用盐桥支撑双分子层脂膜模拟研究锌离子跨细胞膜输运

采用盐桥支撑技术制备镶嵌胆固醇的双分子层卵磷脂(脑磷脂)膜,对膜配方、双分子层脂膜的稳定性、离子通透性、双层膜中胆固醇对离子通透性的影响等进行了研究,得到了最佳制膜工艺,并利用实验制备的双分子层脂膜模拟研究锌离子跨细胞膜的输运过程,建立了锌离子跨细胞膜的吸附．扩散模型,其计算值与实验值基本吻合。     

生化反应──色谱分离耦合过程模型研究

建立了描述生化反应─色谱分离耦合过程的一般数学模型,以蔗糖酶促水解制果糖、葡萄糖为模型反应,研究了底物转化率和产物分离度与操作条件的关系.理论计算值与实验结果在低浓度下符合较好．     

电解质(NaCl和KCl)及其混合物含水溶液在298.15K下的粘度

在298.15K下,测量了NaCl、KCl及其不同摩尔比下的混合物的水溶液的粘度及密度,浓度从很稀直至饱和、甚至过饱和．通过在现有的扩展Jones─Dole型方程中加入摩尔浓度的立方项,所得Jones─Dole型方程可在更高浓度范围内很好地表达所研究体系的粘度．随着浓度的提高,更高浓度次项需加入．用简单加和规则计算了混合物溶液的粘度,其结果与实验值在低浓度下相近,可解释为,有足够的水用来水化离子,离子间的作用对粘度几乎无影响;随着浓度的增加,计算值比实验值越来越小,因为离子间的作用越来越明显,并且各自的浓度由于彼此的存在和作用而提高．     

含叔丁醇体系的汽液平衡测定和关联

测定了正己烷─叔丁醇，正庚烷─叔丁醇体系的常压汽液平衡数据。采用马丁─侯状态方程、Ｗｉｌｓｏｎ、ＮＲＴＬ活度系数模型关联了实验数据，计算值与实验值吻合较好。     

4─氨基安替比林萃取比色法测定挥发性酚空白值的探讨

介绍了4─氨基安替比林萃取比色法测定挥发性酚过程中影响空白值的主要因素,并对消除影响的方法进行了探讨。     

钛合金镀铜、镀银工艺

为克服钛合金氰化镀铜、镀银层结合力不良的问题,通过改变基体预处理方式设计了5个镀铜、镀银方案并进行结合力表征,得到钛合金镀铜、镀银的最佳工艺流程为:湿吹砂─保护─轻石灰刷洗除油─冷水洗─酸性镀铜或氰化镀银─冷水洗─压缩空气吹干。生产实践证明采用该工艺电镀所得产品结合力均合格,且含氢量不超标。介绍了电镀过程中控制钛合金含氢量的方法和注意事项。     

2─巯基嘧啶衍生物对硫酸溶液中碳钢和低合金钢的缓蚀作用

９４─０３３２─巯基嘧啶衍生物对硫酸溶液中碳钢和低合金钢的缓蚀作用对几种２─巯基嘧啶衍生物作为１Ｍ硫酸中Ａｒｍｃｏ钢和低合金钢的缓蚀剂进行了实验。实验在６０～９０℃下进行６ｈ。通过极化电阻测定和溶解铁的分析测定，腐速的趋向是时间的函数。２─巯基嘧啶、...     

气泡聚并机理模型

对气液二相体系中气泡间凸面状薄液膜内以及气液界面上动量和质量传递行为进行了分析,建立了气泡聚并时间模型,考虑了范德华作用力以及双电层作用力对液膜变薄过程产生的影响.模型值与文献实验值吻合较好.     

