Mixed micellar aggregates of nonionic surfactants with short hydrophobic tails

Mixed micelle formation by aqueous mixtures of pentaethylene glycol monohexyl ether (C₆E₅) and diethylene glycol monohexyl ether (C₆E₂) has been investigated by determining the temperature-composition phase diagrams and measuring the intradiffusion coefficients. In binary aqueous solutions, C₆E₅ shows a high tendency to micellize, while C₆E₂, because of its too short hydrophilic head, presents a macroscopic phase separation in a water-rich and a surfactant-rich phases. The temperature-composition phase diagrams obtained for the ternary water-C₆E₅---C₆E₂ mixtures present a micellar region in which both surfactants co-aggregate. The dimensions of this micellar region depend on the relative ratio between the two surfactants molalities. By analysing the micelle intradiffusion coefficient, measured through the PGSE-NMR technique, the hydrodynamic radius of the aggregates has been estimated at 25 °C. It is similar to that of triethylene glycol monohexyl ether (C₆E₃) in binary aqueous solution. The experimental evidences suggest that in mixed ethoxylated surfactants the micellar behaviour is mainly determined by the mean number of ethoxylic units per surfactant molecule, independently of their distribution.     

Calculation of Half-Metal,Debye and Curie Temperatures of Co_2 VAl Compound: First Principles Study

By FP-LAPW calculations, the structural, elastic, Debye and Curie temperatures, electronic and magnetic properties of Co2 VAl are investigated. The results indicate that Ferromagnetic(FM) phase is more stable than AntiFerromagnetic(AFM) and Non-magnetic(NM) ones. In addition, C11–C12 0, C44 0, and B 0 so Co2 VAl is an elastically stable material with high Debye temperature. Also, the B/G ratio exhibits a ductility behavior. The relatively high Curie temperature provides it as a favorable material for spintronic application. It's electronic and magnetic properties are studied by GGA+U approach leading to a 100% spin polarization at Fermi level.     

光谱参数法快速识别石油烃污染场地水体特征

水体受石油污染日趋广泛,给人类及生态环境带来严重威胁.快速、准确和可靠地监测水体石油污染状况,对于理解其环境行为和评估人体暴露风险至关重要.石油类组分往往具备较好的光谱响应,然而基于光谱技术快速监测实际石油烃污染水体却鲜有报道.该研究以典型石油污染场地的地下水和地表水为对象,在全面分析水质电导率、总有机碳,Cl-,NO...     

梯度掺杂体异质结对有机太阳能电池光电转换效率的影响

基于传统的体异质结有机太阳能电池结构, 对结构中的混合层改用梯度掺杂的方法, 在AM1.5, 100 mW/cm²光照下, 使得器件的短路电流由原来的7.72 mA/cm²提高到了9.18 mA/cm², 相应的光电转换效率提高了25%. 器件性能的提升归因于梯度掺杂体系的引入使得体异质结混合层中同一材料分子之间形成了较好的连续网络结构, 降低了器件的串联电阻, 提高了电极对载流子的收集效率, 从而提高了器件的光电转换效率. 关键词： 有机太阳能电池 体异质结 梯度掺杂     

(C_5H_(11)N_2)~+和(C_7H_(12)N_2)~(2+)的NMR研究

结合1H NMR,13C NMR谱,分别对钨、钼配合物{WO2(C10H6O2)2(C5H11N2)2[H2N(CH2)3NH2]}3(1),{(C5H11N2)2[H2N(CH2)3NH2][MoO2(C10H6O2)2]}(2),{(C7H12N2)2[MoO2(C10H8O2)2]}(3)晶体结构中小分子环进行了归属.其中,配合物1和2中(C5H11N2)+的NMR研究证实了六元环由1,3-丙二胺和乙腈化合而成,配合物3中(C7H12N2)2+的NMR谱图证实了七元环由乙二胺和乙酰丙酮化合而成,并且推导出这些亲核加成-消除反应的反应机理.配合物1~3中的小分子环的合成在其它体系中尚未见报导,而在合成它们的反应中作为新产物随主体晶体析出,并由晶体结构解析和NMR得到了证实.     

