CONSTRUCTION AND BUILDING MATERIALS
·
2017
·
IF 3.169
Jinfeng Sun,Hu Shi,Binbin Qian,Zhiqiang Xu,Weifeng Li,Xiaodong Shen
This work investigates the influence of synthetic C-S-H/polycarboxylate(PCE) nanocomposites (CPNs) on the hydration and properties of hydrated cement pastes. HPEG-PCE copolymers exhibiting side chain length of 45 ethylene oxide (EO) units was utilized to synthesize CPNs by precipitating C-S-H from Na 2 SiO 3 and Ca(NO 3 ) 2 in the PCE solution. A Box-Behnken Design (BBD) for the Response Surface Methodology (RSM) was employed to statistically optimize the sizes of the resultant. The prepared CPNs were characterized by particle size distribution (PSD), X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR) and thermo gravimetric/derivative thermo gravimetric (TG/DTG) analyses. The influence of CPNs on the hydration properties of cement were assessed and discussed in terms of hydration kinetics, mechanical properties, phase composition and pore structure analysis. The experimental results showed that the optimum synthetic parameters, an experimental temperature of 30.1 °C, reactant flow velocity of 0.63 ml/min and initial volume of PCE solution of 28.5 ml, produced CPNs with a minimum size of 329.12 nm. It was demonstrated that PCE polymers were either grafted on the surface or partially intercalated in the interlayer regions of C-S-H, and their introduction also increased the distance between C-S-H interlayers. Cement hydration was significantly promoted as a result of an increased heat release, even at low CPNs content. The early compressive strength of the mortar significantly improved with increasing CPNs content due to the accelerated cement hydration of the CPNs: the 0.6 wt.% CPNs content improved the compressive strength by 18.97%. Moreover, the inclusion of CPNs is advantageous for pore modification: the total porosity decreased by 25.77% after 3 days. Finally, phase composition analysis confirmed that no new crystalline phase was produced upon CPNs addition.
研究领域:
建筑材料科学
·
化学工程
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产品关联
DOI
高影响因子
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
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2022
·
IF 6.76
Junfeng Yang,Yuyang Wu,Yanhui Dong,Hao Cui,Chenyang Shi,Hang Sun,Shengyan Yin
Herein, a ternary Bi@H-TiO 2 /B-C 3 N 4 type II heterostructure is successfully designed and prepared via metal Bi as cocatalyst for photocatalytic H 2 generation. As expected, under λ > 300 nm light, the highest photocatalytic hydrogen production rate (HPR) of Bi@H-TiO 2 /B-C 3 N 4 is up to 223.08 μmol g −1 h −1 . Excitingly, under visible light (λ > 400 nm), the highest HPR of Bi@H-TiO 2 /B-C 3 N 4 is increased to 18.84 μmol g −1 h −1 , which is about 67.3 times, 37.7 times and 6.8 times as high as that of H-TiO 2 , B-C 3 N 4 and H-TiO 2 /B-C 3 N 4 under the same conditions, respectively. Moreover, the electrochemical impedance spectroscopy and transient photocurrent tests manifest that the interface resistance of Bi@H-TiO 2 /B-C 3 N 4 composite decreases and the photocurrent density increases after loading metal Bi. These results indicate that loading metal Bi as cocatalyst (providing more electron trapping sites) is beneficial to improve photocatalytic activity in the type II heterostructure composite. And the electron transfer directions (B-C 3 N 4 → H-TiO 2 → Bi or B-C 3 N 4 → Bi) are proved by ultraviolet photoelectron spectroscopy test. Therefore, the Bi@H-TiO 2 /B-C 3 N 4 photocatalyst with strong visible light absorption is expected to be a promising candidate in photocatalytic fields under visible light.
