Food Analytical Methods
·
2015
·Vol. 9
·期 5
·1188-1198
·
IF 1.956
Xu Yong-Quan,Wang Chao,Li Chang-Wen,Liu Shun-Hang,Zhang Chen-Xia,Li Li-Wei,Jiang Dong-Hua
Aroma volatiles from ripened and raw pu-erh tea were extracted by headspace solid-phase microextraction (HS-SPME) and simultaneous distillation-extraction (SDE). They were then characterized and identified using gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). The conditions of HS-SPME including fiber selections and sampling condition optimization have been previously investigated. With the two methods, 39 and 33 aroma-active compounds were detected and characterized in ripened and raw pu-erh tea samples, respectively. The aroma-active compounds with similar sensory descriptors were grouped into the same category, and the sum of individual aroma intensity values within each category showed that the floral aroma (33.01 %), stale/musty aroma (25.24 %), and woody aroma (11.17 %) were the major aroma categories in ripened pu-erh tea. Alcohols ( floral aroma notes), methoxyphenolic compounds ( stale/musty aroma notes), and ketones ( woody or floral aroma notes) play a vital role in the special flavor of ripened pu-erh tea. In raw pu-erh tea, the floral aroma (38.62 %) and fruity aroma (16.55 %) were the major aroma categories. These aromas were closely related to the characteristics of raw pu-erh tea aroma and its sensory perception.
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高影响因子
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2019
·Vol. 125
·期 5
·1-9
·
IF 1.784
Feng Guyu,Wang Xinyue,Zhang Diantang,Xiao Xueliang,Qian Kun
The performance degradation of polypropylene (PP) fibers which induced by ultraviolet (UV) irradiation are commonly defect in service, especially in the outdoor environment. In this study, ZnO coated nano-TiO 2 with resistance in full range of UV irradiation is prepared by ultrasonic-microwave homogeneous precipitation method. The chemical structure, physical–chemical property, and atomic structure and surface morphology of the ZnO coated nano-TiO 2 are systematically investigated by FTIR, XRD, BET and TEM analysis. The uvioresistant PP fibers are prepared by melting blending method with PP and coated nano-TiO 2 as raw materials. The effect of coated nano-TiO 2 on UV resistance of PP fibers is described by carbonyl index, molecular weight and mechanical property. Results showed that PP fibers with coated nano-TiO 2 exhibited excellent UV shielding effect in full range of UV irradiation.
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高影响因子
TRANSACTIONS OF TIANJIN UNIVERSITY
·
2020
·Vol. 26
·期 6
·441-449
·
IF 0
Liu Guoliang,Zhang Chunhui,Liu Mengfei,Guo Ziwei,Wang Xinsheng,Yu Cunming,Cao Moyuan
Fundamental research and practical applications have examined the manipulation of gas bubbles on open surfaces in low-surface-tension, high-pressure, and high-acidity, -alkalinity, or -salinity environments. However, to the best of our knowledge, efficient and general approaches to achieve the smart manipulation of gas bubbles in these harsh environments are limited. Herein, a Fluorinert-infused shape-gradient slippery surface (FSSS) that could effectively regulate the behavior of gas bubbles in harsh environments was successfully fabricated. The unique capability of FSSS was mainly attributed to the properties of Fluorinert, which include chemical inertness and incompressibility. The shape-gradient morphology of FSSS could induce asymmetric driving forces to move gas bubbles directionally on open surfaces. Factors influencing gas bubble transport on FSSS, such as the apex angle of the slippery surface and the surface tension of the aqueous environment, were carefully investigated, and large apex angles were found to result in large initial transport velocities and short transport distances. Lowering the surface tension of the aqueous environment is unfavorable to bubble transport. Nevertheless, FSSS could transport gas bubbles in aqueous environments with surface tensions as low as 28.5 ± 0.1 mN/m, which is lower than that of many organic solvents (e.g., formamide, ethylene glycol, and dimethylformamide). In addition, FSSS could also realize the facile manipulation of gas bubbles in various aqueous environments, e.g., high pressure (~ 6.8 atm), high acidity (1 mol/L H 2 SO 4 ), high alkalinity (1 mol/L NaOH), and high salinity (1 mol/L NaCl). The current findings provide a source of knowledge and inspiration for studies on bubble-related interfacial phenomena and contribute to scientific and technological developments for controllable bubble manipulation in harsh environments.
