Monitoring unit root and multiple structural changes: An information criterion approach

An information criterion-based model selection method is proposed for monitoring unit root and multiple structural changes. In this method, a battery of possible models is considered by changing the integration order (I(0) or I(1)) and the combinations of change points. Next, the best model is selected from among alternative models via a modified Bayesian information criterion (BIC). Accordingly, on the basis of the selected model, the process that generates the observed time series is determined. The BIC is modified in order to adjust the frequency count of incorrectly selecting stationary models via the conventional BIC. The simulation results of monitoring unit root and structural change suggest that the proposed method outperforms the conventional hypothesis testing method in terms of detection accuracy and detection speed. Furthermore, the empirical results suggest that the proposed method exhibits better performances with regard to detection stability and forecastability.     

Characterisation of zero‐trans margarine fats produced from camellia seed oil,palm stearin and coconut oil using enzymatic interesterification strategy

Zero‐trans interesterified fats were produced from camellia seed oil (CSO), palm stearin (PS) and coconut oil (CO) with three weight ratios (CSO/PS/CO, 50:50:10, 40:60:10 and 30:70:10) using Lipozyme TL IM. Results showed that the interesterified products contained palmitic acid (34.28–42.96%), stearic acid (3.96–4.72%), oleic acid (38.73–47.95%), linoleic acid (5.92–6.36%) and total medium‐chain fatty acids (MCFA)s (∑MCFAs, 5.03–5.50%). Compared with physical blends, triacylglycerols of OOO and PPP were decreased and formed new peaks of equivalent carbon number (ECN) 44 in the interesterified products. The product CPC3′ showed a slip melting point of 36.8 °C and a wide plastic range of solid fat content (SFC) (45.8–0.4%) at 20–40 °C. Also, the major β′ form was determined. These data indicated that the zero‐trans interesterified fats would have a potential functionality for margarine fats. Subsequently, the antioxidative stabilities of interesterified products with the addition of α‐tocopherol (α‐TOH) and ascorbyl palmitate (AP) were investigated. The results indicated that AP had a dose‐dependent effect at concentrations of 100, 200 and 400 ppm.     

Influence of ultrasonic treatment on the structure and emulsifying properties of peanut protein isolate

Effects of ultrasonic treatment on emulsifying properties and structure of peanut protein isolate (PPI) were evaluated by analysis of particle size distribution, protein surface hydrophobicity, SDS-PAGE, circular dichroism spectra and environmental scanning electron microscopy. The emulsifying properties of the PPI were found to be improved by ultrasonic treatment. The mean particle size decreased from 474.7 nm to 255.8 nm while the molecular weight remained unaffected. The results of intrinsic fluorescence spectroscopy and surface hydrophobicity indicated that ultrasonic treatment induced tertiary structural changes of the proteins in PPI. Emulsifying activity index and emulsion stability index were found to be correlated fairly well with surface hydrophobicity (H₀) (r = 0.712 and r = 0.668, respectively).     

超声波辅助提取藜蒿多酚工艺优化及抗氧化活性研究

以藜蒿为原料,采用超声波辅助法提取藜蒿多酚,研究其最佳提取工艺及体外抗氧化活性。结果表明:超声波辅助提取藜蒿多酚的最佳条件为:液固比20:1(mL/g),提取次数2次,乙醇浓度30%(v/v),超声功率200W,提取时间80min,提取温度80℃,在此条件下,多酚得率为1.858%±0.023%。体外抗氧化实验表明:藜蒿多酚粗提液(PAST)的抗氧化能力随多酚浓度的增加而增强,当多酚浓度大于148.80μg/mL时,PAST对DPPH.的清除能力高于BHA而与没食子酸相当;还原能力顺序为:没食子酸>PAST>BHA,在实验浓度范围内,PAST的还原能力相当于BHA的1.24～1.33倍。     

Recent developments in Hericium erinaceus polysaccharides: extraction,purification, structural characteristics and biological activities

Abstract

Hericium erinaceus (H. erinaceus), an edible mushroom with medicinal value, has a long history of usage in China and other oriental countries. Polysaccharide is supposed to be one of the major bioactive compounds in H. erinaceus, which possesses immunomodulating, anti-cancer, antioxidant, gastroprotection and intestinal health promotion, neuroprotective, hepatoprotective, antihpyerglycemic and hypolipidemic activities. In this review, the current advancements on extraction, purification, structural characteristics and biological activities of polysaccharide from different sources (fruiting body, mycelium and culture broth) of H. erinaceus were summarized. Among these aspects, summaries of the structural characteristics focused on the purified polysaccharides. Meanwhile, comparisons on the structural characteristics among the purified polysaccharides obtained from above three sources were made. Moreover, their biological activities were introduced on the basis of in vivo and in vitro experiments, and some possible action mechanisms were listed. Furthermore, the structure-activity relationship of the polysaccharide was discussed. New perspectives for the future work of Hericium erinaceus polysaccharide were also proposed.

• HIGHLIGHTS

• Extraction, purification, structural characteristics and biological activities of Hericium erinaceus polysaccharide (HEP) were summarized.

• Structural characteristics of the purified polysaccharides from different sources (fruiting body, mycelium and culture broth) of Hericium erinaceus were summarized and compared.

