激光诱导间质热疗方法的离体模拟实验研究

本文建立了激光诱导间质热疗方法 (LITT)的离体模拟实验系统 ,在不同的输出功率、不同的加热时间下 ,实验测量了激光加热时的离体猪肝组织温度分布和热凝结区域的大小 ,与计算机模拟的结果进行了对比。实验发现 ,在相同的功率和加热时间下 ,会出现有无碳化两种不同现象。当临近激光加入头表面的生物组织产生碳化时 。

人外周血淋巴细胞微核分析用于估算离体模拟局部照射剂量的研究

目的:探讨利用人外周血淋巴细胞微核分析估算局部照射剂量的可行性。方法:收集2例人外周血样本,每例血样分为两部分,一部分不照射,另一部分再分成两组分别于1和5 Gy的60Coγ射线下离体照射,剂量率为1 Gy/min。将来自同一样本的照射血与未照射血按1∶3或3∶1比例混合以模拟局部照射,共分析8组混合血样中双核淋巴细胞微核(MN)率,利用国际原子能机构(IAEA)推荐的Dolphin's模型推算混合血中受照血的微核率,并采用卫生行业标准(WS/T 178—1999)推荐的剂量效应曲线估算局部照射剂量。结果:各组混合血样MN分布均不符合泊松分布。1 Gy照射组估算的局部剂量与实际照射剂量偏差较大,5 Gy照射组估算的局部剂量与实际照射剂量较接近。结论:离体情况下,MN能较好的用于估算局部照射剂量,且MN可能更适用于较高剂量的估算。

胶布环绕包扎对肢体压力影响的离体模拟实验研究

目的离体模拟实验观察4种材质、1～3个皱褶胶布环绕包扎时对肢体压力的影响,以明确胶布环绕肢体包扎的安全性。方法将塑料胶布、纸质胶布、布质胶布、丝质胶布裁成宽1.0cm备用。将胶布环绕橡胶指套1周,其间分别捏起1～3个3mm皱褶,利用血压计分别测量皱褶完全打开时的压力。比较同材质胶布不同皱褶对肢体的压力影响以及同皱褶不同材质胶布对肢体压力的影响。结果同材质胶布中布质胶布和丝质胶布在2褶时失效压力最小,分别为(6.73±0.60)kPa和(7.15±0.95)kPa。不同材质胶布中2褶的布质胶布、丝质胶布的失效压力显著低于塑料、纸质胶布(均P<0.05)。其余组间失效压力比较,差异无统计学意义(均P>0.05)。结论在需要使用胶布环绕包扎肢体时使用2褶的丝质或布质胶布最为安全。

低浓度恩诺沙星在离体肠道模拟系统中对人体肠道菌群的影响

残留在食品中的抗菌药被人体摄入后可能会对人体肠道菌群产生影响。本研究采用模拟残留药物通过胃肠道的离体培养系统研究了低浓度恩诺沙星对人体肠道菌群(包括9种ATCC标准菌株和健康志愿者粪便菌群)的影响。结果表明:细菌在药物浓度大于5倍MIC的离体培养系统仍能增殖,系统中加入2～5μg/ml恩诺沙星可部分抑制产气荚膜梭菌、青春双歧杆菌和直肠真杆菌的生长。2μg/ml恩诺沙星可抑制正常人体粪便菌群中敏感大肠杆菌的生长。并使耐药大肠杆菌比例明显升高,对厌氧菌的抑制作用不明显。总之,低浓度恩诺沙星对正常人体粪便菌群的最重要影响也许是筛选出正常情况下仅占少量的肠道耐药菌,使耐药菌占优势。

腺苷酸环化酶介导电针预治疗对离体缺血心肌细胞的保护作用

目的:观察电针预治疗对模拟全心缺血心肌细胞的保护作用,并探讨β-AR信号转导站点中腺苷酸环化酶(adenylyl cyclase,AC)介导上述针刺保护效应中的作用。方法:采用离体心脏模拟全心缺血(低灌流)模型,观察正常对照(NC)组、缺血再灌注(IR)组和缺血再灌注+电针(EA)组心肌细胞存活率,心肌细胞内静息钙水平([Ca2+]i)以及各组心肌细胞在Forskolin作用下钙瞬变的变化。结果:EA组心肌细胞存活率明显高于IR组(P<0.01),其心肌[Ca2+]i明显低于IR组(P<0.01),且EA组缺血心肌细胞在Forskolin作用下钙瞬变增加的波幅与相应的IR组比较明显降低(P<0.01)。结论:电针预治疗可以有效地提高缺血心肌细胞的存活率,改善缺血心肌细胞内钙超载情况,抑制缺血引起的AC活性过度增加。

