MACROMOLECULAR RESEARCH
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2021
·Vol. 29
·期 7
·462-469
·
IF 2.227
Wang Lei,Yan Shijing,Zhang Lei,Mai Yuliang,Li Weihao,Pang Hao
The degradation and recycling of waste epoxy resin products is an urgent environmental problem. To solve this issue, we use acid-/base-degradable 1,1′,1″-(1,3,5-hexahydro-s-triazine-1,3,5-triyl) tris(3-ethylamino-propan-1-one) (TAHT-EA) as curing agent to introduce the hexahydro-s-triazine (HT) ring structure into the cross-linking network to prepare degradable epoxy resin. Specifically, 1,3,5-triacryloylhexahydro-1,3,5-triazine (TAHT) and ethylamine quickly complete the Aza-Michael addition reaction at the interface of chloroform and water droplets under the catalysis of water. The FTIR spectra, NMR spectrum and mass spectrum show that mono- and bis-addition products of ethylamine coexist in the product in which the content of the primary addition product reaches 97%. TAHT-EA can be decomposed by acid and base solutions. Through NMR analysis of the degradation products, it can be explained that the degradation mechanisms are different. The breaking of amide bonds and HT rings in acid solution and the cracking of amide bonds in base solution are speculated to be the main mechanisms under these two different circumstances, respectively. We tested the mechanical, thermal and degradation properties of the epoxy resin cured by TAHT-EA, and compared it with the epoxy resin cured by 4,4′-diaminodiphenylmethane and triethylenetetramine. TAHT-EA-cured epoxy resin shows comparable mechanical properties with Young’s modulus up to 2.05 GPa and tensile strength up to 70.9 MPa. What is more, it degrades completely by 1 M H + /OH − solution at 60 °C within 36 h. Nevertheless, it exhibited a relatively low crosslinked density (633 mol/m 3 ) and low heat resistance (the initial decomposition temperature is lower than 205 °C). Overall, TAHT-EA cured epoxy resin has the potential to gradually replace traditional thermosetting resin, thereby solving the environmental problems caused by discarded epoxy resin products.
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NANO
·
2021
·
IF 1.556
Mengting Zhang,Xiaorong Li,Hong Xiao,Bin Zhao,Wei Bian
Graphene quantum dots (GQDs) have been extensively used in biosensors and bioimaging. Heteroatom-doped GQDs can regulate material properties and endow them to improve structural and physicochemical properties. In this work, N,S-GQDs were prepared through a high-temperature pyrolysis method using L-cysteine and citric acid as the precursors. The morphology and structure of nanocomposites were identified by TEM, X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), and FTIR. The as-prepared N,S-GQDs show bright blue fluorescence with satisfactory fluorescence quantum yield. N,S-GQDs display significant response to riboflavin, achieving a low detection limit of 27 nM. The reaction of N,S-GQDs to riboflavin is mainly governed by static quenching. The detection of riboflavin in real samples has been performed to demonstrate its practical application. The obtained N,S-GQDs have low cytotoxicity and have been applied successfully in cell imaging.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2021
·
IF 19.503
Shuaiqi Gong,Xue Teng,Yanli Niu,Xuan Liu,Mingze Xu,Chen Xu,Lvlv Ji,Zuofeng Chen
Zero-dimensional quantum dots (QDs) and two-dimensional nanosheets represent two kinds of distinctive materials with unique properties. Here, we describe the fabrication of step-scheme ( i.e. S-scheme) 0D/2D heterostructure with InVO 4 QDs and g -C 3 N 4 (CN) ultrathin nanosheets for photocatalytic CO 2 reduction. The formation of S-scheme heterostructure facilitates the separation of electron-hole pairs and reduces the recombination of charge carriers. Moreover, the light-absorption edge of InVO 4 /CN is extended to 605 nm because of the strong visible light absorption of InVO 4 QDs. The 0D/2D hybrid enables highly selective photocatalytic reduction of CO 2 to CO (93.3 %) at a decent rate of 69.8 μmol g −1 h −1 under visible light irradiation. Density functional theory (DFT) results suggest that the formation of InVO 4 /CN heterostructure can enhance CO 2 adsorption/activation, stabilize COOH* intermediates and allow rapid CO desorption as the major product. This study opens up a new possibility for construction of novel S-scheme heterostructure for photocatalytic applications.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Qiu Lv,Huilian Hao,Manman Ge,Wenyao Li
Sulfur doping is one of the most promising approaches to generate electron-dense active region on the surface of graphene-based materials. This work developed an environmental friendly method for synthesizing sulfur-doped graphene (SG)/mixed-valent manganese oxides (MnO x ). Three-dimensional (3D) SG is prepared by thermal treatment, and the uniformly doped sulfur provided more anchor points for the compound of subsequent mixed-valent manganese oxides . The final product SG-MnO x (x stands for mixed valence) composite was obtained by one-pot hydrothermal method in which mixed-valence manganese oxides were synthetized and compounded the SG simultaneously. The specific capacitance of SG-MnO x electrode at 0.5 A g −1 is 1311 F g −1 and the long-life cycle retention after 5000 cycles is 81.2%. The excellent manifestation of supercapacitors primarily attributed to the sulfur doping and synergistic effect with MnO x compound. This allows the SG-MnO x electrode to exhibit much better electrochemical performance than the two individual materials. The asymmetric supercapacitor with SG-MnO x and AC exhibits an excellent energy density (21.23 Wh kg −1 ) with power density of 1.5 kW kg −1 . The above performance indicates that SG-MnO x is one of the materials for supercapacitors with great promise.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2019
