Chemical Research in Chinese Universities

Chemical Research in Chinese Universities Vol.35 No.6 December 2019

2019, 35(6): 0-0.

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Large Scale Synthesis of Transition Metal Single Atom Catalysts by a Universal Ligand Mediated Method

HAN Buxing

2019, 35(6): 951-952. doi:10.1007/s40242-019-0046-x

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Series of transition metal single atom catalysts containing Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Pt or combinations thereof were synthesized in a large scale by a universal ligand mediated method. The as-synthesized single atom catalysts exhibited excellent electrochemical CO₂ reduction activity.

Controllable Synthesis of Mesoporous Multipods for Enhanced Nano-bio Interactions

SHI Jianlin

2019, 35(6): 953-954. doi:10.1007/s40242-019-9018-4

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Precise manipulation of surface topology has been being a great challenge for the fabrication of functional nanomaterials. Very recently Zhao and coworkers developed a surface-kinetic mediated multi-site nucleation strategy to precisely control the nucleation number of periodic mesoporous organosilicas(PMOs) on the surface of magnetic nano-spheres. The as-prepared mesoporous multipods(especially the Tribulus-like tetra-pods mesoporous nanoparticles) present high bacteria adhesion efficiency through multivalent interactions, which are expected to be the promising candidates for future antibacterial applications. This work has been published online in the Nature Communications in September 26, 2019.

Crystalline, Few-layer 2D Materials via Surfactant-monolayer-assisted Interfacial Synthesis

HU Yiming, JIN Yinghua, ZHANG Wei

2019, 35(6): 955-956. doi:10.1007/s40242-019-1014-1

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Prof. FENG Xinliang and coworkers from Dresden University of Technology reported surfactant-monolayer-assisted interfacial synthesis(SMAIS) as a general strategy for the controlled synthesis of few-layer 2D polymers to realize high crystallinity with large domain. The two-dimensional polyamide(Nature Chemistry, doi.org/10.1038/s41557-019-0327-5) and quasi-two-dimensional polyaniline(Nature Communication, doi.org/10.1038/s41467-019-11921-3) thin films were successfully obtained with the help of surfactants and fully characterized by optical microscopy, transmission electron microscopy, electron diffraction and atomic force microscopy.

Preparation and Pseudo-capacitance Performance of NiCo₂O₄ Nanosheets

ZHOU Qi, JIAO Sunzhi, ZHENG Bin, LI Zhiyang

2019, 35(6): 957-961. doi:10.1007/s40242-019-9172-8

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Ternary nickel cobaltite(NiCo₂O₄), as a promising electrode material for supercapacitors, has attracted increasing attention for its excellent electrochemical properties. In this study, novel NiCo₂O₄ nanosheets were rationally designed and prepared using dealloying process, followed by an oxidation treatment. The as-prepared sample was characterized by microstructural and electrochemical techniques in view of its possible application in supercapacitors. The as-prepared sample exhibited high specific capacitance and excellent durability. The specific capacitance reached 663 F/g at 1 A/g and the rate capacitance high up to 73.6% when the current density increased from 1 A/g to 20 A/g. After 5000 cycles of galvanostatic charge-discharge durability test at 4 A/g, the capacity retention rate was 82.1%. The results indicate that versatile dealloying can be used to prepare robust electrode for supercapacitor application.

Measurement of Free and Glucuronidated Cardamonin in Rat Plasma and Bile Using UPLC-MS/MS and Its Application to a Pharmacokinetic and Bile Excretion Study

WU Yi, JING Runan, JIA Guihua, WANG Yixiao, YU Tianmiao, ZHANG Weidong

2019, 35(6): 962-966. doi:10.1007/s40242-019-9275-2

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A rapid and accurate ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry(UPLC-MS/MS) method was established and validated for the measurement of two forms of cardamonin, i.e., free and glucuronidated, in the plasma and bile of rats. Cardamonin and an internal standard (1,8-dihydroxyanthraquinone) were extracted from plasma and bile with ethyl ether via liquid-liquid extraction. The analytes in the extracts were separated by an Agilent Zorbax Stable Bond-C₁₈ column(2.1 mm×50 mm, 1.8 μm) under isocratic elution conditions[acetonitrile(A) and 0.1% ammonium formate in water(B), 40:60(volume ratio)] with a flow rate of 0.4 mL/min, and mass spectrometry in negative ion MRM mode was implemented for analysis. Good linearity over the wide ranges of 0.01-5 μg/mL for plasma and 0.025-10 μg/mL for bile samples was acquired. Method validation was performed according to the FDA guidelines for bioanalytical methods.

