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10 January 2018, Volume 39 Issue 1

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Cover and Content of Chemical Journal of Chinese Universities Vol.39 No.1(2018)

2018, 39(1):  0-0. 

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Review

Progress in Hydrogels Based on Regenerated Silk Fibroin^†

LONG Xingtong, GUAN Juan, CHEN Xin, SHAO Zhengzhong

2018, 39(1):  1-11.  doi:10.7503/cjcu20170635

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Regenerated silk fibroin(RSF) is a fibrillar protein obtained from Bombyx mori silkworm silk. Recently, RSF-based hydrogels have attracted extensive research interest, which has yielded an improved understanding in the gelling mechanisms, physical and mechanical properties as well as the applications in regenerative medicine and tissue engineering. Mechanistically, RSF hydrogel networks can be formed via two pathways, chemical cross-linking including enzymatic cross-linking, and physical cross-linking through conformational transition, during which thermodynamically more stable β-sheet structures are induced. An advantage of RSF hydrogels is that the physical and mechanical properties of hydrogels can be further controlled by the β-sheet content in the conformation on top of concentration and cross-linking density. RSF can be mixed with other polymers and/or inorganic components to prepare composite hydrogels for a wider spectrum of mechanical properties. Furthermore, we summarize most recent applications of RSF hydrogels in biomaterials, including controlled drug release, muscle, tendon and bone tissue engineering.



Articles: Inorganic Chemistry

Influence of Environment Change Around N-atom on the Structure-directing Effect of Methylamine in the Synthesis of Open-framework Aluminophosphates^†

CHANG Xiaowen, YAN Wenfu, SHI Wei, XU Ruren

2018, 39(1):  12-18.  doi:10.7503/cjcu20170590

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By heating the initial mixture with the molar composition of n(Al₂O₃):n(P₂O₅):n(R):n(H₂O)=1:1:1:277(R=methylamine or dimethylamine) at 200 ℃, highly crystalline three-dimensional anionic open-framework aluminophosphate of AlPO₄-53 or AlPO₄-21 was obtained. Protonated methylamine and dimethylamine were located in the framework of AlPO₄-53 and AlPO₄-21 to balance the negative charge of the framework, respectively. The crystallization processes of both initial mixtures were investigated by X-ray diffraction analysis(XRD), elemental analysis and pH measurement. Theoretical calculation shows that the charge on the N atom of protonated methylamine and dimethylamine is -0.263 and -0.558 e(Mulliken), respectively. The corresponding formal charge density is 22.3 and 16.0 e/nm³, respectively. The framework charge density of AlPO₄-53 and AlPO₄-21 is -3.3 and -3.1 e/nm³, respectively. These results indicate that the environment change around N atom can affect the amount of charge on it, which accordingly affects its structure-directing ability. A charge matching between the formal charge density of organic amines and the framework charge density was observed.



Synthesis of Organodiphosphonate MOFs-derived Ni₂P/C Composite^†

XU Dan, XIAO Shanshan, WU Pan, PAN Ying, CHEN Lihua, SU Baolian, XUE Ming, QIU Shilun

2018, 39(1):  19-24.  doi:10.7503/cjcu20170551

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Ni and organodiphosphonate-based metal organic framework(Ni-MOF) was synthesized under hydrothermal condition using p-xylylenediphosphonate as the organic ligand. Then, Ni-MOF was selected to prepare the amorphous carbon coated Ni₂P composite materials by facile method. The composite material retained the lamellate shape of the precursor, and the BET surface area reached 202 m²/g. The Ni₂P nanoparticles in the composites had good crystallinity, and the particles were homogeneous and had no reunion. In the performance of lithium ion battery, the Ni₂P/C composite structure improved the electron and ion conductivity of the material while reducing the volume expansion of the material, thus improving the electrochemical properties of the material. The first charge and discharge capacity of Ni₂P/C composite material were 247 and 226 mA·h·g^-1, respectively, coulombic efficiency can reach 91.7%, and the coulombic efficiency reaches 100% after 200 cycles.



