纳豆芽孢杆菌菌剂的制备工艺

采用单因素及正交试验对纳豆芽孢杆菌发酵培养基、pH、温度、发酵时间等条件进行了考察,利用喷雾干燥法制备菌剂,考察了β-环糊精、蔗糖、可溶性淀粉及脱脂奶粉作为保护剂对菌剂制备的影响,并研究了储藏时间及条件对菌剂发酵活力的影响.研究结果表明:纳豆芽孢杆菌发酵培养基为黄豆浸汁培养基:黄豆以5倍水体积浸泡8~14h,121℃~126℃,0.1~0.15MPa处理1h,滤除黄豆,取豆水,加入5%的葡萄糖和0.02%的K2HPO4,调节pH至7.0;最优发酵工艺:初始pH7.0,37℃发酵10h;喷雾干燥最佳保护剂为5%脱脂奶粉;菌剂4℃冷藏180d以内不影响发酵活力.上述工艺下所制得的纳豆芽孢杆菌菌剂活菌数为6.5×108 CFU/g,发酵生产纳豆激酶性能良好.发酵生产纳豆激酶酶活为2 000~2 200IU/g.本研究为纳豆芽孢杆菌菌剂制备提供了一条较为合理的工艺路线.     

异丁烯残留量对丁基橡胶溴化的影响

溶液法制备丁基橡胶可以直接得到丁基橡胶胶液,为溴化节省工艺步骤。但由于丁基橡胶优异的气密性,使得胶液中未反应的异丁烯单体很难彻底脱除。采用顶空气相色谱建立了测定胶液中异丁烯质量浓度的方法,将含有不同质量浓度异丁烯的胶液溴化,探究了异丁烯残留量对丁基橡胶溴化的影响。结果表明,随着胶液中异丁烯质量浓度的增加,溴化丁基橡胶的含溴质量分数不断降低,且溴代仲位烯丙基结构与溴代伯位烯丙基结构的相对摩尔比值逐渐增大。     

天然气管道氮气隔离混气长度研究

基于一维混合模型研究天然气管道投产过程中气体的混合规律,利用Taylor、Taylor-CW、G.R.I 3种不同方法分别计算出气体扩散系数及投产过程中形成的天然气-氮气混气段长度,分析了管道置换过程中影响混气长度的主要因素,包括管长、管径及流速。由Taylor-CW方法计算出的结果与现场数据最为接近,用该方法验证国内3条已投产管道所得的相对误差分别为39.7%、23.4%、22.0%。     

宁德山区旅游业发展对策研究

宁德山区有着丰富的旅游资源和垄断性的生态环境,发展旅游对于促进山区的经济发展有着重要的意义。本文在分析山区旅游发展现状和存在问题的基础上,提出一些发展对策,以期对各地山区旅游发展有一定借鉴意义。     

复合地基上加筋土挡墙力学响应及影响因素分析

为了明确复合地基上加筋土挡墙力学行为,利用非线性分析软件ADINA建立有限元模型,建立了复合地基上的加筋土挡墙力学响应分析模型,将路面荷载与行车荷载共同等效为均布荷载。分析结果表明:复合地基上加筋土挡墙在施工期间的沉降量存在一个临界值,当填筑至某一层位后总沉降量显著下降;每一层加筋土层都会发生不均匀沉降,最上面一层最明显;水平变形最大值发生在面板中下部,随着时间的推移,墙体的变形越来越稳定,稳定后其水平变形形成鼓肚形状。对影响复合地基上加筋土挡墙竖向变形的参数如加筋间距、填土性质、地基刚度等进行了分析。结果表明,在格栅选择、面板设计、地基刚度控制、垫层模量及厚度设计等方面的合理设计可以有效减少挡墙竖向变形;同时还能减少路面的不均匀沉降。该研究对复合地基上加筋土挡墙设计与施工具有重要指导意义。     

基于乡村旅游视角的湖北省农产品营销实证研究

以乡村旅游为平台进行农产品营销,有助于降低农产品的成本,增加农产品的附加值,带动农村相关产业的发展和进一步调整农村的产业结构,寻求“三农”问题的解决的新途径。本文通过对湖北省乡村旅游中农产品营销开展问卷调查所收集的数据进行统计分析,并对统计结果进行描述和分析,找出了其中存在的一些问题,提出了适合在乡村旅游背景下销售农产品的创新策略。     