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MICROCHIMICA ACTA
·
2017
·Vol. 184
·期 10
·3817-3823
·
IF 4.58
Li Jingjing,Wang Yuxian,Jiao Yunfei,Jia Ru,Chen Zhengbo
Under normal circumstances, chromate ions cannot oxidize core-shell Cu-Au nanoparticles (NPs) because the standard redox potential of the Cr(VI)/Cr(III) system is lower than that of Au(I)/Au. However, in the presence of a certain concentration of hydrogen bromide, the Nernst potential becomes higher than that of Au(I)/Au and Cu(II)/Cu (as calculated by the Nernst equation). Based on this finding, a colorimetric method was developed that is based on oxidative etching of Cu@Au NPs by chromate. The Cu-Au NPs have a light red color in the presence of 5 mM HBr. On addition of Cr(VI), the gold shell is rapidly etched from the surface of the Cu-Au NPs, and this is accompanied by a color change to blue. The color changes were characterized by UV-vis spectroscopy. The absorbance at 526 nm changes in the 0.4 nM to 1 μM chromate concentration range, and the detection limit is 0.21 nM.
Schematic of a highly sensitive and selective colorimetric method for detection of chromate based on the redox etching of Cu@Au nanoparticles induced by Cr(VI). The presence of HBr enables Cu@Au NPs to be oxidized by Cr 6+ .
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高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2022
·Vol. 29
·期 38
·57823-57834
·
IF 5.19
Yi Shuang,Bao Binqin,Song Weifeng,Liu MuDdan
In this study, L-methionine and nano-Fe 3 O 4 were encapsulated and cured on sodium alginate by the ionic cross-linking method to form magnetic composite gel spheres (SML) as an adsorbent for the removal of Zn(II) from water. The influence of adsorbent dosages, pH, reaction time, and initial ion concentration on the ability of the gel spheres to adsorb Zn(II) was investigated, and the adsorption mechanism was identified. The experimental results showed that under the optimum conditions (pH = 5, t = 60 min, dosage of SML is 0.7 g·L −1 ), the maximum amount of Zn(II) adsorbed by the adsorbent gel spheres reached 86.84 mgˑg −1 . The reaction process of this adsorbent fits well with the Langmuir and pseudo-second-order kinetic models and is a heat absorption reaction. The adsorbent would preferentially adsorb Pb(II), and the adsorption efficiency of Zn(II) decreased when the concentration of interfering ions increased in the coexistence system. Further mechanistic research showed that this magnetic composite adsorbent is a mesoporous material with superior adsorption performance, and the amino and carboxyl groups on it react with Zn(II) via ligand chelation; the ion exchange effect of Ca(II) also plays a role. The adsorption amount of Zn(II) was maintained at a higher level after 5 cycles, and the loss of Fe was approximately 0.2%. In summary, SML, which is environmentally friendly, efficient, and recyclable, is an ideal adsorbent for Zn(II) removal.
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DOI
PubMed
高影响因子
JOURNAL OF SOLUTION CHEMISTRY
·
2022
·Vol. 51
·期 12
·1508-1521
·
IF 2
Wei Mengru,Wu Yuxing,Li Tiancheng,Zhang Ping,Liu Xuejun,Zhai Cuiping,Chen Xin
Cyclic voltammetry (CV), 1 H nuclear magnetic resonance ( 1 H NMR), density functional theory (DFT), quantum theory of atoms in molecules (QTAIM) and reduced density gradient (RDG) were used to study the interactions of dopamine hydrochloride (DH) with nicotinic acid (NAC) in aqueous solution. The results revealed that there existed three weak interactions in the DH–NAC system, C–H···π, π···π stacking and hydrogen bonds. These interactions showed different effects on the DH electrooxidation and its chemical environment. Moreover, the CV and 1 H NMR results indicated that C–H···π interaction between the H atoms on the benzene ring of DH and the pyridine ring of NAC, and π···π stacking between the benzene ring of DH and the pyridine ring of NAC are the main interactions in the system.
