EUROPEAN POLYMER JOURNAL
·
2018
·
IF 3.741
Songquan Xu,Hui Zhu,Zhenjiang Li,Fulan Wei,Yu Gao,Jiaxi Xu,Haixin Wang,Jingjing Liu,Tianfo Guo,Kai Guo
H-bond donor (HBD) and base co-catalysis achieved great success in ring-opening polymerization (ROP). Parallel H-bond donor and Brønsted acid (HBD–BA) cocatalysis has been scarcely explored in ROPs. In developing the HBD–BA catalysis in to versatile toolbox for ring-opening polymerizations of wider scope and better control, tunable HBDs including boronate pinacol ester urea (BU), urea (U), and thiourea (TU) were evaluated in cooperation with trifluoroacetic acid (TFA) in HBD–BA catalytic mode. Each of the HBD–TFA co-catalyst promoted ROPs of δ-valerolactone (VL) and ε-caprolactone (CL) successfully. The catalytic performances of the HBD–TFA on the HBD part was in an order of BU > U > TU to their corresponding ROPs of VL and CL. The turnover frequencies of the catalyzed ROPs of VL and CL by BU–TFA was twice as that of TFA. The ROPs afforded homopolymers with predicted molecular weights (PVL, M n,NMR = 2.51–9.92 kg mol −1 ; PCL, M n,NMR = 2.51–11.1 kg mol −1 ) and narrow dispersities (PVL, Đ ≤ 1.16; PCL, Đ ≤ 1.18) by ratios of monomer to initiator from 20 to 100. The obtained polymers were analyzed by 1 H NMR, 13 C NMR, and MALDI-ToF MS, the results indicated the high chain-end fidelity. Chain extension experiments were conducted by a first ROP of VL/CL and second ROP of CL/VL with precise molecular weights (from 2.98 kg mol −1 to 6.15 kg mol −1 ) and narrow dispersities below 1.18. The kinetics plots showed a distinct first order relationship between ln([VL] 0 /[VL]) versus the reaction time, it indicated the controlled nature of the catalytic ROP. NMR titrations supported the proposed mechanism that HBD associated with TFA and promoted the cationic polymerization.
研究领域:
高分子化学
·
催化化学
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DOI
高影响因子
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
·
2024
·
IF 2.5
Fumeng Yin,Shan Hu,Shuwei Zhu,Shifeng Xing,Hongjun Zhu
Graphical Using mesoporous graphitic carbon nitride (mpg-C 3 N 4 ) as a metal-free heterogeneous photocatalyst was developed for thiocyanation of alkenes under visible light irradiation with oxygen as green oxidant and without any other additives. The present protocol has excellent functional group tolerance and the desired tetrasubstituted alkenyl thiocyanides were obtained in moderate to good yields. Moreover, the recyclable mpg-C 3 N 4 catalyst could be used at least 6 times without significant loss of activities. Using mesoporous graphite carbon nitride (mpg-C 3 N 4 ) as metal-free heterogeneous catalyst, the thiocyanation of ketene dithioacetals was achieved under visible light irradiation with oxygen as green oxidant and without any other additives. The present protocol has excellent functional group tolerance and the desired tetrasubstituted alkenyl thiocyanides were obtained in moderate to good yields. Moreover, the recyclable mpg-C 3 N 4 catalyst could be used at least 6 times without significant loss of activities. A series of mechanistic validation experiments indicated that the reaction involves a radical process.
