MICROCHIMICA ACTA
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2019
·Vol. 186
·期 8
·1-10
·
IF 5.479
Zhou Yunlei,Jiang Wenjing,Wu Hanwen,Liu Fei,Yin Huanshun,Lu Nan,Ai Shiyun
A nanocomposite was prepared from β-cyclodextrin (β-CD) functionalized graphene oxide and magnetic nanoparticles (GO/Fe 3 O 4 /β-CD). In parallel, a polyamidoamine dendrimer conjugated to avidinylated alkaline phosphatase (PAMAM-avidin-ALP) was prepared and exploited as a signal amplification unit in a voltammetric immunoassay for 5-methylcytosine (5mC) in genomic DNA. The GO/Fe3O4/β-CD as a substrate material exhibited good solubility, electrical conductivity and large surface. This is beneficial for the further modification of antibodies (Ab) by host-guest interaction and amide bonds. By taking advantage of three-dimensional structure to capture avidin-ALP by amide linkages, PAMAM was used as a catalytic signal amplification element in this assay. Under the optimized condition and at a typical working potential of 0.94 V, the response to 5mC is linear in the 0.01–50 nM concentration range with a detection limit of 3.2 pM (at S/ N = 3). The method is stable, selective and reproducible. It was applied to the determination of 5mC in genomic DNA of human tissue.
An electrochemical immunoassay was constructed for 5-methylcytosine detection based on nanocomposite of graphene oxide, magnetite nanoparticles and β-cyclodextrin, and enzymatic signal amplification.
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JOURNAL OF HAZARDOUS MATERIALS
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2019
·
IF 7.65
Qin Zhu,Jiaorong Yan,Qiguang Dai,Qingqing Wu,Yuanpu Cai,Jinyan Wu,Xingyi Wang,Wangcheng Zhan
A unique zeolite catalyst, Fe doped ZSM-5 microsphere assembled by uniform nanorod-like crystals with hierarchical pore structure, was successfully synthesized and applied for the adsorption and degradation of trace chlorobenzene (CB) in the presence of H 2 O 2 . The organic ferric salts as the precursors, ethylene glycol as a chelating/reducing agent and the dynamic two-stage temperature-varied hydrothermal technique, together made the synthesized hierarchical Fe-ZSM-5 nanorods assembled microspheres (FZ-CA-5EG) to be characterized by abundant highly dispersed and valency-controlled framework Fe 3+/2+ species. As a result of these features, the FZ-CA-5EG showed excellent ability of adsorption and degradation efficiency of CB, and enhanced durability due to negligible leaching of framework Fe species. Moreover, the hydroxyl radicals were determined as the main the reactive oxygen species of CB oxidation degradation, and a possible adsorption-oxidation degradation pathway was proposed.
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APPLIED CATALYSIS A-GENERAL
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2019
·
IF 4.63
Yuxing Wang,Qingji Ying,Yaoyu Zhang,Yue Liu,Zhongbiao Wu
In this paper, the reaction behaviors of CH 3 CN catalytic combustion over CuCeO x -HZSM-5 catalysts prepared by the physical mixing and wet impregnation methods were investigated. The experimental results had revealed that the composite catalysts exhibited excellent degradation efficiency and high N 2 selectivity: the Cu-Ce oxides ensured the high activity, and the introduction of HZSM-5 limited the formation of NO x . The involved reaction mechanism was then studied by an in situ DRIFT analysis. It could be deduced that different reaction pathways would occur over CuCeO x and HZSM-5. The catalytic reaction over CuCeO x mainly proceeded via an oxidation pathway. The CN group could be converted to isocyanate species [NCO(a)] which would be further oxidized to NO x . Over HZSM-5, CH 3 CN was mainly hydrolyzed into ammonia. For the CuCeO x -HZSM-5 composite catalysts, the over-oxidation of NCO(a) and NH 3 was inhibited, and an internal selective catalytic reduction (SCR) reaction could occur, thereby greatly improving the N 2 selectivity.
