JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC
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2015
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IF 2.128
Hui Fei,Gang Xu,Jian-Ping Wu,Li-Rong Yang
DERA SEP (2-deoxy- d -ribose-5-phosphate aldolase cloned from Staphylococcus epidermidis ) shows higher catalytic activity toward 2-deoxy- d -ribose-5-phosphate (DRP) than that of DERA ECO (2-deoxy-ribose aldolase cloned from Escherichia coli ). However, the acetaldehyde tolerance of DERA SEP is still at low level, which limits its use in large-scale applications. Although the mechanism responsible for enzyme inactivation in the presence of solvents is unclear, earlier work indicated the positive correlation between the tolerance of an enzyme for organic solvents and the rigidity of its structure. The acetaldehyde tolerance of DERA SEP was improved by site-directed mutagenesis on the basis of enhancing the rigidity of the protein structure. After calculating the virtual mutation energy (stability) of the enzyme and experimental verification, variant 10 mutant DERA SEP with three amino acid substitutions (T120C, G174I, and G213C) was harvested after three rounds of site-directed mutagenesis. It showed surprisingly high tolerance to acetaldehyde, with almost 70.5% residual catalytic activity after exposure to 300 mM acetaldehyde for 2 h, while the wild-type DERA SEP retained only 11.3% activity under the same condition. Because the rigidity of the protein was increased after incorporating the mutations, the specific activity of the variant 10 was only half that of DERA SEP . Thus, the acetaldehyde tolerance of DERA SEP was efficiently increased by enhancing the rigidity of the structure. These results suggested that the inactivation of DERA by exposure to acetaldehyde may result from protein structural damage.
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SENSORS AND ACTUATORS B-CHEMICAL
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2014
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IF 3.84
Xueqin Wang,Yan Li,Xiaoqi Li,Jianyong Yu,Salem S. Al-Deyab,Bin Ding
Determination of environmental contaminants such as trace formaldehyde mostly relies on bulky and costly analytical equipment. However, a particular demand for portable, rapid, and sensitive method that can be used in resource-limited settings has received paramount concern. Towards this need, we are presenting here a rational design of colorimetric sensor strips using electrospun cellulose nanofibrous membrane-immobilized pararosaniline. Based on the specific reaction between formaldehyde and pararosaniline, the strips could undergo a distinct color transition from light pink to purple, specifically in the presence of trace-level formaldehyde over other possible interferential volatile organic compounds. Benefiting from the large specific surface area and high porosity of nanofibrous membranes, the strips achieved ultralow naked eye detection limit of 0.06 mg m −3 (below the regulatory level of 0.1 mg m −3 ), wide linear range from 0.12 to 6 mg m −3 , and short response time (15 min) in the absence of advanced instrumentation. Additionally, the sensing responses were visualized quantitatively by HSI coordinates which are presented with lightness and chromatic values and analyzed by a principal component analysis method. Furthermore, the strips exhibited remarkably improved analytical performance compared to commercial filter paper-based ones. With its cost-effective design and portability, this sensitive and specific colorimetric strips could potentially be used for providing air contamination information.
