A plasmonic mercury sensor based on silver–gold alloy nanoparticles electrodeposited on indium tin oxide glass

We construct silver–gold alloy nanoparticles (Ag–AuNPs) as the basis of a reagentless, sensitive and simple mercury sensor. Ag–AuNPs were electrodeposited directly on transparent indium tin oxide film coated glass. Hg(II) ions in aqueous solution could be reduced by Ag atoms existing in Ag–AuNPs; the deposition/amalgamation of Hg on the nanoparticles resulted in a blue shift of the localized surface plasmon resonance peak. Therefore, Hg^2 + can be detected quantitatively by using a spectrophotometer. The sensor response is linear in the range from 0.05 to 500 ppb of Hg(II) concentration. No sample separation or preconcentration is required for detection of ultralow levels of mercury in water samples. The results shown herein have potential applications in the development of a new optical sensor for the detection of low concentrations of mercury.     

Oxidation for unsymmetrical bromo-1,10-phenanthrolines and subsequent hydroxylation,decarbonylation and chlorination reactions

A systematic investigation on the oxidation of unsymmetric bromo-phens is presented herein, where the reaction temperature is found to be the key parameter to generate oxidation or oxidation-bromination products. The regioselective C3-brominated compounds are produced in moderate yields in the cases of 2-bromo-phen and 4-bromo-phen. Subsequent hydroxylation and decarbonylation for bromo-phds are also studied, where a series of bromo-diazafluorenones and phen-triones have been isolated. Furthermore, various chlorination products have been obtained by treating bromo-phds or bromo-phts with excess POCl₃.     

Transient and Recyclable Halogenation Coupling (TRHC) for Isoflavonoid Synthesis with Site-Selective Arylation

A transient and recyclable C−H iodination has been designed for the synthesis of isoflavonoids through the domino reactions of o-hydroxyphenyl enaminones and aryl boronic acids in the presence of catalytic KI and Pd catalyst. Instead of the conventional cross-coupling strategy employing pre-halogenated substrates, this method transforms raw C−H bond by means of a transient C−H halogenation to smoothly relay the subsequent C-arylation. Consequently, such a method avoids the pre-functionalization for C−halogen bond installation as well as the generation of stoichiometric halogen-containing waste following the cross-coupled product, disclosing an intriguing new coupling protocol to forge the C−C bond in the virgin area between classical C−X (X=halogen) bond cross coupling and the C−H activation.     

Effects of additives and post‐treatment on the thermoelectric performance of vapor‐phase polymerized PEDOT films

Vapor‐phase polymerization (VPP) is an important method for the fabrication of high‐quality conducting polymers, especially poly(3,4‐ethylenedioxythiophene) (PEDOT). In this work, the effects of additives and post‐treatment solvents on the thermoelectric (TE) performance of VPP‐PEDOT films were systematically investigated. The use of 1‐butyl‐3‐menthylinidazolium tetrafluoroborate ([BMIm][BF₄], an ionic liquid) was shown to significantly enhance the electrical conductivity of VPP‐PEDOT films compared with other additives. The VPP‐PEDOT film post‐treated with mixed ethylene glycol (EG)/[BMIm][BF₄] solvent displayed the high power factor of 45.3 μW m^?1 K^?2 which is 122% higher than that prepared without any additive or post‐treatment solvent, along with enhanced electrical conductivity and Seebeck coefficient. This work highlighted the superior effect of the [BMIm][BF₄] additive and the EG/[BMIm][BF₄] solvent post‐treatment on the TE performance of the VPP‐PEDOT film. These results should help with developing the VPP method to fabricate high‐performance PEDOT films. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 1738–1744     

Two 2D uranyl coordination complexes showing effective photocatalytic degradation of Rhodamine B and mechanism study