研究领域:
有机化学
·
催化化学
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DOI
高影响因子
Journal of Extracellular Vesicles
·
2023
·Vol. 12
·期 9
·12364
·
IF 16
Jie He,Hengyu Li,John Mai,Yuqing Ke,Chunhui Zhai,Jiao Jiao Li,Lai Jiang,Guangxia Shen,Xianting Ding
Extracellular vesicle (EV) surface proteins, expressed by primary tumours, are important biomarkers for early cancer diagnosis. However, the detection of these EV proteins is complicated by their low abundance and interference from non-EV components in clinical samples. Herein, we present a MEmbrane-Specific Separation and two-step Cascade AmpLificatioN (MESS2CAN) strategy for direct detection of EV surface proteins within 4 h. MESS2CAN utilises novel lipid probes (long chains linked by PEG2K with biotin at one end, and DSPE at the other end) and streptavidin-coated magnetic beads, permitting a 49.6% EV recovery rate within 1 h. A dual amplification strategy with a primer exchange reaction (PER) cascaded by the Cas12a system then allows sensitive detection of the target protein at 10 EV particles per microliter. Using 4 cell lines and 90 clinical test samples, we demonstrate MESS2CAN for analysing HER2, EpCAM and EGFR expression on EVs derived from cells and patient plasma. MESS2CAN reports the desired specificity and sensitivity of EGFR (AUC = 0.98) and of HER2 (AUC = 1) for discriminating between HER2-positive breast cancer, triple-negative breast cancer and healthy donors. MESS2CAN is a pioneering method for highly sensitive in vitro EV diagnostics, applicable to clinical samples with trace amounts of EVs.
研究领域:
生物技术
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医学诊断
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癌症研究
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分子生物学
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DOI
PubMed
高影响因子
JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
·
2023
·Vol. 38
·期 4
·803-806
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IF 1.6
Ma Liang,Hu Yucheng,Zhou Zeyi,Zhu Bo,Zheng Wenjie,Zhang Rui
We reported a low-cost and easy-to-make method to effectively generate quantum dot (QD) states in 2D hBN films for quantum emissions at room temperature by utilizing silica nanospheres, in comparison with the sophisticated nanofabrication method reported in previous studies. The QDs created in 2D hBN films using silica nanospheres exhibit pronounced photon emissions with a good photo-stability in air, a narrow distribution of the emission peaks within the range of 580–620 nm, and a directional emission pattern, behaving as a single electric dipole. Our work develops the method of controllable fabrication of quantum emitters in 2D materials by using nano materials and structures.
研究领域:
量子光学
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纳米光子学
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材料科学
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二维材料
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应变工程
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高影响因子
Polymer Chemistry
·
2022
·Vol. 13
·期 10
·1437-1445
·
IF 5.364
Yongjie Zhang,Xiaopei Li,Wenqin Zhu,Pibo Liu,Juntao Ren,Shangtao Chen,Yanming Hu,Guangyuan Zhou
Post-modification of polyolefins by cutting-edge C–H activation has recently emerged as an attractive methodology for the incorporation of precise functionalities, thus expanding their applicability and creating value-added materials. In this report, chromone (CM), the core of naturally occurring molecules possessing manifold biological and pharmacological activities, was incorporated into polyethylene (PE) through the recently developed radical-mediated alkane C–H activation approach. The reaction was conducted in the presence of di-tertbutyl peroxide as the oxidant and a small amount of naphthalene as the solvent or under solvent-free conditions. The produced CM-grafted PEs (CM-PEs) exhibited intriguing antioxidative and fluorescence properties as revealed by thermogravimetric analysis (TGA) and fluorescence microscopy. Moreover, CM-PEs were successfully demonstrated to act as a polymer-bound antioxidant, a fluorescence marker for plastic sorting, and a traceable compatibilizer for the PE/polystyrene blend, revealing that CM-PE is a multi-functional material.
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高影响因子
JOURNAL OF RARE EARTHS
·
2022
·
IF 4.632
Feng Lin,Yudan Zhong,Yulong Ma,Yonggang Sun,Xiuqin Men,Yingbo Zhu
Hydrodeoxygenation (HDO) of renewable lignin-derived biomass in aqueous-phase to produce high value-added products is of great significance. However, developing new catalysts with high activity and excellent stability in an aqueous phase faces considerable challenges. Rare earth doping can effectively regulate the water exchange rate constant (WERC) value of the catalyst and play an important role in promoting the hydrolysis of ether bonds. Therefore, in this paper the bimetallic supported catalyst Ni–La 2 O 3 /H-ZSM-5 doped with rare earth metal La 2 O 3 was prepared, and used to catalyze the conversion of the lignin model compound guaiacol to cyclohexanol in the aqueous phase. The conversion of guaiacol catalyzed by 10Ni–3La 2 O 3 /H-ZSM-5 reaches 100%, and the selectivity of the product cyclohexanol is 85%. A series of characterizations illustrate that the doping of La 2 O 3 causes the electron transfer between La 2 O 3 –Ni and changes the distribution of Ni, and a strong metal carrier interaction occurs between the bimetallic Ni–La 2 O 3 and H-ZSM-5. This can effectively promote the hydrolysis of the C–O ether bond in guaiacol and significantly improve the activity of the catalyst. The possible catalytic reaction mechanism of Ni–La 2 O 3 /H-ZSM-5 catalytic conversion of guaiacol was proposed.
