ACS Sustainable Chemistry & Engineering
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2019
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IF 6.97
Mingjie Chen,Rui-Min Li,Troy Runge,Jin Feng,Jing Feng,Songnan Hu,Qing-Shan Shi
Cellulose acetate is one of the oldest synthetic thermoplastic polymers and has various applications including usage as films, fibers, and membrane products. Traditionally, cellulose acetate is prepared by reacting cellulose with acetic anhydride in acetic acid using sulfuric acid as a catalyst. This process suffers from extensive depolymerization of the cellulose molecules and corrosion of the equipment from the use of the acidic solvent and catalyst. Herein we present an acid-free cellulose acetylation process using vinyl acetate as both the reactant and reaction medium and 1-ethyl-3-methylimidazolium acetate as the catalyst. The obtained cellulose acetate was confirmed by FTIR, NMR, and XRD studies. Additionally, the reaction kinetics, mechanism of the process, and properties of the obtained cellulose acetate were studied. Cellulose triacetate was obtained by our process within 2 h at 90 °C. The reaction kinetics was described with the classical pseudo-first-order rate expression of heterogeneous cellulose acetylation. The reaction mechanism was shown to be a peel-off mechanism similar to that of cellulose acetylation by the traditional acetic acid process. The molecular weight of the cellulose acetate produced by this new process was significantly higher than that from the traditional acetic acid process because of the absence of strong acids, which can depolymerize cellulose. In summary, we describe a new acid-free process to produce cellulose acetate that limits cellulose depolymerization and avoids the use of corrosive chemicals.
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ANALYTICAL CHEMISTRY
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2019
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IF 6.35
Juan Li,Xu Zhao,Li-Jian Chen,Hai-Long Qian,Wen-Long Wang,Cheng Yang,Xiu-Ping Yan
Aflatoxin B1 (AFB1) contamination is one of the most critical global issues in food safety. The high carcinogenic nature necessitates rapid and specific methods for the determination of AFB1 in foodstuffs at ultratrace levels. Here, we report an enhanced bienzymatic chemiluminescence competitive immunoassay for ultrasensitive and high-throughput determination of AFB1. In this assay, protein G was first coated on the wells of a microplate for recognizing the Fc fragment of anti-AFB1 mAbs to reduce the antibody dosage and guarantee high immunological reaction efficiency. The target AFB1 competed with glucose oxidase labeled AFB1 for the limited anti-AFB1 mAbs in the wells of the microplate. p-Bromophenol was employed as an enhancer to obtain intense and long-lasting chemiluminescence. The utilization of an enhancer and bienzymatic catalysts effectively improved the detection sensitivity. The developed method offered a good linearity over 5 orders of magnitude, a detection limit of 5 pg L–1, and a relative standard deviation of 1.9% for AFB1. The application of the developed method to the analysis of grain samples gave quantitative recoveries from 94.0% to 97.0%. The developed method provides a universal platform for high-throughput, ultrasensitive, and high specific detection of pollutants or nutrients in foods.
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JOURNAL OF CHROMATOGRAPHY A
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2019
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IF 3.858
Shi-Yao Ma,Jun Wang,Li Fan,Hui-Ling Duan,Zhi-Qi Zhang
A fluorinated metal-organic framework material (F-MOF) was successfully prepared using tetrafluoroterephthalic acid (H 2 tfbdc) as the ligand and Zn(II) as the central metal ion. The F-MOF exhibited excellent adsorption performance for perfluorooctanoic acid (PFOA), with a maximum adsorption capacity of 419.8 mg g −1 . A sensitive dispersive solid-phase extraction using the F-MOF as an adsorbent, coupled with GC–MS analysis, was developed for detecting trace PFOA with a limit of detection as low as 2.6 ng L −1 . This method was applied to detect PFOA in environmental water samples, yielding satisfactory results.
