ACS Applied Materials & Interfaces
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2016
·
IF 7.145
Anran Chen,Liang Xu,Xiaojing Zhang,Zhimao Yang,Shengchun Yang
α-Fe2O3 nanoparticles (NPs) with morphologies varying from shuttle to drum were synthesized through an anion-assisted and surfactant-free hydrothermal method by simply varying the ratios of ethanol and water in solvent. Control experiments show that the structural evolution can be attributed to a small-molecular-induced anisotropic growth mechanism in which the growth rate of α-Fe2O3 NPs along the a-, b-, or c-axis was well-controlled. The detailed structural analysis through the high-resolution transmission electron microscope (HRTEM) indicated that shuttle-like Fe2O3 NP surface was covered by high-density atomic steps, which endowed them with the enhanced adsorption and sensor ability toward dopamine (DA). The XPS characterizations indicated that the percentages of the OC component follow the order of shuttle-like Fe2O3 (S-Fe2O3 for short) > pseudoshuttle-like Fe2O3 (Ps-Fe2O3 for short) > polyhedron-like Fe2O3 (Ph-Fe2O3 for short) > drum-like Fe2O3 (D-Fe2O3 for short). Benefits from these structural advantages, the S-Fe2O3 NPs–Nafion composite electrode exhibited remarkable electrochemical detection ability with a wide liner range from 0.2 μM to 0.107 mM and a low detection limit of 31.25 nM toward DA in the presence of interferents.
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JOURNAL OF MEMBRANE SCIENCE
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2016
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IF 5.557
Dong Zou,Minghui Qiu,Xianfu Chen,Yiqun Fan
Compared to the traditional separation technology, membrane separation is particular beneficial for the treatment of contaminated fresh water such as agricultural runoff, and hydraulic fracturing wastewater. However, the development of cost-effective membranes with both high permeability and high rejection performance is still a challenge. In this study, we design one-step preparation of high-performance bi-layer α-alumina ultrafiltration (UF) membranes supported on coarse tubular substrates via co-sintering process. In this approach, boehmite sol and alumina nanoparticles were mixed in different ratios for the fabrication of microfiltration (MF) layer and UF layer, respectively. The effects of dip-coating dispersion formulation, coating time and thermal treatment process on the membrane microstructure and performance were comprehensively investigated. It was found that the presence of boehmite sol in the MF layer could accelerate its sintering process, while the addition of alumina nanoparticles into UF layer could promote the phase transition from γ phase to α phase at low temperature and retard the shrinkage. The optimized doping content of boehmite and alumina nanoparticles were 2 wt% and 4 wt% to achieve a good match of thermal expansion properties between the two co-sintering layers. For MF layer and UF layer, the membrane thickness were controlled to be 40–50 µm and about 1 µm, respectively. After co-sintering at 1000 °C for 2 h with a heating rate and cooling rate of 0.5 °C/min, tubular α-alumina UF membranes were found to display a high pure water permeability of 70 L m -2 h -1 bar -1 and a small pore size of ~5 nm, which also exhibited good dye removal capabilities in the process of treating dye waste water.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2016
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IF 3.138
Hong Niu,Dan Song,Yuelin Sun,Wuxia Zhang,Haibo Mu,Jinyou Duan
In this study, one homopolysaccharide (ACPA1) with a molecular weight (Mw) of 5.5 × 10 3 g/mol was prepared from the roots of Actinidia chinensis . It was characterized as an α- d -glucan consisting of predominant 4-linked α- d -Gl cp residues branched at O-6. Three sulfated derivatives of ACPA1 (SA1, SA2 and SA3) with different degrees of sulfation (DS) were obtained by SO 3 -pyridine procedure. Moisture-preserving tests demonstrated that the sulfated derivatives with the highest DS values, SA1 and SA2, exhibited better moisture-preserving abilities than ACPA1 and SA3. All sulfated derivatives exerted stimulatory effects on phagocytosis activity and nitric oxide production by RAW 264.7 macrophages while ACPA1 did not. These findings suggested that the sulfated derivatives of ACPA1 might be used as moisture-preserving or immunopotentiating reagents.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
