JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Junjie Xu,Wei Sun,Xiang Xiong,Hongbo Zhang,Lingkun Yang
To improve the mechanical properties and ablation resistance of Cf-reinforced ceramic-based materials, ZrC–W cermet composites (C/C–ZrC–W) were prepared in C/C preforms using slurries and low-temperature reactive melt infiltration , and their microstructure, formation mechanism, and mechanical and ablation properties were investigated. The obtained results revealed that the formation of C/C–ZrC–W composites involved the dissolution–precipitation and C diffusion processes. Owing to the precipitation of W nanoparticles in the ZrC phase and interdiffusion of W/ZrC, the fabricated C/C–ZrC–W composites exhibited superior mechanical properties with a flexural strength of 280.65 ± 12.84 MPa and fracture toughness of 13.87 ± 0.56 Mpa.m 1/2 . The formation of a Zr–W–O dense oxide layer resulted in the excellent ablation performance of the C/C–ZrC–W composites in oxyacetylene flame with a temperature of 2200 °C, and their mass ablation rate and linear ablation rate were 1.14 mg/s and 2.42 µm/s, respectively. The described method can be potentially used for preparing high-strength, high-toughness, and ablation-resistant materials at low temperatures.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2023
·
IF 6.1
Wenwen Yang,Xiaoping Zhang,Jun Zhang,Guoshuan Wang,Hailong Liang,Xinglei Zhang,Konstantin Chingin,Huanwen Chen
The positions of C═C bonds in unsaturated fatty acids (FAs) are one of the main factors determining the quality of food flavor. Herein, we developed an approach for the determination of C═C bonds of FAs by online epoxidation reaction with water dimer radical cations. The limit of detection for octenoic acid isomers was ∼9 μg/L. The positions of C═C bonds in trans-2/3-hexenoic acid, trans-2/3-octenoic acid, oleic acid, linoleic acid, and linolenic acid in black tea or olive oil samples were directly determined by the established method. These results indicate that the established method allows the rapid determination of unsaturated FAs in black tea and olive oil. The advantages of this approach include the analysis speed (∼1 min per sample), simple device, and no need for complex pretreatment. This study not only provides a strategy for the determination of C═C positions but also offers new possibilities for applications in the field of food chemistry.
研究领域:
分析化学
·
食品科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
TETRAHEDRON
·
2014
·
IF 2.817
Dazhuang Miao,Xuesong Shi,Guozhen He,Yao Tong,Zengqiang Jiang,Shiqing Han
N -(2-Chloro-phenyl)-2-halo-benzamides (halo=I/Br/Cl) as substrates were used for the one-pot synthesis of 2-arylbenzoxazole derivatives via copper-catalyzed intermolecular C–N/intramolecular C–O couplings with primary amines . This aryl amination offers clean reaction conditions and easy work-up in good yields by using CuI as catalyst, readily available 8-hydroxyquinoline as ligand, K 3 PO 4 as base, DMF as solvent.
研究领域:
有机化学
·
合成化学
✓ 已验证
DOI
高影响因子
ACS Catalysis
·
2020
·
IF 12.35
Peng Zhou,Yuguang Chao,Fan Lv,Kai Wang,Weiyu Zhang,Jinhui Zhou,Hui Chen,Liang Wang,Yiju Li,Qinghua Zhang,Lin Gu,Shaojun Guo
Photocatalytic reforming of renewable and low-cost biomass is an alternative approach to synthesize high-value-added multicarbon compounds and hydrogen. However, the difficulty in activating the methyl group of biomass and simultaneously promoting the C–C coupling makes photocatalytic reforming still a great challenge. Herein, through the first-principles simulation calculation of the energy barrier of acetone dehydrogenation and conversion over a series of noble metal single atom (Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au)-loaded TiO2 (MSA-TiO2) photocatalysts, we predict a Pt single atom-loaded TiO2 (PtSA-TiO2) photocatalyst that can enable methyl activation, CH3COCH2• radical formation, and hydrogen production most effectively from acetone, which is very significant for the synthesis of high-value-added multicarbon compounds by C–C coupling. This is well confirmed by our photocatalytic experiments, revealing that PtSA-loaded commercial P25-TiO2 exhibits the best photocatalytic activity of 3.87 mmol g–1 h–1 for the direct coproduction of high-value-added 2,5-hexanedione (HDN) and hydrogen from acetone with a selectivity of 93%, at least 13-fold higher activity than other noble metal (Ru, Rh, and Ir) single atoms or Pt nanoparticle-loaded ones. In situ attenuated total reflection infrared spectroscopy reveals that the PtSAs contribute to the effective methyl activation and simultaneously promote the formation of more intermediate CH3COCH2• radicals, which are further confirmed by in situ electron spin resonance spectroscopy.