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CATALYSIS TODAY
·
2018
·
IF 4.667
Mei Cui,Renliang Huang,Wei Qi,Rongxin Su,Zhimin He
2,5-Diformylfuran (2,5-DFF) is an important furan-based chemical with broad application potential. To address the difficulties in isolating/purifying the product and recycling the 2,2,6,6- tetramethylpiperidine-1-oxy (TEMPO)-based catalysts, we employed a solvent with a low boiling point in which TEMPO has a low solubility to investigate the effects of TEMPO and its analogs on catalyzing the oxidation of 5-hydroxymethylfurfural (5-HMF). The results indicated that in ethyl acetate with the substitution of one H of TEMPO at the C4 position with either an acetamido ( NH-Ac), methoxy ( OCH 3 ), hydroxy ( OH) or isothiocyanato ( N C S) group, the resulting compound had a product selectivity similar to that of TEMPO (>86%), except for the 4-isothiocyanato-TEMPO-catalyzed reaction. However, after two Hs were substituted with an oxo group ( O), the catalytic efficiency significantly decreased (product yield 16%, selectivity 52%). Based on both the catalytic efficiency and catalyst solubility, a highly efficient method for preparing 2,5-DFF was established using ethyl acetate as the solvent, 4-acetamido-TEMPO as the catalyst and Fe(NO 3 ) 3 and NaCl as cocatalysts. At 40 °C with a substrate concentration of 0.125 mol/L, 5-HMF was completely converted in 2 h, and the yield of 2,5-DFF was 89%. Moreover, when the substrate concentration increased to 0.25 mol/L, the yield of 2,5-DFF was 87%. When 4-acetamido-TEMPO was recovered by centrifugation, the product yield remained as high as 86% after three cycles, demonstrating good recyclability.
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APPLIED ENERGY
·
2018
·
IF 7.9
Xiaowen Zhang,Helei Liu,Zhiwu Liang,Raphael Idem,Paitoon Tontiwachwuthikul,Mohammed Jaber Al-Marri,Abdelbaki Benamor
The aim of this work is to find a potential way for great decrease in CO 2 capture energy requirement. Here, for the first time, a series of bifunctional Al 2 O 3 /HZSM-5 catalysts (Al-ZSM) were prepared by the combined precipitation ultrasound method and used for the CO 2 desorption process. All the investigated catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), N 2 adsorption–desorption, ammonia and CO 2 temperature programmed desorption (NH 3 /CO 2 -TPD) and pyridine-adsorption infrared spectroscopy (Py-IR). The regeneration behaviors of a 5 M monoethanolamine (MEA) solvent with four Al-ZSM catalysts were studied at an initial CO 2 loading of 0.5 mol CO 2 /mol amine and the temperature of 96 °C. The results reveal that all the catalysts improve the CO 2 desorption performance, the Al-ZSM catalysts show higher catalytic performance than the single catalysts Al 2 O 3 and HZSM-5, and the Al-ZSM can reduce the heat duty by 23.3–34.2% as compared with the catalyst-free test. The use of Al-ZSM in the MEA regeneration process improves the desorption performance by 2–3 times in comparison with the blank run. A possible dual sites mechanism of CO 2 desorption with Al-ZSM is suggested. The excellent performance of Al-ZSM can be attributed to their enhanced Brϕnsted acid sites (BAS), mesopore surface area (MSA) and basic sites, which resulted from the good synergistic reaction between the Al 2 O 3 and HZSM-5, and the base treatment for HZSM-5. Besides, the stability test of the Al-ZSM was conducted. Based on the results, the Al-ZSM demonstrate a superior catalytic performance for the rich amine regeneration process, and present an excellent cyclic stability, explicitly have the potential to be a promising industrial catalyst for CO 2 capture. Furthermore, the dual sites catalytic CO 2 desorption over bifunctional catalysts will open a new path to design better catalysts for the rich amine solution regeneration process to increase the desorption performance, reduce the regeneration energy consumption, and thus further decreasing the operation costs of CO 2 capture.
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JOURNAL OF POROUS MATERIALS
·
2018
·Vol. 26
·期 3
·793-802
·
IF 1.858
Wu Hong,Wang Xianshu,Liu Fei,Cao Jianxin
The SAPO-34/ZSM-5 composite catalyst (SZ-TS) was successfully fabricated using a two-step in situ crystallization method. X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, N 2 adsorption–desorption, and ammonia temperature-programmed desorption measurements were used to characterize the synthesized catalysts and evaluate their catalytic performances on methanol-to-olefin (MTO) reaction. The synthesis mechanism of two-step in situ crystallization was further investigated. Results showed that the SZ-TS synthesized by two-step in situ crystallization featured an intimately bonded composite structure owing to the synergistic effects of the interface. However, the physical mixture of SAPO-34 and ZSM-5 (SZ-PM) presented two discrete phase structures. By using the composite catalyst in MTO reaction, the SZ-TS exhibited the longest life of 1400 min, which was much higher than that of SZ-PM (720 min). Methanol conversion reached 97.3%, and the selectivity for light olefins totalled 93.0%. The excellent catalytic performance of SZ-TS was attributed to the hierarchical pore structure and suitably weak acid site distribution. Via pre-crystallization, alkalinity can be adjusted in the adjacent ranges of SAPO-34 and ZSM-5. By adding the pre-crystallized alkaline SAPO-34 slurry into the strong alkaline system of the parent ZSM-5 slurry, phase dissolution of SAPO-34 in the secondary crystallization solution was avoided. The external surface of SAPO-34 was etched in the alkaline environment of the secondary crystallization solution, resulting in hierarchical pore distribution, which benefited the MTO reaction. This in situ synthesis method features the advantages of simplicity, low time consumption, and low cost. Therefore, this approach possesses the potential to satisfy the demands of the MTO market.