A Sensitive Fluorescent Turn-on Probe NapP-deap Based on Naphthalimide Derivative to Detect Hg(II) Ions in HEPES Buffer Solution and Living Cells

WANG Shuxin, CAO Jian, CHENG Yuxiao, LU Chenhong

2019, 35(6): 967-971. doi:10.1007/s40242-019-9246-7

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A highly sensitive fluorescent "turn-on" probe NapP-deap based on naphthalimide derivative was deve-loped that bound Hg²⁺ ions rapidly in the N-2-hydroxyethylpiperazine-N-ethane-sulphonic acid(HEPES) buffer solution via photo-induced electron transfer(PET) being inhibited mechanism. The titration experiment displayed that the emission intensity of NapP-deap at 540 nm was almost linearly increased by about 3-fold. The Job's plot showed a stoichiometry factor of 1:1 of the ligand-to-metal ratio. The detection limit of fluorescent probe was calculated to be 6.2×10^-9 mol/L. ¹H NMR studies could confirm that one Hg²⁺ ion was bound by the N atoms(a, b) of piperazine or the N atom(c) of pyridine. The fluorescent probe could be used for the detection of Hg²⁺ ions in living cells.

A Smartphone-assisted Paper-based Analytical Device for Fluorescence Assay of Hg²⁺

YE Jiawen, GENG Yijia, CAO Fanghao, SUN Dan, XU Shuping, CHANG Jingjing, XU Weiqing, CHEN Qidan

2019, 35(6): 972-977. doi:10.1007/s40242-019-9234-y

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Rapid, efficiency and portable detection systems in low-resource settings with limited laboratory equipment and technical expertise are urgently needed. Herein, an integrated platform composed of a paper-based analytical device and a smartphone detection system for Hg²⁺ onsite testing was developed. Nitrogen-doped carbon dots(N-CDs) were synthesized by a simple hydrothermal method using citric acid as the carbon source and ethanediamine as the nitrogen source, which gave out bright blue fluorescence under the excitation at 350 nm UV light and the absolute fluorescence quantum yield was 17.1%. The fluorescence of the prepared N-CDs can be effectively quenched by Hg²⁺. In addition, an external attachment of smartphone for illumination and external light interference was designed to trace the fluorescence signals, and a software application of Android system with simple operation program was developed to perform snapshot and image processing. The smartphone-assisted detection system was combined with the N-CDs decorated paper chip to achieve the sensitive detection of Hg²⁺ in water samples. This integrated method for reliable sensing of Hg²⁺ shows a good linear detection range of 10-800 μmol/L(R²=0.9595) with detection limit of 1.07×10^-8 mol/L.

Enantioseparation by HPLC Using an Inorganic Chiral Mesoporous Silica with Highly-ordered Structure

PENG Bo, FU Shiguo, LI Yanxia, ZHANG Junhui, XIE Shengming, LI Li, LYU Yun, DUAN Aihong, CHEN Xuexian, YUAN Liming

2019, 35(6): 978-982. doi:10.1007/s40242-019-9162-x

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Highly-ordered inorganic chiral mesoporous silica(HOCMS) has attracted substantial interest in recent decades. High performance liquid chromatography(HPLC) is the most important approach for the separation of enantiomers and herein reported an HPLC chiral stationary phase composed of HOCMS. The column was fabricated by conventional high pressure slurry packing. Eighteen racemates, including alcohols, ketones, amines, aldehydes and organic acids, were resolved on the column. Good chiral separations of hydrobenzoin, metoprolol, propranolol hydrochloride, 4-methyl-2-pentanol, omeprazole, 2,2'-furoin and ketoprofen were obtained. The relative standard deviations for five replicate separations of racemates were 0.1%-0.16% for retention time and 1.73%-2.64% for peak areas. The results suggest that HOCMS is a promising candidate for preparation of chiral stationary phases for HPLC.

Supplemental Feeding of Laying Hens with Wood Vinegar to Decrease the Ratio of n-6 to n-3 Fatty Acids in Eggs