·
IF 5.589
Xiaobin Liao,Xingji Bai,Huan Qi,Fei Li,Baoling Yuan
N-nitrosodimethylamine (NDMA) has recently been discovered to generate from daminozide (DMNZD) during ozonation . Moreover, its formation is affected by the presence of bromine ion (Br − ) in water, but the mechanism is still unclear. In this study, the effect of Br − on NDMA formation from DMNZD during ozonation at various oxidation conditions (ozone dosages, pH) and distinct water parameters was studied. In addition, the transformation pathways with/without Br − were determined. The results demonstrated that low levels of Br − promoted NDMA formation from DMNZD during ozonation. When Br − dosages increased from 0 to 1 μM, the concentration of NDMA augmented from 138 to 195.5 μg/L. However, when Br − concentration raised to 100 μM, NDMA amounts dropped to 80 μg/L. Increasing pH can raise the ratio of deprotonated DMNZD no matter with or without Br − , and promote its reaction with O 3 molecular to achieve the maximum NDMA formation at pH = 7. The amounts of NDMA decreased dramatically (from 155 to 74 μg/L) when HCO 3 – dosages increased from 0 to 160 μM with 0.1 μM Br − , however, its concentration increased remarkably (from 155 to 225 μg/L) with increasing SO 4 2− (from 0 to 20 μM). Low levels of HA (0.1–0.2 mg/L) boosted NDMA formation while relatively abundant of HA (≥0.4 mg/L) suppressed its formation. In addition, the presence of NOM inhibited NDMA formation from DMNZD during ozonation no matter Br − existed or not. Based on the results of LC/MS/MS, GC/MS and IC-MS, the transformation pathways of DMNZD with/without Br − during ozonation were proposed. This study provided new insights into the role of Br − on NDMA formation from typical amine compounds during ozonation.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2019
·
IF 4.084
Ao Nan Lai,Peng Cheng Hu,Jing Wei Zheng,Shu Feng Zhou,Lei Zhang
A series of novel fluorene-containing poly(arylene ether sulfone nitrile)s (FPESN-m/n) multiblock copolymers bearing 1,2-dimethylimidazole groups (ImFPESN-m/n) were synthesized for preparing anion exchange membranes (AEMs). Bromination rather than chloromethylation was used in this work. The bulky and rigid fluorene groups were introduced to force each chain apart to create large interchain spacing. Strong polar nitrile groups were introduced into the hydrophobic segments with the intention of enhancing the anti-swelling property of the AEMs. The length of fluorene–containing hydrophobic segment was varied to study the structure–property of the AEMs. With the ion groups anchored selectively and densely on the hydrophilic segments, all the AEMs exhibited well-defined hydrophilic/hydrophobic microphase-separated structures. As a result, the AEMs showed high hydroxide conductivities in the range of 35.2–118.3 mS cm −1 from 30 to 80 °C and superb ratios of ionic conductivity to swelling at 80 °C. Furthermore, the AEMs also exhibited good mechanical properties , thermal and alkaline stabilities.
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ANALYTICAL CHEMISTRY
·
2019
·
IF 6.35
Yameng Han,Tianyu Chen,Yiliang Li,Langxing Chen,Lin Wei,Lehui Xiao
Glutathione S-transferase (GST) is a group of multifunctional enzyme and participates in many physiological processes, such as xenobiotic biotransformation, drug metabolism, and degradation of toxic products. Herein, we demonstrate a label-free fluorescent conjugated polymer nanoparticle (FCPNPs)-based single-particle enumeration (SPE) method for the sensitive GST assay. Fluorescence resonance energy transfer (FRET) is formed between the glutathione-modified FCPNPs (FCPNPs-GSH) and polyethylenimine-capped gold nanoparticles (GNPs@PEI). Therefore, the fluorescence of FCPNPs-GSH is quenched remarkably. In the presence of GST, GNPs@PEI stay away from FCPNPs-GSH due to the specific interaction between FCPNPs-GSH and GST, leading to the inhibition of FRET. As a result, the fluorescence emission of FCPNPs-GSH is restored, which is reflected as the increase of the number of fluorescent particles in the microscopic image. By statistically counting the target concentration-dependent fluorescent particle number, accurate quantification of GST is achieved. The linear range from 0.01 to 6 μg/mL is obtained for GST assay and the limit-of-detection (LOD) is 1.03 ng/mL, which is much lower than the ensemble fluorescence spectra measurements in bulk solution. In urine sample assay, satisfactory recoveries in the range of 97.5–106.5.0% are achieved. Because of the high sensitivity and excellent specificity, this method can be extended to the detection of other disease-related biomolecules in the future.
