吖啶橙与ctDNA相互作用机理的光谱法研究

应用光谱法研究了三环杂芳香类染料吖啶橙(AO)与DNA的相互作用,探讨了以AO为探针与小牛胸腺DNA(ctDNA)的作用机理。在pH2.00的Tris-HCl缓冲溶液中,AO在DNA的表面聚集作用导致体系的共振光散射(RLS)增强,在339nm处出现了新增强的RLS峰;通过紫外-可见吸收光谱观察,当DNA与AO的质量比超过0.166后,AO与DNA的作用方式经历了由嵌入到聚集的改变;进一步研究用荧光法作Scatchard图得出AO与DNA的作用方式为嵌入和静电的混合作用模式:每个核苷酸上的成键位点数n和每一位点的结合常数K均随AO浓度改变而发生了变化。此外,还研究了阴离子表面活性剂的协同作用等。     

孔雀石绿-锌(Ⅱ)-牛血清白蛋白的共振光散射及其分析应用

基于牛血清白蛋白(BSA)使孔雀石绿(MG)-锌(Ⅱ)配合物体系的共振光散射光谱(RLS)信号增强,建立了一种测定痕量蛋白质的新方法。探讨了pH、MG浓度、金属离子浓度、共存物质等因素对共振光散射强度的影响。在优化实验条件下,RLS强度与BSA浓度的线性范围为0.1—25μg/mL,检出限0.06μg/mL,运用该方法对合成样品加标回收测定,结果满意。     

碳纳米管/寡聚胸腺嘧啶复合体系与汞离子作用的光谱研究

利用寡聚胸腺嘧啶核苷酸(PolyT)与碳纳米管(CNTs)之间的自发非共价修饰作用形成稳定的CNTs/PolyT纳米复合体系,采用共振光散射(RLS)和紫外-可见吸收光谱考察了该复合体系与汞离子的相互作用.实验结果表明,水相中单链PolyT能与CNTs形成稳定而均匀的分散体系,而单链Po1yT极易捕获汞离子生成特异性的...     

核酸适配体纳米金共振散射光谱检测血清中钾离子

在pH7.0的Na2HPO4-NaH2PO4缓冲溶液中,纳米金与适配体(aptamer)结合形成较稳定的aptamer-Au复合物,且不被NaCl聚集。在85℃水浴中,K+与aptamer作用后折叠形成稳定的G-四分体结构复合物且释放出纳米金。在高浓度盐作用下,纳米金聚集成较大粒径的纳米金颗粒,导致体系563nm处的共振散射强度增大,其平均粒径为120nm。文章研究了K+ -随机单链DNA1(ssDNA1)-纳米金、K+ -ssD-NA2-纳米金和K+ -aptamer-纳米金体系的共振散射光谱特性,并用圆二色光谱技术证明了核酸适配体结构的变化。考察了pH、NaCl浓度、aptamer浓度、纳米金用量以及Cu2+、Mg2+、Pb2+、Ca2+、Al3+、Zn2+Fe3+等常见重金属离子等对测定K+的影响,结果显示这些离子不干扰测定,该法具有较好的选择性。在选定条件下,K+浓度在0.67～3350μmol·L-1范围与共振散射峰值ΔI呈良好的线性关系,回归方程、相关系数、检出限分别为ΔI=0.167c-0.7,0.9932,0.3μmol·L-1 K+。该法用于血清样品分析,结果与离子选择电极法一致。     

硫离子修饰的金纳米棒用于汞离子检测

表面修饰硫离子的金纳米棒可与汞发生相互作用,导致体系的共振光散射（RLS）和紫外-可见吸收光谱发生变化。利用这种特殊的选择性结合反应建立了一种采用RLS技术定量检测水溶液中汞离子的新方法。在优化的实验条件下,汞离子分析测定的线性范围为0.1—10.0μm ol.L^-1,检出限为0.096μm o.lL^-1。     

