JOURNAL OF ANTIBIOTICS
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2019
·Vol. 72
·期 10
·736-743
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IF 2.446
Xi Xuedong,Lu Xingzhong,Zhang Xiaodong,Bi Yuhui,Li Xiaochun,Yu Zhiguo
Two novel depsipeptides xenematides F and G ( 1 , 2 ), were isolated from entomopathogenic Xenorhabdus budapestensis SN84 along with a known compound xenematide B. The structures of the two new molecules were elucidated using NMR, MS and Marfey’s method. The xenematide G ( 2 ) contains α-aminoheptanoic acid, a non-protein amino acid that is rarely found in secondary metabolites from entomopathogenic bacteria. Xenematides F and G were tested for antibacterial activity. Xenematide G ( 2 ) exhibited moderate antibacterial activity.
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EUROPEAN POLYMER JOURNAL
·
2019
·
IF 3.621
Baozheng Tian,Xianwei Zhang,Hong Fan
This paper discusses the synthesis of polyethylene-g-polydimethylsiloxane (PE-g-PDMS) graft copolymers through a facile macromonomer approach. A novel octene-terminated PDMS macromonomer was synthesized via anionic ring-opening polymerization of hexamethylcyclortrisiloxane and the subsequent chain-end capping with dimethyl(oct-7-enyl)chlorosilane. A systematic investigation was conducted on the VCl 3 (THF) 3 /Et 2 AlCl-catalyzed copolymerizations of the PDMS macromonomer with ethylene by varying the macromonomer feed. The relatively high activity of 11.6 kg/(mmol V ·h) was observed even at a rather high macromonomer feed of 160 mmol/L, which is first reported and of great significance in the efficient fabrication of polyethylene-g-polysiloxane graft copolymers. The resulting PE-g-PDMS copolymers were characterized to determine the chain structure, molecular weight and molecular weight distribution. The highest macromonomer incorporation (3.77 mol%) was achieved at the highest macromonomer feed with a decreased molecular weight and a narrower molecular weight distribution. DSC analysis revealed that melting temperature and crystallinity of PE-g-PDMS copolymers systematically decreased with increasing of the PDMS macromonomer incorporation. When quite a small amount (2 wt%) of PE-g-PDMS copolymers was added to HDPE via melt blending, the melt flow rate of HDPE increased by 32% and the mechanical properties remained almost unchanged.
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COMPOSITES SCIENCE AND TECHNOLOGY
·
2019
·
IF 6.309
Yuanyuan Ma,Yu Yang,Chunxiang Lu,Xiaodong Wen,Xingchen Liu,Shijie Wu,Kuan Lu,Junqing Yin
Effects of a novel carbon/phenolic (CF/PR) ablator filled with acidified graphitic carbon nitride (ag-C 3 N 4 ) on ablative resistance were evaluated. Ablative properties of CF/PR composites were significantly enhanced by 69.23% with incorporating 0.2 wt% ag-C 3 N 4 , ascribing to the formation of the dense carbon layer over the fibers, increased graphitization degree and more pyrolysis gases . Molecular dynamics simulations of ag-C 3 N 4 inside the matrix confirm the origins of improved ablation resistance arising from the fact that ag-C 3 N 4 alters the breaking patterns and spatial distribution of the polymer fragments, and reduces the graphitic growth temperature by 400 K. And the decomposition of ag-C 3 N 4 and phenolic at the fiber-matrix interface collides the fibers' surfaces to undermine the structural integrity, which induces the phase transformation from short-range to long-range order of the matrix carbon because of the templating effect (transverse) and the interlayer π-π stacking (longitudinal) of the fibers at extremely high temperature.