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2016
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IF 1.835
Kewen Tang,Xiaofeng Feng,Panliang Zhang,Weifeng Xu
Liquid–liquid extraction (LLE) was used for the resolution of α-cyclopentylmandelic acid (α-CPMA) enantiomers, in which environmentally friendly and economical hydroxyethyl-β-cyclodextrin (HE-β-CD) was screened as the optimal selector. The mechanism on equilibrium of the separation system was proposed. Influence of important parameters on the separation performance of α-CPMA enantiomers were investigated (e.g., kinds of solvents for the organic phase, types and concentration of selector, pH of extraction phase, temperature). On the basis of the mechanism proposed, a quantitative model was also built to simulate the separation process. Results show that the model predicts the experimental data accurately and it is further used for optimizing the separation process. The optimized process conditions consist of 1,2-dichloroethane as organic solvent, pH = 2.5 and the extractant concentration of 0.04 mol·kg–1. Under the optimum conditions, the enantioselectivity toward α-CPMA enantiomers is over 1.70 and performance factor is 0.07.
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PROTEIN JOURNAL
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2016
·Vol. 35
·期 2
·154-162
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IF 1.029
Tian Mei-ling,Fang Ting,Du Mu-ying,Zhang Fu-sheng
To explore an efficient, safe, and speedy application of pulsed electric field (PEF) technology for enzymatic modification, effects of PEF treatment on the enzymatic activity, property and kinetic parameters of α-amylase were investigated. Conformational transitions were also studied with the aid of circular dichroism (CD) and fluorescence spectra. The maximum enzymatic activity of α-amylase was obtained under 15 kV/cm electric field intensity and 100 mL/min flow velocity PEF treatment, in which the enzymatic activity increased by 22.13 ± 1.14 % compared with control. The activation effect could last for 18 h at 4 °C. PEF treatment could widen the range of optimum temperature for α-amylase, however, it barely exerted any effect on the optimum pH. On the other hand, α-amylase treated by PEF showed an increase of V
max , t 1/2 and Δ G , whereas a decrease of K
m and k were observed. Furthermore, it can be observed from fluorescence and CD spectra that PEF treatment had increased the number of amino acid residues, especially that of tryptophan, on α-amylase surface with enhanced α-helices by 34.76 % and decreased random coil by 12.04 % on α-amylase when compared with that of untreated. These changes in structure had positive effect on enhancing α-amylase activity and property.
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Journal of Physical Chemistry C
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2016
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IF 4.509
Yajie Xu,Lingli Liu,Hanbao Chong,Sha Yang,Ji Xiang,Xiangming Meng,Manzhou Zhu
AuPt alloy nanoparticles (NPs) were facilely synthesized with oleylamine as the stabilizing ligand and characterized by high-resolution transmission electron microscopy, powder X-ray diffraction, inductively coupled plasma-atomic emission spectrometer analysis, and so on. In addition, the AuPt alloys supported by the nano CeO2 exhibit high selectivity and efficiency in hydrogenation of benzylidene acetone under ambient temperature and pressure. By analyzing the catalytic performance over the NPs with different Au:Pt compositions, we found that the TONPt values (based on the number of Pt atoms) vary in the same trend with the change of conversion. Despite that gold itself shows no catalytic activity, the improved conversion and TONPt with the alloy catalysts clearly show the promotion effect of gold on the catalytic activity of the platinum. The inactive metal significantly improves the catalytic activity of active metal, which shows that the AuPt alloy exhibits an interesting synergistic effect.