表面活性剂对气-液界面纳米颗粒吸附规律的影响

通过测定及分析纳米颗粒和表面活性剂-纳米颗粒复配体系在自由吸附过程与动态收缩过程中表面张力的变化,总结了纳米颗粒在气-液界面的吸附排布规律以及表面活性剂对其吸附规律的影响.实验结果表明,自由吸附过程中,随矿化度增加、阳离子活性剂浓度增加,平衡表面张力降低,这与颗粒吸附密度增加及颗粒润湿性改变有关.浓度低于临界胶束浓度(CMC)时,阳离子活性剂体系与混合体系的表面张力差异证明了阳离子活性剂可以通过静电作用吸附于纳米颗粒表面,进而部分溶解于水相;而阴离子活性剂与纳米颗粒相互作用力较弱,对表面张力影响较小.纳米颗粒体系在液滴收缩过程中,表面张力从自由吸附平衡态进一步降低大约9 m N/m,说明自由吸附过程中纳米颗粒不能达到紧密排布;同时表面张力呈现为缓慢降低、快速降低和达到平衡三部分,表面压缩模量可达70 m N/m,满足了液膜Gibbs稳定准则,这将有助于提高泡沫或者乳液稳定性.纳米颗粒-表面活性剂体系在液滴收缩过程中表面张力降低值随活性剂浓度增加而减小;表面压缩模量由高到低依次为:纳米颗粒>阳离子活性剂-纳米颗粒>阴离子-纳米颗粒>表面活性剂.     

基于与桑色素相互作用共振光散射法测定盐酸巴马汀

在pH 为4.6的HAc-NaAc介质中,盐酸巴马汀与桑色素通过静电引力发生反应,得到具有疏水性的离子缔合物,致使体系在308 nm处的共振光散射信号显著增强。研究表明,体系增强的共振光散射信号强度与盐酸巴马汀的浓度在0.08～1.0 μmol·L-1之间具有良好的线性关系,检测限为8.0 nmol·L-1。由此建立了用于盐酸巴马汀检测的共振光散射分析方法。研究了体系的散射光谱和吸收光谱,通过扫描电镜和动态光散射考察离子缔合物的聚集情况并研究了体系的反应机理,研究了酸度及离子强度对体系的影响,最终实验选择pH 4.6的HAc-NaAc缓冲,不加NaCl控制体系离子强度的情况下信号最佳。探讨了体系的稳定性,结果显示本反应体系反应迅速,5min内散射强度即可达到最大值并至少能稳定120 min。考察了可能存在的共存物质的影响,结果发现常见的金属离子,无机阴离子,部分糖类及氨基酸不影响对盐酸巴马汀的检测。该方法具有简单,快速,灵敏度高的优点。该法成功用于实际药片和胶囊中盐酸巴马汀含量的测定,RSD≤3.3%。     

共振光散射及荧光光谱法研究冰片对DNA的抑病机制

首次在分子水平上研究了冰片与DNA的相互作用,以期发现冰片的抗病机理.通过共振光散射技术、荧光光谱法以及粘度法,确定了冰片与DNA的作用方式为部分嵌入式.在pH7.40,温度37 ℃,离子强度低于0.01 mol/L条件下,冰片与DNA发生反应,导致410nm和470nm处的共振光散射增强,且反应体系至少在12h内保持稳定.通过改变反应体系的离子强度和pH值,发现二者的反应对离子强度及反应体系的pH值具有较强的敏感性.同时通过粘度实验和EB(溴化乙锭)荧光探针竞争实验发现:冰片的加入使DNA双螺旋发生扭结,导致DNA的粘度减少;冰片使EB-DNA体系的荧光强度降低.     

