原子捕集－火焰原子吸收光谱法测定人发中的微量铜

本文详细地考查了原子捕集的测定条件及介质的影响，成功地测定了人发中的微量铜。原子捕集法的灵敏度在捕集时间为１ｍｉｎ时为常规法的８．７倍，加标回收率９４．４％－１００．４％。     

消癌平诱导人肺腺癌(ASTC-a-1)细胞内caspase-3活化的荧光光谱分析

采用CCK-8技术检测发现传统中药消癌平（XAP）对人肺腺癌（ASTC-a-1）细胞的增殖活性具有显著的抑制作用。利用共聚焦扫描荧光显微成像、荧光共振能量转移（FRET）及其受体光漂白技术证实了基于FRET技术构建的SCAT3质粒在ASTC-a-1细胞中的稳定表达。将消癌平加入细胞培养液中培育细胞,并在不同的时间检测活细胞内SCAT3的荧光发射光谱,从而监测细胞中caspase-3的活化状态。实验结果表明：(1)消癌平可以有效抑制人肺腺癌（ASTC-a-1）细胞的增殖活性并诱导细胞的死亡,消癌平对细胞的抑制作用具有剂量依赖性。(2)消癌平处理细胞72 h后,细胞内大量的SCAT3被切割,表明细胞内caspase-3的活化水平明显升高。(3)将含消癌平的细胞培养液与细胞共同培养24 h,然后采用没有消癌平的细胞培养液培养细胞48和72 h后,细胞内SCAT3的光谱没有明显改变,表明消癌平作用细胞24 h内没有显著激活细胞内的caspase-3。     

Gradient force evolution of Gaussian beam induced by a phase plate

The evolution of gradient force pattern induced by an annular phase distribution plate is numerically investigated in this paper. The phase plate, which may alter the wavefront phase of incident Gaussian beam with tunable topological charge, consists of two concentric portions, one center circle portion and one annular portion. Numerical simulations show that the proposed plate can induce the tunable gradient force on the particles in the focal region. By adjusting the geometrical parameters or changing the topological charge of the phase-shifting plate, some novel trap patterns may occur, such as triangle shape trap, quadrangle shape trap, pentagon shape trap, hexagon shape trap, and the shapes of optical traps change very considerably. Therefore, the phase plate may be very advantageous for constructing tunable optical traps. The method is more versatile in that it allows precise control of the parameters and has the possibility of generating specific patterns of optical vortices. The gradient force pattern focal of intensity distribution depends on both the annular width and the topological charge.     

First-Passage and Extreme-Value Statistics of a Particle Subject to a Constant Force Plus a Random Force

We consider a particle which moves on the x axis and is subject to a constant force, such as gravity, plus a random force in the form of Gaussian white noise. We analyze the statistics of first arrival at point x ₁ of a particle which starts at x ₀ with velocity v ₀. The probability that the particle has not yet arrived at x ₁ after a time t, the mean time of first arrival, and the velocity distribution at first arrival are all considered. We also study the statistics of the first return of the particle to its starting point. Finally, we point out that the extreme-value statistics of the particle and the first-passage statistics are closely related, and we derive the distribution of the maximum displacement m=max  _t [x(t)].     

Investigation of thermal evolution of nanodomain structures in nonlinear barium sodium niobate crystals

By the 90°elastic light scattering investigation and far field observation in the range of 20-800℃,the relation between behavior of light scattering anomalies and evolution of nanodomain structures in lattice of barium sodium niobate(Ba2NaNb5O15,BSN)crystal was clarified.The correlation between anomalies on the temperature curves of the elastic light scattering intensity and temperature transformations of nanodomains was studied by X-ray and electron microscope methods.Phase transition near 500℃ and movement in field of scattering light could be explained by appearance of a new incommensurate phase.     

Reflection absorption infrared spectroscopy during atomic layer deposition of HfO2 films from tetrakis(ethylmethylamido)hafnium and water

Tetrakis(ethylmethylamido)hafnium and water are commonly used precursors for atomic layer deposition of HfO₂. Using reflection absorption infrared spectroscopy with a buried-metal-layer substrate, we probe surface species present during typical deposition conditions. We observe evidence for thermal decomposition of alkylamido ligands at 320 °C. Additionally, we find that complete saturation of the SiO₂ substrate occurs in the first cycle at ≈100 °C whereas incomplete coverage is apparent even after many cycles at higher temperatures. The use of this technique as an in situ diagnostic useful for process optimization is demonstrated.     