N2在页岩干酪根上的吸附特征

采用密度泛函理论的wB97XD方法、RDG函数方法和counterpoise correction理论,研究氮气在干酪根C₂₈H₁₄O和氮掺杂干酪根C₂₇H₁₄ON上的吸附特征。结果表明：N₂在干酪根上的活性吸附位点为苯环上方中心位置,吸附能在8~10 kJ·mol^-1之间,N₂和干酪根之间的相互作用主要是范德华相互作用和空间排斥作用。氮掺杂改变了干酪根的构型和电子云分布,导致含氮杂环不再是稳定的活性吸附位点,增强了排斥作用,使吸附能略有减小。研究结果对理解干酪根吸附小分子的特征有重要意义,能够为页岩气的开采提供理论支持。     

First-principles Study on the Magnetic,Half-metal and Thermoelectric Transport Properties of Inorganic-Organic Hybrid Compounds [C4N2H12][Fe4Ⅲ(HPO3)2(C2O4)3]

The electronic structure, magnetic and half-metal properties of inorganic-organic hybrid compound [C₄N₂H₁₂][Fe₄^Ⅲ(HPO₃)₂(C₂O₄)₃] are investigated by using the full-potential linearized augmented plane wave (FPLAPW) method within density-functional theory (DFT) calculations. The density of states (DOS), the total energy of the cell and the spontaneous magnetic moment of [C₄N₂H₁₂][Fe₄^Ⅱ(HPO₃)₂(C₂O₄)₃] are calculated. The calculation results reveal that the low-temperature phase of [C₄N₂H₁₂][Fe₄^Ⅲ(HPO₃)₂(C₂O₄)₃] exhibits a stable ferromagnetic (FM) ground state, and we find that this organic compound is a half-metal in FM state. In addition, we have calculated antiferromagnetically coupled interactions, revealing the existence of antiferromagnetic (AFM), which is in agreement with the experiment. We have also found that [C₄N₂H₁₂][Fe₄^Ⅲ(HPO₃)₂(C₂O₄)₃] is a semiconductor in the AFM state with a band gap of about 0.40 eV. Subsequently, the transport properties for potential thermoelectric applications have been studied in detail based on the Boltzmann transport theory.     

含R2NCS2配体的Mo(W)-Cu-S簇合物的1H NMR研究

报道了十一个含R₂NCS₂配体的Mo (W)-Cu-S簇合物的,¹H NMR研究结果,表明异金属簇合物导致配体中α-H的NMR谱线严重加宽.对谱线的位移,化合物的结构及配位键键长L_Cu-s之间的关系也作了讨论.     

Co_(2~-)基Heusler合金Co_2FeAl_(1–x)Si_x(x=0.25,x=0.5,x=0.75)的结构、电子结构及热电特性的第一性原理研究

运用基于密度泛函理论的第一性原理方法,对Co_2FeAl_(1–x)Si_x(x=0.25, 0.5, 0.75)系列Heusler合金的电子结构、四方畸变、弹性常数,声子谱以及热电特性进行了计算研究.结果显示, Co_2FeAl_(1–x)Si_x系列合金的电子结构均为半金属特性,向下自旋态(半导体性)均呈现良好的热电特性,并且随着硅原子浓度的增加功率因子随之增加.计算的声子谱不存在虚频,均满足动力学稳定性条件,弹性常数均满足玻恩稳定性条件,机械稳定性均良好.随着晶格常数c/a的比值变化,体系的能量最低点均出现在c/a=1处,即结构稳定性不随畸变度c/a的变化而变化,说明不存在马氏体相变.此系列合金薄膜的电子结构呈现较高的自旋极化率,在替代浓度x=0.75时自旋极化率达到100%,且当x=0.75时薄膜在畸变度c/a=1.2时存在马氏体相变.随着晶格畸变度的改变,总磁矩也发生变化,且主要由Fe和Co两种过渡金属原子的磁矩变化所决定.     