Preparation and Luminescence Properties of Na⁺, Li⁺, Bi³⁺ Doped CaWO₄:Eu³⁺ Phosphors^†

WANG Linxiang

2018, 39(1):  25-31.  doi:10.7503/cjcu20170406

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Na⁺, Li⁺, Bi³⁺ doped CaWO₄:Eu³⁺ phosphors were synthesized by microwave-assisted heating solid state reaction method. The microstructures of the sampless were characterized by XRD and SEM. The excitation spectra, emission spectra and energy levels of the samples were detected and analyzed by fluorescence spectrophotometer. The results showed that the samples all kept the tetragonal matrix. Compared with the particle size of CaWO₄:Eu³⁺phosphor, the size of Na⁺, Li⁺, Bi³⁺ doped or codoped CaWO₄:Eu³⁺ phosphors all increased. Under 393 nm excitation, the luminescence intensities of samples doped with Na⁺ and Li⁺ are 1.8 and 1.2 times that of undoped these ions, and the luminescence intensities all decreased for the sample codoped with Li⁺, Na⁺ and the sample codoped with Li⁺, Bi³⁺. Under 254 and 393 nm excitation, the lifetime of the sample doped with Li⁺ was the shortest in all samples. For the same sample, the energy level lifetime under the 393 nm excitation was shorter than that under the 254 nm excitation.



Analytical Chemistry

Programming Single Quantum Dot Valencies via DNA Caging^†

WANG Li, LI Zhi, SHEN Xiaoqin, MA Nan

2018, 39(1):  32-40.  doi:10.7503/cjcu20170539

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A fundamental unsolved problem for quantum dot(QD) chemistry is to simultaneously control the type, number and spatial orientation of QD valencies(i.e., the binding sites on each QD). Herein, we demonstrate a strategy to generate structurally predicable multivalent QD with uniform valency type, number and spatial orientation by caging the QD in a DNA cube by DNA nanotechnology. The results show that diffe-rent DNA valencies could be anchored to specific positions of the cube to form homogeneous DNA-functiona-lized QD with adjacent or diagonal valencies. As a proof-of-concept study, different sizes of gold nanoparticles(GNPs) were conjugated to each QD valency through DNA hybridization. The resulting bivalent and trivalent QD conjugates not only possess the same GNP number but also uniform assembly geometry by low magnification and high-resolution TEM. This approach holds great potential for generating multivalent and multifunc-tional QD probes for advanced biological applications.



Detection of C-reactive Protein by Background Fluorescence Quenching-Immunochromatography^†

CHEN Junlei, ZHANG Wei, LI Xinxia, LI Jiutong, GUAN Ming

2018, 39(1):  41-47.  doi:10.7503/cjcu20170494

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fluorescence immunochromatography assay(bFQICA) has been established, which has the advantages of simple operation, high sensitivity, strong anti-interference and rapid quantitative detection of C-reactive protein(CRP). This method of using double antibody sandwich method principle, the appropriate concentration of capture antibody and tracer antibodies are respectively fixed on the test strip and the micropore. During chromatography, antibodies were captured, while tracer antibodies and samples were inserted to form a sandwich structure of antibody antigen antibody. The method has a good correlation with fluorescence signal values(F₁/F₂) in the range of 0.0—100.0 ng/mL concentration in CRP, the minimum detection limit was 0.0939 ng/mL, and the recovery rate was 87.69%—111.0%, three batches of reagents and inter and intra assay relative standard deviation was less than 15%, and procalcitonin(PCT, 20.0 ng/mL), serum amyloid A like protein(SAA, 10.0 μg/mL) had not cross reaction with this method and the immune turbidimetric method for the simultaneous determination of 41 serum samples, the detection results had a good correlation(r=0.9585, P<0.01), there was no significant difference between the two methods(P>0.05). This method has high sensitivity, simple operation, and can be used for rapid and accurate quantitative detection of CRP.



