ChemSusChem
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2020
·Vol. 13
·期 14
·3662-3670
·
IF 7.962
Hefeng Yuan,Shiwei Wei,Bin Tang,Zizai Ma,Jinping Li,Manab Kundu,Xiaoguang Wang
Graphical Flakes make O 2 : Self-supported ultrathin CoNiB nanoflakes are prepared by a simple one-step solid-state boronation. The unique sheet-like structure, bimetallic boride components, and optimal hybrid crystalline nature enable a synergistic promotion for the catalysis of the oxygen evolution reaction with long-term stability. The development of highly active and efficient nonprecious-metal electrocatalysts for the oxygen evolution reaction is important for the design of renewable energy production and storage devices. In this work, highly dense, ultrathin Co–Ni boride nanoflakes supported on a 3 D CoNi skeleton are fabricated in situ by a simple one-step, high-temperature, solid-state boronation process. As a result of the induced high electroactive surface area and low charge transfer resistance, CoNiB-700 exhibits high catalytic activity at an overpotential of 262 ( η 10 ) and 284 mV ( η 20 ) to deliver current densities of 10 and 20 mA cm −2 , respectively, with a Tafel slope of 58 mV dec −1 in an alkaline medium towards the oxygen evolution reaction. DFT calculations show that the Ni-regulated Co–B compound has a lower rate-determining energy barrier for the *OOH intermediate than the mono-Co–B compound, which facilitates the production of more active catalytic sites for an accelerated surface charge-transfer process for the oxygen evolution reaction.
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Acta Biomaterialia
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2021
·
IF 8.947
Ri-Tong Lan,Yue Ren,Xin Wei,Li-Zhi Tang,Nouman Ali Shah,Lu Xu,Shi-Shu Huang,Rizwan M. Gul,Jia-Zhuang Xu,Zhong-Ming Li
Oxidative stability of radiation crosslinked ultrahigh molecular weight polyethylene (UHMWPE) artificial joints is significantly improved by vitamin E (VE), but there is a dilemma that VE hinders crosslinking and thus jeopardizes the wear of UHMWPE. In this effort, we proposed an efficient strategy to stabilize UHMWPE under limited antioxidant contents, where VE and D-sorbitol (DS) were used as the primary antioxidant and the secondary antioxidant respectively. For non-irradiated blends with fixed antioxidant contents, oxidative stability accessed by oxidation induction time (OIT) of VE/DS/UHMWPE blends was superior to that of VE/UHMWPE blends, while DS/UHMWPE blends showed no increase in OIT. The cooperation between DS and VE exhibited a synergistic effect on enhancing the oxidative stability of UHMWPE. Interestingly, the irradiated VE/DS/UHMWPE blends showed comparable OIT but a significantly higher crosslink density than the irradiated VE/UHMWPE blends. The crystallinity, melting point, and in vitro biocompatibility of the blends were not affected by VE and DS. The quantitative relationships of mechanical properties , oxidation stability, crystallinity and crosslink density were established to unveil the correlation of these key factors. The overall properties of VE/UHMWPE and VE/DS/UHMWPE blends were compared to elucidate the superiority of the antioxidant compounding strategy. These findings provide a paradigm to break the trade-off between oxidative stability, crosslink density and mechanical properties, which is constructive to develop UHMWPE bearings with upgraded performance for total joint replacements. Statement of significance VE-stabilized UHMWPE is the most commonly used material in total joint replacements at present. However, oxidation and wear resistance of VE/UHMWPE implants cannot be unified since VE reduces the efficiency of radiation crosslinking. It limits the use of VE. Herein, we proposed a compounding stabilization by the synergy between VE and DS. The antioxidation capability of VE was revived by DS, thus enhancing the oxidation stability of unirradiated UHMWPE. The irradiated VE/DS/UHMWPE exhibited similar oxidation stability but higher crosslink density than irradiated VE/UHMWPE, which is beneficial to combat wear of UHMWPE and to inhibit the occurrence of osteolysis . This synergistic antioxidation strategy endows the UHMWPE joint material with good overall performance, which is of clinical significance.
