JOURNAL OF CHROMATOGRAPHY A
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2019
·
IF 3.858
Chunjian Wu,Li Wang,He Li,Shujuan Yu
The presence of potential carcinogen 4(5)-Methylimidazole (4-MeI) in foods causes much concern, stressing the need of a sensitive determination means. Here, we proposed a high-sensitivity method to determine 4-MeI in biscuits using dansyl chloride derivatization and disperse liquid-liquid micro-extraction (DLLME) followed by a liquid chromatography-ion trap mass spectrometry (LC-IT-MS) analysis. This developed method was subsequently compared to the solid phase extraction combining with liquid chromatography-triple quadrupole mass spectrometry (SPE-LC-QqQ-MS) method. The optimized derivatization conditions were 30 °C and 10 min. Results suggested that the column retention time (RT) was significantly extended, and the MS signal response of 4-MeI-dansyl derivative was also amplified. The developed DLLME-LC-IT-MS method in 4-MeI determination provided satisfactory linearity in a range of 0.5–300 ng/mL (R 2 > 0.9991), inter-day accuracy (87-102%) and precision (%RSD ≤ 13.6%) with the quantification limit of 0.2 ng/mL, which obtained similar results comparing to the conventional SPE-LC-QqQ-MS method.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2019
·
IF 3.375
Fuxiang Feng,Li Wang,Xiangwen Zhang,Qingfa Wang
HZSM-5 zeolite has been extensively utilized in the petrochemical and fine chemical industry owing to its excellent isomerization/cracking activity and hydrothermal stability. However, it still remains a great challenge for ZSM-5-supported catalysts to upgrade vegetable oils to aviation-fuel-range-alkanes (AFRAs). Herein, an efficient Ni/ZSM-5 catalyst composed of self-pillared (SP) nanosheets along with high external acid fraction and short characteristic diffusion length was synthesized and employed for this reaction. This SP Ni/ZSM-5 nanosheet catalyst shows high deoxygenation, cracking/isomerization activity, and excellent catalytic stability for upgrading oleic acid to AFRAs, which is attributed to the SP nanosheet structure and reasonable acid distribution. Last, a high AFRA yield of 40% with an iso/n-alkanes ratio of 1.8 was achieved.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2019
·
IF 3.218
Jing Sun,Fang Guo,Qiaofang Shi,Huayu Wu,Yan Sun,Ming Chen,Guowang Diao
In this paper, silver nanoparticles (AgNPs) modified by carboxylated pillar[5]arene (CP5) were anchored on graphene oxide (GO) by π-π stacking interaction and hydrogen bond between CP5 molecules and GO. The obtained hybrid nanomaterials CP5-AgNPs/GO were characterized by ultraviolet-visible adsorption spectrometer, Fourier transform infrared adsorption spectrometer, and transmission electron microscopy . Testing of various electrochemical techniques displays that the CP5-AgNPs/GO modified glass carbon electrodes (GCE) show good electrocatalytic property , molecular recognition and enrichment performance toward paraquat (PQ) and exhibit high current response. Compared with other modified electrodes , such as GO/GCE and CP5/GO/GCE, CP5-AgNPs/GO/GCE shows an outstanding electrochemical response for PQ with high sensitivity of 78.8 mA mmol −1 L cm −2 . The analytical curves for PQ obtained by differential pulse voltammetry are linear in the range from 1.0 × 10 −8 to 1.0 × 10 −5 M and from 2.0 × 10 −5 to 7.0 × 10 −5 M. The limit of detection is 1.0 × 10 −8 M (S/N = 3). This excellent performance is ascribed to the synergic electrocatalytic effect of AgNPs and GO, and the host-guest recognition of CP5 for PQ.