研究领域:
材料科学
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能源化学
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光催化
✓ 已验证
产品关联
DOI
高影响因子
Frontiers in Chemistry
·
2018
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IF 4.155
She Houde,Li Liangshan,Zhou Hua,Wang Lei,Huang Jingwei,Wang Qizhao
Selective activation of saturated C–H bond in hydrocarbons to produce high-value-added chemicals is of great significance for chemical synthesis and transformation. Herein, we present a facile procedure to achieve Ni-doped CdS nanoparticles with mixed (cubic and hexagonal) phases, as well as its application to the photocatalytic activation of saturated primary C–H bond of toluene and its derivatives. The photocatalytic oxidation rate of toluene into benzaldehyde of formation reached up to 216.7 μmolh−1g−1 under visible light irradiation. The excellent photocatalytic performance of Ni(II)-doped CdS [Ni(II)/CdS] can be attributed to its unique structural assembly with cubic and hexagonal phases and also the addition of Ni ions, together taking effect in promoting the separation of photogenerated charge carriers. The possible reaction mechanism for the photocatalytic selective oxidation is illustrated in this work. The band width of the as-prepared mixed phase CdS is reduced, which can effectively expand the response range and improve photocatalytic performance.
研究领域:
化学合成
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材料科学
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光催化反应
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENERGY & FUELS
·
2022
·
IF 4.654
Xianqiang Huang,Yanan Cui,Gang Liu,Haitao Wang,Junyu Ren,Yalin Zhang,Guodong Shen,Lingling Lv,Huai-Wei Wang,Yi-Fa Chen
With the arising concern of environmental problems, the removal of polycyclic aromatic hydrocarbons or sulfides in fuel oils is an indispensable process to achieve a clean energy source. At present, direct catalytic oxidation of benzyl C–H bonds of polycyclic aromatic hydrocarbons and sulfides to corresponding carbonyl compounds is very attractive, yet their simultaneous oxidation using a single economical-friendly catalyst is not yet well established. Here, three imidazole-decorated copper polyoxomolybdate frameworks (Im-Cu-PMoFs) are successfully synthesized by tuning different imidazole derivatives. These Im-Cu-PMoFs can serve as effective heterogeneous catalysts for the one-pot oxidation of benzylic hydrocarbons and sulfides to produce carbonyl compounds. Specifically, Im-Cu-PMoFs-3 as a single component catalyst exhibits high activity and prominent selectivity (conversion up to 99% and selectivity up to 99%) in the one-pot reaction. In addition, the possible reaction pathway and active sites are supported by sufficient characterizations and DFT calculations, which reveal the synergistic effect of Mo(VI) and Cu(II) centers in the one-pot catalysis reaction. These dual function-validated frameworks hold much promise in the exploration of novel catalysts for applications like continuous catalytic or flow bed reaction.
研究领域:
化学
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Cell Reports Physical Science
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2021
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IF 0
Ming Shi,Hongpeng Zhou,Wenming Tian,Bin Yang,Songqiu Yang,Keli Han,Rengui Li,Can Li
Although bismuth (Bi)-based halide perovskites have attracted profound attention in photocatalysis, the undesirable photophysical properties are not well modulated, and the effect of surface structure on adsorption and activation of reactant molecules is still unclear. Here, we report the structural design, via precise incorporation of antimony (Sb) atoms into the host lattice of Cs 3 Bi 2 Br 9 , of a series of B-site bimetallic perovskites (Cs 3 Sb x Bi 2-x Br 9 , 0 ≤ x ≤ 2) with tunable band structures. The incorporation of Sb dramatically enhances the separation and transfer of photogenerated charges and prolongs their lifetimes. Considering these advantages, Cs 3 SbBiBr 9 exhibits significantly enhanced photocatalytic activities in challenging benzylic C–H activation while maintaining a high selectivity of 96%. Theoretical calculations reveal that the introduction of Sb breaks the symmetry of the local structure and leads to asymmetric charge distribution that not only increases the adsorption capacity for methylbenzene but also reduces the energy barriers for C–H bond activation.