烟碱口腔跨膜扩散及其与黏蛋白作用机制研究

本文以离体猪口腔颊黏膜为载体,利用药物透皮扩散技术,对烟碱经口腔颊粘膜的扩散行为进行了初步研究;同时以牛颌下腺黏蛋白为受体大分子,利用多种光谱学方法和核磁共振技术,对烟碱与口腔黏蛋白的作用机制进行了考察。结果表明:1、碱性口腔环境更有利于烟碱的跨膜扩散;2、烟碱跨口腔颊黏膜的表观扩散系数为10-5数量级,高烟碱浓度下跨膜扩散具有更高的扩散速率及表观扩散系数;3、烟碱的吡咯环与牛颌下腺黏蛋白相互作用最强,pH是决定淬灭类型的关键因素,酸性条件下为动态淬灭,碱性条件为非经典静态淬灭;4、烟碱与牛颌下腺黏蛋白形成复合物,导致黏蛋白的二级结构发生改变。以上研究结果对口含烟开发和评价具有重要指导意义。

Numerical Simulation of Separating Gas Mixtures via Hydrate Formation in Bubble Column

To develop a new technique for separating gas mixtures via hydrate formation,a set of medium-sized experimental bubble column reactor equipment was constructed.On the basis of the structure parameters of the ex- perimental bubble column reactor,assuming that the liquid phase was in the axial dispersion regime and the gas phase was in the plug flow regime,in the presence of hydrate promoter tetrahydrofuran(THF),the rate of hydrogen enrichment for CH4+H2 gas mixtures at different operational conditions(such as temperature,pressure,concentra- tion of gas components,gas flow rate,liquid flow rate)were simulated.The heat product of the hydrate reaction and its axial distribution under different operational conditions were also calculated.The results would be helpful not only to setting and optimizing operation conditions and design of multi-refrigeration equipment,but also to hydrate separation technique industrialization.

Numerical simulation of temperature and velocity fields in plasma spray

Based on the turbulence jet model, with respect to Ar-He mixture plasma gas injecting to ambient atmosphere, the temperature filed and velocity field under typical working conditions were investigated. Given the conditions of I=900 A, FAr= 1.98 m^3/h, FEe=0.85 m^3/h, it is found that both the temperature and the velocity undergo a plateau region near the nozzle exit （0-10 mm） at the very first stage, then decrease abruptly from initial 13 543 K and 778.2 m/s to 4 000 K and 260.0 m/s, and finally decrease slowly again. Meanwhile, the radial temperature and radial velocity change relatively slow. The inner mechanism for such phenomena is due to the complex violent interaction between the high-temperature and high-velocity turbulent plasma jet and the ambient atmosphere. Compared with traditional methods, the initial working conditions can be directly related to the temperature and velocity fields of the plasma jet by deriving basic boundary conditions.

Numerical simulation of three-dimensional combustion flows

A finite-rate method is used to simulate the three-dimensional combustion process in a plasma generator with CH4 as the fuel. The simulation was run with RNG k-ε model to simulate turbulence, with eddy-dissipation-concept (EDC) model to simulate the combustion and with discrete ordinates model to simulate radiation. The numerical results show that the flow field characteristics and the parameter distributions are under the condition of rich fuels, and these results provide valuable information when optimizing the plasma generator design and organizing its flow fields.

Structures and Dynamics of a Two-Dimensional Confined Dusty Plasma System

The influence of the confining potential strength and temperature on the structures and dynamics of a two-dimensional (2D) dusty plasma system is investigated through molecular dynamic (MD) simulation. The circular symmetric confining potential leads to the nonuniform packing of particles, that is, an inner core with a hexagon lattice surrounded by a few outer circular shells. Under the appropriate confining potential and temperature, the particle trajectories on middle shells form a series of concentric and nested hexagons due to tangential movements of particles.Mean square displacement, self-diffusion constant, pair correlation function, and the nearest bond are used to characterize the structural and dynamical properties of the system. With the increase of the confining potential, the radial and tangential movements of particles have different behaviors. With the increase of temperature, the radial and tangential motions strengthen, particle trajectories gradually become disordered, and the system gradually changes from a crystal or liquid state to a gas state.