ZHAO Nan, XIN Hua, LI Zhanchao, WANG Ziming, ZHANG Lening

2019, 35(6): 983-989. doi:10.1007/s40242-019-9140-3

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A balanced ratio of fatty acids n-6 to n-3 in chicken eggs is important for health and to help prevent and manage obesity and other diseases. Traditionally, fish oil or flax seed has been utilized as feed additives to decrease the ratio of n-6 to n-3(n-6:n-3) fatty acids in eggs. The hull of spina date seed(HSDS) is a common agricultural waste product in China, from which wood vinegar(HSDSWV) may be derived. This study evaluated HSDSWV as a supplement in hen feeds to improve the quality of eggs and decrease the ratio of fatty acids n-6:n-3. HSDSWV was obtained via carbonization, and refined. Six concentrations(nil to 0.5%) of HSDSWV were prepared and fed to 6 hen groups, respectively, for 50 d. The fatty acids of the hen's egg yolks were analyzed by gas chromatography/electron ionization-mass spectrometry(GC/EI-MS) in the selected ion monitoring(SIM) mode. The 0.2% HSDSWV resulted in the best egg yolk quality, with a lower percentage of linoleic acid(C18:2n6) and higher percentages of cis-5,8,11,14,17-eicosapentaenoic acid(C20:5n3) and cis-4,7,10,13,16,19-docosahexaenoic acid(C22:6n3), and thus a lower n-6:n-3 ratio compared with the other HSDSWV concentrations. In addition, the eggs contained higher levels of yolk fat and egg yolk than the controls did. In conclusion, to modify the fatty acid composition of hens' eggs and obtain a balanced ratio of n-6:n-3, 0.2% HSDSWV may be considered suitable as a dietary supplement in hens' feed.

Fluorescent Turn-on Probe Based on Napthalimide Fused Triphenylamine Unit for Quickly Detecting Thiophenol in Aqueous Solution

SUN Jiaojiao, CAO Jian, CHENG Hailong, WANG Jincheng, WANG Shuxin

2019, 35(6): 990-996. doi:10.1007/s40242-019-9033-5

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A novel molecular probe system(NapTpa-dnbs) was prepared based on the chromophore napthalimide fused triphenylamine unit. NapTpa-dnbs was tuned to absorb a large fraction of UV and near-infrared radiation. The turn-on fluorescent response of NapTpa-dnbs to thiophenol caused an increased fluorescent emission by a factor of 11.5 at 597 nm in a PBS buffer solution. The photoinduced electron transform(PET) process of the probe became less feasible with the addition of thiophenol than that of the free probe. NapTpa-dnbs demonstrated high selective and sensitive detection toward thiophenol with respect to other competitive amine acids. The detection limit was determined to be 2.03×10^-7 mol/L thiophenol. The sensing process is rapid(3 min). NapTpa-dnbs can accurately detect the thiophenol with a qualified recovery in real water samples. NapTpa-dnbs on test strips can detect the thiophenol vapour in the atmosphere.

Selective N-Alkylation of 2-Amino-4H-chromene-3-carbonitrile Derivatives with Alcohols Catalyzed by AlCl₃ Under the Assistance of CH₃COOH

ZHAO Bing, HE Yuqian, KAN Wei, KONG Fengqiao, WANG Liyan, SONG Bo, WANG Wenbo, YIN Guangming, WANG Jianxin

2019, 35(6): 997-1001. doi:10.1007/s40242-019-9248-5

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A highly efficient and selective N-alkylation reaction of 2-amino-4H-chromene-3-carbonitrile derivatives using various alcohols as alkylation agent were developed in the presence of AlCl₃ as a catalyst as well as CH₃COOH as an additive, in which the cyano group kept inert and the amino group was alkylated in high yields. All the target products were characterized and determined by infrared(IR), ¹H NMR, ¹³C NMR, and HRMS. And the X-ray structure of product 3ab was obtained. A bimolecular reaction mechanism catalyzed by AlCl₃ was proposed under the assistance of CH₃COOH.

K₃PO₄-promoted Cyclopropanation of Electron-deficient Alkenes with 2-Bromo-1,3-propanedione Compounds

CHEN Zhanguo, WEN Ting, HOU Dan

2019, 35(6): 1002-1007. doi:10.1007/s40242-019-9137-y

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An easy and efficient method for the synthesis of multisubstituted cyclopropane derivatives from electron-deficicent alkenes with 2-bromo-1,3-propanedione compounds was described. For this method, ethyl α-cyanocinnamate derivatives 1 and β,β-dicyanostyrene derivatives 4 can all smoothly react with 2-bromo-1,3-propanedione compounds 2 to afford the corresponding multisubstituted cyclopropane derivatives 3 and 5 in good to excellent yields(up to 100%) promoted by anhydrous K₃PO₄ in DMF at room temperature, respectively. A possible mechanism of this reaction was proposed. Structures of all the products were confirmed by ¹H NMR, ¹³C NMR and HRMS.

Synthesis and Herbicidal Activity of Novel β-Methoxyacrylate Derivatives Containing a Substituted Phenylpyridine Moiety

CAO Yangyang, CAI Zengfei, ZHANG Wenliang, DU Xiaohua

2019, 35(6): 1008-1011. doi:10.1007/s40242-019-9128-z

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In this paper, a series of new β-methoxyacrylate derivatives containing a substituted phenylpyridine moiety was synthesized and bioassayed. The structures of all compounds were confirmed by nuclear magnetic resonance(NMR) and high-resolution mass spectrometry(HRMS). Preliminary bioassays demonstrated that compound 8d showed more than 95% inhibition against Brassica juncea and Chenopodium serotinum at 37.5 g a.i./10⁴ m², when compared with the positive control halauxifen-methyl at 150 g a.i./10⁴ m². The present work demonstrated that compound 8d exhibited the more promising herbicidal activity and may serve as a new herbicidal agent for herbicide.