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高影响因子
Frontiers in Chemistry
·
2022
·
IF 5.545
Zhao Jun,Deng Nengmei
The thermal decomposition performance of an oxidizer directly determines the thrust and specific impulse properties of the solid propellant. Hexagonal boron nitride (h-BN) has the characteristics of high catalytic activity and good stability, which can improve the heat release and decomposition temperature of the oxidant, and then improve the energy performance of the propellant. In this study, a novel hybrid material TiO2 NPs/h-BN was successfully prepared by in situ growth, and it was found that when 5 wt.% TiO2 NPs/h-BN was added, the initial decomposition temperature of ammonium perchlorate (AP) decreased by 67.6°C. Due to the addition of TiO2, the gap between the h-BN layers as well as the specific surface increased, which optimized its thermocatalytic performance, and it also proposed a catalytic mechanism for the thermal decomposition process of AP.
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DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2022
·Vol. 12
·期 24
·7281-7292
·
IF 6.177
Hui Chen,Wei Li,Mingchao Zhang,Wangyang Wang,Xian-Hua Zhang,Fa Lu,Kang Cheng,Qinghong Zhang,Ye Wang
Propane dehydroaromatization (PDA) to high value-added aromatic hydrocarbons, such as benzene, toluene, and xylene (BTX), is an attractive but challenging process. The traditional Zn/H-ZSM-5 or Ga/H-ZSM-5 catalysts can offer considerable PDA performances but still suffer from low activity and poor stability because of harsh reaction conditions. Here, we report a multifunctional Pt–Zn@H-ZSM-5 catalyst that exhibits a significantly improved performance in the PDA reaction at 550 °C, with a single-pass propane conversion of 74%, aromatics selectivity of 56%, and CH4 selectivity of only 4.7%. The yield of aromatics is twice as much as those of Zn/H-ZSM-5 and Ga/H-ZSM-5 catalysts. We have demonstrated that the Pt–Zn alloy nanoparticles with an average size of 2.4 nm are uniformly confined within H-ZSM-5 crystals, providing atomic-scale proximity between metal and zeolite acid sites. This unique structure enhances not only the dehydrogenation of the propane feedstock in the initial reaction stage but also the dehydrogenation of cyclic C6+ hydrocarbons by the recombinative desorption of surface hydrogen species in the last stage while suppressing the side hydrogenolysis and hydrogen-transfer reactions. Furthermore, the Si/Al ratio of H-ZSM-5, the synergistic effect between platinum and zinc, and the location of Pt–Zn nanoparticles over composite catalysts have also been discussed. These findings suggest that via bimetallic alloying and rational arrangements of functional sites at the nanoscale, the multistep PDA reaction can be greatly intensified.
