Oligonucleotide Functionalized Microporous Gold Electrode for the Selective and Sensitive Determination of Mercury by Differential Pulse Adsorptive Stripping Voltammetry (DPAdSV)

Abstract

A novel electrode modified with oligonucleotide and microporous gold was fabricated for the determination of mercury by differential pulse adsorptive stripping voltammetry (DPAdSV). Microporous gold was synthesized by electrochemical reduction using dynamic hydrogen bubble template. The oligonucleotide was immobilized on microporous gold by self-assembly. The prepared electrode exhibited an improved electrochemical response for mercury(II) ion because of the large surface area and excellent electron transfer capacity provided by microporous gold and the specific coordination between mercury ion and thymine bases in oligonucleotides. Under the optimal experiment conditions, the oligonucleotide functionalized microporous gold electrode had a linear relationship between the stripping current and mercury ion concentration in the range from 0.5 to 30?µg/L with a detection limit of 0.021?µg/L. Moreover, the prepared electrode exhibited good selectivity, reproducibility, repeatability and stability. Furthermore, the prepared electrode was applied to detect mercury in tap water with satisfactory results.     

Radiation analytical material characterization of diamond layers deposited onto tungsten carbide

The characterization of diamonds deposited onto WC single crystals by means of the CVD-method is reported. Investigations were performed by scanning electron microscopy, X-ray diffraction methods and the Kossel reflection technique. Single diamond crystals were deposited in the form of icosahedrons. An orientation correlation between substrate single crystal and diamond crystals could not be proved. In the paper presented, reasons will be given for this fact.     

Synthesis and characterization of polyamides and poly(amide-imide)s derived from 2,2-bis(4-aminophenoxy) benzonitrile

A series of polyamides and poly(amide-imide)s were prepared by the direct poly-condensation of 2,2-bis(4-aminophenoxy) benzonitrile [4-APBN] with aromatic dicarboxylic acids and bis(carboxyphthalimide)s in N-methyl-2-pyrrolidone [NMP] with triphenyl phosphite and pyridine as condensing agents. The synthesis of 4-APBN involves a nucleophilic displacement reaction in dipolar aprotic solvent with the alkali metal salt of p-aminophenol and an activated aromatic dichloro compound. Bis(carboxyphthalimide)s were prepared by condensation of 4,4^′-diaminodiphenylsulfone, 3,3^′-diaminodiphenylsulfone, 4,4^′-diaminodiphenylether, 4,4^′-diaminodiphenylmethane, 3,3^′-diaminobenzophenone, and trimellitic anhydride at a 1:2 molar ratio. The inherent viscosities of the resulting polymers were found to be in the range of 0.31-0.93 dl/g and glass transition temperatures between 235 and 298 °C. All polymers were soluble in aprotic polar solvents such as dimethylsulfoxide and NMP. The results of thermogravimetry revealed that all the polymers showed no significant weight loss before 400 °C. Wide-angle X-ray diffractograms revealed that all polymers were found to be amorphous except for the polyamide derived from isophthalic acid and polyamide-imides derived from diaminodiphenylether and diaminobenzophenone based bis(carboxyphthalimide)s.     

Synthesis and characterization of organosoluble,thermoplastic elastomer/clay nanocomposites

We synthesized organosoluble, thermoplastic elastomer/clay nanocomposites by making a jelly like solution of ethylene vinyl acetate containing 28% vinyl acetate (EVA‐28) and blending it with organomodified montmorillonite. Sodium montmorillonite (Na⁺‐MMT) was made organophilic by the intercalation of dodecyl ammonium ions. X‐ray diffraction patterns of Na⁺‐MMT and its corresponding organomodified dodecyl ammonium ion intercalated montmorillonite (12Me‐MMT) showed an increase in the interlayer spacing from 11.94 to 15.78 Å. However, X‐ray diffraction patterns of the thermoplastic elastomer and its hybrids with organomodified clay contents up to 6 wt % exhibited the disappearance of basal reflection peaks within an angle range of 3–10°, supporting the formation of a delaminated configuration. A hybrid containing 8 wt % 12Me‐MMT revealed a small hump within an angle range of 5–6° because of the aggregation of silicate layers in the EVA‐28 matrix. A transmission electron microscopy image of the same hybrid showed 3–5‐nm 12Me‐MMT particles dispersed in the thermoplastic elastomer matrix; that is, it led to the formation of nanocomposites or molecular‐level composites with a delaminated configuration. The formation of nanocomposites was reflected through the unexpected improvement of thermal and mechanical properties; for example, the tensile strength of a nanocomposite containing only 4 wt % organophilic clay was doubled in comparison with that of pure EVA‐28, and the thermal stability of the same nanocomposite was higher by about 34 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2065–2072, 2002     

