FOOD CHEMISTRY
·
2019
·
IF 5.399
Gaigai Li,Xufeng Meng,Junmin Wang,Qianqian Wang,Junhong Zhou,Chun Wang,Qiuhua Wu,Zhi Wang
In this study, a porous organic polymer (denoted as Car-DMB) was fabricated by a simple one-step crosslinking polymerization of carbazole and p -dimethoxybenzene for the first time. Then the Car-DMB was served as adsorbent of solid phase extraction to enrich triazine herbicides from white gourd, tomato and soybean milk samples prior to their determination by high performance liquid chromatography. Under the optimal conditions, the response linearity was in the range of 0.3–100.0 ng g −1 for white gourds and tomato samples, and 0.5–100.0 ng mL −1 for soybean milk, with the coefficient of determination higher than 0.996. The detection limits were 0.1–0.2 ng g −1 for white gourd and tomato samples, and 0.15–0.3 ng mL −1 for soybean milk. The adsorption mechanism of the Car-DMB for the triazines was attributed to the strong H-bonding and weak π-π interactions. The efficient extraction for several other compounds demonstrated that Car-DMB holds great potential for diverse analysis applications.
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SCIENTIA HORTICULTURAE
·
2019
·
IF 1.961
Yonghong Ge,Junhu Zhang,Canying Li,Wenjun Xue,Shiyu Zhang,Jingyi Lv
The purpose of this study was to evaluate the effects of trisodium phosphate (TSP) (0.5 g L −1 ) treatment on softening of harvested jujube fruit during storage at 20 ± 2 °C with a relative humidity of 50–55 %. The results showed that jujube fruit treated with TSP showed a higher firmness. The activity of pectin methylesteras, polygalacturonase, cellulase and β-glucosidase was also suppressed by TSP treatment. The results demonstrated that the content of water soluble pectin in jujube fruit treated with TSP was lower than in the control (dipped in distilled water) during storage. TSP treated fruits had higher pectin content than control fruits. The results of atomic force microscopy showed that water soluble pectin structure treated by TSP was denser compared with the control. Taken together, these results demonstrated that TSP could delay softening of jujube fruit by regulating cell wall-degrading enzymes activities and controlling the pectin substances.
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Materials Research Express
·
2019
·Vol. 6
·期 6
·065405
·
IF 1.449
Qinghong You,Miaomiao Wan,Xiaoxu Fang,Xiulian Yin,Chuping Luo,Xuejuan Zhang
The process of intermittent microwave extraction (IME) pectin from pomelo peels assisted with EDTA was optimized by response surface methodology. Results showed that the optimal process for intermittent microwave extraction of pectin was as follows: 0.25% EDTA, pH 1.0, solid-to-liquid ratio 1:25 g ml−1, extraction time 125 s, microwave power 550 W, the extraction yield of pomelo peels was (38.48 ± 0.28)%. The structure of three kinds of pectin was verified by IR, SEM, XRD, HPLC and the results showed that pectin obtained from IME had a poor solubility but a good emulsifying activity. The IUEP had the highest scavenging rates of DPPH radicals.
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MATERIALS CHEMISTRY AND PHYSICS
·
2020
·
IF 3.408
Hanjun Zhang,Furong Tao,Yuezhi Cui,Hongtao Wu
Fluorescent conjugated polymers are widely used for trace detection of explosives due to their super-quenching effect. In this work, a hyper-branched conjugated polymer P2 and a linear conjugated polymer P1 were synthesized. Compared with P1, P2 showed the superior sensitivity toward 2,4,6-trinitrophenol (PA). The Stern-Volmer constants ( K sv ) of P2 (1.56 × 10 4 M −1 ) was 2.7 times higher than that of P1 (0.57 × 10 4 M −1 ), and the LODs to PA of P2 (8.8 μM) was 3.2 times lower than that of P1 (24 μM). These data indicated the enhanced super-quenching effect in P2. Due to the electrons transfer among the conjugated backbone of polymer, the super-quenching effect of P1 with one-dimensional (1D) configuration may be defined as “length quenching”, while that of P2 with two-dimensional (2D) configuration can be defined as “Area quenching”. The 2D conjugation nature of P2 provided multi migration channel for excitons , which resulted in the remarkably enhanced super-quenching.
