动力学模型在鱼肉品质变化中的应用

考察了不同温度下鱼肉贮藏过程中细菌总数、挥发性盐基氮值随存放时间的变化规律及其动力学特性;建立了细菌总数、挥发性盐基氮值与贮藏温度和时间的动力学模型。贮藏过程中鱼肉的细菌总数、挥发性盐基氮值随贮藏时间的延长而增加,随贮藏温度的增加而上升。细菌总数和挥发性盐基氮值对一级化学反应模型和Arrhenius方程具有较高的拟合精度。     

A new amperometric biosensor for hydrogen peroxide determination based on HRP-nanogold-PTH-nanogold-modified carbon paste electrodes

A new strategy for immobilization of horseradish peroxidase (HRP) has been developed by self-assembling gold nanoparticles to multiporous polythionine (PTH) film modified carbon paste interface. A thionine film was initially electropolymerized onto carbon paste interface in a mildly acidic thionine solution at a bias voltage of −1.0 to 1.5 V. This process is accompanied by the hydrogen evolution reaction, and the released hydrogen gas made the PTH film with multiporous structure. The multiporous PTH film provided a biocompatible microenvironment for gold nanoparticles and enzyme molecules, and greatly amplified the coverage of HRP molecules on the electrode surface. Voltammetric and time-based amperometric techniques were employed to characterize the properties of the derived biosensor. The performance and factors influencing the performance of the biosensor were also proposed. The immobilized HRP displayed a catalytic property to the reduction of H₂O₂. The H₂O₂ biosensor achieved 95% of the steady-state current within 2 s, and exhibited a linear range of 9.6×10⁻⁶ to 1.2×10⁻³ M H₂O₂ with a detection limit of 7.5×10⁻⁷ M (S/N = 3). Furthermore, the biosensor remained at about 90% of its original sensitivity after 2 weeks’ storage.     

L-亮氨酸产生菌的选育及其发酵条件优化

以黄色短杆菌TQ980 6(Met- +IleL+2 TAr+α ABr+β HLr+SGr+Rifr3 0 0 μg/mL)为出发菌株 ,经硫酸二乙酯、紫外线分别与LiCl复合诱变 ,选育出一株利福平抗性为 80 0 μg/mL的L 亮氨酸产生菌TK0 3 0 3。通过对其摇瓶发酵条件的研究和优化 ,产量由出发菌株TQ980 6的 2 2 7g/L提高至目的突变株TK0 3 0 3的 2 8 3g/L。     

Overview of pharmacological activities of Andrographis paniculata and its major compound andrographolide

Abstract

Andrographis paniculata (A. paniculata) is a medicinal plant traditionally used as anti-inflammation and anti-bacteria herb. Andrographolide, the major active component of A. paniculata, exhibits diverse pharmacological activities, including anti-inflammation, anti-cancer, anti-obesity, anti-diabetes, and other activities. In this article, we comprehensively review the therapeutic potential of A. paniculata and andrographolide focusing on the mechanisms of action and clinical application. We systemically discuss the structure-activity relationship of andrographolide and derivatives. Despite the various pharmacological activities and formula of A. paniculata and andrographolide, we propose further development of more structural derivatives of andrographolide with reduced toxicity and increased therapeutic efficacy is still needed for the clinical application of this ancient mighty herb and its major component.     

食品添加剂红曲红中桔霉素检测方法的研究

食品添加剂红曲红中桔霉素限量问题已成为近年来国内外研究热点。目前,国内缺乏专门针对红曲红色素中桔霉素检测的标准方法。文中在综合分析国内外相关桔霉素检测方法技术资料的基础上,通过试验,对粉状样品预处理条件进行了优化,研究了适合我国生产的红曲红色素中桔霉素检测方法。粉状红曲红样品先用体积分数50%乙醇配制成一定浓度的试样液,试样液在优化的树脂分离条件下进行洗脱,然后采用高效液相色谱法测定洗脱液中的桔霉素含量。实验结果显示:优化的树脂分离条件能较好地洗脱样品中的桔霉素;配有荧光检测器的高效液相色谱仪能较灵敏地检出桔霉素含量,方法检测限为0.2μg/L,基质加标平均回收率为105.5%,相对标准偏差(RSD)为2.2%。     

Electrochemical sensor based on Prussian blue nanorods and gold nanochains for the determination of H<Subscript>2</Subscript>O<Subscript>2</Subscript>

In this paper, a novel electrochemical sensor for the detection of H₂O₂ was proposed based on gold nanochains and prussian blue nanorods (PB@MWCNTs), which were synthesized with multiwall carbon nanotubes (MWCNTs) as a template. With the introduction of MWCNTs and the gold nanochains, the proposed system shows synergy among the Prussian blue (PB), MWCNTs, and the gold nanochains, which amplifies the H₂O₂ sensitivity greatly. A linear range from 1.75 × 10⁻⁶ to 1.14 × 10⁻³ M with a detection limit of 0.5 × 10⁻⁶ M (S/N = 3) and a high sensitivity 300 μA mM⁻¹ cm⁻² for H₂O₂ detection is obtained. Moreover, the sensor exhibits good repeatability and stability.     

液比对尾叶桉硫酸盐法制浆过程中脱木素的影响

本文以尾叶桉为原料,研究了液比对其在硫酸盐法蒸煮过程中脱木素的影响;在此基础上,建立了基于蒸煮液比、纸浆修正卡伯值预测溶解木素量的数学方程,即CLS=1.94(45-KappaM)(L-1.8)+136。结果表明:在蒸煮前期(保温15min前),相同卡伯值条件下,液比变化对溶解木素的扩散几乎无影响;在蒸煮后期(保温15min后),相同卡伯值下,液比越小木素溶出量随之减少。     

硼对烤烟生理生化及产质量的影响

本试验对烤烟的Ｂ＾３＋肥效应进行了研究。结果表明,施用适量的Ｂ＾３＋,可促进烤烟生长发育,改善其植物学性状,增加色素含量,提高光合强度和蒸腾速率,使烟叶增产、增质、增收。同时还发现Ｂ＾３＋能使烟株提前２～３ｄ现蕾开花,中下部烟叶提前落黄采收。这一特性,对烤烟生产具有重要的作用。     

植物乳杆菌亚油酸异构酶的分离纯化及其性质研究

经硫酸铵分级沉淀、阴离子交换层析和凝胶过滤,由植物乳杆菌(LactobacillusplantarumL 2 9)分离纯化得到亚油酸异构酶,分子量为4 3ku。对其酶学性质进行研究,结果表明,温度37℃、pH 6 0时酶活性较高;Co2 + 、Fe2 + 可提高酶的活性,Cu2 + 、Zn2 + 则对酶活力有抑制作用;该酶作用于亚油酸的Km=2 5 3×10 -5mol/L ,Vmax=2 5 7×10 -8mol/ (min·mg)。