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RSC Advances
·
2018
·Vol. 8
·期 60
·34428-34436
·
IF 2.936
Sihui Zhan,Qianlei Hou,Yi Li,Shuanglong Ma,Pengfei Wang,Yanan Li,Haitao Wang
Visible-light-driven photocatalytic disinfection is highly desired for water treatment due to its advantages such as wide applicability and being free of disinfection byproducts. In this study, AgBr/g-C3N4 hybrid nanocomposites were evaluated as photocatalysts under visible light irradiation for water disinfection using Escherichia coli as a model pathogen. The physicochemical and photo-electrochemical properties of the photocatalyst were systematically characterized using advanced techniques including scanning electron microscopy (SEM), transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), UV-visible diffuse reflectance spectra (DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra and electron spin resonance (ESR) spectroscopy. The inactivation mechanism of E. coli was systematically investigated by monitoring the morphology change of the bacteria and analyzing the role of reactive species. The optimized AgBr/g-C3N4 hybrid photocatalyst exhibited remarkably enhanced visible-light-driven photocatalytic disinfection performance towards E. coli over that of pure g-C3N4 and AgBr under visible light, which could completely inactivate 107 cfu mL−1 E. coli in 90 min. Quenching studies indicated that h+ is the main reactive species responsible for inactivating E. coli. The mechanism study revealed a Z-scheme charge transfer mechanism between AgBr and g-C3N4. The g-C3N4 could effectively trap the photogenerated conduction band electrons of AgBr via a Z-scheme type of route, thus significantly promoting the electron–hole separation. The trapping of electrons by g-C3N4 could facilitate h+ accumulation, which accounts for the better disinfection performance of AgBr/g-C3N4 compared to AgBr and g-C3N4.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2018
·
IF 3.909
Min He,Haoran Hu,Ping Wang,Haitian Fu,Jiugang Yuan,Qiang Wang,Xuerong Fan
Silk sericin (SS) derived from silkworms has the characteristics of anti-oxidation, antibacterial, and biocompatibility, however, high solubility in water restricted its applications in biomedical fields. In the present work, SS was enzymatically graft-copolymerized with a hydrophobic vinyl monomer of methyl methacrylate (MMA), through a free radical reaction, through the combination use of hydrogen peroxide and horseradish peroxidase (HRP). Efficacy of the HRP-mediated reaction was examined by means of FTIR, SDS-PAGE, and SEC chromatogram. A bio-composite of SS- graft -polymethyl methacrylate (SS-g-PMMA) was constructed subsequently, the corresponding wettability, thermal behavior, and biocompatibility of the obtained composite were examined, respectively. The data reveal that MMA was successfully copolymerized with the reactive sites in sericin chains, resulting in a noticeable increase in the molecular weight. For the membrane of SS-g-PMMA, the surface hydrophobicity was evidently improved compared to that of the untreated, according to the determined data of water contact angle and dissolution ratio. The current work develops an eco-friendly technique for reuse of the industrial waste like sericin, and provides a novel method for preparation of the sericin-based biomaterials as well.
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CHEMISTRY-A EUROPEAN JOURNAL
·
2018
·Vol. 24
·期 59
·15930-15936
·
IF 5.16
Xue-Li Zhai,Jiang Liu,Ling-Yun Hu,Jian-Chun Bao,Ya-Qian Lan
Graphical Synergy in action . A novel polyoxometalate-decorated g-C 3 N 4 -wrapping snowflake-like CdS nanocrystal photocatalyst, by virtue of the synergistic effect stemming from the integration of the individual advantages of CdS, g-C 3 N 4 , polypyrrole, and the polyoxometalate Ni 4 (PW 9 ) 2 , displays high-performance hydrogen production activity and superior photocatalytic stability (see figure). Photocatalytic hydrogen evolution technology is recognized as a promising approach to relieving the growing energy crisis. Therefore, the development of a stable high-performance photocatalyst has long been the focus of research. In this work, quaternary composite materials involving a snowflake-like CdS nanocrystal wrapped by different amounts of polyoxometalate-decorated g-C 3 N 4 and polypyrrole (GPP@CdS) have been synthesized as photocatalysts for hydrogen production under visible-light irradiation. It has been revealed that the best composite (40 % GPP@CdS composite) exhibits hydrogen production activity of 1321 μmol, which exceeds that of CdS by a factor of more than two, and can be used in at least seven cycles with negligible loss of activity. The enhanced photocatalytic performance has been primarily attributed to the efficient synergy of CdS, g-C 3 N 4 , polypyrrole (PPy), and the polyoxometalate Ni 4 (PW 9 ) 2 . It should be noted that the introduction of PPy and g-C 3 N 4 into the title composite simultaneously promotes electron/hole pair separation and photocatalytic stability, whereas Ni 4 (PW 9 ) 2 serves as an efficient electron modulator and extra catalytic active site.