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CARBOHYDRATE POLYMERS
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2019
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IF 6.044
Yue Su,Liang Li
The structural characterization and antioxidant activity of four Auricularia polysaccharides (A.cornea ACP)、A.auricula(AAP)、A.polytricha (APP) and M.fungus(MFP)) were studied in this paper. The results shown: polysaccharides of four Auricularia were mainly composed of mannose and galactose, all polysaccharides contained uronic acid and pyran ring structure with spectroscopy and NMR analysis. There was a significant difference in the total antioxidant capacity and APP was significantly higher than the other polysaccharides. The ability of APP to scavenge DPPH radicals and hydroxyl radicals was significantly higher than that of other polysaccharides, respectively. The molecular weight was significantly positively correlated with DPPH radicals, superoxide anion radicals and hydroxyl radicals. Total antioxidant capacity was significantly negatively correlated with fucose and galactose. The result indicated that fucose and galactose jointly determine total antioxidant capacity. The polysaccharide from four Auricularia had good oxidation resistance and could be used as natural antioxidants.
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Nanomaterials
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2019
·Vol. 9
·期 12
·1772
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IF 4.034
Kaisheng Yao,Nan Wang,Zhiyong Li,Weiwei Lu,Jianji Wang
Porous gold with well-defined shape and size have aroused extensive research enthusiasm due to their prominent properties in various applications. However, it is still a great challenge to explore a simple, green, and low-cost route to fabricate porous gold with a “clean” surface. In this work, porous worm-like Au has been easily synthesized in a one-step procedure from aqueous solution at room temperature under the action of ionic liquid tetrapropylammonium glycine ([N3333][Gly]). It is shown that the as-prepared porous worm-like Au has the length from 0.3 to 0.6 μm and the width of approximately 100–150 nm, and it is composed of lots of small nanoparticles about 6–12 nm in diameter. With rhodamine 6G (R6G) as a probe molecule, porous worm-like Au displays remarkable surface enhanced Raman scattering (SERS) sensitivity (detection limit is lower than 10−13M), and extremely high reproducibility (average relative standard deviations is less than 2%). At the same time, owing to significantly high specific surface area, various pore sizes and plenty of crystal defects, porous worm-like Au also exhibits excellent catalytic performance in the reduction of nitroaromatics, such asp-nitrophenol andp-nitroaniline, which can be completely converted within only 100 s and 150 s, respectively. It is expected that the as-prepared porous worm-like Au with porous and self-supported structures will also present the encouraging advances in electrocatalysis, sensing, and many others.Keywords:ionic liquids;porous worm-like Au;SERS enhancement;nitroaromatic reduction
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Polymers
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2019
·Vol. 11
·期 12
·2048
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IF 3.164
Qinrui Zhu,Dagang Li
Interface optimization in preparing natural fiber based biocomposite becomes a key factor that determines overall properties, especially mechanical performance. The solution for upgrading interfacial adhesion stemmed from polar fiber and nonpolar polymer remains unclear. Here, a kind of pulp fiber/acrylonitrile-butadiene-styrene (ABS) composite with content ratio of 1:1 was fabricated by functionalizing the cellulose fiber to coordinate interaction between fiber and ABS. With addition of 5 wt % polyacrylamide (PAM) there existed an interlinked three-element structure in composite. Three types of treatment to cellulose fiber, including alkali immersion, pivaloyl chloride grafting for 10 h and 20 h were conducted. Pulp fiber that was treated with alkali for one hour, followed by pivaloyl chloride reaction for ten hours, proved to be effective for interfacial adhesion. X-ray Photoelectron Spectroscopy (XPS) analysis reveals 21.9% of carbonyl and 12.1% of ester function in this fiber, which corresponds to oxidation and grafting. For its composite SEM picture displays that most of cellulose fiber are rooted in ABS and evident traces of tearing or fracture can be observed after tension test. DMA test indicates that this modified pulp fiber/ABS composite exhibits great compatibility, because of combined loss modulus peak ranging from 80 °C to 100 °C. Moreover, the well miscible composite has a tensile strength of 58.1 MPa and elastic modulus of 2515 MPa, increasing by nearly 50% and 60% from those of pure ABS, respectively.Keywords:ABS;modification;interfacial adhesion;compatibility;interlinked structure
