Scientific Reports
·
2015
·Vol. 5
·期 1
·1-6
·
IF 5.578
Yao Feng,Yi Bin,Shen Caihong,Tao Fei,Liu Yumin,Lin Zhixin,Xu Ping
Luzhoulaojiao liquor is a type of Chinese liquor that dates back hundreds of years, but whose precise chemical composition remains unknown. This paper describes the screening of the liquor and the identification of its compounds using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC/TOF-MS). Samples were prepared by both liquid-liquid extraction and solid-phase microextraction, which facilitated the detection of thousands of compounds in the liquor, thus demonstrating the superior performance of the proposed method over those reported in previous studies. A total of 320 compounds were common to all 18 types of Luzhoulaojiao liquor studied here and 13 abundant and potentially bioactive compounds were further quantified. The results indicated that the high-performance method presented here is well suited for the detection and identification of compounds in liquors. This study also contributes to enriching our knowledge of the contents of Chinese liquors.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Analytical Methods
·
2013
·Vol. 5
·期 19
·5037-5043
·
IF 1.855
Yingtang Li,Yang Jiao,Yuhong Guo,Yaling Yang
A new and fast microextraction technique termed vortex-assisted supramolecular solvent microextraction (VASUSME) has been developed. The method was based on the microextraction of endocrine disrupting compounds (EDCs), including bisphenol-A (BPA), 2,4-dichlorophenol (2,4-DCP), bisphenol-AF (BPAF) and tetrabromobisphenol-A (TBBPA) in 10 mL sample with 500 μL of a supramolecular solvent (SUPRASs), and then detection by high-performance liquid chromatography (HPLC). In the VASUSME procedure, dispersion of microvolumes of a low density extraction solvent into the aqueous sample is achieved by vortex mixing, a mild emulsification procedure. Under the optimum conditions, the repeatability of the proposed method was found to be good. The relative standard deviations (RSD, n = 5) were 3.98–5.64%. The limits of detection (LOD) were in the range of 0.14–0.32 ng mL−1 and the limits of quantification (LOQ) were in the range of 0.41–1.02 ng mL−1. All correlation coefficients of the calibration curves were higher than 0.998. Recoveries of the EDCs spiked into samples of liquid foods and their packaging materials were in the range of 91% to 105.1%. The VASSUSME method was successfully applied to the analysis of BPA, 2,4-DCP, BPAF and TBBPA in samples of liquid foods and their packaging materials. Moreover, the method is simple, sensitive and environmentally-friendly and consumes much less solvent than traditional methods.
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
·
2015
·Vol. 16
·期 4
·7273-7288
·
IF 2.862
Dongming Lan,Qian Wang,Jinxin Xu,Pengfei Zhou,Bo Yang,Yonghua Wang
Thermostability and substrate specificity are important characteristics of enzymes for industrial application, which can be improved by protein engineering. SMG1 lipase fromMalassezia globosais a mono- and diacylglycerol lipase (MDL) that shows activity toward mono- and diacylglycerols, but no activity toward triacylglycerols. SMG1 lipase is considered a potential biocatalyst applied in oil/fat modification and its crystal structure revealed that an interesting residue-Asn277 may contribute to stabilize loop 273–278 and the 3104 helix which are important to enzyme characterization. In this study, to explore its role in affecting the stability and catalytic activity, mutagenesis of N277 with Asp (D), Val (V), Leu (L) and Phe (F) was conducted. Circular dichroism (CD) spectral analysis and half-life measurement showed that the N277D mutant has better thermostability. The melting temperature and half-life of the N277D mutant were 56.6 °C and 187 min, respectively, while that was 54.6 °C and 121 min for SMG1 wild type (WT). Biochemical characterization of SMG1 mutants were carried out to test whether catalytic properties were affected by mutagenesis. N277D had similar enzymatic properties as SMG1 WT, but N277F showed a different substrate selectivity profile as compared to other SMG1 mutants. Analysis of the SMG1 3D model suggested that N277D formed a salt bridge via its negative charged carboxyl group with a positively charged guanidino group of R227, which might contribute to confer N277D higher temperature stability. These findings not only provide some clues to understand the molecular basis of the lipase structure/function relationship but also lay the framework for engineering suitable MDL lipases for industrial applications.Keywords:mono- and diacylglycerol lipase;thermostability;substrate selectivity;site-directed mutagenesis
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE
·
2014
·Vol. 95
·期 5
·915-921
·
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
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ANALYTICAL AND BIOANALYTICAL CHEMISTRY
·
2017
·Vol. 409
·期 30
·7063-7075
·
IF 3.431
Wang Meng,Jiao Yang,Cheng Chunsheng,Hua Jianhao,Yang Yaling
A novel and sensitive method based on nitrogen-doped carbon quantum dots as a fluorescence probe coupled with magnetic solid-phase extraction (MSPE) purification for analysis of folic acid (FA) in human serum samples has been established for the first time. In the developed system, magnetic nanoparticles coated with hexanoic acid (Fe 3 O 4 @C 6 ) were synthesized by a one-step chemical co-precipitation method with good magnetic properties and dispersibility for sample purification, and it is better to be separated from the sample. High fluorescence nitrogen-doped carbon quantum dots (N-CQDs), simply prepared using a one-step hydrothermal method with nitrilotriacetic acid, could be selectively quenched by FA. Based on this phenomenon, a fluorescence assay was proposed for specific determination of FA. Various operational experiment parameters have been studied and optimized in detail. Under the optimum experimental conditions, the detection limit of the proposed method for FA was evaluated to be 0.5 nM (S/ N = 3), while the relative standard deviation (RSD) was 1.2% ( n = 6). Finally, the proposed method was applied for determination of trace levels of FA from human serum samples and quantitative recoveries were achieved within the range of 95.7–103.5%. All of the results showed that the proposed method had significant application in further research.