Active Conformation of DNA Aptamer Against Recombinant Human Erythropoietin-α^†

HE Xiaoqin, HE Junlin, XU Hua, GUO Lei, XIE Jianwei

2018, 39(1):  48-53.  doi:10.7503/cjcu20170312

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A series of spectroscopic techniques such as surface plasmon resonance, circular dichroism and fluorescence was employed to illustrate the relationship between the binding activity and conformation of the shortest aptamer In27 against recombinant human erythropoietin-α(EPO-α). It was found that the presence and concentration of sodium cation were the key factors that affected the specific affinity recognition of aptamer In27. Sodium cation induced aptamer In27 to form a parallel/antiparallel hybrid G-quadruplex(GQ) conformation. GQ-specific fluorescent probe thysmenonine T(ThT) specifically bound to the hybrid GQ conformation of aptamer In27. The addition of EPO-α could compete with ThT to facilitate to create a label-free fluorescent “turn-off” probe for EPO-α. This research provides an effective combination of techniques for elucidating the active conformation of novel aptamers, and provides a kind of aptameric modules with clear interaction features for analytical, sensing and diagnostic applications.



Organic Chemistry

Preparation of Combined Cross-linked Enzyme Aggregates and Its Application in Synthesis of Chiral Alcohols by the Asymmetric Reduction of Carbanyl Group^†

YANG Meng, JIANG Huijuan, NING Chenxi, WEI Dongzhi, SU Erzheng

2018, 39(1):  54-63.  doi:10.7503/cjcu20170509

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Using ketoreductase KRED 30 from Corynebacterium sp. and the D-glucose dehydrogenase from Bacillus subtilis as the model enzymes, a combined cross-linked enzyme aggregates(combi-CLEAs) with high activity was prepared by optimization of the precipitant type, glutaraldehyde concentration, cross-linking temperature and time. Characterization of the combi-CLEAs showed that the stability and substrate tolerance of free enzymes mixture were significantly improved after combined cross-linking. Investigation of catalytical performance showed that combi-CLEAs could effectively catalyze the reduction of ethyl 4-chloroacetoacetate(COBE) and 3'-chloroacetophenone(CPO) for the synthesis of corresponding chiral alcohols in aqueous system. Only a little cofactor was needed to start the reactions. The catalytical activity could retain more than 70% after continuously catalyzing for 10 batches. The result showed that catalytical performance of combi-CLEAs in the biphasic system was much better than that in aqueous system. The total turnover number(TTN) for catalyzing COBE could attend 6595, and TTN for catalyzing CPO could attend 7500. Thus, cofactor regeneration by combi-CLEAs is feasible.



Synthesis and Biological Activity of Tyrosol Ester Derivatives^†

ZANG Hao, SHEN Peng, WANG Enpeng, XU Qian, ZHANG Luyun, XIA Guangqing, ZHU Junyi, ZHANG Hui, YANG Xiaohong

2018, 39(1):  64-70.  doi:10.7503/cjcu20170391

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A series of tyrosol derivatives was synthesized via the modification of alcohol hydroxyl groups of tyrosol, twenty-five target compounds were obtained and characterized by NMR and HR-MS. The experimental results show that most compounds exhibit some 1,1-diphenyl-2-picrylhydrazyl(DPPH) scavenging activities, compounds 3k and 3y have good DPPH scavenging activities, especially compound 3y shows the highest DPPH scavenging activities which is stronger than 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid(Trolox). The results show that most compounds exhibit some 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium(ABTS) scavenging activities, compounds 3k, 3x and 3y have good ABTS scavenging activities, especially compound 3y shows the highest ABTS scavenging activities which is stronger than Trolox. Ferric reducing antioxidant power(FRAP) experimental results show that most compounds exhibited some reduction activities to ferric ion-2,4,6-tri(2-pyridyl)-s-triazine(Fe³⁺-TPTZ) complex, compounds 3k, 3w and 3y have good reduction activities to Fe³⁺-TPTZ complex, especially compound 3y shows the highest reduction activities to Fe³⁺-TPTZ complex which is stronger than Trolox.