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高影响因子
Bioresources and Bioprocessing
·
2018
·Vol. 5
·期 1
·1-8
·
IF 0
Gao Zhen,Yi Yunfei,Zhao Jia,Xia Yongyang,Jiang Min,Cao Fei,Zhou Hua,Wei Ping,Jia Honghua,Yong Xiaoyu
Background Laccase, a multicopper oxidase that catalyzes the oxidation of phenols, aromatic amines, and benzenethiols, has attracted much attention in applications of organic synthesis, bioremediation, and pulp/textile bleaching. However, free laccases cannot be recycled and are easily inactivated in diverse environmental conditions. Enzyme immobilization is a promising strategy to improve stability, resistance to extreme conditions, and reusability of laccase. Results In this study, amino-functionalized magnetic Fe 3 O 4 nanoparticles were synthesized for co-immobilization of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and laccase by glutaraldehyde cross-linking method. The magnetic nanoparticles were characterized with FTIR, XRD and VSM. Cyclic voltammetry was carried out to verify electrochemical behaviors of the co-immobilized laccase and TEMPO nanoparticles. When the co-immobilized laccase and TEMPO nanoparticles were used to decolorize acid fuchsin, the maximum decolorization rate of 77.41% was obtained with the ratio of TEMPO to laccase being 0.3 mM/g:120 U/g. Conclusion The co-immobilized nanoparticles retained above 50% residual activity after eight cycles of operation, which presented an approach to develop a co-immobilized laccase and mediator system for potential industrial application.
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CELLULOSE
·
2018
·Vol. 25
·期 10
·5511-5522
·
IF 3.809
Li Xingkang,Luo Yifan,Daroch Maurycy,Hou Juan,Gui Weiyang
Hemicellulose and lignin act as physical barriers impeding the hydrolysis of lignocellulosic biomass by cellulases. To develop a process which could simultaneously remove most hemicellulose and lignin in biomass, in this study, oxygen-assisted ethanol organosolv pretreatment (O 2 -EOP) of sugarcane bagasse (SCB) was carried out. The effects of temperature, time, oxygen pressure and ethanol concentration on the pH of the hydrolysate, the solubilization and the chemical composition of SCB were investigated. Compared with autocatalytic EOP and acid-catalyzed EOP, O 2 -EOP could remove most xylan and lignin from SCB at much milder conditions. At optimized conditions (40/60 ethanol/water (v/v), 1.5 MPa O 2 , 160 °C and 80 min), 82.9% xylan and 83.3% lignin were removed. Glucan content in the residue reached 86.3%, much higher than results obtained by autocatalytic EOP and acid-catalyzed EOP. In subsequent enzymatic hydrolysis (1% solid loading, 4.96 mg protein/g cellulose, 72 h), O 2 -EOP pretreated SCB produced 3.97 and 1.90 times more glucose than untreated material and N 2 -EOP pretreated SCB, respectively. O 2 -EOP also produced abundant organic acids, total amounts of formic acid and acetic acid in the hemicellulose hydrolysate reached 5.42 g/L. In conclusion, O 2 -assisted EOP was an effective process for the production of pulp with high cellulose purity and good accessibility to cellulases.
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高影响因子
IONICS
·
2019
·Vol. 25
·期 7
·3143-3152
·
IF 2.289
Li Jie,Lei Xiaoke,Qin Furong,Zong Chuanxin,Liu Lele,Zhang Kai
MoSe 2 nanosheets embedded in a mesoporous carbon matrix is synthesized through a facile route, where molybdenum source is recrystallized forming nanocrystals and further react with selenium. To obtain fine nanocrystals, freeze-drying technique is used to creating a large subcooled temperature. With low MoSe 2 content of ~ 54 wt%, the mesoporous MoSe 2 /C composite shows an initial capacity of 450 mA h g −1 and a reversible capacity of 276 mA h g −1 after 200 cycles.