Hydrogen Production by Chemical Looping Gasification of Corn Stalk Driven by a tert-Butanol Solution

QIN Wu, CHEN Shubo, ZHU Jinqi, ZHANG Maodong, XIAO Xianbin

2019, 35(6): 1012-1017. doi:10.1007/s40242-019-9225-z

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The purpose of this work is to convert organic wastewater into oxidants(H₂O and CO₂) to promote biomass gasification during the chemical looping process to achieve high-H₂/CO-ratio syngas. A tert-butanol solution was selected as the model organic wastewater to generate enough H₂O and CO₂ to promote corn stalk chemical looping gasification(CLG). A series of CLG experiments was conducted at 850℃ under various degrees of oxygen excess(Ω). An Ω of approximately 0.9 led to the highest hydrogen yield and fixed carbon conversion compared with the other cases. Chemometrics and thermodynamic analysis further validated the possibility of corn stalk CLG using a tert-butanol solution. The results show that CLG of biomass-organic wastewater can both treat organic waste and promote chemical looping processes.

Solid-liquid Phase Equilibria in the Process of Producing Lithium Hydroxide from Lithium Sulfate

GUO Jian, WU Peng, LI Yaoyao, ZHANG Min, LI Wenxuan, ZHOU Huan

2019, 35(6): 1018-1023. doi:10.1007/s40242-019-9197-z

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The solid-liquid phase equilibria in the process of producing lithium hydroxide from lithium sulfate at 283.15, 298.15 and 323.15 K were studied via the isothermal solubility equilibrium method, and the solid species, phase diagrams, solution densities and pH were determined. The results show that four solid species of Na₂SO₄·10H₂O, Na₂SO₄·2.5H₂O, Na₂SO₄ and LiOH·H₂O occurred in the system, among them, Na₂SO₄·2.5H₂O was a new solid species not reported in the open literature, which was determined via chemical analysis, Karl Fischer water titration, X-ray diffraction(XRD), thermogravimetic analysis(TG) and differential scanning calorimetry(DSC) testing. Based on the SLE data, one systemic process to produce LiOH·H₂O from Li₂SO₄·H₂O was proposed including two crystallization steps at lower and higher temperatures.

Effect of Preparation Method on the Structural Characteristics of NiO-ZrO₂ Oxygen Carriers for Chemical-looping Combustion

LIU Yike, LONG Yanhui, TANG Yaqin, GU Zhenhua, LI Kongzhai

2019, 35(6): 1024-1031. doi:10.1007/s40242-019-9189-z

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Chemical-looping combustion(CLC) offers an effective approach for power generation and CO₂ capture. In this work, an NiO-ZrO₂ oxygen carrier prepared by three methods was subjected to an optimal reaction temperature test, an optimal flow test and a cyclic redox reaction test to explore the most suitable reaction conditions. Through comparative analysis, it is noted that the coprecipitation method is not suitable for the preparation of this NiO-ZrO₂ oxygen carrier, while the oxygen carrier prepared by the mechanical mixing method and solution combustion method obtained a higher CH₄ conversion rate and CO₂ selectivity. In addition, these two oxygen carriers also showed high stability during successive CLC testing. Therefore, both the mechanical mixing method and the solution combustion method can be used to prepare NiO-ZrO₂ oxygen carriers.

Novel Small Four-armed Molecules with Triphenylamine-bridged Structure for Organic Solar Cells Featuring High Open-circuit Voltage

HE Xiaodong, ZHU Jianling, YIN Lunxiang, XIE Bao, LI Kechang, LI Yanqin

2019, 35(6): 1032-1039. doi:10.1007/s40242-019-9179-1

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In view of few attention on star-shaped molecules containing triphenylamine(TPA) unit as π-linker, a series of small four-armed molecules, consisting of octyloxy-substituted 2,1,3-benzothiadiazole(DOBT) or 4-octyl-2-thienyl functionalized DOBT as the core, TPA as π-bridge and 4-methylphenyl or 4-methoxyphenyl groups as terminal units, was designed and synthesized. The effects of π-bridges and substitute groups on molecular photoelectric performance and photovoltaic performance were fully explored. With the help of the additional thiophene-linkers incorporation, 3-octylthienyl substituted molecule with end-capping 4-methylphenyl(T-BTTPAM) and 3-octylthienyl substituted molecule with end-capping 4-methoxyphenyl(T-BTTPAOM) showed stronger and broader absorption, as well as higher charge mobilities compared to the molecules without thiophene-linkers(BTTPAM and BTTPAOM). Additionally, changing substitute groups from methyl to methoxy helped BTTPAOM and T-BTTPAOM achieve better absorption properties than BTTPAM and T-BTTPAM, respectively. When paired with PC₆₁BM as the electron acceptor to fabricate solution-processed photovoltaic devices, the four materials gave high open-circuit voltage(V_oc) values over 0.90 V. These results demonstrate that our materials are promising candidates as donor materials for organic solar cells(OSCs), and further device optimization is in progress in our laboratory.