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BIORESOURCE TECHNOLOGY
·
2019
·
IF 6.669
Xin Zhang,Ziguo Yuan,Qian Yao,Ying Zhang,Yao Fu
In this work, corn cob was used as raw material to selectively produce acetonitrile via catalytic fast pyrolysis (CFP) in ammonia over Ga/HZSM-5 catalyst. A series of catalysts with different catalyst carriers (including HZSM-5, USY, MCM-41, HY, and γ-Al 2 O 3 ) and active metals (including Fe, Co, Ni, Cu, Zn, Cr, Ca, Mg and Ga) were prepared and screened. The reaction conditions, such as temperature, ammonia flow rate and residence time were changed to investigate the effect on the product distribution and acetonitrile production. The results indicated that with the desired catalyst (2% Ga/HZSM-5) and optimal reaction conditions (Temperature 700 °C; ammonia flow rate 80 ml/min; residence time 2.4 s), the highest carbon yield of acetonitrile from corn cob with a value of 18.4% could be obtained, and the carbon selectivity in bio-oil was 83.5%. This study provides an economical and environmental-friendly method for the direct production of acetonitrile from abundant biomass.
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FOOD RESEARCH INTERNATIONAL
·
2019
·
IF 3.579
Yuting Wang,Huiyu Hu,David Julian McClements,Shaoping Nie,Mingyue Shen,Chang Li,Yousheng Huang,Yadong Zhong,Jie Chen,Maomao Zeng,Mingyong Xie
The effect of unsaturated free fatty acids (FFAs) and triglycerides (TGs) on the formation of acrylamide and 5-hydroxymethylfurfural (HMF) at frying temperature was investigated. We hypothesized that the nature of the precursors generated by the Maillard reaction in the presence of FFAs and TGs, such as the Amadori product and α-dicarbonyl compounds, would impact acrylamide and HMF formation. Interestingly, the initial pH of the aqueous phase impairs the observed effect of the addition of lipids on the formation of acrylamide. Addition of FFAs and TGs increased acrylamide formation in non-buffered systems (distilled water, pH 4.6), but decreased it in buffered systems (sodium acetate, pH 6.0). Conversely, incorporation of these lipids promoted HMF formation under both conditions. The degree of fatty acid unsaturation played an important role in the formation of acrylamide and HMF. The effect of unsaturated lipids on the acrylamide and HMF was due to lipid oxidation. Statistical correlations were made between acrylamide and HMF formation and α-dicarbonyl compounds in the presence of unsaturated lipids.
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GREEN CHEMISTRY
·
2018
·Vol. 20
·期 21
·4946-4956
·
IF 8.586
Yongshen Ren,Ziliang Yuan,Kangle Lv,Jie Sun,Zehui Zhang,Quan Chi
The development of new strategies for metal-free promoted reactions has recently received great interest from chemists because these processes benefit from the use of inexpensive catalysts and from avoidance of contamination of the desired products by the metal catalysts. In this study, a method for HNO3-promoted oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) was developed in the presence of nitrogen-doped carbon materials using molecular oxygen as the terminal oxidant under mild reaction conditions. The catalytic activity of the nitrogen-doped carbon materials was discovered to greatly increase with increasing pyrolysis temperature; it also depended on both the type of nitrogen atoms in the catalyst and the surface area of the catalyst. The NC-950 catalyst demonstrated unprecedented catalytic activity towards the oxidation of HMF to DFF. Several reaction parameters, such as the reaction solvent, the reaction temperature, the amount of HNO3, the catalyst loading and the oxygen pressure, have been investigated. The highest DFF yield of 95.1% was attained with full HMF conversion after 14 h at 100 °C under 10 bar oxygen pressure in the presence of a catalytic amount of HNO3. Control experiments indicated that the oxidation of HMF was initially promoted by HNO3, and O2 acted as a secondary oxidant for HNO3 recovery. In particular, the NC-950 catalyst had remarkable reusability without significant losses in its activity and selectivity after six consecutive usages.