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JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE
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2014
·Vol. 95
·期 5
·915-921
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IF 1.879
Liang Dong,Yingmin Hou,Feng Li,Yongzhe Piao,Xiao Zhang,Xiaoyu Zhang,Cheng Li,Changxin Zhao
BACKGROUND Beer is a popular alcoholic malt beverage resulting from fermentation of the aqueous extract of malted barley with hops. The aroma of brewing barley impacts the flavor of beer indirectly, because some flavor compounds or their precursors in beer come from the barley. The objectives of this research were to study volatile profiles and to characterize odor-active compounds of brewing barley in order to determine the variability of the aroma composition among different brewing barley cultivars. RESULTS Forty-one volatiles comprising aldehydes, ketones, alcohols, organic acids, aromatic compounds and furans were identified using solid phase microextraction combined with gas chromatography/mass spectrometry, among which aldehydes, alcohols and ketones were quantitatively in greatest abundance. Quantitative measurements performed by means of solvent extraction and calculation of odor activity values revealed that acetaldehyde, 2-methylpropanal, 3-methylbutanal, 2-methylbutanal, hexanal, heptanal, octanal, nonanal, 3-methyl-1-butanol, cyclopentanol, 2,3-butanedione, 2,3-pentanedione, 2-heptanone, acetic acid, ethyl acetate, 2-pentylfuran and benzeneacetaldehyde, whose concentrations exceeded their odor thresholds, could be considered as odor-active compounds of brewing barley. CONCLUSION Principal component analysis was employed to evaluate the differences among cultivars. The results demonstrated that the volatile profile based on the concentrations of aroma compounds enabled good differentiation of most barley cultivars. © 2014 Society of Chemical Industry
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BIORESOURCE TECHNOLOGY
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2017
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IF 5.651
Guochao Xu,Yaping Zhang,Yue Wang,Ye Ni
In this work, genome hunting strategy was adopted in screening for reductases from Candida glabrata . A total of 37 putative reductases were successfully expressed in E. coli BL21(DE3). A substrate library containing 32 substrates was established for characterization of each reductase by average specific activity and Shannon-Wiener index. Among them, Cg26 was identified with the highest efficiency and wider substrate spectrum in the reduction of prochiral ketones, with average activity and Shannon-Wiener index of 8.95 U·mg −1 and 2.82. Cg26 is a member of ‘extended’ short chain dehydrogenase/reductase superfamily. Ni 2+ could improve its activity. As much as 150 g·L −1 ethyl 2-oxo-4-phenylbutyrate could be completely converted by 10 g·L −1 Cg26. This study provides evidence for this newly identified Cg26 in the preparation of chiral secondary alcohols.
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ANALYTICA CHIMICA ACTA
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2017
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IF 4.95
Yao Sun,Zhaobing Guan,Hongwei Cai,Yiyong Huang,Yawei Lin,Xiaosong Hu
A pre-column fluorescent derivatization method based on nitrone formation has been applied to determine furfurals (e.g. furfural (F), 5-methyfurfural (5-MF) and 5-hydroxymethylfurfural (5-HMF)) in food samples for the first time. An N-substituted hydroxylamine reagent 4-((hydroxyamino)butyl)-7-hydroxycoumarin (HAHC) was used to react with the aldehyde group of furfurals to form stable nitrone derivatives with high fluorescence intensities . The reactions proceeded under mild conditions in 30 min with high derivatization yields (>93%). A baseline-separation of three furfurals derivatives was subsequently achieved within 25 min on a reversed-phase column. The detection limits were at the low femtomol level (S/N = 3, 20 μL per injection). The linear range of the calibration curve was 0.4–4000 nM with good correlation coefficients (R 2 ≥ 0.9991). The proposed method was further applied for food sample analysis, such as bovine milk powder and raisin. Satisfactory recoveries were obtained in the range of 94.7%–103.5%. Above all, this pre-column derivatization method is simple, fast and highly sensitive, providing an effective and promising way for future studies of aldehydes in different matrices.
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ANALYTICAL CHEMISTRY
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2017
·
IF 6.32
Zhengyi Chen,Gongke Li,Zhuomin Zhang
It still remains a great challenge for quantification of trace analytes in complex samples by surface-enhanced Raman scattering (SERS) technique due to potential matrix influence or weak SERS responses of analytes. In this work, a miniaturized thermal-assisted purge-and-trap (MTAPT) device was designed and developed to eliminate matrix influence coupled with derivatization method before SERS analysis. The design of MTAPT chamber was optimized based on quantitative calculation of its dead volume by computational fluid dynamics simulation. The small straight chamber was selected as an optimized design with a recovery of 96.1% for formaldehyde. The practical feasibility of MTAPT was validated based on four real analytical applications including phenthiol in industrial water, formaldehyde in flour, sulfion in wastewater, and methanol in industrial alcohol. The results showed that SERS responses of all analytes dramatically increased by eliminating sample matrices after MTAPT process. Phenthiol, formaldehyde, sulfion, and methanol in real samples could be accurately quantified with recoveries of 80.9–110.0%, and the analytical results were validated by corresponding standard methods. The time consumption of MTAPT-SERS for real sample analysis including sample preparation and determination was within 16 min. It is highly expected that the combination of MTAPT technique with portable SERS instrument can greatly expand the range of SERS analysis. The proposed MTAPT-SERS method has high potential for on-site analysis of complex samples.
