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.     

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.     

Rapid detection method for aflatoxin B1 in soybean sauce based on fluorescent microspheres probe

Soybean sauce, a Chinese traditional and daily condiment, is often contaminated by aflatoxin B₁. An extract-free immunochromatographic assay was proposed based on fluorescent microspheres probe for the' detection of aflatoxin B₁ in soybean sauce. The probe was prepared by coupling fluorescent microspheres with anti-aflatoxin B₁ antibody by the 1-ethyl-3(3-dimethylaminopropyl) carbodiimides hydrochloride-mediated method. The background from the soybean sauce sample on strip was eliminated because of the optical property of the probe. The sample without extracting procedure was directly detected by diluting with 10% methanol solution. The visible detection limit for the qualitative analysis of aflatoxin B₁ in the proposed method was 2.5 μg/L, which was lower than the maximum level of 5 μg/L set by the Chinese government. The results were well agreed with those obtained by liquid chromatography-mass spectrometry (LC-MS). The method showed satisfactory characteristics, such as rapid detection, easy operation, and high sensitivity, and can thus be applied for the large-scale and on-site screening of soybean sauce contaminated with aflatoxin B₁. To our knowledge, this report is the first one on the qualitative detection of aflatoxin B₁ in dark colored food samples directly by fluorescent microspheres probe-based immunochromatography.     

Methods of choosing the optimal parameters for solid fuel combustion in stoker-fired boilers

Stoker-fired boilers are used for the combustion of coal and solid wastes. The most important disadvantage is their low thermal efficiency. The authors present methods of choosing the optimal rate of travel of the grid and height of the fuel layer basing on both realscale and laboratory measurements. Basing on industrial-scale experiments the authors calculated the optimal thermal efficiency and main energy losses using the least squares adjustment method. The stepwise regression method was used to correlate the main energy losses as functions of grid operating parameters. These correlations were used in the optimization method to estimate the optimal rate of travel of the grid and height of the fuel layer. The minimum retention time of the coal can be also calculated.     

Novel monoclonal antibody-based sensitive enzyme-linked immunosorbent assay and rapid immunochromatographic strip for detecting aflatoxin M1 in milk

Monoclonal antibody (mAb) that is specific to AFM1 was generated from the hybridoma cell line, 10F3C10, which was obtained by the fusion of mouse NS1 myeloma cells with the spleen cells of mouse that had been immunized with AFM1-bovine serum albumin (BSA). The 10F3C10 mAb is belong to the immunoglobulin G1 isotype. Both competitive direct and indirect enzyme-linked immunosorbent assay (ELISA) was utilized to characterize the mAb for AFM1. The concentrations of AFM1, AFB1 and AFG1 that caused 50% inhibition (IC₅₀) of the binding of AFM1-horseradish peroxidase (AFM1-HRP) to the antibody were found to be 0.022, 0.310 and 2.12 ng/mL, respectively. The immunochromatographic strip (immunostrip) assay with mAb-gold nanoparticle conjugates as a detection marker exhibited a visual limit of detection of 0.1 ng/mL for AFM1 and the analysis took a total of 10 min. Closely examining 17 milk-based samples using cdELISA revealed that four were slightly contaminated with AFM1 at concentrations from 0.002 to 0.054 ng/mL. All milk samples were negative in the immunostrip test because the levels of contaminant were below the detection limit of the strip. Notably, the presented cdELISA and immunostrip methods are highly sensitive methods for detecting AFM1 in milk.     

A validated strip-based lateral flow assay for the confirmation of sheep-specific PCR products for the authentication of meat

Molecular methods, such as PCR and real-time PCR, have been developed to detect species in meat and meat products. Despite good specificity and sensitivity, they are not widely implemented in food control programs due to complex operation or financial reasons. In the present study, a simple, rapid and affordable method, Sheep-PCR-Strip [Sheep specific polymerase chain reaction-Strip], was developed for the authentic identification of raw and heat-treated mutton. The assay is based on PCR amplification of sheep DNA, followed by detection of the PCR product by a strip format; the result can be read within 5 min by the naked eye. There is a real advantage of the strip approach rather in the reduced time (5 min versus electrophoresis) and avoidance of chemicals (e.g. ethidiumbromide). The sensitivity of the Sheep-PCR-Strip test was established to be 0.01% for the detection of adulterated meat; the limit of detection (LOD) was up to 0.01 pg of sheep DNA. The assay was also specific for sheep, and no cross-reactions were observed in other non-target species. It is a promising new tool for sheep identification and can be rapidly modified for other meat detection and widely used for solving problems related to food quality assurance, species authentication and traceability.     

