ChemSusChem
·
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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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
·
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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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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Food Science & Nutrition
·
2019
·Vol. 7
·期 6
·2043-2049
·
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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NEUROTOXICOLOGY
·
2018
·
IF 3.076
Jing Zheng,Juan Chen,Xiaohan Zou,Fang Zhao,Mengqi Guo,Hongbo Wang,Tian Zhang,Chunlei Zhang,Wei Feng,Isaac N. Pessah,Zhengyu Cao
Saikosaponins (SSs) are a class of naturally occurring oleanane-type triterpenoid saponins found in Radix bupleuri that has been widely used in traditional Chinese medicine. As the main active principals of Radix bupleuri , SSs have been shown to suppress mouse motor activity, impair learning and memory, and decrease hippocampal neurogenesis. In the present study, we investigated the effect of five SSs (SSa, SSb1, SSb2, SSc, and SSd) on neuronal viability and the underlying mechanisms in cultured murine neocortical neurons. We demonstrate that SSa, SSb1 and SSd produce concentration-dependent apoptotic neuronal death and induce robust increase in intracellular Ca 2+ concentration ([Ca 2+ ] i ) at low micromolar concentrations with a rank order of SSd > SSa > SSb1, whereas SSb2 and SSc have no detectable effect on both neuronal survival and [Ca 2+ ] i . Mechanistically, SSd-induced elevation in [Ca 2+ ] i is the primary result of enhanced extracellular Ca 2+ influx, which likely triggers Ca 2+ -induced Ca 2+ release through ryanodine receptor activation, but not SERCA inhibition. SSd-induced Ca 2+ entry occurs through a non-selective mechanism since blockers of major neuronal Ca 2+ entry pathways, including L-type Ca 2+ channel, NMDA receptor, AMPA receptor, Na + -Ca 2+ exchanger, and TRPV1, all failed to attenuate the Ca 2+ response to SSd. Further studies demonstrate that SSd increases calcein efflux and induces an inward current in neocortical neurons. Together, these data demonstrate that SSd elevates [Ca 2+ ] i due to its ability to increase membrane permeability, likely by forming pores in the surface of membrane, which leads to massive Ca 2+ influx and apoptotic neuronal death in neocortical neurons.
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MATERIALS SCIENCE FORUM
·
2019
·
IF 0
Ji Fu Du,Zhen Dong,Xin Yang,Long Zhao
Glycidyl methacrylate (GMA) was grafted onto the surface of HDPE particles by radiation grafting and emulsion graft copolymerization. And subsequent ring-opening reaction of expoxy groups in poly-GMA graft chains with N-methylglucamine (NMG) was conducted to synthesis the boron adsorbent. The synthesis condition (radiation dose and NMG concentration) was optimized and characterized by IR and SEM. Adsorption behaviors of the boron adsorbent for boron removal presented that adsorption kinetics was well described by pseudo-second-order kinetic mode. The adsorption isothermal was well fitted with both Langmuir and Freundlich isotherm models. The adsorption capacity for boron reached 15.63 mg/g at optimal pH 8. Dynamic experiment revealed that boron could be efficiently adsorbed by the boron adsorbent and fully desorbed using 13 BV of 1 mol/L HCl.
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Journal of Functional Foods
·
2019
·
IF 3.197
Ze-hua Li,Ming Cai,Kai Yang,Pei-long Sun
Nanoemulsion loading finger citron essential oil (FCEO) can maintain bioactivities of FCEO and increase its water solubility. In this study, stability of FCEO nanoemulsions during digestion in vitro were evaluated and the release kinetics of d-limonene (the main component in the oil) were developed. Compared with free oil released to maximum for 6 min, all nanoemulsions kept sustainably releasing for 300 min or longer. Droplet size of the nanoemulsions increased from 10–18 nm of initial to 105–1106 nm after digestion, indicating coalescence or aggregation occurred. Zero-order, Hixcon-Crowell, Higuchi, Ritger-Peppas and Niebergull models were used to describe the release kinetics. The results showed zero-order and Ritger-Peppas models were the best fit models at mouth and intestinal stage, respectively. Both zero-order and Higuchi models were appropriate at gastric stage. This study could demonstrate the digestion mechanisms of FCEO loaded nanoemulsion and facilitate the design of hydrophobic nutraceuticals delivery systems in food industry.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2015
·
IF 4.097
Jianmei Wang,Huihui Zhu,Yuanhong Xu,Wenrong Yang,Ao Liu,Fukai Shan,Mengmei Cao,Jingquan Liu
Herein, a uniform three-dimensional (3-D) graphene nanodots-encaged porous gold electrode was prepared via ion beam sputtering deposition (IBSD) and mild corrosion chemistry for efficient enzyme electrode fabrication. Enzymes, like glucose oxidase and catalase , were modified with pyrene functionalities and then loaded into the graphene nanodots encaged porous gold electrode via non-covalent π–π stacking interaction between pyrene and graphene. The fabricated enzyme electrodes showed profound reusability and repeatability, high sensitivity, inherent selectivity and enhanced detection range. As for glucose analysis a broad linear range from 0.05 to 100 mM was obtained and the linear range for hydrogen peroxide was 0.005 to 4 mM. Detection limits of 30 μM for glucose and 1 μM for hydrogen peroxide were achieved ( S / N = 3), respectively. These electrodes can be applied to analyze the clinical samples with reliable results. The formation mechanism and 3-D structure of the porous electrode were investigated using high resolution transmission electron microscope (HRTEM), atomic force microscopy (AFM), scanning electron microscope (SEM) and electrochemical impedance spectroscopy (EIS). Most importantly, various other ideal biosensors can be fabricated using the same porous electrode and the same enzyme modification methodology.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2014
·
IF 2.129
Peng Wang,Bang Lin Li,Nian Bing Li,Hong Qun Luo
In this contribution, a luminescent gold nanoclusters which were synthesized by bovine serum albumin as novel fluorescent probes were successfully utilized for the determination of d -penicillamine for the first time. Cupric ion was employed to quench the strong fluorescence of the gold nanoclusters, whereas the addition of d -penicillamine caused obvious restoration of fluorescence intensity of the Cu 2+ -gold nanoclusters system. Under optimum conditions, the increment in fluorescence intensity of Cu 2+ -gold nanoclusters system caused by d -penicillamine was linearly proportional to the concentration of d -penicillamine in the range of 2.0 × 10 −5 –2.39 × 10 −4 M. The detection limit for d -penicillamine was 5.4 × 10 −6 M. With the off–on fluorescence signal at 650 nm approaching the near-infrared region, the present sensor for d -penicillamine detection had high sensitivity and low spectral interference. Furthermore, the novel gold nanoclusters-based fluorescent sensor has been applied to the determination of d -penicillamine in real biological samples with satisfactory results.
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危险品化学品经营许可证（带存储）