进口导叶预旋对扩压器内部非定常流场影响的实验研究

本文在不同的进口导叶预旋下，采用热线风速仪对扩压器内的非定常流场进行了测量，采用锁相采样—集平均技术对热膜测量的瞬时信号进行处理，研究了进口导叶预旋角度和方向对扩压器内部非定常流场影响。结果表明，扩压器内部大部分紊流强度均有所增加；扩压器内的非定常性受导叶尾流及大尺度涡团的非定常影响而减小，且负预旋角度下非定常性的减小程度小于正预旋角度下的非定常性；扩压器内部的非定常流动的基本频率降低。     

激波/泄漏涡相互干扰对跨音压气机流动稳定性的影响

对单级跨音压气机Stage35进行了单通道全三维定常数值模拟,开展了网格密度对计算结果影响的研究,从而确定了一套最佳网格配置,该套网格配置预测的总性能和基元性能与试验结果符合得最好。以此为基础对Stage 35的内部流场进行分析,发现其流动失稳很可能是由动叶近叶顶靠近压力面侧的低能堵塞团引发的。随着流量的减小,间隙泄漏涡的强度和旋拧度随着叶片载荷的增加而增加,激波与泄漏涡相互干扰使得近失速条件下间隙泄漏涡破碎,涡破碎可能是动叶近叶顶低能流体产生的主要原因。     

二元保形非对称膨胀喷管流场特性研究

利用数值模拟方法对一种与无人飞行器后体一体化设计的二元保形大宽高比非对称膨胀喷管在地面状态的流场特性进行了研究，获得了尾喷管推力性能和三维流动特征随落压比的变化趋势。结果表明：虽然二元保形非对称膨胀喷管沿横向存在非等强度膨胀，但在研究范围内最佳落压比仍主要取决于上方短膨胀面结束位置面积与喉道面积之比；沿横向不等强度膨胀诱发的二次流及旋涡流动能够增强环境冷流与喷流之间的掺混；在研究的落压比范围内，随着落压比的增加喷管的推力性能变化很缓慢。     

1＋1/2对转涡轮非定常流动数值模拟研究

对转涡轮在航空燃气轮机设计中得到越来越多的重视,研究对转涡轮内部复杂流动对掌握对转涡轮的设计技术具有重要意义。本文利用数值模拟手段对所设计的1＋1/2对转涡轮内部非定常流动进行了模拟,并将定常和非定常结果进行了详细的对比分析,结果表明：非定常结果与定常结果相比出功比减小,总效率约减小0.44个百分点,流量基本不变,其中尾迹、激波、位势作用以及泄漏流等因素之间的相互作用是影响非定常特性的主要因素。     

离心叶轮和扩压器相互作用研究

采用定常和非定常数值模拟技术,研究了某跨音离心压气机级内的复杂流动,分析了叶轮与径向扩压器之间的非定常相互作用。结果表明,扩压器的势干扰使叶轮出口静压发生周期性地变化,引起叶轮后部负荷、叶尖泄漏和损失等也产生周期性地变化,影响范围达30％流向弦长。叶轮出口流场的周向不均匀性及非定常性使扩压器进口参数发生周期性的变化,导致扩压器负荷、总压恢复系数分布呈现出较强的非定常性,影响范围贯穿整个扩压器通道。     

真空衰减法测试无菌药品包装密封完整性过程中关键参数的考察

研究了影响真空衰减法测试无菌药品包装密封完整性时的关键参数。首先，确定了影响真空衰减法测试结果的关键参数，即试验环境、腔体死腔体积、腔体密封性、腔体材质和过程参数；然后通过设计和制定研究方案，对关键参数的影响逐一开展试验进行验证。结果表明，测试结果会受到上述关键参数的影响。推荐将试验环境控制在23℃、相对湿度45%；选用的腔体应尽量贴合试验样品的外形尺寸，并定期更换密封圈；腔体和阴性样品的材质推荐选用性能较稳定、灵敏度高的不锈钢材质；阴性样品应尽量在待测样品的基础上制备实心或不漏的样品；过程参数的设置需要在不同包装形式和不同内容物的基础上，充分考虑样品可能的泄漏风险点。实际测试时还需要合理设计和选择关键参数，以保证测试结果的科学性。     

不可压缩平板边界层转捩中突变过程的数值模拟

采用时间模式对不可压平板边界层从层流到湍流的转捩过程进行了直接数值模拟。分析结果表明：在层流-湍流转捩的突变过程开始之前，已经产生非线性作用；二维波与三维波的幅值实际增长率也偏离线性状态，而且在二者之间存在能量转移的迹象。在突变过程中，速度变形率对总应力的影响较大，在转捩结束后雷诺应力对总应力的影响比较显著。研究表明：正是由于大量谐波被快速激发并增大，导致了雷诺应力及其法向梯度也快速增大。这使得平均流剖面快速被修正，流动快速转为湍流。     

