超声速燃烧气动斜坡喷注器研究

为增强超声速燃烧过程的燃料混合，设计了通过喷嘴阵列形成流向涡强化混合的气动斜坡实验件。在直联式实验台上对气动斜坡实验件进行了纹影及油流谱等冷试实验研究。并采用大涡模拟（LES）方法数值模拟了超声速流场中气动斜坡的流动及燃烧特性。结果表明:气动斜坡喷注器的喷嘴阵列设计能有效加速喷流后流向涡的卷起，提高掺混特性；其燃烧过程也能使喷流形成的剪切层上抬，增进混合；由于喷流方向与主流方向夹角较小，总压损失也较物理斜坡、横向喷流等混合增强方式小。     

Internet访问时间的混沌性解析

以CAIDA组织授权的海量数据为样本空间,利用相空间重构技术以及G-P算法,对时间维的Internet访问时间进行相空间重构,得到其混沌吸引子饱和关联维数为2.8308,证实Internet访问时间的演化过程具有混沌特征.在此基础上,根据关联维数及奇怪吸引子在相空间混沌轨道运动的特性,提出了三维微分方程组的Internet访问时间长期预测模型.     

用双流体模型模拟超声速气固两相流动

采用了双流体模型对Jet Propulsion Laboratory（JPL）喷管中气固两相流动以及超声速射流两相流动进行了数值模拟，并研究了可压缩两相流动中气相与颗粒的相互作用规律。自主开发的一般曲线坐标系下二维轴对称可压缩双流体程序Solve2D，对气相求解Navier-Stokes(N-S)方程组，采用k-ε湍流模型，颗粒相求解Euler方程组。对JPL喷管内的两相流场和湍流两相射流流场进行了数值模拟，研究了不同颗粒质量载荷以及不同直径颗粒时的气固两相流场的流动规律。     

醋酸钙梯度法制备维A酸脂质体

目的:评价醋酸钙梯度法制备维A酸脂质体的可行性,并与薄膜法、逆相蒸发法进行质量比较。方法:采用薄膜法、逆相蒸发法和醋酸钙梯度法分别制备维A酸脂质体,用G-50葡聚糖凝胶柱分离,以紫外分光光度法和纳米激光粒度仪分别测定维A酸脂质体的包封率和粒径,以电子显微镜观察维A酸脂质体的形态。结果:以醋酸钙梯度法制备的维A酸脂质体包封率最高,达90.48%;其外观圆整均匀,平均粒径为35.8nm,4℃放置3mo质量稳定。结论:采用醋酸钙梯度法制备维A酸脂质体包封率较高,方法可行。     

两相圆湍射流颗粒弥散与速度相似性大涡模拟

气相采用大涡模拟方法颗粒相采用拉格朗日轨道模型对高雷诺数两相圆湍射流进行了数值模拟，研究了一种中等Stokes颗粒在大尺度涡结构中弥散特点以及两相速度统计特征。研究表明，颗粒弥散同时受流动涡结构和颗粒惯性决定，颗粒在涡结构的边缘或者涡与涡交织区域浓度高，形成倾向性分布。沿中心轴线两相平均速度衰减不同，颗粒相速度衰减慢于气相。射流近场两相速度沿径向变化显著，在射流远场两相平均速度都具有相似性，沿径向颗粒相平均速度衰减慢、分布平稳。     

小白菜花叶病流行曲线分析及两参数植病流行方程的非线性拟合

小白菜花叶病流行曲线分析表明,Weibull方程拟合效果最好,Logistic方程次之,Gompertz方程又次之。 探讨了两参数植病流行方程的非线性拟合方法:台劳级数展开法和麦夸尔特法。在小白菜花叶病等18个植病系统的94组流行曲线中,非线性方法的拟合结果均优于线性方法。     