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高影响因子
Journal of Advanced Ceramics
·
2021
·Vol. 10
·期 6
·1317-1325
·
IF 6.707
Liu Zetan,Zhao Shiqiang,Yang Tian,Zhou Ji
It is possible to improve the machinability of aluminum nitride-hexagonal boron nitride (AlN-h-BN) ceramics while maintaining high strength and high thermal conductivity. The composite ceramics with 0–30 wt% BN as secondary phase were prepared by hot pressed sintering, using yttrium oxide (Y 2 O 3 ) as sintering aid. The phase composition, density, microstructure, mechanical properties, thermal conductivity, and dielectric properties were investigated. The sintering additives were favorable to purify the grain boundaries and improve densification, reacting with oxide impurities on the surface of raw material powder particles. The optimum BN content improved the flexural strength and fracture toughness of composite ceramics with 475 MPa and 4.86 MPa·m 1/2 , respectively. With increasing the amount of BN, the thermal conductivity and hardness of composites gradually decreased, but the minimum value of thermal conductivity was still 85.6 W·m −1 ·K −1 . The relative dielectric constant and dielectric loss tangent of the samples ranged from 6.8 to 8.3 and from 2.4 × 10 −3 to 6.4 × 10 −3 , respectively, in 22–26 GHz.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Yongyang Zhu,Shaoyang Shen,Liuzhang Ouyang,Jiangwen Liu,Hui Wang,Zhenguo Huang,Min Zhu
Magnesium borohydride (Mg(BH 4 ) 2 ) is widely regarded as a promising hydrogen storage material due to its high capacity; however, it is still challenging to synthesize Mg(BH 4 ) 2 with low cost. Traditionally, Mg(BH 4 ) 2 has been mainly produced using other borohydride as the starting materials via exchange reactions. Herein, we report an economical method to synthesize Mg(BH 4 ) 2 by converting B-O bonds in widely available borates or boric acid to B-H. The borates or boric acid is ball-milled with MgH 2 under ambient conditions to form Mg(BH 4 ) 2 with high yield (>80%). Mg(BH 4 ) 2 was also successfully generated by reacting low-cost Mg with boric acid. Compared with previous approaches, this method avoids expensive boron sources such as LiBH 4 , NaBH 4 , and B 2 H 6 , and does not require high pressure H 2 gas and high temperatures, and therefore significantly reduces costs. This method could be an alternative to the current Mg(BH 4 ) 2 synthesis processes.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Cuishuang Jiang,Mingyi Zhang,Guojun Dong,Tong Wei,Jing Feng,Yueming Ren,Tianzhu Luan
It is highly desirable but challenging to control nitrate contamination using photocatalytic reduction technology over non-mental catalysts. Herein, hexagonal boron nitride (h-BN), a typical non-metal catalyst, was employed to photocatalytic denitration in water with formic acid (FA) as a hole scavenger. Compared with a mental catalyst TiO 2 and a non-mental catalyst g-C 3 N 4 , h-BN obtained a more effective reduction performance with nitrate conversion of 97.16% and N 2 selectivity of 95.42%. After three cyclic use, it still presented excellent reduction activity and structure stability. In the h-BN system, the initial pH had a significant effect on the nitrate reduction performance because it determined the surface charge property of the catalyst or the dispersibility in water, and the presence of anions slightly decreased the nitrate conversion process since the competitive adsorption of NO 3 – or NO 2 – . Photocatalytic denitration over h-BN was well according with the Extended-Langmuir-Hinshelwood model. By comparing the average stoichiometric ratio of consumed FA and removed NO 3 – (i.e. experiment value) with the theoretical value, it was determined that there were additional electrons involved in the reduction reaction in addition to CO 2 •- radicals, which was also supported by the quenching experiments. Moreover, CO 2 •- radicals were mainly responsible for the conversion of NO 2 – to N 2 . Exposed B atoms on the h-BN edges behaved as the adsorption sites of nitrogen oxide anions. This study provides a proof-of-concept demonstration of non-mental photocatalyst h-BN for more effective management of nitrate contamination.
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高影响因子
DIAMOND AND RELATED MATERIALS
·
2021
·
IF 3.315
Xiaoyu Zhang,Juan Yi,Yanan Yin,Yiheng Song,Chuanxi Xiong
In recent years, with the increasing demands of portable and high-speed electronic devices, highly integrated equipment attracts people's attention more and more. However, it is a great challenge to guarantee the long-term stability of electronic products at high temperatures. Hexagon boron nitride (h-BN), which owned excellent thermal conductivity and insulation properties , was preferred for electronics. For better compatibility of inorganic fillers and silicone rubber, a biological modification by coating polydopamine (DA) on h-BN was adopted. Herein, the composites based on h-BN@PDA and silicone rubber were fabricated. Compared with h-BN/silicone rubber composites , the thermal conductivity of h-BN@PDA/silicone rubber composites increased and volume resistance of materials had been decreasing. When the amount of h-BN@PDA fillers was 30 wt%, the thermal conductivity of h-BN@PDA/silicone rubber composite increased to 0.95 W m −1 K −1 . The volume resistivity of 30 wt% h-BN@PDA/silicone rubber composite reached 2.5 × 10 11 Ω·cm, which was the lowest one among others, which still exceeded requirements of electronic materials.
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高影响因子
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