铝试剂的共振散射光谱研究

研究了铝试剂 (ATA)的共振散射光谱、吸收光谱和荧光光谱。在pH3 7～ 1 1 0的溶液中 ,ATA的共振光散射 (RLS)信号很弱 ;当pH <3 7时 ,RLS随pH值减小而增强 ,pH 2 7时达到最大。RLS信号增强的原因是ATA由带负电荷的型体转变为中性分子并聚集形成超分子聚合体。RLS光谱图中 2 60和 340nm出现两个散射峰 ,30 0nm处为一峰谷 ,而在吸收光谱图中 30 0nm处为一吸收峰 ,由此可知ATA的RLS光谱与其吸收光谱有关 ,RLS信号强度随波长的变化不符合瑞利散射定律。ATA的荧光激发光谱和发射光谱不重叠 ,说明RLS光谱中没有共振荧光成分。在实验条件一定时 ,RLS强度与ATA浓度有关 ,但不是严格的线性关系。     

基于AgI2-缔合微粒共振散射效应测定阳离子表面活性剂

在pH 3.5 NaAc-HCl介质中,Ag 与过量的I-形成可溶性AgOI2-;当十六烷基三甲基溴化铵(CT-MAB)与AgI2-共存时形成粒径为700 nm的(CTMA-AgI2)n缔合微粒,在360 nm处产生一个共振散射峰,在470 m处产生一同步散射峰.CTMAB浓度cCTMAB在2.0～50.0×10-7mol·L-1范围内与散射光强度I360nm呈线性关系,回归方程为I360nm=2.03×107 cCTMAB 0.48,相关系数r为0.998 5,检出限为8.0×10-8mol·L-1.据此建立了一个测定阳离子表面活性剂含量的共振散射光谱法,用于水样分析,结果满意.共振散射光谱和激光散射研究表明,CTMAB 与AgI2-可通过静电力形成疏水性的CTMA-AgI2缔合物分子,该缔合物分子自动聚集形成稳定的(CTMA-AgI2)n缔合微粒.由于该缔合微粒仅在360 nm处产生共振散射效应,故体系呈乳白色.     

Anomalous temperature-dependent behaviors of electroluminescence phenomena in disordered ITO/PEDOT/PF/Ca/Al polymer light-emitting diodes

In this study we systematically investigated the anomalous Berthelot-type optical property dependence of the electroluminescence (EL) that occurs in polymer light-emitting diode (PLED) structures. Devices were operated at 0.1 and 0.5 mA over a temperature range from 300 to 20 K. Initially, the emission intensity increased as the temperature decreased, until a maximum was reached at the turning-point temperature T_t. After this, the intensity decreased with further decrease of temperature down to 20 K. A smaller reduction in intensity was exhibited by the device with 0.5 mA, a larger one exhibited by the device with 0.1 mA. The strong electron-electron scattering arising from high excitation, high microcrystalline randomization and high hopping frequency led to the corresponding dominance of the Berthelot-type process by a large T_t. It can be seen in the Arrhenius plot of the integrated EL intensity that a smaller activation energy can be expected to facilitate the redistribution of the thermal carriers, overcoming the energy barrier and the large degradation of luminescence. This results in not only better than carrier confinement, but also enhances the quantum efficiency of PLED structures requiring lower excitation.     

Production of A20and ω1 (1675) in the reaction π−p → π+π−π0n at 12 and 15 GeV/c

Data on the reaction π^?p → π⁺π^?π⁰ have been taken at 12 and 15 GeV/c with the CERN Omega multiparticle spectrometer. In a 3-pion partial-wave analysis strong production of $\text{A}{}_2{}^0\text{(1310)}\text{and}\text{ω}{}^1\text{(1675)}$ is observed. Total and differential cross sections are determined and density matrix elements presented as a function of t in the t- and s-channel frames. The energy dependence of A₂⁰ production is studied, and a comparison of $\text{ω(780),}\text{A}{}_2{}^0\text{(1310)}\text{and}\text{ω}{}^1\text{(1675)}$ production is made.     