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JOURNAL OF FOOD BIOCHEMISTRY
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2020
·Vol. 44
·期 3
·e13141
·
IF 1.662
Canying Li,Junhu Zhang,Yonghong Ge,Xiaoyan Li,Meilin Wei,Jiabao Hou,Yuan Cheng,Jingyi Lv
“Golden delicious” apples were dipped in 100 mg/L acibenzolar-S-methyl (ASM) to investigate the fruit quality and softening during 12 days of storage. Weight loss, flesh firmness, ethylene release, respiratory rate, content of total soluble solids and titratable acid, the activity of pectinase, cellulase, and β-glucosidase, and water-insoluble pectin and water-soluble pectin contents were investigated. The results demonstrated that ASM treatment inhibited ethylene release and respiratory rate, reduced titratable acidity, and enhanced total soluble solids content in apples. Moreover, application of ASM suppressed the reduction of flesh firmness, activity of pectin methylesterase, and polygalacturonase. Cellulase, β-glucosidase, and degradation of protopectin in apple fruit were also suppressed by ASM treatment during storage. In conclusion, ASM could maintain fruit quality by regulating cell wall-degrading enzymes during storage. Practical applications Application of acibenzolar-S-methyl after harvest has the potential of delaying fruit softening by regulating cell wall-degrading enzymes, thus retain fruit quality.
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JOURNAL OF FOOD PROCESSING AND PRESERVATION
·
2019
·Vol. 43
·期 12
·e14277
·
IF 1.288
Xiao Gong,Xiaobing Huang,Taohua Yang,Jing Wen,Wei Zhou,Jihua Li
The effects of hot air drying (HD), freeze-drying (FD), microwave drying (MWD), natural convective drying (NCD), and vacuum drying (VD) on the physicochemical, nutritional, and antioxidant properties of okra pods were investigated. Changes in the surface morphology, color, rehydration ratio, protein, pectin, ascorbic acid, and phenolics, as well as antioxidant activities of okra pods measured by 2,2′-azinobis (3-ethylbenzo thiazoline-6-sulphonic acid) diammonium salt (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and Ferric Ion Reducing Antioxidant Power (FRAP) assays were evaluated. In general, FD products exhibited a better retention of the texture characteristics, nutritional, and antioxidant activities, and was suitable for okra pods drying, although FD was the longer time-consuming method among the five drying methods. Furthermore, NCD products were poorer in color, texture, and nutrition. Future studies should continuously focus on various combinations of different types of drying methods to supply okra pods products with the most affordable cost and the highest quality. Practical applications Physicochemical properties and antioxidant capacities of okra pods are affected by the drying process. The drying process with nonthermal, low temperature, and low content of oxygen is beneficial to the retention of nutrients and functional components. In general, freeze-drying exhibited a better texture characteristics and good antioxidant activities, although higher energy and longer time consumption was the current challenge. How to combine the different types of drying methods has become an inevitable trend and research focus.
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CHINESE JOURNAL OF ANALYTICAL CHEMISTRY
·
2019
·
IF 0.931
Li-Ting NIU,Gen-Gen LI,Hai-Feng LI,Fan CUI,Jing ZHANG,Ying HUANG,Kai CHEN,Jian-Fu ZHANG,Wen-Fei LI,Wei-Lu LIU
Genistein is an important isoflavone that has been widely used to prevent blood disease and cancer. In this work, a novel genistein electrochemical sensor was developed based on the composite of molecularly imprinted polymer (MIP) and carboxylated multiwalled carbon nanotubes (cMWCNTs). The MIP layer was electropolymerizated on the cMWCNTs modified electrode using carbazole as functional monomer and genistein as template molecule. The morphology and electrochemical performance of MIP/cMWCNTs were characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV), respectively. A series of experimental conditions were optimized, including the pH value of supporting electrolyte, electropolymerization potential range, molar ratio of functional monomers to template molecules, numbers of cycle, accumulation potential and accumulation time. Under the optimal conditions, the resulting electrochemical sensor (MIP/cMWCNTs/GCE) showed high performance, such as high sensitivity and selectivity towards genistein, a wide linear range (0.02–7.00 μM) and a low limit detection of 0.006 μM ( S / N = 3). The electrochemical sensor was applied to determination of genistein in tablets and human urine samples with satisfactory recoveries (97.9%–102.8%), and the accuracy of the sensor was demonstrated with the HPLC method.
