L.F. Zhang
,
K.K. Cai
,
Y. Qu and Y.S. Shen Postdoctoral Fellow of Japan Science Promotion Society Taniguchi Lab.
,
Department of Metallurgy
,
Graduate School of Engineering
,
Tohoku University
,
Sendai980-8579
,
Japan School of Metallurgy
,
University of Science and Technology Beijing
,
Beijing 100083
,
China
金属学报(英文版)
In the present paper, based on the two-phase model (Eulerian model), the two dimensional fluid flow liz air-stirred water systems is simulated, and the effect of interphase lift force on the fluid flow is specially discussed. In the Eulerian two-phase model, gas and liquid phase are considered to be two different continuous fluids interacting with each other through the finite inter-phase areas. The exchange between the phases is represented by source terms in conversation equations. Turbulence is assumed to be a property of the liquid phase, k - ε model is used to describe the behavior of the liquid phase. The dispersion of phases due to turbulence is represented by introducing a diffusion term in mass consecrvation equation. The contribution of bubble movement to the turbulent energy and its dissipation rate is taken into accounted by adding extra volumetric source terms to the equations of turbulent enemy and its dissipation rate. The comparison between the mathematical simulation and experiment data indicates that the interphase lift force has a big effect on the flow behavior, and considering both drug force and lift force as interphase forces is important to accurately simulate the gas-water two-phase fluid flow in air-stirred systems. The interphase lift force makes bubbles move away from the centerline, the gas concentration is decreased near the centerline, and increased near the wall. The lift force is smaller than drug force at the same place, especially far away from the centerline.
关键词:
two-phase Eulerian model
,
null
,
null
,
null
刘春艳
,
姜申德
应用化学
doi:10.3724/SP.J.1095.2011.00686
设计合成了5种新型正电子发射断层显像剂O-(2-[18F]氟乙基)-L-酪氨酸的前体化合物:N-叔丁氧羰基-O-(2-甲磺酰/对硝基苯磺酰)-氧乙基-L-酪氨酸甲酯(9a,11a)和N-叔丁氧羰基-O-(2-甲磺酰/对甲苯磺酰/对硝基苯磺酰)-氧乙基-L-酪氨酸叔丁酯(9b,10b,11b).这些化合物以L-酪氨酸为原料,先与甲醇发生酯化反应或与乙酸叔丁酯进行酯交换,再用叔丁氧羰基保护氨基,最后以碳酸钾为碱、18-冠-6为相转移催化剂与乙二醇的磺酸酯在丙酮溶液中加热回流形成目标化合物,总收率为30％ ～67％.
关键词:
正电子发射断层显像
,
L-酪氨酸
,
O-(2-[18F]氟乙基)-L-酪氨酸前体,正电子发射断层成像
Journal of Materials Research
The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.
关键词:
room-temperature
冶金分析
提出了离子色谱法检测电镀液中F-和Cl-的方法.根据高沸点酸置换低沸点酸,用硫酸作为蒸馏剂,在一定的温度下,将F-和Cl-一起蒸馏出进行分离和富集,消除了电镀液中大量共存离子的干扰和对色谱柱的污染.使用IonPacASl4A作为色谱柱,在合适的色谱条件下,F-和Cl-的色谱峰能很好地分离,其检出限分别为0.84 μg/L和0.37 μg/L,相对标准偏差F-小于7.3%,Cl-小于4.2%(n=10),加标回收率F-在91%～107%、Cl-在95%～105%之间(n=10),电镀液中共存离子对F-和Cl-的测定无干扰.方法用于电镀液中F-和Cl-的同时测定,具有很好的可行性和实用性.
关键词:
F-
,
Cl-
,
离子色谱
,
蒸馏法
,
电镀液
李谋成
,
曾潮流
,
林海潮
,
曹楚南
金属学报
对含氟离子(F-)稀盐酸介质中316不锈钢的钝化行为进行了研究.结果表明,自然腐蚀电位下316不锈钢在含F-稀盐酸溶液中能够钝化;低浓度F-对不锈钢钝化性能的影响很小,但较高浓度的F-(≥0.01 mol/L)能够显著降低钝化性能;阳极极化过程中不锈钢表面能形成含F-的富Cr钝化膜.提出了F-离子破坏钝化膜的加速反应机理.
关键词:
不锈钢
,
null
,
null
,
null
阳建红
,
董进辉
,
李海斌
,
石强
,
郭明映
复合材料学报
在60℃、80℃相对湿度90%环境条件下对F-12纤维进行了湿热老化实验,研究了长时间老化时纤维吸湿规律.通过ATR-FTIR光谱分析了湿热老化后水对F-12纤维化学结构的影响以及水在纤维中可能存在的方式,探讨了吸湿机制,实验研究了纤维单丝拉伸强度的变化,并采用SEM观察了纤维表面及拉伸断口形貌.结果表明:F-12纤维长时间的吸湿属于2阶段吸湿,吸湿初期符合Fick第二定律,后期偏离,吸湿2500 h后仍没达到平衡;水分子对F-12纤维的化学结构没有造成明显的破坏,老化2500 h后F-12纤维表面变得粗糙,出现了一些沟槽,老化后期断口呈现出脆性与原纤化复合的特征;拉伸断裂强度并非持续减小,而是在起伏波动中减小.
关键词:
F-12纤维
,
吸湿规律
,
ATR-FTIR
,
SEM
,
吸湿机制
,
拉伸强度
杨武
,
陈淼
,
康经武
,
欧庆瑜
,
康敬万
,
高锦章
冶金分析
doi:10.3969/j.issn.1000-7571.1999.05.013
对f-f跃迁光谱在分析化学中的应用进展进行了简要的总结,详细地介绍了根据超灵敏跃迁强度变化规律测定溶液中镧系配合物的组成、形成常数及测定混合稀土中单一稀土的原理和方法.
关键词:
f-f跃迁光谱
,
镧系元素配合物
,
组成测定
,
形成常数
,
综述
刘勤
,
裔式珙
材料研究学报
在250℃以■=0.025min~(-1)测到的Zn-5%Al 合金的超塑性m-δ曲线均属式。w_0/l_0值加大使m_0,m_L 和δ_F 值增大,但对δ_L 和m_F 值无大影响。试样厚度的加大(由1增大到2mm)仅使δ_L 和δ_F 值增大,考虑w_0/l_0比值的影响,C_3~((m_0-m_L))-(m_L=m_(mas))型C.L.m-δ方程式规划为:或其中,m′_0(W_0/l_0)=m_0,m′_0>m_0;m′_L(w_0/l_0)=m_L,m′_L>m。w_0/l_0=0.15—0.39。当w_O/l_0=1时,缺口效应消失,δ(或δ_F)值为最大。
关键词:
Zn-5%Al合金
,
mechanics of superplasticity
,
C.L.m-δequation