Schematic of synthesis of N-CQDs and schematic of suggested mode for analysis of folic acid (FA).
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2017
·Vol. 55
·期 13
·2211-2220
·
IF 2.952
Yuchen Feng,Suyun Jie,Bo-Geng Li
Fatty acid-derived cyclooctenes, including n -hexanoic acid ( M1 ), n -octanoic acid ( M2 ), lauric acid ( M3 ), and palmitic acid ( M4 ), were prepared as monomers and polymerized by ring-opening metathesis polymerization (ROMP) using Grubbs second-generation catalyst ( G2 ). In all the cases, the regio-irregular unsaturated polymers with pendent linear branches were obtained, which could be saturated by chemical hydrogenation with TSH/TPA in high conversion, yielding ethylene/vinyl ester copolymers with pendent linear branches on precisely every eighth backbone carbon. Both unsaturated and saturated polymers were amorphous, and their structures were characterized by FTIR, 1 H and 13 C NMR spectra, and elemental analysis. Differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA) were used to study their thermal properties. The chain length of branches greatly affected the thermal properties of polymers. After hydrogenation, the thermal degradation stability of polymers was relatively improved. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 2211–2220
✓ 已验证
产品关联
DOI
高影响因子
PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION
·
2017
·Vol. 34
·期 7
·1700117
·
IF 4.474
Yanning Qu,Renliang Huang,Wei Qi,Qi Qu,Rongxin Su,Zhimin He
Encapsulation of enzymes with enhanced activity and recyclability in water-in-oil Pickering emulsions is a simple and efficient method for their immobilization; however, the effect produced by the structure of colloidal particles on the stabilization of the Pickering emulsion for enzyme catalysis has not been investigated in detail. In this study, four types of hydrophobic Fe 3 O 4 @SiO 2 nanoparticles (NPs) with similar chemical compositions, particle diameters, but different surface characteristics have been prepared and utilized for enzyme encapsulation in various water-in-oil magnetic Pickering emulsions, after which the relationship between NPs structure, size of emulsions droplets, and enzyme activity is examined. The obtained results indicate that (i) the more hydrophobic Fe 3 O 4 @SiO 2 NPs cause the higher enzyme activity; (ii) the higher hydrophobicity of oil phase also increases the enzyme activity, especially for Fe 3 O 4 @w-SiO 2 NPs which form in the solvent of water. The results are mainly attributed to the higher specific surface area of emulsion droplets and interfacial mass transfer of substrates through the interfaces of droplets. The reported data provide new insights into the mechanism of stabilization of Pickering emulsions for enhancing enzyme activity and demonstrate efficient theoretical references for enzyme immobilization and synthesis of stable and active biocatalysts with high recyclability.
✓ 已验证
产品关联
DOI
高影响因子
Journal of Coatings Technology and Research
·
2017
·Vol. 14
·期 3
·505-516
·
IF 1.557
Huang Shan,Xiao Juan,Zhu Yan’an,Qu Jinqing
A series of multiarm star hydroxyl-terminated polyesters (MHPs) were synthesized through a “one-pot” method with di-trimethylolpropane as the core molecule, 2,2-dimethylolpropionic acid as the AB 2 -type monomer, ε-caprolactone, and monocarboxylic acids as modifiers. The influence of different monocarboxylic acids on the viscosities of polyesters and their 2K-PU films hardness was studied and it was found that MHPs prepared from lauric acid displayed the higher films hardness and lower viscosities. IR spectra of MHPs disclosed the ring-opening reaction between ε-caprolactone and hydroxyl groups occurred. 1 H NMR spectra demonstrated that the molecular structures of MHPs were irregular due to the multiplicity of reaction processes. The measured number-average molecular weights ( M
n ) of MHPs were around 715–1854 g/mol with the PDI of 1.45–2.05. MHPs exhibited lower viscosities in the range of 3304–9060 mPa s at 100% solid contents and possessed lower intrinsic viscosities compared with linear polymers of similar molecular weight. The cured films of MHPs exhibited excellent impact resistance, adhesion, flexibility, and high hardness and displayed good thermal stability with 5% weight loss at 280°C. The solution viscosities of MHPs were less than 450 mPa s at 80% solid contents, and the VOC contents of 2K-PU coatings obtained from MHPs were low to 300 g/L.