Crystal Structures and Electrochemical Properties of R_1.5Ca_1.5MgNi₁₄(R=Nd, Gd and Er) Hydrogen Storage Alloys

ZANG Jiahe, ZHANG Qing'an, SUN Dalin

2019, 35(6): 1040-1045. doi:10.1007/s40242-019-9173-7

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Ca₃MgNi₁₄, Nd_1.5Ca_1.5MgNi₁₄, Gd_1.5Ca_1.5MgNi₁₄ and Er_1.5Ca_1.5MgNi₁₄ alloys were prepared by high frequency induction melting and sintering. Characterization and analysis were performed by X-ray diffraction/Rietveld full-spectrum fitting, gaseous P-C-T hydrogen storage test and electrochemical properties tests. It can be found that all alloys consist of Gd₂Co₇-type 3R phase and Ce₂Ni₇-type 2H phase. Although the hydrogen storage capacities of Nd_1.5Ca_1.5MgNi₁₄, Gd_1.5Ca_1.5MgNi₁₄ and Er_1.5Ca_1.5MgNi₁₄ decrease to some extent compared to that of Ca₃MgNi₁₄, their equilibrium pressures for absorption and desorption increase markedly. Moreover, R_1.5Ca_1.5MgNi₁₄ alloys have better cycling stabilities and high-rate discharge(HRD) properties as compared to Ca₃MgNi₁₄. The hydrogen diffusion in alloy electrodes is the main factor to influence the HRD performance.

Study of the Synergistic Effect Between Corrosion Inhibitors by Using Fractional Free Volume

LU Yuan, ZHANG Chen, WANG Wei, ZHAO Jingmao

2019, 35(6): 1046-1051. doi:10.1007/s40242-019-9171-9

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The fractional free volumes(FFVs) of the adsorption films formed with different ratios of dipropargyl methoxythiourea imidazoline(DPFTAI) and pyridine quaternary ammonium salt(16BD) were calculated by simulation to determine their synergistic corrosion inhibition effect. The results suggest that the composite corrosion inhibitor at the molar ratio between DPFTAI and 16BD of 4:1 gives the best corrosion inhibition effect. This simulation method to predict the synergistic effect between corrosion inhibitors was further validated by mass loss and electrochemical experiments. This finding delivers valuable understandings of inhibition mechanism of corrosion inhibitors.

Improved Electrochemical Kinetic Performances of La-Mg-Ni-based Hydrogen Storage Alloy Modified by Ni-Polypyrrole Complex Surface Treatment

YANG Shuqin, WANG Yunchai, LI Yuan, SONG Laizhou

2019, 35(6): 1052-1057. doi:10.1007/s40242-019-9169-3

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In order to improve the electrochemical kinetic performances of La-Mg-Ni-based alloy, complex surface modification of Ni with excellent catalytic activity and conducting polymer polypyrrole(PPy) was performed via electroless plating method. FESEM images revealed that the complex Ni-PPy treatment resulted in more micropores at the alloy surface, with Ni particles and cotton fiber-shape PPy microspheres attached. Both the larger surface area induced by the micropore and the higher catalytic activity and conductivity on account of the dispersed Ni particles/PPy microspheres promoted the electrode reaction, thereby increasing the discharge capacity of the modified alloy electrode. Electrochemical impedance spectroscopy(EIS) and linear polarization results showed that the Ni-PPy treatment decreased the charge-transfer resistance and increased the exchange current density greatly, far more than the single-component Ni or PPy treatment. Consequently, a notable improvement in high rate dischargeability(HRD) was observed, and at a high discharge current density of 1800 mA/g, the HRD of the modified electrode increased by 10.4% compared with that of the bare electrode.