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CARBOHYDRATE POLYMERS
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2016
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IF 4.219
Jianfang Jiang,Yongzheng Chen,Wei Wang,Baodong Cui,Nanwei Wan
In order to improve catalytic activity, increase recycling times, reduce use cost for enzyme, superparamagnetic carboxymethyl chitosan/sodium alginate nanosphere (SM/CMC/SA) has been synthesized via an improved hydrothermal method, molecular self-assembly technology, electrostatic interaction and amide linkage. Its mean diameter was 65 nm, zeta potential was −36.9 mV and BET was 53.8 m 2 /g. α-Amylase was selected as a simulation object to manufacture an immobilized enzyme (SM/CMC/CA/α-Amy), and its catalytic activity, release behavior, reusability and stability were researched. Immobilization increased 4.67 times to catalytic activity, slowed down release rate and improved reusable performance. SM/CMC/CA/α-Amy showed higher activity over a wider pH range, especially in strong acidic and alkaline environments. The thermal stability and storage stability were improved remarkably too. All these results indicated that SM/CMC/SA was an ideal carrier for immobilizing enzyme.
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JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
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2015
·Vol. 78
·期 2
·293-298
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IF 1.532
Cui Hongtao,Ma Wenle,Wang Li,Xue Junying
Abstract
In this work, α-Co(OH) 2 monolayer nanosheets were prepared by an intercalation agent-free route utilizing a precipitation reaction between epoxide and aqueous complexes of cobalt ions ([Co(H 2 O) 6 ] 2+ ). The protonation and the following ring-opening reaction of epoxide promoted the hydrolysis of [Co(H 2 O) 6 ] 2+ , leading to the formation of α-Co(OH) 2 nanosheets. The obtained nanosheets were then exfoliated to monolayer nanosheets in formamide under ultrasonic vibration. A possible exfoliation mechanism is proposed for the exfoliating process of α-Co(OH) 2 nanosheets. The water molecules incorporated in the layered structure of α-Co(OH) 2 are considered to be the key medium for the layer exfoliation. It seems that the water molecules coordinated with the cobalt ions weakened the interlayer interaction. Therefore, the extraction of water molecules by formamide readily broke the interlayer connection in α-Co(OH) 2 , resulting in the exfoliation of nanosheets. Graphical Abstract α-Co(OH) 2 monolayer nanosheets were prepared by an intercalation agent-free route utilizing a precipitation reaction between epoxide and aqueous complexes of cobalt ions ([Co(H 2 O) 6 ] 2+ ).
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MACROMOLECULES
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2016
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IF 5.554
Ye Sha,Yunlong Xu,Dongliang Qi,Yuanxin Wan,Linling Li,Hong Li,Xiaoliang Wang,Gi Xue,Dongshan Zhou
We report on the synthesis of heterotelechelic α,ω-dye-labeled polystyrene and poly(methyl methacrylate) via a combination of site-specific atom transfer radical polymerization (ATRP) and click chemistry. By using the advantages of the living polymerization characteristics and a robust coupling efficiency, the Förster/fluorescence resonance energy transfer (FRET) pairs (i.e., carbazolyl and anthryl) were dictated to be at the near-stoichiometric chain ends. The distribution of the end-to-end distance was well described by the energy transfer response of the fluorescent groups between chain ends, which is in reasonable agreement with Gaussian statistics. The synthetic approach described here provides an opportunity to prepare polymeric materials with customized responsive elements and in-depth insight into the statistical scaling dimension of polymers.
