APPLIED SURFACE SCIENCE
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2020
·
IF 6.182
Yiming Zhang,Xiaoyan Yang,Yonglin Wang,Peng Zhang,Dan Liu,Yongwei Li,Zhouzheng Jin,Bhekie B. Mamba,Alex T. Kuvarega,Jianzhou Gui
For obtaining ultra-fine Cu 2 S nanoparticles with reduced recombination of their photogenerated electron/hole pairs, in-situ growth of Cu 2 S nanoparticles on exfoliated MoS 2 nanosheets was achieved in this study. We have exhaustively studied l -cysteine in-situ conjugation with sulfur defects on the surface of MoS 2 nanosheets, which makes particle-level superlattice structured Cu 2 S nanoparticles (average 6.2 nm) well disperse on MoS 2 nanosheets. Further, XPS and Raman analysis confirm that the intense interfacial effects are formed between Cu 2 S and MoS 2 for the 2-Cu 2 S-MoS 2 composite, which significantly promote separation of photogenerated electron-hole pairs and prolong their lifetime, as shown by PL and TRPL. As a result, 2-Cu 2 S-MoS 2 exhibits the fastest photoreduction rate of Cr(VI) (0.0058 min −1 ) under visible light irradiations, which are almost 8.3 times and 2.9 times higher than that of MoS 2 nanosheets (0.0007 min −1 ) and pure Cu 2 S (0.002 min −1 ), respectively. Meanwhile, 2-Cu 2 S-MoS 2 also possesses an optimal composite proportion between Cu 2 S and MoS 2 , which presents outstanding photocatalytic activity among series of x-Cu 2 S-MoS 2 composites. The photoreduction mechanism of Cr(VI) is investigated in detail. As a matter of fact, l -cysteinecoupled with sulfur defects on MoS 2 nanosheets could produce the coordination inner heterojunction interface of 2-Cu 2 S-MoS 2 samples, which greatly improves migration efficiency of photoinduced carriers and ultimately endows it outstanding photoreduction activities. Furthermore, the strategy was extended to fabricate CdS-MoS 2 and ZnS-MoS 2 heterojunctions, implying that this strategy is of promising potentials for designing more active metal sulfides heterojunction photocatalysts.
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高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2020
·
IF 3.573
Congshu Feng,Yun Chen,Jun Shao,Haoqing Hou
Blending of poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) would produce polylactide stereocomplex crystallites (PLA SC). In the PLLA/PDLA specimens prepared by solution mixing or melt blending, the isomeric polymers were mixed in the molecular level. When the distance of these isomers increased, the crystallization behaviors of PLLA/PDLA were not clear yet. In this study, PLLA/PDLA blends were prepared by different electrospinning methods, i.e., spinning by mixed solution (DL-A), side-by-side mode (DL-B), and double spinnerets (DL-C). Results revealed that the distances between isomeric molecules increased in the order of DL-A, DL-B, and DL-C, and this distance influences the phase transition and subsequently crystallization behaviors. In the DL-A, the homochiral crystallites (HC) developed at first, and then SC formed in the specimen with lower content of PDLA. The formation of SC was observed at first, and less or no content of HC was developed with higher content of PDLA. For the DL-B group, the formation of HC was observed at ∼100 °C, and the SC were produced around 140 °C irrespective of composition. More content of SC was produced during or after melting of HC. When referring to the DL-C group, the HC developed at the first stage, and the SC were produced during or after melting of PLA HC. In addition, the SC that developed in the three groups have different nucleation efficiencies for the subsequent formation of HC. The nucleation efficiency increased in the order of DL-A < DL-B < DL-C, and these results hinted that not only the content but also the distribution of SC affects the formation of HC.