Resonant tunneling in GaAs/AlxGa1−xAs superlattices with aperiodic potential profiles

Using the exact Airy function formalism and the transfer-matrix technique, we have numerically investigated in this paper the effect of intentional correlations in spatial disorder on transmission properties of one-dimensional superlattices. Such systems consist of two different structures randomly distributed along the growth direction, with the additional constraint that barriers (wells) of one kind always appear in triply. It is shown that the intentional correlations in disorder and superlattices structural parameters are responsible to obtain resonant tunneling in aperiodic structure.     

铁电磁体Pb(Fe1/2Nb1/2)O3的磁电性能研究

对铁电磁体Pb(Fe_1/2Nb_1/2)O₃单晶样品中的 介电和磁性能进行了研究. 认为在其反铁磁相变点观察到的介电常数和损耗的异常来自于自发极化序和自旋序的相互作用 引起的磁电耦合. 磁矩与温度的关系曲线在Nel点以下的低温段呈上升趋势，测得的磁滞 回线证明有弱铁磁性出现. 对铁电磁体磁电相互作用的Monte Carlo模拟得到与实验类似的 结果. 关键词： 铁电磁体 1/2Nb_1/2)O₃')" href="#">Pb(Fe_1/2Nb_1/2)O₃ 磁电耦合 Monte Carlo模拟     

High-resolution electron microscopy study of Ni81Fe19 film with Co33Cr67 buffer layer

The anisotropic magnetoresistance (AMR) in permalloy Ni₈₁Fe₁₉ film deposited on a 1.2 nm Co₃₃Cr₆₇ buffer layer was significantly enhanced. The high-resolution electron microscopy was used to study the microstructure of Ni₈₁Fe₁₉ film with and without Co₃₃Cr₆₇ buffer layer. It was found that Co₃₃Cr₆₇ buffer layer can induce good (1 1 1) texture, while without Co₃₃Cr₆₇ buffer layer, Ni₈₁Fe₁₉ film show randomly oriented grain structure. The Δρ/ρ enhancement is attributed to the decrease in the resistivity ρ of the Ni₈₁Fe₁₉ film due to the formation of the large (1 1 1) textured grains in Ni₈₁Fe₁₉ film with Co₃₃Cr₆₇ buffer layer. However, the surface roughness of substrate may limit the (1 1 1) textured grain size and induce additional grain boundaries in Ni₈₁Fe₁₉ film with Co₃₃Cr₆₇ buffer layer, limit the enhancement of the AMR effect.     

XPS and XRD investigation of Co/Pd/TiO2 catalysts by different preparation methods

In the article, the Co/Pd/TiO₂, Co/TiO₂ and Pd/TiO₂ catalysts prepared by the impregnation and sol–gel method are studied by using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The result shows that Co²⁺ and metal Pd may act as the active center for the direct synthesis of acetic acid from CH₄ and CO₂ by a two-step reaction sequence. When the catalysts are prepared by the sol–gel, Co²⁺ can enter the crystal lattice of the TiO₂, causing the phase transition from anatase to rutile at lower temperature, but existence of Pd²⁺ can prevent from the phase transition. When the catalysts are prepared by the impregnation, the phase transition is inhibited not only Co²⁺ but also Pd²⁺.     

(Lu,Y)2SiO5∶Ce3+与SrSO4∶Dy3+材料低温热释光及其测试仪器的研究

为了分析材料在低温下的陷阱能级,获得更多有关缺陷结构的信息,研制了一套由STM32微控制器为核心的低温热释光发光谱测量系统。设计了低温样品室,采用液氮冷却样品;STM32通过控制加热电流,实现样品以恒定速率升温,从而获得低温热释光发光曲线或三维热释光谱。温度测量范围为85~400 K,升温速率范围为0.1~10 K/s。设计了由STM32控制X射线及紫外光源的驱动电路,用于样品的激发。采用高灵敏度CCD实现对三维热释光谱的测量,采用单光子计数器获取二维热释光发光曲线。利用该系统测试了（Lu,Y）₂SiO₅:Ce³⁺（LYSO:Ce³⁺）单晶闪烁体与SrSO₄:Dy³⁺粉末样品的热释光谱及辐射发光光谱。观察到LYSO:Ce³⁺在108,200,380 K左右的热释光峰,发光波长位于390~450 nm之间,是明显的宽带峰。在低温下由于基质的自陷激子（STE）发射所形成的发射峰在166 K时发生猝灭。在309 K时,Ce³⁺发射峰展宽为单一发射峰;SrSO₄:Dy³⁺发光峰温度为178,385 K,发光波长由Dy³⁺离子的能级跃迁决定,在480,575,660,750 nm处呈现窄带发光峰。结果表明,系统人机交互界面友好,实验数据可靠,智能化程度高,操作简单。     