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CATALYSIS TODAY
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2019
·
IF 4.888
Yiwen Jiang,Ling Zhang,Yiquan Xie,Shichao Han,Qiuyan Zhu,Xiangju Meng,Feng-Shou Xiao
A series of zeolite-supported Pt nanoparticles (Pt/NaZSM-5) have been prepared by adjusting Si/Al ratio of NaZSM-5 zeolite from 60 to pure silica. Catalytic tests in propene oxidation as an important model reaction for removal of hydrocarbons emitted from automobiles during cold-start, show that the catalytic activities significantly increase with Si/Al ratios of NaZSM-5 zeolite in these Pt/NaZSM-5 catalysts. As a typical example, Silicalite-1 supported Pt nanoparticles exhibits the highest activity, giving the 50% conversion temperature (T 50 ) and 90% conversion temperature (T 90 ) at 112 °C and 118 °C, respectively. Characterizations of these catalysts with multiple techniques show that the enhanced catalytic activities are strongly related to the zeolite Si/Al ratios of the catalysts, where an increase of zeolite Si/Al ratio is favorable for the adsorption of propene, promoting the propene oxidation. This feature might offer a good opportunity to design and prepare highly efficient heterogeneous catalysts for removal of light olefins in the future.
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BIOLOGICAL & PHARMACEUTICAL BULLETIN
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2019
·Vol. 42
·期 6
·886-891
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IF 1.54
Yangbiao He,Xujun Lang,Dong Cheng,Zhihao Yang
Previous studies implicated the mammalian target of rapamycin (mTOR)/hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) pathway in renal fibrosis and found that curcumin could suppress the expression of mTOR. Therefore, the aim of the present study was to investigate the therapeutic effects of curcumin against chronic renal failure (CRF) in a rat model induced by 5/6 nephrectomy through inhibition of mTOR/HIF-1α/VEGF signaling. A total of 70 male Sprague–Dawley rats were divided into seven groups: a sham group, a CRF group, and five treatment groups. Except for the sham rats, all rats underwent 5/6 nephrectomy to induce CRF. The 5/6 nephrectomized rats received treatment with curcumin vehicle, everolimus vehicle, curcumin, everolimus, or the combination of curcumin and everolimus. Everolimus, a specific inhibitor of mTOR, was used as a positive control. At the end of treatment, blood biochemical indexes, proteinuria and the kidney index were detected. Moreover, histological change was examined by hematoxylin and eosin staining, and protein expression levels were detected by Western blotting. The blood biochemical indexes, proteinuria, and kidney index were increased in the CRF group as compared to the sham group, which was accompanied by marked activation of the mTOR/HIF-1α/VEGF pathway. However, curcumin, as well as everolimus, restored or ameliorated these changes. These results indicate that activation of the mTOR/HIF-1α/VEGF signaling pathway plays an important role in the occurrence and development of CRF, and that curcumin has renoprotective effects by blocking activation of this pathway.
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Advanced Healthcare Materials
·
2019
·Vol. 8
·期 22
·1900896
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IF 6.27
Jinjin Zhu,Liyun Dong,Hongyao Du,Jinzhu Mao,Ying Xie,Hua Wang,Jiajia Lan,Yuchen Lou,Yangxue Fu,Jingjing Wen,Biling Jiang,Yuce Li,Jintao Zhu,Juan Tao
5-Aminolevulinic acid (5-ALA) is one of the most widely used prodrug in clinical photodynamic therapy of dermatological diseases and cancers; yet, its clinical application is still limited by the shallow skin penetration and unsatisfied stability in any existed formulations. Here, 5-ALA-loaded hyaluronic acid dissolving microneedles (5-ALA@HAMNs) are prepared for photodynamic therapy of superficial tumors. The HAMNs can not only assist the loaded 5-ALA to effectively penetrate the stratum corneum but also provide 5-ALA with an acidic and oxygen-free environment to reduce the dimerization of 5-ALA molecules via Schiff-base bonds and formation of inactive pyrazine derivatives, thus maintaining its chemical structure and biological activity. The chemical stability of 5-ALA in HAMNs is confirmed by UV–vis spectra and mass spectra measurements. The 5-ALA@HAMNs display remarkable tumor elimination both in vitro and in vivo, even after storage at room temperature for nine months, making it a highly potential device for effective delivery of 5-ALA in cancer photodynamic therapy.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2019
·
IF 3.375
Jian Zhang,Liang Wang,Zhiyi Wu,Hai Wang,Chengtao Wang,Shichao Han,Feng-Shou Xiao
We report the synthesis of Zn/ZSM-5 particles coated with a silicalite-1 zeolite shell (core–shell Zn/ZSM-5@silicalite-1) via grinding of the raw silica source materials with TPAOH and Zn/ZSM-5, followed by solvent-free crystallization at 180 °C for 72 h. The product was well characterized by the XRD patterns, N2 sorption isotherms, SEM images, and TEM images. Because of the core–shell structure, the Zn/ZSM-5@silicalite-1 sample exhibits high selectivities for benzene, toluene, and xylenes in the conversion of methanol, compared with those over ZSM-5 and Zn/ZSM-5 samples. The solvent-free synthesis offers an alternative method for preparing core–shell Zn/ZSM-5@silicalite-1 catalysts.
