Don-Hyun Choi
材料科学技术（英文）
A high-carbon steel joint, SK5 (0.84 wt% C), was successfully welded by friction stir welding (FSW), both without and with a gas torch, in order to control the cooling rate during welding. After welding, the weld zone comprised gray and black regions, corresponding to microstructural variation: a martensite structure and a duplex structure of ferrite and cementite, respectively. The volume fraction of the martensite structure and the Vickers hardness in the welds were decreased with the using of the gas torch, which was related with the lower cooling rate.
关键词:
Friction stir welding
李秋材
,
张莉
,
王圣瑞
,
曹长春
,
赵海超
,
李艳平
,
李文章
,
席银
环境化学
doi:10.7524/j.issn.0254-6108.2017.03.2016081501
利用三维荧光光谱和紫外-可见光谱技术,通过室内模拟实验研究了光照对洱海上覆水溶解性有机氮(DON)影响,经平行因子分析法(PARAFAC)和荧光区域积分法(FRI)解析了DON含量、结构组分变化特征,并探讨了其环境学意义.结果表明:(1)未加汞光照条件下,洱海上覆水DON含量随光照时间延长呈波动上升趋势,NH4+与DON含量呈显著负相关(R2=0.94,P＜0.05),即NH4与DON之间存在相互转化,且光照可能促进了NH4向DON的转化;(2)加HgCl2后实验组与对照组SUVA254(1.78、1.85)、A253/A203(0.35、0.34)、E2/ E3(5.85、5.77)及SR(1.03、1.14)均值差别不大,未加HgCl2实验组较对照组SUVA254、A253/A203、Ez/E3值有一定差别,表明光照主要是通过微生物作用,进而影响DON特征,表现为光照增强了DON芳香环取代基结构的复杂程度,并且使得羰基、羧基、羟基和酯基种类有所增多;(3) PARAFAC识别出类蛋白质物质(T峰)和类富里酸物质(A峰)两类组分,表明腐殖质类物质与蛋白质类物质之间可能存在相互转化,且微生物所发挥的作用较为明显.以上结果表明,光照可增强生物活性,进而影响对DON的转化和降解.
关键词:
光照
,
上覆水
,
DON特征
,
平行因子分析
,
荧光区域积分
Physical Review B
An elastic Ising model for CoMnO(6) chain is proposed to explain the ferroelectricity induced by collinear magnetic order in Ca(3)CoMnO(6), and then a mean-field theory with interchain spin interactions based on this model is developed. With inclusion of the dynamics of polarization domains at finite temperature, we address the rationality of our theory by the good agreement of the calculated electric polarization and dielectric susceptibility with the reported data on Ca(3)Co(2-x)Mn(x)O(6) (x approximate to 0.96) [Y. J. Choi, H. T. Yi, S. Lee, Q. Huang, V. Kiryukhin, and S.-W. Cheong, Phys. Rev. Lett. 100, 047601 (2008)], a typical diatomic Ising spin chain system, while the predicted magnetic susceptibility shows some difference from experiment, the reason of which is discussed.
关键词:
calcium compounds;cobalt compounds;dielectric polarisation;ferroelectricity;Ising model;magnetic susceptibility;multiferroics;optical susceptibility;one-dimensional oxides;magnetic-properties;multiferroics;ca3co1+xmn1-xo6
R González
,
J O García
,
M A Barbés
,
et al
钢铁研究学报(英文版)
This research shows, through the analysis of three steels that comply with the EN 10149-2 Euronorm, examples of ultrafine grained (or ultrafine ferrite) ferrous alloys, with ASTM grain sizes close to 14 (2 3 m). These steels are microalloyed with Ti-Nb and have been produced by advanced hot rolling controlled techniques in the factories of ArcelorMittal de Avilés (Asturias, Spain) and are mostly used in automotive and construction applications. By comparison, other techniques to obtain ultrafine grained steels are mentioned, though they have not yet reached the industrial level and are produced in laboratories due to the fact that their mechanical properties (low strain hardening coefficient "n") don't allow cold working operations such as bending, stretching nor drawing.