Two new hydrostable two-dimensional(2 D) uranyl coordination complexes [(UO_2)_5(μ_3-O)_2(nbca)_2].7 H_2O(1) and [(UO_2)_3(nbca)_2(H_2O)_3]·2 H_2O(2)(H_3 nbca=5-nitro-1,2,3-benzenetricarboxylic acid) were hydrothermal synthesized.Single-crystal structural refinements reveal that both of the two complexes were formed by the packing of 2D uranyl coordination sheets via the hydrogen bonds.The nbca ligand coordinating to the uranyl polyhedron centers constructed the 2D sheets.There are UO_8 hexagonal bipyramids and UO_7 pentagonal bipyramids in 1 while only U07 pentagonal bipyramids in 2.Photocatalytic degradation of rhodamine B(RhB) in aqueous solution was studied.Complex 2 possesses better performance than 1 with 96.2 % of the RhB was degraded in only 60 min.Mechanism studies reveal that the dissolved oxygens are essential to the RhB degradation.The photocurrent density of 2 is more stable than that of 1,which indicating the stronger ability to separate photoexcited electrons and hole pairs of 2.     

Thermally driven self-healing PEDOT conductive films relying on reversible and multiple Diels–Alder interaction

Thermally healing capability of cracks and defects is important and urgent for the safe operation and life extending of electric materials and devices. Here, by the combination of thermally driven reversible Diels–Alder (DA) interaction and in-situ chemical oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT), a series of intrinsically conductive poly(3,4-ethylenedioxythiophene) (PEDOT)/DA composites possess intrinsically self-healing property under low-temperature (reverse DA reaction at 100°C; DA crosslinking at 60°C) stimulus were achieved. The crosslinking DA bonding reactions are multiple from the co-existence of pre-synthesized macromolecular polyurethane attached DA units (PU-DA) and 2,4-hexadiyne-1,6-diol (DADOL) in the films. PU-DA involved in the polymerization process of EDOT to endow PEDOT with outstanding solution-processability, uniform film making, and structural self-healing capability, while DADOL was added to enhance the cross bonding between polymer chains. This work will accelerate the research and application development of intrinsically self-healing conducting polymers for commercial capacitors, antistatic coatings, implantable, printable electronics, and so on.     

Cobalt(II)-Catalyzed [4+2] Annulation of Picolinamides with Alkynes via C−H Bond Activation

A cobalt(II)-catalyzed [4+2] annulation of picolinamides with alkynes via C−H bond activation has been developed. The operationally simple annulation reaction allows for the synthesis of acyl-substituted 1H-benzoquinoline bearing multiple aromatic rings (up to 96 % yield) without co-oxidant or other oxidation factors under mild conditions. Several control experiments were carried out. This practical [4+2] annulation provides an efficient route to access highly functionalized compounds.     

Kinetics and isothermal adsorption of U(VI) in aqueous solution by nano-Ni0

Journal of Radioanalytical and Nuclear Chemistry - The nanoscale zero-valent nickel (nano-Ni0) was prepared by liquid-phase reduction method and characterized by BET, XPS, FT-IR and XRD and be used...     

Euler-Bernoulli梁的高阶二次摄动解及收敛性讨论

首次用解析的方式给出了Euler-Bernoulli梁后屈曲与非线性弯曲问题的高阶二次摄动解答.假定梁的中线不可伸长，用精确曲率公式与能量变分原理导出了非线性Euler-Bernoulli梁的模型.通过与精确解或高阶摄动解的比较，讨论了二次摄动解答的收敛性及适用域.得到主要结论如下:低阶摄动解适用于描述梁的初始后屈曲阶段及初始非线性弯曲阶段；更高阶次的摄动解适用于描述梁的深度后屈曲以及深度非线性弯曲.从这个意义上去说，该文不仅仅指出某些文献上的部分结果不精确是由于摄动解答超出了其特定的适用域，并且还进一步发展与完善了二次摄动法.     

Bayesian Estimation and Statistical Analysis of Risk Measurements

The Bayesian model are established for the VaR and related risk measurements. The relationship between VaR and other risk measurements including expect shortfall, tail condition expectation and conditional value at risk are discussed. Furthermore, the Bayesian estimates and Bayesian predictors of these risk measurement are derived. Thirdly, the consistency and asymptotic normality in the exponential risk model are proved. Finally, the numerical simulation method is used to verify the convergence rate under different sample sizes.