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高影响因子
JOURNAL OF POLYMER RESEARCH
·
2013
·Vol. 20
·期 8
·1-6
·
IF 2.019
Li Chunfang,Li Dongxiang,Qiu Chuanlong,Hou Wanguo
Amphiphilic dendritic macromolecules are suitable for the noncovalent encapsulation of guest molecules and could potentially be applied in drug-delivery systems. In this work, amphiphilic carbosilane dendrimers with peripheral poly(ethylene glycol) (PEG) units were synthesized using a hydrosilylation reaction, and their encapsulation properties were studied by fluorescence spectroscopy, using pyrene as the probe molecule. The results showed that the encapsulating capacity of the dendrimers increased as the number of PEG units increased, and that it also depended to some degree on the dendrimer generation.
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高影响因子
Frontiers of Materials Science
·
2016
·Vol. 10
·期 2
·113-121
·
IF 1.354
Wei Qilin,Xu Feiyang,Xu Xingjian,Geng Xue,Ye Lin,Zhang Aiying,Feng Zengguo
The non-woven wound dressing with core–shell structured fibers was prepared by coaxial electrospinning. The polycaprolactone (PCL) was electrospun as the fiber’s core to provide mechanical strength whereas collagen was fabricated into the shell in order to utilize its good biocompatibility. Simultaneously, the silver nanoparticles (Ag-NPs) as anti-bacterial agent were loaded in the shell whereas the vitamin A palmitate (VA) as healing-promoting drug was encapsulated in the core. Resulting from the fiber’s core–shell structure, the VA released from the core and Ag-NPs present in the shell can endow the dressing both heal-promoting and anti-bacteria ability simultaneously, which can greatly enhance the dressing’s clinical therapeutic effect. The dressing can maintain high swelling ratio of 190% for 3 d indicating its potential application as wet dressing. Furthermore, the dressing’s anti-bacteria ability against Staphylococcus aureus was proved by in vitro anti-bacteria test. The in vitro drug release test showed the sustainable release of VA within 72 h, while the cell attachment showed L929 cells can well attach on the dressing indicating its good biocompatibility. In conclusion, the fabricated nanofibrous dressing possesses multiple functions to benefit wound healing and shows promising potential for clinical application.
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高影响因子
International Journal of Environmental Science and Technology
·
2018
·Vol. 16
·期 10
·5669-5684
·
IF 2.037
Zhou H.,Chen X.,Ying T.,Xuan Y.,Wangjin Y.,Liu X.
Thirteen wastewater-marking pharmaceuticals were selected to explore their variations and behavior under hydrodynamic conditions in urban river systems. Four flow velocities were set, i.e., 0 cm/s for static condition, and 5, 10 and 20 cm/s for dynamic conditions. In the water phase, most of target compounds emerged big fluctuations between static and dynamic conditions. The lower concentrations were detected in the dynamic conditions. However, carbamazepine had minimum relative change during the whole 15-day tests with at least 85% of the initial concentration remaining. In the sediment, the concentrations of most pharmaceuticals in the dynamic conditions were higher than in the static condition, whereas carbamazepine showed big fluctuation in both static and dynamic conditions. With the change of the flow velocities, all target pharmaceuticals showed obviously different variation tendencies mainly due to the changes of environmental parameters, such as turbidity, dissolved matters, microbial biomass, and suspended particulates. In addition, five metabolites were selected to further investigate the transformation of diclofenac and carbamazepine with different flow velocities in the water phase. More diclofenac were transformed into 4-Hydroxy diclofenac in the water phase in the dynamic conditions. Moreover, in the case of a set flow velocity, the concentrations of some pharmaceuticals changed remarkably between the straight and turning channels of an urban river system. Overall, hydrodynamic conditions showed significant influences on the levels of target compounds in the aquatic environment and, therefore, could be taken into account in the risk assessment and control of these compounds.
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高影响因子
危险品化学品经营许可证（带存储）