便携式FTIR的机动车尾气检测方法

随着汽车排放标准的提高,相关VOC标准从总烃检测变为非甲烷碳氢化合物(NMHC)检测;随着含氧燃料的增加,增加了非甲烷有机气体(NMOG)测量。针对国内汽车尾气分析仪分析组分单一、精度有限、VOCs检测过程复杂等问题,提出了基于便携式FTIR的机动车尾气检测方法,基于立体角镜优化FTIR光学系统结构,提高动镜扫描速度,设计便携式且满足抗振动需求的快速FTIR光谱仪。FTIR红外光源输出波段范围为2～20 μm,分辨率为0.5 cm-1,扫描速度1 Hz,气体池光程为10 m,采用斯特林探测器,其光谱响应范围为600～6 000 cm-1。选择CH₄,C₂H₂,C₂H₄,C₂H₆,C₃H₆,n-C₅H₁₂,i-C₅H₁₂,C₇H₈,HCHO,C₂H₅OH,CH₃CHO这些典型HC化合物作为VOC气体检测的替代物。通过标准谱确定尾气成分的波段为900～1 100和2 700～3 100 cm-1,涵盖所有待测气体吸收波段。基于AVL台架测试,开展NEDC和WLTC工况实验测试,测试车辆为丰田威驰,测试油品为92号国五。便携式FTIR采用抽取方式进行尾气测量,原始的废气样本来自安装在排气管延长部分的多孔探头,前端安装样气取样装置,主要包括颗粒物过滤和除水汽装置,以防止污染FTIR光学系统。实验表明FTIR可以有效快速测量汽车尾气中CO,CH₄,NO和主要HC化合物,在FTIR检测限0.5 μmol·mol-1下会引入噪声信号,浓度可信度降低。通过分析可以看出输出气体平均浓度降级排列依次是：CO,C₂H₄,CH₄,NO,i-C₅H₁₂,C₂H₆,C₇H₈,n-C₅H₁₂,C₂H₅OH,CH₃CHO。从3个循环的NEDC工况可以看出,每种气体排放呈现一致的规律性变化。针对CO进行了SEMTECH-DS与FTIR测量数据的时间序列比较,结果呈现了较好的规律一致性,但是由于FTIR和SEMTECH-DS测量技术和取样稀释系统不同导致二者浓度差异较大。与传统尾气检测技术相比,便携式FTIR测量系统对瞬态事件有良好的响应,可以在线进行多组分浓度实时测量获取机动车的瞬时排放数据,在满足新规测试要求下,也可以为后期的机动车在实际道路上的排放特征分析和模拟提供可靠的数据支持。     

基于Raman与FTIR对掺甲烷乙烯/氢气扩散火焰碳烟有序度和官能团的研究

以甲烷、乙烯、氢气混合扩散火焰碳烟为研究对象,采用激光共聚焦拉曼光谱（Raman）和傅里叶红外光谱（FTIR）研究了不同掺甲烷比例下乙烯、氢气混合火焰碳烟有序度及官能团的分布特性,分析了碳烟石墨化和官能团分布,揭示了掺甲烷对乙烯/氢气（氢气比例30%）层流扩散火焰的碳烟生成影响规律。Raman研究表明在甲烷掺混比为3%和7%时,在火焰高度低于4cm位置生成的碳烟有序程度显著降低,表明在此区域存在明显的碳烟生成协同效应;甲烷掺混比增大超过10%时,协同效应基本消失,碳烟有序度上升。FTIR研究表明掺混甲烷对碳烟官能团组成影响明显。掺混甲烷后脂肪族官能团相对含量整体提高。随着甲烷掺杂比的增大,CH₂相对含量增大到一峰值后减小。碳烟中芳香族官能团含量随着火焰高度的上升含量下降明显。掺混3%和7%甲烷,芳香族官能团在2和3 cm火焰高度时,芳香族官能团的含量明显上升。掺混甲烷比高于10%时,芳香族官能团的含量则有所降低。表明少量甲烷掺混使得CH₃和C₃H₃生成有了新的途径,CH₃和C₃H₃增加,而C₂H₄和C₂H₂减少不明显,从而促进了多环芳香烃(PAHs)的生成。继续增加甲烷因为稀释作用会抑制C₂H₂生成从而减少PAHs的生成,芳香族相对含量降低,因而降低了碳烟的生成。研究揭示了甲烷对乙烯/氢气层流扩散火焰中碳烟形成的相互作用：在低甲烷掺混比时存在协同效应促进碳烟生成,而在高甲烷掺混比时协同效应消失。     