一种基于有限元/边界元耦合方法的管道进口声传播及声辐射模型

本文发展了一种基于有限元和边界元耦合方法的管道进口声传播及声辐射计算模型。该模型将整个声场分为内部有限域和外部无界域，分别用有限元和边界元方法求解控制方程，在二者之间的界面上使用具有物理意义的声阻抗参数进行匹配，并通过一种快速迭代方法实现全声场求解。这种迭代方法可以保证有限元刚度矩阵等带宽以及对称的特性不被破坏，有助于提高计算效率。该模型先得到了Levine and Schwinger标准解的检验，进而在无流动情况下对于简化的航发短舱进口管道模型进行了噪声辐射现象的数值模拟，最后基于计算结果分析了声衬对远场声辐射的影响。     

直升机用轴流风机内部流动分析

本文通过理论分析、数值仿真与试验比较相结合的方法，对某型直升机用轴流风机不同工况下的内部流动进行了分析。结果表明，叶轮内部相对速度分布的理论假设适用于额定工况，但不适用于小流量工况。当直升机高空飞行时，风机工作流量低于额定工况，叶顶处容易出现回流，二次流损失加剧；同时飞行高度增加还易导致边界层分离、射流-尾迹区域扩大，从而使风机效率进一步降低；低能流体的集中，促使叶轮失速往往首先从叶顶处出现。在设计直升机滑油系统用轴流风机时，应注意对其变工况性能进行研究，对影响变工况下叶轮内部流动损失的主要气动参数进行优化设计，以提高系统高空工作的稳定性。     

一种大负荷低压涡轮叶型的气动性能

基于Lantry-Menter转捩模型，分别对Zweifel升力系数为1.2的一种大负荷低压涡轮叶型在定常来流不同湍流度、雷诺数条件下，和上游非定常、周期性尾迹作用下的流动进行了数值模拟。计算结果表明,定常来流低雷诺数条件下，湍流度对该大负荷叶型的气动性能影响较大；上游非定常、周期性尾迹对叶型吸力面分离泡的抑制作用可进一步减小低雷诺数条件下的叶型损失。计算结果揭示了该大负荷叶型在低压涡轮内部真实流动环境中的表面流动及损失特征，对国内现行低压涡轮设计有着较好的启示。     

The effect of process variables on the degradation and physical properties of spray dried insulin intended for inhalation

The aim of this study was to investigate the effect of process variables on the degradation and physical properties of spray dried insulin intended for inhalation. A 2(4) full factorial experimentally designed study was performed to investigate the influence of the following independent spray drying variables: feed flow rate, nozzle gas flow rate, inlet air temperature and aspirator capacity (drying gas flow rate). Human insulin (biosynthetic and Ph.Eur. quality) was dissolved in distilled water to concentrations of 5 mg/ml. The solutions were spray dried in a Mini Spray Dryer Büchi and the dry powders produced were characterized by high performance liquid chromatography, size exclusion chromatography, laser diffraction, thermo gravimetric analysis, scanning electron microscopy and weighing. The degradation of insulin was found to be affected mainly by the process variables that determine the outlet air temperature, i.e.: inlet air temperature, aspirator capacity and feed flow rate. The outlet air temperature should be kept below 120 degrees C to avoid degradation. A statistical optimization of the spray drying variables was performed, and found to recommend an experiment with an outlet air temperature of 61+/-4 degrees C. This experiment ought to generate a yield of 54+/-7% by weight of particles with a mass median diameter 2.9+/-0.4 microm, moisture content 3.9+/-0.5% by weight, content of high molecular weight proteins 0.3+/-0.1% by area, A-21 desamido insulin 0.3+/-0.05% by area and other insulin related compounds 0.3+/-0.1% by area.     

