水热法合成(K,Na)NbO_3陶瓷粉体及其压电性能研究

利用水热法在碱性溶液中合成了具有钙钛矿结构的(K,Na)NbO_3无铅压电陶瓷粉体,研究了初始溶液中K+的含量对产物晶相、形貌以及化学组成的影响。采用X射线衍射仪以及扫描电镜对产物的结构和形貌进行了表征,利用X荧光分析仪对粉体的化学组成进行了精确分析。实验结果表明:随着初始溶液中K~+含量的变化,有两相钙钛矿(K,Na)NbO_3粉体生成,在溶液中K~+的反应活性低于Na~+。然后,将水热合成的K_(0.58)Na_(0.42)NbO_3粉体采用传统固相烧结制备陶瓷材料,其结构较致密,压电常数d_(33)达到94 pC/N。     

微波辅助提取龙葵浆果中花青素工艺研究

以野生龙葵浆果为原料,优化其花青素的最佳微波提取工艺:盐酸水溶液与物料的最佳液固比为17.5∶1,盐酸浓度为0.75%,微波辐射功率为700 W,提取温度为70℃,提取时间为6 min;并用pH值示差法测定龙葵浆果中花青素含量为1.806±0.016 mg/g。     

微生物学课程教学中的几点思考

微生物学是一门重要的基础课程,本文概述了在教学中存在的主要问题,并从以下几个方面入手探索了提高教学效果的方法:建立良好师生关系;利用多媒体教学、对比式教学和案例式教学优化教学内容,提高学生学习兴趣;改革考核模式,强化过程考核,提高学生学习自主性。     

寡肽制备技术及其在日化领域的研究进展

寡肽具有重要的营养和生物学功能,是重要的日化功能性原料。结合近年来在寡肽制备方法及其在日化领域的应用进展进行了系统综述。     

Textural,Rheological and Sensory Properties and Oxidative Stability of Nut Spreads—A Review

Tree nuts are rich in macro and micronutrients, phytochemicals, tocopherols and phenolic compounds. The development of nut spreads would potentially increase the food uses of nuts and introduce consumers with a healthier, non-animal breakfast snack food. Nut spreads are spreadable products made from nuts that are ground into paste. Roasting and milling (particle size reduction) are two important stages for the production of nut spreads that affected the textural, rheological characteristic and overall quality of the nut spread. Textural, color, and flavor properties of nut spreads play a major role in consumer appeal, buying decisions and eventual consumption. Stability of nut spreads is influenced by its particle size. Proper combination of ingredients (nut paste, sweetener, vegetable oil and protein sources) is also required to ensure a stable nut spread product is produced. Most of the nut spreads behaved like a non-Newtonian pseudo-plastic fluid under yield stress which help the producers how to start pumping and stirring of the nut spreads. Similar to other high oil content products, nut spreads are susceptible to autoxidation. Their oxidation can be controlled by application of antioxidants, using processing techniques that minimize tocopherol and other natural antioxidant losses.     

塔里木盆地巴麦地区小海子组成岩作用研究

通过岩心观察、铸体薄片以及阴极发光等手段对巴麦地区小海子组的岩石类型及成岩作用做了充分研究。结果表明:小海子组发育的岩石类型中,残余粒屑灰质白云岩和粉晶白云岩的物性较石灰岩要好;成岩作用对储层物性的影响较大,其中建设性的成岩作用有白云石化、溶蚀和破裂作用,破坏性的成岩作用有泥晶化、压实和胶结充填作用,影响不明显的成岩作用有重结晶和压溶作用。此研究对小海子组储层的成岩作用有参考意义,也可为后期勘探提供依据。     

Physical study of room‐temperature‐cured epoxy/thermally reduced graphene oxides with various contents of oxygen‐containing groups

In this study, the effects of different oxygen‐containing group contents in thermally reduced graphene oxides (TRGs) for enhancing the physical properties of epoxy nancomposites was examined. The epoxy/TRG nanocomposites (ETNs) were prepared by a room temperature curing method in the presence of TRGs containing different oxygen‐containing groups and were then characterized by Fourier transform infrared spectroscopy. TRG contents with higher oxygen‐containing group contents (ca 33%) were found to show better dispersion capability in the epoxy matrix than TRGs with lower oxygen‐containing group contents (ca 11%) based on morphological observations by transmission electron microscopy. The better dispersion capability of TRGs with higher oxygen‐containing group contents in ETN membranes was found to lead to significantly enhanced mechanical strength, thermal stability and thermal conductivity based on measurements of dynamic mechanical analysis, tensile tests, thermogravimetric analysis and by the transient plane source technique. © 2014 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry     

抗菌肽Cecropin D在毕赤酵母中的表达、纯化及活性鉴定

目的在毕赤酵母GS115中表达抗菌肽Cecropin D,并检测其抗菌活性。方法根据毕赤酵母密码子的偏爱性,人工合成6条寡聚核苷酸片段,经磷酸化、退火、连接并克隆入酵母表达载体pPIC9K。重组表达质粒pPIC9K-D转化至毕赤酵母菌GS115,经G418筛选,阳性高拷贝克隆用0.5%的甲醇诱导表达,表达产物经CM-Sepharose层析柱纯化,Tricine-SDS-PAGE分析,琼脂糖扩散法和比浊法测定其抗菌活性。结果经Tricine-SDS-PAGE检测,在相对分子质量3900左右处可见目的蛋白表达条带,纯化后的目的蛋白纯度达90%以上,获得的抗菌肽Cecropin D对一些革兰阳性菌和革兰阴性菌均有抑菌活性。结论抗菌肽Cecropin D成功地在毕赤酵母中分泌表达,为以后深入研究抗菌肽奠定了基础。     

基于BP网络模型的水合肼合成收率预测及参数优杞

采用BP算法建立了水合肼合成收率的神经网络模型，所建网络有良好的回想和泛化性能，对水合肼合成收率预测的平均相对误差小于0．5％。运用网络模型考察了反应温度、物料配比、次氯酸钠流量等操作参数对水合肼合成收率的影响，同时确定了获得较高合成收率时各操作参数的优化值。     

Modeling of a metal monolith catalytic reactor for methane steam reforming-combustion coupling

A novel metal monolith reactor for coupling methane steam reforming with catalytic combustion is proposed in this work, the metal monolith is used as a co-current heat exchanger and the catalysts are deposited on channel walls of the monolith. The transport and reaction performances of the reactor are numerically studied utilizing heterogeneous model based on the whole reactor. The influence of the operating conditions like feed gas velocity, temperature and composition are predicted to be significant and they must be carefully adjusted in order to avoid hot spots or insufficient methane conversion. To improve reactor performance, several different channel arrangements and catalyst distribution modes in the monolith are designed and simulated. It is demonstrated that reasonable reactor configuration, structure parameters and catalyst distribution can considerably enhance heat transfer and increase the methane conversion, resulting in a compact and intensified unit.