Opening of Band Gap of Graphene with High Electronic Mobility by Codoping BN Pairs

REN Xiangyang, XIA Sha, ZHANG Zhiguo, MENG Xing, YU Hongmei, WU Qi, ZHANG Wenyi, LI Aiwu, YANG Han

2019, 35(6): 1058-1061. doi:10.1007/s40242-019-9151-0

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Two-dimensional(2D) materials with a high density and low power consumption have become the most popular candidates for next-generation semiconductor electronic devices. As a prototype 2D material, graphene has attracted much attention owing to its stability and ultrahigh mobility. However, zero band gap of graphene leads to very low on-off ratios and thus limits its applications in electronic devices, such as transistors. Although some new 2D materials and doped graphene have nonzero band gaps, the electronic mobility is sacrificed. In this study, to open the band gap of graphene with high electronic mobility, the structure and property of BN-doped graphene were evaluated using first-principles calculations. The formation energies indicate that the six-membered BN rings doped graphene has the most favorable configuration. The band structures show that the band gaps can be opened by such type of doping. Also, the Dirac-cone-like band dispersion of graphene is mostly inhibited, ensuring high electronic mobility. Therefore, codoping BN into graphene might provide 2D materials with nonzero band gaps and high electronic mobility.

A New Strategy for Improving the Efficiency of Low-temperature Selective Catalytic Reduction of NO_x with CH₄ via the Combination of Non-thermal Plasma and Ag₂O/TiO₂ Photocatalyst

WANG Hui, WANG Jiafeng, ZHANG Lei, YU Qinqin, CHEN Zewen, WU Shengji

2019, 35(6): 1062-1069. doi:10.1007/s40242-019-9141-2

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In the present work, a remarkable combination of non-thermal plasma and photocatalyst was developed to widen the operating temperature window of selective catalytic reduction(SCR) of NO_x with CH₄, especially to improve the low-temperature removal efficiency of NO_x. It was shown that the operating temperature window was significantly widened. Among all the catalysts prepared, 1%Ag₂O/TiO₂ showed the highest catalytic activity for NO_x removal due to the utilization of near ultraviolet light. The conversion of NO_x to N₂ over the in-plasma 1%Ag₂O/TiO₂ photocatalyst at 60 and 300℃ could achieve 31.8% and 53.0%, respectively. The combination mode of plasma and catalyst affected NO_x removal efficiency greatly, the in-plasma catalysis outperformed the post-plasma catalytic mode remarkably, signifying the contribution of photocatalytic processes on the catalysts. Meanwhile, the characterizations of the catalyst demonstrated that the morphology and structure of the Ag₂O/TiO₂ catalyst were unchanged throughout the non-thermal plasma and photocatalytic processes, implying the superior stability of the catalyst.

Investigation of Voids in Polyacrylonitrile Fibers by USAXS and SAXS

TANG Haitong, MENG Fanling, LIU Yan, JIN Shi, WANG Xiaodong, GAO Zhongmin, CHE Xiaolei

2019, 35(6): 1070-1075. doi:10.1007/s40242-019-9202-6

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The void structure of polyacrylonitrile(PAN) fibers was investigated using ultra-small angle X-ray scattering(USAXS) and small angle X-ray scattering(SAXS). A quantitative method was developed to analyze connected USAXS/SAXS data and thus determine the void parameters of PAN fibers. The results showed that voids affected the mechanical performance of PAN fibers and were present throughout the entire wet-spinning process. When the absolute quantity and size of voids decreased, the tensile strength and modulus of PAN fibers increased. The void parameters were optimized by controlling the production process, and thus the tensile strength and modulus of PAN fibers were increased. The method for analyzing the void structure developed in this study is useful for analyzing voids over with larger size range, as well as the effect of the void structure on the mechanical performance of fibers.

Synthesis, Thermal Degradation and Dielectric Properties of Poly[octyl(triphenylethynyl)]silane Resin

WANG Yanli, TAN Dexin

2019, 35(6): 1076-1081. doi:10.1007/s40242-019-9170-x

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Octyl(triphenylethynyl)silane monomer(OTPES) was synthesized with ethyl bromide, octyltrichlorosilane and phenylethylene by Grignard reaction. The molecular structure was confirmed by FTIR and NMR. The poly[octyl(triphenylethynyl)]silane resin(POTPES) was prepared by thermal polymerization and the corresponding thermal degradation behavior wasstudied by thermogravimetric analysis(TG) combining with model and model-free fitted methods. The dielectric property of resin was also studied by vector network analyzer. The results show that the melt point of OTPES was 50℃ and the processing window was over 236℃. The resin degradation temperature of T_d5 occurred over 433℃ and the char yield was over 60% at 800℃. Based on Kissinger, Flynn-Wall-Ozawa, Coats-Redfern, Achar, Vyazovkin-Wight and Tang methods, the reaction activity(E) was 155.51, 152.97, 150.82, 146.02, 148.38 and 148.77 kJ/mol, respectively. Dielectric properties analysis displayed that the real part(ε') and the imaginary part(ε″) of the relative complex permittivity of POTPES was 2.5 and 0.05, respectively, and the dielectric loss tangent was between 0.03 and 0.25. The reflection loss of resin was more than -2.85 dB in all range of 1-5 mm thicknesses and 2-18 GHz frequency, which indicated that POTPES resin was a real wave-transparent resin matrix.