关键词:
ultrafine steels;metallography;strain hardening;Euronorm
R.B. Song
,
Y.L. Kang
,
J.L. Sun
金属学报(英文版)
The experimental study on the familiar 60Si2Mn and 1Cr18NigTi materials rolled in the semi-solid state was carried out. Experimental results show that the segregation of liquid occurs when the semi-solid slurry is rolled, which influences the microstructure and mechanics performance of workpiece under room temperature. The globular solid particles don't present plastic deformation unless high solid fraction. At the same time, the mechanics property of workpiece is pretty good while the semi-solid slurry of 1Cr18NigTi material is rolled by a pass and no other treatment.
关键词:
semi-solid slurry
,
null
,
null
,
null
,
null
Materials Letters
We have successfully prepared magnetic frustrated compound Mg[Ti-2]O-4 by a novel technique of spark plasma sintering. X-ray diffraction confirms that the sample is single phase and the spinel parameter a = 8.504(7) angstrom at the room temperature. The magnetic susceptibility shows that an abnormal drop is exhibited at about 254 K, indicating a magnetic single formation, and that a paramagnetic susceptibility increase which obeys the Curie Law appears below about 150 K, revealing that the number of Ti3+ ions which don't take part in spin dimer is about 2.6%. The resistivity shows a jump at the temperature of 254 K, in agreement with the transition temperature of measurement of the susceptibility. (c) 2006 Elsevier B.V All rights reserved.
关键词:
frustration;spinel;magnetic susceptibility;SPS;transition;liv2o4;spinel;oxide;ice;system;metal
陈晓辉
,
张晖芬
,
毕开顺
,
金哲史
,
崛池道郎
色谱
doi:10.3321/j.issn:1000-8713.2005.01.019
利用制备高效液相色谱法从日本产杉材(Cryptomeria japonica D.Don)中分离制备倍半萜类化合物.在YWC-Pack C18柱上,以异丙醇-甲醇-正己烷-水(体积比为50:35:10:5)为流动相,流速为5 mL/min,制备了2种倍半萜类化合物,经紫外光谱、红外光谱及核磁、质谱分析,确认它们分别为(-)-cubebol和(+)-2,7(14),10-bisabolatrien-1-ol-4-one.所制备的两个化合物的纯度分别为98.7%和99.1%.
关键词:
制备液相色谱
,
倍半萜类化学成分
,
杉材
赵而团
,
张立新
,
于晴
,
陈文振
材料导报
doi:10.11896/j.issn.1005-023X.2017.04.014
通过对热轧的ZK61镁合金板材试样分别进行不同温度和不同保温时间的退火实验,利用金相显微镜(OM)观察显微组织,对晶粒尺寸进行分析和处理,并建立数学模型,系统研究了轧制ZK61镁合金的晶粒长大行为.研究结果表明,晶粒尺寸随着退火温度的升高与退火时间的延长而粗化,退火温度对晶粒长大的影响比退火时间的影响明显.对于ZK61镁合金在250～450℃温度区间的晶粒长大过程,其晶粒尺寸与加热时间的关系可用Beck方程Dn-Don=kt描述,其中k=koexp[-Qg/(RT)].计算可得晶粒长大指数n为3.5,长大激活能Qg为45 kJ/mol.
关键词:
ZK61镁合金
,
退火
,
晶粒长大
,
Beck方程
高蓓
,
姜德铭
,
杨永坛
色谱
doi:10.3724/SP.J.1123.2016.12028
建立了同位素内标-液相色谱-串联质谱快速测定粮食及其制品中玉米赤霉烯酮(ZON)、雪腐镰刀菌烯醇(NIV)、脱氧雪腐镰刀菌烯醇(DON)及其衍生物3-乙酰基脱氧雪腐镰刀菌烯醇(3-ACDON)和15-乙酰基脱氧雪腐镰刀菌烯醇(15-ACDON)5种真菌毒素的分析方法.以乙腈-水(84:16,v/v)为提取液,采用多功能净化柱净化,同位素内标法定量.5种真菌毒素在各自的线性范围内线性关系良好,相关系数(r.2)均大于0.99,检出限(LOD,S/N=3)为5~20 μg/kg.大麦、小麦、燕麦、玉米等9种代表性粮食及其制品在3个不同添加水平下的加标回收率为84.2%~114.5%,相对标准偏差(RSD)为0.4%~9.9%(n=6).该法操作简单,成本低,准确可靠,灵敏度高,可同时检测粮食及其制品中的5种真菌毒素.
关键词:
液相色谱-串联质谱法
,
同位素内标
,
真菌毒素
,
粮食及其制品
