The Stabilizing Effects of Polyols and Sugars on Porcine Pancreatic Lipase

Porcine pancreatic lipase (PPL) has been used as a biocatalyst for many years and is one of the most widely used enzymes for biotechnological applications; however, it is a rather complex mixture with various active enzymes. The present study has been undertaken to determine the effects of polyols and sugars (cosolvents) on the thermal stability of PPL preparation. The thermal stability of PPL exposed to 60°C for 10 min was enhanced in the presence of cosolvents in terms of both residual specific activity and conformational stability. Thermal denaturation, changes in circular dichroism, fluorescence spectra, apparent kinetic parameters, activity, and preferential interaction parameter of PPL preparation are discussed in terms of contributions to the mechanism of thermal stability and the activity enhancement. Partial specific volume measurement of PPL in the presence of cosolvents is presented for the first time. The preferential interaction parameter (ξ ₃) was negative in all cosolvents used, and maximum hydration was observed in the presence of trehalose, where the preferential interaction parameter was −0.076 g/g. The observed increase in the thermal stability of PPL preparation in the presence of cosolvents is due to the preferential hydration of the enzyme.     

测定ATP以确定微生物活力

ATP 即三磷酸腺苷(Adenosine Triphosphate),它是活细胞普遍具有的组分,是所有生物活动的直接能源,是生命活力的标志。ATP 对活物质之此相对为常数。外界条件的变化如温度、pH、供氧、重金属、有毒化合物等都会影响ATP含量。所以,测定ATP 可以确定微生物的活力。测出ATP 并对比其变化,可以在微生物学及废水生物处理的理论和应用中作为一个指标,说明很多问题。ATP 一经与萤火虫提取物混合即产生闪光,且光量与ATP 含量成正比。据此原理即可进行ATP 定量测定。本文分基本原理、应用和测定方法三部分对该题加以较详细的论述。     

TiO2光催化抗菌材料

介绍了ＴｉＯ２光催化材料的抗菌与杀菌原理、特点及提高其杀菌性能的方法。并对其应用前景作了简要评述。     

Ageing behavior of acrylic polyurethane varnish coating in artificial weathering environments

Polyurethane-based coatings reinforced by ZnO nanoparticles (about 27 nm) were prepared via solution blending. The ZnO/PU films and coats were fabricated by a simple method of solution casting and evaporation. The mechanical properties of the films were investigated by a universal material test, and the abrasion resistance of the prepared coats was evaluated by a pencil-abrasion-resistance tester. It was found that significant improvement of the PU films in Young’s modulus and tensile strength was achieved by incorporating ZnO nanoparticles up to 2.0 wt%, and that the abrasion resistance of the PU coats was greatly enhanced due to the addition of ZnO nanoparticles. Moreover, the antibacterial property test was carried out via the agar dilution method and the result indicated that PU films doped with ZnO nanoparticles showed excellent antibacterial activity, especially for Escherichia coli.     

LB energy-saving high temperature shift catalyst and its adsorption thermodynamics

This study prepared an LB energy-saving high temperature shift catalyst by optimizing its prepare parameters with artificial neural network, and measured its catalytic activities at various steam-gas ratios. It shows that the LB catalyst performs well at a lower steam-gas ratio. The chromatographic retention parameters of CO, CO₂, and H₂O on LB catalyst were experimentally determined by means of inverse gas chromatography (IGC). Adsorption enthalpies, Gibbs adsorption free energies and adsorption entropies of different gases were estimated by their retention volumes in infinite dilution region. The interaction parameters (χ) between absorbate gases and LB catalyst were calculated according to Flory-Huggins theory, and were inversely linear with temperature. The thermodynamics mechanism of the adsorption process was discussed from the view of the microcosmic factors of molecular structure and thermodynamic properties.     

Enviro-Friendly Synthesis of Silver Nanoparticles Using Berberis lycium Leaf Extract and Their Antibacterial Efficacy

In the present study,an enviro-friendly synthesis of silver nanoparticles from Berberis lycium Royle leaf extract and their antibacterial efficacy against five pathogenic bacteria were investigated.This biosynthesis technique is proved to be advantageous over physical and chemical methods as no toxic chemicals are used.The structural and morphological characterization was made by UV-visible spectroscopy,scanning electron microscopy,and transmission electron microscopy.The synthesized nanoparticles were oval,rectangular,and spherical in shape,size ranges from 8 to 100 nm and exhibited an absorption peak at 458 nm.The biosynthesized silver nanoparticles have shown good antibacterial effect toward tested bacteria.It is believed that these biosynthesized silver nanoparticles can play a vital role in nano-based products in future.     