Effect of Curcumin on Yeast Cells by Fluorescence Analysis^†

CHEN Jingxin, LIAN Wenhua, CHENG Yuanchu, XU Jianhua, ZHANG Lianru

2018, 39(1):  71-77.  doi:10.7503/cjcu20170381

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The simplest eukaryotic Saccharomyces cerevisiae was studied as the material, with the help of fluorescence properties of curcumin, using fluorescence spectroscopy and fluorescence microscopy to observe the localization of curcumin in yeast cells and its impact on yeast growth. The results show that curcumin can enter the yeast cells bind to yeast mitochondrion and inhibit the growth of yeast with a dose and time depend manner. This study provides a basis for further study of how curcumin can influence the cell metabolism by its combination to mitochondria and its relationship with cell apoptosis.



One-pot Electrochemical Oxidation Synthesis of Nitriles from Alcohols with Hexamethyldisilazane as the Nitrogen Source^†

FAN Zhongquan, CHEN Chen, SHEN Zhenlu, LI Meichao

2018, 39(1):  78-84.  doi:10.7503/cjcu20170245

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One-pot electrochemical oxidation synthesis of nitriles from alcohols was developed with hexamet-hyldisilazane(HMDS) as the nitrogen source, 2,2,6,6-tetramethylpiperidinyl-1-oxy(TEMPO) as the electrooxidation medium at the room temperature. The catalytic performance of TEMPO was studied by cyclic voltammetry, and the oxidation process was monitored by in situ FTIR analysis. Under the optimized conditions, the constant potential electrolysis of various alcohols, especially of benzylic alcohols, afforded the corresponding nitriles in moderate to excellent yields. Finally, the corresponding reaction mechanism of one-pot electrochemical oxidation of alcohols to nitriles was proposed.



Physical Chemistry

Dissipative Particle Dynamics Simulations on the pH-responsive Gating of Block Copolymer Brush Modified Nanopores^†

WANG Li, WANG Chu, ZHOU Jian

2018, 39(1):  85-94.  doi:10.7503/cjcu20170493

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Dissipative particle dynamics(DPD) was adopted to investigate the smart gating of nanopores grafted with pH-responsive block copolymers[polyacrylic acid(PAA)-poly 2-vinyl pyridine(P2VP)]. Effects of different block sequences Wall-P2VP-PAA, Wall-PAA-P2VP on the smart gating was studied. The results show that only the Wall-PAA-P2VP block sequence can form smart gates under different pH values. Grafting density is an important factor on structures of smart gates; only with moderate grafting densities, can smart membranes be formed. The chain length is another important factor affecting the smart gating. It shows that the “closed” state of smart membranes cannot be formed with short chain lengths; however, the “closed” state can be formed by polymers with longer chain lengths. Under proper grafting density and chain length of block polymers, different-sized smart membranes can be formed under different pH values; the smart gate can be switched from the “open” state to the “closed” state. Finally, the effect of block ratio on smart gating was also studied. The results show that the size of the block-copolymer-brush-grafted nanopore decreases gradually with the increase of PAA proportion and finally the “closed” states are almost formed. This work provides a theoretical basis for designing and constructing nanopores with smart gates.



Skeletal and Reduced Mechanisms of Methane at O₂/CO₂ Atmosphere^†

HU Xianzhong, YU Qingbo, LI Yanming

2018, 39(1):  95-101.  doi:10.7503/cjcu20170458

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A skeletal and a reduced mechanism of methane at O₂/CO₂ atmosphere were developed. A skeletal mechanism with 24 species and 126 reactions was obtained from detail mechanism GRI Mech 3.0 via directed relation graph method. Then, a reduced mechanism was developed from the skeletal mechanism with quasi steady state approximation, which consist of 17 species and 14 reaction steps. The predictions of different kinds of flames using the skeletal and the reduced mechanism are almost identical with that using the detailed mechanism.