Substrate-induced freezing of alkane monolayers adsorbed on Au(1 1 1) dependant on the alkane/gold misfit

The molecular structure of the interfaces between pure C_nH_2n+2 (n=10, 12, 14, 16) and Au(1 1 1) surface has been studied by scanning tunneling microscopy. At 291 K, self-organized monolayers with a lamella structure are formed with these alkanes. The ordered monolayers are melting at temperature higher by 46, 28, 15, 5 K than the melting point of bulk C_nH_2n+2 crystals with n=10, 12, 14, 16, respectively. Two kinds of melting process were observed: (i) a direct solid/liquid phase transition within the monolayer for C₁₀H₂₂, C₁₂H₂₆ and C₁₄H₃₀ molecules, (ii) an intermediate phase for C₁₆H₃₄ molecules. This mesophase corresponds to a two-dimensional liquid crystal formed by molecules moving along their axis and along Au1 1 0. These results agree well with calculations using a geometric model taking in account the misfit between the CH₂–CH₂–CH₂ period along alkyl chain and the gold lattice along 1 1 0 direction.     

荧光光谱定量表征不同成熟度的同源混合原油——以东营凹陷沙四段为例

混源油比例定量分析对于判识不同成藏期的油源贡献度具有重要意义,为建立一种快捷确定混源油贡献度的方法,采用显微荧光光谱技术对同源混合原油贡献度进行了定量表征。以东营凹陷王家岗地区为例,通过γ蜡烷/C₃₀霍烷、Ts/(Tm+Ts)、Ts/Tm及C₂₉20S/（20S+20R）等生物标志化合物参数对沙四段原油进行了的原油组群划分与油源对比,对原油类型和成熟度进行了限定。选择具有代表性的X₁和X₂井作为沙四型成熟原油和低熟原油的两个端元组分进行人工配比实验,在验证端元组分可靠性的基础上,对端元油按照质量分数进行了配比,分别为0∶10,2∶8,4∶6,6∶4,8∶2,10∶0。对配比进行了原油族组分和显微荧光光谱分析,分析了混合原油成熟度、端元油贡献度和荧光光谱参数之间的关系。结果表明：配比混源油继承了端元油“三峰型”的荧光光谱谱形特征,混源油荧光颜色明显不同,通过荧光颜色定量系数（CIE-X,CIE-Y）分析可知,在CIE色度图上表现为近线性渐变的荧光特征;随着沙四型成熟油混入量的增加,混源油中芳香烃含量逐渐减少,荧光强度也逐渐降低,荧光颜色发生了明显的蓝移;原油混合使荧光光谱参数发生了变化,荧光光谱参数（QF-535、荧光强度-567 nm、红绿商、黄绿商）与混合比例呈现良好的线性关系,能够较好的反映原油成熟度;随着混源油成熟度增高,高分子量烃类组分含量降低,荧光光谱参数逐渐降低。通过配比实验建立的数学关系能够定量判别原油混合比例,实验证实可以利用荧光光谱参数定量表征混源油中端元组分的贡献度。     

Small angle neutron scattering study of temperature-independent formulation of mixed micellar structures

SANS measurements have been performed on mixed systems of ionic surfactant sodium dodecyl sulphate (SDS) and nonionic surfactant polyoxyethylene 10 lauryl ether (C12E10). The total concentration of the mixed system was kept fixed (10 wt%) and the ionic to nonionic surfactant ratio varied in the range 0 to 1. The temperature effect on the structures of mixed micelles has been studied for temperatures between 30 and 75°C. Micelles of pure ionic and nonionic surfactants show opposite trends when the temperature is increased. Sizes of pure ionic micelles decrease and those of nonionic micelles increase with increase in temperature. We show a formulation balancing these two effects which is temperature-independent and consists of about 25% of ionic surfactants in the mixed system. Contrast variation SANS measurements by contrast matching one of the surfactant components to the solvent suggest homogeneous single mixed micelles of the two components in the mixed systems.      

