Wave turbulence and intermittency in directional wave fields

The evolution of surface gravity waves is driven by nonlinear interactions that trigger an energy cascade similarly to the one observed in hydrodynamic turbulence. This process, known as wave turbulence, has been found to display anomalous scaling with deviation from classical turbulent predictions due to the emergence of coherent and intermittent structures on the water surface. In the ocean, waves are spread over a wide range of directions, with a consequent attenuation of the nonlinear properties. A laboratory experiment in a large wave facility is presented to discuss the sensitivity of wave turbulence on the directional properties of model wave spectra. Results show that the occurrence of coherent and intermittent structures become less likely with the broadening of the wave directional spreading. There is no evidence, however, that intermittency completely vanishes.     

Functionalized Silver-Ion-Mediated α-dC/β-dC Hybrid Base Pairs with Exceptional Stability: α-d-5-Iodo-2′-Deoxycytidine and Its Octadiynyl Derivative in Metal DNA

Silver-mediated α-dC–Ag⁺–β-dC hybrid base pairs decorated with 5-iodo- or 5-octadiynyl residues are well accommodated in duplex DNA. A strong T_m increase and favorable thermodynamic data for duplex DNA were observed after addition of silver ions. The phenomenon is particularly obvious when both nucleobases of the base pairs are functionalized. Neither the position of the base pair, nor the type of 5-substituent had a negative influence. On the contrary, functionalization of conventional silver-mediated β-dC–Ag⁺–β-dC homo base pairs showed a negative impact induced by the bulky substituents. To this end, cytosine modified 12-mer oligodeoxynucleotides were prepared by solid-phase synthesis employing new α-anomeric 2′-deoxycytidine phosphoramidites. A multigram scale synthesis was developed for 5-iodo-α-d -2′-deoxycytidine ( 1 ) employing the direct glycosylation of cytosine with Hoffer's α-d -halogenose followed by separation of anomeric DMT nucleosides. Regarding base-pair stability and functionalization silver-mediated α/β-dC hybrid base pairs were found to be superior to β/β-dC homo pairs. According to their extraordinary properties, they might find applications in DNA diagnostics, material science, or nanotechnology.     

基于吸收系数的生脉注射液中聚山梨酯80含量测定新方法

聚山梨酯80又名吐温80，为一种亲水型非离子表面活性剂，是食品、保健品和药品中常用的辅料，作为增溶剂和澄清剂广泛用于中药注射剂。近年来，不良反应的发生使得聚山梨酯80的质量和应用愈加受到重视，有研究认为其加入可能引起注射剂不良反应增加。为避免超量使用，有必要对该辅料的投料加以严格控制。中药注射剂中聚山梨酯80的含量测定是当下研究的热点和难点，可以通过分光光度法、分子排阻-蒸发光散射检测法(SEC-ELSD)、液质联用法(LC-MS)直接测定，也可以水解后法经液相色谱-紫外检测法(HPLC-UV)或气相色谱法(GC)间接测定。但由于聚山梨酯80为聚氧乙烯聚合数目不同的混合物、不同厂家生产的聚山梨酯80化学组分及比例存在较大差异，难以采用统一的转换公式或对照品准确定量。此外，中药注射剂的复杂基质造成的假阳性干扰也对定量提出了挑战。为解决以上问题，以生脉注射液为例，提出基于吸收系数的中药注射剂中聚山梨酯80含量测定新方法。优化检测波长、显色剂种类、液液萃取过程振荡和静置时间，在6个不同品牌仪器上测得聚山梨酯80-硫氰酸钴配合物的吸收系数(E1%_{1 cm})为104.23，相对标准偏差(RSD)为2.08%。生脉注射液稀释10倍后，精密量取供试品溶液1.0 mL，精密加入硫氰酸钴溶液10 mL，二氯甲烷20 mL，涡旋振荡3 min。将混合液移至分液漏斗中，静置30 min，取下层二氯甲烷液，将前1 mL弃去，接收约15 mL，在320 nm处测定吸光度，再根据Lambert-Beer定律，利用获得的吸收系数计算得到聚山梨酯80的含量。方法阴性无干扰，精密度和重复性相对标准偏差均低于3%，平均回收率为98.42%。为进一步验证方法的准确性，分别采用吸收系数法和标准曲线法测定了2个厂家的10批生脉注射液，并与实际投料量比较。配对t检验结果表明，当置信度为95%时，两种方法无显著性差异，吸收系数法测得结果与企业生产中聚山梨酯的实际投料量也无显著性差异。研究采用前人未采用的、灵敏度更高的320 nm为检测波长，显著降低了基质干扰，克服了中药注射剂中聚山梨酯80测定结果与实际投料量难以吻合的问题。吸收系数法无需使用对照品，亦不用制备标准曲线，可为中药注射剂中聚山梨酯80的检查标准提供切实可行的解决方案。所建方法灵敏、准确、快速、简便，为含聚山梨酯80制剂的质量控制提供了关键常数及新的思路。     