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FOOD CHEMISTRY
·
2021
·
IF 7.514
Jing Li,Kunpeng Gao,Francesco Secundo,Xiangzhao Mao
Chitin, one of the most abundant renewable biopolymers on Earth, is commercially available from crustacean wastes. One critical step in converting chitin to high-value products is its degradation by chitinolytic enzymes to N -acetyl- d -glucosamine (GlcNAc), which plays a significant role in functional food and pharmaceutical industries. Here, we cloned and biochemically characterized two novel β - N -acetylglucosaminidases named SvNag2557 (family-84) and SvNag4755 (family-3) from Streptomyces violascens ATCC 27968. Both SvNag2557 and SvNag4755 exhibited strict substrate specificity toward N -acetyl chitooligosaccharides with GlcNAc as the sole product. Thus, a one-pot production for pure GlcNAc from chitin by an enzyme cocktail reaction was further developed. Under the co-action of an endo-type chitinase SaChiA4 and SvNag2557 (mass ratio 1:2), the final conversion rates of colloidal chitin and ionic liquid pretreated chitin to GlcNAc were 80.2% and 73.8% with GlcNAc purities of 99.7% and 96.8%, respectively.
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Advanced Composites and Hybrid Materials
·
2021
·Vol. 5
·期 3
·2193-2205
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IF 5.693
Huang Yajing,Chen Songlin,Ma Ruitong,Cheng Yalin,Jin Lun,Chen Guohua
A novel method has been developed to synthesize fine coal-based carbon composite particles containing rich nitrogen-doped microcrystalline structure with superior electromagnetic-shielding (EMI) performances using anthracite as raw material for the first time. Carbon composite was observed after reacting with furanmethylamine (FMA), followed by ball-milling and a high-temperature (1000 °C) thermal anneal. Carbon structure was assessed before and after reacting FMA with X-ray diffraction (XRD), Raman, Fourier transform infrared spectroscopy (FT-IR), temperature-programmed oxidation (TPO), and X-ray photoelectron spectroscopy (XPS). All data are consistent with the occurrence of Diels–Alder (D-A) reaction, providing D-A reaction occurred between coal and FMA for the first time. Because the D-A reaction changes the three-dimensional structure of coal and weakens the cross-linking of the coal structure, ball-milling modified coal reduces the size of coal particles without deepening the disorder of coal, and heat treatment caused the reverse reaction of D-A reaction, which improved the structural integrity of the carbon networks. The final product called “Coal-FBT” shows a maximum attenuation of 62.2 dB, which qualifies as excellent electromagnetic shielding as 50wt% mixed with paraffin. Graphical abstract The modified coal (Coal-FBT) showed a max SE T of 62.2 dB, which is much higher than the pristine coal (8.81 dB).
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Biosensors-Basel
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2021
·Vol. 11
·期 10
·378
·
IF 5.519
Jinfeng Quan,Yihan Wang,Jialei Zhang,Kejing Huang,Xuemei Wang,Hui Jiang
Arch-cruciform DNA are self-assembled on AuNPs/VS2scaffold as a highly sensitive and selective electrochemical biosensor for michigan cancer foundation-7 (MCF-7) breast cancer cells. In the construction, arch DNA is formed using two single-strand DNA sequences embedded with the aptamer for MCF-7 cells. In the absence of MCF-7 cells, a cruciform DNA labeled with three terminal biotin is bound to the top of arch DNA, which further combines with streptavidin-labeled horseradish peroxidase (HRP) to catalyze the hydroquinone-H2O2reaction on the electrode surface. The presence of MCF-7 cells can release the cruciform DNA and reduce the amount of immobilized HRP, thus effectively inhibiting enzyme-mediated electrocatalysis. The electrochemical response of the sensor is negatively correlated with the concentration of MCF-7 cells, with a linear range of 10~1 × 105cells/mL, and a limit of detection as low as 5 cells/mL (S/N = 3). Through two-dimensional materials and enzyme-based dual signal amplification, this biosensor may pave new ways for the highly sensitive detection of tumor cells in real samples.Keywords:MCF-7 cells;electrochemistry;2-D materials;signal amplification;DNA assembly
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ACS Applied Materials & Interfaces
·
2021
·
IF 9.229
Li Lin,Liangen Shen,Junfeng Zhang,Yiyan Xu,Zheng Fang,Peter Müller-Buschbaum,Qi Zhong
Wearable solar radiation sensors based on ionic hydrogels are facilely prepared to simultaneously monitor the radiation dose for the production of vitamin D and the prevention of sunburn. Tetramethylethylenediamine (TEMED) is neutralized with acrylic acid (AA) to obtain tetramethylethylenediamine acrylate (TEMEDA), which is further polymerized with acrylamide by a free radical reaction. By simply adding MB or NR during the polymerization, the final obtained ionic hydrogels can indicate solar radiation. Due to the extent of discoloration, the discoloration speed of MB and NR is correlated to the radiation dose. This wearable sensor can indicate the solar radiation dose required by the human body to synthesize vitamin D through the discoloration of the ionized hydrogel of MB, whereas those with NR are able to illustrate the threshold of radiation dose that causes potential skin hurt. Therefore, the benefit and drawback of solar radiation can be well balanced by optimizing the exposure time to solar irradiation. In addition, polyurethane cross-linked with a thermoresponsive coating is used as band for this wearable sensor. Due to the hydrophilicity below its transition temperature, the cross-linked band possesses the easy cleaning capability of stains after the daily wear. Such type of wearable sensor can be broadly used for monitoring the solar radiation, especially in outdoor activities.