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Polymer Chemistry
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2019
·Vol. 11
·期 4
·810-819
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IF 4.76
Akram Yasin,Yurong Chen,Yanxia Liu,Letao Zhang,Xingjie Zan,Yagang Zhang
Different from traditional polyethylenimine (PEI) modified Hg(II) adsorbent materials, a novel hyperbranched polythioamide adsorbent (SPD) was prepared by using sulfur, PEI and 1,4-diethynylbenzene (DEB) as monomers. There are tens and thousands of tons of sulfur produced from oil refinery processes as a major by-product each year, and its utilization becomes a concern due to its limited consumption, environmental problems and safety. Herein, a SPD was fabricated through a one-pot, catalyst-free polymerization which even can be solvent-free via using sulfur to solidify the liquid PEI. A kinetic study showed that the adsorption of Hg(II) ions followed the pseudo-second-order model, indicating chemical adsorption between Hg(II) ions and SPD. The SPD had a maximum adsorption capacity of 1161.99 mg g−1. FT-IR and XPS measurements indicated that the removal of Hg(II) by SPD was mainly controlled by the coordination interaction between Hg(II) ions and nitrogen groups (i.e., amine and imine groups), and also CS bonds of SPD. By using elemental sulfur, PEI becomes the backbone of the polymer system by forming –C(S)NH– and –C(S)N< groups unlike the grafted part of traditional PEI modified materials. TG, DTG, and DSC measurements showed that the main degradations occurred at around 160 °C and 360 °C.
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ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
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2019
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IF 4.527
You Zhou,De-Qiang Qin,Pei-Wen Zhang,Ben-Ju Liu,Xiao-Tian Chen,Zhi-Xiang Zhang
Azadirachtin , as the most promising and effective botanical insecticide, exhibits significant growth inhibition activity against agricultural and forestry pests. However, its biochemical effects at the metabolic level compared with those of other insect growth regulators have not been studied. Therefore, in this study, a GC–MS based untargeted metabolomics approach was applied to compare azadirachtin with pyriproxyfen (a juvenile hormone analog) and tebufenozide (a molting hormone analog) in terms of their metabolic effects on Bactrocera dorsalis larvae. The bioactivity of azadirachtin against B. dorsalis larvae was significantly different than those of pyriproxyfen and tebufenozide. A total of 693 mass features were recognized, and 112 metabolites were identified in this study. The results showed that a total of 16, 13 and 10 differentially regulated metabolites corresponding to 12, 5 and 8 pathways occur in Aza versus CK, Pyr versus CK and Teb versus CK group, respectively. Further analysis showed that 6 differentially regulated metabolites corresponding to 5 key pathways could be the primary differential metabolic response of B. dorsalis larvae to the three insect growth regulators. The pathways were myo-inositol corresponding to ascorbate and aldarate metabolism as the specific response of B. dorsalis larvae to azadirachtin; xylitol, xylulose and 3-aminopropionitrile corresponding to pentose and glucuronate interconversions, and cyanoamino acid metabolism as the common responses to azadirachtin and pyriproxyfen; and 3-hydroxypropionic acid and beta-alanine corresponding to propanoate metabolism and beta-alanine metabolism as the specific responses to tebufenozide. The results showed that the metabolic response of B. dorsalis larvae to azadirachitin is closer to that of pyriproxyfen than tebufenozide. The differentially regulated metabolites and pathways responsible for this difference are discussed.