Expression and inducibility of members in the cytochrome P4501 (CYP1) family in ringed and grey seals from polluted and less polluted waters

The expression and inducibility of cytochrome P4501A (CYP1A) were investigated in hepatic microsomes of ringed seals (Phoca hispida) and grey seals (Halichoerus grypus) from polluted (Baltic Sea) and less polluted (Svalbard and Sable Island) areas. Liver CYP1A protein levels and activities were assessed by immunoblot analysis and determining catalytic activities towards ethoxyresorufin (EROD) and pentoxyresorufin (PROD). The amount of CYP1A apoprotein and its catalytic activity were increased up to 5-fold in Baltic ringed and grey seal populations in comparison with ringed seals from Svalbard and grey seals from Sable Island. EROD and PROD activities correlated in all seal groups, indicating catalysis by the same CYP form(s). Enzyme kinetic studies suggested that PROD activity is catalysed by CYP1A enzymes in both ringed and grey seals. In immunoblot analysis, a protein was revealed in liver with an antibody against human CYP1B1, indicating that a CYP1B1 like protein could be present in ringed and grey seals. In conclusion, these data strengthen the concept that CYP1A is markedly induced in seals living in polluted waters and that both EROD and PROD activities are mediated by CYP1A forms in the seal liver. In addition, this study provides the first evidence for the presence of a CYP1B like protein in seal liver.     

Effects of altered exposure chamber pressure on the breathing pattern of conscious rats in nose-only exposure tubes

Rats exposed to inhaled toxicants while in plethysmographs having nose or neck seals may breathe against a negative pressure gradient during exposure. Breathing against negative pressure might affect the respiratory pattern and thus, the uptake or deposition of toxicant. The respiration of 10 conscious rats restrained in plethysmographic nose-only inhalation exposure tubes having a neck seal, was measured during breathing against ambient, negative and positive pressures (0 to +/- 7.5 cm H2O). Negative pressure increased respiratory frequency and reduced tidal volume, but minute volume was little changed. The estimated fraction of inspirate reaching the alveoli was reduced and inspiratory flow was increased. The magnitudes of these changes were small at typical exposure pressures, and the magnitudes of their effects on uptake and deposition would be expected to fall within the range of normal intersubject variability. Positive pressure tended to have effects opposite those of negative pressure.     

Proliferative effects of estradiol, progesterone, and two CB congeners and their metabolites on gray seal (Halichoerus grypus) uterine myocytes in vitro.

Gray seal females living in the Baltic Sea have been found to exhibit a high prevalence of uterine leiomyomas. These animals are also known to accumulate lipid-soluble PCBs in their blubber. PCBs have documented endocrine-disrupting effects; to investigate whether the PCBs could be part of the genesis of uterine smooth muscle tumors in this species, gray seal myometrial cell cultures were exposed to two CBs and their metabolites, as well as to estradiol and progesterone, after which the effects were analyzed in terms of proliferative activity by measurements of BrdU absorbance and protein content. Progesterone was found to have an inhibitory effect, whereas one CB acted as a stimulant on the myometrial cell proliferation. One of the CB metabolites also seemed to have an inhibitory effect, although this could not be statistically verified. These results suggest that some CBs have effects on uterine myometrial cell proliferation in gray seals and, thus, may also take part in the growth regulation of uterine leiomyomas.     

Characterization of calcitonin-containing liposome formulations for intranasal delivery

Calcitonin-containing liposome formulations were characterized to obtain information for evaluation of their feasibility in intranasal delivery. The parameters of liposomal charge characteristics, charge inducing agent concentration, calcitonin concentration and pH of the medium on the loading efficiency and leakage behaviour, and the chemical stability of calcitonin in liposomes were investigated. Results showed that the loading efficiency of calcitonin increased with increasing the added concentration of calcitonin. The magnitude of the loading efficiency due to the liposomal charge of negative, positive and neutral characteristics was in the order of negatively charged liposome > neutral liposome > positively charge liposome. The increase of molar ratio of phosphatidylserine in liposomes showed an increase of loading efficiency; while, the increase of molar ratios of stearylamine showed a decrease of loading efficiency. The loading efficiency at pH 7.4 was greater than that at pH 4.3. The leakage of positively charged liposomes was greater than that of neutral and negatively charged liposomes. The leakage at pH 4.3 was faster than that at pH 7.4. The leakage of positively charged liposomes increased as temperature increased. The chemical stability of calcitonin in both solution and liposomes demonstrated a pseudo-first-order kinetic degradation. Less degradation was observed at pH 3.4 and 4 degrees C. The degradation rate of calcitonin in solution, or in positively charged, negatively charged, and neutral liposomes, exhibited no significant difference. The particle size of the calcitonin-containing liposomes after storage for 1 month at pH 4.3 and 4 degrees C showed little change.     