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Polymers
·
2018
·Vol. 10
·期 9
·1007
·
IF 2.935
Linlin Qin,Linling Li,Ye Sha,Ziyu Wang,Dongshan Zhou,Wei Chen,Gi Xue
The critical overlap concentrationC*is an important concept in polymer solutions and is defined as the boundary between dilute and semidilute regimes. In this study, the chain conformational changes of polystyrene (PS) with both high (Mn= 200,000 Da) and low (Mn= 13,000 Da) molecular weights in cis-decalin were compared by intrachain fluorescence resonance energy transfer (FRET). The random labeling of donor and acceptor chromophores strategy was employed for long PS chains, whereas chain-end labeling was used for short PS chains. By monitoring the spectroscopic intensity ratio between acceptor and donor, the concentration dependence on chain conformation from dilute to semidilute solutions was determined. Both long and short chains exhibit a conformational transition concentration, above which the polymer chains begin to collapse with concentration significantly. Interestingly, for randomly labeled polymer long chains, such concentration is consistent withC*determined from the viscosity result, below which only slight conformational change of polymer chain takes place. However, for the chain-end labeled short chain, the conformational transition concentration takes place earlier thanC*, below which no significant polymer conformation change is observed.Keywords:polymer solution;conformational transition;critical overlap concentration;fluorescence;viscosity
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JOURNAL OF CHEMICAL THERMODYNAMICS
·
2018
·
IF 2.631
Suping Ding,Qiuxiang Yin,Wei Du,Xiaowei Sun,Guiping Li,Yafei Mao,Hongxun Hao
The separation of phenanthrene (PHE) and carbazole (CAR) has been a tough job since the formation of solid solutions. Development of new separation strategy for PHE-CAR mixture highly depends on their phase equilibrium behaviour. In this work, ternary phase diagrams of phenanthrene (PHE) and carbazole (CAR) in dimethylformamide (DMF), acetone, acetonitrile (MeCN) and toluene at T = 308.15 K under normal atmosphere were determined through wet residue method. It was found that PHE-rich solid solution α was formed in the particular composition range of PHE-end. On the contrary, no CAR-rich solid solution was formed in CAR-end. These results were further verified through powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC). Based on the ternary phase diagrams, a difference coefficient of solubility ( Ds ) was put forward to assist screening and evaluation of solvents for solution crystallization. Among the four tested solvents, toluene is the most suitable one for separating PHE-CAR mixture.
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SYNTHETIC METALS
·
2018
·
IF 2.526
Yaxin Zhang,Fuhan Liu,Yanjun Hou,Haijun Niu
Here, we synthesized four kinds of monomers of 3,6-dibromo-(N-phenyl)carbazole with different substituent group, DCB, DDC, DNC and DTC, respectively, and used 4-(3-bromo-9H-carbazol-9-yl)benzaldehyde to react with triphenylamine (TPA) unit and hydrazine hydrate unit, respectively, to obtain the other two monomers, BCB-TPA and BCB-HH. Six novel polymers coded as PDCB-DF, PDDC-DF, PDNC-DF, PDCB-DTC-DF, PBCB-TPA-DF and PBCB-HH-DF, were synthesized by Suzuki reactions of 2,2'-(9,9-dioctyl-9H-fluorene-2,7-diyl)bis(1,3,2-dioxaborinane) with the six kinds of monomers and their electrochemical and spectroelectrochemical properties were investigated. The polymers showed good solubility and film-forming ability. Flexible or robust films of them could be readily obtained via solution-casting. These polymers showed the onset temperatures in the range of 300–470 °C when the 10% weight loss of polymers. The polymer films showed high coloration efficiency (CE) (196-376 cm 2 ·C −1 ) and electrochromic stability. These properties illustrate that the polymers have great application prospect as electrochromic materials.
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Journal of Energy Chemistry
·
2015
·
IF 2.352
Feifei Sun,Yue An,Lecheng Lei,Fuying Wu,Jingke Zhu,Xingwang Zhang
Hydrogenation of carbazole and N-ethylcarbazole over Raney-Ni catalyst were realized in the temperature range of 393–503 K. 4[H] adduct dominated the hydrogenation products and the formation of 2[H] adduct was the rate-limiting step during the period, in which the conversion of carbazole was less than 40%. The hydrogenation process followed pseudo-first-order kinetics and the hydrogenation activation energies of carbazole and N-ethylcarbazole were 90 kJ/mol and 115 kJ/mol, respectively. The reaction starting position as well as the pathway of the hydrogenation of (N-ethyl)carbazole were investigated by comparing the kinetic characteristics of hydrogen uptake of carbazole and N-ethylcarbazole. The results showed that the reaction was a stepwise hydrogenation process and the first H 2 was added to the C1 = C10 double bond in the hydrogenation.
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RSC Advances
·
2016
·Vol. 6
·期 20
·16467-16473
·
IF 3.289
Lanfang Pang,Yanmei Zhou,Enze Wang,Fang Yu,Hua Zhou,Wenli Gao
We have designed and synthesized a carbazole-based fluorescent probe (CZ-Nm) for the specific recognition of GSH over Cys and Hcy. The probe is almost non-fluorescent owing to the photoinduced electron transfer (PET) process from the carbazole fluorophore to the nitroolefin moiety. Upon treatment with GSH, owing to the Michael addition of GSH to the double bond of the nitroolefin moiety, the probe shows a fluorescence enhancement and absorption change. The CZ-Nm probe displays desirable properties such as acting as a “naked eye” probe, a wide linear range of 0–0.01 M, high sensitivity, and strong anti-jamming capability. More importantly, the probe can also be successfully applied to the detection of intracellular GSH with a bright fluorescence signal, good cell permeability and bio-compatibility.
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