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PubMed
高影响因子
JOURNAL OF CATALYSIS
·
2019
·
IF 7.723
Shuo Geng,Weiwei Yang,Yong Sheng Yu
Developing the stable and efficient hydrogen evolution reaction (HER) electrocatalyst is greatly desirable for the production of hydrogen as a clean energy resource. Herein, we report a simple and effective approach to fabricate MoS 2 /S-doped g-C 3 N 4 layered heterojunction electrocatalysts, which can adjust the electron structure, enhance the charge transfer rate and expose more active sites of MoS 2 for HER. The optimized MoS 2 -C 3 N 4 -60 sample shows a small onset overpotential as low as 115 mV, a low overpotential of 173 mV to achieve current density of 10 mA/cm 2 , a low Tafel slope of 53 mV decade −1 , and a high turnover frequency of 0.16 H 2 s −1 per active site at η = 150 mV. This finding proposes a new strategy to fabricate 2D layered heterojunction for enhancing HER performance by rationally coupling two similar layered materials.
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JOURNAL OF FOOD BIOCHEMISTRY
·
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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PubMed
高影响因子
CHIRALITY
·
2019
·Vol. 32
·期 2
·231-238
·
IF 1.927
Peng Wu,Mengjie Zhang,Yinjun Zhang,Zhao Wang,Jianyong Zheng
In this study, a novel lipase M5 derived from Aspergillus oryzae WZ007 was prone to exhibit high hydrolytic activity and stereoselectivity towards racemic substrate ( R , S )-ethyl 2-bromoisovalerate. ( R )-ethyl 2-bromoisovalerate was obtained by enzymatic resolution, which is the key chiral intermediate for highly efficient enantiomerically fluvalinate. The results showed that the enzymatic reaction was carried out in 120mM racemic substrate for 3 hours, the enantiomeric excess reached 98.6%, the conversion was 51.7%, and E value above 120. Therefore, the novel lipase M5 has the ability to efficiently produce ( R )-ethyl 2-bromoisovalerate, which greatly reduces the industrial production cost of the highly efficient counterpart of fluvalinate.
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PubMed
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2019
·
IF 4.561
Xiyu Zang,Mingfeng Chang,Lan Zheng,Yingying Zhou,Yuqi Wang,Jiahao Ren,Le Wu,Xiaolong Han,Qian Wang,Jinqiao Wu
Three novel quaternary ammonium based poly(ionic liquid)s (PILs) were prepared and developed, expecting to increase the viscosity of liquid CO 2 (LCO 2 ). The Vinyl benzoate and various quaternary ammonium salts was used to provide CO 2 -philicity group and viscosity-increasing groups respectively. And the PILs products (TDBAS, HDBAS and SDBAS) were synthesized with three processes consisting of polymerization, sulfonation and ion exchange. The characterization results of gel permeation chromatography (GPC), nuclear magnetic resonance spectrum (NMR), fourier transform infrared spectrometer (FT-IR), element analysis (EA) and thermogravimetric analysis (TGA) confirmed the successful synthesis of the PILs. Based on the discussion of reverse micelle microstructures and interfacial tension of prepared PILs systems, the viscosity-increasing mechanisms of the prepared PILs were analyzed and explicated. The experimental results indicated that the HDBAS presented an outstanding viscosity-increasing effect and acceptable water solubility among all the PILs, which may have a prosperous prospect in the near future.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2019
·Vol. 136
·期 37
·47957
·
IF 2.188
Jingtao Dai,Zhijun Wu,Liuyang Tang,Jinqing Qu
Cyclic carbonates reacted with diamines or polyamines have been proposed as a greener and safer method to prepare free isocyanate polyurethane coatings. Here, five kinds of bis(cyclic carbonate)s (TDC: toluene bis(cyclic carbonate), MDC: 4,4′-diphenylmethane bis(cyclic carbonate), IPDC: isophorone bis(cyclic carbonate), HMDC: 4,4′-methylenebis(cyclohexyl cyclic carbonate), HDC: hexamethylene bis(cyclic carbonate)) were prepared by reacting glycerol carbonate with diisocyanate under atmospheric pressure. Their structures were verified by 1 H-NMR and 13 C-NMR. These difunctional cyclic carbonates were then reacted with several amines to prepare new polyhydroxyurethane (PHU) coatings, and the film properties were tested. It was found that PHUs based on aromatic and alicyclic structures including TDC, MDC, IPDC, and HMDC displayed high hardness but had poor flexibility and impact resistance, whereas PHUs based on aliphatic structures such as HDC exhibited good flexibility and impact resistance and low hardness. When the length of the alkyl groups in the amine curing agents increased, the impact resistance and flexibility of the PHUs increased, but their pencil hardness decreased. PHUs from TDC, MDC, and IPDC had excellent chemical resistance, but the PHUs from HMDC and HDC had less chemical resistance. Some films displayed excellent properties including 4H pencil hardness, 100 cm kg impact resistance, and excellent flexibility. Some PHUs exhibited good thermal stability, with T 5% values all above 242°C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47957.
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