多孔材料热风干燥过程中力学特性分析

为了得到高品质的干制品,基于黏弹性理论和Maxwell固体特性,建立了多孔材料干燥过程中黏弹性应力数学模型。采用MATLAB编程的方法对马铃薯热风干燥过程中内部各单元层干燥应力进行数值模拟计算。计算结果表明:随着干燥过程的进行马铃薯各单元层产生干燥应力为压应力且逐渐增大,达到最大值后开始减小;当压应力减小到0时出现应力反向现象,各单元层应力由压应力变成拉应力,拉应力逐渐增大到最大值后开始减小直至达到平衡不再发生变化。在整个热风干燥过程中干燥过程中,内单元层干燥应力值总是大于外单元层应力值,且表单元层的干燥应力始终为0。通过实验对模型进行验证,验证结果表明此模型可以用来表述干燥过程中多孔材料内部应力变化和分布规律。     

2─噁唑啉化合物改性PET的结晶动力学研究

用ＤＳＣ法研究了双─２─唑啉基苯改性ＰＲＴ的结晶动力学．采用等温和非等漫结晶两种动力学研究方法，获得对ＰＥＴ改性前后结品行为和动力学参数差别的实验数据，为此助剂推广应用提供了依据．     

草菇,菠萝的冷冻干燥过程及影响因素分析

从草菇、菠萝做冷冻干燥试验所得的冻干曲线和冻干时间,用分子运动论的观点分析了温度、压力等因素对冷干燥过程的影响。     

变温冷冻干燥升华时间的估算

本文建立了变温冷冻干燥升华过程的拟稳态理论模型，并对草菇冻干过程中升华阶段的升华温度、升华界面移动速率及升华时间进行了计算。实验证明，计算值与实验结果吻合较好。     

The Effect of Glass Transition Temperature on the Procedure of Microwave–Freeze Drying of Mushrooms (Agaricus bisporus)

Freeze drying (FD) yields the best quality of dried mushroom but at the cost of a long drying time and high overall cost. Air drying (AD) gives an unacceptably poor quality product. To achieve faster drying along with a high-quality product, a microwave–freeze drying (MFD) technique was developed to dry mushrooms. The relationship between dried mushroom quality and the glass transition temperature during the MFD process was studied to optimize the MFD process. According to the change tendency of the glass transition temperature of mushroom during MFD, a step-down microwave loading scheme for the MFD process was developed to obtain good product quality.     

Drying of shiitake mushroom by combining freeze-drying and mid-infrared radiation

Mid-infrared drying (MIRD) was applied before or after freeze-drying (FD) of shiitake mushroom to shorten the drying time, to enhance the rehydration, and to better preserve the aroma compounds and color. The effect of application of MIRD before freeze drying (MIRD–FD) and after freeze drying (FD–MIRD) on drying time, color, rehydration ratio, apparent density, microstructure and aroma compounds was measured, explained and compared with the effect of FD on these parameters. The results showed that the combination of FD (for 4 h) followed by MIRD saves 48% time compared to FD while keeping the product quality at an acceptable level. The MIRD–FD combination was found to be inferior compared to the FD–MIRD as the former tended to produce products with a collapsed surface layer and poor rehydration capability. The combination of MIRD with FD had a significant effect on aroma retention and caused an increase of sulfur compounds such as dimethyl, trisulfide and 1,2,4-trithiolane.     

Optimization of microwave freeze drying strategy of mushrooms (Agaricus bisporus) based on porosity change behavior

ABSTRACT

For dehydrated foods, porosity is a crucial parameter which affects mass and heat transfers, and is related to the product quality. It is important to monitor porosity change behavior to optimize the drying process. To achieve faster drying along with high product quality, microwave freeze drying (MFD) was applied to mushrooms dehydration processing. The relationship between porosity (include total, open-, and closed-pore porosity) and dried mushroom qualities was studied, and a suitable microwave loading strategy was obtained. It was found that lots of open pores could transform to closed pores while the moisture content (MC) was below 0.25?±?0.05?g/g (db), and the closed-pore porosity was arrived at a relatively stable level at moisture content below 0.17?±?0.03?g/g (db). Both total porosity and closed-pore porosity had a significant influence (P?<?0.01) on texture of MFD mushroom, and open-pore porosity had a significant effect (P?<?0.01) on rehydration ratio of MFD mushroom. According to the porosity change behavior of mushrooms, a dynamic microwave loading strategy can be used to reduce drying time and keep product quality during MFD process.     

