Macaroon-like FeCo2O4 modified activated carbon anode for enhancing power generation in direct glucose fuel cell

Macaroon-like FeCo₂O₄ nanomaterial was prepared and used as electrocatalyst in direct glucose alkaline fuel cell (DGAFC), which exhibited high catalytic activity towards glucose oxidation reaction. Maximum power density of 35.91 W m⁻² was achieved in the DGAFC equipped with a FeCo₂O₄ modified activated carbon (AC) anode, which was almost 151% higher than the control. Physical and electrochemical characterizations were performed to provide further understanding of the origin of its high activity. Our results show that the introduction of FeCo₂O₄ into the AC anode remarkably increase the exchange current density and reduce the charge transfer resistance. It is supposed that there is a synergistic effect between Fe (III) and Co (III), which accelerates electron transfer from glucose to external circuits. This study will promote the development of cost effective and environmentally benign catalysts for electrochemical energy applications.     

The rapid selecting of precursor ions and product ions of thirty-four kinds of pesticide for content determination by GC–EI/MS/MS

Pesticide residues caused great threat to human body health, and all countries protected the health of human body by specifying its upper limit. However, pesticide residues were generally very low, similar to trace analysis and as low as millionth or less, the content determination of pesticide residues was a troublesome problem. With the application and promotion of tandem mass spectrometry, it was able to do trace analysis. GC–EI/MS/MS was a common method for the determination of pesticide residues. The multiple reaction monitoring (MRM) mode was the most common quantitative method used in GC–EI/MS/MS. It has the characteristics of high sensitivity, good reproducibility, high accuracy, strong anti-interference and high ion flux. Multiple-twin precursor ions, product ions and collision energy of thirty-four pesticides were provided for MRM. It could play an important role in developing MRM method for the quantifying of 34 kinds of pesticide. Meanwhile, the development of MRM method for the quantifying of other compounds could also refer to this paper.     

鳕鱼骨中可溶性钙提取工艺的优化

以鳕鱼骨为原料,用原子吸收分光光度法测定鳕鱼骨中可溶性钙的含量。采用酸法提取鳕鱼骨中的钙,应用响应面分析法对HCl的浓度、提取温度、反应时间及料液比进行优化。结果表明,鳕鱼骨中可溶性钙提取的最佳工艺条件为HCl浓度3mol/L、提取温度108℃、反应时间60min、料液比1:4(m:V)。该条件下鳕鱼骨中可溶性钙提取率可达22.36%。     

Controlled whey protein aggregates to modulate the texture of fat-free set-type yoghurts

The impact of nanoparticulated whey protein aggregates on the texture of fat-free set-type yoghurts was investigated. Monodisperse (MFA) and polydisperse (PFA) fractal aggregates obtained from heated whey protein isolate (WPI) were added to skimmed milk for yoghurt manufacture at four different concentrations (0.2%–1.5%, w/w). The impact of the concentration and the polydispersity of the aggregates on fat-free set-type yoghurts were studied by instrumental measurements (rheology, penetrometry, syneresis and microscopy) and sensory analysis. Yoghurt gel strength and firmness increased with the concentration of WPI, MFA and PFA. However, yoghurts enriched with PFA clearly differed from the yoghurts enriched with WPI. Indeed, yoghurts enriched with PFA were characterised by a weak gel, a low firmness and a low-density of the protein network. Sensory analysis confirmed the results obtained by instrumental measurements. The whey protein aggregates studied are thus promising tools to modulate fat-free yoghurt texture while using milk-derived ingredients.     

Effects of temperatures and storage time on resting populations of Escherichia coli O157:H7 and Pseudomonas fluorescens in vitro

Assessment of microbial interactions is crucial for documenting bacterial growth in pure and mixed cultures and their potential for biological applications. Pseudomonas fluorescens (non-plant pathogenic and non-pectinolytic) has been used as a biocontrol microbe for plant pathogens and food-borne bacteria. We determined the growth of Escherichia coli O157:H7 (Ec) and P. fluorescens(Pf) in monocultures and co-cultures in sterile distilled water (SDW), buffered peptone water (BPW) and trypticase soy broth (TSB). The effects of temperatures (5, 10, 15, 20, 25, 35, and 37 °C) and storage time (0, 2, 4, 6, 24, and 48 h) on bacteria populations were assessed. Bacteria counts in monocultures in SDW ranged from 2.14 to 3.03 and 2.54 to 3.31 Log CFU/ml for Ec and Pf; respectively. In BPW, mean bacteria counts (monocultures) ranged from 3.15 to 6.14 and 2.54 to 6.41 Log CFU/ml for Ec and Pf, respectively. Ec populations in co-culture varied with storage temperatures and time. After 48 h, Ec 43894 monocultures in TSB ranged from 2.17 to 8.75 and 2.31 to 8.85 Log CFU/ml at 20 and 35 °C; respectively. In co-cultures with Pf 2-79, Ec 43894 counts ranged from 1.71 to 5.83 (20 °C) and 1.90 to 9.03 Log CFU/ml (35 °C) in TSB. The reductions of Ec by Pf 2-79 varied among strains and generally ranged from 0.20 to 0.90, 0.63 to 1.18, and 0 to 0.56 Log CFU/ml in BPW (10 °C). Substrate availability, storage temperatures, and time significantly (P < 0.05) impacted Ec populations in co-culture. The liquid substrate experiments indicated suppressive conditions of Ec by Pf, however; the reduction of produce contamination by E. coli O157:H7 during transitory temperature abuse conditions such as the transportation of produce from fields needs further investigation.     