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CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Xiaoxia Ou,Fotios Pilitsis,Yilai Jiao,Yong Zhang,Shaojun Xu,Martin Jennings,Yi Yang,S.F. Rebecca Taylor,Arthur Garforth,Huiping Zhang,Christopher Hardacre,Ying Yan,Xiaolei Fan
Structured Fe-ZSM-5 zeolite supported on silicon carbide (SiC) foam catalyst was develop and applied as the packed foam bed catalytic reactor (FBCR) to the liquid phase catalytic wet peroxide oxidation (CWPO) of phenol under flow conditions. Fe catalysts were uniformly incorporated into ZSM-5 coatings using chemical vapour deposition (CVD). Fluid flow analysis of FBCR was performed by varying liquid flow rate, showing the transition of reactor type from the plug flow reactor to the continuous stirred tank reactor at about 1 ml min −1 . Systematic investigation of CWPO within Fe-ZSM-5/SiC FBCRs identified the optimum condition of operating the FBCR (80 mm bed length) as at 60 °C and 1 ml min −1 with the turnover frequency (TOF) of 95 h −1 for phenol degradation (apparent activation energy = 3.4 kJ mol −1 ) and total organic carbon (TOC) conversion of 45.5%. It was believed that the enhanced macromixing promoted by cellular foam supports was accountable for the observed catalytic performance. The longevity of FBCR under flow conditions was also assessed, showing its good stability over 24 h, as well as the potential for practical adoption.
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FOOD CHEMISTRY
·
2018
·
IF 4.946
Chunjian Wu,Li Wang,He Li,Shujuan Yu
The determination of carcinogenic 4(5)-methylimidazole (4-MeI) in complex matrices at trace levels is a challenge because of its higher polarity and weaker column retention capability. Here, we proposed a novel method for the quantification of 4-MeI in various foods and beverages using modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The evaluated QuEChERS extraction with LC-MS/MS method showed excellent linearity (1–200 μg/L, with correlation coefficient (R 2 ) > 0.999), trueness (91–113%), and precision (relative standard deviation (RSD) ≤ 12.3%), but low matrix effect (92–108%) for cola, tea, beer, coffee beverage, bread, biscuit and instant coffee. The expanded measurement uncertainty was less than 34.4% at 95% confidence level. The proposed method can be successfully applied to determine 4-MeI in 28 commercial foods and beverages purchased from local market. Therefore, we believe this method is likely to provide a potential for 4-MeI determination in practical application.