不同制备方法对尼莫地平脂质体体外性质的影响

目的考察不同制备方法对尼莫地平脂质体体外性质的影响,优选出较好的制备方法。方法分别以薄膜分散法、逆相蒸发法、高压乳匀法制备尼莫地平脂质体,用透射电镜观察其形态,测定其包封率。结果所制得的尼莫地平脂质体形态较圆整,分布较均匀,包封率：薄膜分散法＞高压乳匀法＞逆相蒸发法;粒径：薄膜分散法＞逆相蒸发法＞高压乳匀法。结论尼莫地平脂质体体外质量与制备方法密切相关。     

米托蒽醌脂质体制备工艺的研究

目的：优选米托蒽醌脂质体制备工艺。方法：以用形态、粒径、包封率为指标评价工艺。结果：逆相蒸发法制备的的脂质体粒径小,包封率高。结论：逆相蒸发法可用作米托蒽醌脂质体的制备工艺。     

二维带动力吸气式高超声速飞行器绕流的PNS-NS混合求解

对于数值模拟高超声速飞行器带动力整机流动,采用单纯的时间迭代方法非常耗时。本文结合空间推进求解PNS方程和时间迭代求解NS方程的CFD方法来模拟高超声速飞行器整机流动。高超声速飞行器的流场是超声速占主导的,但在流场中也存在局部分离以及亚声速占主导的区域。本文采用的CFD方法,在超声速占主导的流动区域采用空间推进求解PNS方程的方法,在亚声速和分离区采用时间迭代求解NS方程的方法,整机流动在划分的各个区域之间自动推进求解。对于求解带动力高超声速二维整机流动,目前的CFD方法在大大节约计算时间和计算资源的同时,可以得到和完全时间迭代方法同等准确的数值模拟结果。     

紫杉醇脂质体的制备和质量评价

目的：对紫杉醇脂质体的工艺研究和含量测定方法进行考察,并评价其质量,方法：用逆相蒸发法制备紫杉醇脂质体,并对其形态学、包封率和PH值等性质进行了研究,结果：紫杉醇脂质体平均粒径为379nm,包封率为98．085,PH7．16。结论：选择逆相蒸发法优化工艺制备杉醇脂质体可行,为开发紫杉醇新型静脉注射剂提供了实验依据。     

Effect of expansion chamber geometry on atomization and spray dispersion characters of a flashing mixture containing inerts. Part I. Numerical predictions and dual laser measurements

A cigarette alternative is designed to deliver a dose of medicinal nicotine within a timeframe comparable to that of a cigarette, and gives much of what smokers expect from a cigarette without the risks of smoking tobacco. The design concept is the same as a pressurized metered dose inhaler (pMDI), but is a breath actuated device (Oxette(?)). This work predicts the residual mass median diameter (MMD) of the spray issuing from early stage Oxette(?) prototypes by using an evaporation model of multi-component liquid droplets with the help of a numerical multi-component two-phase actuation model (developed by the authors) to quantify the sprays. Two different formulations with 95% and 98% mass fraction of HFA 134a, and two prototypes of cigarette alternatives with different expansion chamber volumes have been analyzed by the numerical model and compared with laser based measurements. The later designed device provides a larger expansion chamber volume to enhance the propellant evaporation, recirculation, bubble generation and growth inside the chamber, and it makes a significant improvement to produce finer sprays than the earlier design. The mass fraction of the formulation does not affect significantly on the initial MMD of the droplets near the discharge orifice. However, it influences the residual MMD at x=100mm from the discharge orifice, where the ratio of the predicted residual MMDs of the droplets generated by the formulations with 98% and 95% of HFA 134a is 0.73. Although the formulation with 98% of HFA 134a can generate smaller droplets, the formulation with 95% of HFA 134a produces more steady puffs with relatively low mass flow rate.     