Er3+/Yb3+共掺TeO2-Li2O-B2O3-GeO2玻璃系统的光谱性质和热稳定性研究

制备了Er³⁺/Yb³⁺共掺的70TeO₂-5Li₂O-(25-x)B₂O₃-xGeO₂（x=0,5,10,15,20 mol%）系列玻璃, 研究了玻璃的热稳定性能, 测试了玻璃的吸收光谱、荧光光谱以及Er3+离子4I13/2能级荧光寿命, 并根据McCumber理论计算了Er³⁺离子4I13/2→4I15/2跃迁的受激发射截面. 结果表明：随着GeO₂含量的增加, 玻璃的热稳定性逐渐提高, 荧光谱线半高宽（FWHM）保持在70 nm左右, 而荧光强度和Er3+离子4I13/2能级荧光寿命逐渐提高, 研究表明这种玻璃系统是一种具有应用潜能的宽带光纤放大器用的基质材料.     

Mixed disorder in GaAs/AlxGa1−xAs superlattices and its effect on the range of wavelength infrared lasers

By introducing a mixed disorder on GaAs/Al_xGa_1−xAs superlattices, a wide range of infrared (15–248 μm) was achieved. The studied systems consist of two different structures randomly distributed along the growth direction, with the additional constraint that the structure with height barrier V₂ and thickness d_b2 appear only by doublet or triplet. The exact Airy – function formalism combined with a transfer matrix technique was used for evaluating the transmission probability and laser wavelength. The analysis of the proposed model shows that the far infrared wavelength is obtained when the aluminum mole fraction increase and mixed disorder is introduced by trimer.     

Structural and magnetic studies of CuO-TeO2 and CuO-TeO2-B2O3 glasses

The glass systems xCuO ^. (1- x)TeO₂ and xCuO ^. (1- x)[75TeO₂ ^. 25B₂O₃] with 0 < x ? 50 mol% were investigated by means of X-ray diffraction, electron paramagnetic resonance (EPR) and a.c. magnetic susceptibility ( ) measurements, the principal aim of the investigation being the study of the structural modifications in the tellurite glasses introduced by the addition of boron oxide. In the case of first glass system, i.e. without B₂O₃, EPR spectra of Cu²⁺ ions undergo changes with the increasing concentration of CuO. At very low concentrations, spectra are due to isolated Cu²⁺ ions in axially distorted octahedral sites. The EPR signal for samples with 3 ? x ? 20 mol% can be explained as being the superposition of two EPR absorptions, one showing the hyperfine structure typical for isolated Cu²⁺ ions and the other consisting of a symmetric line typical for clustered ions. The broadening of the absorption band is due to dipolar as well exchange interaction. The susceptibility data show that for x > 20 mol%, the Cu²⁺ ions are predominantly clustered and are coupled through antiferromagnetic exchange interaction. A comparative study of amorphous X-ray diffraction pattern of the glasses indicates a structural modification in the TeO₂ network with increasing CuO concentration; the effect is quite visible in the samples with CuO concentrations higher than 20 mole percent. Measurements of density corroborate the conclusions drawn from the X-ray diffraction. Additionally, we show that our data validates a model in which CuO rich regions are surrounded by a buffer boundary which separates them from the tellurite glassy network; effect of introducing B₂O₃ can be best described as breaking these regions into smaller size regions. Received 23 October 2000 and Received in final form 1st February 2001