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ChemSusChem
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2017
·Vol. 10
·期 23
·4715-4724
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IF 7.226
Wenda Hu,Yan Wan,Lili Zhu,Xiaojie Cheng,Shaolong Wan,Jingdong Lin,Yong Wang
Graphical Mal to Mol and Dal ! Methylallyl alcohol and diethyl acetal are synthesized from methacrolein by using different Sn-modified Beta zeolites (Sn-β) as catalysts. The Sn-β precalcined in Ar followed by sodium-exchange exhibited the highest selectivity toward the desired products. The possible reaction pathways of the reaction between α,β-unsaturated aldehydes and primary alcohols were investigated and proposed. A new strategy was developed to simultaneously produce two important chemicals, namely, methallyl alcohol (Mol) and diethyl acetal (Dal) from methacrolein in ethanol solvent at low temperature with the use of Beta zeolites modified by tin (Sn-β catalysts). All the Sn-β catalysts were prepared by the solid-state ion-exchange method, wherein the calcination step was conducted under different gas atmospheres. The catalyst precalcined in Ar (Sn-β-Ar) had a reduced number of extra-framework Sn species and enabled more Sn species to be exchanged into the framework as isolated tetrahedral Sn IV , enhancing the catalytic activity of the Meerwein–Ponndorf–Verley (MPV) reaction. The sodium-exchanged Sn-β-Ar, with a reduced number of weak Brønsted acid sites, led to an even better selectivity for Mol, owing to the restriction of the side reactions such as acetalization, addition, and etherification. Under optimized catalyst and reaction conditions, the yield of Mol and Dal reached approximately 90 % and 96 %, respectively. The possible reaction pathways, along with a complex network of side products, was proposed after a detailed investigation through the use of different substrates as reactants. The fine-tuning of Sn-β catalysts through different treatments discussed in this work is of great significance toward the understanding and manipulation of complex reactions between α,β-unsaturated aldehydes and primary alcohols.
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RSC Advances
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2016
·Vol. 6
·期 88
·84815-84824
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IF 3.289
Hui Liu,Xiaoxia Xue,Tiesheng Li,Jiong Wang,Wenjian Xu,Minghua Liu,Penglei Chen,Yangjie Wu
A series of self-assembled Pd(II)–alkyl Schiff base complexes [PdLn–Si] (Cat. 1–5) [n = 0, 1, 3, 6, 10] having different chain lengths were synthesized and characterized by water drop contact angle (WDCA), atomic force microscopy (AFM), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy (RS), and X-ray photoelectron spectroscopy (XPS) analyses. Catalyst 3 with a moderate alkyl chain exhibited highly active and recyclable properties for the Suzuki coupling reaction, which indicated that the length of the alkyl chain significantly affects the catalytic activity due to a suitable orientation and electron-rich environment which make it easy to form palladium–ligand bonds, stabilize the active species and facilitate the insertion of this metal into the Ar–X bond. The catalytic mechanism was also investigated, in which a three-phase test indicated that the self-assembled complexes act as true heterogeneous catalysts. The catalytic process was analyzed by RS and XPS, indicating it is a surface catalysis process.
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RSC Advances
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2017
·Vol. 7
·期 12
·7140-7149
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IF 3.108
Yuchao Xu,Zongzhang Liu,Zheng Han,Minhua Zhang
ZnO promoted ZrO2–SiO2 catalysts synthesized by a sol–gel method were investigated in the two-step ethanol transforming to 1,3-butadiene process. The influence of promoters and the preparation method of the catalysts on the catalytic performance were studied in detail and the reaction conditions were optimized. The as-prepared catalysts were characterized by BET, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Resonance (FT-IR), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy of adsorbed pyridine (Py-IR) and temperature-programmed desorption of NH3 (NH3-TPD). ZnO added ZrO2–SiO2 catalysts show the best catalytic activity and the catalysts prepared by the hybrid sol–gel method were superior to those prepared by the sol–gel coupled with impregnation method. The addition of promoters in the ZrO2–SiO2 system decreased the total acidity and lowered the selectivity to dehydration products. The best performance with ethanol/acetaldehyde conversion of 40.7% and 1,3-butadiene selectivity of 83.3% was reached at 310 °C, ethanol/acetaldehyde mole ratio of 3.5 and WHSV of 1.4 h−1 using a 0.5 wt% ZnO doped ZrO2–SiO2 catalyst.