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POLYMER
·
2020
·
IF 4.231
Dianliang Zhang,Desheng Qi,Jiayu Wang,Shuangjiang Yu,Chaoliang He,Mingxiao Deng
Injectable hydrogels have attracted great research interest for the delivery drugs and recruitment of cells to promote tissue regeneration. In this work, a series of the amino acid based methoxy-poly (ethylene glycol)- b -(poly ( γ -ethyl- l -glutamate- co / b - l -phenylalanine) block copolymers (mPEG- b -P (ELG- co / b -Phe)s) with similar block chain length, but different proportion and sequence of γ -ethyl- l -glutamate (ELG) and l -phenylalanine (Phe) arrangements were prepared through ring-opening polymerization method. The influence of the ratio and sequence structures of mPEG- b -P (ELG- co / b -Phe)s on their thermosensitive aqueous gelation behaviors were investigated in detail. The results showed that the obtained polymers showned higher modulus (G’) and lower critical gelation temperature with higher proportion of l -phenylalanine. However, the physical properties start to deteriorate as the copolymers have a large number of phenylalanine groups. To clarify this phenomenon, the analysis of secondary structure with circular dichroism (CD) and fourier transform infrared (FTIR) spectrum showed that random coil reached a higher percentage as incorporated phenylalanine groups increased. On the other hand, the polymers with different sequence and similar compositions exhibited divergence due to the influence of random coil conformation. In addition, the good biocompatibility of mPEG- b -P (ELG- co -Phe)s were observed in vitro and in vivo . The copolymers have the potential to be used as thermo-sensitive injectable hydrogels for biomedical applications.
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JOURNAL OF FOOD PROCESSING AND PRESERVATION
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2020
·Vol. 44
·期 9
·e14691
·
IF 1.405
Liyang Wei,Changhong Liu,Jinjin Wang,Shoaib Younas,Huanhuan Zheng,Lei Zheng
In the current study, fresh-cut broccoli was soaked in melatonin solution before cold storage (4°C, 95% RH) for 25 days. The results indicated that 100 µM melatonin treatment inhibited the increase of L * and b * values and retained higher hue angle, total chlorophyll content, and fresh weight during storage. Furthermore, 100 µM melatonin treatment obviously increased antioxidant contents including ascorbic acid, total phenols, and flavonoids, and enhanced the antioxidant activity of florets. Individual phenolic compounds including epicatechin, rutin, and quercetin were positively influenced by melatonin treatment. Superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) activities were obviously enhanced by 100 µM melatonin treatment whereas peroxidase (POD) activity was significantly reduced. Moreover, florets treated with melatonin exhibited lower malondialdehyde (MDA), H 2 O 2 , and O 2 − levels. Our research concluded that melatonin treatment could be an effective technique for enhancing antioxidant capacity and improving the quality of fresh-cut broccoli during cold storage. Practical applications Fresh-cut fruits and vegetables are more prone to senescence than their intact forms during postharvest storage. Broccoli is a healthy vegetable and has high demands in many countries. In order to reduce economic losses, it is important to delay the senescence and maintain the quality of fresh-cut broccoli during postharvest storage. In this article, 100 µM melatonin treatment was found to significantly enhance antioxidant capacity and delay the senescence of fresh-cut broccoli florets, which maintained the quality of broccoli during cold storage. We believe that melatonin treatment can be applied for the preservation of more fresh-cut fruits and vegetables.