常压吸附流化冷冻干燥技术的研究与探索

阐述了常压吸咐流化冷冻干燥与真空冷冻干燥的原理，特点，研究概况和能耗分析，提出常压吸附流化冷冻干燥可能成为一种新型冷冻干燥技术而具有较高的研究开发价值。     

Optimal Control of the Secondary Drying Stage of Freeze Drying of Solutions in Vials Using Variational Calculus

Abstract:

The problem of operating freeze drying of pharmaceutical products in vials loaded on trays of freeze dryer to obtain a desired final bound water content in minimum time is formulated as an optimal control problem. Two different types of freeze dryer designs were considered. In the type I freeze dryer design, upper and lower plate temperatures were controlled together, while in the type II freeze dryer design, upper and lower plate temperatures were controlled independently. The heat input to the material being dried and the drying chamber pressure were considered as control variables. Only the scorch temperature was considered as a constraint on the system state variables during the secondary drying stage, because all the free water content (frozen water) is removed from the solid matrix during the primary drying stage of freeze drying. Necessary conditions of optimality for the secondary drying stage of freeze drying process in vials were derived and presented by using rigorous multidimensional unsteady-state mathematical models. The theoretical approach presented in this work was applied in the freeze drying of skim milk. Significant reductions in drying times of the secondary drying stage of the freeze drying process in vials were observed and more uniform bound water and temperature distributions in the material being dried were obtained compared to the conventional operational policies.     

Optimal Control of the Primary Drying Stage of Freeze Drying of Solutions in Vials Using Variational Calculus

The problem of operating freeze drying of pharmaceutical products in vials placed in trays of a freeze dryer to remove free water (in frozen state) at a minimum time was formulated as an optimal control problem. Two different types of freeze dryer designs were considered. In type I freeze dryer design, upper and lower plate temperatures were controlled together, while in type II freeze dryer design, upper and lower plate temperatures were controlled independently. The heat input to the material being dried and the drying chamber pressure were considered as control variables. Constraints were placed on the system state variables by the melting and scorch temperatures during primary drying stage. Necessary conditions of optimality for the primary drying stage of freeze drying process in vials are derived and presented. Furthermore, an approach for constructing the optimal control policies that would minimize the drying time for the primary drying stage was given. In order to analyze optimal control policy for the primary drying stage of the freeze-drying process in vials, a rigorous multi-dimensional unsteady state mathematical model was used. The theoretical approach presented in this work was applied in the freeze drying of skim milk. Significant reductions in the drying times of primary drying stage of freeze drying process in vials were obtained, as compared to the drying times obtained from conventional operational policies.     

Foam-Mat Freeze Drying of Egg White—Mathematical Modeling Part II: Freeze Drying and Modeling

Foam-mat freeze drying is one of the promising methods of drying, which utilizes advantages of both freeze drying and foam-mat drying. Egg white with its excellent foaming properties makes a suitable candidate for foam-mat freeze drying. Experiments were conducted to study foam-mat freeze drying of egg white, in an effort to determine the suitability of this method. Xanthan gum (XG) at 0.125% concentration was used as stabilizer for foaming. The results showed that the addition of xanthan gum during foaming has a positive impact in reducing the total drying time and also produces excellent quality egg white powder. The addition of stabilizer also plays an important role in improving drying. Simple models were applied for determining drying time and diffusion coefficients during freeze drying.     

瓶装物料的冻干规律研究

以脱脂牛奶为物料,进行了瓶装物料的冷冻干燥试验,探索了加热温度,辐射温度与冻干室压强对冻干过程的影响规律,分析了所得冻干曲线的特征,并对冻干机理和物料温度的监测井行阐述,得到在加热温度与辐射温度相同时恒温恒压操作的最佳参数,并提出了一些强经冻干过程的措施。本研究对实验冻干生产有一定的指导作用,也为瓶装物料的二维理论模型研究提供了基础。