Deposition and electrostatic removal of gaseous organic contaminants on substrate surfaces

The adhesion behavior of di-n-butyl phthalate (DBP) onto different substrates (quartz, glass, and silicon) used as wafer surfaces was studied by using an in situ UV spectrophotometric technique. The results from the closed cell experiments revealed that greatest extent of DBP adhesion occurred on the quartz chip (0.154 μg cm⁻²), followed in the order by the glass (0.054 μg cm⁻²) and silicon (0.039 μg cm⁻²). By means of the in situ spectrophotometric observation, application of an electrical field at 290 V cm⁻¹ in the cell proved to be effective in inducing charging of DBP aerosols, which were consequently attracted towards the electrodes. This method can be applied to wafer storage and transport equipments to prevent wafer contamination from material outgassing representative by DBP.     

原子吸收光谱法间接测定钼精矿中钼的研究

对于钼精矿中钼的测定,标准方法采用钼酸铅重量法,该方法需要将钼酸铅沉淀反复多次洗涤、过滤,以保证沉淀物中夹带的铅离子洗涤完全,再对沉淀物进行灰化、灼烧等多步操作,步骤较繁琐,分析费时,不能快速配合选矿、冶金的科学研究。应用原子吸收光谱法间接测定钼,建立了钼精矿中钼的快速分析方法。钼精矿样品经硝酸、氯酸钾、硫酸加热溶解后,用酚酞和盐酸调节pH值,加入乙酸-乙酸铵缓冲溶液调节pH值至5～7,再加入一定量且过量的铅标准溶液。基于在室温下,钼酸铅为难溶电解质,难溶电解质在一定温度下能否沉淀完全,通常比较离子积Q_c与溶度积常数K_sp的相对大小,当Q_c>K_sp,溶液过饱和,沉淀物完全析出,钼精矿中钼的含量为40～60%,铅的加入量为0.125 0～0.150 0 g,取最小值计算出溶液中钼酸铅的离子积,Q_c＝[Pb2+][MoO2-₄]=2.51×10-5,K_sp＝1.0×10-13,Q_cK_sp,因此钼酸铅沉淀可以完全析出,待钼酸铅沉淀完全后干过滤,用原子吸收光谱法测定滤液中过量的铅离子,用差减法计算得出钼精矿中钼的含量。文中分别考察了乙酸-乙酸铵缓冲溶液的加入量及其浓度、铅标准溶液的加入量、钼酸铅沉淀完全的时间、加热时间以及常见共存离子如W6+,Sn4+和Cu2+等的最大允许量诸多因素对原子吸收光谱法间接测定钼的影响。与钼酸铅重量法相比,该方法省去了对钼酸铅沉淀反复多次的洗涤、灰化以及灼烧等步骤,操作简便易掌握,分析时间缩短一半,并用钼酸铅重量法与本方法进行对照实验,分析结果进行数理统计,得出结论：本方法具有很好的准确度和精密度,可用于选矿、冶金钼精矿样品中钼的快速分析检测。     

悬浮液进样-原子吸收光谱法测定核桃粉中的钙、铁和锌

采用悬浮液进样技术应用于原子吸收光谱法,测定了核桃粉中的钙、铁和锌的含量.将核桃粉悬浮于琼脂胶体中制成悬浮液,直接喷入空气-乙炔火焰,用标准加入法测定,将实验结果与灰化法结果进行了比较,经t检验,在显著性水平a=0.05时两种方法无显著性差异,相对标准偏差≤6.1%,结果吻合较好.该方法简便,快速,灵敏度高,准确性好.     

Thermal stability of alkoxy monolayers grafted on Si(1 1 1)

Direct grafting of organic monolayers on Si is of prime interest in order to give specific properties to a silicon surface. However, for microelectronics applications, this possibility is hampered by the limited stability of the grafted layers. It has been previously established that alkyl layers attached to Si surfaces through Si-C bonds become unstable at 250-300 °C, by desorption of alkenes. Changing the nature of the bonding to the surface might allow one to circumvent this desorption pathway and increase the layer stability. In our work, decanol and decyl aldehyde are reacted with the Si(1 1 1)-H surface at ∼100 °C during 20 h in order to obtain alkoxy monolayers. FTIR measurements performed in ATR geometry show that the grafted molecule surface coverage is on the order of 33% after reaction with decanol and 50% after reaction with decyl aldehyde. Characterization by AFM essentially reveals that the morphology of the grafted surfaces is unaffected as compared to that of Si-H surfaces. However, the edges of the terraces at alcohol-grafted surfaces exhibit some pitting, probably due to the presence of water in the grafting liquid. Thermal stability studies show that alkoxy chains progressively disappear from the Si surface between 200 and 400 °C. From the CH₂/CH₃ ratio in the CH region (2760-3070 cm⁻¹), it appears that the chains undergo progressive dissociation by C-C bond breaking before their complete disappearance from the surface. Therefore, the thermal behaviour of alkoxy monolayers appears quite distinct from that of alkyl monolayers that tend to leave the surface in a much narrower temperature range (250-350 °C), essentially via breaking of the Si-C bonds.