3D Finite Volume Scheme for Czochralski Crystal Growth

A general three-dimensional model is developed for simulation of the growth process of silicon single crystals by Czochralski technique. The numerical scheme is based on the curvilinear non-orthogonal finite volume discretization. Numerical solutions show that the flow and temperature fields in the melt are asymmetric and unsteady for 8’’ silicon growth. The effects of rotation of crystal on the flow structure are studied. The rotation of crystal forms the Ekman layer in which the temperature gradient along solid/melt surface is small

Energy mechanism for the instability of liquid jets with thermocapillarity

Xu and Davis [J. Fluid Mech. 161, 1-25 (1985)] examined the stability of long axisymmetric liquid jet subjected to an axial temperature gradient, finding capillary, surface-wave, and hydrodynamic modes. They showed that capillary breakup can be retarded or even suppressed for a small Prandtl number (Pr= 1). In the present work, the energy mechanism is carried out for these three kinds of flow instabilities, and the mechanism of suppressing capillary breakup is clarified. When the Reynolds number (R-B) is not large, the work done by the pressure on the free surface (P-S) is the main energy source of the capillary instability. At small Pr and large Bi, the phase difference between the radial velocity and surface deformation increases with R-B, leading to the decrease in P-S, which prevents the occurrence of capillary breakup. Meanwhile, the work done by thermocapillary force becomes the main energy source, making hydrodynamic modes unstable. The perturbation flow fields are displayed, which shows that the temperature fluctuations of three modes differ from each other

Numerical Study on Flow Field and Temperature Distribution in Growth Process of 200 mm Czochralski Silicon Crystals

The melt flow and temperature distribution in a 200 mm silicon Czochralski furnace with a cusp magnetic field was modeled and simulated by using a finite-volume based FLUTRAPP ( Fluid Flow and Transport Phenomena Program) code. The melt flow in the crucible was focused, which is a result of the competition of buoyancy, the centrifugal forces caused by the rotations of the crucible and crystal, the thermocapillary force on the free surfaces and the Lorentz force induced by the cusp magnetic field. The zonal method for radiative heat transfer was used in the growth chamber, which was confined by the crystal surface, melt surface, crucible, heat shield, and pull chamber. It was found that the cusp magnetic field could strength the dominant counter-rotating swirling flow cell in the crucible and reduce the flow oscillation and the pulling-rate fluctuation. The fluctuation of dopant and oxygen concentration in the growing crystal could thus be smoothed

p38MAPK induces apoptosis of glioma cell

目的　研究 p38MAPK基因转染大鼠胶质瘤细胞系C6后对其生物学特性的影响 .方法　利用脂质体介导法将p38MAPK基因导入大鼠胶质瘤细胞系 C6中 ,用免疫细胞化学染色检测其在细胞转染前后的表达情况 ,用 HE染色、流式细胞仪等方法研究其对细胞形态、粘着状况和生长周期的影响 .结果　转染 p CMV5 - p38MAPK质粒组 p38MAPK蛋白表达阳性 ,细胞形态发生变化 ,贴壁性降低 ,出现大量凋亡细胞 .结论　转染 p38MAPK基因可诱导胶质瘤细胞凋亡 【英文摘要】 AIM To study the effect of p38MAPK transfection on the biological characteristics of glioma cell C6. METHODS p38MAPK was transfected into glioma cell C6 by lipofectin. Expression of p38MAPK was detected by immunocytochemistry. HE staining and flow cytometry were adopted to measure the cell morphology, adhesion and cell cycle. RESULTS p38MAPK was expressed in transfected glioma cells, with cell biological characteristics changing and apoptotic cells emerging. CONCLUSION Apoptosis of glioma cell could be ...高等学校骨干教师计划资

Modeling of ammonothermal growth processes of GaN crystal in large-size pressure systems

Gallium nitride (GaN) is a wide-bandgap semiconductor material with a wide array of applications in optoelectronics and electronics. Modeling of the fluid flow and thermal fields is discussed, and simulations of velocity and volumetric-flow-rate profiles in different pressure systems are shown. The nutrient is considered as a porous media bed, and the flow is simulated using the Darcy-Brinkman-Forchheimer model. The resulting governing equations are solved using the finite-volume method. We analyzed the heat and mass transfer behaviors in autoclaves with diameters of 2.22, 4.44, and 10 cm. The effects of baffle design on flow pattern, and heat and mass transfer in different autoclaves are analyzed. For the research-grade autoclave with diameter of 2.22 cm, the constraint for the GaN growth is found to be the growth kinetics and the total area of seed surfaces in the case of baffle opening of 10%. For large-size pressure systems, the concentration profiles change dramatically due to stronger convection at higher Grashof numbers. The volumetric flow rates of the solvent across the baffles are calculated. Since ammonothermal growth experiments are expensive and time consuming, modeling becomes an effective tool for research and optimization of ammonothermal growth processes