研究领域:
材料科学
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光化学
✓ 已验证
DOI
Marine Drugs
·
2021
·Vol. 19
·期 2
·79
·
IF 5.118
Hengju Ge,Di Zhang,Muran Shi,Xiaoyuan Lian,Zhizhen Zhang
In 2019, streptoglutarimide H (SGH) was characterized as a new glutarimide from the secondary metabolites produced by a marine-derived actinomyceteStreptomycessp. ZZ741 and shown to have in vitro antiglioma activity. However, the antiproliferative activity and potential mechanism of SGH against lung cancer cells have not yet been characterized. This study demonstrated that SGH significantly inhibited the proliferation of different lung cancer cells. In terms of mechanism of action, SGH downregulated cell cycle- and nucleotide synthesis-related proteins to block cell cycle at G0/G1 phase, reduced the expression levels of glycolytic metabolic enzymes to inhibit glycolysis, and downregulated the important cancer transcription factor c-Myc and the therapeutic target deubiquitinase USP28. Potent anticancer activity and multiple mechanisms indicated SGH to be a novel antitumor compound against lung cancer cells.Keywords:Streptoglutarimide H;lung cancer cells;antiproliferative activity;cell cycle block;glycolysis;USP28;c-Myc
研究领域:
肿瘤学
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药理学
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海洋生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
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2023
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IF 3.6
Jianyu Dong,Shaofeng Wu,Furong Geng,Yani Yan,Long Liu,Yongbo Zhou
A metal-free and selective oxidative methyl C–H functionalization of BHT with aniline compounds has been developed. This innovative method enables the facile and efficient synthesis of a diverse array of BHT-functionalized N-containing skeletons, including arylamines, benzoxazoles, benzothiazoles, benzimidazoles, quinazolines, and quinazolinones, all of which are challenging to access. The control experiment involving TEMP18O suggests that the radical adduct of TEMPO with the benzyl radical of BHT may serve as an intermediate.
研究领域:
有机化学
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合成化学
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF ORGANOMETALLIC CHEMISTRY
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2023
·
IF 2.3
Run-Ze Yuan,Peng-Fei Cui,Guo-Xin Jin
Herein, we describe the synthesis of a series pincer-type half-sandwich complexes containing selective B(3)-H activation of m -carborane. Four pincer-type complexes containing Cp*M (M = Ir/Rh) and (η 6 -pcym)Ru metal-corner, ionic Cp*M[ m -C 2 B 10 H 9 (CS 2 CH 3 ) 2 ](CF 3 SO 3 ) (M = Ir ( 2 ), Rh ( 3 )), (η 6 -pcym)Ru[ m -C 2 B 10 H 9 (CS 2 CH 3 ) 2 ](CF 3 SO 3 ) ( 4 ) and neutral solvolysis product Cp*Ir[ m -C 2 B 10 H 9 (CS 2 CH 3 )(COS)] (Complex 5 ), have been prepared. The addition reaction of MeO − toward 2 3 and 4 causes the formation of moderately stable neutral unsymmetrical pincer-type complexes Cp*M{ m -C 2 B 10 H 9 (CS 2 CH 3 )[CS(SCH 3 )(OCH 3 )]} (M = Ir ( 6 ), Rh ( 7 )) and (η 6 -pcym)Ru{ m -C 2 B 10 H 9 (CS 2 CH 3 )[CS(SCH 3 )(OCH 3 )]} ( 8 ). The substitution reaction of 2 3 and 4 have also been also explored, unsymmetrical chelate complexes Cp*M( t BuNC)[ m -C 2 B 10 H 9 (CS 2 CH 3 ) 2 ](BPh 4 ) (M = Ir ( 9 ), Rh ( 10 )) can be obtained by using t BuNC and NaBPh 4 . All of these complexes have been characterized, including X-Ray single crystal diffraction, NMR spectroscopy, IR spectroscopy and elemental analysis methods.
研究领域:
无机化学
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配位化学
✓ 已验证
DOI
高影响因子
JOURNAL OF RARE EARTHS
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2022
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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.