Organic Phototransistor Based on Surface Plasmon Resonance Effect^†

ZHANG Chanchan, ZHANG Fanghui, DING Lei, NI Zhenjie, JIANG Lang, DONG Huanli, ZHANG Xiaotao, LI Rongjin, HU Wenping

2018, 39(1):  102-108.  doi:10.7503/cjcu20170377

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Photoresponsive organic field-effect transistors(PhotOFET) require materials with high mobility, high absorbance and high exciton dissociation efficiency. Although great efforts have been made to realize high performance PhotOFET using various organic small molecules and polymeric semiconductors, both the responsivity and mobility were still low based on pristine materials. In this work, gold nanoparticles(Au NPs) were incorporated into the semiconductor layer of OFET. Owing to the surface plasmon effect of the Au NPs, the absorbance of the semiconductor could be greatly increased and high-performance PhotOFET were realized. Au NPs were prepared in situ on the substrates and used to fabricate PhotOFET directly. By utilizing the surface plasmon resonance effect of the Au NPs, high performance PhotOFET with a mobility of 0.12 cm²·V^-1·s^-1 and a responsivity of 11.6 A/W was obtained based on the materials without photoresponse in the visible spectrum. The surface chemical modification of gold nanoparticles with alkane thiol played a key role in improving the device performance. The device structure proposed here, i. e. the incorporation of Au NPs into the semiconductor layer of OFETs, provided an effective method for the construction of high performance PhotOFET based on common organic semiconductors.



Organic Chemistry

Self-propelled Droplet Movement on Micro/nano Anisotropic Structures Surface^†

LI Dan, ZHENG Yongmei

2018, 39(1):  109-114.  doi:10.7503/cjcu20170329

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The micro/nano anisotropic structures was controllably fabricated by soft lithography using polydimethylsiloxane(PDMS) and Co nanoparticle composite under the external magnetic field and covering of ZnO nanohairs via nanocrystalline growth technique. The sample is covered with periodicities of ca. 400 μm conical fibers and the conical fibers diameter of ca. 200 μm. The tip diameter of cone is ca. 80 μm. The length of the cone is ca. 1 mm. The ZnO nanohairs cover fully over every fibers, where the ZnO nanohairs have the diameters of 80—100 nm and the lengths of ca. 1 μm. The sample is hydrophobic with a contact angle of 142.5° andanisotropic wettability. The result indicates that the droplets can roll under vertical vibration or bounce directionally. This finding offers an insight into design of functional structures for droplets move in direction.



Physical Chemistry

Application of Hybrid Modified PAN Nanofibrous Membrane Fe Complexes with Adsorption-photocatalysis Bifunctions for Removal of Organic Dye from Water^†

LI Fu, DONG Yongchun, CHENG Bowen, KANG Weimin

2018, 39(1):  115-123.  doi:10.7503/cjcu20170281

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Polyacrylonitrile nanofibrous(n-PAN) membrane were prepared by electrospun method and modified with different molar ratios of hydroxylamine(HA) and/or hydrazine hydrate(HH). The resulting modified n-PANs were then coordinated with Fe³⁺ ions to fabricate five modified n-PAN Fe complexes with different surface structures. The effect of HH addition on the complex preparation and its removal performance of azo dye Reactive red 195 from water were investigated and compared. The results indicated that the modified n-PAN fibrous diameter and Fe content of its Fe complex decreased as the addition of HH increased. This lead to a better adsorption and photocatalytic degradation capacities of three hybrid modified n-PAN Fe complexes. Thus, the rapid removal of dye molecules from aqueous solution was obtained through combination of both functions of the complexes mentioned above.



Effect of Substrate Surface Wettability on the Adsorption of Magnetic Carrier/Protein Nanocomposites^†

HU Qian, DING Yadan, PAN Ying, HONG Xia

2018, 39(1):  124-131.  doi:10.7503/cjcu20170241

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Hydrophobic ZnO seed layer and superhydrophobic ZnO nanowire array were grown on glass substrate, respectively. The adsorption of the magnetic carrier/bovine serum albumin(BSA) nanocomposites could reach a maximum saturation level upon applying an external magnetic field. The magnetic separation efficiencies using the ZnO nanowire array as the separation substrate were proved to be much higher than those using glass or the ZnO seed layer as the separation substrate. And the difference became large with the decrease of the nanocomposite concentrations. It might be attributed to the small solid-liquid contact area of the superhydrophobic substrate and its strong flow shear. The target protein was then further expanded to the other two typical proteins with different properties, i.e., hemoglobin and lysozyme. And the results proved that the effect rule of the substrate surface wettability on protein adsorption was universal. The superhydrophobic substrate has a more obvious advantage in improving the magnetic separation efficiency than commercial glass, polypropy-lene and hydrophobic substrate, and exhibited outstanding magnetic separation efficiencies for “hard” proteins. The present work could contribute to a better understanding of the effect of the interfacial property on protein adsorption behavior, and open up a new avenue to fabricate highly efficient protein separation platform.