研究领域:
化学
·
材料科学
·
催化反应
✓ 已验证
产品关联
DOI
高影响因子
Nature Ecology & Evolution
·
2023
·Vol. 7
·期 11
·1892-1902
·
IF 16.8
Ju Yun,Zhang Hong,Jiang Yanxiao,Wang Wenxin,Kan Guangfeng,Yu Kai,Wang Xiaofei,Liu Jilin,Jiang Jie
The reverse tricarboxylic acid cycle (rTCA) is a central anabolic network that uses carbon dioxide (CO 2 ) and may have provided complex carbon substrates for life before the advent of RNA or enzymes. However, non-enzymatic promotion of the rTCA cycle, in particular carbon fixation, remains challenging, even with primordial metal catalysis. Here, we report that the fixation of CO 2 by reductive carboxylation of succinate and α-ketoglutarate was achieved in aqueous microdroplets under ambient conditions without the use of catalysts. Under identical conditions, the aqueous microdroplets also facilitated the sequences in the rTCA cycle, including reduction, hydration, dehydration and retro-aldol cleavage and linked with the glyoxylate cycle. These reactions of the rTCA cycle were compatible with the aqueous microdroplets, as demonstrated with two-reaction and four-reaction sequences. A higher selectivity giving higher product yields was also observed. Our results suggest that the microdroplets provide an energetically favourable microenvironment and facilitate a non-enzymatic version of the rTCA cycle in prebiotic carbon anabolism.
研究领域:
化学
·
生物化学
·
前生物化学
·
生命起源
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
·
2022
·Vol. 194
·期 11
·4999-5016
·
IF 3.094
Ma Teng,Kong Weixi,Liu Yunting,Zhao Hao,Ouyang Yaping,Gao Jing,Zhou Liya,Jiang Yanjun
The application of immobilized enzymes in pharmaceutical and bulk chemical production has been shown to be economically viable. We demonstrate the exceptional performance of a method that immobilizes the old yellow enzyme YqjM and glucose dehydrogenase (GDH) on resin for the asymmetric hydrogenation (AH) of C = C bonds in a SpinChem reactor. When immobilized YqjM and GDH are reused 10 times, the conversion of 2-methylcyclopentenone could reach 78%. Which is because the rotor of the SpinChem reactor effectively reduces catalyst damage caused by shear force in the reaction system. When the substrate concentration is 175 mM, an 87% conversion of 2-methylcyclopentenone is obtained. The method is also observed to perform well for the AH of C = C bonds in other unsaturated carbonyl compounds with the SpinChem reactor. Thus, this method has great potential for application in the enzymatic production of chiral compounds.
研究领域:
生物催化
·
酶工程
·
药物化学
·
有机合成
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2022
·Vol. 10
·期 20
·11268-11276
·
IF 14.511
Jiabao Guo,Yizhuo Zhao,Peng Wang,Yang Song,Yifei Shao,Li Zhu,Xiaoquan Yao
Catalytic selective cleavage reaction of the C(sp3)–C(sp3) bond has received little attention, despite its importance in organic synthesis and biochemistry. Herein, a novel copper loaded nitrogen-rich mesoporous carbon nitride material was designed and synthesized, and utilized as a highly efficient photocatalyst for the inert C–C bond cleavage of amines under blue light irradiation. With oxygen as a benign oxidant, good to excellent yields were achieved for various functionalized amines at room temperature, even including sluggish aliphatic amines. The method may provide a cost-effective and environmentally friendly alternative for the direct oxidative cleavage of amines.