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INSTRUMENTATION SCIENCE & TECHNOLOGY
·
2020
·
IF 1.418
Li-Ye Niu,Qi Wang,Wan-Ming Zhao,Jian-Ying Jing
A D-type optical fiber surface plasmon resonance (SPR) sensor based on gold film and Au nanoshells is described. The sensor has a smaller full width at half maximum (FWHM) and a higher quality factor. The influence of the coupling effect between the Au nanoshells and gold film with different internal and external diameter ratios on the sensor was investigated by the finite element method. The simulation results show that the coupling effect between the SPR of the gold film and the localized surface plasmon resonance (LSPR) of the Au nanoshells effectively improved the electric field strength of the sensing region. The refractive index measurements show that the sensitivity of the D-type fiber/gold film/Au nanoshell (50/40 AuNS) SPR sensor is 3064 nm/RIU, which is 993 nm/RIU higher than for the D-type fiber/gold film SPR sensor. The D-type fiber/gold film/Au nanoshell (50/40 AuNS) SPR sensor also provides good linearity with a value of 99.4%. The sensor reported in this paper can be used for reference in the development of high performance biosensors.
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POLYMER BULLETIN
·
2020
·Vol. 78
·期 1
·147-163
·
IF 2.014
Shao Jun,Xu Lanli,Pu Shouzhi,Hou Haoqing
Blending of poly( l -lactide) and poly( d -lactide) (PLLA, PDLA) results in the formation of poly(lactide) stereocomplex crystallites (SC). For the preparation method, numerous reports employed solution mixing and stirring to receive a product with uniform performance. However, the effect of stirring time during solution mixing on the subsequent crystallization behavior did not clear yet, and which is important for solution crystallization, casting and spinning. In this paper, linear PLLA and PDLA with various molecular weights were synthesized. The PLLA and PDLA solutions were mixed together and stirred for different times before casting. Results revealed that the structures of PLA SC and homochiral crystallites (HC) did not vary with change in the stirring time. More amount of content of SC with uniform structure and less amount of content of HC were produced in the specimens stirred for longer time. When the specimens crystallized either from the melt or from the melt-quenching, less amount of content of crystallites (total crystallinity of SC and HC) was produced and the melting temperature of SC and HC depressed in the specimens that were stirred for longer time. With the increase in molecular weights, the effect of stirring time on the crystallization behaviors declined. This investigation provides a route to tailor the crystallization behavior of PLLA/PDLA specimens.
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BIORESOURCE TECHNOLOGY
·
2019
·
IF 6.669
Ganqiao Ran,Dan Tan,Jiping Zhao,Fan Fan,Qiang Zhang,Xingjuan Wu,Peiyao Fan,Xinlei Fang,Xiaoyun Lu
d -Allulose is a promising low-calorie sweetener especially for diabetes and obesity patients. The functionalized polyhydroxyalkanoate (PHA) nano-beads decorated with d -tagatose 3-epimerase (DTE) was produced in recombinant endotoxin-free ClearColi , whereby the expression, purification, and immobilization of the active DTE were efficiently combined into one step. The immobilized DTE exhibited remarkable enzyme activity of 649.3 U/g beads and extremely high stability at a harsh working condition (pH 7.0–8.0, 65 °C). When DTE-PHA beads were subjected to enzymatic synthesis of d -allulose, a maximum conversion rate of 33% can be achieved at pH 7.0 and 65 °C for 3 h, and DTE-PHA beads retained about 80% of its initial activity after 8 continuous cycles. Moreover, the d -allulose/ d -fructose binary mixture can be simply separated by a single cation exchange resin-equipped chromatography. Taken together, DTE-PHA beads are promising and robust nano-biocatalysts that will remarkably simplify the production procedures of d -allulose, contributing to its cost-effective production.