✓ 已验证
产品关联
DOI
高影响因子
CHEMISTRY OF MATERIALS
·
2017
·
IF 9.466
Aifei Wang,Yanyan Guo,Faheem Muhammad,Zhengtao Deng
Hollow nanocrystals have attracted considerable attention in many areas of materials science because of their unique geometry, large surface area, high loading capacity and low density, and potential applications in catalysis, energy storage, drug delivery, and molecular separation. So far, numerous hollow nanostructured materials, such as noble metals, metallic oxides, hydroxides, and chalcogenides, have been reported. However, there is no report about the hollow metal halide perovskite nanocrystals yet. Herein, for the first time, we report the controlled synthesis of metal halide perovskite hollow nanocrystals, i.e., CsSnBr3 cubic nanocages, through a facile hot-injection colloidal approach. The formation of nanocages was controlled by rationally choosing the precursors and reaction temperature and was achieved through the self-assembly driven process. The as-synthesized CsSnBr3 nanocages exhibit excellent oxygen resistibility under desiccation conditions. Furthermore, treatment of CsSnBr3 nanocages with perfluorooctanoic acid results in an improved stability against moisture, oxygen, and light. This work represents a step toward hollow nanocrystals of metal halide perovskites for optical, electronic, and optoelectronic applications.
✓ 已验证
产品关联
DOI
高影响因子
LANGMUIR
·
2017
·
IF 3.833
Jinghui Wang,Renliang Huang,Wei Qi,Rongxin Su,Zhimin He
Enzyme-loaded water-in-oil Pickering emulsion is a promising system for biphasic catalytic reactions. In this paper, we report on oriented enzyme immobilization at the oil/water interface in a Pickering emulsion, in which CHO-Janus silica nanoparticles (CHO-JNPs) are utilized as a stabilizer of the emulsion and support for the enzyme to enhance both catalytic activity and recyclability. The catalytic performance of this immobilized enzyme (lipase from Candida sp.) was evaluated by esterification of hexanoic acid and 1-hexanol in a water/heptane biphasic medium. The results show that the specific catalytic activity of the immobilized enzyme (33.2 U mL–1) was 6.5 and 1.4 times higher than that of free enzyme (5.1 U mL–1) and encapsulated enzyme in the liquid core (23.3 U mL–1), respectively. Moreover, the immobilized enzyme demonstrated good stability and recyclability, retaining 75% of its activity after 9 cycles. We expect that oriented enzyme immobilization at the oil/water interface will be an important strategy for enhancing catalytic performance in Pickering emulsions.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
BIOCATALYSIS AND BIOTRANSFORMATION
·
2016
·
IF 0.892
Danping Qi,Wei Wei,Mingming Diao,Fengxia Lv,Zhaoxin Lu,Xiaomei Bie,Haizhen Zhao
Lipase-catalyzed synthesis of mono- and diesters of 3-O-β-D-galactopyranosyl-sn- glycerol (β-GG) with caproic acid was performed in acetone. The simultaneous production of 1(6’)-monoesters and 1,6’-diesters of β-GG was achieved in this reaction. In order to improve the yield of β-GG esters, four process parameters, enzyme concentration (15 ∼ 25 mg/mL), and substrate molar ratio (caproic acid: β-GG= 1.60 ∼ 2.00 mmol: 0.10 mmol), reaction temperature (40 ∼ 60 °C), and reaction time (8 ∼ 12 h), were optimized via response surface methodology (RSM) employing a three-level-four-variable central composite design. Results showed that enzyme concentration had the most significant (p < 0.0001) effect on the synthesis of β-GG esters. The optimal reaction conditions in acetone were given as follows: Novozyme435 concentration 18.65 mg/mL, molar rate of caproic acid to β-GG 19.46:1, reaction temperature 48 °C, and reaction time 9.83 h. The yield of β-GG esters reached 88.08% under above optimized conditions, which was very close to the predicted value 87.95%. The molar ratio of monoester to diesters was 0.39:0.61. β-GG esters with other fatty acyl chains were synthesized based on the optimized conditions. In vitro antitumor activity indicated that the antitumor activity of β-GG esters was dependent on the nature of fatty acids, such as the length of acyl chain, the degree of saturation, as well as the number of acyl chain.
✓ 已验证
产品关联
DOI
高影响因子
Energy Technology
·
2017
·Vol. 5
·期 8
·1195-1199
·
IF 2.789
Yuanhao Cai,Yulong Chen,Qijie Li,Liang Li,Haoxin Huang,Suying Wang,Weixing Wang
We demonstrate that l -methionine, a natural amino acid, can be used to dramatically enhance CO 2 uptake kinetics in the formation of CO 2 hydrate without the use of energy-intensive mixing technologies or environmentally harmful chemicals. To the best of our knowledge, l -methionine is the most effective promoter to enhance CO 2 hydrate formation (at a concentration of 0.2 wt %, the gravimetric capacity reached up to 356 mg g −1 in 1000 min, and t 90 (the time to achieve 90 % of this capacity) was only 15 min). We also present a tentative explanation for the promotion mechanism of l -methionine in the formation of CO 2 hydrate from the point of view of structure–property relationship that will help search for more effective promoters. Our results may offer the possibility of practical application of hydrate-based CO 2 capture and storage technology.
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）