CFD-DEM simulation of fluid-solid flow of a tapered column separation bed

Research on recycling waste Printed Circuit Boards(PCB) is at the forefront of preventing environmental pollution and finding ways to recycle resources.The Tapered Column Separation Bed(TCSB) is invented aiming at disposing the problem that fine particles of waste printed circuit boards cannot be separated efficiently so as to obtain further insight about the underlying mechanisms and demonstrate the separation feasibility in the tapered column separation bed.In this work,a Computational Fluid Dynamics(CFD) coupled with Discrete Element Method(DEM) model for two-phase flow has been extended to simulate the fluid-solid flow in the tapered column separation bed.Its validity is demonstrated by its successful capturing the key features of particles' flow pattern,velocity,the pressure distribution,the axial position with time and axial force for particles with different densities.Simulation results show that the plastic particles and resin particles become overflow,while copper particles,iron particles and aluminum particles successively become underflow,with a discharge water flow rate of 1 m^3/h,an obliquity of 30°.The simulated results agree reasonably well with the experimental observation.Using this equipment to separate waste PCBs is feasible,theoretically.

Molecular Simulation of CO2/H2 Mixture Separation in Metal-organic Frameworks： Effect of Catenation and Electrostatic Interactions

In this work grand canonical Monte Carlo simulations were performed to study gas separation in three pairs of isoreticular metal-organic frameworks (IRMOFs) with and without catenation at room temperature.Mixture composed of CO2 and H2 was selected as the model system to separate.The results show that CO2 selectivity in catenated MOFs with multi-porous frameworks is much higher than their non-catenated counterparts.The simulations also show that the electrostatic interactions are very important for the selectivity,and the contributions of different electrostatic interactions are different,depending on pore size,pressure and mixture composition.In fact,changing the electrostatic interactions can even qualitatively change the adsorption behavior.A general conclusion is that the electrostatic interactions between adsorbate molecules and the framework atoms play a dominant role at low pressures,and these interactions in catenated MOFs have much more pronounced effects than those in their non-catenated counterparts,while the electrostatic interactions between adsorbate molecules become evident with increasing pressure,and eventually dominant.

A new complete model of switch-mode plasma cutting power supply

A complete model of switch-mode plasma cutting power supply and its simulation are developed. The full bridge isolated pulse width modulation (PWM) buck converter in continuous conduction mode (CCM) for high watt plasma power supply is approached. Reduced ripple current and improved power factor are achieved in the plasma power supply. With a PID control strategy, circuit responses become more stable and faster with low overshoot during load and current changing. The converter achieved high efficiency under 3 to 15kW load conditions.

Molecular Dynamics Simulation for the Binary Mixtures of High Pressure Carbon Dioxide and Ionic Liquids

Molecular dynamics simulation with an all-atom force field has been carded out on the two binary sys- tems of [bmim][PF6]-CO2 and [bmim][NO3]-CO2 to study the transport properties, volume expansion and micro- structures. It was found that addition of CO2 in the liquid phase can greatly decrease the viscosity of ionic liquids （ILs） and increase their diffusion coefficient obviously. Furthermore, the volume expansion of ionic liquids was found to increase with the increase of the mole fraction of CO2 in the liquid phase but less than 35% for the two simulated systems, which had a significant difference with CO2 expanded organic solvents. The main reason was that there were some void spaces inter and intra the molecules of ionic liquids. Finally, site to site radial distribution functions and corresponding number integrals were investigated and it was found that the change of microstructures of ILs bv addition CO2 had a great influence on the orooerties of ILs.

Direct Numerical Simulation of Particle Dispersion in Gas-Solid Compressible Turbulent Jets

A numerical method was developed to directly simulate the compressible, particle-laden turbulent jets.The fourth order compact finite difference schemes were used to discretize the space derivatives. The Lagrangian method was adopted to simulate the particle motion based on one-way coupling. It is found that the turbulent intensity profiles attain self-similar status in the jet downstream regions. At the Stokes number of 1, particles are concentrated largely in the outer boundaries of the large-scale vortex structures with the most uneven distribution and the widest dispersion in the lateral direction. Particles at the much smaller Stokes numbers are distributed evenly in the flow field, and the lateral dispersion is also considerable. Distribution of particles at much larger Stokes numbers is more uniform and the lateral dispersion becomes small. In addition, the inflow conditions have different effects on the particle dispersion. The direct numerical simulation (DNS) results accord with the previous experiments and numerical studies.