研究领域:
有机合成
·
光催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2023
·Vol. 58
·期 22
·9196-9209
·
IF 4.5
Tang Zhen-xiao,Yi Mao-zhong,Zhou Yuan-ming,Liu Rui-zhi,Peng Ke
A three-dimensional orthogonal woven C/C-SiC composite was successfully prepared by high-solid-loading slurry impregnation combined with precursor infiltration and pyrolysis. The microstructure, mechanical properties and ablation behavior of the C/C-SiC composite were investigated. The slurry impregnation and the precursor infiltration and pyrolysis acted as fast filling and supplementary densification, respectively. Based on a three-dimensional orthogonal woven C/C preform, the C/C-SiC composite had excellent mechanical properties with bending strength and fracture toughness of 364.46 and 22.86 MPa·m 1/2 . The mass and linear ablation rates of the C/C-SiC composite were 3.21 mg/s and 4.93 μm/s, respectively, after ablation under an oxyacetylene flame for 300 s. The good ablation performance was attributed to the passive oxidation of SiC at high temperature and high oxygen partial pressure, and the pitting caused by SiO 2 accelerated the failure of carbon fibers.
研究领域:
材料科学
·
复合材料工程
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高温结构材料
·
航天热防护材料
✓ 已验证
DOI
高影响因子
Applied Materials Today
·
2023
·
IF 8.3
Guiyang Yu,Ke Gong,Lan Hu,Chuanwang Xing,Yujia Hu,Debao Wang,Xiyou Li
The development of mild and environmental method for direct transformation of aromatic alcohol into hydrobenzoin via controlled C‒C coupling is a highly attractive but challenging goal. In this paper, a P-doped g-C 3 N 4 photocatalyst with NiS nanoparticles modification is first reported to apply the visible-light-driven C‒C coupling of aromatic alcohol into hydrobenzoin, as well as integrating with the production of clean H 2 fuel. The synergistic effect of doped P atoms and formed type-II heterojunction between PCN and NiS improves the light absorption ability of g-C 3 N 4 and greatly suppresses the charge recombination. Optimized 2.0% NiS/PCN composite achieves the complete conversion of aromatic alcohol within 6 h reaction time, as far as we known, which is the highest efficiency so far for aromatic alcohol conversion via photocatalytic strategy. Hydrobenzoin is controllably formed with 68% selectivity, together with a highly-efficient H 2 production rate of 994.8 μmol·g −1 ·h −1 . In-situ EPR studies reveal a preferential activation of C‒H bond than O‒H bond in aromatic alcohol by photoexcited holes, forming C 6 H 5 ĊH 2 OH radicals for subsequent coupling. The residual protons interact with photoexcited electrons to generate H 2 . Our study not only offers an efficient g-C 3 N 4 -based photocatalyst for the synthesis of hydrobenzoin under mild conditions, but also opens up a new avenue for manipulating the activation of C‒H or O‒H bonds for high selectivity of hydrobenzoin product.
