CEMENT AND CONCRETE RESEARCH
·
2022
·
IF 11.958
Fang Sun,Xueyu Pang,Shiho Kawashima,Guodong Cheng,Shenglai Guo,Yuhuan Bu
In order to study the abnormal viscosity evolution behavior of oil well cement slurries containing tartaric acid, the influence of tartaric acid on the early-age hydration of oil well cement at high temperatures was investigated by isothermal calorimetry (IC), thermogravimetric analysis (TGA) and quantitative XRD (QXRD) analysis in the temperature range of 60 °C to 89 °C. Results show that, a high dosage of tartaric acid can fundamentally change the typical shape of the cement hydration heat flow curve - two additional exothermic peaks associated with aluminate phase hydration (C 3 A and C 4 AF) appear before the main hydration peak. The unsynchronized hydration of the aluminate phases and the silicate phases was found to be the cause of premature setting. Additionally, long-term curing study (up to 28 d) showed that increasing the dosage of tartaric acid decreased the ultimate hydration extent of C 2 S while it increased the ultimate hydration extent of C 4 AF.
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高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Qiao Li,Yang Huang,Zhong Pan,Jiancong Ni,Weiqiang Yang,Jianhua Chen,Ying Zhang,Jianmin Li
Novel hollow C, N-TiO 2 @C surface molecularly imprinted microspheres (HCNTC-SMIPs) with hydrophilicity, reusability, and selectivity were synthesized. The core–shell hollow structure yields large specific surface areas, high surface-to-volume ratios and effective diffusion rate on both inner and outer exposed surfaces. The C, N-TiO 2 shell possesses high photo-catalytic decomposition capacity toward the specific pollutants. Moreover, TiO 2 acts not only as a photocatalyst but also as a double cross-linker agent of molecularly imprinted to significantly reduce the molar ratio of formaldehyde. The hydrophilic surface imprinted layer provides the recognition sites and specific pore structures. The results showed that HCNTC-SMIPs possessed a high specific surface area of 305.10 m 2 g −1 and a good visible light harvesting property with a bandgap of 1.67 eV. This could efficiently suppress the photoelectron-hole recombination, and thereby heightening the photocatalytic degradation of sulfadiazine (SDZ). The photodegradation efficiency of HCNTC-SMIPs can reach 99.25 % within 140 min and 90.00 % after 6 cycles. The HCNTC-SMIPs had a higher kinetic constant (0.01815 min −1 ) than those of HCNTC (0.00964 min −1 ) and TiO 2 (0.00548 min −1 ). HCNTC-SMIPs can achieve targeted and efficient SDZ removal, as well as in-situ regeneration. The possible degradation pathways of SDZ primarily includes smiles-type rearrangement, SO 2 extrusion, ring hydroxylation, direct oxidation and S N bond cleavage processes based on LC-MS analysis.
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ANALYST
·
2022
·Vol. 147
·期 7
·1341-1347
·
IF 5.227
Chen-Chen Jiang,Xiao-Chong Li,Jian-Ang Fan,Jia-Ying Fu,Xu-Nan Huang-Fu,Jia-Jie Li,Ju-Fang Zheng,Xiao-Shun Zhou,Ya-Hao Wang
The electroreductive cleavage of carbon–halogen bonds has attracted increasing attention in both electrosynthesis and pollution remediation. Herein, by employing the in situ electrochemical shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) technique, we have successfully investigated the electroreductive dehalogenation process of aryl halides with the thiol group on a smooth Au electrode in aqueous solution at different pH values. The obtained potential-dependent Raman spectra directly reveal a mixture of the reduction products 4,4′-biphenyldithiol (BPDT) and thiophenol (TP). The conversion ratios of the C–Cl and C–Br bonds at pH = 7 are 37% and 55%, respectively. Furthermore, quantitative analysis of the intensity variations of ν(C–Cl), ν(C–Br) and aromatic ν(CC) stretching modes suggests electroreductive dehalogenation via both direct electron transfer reduction and electrocatalytic hydrodehalogenation. Molecular evidence for the C–C cross coupling process through TP reaction with benzene free radical intermediates is found at negative potentials, which leads to the increasing selectivity of biphenyl products.