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AAPS PHARMSCITECH
·
2020
·Vol. 21
·期 3
·1-10
·
IF 2.401
Li Xin,Lu Chao,Xia Wenquan,Quan Guilan,Huang Ying,Bai Xuequn,Yu Feiyuan,Xu Qian,Qin Wanbing,Liu Daojun,Pan Xin
Protein drugs were considered to be the first choice to treat many human diseases, but their clinical application was usually limited by their short half-life and lack of validated targeted therapy. Here, a series of folate-functionalized poly(ethylene glycol)- b -(poly(2-aminoethyl-L-glutamate)- g -poly(L-glutamic acid))s (FA-PEG- b -(PELG- g -PLGA)s) were designed as tumor-targeted carriers for cationic protein delivery. Compared with traditional copolymers consisting of PEG and linear charged hydrophilic blocks, FA-PEG- b -(PELG- g -PLGA) with brush-like polyelectrolyte segments were beneficial to improving their electrostatic interactions with loading protein molecules, thus increasing drug-loading stability and protecting encapsulated proteins from degradation. The designed polymer brushes could efficiently encapsulate cytochrome C (CytC), a cationic model protein, to form polyion complex (PIC) micelles with an average particle size of approximately 200 nm. An in vitro drug release study showed that the drug-loading stability of the formed PIC micelles was largely improved. The functionalization of the block copolymer carriers with a targeting folate group enhanced the tumor cell growth inhibition and total apoptotic rates induced by CytC. Our results shed light on the unique advantages of brush-like polymer carriers in delivering cationic proteins, and the poly(L-glutamic acid)-based linear-brush diblock copolymers could be applied as a versatile delivery platform for molecular targeting in cancer therapy.
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PubMed
高影响因子
ENZYME AND MICROBIAL TECHNOLOGY
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2020
·
IF 3.448
Cun-Duo Tang,Hong-Ling Shi,Yuan-Yuan Jia,Xiang Li,Lin-Feng Wang,Jian-He Xu,Lun-Guang Yao,Yun-Chao Kan
L -Phenylglycine ( L -PHG) is a member of unnatural amino acids, and becoming more and more important as intermediate for pharmaceuticals, food additives and agrochemicals. However, the existing synthetic methods for L -PHG mainly rely on toxic cyanide chemistry and multistep processes. To provide green, safe and high enantioselective alternatives, we envisaged cascade biocatalysis for the one-pot synthesis of L -PHG from racemic mandelic acid. A engineered E. coli strain was established to co-express mandelate racemase, D -mandelate dehydrogenase and L -leucine dehydrogenase and catalyze a 3-step reaction in one pot, enantioselectively transforming racemic mandelic acid to give L -PHG ( e.e. >99 %). After the conditions for biosynthesis of L -PHG optimized by response surface methodology, the yield and space-time yield of L -PHG can reach 87.89 % and 79.70 g·L −1 ·d −1 , which was obviously improved. The high-yielding and enantioselective synthetic methods use cheap and green reagents, and E. coli whole-cell catalysts, thus providing green and useful alternative methods for manufacturing L -PHG.
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COMPOSITES PART B-ENGINEERING
·
2021
·
IF 9.078
Ting Gu,De-xiang Sun,Xiao-dong Qi,Jing-hui Yang,Cheng-shou Zhao,Yan-zhou Lei,Yong Wang
The wide application of the biodegradable polymers is the developing direction of the next generation microelectronic devices and electronic packaging because it can greatly reduce the risk of plastic pollution. However, most of biodegradable polymers have low thermal conductivity and low heat resistance. Synchronously improving the thermal conductivity and heat resistance of the biodegradable polymers without sacrificing the other performances is still great challenging. In this work, a novel method was proposed to highly efficiently improve the thermal properties of the poly( l -lactic acid) (PLLA) composites. To achieve this goal, hydroxylated graphene nanoplatelets were obtained by wet ball milling technology, and then ring-opening polymerization of lactide was initiated, and poly( d -lactic acid) (PDLA) and PLLA