Application of Flow-Kinetics Model To the Pvt Growth of Sic Crystals

A 2-D flow-kinetics model for the PVT growth has been used to describe the phenomena of multi-phase flow, mass transfer and kinetics in the growth process of SiC crystals. The model couples the 2-D gas flow calculations and the growth kinetics at the crystal interface. We calculated the axisymmetric flow field and species concentration field as well as growth rate profile by a finite volume-based code. Species transfer in the cavity is dominated by the diffusion at growth pressures of 8-14 kPa. Supersaturation at the crystal interface is less than 1 Pa at growth pressures of 8-14 kPa. (c) 2006 Elsevier B.V. All rights reserved

Hydrothermal Instability Of Thermocapillary Convection In Large-Prandtl-Number Liquid Bridges Under Microgravity

Linear stability analysis was performed to study the mechanism of transition of thermocapillary convection in liquid bridges with liquid volume ratios ranging from 0.4 to 1.2, aspect ratio of 0.75 and Prandtl number of 100. 2-D governing equations were solved to obtain the steady axi-symmetric basic flow and temperature distributions. 3-D perturbation equations were discretized at the collocation grid points using the Chebyshev-collocation method. Eigenvalues and eigenfunctions were obtained by using the Q-R. method. The predicted critical Marangoni numbers and critical frequencies were compared with data from space experiments. The disturbance of the temperature distribution on the free surface causes the onset of oscillatory convection. It is shown that the origin of instability is related to the hydrothermal origin for convections in large-Prandtl-number liquid bridges. (C) 2007 COSPAR. Published by Elsevier Ltd. All rights reserved

p38MAPK induces apoptosis of glioma cell

目的　研究 p38MAPK基因转染大鼠胶质瘤细胞系C6后对其生物学特性的影响 .方法　利用脂质体介导法将p38MAPK基因导入大鼠胶质瘤细胞系 C6中 ,用免疫细胞化学染色检测其在细胞转染前后的表达情况 ,用 HE染色、流式细胞仪等方法研究其对细胞形态、粘着状况和生长周期的影响 .结果　转染 p CMV5 - p38MAPK质粒组 p38MAPK蛋白表达阳性 ,细胞形态发生变化 ,贴壁性降低 ,出现大量凋亡细胞 .结论　转染 p38MAPK基因可诱导胶质瘤细胞凋

AFLP analysis of arbuscular mycorrhizal fungi in roots of Prunus mume

第一作者: 蔡邦平，博士，副研究员。主要研究方向: 园林植物与观赏园艺、植物菌根。电话: 0592--2039576 Email : cbangping@ 163.com 地址: 361003 福建省厦门市思明区虎园路25 号厦门市园林植物园。[中文文摘]为了解决梅根系共生的丛枝菌根(AM)真菌难以应用形态学鉴定的问题,以巢式PCR的AFLP方法研究梅根系AM真菌DNA多态性。试验采集梅花期的根系样品,应用改良CTAB法提取总DNA,经纯化处理后,应用巢式PCR扩增根系AM真菌基因片段,进行AFLP分析。结果表明,18个梅品种的30个根系样品中,仅有8个样品经巢式PCR后获得纯化的DNA片段,占试验样品数的26.7%;8个样品共得到指纹图谱带24条,各样品平均多态性位点数为3.0个,Nei’s基因多样性为0.4097±0.0848,Shannon信息指数为0.5968±0.0955;利用Nei’s遗传相似性系数聚类,梅品种根系内AMF基因组DNA的聚类类别与梅"品种群"这一分类级别无相关性。该试验为植物根系共生AM真菌DNA多态性研究提供了一种简便的技术。[英文文摘]DNA polymorphism of arbuscular mycorrhizal fungi (AMF) was analyzed through the method of DNA amplification by nested PCR based on AFLP marker,in order to solve the difficulty of identifying the species of AMF associated with mei flowers (Prunus mume Sieb.et Zucc.).A total of 30 root samples from 18 mei cultivars were collected in the flowering phase from Wuhan Mei Garden as experimental materials.The results show that the purified DNA can be extracted only from eight root samples that account for 26.7% of total root samples.Totally 24 polymorphic loci were obtained from eight sample roots，averaging 3. 0 loci for each sample.The average genetic identity was 0. 409 7 ±0. 084 8，and the Shannon information index was 0. 596 8 ± 0. 095 5． The clustered groups of AMF DNA by AFLP marker from different cultivars were not identical with cultivar groups of P.mume.The results indicate that the AFLP marker technology is a brief and effective method to study the DNA polymorphism for the AMF in the roots of a plant．教育部科学技术研究重点项目(104034);; 国家自然科学基金项目(30670047);; 厦门市科技计划项目(3502Z20072010、3502Z20112004

赤潮藻经船舶压舱水输入厦门港的风险分析

赤潮是全球性海洋灾害之一,船舶压舱水转运是造成赤潮蔓延的重要途径。本文介绍了40年来厦门港赤潮发生情况和近年来船舶压舱水的活动情况、船舶压舱水赤潮藻监测和检疫对策研究进展;分析和评估了对赤潮藻经船舶压舱水输入厦门港的风险;提出了加大对压舱水研究的力度和对重点赤潮藻进行监测等建议。2003年度厦门市科技项目(编号3502Z20034003