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TALANTA
·
2018
·
IF 4.244
Xiaotong Li,Xiaomin Tang,Xiaojie Chen,Baohan Qu,Lihua Lu
A novel label-free and enzyme-free detection strategy has been developed for the fluorescent detection of isocarbophos (ICP) using multi-walled carbon nanotubes (MWCNTs) and G-quadruplex as the signal transducers. In this work, the split ICP aptamer were attached to a G-quadruplex motif at their respective terminals. In the presence of ICP, the split aptamers could undergo conformational change into a sandwiched-like ternary complex, which prevent them from adsorbing to the MWCNTs due to the increased steric hindrance . As a result, the fluorescence signal of the G-quadruplex probes N-methyl mesoporphyrin IX (NMM) was enhanced significantly. In the absence of ICP, the split aptamer only existed in the form of single-stranded DNA, which could be easily adsorbed by MWCNTs and resulted in a quenched fluorescence signal of NMM. The proposed strategy could selectively and sensitively detect ICP with a detection limit of 10 nM. Furthermore, we have also demonstrated the capability of this strategy in the detection of ICP in real samples from vegetable extract, indicating the potential application of this strategy in food safety issues.
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CATALYSIS TODAY
·
2018
·
IF 4.667
Zhengyuan Jin,Jiaqi Chen,Shaolong Huang,Jiahao Wu,Qitao Zhang,Wenfei Zhang,Yu-Jia Zeng,Shuangchen Ruan,Teruhisa Ohno
A composite photocatalyst composed of carbonaceous material and g-C 3 N 4 is fabricated by a simple thermal treatment of melamine (hydrothermally treated melamine) with cellulose acetate. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and elemental analysis data reveal the formation of carbonaceous material in the composites. The photocatalytic activity was evaluated by the H 2 liberation rate from water splitting under visible-light irradiation. The optimized composite, which is prepared from the precursor of hydrothermally treated melamine with cellulose acetate, shows 35 times higher photocatalytic activity than bulk g-C 3 N 4 (melamine as the precursor) and a quantum efficiency of 1.05% (0.01 g of catalyst) under irradiation at 420 nm. The enhancement of the photocatalytic activity is ascribed to the unique electronic properties of the carbonaceous material, the enlarged specific surface area and the improved light absorption.
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APPLIED SURFACE SCIENCE
·
2018
·
IF 4.439
Lina Kong,Xintong Zhang,Changhua Wang,Jianping Xu,Xiwen Du,Lan Li
Artificial direct Z-scheme system is promising in solar-fuel production owing to their efficient charge separation and high redox capability. However, direct Z-scheme system suffers from how to construct reasonable interfacial charge transfer channel for selective charge recombination. Here we fabricate a direct Z-scheme system consisting of g-C 3 N 4 crumpled sheet with Ti 3+ -doped TiO 2 nanoparticles via polycondensation of urea with TiO 2 followed by hydrogenated treatment. UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) manifest that the hydrogenated treatment conferred Ti 3+ defect states below the conduction band minimum (CBM) of TiO 2 and improved visible light absorption of the g-C 3 N 4 /Ti 3+ -doped TiO 2 composite. The g-C 3 N 4 /Ti 3+ -doped TiO 2 exhibits remarkable photocatalytic performance for water splitting and degradation of pollutants than that of g-C 3 N 4 /TiO 2 , C 3 N 4 , and TiO 2 . The H 2 evolution rates of g-C 3 N 4 /Ti 3+ -doped TiO 2 reach up to 1938 and 287 μmol·h −1 ·g −1 under solar-light and visible-light irradiation, which is 3.4 and 2.8 times higher than that of g-C 3 N 4 /TiO 2 . The enhanced photocatalytic activity is ascribed to the Ti 3+ defects assistant formation of g-C 3 N 4 /Ti 3+ -doped TiO 2 Z-scheme photocatalyst, which results in efficient interfacial charge emigration and separation. Our work points out the critical role of defects in construction of Z-scheme pathways for charge transfer and provides possibilities for developing the other efficient photocatalysts.