多种测井曲线校正方法在塔中顺9井区的应用

针对顺9井区柯坪塔格组声波时差和密度曲线失真严重的问题。首先建立了工区的区域岩石物理模板判断测井曲线的失真段,然后使用了经验公式法、多元线性拟合法和岩石物理建模法对声波时差和密度曲线进行了校正。对比发现,经验公式法和多元线性拟合法适用于井眼垮塌较小的井段,而岩石物理建模更适用于井眼垮塌较严重的井段。最后利用区域岩石物理模板和合成地震记录标定约束并检验了曲线校正的结果。结果表明这三种曲线校正方法在顺9井区的应用是有效的、可行的。     

Defect formation and its effect on the thermodynamic properties of Pu2Zr2O7 pyrochlore: a first-principles study

In the past decades, pyrochlores, such as Gd₂Zr₂O₇, have demonstrated great potential to immobilize nuclear wastes such as Pu, which results in the production of Pu₂Zr₂O₇. Due to the high radioactivity of Pu, it is difficult to investigate the radiation response behavior of Pu₂Zr₂O₇ and its physical properties of the damaged state experimentally. Consequently, few related data have been reported in the literature thus far. In this study, first-principles calculations have been carried out to investigate the defect formation and its effect on the thermodynamic properties of Pu₂Zr₂O₇. It reveals that Pu_Zr antisite and O_8a interstitial defects are very easy to form in Pu₂Zr₂O₇. In particular, the O_8a interstitial defect can be formed spontaneously, while it is mechanically unstable. When vacancy, interstitial or antisite defects are formed in Pu₂Zr₂O₇, and the elastic moduli and Debye temperature are decreased. Besides, better ductility is resulted. As compared with other zirconate pyrochlores, such as Gd₂Zr₂O₇, the Pu₂Zr₂O₇ is suggested to be less resistant to radiation-induced amorphization. This study demonstrates that the created defects due to self-radiation from actinide decay have remarkable influences on the thermophysical properties of Pu₂Zr₂O₇.     

Ultrahigh molecular weight polyethylene with improved crosslink density,oxidation stability,and microbial inhibition by chemical crosslinking and tea polyphenols for total joint replacements

Highly crosslinked ultrahigh molecular weight polyethylene (UHMWPE) stabilized by vitamin E (VE) is widely applied in artificial joints as the bearings. Despite the approval, there is a discord that VE lowers the crosslinking efficiency, limiting its use at high concentration. In this work, we aim to obtain highly crosslinked and oxidation resistant UHMWPE through the conjunction of tea polyphenol and chemical crosslinking. We hypothesized that highly incorporated tea polyphenol with multiple reactive sites can ameliorate crosslinking efficiency of chemical crosslinked UHMWPE in comparison to VE. Epigallocatechin gallate (EGCG) as representative tea polyphenol was incorporated into UHMWPE at high concentration (2–8 wt%), followed by chemical crosslinking with 2 wt% organic peroxide. Unlike VE/UHMWPE blends as the control, chemical crosslinking achieved an increasing trend in crosslink density of EGCG/UHMWPE blends with increasing antioxidant concentration. High concentration of EGCG also enhanced the oxidation stability of UHMWPE. Intriguingly, EGCG endowed UHMWPE with an excellent antimicrobial property, which was inefficient in VE/UHMWPE. Cell viability was hardly affected by the high loaded antioxidant and peroxide. The chemically crosslinked UHMWPE blended with EGCG is proved to be a reasonable, cost effective and realistic alternative for use in artificial joints.     

聚酯型聚氨酯乳液的合成及性能

以异佛尔酮二异氰酸酯（ IPDI）、六亚甲基二异氰酸酯（HDI）和聚己二酸 1,4-丁二醇酯二醇（ PBA）为主要原料制备系列水性聚氨酯乳液（ WPU）。采用红外光谱仪、差式扫描量热仪、 X-射线衍射仪、电子拉力机等对 WPU进行结构表征;为了从聚集状态上对聚氨酯结晶性有更深层次的探究,对 WPU进行了定伸情况下的测试。结果显示：随着硬段含量的增加,硬段 -软段间的氢键相互作用减小,微相分离程度增加,结晶性能降低;随着伸长率的增加,氢键相互作用和结晶性能都表现出先减小后增大的趋势。当硬段含量为 14. 73%时,聚氨酯胶膜拉伸强度达到 40. 11 MPa,剥离强度为 93. 7 N/（25 mm）。