Oxidation behaviour of precipitation hardened steel TG,X-Ray,XRD and SEM study

In the present work the oxidation behavior of ageing treated steel was examined up to 1000°C in different environments (O₂ and CO₂) and with different heating rates. The examination was conducted by means of thermogravimetric analysis, scanning electron microscopy and X-ray diffraction. In this study it was deduced that in the case of O₂ an oxide scale is formed on top of the steel. The oxidation is uniform and the growth of the scale is more intent at low heating rate. It consist of different Fe, Mn, Mo and Cr oxides which are adjusted in the form of layers. This phenomenon was explained by the different diffusion coefficients of each metal in the already formed scale. Regarding the oxidation in CO₂, the scale formation takes place at a lower temperature than in the case of O₂. Hence the examined substrate is more vulnerable in CO₂.     

Sensitive Electrochemical Determination of Hydrogen Peroxide Using Copper Nanoparticles in a Polyaniline Film on a Glassy Carbon Electrode

Rapid and accurate determination of hydrogen peroxide is necessary in biochemistry and environmental science. In this paper, a sensitive hydrogen peroxide electrochemical sensor was developed by cyclic voltammetry deposition of polyaniline–copper nanocomposite film on a glassy carbon electrode. The synthesized polyaniline/Cu composites were characterized by scanning electron microscopy and X-ray diffraction. With a typical working potential of 0.4?V (versus Ag/AgCl) and a pH value of 6.0, the prepared electrochemical sensor achieved linear range of 1.0–500?µM for hydrogen peroxide detection. A relative standard deviation of 4.9% for n?=?7 and 10.0?µM of H₂O₂ and a limit of detection of 0.33?µM at a signal-to-noise ratio?=?3 were observed. The sensor was successfully used for the analysis of tap water, and a spiked recovery of 93.0?±?2.1% was obtained, further confirming the sensor’s accuracy and feasibility.     

Synthesis and characterization of interpenetrating polymer networks with nonlinear optical properties

We report the synthesis and characterization of interpenetrating polymer networks (IPNs) exhibiting nonlinear optical (NLO) properties. The network consists of aliphatic polycarbonate urethane (PCU) and poly(methyl methacrylate-co-N,N-disubstituted urea), with a nonlinear optical (NLO) chromophore incorporated into N,N-disubstituted urea. The full IPNs have only one T_g, as determined by differential scanning calorimetry (DSC), together with scanning electron microscopy (SEM) observations, suggest a single phase morphology. The thin films of IPNs are transparent and the unpoled samples produced second harmonic generation (SHG) signals at room temperature. This result indicates that the NLO chromophore is oriented noncentrosymmetrically during the IPN formation process and is tightly held between the permanent entanglements of the two component networks of the IPN. © 1996 John Wiley & Sons, Inc.     

Multi-instrument characterization of HiPIMS and DC magnetron sputtered tungsten and copper films

In this work, copper and tungsten were sputtered onto silicon wafers by direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS). The resulting films were characterized by energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and X-ray diffraction (XRD). By EDX and XPS, all the sputtered films showed only the expected metal peaks. By XPS, the surfaces sputtered by DCMS were richer in oxygen than those produced by HiPIMS. By AFM, the surfaces were quite smooth. The root mean square (RMS) roughness values are as follows: 0.83 nm (W, HiPIMS), 1.10 nm (W, DCMS), 0.85 nm (Cu, HiPIMS), and 1.78 nm (Cu, DCMS). By SEM, the HiPIMS films exhibited smaller grain sizes, which was confirmed by XRD. The crystallite sizes estimated by XRD are as follows: 4 nm (W, body-centered cubic, HiPIMS), 13 nm (W, body-centered cubic, DCMS), 7 nm (W, cubic, HiPIMS), 14 nm (W, cubic, DCMS), 25 nm (Cu, HiPIMS), and 35 nm (Cu, DCMS). By SE, the HiPIMS surfaces showed higher refractive indices, which suggested that they were denser and less oxidized than the DCMS surfaces.     