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APPLIED CATALYSIS A-GENERAL
·
2018
·
IF 4.521
Zihao Zhang,Changxue Wang,Xin Gou,Hao Chen,Kequan Chen,Xiuyang Lu,Pingkai Ouyang,Jie Fu
A series of Cu-based catalysts with different supports were synthesized and studied for the in situ hydrogenation of 5-hydroxymethylfurfural (5-HMF) to dimethylfuran (DMF) using methanol as an economical hydrogen donor. The structures and properties of the four catalysts (Cu/Al 2 O 3 , Cu/ZnO, Cu/ZrO 2 , and Cu/CeO 2 ) were characterized using X-ray diffraction (XRD), temperature-programmed reduction (H 2 -TPR), and temperature-programmed desorption of ammonia (NH 3 -TPD). The experimental results showed that the use of different supports for the Cu-based catalysts significantly influenced their activity for both H 2 production from methanol and hydrogenation of 5-HMF. The catalyst Cu/Al 2 O 3 showed the best catalytic activity, which can be attributed to the highest activity for the in situ H 2 production from methanol, smallest Cu crystallite size, and strongest acidity. The effects of the substrate concentration, catalyst loading, and reaction temperature and time on the in situ hydrogenation of 5-HMF were systematically investigated to determine the optimum reaction conditions.
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MICROCHIMICA ACTA
·
2018
·Vol. 185
·期 4
·1-8
·
IF 5.705
Liu Xiaojie,Lin Bixia,Yu Ying,Cao Yujuan,Guo Manli
A multifunctional fluorescent probe is synthesized for the determination of adenosine 5′-triphosphate (ATP). The 6-carboxyfluorescein-labeled aptamer (FAM-aptamer) was bound to the surface of magnetite nanoparticles coated with polydopamine (Fe 3 O 4 @PDA) by π-π stacking interaction to form the multifunctional probe. The probe has three functions including recognition, magnetic separation, and yielding a fluorescent signal. In the presence of ATP, FAM-aptamer on the surface of the probe binds to ATP and returns to the solution. Thus, the fluorescence of the supernatant is enhanced and can be related to the concentration of ATP. Fluorescence intensities were measured at excitation/emission wavelengths of 494/526 nm. Response is linear in the 0.1–100 μM ATP concentration range, and the detection limit is 89 nM. The probe was applied to the quantitation of ATP in spiked human urine and serum samples, with recoveries ranging between 94.8 and 102%.
A multifunctional fluorescent probe based on the use of FAM-aptamer and Fe 3 O 4 @PDA is described for the determination of ATP in spiked human urine and serum samples. FAM-aptamer: 6-carboxyfluorescein-labeled aptamer; Fe 3 O 4 @PDA: magnetite nanoparticles coated with polydopamine. ATP: adenosine 5′-triphosphate.
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Nanoscale
·
2013
·Vol. 5
·期 6
·2454-2459
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IF 6.233
Baoru Bian,Weixing Xia,Juan Du,Jian Zhang,J. Ping Liu,Zhaohui Guo,Aru Yan
By using Fe(CO)x-OAm (oleylamine, x < 5) as the Fe precursor to slow down the formation rate of FePt nanoparticles (NPs), a time dependence of the NPs' nucleation and growth process was observed by transmission electron microscopy (TEM). The complexing temperature of OAm and Fe(CO)5 at which Fe(CO)x-OAm was formed has a strong influence on the nucleation rate and growth process of the NPs. TEM analyses indicated that the NPs with isotropic shape were single crystalline throughout the synthesis and were formed by a diffusion-controlled Ostwald-ripening (OR) growth mechanism. The nanorod particles were first formed via joining of arbitrarily oriented single crystals and the two crystals formed a uniform particle afterwards, as described by the oriented-attachment (OA) mechanism. The ratio of OAm to Fe(CO)5 used in the preparation of Fe(CO)x-OAm has a significant influence on the growth process, and subsequently the shape, size and size distribution of the FePt NPs. By adjusting the ratio and its complexing temperature, single-crystal FePt NPs with controllable size and isotropic shape were obtained. The insight into the exploration of the specific roles of the reaction conditions and the formation mechanisms provided important information for controlling the morphology of the nanoparticles.
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