Foam‐Mat Freeze‐Drying of Bifidobacterium longum RO175: Viability and Refrigerated Storage Stability

Foaming as a pretreatment was used prior to freeze‐drying of Bifidobacterium longum RO175 to investigate the potential acceleration of the drying rate and increase in microorganism viability after the process. A study on storage of foamed and nonfoamed freeze‐dried products at 4 °C completed this study. B. longum RO175 in foamed medium could be freeze‐dried in 1/7 to 1/4 of the time required for nonfoamed suspensions. In addition, foamed suspensions presented higher viability immediately after freeze‐drying (13.6% compared to 12.81 % or 11.46%, depending on the cryoprotective media). Refrigerated storage led to a reduction in B. longum RO175 viability for all tested protective agents (foamed and nonfoamed). No correlation between glass transition temperature and stability of probiotic powders was observed during storage. In addition, lower viability after 56 d of storage was observed for foamed materials, probably due to foam porous structure and higher hygroscopicity, and oxygen presence and moisture pickup during storage.     

Impregnation of thermoplastic resin in jute fiber mat

Impregnation rate of thermoplastic resin (polypropylene) in jute fiber mat and influence of relative factors on impregnation were studied, aiming to develop the continuous melt impregnation technique and to investigate the effect of impregnation rate and temperature on processing conditions and mechanical properties of natural fiber mat-reinforced thermoplastics. Influence of pressure on porosity of fiber mat and effect of melt viscosity on impregnation rate were also investigated. The modified capillary rheometer was used as apparatus and experimental data were analyzed based on the one-dimension Darcy’s law. Results showed that at a given pressure, the impregnation rate is inversely proportional to melt viscosity and jute fiber mat has higher porosity than glass fiber mat. The architecture, compressibility, permeability and fiber diameter of jute fiber mat were compared with those of glass fiber mat and their effects on impregnation were discussed further. It could be seen that the average diameter of jute fiber is much bigger; the porosity of jute fiber mat is significantly higher and inner bundle impregnation does not exist in jute fiber mat. Therefore, it is not difficult to understand why the impregnation rate in jute fiber mat is 3.5 times higher and permeability is 14 times greater. Kozeny constants of jute and glass fiber mats calculated based on the capillary model are 2950 and 442, respectively. __________ Translated from Journal of Chemical Engineering of Chinese Universities, 2007, 21(4): 586–591 [译自: 高校化学工程学报]     

格宾石笼护坡技术在水库塌岸中的应用

主要通过边坡加固方案的选择、施工工艺及可能存在问题的分析,阐述了格宾石笼护坡技术在水库塌岸边坡中的应用,较好的加固了库区边坡,保证了新建道路的正常使用,达到了预期的目的。     

复合加筋格宾挡土墙施工技术

云南绥江县一中场平工程挡土墙采用新型加筋格宾挡土墙,通过挡土墙设计、坡面清除及基底施工、格宾材料及格宾网箱编织、格宾网箱填石、结构填土及土工织物施工,经检查验收和总体外观鉴定,该挡土墙墙面平顺美观、缝隙均匀、线形顺适,防水排水工程齐全,取弃土位置合理。     

湿纸幅成形过程中的阻力测定

通过对水以不同速度经过滤网时流动阻力的测定，确定了滤网阻力与流水速度之间的对应关系，利用这种关系，试验测定了一种白纸板的成形阻力。这种方法可用于纸浆滤水性和过滤特性的研究。 对试验数据的分析发现达西定律对薄页纸成形的适用性值得怀疑，对研究所用的试验设备也做了详细介绍。     

玻璃纤维轻质短切毡拉伸强力影响因素分析

分析了影响玻璃纤维轻质短切毡拉伸强力的各种因素,讨论生产过程中浸润剂与纤维的匹配性、粉末粘结剂的选择、单位面积质量均匀性控制、喷雾器流量控制等工艺因素变化对毡片拉伸强力的影响,通过对这些因素进行深入的分析和研究,提出了合理的解决方案。     

Optimization of Parameters for Microwave-Assisted Foam Mat Drying of Blackcurrant Pulp

Both analysis and optimization of parameters of microwave-assisted foam mat drying (MAFM), viz. microwave power, pulp load, drying time, and pulp thickness, for the dehydration process of blackcurrant pulp were performed in a household microwave oven. During MAFM drying, microwave power, pulp load, and drying time have positive effects on both vitamin C and anthocyanin content of blackcurrant pulp up to a certain level then a negative trend is observed. The increase of microwave power and decrease of pulp load accelerate the dehydration of blackcurrant pulp. The pulp thickness has a significant positive effect on both vitamin C and anthocyanin content of blackcurrant pulp. The optimum parameters valid for MAFM drying of blackcurrant pulp are as follows: microwave power of 560 W, pulp load of 65 g, drying time of 8 min, and pulp thickness of 4.46 mm. MAFM drying is a potential method for dehydrating blackcurrant pulp.     

新型玻纤毡用粉末粘结剂的研制

采用专门研制的PVAc树脂与中等数均分子量聚酯树脂混合制备得到新型的玻璃纤维原丝毡用粉末粘结剂。该粘结剂既保留了原有树脂的良好粘结力和理想的粒度分布,又有效地改善了贮存稳定性的问题,同时产品质量稳定性好。通过试验分析,选用的改性PVAc树脂要具有适合的软化点和较低的丙酮不溶物含量;聚酯树脂具有适合的软化点和分子量。进行两种树脂的不同配比试验,最后确定最适合的配方是GY-01-F。     

界面柔性层对玻璃纤维毡增强聚丙烯复合材料力学性能的影响

通过橡胶分子链在玻璃纤维表面的接枝,在玻璃纤维毡增强聚丙烯复合体系中引入了界面柔性层,研究了柔性层的种类及厚度对复合体系界面结合及力学性能的影响,结果表明,采用容易与玻璃纤维表面形成化学键等牢固结合与基体树脂有一定相容性的橡胶分子链作为界面柔性层,可以获得高强度,高抗冲的玻璃纤维毡增强聚丙烯复合材料,柔性层的厚度对复合体系的力学性能有很大的影响,超过一定的厚度后,随着柔性层的增厚,玻璃纤维增强聚丙烯复合材料的力学性能呈下降的趋势。     

GM T 熔融浸渍中熔体在玻纤毡中的流动

通过改装毛细管流变仪建立了专门的实验装置, 研究高温高压下熔体在纤维床层中的流动行为。采用一维恒压流动实验分别测量了不饱和及饱和流动状况下玻纤毡厚度方向聚丙烯熔体的渗透率, 考察了玻纤毡空隙率、单丝直径、针刺等几何结构对渗透率的影响。根据实验结果进一步讨论了GM T 片材熔融浸渍过程中的气泡形成以及浸渍工艺参数的选择。