酵母乳糖酶对牛乳乳糖水解作用的研究

采用乳酸克鲁维酵母的乳糖酶(β-乳糖苷酶)对乳糖溶液、喷雾干燥脱脂奶以及全脂奶进行了试验,以确定将乳糖转化成单糖的最适条件。当牛奶中酶浓度为3u/ml时,于40℃反应2小时或4℃反应24小时,约60％的乳糖得以水解。随着乳糖浓度的增高,水解程度也有所提高。当酶浓度为10U/ml时,于40℃反应2小时,90％乳糖得以水解。用自制的乳酸克鲁维酵母的乳糖酶和加拿大lactaid Inc.生产的乳糖酶制剂lactaid水解乳糖无大的差异。     

Phase stability and thermo-physical properties of ZrO2-CeO2-TiO2 ceramics for thermal barrier coatings

The properties of ZrO₂ co-stabilized by CeO₂ and TiO₂ ceramic bulks were investigated for potential thermal barrier coating (TBC) applications. Results showed that the (Ce_0.15Ti_x)Zr_0.85-xO7 (x?=?0.05, 0.10, 0.15) compositions with single tetragonal phase were more stable than the traditional 8YSZ at 1573?K. These compositions also showed a large thermal expansion coefficient (TEC) and a high fracture toughness, which were comparable to those of YSZ. However, the phase stability, fracture toughness and sintering resistance of the CeO₂-TiO₂-ZrO₂ system showed a decline tendency with the increase of TiO₂ content. The TEC of the ceramic bulks decreased with increase of TiO₂ content as well because the crystal energy was enhanced with increasing substitution of Zr⁴⁺ by smaller Ti⁴⁺. The (Ce_0.15Ti_0.05)Zr_0.8O₂ had the best comprehensive properties among the (Ce_0.15Ti_x)Zr_0.85-xO₂ compositions as well as a low thermal conductivity. Therefore, it can be explored as a TBC candidate material for high-temperature applications.     

豆乳的乳酸菌发酵初探

利用乳酸菌发酵豆乳,结果表明,如同牛乳一样,豆乳也能提供乳酸菌生长所需的营养物质,并使豆乳的PH下降和产生凝乳现象。但经乳酸菌发酵的豆乳,其酸度远不如酸乳,而且乳酸菌的生长量也低于牛乳(前者仅10~7个/ml,后者达10~8个/ml以上)。添加葡萄糖、乳糖等物质于豆乳中,虽有助于提高豆乳的酸度,但效果不甚显著。此外,豆乳经乳酸菌发酵后也不能产生酸牛奶所具有的特殊香味或风味,也未检出双乙酰(丁二酮)和乙醛等物质。     

容迟容断传感器网络中基于节点活跃性的路由

容迟容断移动传感器网络DTMSN(delay/disruption tolerant mobile sensor network)用于广泛的数据收集,在DTMSN动态变化的网络环境中传统传感器网络的路由策略不再适用.提出了一种基于节点活跃性的路由策略ABR(activity-based routing),其出发点为:网...     

Failure of plasma sprayed nano-zirconia-based thermal barrier coatings exposed to molten CaO–MgO–Al2O3–SiO2 deposits

Recently, nanostructured thermal barrier coatings have received considerable attention because of some superior properties in comparison with their conventional counterpart. In this study, nanostructured 8 wt% yttria-stabilized zirconia (n-YSZ) coatings were deposited by atmospheric plasma spraying, and the degradation behavior caused by molten calcium-magnesium-aluminon-silicate (CMAS) attack was investigated. Results showed that the thermo-chemical reaction product between CMAS and YSZ (both powders and coatings) is different with the change of CMAS content. At low CMAS concentration, a cubic phase is generated by the diffusion of Ca into YSZ grains. As compared to the conventional YSZ, less C-ZrO₂ is detected for n-YSZ. When CMAS reaches a certain concentration (eg 15 mg/cm²), disruptive phase transformation from tetragonal to monoclinic will occur and the reaction is more readily for n-YSZ. Two different chemical reaction mechanisms governing the CMAS content effect were proposed. It should be noted that the nanozone in the coatings plays an important role in the CMAS degradation process, which enhances CMAS infiltration rate and accelerates the chemical reaction, leading to a poor CMAS resistance of the nanostructured coating than that of the conventional counterpart.     

一类三维混沌系统的Bautin分岔分析

研究一类具有三维自治常微分方程组形式的新的类Chen系统的余维二分岔．首先通过坐标变换，把原系统的平衡点平移到新系统的原点．通过对平移后所得新系统的Jacobi矩阵的分析，推导系统发生余维二Bautin分岔的参数条件．借助计算机对类Chen系统进行数值仿真，得到该系统发生Bautin分岔的分岔图，与理论推导结果相符合，从而验证了理论推导的正确性．     

国外节能服务产业发展特点及趋势

目前全球节能服务产业发展仍处于初级阶段,以中国、美国、欧洲和日本市场最为活跃。在梳理美国、欧洲和日本节能服务产业发展现状的基础上,研究这些国家节能服务产业发展的特点及趋势,总结其节能服务产业发展经验,为中国节能服务产业发展提供相关建议。     

中低压配电网节能改造方案经济效益评估

中低压配电网节能改造的节能潜力巨大,从更换电力设备、采用节能技术以及提升电能质量3个角度,分析并量化了中低压配电网4种节能改造方法的节能效益,建立各节能方法的全寿命周期成本模型,通过净现值、内部收益率及投资回收期对节能方案进行经济效益评估。最后对山东Q地区的实际算例进行计算,其经济效益评估指标均满足经济可行性,表明本文所建立的模型可为节能方案的经济效益评估提供参考。     

圆盘类精锻件顺序转向输送方法的研究及应用

针对圆盘类精锻件输送问题,提出了一种圆盘类精锻件顺序转向输送方法,对圆盘类精锻件多排变单排的输送形式及多排布局方案进行研究。输送过程分为两个阶段:第1阶段,第1输送装置进行多排输送;第2阶段,经自动落料装置按顺序依次落料至第2输送装置,实现了转向、单排输送。其中,第1输送装置的多排布局分别为由远及近、由近及远两种形式,第2输送装置的输送速度分别设置为ΔL/P、2ΔL/P、3ΔL/P、4ΔL/P,通过对以上8种组合的位置仿真分析得到了合理方案。研究及应用表明,若第2输送装置输送速度设置为4ΔL/P,则由近及远多排布局方案的布局形式满足了顺序转向的输送要求。