渣油加氢处理前后沥青质的微观结构研究

采用元素分析、扫描电镜和透射电镜等分析方法对渣油原料中的沥青质、加氢处理后的沥青质及添加高芳香性轻循环油(LCO)反应后的沥青质进行对比研究。结果发现,渣油加氢处理前后沥青质的表面呈现出光滑表面和多孔的球形颗粒表面两种完全不同的形貌。渣油加氢前后沥青质的芳核堆砌表现出明显的长程无序局部有序的特征;加氢处理后的沥青质芳核片层易于堆砌,出现了多层堆砌、长程有序的类石墨结构。渣油中高芳香性LCO的添加有利于促进沥青质的加氢反应、改善沥青质芳核系统在渣油加氢处理过程中的聚集行为。     

Determination of Sulfite in Botanical Medicine Using Headspace Thin-Film Microextraction and Surface Enhanced Raman Spectrometry

A facile method using headspace thin-film microextraction (HS-TFME) coupled with surface enhanced Raman spectrometry (SERS) has been developed for the determination of sulfite in traditional Chinese herbal medicine. The extraction substrate was synthesized by depositing urchin-like ZnO micron particles on glass sheets using chemical liquid phase deposition. Under the optimal conditions, the intensity of the SERS signal at 630–640?cm^?1 provided a good linear relationship with the concentration of sulfite from 25 to 400?mg/kg, and the linear correlation coefficient (R) was 0.996 with a detection limit of 6?mg/kg. The method was employed for the determination of sulfite in herbal medicines, and the results were confirmed by a traditional distillation-titration method. Therefore, this developed HS-TFME-SERS method may play an important role in the rapid, simple, and selective determination of sulfite residues in Chinese herbal medicine and become a potentially universal method for this analyte in various solid samples.     

Synthesis and Electronic Properties of Novel 5,7-Diazapentacene Derivatives

A route to the synthesis of novel 5,7-diazapentacenes and some preliminary studies on their properties is reported. A single crystal X-ray diffraction study of the dihexyl derivative showed it had formed a dimer during the analysis. The materials possess lower lying frontier orbitals than pentacene and may have potential applications in organic electronic devices. This synthetic method may be applicable to the synthesis of other azaacenes.     

Synthesis and characterisation of hexagonal molybdenum nitrides

Four hexagonal molybdenum nitrides—three modifications of δ-MoN and Mo₅N₆—were prepared by the plasma-enhanced chemical vapour deposition (PECVD) method and ammonolysis of MoCl₅ and MoS₂. The nitrides were structurally characterised by X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction. δ₁-MoN is best described by the WC-type structure with stacking faults due to nitrogen atom disorder. Ordering of nitrogen atoms results in δ₂-MoN with the NiAs-type structure. Formation of trigonal molybdenum clusters in δ₃-MoN is responsible for the doubling of the unit cell in a and b directions compared to δ₂-MoN. Mo₅N₆ can be viewed as an intergrowth structure of the WC- and NiAs-type building blocks, accompanied by vacancies on Mo sites. Influence of reaction conditions on the formation of the four nitrides is discussed; their magnetic properties are presented.     

To Study the Effect of Nanoparticle TiO2 on Sodium (Na+) – Ion Conducting Solid Polymer Electrolyte System: [80PEO:20NaPF6]

To study the effect of nanofiller particle TiO₂ on sodium (Na⁺) – ion conducting solid polymer electrolyte (SPE) film: [80PEO:20NaPF₆] and nanocomposite polymer electrolyte (NCPE): [80PEO:20NaPF₆] + xTiO₂, where x = 1–9 wt. (%) have been prepared. SPE film composition: [80PEO:20NaPF₆] selects as Ist-phase host and nano-sized (<100 nm) filler materials TiO₂ as IInd-phase dispersoid. Both SPE and NCPE films have been prepared by the hot-press technique. Filler particle-dependent conductivity study reveals the NCPE system: [80PEO:20NaPF₆] + 8TiO₂ as the highest conducting composition with σ_rt − 3.53 × 10⁻⁶ S cm⁻¹, which is approximately one order of magnitude higher than the SPE optimum conducting composition (OCC) (σ_rt) ≈ 7.78 × 10⁻⁷ S cm⁻¹. Ion transport properties for both SPE and NCPE system have been evaluated in terms of ionic conductivity (σ) and total ionic (t_ion)/cationic (t₊) transference numbers using combined AC/DC techniques in order to evaluate its usefulness in all-solid-state battery applications. Structural/thermal properties have been characterized using X-ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques. A cyclic voltammetry (CV) study has been performed in SPE and NCPE OCC film to evaluate the electrochemical performance for battery application.     

