Temperature dependence of surface and structure properties of ZnCdO film

Zn1-xCdx O films are grown on c-sapphire substrates by laser molecular beam epitaxy(LMBE) at different temperatures. Their crystallographic structures, compositions, surface electronic structures are investigated. The a-axis lattice constant of Zn0.95Cd0.05 O is 3.20. Moreover, the epitaxial relationship shows a 30°-in-plane rotation of the film with respect to the c-sapphire substrate. When the substrate temperatures arrives at 500℃, the in situ reflection high-energy electron diffraction(RHEED) pattern of Zn Cd O film shows sharp streaky pattern. The maximum Cd content of Zn Cd O film grown at low substrate temperatures increases up to about 29.6 at.%, which is close to that of the ceramic target. In situ ultraviolet photoelectron spectroscopy(UPS) measurements demonstrate that Zn Cd O film exhibits intense peaks at 4.7 e V and 10.7 e V below the Fermi level, which are assigned to the O 2p and Zn 3p states. Energetic distance between Zn 3d and Cd 4d is 0.60 e V. Above 470 nm, the thin film shows excellent optical transmission.     

顶空固相微萃取-气相色谱-质谱法测定地表水中硝基氯苯

硝基氯苯在染料、制药和农药等工业中的大量使用可能污染到地表水。硝基氯苯作为全国重点城市饮用水源地水每月必测项目之一,分析标准需用到有机萃取溶剂乙酸乙酯和苯,这些有机萃取试剂的使用对分析人员的健康和环境都是有害的,同时方法相对繁琐。而固相微萃取、固相萃取、顶空和吹扫捕集等相对环保的前处理方法适合水和废水中硝基氯苯的测定。固相微萃取中,顶空萃取方式和浸入式相比,具有不用考虑样品     

顶空固相微萃取-气相色谱-质谱法同时测定饮用水源水中24种VOCs

建立了同时测定饮用水源水中24种挥发性有机物(VOCs)的顶空固相微萃取-气相色谱-质谱法.用75 μm CarboxenTM-Polydimethylsiloxane(CAR-PDMS)固相微萃取柱顶空萃取水样中的VOCs,VOCs用气相色谱-质谱联用仪检测,采用内标法定量.对萃取柱涂层、样品盐度、萃取温度和萃取时间等样品前处理条件进行了优化,VOCs的检出限在0.03～0.31 μg/L之间,线性相关系数r＞0.996(二氯甲烷和三氯甲烷除外).对饮用水源水实际水样0.50μg/L和1.00 μg/L两个加标浓度水平的回收率进行了测定,三氯甲烷回收率均值分别为104％和142％,其余VOCs回收率分别为90.0％～120％和88.0％～110％,除二氯甲烷和三氯甲烷外,其余VOCs测定结果的相对标准偏差均小于15.0％(n=6).该方法适用于饮用水源水中挥发性有机物的监测分析.     

对数似然图像分割的快速主动轮廓跟踪算法

针对跟踪目标尺度变化问题,提出了基于灰度对数似然图像分割的快速主动轮廓跟踪算法。改进的主动轮廓跟踪算法将根据以目标与背景的颜色差异而建立的对数似然图对图像进行阈值分割和数学形态学处理,再将Kalman滤波器结合到主动轮廓跟踪算法进行目标跟踪。改进的主动轮廓跟踪算法对目标分割准确,轮廓特征显著,跟踪效果稳定,算法能很好地适应跟踪目标尺度变化。通过Kalman滤波器对目标位置点的预测减少了主动轮廓跟踪算法收敛的迭代次数,使算法的运算效率提高了33%左右。     

用扩散蒙特卡罗方法研究BH2, B(OH)2, BCl2和BCl的键离解能

采用扩散蒙特卡罗(DMC)方法计算了BH₂, B(OH)₂, BCl₂和BCl的HB-H和HOB-OH的键离解能, 同时也研究了轨道选择和Backflow变换对DMC计算结果的影响． 在Slater-Jastrow DMC(SJ-DMC)计算方法中,当采用B3PW91轨道时得到的HB-H和HOB-OH键离解能分别是359.1±0.12和98.2±0.12 kJ/mol;用B3LYP SJ-DMC计算键离解能得到了与用B3PW91 SJ-DMC方法类似的结果．通过BF-DMC(即在DMC中引入backflow修正)计算得到的HB?H键离解能为369.6±0.12 kJ/mol,也得到了更加接近实验值的HOB-OH键离解能为446.0±1.84 kJ/mol．由DMC的计算结果可以断定HB?H的键离解能的实验值为375.8 kJ/mol．另外还给出了BCl2和BCl的键离解能的计算结果.     