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SENSORS AND ACTUATORS B-CHEMICAL
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2024
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IF 8
Xin-He Duan,Hong-Wei Li,Yi Li,Zhijiu Huang,Sha Liu,Yuqing Wu
Acetaldehyde (AH) is defined as a carcinogen, the widely existence in alcoholic beverages has led its determination an essential aspect related to human health. Fluorine doped carbon dots (dF-CDs) is developed, which process light-activated oxidase-mimic property and high stability at acidic condition. Under the UV irradiation, dF-CDs generate reactive oxygen species (ROS) to oxidize o -phenylenediamine (OPD) into 2,3-diaminophenazine (DAP), showing absorption peak at 450 nm and strong emission at 577 nm, meanwhile, the produced DAP quenches the original emission of dF-CDs at 455 nm via an inner filter effect (IFE). However, the introduction of AH inhibits such processes efficiently, thereby establishing a colorimetry and ratiometric fluorescence method for AH determination. Of note, this dual-responsive method has been used for the accurate AH determination in Chinese Baijiu . Therefore, the developed method not only provide a dual-sensing platform to determine AH, but also extends the applications of CDs in food analysis.
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FUEL
·
2024
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IF 6.7
Yuan Liu,Fang Liu,Li Yang,Feiqiang Guo,Shiliang Wu,Rui Xiao
The work introduced an innovative pathway for converting biomass-derived carbonyls into long-chain ethers, examining their low-temperature oxidation in a modified Cooperative Fuel Research (CFR) engine. The conversion of 2-butanone achieved 100 % and the selectivity of sec -butyl isopropyl ether reached the maximum of 83.13 % under optimal reaction conditions. Conversion of biomass-derived carbonyls increased from 31.77 % at 1 h to 36.28 % at 12 h, with the mass yield of long-chain ethers rising from 53.94 % to 62.86 %. At the same compression ratio, the maximum in-cylinder pressure and temperature increased as the long-chain ethers blending ratio increased. At the critical compression ratio, the net heat release rates (NHR) for blended fuels with 10 vol%, 20 vol% and 30 vol% long-chain ethers at the low-temperature heat release peak were 9.6 J/deg, 10.1 J/deg, and 10.0 J/deg better than that of n -heptane (6.3 J/deg), respectively. CO emissions from blended fuels before compression ignition were higher than n -heptane, while the value for the blended fuel with 30 vol.% long-chain ethers was reduced by 44.97 % compared to n -heptane after autoignition.
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JOURNAL OF RARE EARTHS
·
2025
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IF 7.2
Yan Liang,Hua Tang,Chunbo Ru,Xiaojian Zhao,Lu Tang,Yong Yang
Nanostructured materials with small particle sizes have been widely used in resistive gas sensors due to their high specific surface area and surface activity. However, phenomena including agglomeration, growth and structural damage of nanostructures are almost inevitable during the processes of device fabrication or sensing tests, which makes it difficult to exert their expected activity. To address this issue, rare earth metal oxide CeO 2 was chosen as the model material to explore confined nanostructures in resistive gas sensors. The experiment successfully achieves the preparation of confined CeO 2 nanoparticles film using a pulsed laser deposition combined with rapid annealing technology. It is found that the confined CeO 2 nanoparticles film enables the efficient detection of volatile organic compound triethylamine, demonstrating a significant response of 20 ( R a / R g ) towards 100 ppm triethylamine, a fast response of 2 s, excellent stability and selectivity. By in-situ confinement in porous carbon matrix, dispersion and fixation of CeO 2 nanoparticles can be achieved, thereby fully utilizing their high surface activity. In addition, the porous carbon matrix can serve as a transport pathway for the target gas molecules and electrons, enabling efficient gas-solid reactions and effective collection of gas sensing signals. More importantly, the confined CeO 2 nanoparticles film was grown in-situ on commercial alumina flats gas sensing substrate, which can be directly used as sensing layer for gas sensors. Based on first-principles calculations, the triethylamine sensing mechanism of the confined CeO 2 nanoparticles film was systematically analyzed at the atomic and electronic scale. This study offers new insights into enhancing the gas sensing performance of resistive gas sensors through confined nanostructures design.
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