molecular chains were grafted on the hydroxylated graphene nanoplatelets to obtain the PDLA-graft-graphene nanoplatelets (G-g-PDLA) and PLLA-graft-graphene nanoplatelets (G-g-PLLA), respectively. Finally, the PLLA/G-g-PDLA and PLLA/G-g-PLLA composites were fabricated through melt compounding processing. The results showed that the PDLA molecular chains on the graphene nanoplatelets promoted the formation of the stereocomplex crystallites at the interface. Compared with the pure PLLA and PLLA/G-g-PLLA composites, the PLLA/G-g-PDLA composites exhibited higher thermal conductivity, largely enhanced heat distortion temperature, and better mechanical properties at high environmental temperature. For example, at G-g-PDLA content of 5 wt %, the composite sample showed the thermal conductivity of 1.12 W m −1 K −1 and heat distortion temperature of 200 °C, which were 387 % and 65 °C higher than those of the pure PLLA, respectively. Morphological and microstructural characterizations were carried out and the mechanisms based on SCs formation at the interface were proposed. This work lights up the route for the application of the PLLA in the next generation microelectronic devices.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Shengnan Li,Jiwei Jiang,Shih-Hsin Ho,Fengxiang Li,Wenlu Zeng
Microbial fuel cells (MFCs) systems are up-and-coming technologies for renewable energy production and wastewater treatment simultaneously. However, the inactive oxygen reduction reaction (ORR) on the cathode markedly limits the functioning of MFCs. Therefore, the cathodic catalyst is one of the crucial components in MFCs, this paper presents the removal of the antibiotic sulfamethoxazole (SMX) from water using single-chamber MFCs with Fe-Co-C/N as electrocatalysis. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were conducted to illustrate the structure and elemental composition of Fe-Co-C/N. The results obtained by the rotating disk electrode (RDE) method showed an extraordinary electrocatalytic activity of Fe-Co-C/N towards ORR in O 2 -saturated 0.1 M KOH. Furthermore, the degradation of SMX by MFCs that applied modified electrodes was also studied. The results demonstrated that using Fe-Co-C/N as air–cathode catalysts exhibited the degradation efficiency of 61.64% towards 6 mg/L SMX with 48 h. In addition, cyclic voltammetry (CV) analysis showed that the peak current of the biofilm in the PBS solution (without adding SMX) was significantly higher than that of the solution with SMX addition at 6, 18, and 30 mg/L. Moreover, MFC performance was also evaluated by measuring electrochemical impedance spectroscopy (EIS), power generation, and polarization curves. Last but not least, the high-throughput sequencing-based metagenomic technique was used to explore the microbial community diversity, functional genes in MFCs, and fate of ARGs. SMX addition raised the abundances of sul1 and sul2 as resistance genes, which enhanced microbial resistance, the coping capability of SMX toxicity, and the adjustment of the damage from SMX. The obtained results suggest that Fe-Co-C/N is a feasible catalyst for MFC cathodes owing to its satisfactory performance in terms of SMX wastewater treatment and power production.
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JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
·
2019
·
IF 4.978
Ping Kou,Yu-Fei Kang,Li-Tao Wang,Li-Jun Niu,Ying Xiao,Na Guo,Qi Cui,Yan-Yan Li,Yu-Jie Fu
This study explored an integrated strategy for extraction and preparative separation of four anthocyanins from Ribes nigrum L. using DES-based microwave assisted extraction and flash chromatography. The extraction yield of anthocyanins reached 2.03 mg/g after optimization. An efficient preparative separation process of four main anthocyanins by macroporous resin and flash chromatography was established afterwards. The yields of D3G, D3R, C3G and C3R reached 0.32 mg/g, 0.47 mg/g, 0.18 mg/g and 0.43 mg/g with the purities of more than 95%, respectively. The developed procedure represents an efficient and convenient alternative for the systematic utilization of natural products from plant materials.