米根霉胞内氨基酸的高效液相色谱测定及其代谢途径分析

建立了米根霉胞内代谢物提取方法定量评价体系,用100％甲醇作为提取剂获得对米根霉胞内能荷物质最佳的提取效果.用HPLC法建立了米根霉产富马酸体系胞内18种氨基酸的含量测定方法.采用异硫氰酸苯酯( PITC)作为柱前衍生化试剂,所有氨基酸在28 min内洗脱完毕.以Sepax AA柱(250 nn×4.6 mm,5μm)为分析柱,流速1.0 mL/min,检测波长254 nm,以0.1 mol/L醋酸钠(pH 6.5)-乙腈(93∶7,V/V)为流动相A,乙腈-水( 80∶ 20,V/V)为流动相B,梯度洗脱.18种氨基酸在1.87～45.3 mg/L范围内线性关系良好,相关系数大于0.991;加标回收率在96.3％～102.7％之间;相对标准偏差在1.6％～2.9％之间.运用本方法测定不同发酵时间米根霉胞内氨基酸的含量,得到其在发酵过程中的变化趋势,并结合氨基酸代谢途径分析了该发酵条件下富马酸产量偏低的原因.     

Ar adsorptions on Al （111） and Ir （111） surfaces： a first-principles study

We investigate the adsorptions of Ar on Al (111) and Ir (111) surfaces at the four high symmetry sites,i.e.,top,bridge,fcc-and hcp-hollow sites at the coverage of 0.25 monolayer (ML) using the density functional theory within the generalized gradient approximation of Perdew,Burke and Ernzerhof functions.The geometric structures,the binding energies,the electronic properties of argon atoms adsorbed on Al (111) and Ir (111) surfaces,the difference in electron density between on the Al (111) surface and on the Ir (111) surface and the total density of states are calculated.Our studies indicate that the most stable adsorption site of Ar on the Al (111) surface is found to be the fcc-hollow site for the (2 × 2) structure.The corresponding binding energy of an argon atom at this site is 0.538 eV/Ar atom at a coverage of 0.25 ML.For the Ar adsorption on Ir (111) surface at the same coverage,the most favourable site is the hcp-hollow site,with a corresponding binding energy of 0.493 eV.The total density of states (TDOS) is analysed for Ar adsorption on Al (111) surface and it is concluded that the adsorption behaviour is dominated by the interaction between 3s,3p orbits of Ar atom and the 3p orbit of the base Al metal and the formation of sp hybrid orbital.For Ar adsorption on Ir (111) surface,the conclusion is that the main interaction in the process of Ar adsorption on Ir (111) surface comes from the 3s and 3p orbits of argon atom and 5d orbit of Ir atom.     

基于Mathematica的弹簧摆内共振现象研究

利用Mathematica软件模拟弹簧摆的内共振现象,得出了弹簧摆的运动轨迹、振动曲线和能量曲线,计算机模拟的结果与实验结果相吻合.     

原料奶在HPLC-MS负离子模式下的指纹图谱研究

采用高效液相色谱质谱联用技术,在负离子扫描模式下建立了原料奶的乙腈提取成分的指纹图谱。采用乙腈和0.1％的乙酸为流动相进行二元梯度洗脱,柱温30℃,分析时间为85 min。确定了11个共有峰,以7号峰为参照物,通过相对峰面积和相对保留时间进行了方法学考察。结果表明,本方法具有良好的重现性,各指纹峰相对保留时间的RSD<0.79％,相对峰面积的RSD<2.84％。在原料奶指纹图谱基础上,选取有代表性有害物如防腐剂苯甲酸等进行了标准添加,建立了添加图谱,对沈阳地区超市的50个纯牛奶样品进行了筛查,取得初步应用结果。     

小肠电离辐射损伤研究进展

肠道的电离辐射损伤是腹部及盆腔肿瘤放射治疗过程中的剂量限制因素。综述了小肠电离辐射损伤的临床症状、 小肠上皮及粘膜下层基质改变、 信号分子表达变化、 组织学变化和超微结构变化。简介了中国科学院近代物理研究所重离子束辐射生物医学重点实验室正在进行的有关小肠重离子辐射损伤及防护方面的研究工作。Intestinal ionising radiation injuries are a dose limiting factor in the course of radiotherapy of abdominal and pelvic malignancies. In this paper it is reviewed that ionizing radiation injuries of small intestine, including clinical symptoms, epithelium and submucosa changes, signal molecular expression changes, histological and ultrastructure changes. The ongoing works of our laboratory on subjects of intestinal injuries induced by heavy ions and protection against these injuries are also presented.