X@C20F20(X=He,Ne,Ar,Kr)几何结构和 电子结构的理论研究

采用密度泛函理论中的广义梯度近似, 对X@C₂₀F₂₀(X=He, Ne, Ar, Kr)几何结构和电子结构进行了计算研究. 几何结构优化发现: 惰性气体原子X内掺到C₂₀F₂₀笼后, 均稳定于碳笼中心, 随着内掺X原子序数的增大, X原子对C₂₀F₂₀笼的影响越来越大. 能隙、内掺能和振动频率计算表明: 内掺X原子使得C₂₀F₂₀的稳定性得到了显著提升, X@C₂₀F₂₀(X=He, Ne, Ar, Kr)都具有良好的稳定性, 并且随着X原子序数的增大, 其稳定性也基本呈现逐渐增强的趋势. 电子结构研究发现: X原子对X@C₂₀F₂₀费米能级附近的占据轨道基本没有贡献, 而对其未占据轨道贡献较大. 计算还发现: 在X@C₂₀F₂₀中, He 和Kr分别从C₂₀F₂₀的C 笼上获得了0.126和0.271个电子, 而Ne和Ar却分别向C笼转移了0.060和0.012个电子. 由此可见: X原子与C原子之间都发生了电荷转移, C笼上的C原子与惰性气体原子X间形成了一定的离子键.     

Interaction of CO2 with Cs-promoted Fe(110) as compared to Fe(110)/K+CO2

The interaction of CO₂ with Cs-promoted Fe(110) at 85 K as well as temperature-dependent reactions between 100 and 700 K have been studied by means of ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). Several surface species could be detected at 85 K, i.e. carbon monoxide (CO), carbonate (COⁿ⁻₃), physisorbed linear carbon dioxide (CO^lin₂) and very small amounts of oxidic oxygen (O_ox). An oxalate species (C₂O^m−₄) could not be identified definitively, but from comparison with the literature there is evidence that C₂O^m−₄ is present. Increasing the temperature after saturation with CO₂ leads to a complicated reaction behaviour. CO₂ either desorbs or dissociates into CO and COⁿ⁻₃ or forms C₂O^m−₄ at temperatures between 85 and 160 K. Above 160 K C₂O^m−₄, decomposes in parallel reactions into CO₂, COⁿ⁻₃ and CO. Above 320 K, adsorbed CO either desorbs into the gas phase or dissociates into C and O. In the temperature region between 500 and 700 K a recombination of C and O to CO and the desorption of Cs take place. As in the case of Fe(110)/K+CO₂, at high alkali coverages two carbonate species could be detected which dissociate upon heating at different temperatures. The system Fe(110)/Cs+CO₂ is proved to be very similar to the system Fe(110)/K+CO₂.     

西藏扎什伦布寺壁画的科学研究

壁画是寺院建筑的重要装饰元素,也是藏传佛教艺术的重要组成部分。扎什伦布寺始建于明正统12年（公元1447年）,作为后藏最大的寺院,寺内保存了大量精美壁画,这些壁画对研究藏传佛教及佛教艺术具有重要意义。扎什伦布寺自建寺起一直为传播佛教文化服务,经历了频繁的大规模修建。为了解扎什伦布寺壁画的制作材料与工艺,为今后壁画的保护及修复提供重要的参考及科学支撑,选取寺内强巴佛殿四层北壁、吉康扎仓南殿西侧的典型壁画,共采集8个样品。采用超景深三维视频显微镜观察壁画的制作结构,显微激光拉曼光谱仪对有机与无机颜料的成分信息进行表征,偏光显微镜根据晶体的光学信息鉴别拉曼光谱相似的颜料颗粒,X射线衍射仪用于测定地仗成分,扫描电镜/能谱仪则对微观数据进行确认和补充。通过分析研究,壁画由地仗层、准备层、颜料层构成。颜料包括矿物及人工合成颜料,其中红色颜料为朱砂与颜料红14,绿色颜料为块铜矾、酞菁绿,黑色颜料为碳黑,黄色颜料为雌黄,蓝色颜料为合成群青。颜料红14与酞菁绿为有机合成颜料,合成群青则为无机合成颜料。块铜矾作为矿物颜料,在欧洲曾用于架上画、壁画、手稿等艺术作品中,但在国内还未曾发现其使用历史,这一发现扩展了对绿色颜料的认识。壁画的地仗层依据藏式壁画制作传统使用了阿嘎土,准备层则由黄土制备。研究结果表明,壁画制作时以阿嘎土打底,刷一层黄土找平壁面,以胶调和颜料绘制于黄土层之上。壁画除了使用一些常见的传统藏式壁画材料,还发现了一些近代人工合成材料,说明扎什伦布寺强巴佛殿四层北壁及吉康扎仓南殿西侧壁画曾经历过重绘或补绘。该研究结果不仅弥补了扎什伦布寺壁画的研究空缺,也为扎什伦布寺修缮历史的补充及完善提供了重要证据。     