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高影响因子
MICROCHEMICAL JOURNAL
·
2020
·
IF 3.594
Ming-Zhu Gao,Qi Cui,Li-Tao Wang,Yao Meng,Lian Yu,Yan-Yan Li,Yu-Jie Fu
Green and tailor-made deep eutectic solvents (DESs) coupled with microwave-assisted extraction (MAE) were performed to extract phenolic compounds from mulberry leaves. Among the twelve DESs prepared, Choline chloride/Glycerol (1:2) with 20% water content was more efficient to get high extraction yields of phenolics. Then, several essential parameters of microwave-assisted deep eutectic solvents extraction (DES-MAE) were optimized by single-factor and Box-Behnken design (BBD) experiments. According to the result of optimization, the total extraction yield of target phenolic compounds reached 8.352 mg/g at microwave temperature 66 o C for extracting 18 min with the liquid/solid ratio of 20 mL/g, which was obviously superior to conventional solvent extraction. In addition, the extraction kinetic models confirmed that microwave-assisted extraction was a more efficient extraction technique than ultrasound-assisted extraction and heat-refluxing extraction. Meanwhile, the macroporous resin was utilized to enrich and separate target compounds from DES extracts, and the recovered DES still exhibited a good solvent effect to be applied for re-extraction. Therefore, DES-MAE followed by macroporous resin column chromatography was a green and integrated strategy for the extraction and preparative separation of active ingredients from plant materials.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2019
·Vol. 137
·期 18
·48646
·
IF 2.188
Meng Ma,Lin Xu,Kai Liu,Si Chen,Huiwen He,Yanqin Shi,Xu Wang
Reactive blending is an innovative method for the improvement of compatibility of polymer blend. In this work, poly ( L -lactic acid) and poly (butylene succinate) (PLLA/PBS) blends were prepared by melt blending to ameliorate the toughness of PLLA. Triphenyl phosphite (TPP) was introduced into the PLLA/PBS blends (80/20 by weight) to enhance their compatibility via reactive blending. The effects of TPP on the morphology and properties of PLLA/PBS blends were studied systematically. The increased torque during melt blending demonstrated that the compatibilizer successfully reacted with PLLA and PBS. The mechanical properties of the blends were exceedingly improved only with 0.5 wt% TPP. A reduction tendency of size of the dispersed phase was observed due to the improvement of compatibility. The DSC and DMA results indicate that the T g of PLLA decreased at a slow rate with the increasing content of TPP. This work provided a simple approach for preparing a kind of high toughed PLLA material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48646.
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Biotechnology Journal
·
2019
·Vol. 14
·期 7
·1800643
·
IF 3.543
Liwei Gao,Shiying Li,Yanning Xu,Chengqiang Xia,Jiadi Xu,Jun Liu,Yuqi Qin,Xin Song,Guodong Liu,Yinbo Qu
α- l -Arabinofuranosidases are important in the degradation of plant polysaccharides and are used in several industrial processes. Although the use of filamentous fungi for the production of α- l -arabinofuranosidases is widely reported, there are few reports on strain engineering for enhanced production of these enzymes by fungi. In this study, the function of transcription factor AraR in l -arabinose release and catabolism by the fungus Penicillium oxalicum ( P. oxalicum ) is investigated. Also, a mutant of AraR, AraR A731V , is constructed to improve the production of α- l -arabinofuranosidases on the basis of the sequence homology between AraR and the xylanolytic gene activator XlnR. The AraR A731V -overexpressing strain can synthesize α- l -arabinofuranosidase in the absence of an inducer and shows a 54.1-fold increase in α- l -arabinofuranosidase production and a 7.4-fold increase in α-galactosidase production in the medium containing wheat bran. Determination of the transcript abundances of lignocellulolytic enzyme genes reveals significant upregulation of multiple α- l -arabinofuranosidase genes and downregulation of some cellulolytic and xylanolytic enzyme genes in the engineered strain relative to its parent. Taken together, the results suggest the conserved regulatory function of AraR in the family Trichocomaceae and provide a strategy for engineering fungal strains for enhanced α- l -arabinofuranosidase production. Graphical α- l -Arabinofuranosidases are important in plant cell-wall degradation and are used in many industries. In this study, it is shown that a point mutation of transcription factor AraR could increase α- l -arabinofuranosidase production by 54.1-fold in the fungus Penicillium oxalicum .
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高影响因子
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