焦炉上升管内壁结焦炭层的光谱学分析及结焦机理研究

以焦炉上升管内壁结焦炭层块为研究对象，采用X射线荧光光谱仪（XRF）、X射线衍射仪（XRD）、傅里叶红外光谱仪（FTIR）和激光共聚焦拉曼光谱仪（Raman）对结焦炭层的元素组成，以及各结焦炭层的矿物组成、组成结构和分子结构进行测试。分析从结焦炭层块外表面向内表面过渡的各结焦炭层的差异性，揭示焦炉上升管内壁结焦机理。结果表明焦炉上升管内粉尘中Fe，S和Cr极易催化荒煤气中蒽、萘等稠环芳烃化合物成炭，在焦炉上升管内壁形成炭颗粒沉积，为焦油凝结挂壁提供载体，在荒煤气温度降至结焦温度时易结焦积碳。结焦炭层均含有芳香层结构，随着结焦炭层从外表面向内表面过渡，各结焦炭层的面层间距(d₀₀₂)逐渐降低、层片直径(L_a)先降低后增加、层片堆砌高度(Lc)和芳香层数(N)先稳定后增加。结焦炭层石墨化过程是由结焦炭层内表面向外表面进行，主要包括其片层外缘的羧基和部分C-O结构的降解剥离，从而形成高度规整的共轭结构。结焦炭层块中C元素是以结晶碳与无定型碳的混合物形式存在。以上研究为解决焦炉上升管内壁结焦及腐蚀问题，提高换热器换热效率，有效回收焦炉荒煤气显热，降低焦化企业能耗提供实验基础和理论依据。     

激光产生的铝、硅、氧、铜、硒等离子体X光谱

利用长晶格的OHM晶体谱仪,从激光等离子体中获得丰富的铜、硒类氖、类氟、类钠离子的二、三、四级软X射线衍射光谱和铝、氧、硅的类氢、类氦、类锂离子一到四级谱,波长在14～40(?)之间,在此基础上,本文较为细仔地分析了各光谱结构.     

[Na(18-C-6)]2[Cu(i-mnt)2]的合成与结构分析

研究了18-冠-6与Na2[Cu(i-mnt)2][i-mnt=异丁二腈烯二硫醇阴离子,S2CC(CN)2-2]的反应,得到的配合物[Na(18-C-6)]2[Cu(i-mnt)2](1)通过元素分析、红外光谱、X射线单晶衍射进行了结构分析.配合物为单斜晶系,空间群P2(1)/c.晶体学结构数据a=1.2819(11),b=1.1793(10),c=1.4928(13)nm,β=99.121(16)°,V=2.228(3)nm3,Z=2,Dcaled.=1.369g/cm3,F(000)=958,R1=0.0521,wR2=0.1003.1中的[Cu(i-mnt)2]基团通过配体i-mnt的氮原子与两个[Na(18-C-6)]基团中的钠原子成键,形成稳定的中性配合物.     

Preparation, structure and properties of novel 1,3-dithiol-2-ylidene derivatives containing bis(ethynylpyridine) units

1,3-Dithiol-2-ylidene derivatives containing bis(ethynylpyridine) units were synthesized using a Pd-catalyzed reaction of the corresponding dibromide. X-Ray crystal analysis revealed unique crystal structures depending on the aromatic groups. The absorption spectra and redox properties indicated intramolecular charge-transfer interactions between the 1,3-dithiole unit and the pyridyl parts.     

X-Ray Mapping and Interpretation of Scatter Diagrams

Electron beam induced quantitative X-ray mapping has become a very useful characterisation tool for determining the elemental distribution in materials, whether using energy dispersive spectroscopy or wavelength dispersive spectroscopy. The X-ray intensity distributions of the elements from an X-ray map allow us to generate two dimensional and ternary scatter diagrams thus converting spatial information into concentration dimensions, which is an important tool for displaying the spatial relationships of elements or correlated elements (phases) in materials. To best understand how to use this tool, we need to understand the production and features of the scatter diagram. The type of clustering observed in the scatter diagram, whether oval, linear or spherical, can give the major and trace element distributions within phases as well as qualitative and quantitative phase information. This paper demonstrates the generation of scatter diagrams, properties of scatter diagrams, interpretation of scatter diagrams and the advantages of scatter diagrams through the use of examples.     

An AFM, XPS and electrochemical study of molecular electroactive monolayers formed by wet chemistry functionalization of H-terminated Si(1 0 0) with vinylferrocene

Molecular electroactive monolayers have been produced from vinylferrocene (VFC) via light-assisted surface anchoring to H-terminated n- and p-Si(1 0 0) wafers prepared via wet chemistry, in a controlled atmosphere. The resulting Si-C bound hybrids have been characterized by means of XPS and AFM. Their performance as semiconductor functionalized electrodes and their surface composition have been followed by combining electrochemical and XPS measurements on the same samples, before and after use in an electrochemical cell. White-light photoactivated anchoring at short (1 h) exposure times has resulted in a mild route, with a very limited impact on the initial quality of the silicon substrate. In fact, the functionalized Si surface results negligibly oxidized, and the C/Fe atomic ratio is close to the value expected for the pure molecular species. The VFC/Si hybrids can be described as (η⁵-C₅H₅)Fe²⁺(η⁵-C₅H₄)-CH₂-CH₂-Si species, on the basis of XPS results. Electrochemical methods have been applied in order to investigate the role played by a robust, covalent Si-C anchoring mode towards substrate-molecule electronic communication, a crucial issue for a perspective development of molecular electronics devices. The response found from cyclic voltammograms for p-Si(1 0 0) functionalized electrodes, run in the dark and under illumination, has shown that the electron transfer is not limited by the number of charge carriers, confirming the occurrence of electron transfer via the Si valence band. The hybrids have shown a noticeable electrochemical stability and reversibility under cyclic voltammetry (cv), and the trend in peak current intensity vs. the scan rate was linear. The molecule-Si bond is preserved even after thousands of voltammetric cycles, although the surface coverage, evaluated from cv and XPS, decreases in the same sequence. An increasingly larger surface concentration of Fe³⁺ at the expenses of Fe²⁺ redox centers has been found at increasing number of cv’s, experimentally associated with the growth of silicon oxide. Surface SiO⁻ groups from deprotonated silanol termination, induced by the electrochemical treatments, are proposed as the associated counterions for the Fe³⁺ species. They could be responsible for the observed decrease in the electron transfer rate constant with electrode ageing.