Hydrothermal synthesis and characterization of nanocrystalline ZrO2 and surface modification with 2-acetoacetoxyethyl methacrylate

For the utilization as inorganic/organic hybrid nanomaterials for optical purposes, nanocrytalline tetragonal ZrO₂ was synthesized by hydrothermal method using zirconium(IV)-n-propoxide as precursor material. Surface of the ZrO₂ particles was then modified with 2-acetoacetoxyethyl methacrylate used as a copolymer for coatings. X-ray diffraction analysis revealed that both ZrO₂ and modified ZrO₂ are in tetragonal crystalline phase. As proved by transmission electron microscope and particle size analysis, average particle sizes of ZrO₂ and modified ZrO₂ were found as 6.22 and 14.7 nm, respectively. ZrO₂ powder was easily dispersed either in water or n-hexane. Ultraviolet diffuse reflectance spectrophotometer analysis for ZrO₂ and surface modified ZrO₂ showed that maximum absorption peaks are at 215 and 225 nm, respectively.     

Morphological characterization of poly(phenylacetylene) nanospheres prepared by homogeneous and heterogeneous catalysis

Scanning electron microscopy characterization of the materials obtained by homogeneous and heterogeneous catalytic polymerization of phenylacetylene is described. The catalysts used are β‐dioxygenato rhodium(I) complexes. The effects of the reaction medium, presence of a cocatalyst and the type of catalysis (homogeneous or heterogeneous) on the morphology of the polymers obtained have been studied and discussed. Using a supported complex at 0 °C, nanoparticles with a diameter distribution as narrow as 30 to 70 nm were obtained. Polymer nanopowders were found to be unaffected by ageing. Copyright © 2003 John Wiley & Sons, Ltd.     

Structural characteristics of soluble fullerene films

Films of two fullerenes, functionalized with different solubilizing moieties, in the pure form and blended with poly(3-hexylthiophene), have been investigated by cyclic voltammetry, X-ray diffraction and UV-Vis spectroscopy techniques. The conclusion drawn from this characterization is that the supramolecular order of the films affects the physicochemical characteristics of these materials, and depends on the nature of the solubilizing substituents linked to the fullerene moiety. Implications for the use of such films in fullerene-based solar cells are also presented and discussed.     

硅化钴的简单固相合成与磁学性能

使用Co_3O_4、金属镁和硅为原料在不锈钢高压釜750℃反应得到立方相的硅化钴(CoSi)。所得样品的结构和形貌利用X射线粉末衍射(XRD)、透射电子显微镜(TEM)和场发射扫描电子显微镜(FESEM)等手段表征。XRD结果表明,所得样品为立方相CoSi,晶格常数为a=0.445 5 nm。此外,研究了CoSi样品的磁性和抗氧化性能,结果表明通过上述方法制备得到的硅化钴材料具有铁磁性,在600℃以下具有较好的稳定性和抗氧化性能。     

Synthesis,characterization, and electrochemical studies of Co(II,III) dithiocarbamate complexes

Cobalt(II) complexes of N-methyl phenyl, 1-phenylpiperazyl, and morpholinyl dithiocarbamates have been synthesized and characterized by UV–Visible, FTIR, ¹H-, ¹³C-NMR, and mass spectrometry. The spectroscopic data indicated that two ligands coordinated in bidentate chelating to the metal ion to form four-coordinate cobalt(II) complexes (1–3), which was confirmed by mass analysis (TOF MS ES⁺) of the complexes with m/z [M]⁺ = 450.98, 382.94, and 382.94 for 1, 2, and 3, respectively. Single crystal analysis of 2A and 3A show centrosymmetric mononuclear cobalt(III) bonded to three dithiocarbamate ligands forming a distorted octahedral geometry, indicating the cobalt(II) undergoes aerial oxidation to cobalt(III) during recrystallization. In addition, 2A crystallized with one solvated molecule of toluene. The redox behaviors of the complexes were studied by cyclic and square wave voltammetry in dichloromethane; the result revealed a metal centered redox process consisting of a one-electron quasi-reversible process assigned to Co(III)/Co(IV) oxidation and a corresponding Co(IV)/Co(III) reduction. Randles–Sevcik plots (anodic peak current versus the square root of the scan rate (I_p,a versus ν^1/2)) for the redox couples revealed diffusion-controlled behavior.