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高影响因子
Nature Energy
·
2022
·Vol. 7
·期 2
·153-162
·
IF 67.439
Tang Hongying,Geng Kang,Wu Lei,Liu Junjie,Chen Zhiquan,You Wei,Yan Feng,Guiver Michael D.,Li Nanwen
Conventional proton exchange membrane fuel cells (PEMFCs) operate within narrow temperature ranges. Typically, they are run at either 80‒90 °C using fully humidified perfluorosulfonic acid membranes, or at 140‒180 °C using non-humidified phosphoric acid (PA)-doped membranes, to avoid water condensation-induced PA leaching. However, the ability to function over a broader range of temperature and humidity could simplify heat and water management, thus reducing costs. Here we present PA-doped intrinsically ultramicroporous membranes constructed from rigid, high free volume, Tröger’s base-derived polymers, which allow operation from −20 to 200 °C. Membranes with an average ultramicropore radius of 3.3 Å show a syphoning effect that allows high retention of PA even under highly humidified conditions and present more than three orders of magnitude higher proton conductivity retention than conventional dense PA-doped polybenzimidazole membranes. The resulting PA-doped PEMFCs display 95% peak power density retention after 150 start-up/shut-down cycles at 15 °C and can accomplish over 100 cycles, even at −20 °C.
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高影响因子
CHROMATOGRAPHIA
·
2023
·Vol. 86
·期 6
·469-482
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IF 1.7
Ji Wenquan,Wang Yongjian,Zhang Hongfeng,Zhao Jin,Li Qinran,Deng Qiliang,Sun Donglan,Liu Tianjun
A kind of epitope surface imprinted particles was synthesized to selectively recognize cytochrome c (Cyt c) by a novel strategy assisted with γ-cyclodextrin (γ-CD) by host-guest interaction. C-terminal epitope nonapeptide of Cyt c was chosen as the template. γ-CD was immobilized on the surface of the silica as an encapsulated molecule to capture the template and improve the corresponding spatial orientation by the host-guest interaction for the peptide and target protein recognition. After γ-CD and epitope modified, the surface imprinted polymer assisted with the host-guest interaction was synthesized via monomers and cross-linkers by radical polymerization strategy. After the peptide removal, the epitope surface imprinted particles were obtained. The performance of Cyt c recognition in bovine serum sample by the imprinted polymers was calculated by HPLC. The modified imprinted polymers prepared achieved the best binding capability of 2.89 mg g −1 AE-9 with the IF = 4.07 and 37.58 mg g −1 Cyt c with the IF = 3.38, and it also realized an efficiency and selectivity protein recognition. Additionally, the imprinted particles assisting by γ-CD have good reusability with 89.89% of the original after five sorption-elution cycles and a better recognized ability (IF = 3.38) than those without γ-CD assisting (IF = 1.44). These results indicated that this epitope imprinted method assisted with the host-guest recognition interaction by γ-CD exhibited well specific recognition abilities towards the target protein Cyt c and potential application for Cyt c recognition in biological sample. Graphical Abstract
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高影响因子
PLANT JOURNAL
·
2021
·Vol. 106
·期 2
·351-365
·
IF 6.486
Cheng-Yong Feng,Shan-Shan Li,Goro Taguchi,Qian Wu,Dan-Dan Yin,Zhao-Yu Gu,Jie Wu,Wen-Zhong Xu,Cheng Liu,Liang-Sheng Wang
SUMMARY Lotus plumule, the embryo of the seed of the sacred lotus ( Nelumbo nucifera ), contains a high accumulation of secondary metabolites including flavonoids and possesses important pharmaceutical value. Flavonoid C -glycosides, which accumulate exclusively in lotus plumule, have attracted considerable attention in recent decades due to their unique chemical structure and special bioactivities. As well as mono- C -glycosides, lotus plumule also accumulates various kinds of di- C -glycosides by mechanisms which are as yet unclear. In this study we identified two C -glycosyltransferase (CGT) genes by mining sacred lotus genome data and provide in vitro and in planta evidence that these two enzymes (NnCGT1 and NnCGT2, also designated as UGT708N1 and UGT708N2, respectively) exhibit CGT activity. Recombinant UGT708N1 and UGT708N2 can C -glycosylate 2-hydroxyflavanones and 2-hydroxynaringenin C -glucoside, forming flavone mono- C -glycosides and di- C -glycosides, respectively, after dehydration. In addition, the above reactions were successfully catalysed by cell-free extracts from tobacco leaves transiently expressing NnCGT1 or NnCGT2. Finally, enzyme assays using cell-free extracts of lotus plumule suggested that flavone di- C -glycosides (vicenin-1, vicenin-3, schaftoside and isoschaftoside) are biosynthesized through sequentially C -glucosylating and C -arabinosylating/ C -xylosylating 2-hydroxynaringenin. Taken together, our results provide novel insights into the biosynthesis of flavonoid di- C -glycosides by proposing a new biosynthetic pathway for flavone C -glycosides in N. nucifera and identifying a novel uridine diphosphate-glycosyltransferase (UGT708N2) that specifically catalyses the second glycsosylation, C -arabinosylating and C -xylosylating 2-hydroxynaringenin C -glucoside.