用八孔耦合器识别TM0_(1)/TE_(11)混模中TE_(11)模式的方法北大核心CSCD

在高功率微波传输系统中,为了提高功率容量和效率,往往采用过模波导,因此圆波导中往往出现TM_(01)和TE_(11)混合模式的情况。采用角向均匀分布的8孔圆波导耦合器,对提取TE_(11)模式的混合比和极化角度的方法进行了分析和研究。分析了圆波导中TM_(01)和TE_(11)模式在耦合孔处的电场分布,并采用CST对各耦合孔的输出功率进行了模拟计算,得出相互正对的耦合孔的平均功率与8个孔的平均功率之比与模式之间的相位差无关的结论。同时,发现该比值与TE_(11)模式的混合比成线性关系,线性关系中的比例系数是极化角度线性函数。通过线性拟合获得了计算TE_(11)模式混合比和极化方向的表达式。与仿真设定的参数相比,用该表达式计算的结果表明,在TE_(11)模式混合比小于30%时,用其计算TE_(11)模式的混合比和极化角度是可行的,误差不超过10%。在此基础上,给出了实际情况下TE_(11)模式信息的具体判断方法。     

Studies of fullerenes by the excitation, emission, and scattering of electrons

This paper presents an overview of how electron spectroscopies have contributed to advances in fullerene research. In particular, we illustrate the vital role these techniques have played in improving our understanding of the importance of strong electronic correlation and of electron-phonon coupling in these materials, in the derivation of electron hopping rates, in providing a direct determination of charge transfer and hybridisation in both fullerene salts and adsorbed fullerenes and in determining the optical gap of these systems. We discuss systems of increasing complexity, starting with C₆₀ in the gas phase and in the solid state, and moving on to C₆₀ salts and to C₆₀ adsorbed on surfaces. Finally we look at both higher fullerenes and fullerenes with a heteroatom either on or inside the cage.     

Optical anisotropy and the direction of polarization of exciton emissions in a semiconductor quantum dot:Effect of heavy-and light-hole mixing

The dependence of the directions of polarization of exciton emissions, fine structure splittings(FSS), and polarization anisotropy on the light-and heavy-hole(LH–HH) mixing in semiconductor quantum dots(QDs) is investigated using a mesoscopic model. In general, all QDs have a four-fold exciton ground state. Two exciton states have directions of polarization in the growth-plane, while the other two are along the growth direction of the QD. The LH–HH mixing does affect the FSS and polarization anisotropy of bright exciton states in the growth-plane in the low symmetry QDs(e.g., C_(2V),C_S, C_1), while it has no effect on the FSS and polarization anisotropy in high symmetry QDs(e.g., C_(3V), D_(2d)). When the hole ground state is pure HH or LH, the bright exciton states in the growth-plane are normal to each other. The LH–HH mixing affects the relative intensities and directions of bright exciton states in the growth-plane of the QD. The polarization anisotropy of exciton emissions in the growth-plane of the QD is independent of the phase angle of LH–HH mixing but strongly depends on the magnitude of LH–HH mixing in low symmetry QDs.