Numerical simulation of the pulsing air separation field based on CFD

The flow field of pulsing air separation is normally in an unsteady turbulence state.With the application of the basic principles of multiphase turbulent flows,we established the dynamical computational model,which shows a remarkable variation of the unstable pulsing air flow field.CFD(computational fluid dynamics) was used to conduct the numerical simulation of the actual geometric model of the classifier.The inside velocity of the flowing fields was analyzed later.The simulation results indicate that the designed structure of the active pulsing air classifier provided a favorable environment for the separation of the particles with different physical characters by density.We shot the movement behaviors of the typical tracer grains in the active pulsing flow field using a high speed dynamic camera.The displacement and velocity curves of the particles in the continuous impulse periods were then analyzed.The experimental results indicate that the effective separation by density of the particles with the same settling velocity and different ranges of the density and particle size can be achieved in the active pulsing airflow field.The experimental results provide an agreement with the simulation results.

Simulation of DPM distribution in a long single entry with buoyancy effect

Diesel particulate matter(DPM) is considered carcinogenic after prolonged exposure. With more dieselpowered equipment used in underground mines, miners' exposure to DPM has become an increasing concern. This paper used computational fluid dynamics(CFD) method to study DPM distribution based on an experiment conducted by the Diesel Emissions Evaluation Program(DEEP) in Canada. Twenty-four cases were simulated where the emissions from both truck and load-haul-dumps(LHDs) were examined.Each vehicle was placed in two stream wise locations, and the vehicles were oriented either facing or with the rear end toward the main fresh airflow. A species transport model with buoyancy effect was then used to examine the DPM dispersion pattern. High DPM regions were identified downstream,around, and even upstream of diesel engines. This can provide guidelines for good working practices and selection of diesel emission reduction technologies underground.

A single-phase turbulent flow numerical simulation of a cyclonic-static micro bubble flotation column

Improved fluid dynamics can enhance the separation efficiency of flotation methods. A Computational Fluid Dynamics simulation using FLUENT was performed to model the fluid environment of a cyclonic-sta- tic micro bubble flotation column. The simulation results visually show the interior flow and illustrate mix- ing of the different flows within the apparatus. An analysis of the distribution in velocity and vorticity was used to analyze the separation mechanism and the synergism of the component parts and to strengthen the design of each unit. The conclusions are that axial back mixing and vortexes still exist in the separation unit even in the presence of packing media. The inverted cone structure near the tangential inlet （cone 1 ） within the cyclonic unit is the main reason for this. The cone 1 structure enhances swirling and focuses energy within the inner area of the cone where there are abundant bubbles. As a result slowly floating minerals are forcibly recovered and railings are effectively separated within this unit. However, cone 1 also reduces the vorticity downstream from it, which reduces the efficiency of railings separation within this part. Therefore, the design of cone 1 should be based on the principles of lessening disturbances to the column unit while strengthening the separation effect of the cyclonic unit. Also, the axial distance between the paired cyclonic structures at the bottom of the column （cone 2） and cone 1 poses tough requirements because of an interaction between separation of the middlings and railings.

Fluent-based numerical simulation of flow centrifugal fan

Testing centrifugal fan flow field by physical laboratory is difficult because the testing system is complex and the workload is heavy, and the results observed by naked-eye deviates far from the actual value. To address this problem, the computational fluid dynamics software FLUENT was applied to establish three-dimensional model of the centrifugal fan. The numeral model was verified by comparing simulation data to experimental data. The pressure centrifugal fan and the speed changes in distribution in centrifugal fan was simulated by computational fluid dynamics soft-ware FLUENT. The simulation results show that the gas flow velocity in the impeller increases with impeller radius increase. Static pressure gradually increases when gas from the fan access is imported through fan impeller leaving fans.

Development of an Emulator for the Plasma Process Control

This work aims at developing an automatic system for the control of the APS （air plasma spraying） plasma process in which some instability phenomena are present. APS is a versatile technique to produce coatings of powder material at high deposition rates. Using this technique, powder particles are injected into a plasma jet, where they are melted and accelerated towards a substrate. The coating microstructures and properties depend strongly on the characteristics of the plasma jet, which can be controlled by the adjustment of the process parameters. However, the imeractions among the spray variables, render optimization and control of this process are quite complex. Understanding relationships between coating properties and process parameters is mandatory to optimize the process technique and the product quality. We are interested in this work to build an on-line control model for the APS process based on the elements of artificial intelligence and to build an emulator that replicates the dynamic behavior of the process as closely as possible.