Demulsification-induced Fast Solidification: a Novel Strategy for Preparation of Polymer Encapsulations

WANG Dan, GE Xingshi, ZHANG Jianfu, SU Zhongmin

2019, 35(6): 1082-1088. doi:10.1007/s40242-019-9167-5

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Encapsulations are being increasingly investigated in both academic research and industrial manufac-turing and applied in numerous fields, such as phase change materials and smart materials. In this paper, a novel strategy of demulsification-induced fast solidification(DIFS) was proposed for the rapid fabrication(within 1 s) of polymer encapsulations via immersion of demulsifier particles in emulsion. The DIFS method allowed the fabrication of three-dimensional(3D) hollow polymer encapsulations with precisely controlled size and thickness over a wide range from micron to millimeter within just 1 s. Magnetic nanoparticles and luminescent materials were further introduced into 3D hollow polymer encapsulations via facile blending method. Moreover, encapsulated paraffin phase change materials with good thermal stability were also obtained using the DIFS method. Therefore, this work provides new insights into the design and preparation of functionalized encapsulation materials.

Ethylene/1-Hexene Copolymerization with Modified Ziegler-Natta Catalyst

YIN Meng, ZHANG Zhiqiang, XIONG Yujie, LIU Min, ZHANG Yan, MI Puke

2019, 35(6): 1089-1094. doi:10.1007/s40242-019-9114-5

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Siloxane compounds were treated with the compounds containing internal donors, such as aromatic ester, phosphate, or 1,3-diether compounds, and the resulting intermediates were further reacted with TiCl₄ to form the modified Ziegler-Natta catalysts for ethylene/1-hexene(E-H) copolymerization. Using the modified Ziegler-Natta catalysts, the effect of the internal donors and the molar ratio of alcohol to magnesium on the catalyst performance was investigated by the orthogonal experiments. The synthetic method of the catalysts was also optimized by choosing the proper way to mix the internal donors. The branch degree, sequence structure, molecular weight, and molecular weight distribution of the copolymer products were determined by Fourier transform infrared spectroscopy(FTIR), carbon-13 nuclear magnetic resonance(¹³C NMR) spectrometry and gel permeation chromatography(GPC). Under the optimum conditions, the catalytic system with tetraethyl orthosilicate and 2,2-dimethoxypropane as the internal donors exhibited the best performance with an activity of 926.74 g copolymer/(g Cat·h^-1). The branch degree, 1-hexene content, and molecular weight distribution of the resulting copolymers reached up to 40 branches/1000C, 5.99% and 5.8, respectively.

Decontamination of Chemical Warfare Agents by Novel Oximated Acrylate Copolymer

WEN Xianfang, YE Lin, CHEN Likun, KONG Lingce, YUAN Ling, XI Hailing, ZHONG Jinyi

2019, 35(6): 1095-1104. doi:10.1007/s40242-019-9105-6

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A novel acrylate copolymer, polymethylacrylate-β-(bromoacetyl ethyl)ester-co-N,N-dimethylacrylamide[P(MABE-co-DMAA)] was synthesized by the copolymerization of N,N-dimethylacrylamide and methylacrylate-β-(bromoacetyl ethyl)ester. Subsequently, the copolymer was oximated by 4-pyridinium aldoxime(4-PAM), and was abbreviated as PAM-P(MABE-co-DMAA). A maximum oxime conversion of 53.7% was obtained. The as-prepared oximated copolymer PAM-P(MABE-co-DMAA) effectively decontaminated chemical warfare agents(CWAs) including methylphosphonofluoridate(sarin or GB), S-2-(diisopropylamino)ethyl O-ethyl methylphosphonothioate (VX), and 2,2'-dichloroethyl sulfide(sulfur mustard, or HD). The detoxification rates were 90.6% for GB, 85.7% for VX, and 90.5% for HD. Chromogenic analysis, high performance liquid chromatography-mass spectrometry (HPLC/MS) and gas chromatography-mass spectrometry(GC/MS) were used to identify the decontamination products, and the decontamination mechanism was concluded to be a combination of nucleophilic substitution and a second order Beckmann rearrangement. Furthermore, the active decontamination materials, such as decontamination cloths and covers could be made from the oximated copolymer by virtue of its processability, as well as its strong ability to degrade CWA.