Preparation and Electro-catalytic Mechanisms for Nitrate Ion Reduction of Ti_(100-δ)Cu_δ(δ=0.02, 0.09, 0.28, 1.39, 5.65) Cathodes^†

KONG Yan, WANG Lizhang, YANG Shengxiang, ZHAO Peng

2018, 39(1):  132-140.  doi:10.7503/cjcu20170229

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The ectopic electro-deposition method was used to prepare Ti_(100-δ)Cu_δ cathodes with various mass fraction(δ) of 0.02, 0.28, 1.39 and 5.65, respectively, over titanium plates under different electro-deposition time. The scanning electron microscope(SEM), X-ray diffraction(XRD), electrochemical tests including cyclic voltammetry, linear sweep voltammetry and Tafel plots on an electrochemical workstation and nitrate ion reduction experiments were performed to characterize and investigate the microstructure, physical composition, electro-catalytic reduction performance, corrosion resistance and the products selectivity. The experimental results indicate that the active layer existing on the surface of Ti_(100-δ)Cu_δ cathodes presents as lattice pattern (111) if the value of δ is no less than 0.28, which can effectively improve the stability of the active layer. The existence of the active layer provides additional active sites for adsorption of nitrate ion(N\begin{array}{c}{O}_3^{-}\end{array}), which enhances the electro-catalytic performance of cathodes; however, the involvement of copper element would reduce the corrosion resistance of cathodes compared with that of Ti electrode. Besides, Cu exhibits a certain negative effect on the adsorption of nitrite ion while enhances the reduction activity of nitrite ion thus improving selectivity of nitrogen gas. The results of nitrate treatment experiments using Ti_(100-δ)Cu_δ(δ=5.65) cathodes at current density of 20 mA/cm² and reaction time of 6 h illustrate that nitrate removal and the selectivity of N₂ were 75.47% and 32.65%, respectively, but as a comparison only 39.89% and 2.19% of those variables were obtained on a titanium electrode at the same experimental conditions.



Preparation and Electrochemical Performance of LiNi_1/3Co_1/3Mn_1/3O₂@C Composite^†

WANG Kun, HUANG Mengyi, ZHANG Xiaosong, HUANG Junjie, DENG Xiang, LIU Changlu

2018, 39(1):  141-147.  doi:10.7503/cjcu20170215

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Carbon coated LiNi_1/3Co_1/3Mn_1/3O₂(NCM@C) was prepared by active carbon to adsorb the mixed solution of acetate salts of Co²⁺, Mn²⁺, Ni²⁺ and Li⁺. Transmission electron microscopy(TEM) image shows that the surfaces of LiNi_1/3Co_1/3Mn_1/3O₂ particles are homogeneously coated by carbon with a thickness about 10 nm. The initial discharge capacity of NCM@C is 181 mA·h/g at 0.2C, and its initial Columbic efficiency is 90.7%. Meanwhile, the discharge capacity of NCM@C is 78 mA·h/g at 20C, while it is only 39 mA·h/g for LiNi_1/3Co_1/3Mn_1/3O₂(NCM) that prepared by a co-precipitation method. NCM@C also shows good cycling stability, the capacity retention is 88.1% after 50 cycles at 0.2C, while it is only 66.4% for NCM.