Biodegradable submicron carriers for peptide drugs: Preparation of dl-lactide/glycolide copolymer (PLGA) nanospheres with nafarelin acetate by a novel emulsion-phase separation method in an oil system

PLGA nanospheres, biodegradable polymeric carriers for peptide drugs, were prepared by a novel emulsion-phase separation method. The preparation was carried out in an oil phase system in order to improve the entrapment efficiency of water-soluble peptide. An LH-RH analogue (nafarelin acetate (NA)) was employed as a model peptide drug to investigate the encapsulation efficiency. An aqueous solution of the drug was emulsified by addition with stirring to a dichloromethane-acetone mixture containing dissolved PLGA. The gradual addition of Triester oil (caprylate and caprate triglyceride) into the resultant w/o emulsion induced phase separation of PLGA at the interface of aqueous droplets. It was found that the aqueous droplets effectively worked as a coacervation-inducing agent of the polymer. PLGA coacervates precipitated around the aqueous emulsion droplets containing the peptide which were hardened by evaporation of the solvent, producing spherical drug carriers. The presence of surfactant significantly reduced the size of the aqueous droplets, resulting in submicron-sized PLGA spheres (mean diameter, 500–800 nm). The recovery of drug entrapped in the nanospheres was markedly increased compared with our previous preparation technique in a water system. Further, optimum conditions in the present method for preparing nanospheres were established to enhance the recovery of nanospheres and the efficiency of drug entrapment.     

Production methods for nanodrug particles using the bottom-up approach

This review focuses on bottom-up processes such as precipitation (or crystallisation) and single droplet evaporation to produce nanoparticles containing largely pure therapeutics for pharmaceutical applications. Suitable precipitation techniques involve the use of high-gravity, confined impinging liquid jet mixing, multi-inlet vortex mixing, supercritical fluids, and ultrasonic waves. Droplet evaporation methods are spray-based, including nanospray drying, aerosol flow reactor method, spraying of low-boiling point solvent under ambient conditions and electrospraying of low-electrical conducting solutions. A key to the success of yielding stable nanoparticles in these various techniques is to control the particle growth kinetics through evaporation rate of the droplets or mixing rate during precipitation.     

Kinetics of propranolol uptake in muscle, skin, and fat of the isolated perfused rat hindlimb.

The tissue distribution kinetics of a highly bound solute, propranolol, was investigated in a heterogeneous organ, the isolated perfused limb, using the impulse-response technique and destructive sampling. The propranolol concentration in muscle, skin, and fat as well as in outflow perfusate was measured up to 30 min after injection. The resulting data were analysed assuming (1) vascular, muscle, skin and fat compartments as well mixed (compartmental model) and (2) using a distributed-in-space model which accounts for the noninstantaneous intravascular mixing and tissue distribution processes but consists only of a vascular and extravascular phase (two-phase model). The compartmental model adequately described propranolol concentration-time data in the three tissue compartments and the outflow concentration-time curve (except of the early mixing phase). In contrast, the two-phase model better described the outflow concentration-time curve but is limited in accounting only for the distribution kinetics in the dominant tissue, the muscle. The two-phase model well described the time course of propranolol concentration in muscle tissue, with parameter estimates similar to those obtained with the compartmental model. The results suggest, first that the uptake kinetics of propranolol into skin and fat cannot be analysed on the basis of outflow data alone and, second that the assumption of well-mixed compartments is a valid approximation from a practical point of view (as, e.g., in physiological based pharmacokinetic modelling). The steady-state distribution volumes of skin and fat were only 16 and 4%, respectively, of that of muscle tissue (16.7 ml), with higher partition coefficient in fat (6.36) than in skin (2.64) and muscle (2.79).     

Prediction of mechanical properties of compacted binary mixtures containing high-dose poorly compressible drug

The aim of the study was to develop, compare and validate predictive model for mechanical property of binary systems. The mechanical properties of binary mixtures of ibuprofen (IBN) a poorly compressible high dose drug, were studied in presence of different excipients. The tensile strength of tablets of individual components viz. IBN, microcrystalline cellulose (MCC), and dicalcium phosphate dihydrate (DCP) and binary mixtures of IBN with excipients was measured at various relative densities. Prediction of the mechanical property of binary mixtures, from that of single components, was attempted using Ryshkewitch-Duckworth (R-D) and Percolation theory, by assuming a linear mixing rule or a power law mixing rule. The models were compared, and the best model was proposed based on the distribution of residuals and the Akaike's information criterion. Good predictions were obtained with the power law combined with linear mixing rule, using R-D and Percolation models. The results indicated that the proposed model can well predict the mechanical properties of binary system containing predominantly poorly compressible drug candidate. The predictions of these models and conclusions can be systematically generalized to other pharmaceutical powders.     