研究领域:
化学
·
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2015
·Vol. 3
·期 46
·23149-23161
·
IF 7.443
Xiaopeng Xu,Kui Feng,Kai Li,Qiang Peng
A series of new two-dimensional copolymers, PBDTT-TABT, PBDTT-TANT and PBDTT-TSNT, with conjugated benzodiathiazole (BT) or naphthobisthiadiazole (NT) side chains were successfully synthesized and characterized for high performance polymer solar cells (PSCs). The NT unit showed a stronger electron-withdrawing ability and a larger conjugation than the BT unit, which induced a stronger ICT process between the benzodithiophene (BDT)-thiophene (T) backbone and the conjugated side chain for NT containing copolymers. As a result, PBDTT-TANT and PBDTT-TSNT showed lower-lying bandgaps and more red-shifted absorption than PBDTT-TABT. The alkylthio modification effect of conjugated side chains was also investigated in this work. This effect showed a positive role in lowering the HOMO energy level, and a negative role in elevating carrier mobility and molecular stacking properties in our two-dimensional polymeric systems. Bulk heterojunction (BHJ) PSCs were fabricated using these copolymers as the donor materials to evaluate their photovoltaic properties. The PBDTT-TABT, PBDTT-TANT and PBDTT-TSNT devices exhibited PCEs of 4.60%, 5.65% and 4.01%, respectively. In spite of the Voc values, the highest Jsc, FF and PCE were achieved for the PBDTT-TANT device, which was attributed to its red-shifted absorption, improved carrier mobility and well-defined phase separation. It is interesting that the Jscs, FFs and PCEs of all these devices were elevated significantly when made using the solvent vapor annealing (SVA) method. The THF–SVA process would provide a driving force to facilitate the formation of a much more well-defined surface morphology, resulting in the enhanced Jsc and FF values. The PBDTT-TANT device showed the highest PCE of 8.04%, which is the top efficiency for this type of two-dimensional copolymer with donor (D)–donor (D) polymer backbones and donor (D)–acceptor (A) conjugated side chains. Our design strategy would give an instructive guide to developing high performance two-dimensional polymer donors to be used in organic photovoltaic applications.
研究领域:
材料科学
·
有机光电子学
✓ 已验证
DOI
高影响因子
Advanced Powder Materials
·
2025
·
IF 24.9
Yang Li,Bin Sun,Ying Li,Chong Zhang,Pu-Jun Jin,Xin Wang,Bao Yu Xia,Yu Chen,Xuan Ai
The large-scale implementation of direct ethylene glycol fuel cells (DEGFCs) relies on the design of catalysts that possess exceptional activity, durability, and efficient C–C bond breaking ability. However, Pt and Pd-based nanomaterials continue to face challenges of low selectivity and slow reaction kinetics in driving the complete oxidation of ethylene glycol to CO 2 . In this work, a facile one-pot reduction method is reported for controllable synthesis of PtBi nanodendrites (PtBi-NDs) composed of ultrathin bimetallene subunits. In alkaline media, the composition optimized PtBi-NDs demonstrate outstanding activity and strong resistance to CO poisoning during the ethylene glycol oxidation reaction (EGOR). The PtBi-NDs show 5.8-fold higher mass activity, enhanced stability, and superior C1 selectivity relative to commercial Pt nanoparticles (Pt c-NCs). Most strikingly, PtBi-NDs deliver a higher power density (8.3 mW cm –2 ) than Pt c-NCs in DEGFCs. The theoretical analysis and experimental measurements explain that the introduction of Bi element into Pt induces d–p orbital hybridization and promotes electron transfer from Bi to Pt, thereby facilitating C–C bond cleavage and boosting EGOR kinetics. This work establishes an effective strategy for constructing Pt-based ultrathin bimetallenes and offers fundamental insights into boosting EGOR performance via d-p orbital hybridization.
研究领域:
电催化
·
纳米材料化学
·
能源化学
·
物理化学
·
燃料电池
·
表面科学
✓ 已验证
产品关联
DOI
高影响因子
ORGANOMETALLICS
·
2020
·
IF 3.804
Liangwei Zhang,Long Liu,Tianzeng Huang,Qizhi Dong,Tieqiao Chen
A palladium-catalyzed cyclobutanation of aryl sulfonates with strained alkenes has been developed. The methodology is featured to achieve the cleavage of both C–O and C–H bonds of phenol derivatives in one pot. Under the reaction conditions, in addition to reactive triflates, the relatively inactive tosylates and mesylates can also be transformed into the corresponding benzocyclobutanes in high yields. This reaction can be carried out in gram-scale experiments with a low loading of the palladium catalyst and is applicable to the cyclobutanative modification of bioactive molecules, highlighting its synthetic value in organic synthesis.
研究领域:
有机化学
·
催化化学
·
合成化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）