Synthesis and Characterization of Full Concentration-gradient LiNi_0.643Co_0.055Mn_0.302O₂ Cathode Material for Lithium-ion Batteries

LUO Man, JIANG Wenquan, HAN Xue, GUO Ronggui, LI Tao, YU Limin

2018, 39(1):  148-156.  doi:10.7503/cjcu20170198

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The “two-step” method was adopted to realize the continuous gradient change of feed concentration and the gradient design of final material was derived from mathematical calculus formula. The full concentration-gradient precursor was prepared via co-precipitation method and technique of “Tubular synthesis”. The final lithiated cathode material was obtained by calcination of the mixture of as-obtained full concentration-gradient precursor and 6.5% excess LiOH·H₂O in oxygen, whose average chemical compositions was LiNi_0.643Co_0.055Mn_0.302O₂ analyzed by inductively coupled plasma-atomic emission spectrometry(ICP-AES). The LiNi_0.643Co_0.055Mn_0.302O₂ particle was nearly spherical and had the size of 5 μm in diameter with narrow particle size distribution and its tap-density was approximately 2.029 g/cm³. A well-ordered α-NaFeO₂ layer-structured LiNi_0.643Co_0.055Mn_0.302O₂ was confirmed by Rietveld refinement of X-ray diffraction(XRD), in which the lattice parameters were a=0.2877(5) nm, c=1.4242(24) nm, V=0.102088(31) nm³, respectively. Energy dispersive spectrometory(EDS) and element mapping results verified that the concentration of Ni, Co and Mn changed gradually inside out of the particle. LiNi_0.643Co_0.055Mn_0.302O₂ delivered an initial discharge capacity of 187.68 mA·h ·g^-1 and coloumbic efficiency of 84.76%. After cycling at 1C rate for 200 cycles, the discharge capacity and capacity retention of LiNi_0.643Co_0.055Mn_0.302O₂ were 146.45 mA·h ·g^-1 and 86.90%, respectively.



Preparation and Electrocatalytic Performance for Methanol Oxidation of Pt-CeO₂/Sodium-4-styrenesulfonate Functionalized Carbon Nanotube Composites^†

CHEN Chen, LI Li, CHEN Jinhua, ZHANG Xiaohua, XU Jie, LI Yibo, WEI Jie

2018, 39(1):  157-165.  doi:10.7503/cjcu20170168

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Carbon nanotubes(CNTs) were noncovalently modified by anionic polymer poly(sodium-4-styrenesulfonate)(PSS) to obtain PSS functionalized CNTs(PSS-CNTs), and then Ce³⁺ was assembled to CNTs surface through the electrostatic interaction between electropositive Ce³⁺ and electronegative PSS. Through the electrostatic interaction and oxidation-reduction reaction between Ce³⁺and PtC\begin{array}{c}{l}_4^{2-}\end{array}, CeO₂ and Pt nanoparticles were in-situ deposited on the surface of CNTs to obtain PSS-CNTs supported Pt-CeO₂ composite catalyst(Pt-CeO₂/PSS-CNTs). The structure, component and micromorphology of Pt-CeO₂/PSS-CNTs were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), X ray photoelectron spectroscopy(XPS), energy dispersive X-ray spectroscopy(EDS) and Raman spectroscopy, respectively. The electrochemical study shows that, due to the smaller particle size, the better dispersion uniformity and stability of Pt nanoparticles in-situ deposited on the surface of PSS-CNTs compared with those on the original CNTs, and the synergetic effect between Pt and CeO₂, Pt-CeO₂/PSS-CNTs, especially Pt-CeO₂/PSS-CNTs with n_Pt/n_Ce of 2/3, exhibits higher catalytic activity and stability for methanol electrooxidation compared with Pt-CeO₂/CNTs and PtRu/C.



Polymer Chemistry

Single Molecule Force Spectroscopy Study on the Apparent Nanomechanical Properties of Polyethylene Single Crystals^†

LÜ Xiujuan, SONG Yu, ZHANG Wenke

2018, 39(1):  166-171.  doi:10.7503/cjcu20170434

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Semi-crystalline polymers have been widely used as plastic, fiber and elastomers due to their excellent mechanical properties. As is well known, semi-crystalline polymer materials are composed of crystal and amorphous phases, and crystal phase plays very important roles in their mechanical properties. However, it is very difficult to discern the contribution of crystalline phase to the mechanical properties using traditional methods. Here, we study the mechanical properties of single polyethylene(PE) molecule within its single crystal using combined techniques of atomic force microscopy(AFM) imaging and AFM-based single-molecule force spectroscopy(SMFS). The results show that the apparent mechanical stability of single PE chain significantly increased with the increase of the thickness of PE single crystal. The stiffer loading device greatly enhanced the unfolding force of the single PE chain and promoted the formation of intermediates during unfolding process. These results deepen understanding on the origin of mechanical properties of PE single crystal, and may be useful for tuning the mechanical response of corresponding polymer materials.



