真空冷冻干燥机冷阱中的气体换热分析

从理论上分析了螺旋盘管式冻干机冷阱中气体的换热。对真空冷阱中处于滑流区的气体换热 ,应考虑温度跳跃和速度滑移对换热的影响。基于冷阱内表面定热流和恒壁温的假设 ,建立了相应的分析模型 ,导出了冻干机冷阱内处于滑流区的气体换热 Nusselt数表达式 ,认为随着冷阱压力的降低 ,换热 Nusselt数将不断减小     

Overview of cold regions mobility modeling at CRREL

Over the last several decades, the Cold Regions Research and Engineering Laboratory (CRREL) has extensively tested and analyzed issues related to vehicle performance in winter. Using this knowledge and the experimental database, models were developed to capture the important elements for cold regions mobility performance. These models span a range of resolutions and fidelities and include three-dimensional finite element models of tire–terrain interaction, vehicle dynamics models of vehicles on winter surfaces, semi-empirical cold regions algorithms for winter performance within the NATO reference mobility model (NRMM), all-season vehicle performance in force-on-force war-gaming simulations, and vehicle–surface interaction for real-time vehicle simulators. Each of these types of models is presented along with examples of their application.     

Modeling of vacuum desorption of multicomponent moisture in freeze drying

A mathematical model of multicomponent vacuum desorption, which occurs in the vacuum freeze drying process has been developed. Drying with conductive heating and constant contact surface temperature was considered. Pressure drop in the layer of the material to be dried was taken into account in the model formulation and process simulation. Equilibrium moisture content for pure water, toluene, and m-xylene and their two- and three-component mixtures on zeolite DAY 20F were described by means of the multitemperature extended Langmuir isotherm equation. Model equations were solved by the numerical method of lines. Moisture content and temperature distributions within the drying material were predicted from the model as a function of drying time.     

低密度聚乙烯/聚丙烯聚乙烯共聚物共混体系混溶性的研究

通过在溶液中混和，然后采用将溶液冷冻干燥的方法，获得低密度聚乙烯与聚丙烯聚乙烯共聚物的共混物，用ＤＳＣ及洗提技术对其进行了表征，讨论了配比及淬火条件对此共混体系混溶性的影响，证明了通过冷冻干燥的方法可显著提高共混体系的混溶性．     

冻融法提取猪血纤维蛋白原

利用纤维蛋白原在低温下可形成絮状沉淀的性质,以样品中纤维蛋白原含量及提取率为考查指标,采用冻融法从猪血中提取纤维蛋白原.确定提取条件为:将抗凝血浆在-20 ℃温度下冷冻12 h,经4 ℃解冻,低温离心收集纤维蛋白原样品.样品中纤维蛋白原含量达82.6%,提取率达91.0%,符合静脉注射纤维蛋白原要求.     

低温冰箱冷冻对人体组织拉曼光谱的影响

研究了低温冰箱冷冻保存时间对人体甲状腺组织、子宫肌瘤组织的拉曼光谱的影响。组织用磷酸缓冲生理液浸泡 ,于 - 4℃保存 (未冻 ) 1 0 h,测试拉曼光谱 ;测后将组织样品浸入磷酸缓冲生理液 ,置于低温冰箱 - 30℃保存。分别于冷冻几天、十几天和六十天后 ,取出解冻测试拉曼光谱。结果表明 ,冷冻保存 1 0天内对组织的拉曼光谱没有明显的影响。该结果对拉曼光谱研究人体组织具有指导意义     

海刺参及其产品红外光谱的分析与鉴定

作为高档的保健品,深加工的海刺参产品如海刺参注射液、海刺参胶囊等,有着广阔的市场前景,但是目前还没有统一有效的品质鉴定手段和标准。作者采用傅里叶变换红外光谱法(FTIR)和二维相关红外光谱技术(2DIR)对海刺参粉末进行分析,得到了自制海刺参粉的谱图,然后以此为标准对五个不同厂家的海刺参胶囊进行相关性比较,结果显示大连海晏堂的海刺参胶囊与作者自制的鲜活冻干样品最为相符,这表明它基本上是纯的冷冻干燥海刺参粉;实验还表明通过建立标准红外谱图库来监控海刺参产品质量、制定统一标准是完全可能的。     

冷冻升华制备的超高分子量聚乙烯寡链、多链晶体的凝聚态

在10^-3～10^-5g/mL浓度范围内,用冷冻升华法制备了超高分子量聚乙烯(UHPE)单链、寡链、多链的折叠链晶聚集体.长达几万纳米的UHPE分子链可以以不同的片晶参与结晶,或自身形成数个晶粒,即形成单链多晶.DSC研究结果表明,随着溶液浓度的降低,冷冻升华样品的熔点和结晶度均降低.由熔点估算了晶粒的体积和晶粒中包含的链数,它们亦随溶液浓度降低而降低.冷冻升华得到的小晶粒中链的缠结少,晶体具有较高的完善性.用WAXD测试晶粒的(110)和(200)面的法向尺寸,由此计算晶粒的平均体积,与熔点计算得到的数值一致.     

Processing micrometer-sized particles in crumpled graphene network for freestanding membrane enabled by freeze casting

Graphene oxide(GO)is widely used in the construction and application of various 2 D membrane-based materials due to its unique colloidal structure.Herein,we demonstrate that micrometer-sized particles can make up freestanding membranes enabled by the extraordinary amphiphilic and polymer-like properties of graphene oxide through freeze casting.The 2 D macromolecule,GO could well wrap the particles for better uniformity and stability in either dispersion or membrane.Importantly,freeze casting plays an important role in avoiding the severe aggregation of micrometer-sized particles in the solventremoving process.After reduction,the membrane exhibits good electrical conductivity while maintaining its integral structure,which can be directly used as a freestanding binder-free electrode.This work provides a universal approach to fabricate freestanding membranes with various micrometersized materials for energy storage.     

低密度聚乙烯/聚丙烯 聚乙烯共聚物共混体系混溶性的研究

通过在溶液中混和，然后采用将溶液冷冻干燥的方法，获得低密度聚乙烯与聚丙烯 聚乙烯共聚物的共混物，用ＤＳＣ及洗提技术对其进行了表征，讨论了配比及淬火条件对此共混体系混溶性的影响，证明了通过冷冻干燥的方法可显著提高共混体系的混溶性．