N2O_HTPB固液火箭发动机喷管两相流计算

利用二维轴对称N-S方程对选用氧化亚氮/丁羟基燃料推进剂的固液混合火箭发动机的喷管两相流进行了计算。计算采用MacCormack时间推进预报校正二步格式,采用了Baldwin－Lomax代数湍流模型和两相平衡流模型。计算了三种氧燃比下四个不同喷管的喷管流场参数,并计算了喷管性能,通过比较两相流和气相流的计算结果,分析了不同氧燃比和喷管形状对喷管性能的影响,认为固液火箭发动机的性能主要受氧燃比的影响,为固液混合火箭发动机的设计提供了依据。     

In vivo evaluation of tablets and capsules containing spray-dried o/w-emulsions for oral delivery of poorly soluble drugs

It is recognised that poorly soluble drugs may show an increased oral bioavailability when incorporated in o/w-emulsions. Encapsulating the emulsion lipid droplets in hydroxypropyl methylcellulose (HPMC) by spray drying has been demonstrated to preserve an improved bioavailability releasing lipid droplets from the powder in vivo. However, the spray-dried powder is cohesive and bulky requiring additional processing to improve handling. This was resolved in previous work where a directly compressible dry emulsion formulation was described. The purpose of the present study is to investigate the oral bioavailability resulting from administration of a directly compressible dry emulsion as a tablet and compare it with a HPMC dry emulsion powder and a simple lipid solution. Four female Beagle dogs received a single dose of each formulation containing the same amount of medium-chain triglycerides (MCT) and a model drug, Lu 28-179. Cyclodextrin solutions administered orally and intravenously were used as references. The absolute bioavailability decreased in the order cyclodextrin solution (0.14), HPMC dry emulsion (0.11), technically improved dry emulsion (0.10) and MCT solution (0.06). The directly compressible dry emulsion tablets were concluded to be comparable to a HPMC dry emulsion powder in terms of bioavailability. The lack of statistically significant differences relative to a MCT solution was ascribed to a low and variable absolute oral bioavailability of the model drug.     

Preparation and in vitro evaluation of rosin microcapsules: solvent evaporation technique

Free flowing, spherical rosin microcapsules were prepared by a method based on phase separation by solvent evaporation. Bentonite was used to prevent the agglomeration and coalescence of the dispersed polymer droplets. The effect of varying the core to coat ratio on micrometric and dissolution properties has been described.     

Single-droplet evaporation kinetics and particle formation in an acoustic levitator. Part 1: evaporation of water microdroplets assessed using boundary-layer and acoustic levitation theories

The suitability of a single droplet drying acoustic levitator as a model for the spray drying of aqueous, pharmaceutically-relevant solutes used to produce protein-loaded particles has been examined. The acoustic levitator was initially evaluated by measuring the drying rates of droplets of pure water in dependence of drying-air temperature and flow rate. The measured drying rates were higher than those predicted by boundary layer theory because of the effects of primary acoustic streaming. Sherwood numbers of 2.6, 3.6, and 4.4 at drying-air temperatures of 25 degrees C, 40 degrees C, and 60 degrees C were determined, respectively. Acoustic levitation theory could predict the measured drying rates and Sherwood numbers only when a forced-convection drying-air stream was used to neuralize the retarding effect of secondary acoustic streaming on evaporation rate. At still higher drying-air flow rates, the Ranz-Marshall correlation accurately predicts Sherwood number, provided a stable droplet position in the standing acoustic wave is maintained. The measured Sherwood numbers and droplet Reynolds numbers show that experiments performed in the levitator in still air are taking place effectively under conditions of substantial forced convection. The similitude of these values to those occurring in spray dryers is fortuitous for the suitability of the acoustic levitator as a droplet evaporation model for spray drying.