Tea Polyphenols Reducing Lipopolysaccharide-induced Inflammatory Responses in RAW264.7 Macrophages via NF-κB Pathway

SU Siyi, LI Xiaoyu, GUO Xu, ZHOU Ruiming, LI Manman, MING Pengfei, HUANG Yingying, Sajid Ur RAHMAN, DING Hongyan, FENG Shibin, LI Jinchun, WANG Xichun, LI Yu, WU Jinjie

2019, 35(6): 1105-1110. doi:10.1007/s40242-019-8376-2

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The anti-inflammatory activity of tea polyphenols(TPs) in RAW264.7 macrophages stimulated by lipopolysaccharide(LPS) was investigated in this paper. RAW264.7 macrophages were treated with different concentrations of TP(0, 12.5, 25, 50, 100, and 200 μg/mL) and then stimulated by LPS. Another blank control group was set up. The expression of pro-inflammatory cytokines associated with the nuclear factor-kappa B(NF-κB) signaling pathway was investigated before and after TP treatment. Pretreatment of RAW264.7 cells with TP decreased the expression of tumor necrosis factor-α(TNF-α), interleukin-6(IL-6) and interleukin 1 beta(IL-1β) pro-inflammatory cytokines. In addition, TP inhibited the phosphorylation of p65 and IκB by blocking the phosphorylation and the degradation of NF-κB inhibitor protein. In conclusion, TP exerts anti-inflammatory effects by regulating the release of inflammatory mediators via the NF-κB signaling pathway.

A Strategy to Find Novel Candidate DKAs Inhibitors Using Modified QSAR Model with Favorable Druggability Properties

ZHANG Xiaoyi, NIU Wenling, TANG Tang, HOU Chengfei, GUO Yajie, KONG Ren

2019, 35(6): 1111-1118. doi:10.1007/s40242-019-9183-5

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The study dealed with quantitative structure-activity relationship(QSAR) to explore the important features of diketo acid(DKA) derivatives for exerting potent HIV-1 integrase inhibitors activity. A three-step screening method was proposed to choose descriptors. Then, additional descriptors were used in the CoMFA and CoMSIA. Lastly, a modified CoMSIA m7 model, constructed by adding C_sp²_03_F descriptor, showed better predictive ability. Validation parameters(Q² and R²) for the models were 0.722 and 0.925, respectively. In addition, external validation for the models using a test group revealed R_pred²=0.892. Contour maps analysis defined favored and disfavored regions of the compounds, and two new compounds with the descriptor structure were designed with better activities than Ralte-gravir(RAL), well drug-likeness and low toxicity. The research provides a base for further DKA development.

Influence of Nucleotide-biased Fluorescence Emissions of SYBR Green II on the Result Consistence of Rolling Circle Amplification

ZHANG Bin, JIANG Jiquan, YUAN Ying, GUAN Yifu

2019, 35(6): 1119-1123. doi:10.1007/s40242-019-9223-1

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The fluorescence dye SYBR Green II(SG II) has been frequently used in rolling circle amplification(RCA) based analyses of nucleic acids. However, a good amount of inconsistencies have been reported in regards the quality and reproducibility of RCA reactions. To properly examine this experimental issue, here we utilized a series of synthetic oligonucleotides and circular templates to investigate the impact of SG II in RCA reactions. The results indicate that SG II enables a strong fluorescence signal only when complexing with guanosine(G) residue. In RCA reactions, long single-stranded RCA products, enriched with G residues, result in higher fluorescence emission when compared with the addition of other nucleotide residues. These results suggest that the nucleotide composition of the reaction can affect the amplification results and, eventually, can lead to inconsistent fluorescence of the RCA products. This work indicates that particular attention should be given when circular templates are designed for the quantitative analysis of nucleic acids, to further allow the signal reproducibility of RCA-based experiments.

Improving Elasticity of Conductive Silicone Rubber by Hollow Carbon Black

ZHANG Jihua, CHEN Fengbo, ZHAO Yunfeng, LIU Mingjie

2019, 35(6): 1124-1132. doi:10.1007/s40242-019-9057-x

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Carbon black-based conductive rubber composites have important impacts on electromagnetic interference(EMI) shielding applications. However, an excessive amount of carbon black in the recipes of these conductive rubbers has caused their weak elasticity. Herein, hollow carbon black(HCB) particles were used to tune the elasticity of conductive rubber composites. Unique hollow morphology produced a better compression recovery of HCB than other solid carbon black, such as acetylene black. When the coupling agent was bonded to HCB, their conductive silicone rubber composites were featured by high stretching resilience, a fast compression recovery and excellent conductivity to satisfy the electromagnetic interference shielding requirements. Importantly, the rubber composites with coupling HCB had extremely low variations of mechanical property, conductivity and EMI shielding effectiveness after thermal accelerated aging tests. It is therefore revealed that the elasticity of HCB and its interfacial chemical coupling with rubber chains both play crucial roles in adjusting the elasticity of conductive rubber to sever long-term EMI protection.

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