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ACS Catalysis
·
2014
·
IF 7.572
Jinzhu Chen,Ruliang Liu,Yuanyuan Guo,Limin Chen,Hui Gao
A catalyst of palladium [Pd/MIL-101(Al)-NH2] supported on amine-functionalized Metal–Organic Frameworks (MOFs) allows selective hydrogenation of biomass-based 5-hydroxymethylfurfural (HMF) to 2,5-dihydroxymethyl-tetrahydrofuran (DHMTHF) with 2,5-dihydroxymethylfuran (DHMF) as an observed “intermediate”. The Pd/MIL-101(Al)-NH2 was prepared by using a direct anionic exchange approach and subsequent gentle reduction. The presence of free amine moieties in the frameworks of MIL-101(Al)-NH2 is suggested to play a key role on the formation of uniform and well-dispersed palladium nanoparticles on the support. The adsorption experiments reveal that the amine-functionalized MOF supports show preferential adsorption to hydrogenation intermediate DHMF than in the case of reactant HMF owing to an enhanced hydrophilic nature of DHMF as well as improved hydrogen bonding interactions between DHMF and the MOF support, which promotes a further hydrogenation of DHMF to DHMTHF upon the in situ formation of DHMF over Pd/MIL-101(Al)-NH2. Moreover, our results also indicate that the observed high selectivity toward DHMTHF form HMF is closely related to the cooperation between the metallic site and the free amine moiety on the MOF support. Under the optimal conditions, a maximum DHMTHF yield of 96% with a full conversion of HMF is obtained by using Pd/MIL-101(Al)-NH2 (Pd 3.0 wt %) catalyst at a low reaction temperature of 30 °C in aqueous medium. The research thus highlights new perspectives for aluminum-based and amine-functionalized MOF material for biomass transformation.
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Energy Technology
·
2013
·
IF 0
Hu Li,Xudong He,Qiuyun Zhang,Fei Chang,Wei Xue,Yuping Zhang,Song Yang
The dehydration of fructose to 5-hydroxymethylfurfural (HMF) in the presence of a SO 3 H-functionalized heteropolyanion-based polymeric hybrid catalyst is investigated. Poly(1-vinyl-3-propane sulfonate imidazolium)-H 3 PW 12 O 40 [poly(VMPS)-PW], a supported ionic liquid catalyst (SILC) was prepared and used as a heterogeneous Brønsted-acidic catalyst. We demonstrate that an 83% yield of HMF can be obtained at 130 ºC after 60 min using DMSO as the solvent, under atmospheric pressure. The catalytic scope of poly(VMPS)-PW is studied by using it as a catalyst for the dehydration of glucose. We demonstrate that the catalyst is also suitable for conversion of glucose to HMF, with a yield of 26 % under mild conditions. Moreover, the acidic hybrid catalyst is easily separated from the reaction mixture by centrifugation. The ability to recycle the catalyst is demonstrated and poly(VMPS)-PW is reused five times without significant loss of activity.
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CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY
·
2014
·Vol. 42
·期 2
·146-153
·
IF 2.405
Xiao-Yun Hu,Ji-Yun Liang,Xue-Jun Guo,Li Liu,Ya-Bing Guo
Summary The development of chemoresistance may reduce the efficacy of chemotherapeutic drugs for treating hepatocellular carcinoma (HCC). In the present study, the effects of apigenin on intensifying the chemosensitivity of HCC cells and an HCC xenograft model in response to 5-fluorouracil (5-FU) were investigated. Sub-toxic concentrations of apigenin (4 μ mol/L) significantly enhanced the cytotoxicity of 5-FU (100 μ g/mL) in HCC cells. In vivo , combined treatment with apigenin (20 mg/kg, five times/week for 3 weeks) and 5-FU (20 mg/kg for 5 consecutive days) significantly inhibited the growth of HCC xenograft tumours. Annexin V–propidium iodide dual staining assays, terminal deoxyribonucleotidyl transferase-mediated dUTP–digoxigenin nick end-labelling assays and western blotting analysis were used to confirm the synergistic effects of apigenin and 5-FU on HCC apoptosis. Coincubation of HCC cells with apigenin and 5-FU increased levels of reactive oxygen species (ROS), which was followed by a decrease in the mitochondrial membrane potential (ΔΨm). In addition, combined triggered the mitochondrial apoptotic pathway, as indicated by decreased Bcl-2 expression and loss of ΔΨm, with significant activation of caspase 3 and poly(ADP-ribose) polymerase. The present study is the first to demonstrate that apigenin may potentiate the cytotoxicity of 5-FU in HCC via inhibition of ROS-mediated drug resistance and concurrent activation of the mitochondrial pathways of apoptosis.
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