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Agriculture-Basel
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2019
·Vol. 9
·期 12
·250
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IF 0
Hua Huang,Yueming Jiang
This study comprehensively analysed the chemical composition of the cuticle in pitaya fruits. The total coverage amount of the waxes versus cutin monomers accumulated at a ratio of 0.6, corresponding to masses per unit of 30.3 μg·cm−2and 50.8 μg·cm−2, respectively. The predominant wax mixtures weren-alkanes in homologous series of C20–C35, dominated by C31and C33; as well as triterpenoids with an abundant amount of uvaol, lupenon, β-amyrinon, and β-amyrin. The most prominent cutin compounds were C16- and C18-type monomers, in which 9(10),16-diOH-hexadecanoic acid and 9,10-epoxy-ω-OH-octadecanoic acid predominated, respectively. The average chain length (ACL) of aliphates in pitaya fruit cuticle (30.5) was similar to that estimated in leaf waxes, and higher than that in most of the fruit and petal waxes that have been reported. We propose that the relatively high ACL and wax/cutin ratio might enhance the cuticular barrier properties in pitaya fruit cuticle to withstand drought.Keywords:pitaya fruit;cuticle;wax;cutin;ACL
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Journal of Physical Chemistry C
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2019
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IF 4.309
Qinghua Deng,Yun Xu,Ziqun Wang,Tifang Miao,Xianliang Fu,Liancai Xu
The development of new catalysts based on nonprecious metals for photocatalytic H2 evolution reaction (HER) is a very challenging endeavor. In this work, we used density functional theory (DFT) to design a high performance photocatalyst based on CoIII(dmgH)2pyCl. The sample was then prepared and used for photocatalytic HER under visible light irradiation with Eosin-Y (EY2–) and triethanolamine (TEOA) as a photosensitizer and electron donor, respectively. The feasibility and rationality of the DFT design were verified by the consistency between the photocatalytic performances and the theoretical results. The developed catalyst even showed the capability of splitting of water for H2 evolution. As for the most promising CoIII(dmgH)2(pyrazine)Cl, 1356 μmol of H2 can be produced over 25 mg of catalyst after irradiation for 3 h. The deactivation and the mechanism for the evolution of H2 over the sample were further investigated. We believe that this study provides an effective strategy for the design of highly efficient photocatalysts for HER.
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INDUSTRIAL CROPS AND PRODUCTS
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2019
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IF 4.191
Xianghe Meng,Dan Xiao,Qin Ye,Xiaohua Nie,Jiasheng Wu,Lili Song
In recent years, in concern for human health, increasing attention was focused on sciadonic acid (SA), a unique Δ5-olefinic acid. Torreya grandis ( T. grandis ), a large, evergreen coniferous tree, whose seed yields rare and is known for a high level of SA. Triacylglycerols (TAGs) from the seeds of four different T. grandis varieties (Yuanfei, Xifei, Xiangyafei, and Zhimafei), were analyzed with respect to fatty acid profiles and positional distributions. The results indicated that SA represented the majority of the Δ5-olefinic acids in T. grandis seed oil. Irrespective of the variety, SA was naturally abundant at the sn-3 position of TAGs where they accounted for approximately 7.52%–12.00%. Based on this specific characteristic of Δ5-olefinic acids, T. grandis seed oil was subjected to a two-step enrichment process involving specific lipase-catalyzed ethanolysis and urea complexing. The content of SA in the fatty acid ethyl ester was increased to 80.14% from an initial value of 9.95%. These results suggested that the developed enrichment strategy was simple and effective in concentrating SA, and had the potential for commercial application.
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Journal of Chemistry
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2019
·
IF 1.727
Yuchao Feng,TianXin Fu,Liyuan Zhang,Changyuan Wang,Dongjie Zhang
The analytical method for the metabolomics of the 60 rice seeds from two main rice origins in Heilongjiang Province was developed based on gas chromatography coupled with mass spectrum. The specific differential metabolites between two rice origins were identified, and the distinguish of the two main origins was illustrated by using the R software platform with XCMS software package for gas chromatography coupled with mass spectrum data processing, combined with multivariate statistical analysis software. The result indicated that the 173 peaks were detected, and 54 of which were structurally identified, covering amino acids, aliphatic acid, sugar, polyols, and so on. By comparing the data of Wuchang and Jiansanjiang origins, it was found that there were 9 special metabolites in Wuchang origin and 8 special metabolites in Jiansanjiang origin. The 10 differential metabolites with significant changes (, VIP ≥ 1) were filtrated. It is indicated that the differential metabolites of rice carry information of their origin and there are the differences in the metabolites of rice in two main origins. The proposed method is expected to be useful for the metabolomic researches of rice.
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