四针状氧化锌晶须对聚丙烯力学性能及抗菌性能的影响

采用偶联剂KH-570对四针状氧化锌晶须(T-ZnOw)进行表面改性,制备了聚丙烯(PP)/改性T-ZnOw复合材料。对复合材料进行了X射线衍射分析,并考察了T-ZnOw含量对复合材料力学性能和抗菌性能的影响。结果表明:T-ZnOw在PP基体中结晶良好;适量添加经过表面改性的T-ZnOw能提高复合材料的拉伸强度、断裂伸长率和弯曲强度;在T-ZnOw含量为4%时,复合材料即可达到国家规定的抗菌要求。     

Vapor Pressure of Water in Mixtures with Hydrophilic Ionic Liquids – A Contribution to the Design of Processes for Drying of Gases by Absorption in Ionic Liquids

The low water vapor pressures of mixtures of water with the ionic liquids (ILs), [EMIM][EtSO₄] and [BEIM][EtSO₄], indicate that a process of gas dehydration by absorption in ILs might be an alternative to the classical absorption process with triethylene glycol (TEG). The activity coefficient for an infinite dilution of water in the IL (x_IL → 1), which should be low for efficient dehydration, is only about 0.2 for [EMIM][EtSO₄] compared to 0.6 for triethylene glycol. In contrast to TEG, losses by evaporation are excluded with ILs as solvents, because they have a negligible vapor pressure. The number of separation stages needed for the absorption in the IL and for the subsequent regeneration of the water‐loaded IL is small, about six and eight, respectively. IL regeneration can be achieved by distillation of water out of the IL (e.g., at 120 °C) and stripping with ambient air, which is not possible in the case of TEG (chemical attack by O₂).     

抗ICAM-1单克隆抗体的制备及其活性

目的制备具有生物活性的抗人细胞间黏附分子-1(ICAM-1)单克隆抗体。方法以人ICAM-1为抗原免疫BALB/c小鼠,采用杂交瘤技术并经HAT选择培养和克隆化,筛选出稳定分泌抗人ICAM-1 McAb的杂交瘤细胞株,并对McAb进行纯化。用ELISA间接法测定效价并鉴定其亚类,Western blot鉴定其抗原特异性,细胞黏附试验检测其中和活性。结果筛选出1株可稳定分泌抗人ICAM-1抗体的杂交瘤细胞株3F2,杂交瘤染色体众数为98~104。纯化后的单抗蛋白浓度为1.253 mg/ml,纯度达83.6%,效价可达2.56×105。其分泌的抗体亚型为IgG1,腹水效价达5.12×105,可与ICAM-1特异性结合,可抑制ICAM-1与淋巴瘤细胞间的黏附,具有明显的中和ICAM-1的活性。结论已成功制备出抗ICAM-1的McAb,为其进一步的研究和应用奠定了基础。     

重组人B7-H4IgV融合蛋白的表达、纯化及活性

目的表达、纯化重组人B7-H4IgV融合蛋白,并检测其活性。方法将人B7-H4胞外片段IgV区基因插入pQE-30原核表达载体,转化大肠杆菌,IPTG诱导表达。表达产物经Ni2+-NTA柱亲和层析纯化,并进行Westernblot鉴定。用纯化的rhB7-H4IgV蛋白免疫昆明小鼠,经ELISA、流式细胞术测定小鼠抗血清的活性;免疫SP2/0荷瘤小鼠,观察对肿瘤细胞生长的抑制作用。结果表达的rhB7-H4IgV蛋白约占菌体总蛋白的25%,纯化后蛋白纯度为93%,浓度约为0.5mg/ml,与抗His单抗可产生特异性反应条带。免疫昆明小鼠产生的抗血清效价可达1∶10000,可与SP2/0肿瘤细胞结合。rhB7-H4IgV蛋白对SP2/0移植瘤生长具有一定的抑制作用。结论已成功表达并纯化了重组人B7-H4IgV融合蛋白,纯化蛋白可诱发小鼠体内免疫应答,产生的抗体能与表达B7-H4的肿瘤细胞SP2/0结合,rhB7-H4IgV蛋白在一定程度上能抑制SP2/0移植瘤的生长。