Characterization of calcitonin-containing liposome formulations for intranasal delivery

Calcitonin-containing liposome formulations were characterized to obtain information for evaluation of their feasibility in intranasal delivery. The parameters of liposomal charge characteristics, charge inducing agent concentration, calcitonin concentration and pH of the medium on the loading efficiency and leakage behaviour, and the chemical stability of calcitonin in liposomes were investigated. Results showed that the loading efficiency of calcitonin increased with increasing the added concentration of calcitonin. The magnitude of the loading efficiency due to the liposomal charge of negative, positive and neutral characteristics was in the order of negatively charged liposome > neutral liposome > positively charge liposome. The increase of molar ratio of phosphatidylserine in liposomes showed an increase of loading efficiency; while, the increase of molar ratios of stearylamine showed a decrease of loading efficiency. The loading efficiency at pH7.4 was greater than that at pH4.3. The leakage of positively charged liposomes was greater than that of neutral and negatively charged liposomes. The leakage at pH4.3 was faster than that at pH7.4. The leakage of positively charged liposomes increased as temperature increased. The chemical stability of calcitonin in both solution and liposomes demonstrated a pseudo-first-order kinetic degradation. Less degradation was observed at pH3.4 and 4°C. The degradation rate of calcitonin in solution, or in positively charged, negatively charged, and neutral liposomes, exhibited no significant difference. The particle size of the calcitonin-containing liposomes after storage for 1 month at pH4.3 and 4°C showed little change.     

In vitro stability and permeability studies of liposomal delivery systems for a novel lipophilic endomorphin 1 analogue

The influence of inlet air humidity variations on fluid bed drying end-point detection was the primary focus here. Various drying end-point criteria based on temperature and humidity measurements were compared. Seasonally changing inlet air humidity affects the moisture content of the finished granules, as long as the drying process remains unchanged. However, a specific moisture content of the finished granules is commonly desired after fluid bed drying. When experimental batches of varying inlet air humidity were compared at the beginning of the drying phase, the temperature of the granules increased linearly as the humidity of the inlet air increased. This effect causes variation in moisture contents of the final granules of different batches when the fixed temperature of the mass is used as an end-point criterion. With varying inlet air humidity, the often used ΔT temperature difference method resulted in more precise estimation of the drying end-point than the constant temperature criterion. In this study new insights were found into the correlation between moisture content and temperature of the fluidising mass. Fluidisation activity greatly affected detection of drying end-point. Use of the ΔT criterion requires proper fluidisation throughout the process.     

Influences of heat seal lacquer thickness on the quality of blister packages

A sealability of aluminium lidding foils against formable polymer materials of blister packages is usually achieved by a coating of aluminium with certain grammages of heat seal lacquers. To investigate influences of their thickness on quality of blister packages, lidding foils with different grammages of two lacquer types were manufactured. Sealing experiments (variation of temperature, pressure and sealing time) were performed. Sealed seam strengths were determined with mechanical tensile tests, tightness of cold form blisters were analysed by means of helium leakage tests. Time-dependent moisture uptake of stored blisters was monitored with micro-gas chromatography. By means of a simple calculation model the permeability coefficients of the heat seal lacquers were determined. Lidding foils with higher lacquer grammages showed significantly greater sealed seam strengths. Helium leakage tests showed only slight effects of heat seal lacquer grammage on tightness of blisters. But cold form blisters with lidding foils of higher lacquer grammages showed a significantly greater moisture uptake. Since the heat seal lacquers and the rigid polyvinyl chloride of the formable aluminium compound foils had similar permeability coefficients, the contribution of the lacquers to the total permeability of the investigated cold form blisters was only slightly.     

Comparison of polychlorinated biphenyl (PCB) induced effects on innate immune functions in harbour and grey seals

Polychlorinated biphenyls (PCBs) are known to have detrimental effects on the innate immune system of several mammalian species. Top predators such as marine mammals may be badly affected as PCBs can bioaccumulate in their blubber to high concentrations and previous studies have suggested that harbour seals may be particularly vulnerable to the immunotoxic effects of such contaminants. To investigate the effects of PCBs on innate immune functions in phocid seals, blood samples were collected from harbour and grey seals and exposed in vitro to a mixture of Aroclors. Separated mononuclear (PBMCs) and polymorphonuclear (PMNCs) leukocytes from each species were incubated with Aroclors (at 3 and 30 ngml(-1)) for 3 and 24 h incubation periods, after which phagocytosis, respiratory burst and cytotoxic activity were measured. The phagocytic activity of harbour seal PMNCs was decreased at both incubation times and at both Aroclor concentrations tested, but there was no effect on the grey seals. Similarly, the respiratory burst activity of harbour seals was decreased at both incubation times, but only at the higher concentration used. There were no differences in the cytotoxic activity of the PBMCs with respect to incubation times or concentrations in either species. However, differences were observed in the level of cytotoxic activity against YAC-1 target cells, with the grey seal PBMCs showing higher levels of activity. The observed differences in phagocytosis, respiratory burst and cytotoxic activity of the leukocytes following incubation with PCBs may have implications for the previously recorded differences in disease susceptibility between grey and harbour seals.