• Structure-activity relationship of HEP was discussed, and new perspectives for the future work of this polysaccharide were proposed.

     

The protective effect of monosodium glutamate on survival of Lactobacillus rhamnosus GG and Lactobacillus rhamnosus E-97800 (E800) strains during spray-drying and storage in trehalose-containing powders

The use of trehalose as a means of preserving Lactobacillus rhamnosus GG (LGG) and L. rhamnosus E-97800 (E800) during spray-drying and the effects of incorporated monosodium glutamate (MSG) in the carrier medium on the survival rates during drying and storage were examined. E800 was more resistant to heat than LGG in 20%, w/w, trehalose; the d-values at 65 °C were 14 s and 5.1 s, respectively. An air outlet temperature of 65–70 °C was taken as optimal for the drying process, as the resultant moisture levels in trehalose containing these bacteria were 4.1% (w/w) and 3.79% (w/w) with corresponding viable counts of 3.65 × 10⁸ cfu mL^?1 and 1.80 × 10⁹ cfu mL^?1, respectively. The presence of MSG increased the final viable counts of LGG and E800 to 3.05 × 10⁹ cfu mL^?1 and 1.30 × 10⁹ cfu mL^?1, respectively. Survival of LGG and E800 remained constant at a minimum level of ～10⁸ cfu mL^?1 during storage at 25 °C in trehalose–MSG medium.     

An ELIME-array for detection of aflatoxin B1 in corn samples

The aim of the present work was the development of an ELIME-array to achieve simple and rapid detection of AFB₁ in corn samples. The system is based on an indirect competitive ELISA format using magnetic beads as immobilisation support and eight magnetised screen-printed electrodes as electrochemical transducers.After an optimisation study, a corn sample treatment, employing an extraction in acetonitrile/water followed by a clean-up step and solvent evaporation, was selected.For the construction of the calibration curve, which was used to evaluate both evaluation of the matrix effect on the performances of the ELIME-array and for the analysis of Certified Reference Materials (CRMs), standard solutions of AFB₁ were added to blank dried corn extracts reconstituted in PBS. The detection limit and the sensitivity of the assay were calculated to be 0.6 ng mL^?1 and 1.5 ng mL^?1, respectively.Precision (11–26%) and recovery (95–114%) data of the ELIME-array, determined by analysing four CRMs, have shown that the proposed system appears suitable as a screening tool for the analysis of AFB₁ in corn samples.     

Effect of metal additives on the catalytic performance of Ni/Al2O3 catalyst in thermocatalytic decomposition of methane

Thermocatalytic decomposition of methane is proposed to be an economical and green method to produce CO_x-free hydrogen and carbon nanomaterial. In present work, 60 wt% Ni/Al₂O₃ catalysts with different additives (Cu, Mn, Pd, Co, Zn, Fe, Mg) were prepared by co-impregnation method to investigate promotional effects of these metal additives on the activity and stability of 60 wt% Ni/Al₂O₃ and find out a really effective promoter for decomposition of methane. The catalyst was characterized by N₂ adsorption/desorption, X-ray diffraction, scanning electron microscopy, inductively coupled plasma optical emission spectrometer and hydrogen temperature programmed reduction. While metal additives (5 wt%) were added into 60 wt% Ni/Al₂O₃, the activity stability of 60 wt% Ni/Al₂O₃ was improved and the CH₄ conversion of 60 wt% Ni/Al₂O₃ was also improved except Zn addition. Mn addition was found to improve the catalytic activity of 60 wt% Ni/Al₂O₃ significantly and the CH₄ conversion of 5 wt% Mn-60 wt% Ni/Al₂O₃ was ∼80%. Cu addition was found to remarkably improve the catalytic stability of 60 wt% Ni/Al₂O₃ and the CH₄ conversion of 5 wt% Cu-60 wt% Ni/Al₂O₃ decreased from 61% to 45% after 250 min of reaction time. Carbon nanomaterials formed in the thermocatalytic decomposition process were characterized by X-ray diffraction, scanning electron microscopy, thermal gravimetric analyzer and Raman spectroscopy. Carbon deposits consist of amorphous carbon and carbon nanofibers.     

Hydrazine hydrate-induced hydrothermal synthesis of MnFe2O4 nanoparticles dispersed on graphene as high-performance anode material for lithium ion batteries

Herein, a MnFe₂O₄/graphene (MnFe₂O₄/G) nanocomposite has been synthesized via a facile N₂H₄·H₂O-induced hydrothermal method. During the synthesis, N₂H₄·H₂O is employed to not only reduce graphene oxide to graphene, but also prevent the oxidation of Mn²⁺ in alkaline aqueous solution, thus ensuring the formation of MnFe₂O₄/G. Moreover, MnFe₂O₄ nanoparticles (5–20 nm) are uniformly anchored on graphene. MnFe₂O₄/G electrode delivers a large reversible capacity of 768 mA h g⁻¹ at 1 A g⁻¹ after 200 cycles and high rate capability of 517 mA h g⁻¹ at 5 A g⁻¹. MnFe₂O₄/G holds great promise as anode material in practical applications due to the outstanding electrochemical performance combined with the facile synthesis strategy.