蚕蛹蛋白多肽对小鼠免疫调节作用的研究

实验观察蚕蛹蛋白多肽对小鼠的免疫调节作用。实验将蚕蛹蛋白多肽分为高、中、低剂量组,分别为5.0、1.7、0.6g/kg bw·d 喂饲小鼠40d,观察小鼠免疫器官指数变化、迟发型变态反应(DTH)、抗体生成细胞数和碳廓清能力等4 个实验项目。实验结果表明：与阴性对照组比较,蚕蛹蛋白多肽能显著增加小鼠胸腺指数,增加小鼠足跖肿胀度,增加小鼠抗体细胞生成数量,增加单核- 巨噬细胞吞噬能力。说明蚕蛹蛋白多肽具有明显的免疫调节作用。     

Sorption equilibrium moisture and isosteric heat of adsorption of Chinese dried wheat noodles

Equilibrium moisture content (EMC) data for dried wheat noodles of ten Chinese varieties were collected by a gravimetric method at 11–96% equilibrium relative humidity (ERH) and 15 °C, 20 °C, 25 °C, 30 °C, and 35 °C. Five models were fitted to the sorption data, namely the modified Chung Pfost equation (MCPE), modified Henderson equation (MHE), modified Guggenheim Anderson deBoer equation (MGAB), modified Oswin equation (MOE), and a polynomial equation. The best fitting equations were MGAB and the polynomial equation. At a constant ERH, the EMC decreased with increasing temperature, despite the minor effect of temperature on the sorption isotherms of dried noodles. Initially, the isosteric heats of adsorption for dried wheat noodles decrease rapidly with increasing sample moisture content (m.c.); however, after the moisture content is more than 15% of the dry basis (d.b.), they decrease slowly with increasing m.c. The heat of vaporization of Chinese dried wheat noodles approaches the latent heat of pure water at a moisture content of ∼20% d.b., which is ∼2500 kJ/kg. The isosteric heats of sorption of Chinese dried noodles predicted by MCPE and MHE models at lower temperatures were higher than those at higher temperatures. When the equilibrium relative humidity (ERH) is 60%, the safe-storage moisture content of Chinese dried wheat noodles are 11.74% and 11.57% d.b. at 25 °C and 35 °C, respectively. Among ten varieties of dried wheat noodles, the egg-flavoured noodle had the highest onset temperature (T_o), peak temperature (T_p), and conclusion temperature (T_c) of gelatinization, but the golden-silk egg noodles had the highest peak enthalpy of gelatinization. The gelatinization T_o, T_p, and T_c of golden-silk egg noodles were the lowest. Most of the ten varieties of dried wheat noodles demonstrated similar thermal properties and hygroscopic behaviour.     

The antimicrobial effects and synergistic antibacterial mechanism of the combination of ε-Polylysine and nisin against Bacillus subtilis

The aim of the present study was to evaluate the combined effects of ε-Polylysine (ε-PL) and nisin and investigate the synergistic action of these compounds against Bacillus subtilis (B. subtilis).The combination of ε-PL and nisin showed synergistic anti-microbial activity against Escherichia coli (E. coli), B. subtilis and Staphylococcus aureus (S. aureus). SEM and TEM microscopy revealed that combined treatment with ε-PL and nisin synergistically damaged the morphology of tested bacterial cells. Propidium iodide (PI) infiltration experiments indicated that combined treatment with ε-PL and nisin synergistically enhanced the permeability of the bacterial cell membrane, likely reflecting the inhibition of both Na⁺K⁺- and Ca⁺⁺ Mg⁺⁺-ATPase activities through these compounds. The fluorescence spectrum showed an interaction between ε-PL and DNA, but not between nisin and DNA. The mode of ε-PL in binding with DNA was similar to that of ethidium bromide (EB). These results indicated that the uptake of ε-PL into cells was promoted through nisin, and subsequently, ε-PL interacted with the intracellular DNA achieving a synergistic effect.