Low temperature cleanup combined with magnetic nanoparticle extraction to determine pyrethroids residue in vegetables oils

To quantify trace pesticide residue in vegetable oil rapidly, low temperature cleanup combined with magnetic nanoparticle based solid phase extraction was developed to determine eight pyrethroids in vegetable oils, including tetramethrin, fenpropathrin, cypermethrin, decamethrin, fenvalerate, acrinathrin, permethrin and bifenthrin. Polystyrene coated magnetic nanoparticles were synthesised by a modified chemical coprecipitation combined with emulsion polymerisation method. The nanoparticles were afterwards characterised by Fourier transform-infrared spectroscopy, X-ray diffraction, transmission electron microscopy as well as vibrating sample magnetometer, and successfully employed as adsorbents for the magnetic solid phase extraction of pyrethroids which were cleaned up using low temperature approach in advance. Critical impact factors on the efficiency of the extraction method such as the mass of adsorbents used, volume and type of eluent solvent, extraction time as well as elution time were optimised subsequently. Regression analysis of the calibration curves of the eight pyrethroids yielded satisfactory correlation coefficients within the range of 0.980–0.998. Limit of detection and limit of quantification were calculated to be between 0.0290-0.0658 and 0.0890–0.1994 ng g⁻¹, respectively. Intra-day and inter-day reproducibility at different concentration levels also produced satisfactory recovery rates of 83.18–112.79% with relative standard deviations not exceeding 10.84% and 12.01%, respectively, suggesting desirable stability of the proposed method.     

A reliable and sensitive time-resolved fluorescent immunochromatographic assay (TRFICA) for ochratoxin A in agro-products

Immunochromatographic assays (ICAs) are considered as a suitable diagnostic tool for the detection of mycotoxins. Mycotoxins and especially, ochratoxin A are analytes with more demanding sensitivity requirements. To enhance the sensitivity of current immunochromatographic assays for ochratoxin A (OTA), a novel sensitive ICA was developed in this study. In the assay, microspheres enclosing fluorescent europium (III) [Eu(III)] nanoparticles (EuNPs) were used as a label for OTA monoclonal antibody (OTA-mAb) conjugation. Accordingly, assay was called time-resolved fluorescent immunochromatographic assay (TRFICA). The test strip was composed of three parts: a sample pad, nitrocellulose membrane and an absorbent pad. As for detection, a proper concentration of conjugated microspheres was pipetted into the microtube and sample extract was added to it. Then the strip was inserted into the tube and the fluid flow along the strip. The TRFICA results were obtained in 8 min and read by a portable TRFICA strip reader. The established method allows quantitative determination of OTA with limit of detection as low as 1.0 μg kg⁻¹ in the samples. For validation, spiked samples including wheat, maize, soybean and rice were respectively assayed by TRFICA and a standard high performance liquid chromatography equipped with a fluorescence detector (HPLC-FLD), and good agreement of results was obtained between two methods.     

大豆植物提取物的抗炎和镇痛作用研究

目的:研究大豆植物提取物的抗炎、镇痛作用。方法:采用小鼠耳廓肿胀法、大鼠卵白蛋白致足肿胀法、大鼠棉球肉芽肿法、小鼠热板法和小鼠扭体法。结果:大豆植物提取物能抑制二甲苯引起的小鼠耳廓炎性肿胀和大鼠卵白蛋白性足肿胀,并能减轻大鼠棉球肉芽肿重量,说明大豆植物提取物有明显的抗炎作用。镇痛试验表明,大豆植物提取物能显著提高热板试验小鼠的痛阈,有效抑制冰醋酸引起的小鼠扭体反应次数。结论:大豆植物提取物具有抗炎和镇痛作用。