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JOURNAL OF FOOD SCIENCE
·
2015
·Vol. 80
·期 6
·C1156
·
IF 1.696
Benguo Liu,Yun Li,Huizhi Xiao,Yonglan Liu,Haizhen Mo,Hanjun Ma,Guizhao Liang
en This link goes to a English section pt This link goes to a English section Polydatin is the main bioactive ingredient in many medicinal plants, such as Hu-zhang ( Polygonum cuspidatum ), with many bioactivities. However, its poor aqueous solubility restricts its application in functional food. In this work, 6-O-α-Maltosyl-β-cyclodextrin (Malt-β-CD), a new kind of β-CD derivative was used to enhance the aqueous solubility and stability of polydatin by forming the inclusion complex. The phase solubility study showed that polydatin and Malt-β-CD could form the complex with the stoichiometric ratio of 1:1. The supermolecular structure of the polydatin/Malt-β-CD complex was characterized by ultraviolet–visible spectroscopy (UV), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), thermogravimetric/differential scanning calorimetry (TG/DSC), and proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy. The changes of the characteristic spectral and thermal properties of polydatin suggested that polydatin could entrap inside the cavity of Malt-β-CD. Furthermore, to reasonably understand the complexation mode, the supermolecular structure of polydatin/Malt-β-CD inclusion complex was postulated by a molecular docking method based on Autodock 4.2.3. It was clearly observed that the ring B of polydatin oriented toward the narrow rim of Malt-β-CD with ring A and glucosyl group practically exposed to the wide rim by hydrogen bonding, which was in a good agreement with the spectral data. Practical Application en This link goes to a English section pt This link goes to a English section Polydatin was a nutraceutical with potential prospect in functional food. In this study, 6-O-α-Maltosyl-β-cyclodextrin, a new kind of β-CD derivative was used to improve its poor aqueous solubility by forming the inclusion complex, which can be used to develop new functional food. The introduced spectral technologies and molecular docking method could be used to characterize other complexes of bioactive compounds with CDs.
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CARBOHYDRATE POLYMERS
·
2013
·
IF 3.479
Yun Lu,Qingfeng Sun,Xilin She,Yanzhi Xia,Yixing Liu,Jian Li,Dongjiang Yang
α-Chitin nanofibers were fabricated with dried shrimp shells via a simple high-intensity ultrasonic treatment under neutral conditions (60 KHz, 300 W, pH = 7). The diameter of the obtained chitin nanofibers could be controlled within 20–200 nm by simply adjusting the ultrasonication time. The pulsed ultrasound disassembled natural chitin into high-aspect-ratio nanofibers with a uniform width (19.4 nm after 30 min sonication). The EDS, FTIR, and XRD characterisation results verified that α-chitin crystalline structure and molecular structure were maintained after the chemical purification and ultrasonic treatments. Interestingly, ultrasonication can slightly increase the degree of crystallinity of chitin (from 60.1 to 65.8). Furthermore, highly transparent chitin films (the transmittance was 90.2% at a 600 nm) and flexible ultralight chitin foams were prepared from chitin nanofiber hydrogels.
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Nanoscale
·
2013
·Vol. 5
·期 17
·8114-8121
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IF 6.233
Wei Zhang,Lanlan Zhai,Na He,Chao Zou,Xiaozhen Geng,Lujun Cheng,Youqing Dong,Shaoming Huang
Cu2ZnSnS4 is a promising solar absorbing material in solar cells due to its high absorption coefficient and abundance on earth. We have demonstrated that wurtzite Cu2ZnSnS4 nanoleaves could be synthesized through a facile solution-based method. Detailed investigation of the growth process indicates that α-Cu2S nanocrystals are first formed and then serve as a catalyst to introduce the Cu, Zn, and Sn species into the nanoleaf growth for fast ionic conduction. The structure of the as-synthesized nanoleaves is characterized by powder X-ray diffraction, high-resolution transmission electron microscopy, fast Fourier transform, and energy dispersive X-ray spectroscopy mapping. Photoresponses of Cu2ZnSnS4 nanoleaves are evaluated by I–V curves of a Cu2ZnSnS4 nanoleaf film. It is believed that the enhancement of the photoresponse current of the Cu2ZnSnS4 nanoleaf film can be attributed to fast carrier transport due to the single crystalline nature and enhanced light absorption resulting from larger absorption areas of the Cu2ZnSnS4 nanoleaves.
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