研究领域:
催化化学
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生物质转化
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能源化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Building Engineering
·
2024
·
IF 6.7
Baomin Wang,Weigao Ding,Chengcheng Fan,Fei Liu,Wenxin Lu,Haoxiang Yang
C-S-H gel is a complex cementitious system, and the properties present significant difference with various Ca/Si ratios. The immobilization mechanism of three heavy metals in C-S-H gel at various Ca/Si ratios was investigated in this work from the prospect of the physical adsorption and chemical immobilization. Results showed that higher Ca/Si ratios can result in an increase in silicon chain polymerization, and lower BET specific area, and C-S-H gel with various Ca/Si ratios showed the excellent immobilization for heavy metals. Pb(II) and Zn(II) can form hydroxyl complex polyhedra in C-S-H under strongly alkaline environments, and increase the silicon chain polymerization degree similar to the doping of C-S-H gel by Al. However, Cd(II) was immobilized in the C-S-H gel with the formation of a solid solution under the action of ion exchange with Ca(II), rather than in the form of hydroxyl complex polyhedral and cadmium hydroxide coprecipitates. The highest adsorption capacity of Pb(II) was realized in C-S-H gel with a Ca/Si molar ratio of 0.9, reaching 95.6006 mg/g. Pb(II) was mainly immobilized in C-S-H gel via physical and chemical adsorption, and the effect of chemical adsorption tended to be significant as the Ca/Si molar ratio increased. And the formation of Pb 8 Ca(Si 2 O 7 ) 3 can be detected in C-S-H gel with a higher Ca/Si molar ratio.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2019
·
IF 4.084
Liangfeng Luo,Yidi Wang,Siping Huo,Peng Lv,Jun Fang,Yang Yang,Bin Fei
CuS/CdS(H)/CdS(C) photocatalysts were synthesized via the hydrothermal method by employing thiourea , Cd(CH 3 COO) 2 ·3H 2 O and copper 1,4-benzenedicarboxylate MOF (CuBDC). The photocatalysts were characterized by XRD , XPS , BET, TEM and UV–vis diffuse reflectance spectra. Interestingly, hexagonal CdS (CdS(H)) and cubic CdS (CdS(C)) were formed with phase junctions in one step when CuBDC was introduced in the synthesis process, in addition, CuS nanoparticles were deposited on CdS. However, only hexagonal CdS was obtained without CuBDC. It demonstrated that CuBDC was not only the precursor of CuS but also the structural modifier for CdS. With the reduction of re-combination of photo-induced electrons and holes caused by phase junctions and the enhancement of visible-light absorptions due to the loading of CuS, all CuS/CdS(H)/CdS(C) photocatalysts had higher photocurrent densities under visible-light irradiation, and consequently the higher rates of H 2 production than pure CdS(H). Typically, the catalyst with 2.89 wt% of Cu showed a highest rate of H 2 evolution at 2042 μmol/g/h.
研究领域:
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Yunzi Li,Fei Chen,Xiaoyu Li,Qiang Shen,Lianmeng Zhang
Ceramic/metal composites, as high-temperature structural materials, have limited applications because of their poor machinability . AlN/Mo/Mo 2 B machinable composites were fabricated by adding h-BN to AlN/Mo composites by plasma-activated sintering at various temperatures and at an axial pressure of 30 MPa under argon atmosphere. The sample sintered at 1500 °C exhibited excellent machinability for cemented carbide tools, with a bending strength of approximately 500 MPa and a Vickers hardness value of 9.34 GPa. The effects of sintering temperature on the microstructure, mechanical properties, and machinability were investigated, and the reactions introduced by adding h-BN were studied. These reactions reinforced the composite and newly introduced a Mo 2 B phase, which showed better ability to deflect cracks and prevent them from moving deep inside the composite, thus improving its machinability. This research provides a possible solution for improving the machinability of ceramic/metal composites without sacrificing the strength .
研究领域:
材料科学
·
机械工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）