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COLLOIDS AND SURFACES B-BIOINTERFACES
·
2019
·
IF 3.973
Lifen Wang,Pengpeng Xue,Mengqi Tong,Rui Chen,Waigeng Yang,Deli ZhuGe,Jiandong Yuan,Qing Yao,Yingzheng Zhao,Helin Xu
Inflammatory bowel diseases (IBDs) are chronic relapsing disorders of the gastrointestinal tract characterized pathologically by intestinal inflammation and epithelial injury. Laquinimod (LAQ), a poorly water-soluble compound, was proved to be effective for colitis remission at low dose of 0.5 mg/kg in patients with Crohn’s disease. Due to its extremely low solubility in water, it was difficult to develop an injectable liquid dosage form. Herein, D-α-Tocopheryl polyethylene glycol-1000 succinate (TPGS) polymeric micelles were developed as a delivery vehicle of LAQ for the management of inflammatory bowel disease. Using the LAQ/TPGS ratio of 1:100, LAQ-loaded micelles were successfully prepared by thin-film dispersion method. The solubility of LAQ in water was significantly increased from 10.5 μg/mL in pure water to 500 μg/mL in TPGS micelles. LAQ-loaded micelles of TPGS exhibited the fine particle size of 34.6 nm and Zeta potential of -0.67 mV. Moreover, the good stability of LAQ-loaded micelles in physiology-mimicking medium was confirmed by detecting their particle size, zeta potential and leakage of the loading drug. Therapeutic effect of LAQ-loaded micelles on DSS-induced mice was proved by detecting DAI score, colon length and loss of body weight. Moreover, the morphology and colonic mucosal barrier of the injured colon of DSS-induced mice was largely recovered after treatment with LAQ-loaded micelles. Meanwhile, the inflammation of colitis colon was also obviously alleviated by LAQ-loaded micelles. Conclusively, polymeric micelles of TPGS may be a promising delivery vehicle of LAQ for the management of inflammatory bowel disease.
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Food Science & Nutrition
·
2019
·Vol. 7
·期 6
·2043-2049
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IF 1.747
Yujing Sun,Li Zeng,Yuanzhong Xue,Tianbao Yang,Zongming Cheng,Peilong Sun
β- d -glucosidase can release aroma precursors to improve the flavor of plant food, but the hydrolysis efficiency of the enzyme is low; the purpose of this study was to improve the enzyme activity using ultrasound. The effects of ultrasound parameters on β- d -glucosidase activity were investigated, and the respective structures of enzyme activated and enzyme inhibited were further analyzed. Low temperature (20–45°C), low ultrasonic intensity (<181.53 W/cm 2 ), and short treatment time (<15 min) led to the activation of β- d -glucosidase, whereas high temperature (45–60°C), high ultrasonic intensity (>181.53 W/cm 2 ), and long treatment time (>15 min) led to its inhibition. Application of ultrasound lowered the optimum temperature for β- d -glucosidase activity from 50 to 40°C. Ultrasound did not change the primary structures of the enzyme, but changed the secondary structures. When ultrasound activated β- d -glucosidase, the α-helix contents were increased, the β-fold and irregular coil content were reduced. When ultrasound inhibited β- d -glucosidase, the contents of β-folds were increased, the α-helix and irregular coil contents were reduced.. In summary, activation or inhibition of β- d -glucosidase under ultrasound was determined by the ultrasound conditions. This study suggests that ultrasound combined with β-D-glucosidase can be used in aroma-enhancing.
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APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2018
·Vol. 102
·期 14
·6039-6046
·
IF 3.34
Tigu Fitsum,Zhang Junli,Liu Guoxia,Cai Zhen,Li Yin
d -Pantothenic acid (vitamin B 5 ) has wide applications in the feed, food, chemical, and pharmaceutical industries. Its biological production routes which employ pantothenate synthetase (PS) as the key enzyme are attractive since they avoid the tedious and time-consuming optical resolution process. However, little data is available on the activity and kinetics of this enzyme, hampering the rational selection of an efficient enzyme for the biological production of d -pantothenic acid. In this study, six phylogenetically distant PS-encoding genes, from Escherichia coli , Corynebacterium glutamicum , Bacillus subtilis , Bacillus thuringiensis , Bacillus cereus , and Enterobacter cloacae , were expressed in E. coli . The PS from C. glutamicum exhibited a specific activity of 205.1 U/mg and a turnover number of 127.6 s -1 , which to our best knowledge are the highest values ever reported. The addition of substrates ( d -pantoic acid and β-alanine) to the E. coli strain harboring this enzyme during the early log phase of fermentation resulted in the production of 97.1 g/L of d -pantothenic acid within 32 h, corresponding to a conversion yield of 99.1% and a productivity of 3.0 g/L/h. To the best of our knowledge, this is the highest productivity reported to date.
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危险品化学品经营许可证（带存储）