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高影响因子
ChemElectroChem
·
2020
·Vol. 7
·期 21
·4423-4430
·
IF 4.154
Chao Yuan,Dujiang Lu,Yongling An,Xiufang Bian
Graphical Grind and coat : A novel nanocomposite of amorphous carbon-coated Si nanosphere and ZIF-67 derived hollow porous cobalt sulfide/carbon polyhedron is fabricated by a simple grinding process. ZIF-67 derived Co 9 S 8 /C can serve as a buffer to alleviate the volume expansion of Si. The vast conductive carbon layer originated from Co 9 S 8 /C and Si@C plays a key role in facilitating the electron transfer and lithium ion transport kinetics. Si@C−Co 9 S 8 /C anodes deliver improved electrochemical performance. Silicon (Si) is regarded as one of the most promising anode materials for lithium-ion batteries (LIBs) due to its high capacity and low working voltage. However, dramatic volume expansion and inferior electrical conductivity greatly impede the commercial use of Si anodes. Herein, we design and synthesize a novel nanocomposite of Si nanosphere coated by carbon (Si@C) and hollow porous Co 9 S 8 /C polyhedron (Si@C−Co 9 S 8 /C). The hollow porous Co 9 S 8 /C derived from Co-based zeolitic imidazolate framework can serve as a buffering matrix to accommodate the volume expansion of Si, which is beneficial to improve the cycle performance. The vast conductive carbon layer originated from Co 9 S 8 /C and Si@C plays a key role in accelerating the electron transfer and lithium ion transport kinetics, which can significantly enhance the rate performance. As a result, the Si@C−Co 9 S 8 /C anodes deliver stable cycle performance with a reversible capacity of 1399 mA h g −1 after 200 cycles at 100 mA g −1 , improved rate performance and high Coulombic efficiency. This simple route sheds light on designing Si-based composites for LIBs anodes.
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高影响因子
SURFACE & COATINGS TECHNOLOGY
·
2020
·
IF 3.784
Dongmei Pu,Pengju Chen,Peng Xiao,Zhuan Li,Pingyi Deng,Liang Pang,Jinwei Li,Yang Li
A dense and uniform c -AlPO 4 and SiC whisker co-modified mullite coating was successfully prepared on SiC-coated C/SiC composites with a thickness of about 70 μm by hydrothermal electrophoretic deposition . The thermal cycling performance of the coating samples was evaluated by thermally cycling between 1773 K and room temperature in a corundum tube furnace. Results show that the addition of SiC whisker (SiC w -mullite coating) significantly improved the thermal cycling resistance of single mullite outer layer on account of the toughening mechanism of SiC whiskers, such as whisker bridging and crack deflection. Then, the addition of c -AlPO 4 ( c -AlPO 4 -SiC w -mullite coating, termed ASM coating) further improved the thermal cycling resistance on account of the healing and bonding performances of c -AlPO 4 at high temperature. After 40 thermal cycles, the weight loss of ASM coating on SiC-coated C/SiC composites was 4.5% compared to 5.24% for the SiC w -mullite coating. The retention rate of compressive strength of ASM coating on SiC-coated C/SiC matrix was 80.66% compared to 73.65% for the SiC w -mullite coating.
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高影响因子
Journal of Advanced Ceramics
·
2020
·Vol. 9
·期 3
·320-328
·
IF 2.889
Yu Zhaoju,Yang Yujing,Mao Kangwei,Feng Yao,Wen Qingbo,Riedel Ralf
A novel single-source-precursor for SiC-TaC-C nanocomposites was successfully synthesized by the chemical reaction between a polycarbosilane (allylhydridopolycarbosilane, AHPCS) and tantalum(V) chloride (TaCl 5 ), which was confirmed by Fourier transform infrared spectra (FTIR) measurement. After pyrolysis of the resultant single-source-precursors at 900 °C, amorphous ceramic powders were obtained. The 900 °C ceramics were annealed at different temperatures in the range of 1200–1600 °C to gain SiC-TaC-C nanocomposites. The phase evolution of ceramic nanocomposites was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results indicate that the TaC starts to crystallize at lower temperature than the β-SiC. It is particularly worth pointing out that the unique core-shell structured TaC@C nanoparticles were in-situ formed and homogeneously distributed in the ceramic matrix after annealing at 1400 °C. Even at a high temperature of 1600 °C, the grain sizes of β-SiC and TaC are smaller than 30 nm, fulfilling the definition of nanocomposites. The present study related to SiC-TaC-C nanocomposites paves a new road for enriching ultra-high temperature ceramic family suitable for structural/functional applications in harsh environment.