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NEW JOURNAL OF CHEMISTRY
·
2018
·Vol. 42
·期 19
·15974-15984
·
IF 3.201
Wenqian Fan,Zhi Zhu,Yang Yu,Zhi Liu,Chunxiang Li,Pengwei Huo,Yue Qiu,Yongsheng Yan
In the present work, the ternary hybrid photocatalyst Fe3O4@g-C3N4/RGO is developed by a facile hydrothermal method, which shows a satisfactory degradation rate (90%) and stability in degrading tetracycline. The improvement in the photocatalytic activity of the ternary hybrid photocatalyst is attributed to the Fe3O4 nanobelt and RGO. As a center of oxidation–reduction, the Fe3O4 nanobelt can utilize electrons effectively. RGO with good conductivity is an outstanding electron transporter, which inhibits the recombination of electron–hole pairs. Moreover, the results of the ESR and the radical capture experiment prove that h+ and ˙O2− are the major active species in the tetracycline removal process. At the same time, the degradation intermediates of tetracycline and the photocatalytic mechanism is discussed in this paper in depth. The novel design concept is expected to be used in practical applications.
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CHINESE JOURNAL OF CATALYSIS
·
2018
·
IF 3.525
Hongju Han,Min Fu,Yalin Li,Wei Guan,Peng Lu,Xueli Hu
Polypyrrole-modified graphitic carbon nitride composites (PPy/g-C 3 N 4 ) are fabricated using an in-situ polymerization method to improve the visible light photocatalytic activity of g-C 3 N 4 . The PPy/g-C 3 N 4 is applied to the photocatalytic degradation of methylene blue (MB) under visible light irradiation. Various characterization techniques are employed to investigate the relationship between the structural properties and photoactivities of the as-prepared composites. Results show that the specific surface area of the PPy/g-C 3 N 4 composites increases upon assembly of the amorphous PPy nanoparticles on the g-C 3 N 4 surface. Owing to the strong conductivity, the PPy can be used as a transition channel for electrons to move onto the g-C 3 N 4 surface, thus inhibiting the recombination of photogenerated carriers of g-C 3 N 4 and improving the photocatalytic performance. The elevated light adsorption of PPy/g-C 3 N 4 composites is attributed to the strong absorption coefficient of PPy. The composite containing 0.75 wt% PPy exhibits a photocatalytic efficiency that is 3 times higher than that of g-C 3 N 4 in 2 h. Moreover, the degradation kinetics follow a pseudo-first-order model. A detailed photocatalytic mechanism is proposed with · OH and · O 2 − radicals as the main reactive species. The present work provides new insights into the mechanistic understanding of PPy in PPy/g-C 3 N 4 composites for environmental applications.
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RSC Advances
·
2018
·Vol. 8
·期 49
·28032-28040
·
IF 2.936
Xiaofeng Hu,Lixun Deng,Hua Ouyang,Huihu Wang
Graphitic carbon nitride (g-C3N4) nanosheets have been successfully immobilized on diatomite to form a g-C3N4/diatomite hybrid through a facile electrostatic adsorption method and subsequent calcination process. Electron microscopy studies confirm that the surface of the diatomite is tightly covered with g-C3N4 nanosheets. In addition, the characterization results of Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectra (XPS) verify that there is a strong interaction between the g-C3N4 and diatomite components inside the hybrids. The visible light absorption edge of the hybrids exhibits a significant redshift compared with the bare g-C3N4 nanosheets and diatomite, which leads to the improvement of visible light absorption and utilization. The photocatalytic results demonstrated that the photocatalytic performance for methyl orange and phenol degradation using the hybrids as photocatalysts has been obviously improved compared to that of g-C3N4 nanosheets, which may be ascribed to its adsorption/photocatalysis synergistic effect.
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