nootkatone, yakuchinone A and apigenin-4’,7-dimethylther, respectively. The variation among these compounds was more than 1000 times. Furthermore, the significant content variation between the two different Suoquan pills was also observed. Conclusion The proposed method is sensitive and reliable; hence it can be used to analyze a variety of SuoQuan formulae products produced by different pharmaceutical manufacturers.
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Nano Research
·
2015
·Vol. 8
·期 8
·2548-2561
·
IF 7.01
Wang Jiahong,Huang Hao,Zhang Daquan,Chen Ming,Zhang Yafang,Yu Xuefeng,Zhou Li,Wang Ququan
The nanoscale core/shell heterostructure is a particularly efficient motif to combine the promising properties of plasmonic materials and rare-earth compounds; however, there remain significant challenges in the synthetic control due to the large interfacial energy between these two intrinsically unmatched materials. Herein, we report a synthetic route to grow rare-earth-vanadate shells on gold nanorod (AuNR) cores. After modifying the AuNR surface with oleate through a surfactant exchange, well-packaged rare-earth oxide (e.g., Gd 2 O 3 :Eu) shells are grown on AuNRs as a result of the multiple roles of oleate. Furthermore, the composition of the shell has been altered from oxide to vanadate (GdVO 4 :Eu) using an anion exchange method. Owing to the carefully designed strategy, the AuNR cores maintain the morphology during the synthesis process; thus, the final Au/GdVO 4 :Eu core/shell NRs exhibit strong absorption bands and high photothermal efficiency. In addition, the Au/GdVO 4 :Eu NRs exhibit bright Eu 3+ fluorescence with quantum yield as high as ~17%; bright Sm 3+ and Dy 3+ fluorescence can also be obtained by changing the lanthanide doping in the oxide formation. Owing to the attractive integration of the plasmonic and fluorescence properties, such core/shell heterostructures will find particular applications in a wide array of areas, from biomedicine to energy.
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MICROCHIMICA ACTA
·
2015
·Vol. 182
·期 13
·2277-2283
·
IF 3.741
Wang Yong,Qu Jianhang,Li Shufang,Dong Ying,Qu Jianying
We describe an electrochemical sensor for simultaneous determination of hydroquinone (HQ) and catechol (CC). A glassy carbon electrode (GCE) was modified with gold nanoparticles, L-cysteine, and ZnS/NiS@ZnS quantum dots using a layer-by-layer technique. The materials were characterized by X-ray diffractometry, field emission scanning electron microscopy, and electrochemical impedance and Fourier transform infrared spectroscopy. Cyclic voltammetry and differential pulse voltammetry revealed this modified GCE to represent a highly sensitive sensor for the simultaneous determination of HQ and CC. The anodic peak current for HQ at a working voltage of 80 mV (vs. Ag/AgCl) is related to its concentration in the 0.1 to 300 μM range (even in the presence of 0.1 mM of CC). The anodic peak current for CC at a working voltage of 184 mV is related to its concentration in the 0.5 to 400 μM range (even in the presence of 0.1 mM of HQ). The detection limits (at an S/N ratio of 3) are 24 and 71 nM for HQ and CC, respectively. The modified GCE was successfully applied to the determination of HQ and CC in aqueous solutions and gave satisfactory results.
A glassy carbon electrode was modified with gold nanoparticles, ZnS/NiS@ZnS quantum dots and L-cysteine and used for simultaneous determination of hydroquinone and catechol.
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WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY
·
2013
·Vol. 30
·期 1
·245-252
·
IF 1.262
Wang Hualei,Li Guinan,Li Mingyang,Wei Dongzhi,Wang Xuedong
In this study, a novel nitrilase gene from Rhodobacter sphaeroides was cloned and overexpressed in Escherichia coli . The open reading frame of the nitrilase gene includes 969 base pairs, which encodes a putative polypeptide of 322 amino acid residues. The molecular weight of the purified native nitrilase was about 560 kDa determined by size exclusion chromatography. This nitrilase showed one single band on SDS-PAGE with a molecular weight of 40 kDa. This suggested that the native nitrilase consisted of 14 subunits with identical size. The optimal pH and temperature of the purified enzyme were 7.0 and 40 °C, respectively. The kinetic parameters V
max and K
m toward 3-cyanopyridine were 77.5 μmol min −1 mg −1 and 73.1 mmol/l, respectively. The enzyme can easily convert aliphatic nitrile and aromatic nitriles to their corresponding acids. Furthermore, this enzyme demonstrated regioselectivity in hydrolysis of aliphatic dinitriles. This specific characteristic makes this nitrilase have a great potential for commercial production of various cyanocarboxylic acids by hydrolyzing readily available dinitriles.
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CHINESE SCIENCE BULLETIN
·
2013
·Vol. 58
·期 22
·2728-2732
·
IF 1.319
Chen DiDi,Feng Xiao,Gu ShangZhi,Tong Bin,Shi JianBing,Zhi JunGe,Dong YuPing
Tetraphenylethylene (TPE) derivatives have been proved to be typical aggregation-induced emission (AIE) luminogens when they were aggregated in the free three-dimensional space. In order to reveal the effect of the dimensional degree on AIE property of TPEs, we utilized tetra(4-hydroxyphenyl)ethylene (TPE-4OH) and 1,4-benzenediamine diazonium salt (BD) to fabricate the ultra-thin films (TPE-4OH/BD LBL SA film) through layer-by-layer self-assembled technique. The interaction between TPE-4OH and BD in the films was converted from electrostatic force and hydrogen-bond to covalent bonds through photodecomposition of diazonium groups under UV irradiation. Fluorescence emission spectroscopy, UV-Vis absorption spectroscopy and atomic force microscope were carried out to evaluate the relationship between bilayer number and photoluminescence of the TPE-based self-assembled films. The experimental results showed that the TPE-based film with three bilayers only displayed AIE character, whereas the fluorescence of the film became randomly changed if the bilayer number was above three. It is supposed that the fluorescence property of the TPE-4OH/BD LBL SA film with limited molecular length in z -axis and infinite aggregation space in x - and y -axis is dominated by two competitive effects, one is the partial restriction of intramolecular rotation through short intermolecular interactions in cross-linked structure of TPE-4OH/BD, and the other is deactivation of its excited state through unrestricted intramolecular rotations or π-π interactions.
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