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高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Chen Zeng,Mingyu Zhang,Hanwei He,Xiaodong Wang,Kai Tong,Yafeng Wang,Ping Xu,Lei Zheng,Guang Zeng,Zhean Su,Qizhong Huang
Sol-gel is a promising technology to prepare the C/C–ZrC–SiC composites. However, carbon fiber erosion caused by carbothermal reduction severely degrades properties of the composites. At present study, the addition order of carbon source during sol-gel process was optimized to improve the microstructure, mechanical property and ablation resistance of the composites. Results show that adding phenolic resin before gelation combined with deposited pyrocarbon interlayer around the carbon fibers can greatly alleviate the degradation of the C/C–ZrC–SiC composites by reducing the carbon fiber erosion. The composites thus prepared delivered the flexural strength , mass and linear ablation rates are 162.58 MPa, 0.147 mg/(cm 2 ⋅s) and 0.0098 mm/s, respectively, which are 449% higher, 9.26% lower and 38.36% lower than those of the counterpart that added phenolic resin after gelation. The excellent performance is attributed to little erosion of the carbon fibers and the dense matrix of ZrC–SiC ceramics obtained from adding carbon source before gelation during the sol-gel process.
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CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Dongmei Pu,Pengju Chen,Peng Xiao,Zhuan Li,Zeyan Liu,Yang Li
An oxidation protective c -AlPO 4 and SiC whisker co-modified mullite coating ( c -AlPO 4 -SiC w -mullite) on SiC coated C/SiC composites were manufactured by hydrothermal electrophoretic deposition accompanied by magnetic stirring. Phase composition of c -AlPO 4 -SiC w -mullite coatings on SiC coated C/SiC composites with different deposition time was detected by X-ray Diffraction (XRD), element distribution and microstructure were investigated by electron probe microanalysis (EPMA) and scanning electron microscopy (SEM). Results show that a crack-free, dense and homogeneous coating was prepared by hydrothermal electrophoretic deposition method. The thickness, homogeneity and antioxidant properties of c -AlPO 4 -SiC w -mullite coating were improved with the extension of deposition time from 10 min to 30 min. The coating manufactured after deposition of 30 min showed smoothest surface and highest density, which can effectively protect C/SiC composites from oxidation for 160 h at 1773 K in air with a weight loss of 10.02 mg cm −2 . Microstructural characterization after oxidation indicated that the failure of the c -AlPO 4 -SiC w -mullite coating was due to the consecutive formation of penetrative micro-cracks and micro-holes.
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高影响因子
Chemistry-An Asian Journal
·
2018
·Vol. 14
·期 3
·416-421
·
IF 3.692
Qian Wang,Wei Sun,Tianying Xie,Limei Cao,Ji Yang
Graphical Carbon-coated catalysts : Octahedral Pt/ZrO 2 @C, prepared by direct carbonization of the precursor UiO-66-NH 2 (a zirconium-based metal–organic framework), exhibits improved catalytic activity for selective catalytic reduction with H 2 at ambient temperature, compared with that of other platinum-based catalysts with porous materials as supports (see figure). Selective catalytic reduction (SCR) of NO x with H 2 as a reductant is the most promising denitration technology at low temperature. Achieving the conversion of NO x into N 2 at ambient temperature not only prolongs the service life of the catalyst, but also provides more freedom for the arrangement of denitration units throughout the flue gas treatment equipment. However, the development of highly efficient, stable, and environmentally benign supported platinum-based catalysts for H 2 -SCR at ambient temperature is still a major challenge. Herein, a 0.5 wt % Pt/ZrO 2 @C catalyst, which was composed of carbon-coated octahedral ZrO 2 with highly dispersed Pt particles, was prepared by using a new stabilization strategy based on UiO-66-NH 2 (a zirconium metal–organic framework) as a template. The catalytic performance of this Pt/ZrO 2 @C in H 2 -SCR was tested and confirmed to achieve near 100 % NO x conversion at 90 °C. Also, 70 % N 2 selectivity of the catalyst was achieved. The morphology, structure, and porous properties of the as-synthesized nanocomposites were characterized by using data obtained from field-emission SEM, TEM, XRD, Raman spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and N 2 adsorption–desorption isotherms. The results show that residual carbon formed by pyrolysis treatment is coated on octahedral ZrO 2 , and effectively prevents the agglomeration of platinum particles on the surface.
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高影响因子
危险品化学品经营许可证（带存储）