Fabrication of Microcapsules with Special Shapes by Layer-by-layer Assembly on CaCO₃ Microparticles^†

YANG Hui, LI Tong, TONG Weijun, GAO Changyou

2018, 39(1):  172-177.  doi:10.7503/cjcu20170416

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Biconvex platelet-like and spindle-like calcium carbonate particles were prepared by mixing Na₂CO₃ and CaCl₂ solutions in the presence of poly(allylamine hydrochloride)(PAH) under magnetic stirring and ultrasound treatment, respectively. The platelet-like CaCO₃ particles were vaterites, while the spindle-like ones were mainly aragonites. These two kinds of particles were both doped with small amount of PAH. The formation of CaCO₃ particles with specific shapes was due to the synergistic effect of mixing method and PAH additives. Then platelet-like and spindle-like polyelectrolyte multilayer microcapsules were fabricated via layer-by-layer(LbL) assembly method using the CaCO₃ particles with corresponding shape as templates. The fabricated micrcapsules could be well dispersed in aqueous medium and maintain their original shapes.



Cell Response and Mechanical Properties of the Nanofibers Reinforced Bilayered Tissue Guided Memberanes^†

WANG Zhiwei, HUANG Di, XI Shaohui, XU Mengjie, ZHU Xuefang, LIAN Xiaojie, WEI Yan, CHEN Weiyi

2018, 39(1):  178-184.  doi:10.7503/cjcu20170336

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The bilayer guiding bone regeneration(GBR) membrane used for simultaneous periodontal regeneration was fabricated. Firstly, nano hydroxyapatite/polyamide(nHA/PA) membrane was prepared by thermally induced phase separation. Afterwards, PA nanofibers with different orientation was formed by electrospinning on the surface of the porous nano hydroxyapatite/polyamide(nHA/PA) membrane. The microstructure, orientation and mechanical properties of the PA nanofibers were investigated under different rotational speed(0, 500, 1500 r/min). The results show that porous structure is presented on the surface and inside of the nHA/PA membrane. The nHA crystals distribute uniformly in the PA matrix. The orientation of the PA nanofibers is improved with the increasing of rotation speed. The mechanical testing results show that the elastic strength of the bilayer construct can reach(39.86±4.73) MPa under the rotation speed of 500 r/min. The cell culture results show that the MG63 cells grow well around the bilayer construct. The bilayer constructs display favorable cytocompatibility and show potential clinical applications in the field of periodontal regeneration.



Synthesis and Microwave Absorption Performance of Fe₃O₄@PPy@PANI Composites^†

ZHANG Long, WAN Xiaona, DUAN Wenjing, QIU Hu, HOU Jieqiong, WANG Xiaorui, LI Hui, DU Xueyan

2018, 39(1):  185-192.  doi:10.7503/cjcu20170318

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Polypyrrole(PPy) was used to modify the surface of Fe₃O₄ nanoparticles which was prepared by solvothermal method. Polyaniline(PANI) was used to control the electromagnetic component of Fe₃O₄@PPy composites, and then Fe₃O₄@PPy@PANI composites with core-shell structure were successfully prepared. Modifying Fe₃O₄ nanoparticles with PPy made PANI easily coated on the surface of magnetic nano-particles, and the reasons for this phenomenon were discussed in this paper. The results of the electromagnetic performance analysis show that the minimum reflection loss(RLmin) reaches -39.2 dB when the mass ratio of aniline(An) to Fe₃O₄ @PPy is 1∶4. The bandwidth of reflection loss less than -10 dB is 4.6 GHz when the mass ratio of An to Fe₃O₄ @PPy is 1∶2. The proportion of electromagnetic components have a greater impact on the microwave absorbing properties, which are also described in this article.